DA U.S. Environmental Protection Agency Industrial Environmental Research PA f^C\C\/7 7f\
Cr M Office of Research and Development Laboratory
Cincinnati. Ohio 45268 December 1976
ENVIRONMENTAL
CONSIDERATIONS OF
SELECTED ENERGY
CONSERVING MANUFACTURING
PROCESS OPTIONS:
Vol. XI. Glass Industry
Report
Interagency
Energy-Environment
Research and Development
Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S.
Environmental Protection Agency, have been grouped into seven series.
These seven broad categories were established to facilitate further
development and application of environmental technology. Elimination
of traditional grouping was consciously planned to foster technology
transfer and a maximum interface in related fields. The seven series
are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7- Interagency Energy-Environment Research and Development
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from
the effort funded under the 17-agency Federal Energy/Environment
Research and Development Program. These studies relate to EPA's
mission to protect the public health and welfare from adverse effects
of pollutants associated with energy systems. The goal of the Program
is to assure the rapid development of domestic energy supplies in an
environmentally—compatible manner by providing the necessary
environmental data and control technology. Investigations include
analyses of the transport of energy—related pollutants and their health
and ecological effects; assessments of, and development of, control
technologies for energy systems; and integrated assessments of a wide
range of energy-related environmental issues.
This document is available to the public through the National Technical
Information Service, Springfield, Virginia 22161.
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EPA-600/7-76-034k
December 1976
ENVIRONMENTAL CONSIDERATIONS OF SELECTED
ENERGY CONSERVING MANUFACTURING PROCESS OPTIONS
Volume XI
GLASS INDUSTRY REPORT
EPA Contract No. 68-03-2198
Project Officer
Herbert S. Skovronek
Industrial Pollution Control Division
Industrial Environmental Research Laboratory - Cincinnati
Edison, New Jersey 08817
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND .DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington. B.C. 30KB
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
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FOREWORD.
When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on our
health often require that new and increasingly more efficient pollution con-
trol methods be used. The Industrial Environmental Research Laboratory -
Cincinnati (lERL-Ci) assists in developing and demonstrating new and im-
proved methodologies that will meet these needs both efficiently and
economically.
This study, consisting of 15 reports, identifies promising industrial
processes and practices in 13 energy-intensive industries which, if imple-
mented over the coming 10 to 15 years, could result in more effective uti-
lization of energy resources. The study was carried out to assess the po-
tential environmental/energy impacts of such changes and the adequacy of
existing control technology in order to identify potential conflicts with
environmental regulations and to alert the Agency to areas where its activi-
ties and policies could influence the future choice of alternatives. The
results will be used by the EPA's Office of Research and Development to de-
fine those areas where existing pollution control technology suffices, where
current and anticipated programs adequately address the areas identified by
the contractor, and where selected program reorientation seems necessary.
Specific data will also be of considerable value to individual researchers
as industry background and in decision-making concerning project selection
and direction. The Power Technology and Conservation Branch of the Energy
Systems-Environmental Control Division should be contacted for additional
information on the program.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
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EXECUTIVE SUMMARY
In a ranking of the energy intensive industries in the United States
(see Table ES-1), the glass manufacturing industry is one of the most signif-
icant with a ranking of 9 out of 13. Based on technology, product markets
and energy consumption, the glass manufacturing industry is viewed as con-
sisting of four major segments: flat glass, ^66 x 1012, Btu, container glass,
M.55 x 1012 Btu, pressed and blown glass, ^67 x 1012 Btu, and glass fiber,
^53 x 1012 Btu. In total the 1972 industry shipments were valued at over
$4 billion from approximately 400 plants in the United States.
Of the six forms of energy used in the glass industry, natural gas
represents by far the major form (70%). In recent years relative fuel oil
consumption has increased 0*4% in 1971 to 9% in 1972) since fuel oil is a
viable alternative to natural gas for melting glass, and the percent of
natural gas declined (75% in 1971 down to 70% in 1972) reflecting the supply
problem facing the industry. Improvement in energy conservation in the
industry can be expected from the introduction of newer industrial practices
or processes because of shortages or risk of shortage of natural gas, the
primary fuel form in this industry. The use of process modifications and
changes in fuel form could result in new or additional pollution loads and
therefore require new or additional pollution control techniques.
This study of possible process modifications or the use of alternative
fuel forms in the glass industry focused on the unit process of melting since
it is in the glass melting function that 60-80% of the total energy for glass
manufacturing is consumed, and it is this area that comes closest to being
the same for all segments of the industry. Alternative fuel forms for melt-
ing analyzed in this study included coal gasification, direct coal firing,
coal hot gas generation, and electric melting. The use of oxygen enrichment
and submerged burners were briefly considered. Further, a major process
modification, that of batch agglomeration and preheating, was also analyzed.
In our analysis, technical feasibility, capital investment cost, operating
cost, pollution loads, and the cost of pollution control were the key factors
considered in comparing the alternative fuel forms and process modifications
with, present melting practices using natural gas in a 200 tpd side-port fired,
regenerative furnace melting a soda-lime-silica type glass.
In terms of total energy consumed in the melting process, the use of all
of the alternative fuel forms investigated requires higher energy input per
ton of glass produced and thus is not energy conserving. However, all
involve the use of coal, a less critical fuel. Primarily because the alter-
native fuel forms of coal gasification, coal hot gas generation, arid direct
iv
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TABLE ES-1
SUMMARY OF 1971 ENERGY PURCHASED IN SELECTED INDUSTRY SECTOR
Industry Sector
1. Blast furnaces and steel mills
2. Petroleum refining
3. Paper and allied products
4. Olefins
5. Ammonia
6. Aluminum
Textiles
Cement
Glass
7
8
9
10
11
Alkalies and chlorine
Phosphorus and phosphoric
acid production
12. Primary copper
13. Fertilizers (excluding ammonia)
1015 Btu/Yr
3.49
2.96
1.59
0.63
0.59
0.54
0.52
0.31
0.24
(1)'
(2)
(4)
0.12
0.081
0.078
(5)
SIC Code
In Which
Industry Found
3312
2911
26
2818
287
3334
22
3241
3211, 3221, 3229
2812
2819
3331
287
(1)
(2)
'(3)
(4)
(5)
Estimate for 1967 reported by FEA Project Independence Blueprint, p. 6-2,
USGPO, November 1974,
Includes captive consumption of energy from process byproducts (FEA Project
Independence Blueprint)
Olefins only, includes energy of feedstocks: ADL estimates
Ammonia feedstock energy included: ADL estimates
ADL estimates
Source: 1972 Census of Manufactures, FEA Project Independence Blueprint,
' USGPO, November 1974, and ADL estimates.
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firing with pulverized coal all involve higher volumes of gas, the emissions
from the glass tank, principally SOX and particulates, are increased over
those from furnaces using natural gas. Consequently the cost of pollution
control is estimated to be substantially greater with the use of these alter-
native fuel forms. The capital cost involved for additional facilities to
produce and convert the fuel form and the pollution control indicates that
coal gasification and coal hot gas generation may not be economically viable
alternatives to the use of natural gas. The use of direct fired coal proc-
esses, in addition to somewhat higher capital and operating costs, presents
formidable technical problems in terms of glass quality and furnace life.
Electric melting of glass appears to be a viable process from both a
technical and economical standpoint. Although the total energy consumed is
higher than for natural gas melting (by 12%), when consideration is given to
the efficiencies of generation, transmission and distribution of the electric
power, and to the energy used in pollution control, a less critical form of
energy is utilized. Air emission loads can be considerably lower than for
natural gas melting on any of the other coal related fuel forms analyzed.
Utilization of waste heat to preheat the batch prior to introduction
into the melting furnace has the potential of reducing the energy consumption
of the melting function by approximately 20%. Because of the lower fuel
requirement in the melting process the emissions from the furnace and cost
of control are reduced. Batch preheating could be used with any of the alter-
native fuel forms and with effective demonstration of the feasibility of such
a system could find broad application in the industry.
Effective air emission control systems for glass melting furnaces have
not been established. Regardless of which fuel form is used in the industry
some form of effective control will probably be required in the future. Water
and solid waste streams are of less significance and few additional streams
are introduced in any of the alternative fuel forms or process modifications
studied.
This report was submitted in partial fulfillment of contract 68-03-2198
by Arthur D. Little, Inc. under sponsorship of the U.S. Environmental Protec-
tion Agency. This report covers a period from June 9, 1975 to January 23, 1976,
vi
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TABLE OF CONTENTS
FOREWORD
EXECUTIVE SUMMARY iv
List of Figures x
List of Tables xi
Acknowledgments xiii
Conversion Table xv
I. INTRODUCTION 1
A. BACKGROUND 1
B. CRITERIA FOR INDUSTRY SELECTION 1
C. CRITERIA FOR PROCESS SELECTION 3
D. SELECTION OF GLASS INDUSTRY PROCESS OPTIONS 3
II. FINDINGS AND CONCLUSIONS 6
A. FINDINGS 6
B. CONCLUSIONS 11
C. IMPACT OF EPA POLICIES ON FUTURE CHOICE OF ALTERNATIVES 12
D. PRACTICES/PROCESSES REQUIRING ADDITIONAL RESEARCH 12
III. INDUSTRY OVERVIEW 13
IV. COMPARISON OF CURRENT AND ALTERNATIVE PROCESSES 15
A. INTRODUCTION 15
I'. Process, Options Analyzed 15
2. Basis of Production Cost Analysis 16
B. CURRENT PROCESS (BASE CASE) 17
1. Process Description 17
2. Energy Considerations 19
3. Economic Considerations 22
4. Environmental Considerations 26
C. COAL GASIFICATION 32
1. Process Description 32
2. Energy Considerations 34
3. Economic Considerations 36
4. Environmental Considerations 38
D. DIRECT COAL FIRING 45
1. Process Description 45
2. Energy Considerations 45
3. Economic Considerations 46
4. ' Environmental Considerations 46
vii
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TABLE OF CONTENTS (Cont.)
Page
E. COAL-FIRED HOT GAS GENERATION 48
1. Process Description 48
2. Energy Considerations 49
3. Economic Considerations 51
4. Environmental Considerations 53
F. ALL ELECTRIC MELTING 53
1. Process Description 53
2. Energy Considerations 55
3. Economic Considerations 55
4. Environmental Considerations 57
G. BATCH AGGLOMERATION - PREHEATING 58
1. Process Description 58
2. Energy Considerations 60
3. Economic Considerations 60
4. Environmental Considerations 62
V. IMPLICATIONS OF POTENTIAL PROCESS CHANGES 63
A. COAL GASIFICATION 63
1. Impact On Pollution Control/Energy Requirements 63
2. Factors Affecting Probability of Change 65
3. Areas of Research 65
B. DIRECT COAL FIRING 65
1. Impact On Pollution Control/Energy Requirements 65
2. Factors Affecting Probability of Change 66
3. Areas of Research 66
C. COAL-FIRED HOT GAS GENERATION 66
1. Impact On Pollution Control/Energy Requirements 66
2. Factors Affecting Probability of Change 67
3. Areas of Research 67
D. ELECTRIC MELTING 68
1. Impact On Pollution Control/Energy Requirements 68
2. Factors Affecting Probability of Change 68
3. Areas of Research 69
E. BATCH PREHEATING 69
1. Impact On Pollution Control/Energy Requirements 69
2. Factors Affecting the Probability of Change 69
viii
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TABLE OF CONTENTS (Cont.)
Page
APPENDIX A - INDUSTRY STRUCTURE - GLASS MANUFACTURING 71
APPENDIX B - ENERGY USE: BASE LINE PROFILE 96
APPENDIX C - PROCESSES CONSIDERED 101
APPENDIX D - BIBLIOGRAPHY 108
ix
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LIST OF FIGURES
Number Page
IV-1 Typical Side Port Regenerative Furnace 20
IV-2 Fuel Savings Due to Regeneration 21
IV-3 Log-Probability Distribution of Particle Sizes 28
IV-4 Performance Comparison for Particulate Control Systems 29
IV-5 Air Pollution Control System for Glass Melting Furnace 31
IV-6 Wellman Two-Stage Gas Process 35
IV-7 Flow Chart for Industrial COHOGG 50
IV-8 General Schematic of Batch Agglomeration - Preheating 59
A-l Glass Manufacture 83
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LIST OF TABLES
Number Page
1-1 Summary of 1971 Energy Purchased in Selected Industry Sectors 2
II-l Summary of Energy Consumption, Glass Melting Unit Process 7
II-2 Summary of Investment and Operating Cost for the Base Case and
Alternative Melting Unit Fuel Processes and Process
Modifications 8
II-3 Air, Water, and Solid Waste Streams from Base Case and
Alternative Fuel Systems and Process Modifications 9
II-4 Qualitative Comparison of the Alternative Process Economics,
Energy, and Environmental Implications 10
IV-1 Operating Assumptions for Base Case 18
IV-2 Production Cost Estimate: Natural Gas-Fired, Side Port,
' Regenerative Furnace - Base Case 23
IV-3 Breakdown of Raw Material Weights and Costs 24
IV-4 Typical Commercial Glass Batch Minor Additives 25
IV-5 Glass Melting Furnace Emissions 27
IV-6 Air Pollution Control Costs 31
IV-7 Wastewater Treatment Cost: Glass Melting Via Natural Gas-
Fired Furnace - Base Case 33
IV-8 Production Cost Estimate: Coal Gasification 37
IV-9 Sulfur Control Costs for Coal Gasifier 39
IV-10 Stack Gas Flow Rates 40
IV-11 Air Pollution Control Costs for Glass Melting Furnace 41
IV-12 Utility Requirements for Air Pollution Control 42
IV-13 ' Water Pollution Control Costs for Glass Melting Furnace 44
IV-14 Production Cost Estimate: Direct Coal Firing 47
xi
*
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LIST OF TABLES (Cont.)
Number Page
IV-15 Production Cost Estimate: Coal-Fired Hot Gas Generation 52
IV-16 Production Cost Estimate: All-Electric Melting 56
IV-17 Production Cost Estimate: Natural Gas-Fired; Batch
Agglomeration-Preheating, Side Port, Re'generative Furnace 61
V-l Summary of Investment and Operating Cost for the Base Case and
Alternative Fuel System and Process Modifications 64
A-l Flat Glass Companies by Type of Plant and Location 73
A-2 Glass Container Manufacturers 75
A-3 Major Glass Tubing Manufacturers 76
A-4 Typical Plant Characteristics 78
A-5 Fiber Glass Plants by Company and Location 80
A-6 Composition of Commercial Glasses by Weight Percent 81
A-7 Shipments of Flat Glass, 1968 - 1972 84
A-8 U..S. Shipments and Value of Wool Glass Fiber, 1964 - 1971 86
A-9 U.S. Shipments and Value of Textile Glass Fiber, 1964 - 1971 87
A-10 Shipments, Exports, Imports, Apparent Consumption: Machine
Made Consumer Glasswares, 1969 - 1972 89
A-ll Shipments of Glass Tubing, 1964 - 1974 90
A-12 Shipments, Imports, Exports and Apparent Consumption: Glass
Containers, 1969 - 1972 91
A-13 Domestic Shipments of Glass Containers, 1972 92
A-14 Glass Container Shipments by Type, 1967 - 1972 93
B-l Percent of Total Plant Energy Consumption by Industry
Segment and Process Step 97
B-2 Relative Use of Different Energy Forms, 1973 99
C-l Summary of Several Process Modifications Considered for the
Melting Process 106
.xii
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ACKNOWLEDGMENTS
This study could not have been accomplished without the support of a
great number of people in government agencies, industry, trade associations
and universities. Although it would be impossible to mention each individual
by name, we would like to take this opportunity to acknowledge the particular
support of a few such people.
Dr. Herbert S. Skovronek, Project Officer, was a valuable resource to us
throughout the study. He not only supplied us with information on work
presently being done in other branches of EPA and other government agencies,
but served as an indefatigable guide and critic as the study progressed. His
advisors within EPA, FEA, DOC, and NBS also provided us with insights and
perspectives valuable for the shaping of the study.
During the course of the study we also had occasion to contact many
individuals within industry and trade associations. Where appropriate we
have made reference to these contacts within the various reports. Frequently,
however, because of the study's emphasis on future developments with compara-
tive assessments of new technology, information given to us was of a confiden-
tial nature or was supplied to us with the understanding that it was not to be
credited. Therefore, we extend a general thanks to all those whose comments
were valuable to us for their interest in and contribution to this study.
Finally, because of the broad range of industries covered in this study,
we are indebted to many people within Arthur D. Little, Inc. for their parti-
cipation. Responsible for the guidance and completion of the overall study were
Mr. Henry E. Haley, Project Manager; Dr. Charles L. Kusik, Technical Director;
Mr. James I. Stevens, Environmental Coordinator; and Ms. Anne B. Littlefield,
Administrative Coordinator.
Members of the environmental team were Dr. Indrakumar L. Jashnani,
Mr. Edmund H. Dohnert and Dr. Richard Stephens (consultant).
Within the individual industry st.udies we would like to acknowledge the
contributions of the following people.
Iron and Steel; Dr. Michel R. Mounier, Principal Investigator
Dr. Krishna Parameswaran
Petroleum Refining; Mr. R. Peter Stickles, Principal Investigator
Mr. Edward Interess
Mr. Stephen -A. Reber
Dr. James Kittrell (consultant)
Dr. Leigh Short (consultant)
xiii
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Pulp and Paper:
Olefins:
Ammonia:
Aluminum:
Textiles:
Cement:
Glass:
Chlor-Alkali:
Phosphorus/
Phosphoric Acid;
Primary Copper:
Fertilizers:
Mr. Fred D. lannazzi, Principal Investigator
Mr. Donald B. Sparrow
Mr. Edward Myskowski (consultant)
Mr. Karl P. Fagans
Mr. G. E. Wong
Mr. Stanley E. Dale, Principal Investigator
Mr. R. Peter Stickles
Mr. J. Kevin O'Neill
Mr. George B. Hegeman
Mr. John L. Sherff, Principal Investigator
Ms. Nancy J. Cunningham
Mr. Harry W. Lambe
Mr. Richard W. Hyde, Principal Investigator
Ms. Anne B. Littlefield
Dr. Charles L. Kusik
Mr, Edward L. Pepper
Mr. Edwin L. Field
Mr* John W. Rafferty
Dr. Douglas Shooter, Principal Investigator
Mr, Robert M. Green (consultant)
Mr, Edward S% Shanley
Dr, John Willard (consultant)
Dr, Richard F, Heitmiller
Dr, Paul A. Huska, Principal Investigator
Ms. Anne B. Littlefield
Mr.. J.. Kevin O'Neill
Dr. D. William Lee, Principal Investigator
Mr, Michael Rossetti
Mr, R, Peter Stickles
Mr, Edward Interess
Dr, Ravindra M. Nadkarni
Mr. Roger E. Shamel, Principal Investigator
Mr, Harry W. Lambe
Mrs Richard P. Schneider
Mr. William V. Keary, Principal Investigator
Mr. Harry W. Lambe
Mr. George C. Sweeney
Dr, Krishna Parameswaran
Dr. Ravindra M. Nadkarni, Principal Investigator
Dr, Michel R. Mounier
Dr, Krishna Parameswaran
Mr. John L. Sherff, Principal Investigator
Mr. Roger Shamel
Dr. Indrakumar L. Jashnani
xiv
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ENGLISH-METRIC (SI)' CONVERSION FACTORS
To Convert From
To
Metre2
Pascal
Metre3
.t Joule
Pascal-second
Degree Celsius
Degree Kelvin
Metre
Metre /sec
Metre3
Metre2
Metre/sec
2
Metre /sec
I) Metre3
-Ibf/sec) Watt
Lc) Watt
1 Watt
Metre
Joule
Metre3
Metre
Metre
) Metre
Pascal-second
Newton
Kilogram
1 Kilogram
Kilogram
Kilogram
Kilogram
Kilogram
Multiply By
4,046
101,325
0.1589
1,055
0.001
t° = (t' -32)
c F
0.3048
0.0004719
0.02831
0.09290
0.3048
0.00002580
0.003785
745.7
746.0
735.5
0.02540
3.60 x 106
1.000 x 10~3
1.000 x 10~6
0.00002540
1,609
0.1000
4.448
0.4536
0.02916
1,016
1,000
907.1
1,000
Acre
Atmosphere (normal)
Barrel (42 gal)
British Thermal Unit
Centipoise
Degree Fahrenheit
Degree Rankine
Foot
Foot /minute
Foot3
2
Foot
Foot/sec
2
Foot /hr
Gallon (U.S. liquid)
Horsepower (550 ft-1
Horsepower (electric)
Horsepower (metric)
Inch
Kilowatt-hour
Litre
Micron
Mil
Mile (U.S. statute)
Poise
Pound force (avdp)
Pound mass (avdp)
Ton (assay)
Ton (long)
Ton (metric)
Ton (short)
Tonne
Source: American National Standards Institute, "Standard Metric Practice
Guide," March 15, 1973. (ANS72101-1973) (ASTM Designation E380-72)
xv
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I. INTRODUCTION
A. BACKGROUND
Industry in the United States purchases about 27 quads* annually, approx-
imately 40% of total national energy usage.** This energy is.used for chemical
processing, raising steam, drying, space cooling and heating, process stream
heating, and miscellaneous other purposes.
In many industrial sectors energy consumption can be reduced significantly
by better "housekeeping" (i.e., shutting off standby furnaces, better thermo-
stat control, elimination of steam and heat leaks, etc.) and greater emphasis
on optimization of energy usage. In addition, however, industry can be expected
to introduce new industrial practices or processes either to conserve energy
or to take advantage of a more readily available or less costly fuel. Such
changes in industrial practices may result in changes in air, water or solid
waste discharges. The EPA is interested in identifying the pollution loads of
such new energy-conserving industrial practices or processes and in determin-
ing where additional research, development, or demonstration is needed to
characterize and control the effluent streams.
B. CRITERIA FOR INDUSTRY SELECTION
In the first phase of this study we identified industry sectors that have
a potential for change, emphasizing those changes which have an environmental/
energy impact.
Industries were eliminated from further consideration within this assign-
ment if the only changes that could be envisioned were:
• energy conservation as a result of better policing or "housekeeping,"
• better waste heat utilization,
• fuel switching in steam raising, or
• power generation.
After discussions with the EPA Project Officer and his advisors, industry
sectors were selected for further consideration and ranked using:
*1 quad = IQiS Btu
**Purchased electricity valued at an approximate fossil fuel equivalence of
10,500 Btu/kWh.
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• Quantitative criteria based on the gross amount of energy (fossil
fuel and electric) purchased by industry sector as found in U.S.
Census figures and on information provided from industry sources. The
glass industry purchased 0.31 quads out of the 12.14 quads purchased
by the 13 industries selected for study in 1971, or 1% of the 27 quads
purchased by all industry (see Table 1-1). Of this 0.31 quads 74% is
in the most critical form, natural gas.
• Qualitative criteria relating to probability and potential for pro-
cess change, and the energy and effluent consequences of such changes.
In order to allow for as broad a coverage of technologies as possible, we
then reviewed the ranking, eliminating some industries in which the process
changes to be studied were similar to those in another industry planned for
study. We believe the final ranking resulting from these considerations iden-
tifies those industry sectors which show the greatest possibility of energy
conservation via process change. Further details on this selection process
can be found in the Industry Priority Report prepared under this contract
(Volume II). On the basis of this ranking method, the glass industry appeared
in eighth place among the 13 industrial sectors listed.
TABLE 1-1
SUMMARY OF 1971 ENERGY PURCHASED IN SELECTED INDUSTRY SECTORS
SIC Code
jc ' In Whlcli
Industry Sector 10 Btu/Yr. Industry Found
1. Blast furnaces and steel mills 3.49'1' 3312
2. Petroleum refining . 2.96^2) 2911
3. Paper and allied products 1.S9 26
4. Oleflns 0.9B4(3) 2818
5. Ammonia 0.63^ 287
6. Aluminum 0.59 3331
7. Textiles 0.54 22
8. Cement 0.52 3241
9. Class 0.31 3211, 3221, 3229
10. Alkalies and chlorine 0.24 2812
11. Phosphorus and phosphoric ,,.\
acid production 0.12 2819
12. Primary copper 0.081 3331
13. Fertilizers (excluding ammonia) 0.078 287
'Estimate Cor 1967 reported by FEA Project Independence Blueprint,
p. 6-2, USCPO, November 1974.
Includes captive consumption of energy from process byproducts
(FEA Project Independence Blueprint)
Olefins only, includes energy of feedstocks: ADL estimates
(4) •
Amonla feedstock energy included: ADL estimates
^'M)L estimates
Source: 1972 Census of Manufactures, FEA Project Independence Blueprint,
USCPO, November 1974, and ADL estimates.
