EPA-450/3-73-003a
EMISSIONS CONTROL
IN THE GRAIN
AND FEED INDUSTRY
VOLUME I - ENGINEERING
AND COST STUDY
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
-------
EPA-450/3-73-003a
EMISSIONS CONTROL
IN THE GRAIN
AND FEED INDUSTRY
VOLUME I - ENGINEERING
AND COST STUDY
by
Dr. Larry J. Shannon, Richard W. Gerstle, P. G. Gorman,
D. M. Epp, T. W. Devitt, and R. Amick
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri
Contract No. 68-02-0213
EPA Project Officer: Kenneth R. Woodard
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, N. C. 27711
December
»„');-<• ... , - <~~>i
-------
This report is issued by the Environmental Protection Agency to
report technical data of interest to a limited number of readers.
Copies are available free of charge to Federal employees, current
contractors and grantees, and nonprofit organizations - as supplies
permit - from the Air Pollution Technical Information Center,
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, or from the National Technical Information Service, 5285
Port Royal Road, Springfield, Virginia 22151.
This report was furnished to the Environmental Protection Agency by
Midwest Research Institute, Kansas City, Missouri, in fulfillment of
Contract No. 68-02-0213. The contents of this report are reproduced
herein as received from the Midwest Research Institute. The opinions,
findings, and conclusions expressed are those of the author and not
necessarily those of the Environmental Protection Agency. Mention of
company or product names is not to be considered as an endorsement
by the Environmental Protection Agency.
Publication No. EPA-450/3-73-003a
ii
-------
PREFACE
This report was prepared for EPA/OAQPS under Contract No. 68-02-0213,
which was monitored by Mr. Kenneth R. Woodard.
The program was performed with MRI as prime contractor and PEDCo-
Environmental, Cincinnati, Ohio, as subcontractor. The program was centered
in MRI's Physical Sciences Division, Dr. H. M. Hubbard, Director. Dr. A. E.
Vandegrift, Assistant Director, Environmental Programs, served as Program
Manager and coordinated activities between PEDCo and MRI and between MRI's
Physical Sciences Division and Economics and Management Science Division.
Dr. Larry J. Shannon, Head, Environmental Systems Section, was Principal
Investigator for MRI and Mr. Richard Gerstle was Principal Investigator for
PEDCo.
Other MRI staff members who contributed significantly to the program
were Mr. Paul Gorman, Mr. Dan Epp, and Miss Christine Guenther. Other PEDCo
staff members who contributed were Mr. Timothy Devitt, and Mr. Robert Amick.
Approved for:
MIDWEST RESEARCH INSTITUTE
H. M. Hubbard, Director
Physical Sciences Division
iii
-------
ACKNOWLEDGMENTS
Numerous people outside Midwest Research Institute and PEDCo-Environmental
made significant contributions to the success of this program.
Industry trade associations such as the National Grain and Feed Associa-
tion, American Feed Manufacturers Association, Corn Refiners Association,
Millers National Federation, and American Dehydrators Association provided
valuable assistance during various stages of the program.
Several individuals associated with dust control equipment manufacturing
companies provided information on control equipment performance, equipment
costs, and related information. Foremost in this regard were Mr. Maurice P.
Schrag, Hart-Carter Company; Mr. Jack Kice, Kice Metals Company; Mr. Hans
Wanzenried, Buhler Corporation; Mr. John R. Danciak, Airotech Sales Company
(representative for MikroPul); and Mr. Kenneth Cox, Natkin and Company.
The program could not have been completed without the assistance of many
individual companies who graciously permitted MRI, PEDCo-Environmental, and
EPA personnel to visit their engineering offices and individual plants and
mills. Cargill, Inc., was especially helpful in this regard. Mr. Don S.
Macgregor, Assistant Vice President, coordinated Cargill efforts. Other
Cargill personnel who generously gave their time and knowledge were Mr. Robert
F. Hubbard, Mr. Charles L. Anderson, Mr. E. H. Gustafson, Mr. Dan Inge, and
Mr. Robert F. Ambler. Other firms and individuals who made significant con-
tributions were: Simonds-Shields-Theis Grain Company (Mr. W. C. Theis),
St. Louis Grain Corporation (Mr. James A. Layton), The Pillsbury Company
(Mr. Richard A. Coonrod, Mr. James C. McNeil, and Mr. Doug Fiscus), General
Mills (Mr. W. J. Mahoney), Seaboard Allied Milling Corporation (Mr. Harry
Stapleton), Farmland Industries, Inc. (Mr. C. H. Chandler), and Hubbard Mill-
ing Company (Mr. Nick Scheuer).
Members of the industry liaison committee who reviewed the draft of this
report are also thanked for their efforts.
The guidance and assistance provided by the project officer, Mr. Kenneth R.
Woodard of the Office of Air Quality Planning and Standards, Emission Standards
and Engineering Division is gratefully acknowledged.
iv
-------
TABLE OF CONTENTS
Acknowledgements „ iv
List of Tables xiii
List of Figures xxiii
Summary „ xxvi
Chapter 1 - Introduction 1
Purpose of the Study 1
Scope of Study 1
Organization of the Study 2
Chapter 2 - Industry Statistics 4
Introduction 4
Grain Production. 4
Grain Production and Utilization 4
Grain Movement 7
Terminal Markets 12
Grain Elevators 15
Number and Capacity of Elevators 16
Transportation Mode 18
Volume of Grain Handled 20
Grain Storage 22
Grain Drying and Cleaning 23
Location 23
Industry Structure 25
Formula Feed Industry 28
Introduction 28
Materials Used 30
Industry Structure. ..... 34
Size of Mills 35
Plant Location 37
Characteristics of Feed Manufacturing Firms 37
-------
TABLE OF CONTENTS (Continued)
Page
Chapter 2 - (Concluded)
Alfalfa Dehydrating Industry 40
Introduction 40
Raw Materials and Products 40
Industry Structure 44
Characteristics of Plants 48
Grain Milling 49
Introduction 49
Raw Materials and Products 49
Industry Structure 55
Characteristics and Trends in Grain Milling 72
Commercial Rice Drying 75
Introduction 75
Industry Structure 75
Characteristics of Plants 77
Rice Milling 81
Introduction 81
Raw Materials and Products 81
Industry Structure « 81
Characteristics of Mills 87
Soybean Oil Processing 88
Introduction 88
Soybean Production 88
Characteristics of the Soybean Milling Industry 91
Corn Wet Milling 99
Introduction 99
Raw Materials and Products 100
Industry Structure 101
Characteristics of Plants 101
References. 107
vi
-------
TABLE OF CONTENTS (Continued)
Chapter 3 - Processes and Emissions 109
Introduction ........ . 109
Grain Elevators (Grain Marketing Operations) 109
Grain Elevator Operations. 110
Air Pollution Sources, Emission Rates, and Effluent Properties . 117
Feed Mills „ 155
Feed Manufacturing Process ...... 155
Air Pollution Sources, Emission Rates, and Effluent Properties . 159
Alfalfa Dehydrating Plants 169
Alfalfa Dehydrating Process 169
Air Pollution Sources, Emission Rates, and Effluent Properties . 171
Wheat Milling „ 203
The Milling of Wheat 203
Air Pollution Sources, Emission Rates, and Effluent Properties . 207
Durum Wheat Milling 214
Durum Milling Process 214
Air Pollution Sources, Emission Rates, and Effluent Properties . 215
Corn Dry Milling 216
The Dry Milling of Corn 216
Air Pollution Sources, Emission Rates and Effluent Properties. . 219
Rye Milling 221
Rye Milling Process 221
Air Pollution Sources, Emission Rates and Effluent Properties. . 225
vii
-------
TABLE OF CONTENTS (Continued)
Chapter 3 - (Concluded)
Oat Milling 227
The Milling of Oats 227
Air Pollution Sources Emission Rates, and Effluent Properties. 233
Rice Milling 235
Rice Milling Process 235
Milling Section 239
Air Pollution Sources, Emission Rates, and Effluent
Properties 240
Commercial Rice Drying 242
Commercial Rice Drying Facilities 242
Air Pollution Sources, Emission Rates, and Effluent
Properties 243
Soybean Processing 245
Soybean Plant Operations 245
Air Pollution Sources, Emission Rates, and Effluent
Properties 248
Corn Wet Milling 253
Corn Wet-Milling Process 253
Air Pollution Sources, Emission Rates and Effluent
Properties 260
References 269
Chapter 4 - Technical and Economic Aspects of Dust Control
Systems 273
Introduction 273
Dust Control Systems 275
Dust Capture Systems 275
Types of Air Pollution Control Devices 275
viii
-------
TABLE OF CONTENTS (Continued)
Chapter 4 - (Concluded)
Currently Used Control Systems 292
Grain Handling Operations 292
Grain Dryers 314
Feed Mills 314
Wet Corn Milling 315
Soybean Processing 316
Grain Milling 316
Control System Costs 317
Control Device Costs 317
Recovered Dust Value 329
Insurance Credits for Installation of Control Devices 329
References. 330
Chapter 5 - Economic Impact of Dust Control 332
Introduction 332
Grain Elevators 336
Description of Model Plants 336
Control Equipment Costs 336
Credits for Dust Control. 347
Financial Statements 350
Application of Controls to Existing Elevators 361
Economic Impact on New Plants 369
Impact on Existing Facilities 371
Feed Mill 374
Description of Model Plant 374
Control Equipment Costs 376
Credits for Dust Control 379
Financial Statements 379
Economic Impact of Control Systems on Industry. . . 382
Alfalfa Dehydrating Plant 390
ix
-------
TABLE OF CONTENTS (Continued)
Page
Chapter 5 - (Continued)
Description of Model Plant 390
Control Equipment Costs 390
Financial Statement 393
Economic Impact of Control Systems on Industry 396
Wheat, Rye, and Durum Milling 399
Description of Model Plant < 399
Control Equipment Costs 399
Credits for Dust Control 403
Financial Statements 404
Economic Impact of Control Systems on Industry 409
Durum Flour Milling. 414
Dry Corn Milling 421
Description of Model Plants 421
Control Equipment Costs 421
Credits for Dust Control 425
Economic Impact of Control Systems on Industry 425
Rice Milling 431
Description of Model Plant 431
Control Equipment Costs 431
Credits for Dust Control 435
Financial Statements 435
Economic Impact of Control Systems on Industry ........ 439
Commercial Rice Drying 442
Description of Model Plants 442
Control Equipment Costs 445
Credits for Dust Control 445
Financial Statements 448
Economic Impact of Control Systems on Industry 450
x
-------
TABLE OF CONTENTS (Continued)
Page
Chapter 5 - (Concluded)
Soybean Processing Plant 454
Description of Model Plant 454
Control Equipment Costs ..... 454
Credits for Dust Control 458
Financial Statements 458
Economic Impact of Control Systems on Industry 462
Corn Wet Milling 467
Description of Model Plant 467
Control Equipment Costs 467
Credits for Dust Control 473
Financial Statements 473
Economic Impact of Control Systems on Industry 480
References 482
Chapter 6 - Air Pollution'Episode Procedures 484
Introduction 484
Episode Criteria 484
Specific Episode Plan Responsibilities 486
Emission Control Strategies 488
Grain Elevator Operations 489
Feed Manufacturing 489
Soybean Processing 489
Wet Corn Milling 490
Dry Milling of Wheat, Rice and Corn 490
Alfalfa Dehydrating 490
Unique Problems Encountered in Episode Control Plans . 491
Episode Control Costs 491
References 492
Chapter 7 - Source Surveillance and Monitoring 493
Introduction 493
Emission Measurements 493
xi
-------
TABLE OF CONTENTS (Continued)
Chapter 7 - (Concluded)
Source Testing Procedures 493
Recommended Particulate Sampling Procedure 499
Ambient Air Monitoring 501
References .„ 502
Chapter 8 - Field Surveillance and Enforcement 503
Introduction 503
Introduction to Inspection Practices ... 503
Observing the Plant Environment 504
Interviewing Plant Personnel 504
Inspecting Inside the Plant 504
Field Inspection Equipment 505
Basic Equipment Needs 505
Field File 506
Inspection Procedures 506
Inspection of Air Pollution Control Systems 511
Chapter 9 - Recommendations for Future Programs 514
Areas of Needed Research 514
Specific Research Programs . 514
Dust Control Systems 514
Source Testing Methods 515
Emission Factors 515
Financial Data 515
Health and Welfare Effects of Emissions 516
Appendix A - Harvesting Techniques and Their Influence on Dust
Emissions at Grain Elevators 517
Appendix B - Health Effects of Effluents from the Grain and Feed
Industry 522
Appendix C - Example of Emissions Inventory Questionnaire. .... 531
xii
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title Page
1 Response to Emissions Inventory Questionnaire by Grain
and Feed Industry Firms 2
2 Quantity and Value of Production of Major Grains 5
3 Production and Farm Disposition* of Grain 6
4 Supply and Distribution of Grains, U.S. Year Beginning
1971 8
5 Grain Receipts at Terminal Markets, 1970 13
6 Freight Traffic in Port Terminals, Foreign Exports and
Coastwide Shipments 14
7 Number and Capacity of Warehouses Under Uniform Grain
Storage Agreement 17
8 Grain Elevators - Number of Establishments and Value of
Sales 19
9 Receipt and Loadout of Grain by Transportation Mode at
Grain Elevators 20
10 Number and Capacity of Grain Storage Facilities Under
Uniform Grain Storage Agreement by States as of
September 30, 1972 24
11 Country Elevators within Metropolitan Areas - 1967 .... 25
12 Ownership of Country Elevators--1963 26
13 Concentration of Ownership of Country Elevators 26
14 Ownership of Terminal Elevators 27
15 Value of Formula Feed Shipments from Feed Industry .... 29
16 Formula Feed from Primary Manufacturing Establishments
Producing 1,000 Tons or More of Feed 31
17 Feed Concentrate Balance, Number of Animal Units, and
Feed Per Unit, Average 1965-69, Annual 1967-72 32
18 Processed Feeds: Estimated Use for Feed Average 1966-70
Annual 1968-72 33
19 Formula Feed Industry (Census of Manufacturers) 35
20 Production of Feed Manufacturing Establishments by Size, 1969. 36
21 Capacity of Feed Manufacturing Establishments Producing
1,000 Tons or More of Feed 36
22 Location of Formula Feed Plants 38
23 Percent of Shipments Accounted for by Largest Companies
in the Feed Industry 41
24 Type of Operation in Feed Industry 42
25 Ownership of Feed Establishments with Production of Over
1,000 Tons 42
26 Dehydrated Alfalfa Production and Utilization 1948-49
to 1971-72 Seasons 45
xiii
-------
TABLE OF CONTENTS (Continued)
List of Tables
Title Page
Dehydrated Alfalfa Meal: Production, Stocks, Exports
and Domestic Utilization U.S., by Months 1967-71 ... 46
28 Northern Plains Alfalfa Meal Production 47
29 Quantity and Value of Products From Alfalfa Dehydrating
Plants 48
30 Products of Grain Milling Plants 50
31 Quantity and Value of Shipments from Grain Mills in 1963
and 1967 51
32 Summary: Commercial Wheat Milling Production: 1965 to
1971 53
33 Commercial Wheat Milling Production, by Geographic Areas:
1971 and 1970 54
34 United States Durum Production by States, 1961-69. ... 56
35 Durum Wheat Products: 1971 and 1970 57
36 Yearly Average Bushel Production of Rye by States. ... 57
37 Commercial Rye Milling Production, By Months: 1971 and
1970 58
38 Corn: Supply and Distribution, United States, 1964-71 . 59
39 Oats: Supply and Distribution, United States, 1964-71 . 60
40 General Statistics for Grain Milling Plants 62
41 Percent of Value of Shipments Accounted for by the
Largest Companies in Grain Milling 63
42 Wheat Flour Milling by States 64
43 Largest Wheat Flour Milling Companies 65
44 Largest Wheat, Rye and Durum Milling Companies 66
45 Relative Size of Active and Inactive Wheat Flour Mills . 67
46 Changes in Wheat Flour Mills and Milling Capacity. ... 67
47 The Percentage Distribution of Durum Mills by Capacity
of Plants, United States, 1945, 1951, 1961, 1965, 1969,
and 1971 68
48 Durum Milling by States 69
49 Number, Capacity, and Concentration Ratios of the Durum
Milling Industry in the United States, 1945, 1951,
1961, 1965, 1969 70
50 Geographical Distribution of Dry Corn Mills in Continen-
tal United States (1971) 71
51 Corn Usage Pattern in Dry Corn Mills 72
52, Rye Flour Milling by States 73
53 Types of Milling Unit s in Operation, by Tiee of Installa-
tion, by Region 74
xiv
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title Pag€
54 Functions Other Than Milling Wheat Flour Performed at Plant
1964-65 Marketing Year 76
55 Number and Total Plant Capacity of Rice Dryers in Universe
and Sample, by Region and Quartile Groupings, 1965-66 ... 78
56 Estimated Total Plant Capacity and Utilization for Rice
Handling and Storing by Regions, 1965-66 . 79
57 Estimated Volumes of Rough Rice Handled, at Commercial Rice
Dryers, by Regions, 1965-66 79
58 Receipts of Rough Rice by Mode of Transportation and Compared
With Total Capacities, by Regions, 1965-66 80
59 Comparison of Volumes of Rough Rice Dried to Volumes
Received and to Total Capacities, by Regions, 1965-66 ... 80
60 Rice, Rough: Supply and Distribution, United States,
1949-71 . 82
61 Rice, Milled: Supply and Distribution, United States,
1949-70 ..... 83
62 Quantity and Value of Shipments of Products from Rice Mills . 84
63 Value of Product Shipments from Rice Mills 85
64 Distribution of Rice Mills in 1971 85
65 General Structure of Rice Milling Industry 86
66 Percent of Value of Shipments Accounted for by the Largest
Companies in Rice Milling Industry 86
67 Comparison of Major Crops: Acreage and Dollar Value. .... 89
68 Acreage Harvested and Total Production of Soybeans for
Beans, 1950-71 90
69 Number of Soybean Oil Mills and Processing Capacity in the
United States, 1960-71 92
70 Estimated Number of Soybean Oil Mills in the United States
by Regions and States, 1951-1970 93
71 Value of Shipments Soybean Oil Mill Products, 1958-70 .... 94
72 Production of Soybean Oil Mill Products, 1958-67 95
73 Soybean Oil Utilization by Classes of Products United States,
1958-70 97
74 Percent of Value Shipments Accounted for by the largest Com-
panies in Soybean Oil Milling, 1958-70 98
75 Trends in Corporation Structure in the Soybean Milling In-
dustry, 1958-67 99
76 Corn Purchasing Patterns for Major Firms in Corn Wet Milling
Industry 100
xv
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title Page
77 Shipments by Corn Refining Industry of Products Manu-
factured From Corn Annually, 1957-66 102
78 Quantity and Value of Shipments by All Producers in Corn
Wet Milling Industry, 1967 and 1963 103
79 Value of Shipments by Corn Wet Milling Plants in Last 25
Years . . . . 104
80 General Statistics for Starch Producers: 1958-67 105
81 Particulate Emissions from Grain Handling and Processing. . 118
82 Measured Emission Rates for Grain Receiving and Handling
Operations 122
83 Emissions From Grain Unloading Operations, Elevator C . . . 123
84 Emissions From Truck Unloading Stations 125
85 Emission Data for Cyclone System Serving a Truck Dump ... 127
86 Summary of Emission Measurements on Truck Receiving Pits
at Grain Elevators 128
87 Measured Emission Rates for Barge Unloading Operations. . . 130
88 Emissions From Aeroglide Rack Dryer Controlled by Wiedenmann
Screen Kleen 134
89 Emissions From Hess Rack Dryer Controlled by Day-Vac Dust
Filter 136
90 Summary of Grain Dryer Emission Test Conducted for Illinois
Institute for Environmental Quality . 137
91 Dust Emission Test on 2,000 Bu/Hr Aeroglide Rack Grain
Dryer 139
92 Summary of Results of Emission Tests on Zimmerman Con-
tinuous Flow Grain Dryer 139
93 Summary of Results of Emission Tests on Mathews Company
Model 900 Grain Dryer 140
94 Summary of Results of Emission Tests on Berico Industries
Turn-Flo Dryer 140
95 Summary of Available Emission Tests on Grain Dryers .... 142
96 Emissions From Grain Cleaning 143
97 Emissions From Grain Cleaning Operations 144
98 Measured Emission Rates for Scale System. . 146
99 Emissions From Elevator Leg Controlled by Cyclone
Collector 146
100 Particle Size Distribution for Leg Cyclone Inlet Test . . . 147
101 Emissions From Grain Turning Operations Controlled by
Cyclones 149
xvi
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title Page
102 Emissions From Tunnel Belt Dust Control System in a Terminal
Elevator 150
103 Dust Emissions From Grain Handling Operations 153
104 Dust Emissions From Grain Handling Operations 154
105 Estimated Emission Rates for Ingredient Receiving Operations
in Feed Mills 160
106 Measured Emission Rates From Transfer Systems on Grinding
Equipment in Feed Mills 163
107 Measured Emission Rates From Pellet Coolers at Feed Mills . . 164
108 Measured Emission Rates From Horizontal Pellet Coolers at
Texas Feed Mill 167
109 Estimated Emissions From Pellet Cooler Cyclone Systems. . . . 168
110 Process Parameters for Alfalfa Dehydration Plants 177
111 Alfalfa Dehydration, Plant A Emissions 178
112 Alfalfa Dehydration, Plant B Emissions 179
113 Alfalfa Dehydration, Plant B Recycle Rates 180
114 Alfalfa Dehydration, Plant C Emissions 181
115 Alfalfa Dehydration, Plant D Emissions 182
116 Alfalfa Dehydration, Test Results Control Device/System - A . 187
117 Alfalfa Dehydration, Test Results Control Device/System - B . 188
118 Alfalfa Dehydration, Test Results Control Device/System - C . 189
119 Alfalfa Dehydration, Test Results Control Device/System - D . 192
120 Alfalfa Dehydration, Test Results Control Device/System - E . 194
121 Alfalfa Dehydration, Test Results Control Device/System - F . 196
122 Alfalfa Dehydration, Test Results Control Device/System - G . 197
123 Alfalfa Dehydration Plant Emission Factors 198
124 Alfalfa Dehydration Plant Emission Factors 199
125 Alfalfa Dehydration Plant Emission Factors 200
126 Comparison of Alfalfa Dehydration Plant Emission Factor Data. 202
127 Potential Sources of Air Pollutants in a Flour Mill Complex . 208
128 Dust Emissions From Cleaning House Processes at a Wheat
Flour Mill 210
129 Grain Loadings in Ducts, of Flour Mill Suction Systems .... 211
130 Estimated Emissions From Various Operations in Flour Mills . . 212
131 Estimated Emissions From Cyclone Dust Control Systems at
a Flour Mill 213
132 Potential Sources of Air Pollutants in a Dry Corn Mill. . . . 220
133 Measured Emission Rates From Controlled Sources in a Dry
Corn Mill 222
xvii
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title Page
134 Estimated Emission Rates From Various Sources in a Dry
Corn Mill. „ 223
135 Potential Sources of Air Pollutants in a Rye Mill Complex. . 225
136 Estimated Emission Rates From Various Sources in a Rye
Flour Mill 226
137 Potential Sources of Air Pollutants in an Oat Mill 234
138 Measured Emission Rates From Controlled Sources in an Oat
Mill Complex 236
139 Potential Sources of Air Pollutants in Rice Mills 241
140 Particulate Emissions From Selected Operations in a Rice
Mill c 242
141 Potential Sources of Air Pollutants in Soybean Processing
Plants 250
142 Measured Emission Rates From Truck Dump Pit Aspiration
System at a Soybean Plant 251
143 Measured Emission Rates From Selected Sources at a Soybean
Processing Plant 251
144 Measured Emission Rates From Selected Sources at a Soybean
Processing Plant 252
145 Estimated Dust Emission Rates From Grain Receiving, Handling,
and Cleaning Operations at Various Soybean Processing
Plants 254
146 Estimated Dust Emission Rates From Soybean Grain Dryers at
Various Soybean Processing Plants 255
147 Estimated Dust Emission Rates From Processing Equipment at
Various Soybean Processing Plants 256
148 Potential Sources of Air Pollutants in Corn Wet Milling
Plants 260
149 Measured Emission Rates From Drying Operations at Corn Wet
Milling Plants 262
150 Measured Emission Data for Specific Corn Refining Plants . . 265
151 Chemical and Physical Properties of Effluents From Product
Collection Systems (Cyclones) on Dryer Exhaust 266
152 Volatile Organic Components in Feed Dryer Exhaust Stream . . 268
153 Adequacy of Typical Dust Control Systems - Current
Status, 1972 274
154 Design Parameters for Dust Control Systems in Grain
Elevators, Feed Mills, and Flour Mills 276
xviii
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title Page
155 Cyclone Design Parameter and Its Effect on Efficiency. . . . 279
156 Air Pollution Control Devices Used in the Grain Processing
Industry 293
157 Process Modifications Used to Reduce Dust Emissions From
Grain Handling Operations ....... 296
158 Dust Control Systems for Ship Loading 309
159 Approximate Range of Control Cost 325
160 Summary of Total Annual Operating Costs and Investment Costs
for Control Systems on Grain Elevators 340
161 Model Plant for New Country Elevators (Case 1 - Best
Controls) 341
162 Model Plant for New Country Elevators (Case 2 -
Alternate Controls) 342
163 Model Plant for New Terminal Elevators (Inland)
(Case 1 - Best Controls) 343
164 Model Plant for New Terminal Elevators (Inland)
(Case 2 - Alternate Controls) 344
165 Model Plant for New Terminal Elevators (Port)
(Case 1 - Best Controls) 345
166 Model Plant for New Terminal Elevators (Port)
(Case 2 - Alternate Controls) 346
167 Potential Control Credits for Dust Control to Model
Elevators 351
168 Operation Specifications for Model Plants (Grain
Elevators) 352
169 Yearly Income Statement for New Country Elevator (1972>. . . 354
170 Yearly Income Statement for New Inland Terminal (1972) . . . 355
171 Yearly Income Statement for New Port Terminal (1972) .... 356
172 Balance Sheet for New Country Elevator (1972) 358
173 Balance Sheet for New Inland Terminal (1972) 359
174 Balance Sheet for New Port Terminal (1972) . 360
175 Economic Impact of Controls Applied to New Model Elevators . 362
176 Comparison Between Model Plants and ERS Survey on Impact
of Control Costs (Grain Elevators) 363
177 Country Elevator, Pollution Control of Existing Plants,
Survey of 324 Plants, 1972-73 365
178 Terminal Inland Elevators, Pollution Controls of Existing
Plants, Survey of 196 Plants, 1972-73 366
179 Terminal Port Elevators, Pollution Controls of Existing
Plants, Survey of 12 Plants, 1972-73 367
xix
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title Page
180 Costs and Control. Credits for Controls Applied to Average
Existing Elevator , 368
181 Total Economic Impact if Applied to All Existing Elevators . . 370
182 Model Plant for New Feed Mills (Case 1 - Best Controls). . . . 377
183 Model Plant for New Feed Mills (Case 2 - Alternate Controls) . 378
184 Income Statement for New Model Feed Mill (1973) 380
185 Balance Sheet for New Model Feed Mill (1973) 381
186 Controls Applied to New Model Plant for Feed Mill 384
187 Variation in Control Costs by Size of Plant (Feed Mills) . . . 386
188 Air Pollution Controls on Existing Feed Mills (Survey of
402 Plants - 1972-1973) 387
189 Pollution Controls Applied to Existing Feed Mills 388
190 New Model Plant for Alfalfa Dehydration 392
191 Income Statement for New Model Alfalfa Dehydration Plant
(1972) 394
192 Balance Sheet for New Model Alfalfa Dehydration Plant
(1972) 395
193 Economic Impact of Controls Applied to New Model Alfalfa
Dehydrating Plant 397
194 Controls Applied to Existing Alfalfa Dehydration Plants. . . . 398
195 Model Plant for New Wheat Flour Milling (Case 1 - Best
Control) „ 401
196 Model Plant for New Wheat Flour Milling (Case 2 - Alternate
Controls) 402
197 Potential Positive Impact of Dust Control in Receiving and
Handling Sections of Model Flour Mill 405
198 Income Statement for New Model Flour Mill (1972) 406
199 Balance Sheet for New Model Flour Mill (1972) 407
200 Economic Impact of Controls Applied to New Model Flour Mill. . 410
201 Flour Milling - Pollution Controls of Existing Plants 412
202 Controls Applied to Existing Flour Mills ..... 413
203 Model Plant for Durum Flour Milling (Case 1 - Best Controls) . 416
204 Model Plant for New Durum Flour Milling (Case 2 -
Alternate Controls) „ 417
205 Economic Impact of Controls Applied to New Model Durum
Flour Mill 420
206 Model Plant for New Dry Corn Milling (Case 1 - Best
Controls) 423
207 Model Plant for New Dry Corn Milling (Case 2 - Alternate
Controls) 424
xx
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title
208 Potential Positive Impact of Dust Control in Receiving
and Handling Section of Model Dry Corn Mill 426
209 Economic Impact of Controls Applied to New Model
Dry Corn Mill 428
210 Dry Corn Milling Pollution Controls of Existing Plants . . . 429
211 Pollution Controls Applied to Existing Dry Corn Mills. . . . 430
212 Model New Plant for Rice Milling (Case 1 - Best Controls). . 433
213 Model New Plant for Rice Milling (Case 2 - Alternate
Controls) 434
214 ' Potential Positive Impact of Pollution Control in
Receiving and Storage Section of Model Rice Mill 436
215 Income Statement for New Model Rice Mill (1970) 437
216 Balance Sheet for New Model Rice Mill (1970) 438
217 Impact of Controls Applied to New Model Rice Mill. 439
218 Rice Mills, Pollution Controls on Existing Plants, Survey
of 26 Plants 441
219 Controls Applied to Existing Rice Mills 443
220 Model Plant for New Commercial Rice Dryer (Case 1 - Best
Controls) 446
221 Model Plant for New Commercial Rice Dryer (Case 2 -
Alternate Controls) 447
222 Potential Positive Impact of Pollution Control in Receiving,
Storage, and Loading Section of Model Rice Dryer 449
223 Income Statement for New Model Commercial Rice Dryer (1973). 451
224 Balance Sheet for New Model Commercial Rice Dryer (1973) . . 452
225 Impact of Controls Applied to New Model Plant 453
226 Controls Applied to Existing Rice Dryers 454
227 Model New Plant for Soybean Processing (Case 1 - Best
Controls) 456
228 Model New Plant for Soybean Processing (Case 2 -
Alternate Controls) 457
229 Income Statement for Model New Soybean Mill (1973) 459
230 Balance Sheet for Model New Soybean Mill (1973) 460
231 Economic Impact of Controls Applied to Model Soybean Mill. . 463
232 Pollution Controls of Existing Soybean Plants (Survey of
42 Plants) 465
233 Controls Applied to Existing .Soybean Processing Plants. . . 466
234 Model Plants for New Corn Wet Milling (Case 1 - Best
Controls). . 470
xxi
-------
TABLE OF CONTENTS (Continued)
List of Tables
Table Title
235 Model Plants for New Corn Wet Milling (Case 2 -
Alternate Controls) 471
236 Potential Positive Impact of Dust Control in Grain
Receiving, Cleaning, and Storage Section of Model Corn
Wet Milling Plant 474
237 Income Statement for New Model Corn Wet Mill (1970) 475
238 Balance Sheet for New Model Corn Wet Mill 478
239 Impact of Best Control Applied to Model New Corn Wet
Milling Plant 479
240 Wet Corn Mills, Pollution Controls on Existing Plants,
Survey of 13 Plants 481
241 Source Inspection Equipment 505
242 Source Inspection Field File 506
243 Air Pollution Control Devices Used in the Grain Processing
Industry 507
xxii
-------
TABLE OF CONTENTS (Continued)
List of Figures
Figure Title Page
1 Flow of Wheat From Farm to Market 9
2 Flow of Feed Grains From Farm to Market 10
3 Flow of Soybeans From Farm to Market 11
4 Geographical Distribution of Alfalfa Dehydrating Plants
(1972) 43
5 Diagram of Upright Country Elevator 112
6 Flow Diagram for Terminal Elevator 115
7 Schematic Diagram of Column and Rack Grain Dryers 133
8 Particle Size Distribution of Dust Entering Control System
Serving a Tunnel Belt Aspiration System (Grain
Elevator)„ 152
9 General Flow Diagram for a Feed Mill 156
10 Size Distribution of Particulate Emitted from Cyclone
Controlling a Horizontal Pellet Cooler (Feed Mill) . . . 165
11 Generalized Flow Diagram for Alfalfa Dehydrating Plant . . 170
12 Plant A Flow Diagram «, 172
13 Plant B Flow Diagram 173
14 Plant C Flow Diagram 174
15 Plant D Flow Diagram 175
16 Particulate Size Distribution, Alfalfa Dehydration,
Plant B 183
17 Particulate Size Distribution, Alfalfa Dehydration,
Plant C 184
18 Particulate Size Distribution, Alfalfa Dehydration,
Plant D 185
19 Simplified Flow Diagram of a Flour Mill 204
20 General Flow Diagram of a Corn Dry Milling Plant 217
21 Flow Diagram for Oat Mill (Cleaning House and Drying
System) 228
22 Flow Diagram for Oat Mill (Grading, Hulling and Finish-
ing) 229
23 Flow Diagram for Oat Mill (Cutting and Flaking Plant). . . 230
24 Flow Diagram for Rough Rice Receiving Section of a
Rice Mill 237
25 General Flow Diagram in a Combined White Rice and Parboil
Rice Mill 238
26 Flow Diagram for Rice Drying Facility 244
27 General Flow Diagram of a Soybean Processing Plant .... 246
28 General Flow Diagram for Oil Refining Section of a Soy-
bean Processing Plant. 249
xxiii
-------
TABLE OF CONTENTS (Continued)
List of Figures
Figure Title Page
29 General Flow Diagram for Corn Wet Milling Plant 257
30 Settling Chamber 279
31 Cyclone Dust Collectors 280
32 Typical Collection Efficiency Curves for High Throughput
and High Efficiency Cyclones 281
33 Recirculating Cyclonic Collector 282
34 Impeller Collector 283
35 Fabric Filter Configurations 285
36 Glass Mat Filter 287
37 High Velocity Filter 288
38 Boxcar Unloading Dust Control System 299
39 Dust Control System for Boxcar Loading 302
40 Hopper Car Loading Dust Control System 303
41 Diagrammatic Representation of a Bulk Carrier Hold .... 305
42 Diagrammatic Representation of a Tanker 306
43 Diagrammatic Representation of a "Tween Decker 307
44 Diagrammatic Representation of the Existing Air Exhaust
System at Pier 86, Seattle, Washington 311
45 Cyclone Collector - Equipment Cost Includes Basic Unit,
Dust Hopper, Scroll Outlet, Weather Cap and Support
Stand 318
46 Inertial Cyclonic Recycle Type-Equipment Cost Includes:
Basic Collector; Rotary Valve and Motor; Secondary Fan
and Motor 319
47 Fabric Filter - Equipment Cost Includes Basic Unit, Com-
plete With Air Pump and Rotary Valves, Motor, Starter. . 320
48 Wet Scrubber for Gaseous Pollutant Control - Equipment
Cost Includes Pump, Pump Motor, and Recycle piping. . . 321
49 Wet Scrubber for Gaseous and Particulate Control-Equipment
Cost Include: Basic Scrubber Stand; Piping; Recircula-
tion Pump; Control Panel; Fuse Connect; and Instrumenta-
tion 322
50 Impeller Scrubber-Equipment Cost Includes Scrubber,
Plumbing, Fan, Motor 323
51 Afterburner-Equipment Cost ..... 324
52 Model New Country Elevator--Best Controls 337
53 Model New Terminal Elevator (Inland)--Best Controls. . . . 338
54 Model New Terminal Elevator (Port)--Best Controls 339
55 Model Feed Mill—Best Controls 375
56 Model Alfalfa Dehydrating Plant—Best Controls „„.... 391
xxiv
-------
TABLE OF CONTENTS (Concluded)
List of Figures
Figure Title Page
57 Model Wheat Flour Mill—Best Controls 400
58 Model Durum Flour Mill—Best Controls 415
59 Model Dry Corn Mill—Best Controls 422
60 Model New Rice Mill (No Parboil)--Best Controls 432
61 Model New Commercial Rice Drying Plant—Best Controls. . . . 444
62 Model New Soybean Processing Plant 455
63 Simplified Flow Diagram of Corn Wet Milling Plant 468
64 Model New Corn Wet Milling Plant 469
65 Schematic of EPA Particulate Sampling Train 494
66 Common Particulate Sampling Trains 495
67 Sampling Point Location Layout ..... 497
68 Guide for Selecting Sampling Points 498
A-l Cut-Away Diagram of a Combine (Grain Harvester) 519
xxv
-------
SUMMARY
Activity in this program was directed to an analysis of the technical
and economic aspects of emissions control in the grain and feed industry.
The main objective of the study was to provide an improved technical and
economic basis which the Environmental Protection Agency could utilize to
formulate new source performance standards and other guidelines for emis-
sions control in the grain and feed industry. Industry structure and
statistics, the nature and sources of emissions, technical problems as-
sociated with emissions control, cost of dust control equipment, and the
overall economic impact of air pollution control were among the major
topics investigated in the program. The salient results of the program
are highlighted in the following sections.
INDUSTRY STRUCTURE
In the broadest sense the grain and feed industry could be defined to
include all the operations involved from the points where the raw materials
are grown (i.e., the farmer) to the points where all the final products are
prepared for sale or shipment to the consumer. For the purposes of this
study, however, a narrower scope of operations was considered. Specific
operations considered in this study were: (1) grain harvesting as it
relates to dust emissions in subsequent grain handling steps; (2) grain
elevators; (3) flour milling (i.e., wheat, durum, dry corn, rye, and oat);
(4) rice milling; (5) corn wet milling; (6) soybean processing; (7) com-
mercial rice drying; (8) alfalfa dehydration; and (9) feed mills. Ex-
cluded from this study were operations directly associated with the produc-
tion of items intended for human consumption (e.g., cereal preparation,
bread and bakery products, distilled alcoholic beverages).
In recent years, the cultivation, harvesting, transporting, and
processing of grains and grain products have been transformed from a pre-
dominately rural and semi-agricultural endeavor into a complex and vital
industry in the United States (i.e., the agribusiness industry). Operations
xxvi
-------
conducted in the grain and feed industry range from the relatively simple
harvesting, handling, and transporting of grain to storage facilities
(i.e., grain elevators) to the diverse, dynamic corn wet milling industry.
Chapter 2 presents a comprehensive discussion of the structure and statis-
tics of the individual segments of the grain and feed industry.
NATURE AND SOURCES OF ATMOSPHERIC EMISSIONS
There is a significant difference between atmospheric emissions
arising from grain and feed industry operations and those of other in-
dustries; namely, the majority of emissions are due to raw material handling
rather than raw material processing. Furthermore, some of the sources are
of a "fugitive" type. That is, the emissions are those that become air-
borne because of ineffectual or nonexistent hooding or pollutant contain-
ment systems rather than those that penetrate an air pollution control de-
vice. Other characteristics of emissions from the grain and feed industry
are the intermittent nature of many of the specific operations, and the
day-to-day variability of emissions from a specific operation.
The sources of atmospheric emissions from grain and feed plants can
be grouped into three broad categories: (1) grain handling, cleaning,
and storage; (2) grain processing; and (3) product handling and shipping.
Almost all grain and feed industry plants handle, clean, and store
grain as part of their operations. Unloading, conveying, weighing,
transferring and cleaning of grain are the individual steps involved in
the first category. There is a wide variation in the extent to which the
different plants in the grain and feed industry engage in these activities.
Grain dust, seeds, chaff, various types of pollens and mold spores, and
dirt comprise the main portion of the emissions from the first category of
sources.
The types of operations involved in the processing of grain in grain
and feed plants range from very simple mixing steps to complex processes
which are characteristic of industrial processing plants. Included are
such diverse processes as: (a) simple mixing processes in feed mills;
(b) dehydration in alfalfa dehydration plants; (c) grain milling in flour
mills; (d) solvent extracting in soybean processing plants; and (e) a com-
plex series of processing steps in a corn wet milling plant. Potential
atmospheric emissions from processing operations include hulls, bran,
flour, various ingredients used to manufacture feed, hexane vapor, and
various organic materials (e.g., acids, aldehydes).
xxvii
-------
Transfer and loading operations comprise the main steps in product
handling and shipping. Atmospheric emissions from these steps include
grain dust, finished feed materials, flour, soybean meal, and starch
particles.
Atmospheric emissions from grain and feed industry operations are
not considered to be toxic. They may cause irritation of skin or eyes,
and respiratory ailments can be caused by inhalation of particulates of
) no evidence exists for adverse effects to healthy people
from atmospheric emissions from grain and feed plants. However, people
having preexisting respiratory disorders may be affected or disabled by
rapid increases above the seasonal mean concentration of atmospheric emis-
sions from grain and feed plants. Chapter 3 and Appendix B discuss the
sources and nature of atmospheric emissions in more detail.
CONTROL TECHNOLOGY FOR ATMOSPHERIC EMISSIONS
Methods used for the control of dust emissions from grain and feed
operations consist of either extensive hooding and aspiration systems
leading to a dust collector or methods for eliminating emissions at the
source. The incentives for controlling emissions, in addition to complying
with air pollution regulations, include recovery of valuable materials,
sanitation, and reducing the fire and explosion hazards.
Where practical, techniques which eliminate the sources of dust emis-
sion or which retain it in the process are the most effective. These tech-
niques may require enclosures or covers on bins, tanks, and hoppers, and
the replacement of worn-out parts. Emissions can also be eliminated by
minimizing the number and size of openings, and maintaining the system's
internal pressure below the external pressure; thus air flows into, rather
than out of, the openings. When the methods for eliminating the sources
of dust emission are not practical, systems are used which capture the
dust as it is entrained or suspended in the air, and convey it to a dust
collection device.
Adequate design of the emission containment or hooding system is vital
for effective air pollution control in grain and feed plants and in most
cases the system must be individually tailored for each process. Grain
unloading, loading, and drying operations represent some of the more dif-
ficult sources for proper dust pick-up, whereas for most other sources the
design of the emission containment system is essentially straightforward.
xxviii
-------
Cyclone collectors, fabric filters and wet scrubbers are used to con-
trol emissions from the various grain handling and processing sources.
Wet scrubbers have not found wide application because of the associated
water pollution potential and because they do not permit direct recycling
of the collected material. Due to tightening emission control regulations,
fabric filters are now being used on many sources which were formerly con-
trolled by only low efficiency mechanical collectors. High efficiency
mechanical collectors are being used on several processes, where the high
moisture content of the effluent streams or other process requirements
preclude the use of fabric filters.
The fairly dry nature of the dust generated in grain and feed plants,
the low temperatures involved, and the relatively large particle size of
the dust make cyclone collectors and fabric filters effective for most
sources of atmospheric emissions. A variety of these devices have been
installed, ranging from single large diameter cyclones to reverse-air
fabric filters. Screens have also been used for such unique applications
as reducing the emission of large-sized particles (beeswing) from grain
drying operations. Grain dryers present a difficult problem for air pol-
lution control because of the large volumes of air exhausted from the
dryer, the large cross-sectional area of the exhaust, the low specific
gravity of the emitted dust, and the high moisture content of the exhaust
stream.
With one or two exceptions, control system technology is available
for all sources of atmospheric emissions in grain and feed plants. Grain
drying and barge and ship loading operations are the major exceptions.
Recent work on the control of dust emissions from ship loading operations
shows promise of resulting in significant reduction of emissions from
those operations. While fabric filter systems are the most efficient
dust collectors for a majority of the sources of atmospheric emissions,
operational problems (e.g., blinding of the fabric) sometimes occur when
grains of high moisture content are being handled. Fabric filter systems
on grain receiving pits are especially prone to operational problems when
wet grains are received at grain elevators.
The characteristics of the various types of control devices suitable
for use on emission sources in grain and feed processing operations are
discussed in detail in Chapter 4.
xxix
-------
COST OF DUST CONTROL EQUIPMENT
The total installed cost of dust control equipment for a given source
in grain and feed plants is highly variable depending upon such factors as:
Type of installation, new or existing plant;
Type of labor used, plant or contract labor; and
Type of process controlled; amount of ductwork required; and
geographical location.
Existing plants may have much of the hooding systems and ductwork
already installed and require only the installation of a new control de-
vice and fan. Thus the total installed cost for upgrading the controls
on such a facility might be less than for a new plant. On the other hand,
such factors as space limitations, the necessity of working around existing
process equipment, and providing additional structural support for the dust
collectors, increase the total installed cost. In general, the cost to a
new plant, where the control system is an integral part of the plant de-
sign, is less expensive than the control cost for older plants. Because
of the large variability in costs, the cost to control an individual
facility must be determined by careful evaluation of the particular re-
quirements of that facility.
Approximate cost ranges for controlling specific types of emission
sources are:
1. Grain handling $1.50 - 4.00/cfm
2. Grain milling $1.50 - 3.00/cfm
3. Grain drying $0.25 - 0.75/cfm
4. Pellet coolers $1.20 - 3.00/cfm
5. Germ, feed and gluten
drying $2.00 - 5.00/cfm
6. Soybean meal drying $2.00 - 6.00/cfm
The preceding figures represent only the normal cost range, which
would be applicable to perhaps 90% of the various source types. There
are, however, installations which may cost twice the high value in each
xxx
-------
range because of circumstances peculiar to that installation. Additional
information on the costs of control equipment is presented in Chapter 4.
ECONOMIC IMPACT OF DUST CONTROL
The initial intent of the analysis was to determine the economic im-
pact of. dust control systems only for new facilities in accordance with
the directives of the Clean Air Act of 1970. However, since there are few
new facilities being constructed when compared to the number of existing
facilities in the grain and feed industry, the long-term economic impact
of air pollution control regulations in this industry will be borne by
existing facilities. In order to accurately reflect the probable economic
impact of air pollution control regulations, the analysis was expanded to
include both new and existing facilities.
A series of plant financial models was used to perform the analysis
of the economic impact. Separate models were developed for each type of
plant within the grain and feed industry, and in some cases, for various
sizes of operations within each industry segment. The capacities, handling
rates, operating hours, and other items listed in the individual plant
specifications were selected to represent average or medium-size plants in
most instances. The model plant is representative of the particular in-
dustry; however, it is not meant to represent the total industry. In each
industry segment there are significant variations in the size, configuration
and operating characteristics of different facilities. These variations
will affect the economic impact which air pollution control requirements
will have on specific facilities.
The limited scope of the present study barred a detailed parametric
study of the economic impact as a function of plant size and configuration,
and the model plants used in the analysis only present a simplified flow
diagram for each type of facility. As a consequence, there are some weak-
nesses and shortcomings in the model plant concept. For example, it was
not possible to incorporate variable factors such as:
1. Product mix between plants and within a plant;
2. Alternative processing techniques and equipment selection; and
3. Plant site and layout.
xxxi
-------
Because of the limitations imposed by the model plant approach, the results
of the economic impact analysis should be viewed as indicative of the
probable economic impact and not the absolute impact.
The economic impact analysis was performed for two distinct cases of
dust control in each industry category:
Case 1 - Installation of the best demonstrated control system cur-
rently available for each specific source.
Case 2 - Installation of control systems that generally reflect cur-
rent industry practices.
The dust control equipment selected for individual emission sources
in Case 1 represented MRI's judgment of the "best" demonstrated control
system currently available for the specific source. Selections of dust
control equipment for Case 2 were based on the understanding of industry
practice obtained during the course of the program. In general, cyclone
collectors were selected in Case 2 except for those sources where industry
practice (e.g., fabric filters being used in the mill house of a flour mill)
indicated that fabric filter systems were generally being used to improve
recovery of intermediate or final products. In selecting the dust control
equipment for Cases 1 and 2, consideration was not given to the need to
comply with any specific air pollution regulation.
The economic impact of new source performance standards on the grain
and feed industry will be different for the various industry segments. In
general, the impact on industry resulting from new plant regulations will
be small, if for no other reason than few new plants are being built. The
industries such as country elevators and feed mills, which have a lower
initial investment cost for total plant and equipment, will be affected
more severely than industries such as soybean processing and corn wet
milling, which have relatively greater investment requirements for a new
plant.
Requirements for pollution control equipment on new plants will in-
crease the economies of scale within most of the industries in the grain
and feed sector. The investment and annual operating costs for pollution
control equipment required on grain handling operations will be essentially
the same for plants of the same design, regardless of size. The type and
size of control equipment are dependent upon the operations required in
receiving, handling and shipping grain rather than upon the volume of grain.
xxxii
-------
For example, a truck or rail receiving station at the plant will require
the same basic control device and cubic feet per minute, regardless of
the number of trucks or cars which are unloaded during the year. As a
result, in most of the grain and feed industries, the larger plants will
tend to be more economical than smaller ones.
For all of the new model plants, the annual operating costs, including
electrical charges, maintenance expenses, depreciation expenses and capital
charges, were estimated for each pollution control system. For each model
plant, a summary of the annual operating costs for the two alternative con-
trol systems is given below. The annual control costs are compared to the
model plant's net income before taxes.
Annual Costs of Pollution Control Equipment
for New Model Plants
Case 1
Case 2
Industry Segment
Country elevators
Inland terminals
Port terminals
Feed mills
Alfalfa dehydration
Wheat flour mills
Durum flour mills
Dry corn mills
Rice milling
Rice drying
Soybean processing
Corn wet milling
Annual
Control
Costs ($)
17,642
75,238
96,209
44,035
12,570
98,730
154,210
117,820
89,550
19,790
155,650
277,090
Percent of
Net Income
62.7
31.6
19.4
20.9
23.
23.
36.
28.
.3
.5
.7
.1
16.6
35.5
10.6
11.2
Annual
Control
Costs ($)
14,623
57,238
71,490
35,610
11,123
79,610
128,850
99,970
65,190
19,750
130,550
264,110
Percent of
Net Income
51.8
24.0
14.5
16.8
20.7
19.1
30.7
23.8
12.1
30.0
8.9
10.4
Investment in best available control equipment for new plants amounts
to approximately 15 to 18% of the total investment in plant and equipment
for country elevators, feed mills, alfalfa dehydration plants and wheat,
dry corn and rice mills. The percentage is smaller for other industries
dropping to approximately 3% for corn wet mills and port terminal elevators,
xxxiii
-------
The alternate control equipment specified for each model plant gen-
erally reduced the investment costs required for best controls by 15 to 20%,
The investment required in control equipment for each of the new model
plants analyzed in this study is presented below.
Investment in Control Equipment
for New Model Plants
Industry Segment
Country elevators
Inland terminals
Port terminals
Feed mills
Alfalfa dehydration
Wheat flour mills
Durum flour mills
Dry corn mills
Rice mills
Rice drying
Soybean processing
Corn wet milling
Case
Investment
for Control
Equipment ($)
94,040
354,720
444,830
196,370
54,800
330,030
458,030
430,260
348,640
102,940
528,250
871,900
1
Percent of
Total Plant
Investment
16.4
5.9
3.0
16.8
17.9
14.0
18.3
17.2
15.4
9.6
7.8
2.9
Case
Investment
for Control
Equipment ($)
80,262
286,030
355,140
158,680
48,550
264,340
371,340
373,970
260,130
89,013
439,760
827,250
2
Percent of
Total Plant
Investment
14.0
4.8
2.4
13.6
15.8
11.3
14.9
15.0
11.5
8.3
6.5
2.7
In most of the model plants, particularly those with milling or grind-
ing operations, some of the equipment required for pollution control also
serve as product recovery devices and as such, should not be classified
solely as a pollution control cost.
For the plants analyzed, particularly those which handle or process
grain, there are a number of control credits or positive impacts which
will result from the installation of pollution control equipment. These
positive impacts include:
1. Reduction in product shrink (i.e., recovery of product),
2. Reduction of maintenance costs through savings on lubricants and
similar materials.
xxxiv
-------
3. Increased life of protective coatings,
4. Labor savings in plant clean-up,
5. Reduction in fire insurance premiums for stocks, property and
business interruptions, and
6. Tighter insect and rodent control with attendant reduction in
grain losses.
The only control credit which was quantified in the model plant
analyses was the reduction in product shrink. A dollar value was assigned
to the dust which would be collected from the plant's operation. In most
cases, the material collected by pollution control devices has some value.
For some of the control devices—particularly on the processing operations-
the recovered material can economically justify their installation. The
larger the plant, the more likely it is that pollution control equipment
can be economically justified.
The economic analysis was extended to determine the impact of instal-
ling pollution control equipment on an average existing plant. These ex-
tensions allowed for (1) the increased costs to install control equipment
on existing plants, and (2) pollution control equipment which is already
installed based on plant surveys conducted as part of the study. The in-
vestment and annual operating costs for existing plants were used to esti-
mate the total costs to the industry. Because of the number of existing
plants, the greater impact would be on the country elevator and feed mill
industries.
The annual operating and investment costs for installing control
equipment on all existing plants is summarized below.
xxxv
-------
Pollution Controls Applied to Existing Plants
Total Annual
Operating Total Investment
Cost for Industry Costs for Industry
Case 1 Case 2 Case 1 Case 2
Industry Segment ($000) ($000) ($000) ($000)
Country elevators 150,659 105,561 835,942 603,064
Inland terminals 31,892 21,564 151,958 114,235
Port terminals 5,922 1,779 26,897 19,781
Feed mills 205,000 134,400 1,042,000 673,000
Alfalfa dehydration 2,765 2,447 12,792 11,333
Wheat flour mills 15,375 8,075 75,000 40,371
Dry corn mills 8,100 3,900 39,700 21,500
Rice mills 3,157 1,299 14,376 5,640
Rice drying 34,500 29,800 34,500 5,600
Soybean processing 11,388 6,357 46,670 29,900
In general, plants within the grain and feed industry will be able
to pass on, rather than absorb, the increased costs from pollution controls,
The increase in prices which would result from pollution controls are
small when compared to general price increases of commodities within the
industry since 1972. Some of the small plants which would have cost in-
creases from pollution control above the average per unit cost for com-
peting plants may have to absorb the control costs.
The installation of pollution controls will not affect the industry
structure of industries such as corn wet milling, port terminal elevators
and soybean processing which have relatively large plants and a small
number of companies. However, industries, particularly country elevators
and feed mills, which have a large number of firms with small plants will
be affected. Small independent firms will be less likely to have the
necessary capital to build and operate new plants.
EPISODE PROCEDURES, SOURCE SURVEILLANCE AND MONITORING, AND FIELD SUR-
VEILLANCE AND ENFORCEMENT
Episode procedures, techniques for source surveillance and monitoring,
and general practices for field surveillance of air pollution sources and
enforcement of regulations as they pertain to the grain and feed industry
were analyzed in this program.
xxxvi
-------
In general the strategies to control emissions from grain and feed
plants during air pollution episodes parallel those developed for other
industries. The methods of reducing ambient air concentrations caused by
grain and feed plants generally consist of curtailing, postponing, or
deferring production and operations. Due to the close relationship between
various processes in some grain and feed plants, any curtailment in one
process will inevitably result in some curtailment of another process.
The exact plan to be implemented at any given facility will depend on the
process layout and material flow, storage capacities at critical points in
the process flow, steam and/or heating requirements, and the degree of
existing control on a specific process.
Emission control actions for emergency situations might present some
problems for the grain and feed industry. Foremost among the potential
problems is the spoilage of raw grains. Corn, soybeans, and other high
moisture content grains are dried soon after receipt to prevent deteriora-
tion. Thus, spoilage could occur if drying operations are curtailed for
more than a day or so. A similar risk applies to grain which must be kept
in trucks, railroad cars, or barges due to curtailment of receiving opera-
tions. The length of time that a shipment can be stored without drying
will vary widely with the moisture content, ambient temperature, and degree
of bacterial infestation.
With the exception of grain drying operations, the large majority of
grain handling and processing emission sources can be sampled by existing
procedures. The EPA Method 5 procedures and particulate sampling train
are well suited for use in the surveillance of emission sources at grain
and feed plants. Grain dryers present unique sampling problems because
of inaccessibility, large exit surface area, low gas velocities, and large
particle size of the emitted particulate. Both EPA Method 5 and Hi-Vol
sampling procedures have been used to test emissions from grain dryers. At
present, no ideal sampling train exists for this application.
Recommended field surveillance and enforcement procedures for grain
and feed plants parallel those developed for other industries. Chapter 8
discusses the recommended procedures at some length.
RECOMMENDATIONS FOR FUTURE PROGRAMS
The most important areas where additional research appears warranted
can be grouped into the following categories:
xxxvii
-------
1. Dust control systems
2. Source testing methods
3. Emission factors
4. Health and welfare effects
Only those sources which involve the generation of fugitive dust
(e.g., grain receiving and loading and product unloading) and some drying
or dehydrating operations present problems where additional control tech-
nology development would seem justified. Containment of the fugitive dust
is the principal problem with regard to the former group of sources. The
properties of the effluent stream pose the major difficulties for control
of the emissions from drying operations.
Grain dryers present unique sampling problems. No reliable sampling
train exists for this application. A program to upgrade sampling procedures
for grain dryers is recommended.
Limited data are available on emission factors for uncontrolled sources
in the grain and feed industry. To evaluate accurately either the environ-
mental or economic impact of air pollution control regulations on the
various segments of the grain and feed industry, the emission factors for
each major pollution source should be known. A program to develop emis-
sion factors for all major sources of emissions is recommended.
A program is also recommended to further define the effect of airborne
emissions from grain and feed industry operations on human health and
welfare. Attention should be focused on synergistic effects produced by
interaction with other particulate or gaseous components of atmospheric
pollution.
xxxviii
-------
CHAPTER 1
INTRODUCTION
PURPOSE OF THE STUDY
The Clean Air Act of 1970 expanded the responsibilities of the Environ-
mental Protection Agency to include the establishment of new performance
standards for new stationary sources, the delineation of best emission reduc-
tion systems that have been adequately demonstrated for use on various sources,
the assessment of the economic impact on U.S. industry of the new performance
standards, and the development and promulgation of inspection and monitoring
procedures to assure compliance with the new performance standards. To carry
out these and other responsibilities, the Environmental Protection Agency has
to: (1) ascertain the present status of emissions control in various indus-
tries; (2) assess current costs for pollution control equipment; (3) determine
what additional progress could be expected by the application of existing or
nearly-developed technology; and (4) define areas of research and development
necessary for further advances in the control of air pollutants.
This study of the grain and feed industry was conducted to provide an
improved technological and economic basis which the Environmental Protection
Agency could utilize to formulate new performance standards and other guide-
lines for air pollution control in the grain and feed industry. The study
comprised a review of processing operations, an analysis of the nature and
sources of emissions from various processing operations, a comprehensive and
systematic evaluation of the technical and economic problems associated with
the control of dust emissions, a review of source and ambient air sampling and
analysis techniques, and an evaluation of the overall economic impacts of air
pollution control in the grain and feed industry.
SCOPE OF STUDY
In the broadest sense the grain and feed industry could be defined to
include all the operations involved from the point where the raw materials are
grown (i.e., the farm) to the points where the final products are prepared for
shipment to the consumer. For the purposes of this study, however, a narrower
scope of operations was considered. Specific operations considered in this
study were: (1) grain harvesting as it relates to dust emissions in sub-
sequent grain handling steps; (2) grain elevators; (3) feed mills; (4) alfalfa
-------
dehydration; (5) grain milling (i.e., wheat, durum, dry corn, rye, and oat);
(6) commercial rice drying; (7) rice milling; (8) soybean processing; and (9)
corn wet milling. Excluded from this study were operations directly associ-
ated with the production of items intended for human consumption (e.g.,
cereal preparation, bread and bakery products, distilled alcoholic beverages).
ORGANIZATION OF THE STUDY
The study was divided into three major phases. The first phase involved
the gathering, compiling, and analysis of information concerning the techni-
cal, economic, and operational aspects of facilities in the grain and feed
industry. Literature reviews, emissions inventory questionnaires, discus-
sions with industry trade associations and individual companies in the in-
dustry, site visits, and discussions with equipment manufacturers (both
process and dust control) were used to gather the information.
Approximately 2,300 emissions inventory questionnaires, requesting data
on grain handling and processing procedures, dust control equipment perfor-
mance and cost, and dust emission rates, were sent to various plants in the
grain and feed industry. Table 1 presents a breakdown of the response to the
questionnaires. Appendix C contains a sample of an emissions inventory
questionnaire.
Table 1. RESPONSE TO EMISSIONS INVENTORY QUESTIONNAIRE
BY GRAIN AND FEED INDUSTRY FIRMS
Industry Segment Questionnaires Mailed Responses
Grain elevators 625 509
Grain milling (wheat, durum,
dry corn, rye, rice,oats) 706
Soybean processing 121
Corn wet milling 15
Feed mills 630
Alfalfa dehydration 237
2,334 2,021
Overall response - 87%
MRI, PEDCo-Environmental and EPA personnel visited over 100 individual
facilities during the course of the program to observe directly the nature
of operations in various segments of the grain and feed industry. During these
site visits, discussions with plant supervisors and operating personnel provided
-------
valuable insight into the many factors that contribute to dust emissions
from grain handling and processing equipment.
Information obtained from the emissions inventory questionnaires and
site visits was used to compile data on locations, types, and capacities of
facilities, plant operating parameters, dust control systems and techniques,
dust control equipment performance, costs of dust control equipment, and
current status and capabilities of source sampling, monitoring, and analyti-
cal techniques for air pollutants.
The second phase focused on a thorough evaluation of the technical and
economic problems associated with the control of dust emissions in the grain
and feed industry. Current control practice and the best systems for emis-
sion reduction for each major source of dust were identified. By using a
modeling technique based on flow diagrams for model plants, the cost and
effectiveness of best emission reduction systems (fabric filters in most
cases) were evaluated for individual facilities. The financial impact of
equipping plants with the best emission reduction system was then analyzed
for individual plants and for the entire grain and feed industry. A limited
analysis of the economic impact of equipping selected emission sources in
grain and feed industry plants with cyclone collectors was also conducted.
The final phase of the study was the identification of gaps in technol-
ogy and the development of recommendations for needed research and develop-
ment efforts to solve air pollution problems in the grain and feed industry.
In the following chapters of this report, we present a general descrip-
tion of the grain and feed industry (Chapter 2), processes and emissions
(Chapter 3), dust control technology and associated costs (Chapter 4), anal-
ysis of financial impact of dust control efforts (Chapter 5), air pollution
episode procedures and source surveillance methods (Chapters 6 and 7), field
surveillance and enforcement (Chapter 8) and research and development recom-
mendations (Chapter 9).
-------
CHAPTER 2
INDUSTRY STATISTICS
INTRODUCTION
A general description of grain production and utilization in the grain
and feed industry along with information on the structure and other charac-
teristics of the grain and feed industry is presented in this chapter. The
development and growth of the industry, types of business organizations in-
volved in various segments, and the number and location of facilities are
among the subjects discussed in the following sections.
GRAIN PRODUCTION
Grain Production and Utilization
Grains are the primary raw materials for some of the industry segments--
grain elevators, grain milling, rice milling, and corn wet milling--studied
in this program. In addition, feed mills use grain and grain by-products as
raw materials. Soybeans and alfalfa, which are not classified as grains, are
raw materials for the soybean processing and alfalfa dehydrating industries,
respectively.
Trends in the production of feed grains (corn, oats, barley, and sorghum
grains); food grains (wheat, rice and rye); and soybeans are shown in Table 2.
Corn is the largest crop with approximately three times the quantity of wheat--
the second largest crop. Soybeans now rank third in quantity of production
and second in cash value.* Soybeans have shown the most significant increase
in production over the past 30 years; increasing from 79 million bushels in
1940 to 1,124 million in 1970. Oats is the only crop which has significantly
declined in production during this time.
Not all the grain that is harvested is sold from the farm. Substantial
portions of some crops are retained on the farms for use as livestock feed
and seed. Table 3 shows the quantities sold from farms for the major grains
and soybeans. In 1971, 57% of the feed grains, 947., of the food grains, and
* Soybeans are actually classified as an oil seed and not as a grain.
4
-------
"^.
M
•^1
05
o
Ot
o
^3
r^
rXj
O
x3
o
M
H
U
* — i
Q
O
PC;
PM
0
w
1
>
>H
H
r-l
H
25
^
4-)
•r-l
4-1 ,-v
C 3
CO J3
3
0- 0
o
a o
0 •
•i-l O
•U O
o o
3 N-<
T3
O
PM
ON C^ "d" VO
f *l O^ P^ CM ON
r-» o co i— i vo
ON « » •>
rH «* r-l i-l
S S §R
vO O CO 00 vO
ON * rt
rH «tf r-l
ssss
O O> t*) iA vO
o> ^ *
i—* CO r-H
CO ^O *«^* CO
to r^> co r^ ^f
m oo o\ co CM
CTt ^
i-< •<]• VO r— (
VO O CO CM
co co
#\
rH
Sf 1^- OO O i— 1 •<)" O
• -r-l CO rH 0)
to
B
t>0
co o
C to
CO >-,
4J ^C04Jr4CJCU
OjflOJ-icflcO'H^,
OgwoOMaJoi
-------
U
^
v—1
J
o
S
0
M
H
CO
O
PH
CO
M
Q ,-v
3
& X)
< 0
ta o
Q °
58
O
O N~'
PRODUCTl
CO
01
*2
CO
H
1
O
VO
O
ON
r-4
6
o
J_J
pT| £
t-i
T) CO
O
CO
r>» r~» m
r~~ oo co
r»- CM m
-
i-H i— 1
C
O
•H
4-1
U
3
-0
0
B
o
r-l
fH 3
TJ CO
O
CO
<}• m in
i-i in m
co co m
* ^
r-~ CM CM
co r^ o
CM CM T-I
CM r-l r-l
O
4j
O
3
•O
O
Pn
^f\ CD "*^"
o\ r*"s c\i
O CO i-l
•t *k *
-------
987o of the soybeans were sold from farms. This is equivalent to approximately
212 million tons.
The supply and distribution of grain for the crop year 1971 are shown
in Table 4. The supply of grains is from carryover, production or imports
and the distribution or utilization is classified as feed, seed, food and
industrial, or export. Exports include the grain equivalent of products
(i.e., the grain may first be processed before being exported). The dis-
tribution classifications in Table 4 also include the quantities of grains
retained on farms for use as feed and seed.
The use of corn for feed is the largest single use of grains. Of a
total grain production of 10.6 billion bushels in 1971, approximately 37%
is accounted for by corn used for feed. The portion of a crop used for
seed is only 27° or less.
Industrial processing of grain accounts for only a small percentage
of the total utilization. Industrial uses of grain products include: (a)
cornstarch in paper and textile manufacture; (b) adhesives made from dex-
trin; (c) soybean oil in the manufacture of paint; and (d) the use of grain
flours in foundries as a core binder.
The food value of grain greatly exceeds its value for industrial uses.
Wheat is the most important crop for human consumption, although its use
for livestock feed has increased from 37o of total production in 1960 to 167»
in 1971. Rice sold from farms is used entirely for human consumption; how-
ever, a part of this is an indirect consumption of rice used in breweries.
The use of corn for human consumption is predominately in the whole form
(canned and ear corn), as cereals, as hominy, and as cornmeal. Corn flour
is not used as much as wheat flour and only about 1070 of dry-milled corn
which goes to human consumption is ground into flour.
The export market has become an extremely important one since World .
War II. Wheat exports have amounted to as much as half the wheat harvest
in some years. Soybean exports have been one of the more spectacular de-
velopments in American agriculture in recent years. From a prewar situa-
tion in which the United States imported soybeans, this country now provides
over 907o of the soybeans entering the world market.—
Grain Movement
Figures 1, 2, and 3 show the flow of grain from farm to market for wheat,
feed grains, and soybeans. Although the percentages in these figures are
based on the 1963-64 crop year, they are still generally representative of
the patterns of grain movement.
-------
^1
CO
•
CD
•S
CO
a
M
2
*~^l
rQ |
fa i— 1
O r-.
ON
Sol?
H 13 ^
|Z> H
pa a o
nag
Oi M 0
H Q
co H o
s Ǥ
P5
^c
2 w
<; PH
rJ
(X,
PH
CO
•
^r
cu
i~H
rrt
H
C
O
•H
4J
3
rO
, 1
•r~l
t-i
4-1
CO
•r-l
Q
^
r-l
a
ex
3
CO
(U
CO
i— i
CO
4-1
O
H
in r^» co
•^
r-l
t—l
ON
*
1^,
r-4
CO
-a -i-i
C rJ
CO 4-1
CO
T3 3
O T3
o a
r^ VD m o CM ro oo
O CM CO rH O -d"
. CM
ON
m
oo
rt
m
i
i^ ij
(-1 CU
CO K*
U 0
CO i— 1 ON i— 1 CM vD 00
vO CO ON ON i— 1 in CM
vo r*. m i— i
0
00
CN
**
CM
e
3
t-C
bO r-t
S-i co
CO O 4J
-^. C! co o
co| ca >, H
c
•H
CO
O
4J cu c cu
C CO J3 -i-l CO r-l
t-l CU >N CO 4-1 M CU
O _C O S-i cfl to >N
o § co o o pa Pi
*
cu
r^"
•o
C
CO
+,
cu
71
CO
^ o
«s
co
4-1
CO
O
4^
CO
CU
*5
(-1
O
IH
cu
C
3
i
>>
t ^
3
k"
4
r4
O
Cfl
C
•r-l CO
cfl C
I-i O
6D -i-l
4-1
C ^o
CO •!-!
^
CO • 4-1
C CO CO
CO 4-1 -i-l
CU O T3
^fN 3
>, ID r-l
O O CO
CO (-1 -1-1
OH ^
" 4J
C M-l CO
l-i O 3
O TJ
O 4J C
d -H
rl CU
O «-l T3
4-1 co C
> co
CU 3 T3
ja cr O
6 Q) 0
0) M-l
4-1 C
0) TO 4-J
Cfl J-l M-l
60 &
I
CO T3
>-l CU CU
CU *O *TD
rO 3 3
O rH i-l
4-1 0 0
0 C C
O M M
^ «-v^ •»^
COl rO| 0|
-------
«b
0)
S
o
to
1-1
B
o
(-1
4J
flj
0)
60
•H
Cn
-------
OJ
A!
o
4J
Cfl
14-J
rt
M
60
a)
OJ
§
CM
a)
60
•I-l
10
-------
"A
O
j-1
e
4-1
CO
a
a
0)
,£>
>>
o
CO
<4-l
O
!S
O
ro
0)
I
v-l
11
-------
Based on the figures, approximately 85% of the grain sold from farms is
handled by country elevators before being shipped to terminal elevators or
grain processors. However, as a general trend, larger volumes of grain are
bypassing country elevators as a result of improved roads, larger trucks, and
increased on-farm storage facilities which encourage the movement of grain to
more distant subterminal or terminal elevators and directly to processors.
Country elevators ship 92% of their wheat and 87% of their soybeans to
subterminal or terminal elevators. Only 56% of the feed grains are shipped
through these terminal markets. The remaining 44% of the feed grains handled
by country elevators are shipped directly to processors--primarily feedlots.
Terminal Markets
Grain being transported to market is channeled to towns and cities in
which storage capacity has been built up over the years. These cities are
typically metropolitan centers in the agricultural areas of the nation. A
list of grain-trading centers with volumes of inspected grain receipts and
shipments for the year 1970 is shown in Table 5.— Minneapolis and Duluth
ranked first and second in volume of grain handled during that year. Listed
in the top 10 cities are the comparatively small cities of Hutchinson, Kansas;
and Enid, Oklahoma, which are located in the most productive wheat growing re-
gion in the nation. These data are from grain exchanges and boards of trade
in these cities, and do not include grain not marketed through these organi-
zations. In some cities, a considerable amount of grain bypasses the commod-
ity exchanges. In Peoria, Illinois, for example, only 27 million bushels of
grain, all rail receipts, were received through the Peoria Board of Trade;
however, 117 million bushels were shipped out—all by barge, under Board
aegis. The difference is in the amount of grain driven in trucks directly
to barges or to elevators.
The data in Table 5 show the importance of truck transportation at the
producing end of grain's farm-to-market journey. Toledo and Indianapolis
receive more grain by truck than by rail. In Toledo, truck receipts in 1970
exceeded rail receipts by a ratio of approximately 5 to 1. The amount of
truck receipts in Chicago, is nearly three-fourths of the amount of rail re-
ceipts. Truck shipments from terminal markets, however, are less than rail
and water shipments. Where water transportation is available, such as the
Missouri-Mississippi and the Illinois rivers, shipment by barge is important.
However, railroads haul the largest ton-mileage.
The importance of barge traffic in the Midwest is indicated by the barge
receipts at New Orleans. In 1966, when the Port of New Orleans exported
nearly 500 million bushels of grain (see Table 6), over 200 million bushels
of corn were shipped from various towns on the Illinois River in the down-
river direction.—
12
-------
Q
ON
, — |
Cfl
W
3
a
M
H
H
Cfl
H
PH
h~1
w
o
u
Pi
a
H
2
o
0)
r-l
to
H
T)
cx Is
p.t ^Q
j
•rl
JS 0
cfl O
O
e '
•i-l O
CO O
M O
O "- <
t)
CO <->
> 3
•H rO
CJ O
co o
Pi O
«t
C O
•r-t O
CO O
I-l ^
o
1— 1
O CM r-l 1-4 r-l
H
col m| 4:1
Ml CO O O ir> CM
|J C CN ** -I
PQl
O to ro
3 C
H
i— 1 CO 1—41 —
•r-f C 0 1-1
CO r-l
Pi
r-l
4J O "d° CN O> QO
O *^ C^J CM i—4 r— 4
H
col ~«| ^o|
Ed r-i
U CO O 00 LO i-l
3 fi 00 CM p»
H
3 S S S § £
to i— I i— 1 r-l
cfl to
4-1 T-I C!
O M CO
co 3 -i-l
Q) O M
§CO CO CO -r-l
4J W -i-l 3
•r-l O -ft O O
*>*t CO ^ £J j_J]
CO -H
« fl » r-4 »
i— 1 a -H Cfl
0 O - CO
CX •> O r-l
CO ,d CO 60 VJ
C 3 co o
silSI
i—l CM CO -rf 1T1
tOCM^CNJCM^CO 9 g g g^^^J
i—4
^oi
o3cn CSci,o4->eH
co "ji «s; "T-icOQ)a.-i-io
C! "COO t03,^cocoO4-i «
•H O r-4 iH"4JO3OC COCO
O CO CJ ^T MH J3 J- ? -i-l 3 >'}-!
i 2 3 1 1 1 s s s s s i S 1
'Ot^-OOONOr-ICMC'l ^tO^Ol^-QOON
CO
r-4 •
a)
• co
£ S
C > •
o co
CO r-l
CO Jil rO
i—I cfl co
CO r-l r-l
CO -i-l
CO CO CO
to co >
^ *"O flfl
CO r-l 4J
J
-------
Table 6. FREIGHT TRAFFIC IN PORT TERMINALS, FOREIGN
EXPORTS AND COASTWIDE SHIPMENTS^/
Amount of Grain Loaded
Port
New Orleans, Louisiana
Houston, Texas
Duluth-Superior, Minnesota
Portland, Oregon
Galveston, Texas
Corpus Christi, Texas
Chicago, Illinois
Pascagoula, Mississippi
Beaumont, Texas
Baltimore, Maryland
Toledo, Ohio
Norfolk, Virginia
Seattle-Tacoma , Washington
Longview, Washington
Mobile, Alabama
Long Beach, California
Philadelphia, Pennsylvania
Milwaukee, Wisconsin
Kalama, Washington
Lake Charles, Louisiana
Albany, New York
Sacramento, California
Brownsville, Texas
Charleston, South Carolina
Orange, Texas
1966
Rank
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
1966
(000,000 bu)
496
218
212
123
111
104
98
87
78
64
62
61
44
42
40
39
33
23
21
19
15
11
10
9
5
1971
Rank
1
2
3
5
11
8
6
15
7
13
4
10
9
12
18
23
14
19
16
21
22
17
20
24
25
1971
(000,000 bu)
463
312
175
85
35
52
70
21
62
24
86
39
40
25
16
4
24
16
21
13
5
19
15
4
2
14
-------
Some terminal markets function as distribution centers by shipping out
most of the grain received. In Enid, Oklahoma, shipments in 1970 exceeded
receipts by about 3 million bushels. This difference was made up from grain
held in storage from previous harvests. Other terminal markets where ship-
ments are much less than receipts are processing centers where grain is de-
livered to various processing plants. For example, Buffalo, New York,
processes nearly all the grain received into flour before it is shipped.
Kansas City is both a distribution center and a processing center. Of 222
million bushels received in Kansas City in 1970, 124 million were shipped
on to other points; however, about 100 million bushels, or 4570 of the receipts,
were retained for processing.
Also of importance as grain handling centers are the seaports at which
grain is loaded for export. Table 6 lists seaports where grain is a major
export item. Over 50% of exports were from ports on the Gulf of Mexico in
1966 and 1971. In both years, New Orleans was the most important grain ex-
port center. At some ports, one grain accounts for nearly all of the ship-
ments. For example, Lake Charles, Louisiana, ships mostly rice; while grain
sorghums (milo) make up most of the grain shipments from Corpus Christi.
GRAIN ELEVATORS
Grain elevators transfer, condition and store grain and other crops
(primarily soybeans) which move from the farm to various processors and ex-
port markets. In general, elevators are classified as either country or
terminal elevators. The U.S. Department of Agriculture distinguishes be-
tween country and terminal elevators on the basis that terminals furnish
official weights, that is, a weight of receipts or shipments which is made
under the supervision of a state inspector. For this study, country and
terminal elevators as defined above will be analyzed separately. In addi-
tion, terminal elevators will be separated into inland and port terminals.
Port terminals are defined as those which are located on major waterways
or seaports and are engaged in the exporting of agriculture products.
Country elevators generally receive grain or soybeans as they are har-
vested in fields within a 10- to 20-mile radius of the elevator. The
country elevators unload, weigh, and store the grain as it is received from
the farmer. In addition, the country elevator may dry or clean the grain
before it is shipped to terminal elevators or processors.
Terminal elevators receive most of their grain from subterminal or
country elevators and ship to processors, other terminals, and exporters.
The primary function of an inland terminal elevator is to store grain in
quantity without deterioration and to bring it to commercial grade so as to
conform to the needs of buyers. As with country elevators, terminals dry,
15
-------
clean and store grain. In addition, they can sort and blend grain to meet
buyer specifications.
The port terminal can provide the same basic functions as an inland
terminal and, in addition, serves as an export point for grain, soybeans and
other agriculture products.
Number and Capacity of Elevators
Data on the exact number of grain elevators are not available; however,
the U.S. Department of Agriculture and Department of Commerce both collect
industry data. Elevators approved for storage of grain under government loans
are listed monthly by The Agricultural Stabilization and Conservation Service
(ASCS) of the U.S. Department of Agriculture. Table 7 contains the ASCS data
for the number and storage capacities of country and terminal elevators.
These numbers represent a large percentage of the number of elevators and al-
most all of the storage capacity. However, not all elevators are registered
under the uniform grain storage agreement, and some companies will register
more than one country elevator with similar freight rates as one unit. The
data show that the number of both country and terminal elevators has decreased
each year since 1969. However, the total storage capacity of country eleva-
tors has increased because the average capacity per country elevator has grown
from 363,000 bushels in 1969 to 422,000 in 1972.
ASCS does not distinguish between inland and port terminals; however,
the annual Economic Research Service (USDA) survey, which uses the ASCS num-
bers as their sample universe, does separate port terminals. The capacities
from the ERS survey are listed below.—'
UNIVERSE CAPACITY
(OOP bu)
1970-71 1971-72
Inland terminals 1,311,552 1,312,439
Port terminals - 352,825 353,825
According to industry sources, of the 477 terminals which were registered in
1972, 64 were port and 413 were inland terminals.
Typical storage capacities at country elevators of recent construction
range from 200,000 to 750,000 bushels; however, many older country eleva-
tors have a capacity of only a few thousand bushels. The average storage
capacity of terminal elevators is 3.8 million bushels; however, capacities
in excess of 50 million bushels have been built at a single location. This
includes bins added onto the original structures, steel tanks, and storage
16
-------
-~»
TH
H
^
W
H
rrf
O
W
<5
Pi
o
H
CO
£5
M
O
S
PH
0
rH
| 1
^
t>
Pi
W
Q
13
^
CO
pq
CO
E3
0
W
fyj
^
^
pn
o
e*
EH
1— 1
U
.
00
CO
n
00
r-l
CO
d
•H
01
H
CU >i
60 -W
CO T-l
t-t y
01 cfl
> D
< Cfl
u
1-^
LO
**o
rt
m
X^v
^3
o
$>•
4-1
•H
u
Cfl
a
CO
u
O u^
O f^
^^^ ^o
n
xj-
^o
oo
«
r-l
£_l
01
o
0
3
oo
o
co
O
4J
cfl
01
I—I
W
rX
J_l
JJ
c
3
0
U
0) >,
60 4J
CO .r4
s-i a
01 cfl
> a
< cfl
CO
vD
m
V
XI
£x
4J
•H
u
cfl
a
Cfl
u
o *^o
O r-l
O 1"^
**^ ft
Cy\
in
oo
n
CN
}_{
CU
XI
H
3
2
CTi
1 —
OO
n
r-^
CT\
VO
O\
, — f
o"
CO
J_l
0)
f
CU
I4J
ex
CU
CO
VO
in
vjD
CN
0
00
^
CO
r-l
r-l
ft
00
v£>
r-l
px.
n
CO
r-l
oo
o
o
00
00
"
1—1
vO
o
m
*^-
00
CO
m
r-.
m
rt
CN
^j-
i— i
n
- 1 — •
CN
r*^
CTs
i— i
O
CO
rJ
CU
f
Ol
4J
a
CU
CO
CO
oo
•
o
CO
1— 1
•
CO
1
CXN
CO
•
r-l
-f-
CN
f^
•
O
1
00
o
CN
1
1O
r-H
*
m
+
t— i
OO
•
r-l
_i_
O
CN
•
CO
1
CN
1^
f*, 1
f~"J ^^
^ vO
tfl CT>
CU r-l
Q)
01 60
60 a
cfl CO
K X!
0) O
t>
17
-------
in warehouse-type buildings--so called "flat storage." The largest capacity
under one roof is 18 million bushels.
The number of establishments and annual sales volume for country and
terminal elevators as reported by the Bureau of Census in the Census of
Easiness are shown in Table 8.-' The data represent those establishments
whose primary source of income was from the direct operation of elevators,
and therefore understates the actual number of country elevators. The
census data show that from 1948 to 1967 there was a significant decrease in
the number of country elevators and an increase in the number of terminals.
Combining the census and ASCS data, it can be seen that the number of
country elevators has continued to decline from 8,549 in 1949 to 7,147 in
1972, and that the number of terminals reached a peak around 1967 and has
steadily decreased since then.
The value of sales from both country and terminal elevators has in-
creased an average of over 2% a year from $6.6 billion in 1948 to $10.0
billion in 1967. However, the value of sales, particularly of terminals,
have fluctuated significantly from year to year.
One additional source of data on the total amount of off-farm storage
capacity is the Crop Reporting Board, Statistical Reporting Service, USDA.
The reported capacity on 1 January 1972, was 5,696,700,000 bushels. This
is 18% greater than that reported by ASCS; however, the figures include
processor storage facilities as well as elevators.
Transportation Mode
The modes of transportation used by country elevators, inland terminals
and port terminals are shown in Table 9. Country elevators receive almost 100%
of their grain by truck and ship about equal amounts by truck and rail. In the
past few years an increasing quantity of grain has been shipped from country
elevators by barge-~7% in 1970-71 and 13% in 1971-72.
Depending on their location and facilities, terminal elevators may re-
ceive and ship grain by rail, truck, barge, or boat. Inland terminals re-
ceive grain primarily by truck and rail, and ship primarily by rail and
water.
A significant trend in transportation is the increasing use of water
by all three types of elevators. In 1971-72 inland terminals shipped 35%
of their grain by water, an increase of 5% from the previous year. The per-
centage of grain received by water at port terminals increased from 25% in
1970-71 to 40% in 1971-72.
An additional trend in transportation has been the increased use of
hopper cars in movement of grain by rail. Hopper cars or "Big John" with
capacities of up to six times the normal boxcar are being used in rapidly
increasing numbers for shipments of both whole grains and grain products.
18
-------
-«,
^
w
pg]
0
w
J
>
Q
<
C/3
^
w
s
C/)
I-l
P9
H
C/3
w
0
8
m
s
i
c/o
eJ
o
E-I
5
1
g.
M
ss
o
•
oo
cu
r-l
CO
H
I — 1
m
•I-l
£
CU
H
CO
CU
CO
M, O
o S
u 3
r-l
CD
CO CO r-l O O>
CM i— i o> O o r^
CO 1^- CN OO vD CO
OO ^O r— 1 CTt 1^ CM
CM ON r— 1 CT> i — 1
OO h- O ON <)• +
CM r-l CM CN
01
w
t
fi
o
CO
cu
C8
^§
0 0
cu v—
1— 1
CO
in^ LO r*1* r*» co
co oo
-------
Table 9. RECEIPT AND LOADOUT OF GRAIN BY TRANSPORTATION MODE
AT GRAIN ELEVATORS2-
9/
Country elevators
1970-71
1971-72
Inland terminals
1970-71
1971-72
Port terminals
1970-71
1971-72
Percent
Received By
Truck
99,8
99.8
40
15
10
Rail
0.2
0.2
55
Water
60
50
25
40
Percent
Loadout By
Truck Rail
48
43
15
17
6
6
45
44
55
48
Water
13
30
35
94
94
Volume of Grain Handled
The volume of grain received and shipped by elevators can change signifi-
cantly from year to year. The table below shows for the three types of eleva-
tors the quantity of grain handled in relation to their storage capacity.
Storage Capacity—'
r
Country elevators
Inland terminals
Port terminals
1970-71
1.8
1.2
7.7
1971-72
2.0
1.4
7.6
The table shows that during the 1970-71 crop year, the average country
elevator received and shipped a quantity of grain equivalent to 2.0 times
its storage capacity. The volume received by country elevators is most
directly affected by the quantity of crops harvested and sold from farms.
Another factor affecting volume is the percentage of grain sold from farms.
20
-------
which is handled by country elevators. There has been a slight trend for
the farmer to bypass the country elevator and ship his grain directly to
processors or to terminal elevators. This trend has resulted from the im-
proved transportation available to the farmer and from the increase in on-
farm storage facilities. However, over 80% of the grain sold from farms
still goes to country elevators.
