EPA
TVA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-81-170
October 1981
Tennessee Valley
Authority
Office of Power
Energy Demonstrations
and Technology
Muscle Shoals Al 35660
TVA/OP/EDT-81/34
Economics of Ash
Disposal at Coal-fired
Power Plants
Interagency
Energy/Environment
R&D 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 nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine 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
8. "Special" Reports
9. Miscellaneous Reports
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 sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses 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 environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-81-170
TVA/OP/EDT-81/34
October 1981
Economics of Ash Disposal at
Coal-fired Power Plants
by
P.M. Kennedy, A.C. Schroeder, and J.D
TVA, Office of Power
Division of Energy Demonstrations and T
Muscle Shoals, Alabama 3566
EPA Interagency Agreement No. D9-E721 -Bl
EPA Project Officer: Julian W. Jo
Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
Research Triangle Park, NC 277' 1
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
. Veitch
ichnology
es
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DISCLAIMER
This report was prepared by the Tennessee Valley Authority and has been
reviewed by the Office of Environmental Engineering and Technology,
U.S. Environmental Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views and policies
of the Tennessee Valley Authority or 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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ABSTRACT
The comparative economics of utility ash disposal by five conceptual
design variations of ponding and landfill were evaluated for a 500-MW power
plant producing 5 million tons of ash over the life-of-project. For a basic
pond disposal without water reuse* the total capital investment from hopper
collection through one-mile sluicing and pond disposal is $52/kW (1982$).
Comparable total system investment using trucking to a landfill is $30/kW.
All disposal site construction costs were fully capitalized in both cases and
this convention affects the comparison of annual revenue requirements. First-
year annual revenue requirements for the ponding system are 1.85 mills/kWh
(1984$), while those for the landfill system are lower at 1.66 mills/kWh. On
the other hand, levelized annual revenue requirements are 2.26 mills/kWh and
2.42 mills/kWh respectively. Disposal site costs are the major element in all
types of disposal and constituted the major difference in cost between pond
and landfill disposal. Reuse of sluicing water and additional provisions for
the disposal of self-hardening (high calcium oxide) ash added relatively
little to costs.
ill
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CONTENTS
Abstract iii
Figures ................... ... vii
Tables ix
Executive Summary S-l
Introduction 1
Background 3
Utility Coal Use and Coal Characteristics 3
Utility Boiler Design . 4
Coal Mineral Matter and Coal Ash 8
Fly Ash 9
Fly Ash Collection 10
Bottom Ash 12
Ash Handling 13
Fly Ash 13
Bottom Ash ....... ..... 13
Ash Disposal ..... 14
Waste Disposal Regulations ............ 16
Leachate ...................... . 19
Ash Utilization 19
Premises ............................... 23
Design Premises ...... 23
Environmental Standards ........... 23
Fuel 23
Flue Gas Composition ...... ........... 24
Power Plant 25
Ash Collection and Transportation ...... 25
Disposal Sites ..... ....... 26
Mobile Equipment .................... 28
Economic Premises .......... ......... 28
Capital Investment Estimates .......... .. 31
Annual Revenue Requirements 34
Systems Estimated .... ............. 38
Base Case 1 - Direct Ponding of Nonhardening Ash Without Water
Reuse 38
Fly Ash Collection 49
Bottom Ash Collection 50
Ash Transportation 50
Ash Ponds 50
v
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Base Case 2 - Direct Ponding of Nonhardening Ash With Water Reuse * 51
Ash Ponds 63
Base Case 3 - Holding Ponds and Landfill for Nonhardening Ash . * . 63
Ash Ponds 78
Ash Removal and Transportation .................. 78
Landfill 78
Base Case 4 - Direct Landfilling of Nonhardening Ash 79
Fly Ash Collection 79
Bottom Ash Collection 95
Ash Transportation ................. 95
Landfill 95
Base Case 5 - Direct Landfilling of Self-Hardening Ash .. 96
Ash Collection 112
Ash Transportation 112
Landfill 112
Results 113
Direct Capital Investment ........ ....... 113
Equipment Costs ... ...... 113
Installed Equipment Costs 115
Total Capital Investment 121
Annual Revenue Requirements .. ............. 126
Modular Capital Investment and Annual Revenue Requirements 129
Modular Costs by Type of Equipment and Facility Area ....... 129
Modular Costs by Process Area 134
Case Variations .139
Trucking Distance to Disposal Site 139
Ash Collection Rate 141
Land Cost 143
Ash Utilization . 143
Comparison With TVA Ash Disposal Costs ..... 148
Equipment Cost Comparisons ................ 149
Operating and Maintenance Cost Comparison .. ...... 149
Comparisons Among Ash Disposal Studies ... 156
Conclusions 160
References 162
Appendix A..... 171
Appendix B . 183
vi
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FIGURES
S- 1 Utility coal consumption and ash production by geographical
region for 1977 and 1985 S- 3
S- 2 Effect of ash collection rate on costs, base cases 1 through
5 S-18
S- 3 TVA and base case 1 operating and maintenance ash disposal
costs ............... • S-22
1 Utility coal consumption and ash production by geographical
region for 1977 and 1985 5
2 Generalized pulverized coal-fired utility boiler . . 6
3 Utility coal consumption, ash production, and ash
utilization - 1950-1978 22
4 Pond dike construction details 27
5 Landfill construction details . 29
6 Truck requirement for ash transportation 30
7 Flow diagram. Base case 1, direct ponding of nonhardening ash
without water reuse ... 39
8 Disposal site. Base case 1, direct ponding of nonhardening
ash without water reuse ... ........... 40
9 Plot plan. Base case 1, direct ponding of nonhardening ash
without water reuse ..... 41
10 Flow diagram. Base case 2, direct ponding of nonhardening ash
with water reuse 52
11 Disposal site. Base case 2, direct ponding of nonhardening
ash with water reuse 53
12 Plot plan. Base case 2, direct ponding of nonhardening ash
with water reuse ......... ......... 54
13 Flow diagram. Base case 3, holding ponds and landfill for
nonhardening ash ........... ...... 64
14 Disposal site. Base case 3, holding ponds and landfill for
nonhardening ash ............ .... 65
15 Plot plan. Base case 3, holding ponds and landfill for non-
hardening ash 66
16 Flow diagram. Base case 4, direct landfill of nonhardening
ash 80
17 Disposal site. Base case 4, direct landfill of nonhardening
ash .................... 81
18 Plot plan. Base case 4, direct landfill of nonhardening ash . 82
19 Flow diagram. Base case 5, direct landfill of self-hardening
ash 97
20 Disposal site. Base case 5, direct landfill of self-hardening
ash 98
vii
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FIGURES (continued)
Number Page
21 Plot plan. Base case 5» direct landfill of self-hardening
ash 99
22 Modular costs by equipment and facility area .... 132
23 Effect of distance to disposal site on costs* base cases 3» 4*
and 5 140
24 Effect of ash collection rate on costs* base cases 1 through
5 142
25 Effect of pond and landfill volume on direct investment . . . 144
26 Effect of land costs on total costs* base cases 1 through 5 . 145
27 Effect of ash utilization on costs* base cases 1 through 5 . . 146
28 TVA and base case 1 operating and maintenance ash disposal
costs 153
viii
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TABLES
Number
S- 1 Cost of Delivered Equipment • S-8
S- 2 Typical Distribution of Pond and Landfill Construction Costs . S- 9
S- 3 Pond and Landfill Construction Costs S-10
S- 4 Summary of Capital Investments ................ S-ll
S- 5 Major Cost Elements in Capital Investments S-12
S- 6 Summary of Annual Revenue Requirements .. S-13
S- 7 Major Cost Elements in Annual Revenue Requirements S-14
S- 8 Modular Capital Investment by Process Area S-15
S- 9 Modular Annual Revenue Requirements by Process Area S-16
S-10 Installed Cost of Two TVA Ash Disposal Systems . S-21
1 Ash Collection. Utilization, and Disposal, 1977 . 20
2 Coal Compositions ...................... 24
3 Base Case Flue Gas Compositions and Flow Rates 25
4 Pond and Landfill Unit Costs 32
5 Percentage Factors for Proportioned Investments . . 33
6 Projected 1984 Unit Costs for Raw Materials, Labor, and
Utilities 34
7 Material Balance Base Case 1 - Direct Ponding of Nonhardening
Ash Without Water Reuse 42
8 Equipment List, Description, and Material Cost Base Case 1 -
Direct Ponding of Nonhardening Ash Without Water Reuse .... 44
9 Material Balance Base Case 2 - Direct Ponding of Nonhardening
Ash With Water Reuse 55
10 Equipment List, Description, and Material Cost Base Case 2 -
Direct Ponding of Nonhardening Ash With Water Reuse 57
11 Material Balance Base Case 3 - Holding Ponds and Landfill for
Nonhardening Ash .......... 67
12 Equipment List, Description, and Material Cost Base Case 3 -
Holding Ponds and Landfill for Nonhardening Ash 70
13 Material Balance Base Case 4 - Direct Landfill of Nonhardening
Ash 83
14 Equipment List, Description, and Material Cost Base Case 4 -
Direct Landfill of Nonhardening Ash ..... 86
15 Material Balance Base Case 5 - Direct Landfill of Self-
Hardening Ash 100
16 Equipment List, Description, and Material Cost Base Case 5 -
Direct Landfill of Self-Harden ing Ash 103
17 Costs of Delivered Equipment ............ 114
18 Installed Process Equipment Direct Capital Investment - Base
Case 1, Direct Ponding of Nonhardening Ash Without Water Re-
use ............................. 116
ix
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TABLES (continued)
Number Page
19 Installed Process Equipment Direct Capital Investment - Base
Case 2, Direct Ponding of Nonhardening Ash With Water Reuse . 117
20 Installed Process Equipment Direct Capital Investment - Base
Case 3, Holding Ponds and Landfill of Nonhardening Ash .... 118
21 Installed Process Equipment Direct Capital Investment - Base
Case 4, Direct Landfill of Nonhardening Ash ......... 119
22 Installed Process Equipment Direct Capital Investment - Base
Case 5, Direct Landfill of Self-Hardening Ash 120
23 Pond and Landfill Construction Costs ..... 122
24 Base Case Summaries of Capital Investments 124
25 Major Cost Elements in Capital Investment . 125
26 Base Case Summaries of Annual Revenue Requirements 127
27 Major Cost Elements in Annual Revenue Requirements ...... 128
28 Modular Capital Investment by Equipment and Facility Areas . . 130
29 Modular Annual Revenue Requirements by Equipment and Facility
Areas 131
30 Modular Capital Investment by Process Area .......... 136
31 Modular Annual Revenue Requirements by Process Area ..... 137
32 Installed Cost of Ash Disposal Systems at TVA Power Plant A . 150
33 Installed Cost of Ash Disposal Systems at TVA Power Plant B . 151
34 Comparison of Base Case 1 With TVA Installed Costs of Ash Dis-
posal Systems .. ............. 152
35 Base Case 1 Operating and Maintenance Costs Comparative
Basis 155
36 Comparison of Premises and Costs Among Ash Disposal Studies . 157
A- 1 Capital Investment Base Case 1» Direct Ponding of Nonhardening
Ash Without Water Reuse ............ 172
A- 2 Annual Revenue Requirements Base Case 1» Direct Ponding of
Nonhardening Ash Without Water Reuse ...... .. 173
A- 3 Capital Investment Base Case 2, Direct Ponding of Nonhardening
Ash With Water Reuse 174
A- 4 Annual Revenue Requirements Base Case 2» Direct Ponding of
Nonhardening Ash With Water Reuse ....... 175
A- 5 Capital Investment Base Case 3, Holding Ponds and Landfill of
Nonhardening Ash 176
A- 6 Annual Revenue Requirements Base Case 3» Holding Ponds and
Landfill for Nonhardening Ash 177
A- 7 Capital Investment Base Case 4, Direct Landfill of Nonhard-
ening Ash 178
A- 8 Annual Revenue Requirements Base Case 4, Direct Landfill of
Nonhardening Ash 179
A- 9 Capital Investment Base Case 5i Direct Landfill of Self-
Hardening Ash ..... ....... 180
A-10 Annual Revenue Requirements Base Case 5. Direct Landfill of
Self-Hardening Ash ...... 181
B- 1 Modular Capital Investment by Type of Equipment Base Case 1,
Direct Ponding of Nonhardening Ash Without Water Reuse .... 184
x
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TABLES (continued)
Number
B- 2 Modular Annual Revenue Requirements by Type of Equipment Base
Case 1, Direct Ponding of Nonhardening Ash Without Water Re-
use 185
B- 3 Modular Capital Investment by Type of Equipment Base Case 2,
Direct Ponding of Nonhardening Ash With Water Reuse 186
B- 4 Modular Annual Revenue Requirements by Type of Equipment Base
Case 2, Direct Ponding of Nonhardening Ash With Water Reuse . 187
B- 5 Modular Capital Investment by Type of Equipment Base Case 3»
Holding Ponds and Landfill of Nonhardening Ash 188
B- 6 Modular Annual Revenue Requirements by Type of Equipment Base
Case 3» Holding Ponds and Landfill of Nonhardening Ash .... 189
B- 7 Modular Capital Investment by Type of Equipment Base Case 4,
Direct Landfill of Nonhardening Ash 190
B- 8 Modular Annual Revenue Requirements by Type of Equipment Base
Case 4, Direct Landfill of Nonhardening Ash 191
B- 9 Modular Capital Investment by Type of Equipment Base Case 5,
Direct Landfill of Self-Hardening Ash 192
B-10 Modular Annual Revenue Requirements by Type of Equipment Base
Case 5, Direct Landfill of Self-Hardening Ash 193
B-ll Modular Capital Investment by Process Area Base Case 1,
Direct Ponding of Nonhardening Ash Without Water Reuse .... 194
B-12 Modular Annual Revenue Requirements by Process Area Base Case
1, Direct Ponding of Nonhardening Ash Without Water Reuse . . 195
B-13 Modular Capital Investment by Process Area Base Case 2t Direct
Ponding of Nonhardening Ash With Water Reuse 196
B-14 Modular Annual Revenue Requirements by Process Area Base Case
2, Direct Ponding of Nonhardening Ash With Water Reuse .... 197
B-15 Modular Capital Investment by Process Area Base Case 3, Hold-
ing Ponds and Landfill of Nonhardening Ash 198
B-16 Modular Annual Revenue Requirements by Process Area Base Case
3, Holding Ponds and Landfill of Nonhardening Ash 199
B-17 Modular Capital Investment by Process Area Base Case 4, Direct
Landfill of Nonhardening Ash 200
B-18 Modular Annual Revenue Requirements by Process Area Base Case
4, Direct Landfill of Nonhardening Ash ..... 201
B-19 Modular Capital Investment by Process Area Base Case 5. Direct
Landfill of Self-Hardening Ash 202
B-20 Modular Annual Revenue Requirements by Type of Equipment Base
Case 5, Direct Landfill of Self-Hardening Ash 203
XI
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ACKNOWLEDGEMENTS
This study benefited from technical, design, equipment, and cost
information provided by TVA personnel and by a number of commercial,
technical, and trade organizations. This assistance is gratefully
acknowledged. In addition to guidance and assistance by Julian W. Jones, EPA
project officer, special acknowledgement is extended to The Allen-Sherman-Hoff
Company (James J. Murphy and Robert Fitz-Maurice)» Combustion Engineering,
Inc. (Joseph Fleming, B. M. Minor, Anthony Cozzo, and Douglas Rody), United
Conveyor Corp. (R. S. Shah and Robert Kollar) and its representative, Gerrard
Associates, Inc. (B. Frank Stamey), Hydro-Ash Corp. (Anthony J. Brajdic), and
to The National Ash Association (John H. Faber).
XII
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ECONOMICS OF ASH DISPOSAL AT COAL-FIRED POWER PLANTS
EXECUTIVE SUMMARY
INTRODUCTION
The use of coal in steam-electric power plants produces a sizable
quantity of ash that presents an increasingly complex disposal problem. Coal
cleaning and ash utilization tend to reduce the quantity of ash to be disposed
of but other factors continue to increase the amount that must be discarded in
an environmentally acceptable manner. Such factors include the steadily
increasing amount of steam coal burned, the growing reliance on higher ash
coals, and the increasing efficiency required in ash collection. In 1978 the
electric utility industry burned almost 500 million tons of coal, generating
almost 70 million tons of ash.
Conventional ash disposal has been mostly by sluicing to nearby ponds
without reuse of the water. This practice has become increasingly
unacceptable and expensive because of the large land requirements, the
unavailability of suitable sites, environmental effects, higher land cost, and
disposal regulations. As a result, dry or moist ash transportation and
landfill disposal are becoming more common. In a number of cases ponds are
used as dewatering and holding sites, followed by conveyance to a landfill.
This study examines the economics of five combinations of these disposal
practices. The evaluations are based on technical and economic premises
chosen for use in EPA-TVA studies. The results are arranged in modular form
to facilitate cost comparisons. In addition, the estimated economics are
compared with actual costs of ash disposal at TVA coal-fired power plants.
Five base case disposal processes are evaluated:
Base case 1: Direct sluicing of nonhardening (low calcium oxide)
fly ash and bottom ash to separate ponds one mile from the power
plant without water reuse.
Base case 2: The same as base case 1 with water return, treatment,
and reuse.
Base case 3: Temporary ponding of nonhardening fly ash and bottom
ash in 5-year-capacity ponds one-fourth mile from the power plant,
followed by removal, dewatering, and truck transportation to a
single landfill three-fourths of a mile from the ponds.
S-l
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Base case 4: Disposal of nonhardening ash in separate landfills one
mile from the power plant with dry collection of fly ash, dewatering
of bottom ash, and truck transportation.
Base case 5: The same as base case 4 with self-hardening fly ash
and provisions to prevent its hardening before disposal.
BACKGROUND
Most large utility boilers are fired with finely pulverized coal which is
pneumatically injected into the boiler along with a portion of the combustion
air. The coal burns at temperatures approaching 3,000°F while suspended in
the highly turbulent combustion gases. Most of the ash solidifies in
suspension as fine particles, a portion of which is carried out of the furnace
in the flue gas as fly ash. The rest falls to the bottom of the furnace as
bottom ash. In the most prevalent type of utility boiler, a so-called dry-
bottom boiler, about 80% of the total ash is fly ash and 20% is bottom ash. A
small portion of the fly ash settles in the boiler economizer and air heater
but the majority remains suspended in the gas and must be collected downstream
of the air heater. In dry-bottom boilers bottom ash falls through one or more
throats in the bottom of the furnace as solid particles. The ash falls into
water-cooled bottom ash hoppers with sloping sides and crushers at the ash
outlet.
Fly ash is a gritty powder composed of aluminum and iron silicates and
oxides along with numerous minor and trace components. Most of the particles
are in the size range of 0.1 to 0.01 mm although some range upward to over 1
mm in size and downward to submicrometer sizes. Fly ash has a bulk density of
35 to about 100 Ib/ft^, depending on the degree of compaction. In many
engineering properties it can be compared to a silty clay. In chemical
composition it is a pozzolan, requiring only calcium oxide and water to
undergo reactions such as occur in the setting of a hydraulic cement. Some
western coals, in fact, contain sufficient free calcium oxide to produce a
self-hardening fly ash that affects handling and disposal practices. Bottom
ash is similar in gross composition but coarser and denser than fly ash. In
texture and engineering properties it can be compared to a sandy gravel. It
seldom has pozzolanic or self-hardening properties.
Utility ash production has a highly variable geographical distribution
because of the regional variations in use of coal for electricity generation.
As shown in Figure S-l, the major portion of utility ash has been produced in
the central tier of states. By 1985, however, increased use of coal by
utilities in the West and Southwest is projected to shift this production
westward.
Most of the ash utilized is used for construction fill and concrete
additives. Utilization has expanded from 12% of the ash collected in 1966 to
24% in 1978. Because of the increase in ash production, however, the quantity
of ash disposed of has also increased at about 6% per year during the same
period.
S-2
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456789
REGION
Figure S-l. Utility coal consumption and ash production by
geographical region for 1977 and 1985.
(Derived from Ref. 10)
S-3
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The most common method of disposal, ponding of sluiced ash, is practiced
by more than half of the U.S. utilities, especially by those east of the
Mississippi River. In most cases, fly ash and bottom ash are sluiced
separately or together to final disposal ponds. Many ponds take advantage of
the natural topography and few have liners. In some cases, the ash is removed
and landfilled to extend pond life. Some utilities use dry handling and
landfilling for fly ash and temporary or permanent ponding for bottom ash. In
lieu of temporary ponds, bottom ash may be dewatered mechanically.
Landfills are often chosen because of a shortage of nearby land for
construction of ponds or of water for sluicing. They range from structured
constructions to use of convenient depressions or excavations. Landfill
management ranges from ash dumping with incidental spreading and compaction to
well organized control of critical moisture levels and vibratory compaction.
PREMISES
The ash disposal evaluations included in this study are based on premises
established in 1979-1980 for use in EPA-TVA economic evaluations.
Design Premises
The power plant basis is a new north-central, 500-MW, pulverized-coal-
fired, dry-bottom power unit with a full-load operating schedule of 5,500
hr/yr over a 30-year life. The heat rate is 9,500 Btu/kWh. Two coals are
evaluated, an eastern bituminous coal with a heating value of 11,700 Btu/lb
containing 15.1% ash as fired and a western coal with a heating value of 9,700
Btu/lb containing 9.7% ash as fired. The eastern coal ash is assumed to be
nonhardening when wet. The western coal is assumed to contain sufficient
reactive calcium oxide to be self-hardening. For both coals 80% of the ash is
emitted as fly ash and the remainder is bottom ash. The fly ash removal,
mostly by an electrostatic precipitator (ESP), meets the emission level of the
1979 new source performance standards (NSPS), i.e., 0.03 Ib/MBtu.
The ash disposal systems include all ash collection, handling, and
disposal requirements, including bottom ash and fly ash hoppers. Ash hoppers
are included in both capital investment and annual revenue requirements
because the operation of the hoppers is a part of the overall disposal
operations. Disposal sites include area for topsoil storage and operational
facilities. Square earthen-diked clay-lined ponds constructed of onsite
material and square area-type landfills with a clay base are used. Provisions
for runoff control and reclamation are included. All disposal sites are sized
for the 30-year life of the power unit.
Economic Premises
The evaluations are based on a 1981-1983 construction period and a 1984
startup. 1982 costs are used for capital investment and 1984 costs are used
for annual revenue requirements.
Capital investment comprises direct investment, indirect investment,
contingency, and other capital investment. Direct investment consists of the
S-4
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installed cost of equipment and a 4% allowance for services, utilities, and
miscellaneous items. Indirect investment is factored based on direct
investment.
The annual revenue requirements consist of direct and indirect costs
comprising operating and maintenance costs and capital charges. The operating
and maintenance costs are first-year costs and the capital charges are
levelized over the life of the project. Direct costs for labor, utilities,
maintenance, and analyses reflect the operating schedules within the plant.
Indirect costs consist of a plant and administrative overhead cost of 60% of
conversion costs less utilities and a levelized annual capital charge of 14.7%
of total capital investment. No byproduct marketing credit is assumed.
Levelized annual revenue requirements are the sum of levelized operating and
maintenance costs and levelized capital charges.
SYSTEMS ESTIMATED
Base Case 1 - Direct Ponding of Nonhardening Ash Without Water Reuse
Ash is pneumatically collected from the economizer, air-heater, and ESP
hoppers by twin hydraulic exhauster systems sized to operate 50% of the time.
The hoppers have a 12-hour storage capacity. The economizer ash hoppers are
uninsulated and are thermally isolated from the hot flue gas by a throat and
chute. The air-heater hoppers are insulated and the ESP hoppers are heat
traced and insulated. Two hydraulic exhausters discharge the air-ash-water
mixtures to an air separator. The ash-water slurry at 7.7% solids flows by
gravity from the elevated air separator through a 1-mile-long, 12-inch ID,
schedule 80, carbon steel pipeline to the pond. A spare slurry pipeline is
provided. Operation of the fly ash collecting system is nominally automatic
but an operator oversees it on a 24 hr/day basis.
Bottom ash is collected in a double-vee bottom ash hopper with a 12-hour
capacity. The upper section is lined with 9-inch-thick monolithic refractory
and the bottom slopes are protected by a 6-inch-thick lining. Water overflows
the seal trough on a continuous basis to wet the refractory lining. Each vee
section has two double-roll grinders with a 2-inch roll spacing. The ash is
sluiced through the grinders into one of two centrifugal slurry pumps (one
pump is a spare). The 7.7% solids ash slurry is pumped through a 1-mile-long,
8-inch ID, basalt-lined pipeline to the bottom ash pond. A spare slurry
pipeline of schedule 80 carbon steel is provided. Each pipeline has an
agitator near its midpoint for reslurrying the ash-water mixture. The system
is designed to operate about 2 hours each 8-hour shift.
The fly ash and bottom ash ponds are situated side by side at the
disposal site. The overflow water, if above pH 9, is neutralized with
sulfuric acid from an automatic pH control unit and the effluent water is
sampled by an automatic sampler before discharge to the river.
Base Case 2 - Direct Ponding of Nonhardening Ash With Water Reuse
Base case 2 is identical to base case 1, except for the return and reuse
of pond overflow water. The water is pumped from the disposal site through a
S-5
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pipeline to a surge tank at the power plant from which it is used for fly ash
and bottom ash collection and conveyance. A lime-soda softener at the
disposal site controls gypsum hardness in the returned water to minimize
scaling.
Base Case 3 - Holding Ponds and Landfill for Nonhardening Ash
In base case 3, the fly ash and bottom ash collection systems are
identical to those of base case 1. The conveyance systems are similar to
those of base case 1 but the distance to the ponds is one-fourth mile instead
of one mile. For these conditions, the hydraulic exhausters and air separator
in base case 3 are situated at a lower elevation and require somewhat lower
pressure in the supply water. A jet pump is used in place of a centrifugal
pump for bottom ash conveyance.
The fly ash and bottom ash ponds of base case 3 are similar to those of
base case 1» but they are sized for a 5-year capacity. Ash from both ponds is
removed and hauled in 20-yd^-capacity trucks to a common (fly ash plus
bottom ash) landfill with a 25-year capacity.
Bottom ash is removed from the pond with track-type end loaders. Fly ash
is pumped from the pond by a floating dredge to an adjoining drainage basin
where it drains to 75% solids. The water returns to the fly ash pond. The
drained fly ash is removed with front-end loaders. Dump trucks with a 20-
yd^ capacity are used to transport the ash to the common landfill. Trucks
and landfill equipment operate 16 hrs/day.
Base Case 4 - Direct Landfilling of Nonhardening Ash
In base case 4 the fly ash is collected dry. moistened, and trucked to a
landfill. Bottom ash is dewatered mechanically and trucked to a separate
landfill. ESP ash and economizer-air heater ash are collected in a separate
vacuum system and stored dry in a separate silo. A common vacuum source in
the form of lobe-type mechanical exhausters is used. The ash is separated
from the conveying air in centrifugal collectors and a bag filter. With the
separate collecting systems, dry ESP ash is available for utilization,
uncontaminated by economizer and air heater ash, which is coarser and may
contain more carbon, making it less suitable for some uses. At the outlet of
each ash storage silo, a high-capacity moisturizer, consisting of a screw
conveyor with water sprays, increases the moisture content of the ash to 10%
water for dust control and delivers it to 20-yd3-capacity dump trucks.
Bottom ash is sluiced from the bottom ash hoppers, as in base case 1, and
pumped one-eighth mile in a basalt-lined slurry pipeline to dewatering bins.
Two dewatering bins alternate in operation. Water is recirculated to the
bottom ash hopper and small streams supply the fly ash moisturizers. Drained
bottom ash from the dewatering bins is hauled in 20-yd3-capacity dump trucks
to the bottom ash landfill.
The fly ash and bottom ash landfills are constructed and operated
similarly to the common landfill in base case 3. At the fly ash landfill,
water is added to obtain an optimum moisture level of 17% for vibratory
compaction. The bottom ash is assumed to have an optimum moisture level of
10%, the moisture level at which it is removed from the dewatering bins.
S-6
-------
Base Case 5 - Direct Landfilling of Self-Hardening Ash
Base case 5 duplicates base case 4 except in ash quantity and the self-
hardening nature of the fly ash. Because of its self-hardening property, the
fly ash is hauled dry in covered trucks to the fly ash landfill. Due to
differences in ash content and heating value, the coal for base case 5
contains only 77% of the ash tonnage in the other base cases. This difference
is reflected in equipment sizes.
Trucks for hauling dry fly ash to the landfill have covered 20-yd^-
capacity beds and onboard provisions for dust control when dumping. Each
truck has a skirted tailgate, so that when the bed is raised for dumping, ash
falls within the skirted confines. Water nozzles, supplied by an onboard
water tank and pump, are mounted within the skirted section and spray the ash
for dust control during unloading. Separate tank trucks add additional water
for ash compaction. Bottom ash from the dewatering bins is transported to the
landfill in a 7-yd^-dump truck.
RESULTS
In addition to overall capital investment and annual revenue
requirements, modular costs are developed by functional area.
Direct Capital Investment
Equipment costs are summarized in Table S-l. These uninstalled costs do
not include slurry pipelines, which are covered in the piping category, or
ponds, which are costed separately. Relative to the quantity of ash handled,
the bottom ash equipment is more than twice as expensive as the fly ash
equipment. The increase in equipment costs from base case 1 to case 2 is due
entirely to return water facilities. Base case 3 has slightly lower process
equipment costs because smaller pumps are used for the shorter pumping
distance. However, in base case 3 mobile equipment comprises about one-half
of the total equipment costs.
Process equipment costs in base case 4 are almost four times those of
base case 1 because of the more elaborate collection and storage of dry fly
ash and the mechanical dewatering of bottom ash. Mobile equipment is less
costly in base case 4 than in base case 3, which includes ash retrieval from
the ponds. Base case 5 has higher mobile equipment costs than base case 4
because of the need for separate fly ash trucks with covered beds and
moisturizing equipment.
The construction costs for ponds and landfills are shown in Table S-2.
They represent separate full-life ponds and separate full-life landfills for
the same ash tonnages. The costs represent only the disposal site, without
land, mobile equipment, or other conveying provisions, or allowance for
services, utilities, and miscellaneous needs.
S-7
-------
TABLE S-l. COST OF DELIVERED EQUIPMENT
1982 k$
Base case:
Fly Ash
Hoppers
Process equipment
Vehicles
123
421 421 421
341 484 348
0 0 899
4
421
1,154
545
5
356
934
598
Subtotal fly ash 762 905 1,668 2,120 1,888
Bottom Ash
Hoppers 352 352 352 352 310
Process equipment 147 183 132 674 604
Vehicles 0 0 309. 137 136
Subtotal bottom ash 499 535 793 1,163 1,050
Total Ash
Hoppers 773 773 773 773 666
Process equipment 488 667 480 1,828 1,538
Vehicles 0 0 1,208 682 734
Total 1,261 1,440 2,461 3,283 2,938
S-8
-------
TABLE S-2. TYPICAL DISTRIBUTION OF POND AND LANDFILL CONSTRUCTION COSTS
Land clearance
Excavation, soil storage
Dike construction
Liner installation
Catchment ditch, basin
Ditches, roads, fence, etc.
Reclamation
Total
Separate ponds,
base case 1
1982 k$ %
Separate landfills,
base case 4
343
3,975
2,309
1,222
475
2,312
3
37
22
11.5
4.5
22
1982 k$
128
439
556
295
241
774
10,636 100
2,433
7
/o
5
18
23
12
10
32
100
Pond/landfill volume,& Myd3
6.93
4.21
a. Based on 171,600 tons/yr of ash.
Both the total costs and the profiles of cost differ markedly for the two
cases. In landfills the compacted ash volume is about 60% of that of settled
ash in ponds. Also, it is practical to construct landfills, at least on level
terrain, at a considerably greater height than ponds. For both ponds and
landfills, the most costly requirement is the movement and placement of
earth. For ponds this constitutes about two-thirds of the total cost. The
earthmoving costs for landfills are much less because dikes are not required
and excavation is minimal.
Pond and landfill construction costs are summarized in Table S-3 for the
five base cases. The 5-year ponds of base case 3 accommodate only 17% of the
ash tonnage of the 30-year ponds but their cost is 30% of the 30-year ponds,
reflecting an economy of size. The difference in landfill costs between base
cases 4 and 5 is due principally to ash tonnage.
S-9
-------
TABLE S-3. POND AND LANDFILL
CONSTRUCTION COSTS
1982 k$
Ponds Landfills
Total
Base
Base
Base
Base
Base
case
case
case
case
case
1
2
3
4
5
10
10
3
.636
,636
,142
-
"
1
2
2
.
-
,863
,433
,037
10
10
5
2
2
,636
,636
,005
,433
,037
Total Capital Investment
Total capital investment is summarized in Table S-4. The difference
between base cases 1 and 2 is for water reuse facilities. In base case 3, the
capital investment is lower because the pond-landfill costs, which predominate
in direct investment, are less than half those of the prior cases. They more
than offset the mobile equipment costs for ash retrieval from the ponds.
Since base case 4 has landfills without ponds, its capital investment is
lower. Base case 5 has a still lower capital investment because of its
smaller ash tonnage.
In cost per ton of ash handled the capital investments are lowest for
direct landfill (base case 4) and highest for direct ponding (base cases
1 and 2). Also, relative to material handled, the bottom ash investment is
1.5 to 2.2 times that for fly ash. The higher values represent mechanical
dewatering of bottom ash in base cases 4 and 5.
Table S-5 shows the distribution of capital investment among the major
functional areas. In all cases the disposal site constitutes the largest
element, but it is a much lower percentage of total costs in landfill cases.
S-10
-------
TABLE
S-4. SUMMARY OF CAPITAL
1982 k$
Base Case 1
Fly ash
Bottom ash
Total
Base Case 2
Fly ash
Bottom ash
Total
Base Case 3
Fly ash
Bottom ash
Total
Base Case 4
Fly ash
Bottom ash
Total
Base Case 5
Fly ash
Bottom ash
Total
Uni
Total capital
investment, k$
18,880
6,980
25,860
19,800
7,220
27,020
11,630
4,500
16,130
9,650
5,100
14,750
8,190
4,460
12,650
S-ll
INVESTMENTS
; capital
$/kW
37.7,
14.0
51.7
39.6
14.4
54.0
23.3
9.0
32.3
19.3
10.2
29.5
16.4
8.9
25.3
investment
$/ annual
ton ash
138
203
151
144
210
157
85
131
94
70
149
86
78
170
96
-------
TABLE S-5. MAJOR COST ELEMENTS IN
CAPITAL INVESTMENTS
Percentage of total
capital investment
Base case: 12345
Cost Element
Ash collection 8 8 13 16 15
Ash transportation 7 7 10 18 18
Disposal site 43 41 35 20 21
Water treatment and recycle - 3 1 3 3
Proportioned costsa 34 34 34 38 38
Land 87755
a. Indirect investment• contingency, other capital
investment, working capital.