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C. CRITERIA FOR PROCESS SELECTION
In this study we have focused on identifying changes in the primary pro-
duction processes which have clearly defined pollution consequences. In select-
ing those to be included in this study, we have considered the needs and limita-
tions of the EPA as discussed more completely in the Industry Priority Report
mentioned above. Specifically, energy conservation has been defined broadly
to include, in addition to process changes, conservation of energy or energy
form (gas, oil, coal) by a process or feedstock change. Natural gas has been
considered as having the highest energy form value followed in descending
order by oil, electric power, and coal. Thus, a switch from gas to electric
power would be considered energy conservation because electric power could be
generated from coal, existing in abundant reserves in the United States in
comparison to natural gas. Moreover, pollution control methods resulting in
energy conservation have been included within the scope of this study. Finally,
emphasis has been placed on process changes with near-term rather than long-
term potential within the 15-year span of time of this study.
In addition to excluding from consideration better was-te heat utilization,
"housekeeping," power generation, and fuel switching, as mentioned above, cer-
tain options have been excluded to avoid duplicating work being funded under
other contracts and to focus this study more strictly on "process changes."
Consequently, the following have also not been considered to be within the
scope of work:
• Carbon monoxide boilers (however, unique process vent streams yield-
ing recoverable energy could be mentioned);
• Fuel substitution in fired process heaters;
• Mining and milling, agriculture, and animal husbandry;
• Substitution of scrap (such as reclaimed textiles-, iron, aluminum,
glass, and paper) for virgin materials;
• Production of synthetic fuels from coal (low- and high-Btu gas,
synthetic crude, synthetic fuel oil, etc.); and
• All aspects of industry-related transportation (such as transporta-
tion of raw material).
D. SELECTION OF GLASS INDUSTRY PROCESS OPTIONS
Within each industry, the magnitude of energy use was an important crite-
rion in 'judging where the most significant energy savings might be realized,
since reduction in energy use reduces the amount of pollution generated in the
energy production step. Guided by this consideration, candidate options for
in-depth analysis were identified from the major energy consuming process steps
with known or potential environmental problems.
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After developing a list of candidate process options, we assessed
subjectively
• pollution or environmental consequences of the process change,
• probability or potential for the change, and
• energy conservation consequences of the change.
Even though all of the candidate process options were large energy-users,
there was wide variation in energy use and estimated pollution loads between
options at the top and bottom of the list. A modest process change in a major
energy consuming process step could have more dramatic energy consequences
than a more technically significant process change in a process step whose
energy consumption is rather modest. For the lesser energy-using process steps
process options were selected for in-depth analysis only if a high probability
for process change and pollution consequences was perceived.
Because of the time and scope limitations for this study, we have not
attempted to prepare a comprehensive list of process options or to consider all
economic, technological, institutional, legal or other factors affecting imple-
mentation of these changes. Instead we have relied on our own background
experience, industry contacts, and the guidance of the Project Officer and EPA
advisors to choose the following candidates for study in the glass industry:
1. Coal Gasification
2. Direct Coal Firing
3. Electric Melting
4. Coal, Hot Gas Generation (COHOGG)
5. Batch Preheating
6. Oxygen Enrichment of Natural Gas
7 - Submerged Burners
*
8. Electric Boosting Melting
9. Recycle Cullet
After discussion with the EPA Project Officer, his advisors, and industry
representatives, we chose the first five from this list for analysis because:
• Four of the first five systems involved a fundamental change in fuel
form from a critical fuel to a less critical fuel.
• Electric boosting melting is a current practice in a large number of
glass melting installations at the present time.
-------
• Submerged burners as presently conceived are known to have adverse
effects on glass quality and technical feasibility is very questionable
(Battelle Laboratories, 1974)
• The use of recycle cullet from municipal waste streams involves a
serious question of a socio-economic nature as well as the technical
feasibility of collection and separation. No new information could
be generated in this study to resolve these questions.
• Oxygen enrichment is considered a modification of present techniques,
thus is discussed qualitatively based on available information.
In this study, the glass industry description is based on 1972, the latest
representative year for the industry for which we had good statistical informa-
tion. Recognizing that capital investments and energy costs have escalated
rapidly in the past few years and have greatly distorted the traditional basis
for making cost comparisons, we developed costs representative of the first
half of 1975, using constant 1975 dollars for our comparative analysis of new
and current processes.
-------
II. FINDINGS AND CONCLUSIONS
A. FINDINGS
On the basis of the analysis of technical, energy consumption, pollution,
and economic factors for a typical present day natural gas-fired glass melting
operation and potential alternative melting processes, the principal findings
are as follows:
1. In the manufacturing of glass products, the melting unit process is
by far the most energy intensive. Natural gas, because of its ease
of handling, cleanliness, consistency and, until recently, its avail-
ability and low cost, is the primary energy form used in the United
States to melt glass.
2. Of the alternatives considered, coal gasification, hot gas generation,
direct coal firing and electric melting all involve the use of a less
critical form of fuel - coal. The total energy consumption with
each of these alternative glass melting unit processes is greater
than with natural gas (Table II-l).
3. At present, there are no proven technologies for the effective control
of air emission from a glass tank fired with natural gas or any of
the alternative fuel forms listed in finding 2. Effective scrubbing
and filter systems have not yet been demonstrated.
4. Coal gasification, hot gas generation and direct coal firing are
estimated to involve significant additional capital investment cost
arid increased operating cost per ton of glass produced. Direct coal
firing adds the least investment and cost, while coal gasification
increases both investment and manufacturing cost per ton the great-
est amount (Table II-2).
5. The use of the coal-based alternatives is expected to result in
increases in the amount of air emissions from the glass melting proc-
ess because of the greater gas volumes and additional airborne pollu-
tants from coal combustion. Additional solid waste and water effluent
streams also are involved in the separate processes of coal gasifica-
tion and hot gas generation and require further pollution controls
(Table II-3). Cost of pollution control for these processes could
be more economically significant than for the glass making process.
-------
TABLE II-l
SUMMARY OF ENERGY CONSUMPTION: GLASS MELTING UNIT PROCESS
(Basis: 200 tpd of glass)
Coal-Fired
Coal Hot Gas Particle*
Gasification Generation Electric Agglomeration
ENVIRONMENTAL
Electric Power
kWh/ton 24.48 26.85 46.71
Fuel Equivalent 0.25 0.28 0.49
(106 Btu/ton)
Fuel
(106 Btu/ton) 0.32 0.37 0.41
Total Fuel Equivalents
for Environmental Control 0.57 0.65 0.90
(106 Btu/ton)
PROCESS
Melting (10^ Btu/ton) 6.8 6.8 8.4
Controls (10& Btu/ton) 0.2 0.2 0.2
Total Fuel Equivalents
for Melting Process 7.0 7.0 8.6
(106 Btu/ton)
Total Energy Consumption 7.57 7.65 9.50
(106 Btu/ton)
30.82 1.78 14.79
0.32 0.02 0.16
0.45 0.01 0.21
0.77 0.03 0.37
8.4 JR 7 5.5
0.2 j8'2 0.2
8.6 8.2 5.7
9.37 '8.23 6.07
*Preheating with side port regenerative furnace.
-------
TABLE I1-2
SUMMARY OF INVESTMENT AND OPERATING COST FOR THE BASE CASE*
AND ALTERNATIVE MELTING UNIT FUEL PROCESSES AND PROCESS MODIFICATIONS
Facilities
Air Pollution Control
Water
Pollution Control
Solid Waste Control
00
Melting Unit Process
Natural Gas Firing
Investment ($000)
Operating Cost***$/ton
Coal Gasification
Investment ($000)
Operating Cost $/ton
Direct Coal Firing
Investment ($000)
Operating Cost $/ton
Coal-Fired Hot Gas Generation
Investment ($000)
Operating Cost $/ton
Electric Melting
Investment ($000)
Operating Cost $/ton *
Batch Preheat with/Natural Gas Firing
Investment ($000)
Operating Cost $/ton
Glass Auxiliary
Furnace Installation
1,404
72.67
1,404 1,380
91.74
1,404 355
67.17
1,404 1,560
85.17
1,624
76.02
1,404 500
72.94
Glass
Furnace
1,136
7.09
1,231
7.68
1,420
9.14
1,420
8.93*
304
2.12
951
5.18
Auxiliary Glass
Installation Furnace
95
0.64
1,066 95
6.00 0.64
192
1.38
95
0.64
(650)** 95
(2.57)** 0.64
95
0.64
Auxiliary Glass Auxiliary
Installation Furnace Installation
0.01
2.50 6.01 0.24
-
0.01 0.21
0.01 0.28
0,01 (0.18)**
0.01
Total
2,635
80.41
5,176
114.81
3,371
, 77.91
4,479
95.03
2,673
81.54
2,950
78.77
*Base Case - 200-tpd, Natural Gas-Fired, Side Port, Regenerative Furnace. Costs Reflect only Melting Cost.
**Cost of pollution control at power generation station prorated to glass plant.
***0perating cost $/ton = production cost plus pre tax return on investment @ 20%.
-------
TABLE II-3
'AIR, WATER, AND SOLID WASTE STREAMS FROM BASE CASE' AND ALTERNATIVE
FUEL SYSTEMS AND PROCESS MODIFICATIONS
Air Emission
Melting Unit Fuel Process
Natural Gas Firing
Coal Gasification
Direct Coal Firing
Coal-Fire* Hot Gas
Generation
Electric Melting
Batch Preheat with
Natural Gas Firing
Auxiliary
Installation
Glass Furnace
NO*, SOX,
particulates
Increased NOX, SOX, Sulfur removal*
particulates from from incoming
melt & batch gas stream
Increased NOX, SOy,
particulates
Increased NOjj, S
particulates
Reduced NOjj, SOX,
particulates
Reduced NOjj, SOX,
particulates
SC>2 power**
plant
Water Effluent Streams
Glass Furnace Installation
Scrubber purge
Solid Waste
Scrubber purge
Scrubber purge
Scrubber purge
Scrubber purge
Scrubber purge
Sulfur rec.
purge
Glass Furnace
Dust from fabric
filter
Scrubber sludge
Dust from filter
Scrubber sludge
Dust from fabric
filter, sludge
from scrubbers
Dust from filter
Scrubber sludge
Dust from fabric
filter
Scrubbier sludge
Dust from fabric
filter
Scrubber sludge
Installation
Ash
Sulfur rec.
Ash
Ash
Limestone
Ash
Power
Generation Plant
*Gas from producer subjected to sulfur removal before entering glass furnace.
**Indicates air and water streams at power generating station.
-------
TABLE II-4
QUALITATIVE COMPARISON OF THE ALTERNATIVE PROCESS ECONOMICS,
ENERGY, AND ENVIRONMENTAL IMPLICATIONS
(all relative to base case)
•^Factor
Process
Economics
•
Energy
Environment
Coal Gasification Coal Hot Gas Generator
Higher capital investment Higher capital investment
Higher operating cost Increased operating cost
Pollution control
energy consumption
higher
Increased energy for
melting due to
inefficiency in system
Increased air emis-
sion from glass
furnace but same
species
Slightly increased'
water effluent
Hew solid waste
stream (ash &
sulfur)
Increased energy consump-
tion in pollution control
equipment
Increased energy for
melting
Higher air emission
from glass furnace
Additional solid waste
stream (ash and
limestone)
Direct Coal Firing
Increased investment
cost
Slightly greater
operating cost
Slightly higher
energy consumption
for pollution control
Comparable energy
required in melting
Higher air emission
from glass furnace
Additional solid
waste stream (ash)
Electric Melting
Similar investment
requirements
Slightly greater
operating cost
Greatly reduced
energy consumption
for pollution
control
Increased energy
requirements for
melting due to loss
in transmission and
distribution
Greatly reduced air
emission from glass
furnace
Emission & solid
waste streams trans-
ferred to electric
power generation
source
Batch Preheat
Similar investment
requirements
Slightly lower
operating cost
Reduced energy
consumption for
pollution control
Reduced energy
.requirements for
melting
Reduced air emis-
sion from glass
furnace
-------
6. The electric melting process appears to be a technically and economi-
cally competitive alternative. Air emissions from the glass furnace
are substantially reduced in volume in electric melting and therefore,
the cost of pollution control required is much less. However, the
use of electricity as an alternative fuel form increases the magni-
tude of pollution emissions at the power generating plant.
7. Process modification to utilize heat from the melting furnace for
preheating the batch reduces overall energy consumption. Air emis-
sions from the glass furnace are reduced due to the lower fuel
requirement and the consequent lower exhaust gas volume. Pollution
control costs are correspondingly lower for the glass furnace. The
batch preheat process could be utilized with all the analyzed alterna-
tive fuel forms except electric melting (Table II-4).
B. CONCLUSIONS
1. There are no proven systems for controlling air emission from glass furnaces.
Economical and effective techniques for removal of sulfur and fine particulate
from stack gases are required.
2. Due to the lack of availability and increased cost of natural gas,
alternative fuel processes, principally coal-based, will be considered. All
the coal-based alternatives - i.e., coal gasification, hot gas generation, and
direct coal firing — greatly increase the emission loads from the glass furnace
and will require larger and more expensive systems.
3. Because of substantial investment cost and increased operating cost, proc-
esses such as coal gasification are not economically attractive alternatives
to natural-gas-fired furnaces at this time. Although economically attractive,
direct firing with coal is presently beset with serious technical problems
which are related to the effect of the ash on glass furnace refractories and
on glass quality; as such, its viability as an alternative is uncertain.
4. Electric melting undoubtedly will find increased use in glass melting.
Considerably lower gas volumes reduce the load on air emission control
requirements.
5. A form of batch preheating can be an effective way to reduce fuel require-
ments and, consequently, gas exhaust volume and pollution control costs. '
6. Emission species from the glass furnace, with few~exceptions, remain
essentially the same regardless of which fuel form or process modification is
used. By and large, the volume of air emission from the furnace increases
for all coal-based alternatives whereas electric melting and batch preheat
reduce exhaust volume.
7. Additional solid waste and water streams created by alternative processes,
although involving increased capital and operating costs, appear to be amenable
to existing technology.
-------
C. IMPACT OF EPA POLICIES ON FUTURE CHOICE OF ALTERNATIVES
1. Regulations relating to environmental quality of effluents and emissions
from coal generation of electricity will have impacts on the availability and
cost of power for melting glass.
2. Future air emission standards for glass furnaces relating to NOX, SOX,
and particulates will determine the costs of control. All coal-related alterna-
tive fuels increase emission. The choice of alternatives would be influenced
by these added costs, and the potential high cost of pollution control could
deter further development.
3. Trends toward electric melting and batch preheating process modification
could depend upon the specifics of any proposed air emission standards.
D. PRACTICES/PROCESSES REQUIRING ADDITIONAL RESEARCH
1. A proven system to control glass furnace emissions of SOx and particulates
must be developed if cost-effective pollution control is to be obtained. Such
a system is required if any of the coal-related processes is to be utilized.
2. The feasibility of a batch preheating process modification needs to be
demonstrated to stimulate implementation of this technique for energy conserva-
tion and pollution reduction. The technical and economic feasibility of a
preheat-agglomerate process modification is the subject of EPA's RFP
No. DU-75-A291.
3. Demonstration of the technical feasibility of producing quality glass
with economic furnace operation and life using direct firing of pulverized
coal would aid in conserving energy by utilizing the less critical form of fuel
with a minimum of intermediate steps and their cost in dollars and energy.
12
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III. INDUSTRY OVERVIEW
The U.S. glass manufacturing industry can be viewed as comprising four
.major segments based on its technology, products and markets, i^e., flat glass,
container glass, pressed and blown glass, and glass fibers, and a fifth seg-
ment, i.e., the products of purchased glass. The latter segment is not an
integrated glass-producing segment because it does not melt glass; it only
performs finishing operations. Compared to the four major segments the pro-
ducts from the purchased glass segment are low consumers of energy and will
not be considered in this study. Handmade glassware manufacturing is also
excluded from the analysis.
In total, the industry shipments in 1972 were valued at more than $4
Billion and were from approximately'400 plants in the United States. The
total industry employment is estimated to be 15,000. The largest single seg-
ment is glass containers, which probably accounts for 60% of the glass ton-
nage produced in this country. Of the total value of products, the glass
container segment represents 51%, wool and textile fibers 18%, pressed and
blown ware 17%, and flat glass 14% (Department of Commerce, 1972).
In general, the companies in the glass industry participate in one and
perhaps two segments but rarely does a single company have broad participa-
tion in more than two segments. In the flat glass and fiber glass segment,
the industry is concentrated in relatively few firms; 7 companies dominate
the flat glass segment and three companies produce 80-90% of the fiber glass
in the United States. The concentration is less intensive in the glass con-
tainer segment, although the eight largest of its 30 firms probably produce
75-80% of the product.
The markets for the industry are broad and very diverse. Therefore,
generalizing on the industry growth is difficult. Flat glass shipments are
heavily dependent on the automotive and construction industry. Some pressed
and blown ware are more closely tied to consumer spending for television,
lighting, and household goods. Wool fiber glass markets are dominated by
construction, both residential and commercial, whereas textile fibers are
used in marine, automotive, and construction products. The container glass
market is highly influenced by the beverage market, where glass competes
with aluminum and steel.
The future growth in the total glass industry is expected to continue
at much the same rate as its historic rate, which has been slightly less than
the GNP. The bulk of the glass production in the United States is concen-
trated in the East North Central, Middle Atlantic, and Pacific regions. The
major glass producing states are Illinois, Ohio, Pennsylvania, New York,
West Virginia, New Jersey, and California.
13
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In the glass industry the predominant energy sources are natural gas and
electricity. In 1972, in the four major segments natural gas accounted for
70% of the energy consumed by the industry; electricity, 20%. The remainder
was largely fuel oil. There are differences in the patterns of energy use
within each segment, but the basic fact is that natural gas is the predominant
fuel used to melt glass; and the melting step is the major energy consumer in
the entire glass manufacturing process. There have been no major shifts in
fuel consuming patterns in recent years. However, natural gas has been avail-
able only on an interruptible basis and standby fuel, principally propane and
oil, is necessary. Many plants now have provisions for using oil, particularly
in the winter months in New England and the Atlantic states.
14
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IV. COMPARISON OF CURRENT AND ALTERNATIVE PROCESSES
A. INTRODUCTION
1. Process Options Analyzed
In the analysis of the glass manufacturing process, two factors indicate
the likelihood of process changes that might be instituted by the industry
because of energy considerations. First, the melting process is by far
the most significant energy consuming unit process in glass manufacturing.
Second, natural gas is the predominant fuel for firing the melting furnace.
Since the availability of natural gas has been a major problem.for glass
companies for the past year and a half, alternative fuels, principally oil,
have been required to maintain production.
Therefore, alternatives to natural gas-fired melting processes are of
prime importance to the future and viability of the industry. The use of
fuel oil has and will continue to be an alternative in present furnaces for
melting. However, it is certainly not a panacea for the industry's energy
problems since the availability, cost, and supply of oil is certainly not
assured and will be influenced by world political and economic factors. An
even greater uncertainty would be an attempt to rely on propane for anything
more than a standby fuel. Propane's availability is limited and its cost
high. Basically the only fuel alternative that reduces the long-term risk
and uncertainties associated with the present fuels is coal - in one form
or another.
Therefore, alternatives based on coal as the primary fuel were given
the highest priority in this study. The approaches that were considered
are direct firing with coal, coal gasification, coal-fired hot gas generation,
and electricity based on generation from coal-fired power plants. In addition,
one process modification which is aimed at improving efficiency of utilizing
energy in the melting process was considered. The glass melting furnace as
it has evolved is not a highly energy-efficient operation: about 19% of energy
input to the furnace is consumed only in melting the glass. If the tern—
perature of the batch raw materials and cullet could be raised to the temper-
ature required for "fining" by a more efficient process, the overall energy
savings could be significant. Utilizing waste furnace heat, one approach
would be to preheat the batch, preferably in an agglomerate form to reduce
dusting and improve heat transfer prior to adding the batch to the furnace.
By and large, a number of modifications of glass furnaces can be made,
particularly in their operating parameters, to improve efficiency and reduce
fuel consumption: e.g., reduction of structural losses (insulation),
15
-------
reduction of stack losses, improved port geometry, use of oxygen (see
Appendix C), etc. Many of these are now common industry_practice and energy
conservation may be achieved in situations in which no major process modi-
fications have to be made.
2. Basis of Production Cost Analysis
The costs of raw materials were based upon delivered costs in the first
half of 1975 at the glass plant.
The energy costs for coal and natural gas were based upon the prices paid
in March 1975 by electric utilities for the East North Central (ENC) region,
which contains the greatest portion of container glass manufacturing plants.
We have found that such prices are consistent with prices reported by SIC
sector in the 1972 Census and escalated by fuel cost indices to 1975. But the
gas and electric utility industries are largely regulated and the 1975 (first
half) price would not be indicative of what a new plant built upon a green-
field site would have to pay for energy. The cost of natural gas for such
new facilities may well equal that of oil.
The cost of cooling water was based upon 3
-------
B. CURRENT PROCESS (BASE CASE)
1. Process Description
In the U.S. glass industry approximately 90% (Arthur D. Little, Inc.,
1975) of all glass is melted in regenerative furnaces. These furnaces are
fired with natural gas as the primary fuel. Presently, two types of regenera-
tive furnaces are used: side port and end port. Basically they perform
quite similarly. Because of its ability to incorporate a greater checkers
volume than the end port furnace, the side port regenerative furnace has
higher pull rates; therefore, in t.his country more glass is melted in this
type of furnace. In terms of energy consumption per ton of glass melted,
initially the end port furnace consumes less energy, but subsequently the
checker volume decreases through plugging, and over the life of the furnace
melting efficiency becomes somewhat less than that of the side port furnace.
Presently, in the United States more than 50 different glass compositions
are being melted. However, approximately 95% of the total tonnage shipped
consists of soda-lime glass. This glass contains about 72% silica, 14% soda,
and 9% calcia by weight (Arthur D. Little, Inc., 1975; and Tooley, 1974).
In essence, glass melting in the United States may be represented by the
melting of soda-lime glass in a natural gas-fired, side port, regenerative
furnace.
On the basis of our experience, to simplify comparison with alternative
processes for melting glass, we have fixed a set of operating conditions for
what may be termed the base case (Table IV-1) so we can compare alternative
processes to the base case in terms of changes in capital investment and
operating costs, differences in degree and type of pollutants,~ and changes
in energy melting efficiency.
A natural gas-fired, side port, regenerative furnace is quite consistent
with normal practice. On the basis of conversations with glass manufacturers
and glass tank designers, we chose a pull rate of 200 tons per day (tpd). Soda-
lime glass was chosen because it accounts for the bulk of glass being manu-
factured in the United States. Feed rate was based upon typical soda-lime
formulations, which indicated that 1200 pounds of raw materials are required
to produce 1000 pounds of glass, hence at a 200 tpd pull rate, 2QO x 1200/
1000 or 240 tpd of raw material are required. To establish fuel prices and
wages, as well as other costs, an East North Central location was chosen
because the area has the largest single concentration of g-lass manufacturing
plants. Finally, an estimated overall efficiency of 90% was taken as the
industry standard, hence at a pull rate of 200 tpd, the amount of saleable
glass would be about 180 tpd. These assumptions are consistent with industry
practicej and any variation in actual practice from these operating assump-
tions will not affect any of our conclusions.
17
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TABLE IV-1
OPERATING ASSUMPTIONS FOR BASE CASE
• Furnace Type - Side port, regenerative
• Fuel - Natural gas
• Glass Type - Soda-lime
• Plant Location - East North Central
• Pull Rate - 200 tons per day
• Feed Rate - 240 tons per day
• Efficiency - 90%, or 180 tons per day
The major raw materials -which make up a soda-lime glass are silica sand,
feldspar, dolomite, limestone and soda ash. Silica, or silicon dioxide, is
the most important constituent in common commercial glasses. As it is the
principal glass-forming oxide, silica or glass sand typically arrives at the
glass plant by rail, is between 20 mesh and 100 mesh, contains between 99.6
and 99.8% Si02> and is very low in iron, i.e., less than 0.025%. Feldspar
is used primarily as a source of alumina, but contributes some fluxing to the
batch because of its soda and potash content. Feldspars, in general, are
represented by the formula R20'A1203-68102 (where R20 represents the alkali
content). Dolomite and limestone are used as a source of calcia, the dif-
ference in the two being the much higher magnesia content in the dolomite.
In addition to some fluxing, the purpose of the feldspar, dolomite, and
limestone is to impart chemical durability to the glass, which is related
to the RO-to-silica ratio and the alumina content. Soda ash is the primary
fluxing agent in the batch. Fluxing, or lowering of the melting point,
which imparts an improved workability to the glass, is accomplished by the
Na20 in the soda ash.