The volume of grain handled by inland terminals is dependent upon a
number of factors, such as quantity of grain harvested, Commodity Credit
Corporation movements of grain, quantity of exports, and marketing channels
used by grain merchants and processors. In addition, the quantities of
grain handled by a specific terminal elevator are affected by transporta-
tion and location factors. Because of favorable transportation rates,
greater quantities of grain are being shipped from inland terminals by
barge. As a result, terminals which are located on navigable waterways
are handling a relatively greater volume of grain than terminals which have
available only rail and truck transportation.
Also, there has been a trend for the country elevator to bypass the
inland terminal and ship directly to processors or to port terminals. In-
creasing numbers of rice, soybean, and feed processors are buying directly
from country elevators and shipping to their plants. This trend to bypass
the terminal elevator is influenced by increasing vertical integration among
processors and by the location of new plants nearer the production sources
and away from the metropolitan areas.
The turnover rate--?. 7 times storage capacity—for port terminals is
significantly greater than for other elevators because of the large quanti-
ties of grain handled for export. As a result of the large volume of grain
exports during the current crop year, the port terminals will handle an even
greater volume in 1972-73 than in past years.
The actual quantities of grain handled by elevators are not directly
available; however, these quantities can be estimated from a number of
sources. The quantities obtained by extending the ERS survey to cover all
elevators are listed below:
QUANTITY OF GRAIN HANDLED
(000,000 bu)
1970-71 1971-72
Country elevator 5,318 5,912
Inland terminal 1,574 1,837
Port terminal 2,717 2,689
21
-------
The quantities handled at country elevators can also be estimated from
the volume of grain sold from farms and the corresponding percentages which
go to country elevators. By this method, 5,190 million bushels were handled
in 1970-71 and 6,288 million in 1971-72.
Grain Storage
The average volume of grain stored at an elevator during the year as a
percentage of its storage capacity is listed below:
AVERAGE OCCUPANCY—/
(Percent of Storage Capacity)
1970-71 1971-72
Country 52.8 55.5
Inland terminal 55.7 51.7
Port terminal 67.0 67.4
By multiplying these percentages times the total storage capacity for
each type of elevator, the average quantity stored can be estimated as in-
dicated below:
STORAGE VOLUME
1970-71 1971-72
(000,000 bu)
Country 1,560 1,641
Inland terminal 731 679
Port terminal 236 238
Total 2,527 2,558
The volume of grain stored at country elevators is affected by a num-
ber of factors, such as; (1) production and disappearance of grains; (2)
availability of government loans to farmers for storage of grains; (3) amount
of storage capacity available on farms and at terminal and processor elevators-
and (4) amount of stocks held by the Commodity Credit Corporation (CCC). The
most dramatic changes in these factors during the current crop year have been
the increase in exports and the reduction of CCC held stocks. It is difficult
at this time to determine the effect of these changes on the future volume
stored. However, the reduction in CCC stocks will significantly reduce the
amount of CCC storage payments which at the present time is a major source
of income for both country and terminal elevators.
22
-------
Grain Drying and Cleaning
Grain received by elevators can be dried or cleaned before it is stored
or shipped to processors. The percentage of grain received which is dried and
cleaned and the resulting quantities are presented below. The percentages
were obtained from a survey which was conducted as part of this project.
GRAIN DRYING AND CLEANING
Dried Cleaned
Percentage Quantity Percentage Quantity-
of Receipts (000.000 by) of Receipts (000,000 bu)
Country^/ 25.4 1,351 7.8 415
Inland terminal 9.6 151 22.1 348
Port terminal 1.0 27 14.6 397
jj/ The percentages for the country elevators may be too high, because the
sample of country elevators included in the survey was biased toward
the larger country elevators.
Historically, the drying and cleaning of grain was a function of ter-
minal elevators. Country elevators have begun to offer these services and
the quantity of grain dried at country elevators has generally increased
over the past decade. New harvesting machinery, such as self-propelled com-
bines and corn picker-shellers has increased the harvesting rate, and as a
result, some drying is necessary to keep the grain from spoiling. The
volume of grain dried by country elevators can vary greatly from year to
year depending upon weather conditions during harvest.
Location
Elevators are located throughout the United States; however, the major
concentration is in the grain producing states in the Mid-Plains, South
Plains and Great Lakes regions.* The number and capacities of country and
terminal elevators under uniform grain storage agreements by state are listed
in Table 10. Kansas is the largest grain storage state with 13.2% of the
elevators and 15.9% of the total U.S. capacity. Texas has far fewer eleva-
tors than Kansas (494 to 1,001); however, it has 14.0% of the total capacity.
The five states of Kansas, Texas, Illinois, Nebraska, and Iowa together
account for 51.9% of the elevators and 57.7% of the storage capacity.
Mid-Plains: Nebraska, Kansas, Colorado, Wyoming, Iowa and Missouri;
South Plains: Oklahoma, New Mexico, and Texas, plus gulf port facili-
ties; Great Lakes: Wisconsin, Illinois, Indiana, Ohio, Michigan and
Minnesota.
23
-------
332S2::
ON in CM CM •— i c
jasssssasssSssssRgssss
^222225 — — — "-•*<— —
ssssISsssss as-*
s —
-
.eMr^-i—ico^oiAcnocoooT—i
I en •-* CM CM
nj jj g 4-J
,2 o B MI
ffl (0 O tO X C 4«!
co « -rJ 4) 05 y
i-H 0) O
3 45-S
24
-------
Terminal elevators are located in the principal grain-marketing centers,
most of which are in metropolitan areas. However, there has been a trend in
recent years to build terminals in rural areas and there have always been ter-
minals in relatively small cities such as Hutchinson, Kansas, and Enid,
Oklahoma.
Country elevators are almost exclusively located in rural areas. Table
11 lists the number of country elevators in varying sizes of metropolitan
areas as reported by the Bureau of Census in 1967. Of 6,477 country elevators,
5,632 or 87% were located in areas with less than 100,000 inhabitants.
Table 11. COUNTRY ELEVATORS WITHIN METROPOLITAN AREAS - 1967—/
Number Inhabitants
Within Metropolitan
Area
1,000,000
500,000 -
100,000 -
Less than
or More
999,000
499,000
100,000
Sales
Establishments
Number
101
174
570
5,632
Percent
1.6
2.7
8.9
87.0
Value
($000)
77,136
227,107
574,016
4,712,449
Percent
1.4
4.1
10.3
84.3
(nonmetropolitan
areas)
Total 6,477 100.0 5,590,708 100.0
Industry Structure
Country Elevators - The ownership of country elevators can be grouped
into three categories: cooperative, independent, and line. Cooperative
elevators are controlled by farmer associations established under coopera-
tive laws. Independent elevators are owned by individual merchants. Line
elevators are chains of elevators owned by large merchandising or processing
firms. The number and percentage of each type of ownership as reported by
the 1963 Census of Business are presented in Table 12. Of 7,653 country
elevators, 38% were owned by cooperatives, 28% by line organizations, and
347» by independents. The number of cooperative elevators has grown over the
past decade and it is estimated—' that by 1980, 60% of the country eleva-
tors will be owned by cooperatives. The number of line elevators is pro-
jected to increase to 35% by 1980, while the number of independent eleva-
tors will decrease to 5%.
25
-------
Table 12. OWNERSHIP OF COUNTRY ELEVATORS--1963^/'
Establishments
Country - Independent
Country - Line
Country - Cooperative
Total
Number
2,572
2,166
2,915
7,653
Percentage
33.6
28.3
38.1
100.0
Sales
Dollars
(million)
8,059
1,833
1,182
11,074
Volume
Percentage
36.2
23.4
40.4
100.0
The concentration of ownership and sales volume in the country eleva-
tor industry is very low in comparison to other major industries. Table 13
shows that in 1967 there were 4,409 firms which operated 6,477 elevators.
Firms with less than three elevators each accounted for 64.2% of the eleva-
tors and 71.37o of the sales. Firms with six or more elevators accounted for
only 20% of the total sales volume.
Table 13. CONCENTRATION OF OWNERSHIP OF COUNTRY ELEVATOR:
(Single and Multiunit Firms--1967)
,117
Establishments
Firms With
1-2 Establishments
3-5 Establishments
6-25 Establishments
26 Establishments or More
Total
Firms
4,033
234
118
24
4,409
Number
4,160
597
751
969
6,477
Percent
64.2
9.2
11.6
15.0
100.0
Sales
Value
($000)
3,985,180
485,002
525,840
594,686
5,590,708
Percent
71.3
8.7
9.4
10.6
100.0
26
-------
The presence of a large number and different types of firms has meant
that there has been a high level of competition. This competition is re-
flected in the low operating margins which have been characteristic of
country elevators. A summary of the financial condition of 23 regional
grain cooperatives-ii' shows that the rate of return as measured by the
percent of net savings* before taxes to total assets has varied from 0.4
to 3.670 over the 5 years from 1967 to 1971. These data include terminals
as well as country elevators. A survey-t^/ of 51 wholesalers of grain with
sales of less than $1 million shows that for 1971 the profitability (net
profit before taxes/total assets) of individual firms varied from -3.8 to
4.6%. This low rate of return has prevailed despite the fact that many
older country elevators have completely depreciated their major fixed assets.
The existence of vertical integration by integrated processing and
export firms has forced down the profitability of the nonintegrated country
elevator operation, because many of these integrated firms look upon their
country elevator operations as supply sources rather than profit centers.
Terminal Elevators - The ownership patterns for terminal elevators in 1963
with a projection to 1980 are shown in Table 14.
Table 14. OWNERSHIP OF TERMINAL ELEVATORS^
1963 (%) 1980 (%)
Farmer cooperative 20 25
Export integrated merchandisers 25 30
Domestically integrated processors 20 25
Nonintegrated firms 35 20
The percentages represent the operation of terminals rather than actual
ownership, because many of the port terminals are owned by the port author-
ities and leased to grain companies.
As in the case with country elevators, vertical integration in the
terminal operations is becoming more predominate. Many of the largest
grain processors own, lease, or operate terminal and country elevators.
Net profits as defined by private industry are normally referred to as
net savings by cooperatives.
27
-------
Some of the major reasons why these firms integrate back to elevators are
to: (1) have access to specific quantities and qualities of grain, (2)
take advantage of government storage programs; (3) have unique transporta-
tion arrangements; (4) provide a captive market outlet for grain procurement
facilities; and (5) reduce procurement cost of grain.
No data are readily available on the number of firms or concentration
in the operation of terminal elevators. However, the concentration is still
relatively low with over 100 firms operating terminals throughout the U.S.
The competition among terminal firms is high. The presence of strong farmer
cooperatives, grain processing, export, and independent operators, together
with relatively low profit margins is evidence of this competition.
The profitability of terminals has generally been better than that of
country elevators. However, the change in transportation media (from rail
to barge) and the development of large country subterminals has destroyed
the profitability of some terminals which are located in metropolitan areas
without access to water. These terminals have higher operating expenses
than their rural counterparts and do not have the advantage of the lower
transportation rates available from barge traffic. In addition, many of
the subterminals and country elevators are bypassing inland terminal eleva-
tors by shipping grain directly to port or processing facilities.
FORMULA FEED INDUSTRY
Introduction
The formula feed industry consists of mills engaged in manufacturing
prepared feeds for animals and fowl. Feed milling is a grinding and mixing
process in which a variety of whole grains are ground for mixing with high
protein concentrates, food industry by-products, vitamins, drugs, and min-
erals. The resulting feed is usually a formulated blend of ingredients which
provides a nutritional and balanced diet for either livestock, poultry or
pets.
The formula feed industry is the largest manufacturing industry serving
agriculture exclusively, and is one of the top 20 manufacturing industries
in the United States. The industry's sales volume as reported by the Bureau
of Census was $5.2 billion in 1970 and has increased at an annual rate of
4.5% since 1958. The sales volume from 1958 to 1970 of the major types of
feed—poultry feed, livestock feed, and dog and cat food--are shown in
Table 15. The principal increases in sales are from the livestock and pet
food sectors. The increase in livestock feed reflects the increased con-
sumption of meat products by the American consumer and the increasing propor-
tion of beef cattle finished for slaughter by concentrate feeding. The in-
crease in pet food sales from $305 million in 1958 to $1,047 million in 1970
has been caused by an increase in the number of pets as well as an increased
tendency of owners to feed commercial dog and cat foods to their pets.
28
-------
Table 15. VALUE OF FORMULA FEED SHIPMENTS FROM FEED INDUSTRY^
($000,000)
Livestock Dog & Cat
Poultry Feeds Feeds Food Other Total
Year
1970
1969
1967
1963
1958
Percent Change
1969-70
Average Yearly
Change
1958-70
1,518.1
1,478.8
1,560.2
1,445.0
1,474.3
2.7
0.2
2,127.9
1,900.4
1,705.4
1,388.4
958.9
1,046.9
969.7
699.9
441.9
305.4
545.8
485.9
564.2
451.8
337.9
5,238.7
4,834.8
4,529.7
3,677.4
3,076.4
12.0
6.9
8.0
10.8
12.3
4.1
8.4
4.5
The Census of Manufacturers includes only establishments whose largest
source of gross income is from the manufacture of poultry feed, livestock
feed, pet foods, alfalfa meal, feed supplements, and feed concentrates.
Therefore, the Census does not provide full coverage of all feed milling
activity.
A major data source on the formula feed industry is a survey conducted
by the Economic Research Service and the Agriculture Stabilization and Con-
servation Service. This survey collected statistics on all known U.S. mill-
ing establishments in 1969.
17/
Included in the survey were establishments
whose primary source of income was other than formula feed, and also those
which are classified as nonmanufacturing by the Bureau of Census. However,
the survey does not cover the manufacture of alfalfa meal which is included
in the Census of Manufacturers.
A comparison of these two information sources can be made from the total
feed production reported by each. The ERS survey reported total feed produc-
tion in 1969 as 103.9 million tons, while the Bureau of Census in the Annual
Survey of Manufacturers reported 1969 feed production of approximately 52.3
million tons. This means that the Bureau of Census data covers only 50% of
the total formula feed production quantity.
29
-------
Another measure of the Census coverage can be obtained by comparing
the value of shipments as reported by the Census with the value of feed
purchases by farmers as reported by the U.S. Department of Agriculture.
In 1970, farmers purchased $7.18 billion in feed, which compares with $4.19
billion reported by the Census as the value of formula feed shipments ex-
cluding dog and cat food. Based on this comparison, the Census accounted
for approximately 587> of the feed sales.
The ERS survey reported that 7,917 feed manufacturing establishments
produced 1,000 tons or more of formula feed and that their total production
was 101,115,114 tons. Of this, 68,811,750 tons were classified as primary
tonnage and 32,303,364 were classified as secondary tonnage. Primary feed
manufacturing is processing and mixing individual feed ingredients, sometimes
with the addition of a premix at a rate of less than 100 pounds/ton of fin-
ished feed. Examples of specific feed ingredients are feed grains, mill by-
products, oilseed meals, and animal proteins. Secondary feed manufacturing
is processing and mixing one or more ingredient with formula feed supplements.
Supplements are usually used at a rate of 300 pounds or more per ton of fin-
ished feed, depending on protein content of the supplement and percentage of
protein desired in the finished feed.—' The primary tonnage, shown in
Table 16, was further broken down as: 56,800,461 tons (82.5%) complete feed;
11,327,366 tons (16.5%) supplement feed; and 683,923 tons (17.) feed premix.
Materials Used
The feed concentrate balance for the U.S. is shown in Table 17. The
supply utilization and carryover of the major feed ingredients are presented
in this table. Corn, by far the major ingredient, accounts for 587» of the
raw material volume. However, the feed industry's growth is closely tied to
the introduction and utilization of by-products and high protein concentrates.
The utilization of those nonfeed grain ingredients are further detailed in
Table 18. The most important by-product has been soybean meal. Its consump-
tion has more than doubled between 1956 and 1971, and now accounts for approx-
imately 627<> of all high protein feeds. Large numbers of farmer feeders have
shifted from home-produced to commercial feeds. They have insisted on buying
improved-quality mixed feeds made possible by advances in animal nutrition.
Today, most formula feeds contain between 15 and 25 ingredients, microin-
gredients, and drugs. Nutritional research has shown how livestock and
poultry production can be increased per unit of feed by the addition of cer-
tain ingredients such as, vitamins, antibiotics, hormones and drugs.
30
-------
(3
CU
O
a
ro
oo
oo
oo
CM
CM
•
in
o
o
o
H
CO
vQ
CM
CM
t— 4
co
oo
CM
f^
m
oo
CM
O
o
m
t-4
«3>
l-v
CM
0"
^)-
f*^
m
CO
CM
i— 1
00
oo
o
o
1— 1
x a
cu 6 4-1
cu cu
f*4 M O
P4 O
a-,
m
in
CN
CM
r-l
CM
oo
CM
co
CO
CO
in
m
CM
CM
CO
CM
CO
PM
v£)
cu
4J
CU
a
o
o
o
o
CM
CO
00
m
CM
O
in
m
CM
CO
CO
n
m
vO
CO
O
o
00
m
in
CM
oo
!-!
!-i CU
CU 'O
& cu
o cu
i-l H
O P3
I I
cu cu
w >,
M
CO
CO
CO
M
cu
o
M
fQ
H
(-1
•H
CO
Q
CU
CU
CU
W
C
CO
4-1
CU
cu
I-l
-------
Table 17. FEED CONCENTRATE BALANCE, NUMBER OF ANIMAL UNITS, AND FEED
PER UNIT, AVERAGE 1965-69, ANNUAL 1967-72I1/
Year Beginning*"/
Item
Supply
Carryover—beginning of year—'
Production of feed grains:
Corn
Sorghum grain
Oats
Barley
Total production
Imports of feed grains:
Wheat fed
Rye fed
By-product feeds fed
Total supply of all concentrates
Utilization (October-September)
Concentrates fed
-------
Table 18. PROCESSED FEEDS: ESTIMATED USE FOR FEEDll/
AVERAGE 1966-70, ANNUAL 1968-72£/
Year Beginning October
Feed
High-protean
Oilseed meal
Soybean
Cottonseed
Linseed
Peanut
Copra
Total
A^iu.al proteins
Tankage and meat meal
Fish meal and solubles
Commercial dried milk products
Noncommercial milk products
Total
Grain protein feeds
Gluten feed and meal
Brewers' dried grains
Distillers' dried grains
Total
Other
Wheat tnillfeeds
Rice millfeeds
Dried and molasses beet pulp
Alfalfa meal
Fats and oils
Molasses, inedible
Miscellaneous by-product feeds^./
Total
Grand total
1966-70
Average
1968
1969
1970
1971b/
1972£/
(000 tons)
12,029
1,757
214
136
100
14,236
2,040
784
246
378
3,448
1,547
343
424
2,314
4,518
469
1,393
1,588
526
3,294
1,100
12,888
32,886
11,525
2,086
197
135
111
14,054
2,021
835
235
385
3,476
1,550
333
437
2,320
4,469
494
1,523
1,662
531
3,310
1,100
13,089
32,939
13,582
1,794
182
122
83
15,763
2,014
567
230
350
3,161
1,574
361
428
2,363
4,633
490
1,675
1,545
545
3,450
1,100
13,438
34,725
13,467
1,692
258
173
99
15,689
",039
605
260
330
3,234
1,610
361
382
2,353
4,499
436
1,509
1,584
570
3,550
1,100
13,248
34,524
13,178
1,885
263
175
100
15,601
1,891
749
275
300
3,215
1,654
369
404
2,427
4,364
479
1,550
1,568
558
3,550
1,100
13,169
34,412
13,830
2,375
285
200
100
16,790
1,950
500
300
275
3,025
1,700
380
420
2,500
4,300
475
1,575
1,575
r ~7 L
3,600
1,000
13,100
35,415
a_/ Adjusted for stocks, production, foreign trade and nonfeed uses where applicable.
b_/ Pre 1 iminary.
£/ Based on November indications.
d_/ Allowance for hominy feed, oat millfeeds, and screenings,
33
-------
Table 19. FORMULA FEED INDUSTRY (CENSUS OF MANUFACTURERS)—''
1967
1963
1958
Percent Change
1958-67
Companies
1,835
2,150
2,016
-9.0
Establishments
2,355^
2,590
2,379
-1.0
Employees
(000)
53.3
54.6
57.3
-7.0
Value of
Shipments
($000.000)
4,796.9
3,880.1
2,942.0
+63.0
aj Some of the small establishments in this industry have been misclassi-
fied as to industry. This does not significantly affect the statis-
tics other than the number of companies and establishments.
In total, 4.8% of all livestock and poultry production was accounted for by
vertical integration and 31.47,, by production contracts. This concentration
of livestock and poultry production impacts the feed industry by increasing
the direct selling of feed to large feeders, increasing the building of
smaller capacity mills near the customer, and increasing the use of bulk
transport for receiving and delivering feed.
Size of Mills
The production capacity of individual feed mills ranges from 10-12
tons/day to over 1,000 tons/day. The actual production of varying sizes
of feed mills as reported by the 1969 ERS survey is listed in Table 20.
The 5,300 establishments with production of less than 1,000 tons/year
accounted for 407o of the number of establishments but for only 2.67o of the
total production. At the other end of the scale, the 176 establishments
with production of over 100,000 tons/year accounted for 1.3% of the estab-
lishments and 287» of the production.
The total production capacity of feed manufacturing establishments
within various size categories is presented in Table 21. Only the 7,917
establishments with production of greater than 1,000 tons/year are listed.
Within this group the plants with production between 1,000 and 9,999 tons
accounted for 41.870 of the production capacity. The percentage of operating
capacity utilized increased from 36.6% for establishments between 1,000-
9,999 tons to 129.67o for establishments over 100,000 tons/year. These
35
-------
177
Table 20. PRODUCTION OF FEED MANUFACTURING ESTABLISHMENTS—
BY SIZE, 1969-2'
Establishment Size
by Production
in Tons/Year
0 - 999
1,000 - 9,999
10,000 - 24,999
25,000 - 49,999
50,000 - 99,999
100,000 and over
Total
Production
Establishments
Number Percentage
5,309
5,952
1,073
415
301
176
13,226
40.1
45.0
8.1
3.1
2.3
1.3
100
Quantity
(OOP tons)
2,725
21,617
15,546
14,233
20,688
28,900
103,709
Percentage
2.6
20.8
15.0
13.7
20.0
27.9
100
a/ Numbers from reporting establishments were expanded to represent
100% of the industry.
Table 21. CAPACITY OF FEED MANUFACTURING ESTABLISHMENTS!7-/
PRODUCING 1,000 TONS OR MORE OF FEED
Establishment Size
by Production Number of
in Tons/Year Establishments
1,000
10,000
25,000
50,000
- 9,999
- 24,999
- 49,999
- 99,999
100,000 and over
Total
5,952
1,073
415
301
176
7,917
Capacity-/
Tons
59,011
23,256
17,559
18,952
22,296
141,175
Percentages
41.8
16.5
12.4
13.4
15.8
100
Percent of
Capacity Utilized
36.6
66.8
81.1
109.2
129.6
71.6
a/ Estimates of capacity based on full capacity output for 48 weeks of 40 hr each.
Data from reporting establishments expanded to represent 100% of the industry.
36
-------
significant differences in utilized capacity can be accounted for by the
operational economics of the different size plants. Large plants are more
automated and require much larger investment in buildings and equipment.
To be economically competitive these plants must effectively utilize their
equipment by operating multiple shifts. On the other hand, the small feed
mill has less capital investment, less transportation costs, and often
serves a captive market; therefore, it does not have to operate at capacity
to be economically viable.
Less than 75% of the total feed manufacturing capacity-based on opera-
tions of 40 hr/week for 48 weeks—was utilized in 1969. If required, most
feed mills could operate on a two shift basis which would mean that current
production is at only 36% of total capacity.
Plant Location
The number and production volume of feed manufacturing establishments
producing 1,000 tons or more of formula feed is listed by state in Table 22.
The highest concentration of mills is near the feed grain and livestock and
poultry producing areas; however, there are feed mills in almost every state.
Iowa has the greatest number of establishments with 9.2% of the nation's
total, while Texas has the greatest production volume with 9.0% of the total.
Changes in the location of major livestock and poultry production areas
to the south and west of the Corn Belt have forced the formula feed industry
to move also. This geographic movement toward major feed-consuming areas
contributed to the decentralization of the feed industry. This trend from
distant large-scale mills with extensive distribution organizations to local,
demand oriented feed mills supplying local production units has been quite
significant.
Characteristics of Feed Manufacturing Firms
In general, the number of companies in the feed industry has decreased
over the last decade primarily as a result of the trend toward vertical inte-
gration. Estimates of individual manufacturer's tonnage indicate that the
top 10 feed manufacturers in 1972 were:
1. Ralston Purina Company 6. ConAgra
2. Allied Mills 7. Farmland Industries
3. Central Soya 8. Federal
4. Cargill-Nutrena " 9. Carnation-Albers
5. Agway 10. Gold Kist
37
-------
Table 22. LOCATION OF FORMULA FEED PLANTS^'
17/
State and Region
Maine
New Hampshire
Vermont
Massachusetts
Connecticut
New York
New Jersey
Pennsylvania
Delaware
Maryland
Establishments
Number Percent
13
6
12
14
5
259
25
288
20
65
Production
Tons
502,668
165,162
794,900
233,574
257,264
2,936,160
375,877
2,739,110
690,786
1,361,881
Percentage
NORTHEAST
Michigan
Wisconsin
Minnesota
LAKE STATES
Ohio
Indiana
Illinois
Iowa
Missouri
CORN BELT
North Dakota
South Dakota
Nebraska
Kansas
NORTHERN PLAINS
Virginia
West Virginia
North Carolina
Kentucky
Tennessee
707
237
510
402
1,149
459
493
475
730
302
2,459
80
159
343
396
978
115
19
233
128
113
8.9
14.5
31.1
12.4
10,057,382
1,594,085
4,506,266
3,509,848
9,610,199
3,331,439
4,067,681
4,464,906
6,716,940
3,365,509
21,946,475
412,257
1,315,948
3,584,675
4,281,534
9,594,414
1,166,797
85,592
3,238,965
915,811
2,549,350
10.1
9.5
21.7
9.5
38
-------
Table 22. (Concluded)
State and Region
APPALACHIAN
South Carolina
Georgia
Florida
Alabama
SOUTHEAST
Mississippi
Arkansas
Louisiana
DELTA STATES
Oklahoma
Texas
SOUTHERN PLAINS
Montana
Idaho
Wyoming
Colorado
New Mexico
Arizona
Utah
Nevada
MOUNTAIN
Washington
Oregon
California
PACIFIC
47 States
Establishments
Number Percent
608 7.7
61
197
97
114
469 5.9
98
93
48
239 3.0
145
438
583 7.4
73
98
19
98
51
32
44
8
423 5.3
56
55
191
302 3.8
7,917
Production
Tons
7,956,515
542,497
4,289,601
1,515,814
2,853,182
9,201,094
1,973,666
3,342,408
804,335
6,120,409
1,770,112
9,048,082
10,818,194
583,486
1,065,368
171,522
2,442,233
925,830
1,275,052
413,138
120,740
6,977,369
1,000,640
765,166
6,966,297
8,732,103
101,014,154
Percentage
7.9
9.1
6.1
10.7
6.9
8.6
39
-------
These 10 companies manufactured 27-28% of the U.S. tonnage of formula
feed. All of them are highly diversified; as illustrated by the fact that
each has major activities in at least four 4-digit SIC industry classifica-
tions.
In comparison with other major manufacturing industries, the formula
feed industry is highly decentralized. The concentration ratios as re-
ported by the Bureau of Census are shown in Table 23. In 1970 the four and
eight largest companies had 247o and 34%, respectively, of the value of in-
dustry shipments which are almost the identical percentages as in 1935.
The trend in the industry toward diversification and vertical integra-
tion is illustrated by the increase over the last 10 years in the number and
size of feed mill establishments which belong to multiplant firms and the de-
crease in those which are single plant firms. These numbers are shown in
Table 24. Feed manufacturing is losing its identity as a separate operation,
and is becoming more a part of the total food producing complex.
According to the ERS survey, 46% of the formula feed mills belong to
corporations and these mills account for 65% of the total production by feed
manufacturers. There are a number of larger farmer cooperatives in the feed
industry, and they account for approximately 23% of the establishments and
20.5% of the production. A summary of the ownership pattern of feed mills
in 1969 is shown in Table 25.
ALFALFA DEHYDRATING INDUSTRY
Introduction
The dehydration of alfalfa started in this country early in the 20th
Century but did not begin to be of commercial importance until the 1930's.
During the 1940's, the industry expanded rapidly, and reached a stage of
relative maturity in the late 1950's. Alfalfa dehydrators are located
throughout the country except in New England and the southeastern states.
The center of the industry is in the Northern Plains. Figure 4 illustrates
the general distribution of plants in the continental United States as of
1972.
Raw Materials and Products
Alfalfa is the only raw material processed in alfalfa dehydrating
plants. Standing alfalfa is mowed and chopped in the field and transferred
to a truck which transports the chops to the dehydrating plant. Chapter 3
discusses the operation of the plant.
40
-------
*>l
li
CO
W
U
£5
<
iJ
S-i
K^
pq
oi
a ><
fo oi
.CCOUNTED
;ED INDUST
<; w
^4
CO
H W
1 *
S a
M M
ffi
CO CO
M
PK M
O J3
H £j
W O
U 0
Pd
w
P-I
•
CO
CM
0)
i— <
JD
CO
H
CO
4J
C
CU
o<
•H
CO
r»
!-l
4-1
CO
•§
,5
4-1
O
CU
3
CO
>
>,
PQ
r4
O
p*-l
T)
to
rJ
4J
CO
0)
«* ff
CO
rJ
i—i
tfl
4-1
O
H
co
CD
•H
c
CO
o
CJ
CO
CJ
•H
C
to
&
6
0
o
CO
cu
•H
d
CO
Q.
1
o
o
S~*^ S~\ X~N y^N X"N
^£ oo ^fi *cj* ^o *^c ^^ ^^
JSLOjSlA^j-S^nlS
\^X NW' \»^ ^— ^ ^— ^
"^ ^
CO ON H
/-\ in ^N o VD r^- CM /->
<2coM3inm
-------
Table 24. TYPE OF OPERATION IN FEED INDUSTRY—
Establishments
Multi-Unit
1967
1963
1958
Single Unit
1967
1963
1958
Numb er
795
754
652
1,560
1,836
1,727
Percentage
33.8
29.1
27.4
66.2
70.9
72.6
Value
($000,000)
934.4
671.0
551.9
292.4
312.7
247.0
AddedS-/
Percentage
76.2
68.1
75.0
23.8
31.8
25.0
a/ Value added by manufacture.
Table 25. OWNERSHIP OF FEED ESTABLISHMENTS
PRODUCTION OF OVER 1,000 TONS
Establishments!/
Corporations
Partnership
Single Owner
Farmer Cooperative
Other
Total
Number
3,617
760
1,672
1,844
24
7,917
Percentage
45.7
9.6
21.1
23.3
0.3
100.0
Production
(000 tons)
65,343
5,949
8,808
20,702
205
101,014
Percentage
64.7
5.9
8.7
20.5
0.2
100.0
a/ Numbers from reporting establishments were expanded to represent 100%
of the industry.
42
-------
CN
r^
ON
to
(50
a
•H
4J
Cfl
J-l
JS
0)
•U
CB
u-i
d
o
•1-1
4-1
&
•H
co
•1-1
CO
O
•i-l
Si
CX
CO
)-i
60
O
-------
Dehydrated alfalfa is important for its protein quality, unidentified
growth and reproductive factors, pigmenting xanthophylls, and vitamin contri-
butions, although its carotene content is not as important as it has been in
past years.
Trends in the production and utlization of alfalfa meal in the United
States are shown in Tables 26 and 27. Industry growth, in terms of volume
of production and utilization, has been relatively continuous. Since 1948,
annual production gains have occurred 15 times; decreases from the preced-
ing year have occurred four times. The gains resulted mostly from adding to
industry capacity. Setbacks were mainly caused by adverse weather conditions.
The Northern Plains states account for over 50% of the total U.S. output
of dehydrated alfalfa. Table 28 presents data on production in the Northern
Plains states for the early and middle 1960"s. Nebraska alone accounted for
35-45%.
Table 29 presents information on the value of shipments from alfalfa
dehydrating plants in 1963 and 1967. There is some discrepancy between the
production figures quoted in Table 29 and those given in Tables 26 and 27.
The reason for this discrepancy appears to be that Table 26 covers the
seasonal year from May 1 to April 30, whereas Table 27 shows a year as
being October through September, and Table 29 reflects the calendar year.
Industry Structure
About 200 firms now operate dehydrating plants--an average of nearly
one and one-half each. A limited number of firms each operate more than 20
plants at various locations. The majority, however, have only one plant.
Industry production is concentrated among firms. Twenty percent pro-
duce more than 70% of annual tonnage. Approximately 54% of the firms con-
tribute only 12% of the industry production. Firms producing less than
1,000 tons annually represent about 12% of the total number of firms but
only 17» of the total production volume.
About three-fourths of the alfalfa dehydrating plants in operation are
investor-oriented corporations. The remaining fourth are partnerships, in-
dividually owned firms, and cooperatives. Investor-oriented corporations in
the alfalfa dehydrating industry consist of owner-operated plants and those
that have hired managers. The owner-operated concerns are generally family
enterprises or partners who choose to incorporate. They differ little
from individual ownerships and partnerships in operations.
44
-------
Table 26. DEHYDRATED ALFALFA PRODUCTION AND UTILIZATION!!/
1948-49 TO 1971-72 SEASONS
Production
Season
May 1- April 30
1948-49
1949-50
1950-51
1951-52
1952-53
1953-54
1954-55
1955-56
1956-57
1957-58
1958-59
1959-60
1960-61
1961-62
1962-63
1963-64
1964-65
1965-66
1966-67
1967-68
1968-69
1969-70
1970-71
1971-72
(000 tons)
732.0
800 . 3
907.5
846.5
1,020.1
855.6
1,063.7
1,163.7
962.3
1,110.7
1,122.9
1,171.6
1,242.0
1,277.9
1,317.8
1,437.5
1,575.0
1,596.7
1,660.2
1,622.0
1,586.5
1,737.2
1,698.1
1,634.0
Percentage
Change From
Previous
Year
9.3
13.4
-6.7
20.5
-16.1
24.3
9.4
-17.3
15.4
1.1
4.3
6.0
2.9
3.1
9.1
9.6
1.4
4.0
-2.3
-2.2
9.5
-2.3
-3.8
Utilization
(000 tons)
709.1
820.3
906.6
851.6
968.8
899.6
1,002.7
1,135.9
1,036.1
1,064.5
1,167.0
1,143.2
1,122.3
1,265.3
1,293.8
1,409.1
1,565.3
1,658.5
1,650.4
1,514.2
1,660.8
1,755.4
1,742.1
1,613.3
Percentage
Change From
Previous
Year
15.7
10.5
-6.1
13.8
-7.1
11.5
13.3
-8.8
2.7
9.6
-2.0
7.0
3.4
2.3
8.9
11.1
6.0
-0.5
-8.3
9.7
5.7
-0.8
-7.4
45
-------
CO CM GO ^
o --1 o 01
in ^-i ,-i ^-t
V4 C Ji 4^
ra C o M
w en
3 n
T3 O
0 CX
0. t3
-------
1
o
M
H
O
O
o
PS
PH
d
Ew
g
fn
1 T
tH ^
< C
o
CO 4J
H O
< 0
J 0
py;
pi
K
H
O
63
.
oo
cu
1— I
43
a
H
r-4
>•
cc
af
G
•H
C
C
•H
bi
QJ
FQ
CO
cc
OJ
!
njl 0"! CN O <— i
t—i v£> i— i T— i CT\ \D
CN >wD a\ r^ o
vD i — 1 O^ vD f^» CT^
ty\ O cTi i 00 ) CO O
i— i \o i— < V| -\x— "*~" co r^-
CNI 10 o r^. co
CO O LO LO i— ) -fc -JC CN U~l
O"\ O CT\ CO CN in ^O
i— i m i— i r-s m
^ f~l i — 1 CN CO \&
1 1 0000 * *
vo coo- ^ ^O CO CN r^* CT^
\n oo co ^o oo CN
0 ° • • o -
^ r- co co i— ' -J< -J< ^o in
O^ ^O -«^" CM CN \& r^.
i — i <± i— i vD in
CO
C co
£ ^ *H a)
O A! O CO 4-> « ,£J ^C
co co CD O C -u -u
cu coco <1)X3A!O I-< O
4-» MracoC-Pcoo o
co ^iC3Ci-iPcn 2; i— i
4-1 CU CO O -r-l O -H t-H
C/3 ^ylM^IS 12 ,
m r-<
• I— 1
f^. CO
CO ^5
-J" ""O
r-l >
•a
c
•iH
C
CO
OO 43
o 4J
r^^
t-H \->
CO OJ
f-T 5
CO
^
CO
OJ
ccf
ON
C
l-» co
p^
CN CO
CO
T— <
CO
CD
AJ
CO
4J
n co
CO
O OJ CU
o 4J CO
CN CO CD
-------
Table 29. QUANTITY AND VALUE OF PRODUCTS
ALFALFA DEHYDRATING PLANTS
Year
1963
1967
Quantity
(000) short tons
1,726
1,739
Value
($000.000)
71.2
74.6
Those that have hired managers include the industry's large firms.
These differ among themselves in that: (1) several have many owners while
others have a few; (2) some are organized solely or mainly to dehydrate
alfalfa, but others are part of a larger organization whose principal
business is not dehydrating; and (3) two or three are multiplant firms, while
others operate rather large-scale operations at one site.
Individual ownerships and partnerships among dehydrating organizations
are usually small. They include plants operated for many years by original
owners. The presence and persistence of these types of organizations demon-
strate how easy it has been to enter the industry, even with limited capital,
and the ability of small plants to compete.
Cooperatives have several operations of substantial size and a few rela-
tively small ones. Two general types of cooperatives are: (1) those organ-
ized by growers as marketing outlets for their alfalfa; and (2) those added
to feed mixing cooperatives—the larger group.
Characteristics of Plants
Before 1950, additional new plants were the reason for increased annual
production in the industry. After 1950, the industry's annual production con-
tinued to increase, but with fewer plants. Construction of larger plants and
existing plants operating at high capacity caused the larger output.
Increased plant capacity came about in several ways. Some plants added
a drier or complementary equipment to existing facilities. Sometimes the
addition was purchased new, but frequently it was obtained from a plant that
had closed.
With the development of larger drying units to supplement or replace
smaller ones, a number of new plants, including a cooperative, began opera-
tions with these high capacity units.
48
-------
The improved production-capacity ratio in the dehydrating industry
can be attributed to the experience operators have gained. Thus, they can
use the facilities to better advantage. In addition, there has been a shift
in the geographical concentration of operations to areas better suited to
growing alfalfa for dehydrating.
Several plants produce more than 35,000 tons of dehydrated alfalfa
annually. About two dozen, however, produce less than 1,000 tons a year.
Average annual production for each plant during the 1966-67 season was
5,500 tons.
GRAIN MILLING
Introduction
The grain milling industry includes establishments engaged in milling
flour or meal from grain. The Census of Manufacturers classifies wheat flour,
durum, dry corn, rye, and oat milling in the standard industrial classifica-
tion (SIC) 2041. Rice milling and corn wet milling are not included.
Grain milling has been transformed from a semi-agricultural and some-
what seasonal occupation into a complex industry. Current features of the
grain milling industry are highlighted in the following sections.
Raw Materials and Products
Grain mills process grains into a spectrum of flour and meal products.
Table 30 illustrates some of the main products from various grain milling
operations while Table 31 presents data on the quantity and value of ship-
ments in 1963 and 1967.— Individual milling operations and their associ-
ated raw material product flow patterns are discussed in the next sections.
Wheat Milling - Flour mills draw wheat from wide regions, often from a
quarter of the nation, and the destination of their products is even wider
in scope. Table 32 presents a summary of commercial wheat milling produc-
tion from 1965-71, while Table 33 illustrates commercial wheat milling
production by geographic areas for the years 1970 and 1971. These data
indicate that flour milling has become either a stable or declining industry.
49
-------
Table 30. PRODUCTS OF GRAIN MILLING PLANTS
Milling Operation
Wheat
Durum
Corn
Oat
Rye
Products
Bran, Shorts, Clear Flour, Germ,
Patent Flour, Millfeed
Semolina, Clear Flour, Millfeed
Germ, Cereal Grits, Brewers Grits,
Corn Meal, Corn Cones, Corn Flour,
Brewers Flakes, Corebinder, Hominy
Feed
Flour, Quick Flakes, Regular Flakes
Flour, Meal, Millfeed
50
-------
3 S
cp
5
o
o o
o o
o o
Ro)
«
i-H 4J (0
fc M i-H
O r-4
4-1 &. O
a x a
01 flj
J
2 2 75
3 H C
d) Ji AJ
^ i-H (3
Q) 3 O
M n u
•O « •* T4
X 10 -O t3
4J CU
0-8
4J a>
CO Jrf
ip
ip
a a
*4 i-l
CO
60
a
•H
•H
rt
M-l
t-»
4-t
LikJ-i-lJ-'i-iWLiW
SJ3 £ O O O
£ co tn EH i*
§s
51
-------
"(J | ,-1
oo oo o m
1,-
-. ol ol
X
<«
o
•U
S
OJ
0
CM*
OO
o
00
rH
4-1
fj
CO
tO
CO
o
o
0
rH
4-1
to
til
rH
>T
CM
en
O"!
o"
00
"°.
4J
tj
CO
to
CO
o
o
o
i-H
CO
•f-f
QJ
CO
d
RI
3
O
tt-
fi
3
n
OO
00
m
xTl^J
o
en
4J 4-t
J2 S
n n
CO CO
o o
0 0
o o
1
Including Farina 1
o
4-1
3
00 01
CQ O
O
en
oo
rH
en
o
rH
oo"
4J
J2
(0
CO
o
o
o
rH
en
d'
CO
£
•iH
x
|
4-1
a
CU
u
X
g
rH
CO
rH f
X c
s_/ (
en en
CM CM
5 5
CO CO
d d
o o
£ t!
CO CO
0 0
0 0
o o
rH r-H
IH
3
O
h-
d
to
t-|
(U
4-1
O
CO
4-1
3 OJ
TJ a
O En
M
rH
rH £
ra
4-1 0)
to x;
QJ S
1?
T\
r.
M
o
3-
o
-*
en
d
0
4-1
CO
0
o
o
rH
S
CO
01
en
X
X
CO
O
Produ
rH
X
g
O
c
o
iH
4-1
1
CO
d
o
o
d
3
o
4H
oducts
PH
g
O
0
CM
CM
S
m
in
?
u
CO
CO
CO
o
o
0
CO
Oj
E
0
u
%
en OO
en *H/
CM O
u~) 00
r- CM
00 -H/
4-1 4-1
i s
CO CQ
(0 CO
CO CO
O 0
O O
0 0
O
CO
CO
l-l
j
pa
t_i
4-1
a
u
X
Ed
d
s
rH O
« 02
N
IH CO
O
O CO
4-1
•d -rl
CU rl
S O
o) d
d
CO rH
•0 i
CU *rl
01 d
>1 rl
E ^— '
O
S3
"u|
CM
°.
4-t
3
CO
to
CO
o
o
o
o
4-1
l-l
D
O
d
8
CJ
CO
4-1
U
t-l
p-i
d
n
n
r
0
in
rH
0
v^
"Z7
g
efl
CO
CO
O
g
CO
eft
4J
o
3
TJ
2
a-
£
g
O
o
X
•oi
x
u
01
d*
CO
4J
Pro due
•rl
d
i-i
X!
4-1
0
00
o
CM"
o
CM
4J
3
o
en
n
o
o
o
t-l
-1
o
CD
en
4J
s
CJ
CO
CO
CO
o
o
o
'cu*
d
rl
O
o
4-1
CO
a)
0) TJ 01
x d >,
O co O
e 3 E
U O Ed
El4
ual companies .
sacks values at
20411.
.gures for indivic
For 1963, 292,000
fted from 20455 tc
idual companies.
disclosing f
in 20411.
our were shi
es for indiv
•a 3 4-1 3
•rl O 60
O t-« 00 i-l
CO -.-1
60 co 60
(D) Withheld t
and self-ris
lion of self-i
avoid disclos
Q) -rH O
O «
-O a • c?\
CO en oo
co a- 4-1 O
nts zero. (X) Not applicable. (NA) Not
>0411 and 20455 were revised to include al
>sphated flour and 1,650,000 sacks valued
i 20411 61 are included with product code
oi co a. o
v< a) u
CL tn «4H
4) to O 4J
•n o
0) 3 -H
4-1 TJ E M
o o o
M a) 4-j
co x: to
TJ H a
d
CO
4J •--,
CO B)| Xi
CT\
4J
C
r<
CU
to
QJ
CP
4-1
O
c
CO
QJ >
SU
cO
CM CO
TJ O
d o
to o
en r-
O 4-1
§ °
co d
TJ
TJ Q)
d tu
3
O
OJ
tH C
XI O
|H r-l
M-l .H
E
QJ in
CO 00
-U
TJ CO
c
QJ
co 3
4-1 rH
•rl CO
M >
60
CO
d c
rl O
O 4-J
CJ
• 4J
0 XI
C 3 w
O TJ
•rl O O
E 5*. CM
. GO
00 d W
•CO- rH TJ
4J -H i-H
CO E O
d
^1
52
-------
\
CM|
r-<
O
H
m
rr\
, — i
1 t
t-y'
o
H
H
0
s
o
S|
o
M
rJ
B
1
3
O
r£l
S
g
s
£
i
p^
oo
4
CM
CO
cu
,-f
,0
cfl
H
C
O
to 4-1
3 0
O cfl
fa 4J
X
w
n
rJ
(1)
M)
CO
J_)
01
t*
vo m in co »— i oo cj^ cr\
^-J- r-l CM i— ( in O t*»
vO ^D r-i
CO O CM r-l O O OO
•N »t *\ »» *l ft *»
CD co in *^~ ^j" co o*\
in in -J" in m m <)•
CM CM CM CM CM CM CM
^1
CO
cu
m \o r-~ oo ON o r-i
^o vo *>o vo ^0 r*^ r***
i— 1 r-l r-l i— I i— * r-l i— (
53
-------
4J 4-J CO 4-1
a -M
to &
- u 5
<)• ^1 ^H
X CO CM O
CO ^ ^j- CM
3
O
O O
3
__
^ m
~ o t^ m <» m o
•1 N 00 rf (^ vc 0
J
ON VJ
D O~
D
! S QJ
O
C
a)
u
01
PH
>i
•r-l
s
13
a)
•H
CO
w
*-t
s
"^^
CO
o
H
-
d
•<
4-1
•H
CO
CO
U
O
O
^
"^-^
>
O
CO
CD
O
•-^
ral
wi
u
CO
en
4-»
a
w
u
CO
CO
4-J
s
o
ON i-lr-4 OCOOOCO
CO Ol — CM^-CMp^CM
r-~
CM i— I
T—l OO
CMCNOOCOvDi-l
ON r- en co
.s
p
CO 4-1 .C
4-) C CO
§ I S
I
•H T3 m -r-l
-O QJ in rH
4-1 CM O
t3 )-j .C
o
CL t-i J3
a) co u
)-( eg p
>, en
w
co a) en
x: co
>-, 4-1 QJ
4-> r-(
•H Ml C
O d 3
co -H
G, ^ en
54
-------
Durum Milling - Durum wheat has been grown in the United States since 1900
but it has never accounted for more than 10% of the total wheat acreage.—
Over four-fifths of the durum crop in the United States has been produced
in North Dakota over the past 8-year period (Table 34) with lesser quanti-
ties being produced in South Dakota, Minnesota, Montana, and California.
Table 35 presents data on durum wheat products for the years 1970 and 1971.
Rye Milling - Rye grain can be grown in any area where wheat is grown. The
average yearly production for rye in the U.S. is about 30 x 106 bu. The main
producing area is the Great Plains as shown by the data in Table 36.
Table 37 summarizes commercial rye milling production for the years 1970
and 1971.
Dry Corn Milling - Both white and yellow corn are milled. The products pro-
duced are essentially the same and there is usually little difference chemi-
cally or in taste. The high-crop yielding yellow corn hybrids have resulted
in yellow corn being usually the lower priced raw material, and this has
dictated that millers turn to yellow corn as progress was made in corn breed-
ing. Today only a limited quantity of white corn is grown and the millers
that need it for special customers that still desire the white, rice-like,
grits probably pay a premium.
Table 38 summarizes data on the supply and use of corn in dry milling
operations during the 1964-71 period.
Oat Milling - The processing of oats for hot cereals and industrial uses
accounts for only a small portion of the total bushels harvested each year.
About 90% of the crop remains on the farm and is fed to poultry and other
farm animals. Table 39 summarizes data on the supply and use of oats in
on /
processing operations for the 1964-71 period.•=—
Industry Structure
As noted in the Introduction of this section, the U.S. Department of
Commerce combines wheat flour, durum, dry corn, rye, and oats milling in
the (SIC) Code 2041. As a result, it is not possible to break out some of
the data reported in the Census of Manufacturers and discuss individual seg-
ments of the grain milling industry. Other information sources provide
more details on each segment. Information on the milling industry as a whole
is summarized in this section, and each segment will be discussed in more de-
tail in subsequent sections.
55
-------
^»
•ol
Nl
ON
vO
1
r-l
VO
ON
I-I
*
CO
ta
H
H
CO
^
M
a
o
M
B
* — i
o
o
BJ --N
P-i 3
rQ
3 o
(*! O
S3 O
Q v-/
CO
H
H
H
CO
O
CiP
H
r-1
g
,
^-i-
CO
CD
I-I
rO
cS
E-i
p
10
CO
r— 1
vO
ON
I—I
vO
I—I
VD
CM
VO
ON
r-l
CO
00
vO
r-H
CO
vO
ON
r-4
O
m
-*
„
r-l
^j-
vO
ON
r-H
VO
in
r-i
CM
m
VO
ON
I— 1
CO
oo
oo
CM
VD
VD
rH
CM
i— 1
in
n
i— i
r^.
VD
ON
r-l
m
o
CM
•*
CM
OO
VO
ON
I—I
oo
CM
r-l
m
CO
ON
VD
I i— 1
CM
m
in
M
CM
to
4-J
O
CO
CO
4-J
n
CO
CO
a
c
•r-l
S3
0
CO
v^
^^
CO
»
CM
\^f
CO
•
CM
v^_^
^^
CO
,
CO
N^_
^
r-f
,
^
;J
,
CM
*^/
^_^
CO
CO
N, 1
_^
CM
CO
^_s
•^v.
rol
s— *.
•
CM
V /
O CO
0 •
oo ON
" iv
vO v-^
r— 1
^•^
CM O
co •
m co
" oo
ON v— '
in
CM 5
m
iv m
« oo
CO ^
^
^^
in oo
oo •
ON VD
« co
VD •• — '
m
^
r-l ON
i— 1 .
•• OO
r-l *-^
VO
O r-l
CM .
rH IV
- 00
m x--
m
^^
oo vo
oo .
00 CM
« 00
in
^-
o -^t"
CM .
^'
r-l
^*^
O 1^
VO •
Q1^ Q^
ft \^S
vO
/— \
CO LO
•"3" •
co r^.
^ *. ,
CO
^^
CM rv
i-H
m vo
n ^_^
^
IH
to
3
O
•H
4J
r-l
O.
«
r-l
O
<4H
C
O
•iH
4-1
O
3
T3
O
M
(X
, — i
tO
o
4-1
CO
r*,
4-1
l*H
0
CO
Ml
to
4-J
(U
O
i-l
01
a.
to
-
CO
4-J
ra
4-1
CO
CO
r?
4-J
4-J
a
co
CO
CO
J_|
a.
co
^
CO
CO
CO
CO
XI
4-1
C
CO
IH
to
P.
C
•iH
CO
CO
3
TO
^
0)
^3
t-i
•^v^
tOj
-------
Table 35. DURUM WHEAT PRODUCTS: 1971 AND 1970-2!/
1971 1970
Jan. 1- July 1- Jan. 1- July 1-
Item June 30 Dec. 31 June 30 Dec. 31
Durum wheat ground (thousand bushels) 15,821 16,415 16,178 15,876
Straight semonlina and durum flour
produced (thousand sacks (cwt.)) 7,347 7,904 7,501 7,312
Blended semolina and durum flour
produced (thousand sacks (cwt.)) (D)£/ (D) (D) (D)
a/ Withheld to avoid disclosing figures for individual companies.
Table 36. YEARLY AVERAGE BUSHEL PRODUCTION OF RYE BY STATES^-'
Minnesota 2,142,000 bu
North Dakota 5,355,000 bu
South Dakota 7,666,000 bu
Montana 471,000 bu
Kansas 1,121,000 bu
Nebraska 2,730,000 bu
Total of six states 19,485,000 bu
57
-------
1
2
rj
1~*
^
r— \
'
S
W
ffl
y
i
o
H
U
PRODU
CELLING
1^1
w
J
^
1— 1
u
pj
w
Q
o
o
cn
0)
• '
cfl
H
C
O
•H
3 0
O co
i — I ^
Pn w
w
}_,
0)
PM
CO
•a
3
o
PL)
(I)
M
CO
<1>
•a
01
0)
1-1
1-1
•H
S
c
3
O
0
a)
c^1
C
^ o
3 -i-l
O 4-1
t-H O
PM 3
T3
Hi O
PC) py
0)
U
CO
Pi
}_,
3
O
i— I
pt.
M-l
0
O
TO
00
4-1
&
u
c
O
•H
4J
U
3
O
P-t
^
3
O
r-H
^1
0
<4-f
O
o
o
>-l
^^
B-S
T3
a)
0)
fo
,— 4
! 1
•H
o **o
• •
o oo
oo r^
r- o
* •
m vo
CM CM
^
cy> cn
0)1
(3 CM CM
| r-4 --I
/— *
CO
e
o
4J
i-H 0
vo m
cn cn
O r-l
cn cn
^— s
3
O
0
o
I-H r~-
00 vO
CM -d"
m m
^
w
0
CO
CO
•U
CJ
eO
a)
vO O
cn -d-
A f\
CM CM
i-l O
r^*- r*»
c^ 0*^
1-1 i— i
58
-------
I—I
1
vD
r-l
W
H
2
CO
p
W
H
CO
S5
CO O
CJ
60
C
•rl
rl C
CO C
rl
O
CO
•0
o
o
P*J
r-l
&
CL
CO
cOl
CO
S-l
0
i
h-l
C
O
%P4
4-J
CJ
3
•O
O
M
PM
,_,
^
4-J
U
O
S-l
CU
0
4J
CJ
o
00 O CO sj" CO i — 1 -sj*
CN en co ro co co CN
o rH p*» r^- -^j" ^o c^
r-l r-l r-l r-l r-l r-l r-l
O> O r-l r-l CN CM CN
r-l CN CN CN CN CN CN
CN ro m co m ON oo
ocNcyiinmvOricNi
mm<}-u->ininin^>
r-lr-lr-lr-lr-li— lsC|-i— 1
<)- "vT
CO *^ -J" ^^ "vf" *d" *vh "^
r^ r^ f-^ co CNI ff} c^ co
CO *sf *sf CM VO r-l O** **Q
lT|r-IOOC»r-lr-((TlVO
n «\ ft *t
r-l r-l r-l r-l
^ ^
O | O j
*J~ LO ^O r*->- 00 ON O T-H
^^ vo vo vo vo ^D r^"* r*^*
O^ ON ON ON ON ON ON ON
i-H i-H i— \ rH'i-H r-l i-4 i— 1
C! 4J
3
CO
C
cu
O
'•H
0
3
CO
cu
^4
3
PQ
cu
&
4-1
1+-I
O
CO
4-J
rl
O
0,
cu
^1
E
O
U-l
'O
CU
r-l
•rl
&,
O
CJ
CO
4-J
O
3
•XJ
O
^i
cu
C
rJ
O
CJ
m
o
4-J
C
CU
r-l
CO
•rl
3
cr
CU
C!
•rl
CO
S-i
60
'O
C
CO
C
•rl
CO
o
g
0
ft
rl
3
0
r-l
14-1
t\
x— ^
CU
CO
3
TJ
r-l
O
.£
CU
CO
3
0
-fl
6
CO
M-l
60
C!
•rl
'O
3
CJ
G
•rl
^
r-l
CO
^
CJ
M
O
O
60
C
•H
CJ
3
•a
0
rl
cu
C
•rl
'rj
CU
CO
3
CO
CU
•rl
4J
•rl
4-J
C!
CO
3
cr
-0
cu
4-1
•rl
4-1
CO
-^
(4-4
O
CO
4J
rl
O
Cu
CU
rl
C
o
'O
CU
CO
CO
PQ
•
CO
S-i
0
3
cr
•rl
r-l
4J
r-l
Crt
g
^rj
0)
4-1
C
CU
6
cu
*4-4
T3
CO
13
o
O
H-l
rl
O
M-l
CU
CO
3
CO
CU
^*
r-l
CJ
CJ
•rl
• f.
ca
CU
v^
CO
r-l
^4-1
•a
rj
CO
CO
4-J
•rl
!-l
60
•
-------
°l
CN
vO
CO
w
E-i
CO
Q
w
H
BUTTON
H
CO
PM
P-i
CO
CO
H
Ch
CO
,0
CO
H
CO
T)
O
O
CO
CO
^
CO
0)
J-l
PQ
vO
OO
CTi
CO
J-l O
o o
a »
X o
w o
o
0
0
o
o
o
o
o
o
10
i-l •-< O
cfl a. o
H CO
P
a
3
w
O
0
3
COl
CO O
4-> O
H o
si
T3 *
O S
vO
vO
CN
CTi
CO
o
00
cu
PQ
CTN
CTt
CT»
. (U
CO J2
co
c m
cu o
o
3
cu co
&
CO -U
0)
3 O
PQ
co
cu u
w o
a
M-l CU
o >-i
co cu
•w f
cu o
j-i
6 "S
o co
J-l CO
M-l PQ
&
S
O -U
U CO
J-l
CO
CO CU
o a
3
T3 r-l
O CO
J-l CU
a, j-i
cu
4J CJ
CO
O J-l
cu
M-l ,d
o 4J
o
•H r-l
3 co
o* cu
cu fi
1 1
C CO
•H O
CO
VI <+-!
60 O
-a c
c o
CO -H
4-1
0 0
*rH 7
Cfl *X3
J-i 0
60 M
CO
CU 0
T3 -H
3
-1 T)
O
•
>,
CO 0
3 -H
ca e
d »H
CU r-l
O CU
£
•^
60
-------
General statistics of flour and other grain milling plants for recent
years are presented in Table 40. The percent of value of shipments accounted
for by the largest companies in (SIC) Code 2041 are shown in Table 41.
Wheat Milling - Flour milling in the United States is carried on by numerous
companies. Commercial flour mills are located in many states and Buffalo,
New York, is the nation's largest milling center. Buffalo is, in fact, the
world's largest. Table 42 shows the distribution of flour mills by state for
the year 1973.
Milling consolidations have resulted in several companies attaining
multiple plant operating status. The largest wheat flour milling companies
in 1973 are shown in Table 43, while Table 44 presents the top 12 milling
companies for the same year. Table 44 includes durum and rye products as
well as wheat flour. In 1973, as shown in Table 45, 24 mills with capacity
in excess of 10,000 cwt/day produced about 36% of the flour in the U.S.
In the same year mills with 5,000 cwt/day or greater capacity produced about
75% of the U.S. flour.
Reference 26 indicates that the flour production of mills of less than
400 cwt/day capacity is minimal and of small commercial consequence. A re-
cent triennial survey conducted by the Millers' National Federation indica-
ted that there were 189 mills in the U.S. in 1972, with daily capacity of
400 cwt or more. This is a decrease of 11 mills from the 1969 total and re-
flects a continuation of a downward trend that has been under way since the
1930's. Table 46 presents numbers of mills, total daily capacity, net
change in total and in percentage for 3-year periods in several federation
surveys ,~*L?
Durum Milling - In 1945, the center for durum milling was concentrated in
the Upper Midwest near the resource. Since 1945, the industry has become
more market oriented in that most new mill capacity has been built closer to
their markets. The Upper Midwest is still considered the center of durum
milling and maintains 68% of the milling capacity in the United States.
The number of durum mills has remained relatively stable over the past
25 years (Table 47). While the number of durum milling plants remained
stable since 1945, the size (capacity) of the mills has changed. Since 1945,
the small mills (0-2,000 cwt/day) declined from 27% of the total mills to 8%
in 1969 (Table 47). The number of large durum mills (8,000-10,000 cwt/day),
which were nonexistent in 1945, comprised 167o of total mill numbers in 1971.
Table 48 illustrates the geographical distribution of durum mills in 1971.
61
-------
1
c*j
£5
"^4
PH
M
1
25
M
O
03
o ^
^ o
u ^
J^ in
M vO
OT 2
1— I '
H ^
3
to
h-3
5*
w
H
O
.
O
(4-1
0
JJ
CO
0
u
(U
3
I-l
CO
>
to
S-I
(L)
S-*
O
12
c
o
•H
U
U
D
T)
O
CM
CO
CD
"
o"
o
TJ 0
01 .
s °
•g o
<3 o
s
o
CO °
§§
33 «
C CO
S S'
0) x~>
XI 0
e o
3 ^D
i-l 0
,-1 0
0 °
S-i "
CO 0
PL4 0
^
eu X-N
^Q ^D
S o
3 0
25 ^
J_J
CO
Q)
in cyi sj- . en r-» o
-* *:
i-i 1-1 1-1 1-1 i-i 1-1
oo cy* cn vo cn o^
• ••«••
m en i-i oo r~- cn
o cn cr» er\ c^ CM
*^~ *
• •
-------
H
0
d
5
rf
5
J
q
d
-i
H
Q
rf
D
I-l
1
-i O
3 r2j
D H
D rJ
J H
s< 21
o a
E! o
,
M
is M
o
n W
D g
D r5
1 S
> U
1
D
H
1
J
tf
4
lj
-1
d-
-i
Q
Cfl
-1
— .
o |
co
4-1
C
CU
S
a
•r-l
.fi
C/3
^.
J_)
4J
W
3
Tj
rJ
M
O
CU
3
r-l
Cfl
oj
>,
^2
rl
O
4-1
T3
CU
4-J
C
3
0
O
CJ
CO
4J
fi
CU
O
S-i
cu
fr
4J
CO
CU
0 60
in s-i
cfl
4-1
CO
CU
O 60
CN S-I
CO
,_3
4J
CO
cu
00 60
S-i
CO
4-1
CO
cu
a, ,
fi
CO
G.
6
o
CJ
o
4-1
C
•H
13
CU
N
•rl
S-i
CO.
H
g
3
CO
rjj
CU
CU
ft
cu
£>
CO
co
4-1
C
CU
e
co
•i-l
i— i
ft
CO
4J
en
CU
S-i
O
4-1
CO
i— 1
CO
4-1
0
4-J
4-1
fi
CU
6
••-i
rl
CO
4-1
O
cu
3
r-l
CO
.
CO
-rJ
S-i
o
o
CU
S-i
CU
si
4-1
C
•H
CO
4-1
C
CU
e
&
•rl
si
CO
4-1
O
cu
3
r-l
cfl
>
co
•,
J^
C
CO
g
O
0
t~t
a
CO
cu
^i
r>
13
cu
C
•H
cu
4-J
cu
13
cu
S-i
CO
CO
cu
•H
rj
Cfl
I1
o
o
—
"4-1
CO
cu
60
S-i
cfl
t 1
—
.
r*^
S-i
4J
CO
*o
fi
•1-1
60
fi
S-i
3
4-1
O
CO
4-1
I
£j
•
r*>
}-l
4J
CO
3
13
C
•i-l
'O
cu
•r4
4-1
•H
CJ
cu
pt
co
si
H
CO
S-i
cfl
cu
£*,
S-i
O
•r-l
S-i
a
TJ
fi
CO
r^
^o
i
en
vD
CT»
r-l
CO
^
CO
cu
^
CU
4J
fi
CU
CU
u
•4-J
0)
rQ
CU
r-l
/">
CO
S-i
CO
a
e
0
o
K^l
l-l
cu
4J
cu
r-l
p ,
£3
O
CJ
4-1
O
c
a)
S-i
CO
CO
CU
S-i
3
00
•rl
m
ca
4-1
C
cu
e
a
rl
CO
4-1
O
cu
3
r-l
CO
-01
e industry
si
4J
0
4-1
>,
S-i
CO.
g
•i-l
S-i
a.
co
4-1
O
3
T3
0
S-i
a.
4-1
o
01
3
i— i
cO
j>
/( — s
CO
^>
^i
4-1
ca
3
13
C
•H
CU
4-1
C
•H
-rj
cu
•l-l
L-l
•H
CO
CO
CO
r-l
O
CO
4-1
fi
cu
S
Si
co
•l-l
r-l
f,
CO
4-1
CO
cu
i— i
r-i
CO
S-i
o
4-1
CU
'O
3
r-l
O
c
•l-l
aneous
r-i
r-l
CU
O
CO
•rl
e
4-1
O
CU
3
i-l
CO
>
^^
O
x^
. »*
CO
CU
•i-l
S-i
4-1
CO
3
T3
C
••-I
j^
cu
si
4-1
O
o
4-1
^
S-i
CO.
£J
•r-l
S-I
o.
cu
S-i
CO
si
o
•i-4
si
CO
4J
O
3
•O
0
S-i
G.
^
^
CO
C
O
a
(U
co
i— i
i-i
CO
4-1
O
cu
3
r-l
CO
^^
,0
salable
«\
&.
cfl
S-i
CJ
ca
•\
CO
S-i
CU
JC
4J
O
>,
£>
13
CU
|5
O
co
r-4
CO
S-I
CU
4J
fi
O
v/
S-i
o
&
c
o
•rl
Cfl
CO
•i-l
cj
g
O
CJ
'O
fi
CO
4-1
o
CO
S-i
u
C
O
CJ
rJ
0
4-1
CO
4-1
a,
•i-i
CU
o
CU
S-i
CO
CO
Si
CJ
3
CO
co
4-1
G.
•l-l
cu
a
cu
S-i
C
1— 1
4J
si
60
3
O
ft
CO
CO
C
O
•l-l
4-1
•r-l
13
C
O
CJ
CO
S-i
Cfl
CU
S-i
O
•H
S-i
&,
•a
c
cfl
oo
m
CT*
r-l
O
m
S-i
o
o
ft
00
S-i
o
S '
CO
cu
•H
c
cfl
g
O
a
S-i
3
O
4-1
4-1
CO
CU
60
S-I
Cfl
1— 1
CU
Si
4-1
4-1
O
CO
4-1
C
£3
p ,
•rl
Si
CO
4-1
O
CU
3
i— i
CO
>
cu
si
4-1
4-1
O
6
3
CO
CU
Si
4-1
4-1
O
4-1
CO
•H
CO
fi
O
o
CO
cu
60
CO
4-1
C
cu
o
S-i
cu
G.
CU
.fi
H
^Jl
•
>.
4-J
CO
3
13
C
•!-<
cu
4-1
4-1
0
CO
4-1
C
CU
6
a.
•H
si
co
4-1
O
CU
3
r-l
CO
>
I— |
CO
4-1
O
4-1
CU
si
4-1
^
f>
*"O
cu
13
•H
>
•i-l
13
v\
,— x
CO
cu
•i-4
C
CO
&
O
CJ
63
-------
Table 42. WHEAT FLOUR MILLING BY STATES (1973)—
25/
State
Alabama
Arizona
California
Colorado
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Maryland
Michigan
Minnesota
Missouri
Montana
Nebraska
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Washington
Mills
1
1
9
3
2
1
2
6
1
1
7
8
3
21
9
1
9
11
8
3
7
1
2
13
17
1
15
4
4
37
1
7
1
18
9
12
19
4
Capacities
Active
7,300
1,000
38,600
15,200
472
2,000
9,500
5,950
2,200
720
53,360
23,440
18,100
115,250
4,065
400
20,600
75,260
79,240
12,000
33,170
4,600
700
86,600
19,730
5,000
68,525
22,200
23,000
33,881
6,000
3,800
3,000
33,860
27,040
27,720
17,874
27,750
in Cwt
Inactive
6,300
4,000
60
2,100
750
TOTALS
279
929,107
13,210
64
-------
Table 43. LARGEST WHEAT FLOUR MILLING COMPANIES^/
(With Active Daily Capacity of 10,000 Cwt or More)
Company
The Pillsbury Company
ConAgra, Inc.
ADM Milling Company
Seaboard Allied Milling Corporation
International Multifoods Corporation
General Mills, Inc.
Peavey Company
Nabisco, Inc.
Dixie-Portland Flour Mills
Ross Industries, Inc.
Bay State Milling Company
The Colorado Milling and Elevator Company
Centennial Mills
Cereal Food Processors, Inc.
Fisher Mills, Inc.
The Mennel Milling Company
Standard Milling Company
Sunshine Biscuits
TOTALS
Mills
8
17
8
8
7
8
4
3
3
4
5
4
3
2
1
5
2
3
95
Capacity
in Cwt
94,700
88,300
67,500
62,250
57,700
55,100
40,100
40,000
33,000
33,000
29,650
29,200
19,000
17,000
15,000
15,000
14,500
12,150
723,150
65
-------
Table 44. LARGEST WHEAT, RYE AND DURUM MILLING COMPANIES^5./
(With Active Daily Capacity of 10,000 Cwt or More)
Company
The Pillsbury Company
ConAgra, Inc.
ADM Milling Company
International Multifoods Corporation
Peavey Company
Seaboard Allied Milling Corporation
General Mills, Inc.
Nabisco, Inc.
Dixie-Portland Flour Mills
Ross Industries, Inc.
Bay State Milling Company
Colorado Milling and Elevator Company
TOTALS
Mills
8
17
10
11
5
8
8
3
3
4
5
4
86
Capacity in Cwt
94,700 W
88,300 W
79,500 WD
74,200 WDR
60,600 WDR
63,250 WR
55,100 W
40,000 W
33,000 W
33,000 W
31,850 WR
29,200 W
682,700
W - Wheat Flour.
D - Durum Products.
R - Rye Flour.
66
-------
25/
Table 45. RELATIVE SIZE OF ACTIVE AND INACTIVE^-'
WHEAT FLOUR MILLS (1973)
Cwt/Day
Under 200
200-399
400-999
1,000-4,999
5,000-9,999
10,000 and over
Number of
Mills
54
35
36
78
52
24
Total Capacity
Active
5,845
9,469
20,093
197,750
361,850
334,100
Inactive
60
250
500
12,400
-
"•
TOTALS
279
929,107
13,210
Table 46. CHANGES IN WHEAT FLOUR MILLS AND MILLING CAPACITY
1951 -
1969-72
1966-69
1963-66
1960-63
1957-60
1954-57
1951-54
No. of
Mills
189
200
217
226
245
256
278
Total
Capacity
(Cwt/Day)
952,135
927,080
951,800
955,400
943,515
932,835
916,735
Net
Change
+25,055
-24,720
- 3,600
+11,885
+10,680
+16,100
-96,370
Percent
Change
+2.7%
-2.6%
-0.3%
+1.2%
+1.1%
+1.8%
-9.5%
67
-------
^
H rH
O r^
< CTN
P-l rH
3 .
ON
co ON
rH
CO
rJ -
H vO
Oj
g
Pi rH"
B^D
ON
PH
O -
rH
O ON
H rH
H
pQ in
t-t •*
pj ON
EH rH
H
CN CO
PzJ
W H
32
H CO
*£
o w
W H
P-i !3
H
H cn
EH
^ §
-* PH
d) FTi
rH O
&
H
£
2
ON
vD
S
4-J
C
CU
o
CU
P4
1-1
<1>
B
3
4J
C
CU
o
oo i m
in i csj
CO
rH
ro O O r-»
* . * i .
00 O ir\ so
in CNJ I-H
O
O
O
rH
cn
i-H
r-i vD ro i CM
CM
r-H
CO
1— (
T-H
S
ro co CM r-* r-i
r*- \o oo o*» CJN
CM en r-i
O
0
o
rH
CO
rH
a
Cn
CM
-------
Table 48. DURUM MILLING BY STATES
State Number Capacity in Cwt
California 1 3,000
Louisiana^./ 1 1,000
Minnesota 5 29,400
New York 2 10,600
North Dakota 1 5,000
Oregon 1 5,000k/
Pennsylvania!/ 1 5,000
Wisconsin 1 9,000
Totals 13 68,000
a_l Under construction.
b_/ Alternates with wheat flour.
The durum milling industry is composed of a small number of companies
(Table 49), with the number of companies remaining quite stable over the
past 25 years. When evaluated by proportion of total industry capacity
operated by the largest firms, the durum milling industry may be considered
a highly concentrated industry. Since 1945, the two largest firms have held
from 36% of the industry capacity to a high of 54% in 1969. The trend since
1950 has been toward increased concentration of production and market share
in the larger firms.
Dry Corn Milling - The number of dry corn mills has decreased in recent
years, but the capacity has increased. In 1965, only 152 mills with daily
capacities of 50 cwt or more were operating or in standby condition in the
U.S. By 1969, the total of both degerming and nondegerming mills had de-
creased to 115. The listed capacities ranged from 25 to 20,000 cwt/day of
meal production.
Reference 33 indicates that 122 mills were in operation in the continen-
tal U.S. in 1971, and Table 50 illustrates the geographical distribution of
these plants.
The quantity of corn dry milled into grits, meal, and flour and for use
in breakfast foods followed a cyclical pattern between 1926 and 1955. Be-
cause more grits and meal were used for human consumption and in manufacture
of malt beverages, the quantity climbed appreciably between 1955 and 1965 as
shown in Table 51. Based on data from the 1967 U.S. Census of Manufacturers,
and conversion factors used by U.S. Department of Agriculture, about 807° of
the corn dry milled that year for corn meal, flour, grits, and breakfast foods
was degermed.
69
-------
Table 49. NUMBER, CAPACITY, AND CONCENTRATION RATIOS OF THE DURUM
MILLING INDUSTRY IN THE UNITED STATES, 1945,
1951, 1961, 1965,
Number
of
Year Companies
1945
1951
1961
1965
1969
10
11
10
Percent of Total
Daily Industry Capacity
and Amount in Cwt
Produced by:
Capacity
(cwt/day)
35,340
39,825
36,536
41,290
51,678
2
Largest
Compan ies
14,500
41%
14,500
36%
18,100
49%
18,200
44%
27,800
54%
4
Largest
Companies
22,300
63%
24,800
62%
26,450
72%
29,200
71%
40,800
80%
6
Largest
Companies
28,240
80%
30,800
77%
32,450
89%
35,900
87%
48,128
93%
70
-------
Table 50. GEOGRAPHICAL DISTRIBUTION OF DRY CORN
IN CONTINENTAL UNITED STATES(1971)
State Number of Mills
Alabama 3
California 2
Delaware 2
Florida 2
Georgia 5
Illinois 4
Indiana 4
Iowa 1
Kansas 2
Kentucky 13
Mississippi 3
Missouri 3
Nebraska 3
North Carolina 23
New York 1
Ohio 3
Oklahoma 1
Pennsylvania 4
South Carolina 4
Tennessee 18
Texas 6
Virginia 12
West Virginia 1
Wisconsin 2
71
-------
Table 51. CORN USAGE PATTERN IN DRY
CORN
Million Bushels/Year
94
87
86
98
92
88
106
126
133
132
131
Rye Milling - In 1973 there were 13 rye mills operating in the United States
with a capacity, based on 24-hr production, of 10,999 cwt/day. Table 52
shows the geographical distribution of these mills.
Characteristics and Trends in Grain Milling
One of the major technological innovations in wheat milling in recent
years was the development and adoption of fine grinding and air classifica-
tion milling. This enables the mills to obtain closer tolerance in protein
levels, particle size, and ash content of the flour. The fine grinding and
air classification equipment, coupled with running analyses on protein,
moisture, and ash content every few hours, enables larger plants to maintain
strict control of the quality of their products.
Pneumatic mills are gradually replacing the conventional bucket elevator
mill. Table 53 illustrates this transition for hard wheat flour milling plants.
72
-------
25/
Table 52. RYE FLOUR MILLING BY STATES (1973)—
State
California
Illinois
Minnesota
New York
Ohio
Texas
Washington
Wisconsin
TOTALS
Number
1
1
3
3
2
1
1
1
13
Capacity in Cwt
75
144
6,200
2,260
1,900
30
150
240*/
10,999
a/ Inactive.
73
-------
~ral
E-4
O
H
§
CQ
IS
O
M
H
3
H
CO
a
1-1
FH
0
w
g
H
H
M
a
o
M
H
a
PH
O
a
i— i
CO
H
l-l
§
O
a
M
,-J
M
a
rT|
o
CO
w
PH
H
^^
r--
CM
CO
in
0)
i— i
n
CO
EH
>J3
O
u
ON
m
ON
i-l
O
4-J
vD
•^
ON
i— 1
1
CO
CO
CO
r^t
u
M
<
1
g
>
C
0
U
m
VD
ON
i-l
O
O
"JO
ON
r-l
I
•H
CO
CQ
CO
i-l
U
r-l
•H
<£
1
C
01
>
C
o
u
C
o
•r-l
4-J
CC
G
•n
01
ooooooo ex
4^
0)
d
o
, — i
s
o
•H
4-1
.
CO
J3
'Oooooco^-mcM jj
CM r_| vo
dl
1-1
g
0
S3
c
3
01
d
Pu
"S
OOOOOOO p
o
a)
en
C
O
•H
^j
CO
•r-l
O
•I-l
4-1
4J
d
1
CO
•1-1
rH
rHOOOOOrH X)
CO
4J
CO
a)
4)
g
CO
C
O
4J
O
CO
CO rH O rH O O in
CO
4-J
a
Ol
o
*H
4-J
i
C
Ol
C
PM
g
CO
•H
COrHCOOOOr-- rH
CO
4J
01
60
C
O
•H
4-1
CO
U
•i-l
"4-1
C
•H
rH
•H
e
CMrHOrHOO<)- IH
3
0
, 1
U_f
4J
cfl
i— 1
§
O
•H
4J
QJ
ooooooo
j_,
CO
JS
o
•H
] i
3
dl
C
PH
r^
CT«
^^ t~"l CO C**J ^^ i—4 Lf"i O
rH CM
CO
01
CO
G
O
rH P,
CO CO
0 4J dl
•HOC (-1
rH rH 4J -H H
ro ca cJ 4J c
>J M CO C [>, 0
•U 4-1 rH [rj QJ
C C 4J rH > -0
0) d dl
-------
Wheat flour mills are often involved in a number of functions in addition
to the milling of flour. Other operations that might be conducted at a wheat
flour mill complex include corn milling, rye milling, oat milling, blending, and
mixing. Table 54 summarizes data on functions other than milling wheat flour
performed at plants during the 1964-65 marketing year.
The grain milling industry as a whole seems to be following a pattern of
a decrease in number of mills with modest increases in capacity. The industry
appears to be either a stable or declining industry. With the exception of two
or three firms, there has not been much dramatic growth in individual firms.
The growth of the exceptions was mainly by acquisition. In addition, some of
the leading firms have had substantial declines in their value as a part of
corporate strategy.
Most grain millers, because of the nature of their business, are automati-
cally in the grain business. Similarly, the by-product of milling operations
(mill feeds) puts them into the feed business.
COMMERCIAL RICE DRYING
Introduction
The rough rice drying and storage section of the rice industry is ex-
tremely important to rice producers, and a significant share of the marketing
bill is spent for this service. An indication of the importance to rice grow-
ers and others of efficient, low-cost drying and storage of rough rice is re-
flected in the amount expended for these services. Of the $200 million re-
ceived in 1966 for rough rice by growers in Louisiana and Texas, for example,
an estimated $12 million or 670 of the value, was spent for artificial drying.
The cost of storage, though not generally borne as directly by growers,
no /
probably amounted to another $5 million.—' The structure of the commercial
rice drying industry is summarized in the following section.
Industry Structure
More than 400 firms were in operation with drying and storage facilities
for rough rice in the continental U.S. in 1967.li/ In Reference 29, both
commercial and on-farm dryers were included. Commercial dryers are facil-
ities available to the general public for the receiving, drying and storing
of rough rice. On-farm dryers are privately owned facilities used primarily
for drying and storing rice at points of production, and were not considered
in this study. A complete survey of rice drying establishments has not been
conducted since 1967, and the exact number of plants in operation in 1973 is
not known. Reference 29 indicates that in 1967, Arkansas had over 125 firms
75
-------
1
I
H
£
3
H
-1
c
a
q
H
2
3)
3
LJ
M
£
D
:>
^ >
-t <£
I"
E O
J3 M
H W
-3 S
H <;
3 S
5 m
3 |
^D
tf C7N
4 rH
S
H
3
O
z
D
H
-H
J
5
D
i,
.
;j-
n
CU
-H
D
CO
-H
- —
col
T3
g
l-i
O
CM
p
0)
PM
tn
pj
O
4J
CJ
C
En
M
cu
x:
4-1
O
cu
XI
4-1
o
~tjl
OQ
•rl
X 01
al o
•r4
4-1
O
C
\ r3
od
ti
•v
c
0)
r-l
PO
M
•H
e
o
14-1
cu
PM
od
c
CU -i-l
OJ r^l
•I-l
JS
en
] 1
c
CO
r-H
PM
o
}^
ori
C!
C -H
V4 r-l
O r-l
O •!-!
a
0)
•i
3
od
e
T3 -13
CU r-t
PM *H
r^ co <± CM o r-il r-*
1 -1
O -J" -rJ U
4-1 E S O
O 3 O
^ ^ 0 &
i — . CM co in r^
-------
engaged in drying and storing rice. The storage capacity for rough rice
handled by these organizations ranged from about 19,000 cwt to over 1 mil-
lion cwt. Cooperatives handled over 6070 of the total drying and storing of
rough rice in Arkansas. About 20 organizations supplied the off-farm drying
and storage facilities for rice in California with the majority of them
equipped to handle volume production. Storage capacity of these firms ranged
from 47,500 cwt to over 3.3 million cwt of rice. Cooperative associations
dried one-fourth of the total rice produced in California. In Louisiana and
Texas, about 220 firms dried and stored rough rice. The number of firms was
about equally divided between the two states with storage capacities ranging
from about 16,000 to over 560,000 cwt of rough rice. Over 40% of the rice
produced in these states was dried and stored by cooperative associations.
Reference 30 reports the results of a study by the Department of
Agriculture to determine the costs of commercial drying, storing, and handling
of rough rice for the 1965-66 period. The USDA identitied 279 commercial
rice dryers in this study. Capacities ranged from less than 15,000 to over
3 million cwt. Most of the firms, however, had capacities of less than
250,000 cwt.
Characteristics of Plants
The study conducted by the USDA also acquired data on the operating
characteristics of commercial rice dryers by sampling selected plants. A
stratified, random sampling technique was utilized by USDA investigators to
obtain data on the operational characteristics of the commerical rice drying
units. Tables 55 to 59 summarize some of the results of the sampling.
Table 55 presents data on the number and total capacity of commercial
rice dryers. Table 56 summarizes information on total plant capacity and
utilization for rice handling and storing by regions. Other services such
as handling of rice planting seed, other grains, seeds, fertilizers, and
farm supplies were also provided by some commercial rice dryer operators.
In Arkansas-Mississippi, joint use is generally made of rice drying and
storing facilities with other grains, such as soybeans--a practice not ob-
served to any extent in the other two regions. To provide for intraregional
comparisons of average occupancy and capacity utilization rates, the total
plant capacity data for Arkansas-Mississippi were reduced to the portion
actually used for rice handling and storing during the 1965-66 season. As
a result, there were 9,382,000 cwt less than the capacity used in sampling
(Table 56). In Texas-Louisiana and California, similar adjustments were
unnecessary.
77
-------
Table 55. NUMBER AND TOTAL PLANT CAPACITY OF RICE DRYERS
UNIVERSE AND SAMPLE, BY REGION AND QUARTILE
GROUPINGS, 1965-(
Universe^/
Region and
Quartile Grouping
Combined regions
1
2
3
4
Total
Arkansas -Mississippi
1
2
3
4
Total
Texas- Louisiana
1
2
3
4
Total
California
1
2
3
4
Total
Population
No.
173
62
33
11
279
38
20
10
7
75
112
31
17
--
160
23
11
6
4
44
Capacity
(000 cwt)
17,991
18,179
18,446
17,571
72,187
3,631
5,748
5,568
12,857
27,804
11,492
9,017
9,372
--
29,881
2,868
3,414
3,506
4,714
14,502
Sample
Population
No.
9
8
8
7
32
2
3
2
5
12
5
3
4
--
12
2
2
2
2
8
Capacity
(000 cwt)
1,225
2,384
3,719
9,853
17,181
248
780
1,188
8,071
10,287
720
915
1,338
--
2,973
257
689
1,193
1,782
3,921
a/ Includes both drying and storing facilities.
b/ All commercial dryers in Arkansas, Mississippi, Louisiana, Texas, and
California.
78
-------
Table 56. ESTIMATED TOTAL PLANT CAPACITY AND UTILIZATION^0-/
FOR RICE HANDLING AND STORING BY REGIONS,
1965-661/
(000 cwt)
Plant Capacity
Total
Utilized for rice
Arkansas-
Mississippi
27,804
18,422
Texas-
Louisiana
29,881
29,881
California
14,502
14,502
Regions
Combined
72,187
62,805
a_l Sample dryers in each region statistically expanded to represent
universe total.
Table 57. ESTIMATED VOLUMES OF ROUGH RICE HANDLED, AT
•^o/
COMMERCIAL RICE DRYERS, BY REGIONS,—'
(000 cwt)
Handling Activity
Volume handled in--b/
Arkansas- Texas-
Mississippi Louisiana California
Regions
Combined
Received—'
Dried
Highest monthly inventory^/
Average occupancy^'
Loaded out.t/
20,512
20,000
13,410
5,023
14,700
39,534
36,236
21,236
9,041
31,605
16,023
14,024
10,617
5,766
12,103
76,069
70,260
45,263
19,830
58,408
a/ Sample data statistically expanded to represent regional totals.
b_/ All volumes adjusted to dry weight basis.
£/ Sample volumes expended to regional production totals.
d_/ Maximum volume of rice in storage at end of peak month of year.
e_/ Average volume of rice in storage during year.
fj Excludes volume moved directly to mills by conveyor systems and that
loaded out for shipment by barge.