Annual Revenue Requirements
Annual revenue requirements are shown in Table S-6. Base case 5 has the
lowest annual revenue requirements because of the lowest quantity of ash. In
terms of cost per ton of ash it is the highest. Base case 4, with mechanical
dewatering of bottom ash and trucking of fly ash and bottom ash to separate
landfills, has lower annual revenue requirements than base case 1 with
conventional pond disposal. The reuse of pond water in base case 2 adds
0.13 mill/kWh or about 7% to the costs. Base case 3 with its pond-landfill
combination has annual revenue requirements only 3% higher than base case 1
with ponds, but 14% higher than base case 4 with landfills.
Major elements of annual revenue requirements are shown in Table S-7. In
all cases, the capital charges are dominant; ranging from 47% of the total
annual revenue requirements for a landfill process to 75% for a pond process.
Maintenance, at 9% to 12%, is important in all cases, and labor is high in the
cases with mobile equipment. As a result, overheads are also high in the
mobile equipment cases.
S-12
-------
TABLE S-6. SUMMARY OF ANNUAL REVENUE REQUIREMENTS
1984 k$
Base Case 1
Fly ash
Bottom ash
Total
Base Case 2
Fly ash
Bottom ash
Total
Base Case 3
Fly ash
Bottom ash
Total
Base Case 4
Fly ash
Bottom ash
Total
Base Case 5
Fly ash
Bottom ash
Total annual
revenue require-
ments, k$
3,570
1,510
5,080
3,840
1,600
5,440
3,850
1,400
5,250
2,950
1,600
4,550
2,740
1,570
Unit annual revenue
requirements
Mills /kWh
1.30
0.55
1.85
1.40
0.58
1.98
1.40
0.51
1.91
1.08
0.58
1.66
1.00
0.57
$/dry ton ash
26.0
44.1
29.6
28.0
46.5
31.7
28.0
40.8
30.6
21.5
46.6
26.5
26.1
60.0
Total
4,310
1.57
32.8
S-13
-------
TABLE S-7. MAJOR COST ELEMENTS IN
ANNUAL REVENUE REQUIREMENTS
Percentage of total
annual revenue requirements
Base case: 12 345
Labor
Process reagents
Utilities
Electricity
Diesel fuel
Maintenance
Sampling and analysis
Dredging
Overheads
Capital charges
4
-
1
-
10
1
—
9
75
4
-
2
-
10
1
—
9
73
17
-
1
4
9
1
4
19
45
17
-
1
3
12
1
—
18
47
20
2
-
3
11
1
—
20
43
Modular Costs
Modular capital investments by process area are shown in Table S-8 and
modular annual revenue requirements by process area are shown in Table S-9.
In all cases, the capital investment for the disposal site is the largest
cost, ranging from 36% for direct landfill to 71% for direct ponding.
Similarly, in annual revenue requirements, the disposal site is the most
costly process area, ranging from 37% for direct landfill to 60% for direct
ponding. Ash collection costs show little variation due to method. Truck
transportation costs are 50% to 60% higher than pipeline conveyance. Water
treatment and recycle costs are lowest in base case 1 and highest in
base case 2, which included return and reuse of the water.
To some extent, pond and landfill disposal sites have offsetting annual
revenue requirements. The cost of operating the pond disposal site in base
case 1 is 80% higher than the cost for operating the landfill site in base
case 4. When the ash transportation costs are included, however, base case 1,
with its high-cost pond and low-cost transportation, is only 28% more
expensive than the low-cost landfill with its high-cost transportation.
Differences in water treatment costs further narrow the gap so that the total
annual revenue requirements of base case 1 are only 12% higher than those of
base case 4.
S-14
-------
TABLE S-8. MODULAR CAPITAL INVESTMENT BY PROCESS AREA
1982 k$
Collection
Base Case 1
Fly ash
Bottom ash
Total
7
fo
Base Case 2
Fly ash
Bottom ash
Total
7
/o
Base Case 3
Fly ash
Bottom ash
Total
%
Base Case 4
Fly ash
Bottom ash
Total
%
Base Case 5
Fly ash
Bottom ash
Total
%
2,337
1,524
3,861
15
2,337
1,524
3,861
14
2,340
1,481
3,821
23
2,734
1.524
4,258
29
2,272
1,304
3,576
28
Transportation
1,791
1,765
3,556
13
1,791
1,765
3,556
13
1,452
1,095
2,547
16
2,582
1,824
4,406
30
2,204
1,610
3,814
30
Disposal site
14,648
3.662
18,310
71
14,648
3,662
18,310
68
7,620
1.868
9,488
59
4,231
1,064
5,295
36
3,609
903
4,512
36
Water
treatment
and recycle Total
105
28
133
1
1,025
270
1,295
5
216
57
273
2
105
689
794
5
105
638
743
6
18,891
6,979
25,860
100
19,801
7,221
27,022
100
11,628
4,501
16,129
100
9,652
5,101
14,753
100
8,190
4,455
12,645
100
S-15
-------
TABLE S-9. MODULAR ANNUAL REVENUE REQUIREMENTS BY PROCESS AREA
1984 k$
Base Case 1
Fly ash
Bottom ash
Total
%
Base Case 2
Fly ash
Bottom ash
Total
%
Base Case 3
Fly ash
Bottom ash
Total
%
Base Case 4
Fly ash
Bottom ash
Total
%
Base Case 5
Fly ash
Bottom ash
Total
%
Collection
681
423
1,105
22
681
423
1,105
20
680
409
1,089
21
751
420
1,171
26
647
365
1,012
24
Transportation
385
442
827
16
380
440
821
15
1,219
474
1,692
32
798
535
1,333
29
747
494
1,241
29
Disposal site
2,451
615
3,065
60
2,451
615
3,065
57
1,837
456
2,294
44
1,348
350
1,698
37
1,285
324
1,609
37
Water
treatment
and recycle
54
34
88
2
330
116
446
8
112
62
174
3
57
296
354
8
57
387
444
10
Total
3,571
1,514
5,085
100
3,842
1,595
5,437
100
3,848
1,402
5,250
100
2,954
1,600
4,555
100
2,736
1,575
4,311
100
S-16
-------
Case Variations
Trucking distance, land cost* ash collection rate, and ash utilization
were evaluated to determine their effects on the cost of ash disposal.
Increasing trucking distance (at an average highway speed of 30 mph) in-
creases capital investment 20,000 $/mile for base case 3, 14,000 $/mile for
base case 4, and 9,000 $/mile for base case 5. For a distance of 50 miles,
the increase in ash disposal capital investment is 6%, 5%, and 4%,
respectively, compared with the 1-mile distance. The increase is a result of
the additional trucks required and varies among the cases because of the
different water contents (base case 3 versus base case 4) and ash quantities
(base case 4 versus base case 5).
Annual revenue requirements are affected by the additional direct operat-
ing costs of the vehicles such as labor, fuel, and maintenance as well as
additional capital charges and overheads. Annual revenue requirements
increase at rates of 23,000 $/mile for base case 3, 17,000 $/mile for case 4,
and 10,000 $/mile for base case 5. The increase in first-year annual revenue
requirements for ash disposal are 22%, 18%, and 12%, respectively, compared
with the 1-mile distance. As in capital investment, these costs are affected
by the different moisture contents and ash tonnages of the base cases.
Ash collection rates (representing different coal properties and
power plant operating conditions) were evaluated for each base case process,
at rates 24% above and 24% below the ash rate of base cases 1 through 4. The
low rate is the same as that of base case 5. The results (Figure S-2) show
slightly curved relationships between costs and ash rates but the
relationships are defined more clearly by cost-to-rate exponents of the
type: cost 1 = cost 2 (rate I/rate 2)exP. The exponents are:
Exponent for: Base cases 1.2 Base case 3 Base cases 4. 5
Capital investment 0.75 0.71 0.67
Annual revenue requirement 0.68 0.68 0.64
For both capital investment and annual revenue requirements, the lower
exponents for base cases 4 and 5, using landfills, mean that landfills have
slightly greater economy of scale than do the ponds in base cases 1 and 2.
Land costs of $1,000, $10,000, and $15,000 per acre, as compared with the
base case cost of $5,000 were evaluated. The effects on overall costs are
moderate. For example, increasing the cost of land from $5,000 per acre to
$15,000 per acre increases base case 1 capital investment by 15% and annual
revenue requirements by 11%.
The effects of utilizing 25% and 50% of the ash without changing the
proportions of fly ash and bottom ash disposed of were evaluated. Utilized
ash is assumed to be removed from the ponds in base cases 1 to 3 and from the
fly ash silos and dewatering bins in base cases 4 and 5 at no cost to the
utility. The main cost effects are in reduced trucking requirements and
reduced disposal site requirements. The percentage changes in capital
investment and annual revenue requirements are shown below.
S-17
-------
80,000
c°sts k
5.
-------
Percentage Capital investment
utilization oercentaee decrease
Base case 1:
Base case 2:
Base case 3:
Base case 4:
Base case 5:
25
50
25
50
25
50
25
50
25
50
14
30
14
29
10
17
9
16
11
16
Annual
revenue requirements
percentage decrease
12
26
11
25
9
18
9
18
10
18
Utilization results in larger savings in base cases 1 and 2 than in base
cases 3» 4» and 5. This difference is due to the much larger cost of ponds
compared with landfills.
COMPARISON WITH TVA ASH DISPOSAL COSTS
Information on actual costs of TVA ash disposal was used in performing
these evaluations. However, some data were not directly applicable because of
different time frames, accounting practices, designs, and economic bases. It
is possible, however, to compare certain aspects of the costs developed in
this study with actual ash disposal costs at TVA coal-fired power plants.
Eight TVA plants were selected for cost comparisons with the base case 1
conceptual design. The eight plants have dry-bottom pulverized-coal-fired
furnaces burning bituminous coal. They were constructed in the period 1951 to
1973. The average station capacity is 1,600 MW and the average unit capacity
is 260 MW. In 1978 the average yearly ash production was 563,000 tons per
plant. (In comparison, base case 1 represents a 500-MW power unit producing
171,600 tons of ash per year.) The bottom ash is typically sluiced from the
hoppers through clinker grinders and pumped through steel pipelines with
centrifugal pumps. Fly ash is typically removed from the flue gas with ESP's
or mechanical collectors and collected with vacuum systems using water
exhausters. It is sluiced to the ponds through steel pipes, either separately
or combined with the bottom ash. The water is not reused. The onsite ponds
differ in size, configuration, and construction technique and are situated
from a few hundred feet to over one mile from the power plants.
The most relevant comparison of base case 1 direct capital investment can
be made with the installed costs of ash disposal equipment for two power units
at two TVA plants constructed in 1963 and 1965. Indirect costs cannot be
readily compared because of differences in accounting and financial
practices. The base case 1 operating and maintenance costs can be compared
with TVA operating and maintenance costs for all eight of the TVA plants. The
TVA costs are also adjusted for size, pipeline length, and other factors as
discussed below.
S-19
-------
Equipment Cost Comparisons--
The costs of installed ash disposal equipment at the two TVA power plants
used and the nature of the adjustments needed for comparison with base case 1
are shown in Table S-10. The TVA cost adjustments consist of: (1) an
increase in the bottom ash hopper capacity from 8 to 12 hours, (2) an
adjustment in the pipelines to a one-mile length, basalt lining, and spare
provisions, (3) a size factor based on a cost-to-size exponent of 0.8, and
(4) an inflation factor. The ESP hopper costs are excluded from the base case
1 costs because they are not differentiated in the TVA ESP costs. As can be
seen in Table S-10, the comparable, generalized conceptual design costs are
within 5% to 10% of actual adjusted TVA costs for similar systems.
Operating and Maintenance Cost Comparison--
The operating and maintenance costs (excluding ponds) for ash disposal
from 1970 to 1978 at the eight TVA plants are shown in Figure S-3. Also shown
is the base case 1 operating and maintenance cost from the projected 1984
costs developed in this study and the 1978 TVA average cost projected to 1984
using the cost indexes discussed in the premises.
The TVA costs comprise the operating labor and the maintenance labor and
materials for removal of ash from the hoppers, sluicing to the ponds, pond
maintenance, and treatment of the discharge water. Costs for electricity are
not included. In 1978 the average TVA ash production rate per plant was
562,500 tons of ash, producing an average operating and maintenance cost of
$1.95 per ton. Projected to 1984 using the premise indexes, the costs become
$3.07 per ton.
The conceptualized base case 1 operating and maintenance costs, excluding
electricity, are $766,800, or $4.47 per ton in 1984 dollars based on 171,600
tons per year of ash. Assessment of the systems involved results in an appro-
priate size correction factor of 0.79. Applying this correction, the base
case 1 costs become $3.53 per ton in 1984 dollars.
Design differences other than plant size and ash tonnage lead to small or
offsetting differences in operation and maintenance cost. For example, a
reduction in length of slurry pipeline from 1 mile to 1/2 mile would lower
pipeline maintenance by $0.10 per ton of ash but greater ash dilution in the
TVA pipelines increases their size, and hence maintenance cost, by a similar
amount.
At $3.53 per ton of ash, the base case 1 cost for operation and
maintenance is 15% higher than the projected 1984 average TVA cost of $3.07
per ton of ash.
CONCLUSIONS
The most common current method of utility ash disposal, sluicing to a
permanent pond with no water recycle, has a higher capital investment (52
$/kW) and annual revenue requirements (1.85 mills/kWh) than landfill disposal
capital investment (30 $/kW) and annual revenue requirements (1.66 mills/kWh)
for the same power unit conditions.
S-20
-------
TABLE S-10. INSTALLED COST OF TWO TVA ASH DISPOSAL SYSTEMS
LO
I
Equipment
Bottom Ash
Hopper assembly
Disposal piping system
Water supply system
Total, bottom ash
Fly Ash
Handling system
Disposal piping system
Water supply system
Total, fly ash
Total
. , . a
Adjustments
8 to 12 hour capacity,
unit size, inflation
Extension to 1 mile,
basalt lining, share
of spare line, unit
size, inflation
Unit size, inflation
Inclusion of hopper
insulation, unit size,
inflation
Extension to 1 mile,
share of spare line,
unit size, inflation
Unit size, inflation
Plant A
TVA cost, Adjusted cost,
k$ (1963) k$ (1982)
290 932
26 527
20 54
1,513
123 457
104 773
79 214
1,444
642 2,957
Plant B
TVA cost Adjusted cost, Base case 1
k$ (1965) k$ (1982) k$ (1982)
324 699
81 606
62 107
1,412 1,772
175 497
324 771
250 430
1,698 l,482b
1,216 3,110 3,254
a. Unit size factor is 0.93 for plant A, 0.60 for plant B; inflation factor is 2.93 for plant A, 2.88 for plant B.
b. Excluding fly ash hoppers.
-------
zz-s
OQ
e
ASH DISPOSAL OPERATING AND MAINTENANCE COSTS, $/ton
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Temporary ponding followed by removal of the ash to a landfill has a
capital investment (32 $/kW), similar to that for landfill, but higher annual
revenue requirements (1.91 mills/kWh) than either direct ponding or landfill.
There is no apparent economic advantage in using temporary ponds at new
plants. Reuse of sluicing water, including treatment to prevent scaling, only
slightly increases capital investment and annual revenue requirements.
The costs for disposal of a self-hardening ash are slightly higher in
cost per ton of ash than disposal costs for nonhardening ash. The higher
costs are due to the use of covered trucks with moisturizers and addition of
all moisture for compaction at the landfill site instead of at the storage
silos. The main cost differences are slightly higher truck costs and slightly
higher bottom ash water treatment costs.
In all cases, disposal site costs are the largest cost element in both
capital investment and annual revenue requirements. Pond cost constitutes two-
thirds of the capital investment and landfill costs constitute about one-third
of the capital investment in the respective processes. The capital investment
contribution to annual revenue requirements as capital charges is the largest
factor in total annual revenue requirements.
Trucking distance has little effect on capital investment and increases
annual revenue requirements moderately because of increased operating costs
and labor requirements. Moisture content has an important effect on trucking
costs.
Ash utilization has a significant effect on costs, particularly for pond
disposal processes. Fifty percent utilization reduces capital investment and
annual revenue requirements about one-fourth for pond disposal and one-sixth
for landfill disposal.
Although the design differs considerably between collection of ash for
wet sluicing and for trucking the overall costs for ash collection systems do
not differ greatly. The capital investment for truck transportation
(including storage silos) is about one-third higher than the capital
investment for sluicing. The annual revenue requirements for trucking are
about twice as high as those for sluicing.
Base case 1 direct capital investment excluding ponds, and operating and
maintenance costs excluding electricity, are in general agreement with
selected equivalent TVA costs when the TVA costs are adjusted for unit size
and cost-basis year.
S-23
-------
ECONOMICS OF ASH DISPOSAL AT COAL-FIRED POWER PLANTS
INTRODUCTION
Ash disposal has been practiced at coal-fired power plants since their
beginnings a century ago. The amount of ash for disposal has continued to
grow as ash-producing factors have expanded. Such factors include the
increasing use of steam coal, the increasing reliance on higher-ash coals, and
the increasing frequency and efficiency in ash collection. For 30 years, coal
use by electric utilities has increased at 5% to 6% per year, supported by
capacity increases and, more recently, by a trend from use of natural gas and
oil to use of coal for new power units. On the other hand, the disposal
requirements for this increased ash production have been partially offset by
the increasing quantities of ash utilization in cement production, road
construction, and other uses.
Over the years, conventional ash disposal has been mostly to ponds, less
frequently to landfills, and sometimes to combinations of the two. The land
requirements have increased with ash production. At many locations, the
availability of suitable disposal sites is becoming a problem that is
complicated by the size of site needed, its distance from the power plant, its
soil conditions and topography, the sensitivity of the surroundings, and land
cost. Recently, Federal and State regulations for disposal have added new
dimensions to the requirements for site preparation, management, and closure.
The interaction of these factors has made decisions on ash disposal
practices more complex. As a result, the economics of various ash disposal
methods are becoming an increasingly important factor in decisions related to
disposal methods.
The purpose of this study is to evaluate the economics of ash disposal
practices for large coal-fired utility power plants representative of current
and projected requirements. Disposal methods using ponds, landfills, and
their combination, are chosen as base cases to depict both established
practice in the industry and state-of-the-art practice that may be required at
many new plants. Because of differences in both the amount and handling
characteristics between ash from subbituminous and most bituminous coals, both
types are included. The effects of variations in distance to the disposal
site, in land cost, in type of ash transportation, and ash utilization are
also included. Other solid and liquid power plant wastes are omitted from the
study. Among these exclusions are mill rejects from coal pulverization,
sludge and other products from flue gas desulfurization (FGD), water treatment
sludges and brines, and miscellaneous washing or refuse streams.
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The five base cases evaluated are (1) direct ponding without water reuse,
(2) the same process with reuse of sluicing water, (3) temporary ponding
followed by landfill, (4) landfill, and (5) landfill of a self-hardening (high-
calcium) ash.
The design and economic premises follow the applicable premises used in
related EPA-TVA studies of sludge disposal and FGD. The study is based on new
installations. The cost and operation of various segments of a new system
could be similar to those in a retrofit installation, but retrofit conversion
is highly site specific and it is not included in the scope of this study.
In addition, the estimated costs developed in this study are compared
with actual TVA costs in areas where costs are available and similarities in
the methods permit. All TVA ash is disposed of by sluicing to ponds, hence
the comparisons are limited to pond disposal.
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BACKGROUND
Utility ash disposal practices in the coming years will depend on many
interrelated factors. The total utility coal consumption will determine, in
part, the quantity of ash produced. The geographical source areas will also
in part determine the quantity of ash and, more importantly, the chemical and
physical properties of the ash. These properties are important determinants
in boiler design, which also affects the characteristics of the ash produced.
Finally, patterns of ash utilization and environmental regulations governing
disposal practices will affect ash collection, handling, and disposal
methods. Many of these factors are in a state of change. Projections of coal
use by utilities vary; traditional geographic patterns of coal production and
utility coal use are changing; the effects of recent environmental legislation
are not fully clear; and ash utilization is becoming a subject of increasing
interest and complexity.
UTILITY COAL USE AND COAL CHARACTERISTICS
Numerous projections of coal use for electricity generation have been
made in recent years, most of which have been widely published and more widely
discussed (1). Though at variance in many aspects, these projections
generally predict an increasing role for coal in electricity production, with
consumption increasing to over 700 million tons by 1985. This is supported by
the dominance of coal as the fuel for new fossil-fuel units (2) as well as an
increasing dominance of fossil-fuel units over nuclear units in recent new
construction (3). Continuing growth in utility coal use is projected for the
rest of the century.
The quantity of ash produced by coal consumption rates of these
magnitudes is enormous. In the early 1970fs coal ash production ranked in the
top ten of nonfuel mineral production tonnages, exceeding such materials as
phosphate rock and salt in tonnage produced (4). By 1977 it ranked fourth,
exceeded only by crushed stone, sand and gravel, and cement. In 1985, at the
projected growth rates for these materials (5) and utility coal use, the
tonnage of coal ash produced will be exceeded only by crushed stone and sand
and gravel. The projected 1985 coal consumption by utilities of 700 million
tons could produce over 100 million tons, or over 2 billion cubic feet, of
ash.
The geographic distribution and characteristics of U.S. coals are well
documented (6,7). Historically, bituminous coals from the Appalachian region
and the Central basins supplied almost all U.S. needs. In the 1970fs, the use
of western coal and lignite from the Northern Great Plains and Rocky Mountain
regions and lignite from the Gulf Coast region greatly increased. Continued
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increase in the use of western coal by utilities is seen in Department of
Energy surveys, both by the increasing number of western power plants (8) and
the increasing use of western coals east of the Mississippi River (9). The
effect of these trends on regional coal consumption and ash production is
shown in Figure 1. The Department of Energy analyses, however, note a
downward trend from previous studies in both projected western power-plant
construction and in coal shipments to eastern areas. These projections
antedate the final promulgation of the 1979 revised NSPS (11) which restrict
the use of low-sulfur coal in lieu of coal cleaning or flue gas
desulfurization. More recent projections, however, support the trends toward
greatly increased use of western coals (12).
Although intraregional and even intrabed variations often exceed regional
variations, several generalizations of interregional differences in coal
characteristics can be made. Almost all eastern utility coals, including
those of the Central basins, are agglomerating, or coking, relatively high-
sulfur bituminous coals that produce ash relatively low in calcium and high in
iron, compared with western coals. Most western utility coals are
nonagglomerating, or noncoking, relatively low-sulfur subbituminous coals or
lignite that produce ash relatively low in iron and high in calcium, compared
with eastern coals. Other regional characteristics, such as chloride and
sodium contents also exist. Radian Corp. (13) and Gibbs & Hill, Inc., (14)
among others have summarized data on regional variations. These variations
affect the characteristics of the ash produced not only directly but
indirectly through their influence on boiler design.
UTILITY BOILER DESIGN
Several types and numerous variations of types of utility boilers exist.
These are extensively described in the literature (15,16,17). A limited
number of stoker-fired boilers are used. These are small and are not a major
factor in considerations of ash utilization and disposal. Except for a
limited number of cyclone furnace designs, large, modern coal-fired utility
boilers burn pulverized coal. Buonicore and others (18) cite unpublished data
showing that about 1% of utility coal is burned in stoker boilers, 14% in
cyclone boilers, 72% in dry bottom pulverized coal-fired boilers, and 14% in
wet bottom pulverized coal-fired boilers.
In pulverized coal-fired boilers the coal is ground to a fine powder
(typically 70% to pass 200 mesh, the consistency of talcum powder) and
injected into the furnace through burners as a suspension in a portion of the
combustion air. The remaining combustion air is injected around the burner
periphery and at other locations to control combustion conditions. Numerous
burner and furnace designs exist, depending in large part on the
characteristics of the coal and the ash it produces. Most constructed in the
last 10 years or under construction are horizontally or tangentially fired;
the burners are aligned to inject the coal-air mixture horizontally into the
furnace or from the furnace corners tangential to an imaginary circle at the
center of the furnace. Figure 2 shows a generalized horizontally fired
boiler.
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REGION
Figure 1. Utility coal consumption and ash production by
geographical region for 1977 and 1985.
(Derived from Ref. 10)
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SUPERHEATERS 8
REHEATER SECTION
Coal
Hoppers
ESP
YYY
I.D. FAN
ESP Ash
F.D. FAN
Air Heater Ash
Sluice Water
Bottom Ash
CLINKER
GRINDER
Figure 2. Generalized pulverized coal-fired utility boiler.
The furnace consists of a vertical chamber (sometimes with internal
partitions) lined with water tube walls that constitute the steam generating
area. The pulverized coal injected in the primary air burns in the
confines of the furnace while mixing with the secondary air injected through
the burners and tertiary air injected at other locations in the furnace.
The furnace may be designed so that the ash solidifies while suspended in
the combustion gases before contacting the furnace walls. In this case part
of the ash, usually about 20%, falls to the bottom as solid particles. Such
designs are called dry bottom or dry ash boilers. If this is impractical
because of the melting characteristics of the ash, the bottom of the furnace
is designed to operate above the melting temperature of the ash so that ash
impinging on the furnace surfaces drains to the bottom as slag. These are
called wet bottom or slag tap boilers. In these furnaces about 50% to 65% of
the ash in the coal is removed as slag. In either case the furnace is
designed so that the ash remaining in the flue gas solidifies before leaving
the furnace. Although dry bottom boilers predominate in numbers, the use of
wet bottom designs is common. In a survey of 41 new boilers by Friedlander
(2) 13 plants reported a wet bottom design.
Bottom ash and occasional chunks of slag, if the furnace is designed as a
dry bottom unit, fall through a throat at the bottom into an ash hopper.
Bottom slag, if it is a wet bottom design, drains down the walls through a
throat into an ash hopper. Dry bottom ash hoppers usually have sloped,
ceramic-lined bottoms that are continually washed with water to quench the
ash. Wet bottom furnace ash hoppers are usually similar, water-filled
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hoppers. Both types are equipped with a clinker grinder. Clinker grinders,
with single- or double-toothed rolls, reduce the quenched slag to a maximum
size of about 2 inches, allowing it to be sluiced into the disposal system.
The flue gas, containing the fly ash, passes upward at about 50 to 70
ft/sec and leaves the furnace at about 2000°F. It then passes through
banks of superheater and reheater tubes in which it is cooled to about
1000°F. Finally, it passes through the economizer, which heats the boiler
feedwater, and the air heater, which heats the combustion air. The flue gas
enters the air heater at about 700°F and leaves it at about 300°F, a
temperature dictated by the necessity of keeping the flue gas above the
sulfuric acid saturation temperature.
Slagging (accumulation of solids on the furnace walls) and fouling
(similar accumulations on convection tubes) are unavoidable handicaps of coal-
fired boilers. Soot blowers, situated at strategic locations in the furnace
and convection sections, dislodge this material, some of which falls to the
bottom of the furnace, contributing a slag component to the suspension-
solidified dry bottom furnace ash.
Flow of air into and flue gas through the boiler is provided by forced
draft (FD) fans that blow air into it and induced draft (ID) fans that draw
flue gas from it. Most boilers are designed to operate at slight negative or
positive pressures in the range of 0 to 2 in. 1^0. Many are balanced draft
designs in which the top of the furnace operates at a slight (about -0.1 in.
H20) negative pressure. The quantity of flue gas leaving the boiler is
determined by the quantity of air needed for efficient combustion and the
quantity of air that leaks in or is added as tempering air. The total
quantity of air entering the furnace is usually about one-fifth greater than
the stoichiometric combustion requirements. Air heater leakage can add an
equal volume of dilution air.
Ash characteristics such as softening and fusion temperature, chemical
composition and ratios of chemical constituents, and abrasiveness are
important considerations in boiler design. Insofar as these relate to coal
rank and geographic source, boiler design is related to the coal rank and
source. Boilers designed for lower rank coals generally have more
conservative heat release rates (Btu/ft^ of radiant heated surface) and are
larger in height and plan area. Flue gas velocity may be lower, resulting in
a higher ratio of bottom ash to fly ash. To decrease fouling, the temperature
of the flue gas leaving the furnace may also be lower.
A second modern design, the cyclone furnace, is in more limited use. It
is particularly suited to low-rank, high-ash coal that has a low fusion
temperature and is difficult to grind. Crushed coal (not pulverized) is blown
into horizontal ceramic-lined, water-cooled combustion chambers that occupy
the same positions as the burners of a pulverized coal boiler. Combustion air
is injected to impart an extremely turbulent circular flow pattern so that the
coal burns rapidly at a very high temperature. About four-fifths of the ash-
forming components are trapped on the furnace walls and are tapped as slag.
The fly ash loading is thus low but it is high in the more difficult to remove
submicrometer size range (19). Cyclone furnaces have seen limited application
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in recent years, in part because of the high levels of nitrogen oxides
emissions they produce. However, they continue to be selected for some new
plants, particularly those burning lignite (2).
COAL MINERAL MATTER AND COAL ASH
The mineral content of coal consists of a small fraction of minerals
incorporated into the growing plants, and a larger fraction of detrital and
authigenic material dispersed through the coal during its accretion,
diagenesis, and postdiagenic history. An additional quantity of mineral
matter is incorporated during mining by the inclusion of surrounding rock,
partings, and nodules. Numerous compendiums and summaries of coal mineral
studies exist (20,21, for example). The major minerals normally consist of
clays, calcium and iron carbonates, quartz, iron sulfides, and gypsum, with
clays usually predominating. A number of minor elements (1.0% to 0.1%)
consisting of metal sulfides, oxides, carbonates, and aluminosilicate minerals
also occur. In addition, many trace elements (less than 1000 ppm) occur in
coal. As they are in most organic-rich sedimentary rocks, many of these
elements are abnormally concentrated, often by orders of magnitude, compared
with normal crustal abundances. The occurrence of these elements in coal ash
has been extensively studied and reported (22,23) because of their potential
physiological effects.
Although the mineral matter in coal is widely studied, it is more
commonly characterized by the ash, determined by controlled combustion tests
or analysis of boiler ashes. Ash compositions and physical properties
determined from laboratory tests may not exactly reflect the characteristics
of an ash produced by the same coal in a boiler, nor will the ash produced in
a particular boiler necessarily characterize ashes from the same coal in other
boilers.
In a pulverized-coal-fired boiler the coal particles are about 100
micrometers in size. At this size the bulk homogeneity of the coal is lost
and the particles range in composition from essentially pure coal to pure
mineral matter. In the furnace the coal is pyrolyzed, forming char as the
volatilized matter burns. The char may, depending on the coal, pass through a
liquid stage, as it in turn is burned. This combustion process occurs in less
than a second at temperatures of about 3000°F while the particles are
suspended by the turbulence of the injected combustion air and burning gases.
Some mineral matter in the coal particles forms molten particles. Other
particles composed mainly or wholly of mineral matter are melted or softened.
These particles continue to react, combine, and disintegrate until they
solidify in the flue gas or impinge upon and stick to the furnace walls. Some
ash components such as carbonates and sulfides, are decomposed and form
gaseous oxides. Components such as the alkali metals and numerous trace
elements are partially or wholly vaporized and condense as submicrometer
particles or as surface coatings on existing particles as the gas cools,
creating a fractionation of elements between the fly ash and bottom ash. The
final physical and chemical characteristics of the ash depend on the original
coal composition, the degree of pulverization, and the time-temperature-
turbulence history of the particles. The final composition is a mixture of
vitreous and crystalline oxides and silicates in which silicon, aluminum,
iron, and sometimes magnesium and calcium are major components.
8
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FLY ASH
Fly ash is composed of well-graded.particles ranging in size from a small
fraction of a micrometer to over 100 micrometers, a range encompassing the
sizes of clay through fine sand. The geometric mean diameter is usually in
the range of 10 to 20 micrometers, with 1% to 10% below 1 micrometer and about
90% below 100 micrometers (19). Southern Research Institute (24) reports
similar data for pulverized coal ashes and describes measurement techniques.
The morphology of fly ash particles has been widely described. Published
scanning electron microscopy photomicrographs (25,26, for example) have made
its appearance familiar. Most fly ash particles consist of vitreous, often
translucent, spheres that are frequently hollow to some degree and may contain
smaller spheres (27). Others consist of irregularly shaped particles,
fragments of spheres, sintered agglomerates, and porous carbonaceous
fragments. The term cenosphere has been variously applied to the hollow
spheres as a generic term (26) and as a term for the fraction that floats in
water. The major constituents, reported as oxides, are silicon, aluminum, and
iron. Calcium, magnesium, and sodium seldom exceed 2% each in most ashes from
eastern bituminous coals. In ashes from western coals and lignites, however,
the calcium content usually exceeds that of iron and is usually in the 10% to
20% range. Magnesium and sodium contents are also usually higher in western
coals. Carbon contents are highly variable, often less than 1% but ranging up
to 20% (22) or higher (28). Carbon content is, of course, a function of
perhaps transient combustion conditions rather than intrinsic properties.
A host of other elements occur in fly ash. These have been extensively
studied (20,22,23, and 29 all provide extensive compilations). Many of the 25
to 40 elements abnormally concentrated in coal occur in the ash at levels
sufficient to cause apprehensions as to the environmental effects of its
disposal or use. Among these are radionuclides (30,31) and numerous
physiologically active elements. Most of these elements, particularly
antimony, selenium, arsenic, and lead are enriched in the fly ash fraction of
the ash.
There is also a considerable variation of chemical composition with
particle size, and in some cases between the surface and interior portions of
the particles. This is true of both major and minor elements as a result of
the original inhomogeneity of the coal particles and the thermal fractionation
that occurs during combustion and subsequent cooling. Coles and others (32)
in addition to the authors cited above provide a discussion with extensive
references of these phenomena.
Although the compositions of coal ashes are almost always reported as the
oxides or as elemental components, X-ray crystallographic and petrologic
studies have reported a number of oxide, silicate, sulfate, and other minerals
in fly ash. This mineral composition and its variation along with chemical
composition and fractionation, is undoubtedly an important factor in the
chemical and physical behavior of the ash.
In appearance fly ash is a gritty powder ranging from black through
various earthy colors to light tan. In many engineering properties fly ash is
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often compared to a light silty soil. It differs in several, some
advantageous, aspects, however. Chae and Snyder (33), Srinivasan and others
(34), and Seals and others (35) have described specific engineering studies.