Prior to melting and feeding into the furnace, these raw materials - i.e.,
silica, feldspar, dolomite, limestone and soda ash—are carefully weighed
and blended along with a number of other minor batch ingredients.
18
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In a typical side port regenerative glass melting furnace (Figure IV-1),
the box type regenerative checkers are on opposite ends, as are the burner
ports, hence the term side port regenerative. In the end port regenerative
glass melting furnace, the burner ports and checker structure are at one end.
The checker structure is made up of a lattice of brickwork which allows the
passage of air to support combustion. The checkers use waste heat to heat
the incoming air for combustion, thereby providing higher flame temperatures
and greater melting efficiency. An air-reversing valve channels the incoming
air through one checker system and then the other.
Typically, the operation is as follows. Incoming air for combustion is
heated as it passes through the hot checker system. This hot air meets the
fuel in the burner port. The flame then burns over the surface of the glass
within the space under the melter crown. The combustion gases leave the melt-
ing area through the-opposite burner ports and through the other checker
system, thereby heating these checkers. The furnace is operated in this
mode for about 20 minutes before the flow is reversed through the other checker
and port system. (Tooley, 1974)
Glass flow is perpendicular to the checkers and burners. The incoming
glass-batch powders, which are a carefully premixed formulation of primarily
silica, feldspar, dolomite, limestone, and soda ash, are fed across the melt
at one end of the furnace. Due to the flow of the combustion gases over the
glass powder as it is being melted, some particulate matter carries over to
the checkers; to reduce carryover, it is critical to eliminate fine particles,
i.e., those less than 100 mesh. To reduce dusting during mixing and feeding,
the batch ingredients are wetted with about 2-3/4 gallons of water per ton of
glass. The glass then moves through the melter from the feed, or dog-house,
end to the finer.
The highest temperature in the melter is about 2920°F; at only slightly
higher temperature, approximately 2950°F, the silica crown roof begins to
soften and drip, thereby causing inhomogeneities which lead to rejects in
the final glass product. Typical design specifications call for about 5 feet
of melting area per ton of glass pulled per day. Hence, for a typical side
port, regenerative furnace with a 200 tpd capacity, a melting area of about
1000 ft2 would be required.
2. Energy Considerations
In general, the energy required to melt glass is influenced by batch com-
position, furnace size and design, and by the age of the furnace. For the
melting of a soda-lime glass in a given side port regenerative furnace, the
primary energy variable is furnace age. As a furnace ages, the spacing
between checker bricks decreases because of carryover of unmelted particles
from the raw batch by the combustion gases. These particles react and stick
to the hot refractory brickwork. As aging continues, areas of the checkers
eventually become plugged, or, due to the additional weight buildup, brick-
work in the lower regions of the checkers collapse. The end result is a
decrease in checker volume, hence a reduction of air preheating (Alexander,
1974), lowering of flame temperature and decrease in melting efficiency
(Figure IV-2).
19
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Silica Crown Roof ,— Insulating Refractory
Regenerator Crown
Regenerator
Checkers
Floor Line
Regenerator Arch
Figure IV-1. Typical Side Port Regenerative Furnace
-------
_c
'>
CO
CD
55 \-
50
45
40
35
£ 30
p
25
20
15
10
1200 1600 2000
Preheat Temperature ° F
2400
Figure IV-2. Fuel Savings Due to Regeneration
21
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For an operation involving the melting of soda-lime in a gas-fired, side
port, regenerative furnace, energy inputs vary from 5 to 9 x 10° Btu per ton
of glass. For a 200 tpd operation, the typical energy required is about
6.8 x 10^ Btu/ton. Approximately one-third of this energy is required to
melt the raw materials entering the furnace, one-third is lost through the
refractories, and one-third is lost up the stack. During the past 20 years
the energy required to melt glass has dropped by nearly 50% (Hamilton, 1970).
This considerable energy savings was made possible through better use of
insulation, and through better burner and furnace design. Further improve-
ments in energy utilization by increased insulation is minimal. The outside
walls of the tank have to be water-cooled to extend the life of the furnace,
consequently such heat losses through the refractories will remain high.
Increased utilization of waste heat does however appear to be a reasonable
approach to improve melting efficiency.
3. Economic Considerations
• •• • "• i «
In this section, we give the investment and the operating costs for the
melting process only; therefore, they do not reflect total manufacturing or
investment costs.
a. Fixed Capital Investment
The fixed capital investment for a natural gas-fired, side port, regener-
ative furnace having a pull rate of 200 tpd is approximately $1.4 million.
(The pollution control cost for a furnace of this type and size is covered
in a latter part of this section.)
b. Production Cost
The total production cost for melting a soda-lime glass, including preta>
ROI, is $72.67/ton (Table IV-2).
c. Raw Materials Cost
Costs of raw materials were calculated by obtaining delivered bulk mate-
rials costs for the various ingredients which make up a typical soda-lime
glass batch and multiplying these costs by their required weight ratio
(Table IV-3). The composition of a soda-lime glass does not differ signifi-
cantly, hence raw material costs do not change significantly from one plant
to another plant or for one process or another. The delivered raw material
cost was estimated at $46.13 per ton of glass shipped.
d. Energy Costs
A 200 tpd glass furnace needs approximately 6.8 x 10^ Btu to melt a ton
of glass. "Typically, this energy input varies between 5 and 9 Btu per ton
of glass, depending upon furnace age, type, and size. The cost for natural
gas was obtained by averaging the purchased price of this fuel in the East
North Central region - which produces the majority of the glass manufactured
22
-------
TABLE IV-2
PRODUCTION COST ESTIMATE: NATURAL GAS-FIRED, SIDE PORT,
REGENERATIVE FURNACE - BASE CASE
Product: Soda-lime Container Glass
Daily Capacity: 200 tons
Annual Production: 65.700 tons
Location: East North Central
Fixed Investment: $1,404.600
VARIABLE COSTS
Raw Materials & Shipping*
• Sand
• Feldspar
• Dolomite
• Limestone
• Soda Ash
Energy
• Purchased Gas
• Electricity
Water
• Process
• Cooling
Direct Operating Labor
Direct Supervisory Labor
Maintenance Labor
Maintenance Supplies
Labor Overhead
Miscellaneous Variable Costs
TOTAL VARIABLE COSTS
FIXED COSTS
Plant Overhead
Local Taxes & Insurance
Depreciation - (@ 14 yr)
TOTAL FIXED COSTS
TOTAL PRODUCTION COST
RETURN ON INVESTMENT @ 20% PRETAX
TOTAL
Units Used in
Costing or
Annual Cost
Basis
Net ton
Net ton
Net ton
Net ton
Net ton
106 Btu
kWh
1000 gal
1000 gal
Man-hour
Man-hour
$/Unit
20
34
63
20
68
2.06
0.0205
0.20
0.03
5.03
7.29
Units Consumed
per Ton of
Product
0.758
0.072
0.132
0.116
0.263
6.8
19.0
0.00275
0.275
0.19
0.02
Cost per Ton
of Product ($)
15.16
2.45
8.32
2.32
17.88
14.00
0.39
0.00
0.01
0.96
0.15
0.86
0.86
0.69
1.39
65.44
0.99
0.43
1.53
2.95
68.39
4.28
72.67/ton
*See Table IV-3.
23
-------
TABLE IV-3
BREAKDOWN OF RAW MATERIAL WEIGHTS AND COSTS
Basis of Calculation (%) ;
Pounds
678.9
64.5
118.0
104.2
235.7
Raw Material
Sand
Feldspar
Dolomite
Limestone
Soda Ash
Cost/
Ton($) SiO,
20 675.5
34 44.5
63
20
68
CaO Na^(
1.3 3.2
36.6
52.1
- 137.9
3.4
»
11.6 - 3.9
24.8
5.2-
720.0 90.0 141.1 15.0 30.0 3.9 (1000)
in the United States. In addition to the natural gas, some electrical energy
is also required for instrumentation and controls. Typically, glass manufac-
turers consume about 1 x 10" Btu of electricity per ton of glass; of this,
about 5-10% is estimated to be associated with melting (exclusive of electri-
cal boosting).
e. Wages
Wage rates were determined by averaging production and nonproduction
wages in this industry for the major mid-West glass producing states. The
number of production employees for melting was taken as six, and the super-
visory labor was taken as a fixed percentage, based upon the industry average,
of the production labor.
f. Maintenance Labor and Supplies
Maintenance labor and supplies was taken as 6% of fixed capital
investment.
24
-------
g. Overhead
Plant and payroll overhead was taken as a fixed percentage of total
labor. This includes maintenance labor which was taken as one-half of
maintenance labor and supplies. A figure of 50% was used for plant overhead
and a figure of 35% for payroll overhead.
h. Other Fixed Costs
Taxes and insurance were taken as 2% of the fixed capital investment of
the glass melting furnace and depreciation was taken as 14 years straight
line.
i. Miscellaneous Variable Cost
The miscellaneous variable cost figure, covering primarily the costs
associated with the -purchase and shipment of the minor batch ingredients
(Table IV-4) was estimated .at 3% of the raw materials cost. Many of the
serious pollutants stem from these minor ingredients, such as sulfates. These
ingredients have to be specific, and as' such are quite critical to the batch.
Primarily, they are used as fluxing agents, to lower melting temperature
and to improve workability of the glass, or as fining agents to remove bubbles
from the glass.
TABLE IV-4
TYPICAL COMMERCIAL GLASS BATCH MINOR ADDITIVES
Oxide Material Source
Antimony Oxide Stibnite
Arsenious Oxide Arsenious Oxide
Barium Oxide Barium Carbonate, Barium Sulfate
Boric Oxide Borax, Boric Acid, Colemanite
i
Fluorine Oxide Cryolite, Fluorospar
Phosphates Bone Ash, Apatite
Lithia Lithium Carbonate
Zinc Oxide Zinc Oxide
Zirconia Zircon
•25
-------
4. Environmental Considerations
a. Air Pollution
The air pollution emissions from a glass melting furnace include partic-
ulates, nitrogen oxides, sulfur oxides, and in some cases minor emissions of
hazardous materials, such as fluorides, arsenic, lead, and a few others. (A
detailed discussion of these emissions is contained in Source Assessment
Document No. 3, Glass Manufacturing Plants, EPA Report No. 68-02-1320,
November 1974, which we have relied upon heavily for most of the emission data
reported here.)
Depending upon the glass composition and specific minor ingredients, the
glass melting operation can result in the emission of particularly hazardous
materials. The characteristics of the air pollutants, the control technology,
and cost of control are all discussed in the following subsections.
(1) Characterization of Air Pollution Emissions
A glass melting furnace has both particulate and gaseous emissions
which must be controlled (Table IV-5).
The major gaseous pollutant is nitrogen oxide, which is formed during
the combustion of natural gas. Because of the high temperatures required
for the furnace, the gas combustor must be operated at temperatures favorable
to nitrogen oxide formation.
The sulfur oxide emissions arise from two sources: sulfur in the fuel
and decomposition of mineral sulfates in the glass melt. The sulfur within
the fuel is usually a minor source of sulfur oxide emissions and generally
results in the production of S0£. The decomposition of mineral sulfates in
the melt produces sulfur in the form of 803, which is much more corrosive
than S02. Although some of the 863 decomposes to SC>2 at temperatures above
2790°F, some will remain in the form of 803. If the furnace gases are cooled
to below the acid dew point (about 230°F), the 803 will condense with water
vapor to form sulfuric acid mist, which is corrosive and a serious health
hazard.
Two classes of particulates should be considered: those entrained by
the hot combustion gases and those formed by the volatilization of materials
in the glass melt. The latter are by far the more hazardous because they
are submicronic and are in the form of sulfate salts with trace quantities
of fluorides, lead, arsenic, boron, or other heavy metals, depending upon
the type of glass that is produced. For example, opal glass generates a con-
siderably greater amount of fluorides than soda-lime glass; lead emissions
are found primarily in lead glass; and arsenic and selenium are common con-
stituents in some tinted glass.
In addition, there are emissions of carbon monoxide and hydrocarbons,
both of which are believed to be the result of incomplete fuel combustion or
decomposition of powdered coal in the batch which is sometimes added to reduce
sulfate to sulfite in the melt. These emissions, considered to have a minor
impact, are easily controlled.
26
-------
TABLE IV-5
GLASS MELTING FURNACE EMISSIONS
Emission Rate
Species Ib/ton of Glass Produced
N0x 8
SO 3
x
Particulates 2
CO 1
Hydrocarbons 0.2
Arsenic 0.6
Selenium 0.03
Antimony 0.1
C12 or HC1 O-1
Fluorides 22
(opal glass)
Fluorides 0.1 0.05
(soda-lime glass)
Lead 10 5
Borates 20 10
Source: Assessment Document No. 3, Glass Manufacturing Plants, EPA
Report No. 68-02-1320, November 1974.
(2) Control Technology
(a) Gaseous Emissions - The only viable control technique for nitrogen oxide
at the present time is maintaining the proper combustion conditions in the
furnace. For example, low excess air firing and no air preheating both pro-
duce minimum nitrogen oxide emissions. As is the case with utility boilers,
the control of nitrogen oxides is based upon modification of combustion con-
ditions, and the costs of control are included as a part of the furnace
manufacturing costs.
The sulfur oxide emissions are expected to have an abnormally high con-
centration of 303 as opposed to SOo in the stack gas. This is expected to
increase the corrosion potential of the stack gas and make air pollution
control more difficult, more costly, and more necessary. The control tech-
niques for SC>2 and 803 consist of contacting the gases with caustic or lime
to convert the gaseous emissions to sulfate or sulfite salts of sodium and
calcium. Scrubbers for this purpose should utilize high efficiency entrain-
ment separators to avoid carryover of sulfuric acid mist to other control
devices into the stack.
(b) Particulates - The particulates present the most difficult of the control
problems encountered in the glass melting furnace. In the submicron particle
range typical of glass furnace emissions (Figure IV-3), the collection effi-
ciency .of most air pollution control devices falls off drastically (Figure
IV-4).
27
-------
oo
m
T3
e
S.
0.6 i
0.5
0.4
0.3
0.2
0.1
0.05
0.04
0.03
0.02
0.05 0.2
Flint glass
•Amber glass
2 5 10 20 30 50 70 80 90 95 98 99
Percent by number equal to or less than indicated size
99.8
Figure IV-3. Log-Probability Distribution of Particle Sizes
Present in Glass Furnace Effluent
-------
100
_ 90
-g 80
70
High-Efficiency
Cyclone
Medium-Efficiency
Cyclone
0.2 0.3 0.4 0.6 0.8 1.0
Source: Arthur D. Little. Inc.
2.0 3.0 4.0 6.0 8.0 10.0
Particle Diameter (microns)
20
30 40 60 80
Figure IV--4.. Performance Comparison for Particulate Control Systems
-------
At present, there are very few particulate control devices that have
been demonstrated on glass melting furnaces. The use of high-efficiency wet
scrubbers has been suggested because of the advantage of being able to treat
the acid stack gases at the same time that particulates are removed. However,
pressure drops as high as 65 inches of water have resulted in particle col-
lection efficiencies of only 95%.
Conventional electrostatic precipitators have collection efficiency
limits similar to those of wet scrubbers. NAFCO Engineering, Ltd., using
a precipitator specifically designed for glass furnaces in Japan, has obtained
slightly higher efficiencies. This technology is available in the United
States as well.
The highest collection efficiency is generally attained using fabric
filters. In the United States, several demonstrations carried out with dif-
ferent types of bags have shown efficiencies in excess of 99%. On 'the other
hand, fabric filters are very susceptible to blinding by the condensation
of vapors within the fabric. This has been a particularly bothersome prob-
lem in the glass industry because of the acid mist carryover, suggesting that
for the system to work effectively, careful regulation of gas temperatures
will be required.
(3) Cost of Control
Because of a lack of proven technology for both the gaseous and partic-
ulate emissions very few of the glass melting furnaces in the United States
are controlled. Therefore, there is no "typical" air pollution control
system readily available to serve as a basis for calculation of typical costs
of control.
In the absence of a clear-cut consensus on appropriate control technology,
we have assumed what we believe will be an adequate control system (Figure
IV-5) and have based our cost estimates upon this assumption (Table IV-6).
In this type of control, S02 and 803 emissions are removed by a spray scrubber
with soda ash as a neutralizing agent. The scrubber is not intended as a
particulate control device and will be operated at low energy. However,
many of the large particulates, including those entrained by the combustion
gases, will settle out and be discharged with the scrubber purge. The purged
wastewater must be further treated prior to discharge from the plant.
The gases leave the scrubber at approximately 120°F (the dew point of
the combustion gases) and are reheated to approximately 250°F prior to enter-
ing the fabric filter, where the particulates are removed. The reheat is
necessary to prevent condensation of water vapors or acid mists within the
fabric filter which would blind the fabric surface.
b. Water Pollution
The wet scrubber used on the glass melting furnace is operated in a
recycle mode with a small purge stream. The purge stream will contain high
concentrations of particulate material, sulfites, sulfates, and trace metals,
such as selenium, boron, and arsenic.
30
-------
Exhaust
Na2CO3
(to land fill)
To Water
Glass
Furnace
Figure IV-5. Air Pollution Control System for Glass Melting Furnace
TABLE IV-6
AIR POLLUTION CONTROL COSTS
(Basis: 200 tpd of glass)
CAPITAL COSTS ($)
Spray Scrubber System 434,200
Reheater 49,700
Fabric Filter 389,800
Total Direct Costs 873,700
Indirects @30% of Direct Costs 262,100
TOTAL CAPITAL COST 1,135,800
ANNUAL OPERATING COSTS ($/yr)
Direct Costs
Labor (plus Supervision and Overhead),
1/2 man/shift @$9.25/hr (total) 40,500
Maintenance @5% of Capital 56,800
Utilities
-Electric Power, 1.54 x 106 kWh/yr @$0.0205 31,600
-Fuel, 23.31 x 109 Btu/yr @$2.06/106 Btu 48,000
-Water, 19.5 x 106 gal/yr
-------
The estimated flow rate at the purge system is 7200 gallons per day
(gpd). While the exact composition of this wastewater stream cannot be
quantitatively predicted, it is reasonable to expect that treatment with
lime and coagulants will substantially reduce the quantity of suspended solids
and dissolved heavy metals.
A treatment system is envisioned that would consist of precipitation/
coagulation, sedimentation, filtration, and sludge thickening (Table IV-7).
Sludge from the wastewater treatment system will contain heavy metals and
cannot be disposed of indiscriminately.
c. Solid Waste Disposal
The solid wastes from this process are the sludge from the water treat-
ment plant and the dust from the fabric filter. We have assumed that these
will be disposed of by contract at a cost of approximately $5/ton. The total
cost is about $0.01/ton of glass.
C. COAL GASIFICATION
1. Process Description
Generally, coal gasification processes include, in some variation, the
following steps:
• coal handling and storage
• coal preparation
• gasification
• oxidant feed facilities
• gas cleaning
The variations depend on the peculiarities of each type of gasifier and the
type of fuel used. A coal gasification system suitable for a glass manufac-
turing operation is either a single-stage gasifier (Wellman-Galusha) or a
two-stage gasifier.
Coal of any rank with a low swelling index can be gasified in the Wellman
producer. The coal must be sized to the range -of about 3/8" to 2-1/2". Under-
size can cause bridging whereas oversize may reduce mass transfer rates and
affect gas distribution.
Predrying of the coal is only necessary to the extent that surface j
moisture may cause fines to cling to the larger coal particles during screening.
In an oxygen-blown system, the total moisture may affect economics to the
extent that more coal must be burned in the gasifier to vaporize the moisture.
Depending on the coal, therefore, a drier may be warranted.
32
-------
TABLE IV-7
WASTEWATER TREATMENT COST: GLASS MELTING VIA
NATURAL GAS-FIRED FURNACE - BASE CASE
(Basis: 200 tpd - 365 days/year Production)
CAPITAL INVESTMENT
$95,000
Operating Cost
Direct Operating Costs
Labor (plus supervision & overhead)
Maintenance
Chemicals
Electricity
Sludge Disposal
Total Direct Operating Costs
Indirect Costs
Depreciation, 14 years
Taxes and Insurance (@2%)
Total Indirect Cost
Return on Investment (@20%)
TOTAL ANNUAL COST
Unit Cost ($/ton of glass)
$10,200
3,800
500
1,400
3.200
$19,100
$ 6,800
1,000
$ 8,700
$19.000
$46,800
0.64
NOTES:
1) Treatment consists of:
- precipitation/coagulation
- sedimentation
- multi-media filtration
- sludge thickening
2) Capital investment adjusted to March 1975 (ENR=2126)
3) Quantities:
a) labor - 1050 man-hours/yr @ $9.75/man-hour (including supervision,
labor overhead, and plant overhead)
b) chemicals - 2.2 tpy hydrated lime @- $100/ton; 1.1 tpy sulfuric acid
@ $100/ton; 40 Ib/yr coagulant @ $1.00/lb
Electricity - 65,400 kWh/yr @ $0.0089/kWh
Sludge - 630 tpy (wet basis) @ $5.00/ton
33
-------
The Wellman-Galusha concept (Nelson, Applied Technology)(Figure IV-6) is
a singles-stage, fixed-^-bed gasifier which operates at atmospheric pressure
using oxygen, or air, and steam. Coal is fed through a rotating drum feeder
to the top of the bed, and slowly falls through the vessel as the coal is
gasified and ash is removed through the eccentrically rotating grate at the
bottom. Oxidant and steam are injected at the bottom to initiate the gasifi-
cation and combustion reactions. These hot, gaseous products rise through
the bed, heating and devolatilizing the coal before leaving at about 1000°F
at the top of the gasifier.
The vessel is constructed of water-jacketed, unlined steel. The steam
generated in the jacket is more than sufficient for process purposes (about
10-15% excess).
Except when operated on anthracite, the Wellman-Galusha gas contains con-
siderable tars which condense in distribution headers in large quantities.
Generally, the plant must be shut down every two weeks or so to burn out the
deposits in the headers and distribution lines, an expensive and unsafe
operation.
To avoid the tar problem, a two-stage version of the gasifier has been
developed to allow for removal of two separate gas streams from the gasifier,
one a tar-rich and the other a tar-free gas. The former may then be treated
for tar droplet removal via cyclone. Before distribution to the users, the
cool gas, now containing only a small quantity of tar droplets, is .mixed with
the hot gas stream (after dust collection) to vaporize any remaining tar. The
product gas is referred to as a hot raw gas.
Alternatively the gas may be further processed to produce a cold, clean
gas. For virtually complete tar removal, the tar-rich gas is treated as
above with the addition of an electrostatic precipitator. Meanwhile, the
hotter, bottom gas is cooled in a spray column. The gases are then mixed
upon entry into a cooler, after which any condensed light oils may be sepa-
rated and recovered,
2. Energy' Considerations
For purposes of comparison it was assumed that the same energy input is
required to melt glass with a low-Btu bituminous producer gas as it is with
natural gas, namely 6.8 x 10" Btu per ton of glass. Furthermore, a coal
w^tth. a fixed heating value, sulfur, and moisture content was used for this
coalrsEired process as well as for the other two which will be discussed later.
These values were fixed as follows:
Heating value (Btu/lb coal) 11,100
Sulfur content (%) 3.2
Moisture content (%) 12.5
Ash (%) 9.6
From this, it was calculated that
6.8 x 10 Btu . Pound of Coal . ton
ton 11,100'Btu 2000 Ib
34
-------
Ul
Ln
Coal Icoli
\ Preparation
O
Boiler Feedwater
Jacket
Steam
Gasifier
Air
D starrer
Tar
Deoiler
Oil
Product Gas
Figure IV-6. Wellman Two-Stage Gas Process
-------
or 0.31 ton of coal is required to melt one ton of glass. However, the
efficiency of the gasifier must be taken into account, and, assuming an 80%
conversion efficiency, 0.38 ton of coal (Arrandale, 1974a) is required per
ton of coal. Also, in this comparison a coal cost of $20 per ton was assumed.
3. Economic Considerations
a. Capital Investment
The incremental capital cost of a coal gasifier capable of producing
sufficient energy to melt 200 tpd of glass, including equipment installation
But excluding pollution equipment, is estimated to be $1,380,000. Furthermore,
this capital cost does not include the glass melting furnace cost; the assump-
tion has Been made that essentially no difference in glass furnace cost will
Be incurred when using this method of melting glass versus melting with natural
gas firing.. This additional investment is reflected by a $1.91 increase in
the fixed portion of production cost.
b. Production Cost (Table IV-8)
(1) Raw Materials
Raw materials costs for this case and the base case are expected to
remain essentially unchanged.
(2) Energy
On the basis of our operating assumptions, we have calculated that an
decrease of $6.79 per ton of.glass will be incurred by a switch in energy
generation form from natural gas to coal. This amounts to a fuel-energy
savings of about 55%.