79
-------
Table 58. RECEIPTS OF ROUGH RICE BY MODE OF TRANSPORTATION
COMPARED WITH TOTAL CAPACITIES, BY REGIONS,
1965-6610-/
(percent)
Volume
In farm-owned
In commercial
Compared with
Received
trucks
trucks
total capacity*?./
Arkansas-
Mississippi
99.8
0.2
111.3
Texas -
Louisiana
70.3
29.7
132.3
California
60.0
40.0
110.5
Regions
Combined
75.2
24.8
121.1
a/ Based on portion actually used for rice handling and storing in 1965-66.
In Arkansas-Mississippi, rice dryer-storage facilities were used jointly
with other grains.
Table 59. COMPARISON OF VOLUMES OF ROUGH RICE DRIED TO VOLUMES
RECEIVED AND TO TOTAL CAPACITIES, BY REGIONS, 1965-663-0-/
(percent)
Item
Volume dried compared with:
Volume received
Total capacity^/
Arkansas-
Mississippi
97.5
108.6
Texas-
Louisiana
91.7
121.3
California
87.5
96.7
Regions
Combined
92.4
111.9
a./ Based on portion actually utilized for rice handling and storing in
1965-66. In Arkansas-Mississippi, rice dryer-storage facilities were
used jointly with other grains.
80
-------
Volumes of rough rice handled are shown in Table 57, while Table 58 pre-
sents data on the mode of transportation of rough rice to commercial dryers.
The data in Table 59 indicates that over 92% of total rice receipts at commer-
cial dryers in 1965-66 for all regions combined were green and required drying.
A considerable quantity of dried rough rice was transferred to mills or other
storage facilities immediately after it was dried. Green rice passed through
the drying-tempering cycle an average of 4.1 times in Arkansas-Mississippi,
5.2 times in California, and 5.4 times in Texas-Louisiana, averaging 4.9
times. Dryer passes ranged from 2 to 8, depending upon: volume and moisture
content of the green rice, plant layout, and operating practices.
RICE MILLING
Introduction
United States rice production and milling is concentrated in relatively
small areas of Arkansas, California, Louisiana, Mississippi, and Texas. Minor
quantities are produced in several other states.
Rice processing, marketing, and distribution are important links between
the concentrated domestic production and widely dispersed consumption areas in
the United States. All the mills, except those in New Orleans and San
Francisco, are located in or near the areas of concentrated rice production.
Raw Materials and Products
Rice is the only raw material processed in rice mills, and milled rice and
various by-products are the products of the milling operations. Table 60 pre-
sents data on the supply and distribution of rough rice during the period 1949-
71, while Table 61 summarizes similar data for milled rice during the 1949-
70 period.
The quantity and value of shipments of products from rice mills in 1963
and 1967 are shown in Table 62, while Table 63 summarizes composite data for
recent years.
Industry Structure
Approximately 50 rice mills in the United States handle the annual rice
crop, but not all operate every year. The "mills are located in the producing
areas adjacent to the supply of rough rice. Table 64 shows the number of rice
mills operating in 1971 in the major rice-producing states and the range in
daily milling capacity.
81
-------
-OO * . K*.r,.,***»,n..>.*A**.H*«
W (/) i-t i-< .-I i-H T-( rH
o ocor^coooovoco^ococMincocoocoin-JcMinocM
H tfLninin^or^r^r".cocTioi>crioo
- y
col co inoo^^t^omomocoi—icocoo>'-'ii5O-r-HCOvDCOOOC^Or^iriO*iCT^COin^DCT\
o>v£jr^r^.mcOr-HOinr-^fO^CCT\
^f^^-d-Lri^o^ootntn^c^y^^r^-r^oocrvCTvoocriai
H •-! r-H
I
M
1^
u
D
a
. QJ
-------
tnooincMoocMoor^-coocMcncMcorsjtnt-'-J-oorooo
i^coocNifo^Oc^oQ.--i
-------
CN .—I CN "~l
O
4-1 O
O
T3
U~| CO <± en CN CN
oo o co m co oo
-xf rH CN vf i-*
CO
O
s
Cr
•§
O
U U U
CfJ P-4 pL| pL|
O 1) O
J-J CD i-i W
O 0)
0) ^H tU Fs
O O- O O
84
-------
Table 63. VALUE OF PRODUCT SHIPMENTS FROM RICE
Value ($000.000)
407.1
548.0
583.6
553.4
OQ/
Table 64. DISTRIBUTION OF RICE MILLS IN 1971—'
Milling Capacity
Number Range
of Mills (10 Ib, daily basis)
7 0.5-4.3
11 0.2-4
23 0.09-1.5
7
Many of the rice mills are owned by cooperatives, and the importance of
cooperatives in the structure of the rice milling industry varies among
states. A relatively high percentage of rice is cooperatively milled in
California (80-85%) and Arkansas (60-65%) as compared to Texas (20-25%) and
Louisiana (6-8%). Table 65 outlines the general structure of the rice mill-
ing industry in recent years. Table 66 presents data on the value of ship-
ments from the larger mills in the industry.
Very few new rough rice mills have been constructed in recent years.
However, many mills have installed new milling equipment, improved both
rough and clean rice handling facilities and made some renovation of the
basic facilities during the past 5 to 10 years. Modernization of new equip-
ment included bulk rice receiving, handling and storage facilities for both
rough and clean rice, new conveyors, bulk loading and the installation of im-
proved Japanese-made pearlers and rubber hullers. Some mills have also in-
stalled automatic processing controls and electronic sorting equipment. On
85
-------
4
1
H
3
3
3
•\
3
4
3
1
•j
3
3
•i
>
1
i
H
}
i
•1
3
i
1
3
\
>
'
)
i
i
13
O
U
CO
N T3
C co
CO
M rH
rl CO
0 p
•o
lt-1 -H
o p>
•rl
ET3
(3
O M
r-l
CO
M
0)
h-l
S3
O
•H
4-1
to
rl
0)
D
O
U-l
o
cu
D
£
CO
cu
cu
o
r-l
w
o
rl
cu
•§
3
H-l
O
rl
CU
g
3
a
43
O
a
•rl
n
CO
0)
13
4J
rl
CO
PM
0)
4J
Ct)
rl
O
a
rl
0
O
4J
•rl
C
CU
1— 1
II
•r-l
00
4-1
•rl
(3
•rl
4J
,— 4
g
,-^
O
o
o
CO
t— I
r-l
•rl
S
to
cu
C
co
a
3
o
u
rl
CO
01
o
in
oo
CO
m
m
co
vo
oo
in
r--
vo
t
oo
in
co
O
^1
^ 1
J,
M
H
K_l
CQ
cd
S X
tt!
Q EH
fa oo
H &
8 M
O CJ
< a
OT (J
H iJ
a M
w is
0, W
I-l U
BB M
c/i oi
I** a
O M
W OT
D H
I-J r-l
> <
hfe
0 0
0
S H
CJ W
D!j O
W D4
Pu ^
>J
S
cu
42
CO
H
to
4J
Shipmen
dustry
e
'—i
0
(U
3
CO
!>•
n
rl
O
M-l
•o
OJ
"^
D
O
CJ
0
4-1
(U
O
rl
cu
PM
4J
Cfl
(V
O 00
in rl
rJ
4J
CO
CU
O M
CN !-l
l_^
4J
to
0)
oo oo
3
•U
0)
,
r-l
Q
Q
8
rl
CO
CU
^
g+.g+^^^gg
*>*^ o^ ^^ Os CT^ ^^^ <^>>' s*^'
x— s ^~s x*\
-------
the other hand, the rice parboiling process is relatively new in the U.S.
and started in Texas on a commercial basis during World War II.
The attrition rate in rice mills has been rather heavy in recent years.
The reduction in the number of mills resulted from: (1) the "folding up"
of small, independent, family-owned and operated huller mills due mainly to
increased competition for rough rice supplies and clean rice markets; and
(2) the consolidation of milling facilities by large multimill firms by
closing up their smaller, relatively inefficient mills in outlying areas
and concentrating operations in the larger, centrally located, more efficient
milling operations.
Total milling capacity has not been greatly affected by the reduction
in the number of operating mills. The smaller mills usually are the ones
that have ceased operating. The remaining mills have increased their
average capacity as well as their total output during the past few years.
Characteristics of Mills
The typical mill in Louisiana normally operates only from August to
early May. Louisiana mills usually operate 24 hr/day during the peak fall
season but only if the clean rice is moving out every day. Lack of clean
rice storage space is the limiting factor with several mills and forces most
mills in Louisiana to move out the clean rice immediately after milling it.
During recent years, there has been a tendency in Louisiana mills to
integrate their services and functions backward toward the producer. They
have done this by erecting their own rough rice drying and storage facil-
ities and engaging extensively in green rice purchasing and drying and
storage operations for their own accounts. There are three basic reasons
why mills have found this to their advantage. First, they can do their own
blending and thus have better control over quality; second, there are cost
savings in rough rice hauling and handling operations; and third, they can
hedge on future price increase.
Texas mills normally operate year round with about half of them operat-
ing 24 hr a day and the remainder operating two shifts, or 16 hr a day. Like-
wise, half the mills operate 7 days/week and the others only 5 days. Texas
rice mills have expanded or integrated their operations forward toward the
consumer to a larger extent than has occurred in Louisiana. However, much of
the output in Texas is still marketed in wholesale-type packages or in bulk.
In Texas only two of the seven mills do not package milled rice in consumer
size packages under their own brand names which they advertise in major rice
markets.
87
-------
SOYBEAN OIL PROCESSING
Introduction
Soybean milling involves the crushing of soybeans into a wide array of
useful products. Processors convert a 60-lb bushel of soybeans into approxi-
mately 47 Ib of high-protein meal and 11 Ib of edible oil. Most of the meal
ends up as livestock and poultry feed, while some goes into the manufacturing
of soy protein products. The oil is used for margarine, shortening, salad oil,
paint, plastics and cosmetics.
Today, soybeans provide the world with its largest source of vegetable
oil and high-protein feed. Worldwide, more than 1.5 billion bushels of soy-
beans are produced annually, with the United States accounting for about 7570
of the total production. Other major producers are Mainland China, Brazil,
and the Soviet Union.
While soybean processing is one of the modern world's oldest industries,
its growth in the U.S. has been most recent, dating from 1911, when the prac-
tice was brought to California from the Orient and used imported beans. The
outbreak of World War I gave birth to a new industry in America and soybean
processing grew in earnest in the United States East Coast. By 1922, it had
spread to the Midwest with the opening of Illinois' first soybean processing
plant.
In a little more than 40 years, the soybean has risen from the bottom
of the U.S.'s agriculture crop ladder to its present position of being number
two. Corn is still the number one crop in terms of cash value to the American
farmer. Behind the growing importance of soybean growing and processing are
two attributes of the soybean seed: (a) a high content of protein, and (b)
a moderate content of oil useful for edible and industrial uses.
Today the U.S. soybean crop is produced on nearly 43 million acres in
at least 30 states. It is the only major crop registering acreage increases
during the last 20 years. Since 1949, over 30 million acres in the U.S. have
been shifted from other crops (mainly corn, cotton, oats and wheat) into soy-
bean production., The sharpest increases occurred during the 1960's.
Soybean Production
Soybeans have indeed found a place in American agriculture. In 1952,
soybeans ranked fifth in acreage among the major crops, and sixth in dollar
value and by 1971, ranked third in acreage and second in dollar value
(Table 67). It is evident from these figures that soybean production and
acreage has grown significantly since 1950. Acres harvested have increased
88
-------
-4
i-i 4-1
)-t C
O C8
O
P -GO-
TD
O CO CO
O 0) 4-1
one
- o cfl
i—I ^t
-------
300% while value of production has risen 450%. Total 1971 U.S. harvested
acreage was estimated at 42.4 million acres, while production was estimated
at 1.1 billion bushels (Table 68). The United States soybean processing in-
dustry continues to anticipate the expanding of output of soybeans as the
world's demand for soybean products increases.
Table 68. ACREAGE HARVESTED AND TOTAL PRODUCTION3-^
OF SOYBEANS FOR BEANS,1950-71
Year
1950
1955
1960
1965
1970
1971^
Acres Harvested
for Beans
(000 acres)
13,807
18,620
23,655
34,449
42,056
42,409
Total Production
for Beans
(000 bu)
299,249
373,682
555,085
845,608
1,123,740
1,169,361
aj Preliminary.
The Corn Belt (Illinois, Iowa, Indiana, Ohio and Missouri) historically
has been the main production area for soybeans because of the similar grow-
ing conditions required by both corn and soybeans. However, new varieties
better suited to new production areas with improved oil content and yields
have been developed widening the production area. In 1949, 707o of the soy-
bean acreage was located in the five states comprising the Corn Belt. In
1971, this percentage had been reduced to 51%, even though acreage had risen
from 9 to 22 million acres. The Delta States (Arkansas, Mississippi and
Louisiana), the Lakes States (Minnesota, Wisconsin and Michigan) and the
Atlantic States (North and South Carolina, Virginia, Maryland and Delaware)
have all increased soybean acreage significantly.
90
-------
The U.S. production of soybeans is expected to double again in the next
decade as the world shortage of protein and fat becomes more acute with the
anticipated increase in population and income levels. Researchers are de-
veloping new varieties and better weed, pest and disease control, and they
are hoping to increase yields of soybeans in all production areas.
Characteristics of the Soybean Milling Industry
Number of Plants and Capacity - According to an ERS survey, there was an
estimated 130 soybean mills operating in the U.S. in 1970 with an annual
processing capacity of 825 million bushels (Table 69).—' Since 1960, a
significant (57%) increase in processing capacity has been accomplished
with only a 4% increase in the number of processing mills crushing soybeans.
These figures differ somewhat from the Census of Manufacturers data issued
in 1967 in that the ERS survey includes cottonseed and other oil seed mills
that process significant quantities of soybeans. Thus, in 1967 the Census
of Manufacturers identified 102 processing mills, while the ERS survey in-
dicates 135 mills.
The soybean processing industry has historically had a record of a high
rate of utilization of production capacity. In 1960, the ratio of utilized
capacity to total capacity was approximately 77%, and in 1969 the average util-
ization rate per mill was close to 92%. Average processing capacity per mill
in the U.S. has grown approximately 50% during the last decade, increasing
from 4.2 million bushels to 6.3 million bushels. The dramatic increase in
domestic processing capacity in recent years is a reflection of the industry's
confidence that world demand for soybean oil and meal will continue to rise,
and that U.S. soybean products will remain competitive in world markets.
Thus, the soybean processing industry will accommodate further growth in demand
for soybean products in the 1970's and increases in capacity are anticipated.
Location of Soybean Oil Mills - The expansion of soybean production areas is
the main determinant of the location of the domestic soybean crushing industry.
In 1958, about 58% of the soybean oil mills were located in the North Central
Region, with the largest concentrations of plants located in Iowa and Illinois.
By 1970, however, this share fell to about 42%. The Delta States (Arkansas,
Mississippi and Louisiana) have increased their processing mills from 18 in
1958 to 30 in 1970 and now account for 30% of total. Table 70 shows the num-
ber of mills by state for selected years from 1951 to 1970. The leading U.S.
processing center is Decatur, Illinois, where more than 180,000 bu of soy-
beans can be processed daily. Memphis, Tennessee, is second in crushing
capacity, followed by Mankato, Minnesot-a.
91
-------
CO
w
H
<
H
CO
Q
Cd
H
g
CD
w
H
g
M
K*"*
H
h- 1
U
CM
U
0
M
CO
r_/3
w
u
ttJi— 1
P-i ro
O
Q r-
2; i
<; o
co ON
rJ rH
(—1
a
t 1
I— 1
0
m
r«
O
CO
0
6
.
vO
0)
r-l
CO
H
r-l
i— 1
g
0)
PL1
CU
w
cfl
!>
* T3
4J CU
•r-l N
O -H
Cd r-l
CL .H
CO 4-1
u CD
rQ
O
0
O
ft
O
O
o
00
d >
•rJ. 4J
CO -rl
CO O
CU cfl
o a
o CB
3
^
O
o
o
0
0
0
^_x
>4H T3 rH
O CU Cfl
N 4-1
0 -H 0
•H rH H
II I
+•* *rH
Cfl 4J O
Pi & H
4-1
c
01
0
CU
p-1
^
3
r^
•t!
O
cfl
Q.
ca
o
M
c
•r-l
CO
CO
0)
O
o
J-l
p-1
rH
C8
fi
C
iH J-J
>-l 60 0.
01 01
M C/3
CM
T3
0)
01
CO
rH
•H
O
M
Ol
-C
4-1
O
T3
c
Cfl
T3
01
01
en
c
o
4-1
4J
O
o
CO
0)
•a
3
o
h-l
.
ca
c
0
•r-l
4J
CO
I-H
0
a<
j-i
0)
4-1
C
•H
a.
CO
CO
0)
•H
J-l
0
4J
o
cu
£_J
•r-l
•o
01
T3
cd
J-l
4-1
•a
G
(0
cO
4-1
cfl
10
CO
3
CO
c
01
O
Q
0
M
MH
CO
C*3
w
^
rO
""O
CU
a.
o
r— 1
<1)
^
cu
T3
ca
0)
4-J
cO
e
•H
4-J
CO
W
«
ca
c:
cfl
CU
f^
r^>
O
CO
(4-1
O
ca
0)
•H
4J
•iH
4J
cfl
3
u-
4-1
C
Cfl
O
•H
14-1
•iH
C
60
•rH
ca
CO
en
cu
u
O
j-i
CL
4J
CO
rG
4-1
ca
i-H
i— 1
• rH
G
^j
CO
ca
4-1
01
^
O
CO
J-l
o
c:
•iH
Cfl
4-J
Cfl
°
<-;
rH
rH
J-l
a.
CU
u
CU
N-^
CU
4-J
(0
•o
0
4-1
oo
LA
o>
rH
CO
CU
4-1
Cfl
3
•H
4J
CO
01
0)
T3
Cfl
M
H
•
T3
CU
J2
CO
3
o
r**t
rH
rH
CO
3
4-1
O
Cfl
CO
C
Cfl
01
43
r*^
0
CO
•o
o>
r~!
CO
3
M
O
^-^
T3
CU
N
•H
rH
•H
4J
3
CO
C
cfl
CU
43
O
ca
C
cfl
4-1
• rH
O
CO
Cu
cfl
O
r— I
CO
4-J
O
4-1
C
CU
01
5
4-1
0)
43
01
CJ
C
01
}_l
01
14-1
U-l
•H
Q
92
-------
J\
^
u,
w
S
^
E-1
C/J
S
£-*
rH
W-^
awi
H 6
r--
!3 ON
I-H r-l
CO rH
,J m
tJ ON
S"
**
h-J W
H W
O H
r, 2j
r*~l ™
•^ CO
W
PQ Q
S_| £••
0 <
CO
CO
fa E3
0 2
r-f
ttJ O
| S
5 -^
5*" CO
P^ H-t
Q
@
H
5
2
p~*
E-1
CO
w
o
^
QJ
ri
TO
o
r-
ON
rH
r- i-- rH r-H r-*l r-l co ino^-oocMCMm col ON! CM o
1 t-H| rH | CM| CM CO
rH . . 6-2 . f-5
LA
ON
rH
COr-COOrH|,tS C '•HtO
"OO-HCMrHO COCOfOCO-iSE rlrHO4J
O CtdtOn) -iHTJECOOO OCO CO
•r-!43J2-r(rHr*-'-'S-S a0.iHCd(U3j3Hll*-'-'JB~S
4-l4J4J£>0|>,tOO ••rllHj3(34Jt«(0.r4O -Q
CM3rlr-lrHH tHOOtdCq!rHXr-IH tU
tOOO-iHIDCU CUdlrHrHCUCU4>!gO J3Ofl4
rH
CN \D U~l -d- COl Ol rH r— H- rH rH |
t-J>
m
ON
rH O O -* ON| -*| ON I-- -03 COl \O| OO 1 Ol I-- O CO COl
CO CO rH rH | ONJ , i _H«rH» ._J
rH • «|H I— « • " *r^
•H D tfl -r4 D * D D.
ErHtO S H 0-«
..CO -H 14HCW4J « •»-" tl 'tt tO-HC
4J.H t« p^Q O JtirHOCO tOCOtO
^HO C 3W T3COMCOIO 4>0 COCO-H
(DC S O4-1^5CCUCdt84-IS-aCJS-S C-rlCO
CQ-iHCOvHOCOO tOCCOMO •• Id «0 1-1
rHS-a-HCOH CCrOH •£ td^tOS
CrHOCXi-r-l CU-rltdCU ™ 4-ltH.HO
SMMMOS ^gWS « rnogj
U rJ HQ
to 4J
rH
rH CU -O
•r-l 3 S
E 13 CO
T3 fH /— S
cu to • cu
l 4J
O C - CO
W CO
IH CU CO
CU 00 Ji rH
45 d -rl rH
4J -r4 rl >rl
O IH 4J E
3 CO
TJ *O U-l
C - O
to to to
CU CU IH
•U u rl CU
O -H
C -H 4J 4J
M 4J tB
0 CU E
CO 3 -H
T) X
CO 14-4 ^-^ O
CU O IH
•H 4-J CL
l-l rl C O,
O CU 10 CO
4-1 43 6
U S IH CU
CU 3 O 14
r4 C T3 tO
•rl
TO CU 00 CU
43 C P
CU H -r4 CU
•a E 43
CO O
ij • 0 C
-u co N rH CO
CO O .H CU
•U CO E 4J
n) to
TJ UH cu E
O E .H
CO O 4J
3 CO tO CO
co cu cu
C *H "
CU 4J t3 CU
O -r-l O 43 IH
•u T-l H <8
E C 4-i cu
O to tB >,
5-- r4 3 M
VOl CO 14-4 CT tU CO 00
CM| rH O. rH C
>, 4-1 O rH -H
rH C -rl 4J
c n) o s cu
•r404-l ^
01 -rl ti H H
B 14-1 .H CU tO
•H TJ E
TJ d 50 rH
CU 00 C O CU
CL -rl .rl 43
O co E >*-l 4J
rH O O
CU CO o 14H
> to oo o
CU CU CO C
CO • TJ O -U -H 00
rH CO O J3 rH C
rH « CO JH tO 4-J -H
•r( O
-------
Value of Products Shipped - The value of shipments of soybean oil mill
producers has risen sharply during the last decade, growing more than 131.5%
during the 1958-70 period (Table 71). Shipments of soybean cake or meal
represented about 64.4% of the total value of shipments, and soybean oil
35.5%. During the 1958-70 period, the value of shipments of soybean cake
grew more than 181.2%, while the value of shipments of soybean oil grew
77.7%. The growth in the volume of soybean cake and meal shipments has been
predicated on the use of this commodity for domestic and foreign livestock
and poultry feed. Feed manufacturers look to soybean meal as the basic
protein source for modern livestock rations. The substantial growth in soy-
bean oil shipments has been influenced by the expanding worldwide market for
soybean oil as an economical vegetable oil, and by American industry for
use in paints, waterproof cements, soaps, greases and lubricants, printing
inks and fabric coatings, and the American public demand for a high poly-
unsaturated food for diet-conscious millions.
Quantities and Types of Products Shipped - A variety of products are shipped
from soybean oil mills, but only two represent sizeable volumes, i.e., crude
soybean oil and soybean cake or meal (Table 72). Crude soybean oil shipments
in 1967 were 5.0 million pounds, a growth of nearly 46% during the 1958-67
period. Of the total crude shipments in 1967, 60.5% represented degummed soy-
bean oil, while 39.5% was not degummed. Other soybean oil products shipped
included once-refined soybean oil and soybean oil for inedible uses.
16/
Table 71. VALUE OF SHIPMENTS SOYBEAN OIL MILL PRODUCTS—
1958-70
($000,000)
Soybean Oil
Mill Products
Year Soybean Oil Soybean Cake n.s.k. Total
1970 756.9 1,370.7 1.2
1969 553.7 1,131.9 2.2
1967 594.3 1,143.4 3.1
1963 458.9 831.4 3.4
1958 425.9 487.4 6.4
Percent 77.7 181.2 ' -81.3
Change
1958-1970
n.s.k. = not specified by kind
'94
-------
Z) O
Jj -O O
HJ O O
_c i-i
S C
e o
3 o
-------
Soybean cake and meal shipments in 1967 totaled 12.9 million tons, up
59.4% from the 1958 total of 8.0 million tons. Shipments of cake and meal
represented about 92% of the soybean mill products shipped. Among the other
products are soyflour and grits, mill feed, lecithin, and other by-products
which represent only 8% of the total shipment of soybean meal products.
Nearly 92% of the crude oil is further processed for human food products,
such as vegetable cooking oil, margarine, shortening and salad oil. The re-
maining 8% is further refined for use in a wide variety of industrial products
(Table 73).
No other protein meal can match that of the soybean for efficient live-
stock production. As a result, nearly 99% of the nation's soybean meal is
fed to domestic livestock and poultry or exported for poultry and animal
feed. The industry offers soybean meal as either 4470 or 497<> protein base,
with few variations in between.
Competition with Other Protein Products - While at present, soybean meal is
the giant of the animal and vegetable protein world, the U.S. soybean indus-
try has other important competitors. Among the competitors are cottonseed
meal, fish meal, gluten feed and meal, and tankage and meat scraps. During
the past 10 years, domestic feed mill industry trends indicate a steady growth
of soybean meal, a static use of cottonseed meal, an erratic growth of fish
meal depending on fish catches, a consistent growth of gluten feed and meal
paralleling growth of the corn wet milling industry, a consistent increase in
meat scraps, in tankage usage, and the dramatic surge of urea from last to
second place among the major sources of feed protein.
Despite the forays of urea, soybean meal has maintained just a little
over one-half of the protein market. In the animal food area, soybean meal
may have to compete in the near future with expanded use of urea, protein
from petroleum and high-lysine corn.
On the other hand, some people see economic possibilities in using the
vegetable proteins directly for human food instead of our present practice
of feeding the vegetable protein to animals and then eating the animals.
Industry Concentration - The soybean processing industry has grown from a
large number of relatively inefficient, small mills independently owned into
today's modern industrial complex, mostly controlled by a small number of
comparatively large companies. In terms of value of shipments, the larger
firms are accounting for a growing share of the production. In 1958, the
four largest soybean processors accounted for about 40% of the total value
of shipments in the industry, and by 1970, the four largest processors
accounted for 56% of the value of shipments (Table 74). The eight largest
firms accounted for 73% in 1970, compared to 63% in 1958.
96
-------
_lj
o|
E-i
U
£3
Q
O
QJ
CX,
fa
O
W
W
OT
M
U
^-f O
PQ r>.
i
!S oo
O m
M ON s^
H r-l ,0
M M O
r4 W O
MHO
H <3 •
J3 H O
CO O
r4 O
M P -^
O W
H
S3 H
>> O 13
O l-i O
Q S-i
fri
r*- co CM co
m r^ r-i oo
i— i
4-1 1
C H J2
•H CO CO
CO > -r4
O-< 0
r-i O \o in
O O ON OO
' r-l r-l
oJ
to] Jj O O O
W
CO
U
o
a
13
O
D-i
*U
O
O
fa
r-l
CO
4-1
O
H
-3 oo CM o
CM 00 00 O
00 r-l r-l r-l
«\ •* t\ »\
CSI CO ^Cf ^O
M
0>
J3
4-1
O
ON ^J- ON oo
ON r-< O\ O
vo ON in in
n «*
r-l CM
1
•M W
M C
O -H
J2 C
W OJ
in ON r-l CM
in vo r-- oo
O r-l
oo o in o
in vo vo r^*
ON ON ON ON
i— 1 r-l rM r-l
•
rQ
I-l
0
O
0
o
m
a
CO
rC
•U
CO
CO
0)
rJ
— ^
Cfl|
97
-------
Table 74. PERCENT OF VALUE SHIPMENTS ACCOUNTED FOR BY-
THE LARGEST COMPANIES IN SOYBEAN OIL MILLING
1958-70
Value of Industry Shipments
Percent Accounted for By
4 8 20 50
Companies Total Largest Largest Largest Largest
Year (number) ($000,000) Companies Companies Companies Companies
1958 66 999.2 40 63 86 99
1967 60 2,148.3 55 76 94 100
1970 NA 2,609.9 56 73 NA NA
Integration - The large firms often own and operate several soybean mills
(horizontally integrated) while others may extend their operation by verti-
cal integration into vegetable oil refining and food and feed manufacturing.
The increased integration is illustrated by the increase in multiplant opera-
tions from 68 in 1958 to 73 in 1967 and the significant decrease in single
plants from 49 to 29 during the same period (Table 75). Several of the do-
mestic soybean processors have their own terminal and country or subterminal
elevators for the procurement of supplies and, in addition, have vertically
integrated forward into oil refining and salad and cooking oils.
Corporate Structure - In 1967, the Census of Manufacturers indicated that of
the 102 soybean mills listed, 76 were corporate-owned, while only 15 were
operated on an individual or partnership basis. The 1967 Census listed 11
plants as neither corporate, individual nor partnership, but rather as
farmer cooperatives. According to the Farmer Cooperative Service, USDA,
there were 13 cooperative mills operating in 1968, and they accounted for 15%
of the total soybeans crushed. An additional 10% of the soybean processing
was accounted for by cooperative-corporate joint ventures. During the last
10 years, the trend has been toward greater corporate ownership of soybean
mills, with corporations operating more than one mill.
98
-------
Table 75. TRENDS IN CORPORATION STRUCTURE IN THE—/
SOYBEAN MILLING INDUSTRY 1958-67
A. Type of Operation
Year Total Multi-Unit Single Unit
1967 102 73 29
1963 102 68 34
1958 117 68 49
B. Legal Form of Operation
Individual &
Year Corporate Partnership Cooperatives
1967 76 15 11
1963 73 18 11
1958 94 12 11
CORN WET MILLING
Introduction
The history of the corn wet milling industry is one of consistent, sub-
stantial growth and development, accelerating as new uses are found for its
diverse products. As present uses expand, new uses are also being devised,
including: the further utilization of starch in the metallurgical industries;
the use of starch as an integral part of paper, not only as sizing; the de-
velopment of wood-like structural materials using starch; and the utilization
of starch in insecticides and defoliating formulations. The industry has also
continued to mechanize and experiment to meet the demands of customers for
existing products and to cooperate with those interested in engaging in ex-
perimental projects.
99
-------
Raw Materials and Products
The corn wet milling industry processed over 225 million bushels of
corn in 1970 into a myriad of raw and finished products including starch,
syrup, dextrose and corn oil, each of which has literally hundreds of food
and industrial applications.
The corn refining industry is a year-round purchaser of corn, and an
important contributor to the economies of the Corn Belt States, as reflected
in Table 76 which was compiled by Dun and Bradstreet, Inc., for the Corn
Refiners Association, Inc. This exclusive survey covers the member companies
of the Association--the major manufacturers of corn starch, syrups and sugars,
oil, gluten feed and meal and related products from corn in America.
32/
Table 76. CORN PURCHASING PATTERNS FOR MAJOR FIRMS—
IN CORN WET MILLING INDUSTRY
A. Site of Purchase
Source
Farms
Country Elevators
Terminal Elevators
Government Stocks
1967
6.0%
79.1%
14.4%
0.5%
1968
7.5%
78.6%
13.5%
0.4%
1969
8.2%
81.0%
10.5%
0.3%
B. Percent Purchased by Selected States
State
Illinois
Iowa
Indiana
Nebraska
Missouri
Minnesota
South Dakota
1967
50.7%
32.7%
9.6%
1.1%
4.5%
0.8%
0.6%
1968
56.5%
28.7%
9.3%
1.4%
3.2%
0.6%
0.3%
1969
49.1%
34.3%
12.6%
0.8%
2.0%
0.8%
0.4%
100
-------
Table 77 presents data on industry shipments for the period 1957-66.
The data in Table 77 reflect only the activity of members of the Corn
Refiners Association, Inc. Table 78 summarizes detailed data reported by
the Bureau of Census on the quantity and value of shipments by all producers
.n 1963 and 1967, while Table 79 presents composite data for the value of
shipments over the past 25 years.
Industry Structure
The domestic corn wet milling industry is comprised of some 17 plants.
Of the 17 manufacturing facilities, nine were constructed in the early part
of the century with an average age of over 60 years; two were constructed
in the late 1940's and early 1950's and the other six were constructed within
the last decade. The older plants are largest in size and represent over 77%
of the industry processing capacity. The next oldest group has about 8% of
the capacity, and the last group of six plants less than 157o. Originally,
plants were located in rural areas, but today only one plant in the second
group and two plants in the last group can be so classified—the others hav-
ing become surrounded by metropolitan growth and development.
Table 80 presents general statistics from the Census of Manufacturers
for all establishments under the Census of Manufacturers SIC code for starch
manufacturing. This SIC code includes corn, wheat, rice, and potato starch
processors. While the data in Table 80 do not represent only the corn wet
milling industry, a comparison of the data in Tables 79 and 80 indicates that
the corn wet milling industry has accounted for 857, to 9070 of the value of
shipments from starch processors in the last decade.
Characteristics of Plants
The corn wet milling industry dates to the early 1900's. Many of the
older plants have undergone extensive modernization in recent years in order
to increase production and expand product lines. Plants range in processing
capacity from about 12,000 bu/day to over 100,000 bu/day. The 12,000 bu/day
plant, one of the newer facilities, is considered minimum size for the U.S.
A number of plants in the U.S. are in the 50,000-70,000 bu/day range, while
a few are in the 30,000-40,000 bu/day range.
Two old facilities were shut down in the last few years. These were the
Marschall Division Plant of Miles Laboratories in Granite City, Illinois, in
early 1972, and the Anheuser-Busch, Inc., plant in St. Louis, Missouri, in
December 1968. The combined annual capacity of these abandoned facilities
was approximately 22 million bushels.
101
-------
O ro
^ CNI en
i~* CO ^-1
-------
Table 78. QUANTITY AND VALUE OF SHIPMENTS BY ALL PRODUCERS IN CORN
WET MILLING INDUSTRY, 1967 AND 1963*— *
Product
WET CORN MILLING PRODUCTS, TOTAL
Corn syrup, unmixed:
Low (28 to 37 dextrose equivalent)
Regular (38 to 47 dextrose equivalent)
Intermediate (48 to 57 dextrose equivalent)
High (58 to 67 dextrose equivalent)
Extra High (68 and over dextrose equivalent)
Corn sugar (crude and refined):
Hydrous dextrose (including crude type)
Anhydrous dextrose
Corn syrup solids (dried corn syrup)
Cornstarch, including milo:
In packages larger than 5 pounds
In packages of 5 pounds or less
Other starches :
Potato, Irish
Other starches (wheat, rice, etc.)
Dextrin (corn, tapioca, and other)
Crude corn oil
Refined corn oil
Wet process corn byproducts:
Steepwater concentrate (50% solids basis)
Corn gluten feed
Corn gluten meal
Other wet process corn byproducts
Other wet process corn byproducts, n.s.k.
Other wet process corn byproducts, n.s.k.
1967
1963
Quantity
(000,000
(X)
(X)
Quantity
Value (000,000 Value
($000.000) lb) ($000.000)
647.0
(X)
0.3
(X)
547.2
1
1
3
210.5
,423.0
175.0
908.8
60.6
,227.9
127.1
,119.0
121.3
168.7
a/
78.0
2,365.9
875.2
341.4
(X)
10.5
66.6
8.3
43. 2^1
2.8 J
81.6
10.4
199.5
11.0
16.0
76.4
1.5
55.1
36.6
16.9
10.3^1
89.4
1,200.5
128.4
843.0
1,093.6
110.4
J2.498.3
i 66.8
j 132.6
\ 102.8
118.9
a/
42.7
1,316.8
1,078.2
(NA)
(X)
4.5
60.1
6.4
42.5
71.5
8.8
169.2
8.1
8.7
9.2
9.9
60.9
1.0
27.4
33.3
17.2
8.6
a/ Quantity data are withheld due to duplication arising from shipments between establish-
ments in the same industry classification.
* Total shipments including interplant transfers.
103
-------
Table 79. VALUE OF SHIPMENTS BY CORN WET MILLING^
PLANTS IN LAST 25 YEARS
Value of Shipments
Year ($000,000)
1947 422.0
1954 436.0
1958 482.6
1963 547.2
1964 546.5
1965 617.8
1966 654.8
1967 646.6
1969 697.9
1970 728.0
104
-------
CO T]
4J C
•H Ol
cx a
to X
CJ W
CJ
O
3 O
CU O
z -
o
O
o
01
00
cu to
to 4-1
01 C
.C 01
H O
r4
0)
e
0
B
cc
u
H
CO
Pi
O
C/3 00
u in
M t^
H r-l
CO
H
<
t/5
w
o
o
oo
to
H
CO ^-*
4J o
C o
cu o
B
ex o
O
O
cu
-H
> CO
0)
3
rH
to
>
X
ja
•a
01
T3
•a
i
CJ
CO
3
C
CO
01
lj
3
4J
O
O
O
o
o
o
>^
01
^
3
CO
rH
CO
3
ti
C
0)
01
.C
4-1
C
t)
cu
to
CO
CO
to
o
CO
4-1
rj
01
B
.C
CO
•1-1
^
CO
4J
CO
CU
MH
O
CU
rH
CX
E
to
CO
01
_r*]
H
.
to
4J
C
0)
S
CO
•iH
t-H
42
to
CO
C
to
o
cu
4-1
01
r— (
CX
B
o
o
to
o
CO
4-1
r-l
3
CO
o>
^
0)
4j
B
0
n
^
rH
CU
•H
4J
O
CU
CX
to
cu
n
rH
•o
C
CO
l-H
Ol
01
S
•0
Ol
T3
•o
CO
CU
3
rH
to
•O
c
S
1 1
C
Ol
S
o
T— f
CX
E
01
^,
o
CO
CU
•H
4-1
tO
T— 1
o>
M
m
vO
CJ*
^-1
v£)
vO
O"i
I-H
•o
01
4-1
O
01
•o
rJ
01
CX
to
o
cu
4_!
<4H
O
T-H
0)
rH
_n
tO
H
C
•H
r.
W
J_l
CU
3
4-1
o
03
14-4
3
C
CO
a
MH
0
CO
3
M
C
O)
CJ
rO
^O
r- 1
n
1— 1
M
-------
The processing capacity of the abandoned plants will be replaced by
two new corn wet milling facilities recently constructed. Cargill, Inc.,
will complete construction of a plant at Dayton, Ohio, in 1973. The facil-
ity will have a daily processing capacity of 34,000 bu, equal to about 11
million bushels/year. A. E. Staley began operation of a plant in Morrisville,
Pennsylvania, in 1972. The plant will process about 9 million bushels/year.
The Staley plant is the first of its kind on the East Coast, and one of only
a few located outside the Midwest.
106
-------
CHAPTER 2
REFERENCES
1. Agricultural Statistics. 1972, U.S. Department of Agriculture, Washington,
D. C.
2. Wheat Situation, February 1973; Fats and Oils Situation, February 1973;
Feed Situation, November 1972; U.S. Department of Agriculture,
Washington, D. C.
3. Goldberg, Ray A., Agribusiness Coordination, A Systems Approach to the
Wheat, Soybean, and Florida Orange Economies, Harvard University,
Boston, p. 112 (1968).
4. Agricultural Markets in Change, U.S. Department of Agriculture, Economic
Research Service, Ag. Econ. Report No. 95 (July 1966).
5. Published reports and private communications from individual grain ex-
changers and boards of trade.
6. Waterborne Commerce of the United States, 1966 and 1971; U.S. Department
of the Army Corps of Engineers.
7. U.S. Department of Agriculture, Kansas City ASCS Data Processing Reports.
8. U.S. Department of Commerce, U.S. Census of Business, 1948-1967.
9. U.S. Department of Agriculture, Economic Research Service yearly surveys
(unpublished data).
10. U.S. Department of Agriculture, Economic Research Service Report 501.
11. U.S. Department of Commerce, U.S. Census of Business, 1967.
12. Eckstein, Otto, "The Southwestern Miller, Breadstuffs Seminar 1972," p. 98.
13. U.S. Department of Commerce, U.S. Census of Business, 1963.
14. U.S. Department of Agriculture, Farmer Cooperative Service, "33rd Annual
Report of the Regional Grain Cooperatives."
15. Robert Morris Associates, Annual Statement Studies, 1972 Edition.
107
-------
16. U.S. Department of Commerce, Annual Survey of Manufacturers, 1970.
17. "The Formula Feed Industry, 1969--A Statistical Summary," Statistical
Bulletin No. 485, ERS, USDA, Washington, D. C. May 1972.
18. Feed Situation Report, U.S. Department of Agriculture, November 1972.
19. American Dehydrators Association Chart developed from production figures
supplied by the U.S. Department of Agriculture.
20. "1971 Supplement to Feed Statistics," USDA/ERS Statistical Bulletin
No. 415.
21. "Feed Market News," Consumer and Marketing Service, USDA.
22. U.S. Department of Commerce, Bureau of Census, Flour Milling Products,
Summary for 1971, April 1972.
23. Berger, D. W. and D. E. Anderson,"Analysis of Production, Processing,
Consumption Markets for Durum Wheat," North Dakota State University,
Agricultural Economics Report No. 77, October 1971.
24. Shaw, M., "Rye Milling in the U.S.," Bulletin of Association of Opera-
tive Millers, November 1970.
25. "Directory of Mills and Milling Executives, September 1973," Milling
and Baking News, Vol. 52(31), September 1973.
26. Southwestern Miller. July 25, 1972, page 13.
27. "Organization and Competition in the Milling and Baking Industries,"
Technical Study No. 5, National Commission or Food Marketing, June
1966.
28. Goodwin, M. R., and L. L. Jones, "The Southern Rice Industry," Texas
A&M University Press, 1970.
29. Directory of U.S. Rice Mills, Rice Journal, June/July 1971.
30. Costs of Commercial Drying, Storing, and Handling Rough Rice, 1965-1966,
USDA/ERS Report ERS-407, May 1969.
31. Soybean Digest. Blue Book Issue, March 1972.
32. 1970 Corn Annual, Corn Refiners Association, Inc.
33. List of Flour Mills. Northwestern Miller, Miller Publishing Company,
September 1971.
108
-------
CHAPTER 3
PROCESSES AND EMISSIONS
INTRODUCTION
Grain handling, milling, and processing include a variety of operations
from the initial receipt of the grain at either a country or terminal eleva-
tor to the delivery of a finished product. Flour, livestock feed, soybean
oil, and corn syrup are among the spectrum of products emanating from plants
in the grain and feed industry.
There is a significant difference between atmospheric emissions arising
from grain and feed industry operations and those of other industries; namely,
the majority of emissions are due to raw material handling rather than raw
material processing. Furthermore, some of the sources are of a "fugitive"
type. That is, the emissions are those that become airborne because of in-
effectual or nonexistent hooding or pollutant containment systems rather than
those that penetrate an air pollution control device. Other characteristics
of emissions from the grain and feed industry are the intermittent nature of
many of the specific operations, and the day-to-day variability of emissions
from a specific operation.
The myriad operations that comprise the individual plants in the grain
and feed industry and the associated air pollution problems are presented in
detail in the following sections of this chapter.
GRAIN ELEVATORS (GRAIN MARKETING OPERATIONS)
Grain sold from the farm generally proceeds through a series of grain
storage facilities before it reaches the ultimate user. Grain elevators
provide the storage space and serve as collection and transfer points.
There are three broad categories of grain elevators associated with
grain marketing operations; country, subterminal, and terminal. —' The
primary function of country grain elevators is to receive grain from the
farms for future delivery to a secondary elevator or processor. Country
109
-------
elevators serve as the major outlet for grain sold from farms and are extremely
important in the grain-producing regions of the United States.
In general, subterminal elevators are located away from metropolitan areas
and are the only large grain-handling facilities in the immediate vicinity.
They tend to be large, but their capacity is an incidental characteristic.
Some subterminals are smaller than the largest country elevators, while others
are larger than some terminal houses. Subterminal elevators rely on country
elevators in their area to provide them with grain by either rail or truck.
The subterminal generally has transit privileges for grain. The manager sells
directly to terminal elevators, processors, and exporters instead of selling
to interior dealers or commission merchants. Many subterminal elevators have
facilities that were formerly available only in terminal elevators.
Terminal elevators are large elevators generally located at significant
grain trade centers. The function of the terminal elevator is to store the
grain without deterioration in quality and to blend it if necessary so as to
conform to the needs of buyers. Grain-handling operations are similar at the
country, subterminal, and terminal elevator, but the subterminal and terminal
elevators are usually the first to thoroughly clean, dry, separate, and store
the grain at proper temperature and humidity. Grain moving out from terminal
elevators is ultimately used for food, feed, export, or industrial purposes.
In the following sections, the discussion will consider only the country and
terminal categories with the subterminal elevators being incorporated into the
terminal elevator group.
Grain Elevator Operations
Country Elevators - The definition of a country elevator appears to be some-
what arbitrary. However, for the purposes of this discussion, a country eleva-
tor will be defined by the following characteristics:
1. Receives grain by truck only, primarily from farmers.
2. Receiving leg handling capacity of 10,000 bu/hr or less.
3. The stored grain is shipped out by truck and/or rail.
Country elevators range in storage capacity from 15,000 bu to more than
2 million bushels. These elevators receive and store the grain with sub-
sequent shipment to terminal elevators, mills, and other processing plants.
There are approximately 10,000 such elevators in the U.S. representing a
total storage capacity of about 2 billion bushels. In addition to storage,
the country elevator sometimes includes facilities to clean the grain or to
dry it or both..L_2/
110
-------
The grain received at the country elevator is primarily received from
the farms that are within a 10-12 mile radius. The trucks which transport
the grain from the farm to the elevator usually range in size from 50-300 bu
with the average capacity being 200 bu.
The country elevator often consists of upright concrete bins, but wooden
bins and flat storage are also common. A cut-away diagram of a representative
upright country elevator is shown in Figure 5. These elevators are usually de-
signed to make maximum use of gravity flow to simplify the operation and mini-
mize the use of mechanical equipment. The major piece of mechanical equipment
required is the bucket elevator, or "leg," which elevates the grain to the top
of the elevator where it is discharged into the distributor head and then di-
rected to the desired bin or into the scale for direct load out. The section
of the elevator which performs these functions is referred to as the "headhouse.
The first step in handling the grain after it arrives at the elevator is
to weigh-in the loaded truck. After weigh-in, the truck is driven to the un-
loading station which is often a drive-through tunnel in the center of the
elevator similar to that shown in Figure 5. The trucks are usually unloaded
by lifting the front end of the truck with an overhead wench system or hydrau-
lic platform. This causes the grain to flow out the opening in the back of
the truck from which it falls through a grating into the receiving pit hopper.
Following completion of the unloading and lowering of the truck, the truck is
driven back to the scales and reweighed to determine the quantity of grain
received.
The grain dumped into the receiving hopper usually flows by gravity to
the bottom of the bucket elevator (i.e., the elevator boot). In some cases,
the grain is transported from the receiving hopper to the boot by means of
belt, drag, or screw conveyors.
The receiving leg, averaging 5,000-7,500 bu/hr, elevates the grain to the
top of the headhouse where it is discharged through the distributor head. The
distributor head is positioned to direct the grain into the appropriate storage
bins or to the cleaning equipment. Grain received from the farm usually con-
tains a variety of impurities and a cleaning operation is sometimes performed
prior to sending the grain to storage bins. Various types of screens and as-
piration systems can be used to clean the grain.
To remove the grain from the storage bins for load out, it usually flows
by gravity back to the elevator boot and is reelevated and discharged through
the distributor. This time, however, the distributor may direct the grain in
any of three possible ways:
1. The grain may be directed to the interstice bin located directly
above the drive-through tunnel and the waiting truck may be loaded at the
same position where unloading takes place.
Ill
-------
Ijijbl fULi-tCrCK (KtTuCt-0 'C GRAIN 'T
HtAr) HOU'jf- PULLE-V ANI, u£G BEIT
LilSHIBUrOI' TRANSFERS Gf'AIN FkGM tL.fv
1O ANV &1,\1 AUTCWAUC XAi^L Ofe !'
U EANtK
DISrrilBUTOK SPOUTING
UPPtH SCALt HOPPt*
^5 BUSMtL AUTOMATIC OCAtt
LOWER SCALE HOPPEH-!1; 6USHEL
LOAD-OLT SPObF
CONCRETE LEG
LEG BELT AND BUCKETS
flfCTRIC MANLlTT
AtiD '
'i 61 f-
Figure 5. Diagram of upright country elevator.
112
-------
2. The grain might also enter the distributor and fall directly through
the load-out spout to a waiting truck or railroad car.
3. The grain is directed to a scale hopper, batch weighed in the scale,
and then released through a load-out spout to a waiting truck or railroad
car.
An alternate method of loading that is sometimes used is direct loading
from individual bins by means of spouts that protrude through the walls of
the bins. The usual procedure in this case is to use the scale hopper for
both trucks and railroad cars and the interstice bins above the drive-through
tunnel for trucks.
The design of many country elevators is similar to that shown in Figure 5,
but many often include an annex storage facility. This annex may consist of
several additional bins or a "flat storage" tank or building. In either case,
both of these usually serve only as extra storage capacity. This configura-
tion requires installation of a gallery belt and "tripper" to convey the grain
from the discharge of the receiving leg to the annex storage bins, and a
"tunnel belt" under the bins to convey the grain from the bins back to the
boot of the elevator leg.
Certain grains, especially corn, must be "dried" before long-term storage.
Elevators that receive grain for long-term storage are equipped with grain dry-
ing facilities. Grain dryers generally require the addition of a second leg
to elevate the wet grain from intermediate storage bins to the top of the
dryer, and a means of conveying the dried grain from the dryer back to the pri-
mary leg for elevation to final storage. Grain dryers come in a wide range
of capacities, and the size installed in country elevators is dependent upon
the quantity of wet grain that is expected to be processed. A typical instal-
lation would probably be one dryer with a capacity of 500-1,000 bu/hr.
Terminal Elevators - For the purposes of this discussion, a terminal elevator
is assumed to have the following characteristics:
1. Receives grain by truck and rail and may include receiving by barge
if located on a navigable river.
2. Receiving leg capacity of 35,000 bu/hr or more.
3. Grain shipped by rail, barge or ship.
Terminal elevators can be subdivided into at least the following cate-
gories:
113
-------
1. Inland terminal elevator--functioning as a storage or transfer house.
Some of the receipts or shipments may be by barge in addition to rail and
truck.
2. Export terminal elevator—located at a seaport. Receives grain by
truck and rail and possibly barge with shipments by ship.
Storage capacities in terminal elevators are typically in millions of
bushels. Capacities in excess of 50 million bushels have been built at a
single location. These can include bins added to an original structure or
storage in warehouse-type buildings—so-called "flat storage." The largest
capacity at a single location under one headhouse is 18 million bushels.
The primary sources of grain received at many terminal elevators are the
country elevators. One of the major functions of the terminal operation is
to receive the differing grades of grain from the country elevators and to
blend these grades so they are suitable for shipment from the terminal to
the processor or user.
Another major function of some of the terminal elevators is to receive
grain from surrounding country elevators and to ship this grain to other
terminal elevators. These are sometimes referred to as "subterminal eleva-
tors" and they usually handle large quantities of grain thereby gaining ad-
vantage of lower freight rates for large rail shipments or shipment by barge.
These elevators may handle up to 20 times their storage capacity each year.
The export terminal elevators receive much of their grain from inland
terminal elevators, and these grains are blended and loaded into ships for
export.
Because of the large storage capacity and high grain handling rates in
terminal elevators, belt conveyors are generally used to move grain in these
elevators. Figure 6 illustrates a flow diagram for a representative terminal
elevator. The steps in the grain-handling process at a terminal elevator are
similar to those in a country elevator. The first step is the unloading of
semitrailer trucks, box or hopper railcars and, in some cases, barges. The
truck unloading system usually consists of one or two (or more) drive-through
unloading sheds located alongside the elevator. The semitrucks are driven
into the shed and onto a hydraulic lift platform with the back of the truck
positioned over the unloading grate. The hydraulic lift is then raised to
tilt the truck and the grain flows out the back, through the grate, into the
receiving pit. The grain is transported from the receiving pit or hopper by
belt conveyor (or in some cases, by screw or drag conveyor) to one of the
belt conveyors or elevating legs in the basement of the elevator. The truck
receiving hopper may have a capacity of 1,000-1,200 bu which is sufficient
to handle the largest trucks.
114
-------
o
0)
,-4
0)
•H
3
>-j
(U
e
cfl
H
60
n)
•i-l
3
W)
•r-l
115
-------
Railroad cars are unloaded by spotting the cars over the grates that are
between the tracks alongside the elevator. Sometimes these car unloading
areas are fully enclosed, but more often they consist only of a roof over the
unloading area. The hopper cars are unloaded by opening the doors in the
bottom of the car and the grain flows through the between-track grating into
the receiving hopper. There are two variations in the hopper car unloading
systems. In some cases, the receiving hopper system is large enough that
the entire car can be unloaded without filling the receiving hopper. In other
cases, the receiving hopper is comparatively small and it quickly fills up and
blocks the bottom outlet of the hopper car. In the latter instance, the grain
continues to flow out of the car at the rate which the conveyor beneath the re-
ceiving hopper carries the grain out of the receiving hopper. This latter
type of unloading is termed "choke unloading" and can considerably reduce the
quantity of dust generated during unloading in comparison to the other unload-
ing system where all of the grain free-falls into the receiving hopper.
Boxcars are generally unloaded by some method of shoveling the grain out
of the car door from which it falls through the grating alongside the track,
into the receiving hopper. "Power shovels," consisting of a plowboard attached
to a mechanically driven cable, are often used for this purpose. At some ter-
minal elevators, where a considerable number of boxcars are received, they may
be unloaded by means of a mechanical unloader which clamps the car to a section
of track and mechanically rotates and tilts the car. With this system, the
grain cascades out of the car door into a receiving hopper. The grain is
transported from the receiving hopper to the basement of the elevator, usually
by means of a belt conveyor.
Barge unloading, where applicable, is usually accomplished by a bucket
elevator (marine leg) that can be lowered into the holds of the barges. At
the top of the leg the grain is discharged onto a series of belt conveyors
that carry the grain to the elevator proper. Capacity of the barge unloading
system at a terminal elevator can range between 18,000-75,000 bu/hr, although
the average is 25,000-30,000 bu/hr.
After the grain is unloaded from cars, trucks, or barges, and transported
to the basement of the elevator, it may go directly to the boot of one of the
legs or it may be transferred onto one of the basement conveyors that carry
it to the boot of the leg. These legs have an average capacity of about
35,000 bu/hr and a large terminal elevator may have up to four or more legs.
At the top of the leg the grain is discharged into a distributor, or some
system of movable spouts, so that the grain may be directed onto one of the
gallery belts, into a scale garner for weighing and load out, or into cleaning
equipment. If the grain is directed onto a gallery belt, it is conveyed
across the top of bins (gallery area) to a "tripper" which discharges the
grain into the proper storage bin.
116
-------
The grain may be withdrawn from one bin, or from several bins simul-
taneously, by means of slide valves at the bottom of the bins. The grain
falls onto a tunnel belt leading back to the legs. If the grain is to be
loaded out, it may enter the leg and be discharged to the scale garner or
may be discharged directly into one of the load-out spouts for railcars
or trucks. If it is to be loaded into a barge or ship, it may by-pass the
leg and fall onto the first of a series of conveyors that transport it to
the barge or ship loading spouts.
The loading of semitrailer trucks at terminal elevators is similar
to that at country elevators except that grain is loaded at a faster rate.
The loading area at terminal elevators is often partially enclosed, but it
is usually left open at both ends.
Hopper car loading is accomplished in much the same manner as truck
loading. However, boxcar loading is a different matter because a high
velocity must be imparted to the grain as it passes through the loading
spout in order to throw the grain to each end of the boxcar.
Barge or ship loading operations generally require conveying of the
grain from storage bins to special loading spouts. In most cases, these
loading spouts are located at barge or ship piers some distance from the
elevator itself.
Air Pollution Sources, Emission Rates, and Effluent Properties
Except for barge and ship unloading and loading operations, the country
elevator includes the same operations as a terminal elevator, only on a
smaller scale and with a slower rate of grain movement. The air pollution
problems of both types of elevators are similar and they will be discussed
in this section.
The main particulate emission sources in grain elevators are:
1. Grain unloading
2. Grain loading
3. Grain dryers
4. Grain cleaning
5. Garner and scale bins
6. Elevator legs
117
-------
7. Transfer points
8. Bin vents
Table 81 presents data on rates of emission of dust from grain-handling
and processing operations at terminal and country elevators.36,377 ^&
emission rates shown in Table 81 are based on limited data and should be con-
sidered as indications of potential emissions and not absolute values.
Table 81. PARTICIPATE EMISSIONS FROM GRAIN HANDLING AND PROCESSING
(Ib/ton of grain processed)
Lb/Ton Range of Emissions
Emission Source Processed (Ib/ton)
1. Terminal elevators
Shipping or receiving
Rail 1 (1-3)
Truck 1.4 (0.8 - 3.5)
Barge 1.2 (1 - 3.5)
Transferring, conveying, etc. 2.0 (2-2.5)
Screening and cleaning 5.0 (5 - 7)
Drying 5.5 (4 - 8)
2. Country elevators
Shipping or receiving
Rail 4 (3-8)
Truck 4.5 (2 - 8)
Barge 5.5 (3 - 8)
Transferring, conveying, etc. 3.5 (2-4)
Screening and cleaning 8.5 (7 - 10)
Drying 7.5 (4-8)
118
-------
The amount of dust emitted during the various grain-handling operations
depends upon the type of grain being handled, the quality or grade of the
grain, the moisture content of the grain, the speed of the belt conveyors
used to transport the grain and the extent and efficiency of dust contamin-
ant systems (i.e., hoods, sheds, etc.) in use at an elevator. Many of these
factors have not been studied in sufficient detail to permit the delineation
of their relative importance to dust generation rates.
Part of the dust liberated during the handling of grain at elevators
gets into the grain during the harvesting operation. This dust "follows"
the grain to the country elevator and maybe to a terminal elevator or two
and then to the final processing point. Appendix A presents a brief dis-
cussion of some modifications to harvesting techniques that could reduce the
quantity of dust entering the grain during harvesting.
Grain dust emitted from these sources is composed of ~ 70% organic mate-
rial, about 17% free silicon dioxide, and specific materials in the dust in-
clude particles of grain kernels, spores of smuts and molds, insect debris,
pollens, herbicides, and field dust. Grain dust suspended in the air in
the interior of grain elevators consists mostly of highly dispersed particles
measuring < 5 um in diameter.
Dust emitted from grain and feed industry operations may cause irritation
of skin or eyes and respiratory ailments can be caused by inhalation of particu-
lates of <5 um in diameter.
At normal low ambient particulate concentrations (< 100 ug/nH) no evi-
dence exists for adverse effects to healthy people from grain and feed
emissions. However, people having preexisting respiratory disorders may be
affected or disabled by rapid increases above the seasonal mean concentration
of particulate grain dust. Appendix B presents a review of current knowledge
of the health effects of effluents from grain and feed industry operations.
It is a general practice in grain elevators to duct many of the individ-
ual dust sources to a common dust collector system. This is particularly
true of dust sources in the headhouse. Thus, aspiration systems serving
elevator legs, transfer points, bin vents, etc., may all be ducted to one
collector in one elevator and to two or more individual systems in another.
Because of the myriad possibilities for ducting, it is nearly impossible to
characterize a "typical" grain elevator from the standpoint of delineating
the exact number and types of air pollution sources.
Furthermore, many transfer points and bin vents do not emit dust ex-
ternally to the elevator, but rather emit dust to the interior of the eleva-
tor. When the latter situation exists, the dust presents a housekeeping,
working environment, or safety problem more than an air pollution problem.
119
-------
However, it should not be inferred that a building can be considered as a
suitable air pollution control system.
The many variations in elevator operating practices mean that only a
generalized picture of potential emission sources can be presented. A
specific elevator would require a survey of emission sources before its
air pollution potential could be accurately described. Specific grain
handling operations are discussed in the following sections. Each operation
is treated as an individual source with no consideration of common ducting
or external-internal venting options.
Grain Unloading - Elevators in the U.S. receive grain by truck, railroad
hopper car, railroad boxcar and barge. The two principal factors that con-
tribute to dust generation during bulk unloading are wind currents and
dust generated when a falling stream of grain strikes the receiving pit.
Falling or moving streams of grain inspirate a column of air moving in the
same direction. When this moving mass of grain strikes an immovable object,
the energy expended causes extreme air turbulence and a violent generation
of dust occurs. This undesirable situation occurs when trucks and railcars
are dumped into deep hoppers and also when railcars and the holds of ships
are loaded.
Grain unloading is an intermittent source of dust occurring only when
a truck or car is unloaded. It is a predominant source during the harvest
season and declines sharply or is nonexistent during other parts of the year.
Air pollution problems associated with each mode of grain unloading are dis-
cussed in the following sections.
Truck unloading - Trucks, except for the gondola (hopper) type, are gen-
erally unloaded by the use of some type of truck dumping platform. Gondola
trucks discharge through the bottom of the trailer. Elevators are often de-
signed with the truck unloading spot located in a drive-through tunnel.
These drive-through areas are sometimes equipped with a roll-down door on
one end, although, more commonly they are open at both ends so that the
trucks can enter and leave as rapidly as possible. This drive-through
access acts as a "wind-tunnel" so that the air is usually blowing through
this tunnel at speeds greater than the wind in the open areas away from the
elevator. The wind tunnel effect aggravates the dust problem and makes it
more difficult to contain and capture the dust.
The unloading pit at a grain elevator generally consists of a heavy
grate ~ 10 ft x 10 ft through which the grain passes as it falls into the
receiving hopper. This hopper will often be partially filled with grain
as the truck unloads because the conveyor beneath the pit does not carry
off the grain as fast as it enters.
120
-------
The dust-laden air, which is emitted by the truck unloading operation,
results from the displacement of air out of the hopper plus the aspiration
of air caused by the falling stream of grain. The dust itself is comprised
of field dirt and grain particles. The quantity of dust generated during un-
loading is largely a function of the type of grain and its moisture content;
soybeans and milo being considerably more dusty than corn or wheat.
Table 82 presents recently obtained data on emission rates from grain
receiving operations at grain elevators. All the data reported in Table 82
were obtained by various EPA contractors using EPA approved test methods for
particulate emissions (EPA Methods 1 and 5).
At Elevator A which is a transfer or subterminal elevator, emissions
were measured at the outlet of the control systems serving a truck dump pit
and the associated receiving belt and leg boot. Corn was received in loads
ranging from 13,000 Ib to 56,000 Ib each. Two receiving hoppers are enclosed
by a common shed with bifold doors at the entrance to each receiving bay.
Only one hopper was used during the testing program. The bifold doors were
closed behind each truck before it was dumped. The grate over the hopper is
about 14 ft x 16 ft with swinging baffles underneath to reduce the open area.
The receiving belt system aspirates dust from the point where the hopper dis-
charges grain onto the receiving belt and where the belt discharges into the
boot of the truck receiving leg.
Emissions from a truck dump pit were also measured at Elevator B.
Elevator B is a storage elevator associated with a soybean processing plant.
The truck dump grating is covered by a building; however, there are no doors
on either end. The hopper grate is baffled and 6,000 cfm of air is exhausted
from each side of the hopper. During the dumping of the trucks, visible emis-
sions were detectable in some instances from the lip of the truck bed as the
beans were discharged into the receiving hopper. These emissions varied from
0 to 10-20% opacity depending on the dirtiness of the grain, the type of
opening at the end of the truck where the beans were discharged, and the
velocity of the wind through the dump building.
Table 83 presents the results of emission measurements conducted for a
grain processing plant by an Ohio consulting firm. EPA approved test methods
for particulate emissions were used for the measurements. Tests were con-
ducted during periods of peak unloading of wheat in order to determine maxi-
mum emission rates.—' The truck unloading system is vented through Day Dual-
Clone Cyclones which pick up dust from below the dump grates. These cyclones
emitted a total of 2.6 Ib/hr while unloading an average of 508,000 Ib of grain
per hour. This relatively low emission rate from the cyclones was partly due
to the copious amounts of dust which escaped the dust collection system. This
dust was generated near the tail gate of the truck during dumping, and was
quickly blown away by the wind. Estimates of the quantity of this dust have
been made by grain industry personnel and vary from 0.8-2 Ib/ton of grain.v
121
-------
CO
s
O
M
S
PM
O
g
H
J
Q
s
3
Q
B
<
O
B
i-(
>
B
O
W
ftf
1
c2
o
g
Pn
H
H
"3
«
is
0
w
1/3
H
§
g
Pi
P
cn
a
a
CN
oo
4-1
01
s
a
3
W
O
U
(U
I— 1
g
4-1
c
(U
s
o
•1-t
3
D
W
m
o
4J
ai
c
1— 1
0)
4J
c
•H
4-1
c
E
Q.
•H
3
CT
Pd
U}
C3
O
•H
U)
cn
I
*
2
--
3
C
4-1
U
CO
VJ
M
^
o
i!
-~.
J3
i
M-l
O
CO
Vi
w
M
x:
ca
c
0
4J
13
01
?
to
re
(U
U]
0)
H
a
K
(U
d
o
Z
CM
0
°.
0
m
m
o
o
o
U
0
•s
J-]
o
»
rH
m
(N
d
3
^
to
T3
H
!
U
3
U
H
•<
t-4
O
o
o
vD
c-J
O
o
o
T3
a)
M
3
U
CO
QJ
S
t)
01
M
3
CO
nJ
,
ca
T3
P
M
g.
Jj
H
O
O
O
o
at
M
3
4J
M
1
<
VJ
0)
4J
r-l
4-1
a
u
CN
r--
2
at
u
OO
o
0
o
o
^o
0
o
o
o
CO
CO
So
•r-t
Q)
U
a)
TJ
c
122
-------
o
Pi
0
H
ta
rJ
w
C/1
&
O
H
H
o S
d o
P H
S U
<4 2
p2 ^-^
CD
a
o
oi
fe
C.O
O
M
w
C/3
§
•
CO
CO
OJ
,—1
,Q
H
CO
X~vl
V-i 3
O 43
O 43
CO .—i
O
X
CO
0
C
O x-
•H C
CO O
CO J->
•H \
W i— 1
^-
(-1
-^_
o
CO r-H
C "-*
0
r— 1
O
o
^
•
rH
CO
w ,^-M
•H "-W
i o
a co
i_j
w
^
rH
O
o
o
r— 1 --%,
CO U-(
CO O
O m
x-^
0) cO|
CO 4:
o -u --.
r-l Jd ,fl
C too i— *
(U
CD >
fi -i-l
O 4J
O M)
!^N 3
O fn
CM CO
CO
CM
r— 1
0
o
r— 1
^
O
CM
CO CO
1 1
O 0
r-H r-H
X X
r-~
C -H
O 4-1
r— 1 -H
CJ 00
>N 3
O h
CO <}•
CO
o
r— 1
X
00
-*
\Q
r— 1
O
m
•
0
m
CO
CM
^D
00
(3
•H
•0
CO
0
r-H
P
J-i
CO
[J
r— t
•H
CO
Pi
r-H
CO
4-J
0
H
0
X
r— 1
a
o
c
•r-l
CO
00
. 1?
CO -H
•H C
CO V-t
a- ^
4-1
r*-.
° o
^ X
r— 4
•O
-a cu
C u
co 3
Fu 5
0 >H
0 4-1
1^ 4J •
CO >*i
O r-H
4-1 !H C
rfl 0
•d ~-
OJ ,D CO
4-1 r— i CD
0 3
0) ON rH
rH o CO
r-l CM >
O
o oo H
T3 a.
>H Q,
CU r-4 CO
a. a)
•U 1
4-1 MH
• d) CO C
3d) O
43 "4-1 CD -r-4
~-~ 3 CO
43 O rH CO
rH -rH CO -H
43 £> S
03 (1)
vO O T3
CU "O
!3 T3 4J CJ
O IH CO 4-1
CO i — i co
TJ TJ rj g
cj C a -H
CO CO rH 4-1
CO 4-1 CO CO
M c/2 CJ W
123
-------
Due to the relatively clean wheat handled at this operation and based on ob-
servation of the unloading process, an emission factor for the amount of fugi-
tive dust escaping during unloading was selected which is somewhat lower than
the published value; namely, 0.4 Ib/ton. This is equivalent to ~ 100 Ib/hr
when unloading 508,000 lb/hr.l/
Emissions from cyclones and an experimental filter (CAM-VAC) used to
control emissions from other truck unloading stations are presented in
Table 84. Information was not provided on the configuration of the receiv-
ing pits at these elevators. Particulate sampling trains utilizing Hi-Vol
samplers were used to obtain the data shown in Table 84. At Elevator D, the
tests were conducted in accordance with procedures as outlined in ASME Power
Test Code 27. Two Rader Hi-Volume samplers were used to determine the simul-
taneous particulate loading to and from the cyclone. Extensions were added
to the cyclone exhaust to provide a sampling location /~ 10 diameters down-
stream from bends and two diameters from the duct discharge.^2.'
At Elevator E, a series of efficiency tests were conducted on an experi-
mental filter system (CAM-VAC) installed downstream from a cyclone unit used
to control dust emissions from the truck unloading station. The CAM-VAC fil-
ter is a high velocity fabric filter originally designed for use as a control
system for grain dryers and the tests conducted at Elevator E were the first
attempts to assess its capability in other dust control functions. Dirty air
enters the plenum chamber of the CAM-VAC unit and is exhausted through a fil-
ter media backed by a screen. The filter media form a half circle having a
perimeter of about 15 ft and is about 3 ft wide, which is equivalent to
45 ft2 of filter surface. If the unit operates with one fan at 9,000 cfm, the
air-to-cloth ratio would be 180 cfm/ft . The inside surface of the filter
media is cleaned by a vacuum head which moves up and down the semi-circle of
filter media. This vacuum head exhausts through a blower and cyclone.
The particulate sampling train used at Elevator E employed a Unico 500
Hi-Vol sampler. The nature of the test situation at the elevator did not
allow complete adherence to any formally recognized test procedure. Inasmuch
as actual dust loading could be maintained in the ducts only for a period of
1-2 min at a time, it was necessary to sample only at one traverse point
location for each test.2x'
At Elevator F, particulate emission tests were performed on the exhaust
gases of two CAM-VAC units in series. A 30-in. I.D. duct was extended to
within 5 ft of the ground for these tests. Duplicate tests were performed
with a sampling train using a Rader Hi-Volume sampler in accordance with ASME
Test Code 21.—^
Emission testing at Elevator G was conducted using procedures specified
by ASME Test Code 27 and a regular particulate sampling train.—'
124
-------
0 QJ - H
O O
o o
o o
I-- M QJ I
> T3 4J
I QJ S-|
•H M H3
QJ d O d
H r-1 U O
-------
Table 85 presents limited emission data for a cyclone system serving
a truck dump at another elevator.—' The data in Table 85 were provided by
one elevator that responded to the emissions inventory questionnaire. The
fan discharges to two identical parallel cyclones, but the emissions from
only one cyclone were tested. Test procedures specified by ASME Test Code
27 were used. No information was provided regarding the grains handled,
the configuration of the receiving pit, or the position of the dust pickup.
Table 86 summarizes the results of the emission testing reported in
Tables 82 to 85. Inspection of the data in Table 86 shows that the standard
fabric filter system is generally the most efficient control system. How-
ever, based on limited testing, a control system incorporating a cyclone
and CAM-VAC in series appears to provide performance equivalent to the stan-
dard fabric filter.
Hopper car unloading - A hopper car can be unloaded with minimal dust
generation if the material is allowed to form a cone around the receiving
grate (i.e., choke feed to the receiving pit). This situation will occur
when either the receiving pit or the conveying system serving the pit are
undersized in comparison to the rate at which material can be unloaded from
the hopper car. In such cases, dust is generated primarily during the
initial stage of unloading, prior to establishment of the choked-feed condi-
tions. Dust generated by wind currents can be minimized by the use of a
shed enclosed on two sides with a manual or motorized door on one end.
Boxcar unloading - There are three methods used for unloading grain
from boxcars and all present air pollution problems. The most common un-
loading method consists first of breaking the grain door inside the car
which produces a surge of grain (and dust) as the grain falls into the re-
ceiving hopper. After the initial surge of grain, the remaining grain is
scooped out of the car using power shovels a bobcat or some similar means.
This produces a surge of dust as each scoop is dumped out the car door into
the receiving pits.
The other common boxcar unloading method, used mainly by terminal
elevators, is a mechanical car dump which clamps the car to a movable sec-
tion of track and rotates and tilts the car to dump the grain out of the
car door into a receiving pit. This is a rapid method of unloading that
creates a large surge of dust in a manner which makes it very difficult to
efficiently capture the emissions.
Another boxcar unloading method, which is infrequently used, employs
a movable screw conveyor which is inserted into the car to draw the grain
out of the car door in a continuous stream.
126
-------
Q_i
p>j
S
Q
s^
u
§
H
O
H
H
CO
0
d
e
o
In
^J
H
O
O
H
C/}
m
oo
cu
1—4
W
H
4J
CU
[
4-1
3
O
i-i m co 1-1
O CN r-l
• m m m
o o o o
£E5 • • •
000
cu
G
o
1-1
o
o
4J
01
1-1 co m -> 4-1
1-1 O>
''C3 15
^-^ V— ^
M-I IH >4-i
O O CJ
CO CO CO
°~" — ^ ^
CO CO CO
G G G
•H -i-l 'H
CO cO CO
M r-l M
O O O
**0
vO O
• .
•, CU
CO rJ Pn CO
•I-l 'O °
M co
0) S S CX CO
4-1 E E 6 o
CO O CJ CU r-l
s
01
&0
1-1
CO
r-J
O
CO
•I-l
13
*J-t
O
r**i
4-1
•H
O
CO
0,
o
e and material transfer rate.
4J
CO
H
toO
C
••-1
13
CO
O
i— (
C
3
^
O
3
k
4J
n
r^>
4-1
•r-l
T3
o
g
§
0
CJ
c
o
toO
G
•H
rrj
C
cu
a,
OI
13
G
CO
4-1
•H
s"
3-
O
in
r-l
O
4-1
CN
S
O
1-1 •
^ too
T) G
cu co
•i-l ^
CO <»
> N
•^
4J CO
X S
G 3-
>H 0
G 'O
CO
M-l
CU
r^
4-1
4-1
CO
13
CU
4-1
O
OI
i— 1
O
o
1— 1
CO
•H
1-4
cu
4-1
CO
£3
U-J
O
cu
N
•H
CO
CU
i— I
0
•1-1
4J
CO
i — t
1
O
o
1 — 1
cu
4J
G
•H
i— i
CO
•H
^
CU
4-1
CO
g
CO
3
0
1-1
cu
•1-1
14-1
14_|
0
cu
CJ
G
CO
13
G
3
co
B
n *
0
O rJ
i-l 0)
cj co
r^)
O
0)
r~{
4.)
4J
CO
T)
0)
4-1
O
OI
i— 1
i-l
O
o
I— 1
CO
•i-l
j_j
CU
4J
CO,
g
14-1
O
CU
N
CO
cu
r-l
O
•H
4-1
CO
PM
f*t
o
1— 1
CO
•iH
l-l
OI
4J
CO
£3
4-1
CO
O
S
a
i— 1
CO
•H
r4
OI
4-1
rrt
g
13
CU
4-1
CO
J-l
OI
e
o
1— 1
bO
toO
CO
C
O
G
127
-------
trf
o
B
pi
H
5S
O
CO CO
H Pi
!S O
W H
&. ^
CO W
Si a
S <
jx^ p5
o o
H
oo H
CO <
M
a co
S3 H
H
rv i p_j
o
erf H
S 1 — I
a w
5 u
to W
Pi
•
*sO
OO
cu
,—1
^
CO
H
/— N
d
0
CJ JJ
cu --^
•U XI
CO i-l
^ N— ^
.— i
o
•
0
1
t— j
o
CO O
1 1 ^
CO 4-1 i-l O
3 cfl o
CO 4-1
<±t 60 d
o d o
•H O
CU T3
w) co m
d o o
CO i-J
Pi 4J
CU ON
i— 1 *^>
4J 4-1
3 O
O co
- — ^
5-1
M
o
o
o
1
CM
O
O
•
O
co
cu
r— 1
d
03
33
d
•H
CO
O
d
n)
CU
f,
O
CO
ft
d
o
u
13
O
^f]
4-J
cu
a
4-1
CO
CU
m
13
0
•3
CU
g
_*1
S
e
cu
4-1
CO
^
w
r-t
O
•IJ
d
o
o
^
>> >>
o cj
in
o
o
VO
co
o
o
CO
1-1
0
o
1
1— 1
0
o
d
o
CJ
^
CM
CU
TJ
O
£_}
4J
co
CU
H
W
CO
<
CO
4J
••-)
C!
3
CJ CO
-------
Table 83 presents data on emissions from cyclone dust collector systems
handling railcar unloading operations. EPA Method 5 procedures were used
to obtain the emission data. The enclosure around this operation was more
effective than that at the truck dump area at the same elevator and reduced
the amount of fugitive dust.—' The greatest emission source was Cyclone
No. 5 which vented the No. 1 elevator leg. This leg receives the unloaded
grain from a conveyor belt. Cyclone No. 5 emitted 28.3 Ib/hr from the un-
loading only. Cyclones Nos. 3 and 4 vented the car dump pit and emitted an
average of 3.7 and 3.5 Ib of dust per hour, respectively.—
Fugitive dust from railcar unloading was estimated using an emission
rate of 0.8 Ib/ton of grain. This is equivalent to 250 Ib of dust for the
623,000 Ib of grain unloaded in an hour. However, visual evaluation indi-
cated that the dust collection system picked up most of this, and it was
estimated that only 15 Ib/hr of dust escaped from the car unloading.3/
Barge and ship unloading - Dust emitted during barge and ship unload-
ing is relatively small in quantity in comparison with railroad car and
truck unloading. In most cases, the barges are unloaded by means of a re-
tractable bucket type elevator that is lowered into the hold of the barge.
There is some generation of dust in the hold as the grain is scooped out
and also at the top of the leg where the grain is discharged onto the trans-
fer belt. This latter source is more appropriately designated a transfer
point.
A system used for unloading grain received by barge at an elevator on
the Mississippi River was tested by an EPA contractor to determine dust
emissions. The results of the tests are presented in Table 87. The data
presented in Table 87 were obtained using EPA Method 5 procedures. At this
elevator, barges are unloaded with a bucket elevator consisting of two belts
of large buckets similar to those used in coal mining. The buckets move
slowly compared with the typical link belt system used for grain handling.
Approximately 25 tons of grain are removed from the barge per minute. The
dust collector for the link belt system aspirated dust from the grain hopper,
and from two conveyor belt transfer points. It appears that little dust was
generated in the barge by the bucket elevator. Most of the dust was gen-
erated when the grain emptied from the buckets into the hopper bin and at
the next conveyor belt transfer points. The total pickup efficiency of the
dust aspiration system appeared to be 7570. Visible emissions of fugitive
dust around the link belt were about 307o opaque.
Grain Loading - The loadout of grain from elevators into railcar, truck,
barge or ship is another important source of particulate emissions and is
difficult to control. Gravity forces are usually used to load grain with
the grain being drawn from bins above the loading station or from the
scale in the headhouse. The main causes of dust emission when loading bulk
129
-------
ft-l OJ
0) > u-i
i T3 0)
-------
grain by gravity into trucks or railcars is the wind blowing through the
loading sheds and dust generated when the falling stream of grain strikes
the truck or railcar hopper. The grain leaving the loading spout is often
traveling at relatively high velocity and generates a considerable amount
of dust as the grain is deposited in the car or truck.
Most country elevators do not have any dust collection system installed
on these sources and in many cases, the loading stations are not covered
or enclosed except for the drive-through tunnel. The loading operations in
terminal elevators are often enclosed for weather protection, but few have
attempted to collect the emissions that occur during loading*
Dust emitted during loading of barges and ships can be quite significant
but very difficult to control. The openings for the holds in these vessels
are large, making it very hard to effectively capture the emissions. For
this reason, most elevators have not as yet attempted to control this particu-
lar source.
Grain Dryers - When the grain received at the elevator has a moisture content
higher than that at which grain can be safely stored, then it must be dried
within a few days after receipt. Although many grains may require drying
under certain conditions, corn is the grain that usually necessitates the use
of the dryers. When corn is received, it may contain 207=, moisture or more,
and must be dried to 13-14% moisture to be suitable for storage.
Grain dryers present a difficult problem for air pollution control be-
cause of the large volumes of air exhausted from the dryer, the large cross-
sectional area of the exhaust, the low specific gravity of the emitted dust,
and the high moisture content of the exhaust stream. The particles emitted
from the dryers, although relatively large, are very light and difficult to
collect. "Beeswing," a light flaky material, that breaks off from the corn
kernel during drying arid handling, is the troublesome particulate emission.
Effluent from a corn dryer may consist of 25% beeswing, which has a specific
gravity of about 0.70-1.2.
The rate of emission of particulates from grain dryers is primarily de-
pendent upon the type of grain, the dustiness of the grain, and the dryer
configuration (rack or column type). Field run soybeans usually create the
greatest visible emission. However, during corn drying the characteristic
"beeswing" is emitted along with normal grain dust. Essentially, all bee-
swing emissions are over 50 um in diameter and the mass mean diameter is
probably in the region of 150 um. In addition to the beeswings, the dust
discharge from grain dryers consists of hulls, cracked grain, weed seeds,
and field dust. Approximately 95% of the grain dust is larger than 50 Urn.
131
-------
Rack or column type dryers are usually employed to dry grain at eleva-
tors. Figure 7 presents schematic diagrams of both types of units. A new
type of column dryer, the recirculating unit, has recently been introduced
to the market. In the recirculating unit, a portion of the air used to dry
the grain is continuously recycled. Approximate air flow requirements for
the dryers are:
Column dryer - 100 acfm/bu/hr
Rack dryer - 70 acfm/bu/hr
Recirculating dryer (column) - 30 acfm/bu/hr
Column dryers have a lower emission rate than rack dryers since some
of the dust is trapped by the column of grain. In order to control the dust
which is emitted from the columns, it is necessary to build an enclosure.
This enclosure also serves as a relatively inefficient settling chamber. In
rack dryers, the emission rate is higher since the turning motion of the grain
generates more beeswings and the design facilitates dust escape. The rack
dryer is exhausted only from one or two points and is thus better suited for
control device installation.
A quantitative assessment of emissions from grain dryers is difficult
because of the absence of an acceptable test method. Available data on
emissions from grain dryers are discussed in the following paragraphs. Be-
cause of the lack of an acceptable test method, the data available should
be considered as indicative of probable emission levels and not absolute
numbers.
The results of emission tests conducted by an EPA sampling team on a
grain dryer in Colorado are summarized in Table 88. The equipment tested
at the elevator was an Aeroglide rack dryer (Model 2010 CGLH) equipped
with a Wiedenmann Screen Kleen control system. The Wiedenmann unit consists
of a 14-ft diameter, metal, 34 mesh screen and its supporting framework.
Chaff and beeswings collected by the Screen Kleen are vacuumed off the
screen and recollected by a cyclone. Material that settles inside the
screened enclosure is occasionally shoveled out onto the ground.
An Aeroglide Model 2010 CGLH rack dryer is designed to dry 1,000 bu/hr
on a drying and cooling mode. The dryer was operated at 2,750 bu/hr during
the tests. The 14-ft diameter exit was traversed in two directions 90 degrees
apart and 12 points were sampled 5 min each. A total of 3-1 hr tests were run.
The tests were performed with a 25.5 cfm hi-vol sampling train. Based on the
average emission rate of 98.3 Ib/hr and the drying rate of 2,750 bu/hr, a con-
trolled emission factor of 1.3 Ib/ton was calculated for this dryer.
132
-------
MOISTURE
LADEN
AIR
OUT
(a) Rack Dryer
Grain
Receiving
Air
Sea
Dryer Section
Cooler
Section
.
•*—
•*—
•^Mi
••«
•>llll
.«_.
•^B-
•<—
--^•«
X,
p
•f
•s
••
••
•r
i"
Ui
F!-
X
w.
Garner
"** >"*>
^^v -^™1
— *. ^—i
-1
n
D~
fl>
* -T ^—
M. J_ to
1 1
1 1
1 1
1 1
1 1
X
rt
M
*F
bpt
m
^
•>
**
•x^-
— •»-
»^.
— •>•
— •»•
MB».
-^
—»-
—•>
Figure 7,
\
Variable Speed Discharge
(b) Column Dryer
Schematic diagram of column and rack grain dryers.
133
-------
@
><
& ^~
Q CTil
CO
W z
u 0
23
^
W
s §
3S
O O
Crf W
W i ,
*
H ^
C/l £Q
W
M Q
S M
0 >J
rl
0
• Pi
oo H
00 13
O
cu o
1— 1
J2
(0
H
-£
w C
0) 3
H OJ
i— i
r-l
•
00
^
s^
1— 1
•
o
P^.
v
CO
C7>
m
co
r-l
n
V0
^O
o
o
T— 1
oo
o
o
o
n
CM
m
0
in
P^.
A
CM
^
O
i— 1
(U
a
o
• u
s
CM
CO CO
• •
o oo
O O"v
1-1
m
tr> 0
00 O
i— I
O O
0 O
r-l O
^c
0
m
A
CM
»
O
r-l
(U
C
•d- M
O
• O
CO
•
isture
g^2
m
r-l
O
4J
CU
M
3
4-1
CO
•rl
o
^
1— 1
e
0
IH
13
0)
•rl
V4
T3
a
o
CJ
"^^.
cd
134
-------
Table 89 summarizes emission tests conducted by an EPA contractor and
an EPA sampling team on a Hess rack dryer controlled with a DAY-VAC dust
filter, Model 2-6, equipped with 12 (100 mesh) polyester screens. The DAY-
VAC unit consists of twelve, 2 ft by 2 ft 100-mesh, polyester screens which
filter particles from the air passing through it. A vacuum head travels up
and down the face of the screen to suck off dust collected there. New
screens were installed about 3 weeks prior to the emission tests.
Particulate emission measurements were performed using the EPA Method 5
sampling train and a 25.5 cfm hi-vol sampling system. The hi-vol train and
one EPA Method 5 train were stationary and side by side. One EPA Method 5
train traversed the exit of the filter face.
As shown in Table 89, controlled emission factors for the series of
tests ranged from 0.1 to 0.38 Ib/ton of material dried.
The State of Illinois Institute for Environmental Quality has conducted
a series of tests of particulate emissions from grain dryers using the UOP
sampling train and the Joy Manufacturing Company--EPA sampling train.-t±/
Table 90 summarizes the results of the testing program.
At Elevator A, the Aeroglide rack dryer operated continuously during
the testing, drying corn, at the rate of 1,033 bu/hr. Tests 1 and 2 were
performed using UOP sampling units equipped with cloth fabric filter bags
to catch the small particles and jars prior to the filter bags to catch
the beeswings and larger particles. Test 3 was conducted with the Joy
Manufacturing Company--EPA unit which was equipped with a heated filter
assembly and an itnpinger train.