GAI Consultants, Inc., (36) have summarized fly ash engineering properties,
along with an extensive discussion of their measurement and application.
Fly ash grain size is well graded and generally falls in the size
distribution range between silty clay and silty sand. Specific gravities of
less than 2.0 to 3.0 have been reported (37) but those in the range of 2.1 to
2.6 are commonly reported, considerably lower than soils of similar particle
size, which are in the 2.5 to 2.8 range. Aerated dry bulk densities of 35 to
65 Ib/ft^ (38) and compacted dry bulk densities of 75 to over 100 Ib/ft^
(33) have been reported. The dry bulk density of fly ash settled in ponds may
be considerably less, however (39). Dry fly ash lacks cohesion although it
develops a considerable apparent cohesion at certain moisture levels because
of capillary attraction, a property of dubious value in engineering
considerations of shear strength. Values for the angle of internal friction
between 25° and 40° are cited by GAI Consultants (36), a range that spans
those of common soils from clay (19°-28°) to gravels (about 38°).
Generalizations of shear strength are complicated by cementitous reactions
that may occur with time, particularly with high calcium fly ashes. Fly ash
is also generally described as having no plasticity, a common soil property,
as measured by Atterburg limits tests. The compressibility of fly ash, the
tendency to decrease in volume under load, is similar to the compressibility
of a cohesive soil such as silt. Permeabilities vary considerably. GAI
Consultants (36) report a range of 10"? to 10~^ cm/sec for compacted fly
ashes, a range encompassing clay through porous silt. The degree of
compaction has been shown to have an important effect on permeability (34), as
have cementitious reactions.
Very little has been published on the dewatering characteristics of fly
ash. GAI (36) cites a study in which capillary rise in fly ash could range
from 6 to 32 feet. DiGioia and others (40) cite a study of an unidentified
temporary ash pond with an impervious liner in which the capillary rise in fly
ash was 7 feet. The ash had to be stacked and drained beside the pond before
it could be trucked. The capillary zone was eliminated by an underdrain.
FLY ASH COLLECTION
Some fly ash settles out in low-velocity areas of the boiler such as the
economizer and air heater. Economizer ash shares some characteristics with
bottom ash. It is coarse compared with fly ash and sometimes contains
appreciable unburned carbon. Economizer ash also has a tendency to sinter if
it remains in contact with the hot flue gas. It is sometimes collected in
water hoppers and sometimes in dry hoppers thermally isolated from the flue
gas by a throat or chute. Its disposal may be either a part of the bottom ash
sluicing system or the fly ash pneumatic system.
Fly ash can be removed from flue gas with mechanical collectors, wet
scrubbers, electrostatic precipitators (ESP's), or fabric filters. To meet
the current emission regulations very high removal efficiencies, usually above
99% and sometimes higher than 99.9%, are required. Mechanical collectors (41)
10
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cannot meet these requirements. They are used when partial cleaning is
desirable in conjunction with other control devices. Wet scrubbers are in use
at several utility power plants (42) and are planned for others (2). The
primary disadvantages of scrubbers are the high energy requirements because of
the large flue gas pressure drops necessary for high removal efficiencies and
the large volumes of liquid that must be circulated. Wet scrubbers, many of
novel design, continue to be an important factor in utility fly ash control,
however (43).
ESP's have been widely used in industrial applications for many years and
are well described in emission control literature (19,48). Particles are
collected in an ESP by charging them by exposure to ions and passing them
through an electrical field between two electrodes so that they migrate to and
collect on one of the electrodes. In the most common electrical utility ESP,
the ions are created by a corona discharge from a negatively charged wire or
wirelike electrode between two platelike passive collection electrodes. As
the flue gas passes through arrays of these electrodes the fly ash particles
become charged and adhere to the collection electrode. Periodically the fly
ash layer is removed, usually by rapping the electrode, and collected in
inverted-pyramidal hoppers beneath the electrodes.
Removal efficiencies well in excess of 99% can be practically attained
under many conditions. The specific collection area (SCA), expressed as
collection electrode area per unit volume of flue gas (ft2/1000 ft3) is
largely determined by the fly ash resistivity. Uncommonly, a low resistivity
can result in rapid particle charge decay and reentrainment. More
characteristic of coal fly ash, high resistivity results in a low corona
current flow and reduced collection efficiency and eventually in electrical
breakdown of gases in the particle layer. In addition to fly ash composition,
fly ash resistivity is determined by flue gas temperature and the presence of
materials such as 803 and sodium in the flue gas. The most desirable ESP
location is usually downstream from the air heater where the operating
temperature and flue gas volume are lower, ducting is simplified, and heat
losses minimized. These cold-side ESP's operate at about 300°F, near the
temperature of maximum resistivity for fly ash. For collection of high-
resistivity fly ashes a hot-side ESP situated between the economizer and air
heater is sometimes more practical. Resistivity is also reduced by the
presence of gaseous conditioners such as 803 for cold-side ESP's and sodium
for hot-side ESP's, either present in the coal or introduced as an additive.
Numerous other additives have been evaluated (49).
In general, high-sulfur Eastern U.S. coals produce ash more amenable to
collection in ESP's and low-sulfur Western U.S. coals produce ash less easily
collected. Cold-side ESP efficiencies in excess of 99% can often be attained
at SCA's of 100 to 300 ft2/1000 ft3 with fly ash from Eastern U.S. coal,
while SCA's for Western U.S. coals under similar conditions would be over 500
ft2/1000 ft3.
Fabric filters are a more recent adaptation to utility flue gas emission
control, their development for this use paralleling the development of durable
cloths that are practical at the temperatures involved. Bechtel (44) has
discussed the early applications of fabric filters in utility fly ash
collection. Utility interest has been summarized by Reigel and Bundy (45) and
11
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more recently by EPA symposium compilations (46). A typical fabric filter
baghouse installation consists of arrays of fabric tubes, often about 1 foot
in diameter and 30 to 40 feet long, attached at their open ends to a dividing
tube sheet partition in the baghouse enclosure. Flue gas enters through the
bottom open end of the commonly used low-ratio designs, with inside to outside
flow, and passes through the bags into the bag compartment. Periodically the
fly ash layer is dislodged by a reversed flow or a reversed pulsed flow of
air, or by mechanical shaking, or both, and falls into a collection hopper.
Interest in fabric filters has been increased in recent years by several
factors. Very high collection efficiencies needed to meet stringent emission
regulations are sometimes achieved more easily and economically by fabric
filtration. Fabric filters are insensitive to fly ash characteristics such as
resistivity that affect the efficiency of ESP's. In addition, fabric filters
are efficient collectors of the 0.1 to 1.0 micrometer particles that are
physiologically important (47) and also cause opacity problems.
BOTTOM ASH
Compilations of data on bottom ash are less extensive than those on fly
ash. Rose (28), Ray and Parker (29), and Moulton (50) have published physical
and chemical data. Srinivasan and others (34), Digioia and others (40), and
Magidzadeh and others (51) have discussed engineering properties. Bottom ash
from dry bottom furnaces consists of dark, highly vesiculated, vitreous,
angular to spherical fragments with a size distribution of about 0.1 to 40
mm. Texturally, the particles range from dense pieces of slag to porous,
sintered agglomerates. Bottom ash has a major element composition similar to
fly ash, mostly aluminum and iron silicates and oxides, but it is depleted in
volatile elements relative to the original coal mineral composition. It is
also usually less reactive than fly ash because of the larger, more vitreous
nature of the particles (20). Loss on ignition (representing for the most
part unburned carbonaceous material and sulfur) from less than 1% to 33% have
been reported for bottom ash from pulverized-coal-fired boilers using eastern
coal (28), considerably higher than that of fly ash from the same units.
Bottom ash is reasonably well graded, with particle sizes ranging from
fine sand to coarse gravel. Most particle sizes fall in the range of fine
gravel to medium-fine sand (10 to 0.2 mm, or 3/8 to 1/16 inch). Specific
gravities of 2.3 to 2.8 have been reported for bituminous coal bottom ash from
dry bottom furnaces (50); the higher specific gravities were attributed to
high iron contents. Others (51) report bottom ash specific gravities of 2.1
to 2.5. In comparison, silica sand has a density of about 2.6. Compacted
bulk densities of 50 lb/ft-* to over 100 Ib/ft^ have been reported.
Angles of internal friction on the range of 30° to 40° have been
reported, values similar to those of sand and gravel. Uniaxial compression
tests also show a behavior similar to sand. The permeability of bottom ash is
in the range of 10"* to 10~2 cm/sec, again in the range of sand. The
permeability is relatively unaffected by compaction, compared with fly ash
(34).
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ASH HANDLING
Ash handling and disposal consists of removal of the ash from the bottom
ash hoppers, the economizer, air heater, and other auxiliary hoppers, and from
the ESP fly ash hoppers; transport of the ash through various intermediate
collection and storage facilities to final disposal, or directly to final
disposal; and management of the disposal sites. A variety of methods may be
used to accomplish these tasks (38). These combine with individual design
variations (53) to produce what is essentially a unique system, adapted to
each power station's fuel and boiler characteristic and disposal
requirements. Within this diversity, however, distinctive general patterns
exist, particularly for large, new central stations, that characterize utility
ash disposal methods.
Flv Ash
Inverted pyramidal hoppers that form the bottom of the collection device
are usually used to collect the fly ash. Fly ash is usually hygroscopic to
some degree and the flue gas atmosphere usually has a sulfuric acid dewpoint
of about 250°F and a water dewpoint of about 150°F. Packing, caking, and
cementitious reactions can be a major problem if the ash is allowed to cool
below these dewpoints (54). The hoppers are often insulated and heat traced
to prevent this.
Fly ash is normally removed from the hoppers on an intermittent basis
using a pneumatic conveying system. Vacuum systems using a hydraulic ejector
in which the ash-air mixture is drawn directly into the ejector are common.
The resulting ash slurry, composed of 5% to 10% solids, can be pumped or can
flow by gravity directly to dewatering or final disposal ponds. Vacuum
systems using vacuum pumps in which the ash is collected in mechanical
separators and fabric filters are also used. Vacuum systems are limited to a
few hundred feet of length and their efficiency is reduced at high altitudes.
Pressure systems may be used, alone or in conjunction with vacuum systems, for
higher capacities or longer distances. Ash-to-air weight ratios vary,
depending on the system from over 30 to 1 to about 6 to 1 . Velocities vary
from about 300 ft/min to a few thousand ft/min.
Fly ash collected by direct ingestion in hydraulic ejectors is usually
sluiced to ponds of several years' capacity rather than short-term dewatering
ponds. Fly ash collected in silos may also be reslurried and pumped to a pond
although it is more frequently moistened for dust control and hauled to a
disposal site. The silos are often elevated for direct loading through a
moisturizer into rail cars or trucks.
Bottom Ash
Bottom ash hoppers usually have a capacity of several hours. The ash
level is monitored with instruments or visually and the hoppers are emptied
either as necessary or on a working-shift time basis. In most cases a
hydraulic sluicing system is used. The ash door to the clinker grinder is
opened and the ash is flushed through the clinker grinder and into the
transportation pump with high pressure water jets mounted inside the hopper.
13
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Either water ejector pumps or centrifugal pumps are used. Ejector pumps are
simpler to service though less efficient and limited in pumping head. If a
centrifugal pump is used water is added at the suction to dilute the slurry
and at the bearings to prevent erosion. Slurry concentrations of 1% to 5% are
most common. Velocities in the range of 10 ft/sec are necessary to keep the
ash in suspension. Remixers or agitators every few thousand feet may also be
necessary.
The subsequent handling of the bottom ash is largely a matter of site-
specific circumstances. The ash may be pumped to a disposal pond» to a
dewatering pond, or to dewatering tanks. The disposal system may also be
combined with other disposal systems. Mill rejects (also called pyrites), the
noncoal mineral waste collected from the pulverizers, and economizer ash are
frequently transported in the bottom ash system. Hydraulically collected fly
ash may also be transported in the same lines.
Along with pumps and ejectors, transport lines suffer from high wear
rates because of the abrasive bottom ash. Hard steel pipe and fittings,
basalt and ceramic liners, and replacable wear plates are frequently used to
reduce wear. Pipes are also rotated to equalize wear.
Commercial equipment specifically designed for utility ash handling is
available from a number of suppliers (53), some of whom offer European
designs little used in the United States. In particular a low-headroom bottom
ash system called the submerged scraper conveyor or submerged drag bar chain
conveyor (55) and dense-phase pneumatic systems (56) have received attention.
The former is common in Europe. The bottom ash falls from the furnace into a
shallow flat-bottom hopper filled with water. It is continually removed by a
drag conveyor which operates horizontally and submerged in the hopper, then
upward along an inclined dewatering trough. Depending on subsequent needs,
the ash may be crushed and trucked or sluiced from the surge hopper to
disposal.
Ash Disposal
Several general or specific surveys of ash disposal methods have been
made. One of the most comprehensive is that by Versar, Inc., for EPA (57) in
which over 200 power-plant ash disposal practices were surveyed. Radian
Corporation (58) conducted a similar survey. More commonly, specific sites or
aspects of specific sites are reported (59).
Transportation of ash to disposal or storage sites is decidedly a site-
specific operation. Sluicing to diked ponds for either final disposal or
temporary storage is common, as is trucking to captive or commercial
landfills. Not uncommonly, particularly with bottom ash, the ash is removed
from settling ponds and landfilled or utilized. Trucking by a variety of on-
road and off-road designs is the most common method of dry ash
transportation. Both captive and contract trucking operations are employed.
On the average, the distance to the disposal site is short, averaging about
three miles with over nine-tenths under five miles (60). Exceptions exist,
however, particularly when trucking is used because land is not available in
the vicinity of the power plant.
14
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Ponding of sluiced ash is a common practice used in one form or another
by more than half of the U.S. utilities (58), most commonly by those east of
the Mississippi River (57). In most cases the fly ash and bottom ash are
sluiced directly to separate or combined final disposal ponds. In some cases
the ash is removed and landfilled, either as a planned procedure or as an
expedient to extend the pond life. Temporary ponding is used more frequently
for bottom ash than for fly ash. A substantial percentage of utilities use
dry handling and landfill for fly ash and temporary or permanent bottom ash
ponding. In lieu of temporary ponds mechanical dewatering systems may be used
for bottom ash.
Ponds differ greatly in design and capacity. Usually earthen dikes are
used, frequently incorporating natural topography or manmade excavations such
as quarries to form a part of the impoundment. Pond lives range from a few
years to well over 30 years. Pond depths are generally in the range of a few
dozen feet. Some, incorporating topography in hilly terrain may have depths
of over 100 feet, however. Most ponds now in use are not lined in the sense
that synthetic or imported earthen materials were emplaced.
Landfills share with ponds a heterogeneity of type and size, use of
manmade and natural features, and other characteristics of morphology and
development. Landfills range from structured constructions to back dumping in
convenient depressions or excavations. As with ponds, topography often serves
to define the form and structure of landfills. Unlike ponds, however,
landfills show no strong climatically related distribution. The choice of
landfill disposal may be the result of lack of nearby land or lack of
sufficient water for sluicing. Not uncommonly, power plants supplied by
nearby surface mines dispose of ash in the mined-out area.
Further complicating the characterization of ash disposal practices are
variations in ash utilization practices. In a few cases ash is routinely sold
or given away to commercial operations. In others, however, ash is
intermittently sold or given away as temporary outlets occur. Sometimes
appreciable quantities are thus disposed of in a short time, altering the
normal power-plant disposal practices (60).
Ash disposal practices, as represented by operating power plants in the
late 1970's, are dictated by many factors. Among these are availability of
water, availability of land, local and state regulations, topography, geology,
utility experience, and availability of utilization outlets. All of these in
their many combinations act to produce highly individualistic disposal
practices. In some cases different methods may be employed at the same site,
in others practices may change with time. Ponding of hydraulically
transported ash, ponding followed by excavation and landfill, and direct
landfill of dry ash, all in numerous variations, are the primary methods of
current ash disposal practices. In addition, a minor to major portion of a
particular power plant's ash may be routinely or intermittently sold or given
away for utilization.
Several factors will tend to alter future disposal practices. Paramount
among these are environmental regulations affecting ash disposal
primarily through restrictions on pollution of surface and ground water.
Other factors may also be influential, among them a diminishing availability
15
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of land, increasing construction of power plants in dry climatic zones, and
increasing sophistication of ash utilization. Among the practices likely to
be influenced are methods that discharge suspended and dissolved material to
surface and ground waters, methods that cause cementitious reactions that
hinder disposal operations, and methods that reduce the usefulness and
therefore the utilization of the ash.
WASTE DISPOSAL REGULATIONS
Disposal of power plant ash, along with other power plant wastes, may be
subject to numerous Federal, State, and local regulations. These are
administered by several agencies, and pertain to various aspects of industrial
health and safety in addition to environmental considerations. Santhanam and
others (61) discuss the regulatory structure of power plant waste and water
management. Rice and Strauss (62) discuss power plant water pollution
control.
The disposal of power plant ash in ponds and landfills is primarily
affected at the Federal level by the Clean Water Act (CWA) and the Resource
Conservation and Recovery Act (RCRA) of 1976. Other disposal methods such as
well injection and mine disposal are affected by other Federal regulations as
well. Since one of the primary intents of these laws is the encouragement of
State programs, much of the legislation directly affecting ash disposal is in
the form of minimum standards and guidelines. It thus represents standards
that may be superseded by more extensive or stricter regulations in particular
applications (63).
The CWA requires establishment of procedures and regulations to control
discharge of pollutants into navigable waters. Under it, the National
Pollution Discharge Elimination System (NPDES) was established. This requires
a permit for each point source discharge into navigable waters. The permit
establishes specific pollutant concentrations and monitoring requirements for
the source that it applies to. Although emphasis, particularly in the 1977
amendments, has been placed on toxic pollutants, initial guidelines were for
so-called conventional pollutants such as suspended solids, oil and grease,
and sewage-derived materials, and for extreme pH's. When EPA promulgated
effluent guidelines and standards for power plants (64,65), criteria for total
suspended solids (TSS), oil and grease, and pH were established for ash
transportation water and ash disposal site runoff. These require best
available technology economically achievable (BAT) for existing sources to be
attained by 1984 and using new source performance standards (NSPS).
16
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Average mg/1
BAT NSPS
Bottom ash transportation water
TSS 30 30
Oil and grease 15 15
Fly ash transportation water
TSS 30 None
Oil and grease 15 None
Runoff
TSS 50 50
pH, all discharges 6-9 6-9
More recently EPA established proposed effluent standards (66) for some
toxic pollutants, including a number of ash trace elements, that are to be
incorporated into NPDES permits.
RCRA has been generally described in journals (67). The law amended
existing Federal solid waste laws with the stated objective of protecting
public health and the environment and encouraging conservation of national
resources, primarily through the encouragement and support of State regulatory
programs and conservation measures. Attention primarily focused on Subsection
C of the law, which establishes a regulatory program for hazardous wastes, and
Subtitle D, which provides for Federal assistance to States in the management
of nonhazardous wastes. Subtitle C in particular provides for strict and
extensive minimum standards on the handling and disposal of materials
designated as hazardous by criteria established by EPA.
In 1978 and 1979 (68,69) EPA published proposed rules for control of
hazardous wastes under Subtitle C. In these, utility wastes, including ash
and FGD waste were, among others, classified as special wastes subject to
Subtitle C regulations at least in part. The stated purpose of this
classification was to permit time for further study of the nature of these
wastes, for which limited information existed. In placing these wastes in
this special category, EPA indicated that they were not certain what
percentage was, in fact, hazardous. Inclusion of utility wastes in this
category created some misinformation and considerable distress among those
concerned with these wastes (70). Utilities already struggling with
relatively new technologies to cope with environmental regulations were
concerned with the prospect of much more rigid and expensive control. To
others, the prospect of a hazardous waste stigma becoming attached to
materials that they were attempting, with some success, to promote as useful
raw materials was equally disturbing (71).
Some studies were already in progress to characterize the behavior of
utility ash wastes and waste monitoring requirements. Radian Corporation (72)
reported on studies of trace element behavior in ash pond leachates. Theis
(73) made a field study of ash pond leachate. EPA and TVA began studies to
characterize coal-fired utility plant effluents in the late 1960's, such as
ash pond effluent monitoring reported by Miller and others (74) and the ash
studies of Ray and Parker (29). Other studies were initiated or shaped, at
least in part, by RCRA. EPA initiated a program to develop information on
17
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utility ash disposal, including the survey of existing practices by Versar,
Inc., (57), who gathered information from about two-thirds of U.S. utility
power plants. Engineering-Science (10) conducted a study on ash disposal
costs of representative U.S. utilities as part of a continuing study by the
Department of Energy. This study evaluated disposal methods and costs for
application of RCRA hazardous and nonhazardous alternatives. The hazardous
waste regulations used in this study were based on the original regulations
proposed in 1978 (68). EPRI has sponsored studies to review the relationship
of utility waste characteristics to RCRA requirements such as that by Fred C.
Hart Associates, Inc., (22) and to summarize existing data on utility solid
wastes (23). The EPRI Fly Ash Structural Fill Handbook (36) and Ash Disposal
Reference Manual (75) also pertain directly to current ash disposal
requirements.
Early in 1980 EPA began promulgating final regulations on much of the
RCRA Subsection C hazardous waste regulations (76,77). Among these (77,
p. 33120) were exclusions for "fly ash waste, bottom ash waste, slag waste,
and flue gas emission control waste generated primarily from the combustion of
coal or other fossil fuels." The rationale for this exclusion (77, pp. 33173-
33175) was relaxation of the definition of properties that would bring these
materials into Subtitle C, increased flexibility in Subtitle C waste
management requirements, and anticipation of Congressional action which would
defer the regulations for utility wastes, among others. Later in 1980 an EPA
study was established by congressional mandate to study coal combustion
wastes. This study is being conducted by Arthur D. Little, Inc. In the
meantime, these wastes are excluded from both Subtitles C and D of RCRA.
Subtitle D of RCRA, State and Regional Solid Waste Plans, is directed to
the control of nonhazardous waste disposal methods through the establishment
of minimum criteria and the encouragement of State and regional management
plans. EPA promulgated these criteria in 1979 (78). The criteria establish
minimum standards for classification of a disposal facility as a sanitary
landfill. Those facilities not meeting the criteria are by definition open
dumps, which are prohibited by RCRA. There are numerous exclusions for
activities and substances controlled by other regulations, including point
source discharges subject to NPDES permits. The criteria are general in
nature and focus on protection of sensitive areas, groundwater, surface water,
and air qualities. Details of preferred methods of operation are not
specified. Among the criteria most pertinent to utility ash disposal are
floodplain, wetland and endangered species habitat, siting restrictions, and
limitations on groundwater and surface water contamination.
The manner in which Subtitle D criteria will affect utility ash disposal
practices has not been fully assessed. The effects are likely to be varied,
particularly since State regulations vary and other Federal environmental
legislation will also affect changes in existing practices. Engineering-
Science found that most States report that the majority of existing sites meet
Subtitle D requirements, a view contrary to the survey of Engineering-Science
(10). Provisions of the Clean Water Act such as NPDES will also alter current
water use practices such as once-through use of water in sluicing. The
general field of water reuse is widely discussed (79). Chu and others (80)
and Noblett and Christman (81), among others, discuss water reuse in utility
waste applications.
18
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LEACHATE
Both field and laboratory studies of ash jleachate have been made. These
have been summarized by Fred C. Hart Associates (22), Radian (23), and GAI
Consultants (36), among others. Theis and oth;ers (73) studied trace elements
in ground water around an ash pond. Miller and others (74) conducted a study
of ash pond effluents. Radian (72) conducted laboratory studies of trace
elements in fly ash and bottom ash leachates, including attenuation by seepage
through clay soils. Ash leachates are generally alkaline although some are
acidic. Some ash pond effluents require pH adjustment to meet the NPDES
maximum of 9.0 (57). The water-soluble fraction of bituminous fly ash ranges
from minor to several percent. Typically calcium and sulfate are the major
dissolved species, along with aluminum, iron,! silica, magnesium, sodium, and
potassium in the range of several ppm and somjetimes chloride in the range of
100 ppm. Most of the trace elements found in the ash are usually identified
at low levels. The level and composition of dissolved solids depend on many
factors other than ash composition, including the pH, leachate volume,
equilibrium relationships, and attenuation by jsoil and dissolved species from
the ash such as iron and magnesium. Radplan (72) found a considerable
attenuation by clay-containing soils. Theisj and others (73) found similar
attenuations in field studies, as well as concentration excursions related to
operational variations such as pond filling j rates. Generalization of ash
leachate characteristics in disposal sites is further complicated by the
previous handling history, such as sluijcing and temporary ponding,
cementitious reactions, inclusion of other power plant wastes, and seepage
rates.
ASH UTILIZATION
Coal ash, along with other types of similar ashes and slags, has long
found widespread if limited use, primarily asj structural fills and bases and
as an aggregate in concrete and bituminous surfaces. These continue to be the
primary uses.
Table 1 shows utility ash production and use patterns for 1977. About
one-fifth of the ash produced was utilized, mostly for concrete aggregate and
road construction, either directly or after disposal. Fly ash represents the
largest quantity used but the smallest percentage in terms of quantity
produced. Boiler slag, mostly the shattered! slag from wet bottom furnaces,
has the highest utilization rate. It is cotuposed of large dense particles
that can be conveniently crushed to make sized aggregate and grit for coatings
and other uses.
In recent years the use of ash has been extensively studied, promoted,
and broadened. The proceedings of the ash utilization symposiums sponsored by
the National Ash Association (82,83,84) illustrate the scope of these
efforts. Much effort in ash utilization continues to be directed toward
conventional uses. Many studies consist of
evaluations of ash in concrete.
concrete products, and in structural fills. In addition, there is an
increasing effort to establish criteria and standards for ash properties to
legitimate its credentials as a construction material. Increasingly, however,
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TABLE 1. ASH COLLECTION, UTILIZATION, AND DISPOSAL, 1977
Fly; ash Bottom ash Boiler slag
106 106 106
tons % tons % tons %
Collection
Ash collected 48.5 71.5 14.1 20.8 5.2 7.7
Utilization
Direct usage
Cement 2.3 37 0.1 2 0.1 3
Road construction 1.7 27 1.3 28 0.3 10
Ice control - - 1.0 22 0.4 13
Roofing - - - - 1.5 48
Miscellaneous 0.2 3 0.4 9 0.7 22
Removed from site at
no cost to utility 0.4 7 0.8 17 0.1 4
Utilized from site
after disposal cost
was incurred 1.6 26 1.0 22
Total 6.3 100 4.6 100 3.1 100
Percent
utilization 13.0% 32.6% 60.0%
Disposal
Permanent disposal 42.2 78.4 9.5 17.7 2.1 3.9
Disposal for
utilization 1.6 61.5 1.0 38.5 0 0
Total 43.8 77.7 10.5 18.6 2.1 3.7
Disposal for utili-
zation as % of
ash collected 3.4% 7.1% 0.0%
Disposal as % of ash
collected 90.3% 74.5% 40.4%
Totala
106
tons %
67.8 100.0
2.5 18
3.3 24
1.4 10
1.5 11
1.3 9
1.3 9
2.6 19
14.0 100
20.7%
53.8 100.0
2.6 100.0
56.4 100.0
3.8% <
83.2%
a. Adapted from data by the National Ash Association.
20
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more specific and exotic uses have been advanced. Use of cenosphere fractions
as fillers, the use of the magnetic fraction for heavy medium separations, and
recovery of metals such as aluminum or trace elements have been advanced. The
use of fly ash in flue gas desulfurization processes either as an absorbent or
absorbent amendment (85) or more frequently as a waste stabilization additive
(86) is also growing.
The quantity of ash utilized has consistently grown for many years as a
result of these and other applications. At the same time, however, the
quantity of ash produced has grown. Consequently, as the percentage of ash
utilized has increased so has the quantity disposed of, as shown in Figure 3.
Both utilization and disposal are likely to remain important for many years.
The growing emphasis and increasing specialization of ash utilization may,
however, have important effects on ash collection, handling, and disposal.
Specialized uses requiring particular physical or chemical properties, such as
particle size or chemical reactivity, could dictate specific collection,
handling, and storage methods. It has been suggested, for example, that
utilities consider utilization requirements as a factor in boiler design (4).
21
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1,000
100
10
Coal consumption
1966-1978
5.3%/yr increase
Ash collection
7.6%/yr increase
Ash disposal
6.4%/yr increase
Ash utilization
13.6%/yr increase
1950 1955 1960 1965 1970 1975 1980 1985
YEAR
Figure 3. Utility coal consumption, ash production, and ash utilization
1950-1978. (data from Faber, J. H., Ref. 71)
22
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PREMISES
The design and economic conditions used in this study to evaluate the
economics of ash disposal are based on premises developed by TVA in 1979 for
evaluations of this nature. The premises are designed to represent current
industry conditions and to provide equitable cost comparisons in significant
and useful divisions. TVA has used similar premises for EPA-sponsored
economic studies made for the past dozen years. The premises used in this
study are revisions of premises used during the late 1970's, updated to
reflect design, economic, and regulatory conditions of the 1980's.
DESIGN PREMISES
The utility plant design is based on Department of Energy (DOE)
historical data (87), general industry information, and TVA experience. The
conditions are representative of a typical modern pulverized-coal-fired boiler
for which current emission control practices would be most likely applied. A
midwestern location is used because of the concentration of power plants and
the diversity of coals used for fuel in this area.
Environmental Standards
The NSPS established by EPA in 1979 for particulate matter, SC>2, and
NOX emissions, specify a maximum emission, based on heat input, of 0.03
Ib/MBtu for particulate matter. This removal efficiency is used for this
study. ESP's with removal efficiences above 99% are assumed to be the
collection method. To facilitate cost comparisons the same SCA is used for
both coals. It is also assumed that other emission requirements are met by
methods independent of, and having no economic effect on, ash collection and
disposal.
Except for base cases 1 and 3 disposal sites are assumed to be governed
by the NPDES, NSPS, and RCRA Subtitle D guidelines. Base cases 1 and 3 are
assumed to be governed by NPDES BAT requirements. It is assumed that no
treatment or specific controls for excessive levels of nonconventional
pollutants other than a liner is required. (A liner is not a regulatory
requirement.)
The coal characteristics are composites of published data on utility coal
compositions. They represent types of utility coals expected to be in general
use in the early 1980's (9,88,89). The eastern coal composition is an average
of coals from the Appalachian region and the Illinois basin. The western coal
23
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composition is a similar average of western coals, not all of which are
subbituminous, from various coal fields that supply utilities in the West and
Midwest. The coal compositions are shown in Table 2.
TABLE 2. COAL COMPOSITIONS
Component
C
H
0
N
S
Cl
Ash
Moisture
Wt % as
High-sulfur
eastern
66.7
3.8
5.6
1.3
3.36
0.1
15.1 (2% Ca)
4.0
fired
Low-sulfur
western
57.0
3.9
11.5
1.2
0.59
0.1
9.7 (10% Ca)
16.0
Ash compositions are based on averages of ash compositions typical of the
coals used. With the exception of calcium content the compositions are not
qualified in terms of physical and chemical behavior. Both ashes are assumed
identical in handling properties until wetted. The eastern coal ash is
assumed to have no cementitious self-hardening properties affecting handling
and disposal site emplacement. The western coal ash is assumed to have self-
hardening characteristics that affect handling and emplacement within a few
hours after being wetted.
Flue Gas Composition
Combustion and emission conditions used to determine flue gas composition
are based on boiler design and the coal compositions listed in Table 2. Flue
gas compositions are based on combustion of pulverized coal using a total air
rate equivalent to 139% of the stoichiometric requirement. This includes 20%
excess air to the boiler and 19% air inleakage in the boiler air heater, which
reflect operating experience with horizontal, frontal-fired, coal-burning
units. It is assumed that 80% of the ash present in the coal is emitted as
fly ash and 85% and 92% of the sulfur in the coal is emitted as SOX for the
western and eastern coals respectively. The base case flue gas composition
and flow rates calculated for these conditions are shown in Table 3.
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TABLE 3. BASE CASE FLUE GAS COMPOSITIONS AND FLOW RATES
Flue gas
component
N2
02
C02
S02
S03
NOX
HC1
H20
Ash
Eastern
Volume ,
75.21
5.54
12.34
0.20
0.01
0.03
0.01
6.66
- '
coal, 3.5% S
% Lb/hr
3,851,000
323,900
992,300
24,330
940
, 1,908
\ 418
219,100
49,040
Western
Volume,
73.09
5.39
12.24
0.04
-
0.03
0.01
9.20
-
coal, 0.7% S
% Lb/hr
3,887,000
327,200
1,023,000
4,760
184
1,590
504
314,600
38,000,
Total 100.00 5,463,000 100.00 5,597,000
Power Plant
A single horizontally fired, dry-bottom, balanced-draft boiler with a 500-
MW adjusted gross electrical output is used. The adjusted gross output is not
derated for the electrical consumption of the ash disposal systems. This
electricity is costed as purchased electricity to provide the same basis of
comparison in terms of electrical output.
The power plant is assumed to have a 30-year lifetime during which it
operates the equivalent of 165,000 hours at full load. A yearly operation of
5,500 hours at full load is assumed. All costs are based on full-load
operation. A heat rate of 9,500 Btu/kWh is used for both coals. Ash rates
are based on the as-fired ash content of the coal, assuming a ratio of 20%
bottom ash and 80% fly ash with no adjustment for pulverizer rejects or
slagging and fouling losses.
Ash Collection and Transportation
The designs used in development of the ash disposal systems are based on
use of standard components used by the utility industry and available from
equipment suppliers. The design and construction of the systems is assumed to
be integrated with the overall power plant design and construction. The ash
collection systems begin with the bottom ash and fly ash hoppers that receive
the ash from the boiler and the flue gas trains. All hopper, ash collection
and temporary storage, transportation, and disposal costs are included in the
overall ash disposal costs.
The following dry bulk densities and water contents are used.