(3) Labor
Additional direct labor is required to operate the gasifier and an
increase of $3.87 per ton is estimated. This amounts to a 400% increase in
direct labor.cost. This additional labor is also reflected in supervisory
labor, payroll overhead, and plant overhead. It is estimated that the total
increase will be $10.27 per ton, or 368% relative to the base case.
(4) Maintenance Labor and Supplies
Because of the increased equipment associated with the gasifier, an
increase in maintenance cost estimated at $4.43 per ton of glass will be
incurred relative to the base case, which is an increase of 257%.
(5) Miscellaneous Variable Costs
It is estimated that operating supplies, which make up the major portion
of this category, will also increase. This increase has been estimated at
$4.67 per ton of glass shipped, which is an increase of 336%.
36
-------
TABLE IV-8
PRODUCTION COST ESTIMATE: COAL GASIFICATION
Product: Soda-lime Container Glasa
Daily Capacity: 200 tons
Annual Production: 65,700 tons
Location: East North Central _
$1,380,000 + $1,404,600
Fixed Investment: for glass melting furnance
VARIABLE COST
Raw Materials & Shipping
• Sand
• Feldspar
• Dolomite
• Limestone
• Soda Ash
Energy
• Purchased Coal
• Electricity
Water
• Process
• Cooling
Direct Operating Labor
Direct Supervisory Labor
Maintenance Labor
Maintenance Supplies
Labor Overhead
Miscellaneous Variable Cost
TOTAL VARIABLE COST
FIXED COST
Plant Overhead
Local Taxes & Insurance
Depreciation
TOTAL FIXED COST
TOTAL PRODUCTION COST
RETURN OH INVESTMENT
TOTAL
Units Used in
Costing or
Annual Cost
Basis
Net ton
Net ton
Net ton
Net ton
Net ton
Net ton
kWh
1000 gal
1000 gal
Man-hour
Man-hour
1
$/Unit
20
34
63
20
68
20
0.0205
0.20
0.03
5.03
7.29
Units Consumed
per Ton of
Product
0.758
0.072
0.132
0.116
0.263
0.38
19.0
0.00275
0.275
0.96
0.11
Cost per Ton
of Product ($)
15.16
2.45
8.32
2.32
17.88
7.60
0.39
0.00
0.01
4.83
0.82
3.08
3.08
3.05
6.05
5.04
4.36
0.85
3.02
8.23
83.27
8.47
91.74/ton
37
-------
4. Environmental Considerations
a. Air Pollution
When coal gasification is used to generate a gaseous fuel for the glass
melting furnace, the major environmental difference is not in the glassmak-
ing process, but rather in the fuel generating process for the furnace. The
implications of this on the fuel-generation process and the glass-melting
process are discussed in the following subsections.
(1) Fuel Generation
The fuel gas produced in the coal gasifier will contain sulfur, mainly
in the form of H2S. So that excessive S02 emissions do not occur, the sulfur
must be controlled either before or after gas combustion in .the furnace. Two
control technologies could be considered: a sulfur-recovery process, such
as the Stretford process, to remove H^S from the fuel gas prior to burning
the fuel in the furnace, or flue gas desulfurization, such as the processes
currently used on utility boilers for removing SC>2 from exhaust gases. The
latter case is the same as the control for direct coal firing (which is dis-
cussed elsewhere in this report). As previously noted, a large increase in
the sulfur loading of the exhaust would greatly increase the problem of air
pollution control for the glass furnace, and the fluctuation in control costs
could be considerable. We have, therefore, included for comparison the alter-
native of removing sulfur as I^S prior to firing the fuel into the glass
furnace. The Stretford process is an example of appropriate sulfur recovery
technology for this application. The capital cost for a Stretford plant was
estimated for a 200 tpd glass melting furnace, based on the sulfur recovery
rate of 2.2 long tons per day (Table IV-9).
(2) Glass Furnace Controls
Once the H^S has been removed, the only difference between the base case
and the heating of a glass furnace using fuel gas from a coal gasifier is
that the exhaust gases for the coal gasifier case will be slightly greater
in volume than those of the base case (Table IV-10). There is about a 10%
difference in the gas flows between the coal gasification case and the base
case. As a consequence, the air pollution control system for the furnace
using fuel gas will be correspondingly larger in size, and the costs of con-
trol will reflect this difference. The air pollution control costs (Table
IV-11), based upon the utility requirements (Table IV-12), and the energy
consumption for the coal gasification case are only slightly greater than
the corresponding costs and utility requirements for the base case.
b. Water Pollution
The coal gasification alternative will produce two wastewater streams j,
a wet scrubber stream (of essentially the same size and composition as that
described under the base case), and a small wastewater stream from the
Stretford unit. In addition there will be the usual coal storage run-off
wastewaters that may have to be treated.
38
-------
TABLE IV-9
SULFUR CONTROL COSTS FOR COAL GASIFIER
(Basis: 2.2 long ton/day Sulfur Recovered via Stretford Process)
Annual Operating Cost ($/yr)
Direct Operating Costs
Labor (plus supervision & overhead),
1/3 man/shift <§ $9.25/hr (total) 27,000
Maintenance @ 5% of Capital 53,300
Utilities
- Electric Power, 2000 kWh/long ton @ $0.0205/kWh 32,900
- Fuel (3.8 x 106 Btu/long ton @ $2.06/106 Btu 6,300
- Cooling Water (250,000 gal/long ton @ $0.03/ 6,000
1000 gal
Chemicals @ $2.50/long ton 2,000
Total Direct Costs ($/yr) 127,500
Indirect Costs ($/yr)
Depreciation 76,100
Local Taxes & Insurance @ 2% Capital Investment 21,300
Total Manufacturing Cost 97,400
Return on Investment @ 20% of Capital Investment 213,000
TOTAL ANNUAL POLLUTION CONTROL 438,100
Unit Cost ($/ton of glass) 6.00
39
-------
TABLE IV-10
STACK GAS FLOW RATES
(Basis: 200 tpd of glass)
Natural Direct
Location Gas Coal
Exit of Furnace Combustion
Gases (scfm) 10,900 12,5002
Melt-off Gases (scfm) 400 400
Total (scfm) 11,300 12,900
Exit from Scrubber
- added water vapor6 (scfm) 5,630 6,430
Total (scfm) 16,930 19,330
Exit from Reheater
- added burner exhaust7 570 660
Total (scfm) 17,500 19,990
Stack Exhaust @ 250°F 23,440 26,660
Coal
Gasification
12.3003
400
12,700
6.330
19,030
650
19,680
26,370
COHOGG
15,600**
400
16,000
7,970
23,970
810
24,780
33,200
Electric
400
400
150
650
20
Particle
Agglomeration
8,800s
400
9,200
1.860
11,060
.370
670
900
11,430
15,310
Btu (hhv)/ton @ 35% excess air; 6.1 x 106 Btu (lhv)/ton
10, Btu (hhv)/ton @ 10% excess air; 6.1 x 106 Btu (lhv)/ton
6.8 x 10fi Btu - Higher heating value (hhv)/ton @ 10% excess air; 6.1 x 10 Btu - Lower heating value (lhv)/ton
6.4 x
6.6 x
8.0 x 10g Btu (hhv)/ton @ 35% excess air and
5.5 x 10 Btu (hhv)/ton @ 10% excess air;
6 Required to cool gas from 1300°F exhaust temp.
7 Exhaust temp, is 800°F
8 Exhaust temp, is 600°F
9 Required to heat to 250°F
efficiency; 6.1 x 10 Btu (lhv)/ton at furnace
to 120°F
-------
TABLE IV,-11
AIR POLLUTION CONTROL COSTS FOR GLASS MELTING FURNACE
(Basis: 200 tpd of glass)
Heat Source
Total Capital Cost ($000)
Annual Operating Cost
($000/yr)
Direct Costs
Labor (plus supervision & overhead)
@ $9.25/hr
Maintenance @ 5% of capital
Utilities
- Electric Power @ $0.0205/kWh
- Fuel @ $2.06/106 Btu
- Water <§ $0.20/1000 gal
Chemicals @ $56/ton Na.O,
$25/ton lime l
Total Direct Costs ($000/yr)
Indirect Costs
Depreciation, 14 years
Return on Invest. @ 20% of Cap.
Ins. & Taxes @ 2% of Cap.
Total
TOTAL ANNUAL COST ($000/yr)
Unit Cost, $/ton of Glass
Natural Direct
Gas Coal
1,136
1,420
Coal
Gasification
1,231
COHOGG Electric
1,430
304
Particle
Agglomeration
950
40
57
32
48
4
6
187
81
227
23
331
40
71
37
56
5
55
256
101
284
28
413
40
62
35
55
4
6
202
88
246
25
359
40
72
44
68
5
6
235
102
286
29
417
40
15
2
2
1
6
66
22
61
6
89
41
21
31
2
6
101
68
190
19
277
518
7.09
667
9.14
561
7.68
652
8.93
155
2.12
378
5.18
-------
TABLE IV-12
UTILITY REQUIREMENTS FOR AIR POLLUTION CONTROL
(Basis: 200 tpd of glass)
to
Item
Electric Power (10 kWh/yr)
- air pollution
- water pollution
Total Electric Power
Total Fuel (10 Btu/yr)
Natural
Gas
1.56
0.07
1.63
23310
Direct
Coal
1.80
0.21
2.01
26990
Coal
Gasification
1.70
0.07
1.77
26500
(air pollution only)
Total Water (106 gal/yr)
(air pollution only)
19.5
24.5
22.0
(1)
COHOGG
2.18
0.07
2.25
33130
26.5
Particle
Electric Agglomeration
0.97
0.07
1.04
820
3.1
1.02
0.07
1.09
15130
8.2
(1)
Includes scrubber purge, evaporation losses, and also Stretford purge for local gasification alternative.
-------
It is estimated that the wastewater stream from the Stretford unit will
have a flow rate of approximately 1000 gpd and will have the following
composition:
Constituent
Sodium carbonate
Sodium Anthraquinone disulfonate
Sodium meta-vanadate
Sodium citrate
Sodium thiosulfate
Sodium thiocyanate
Concentration
mg/1
4700
700
300
300
6000
6000
Waste Load
Ib/day
39.2
5.8
2.5
2.5
50.0
50.0
Although some of the waste constituents (such as sodium citrate) are
biodegradable, others are only marginally so. Conceivably, biological treat-
ment could be employed, but it is impossible to even speculate on its effec-
tiveness. Because of this uncertainty and the very small volume of the waste
stream, it is believed that contract' disposal would be a more feasible,
dependable alternative to evaluate. In contract disposal, the liquid waste
would be hauled away by tank truck and treated and disposed of in the con-
tractor's own treatment facility.
Contract disposal fees are generally on the order of $0.50 per gallon.
The total annual cost for contract disposal of the Stretford wastewater
stream would be $182,500, or $2.50 per ton of glass.
The treatment of the scrubber purge is the same as the treatment described
for the scrubber purge in the base case. The estimated cost is about $0.64
per ton of glass (Table IV-13).
Therefore, the total wastewater treating cost for this alternative is:
Waste Stream
Furnace scrubber water treating
Stretford purge (by contract @ $0.50/gal)
Total
c. Solid Waste Disposal
Cost ($/Ton of Glass)
0.64
2.50
3.14
The coal ash can contain a wide variety of substances, such as metal
compounds; consequently, its disposal into landfills or redeposition into
coal mines should be carried out in a manner which will, under any possible
conditions, prevent pollution of ground water by leaching.
For the example case, we have assumed a coal ash content of 9.6%, in
which case the coal gasifier will generate approximately 2700 tons of ash
per year. This can be disposed of at a rate of $5.00 per ton, for a total
cost of approximately $13,500, or approximately $0.21 per ton of glass.
The dust from the fabric filter amounts to only" 73 tons per year and can
be lahdfilled with the coal ash at a cost of only $0.01 per ton of glass.
43
-------
TABLE IV-13
WATER POLLUTION CONTROL COSTS FOR GLASS MELTING FURNACE
(Basis: 200 tpd.of glass)
Heat Source
Total Capital Cost ($000)
Direct Operating Costs ($/yr)
Labor (plus supervision & overhead) @ $9.25/hr
Maintenance @ 4% of Capital
Chemicals
Electric Power @ $0.0205/kWh
Sludge Disposal
Total
Natural Gas
(Base Case)
95
Direct
Coal
192
All Others
(Same as Base Case)
95
10,200
3,800
500
1,400
3,200
10,200
7,700
1,600
1,400
20,600
10,200
3,800
500
1,400
3,200
19,100
44,500
19,100
Indirect Costs
Depreciation, 14 years
Insurance & Taxes @ 20% of Capital
Total Water Pollution Control Costs
Return on Investment @ 20% of Capital
TOTAL ANNUAL COST ($/yr)
Unit Cost ($/ton of Glass)
-------
The sulfur removed by the Streford process amounts to only 912 tons per
year. In our opinion, this is not enough to warrant any attempt to market
sulfur as a byproduct. Therefore, this solid waste will be landfilled along
with the others. The cost is less than $5000 per year, or about $0.06 per
ton of glass.
D. DIRECT COAL FIRING
Pulverized coal flames have been used to provide energy in cement
processing and in some metallurgical processing but essentially never have
been used in glass processing. One exception, howeyer, has been reported
and that was by Coors, in Colorado, in which they replaced several of their
gas burners in one furnace with coal burners. Also, Columbine Glass (Miller
and Fogelberg, 1975) has sponsored research concerning coal utilization. In
this study one of the natural gas burners was replaced by a pulverized coal
burner at a location near the bridge wall of the furnace, and was used to
supply about one-twentieth of the total energy requirement of the furnace.
The duration of the trial test was four days.
1. Process Description
To use coal directly in burners a coal storage area is needed as well as
a live coal storage bin, a pulverizer, screens, a feeder, and the pulverized
coal bui-ner(s). A coal storage area capable of storing about one month's
supply appears reasonable. Some means of conveying the lump coal from this
storage area to the pulverizer must be provided. The pulverizer is used to
crush the coal to about 200 mesh screens then would be used to remove large
coal particles, i.e., greater than about 0.02 inch (28 mesh). A separate
conveying system is used to convey the powdered coal to a coal hopper or live
storage bin. From this bin powdered coal is metered and fed to the burner
along with the primary air supply. In the burner a secondary air supply is
also introduced and the coal is burned.
2. Energy Considerations
Direct coal firing has the advantage over the other coal-firing proc-
esses in that it uses all of the heating value of the coal. The other, i.e.,
indirect methods, have about an 80% utilization factor, based upon consumption
of 0.37 ton of coal per ton of glass (Arrandale, 1974a), hence direct coal
firing offers considerable energy savings.
To compare direct coal firing with other forms of energy to melt glass,
we assume that it is technically feasible to convert all of the natural gas
burners in the furnace to direct-coal-fired burners. Also, we assume that
it will require 6.8 x 10*> Btu to melt a ton of glass. Therefore, as noted
earlier, for a coal having a heating value of 11,100 Btu per pound, the
daily coal requirement to the burner will be
6.8 x 106 Btu/ton I 200 tons _ 62 f
11,100 Btu/lb x 2000 Ib/ton X day ~ 62 tons °f
45
-------
3. Economic Considerations
a. Capital Investment
For the direct-coal-fired process, the incremental capital costs are
estimated to be $355,000, or 25% more than the base case. This increased
investment, which also affects taxes and insurance, will have an overall
effect of increasing the melting cost'by $0.49 per ton.
b. Production Costs (Table IV-14)
(1) Raw Materials
The raw materials costs for this process will remain essentially the
same as for the base case.
(2) Energy
On the basis of our operating assumptions, we estimate a decrease in
fuel cost of $7.41 per ton for direct coal firing relative to natural gas
firing.
(3) Labor
We estimate that ail incremental increase in labor and labor-associated
costs will be incurred relative to the base case. This increase, estimated
to be $0.41 per ton, or 15%, results from the need to handle large volumes
of coal.
(4) Maintenance Labor and Supplies
We estimate that an increase in maintenance cost of $0.32 per ton, or
19%, will be"incurred.
(5) Miscellaneous Variable Costs
We estimate that this cost will remain essentially unchanged from the
base case.
Overall, we estimate that direct coal firing will decrease glass melt-
ing cost by $5.50 per ton of glass, or about 7.5% from the base case. Based
upon a selling price of $185 per ton, this decrease in melting cost of $5.50
per ton reflects an overall decrease of nearly 3%.
4. Environmental Considerations
a. Air Pollution
The major difference between the base case and direct coal firing is
that coal is a slightly more difficult fuel to burn and will require a
greater amount of excess air to achieve proper combustion. In addition, coal
46
-------
TABLE IV-14
PRODUCTION COST ESTIMATE: DIRECT COAL FIRING
Product: Soda-lime Container Glass
Doily Capacity: 200 tons
Annual Production:65,700 tons
Location: East North Central
Fixed Investment:$1.760.OOP
VARIABLE COST
Raw Materials & Shipping
• Sand
• Feldspar
• Dolomite
• Limestone
• Soda Ash
Energy
• Coal
• Electricity
Water
• Process
• Cooling
Direct Operating Labor
Direct Supervisory Labor
Maintenance Labor
Maintenance Supplies
Labor Overhead
Miscellaneous Variable Cost
TOTAL VARIABLE COST
FIXED COST
Plant Overhead
Local Taxes & Insurance
Depreciation
TOTAL FIXED COST
TOTAL PRODUCTION COST
RETURN ON INVESTMENT
TOTAL
Units Used In
Costing or
Annual Cost
Basis
Net ton
Net ton
Net ton
Net ton
Net ton
Net ton
kwh
1000 gal
1000 gal
Man-hour
Man-hour
—
—
—
—
$/Unit
20
34
63
20
68
20
0.0205
0.20
0.03
5.03
7.29
Units Consumed
per Ton of
Product
0.758
0.072
0.132
0.116
0.263
0.31
19.0
0.00275
0.275
0.22
0.02
Cost per Ton
of Product ($}
15.16
2.45
8.32
2.32
17.88
6.20
0.39
0.00
0.01
1.11
1.15
1.02
1.02
0.80
1.39
58.22
1.14
0.54
1.91
3.59
61.81
5.36
67.17/ton
47
-------
is a high-sulfur fuel; therefore, sulfur dioxide will be included in the gases
going to the melting furnace scrubber. (Low-sulfur fuel was not considered
a viable alternative, because of its expected unavailability and its high
cost at the plant site.)
The capital cost for the control system for direct coal firing will be
slightly higher than that for the coal gasification alternative because of
the greatly increased S02 scrubbing requirements. On the other hand, direct
coal firing does not require the use of a Stretford process. The capital
and operating costs for controlling this alternative (Table IV-11) are about
the same as the costs of control of the coal gasification alternative except
that a greater chemical cost is required to control the greater amount of
sulfur dioxide resulting from direct coal firing. The unit cost for control-
ing direct coal firing is approximately $9.14/ton of glass; whereas, for the
base case it is $7.09 and for the coal gasification alternative, $7.68.
b. Water Pollution
The purge rate from the glass furnace scrubber is more than three times
the purge rate expected from the other alternatives, primarily because the
concentration of sulfates and sulfites is approximately three times higher.
The unit cost for wastewater treatment is approximately $1.38/ton of glass,
versus $0.64/ton of glass for all of the other alternatives (Table IV-13).
c. Solid Waste Disposal
The solid wastes generated from direct coal firing include the coal ash,
the dust from the fabric filter-, and the sludge from the water treatment
plant, primarily calcium sulfate/sulfite from the S02 scrubbing system. The
cost for sludge disposal is included with the water treatment costs, and the
cost for disposal of the other two solid waste sources is the same as for
the other coal alternatives: i.e., $0.01/ton* for the filter dust and $0.18/
ton* for the coal ash.
E. COAL-FIRED HOT GAS GENERATION
1. Process Description
Wormser Engineering, Inc., of Marblehead, Massachusetts, is conducting a
pilot plant feasibility study on a new direct-combustion system. This system,
called COHOGG (coal-fired hot gas generator) (Wormser, Wormser Engineering),
has the potential to provide a combusted gas at a temperature sufficient to
melt glass. Essentially, COHOGG is a conversion burner that may be substi-
tuted directly for oil or gas burners in furnaces, boilers, and other direct
heating applications. Virtually all coal types are suitable, including both
coking and non-coking types and with high- or low-sulfur coals. If this
process is indeed technically feasible, units will have energy outputs con-
sistent with the energy requirements for glass melting.
*ton of glass
48
-------
The system (Figure IV-7) generates a hot gas by separating char and
volatiles, burning the char, and then mixing its products of combustion with
the volatiles and burning them together. A pneumatic conveying system feeds
powdered coal to a pyrolyzer, along with limestone or a mixture of limestone
and sodium chloride. The coal entering the system is heated, along with the
limestone and air, thereby forming a gaseous product (volatiles) and a solid
(char). These products are then separated, the char going to a char burner,
and the volatiles to an afterburner. From one-third to one-half of the sul-
fur in the coal is expected to come off in the pyrolyzer as hydrogen sulfide
(H2S). The limestone, in turn, reacts with the hydrogen sulfide, producing
water and calcium sulfide (CaS). Unreacted limestone, char and calcium sul-
fide go to the char burner, which is a fluidized-bed combustor, where the
remaining sulfur forms S02- Here the remaining limestone from the pyrolyzer
step reacts with the S02, forming calcium sulfate which leaves the bed along
with the ash from the char. In the fluidized-bed reactor, excess air is
mixed with the combustion air to maintain the temperature of the fluidized
bed at about 1600°F. The gases from burning the char leave the fluidized
bed reactor and are combined with the gaseous products, or volatiles from
the pyrolyzer, and burned along with excess air in the afterburner. The out-
let temperature of the gases leaving the afterburner is 3000°F. A modifica-
tion using steam allows a temperature of 3500°F to be realized.
The intent then would be to "pipe" these hot gases from the COHOGG
system to the glass melting furnace. Out of necessity, the COHOGG system
will have to be reasonably close to the glass melting furnace. Details as to
exactly how to feed and play these hot gases over the glass batch are not
known at this time.
Theoretically, this approach to glass melting appears to be feasible. A
potential drawback of the process, which might also hinder its acceptability
in the glass industry, is the absence of a luminous flame. Some people in
the glass industry believe that a luminous flame is necessary for greater
melting efficiency; others do not. The literature is quite confusing in
this area; conflicting data and views are reported. At glass melting temper-
atures, the crown temperatures seem to be of sufficient magnitude to greatly
reduce, if not eliminate, any beneficial effects in increased melting
efficiencies from a luminous flame.
Practically, because the system is still in a pilot plant debugging
stage, it is unlikely that any glass company would seriously consider adopting
the process within the next 10-15' years.
2. Energy Considerations
As mentioned previously, for purposes of comparison we have used through-
out our .analysis a coal with a fixed heating value, sulfur and moisture
content. In view of the present stage of development of this hot gas approach
to melting glass, no data are yet available as to its energy requirements;
therefore, we use value equivalent to that for natural gas firing, 6.8 x 10"
Btu/ton. To melt glass at a 200 tpd rate, the minimum daily coal require-
ment of the burner will be 61 tons, i.e.:
(200) (6.8 x 106)
11,100 X
-------
Char Cyclone
Limestone
Ul
o
Char
& Limestone
& Co.S
Agglomerating
Fluid-Bed
Combustor
Volatile* (1600F)
Products of
Combustion (3000F)
Afterburner
Combustion
Air
Blower
Warm Products
of Combustion
With Excess Air
Ash Cyclone
To Boiler or
Furnace
Ash & Spent
Limestone
Figure IV-7^ Flow Chart for Industrial COHOGG
-------
To allow for inefficiencies in the hot gas process, we chose a system con-
suming 77"tons of coal per day, based on our estimate of an overall effi-
ciency of of 80%.
3. Economic Considerations
Because this system is still in the pilot plant debugging stage, a true
cost estimate which involves capital cost for retrofitting present glass
tanks is highly unrealistic. Therefore, we do not consider the costs asso-
ciated with "piping" the hot gases and retrofitting the glass furnaces, but
we do show both capital investment and operating costs for this system as
add-ons to the cost of natural gas-fired, side port, regenerative furnace.
a. Capital Investment
We estimate that the capital costs for coal-fired hot gas generation
will increase by $1,560,000, or 211%, over those of the base case. This
increased investment has an overall effect of increasing the production costs
by $2.16 per ton of glass melted.
b. Production Costs (Table IV-15)
(1) Raw Materials
The raw materials costs for this process are expected to remain essen-
tially unchanged from those of the base case.
(2) Energy
On the basis of our assumptions, we estimate that energy costs for this
process will be identical to the coal gasification process, hence a fuel
cost savings of 43% relative to the base case.
(3) Labor
We have estimated that this coal process will use somewhat less direct
labor and supervisory labor, plant overhead, and payroll overhead than the
coal gasification process. However, an estimated increase of $5.85 per ton
of glass, or 210%, is expected relative to the base case.