At Elevator B, an Aeroglide rack dryer equipped with a Wiedenmann
Screen Kleen unit (50 mesh screen) was tested. The dryer operated smoothly
during the testing periods except for one malfunction that required a shut-
down during one test period. Corn was cleaned with two Scalperators in
parallel and dried at the rate of 4,000 bu/hr. Tests 1 and 2 were performed
with the UOP sampling train. The first test had to be aborted half way
through due to a malfunction of the dryer equipment. The second test went
very smoothly. Tests 3 and 4 were performed using a Joy Manufacturing
Company--EPA sampling unit. Test No. 2 is believed to be the most reliable
test giving an accurate indication of the emission rate. Test No. 1 was
A 1 /
only a half of a complete traverse and the results had to be extrapolated.—
Two things are evident from the data in Table 90. First the Joy-EPA
sampling unit consistently gives lower results than the UOP sampling units.
Second, compared on the number of tons or bushels dryed per hour, the 50
mesh screen dryer installation has approximately 78% fewer emissions than
the uncontrolled dryer installation.
135
-------
•H HI <0
D
O
0*
m
00
o
0)
O
o
00
fO
01
CO
tn 1
CO r-l
OJ "O
6 C
CO (0
to
ffl
•o
1
•-1
ca
W
U
u
ca
MH
c:
OJ
0)
M
en
g
ffl
CO
CO
0
o
0
01
o
o
CO
01
m
§•§
ca ca
i
01
•a
c
(6
1
01
CO
a)
aj
jj
«
OJ
£
-H
-rj
0
o
o
-J-
U~l
LH
OJ
Ol
o
CO
i-H
C">
CQ
§•§
(0 CO
PQ
tJ
C
ca
i
CO
CQ
0)
E
CO
CO
u
ro
c
OJ
)-*
CO
CO
0
£
c
CO
u
4-J
in
1
0>
2
P-
U
O
•H
4J
CO
<
,
CO
Ol
*-*
^0!
C
CO
4-1
^
a>
S
td
M
C
•^t
™
01
ra
H
r
rq
,
CO
CM
r-l
^1
.
>!
Vj
d
o
4-1
CO
4-1
01
0>
01
0)
o
ffi
"ej
»
O
Vi
T3
•r-l
T)
co
CO
3
C
Li
0
u
c
CO
co
u
w
O)
H
•H
01
4-1
TO
CO
O
00
o
0>
•a
ca
C
O
o
pa
T^l
d
CO
0)
H
C
M
^
QJ
d
CO
• H
g
CO
0
fr-S
CTi
•vf*
B
o
U-l
•o
OJ
t-i
"0
3
a
o
o
en
-a
c
m
4J
TJ
4J
OJ
4-1
CD
Si
Jj
bO
•o
ai
o
o-
10
cd
1.
U-l
0
o
4-1
'u
0
o)
o
4J
cO
O
4J
136
-------
t!
o
V
137
-------
Evaluating the test results from both locations, it is evident that the
Joy-EPA sampling train consistently gives lower results than the UOP train.
A number of factors may contribute to this. The cross-sectional area of the
nozzle and tube is constant from the nozzle through the tube to the cyclonic
separating device in the UOP sampler, while in the Joy-EPA sampler, the
nozzle area does not equal the cross sectional area of the probe. This
means that there will be a velocity reduction in the probe of the Joy-EPA
sampler and particulate matter may settle out to some degree. This is im-
portant because the Joy-EPA sampler probe is quite long and difficult to
clean thoroughly.—'
Any loss of particulate catch is magnified by the fact that the Joy-EPA
sampler is a low volume unit. It is designed to pull only about 1 cfm while
the UOP samplers can pull much more than this, up to 5 to 10 cfm. The large
sample volume capabilities of the UOP samplers reduce the chance and magni-
tude of errors that could be encountered with the small sample volumes that
the Joy-EPA sampler is designed to handle. More sample volume means more
particulates will be caught so that the loss of some particulate catch will
produce an error of a much smaller magnitude than that produced when a
smaller volume is sampled. For all these reasons, it is likely that the
UOP sampler is better suited to the testing of grain dryers where large air
flows are encountered and that the UOP sampler test results are more represen-
tative of the actual emission rates of the grain dryers tested.—'
Test results shown in Table 91, provided by the Aeroglide Corporation,
indicate an uncontrolled emission rate of «-> 130 Ib/hr or 2.3 Ib/ton dried
for a 2,000 bu/hr corn dryer.—' Details of the test procedure were not re-
ported.
Table 92 summarizes results of determinations of emissions from a
Zimmerman Continuous Flow Dryer, Model 8AP-1200, being used to dry corn.
An emission rate of about 6.2 Ib/hr was determined from these tests. The
results of two particulate emission tests conducted on the exhaust gases
of a Mathews Company Model 900 grain dryer (column dryer) are presented in
Table 93. Corn was the grain being processed at the time of the tests. A
Rader Hi-Volume Sampler was used to conduct the tests reported in both
Tables 92 and 93. Sampling procedures of the ASME Power Test Code 27-1957
were followed during the tests.—'
Table 94 presents results of emission tests on a Berico Industries
Turn-Flo Dryer.— Soybeans were being dried during the time the emission
tests were conducted. Details of the test procedures and characteristics
of the grain (i.e., percent foreign matter, moisture) were not available.
138
-------
Table 91.^ DUST EMISSION TEST ON 2,000 BU/HR AEROGLIDE RACK GRAIN DRYER
Screen House
Conditions
°F
°F
Gas temperature (dry)
Gas temperature (wet)
Gas density at conditions (lb/ft3)
Gas velocity (ft/min)
Gas volume (cfm)
O
Grain loading at actual conditions (grains/ft )
Grain loading at 70°F (grains/ft3)
Dust loading (lb/1,000 Ib gas)
Dust emission (Ib/min)
Dust emission (Ib/hr)
92
61
0.07184
2,910
81,481
0.1896
0.1975
0.3771
2.207
132.5
Table 92. SUMMARY OF RESULTS OF EMISSION TESTS ON ZIMMERMAN CONTINUOUS FLOW
GRAIN DRYER
Test 1
Test 2
I. Corn Data
Moisture content before drying (% by weight) 23.1
Foreign matter before drying (7a by weight) 1.2
Grain temperature before drying, °F 50
Moisture content after drying (70 by weight) 13.6
Foreign matter after drying (% by weight) 1.7
Grain temperature after drying, °F 44-46
Through put in dryer, Ib/hr 54,200
Through put in dryer, bu/hr 968
II. Emissions at Standard Conditions (32°F, 29.92 in Hg)
*j
Grain loading, grains/ft
Emission rate, Ib/min
Emission rate, Ib/hr
Emission rate, Ib/ton
Beeswing collected, grains/ft3
Beeswing collected, Ib/min
Beeswing collected, Ib/hr
0.0124
0.0875
5.25
0.19
0.00003
0.00021
0.01
24.0
1.5
38
18.8
Not available
46
61,500
1,098
0.0168
0.1188
7.12
0.23
0.000027
0.00019
0.01
139
-------
Table 93. SUMMARY OF RESULTS OF EMISSION TESTS ON MATHEWS COMPANY MODEL
900 GRAIN DRYER-/
Test 1 Test 2
Exhaust gas volume, scfm 46,904 46,890
Particulate output^/ 0.00636 0.00623
concentration, grains/scf
Mass emission rate, Ib/hr 2.56 2.50
Process weight, bu/hr 400 400
Pounds/Hour-/ 22,400 22,400
Emission factor, Ib/bu 0.0064 0.0063
Emission factor, Ib/ton 0.23 0.23
Corn data: At the time of the tests, the dryer was processing the
following corn.
Inlet Corn Outlet Corn
Percent moisture 21 15
Percent foreign matter 1 3
a/ Standard conditions of 70°F and 29.92 in Hg.
b/ 56 Ib/bu.
Table 94. SUMMARY OF RESULTS OF EMISSION TESTS ON BERICO INDUSTRIES
TURN-FLO DRYER-/
I. Dryer Data
Grain processed: Soybeans
Dryer capacity: 2,000 bu/hr (187,600 cfm)
Control equipment: 2 Weidemann Screen Kleen Units
(93,800 cfm per unit)
II. Test Results
Collection duration: 210 min
Total mass collected: 2.2 g
Sampling rate: 41 cfm
Dust emitted per screen: (2.2) (93,800) = 23>9?
(210) (41)
Total dust emitted from dryer: (2) (23.97) = 47.94
1 IK , __ lb
tir
= 0.11-^
tor
140
Emission rate: (47.94 (60 ) (— -j) = 6-33
-------
A summary of available data on emission tests on grain dryers is pre-
sented in Table 95. Examination of the data in Table 95 indicates that the
emission rates vary with dryer type, grain dried, and sampling techniques
utilized in the testing. Uncontrolled emission rates range from 0.2 to 3.8
Ib/ton of grain dried, while controlled emission rates vary from 0.04 to
0.84 Ib/ton of grain dried. Because of the significant dependence of the
emission rates on the sampling procedures, the data in Table 95 should only
be considered as indicative of the general level of emissions from grain
dryers.
Grain Cleaning - Grain cleaners are used in many grain elevators especially
at terminal facilities. Equipment used to clean grain varies from simple
screening devices to aspiration type cleaners. The simple screening devices
remove large sticks, rocks, tools, and other trash, while the aspirators
remove chaff and other light impurities.
Emission test data from initial grain cleaning operations at storage
elevators at two flour mills are presented in Tables 96 and 97.~~ Wheat
is the grain being cleaned in both instances. Since the wheat received at
flour mills generally has come from a terminal elevator where the grain
may have been cleaned also, the data in Tables 96 and 97 probably represent
the lower ranges of dust emission rates that would be expected at a grain
elevator where the grain undergoes its first cleaning.
At the processing facility represented in Table 96, the three aspirator
cleaners were served by cyclones and processed a total of 10,000 bu/hr in
approximately equal portions during the test period. Emissions ranged from
0.04 to 0.11 Ib/ton. No reason is apparent for this difference in supposedly
identical processes.—' The unequal air flows in the three vent systems in-
dicate that the damper settings were not the same, and this in turn could
affect the amount of dust picked up. A cyclone also controlled emissions
from the scalper at this mill. This cyclone emitted 4.8 Ib/hr or 0.008 Ib/ton
when processing about 20,000 bu/hr.—'
At the second elevator, a cyclone is also used to control emissions from
a grain cleaner. As shown in Table 97, emissions from the cyclone were
measured as 1.46 Ib/hr or 0.185 Ib/ton of grain handled by the Carter cleaner.—'
Garner and Scale Bins - Both country elevators and terminal elevators are
usually equipped with garner and scale bins for weighing of grain. A
country elevator may have only one garner bin and scale bin. However, a
terminal elevator might have as many as four separate scale and garner bin
systems, each with a capacity on the order of 1,200 to 2,500 bu to process
35,000 to 75,000 bu/hr.
141
-------
S3
d o
c - o
O & ov]
y o ^
142
-------
"^
23
55
M
1 1
u
£3
M
os
O
S
o
etf
Pn
CO
la
o
M
CO
w
vD
0)
i~H
03
u
o
4-1
U
to
d
0
•rl
CO
CO
•H
^
W
CO
d
o
•r4
CO
CO
•rl
e
w
s~
o.
1— 1
fc
CO
CO
O
CO
CO 4J
Q) j-
CJ 60
O -rl
I-l 0)
PM Cs
CO
1
O
3
JZ
•^^
JD
i-l
X
vO
00
•
r-l
d
o
4J
^Q
r-l
£
&
r-l
O-J
vD
0
o
CN
vO
MH
CJ
CO
•• — ,
CO
d
•H
tfl
Jj
o
1— 1
00
0
o
£1
p
'ft
CJ
CO
o
o
*,
CTi
"-^
J-l
^
rd
1-1
0
o
o
o
o
CN
CO
1
o
l 1
X
^o
CN
1— 1
c\i
- S-i
rd CJ tfl
i-l -rl
43 CO
O 3 CD
vO O d
O
C T3 i"™i
O M O
T3 T3 CJ
cu d
CO CO r-l
Cfl 4-1 r-l
PO CO <
143
-------
Table 97. EMISSIONS FROM GRAIN CLEANING OPERATIONS-'
&/
Item
a/
Grain cleaning rate (bu/hr)—
Process weight rate (lb/hr)—'
Source gas volume (scfm)
Duct static pressure (in 1^0)
At Cyclone
At Fan
Fan speed (rpm)
Dust concentration (gr/scf)
Dust emission rate (lb/hr)
Emission factor (Ib/ton)
Inlet Exhaust
500 500
30,000 30,000
3,330 3,330
+ 1.0 - 16.0
- 16.0 + 0.2
1,200 1,200
0.098 0.051
2.78 1.46s-
0.185 0.098
a/ Carter cleaner handling 500 bu/hr, wheat.
t>/ Computed as the product of the cleaning rate and the average bulk
density of No. 1 heavy dark northern spring wheat (60 Ib/bu).
c/ Cyclone operating at 3,330 cfm which is 39% of designed capacity of
8,500 cfm. Unusually high pressure drop across cyclone (17.0 in t^O)
indicates a restriction or improperly set damper between the pressure
taps.
144
-------
Dust is emitted from both the scale bin and garner bin whenever grain
is admitted. The incoming stream of grain displaces air from the bin,
and the displaced air entrains dust. In some cases, the bins are completely
open at the top while others are enclosed, but vented to the surroundings.
Table 98 presents recently obtained emission data for a scale system
at a terminal elevator. The data were obtained by an EPA contractor using
EPA Method 5 procedures. The scale system aspirates dust from the conveyor
belt discharge point, the first garner bin, the scale, the second garner bin,
and the head of the conveyor to the elevator leg.
Elevator Legs - The "leg" in a grain storage facility is commonly a bucket
elevator that receives the grain and elevates it to the top of the headhouse,
where it is discharged to a distributor system. Many country elevators have
only one leg, which may range in size from 2,500 bu/hr up to 10,000 bu/hr.
Legs in a terminal elevator may each handle 30,000 bu/hr or more.
The top of the legs is generally vented or aspirated in order to re-
lieve the air pressure and remove dust created by the motion of the buckets
and the grain flow. It is also done in some cases as part of insurance re-
quirements. A variety of techniques is used to vent elevator legs. Many
are aspirated to cyclones and some are vented directly to the atmosphere.
Some are aspirated at both the top and the bottom. Some have installed
ducting from the top to the bottom in order to equalize the pressure, some-
times including a small blower to serve this purpose. Others are operated
completely closed without venting.
The leg can be an uncontrolled source of dust emissions if it is vented
to atmosphere at the top of the leg, but more often the top of the leg is
aspirated with a fan discharging to a cyclone. Table 99 presents results
of emissions tests on a cyclone used to control emissions from an elevator
leg. A particulate sampling train using two Rader Hi-Volume Samplers were
used to determine simultaneous particulate loading to and from the cyclone.
Extensions were added to the cyclone exhaust to provide a sampling location
approximately 10 diameters downstream from bends and two diameters from the
duct discharge. Tests were conducted in accordance with ASME Power Test
Code 27. The grain handling rate was not reported.
Table 100 presents particle size distribution data for the cyclone inlet
tests. The particle size distribution was obtained by 15 min Rotap screening
and by microscopic methods (ASTM E-20). Inasmuch as the +200 and +325 Rotap
fractions showed serious screen blinding, they were lightly disturbed with a
camels hair brush to disperse agglomerates. The microscopic examination of
the 325-mesh fraction showed very few agglomerates and no detectable milling
of the particulate.
145
-------
g
w
E-i
CO
^1
CO
w
^
o
CO
erf
O
fe
CO
w
H
^3
erf
E5
o
M
CO
CO
M
§
p
w
g
CO
CM
s
•
oo
c^
0)
o
CO
H
cu
1-1
45
•H
CO
•I-l
£>
T3
CU
JJ
CO
0)
H
JJ 4J
^J £j
QJ
60 £
C3 p
-0 3
cfl D"
0 W
^J
M-l
4J 0
CO
3 JJ
Q CU
r-l
JJ
3
O
CU
JJ
CO
erf
CO
CO
cu
U
o
J_j
P-I
a
•r\
CO
CS
JJ
•H
C3
O
•H
CO
CO
•r-l
a
c3
U
CO
a.
o
g-4J
o
r-l
X-«J
£3
o
JJ
^^
43
r-l
x—-
^O
CO
l
O K
O
O H
0
U
«J
T
8
W
[55
O
m
0
CO
•^^
}_l
M
J
CN U
CM >H
CM O
O
• i^"*
O PQ
Q
W
^-^
^
rc*
"^.^
CO
CI
o
4J
s_>
H^
. I
0 O
r^ erf
O H
A ^7
8
O
U
•* hJ
C3
jj co erf
w cu m o
PH . "-) H
cu
JJ
CO
cu
H
JJ
C
cu
g
a
•H
3
5
re o <
£2 CU CX ^
bO co . W
CO r-l Vl 43 J
n m CU W
T3 > 0
, cu
cu
- '
5
CO
H
bO
I C
I -H bO
B r-l C
CU T3 -H
cu
U
3
O
CO
jj a 43
co co bO
>, 43 -i-l
CO 0)
C &
CU -H
r-l Cfl Tt
cfl Vi C
0 bO O)
CO
/r^
J^
43
n
r-l
to r^ ^^
r-H r-l CM
• • •
in o o o
CM
^^
CO
0
O
CO
CO
•H
-S
HH y-N
M-t
U
CO
•^x^.
J^l
w
vD r^ co
r-l r-H CN
00 O O O
0 9 • •
CO O O O
CO
^
O x^^
r^| (^
U
CO CO
« ^
O
oo P** Is** r**-
-------
Table 100. PARTICLE SIZE DISTRIBUTION FOR LEG CYCLONE INLET TEST
US Sieve
Mesh
6
7
16
20
40
60
100
170
200
325
Microscopic
Microscopic
Microscopic
Microscopic
(see Table 99)
Size Opening
(microns)
+3,327
+2,830
+1,190
+ 840
+ 420
+ 250
+ 149
+ 88
+ 74
+ 44
+ 20
+ 10
+ 5
+ 1
Cumulative Weight
0.5
0.9
7.6
12.3
21.0
26.5
32.7
44.7
48.7
68.0
91.0
99.1
99.9
99. 9-/
&J Greater than.
147
-------
The -325 mesh fraction was dispersed in benzene and filtered on a
0.45 u milliporepad. The pads were cleared with immersion oil. Multiple
counts were made at 800X using a Unitron MPH phase contrast microscope
under light field conditions. The particle frequency counts were con-
verted to mass percentages by assuming spherical particles of homogeneous
density.
Transfer Points - When grain is handled, the kernels scrape and strike
against each other and the conveying medium. This action tends to rub
off small particles of chaff and to fragment some kernels. In this manner,
dust is continuously generated and the grain is never absolutely clean.
Belt conveyors have less rubbing friction than either screw or drag con-
veyors, and generate less dust. Dust emissions usually occur at belt
transfer points as materials fall onto or away from a belt. Belt speed
has a strong effect on dust generation at transfer points. Examples of
transfer points are the discharge from one belt conveyor onto another belt
conveyor or the discharge from a leg onto a belt conveyor or the discharge
from a bin onto a tunnel belt. If these transfer points are open to the
atmosphere, an air pollution problem may result.
Every process in the elevator involves turning (or moving) the grain.
Turning includes the operations of belt conveying, elevator transfer, turn-
head operation, and bin dumping. Most of these same conveyors and elevators
are also used during unloading operations and at times a control system may
be serving multiple operations.
Measured emission data for grain handling operations at an elevator
serving a flour mill are presented in Table 101. In Table 101, emissions
from cyclone systems used at one storage elevator to control dust emissions
from various equipment used to transfer grain are summarized.—' All the
cyclones are Day Dual-Clone units. One cyclone vents the upper north and
south conveyor belts and the storage tanks. This cyclone emitted 3.5 Ib/hr
or 5.85 x 10~3 Ib/ton of grain handled. Another vents all the turnheads
in addition to the dryer feed belt and the upper north belt. The emissions
O
from this cyclone amounted to 17.8 Ib/hr or 29.7 x 10"J Ib/ton of grain
handled. Two cyclones are used to vent the lower belts and the elevator
o
legs of the grain turning system. These units emitted 4.85 x 10~J and
4 x 10 Ib/ton of grain handled, respectively.—'
Table 102 presents dust emission data for the control system serving
the tunnel belt aspiration system at a terminal elevator. The emission
data were obtained by an EPA contractor using EPA Method 5 testing proce-
dures. Except for Test No. 4 no significant differences were noted in
the individual tests. Reasons for the significantly higher emissions rates
observed in Test No. 4 were not discussed by the EPA contractor who per-
formed the testing.
148
-------
CO
I
VH
^
W
53
i
CJ
PQ
8
[j
o
Pi
8
CO
53
O
M
H
M
fa*
PH
O
O
53
g
g
H
53
H
5
^
o
r-l
X
m
en
O
en
^^^
c
o
4J
^Q
d
i
o
r-l
K
m
oo
m
•*^
Ho
d
c
a
.,J
0
W
M
^
rH
m
m
CA
-~^
01
r-l
m
o
o
g ^
^ A"I
fa p
iF
to u
tO rn
O -C*
00
o
A
f^.
' s~*
~eo|
j_i
CO J3
CO 4J \
CU ,*"i ^
CJ 60 r-l
O -rl
I-l OJ 0
PH S 0
O
r-l
^
4-1
CO
CU
J"*
Jj
• «\
O
o
CM
n
r-l
^4
CU
ft
P-l
3
cu
U
M
3
O
CO
d
o
•rl
CO
CO
•H
J3
W
§ CO
4J
CO
60 4J
d r-l CO
•rl CU U
•u ,n -H
d rQ
cu j-i
p> o cu
>, 00
CU CU CO
d > r-l
o d o
r-l O 4J
U U CO
u1
<*>
i
0
r— 1
X
oo
r^
en
1
o
r-l
X
I--
Oi
00
•
^ — I
00
en
o
o
o
m
m
4->
CO
cu
f~i
j5
• n
O
o
CM
n
r-l
T3
cu
CU )-l
<4-l CU
r-l ft
r-l h ft
CO CU 3
^»
60 r-l CU 4J
C T3 d r-l
•rt O CU
4-1 •> ,0
d CO T3
CU T3 d r-*
> CO CO O
CU >,
0) 43 « CU
d d 4J >
O r-l «-l d
rH 3
CO
CO 4J
CU r-l
d cu
0 rO
' U M
>s <1>
U S
0
O rH
rH
en
1
o
M
CM
rH
O
en
1
o
1— 1
4r
CM
CM
en
O
CD
o
in
oo
CM
•
o
cu
d
o
u
o
4-J
CO
n i ^^
O CO
CO 60
60 d
0) -rl
r-H B
rW 3
O 4J
4J
> -H
0) CO
r-l rH
CU 60
CO
•rl
CO
ft
^
h^-
rH
T)
d
tO
fa
O
O •
r>- co
4-)
O CO
4-> CU
4-1
CU rH
4-1 rH
O CO
CU
rH d
rH -rl
O
O TJ
CU
cu co
4-1 3
3
d d
•H «rH
0 cfl
rH
r-l 4-1
CU
ft 60
4J -H
• CU rH
3 OJ ft
J3 O tO
rH -rl
^D in
0 3
vO O T3
O
O M 4-1
CO CU
""O 'O S
cu d
en « <;
CO 4-1 PH
pq en w
«| rO| 0|
149
-------
OJ
o
6
Eq
j •]
<3
^
r-l
W
H
G Cl
3 O
H 0
in
i
o
r-H
X
00
vD
CO
r^
i
o
r-H
O
r-H
CO
^J-
rH
•
O
o
o
0
CO
i-H
*
O
rH
•H
B
[J
0
rH 5-5
rH CO
, -rl
•H en EH <
B
cu
CO
^
CO
in
t
0
r— 1
in
^
rH
r^
t
O
rH
X
in
rH
^
o\
in
0
•
O
o
o
m
A
(T)
1— t
n
0
r—t
•rl
B
S
0
rH CO
<1) r-H ,
>^ 4J
O D. CO
•rl 0
U IH O
A CX V4
rl (>> J>!
rj o S
4J 0. G- ^
O "^O
rH 4J O
O •• r-l > P 'rl g P
- 3 & E 3
CM g 4J 4J
PM B T3 B-i 01
. -rl p CM -H
O er-5 O co • O
B3 "0 6 W o E3
-------
Figure 8 presents particle distribution data for dust entering the dust
control unit for the tunnel belt aspiration system discussed in the preceding
paragraph. The Brink Model B cascade impactor with a back up filter was used
to obtain these data.
Table 103 presents dust emission data for a portion of the grain handling
equipment at another elevator.— The testing procedures used to obtain the
data in Table 103 were not reported.
Another series of emission tests on cyclones controlling dust emissions
in various parts of an elevator is presented in Table 104. The tests were
conducted in accordance with procedures of ASME Power Test Code 27. Particu-
late sampling trains using Rader Hi-Volume sampling systems were used in the
tests. Extensions were added to the cyclone exhausts to provide a sampling
location approximately 10 diameters from obstructions and bends. At this
elevator, legs and all conveyor transfer points and drop points are equipped
with suction hoods ducted to cyclones. One collection system and blower
serves the basement area while another collection system and blower serves
the headhouse area. The railcar loading station used a garner bin which
was filled by means of a bridge conveyor from the elevator proper. This
bridge conveyor was covered and was equipped at the head end with a suction
fan discharging to a cyclone. Grain handling rates were not reported by the
organization which conducted the tests summarized in Table 104. As a re-
sult, emission rates in terms of pounds per bushel or pounds per ton of
grain handled could not be determined.
Bin Vents - Bin vents are small screen covered openings located at the top
of the storage bins or silos, and they are used to vent air from the bins
as the grain enters the bin. The grain flow into a bin induces a flow of
air with the grain and the grain also displaces air out of the bin. The
air pressure that would be created by these mechanisms is relieved through
the bin vents. The flow of grain into the bin generates dust which may be
carried out with the flow of air through the bin vents. The quantity of dust
released through the vents increases as the level of the grain in the bin
increases.
Bin vents are common to both country and terminal elevators, although
the quantity of dust emitted is a function of the grain handling rate, which
is considerably higher in terminal elevators. Few elevators are known to use
anything other than direct venting to the atmosphere, but it would certainly
be possible to aspirate the bins to an individual or a common dust collector.
Small fabric filter units have been used for this purpose in some metropolitan
areas. Some elevators exhaust the bins into the gallery or headhouse to pre-
vent escape of the dust into the atmosphere.
No data on emission rates pertaining only to bin vents were found during
this study.
151
-------
o.
Q
Q
LU
LU
U
LU
o.u
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
n i
/
/
/
>
/
/
y
/
o
/
o/
/
/
o
L
(
/-\
/°
nit D
1 GM
/
/
ensit
/cc
y
/
/
y
)is
Assu
ned
0.01 0.1 0.5
0.05 0.2
10 30 50 70
20 40 60
15 20 40 60 80
CUMULATIVE MASS PERCENT LESS THAN STATED DIAMETER
Figure 8. Particle size distribution of dust entering control
system serving a tunnel belt aspiration system
(grain elevator).
152
-------
Table 103. DUST EMISSIONS FROM GRAIN HANDLING OPERATIONS^
Item
Grain handling rate (bu/hr)—
Process weight rate (lb/hr)—
Source gas volume (scfm)
Duct static pressure (in. tL-,0)
At fan
At cyclone
Dust concentration (gr/scf)
Dust emission rate (lb/hr)
Emission factor (Ib/ton)
Inlet
9,000
540,000
10,000
- 3.9
+ 5.1
0.428
36.68
0.14
Exhaust
9,000
540,000
10,000
+ 5.2
+ 0.1
0.029
2.48
0.093
a/ Distributor head handling 4,500 bu/hr; front pit, back pit and legs
handling 4,500 bu/hr.
_b/ Computed as the product of the cleaning rate and the average bulk
density of No. 1 heavy dark northern spring wheat (60 Ib/bu).
153
-------
CO
25
O
H
o2
M
PH
O
O
3
Q
B
j
"3
o
i
CO
o
CO
CO
M
H
CO
Q
^
0
r-l
CU
, — |
rO
CO
H
„ .d
CO — ^
d pQ
O i — I
CO
W s-^
•r-l M-l
£ %
""-•*.
00
m
00
Os
o
o
is
o ^
--i e
P^l 4-1
O
CO CO
CO v— '
o
CO
r-l
o
«
i — i
i— i
0
•H
4-1
CO
O
O
>-l
4-1
CO
CU
H
4-1
CU
4-1
0
EC
m
CU
o
•r-l
J>
CU
0
r-l
O
5-1
4-1
d
o
CJ
^
r^>
CO
Q
1
CU CU
d -t-i
0 r-l
r-l CO
O CJ
CJ
5-1 O
CU 4-1
IW CO
co >
d i>
CO i— 1
5-1 i d co
CU -H t>0
> o cu
d CX r-l
o
CJ
[-^
oo
o
o
CO
1— 1
o
•>
1 — i
r-l
4-1
CU
1— 1
4-1
o
CU
d
o
i— i
o
CJ
r^
cu
M-l
CO
d
CO
5-1
4J
^
O
CU
^
d
o
CJ
EC
in
^1
to
O
i
CU
4-1
CO
O
o
4-1
CO
^
cu
, — 1
cu
CO
4-1
•H 60
O 0)
(X t-4
CN
^
m
0
C3
o
CM
vO
"
4J
CU
4-1
o
EC
in
d cj
CO r-l
5-1 > d CD
CU -H bO
r> O CU
d CX, r-l
o
CJ
m
m
o
0
o
CN
v£>
OS
4-1
cu
r-l
4-1
0
cu
d
o
1— 1
o
CJ
J_l
CU
CO
d
CO
4J
5-1
o
cu
P2
o
CJ
EC
m
^*l
CO
Q
1
CU
4-1
5J
CO
CJ
5-1
0
4J
CO
cu
r-l
CU
CO
4-1
•S
o
a.
CO
bO
cu
T—l
oo
u-i
O
O
O
O
o
CXI
C8
9
" S-i
CU 0)
0 4-1
O S-i
i— I CO
O U
5-1
O
o
•
o
o
o
4J
cu
i—i
4-1
3
O
O
CM
ca
9
cu *j
cu
^
d
o
CJ
4J
d
•H
o
CU
£>
d
0
o
4_l
£3
0
TI)
CO
o
r-l
*^s
5-1
CU
M-l
CO
d
CO
5-4
4J
5-1
O
cu
^
d
o
CJ
4-1
d
•i-j
o
o.
cu
d
o
o
4-1
£3
0
rrj
CO
O
1— 1
154
-------
FEED MILLS
Processing of grains and other ingredients into mixed feed consists of
converting the grains and other constituents into the form and size desired
in the finished feed, adding other ingredients and mixing them with the
grains, then forming a finished feed in the shape or consistency desired for
feeding. The basic forms of finished feed are mash, pellets and crumbles.
The latter are pellets which have been formed and then crushed or broken.
Feed milling uses two operations in the production of mash and four or
more in the manufacture of pellets. Grinding and mixing are the two basic
operations in feed milling. Pellet extrusion and pellet cooling are addi-
tional operations in the manufacture of pellets. If pellets are broken into
"crumbles" or "granules," the crumbling operation and screening follow pellet-
ing.
Feed Manufacturing Process
As shown in Figure 9, the manufacturer of feed begins with receiving of
ingredients at the mill. Over 200 ingredients are used in feed manufacture.
These include grain, scrap material such as meat scraps, bone meal, beet and
tomato pulp, minerals which are used in very small portions, medicinals, and
vitamins. Grain is usually received at the feed mill by truck, railroad, or
in some cases, boat. Materials received in bulk, such as whole grains and
soybean meal, are unloaded by gravity, air, or mechanical means. Frequently,
power shovels are combined with hand labor to unload railroad boxcars. Bob-
cats are also used in many cases. Large feed mills sometimes employ boxcar
unloaderso These machines lift the entire car, tilt it to one side, and then
discharge the contents through the side doors.
Barges generally are unloaded by positive or negative air systems. Truck
shipments usually are unloaded through the rear tailgate after elevating the
truck body to 30 or 45 degrees. The cargo is dumped through a grate into an
underground pit or onto an underground conveyor.
The actual movement of ingredients within the mill usually is done by
gravity. First, however, the grain must be elevated above the highest pro-
cessing machine before the gravity process can begin. This is accomplished
through the use of bucket elevators.
For horizontal movement or slight elevation, a feed mill may use a
screw-type conveyor, made of mild or stainless steel; a drag conveyor,
in which single or double chains haul grain along a stainless steel chute;
a continuous belt, with a V-trough in its center, or an air system, in which
grain is carried along in a jet-like stream of compressed air.
155
-------
ail
si
3 *
S 5 •. [ , . a
0. g if n
"555-
3 8 «883
i! i
plPliii
S|jj|j$
SsittS tSiS
£
$,,,-.-„„,
ill
!;S1Si335
Uj ,
in ' °
,_}» . 32 '». s
ip~n""
5»Sss!3sa
' ;
I
S«a»£»fiS S
S -wn^o^f-O
J-L-
i!!
5 y * s .
J3j:ISS
!
Jj! 1 o»o-vS
3S1-5 "5
:P"'^SS|i
^^5?Siii § 2 z
J««JS8»-»0
(I li 'si,
IrlillHl
i»!Sli!i
=S«8^SS^S^
a (.1
jil
39"»"8»S""
i-lllMj
J • * £ * * i
1 P^'° &^
B
T)
OJ
O
M-4
I
S-i
W)
(fl
•l-<
•o
O
1— I
4-1
d
-------
Most mills direct feed ingredients, especially grains, through cleaning
equipment prior to storage. Cleaning equipment includes scalpers to remove
coarse materials from the feed ingredients before they reach the mixer.
Separators, which perform a similar function, often consist of reciprocating
sieves which separate grains of different sizes and textures. Some mills
employ these units to rough grade grain as to quality and weight.
Magnets are essential in the feed processing line. Most mills install
them ahead of the grinders and at other critical locations in the mill system.
They remove tramp iron, bits of wire, and other foreign metallic matter which
could harm the machinery and contaminant the finished feed. Both permanent
and electric magnets are used. Chute and rotary magnets are also commonly
used.
From the cleaning operation, the ingredients are directed to storage.
Bulk ingredients are stored in concrete silos, steel tanks or wooden bins.
Wooden bins are generally found only in older feed mills.
Whole grains are ground prior to mixing with other feed components.
The hammermill is the most widely used grinding device. The grinding chamber
consists of rows of loosely mounted "swing" hammers or plates of hardened
metal. These hammers pulverize the grain by striking it as they swing. The
pulverized material is forced out of the mill chamber when it is ground finely
enough to pass through the perforations in the screen which is a part of the
mill. Several sizes of screen openings are used, depending on the fineness
of the end product desired.
Mixing is the most important process in feed milling and is prevalently
a batch process. Ingredients are weighed before mixing. Micro-ingredients,
such as trace minerals and drugs are weighed on bench scales. Some of these
are used in very small amounts--one, 8-oz/ton of feed.2.' Ground grain and
materials added in comparatively large amounts, such as wheat middlings and
soybean meal, are weighed in a hopper scale with capacity corresponding to
the capacity of the mixer--! to 3 tons. In large mills, 200 tons/day and
larger, ingredients are moved by conveyor from bins to the scale. In
smaller mills (30 tons/day) a "weigh buggy," which is a hopper and scales on
wheels, is generally used. A weigh buggy has a capacity of about 1,000 Ib
and is wheeled around under the bins from which ingredients are to be drawn
for a given mix. After the ingredients are weighed into the buggy, it is
wheeled to the mixer where it is unloaded. Liquids, such as vitamin feeding
oils, fish solubles, molasses, and fat are included in the ingredients fed to
the mixer.
Mixers may be either a vertical or a horizontal type. Vertical mixers
utilize a screw to raise the ingredients from the bottom to the top of a mix-
ing tank through an axial pipe from which the ingredients flow out, into and
157
-------
back to the bottom of the tank. Horizontal mixers move the ingredients in a
horizontal direction with right- and left-hand, narrow helical ribbons or
paddles attached to a shaft. The paddle-type mixer is more suitable when the
molasses content of the formula is high (30-40%) or for continuous instead of
batch mixing. Horizontal mixers have a higher mixing rate than vertical
mixers and are used in large feed mills. Horizontal mixers are provided with
a surge hopper underneath the mixing chamber so that the mixing process is not
interrupted by conveying the mixed feed to storage. A mixer and its scale
are sized to provide simultaneous weighing of the ingredients in the scale
hopper, mixing the ingredients in the mixing chamber, and conveying the mixed
feed from the surge hopper to storage.
The material from the mixer is a meal, or mash, and may be marketed in
this form. If pellets are to be made, the meal is steamed prior to being
pelleted.
Pellet making is an extrusion process in which steamed meal is forced
through dies. Pellets are usually 1/8-3/4 in. in diameter and of similar
length. Pellets must be cooled and dried after extrusion. This is accom-
plished in pellet coolers through which air at room temperature is drawn.
Pellet coolers are of either horizontal or vertical types. Vertical coolers
are less expensive with regard to both purchase and maintenance cost.
Horizontal coolers may be used where space is not available for vertical
coolers, and horizontal coolers are more satisfactory for feeds with high
molasses content. Feeds with high molasses content are often dusted with
bentonite or cottonseed meal to prevent caking. Cooling air is usually
passed through cyclone dust collectors.
If pellets are to be reduced in size, which is necessary for such use
as baby-chick feed, they are passed through a crumbier, or granulator.
This machine is a roller mill with corrugated rolls. Crumbling is a more
economical method of producing small pellets than using dies with the req-
uisite-size holes because the use of small dies seriously restricts
production. The roller mill is usually located directly below the cooler
and is provided with a by-pass for use when pellets are sent to storage
without crumbling. Crumbles must be screened to remove fines and oversize.
The product is sent to storage bins and pneumatic conveying may be used
for this materials handling process. Finished feed is bagged by automatic
bagging machines which are equipped with scales or is shipped in bulk in
trucks and railroad cars.
158
-------
Air Pollution Sources, Emission Rates, and Effluent Properties
Dust emissions in feed mills result from a variety of grain and in-
gredient handling and processing operations. Unloading of bulk ingredients
is generally acknowledged to be one of the most troublesome dust sources in
feed mills.—' Centrifugal collectors used for product recovery and dust
control represent the second largest emission source. Cyclones on pellet
coolers and cyclones used as product collectors on pneumatic conveying
systems are the most important sources in this category.^.' Pellet coolers
can be operated without being notably dusty; however, where a powder, such
as cottonseed meal, is being used to prevent caking of the pellets, dust
emissions may be profuse. Dust emissions from storage bins depend upon the
size of the bin, the rate at which it is filled, and the method of conveying
the material to the bins. A large bin which is being filled slowly through
a chute from a distributor can act as its own settling chamber. Bulk load-
ing, particularly loading of meal, can be a significant source of dust.
Loading through chutes into either railcars or trucks exposes the product
to the action of the wind. Loading a boxcar with a flinger which throws
feed from the door to the end of the car can be a very dusty operation.
Specific operations in feed mills are discussed in more detail in the
following section. Each operation is treated as an individual source with
no consideration of common ducting or external-internal venting options.
Ingredient Receiving - The ingredient receiving area represents the most
serious dust emission problem in most feed mills. The truck and rail re-
ceiving stations present difficult dust control problems. The two principal
factors that contribute to dust generation during bulk unloading are wind
currents and dust generated when a falling stream of material strikes the
receiving pit.
The ingredient receiving area can be broken into separate areas, each
with a specific set of dust control problems. These areas are:
(a) Bulk unloading
1. Hopper car receiving
2. Boxcar receiving
3. Truck receiving
(b) Materials handling equipment
(c) Scales
(d) Cleaning and scalping equipment
159
-------
The dust emission problems of the individual operations in each area
parallel those discussed in the section, Air Pollution Sources, Emission
Rates, and Effluent Properties, for the similar operations in grain elevators.
However, in feed mills a slower rate of materials handling is usually em-
ployed and a much wider range of materials may be handled. Meager data are
available on the rates of emission from the above operations in feed mills
because little, if any, source testing has been done in feed mills. Table 105
presents estimates of emission rates from various sources in the ingredients
receiving section of a feed mill.—' These estimates were obtained from data
submitted in response to the emission inventory questionnaires sent to selected
feed mills. Since the data in Table 105 are only estimates and were provided
by a limited number of feed mills, the emission rates should be used with
caution and only as order-of-magnitude numbers.
Factors affecting emission rates from the ingredient receiving area of
a feed mill include the type of grain and other ingredients handled, the
methods used to unload the ingredients, and the configuration of the receiv-
ing pits. Emissions from the materials handling and cleaning equipment are
dependent primarily upon the cleanliness of the received material and the
type of equipment utilized.
Table 105. ESTIMATED EMISSION RATES FOR INGREDIENT RECEIVING
OPERATIONS IN FEED MILLS
Uncontrolled Controlled
Emission Emission—'
Source (Ib/hr) (Ib/hr)
Ingredient unloading by
front end loader 32 3
Truck receiving pit 6.5 0.6
Receiving scale 3 0.15
Grain cleaner (milo) 750 60
a/ Cyclones used as the control device. Rate of material handled was not
reported and emission factor in terms of pounds per ton could not be
calculated.
160
-------
Because of the wide variation in ingredients that can be and are used
in the manufacture of feed, the nature of the emissions is also highly
variable. This is especially true of the emissions from the ingredient un-
loading areas.
Grain Processing - Hammermills, roller mills, cutters, and granulators are
often used in the grain processing section of a feed mill. Hammermills
present a dust problem due primarily to their product conveying system.1*12'
Most hammermills are installed using a conventional attached or separate fan
and cyclone collector as the finished product recovery system. The product
recovery cyclone is the major dust source in the grain preparation opera-
tion. -iii-L2-' Dust emissions will vary with the type of grinder (standard or
full circle screens), products being ground, and the method of conveying
finished product.
Standard type hammermills utilizing 180 degree screens will normally
require minimum air flow through the screens in the range of 500-1,000 cfm
per hammermill to maintain proper grinding action, eliminate back pressures
in the mill and for heat removal.
The full circle or 360 degree screen hammermill may or may not require
air for proper grinding action. Normally, on coarse grinding, no air will
be required, however, on fine grinding applications, air may be required to
control internal temperatures even where dustiness is not a problem, or it
can be controlled by adding moisture during the grinding process.
Most grains being ground coarsely for mash type feeds do not present
a particularly bad dusting problem. However, when fine-grinding alfalfa
pellets and some grains (barley, wheat, milo) for pelleted type feeds,
dustiness can become a much more severe problem.
As noted previously, the method of conveying the finished product has
a major influence on dust emissions. Products from hammermills can be
handled by:—'
(a) Gravity system (direct flow to bin)
(b) Mechanical system (conveyors and elevators)
(c) Positive pressure pneumatic system (high pressure)
(d) Negative pressure pneumatic system
(e) Fan attached to mill shaft (negative and low positive pressure)
(f) Separate fan located at mill (negative and low positive pressure)
161
-------
The gravity system will produce the least amount of dust emissions while the
separate fan system will normally be the most "dusty" system.
Many of the older feed mills do not have provisions for controlling the
dust emitted from the handling of the hammermill products. Older mills that
use pneumatic conveying of the product are generally equipped only with a
product recovery cyclone, and dust escaping from this cyclone is vented
directly to the atmosphere.
Recently obtained data on emissions from various product recovery systems
on hammer and attrition mills in feed mills are shown in Table 106. EPA con-
tractors using EPA Method 5 and, in one case, a hi-vol sampler, obtained the
data reported in Table 106. As shown in Table 106, emission rates determined
by EPA Method 5 and the Rader Hi-Vol sampler are not in agreement. The Rader
Hi-Vol sampler measured significantly lower emission rates. No explanation
of the differences was offered by the EPA contractor performing the emission
testing.,
Storage Bins - Suction venting on storage bins is not a common practice in
feed mills, except in newer mills. Most older plants vent storage bins to
the atmosphere or to the interior of the mill.
Mixing Areas - Dust emissions in the mixing areas are normally not a problem.
Primary means of dust control are through the use of fully enclosed systems,
and providing for adequate interventing of displaced air due to rapid dis-
charge of scales and multiple or drop bottom discharge mixers.—
Pellet Mills and Pellet Coolers - The pellet mills do not present a signifi-
cant source of dust emissions. However, the pellet coolers are a source of
dust and they present control problems because of the moisture content of
the air stream leaving the coolers. In a pellet cooler, the moisture con-
tent of the material is reduced from approximately 17% to 11%. The flow
rate in older mills ranges from 6,000-14,000 cfm in the coolers while in
newer plants 15,000-30,000 cfm are common. A rough rule-of-thumb for these
units is 1,000 cfm/ton of pellets per hour.—'
Table 107 summarizes results of recent tests by EPA contractors on
two types of pellet cooler. EPA Method 5 was used in all the emissions
tests. At Plant A, two of the emissions tests were conducted while a beef
cattle feed containing 5% molasses was being pelletized. The pellets were
dusted with 500-550 Ib of calcium carbonate applied at a steady rate. The
high outlet grain loading and visible emissions are a direct result of the
dusting operation.
Figure 10 presents particle size distribution data for the particulate
emitted from the cyclone on the horizontal pellet cooler at Plant B (Table 107).
162
-------
kO CM CM
co CM t-(
O O O
!
. cd 0) u~i
O O O O M-l
o c o o
9 2 & P T
r-l C M O 0> -W
o) nj ft. o M —t
TJ i*-i a; cfl -H
I a § " » •"
' v- * H ti S 2
QJ CM 3 O rfi
, 4J ^ - TJ rH 4-1
^H r-1 S O O
fc4 r-. o o, o 4-i
O O O
oo c» oo
163
-------
CO
r-l
a
p
w
w
Pn
H
CO
rf
o
o
o
d
p-
g
1
CO
w
H
3
o
H
CO
CO
tj
s
w
fV]
to
^
w
y|
.
t^-
o
1-1
(0
£>
to
£-1
to
01 a
r-l O
•H to
to to
•r( T4.
> 1
"5
o
4J
JO
4J r-l
HI ^
rH
4J
O '— •
U
to
c s
•H ^
lfl
3 -3
•u, 2
to -v.
a 5
01
a
MH
u
in
3
Hi
u
&%
to --v.
to C
dJ O
O 4J
o ---
OH
T3
01
01
01
H
C
01
p
•H
3
o-
Ed
w
to
01
O
O
£
Jj
o
01
o
3
o
CO
X
•rl
0
to
a
o
. 0 „
o o
in in 01 oi 01 01
iid d d d
m in o o o o
r-l r-l 2! S5 S5 tS
CM oo r~
in o m
r-l O> r-l O i— 1 O
CM CO i-l 0 0 O
00 CM CO
CO '•O ^D O O O
r-l t-l o O O O
O O 0 O O O
CM CT\ *£> O i— 1 in
oo I-H r^ i— i o^ oo
r-l >d- CM <]• in CM
CT\ 00 O CTl O 00
oo vo r-
ra
•r4
d T3
O •
j3 . d
60 41 -H
d cu to
O >* *rl 00
« r-l
1-1 d 01
c o -1-1 d
0 rJ 0
r-H O CT» i— 1
O CO l~~ O
o o
4J
0) OO
rH G
i-l -rl
01 > M
ft 0 01
S i— i
r-( ^~- O
to o cq
-------
a.
a
UJ
LLJ
o.u
5.0
4.0
3.0
2.0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0 1
UN
IT
5EN
JSITY
(lc
PEL
jm/cc
LET CC
:) IS A
DOLER
.SSUM
CYCL(
ED
/
/
)NE
/
/
O
/
/
ox
/
/
/
c
/
/
(
/
0.01 0.1 0.5 1 2 5 10 20. 30 40 50 60 70 80
CUMULATIVE MASS PERCENT LESS THAN STATED DIAMETER
Figure 10. Size distribution of particulate emitted from cyclone
controlling a horizontal pellet cooler (feed mill).
165
-------
A Brink Model B cascade impactor with a back up filter was used to obtain the
data. According to the data presented in Figure 10, the mass median diameter
of the particle distribution is 1.6 u.
Emission tests conducted on pellet coolers at a feed mill in Texas are
summarized in Table 108. The sampling and analytical procedures used followed
the procedures outlined in the "Compliance Sampling Manual," Texas State
Department of Health, Air Pollution Control Services, January 1972. There
are four horizontal coolers (screen conveyor type) at this feed mill. The
emission rates in pounds/ton of product shown in Table 108 for the horizontal
coolers are in general agreement with the data reported in Table 107 for the
horizontal cooler at Plant B. However, the horizontal cooler at Plant A
(Table 107) had a significantly higher emission rate even when a feed mix
that did not require dusting with calcium carbonate was being processed.
The data in Tables 107 and 108 make it appear that emissions from
cyclones on horizontal coolers exceed emissions from cyclones on vertical
coolers. This result is at variance with the personal experience of many
feed mill operators.!P_iA2/ (See Table 109.) Operators of feed mills generally
list the vertical cooler as a far more significant emission source than the
horizontal cooler. Since only a limited amount of reliable emission testing
has been conducted on cyclones on pellet coolers, definitive conclusions can
not be reached regarding the relative importance of the two types of coolers.
Load-Out Operations - While the bulk load out of finished feed does not
usually involve inherently dusty materials, load-out operations still present
a major source of dust emissions at feed mills. Bulk loading of trucks and
railcars is done in a number of ways all of which fall into two basic cate-
gories.
(1) Gravity filling--material is moved by pneumatic or mechanical con-
veyor systems or discharged from overhead bins or scale hopper dropping
directly into car or truck by gravity through a suitable connection.
(2) Pneumatic filling—material is conveyed by air (positive pressure)
directly to truck or car without use of a collector to separate air and
material.
The main causes of dust emissions when loading bulk feed by gravity into
trucks or railcars is the wind blowing through the loading sheds and dust gen-
erated when the falling stream of feed strikes the truck or railcar hopper.
The wind velocity through load-out sheds and between bins is normally greater
than that of the average wind velocity in open areas near the mill.
Loading of bulk feed into cars and trucks with a positive pressure system
(pneumatic) requires a tightly closed system. Since the system must be tightly
closed, the wind in the area has no effect at all on dust control.
166
-------
rJ
rJ
H
a
o
W
W
En
CO
S3
w
H
H
CO
rv|
PH
, "]
0
O
u
H
W
hJ
j 1
W
PM
O
N)
M
Pi
O
a
o
Pi
En
CO
Ed
H
PM
0
M
CO
CO
a
w
o
§
p
in
<^
pj
S
•
oo
o
CU
rH
,n
co
H
C
O
4-1
60 ,0
C rH
•H N-— '
o*J o^ O csi
ro \D LO ro
O O O O
TJ 4J
CO CU
O rH
rJ W
CO s-^.
an t
0
CO
•-^
£j
60
vO v£) CM
co o *»o -
CO /-N
Pi i-l
.r!
CO --^
CO fi
cu o
0 4J
0 ^
M
PH
in o ^ " ?**>
rH S-| CN M
4J 4-1
• ^-1 .t—l
O3 O 3
pi , QJ
r-l M
CU 60 Ol 60
rH C rH C
0 TH 0 -H
O CO O CO
CJ CO O CO
01 0)
4J CJ 4-J O
CU O 0) O
1 — 1 M 1 — 1 r-l
1 — 1 ft 1 — 1 ft
CU 01
PM PH
~CO| "
CTs CN Q\
CN CN CO
O O O
-^
oo oo
o") ro *^
0 O O
o' o o*
0 0 O
<}" LO CSl
r-l i— 1 T—l
CM CO i— 1
-•^
1
c
o
o
rj
'O
0)
« CU
n m
• MH
o cu
fe; cu
fi
j_i
CU 60
rH C
O -i-l
O cfl
CJ Cfl
cu
4J CJ
0) O
t—l ^j
rH ft
cu
PM
C0| "cO| ~TO| ^01
LO f"^ r^*- *4H
O
0)
5 §
CO
C
o cu
CU 4-1
C
O CO
rH -H
O
>> C
CJ J5
O
O co
Cfl
Eq
C0|
167
-------
Table 109. ESTIMATED EMISSIONS FROM PELLET COOLER CYCLONE SYSTEMS^'
IP./
Gas Flow to
Cyclone(s)
System (cfm)
A. Vertical cooler
(a) single cooler 13,000
--single cyclone
22,000
11,425
22,000
28,000
16,000
10,000
19,000
(b) single cooler 36,000
Mass Loading
to Cyclone(s)
(lb/hr)
56
100
49
95
400
100
50
200
155
Emission from
Cyclone(s)
(lb/hr)
6
8
5
10
40
5
10
10
16
--5 cyclones
B. Horizontal cooler
with single
cyclone
6,600
30
168
-------
ALFALFA DEHYDRATION PLANTS
Alfalfa dehydration is a relatively new industry as the dehydration of
alfalfa did not begin to be of commercial importance until the 1930's. Alfalfa
dehydration plants are relatively small operations that receive fresh cut al-
falfa from the fields and dehydrate it in a rotary drum that is usually gas
fired. Harvested alfalfa can also be processed by sun-curing but the sun-
cured product generally contains only about 147° protein whereas the dehydrated
product contains 157o to 207, protein and also retains more Vitamin A. Generally,
sun-cured hay is lower in protein because it is usually harvested at a more
mature stage and more leaves are lost in the sun-curing process than in de-
hydration.
Alfalfa Dehydration Process
The first step in the alfalfa dehydration process is the field operation
of harvesting. At harvest time the standing alfalfa is mowed and chopped in
the field and transferred to a dump truck. The truck carries the "chops" to
the dehydration plant (usually less than 10 miles away) where they are dumped
onto a self feeder which carries the chopped alfalfa into the drying drum.
The drying drum is a slowly rotating drum that is fired with natural gas
or oil. Combustion air flows into the drum by the induced draft fan (primary
blower) as shown on the generalized process flow sheet (Figure 11). The
temperature at the drum inlet is about 1800QF and the outlet is approximately
275°F. Drums may be single pass or triple pass. Subjecting the alfalfa to
the hot gases in the drum evaporates the water to dehydrate the alfalfa from
its original moisture content of about 807, down to 8 to 1070. The exhaust gases
have a high moisture content (307») and also entrain the finer particles of
alfalfa. The effluent may also contain odors from volatile matter driven off
the alfalfa in the drying process.
The high moisture gases and dry product from the drum enter the primary
cyclone which separates the product from the gases. The moisture laden gases
discharged to the atmosphere represent the first, and perhaps the largest
source of particulate emissions. In some plants, the fan or blower is between
the drying drum and the primary cooling cyclone (referred to as a positive
pressure system). In other plants the blower may be located in the outlet
line from the primary cooling cyclone (negative pressure system).
The material separated in the primary cyclone next enters the grinding
machine, normally a hammertnill. The grinder reduces the dehydrated chops to
a powder referred to as "meal." From the grinder the meal enters the nega-
tive pneumatic conveyor that discharges into the meal collection cyclone. The
cyclone is intended to separate the meal from the conveying air and to accumu-
late the meal in the meal bin feeding the pelletizing system. In some plants,
169
-------
c
TO
<-4
o,
C
O
•H
•U
TO
S-i
-a
TO
i—l
TO
O
e
60
I
0)
N
•r-l
C
(U
Q)
t-i
170
-------
the air from the meal collection cyclone is drawn through a fan and discharged
into the secondary meal collection cyclone in an attempt to recover meal that
escapes the first meal collector.
The meal accumulated in the meal bin is fed through a steam conditioner
prior to entering the pellet mill. The pellets from the mill are pneumati-
cally conveyed to the primary pellet collection cyclone from which they are
fed into the pellet cooler. The air exhaust from the primary pellet collec-
tion cyclone enters a fan and may be discharged through a secondary pellet
collection cyclone.
In the pellet cooler a flow of ambient air is drawn through a downward
moving column of pellets to cool the pellets prior to bagging or transport
to bulk storage or bulk loading. The air from the pellet cooler picks up some
moisture and heat from the pellets. This air is discharged through a fan to
a pellet cooler cyclone.
The process flow described above and depicted in Figure 11 is a general
example for an alfalfa dehydrating plant. However, there are several varia-
tions in the process scheme that are used. For example, the pellets from the
pellet mill may be mechanically conveyed to the pellet cooler, thereby elimi-
nating the pellet collection cyclones. As another example, some plants duct
all the cyclone effluents back to the primary cyclone so the only discharge
point is from this primary cyclone. Another process variation included in
some plants is the addition of vegetable oil or animal fat to the alfalfa
meal at the hammermill. This oil helps to minimize the dust produced in sub-
sequent handling and storage operations.
Air Pollution Sources, Emission Rates, and Effluent Properties
Emissions from alfalfa dehydrating plants include dust from the various
cyclone separators, and odors from the volatile matter driven off the alfalfa.
In comparison to the other segments of the grain and feed industry, a
significant amount of source testing has been done to characterize the
emissions from dehydration plants.^> ^' Midwest Research Institute has re-
cently completed two source testing programs for the Alfalfa Dehydrators
Association (ADA). References 13 and 14 present the results of the testing
programs in detail and a summary is given in the following paragraphs.
Reference 13 describes the field testing program conducted by MRI for
the ADA during the summer of 1971 at four plants which had been selected by
ADA as representative of this industry. Particulate emissions and process
conditions were measured at the four alfalfa dehydrating mills for both
normal and extreme process operating conditions. The general characteristics
of the four plants are shown in the simplified flow diagrams presented in
Figures 12 to 15,
171
-------
O
D
o
. in
bO
E
o
L_
Q
-------
c
o
o
o
o
O u-
°0
in CN
U"> CN
O uj
E
-------
JH
bO
§
,-1
MH
O
c
CO
>*
I—I
-------
cfl
S-i
bO
to
•H
T)
g
CO
J-l
1
E>
W
O u-
0 . o
LO O
~ 1 CN
•
-------
Two types of source tests were performed to determine, respectively,
(1) the particulate emission rate from a given source, and (2) the particle
size distribution of the dust emission. The emission-rate test consisted
of the measurement of effluent flow rate and temperature, dust loading, and
carrier gas composition (moisture and Orsat analysis). For these measurements,
EPA Method 5 and the Research Appliance Company Model 2343 "Staksamplr" equip-
ment were used. Integrated particulate samples representative of the entire
duct cross section were collected by sampling for equal amounts of time over
a network of properly distributed points. For each test the duration of
sampling ranged from 30 to 60 min so that short-term fluctuations in emissions
were averaged out.
For the dust sizing tests, an Andersen in-stack impactor was mounted on
the end of the sampling probe. The Andersen impactor measures size distribu-
tion in situ thereby eliminating particle agglomeration problems encountered
when dust samples must be collected and transferred before sizing analysis.
Table 110 indicates the process parameters that were measured during test-
ing and the method of measurement. These parameters have been classified into
three groups: (1) raw materials, (2) product (pellets), and (3) process operat-
ing conditions relating to drying, grinding and pelleting of the alfalfa.
These quantities were measured periodically during testing.
Tables 111 to 115 present the results of the emission rate tests for the
four plants. Plant A, as shown in Table 111 was tested under normal operating
conditions with the full plant in operation (Test 101), and with the pellet
mill shut off (Test 102). At Plant B, tests were conducted to determine the
effect of changes in certain process conditions on the dust emission rate--
namely, the effects of overdrying the hay (Tests 201 and 203), varying the
process weight rate (Tests 202 and 209), and operating water spray systems
(Tests 204 and 211). The size distribution of dust emitted under normal
operating conditions (Tests 205A and 210A) and the mass flow rate of dust in
the two major recycle streams (Tests 206 and 207) were also measured. In one
test (208), the dust emission rate was measured with only the dryer operating
but with the other air flows maintained. The results of these tests are given
in Tables 112 and 113 and Figure 16.
Table 114 and Figure 17 present the results of tests conducted at Plant C.
Tests were conducted to determine the emission rate (Tests 302, 305, and 307)
and size distribution (Tests 301A, 303A, and 308A) of dust from each of the
sources under normal operating conditions. The effect of overdrying was also
measured (Tests 304 and 306).
At Plant Q tests were conducted to determine the emission rate and size
distribution from the three sources shown in Figure 15. Test resuts from
Plant D are presented in Table 115 and Figure 18.
176
-------
1
fXj
O
Q
Q
"^4
S
<
T
H"J
^3
r*4
O
fe
CO
1
i
w
M
O
§
Pn
*
O
^J
r— H
cu
43
TO
H
O
43 cu co
4-J O 4-1
0 CU
i-l -H >
4J TO ~, dcu gcu-H cubObO>~.
d4-l T-IO OJ3CO Odd4J
•r-l -1-4 g d CO Vl 4-J >, d -H -i-l -i-t
T3O ViTOft £>*» T— 1 TO'OTIJCJ
TOO CUi-10 fti-ITO T-4TOTOO
Qji-l 4-ITO3 TOC TOCUCUi-l
MCU CUJ313 i-l -H TO JSViViCU
> T3 TO Vi >
Vl OCU 03-UOViVi
01 4-1 (Ui-i -HUTO CJCUCU4J
4JCJ J2 C CO 4JVICO d 4J 4J U
CU3 TOCUO ftOJVi ^*» ^» TO TO
ja 43 42 vi vi
4J 4J 4J 4-> 4-1 4-1
d d vi a a a a
cu cu 43 cu cu cu cu
00 CJCJ-~~- O CJCJO0
M-IM-I VlVid Vi MViJ-i*
OO CUCUO feP^Q) CUCUQJO
OQ co f j p< ) [ i o o f\ [ p | p ) p [ (^
TH T3
TO CU
d cu
t . ii i
cu cu
4-1 M CU i-l
cu cu d 3 M 1-1
4J 4-1 -H 4J 3 •!-<
TO TO TO 4-1 0 4-J
ViVi !ViTOVi4Jdca
cu vi cu d cu cu
d^ 4-J cacoftcu g a) M 4-)
oo 4Jdcu dd0ft g VIMTO
•Hi-l dCU4-l OOCU0VITO V(3Vi
4JM-I x-^CUWTO -r-l-T-l 4-!CU'-l43,^3O
ft C04-ldVl 4J4J 4JTO en O >
0M 4JdO -i-l -i-l CU Cft i-lO
3-T-) CUOOd T3t3O4JCO-i-IOT-lT-^ViiJT-l
I N-^CU4-I3 bOVifnOW-UViCUCJCJ
i-ICU 4JCOTJ dCU COT30T--, -T-l v— '01— 1 CJ
3TO OViOVi 4JJ^«**O TOCUCU
P4^1 3P4SP-I TOMl — ICNICOSl PdP-lCrf
*^J J_J
O CU
• • !«(••• f^[ • • • * •
PQU PL,
-------
ml
rh
%
O
M
tO
CO
1— 1
§
d
0) CU
_3 ti
r-4 CO
>
O O !H
vo ro ro
n «\ 0
J ° ° w
w •* -* 6
Q| t-l i-l O
M
M-I
d
CU
CU
i-i
o
CU
ui LO bO
H
ro sf CO
r~- r~~ 43
O
CO
•r-i
T3
ri.
^^
B~?
s —
i~*>
O
4J
0
i • cu
1 vD 43
i — 1 4J
1
4J
a
. i
^^
i-i
43
43
i-H
^w'
-i-i
a
o o
o o d
vO 00 O
« «, -r-l
1-H ^H CO
CN CM CO
•H
e
cu
CU
d
o
•H
4J
CO
i-l
CD
ft
O
a
~~^~ o
,-1 § CO
CO ^ CO
4-1 43
0 +
H <
Q
4J
d
CO
^
PH
4J
CO
CU
H
i-< CM
O O *•-.
r-l i-l Cfl|
•
s-+^
M
CU
>%
«J
W
T3
cu
42
4J
bO
C
•H
f.
W
0)
4J
d
CU
CO
ft
o
.d
o
d
-i
43
^Q
I— 1
n
•
CU
•
•H
N^X
CU
4-)
CO
Cd
4-1
43
bO
•H
(U
J2
CO
CO
0)
o
o n
M CU
PH >•>
M
1 T3
£? '
PH Q
^ s^^
f>\ ol
,— (
r-l
•H
0
p
CU
CO
43
I
s
178
-------
s
o
•H
co
co
•H
I
r-» oo en oo
oo m vo i~s
I CO CM I OO
faO MH
•u ri o
tn -H nj
3 "d -^
Q ctf j-i
O 6C
r- oo i—i vo
OO r-l CO VO
o o o o
in oo
o in
o o
VD
1
o
M
PQ
H
PM
O
H
H
p
s
a
CN
43
CO
H
cu 01
3 4-)
1-1 rt
M-l (2
M-l
w
w cu
d. J-i
o 3
43 4J
CJ CO
•H
O
61
S3
•H
CU
4J
O
H
PM
J-i
43
4J
CO
CU
H
O O O O O O O
O O O O O O O
-i
vt oo CM in cr> co m
in in vo in in in in
o o in o
oo in in o
i-l i-l CM
m o m o o
o o o
vO i—I CM
CM CO CM
\
>,
t— i
£j
0
n
r-l
cO
4-1
O
H
i-l
cO
4J
O
H
r-(
cO
4-1
O
H
ooooo o o i-i <-i
CMCMCMCNCN CMcvlCMCN
01
C
0
( 1
u
o
J-I
CO
6
•H
J-i
a.
0)
4-1
6
0
j-i
M-l
0)
60
CO
t~?
O
CO
•H •
T) Jj
CU
fX 'O
o cu
4-1 CU
01
43 C
4J -r-l
1
| JXj
4-1 CO
£3 J-i
•H a
O CO
a.
^_i
C 0)
0 4-1
•H CO
CO &
CO
•H 43
6 -u
a> .H
[5
Cl)
C T)
O 0)
4J
CO O
CO 3
43 -0
a
m o
CJ .
(3 4-1 CU
CO CO £*,
r-^ CU U
PL, H Q
.
4J
C
CD
-3
i— 1
M-l
4-1
CU
CU
K>-1
J^
13
m
o
60
C
•H
42
3
O
CO
cu
4-1
CO
^
*o
Q)
i-l
t— 1
0
J-i
4J
a
o
o
f-j
4-1
•i-l
&
•a
cu
4J
o
3
-o
O
O
4J
CO
CI)
H
179
-------
en
g!
O
I-J.
c/l
CO
g
O
§
^3
,_3
P-4
•%
13
O
H
H
^3
PM
Q
S-j
pj
w
Q
•
r^
o3
H
CO
d
o
•rJ
to
CO
•H
60
d
4-1 -rJ
CO T3
5 CO
0
^
4-1
d
Ol Ol
3 4-1
i— 1 cfl
4-1 fs*|
4-1
W
<"5
^
0>
CO VJ
0. 3
O J-l
U 'r-l
O
a
d
•rJ
CO
4J
0
^J
PM
Q^
^
P4
— • ,
d
o
•rJ
4-1
CO
VJ
0)
0,
0
01
o
VJ
o
CO
_, s
^_J
43
^^
43
i— I
1 1 — •
1 •
CM
r-l
J 00
Q ,
CO
e
•H
VJ
ex
Q
o-
o
CO
I-l
cfl
0)
e
J>^
VJ
Cfl
13
d
0
CJ
0)
U)
"§
53
in
o
CO
1— 1
•
o
1— 1
m
00
m
o
0
o
o
CM
in
CO
I-l
m
P^
r^
i
i
O
O
.^f-
M
CO
CO
VJ
o
J-l
o
co
I-l
1— 1
o
CJ
I— 1
CO
co
3
!>*>
V-i
CO
^O
d
0
CJ
CJ
CO
5?
s
vO
O
CO
i— 1 CO 1
• • 1
^st" 1^"
CM Os
co oo
CM Os 1
vO CM 1
r-J 0
o o
0 0
r^ o i
n n 1
r-l 00
CO
m in o
oo ,
CJ VJ
VJ >, T) Vj
o vj d o
J-l CO O 4J
CJ g O CJ
0) -i-l 01 CO
r-l VJ to i-H
i-l CX -«» i-H
o -\ s o
CJ Q S O
r^ oo
O 0
CO CO
I— 1
CO
•rJ
4-1
•rJ
d
•I-J
o
r-l
Ol
4-1
4-1
CO
4-1
T3
co
01
•rJ
r™^
co
43
to
•I-l
4-1
H
.
$3
.
in
r-J
ft •
4-J to
CO d
0) O
4J TJ.
CO
4-1 CO
O -i-l
e
TJ CO
d
co d
•H
4-1
CO CO
to
• - Cfl
6-2 CO
OO Vj
• CJ
r- d
to
cfl i— 1
5 to
•H
01 JJ
VJ d
3 co
to to
•rJ 42
O 3
e w
•> 01
4-1 43
CO 4J
co
4-1 13
CO r-<
4-1 CO r-l i— 1
O D i-l ••-(
CO -rJ B
4-> U g
M VJ U
CO 0) VJ CO CO
4-1 VJ CO g rH
4-1 VJ CO
-------
o
M
CO
EM
Q
PH
gf
o
I— I
^
o3
Q
£
w
O
<
s
"2
fcj
l_3
<
in
r— 1
, — |
cu
r\
CO
H
CO
a
0
•H CU
CO 4-1
CO CO
I"
00
4-J C
CO -H
3 T3
Q CO
0
4-J
c
3 4-J
i-l (0
M-l pi
^4-1
w
Q
L>
cu
CO )-l
Cu 3
O 4-J
645
0
S
•H
CU
4J
O
CM
8^
r^
p_i
-^
C
O
•1-1
1 J
CO
^J
OJ
o
cu
CJ
M
3
O
CO
^— ^
J_4
j^
*\
i— 1
M-l
U
CO
I-l
or
^
•B
u
CO
"\^
>
(5
d
cu
CU
^j
o
-•— >
&*2
s«>
M
tj-j
-*-*.
tO
i— i
^- '
4->
C!
O
0
CO
CO
•t-l
FJ
W
-I—I
CO
0)
H
O^
v^
1 •
I 0
m
*2~
i
1 o
o
0
oo
1 "
1 1— 1
°. °.
<^ o
1— (
m o
*^
^-1 w H-i u u
•H CJ -i-4 O O
i— 1 i— 1 CJ
v-/ 4J v_x 4J v_/
CO CO
PL, 13 P-I T) PM
i-l CM CO
O O 0
in
^
f^»
00
•
r^s
i-i
O
o
r~
•s
00
CN
4-1 CO
O 0
cu -^
,__! ij
i-l O,
O*^^
J^y
s
4J
CO -J-
•0 Q
m
o
st
CT* in ^}- r*^
• • i • i •
CN ro CN r-i
oo CT< oo in
o o o o
• « 1 • 1
O O 1 O 1 O
o o o o
o o o o
OO OO CO O
„ * 1 » 1 *
i — i CN i r^ i ^o
*rt* *cf CO CO
o m m m m o
r~! in r~^ r-! r-^ oo
o m o o o o
\o oo r^- vo m o
r** r^ r^ r^ r*^ oo
o o CN o en oo
• •••••
r*^» ^o vo *«o in r***
i— 1 i— 1 i— 1 i— 1 r— 1 r-t
O O O O O O
O O O O O O
\£> CN i— i m m o
».•»*> »\ «*»
CN m st 1-1 ON i-i
CN CN CN CN CN CN
>•> >, >. >> >>
CO CO CO co CO
B e e e s
•H -i-l -i-l -H T-l
o 0,00.0 0.0 0.0 0.0
o^ o^o^ o^Jo^Jo
OJ j^i CJ pj O }TJ QJ |~r] ^J j~r| QJ
t— 1 i— 1 r-l i— 1 i— 1 i— 1
r-<-(-l— 1 + 1— l + r— l + i— l+i— I
cjQcjQcjQcjOoQcj
-^
**O r^* OO ON O
O O O O i-l
-( CO CU
CJ T3 Xi O.
4J 1 1 1
CO
cu s s
H Q S E
- —
Cfl|
182
-------
10.0
oo
z
O
y
5
LU
_J
O; w t
-X-l Test 205A ^L -—i—
0.1
Particulate Size Distribution
_.„ Plant B
Composite Dust J.._|—.J L
\
0.01 L
Figure 16.
PERCENT (BY WEIGHT) GREATER THAN STATED SIZE
Particulate size distribution, alfalfa dehydration, Plant B.
183
-------
ioor-"
i T Particulate Size Distribution .L HI
i O Dryer
'- D Meal
A Pellet
308A
301A
PERCENT (BY WEIGHT) GREATER THAN STATED SIZE
Figure 17. Particulate size distribution, alfalfa dehydration, Plant C.
184
-------
10.0
1/1
z
o
Di
u
Q
LU
__l
Particulate Size Distribution
oil—-. P|ant D
Dryer + Meal
Dryer + Mea
A Pellet
i V Pellet
O.OlL
PFRCFNT (BY WEIGHT) GREATER THAN STATED SIZE
Figure 18. Particulate size distribution, alfalfa dehydration, Plant D.
185
-------
The effects of changes in process weight rate were measured (Tests 405,
406, and 410), and a skimmer system (Tests 408 and 409A) which recycled dust
from the outlet of the primary collector back to the dryer furnace was also
tested.
The test results summarized in the preceding paragraphs show that emis-
sions from the drying operation comprise more than 757» of the total emissions,
and are the most difficult to control. Dryer emissions vary with process-
weight-rate, hay quality, dryer operations, and cyclone collector efficiency.
The effect of over drying is to increase substantially emissions from the dry-
ing and grinding operations.
Reference 14 presents the results of another field testing program con-
ducted by MRI for the ADA during the summer of 1972. In this second testing
program, benchmark performance data were obtained on two pilot-scale and
three full-scale wet scrubbers and on two full-scale control systems which
recycle effluent from the primary cyclone. More complete information about
these devices/systems and the testing results are contained in Reference 14.
The test results are shown in Tables 116 through 122. The test results pre-
sented in Tables 116 to 122 indicate that medium efficiency wet scrubbers
have the potential to bring alfalfa dryer emissions into compliance with
process-weight-rate standards, although problems of water clarification and
sludge disposal remain to be solved. The results also indicate that the
partial recycle of primary cyclone effluent back to the dryer furnace holds
promise for the significant reduction of particulate emissions.
The test data reported in References 13 and 14 can be utilized to cal-
culate emission factors. Tables 123 and 124 present emission factors derived
from the test programs conducted by MRI. Table 125 presents emission factors
derived from data presented in a separate study reported in Reference 15. The
emission factors shown in Tables 123 and 124 are expressed in pounds of dust
emitted from the collection cyclones per ton of alfalfa chops entering the
process. Emission factors for alfalfa dehydrating plants may also be reported
as pounds of dust emitted per ton of meal produced. To convert from one basis
(Ib/ton of chops) to the other (Ib/ton of meal) the following approximate re-
lationship can be used:
Pounds Dust , Pound Dust
x 4
Ton of Chops Ton of Meal
The multiplier of four (4) was used on the basis that the chops usually
contain about 77% water, while the meal contains only about 8% water. Thus,
100 Ib of chops will yield about 25 Ib of meal. Actual moisture contents of
the chops and meal should be used, if available.
186
-------
?l
*
H
CO
t*
co
Ctj
CJ
(— I
Q
§~
E ^
s
CO -M
W a)
« 3
H cu
CO rH
W crj
H 0
CO
13 4J
0 0
El -rl
o ^
Q
<
fc.
H-)
tJ
w
to
o; ^ ^-s
O -H S-S
x < ^
w
•a
G
w
1 &4 '—V
^ M^ ^
a aj o
co H ^~-
CQ
en
2:
O
M
H ,-J >,
M B-S H
a ^
O W
a -l CO
g 1
c
D. QJ
O 0)
-C t-4
u o
c
•H
0) ^-j
o ^
!H
C^
tn ^-.
w AJ M
a) .c a) jn
(J 00 4J --»
O •"-( cO ^3
M Q) ni r-.
CM S —
4-J
W
cu
H
bO
C
o o o -a
* « r, 0
, — i ,_( , — |
0)
4-J
CO
P
o
4_t
(TJ
IP-1
CM fsj (NJ
0 CO rH
04 ,-( in
0)
O CO O U
r-^ m m en
CM CM Oi CC
o
CO
o
M
H
J3| J2| Q
I« > « O
O i— t vTJ U
rH rH
CO
o
w
m a\ CN <; oo
. . . u >
OJ
to in f-/
00* CO* 1 B
T— 1 1— 1 [0
•H
J3
S
000
O 0 0
O oj cr- Q;
OJ CNJ ^ £_(
i-H PO \O
G
o
tf
H
61
4H~
U
(0
•~~-
6
/— x
a
CJ
ra
T3
.?
0
^-^
'i
^
^
>
,>
rO
^
'~V1
f*
4-t
W
0)
H
CO Oi CT- U"i OJ O
O r-l o> 00 OJ 00
rH O f-l O O O
O O 0 0 O 0
r- 1 ^ \£) rH I-. CO
o o o o o o
o o o o o o
IOJ rH
n r- *o oj r-*
O ^O O vO CO rH
(N rH CM ,— 1 i— 1 OJ
M O M O t— ' O
1 1 1 1 1 t
rH rH CO CO \O ^D
s
M 0)
nj N
Bi -H
O
a X
187
-------
™J
S
cn
-v.
o
h-f
W
Q
O
S 0)
0 Xi
CJ ,n
3
H 0
ij W
I3
W Q)
OS S
H a)
CO i— 1
w to
H 0
cn
O JJ
M 0
H r-j
Q Si
g
w
Q
fa
fa
•J
r^
r-l
0)
r-l
•JO
CO
H
«
C T3
o rt
•H ^ O O O O
4-1 U O O O ,J
V-l 4-1 •**. *i K n gj
Q, PS r-4 i— 1 «— 1 i-4 ffl
CO ^ r-J
fa O
4-1
tfl
P*<
CO 1
CO
QJ ^ x-^j cn cn m
w """1
TU QJ
w • to
i a, s~. in o u*> pi
A; 6 fa P-. o oo
U 0) o CM CM CM S
CO H ^- 0
CC r-<
fa
cn
g
cn M
13 F 1
O -*-. -^ -^. M
H y-^J >J in O CM S
Q ^-* Q| vo ^ in o
o M cn
CJ Q) <
H O
Pi 3
W 4J PS r-(
>< w w eu
^ ^s| ,n| ^i| (^ .
C oo cn 00 ^ 00
DO) ... u >
o QJ *o r- co <
U O
C | OJ
•r4 I CO CTl CJ\ M
XI
^,
/•"N
tfl
Q)
H
O U*| O CM o O
i— i o CNI o cn i— i
o o o o o o
o o
•H C
4-1 QJ
O -r) ^*.
CD O S-S
r-l -H <^
O 4-<
CJ bJ
O> 00 00 00 O O
O O rH O t-J O
O O O O O O QJ
CO ^^
D OJ X!
'2^5
to
p-l
o o o o o o
r-» \D a\ CM r* o
r-t CM 0 rH 0 -*
^ ^H r-t ^ ^ ^ ^
o
•r-4
i-t 0>
Cfl N x—
CU *r-t n
cn -—
OOOOOO W 60
r-ir^ooaoc1^ o >
CMCMOOOO K <
CM CM CM CM CM CM S
S
0J-I OJ ^
111 W g
cu u a a
to M 5
.J S ED --
O
03
vO 00 O in vO O E-j
r*. CTN m \o CM o fc
cn •
vo r^ r^
^ Jt CO OO 1 — f^
10 r~
-------
o
CO 0)
\"t 4J
O CO
p, pd
to
w
ooooooooo
ooooooooo
^•^-icsi^-iovcoincsicsi
m vo i— >-icsicsifn
csicsicsicsicsiinrococn
O
M
H
O
O
a
o
u
O O O
in csi
oo
(1) x-,
4J B-S
O •—'
om
I OO CO CTi t— I
O
tfl
H
en
to
0)
O
O
S-i
PL4
4J 01
60 to
ooooooooo
oooooooo o
mooinmcsiooooi — oo
csirnromromrocncs]
4J
CO
a)
H
-a I
189
-------
13
0)
3
C
•H
4J
C
o
IB-
00
iH
i"H
01
tH
CO
H
w a
C en
•H -o
CO r-l
O fcC
,_} x
a)
4-1
CU
rH
U 4-1
., 1 U
4-J CO
CO r-l
p
M-l
U)
CD ra
TO
Pi
O
rT[ £i
*£J
?0
CO x^
o
M
H
H
Q
0 ^ ^
0 > E
pd . £•
E
. ; oy \ '
t>
1 ^
CO
CJ --N
0) rH
,-1 O
3^
**
4J
CO >^
•r~( r^
S 5^
&• •"•
B ri-l
(1) o
H --
60 C
C O
•I-t ••-(
rH 4J
a «
E o
CO O
tO (-J
CO
H
00
r— i
CO
o
VO
CO
rH
o
0
o
I— 1
ON
iH
0
o
m
^f1
<}•
3
^
m
o
CO
N E C
•r-l U 3 S-l
r-l r-l 3
;^ O PM
r-~. oo
1 1
m in
^
1 1^"\
VO
o
CO
r--
CN|
o
o
o
r— 1
OO
rH
O
O
00
CM
o-
o
CO
^
CO O
4-1 CJ
CO f£
CM vD
1 1
CM CM
rH i— 1
ON CO
ON rH
CM rH
0 0
m CM
co in
rH O
O 0
O 0
CM ON
CM CM
rH*" CN?
O O
0 0
r- o
CM m
0 O
rH in
vD CM
OO CO
CO t—
CO CO
VD in
CO N O CU
i-l rH O
co O CO
E f>. C
•H U V-l
r-l D
P-I te-t
OO
1
CM
rH
190
-------
x-s
0)
T3
3
i— i
O
C
8
"*— S
•
oo
rH
r-l
w
o
*s*
*T; , — s
2 e
o a
r^ ^_| £jf
Pi 0> -—•
W 4-1
fL< CO O
& w
r-4 CO
9 ^
Pi £3
H
8
a)
r-l
3 &
4J 0
CO r-<
O
•
'O
o
M
PM 0)
4J
4J CO
a) pi
r-l
r— 1
0)
P-l
s~-
£
^
r-l
v-'
r-J_
V_>
•H
r-l
4-1
f^
O
J>
} (
C)
'U
OJ
r-l
r^
f-\
rJU
r— 1
^.
jr-)lriaDinininr-ii>Jo>c^cocN
incoc^i. — it — ii — ii — CO cs) r-^ (^> Q f^> Q o O O C) O O O V-O O
c^inr-Hor^oNr--ico
O^^^^^^WOC^^Or^vDCN,-lr-^r;..CNrO
f
ir^roco cv^ooLr>ininlO
^tvD -, Cd 0
0 > 0 IS M-l
J>, >, (U 4-1
O M Tl r-l >
— _ - — -^^ — -> --.^
cd| -Cl| O| 13 1 <1J| M-l
191
-------
ret
Q
l
§
H
CO
>H
en
W
u
i
o
q
Qj
g
CO
EH x— ^
hJ 0
| — i QJ
CO 4-1
W en
ctf >N
EH
CO CIJ
W rH
H 0
%£ O
O
W •
cNiniooo^Dcnoo i— i &(
en (— i i— i co o oo \o pi J O T-H vtj 4-J
.
42
s-s
^
3
o
c
O
•H
4J
3
o
4-J
Ul
eu
H
^*, I-H CM cn ON fn rH 0s* ON o^
ONQOi-t ooooooo men ro
CMCN^J- ^inr^cN mm ^
ooo --HOOO oo o
inr-Joo m m
oooin ON^rHCM mm i— i
i— i m m ^oJrHen P-CN r-^-
T-H CM i— 1 CM CM r-4 rH
ooo oooo oo o
ooo oooo oo o
OOQCM Ln^or---*O i-Hv£> rH
mi/"i- rH 10 oo
_ _^ . _. —> ^ .
inmm mcn-^--* iom to
Iintn^o oo i— < , ^ rH rH rH ^, ~j i-H ^, 3
4J4J4J CJ LH 4J 4-1 4J CJMH4J O cj_j
3330) d_330J 30J
OOOPi OOOCri OPi
^1 ^1 ^1
oooai oootx; opi
iiii i i i i ii
rHCMencn
-------
O >J C
•H O O
CO O
•rl CO
r~- o
in vo
0) J3
4J ~\
to ja
SJ
to
Hi
as CN
oo r~- i^. o™i
CN m , to
o o >
>> cu
O U T3
cu
r*l U 4-J
M 3 n!
CO O 6
S J3 -rl
•ri JJ 4J
i-l -r-l 01
p, f^ fT1
0|
193
-------
H
W)
>H
OT
O
M
O
CM
H
c
o
4-1
CO
O CO J3
O, Pi .—I
W
O O O O
o o o o
LO r^* *j* o^
1-1 O O O
CM CM CM M
in
CO
oj
o
X
w
•a
c
w
I
^i
o
CO
PQ
M
•H
<
bl
vo vo co oo st ro r-i
in 0s C^ i—I m O vO
CM M CM CM r-l i-l O
o o o o o o o'
vo O CM
O m
CO >—I
O, /-
e f*
D o
H -^
M vo O vo
O M OO CM
CO CO CM CO
>J
V4l
Q|
vO
vo * CM m <± ro
r-l 6
Q
• 4-4
60 ^
m
r~- CM
OO CO
in i-<
co
0)
4-1
O
CO
•
CO
o
CM
vO
•
oo
4-1
CO >-
•rJ ,0
O O CO
in m r^ r~-
-l
PL)
XI 0)
60 4->
•H CO
0) Pi
o o o o
o o o o
-------
•a
0)
•a
3
i— i
o
c
o
U
C5
CM
i— i
01
(—1
,0
CO
H
c ^>
0 0
•H C
4J 01
0 -t-l ,—
01 U E^
r-l T-l -— -
r-< <4-J
0 >W
U W
C x-
O rJ C
•H O O
CO 4-1 4-1
CO O --.
•r-l CO ,0
B fn i-i
0)
4-1
3 CU -d
O 4J ^
•H Cfl ,0
4-1 OS r-l
CO
P-i
0)
o
S-< 01
CO N ^
O, -H 3.
CO N— '
w
U 00
JS >
<^ <3^
S
0
W rJ 0) /-v
P-i ai bo B
4J CO Q
rJ CO CO M
H
^*q
0
U /—.
0) O
rJ CN
3 CL P3
co O
en U *
01 Q C
(-1 -r-l
P-I
CU
rJ ^
3 ^ r-l
4-1 O J3
•2 fe IQ
O i— '
s --
0 ^
f^ 01 J3
4-1 -^
4-1 CO CO
0) 03 C
r-l O
t I 1 1
0) ^-'
P-I
4-1
CO
o>
H
C^ O^ O
...