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Dry bulk
density,
% moisture Ib/ft3
Base case: _1 2 2 4. 5 All
Ash in hoppers
Fly 0 0 0 0 0 50
Bottom _____ 45
Ash in pipelines
Fly 92.3 92.3 92.3 -
Bottom 92.3 92.3 92.3 83.3 83.3
Ash in trucks
Fly - - 25 10 0 80
Bottom - - 10 10 10 80
Ash in ponds
Fly 47 47 47 - - 55
Bottom 47 47 47 - - 55
Ash in landfills
Fly - - 17 17 17 90
Bottom - - 17 10 10 90
Disposal Sites
The disposal sites are sized for the life of the power plant. All land
is assumed purchased at the start of the project. All development costs
associated with the ponds and landfills are capitalized at the beginning of
the project. These include all construction which establishes or extends the
capacity of the facility such as clearing, topsoil removal, lining, grading,
dike construction, fencing and construction, and reclamation. Normal area-
fill landfill operational procedures are used, with topsoil removal, lining,
and reclamation proceeding during the course of its life.
In addition to the land occupied by the ponds or landfills, land is
provided for topsoil storage, working and maintenance functions, runoff
control, a 50-foot security perimeter, and roads. A 6-foot security fence,
lighting, and monitoring wells are also provided. Provisions are included for
reclamation that consists of topsoil replacement and revegetation.
Ponds consists of square excavated basins surrounded by earthen dikes
constructed of subsoil removed from the impoundment area. The depth and area
of the pond are calculated to minimize the sum of land and construction
costs. A typical pond cross-section is shown in Figure 4. Clearing is
assumed to be removal of a light growth of submature trees and grubbing. A 1-
1/2-foot layer of surface soil is removed and stockpiled. The dikes have a
stone-lined interior face, a graveled roadway on the top, and a topsoiled and
revegetated outer face. A diverter dike of similar construction extends three-
fourths of the pond width from one side to increase the flow distance from the
inlet to the overflow. A 1-foot-thick liner of compacted clay (not required
by regulations) is placed on the pond bottom and the interior faces of the
dikes. The clay is assumed locally available but to require hauling in the
course of placement.
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r'
WASTE DISPOSAL
POND
J
SUPERNATE SLURRY
IN
GROUND LEVEL —l
TOPSOIL
EXCAVATION
(1.5 FT.)
SECTION AA
POND PERIMETER DIKE
SECTION BB
POND DIVERTER DIKE
10% FREE BOARD
JL TOTAL
EXCAVATION DEPTH
SUBSOIL
EXCAVATION
10% FREE BOARD
DEPTH OF SLUDGE
1 TOTAL
EXCAVATION DEPTH
Figure 4. Pond dike construction details.
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The landfills are prepared, filled, and covered in increments of area to
form, when completed, a Square area-type fill with an edge height of 20 feet
and a maximum height at the center of 60 feet. A typical landfill cross
section is shown in Figure 5. The sides have a slope of 1 vertical to 2
horizontal and the top slopes up to the center at 2° (35 feet per 1000
feet). The landfill is surrounded by a 24-foot-wide perimeter ditch that
drains to a catchment basin for runoff control and monitoring. A 1-foot-thick
clay liner and a 2-foot-thick porous base of bottom ash that drains to the
catchment basin are provided. Reclamation consists of placing 1-1/2 feet of
surface soil over the completed portion of the landfill and revegetation.
Mobile Equipment
Mobile equipment requirements are based on the quantity, moisture
content, and bulk density of the ash and truck specifications and operating
profiles established for the specific operating conditions. Mobile equipment
operating data were obtained from published sources and information obtained
from manufacturers and suppliers. The truck sizes were selected to provide
flexibility of operation and a compromise of capital and operating costs for
the volume of ash involved. One spare truck is provided for each trucking
operation. Cycle times are based on a road speed of 30 mph for the specified
distance to the disposal site (0.75 mile for base case 3 and 1 mile for base
cases 4 and 5), an onsite speed of 15 mph, and estimated times for loading,
spotting, and dumping based on the type of ash:
Base case:
Flv ash Bottom ash
Distance, mi 1.5 2.0 2.0 2.0
Road time, min 34 4 4
Off-road time and
miscellaneous, min 22 24 £2 22
Total, min 36 28 56 26
Truck requirements for different ash quantities and cycle times are shown
in Figure 6. The requirements are based on 20-yd^-capacity trucks operating
16 hr/day during the power plant operating year of 5500 hr with 1 spare
truck per 2 trucks and ash with a dry bulk density of 1.08 tons/yd^.
ECONOMIC PREMISES
The economic premises establish criteria to determine capital costs for
construction of the ash disposal system and annual revenue requirements for
its operation. The premises are based on regulated utility economics and use
the design premises as a costing basis. The estimates use cost information
obtained from engineering-contracting and equipment companies and published
cost indexes. Equipment and labor costs are assumed equivalent to those in
the Midwest for all coal cases.
28
-------
10-ft Shelf
IS3
VO
50-ft Perimeter
6-ft
N Fence
Earth from
ditch
24~rt-wide
Ditch
2° slope up
to 60 ft max.
1-1/2-ft ToDsoil
2:1 Slope .^^_" - —
2-ft Bottom ash
-1-ft Clay
Figure 5. Landfill construction details.
-------
0--
250
-------
Capital Investment Estimates
Capital investment estimates for this study represent projects beginning
in early 1981 and ending in late 1983. Capital cash flows are assumed to be
25% in the first year, 50% in the second year, and 25% in the third year of
the project life. Capital costs for fixed assets are projected to mid-1982,
which represents the approximate midpoint of the construction expenditure
schedule. The estimates in this study are based on a process description,
flowsheet, material balance, and equipment list with sizing and materials of
construction. Other costs are scaled from the equipment costs. These study-
level estimates are considered to have a -20% to +40% range of absolute
accuracy and a relative accuracy for comparison between systems of
approximately 10%.
The total fixed capital investment consists of direct capital investment
for equipment, its installation, and its service facilities, indirect capital
investment for engineering, contracting, and construction expenses, and
contingency. The total capital investment consists of the total fixed capital
investment plus allowances for startup and modifications, royalties, the cost
of funds during construction, and the cost of land and working capital.
Direct Capital Investment--
Direct capital investment covers process equipment, piping, insulation,
transport lines, foundations, structures, electrical equipment,
instrumentation, site preparation and excavation, buildings, roads, trucks,
and earthmoving equipment. Direct investment costs are prepared using the
average annual Chemical Engineering cost indexes and projections as shown
below:
Year
1978
1979a 1980s 198ia 19823 1983a 1984a
Plant 218.8 240.2 259.4 278.9 299.8 322.3 344.9
Materialb 240.6 262.5 286.1 309.0 333.7 360.4 385.6
Laborc 185.9 209.7 226.5 244.6 264.2 285.3 305.3
a. TVA projections.
b. Same as index in Chemical Engineering (92) for "Equipment,
machinery, supports."
c. Same as index in Chemical Engineering (92) for "Construction
labor."
The overtime premium for 7% overtime is included in the construction
labor. Appropriate amounts for sales tax and for freight are included.
Costs for ponds and landfills are calculated using the cost factors shown
in Table 4.
31
-------
TABLE 4. POND AND LANDFILL UNIT COSTS
1982 $
Clearing 904.00/acre
Clay liner 3.50/yd3
Revegetation 0.70/yd^
Removal or replacement topsoil 2.68/yd^
Coarse gravel 11.37/yd^
Discharge channel 29.16/ft
Access road 5.05/ft
Security fence 17.50/ft
Monitoring wells 1,166.00 each
Office trailer 29,160.00 each
Dike construction 2.33/yd3
Underdrain blanket 0.00/yd^
Necessary electrical substations, conduit, steam, process water, fire and
service water, instrument air, chilled water, inert gas, and compressed air
distribution facilities are included in the utilities, services, and
miscellaneous direct investment. These facilities are costed as increments to
the facilities already required by the power plant. Service facilities such
as maintenance shops, stores, communications, security, offices, and roads are
estimated on the basis of process requirements. Services, utilities, and
miscellaneous costs will normally be in the range of 4% to 8% of the total
process capital depending on the type of process. A 4% rate is used in this
evaluation for all processes.
Indirect Capital Investment, Contingency, and Other Capital Investment—
Indirect capital investment covers engineering design and supervision,
architect and engineering contractor costs, construction costs, and contractor
fees. Construction facilities (which include costs for construction mobile
equipment, temporary lighting, construction roads, raw water supply,
construction safety and sanitary facilities) and other similar expenses
incurred during construction are considered as part of construction expenses
and are charged to indirect capital investment. A contingency of 10% is
included. The contingency is calculated as a percentage of the sum of the
direct and the indirect investments, less mobile equipment costs. Startup and
modification allowances are estimated at 8% of the total fixed investment
related to process equipment.
Interest during construction is 15.6% of the total fixed investment
excluding mobile equipment. This factor is equivalent to the 10% weighted
cost of capital assuming 25% of the construction expenditures in the first
32
-------
year, 50% the second year, and 25% the third year of the project construction
schedule. Expenditures are assumed uniform over each year. Startup costs are
assumed to occur late enough in the project schedule that there are no charges
for the use of money used to pay startup costs.
The percentages used for each type of proportioned investment are shown
in Table 5.
TABLE 5. PERCENTAGE FACTORS FOR PROPORTIONED INVESTMENTS
Mobile
equipment Process Pond Landfill
% of direct investment
Indirect Investment
Engineering design and supervision
Architect and engineering contractor
Construction expense
Contractor fees
Total indirect investment
0
0
0
0
6
3
10
_6
25
2
1
8
16
6
3
10
_6
25
Contingency
% of direct and indirect investment
0 10 10 10
% of total fixed investment
Other Investment
Allowance for startup and
modifications
Interest during construction
0
0
8
15.6
0
15.6
0
15.6
Working capital is the total amount of money invested in process
reagents, supplies, accounts receivable, and monies on deposit for payment of
operating expenses. Working capital is calculated as the equivalent of 1
month's process reagents, 1.5 months' conversion cost, and 1.5 months' plant
and administrative overhead costs. In addition, it includes an amount equal
to 3% of the total direct investment, excluding pond and landfill, to cover
spare parts, accounts receivable, and monies on deposit to pay taxes and
accounts payable.
33
-------
Annual Revenue Requirements
Annual revenue requirements use 1984 costs and are based on 5,500 hours
of operation per year at full load. Both first-year and levelized annual
revenue requirements are determined. Levelized annual revenue requirements
are based on a 10% per year discount factor and a 6% per year inflation rate
over the 30-year life of the power unit. Direct costs consist of raw
materials, labor, utilities, maintenance, and analytical costs. Indirect
costs consist of overheads and levelized capital charges.
Direct Costs—
Projected process reagent, labor, and utility costs are listed in
Table 6. Unit costs for electricity are based on the assumption that the
required energy is purchased from another source. Unit costs ($/kW,
mills/kWh) are calculated on the basis of adjusted gross power output of the
boiler excluding the electricity consumed by the ash disposal systems.
Actually, electrical use by the ash disposal system will result in a derating
of the utility plant. To minimize iterative calculations, the ash disposal
system is charged with purchased electricity instead of derating the utility
plant.
TABLE 6. PROJECTED 1984 UNIT COSTS FOR RAW
MATERIALS, LABOR, AND UTILITIES
$/unit
Process reagents
Limestone 8.50/ton
Lime 75.00/ton
Soda ash 160.00/ton
Sulfuric acid 65.00/ton
Labor
Operating labor 15.00/man-hr
Analyses 21.00/man-hr
Utilities
Water 0.014/kgal
Electricity 0.037/kWh
Diesel fuel 1.20/gal
Maintenance costs are estimated as a percentage of the direct investment,
based on type of equipment or facility. For process equipment maintenance
costs are 8%. Pipeline maintenance is 5%. Pond maintenance is 2%, landfill
maintenance is 3%, and mobile equipment maintenance is 10%.
Hourly fuel consumption is based on the equipment manufacturer's
specifications. For ash trucks 5 gal/hr is used. For dozers, front loaders,
34
-------
and compactors 2.9, 5.0 and 5.5. and 3.0 gal/hr, respectively, are used.
Total fuel consumption is based on the hourly rates and the operating hours of
the disposal site.
Indirect Costs--
Plant and administrative overhead is 60% of conversion costs less
utilities.
The capital structure and cost of capital for the electric utility
company is assumed to be:
Capital structure. % Cost of capital. %
Common stock 35 11.4
Preferred stock 15 10.0
Long-term debt 50 9.0
The weighted cost of capital, based on this capital structure, is 10.0%.
Depreciation for a 30-year economic life and a 30-year tax life for the
utility plant is expressed as a sinking fund factor. Salvage value is assumed
equal to removal costs. The annual sinking fund factor for a 30-year economic
life (nB) and 10.0% weighted cost of capital (WCC) is:
Sinking fund factor = - — - - = 0.61%
(1 + WCC) B-i
The use of the sinking fund factor does not suggest that regulated
utilities commonly use sinking fund depreciation. The sinking fund factor is
used because it is equivalent to straight- line depreciation levelized for the
economic life of the facility using the weighted cost of capital.
The levelized capital recovery factor is the weighted cost of capital
plus the sinking fund factor for depreciation.
An annual interim replacement allowance of 0.56% is also included as an
adjustment to the depreciation account to ensure that the initial investment
will be recovered within the actual rather than the forecasted life of the
facility. Since power plant retirements occur at different ages, an average
service life is estimated. Many different retirement dispersion patterns
occur. The type S-l Iowa State Retirement Dispersion pattern is used (91).
This S-l pattern is symmetrical with respect to the average-life axis and the
retirements are represented to occur at a low rate over many years. The
interim replacement allowance does not cover replacement of individual items
of equipment since these are covered by the maintenance charge.
Insurance and property taxes are assumed to be 2.50%.
35
-------
The levelized income tax is calculated as follows:
Levelized income tax = [CRFR + AIR-SLD] [1 - Debt ratio x debt costjr ITR j
WL»\_» J. "" J. J.K.
where: CRFg = Capital recovery factor
AIR = Allowance for interim replacement
SLD = Straight- line depreciation
ITR = Income tax rate
All terms are as decimal fractions
Using a 10.61% capital recovery factor (weighted cost of capital plus sinking
fund factor), 0.56% allowance for interim replacements, 3.3% straight- line
depreciation, 50% debt ratio, 9.0% debt cost, and a 50% income tax rate, the
levelized income tax rate is 4.31%.
The levelized investment tax credit is calculated as follows:
(CRFB) (Investment tax credit rate)
Levelized investment tax credit = - e - 7"i "'+" WCCl — Cl" - ITR") --- --
where CRFB, WCC, and ITR are the factors previously defined.
Using a 10.0% weighted cost of capital, 0.61% sinking fund factor, 10%
investment tax credit rate, 50% income tax rate, the annual levelized
investment tax credit is 1.92%.
For the accelerated tax depreciation credit, the sum of the years digits
method of accelerated depreciation is used for tax purposes. On a levelized
basis (using flow-through accounting) this results in a credit in the fixed
charge rate as follows:
2CRFB (nT - _1 _ )
Accelerated tax depreciation =
nT (nT + 1) (WCC)
where: CRFg = Capital recovery factor (weighted cost of capital
plus sinking fund factor) for the economic life
(as a decimal fraction)
CRFx = Capital recovery factor for the tax life
(as a decimal fraction)
nT = Tax life (in years)
Levelized accelerated depreciation credit = (ATD - SLD) x i -
where: ATD = Accelerated tax depreciation (as a decimal fraction)
SLD = Straight-line depreciation (as a decimal fraction)
ITR = Income tax rate (as a decimal fraction)
36
-------
For a 50% tax rate, 30-year tax and book life, 10.0% weighted cost of
capital, and 0.61% sinking fund factor, the annual levelized accelerated
depreciation credit is 1.36%.
The annual levelized capital charge consisting of all of the above
factors is shown below:
Capital charge* %
Capital recovery factor 10.61
Interim replacements 0.56
Insurance and property taxes 2.50
Levelized Federal and State
income tax 4.31
Investment tax credit (1.92)
Accelerated depreciation tax
credit (1.36)
Total 14.70
The annual capital charge is applied to the total capital investment. It
is recognized that land and working capital (except spare parts) are not
depreciable and that provisions must be made at the end of the economic life
of the facility to recover their capital value. In addition, investment
credit and accelerated depreciation credit cannot be taken for land and
working capital (except spare parts). The effect of these factors makes an
insignificant change in the annual capital charge rate and it is therefore
ignored.
37
-------
SYSTEMS ESTIMATED
The ash disposal methods evaluated in this study consist of five base
case processes representing major utility ash disposal practices. They are
based on the 500-MW dry bottom power unit described in the premises. Four of
the base cases are for the use of low-calcium 15.1% ash, 3.5% (dry basis)
sulfur eastern coal in which 49,630 Ib/hr of combined economizer, air heater,
and ESP ash and 12,480 Ib/hr of bottom ash are produced. The fly ash is
assumed to be nonhardening when wet. These four cases consist of (1) direct
sluicing of fly ash and bottom ash to separate ponds without water reuse (once-
through transportation water), (2) the same system with recycled
transportation water, (3) direct sluicing of fly ash and bottom ash to
temporary ponds, followed by excavation and trucking of both to a common
landfill, and (4) collection of dry fly ash in silos and bottom ash in
dewatering bins from which they are trucked moist to separate landfills.
The fifth base case represents a situation in which the power plant is
burning a western-type coal that contains about 1% calcium, making the fly ash
subject to spontaneous cementitious reactions when wet. The handling and
disposal system is designed to forestall these self-hardening reactions by
keeping the fly ash dry until it is placed in the disposal site. The coal in
this case contains 9.7% ash, producing 37,890 Ib/hr of combined economizer,
air heater, and ESP ash and 9,550 Ib/hr of bottom ash.
All of the systems are sized for intermittent removal of ash from the
collection hoppers. For the economizer, air-heater, and ESP fly ash system
the operating time is 12 hours in 24 hours. For the bottom ash system the
operating time is 6 hours in 24 hours. All flow rates in the material
balances are expressed as 24-hour averages, however. Intermittent flow rates
in the material balance are identified by footnote.
BASE CASE 1 - DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
This case consists of the simplest, and historically the most widely
used, ash disposal method. Water from any convenient large-volume source
(such as from once-through cooling water or directly from the power-plant
water intakes) is used to sluice both fly ash and bottom ash to disposal
ponds. The transportation water flows from the ponds, is treated to meet
NPDES pH requirements, and returns to the body of natural water from which it
came. In this case a river is assumed to be the water body. The flow
diagram, disposal site plan, and plot plan are shown in Figures 7, 8, and 9.
The material balance and equipment list are shown in Tables 7 and 8.
38
-------
ASH
IN COAL
ASH
HOPPER
OVERFLOW WATER
TO DISCHARGE
BOTTOM ASH POND
29
FAN
SOLIDS
FROM
WATER
TREATMENT
jfnri)i
Figure 7. Flow diagram. Base case 1, direct ponding of nonhardening ash without water
STACK
ASH
reuse.
-------
T
GROUNDWATER
FLOW
MONITORING
WELL^-I
1,924 FEET
6-FOOT SECURITY
FENCE
T
1,337 FEET
I
SLURRY
PIPELINES
\
INLET
BOTTOM ASH POND
1
,389,000 YD3
DISPOSAL VOLUME
1,699
K
1,215 FEET
FEET
DEPTH=
'4
c
DISCHARGE
WEIR
14.0 FEET
1,699 FEET
rUWtK KLAIN 1
TO PONDS , 1 MILE
\
li
** ^
TOPSOIL
STORAGE
.— 817 FEET —
OFFICE
TRAILER"
h
. — +•
REAGENTS — *^-
EQUIPMENT
^T" AREA
ACCESS ^
ROAD \
N j
£~
»
__,
INLET
MONITORING
WELL #2
| FLY ASH POND
5,537,000 YD3 3'° ' ' FEET
DISPOSAL VOLUME
2,193 FEET H
o
DISCHARGE
WEIR
i)EPTH= 1 7.3 FEET
3,01 1 FEET j-'
i_ MONITORING 5,209 FEET H
TO DISCHARGE WELL #4
T
MONITORING
WELL # 3
3,261 FEET
GROUNDWATER
FLOW TO RIVER
_L
TOTAL LAND AREA, 390 ACRES
Figure 8. Disposal site. Base case 1, direct ponding of nonhardening ash without water reuse.
-------
.FLY ASH AND BOTTOM ASH
SLURRY LINES TO PONDS , I MILE
cc
tu
Figure 9. Plot plan. Base case 1, direct ponding of nonhardening ash without
water reuse.
-------
TABLE 7. MATERIAL BALANCE
BASE CASE 1 - DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Stream No.
j
2
i
4
5
6
/
8
9
w
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
FtVmin^ 60°F
Gal/min
Percent solids
1
Coal ash
to furnace
62.400
62,400
2
Ash to
economizer
49.920
49,920
3
Ash collected
from economizer
1.560
1.560
4
Air intake to
economizer ash
pneumatic systeir
100
100
22
5
Economizer ash
in pneumatic
system
1 hfiO
1 Sfin
100
Stream No.
1
2
J
4
J
6
/
8
9
iiL
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
FtJ/min, 60°F
Gal/min
Percent solids
Ash to
air heater
48,360
48,360
1 7
Ash collected
from air heater
.,560
1,560
8
Economizer-air
heater ash in
pneumatic system
3.220
3,120
100
9
Ash to ESP
46,800
46,800
10
Air intake to
ESP ash
pneumatic system
1.390
1.390
303
Stream No.
1
i
J
4
5
(i
7
8
9
10
Description
Total stream. Ib/hr
Si-roam comnonents. Ib/hi
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Percent Solids
11
ESP ash in
meumatic system
47,900
46.510
1,390
12
Ash to FGD
system
285
285
13
Ash in FGD
waste
143
143
14
Ash to stack
142
142
15
Ash to
hydraulic
exhauster
51,120
49,630
1.490
Stream No.
1
i
i
4
b
6
;
8
9
IU
Description
Total stream. Ib/hr
Stream components, Ib/hi
Ash
Water
Air
Ft3/min. 60°F
Gal/min
Percent solids
16
Water to
hydraulic
exhauster3
595,600
595,600
1,190
17
Exhaust air
from hydraulic
exhauster3
1,490
1,490
325
18
Fly ash
slurry from
hydraulic
exhauster3
645,230
49.630
595,600
1,241
7.7
19
Fly ash
utilization
0
20
Overflow
water from
fly ash ponda
553,630
500
553,130
1,106
(continued)
42
-------
TABLE 7 (continued)
Description
1
•>
\
4
•i
h
7
H
9
10
St-ream components. Ib/hr
Ash
Water
Air
Ft3 /min. 60°F
Gal/min
21
Solids from
overflow water
treatment '
2.280
570
1,710
4
25
22
Settled fly
ash in
pond3
93.880
49,700
44,180
53
23
Water to bottom
ash hopper0
50,900
50,900
102
24
Slurry from
bottom ash
crusherb
63.380
12,480
50,900
114
20
25
Water to
bottom ash
slurryb
98,800
98,800
198
Description
1
2
t
4
5
h
7
8
q
10
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
Ft3/mln, 6QOF
Gal/min
Percent solids
26
Bottom ash
slurry from pump3
162,180
12,480
149,700
312
7.7
27
Bottom ash
utilization
0
28
Overflow
water from
bottom ash pond
138,830
120
138,710
278
29
Settled
bottom ash
in pond0
23,350
12,360
10,990
S3
30
Overflow water
to treatment3'0
692.460
620
691.840
1.384
Stream No.
Description
I
2
t
4
5
b
7
8
9
10
Tnral Kl-rp.sm, Ih/hr
Stream components, Ib/hi
Ash
Water
Air
H2S04
Ft3/min, 60°F
Gal/min
Percent solids
31
Reagents
20
20
0.02
32
Overflow water
to discharge '
690,200
50
690,150
1,380
33
Makeup water '
745.320
745.320
1.490
a. 24-hour average based on 12 hr/day operation for fly ash transport.
b. 24-hour average based on 6 hr/day operation for bottom ash transport.
43
-------
TABLE 8. EQUIPMENT LIST, DESCRIPTION, AND MATERIAL COST
BASE CASE 1 - DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Material cost,
delivered,
Item (number); description i 1982 k$
Area 1—Fly Ash Collection and Transfer
1. Economizer ash hoppers (4): Inverted pyramid-type hopper, 27
15 ft long x 15 ft wide x 16 ft deep, thermally isolated
design, constructed of 1/2-in. carbon steel
2. Air heater ash hoppers (4): Inverted pyramid-type
hopper, 15 ft long x 7 ft wide x 16 ft deep, constructed 21
of 1/2-in. carbon steel plate, insulated
3. ESP ash hoppers (32): Inverted pyramid-type hopper, 373
18 ft long x 12 ft wide x 16 ft deep, constructed of 1/2-
in. carbon steel plate, heat traced and insulated
4. Package-unit flv ash collecting and conveying system 228
comprising (1):
a. Vacuum pneumatic conveying lines for economizer-air
heater ash and ESP ash (2): Pipelines and pipe
fittings for vacuum pneumatic conveyance of fly ash,
25 ton/hr conveying capacity with 600-ft equivalent
length system, 6-in. I.D. branch lines and 8-in.
I.D. main lines, nickel-chromium cast iron pipe with
Ni-Hard® or equivalent pipe fittings
b. Fly ash and air inlet valves (40): Self-feeding
materials handling valve, electrically actuated, air
operated, 12-in. I.D. ash inlet, 6-in. I.D. ash outlet,
cast iron body, stainless steel slide gate; each
assembly includes two spring-loaded, air-inlet check
valves with cast iron bodies
c. Line segregating valves (10): Segregating slide
valve, electrically actuated, air operated for on-
off control of each branch conveying line, 6-in.
I.D. port, cast iron body, stainless steel slide gate
d. Vacuum breaker valves (2): Vacuum breaker valve for
control of vacuum in main conveying line to
hydraulic exhauster, 8-in. I.D. port, cast iron body
(continued)
44
-------
TABLE 8 (continued)
Material cost,
delivered.
Item (number); description 1982 k$
e. Hydraulic exhausters for vacuum pneumatic conveying
system (2): Vacuum producing hydraulic exhauster
with 8-in. I.D. air-ash inlet, 8-in. I.D. water
connection, and 10-in. I.D. discharge, cast iron body
with 250 psi water ejector head, chromium-iron alloy
air-ash inlet liner, stainless steel water nozzle
tips, ceramic-lined venturi throat; vertical
installation, tapped for vacuum and pressure gauges
f. System control unit (2): Automatic sequence control
unit to control the programmed operation of
materials handling valves, line segregating valves,
and water to the hydraulic exhauster; includes
gauges for manual reading and override switches for
manual operation
5. Water supply pumps for hydraulic exhausters (4+1 spare): 57
Centrifugal pump, 600 gpm, 480-ft head, carbon steel
body exhausters and impeller; 125 hp (costed 75% in Area
1 and 25% in Area 2)
Total. Area 1 706
Area 2—Fly Ash Conveyance to Disposal Site
1. Water supply pumps for fly ash conveyance (4+1 spare): 19
Same pumps as in Area 1, Item 5 (costed 25% in Area 2
and 75% conveyance in Area 1)
2. Air separator (1): Baffle-type cylindrical air separator 25
tank with cone bottom, dual 8-in. I.D. inlets and single
12-in. I.D. slurry outlet, 8-ft I.D. carbon steel shell
with 30-mm basalt lining
3. One-mile slurry pipeline to pond (1+1 spare): Pipeline (366)a
comprising 132 40-ft-long sections of flanged steel pond
pipe, 12-in. I.D., schedule 80 carbon steel and six
elbows or bends, 12-in. I.D. schedule 80 I.D. hardened
steel
Total. Area 2 44
(continued)
45
-------
TABLE 8 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
Area 3—Fly Ash Disposal Site
1. Fly ash pond (1): Pond, 3,011 ft square x 17.3 ft deep, (8,509)a
1-ft-thick clay liner, earthen perimeter dikes and 2,193-
ft-long divider dike graded on top for use as service
roads, pond area of 244 acres, pond volume of 5,537,000
yd3, topsoil storage of 12.2 acres contiguous with
topsoil storage for adjacent bottom ash pond, office
trailer and equipment storage area common for fly ash
and adjacent bottom ash pond, pond periphery monitored
by three monitoring wells, fly ash pond isolated by 6-ft-
high security fence which surrounds entire disposal site .
Total. Area 3 Q
Area 4—Fly Ash Water Treatment and Recycle of Water
(Posted 80% in Area 4 and_20Jg in Area 8)
1. Sulfuric_acid_s_t.QEage_t1a_n,k_..f_pr_,.pH. control of water to 2
discharge (1): Cylindrical steel tank 5 ft 7 in.
diameter x 5 ft 7 in. high, 1,000 gal, flat bottom
and closed flat top, carbon steel; all-weather housing
2. Metering pump for sulfuric acid (1+1 spare): Positive 2
displacement metering pump 0.01 to 1 gpm, 0 psig,
Carpenter 20® alloy or similar corrosion resistance to
93% sulfuric acid; 0.25 hp, flow rate controlled by a
pH controller
3. Agitator for mixing of treated water (1); Agitator with 3
24-in.-diameter nickel-chromium blade; 5 hp
4. Pump for solids slurry from water treatment (1+1 spare): 1
Centrifugal pump, 5 gpm, 20 psig, carbon steel body and
impeller, 0.25 hp
5. Automatic sampler for water to discharge (1): Automatic 4
sampler with sample size controlled by flow rate,
refrigerated storage of composite sample; all-weather
housing
Total. Area 4 L2_
(continued)
46
-------
TABLE 8 (continued)
Material cost,
delivered,
Item (number) ; description 1982 k$
Area 5-~Bottom Ash Collection and Transfer
1. Water supply pumps for bottom ash hopper and slurry (2 + 34
1 spare): Centrifugal pump, 600 gpm, 250-ft head,
carbon steel body hopper and slurry and impeller, 75 hp
2. Bottom ash hopper assembly (1): Double-V hopper with 352
3,320 ft3 capacity for 12-hr ash containment, supported
independently of furnace-boiler and mated to furnace
through a water seal trough spanning the furnace seal
plate, hopper body of 3/8-in.-thick carbon steel plate,
hopper lined with monolithic refractory 9 in. thick in
upper section and 6 in. thick in lower section, stainless
steel seal trough and overflow weirs, assembly includes
poke doors, lighted observation windows, access doors,
and hydraulically operated ash exit doors; each V-section
of hopper includes two hopper-type, double-roll grinders
with cast iron body and 10-in.-diameter x 2-ft-long
manganese steel rolls; 60 hp
Total. Area 5
Area 6—Bottom Ash Conveyance to Disposal Site
1. Slurry pumps for pipeline conveyance (1+1 spare): 57
Centrifugal slurry pump, 1,440 gpm, 350-ft head, Ni-Hard
liner and impeller, 250-hp motor
2. Shutoff and crossover valves (10): Air-operated gate 23
valve, 8-in. I.D. port, Ni-Hard
3. One-mile basalt-lined slurry pipeline to pond, normal (373)a
use (1): Pipeline comprising 294 18-ft-long sections of
flanged, basalt-lined steel pipe, 8 in. I.D. and six
basalt-lined elbows or bends, 8 in. I.D.
4. Spare slurry pipeline to pond (1): Pipeline comprising (93)a
132 40-ft-long sections of flanged steel pipe, 8 in.
I.D., schedule 80, carbon steel and six hardened steel
elbows or bends, 8 in. I.D.
(continued)
47
-------
TABLE 8 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
5. Pipeline agitators (2): Agitator with single horizontal 30
tooth roll, cast iron body, manganese steel roll and
wear plate; 25 hp
Total. Area 6 110
Area 7--Bottom Ash Disposal Site
1. - Bottom ash pond (1): Pond, 1,699 ft square x 14.0 ft (2,127)a
deep, with 1-ft-thick clay liner, earthen perimeter
dikes and 1,215-ft-long divider dike graded on top for
use as service roads, pond area of 85 acres, pond volume
of 1,389,000 yd3, topsoil storage of 3.1 acres
contiguous with topsoil storage for adjacent fly ash
pond, office trailer and equipment storage are common
for bottom ash and adjacent fly ash pond, pond periphery
monitored by two monitoring wells, bottom ash pond
isolated by 6-ft-high security fence which surrounds
entire disposal site
Total. Area 7
Area
1 .
2.
3.
4.
5.
8 — Bottom Ash Water Treatment and Recycle of Water
(Cos ted 20% in Area 8 and 80% in Area 4
Sulfuric acid storage tank for pH control of water to
discharge (1): Same tank as in Area 4, Item 1
Metering pump for sulfuric acid (1): Same pump as in
Area 4, Item 2
Agitator for mixing of treated water (1): Same agitator
as in Area 4, Item 3
Pump for solids slurrv from water treatment (1+1
spare) : Same pump as in Area 4, Item 4
Automatic sampler for water to discharge (1): Same
sampler as in Area 4, Item 5
Total. Area 8
Total, Base Case 1
0
0
0
0
1
3
1,261
.5
.5
.75
.25
a. Costs shown in parentheses are informational and are not included in
area or base case totals for equipment material costs.
48
-------
gravity into the slurry pipeline to the ash pond. The ejectors and separator
are mounted in the power-plant building structure to provide an 80-foot
gravity head at the separator tank outlet.
Bottom Ash Collection
Bottom ash is collected in a standard design double-vee-bottom steel
hopper with a 12-hour capacity. The hopper has a continuously sluiced
refractory lining and is connected to the boiler with a trough and plate water
seal to permit independent expansion and contraction. Each vee section feeds
a double-roll 10-inch-diameter by 2-foot-long clinker grinder. The clinker
grinders are connected to two 1,440 gpm ash transport pumps, one of which is a
spare. The pumps are connected to the primary and spare bottom ash pipelines
with manifolds to permit the use of either pump and either pipeline. Water
for the boiler-hopper seal, lining sluices, ash hopper sluices, and ash
transportation is provided by two 600 gpm centrifugal pumps fed by condenser
water or directly from the river water intake.
The system is designed to operate at about four times the bottom ash
production rate, permitting intermittent operation of about 2 hours per
shift when trouble free. When the ash hopper is to be emptied the feed door
to the clinker grinder is opened and the ash is sluiced through the clinker
grinders with water jets situated around the walls of the hopper. The water-
to-ash ratio of the slurry leaving the clinker grinder is about 5 to 1 by
weight. This slurry is drawn into the ash transport pump along with
sufficient additional water to reduce the slurry solids to 7.7%. The diluted
slurry is pumped into the transport line at an instantaneous rate of about
1,250 gpm.
Ash Transportation
Fly ash and bottom ash are transported one mile to the disposal ponds in
separate pipelines supported on concrete piers. The fly ash pipeline consists
of a 12-inch-diameter» flanged, schedule 80 carbon steel pipe on concrete
piers. The heavy schedule and hardened steel fittings are used to provide a
longer wear life. An identical spare line is provided.