(4) Maintenance Labor and Supplies
Because of the increased capital equipment cost associated with the hot
gas generator, an increase estimated at $0.78 per ton of glass will be incurred
relative to the base case, or an increase of 45% in maintenance-associated
COStF.
(5) Miscellaneous Variable Cost
We estimate a 400% increase in this category, which equals $5.37 per ton
of glass. Overall, we estimate that conversion to coal-fired hot gas genera-
tion will increase the glass melting cost by $12.50 per ton, or about 17%,
over the base case.
51
-------
TABLE IV-15
PRODUCTION COST ESTIMATE: COAL-FIRED HOT GAS GENERATION
Product: Soda-lime Container Glass
Daily Capacity: 200 tons
Annual Production: 65,700 tons
Location: East North Central
$1,560.000 plus
Fixed Investment: SI.404.600
VARIABLE COST
Raw Materials & Shipping Costs
• Sand
• Feldspar
• Dolomite
• Limestone
• Soda Ash
Energy
• Purchased Coal
• Electricity
Water
• Process
• Cooling
Direct Operating Labor
Direct ' Supervisory Labor
Maintenance Labor
Maintenance Supplies
Labor Overhead
Miscellaneous Variable Cost
TOTAL VARIABLE COST
FIXED COST
Plant Overhead
Local Taxes & Insurance
Depreciation
TOTAL FIXED COST
TOTAL PRODUCTION COST
RETURN ON INVESTMENT
TOTAL
Units Used in
Costing or
Annual Cost
Basis
Net ton
Net ton
Net ton
Net ton
Net ton
Net ton
fcWh
1000 gal
1000 gal
Man-hour
Man— hour
—
—
—
—
$/Unit
20
34
63
20
68
20
0.0205
0.20
0.03
5.03
7.29
Units Consumed
per Ton of
Product
0.758
0.072
0.132
0.116
0.263
0.38
19
0.00275
0.275
0.70
0.08
Cost per Ton
of Product ($)
15.16
2.45
8.32
2.32
17.88
7.60
0.39
0.00
0.01
3.52
0.58
1.25
1.25
1.87
6.76
69.36
2.67
0.90
3.22
6.79
76.15
9.02
85.17/ton
52
-------
4. Environmental Considerations
a. Air Pollution
The only difference between the coal gasification alternative and that
of heating the glass melting furnace with a hot combustion gas is that the
sulfur control in the latter option is inherent within the process itself
and is not required as a part of the pollution control apparatus. The gas
volumes to the glass furnace are higher with the COHOGG process because of
the efficiency losses inherent in the system. Except for the slight size
difference, however, the pollution control system for the glass melting fur-
nace itself will be the same as for coal gasification (see Section C of this
chapter and Tables IV-11 and IV-12).
b. Wastewater Treatment
The pollutants from the glass melting furnace are the same for this
process as they are for the base case; therefore, the wastewater treatment
costs will be the same, i.e., $0.64/ton of glass (Table IV-13).
c. Solid Waste Disposal
In addition to the ash from the coal, this alternative has
solid waste stream in the form of calcium sulfate, approximately 40 Ib/ton
of glass, or 1460 tons per year. The corresponding disposal cost at $5.00/
ton is approximately $7300, or $0.10/ton of glass. Hence, the total solid
waste disposal cost for this alternative is approximately $0.29/ton of glass
F. ALL ELECTRIC MELTING
Electric melting of glass has greatly expanded over the past 25 years.
About half of the container glass manufacturers in the United States have
electric boosters, and at least 100 all-electric furnaces, ranging in size
from 4 to 140 tpd, are in operation through the world (Penberthy, 1974).
1. Process Description*
Molten glass can be heated by the passage of an electric current. Both
the design and the operation of an all-electric glass melting furnace differ
greatly from the typical natural gas-fired regenerative furnace. The elec-
tric furnace, without its regenerative checker structure, is a-much simpler
design. Electric furnaces may be classified as either "hot top" or "cold
top." The "hot top" furnace is really an electric furnace with gas boost-
ing, which may be referred to as a mixed-melt furnace. The "cold top"
furnace is the type of design used in all-electric melting. In this design,
after heat-up (by gas or oil) the superstructure is completely or partially
removed.
*(Penberthy, 1974; Loesel, 1975)
53
-------
The most common type of "cold top" has one end wall of the superstructure
removed for charging by a conveyor. The batch layer covering the melter is
continuously renewed by the feeding on of fresh batch over the whole surface.
The raw materials are conveyed, or charged, so that as the batch is progres-
sively covered by successive layers, it heats up gradually, thereby allowing
the glass melting reaction to occur in sequence. This is quite unlike a
fuel-fired furnace, where the batch is subjected to a high temperature upon
its introduction to the furnace. The gas emitted from an electric glass
melting furnace consists almost entirely of water vapor and carbon dioxide.
Control of the batch blanket is critical to the operation of the all-
electric melter. Usually a 3- to 6-inch blanket is maintained. Inadequate
control of the blanket may lead to bridging or blow holes. Bridging occurs
when a semi-hard crust forms out to the side walls. This causes the molten
glass level to decrease, thereby forming a pocket of trapped gases. The
level will continue to decrease until the crust is broken. Sometimes fore-
hearths have been drained before this condition was noted. Blow holes are
formed due to hot spots or areas in the molten glass batch blanket. In these
areas the glass has a lower resistivity; therefore, it develops greater cur-
rent densities, which in turn produce a still hotter area. If not controlled,
a runaway condition could occur, causing damage to the refractories and
possibly a furnace failure.
The latest all-electric glass melting furnaces use vertically positioned
molybdenum rod electrodes. The rods are held in place by water-cooled holders
whose main function is to freeze the glass in place around the electrode so
that it will not be pushed out by pressure and to reduce the surface tempera-
ture of the molybdenum to minimize oxidation. The water-cooled holder for each
rod electrode is built into the refractory floor of the furnace, which is
itself raised above the floor level in the vicinity of the electrodes. This
patented arrangement permits construction of deeper furnaces than is possible
with horizontal electrodes. It also permits the depth of the batch crust
covering the surface of the melt to be controlled by raising or lowering the
electrodes to the height required. Thus the crust of cold raw materials on
the surface of the melt can be maintained as an additional insulation while
its actual thickness can be controlled to meet specific requirements.
At the same time, the paired electrodes can be located in a horizontal
plane to ensure that each is adequately remote from the refractory side
walls of the melting chamber. If the electric energy introduced from the
electrodes into the melt can be largely contained within the confines of the
electrode configurations, the molten glass outside the configurations acts
as a first layer of thermal insulation to the melt. More important, being
relatively viscous by comparison with the molten glass within the electrode
configuration, it acts as a protection to the refractory lining. The advan-
tage of vertical rod electrodes has been borne out in practice and, not only
has the erosion of the refractory lining been considerably reduced with a
comparative increase in campaign life, but the absorption of molybdenum into
the glass has also decreased.
54
-------
2. Energy Considerations
In both the opened and closed "cold top" furnace, the batch blanket
thickness is important in conserving energy and in minimizing emissions. A
thick blanket insulates better and retains more of the radiant heat deeper
in the blanket, hence uses less energy. However, as mentioned above, too
thick a blanket can lead to bridging.
The efficiency of electrically melting glass has been argued about for
years. Electric furnaces are known to utilize 65-80% of the direct heating
energy, compared to 15-20% efficiency for natural gas-fired furnaces. The
power consumption in a large all-electric furnace melting soda-lime container
glass is expected to be about 780 kWh per ton. This figure will vary some-
what according to the percentage of cullet used in the batch, maintenance
and thickness of the batch cover, method of batch charging, and the age of
the furnace and how well it is insulated. In comparing the electrical power
consumption requirements to melt glass electrically versus natural gas firing,
consideration should also be given to the efficiency factor for generating
and transmitting electrical power. Hence, at 780 kWh per ton on an equiva-
lent Btu or fossil-fuel basis, this would be
780 x 10,500 = 8.19 x 106 Btu/ton,
which is actually 20 percent more Btu per ton than used for glass melted in a
natural gas-fired, side port, regenerative furnace.
3. Economic Considerations
a. Capital Investment
For furnaces having no pollution control equipment, we have estimated
that capital costs for an all electric furnace will be about 15% higher,
$219,400, than for a natural gas-fired, side port, regenerator furnace. The
added capital cost for pollution equipment and its installation (discussed
in a separate section of this report) on an electric glass melting furnace
will directly increase the production cost by $0.30 per ton.
b. Production Costs (Table IV-16)
(1) Raw Materials
The cost of the major ingredients in the glass batch for electric melt-
ing will remain essentially unchanged relative to those for the base case.
(2) Energy
On the basis of our operating assumptions and assumed fuel costs, we
estimate that the energy cost entailed in using electrical energy to melt
glass will be greater than that with natural gas. This increase is predicated
55
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TABLE IV-16
PRODUCTION COST ESTIMATE: ALL-ELECTRIC MELTING
Product: Soda-lime Container Glass
Daily Capacity: 200 tons
Annual Production; 65.700 tons
Location: East North Central
Fixed Investment: SI.624.000
•ARIABLE COST
Raw Materials & Shipping
• Sand
• Feldspar
• Dolomite
• Limestone
• Soda Ash
Energy
• Electricity
Water
• Process
• Cooling
Direct Operating Labor
Direct Supervisory. Labor
Maintenance Labor
Maintenance Supplies
Labor Overhead
Miscellaneous Variable Cost
TOTAL VARIABLE COST
FIXED COST
Plant Overhead
Local Taxes & Insurance
Depreciation
TOTAL FIXED COST
TOTAL PRODUCTION COST
BETDKN OH INVESTMENT
TOTAL
Units Used in
Costing or
Annual Cost
Basis
Net ton
Net ton
Net ton
Net ton
Net ton
kWh
1000 gal
1000 gal
Man-hour
Man-hour
—
—
—
—
$/Unit
20
34
63
20
68
0.0205
0.20
0.03
5.03
7.29
Units Consumed
per Ton of
Product
0.758
0.072
0.132
0.116
0.263
780
0.00275
0.275
0.21
0.02
Cost per Ton
of Product ($)
15.16
2.45
8.32
2.32
17.88
15.99
0.00
0.01
1.06
0.15
1.24
1.24
0.86
0.91
67.59
1.23
0.49
1.77
3.49
71.08
4.94
76.02/ton
56
-------
on an increase in the cost of natural gas to $2.06 per 1000 ft-* and a. cost
of electric power of $0.0205 per kWh. Also, if one considers efficiencies in
generating electric power and losses in transmission, on a Btu basis, it takes
more energy to melt glass electrically than it does by natural gas firing.
We have estimated an additional energy cost of $1.60 per ton, or 31%, to melt
glass electrically than with natural gas.
(3) Labor
We estimate that there will be only an incremental increase in direct
labor and its associated costs. We estimate tha.t direct labor will increase
by about $0.10 per ton, which in turn causes an overall labor associated cost
increase of $0.51 per ton, or 18%, relative to the base case.
(4) Maintenance Labor and Supplies
Maintenance costs are expected to increase somewhat, primarily because
of- the cost associated with the electrodes. We estimate that the annual cost
will be about 10% of the melter cost, or $2.47 per ton, versus 6% for the
natural gas case. This is $0.75 per ton, or a 44% higher maintenance cost
than the base case.
(5) Miscellaneous Variable Costs
The costs associated with this category will be somewhat lower for elec-
tric melting than for the base case because low vaporization losses reduce
the cost of many of the minor batch ingredients. Hence, we estimate this
cost at 2% of the raw materials cost, versus 3% for the base case, for a
decrease of $0.47 per ton of glass.
4. Environmental Considerations
a. Air Pollution
The option to electrically heat glass melting furnaces results in a
shift in the environmental problems from the furnace to the electric power
plant. In this case, the only exhaust from the glass melting furnace is
from the decomposition of carbonates, sulfates, nitrates, etc., in the glass
batch. The exhaust will be almost entirely C02, with approximately 3 Ib of
S02/ton of glass.
The control system for this exhaust is identical to the one used for
the base case and for coal gasification, but the size of the system is con-
siderably less because of the greatly reduced exhaust volume. The unit cost
of control for this alternative is only $2.12/ton of glass, versus $7.09
required to control the base case (Table IV-11). However, there is a con-
trol cost associated with the power plant which should be considered. At
present, S02 scrubbing systems cost about $100/kW. Since a 200 tpd glass
melting furnace requires 6500 kWh/hr, the prorated share of control costs
57
-------
which should be allocated to the glass furnace is about $650,000, or about
half of <-^° cost of controls for the other .alternatives. Likewise, the
annual cost of SO? scrubbers is about $0.0033/kWh. Hence, the prorated
share of annual costs allocated to the glass furnace would be about $2.57/ton
of glass, which is also considerably less than the annual control cost of
other alternatives.
b. Wastewater Treatment
The wastewater treatment costs for this alternative are identical to
those discussed in the base case (Table IV-13). Note that even though the
scrubber gas volume is drastically reduced, the amount of pollutants, such
as S02» is about the same since these depend upon the composition of the
glass batch. The scrubber purge depends upon the amount of these pollutants;
and, therefore, the wastewater purge from the scrubber is the same in both
cases.
c. Solid Waste Disposal
This alternative generates solid wastes in the form of dust from the
fabric filter and coal ash (at the power plant). The dust is the same amount
as generated in the base case and the cost of disposal is about $0.01/ton of
glass. The coal ash is about the same amount as for the other coal alterna-
tives. The cost of disposal is estimated to be about $0.18/ton of glass.
G. BATCH AGGLOMERATION - PREHEATING
In this country and in Europe a form of batch preheating has been used,
but only on a laboratory scale. The intent of preheating was to prereact the
batch ingredients, rather than preheating to conserve energy. Relative to
energy conservation, Battelle (Schorr, Battelle) has proposed a combination
of batch pelletizing and preheating of these pellets by utilization of the
waste gases. To our knowledge there are insufficient economic data on large-
scale preheating; therefore, only a preliminary engineering cost estimate
can be made at this time.
1. Process Description
This approach to energy conservation is not yet commercially viable, and
because of the stage of development, processing details are not available
(Figure IV-8). It consists of a number of storage bins, each having its own
weigh hopper and scale. The raw materials are weighed individually, fed to
a collecting belt, and conveyed to a mixer. A pan mixer, or muller, is used
to blend the dry powders. Up to this stage the process is identical, or can
be identical, to the present processing techniques used by each of the glass
manufacturers; after mixing, the processes begin to differ. From the mixer,
the blended batch would have to be transferred or conveyed to a surge hopper
and weigh feed. Material would then be fed to a pelletizer, where it may be
necessary to add water, about four percent by weight, as a binder for the
pellets. The pelletized material would next be conveyed through a "high-
temperature" continuous dryer which would be heated by the waste gases of
58
-------
I I I I I
Individual Weigh Hopper
Collection Belt
, J Mixer
Surge Hopper & Feeder
©
Pelletizer
Waste Heat Heater
Hot Feed Conveying System
Q_
Figure IV-8. General Schematic of Batch Agglomeration - Preheating
59
-------
the glass melting furnace. Before being fed into the glass tank, the pellets
would be heated to about 1290°F, or possibly higher. Although, the process-
ing steps appear quite simple, the details of how to transfer and feed the
heated pellets require a great deal of development work.
2. Energy Considerations
It is expected that batch agglomeration-preheating will have a marked
beneficial effect in terms of energy consumption in glass melting. As men-
tioned elsewhere, about one-third of the energy required to melt glass, or
about 2.3 x 10^ Btu per ton, is used to heat the raw materials to their melt-
ing temperature. Therefore, if the raw materials are heated by the waste
gases from the furnace to about the 1290°F temperature range, this would
correspond to an energy savings of more than 1 x 10^ Btu per ton, or about
20%. Battelle has estimated energy savings of 25%; however, this means that
the batch would have to be preheated to upwards of 1500°F; and at these tem-
peratures, the problems of handling the material become severely compounded
by the fact that it is becoming a sticky solid.
3. Economic Considerations
a. Capital Investment
An increase in capital investment of $500,000 is estimated to be required
to purchase and install the additional equipment necessary to pelletize and
preheat the batch ingredients. This translates to an overall capital cost
increase of $0.68 per ton to melt glass relative to the base case.
b. Production Cost (Table IV-17)
(1) Raw Materials
We do not foresee any significant changes in raw materials costs between
this and the base case.
(2) Energy
On the basis of our assumptions, we estimate an energy cost decrease of
$1.20 per ton.
(3) Labor
It is expected that an incremental addition of direct labor will be asso-
ciated with this manufacturing modification. We estimate that direct labor
will increase by $0.15 per ton, which then is reflected by an overall increase
of $0.41 per ton, or 15%, when the other components of labor are factored
into the production cost.
60
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TABLE IV-17
PRODUCTION COST ESTIMATE: NATURAL-GAS-FIRED;
BATCH AGGLOMERATION-PREHEATING, SIDE PORT, REGENERATIVE FURNACE
Product: Soda-lime Container Glass
Daily Capacity: 200 tons
Annual Production: 65.700 tons
Location: East North Central
Fixed Investment: $1.905.000
VARIABLE COST
Raw Materials & Shipping
• Sand
• Feldspar
• Dolomite
• Limestone
• Soda Ash
Energy
• Purchased Gas
• Electricity
Hater
• Process
• Cooling
Direct Operating Labor
Direct Supervisory Labor
Maintenance Labor
Maintenance Supplies
Labor Overhead
Miscellaneous Variable Cost
TOTAL VARIABLE COST
FIXED COST
Plant Overhead
Local Taxes & Insurance
Depreciation
TOTAL FIXED COST
TOTAL PRODUCTION COST
RETURN ON INVESTMENT
TOTAL"
Units Used in
. Costing or
Annual Cost
Basis
Net ton
Net ton
Net ton
Net ton
Net ton
106 Btu
kWh
1000 gal
1000 gal
Man-hour
Man-hour
*•
$/Unit
20
34
63
20
68
2.06
0.0205
0.20
0.03
5.03
7.29
Units Consumed
per Ton of
Product
0.758
0.072
0.132
0.116
0.263
5.5
19.0
0.00275
0.275
0.22
0.02
Cost per Ton
of Product ($)
15.15
2.45
8.32
2.32
17.88
11.34
0.39
0.00
0.01
1.11
0.15
1.02
1.02
0.80
1.38
57.13
1.14
0.58
2.07
3.79
67.14
5.80
72.94/ton
61
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(4) Maintenance Labor and Supplies
It is estimated that an additional maintenance cost of $0.31 per ton, or
17%, will be incurred relative to the base case.
(5) Miscellaneous Variable Costs
For this category, we estimate that there will be no significant change.
At, a natural gas.cost of $0.93 per 10 Btu, batch agglomeration-preheating
has essentially the same overall cost as the base case; however, as the cost
of natural gas increases, so will the potential savings of this process.
4. Environmental Considerations
a. Air Pollution
The batch preheat technology is an energy conservation technology relat-
ing to a furnace modification rather than a method of furnace heating. Hence,
this technology is applicable to all of the previously discussed methods of
heating (except for electric heating). By improving the thermal efficiency
of the furnace, this technology reduces the fuel requirement per ton of glass,
thereby reducing the exhaust volume from the glass melting furnace. The
reduction in gas volume to the control system correspondingly reduces control
costs.
The types of controls used for batch preheating are identical to those
described previously for the base case, but the system is smaller because of
the increased thermal efficiency of the furnace. The cost of control for
this alternative is considerably less than that for other alternatives using
coal, and it is approximately the same as the control cost for electric
power if the allocated costs for power plant control are included in the cost
of control of the glass furnace (Table IV-11).
b. Wastewater Treatment
Even though the gas volume from the scrubber is reduced, the wastewater
treatment associated with this alternative is identical to that of the other
alternatives because the amount of pollutants, primarily SC^, is the same in
all cases (resulting from the decomposition of materials in the glass batch).
The costs for water treating (Table IV-13) have been assumed to be identical
with the costs for the base case.
c. Solid Waste Disposal
The costs for solid waste disposal for this alternative depend upon the
fuel being used for the furnace. Using natural gas, the costs are the same
as the costs for the base case, i.e., l£/ton of glass. Using coal, an addi-
tional cost of approximately 18e/ton of glass is required for disposal of the
coal ash.
62
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V. IMPLICATIONS OF POTENTIAL PROCESS CHANGES
A. COAL GASIFICATION
1. Impact On Pollution Control/Energy Requirements
In this analysis we assume that the basic glass melting function is
similar to present operations using natural gas as the energy form. Although
the experience in the industry has been that changes in the energy form do,
in fact, change operation conditions, the basic process remains without
major alterations.
The primary process modification of the base case (natural-gas-fired,
side port, regenerative furnace) is the addition of on-site facilities to
produce low-Btu gas through the controlled combustion of bituminous coal.
This requires additional capital outlays as well as additional operating
cost for the gas producer.
In addition, the composition of the emissions from the glass melting
furnace, principally from the high-temperature combustion and the decompo-
sition of the batch, are not expected to be altered; however, higher gas
volume will result in higher volume of emission. No additional water
effluent streams are created at the glass furnace. The gasification
facility itself introduces two new effluent streams: the solid waste stream
in the form of ash from the combustion process; and the water purge from the
sulfur recovery system on the existing gas stream. The recovery system is
essential to remove I^S from the gas before it enters the glass melting
furnace, thereby reducing the load on the furnace scrubbing system.
The sulfur from the recovery system and the ash from the combustion
process are assumed to be taken to landfill. The water stream from the
sulfur recovery system is estimated to be about 1000 gpd and it is antici-
pated that contract disposal would be most feasible. The capital cost and
annual operating cost associated with the pollution control system are sum-
marized in Table II-2 (which is reproduced here as Table V-l).
Because of the higher gas volumes required due to the additional com-
bustion- air requirements, an increase in the capacity of the air emission
control system on the glass melting furnace is needed. The increase of
about -3000 scf of gas results in an increased pollution control capital
cost of $97,000 and operating cost of $0.59/ton of glass.
63
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TABLE V-l
SUMMARY OF INVESTMENT AND OPERATING COST FOR THE BASE CASE* AND ALTERNATIVE
FUEL SYSTEM AND PROCESS MODIFICATIONS
Water
Melting Unit Process
Natural Gas Firing
Investment ($000)
Operating Cost***$/ton
Coal Gasification
Investment ($000)
Operating Cost $/ton
Direct Coal Firing
Investment ($000)
Operating Cost $/ton
Coal-Fired Hot Gas Generation
Investment ($000)
Operating Cost $/ton
Electric Melting
Investment ($000)
Operating Cost $/ton
Batch Preheat with/Natural Gas Firing
Investment ($000)
Operating Cost $/ton
Facilities
Glass Auxiliary
Furnace Installation
1,404
72.67 ' —
1,404 1,380
91.74
1,404 355
67.17
1,404 1,560
85.17
1,624
76.02
1,404 500
72.94
Air Pollution Control
Glass Auxiliary
Furnace Installation
1,136
7.09
1,231 1,066
7.68 6.00
1,420
9.14
1,420
8.93
304 (650)**
2.12 (2.57)**
951
5.18
Pollution Control
Glass Auxiliary
Furnace Installation
- 95
0.64
95
0.64 2.50
192
1.38
95
0.64
95
0.64
95
0.64
Solid Waste Control
Glass Auxiliary
Furnace Installation
0.01
6.01 0.24
0.01 0.21
0.01 0.28
0.01 (0.18)**
0.01
Total
2,635
80.41
5,176
114.81
3,371
77.91
4,479
95.03
2,673
81.54
2,950
78.77
*Base Case - 200-tpd, Natural- Gas-Fired, Side Port, Regenerative Furnace. Costs Reflect only Melting Cost.
**Cost of pollution control at power generation station prorated to glass plant.
***0perating cost $/ton = production cost plus pre tax return on investment @ 20%.
-------
The energy use implication of replacing natural gas with gas from coal
gasification is principally one of replacing a low-availability fuel with a
less critical and available fuel, i.e., coal. It is anticipated that energy
consumption required to melt the glass would remain the same as in the case
of natural gas and experience (Tooley, 1974) indicates that a consumption of
0.37 ton of coal per ton of glass is realistic and conservative.
.2. Factors Affecting Probability of Change
By far the principal implication for the glass industry is the very
significant investment required to build the coal gasification facility.
The estimated additional investment of $1.4 million is approximately 12.5%
of the estimated total plant investment for a 200-tpd operation. If the
further cost of pollution control equipment is considered, the additional
annual cost resulting from melting glass using coal gasification is esti-
mated to be $34.40 per ton of glass, an increase of 43%.
This is a substantial increase and would place products like glass
containers at a disadvantage to aluminum and steel in the large beverage
market. If such costs are not recovered through price increases, the effect
on profitability would be large and could affect the viability of a large
fraction of the industry.