O CM oo r^^
oo t — i Q**
1 1 II
vO v£> \D *>O
O O O O O O O
0 0 O 0 0 O O
OO CO O vO CM 1 — CO
(^ (y, ,_( ^ oo ^ ^
CM CM CO CO CM CM r-l
,
i-i
I
60
m
CM
II
0)
4-1
CO
J-i
(I)
1
CO
CO
01
•H
4-1
a
3
r-l
L4_|
14_|
01
CJ
C
o
i— i
0
U
^1
(-1
CO
a
•H
^i
•^
•
4J
r-l
3
CO
01
M
0
4J
CO
rJ
O
rQ
Cfl
tJ
*"O
T3
(U
4->
cfl
e
•r-l
4J
CO
w
195
-------
H
W 0)
O
M
H
i—< O *~* O
o o o o
o o o o
o o o o
oo co co a*.
o o o o
o o o o
m o •"£> r-*
0) U g-5
i—t -H *~s
i-4 V4-I
O "4-1
CJ}
<
O|
I I I I
n)| -Qj o|
196
-------
"A
,
§
H
CO
£/i
w
CJ
M
6
o
^J
§ ~
1H J-J
S 1)
O ,0
CJ .d
C/} P
H U
rJ CO
CO 4-J
W CJ
oS s
H 01
CO rH
H u
sr T
H 3
Q
§3
3
J
CN
CM
i— <
0)
CO
H
61
-S
O CO
•H s~ O
-U J-l O O O I-J
ro cu ,c o o o
rJ -w -^. 3
w u
J_J
}-<
CO
w 1
J^l en o> o>
U -H 5-?j CN CM CN
^x J r-- CM CM 2:
M £^ J_ . . . O
O — • Q| m r-* r- cj
O to co
UK <
W U Pi rH
PS -H M >
S \ ^, ^, S
D 0) CO CO CO CJ >
O CO ... <£
X r4 VO CN CM
cj U r- co co
C 1 eg
•H co wi m \*
OJ x--J . ^
)-i -H
^ r§
W OJ J-i O O O
ajxcux ooo •
P-i IS ^-H rH CM CM H
4-J
W CM CO -J-
H
U
CO
•a
0
ii_
o
CO
•*_,
, — ,
B
w
TJ
/-^
1
tfl
a
y-^
-
0
^
^__,
d
4J
CO
OJ
H
C ^
o !-« c;
•HOC
& G ~^~
^,_^^^ -HmXJ
r~* cy^ CP oo oo co g pi_, , — i
r^ rH p^ rH OO O ££) ^^.
oo m m ^ co CM
CM O rH O CN O
o o o o o o
C X
O 0
4-1 01
U '1-t S~
o o s*£
rH -r-l ^^
rH U-l
O 4-1
a w
•d" rH ^ CN rH in
co co CM r-- co oo
rH O O O rH O
o o o o o o
0 O O O O O W
COincMCTiCJ\rH U bo
cyivOCMOcNO
M y-*
3 > n
CM OO CM <]• \O r*. 4JOJ
r^co'^c^ovo *«-iri(^
CO fH CN CO 5 rH
S -—
TJ
O X-N
ti Ui
PW 0) J3
-XJOOOCOCMOO w-^,
x» r^ co
CO CM CO
°. *
r^ o
oooooo
oooooo
00 OO 00 00 00 00
1 1 I 1 1 1
oooooo
oooooo
1 1 •
oooooo
O «x> O CM O r^-
•d" CTi 00 in CM CO
CM rH CM
m m Ln
CO
-------
--^
31
aJ
0
H
O
<
&
O
M
C/3
cn
H
§
g
^
PM
a
o
M
H
Si
Q
W
W
Q
<3
fe
en
CM
T— i
cu
rH
CO
H
o
0
o
CO /-.
fn Cj
o
C 4-1
o ~-
•r4 ^
CO rH
CO ^
e
W
CO
c /-.
O p
CO --~
co x>
vO
•
vj-
0
m
60
C! /-v
•H M-l
•a o
CO CO
H-3 CO
C
C i-l
CO V-i
Vl 61
o
CM
o
o
(V
to B
CO CU
O H
o
CM
CM
^i
01
•H S
r< M-l
I-l O
co co
O
[5
O
rH
&J
o
0
0
m
cn
Pollutant
Source(s)
Primary cyclone and
^— ^
*"""•. J-l
*&£
S rQ
ei| rH
^-^
o
0
rH
CM
4J
C
CO
S
~~-
<
meal collection cyclone
and pellet cooler cyclon
^o
i
^j-
o
o
CM
O
o
CM
CM
O
£3
n
in
en
Primary cyclone and meal
collection cyclone
o
0
r--
rH
CM
^~
°<
v^f
•
^"
o -*
o' o'
rH in
in m
O CM
o o
dl
rH
rs
to
rH
•H
to
4J 0
o cn
SS rH
O O
o o
O 0
CM CM
Pellet collector cyclone
Pellet cooler cyclone
o o
o o
O 0
CO CO
CN CS
Q Q
%
CO •
(X CO
o a.
j£ o
CJ _C
,
eu c o
O P O
C 0) 4J >,
eu ex u
t-t M CO
cu co cu • B
M-I 13 ex eu 1-1
ai C C lj
Bj 3 -a o ex
O CU rH
c ex 4J o x:
•H 4-1 >-, 60
CO .r4 CJ 3
ors calculated from data
Weight Rate expressed a
r expressed as pounds em:
scharge through primary i
cyclone discharges throi
4J CO O -H p
O CO 4J T3 O
co eu o 4-1
M-l O CO CO O
Q fH CU d)
CO r4 O rH
C PH C! r4 rH
0 030
•r4 CO .H O O
CO -H CO CO
CO CO rH
•H PS *H rH CO
B 3 B r-< eu
13 PH W
-------
Table 124. ALFALFA DEHYDRATION PLANT EMISSION FACTORS
Emission Source
Primary cyclone (Plant C) —'
c/
Primary cyclone (Plant D)—
Primary cyclone (Plant E)—'
Primary cyclone (Plant F)—'
c/
Primary cyclone (Plant G) —
a/
Uncontrolled-
Emission Factors
(Ib/ton)
3.03
3.21, 5.72, 6.03
1.89, 2.12, 1.48, 1.37
1.34, 1.50
3.75, 2.28, 3.34 .
Average
Average
Uncontrolled
Emission Factor
(Ib/ton)
3.03
4.99
1.72
1.42
3.12
2.86
aj Emission factors are in pounds/ton of green chop.
derived from data in Reference 14.
t>/ All sources ducted to primary cyclone.
£/ Primary cyclone effluent was from dryer only.
Emission factors
199
-------
A comparison o£ available emission factor data, for the particulate
sources in the dehydrating process, is shown in Table 126. There are con-
siderable differences in the data from the different information sources.
The emission factors for the primary cyclone (which include other signifi-
cant sources in some cases) are highest for the data in Reference 13, and
show a range of 2.6-6.5 Ib/ton chops and an average of 4.65 Ib/ton chops.
However, emissions from the other sources are lower in Reference 13 than
Reference 15, especially from the meal collection cyclone. These variations
may be due to differences in control equipment, measurement techniques or
plant operating conditions. Data in Reference 13, for emissions from the
meal collector, were taken at the outlet of the secondary cyclone that is
in series with the primary cyclone which should help to reduce the emissions.
The emissions from the primary cyclone reported in References 13 and 14 also
include, in some cases, the effluents from other sources that are ducted to
the primary cyclone. This would add to the effluent from the primary cyclone,
but the total emissions may be less than they would be if the effluent from
other sources were allowed to vent to atmosphere.
Although the data reported in References 13 and 14 represent relatively
well controlled plants, the measurement techniques are significantly differ-
ent than those used in References 15 and 16. Measurements in References 13
and 14 were according to EPA Method 5 and included duct extensions for the
cyclone outlets. At least part of the sampling reported in Reference 15 was
performed right at the cyclone outlet which makes it difficult to obtain
accurate results. While differences in the emission factors may be partly
caused by the type of primary cyclone and the measurement techniques, it is
also known that emissions from these plants can vary widely due to quality
of the alfalfa (moisture and protein content) and operating conditions
(over drying or under drying), etc.).
Examination of the available data plus many plant visits and discussions
with plant operators and others knowledgeable in the field have lead to the
conclusion that the greatest portion of the dust emission from an alfalfa de-
hydrating plant comes from the drying operation (i.e., the primary cyclone).
The data in Table 126 show that the average emission factor for the primary
cyclone varies from 2.0 to 4.65 Ib/ton. The data reported in References 13
and 14 were obtained using EPA Method 5 procedures so these are probably
the most accurate values available. The average of these two values (2.86
and 4.65) indicate that the overall average would be 3=75 Ib/ton of green
chops. This is approximately equivalent to 15.0 Ib/ton of meal, which is
much lower than the emission factor of 60 Ib/ton of meal specified in
Reference 17. The Duprey factor was apparently based on data from Reference
15. These data were obtained prior to 1960, using techniques that are not
as accurate as the recent EPA procedures. It is therefore felt that the
emission factor of 15 Ib/ton of meal is more representative for the primary
cyclone and that the total plant emission factor probably does not exceed
20 Ib/ton of meal.
201
-------
Table 126. COMPARISON OF ALFALFA DEHYDRATION PLANT EMISSION
FACTOR DATA
(Ib/ton)*/
Reference 13
4.6V
sizV
4.4
6.5
Average 4o65
SECONDARY COOLING
Reference 15
1.25
0.72
PRIMARY
Reference 14
3.03V
4.99
1.72
1.42
3.12
Average 2.86
CYCLONE
CYCLONE
Reference 15 Reference 16
2.25 4.8V
3.25 1.9V
i.oJi/
o.sV
1.6V
2.7V
3.0^
Average 2.75 1.2
Average 2.0
MEAL COLLECTION CYCLONE(S)
Reference 13 Reference 15
0.65 2.25
12.0
Average 1 . 0
PELLET COOLER CYCLONE
Reference 13 Reference 15
Aver age 7 . 1
PELLET REGRIND
Reference 13 Reference 15
0.65
0.53-'
0.25
1.5
Average 0.8
2.0
0.5
a/ All emission data expressed as pounds per ton of green chops.
b7 Includes discharge from meal collector cyclone and pellet cooler cyclone.
£/ All sources ducted to primary cyclone.
d/ Includes discharge from meal collector cyclone.
e/ Sum of pellet collector and pellet cooler cyclone discharges.
202
-------
WHEAT MILLING
Flour and products made from flour have been used by man for centuries.
Flour milling has been transformed during the last 50 to 60 years from a
semi-agricultural operation into a complex industry. Milling processes have
undergone dramatic changes, as have also the transportation, distribution,
and usage of the product.
Modern flour mills are steel and concrete structures flanked by wheat
storage elevators. They draw wheat from wide regions, often from a quarter
of the nation, and the destination of the product is even wider in scope.
The Milling of Wheat
18/
The wheat milling process consists of five main parts. They are:—
1. Reception and storage of wheat,
2. Cleaning of the wheat,
3. Tempering or conditioning,
4. Milling of wheat into flour and into its by-products, and
5» Storage and/or shipment of finished product.
19 /
Figure 19 presents a simplified diagram of a flour mill.Operations
performed in each of these areas are discussed in the following sections.
Reception and Storage of Wheat - Wheat arrives at mill elevators by truck,
rail, barge or ship. Truck and rail shipments are unloaded at receiving
pits while marine conveying systems are used for barge or ship unloading.
Following unloading the grain is transferred by conveyors to the elevator
headhouse. The wheat received at a mill generally contains impurities and
foreign material such as sticks, stones, and bits of cloth or paper. These
are removed in a preliminary cleaning operation prior to storage of the
wheat. From the cleaning equipment, the wheat is conveyed to storage tanks.
Cleaning House - As grain is needed for milling, it is withdrawn from the
storage elevator and conveyed to the mill area. The first step is to send
the wheat through a cleaning operation prior to the actual milling. This
section of a mill is called the cleaning house. The techniques used in the
cleaning house must be refined in order to remove dust and smaller pieces
of foreign matter. The impurities usually differ from wheat by one or
several of the following characteristics: (1) size, (2) specific gravity,
203
-------
111!
I
P
60
n)
M-l
T)
OJ
0)
E
•r*
204
-------
(3) shape, (4) air resistance, and (5) inherently different material (e.g.,
metal, stone). Equipment used to clean the wheat utilizes one or more of
these differences to accomplish the cleaning.—'
While placement and sequence of equipment varies from mill to mill,
the general flow scheme shown in Figure 19 will be used for subsequent dis-
cussion. The wheat first enters a separator, where it passes through a
vibrating screen which removes bits of straw and other foreign matter, then
over a second screen through which drop small foreign materials like seeds.
Next, an aspirator lifts off lighter impurities in the wheat. The
stream of grain is directed across screens while air sucks off the dust and
lighter particles. The stream of wheat next passes over a magnetic separator
that pulls out iron and steel particles. The magnetic separator acts as a
safeguard against nuts, bolts, rivets, or other pieces of metal which may
break loose from machinery. Magnetic separators are used at many different
points in a mill, especially in the feed to any machine applying friction,
where the risk of damage or fire is greatest.
From the magnetic separator, the wheat enters a disc separator which
consists of discs revolving on a horizontal axis. The surface of the discs
are indented to catch individual grains of wheat but reject larger or
smaller material. The blades also act to push the wheat from one end of
the machine to the other. The revolving discs discharge the wheat into a
hopper, or into the continuing stream. The wheat is then directed through
another magnet to a stoner for removal of stones, sand, flints, and balls
of caked earth or mud which may be so nearly the same size as the wheat
grains that they cannot be sifted out. Both wet and dry stoners are used
for this purpose.—'
The wheat then moves into a scourer--a machine in which beaters attached
to a central shaft throw the wheat violently against a surrounding drum—
buffing each kernal and breaking off the beard. These machines remove a
great deal of dust and loose bran—skin adhering to the wheat grains.
Scourers may either be horizontal or upright, with or without brushes, and
adjusted for mild, medium or hard scouring. Air currents carry off the dust
and loosened particles of bran coating. Following the scouring step, the grain
is sent to a surge bin which acts as a storage/supply point between the clean-
ing house and the tempering bins or tanks.
Tempering or Conditioning - Modern milling practice utilizes conditioning or
tempering before the start of grinding. Tempering, as it is practiced in
the United States, involves adding water to grain to raise the moisture to
15% to 19% for hard wheats and 14.5% to 17% for soft wheats and allowing
the wheat to lie in tempering bins (with little or no temperature control)
for periods of 8 up to 72 hr. During this time, the water enters the bran
205
-------
and diffuses inward causing the bran to lose its friable characteristic and
to become leathery in texture. The percentage of moisture, length of soak-
ing time, and temperature are the three important factors in tempering, with
different requirements for soft, medium, and hard wheats. Usually, temper-
ing is done in successive steps since it is impractical to add more than a
few percent of water to wheat at one time.
When the moisture content is properly dispersed in the wheat for effi-
cient milling, the grain is passed over a magnet and then through an
Entoleter - Scourer - Aspirator as a final step in cleaning. Discs revolv-
ing at high speed in the scourer-aspirator hurl the wheat against finger-
like pins. The impact cracks any unsound kernels which are rejected. From
the Entoleter machines the wheat flows to a grinding bin or hopper from
which it is fed in a continuous metered stream into the mill itself.
Milling - The purpose of flour milling is to first separate the endosperm
from bran and germ in as large chunks as possible and then reduce the size
of the endosperm chunks to flour-sized particles through a series of milling
steps. The milling of wheat is done between pairs of rolls. These rolls,
which rotate in opposite directions at different rates of speed, do not
mill the wheat primarily by crushing. Rather, the reduction of the wheat
is by shearing forces which, because of the set of the rolls, are relatively
gentle.
The roller milling area is divided into two sections, the break section
and the reduction section. In the first, the kernel is broken open and the
endosperm is milled away. This system quite often involves four or more
sets of rolls each taking stock from the preceding one. After each break,
the mixture of free bran, free endosperm, free germ, and bran containing
adhering endosperm is sifted. The bran having endosperm still attached goes
to the next break roll, and the process is repeated until as much endosperm
has been separated from the bran as is possible.—'
The sifting system is a combination of sieving operation (plansifters)
and air aspiration (purifiers). A plansifter has flat sieves piled in tiers,
one above the other. The action of the sifter is rotary in a plane parallel
with the floor. As the sifter moves in about a 3.5-in. circle, the small-
sized particles spill through the sieve below while the oversized particles
travel across the sieve to a collecting trough and are removed. As many as
12 sieves can be piled one on top of the other and there are four separate
compartments in one plansifter.i^'
The flour and endosperm chunks (middlings) from the plansifter still
contain minute size bran particles which are removed by sending the product
through a purifier where air currents carry the bran away. A purifier is
essentially a long oscillating sieve, inclined downwards and becoming coarser
206
-------
from head to tail. Air currents pass upward through the sieve causing the
flour to stratify into endosperm chunks of different size. Aspirated mate-
rials go to millfeed.
The reduction system comprises two parts, roll mills and sifting machines=
The major difference from the break system is that the surface of the reduction
mills is smooth rather than grooved. The purpose of reduction rolls is to re-
duce endosperm middlings to flour size and facilitate the removal of the last
remaining particles of bran and germ.
Plansifters are used behind the reduction rolls and their purpose is to
divide the stock into coarse middlings, fine middlings, and flour. The coarse
middlings are returned to the coarse (or sizing) rolls, and the fine middlings
are returned to the fine roll, while the flour is removed from the milling
system.
Purifiers are often used behind the coarse reduction rolls. The purpose
in this case is size grading rather than purification, and purifiers are some-
times superior to plansifters for these separation requirements.
Flour stock is transported from machine to machine by gravity or air con-
veying. Older mills depend upon gravity with the wheat and flour being moved
to the top of the mill by bucket elevators and the flour flows by spouts to
the rolls and to the sifters. Bucket elevators have two serious disadvantages:
they are dusty, and they provide a place for insects to grow. Consequently,
flour mills are converting to the air conveying of flour and are abandoning
bucket elevators and gravity spouts.i§/
Storage and Shipment of Finished Product - Bulk handling of flour is gen-
erally done by pneumatic conveying systems. Bulk storage capacity varies
widely but most mills have bulk flour storage for from 2 to 4 days of produc-
tion. Special railroad cars and trucks are used to transport bulk flour.
Air Pollution Sources, Emission Rates, and Effluent Properties
The sources of air pollution in a flour mill complex can be grouped
into three main categories: (1) grain receiving and handling operations;
(2) grain cleaning (cleaning house); and (3) milling operations. Table 127
presents some of the more significant potential sources of air pollution in
each category.
Dust emission sources associated with grain receiving are similar to
those already discussed for grain elevators in the section on page 120.
Nearly all the operations associated with grain receiving and subsequent
transfer to storage are potential sources of dust. The grain unloading and
207
-------
cleaning steps are generally considered to be the main sources in this part
of the mill complex.
Grain dust, dirt, seeds, and chaff are all emitted from the equipment
used in the cleaning house. The separator, aspirator, and scouring equip-
ment are the principal sources of emissions in the cleaning house.
In the milling house, the product recovery systems associated with the
various pieces of milling equipment are potential sources of emission. Bran
and flour would be the principal materials emitted from these sources.
Flour shipping operations are not a significant dust source because
efforts are made to minimize loss of the valuable final product. Loading
of by-products can be a significant dust source depending upon the loading
procedures used at specific mills.
Data on rates of emissions from flour mill operations are not extensive
because only limited source testing has been conducted in flour mills. Avail-
able source test data for emissions from flour mill operations are summarized
in the following sections.
Table 127. POTENTIAL SOURCES OF AIR POLLUTANTS IN A
FLOUR MILL COMPLEX
I. Grain Receiving and Storage
1. Grain unloading
2. Elevator boots and heads
3. Garner and scale vents
4. Grain cleaner
5. Conveyor transfer points
II. Cleaning House
1. Separator
2. Aspirator
3. Disc separator
40 Scourer
III. Mill House
1. Break rolls
2. Purifiers
IV. By-Products
1. Hammermi11
V. Shipping
1. Bulk loading
a. Flour
b. By-products
2. Packing station
208
-------
Grain Receiving and Storage - Measured emissions from cyclone dust collector
systems serving railcar and truck unloading operations at one mill are sum-
marized in Table 82, p. 122. Tests were conducted during periods of peak
unloading activity in order to determine maximum emission rates.
Preliminary Grain Cleaning - Data on emissions from grain cleaning operations
performed at two storage elevators are summarized in Tables 96 and 97, pp. 143
and 144.
Grain Turning or Handling Operations - Every process in the storage elevator
involves turning (or moving) the grain. Turning includes the operations of
belt conveying, elevator transfer, turnhead operation, and bin dumping. Most
of these same conveyors and elevators are also used during unloading opera-
tions and at times a control system may be serving multiple operations.
Emission data for grain handling operations at two flour mills are presented
in Tables 101 and 103, pp. 149 and 153.
Cleaning House - All the equipment in a cleaning house can be a source of
dust emissions. The limited data available from one mill are presented in
3 /
Table 128.— In this mill, two cyclones are used to vent a Eureka Separator
and one cyclone vents the disc separator and all the conveyor belts and
legs.— EPA Method 5 source testing procedures were utilized to obtain the
data summarized in Table 128.
Mill House - Particulate emissions from the various machines used to mill
the wheat vary with type of equipment used and the physical properties of
the wheat. Table 129 presents some test data on grain loadings in the air
flowing in the ducts of flour mill suction systems. The data reported in
Table 129 were obtained as part of a study conducted in four flour mills to
establish the relative efficiencies of cyclone collection systems.
Reference 23 indicates that the dust generated by roller mills ranges
from 1.6 to 3.3 Ib/bu milled with an average of 2.1 Ib/bu milled.
Tables 130 and 131 present some estimated emission rates from control
2l7
systems on various sources in a flour mill complex.— The data in Tables
130 and 131 were calculated from measured air volumes and the quantity of
dust collected by the control device. These measured quantities, combined
with assumed efficiencies for the control devices, were used to calculate
the inlet and outlet grain loadings as well as quantity emitted from the
control device. Because accurate source testing procedures were not used,
the emission rates shown in these tables should only be used as general
indications of emission levels.
209
-------
U
1-4
(-1
s
g
3
i— i
fn
H
3
S
5
i-i
P4
CO
CO
O
CO
CO 4J
CU J3
CO
1
^^
3
,a
^
i-i
V •
0
i— i
X
1— 1
r-4
c>
'c
O
4-1
J3
i— 1
^^
r^
CO
O
o
•
o
x— '
ii
?-i
X3
rQ
1— 1
I-l
r-4
X^
4-1
U
CO
-^
H
W
r~-
CM
O
*
o
"o'l
i^-1!
^— N
s
m
o
CO
V.rf'
0
>
0
1
60
CU
0
h
3
O
CO
C
O
•H
CO
CO
•i-l
B
w
G
•I-l
4J
C
cu
>
to
cu
C
O
I-l
0
>,
0
CO
1
o
1— 1
X
m
1-1
0
m
o
o
0
in
1-1
^o
ro
0
•
0
0
I-l
c^
«t
1
o
1
n
o
4J
CO
M
CO
p<
cu
CO
CO
^
cu
M
3
W
CO
l
o
I-l
X
00
>
CO CU
•H >
O C!
o
60 O
C CO
•H T3 60
4-1 S Q)
C3 to i-J
CU
> M *a
o c
CU 4-1 CO
C! CO
O M co
i-l CO 4-1
O P. i-l
>, >
r~~ 4J
« -H
i-t T-I
4-1
T3 O
C CO
crt
vO
60
ft, C!
° -H
O i-l
t--. P.
o co
4-1 CO
T3 CU
CU ,fl
4-1 4-1
O
CU C
S-t i-l
J-l
O T3
O CU
CO
CU 3
4-1
3 CU
C W
•i-l CU
Bi>
3
S-l CO
CU CU
P. M
4-1 T3
. (U CU
3 CU 0
.n m o
--- M
,0 0 P.
i-l -H
,a in
O 3
vo a T3
o
C -u x
O M 4J
CO CU
TJ 13 g
cu a
CO CO •<
CO 4-1 PM
PQ CO W
tfl|^Q| CJ|
210
-------
Table 129. GRAIN LOADINGS IN DUCTS OF FLOUR MILL SUCTION SYSTEMS^'
22/
Mill
1
2
3
4
4
Suction
System
Smooth roll
Entoleter
Hammermill
All rolls
All rolls
Grain
On Mill
HRS
SRW & W
RYE
SRW & W
HRW
Grain Loading
in Air
to Collector^'
7.00
4.00
35.00
12.00
16.80
Dust in Air
Leaving Collector—'
0.045
0.175
0.182
0.053
0.036
&_l Grains per cubic foot, cyclones used as control device.
211
-------
CM i-l ,-H
C-l .—I
,—I
-------
4
4
rf
D
D
4
IV
<
j;
2
^
3
-4
O
H
G
4
3
rf
H
5
3
J
H
0
D
a
j
3
3
4
J
J
5
tj
4
0
3
3
1
a
~t
3
a
j
H
5
-t
-i
H
1
4
-1
•>
D
2
CU
to
BJ _
C £
0 ^
'H -Q
CO ^
1
eu
CO
Oi ,—.
C O
O CO
•iH -^
CO 61
Ji
CU
3
"o 'a
> 14H
I-l v^
•r-t
*£
r-4
O CU
4J -rl
C >
O CU
U Q
CU
o
u
o
en
oo oo
VO VO
rH rH
^ ^
CM CM
CO CO
0 O
0 O
0 0
0 O
vO VO
CU CU
(3 C
0 0
0 0
CJ CJ
a a
O 0
•H -i-l
1 1 JJ
o o
3 3
CO to
CU CU
01 to
3 3
O 0
0 O
4J 4J
to to
cu cu
rH rH
03 W
r~- ON
CO CM
rH 0
v£) O
ON CM
0 0
0 0
o o
VO vO
rH rH
CU CU
g g
O O
CJ CJ
C C
0 0
•H -rl
U 4-1
O O
3 3
CO CO
cu cu
CO CO
d 3
o o
4-1 4J
CO CO
CU CU
•§•§
CU 0)
l— 1 rH
0 O
CO O
CO vO
o o
4-1
to en
0 0
x> ao
t~~ i—
O 0
vO vO
f^"- I""*
0 0
0 0
o o
O 0
CM CM
rH rH
CU CU
a a
O 0
O O
CJ CJ
U U
o o
4J 4J
CO to
CU CU
l— 1 rH
rH rH
•iH -H
S S
4J 4J
co co
CU dl
"§ it
CU CU
rH rH
0 0
ON VO
vO ON
-------
DURUM WHEAT MILLING
Durum Milling Process
The method of milling durum is similar to the milling of wheat, but the
purpose is quite different. In the milling of wheat, flour is the desired
end product. In the milling of durum, middlings are wanted. Consequently,
in durum milling, the break system, where middlings are formed, is emphasized,
and the part of the reduction system where flour is formed is de-emphasized.
The processing of durum wheat into durum products consists of the follow-
ing steps:
1. Reception and storage of wheat
2. Cleaning of wheat
3. Tempering of wheat
4. Milling of durum wheat into products
5. Storage and/or shipment of finished product
Operations performed in the various parts of the mill are discussed in the
following sections.
Reception and Storage of Wheat - The operations involved in the reception
and storage of durum wheat are similar to those described for wheat in the
section on p. 203. Following unloading the grain is transferred to the
storage elevator by conveyors. Preliminary cleaning of the durum wheat is
usually performed prior to storage.
Cleaning House - Durum goes through normal cleaning house operations used
for wheat. The function and placement of equipment in a durum mill clean-
ing house is similar to that discussed for wheat.
Tempering or Conditioning - The tempering of durum uses the same equipment
as wheat but the holding times are shorter than for wheat. This is because
of the desire for middlings without flour production. Excessive times in
temper soften the endosperm making it easier to make flour. Short times
maintain the hard structure of endosperm which encourages the production
of endosperm chunks.
Milling House - The break system in a durum mill generally has at least five
breaks and provides for the very gradual reduction of the stock necessary
for good middlings production while still avoiding large amounts of break
flour.
214
-------
The rolls in a reduction system are used as sizing rolls only. None is
used to produce flour. They function the same as the sizing rolls in a flour
mill reducing the coarse middling to a uniform particle size. In a flour mill,
the sizing is done to produce a uniform product for further grinding on the
reduction rolls. In a durum mill, however, sizing is done to make a uniform
product for sale.
The sifting system of a durum mill differs from a flour mill by the
heavy reliance on purifiers. Actually, plansifters are used little. Rather
conventional sieves are much more in evidence. These are used to make rough
9fi/
separations ahead of the purifiers. —'
Storage and Shipment of Products - The methods used to transfer, store, and
ship the products of a durum mill are similar to those discussed for wheat
milling.
Air Pollution Sources, Bnission Rates, and Effluent Properties
The sources of air pollution in a durum mill parallel those of a flour
mill and can be grouped into three main categories: (1) grain receiving
and handling operations; (2) grain cleaning (cleaning house); and (3) milling
operations.
Dust emission sources associated with grain receiving are similar to
those already discussed for wheat on p. 207. Nearly all the operations
associated with grain receiving and subsequent transfer to storage are po-
tential sources of dust. The grain unloading and cleaning steps are gen-
erally considered to be the main sources in this part of the mill complex.
Grain dust, dirt, seeds, and chaff are all emitted from the equipment
used in the cleaning house. The separator, aspirator, and scouring equip-
ment are the principal sources of emissions in the cleaning house.
In the milling house, the product recovery systems associated with the
various pieces of milling equipment are potential sources of emission.
Shipping operations are not a major dust source because efforts are
made to minimize loss of the valuable final product. Loading of by-products
can be a significant dust source depending upon the loading procedures used
at specific mills.
Data on rates of emission from durum mill operations are limited. Since
the processing operations are similar to those of a flour mill, the rates of
emission are expected to be similar.
215
-------
CORN DRY MILLING
Corn is dry milled by two general systems--degerming or nondegerming.
The nondegerming system grinds corn, preferably a white dent, into a meal
with little, if any, removal of germ. Near the turn of the 20th Century,
the Beall corn degerminator was introduced to the dry corn milling industry.
The development of degerming equipment resulted in a milling system that re-
moves from the kernel practically all the hull, germ, and tip cap for the
production of corn grits, meal, flour, hominy feed, and oil. This system,
as used in the United States, will be used to discuss the various processes
in a corn dry milling plant.
The Dry Milling of Corn
The conventional degerming system involves the following steps after
receipt of the grain: ''
1. Dry cleaning and, if necessary, wet cleaning of the corn.
2. Tempering of the corn by controlled addition of moisture.
3. Separation of hull, germ, and tip cap from the endosperm in a
degermer.
4. Drying and cooling of product from degermer.
5. Multistep milling of degermer product through a series of roller
mills, sifters, aspirators, and purifiers.
6. Further drying of products, if necessary.
7. Processing of germ fraction for recovery of crude corn oil.
8. Packaging and shipping of products.
Figure 20 presents a general flow diagram of a corn dry milling facility.
The individual steps in the milling process are discussed in the following
sections.
Grain Receiving - Grain is transported to a mill by truck, rail or barge.
Truck and rail shipments are unloaded at receiving pits while marine con-
veying systems are used for barge unloading. Following unloading, the grain
is transferred by conveyors to a storage elevator. Preliminary cleaning of
the grain, using scalpers, etc., to remove gross impurities may be performed
prior to storage.
216
-------
o
z
5
Z-
c^
o
u
>
e£
Q
4J
d
co
^-4
Pu
00
•r-l
6
O
o
I
J-l
60
CO
•r4
T)
g
C
0)
o
CM
§>
•r-l
217
-------
Grain Cleaning - The cleaning step is one of the most important operations
in a dry corn mill. Ferrous metals are removed by a magnetic separator.
Dry cleaning devices such as milling separators, scourers, disc separators,
electrostatic separators, aspirators, vibrating screens, and destoners are
used to remove impurities. Surface dirt and spores of microorganisms can
best be removed by wet cleaning rather than dry. Conventional wet cleaning
equipment consists of a washing-destoning unit followed by a mechanical-type
dewatering unit, usually referred to as a whizzer.
Suspended solids are removed from the wash water effluent by a dewater-
ing screen, settling tank, or similar means and are added to the hominy feed.
The effluent usually is further processed in a waste treatment plant to re-
duce the BOD level before discharge from the mill.
Tempering - After cleaning,the corn is sent through a tempering or condition-
ing step. Normally, the moisture content of the corn is raised to about
21-25% rather than the 177= used for wheat milliag. 26»27/ This is done be-
cause the germ of the corn tends to be more friable than the germ of the
wheat and if it is too dry, it will break into small flour sized pieces dur-
ing degerming. If enough water is added, not only the bran is toughened but
so is the germ.
Degerming - Degerming follows the conditioning or tempering step. The Beall
degermer and corn huller are used in over 90% of the degerming mills in the
U.S. The Beall degermer is essentially an attrition device built in the form
of a cone mill. It consists of a cast-iron, cone-shaped rotor mounted on a
rotating, horizontal shaft in a conical cage. Part of the cage is fitted with
perforated screens and the remainder with plates having conical protrusions
on their inner surface. The cone has similar protrusions over most of its
surface. Also, the small or feed end of the cone has spiral corrugations to
move the corn forward; attached to the large end is a short cylinder corru-
gated in an opposing direction to retard the flow. The product leaves in
two streams. Through stock, normally about 60-75% of the degermer stock,
is discharged through the perforated screens and contains a major portion of
the released germ, hull, and degermer fines, as well as some of the grits.
Tail stock, in which large grits predominate, escapes through an opening in
an end plate facing the large end of the cone. A hinged gate with an ad-
justable weight restricts flow of this stock stream.
Entoleters, granulators, disc mills and roller mills are also used as
degermers.
Drying and Cooling of Degermer Stock - The moisture content of the degermer
product must be in the 15-18% range for proper milling. Rotary steam-tube
dryers with air drawn through the dryer to carry off the vaporized moisture
are often used to dry the degermer products.
218
-------
Coolers may be counter-flow or cross-flow rotary, vertical gravity
louver, or fluid bed. In the rotary types, lifting flights rotating inside
a horizontal shell shower material through an air stream and move the stock
towards the outlet. In the vertical cooler, solids flow by gravity down
through a column containing louvers for alternately introducing and withdraw-
ing cooling air. Air is drawn through the coolers either by a fan or a natural
draft tower. Temperature of the stock is lowered to 90°-100°F in the cooler
and the cooling step removes about 0.57» moisture.
Milling Operation - The milling section in a dry corn mill consists of sift-
ing, classifying, milling, purifying, aspirating and possible final drying
operations. After drying and cooling the degermer stock is sifted or classi-
fied by particle size and enters into the conventional milling system. The
feed to each pair of rolls consists of selected mill streams produced during
the steps of sifting, aspirating, roller milling and gravity table separating
in preceding stages of the process. Detailed data on the milling section are
presented in References 27 and 28.
For the production of specific products, various streams would be with-
drawn at appropriate points in the milling process. A number of process
streams often are blended to produce a specific product. The finished products
are stored temporarily in working bins, dried and cooled if necessary, and
rebolted before packaging or shipping in bulk.
Recovery of Crude Corn Oil - Oil is recovered from the germ fraction either
by mechanical screw presses or by a combination of screw presses and solvent
extraction.
Air Pollution Sources, Emission Rates and Effluent Properties
Table 132 presents some of the more significant potential sources of air
pollution in a dry corn mill. The dust, small corn particles, spillage, etc.,
are collected as part of the processing operation and saved for animal feed
in most corn mills. For this reason, control devices are considered as an
integral part of the process equipment, and, strictly speaking, the control
systems, rather than the milling equipment, are the emission sources. As is
the case in many of the operations in the grain and feed industry, it is usual
practice to duct several individual dust sources to a common control device.
Nearly all the operations associated with grain receiving and subsequent
transfer to storage are potential sources of emission. The grain unloading,
cleaning and drying steps are generally considered to be the main sources of
air pollutants in this part of the mill complex.
219
-------
Table 132. POTENTIAL SOURCES OF AIR POLLUTANTS IN A DRY CORN MILL
I. Grain Receiving, Cleaning, and
Storage
1. Grain unloading
2. Elevator leg vents
3. Garner and scale vents
4. Trippers, conveyor trans-
fer points
5. Grain cleaner
6. Grain dryer
II. Cleaning Section
1. Separator
2. Aspirator
3. Disc separator
4. Scourer
IV. Milling Section
1. Break rolls
2. Purifiers
3. Aspirators
4. Product dryers and
coolers
V. By-Products
1. Hammermill for extracted
flakes and hulls
VI. Shipping
1. Bulk loading
2. Packing station
III. Degerming Section
1. Degermer
2. Degermer product
dryers and cooler
3. Aspirators
220
-------
Grain dust, dirt, seeds and chaff are all emitted from the equipment
used in the cleaning section. The separator, aspirator, and scouring equip-
ment are the principal sources of emissions in the cleaning house.
In the degerming section of the mill, the product dryer and cooler ex-
haust streams may contain particulates. The aspiration system used to
separate the dried degermed product can also emit particulates.
In the milling section, the product recovery systems associated with
the various pieces of milling and aspiration equipment are potential sources
of emission. Bran and flour would be the principal materials emitted from
these sources.
Shipping operations involving the main products are not a major dust
source because efforts are made to minimize loss of the valuable final
product. Loading of by-products can be a significant dust source depending
on the loading procedures used at specific mills.
Limited data are available on the rates of emission from individual or
combined sources in dry corn mills. Table 133 presents data on measured
emission rates from selected sources controlled by fabric filter systems.
The data in Table 133, obtained with a UOP flue gas sampler, were reported
by one of the corn mills that submitted data in response to the emissions
inventory questionnaire. The mill has a daily production capacity of 17,500
bu and operates on a 24-hr day. A production rate of 730 bu/hr was used
to calculate the emission factors shown in Table 133.
Table 134 summarizes estimated emission rates from another dry corn
mill which responded to the emissions inventory questionnaire. The daily
production capacity of this mill was listed as 55,500 bu based on a 24-hr
day.
RYE MILLING
There is much more similarity between the milling of rye and the mill-
ing of wheat than there are differences. In either case, the object is to
produce a powdery or granular material from a cereal grain by careful pul-
verizing of the seed. In both instances, the purpose is to make the flour
substantially free of bran and germ. The same basic type of machinery is
employed.
Rye Milling Process
The milling of rye consists of the same five processing steps as for
wheat milling, namely;—
221
-------
C0|
r-l
i-l
M
S
is
f*J
K
O
CJ
>-l
g
S5
M
en
w
o
£D
o
en
Q
W
i-3
J
§
H
Z
O
U
S
0
PS
fe
en
W
£
2
!a
0
i i
en
en
Q
W
— y
P5
D
W
El
s
•
en
en
1-1
cu
1— 1
f\
pU
CO
H
r-l
O
4-J
0
CO
Pn
C
O
•rH
CO
CO
•r-l
e»
W
6
01
• 4J
CO
>
en
, |
O
r-l
4J
c
o
C_J
6
O
M
Pn
t3
cfl
O
rJ
4J
CO
a
!?
r-l
fK
OT
cfl
O
r-l
o
r-l
4J
CJ
0
u
T>
CU
CO
CO
CU
o
o
rH
CL
43
43
i— I
^
^— ^
r-l
42
43
J
X_^
S~~^
M-l
U
01
**1*^
r-l
M
•v^ ,
x*"s
.6
m
y
g
0)
4_)
CO
>
en
cu
CJ
$_i
3
O
en
in
r-l
O
0
•
O
VO
rH
r-l
CM
O
«
O
o
o
m
r~-
M
eu
4-1
r-l
>r4
M-4
U
•r-|
,j
43
CO
PM
CU
CO
3
O
XI
60
C
•r-l
c
eo
0
o
0
•
o
00
vO
•
0
I-l
0
I
o
o
0
vO
^o
%
•I—I
r-H
•H
14-4
U
•rH
(H
43
CO
fc
^*\
CN
^-^
CO
cu
r-l
43
CO
4J
>>
4-J
•H
CO
t-i
O
<)•
o
o
o
0
en
•
o
m
0
0
•
0
0
o
CN
r~
VH
CU
4-J
i-i
•rH
<4H
U
•H
rH
•8
PM
/— N
CM
<^S
CO
QJ
I-l
43
CO
4-1
>-,
4J
•H
>
«0
VJ
o
,
4-1
•H
>
CO
rH
O
r-H
0
o
0
•
o
<)•
r-H
•
O
en
O
O
•
O
0
o
>
T3
•r-l
I-l
4J
ci
cu
o
CM
o
O
O
o
CN
•
O
•*
o
o
»
0
o
o
CM
m
rH
CU
JJ
r-H
•H
(4-4
U
•rH
M
43
CO
PK
CO
rH
CU
•H
<4-l
•I-l
rH
(2
r-l
CU
CO
en
co
CO
O
CU
3
CM
s
4J
•r-l
CU
43
O
222
-------
-------
1. Receiving and storage of grain
2. Cleaning of the grain
3. Tempering
4. Milling of rye into flour and its by-products
5. Storage and/or shipment of finished product
Receiving and Storage - The grain receiving and storage operations at a rye
flour mill parallel those at a wheat flour mill.
Cleaning and Tempering - The flow through the cleaning and tempering portions
of a rye mill is essentially the same as the flow used in a wheat flour mill.
Conventional machinery, such as a receiving separator, disc machines,
Entoleter Scourer-Aspirators, and a stoner, can be used. However, because
it is more difficult to clean rye than wheat, this cleaning operation must
be more carefully controlled. The special problem with rye is occasioned
by the fact that rye grain, in contrast to wheat, varies more in size. It
is because of this that rye is graded for size as well as dockage and mois-
ture. Because of the size differences, in the cleaning house of a rye mill
gravity tables may be used to separate according to weight differences.
Pocket sizes in the disc machinery are also slightly different because the
shape of the rye kernel is different than the wheat kernel. The average rye
kernel is thinner and slightly longer than the average wheat kernel.
Rye Milling - After the rye mix has been cleaned, the proper amount of tem-
pering water added, and allowed to rest in the temper bins the length of
time desired, it is ready for milling.
In contrast to milling of wheat which is a process of gradual reduction
with purification and classification, rye milling is different in that it
does not employ gradual reduction. Both the break roller mills and reduction
roller mills in a rye mill are corrugated. Smooth rolls would flake the
stocks so that they either scalp off to tailings or to the next reduction
system and on out the tail of the mill to feed.
Following grinding, the screening systems employ plansifters just as
are found in a wheat flour mill. However, there is little evidence of
purifiers that are commonly used in wheat flour mills. This is the first
major difference between rye and wheat flour milling. The lack of purifiers
is important since it immediately indicates that there is not a premium on
the production of middlings on the break rolls of a rye mill..
This brings up a second and very basic difference between wheat flour
milling and rye flour milling. In wheat flour milling, the point is to make
224
-------
as much middlings and as little flour as possible on the break rolls. In
rye milling, one tries to make as much rye flour and as little middlings as
is possible on the break rolls. Essentially, this is done by applying more
pressure on the rolls although the type of surface on the break rolls—that
is the corrugations—also plays a part. As a consequence, there are more
break rolls in proportion to reduction rolls in a rye mill than in a wheat
flour mill.
Air Pollution Sources, Emission Rates and Effluent Properties
Air pollution sources in a rye flour mill parallel those in a wheat
flour mill. Table 135 presents some of the more significant potential
sources of air pollution in a rye flour mill. Data on emission rates from
the sources shown in Table 135 are meager. Estimates of emissions from a
few of the sources were provided by one mill that responded to the emissions
inventory questionnaire. Table 136 presents the estimates. The mill for
which the data are applicable has a production capacity of 2,500 hundred
weight (cwt) of flour per day and operated on a 24 hr/day basis. Using the
yield factor of 2.15 bu/cwt of flour, a processing rate of 224 bu/hr was
obtained for the mill. This processing rate was used to calculate the
emission factors shown in the last column of Table 136.
Table 135. POTENTIAL SOURCES OF AIR POLLUTANTS IN A RYE MILL COMPLEX
I. Grain Receiving and
Storage
1. Grain unloading
2. Elevator boots and
heads
3. Garner and scale
vents
4. Grain cleaner
5. Conveyor transfer
points
II. Cleaning House
1. Millerator
2. Aspirator
3. Disc separator
4. Entoleter scourer
aspirator
III. Mill House
1. Roller mills
2. Sifters
IV. By-Products
1. Hammermill
V. Shipping
1. Bulk loading
a. Flour
b. By-Products
2. Packing station
225
-------
,j
HJ
1 1
s
03
O
w
"
J
M
m
SOURCE!
CO
CD
O
1
P*
1
Pn
CO
w
H
^5
M
§
M
CO
CO
Q
W
t-t
^
^
H
CO
W
vO
c-o
, — j
0)
43
H
£-1 'U
O CO
O CO
(0 CU
[Vt £J
O
C J-i
O D
•r-l
CO 3
co ft
*rH *"*^.
6 43
W i-l
ON
in o
•-I O
o o
• •
0 O
J3
cu "7?
S u £
o -H r1
^ j> ^*^
^ CM
CO O
m cu
C
O r-<
•r4 0
CO H ^
•H C W
a o ^
w cj ^
w
^^
CM O
d o
'H
cu --^
o ja
O -H r-<
i i ^ v _j
oo
i-H r-l
CO
(1)
'O Q
CO
O i-l
hJ O
M X-N
CO C 4J
3 O M-l
Q CJ ^^
W
m
CM CO
CM O
13
O
i-H /^^
^ 10
CO CJ
CO -—
CJ
o o
VO O
vO vO
A
rH
^1
O CU
i-l 0
4J -H
C >
o cu
CJ Q
cu cu
c c
0 0
I-l 1-1
CJ CJ
S^ ^*>
CJ CJ
CU O
4J 4-J
CU
O
^(
3
O
CO
cu co
1-1 >-i
O -H
4J a
CJ CO
w <
vO
O
o
d
^
CJ CJ
0 0
CO CO
cu cu
1— 1 I— 1
i-4 i-l
•H •!-!
s a
226
-------
OAT MILLING
The processing of oats for hot cereals accounts for only about 10% of
the total bushels harvested each year. The milling of oats has the objec-
tive of producing two primary products; regular oats and quick oats. The
longer oats are separated from shorter oats in the processing and are used
to produce regular oats. The shorter oats are further reduced in size in
a cutting plant and are used to produce the quick oats.
The Milling of Oats
29 /
The milling process for oats consists of the following segments.—
1. Reception, storage and mixing of oats
2. Cleaning
3. Drying
4. Grading, hulling, and finishing
5. Cutting and flaking.
Figures 21, 22, and 23 present a simplified diagram of the oat milling
process. Operations performed in each part of this process are discussed
in the following sections.
Reception, Storage, and Mixing of Oats - Operations involved in the reception
and storage of oats parallel those used in wheat milling. The mixing of oats
for milling is also similar to the practice of blending of different grades
of wheat in the elevator operations.
Cleaning House - The initial step in the milling flow is the cleaning house.
The foreign materials removed during cleaning are sticks, corn, seeds, soy-
beans, barley, wheat, and dust. These contaminants usually become mixed with
the oats in the field and the various elevators through which the oats may
have passed prior to arrival at the processing mill.
The first machine in the cleaning flow usually is a closed circuit as-
pirator to remove dust, hulls, light trash and poor oats with no groat in-
side. Most cleaning house flows include a receiving separator which makes
a high volume separation by thickness, width and further aspiration.
227
-------
OATS FROM ELEVATOR
DUO ASPIRATOR
1/4 X 3/4
STICKS
DISC SEPARATOR
DISC SEPARATOR
AUTOMATIC SCALE
DUST
RECEIVING SEPARATOR
..-3/16X3/4
CORN
N9 MESH
WIDTH
GRADERS
DISC SEPARATOR
SEEDS
DOUBLE OATS
AND BARLEY
CLEANING
HOUSE
PAN
DRYER
COOLER
AIR
DRYING SYSTEM
CLEAN DRY OATS
Figure 21. Flow diagram for oat mill (cleaning house and drying system),
228
-------
GRADING FOR HULLING
CLEAN DK'Y OATS i
DISC
DISC
SHORT OAT SYSTEM
HULLER
I
ASPIRATOR
DISC
SEPARATOR [
WIDTH
GRADER
ASPIRATOR
DISC
GROATS
SEEDS
LARGE OAT SYSTEM
±
HULLER
ASPIRATOR
HULLS
HULLS
TO CUTTING PLANT TO FLAKING PLANT
Figure 22. Flow diagram for oat mill (grading, hulling and finishing).
229
-------
CUTTING PLANT
CUTTER
SHAKER
DISC
SEPARATOR
ASPIRATOR
FLOUR
FLAKING
\
HULLS
PLANT
STEAMER
FLAKING ROLLS
SHAKER
FEED
FLAKING
PLANT
STEAMER
SHAKER
FLAKING ROLLS
FEED
REGULAR FLAKES
(ROLLED OATS )
TO PACKING & SHIPPING
Figure 23. Flow diagram for oat mill (cutting and flaking plant).
230
-------
The oats then flow to a series of disc separators where sticks, seeds,
small oats, small wheat, barley and groats are removed. The main-stream
of grain then passes to a width grader. Though commonly called a width
grader, these units are really thickness graders as a slotted screen is used.
These short oats then go to a separate width grader. Normally most of
the barley and wheat pass over the slots. However, it is not necessary to
attempt removal of all contamination at this point since after hulling the
differential between the width of the wheat and barley as compared with the
groat will be greater so a width grading step in the mill will complete the
job. At times a thin slot at the head of the grader is necessary to remove
thin flat seeds, such as flax. The small oats are then recombined with the
large for drying.
Drying - The next major step in oat milling is drying. Most oats are dried
using pan driers, which are normally 10-12 ft in diameter and placed one
above the other in stacks of 7-14. Each pan is steam jacketed and open on
the top. The oats take at least 1 hr to gradually pass down the stack and
are moved from inside to outside by slowly moving sweeps. Oats then drop
from the outside to the inside of the pan below. Smaller mills use the
rotary steam tube dryer, but generally the flavor development is considered
to be lower than in the pan dryers. Some mills are now hulling oats with no
drying or conditioning, then drying the groats separately to develop the de-
sired toasted flavor.
Grading, Hulling, and Finishing - After drying and cooling, the oats are
ready for hulling. The primary purpose of the huller, as the name implies
is to separate the hulls from the groats; the hulling efficiency can be im-
proved by prior grading or sizing of the oats.
The impact huller, which is in almost universal use today, produces a
better yield and requires much less horsepower than the old stone huller.
The oats enter the center of a high speed rotor with fins which throw the
oats against a rubber liner fixed to the housing of the machine. This liner,
which reduces the breakage during impact, also assists in efficient separa-
tion of the hull from the groat. The huller produces a mixture of free
groats, free hulls, groat chips, fines, unhulled oats and some hulled barley.
The large and short hulled oats remain separated through the last
stages of milling which includes removal of the hulls and the final grading
steps to extract unhulled kernels, wheat, and barley.
The free hulls are "light" enough that aspirators remove them quite
effectively. However, small groats and chips can be lost with the hulls
so the air on the aspirators must be carefully adjusted particularly in the
short oat system.
231
-------
The sizing of the grain prior to hulling also assists the oat and groat
separation after hulling. The groats are sufficiently shorter than oats so that
a practical separation can be made by length using disc machines. However,
this separation is made less effective by some oats whose groats are as long
as the oat and by the huller damaging the tips of many oats that are not
hulled on the first pass. The oat stream separated in this step for return
hulling always contains some groats.
After most of the unhulled kernels have been separated, the groats are
sent to a width grader for additional barley removal. This separation has
become more difficult due to the increase in the size of the new oat varie-
ties and the contamination with thin barley.
Generally the final step in the large oat system is the separation of
the totally oat free groats. These groats are separated by cell machines
and will by-pass the cutting operation.
The cell machine consists of rectangular plates with indents similar
to a disc machine moving up a 30 degree incline. The groats drop onto the
moving plates near the center of the machine. The clean groats are carried
over the top and directed to storage prior to flaking. The rejects of the
cell machine, which will contain a few unhulled oats, are sent to the cutting
plant for processing into Quick Cooking Oat Flakes (1 min). Cell machines
for groat finishing are gradually being replaced by the more efficient gravity
tables.
Cutting and Flaking - Those groats which are to be processed in the cutting
plant for Quick Cooking Oat Flakes are usually not milled completely free of
oats and oat hulls. The cutting plant is designed to remove these contam-
inants.
The purpose of cutting is to convert the groats into uniform pieces, two
to four per groat, with a minimum of fine granules or flour. Cutting is
accomplished with rotary granulators. These consist of rotating round hole
perforated drums, through which the groats align themselves endwise and fall
against stationary knives that are arranged around the bottom and outside
surface of the drum.
The cutting fines (oat middlings) are then removed by a shaker equipped
with a 22-mesh tin mill screen, though various meshes are used in different
plants. The cutting flour is generally used as a high quality animal feed.
Next the cut groats are separated from the uncut groats, oats, and long
hulls by a cylinder separator or disc machine. The pickups of the disc are
aspirated by a closed circuit or multilouver type machine which removes loose
hulls or slivers that may be present in the cut groats.
232
-------
The cut material is now ready for the flaking plant. Conditioning the
groats for flaking is accomplished by steaming them with live steam at atmo-
spheric pressure just prior to flaking. The steaming softens the groats
and permits flaking with a minimum of breakage. Also enzyme systems which
could cause rancidity and undesirable flavors in oatmeal are inactivated.
The steamed groats pass directly into the rolls from the steamer. The
cut groats are rolled into relatively thick flakes for quick cooking oatmeal.
The uncut groats are flaked about 50% thicker. The rolls are adjusted to
produce flakes of uniform quality, which is determined by thickness or den-
sity measurement of the flakes.
The shakers under the rolls remove fines produced in the flaking process.
Also, over-cooked pieces which are generally agglomerates of several flakes,
are scalped off. The flakes also generally pass through a multilouver or
terminal velocity type cooler. Hull slivers are removed with the cooling air.
The moisture content and temperature are quickly reduced to insure acceptable
shelf life.
The cooled flakes are then conveyed to the packaging system. Since
quick flakes are easily broken, the flaking system is often located above
and near the packaging equipment. Conveying equipment causing a minimum of
abrasion is used.
Because of a wide density variation in the flakes, packaging must in-
clude weighing the contents of each container. The poor flowing characteris-
tics make the filling somewhat difficult. Generally a plunger is used to
gently compress the flakes into each package.
Air Pollution Sources, Emission Rates, and Effluent Properties
The operations and equipment in an oat mill that are main sources of air
pollutants are shown in Table 137. Dust emission sources associated with
grain receiving and storage are essentially the same as those in other grain
elevator operations. The handling of oats is reported to be dustier than
many other grains but no data have been located that would allow a quantita-
tive comparison.
The separation requirements in an oat mill, unlike wheat milling, necessi-
tates extensive use of aspirators and it is expected that these would represent
a significant portion of the potential emissions from the oat milling process.
233
-------
Table 137. POTENTIAL SOURCES OF AIR POLLUTANTS IN AN OAT MILL
I. Receiving, Storage and Mixing
1. Grain unloading
2. Elevator boots and heads
3. Garner and scale
4. Transfer points
II. Cleaning
1. Duo aspirator
2. Receiving separator
3. Disc separators
III. Drying
1. Pan dryer
2. Cooler
IV. Grading, Hulling, and Finishing
1. Disc separators
2. Hullers and aspirators
3. Cell machines or gravity
tables
V. Cutting and Flaking
1. Shaker
2. Disc separator
3. Aspirators
4. Steamers
5. Groat conditioners
6. Shakers
7. Coolers
VI. Packing and Shipping
1. Packing
2. Bulk loading
VII. By-Product System
1. Hammermi11s
Oat milling also includes coolers in the drying and flaking operations.
Cooling is accomplished by direct contact with a stream of forced air which
could also represent a significant source of dust emissions.
The pan dryer in the dryer section and the steamer in the flaking sec-
tion may not be significant sources of dust emission but they may be potential
sources of odors.
In some oat mills, the hulls are ground in hammermills and this could
also represent a significant source of emissions.
Because nearly all the grain dust and by-products collected in an oat
mill are used in animal feed or other products, control devices are gen-
erally considered as an integral part of the process equipment. Therefore,
the control devices actually represent the emission sources. Limited data
are available on emissions from the various operations in oat mills.
234
-------
Table 138 summarizes measured emission rates reported by one mill that re-
sponded to the emission inventory questionnaire. The mill for which the data
are applicable has a production capacity of 1,250 bu/hr. The emission factors
shown in the last column of Table 138 were calculated using this production
rate.
RICE MILLING
Nearly all rice consumed as food undergoes some type of milling opera-
tion during its preparation. Rice milling differs considerably from the mill-
ing of other grains because the preferred form of rice is the whole grain
rather than a flour or meal. Pulverized forms of rice are used to a limited
extent in sauces and the like. Fairly large amounts of broken kernels and
small pieces are sold for manufacturing purposes, as for brewing and the manu-
facture of breakfast cereals or snacks. However, the demand for whole cereal
rice far exceeds that for smaller piece sizes, and the market value of the
former is correspondingly greater.
Rice Milling Process
Both conventional and parboil rice mills are used in the U.S. with the
former accounting for about 85% of the national rice crop. There are three
distinct stages in each of these mills: (1) rough rice receiving, cleaning,
drying and storage; (2) milling; and (3) milled rice and by-product bagging,
packaging, and shipping.
Rough Rice Receiving, Cleaning, Drying, and Storage - The rough rice receiv-
ing, cleaning, drying, and storage operations are the same for both types of
rice mills. Grain is received primarily by truck and rail at rice mills.
Rough rice is delivered to the mill containing various kinds of debris, such
as straw, loose hulls, bran, weed seeds, pebbles, and granules of dirt. The
rough rice is first cleaned using combinations of scalpers, screens, and
aspiration. If the rice was not purchased from a commercial dryer, the rice
is then sent to drying equipment to reduce moisture content to a level
suitable for storage. Since rice is marketed as a whole grain product, it
is important that the grains not be fractured or otherwise damaged before or
during the drying process. Large column-type, continuous-flow dryers using
heated air as well as batch-type units have been widely used.
Following drying of the grain, the rice is transported by conveyors and
elevators to storage facilities. In some rice mills, the grain is given an
additional cleaning when it is transferred from storage to the milling section
of the plant. Figure 24 presents a flow diagram for a rough rice receiving
department in a rice mill while Figure 25 shows the general sequence of
operations in a combined white rice and parboil plant.
235
-------
Table 138. MEASURED EMISSION RATES FROM CONTROLLED SOURCES
IN AN OAT MILL COMPLEX
(UOP Flue Gas Sampler Used for Measurements)
Emission From
Source
I. Storage Elevator
1. Basement belts
and bin floor
belts
2. Bin floor trans-
fer belts
3. Basement and bin
floor belts
4. Conveyor belt
II. Mill Complex
Cleaning house
equipment
Cleaning house
equipment
Mill equipment
Mill equipment
Mill equipment
Cutting plant
Cutting plant
Gravity tables
Gravity tables
Brush machines
Drying and cooling
equipment
Drying and cooling
equipment
Drying and cooling
equipment
Oat rolls and
screeners
Cooling towers
Cooling towers
Screenings system
Hull grinder
Hull grinder
Hull grinder
Control
Device
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Fabric filter
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Gas Flow
(cfm)
15,000
15,000
15,000
1,000
7,500
7,200
4,000
4,000
3,800
5,600
3,000
6,600
7,800
6,800
7,500
7,500
7,500
4,800
6,500
6,800
1,800
2,000
2,600
2,400
Control
(gr/ft3)
0.056
0.035
0.056
0.013
0.018
0.018
0.026
0.026
0.012
0.025
0.017
_
-
0.036
0.04
0.06
0.08
0.007
0.026
0.083
0.002
0.11
0.13
Device
(Ib/hr)
7.2
4.5
7.2
0.11
1.16
1.11
0.89
0.86
0.39
1.2
0.44
_
-
2.10
2.57
3.73
5.08
0.29
1.45
4.84
0.37
0.032
2.36
2.66
Emission Factor
(Ib/bu processed)
0.0058
0.0036
0.0058
0.00009
0.0009
0.0009
0.0007
0.0007
0.0003
0.001
0.0004
0.0017
0.002
0.003
0.0041
0.0002
0.001
0.004
0.0003
0.000026
0.0019
0.002
236
-------
Rough-Rice Receipts
(Truck and Rail)
r
I 1
d
(Scales)
Weigh, Sample,
Grade, and
Receive Binning
Instructions
Note:
Dotted Lines Show
Alternative Flow
of Rice
(Cleaner)
Foreign Material
is Removed
Foreign
Material
|
(Bin Storage)
Rice is Held
for Processing
1
(Dryer)
Excess Moisture
is Removed
from Grain
Moisture
L
(Bin Storage)
Rice is Held
Until Sent to
Milling Dept.
r
*
i
to Milling Dept.
Figure 24. Flow diagram for rough rice receiving section of a rice mill.
237
-------
c.
(
1
a
CO
1
^
1
a
<;
C
i
•+-
C
a.
'o
0
'°*
^ 5
!
aj
u
01
>
o
O
c e z
3 • •- ~
; 2
r^ <
0
t— Dl
c
'•
1 * I
? ,,
3 > -0 C
[ " " •«" "^ S"
1} 1
1 — ^
m ^ -5
d 1 £l
* E
O
'1
c |
J5 "~*<5J
"5
X
i
"3
X
c
- (
^ .- 'I
"5 ~4» 'i
"^ iyi * c
a . 5 § 1
fc * ^^'^ » "° »X
"o> o •- ,b " 2 "5
D 4) 0) Q. **• D
D
C
o
CO
f
1
C "D
o o qj ^
_,_ p
I „ p
T N £- o
"^ —
Id
S
QQ | i
1 c *"*
2 8
o <•? x
M-- s -17
'o. -c u
| < ^ ^
i |
"o
1 IS
.-? § 0
le -
" s
"P _ -5 f ^
6 _§
5 .9
5 P
L8.
c J!
E £
cO O c
"S '2 u
— O 5
-£
-------
Milling Section
White Rice Milling - The milling of rough rice to produce white rice is the
major milling operation conducted at U.S. rice mills. Cleaned rice is first
transported to a shelling device where the rice is dehulled. Stone and
rubber shellers are used for this operation. The hulls that are produced
are relatively light and are readily removed from the shelled grains when the
mixture is aspirated. The hulls are collected by passing the aspiration air
through a product recovery device, usually a cyclone.
Brown rice produced in the shelling process contains some unshelled rice
grains which must be separated. This operation is performed in a device known
as a paddy separator, which consists of flat cars divided into three tiers of
irregular compartments. The cars are tilted in such a way that when they are
rapidly shuttled, the lighter, bulkier, rough rice (commonly called paddy) is
concentrated at the raised side, while the heavier brown rice migrates to the
lower opposite side. The process is continuous, and streams of brown and rough
rice are removed simultaneously. The unshelled paddy is then fed into another
pair of shellers set closer together than the first set, and the above process
of shelling, aspiration, and separation is repeated.
From the paddy machines, the rice is conveyed to the hullers or milling
machines which scour off the outer bran coats and germ from the rice kernels.
Milling may be accomplished in one or two "breaks" that is, by a single pass
through a mill or by consecutive passages through two mills, depending on
plant practice. In some plants, as many as four breaks have been used.
After the rice is milled, it consists of almost white whole kernels mixed
with broken kernels of different sizes. It is now ready for the brush, a
device for removing the white inner bran layers and the proteinaceous aleurone
layer. The brush is essentially a large vertical stationary cylindrical screen
inside of which rotates a drum to which is attached overlapping leather flaps.
The rice enters at the top of the machine and, as it progresses toward the
bottom, is rubbed against the screen by the leather flaps. The white flour
mixture of fine bran and aleurone layer removed by abrasive action is forced
through the screen and is collected and sacked. The collected "polishings"
is usually sold as a by-product for animal feed.
At this stage the rice kernel consists of the white, starchy endosperm,
together with fragments of the aleurone layer. Rice may be sold in this form
as polished uncoated rice or it may be conveyed to machines known as trumbels,
in which it is coated with talc and glucose. This inert, harmless coating is
used to give the rice a gloss.
Even with care, some of the kernels are broken during milling. A series
of machines or classifiers separate the different size kernels. The whole
239
-------
and three-quarter kernels are screened into a fraction and designated as
"head" rice; the one-third to three-quarter rice grains are classed as
"second-heads." The one-quarter to one-third length of grains are known as
"screenings;" and the still smaller fragments are termed "brewers" since
they form a useful brewing adjunct.
Parboiled Rice - A limited number of mills in the United States produce par-
boiled rice. In some cases mills produce both white and parboiled rice.
The mills are similar in that all involve soaking rough rice following clean-
ing, steaming, drying, and milling. Pressure vessels are utilized for the
steaming step and steam tube dryers are employed to dry the rice to 11-1370
moisture. Following the drying step, the rice is milled in conventional
equipment to remove hull, bran, and germ. The better head yields obtained
in the milling of parboiled rice than in the milling of raw rice defrays to
a considerable degree the cost of parboiling so that parboiled rice sells
for little more than white rice.
Air Pollution Sources, Emission Rates, and Effluent Properties
In rice mills air pollutants result primarily from: (1) grain receiv-
ing, cleaning, and storage operations; and (2) rice milling equipment, and
by-product processing and loading operations. Table 139 presents some of
the more significant potential sources of air pollution in rice mills.
Emission sources associated with the grain receiving, cleaning, and
storage operations are similar to those involved with all grain processing.
For those mills that dry rice, the rice dryers present a very troublesome
source of emissions. Combine harvested rice is cut at a relatively high
moisture content and must be dried before it can be stored. Since rice is
marketed as a whole grain product, it is important that grains not be
fractured or otherwise damaged before or during the drying process. Large
column-type, continuous-flow dryers are widely used for rice drying. It
usually requires two or more passes through the dryers to bring the moisture
content down to 12.0 to 13.5% which is usually considered satisfactory for
safe storage. Air volumes of 120 cfm/bu of rice are commonly used. Rice
OQ 317
drying is reported to generate a considerable amount of dust.''
Preliminary cleaning of rice is sometimes done prior to drying. This
preliminary cleaning can produce a significant reduction in dust emissions
during the drying step.
Finished rice, marketed as U.S. No. 1 grade, contains no dust. To
achieve this grade, aspiration is used extensively in rice mills to remove
dust as it is generated in the various milling steps (i.e., dust is not
conveyed from one machine to another). As a result, all machinery in a rice
240
-------
Table 139. POTENTIAL SOURCES OF AIR POLLUTANTS IN RICE MILLS
I. Grain Receiving, Cleaning, and
Storage
1. Grain unloading
2. Elevator leg vents
3. Garner and scale vents
4. Trippers, conveyor transfer
points
5. Grain cleaners
6. Grain dryer
II. Cleaning House
1. Scalpers
2. Screens
3. Disc separators
III. Mill House
1. Shellers
2. Paddy separator
3. Milling machines
(hullers)
4. Brushes
5. Hull grinders
IV. Load-Out
1. Hull loading
mill is a pollution source to some extent. The most significant sources of
dust are the scalpers, screens, sieves, disc separators, and shellers in-
volved in the cleaning and handling of rough rice. The milling machines,
pearlers, and brushes create a bran dust; however, this is collected rather
carefully because of its value as a by-product.
Finished rice is free of dust, and its handling poses no problem in air
pollution. However, handling of the by-product hulls, especially loading,
generates considerable dust.
Table 140 presents actual measurements of emission rates from some
operations in a rice mill located in the State of California. All testing
was conducted with the mill running at normal operation. Testing was con-
ducted in accordance with the San Francisco Bay Air Pollution Control District
Regulation 2 procedure.
In addition to these tests, visual observations were also made at the
truck and railcar unloading facilities. All of these facilities are "under
cover." Particulate losses from these facilities were observed to be mini-
mal and were not judged to contribute in any gross amount to overall losses
from the mill to atmosphere, even under the high wind conditions which existed
during a majority of the observation periods.
241
-------
Table 140. PARTICULATE EMISSIONS FROM SELECTED OPERATIONS IN A
RICE MILL
Test Flow Loading Loss
No. Location (SCFM-dry) (Gr/SCF-dry) (Lb/Hr)
1 Hull conveyor cyclone 22,700 0.0529 10.3
2 Hull conveyor cyclone 22,700 0.0625 12.2
3 Bran airlift (75 hp) 15,400 0.0037 0.5
4 Bran airlift (75 hp) 15,300 0.0063 0.8
5 Dustex filter outlet!/ 81,000 0.0450 31.3
6 Dustex filter outlet^/ 81,000 0.0581 40.3
7 Dustex filter outlet!/ 81,000 0.0486 33.8
8 Bran airlift (60 hp) 19,100 0.0012 0.2
9 Bran airlift (60 hp) 19,300 0.0003 0.04
10 Brewers airlift 2,500 0.0003 0.01
11 Brewers airlift 2,500 0.0026 0.05
£/ Integrated system for cleaning and milling section of complex.
COMMERCIAL RICE DRYING
A distinctive feature of the rice harvesting, marketing, processing
cycle is the use of commercial rice drying and storage facilities. Commer-
cial rice dryers operate as a distinct industry in the rice growing areas
of the United States. Commercial rice dryers provide drying and storage
services for rough rice on a custom basis and are either private or coopera-
tive in financial organization.
Commercial Rice Drying Facilities
Rice is normally harvested with moisture levels ranging from 18-26%.
Since it cannot be safely held for long periods at these levels, the moisture
content is generally reduced to about 12-14% before storing. At commercial
dryers, this is accomplished artificially by use of aeration and heat. Al-
though much of the moisture can be removed by aeration alone, use of heated
air greatly reduces drying time, making it possible to handle larger volumes
of rice in shorter periods.
A commercial rice drying facility has four basic operations: receiving,
drying, storing, and shipping. A rice drying facility, therefore, operates
242
-------
in essentially the same manner as a grain elevator with emphasis placed on
the drying operation. Figure 26 shows the flow pattern at a rice drying
installation. The receiving operations parallel those described for grain
elevators in the section on Grain Elevators (Grain Marketing Operations) on
p. 110. Trucks generally transport harvested rice (green rice) to dryers.
Methods of receiving at dryers vary, depending upon such factors as location,
age, and size of plant. The most common procedure is to weigh, sample, and
grade at the scale house. After weighing, the truck is directed to the dump
pit where it is unloaded mechanically by hydraulic hoist, dragboard, or other
means.
Green rice is usually conveyed from the receiving pit to the receiving
leg by auger or belt conveyor. It is then elevated to the top of the head-
house where it can be diverted either to the dryer or scalper-type cleaners,
or dropped onto a gallery conveyor and moved to storage tanks to await drying.
Relatively clean, properly aerated green rice may be held in storage several
days before or during the drying process.
Green rice is normally dried gently several times to avoid cracking and
checking the kernels. Large column-type, continuous-flow dryers using heated
air are widely used for rice drying. Aeration is also used as a supplemental
drying method at some facilities. On each pass through the dryer column, the
forced heated air evaporates the moisture, which gradually migrates to the
surface of the kernels during the 6-24 hr between passes.
After the moisture content is reduced to about 12-1470, the rice is
ready for storage. Both upright and flat storage is used for rice with up-
right facilities being the most common on a capacity basis.
Rice is loaded out by several methods, depending mainly upon type of
storage facility and mode of shipment used. Gravity is generally used when
loading out for truck shipment from upright storage. Various types of equip-
ment are used to load rice directly from flat storage into trucks. In some
situations, part or all of the rice in flat storage is moved to upright
storage before loading out. This better utilizes labor, increases loadout
rate, allows several trucks to load out at once, or allows weighing through
a dump scale before loading out into railcars. Rough rice is shipped domesti-
cally almost entirely by truck or rail.
Air Pollution Sources, Emission Rates, and Effluent Properties
At a rice drying facility, emission of air pollutants result from the
rice handling and drying operations. Receiving pits, conveyors, elevator
legs, transfer points and vents are all potential sources of emission of
grain dust, chaff, and dust. The cleaning step, if accomplished by
243
-------
Rough-Rice Receipts
(Truck)
1
(Scales)
Weigh, Sample,
Grade
Note:
Dotted Lines Show
Alternative Flow
of Rice
r
(Cleaner)
Foreign Material
is Removed
Foreign
Material
|
1
J_
(Bin Storage)
Rice is Held
for Drying
|
1
*
(Dryer)
Excess Moisture
is Removed
from Grain
Moisture
(Bin Storage)
Rice is Held
Until Shipment
I
Figure 26. Flow diagram for rice drying facility.
244
-------
aspiration, is a major source of dust. The grain dryer is the other major
emission source. Rice Loading operations can also be a dust source.
Neither measured nor estimated emission rates for any of the operations
at a rice drying facility were reported by companies responding to the
emissions inventory questionnaire.
SOYBEAN PROCESSING
The soybean has risen from the bottom of the U.S. agricultural crop
ladder over the past 40 years to its position today of being number two.
Only corn is still ahead of the soybean in cash value to the American farmer.
Behind this unprecedented growth of an agricultural crop were two attributes
of the soybean seed: a high content of excellent protein and a moderate con-
tent of oil useful for edible and industrial purposes. Exploitation of the
attributes of the soybean resulted in the development of a worldwide mar-
keting and processing technology covering the seeds and its two main products.
Today, soybean and its products are the most exported agricultural goods
reaching, from the U.S. alone, the billion dollar level in recent years.
So important has the soybean become to the American scene that it receives
32/
the active attention of almost every facet of private and public agribusiness.—
Soybean Plant Operations
Each bushel (60 Ib) of soybeans yields ~ 11 Ib of oil and 47 Ib of soy-
bean meal with 2 Ib normally lost in processing. Oil is extracted from the
beans by (1) expeller or rotary screw pressing, (2) batch type hydraulic
pressing, and (3) solvent extraction. Since most U.S. soybeans are processed
by the solvent method, using hexane as the solvent in a continuous extraction
process, subsequent discussion will be focused on this process.
Figure 27 presents a schematic of the overall features of a soybean
processing plant using solvent extraction. Not all plants produce the com-
plete spectrum of products depicted in Figure 27. A majority of the plants
produce only the soybean meal and soybean oil. The industry generally
offers soybean meal as either 44 or 49% protein base, with few variations
in between.
Soybeans are shipped to the processing facility by rail, truck or barge.
Upon arrival at the plant, the beans are dumped into hoppers at unloading
stations and conveyed to the storage facility. Prior to entering the process-
ing portion of the plant, the beans are cleaned and dried. Since the process
requires beans between 10.5 and 1170 moisture, and beans from the field con-
tain 10 to 1670 moisture, most, if not all plants, utilize grain dryers to re-
duce the moisture content to the requisite level.
245
-------
c
CO
60
C
•H
CO
UJ
0)
O
O
M
ft
d
cfl
0)
O
05
14-1
O
I
M
t>o
§
!-l
M-l
-------
After the cleaning and drying steps, the beans are conveying to the flake
preparation portion of the plant. Flake preparation consists of cracking,
dehulling, and conditioning. The beans are first passed through cracking
mills or rolls where each bean is broken into four to eight parts. The hulls
and meat are then separated in dehulling equipment which may utilize a com-
bination of screens, aspiration, and gravity tables. The hulls, which were
separated from the meat, are collected by a cyclone and/or fabric filters,
and then sent through a grinding step prior to being conveyed to storage.
Some plants toast the hulls prior to grinding. The meat is transferred from
the dehulling-separation equipment to the conditioning equipment. The condi-
tioner is typically a rotary steam tube unit that heats the meat to 160-170°F.
Proper conditioning yields bean pieces which are sufficiently plastic that
good flakes can be formed.
From the conditioning equipment, the meat is conveyed to the flaking
rolls. Properly prepared flakes are essential for consistently good extrac-
tion. Normally, soybeans are flaked to 0.01 to 0.012 in. in thickness before
extraction.
Following the flaking operation, the beans enter the solvent extraction
part of the plant. There are several different types of extractors. In one
of the common types (Hansa-Muhle System, Bollman System and French Oil Mill
System) the bean flakes, in sieve baskets attached to an endless chain con-
stantly moving in bucket elevator fashion, are soaked with sprayed solvent
which drains and is recirculated.
The "Rotocel" unit (Blaw-Know Company) carries the flakes in compartments
horizontally around a central axis as they are sprayed with solvent.
Another type of extractor (Hildebrandt System) is a U-tube shaped tower
through which the flakes move by screw conveyor with the solvent circulating
in a counter current direction.
The Allis Chalmer System and Anderson System consist of a vertical column,
similar in size to the sieve basket type, but containing slotted horizontal
plates spaced several feet apart. The flakes fall downward from one plate
to another after being carried around the circumference of each plate by a
scraper arm. Solvent is introduced at the bottom and the miscella (about 2070
oil and 807o solvent) flows out at the top.
Extractors are operated at about 125°F and at nearly atmospheric pres-
sures. Bean flake and oil-extracted-meal seals at the extractors may be
either choke arrangements with screw conveyor flights removed, rotary valves,
or automatically operated double valve seals. Fresh solvent or reclaimed
solvent is added as needed, usually through preheaters or heat exchangers.
247
-------
The following refining processes, depicted in Figure 28, are typical
although they may differ in detail at various plants. Miscella from the
extractor generally flows to a working storage tank and thence to filters,
flash or pre-evaporators, and finally to stripping columns or stills usually
operated under partial vacuum. Steam is used for necessary heating and heat
exchangers are utilized where practical. Solvent vapors are condensed and
returned to a solvent working tank after removal of water by decantation.
Maximum operating temperatures usually do not exceed 250°F. Desolventized
oil may be pumped to storage or further refined depending on plant facilities.
It is customary to vent the extraction and solvent recovery equipment through
condensers, which are equipped with mineral oil absorption towers for the re-
covery of any traces of solvent vapors.
Spent flakes from the extractor are carried by closed screw or drag con-
veyor through a desolventizer. Four types of desolventizers are in use:
(1) desolventizer-toaster system, (2) steam-jacketed conveyor, (3) flash de-
solventizer, and (4) vapor-desolventizer-deodorizer system. Solvent vapors
released in this operation are condensed and returned to the solvent working
tank.
From a desolventizer-toaster system, the meal is dried first in a rotary
steam tube dryer and it is then cooled by air before being sent to a grinder
and storage. Meal from a steam jacket, flash dryer and vapor desolventizer-
deodorizer systems does not need to be dried.
Some U.S. soybean processors take the meal a step further. They send
the toasted soybean meal through a protein extraction process that prepares
soy protein for human food use. Much of this protein is currently used as
meat extenders and for soy flours.
Air Pollution Sources, Emission Rates, and Effluent Properties
The sources of air pollution in a soybean processing plant can be
grouped into three broad categories: (1) soybean receiving, handling,
and drying operations; (2) soybean processing operations; and (3) soybean
meal load-out operations. Table 141 presents some of the more significant
potential sources in each category.
Emission sources associated with the grain receiving and handling opera-
tions are similar to those involved in all grain handling storage operations.
The grain unloading, grain cleaning, and grain drying operations are the most
significant emission sources in this part of a soybean processing facility.
248
-------
CJ
CO
a.
60
co
co
0)
o
o
(0
0)
o
CO
c
o
•H
•U
O
a)
CO
60
d
0)
S-i
•fl
o
60
W
fe
O
i—l
M-l
a
-------
Table 141. POTENTIAL SOURCES OF AIR POLLUTANTS IN SOYBEAN
PROCESSING PLANTS
I. Grain Receiving, Cleaning,
Drying and Storage
1. Grain unloading
2. Elevator leg vents
3. Garner and scale vents
4. Trippers, conveyor
transfer points
5. Grain cleaner
6. Grain dryer
II. Soybean Processing
1. Cracking rolls
2. Dehulling system
3. Hull toaster
4. Hull grinding
5. Bean conditioner
6. Flaking mills
7. Desolventizer-toaster
8. Meal dryer
9. Meal cooler
10. Meal grinder
11. Solvent vapor recovery system
III. Product Shipping
1. Meal loadout
The major emission sources in the soybean processing section of the
plant are the product recovery systems used on the dehulling equipment and
the hull grinders and the meal dryers and coolers.
Loading of the finished meal into trucks or railcars can present a
source of dust emissions depending on the configuration of the loading shed.
Tables 142, 143, and 144 summarize available information on measured
emission rates from various sources in soybean processing plants. The data
for a truck dump pit shown in Table 142 were obtained by an EPA contractor
using the latest testing methods (Test Method EPA-5). The data in Table 143
were obtained with a Universal Oil Products stack sampler (UOP Sampler No.
13-16). This unit employs a cyclonic separator for coarse particles ahead
of the filter bag of~1-1/4 ft2 of area. The pressure drop is measured
across the cyclonic separator and continually monitored during the tests by
leads attached to a Dwyer Magnehelic gauge. A glass jar collects the mate-
rial spun out in the cyclonic separator. The sum of this weight of mate-
rial collected in the glass jar plus the weight of material collected in the
bag constitutes the particulate emissions in the measured air volume of the
air sampled.
250
-------
•**
t\
p^
^3
,_j
PH
0
CO
<
<
g
H
CO
SH
CO
P^J
o
H
H
P§
M
PM
CO
^
H
PM
PM
g
K^
U
J~TJ
P CO
cj cu
CO CJ
PH O
SJ
c a
o
•rl C
CO O
CO 4J
•rl ^-,
CTi CM
r-l CO
rM
(004-1
O M CJ
hJ 4J W
C -^
4J 0 rl
CO CJ 6C
W 60
C
^
CO
CU
rJ
r~ CM
O** *^* CO
O CM O
O 0 0
• • •
O O O
cu
4-1
CO x-.
P4 H
JS
CO ^^
CO CO
cu c
cj o
O 4-1
M ^
PM
fO ^d~ •
0 r-l
i— 1
lj i i
cu
M CU O
ft }-i CO
CO
a
cu
4-)
CO
^t
4-1 CO
•H
ft C
CU
CJ
3
O
CO
O
ft *rl
0 4-1
3 co
f^J Jj
•rl
L> f\
rb t-M
CJ CO
3 to
H
1
CO
4J
CO
TJ
C
•rl
Cfl
4J
^
O
o
4-1
13
CU
CO
3
cu
cu
CO
CU
rl
3
T)
CU
CJ
O
rJ
ft
60
C
•i-4
r~^
ft
0
CO
CO
IO
T3
o
rC
4J
(U
g
^3
PM
~rt|
3
PH
g
M
co
CO
W
CJ
o
as
PM
5
M
O
CO
<
EH
o
c
cu
(U
^i
u
cu
CJ
J_j
^
0
CO
CO
60 E
i-l CU
CU 4->
A CO
CO £*,
r-l CO
o
Pn
to
CT*
•
O
f^
,
to
0
o
o
VI
CM
r-l
O
0
10
CM
r— 1
cu
C
0
r— 1
O
^
CJ
6
S
4J
CO
CO >,
CU CO
^
CO 60
r-l C
n i - t
r— 1
cu o
4J O
•rl O
rt
*g
251
-------
H
^4
^
Cu
U
M
CO
CO
w
CJ
o
(A
PH
t_
^~J
PQ
C/3
^^
H
C/3
j- .
prf
CD
O
CO
@
H
CJ
H
W
CO
M
g
CO
w
H
s
a
0
I-l
CO
CO
M
E)
g
erf
CD
CO
w
s
^
st
*cr
r~l
CU
^H
CO
H
Cl
O
CO
CO
•r4
6
w
fi
o
•H
co
CO
•H
W
CO
4J CO
C cu
CO O
i— I O
PM to
PM
CO
CO
O
O
4J
O
CO
CU
3
cu
4J
*
cu
€
r-l
O
r-l
0
4-1
Cl
o
U
's
*o
*-s^
rO
1—4
s_^
in
CM
0
o
•
o
"' "
CO
•a
fi
vj-
•
s
^^
&*
CO
13
3
rd
o
o
m
en
9
M-l
a
CTi
vO
oo"
4-1
C
s
a
^
D-
W
CU
o
.-t
U
t**>
CJ
M
CU
4-J
CO
O
CU
CJ
3
c
CO
4J
1-1
1— 1
J3
s
00
en
o
0
»
o
CM
•
>
cu
c
o
o
m
0
o
*
0
m
•
o
CM
O
o
m
en
oo
o
vO
CM
CM
S X
CM
~— '
CU
O
1—1
CJ
^
o
M
a)
r-l
O
o
CJ
CO
cu
IS
t— 1
en
0
o
o
•
o
J^.
•
1-1
I-l
o
o
m
en
o
m
0
oT
cu
o
i— i
o
^1
CJ
^
cu
^
r-i
efl
-------
A Carter-Day ISO-KINETIC dust sampler was used to obtain the samples
for the data reported in Table 144.
Some estimates of emission rates from soybean processing plants are
presented in Tables 145 to 147.-t£/ The estimates were provided by various
soybean processing plants which responded to the emissions inventory
questionnaire.
CORN WET MILLING
The corn refining or wet-milling industry has grown in its 120-130 years
existence into the most diversified of the grain processing industries. As
the outflow of its integrated operations, the corn refining industry pro-
duces hundreds of products and by-products. The industry's products have so
many diverse and multiple applications that they cut across defense, civilian,
health and national interest uses.
Corn Wet-Milling Process
In the corn wet-milling process, the corn kernel is separated into four
principal parts: (1) the outer skin, called the bran or hull; (2) the germ
(containing most of the oil); (3) gluten, a high-protein component; and (4)
starch. From a 56-lb bushel of corn, approximately 32 Ib of starch are pro-
duced, about 14-1/2 Ib of feed and feed products, about 2 Ib of oil, and the
remainder is water.
The overall corn wet-milling process, as illustrated in Figure 29,
consists of several distinct segments: (1) the separation process, which
divides and isolates the components of the corn kernel to obtain starch as
the principal end product and steepwater, oil, and feeds as by-products;
(2) the hydrolysis process, which converts some of the starch to syrup or
dextrose; and (3) the starch modification process which changes starch char-
acteristics by physical or chemical treatment.
Grain Receiving - Shelled corn is delivered to the wet-milling plant primar-
ily by rail and truck and unloaded into a receiving pit. The corn is then
elevated to temporary storage bins, then to scale hoppers for weighing and
sampling. The corn then passes through mechanical cleaners designed to
separate unwanted substances such as pieces of cobs, sticks, and husks, as
well as metal and stones. The cleaners agitate the kernels over a series
of perforated metal sheets; the smaller foreign materials drop through the
perforations while a blast of air blows away chaff and dust, and electro-
magnets draw out nails and bits of metal. Coming out of storage bins, the
corn is given a second cleaning before going into "steep" tanks.