The primary bottom ash pipeline consists of an 8-inch-diameter, flanged,
basalt-lined steel pipe on concrete piers. An 8-inch-diameter, schedule 80
carbon steel unlined spare with hardened steel fittings is also provided. An
intermediate agitator is situated in each bottom ash pipeline to reduce
settling.
Ash Ponds
The fly ash and bottom ash pipelines discharge into separate contiguous
earthern-diked square ponds constructed as described in the premises. Both
ponds are sized for the life of the power plant using a 55 lb/ft3 dry bulk
density for both ashes. The fly ash pond is about 3,000 feet square from dike
crest to dike crest, occupies about 200 contained acres, has a 5.5 million
yd3 disposal volume, and is designed for a 17-foot ash depth when full. The
bottom ash pond is about 1,700 feet square from crest to crest, occupies about
60 acres, has a 1.4 million yd3 disposal volume, and is designed for a 14-
foot ash depth when full.
50
-------
Fly Ash Collection
Economizer, air heater, and ESP ash are collected in hoppers beneath the
units. The ash is removed intermittently by a vacuum pneumatic conveying
system with hydraulic exhausters. The ash-air-water mixture from the
exhausters is discharged into an air separator from which the ash-water
suspension flows by gravity through a transport line to the ash pond.
The ash hoppers have a 12-hour-capacity and are constructed of plate
steel in the form of an inverted pyramid. An ash valve at the bottom connects
to the ash conveying system. Four hoppers each are used for the economizer
and air heater ash and 32 hoppers are used for the ESP ash. The air heater
and ESP hoppers connect directly to the bottom of the units. The economizer
hoppers are thermally isolated from the economizer flue gas by a throat and
chute to prevent sintering of the ash. The air heater and ESP hoppers are
insulated to maintain the interior temperature above the sulfuric acid and
water saturation temperatures of the flue gas. The ESP hoppers are also
electrically heated for the same reason. Condensation in the hoppers can
cause caking or freezing that hinders ash removal.
Two hydraulic exhausters are used. Each is supplied with 1,190 gpm of
water at 250 psig by 2 centrifugal pumps. The exhausters consist of cast iron
frames with 8-inch-diameter air inlets and 10-inch-diameter outlets. The
water is ejected through annular nozzles above a basalt-lined venturi throat,
producing a design vacuum of 19 in. Hg at the air inlet.
The ash vacuum pneumatic conveying system consists of two 8-inch-diameter
main lines and 6-inch-diameter secondary lines to the ash and inlet air valves
on the ash hoppers. Each main line is connected to half of the ash hoppers.
Both of the main lines can be valved to either ejector so that ash can be
removed from all hoppers by either ejector. Vacuum breakers on the main lines
prevent backflow during shutdowns.
The system is designed for operation at 50 tons/hr, twice the maximum ash
production rate, with both ejectors operating. In normal operation both
ejectors are operated about one-half of the time. The hoppers•are emptied
sequentially by a programmed control system. Segregation valves on the
secondary lines isolate inactive lines. The ash flow rate from the hoppers is
controlled by the ash valve which admits controlled quantities of air and ash
to the conveying line. The ash rate is automatically controlled to maintain a
preset vacuum level at the valve, thus ensuring the most efficient ash-to-air
ratio and air velocity. The valve is automatically closed when a large
decrease in vacuum indicates an empty hopper and the system is automatically
shifted to the next hopper in the sequence. The system is designed for a
maximum equivalent conveying length of 600 feet. The design velocity is about
1,800 ft/min with a 19 in. Hg vacuum at the ejector. All piping and fittings
are of abrasion-resistant materials.
The hydraulic exhausters are mounted just above a baffle-type air
separator tank and the ash-air-water mixture from the exhausters is injected
into opposite sides of the tank. The air separated from the mixture is vented
to the atmosphere and the ash-water slurry, composed of 7.7% solids, flows by
49
-------
The total disposal area occupies 390 acres. In addition to the area
occupied by the dikes, this includes the perimeter, topsoil storage, an office
and equipment area, and roadways. The entire disposal area is fenced and it
is provided with electricity, water, and sewer facilities. Four ground water
monitoring wells are also provided.
The ash slurries are discharged onto riprap at a corner of their
respective ponds on the side closed by the diverter dike. Overflow intakes
are situated on the opposite side of the diverter dike. The slurry is thus
forced to flow around the diverter dike to reach the water outlet, allowing
increased area, reduced velocity, and time for the ash to settle. The
overflow intakes are surrounded by floating skimmer weirs to prevent floating
ash from entering the intakes.
The overflows from both ponds discharge through pipes into a single rock-
lined outflow channel that returns the water to the river. A section of
concrete channel is provided for additional skimmers, pH monitoring, and a
Parshall flume for flow rate monitoring. The pH is adjusted automatically, if
above 9, by addition of sulfuric acid. Periodically, solids are manually
removed from the channel, reslurried, and pumped back to the fly ash pond.
The 24-hour average flow rate of fly ash slurry entering the fly ash pond
is 1,200 gal/min and the maximum instantaneous rate is 2,500 gal/min. The 24-
hour average flow rate through the overflow is 1,100 gal/min. The 24-hour
average flow rate of bottom ash slurry entering the bottom ash pond is about
300 gal/min and the maximum instantaneous rate is about 1,200 gal/min. The 24-
hour average flow rate through the overflow is about 280 gal/min. The
combined overflow streams have a 24-hour average flow rate of about 1,400
gal/min. The pond filling rates, based on the 55 Ib/ft3 dry bulk density,
are 800 yd-Vday for fly ash and 200 yd^/day for bottom ash.
BASE CASE 2 - DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
This case is essentially the same as base case 1 except that the pond
overflow water is recycled. The use of water recycle can represent either a
limited water supply or a necessity to meet pollutant discharge limitations,
although the latter is a more common application. The flow diagram, disposal
site plan, and plot plan are shown in Figures 10, 11, and 12. The material
balance and equipment list are shown in Tables 9 and 10.
The same fly ash and bottom ash collection, transportation, and ponding
procedures are used in this base case as are used in base case 1. The base
case 1 process, equipment, and pond site descriptions also apply to this base
case. In this base case, however, the pond overflow is pumped back to a
storage tank at the power plant for reuse as transportation water. A portion
of the water returned from the ponds is treated to reduce its hardness. This,
along with replacement of the water lost in the settled ash is assumed to
control scaling.
The fly ash and bottom ash are collected and transported to the pond with
equipment and procedures identical to those described in base case 1. The
51
-------
t_n
t-0
™™*T STACK
FAN ASH
SOLIDS
FROM
WATER
TREATMENT
Figure 10. Flow diagram. Base case 2, direct ponding of nonhardening ash with water reuse.
-------
SLURRY ^
PIPELINES
RETURN -x"
WATER LINE ^
[-
j
t
I
GROUNDWATER
FLOW
MONITORING t
WELL # 1
1,924 FEET
6-FOOT SECURITY
FENCE
1
i'L
1,337 FEET'
k L_
* (
1 *T
BOTTOM ASH POND
1,389,000 YD3
DISPOSAL VOLUME
K- 1,215 FEET
INLET
c
1,699 FEET DISCHARGE
WEIR
DEPTH=I4.0 FEET
-i 1,699 FEET
T
\
I
-i
REAGE
-r^™ CHEMICAL 0
TOPSpIL STORAGE^
STORAGE BUILDING
COLD to
LIME SO
— 817 FEET —
pni IIPMFWT
DFFICE »T- AREA
RAILER"^ -1
h
NTS _o
1 — MT
'ATER
FTENER
POWtR PLANT
TO PONDS ,1 MILE
ACCESS J
ROAD \
K - ) .
| x
£
, ,f
INLET '
MONITORING
WELL #2
1 FLY ASH POND
5,537.000 YD3 3'° ' ' FEET
DISPOSAL VOLUME
r- 2,193 FEET H
JO
DISCHARGE
WEIR
DEPTH= 1 7.3 FEET
3,01 1 FEET j-
T
MONITORING
WELL ^ 3
3,261 FEET
GROUNDWATER
FLOW TO RIVER
1
MONITORING H
WELL # 4
TOTAL LAND AREA, 390 ACRES
Figure 11. Disposal site. Base case 2, direct ponding of nonhardening ash with water reuse.
-------
Ul
-p-
FUTURE
ROAD
FLY ASH AND BOTTOM ASH
SLURRY LINES TO PONDS . I MILE
_ RETURN WATER LINE
FROM TREATMENT . I MILE
Figure 12. Plot plan. Base case 2, direct ponding of nonhardening ash with water reuse,
-------
TABLE 9. MATERIAL BALANCE !'
BASE CASE 2 - DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Stream No.
Description
I
2
i
4
5
6
7
8
9
JO
Total stream. Ib/hr
Stream components, Ib/hr
Ash
Water
Air
Ft3/min, 60°F
Gal /m in
Percent solids
1
Coal ash
to furnace
62.400
62,400
2
Ash to
economizer
49,920
49,920
3
Ash collected
from economizer
1.560
1.560
4
Air intake to
economizer ash
pneumatic svsten
100
100
22
5
Economizer ash
in pneumatic
system
1.660
1.560
100
Stream No.
1
i
1
4
5
6
7
8
9
10
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Percent solids
6
Ash to
air heater
48,360
48,360
7
Ash collected
from air heater
1,560
1,560
8
Economizer-air
heater ash in
pneumatic system
3,220
3,120
100
9
Ash to ESP
46,800
46,800
10
Air intake to
ESP ash
pneumatic systen
1,390
1,390
303
Stream No.
1
i
i
4
5
6
7
8
9
IU
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Percent solids
11
ESP ash in
pneumatic system
47.900
46.510
1,390
12
Ash to FGD
system
285
285
13
Ash in FGD
waste
143
143
14
Ash to stack
142
14?
15
Ash to
hydraulic
exhauster
51,120
49 filO
1,490
Stream No.
1
1
)
4
b
6
/
H
9
IU
Description
Total stream, Ib/hr
Stream components. Ib/h
Ash
Water
Air
Ft3/min. 60°F
Gal/min
Percent solids
16
Water to
hydraulic
exhauster
595.640
40
595.600
1,190
17
Exhaus t air
from hydraulic
exhauster
1,490
1.490
325
18
Fly ash
slurry from
hydraulic
exhauster
645.270
49.630
595,600
1,241
7 7
19
Fly ash
utilization
0
20
Overflow
water from
fly ash pond
553,630
500
553,130
1,106
(continued)
55
-------
TABLE 9 (continued)
Stream No.
Description
1
2
j
4
5
b
7
8
9
10
Tnf.al stream. Ib/hr
Stream components, Ib/hr
Ash
Water
Air
Ft3/min. 60°F
^ Gal/min
Percent solids
21
Solids from
overflow water
treatment
2,280
570
1,710
It
25
22
Settled fly
ash in
pond
93,950
49,740
44,210
53
23
Water to bottom
ash hopper
50,900
3
50,900
102
24
Slurry from
bottom ash
crusher
63,380
12,480
50,900
114
20
25
Water to
bottom ash
slurry
98,810
7
98,800
198
Stream No.
Description
1
2
J
4
b
6
7
8
9
10
Total stream, Ib/hr
Stream components, Ib/h
Ash
Water
Air
FtVmin. 60°F
Gal /miti
Percent solids
26
Bottom ash
slurry from pump
162,190
12,490
149,700
312
7.7
27
Bottom ash
utilization
0
28
Overflow
water from
bottom ash pond
138,830
120
138,710
278
29
Settled
bottom ash
in pond
23,360
12,370
10,990
•;•!
30
Overflow water
to treatment
692,460
620
691,840
1,384
Stream No.
Description
1
2
3
4
5
6
7
8
9
10
Total stream, Ib/hr
Stream components, Ib/h:
Ash
Water
Air
H?SOi
Ft3/minj 60°F
Gal/min
Percent solids
31
Water
treatment
reagents
100
100
0.1
32
Water recycle
to plant
690,280
50
690,230
1,380
33
Makeup water
55,070
55,0/0
1IU
56
^life^^jlp^
-------
TABLE 10. EQUIPMENT LIST, DESCRIPTION, AND MATERIAL COST
BASE CASE 2 - DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Material cost,
delivered,
Item (number); description 1982 k$
Area l--Fly Ash Collection and Transfer
1. Economizer ash hoppers (4): Inverted pyramid-type 27
hopper, 15 ft long x 15 ft wide x 16 ft deep, thermally
isolated design, constructed of 1/2-in. carbon steel
plate
2. Air heater ash hoppers (4): Inverted pyramid-type hopper, 21
15 ft long x 7 ft wide x 16 ft deep, constructed of 1/2-
in. carbon steel plate, insulated
3. ESP ash hoppers (32): Inverted pyramid-type hopper, 373
18 ft long x 12 ft wide x 16 ft deep, constructed of 1/2-
in. carbon steel plate, heat traced and insulated
4. Package-unit fly ash collecting and conveying system 228
comprisng (1):
a. Vacuum pneumatic conveying lines for economizer~air
heater ash and ESP ash (2): Pipelines and pipe
fittings for vacuum pneumatic conveyance of fly ash,
25 ton/hr conveying capacity with 600-ft equivalent
length system, 6-in. I.D. branch lines and 8-in. I.D.
main lines, nickel-chromium cast iron pipe with Ni-
Hard® or equivalent pipe fittings
b. Fly ash and air inlet valves (40): Self-feeding
materials handling valve, electrically actuated, air
operated, 12-in. I.D. ash inlet, 6-in. I.D. ash out-
let, cast iron body, stainless steel slide gate; each
assembly includes two spring-loaded, air-inlet check
valves with cast iron bodies
c. Line segregating valves (10): Segregating slide
valve, electrically actuated, air operated for on-
off control of each branch conveying line, 6-in. I.D.
port, cast iron body, stainless steel slide gate
d. Vacuum breaker valves (2): Vacuum breaker valve for
control of vacuum in main conveying line to hydraulic
exhauster, 8-in. I.D. port, cast iron body
(continued)
57
-------
TABLE 10 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
e. Hydraulic exhausters for vacuum pneumatic conveying
system (2): Vacuum producing hydraulic exhauster
with 8-in. I.D. air-ash inlet, 8-in. I.D. water
connection, and 10-in. I.D. discharge, cast iron body
with 250 psi water ejector head, chromium-iron alloy
air-ash inlet liner, stainless steel water nozzle
tips, ceramic-lined venturi throat; vertical
installation, tapped for vacuum and pressure gauges
f. System control unit (2): Automatic sequence control
unit to control the programmed operation of
materials handling valves, line segregating valves,
and water to the hydraulic exhauster; includes
gauges for manual reading and override switches for
manual operation
5. Water supply pumps for hydraulic exhausters (4+1 57
spare): Centrifugal pump, 600 gpm, 480-ft head, carbon
steel body and impeller; 125 hp (costed 75% in Area 1
and 25% in Area 2)
Total. Area 1
Area 2--Fly Ash Conveyance to Disposal Site
1. Water supply pumps for fly ash conveyance (4+1 spare): 19
Same pumps as in Area 1, Item 5 (costed 25% in Area 2
and 75% in Area 1)
2. Air separator (1): Baffle-type cylindrical air separator 25
tank with cone bottom, dual 8-in. I.D. inlets and single
12-in. I.D. slurry outlet, 8-ft I.D. carbon steel shell
with 30-mm basalt lining
3. One-mile slurrv pipeline to pond (1+1 spare): Pipe- (366)a
line comprising 132 40-ft-long sections of flanged steel
pipe, 12-in. I.D., schedule 80 carbon steel and six elbows
or bends, 12-in. I.D., schedule 80 I.D. hardened steel
Total. Area 2 44
(continued)
58
-------
TABLE 10 (continued)
Material cost,
delivered,
Item (number): description 1992 k$
Area 3—Fly Ash Disposal Site
1. Fly ash pond (1): Pond, 3,011 ft square x 17.3 ft deep, (8,509)a
1-ft-thick clay liner, earthen perimeter dikes and 2,193-
ft-long divider dike graded on top for use as service
roads, pond area of 244 acres, pond volume of 5,537,000
yd3, topsoil storage of 12.2 acres contiguous with
topsoil storage for adjacent bottom ash pond, office
trailer and equipment storage area common for fly ash
and adjacent bottom ash pond, pond periphery monitored
by three monitoring wells, fly ash pond isolated by 6-ft-
high security fence which surrounds entire disposal site
Total. Area 3 Q
Area 4--Fly Ash Water Treatment and Recycle of Water
(Costed 80% in Area 4 and 20% in Area 8)
1. Sulfuric acid storage tank for pH control of water to 2
discharge (1): Cylindrical steel tank 5 ft 7 in.
diameter x 5 ft 7 in. high, 1,000 gal, flat bottom and
closed flat top, carbon steel; all-weather housing
2. Metering pump for sulfuric acid (1+1 spare); Positive 2
displacement metering pump 0.01 to 1 gpm, 0 psig,
Carpenter 20® alloy or similar corrosion resistance to
93% sulfuric acid; 0.25 hp flow rate controlled by a pH
controller
3. Agitator for mixing of treated water (1): Agitator with 3
24-in.-diameter nickel-chromium blade; 5 hp
4. Pump for solids slurry from water treatment (1+1 1
spare): Centrifugal pump, 5 gpm, 20 psig, 1 carbon
steel body and impeller, 0.25 hp
5. Chemical storage and preparation facility (1): Building 32
25 ft x 25 ft for storage and preparation of lime and
soda ash water softening agents; includes concrete
floor, storage bins, and 1,000 gal makeup and slaking
tank with agitator; 10 hp
6. Package-unit water softener (1): Cold lime water 50
softening unit, 34 ft long x 12 ft wide, 460 gpm
capacity, carbon steel, 2 hp
(continued)
59
-------
TABLE 10 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
7. Pumps for return water to plant (2): Centrifugal pump, 21
800 gpm, 200-ft head, carbon steel body and impeller; 75
hp
8. Return water pipeline (1): One-mile pipeline of welded (120)a
steel pipe including six elbows or bends, 12 in. I.D.,
schedule 40 carbon steel
9. Return water storage tank (1): Cylindrical steel tank, 44
50 ft diameter x 25 ft high, 370,000 gal capacity, open
top, flat bottom, carbon steel
Total. Area 4 155
Area 5—Bottom Ash Collection and Transfer
1. Water supply pumps for bottom ash hopper and slurry (2 + 34
1 spare): Centrifugal pump, 600 gpm, 250-ft head,
carbon steel body and impeller, 75 hp
2. Bottom ash hopper assembly (1): Double-V hopper with 352
3,320 ft3 capacity for 12-hr ash containment, supported
independently of furnace-boiler and mated to furnace
through a water seal trough spanning the furnace seal
plate, hopper body of 3/8-in.-thick carbon steel plate,
hopper lined with monolithic refractory 9 in. thick in
upper section and 6 in. thick in lower section, stainless
steel seal trough and overflow weirs, assembly includes
poke doors, lighted observation windows, access doors and
hydraulically operated ash exit doors; each V-section of
hopper includes two hopper-type, double-roll grinders
with cast iron body and 10-in.-diameter x 2-ft-long
manganese steel rolls; 60 hp
Total. Area 5 386
Area 6—Bottom Ash Conveyance to Disposal Site
1. Slurry pumps for pipeline conveyance (1+1 spare): 57
Centrifugal slurry pump, 1,440 gpm, 350-ft head, Ni-Hard
liner and impeller, 250-hp motor
2. Shutoff and crossover valves (10); Air-operated gate 23
valve, 8-in. I.D. port, Ni-Hard
(continued)
60
-------
TABLE 10 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
3. One-mile basalt-lined slurry pipeline to pond, normal (373)a
use (1): Pipeline comprising 294 18-ft-long sections of
flanged, basalt-lined steel pipe, 8 in. I.D. and six
basalt-lined elbows or bends, 8 in. I.D.
4. Spare slurry pipeline to pond (1): Pipeline comprising (93)a
132 40-ft-long sections of flanged steel pipe, 8 in.
I.D.t schedule 80, carbon steel and six hardened steel
elbows or bends, 8 in. I.D.
5. Pipeline agitators (2): Agitator with single horizontal 30
tooth roll, cast iron body, manganese steel roll and
wear plate; 25 hp
Area 6 1JJL
Area 7--Bottom Ash Disposal Site
1. Bottom ash pond (1): Pond, 1,699 ft square x 14.0 ft (2,127)a
deep, with 1-ft-thick clay liner, earthen perimeter
dikes and 1,215-ft-long divider dike graded on top for
use as service roads, pond area of 85 acres, pond volume
of 1,389,000 yd3, topsoil storage of 3.1 acres
contiguous with topsoil storage for adjacent fly ash
pond, office trailer and equipment storage are common
for bottom ash and adjacent fly ash pond, pond periphery
monitored by two monitoring wells, bottom ash pond
isolated by 6-ft-high security fence which surrounds
entire disposal site
Total. Area 7 0
Area 8—Bottom Ash Water Treatment and Recycle of Water
(Posted 20% in Area 8 and 80% in Area 4)
1. Sulfuric acid storage tank for pH control of water to 0.5
discharge (1): Same tank as in Area 4, Item 1
2. Metering pump for sulfuric acid (1): Same tank as in 0.5
Area 4, Item 2
3. Agitator for mixing of treated water (1): Same agitator 0.75
as in Area 4, Item 3
(continued)
61
-------
TABLE 10 (continued)
Material
cost,
delivered,
Item
4.
5.
6.
7.
8.
9.
(number) : description
Pump for solids slurrv from water treatment (1+1
spare): Same pump as in Area 4, Item 4
Chemical storage and preparation facility (1): Same
building as in Area 4, Item 5
Package-unit water softener (1): Same softener as in
Area 4, Item 6
Pumps for return water to plant (2): Same pumps as in
Area 4, Item 7
Return water pipeline (1): Same pipeline as in Area 4,
Item 8
Return water storage tank (1): Same tank as in Area 4,
Item 9
Total. Area 8
Total, Base Case 2
1982
0.
8
13
5
(30)
11
39
1,440
k$
25
a
a. Costs shown in parentheses are informational and are not included in
area or base case totals for equipment material costs.
62
-------
water supplied to the fly ash hydraulic exhausters and the bottom ash hopper
and sluicing pump is obtained from a hold tank containing recycled pond water
and makeup water.
Ash Ponds
The same pond design and operation is used, as in base case 1. After
flowing through the pH treatment flume* however, the water is collected in a
catchment basin. Four-fifths of the water is pumped directly back to the
power plant through a 12-inch steel pipeline. One-fifth of the water is
passed through a package-unit water treatment plant at the pond site before
entering the pipeline. The plant is essentially a cold lime - soda ash system
designed primarily to reduce gypsum hardness and avoid scaling. Metered
quantities of lime and soda ash are mixed with the water to reduce the calcium
content by 90%. An initial 500 mg/L calcium concentration is assumed for the
pond effluent, based on TVA data (80). About 275 gpm of water is treated on a
24-hour average but the water treatment plant is sized for 460 gpm to
accommodate the higher peak loads associated with £he intermittent ash
transportation cycles. In all, a 24-hour average of about 1,400 gpm of water,
including treated and untreated water, is returned to the ash transportation
system.
The returned water is stored in a 370,000 gallon surge tank, providing a
capacity of about 4-1/2 hours at average rates and about 2 hours for
simultaneous transportation of fly ash and bottom ash. Water trapped in the
settled sediments of the ash pond constitutes about 7% of the transportation
requirements. This water is replaced with water from the power plant river
water intakes.
BASE CASE 3 - HOLDING PONDS AND LANDFILL FOR NONHARDENING ASH
Base case 3 represents a disposal practice in which wet sluicing and
ponding is used for initial ash collection, followed by dredging, draining,
and landfill disposal of the ponded ash. This practice can be used if
construction of large ponds is impractical or undesirable. Typical
applications are for power plants that have limited available land and have
exhausted existing ponds or have added new units. The flow diagram, disposal
site plan, and plot plan for base case 3 are shown in Figures 13, 14, and 15.
The material balance is shown in Table 11 and the equipment list is shown in
Table 12.
In this base case the ash collection method and transportation to the
ponds are the same as those used in base case 1 except that the ponds are one-
fourth mile from the power plant. The fly ash is collected from the hoppers
with a vacuum pneumatic conveying system using hydraulic exhausters and flows
by gravity to the fly ash pond. In base case 3, the shorter conveying
distance to the pond permits a lower elevation for the hydraulic exhausters
and air separator and a lower head pressure for their water supply pumps.
Bottom ash is sluiced from the bottom ash hoppers and pumped to the bottom ash
pond using a jet pump. The jet pump is used instead of a centrifugal pump
63
-------
ELECTROSTATIC
PRECIPITATOR
FAN STACK
ASH
1/4-MILE LONG LINE
BOTTOM ASH
TRANSFER STATION
FLY ASH
TRANSFER STATION
RECYCLE TO POND
REAGENTS
BOTTOM ASH POND
28
3B RECYCLE TO LANDFILL REAGENTS
COMMON LANDFILL
OVERFLOW WATER
TO DISCHARGE
DISCHARGE
Figure 13. Flow diagram. Base case 3, holding ponds and landfill for nonhardening ash.
-------
POWER PLANT TO PONDS, I /4 MILE
T
MONITORING WELL—•
#1
094 FEET
664 FEET
_L
GROUNDWATER FLOW
SLURRY
PIPELINES
INLET
BOTTOM ASH POND
|«-536 FEET-f-
233,000 YD3 *-
VOLUME
DEPTH I 1.8 FEET
REAGENTS o-
ACCESS
ROAD
INLET
FLY ASH POND
937,000 YD3
VOLUME
"—MONITORING WELL #2
1,020 FEET
DEWATERING BASINS /]
DEPTH 5.0 FEET
DEPTH 15.0 FEET
2,676 FEET MONITORING WELL
TO DISCHARGE
T
8|MONITORING WELL
1,658 FEET
_L
REAGENTS
257 FEET
POND TO LANDFILL, 3/4 MILE
MONITORING WELL
STORAGE
6-FOOT SECURITY FENCE
TOPSOIL
STORAGE
TO DISCHARGE
MONITORING WELL #5
SOLIDS FROM WATER TREATMENT
CATCHMENT DITCH-24 FEET WIDE
COMMON LANDFILL
3,5 I 2,000 YD3
VOLUME
1,841 FEET
2,390 FEET
GROUNDWATER
FLOW TO RIVER
T
1,989 FEET
MONITORING WELL #6
TOTAL DISPOSAL SITE AREA, 2 I 2 ACRES
TOTAL POND SITE AREA, I 02 ACRES
TOTAL LANDFILL SITE AREA, I 10 ACRES
Figure 14. Disposal site. Base case 3, holding ponds and landfill for
nonhardening ash.
65
-------
•1 *. fr,*S3^m>S9S8^3m-S*><81>&:?!ir:{-i=5*
99
H-
cw
l-i
Ul
03
CD
tB
n
01
CD
n>
OJ
cr
o
00
a,
en
B
ROAD
r
ROAD
§
B-
§
H-
3
oq
PUMP
STATION
RIVER
DOCK
en
-------
TABLE 11. MATERIAL BALANCE
BASE CASE 3 - HOLDING PONDS AND LANDFILL FOR NONHARDENING ASH
1
i
1
I,
5
h
7
8
9
JO
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
FtJ/min, 60°F
Gal/min
Percent solids
1
Coal ash
to furnace
62,400
62,400
2
Ash to
economizer
49,920
49,920
J
Ash collected
from economizer
1,560
1,560
4
Air intake to
economizer ash
pneumatic system
100
100
22
5
Economizer ash
in pneumatic
system
1,660
1,560
100
1
i
i
4
')
6
/
8
9
ifi.
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
Ft3/roin 60°F
Gal/min
Percent solids
6
Ash to
air heater
48,360
48, JbU
7
Ash collected
from air heater
i,^bU
i,b6U
5
Economizer -air
heater ash in
pneumatic system
3,220
3,120
100
9
Ash to ESP
46,800
46,800
10
Air intake
to ESP ash
pneumatic systen
1,390
Ij390
303
i
i
>
4
')
b
/
«
9
10
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Percent solids
11
ESP ash in
meumatic system
47,900
46,510
1,390
12
Ash to FGD
system
285
285
13
Ash in FGD
waste
143
143
14
Ash to stack
142
142
15
Ash to
hydraulic
exhauster
51,120
49,630
1,490
1
I
!
4
•i
fi
/
H
SI
IU
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
FtJ/min 60°F
Gal/min
Percent
16
Water to
hydraulic
exhauster
595,600
59i,bOO
1,190
17
Exhaust air
from hydraulic
exhauster
1,490
1,490
H2i
18
Fly ash
slurry from
hydraulic
exhauster
645,230
49,630
595,600
1,241
"1.1
19
Fly ash
utilization
U
20
Overflow
water from
fly ash pond
581,240
500
580,740
1,162
(continued)
67
-------
TABLE 11 (continued)
1
i
i
4
5
6
7
8
9
10
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
Ft3/min, 6QOF
Gal/min
Percent solids
21
Settled fly
ash in pond
93,880
49,700
44,180
53
22
Water to botton
ash hopper
50,900
50,900
102
23
Slurry
from bottom
ash crusher
' 63,380
12,480
50,900
114
20
24
Water to
jet pump
98,800
98,800
198
?5
Bottom ash
slurry from pump
162,180
LZ,4t4U
149,700
312
/. /
1
2
1
4
5
6
7
8
9
IQ
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Plater
Air
H2SU^
FtJ/min, 60°F
Gal/min
Percent solids
2b
Bottom ash
utilization
0
•il
Overflow
water from
bottom ash pond
148,450
120
148,330
297
* 28
Settled bottom
ash in pond
23,350
12,360
10,990
53
29
Overflow water
to treatment
729,690
620
729,070
1,460
30
Reagents
20
ZU
U.UZ
1
2
t
4
5
6
7
8
9
10
Stream No.
Description
Total stream, Ib/hr
Stream components. Ib/hr
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Pprrent solids
31
Pond
overflow water
to discharge
729,390
50
727,340
1,455
32
Makeup water
745,300
/45, JUO
1,491
33
Combined ash
to landfill
""" 80,000
62,060
17,940
78
34
Common landfill
74,470
62,060
12,410
83
35
Rainfall
to landfill
84,610
84,610
169
1
2
i
4
5
6
7
a
9
10
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
H2S04
Ft^/min, 60°F
Gal/min
Percent solids
36
Landfill
runoff water
to treatment
91 ,900
50
91,850
174
37 [ 38
Reagents |
for landfill { Solids from
water treatments water treatment
i
60 f 1,760
!
( 45
I 1,710
i
60 ,
s
0.06 | 4
!
39
Treated
landfill runoff
to discharge
90,200
5
90,20U
180
40
Solids
from overflow
treatment
L , zeu
VU
1,710
4
(continued)
68
-------
TABLE 11 (continued)
f
1
4
5
6
7
8
9
10
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
FtJ/min, 60°F
Gal/min
Percent solids
41
Bottom
ash to landfill
13,730
12,360
1,370
90
42
Fly ash
to landfill
66,270
49,700
16,570
75
1
2
)
'4
5
h
7
8
9
10
£
ll
1
|
i
1
11
I
!