With these economic factors, it is unlikely that the glass industry
will voluntarily move in the direction of coal gasification as an alterna-
• tive to natural gas.
3. Areas of Research
Since the economic viability of melting glass with gas produced by coal
gasification is questionable, further work on the treatment of effluent
streams from the gasification process is not warranted. However, as there
is presently no proven process for the treatment of the emissions from the
glass melting furnace, this area would be a more fruitful one for research.
The specific problem of treatment of the emissions from the glass furnace
are detailed in the base case environmental consideration section of this
report.
B. DIRECT COAL FIRING
1. Impact On Pollution Control/Energy Requirements
In terms of energy conservation, direct firing of glass furnaces with
pulverized coal is a utilizaton of a less critical form of fuel than present
natural gas processes. Furthermore, direct firing of coal is a more effi-
cient utilization of the heating value of the coal compared with coal gasi-
fication and hot gas generation.
65
-------
The pollution control implications of direct firing with pulverized
coal are mainly the increased gas volume in the glass tank and the addi-
tional air emission as a result of the S0£ and ash generated in the com-
bustion process. The increased stack gas flow rates (13-14% greater than
in natural gas firing) substantially add to the pollution control cost,
making these costs for direct coal firing the highest*of all the alternatives
considered.
2. Factors Affecting Probability of Change
The technical feasibility of direct firing of the glass melting func-
tion with pulverized coal has not been determined. There are two technical
areas where problems are anticipated. First, the effect of the ash on the
life of the refractories due to the fluxing action of the fly ash could
substantially reduce the furnace life; second, reactions between- the ash and
the refractories may result in excess stones, seeds, etc., in the finished
product. No doubt, if this alternative were used, furnace design and
operation would have to be altered considerably.
The consistency of coal in terms of heating value, ash content and
sulfur would be a major consideration because variable coal feed would make
furnace operation difficult and influence the pollution control characteristics.
From an economic standpoint, direct coal-fired furnaces are competitive
with natural gas furnaces and appear to be less expensive than coal gasifi-
cation, coal-fired hot gas generation, and electric melting. The additional
capital cost for coal storage, handling, pulverizing and feed is modest;
however, the glass furnace would entail additional costs for pollution
control.
3. Areas of Research
The feasibility of direct coal-fired glass melting furnaces has not
been satisfactorily demonstrated. Whether the entire furnace can be con-
verted to direct coal firing or whether only a portion of the melting is
done with coal is questionable because the adverse effect on glass quality
is still unanswered.
C. COAL-FIRED HOT GAS GENERATION
1. Impact On Pollution Control/Energy Requirements
The approach to replacing natural gas with a modification of a coal-
related process of this nature has not been reduced to practice. The
system is in an early stage of development and scaled pilot systems are
only now being considered. Obviously, there are little data upon which to
draw conclusions as to the viability of this approach as an alternative in
glass melting.
66
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In this process the hot (3000°F) gas is generated by separating the char
and volatiles, burning the char, and recombining the products of combustion
and burning them together. The principal emission stream generated in this
on-site facility is the ash and spent limestone from the fluidized-bed com-
bustor. There appears to be no water or air emission from the generator.
The cost of solid waste removal is estimated to be $0.29/ton of glass.
It is visualized that with some changes to permit the gas to be intro-
duced under control the hot gas can be used in a typical side port, regenera-
tive glass furnace. Because of the increased gas volume involved due to the
efficiency of the system, there is some increase in the air pollution con-
trol requirement for the furnace glass tank. It is anticipated that no
changes in type or composition of the particulate or gas emissions from the
glass batch will take place. The cost of air pollution control using the
coal-fired hot gas generator is estimated to be $8.93/ton versus $7.09/ton
of glass in the base case.
No additional water effluent streams are associated with the hot gas
generator nor are there any further requirements for process water at the
glass melting furnace.
We assume that the energy requirement for melting glass is 6.8 x 10^ Btu/
ton, and 0.37/ton of coal with a heating value of 11,100 Btu/lb will be
required to melt a ton of glass. Energy conservation is implied in that the
hot gas generation process uses a less critical fuel, coal, to replace a
critical one, natural gas.
2. Factors Affecting Probability of Change
The most important questions are the reliability of a scaled
system of the size required for glass melting, and the adaptability of this
technique to the melting of glass. The importance of a luminescent flame in
the melting process is not clear and there is no doubt that furnace design
modifications would be required and operating practice would be altered.
Estimates of the capital investment indicate that the cost of
$1.56 million to provide an on-site facility essentially equal the cost of
the glass melting furnace (without pollution control equipment). The hot
gas generator does not add significantly to the cost of pollution control;
however, the larger gas volumes at the glass melting furnace increase the
size of the air emission control system. This fuel form results in an over-
all increase in operating cost of $14.62/ton, or 18%, relative to the base
case.
3. Areas of Research
At this time, the adaptation of the coal-fired hot gas generator to the
glass melting process is questionable. The potential that this alternative
has to replace the conventional natural gas process can only be determined
from more extensive operating information and development works. It is esti-
mated that this alternative can be considered for the very long term.
67
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The process does not introduce any new areas that would require
research on control of the effluent streams.
D. ELECTRIC MELTING
1. Impact On Pollution Control/Energy Requirements
Although -the size of present-day furnaces is small, electric melting of
glass is being done. The melting process using electricity is significantly
different from that using fossil fuels. In electric melting the heat is
generated directly in the glass melt itself rather than the heat being applied
above the melt and relying on radiation as the principal heat transfer
mechanism. The cold top implies that the top of the glass mel-t is covered
by the raw batch, thus reducing the high heat losses from the hot melt.
.Melting of the batch takes place at the melt-batch interface.
The pollution implications of cold top electric melting have been clear
for some time. Since no combustion takes place in the air atmosphere above
the melt, NOX is not created, and any possibility of SOX from fossil fuel is
also eliminated. Although decomposition of the batch ingredients, such as
sulfates, nitrates, carbonates, etc., will still be a source of air emission,
dusting due to the entrainment of batch ingredients in the high-velocity
flames of fossil fuel-fired tanks is eliminated. Electric melting does not
introduce any additional water effluent streams.
Basically, the volume of gaseous emissions from an electric melting
furnace is only a fraction (~4%) of the emissions from a similar fossil
fuel-fired furnace. Therefore, the likely requirements for air emission
controls on a 200-tpd electric furnace are $304,000, versus $1,136,000 for
a natural gas-fired furnace.
The cost of electric melting appears to be comparable to that of a
natural gas-fired furnace. Electric melting costs are estimated to be less
than those associated with other forms of energy, such as coal gasification
and coal-fired hot gas generation.
By using the alternative of electric melting, a more available form of
energy replaces a less available one and this can be considered a form of
energy conservation. No overall reduction in the environmental problem and
control is anticipated, since this approach essentially shifts the environ-
mental problems and pollution control from the glass furnace to the electric
power station. In the cost comparison a portion, of the environmental con-
trol cost at the power plant was prorated and assigned as a cost of electric
melting. , ,
2. Factors Affecting Probability of Change
One of the major factors that would inhibit the glass industry's
broad adoption of electric melting is the availability of sufficient power
generating capacity in areas where glass is manufactured. The high capital
investment required and the lack of capital at reasonable cost has inhibited
the expansion of electric power generation capacity.
68
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Another major hurdle is the feasibility of construction of large
(>200-tpd) electric furnaces; present-day furnaces are of the order of
100 tpd. Before one can predict the possibility of electric melting in
large plants producing flat glass or containers, considerably more infor-
mation and experience is required.
3. Areas of Research
The feasibility of developing electric glass melting furnaces of larger
than present electric melters needs to be studied. The development of a
"proven air emission control" system for the lower emission values of this
type furnace would be highly desirable.
E. BATCH PREHEATING
1. Impact On Pollution Control/Energy Requirements
The alternative of batch preheating is somewhat different than the other
approaches since the fuel form does not change. Instead, this approach uses
heat from the melting process to preheat the batch ingredients to some frac-
tion of the glass melt temperature. It is estimated that a preheat tempera-
ture of 1300°F would reduce the energy consumption in the furnace by about
20%. In a sense, batch preheating could be used with all of the alterna-
tive approaches to melting glass that we have reviewed except electric
melting.
The pollution control implications in batch preheating are the signi-
ficantly lower stack gas flow rates and, consequently, smaller volumes of
air effluent to handle, thus significantly reducing the cost of control.
The batch preheat process produces no additional water streams. As a
result, the additional cost due to pollution control is $5.83/ton of glass,
about 25% less than control costs for the base case.
2. Factors Affecting the Probability of Change
Utilization of the batch product will require confirmation of the
calculated energy savings. At this time, neither the technical nor economic
feasibility have been demonstrated. It appears as if the capital cost might
be modest; however, this must be confirmed after technical feasibility has
been demonstrated.
Whether existing glass plants could implement the technology, once it
is determined feasible, would depend on specific plant situations. Space
limitations may make it difficult to alter the in-line process.
69
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REFERENCES
Alexander, F., "Why Regenerative Melting," The Glass Industry, p. 12,
May 1974.
Arrandale, Roy S., "Fuels and Fuel Economics," Handbook of Glass Manufacture,
F.A. Tooley (ed.), Books for Industry, New York, 1974b.
Arrandale, Roy S., "Furnaces, Furnace Design and Related Topics," Handbook of
Glass Manufacture, F.V. Tooley (ed.)> Books for Industry, New York, 1974a.
Battelle Laboratories, Final Report on Industrial Energy Study of the Glass
Industry, Cilumbus, Ohio, for EPA, Contract No. 14-01-0001-1667, December, 1974.
Department of Commerce, Bureau of Census, 1972 Census of Manufactures.
Hamilton, J.C., "Applied Research in Glass Melting," Industrial & Chemical
Imdustries, pp. 16-21, February 1970.
Arthur D. Little, Inc., Economic Analysis of Effluent Guidelines - The
Pressed and.Blown Glass Industry, for EPA, Contract No. 68-01-1541, January
1975.
Loesel, R.E., "Practical Data for Electric Melting," The Glass Industry,
p. 16, February 1975.
Miller, K.A. and Fogelberg, C.V., "Pulverized Coal-Air Burners for Glass
Tanks," The Glass Industry, pp. 12-14, March 1975.
Nelson, S., Private Communication, Applied Technology, Inc., Pittsburgh,
Penna.
Penberthy, L., "Electric_Melting of Glass," Handbook of Glass Manufacture,
F.V. Tooley (ed.), Books for Industry, New York, 1974.
4
Schorr, J.R., Private Communication, Battelle Laboratories, Columbus, Ohio.
Tooley, Fay V., "Raw Materials," Handbook of Glass Manufacture, Boqks
for Industry, New York, 1974.
Wormser, Alex, Private Communication, Wormser Engineering, Marblehead, Mass.
70
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APPENDIX A
INDUSTRY STRUCTURE - GLASS MANUFACTURING
1. DESCRIPTION
a. Industry Sectors
The manufacturing of glass and glass products in the United States is a
large, widely diversified industry. The Standard Industrial Classification
(SIC) is a helpful but not exclusive guide for segmenting the glass industry.
The greater portion of manufactured glass products falls under the SIC 3-digit
classifications 321 and 322. However, an important segment of the U.S. glass
industry is the manufacture of glass wool products., which is listed in SIC 3296.
Another consideration in defining the industry segment of highest priority in
this discussion is the relative energy consumption; therefore, those manufac-
turing processes involved in producing products from purchased glass and
those that require relatively minor quantities of energy are of less interest.
To effectively examine the energy-intensive, large-volume production of
glass, we have viewed the industry more in terms of its structure than its
SIC numbers. Thus, the segments of the industry have distinct products, sell
into different markets, have different technology, and involve specific
companies.
The segments of the glass industry covered in this discussion are:
Flat Glass - (SIC 3211) including sheet, plate and float, laminated,
tempered automobile glass
Glass Containers - (SIC 3221) food, beverage, pharmaceutical glass
-------
b. Flat Glass Segment*
The production of sheet, plate and float glass in the United States is
highly concentrated and involves only seven companies (Table A-l). More than
87% of the U.S. output of sheet glass is produced by PPG Industries (PPG),
Ford Motor Company, Libby-Owens-Ford (LOF), and ASG Industries (ASG). These
four companies plus Guardian Industries and C-E Glass (a subsidiary of Com-
bustion Engineering) are the only producers of float glass.
In summary, three firms largely dominate U.S. production of plate glass.
Two, PPG and LOF, are large, multiproduct firms producing a wide range of flat
glass products, including rolled and tempered as well as other industrial pro-
ducts. They also participate in the foreign production of flat glass through
arrangements ranging from process licensing agreements and joint ownership of
foreign facilities. The third major company, Ford, produces float and tem-
pered glass primarily for its own vehicles, but also for sale to the trade.
Two smaller firms, ASG and Fourco Glass Company, also are fairly signi-
ficant. ASG produces sheet, float and rolled glass (as well as tempered
architectural glass); Fourco's production is limited to sheet glass. Finally,
Guardian, while a substantial processor of laminated and tempered automotive
glass, only commenced the production of float glass in 1970; C-E Glass did
so only as recently as 1971.
In addition to Guardian Industries, Ford, LOF, and PPG are manufacturers
of raw glass as well as fabricators of laminated and tempered automotive glass.
These four companies, plus Chrysler, which purchases raw glass and fabricates
it for use in its automobiles, probably account for more than 80% of automo-
tive glass manufactured in the United States; the remainder is produced by
three small independent companies, Shatterproof Glass Corporation, Safelite
Industries, and Safetee. Shatterproof produces both laminated and tempered
glass; the other two companies are only laminators. All three companies
purchase raw glass from the major producers for further processing.
LOF is the largest automotive glass' fabricator, serving along with
PPG, General Motors' needs. Shatterproof, Guardian and other small com-
panies mainly supply the replacement market.
c. Glass Containers**
The glass container industry in the United States is large, employing
more than 70,000 persons and producing products valued at more than $2 billion
in 1972. Its total employment is three times arid the value of its shipments
is nearly four times that of the flat glass industry.
*Arthur D. Little, Inc., 1973.
**Arthur D. Little, Inc., 1975.
72
-------
TABLE A-l
Company
ASG
Combustion Engineering
Chrysler
Ford
Fourco
Guardian
LOF
PPG
Safelite
Safetee
Shatterproof
**
Under construction
Planned 1974
FLAT GLASS COMPANIES .BY TYPE OF PLANT AND LOCATION
Type of Plant
Plate Float
Sheet
Jeanette, Pa.
Okmulgee, Okla.
Kingsport, Tenn. Greenland, Tenn.
^Floreffe, Pa.
Almonesson, N.J.
Dearborn, Mich.
^Nashville, Tenn.
Tulsa, Okla.
Clarksburg, W. Va,
Ft. Smith, Ark.
Charleston, W. Va.
(2)
Rossford, Ohio
Henryetta, Okla.
Mt. Vernon, Ohio
Clarksburg, W. Va.
Mt. Zion, 111.
Fresno, Cal.
Cumberland, Md.
Carleton, Mich.
Toledo, Ohio
Ottawa, 111.
Lathrop, Cal.
^Rossford, Ohio
Laurinberg, N.C.
Cumberland, Md.
Meadville, Pa.
Crystal City, Mo.
^Carlisle, Pa.
Wichita Falls, Tex.
Laminating
Tempering
Detroit, Mich.
Dearborn, Mich.
Detroit, Mich.
Nashville, Tenn.
Detroit, Mich. Millburg, Ohio
Toledo, Ohio
Ottawa, 111.
Lathrop, Cal.
Creighton, Pa.
Greenburg, Pa.
Wichita, Kan.
Enfield, N.C.
Phila., Pa.
Detroit, Mich.
Toledo, Ohio
Ottawa, 111.
Lathrop, Cal.
Rossford, Ohio
Crestline, Ohio
Tipton, Pa.
Carlisle, Pa.
Detroit, Mich.
-------
The glass container manufacturing industry comprises approximately
30 firms operating a total of about 130 plants (Table A-2). However, the
eight largest firms account for two-thirds of the plant locations and about
78% of the total industry shipments.
Nine large firms dominate this business. Among the major firms in this
industry segment is Owens-Illinois, with annual sales in 1972 of $1.6 billion,
of which domestic glass containers account for 62% ($992 million). The com-
pany is a major producer of plastic and paper packaging, technical electronics,
and consumer glassware, paper, and plastic products. It operates 20 glass con-
tainer plants in 14 states and participates in a variety of operations.
Brockway Glass Company produces glass containers, with total sales of
$236 million in 1972. It operates 14 glass container plants in 11 states.
Glass containers constituted 66% ($158 million) of Anchor-Hocking sales
of $240 million in 1972. It operates nine glass plants in eight states.
Other major producers in the glass container industry are Chattanooga
Glass Company, Glass Container Corporation, Kerr Glass Manufacturing Com-
pany, Thatcher Glass and Metro Containers.
Glass container manufacturing plants are spread throughout the country
to service the requirements of regional customers. While these plants are in
virtually every area, they are largely concentrated in the East, North, Cen-
tral and Middle Atlantic states, near industrial centers.
d. Other Pressed and Blown Glass Manufacturing*
According to the SIC, there are more than 50 different product lines in
this segment of the industry. However, the major products in terms of dollar
value and total production volume are household tableware, lamp enclosures,
T.V. bulbs, and glass tubing.
According to the 1972 Census Reports, the total shipments of glass
tubing were $55 million, largely in tubing for fluorescent and neon lighting.
The major producers of glass tubing are very large multiproduct firms, but
these products are not a significant portion of their total business (Table
A-3). Much of the tubing is produced by captive operation, i.e., the tubing
being made into finished products by the same company (General Electric,
Westinghouse, Sylvania). Major companies such as Corning and Owens-Illinois
are leading merchant manufacturers of tubing. These companies are also the
leading producers of scientific glass tubing.
The total shipments for lamp enclosures, including incandescent lamp
envelopes, television tube envelopes, and electronic tub'e parts, was
$253 million in 1972. Of this total, it is estimated that T.V. envelopes
accounted for about two-thirds, electronic tubes for one percent, and
*Arthur D. Little, Inc., 1975.
74
-------
TABLE A-2
GLASS CONTAINER MANUFACTURERS
No. of
Company Plants
Anchor Hocking 9
Arkansas Glass Container 1
Ball Corporation 4
Bartlett Collins, Corp. 1
Brockway Glass Co. 14
Castle-Hanson (Seneca Food
Corp.) 1
Chattanooga Glass Co. 6
Columbia Glass Co. 1
Columbine Glass Co. 1
Diamond Glass 1
Gallo Glass Co. 1
Glass Container Corp. 14
Glenshaw Glass 2
Hillsboro Glass 1
Industrial Glass Co.
(Tropicana) 1
Kerr Glass Mfg. Co. 10
Latchford Glass 1
Indian Head 7
Liberty•Glass 1
Lincoln Container Co. 1
Metro Glass Div.,
(Krattco Corp.) 4
Midland Glass Co. 3
National Bottle Co. 4
National Can Co. 3
Owens-Illinois 20
Thatcher Glass 7
Underwood Glass 2
Wheaton Glass 1
Others not identified 8
Major Products
General line, also tableware
General line
General line
Private mold, also tableware
General line
Food containers
Beverage, food, cosmetics, beer
Cosmetic, chemical, drugs
Beer
Cosmetic, drugs
Wine bottles
General line
Jars, wide and narrow mouth.
Liquor
Jars, narrow and wide mouth
General line
General line
General line, wine
Beverage, milk, juice
Beer, liquor, private mold
Flasks, jars, bottles
Beer, food chemicals, preserves
Liquors, food, chemicals
General line
General line
Flasks, jars, jugs, narrow and
wide mouth
Flasks, jars, jugs, beverage,
narrow and wide mouth
General line
Estimate
Source: Arthur D. Little, Inc., estimates.
-------
Company
Corning Glass Works
Demuth Glass Division
GTE Sylvania
General Electric Company
Owens Illinois
Westinghouse Electric
Wheaton Industries
TABLE A-3
MAJOR GLASS TUBING MANUFACTURERS
Glass Tubing Products
Pyrex brand tubing.
Corning brand products—
fluorescent and thermometer
tubing.
Glass Tubing Plants
Parkersburg, West Virginia
Corning, New York (Fall Brook Plant).
Other plants where tubing is
.not major -product:
Blackburg, Virginia
Danville, Kentucky
Central Falls, Rhode Island
Wellsboro, Pennsylvania
Glass tubing and rod in Parkerburg, West Virginia
bulk, vials, ampoules,
heavy and light wall cylinders,
culture and test tubes, pipettes.
Glass tubing for fluorescent Greenland, New Hampshire
lights.
Glass tubing for fluores-
cent lights.
Glass laboratory ware,
tubes for electronic and
industrial uses.
Glass tubing for fluores-
cent lights.
Laboratory, technical
and votive glassware.
Versailles, Kentucky
Logan, Ohio
Jackson, Mississippi
Bridgeville, Pennsylvania
Bucyrus, Ohio
Kimble Products, Vineland,
New Jersey
Fairmont, West Virginia
Millville, New Jersey
Production (tpd)
7.5
112.0
107.0
97.0
NA
110.0
65.0
44.0
NA
150,000 pieces
-------
incandescent lamps for -33%, or $84 million. Five major companies produce
incandescent lamp enclosures; two of them, Westinghouse and General Electric,
are captive producers (they also manufacture the complete light bulb).
Corning is a merchant producer which sells to manufacturers of light bulbs,
such as Sylvania.
Corning and Owens-Illinois are the principal manufacturers of televi-
sion tubes in the United States. Additional captive capacity exists in the
RCA plant in Circleville, Ohio. Only color funnel and face plates are being
manufactured in the United States in substantial quantities. Corning and
Owens-Illinois are integrated multiproduct glass companies.
e. Fiber Glass*
The U.S. production of textile fiber glass products is dominated by
four firms. Two, Owens-Corning Fiberglass and PPG Industries, account for
about 80% of the total capacity of 750 x 106 Ib/yr. The other two, Johns-
Manville and Certain-Teed, account for approximately 13% of the total.
Five other producers divide the remaining 7%. OCF is principally a fiber
glass producer, manufacturing both textile and wool glass products. PPG is
a large integrated chemical company that produces flat glass as well as
textile fibers. Most of the other firms in this business are divisions of
integrated companies.
Owens-Corning is also the dominant producer of glass wool fiber and with
Johns-Manville has nearly 90% of the U.S. production. The only significant
"additional capacity is that of Certain-Teed in three plants. Since the
economical production of glass wool is a high-volume operation, there are no
small producers in this industry segment. Johns-Manville an4 Certain-Teed
are integrated multiproduct companies. The total U.S. capacity is close to
1.8 x 10* Ib/yr.
2. PLANT CHARACTERISTICS
Because of the diversity in product and type of process used, and con-
sidering the long history of this industry and that of its subsegments, the
industry is difficult to categorize: in some segments the number of plants
is large and plant capacities are not disclosed. Therefore, we use a typical
or average plant to characterize each of the industry's subsegments
(Table A-4).
Flat glass production is usually a high_yolume operation with float
plant capacities reaching 1500 tons/day (Arthur D. Little, Inc., 1973). Both
float and sheet are continuous operations and have production speed of 225-
400 ft/hr for sheet production and up to 1500 ft/hr for float plants. Yields
are usually a little higher in sheet operations but float processing is more
economical. Laminating and tempering operations are most often separated from
*Arthur D. Little, Inc., 1972.
77
-------
00
TABLE A-4
TYPICAL PLANT CHARACTERISTICS
Industry Segment
Flat Glass
Float
Sheet
Laminated
Tempered
Glass Container
Pressed & Blown
Tubing
T.V.
Incandescent lamp
Machine Ware
Pa.
Ohio
Mich
Mich
Location
- Ohio
•
.- Ohio
East North Central
Mid-Atlantic
Ind.
Ohio
Ohio
- Pa.- NY
- Pa.
- Pa.
Age
(yrs)
10 -
30 - 35
25
30
15 - 20
30
10
25
35
Capacity
400,000 tpy
165,000 tpy
18.0 x 106ft2/yr
37.5 x 106ft2/yr
75,000 tpy
30,000 tpy
85,000 tpy
65,000 tpy
55,000 tpy
Glass
Soda-lime
Soda-lime
Soda-lime
Soda-lime
Soda-lime
Borosilicate
Soda-lime
Soda-lime
Borosilicate
Lead
Sales Revenue
($io6)
72.
29.
26.
18.7
14.
12.
35.
30.
Fiber Glass
Textile
Wool
S.C. - N.C. - Tenn. 15
Ohio - Kan.- N.J. 20
45 x 10 Ib/yr
50 x 10 Ib/yr
Low alkali
Borosilicate
Borosilicate
15.
15.