253
-------
CO
0
1 — 1
EH
H
O
CO CO
W
H CO
05 O
M
IS 03
O
CO
CO EH
H X> O
0) rH
cu P ^
4-1
CO rH
OS O
C 4-1
o e
•H O
m CJ ^
en MH oo
•H 4-1 O O
B co cn o
W 3 *-«. O
Q l-i •
OC 0
N— >
X! O
--J CM
0) X> I"1
O O i-ll
4J -r-l ^->
13 0)
CO O
O
!_!] .1—1
t— 1 f^
o
CO 4J ^^
3 C >W
a o o CM
O CO 00
i-i O
CO
i
3 ^> O
rH g 0
O M-l O
^> O •*
CO rH
CO
O
M
01
rH -H
O CO M-<
r4 CJ
•W -1-1 O
a > -H
O CU J-i
CJ Q X>
CO
fa
•H M
P, 0)
bO co
CO p, fi C
CJ E3 -i-l CO
M 3 > M
O Q)
CO .*! CJ T)
CJ CO C!
3 r4 CO
H
1 1 1 1 1 1 1
u-i
CM
1 1 1 1 i— 1 1 1 1
O
o o o ooooo
in o o moooio
*^" CO rH rH i — 1 i — 1 rH (^
CO 00
rH O CO OOfOOOrHVQ
co in CM mcMocom
o o o ooooo
o o o ooooo
,
O0-i-lcflO0'HC!> ocjcow
>i3>M>-13!>co V-i
a)To-i-i4Jcu*OT-i > i-i o
r* CO ^ CU r4 rH CU r4 r4 CU ^
C4iJOT3C!4iiOCUCoa
cJ3McocJ3J^ViCOCO-i-tT-lT-(C!
JH M CO cJMt-iMO
H H O copi-iPHEHO
254
i i i
i i i
o o o
O CO l^-
»J- CN CM
ON
00 O C^
U-1 rH O
o o o
0 O O
rH 00 OO
00 ^O i— 1
CM CO
rJ rJ H
cu cu cu
rH i~H i~H
•lH -1-1 T-l
m MH M-I
o o o
•H -H -H
CO CO CO
fa fa fa
CO CO CO CO
00 00 00 00
CO co CO
O CO O CO O CO O
1 1 ^| [-i j | ] i j | 1 1
CO O CO O CO O cO
^ r**» r* £*•> ^ K^* J^
co cu co co cu co cu
rH ^ rH ^ rH ^ rH
CO r* CU C CU G CU
O O O
U U U
-------
H
00
W
K"j
ry*
Q
1-jT
M
O
55
wcni
>< cA
O H
C/l 5S
5°* ZH
fi Qu
Pi
2
C/3 M
W C/l
H C/3
S U
O
p-^ CKj
O CM
H
co 125
co •<
H CO
c/>
£3 CO
a D
o
Q M
W 05
H <
S ^
M
H
CO
w
VJD
j.
r-l
CU
1— 1
CO
H
j_,
O
4-1
O
CO
LZH
c
o
•1-1
CO
CO
•r-l
S
w
4-1
CO
pi
T3
CU
CO
CO
CU
O
O
a
p
^f*>
*~
o
1— 1
60 >-
C CO
•H
CO
CO
4)
O
0
S-i
P-i
O r-H
M 0
p4 ^ QJ
4J O
C C T-4
O O >
•i-l O CU
co P
CO 4-1
•i-l CO
S 3
w Q
t— 1
O
rW
4J
C
o
o
CU
o o
•1— ' *rH
>
•"O CU
CO Q
,3
4J
CO
a
CU
S
3
i— i
O
£>
CO
CO
O
i— <
0
r^
4-J
C
o
^
13
— .
^
n
v~'
^j-
CM
i-l
O
•
o
0
o
in
«\
00
en
J-i
1— {
o
CN
"^-^
/-^v
M-l
O
W
J_i
v5
m
r^*
O
o
•
o
*~*^
^
Lc~]
^^
P
I— 1
o
o
o
A
0)
Q
s^
CO CJ
Q CO
I >
!-( 1
cu >,
4J CO
H Q
fO
O
a u
u
t-i
3
O
CO CU
2 £
>-, 13
O
CO
x^
r-l
O
•
o
o
o
o
•s
o
in
CN
CN
O
•
O
VD
CM
m
en
o
0
o
o
vo
oo
1— 1
CU
CO
3
O
JZ
a
0)
0)
o
03
C M
CO CU
J3 tt
^1 'Tj
O
CO
oo
m
o
•
o
0
o
in
t\
f^.
co
o
ON
m
en
o
•
o
o
o
m
^
o
o
o
o
o"
o
en
CU
CO
3
0
C
CU
CU
M
O
C/3
C H
CO CU
CU >>
rO M
^> 13
O
CO
oo
en
O
»
0
o
o
m
M
fx.
CO
0
*sD
in
o
*
o
o
o
CN
a\
r- 1
CD
O
O
O
in
CM
T— i
CU
CO
3
O
j2
C
cu
cu
±4
o
OT
C >-i
CO CU
CU >,
^s T3
O
cn
255
-------
" "^
o o
o o
LTi
;o o o o o
O m o O O
o o o o o o
o o o o o o
o o o o o o
III
O O U
X >* >,
o a o
Soj a) D oj
C 13 C C
o o o o o -
U O O U O
256
-------
SHELLED CORN
¥
STORAGE AND
CLEANING
STEEPWATER
EVAPORATORS
STEEPWATER
CONCENTRATES
STEEPWATER
STEEP TANKS
DEGERMINATORS
GERM SEPARATORS
GRINDING MILLS
HULL
WASHING SCREENS
FEED DRYERS
GLUTEN
CENTRIFUGAL
SEPARATORS
FEEDS
STARCH
WASHING FILTERS
! STARCH |
j MODIFYING I
GERM
WASHING & DRYING
OF GERMS
SYRUP & SUGAR
CONVERTORS
1
SYRUP
REFINING
'
*
DRUM OR SPRAY
DRIERS
SUG
CRYSTAL
Figure 29. General flow diagram for corn wet milling plant.
257
-------
Steeping - Steeping, the first step in the process, conditions the grain for
subsequent milling and recovery of corn constituents. This process softens
the kernel for milling, helps break down the protein holding the starch par-
ticles, and removes certain soluble constituents.
The steeping process consists of a series of tanks, usually referred to
as steeps, and might be termed a batch-continuous operation. Each steep
holds about 2,000 to 6,000 bu of corn, which is submerged in continuously re-
circulating hot water (about 50°C). Sulfur dioxide in the form of sulfurous
acid is added to the incoming water to aid in the steeping process.
As a fully-steeped tank of corn is discharged for further processing,
fresh corn is added to that steep tank. Incoming water to the total steep-
ing system is derived from recycled waters from other operations at the mill,
and is first introduced into the tank with the oldest corn (in terms of steep
time) and passes through the series of steeps to the newest batch of corn.
Total steeping time ranges from 28 to 48 hr.
Steepwater Evaporation - Water drained from the newest corn steep is discharged
to evaporators as so-called light steepwater containing about 6% of the orig-
inal dry weight of the grain. On a dry weight basis, the solids in the steep-
water contain 35 to 45% protein and are worth recovering for addition to feeds.
Such recovery is effected by concentrating the steepwater to 30 to 55% solids
in triple-effect evaporators. The resulting steeping liquor, or heavy steep-
water, is usually added to the fibrous milling residue which is sold as animal
feed. Some steepwater may also be sold for use as a nutrient in fermentation
processes.
Milling - The steeped corn then passes through degerminating mills which tear
the kernel apart to free the germ and about half of the starch and gluten.
The resultant pulpy material is pumped through liquid cyclones or flotation
separators to extract the germ from the mixture of pulp, starch, and gluten.
The germ is subsequently washed, dewatered, dried, the oil extracted, and the
spent germ then sold as corn oil meal.
The product slurry passes through a series of washing, grinding, and
screening operations to separate the starch and gluten from the fibrous mate-
rial. The hulls are discharged to the feed house where they are dried and
used in animal feeds.
At this point, the main product stream contains starch, gluten, and
soluble organic materials. The lower density gluten is then separated from
the starch by centrifugation, generally in two stages. A high quality gluten
of 60 to 70% protein and 1.0 to 1.5% solids, is then centrifuged, dewatered,
dried, and added to the animal feed. The centrifuge underflow containing
the starch passes to starch washing filters to remove any residual gluten
and solubles.
258
-------
Starch Production - The pure starch slurry can now be directed into one of
three basic finishing operations, namely ordinary dry starch, modified
starches, and corn syrup and sugar. In the production of ordinary pearl
starch, the starch slurry is dewatered using vacuum filters or basket cen-
trifuges. The discharged starch cake has a moisture content of 35 to 42%
and is further thermally dewatered by one of several different types of
dryers. The dry starch is then packaged or shipped in bulk, or a portion
may be used to make dextrine.
Modified starches are manufactured for various food and trade industries
for special uses for which unmodified starches are not suitable. For example,
large quantities of modified starches go into the manufacture of paper pro-
ducts, serving as binding for the fiber. Modifying is accomplished by treat-
ing the starch slurry with selected chemicals such as hydrochloric acid to
produce acid-modified, sodium hypochlorite to produce oxidized, and ethylene
oxide to produce hydroxyethyl starches. The treated starch is then washed,
dried, and packaged for distribution. Since most chemical treatments result
in a more water soluble product, wastewaters from the washing of modified
starches may contain a large concentration of BOD. In addition, because of
the presence of residual chemicals, these wastewaters often cannot be reused
and must be discharged to the sewer.
Syrup and Sugar - In most corn wet mills, about 40 to 707» of the starch slurry
is diverted to the corn syrup and sugar finishing department. Syrups and
sugars are formed by hydrolyzing the starch, partial hydrolysis resulting in
corn syrup and complete hydrolysis producing corn sugar. The hydrolysis step
can be accomplished using mineral acids or enzymes, or a combination of both.
The hydrolyzed product is then refined, a process which consists of decolori-
zation with activated carbon and removal of inorganic salt impurities with
ion exchange resins. The refined syrup is concentrated to the desired level
in evaporators and cooled for storage and shipping.
The production of dextrose is quite similar to that of corn syrup, the
major difference being that the hydrolysis process is allowed to go to com-
pletion. The hydrolyzed liquor is refined with activated carbon and ion ex-
change resins to remove color and inorganic salts, and the product stream is
concentrated to the 70 to 7570 solids range by evaporation. After cooling, the
liquor is transferred to crystallizing vessels where it is seeded with sugar
crystals from a previous batch. The solution is held for several days while
the contents are further cooled and the dextrose crystallizes. After about
60% of the dextrose solids have crystallized, they are removed from the liquid
by centrifuges, dried, and packed for shipment.
A smaller portion of the syrup refinery is devoted to the production of
corn syrup solids. In this operation, refined corn syrup is drum- or spray-
dried to generate corn syrup solids, which are somewhat more convenient to
use than the liquid syrup.
259
-------
Air Pollution Sources, Emission Rates and Effluent Properties
The diversity of operations in a corn wet milling plant results in
numerous and varied potential sources of air pollution. It has been re-
ported that the number of process emission points number well over 100 at
a typical plant. Table 148 presents some of the potential sources of air
pollution in corn wet milling plants.
Emission sources associated with the grain receiving, cleaning, and
storage are similar in character to those involved in all grain elevator
operations.
Table 148. POTENTIAL SOURCES OF AIR POLLUTANTS IN CORN WET MILLING PLANTS
I. Grain Receiving, Cleaning
and Storage
1. Grain unloading
2. Elevator leg vents
3. Garner and scale vents
4. Trippers, conveyor
transfer points
5. Grain cleaner
III. Conversion Process
1. Dextrose drying
2. Corn syrup solids
drying
3. Spent carbon regenerator
II. Separation Process
1. S02 absorption tower
2. Steep tanks
3. Germ drying
4. Gluten drying
5. Feed drying
6. Feed pellet mill
(if used)
7. Pellet cooler
(if used)
8. Starch drying
9. Starch milling
260
-------
Table 82, p. 122 presents recently obtained emission rate data for
corn receiving and handling operations.
The various drying operations performed in the separation process are
major sources of particulate and odor emissions. Several different types
of dryers such as ring, flash, rotary, belt, and steam tube are used to
dry feed, gluten, germ, and starch. Since a product recovery system (e.g.,
cyclone collector) is used in conjunction with the dryers, the actual source
of emissions is the product recovery cyclone. Discussions with plant mana-
gers have indicated that the feed drying operation is the most difficult
o o o / /
source of air pollution to control. »' The feed drying operation is also
considered the worst fire hazard followed by the gluten and starch drying
processes.^-j-^-t/ The starch drying process also presents an explosion
hazard.^:/
Dextrose and corn syrup solids drying are also emission sources. As
with the other drying operations, the actual emission point is the product
recovery unit. Spray dryers used for the drying of corn syrup solids are
reported to emit particulates that are difficult to collect.—' Regenera-
tion of the granular carbon used in dextrose and syrup refining may also
result in the emission of particulates.-i2/
The emission rates from the drying operations will vary with the type
of dryer and product recovery system utilized. Table 149 presents some
data on measured emission rates from drying operations in various corn wet
milling plants. The data for Plants A and B were obtained with Western
Precipitation Sampling equipment, while RAG equipment was used at the other
plants.
Table 150 summarizes the results of emission testing activity conducted
by one company using emission testing equipment and procedures which they be-
lieve are applicable for use on exhaust streams of high moisture content.
The exact test procedures are not known and the validity of the data in
Table 150 cannot be assessed.
Table 151 presents data on the properties of effluent streams from
cyclone product collection systems on various dryers in corn refining plants.
The data in Table 151 on moisture content in the gas stream were obtained by
material balances around the dryer units. The outlet temperatures and gas
volumes were obtained from discussions with individual plant managers and
emission inventory questionnaires.
261
-------
,
OJ O •
•—< h-J i
O C C O J-j
CB 6£
CM «
262
-------
! -
cu re
-------
TO O
OS U
4J O
-------
CO
3
PH
O
g
M
od
IS
8
o
(—1
^_l
pM
CO
a!
O
En
S
Q
S
0
CO
CO
l-l
§
I
CO
•s
^"
m
01
o
CO
Vl
O
4-1
wol
fn ^-,
C
e o
0 4J
•H -^
CO ,Q
CO t-l
•H ^
1
^
xO
•
o
i
CM ^O
en en
0 0
a
o~-~.
•H Ol
4-1 /~.
CO -.
o o o
r-t t-l
O O t^ > 0 i-l
oh o o 01
O T3 O O t-l
01 11 r-J
Vl T3 H TJ C8
0) 01 Vl
4-1 Ol 4J 0) CO
o *u u iw o.
3 3
•a c T3 e cl
O O o 0 -H
Vi Vi
PH CM
^
^ i
C
eg
px,
en
04
•
o
1
CM
o
C7\
CM
o
1
f-
CM
0
00
o
1
CTi
OS
8
o
A
v£>
ON
13
0
CM
CO ^-^
0)
a 6
0 01
r-l U >-s
O CO CO
>. >-, CU
CJ CO -i-l
U
>, 4J 01
Vl Vl CO
a C
O CO -H
0 C
iu a) co
Vl Vl Ol
u a
4J O
O T) t-1
3 0) 0
T5 01 >,
O "4-1 O
VI
PM
CM
•
r-l
1
ON
en i i
o
00
en
o
i m CT>
r-l ON
O
O
•t 1 1
t-l
en
C C C
O 0 o
a) 01 01
c c e
o o o
r-l r-l r-H Vl
O U U Ol
O U Ol U Vl
t^ T?
CD VI CU Ol 01
> CU > T3 > 4J
O >•, O 0) O 3
O Vl O Ol U r-4
CU T) 01 M-l CU M
Vl Vi Vi
13 >, >-
O 4J O CO U CO
33 3 4J 3 4-1
*w i— 1 *d O TJ O
O SO O Vi o H
n u vl
PM PM CM
m
4-1
a
n)
PM
•
Vi
a)
1— 1
o
o
0
•
a) vi
• (3 0
Vl O
CU l-l • V4
r-i o e u
O >, CO >>
O O 01 H
o vi -a
S 4-1
Vi O CO O
on 4J
M-l 4J
Vl CO 4-1
01 01 3 3
>•, 4-1 co a,
Ci co J3 13
•O rl X -rl
O C C
4J O 0) O
•i-l (3
4-1 CO O 'd
3 CO r-l 01
a. v-i o co
(3 S >. CO
i-i ta o pa
col ,al o| t3|
265
-------
Plant A.
Table 151. CHEMICAL AND PHYSICAL PROPERTIES OF EFFLUENTS FROM PRODUCT
COLLECTION SYSTEMS (CYCLONES) ON DRYER EXHAUSTS (CORN WET MILLING PLANT)
Source
Specific
Gravity
of Dust
Outlet
Temperature Flow Rate
Moisture
Content
of Gas Stream
(Ib H20/scf)
I. Feed Drying
a. primary rotary
flash dryer -
single cyclone
collector
0.5
225
0.0079
II. Gluten Drying
a. rotary flash
dryer - single
cyclone collector
0.9
200
40,000
0.0046
Plant B.
II.
Feed Drying
a. secondary rotary
dryer - single
cyclone collector
Gluten Drying
a. rotary gluten
dryer - single
cyclone collector
0.5
0.9
200
156
29,500
16,300
0.012
0.0077
Plant C.
I. Feed Drying
a. primary flash
dryer - single
cyclone collector
b. secondary rotary
dryer - single
cyclone collector
II. Gluten Drying
a. 3 pass rotary
dryer - single
cyclone collector
b. rotary flash
dryer - single
cyclone collector
III. Starch Drying
a. flash dryer -
single cyclone
collector
b. Barr-Murphy ring
dryer - fabric
filter collector
0.5
0.5
0.9
0.9
1.5
1.5
160-315
140-170
200
40,000
14,000
14,000
40,000
40,000
60,000
0.0063
0.009
0.006-0.007
0.0036
0.002
IV. Corn Syrup Solids Drying
a. flash dryer -
single cyclone
collector
25,000
0.003
266
-------
The Corn Refiners Association has contracted studies to identify the
nature of gaseous emissions from feed dryers.— Condensable organic con-
stituents in stack effluents from 13 different dryers in five plants were
sampled. Analysis of the samples indicated that the dryer exhausts all con-
tained the same group of organic compounds from a qualitative standpoint.
Ten low-molecular-weight acids, 10 aldehydes, and an amine were identified
by a combination of mass spectrometry and gas chromatography. Table 152
summarizes the data for the acids and aldehydes.
267
-------
OOOOOi—l
O-d-r-iOOOOOtNOJCO
•—loooomoooojco
r-HOOOOrHOOOfvJ
OOOOOOOr-lOO
OvOOOOOOr-HO<]-jr-1
noooooooooj-vi-
A A A A A A '
OOOOOOo~icMOiNCO
OOi-^Oi—(OrOOOr--
\oOOt-<,
o jz > -d a) •—i
O CJ O 4J >^ "O i—I r—I *O OJ ;-; >^ J_i
•H )-J -H t-l -r-l O -H O*3 QJCdHI-lCdi—IrHTJllOtJ
CJO-LJ^t—( nj i—i i—* H
•H-HDiJcd!—tflJD-O^O cO.HScdr-i3i-^>cd>ib
a M K i w i w i a) ^n WQ^mojiao^iuji!
268
-------
REFERENCES
CHAPTER 3
1. "Agricultural Markets in Change," U.S. Dept. of Agriculture, Agriculture
Econ. Report, No. 95, July 1966.
2. "Locating, Designing, and Building Country Grain Elevators," United
States Department of Agriculture, Information Bulletin No. 310,
December 1966.
3. Private communication, Mr. Tim Devitt, PEDCo-Environmental Specialists,
Inc., Cincinnati, Ohio, June 1972 (Source tests conducted for private
client).
4. "Background Information for Federal Performance Standards - Grain Handling
and Milling," PEDCo-Environmental Specialists, Inc., CPA 70-142, July 1971.
5. Private Communication, Mr. Richard Coonrod, Pillsbury Co., January 1973.
6. Private Communication, Mr. F. J. Belgea, Pollution Curbs, Inc.,, St. Paul,
Minnesota, June 1972.
7. Emission Inventory Questionnaires, Grain Elevators, MRI Project No. 3546-C,
Contract No. 68-02-0213.
8. Schoeff, R. W., "The Formula Feed Industry," Feed Manufacturing Tech-
nology, published by American Feed Manufacturers Association, Chicago,
Illinois, 1970.
9. Environmental Controls for Feed Manufacturing and Grain Handling;
American Feed Manufacturers Association, Chicago, 1971.
10. Emission Inventory Questionnaires, Feed Mills, MRI Project No. 3546-C,
Contract No. 68-02-0213.
11. Private Communication, Mr. Charles Anderson, Cargill, Inc., Minneapolis,
Minnesota, October 1971.
12. Private Communication, Mr. Nick Scheuer, Hubbard Milling Company,
Mankato, Minnesota, September 1971.
269
-------
13. "Particulate Emissions and Process Conditions at Representative
Alfalfa Dehydrating Mills," Final Report, Midwest Research Institute,
prepared for American Dehydrators Association, 19 November 1971.
14. "Particulate Emissions from Alfalfa Dryers - The Effectiveness and Cost
of Control," Interim Report, American Dehydrators Association, prepared
for Environmental Protection Agency (Grant No. R 801446), April 1973.
15. "Air Pollution from Alfalfa Dehydrating Mills," USDHEW Technical Report
A60-4, 1960.
16. Private Communication, Mr. Kenneth Smith, American Dehydrators Associ-
ation, September 1969.
17. Compilation of Air Pollutant Emission Factors, EPA Publication AP-42,
February 1972.
18. Larsen, R. A., "Milling," Chapter 9, Cereals as Food and Feed, Avi
Publishing Company, Westport, Connecticut, 1959.
19. From Wheat to Flour, Wheat Flour Institute, Chicago, Illinois, 1965.
20. Fanshawe, S. R. D., "Screenroom Machinery and Processes," Chapter 4,
Volume I, Practice of Flour Milling, Northern Publishing Company,
Ltd. Liverpool, England, 1966.
21. Emission Inventory Questionnaires, Flour Mills, MRI Project No. 3546-C,
Contract No. 68-02-0213.
22. MacKenzie, J., "Determination of Dust Concentration in Flour Mill
Suction Systems," Bulletin--Association of Operative Millers,
pp. 1948-1951, March 1952.
23. "Report of 1950 Subcommittee of the Research Committee of Association
of Operative Millers on Further Studies of Dust Collection from
Roll Exhaust Systems," Bulletin-Association of Operative Millers,
pp. 1854-1859, November 1950.
24. United States Department of Agriculture, Wheat Situation, Economic
Research Service, November 1968.
25. Berger, D. W., and D. E. Anderson, "Analysis of Production, Processing, and
Consumption--Markets for Durum Wheat," Agricultural Economics
Report No. 77, Department of Agricultural Economics, Agricultural
Experiment Station, North Dakota State University of Agriculture
and Applied Science, Fargo, North Dakota, October 1971.
270
-------
26. Matz, S. A., "The Chemistry and Technology of Cereals as Food and Feed,"
Avi Publishing Company, Westport, Connecticut, 1959.
27. Stiver, T. E., "American Corn Milling Systems for De-Germed Products,"
Bulletin of Association of Operative Millers, pp. 2168-2179, June
1955.
28. Easter, W. E., "The Dry Corn Milling Industry," Bulletin of Association
of Operative Millers, pp. 3112-3115, July 1969.
29. Salisbury, D. Kent, and W. R. Wichser, "Oat Milling—Systems and Products,"
Association of Operative Millers Bulletin, May 1971.
30. Private Communication, Mr. Maurice Schrag, Hart-Carter Company,
Minneapolis, Sept 1971.
31. Private Communication, Mr. J. McPhail, P&S Rice Mills, Houston, Texas,
October, 1971.
32. Fiedler, R. E., "Economics of the Soybean Industry," Journal of the
American Oil Chemists' Society, Vol. 48, 43-46, January 1971.
33. Private Communication, Mr. J. W. Williams, CPC International, Inc.,
Kansas City, Missouri, August 1971.
34. Private Communication, Mr. W. Graham, American Maize-Products Company,
Roly, Indiana, September 1971.
35. Private Communication, Dr. J. D. Commerford, Corn Refiners Association,
Washington, D. C., December 1971.
36. "Air Pollutant Emission Factors," Report of the Division of Air Quality
and Emission Data, National Air Pollution Control Administration;
April 1970, prepared by TRW Systems Group of TRW, Inc., Contract No.
CPA 22-69-119, p. 5-5.
37. Thimsen, D. J., and P. W. Aften, "A Proposed Design for Grain Elevator
Dust Collector," J. Air Pollution Control Association, 18, 738-742,
November 1968. ~~
38. Source test reports provided by Mr. Doug Fiscus, Pillsbury, Inc.,
September 1972.
39. Private communication from Mr. Ken Woodard, EPA/OAP (trip report,
grain dryer test, Colorado, January 22, 1973).
271
-------
40. EPA Emission Testing Report 73-GRN-4, Part I: Summary of Results.
41. Myers, N. W., "Grain Dryer Particulate Emission Tests," Myers-Roly
Engineers, State of Illinois Institute for Environmental Quality
Project No. 10.024, March 27, 1973.
42. Personnel communication, Mr. C. L. Anderson, Nutrena Feed Division,
Cargill, Inc., April 1973.
43. Emission Inventory Questionnaire, Soybean Milling, MRI Project No.
3546-C, Contract No. 68-02-0213.
272
-------
CHAPTER 4
TECHNICAL AND ECONOMIC ASPECTS OF DUST CONTROL SYSTEMS
INTRODUCTION
Systems for the control of dust emissions from grain and feed operations
consist of either extensive hooding and aspiration systems leading to a dust
collector or methods for eliminating emissions at the source. These latter
methods can be as simple as interventing the head and boot of a bucket eleva-
tor or use of enclosed conveyors in pressurized elevators. The incentives
for controlling emissions, in addition to complying with air pollution regu-
lations, include recovery of valuable materials, sanitation, and reducing
the fire and explosion hazards.
Where practical, techniques which eliminate the sources of dust emission
or which retain it in the process are the most effective. Enclosures or
covers on bins, tanks, and hoppers, and the replacement of worn-out parts
can help eliminate sources of dust emissions. Emissions can also be elimi-
nated by minimizing the number and size of openings, and maintaining the
system's internal pressure below the external pressure; thus air flows into,
rather than out of, the openings. Such systems are in use in the basements
of elevators where the conveyors are completely enclosed and the basement
is slightly pressurized.
When methods for eliminating the sources of dust emission are not prac-
tical, control systems must be used which capture the dust as it is entrained
or suspended in the air, and convey it to a dust collection device.
Thus, eliminating dust at the source and capturing the entrained dust,
followed by separation in a collection device, are both important methods
for controlling emissions. Although a number of facilities have taken steps
to eliminate dust emissions at the source, the majority have installed an
aspiration system using one of the common collection devices such as cyclones
or fabric filters. The estimated effectiveness of these practices in the
major segments of the grain and feed industry is listed in Table 153.—
273
-------
Table 153. ADEQUACY OF TYPICAL DUST CONTROL SYSTEMS -
CURRENT STATUS, 19723/!/
Industry Segment
Flour mills - milling process
Flour mills - cleaning house
Flour mills - grain storage
Soybean (dry) processing
Corn mills - entire plant
Rice mills - entire plant
Feed mills - entire plant
Terminal elevators
Country elevators
Alfalfa mills
Retention-
Adequacy
of Typical
Practice
8
7
5
6
6
6
5
4
2
3
f 1
Capture^'
Adequacy
of Typical Separation-/
Systems
9
8
5
6
6
6
5
4
2
3
Filters (7,)
50
10
10
25
40
5
5
3
1
1
Cyclones (%)
50
90
90
75
60
95
95
97
99
99
.a/ Opinion regarding the adequacy of dust retention efforts and collection
systems (Column 2) is presented by a scale from 0 to 10, in which 0
indicates complete inadequacy and 10 indicates complete adequacy.
b/ Effectiveness of practices which reduce or eliminate dust emissions at
the source.
cj Effectiveness of methods which capture the dust entrained in air at the
source.
d/ Approximate percent usage, industry average, of fabric filter and cyclone
devices by industry category.
274
-------
Technical and economic factors associated with dust control systems
suitable for use in the grain and feed industry are discussed in general terms
in the following section. Dust control practices for specific segments of the
grain and feed industry are presented in the section on p. 292 (Currently Used
Control Systems).
DUST CONTROL SYSTEMS
Control of emissions requires proper design of both the dust pick-up
and the contaminant removal system to adequately collect the contaminants at
the emission source, remove the contaminant from the carrier gas stream and
then exhaust the cleaned gas to either the atmosphere or back into the build-
ing. Thus, the design of the hoods, ducts, fans, and vents, plus the design
of the contaminant removal device must be carefully specified to insure an
effective emission control system. It is especially important that this
system be designed as an integrated unit with adequate capacity for current
and planned production.
Dust Capture Systems
Adequate design of the emission dust capture system is vital for effec-
tive air pollution control and in most cases the system must be individually
tailored for each process. Grain unloading, loading, and drying operations
represent some of the more difficult sources for proper dust pick-up whereas
for most other sources, the design of the emission comtainment system is
essentially straightforward. Air flow in the ducts must be high enough to
prevent the dust from settling out and plugging the duct. The air velocity
at the inlet or dust pick-up points must be high enough to capture the dust,
but not so high as to pick up grain or other products from the belts, transfer
points, etc. Duct velocities are usually above 3,000 ft/min and inlet air
velocities at openings range from 75 ft/min to as high as 2,000 ft/min.
Table 154 presents some data on design parameters for dust control systems
in grain and feed plants..?.' Additional information regarding design of hood-
ing and exhaust systems in grain handling operations is given in Reference 2.
Types of Air Pollution Control Devices
Cyclone collectors, fabric filters and wet scrubbers are used to control
emissions from the various grain handling and processing sources. Wet scrub-
bers have not found wide application because of the associated water pollution
potential and because they do not permit direct recycling of the collected mate-
rial. Due to tightening emission control regulations, fabric filters are now
being used on many sources which were formerly controlled by only low efficiency
275
-------
"
CO
(U
o
H
!>
W
l_]
t^
£3
H
P5
o
,3
M
CO
f§
H
CO
>H -^,
CO
O rJ
P^ HH
^
O OH
CJ D
0
H rJ
CO fc
03 <*
o
CO
CO ,_!
P^ 1-1
H S
W
^ Q
2 CTJ
< tn
ss
O
H
CO
Q
^j-
tn
r-l
tu
r-l
XI
CO
H
CD
e
•3
r-l
O
14
•r-l
CO
CU
r-l
CO
CU
o
CO
M-l
C
tu
0
CM
4-1
M-l
s e
O M-l
X! O
W
o
to O
<; r-l
^**>
nJ|
c
w
•r-l
CO
CO
O
*"O CO
O CM Q
O O CO
Si CO 1
CO
i— 1
0 X!
CO 4J
O
CO O
> co
60
C
d -H
o -o
•H CO
4J O
CO r-l
!-i
CU 60
O co
O en
•v
a T)
CU CU
CL CU
CO CX
to
4-1
r-l 4-1
CU r-l
XI CU
XI
e _
a E
M-l CX
M-l
0
0 0
CM O
CM
O
4-1 i-l
a)
a, >
3 0
l-G r£
-U 4J
T3 'O
•i-l -r-l
S £
4J U
r-^ i— 1
0) OJ
XI rO
M-I m
0 0
4J 4-J
M-l U-l
& S
M-l <-M
O U
0 0
m tn
rH CN
"-D
0 CO
1 P-
t i
4J 1
r-l C
CU -H
rQ J=
D 0
H H
tu
60
CO
JC
U
to
•H
13
r-l
CU
CO
4J
U-l
0
T— 1
1-1
CU
o
tn
•H
a
0
TJ
T— 1
CO
^_l
CU
4J
m
M-l
'^
CO
^^
CU
tn
CO
cu
o
C
M
WO
O
CO
„
in
o
CO
1
CO
1
1
J_(
o
4-1
CO
tu
r— 1
CU
o
H
C
•r-l
n
£•
M-l
O
O
in
m
)_!
CU
p.
to
4-1
cu
to
£D
,
4-1
CO
3
to
r*3
0)
•u
o
0)
•r-l
o
tn
C
•r-l
en
ti
0
4J
CJ
tu
CO
i
CO
CO
0
o
CN
4-1
e
M-l
O
O
O
r-4
in
0
CO
r
CO
>
p
o
4-1
CO
tu
r-l
CU
4J
tu
O
3
pa
j_j
tu
3
4J
O
to
M-l
3
ti
G
•U
I— 1
^3
S
o
u
to
O
C
•r-l
r!
0
CO
e
&0
C!
•i-l
C!
tO
a)
CJ
CO
4J
3
0
a
CO
M-l
O
r-l
CU
4J
CU
CO
•H
O
C!
•H
•
C
•r-l
00
•
e
•H
•
S
• r-l
VO
to
4-1
3
O
0
CO
M-l
O
.
o
a
i
e
•H
s
a
M-l
o
o
CM
II)
60
CO
CJ
to
•a
cu
tn
O
r-l
O
C
W
CO
£^
o
:
•r
^
4-1
0]
•H
^
CU
r-l
3
en
O
r-l
U
c
cu
(-?
60
3
0
4-1
4-1
t4-l
CO
i-l
t3
0 0
m o
CM CT\
r— 1 r— 1
0 0
in o
ON m
r— 1
in o
r^. in
wO CN
r-l
0 0
in in
m ON
mjo
CM
WO r-4
1 1
O VD
•
en
60
C
•H
C
CU
§•
0
in
r-
CM
O
m
CM
CM
o
0
ON
r— 1
0
o
in
r.
r-l
frj
M
*3"
CM
1
CM
r— 1
o
CO
CD
r-l
CO
O
tn
M-l
c
CU
a.
o
CM
M-l
E
M-l
O
O
O
CM
x 8 in. opening
c
•r-l
•it
C
B
M-l
O
O
in
ON
C
•H
e
3
X
m
CM
r-l
II
S
M-l
O
Exhaust, cfm
0
o
CO
^.
-U
•r*f
O
03
P
rt
o
^.4
OJ
•r-l
£
C
0
4J
CM
r— 1
O
4J
D
m
n
0
4J
CM
^^
i — 1
1
r-l
1
C
o
4-"
CN
r—l
O
m
ON
CO
p^
0
•U
CN
i— 1
1
i— t
J-J
QJ
O
o
u
iJ
cu
T)
e
•H
•o
cu
tu
o
o
CQ
p.
a
13
S-i
O
o
p.
cu
C1J
g
c
•1-1
XI
I-l
CU
c
r-l
CO
3
CU •
C
CX
P.
6
M-l
O
o
CM
I
00
p.
X!
-------
/— ^
"U
M
•I-l
,
O 01
>
•o c
0 0
O 0
M 01
-O rJ
cu 3
to co
0 O
i— 1 r-4
CJ 0
C! C
W W
CO
IJ
Ol
T3
Ol
01
M-l
- 01
C 60 to
O to M
•i-l 4-1 CU
" C -r)
CO Ol M-l
rJ CJ *H
I) M n
a 3 3
O PL, O-i
e
M-l
O
• CO CO O
-u in o O
to CM .J- WO
5
•s
W
CO
t-l
0)
4J
d
Ol
o
4-1
M-l
O
CO
a
3 -.-1 13
xi E o
4J ~~~.
M-l . 3 to
> XI 4J
rH 4-1 O
CO -H X 3
cu o m o 1-1 T3
C co 1-1 i-i m
•H a o CN i
r-l 18 4J O f-J •
^ o 4J cu 1-1 6
S a. > M-I
M-l U JD i£l O II O
CJ i-H
co E o
o o M-I o
O CO CJ CM
• •
M i-l
cu cu
a, a.
co co
4J t-l
Ol Ol
to to
P D
• •
4-1 4-1
CO CO
3 3
CO CO
01 CU XX
)H )-l CU 01
3 3
CO CO 4J 4J
O O CJ CJ
i— I i— t 0)0)
O O M V4
a a .H •!-<
W M Q Q
M
O
)-l X
CO 01 CU
•a a. >
a eu c
CO 00
4-1 XI O
CO CO
cu cu u
rH r-l ,-( 0)
rH CO CO t-l
O O O O
OS CO CO CO
4J
e
CU
6
4J
U
CO
a
S
0
o
~B
M-l
CJ
O
O
CM
0)
14
3
U)
0
1— 1
O
W
CO
IJ
cu
4J
M-l
•H
CO
CO
01
Jj
CO
cu
4-1
CO
iJ
00
CM
4-1
M-l
^^
E
M-l
0
O
o
rH
•
r4
CU
CU
a
o
XI
E
0
rJ
M-l
4J
CO
3
CO
•S M
ai cu
Cu
4-1 CO
O 4J
CU
r4 (1)
•H CO
0 0
4J
•r4
(X
(X
0
S
d
o
•H
4-1
• CJ
01 CU
> to
0 1
X< CO
CO CO
o
= r4 XI
CU O 4-1
00 T3
H 4-1 -rl
CO 3 S
X! 0
O CX 4J
CO CO rH
•H 01
QCM XI
4J
4J M-4 4J
rH ^ M-l
0) B --
CO MJ E
- O M-l
CJ
0) O
cu o o
C/> CN CTi
•
vD
O •
CO C
O
•* 'H T3
in 4J co
O 0 Ol
co cu xl
d
- d rJ
-,
••-I CU 00 CU
T3 CO rH
4-1 rH rH
4-1 3 rH 3
rH O •••) (X
Ol (X CX
PQ C/3 I/I
r4
CO
O
r4
(D
CX
CX
•i-l
U
H
cn
C
0
•r-f
•U
a
•H
^
fj
CO
r-j
rj
Ol
CO
h
o
M-l
CM
01
CJ
e
Ol
^
01
M-l
CU
K!
CD
01
co
"w|
277
-------
mechanical collectors. High efficiency mechanical collectors are being used
on several processes, where the high moisture content of the effluent streams
or other process requirements precludes the use of fabric filters. The fairly
dry nature of the dust, the low temperature involved (ambient) and the rela-
tively large particle size make cyclone collectors and fabric filters effec-
tive. A variety of these devices has been installed, ranging from single
large diameter cyclones to reverse-air fabric filters. Screens have also
been used for such unique applications as reducing the emission of large
sized particles (beeswing) from grain drying operations.
In the following sections, the technical characteristics of the various
types of control devices suitable for use on emission sources in grain process-
ing operations are discussed. In the section on p. 292 (Currently Used Control
Systems), the specific devices and process modifications suitable for reducing
emissions are reviewed for each emission source.
Inertial Separators - Collectors which rely upon particle inertia to separate
particulate matter from the carrier gas stream range from simple settling
chambers to relatively sophisticated cyclones. Because of the large mass mean
diameter of grain dust, these units are capable of medium to high collection
efficiencies. However, even the most efficient units normally operate with at
least some visible emissions.
Inertial collectors can be grouped into three board categories: settl-
ing chambers; cyclones; and impeller collectors. These units, and their
operating and design characteristics, are described in the following sections.
Settling chambers - Settling chambers rely solely upon gravitational
force to separate the particles from the carrier gas stream. Figure 30 is a
schematic of a typical expansion chamber. Particles are removed from the
carrier gas stream when their settling velocities are high enough (i.e., the
particles have sufficient mass) such that they settle out of the gas stream
in a period of time less than the residence time of the carrier gas in the
settling chamber. The carrier gas velocity must be low enough to achieve the
desired particle settling and also to prevent reentrainment of the settled
particles. These velocities are usually in the range of 1 to 10 ft/sec..£'
Physical limitations on the size of the settling chamber set the lower limits
on this velocity. Most units are designed such that the collection efficiency
declines rapidly for particles smaller than 50 um in diameter. Overall collec-
tion efficiency is, of course, dependent upon the particle size distribution.
In the grain and feed industry, settling chambers are often used as
"grain traps" to remove the kernels of grain and large grain particles en-
trained at various dust pick-up points. These grain traps are located close
to the dust pick-up points so the recovered product can be returned to the
process and to minimize duct wear by reducing erosion. Settling chambers are
generally not used for air pollution control.
278
-------
Figure 30. Settling chamber.
Cyclones - Cyclones have been used extensively for controlling emissions
in the grain and feed industry. In the last 5 to 10 years, however, many
companies have been installing fabric filters on new sources which were for-
mally controlled only by cyclones and replacing existing cyclones with fabric
filters.
Although several relationships between cyclone performance and design
and operating parameters have been postulated, none is entirely satisfactory.
The variation in collection efficiency with several of these parameters is
shown in Table 155.
Table 155. CYCLONE DESIGN PARAMETER AND ITS EFFECT ON EFFICIENCY^/
Increase in Parameter
Particle size
Particle density
Inlet velocity
Cyclone body length
Number of gas revolutions in cyclone
Ratio of body diameter to exit duct
diameter
Gas viscosity
Cyclone diameter
Gas density
Effect on Efficiency
Increase
Increase
Increase
Increase
Increase
Increase
Decrease
Decrease
Decrease
279
-------
Cyclones are classified as either "high efficiency" or "high throughput.'
High efficiency cyclones are characterized by a narrow inlet opening, long
body length relative to body diameter, and a small outlet diameter relative
to the body diameter. Higher collection efficiencies result from the in-
creased energy expended due to the high inlet velocities. High throughput
cyclones have larger inlet openings and larger gas exits. Figure 31 illus-
trates the geometrical relationships for these types of cyclones. Pressure
drop through the low efficiency units is typically in the range of 0.5 to
2 in. of water, whereas the high efficiency unit operates with 3 to 5 in.
pressure drop.—'
fc! !
r\ , «
.j
High Efficiency Design
High Throughput Design
Figure 31. Cyclone dust collectors.
The low to medium efficiency cyclones are supplied by a variety of
vendors, ranging from sheet metal fabricators to established air pollution
control equipment manufacturers. Because of their low cost and maintenance
requirements, they have been used extensively to control grain receiving and
shipping operations, as well as a variety of grain processing emission
sources. Collection efficiency for a properly operated and designed unit
collecting grain dust may reach 95%. For units which are not properly main-
tained (e.g., dust accumulations on the walls, air infiltration through the
dust discharge), the efficiency will decrease dramatically. Visible emis-
sions can be quite noticeable even for the best operating units.
280
-------
Collection efficiencies of high efficiency cyclones used on pneumatic
conveying systems for grain, feed ingredients, and milled grain of about 997o
have been reported.—' With the exception of flour mill systems, the units
can normally operate with minimum visible emissions; however, significant
visible emissions can occur if a dusty load of grain is received.
Figure 32 shows the typical collection efficiency for both the high
throughput and high efficiency cyclones for various particle diameters.—
Since both types of devices are inefficient for small particle collection,
and it is the smaller particles which scatter light most effectively, it is
apparent that even the most efficient cyclone will operate with some visible
emission if the incoming grain has a significant amount of fine dust or the
emission is from a process which has emissions with a small mass mean
diameter.
§ 80
CO
60
LLJ
I 0
Efficiency
High Throughput
10 20 !30 40! 50! 60i 70 ! 80
j III 1
— PARTICLE SIZE IN MICRONS-
: : i i !
400 325 270 250 200
— TYLER MESH —
90 100
170
Figure 32. Typical collection efficiency curves for high
throughput and high efficiency cyclones.
281
-------
A modification of the conventional high efficiency cyclone, shown in
Figure 33, recycles approximately 60% of the discharge air stream back into
the collector through a high energy blower in such a manner to induce a
swirling motion around the wall.—' The introduction of this recycle stream
through the high energy jets increases the unit's collection efficiency and
forms an air blanket around the inside wall which enables the unit to handle
higher moisture content streams.
Exhaust (Clean Gas)
•Inlet (Dirty Gas)
Secondary Air Pressure
Maintains High
Centrifugal Action
Secondary Air Flow
Creates Downward Spiral
of Dust and Protects
Outer Walls from Abrasion
Dust is Separated from
Gas by Centrifugal Force,
is Thrown Toward Outer Wall
and into Downward Spiral
Falling Dust is Deposited
in Hopper
Figure 33. Recirculating cyclonic collector.—
8/
This unit, the Aerodyne Type S collector, has operated satisfactorily
on several types of process dryers. It has also been used to a limited
extent on grain receiving operations where its efficiency has been estimated
to be about 997». However, as with other inertial collectors, the unit does
not eliminate visible emissions resulting from handling grain with a high
percentage of field dirt.
282
-------
Impeller collector - Figure 34 illustrates the impeller collector.—
The advantage of this unit is that it combines the functions of the exhauster
(blower) and the dust collector. The dust laden gas stream enters at the
central part of the impeller, and the centrifugal force imparted to the par-
ticles forces them into the collection hopper below the unit.
Clean Air
Outlet
Figure 34. Impeller collector.
These units are used to a limited extent on both grain handling and
process sources. Properly operated urits are estimated to have collection
efficiencies of approximately 9570 although definitive test data are not
available. The units operating on emission sources involving grain handling
usually have a visible discharge.
Fabric Filters - Fabric filters have been used to control essentially every
kind of emission source involving grain handling as well as several grain
processing emission sources. The only grain industry sources where they
are not used is where the effluent has a high moisture content and where
there is a chance of contaminating the recovered product (e.g., pneumatic
system which conveys many different types of feed ingredients). Industry
sources indicate that operational problems have occurred with fabric filter
systems installed on receiving pits when wet corn is unloaded. Blinding of
the fabric occurs because of the moisture content of the dust.
Cloth fabric filters - A number of particle collection mechanisms cause
dust collection in a fabric filter system. These mechanisms include inter-
ception, impingement, diffusion and to some extent electrostatic forces.
These forces and their effect on particle collection have been the subject of
283
-------
9/
considerable study.— Theoretical equations have been developed to predict
the pressure drop across the filter and the filter cake but they too are not
adequate for use in designing systems. Thus, the design of fabric filter
systems depends largely upon the experience gained from previous installa-
tions and observations of existing systems.
Fabric filtering systems can be classified in two ways. First is the
shape of the filtering surface, either tubular or envelope. The second
classification method is by type of bag cleaning mechanism, either mechanical
or reverse air flow. Figure 35 illustrates these basic shapes and the possi-
ble configurations of air flow through the filter.—'
Depending on arrangement, dust may be collected either inside the bag
or outside. In the latter case, some type of frame retainer is required to
hold the bag in shape* Another classification often used is "low-ratio" vs.
"high ratio," referring to the cubic feet per minute of air per square foot of
media. Low ratio filters are generally characterized by a simple cleaning
mechanism that does not remove all the dust from the bags, but excessive air
flow resistance is prevented by using a large number of bags that maintain
velocity through the media less than approximately 3 ft/min. Low ratio fil-
ters normally use woven cloth media and rely on the layer of dust (referred
to as "dust cake") to reduce the loss of fine dust particles through the
small openings between the threads. On the other hand, high ratio filters
use more effective systems for cleaning permitting the use of felted media in
which the layers of fibers overlay each other, so the passage of most fine
particles is prevented without the dust cake. A reduction in the thickness
of the dust cake permits higher velocity air flow through the media without
excessive resistance, usually in a range between 6 to 20 ft/min (typically
around 10 ft/min for grain dust).—'
Most new filters are using some method of flow reversal for cleaning
since shaker cleaning mechanisms necessitate the use of lower air-to-cloth
ratios and have higher maintenance costs. Air flow reversal methods include
forcing the dust cake off of the fabric with back pressure; collapsing the
cloth with associated flexure and cracking of the dust cake; snapping the
cake off with a pulse of compressed air; and blowing it off with an air jet
which traverses the outside surface of the cloth.— One common system uses
a blower to provide the reverse air for cleaning one bank of filter tubes at
a time. This device is sometimes augmented by the compressed air shock as
mentioned above, but in several installations this cleaning method has led to
fabric blinding because of moisture in the compressed air supply.
The air-to-cloth ratio, sometimes referred to as filter rate, is one of
the key design parameters for fabric filters. The ratios are customarily
selected on the basis of past experience and consideration of the nature of
the operation and the geographical location. For example, high ratios can
284
-------
Envelope or Frame Type
Up, Down, or Through Flow
-Cylindrical Types-
Outside
Filtering
Normal
(Upward )
Flow
L
Inside
Filtering
L
\
^ ;
d v^-—^
*™1
Down
Flow
\
s
N
,
MB
*
/
I
\
1
1
r-
e J
— ^
N
i
\
1
\
^
'A.
^
(Tube Type)
Figure 35. Fabric filter configurations.
285
-------
be used on grain handling sources because of the intermittent nature of the
operation, whereas in continuous grain milling operations, lower ratios are
normally specified. In humid areas, such as the Gulf Coast, lower ratios
are used because of the increased possibility of fabric blinding.
Cotton sateen, wool felt and dacron felt have all been used as filter
fabrics for grain industry emission sources..2.' However, dacron felt is the
fabric now recommended by essentially all of the filter manufacturers for
fy
these sources. Fabric weights between 16 and 22 oz/ydz are typically speci-
fied with the heavier weights recommended to minimize dust bleed through.
Bag life is on the order of 18 to 36 months, and varies with the type
of cleaning cycle. A complete cleaning of the bags (i.e., dry cleaning)
is sometimes required to restore their original efficiency and operating
characteristics. Complete cleaning of the bags would occur about once or
twice a year in a plant with a good preventive maintenance program.
Fabric filters, when properly designed and operated, operate relatively
trouble-free with efficiencies in excess of 99.9% and with no visible
emissions.
Glass mat filters - A fabric filtration device with a high pressure drop
has recently been introduced for controlling sticky particulate matter. The
operation of this device is illustrated in Figure 36.—Although this device
is not currently used for grain and feed emission sources, it might be suitable
for controlling emissions from such difficult sources as feed dryers in wet
corn milling.
Solid and liquid particulate matter is removed from the gas stream as
they pass through the blanket of glass fiber material. The glass fiber mat
uncoils from a spool, passes over a metal perforated drum, returns to a re-
wind spool and is then disposed of. The filter mat can be manually advanced
or automatically advanced at a predetermined rate.
The filter mat can vary between 0.03 in. and 1.5 in. in thickness with
densities between 0.6 and 8 Ib/ft^. The glass fiber mats are bonded with
a phenol formaldehyde resin. Other fiber materials can also be used. Fil-
tering velocities are generally in the range of 200 to 700 ft/min with pressure
drops between 6 and 25 in. of water. Collection efficiency increases with
filtering velocity, and hence pressure drop. Tests on nongrain industry
sources have indicated efficiencies in the 96% to 98% range.
286
-------
Dirty Air
Clean Air
Retaining Screen
Clean Mat
Dirty Mat
Figure 36.
Glass mat filter.-^/
High velocity filters - Another type of high velocity fabric filter re-
cently introduced is illustrated in Figure 37. This unit has been evaluated
for use on controlling truck dumps and is recommended by one grain dryer manu-
facturer for use on their grain dryer. Recommended filter velocities gen-
erally range from 400 to 500 ft/min. Pressure drops vary between 0.3 and 0.9
(clean media) to 0.5 and 1.5 in. of water during routine operation depending
upon the type of media and filter velocity. Typical media are 230 mesh
woven nylon, nonwoven polyester and nonwoven rayon felt. Test efficiency
data are not available but the manufacturer states that it is about 85% to
9770 efficient depending upon the particle size distribution, type of media
and filtration velocity.
The exhaust stream from the vacuum head is about 3% to 5% of the total
effluent, and the stream can be exhausted through a small fabric filter or
cyclone, or in the case of a grain dryer, through the dryer.
Screen filters - Screen systems are used to control beeswings and other
particulate matter from grain dryers. The collection mechanisms and operat-
ing principles are essentially the same as for fabric filtration, but the
larger mesh size enables high moisture content streams to be handled without
fabric blinding. Because of this larger mesh, however, screen systems are
suitable only for particulate emission streams which have large mass mean
diameter.
287
-------
Vacuum Manifold
Figure 37. High velocity filter.
There are three basic types of screen systems, namely screen houses,
rotary self-cleaning screens and sliding bar self-cleaning screens. These
units vary in physical configuration which in turn affects the filtering
velocity, and the method of removing the collected particulate matter. The
mesh size and material also vary for the different types.
There are two types of screen houses, settling and concentrating. In
the concentrating unit, an attempt is made to induce a flow pattern which
will concentrate the beeswings and other particulate matter into a selected
cleaning area where a vacuum head will remove the material. The vacuum
system capacity is about 10% of the total dryer discharge. The beeswings
concentrated in this system are collected in a higher efficiency cyclone or
filtered back through the dryer. These units are hard to design and outside
wind currents can disrupt the flow patterns.
Settling screen houses are cleaned manually. Thus, although they have
low initial capital requirements, the operating labor costs may be relatively
high. The wire mesh size is typically 24, 35, or 50 mesh. Pressure drops
through the screen house are nominal.
288
-------
Outlet loadings are hard to measure, at best, and vary due to the
variable characteristics of the grain. Also, if the grain is cleaned before
being dried, visible emission from the screen house will be reduced.
The rotary screen control systems can be either located at ground level
or elevated. Emissions from the dryer are vented through circular screens
between 5 and 14 ft in diameter. The screen is continuously vacuumed by a
rotary unit whose capacity equals about 1070 of the dryer discharge air. The
beeswings collected in this 107o stream can be recovered in a high efficiency
cyclone.
The wire screen is usually 34 to 100 mesh. Pressure drops are less than
1 in. of water during operation. Filtering velocities range up to 1,000 ft/min
but about 650 ft/min is usually the recommended value since the higher filter-
ing velocities can lead to blinding and higher pressure drops. In order to
eliminate blinding, some installations have increased the distance between the
rotary cleaning arm and the screen, but this has usually led to increased and
unacceptable screen maintenance.
In the sliding bar self-cleaning screen, the dryer emissions are vented
through screens mounted on long vertical panels. The unit is attached to the
dryer exhaust. The screens are cleaned by a vacuum head which traverses the
screen surface. The vacuum stream, which is about 10% of the total dryer
discharge, is exhausted through a high efficiency cyclone or recycled back
through the dryer.
The screen is usually made of 100 mesh dacron. As with the other screen
units, high moisture content does not impair operation because the cleaning
bar vacuum causes the dacron to "pucker" thereby effecting the higher degree
of cleaning needed for the finer mesh screen.
The pressure drop across the unit is about 0.5 in. of water. Filtering
velocities are between about 250 and 300 ft/min. Since these units are
mounted on the dryer discharge, the high efficiency cyclone used for removing
the collected beeswings and particulate matter is located between the dryer
discharge and the filtering surface. Placement of cyclone between the dryer
discharge and the filtering surface, helps to minimize problems with rotary
lock freezing on the cyclones, which can occur during cold weather. The
unit is guaranteed to remove 957» of all particles greater than 50 um in
diameter and normally operates without visible emissions.
Wet Scrubber - Wet scrubbers have been used to control sulfur dioxide emis-
sions from corn wet steeping, odor control in feed manufacture, and control
of particulates from high moisture content discharge streams. Their use has
been limited to such special applications for the following reasons:
289
-------
Particulates are the only emissions of concern from most sources.
If a level of control higher than that attainable by a cyclone is required, a
fabric filter can usually be used;
The material collected by a wet scrubber is rarely suited for
reuse in the process; and
Use of a wet scrubber requires treatment of the scrubbing liquor
effluent to prevent water pollution and sanitation problems.
The wet scrubbers used on grain processing emission sources can be broadly
categorized according to the following types:
Spray chambers
Venturi
Packed tower (included fluidized and turbulent bed)
Spray chambers - Spray chambers are simply a cylinder with sprays located
at the top of the unit. The gas flow can be either countercurrent or cocurrent
with liquid flow. Pressure drops are in the range of 2 to 5 in. of water with
the usual scrubbing liquor consumption of about 4 gal/1,000 ft . This type
of device is rarely used solely for gaseous control because of its relatively
low efficiency but occasionally is used for simultaneous gas and particulate
removal.
Venturi scrubbers - There are two general types of venturi scrubbers.
The first utilizes a high velocity gas stream in the throat of a venturi to
disintegrate the liquid and expose it to contact with the gas stream. The
other type, referred to as an ejector venturi, relies on a high velocity
liquid stream to provide the required mixing power. Because of the limited
contact time in these units, the unit is not efficient for gaseous pollutant
removal. The unit is effective for particulate removal although relatively
high power inputs are required. Pressure drops of 15 to 40 in. of water are
not uncommon with this unit. Liquid requirements range from 5 to 7 gal/1,000
ft3 of gas treated.H/
Venturi scrubbers are rarely used for control of grain handling emission
sources because control devices with lower overall costs operate satisfactorily
and do not have the attendant water pollution problems. However, for some
grain processing sources where fine particulates are emitted in a high moisture
content gas stream such as feed dryers in wet corn milling, this device may be
suitable.
Packed bed scrubbers - Packed bed scrubbers are used to provide suffi-
cient contact between the scrubbing liquor and effluent gas stream to effect
290
-------
gaseous pollutant removal. There are three basic types of packed towers,
namely fixed, fluidized, and turbulent bed. The selection of a particular
type of packed tower depends upon the characteristics of the emission stream.
Because of the potential for plugging the scrubber, fixed bed scrubbers are
normally used strictly for gaseous pollutant removal where there is only a
very light particulate loading. The fluid bed scrubbers, which use high den-
sity spheres for packing material, have only found limited use.
Turbulent bed scrubbers, which use low density spheres, are not sus-
ceptible to plugging because of the intense motion of the packing media.
The packing media move freely between the upper and lower retaining grids.
Under the influence of countercurrent gas and liquid flow the spheres are
forced upward in a random, turbulent motion, creating an area of intimate
mixing between gas and liquid. This type of scrubber is especially useful
when particulate matter is also present in the gas stream, since the turbu-
lent motion of the spheres prevents plugging. Typical liquid-to-gas ratios
are 2 to 4 gal. of water per 1,000 ft with pressure drops in the range of 6
to 8 in. of water. This unit operates with particulate collection efficien-
cies of about 997o for particles with a mass mean diameter larger than 2 urn.
Afterburners - Afterburners can be used for control of combustible particu-
lates and odors. Although they have been identified as suitable for use on
such sources as feed dryers in wet corn milling and in animal feed manufac-
ture, there is only one known installation in use. The known afterburner
installation is on a suspension dryer at the St. Lawrence Starch Company
at Port Credit, Ontario.
There are two basic types of afterburners, thermal and catalytic. The
thermal afterburners use direct flame incineration and operate at higher
temperatures than do the catalytic units. Thus, they require more fuel.
Minimum required temperatures and residence times are usually specified
for thermal afterburners to effectively oxidize the pollutants. They are
usually in the range of 1200-1800°F and 0.3-0.6 sec depending upon the char-
acteristics of the emissions.
The main advantages of the thermal afterburner are the high degree of
removal efficiency for submicron sized combustible particulates, the ability
to control both gaseous and combustible particulate pollutants and the low
maintenance requirements. The primary disadvantage is, of course, the high
fuel requirements which mean high operating costs. Heat recovery is usually
necessary to have acceptable operating costs. Furthermore, afterburners will
only remove combustible particulate, not mineral particulate. Thus, it may
be necessary to use the afterburner in conjunction with some type of high
energy mechanical collector or other particulate control device.
There are processes where direct flame incineration can be accomplished
by using the effluent from a process as combustion air. An example of such
291
-------
an application is using the exhaust from a feed dryer as part of the combus-
tion air. Careful consideration must be given in the design of such systems
to avoid possible explosions or complications with the combustion process.
CURRENTLY USED CONTROL SYSTEMS
The section on p. 275 Dust Control Systems, described the general types
of control equipment either in use or suitable for use on grain handling
and processing sources. In this section, additional information on those
systems, or process modifications to reduce emissions, which was not rele-
vant to the previous general discussion, is presented.
Table 156 lists the types of devices which are applicable to the vari-
ous emission sources, their approximate collection efficiencies, and outlet
grain loading. Only those devices which are either currently used or appear
suitable for use are listed. Devices which may be capable of attaining
equivalent collection efficiencies but which have definite limitations (e.g.,
water pollution potential) with respect to other devices capable of satis-
factorily controlling emissions for that source are not discussed. The
collection efficiency and outlet grain loading data are primarily based upon
the source test results described in Chapter 3. However, for many sources
it was not possible to quantitatively describe collection efficiency due
to the general lack of test data. In such cases, collection efficiencies
have been estimated based upon the performance of these control systems on
similar emission sources. Some of the more important dust sources and con-
trol methods used on the sources in various segments of the grain and feed
industry are discussed in the following sections.
Grain Handling Operations
Many grain handling operations can be modified to contain the dust which
is normally emitted. Examples of these modifications are listed in Table 157.
Cyclones and fabric filters are used almost exclusively to control
emissions from grain handling operations. The use of cyclones has been
declining because of tightening environmental regulations, especially with
regard to visible emission regulations since properly designed cyclones
can usually meet existing process weight type regulations.
Because of product value, cyclones on pneumatic conveying operations
generally operate with efficiencies in excess of 99%. These units can
operate with essentially zero visible emission except when handling very
dusty materials. In some cases, product recovery cyclones are followed
by fabric filters for emission control purposes.
292
-------
Table 156. AIR POLLUTION CONTROL DEVICES USED
IN THE GRAIN PROCESSING INDUSTRY
Operation
1.0 ELEVATORS
1.1 Grain receiving
Control Device
Cyclone
High energy, recirculating
High velocity filter
Fabric filter
Applicable Control Devices
Collection
Efficiency
Range
85-95
cyclone 97-99
95-99
99 +
Typical Outlet
Loading Range
(gr/scf)
0.02-0.09
0.005
0.002-0.006
1.2 Grain drying
Screen house
Rotary screen - self cleaning
Vertical screen - self cleaning
1.3 Transfer operations
1.4 Shipping
2.0 FEED MILLS
2.1 Receiving
Same as grain receiving
Same as grain receiving
See grain receiving operations
for elevators.
2.2 Grinding system
Product recovery cyclone 99
(Pneumatic conveying from grinder)
Fabric filter 99
0.01-0.0
2.3 Pellet cooler
Cyclone
low energy
medium to high energy
88-965'
98-99^
0.02-0.7-
a/
0.06-O.LS
a/
2.4 Shipping
3.0 ALFALFA DEHYDRATING
3.1 Dryer
3.2 Hammermill
See shipping operations for elevators
Cyclone 85-98
Wet scrubber 21-92-'
Cyclone 85-98
Fabric filter 99 +
0.10-0.30^
0.02-0.095/
0.60-1. b-
3.3 Pellet mill
3.4 Pellet cooler
Cyclone
Fabric filter
Cyclone
Fabric filter
85-98
99+
85-98
99+
0.09-0.24S7
4.0 MILLING
4.1 Receiving
for elevators
operation
4.2 Cleaning house
Cyclones
Fabric filter
88-99-
99 +£/
0.03-0.1^'
0.005-0.02^
4.3 Mill house
Cyclone
Fabric filter
0.04-0.2
0.005-0.01-'
4.4 By-Products
Hammermi11
Cyclone
95 -99-2.'
0.1-2.0
293
-------
Table 156. (Continued)
Applicable Control Devices
4.5 Shipping
by-products
Flour
5.0 SOYBEAN PROCESSING
5.1 Receiving
5.2 Drying
5.3 Processing
. Cracking mills
. Dehulling, condi-
tioning, flaking,
cooling, and toasting
. Meal drying
. Meal grinding
5.4 Shipping
Control Device
Cyclone
Fabric filter
Fabric filter
See grain receiving operations
for elevators
Screen house
Vertical self-cleaning screen
Fabric filter
Cyclone
Cyclone
Wet scrubber
Fabric filter
Cyclone
See shipping operations for
elevators
Collection Typical Outlet
Efficiency Loading Range
Range (gr/scr)
99+
99+
99+
99+
9S-99-/
88.7-99
99+
99+
98-99-'
0.02-0.05^'
0.008^'
6.0 WET CORN MILLING
6.1 Receiving
6.2 Drying
6.3 Steeping
6.4 Germ and gluten
Drying and cooling
and feed and pellet
cooling
6*5 Feed drying
6.6 Feed house aspiration;
transfer of germ, gluten,
feed, and starch; and
starch drying
6,7 Carbon regeneration
furnace
6.8 Corn syrup solids
drying
6.9 Product loading
See grain receiving operations for
elevators
See drying operations for elevators
Packed bed scrubbers 90-99+ for
S02 control
Medium energy cyclones 80-95
High energy cyclones 95-98
High energy cyclone 95-98
High energy scrubber 98-99
Afterburner 99+
Low to high energy cyclone 85-98
Fabric filter 99+
Wet scrubber (starch drying only) 95-99
Afterburner
Low to high energy cyclone 85-98
Wet scrubber 99+
See grain loading operations for
elevators
0.145^
0.145s'
294
-------
•t)
T3
3
i— i
CJ
c
O
O
^^
.
v£>
t/^
r-l
CU
^
CO
H
en
CU
0
•H
01
Q
r-H
O
^!
4-1
C
O
o
01
rfl
CO
0
• H
I—I
a
o.
*"
4-1
0)
r-l
4-1
3
O
r-l
CO
o
•rl
P.
[>i
H
d
o
•rl
4-1
CJ
01
t—l
r-l
o
U
c
o
4-1
ra
rl
Ol
a
o
Q)
60
d
to
03
60
C
•a
cfl
o
>>
CJ
a
o
•H
0
•rl
4-1
14-1
w
y~*
4-1
O
-~.
60
^-*
Ol
w
d
CO
«
en
d
o
4J
CO
j_i
CU
a
o
60
cu
u
•H
cu
Q
I— 1
o
4J
C
O
o
c
•r-l
>
01
o
cu
J_J
CJ
•rl
CO
00
0)
0)
en
o
z
M
, ")
, ")
M
g
w
u
H
OJ
60
d
•rl
•H
CU
a
0)
oJ
O r-l
en
rl
O
4J
CO
01
t — 1
01
^1
o
4-1
00
ON
1 +
u"l C7N
00 C^
en
O
co O
> 4-1
01
r-l CO
Ol B
O
U -rl
O 4J
M-l CO
J^
CO CU
c a.
0 0
•H
4J bO
CO C
CU T3
(X rl CO
o a) o
4-1 r-l
60 --I
d -i-i C co
•rl 4-1 -rl IJ
>, 01 CO O
rl C U Vj 4J
T3 O -i-l 60 CS
r-l H >
Ol O XJ Ol 01
0) >> to 01 r—l
en o fu en cu
en
l-i
CU rH
>, r-l 3
•a 43
CO T3
CX « C
en eg
1 rl
CO O "CO
ti 4J CO M 60
60 CU CO CU CU fi
d >-i ri 43 "O i-l
•H r-l CO CO C T3
>x, Ol d, 3 -rl flj
rl 43 Ol rl U O
Q CO CO XI 60 r3
CN CO -^J"
.
in
•a
o
43
4J
Ol
s
^2
p-l
ty
to"
CO
T3
4-1
CO
01
4-1
^
CJ
CO
4J
CO
r-l
CO
3
4-J
O
CO
e
o
M
"«!
295
-------
Table 157. PROCESS MODIFICATIONS USED TO REDUCE DUST EMISSIONS
FROM GRAIN HANDLING OPERATIONS
1. Close at least one door in unloading areas (three sides closed).
An air suction across or through the grating is necessary.
2. For loading hopper cars or bulk trucks and ships, a secondary pipe
may be installed next to the feed discharge pipe to pick up the
airborne dust. Minimize the area of opening by use of tarps or
other covers.
3. Telescoping loading spouts to reduce free fall distance of grain.
4. Use closed mechanical conveyors and processing systems.
5. Intervent the scale hopper, mixer and surge hopper.
6. Intervent the up and down leg of the bucket elevator.
7. Pressurize the processing building to contain dust inside the con-
veying and processing equipment (usually economical only if
included in initial design).
8. Seal the materials handling system as tightly as possible; apply a
slight vacuum to entire system with suction air routed to a collector.
9. Intervent two or more storage bins. (Insurance companies may not per-
mit interventing all storage bins).
10. Utilize choke unloading of hopper cars.
11. Install louvers under grating of unloading operations which open when
grain falls on the louver. This reduces the volume of air which must
be aspirated through the grating.
12. Utilize drag conveyors in place of belt conveyors where feasible.
296
-------
Cyclones which are used purely for air pollution control are usually de-
signed for much lower efficiencies. The general lack of maintenance given
many of these units further degrades their performance. Typical efficiencies
for such units are between 85% and 95%. Visible emissions can range up to
30% or 40% equivalent opacity, again depending upon the nature and type of
material being transferred or handled.
High energy recycling cyclones have also been used to a limited extent
to control emissions from truck dumps. Although the weight percent collec-
tion efficiency is high, visible emissions occur when grain with large
amounts of field dust are received.
Fabric filters are the most efficient devices for controlling emissions
from these sources, operating with collection efficiencies in excess of
99% and with no visible emissions. Air to cloth ratios on filters for most
grain handling emission sources are usually between 10 and 15 cfm/ft^ of
cloth, with the higher ratios used in dry climates and on intermittent opera-
tions where there is less chance of fabric blinding. Newer systems with more
effective fabric cleaning are purported to be operating with air to cloth
ratios of 20 to 30.^
Spokesmen for the grain and feed industry have indicated that operational
problems occur with fabric filter systems on grain receiving pits when wet
grain is unloaded. Corn with a high moisture content poses a distinct
problem. Blinding of the fabric filter by the wet dust has created numerous
cases of equipment malfunctions.
Specific dust control systems for various grain handling operations are
discussed in more detail in the following sections.
Grain Receiving and Shipping - The grain receiving and shipping areas repre-
sent a difficult dust control problem. The two principal factors that con-
tribute to dust generation during bulk unloading and loading are wind currents
and dust generated when a falling stream of grain strikes the receiving pit.
Capture or containment of the dust is the most difficult problem encountered
in receiving and shipping operations.
Truck unloading - Effective control of the dust emitted during truck un-
loading operations generally requires the use of undergrate aspiration and a
suitable enclosure or shed over the receiving pit. The undergrate aspiration
prevents the upflow of air out of the grate and the enclosure minimizes the
influence of wind currents. The aspirated air is directed to a control de-
vice--generally a cyclone or fabric filter.
The undergrate aspiration system is often designed on the basis of a
minimum of 100 ft/min face velocity/ft^ through the grate.* Therefore, a
* Some consultants recommend that a minimum of 200 ft/min be used.
297
-------
o
grate having dimensions of 10 ft x 10 ft would contain 100 ft , requiring
an airflow of 10,000 cfm. Considering the wind velocity that often exists
in the drive-through tunnel or a shed with no rear door, the face velocity
of 100 ft/min may not provide sufficient capture of the emissions. However,
the capture can be improved without increasing the airflow rate. Improved
capture is accomplished by installing louvres underneath the grate. These
louvres restrict the flow of air but swing open under the weight of the
grain and allow it to pass through into the receiving hopper. This configura-
tion results in maximum airflow at higher velocities near the grain stream
which, in turn, provides improved capture of the dust.
A different type of truck unloading dust control system was reported
in Reference 12. The system was installed on a 600-bu truck dump pit,
and utilized a swing-away hood at one end of the pit behind the truck. The
hood covered the last 2 ft across the width of the grating and exhausted
16,500 cfm to a fabric filter. A capture efficiency of 957=, to 97% was re-
ported.
Boxcar unloading - The most common boxcar unloading method consists
first of breaking the grain door inside the car, which produces a surge of
grain and dust as the grain falls into the receiving hopper. After the
initial surge of grain, the remaining grain is scooped out of the car using
power shovels, a bobcat or some similar means. A surge of dust accompanies
each scoop of grain as it strikes the receiving pit.
The other common boxcar unloading technique, used mainly by terminal
elevators, is a mechanical car dump which clamps the car to a movable sec-
tion of track and rotates and tilts the car to dump the grain out of the
car door into a receiving pit. This is a rapid unloading method that creates
a large surge of dust in a manner which makes it difficult to efficiently cap-
ture the emissions.
Undergrate aspiration can be applied to the first unloading method, and
will reduce emissions, but large volumes of air are necessary to provide high
capture efficiency. A typical railcar unloading system might handle 35,000
to 50,000 bu/hr which would require undergrate aspiration of about 20,000 to
25,000 cfm. Aspiration from the belt loading below the hopper would be 800
to 1,000 cfm and at the belt discharge it would be about 1,000 to 2,000 cfm.
In addition to undergrate aspiration, some elevators have installed
aspiration panels near the car door in an attempt to capture the dust
emissions. This method is considerably more effective if a flexible closure
is used as shown in Figure 38. This can be reasonably effective even when
the unloading area is not enclosed.
298
-------
BUILDING
LINE
UNLOADING
DEVICE
ENCLOSURE -
GRATE
CONVEYOR
/
e^
9,000 TO 15,000 CFM
•CLOTH FILTER
ROTARY
• VALVE
LEAKS - 2,000
TO 5,000 CFM
7,000 TO
10,000 CFM
IN DOOR
tJ
FLEXIBLE CLOSURE
HOPPER
Figure 38. Boxcar unloading dust control system.
299
-------
The mechanical car dump presents a more difficult dust control problem.
Undergrate aspiration has been used to reduce the emission. Aspiration
panels near the door have also been used, but their utility is restricted
due to clearances necessary for rotation and tilting of the car. Aspiration
ducts located at each end of the dump pit have also been used.
Hopper car unloading - Control of dust emissions during unloading of
hopper cars has been accomplished by using two methods. The first of these
uses undergrate aspiration similar to that for truck unloading, except that
the grate area is usually smaller and therefore requires correspondingly
smaller airflow. The second control method is based on the use of a small
receiving hopper to effect choke unloading. With this method, there is a
momentary surge of dust as the receiving hopper fills, but very little dust
is generated during the remainder of the unloading operation. This unload-
ing method does eliminate the need for air aspiration and a collector, but
there would be some expense involved in modifying an existing unloading
facility.
Truck loading - Most truck loading operations involve the free-fall, of
grain into the truck with considerable emission of dust. The quantity of
dust is less when using choke loading, by means of a telescoping spout or
when a slide valve or other flow control mechanism is used to restrict the
flow of grain to reduce the velocity at which it leaves the spout.
The control of the dust emissions from truck loading is difficult due
to the variations in the sizes of the trucks and required movement of the
loading spout. At many terminal elevators the truck loading operation is
covered and enclosed on two sides and a few of these have aspiration ducts
inside this area, but capture efficiency is hampered by the wind-tunnel
effect.
It may be possible to install a shroud, with aspiration, that covers
the top of the truck, but the different sizes of trucks, and the need for
the operator to observe the loading, may make this method impractical.
However, such a system has been used successfully for hopper car loading.
Choke loading may also be used, wherein the grain does not free-fall
into the car or truck but instead is restricted by the accumulated grain
load or pile by means of a telescoping spout. This loading method does
help to reduce the emissions, but may not provide sufficient reduction in
the emissions for air pollution control purposes.
It would be possible, of course, to use doors at both ends of the un-
loading enclosure and evacuate the air from the enclosed area to a collector.
However, the doors hamper movement of trucks and no elevators are known to
use this method.
300
-------
Boxcar loading - Two methods of controlling the dust emission from box-
car loading have been used, although they have infrequently been applied.
The first method consists of covering the car door with some material and
aspirating the air from inside the car to a suitable collector (usually a
fabric filter). The second method consists of an aspiration system located
near the car door. This second method is not as effective as the first,
but it allows the operator to observe and adjust the spout during loading
operations. A sketch of one such system is shown in Figure 39.
Hopper car loading - The methods used to load hopper cars and to con-
trol the associated dust emissions are similar to those used for trucks
and the loading may be done in an enclosed area. One dust control method
that has been successfully used to control dust from hopper car loading
is shown in Figure 40. This consists of a shroud made of belting material
that encloses a portion of the top of the car to within a few inches of the
roofline. A second inner shroud encloses the loading spouts and approxi-
mately 9,000 cfm of air is aspirated from inside this inner shroud to a
control device. The inner shroud comes to within 1 to 2 ft of the roof of
the car which allows the operator to observe the loading and control the
flow of grain. This system appears to be quite effective and eliminates
the need for enclosing the loading area. Similar systems consisting of a
collection hood with flexible ducting have been designed to aspirate air
from the hopper car during loading.
Barge and ship loading - Barge or ship loading presents a difficult
dust control problem. The grain usually falls a considerable distance into
the holds which results in a cloud of dust. Containment of the dust without
interference with the loading process presents a challenge. The ship loader
consists of a belt conveyor discharging to a vertical duct that extends into
the ship's holds The loading duct may vary from one installation to another.
Some installations have a telescoping loader that can displace laterally
only, others provide full traverse; some raise the entry loading gantry;
some use an inclined loading boom that is emplaced after the ship is moored.
The telescoping feature allows for variation in tide, height of the ship,
1 Q /
and depth of material in the hold.—'
Most installations employ a slinger (trimmer) at the lower end of the
loading spout to insure proper distribution of the load and maximum utiliza-
tion of the cargo space. A trimmer is essentially a short (4 ft to 6 ft)
belt conveyor running at high speed (3,000 to 6,000 ft/min) whose function
is to "throw" the bulk material being loaded to those areas of the hold
distant from the loading spout (up to 60 ft) .±2-'
The fall of bulk material through a vertical loading spout acts as a
kind of linear fan inducing a flow of air into the hold,, The volume of this
induced air may be substantially greater than the air volume displaced by
301
-------
Loading Spout
Exhaust Duct
Exhaust Duct
Approx. 12" Clearance
Between Boxcar & Housing
Figure 39. Dust control system for boxcar loading.
302
-------
6
a)
•u
ra
>•,
ra
4J
c
o
J-l
CO
T)
so
C!
•i-l
"O
(0
O
Pu
s
00
•H
303
-------
the bulk material delivered into the hold. The high velocity "throw" of
the slinger at the bottom of the loading spout produces a "rooster tail" of
particles that are readily entrained in the induced and displaced air.
Voluminous clouds of dust escape from the ship's hold as the loading opera-
tion proceeds. Additionally, the vertically falling material hitting the
high speed horizontal belt of the slinger causes a bounce-back of particles
up the loading spout. This results in a boil-out of dust at the joints of
the telescoping loading spout. Some of this dust falls back into the hold
while the remaining portion adds to the dust cloud from the hold.
As in any problem of air pollution control, capture or containment of
the emission to be controlled is the first prerequisite to its removal.
It is this capture that is the most difficult problem encountered in bulk
loading of ships. Unlike a normal industrial operation, a bulk loading in-
stallation must serve ships of widely varying length, beam and hatch open-
ing dimensions. The ship's rigging and loading booms interfere with the
free space above the holds. The level of the deck rises and falls as the
height of the tide varies and as the loading changes the ship's trim.
The problem of ship loading dust control is compounded by the necessity
of developing techniques and methods for three basic and different ship con-
figurations: bulk carriers, tankers and 'tween deckers.—'
The bulk carrier is an empty hull compartmented by a series of vertical
bulkheads. Each hold seldom has any internal structures, i.e., wing decks,
or center bulkheads and thus no encumbrances are normally found which can
slow the loading operation (Figure 41). Hatch openings are generally large;
access to all parts of the hold is relatively easy.
The tankers used in grain transport are designed for movement of liquid
bulk. As such, the openings into any particular compartment or tank are
relatively small. Two types of hatches are common to tankers, the larger
"hard hat," about 3 ft in diameter, for major filling, and the smaller
Butterworth (normally 11 to 12 in. in diameter) used for filling the voids
(Figure 42). Occasionally "bulk carriers" have side or wing tanks with
Butterworths that are loaded in a similar manner.
'Tween deckers generally tend to be smaller and older than either
tankers or bulk carriers. Basically, the hold is similar to a bulk carrier
with the addition of usually two horizontal cargo decks. These have a large
opening in the center which may or may not be divided by crossbeams,
(Figure 43). In loading these ships, care must be taken to adequately stow
the grain under the intermediate decks. If all spaces are not properly
filled, i.e., trimmed, a shift in cargo could cause the ship to list or
capsize. Some of the newer type 'tween deckers have grates located in the
bulkheads that allow the grain to flow through and fill the void.
304
-------
BULK CARRIER
Hatch
Section
Hatch
Bulkhead
Deck Detail
Figure 41. Diagrammatic representation of a bulk carrier hold.
305
-------
TANKER
u-J
-Butterworth
-Hardhat
Section
Butterworth
Hardhat
Deck Detail
Figure 42. Diagrammatic representation of a tanker.
306
-------
'TWEEN DECKER
\
Hatch
r-Weep Hole
•fe
Section
-**-
—Beams
-Hatch
-Bulkhead
Deck Detail
Figure 43. Diagrammatic representation of a 'tween decker.
307
-------
Trimming is not required in these cases. The older type 'tween deckers re-
quire a feeder box that extends up from the lower hold and ensures that grain
can continue to fill the lower hold when the grain settles. This feeder box
makes it very difficult to load the upper portions of the hold since only a
3 to 4 ft opening exists around the outer
Any air pollution control system employed for ship loading must be
capable of capturing airstreams issuing from hatch openings varying from
10 ft x 20 ft to 50 ft x 90 ft; it must fit readily in the cluttered deck
space; it must allow for periodic observation of the progress of loading
so that adjustments in load placement can be made; it must not be exces-
sively difficult or time-consuming to put in place; it must withstand the
humid and corrosive harbor atmosphere; and it must operate on abrasive and
hygroscopic dusts. —
Currently, several techniques are employed for the control of ship
loading. Nearly all employ fabric filters as the control device but vary
their enclosure of the hatch being loaded or the way the loading spout is
positioned. Reference 13 presents a discussion of several techniques de-
veloped to control dust emissions from ship loading operations at the Ports
of Los Angeles and Long Beach in Los Angeles County. Table 158 summarizes
the pertinent features of these techniques.
Cargill, Inc., and the Port of Seattle have been engaged for about
2 years in an effort to develop a dust control system for the new grain
terminal on Elliott Bay in Seattle. M/ Their efforts have resulted in the
development of a quite successful procedure for controlling dust emissions
during ship loading. Since control of these emissions does present a signif
icant problem to export elevators, the key features of the system are high-
lighted in the following paragraphs.
Initially, a dust collection system rated at 20,000 cfm was installed
to remove the dust from the hold. In this design, air was to be drawn up
through the void in the loading spout; this would eliminate the need for
an auxiliary hose on deck. However, unforeseen problems hampered the dust
removal; as the grain flowed across the knuckle that allows vertical spout
movement; it would bounce from top to bottom of the spout and hinder the
reverse air supply. Bypassing the knuckle with a supplemental duct was
tried, however, such an arrangement failed to correct the problem. Sub-
sequently, a separate duct was attached to the top of the spout and ducted
back into it at the lower end, thus restoring the desired reverse airflow
(Figure 44). However, this arrangement was found to be inadequate to meet
the equivalent opacity standard requiring dust emissions not to exceed 40%
opacity, or Ringlemann II.
308
-------
CO
CU
CU
4-1
d
oblems encot
Q.
H
T3
O)
o
0
CU
d
o
Q
CU
4J
4-4
CJ
Q.
CU
•o
QJ
d
QJ
c
O
a
CO
CU
erse-
Q)
x
w
x:
4-1
M-l
M
4-1
cO
X
TD
CU
d
Q,
00
d
4-1
3
3
x
•o
CU
o
a
CU
cu
CU
D-
0
U)
4J
3
O
C
cci
O
CU
•o
00
c
•-1
CU
cO
4-J
co
capture of c
CU
s
co
•o
X
a.
co
4-1
O
n
QJ
x
1 '
o
0
Q.
"O
cfl
0
£
CU
-M
pproxi
0
3
O
SapTA
i-J
o
a
Q)
3
co
CU
3
0
£
0)
•l-l
4-J
CO
B
CJ
o
o
ON
>,
CU
.rH
w
CU
•H
•O
CO
O
d
c
cO
CU
O 4-1
CU 3 •
• S-i
CU O
3 QJ X
4J
D
•rH
§
4-J
P
O
4-1
O
O
H
•o
cO
o
g
"3
4-i
CO
O
O
CJ
1-1
C
O
a
0
d
ctive under
4-1
00
•H
CJ
3
T:
4J
3
cfl
X
X
o
4-1
d
O CU
4J
3 X
•> T3
> CU
S 1
S °
d
tfl
• o.
CO CD
d
•H ra
00
c
o B
f-i O
cO O
x
CU 00
to c
3 .H
0 -o
•Fj, ?
X
cu x:
X 4J
4-1
S o
co co
T3
CU X
3
•H
to
3
o
1
cu
CU
c
CU
d
cu
d
tO
3
a
M
e
cO
cu
0
4J
-C
en
TJ
O
i— i
a
o
QJ
*
CO
x:
CU
o
g.
M
°
U
a
4J
(0
cu
3
ffl
QJ
H
4_)
3
O
a-
loading
CU
-H
J2
ct(
x
4-1
3
QJ
CU
4-1
CO
o
CU
4J
in betweer
necti
n
en
-o
•tji
0.
CO
cfl
O
00
•H
tO
0
cu
M-l
••H
i
-a
cfl
0
c
(U
ca
a)
IH
Q
0
a
0
M-l
verti- c
CU
x:
en
M
T)
*
co
•rH
QJ
4-1
3
tJ
es excessive
3
n)
a.
en
QJ
O
4->
d
0
co
tO
(U
CL
C
i— i
o
(U
U
c
w
w
fe
I
D.
tO
exhau
ie system
•a
o
•o
CU
to
H
•H
X
(4-4
O
QJ
•rH
CO
•a
e
o
S
o
o
o
ffl
a
'«
M
m
1
4-1
S
•rH
X
W
S
CU
tO
n)
T3
O
to
•^
a.
cu ca
o >-,
QJ 4J
> o
CU QJ
techniques c
are not dil
CU !H
X CU
water
\
• co
•H
O co
*0 "S
OJ
0.
tw
3 co
0) X
i-l -H
co
•f-l
.rH
a
cO
cu
4-1
o
o
U
OJ
tO
cu
4J
CO
3
1
c
cO
w
cu
•r-t
J-
a.
X
g
CO
QJ
o
3
co
Q)
X
4-1
o
o
3
cu
4J
cO
J-l
d
cO
o
n/ton/hr
rH
IW
01
O
•U
3
O
a.
•H
cO
00
d
o
d
X
•o
CU
c
cO
CD
CJ
CO
•rH
QJ
co
3
cfl
X
a,
a
OJ
>,
V
cfl
CU
QJ
4-1
O
4-)
CU
3
•H
Cti
4-1
3
ca
4J
cu
rerse
CU
CU
4-1
CU
QJ
CL •
co cu
CU cO
i-t O
X rH
O
M O.