!
f
i
69
-------
TABLE 12. EQUIPMENT LIST, DESCRIPTION, AND MATERIAL COST
BASE CASE 3 - HOLDING PONDS AND LANDFILL FOR NONHARDENING ASH
Material cost»
delivered,
Item (number); description 1982 k$
Area—1 Fly Ash Collection and Transfer
1. Economizer ash hoppers (4): Inverted pyramid-type hopper, 27
15 ft long x 15 ft wide x 16 ft deep, thermally isolated
design, constructed of 1/2-in. carbon steel plate
2. Air heater ash hoppers (4): Inverted pyramid-type 21
hopper, 15 ft long x 7 ft wide x 16 ft deep, constructed
of 1/2-in. carbon steel plate, insulated
3. ESP ash hoppers (32): Inverted pyramid-type hopper, 373
18 ft long x 12 ft wide x 16 ft deep, constructed of 1/2-
in. carbon steel plate, heat traced and insulated
4. Package-unit fly ash collecting and conveying system 228
comprising (1):
a. Vacuum pneumatic conveying lines for economizer air
heater ash and ESP ash (2): Pipelines and pipe
fittings for vacuum pneumatic conveyance of fly ash,
25 ton/hr conveying capacity with 600-ft equivalent
length system, 6-in. I.D. branch lines and 8-in. I.D.
main lines, nickel-chromium cast iron pipe with Ni-
Hard® or equivalent pipe fittings
b. Fly ash and air inlet valves (40): Self-feeding
materials handling valve, electrically actuated, air
operated, 12-in. I.D. ash inlet, 6-in. I.D. ash out-
let, cast iron body, stainless steel slide gate; each
assembly includes two spring-loaded, air-inlet check
valves with cast iron bodies
c. Line segregating valves (10): Segregating slide
valve, electrically actuated, air operated for on-
off control of each branch conveying line, 6-in. I.D.
port, cast iron body, stainless steel slide gate
d. Vacuum breaker valves (2): Vacuum breaker valve for
control of vacuum in main conveying line to
hydraulic exhauster, 8-in. I.D. port, cast iron body
(continued)
70
-------
TABLE 12 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
e. Hydraulic exhausters for vacuum pneumatic conveying
system (2): Vacuum producing hydraulic exhauster
with 8-in. I.D. air-ash inlet, 8-in. I.D. water
connection, and 10-in. I.D. discharge, cast iron body
with 250 psi water ejector head, chromium-iron alloy
air-ash inlet liner, stainless steel water nozzle
tips, ceramic-lined venturi throat; vertical
installation, tapped for vacuum and pressure gauges
f. System control unit (2): Automatic sequence control
unit to control the programmed operation of
materials handling valves, line segregating valves,
and water to hydraulic exhauster; includes gauges
for manual reading and override switches for manual
operation
5. Water supply pumps for hydraulic exhausters (4): Centri- 57
fugal pump, 600 gpm, 420-ft head, carbon steel body and
impeller; 110 hp (costed 80% in Area 1 and 20% in Area 2)
Total. Area 1 Zfi6_
Area 2—Fly Ash Conveyance to Disposal Site
1. Water supply pumps for fly ash conveyance (4): Same 14
pumps as in Area 1, Item 5 (costed 20% in Area 2 and 80%
in Area 1)
2. Air separator (1): Baffle-type cylindrical air 25
separator tank with cone bottom, dual 8-in. I.D. inlets
and single 12-in. I.D. slurry outlet, 8-ft I.D. carbon steel
shell with 30-mm basalt lining
3. Quarter-mile slurry pipeline to pond (1+1 spare): (92)a
Pipeline comprising 33 40-ft-long sections of flanged
steel pipe, 12-in. I.D., schedule 80 carbon steel and six
elbows or bends, 12-in. I.D., schedule 80 I.D. hardened
steel
4. Front-end loaders for loading trucks at fly ash holding 334
ponds (2): 977L Caterpillar or equivalent, track-type
front-end bucket loader, 3-yd3 bucket, 10-ft lift, 190-hp
diesel engine
(continued)
71
-------
TABLE 12 (continued)
Material costs
delivered,
Item (number)! description 1982 k$
5. Trucks for hauling ash from holding ponds to landfill 221
(2+1 spare): Tandem-axle 4 rear-wheel-drive dump truck
with ash-haul body, 20-yd3 capacity, 44,000-lb
suspension, 6 forward-speed manual transmission, 237-hp
diesel engine (costed 80% in Area 2 and 20% in Area 6)
6. Service truck for fuel, lubricants, and field service 20
(1): Service truck with 500-gal cargo tank for diesel
fuel and cargo space for lubricants and other field
service items (costed 80% in Area 2 and 20% in Area 6)
Total. Area 2 604
Area 3—Fly Ash Disposal Site
1. Fly ash holding pond with 5-yr capacity (1): Fly ash (2,534)a
holding pond, 1,461 ft square, with earthen perimeter
dike and 1-ft-thick clay liner; holding pond subdivided
by 1,461-ft-long divider dike into 15-ft-deep settling
pond with 1,020-ft-long median dike and into 100-ft-wide
x 5-ft-deep dewatering basin with 100-ft-long median
dike across middle; all interior dikes of bottom ash;
all dikes graded on top for 24-ft-wide service roads;
topsoil storage of 3.8 acres contiguous with topsoil
storage for adjacent bottom-ash pond; holding-pond
periphery monitored by three monitoring wells; holding
pond enclosed by 6-ft-high security fence which
surrounds entire pond disposal site
2. Common landfill for 25-yr capacity (1): Common landfill (1,491)3
for fly ash and bottom ash, 1,841-ft square with 1-ft-
thick clay liner, volume of 3,512,000 yd3, constructed
in one 20-ft lift with edge sloped upward at 1-vertical
to 2-horizontal (27°), edges and top covered as filled
with 1/2-ft-thick layer of clay and 1-1/2-ft-thick
layer of topsoil, 20 ft finished height at edge with
top sloped upward to center of landfill at 1-vertical
to 29-horizontal (2o), landfill surrounded by runoff and
leachate collection ditch 24 ft wide x 2.5 ft deep with
1-ft-thick clay liner; ditch drains to 257-ft-square
(continued)
72
-------
TABLE 12 (continued)
Material cost,
delivered,
Item (number); description 1992 k$
catchment basin with 1-ft-thick clay liner; site
includes 257-ft-square topsoil storage area, office
trailer with sanitary facilities, equipment storage
area, 24-ft-wide access roads, onsite water supply well
and three peripheral monitoring wells; overall landfill
disposal site of 110 acres is surrounded by 6-ft-high
security fence (costed 80% in Area 3 and 20% in Area 7)
3. Dozer for moving ash and earth at landfill (2): D4E 118
Caterpillar or equivalent, track-type with 10-ft-long U-
shaped blade, 75-hp diesel engine (costed 80% in Area 3
and 20% in Area 7)
4. Compactor for ash at landfill (1): Vibratory sheepsfoot 70
compactor, self-propelled, Raygo 420 C or equivalent
(costed 80% in Area 3 and 20% in Area 7)
5. Tank truck for dust control at landfill (1): Tandem-axle 33
4 rear-wheel-drive tank truck with spray-nozzle boom
attachment and pumping system, 2,000-gal fiberglass
tank, 130-hp diesel engine (costed 80% in Area 3 and 20%
in Area 7)
6. Front-end loader for stripping and restoring topsoil (1): 93
Caterpillar 950 or equivalent front-end bucket loader,
3-yd3 bucket, 130-hp diesel engine (costed 80% in Area 3
and 20% in Area 7)
7. Service truck for fuel, lubricants, and field service 20
(1): Service truck with 500-gal cargo tank for diesel
fuel and cargo space for lubricants and other field
service items (costed 80% in Area 3 and 20% in Area 7) _
Total. Area 3 _^-r
Area 4—Fly Ash Water Treatment and Recycle of Water
(Costed 80% in Area 4 and 20% in Area 8)
1. Sulfuric acid storage tank for pH control of water (2):
Cylindrical steel tank 5 ft 7 in. diameter x 5 ft 7 in.
high, 1,000 gal, flat bottom and closed flat top, carbon
steel
(continued)
73
-------
TABLE 12 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
2. Metering pump for sulfuric acid (2): Positive displace- 4
ment metering pump, 0.01 to 1 gpm, 0 psig with flow rate
controlled by a pH controller, Carpenter 20® alloy or
similar corrosion resistance to 93% sulfuric acid; 0.25
hp
3. Agitator for mixing of treated water (2): Agitator with 6
24-in.-diameter nickel-chromium blade; 5 hp
4. Pump for solids slurry from water treatment (2): Centri- 2
fugal pump, 5 gpm, 20 psig, carbon steel body and
impeller, 0.25 hp
5. Automatic samplers for water to discharge (2): Automatic 8
sampler with sample size controlled by flow rate, refrig-
erated storage of composite sample; all-weather housing
Total. Area 4 24
Area 5--Bottom Ash Collection and Transfer
1. Water supply pumps for bottom ash hopper and jet pumps 18
(2+1 spare): Centrifugal pump, 600 gpm, 250-ft head,
carbon steel body and impeller, 75 hp (costed 34% in
Area 5 and 66% in Area 6)
2. Bottom ash hopper assembly (1): Double-V hopper with 352
3,320-ft3 capacity for 12-hr ash containment, supported
independently of furnace-boiler and mated to furnace
through a water seal trough spanning the furnace seal
plate, hopper body of 3/8-in.-thick carbon steel plate,
hopper lined with monolithic refractory 9~in. thick in
upper section and 6-in. thick in lower section, stain-
less steel seal trough and overflow weirs, assembly
includes poke doors, lighted observation windows, access
doors and hydraulically operated ash exit doors; each V-
section of hopper includes two hopper-type, double-roll
grinders with cast iron body and 10-in.-diameter x 2-ft-
long manganese steel rolls; 60 hp
Total. Area 5 370
(continued)
74
-------
TABLE 12 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
Area 6—Bottom Ash Conveyance to Disposal Site
1. Water supply pumps for bottom ash jet pumps (2 + 36
1 spare): Same pumps as in Area 5, Item 1 (costed 66%
in Area 6 and 34% in Area 5)
2. Jet pumps for bottom ash conveyance (2+2 spares): Jet 49
ejector slurry pump, feed water capacity of 400 gpm at
250-ft head, outlet slurry capacity of 625 gpm at 120-ft
head, Ni-Hard nozzles and throat
3. Shutoff and crossover valves (10): Air-operated gate 23
valve, 8-in. I.D. port, Ni-Hard
4. Ouarter-mile slurry pipeline to holding pond, normal use (93)a
(1): Pipeline comprising 73 18-ft-long sections of
flanged, basalt-lined steel pipe, 8-in. I.D. and 6 basalt-
lined elbows or bends, 8-in. I.D.
5. Spare slurry pipeline to holding pond (1): Pipeline (23)a
comprising 33 40-ft-long sections of flanged steel pipe,
8-in. I.D., schedule 80 carbon steel and 6 hardened steel
elbows or bends, 8-in. I.D.
6. Front-end loader for loading trucks at bottom ash holding 167
pond (1): Caterpillar 977L or equivalent, track-type
front-end bucket loader, 3-yd3 bucket, 10-ft lift, 190-
hp diesel engine
7. Trucks for hauling ash from holding pond to landfill (2 + 53
1 spare): Same trucks as in Area 2, Item 5 (costed 20%
in Area 6 and 80% in Area 2)
8. Service truck for fuel, lubricants, and field service (1): 5
Same truck as in Area 2, Item 6 (costed 20% in Area 6
and 80% in Area 2)
Total. Area 6 333
Area 7—Bottom Ash Disposal Site
1. Bottom ash holding pond for 5-yr capacity (1): Bottom (608)a
ash holding pond, 815 ft square x 11.8 ft deep, with
(continued)
75
-------
TABLE 12 (continued)
Material cost.
delivered,
Item (number); description 1982 k$
earthen perimeter dikes and 1-ft-thick clay liner; 536-
ft-long bottom ash divider dike; all dikes graded on top
for 24-ft-wide service roads, pond area of 15.2 acres,
pond volume of 233,000 yd3, topsoil storage of 0.9 acre
contiguous with topsoil storage for adjacent fly ash
pond, pond periphery monitored by two monitoring wells,
bottom ash pond enclosed by 6-ft-high security fence
which surrounds entire pond disposal site
2. Common landfill for 25-yr capacity (1): Same landfill as (372)a
in Area 3, Item 2 (costed 20% in Area 7 and 80% in Area 3)
3. Dozer for moving ash and earth at landfill (1): Same 30
dozer as in Area 3, Item 3 (costed 20% in Area 7 and 80%
in Area 3)
4. Compactor for ash at landfill (1): Same compactor as in 18
Area 3, Item 4 (costed 20% in Area 7 and 80% in Area 3)
5. Tank truck for dust control at landfill (1): Same truck 8
as in Area 3, Item 5 (costed 20% in Area 7 and 80% in
Area 3)
6. Front-end loader for stripping and replacing topsoil (1): 23
Same loader as in Area 3, Item 6 (costed 20% in Area 7
and 80% in Area 3)
7. Service truck for fuel, lubricants, and field service (1): 5
Same truck as in Area 3, Item 7 (costed 80% in Area 7
and 20% in Area 3)
Total. Area 7 84
Area 8—Bottom Ash Water Treatment and Recycle of Water
(Costed 20% in Area 8 and 80% in Area 4)
1. Sulfuric acid storage tank for pH control of water (2): 1
Same tanks as in Area 4, Item 1
2. Metering pump for sulfuric acid (2)5 Same pumps as in 1
Area 4, Item 2
(continued)
76
-------
TABLE 12 (continued)
Material cost,
delivered,
Item (number)! description 1982 k$
3. Agitator for mixing of treated water (2): Same agitators 1.5
as in Area 4, Item 3
4. Pump for solids slurry from water treatment (2): Same 0.5
pumps as in Area 4, Item 4
5. Automatic samplers for water to discharge (2): Same 2
samplers as in Area 4, Item 5
Total. Area 8 6.
Total, Base Case 3 2,461
a. Costs shown in parentheses are informational and are not included in
totals for equipment material cost.
.t
77
-------
because of the lower dynamic head of the bottom ash system in this system.
With the exception of the jet pump, all equipment, rates, and procedures are
identical to base case 1.
Ash Ponds
The same pond and pond site design is used, as in base case 1, but both
ponds are designed for a five-year capacity. The pond site is situated one-
fourth mile from the power plant and it occupies 102 acres, including working
and storage areas. The flow rates to the ponds are identical to those of base
case 1 and the treatment of the pond effluents is similar to that of base
case 1.
The fly ash pond occupies a contained area of 55 acres and has a capacity
of 0.9 million yd-* of settled ash 15 feet deep when full. One side of the
fly ash pond consists of two dewatering basins. These basins are separated
from the main pond by a permeable dike constructed of bottom ash and the
bottoms are elevated above the main pond bottom. Settled fly ash from the
main pond is removed with a floating hydraulic dredge and pumped alternately
into one of the two dewatering basins where it settles to 75% solids as the
water drains back into the main pond.
The bottom ash pond occupies a contained area of 16 acres and has a
capacity of 0.2 million yd* when filled to a depth of 12 feet. No
dewatering basins are needed for bottom ash because it settles readily and
supports mobile equipment.
Ash Removal and Transportation
Fly ash is removed from the dewatering basins and bottom ash from the
bottom ash pond using track-type front loaders, loaded on trucks, and hauled
three-fourths of a mile to the disposal site. A single landfill is used for
both ashes. Two rear-dump, 44,000 Ib, 20 yd^, ash-haul-body trucks are
used. The mobile equipment is sized for 1.5 times the ash production rate.
The pond, trucking, and landfill disposal equipment is operated two shifts/day
during the power plant operating year of 5500 hours. At the end of 25 years
of operation ash removal operations are halted. The ponds are then allowed to
fill to capacity during the final 5 years of power plant operation.
Landfill
The common landfill site occupies 110 acres, including topsoil storage,
runoff control, and working areas. The filled area occupies 78 acres. The
landfill is designed for a 25-year capacity of 3.5 million yd^ using a 90
lb/ft^ dry bulk density and 17% moisture for both types of ash. The design
and operation are described in the premises. Sections of the landfill are
prepared, filled, and covered progressively to minimize the disturbed area.
Topsoil stripped from each new section is used to cover the previously filled
section. The stripped section is lined with one foot of clay and covered with
two feet of bottom ash which acts as a porous drainage base. The clay and ash
base is designed to drain to a catchment basin about two acres in size, which
also receives runoff from the perimeter ditches. The collected water, is
augmented by well water when needed, is returned to the landfill and used for
compaction moisture and revegetation irrigation.
78
-------
The fly ash and bottom ash are placed in successive, compacted lifts to a
center height of 51 feet. The ash
revegetated. The completed fill has
and a top sloping slightly upward
is then covered with clay and topsoil and
side slopes of 1 vertical to 2 horizontal
to the center. Provision for monitoring
wells, catchment basin water trea:ment, offices and equipment facilities,
roads, and topsoil storage are provided. Two track-type dozers, a front-end
loader, and a self-propelled compactor are used to prepare and maintain the
site. A water truck is also provided for dust control.
BASE CASE 4 - DIRECT LANDFILLING OF
Base case 4 represents a common
collected dry and landfilled and
NONHARDENING ASH
sluiced from the bottom ash hoppers and also landfilled. This method
minimizes water use, reduces the .imount of recycled water, and eliminates
discharge of transportation water.
vacuum system. It is removed fron
settling bins and also trucked to
and bottom ash are segregated
utilization potential.
disposal practice in which the fly ash is
the bottom ash is dewatered after being
Dry collection of fly ash also facilitates
handling and improves its utilization potential. The flow diagram, disposal
site plan, and plot plan for base case 4 are shown in Figures 16, 17, and 18.
The material balance is shown in Table 13 and the equipment list is shown in
Table 14.
Fly ash is collected in silos using a mechanically induced pneumatic
the silos, moistened and trucked to the
landfill. Bottom ash sluiced fron the bottom ash hoppers is dewatered in
:he landfill. At the disposal site fly as
separate landfills to improve their
Fly Ash Collection
n
a: id
in
The economizer, air heater,
the vacuum pneumatic systems used
and air heater ash is collected s
addition, vacuum is applied by two
removed from the conveying system
and secondary centrifugal separators
system is designed for a 19 in. H
an ash-to-air ratio of about 30
provided. The design capacity
operating schedule.
ESP ash conveying system is similar to
the previous base cases. The economizer
eparately from the ESP ash, however. In
lobe-type mechanical exhausters. Ash is
upstream from the vacuum pumps in primary
followed by a fabric filter unit. The
vacuum and a 1,500 sft-Vmin air flow at
to 1. Automatic cycling controls are
s 53 tons/day, permitting a 12 hr/day
The primary collectors consist
of the ash in the conveying systems
increase the total removal to 97%.
type fabric filters with a 1.5
ash falls into cylindrical ste<;l
capacities. The silos are elevatec
and are equipped with fluidizing s;
and air heater ash silo is 16 feet
silo is 38 feet in diameter and 50
of centrifugal separators that remove 83%
The secondary centrifugal collectors
The remaining ash is removed in shaker-
aft3/min/ft2 filter area. The collected
storage silos with 64-hour storage
for direct loading of trucks or rail cars
rstems and filtered vents. The economizer
in diameter and 18 feet high. The ESP ash
:eet high.
79
-------
CO
o
ASH
IN COAL
ECONOMIZER 4
AIR HEATER
ASH STORAGE
MOIST BOTTOM
ASH TO LANDFILL
I MILE
RECYCLE WATER
TO LANDFILL
Figure 16. Flow diagram. Base case 4, direct landfill of nonhardening ash.
-------
POWER PLANT TO LANDFILL, I MILE
ACCESS
ROAD
yf .._1
1,159 FEET
GROUNDWATER FLOW
BOTTOM ASH
LANDFILL
847,000 YD3 VOLUME
-X X-
MONITORING WELL
4
* *-* *-
34-FOOT RUNOFF CATCHMENT DITCH
MONITORING WELL #Z
FLY ASH
LANDFILL
1,957 FEET
MONITORING WELL
1,01 1 FEET
3,367,000 YD3 VOLUME
798 FEET
284FEET1
o |
J.EQUIPMENT
STORAGE OFFICE
AREA TRAILER
REAGENTS
h-
WELL
WATER
AND
STORAGE
RECYCLE TO LANDFILL
RUNOFF
CATCHMENT
BASIN
®«— MONITORING WELL #4
1,809 FEET
TO DISCHARGE
3, 140 FEET
6-FOOT SECURITY FENCE
/ _J
- '
GROUNDWATER
FLOW TO RIVER
TOTAL LAND AREA,I 42 ACRES
Figure 17. Disposal site. Base case 4, direct landfill of nonhardening ash.
-------
COAL STORAGE
00
| W *=>°
ROAD
MOIST FLY ASH AND BOTTOM ASH
TRUCKS TO LANDFILLS , I MLE
ROAD
>
OL
Figure 18. Plot plan. Base case 4, direct landfill of nonhardening ash.
-------
TABLE 13.
BASE CASE 4 - DIRECT
MATERIAL BALANCE
,ANDFILL OF NONHARDENING ASH
Stream No.
Description
2
J
4
5
h
7
8
9
10
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ft-Vmin, 60°F
gal/min
Percent solids
Stream No.
2
)
4
5
6
7
8
9
10
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ftj/min, 60oF
gal/min
Percent solids
Steam No.
1
2
J
4
^.
f)
7
8
9
10
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ftj/min, 60°F
gal/min
Percent solids
Stream No.
2
1
4
5
6
7
H
9
10
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ft-Vmin, 60°F
gal/min
Percent solids
]
Coal ash
to furnace
62,400
62,400
6
Ash to
air heater
48,360
4s, jt>u
11
ESP ash in
pneumatic systen
47,900
46,510
1,310
16
Economizer -air
heater ash
from secondary
collector
446
446
e
As
fro
Ai
Ecoi
b.
2
Ash to
onomizer
49,920
49,920
7
collected
air heater
1,560
i ,:>bu
12
h to FGD
system
285
285
17
omizer-air
leater
sh from
g filter
94
94
3
Ash collected
from economizer
1,560
1,560
8
Economizer -air
heater ash
in pneumatic
system
3,220
3,120
100
13
Ash in FGD
1 waste
143
143
18
Air from
EC onomizer- air
heater ash
bag filter
100
100
27
^
Air intake to
economizer ash
pneumatic system
100
100
22
i
Economizer ash
in pneumatic
system
1,660
1,560
100 i
9
Ash to ESP
46,800
46,800
14
142
142
19
Economizer -
air heater
ash from storage
3,120
3,120
10
Air intake to
ESP ash
pneumatic system
1,390
1,390
303
15
Economizer- air
heater ash from
pr y
2,580
2,580
20
Water
to economizer -
air heater
ash moisturizer
347
0.4
347
0. 7
(c
ntinued)
83
-------
TABLE 13 (continued)
Stream No.
J
2
i
4
•>
d
7
«
9
JO
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ftj/min, 60°F
gal/min
Percent solids
21
Moisturized
economizer -air
heater ash
to landfill
3,468
3,121
347
90
22
ESP ash
from primary
collector
38,470
38 , 4 70
23
ESP ash
from secondary
collector
6,650
6,650
24
ESP ash from
bag filter
1,390
1,390
25 |
Air from |
fly ash
bag filter
1,390
1,390
303
1
I
1
4
5
f>
/
8
9
10
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ft3/min, 60°F
Eal/min
Percent solids
26
Air from
mechanical
1,490
1,490
325
27
ESP ash
0
28
ESP ash
46,510
46,510
29
Water to
ESP ash
5,160
5
5,160
10
30
Moisturized
ESP ash to
51,670
46,510
5,160
90
Stream No.
1
;
J
4
^
6
7
K
9
10
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
ft^/min, 60°F
gal/min
Percent solids
31
Recycle
water to
to landfill
4,710
50
4,660
9
32
Fly ash
landfill
59,800
49,630
10,170
83
33
Rainfall
to fly
ash landfill
90,840
90,840
182
34
Water
from fly
ash landfill
to treatment
90,890
50
90,840
182
35
Water to bottom
ash hopper
50,950
45
50.900
102
Stream No.
1
i
1
4
•>
h
/
8
9
10
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
ftj/min, 60°F
gal/min
Percent solids
36
Slurry
to bottom
ash pump
75,190
12,540
62,650
138
16.7
37
Underflow from
settling tank
6,050
540
5,510
12
9
38
Water from
dewatering bin
to settl irg tank
67,370
600
66,770
134
39
Overflow
water from
settling tank
63.940
70
63,870
128
40
Underflow
from water
reservoir
2, WO
10
2,610
5
(continued)
84
-------
TABLE 13
(continued)
Description
1
2
\
5
b
7
K
9
in
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ft3/min, 60°F
gal/min
Description
1
•>
\
4
5
h
7
8
<)
1°.
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
H2S04
ft^/min, 60°F
Bal/min
Description
1
7
i
4
5
6
7
H
9
10
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
ft^/min, 60°F
gal/min
Percent solids
i
•i
i
4
5
6
7
8
9
10
41
Bottom ash
utilization
0
46
Combined
runoff water
from landfill
122,750
55
122,590
245
51
Makeup water
6,840
6,840
14
Dew
bott
to 1.
13
12
1
Reage
Ian
W
to
ash
1
1
42
itered
im ash
jndfill
870
480
390
90
+1
its for
Ifill
60
60
0.06
52
ater
)ottom
slurry
1,760
10
1,750
24
43
Bottom
ash landfill
13,870
12,480
1,390
90
48
Treated
landfill water
118,100
10
118,090
236
44
Rainfall to
bottom
ash landfill
31.85Q
31.850
64
49
Reagents for
water reservoir
60
60
0.06
4S j
Runoff water \
from bottom
ash landfill
to treatment
31,860
5
31,850
64
5fl
Overflow from
water reservoir
68,220
60
68,160
136
85
-------
TABLE 14. EQUIPMENT LIST, DESCRIPTION, AND MATERIAL COST
BASE CASE 4 - DIRECT LANDFILL OF NONHARDENING ASH
Material cost,
delivered,
Item (number); description 1982 k$
Area 1—Fly Ash Collection and Transfer
1. Economizer ash hoppers (4): Inverted pyramid-type 27
hopper, 15 ft long x 15 ft wide x 16 ft deep, thermally
isolated design, constructed of 1/2-in. carbon steel
plate
2. Air heater ash hoppers (4): Inverted pyramid-type 21
hopper, 15 ft long x 7 ft wide x 16 ft deep, constructed
of 1/2-in. carbon steel plate, insulated
3. ESP ash hoppers (32): Inverted pyramid-type hopper, 373
18 ft long x 12 ft wide x 16 ft deep, constructed of 1/2-
in. carbon steel plate, heat traced and insulated
4. Economizer-air heater ash collection and transfer system 96
comprising (1):
a. Vacuum pneumatic conveying lines for economizer-air
heater ash (1): Pipelines and pipe fittings for
vacuum pneumatic conveyance of ash, 5 ton/hr
conveying capacity with 600-ft equivalent length
system, 4-in. I.D. branch lines and 6-in. I.D. main
lines, nickel-chromium cast iron pipe with Ni-Hard®
or equivalent pipe fittings
b. Ash and air inlet valves (8): Self-feeding
materials handling valve, electrically actuated,
air operated, 12-in. I.D. ash inlet, 4-in. I.D. ash
outlet, cast iron body, stainless steel slide gate;
each assembly includes two spring-loaded, air-inlet
check valves with cast iron bodies
c. Line segregating valves (5): Segregating slide
valve, electrically actuated, air operated for on-
off control of each branch conveying line, 4-in.
I.D. port, cast iron body, stainless steel slide
gate
d. Vacuum breaker valves (1); Vacuum breaker valve for
control of vacuum in air line from bag filter, 6-
in. I.D. port, cast iron body
(continued)
86
-------
TABLE
4 (continued)
Item (number); description
Material cost,
delivered,
1982 k$
System control unit (1):
unit to control the programWed
rials handling valves, lin
mechanical exhauster; incl
reading and override switc
5• Economizer~air heater ash sepa:
utomatic sequence control
ted operation of mate-
segregating valves, and
des gauges for manual
es for manual operation
ation system
comprising (1):
a. Primary air-ash separator
separator with tangential
type vortex finding sleeve
outlet; two-gate, three-ch
lock provision cycled for
operation; 3.5 ft diameter
capacity; carbon steel she
velocity compartment
1): Primary centrifugal
ir-ash inlet, cyclone-
and top vertical air
mber ash removal and air
ontinuous vacuum
x 12 ft high, 4.1 ton/hr
1, Ni-Hard liners in high-
Secondary air-ash separate:
c.
centrifugal separator simi
ton/hr capacity
Air-ash bag filter (1): B.
service at 150°F, 19-in. Hj
area, cycled bag shaker an<
storage bin, 0.15 ton/hr a
6. ESP ash collection and transfei
(1): Secondary
ar to primary unit, 0.75
g filter for air-ash
vacuum, 200-ft2 cloth
air-lock delivery to
pacity
system comprising (1):
a. Vacuum pneumatic conveying
.ines for ESP ash (1):
Pipelines and pipe fitting
conveyance of ash, 48
600-ft equivalent length sj
lines and 10-in. I.D. main
cast iron pipe with Ni-Har
fittings
Ash and air inlet valves (:
materials handling valve, «
operated, 12-in. I.D. ash i
outlet, cast iron body, sts
each assembly includes two
check valves with cast iroi
for vacuum pneumatic
conveying capacity with
stem, 6-in. I.D. branch
lines, nickel-chromium
or equivalent pipe
2): Self-feeding
lectrically actuated, air
nlet, 6-in. I.D. ash
inless steel slide gate;
spring-loaded, air-inlet
bodies
(continued)
87
26
160
-------
TABLE 14 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
c. Line segregating valves (5): Segregating slide
valve, electrically actuated, air operated for on-
off control of each branch conveying line, 6-in.
I.D. port, cast iron body, stainless steel slide
gate
d. Vacuum breaker valve (1): Vacuum breaker valve for
control of vacuum in air line from bag filter, 10-
in. I.D. port, cast iron body
e. System control unit (1): Automatic sequence control
unit to control the programmed operation of
materials handling valves, line segregating valves,
and mechanical exhauster; includes gauges for manual
reading and override switches for manual operation
7. ESP ash separation system comprising (1): 52
a. Primary air-ash separator (1): Primary centrifugal
separator with tangential air-ash inlet, cyclone-
type vortex finding sleeve, and top vertical outlet;
two-gate, three-chamber ash removal and air-lock
provision cycled for continuous vacuum operation; 5
ft diameter x 17 ft high; 40 ton/hr capacity, carbon
steel shell, Ni-Hard in high-velocity compartment
b. Secondary air-ash separator (1): Secondary
centrifugal separator similar to primary unit except
3.5 ft diameter x 12 ft high for 6.9 ton/hr capacity
c. Air-ash bag filter (1): Bag filter for air-ash
service at 15QOF, 19-in. Hg vacuum, I,200-ft2 cloth
area, cycled bag shaker and air-lock delivery to
storage bin, 1.4 ton/hr capacity
8. Mechanical exhausters for economizer-a;Lr heater and ESP 79
ash collection and transfer systems (2 +• 1 spare):
Mechanical exhauster, two-impeller, straight-lobe type,
1,000 aft3/min air at 19-in. Hg vacuum and 150°F, 8-
in. I.D. inlet, connected to common vacuum plenum,
equipped with silencer and inline prefilter, 100 hp
Total. Area 1 834
(continued)
88
-------
TABLE 14 (continued)
Item (number); description
Material cost,
delivered,
1982 k$
Area 2—Flv Ash Conveyance to Disposal Site
1. Economizer-air heater ash storage bin (1): Economizer-
it diameter x 18 ft high,
211
air heater ash storage bin, 16
3,600 ft volume, with bin-air
filter, elevated construction
clearance, carbon steel plate,
fluidizing system and vent
for 22-ft railroad
hp
ESP ash storage bin (1): ESP
diameter x 50 ft high, 57,000 f
fluidizing system and vent filt
for 22-ft railroad clearance,
ash
storage bin 38 ft
t volume, with bin-air
r, elevated construction
carbon steel plate, 10 hp
468
3. Moisturizers for economizer-air
heater and ESP ash from
50
storage bins (2): Continuous
moisturizing to 90% solids, inc
to control flow from storage
conveyor, 30-in.-diameter drum,
uploader and mixer for
udes rotary star feeder
double-flight screw
50 ton/hr capacity, 5 hp
bin
4. Trucks for hauling economizer-a
r heater ash and ESP ash
211
from storage bins to fly ash laadfill (2+1 spare):
capacity
Tandem-axle 4 rear-wheel-drive
body, air heater ash 20-yd3
ash from suspension, 6 forward-
manual transmission, 237-hp fly
engine (costed 80% in Area 2 anji
pump truck with ash haul
44,000-lb and ESP
peed storage bins to
ash landfill diesel
20% in Area 6)
Total. Area 2
940
Area 3—Flv Ash Disposal Site
1. Fly ash landfill (1): Fly ash
with 1-ft-thick clay liner, voljame
constructed in one 20-ft lift w:
1-vertical to 2-horizontal (27
-------
TABLE 14 (continued)
Material cost,
delivered,
Item (number)i description 1982 k$
storage area, office trailer with sanitary facilities,
equipment storage area, 24-ft-wide access roads, on-site
water supply well and three peripheral monitoring wells;
landfill periphery is enclosed by 6-ft-high security
fence
2. Dozers for moving ash and earth at landfill (2): D4E 118
Caterpillar or equivalent track-type with 10-ft-long U-
shaped blade, 75-hp diesel engine (costed 80% in Area 3
and 20% in Area 7)
3. Compactor for ash at landfill (1): Vibratory sheepsfoot 70
compactor, self propelled, Raygo 420 C or equivalent
(costed 80% in Area 3 and 20% in Area 7)
4. Tank truck for dust control at landfill (1): Tandem 33
axle, 4 rear-wheel-drive tank truck with spray nozzle
boom attachment, and pumping system, 2,000-gal
fiberglass tank, 130-hp diesel engine (costed 80% in
Area 3 and 20% in Area 7)
5. Front-end loader for stripping and restoring 93
topsoil (1): 950 Caterpillar or equivalent, wheeled,
with 3-yd bucket, 130-hp diesel engine (costed 80% in
Area 3 and 20% in Area 7)
6. Service truck for fuel, lubricants, and field 20
service (1): Service truck with 500-gal cargo tank for
diesel fuel and cargo space for lubricants and other
field service items (costed 80% in Area 3 and 20% in
Area 7)
Total. Area 3
Area 4—Fly Ash Water Treatment and Recycle of Water
(Costed 80% in Area 4 and 20% in Area 8)
1. Sulfuric acid storage tank for pH control of water to
discharge (1): Cylindrical steel tank, 5 ft 7 in.
diameter x 5 ft 7 in. high, 1,000 gal, flat bottom and
closed flat top, carbon steel; all-weather housing
(continued)
90
-------
TABLE 14 (continued)
" Material cost,
delivered,
Item (number); description 1982 k$
2. Metering pump for sulfuric acid (1+1 spare): Positive 2
displacement metering pump, 0.01 to 1 gpm, 0 psig, with
flow rate controlled by a pH controller, Carpenter 20®
alloy or similar corrosion resistance to 93% sulfuric
acid; 0.25-hp
3. Agitator for mixing of treated water (1): Agitator with 3
24-in.-diameter nickel-chromium blade; 5 hp
4. Pump for solids slurry from water treatment (1+1 1
spare): Centrifugal pump, 10 gpm, 20 psig, carbon steel
body and impeller, 0.5 hp
5. Automatic sampler for water to discharge (1): Automatic 4
sampler with sampler size controlled by flow rate,
refrigerated storage of composite sample; all-weather
housing
Total. Area 4 L2
Area 5—Bottom Ash Collection and Transfer
1. Water supply pumps for bottom ash hopper and slurry (1 + 34
1 spare): Centrifugal pump, 550 gpm, 250-ft head,
carbon steel body and impeller, 60 hp
2. Bottom ash hopper assembly (1): Double-V hopper with 352
3,320-ft3 capacity for 12-hr ash containment, supported
independently of furnace-boiler and mated to furnace
through a water seal trough spanning the furnace seal
plate, hopper body of 3/8-in.-thick carbon steel plate,
hopper lined with monolithic refractory 9 in. thick in
upper section and 6 in. thick in lower section,
stainless steel seal trough and overflow weirs, assembly
includes poke doors, lighted observation windows, access
doors, and hydraulically operated ash exit doors; each V-
section of hopper includes two hopper-type, double-roll
grinders with cast iron body and 10-in.-diameter x 2-ft-
long manganese steel rolls; 60 hp
Total. Area 5 386
(continued)
91
-------
TABLE 14 (continued)
Material cost,
delivered,
Item (number): description 1982 k$
Area 6--Bottom Ash Conveyance to Disposal Site
1. Slurry pumps for pipeline conveyance (1+1 spare): 52
Centrifugal slurry pumps, 550 gpm, 150-ft head, Ni-Hard
liner and impeller, 50-hp motor
2. Shutoff and crossover valves (10): Air-operated gate 23
valve, 8-in. I.D. port, Ni-Hard
3. One-eighth mile basalt-lined slurry pipeline to (46)a
dewatering bins, normal use (1): Pipeline comprising 37
18-ft-long sections of flanged, basalt-lined steel pipe,
8-in. I.D. and 4 basalt-lined elbows or bends, 8-in.
I.D.
4. Spare slurry pipeline to dewatering bins (1): Pipeline (12)a
comprising 17 40-ft-long sections of flanged steel pipe,
8-in. I.D., schedule 80 carbon steel and 4 hardened elbows
or bends, 8-in. I.D.