Source: Arthur D. Little, Inc., estimates.
-------
glass production physically and often are carried out by companies not produc-
ing the raw glass. We are not aware of any plate glass production still oper-
ating in the United States. The float process glass has replaced plate glass
in the market and with the substantial capacity of greater than 1700 x 106 sq
ft/yr there is now replacement of the double strength sheet glass with float.
In the container industry there are some 130 plants (Arthur D. Little,
Inc., 1975) operated by approximately 30 companies. There is a tremendous
range of plant capacities and with the advent of triple gobs and greater
forming sections, present plants tend towards the large sizes.
Glass fiber plants, of which there are 19 in the United States, vary from
440 x 106 Ib/yr down to 20 x 106 Ib/yr (Arthur D. Little, Inc., 1972). The
four large plants with capacities greater than 100 x 10^ Ib/yr account for
70% of the total production. Of the 19 plants, 10 use rotary spinners for
fiber forming and account for 80% of the production. The remainder of the
plants use flame-attenuation.
There are four large textile fiber plants of more than 100 x 10 Ib/yr '
capacity. However, most plants are of medium capacity, i.e., 40-50 x
Ib/yr. Both direct melt and marble techniques are used to feed the platinum-
rhodium bushings for drawing fiber. Most newer operations use the direct
melt approach. By and large, textile fiber plants are multi-product plants
producing several types of fiber for different end uses and some semifinished
products (see Table A-5) .
Soda-lime-silica glasses probably account for 90% of the glass melted
in the United States (Arthur D. Little, Inc., 1975). All flat glass, con-
tainer glass, incandescent lamps and fluorescent lamp envelopes and tubing,
and a large fraction of the machine-pressed and blown ware are basically
soda-lime glasses with small difference in composition among the different
product areas (Table A- 6) .
Borosilicate glass makes up approximately 2-3% of the glass melted
and is used principally in heat-resistant laboratory ware and consumer
ovenware. A low-alkali borosilicate is used for producing most textile-
grade fiber and glass wool.
Other glass compositions melted are lead glass for electrical appli-
cations, optical glasses, and hand- formed artware. It was recently esti-
mated that lead glass represented 0.5% of total glass production. An
additional 1% of the glass melted is opal glass, a modified soda-lime-silica.
79
-------
TABLE A-5
FIBER GLASS PLANTS BY COMPANY AND LOCATION
Company
Owens-Corning
Fiberglas, Inc.
Johns-Manville
PPG Industries
Certain-Teed
Ferro Corp.
(Modiglass Fibers)
Reichhold Chem.
Fiberglass Industries
United Merchants
Oliver Glass Fiber
Textile Fiber Plants
Aiken, S.C.
Anderson, S.C.
Ashton, R.I.
Huntington, Pa.
Jackson, Tenn
Waterville, Ohio
Lexington, N.C.
Shelby, N.C.
Nashville, Tenn
Irwindale, Cal
Bremer, Ohio
Amsterdam, N.Y.
Statesville, N.C.
Farmingdale, N.Y.
Wool Fiber Plants
Barrington, N.J.
Fairburn, Ga
Kansas City, Kan
Newark, Ohio
Santa Clara, Cal
Waxahachie, Tex
Cleburne, Tex
Corona, Cal
Defiance, Ohio (3)
Parkersburg, W. Va.
Penbyrn, N.J.
Richmond, Ind
Wender, Ga.
Shelbyville, Ind.
Berlin, N.J.
Kansas City, Kan
Mountaintop, Pa.
80
-------
oo
M
TABLE A-6
COMPOSITION OF COMMERCIAL GLASSES BY WEIGHT PERCENT
Component
Si02
A12°3
B2°3
Na2°
K20
CaO
MgO
BaO
PbO
Containers
70-74
1.5-2.5
0
H
J10-14
0
0
Soda-Lime Glass
Plate and
Window Glass
71-74-
1-2
0
J12-15
J8-12
0
0
Tableware
71-74
0.5-2
0
U3-15
5.5-7.5
4.0-6.5
0
0
Borosilicate
Glass
Specialty
Glassware
70-82
2-7.5
9-14
J3-S
JO. 1-1. 2
0-2.5
0
Lead
Glass
Specialty
Glassware
35-70
0.5-2.0
0
4-8
5-10
0
0
12-60
Source: Source Assessment Document No. 3, Glass Manufacturing Plants, Monsanto Research Corporation, for EPA,
Contract No. 68-02-1320, November 1974.
-------
3. GLASS MANUFACTURING PROCESS
Although the glass industry produces a large number of different pro-
ducts and serves quite different end-use markets, there are common features
in the production process (Figure A-l). The major steps in the process are
generally as follows:
• Raw materials batching and handling
• Melting
• Fining
• Forming
• Finishing
Throughout the glass industry, the first three process steps of batch
preparation, melting, and refining are quite similar, although refining may
differ in degree for different products, such as flat glass, where optical
homogeneity is extremely important, and fiber glass, where optical proper-
ties are not critical. Batch preparation is not a significant energy-
consuming step of the process. However, melting of the raw materials to
form a viscous glass melt consumes approximately 70-75% of the total energy
used in glass production. The refining step, which homogenizes the melt,
accounts for about 5-10%, and forming and finishing, principally annealing,
15%. The remaining energy is consumed in ancillary equipment. Melting and
refining are carried out in the large continuous furnace and will obviously
receive the greatest attention in attempts to conserve energy through pro-
cess change.
4. ECONOMIC OUTLOOK
The total value of the production from this industry is about $4 bil-
lion. Over" the last 5 years, the growth has been at a rate of approximately
3.5% per year, a little less than the Gross National Product. The.major
factor that dominates the industry's growth is the growth and economics of
the principal markets: construction, automotive, packaging, and consumer
products. In the last decade, the container glass industry grew signifi-
cantly as a result of the use of nonreturnable glass beverage bottles.
This segment represents about 40-45% of the total output of the industry.
Flat glass accounts for about 15% of the industry and fiber glass and
pressed and blown glass each represent about 20% of the total output. The
total number of plants of any significant size in the industry is approxi-
mately 400.
a. Flat Glass*
While sheet glass represents about half the total shipments of flat
glass on a surface area basis during the 1968-1972 period, it represents
only 32% of total tonnage and 28% of value of shipments (Table A-7). The
*Arthur D. Little, Inc., 1973.
B2
-------
Feldspar
R2OAI202 6Si02
to yield
j Si02
Na2OandK20
Pulverized or
Granular
Other Additions
for K20, MgO,
ZnO, BaO, PbO,
eta and those for
Lining, Oxidizing,
Coloring, and
Decolorizing
Raw Material
Batching and
Handling
Side-port
Continuous Tank
Looking Down
Through Top
Submerged
Throat In
Bridgewall
Melting
and
Fining
Distributing
Temperature = 1500-2000° F_
Depending On Article
And Process
Forming Hot, Viscous Glass
Shaped by Pressing,
Blowing, Drawing, or Rolling
Finishing
Annealing
60-90 Minutes In
Continuous Belt Tunnel
Lehr; Hot Zone 900°F
~j Finishing |
Inspection and
Product Testing
Forming
Finishing
Packing, Warehousing,
and Shipping
Figure A-l. Glass Manufacture
83
-------
TABLE A-7
SHIPMENTS OF FIAT GLASS, 1968 - 1972
Sheet Glass, Including Plate, Float, and Rolled
Colored, Total and Wire Glass
OOP ft2 $000 OOP ft2 $000
1968 1,095,800 139,391 656,004 248,078
1969 1,160,950 150,123 705,244 266,747
1970 1,069,700 131,551 698,394 253,239
1971 1,188,750 150,344 943,064 314,330
1972 1,196,700 157,222 1,191,830 393,263
Source: U.S. Department of Commerce/Bureau of the Census, Current Industrial
Reports (MQ-32A) and Arthur D. Little, Inc., estimates.
level of shipments of sheet glass moved with the level of residential con-
struction and by 1972 had reached 1.2 x 109 sq ft. Window glass in single
and double strength totals 84% of sheet glass shipments. Thicker glass,
represented by plate and float increased from 656 x 10^ sq ft in 1962 to
1192 x 100 sq ft in 1972. Now, all of this market is also"serviced by float
glass.
Future growth in demand for flat glass in the United States is expected
to be at the rate of 4% for building and construction, slightly below the
anticipated GNP and at about 3% for automotive applications. About 70% of
the sheet glass consumption is for windows and other building-related appli-
cations, and 30% for miscellaneous uses, including laminated and tempered
glass for the automotive application. Of the float glass consumption, 65%
is in the automotive industry and the remaining 35% in building construction.
The projected demand over the next five years will probably average 3.8%
annually for sheet glass and 3.3% for flat. As float glass becomes tech-
nologically capable of replacing sheet in window applications, its growth
rate may be faster, at the expense of sheet.
84
-------
b. Fiber Glass*
Wool glass fiber (Table A-8) Is used primarily for building insulation
and acoustical ceiling tile, heating and cooling pipe and duct insulation,
and process equipment and appliances. Over the 1964-1971 period that market
for glass wool increased at an annual rate of about 7% to 1518 million
pounds in 1971. In the same period, sales increased from $227 million
to $427 million. In the near term, glass wool fiber growth is expected to
average at least 8% annually. This is a higher rate of growth than projected
for the U.S. construction industry, primarily because of increased demand
for insulation to conserve energy and changing insulation requirements.
The markets for textile fiber glass (Table A-9) are home furnishings,
industrial applications, and reinforced plastic. The latter, with 66% of the
total consumption, is by far the largest. Home furnishings represent 11% and
the industrial applications 20% of this market segment. The use of glass
fiber in household furnishings, principally draperies, has reached a high
market penetration and further growth will be slow. However the fire-
retardant characteristics of glass fiber- are responsible for some recent
acceleration in the market. In the near term, the home furnishing market
should grow at about 5% per year. A major uncertainty in the market is the
future of the textile glass fiber business in the vagaries of the automotive
tire market. The recent switch to steel radial tires in a large portion of
the U.S. auto market indicates that glass belts for belted-bias tires may
continue to decrease.
The applications for glass fibers in reinforced plastics are extremely
diverse, with the largest end-use markets being marine structures, transpor-
tation, principally passenger cars, corrosion-resistant material, and con-
struction. The use of glass fiber in reinforced plastics is expected to be
the fastest growing segment of the market with a rate of about 15%; the
industrial application market will grow at a lower rate, perhaps 11% per
year. Therefore, over the next five years, the total glass fiber market may
grow at a rate of 13%.
Historically, the textile fiber glass business has not been a highly
profitable one and, considering the rather substantial investment in plant
and the high technology required to participate, it is doubtful that sub-
stantial expansion will take place. Certainly history has shown that it is
difficult for new entries to get into this segment of the industry.
c. Pressed and Blown Glass**
Compared to other segments of the glass industry the pressed and blown
segment, has had a somewhat better historical growth pattern, particularly
the part related to electronics and lighting, which has been growing rapidly
over the past decade.
*Arthur D. Little, Inc., 1972.
**Arthur D. Little, Inc., 1975.
85
-------
00
TABLE A-8
U.S. SHIPMENTS AND VALUE OF WOOL GLASS FIBER, 1964-1971
Insulation Use
Structural Building
Industrial, Pipe &
Equipment
Total
Average
Insulation Use
Structural Building
'Industrial, Pipe &
Equipment
Total
Average
1964
1965
1966
1967
10 ID
368
570
938
f
10°lb
557
567
1124
$10"
76
151
227
1968
f
$10°
133
179
312
C/lb 10"lb $10" c/lb
20.7 438
26.5 608
1046
24.2
f
C/lb 10 Ib
23.9 627
31.6 675
1302
93 21.1
158 26.0
251
24.0
1969
f.
$10° C/lb
158 25.2
198 29.3
356
10 Ib
484
608
1072
106lb
644.8
541.5
1186.3
$10
105
173-
278
1970
f.
$ioc
165.6
190.6
355.8
C/lb 10 Ib $10 c/lb
22.6 484 109 22.5
28.5 554 170 30.7
1038 279
25.9 26.9
1971
C/lb 10£lb $106 C/lb
25.7
35.2
1518.7 426.9
27.8 27.3 30.0 28.2
Note: Values are average manufacturers' net selling prices, f .o.b. plant, after discounts and allowances, and
excluding freight and excise taxes.
Source: Department of Commerce "Current Industrial Reports".
-------
oo
TABLE A-:9
U.S. SHIPMENTS AND VALUE OF TEXTILE GLASS FIBER, 1964-1971
1964 1965 1966 1967
10 Ib $10 c/lb 10"lb$10^c/lb IC^lb $10c/lb l(r$l(rc/lb
Yarn, Strand, Mat 156.0 83.7 53.7 191.0 101.3 53.0 211.5 116.5 55.1 189.8 100.0 52.7
Roving, Chopped Strand
Milled Fiber 73.9 23.8 32.2 95.6 26.7 27.9 116.1 35.2 30.3 118.8 37.5 31.6
Total 229.9 107.5 286.7 128.0 327.6 151.6 308.6 137.5
Average 46.8 44.6 46.3 44.6
1968 1969 1970 1971
10 Ib $10c7lb 10°lb $10° c/lb 10°lb $10 C/lb 10 $10 C/lb
Yarn, Strand, Mat 234.4 121.2 51.7 n.a. n.a. n.a.
Roving, Chopped Strand,
Milled Fiber 160.1 51.3 32.4 n.a. n.a. n.a.
Total 394.5 173.0 477.4 227.4 432.8 192.9 477.6 214.6
Average 43.9 43.6 44.5 44.5
Note: Values are average manufacturers' net selling prices, f.o.b. plant, discounts and allowances, and
excluding freight and excise taxes.
Source: Department of Commerce "Current Industrial Reports".
-------
The machine-made consumer glassware (Table A-10) Is the largest single
part of this industry segment, accounting .for 35% of the total payment and
balance value of shipments in 1972. The products are tumblers, stemware,
tableware, cookware, ovenware, kitchenware, and ornamental, decorative, and
novelty glassware. Tableware and kitchenware make up 46% of the product
value. During the 1967-1972 period this, business grew significantly,
about 65%, equivalent to an annual growth of 10.3%. In that time period,
the value of shipments increased considerably faster than the quantity as
unit prices increased 30-40%. The outlook is for continued growth in ship-
ments at about the rate of GNP growth. A more rapid increase in value is
anticipated as selling prices are increased to reflect increased cost of
energy and labor.
Total shipments of glass tubing in 1972 were $55 million, with $40 mil-
lion, or 73%, accounted for by tubing for fluorescent and neon lighting and
the remaining from nonelectrical glass tubing (Table A-ll). The growth in
dollar value of the industry shipments has been somewhat erratic. Current
dollar shipments' of tubing for fluorescent and neon tubing have grown at an
average annual rate of about 4.5%, while shipments of nonelectrical tubing
have grown only 1.8%. The industry's growth is expected to continue to be
cyclic because of its close relationship to the construction industry. It
appears "that there is really no material competition with glass in the major
lighting applications; therefore, no major changes are expected in this
business.
Light bulb blanks (or envelopes) for incandescent lighting, a portion
of the lighting and electronic glassware industry, are specifically covered
by SIC Code'3229225. U.S. Department of Commerce Reports lump shipment and
value statistics for this industry together with industry 3229235, television
tube blanks and parts, and tubing, cane and other glass parts for electronic
tubes and devices. In 1972, the total value of shipments for these combined
industries was $253 million, of which television tube envelopes and parts
accounted for about two-thirds, electronic tube parts about one percent, and
electric lamp envelopes the remainder, or about 33%. According to this break-
down, the 1972 value of shipments for electric light bulb blanks was about
$84 million. Television tube face plates and funnels were valued at
$166 million.
d. Glass Containers*
In terms of unit shipments (which closely approximate industry pro-
duction) , in the past several years the glass container industry has exhibited
modest growth, increasing from 253,198,.QOO gross in 1969 to 266,000 gross in
1972, for an average annual growth rate of 1.8% (Table A-12). The dollar
volume, however, has increased considerably more rapidly, as the value per
gross increased from $6.08 in 1969 to $7.71 in 1972. Total dollar value of
shipments increased by 33.3%, or 10% per year during this period. A trend
toward larger containers helps explain this change. The glass container
*Arthur D. Little, Inc., 1975.
38
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TABLE A-10
SHIPMENTS, EXPORTS, IMPORTS, APPARENT CONSUMPTION: MACHINE ^lADE
CONSUMER GLASSWARES, 1969-1972
($000)
Year
1969
1970
1971 y
1972
% Change
From 1969 to
1972 Annual
Growth Rate (%)
Total
Shipments
274,661
268,749
326,291
380,794
+ 38.6
A
Exports Imports
20,663
21,608
24,776
A*
29,512
+ 42.5
2,319
2,576
2,625
4,148
+ 78.9
Apparent
Consumption
256,317
249,717
304,140
355,430
+ 38.7
Imports (% of
Consumption)
0.9
1.0
0.9
1.2
+ 11.5 + 12.4 + 21.0
+ 11.5
**
Includes value of product at port of shipment, plus calculated import
duty into U.S.A. Imports of machine-made product are assumed to be 5%
of total consumer glassware as per U.S. Tariff Commission Report, TC
Publication 257, 1968.
Estimate.
Source: U.S. Department of Commerce Bureau of Census, U.S. Census of
Manufactures, 1972.
89
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TABLE A-ll
SHIPMENTS OF GLASS TUBING, 1964-1974
VO
o
Tubing for Fluorescent
and Neon Lighting-
All Tubing Except
Electrical and Electronic
Total
Year
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
$000
28,207
31,083
36,397
33,384
34,230
35,963
37,744
38,481
40,151
45,386
42,958
% Change
—
10
17
-8
3
5
5
2
4
13
-5
$000
13,100
13,219
17,297
19,123
19,054
22,743
21,667
15,859
15,079
(D)
(D)
% Change
—
1
31
11
0
19
-5
-27
-5
—
—
$000
41,307
44,302
53,694
52,507
53,284
58,706
59,411
54,340
55,230
—
—
% Change
—
7
21
-2
1
10
1
-9
2
—
—
Annual Compound
Growth Rate
1964-1972 (%)
4.5
1.8
3.9
(D) Withheld to avoid disclosing figures of individual companies.
Source: U.S. Department of Commerce, Current Industrial Reports: Consumer, Scientific, Technical, and Industrial
Glassware Series MA-32E.
-------
TABLE A-12
SHIPMENTS, IMPORTS, EXPORTS AND APPARENT CONSUMPTION:
GLASS CONTAINERS, 1969-1972
Year
Total
Shipments
($000)
Exports
Imports
Apparent
Consumption
Imports (% of
Consumption)
1969
1970
1971
1972
1,636,685
1,830,213
1,922,723
2,055,686
16,292
15,079
15,173
14,982
5,853
5,631
6,700
9,274
1,626,246
1,820,765
1,914,250
2,049,960
0.4
0.3
0.4
0.4
% Change from
1969 to 1972
+25.6
-7.9
+58.5 '
+26.1
Average Annual
Growth Rate (%)
+7.9
-3.0
+16.6
8.0
Source: United States Department of Commerce, Bureau of Census, Census of
Manufactures, 1972.
industry produces a wide variety of products, ranging from perfume bottles
to five-gallon water bottles and large carboys. Three types of glass con-
tainers, however, account for the bulk: nonreturnable soft drink bottles,
nonreturnable beer bottles, food bottles and jars (Table A-13). Combined,
these represented almost 75% of all glass containers shipped in 1972.
For the past several years, nonreturnable soft drink bottles have con-
stituted the fastest growing segment of the glass container industry, growing
at an average annual rate of nearly 30% in the last half of the 1960's
(Table A-14). This type of container grew from 4% of the total glass con-
tainer shipments in 1954 (on a unit basis) to 23% in 1972. The rapid growth
of this product, however, appears to be receding as the nonreturnable bottle
has reached a mature stage in its life cycle. Returnable beverage bottles,
the main product displaced by the nonreturnables, seem to have reached a
point where further declines will be slow. Metal cans, the other major
packaging used for soft drinks, will probably show small increases in market
share. Currently, nonreturnable glass beverage containers have about 28%
of the market; cans have about 35%; and returnable bottles about 37%.
91
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TABLE A-13
DOMESTIC SHIPMENTS OF GLASS CONTAINERS, 1972
Type
Food
Beverage, nonreturnable
Beer, nonreturnable
Medicinal and Health
Liquor
Beverage, returnable
Toiletries and Cosmetics
Wine
Household and Industrial
Beer, returnable
r
Dairy Products
(000 gross)
82,574
60,954
52,705
20,620
13,873
10,099
9,272
8,552
4,282
1,699
238
Percent of
Total Units
(M)
31.2
23.0
20.0
7.8
5.2
3.8
3.5
3.2
1.6
0.6
0.1
Value
(000$)
291,336
461,770
265,525
112,473
161,394
135,922
68,815
120,619
35,073
11,825
4,744
Percent of
Value
17.5
27.7
15.9
6.7
9.7
8.1
4.1
7.2
2.1
0.7
0.3
264,869
100.0
1,669,496
100.0
Source: U.S. Dept. of Commerce M32 G, (72)-13
92
-------
TABLE A-14
GLASS CONTAINER SHIPMENTS BY TYPE, 1967-1972
(000 gross)
Food
Medicinal and Health
Household and Industrial
Toiletries and Cosmetics
Beverages, returnable
Beverages, nonreturnable
Beer, returnable
Beer, nonreturnable
Liquor
Wine
Dairy Products
1972
82,574
20,620
4,283
9,272
10,099
60,954
1,699
52,705
13,873
8,552
238
1967
81.483
.22,603
5,664
15,913
13,282
24,899
4,332
40,169
13,752
5,707
958
Percent
Change
+ 1.3
- 8.8
- 24.4
- 41.7
- 24.0
+ 144.8
- 60.8
+ 31.2
+ 0.1
+ 49.9
- 75.2
TOTAL
269,869
228,766
+ 15.8
Source: U.S. Dept. of Commerce, Bureau of Census, Census of Manufactures, 1972.
93
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In beer packaging, metal cans have been growing rapidly at the expense
of glass. From a market share of 58% (including both returnable and non-
returnable) in 1965, glass usage has dropped to about 40% of total beer
packaging requirements, and a further erosion is anticipated because of
consumer preference for the nonbreakable cans and the industry's desire to
take advantage of the ability of cans to be filled more rapidly than bottles.
Glass food containers are the single largest category of glass con-
tainers, and are expected to remain so in the foreseeable future. The steady
rise in food production, especially in prepared food products, will more than
offset anticipated inroads of plastic containers in the food industry.
Glass container use for medicinal and health products, household and
industrial items, toiletries and cosmetics, liquor, and dairy products has
been either stable or declining in recent years, as plastic containers,
aerosols and paper have taken all the growth in these markets. Therefore,
we predict that total usage will remain stable.
The glass container industry, aware of its competition from other
packaging materials, has been highly concerned with product developments
involving product cost, utility, and safety. Significant recent develop-
ments have been the resealable twist-off cap for nonreturnable bottles,
composite plastic-glass bottles, and the chemical tempering of glass con-
tainer surfaces for added strength. The resealable bottle cap has prompted
a significant shift to larger bottles in the soft drink market.
The glass container business is an extremely competitive, mature
industry. Growth in both volume and dollar value of shipments is expected
to be at rates significantly lower than GNP growth. From 1973 through 1980,
glass container shipments of all types are expected to grow at rates of
about 1% per year. Because of shifts in product mix and to higher prices,
dollar values will grow by about 4% per year.
'94
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REFERENCES
Arthur D. Little, Inc., Economic Analysis of Effluent Guidelines - The
Pressed and Blown Glass Industry, for EPA, Contract No. 68-01-1541,
January 1975.
Arthur D. Little, Inc., Economic Analysis of Proposed Effluent Guidelines -
Flat Glass Industry, for EPA, Report No. EPA-230/1-73-013, August 1973.
Arthur D. Little, Inc., Initial Economic Impact Analysis of Water Pollution
Control Costs upon the Fiber Glass Industry, for EPA, Contract No. 68-01-
0767, December 1972.
95
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APPENDIX B
ENERGY USE: BASE LINE PROFILE*
1. ENERGY USE BY PROCESS STEP
For purposes of identifying the energy use and intensity by process
steps, we added two additional categories - i.e., product handling and space
conditioning - to the principal process steps in glass manufacturing (defined
in Appendix A). Although the process technology varies considerably
depending on the product being produced, these two categories are considered
to be similar in all glass manufacturing processes, as are batch handling
and melting. Because of special situations, the process difference can
influence the distribution of energy in a specific plant. For instance,
although the melting function normally consumes 60-80% of the total energy,
a fiber glass operation requires large quantities of high-temperature gas to
carry out the forming operation. Thus the forming step is more energy inten-
sive than in other glass processing.