Q. -T-C
CU O
O
CU
CO
00
cO
CU
H
(0
CU
O CU
4-1
s
o
c
OJ
o
tO
Q.
CU
H
contrc
QJ
O
CU
O
•a
cO
e
N
U
X
4-1
Cfl
Q,
0
CU
C.
3
o
QJ
O
•o
CU
§
'D
CU
4J
tO
rH
CD
U
4-J
Cfl
CU
(U
o
cfl
TD
tO
0
a)
0
-D
arthest er
CU
4-1
w
>i
d
>
rH
-------
•-i •- c x:
4-1
C
3
CO
4-J
S
cn
4-1
x:
4-1
to
14
cO
d
a.
C
crease
ndraf
0)
•o
severely
TJ
0)
M
H
>,
H
V
QJ
—4
annot
•r-l
O
O
0)
indraft
QJ
>
co
w
QJ
01
x:
x:
O)
a.
Q
o
H
g
o
•£j
CO
x:
exposed
•H
01
1
•S
cn
QJ
4J
x!
O
M
O
Q.
QJ
S
01
4J
a
£
QJ
4-1
0)
•H
U
QJ
O
QJ
•H
operate^
portion
to
8
oT
0
g
o
4-)
x:
x:
4-1
x:
QJ
effecti\
3
cn
0.
O
«
enclosul
essur
a.
ti
00
a>
4J
o
(0
•a
QJ
•H
producec
QJ
O
a)
j=
cO
4_J
S,
o
m
n)
C
•rl
B
m
9
S
cd
nouette
CN
o
4-1
a.
QJ
a.
cn
1
0)
3
C
QJ
•H
M-l
W
knots .
CO
0
c
i
4-1
QJ
x:
to
o
00
T3
O
permits
4-1
c
§
a.
•i-i
T3
without
•H
•u
c
3
a.
loading
•H
r-i
"
£
closure
4-1
4-1
CO
S-i
0
4-J
'e
ns
a
o
OJ
CL
OJ
o
x:
H
CO
0
3
H
IW
designec
4-1
•H
O
QJ
3
CO
•o
o
0
bo
x:
o
U-l
s
3>
success
g
cO
•H
S
x: x: 3 x: -o
1-1 4J S 1-1 .
T-*
O
4-1
C
o
0
u
0)
tO
P-.
J-l
4-1
c
cO
bo
01
x;
4J
g
QJ
4-1
d
o
e
OJ
cd
•3
O
T— 1
c
QJ
J3
TD
0
Xi
XI
4J
3
cO
x:
0)
cn
3
4J
S
•O
a>
r-l
X
ra
•a
3
o
H
4-1
S
d
o
£
cO
QJ
QJ
C
cO
G
O
j-1
tj
'a
£
a.
M
4-1
>1
cn
4-1
d
cO
•5
,
w
to ,
•U
cO
B
o
o
CN
cn
QJ
S
O
o
1 cO
•r-4
4->
c
QJ
QJ
4-J
3
03
U
QJ
M
a.
x:
H
V4
QJ
u
to
x:
><:
a)
ffi
"I
tO
4-1
S
4-1
CCJ
cn
3
tO
Xl
a)
to
•a
•H
a.
•H
•o
co
o
^
x:
0
4-1
S
CJ
cn
QJ
>
O
y-i
0
cO
QJ
3
O
XI
cO
QJ
X!
H
4J
Cfl
a.
o
3
o
4-1
M
cO
0)
O)
•°
«
C
nj
QJ
U
cn
h
QJ
4O
CO
QJ
x:
a
o
o
s
4J
>.
T3
0
tO
1)
QJ
QJ
i
'M
01
xl
d
o
•H
tO
a
o
5
4-J
S*.
Xi
•o
CO
XI
cO
£
3
O
O
cfl
cn
C
0)
•D
g
a
C
-------
EXHAUST SYSTEM
Air in Spout
Hose Adapter
for Tanker
Figure 44. Diagrammatic representation of the existing air
exhaust system at Pier 86, Seattle, Washington.
311
-------
A major breakthrough in dust control occurred when attempts were made
to determine whether dust would be reduced when the spout was held very
close to the grain pile. It was found that the loading spout could be placed
4 to 6 in. into the grain pile without backup of grain in the loading spout.
By maintaining the spout in the grain 4 to 6 in., the grain had sufficient
energy to push out of the spout without dust generation. Following the
addition of the auxiliary duct on top of the grain loading spout (which by-
passes the restricting grain) and by drawing air up the void, the spout
could be held as far as 5 in. out of the grain and as much as 6 in. into the
grain without excessive dust emissions.
Using this and other new techniques, a system of loading has been de-
veloped that can accommodate 9570 of all grain loaded at the pier. Recom-
mended methods for various types of ships are summarized in the following
paragraphs. All the techniques listed below have been tested and with the
exception of trimming, have been shown to provide adequate dust control.
Bulk carriers and 'tween deckers - To develop techniques for these
ships, the loading operation was broken down into four main activities:
(1) start-up; (2) general filling; (3) trimming, and (4) topping.
Start-up - All ships (except tankers) can be started in the fol-
lowing manner: the loading spout can be extended to within 3 ft of the
bottom of the ship and pouring started at 1,200 tons/hr. This procedure
will build a pile sufficient to bury the spout in less than 2 min. In some
cases, as many as two, 10-ft extensions are needed to reach the bottom of
the ship. If the spout cannot be placed sufficiently close to the bottom,
an alternate method should be used. One method consists of inserting the
spout in the hatch, closing the hatch covers as far as practical, and
covering the remaining hole with tarps or plastic. A 10 ft x 10 ft hole
can be left open for visual inspection of the filling process. During this
time, sufficient air is being drawn up the spout and the incoming air
eliminates dust emissions. However, when the grain reaches the extended
spout it should be buried and the pile of grain moved around by this method.
These two methods will reduce emissions on all bulk carriers or general
cargo types of ships.
General filling - After the pile has been started, the general
filling operation of evenly distributing the grain across the hold is
initiated. From both an operational and a dust control standpoint, it is
best to keep the spout buried in the grain during this operation; however,
when this is not practical, the hatch must be covered to the extent that
only a 10 ft x 10 ft opening remains; filling then can be continued.
Trimming - The trimming operation is unique to 'tween deckers
and is required when grain cannot fill the voids under the lower decks
312
-------
by general filling. During this period, the grain must be "thrown" under
this deck, a distance that may reach 32 ft. Either a trimming machine
("slinger") or a simple deflector must be used for this operation. If a
simple deflector is used, the hatch can be covered and most of. the dust
eliminated. To date, control of 50% of the dust emissions generated by the
trimming machine has been accomplished by adding a flexible hose to the air
duct, inserting this in the funnel of the trimming machine and covering the
unit to channel this airflow.
Topping - The filling of the top 4 ft of the hold can produce
more dust than any other general filling operation. This is caused when
the grain dust which has been generated is captured by the wind before
it can settle into the hold. To reduce the dust, it is essential that
the spout be buried in the grain at all times. No other feasible method
is available to reduce the dust. The topping operation is not hampered
by this practice; it is much faster and cleaner than other methods which
held the spout above the grain.
Tankers or bulk carrier wing tanks - Filling of tanks is broken down
into two operations: general filling through the "hard hat" and final
filling of the void in the tank through the Butterworths.
Hard hat filling - In most cases, the "hard hat" can be filled
by inserting the main spout directly in the hold and having the exhaust
air go up through the spout. By closing the Butterworths, all the air is
exhausted through the "hard hat" and up the spout vacuum system. No other
covering is normally necessary; however, if the spout does not fit directly
into the "hard hat" covering may be necessary to better direct the grain
flow.
Butterworth filling - To fill Butterworths, the spout must be re-
duced and attached to an airtight 12-in. flexible steel tube; the end is
inserted into the "Butterworth" and filled at a rate not exceeding 600 ton/hr.
The damper on the supplementary exhaust duct closes the opening to the load-
ing spout. A 12-in. flexible plastic hose is placed over the duct end and
inserted in the farthest Butterworth from the loading as practical. This
allows for maximum settling of the dust; there are virtually no emissions
from this loading mode.
Grain Transfer Points - Most emissions from transfer points can be controlled
by proper hooding that is exhausted to a collector. The hooding designs may
vary, but they usually are constructed so as to cover the transfer points and
minimize the area open to the surroundings. The quantity of air exhausted
from each hood is generally based on open area exposed to the surroundings.
If several hoods are used along one belt, they are normally connected to a
common exhaust duct and each connection includes a slide gate to provide for
proper adjustment of airflow.
313
-------
One of the more difficult-to-control transfer points is the "tripper"
on each gallery belt. This tripper is moved along the belt to discharge
the grain into the proper bin, and this is a transfer operation that is
difficult to control. As the grain is diverted from the gallery belt by
the tripper it generates dust that is released into the gallery area and
escapes through windows and other openings. Proper hooding on the tripper
will allow capture of most of the dust emission but the required mobility
of the tripper requires special arrangements to exhaust air from the tripper
to a collection device. Some terminal elevators have installed an exhaust
duct alongside the gallery belt, with connections in the duct at each loca-
tion where the tripper may be positioned. This requires that the tripper
be manually connected to the exhaust duct each time the tripper is moved.
Other elevators have eliminated this problem by installing an exhaust duct
with a rubber zipper along the length of the duct so that the tripper is
always connected to the exhaust duct regardless of its position.
One of the latest developments in control of emissions from transfer
points is the use of completely enclosed conveyors and this may be coupled
with pressurization of the surroundings to eliminate any posibility of dust
escaping into the room. Such units are especially applicable to conveyors
in the basement area of the elevators, but they might also be adapted for
use in the gallery.
Grain Dryers
Screen systems used to control emissions from grain dryers were de-
scribed on pages 287 to 289. Emission test results on a limited number of
installations are reported on pages 131 to 142.
Feed Mills
Reference 15 presents an extensive discussion of dust control systems
for feed mills. Only the dust control systems for grinding and pelletizing
operations will be briefly discussed.
Grinding Operations - Cyclones used on pneumatic conveying operations
associated with grinding operations can be significant sources of emission.
Many feed mills are reluctant to use fabric filters on pneumatic conveyor
systems because of the possibility of cross-contamination of ingredients.
However, fabric filters can be used to control the exhaust stream from the
product recovery cyclone on the conveying system if the cyclone is not
operating with high enough efficiency. Use of full circle hammermills,
which may or may not require airflow for proper grinding depending upon the
desired product, can reduce the emission potential.
314
-------
Locating the grinders above the storage bin so gravity feed rather
than pneumatic conveying can be used is advocated by some; however, it
can pose a serious fire hazard since fire could spread to the bins and
not be confined to the grinder as it is in conventional systems.
To reduce emissions when grinding potentially dusty materials (e.g.,
dehydrated alfalfa), some plants are spraying small amounts of water into
the grinding system.
Pelletizing Operations - Because of the high moisture content of the effluent
stream, only cyclones have operated reliably to control emissions from pellet
coolers. Efficiencies typically range between 90 and 97%. The units can
normally operate with little or no visible emissions unless a powder such as
cottonseed meal is being used to prevent caking of pellets. In such cases,
dust emissions can be profuse, up to 507o equivalent opacity. A fabric filter
installation has been tried but the unit has not operated satisfactorily be-
cause the high moisture content of the effluent stream produces fabric
blinding.
Wet Corn Milling
Steeping - Sulfur dioxide emissions from steeping operations are generally
not controlled. The use of packed scrubbers has been proposed and should
work satisfactorily if the pH of the scrubbing liquor is controlled^
Drying Operation - Dryers are almost universally controlled by cyclones which
in some instances are the high pressure drop recirculating type cyclone. For
germ and meal drying, these devices can operate with high efficiency and
minimal visible emissions.
Controlling emissions from feed dryers can pose a substantial problem
since the emissions consist of solid particulates and condensable gases.
Extremely high drying temperatures, coupled with variations in the charac-
teristics of the materials to be dried, can sometimes create an aerosol type
emission which may be visible as a blue haze. Lower drying temperatures
will often minimize this condition. However, lower drying temperatures re-
quire more air, more equipment and more fuel resulting in more dilution.
The volatile organics emitted from the drier are in the gas phase and
condense when emitted to the atmosphere. Various types of scrubbers have
been tried on pilot scale with only limited success. Afterburners could
be used to control both the condensable particulate and odors, but the
large gas volumes would make their use very costly.,
315
-------
Soybean Processing
Processing Operations - The operations in the processing section of a soybean
plant are cracking mills, dehulling, conditioning, flaking, drying, cooling,
grinding and toasting. Of these, the product recovery systems for the meal
drying, cooling, and grinding, and the hull grinding operations are the major
sources of emissions.
Cracking mills are not a major emission source. Medium to high energy
cyclones operate with 95 to 99% control efficiency. Fabric filters operat-
ing at 99+% collection efficiency are often used, usually preceded by a low
to medium energy cyclone.
Dehulling, conditioning, flaking, and toasting operations are other
emission sources. Control efficiencies of high energy cyclones of 87 to 99%
have been determined from stack tests on these operations. Fabric filters
are also used on sources where the moisture content of the exhaust stream
permits their use.
Product recovery systems for meal dryers (usually medium to high energy
cyclones) are most often controlled by high energy cyclones or wet scrubbers.
Control systems must be insulated because of the high moisture content of
the effluent gas stream, i.e., to prevent condensation.
Meal grinding and hull grinding operations produce very fine (1 P-m)
particulate emissions which are often controlled by high energy inertial
devices or by use of a fabric filter. Product value precludes the use of
a wet scrubber system on these operations.
Grain Milling
With the exception of intermediate product drying in dry corn milling
plants, control of dust emission from milling operations can best be accom-
plished with fabric filter systems. Cyclones are used on the dryers in
dry corn mills as the moisture content of the exhaust stream precludes the
use of fabric filters. In the milling section of a grain milling plant, the
product recovery systems associated with the various pieces of milling equip-
ment are the potential sources of emission. If fabric filters are used for
the product recovery, secondary dust control systems would not be required.
316
-------
CONTROL SYSTEM COSTS
Control Device Costs
Figures 45 through 51 present capital cost as a function of capacity
for various types of control devices used on the grain processing emission
sources.* These figures represent the cost of the control and those appur-
tenances usually considered a part of the control device (e.g., rotary valves,
bags) but not such items as ductwork, fans, starters, motors whose costs vary
considerably from one installation to another; nor do they include the in-
stallation costs.—'
The total installed cost for a given installation is highly variable,
depending upon such factors as:
Type of installation, new or existing plant;
Type of labor used, plant or contract labor;
Type of process controlled; amount of ductwork required; and
geographical location.
Existing plants may have much of the hooding systems and ductwork already
installed and require only the installation of a new control device and fan.
Thus the total installed cost for upgrading the controls on such a facility
might be less than for a new plant. On the other hand, such factors as space
limitations, the necessity of working around existing procesis equipment, and
providing additional structural support for the collectors, increase the
total installed cost. In general, the costs to a new plant, where the con-
trol system is an integral part of the plant design,are less expensive than
the control cost for older plants. Table 159 lists the approximate cost range
for controlling specific types of emission sources. These figures represent
only the normal cost range, which would be applicable to perhaps 907o of the
various source types. Control by cyclones is less expensive than control by
fabric filters, and the lower cost figures in Table 159 are for cyclone
systems. Because of the large variability in costs, the cost to control an
individual facility must be determined by careful evaluation of the particular
requirements of that facility.
* October 1972 dollars.
317
-------
1.00
U
0.50
0.20-
0.10
1000
O 2.5 in. H2O Pressure Drop
D 6.0 in. H2O Pressure Drop
I I
2000 5000 10,000 20,000
AIR HANDLING CAPACITY, CFM
50,000
Figure 45. Cyclone collector - equipment cost includes basic unit,
dust hopper, scroll outlet, weather cap and support stand.—
318
-------
3.00
2.00
1.00
u_
U
0.50 -
0.20
0.10
1000
I I I I I I
2000 5000 10,000 20,000
AIR HANDLING CAPACITY, CFM
50,000
Figure 46. Inertial cyclonic recycle type-equipment cost includes:
basic collector; rotary valve and motor; secondary fan and motor
177
319
-------
3.00
2.00
1.00
0.50
0.20
0.10 i
1000
J I L
2000 5000 10,000 20,000
AIR HANDLING CAPACITY, CFM
50,000
Figure 47. Fabric filter - equipment cost includes basic unit, complete
with air pump and rotary valves, motor, starter .iZ/
320
-------
3.00
2.00
1.00
u_
U
0.50
0.20
0.10
1000
J I
2000 5000 10,000 20,000
AIR HANDLING CAPACITY, CFM
50,000
Figure 48« Wet scrubber for gaseous pollutant control - equipment
cost includes pump, pump motor, and recycle piping.—'
321
-------
2.00
1.00
•5 0.50
0.20
0.10
10,000
J I I I I
20,000 50,000
AIR HANDLING CAPACITY, CFM
100,000
Figure 49. Wet scrubber for gaseous and particulate control-equipment
costs include: basic scrubber stand; piping; recirculation
pump; control panel; fuse connect; and instrumentation.il/
322
-------
o
o
o
o
00
o
o
o
0
o
8
0
CN
2
u
>:
1—
u
Q_
^<
u
o
-7
*
Hi
Q
•7.
I
—
"^t
1
i-4
a.
j»i
a)
f
,0
3
}_i
CJ
CO
co
CD
•a
3
1
CJ
d
•H
CO
O
CJ
4J
d
0)
I
•i-4
3
tr
01
i
fi
^ o
d
CJ
CO
lo
r«4
r-l
0)
a
e
M
•
0
0)
t-i
3
60
•H
S-l
^1
3
CO
S-i
0)
4J
CO
fe
Jj
o
PLI
a
3
ex
d
to
•a
CO
0)
3
O
d
4-1
O
co^i|
S B
O 0)
j-i
CO
^ CO
o
4J r-l
o to
e co
0
« a.
d co
CO -r-l
4-4 13
o
vQ
o
C)
o
CO
o
CN
o
o
o
0 0
323
-------
30.00
20.00
10.00
u_
U
5.00
1.00
TOO
i 1 . i i i I i
500 1000 2000
AIR HANDLING CAPACITY, CFM
5000
177
Figure 51. Afterburner-equipment cost.—'
324
-------
Table 159. APPROXIMATE RANGE OF CONTROL COST
(Total Installed Cost)
Operation
I. Grain Handling
Receiving
Truck dump
Boxcar receiving
Hopper car receiving
Barge receiving
Drying
Cleaning
Transfer operations
Scale and garner
Transfer
Loadout
(truck, boxcar,
hopper car, ship,
barge)
Typical Range
of cfm
10,000 - 20,000
10,000 - 20,000
10,000 - 20,000
10,000 - 20,000
30-100 cfm/bu/hr
, 1,000 - 10,000
Depends on plant
configuration
Installed Cost
$/cfm
1.75
1.75
1.75
1.75
4.00
4.00
4.00
4.00
0.25 - 0.75
5,000 - 15,000 (each) 2.00 - 3.00
1.50 - 3.00
5,000 - 20,000 (each) 2.00 - 4.50
II. Feed Mills
Receiving, transfer
and loadout
Grinding
Bin vents
Pelletizer and pellet
cooler
(see grain handling operations above)
4,000 - 8,000 1,50 - 3.00
200 cfm/bin 3.00 - 8.00
20,000 - 30,000 (each) 1.20 - 3.00
325
-------
Table 159. (Continued)
Operation
III. Flour Milling
Receiving and
transfer
Cleaning and
tempering operations
Milling
(break rolls,
sifter, purifiers,
haramermills)
Pneumatic loadout
Typical Range Installed Cost
of cfm $/cfm
(see grain handling above)
25,000 - 35,000 (total) 1.50 - 2.50
35,000 - 45,000 (total) 1.50 - 2.50
5,000 - 10,000
2.00 - 5.00
IV. Durum Milling
Receiving and
transfer
Cleaning house
(separator,
aspirator,
disc separator,
scourer,
tempering bins)
Milling
(break rolls,
sifters, purifiers,
hammermills)
Pneumatic loadout
(see grain handling above)
50,000 - 65,000 (total) 1.50 - 2.50
80,000 - 110,000 (total) 1.50 - 2.50
(see flour milling)
V. Dry Corn Milling
Receiving and
transfer
(see grain handling operation)
326
-------
Table 159. (Continued)
Operation
V. Dry Corn Milling (Continued)
Cleaning house
(screens,
millerator, scourer,
stoners)
Tempering and milling
(break rolls, sifters,
purifiers, expeller
cake hammermills)
Drying, sifting,
and cooling
Typical Range
of cfm
Installed Cost
$/cfm
15,000 - 25,000 (total) 1.50 - 2.50
25,000 - 35,000 (total) 1.50 - 3.00
10,000 - 30,000 (total) 1.50 - 3.00
VI. Wet Corn Milling
Receiving and transfer
Steeping and wet
milling
Germ and gluten
drying and cooling;
feed cooling
Feed drying
Pellet mills and
pellet cooling
Feed house
Dry starch grinding
Starch drying
Flash
Rotary
Corn syrup solids
drying
(see grain handling above)
8,000 - 12,000
not normally
controlled
5,000 - 20, 000 (each) 2.00 - 3.00
30,000 -
8,000 -
8,000 -
2,000 -
35,000 -
4,000 -
45,000 (each)
12,000
12,000
5,000
40,000
6,000
3.50
2.00
2.00
4.00
1.50
3.00
-5.00
- 3.00
- 5.00
- 5.00
- 2.00
- 4.00
18,000 - 25,000
2.50 - 3.50
327
-------
Table 159. (Concluded)
Operation
VII. Soybean Processing
Receiving and
transfer
Cracking mills,
flaking,
conditioning,
dehulling and
screening
Meal drying
Meal cooling
Hull toaster
and grinder
Installed Cost
($/cfm)
Typical Range
of cfm
(see grain handling above)
5,000 - 15,000 (each) 2.50 - 4.50
8,000 - 12,000 2,00 - 6.00
10,000 - 20,000 2,00 - 3.00
5,000 - 20,000 (each) 2.00 - 3.50
VIII. Rice Milling
Receiving and
transfer
Cleaning house
(scalper, screen,
disc separator,
scourer)
Grinding, hulling,
shelling, paddy
separation
(see grain handling above)
25,000 - 35,000 (total) 1,25 - 2.00
8,000 - 10,000 (each) 2.00 - 3.50
328
-------
Recovered Dust Value
In some cases, the recovered dust from the control devices may be sold
for use as animal feed. Because of the local nature of such markets, the
prices received for the recovered dust are highly variable. In some cases
there are simply no developed markets, whereas in others, plants can sell
the material. In most cases, the disposal of this material does not present
a solid waste problem since local sources can usually be found which will
take the material.
Insurance Credits for Installation of Control Devices
Insurance rates are affected by the use of air pollution control
systems. However, only those aspects of the control system which have a
bearing on the explosion or fire potential of the facility are considered.
Thus, for control devices venting to the atmosphere, there is no additional
credit for use of a high efficiency over a low efficiency collector. Con-
trol of outside sources of emission (e.g., truck dumps) does not influence
the insurance rate.
Fabric filters located inside the building are considered an increased
fire hazard. If a fire or explosion should occur elsewhere in the elevator
or mill, the fabric filter is susceptible to ignition. Fabric filters lo-
cated outside the building are not considered an increased fire hazard.
To minimize this fire and explosion hazard, some plants have installed CC>2
purge systems in the baghouse. The increased premium for baghouses inside
the building may amount to several cents per $100 of coverage. A typical
mill with six fabric filters installed inside the building paid an added
charge of 11-1/2 cents per $100 of coverage. However, this same mill re-
ceived a credit of 19 cents per $100 of coverage for the pneumatic convey-
ing system.
An elevator with good dust pickup or hooding systems may receive a
credit of approximately 3 to 5 cents per $100 of coverage.
329
-------
CHAPTER 4
REFERENCES
1. Kice, Jack. Private Communication. Kice Metals Company, Wichita,
Kansas, December 1972.
2. Industrial Ventilation. A Manual of Recommended Practice, American
Conference of Governmental Industrial Hygienists, Edwards Brothers
Inc., Ann Arbor, Michigan. Eleventh Edition, pp. 5-108, 1970.
3. "Control Techniques for Particulate Air Pollutants," AP-51, PB 190253,
U.S. Department of Health, Education and Welfare, January 1969,
National Technical Information Service, Department of Commerce,
Springfield, Virginia.
4. Cyclone Dust Collectors. American Petroleum Institute, New York,
New York, 1955.
5. Op cit., supra note 3.
6. MacKenzie, J. M. "The Determination of Dust Concentrations in Flour
Mill Exhaust Systems," presented at ASME Meeting, Minneapolis,
September 27, 1951.
7. Converse, J. "Clean Air from the Seed and Grain Handling Industries,"
speech presented before the ASAE Meeting, Portland, Oregon, October 7, 1971.
8. Aerodyne Type S Collector. Equipment brochure. Aerodyne Development
Corporation. Cleveland, Ohio.
9. Handbook of Fabric Filter Technology, PB 200-648, Environmental Pro-
tection Agency, National Technical Information Service, Department
of Commerce, Springfield, Virginia.
10. Goldfield, J., V. Greco, and K. Gandhi. "Glass Fiber Mats to Reduce
Effluents from Industrial Processes," Journal of the Air Pollution
Control Association,. 20, 466-469, July 1972.
11. "Scrubber Handbook." Wet Scrubber System Study, Volume I, APT, Inc.,
prepared for Environmental Protection Agency, Control Systems
Division, August 1972.
12. Grain Age, December 1971.
330
-------
13. MacKnight, R. J., et al., "Control of Dust Emissions from Ship
Loading," presented at the 63rd Annual Meeting, APCA, St. Louis,
Missouri, June 14-18, 1970.
14. Alsid, H., "Summary Progress Report: Dust Control Pier 86," Environ-
mental Resources Associates, Inc., Seattle, Washington, February
1973.
15. Environmental Controls for Feed Manufacturing and Grain Handling,
American Feed Manufacturers Association, Chicago, Illinois (1971).
16. Air Shock Filter. Type PEF, Equipment Brochure, Buhler Brothers, Ltd.
Uzrwil/Switzerland (1972).
17. Cost data prepared by PEDCo-Environmental for this program.
331
-------
CHAPTER 5
ECONOMIC IMPACT OF DUST CONTROL
INTRODUCTION
This chapter presents an assessment of the economics of dust control
costs upon the grain and feed industry. The initial intent of the analysis
was to determine the economic impact of dust control systems only for new
facilities in accordance with the directives of the Clean Air Act of 1970.
However, since there are few new facilities being constructed when com-
pared to the number of existing facilities in the grain and feed industry,
the long-term economic impact of air pollution control regulations in
this industry will be borne by existing facilities. In order to accurately
reflect the probable economic impact of air pollution control regulations,
the analysis was expanded to include both new and existing facilities.
A series of plant financial models were used to perform the analysis
of the economic impact. Separate models were developed for each type of
plant within the grain and feed industry, and in some cases, for various
sizes of operations within each industry segment. The capacities, handling
rates, operating hours, and other items listed in the individual plant
specifications were selected to represent average or medium-size plants
in most instances. The model plant is representative of the particular
industry; however, it is not meant to represent the total industry. In
each industry segment there are significant variations in the size, con-
figuration and operating characteristics of different facilities. These
variations will affect the economic impact which air pollution control
requirements will have on specific facilities.
The limited scope of the present study barred a detailed parametric
study of the economic impact as a function of plant size and configura-
tion, and the model plants used in the analysis only present a simplified
flow diagram for each type of facility. As a consequence, there are some
weaknesses and shortcomings in the model plant concept. For example, it
was not possible to incorporate variable factors such as:
332
-------
(a) Product mix between plants and within a plant;
(b) Alternative processing techniques and equipment selection;
(c) Plant site and layout; and
(d) Plant size.
Because of the limitations imposed by the model plant approach, the re-
sults of the economic impact analysis should be viewed as indicative of
the probable economic impact and not the absolute impact.
In addition, the economic analysis for each model plant had to be
made using prices, interest rates and operating expenses for a specific
time period. In all cases, the analysis was made using the most current
figures available; however, these figures will change over time. The
prices and general economic conditions in the grain and feed industry
have been changing rapidly since the middle of 1972. These changes in
raw material, operating and construction costs can alter the economic
impact of pollution control equipment on the various industry segments.
The economic impact analysis was performed for two distinct cases
of dust control in each industry category:
Case 1 - Installation of the best demonstrated control system
currently available for each specific source.
Case 2 - Installation of control systems that generally reflect
current industry practices.
The dust control equipment selected for individual emission sources
in Case 1 represents MRI's judgment of the "best" demonstrated control
system currently available for the specific source. Selections of dust
control equipment for Case 2 were based on the understanding obtained
during the course of the program of general industry practice for plants
which have pollution control equipment. In general, fabric filter col-
lectors were selected in Case 1, and cyclone collectors were selected in
Case 2, except for those sources where industry practice (e.g., fabric
filters being used in the mill house of a flour mill) indicated that
fabric filter systems were generally being used to improve recovery of
intermediate or final products.
In selecting the dust control equipment for Cases 1 and 2, considera-
tion was not given to the need to comply with any specific air pollution
333
-------
regulation. Once specific regulations are adopted at either the federal,
state or local level, it may be possible to meet the regulations using
different methods or less efficient equipment than specified for the model
plants.
The basic procedures used to determine the economic impact were the
same for each industry segment. For each analysis, a model plant was de-
veloped with a specified configuration of processing operations. Air
pollution control equipment was selected for each individual emission
source and estimates of the corresponding investment and operating costs
were calculated.
The investment cost required for control equipment on each emission
source represents the total installed cost for a new model plant. These
costs were obtained from detailed engineering cost analysis of the model
plant's operation and the corresponding pollution control equipment.
The total annual operating costs required for the control devices
include electrical charges, maintenance expenses, depreciation expenses
and capital charges. Since these operating costs can vary significantly
over time and from one plant to the next, a number of basic assumptions
were made in calculating the costs for the model plants. The general
procedures used in the analysis for each of the model plants are described
below.
The electrical expense was determined from the hourly operating ex-
pense as quoted by the equipment manufacturers and the hours per year
which the device would be required to operate. The operational hours per
year which are listed for the model plants were estimated from an analysis
of the operational requirements and capacities of each device. Allowances
were made for the fact that some control devices must operate longer than
would be required if each operation were optimally scheduled at plant
equipment capacities. These allowances were made to recognize the operational
realities of the particular facility.
The electrical cost for cyclones in the Case 2 analysis was estimated
at 80% of the electrical cost for a fabric filter. This reduction is
mainly based on the assumption that, not including pressure drop through
ducting, the pressure drop in the filter would be about 4 in. we while
that of the cyclone would be 2-3 in. we. The cyclone systems would also
have somewhat less operating cost than a filter because the cyclone does
not require a cleaning air compressor.
334
-------
The maintenance costs were based on an estimate that 10c/cfm/year
would be required to maintain and repair fabric filter control devices.
This rate includes the labor required for operation and maintenance. The
maintenance cost for cyclone control devices was estimated at approximately
half that required for fabric filters,or 5c/cfm/year. Although this
number is only an estimate relative to that for fabric filters, it is based
on the fact that fabric filters require bag replacement or cleaning plus
maintenance of the cleaning mechanism and possibly a cleaning air com-
pressor. The cyclone on the other hand has few moving parts, perhaps only
a rotary valve (air lock) at the dust outlet, but may require some mainte-
nance for repair of leaks due to erosion, etc.
Depreciation expense was based on a 10-year straight-line deprecia-
tion schedule. A variety of accelerated depreciation methods and optional
depreciation periods could have been used. The period over which the
equipment is depreciated could be based on a (1) 5-year life as allowed
by the Internal Revenue Service for the depreciation of pollution control
equipment, (2) 17-year life which is the IRS guideline for the grain and
feed industry, (3) 60-year life which is the guideline for elevators, or
(4) the actual life of the equipment as estimated by the manufacturers.
Straight-line depreciation over a 10-year period was selected because it
is between the extremes and provides a realistic estimate from which to
determine total annual control costs.
A 57° effective annual interest rate was used to calculate the capital
charges for the control equipment. The 5% rate results from an assump-
tion that the capital required to purchase the control equipment was ob-
tained from an 8%, 10-year note which is repayable in equal yearly in-
stallments. Yearly payments equal to 15% of the original loan are required
to retire the note in 10 years. For the purpose of the model plant analysis,
it was assumed that one-third of the yearly payments, i.e., 5%, is interest
and the remaining portion is principal. Although not technically correct,
this assumption provides an equal annual interest charge for the 10-year
life of the equipment, and provides for a balance between debt and equity
financing. In actual practice, any combination of debt or equity capital
could be used depending upon the individual company involved. Also, the
interest rate which a plant is required to pay for a long-term loan will
vary depending upon a variety of factors, such as the location, size,
stability and financial condition of the company.
To determine the financial impact of air pollution control costs, an
income statement and balance sheet were developed for each of the model
plants. For the two alternate types of control equipment, separate financial
statements were developed for the operation of each model plant, both
335
-------
without and with pollution control equipment. These statements were com-
pared to determine the impact of the control equipment on the financial
condition of new plants.
The financial analysis was extended to include the impact on existing
facilities. For both new and existing facilities, only the primary or
direct economic impact was calculated; that is, the impact from increased
investment and operating costs. Secondary economic impacts were not
quantified.
GRAIN ELEVATORS
Description of Model Plants
Model plants were developed for country, inland terminal, and port
terminal elevators. Figures 52, 53, and 54 present the flow diagrams
and other pertinent specifications for the model plants with "best" con-
trol equipment. The specific features of the model plants represent a
distillation of the knowledge gained from plant trips, discussions with
industry personnel, and data provided in the emission inventory question-
naires. The model plants are not intended to represent any specific
facility, but rather they present a description of the general nature of
operations.
Control Equipment Costs
For each of the model plants, two alternate pollution control sys-
tems are specified. Case 1 represents the "best" demonstrated control
system currently available for each specific air pollution source. The
control devices are not necessarily the optimum equipment configuration
which would be selected from an analysis of the cost-efficiency of the
equipment or from an analysis of the economic cost-benefit to the plant.
Rather the control devices were selected because they offer the highest
level of control which is technically feasible at this time.
In Case 2 the model plants are equipped with cyclones in place of
fabric filters on the grain handling operations. From an operational
reliability standpoint, cyclones may be the only feasible systems for grain
receiving operations at elevators which receive grain with a high moisture
content. Fabric filter systems are reported to blind or plug readily
when high moisture content grains are handled.
336
-------
X
'o
§L
o
U
O
u
_Q
X -Q
o "~
8. '
O -tr
U Q.
S O
00
0)
_Q
II
i+-
-O
_* C
O O
" X
^'3
s. ^ •— n
^i ii 8-
_Q
0)
S.9-
O _Q O
4)
CO
!-<
o
c
o
o
co
0)
O
JJ
0)
^-(
0)
O
o
15
(U
01
T3
O
a
•H
337
-------
D
-Q
o
o
11)
L.
_Q O
0-0 10-
ir 2 «*>
"O
O
O
<
o *.
U D
Q.
0) -JC
O> D>
00
o
O>
'5.
Q.
o m ID
oo •—
D
OQ
0>
-------
o
<
<
o
s
= i
-a 3
V x
x _a m~
' o>
• x j
o •*
a •
o *- ^
° -C 4>
un I— —'
8..
a. £
£3
M
a.
-C
to
| Loadout ]
M
V
S5
cS
e
j-i
^ii
vt
-*
S
i—
Grain Receiving |
1
«
Q- —
ir> in o
?\
0)
U
i E
CD
.—I
O
o
o
CO
CD
43
I
/^s
J-l
!-i
O
O
4J
cfl
•H
a)
T3
O
a)
n
M
•H
S
o
339
-------
For each operation an estimate is given for the investment cost re-
quired for the control devices. Also included are estimates for the total
annual operating costs of the equipment including electrical, maintenance
and depreciation expenses and capital charges. Assumptions regarding
these expenses were discussed in the introduction to this chapter.
A summarization of the total annual operating costs and investment
costs for each alternative is given in Table 160. Annual operating costs
are based upon yearly throughput and installed costs upon plant capacity.
Details of the costs associated with Cases 1 and 2 for the country elevator
are presented in Tables 161 and 162, the inland terminal in Tables 163
and 164, and the port terminal in Tables 165 and 166.
Table 160. SUMMARY OF TOTAL ANNUAL OPERATING COSTS AND INVESTMENT
COSTS FOR CONTROL SYSTEMS ON GRAIN ELEVATORS
Total Annualized
Cost Per Year
Total
Installed Cost
Country elevator
Inland terminal elevator
Port terminal elevator
Case 1
($)
17,642
75,238
96,209
Case 2
($)
14,623
57,238
71,367
Case 1
($)
94,040
354,720
444,830
Case 2
($)
80,262
286,030
355,190
Total Annual Cost
Per Bushel
of Throughput
Total Installed
Costs Per Bushel
of Capacity
Country elevator
Inland terminal elevator
Port terminal elevator
Case 1
(C)
1.76
0.50
0.21
Case 2
(C)
1.46
0.38
0.18
Case 1
(C)
18.8
7.1
8.9
Case 2
(C)
16.1
5.7
7.1
These figures represent the cost of purchasing and installing the
control equipment for a new elevator and the costs associated with
operating them per year. For elevators of similar design, the installed
cost of the equipment will not vary considerably with the storage capacity
or the volume of grain handled. The type and size of the pollution con-
trol equipment are more dependent upon the operations required in receiving,
handling, and shipping grain rather than upon volume.
340
-------
o
o
o
s
-------
C/]
c4
O
H
g
H
HH
U
H
O
U
3
w
z
o
EH
Z
a
PH
MODEL
CS]
vO
,— |
0)
-Q
fr-t
0)
4J
•H
4J
05
b-1
4-J
(0
O
O
Tl
cJ
to
" 'o
8 $
g 3
U jj
! 3
H «
^ -o
< i
i
CM
0)
CO
CCJ
U
'O
CU ^~.
r-t -CO
CO
-U *J
to M
C 0
M 0
T3 ^
OJ >
N --*,
•H
i-H ^
CO
3 4-1
C! M
C O
< U
--W
•°l
oi
MD
CM
CM
in
CM
tr»
00
00
r—< W ^-N
CO OJ )-j
*J 50 >
•^ VJ '-v.
DJ nJ
CO J3 ^
C_3 U
d
0
-H
CO J-i
•H >,
O --^
0) -co-
cu
a)
Q
0)
o
§ £
OJ ---,
4J .
ffl ~~,
>-« ^
«-H D
0) Q
CO
QJ
a
o
i—i
o
X
o
"«l
00
C
>
•H
QJ
O
ti
0
•1-1
•U
CO
f_i
QJ
a
o
0)
M
13
G
R)
4J
3
0
TJ
CO
O
rJ
00
C!
CO
QJ
r- 1
O
M-4
0)
0)
J-.
CO
o
o
o
o
o
CM
tn
00
o
0
a)
rH
A
0)
C3 M
M W
CS C
oo a)
tU (3
l-l -f-<
CD ^3
CJ
c/l
342
-------
o
a
3
&
cn
prf
o
H
<3
>
W
r-3
hJ
<
[z;
M
§
W
H
13
g
CM
H
13
P,
>H
Q
0
S
CO
>-o
(—1
QJ
X>
CD
H
QJ
4J
CO
.§
jj
[ii
4J
CO
O
u
T3
d
cfl
r— 1
O
Jj
c
s s
c e
o S
u S
p..
4J
« rH
% OJ
PQ ^
. 0
1 s
t-H
Q)
w
rd
U
Q) x-,
i | ^_
Cfl
ui tr
d o
M U
T3 M
CD >-
•H y>
i — 1 ^-^
CO
C cr
C 0
,
O --v
Q)
QJ •"-*.
4-1
Cfl
s
cfl
O x— \
•i-i i-i
i-i >
4J --^.
cj t/>
QJ W
W
O X-N
•U >
CO \
S-l r-l
Q) J2
O
g
r-l X-N
M-l
h o
•H "^s
QJ Q>
4J C>
QJ >
T-i QJ
QJ Q
cn
C
o
•r-i
±j
nj
j_i
CD
D.
o
O
^D
in
CO
\o
CN
i— 1
t^
CM
GO
r- <
3
m
0
01
CM
I—I
0
m
0
o
o
-H"
O
CM
CM
^
QJ
••-I
t-i
DO
-T-t
•I-l
QJ
a
QJ
)-l
CJ
3
to
H
O
o
o
o
cO
o
CM
m
^Q
0
0
r— 1
O
o
o
CO
o
o
T— 1
0
CM
CO
o
o
m
o
o
o
m
to
QJ
3
pj
bO
d
•H
•S
Q)
0
QJ
(-1
CO
fj
CO
0
S-i
I—I
•I-l
to
O
f^
00
T-H
r- 1
o^
01
CO
CTi
CM
£
CO
o
o
0
r-l
0
o
rH
o
o
CM
O
o
o
o
M
QJ
••-I
PH
00
d
•r-l
to
0
r-l
M
nj
O
O
PQ
O
r^
m
CM
T-I
r-l
0
m
CO
CM
r-l
•*
r-.
m
CM
o
o
o
r-l
0
m
!—<
0
o
CO
o
o
o
o
to
QJ
3
PH
60
•r-l
O
r-l
Cfl
CJ
1-1
Q)
a
a
s
0
o
^
,J-
CM
m
CM
0
m
m
CO
CM
T-I
O
r-.
CM
O
O
0
I— 1
O
CM
CO
0
o
m
o
o
0
o
to
QJ
•H
CM
d
•r-l
d
OJ
QJ
i— 1
a
d
•r-l
Cfl
0
00
d
•r-l
tO
QJ
T-I
U
1
M-<
QJ
cn
a;
"O
d
•r-l
Cfl
to
O
o
o
CTi
CO
CM
m
CO
CM
vD
m
d
0)
QJ
to
O
CO
Xi
O
o
o
CM
O O
0 0
m in
co r*.
-sf 0
m in
<£) .
CO
r— 1
O
0
("I
CO
o
u~l
CN
CN
50
CO
•u
H
o ty
o -w
O cfl
^ Cfl
cfl m
*-i o
•u
QJ b
co cn
Q) QJ
" T)
O
« O CO
O O 00
O O QJ
343
-------
in i—i
1°'
o
H
(-1
o o o
. C C <1)
IH M OS
G 43 a
00 60 BJ
TO 3 O
344
-------
H
g
CO
PC-
0
H
3
I-J
§j
H
fS
H
g
o;
o
H
3
PM
i-l
M
1
.
CU
TO
H
d)
4-1
a
•P
cr
4-1
CO
C
T
n
c
01 c
'o £
K ^
£ c
3 jj
CU
4J
CO ,_|
CQ ^
1 v|
rH
a>
CO
TO
Q) /-^
TO
4-J 4-1
CO CO
d o
M U
T3 (-<
>
to ^
•H
rH •-— '
ni
3 4-J
d o
<; c_?
TO cu M
4-J bO >
CU TO
CD ,£ ^
U 0
c;
o
TO )-i
-H >
o --^
CU <0-
r-t -*-*
cu
CU
o
CU
o
C -"
OJ J-I
C! >
cu \
4-1 -CO-
c ^
•I-l
TO
rH
TO
O X— N
•i-l V4
4J ---,
QJ ^--
w
o ---*
•I-l J-I
4-1 >
TO --*.
CU JS
a. "-'
o
PM 6
r-l '->
•H ^-'
a
OJ >
rH CU
CU «
C!
O
•H
TO
a
o
o
^o
u~r
CO
CO
•JD
r^.
oo
n
1— 1
s
«n"
o
CO
CM
F-l
in
o
o
m
0
CM
CN
IH
CU
•H
P*-i
^
GO
C
•H
•H
CU
O
CU
o
H
0
o
O"\
o
0
(•fr
o
CM
O
O
«"
o
o
m
CM
o
r-.
O
r-4
0
o
o
rH
0
O
0
m
CM
CU
•H
pi,
^
c
•H
•H
CU
O
CU
TO
O
13
TO
O
rH
•i-l
Pi
O
CM
rH
CO
00
ro
^Q
CM
*£>
m
rH
m
CM
TH
CO
0
o
m
rH
0
o
CM
o
o
CO
o
o
o
m
rH
CU
•H
PL,
bO
C
•H
CU
o
a>
j-i
0)
bO
TO
CO
o
r-.
00
in
oo
CT\
CO
CM
CO
in
§
o
^
o
in
o
o
o
o
TH
0)
•H
r>.
'oi
SO
fl
•H
TJ
0)
0
rH
TO
O
14
OJ
a
Cu
O
K
O
O
.Q
TJ O
0
C 0
TO CM
O
O
0
in
CO
^~
0
§
*>
0
°.
-
o
0
o
*"*
o
o
o
o"
CM
CU
•H
PL,
GO
CJ
•HI
O
rH
•H
CO
Cl TJ
tfl n]
O
O
m
CO
o
1— J
•o
CU
,c
CO
^
o
3
J-I
4J
14-1
o
4J
CO
o
U
CO
a)
T3
3
rH
0
C
M
TO!
iving stations
QJ
O
0)
n
^
TO
O
rH
•H
TO
}-.
O
s
j-i
o
m
g
m
U
0
m
CM
y-i
o
0
0
CO
CO
\ U|T3|
3
J3
O
0
o
o
o
0
m
t
>!
•P
•H
O
TO
CL
TO
U
0)
bO
OJ
J-i
0
4J
CO
h
r*.
3
Xi
0
O
o
0
0
o
o
>
4-1
•H
O
TO
Cu
TO
U
GO
QJ
h-J
345
-------
OS
s
tn
O
£H
i
hJ
H
hJ
<
1
Pi
M
H
3
O
S
a
w
§
-^
S
CU
rH
H
rn £ o
,-H ^^ m
« *•*
4-14-1 "
do ^
T) JH
O) >-
N ^ _j
•H -CO- *~~^
tH ^ O
to oo
34-1 "
d en **
d o
< u
«-» « 'S _^
(0 Ol M ^"
4-1 60 > £J
•r4 M — , "'
CU CO "
3 6 n
01 d
w o
1 -ST.
w ^ ^
^ CM
CO
O
U
TJ
5
en 'C en
i— ' t-H >• *""'
0 0 *-*. *°
4-1 jj s^-
O O
o o
CU 4J
•JH C
to to
d rH x— ^
S S 17°
0) >1
o •— i
CM
CU
W c!
u 5 ^ o
4-1 >- ^
cO \ ""»
a 6
o
1 ^ s
fe ^ ^
Lj U CM
-H •-' ""^
Q) CU 2
4J O ^
CJ -r-1 °
01 > "~"
T-H OJ °
« P o
C C!
O -H
*4J •<-<
IH °
QJ U
Q
O
U
EH
O
i-H
rC
CM
(j,
r-
rH
^o"
CO
en
**
m
r-
CM
O
CM
rH
m
CO
0
o
o
i-H
o
0
o
>n
CN
C
0
o
o
-~^
d
-•H
•H
CU
O
CU
05
O
T3
O
T-H
•H
CO
K!
0
f-«-
O
CM
en
CM
0
*,
U
00
fl
•H
CU
T-H
d
•H
0)
O
O
C^
CO
CM
m
en
Oi
m"
m
"
o
CO
CM
O
0
in
rH
O
O
rH
O
0
m
o
o
o
o
bO
d
-H
to d
CU CU
i-H (U
U ^
1 U
<4H CO
CU
-ol
01 3
M
O
d o
CO CM
O
o
o
m
r^"
CM
in
o
o
so"
m
r-
cn
"
o
r--
CM
O
o
O
i-H
0
00
CO
o
o
m
rH
O
o
0
o
rH
CN
CM
(0
CU
d
0
o
CU
d
to
ciO
13
d
CU
i-H
CJ
to
o
o
m
CO
01
T-H
o
,-T
CM
CM
"
O
CO
0
o
m
CM
CM
r»-
m
o
o
CM
0
o
0
m
CU
d
o
rH
O
u
00
d
•t-i
d
4-1
C
CO
00
•iH
T-H
d
CO
ol o
0 ON
3 «•
T) ift
1 c^
ol r-
inl ^
VD] en
J ,H-
1 r~
01 r-l
ooj r^
l "
\ *
0| (^
,-t-l _l
VII T-1
H "1
enl in
1 c*l
o| m
o o
ol oo
T-H| c^
ol
x^ -H
IH CU
CO O
cu 'a
cu d
o
1 I
o
JH «— *
U ^
X tfl
0 0
&
0
« MH
O n3
-H O Ol
W O 4J
c3 O ctj
4-1 « i-H
w en 3
en O
. GO )-l
O C *H
m -i-i * u
en > TJ cu
« -H CU IH
0 CU &
I-H o en }H
-------
For example, a truck-receiving station in a country elevator will require
the same basic filter and cubic feet per minute regardless of the number
of trucks which are unloaded during the year. The model country elevator
has the facilities to receive grain by truck and to ship by either truck
or rail—facilities which are available at almost all country elevators.
In each of the new model elevators, the control equipment required
is dependent upon the operational facilities which are available. For
example, less control equipment will be required if the country elevator
does not have a grain dryer. On the other hand, additional control
equipment will be required if the elevator has facilities to receive grain
by rail or to load by barge.
Additional variations in equipment could result from basic design
changes in an elevator's grain-handling operations. For example, a few
elevators have been constructed which utilize an enclosed high-capacity
belt conveyor. At no point in the system is the grain exposed to the
atmosphere, from the time it leaves the unloading pits until it reaches
the storage bins. The pollution control equipment required for such a
system would be less than that specified for the model plant; however,
it is estimated that the increased cost of the enclosed system is as
great as the corresponding decreased cost of control equipment.
Credits for Dust Control
There are a number of control credits or positive impacts which will
result from the installation of pollution control equipment on an elevator.
Possible positive impacts include:
1. Reduction in product shrink,
2. Reduction of maintenance costs through savings on lubricants
and similar materials,
3. Increased life of protective coatings,
4. Labor savings in elevator clean-up,
5. Reduction in fire insurance premiums for stocks, property and
business interruptions, and
6. Tighter insect and rodent control with attendant reduction in
grain losses.
347
-------
The major control credit which will be quantified in the model plant
analysis is the reduction in product shrink. A dollar value will be as-
signed to the dust which is collected from the elevator's operation.
Available emission factor information indicates that if the majority
of emissions were collected from grain-handling operations it would amount
to 1 Ib/ton to 5 Ib/ton of grain received.I/ If the cleaning and drying
operations were included, the total emission rate could amount to over
10 Ib/ton of grain handled. The emission rates will vary depending upon
a number of factors including the type of grain handled, moisture content
and handling processes.
As grain goes through the processing sequence it may be subjected
to several dust control systems and in most cases the collected dust is
returned to the grain stream. Therefore, if the same dust were collected
several times, a savings to the elevator based on value of dust collected
by each system would be high.
Dust collected in a pollution control system can be (1) returned to
the grain stream or, (2) separated from the grain and sold as a by-product.
Some of the existing control systems on elevators automatically return
the dust to the grain stream; however, in most cases a new elevator may
choose either option. The exception results from the federal and state
regulations for official weights and measures which specify that once the
grain has been weighted for loading, nothing can be extracted. These
regulations require terminal elevators to return dust collected in the
load-out operation to the grain stream.
The value of dust which is collected and returned to the grain stream
is dependent upon the price discounts for "dockage" and "foreign mate-
rial" in various grains. The Official Grain Standards of the United
States±Z' specifies the dockage and foreign material standards for each
type of grain. For wheat and grain sorghum, the grain dust is included
as "dockage." For corn and soybeans, dust is included in "foreign mate-
rial."
The discount for dockage or foreign material varies for each type of
grain. For wheat, dockage is expressed in half percent increments, e.g.,
dockage ranging from 0.5 to 0.9% is expressed as 0.5%, from 1.0 to 1.4%
as 1.0%, etc. Up to 0.5% dockage is allowed without a discount in price.
If dockage is 0.5% or greater, then the weight of the grain is discounted
or docked by the same percentage. The amount of dockage will vary by
geographic area, year and other variables; however, the majority (over
75%) of wheat shipments will have at least 0.5% dockage.
348
-------
For grain sorghum, dockage is expressed in 1.0% increments and a
maximum of 1.0% is allowed without penalty. If dockage is over 1.0%,
then the weight of the grain is discounted or docked by the dockage per-
centage.
For corn the dust is included with "broken corn and foreign mate-
rial," which is measured in 1.0% increments. For U.S. No. 2 grade corn,
a maximum of 3.07o broken corn and foreign material is allowed. For each
1.0% over the 3.0% limit, corn is discounted by 0.5 to 2.5c/bu. The per-
centage of broken corn and foreign material can vary significantly. Corn
received at the Kansas City Board of Trade in 1973 was usually in the
2.5 to 3.07, range; however, corn which has been dried may go to up to 8.0%,
For soybeans, foreign material is measured on 0.17, increments. A
maximum of 1.0% is allowed for U.S. No. 1 grade soybean and 2.0%, for No.
2 grade. For soybeans, the foreign material percentage over 1.0% is
deducted from the shipment weight. Almost all of soybean shipments
received some discount for foreign material.
For each of the major grains, the addition of dust to the grain
stream will usually reduce the value of the grain in direct proportion
to the weight of dust. This means that the dust has no value if added
to the grain.
There are some exceptions to this generalization. For example, an
elevator could add wheat dust back to the grain stream and increase the
dockage from 0.4% to 0.6%. In this case, the addition of 0.2% dust de-
creases the value of the wheat by 0.5%, i.e., the dust has a negative
value. On the other hand, the addition of wheat dust to the grain could
change the dockage from 0.2 to 0.4%. In this case, the 0.4% dockage is
still under the limit for wheat and the dust will be equal to the value
of the grain.
A few of the modern terminal elevators may be able to accurately con-
trol the addition of wheat and corn dust to the grain streams in order to
take advantage of the maximum allowable dockage or foreign materials
limits. However, in most cases the dust will have a greater value if
sold separately as a feed ingredient.
For the purpose of this study it was assumed that the dust collected
from all operations could be sold for §10/ton. Depending upon the market
conditions, the value of elevator dust can vary from $0 to $30/ton. Ac-
cording to industry sources the value over the past 2 years has averaged
around $5/ton. However, if a reliable supply were established, more feed
349
-------
companies could develop procedures to utilize the dust and as a result,
the average price would probably increase. Even with a more established
market, the small country elevator could still have problems in estab-
lishing a market for their dust.
For the purposes of the impact analysis, five optional emission
factors were evaluated--from 1 Ib/ton to 5 Ib/ton of grain handled. The
resulting control credits for each model elevator are shown in Table 167.
The credit at an emission rate of 5 Ib/ton would amount to 4.3% of the
annual operating costs of best controls for the model country elevator,
15.07=, for the model inland terminal and 31.2% for the model port terminal.
In addition to the value of dust collected, the other positive im-
pacts undoubtedly produce some tangible economic benefits to the model
plants. However, it is difficult to quantify these benefits and their
total impact, even if quantified, would probably not significantly re-
duce the impact of the pollution control system on the model plants.
Financial Statements
To determine the financial impact of air pollution control costs upon
elevators, an income statement and balance sheet were developed for each
of the model elevators. Separate financial statements were developed for
the operation of each model plant both without and with pollution control
equipment. These statements were compared to determine the impact of the
alternate types of control equipment on the financial condition of new
plants.
Income statements for the country elevator, inland terminal, and port
terminal were developed using a number of published sources and numerous
contacts with knowledgeable individuals in industry and government. The
principal source of information, particularly for expenses, was the
Economic Research Service publication, Cost of Storing and Handling Grain
in Commercial Elevators. 1970-71 and Projecting for 1972-73.17Other
references used in the development of the financial statements are listed
in the bibliography--Refs. 3-13.
The operational specifications for the model plants are listed in
Table 168. These specifications were selected to represent an "average"
elevator's operation and do not apply to any specific establishment. If
available, information was selected which represented the 1972-1973 crop
year.
350
-------
Table 167. POTENTIAL CONTROL CREDITS FOR
DUST CONTROL TO MODEL ELEVATORS
Assumed Recovery
of Grain Dust
(Ib/ton grain handled)
Country Elevator:
1
2
3
4
5
Inland Terminal
Elevator :
1
2
3
4
5
Port Terminal
Elevator:
1
2
3
4
5
Grain Total Dust
Handled Recovered
Iton/yr) (tons)
30,000 15
30
45
60
75
450,000 225
450
675
900
1,125
1,200,000 600
1,200
1,800
2,400
3,000
Value of
Dust*/
Recovered
($)
150
300
450
600
750
2,250
4,500
6,750
9,000
11,250
6,000
12,000
18,000
24,000
30,000
Value Recovered as
Percent of
Control
Case I(7o)
0.9
1.7
2.6
3.4
4.3
3.0
6.0
9.0
12.0
15.0
6.2
12.5
18.7
24.9
31.2
Annual
Cost
Case II(%)
1.0
2.1
3.1
4.1
5.1
3.9
7.9
11.8
15.7
19.7
8.4
16.8
25.2
33.6
42.0
a/ Assumed that recovered material could be sold at $10/ton.
351
-------
CO
o
H
o
w
EL!
^
i— i
"•^
o
C/3
£_i
^
3
P-I
.j
H
n
0
Cd
o
rT .
W
y-r
O
M
H
1 — i
tu
l— l
W
PH
^
O
M
H
CM
rTi
PH
o
,
OO
rH
CU
I— 1
x>
CO
H
i— l
CO
C
•H
CO
£-4
[ f
rl
0
PH
3
Xi
O O
0 •
o oo
n
o
0
o
n
in
1 — 1
CO
a
•H
g
CU
T3
C
CO
C
M
3
X>
o o
o
O CO
«
O
o
0
in
VH
0
4-1
CO
CU
rH
W
»>.
!H
4J
C!
3
O
CJ
3
Xi
O 0
o •
O CN
n
o
o
in
4-1
•iH
O CU
CO 4J
CX CO
CO Pi
o
rl
(U CU
60 >
CO 0
O rl
4-1 3
en H
3 3
XI XI
0 0
0 0
o o
n *
0 0
0 0
0 0
i— 1 rH
3 3
X! XI
o o
0 0
0 0
0 O
o o
m o
O
3 3
XI XI
O 0
0 0
0 0
f~. f\
o o
0 0
-3° co
-o
CO
rH
TJ
a
CO 4-1
33 cfl C
CU j-i
c x: o
•H 13 U
CO
rl
3
XI
& — 6*^ &*-•
o m in o
O rH t^ rH
o
*,
o
o
o
•l
00
3
XI
§*> 6s*-
o bo
O
CO X>
rjj
CO 60
XI -H O rH CU
>, > 3 i-l 4J
O -rl i-l CO CO
cn cu H cd rs
o
CU
3
XI
^D ^3
O 0
rH O
f,
o
o
0
rH
3
•°
in in o
00 rH 0
o
n
in
CN
rH
-. 3
X> rH
o
60 J£ rl >
C O rH CU
•in 3 -H 4J 60
CX rl CO CO (3
&. H Pi !S 1-1
x: tH
U1 O
&""*
00
•
oo
\Q
T3 O
CU C
•H CO
rl CX
P 3
O
3 0
W O
x: cu
0 60
CO 50
W M
^— ' CU
p>
3
XI
o
m
m
X)
o
-d-
3
Xi
0
1^
•o
C
CO
60
C
K*> ! 1
4J T3
•H C
a co
03 P3 "^,
CO C 60
o o c
•H
CO C to
60 i-l -H
CO 60 T3
IH rl C
O co CO
4-1 g x:
co o
CO rl
^S CO CO
N~/ O ^
J_l
o
^
>. 3 3
Xi XI
3 — - --•
XI O- O
•>-. m o
o •
VD CO
^ —
^
rH
M
>. 3 3
XI XI
XI O- O
-^ in CM
o
\Q t— (
* in rH
• -C/}-
^H,-
rH
t-l|
60
n ~*~-
•H T3 1
t^ 4-1
rl tO
-^, Q 0
X> O
to C
CO O C!
4J O
CO 13 .H
rl -H 4-1
60 O
CU rl 3
60 CO M
CO g W
O 4-1 0
4-> CU O
CO Z O
3
XI
ON
00
i-H
-
3
XI
CN
cr.
•
, — i
3
^
irt
|*N.
•
Y— )
•^
TD
CU
4J
X!
60
.rl
CU
•
CO
4-1
CJ
CO
4J
a
o
o
r^l
rl •
4-1 rH
co r-.
3 cj"»
T3 rH
C
•H -
rH
p>-,
XJ >!
rH
T> 3
cu >-i
T3
•H MH
> 0
0
M CO
CX CO
to to
13 cu
•iH 4-1
60 CO
rl Pi
CO
p* Hi
Q
CO
to cu
O rH
rl 3
60 T3
CU
CU X!
60 O
CO C/l
CU O
> 0
->
CU rl
CO 4J
CU CO •
PC! 3 rl
•U CO
60 13 CU
C" 1-1 rS
•H
4J g CX
CU O O
.it! rl M
H MH o
CO
S T3 CN
co r^
- C l
CU vH rH
o co r^
•H 4J a\
> XI rH
M O
CU rl
CO CO O
4J MH
CU CO
5> O to
•H O CU
4-1 O
CO C -.H
rl O rl
CU -p4 CL
fX -I-1
O 0 CU
0 3 60
O rl CO
4J M
rl W CO
CU C >
6 0 CO
M 0
co a
fin CU O
60
** CO rO
•< SH CU
Q CU CO
CO > co
-^^ --^^ --^^
o| -a| cu|
352
-------
The resulting income statements for the three model plants are
presented in Tables 169, 170 and 171. Income taxes were not calculated
because many of the elevators are owned by farmer cooperatives which do
not pay corporate income taxes. The net margins (net income before taxes
per bushel handled) shown in the income statements are for new elevators.
Because of greater depreciation expenses, the profitability of a new
elevator, particularly a country elevator, may not be as great as that
for the average existing elevator.
In general, the operations, expenses and profits of elevators have
changed significantly during 1972 and 1973. Storage income has decreased
because of a reduction in the quantity of grain stored by the USDA Commodity
Credit Corporation; additional interest expenses have been incurred be-
cause of increased prices of grain and transportation shortages, and in many
cases the gross margins for handling and merchandising have been increased.
Because of these rapid changes and the general economic instability, the
variations in the financial operations among elevators are significant.
The financial statements for an "average" elevator will not represent the
total industry.
For the new model elevators, the income statements in Tables 169,
170, and 171 are summarized as follows:
Pollution Control Equipment
Country elevators:
Case 1 - Best controls
Case 2 - Alternate controls
Inland terminals:
Case 1 - Best controls
Case 2 - Alternate controls
Port terminal:
Case 1 - Best controls
Case 2 - Alternate controls
Net Income Per Bushel of Throughput
Without With
Controls Controls Decrease
(0) (C) (C) (%)
2.82
2.82
1.58
1.58
1.24
1.24
05
36
08
20
1.00
1.06
1076
1.46
0.50
0.38
0.24
0.18
62.7
51.8
31.6
24.0
19.4
14.5
353
-------
CC
O
E-»
<
>
H
rJ
W
>-<
Pi
e
^
o
CJ
g
erf
o
cn
s
-S CN
H i-*
E— ( ON
5 rH
CO
S
O
1 — 1
>*
rJ
CT\
\D
O)
,n
ro
H
U)
O
rH
4-J
C
o
CJ
CD
-U
nj
C
V-i
CU
•U
r-H
<
w
0 ^-v
S-J CO
4J ^H
C CO
0 --H
U i — t
0
•H
s
CO
4J
M ^->
0 LTj
0 £
rH *
O r^H
^ 0
d 5
0
o
CO
o
rJ
4J
C
0
U
-U
cn
0)
ffl
1
QJ
tn
m
u
cn
O '-v
^ CO
-U rH
C CO
o
£ 8
•iH
&
W
tn x-x
O cn
"^
U 0
U O
c *^
o
o
yi
r-l
O
VH
4-J x-s,
C co
0 M
r-H
4J r-H
3 O
-d ^^
4-)
•H
rS
CO O i-H O
O o
O O.
CO
01
CO
d
01
ex
01
i-H
rQ
•r-t
CC
O
3
j_t
CJ
O)
•rH
P
(U
at
•rH
4-J
«
rH
4J
CO
•iH
C
•H
G
*3j
rH
0)
JJ
0
Working (
C!
O
4J
cn
0)
0)
C
M
C
0)
0)
to
•r-t
CO
>
i-H
CO
O
H
0)
«i
C
0)
1
4J
O
H
CO
1
01
M
O
0>
P3
ot
0
Pi
4J
Worth
4-J
a>
OJ
1
o
0
4-1
2
4-J
at
UJ
cn
i-H
cd
4J
o
H
01
o
c
U
0)
1 Hand lee
0)
tn
3
Cfl
0
I-H
4J
354
-------
I
H
Q
5
M
H
21
Pi
O
^
W
W ^
S-. tn
4-J $->
c ro
O r-l
o
4-1 ' — '
3
M
cn ^^,
O tn
0 n
O r-H
IM O
J-" Q
O
en
O
4-J
0
u
4-J
CU
m
i
I_)
CU
en
CO
U
to
0 -^
!-j tn
c re
0 '-'
O rH
o
-C O
•H
s
40
o 't/T
U (-1
CO
0 .-i
^ o
^ G
O
O
en
O
4J ^^.
C eo
O *-<
U co
i — i
4-1 -H
3 0
O Q
4-J
•H
o o
000000
o m m o m m
o co o o vi> m
CN ,—i i—i
C
0
o
0
o
m
•— i
CU
6
0
CJ
h- 1
cn
0
O
0)
C
0)
Q,
X
OJ
cn
ti
D
X
"D
C
O
•H
4_J O)
re o
•H C
u re
CO V4
cx to
01 c
O M
cn
QJ
re
H
CU
£X
0
c
o
FQ
•o
C
tn
C
OJ
u
•r-l
Investment
c
o
OJ
CD
4J
C
M
Expenses
^d
QJ
X
•H
i— 1
4-1
o
H
tn
cn
0)
D-
CU
re
t-i
re
o
CO
rJ
a
Q)
Q
ve Overheac
4-1
CO
J-l
LO
C
•H
a
CO
0
00
c
•H
^
^
0
s
c
0
4J
to
0)
CU CL)
O IH
le Expenses
Xi
cfl
•H
>
o
a) a) ca
o o 01
355
-------
r-l
O CO
CJ rJ
CO
rH rH
0 rH
^ O
4J P
c ^
0
CO
8
4-J s-*
C to
CJ CtJ
rH
-U rH
0 Q
u
•H
s
O O O O
O > J-l 4J
•H CJ 0 C
CO 5 U-4 i-(
•r4 tO O
Tt CL p cu
c: 3 K j3
ttf o tit ~---. in
X! O CU O
o o >^ m
OJ 0> 3 M-l J3
S3 00 ,O O
J3 OJ ^N. O
rc3 •• — . }-i O CO O Q)
£ O O "-D BO S
cd CM > * O * O
~ — <3l >!Z O C
O Cd 4J l-l r-l CO
o ffl en o Op
o*» o o
vO O O
O CO CO
CT\ CN vO
co co m
\D
rH
m i i
* 1 1
CO O O
CO O O
O CO CO
CO CM VO
ON co in
to
CO
i i
o o o
moo
m co co
CO CM VO
m co in
\o
CO
CU
w G H
i~<
cfl
CO
-H
0
-H
S
CO
d)
P-
[S
*
,_H
4->
O
rH rH O
Exp
Be
co T3
-------
The income statements do not reflect the control credits which could
be received from the sale of the dust as a by-product. The control credits
shown in Table 167, assuming an emission rate of 5 Ib/ton of grain handled,
would reduce the impact of installing pollution control equipment. The
impact of the control credit upon profitability as measured by net in-
come per bushel handled is summarized as follows:
Pollution Control Equipment With Control Credit
Country elevators:
Case 1 - Best controls
Case 2 - Alternate controls
Net Income Per Bushel of Throughput
With Controls
Without and
Control Control Credit Decrease
(0) _
2.82
2.82
(c)
1.13
1.43
1.69
1.39
59.9
49.3
Inland terminals:
Case 1 - Best controls 1.58
Case 2 - Alternate controls 1.58
1.15
1.27
0.43
0.31
27.2
19.6
Port terminal:
Case 1 - Best controls 1.24
Case 2 - Alternate controls 1.24
1.07
1.14
0.17
0.10
13.7
8.1
For each model plant the balance sheet corresponding to the income
statements are listed in Tables 172, 173 and 174. The current assets are
composed primarily of grain inventories, and the fixed assets are equivalent
to the construction costs of each elevator. The per unit costs were chosen
to represent the average construction cost for each type of elevator. How-
ever, these costs would vary significantly depending upon the type of
structure. For example, a concrete country elevator or inland terminal
would cost around $2.00/bu, or approximately 40% more than the construction
costs which were used.
A summary of the impact of pollution control equipment on new plant
construction costs is as follows:
357
-------
o
H
^J
M
W
^H
PH
^
J"~l
O
u
£g
M
§
pi
o
Pn ^v
CN
H r-~
Cd ON
H r-l
EC >— '
C/3
W
&
<
pq
•
CM
p-*.
r-l
0)
cd
H
CO
i— i
0
l-i
4-1
c
o
o
0)
4J
cd
a
M
0>
4J
CO
r-l
O
4-1 f — s
13 0
0 0
U O
4-1
•r-l
12
in in o
CM in m
4-1 <^— /
c
o
u
0
00
CO
r-l
O
4-J
13
O
o
CO
0)
m
i
•-i
CO
[1
CO
o
o"
r-l O
O O
4J "^Ls
C
O
x^-
ON
CO
4-1 i-l ^—<
3 O O
OHO
43 4J O
4J (3
•r-l o ^-^
^ O
in m O
CN i-~ in
O
H
CD
13
O
in
o
•g
o
4J
CD
T)
C
CO
•i-l
r-l
Cd
4-1
O
H
358
-------
M
S
W
H
Q
h^
<^
tj
J2
M
ts
W
!3
Pi
O
CM"
H r-
W ON
W i-l
Ex< ^^
CO
W
U
3
PQ
.
CO
l~~
1— 1
CU
T-l
f>
CO
H
CO
o
S-l
4-1
C
O
U
cu
4-1
VI
CU
,_!
<^
1
CM
CU
CO
«
O
co
i-H
O
Vi
4J
C
O
O
4-1
CO
CU
PQ
1
r-l
CU
CO
CO
U
CO
o
W x^
C 0
0 0
O 0
J2 ^
•i-l
ts
CO
4J
CO
O
CJ x^
0
r-l O
O O
Vi
4-1 N— ^
c
o
U
CO
1
O
Vi
4-1 /—,
C 0
0 0
cj o
J! "-'
4-1
•i-l
^
CO
4-1
CO
O
U x->
O
r-l O
O 0
}_| U X J2
0) 3 -H 4-1
CO U PM O
co
Assets
CO
4-1
o
H
CO
Q) T3
•H 4J 0)
4J C VI
•r-l 01 Vl
r-i t-i cu
rO 3 CU
CO U O
CO
cu
•H
4J
•H
i-l
•H
rD
CO
•H
rJ
I— 1
CO
4-1
O
H
•£
Vi
o
is
4->
cu
z
CO
CU
•rl
4-1
•t-l
r-l
•i-l
rO
CO
•H
r-l
1— 1
CO
4-1
O
E-i
c~]
4J
Vl
o
IS
4-1
cu
13
C
CO
359
-------
CO
I-l
0
4->
0
0
O
0)
4-J
cd
g
(U
4J
i-H
<«
1
CN
0)
CO
cd
O
CO
I—I
o
M
4J
c
o
U
"5
j^
CO
4-1
CO
O
U
I— 1
o
4J
c
o
o
o
o
^
s-*,
o
o
o
**-S
o to o u"i
Is*"- 10 co to
cvi co r**« co
o m m o
i-i
^^
o m o
r» -* co
CN -d- (•-.
*i n
-d- m
m
o
CN
o m m o m
r-l CO
•H O v-'
^ U
o o o
r~ o co
CM o r--
-------
Construction Cost Per Bushel of Capacity
Country elevators:
Case 1 - Best controls
Case 2 - Alternate controls
Without
Controls
($/bu)
1.15
1.15
With
Controls
($/bu)
1.34
1.31
Increase
($/bu)
0.19
0.16
16.4
14.0
Inland terminals:
Case 1 - Best controls 1.20
Case 2 - Alternate controls 1.20
Port terminal:
Case 1 - Best controls 3.00
Case 2 - Alternate controls 3.00
1.27
1.26
3.09
3.07
0.07
0.06
0.09
0.07
5.9
4.8
3.0
2.4
The financial impacts of the pollution control costs as applied to
the model plants are summarized in Table 175.
The Economic Research Service, as part of their annual survey of
grain elevators, has provided dataft' on the investment and operating costs
for total dust-control programs for 37 terminal elevators. Included was
information for relatively new facilities as well as facilities which are
30 to 50 years old. In most cases, the data reflect a total dust-control
program; however, the equipment is not necessarily the "best" control which
is specified in the model plants. A comparison between the ERS and model
plant data developed in this study is provided in Table 176.
For both the inland and port terminal, the investment and annual
operating costs in the ERS survey are lower than the costs of new model
plants using best controls (Case 1) and higher than the costs using the
alternate control system (Case 2).
Application of Controls to Existing Elevators
In assessing economic impact of air pollution control we have used
the concept of "model plants" to represent the construction and operation
of new establishments. However, the cost and corresponding impacts for
similarly equipping an existing facility with control equipment also needs
to be determined. The total economic impact on grain elevators will be
361
-------
CO
j"y|
o
H
w
w
i_J
w
Q
O
s
§
^:
o
H
O
W
r-l
^
PH
PH
J3
O
Pi
2J
O
o
o
£_(
u
PM
a
o
rH
0
CJ
w
•
m
r-i
cu
1-1
r*t
cfl
H
--. 0
r-l
§
•1-1
cu
H
4J
J_l
O
PM
Ql
cu
CO
cfl
u
I
in
in
CO
COI
Ol
CO
CO
CJ
o
CO
00
M
^
*v
xj-
in
CO
^
rl
O
4-1
Cfl
(LI
1~H
W
,>
r-l
"g
3
O
rs 1
CM
cu
CO
cfl
CJ
CM
vO
CM
n
a
OO
•CO-
^_
cfl|
1-1
CU
CO
CO
CJ
CD
o
N^
CJ*\
•co-
1 i
C
1
4->
CO
CU
C
H
r-l
O
4-1
C
o
CJ
gvg
|
•o
•
oo
o
r^^
•
m
o
r-i
•
t^
o
•
vO
r— 1
O
oo
00
rM
r^
4-1
•rl
O
CO
a
cfl
CJ
r- {
CU
Si
co
3
PQ
^i
cu
PM
O
00
o
o
1— 1
•
rM
O
•
!— 1
•o-
*H^-
•
CM
•o-
o
•
00
•o-
as
rrj
CU
rM
13
C
W
rM
CU
r"]
CO
3
PQ
^
CU
PH
0
Oj>
„
r-H
p^
•CO-
0
CM
M
vO
O"N
•C/3~
oo
CO
CM
M
r-
m
•co-
00
CO
CM
»v
in
r*^
•co-
co
CM
vO
•\
*M^-
1— 1
•CO-
CM
VO
i— 1
•co-
co
4-1
CO
O
60
C
4-1
cfl
cu
a,
o
t— >t
o
4->
C
0
o
1— 1
cfl
3
C
C
<3
H
1— I
r~-
O
gvg
vO
•
O
B*2
r-l
•
, — |
gs2
• Hf
•
i — I
B-S
oo
•
CM
6-5
CO
j^
4-1
rl
O
JS
VI
cu
^
M-l
0
4J
C
cu
CJ
rl
CU
84
OO
1— 1
o
B-S
00
•
o
B~S
m
in
CD
g^
CM
r**»
•
0
B-S
«^f
•
i— I
S-2
f**
^
CO
4J
CU
CO
CO
^
I— 1
CO
o
H
l)_l
o
4J
C
cu
CJ
^4
cu
PM
•o
-*
r-l
0
•
r-l
o
1— 1
•
1— 1
•o
m
•
r-l
0
OS
•
CM
•O
m
CO
r*^>
4J
•i-l
CJ
Cfl
a
CO
o
r-i
cu
r"j
CO
3
pa
}-4
cu
PH
O
OO
N
H-l CJ
r-l iH
CU CU
e e
o o
TJ 13
cu cu
M ^
cx ex
CO CO
•H -H
r-l CM
CU CU
CO CO
cfl cfl
U O
S-i M
O O
M-l M-l
•U 4-1
C C
cu cu
It
•r-l •!-!
3 3
cr a1
w w
o o
M ^
4-1 4J
C C
O O
u u
362
-------
CO
H
CO
0
U
I-H
8
H
0
U
J.
jS
^
H
U
§
tx
rl
S>
f^
S
CO
CO /—>
NTS AND ER
ELEVATORS
J M
PL,
O
CT>
0
•
>•.
J-J
•H
O
cd
CX
CO
O
0)
00
cfl
}-l
o
CO
4J i+-l
C 0
01
S *-*
JJ 0)
CQ x:
0) CO
> 3
C PQ
H~l
r-l CO
co PM
4J
O
H
CM
o^
•
O
oo
o
I-l
1-1
•
r-4
I— 1
(-«.
•
I— 1
r-l
*
r-l
m
•
O
I— 1
""O
a
c
•H
co
O
M-l
O
i— 1
0)
CO
3
pa
M
O)
PH
4-1
co
0
U
60
C
•H
Cfl
01
ft
O
r-l
CO
C
C
O CM
O CM
• •
CM O
ro oo
*«^ 1—-4
• •
r-l O
CM <(•
CT\ CM
r-l O
r-l r-l
CM *si*
• •
r-l O
-------
significantly different if control regulations are applied to existing
facilities rather than only to new facilities. To evaluate the impact
for both cases, we have estimated the control costs which would result
from installing the best control equipment on an average existing facility
and have extended the results to determine the total impact on all ele-
vators .
The major assumptions and estimations which were made in determining
the impact on existing facilities are listed below.
1. The size and type of pollution control equipment required for
each type of elevator—country, inland terminal and port terminal—will
be the same regardless of elevator size. This estimation is based on the
fact that the control equipment required for an elevator is primarily
dependent upon the basic operations which are performed by the elevator
rather than upon its size or volume. Also, the available facilities and
operations performed by the model plants represent an average country ele-
vator, inland and port terminal. Some existing elevators will have more
facilities than the model plants and will require additional controls
while others will have less.
2. The cost to install the control equipment on existing plants is
130% of the cost required for a new plant if the existing plant currently
has no controls. The cost to install "best" control equipment is 110% of
the new plant cost if the existing plant has cyclones. The increased
costs to existing facilities reflects the fact that the retrofitting of
ducting and equipment would increase the installation charges. No cost is
required if the elevator already is equipped with adequate control equip-
ment.
For each of the three types of elevators, the percent of control on
each operation is given in Tables 177, 178 and 179. The percentages were
obtained from the emission inventory survey which was conducted as part of
this project. The average percent of existing controls on the receiving,
shipping and handling operations is 26.4% for country elevators, 44.3% for
inland terminals and 52.97° for port terminals.
A summary of the costs and control credits resulting from the instal-
lation of best control equipment on the average existing elevators is
presented in Table 180.
The investment required on the country elevator for best available
controls is $117,000—24% greater than for the new model plant. The in-
vestment required for alternate controls is $84,000 or 28% less than for
best controls.
364
-------
1— 1
o
CO
H
a
•^ CO
pj t"-*
pi P^ i
O CN
H O t^
"^4 a CJN
> M i-l
W H
1-4 CO •>
W M CO
XI H
>> w a
Pi -i
o> a i>
.-H o pi
Xl M £=>
n! EH co
H i=i
jj
t— 3
0
P-i
S-i
5-S 4J
c
i— 1 O
to CJ
4-1
0 XI
FH 4-1
•r-l
^
r^ oo oo
• • •
o i-i m
CO CN CN
to
4J
s-i c
to 01 CO
Ol XI Z ^-l
Ol O
r**- ^o i^
i— i
Q
U 1-1
Ol O
X! H
4-1 4->
O B~S C
O
CJ
CN l~~ 1 —
o -t 3
1 1— 1
a o
S-i
4-1
*^o r^
B^- *~"
0
o
in o> vo
vO CN O
ON i-H 00
CN CN i-H
to
4-1
}-! C
XI i-H
i3
S3 M-l
0
st sf r~N
CN CN CO
CO CO CN
/*-x
i-l Ol M 3
CS S >* X)
4-1 3
O i-l S-i O
EH O 0) O
> P-i O
^-^
CO si- O
CN CN VO
00 _ -H 60
•r-i a, a
01 Oc -H
O -H >-.
QJ r** ^
{Vj CQ f^
CO i-H O^ CTN
• • • •
CO P1*- vO CO
r^ cs CNJ m
I-l
o
l-l
4-1
c
0
u
CO
•1-1
XI
o
•1-1
XI
J5
c
o
•H
CO
01
Ou
o
Ol
X!
4-1
t-l
o
M-l
^9-
jj-'
•H
4-1
n
CO
3
cr*
I— 1
CO
4-1
o
4-1
Ol
XI
4-1
14H
o
Ol
60
CO
4-1
c
01
u
S-i
Ol
ex
Ol
X! Ol
44 O
'' -H
CO >
•H 0)
'O
I— 1
O 0
SH *t-4
4-1 M-l
C -H
o u
O Ol
a
4-1 CO
c
Ol 0)
0 JS
)4 4J
01
PH
-*^^1
C0|
365
-------
6-5
r-H
CO
4-1
O
H
T—t
O
1H
4.1
C
0
f~i
4-J
•H
r- co CM
t • •
oo o H C
cu to
E P-4
3
S 0
r-H
^
O
r-l
CM m
r-4
,-H
O
r4
6-S -I-1
c
o
u
CO
4-1
!H C
cu tfl
-9 '~l
c n .
C3 r^-l
3
12 i_l_l
CM in
CO i — 1
• •
ON r^*
r-l r-H
O r-l
m CM
"^
o
f-2 4J
C
O
u
CO
4J
SH fi
CU CO
fi r— 4
6 PH
•a MH
O
r- oo
CO O
ON CM
CO i-H
vO vO
ON ON
r-4 r-4
a
o
•rH
0)
a
o
CM
CO
o
CO
CM
m
00
ON
co
v£>
CU
13
O
•H
MH
•H
O
cu
ft
CO
01
4-J
366
-------
C/3
c/> H
PS 5
O <
1
W O CM
i-J !3 r-
W M ON
H T-l
H cfl
p> M -
0 X OT
PM W H
S| 0 3
& PM
M CO
g HM- CM
OS O r-l
[VJ rvj
H H P*
^ o
O
• O >-f
ON EL)
^ r^i t>
<-t o P4
M p
ci) H CO
-1 p
.a hJ
rt tJ
H O
PM
i— 1
O
S-S 4J
Ci
i-H O
co o
4J
o ,e
PH L1
•T-l
IS
00 00 ^ ON T—I i— i ON
OOr-^OCMrH •sl'-d'CM
• •••• •••
in in CM t**- CM co co i^
r-cMincooo vooin
M
CU
O
'•:,
CU
Q
M
CU
rj
4-1
O
CO
4J
H fi
cu CO
rO 1— I
E PM
^ 'II
O
ooooo ooo
, — {
O
M
4-1
B-S fl
0
0
ooooo ooo
CO
t-l
4-1
i-t
•i-l
PM
CJ
•1-t
$H
43
PM
CO
4J
J-l fj
cu n)
,0 r-l
H PM
3
IZ 4H
O
o o o
o
CO
) 1
SH C
CU CO
O f—j
6 PH
a 4-1
0
VO0 JH CO
••-I R a -H (JO -H 4-1 h i— 1 a)
•i-tfliCCcocUcO ft
CUft-HCOCCO WfX
O-H >, >
4J
•H
4-1
c
to
3
cr
, — i
to
4-1
0
J-l
CU
43
4-1
4-1
0
CU
Ml
CO
4J
s
CU
o
M
CU
CU
42 CU
4-1 O
•H
CO >
••H CU
1— 1
O O
0 i!
O CJ
CJ CU
ft
4-1 CO
c
cu cu
O £
)H 4-1
cu
PM
-•^
<0|
367
-------
8
*>
t-3
J3
H
CO
M
X
pa
w
o
s
u
I--*
o
H
O
hH
£
•"^
(-!
O
g
0
o
CO
t"'
i — i
o
g
u
I-J
0
g
s
O
U
§
B
en
O
u
o
oo
CD
1
H
CO
C2
•H
6
t-i
0)
H
,2
CM O
cn
QJ CO
") CM
o m
r-t CO
QJ CM
CO ••
co o
CJ CM
«•
rH
c
•H
B
0)
H
•a
c
CO
I— 1
c
M
^i
O
4.)
CD
^
CD
^
£?
4-1
C
§
CM r^
0) S
0) «t
(C vD
o r^
CM
CO «
O vD
CM
O
i— i
tn
4-1 OJ
to co
O C co
U QJ (U
CL co
1-1 X C
1O
R
"
r^-
«-
CM
CM
V>
CM
CM
CM
v>-
o
CM
fr
G
C
<£
,— t
to
4J
O
H
OO CM
a\ oo
CM" CO
CM -
i— 1 1^
o\ in
ci c
0 0
4J 4-1
1-1 1-1
4-1 i-« m
•H 1
13 1
a) p",
O Ol
i-l O
O O
I-. CD
4J ffi
c
o
m o
o' o
in CN
rH O
•-i oo
CN ^
O O
e .-i
C CD PM
I-l O
V4 S
1-1 a) cu
o PI a
4-1 CO ^1
C CO O
O 4-1
CJ 4-1
C
r-< CO
m o
in CN
OO 00
r^
Control
ing, Han
o
p
C0l
368
-------
The control credits are less than for the model country elevator because
of the presence of existing controls and smaller volume of grain handled.
The net annual control cost per bushel handled is 2.55<: with no recovery
and 2.49c with maximum control credit of 5 Ib/ton.
The investment of $368,000 for best available controls on an average
existing inland terminal is 47o greater than required for a new plant.
Alternate controls on existing inland terminals require investment of
$277,000--25% less than best controls.
For existing port terminals, the average investment in best available
controls is $420,000. Alternate controls would require an investment of
$153,000 which is 64% less than required for best controls.