5. Dewatering bins for bottom ash slurry (2): Conical- 430
bottom dewatering bin, 25-ft-diameter x 19-ft-high
cylindrical section, 19-ft-high cone, 11,100 ft3, stain-
less steel floating decanter and movable drain pipe, sta-
tionary decanters in conical section, erected for 22-ft
railroad clearance, carbon steel bin, stainless steel
decanter drum
6. Trucks for hauling moist bottom ash from dewatering bins 53
to bottom ash landfill (2+1 spare): Same trucks as in
Area 2, Item 4 (costed 20% in Area 6 and 80% in Area 2)
Total. Area 6 558
Area 7--Bottom Ash Disposal Site
1. Bottom ash landfill (1): Bottom ash landfill, 1,011 ft (487)a
square with 1-ft-thick clay liner, volume of 847,000
yd3, constructed in one 20-ft lift with edge sloped upward
at 1-vertical to 2-horizontal (27o), edges and top
covered as filled with 1/2-ft-thick layer of clay and 1-
1/2-ft-thick layer of topsoil, 20-ft finished height at
(continued)
92
-------
TABLE 14 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
edge with top sloped upward to center of landfill at 1-
vertical to 29-horizontal (2o), landfill surrounded by
runoff and leachate collection ditch 24 ft wide x 2.5 ft
deep with 1-ft-thick clay liner; ditch drains to common
284-ft-square catchment basin with 1-ft-thick clay
liner; site includes 363-ft-square common topsoil
storage area, office trailer with sanitary facilities,
equipment storage area, 24-ft-wide access roads, onsite
water supply well and 2 peripheral monitoring wells;
landfill periphery is enclosed by 6-ft-high security
fence
2. Dozers for moving ash and earth at landfill (2): Same 30
dozers as in Area 3, Item 2 (costed 20% in Area 7 and
in Area 3)
3. Compactor for ash at landfill (1): Same compactor as in 18
Area 3, Item 3 (costed 20% in Area 7 and 80% in Area 3)
4. Tank truck for dust control at landfill (1): Same 8
trucks as in Area 3,8 Item 4 (costed 20% in Area 7 and
in Area 3)
5. Front-end loader for stripping and restoring 23
topsoil (1): Same loader as in Area 3, Item 5 (costed
20% in Area 7 and 80% in Area 3)
6. Service truck for fuel, lubricants, and field 5
service (1): Same service truck as in Area 3, 5 Item 7
(costed 20% in Area 7 and 80% in Area 3)
Total. Area 7 84
Area 8--Bottom Ash Water Treatment and Recycle of Water
1. Settling tank for clarifying water (1): Settling tank, 73
50 ft diameter x 15 ft deep, 220,000 gal, carbon steel
2. Water reservoir for bottom ash dewatering system (1): 52
Water reservoir, 40 ft diameter x 16 ft deep, 150,000
gal, carbon steel
(continued)
93
-------
TABLE 14 (continued)
Material cost,
delivered*
Item (number) t description 1982 k$
3. Recycle pump for underflow solids from settling tank and 3
water reservoir (1): Centrifugal pump, 100 gpm, 100-ft
head, carbon steel body and impeller, 5 hp
4. Sulfuric acid storage tank for pH control of return 2
water from water reservoir (1): Cylindrical steel tank,
5 ft 7 in. diameter x 5 ft 7 in. high, 1,000 gal, flat
bottom and closed flat top, carbon steel; all-weather
housing
5. Metering pump for sulfuric acid to return water (1): 2
Positive displacement metering pump 0.01 to 1 gpm, 0
psig, Carpenter 20 alloy or similar corrosion resistance
to 93% sulfuric acidj 0.25-hp, flow rate controlled by a
pH controller
6. Sulfuric acid storage tank for pH control of water to 0.5
discharge (1): Same tank as in Area 4, Item 1 (costed
20% in Area 8 and 80% in Area 4)
7. Metering pump for sulfuric acid to discharge water (1 + 0.5
1 spare): Same pump as in Area 4, Item 2 (costed 20% in
Area 8 and 80% in Area 4)
8. Agitator for mixing of treated water (1): Same agitator 0.75
as in Area 4, Item 3 (costed 20% in Area 8 and 80% in
Area 4)
9. Pump for solids slurry from water treatment (1+1 0.25
spare): Same pump as in Area 4, Item 4 (costed 20% in
Area 8 and 80% in Area 4)
10. Automatic sampler for water to discharge (1): Same 1
sampler as in Area 4, Item 5 (costed 20% in Area 8 and
80% in Area 4)
Total. Area 8 135
Total, Base Case 4 3,283
Costs shown in parentheses are informational and are not included in
area or base case totals for equipment material costs.
94
-------
Ash is removed from the silos through moisturizers that blend water with
the ash to control dusting. Each moisturizer consists of an inclined rotating
drum containing a screw conveyor and water spray nozzles. Fly ash is fed from
the silos through a rotary feeder. It is blended with 10% water in the
moisturizer by the mixing action of the rotating drum and the screw conveyor,
which moves it upslope to the discharge. The moistened ash falls directly
from the moisturizer into a truck.
Bottom Ash Collection
Bottom ash is sluiced from the bottom ash hoppers in a system identical
to that of base case 1. Instead of being pumped to a pond, however, it is
pumped 660 feet to one of two dewatering bins. Because of the short distance
the ash content of the slurry is 16.7% instead of the 7.7% used in the
previous base cases.
The dewatering bins are conical-bottom steel vessels 25 feet in diameter
by 38 feet high with an 83,000 gallon (11,100 ft3) volume and a 10-hour
capacity. The bins are elevated for direct loading into trucks or rail cars.
The associated water recycling system consists of a 220,000 gallon settling
tank and a 150,000 gallon water reservoir. A sulfuric acid water treatment
system is also included.
At the beginning of the ash removal cycle the dewatering bin that is to
receive the ash is partially full of water. The ash is sluiced to the
dewatering bin using water from the bottom ash hopper and the reservoir tank
while overflow water from the dewatering bin flows through the settling tank
and back to the reservoir tank. Bottoms from the settling tank, which contain
fines and sludge, are pumped back to the dewatering bin. At the end of the
ash removal cycle the dewatering bin is drained to the settling tank and
overflowed to the reservoir tank. Ash is allowed to drain to a water content
of 10% and is dumped to trucks and at the same time the alternate dewatering
bin is being partially filled from the reservoir tank. Makeup water and
sulfuric acid for pH adjustment are added to the reservoir tank as necessary.
The ash slurry rate to the dewatering bin is 550 gal/min while the system is
operating and averages 138 gpm over a 24-hour period. After dewatering, each
dewatering bin has an ash capacity of about 40 hours of boiler operation.
Ash Transportation
Moistened fly ash from the moisturizers on the fly ash silos and bottom
ash from the dewatering bins are dumped directly into trucks and hauled to the
disposal site. Two 44,000 Ib, 20 yd^, ash-haul-body trucks are used for
total ash haulage and they are operated two shifts/day during the power plant
operating year.
Landfill
Fly ash and bottom ash are trucked to separate contiguous landfills on a
site one mile from the power plant. The landfill has a 30-year capacity. The
disposal site design is described in the premises. The design and operation
is similar to the base case 3 landfill except for the segregation of ash by
type. The disposal site occupies 142 acres, 75 acres of which is a fly ash
95
-------
landfill of 3.4 million yd^ and 24 acres of which is a bottom ash landfill
of 0.8 million yd^. Both landfills are stripped, prepared, filled, and
covered in successive sections using topsoil from each section stripped to
cover the previous section. A 1-foot clay liner, a 2-foot porous base of
bottom ash for the fly ash landfill, and a catchment basin identical in
function to base case 3 are provided.
The ash is built up in successive compacted layers to a center of 50 feet
for the fly ash landfill and 36 feet for the bottom ash landfill. The side
slope is 1 vertical to 2 horizontal and there is slight slope of the top
upward to the center. A compacted dry bulk density of 90 Ib/ft^ and a 17%
moisture content are used for the fly ash landfill while the bottom ash
landfill has 10% moisture. At the design height the ash is covered with 6
inches of clay and 18 inches of topsoil and revegetated.
Provisions for monitoring wells, catchment basin water treatment, offices
and equipment facilities, roads, and topsoil storage are also included. Two
dozers, a front-end loader, a compactor, and a watering truck are provided for
operation of the site.
BASE CASE 5 - DIRECT LANDFILLING OF SELF-HARDENING ASH
Base case 5 represents an increasingly common situation in which a high-
calcium coal is used. These coals are typically western coals characterized
by a lower sulfur and ash content and a lower heating value than typical
eastern coals, as well as a higher alkali and alkali earth metal content. The
use of the low-sulfur western coal described in the premises results in the
production of 24% less ash than that produced using the high-sulfur eastern
coal. It also results in an ash containing 10% calcium instead of the 2% with
the eastern coal. The self-hardening properties of such high-calcium fly
ashes can create disposal problems if the ash is wetted before final placement
and compaction at the disposal site. From some coals, the ash may harden
sufficiently to set up in bins, lines, and trucks and it may be difficult to
compact. The inherent increase in shear strength and impermeability of self-
hardening ash may also be lost if the reactions are allowed to start before
placement and compaction. Bottom ash, which is composed of larger, less-
reactive particles, does not normally present such problems.
The handling and disposal methods of base case 5 are designed to keep the
fly ash dry until immediately before it is placed in the landfill. The flow
diagram, disposal site plan, and plot plan are shown in Figures 19, 20, and
21. The material balance and equipment list are shown in Tables 15 and 16.
Economizer and air heater fly ash and ESP fly ash are collected
separately in storage bins using a pneumatic vacuum system powered by
mechanical exhausters. Bottom ash is sluiced to dewatering bins using
recycled water. The ashes are placed in separate landfills on the same
disposal site situated one mile from the power plant. The fly ash is
transported dry in covered dump trucks. It is blended with water by truck-
mounted moisturizers as it is dumped. The bottom ash is transported in
regular dump trucks. The landfill design and operation are the same as those
of base case 4.
96
-------
VD
ASH
MCOAL
UTILIZATION-
MAKEUP
WATER
41 |34
REAGENTS
WATER
RESERVOIR
ECONOMIZER i
AIR HEATER
ASH STORAGE
MOIST BOTTOM
ASH TO LANDFILL
I MILE
ESP ASH
STORAGE
DRY FLY ASH
TO LANDFILL
I MILE
MECHANICAL
EXHAUSTER
• UTILIZATION
RAINFALL
BOTTOM ASH LANDFILL
RAINFALL
FJ
27
,43
IREARFNTR
\ RUNOFF
\ 42 . WATFR
OVERFLOW
44.WATER
TO
DIRCHARGF
"RECYCLE
TO LANDFILL
Figure 19. Flow diagram. Base case 5, direct landfill of self-hardening ash.
-------
POWER PLANT TO LANDFILL. I MILE
ACCESS
ROAD
00
~s~f
T
1,050 FEET
FLOW »• :
MONITORING WELL — »
,
715 FEET
^
9
«-
BOTTOM
ASH
LANDFILL
648.000 YD3 VOLUME
- 902 FEET —
/
-1*
: — •"
TOPSOIL
STORAGE
362 FEET
-»
*—
d
260 FEET"
o *
EQUIPMENT
STORAGE OFFICE
AREA TRAILER
h
f
(
•
<&
1
>OI
1 —
^
LO
REAGENTS
\
•
"
^
~
w
^
^- —
«-
MONITORING WELL *3
: x f^ — x x x x 1
f —
24-FOOT RUNOFF CATCHMENT DITCH
MONITORING
WELL
WATER
AND
STORAGE
RECYCLE T
RUNOFF
" CATCHMEI
BASIN
WELL *2
FLY ASH
LANDFILL
2,571.000 YD3 VOLUME
0 LANDFILL
IT
1,617 FEET
-»
s>
2,
1.76
MC
. *
839 FEET 7 — *j
6-FOOT SECURITY FENCE '
MONITORING WELL
GROUNDWATER
FLOW TO RIVER
TOTAL LAND AREA, I 16 ACRES
Figure 20. Disposal site. Base case 5, direct landfill of self-hardening ash.
-------
COAL STORAGE
X—X—X—X—X—X
ROAD
DRY FLY ASH AND MOIST BOTTOM
ASH TRUCKS TO LANDFILL , I MILE
FUTURE
ROAD
Figure 21. Plot plan. Base case 5, direct landfill of self-hardening ash.
-------
TABLE 15. MATERIAL BALANCE
BASE CASE 5 - DIRECT LANDFILL OF SELF-HARDENING ASH
Stream No.
J
i.
)
4
rj
ft
/
8
9
JO
Description
Tnt-al stream. Ib/hr
Stream components, Ib/hi
Ash
Water
Air
Ft3/min. 60°F
Gal/min
Percent Solids
1
Coal ash
to furnace
47,730
47,730
2
Ash to
economizer
38,180
38,180
3
Ash collected
from economizer
1.190
1.190
4
Air intake to
economizer ash
pneumatic system
71
71
Ifi
5
Economizer ash
in pneumatic
system
1,260
1,190
71
Stream No.
1
2.
i
4
j
6
/
8
y
11L
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Percent solids
6
Ash to
air heater
36,990
36,990
7
Ash collected
from air heater
1,190
1,190
8
Economizer -air
heater ash in
pneumatic system
2,450
2,380
71
9
Ash to ESP
35,800
35,800
1U
Air intake to
ESP ash
pneumatic system
1.066
1.066
232
Stream No.
1
;
1
4
r>
ft
/
8
y
10
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
Ft^/min, 6QOF
Gal /min
Percent solids
11
ESP ash in
pneumatic
system
36,580
35,510
1,066
12
Ash to FGD
system
285
285
13
Ash in FGD
waste
143
143
14
Ash to stack
142
142
15
Economizer- air
heater ash
from primary
collector
1,970
1,970
Stream No.
1
i
)
4
'>
6
7
8
Y
10
Description
Total stream, Ib/hr
Stream components, Ib/h:
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Percent solids
16
Economizer- air
heater ash
from secondary
collector
340
340
17 1
Economizer air
heater ash
from bag filter
70
70
1 T3 1
Air from
economizer* ash
heater ash
bag filter
71
71
16
R 1
Economizer air
heater ash
from storage
•i,im
2,380
1 ?D !
ESP ash
from primary
collector
29,370
29,370
(continued)
100
-------
TABLE 15 (continued)
Stream No.
1
L
i
4
3
ft
7
8
9
JO
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
Ft^/min, 60°F
Gal/min
Percent solids
21
ESP ash
from secondary
collector
5,080
5,080
22
ESP ash
from bag filter
1,060
1,060
23
Air from KSP
ash bag filter
1.06ft
1.066
232
24
Air from
mechanical
exhauster
1.137
1.137
248
25
ESP ash
utilization
0
Stream No.
1
2
i
4
b
6
7
8
9
UL
Description
Total stream, Ib/hr
Stream components, Ib/hi
Ash
Water
Air
Ft3/min, 60°F
Gal/min
Percent solids
26
ESP ash
from storage
35,510
35,510
27
Recycle water
to onsite
moisturizer
7,810
40
7,770
16
28
Fly ash
landfill
45,660
37,890
7,770
83
29
Rainfall
to fly ash
landfill
65,760
65,760
132
30
Runoff water
from fly ash
landfill to
treatment
65,800
40
65,760
132
Stream No.
1
2
i
4
5
6
/
«
9
10
Description
Total stream, Ib/hr
Stream components. lb/h:
Ash
Water
Air
HjSOi
FtJ/min. 60°F
Gal/min
Jercent solids
31
Water to bottom
ash hopper
38,990
40
38,950
78
32
Slurry
to bottom
ash pump
57,600
9,600
48,000
106
16.7
33
Reagents for
water reservoir
treatment
420
420
0.4
34
Makeup water
640
640
1.3
35
Underflow from
settling tank
3,600
450
3,150
6.8
Stream No.
1
2
i
4
b
6
7
8
y
10
Description
Total stream, Ib/hr
Stream components, lb/h
Ash
Water
Air
Ft^/min, 60°F
Gal/min
Percent solids
36
Water from
dewatering bin
:o settling tank
50,590
500
50,090
101
1
37
Bottom ash
utilization
6
38
Dewatered
bottom ash
to landfill
10,610
9,550
1,060
50
39
Bottom ash
landfill
1 0 , 600
9,540
1 ,060
90
40
Rainfall
to bottom
ash landfill
21,JHO
21,380
43
(continued)
101
-------
TABLE 15 (continued)
I
i
)
4
5
h
7
8
9
JO
Stream No.
Description
Total stream. Ib/hr
Stream components, Ib/hr
Ash
Water
Air
H2S04
Ft'/min, 60"F
Gal/min
Percent solids
41
Runoff water
from bottom ash
landfill to
treatment
:H.J9U
iu
21.J8U
ij
42
Combined
runoff water
from landfill
to treatmenc
87,190
SO
87,140
174
43
Reagents for
landfill water
treatment
" " 60
60
0.06
44
Treated
landfill water
to discharge
79,440
10
79,430
159
45
Overflow
water from
settling tank
48,490
60
48,430
97
1
2
!
/^
5
6
7
8
9
18
Stream No.
Description
Total stream, Ib/hr
Stream components, Ib/hr
Ash
Water
Air
FtVmin, 60°F
Gal/min
Percent solids
46
Water
to bottom
ash slurry
9,060
iu
9,050
18
47
Underflow
from water
reservoir
1,500
10
1,490
j
ft
7
8
9
10
102
-------
TABLE 16. EQUIPMENT LIST, DESCRIPTION, AND MATERIAL COST
BASE CASE 5 - DIRECT LANDFILL OF SELF-HARDENING ASH
Material cost,
delivered,
Item (number); description 1982 k$
Area l--Fly Ash Collection and Transfer
1. Economizer ash hoppers (4): Inverted pyramid-type hopper, 22
15 ft long x 15 ft wide x 13 ft deep, thermally isolated
design, constructed of 1/2-in. carbon steel plate
2. Air heater ash hoppers (4): Inverted pyramid-type hopper, 17
15 ft long x 7 ft wide x 13 ft deep, constructed of 1/2-
in. carbon steel plate, insulated
3. ESP ash hoppers (32): Inverted pyramid-type hopper, 18 317
ft long x 12 ft wide x 13 ft deep, constructed of 1/2-
in. carbon steel plate, heat traced and insulated
4. Economizer-air heater ash collection and transfer system 96
comprising (1):
a. Vacuum pneumatic conveying lines for economizer-air
heater ash (1): Pipelines and pipe fittings for
vacuum pneumatic conveyance of ash, 5 ton/hr
conveying capacity with 600-ft equivalent length
system, 4-in. I.D. branch lines and 5-in. I.D. main
lines, nickel-chromium cast iron pipe with Ni-Hard®
or equivalent pipe fittings
b. Ash and air inlet valves (8): Self-feeding
materials handling valve, electrically actuated, air
operated, 12-in. I.D. ash inlet, 4-in. I.D. ash outlet,
cast iron body, stainless steel slide gate; each
assembly includes two spring-loaded, air-inlet check
valves with cast iron bodies
c. Line segregating valves (5): Segregating slide
valve, electrically actuated, air operated for on-
off control of each branch conveying line, 4-in. I.D.
port, cast iron body, stainless steel slide gate
d. Vacuum breaker valves (1): Vacuum breaker valve for
control of vacuum in air line from bag filter, 5-
in. I.D. port, cast iron body
(continued)
103
-------
TABLE 16 (continued)
Material costt
delivered,
Item (number); description 1982 k$
e. System control unit (1): Automatic sequence control
unit to control the programmed operation of
materials handling valves, line segregating valves,
and mechanical exhauster; includes gauges for manual
reading and override switches for manual operation
5. Economizer-air heater ash separation system comprising 21
(1):
a. Primary air-ash separator (1): Primary centrifugal
separator with tangential air-ash inlet, cyclone-
type vortex finding sleeve, and top vertical air
outlet; two-gate, three-chamber ash removal and air
lock provision cycled for continuous vacuum
operation; 3 ft diameter x 10 ft high, 3.1 ton/hr
capacity; carbon steel shell, Ni-Hard liners in high-
velocity compartment
b. Secondary air-ash separator (1): Secondary
centrifugal separator similar to primary unit, 0.6
ton/hr capacity
c. Air-ash bag filter (1): Bag filter for air-ash service
at 150°F, 19-in. Hg vacuum, 150-ft2 cloth area,
cycled bag shaker and air-lock delivery to storage
bin, 0.1 ton/hr capacity
6. ESP ash collection and transfer system comprising (1): 114
a. Vacuum pneumatic conveying lines for ESP ash (1);
Pipelines and pipe fittings for vacuum pneumatic
conveyance of ash, 36 ton/hr conveying capacity with
600-ft equivalent length system, 5-in. I.D. branch
lines and 8-in. I.D. main lines, nickel-chromium cast
iron pipe with Ni-Hard or equivalent pipe fittings
b. Ash and air inlet valves (32): Self-feeding materials
handling valve, electrically actuated, air operated,
12-in. I.D. ash inlet, 6-in. I.D. ash outlet, cast iron
body, stainless steel slide gate; each assembly
includes two spring-loaded, air-inlet check valves
with cast iron bodies
(continued)
104
-------
TABLE 16 (continued)
Material cost,
delivered,
Item (number); description 1993 k$
c.> Line segregating valves (5): Segregating slide
valve, electrically actuated, air operated for on-
off control of each branch conveying line, 5-in. I.D.
port, cast iron body, stainless steel slide gate
d. Vacuum breaker valves (l)s Vacuum breaker valve for
control of vacuum in air line from bag filter, 8-
in. I.D. port, cast iron body
e. System control unit (1): Automatic sequence control
unit to control the programmed operation of
materials handling valves, line segregating valves,
and mechanical exhauster; includes gauges for manual
reading and override switches for manual operation
7. ESP ash separation system comprising (1): 42
a. Primary air-ash separator (1): Primary centrifugal
separator with tangential air-ash inlet, cyclone-
type vortex finding sleeve, and top vertical outlet;
two-gate, three-chamber ash removal and airlock
provision cycled for continuous vacuum operation;
4.5 ft diameter x 14 ft high; 30 ton/hr capacity,
carbon steel shell, Ni-Hard liners in high-velocity
compartment
b. Secondary air-ash separator (1): Secondary
centrifugal separator similar to primary unit except
3 ft diameter x 10 ft high for 5 ton/hr capacity
c. Air-ash bag filter (1): Bag filter for air-ash
service at 15QOF, 19-in. Hg vacuum, 900-ft2 cloth
area, cycled bag shaker and air-lock delivery to
storage bin, 1 ton/hr capacity
8. Mechanical exhausters for economizer-air heater and ESP 64
ash collection and transfer systems (2+1 spare)?
Mechanical exhauster, two-impeller, straight-lobe type,
760 aft3/min air at 19-in. Hg vacuum and 150°F, 8-in.
I.D. inlet, connected to common vacuum plenum, equipped
with silencer and inline prefilter, 75 hp
Total. Area 1 693
(continued)
105
-------
TABLE 16 (continued)
Material cost,
delivered,
Item (number) t description 1982 k$
Area 2—Fly Ash Conveyance to Disposal Site
1« Economizer-air heater ash storage bin (1): Economizer- 206
air heater ash storage bin, 14 ft diameter x 16 ft high,
2,460-ft3 volume, with bin-air fluidizing system and,
vent filter, elevated construction for 22-ft railroad
clearance, carbon steel plate, 5 hp
2. ESP ash storage bin (1): ESP ash storage bin, 32 ft 379
diameter x 44 ft high, carbon steel construction, 35,000-
ft3 volume, with bin-air fluidizing system and vent
filter, elevated construction for 22-ft railroad
clearance, carbon steel plate, 10 hp
3. Trucks for hauling economizer-air heater ash and ESP ash 248
from storage bins to fly ash landfill (2+1 spare):
Tandem-axle, 4 rear-wheel-drive tank truck, 15 yd3
capacity, with covered ash haul body, tailgate skirted
and equipped with water spray nozzles for dust control,
400-gal water tank, water pump capacity of 40 gpm at 40
psig, water pump driven by power takeoff, 44,000-lb
suspension, 6-forward speed manual transmission 237-hp
diesel engine
Total. Area 2 S3J
Area 3—Fly Ash Disposal Site
1. Flv ash landfill (1): Fly ash landfill, 1,617 ft (l,630)a
square with 1-ft-thick clay liner, volume of 2,571,000
yd3, constructed in one 20-ft lift with edge sloped
upward at 1-vertical to 2-horizontal (27o), edges and
top covered as filled with 1/2-ft-thick layer of clay
and 1-1/2-ft-thick layer of topsoil, 20-ft finished
height at edge with top sloped upward to center of
landfill at 1-vertical to 29-horizontal (20), landfill
surrounded by runoff and leachate collection ditch 24 ft
wide x 2.5 ft deep with 1-ft-thick clay liner; ditch
drains to common 260-ft-square catchment basin with 1-ft-
thick clay liner; site includes 362-ft-square common
topsoil storage area, office trailer with sanitary
facilities, equipment storage area, 24-ft-wide access
(continued)
106
t^^S^iSpps^
-------
TABLE 16 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
roads, onsite water supply well and three .peripheral mon-
itoring wells; landfill periphery is enclosed by 6-ft-
high security fence
2. Dozer for moving ash and earth at landfill (1): D4E 59
Caterpillar or equivalent track-type with 10-ft-long U-
shaped blade, 75-hp diesel engine (costed 80% in Area 3
and 20% in Area 7)
3. Compactor for ash at landfill (1): Vibratory sheepsfoot 70
compactor, self-propelled, Raygo 420 C or equivalent
(costed 80% in Area 3 and 20% in Area 7)
4. Tank trucks for dust control at landfill (2): Tandem- 66
axle, 4 rear-wheel-drive tank truck with spray nozzle boom
attachment, and pumping system, 2,000-gal fiberglass
tank, 130-hp diesel engine (costed 80% in Area 3 and 20%
in Area 7)
5. Front-end loader for stripping and restoring topsoil (1): 93
950 Caterpillar or equivalent with 3-yd3 bucket, 130-hp
diesel engine (costed 80% in Area 3 and 20% in Area 7)
6. Dozer for ash handling (1): DE Caterpillar or equivalent 42
track-type with 62-hp diesel engine (costed 80% in Area 3
and 20% in Area 7)
7. Service truck for fuel, lubricants, and field service (1): 20
Service truck with 500-gal cargo tank for diesel fuel
and cargo space for lubricants and other field service
items (costed 80% in Area 3 and 20% in Area 7)
Total. Area 3 3SO
Area 4--Fly Ash Water Treatment and Recycle of Water
(Costed 80% in Area 4 and 20% in Area 8)
1. Sulfuric acid storage tank for pH control of water to 2
discharge (1): Cylindrical steel tank 5 ft 7 in.
diameter x 5 ft 7 in. high, 1,000 gal, flat bottom and
closed flat top, carbon steel; all-weather housing
(continued)
107
-------
TABLE 16 (continued)
Material cost,
delivered,
Item (number): description 1982 k$
2. Metering pump for sulfuric acid (1+1 spare): Positive 2
displacement metering pump 0.01 to 1 gpm, 0 psig, with
flow rate controlled by a pH controller, Carpenter 20®
alloy or similar corrosion resistance to 93% sulfuric
acid; 0.25-hp
3. Agitator for mixing of treated water (1): Agitator with 3
24-in.-diameter nickel-chromium blade; 5 hp
4. Pump for solids (1+1 spare): Centrifugal pump, 20 gpm, 1
20 psig, carbon steel body and impeller, 0.5 hp
5. Automatic sampler for water to discharge (1): Automatic 4
sampler with sample size controlled by flow rate,
refrigerated storage of composite sample; all-weather
housing
Total. Area 4 12
Area 5--Bottom Ash Collection and Transfer
1. Water supply pumps for bottom ash hopper and slurry (1 + 29
1 spare): Centrifugal pump, 385 gpm, 250-ft head,
carbon steel body and impeller, 50 hp
2. Bottom ash hopper assembly (1): Double-V hopper with 310
2,540-ft capacity for 12-hr ash containment, supported
independently of furnace-boiler and mated to furnace
through a water seal trough spanning the furnace seal
plate, hopper body of 3/8-in.-thick carbon steel plate,
hopper lined with monolithic refractory 9 in. thick in
upper section and 6 in. thick in lower section, stain-
less steel seal trough and overflow weirs, assembly
includes poke doors, lighted observation windows, access
doors and hydraulically operated ash exit doors; each V-
section of hopper includes two hopper-type, double-roll
grinders with cast iron body and 10-in.-diameter x 2-ft-
long manganese steel rolls; 50 hp
Total. Area 5
(continued)
108
-------
TABLE 16 (continued)
Material cost,
delivered,
Item (number); description 1982 k$
Area 6—Bottom Ash Conveyance to Disposal Site
1. Slurry pumps for pipeline conveyance (1+1 spare): 44
Centrifugal slurry pumps, 425 gpm, 150-ft head, Ni-Hard
liner and impeller, 30-hp motor
2. Shutoff and crossover valves (10): Air-operated gate 23
valve, 8-in. I.D. port, Ni-Hard
3. One-eighth mile basalt-lined slurry pipeline to (46)a
dewatering bins, normal use (1): Pipeline comprising
37 18-ft-long sections of flanged, basalt-lined steel
pipe, 8-in. I.D. and four basalt-lined elbows or bends,
8-in. I.D.
4. Spare slurry pipeline to dewatering bins (1): Pipeline (12)a
comprising 17 40-ft-long sections of flanged steel pipe,
8-in. I.D., schedule 80 carbon steel and 4 hardened elbows
or bends, 8-in. I.D.
5. Dewatering bins for bottom ash slurry (2): Conical- 378
bottom dewatering bins, 25-ft-diameter x 15-ft-high
cylindrical section, 19-ft-high cone, 9,000 ft3, stain-
less steel floating decanter and movable drainpipe,
stationary decanters in conical section, erected for 22-
ft railroad clearance, carbon steel bin, stainless steel
decanter drum
6. Trucks for hauling moist bottom ash to bottom ash landfill 48
(1+1 spare): Dump truck with ash haul body, 7-yd3
capacity, 16,000-lb suspension, 85-hp diesel engine
Total. Area 6 493
Area 7—Bottom Ash Disposal Site
1. Bottom ash landfill (1): Bottom ash landfill, 902-ft (407)a
square with 1-ft-thick clay liner, volume of 648,000
yd3, constructed in one 20-ft lift with edge sloped
upward at 1-vertical to 2-horizontal (27°), edges and
top covered as filled with 1/2-ft-thick layer of clay
and 1-1/2-ft-thick layer of topsoil, 20-ft finished
(continued)
109
-------
TABLE 16 (continued)
Material costt
delivered,
Item (number); description 1992 k$
height at edge with top sloped upward to center of
landfill at 1-vertical to 29-horizontal (2o), landfill
surrounded by runoff and leachate collection ditch 24 ft
wide x 2.5 ft deep with 1-ft-thick clay liner; ditch
drains to common 260-ft-square catchment basin with 1-ft-
thick clay liner; site includes 362-ft-square common
topsoil storage area, office trailer with sanitary
facilities, equipment storage area, 24-ft-wide access
roads, onsite water supply well and 2 peripheral
monitoring wells; landfill periphery is enclosed by 6-ft-
high security fence
2. Dozer for moving ash and earth at landfill (1): Same 15
dozer as in Area 3, Item 2 (costed 20% in Area 7 and 80%
in Area 3)
3. Compactor for ash at landfill (1): Same compactor as 18
Area 3, Item 3 (costed 20% in Area 7 and 80% in Area 3)
4. Tank trucks for dust control at landfill (2): Same trucks 17
as in Area 3, Item 4 (costed 20% in Area 7 and 80% in
Area 3)
5. Front-end loader for stripping and restoring topsoil (1): 23
Same loader as in Area 3, Item 5 (costed 20% in Area 7
and 80% in Area 3)
6. Dozer for ash handling (1): Same dozer as in Area 3, 10
Item 6 (costed 20% in Area 7 and 80% in Area 3)
7. Service truck for fuel, lubricants, and field service (1): 5
Same service truck as in Area 3, Item 7 (costed 20% in
Area 7 and 80% in Area 3)
Total. Area 7 8_S
Area 8--Bottom Ash Water Treatment and Recycle of Water
/
1. Settling tank for clarifying water from dewaterin .bins 73
(1): Settling tank, 50 ft diameter x 15 ft deep,
220,000 gal, carbon steel
(continued)
110
-------
TABLE 16 (continued)
Material cost.
delivered,
Item (number); description 1982 H$
2. Water reservoir for bottom ash dewatering system (1): 47
Water reservoir, 35 ft diameter x 15 ft deep, 108,000
gal, carbon steel
3. Recycle pump for underflow solids from settling tank and 3
water reservoir (1): Centrifugal pump, 100 gpm, 100-ft
head, carbon steel body and impeller, 5 hp
4. Sulfuric acid storage tank for pH control of return water 2
from water reservoir (1): Cylindrical steel tank 5 ft
7 in. diameter x 5 ft 7 in. high, 1,000 gal, flat bottom
and closed flat top, carbon steel; all-weather housing
5. Metering pump for sulfuric acid to return water (1); 2
Positive displacement metering pump 0.01 to 1 gpm, 0
psig, with flow rate controlled by a pH controller,
Carpenter 20 alloy or similar corrosion resistance to
93% sulfuric acid; 0.25 hp
6. Sulfuric acid storage tank for pH control of water to 0.5
discharge (1): Same tank as in Area 4, Item 1 (costed
20% in Area 8 and 80% in Area 4)
7. Metering pump for sulfuric acid to discharge water (1 + 0.5
1 spare): Same pump as in Area 4, Item 2 (costed 20% in
Area 8 and 80% in Area 4)
8. Agitator for mixing of treated water (1): Same agitator 0.75
as in Area 4, Item 3 (costed 20% in Area 8 and 80% in
Area 4)
9. Piifnp for solids slurry from water treatment (1+1 spare): 0.25
Same pump as in Area 4, Item 4 (costed 20% in Area 8 and
80% in Area 4)
10. Automatic sampler for water to discharge (1): Same 1
sampler as in Area 4, Item 5 (costed 20% in Area 8 and
80% in Area 4)
Total. Area 8 130
Total, Base Case 5 2,938
Costs shown in parentheses are informational and are not included in
area or base case totals for equipment material costs.
Ill
-------
Ash Collection
The ash collection and storage systems are the same as those described
for base case 4 except that some equipment sizes are reduced because of the
smaller quantities of ash. The fly ash system is designed for 36 tons/hr
instead of the 48 tons/hr of base case 4. Five-inch main conveying lines,
smaller separators and storage silos, and a smaller mechanical exhauster are
used. Smaller fly ash and bottom ash hoppers and smaller slurry pumps,
dewatering bins, and recycle water tanks are used.