The energy consumption by major process step (Table B-l) can vary con-
siderably from plant to plant making identical products. But obviously, the
melting of glass is the single greatest consumer of energy in the process.
Therefore, it is certainly in this process step that significant changes in
energy consumption patterns might be made. We do not suggest that energy
savings cannot be made in other process functions: manufacturers are
carrying out many modifications and housekeeping improvements to alter energy
use. But by virtue of the vast amount of energy consumed in melting glass,
this function has become the focus of energy-related process modifications.
Many factors specifically affect the energy use in melting glass: i^e.,
type of glass, type and size of furnace, method of operation, type of fuel,
pull rate, furnace age, and specific construction. Furnaces are designed and
constructed on the basis of a single fuel - usually natural gas - and the use
of an alternative fuel usually results in a loss in efficiency.
Although batch handling and product handling appear to consume rather
consistent portions of total energy regardless of .the specific process, space
conditioning can vary significantly. Some of these increases in consumption
in space heating and cooling are due to such factors as the controlled
humidity required in rooms where textile fibers are formed.
*Battelle Columbus Laboratories, Final Report on Industrial Energy Study
for the Glass Industry, for FEA, Contract No. 14-01-0001-1667, December
1974.
96
-------
TABLE B-l
PERCENT OF TOTAL PLANT ENERGY CONSUMPTION BY INDUSTRY SEGMENT AND PROCESS STEP
Segment
Batch Melting & Post Product Space
Handling Fining Forming Forming Handling Conditioning
Flat Glass
Sheet
Float
Glass Containers
Pressed and Blown
Machine Ware
Lamp Envel., T.V. &
Tubing
Glass Fibers
Textile
Wool
1.2
1.2
2.0
2.0
1.0
2.0
2.0
75
76
70.0
55.0
65.0
45.0
40.0
2.0
5.0
1.5
15.5
14.0
28.0
38.0
2.0
7.0
9.5
20
15
10.0
12.0
1.3
1.3
2.5
-
7.0
2.0
3.0
2.0
18.5
9.5
4.5
6.0
3.0
12.0
6.0
-------
2. FORM OF ENERGY USED
The six forms of energy used by the glass manufacturing industry are
natural gas, electricity, distillate fuel oil, residual fuel oil, propane,
and coal (Table B-2). Overall the industry average use is as follows:
Percent of Total
Natural gas 70.2
Electricity 20.6
Distillate fuel oil 4.6
Residual fuel oil 3.9
Propane 0.3
Coal 0.4
Over recent years, there have been some small shifts in the patterns
of use of the above forms of energy. The relative fuel oil consumption has
increased and the percent of natural gas has declined, reflecting the supply
problem facing the industry. The relative amount of coal used has declined,
presumably due to environmental constraints on the use of coal for firing
boilers.
Within the various segments, the distribution of energy source use on
a percentage basis is not large; however, the largest use of propane and
distillate fuel is in the glass container segment. On the other hand, the
flat glass segment has increased its use of residual fuel oil. The distri-
bution of natural gas and.electricity has remained nearly evenly distributed
across the major segments.
Oil and propane are the usual standby, or substitute, fuels for the
melting processes. Fuel oil has also been substituted for coal in boilers
to make process steam and for space conditioning.
In the United States, natural gas has been used as the primary source
of energy for many years: it was a low cost, available, clean, easy to
handle fuel. In 1973, it accounted for about 70% of the total energy used
in a glass plant. The principal use of natural gas in the integrated
glass plant is in the melting function, which consumes 60-80% of the total
energy used in a typical glass plant. The specific requirement depends on
the product and type of glass. In addition, annealing is carried out as a
post-forming operation, and natural gas for this operation constitutes up to
10% of the total plant energy consumption. Natural gas is used for space
conditioning, and that non-process function may be as high as 45% of the
total, such as in some textile marble melt operations.
98
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TABLE B-2
RELATIVE USE OF DIFFERENT ENERGY FORMS, 1973
Segment
Energy Used
%(109 Btu) Type of Fuel
10 Btu/$
Shipment
10 Btu/ton
Flat Glass
Sheet
Float
20 (65,660)
79. Gas
14.9 Electric
1.1 Coal
6.4 Fuel Oil
63
17.2
Glass Container
48 (155,230) 70. Gas
17. Electric
4. Fuel Oil
-7.8 Mid. Dist.
74
13.7
Pressed and Blown 26 (79,920)
69. Gas
25. Electric
3. Fuel Oil
2.6 Mid. Dist.
64.7
43.8
Industry
100
70. Gas
20.6 Electric
3.9 Fuel Oil
4.6 Mid. Dist.
0.3 Propane
0.4 Coal
56,200
Source: Final Report on Industrial Energy Study of the glass industry,
Battelle Columbus Laboratories for FEA, Contract No. 14-01-0001-1667,
December 1974.
99
-------
Fuel oil, either distillate or residual, is a viable alternative fuel
to natural gas for melting. But as a replacement, it has limitations: it
cannot be used in annealing lehrs or in forehearths. The recent increased
use of fuel oil is a direct result of the shortages of natural gas. His-
torically, the glass industry does not have a strong position if oil allot-
ments are based on past usage.
Electrical energy is used throughout the entire glass plant, primarily
for motors for plant heating and cooling and in forming and finishing oper-
ations. Of importance is the increased use of electrical energy for melting
when, with certain constraints, it is a viable alternative.
Propane is primarily a standby fuel for melting and post-melting oper-
ations. Its cost and availability limit broad application except in drastic
shortage situations.
100
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APPENDIX C
PROCESSES CONSIDERED
In the analysis of likely process changes in glass manufacturing because
of energy cost or shortages, the focus in this study is entirely upon the
melting operation. This operation accounts for 60-80% of the energy con-
sumption in a glass plant and, therefore, is the one unit process which offers
the industry an opportunity to make any significant change in the energy con-
sumption patterns. In the United States, 85-90% of glass melting is carried
out with natural gas. The energy consumption varies significantly from plant
to plant because of product differences and furnace type, size and operation.
In the short term^ oil will no doubt continue to replace natural gas.
Heavy fuel oil is quite acceptable as an alternative to natural gas for
melting glass, but special problems require that the sulfur content be no
more than 2% and the vanadium (as V205) content be no greater than 200-
400 ppm. The use of oil considerably increases refractory wear, especially
with high-sulfur oil. Furthermore, oil flame temperatures and velocities
are greater than those of natural gas, resulting in increased NOX, 802/803
and particulate emissions and higher volatization from the glass melt. On
the other hand, with oil-firing waste gas heat losses are reported to be
lower than with natural gas and oil flame emissivities greater, giving
improved melting rates. Some areas of Western Europe have had extensive
experience with oil-fired glass melting furnaces and this experience could be
a useful source for comparison. This approach is considered fuel switching
and not pursued.
Another short-term alternative is the use of electric boosting of
fossil-fuel-fired glass melting furnaces. This technique has been useful to
increase capacity in existing furnaces without extensive capital expenditures.
In gas or oil firing, the heat is transferred from the flame over the glass
melt by radiation from the flame and the heated superstructure. Convection
currents in the glass melt distribute this absorbed heat throughout the melt
depth. In electric melting, the glass melt is heated directly by passing a
high current through the conductive glass melt via electrodes inserted in
the wall or bottom of the furnace.
The energy introduced by electric boosting is small relative to the
total energy input; however, it is utilized at something approaching 100%
efficiency. Experience varies with specific installations, but 350-400 kWh
of electricity per ton of glass produced has been reported. In a typical
operation, electric boosting may increase the furnace output by up to 25%.
Increased use of electric boosting would shift the energy consumption to
perhaps less critical types of fuel.
101
-------
Complete electric melting has been used with success in the United
States. But, because of the high cost of electrical energy and the present
limitation on the size of all electric furnaces, there are relatively few
installations. All electric furnaces involve complete new furnace con-
struction and not simply retrofitting, as is the case with electric boosters.
The efficiency is claimed to be as high as 80% (-800 kWh per ton) (McGovern,
1972). The surface melt temperatures are low and the volume of waste gases
is small; therefore, the air pollution problems are considerably reduced.
This is of particular advantage in melting glass containing lead or fluorine.
It is not clear if there are technical limitations on furnace size since
the much higher tonnage output of these furnaces has not required that
furnaces as large as gas-fired ones be built.
Oxygen enrichment has been used by several glass manufacturers (Allen,
1970; Leone, 1973; Leone, 1974) as a means of increasing the pull rate of a
glass furnace. The effect of oxygen enrichment is to increase the flame
temperature so that a higher melting rate is achieved, hence, more-tons per
day of glass are pulled from a given furnace. It has been reported that by
increasing the oxygen content of the combustion air from 21% to 23% an
increase in glass pull rate of about 11% can be achieved, assuming that the
number of rejects in the finished product does not change. The purpose in
shifting to oxygen enrichment is to increase capacity for short periods of
time in order to meet demand with essentially the same equipment and manpower.
However, the high flame temperature imposes severe operating conditions upon
the refractories, especially the silica crown roof.
The increase in pull rate obtained by oxygen enrichment can also be
viewed as a corresponding savings in fuel consumption per ton of glass. This
fuel savings is a real energy savings because it takes less energy to pro-
duce the required amount of oxygen to raise the oxygen content of the air
stream from 21% to 23%.
Assuming that this technology were to be added to current practice,
the effect on air pollution control costs would be reflected as an increase
in baghouse costs. On a per-ton-of-glass-pulled basis, sulfur emissions
will not be altered; NOX would increase because of the increased flame tem-
perature; and, as indicated above, particulate emissions would be increased.
However, there'would be no new species of emission that would require changes
in the pollution control equipment. Oxygen enrichment would increase bag-
house costs by 10-15%.
102
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The principal deterrents to the increased use of oxygen enrichment of
fossil fuel firing of glass melting furnaces are the cost of oxygen and the
possible effect of the higher flame temperatures on the furnace life. The
use of oxygen would appear to be more of an interim solution, and as experi-
ence in controlling furnace operating conditions is gained, could be a
viable technique to reduce natural gas consumption per ton of glass. Essen-
tially, except for an increase in the cost of pollution control, no additional
capital costs are expected for this alternative.
Waste heat from the melting furnace and possibly from other parts of
the process could be utilized to preheat the incoming load (glass batch) to
the furnace. Depending upon the specific operating conditions, from one-
quarter to one-half of the energy to melt glass could be obtained from waste
heat. By heating the glass batch outside the furnace, better utilization
can be made of the energy. Such a preheat operation is difficult to accom-
plish without modification of the batch handling methods. Heat transfer to
the conventional loose batch is low when the direct exhaust gases simply flow
through. Additional problems include the entrainment of some of the small
batch particles by the exhaust stream, thereby increasing air pollution
problems. Water vapor in the exhaust gases could also condense on the batch
and complicate batch handling. Also, the additional length and movement of
the batch in such a preheating process would increase the segregation, or
demixing, of the batch mix, i.e., separation of the light and heavy particles
of the mix.
These complications plus the additional capital investment and space
requirements (frequently nonexistent) have precluded the use of batch pre-
heating (Schorr, Battelle) to date. One proposed solution to batch preheat-
ing is to convert the glass batch into an agglomerate such as a pellet or
a briquette. Once agglomerated, the glass batch can be preheated without
the aforementioned problems. While there are a number of technical problems
to be solved, in at least one instance a container glass batch was contin-
uously pelletized, dried and preheated to temperatures as high as 1500°F.
Recent work in Japan on agglomerated batch indicated that outputs were
increased by as much as 50%. This approach is considered a longer-term
alternative to electric boosting, electric furnace, and oxygen enrichment.
Within one segment of the glass industry, flat glass (Arthur D. Little
Inc., 1973), the development of the float glass process in the 1950's has
resulted in major process changes. Since the introduction of the float glass
process, float glass has rapidly replaced plate glass. At first the bulk of
float glass had been sold to markets formerly served by plate glass. As the
103
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technology developed to the point where glass thinner than 1/4" could be
produced by float, not only construction markets but the important automotive
jjlass markets switched to float glass. As of now, the replacement of plate
by float glass is essentially complete. The driving force has been the sub-
stantially improved economics of the float process in terms of yield, produc-
tion rate, and lower energy and labor cost.
The tremendously rapid increase in float capacity in the recent past
and the planning of new facilities has raised a question concerning the
supply/demand of float glass. With the replacement of plate glass by float
complete, it is expected that float glass will penetrate the sheet glass
market as well. At least one firm has already announced its intention to
use an intermediate-quality float glass in its double-strength window glass
market now served by sheet glass. The investment in float glass facilities
by the major producers - 10 times more than in sheet and plate facilities
combined - seems to substantiate the trend.
By and large, the future capacity of the plate and sheet facilities in
the United States will probably be governed by economic and marketing factors,
including the cost and availability of energy. Although specific data are
not available at this time, the phasing out of many old, inefficient sheet
glass plants would save energy.
Changes in the feedstock to the furnace could have impact on the
energy consumption of the melting process. Glass Container Corp (GCC) claims
that by using 60% cullet it can save as much as 1 million gallons of oil each
year in the manufacture of 200,000 tons of glass containers (Business Week,
March 1975). With 25-30% cullet in the furnace charge the energy savings
can amount to 15%. Most glass container manufacturers use 10-15% cullet,
and most of this cullet is "house cullet."
Increasing usage of cullet could reduce the need for pollution control
equipment. Cullet usage reduces particulate emissions, and GCC claims that
at the 60%-cullet level electrostatic precipitators would not be required.
There are, however, several constraints in recycling glass wastes as
cullet. Although the glass container manufacturers have supported recycling,
to date, post-consumer cullet (cullet obtained from the consumer), on the
average, only accounts for 2% of the furnace charge. The cullet is derived
from the separate collection of discarded container from recycling centers,
dumps, curbside pick-up, etc.
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The future availability of post-consumer cullet from mechanical resource
recovery systems remains an unknown quantity for the following reasons:
• The high costs of transportation versus the relatively low value
of cullet,
• The need for stringent cullet specifications,
• The limited market for clean mixed-color cullet,
• The absence of a commercially operating facility that produces
acceptable cullet,
• The high capital investment required to install a glass recovery
subsystem, and
• The questionable economics of a mechanical glass-recovery system.
Recycling post-consumer cullet by separate collection has continued to
increase each year. In 1974, 2-3% of the glass containers were collected and
recycled (Starrett, 1975). Nevertheless, in 1980 no more than about 4% of the
glass container production will be recycled by separate collection.
About 30-35 major resource-recovery facilities are in operation, under
construction, or in the planning stage in this country. But, many resource
recovery operations will not recover cullet because the economics are unfav-
orable, or they may recover a crude glass fraction for secondary applications,
other than glass container manufacture. By 1980, as much as 30,000 tpd of
raw refuse could be processed in resource recovery operations with glass sub-
systems. Taking into account the different efficiencies of the present cullet
recovery processes, about 525,000 tons of cullet will be recovered per year.
On this basis, cullet recovered from municipal solid waste would amount to
about 4% of the glass container shipments (by weight) in 1980.
Today, "house cullet" accounts for 10-15% of the furnace charge, and
most glass container manufacturers purchase another 5%. Therefore, if esti-
mates for post-consumer cullet are correct, it is expected that the average
glass container manufacturer might use about 20-25% cullet by 1980, instead
of 15-20%.
In summary (Table C-l), electric boosting and the substitution of oil
and/or propane for natural gas are being used when and where appropriate.
(Substitution of oil or propane is considered simple fuel switching and is
not considered here.)
105
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TABLE C-l
SUMMARY OF SEVERAL PROCESS MODIFICATIONS CONSIDERED
FOR THE MELTING PROCESS
Present or Near-Term
Energy-Related Modifications
of Melting Process
Oil
Propane
Increased use of Electric
Boosting.
Potential Melting Process
Changes for Future
Direct fire coal*
On-site coal gasification*
All electric melting*
Batch preheat*
Submerged burner**
Oxygen enrichment**
Recycle cullet**
Hot gas generator**
*High priority - detailed analysis
**Low priority - qualitative comments
The high priority process modifications are considered to be direct
fire with coal, use of coal gasification, all electric melting, and batch
or agglomeration preheat. The other possibilities, such as submerged burner,
oxygen enrichment and recycling of cullet, may present viable alternatives,
but were assigned lower priorities. During this program, another coal-related
process, coal-fired hot gas generation, was identified and appeared to have
sufficient merit to warrant its inclusion.
106
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REFERENCES
APPENDIX C
1. Allen, A.C., "Underwood Boosts Glass Melting 126%," Ceramic Industry,
pp. 28-30, March 1970.
2. Business Week, March 31, 1975 (Industrial Edition).
3. Leone, J.G., "How to Start Your Own Glass Company and Get More Glass Per
BTU," The Glass Industry, p. 8, September 1973.
4. Leone, J.G., "New Melting Process Saves Fuel," The Glass Industry,
pp. 16-17, February 1974.
5. Arthur D. Little, Inc., Economic Analysis of Proposed Effluent Guidelines
Flat Glass Industry, for EPA, Report No. EPA-230/1-73-013, August 1973.
6. McGovern, D., J. Institute of Fuel, pp. 470-475, Aug/Sept. 1972.
7. Schorr, J.R., Private Communication, Battelle Laboratories, Columbus,
Ohio.
8. Starrett, Robert, "Should Glass Bottles be Recycled?" Glass Industry,
p. 34, September 1975.
107
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APPENDIX D
BIBLIOGRAPHY
Addle, Don, "Energy Key to Glass' Future," Ceramic Industry, August 1973.
Allen, Alfred C., ed., "Underwood Boosts Glass Melting 126%," Ceramic
Industry, March 1970.
Alexander, Frank, "Why Regenerator Glass Melters," The Glass Industry, May
1974.
"American Optical Fights Pollution," The Glass Industry, December 1972.
Anders, Glenn Y., "Submerged Combustion Saves Space," Ceramic Age, March
1971.
Arrandale, R.S., "Furnaces, Furnace Design and Related Topics," Handbook of
Glass Manufacture, V.I, Fay V. Tooley (ed.), Books for Industry, New York,
1974.
Arrandale, R.S., "Fuels and Fuel Economics," Handbook of Glass Manufacture,
F.V. Tooley (ed.), Books for Industry, New York, 1974.
Battelle Laboratories, Final Report on Industrial Energy Study of the Glass
Industry, Columbus, Ohic>7 for EPA, Contract No. 14-01-0001-1667, December
1974.
"Clean Fuel from Coal," The Glass Industry, August 1973.
U.S. Dept. of Commerce, Bureau of Census, 1972 Census of Manufactures.
Dow Chemical Company, "Energy Consumption, Paper, Stone/Clay/Glass/Concrete.
and Food Industries," for USEPA, NERC-RTP, Contract Np. 68-02-1329, Apr. 1975.
"Energy Gap for Glass?" The Glass Industry, November 1971, Part 1; The Glass
Industry, December 1971, Part 2; The Glass Industry, January 1972,
Conclusion.
Engelleitner, William H., "Pellets Cut Cost Improve Quality," The Glass
Industry, March 1972.
<>
FEA Project Independence Blueprint, Final Task Force Report, Vol. 3, November
1974.
108
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Cell, P.A.M., "Electric Melting for Larger Tonnage Furnaces," The Glass
Industry, March 1973.
Hamilton, J.C., "Applied Research in Glass Melting," Industrial and Engineer-
ing Chemistry, Vol. 62, No. 2, February 1970.
Hicks, John F.G., "The Economics of Electric Melting Compared to Combustion
Melting of Container Glass," The Glass Industry, March 1966.
Hsu, James P., "Heat Balance and Calculation of Fuel Consumption in Glass-
making," The Glass Industry, January 1971.
Leone, J. G., "How to Start Your Own Glass Company and Get More Glass
Per BTU," The Glass Industry, September 1973.
Leone, J.G., "New Melting Process Saves Fuel," The Glass Industry, February
1974.
Arthur D. Little, Inc., Economic Analysis of Effluent Guidelines - The
Pressed and Blown Glass Industry, for EPA, Contract No. 68-01-1541, January
1975.
Arthur D. Little, Inc., Economic Analysis of Proposed Effluent Guidelines -
Flat Glass Industry, for EPA, Report No. EPA-230/1-73-013, August 1973.
Arthur D. Little, Inc., Initial Economic Impact Analysis of Water Pollution
Control Costs upon the Fiber Glass Industry, for EPA, Control No. 68-01-0767,
December 1972.
Loesel, Robert E., "Practical Data for Electric Melting," The Glass Industry,
February 1975.
Makhijani, A.B., and Lichtenberg, A.J., "Energy and Well-Being," Environment,
Vol. 14, No. 5, June 1972.
Marshall, R.W., and Reed, R.J., "Guard Against Fuel Failure," Ceramic Age,
December 1971.
McGovern, D., "Energy Utilization in the Glass Industry," J. Institute of
Fuel, August/September 1972.
Miller, K.A. and Fogelbery, CIV., "Pulverized Coal-Air Burners for Glass
Tanks," The Glass Industry, March 1975.
Monsanto Research Corporation, Source Assessment Document No. 3 - Glass
Manufacturing Plants, for EPA, Contract No. 68-02-1320, November 1974.
Moore, Henry, "All-Electric Melting," The Glass Industry, April 1974.
Morse, C.E., and Manring, W.H., "A Practical Solution to Minimize Carryover
Plugging of Regenerative Glass Furnaces," Ceramic Bulletin, Vol. 50, No. 5,
1971.
109
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Nelson, S., Private Communication, Applied Technology, Inc., Pittsburgh, Pa.
"New Melting Process Saves Fuel," Ceramic Industry, February 1974.
Penberthy, L., "Electric Melting of Glass," Handbook of Glass Manufacture,
Fay. V. Tooley (ed.), Books for Industry, New York, 1974.
Penberthy, L., "Recent History of Electric Melting of Glass," The Glass
Industry, March 1973.
Schorr, J.R., Private Communication, Battelle Laboratories, Columbus, Ohio.
Stockham, John D., "The Composition of Glass Furnace Emissions," J. Air Poll.
Control Assoc., Vol 20, No. 11, November 1971.
Sullivan, Michael J., "Hypothesis: Electric Melting is Cost Effective," The
Glass Industry, September 1974.
"Tank Emissions Bagged," The Glass Industry, July 1974.
Teisen, K., "New Designs in Recuperative Tanks," The Glass Industry, August
1973.
Tooley, F.V., "Raw Materials," Handbook of Glass Manufacture, Fay V. Tooley
(ed.), Books for Industry, New York, 1974.
Wormser, Alex, Private Communication, Wormser Engineering, Marblehead, Mass.
110
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-76-034k
3. RECIPIENT'S ACCESSIOP*NO.
4. TITLE AND SUBTITLE
ENVIRONMENTAL CONSIDERATIONS OF SELECTED ENERGY CON-
SERVING MANUFACTURING PROCESS OPTIONS. Vol. XI.
Glass Industry Report
5. REPORT DATE
December 1976 issuing date
6. PERFORMING ORGANIZATION CODE
7, AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Arthur. D. Little, Inc.
Acorn Park
Cambridge, Massachusetts 02140
10. PROGRAM ELEMENT NO.
EHE624B
11. CONTRACT/GRANT NO.
68-03-2198
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA-ORD
is. SUPPLEMENTARY NOTES Vol. J.J.J.-X, fcrA-oUU/ /-/b-U64c through EPA-600/7^7o=U34j , and VII-
XV, EPA 600/7-76-0341 through EPA-600/7-76-034o, refer to studies of other industries
as noted below; Vol I, EPA-600/7-76-034a is the Industry Summary Report and Vol II,
16. ABSTRACT
EPA-600/7-76-034b is the Industry Priority Report.
This study assesses the likelihood of new process technology and new practices being
introduced by energy intensive industries and explores the environmental impacts of
such changes.
Specifically Vol. XI deals with the glass industry and examines five alternatives:
(1) coal gasification, (2) direct coal firing, (3) electric melting, (4) coal, hot
gas regeneration, and (5) batch preheating in terms of their impact on relative
process economics and their environmental/energy consequences. Vol. III-X and
XII-XV deal with the following industries: iron and steel, petroleum refining, pulp
and paper, olefins, ammonia,,aluminum, textiles, cement, chlor-alkali, phosphorus
and phosphoric acid, copper and fertilizers. Vol. I presents the overall summation
and identification of research needs and areas of highest overall priority. Vol. II,
prepared early in the study, presents and* describes the overview of the industries
considered and presents the methodology used to select industries.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Energy: Bollution; Industrial Wastes;
Glass; Coal Gasification •
fenufacturing Processes;
Energy Conservation;
Natural gas; Glass -making
Direct firing; Preheating
13B
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (This Report)
unclassified
21. NO. OF PAGES
20. SECURITY CLASS (This page)
unclassified
22. PRICE
EPA Form 2220-1 (9-73)
111
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