The impact associated with the average existing plants were expanded
to include all country elevators, inland and port terminals. The result-
ing total economic impact of pollution control on the industry is summarized
in Table 181. The numbers of elevators registered under the Uniform Grain
Storage Agreement—7,147 country elevators, 413 inland terminals and 64
port terminals--were used to arrive at the total impact figures. Since
not all elevators are registered, the total impact is somewhat understated,
particularly for country elevators.
The total investment for the best available control equipment as
shown in Table 181 is $1,015 million. Because of their large numbers, the
country elevators required 836 million or 827° of the total. The total in-
vestment in alternate controls is 2870 less than for best controls.
The annual control cost of best controls for the industry is $188
million. The installation of alternate controls reduces the annual con-
trol cost by 327o to $129 million.
Economic Impact on New Plants
If the air pollution control requirements were applied only to new
grain elevators, then the total economic impact would be minimal, simply
because there are few new elevators being built. A small number of country
elevators have been built during the past few years in the corn belt and
in the Southeast. In addition, a few port terminals have recently been
built or are under construction. However, according to industry sources,
there is sufficient, and in some places,excess capacity at the present time
and few off-farm elevators will be constructed in the near future.
369
-------
Table 181. TOTAL ECONOMIC IMPACT IF APPLIED
TO ALL EXISTING ELEVATORS
Country elevators
Inland terminals
Port terminals
Total
Annual Control Cost
Case 1 Case 2
(OOP) (OOP)
$150,659 $105,561
31,892 21,564
5,922 1.779
Total Investment
Case 1
(OOP)
$188,473 $128,976 $1,014,797
Case 2
(POO)
$835,942 $603,064
151,958 114,235
26,897 9,781
$727,080
370
-------
From an analysis of the model plant financial statements, it would
appear that the installation of control equipment on inland and port
terminals will have an impact. However, the investment and annual costs
for the specified control systems will not significantly affect the opera-
tions or profitability of a new terminal elevator.
The impact of control requirements on new country elevators will be
greater than for terminals. If control requirements are applied only to
new elevators, then the additional costs will generally have to be absorbed
by the country elevator because of the competition from existing facilities,
Clearly, the economics of scale for elevators will change. The in-
vestment in control equipment remains basically the same for a country
elevator of 200,000 bu storage capacity as for one of 700,000 bu. For the
500,000 bu model plant, the investment in best-control equipment was 14.1%
of the total construction cost of a 200,000-bu elevator. As a result of
pollution control regulations, large elevators will tend to be more eco-
nomical than smaller ones.
Because of the investment required for control equipment and the in-
crease in economies of scale, the capital required to build and operate a
country elevator will be significantly greater than in the past. As a
result, the smaller independent firm will be less likely to have the neces-
sary capital to build new elevators. The existing trend toward ownership
by cooperatives and integrated corporations will be increased.
Impact on Existing Facilities
The economic impact resulting from the application of air pollution
control regulations to existing grain elevators will be much greater than
if regulations are applied only to new plants. By far the greatest im-
pact will be to existing country elevators. The impact on inland and port
terminals, although less than country elevators, will still be significant.
Impact on Earnings - For the average country elevator the annual cost of
the best available pollution control is 2.55c/bu handled and the net con-
trol cost using maximum recovery credit is 2.47c. This compares with the
present average net margin of 2.82c/bu. An 87% reduction in net income
would occur if the control costs were absorbed by the country elevator.
Since the profitability of country elevators is already low, these costs
must be passed on to the consumer or back to the farmer. Historically,
most cost increases in the grain distribution system have been passed for-
ward, as in the case of increased transportation expenses. It is ex-
pected that pollution control costs will also be passed on to the consumer;
however, because of the constant fluctuation in grain prices, it is pos-
sible that some of the increase could be passed back to the farmer.
371
-------
The small country elevator which handles less than 500,000 bu/year
will be even more severely effected than the average or larger country
elevators. This impact can be illustrated by the fact that an existing
small elevator even without a dryer would still require an investment of
$96,300 for best-control equipment and corresponding annual operating
costs of $17,100. If the elevator handles 200,000 bu annually, the con-
trol costs are equivalent to 8.55c/bu. This compares with 2.55c/bu cost
for an elevator which handles 1 million bushels annually, a difference
of 6<;/bu. Because of the competition which exists, some of these small
elevators will have to absorb most of this difference in order to remain
competitive and maintain their volume. However, with an existing average
net margin of only 2.8c, they will not be able to absorb 6c/bu additional
costs and remain profitable. A number of small elevators will be forced
out of business if the best available control equipment were applied to
all emission points.
Requirements for the installation of the cyclone-based control sys-
tem (Case 2) on existing country elevators will still have a significant
economic impact; however, the impact will be less than for best controls.
For an average existing elevator, the installation of the alternate con-
trols will require an investment cost of $84,000 which is 28% less than
the investment required for best controls.
For the average inland terminal, the annual cost of the best available
pollution control equipment using maximum recovery credit is 1.61c/bu
handled. Since the average net income per bushel is around 1.60c, the
control costs cannot be absorbed and will most likely be passed on to the
grain consumer. As is the case with country elevators, the pollution con-
trol costs per bushel will be greater for the smaller inland terminals.
Since some of the inland terminals are marginally profitable or even un-
profitable at the present time, it is possible that a number of terminals
could go out of business rather than install $368,000 worth of pollution
control equipment.
The installation of the alternate control system (Case 2) on an
average existing inland terminal would require an investment of $277,000,
which is 25% less than for best controls. The annual operating costs for
the alternate control system is 1.17c/bu handled or 33% less than for best
controls.
The economic impact of the best-available pollution control equipment
on port terminals will not be as great as for inland terminals. For the
average existing port terminal, the annual cost of best-available controls
is 0.18c/bu if maximum control credits are used. This compares to an
average net income per bushel without controls of around 1.25C.
372
-------
The impact of the alternate control system on existing port terminals
would be minimal. The installation cost for alternate controls would be
$153,000 or 647o less than for best controls, and the annual costs would be
0.07<:/bu handled or 70% less than for best controls. The impact of instal-
ling alternate controls on existing port terminals is significantly less
than for best controls,primarily because many of the port terminals already
are equipped with control equipment adequate to meet the specification.
In either case, the port terminals are in a position to pass the in-
creased costs on rather than absorb them.
Demand Elasticity - Country and terminal elevators have historically been
an integral part of the nation's grain distribution system. As such,
demand for their services as a group will be relatively inelastic with
regard to price. Elevators should be able to shift most of the average
control costs into price increases without adversely affecting demand. How-
ever, there are a number of factors which will tend to reduce demand as
prices increase.
First, because of competition the demand for an individual elevator's
services will be sensitive to price changes. Therefore, an elevator will
not be able to pass on cost increases which are above the average per bushel
costs for competing elevators without affecting demand.
Second, there is enough flexibility in the distribution system so that
the demand for services from a particular type of elevator can be moderately
changed. For example, it is possible that an increasing number of farmers
will bypass the country elevator and deliver their grain directly to proces-
sors, subterminal or terminal elevators. The possibility that farmers can
economically bypass the country elevator has increased as a result of addi-
tional on-farm storage facilities which have been constructed during the
past decade.
Also, it is possible for the country elevator to bypass the inland
terminal and ship grain directly to processors and port terminals. This
capability will increase if country elevators become larger or if smaller
elevators cooperate with each other to obtain train-load rates from the
railroads.
A third factor contributing to demand elasticity is international
competition. If the control costs are reflected in the price of grain,
the relative competitive position of U.S. grain and grain products on the
world market will be affected. The 3 to 4c/bu increase in the price of
grain resulting from pollution controls could reduce U.S. exports. The
increase in price may not significantly affect grain exports during periods
such as the past year, when world-wide demand exceeds available supplies.
373
-------
However, during years when world supply exceeds demand, U.S. exports of
grain may be affected by increased prices.
Effect on Industry Structure - The placement of control regulations on
existing facilities will have a significant effect on industry structure.
The number of independent firms will be reduced because of several factors.
First, some of the small country elevators operated by these firms would
not be profitable with the installation of control equipment. Second, the
small firm may not be able to obtain the capital required to install con-
trol equipment. Because of the marginal profitability of existing facili-
ties and the minimum salvage value of an elevator, many of the large com-
mercial banks would not provide the necessary capital to a small country
elevator.
Large integrated firms and farmer cooperatives will have less problems
in obtaining capital. However, they may determine that an elevator will
not be profitable with the investment required in control equipment, and as
a result will close the elevator. A major problem which large firms may
have,results from the fact that several terminal elevators are owned by
second parties and leased to the operating company. The owners of these
facilities may not be willing to invest in pollution control equipment, in
which case the operating company may be forced to purchase the elevator as
well as the control equipment in order to remain in operation. A few marginal
terminal elevators could possibly be forced to close.
FEED MILL
Description of Model Plant
A schematic diagram of the model plant for a feed mill with best con-
trols is presented in Figure 55. The processing capacity of the mill is
assumed to be 200 tons/8-hr day or 50,000 tons/year. The model for the
feed mill is patterned after a similarly sized unit described in Ref. 14.
The specific processes shown in Figure 55 are not meant to fit any specific
feed mill. Individual feed mills may vary both in processing steps and
operating characteristics. In addition, the size of feed mills covers a
wide spectrum, from under 1,000 tons/year production to over 100,000 tons/
year, and operations vary with size. Accurate representation of the multi-
tude of feed mill sizes and configurations would require an extensive
series of models. Such a detailed study of one segment of the grain and
feed industry was deemed inappropriate in this program.
374
-------
o
o
o
X
0
-
o
E
CO
Q
LLJ
§ s S.
§
o
i
, i
8
CN ^_
£•'0
o 8.
8.8-
o
(J
-------
Control Equipment Costs
A summary of two alternative control equipment configurations and
associated costs required for the model feed mill is presented in Tables
182 and 183. The control equipment in Case 1, which consists of fabric
filters for all grain-handling operations, is the "best" demonstrated con-
trol system currently available. Case 2, which specifies cyclones for the
grain-handling operations, generally reflects the current industry practice
for feed mills which have installed pollution control equipment. Estimates
are given for the investment cost for control devices for each operation,
as well as estimates for the total annual cost, including electrical charges,
maintenance expenses, depreciation expenses and capital charges.
The operational hours per year were estimated from an analysis of
(1) the operational requirements and capacities of each device, and (2)
the volume of material which would be processed by each operation. Assump-
tions regarding electrical, maintenance, depreciation and capital costs
were discussed in the introduction to this chapter.
A summary of the investment and annual operating costs required for
both pollution control equipment alternatives is as follows:
Pollution Control and Product
Recovery Equipment
Total Annualized Total Installed
Primary Device Cost ($/year) Cost ($)
Case 1 - (Fabric filters) 44,035 196,370
Case 2 - (Cyclones) 35,609 158,680
If the grinding operation uses air for product transfer, then the
selected control device listed in the model plant for this operation
actually functions as a product recovery device rather than as a pollu-
tion control device. In this alternative, the estimated investment and
operating costs for pollution control equipment are as follows:
Pollution Control Equipment Only
Total Annualized Total Installed
Primary Device Cost ($/year) Cost ($)
Case 1 - (Fabric filters) 40,255 181,570
Case 2 - (Cyclones) 33,197 149,880
376
-------
O
O
i Is
377
-------
c o
M O
&0 -co- w
d
•r-l I 00
> d
H T3 -i-l
01 0) T>
O J^ CT3
I OJ W O
>
5ra
p.
378
-------
Credits for Dust Control
The wide range of materials received, conveyed, and processed at a
feed mill make it difficult to determine control equipment credits or
positive impacts which could result from the installation of high-efficiency
pollution control equipment. Lack of emission factor data for feed mill
processes also hinders such determinations. In addition, cross-contamina-
tion of materials is avoided in feed mill operations and, therefore, a
significant portion of the recovered dust may have no real value unless
the dust from different sources is segregated. For these reasons, no
attempt was made to compute credits for dust control in feed mills.
Financial Statements
Income statements and balance sheets for the model feed mill are
presented in Tables 184 and 185. Separate financial statements were de-
veloped for the operation of the model plant}both without and with the two
alternative pollution control systems. These statements were compared to
determine the impact of the control equipment on the financial condition
of new plants.
The financial statements were developed using information from the
1970 Annual Survey of Manufacturers,!^' 1967 Census of Manufacturers,!*!/
USDA Economic Research Service Data,!!/ the 1972 Annual Statement Studies
by Robert Morris Associates,—' and financial statements from various
publicly owned feed manufacturing companies. The financial condition of
feed manufacturing companies can vary significantly by company and over
time; therefore, the statements presented here should be considered as ex-
amples which reflect general financial conditions of the industry. Be-
cause of the unprecedented changes in grain and feed prices since the last
half of 1972, the financial conditions of many feed companies have been
significantly altered during the past year. In an attempt to reflect
these changes, the income statements and balance sheets were developed
using the grain and feed prices during the first quarter of 1973.
Average price of poultry and livestock feed in 1970 was $90/ton
according to data from the 1970 Annual Survey of Manufacturers. However,
by April of 1973, feed prices had almost doubled and the prices were still
increasing. In developing the income statement, it was assumed that the
price of feed was $178/ton and the average price of ingredients was
$149.50/ton. These estimates were obtained by proportionally increasing
the average sales and cost of materials prices from the 1970 Annual Survey
of Manufacturers^?./ to reflect commodity prices during the first quarter
of 1973.
379
-------
3
s
o
w
fn
i-5
W
8
^
§
o\
/-s
is f^
IS rH
W ^-^
^
H
U}
0
u
s
^
CO
i-H
CU
I-H
tO
H
CO
o
4-1
C
O
CJ
CU
4J
to
C
u
CU
4_J
rH
cn
O O o
0 O 0
\O vO CO
*t n n
I-H
co r^-
0\ r-4
o
o
>o
tn
cn
CN O>
r-H r-H
i-H
O O «d" 5^5 i5^
o o cn vo '•o
- *"*
ir\ T — i
CTi c*-J
C co
CO O 4J
CU CO -rl CU
CO ClJ 4J J2 CO
C ^ O -U M
0) OJ 3 rJ
-------
CO
00
o o
o vo
o
o
CT> i-l CO to CM
i—H vO in CO 00
I—I I—I CO r-l
o
o
o
p
o o o o
o o o o
ON
.c
a) co
en tJ
en a)
Q) 0) to -i-l JD
J3 4J
CO O
&*
Pn S
CO 0)
^7
3 4J
O 1^
O O
o ss
0
H
o
H
ffl
•i-l
iJ
4-t
d
0)
M
t4
tu
Q
^ 3
CO u
O
H
O
H
,£>
CO
O
H
C0|
381
-------
Economic Impact of Control Systems on Industry
New Plants - Separate analyses were made to determine the impact of pollu-
tion control equipment on the model feed mill for: (1) pollution control
and product recovery equipment, and (2) pollution control equipment only.
In the latter case, the control device for the grinding operation was not
considered as control equipment.
As shown in Table 184, the net income before taxes per ton of produc-
tion with and without pollution control equipment is as follows:
Pollution Control and Product Recovery Equipment
Net Income Net Income
Without Controls With Controls Reduction
Primary Device ($/ton) ($/ton) ($/ton) (%)
Case 1 - (Fabric
filters) 4.22 3.34 0.88 20.9
Case 2 - (Cyclones) 4.22 3.51 0.71 16.8
If the control device on the grinder is considered to be a product recovery
system rather than a pollution control device, then the impact of pollution
control regulations on net income before taxes is as follows:
Pollution Control Equipment Only
Net Income Net Income
Without Controls With Controls Reduction
Primary Device ($/ton) ($/ton) ($/ton) (%)
Case 1 - (Fabric
filters) 4.14 3.34 0.80 19.3
Case 2 - (Cyclones) 4.17 3.51 0.66 15.8
The installation of fabric filter control equipment could reduce the
profitability of the model plant by 19 to 21%, while the installation of
cyclones could reduce profitability by 16 to 17%.
382
-------
The balance sheets in Table 185 show the financial position of the
model plant without and with pollution control equipment for both control
systems. The impact on a new model plant of the investment in control and
recovery equipment on the construction cost per ton of yearly capacity is
as follows:
Pollution Control and Product Recovery Equipment
Plant Plant
Investment Costs Investment Costs
Without Controls With Controls Increase
Primary Device ($/ton) ($/ton) ($/ton) (%)
Case 1 - (Fabric
filters) 23.40 27.35 3.95 16.8
Case 2 - (Cyclones) 23.40 26.60 3.20 13.6
If the control device on the grinder is considered to be a product recovery
system rather than a pollution control device, the impact of the invest-
ment in control equipment is as follows:
Pollution Control Equipment Only
Plant Plant
Investment Costs Investment Costs
Without Controls With Controls Increase
Primary Device ($/ton) ($/ton) ($/ton) (%)
Case 1 - (Fabric
filters) 23.70 27.35 3.65 15.4
Case 2 - (Cyclones) 23.60 26.60 3.00 12.7
In Table 186 the control investment and annual operating costs for
each alternative are compared to standard operational and financial sta-
tistics for the model plant.
From an analysis of these data it would appear that the costs associated
with the installation of pollution control equipment will not have a sig-
nificant impact on new plants in the size range of 200 tons/day and above.
383
-------
rJ
rJ
M
&
P
W
W
&H
ed
o
PM
3
,.4
H
P
o
g
|S
M
^
0
H
P
PM"
M
HJ
PM
PM
<
CO
rJ
O
o!
H
2;
0
O
•
vO
00
, — 1
01
1— 1
,0
cd
fn
r— H
o
rH >•
4J rH
d d
0 0
CJ
4-1
d d
o cu
•rl S
•u &
3 'rl
rH 3
rH CT
O W
PM
/^N
01
d
o
r-l
O
>
o
%_x
CN1
cu
co
cd
CJ
o
OO
co oo
r-» •>
(Ti C^
r-l -
^" N
S-i
01
4J
i — 1
•rH
4-1
u
•rl
rH
JD
cd
4H
^ — /
r-H
OI
CO
cd
CJ
4-J
rH d
O CU
rl B
4J 4-1 ft
d o -H
O 3 3
CJ 13 D1
O W
d rl
0 PM >
•rl (H
4J -O CU
3 d >
r-H Cfl O
rH 0
O
O
•*^
CM
0)
CO
cd
CJ
o
i~~-
co m
r— «
O\ rH
r-H OO
r-H
•co-
o
CO 00
|-s. vO
O^ "
rH 00
m
r-l
| cy\
r-H| r-H
•CO-
4-J
d
CU
S
4->
CO
CU
>
d
H
r-l
O
rl
4-1
d
S
6-2
r--
•
CM
i— 1
5-5
CO
•
m
r-H
5--
vO
•
CO
r-H
6-2
oo
•
vO
r-H
4-J
d
i— 1 0)
cd i
d &
•rl -rl
60 3
•H cr
S w
•a
4H fi
o cd
4-1 4J
d d
cu cd
CJ rH
rH PM
cu
PM
tv?
0^
OO
vO
•
r-H
6-2
•st
O
•
CM
6-2
00
l-»
•
r-H
6-2
r-H
CNI
•
CM
CO
0)
r-l
cd
co
rl
cd
rH
r-l
O
P
4-1
O
4J
d
O)
o
rH
CU
PM
O
O
•
CO
u
VH
cu
PM
6-2
vO
O
•
o
g
r-H
•
r-H
5-2
CO
O
•
r-l
&*•£
0
CM
•
r-H
CO
4->
CU
CO
CO
•<
r-l
cd
4J
O
H
4-1
O
d1
0)
u
rl
CU
PH
6-2
r-
co
o
5-2
m
O
M
PH
•U
CU
01
PH
4-1
0
d
0
H
rl
0)
PH
384
-------
However, the investment required for control equipment does not de-
crease proportionally to decreases in plant capacity. An estimation of
the effect of annual costs for "best" pollution control as a function of
plant size is shown in Table 187. The annual cost per ton of feed produc-
tion increases from 88
-------
CO
CO
V
o
•H
CO
OX
•
O
ir,
ca
CO
en
j-i
ca
a
<4-l
Q
en
QJ
O
PM
00
CM
o
ro
vO
o
en
t-<
O
§
55
^^
•
oo
I—I
0)
c
o
u
en
Q)
PQ
0)
en
ca
c
o
•H
4J 4J
CO O
O 3
O T3
^ "S
o cu
CJ ft.
ca o
§ c
C o
0)
ft
00
00
o>
CM
O
LO
1— 1
1-1
•1-1
a
TD
01
CU
fe
M-l
O
tu
N
•H
CO
^~ N
>
tfl
13
^^ —
C
O
4J
^^
o o o
o oo in
CM
386
-------
1
01
1
<
W
£>
P
C/3
'-'
OO
,J
M
S
Q
W
Id
tM
O
1 — i
H
0>
H
XI
W
55
O
en
j
O
p^
F— i
£5
0
u
a
o
M
%
hJ
g
Ci
M
0
^
cMr^ p~O CM oo in CM
OO ON CO rH C7N in O r*^
ONOO cno T-ICDU m ^-^ cu
•Hr-i3 (X >-i 3 CO CU cd| >
cucdvi Cu cd M C Hi co
OUH -t-lOH at j-i oO n
cu J3 l-i cd cu -H
PC! W H O h4 PQ
r^
•
CO
^j-
CO
vO
m
•s^
•
r-H
0
•
3
^
o
o
o
ft
CM
ON
4-1
o
co
4J
&
cu
o
cu
M
'O
a;
00
00
cd
^
OJ
3
CJ
a
•H
4J
0
CJ
co
cu
Q
-—^
«l
387
-------
n
ro
C/3
tJ
M
Q
W
W
O
*z
r— 1
H
C/J
l~~(
X
W
o
H
Q
W
M
PH
PH
C/3
O
H
O
U
"Z
0
r- 1
H
)— 1
PH
*
00
i-H
CU
1 — 1
ft
TO
H
^^
Cfl|
^
4-1
CO
3
a
^
r-l
O
4-1
r-l
cfl
4-1
0
H
CNl
Ol
CO
cfl
U
r-l
01
CO
Cfl
O
4-1
d
Jj
CO
•I-l
1 — 1
tfl
4-1
CO
W
M
OJ
PH
O)
60
cfl
CU
t>
•^
CNl
0)
Cfl
cfl
U
r-l
a>
co
cfl
0
o
o
'•"N
0)
d
o
i — i
o
>-
o
O
O
O
o
«v
CO
r«-
rl
01
4-1
•H
O
•H
M
-Q
cfl
4-1
O
0
O
A
O
o
o
CM
0
r\
r-l
^-4 -co-
^— v
O)
d
o
i— i
o
>
o
x-'
O
o
o
#\
LO
oo
rl
CU
r-l
•H
4-1
U
•rl
rl
CO
4-1
^**
o
o
vO
I— 1
CO
I— 1
i— 1
O
t_ j
4J
d
o
0
rl
0
4-1
4J
d
0)
B
jj
co
cu
^
d
M
O r-l O
o
o
o
0
^
^
ro
r— 1
^n
ro 4-1 O
d d 4-1 d
O O O 4J
o o 4-1 o d
O tl)
i— 1 i— 1 r— 1 O
Cfl Cfl d Cfl S-l
3 30 30)
d d -u d &.
d d d
^
.^
cfl
rS
0) 4-1
B M
43 tfl
co 3
•H cr
^3 U
Cfl CO
4-1 i-l
W •!-!
["T"] JVt
"tfl|r2|
388
-------
For the average existing feed mill, the installation of "best" con-
trol equipment will require $131,600 investment and $25,900 annual operating
costs. Annual control costs are estimated at about $2/ton of feed produc-
tion for the industry or about 1.1% of sales at 1973 prices.
The installation of the cyclone rather than the fabric filter-based
control system will reduce by 35% the required investment and annual con-
trol costs for the average existing plant. The impact of the cyclone system
on existing plants is less because of its lower costs and because a greater
number of existing plants already have cyclones.
The $1 billion investment and $200 million annual control costs re-
quired for the installation of "best" control on existing feed mills will
clearly have a significant impact on the industry. Even the installation
of cyclones will have a major impact. In either case, the impact will be
greatest for small companies and small feed mills.
Demand Elasticity - The total demand for formula feed is closely tied to
the demand for meat and other products from the livestock and poultry in-
dustries. Because of the relatively long lead time required to significantly
alter the number of livestock or poultry requiring feed, the average in-
crease in feed costs will probably be passed on to the customer. However,
over the long run the demand for feed may be adversely effected by in-
creases in price.
The 100%, and greater increases in feed costs which have resulted from
increased ingredient prices from 1972 to 1973 have for the most part been
passed on to the feed customer. However, the poultry farms and feed lots
can choose to reduce the amount of feed used and the number of poultry and
livestock which require feed when a rise in feed prices does not coincide
with an increase in the market price of meats. Complexity is compounded in
that many feed manufacturers are integrated into the livestock and poultry
business, effectively making the feed mill a captive operation. In any
event, the average price increase of 1.1%, required by the best pollution
control is small in comparison to the increases in feed prices which have
occurred during the past year.
Even though the average price increase for feed may be passed on, an
individual plant which has control costs per unit of production higher than
the industry average will in many cases have to absorb the additional costs
to remain competitive with other feed mills. Unless the small feed mill
has a captive customer or has significant transportation advantages, it will
have to absorb most of its pollution control costs (see Table 187).
389
-------
Effect on Industry Structure - Regulations requiring control equipment on
all new and existing feed mills will have a major impact on industry struc-
ture. New feed mills, because of changes in economics of scale resulting
from installation of control equipment, will be larger than most existing
establishments. The increased capital requirements for a new plant will
tend to limit the number of new mills which will be constructed by small
companies.
The impact on existing facilities will be even greater than for new
plants. Many of the small feed mills operated by nonintegrated companies
will not be profitable with the installation of control equipment. In
addition, the small firm will be less able to obtain the capital required
to install control equipment than the large integrated firms and farmer
cooperatives.
Of the 7,917 establishments producing 1,000 tons or more per year,
75% or 5,952 produce less than 10,000 tons/year or 40 tons/day. A number
of these small plants would be forced to close if required to install pol-
lution control equipment.
ALFALFA DEHYDRATING PLANT
Description of Model Plant
Figure 56 presents the model selected for the alfalfa dehydrating
plant. A plant which uses a wet scrubber for the dryer-cyclone operation
and a fabric filter for the grinding operation was selected as being
representative for a new facility in this segment of the grain and feed
industry. An alternate model with a cyclone on the grinding operation is
also analyzed. Plant capacity is 3.5 tons/hr of dry meal or pellets and
the plant operates 2,400 hr/year to produce 8,400 tons of product.
Control Equipment Costs
A summary of two alternative control equipment configurations and
associated costs for the model plant are presented in Table 190. Esti-
mates are shown for the investment cost for the control device, as well as
the total annual cost, including electrical charges, maintenance expenses,
depreciation expenses, and capital charges.
Summarized below are investment costs and annual control operating
costs for both alternatives:
390
-------
o
U
D
O
-
O
O)
c
o
S-J
4J
c
o
o
to
(U
C
n)
a,
w
U
0)
O-
"u!
o
cfl
0)
Q.
D
s.
k.
Q
0)
_Q
_Q
O
CO
"ai
i
CO
c
o
h~^
• r
00 i
1 O
>-2
-C^''*
'n ^
O
Q- I
u £
o
-*_ i_
C 0)
0 Q-
5:0
r-l
cd
ctf
,-1
cu
T3
O
bO
a
CO
391
-------
13
O
I-l
H
M
Q
PH
us
H
0
^J
fe
•
30--.
C
< n
r-l CO rl
cd cu cd
4-1 bO cu
•rl rl >,
CX Cd -•-.
cd X!
O O s_.
c
o
•rl /->
4-1 T 1
cd cd
•H CU
0 >-
i-l
a s_
CU
o
O 0 0
000
O 00 00
o -j- ~a-
a -«.
•rl
^
o o o
in o in
oo m en
i— i
r-l
Cd /-s
0 rl
•rl Cd
rl CU
O --
CU -CO-
r-l X- '
fa-
0 01 0
o ol o
r-- col o
A *J «t
I—I r-l CO
G /*~N
0 rl
•H Cd
4-1 CU
cd >
CU i-l
CX XI
O N-
O O
O O
CM CM
o
1— 1 ^
fa B
•S-t 0
•rl s_/
O 0
O O
O O
m m
CM
^
CU
a) cu
4-1 0
O -rl
CU >
r-l CU
11 Q
co.
XI rl
3 0 CU
0 rl -rl
cu cd
13 fa
CU
c
G
o
4_J
cd
cu
a
O
r-i
O
u" G°
•rl
^ -d
CU G
c? 'd
0 0
CU
4J
cd
£ji
•rl
4-1
CO
4-1
CO
CO O
r-l O
O
rl T3
4J G
C cd
0
CJ i-l
o
cu i-i
4J 4-1
cd G
G O
r. 0
CU
4J 4-1
r-l G
-
G ^
i— 1 CO ^J
cd cu cd
4J M CU
•rl (-1 >-
cx cd -~~.
cd X! -co-
u o ^
c
o
•rl >—
4-1 i-l
cd cd
•r-l CU
0 >
CD ~s.
i-l •
d *v^
•r-l
CtJ v-
^
O 0
m m
00 CM
r-l
cd ^s
0 rl
•rl Cd
rl (U
4-1 >
o -~~-
cu
CU rl
OH _C3
O ^
O O
O O
CM CM
O
fa B
r. 0
•rl •— '
O O
O 0
O O
m m
CM
rl
CU
CU cu
4-1 0
0 -rl
CU >
i— 1 cu
CD Q
en
X> CU
3 G
rl O
CJ r-l
4-1 CO O
CU >
13 O
CU
G
j5
G
O
•rl
4J
cd
rl
CU
O
O
0
>> bl
U G
•r
i-l ^
CU P
O
m
in
A
00
*<}•
Ico
:-
r-l
00
CM
vfr
ft
CM
m
m
00
ft
~^f
0
o
r-l
ft
r-4
1 !-
i
i
I-l rl
Q O
CO
4J
CU
CU
a,
i-l
o
cd
CU
0
H-l
o
CO rl
C cd
O CU
CO rl
XI
o
>> o
4-1
-------
Total Annual
Control Costs Total Installed
($) Cost ($)
Case 1 - Best controls 12,570 54,800
Case 2 - Alternate controls 11,123 48,550
The material recovered by the control device is assumed to have no value,
and therefore, no credits result from the installation of the pollution
control device.
Financial Statement
The financial statements developed for the model alfalfa dehydrating
plant are for the processing plant only. Not included in the statements
are the harvesting, hauling, and product storage equipment and operations.
The financial statements were developed for the operation of the model
plant, both without and with pollution control equipment.
The principal sources of information used to develop the financial
statements were the USDA Economic Research Service Report MRR No. 881,—'
and the USDA Farmer Cooperative Service, FCS Information 68.12 /
A summary of the financial impact upon plant profitability shown in
Table 191 is as follows:
Pollution Control Equipment
Net Income Net Income
Without Controls With Controls Reduction
($/ton) ($/ton) ($/ton)
Case 1 - Best controls 6.40 4.91 1.49 23.3
Case 2 - Alternate con-
trols 6.40 5.08 1.32 20.7
Table 192 provides comparative balance sheet data. The affect of
pollution control equipment upon new plant construction costs is presented
below:
393
-------
PJ
s
o
M
H
<5
PS
p
w
p
,_]
w
g
H r>1
o^
Pi r-H
O -—•
H
53
M
H
H
U
M
.
'— (
T— 1
d)
i-H
,0
H
en
0
en r*
rH 4J
2 §
4J U
d
o -C
° .H
OJ &
4-J
CO
C
d)
4-)
rH
1^
CN 00
d o"
CO CO
CM OO
-^ CM
CN r-
E S S
O <-H \O
o o o
O
"--.
^| *t3
J (U
Ol Ot -rl
W S-i PL,
ey d)
X -M rH
O
•d" CO
CN *d"
CO
CO
d
0
CO
O
O
O
O
CO
rH CO vO CM
O m CN co
CM O i-H CO
o o o o
O"l OS \O rH
vO \O r-H
r-H i-H CO
vO
rH
d
o
m
CO
rH*
CO 00 vO CN
co in CN co
rH O rH CO
§OOO
O O O
m
^£ d>
O
H
OO
vO
CO
CN
CO
CM
CTi
CO
Cj\
CN
CO
rH
CO
CM
rH
i— 1
in
oo
CO
CM
o
CO
o"
o
CM
O
rH
O
m
CM
i-H
vO
CO
CM
CM
o
o
00
p^1
00
rH
en
d)
en
dJ
a.
X
bJ
nj
4J
O
H
CO
o
m
6-5 -S
r^ m oo
r- • •
CM
CM
CO
i-H
CO
CM
rH
rH
t-H
1
rH
^
O eN ^o
CO • •
CN O> <(•
i-H
O
i-H
o
in
CM
i-H.
1
O
vO*
0 0~ 0
O • •
OO CN vO
CO
m
en
4-1
en dl
d) .c en
X w en
cO i-i •<
H 0
S i-H
d) cfl
r-l -U 4-1
O d) O
MH S H
0) *--^ ^
PQ dJ OJ
d) O O
goo
0 C C
O M r-H
c
CD d)
d)
en
}_,
CO
d)
Ss
m
CM
U)
C
T)
•rt
jl
.n
en
^
co
at
r>.
o
CN
en
C
co
T3
C
cO
en
c
*rl
^i
en
5-4
CO
dl
>>
m
r-H
4-J •
d JJ
d) C J"J
d d) C
as a)
3 en 4-J
cr cj en
0) > ei)
C >
•H C
t3 rH
O C(J 4-» d>
.n -rl FJ DO
4-1 -U CD CO
E d w a* d
•rl en > to
d) d) co T3
£ 0 > -rl
•H 0 d *w X
r-l i-H -i-l i— 1 O
erj -r-l
X )-< cO i C!
60 d) -rH d) n)
•H CU *J £
nj -H o ^w
l-i O C3 O
4-J O -rH C
en O 4J
rH 5-2 W
.« oo cj
O <-<
•tH •> 1
4_) CJ r-H ....
co o 4J cu
•H C en >
o rd •• ei) -rl
d) M en ^4 4J
j-i 3 dJ CD -H
D- en X 4-» TD
0) d cO C T3
p M H M <
cO| ,O.| CJ j T>| QJ|
394
-------
(— i
k-3
PL
|
H
pi
O
^
w
^
fa
w
§ „
S CN
W 2
s
2:
C/i
W
K
^
M
CM
S
T^i
CO
H
CO
i— i
O
4-1
C
o
o
CU
4-J
C
CU
4J
<
1
CN
0)
CO
co
U
cn
0
4J
C
0
o
4-»
tn
0)
CQ
1
i— 1
CU
cn
n)
0
W]
0
4J
C
o
U
jq
•r-l
£5
C
0)
o
OJ
Pu
^D
m
CO
to
1— 1
1 — 1
Q
0
0
„
CO
cn
tn
4J
O cn1
CJ r-J
CO
0 «-i
V4 O
C ^-^
0
CO
0
4J
C
0
CJ
X
•H
4-J
S
O
a!
m
v£>
in
CO
CO
1— 1
o
Q
CO
4-1
cn x-x
CJ ^1
co
O rH
C ^~'
O
0
O
o
^
CO
LO
CO
r— 1
0
)-.
•y
0
4J
3
O
4J
-H
4J
fi
tU
CJ
rv|
PM
o
o
•o
CO
}-i
rH
Ǥ
o
o
1— t
CO
cn
m
CO
U
CU
cn
cn
4J
OJ
U U
0)
cn
OJ T3 (0 J2
" r—t *->
P- O
O
o
0
0
st
0
0
-------
Pollution Control Equipment
Plant Investment Plant Investment
Without Controls With Controls Increase
($/ton) ($/ton) ($/ton)
Case 1 - Best controls 36.80 43.40 6.60 17.9
Case 2 - Alternate con-
trols 36.80 42.60 5.80 15.8
Case 1 pollution control equipment increases the new plant construction
cost per ton 14% over Case 2 controls.
Economic Impact of Control Systems on Industry
New Plants - Table 193 presents a summary of the impact of pollution con-
trol equipment on the model plant. The capital investment for control equip-
ment increases the investment in a new plant by 18% in Case 1 and 167» in
Case 2. The annual operating costs for control equipment would reduce
profitability as measured by net income after taxes by 23% in Case 1 and
19% in Case 2. The installation of control equipment will have an impact
on new plants.
Existing Plants - The emission inventory questionnaires returned by in-
dividual alfalfa dehydrating plants indicated that none of the existing
plants are equipped with the wet scrubber system selected as the "best"
control equipment. Installation costs for existing plants will be some-
what higher than if the equipment were installed in a new plant. Cost also
will vary, depending upon the existing plant's size and configuration.
Table 194 summarizes the estimated economic impact of equipping ex-
isting plants with the control devices. Annual control costs are esti-
mated to be $1.69/ton (Case 1) and $1.50/ton (Case 2).
Demand Elasticity - Dehydrated alfalfa in meal or pellet form is used as
an ingredient in mixed feed for livestock and poultry. Since it is in
direct competition with a number of other major feed ingredients, the demand
for dehydrated alfalfa is sensitive to price changes. If all other in-
gredient prices remained unchanged or were changed less than dehydrated
alfalfa, the alfalfa dehydrating plants would have to absorb most of the
increased costs resulting from the installation of pollution control equip-
ment. If other types of plants--flour mills, soybean processing, feed
396
-------
Table 193. ECONOMIC IMPACT OF CONTROLS APPLIED TO NEW MODEL
ALFALFA DEHYDRATING PLANT
Control Investment
Percent of plant and equipment
Percent of dollar sales
Per ton of meal
Annual Control Operating Costs
Percent of net worth
Percent of total assets
Percent of dollar sales
Per ton of meal
Case 1
$54,800
17.7%
13.07o
$6.52
$12,570
2.8%
1.4%
3.0%
$1.50
Case 2
$48,550
15.7%
11.6%
$5.78
$11,980
2.7%
1.3%
2.8%
$1.43
397
-------
Table 194. CONTROLS APPLIED TO EXISTING ALFALFA DEHYDRATION PLANTS
Average Per Total for
Establishment Industry-'
Case 1
($)
Investment for
Control Equipment 42,640
Annual Control
Costs 9,217
Case 2 Case 1 Case 2
($) ($) ($)
37,780 12,792,000 11,333,000
8,157 2,765,000 2,447,000
Annual Control Costs
Per Ton of Meal 1.69 1.50
a/ Assumes 300 dehydrating plants with annual production, 1,634 thousand
tons.
398
-------
mills, etc.--which also supply feed ingredients were required to install
pollution control equipment, the incremental dehydrated alfalfa prices
would probably be passed on to the consumer.
Effect on Industry Structure - Regulations requiring the installation of
"best" pollution control equipment on new and existing facilities would
not have a significant impact on the economies of scale for alfalfa de-
hydrating plants. Since the cost of control equipment varies in relation
to the plant size, the smaller dehydrating plants will still be competitive
with larger plants. As a result, the installation of controls will not
significantly affect the industry structure. However, the installation of
controls will clearly have an affect on the industry. Some existing facili-
ties which are currently operated by small companies with marginal profits
may be forced to close.
WHEAT, RYE, AND DURUM MILLING
There is a great deal of similarity in the milling of wheat and rye.
As a result, a single model plant, processing wheat to regular flour, will
be used to assess the economics of pollution control for both of these
milling plants. This simplification results in some sacrifices in detail
for rye mills, but the assessment of total economic impact will not be af-
fected significantly. A separate model is used for the durum mill.
Description of Model Plant
The new model plant for the wheat mill equipped with the "best"
demonstrated control system is depicted in Figure 57. An alternate model
(Case 2) would substitute cyclones for fabric filters in the first three
phases of operation. The milling capacity of the plant is 5,000 cwt/24-
hr day. The mill is assumed to operate 6,000 hr/year for the production
of 1,250,000 cwt of flour. The milling operation of the plant is assumed
to be a pneumatic unit.
Control Equipment Costs
Control equipment and associated costs required for the new model
flour mill are summarized in Table 195 (Case 1) and Table 196 (Case 2).
Estimates are given for the investment cost of control devices for each
operation, as well as estimates for the total annual cost including elec-
trical charges, maintenance expenses, depreciation expenses and capital
charges.
399
-------
•8
O O
8. •
C "5 o 0)
oo •< co i—
^o
1-
_Q
O
O
S-l
4J
C
O
O
JJ
CO
QJ
^3
I
I
•i-l
g
O
i— I
M-l
CO
Q)
(1)
"8
a
M
400
-------
•s
c
8
O
O
o
fl
CO
H
fl O O CL CO
•H -P 4-1 (U *-»
C tfl (0 CO QJ
Q- fl tn O
0) 03 *HI U
9 c
-
00 &
e
4J 4J
U
CO CO CJ
00 O
U U O O
O O
CQ co O "
0) 0) * O
T3 T) m i— '
g
H
C
«
EC
401
-------
S
Pi
O
nj .u
u vi
C U
O
H
0
0^
o
E3
1
O
cT
J-i J-i S-l
O O D- ^1
4-1 4-1 01 J-4
CO -i-l O D
a a w 0
QJ « -H CJ
-w S
CO 01
CQ co cu a
bO
c:
o O O
o o
tn o -
aj - o
•O LO t-*
c 3 o
1-1 H PL,
C IJ
to a)
t-i a
a, o
402
| 0|T)|
-------
The operational hours per year which are shown for the model plant
were estimated from an analysis of (1) the operational requirements and
capacities of each device, and (2) the volume of material which could be
processed by each operation. Assumptions regarding electrical, maintenance,
depreciation and capital charges are discussed in the introduction to this
chapter.
Estimated total annualized cost and investment cost for Case 1 and
Case 2 are summarized as follows:
Primary Device
Case 1 - (Fabric filters)
Case 2 - (Cyclones)
Total
Annualized Cost
($/year)
98,730
79,610
Total
Installed Cost
($)
330,030
264,340
These figures actually overstate the costs associated with pollution con-
trol equipment. In the milling section of the plant, the fabric filter
system(s) function principally as product recovery systems and not as air
pollution equipment. Therefore, it is more in keeping with actual equip-
ment usage not to include the cost of this equipment as an air pollution
control item. Under this condition, the annual costs for pollution control
equipment are reduced 28% in Case 1 and 34% in Case 2; investment costs are
reduced 23% in Case 1 and 29% in Case 2.
Pollution Control Equipment Only
Case 1 - Best controls
Case 2 - Alternate con-
trols
Total Annualized
Cost ($/year)
71,400
52,280
Total Installed
Cost ($)
253,500
187,810
Credits for Dust Control
There are several control credits or positive impacts which could re-
sult from the installation of high-efficiency pollution control equipment
on flour mills.
403
-------
Since the equipment in the milling section is considered to function
for product recovery rather than for pollution control, the grain receiving,
transfer, storage, and cleaning house segments of the complex represent the
main area where credits would accrue. In the absence of reliable emission
factor data, only an indication of the potential positive impact from dust
control in the grain receiving, storage, and cleaning segments of the mill
can be provided. Table 197 presents an indication of the positive impact
for various assumed values of recovered dust and millfeed prices. In de-
veloping these data it was assumed that the recovered material entered the
millfeed stream and could be sold at a value of $45/ton which was the
average price the last half of 1972, and $90/ton, the average price during
the last half of 1973. The value of millfeed varies with time and market
conditions, and the positive impact will correspondingly change.
Financial Statements
Income statements and balance sheets for the model flour mill are
presented in Tables 198 and 199. Separate statements were developed for
the operation of the model plant both without and with pollution control
equipment. These statements reflect the costs of both the pollution con-
trol and product recovery equipment in the control equipment costs.
The primary information sources used in the development of these state-
ments were (1) financial data presented by Dr. Otto Eckstein in'Breadstuff
Seminar 1972 issue of The Southwestern Miller ;^9-' (2) National Commission
of Food Marketing, Organization and Competition in the Milling and Baking
Industries;—' and (3) 1970 Annual Survey of Manufacturers.il/ Since the
financial condition of the milling industry can vary signficantly by com-
pany and over time, the statements presented here can be considered as a
reflection of the general financial condition of a modern plant during
1971 and 1972.
The income statement of Table 198 is summarized for purposes of com-
parison as follows:
Pollution Control and Product Recovery Equipment
Net Income Net Income
Without Controls With Controls Reduction
(C/cwt) (c/cwt) (C/cwt) (%)
Case 1 - Best controls 33.6 25.7 7.9 23.5
Case 2 - Alternate con-
trols 33.6 27.2 6.4 19.1
404
-------
f— |
§
3
W
O
i
PM
o
nn
O
B
en
o
1 — 1
^
g
pa
o
M
M
w
1 — 1
O
g
o
o
o
o
e
p-l
s
>
E-t
M
o
Pu
•J
1— 1
H
H
g
(^
rH
Cti
H
4-)
CO
3
O
4-1
CS
O
U
rH
CO
3
C
5
M-l
O
c
QJ
CJ
Of
PH
CO
«
QJ
QJ
O
a
QJ
QJ
3
rti
>
CO
O
j-i
s
U
4-1
cu
B
QJ
4-1
rH
1
CNI
QJ
CO
8
1)
o
4-J
O
-tO-
rfl
"J
0
4-1
m
cti
CO
,_j
o
4-1
s
o
o
4-1
CO
OJ
FQ
t
rH
QJ
8
o
4-1
CO
3 Tt
(H QJ
m QJ
O >
0
QJ O
rH pej
cO
il
0
4-1
0
4-)
"cdl
J
o
4-1
in
5>
4J
fej
5
4J
0
1 I
Pd -v.
CJ 0
•H 4-»
CO ^-^
"
QJ
^ 'i
QJ 4-J _C3
> M
O 3 cj
0 P -H
QJ cd
Cd C M
•H Ofl
QJ M UH
BOO
3
en O o
rH
00 00
-a -a
QJ QJ
QJ QJ
"4H <4H
II
a]
405
-------
O C^
CM r-l
O (N O CM
hJ
\-\
2
3
En
,-J
W
Q
Q
o m m o
o oo co
O O i-l i-l
O CM O CM
o o o m
CN CM, CM T-J
H
H
0|
O'
o o
o m m o
o -d- vo en
CM i—I i-H i-H
I 8
CTJ -H T-l CO
CO JJ U CD
0) co nj
-------
,-J
ij
s
pi
B
3
[ri
O
a
pi
0
PM
H CM
W 1-
W c^
cn ^-*
W
u
z
5
<
CO
C^
O>
JJ
c
0)
rl
0)
0-i
s|
0
o
W
"-^
o
o
o
4J
c
in cr> cy\
I— i r-t CO rJ CO
IO O 3-
CO \O CO CN ^O iA
rH r-l
CN
cn -3- vo co o CM
CO CN CTv in CTv O
r-l i— 1 CO i— I St
!o o ,
CnFCrl3t^CUrlr-l
<3cooUricn3 jj 3 cn JJ c
JJ -H C ri U < O -H
C 01 CU (IJ 3 .C
0) CJ >J^I— trOrJO
CflrJtOCJJeCOlJJco
4J rlPS|-lO4J X^^
CU 3 O -H
cn O H fin
cn
r^
-------
If the control devices in the milling section are considered to be a
product recovery system rather than for pollution control, then the im-
pact of pollution control regulations on net income before taxes is as
follows:
Pollution Control Equipment Only
Net Income
Without Controls
(C/cwt)
Net Income
With Controls
(C/cwt)
Reduction
(C/cwt) (%)
Case 1 - Best controls 31.4 25.7 5.7 18.1
Case 2 - Alternate con-
trols 31.4 27.2 4.2 13.1
Even this latter case overstates the impact of pollution control equip-
ment on the model plant, because no credit has been given for the recovery
of dust from the grain receiving, transfer, storage, and cleaning operations,
The maximum credit of $18,750 as shown in Table 197 would result in even
less of a reduction in profitability as shown below:
Pollution Control Equipment Only
With Control Credits
Net Income Net Income
Without Controls With Controls Reduction
(C/cwt) (c/cwt) (C/cwt)
Case 1 - Best controls 31.4 27.2 4.2 13.4
Case 2 - Alternate con-
trols 31.4 28.5 2.9 9.2
Another facet that influences the actual impact on a milling complex
is the fact that some mills have multiple grain milling capability (e.g.,
wheat and rye, or wheat, dry corn and oats). In those cases, several pieces
of equipment, especially the grain receiving, cleaning and storage facili-
ties, are used for all the grains. Allocation of costs for pollution con-
trol equipment cannot be easily accomplished in these cases.
Table 199 presents the comparative balance sheets for the model plant.
A construction cost of $470 for each hundredweight of capacity per 24-hr
day was used to estimate the total plant and equipment cost without pollu-
tion control or product recovery equipment. According to industry sources,
408
-------
the construction costs for new flour mills can vary from $400 to $1,100/
cwt of capacity. This means that the figures as presented in the balance
sheet for the new model plant can vary accordingly. In general, the in-
stallation of control equipment will have a greater impact on the less ex-
pensive plants because the control equipment investment will be a greater
percentage of the total plant and equipment investment.
For the selected model plant, the addition of pollution control and
product recovery equipment increases the investment cost per hundredweight
in total plant and equipment as follows:
Pollution and Product Recovery Equipment
Investment Cost Investment Cost
Without Controls With Controls Increase
($/cwt) ($/cwt) ($/cwt) (7.)
Case 1 - Best controls 470 536 66 14
Case 2 - Alternate controls 470 523 53 11
If the product recovery equipment is included in the original investment
cost, then the construction costs will be as follows:
Pollution Control Equipment Only
Investment Cost Investment Cost
Without Controls With Controls Increase
($/cwt) ($/cwt) ($/cwt) (7.)
Case 1 - Best controls 485 536 51 10.5
Case 2 - Alternate con- 485 523 38 7.8
trols
Economic Impact of Control Systems on Industry
New Plants - The impact of pollution control equipment on the model flour
mill is summarized in Table 200. The annual operating costs of pollution
control and product recovery equipment amount to 1.17o of dollar sales at
1972 prices in Case 1, and 0.97o of sales in Case 2. If only pollution
control equipment is included, the increased cost is 0.87» of sales in Case
1 and 0.67o of sales in Case 2.
409
-------
Table 200. ECONOMIC IMPACT OF CONTROLS APPLIED
TO NEW MODEL FLOUR MILL
Pollution Control
and Product
Control investment
Percent of plant
and equipment
Percent of dollar
sales
Per cwt of flour
produced
Annual control
Operations costs
Percent of net
worth
Percent of total
assets
Percent of dollar
sales
Per cwt of flour
produced
Recovery
Case 1
$330,030
14.0%
3.7%
26.40
$ 98,734
4.1%
2.4%
1.1%
7.9c
Equipment
Case 2
$264,340
10.1%
3.0%
21.1c?
$ 79,614
3.3%
1.9%
0.9%
6.4<:
Pollution
Equipment
Case 1
$253,500
10.4%
2.8%
20.30
$ 71,400
3.0%
1.6%
0.80%
5.70
Control
Only
Case 2
$187,810
7.7%
2.1%
15.00
$ 52,280
2.2%
1.2%
0.59%
4.2o
410
-------
The annual costs of only the pollution control equipment for Case 1
and Case 2 are 3% and 2.2% of net worth, respectively. If profitability of
the plant is measured by net income before taxes per hundredweight of flour
production, the control equipment reduces the profitability 23.5% in Case 1
and 19.0% in Case 2.
Analyses of the financial data for the model plant indicate that re-
quired installation of "best" or "alternate" control equipment on new flour
mills will reduce profits. However, it is unlikely that control regula-
tions will prevent new plants with capacities of 5,000 cwt and greater from
being built. Because of the 20% greater investment and annual operating
costs, the installation of "best" controls in Case 1 will have a greater
impact than the installation of the alternate controls in Case 2.
Regulations requiring either of the specified control configurations
on all new plants will significantly change the economies of scale. Be-
cause of the relatively fixed costs of pollution control equipment for the
receiving, handling and loadout operations, the small flour mill will not
be as profitable.
Existing Plants - To determine the economic impact of installing the con-
trol systems on existing plants, it is necessary to take into account the
current level of control on these facilities. Table 201 presents the cur-
rent status of control at flour mills as determined from emission inventory
questionnaires submitted by 185 individual plants. Current plants are
well controlled in the handling and processing sections. However, only
approximately 15% are equipped with "best" control devices in the receiving
and handling sections, 35%, in the cleaning section, and 50% in the milling
section. If the controls in Case 2 are specified, then approximately 52%
of existing plants are equipped with adequate controls in receiving opera-
tions, 33% in handling, 100% in cleaning and 50% in milling.
Using the data in Table 201 as the industry average, the capital in-
vestment and annual costs required by existing plants to install and operate
the two alternative control systems were developed. The major assumptions
made in determining these costs are as follows:
1. The cost to install control equipment on an existing plant which
does not have pollution controls is 120% of the cost required for a new
plant. The increased costs reflect the fact that additional installation
charges will be incurred on an existing or older plant.
2. Existing plants which already have adequate control equipment on
specific operations will not incur any additional charges.
411
-------
CrO
H
<<
^
CM
cl
£2
1— I
y_4
X
w
0
.J
5
H
g
0
rt.
o
1— 1
g
1-3
Cu
1
O
M
M
"
ctf
o
fn
.
o
M
r4
5
H
CO
i-v.
ON
T— 1
CN
Os
i— 1
H
a
T
LT)
00
fo
0
SH
W
ft-
C/3
6-S
r- 1
cd
jj
o
H
M-l
o
CO •
V o
o z
•H
J>
M
CU
JJ
O
M-l
O
CO •
U 0
cu 2;
JJ
•H
u
•rl
U
cd
fa
M-l
O
•
O
a o o
•5 cu x p
cu o o C
0 33 PQ H
cu
a!
ON in CM
I*" vO 00
00 VO rH
O O CO
CM
O O OO
rH
CN| OV O
CM
ON oo
CM i-H O
r-4 CO
m •-* o
^•O
o r^-
LO -^ O
r^ Ov
O rH
0
0 O
OO 00
ov r*
r~- vo
m co
oo c~
in Ov
O i-I
rH CNI
CM CO
00 VO
rH rH
O 0
§0
0
t\ t\
m •>
ja
•d
0)
rH
o
jj
§
o
CO
•H
O
•H
r*,
Is
P!
O
•H
JJ
id
M
cu
PL.
o
CU
_r*1
JJ
rJ
O
M-l
r>V
JJ
•H
JJ
g
3
CT . rH
_, >> P
I— 1 rH r-l
Cd CJ JJ
JJ 0 C
0 0
JJ CO U
JJ
cu a M-I
43 cd 0
JJ rH
Q, JJ
M-l C
O T3 CU
CU JJ
CU rH X
60 rH CU
cd o
C JJ fi
CU (3 -H
0 o B
rJ U r-l
CU CU
0. P! JJ
O CU
CU T3
J2 T3
JJ CU O
CO JJ
co cd
-rl 42 Cd
rH CU Cd
O r-l T3
r-l Cd
JJ JJ
C CO C
o C
ft (U M
cd| ja| o
412
-------
3. The pollution control equipment specifications for the model plant
will be used as the average for the existing plants in the industry.
4. The maintenance and electrical expenses for a new fabric filter
system will be 50% and 80%, respectively, of the expense required for an
existing cyclone system.
A summary of the investment and annual operating costs required to
install controls or existing plants is presented in Table 202.
Table 202. CONTROLS APPLIED TO EXISTING FLOUR MILLS
Average Per Total for
Establishment Industry—'
Case 1 Case 2 Case 1 Case 2
Investment for control
equipment 232,000 125,000 75,000,000 40,471,000
Annual control costs 47,600 25,000 15,375,000 8,075,000
Annual costs per cwt of
flour production 6.1<: 3.2%
a/ Assumes 323 establishments.
For the total industry of 323 flour mills, the installation of best
controls would require, $75 million investment and $15.4 million annual
operating costs. The installation of controls specified in Case 2 would
reduce the total investment by 46% and the annual costs by 49%,.
As was the case with new plants, the impact of pollution control costs
on existing plants will be greater for small flour mills. It is possible
that some of the smaller or marginally profitable existing flour mills will
go out of business if forced to install control equipment. The enforcement
of pollution control regulations would accelerate the present trend in
which small and obsolete mills are being forced to close.
413
-------
Demand Elasticity - Per capita consumption of flour declined to 110 Ib
in 1971, from 118 Ib in 1960. This drop in per capita consumption has been
offset by an increase in population at an annual rate of 1.2%. As a result,
from 1963 through 1971, total domestic flour consumption increased at an
average annual rate of about 17o. The individual miller has little or no
control over the total domestic demand for flour. Since demand is rela-
tively flat and inelastic, the average price increase resulting from the
installation of control equipment would probably be passed on to the baker.
However, the family flour which is sold by the miller directly to retailers
has been subject to government price controls. In those cases where price
controls are in effect, the miller would have to absorb the increased produc-
tion costs.
Foreign demand which accounted for 7.6% of U.S. flour in 1972 to 1973,
has been sensitive to price changes during past years. The U.S. flour
milling industry has operated at a competitive disadvantage on the world
market because of the subsidy level on flour provided by the Common Market.
It is difficult to predict world demand for flour; however, under certain
conditions, the U.S. millers might have to absorb the control costs if they
are to maintain or increase flour exports.
Durum Flour Milling
Description of Model Plants - There is a great deal of similarity in the
milling of wheat and durum. As a result, some of the analyses which were
made for wheat flour milling also apply to durum flour milling. However,
there are enough differences to justify the development of a separate model
plant as depicted in Figure 58. The control devices specified represent
the best controls currently available. A similar model with alternative
controls, which replace fabric filters for cyclones in the first five opera-
tion phases, will also be analyzed. The milling capacity of the plant is
5,000 cwt/24-hr day, and the mill is assumed to operate 6,000 hr/year for
production of 1,250,000 cwt of semolina and durum flour. The milling por-
tion of the plant is assumed to be a pneumatic unit.
Control Equipment Costs - A summary of control equipment and associated
costs required for the model durum flour mill is presented in Table 203
(Case 1 - best control) and Table 204 (Case 2 - alternate controls).
Estimates are given for the investment cost for control devices for each
operation, as well as estimates for the total annual cost, including elec-
trical charges, maintenance expenses, depreciation expenses and capital
charges„
414
-------
X
-8
o o
§0
10
•5 8
D D
Q-U
.
U '
m
" *•
O) D
2 S
o Q.
(?) O
co
r-1
O
c
o
o
w
to
o>
O
r-4
4-1
oo
m
0)
M
•i-i
415
-------
o
M
M
Oi
O
OS
a
o
H
25
cO
a
1-H
eO
O !-<
V-i Q
4-1 ^H
U --^
cu -cn-
i-i
• co
C QJ
ex ^
o M
o
tu 2
M CJ
•H
QJ QJ
U -r4
CU >
.-H QJ
QJ O
C
O
•H
ctj
Q
P
C
o o o
*$• ir\ ir\
VD ^-i en
in" in oC
in co co
°1 °°B ^°-
^ r-.
oj oo r-
oo m vo
i-< m CN
»j- in m
v£> r-i en
en ^o in
o o o
en o o
oj m in
i— 1 OJ CN
o tn o
oo •-< oo
ro ^o CN
T-H OJ v£3
O o o
000
in m o
CN CN ^
O O O
moo
CN O O
oT in* in*
r-H OJ OJ
t-l
CU
en
^ P!
col CO
M ^ n
C 43| H
•H bO
> C TJ
•r4 -i-l P!
CJ T-I
QJ C1J &0
Prf U c4
1) -rH
J-i co ctj
H cj re
o
O
O
en
CN
en
0
in
o
0
en
CN
o
0
o
en
CT\
0
0
in
CN
o
o
0
o"
Pn
QJ
C!
CO
O
?
CO
(U
1— 1
cO
CJ
CO
000
in en cTi
m oo o
0*1 in CN
vo in r*
O tn M-4Cl)
CO-HCJ3 cO 4J -H B O
oocxexcoo cWM-i^iE •<-•
COJco-HU bOM-i-l3ca .u
•Hcrt
-
CM
CN
In
0
00
-
in
o
en
en
CN
r+
r~.
r-
r-T
T— 1
CD
4J
O
H
1 O J-4 J-l
OJ 3 r-t <-!
4J CM CO CO
Wl 01
O O O
u o o
o o
en A A
oi cu in o
3 3
Jl "01
416
-------
Q
3
&
O
fn
H
°A
o
\£S, 4-> U O
U -H -^
3 O ^ )-•
5 J3 XI
J-J CC TO
iw LH
M-I
O E E
4-4 M-4
I 4-» -W U O
tn
O O O
000
O O
417
-------
The major difference between the durum and wheat flour model plants
is the increased cubic feet per minute required for control equipment on
the cleaning house and milling operations of the durum mill. The durum
mill requires 60,000 cfm on the cleaning house and 100,000 cfm on the milling
section, as compared to 30,000 and 40,000, respectively, for the wheat flour
mill. The greater cubic feet per minute requirements result in higher costs.
For the pollution control equipment listed in Tables 203 and 204, the durum
flour mill would require estimated investments and annualized costs as
follows:
Pollution Control and Product
Recovery Equipment
Primary Device
Case 1 - Fabric filters
Case 2 - Cyclones
Total Annualized
Cost ($/year)
154,210
128,850
Installed
Cost ($)
458,030
371,340
In the milling section of the plant, the fabric filter systems func-
tion primarily as product recovery rather than pollution control systems.
If the costs associated with this equipment are removed from the control
costs, the investment cost for pollution control equipment would be reduced
34.6% in Case 1 and 42.7% in Case 2.
Primary Device
Case 1 - Fabric filters
Case 2 - Cyclones
Pollution Control Equipment Only
Annualized Installed
Cost ($/year) Cost ($)
89,250
63,900
299,660
212,970
Credits for Dust Control - The control credits which would result from
the installation of high-efficiency pollution control equipment on durum
flour mills is assumed to be the same as that shown in Table 197 for wheat
flour mills. The value of dust recovered, depending upon the emission
rates and millfeed prices, would range from $1,800 to $18,700. The $18,700
reflects fourth quarter 1973 prices. These credits are 1.2% and 12.2%,
respectively, of the total annual control costs.
418
-------
Financial Impact - According to the listings in the September 1971 issue of
the Northwestern Miller,22/ there are only 13 durum flour mills. Since
most of the companies operating these mills are integrated into other
sectors of the milling industry, there are almost no available statistics
on the financial operations of durum flour mills as distinguished from
other milling operations. As a result, the income statement and balance
sheet for the wheat flour mill—Tables 198 and 199--were used for the model
durum mill with the following changes.
1« The selling price of durum products are 5.6% higher than wheat
products, and the prices of ingredients required by the durum mill are 107o
higher. These price differentials were the same in the figures from the
1963 and 1967 Census of Manufacturers.
2. The investment required for plant and equipment was assumed to be
$500 for each hundredweight per 24 hr of capacity.
3. The wages and operating costs for the durum flour mill are lower
than for the wheat flour mill. The profitability at both mills was assumed
to be the same.
The resulting financial impacts of the installation of best controls
on the durum flour mill are summarized in Table 205. The annual costs of
pollution control and product recovery equipment in Case 1 amount to 12.3<:/
cwt, 10.3
-------
I-J
M
s
FLOUR
&
s
Q
w
Q
13
2
._-
H
O
w
^?
PM
CO
h-l
0
PS
H
§
o
H
U
i
M
M
S
O
o
W
LO
0
CM
W
i-l
*?
H
>
C
0
4-1
d
01
.5
3
cr
w
o
l-l
c
o
U
c
o
'"
4-1
3
rH
,— I
O
PM
CM
01
m O
to r-
C_3 JJT
CM
CM
•
4-J 0)
d o
8 |
d (5
o
•i-l 4-1
4J O
3 3
•-I -0
t-l o
0 M
P-i PM
*^"
ro
I 1
o
_i CO
^ 0
a 3
C_3 "^^
4J
d
OJ
6
4J
CO
01
^
d
M
, — 1
o
4J
d
0
0
&^-
o
00
5-2
CO
,_|
r-|
O
^
1 — 1
5-2
CO
oo
4-1
C
0)
CL
3
cr
w
*3
4J
d
OS
r— I
PM
m
0
4J
d
01
o
M
O)
p_i
5-5
CO
CM
CM
CO
O
^
c^
4-1
CO
O
O
M
OI
CL
O
, — i
0
4J
d
0
C_3
i — t
CO
3
C
C
CM
S
CO
O
LO
O
VO
4J
M
O
4J
OI
CM
O
4J
d
0)
o
0)
PM
6-S
CO
r-t
00
,— (
5^-
VD
CM
5-2
r— 1
CO
CO
4-J
01
CO
CO
•*
, — 1
CO
4-1
0
H
CH
o
4-1
d
01
U
M
0)
PM
5-2
00
O
LO
o
-------
DRY CORN MILLING
Description of Model Plants
Figure 59 depicts the model plant for the dry corn mill. The milling
capacity of the plant is 5,000 cwt/24-hr day, and the mill is assumed to
operate 6,000 hr/year. Grain storage capacity is assumed to be 500,000 bu.
Individual dry corn mills may vary significantly in processing steps,
operating characteristics, and product mix. In addition, the size of dry
corn mills covers a wide spectrum, and operations vary with size. Accurate
representation of the various corn mill sizes and configurations would re-
quire an extensive series of models. However, the model plant selected
should provide a basis from which alternative configurations could be readily
analyzed.
Control Equipment Costs
A summary of two alternative control equipment configurations and as-
sociated costs required for the model dry corn mill is presented in Tables
206 and 207. The control equipment in Case 1 which consists of fabric
filters for all-grain handling operations, is the "best" demonstrated con-
trol system currently available. Case 2, which specifies cyclones for the
grain-handling operations, generally reflects the current industry practice
for dry corn mills which have installed pollution control equipment. Esti-
mates are given for the investment cost of control devices for each opera-
tion, as well as estimates for the total annual cost. Assumptions regarding
electrical charges, maintenance expenses, depreciation and capital charges
are discussed in the introduction to this chapter.
A summary of the investment and annual operating costs required for
both pollution control equipment alternatives is as follows:
Annualized Installed
Primary Device Cost ($/year) Cost ($)
Case 1 - Fabric filters 117,820 430,260
Case 2 - Cyclones 99,790 373,970
As was the case with flour mills, the equipment in the milling sec-
tion of the plant functions primarily as product recovery systems and not
as air pollution control devices, and the costs for this equipment should
not really be attributed to pollution control.
421
-------
Basis:
Plant Capacity - 5,000 cwt/24 hr day
Storage Capacity - 500,000 bu
Operate - 6,000 hr/yr
\
FF
i
i
Trucks
FF
i
k
R.R.
Cars
Receiving
FF
t
Handling
Conveying
Bin Vents
etc.
i1
Scale &
Garner
Transfer
Self-
Cleaning
Screen
t
Drying
»-
Sc
M
Sc
St
F
i
re(
ill.
ou
on<
M
i
2ns
2 rotors
rers
2rs
Cleaning
House
Break Rolls
Sifters
Purifiers
Hammermills
Milling
Drying &
Sifting
FF - Fabric Filter
Figure 59. Model dry corn mill—best controls.
422
-------
CM •—t i-l
423
-------
4J O
, ••-! O
O O
424
-------
With this exclusion, the investment and annual costs for pollution control
are as follows:
Primary Device
Case 1 - Fabric filters
Case 2 - Cyclones
Pollution Control Equipment Only
Annualized Installed
Cost ($/year) Cost ($)
97,720
79,690
372,260
311,970
Credits for Dust Control
The dust recovered by high-efficiency equipment in the grain receiving,
storage, and cleaning operations can be added to the tnillfeed by-product
stream. Therefore, this material represents a positive impact resulting
from the use of pollution control equipment. Because accurate emission
factor data are lacking, only an estimate of the potential positive impact
can be made. Table 208 presents an indication of the positive impact for
various assumed levels of recovered dust. The recovered dust was assumed
to enter the millfeed stream and have a value of $40/ton which was the
average price for screenings during April 1973. The value of the recovered
material will fluctuate over time and the positive control credit will vary
accordingly.
Economic Impact of Control Systems on Industry
Financial Data - Most of the companies operating dry corn mills are integrated
into other sectors of the feed and grain industry. Also, dry corn milling
data collected by the Census of Manufacturers are included with flour and
other grain milling establishments. As a result, there are few available
statistics on the financial operations of dry corn mills as distinguished
from other milling operations. To determine the financial impact of the
best pollution control equipment on the model plant, the income statement
and balance sheet for the wheat flour mill—Tables 198 and 199--were used
with the following assumptions and changes.
1. The selling price of corn products is an average of 267o lower than
products from the wheat flour mill. This difference was derived from the
quantity and value of shipments by product classes as reported in the 1967
Census of Manufacturers.—'
2. The gross margin, operating expenses and net profit are the same
for both types of mills.
425
-------
ij
tJ
M
S
a
o
u
Q
W
Q
O
S
["4
O
o
M
B
U
c/1
2
M
e>
a
o
a
u
i_i
M
H
0
2
M
iJ
O
o
H
cn
Q
tn
0
H
O
M
U
H
M
cn
g
t •;
•<
H
M
H
S
CXI
o
CN
OJ
s
H
jj
cn
O
U
O
4-J
C!
3
ct)
3
C
C
M-l
0
4J
S
0)
o
n
CD
cn
ni
•O
0)
CD
o
0
CD
ca
CD
3
CD
O
V-i
4J
C
s
c
o
4-t
^
i-H
o
CM
4-1
U
3
O
PH
T3
c
CO
,— l
O
4J
C
O
U
c
o
*H
3
i— i
i— (
0
FM
cn
5
(£
O
>-
cu
o
u
cu
cu
£
cn
cn
>-,
pj
°
C
OJ
e
•H
D
cr
CN
o
u
OJ
pi
CN
CU
cn
to
5^ s~? 6-£ e^
o> oo vo in
rH cn m r^
r-*
CU
w
S~^ B~^ S~^ &-S
>X) CN QO
O
CU CJ
3 cu
rt
^D CN OO - -co- -cy> v>
cu
c
o o
CJ 4-1
OJ v^
oi
^
cu
-a 'Z-
P2 >n
S c
•H O
03 4-)
O ^
in cn O
CT^ P~^ ^D LT)
^D m o r^
(n
426
-------
3C The investment in plant and equipment without pollution control
equipment was assumed to be $500 for each hundredweight per 24 hr of
capacity.
The resulting financial impacts of installing best controls on the
model dry corn mill are summarized in Table 209. The investment costs for
pollution control and product recovery equipment amounts to 17.2% in Case
1 and 15.0%, in Case 2 of the original investment in plant and equipment.
If the product recovery equipment is excluded, the control investment cost
is reduced to 14.4% in Case 1 and 12.2% in Case 2. The annual costs of
pollution control and product recovery equipment are 2.1% of 1972 dollar
sales for Case 1 and 1.8% in Case 2.
New Plants - The investment required for installation of best control sys-
tems is great enough in comparison with the total plant construction cost
to be a major factor in determining the economic feasibility of a new dry
corn mill. In addition, the economics of scale for a new plant will change.
The costs of the control equipment for the grain receiving, handling and
transfer, scale and garner, and loadout operations will not decrease in
proportion to decreases in plant capacity. As a result, small dry corn
mills will become less economical.
The annual costs of pollution control systems will definitely be
greater than any direct economic benefits to the plants. However, it is
unlikely that the additional costs in either of the alternative control sys-
tems will have a great impact on new plants.
Existing Plants - The amount and type of pollution control equipment on
existing plants must be determined before an evaluation can be made of the
economic impact of regulations requiring best controls on existing plants.
Table 210 presents the current status of control equipment on dry corn mills
as determined from emission inventory questionnaires submitted by 39 of the
122 existing mills. Of the surveyed plants, approximately 60% have controls
on their receiving operations, 40% on handling operations, and 50% on milling
operations. However, only 157= of the surveyed plants are equipped with "best"
control devices.
Using the data in Table 210 as the industry average, the capital in-
vestment and annual costs required by existing plants to install and operate
the two alternative control systems were developed. The major assumptions
made in determining these costs are as follows:
427
-------
^
H
S
S
P^
o
0
£*-*
p3
p
,_J
w
p
Q
z
0
H
«
W
H
PH
PH
*^
CO
jj
O
CS1
H
O
O
[-T,
o
H
0
*3S
PH
^
M
O
1 — 1
y
0
E5
0
o
w
CT.
0
CM
w
1 —
<
H
CO
4-1
c
cu
o
K*~
I— 1
<§
4J
d
cu
@
•H
3
D-
W
,—1
0
M
4-1
C
O
U
d
o
•H
4-1
3
i— 1
i— 1
O
PH
CM ;>< n~-S
CN r^. o
co o CM in in
co r*^ i — i CM
C^ CTi
„
1— 1
I — 1
c/>
CO
4-1
d
0)
o
O f— i CM
i — 1 CM
n
cu co
cn vo
co co
O
CO
4J
d
cu
00°
O OO O
o m ^o o
\£> i — 1 CO
4-1
d
CU
*O -i-j
d 3
co a
w
, — i
0 >
4J CU
d >
0 0
O 0
cu
d P^
O
•i-l 4-1
4J O
3 3
t-l T3
i-l O
O M
PH PH
CN CM
.s
eu co
co r~~
n) co
c_5 -co-
co
4-1
0 0 0
d
M 4-1 4-1 4-1
d d g
^H CU
r— <
C7\
f^
f.
Q>
C^
0
CNI
OO
p^.
1
, — 1
-co-
co
4-1
in
O
O
.
i-i
cu
a.
O
r-4
0
4J
d
O
O
i— i
CO
3
d
d
"<3
g^2
CO
CO
g^O
,—1
(
^J-
&*2
CM
^j
5^2
O\
*
xj-
r{
4-1
^l
O
^2
5
CU
£5
<4-t
0
4-1
d
cu
o
>-i
cu
PH
>^o
fv.
^
g^O
I— (
.
CM
g^o
CN
CN
g^O
m
,
CM
CO
4-1
CU
CO
cn
-------
LO
E— '
E
O
S
H
c/i
X
u
p-l
o
01
J
o
H
"Z.
0
u
3
O
1— 1
H
IT)
,-J
g
P-4
O
2;
M
rJ
rJ
M
s
2;
od
0
u
IX
Pi
Q
O
CM
O
i — 1
cO
H
4-J
£ rH
QJ O
0 P
r-l 4J
QJ d
PL, O
o
CD -C
o ••-<
H S
OJ
O
>
0)
Q
r-i
QJ
X
4J
O
4-)
c
03
D-,
M-(
o
o
s
Cn O rH O F-^
<7^ C~«J !^ CO
in c^ li; r^-
o o o o o
0
M
4_t
c
0
u
f^
OD
1-1
QJ
r-l
[H
•i-4
^1
^ rQ
^ ffl
""- En
CTN
1
CM
«
4_)
c
ra
Oi
o
o
z,
in in
on
<
J
PL,
cr>
m QJ
C
PM o
O rH
a
>< >.
w 6
CO
w
4-J
c
CO
Pw
U-l
o
o
2;
r^ rH CM o
X>
rH m CM
! J_l rH
C CO
TO J-l
rH O
a H
j_j
c
0
•H
4-1
CO
1-1
OJ
&
o
W) C
C J-i 1-J QJ
-H 01 ffl ^ U
p> a, o o nj
0) O O I-i T3
u jr! cQ BH •<;
a>
prf
en
CM
en
CM
MD
GO
, — 1
^^
rQ|
o
o
in
rM
r^
en
0
o
o
o
o
0
-J-
1— 1
00
c
•H
Q
^ -^
T3| -Ol
i r^>c^r^rn i oinooo
r^ oo r- co imi-n1 — >
^H
co a\cor^r^ oo eMco^o
CM rH r-l rH
CN COrHOv£3 CN OOrHI^i e>i cMCMc>ien
O OOOO O OOOCM
o oooo o OOOCM
o oooo o ooom
e>i o\ -^ \o o m CM *j- 10 vO
r- o- i— j o CM LO -^" r**
o vovD^oo m in^^oo
T3
QJ
rH ,OQJ
rH CO rH QJ ^ O rW
O P2 O O O O P3
CJ
u
tu
T3
o
^
o
OJ
D.
cn
^
"^j
J^'
"O
GJ
'
c
i-t
4-1
c
O
u
w
H
,£:
O
•H
JZ
S
C
O
•H
03
VJ
QJ
D-.
o
^
4_)
•H
4J
d
CO
3
O4 • rH
^ 0
rH rH V-l
CO C -U
4-i o d
o o
4_i cn o
4-1
0) C M-l
.c to o
CX 4J
M-I d
O T3 QJ
QJ 4-1
01 rH X
OC • rH QJ
CO J-J O
-U -H ^i QJ
d c 4-1 d
Q) IZ> C -H
0 OB
r-l O O i-i
QJ CO QJ
a > d 4J
I O QJ
QJ >> T3
JS CO T3
-M O QJ O
cn 4-1
W •" CO
•H VJ ^3 CO
QJ 4-1
rH 4-> OJ CO
0 rH ^ T)
>H -H CO
4-1 *W 4-J
d cn C
O O OJ QJ
O -i-( 00 -H
(-< CO O
4J ,Q -P -i-t
d co c! m
Q) li-j CD U-J
O O 3
^ 4J V^ M
QJ O QJ d
— - ^ ^ *-.
cO| ^j O| T3
429
-------
1. The cost to install control equipment on an existing plant which
does not have pollution controls is 120% of the cost required for a new
plant. The increased costs reflect the fact that additional installation
charges will be incurred on an existing or older plant.
2. Existing plants which already have adequate control equipment on
specific operations will not incur any additional charges.
3. The pollution control equipment specifications for the model plant
will be used as the average for the existing plants in the industry.
4. The maintenance and electrical expenses for a new fabric filter
system will be 50% and 80%, respectively, of the expense required for an
existing cyclone system.
A summary of the investment and annual operating costs required to
install controls on existing plants is presented in Table 211.
Table 211. POLLUTION CONTROLS APPLIED TO EXISTING
DRY CORN MILLS
Average Per Establishement Total for Industry£/
Case 1 Case 2 Case 1 Case 2
(best controls) (alternate) (best controls) (alternate)
($) ($) ($) ($)
Investment for
controls 325,640 176,660 39,700,000 21,500,000
Annua1 c ontro1
costs 66,590 32,270 8,100,000 3,900,000
a./ Assumes 122 dry corn mills,
The installation of the alternate controls specified in Case 2 would
reduce the total industry investment required in Case 1 by 46% and the
annual control cost by 52%. This reduction results from (1) the lower
costs of the alternate control equipment, and (2) the increased number of
existing plants already equipped with control devices which satisfy the
requirements specified in Case 2.
430
-------
The application of controls to all existing dry corn mills will have
an impact on the industry. Some of the smaller or marginal plants will
probably be forced to close. The trend over the past 10 years toward
fewer mills with greater capacities would be increased if existing plants
were subject to best control regulations.
The increased costs resulting from pollution control will probably be
passed on to the consumer for industry products such as brewers grits and
corebinder. However, consumer products such as cornmeal or flour which are
sold directly to distributors may be subject to price controls. In these
cases, the plants may have to absorb the control costs.
RICE MILLING
Description of Model Plant
Figure 60 summarizes the characteristics of the model plant for rice
milling. The control devices shown are the "best" controls currently avail-
able. An alternative control system which substitutes cyclones for the
fabric filter in the grain handling operation also is analyzed. The mill
is assumed to be a rough rice mill only (i.e., no parboil). The capacity
of the model mill is 200 bu/hr, and the mill is assumed to operate 4,000 hr/
year. The mill is equipped with an optional grain dryer, in case rice is
not purchased from a commercial rice dryer. Financial figures,where appli-
cable, are expressed in hundredweights, using a conversion factor of 162 lb/
barrel.
Control Equipment Costs
A summary of the best control equipment (Case 1) and associated costs
required for the model plant is presented in Table 212. Similar figures
for an alternate control system are presented in Table 213 (Case 2). For
each operation, an estimate is given for the investment cost required for
the control devices, as well as estimates for the total annual costs.
The model rice mill will require investment costs and annual operating
costs as follows:
431
-------
Basis:
Plant Capacity - 200 barrels/hr
Operate - 4,000 hr/yr
Handling
Conveying
Bin Vents
Scale &
Garner
Transfer
Self-
Cleaning
Screen
Drying
(Optional)
Scalpers
Screens
Disc Sepr.
etc.
Cleaning
& Secondary
Dehulling
FF - Fabric Filter
Figure 60. Model new rice mill (no parboil)--best controls.
432
-------
^ rc ^
u y> a
a *j a
O (U C/3 QJ
PC CX Jj
^ U 3
00 (0 to O
cd u H o
•r-l C/l Q W
433
-------
—i ,-1 cr.
434
-------
Total Annualized Total Installed
Primary Device Cost ($/year) Cost ($)
Case 1 - (Fabric filter) 89,550 348,640
Case 2 - (Cyclones) 65,190 260,130
Credits for Dust Control
The dust and hulls recovered by the control equipment can be added to
the hull by-product stream. Material recovered represents a positive im-
pact if the hulls can be sold as an animal feed ingredient. As was the
case with other milling operations, emission factor data are meager for
rice milling operations and only an estimate can be made of the potential
positive impact. Table 214 presents such an estimate. The recovered dust
was assumed to enter the by-products stream and have a value of $30/ton.
Financial Statements
The income statements and balance sheets which were developed for the
model rice mill are presented in Tables 215 and 216. Separate statements
were prepared to show the operation of the model rice mill both without and
with pollution control equipment.
The principal information sources used in the development of these
statements were the 1970 Annual Survey of Manufacturers,!^/ the USDA Economic
Research Service Report on the Costs of Commercial Drying, Storing, and
Handling Rough Rice,^./ and the USDA Economic Service Report on the Cost of
Operating Southern Rice Mills.—'
As shown in Table 215, the net income before taxes is reduced by the
installation of pollution control equipment.
Pollution Control Equipment
Net Income Net Income
Without Controls With Controls Reduction
(c/cwt) (c/cwt) (C/cwt) (%)
Case 1 - Best controls 42.1 35.1 6.9 16.6
Case 2 - Alternate con-
trols 42.1 37.0 5.0 12.1
435
-------
Q
£5
<3
O
u-1
£>
M
W
O
§
£5
M
t "]
O
05
fn
^ . "i
0 nJ
CJ M
s
a
o w
M C_J
H H
t> Pi
iJ
0 W
PM P
O
O
H O
^J |^|
& o
1 — I EH
CJ
w w
p> en
H
H W
M O
w •<
o PS
PM O
H
(J CO
^_l
H
S3
r^
o
en
CU 4J
O cj C
cj Vi O
cu cu cj
Pi P |
i-H
4J CO Cd
co
Vi
[>
O
o
cu
td
a
P
j^
CO
a
CM
Q> ^->
co ?-2
cd ^^ *
o
LO O LO O
• • • •
i — 1 CO
CO &-2
cd -^
CJ
i-l CM rO CO
• • • •
i-l CM CO ^~
o
o ^
CU
PS
CM *-3" ^O 00
r-- <|- r-i oo
cy* o> cy\ oo
*\ « **
T-l CM CO
»rt
CU x-x
Vi ca
a) c
> 0
O 4J
CJ ^~-
OJ
,
fi "c
•H 0
Cd 4J
Vl ^^
o
o
0
00
A
•*
t
X-N
M-l *x3
O Q)
!— I
0 r^J
0 C!
4-1 Cd
^^* .^
o
r-l CU
s^- CJ
-I-l
^
i— 1 CM CO i
cu S
Vl
60
•U fd
-------
fj
,-;
M
s
Ed
CJ
M
ai
i-j
w
O
o
S
3
Ed
K
PS
0
fa
,^-v
H O
£5 I
fa" c^
W >-^-
S
H
cn
W
§
u
&
w
m
CN
i>
O OO vD CO O-i
o - -
•UM O CO OO
-W--J J— *
to
4J
CO
O
O
rH O
O O
J-l
4J V-
C
0
o
0]
i— i
2
jj
(3
O
u
.c
JJ
•r^
^3
JJ
c
co
O O^ CM CN
o r— co
1— 1
y^J O 1-1 I— 1 CM
Of co m i-* ^D
Ol CO vD CO CT>
0 - -
4J 1—
c
o
o
03
r-4
o
J-4
JJ
C
o
o
3
o
,-C
JJ
•H
S
JJ
c
0)
o
}-(
01
c^
O O> O> CO
O O> CN CM
o r-> co
1—4
^-*J O «-« i-H CM
ol co in i-i o
O CO ^O CO OX
0 " -
in co co
oo O
o o
i-l CM CO CM
terials
Wages
CO C
S o
• r-l
M-l 4J
0 0
3
4J T3
CO O
0 ^i
CJ CU
•0
T— 1
o
CO
CO
T3
O
o
o
CH
O
4J
CO
o
CJ
4J
•i-l
CW
O
u
p-<
w
CO
o
f-l
u
CO
cu
CO
£j
cu
a
X
Ed
tive Salaries
d Administration
CO C
H CO
4-1
CO 00
•H C
C -H
•H T-H
6 I— 1
•o cu
<3 co
Expenses
on
•H
00 4J
C co
•H •!-<
4J O
CO CU
IJ I-l
cu p
P CU
O P
4J
CO
01
^
cu
JJ
c
1-1
CO
-------
^
M
S
w
y
PS
i-j
Q
*2
a
pi
o
o
H !-•
W CT*
W i-l
ffi ^^
W
la
2
5
<
PQ
vO
t— 4
CM
cn
(U
PQ
1
rH
0)
CO
tti
t_3
4J
C
iH O (-»•
rH CD rH rH rH in rH
0 PH
t-l
4J
c
o
U
X , O CM o> >-i m
4J ,-J in o r-- ro ro
•HO rH CM MD O O
^0 « *
O rH rH CO rH
J
^H
(O
4J
CO
O
rH O
O O
5-1
G
o
4J
C O CO CM O rH
cn o o\ 0*1 rH o r*^
rH i~l rH rH rH IT) rH
o
G ^
o
U
4-1
G
M CU rH O CTi O rH
O M O co co
J-l O f-» CM v£> O O
•HO « "
J3 O>j rH rH CO rH
"—1
bo
•H
^o
rH
•H
3
-U PQ
CU
^ 4J T)
G G
CU r-l G
X r-l 3 H M
CO 0 U h 3
> 4J 3 4J
4J *H G r-l O CJ
G XIW
0) 3 O -H
cn U H Cn
en
<3
O CO
m CM
CM > ti
)-i CU
eu iQ
C
•H rH
CJ 4J
S H
C7\ CO
vJD CTi
O
m
CO P-
in
o
CM
O
O
o
rH
00
vD
O
^D
O-i
-.
cn
W 4J
cu C
•H 3
•u o
•H CJ
33
,£>
to
•H
rJ
•si- m
o r —
CM 00
m
CM
O-
CO
o
m
|