Ash Transportation
Fly ash is dumped without moisturizing into 44,000 Ib, 20 yd^ , ash-
haul-body dump trucks. The trucks are covered and equipped with tailgate-
mounted water tanks. At the landfill the fly ash is unloaded through the
moisturizers to provide dust control, additional water is added by tank truck,
and the moist ash is immediately spread and compacted. Two fly ash trucks are
used on a 56-minute cycle time. Bottom ash is transported in a 7 yd^ dump
truck. The same two shift/day operating schedule used for the other base
cases is used.
Landfill
The landfill design and operation is basically the same as the landfill
in base case 4. An additional water truck is provided, however. The fly ash
landfill occupies 60 acres, has a 2.6 million yd3 disposal volume, and has a
center height of 47 feet. The bottom ash landfill occupies 19 acres, has a
0.6 million yd^ disposal volume, and a center height of 35 feet. A 90
Ib/ft-* dry bulk density and a 17% moisture content are used for the fly ash
landfill while the bottom ash landfill has 10% moisture. The disposal site
occupies 116 acres including roads, facilities, and runoff and seepage
collection facilities.
112
-------
RESULTS
The ash disposal costs discussed below are based on similar procedures
and formats used in TVA FGD and FGD-waste-disposal economic evaluations. The
need of such compatability lies not only in the requirements of evaluation
consistency but also in the interrelationships of ash disposal and FGD waste
disposal. The overall costs are analyzed from several aspects intended to
provide cost breakdowns for comparison of the results with various alternative
methods. The total costs are expressed as the sum of various components of
direct and indirect costs, and are also itemized separately for fly ash and
bottom ash. In addition, the costs are expressed in modular form by
functional area (collection, transportation, disposal site, and water
treatment and recycle) and by type of equipment or facility (hoppers, process
equipment, pipelines, mobile equipment, and disposal site).
DIRECT CAPITAL INVESTMENT
Equipment Costs
Major equipment costs are shown in the equipment lists for each process
(Tables 8, 10, 12, 14, and 16). Depending on commercial practice, these costs
are for individual items of equipment or package units. Because of design and
cost differences between suppliers, the costs are more applicable to
comparisons between conceptual design cases than to costs for a particular
vendor's system under site-specific conditions.
The equipment costs in Tables 8, 10, 12, 14, and 16 are delivered costs
in 1982 dollars and include tax and freight. For slurry pipelines, ponds, and
landfills the costs are shown in parentheses but are not included in area
totals. In this study the slurry pipelines are considered, along with other
piping, as supporting equipment. This procedure allows for the inclusion of
slurry pipelines as a transportation function.
The equipment costs for the five base cases are summarized by type of
equipment and by area in Table 17. In this table, the costs of hoppers and of
mobile equipment are stated separately.
Hoppers are included in this study because the operating costs for ash
collection begin with operation of the hoppers. (Therefore operating labor,
utilities, and related costs for hopper operation are assigned in the annual
revenue requirements.) At the same time, the cost of hoppers exceeds most
other equipment costs, ranging from 61% to 23% of the total equipment cost.
These cost levels show that hoppers contribute substantially to the equipment
costs for ash collection and that their inclusion or exclusion must be
113
-------
TABLE 17. COSTS OF DELIVERED EQUIPMENT
1982 k$
Process equipment
Base
case 1
Base
case 2
Base
case 3
Base
case 4
Base
case 5
Fly Ash
Hoppersa 421 421
Collection 285 285
Transportation 44 44
Transportation vehicles 0 0
Disposal vehicles 0 0
Water treatment 12 155
Subtotal fly ash 762 905
421
285
39
565
334
2A
1,668 2,120
1,888
Bottom Ash
Hoppersb 352 352 352 352 310
Pumps 34 34 18 34 29
Transportation 110 110 108 505 445
Transportation vehicles 0 0 225 53 48
Disposal vehicles 0 0 84 84 88
Water treatment 1 39 6_ 135 130
Subtotal bottom ash 499 535 793 1,163 1,050
Total Ash
Hoppers 773
Process equipment 488
Vehicles 0_
Total equipment 1,261
1,440
773
480
1.208
2,461
773
1,828
682
3,283
666
1,538
734
2,938
a. Economizer, air heater, and ESP hoppers.
b. Bottom ash hoppers.
114
SSsffiiasiiSaSSiWIP
-------
recognized. The fly ash hopper costs are based on ESP collection using a
single specific collection area (SCA) in all base cases. Changes in the
method of collection or SCA could significantly change hopper costs by
changing the size of the ESP base to which the hoppers are attached. Since
the tonnage of bottom ash is only one-quarter that of fly ash, the cost of
bottom ash hoppers is much higher than that of fly ash hoppers relative to the
amount of ash collected.
Cases 1 and 2 do not have mobile equipment since the ash is transported
by slurry pipelines whose costs are not included as equipment. In base
case 3 mobile equipment cost is the largest cost area and in base cases 4
and 5 it constitutes 20% to 25% of the total equipment cost.
Fly ash collection equipment in base case 4 is more expensive than in
base cases 1, 2, and 3 because base case 4 has mechanical exhausters and
separate collection systems for ESP ash and for economizer and air heater
ash. Base case 4 has higher transportation costs, excluding vehicles, because
ash storage bins and moisturizers are included as transportation equipment.
With no mobile equipment, base case 1 has the lowest total equipment
costs. The addition of pond water treatment and reuse in base case 2 raises
equipment costs by a moderate 179 k$ to 1,440 k$. In base case 3, the cost of
process equipment is slightly lower than in base case 1 because of lower pump
costs for the shorter pipelines but the cost of vehicles, including those
required for removing the ash from the ponds, substantially increases the
total equipment cost.
Base case 4 has higher costs for fly ash handling equipment. Its fly ash
hoppers costs are the same as those in base cases 1, 2, and 3 but the process
equipment cost is increased by equipment needed for dry ash collection,
storage, and moisturizing for trucking to landfills. Base case 4 also has
high processing costs for the mechanized bottom ash dewatering system. Thus,
the equipment costs for base case 4 are the highest of the group. For base
case 5, the slightly lower equipment cost results mainly from a lower ash
tonnage. This reduction is counteracted to some degree by more expensive
trucks for conveyance of dry fly ash and by more costly moisturizing at the
landfill.
The above comparisons illustrate that the five base cases have widely
differing profiles of uninstalled equipment costs. At this level, the costs
indicate differences in equipment needs rather than the overall economic
standings of the base case processes.
Installed Equipment Costs
The direct capital investments for the five base cases are detailed in
Tables 18 through 22. Costs in the equipment lists (Tables 8, 10, 12, 14, and
16) are the basis for the capital investment determinations. They are shown
as material costs under the equipment category, along with installation labor
costs. Field installation component costs consist of piping and insulation,
ductwork, foundations, site preparation, structural, electrical,
instrumentation, paint and buildings, as well as costs for services and
utilities. Overall costs are itemized by functional area. The
column "collection" includes all costs associated with receiving the ash from
115
-------
TABLE 18. INSTALLED PROCESS EQUIPMENT DIRECT CAPITAL INVESTMENT -
BASE CASE 1, DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Equipment
Material
Labor
Piping and insulation
Material
Labor
Ductwork, chutes, and supports
Material
Labor
Concrete foundations
Material
Labor
Excavation, site preparations
Railroad and roads
Structural
Labor
Electrical
Material
Labor
Material
Labor
Paint and miscellaneous
Material
Labor
Buildings
Material
La>or
Disposal site
Ponds
Landfills
Subtotal
Services, utilities, and miscellaneous
Total direct investment
Percent of total direct investment
Flv
ash. 1QS? kS
Rorrnm atsh 1QR? k$
Transportation Water
Collec- to disposal Disposal treatment
tion site site and recycle Subtotal
706
344
19
15
2
4
2
4
0
5
8
24
43
6
3
1
7
0
0
0
-
1,193
48
1,241
8.2
44
26
389
156
1
2
38
105
41
29
58
6
11
3
1
1
4
0
0
0
915
37
952
6.3
12
8
2
2
0
0
1
2
0
0
0
2
5
8
5
1
6
0
0
8,509 0
8,509 54
340 2
8,849 56
58.3 0.4
762
378
410
173
3
6
41
111
41
34
66
32
59
17
9
3
17
0
0
8,509
~
10,671
427
11,098
73.2
Transportation Water
Collec- to disposal Disposal treatment
386
215
38
24
0
0
8
24
0
19
52
13
20
4
2
2
14
0
0
0
-
821
33
854
5.6
110
18
516
207
0
0
9
27
40
0
0
6
11
3
1
1
2
0
0
0
951
38
989
6.5
3
1
1
1
0
0
1
1
0
0
0
1
2
2
1
0
0
0
0
2,127 0
2,127 14
85 1
2,212 15
14.6 O.L
499
234
555
232
0
0
18
52
40
19
52
20
33
9
4
3
16
0
0
2,127
3,913
157
4,070
26.8
Total
installed
1,261
612
965
405
3
6
59
163
81
53
118
52
92
26
13
6
33
0
0
10,636
-
14,584
584
15,168
100. 0
% of total
direct
8.3
4.0
6.4
2.7
0.0
0.0
0.4
1.1
0.5
0.3
0.8
0.3
0.6
0.2
0.1
0.0
0.2
0.0
0.0
70.2
_
96.1
3.9
100.0
-------
TABLE 19. INSTALLED PROCESS EQUIPMENT DIRECT CAPITAL INVESTMENT -
BASE CASE 2, DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Fly Ash. 1982 kS
Investment Category
Equipment
Material
Labor
Piping and insulation
Material
Labor
Ductwork, chutes, and supports
Material
Labor
Concrete foundations
Material
Labor
Excavation, site preparations
Railroad and roads
Structural
Material
Labor
Electrical
Material
Labor
Instruments
Material
Labor
Paint and miscellaneous
Material
Labor
Buildings
Material
Labor
Disposal site
Ponds
Landfills
Subtotal
Services, utilities, and miscellaneous
Total direct investment
Percent of total direct investment
Transportation Water
Collec- to disposal Disposal treatment
t-inn site site and recycle Subtotal
706
344
19
15
2
4
2
It
0
5
8
24
43
6
3
1
7
0
0
0
-
1,193
48
1,241
7.8
44
26
389
156
1
2
38
105
41
29
58
6
11
3
1
1
4
0
0
U
-
915
37
952
6.0
155
43
145
58
0
0
16
42
0
0
0
12
20
12
8
3
18
12
16
8,509 0
-
8,509 560
340 22
8,849 582
55.9 3.7
905
413
553
229
3
6
56
151
41
34
66
42
74
21
12
5
29
12
16
8,509
-
11,177
447
11,624
73.4
Bottom Ash , 1982 kS
Transportation Water
Collec- to disposal Disposal treatment
tion site site and recycle
386
215
38
24
0
0
8
24
0
19
52
13
20
4
2
2
14
0
0
0
-
821
33
854
5.4
110 \
18
516
207
0
0
9
27
40
0
0
6
11
3
I
1
2
0
0
0
-
951
38
989
6.3
39
11
36
15
0
0
4
11
0
0
0
3
5
— 3
2
1
4
3
4
2,127 0
-
2,127 141
85 6
2,212 147
14.0 0.9
Subtotal
534
244
590
246
0
0
21
62
40
19
52
22
36
10
5
4
20
3
4
2,127
-
4,040
162
4,202
26.6
Total
installed
1,440
657
1,143
475
3
6
77
213
81
53
118
64
110
31
17
9
49
15
20
10,636
_
15,217
609
15,826
100.0
% of total
direct
9.1
4.2
7.2
3.0
0.1
0.1
0.5
1.3
0.5
0.3
0.7
0.4
0.7
0.2
0.1
0.1
0.3
0.1
0.1
67.2
.
96.2
3.8
100.0
-------
00
TABLE 20. INSTALLED PROCESS EQUIPMENT DIRECT CAPITAL INVESTMENT -
BASE CASE 3, HOLDING PONDS AND LANDFILL OF NONHARDENING ASH
Fly Ash. 1982 kS
Investment Category
Equipment
Material
Labor
Piping and insulation
Material
Labor
Ductwork, chutes, and supports
Material
Labor
Concrete foundations
Material
Labor
Excavation, site preparations
Railroad and roads
Structural
Material
Labor
Electrical
Material
Labor
Instruments
Material
Labor
Paint and miscellaneous
Material
Laborfc
Buildings
Material
Labor
Disposal site
Ponds
Landfills
Subtotal
Services, utilities, and miscellaneous
Total direct investment
Percent of total direct investment
Transportation Water
Collec- to disposal Disposal treatment
tinn site site and recycle Subtotal
706
344
19
15
2
4
2
4
0
5
8
24
43
6
5
1
7
0
0
0
0
1,195
48
1,243
13.0
604
26
115
46
1
2
12
34
12
26
56
6
11
3
1
1
4
0
0
0
0
960
38
998
10.4
334 24
0 16
4
4
0
0
2
4
0
0
0
4
10
16
10
2
12
0
0
2,534 0
1.491 0
4,359 108
174 5
4,533 113
47.4 1.2
1,668
386
138
65
3
6
16
42
12
31
64
34
64
25
16
4
23
0
0
2,534
1,491
6,622
265
6,887
72.0
Bottom Ash, 1982 k$
Trunsportation Water
Collec- to disposal Disposal treatment
tion site site and recycle
370
206
38
24
0
0
8
24
0
19
52
13
20
4
2
2
14
0
0
0
0
796
32
828
8.7
333
14
166
67
0
0
9
27
40
0
0
6
11
3
1
1
2
0
0
0
0
680
27
707
7.4
84 6
0 2
2
2
0
0
2
2
0
0
0
2
4
4
3
1
1
0
0
608 0
372 0
1,064 31
43 1
1,107 32
11,6 0.3
Subtotal
793
222
206
93
0
0
19
53
40
19
52
21
35
11
6
4
17
0
0
608
372
2,571
103
2,674
28.0
Total
installed
cost
2,461
608
344
158
3
6
35
95
52
50
116
55
99
36
22
8
40
0
0
3,142
1,863
9,193
368
9,561
100.0
% of total
direct
investment
25.7
6.4
3.6
1.7
0.0
0.1
0.4
1.0
0.5
0.5
1.2
0.6
1.0
0.4
0.2
0.1
0.4
0.0
0.0
32.9
19.5
96.2
3.8
100.0
-------
TABLE 21. INSTALLED PROCESS EQUIPMENT DIRECT CAPITAL INVESTMENT -
BASE CASE 4, DIRECT LANDFILL OF NONHARDENING ASH
Equipment
Material
Labor
Piping and insulation
Material
Labor
Ductwork, chutes, and supports
Material
Labor
Concrete foundations
Material
Labor
Excavation, site preparations
Railroad and roads
Structural
Material
Labor
Electrical
Material
Labor
Material
Labor
Paint and miscellaneous
Material
Labor
Buildings
Material
Labor
Disposal site
Landfills
Subtotal
Percent of total direct investment
Fly Ash . 1982
k$
Transportation Water
Collec- to disposal Disposal treatment
tion site site and recycle
834
406
19
15
2
4
3
7
0
5
8
24
48
6
3
2
14
0
0
0
1,400
56
17.3
940 334
328 0
19
15
1
2
32
85
6
20
35
6
11
0
0
2
14
0
0
0 1.946
1,516 2,280
61 j^
18.6 28.2
12
8
2
2
0
0
1
2
0
0
0
2
5
8
5
1
6
0
0
0
54
2
56
0.7
Bottom Ash , 1982 k$
Collec-
Subtotal tion
2,120
742
40
32
3
6
36
94
6
25
43
32
64
14
8
5
34
0
0
1.946
5,250
210
65.0
386
215
38
24
0
0
8
24
0
19
52
13
20
4
2
2
14
0
0
0
821
33
854
10.2
to disposal Disposal
site site i
558 84
252 0
66
29
0
0
23
61
1
12
28
2
7 —
0
0
1
8
0
0
0 487
1,048 571
42 23
1,090 594
12.9 7.1
Water
treatment
and recycle
135
41
34
15
0
0
25
64
0
8
14
4
9
5
3
26
0
0
387
15
402
4.8
Subtotal
1,163
508
138
68
0
56
149
1
39
94
19
36
48
0
487
2,827
in
2,940
35.0
Total
installed
cost
3,283
1,250
178
100
3
92
243
7
64
137
51
100
82
0
2,433
8,077
3? 3
8,400
100.0
7. of total
direct
investment
39.0
14.9
2.1
1.2
0.0
0.1
1.1
2.9
0.1
0.8
1.6
0.6
1.2
0.3
0.2
0.1
1.0
0.0
0.0
29.0
96.2
3.8
100.0
-------
TABLE 22. INSTALLED PROCESS EQUIPMENT DIRECT CAPITAL INVESTMENT -
BASE CASE 5, DIRECT LANDFILL OF SELF-HARDENING ASH
Investment Category
Equipment
Material
Labor
Piping and insulation
Material
Labor
Ductwork, chutes, and supports
Material
Labor
Concrete foundations
Material
Labor
Excavation, site preparations
Railroad and roads
Structural
Material
j , Labor
[\j Electrical
O Material
Labor
Instruments
Material
Labor
Paint and miscellaneous
Material
Labor
Buildings^
Material
Labor
Disposal site
Ponds
Landfills
Subtotal
Services, utilities, and miscellaneous
Total direct investment
Percent of total direct investment
Fly Ash , 1982
Transportation
Collec- to disposal Disposal
tion site site ;
693
337
16
12
2
3
3
7
0
2
3
21
39
6
3
2
14
0
0
-
0
1,163
46
1,209
16.7
833 350
263 0
15
12
1
2
26
68
5
16
28
4
9
0
0
2
11
0
0
- _
0 1,630
1,295 1,980
52 79
1,347 2,059
18.6 28.4
k$
Bottom Ash , 1982 k$
Water
treatment
and recycle Subtotal
12
8
2
2
0
0
1
2
0
0
0
2
5
8
5
1
5
0
0
-
0
53
2
55
0.8
1,888
608
33
26
3
5
30
77
5
18
31
27
53
14
8
5
30
0
0
-
1,630
4,491
180
4,671
64.5
Transportation Water
Collec- to disposal Disposal treatment
tion site site and recycle
339
178
32
20
0
0
7
20
0
16
43
11
17
4
2
2
11
0
0
_
0
702
28
730
10.1
493
209
66
29
0
0
19
50
1
11
25
2
7
0
0
1
8
0
0
_
0
921
37
958
13.2
88 130
0 39
34
15
0
0
21
52
0
7
11
4
9
5
3
4
22
0
0
_ _
407 0
495 356
20 14
515 370
7.1 5.1
Subtotal
1,050
426
132
64
0
0
47
122
1
34
79
17
33
9
5
7
41
0
0
_
407
2,474
99
2,573
35.5
Total
installed
cost
2,938
1,034
165
90
3
5
77
199
6
52
110
44
86
23
13
12
71
0
0
_
2,037
6,965
279
7,244
100.0
% of total
direct
investment
40.
14.
2.
1.
0.
0.
1.
2.
0.
0.
1.
5
3
3
2
0
1
1
7
1
7
5
0.6
1.
0.
0.
0.
1.
0.
0.
_
28.
96.
3.
100
2
3
2
2
0
0
0
1
1
9
.0
-------
the boiler, or ESP's; for bottom ash it is primarily hopper costs and for fly
ash it is primarily hoppers and pneumatic conveying equipment costs. The
column "transportation to disposal site" includes pipelines, trucks, and other
process equipment required for transportation. Depending on the particular
process, it includes dewatering bins, silos, pumps, and front loaders. The
column "disposal site" contains only ponds, landfills, and mobile equipment.
The column "water treatment and recycle" includes the facilities required for
the sampling and pH control of effluent water and for scale control of
recirculated transport water.
The pond and landfill construction costs are detailed in Table 23. The
costs shown represent only the disposal site construction costs and do not
include land or mobile equipment. The four largest cost areas involve the
movement and placement of earth. Because of this, pond construction costs are
almost five times those of landfills for comparable situations (base cases 1
and 2 compared with base case 4). Ponds require a larger area than landfills
for equivalent quantities of waste because of the lower bulk density of the
waste and the shallower waste depth. Landfills can be sloped upward from the
edge to the center whereas increasing pond depth requires an exponentially
increasing quantity of dike material. Ponds also require excavation of a
substantial quantity of subsoil for dike construction. As a result, the
construction cost for landfills even when fully capitalized is substantially
lower than that for ponds. Against this, however, must be weighed the higher
equipment costs and operating costs for landfills.
TOTAL CAPITAL INVESTMENT
Total capital investments for the five base cases are summarized in
Table 24. They consist of the direct capital investment plus indirect
investment, contingency, other capital investment, land, and working capital.
Detailed capital investment tables are included in Appendix A. Base case 1,
direct ponding of nonhardening ash without water reuse, represents an industry
standard, and can serve as a basis of comparison for other disposal practices
represented by base cases 2 through 4.
Base case 2, direct ponding of nonhardening ash with water reuse, is the
same as base case 1 except that the sluice water is treated and returned to
the power plant for reuse as sluicing water. Both direct capital investment
and total capital investment are increased about 4% by this addition.
The base case 3 capital investment is only two-thirds of that of base
case 1. The base case 3 capital investment for 5-year ponds and a 25-year
landfill are only one-half those of base case 1 for a 30-year pond. This
difference more than offsets the mobile equipment costs of base case 3.
Base case 4, direct landfill of nonhardening ash, differs from base
case 3 largely in capital investment for transportation and for the disposal
site. Direct investment for transportation in base case 4 is one-third less
than those of base case 3 because of the elimination of sluicing to the
temporary ponds and of ash removal from the ponds. This reduction in costs
occurs in spite of the addition of the bottom ash dewatering system and the
fly ash silos. Similarly, elimination of the temporary ponds reduces disposal
site direct investment by about one-half for base case 4, compared with base
case 3, or by three-quarters when compared with base case 1.
121
-------
ho
N>
TABLE 23. POND AND LANDFILL CONSTRUCTION COSTS
1982 k$
Land clearance
Excavation, soil storage
Dike construction
Liner installation
Catchment ditch, basin
Discharge ditch
Road construction on dikes
Site facilities: fences,
trailer/office, moni-
toring wells, access
roads
Reclamation
Total construction cost
Volume, Myd^
Base
Fly ash
pond
253
2,926
1,676
927
-
52
_
-
8,509
5.54
cases 1 and 2
Bottom ash
pond
90
1,049
633
295
-
29
_
-
2,127
1.39
Total
343
3,975
2,309
1,222
-
50
81
344
2,312
10,636
6.93
Fly ash
pond
69
810
594
216
0
25
_
-
2,534
.94
Base case 3
Bottom ash
pond
25
296
191
65
0
14
_
-
608
.23
Common
landfill
99
317
439
211
19
0
197
581
1,863
3.51
Total
193
1,423
785
720
211
45
39
393
1,196
5,005
(continued)
-------
TABLE 23 (continued)
NJ
U)
Base case 4
Base case 5
Fly ash
landfill
Bottom ash
landfill
Total
Fly ash
landfill
Bottom ash
landfill
Total
Land clearance
Excavation, soil storage
Dike construction
Liner installation
Catchment ditch, basin
Discharge ditch
Road construction on dikes
Site facilities: fences,
trailer/office, moni-
toring wells, access
roads
Reclamation
95
331
424
33
108
132
128
439
556
295
19
79
282
339
26
92
105
105
374
444
255
17
Total construction cost 1,946
Volume, Myd~
3.37
487
.84
222
774
204
638
2,433
4.21
1,630
2.57
407
0.65
2,037
3.22
-------
TABLE 24. BASE CASE SUMMARIES OF
CAPITAL INVESTMENTS
Direct capital Total capital
investment, investment,a
1982 k$ 1982 k$
Base Case 1
Fly ash
Bottom ash
Total
Base Case 2
Fly ash
Bottom ash
Total
Base Case 3
Fly ash
Bottom ash
Total
Base Case 4
Fly ash
Bottom ash
Total
Base Case 5
Fly ash
Bottom ash
Total
k$
11,098
4.070
15,168
11,624
4.202
15,826
6,887
2.674
9,561
5,460
2.940
8,400
4,671
2.573
7,244
$/kW
22.2
30.3
23.2
31.7
13.8
19.1
10.9
16.8
9.3
5-1
14.5
k$
18,881
6.979
25,860
19,801
7.221
27,022
11,628
4.501
16,129
9,652
5.101
14,753
8,190
4.455
12,645
$/kW
37.8
14.0
51.7
39.6
14.4
54.0
23.3
32.3
19.3
10.2
29.5
16.4
25.3
a. Total capital investment consists of
direct capital investment plus indirect
investment, contingency, other capital
investment, land, and working capital.
124
:?^^3^S^KI^
-------
The capital investment of base case 5, direct landfill of self-hardening
ash, cannot be compared directly with the similar base case 4 disposal
technique for nonhardening ash because the quantities of ash differ. For the
self-hardening ash the total ash rate is about 48,000 Ib/hr whereas it is
about 62,000 Ib/hr for the nonhardening ash. Consequently, costs related to
ash quantities are generally lower in all areas. Except for ash quantities,
however, the processes are similar in all areas except for the manner in which
the fly ash is transported. For the nonhardening fly ash, moisturizers
attached to the storage silos wet the ash as it is loaded into open-bed
trucks. The same trucks are used to transport bottom ash. For the self-
hardening fly ash moisturizers are attached to covered-bed trucks. Bottom ash
is hauled in separate trucks. In terms of capital investment the differences
in these two methods is minimal. The trucks for the self-hardening fly ash
are more expensive because of the covers and self-contained moisturizers but
this cost difference is counteracted by the elimination of bin moisturizers.
Consequently, the higher capital investment for direct landfill disposal of
nonhardening ash compared with direct landfill disposal of self-hardening ash
is essentially a result of the larger quantity of ash.
The major cost elements in capital investment for the five base cases are
shown in Table 25 as percentages of the total capital investment. The
comparisons show the differences in the distribution of capital investment
between ponding and landfill disposal cases. Disposal site capital investment
dominates the area costs in the pond cases whereas investments for landfill
disposal are more equally distributed among collection, transportation, and
the disposal site. Water treatment and transportation for reuse is a minor
element for both types of disposal. Land costs are proportionately lower for
landfill disposal than pond disposal.
TABLE 25. MAJOR COST ELEMENTS IN
CAPITAL INVESTMENT
Percentage of total
capital investment
Base case:
Cost Element
Ash collection
Ash transportation
Disposal site
Water treatment and recycle
8
7
43
-
8
7
43
3
13
10
35
1
16
18
20
3
16
18
20
3
Proportioned costs3
Land
34 31
8 8
34 38 38
755
a. Indirect investment, contingency, other capital
investment, working capital.
125
-------
ANNUAL REVENUE REQUIREMENTS
V
The annual revenue requirements for the five base cases are summarized in
Table 26. Detailed annual revenue requirement tables for each base case are
shown in Appendix A. The results shown in Table 26 are first-year annual
revenue requirements using levelized capital charges, as described in the
premises. Levelized annual revenue requirements, representing annual revenue
requirements inflated and discounted over the 30-year life of the power plant,
are also shown in Appendix A.
Base case 1, direct ponding of nonhardening ash without water reuse,
representing established practice, serves as a basis of comparison with other
disposal practices represented by base cases 2 through 4. Base case 2, direct
ponding of nonhardening ash with water reuse, differs from base case 1 only in
the treatment and return of the sluice water to the power plant. This
increases the annual revenue requirements by 7%, from 1.85 to 1.98 mills/kWh.
The largest increase in direct cost is for maintenance, followed by
electricity, water treatment reagents, operating labor, and sampling and
analyses. There is only a small direct cost saving in water costs.
Base case 3, temporary ponding of nonhardening ash and final disposal by
landfill, has annual revenue requirements of 1.91 mills/kWh, which are not
appreciably different from the direct ponding annual revenue requirements of
base cases 1 and 2. The direct costs of base case 3, however, are twice those
of base cases 1 and 2. The higher direct costs for base case 3 are primarily
a result of much higher labor costs (0.32 mills/kWh versus 0.08 mills/kWh for
base case 1) and large costs for diesel fuel (0.07 mills/kWh) and dredging fly
ash from the temporary pond (0.07 mills/kWh), which do not appear in direct
ponding disposal. In contrast, the indirect costs of base case 3 are
substantially lower, primarily because of the lower capital charges.
Base case 4, direct landfill of nonhardening ash, has lower annual
revenue requirements, 1.66 mills/kWh, than either direct ponding (base cases 1
and 2) or temporary ponding followed by landfill (base case 3). Direct costs
for base case 4 are similar in structure to base case 3 although generally
lower because the pipeline transportation electricity and maintenance costs
and the pond dredging and loading costs are eliminated. The most important
differences are a reduction of 0.07 mill/kWh in dredging, 0.04 mill/kWh in
labor, and 0.03 mill/kWh in diesel fuel. In contrast, overall maintenance
costs are 0.02 mill/kWh higher for base case 4. Indirect costs for base
case 4 are also similar in pattern to base case 3 but somewhat lower because
of the lower overheads and capital charges.
Base case 5, direct landfill of self-hardening ash has the lowest annual
revenue requirements of the five base cases, 1.57 mills/kWh. Most of the
differences between the annual revenue requirements of base case 5 and base
case 4, direct landfill of nonhardening ash, are results of the smaller
quantity of ash in base case 5. Differences in direct costs related directly
to process differences are due to higher labor and water treatment costs for
base case 5. Labor costs are 8% higher because of separate trucks for fly and
bottom ash transportation and the more complicated moisturizing of fly ash at
the landfill. Water treatment costs are four times higher in base case 5
because of the high alkalinity of the ash.
126
-------
TABLE 26. BASE CASE SUMMARIES OF ANNUAL REVENUE REQUIREMENTS
Direct costs.
Base Case 1
Fly ash
Bottom ash
Total
Base Case 2
Fly ash
Bottom ash
Total
Base Case 3
Fly ash
Bottom ash
Total
Base Case 4
Fly ash
Bottom ash
Total
Base Case 5
Fly ash
Bottom ash
Total
k$
515
211
828
605
141
948
1,411
481
1,892
1,004
544
1,548,,
996
5S5
1,581
Mills/kWh
0.19
Q.ll
0.30
0.22
0.12
0.34
0.51
0.18
0.69
0.36
0.20
0.56
0.36
0.21
0.57
1984 $
$/ton, drv
3.75
9.12
4.82
4.41
9.98
5.52
10.28
14.01
11.03
7.31
15.84
9.02
9.49
22.28
12.05
Total annual revenue. 3 1984 $
k$
3,571
1.514
5,085
3,842
1.595
5,437
3,848
1.4Q2
5,250
2,954
1.6QQ
4,554
2,736.
1.575
4,311
Mills/kWh
1.30
0.55
1.85
1.40
0.58
1.98
1.40
0.51
1.91
1.08
0.58
1.66
1.00
0.57
1.57
$/ton. dry
26.01
44.12
29.63
27.99
46.47
31.68
28.03
40.84
30.59
21.52
46.63
26.54
26.06
59.99
32.84
a. Total annual revenue requirements consist of direct costs and
indirect costs; indirect costs are made up of overheads and capital
charges
127
-------
In comparison of costs per ton of ash» the costs for base cases 1
through 4, ranging from about 32 $/dry ton for base case 2 to about 27 $/dry
ton for base case 4, have the same proportional differences as the annual
revenue requirements because the same quantities of ash are involved.
Although base case 5 has the lowest annual revenue requirements, the cost per
ton of ash is almost 33 $/dry ton because of the smaller quantity involved,
the usual effect of economy of scale.
The major costs in annual revenue requirements are shown in Table 27 as
percentages of the total annual revenue requirements. As in capital
investment, basic differences exist between ponding and landfill disposal. In
the landfill cases the proportion of the costs for operating labor is four to
five times that of the ponding cases. This is due to the operating labor for
mobile equipment. Similarly, overheads that depend on operating labor are
twice as high, proportionately, for landfill as for ponding. On the other
hand, the proportion for total capital charges for landfill is only 60% of
that for ponding. The cost distribution of base case 3, temporary ponding
followed by landfill, is similar to the direct landfill cases. Maintenance
constitutes about 10% of the costs regardless of the disposal method.
Utilities, including diesel fuel, are also a small cost regardless of the
disposal method.
TABLE 27. MAJOR COST ELEMENTS IN
ANNUAL REVENUE REQUIREMENTS
Percentage of total
annual revenue requirements3
Base case: 12345
Cost Element
Labor 4 4 17 17 20
Process reagents - - - - 2
Utilities
Electricity 1 211-
Diesel fuel - - 4 3 3
Maintenance 10 10 9 12 11
Sampling and analysis 1 1111
Dredging - 4
Overheads 9 9 19 18 20
Capital charges 75 73 45 47 43
a. Rounded to nearest whole number, costs less than
0.5% omitted.
128
-------
MODULAR CAPITAL INVESTMENT AND ANNUAL REVENUE REQUIREMENTS
Ash disposal methods can be conveniently categorized by the types of
equipment and facilities used or by the types of functions employed. Most
methods employ combinations of diverse types of equipment and facilities that
can be readily identified as units in the operation. In the same manner most
methods employ combinations of discrete functions that can be similarly
identified. Such divisions are useful in economic analyses, both in
determining the relative importance of different equipment, facilities, and
functions in overall costs and in projecting conclusions drawn from specific
analyses to more general situations. Modular costs were developed in this
study for both equipment and facility and functional modules.
Modular Costs by Type of Equipment and Facility Area
The modular cost divisions by equipment type and facility area consist of
five areas: hoppers, process equipment, pipelines, mobile equipment, and
ponds and landfill. The hopper area includes only the bottom ash, economizer,
air heater, and ESP ash hoppers. These are shown separately from other
process equipment because they constitute so large a portion of process
equipment costs. The process equipment area comprises all other process
equipment such as the water supply system (including pond return lines), all
pumps (including ash pumps), air conveying systems, dewatering systems, and
storage silos. The pipeline area consists only of the slurry pipelines.
Mobile equipment comprises all trucks and earthmoving equipment. The disposal
site area comprises all costs associated with the disposal sites except mobile
equipment. Summaries of the modular capital investment and annual revenue
requirements for the five base cases are shown in Tables 28 and 29 and
Figure 22. Detailed data are shown in Tables B-l through B-10 in Appendix B.
Capital investment by type of equipment illustrates that different types
of equipment have very different total capital investments compared with
uninstalled equipment cost. Different types of equipment have very different
installation and indirect costs. For example, in proceeding from equipment
cost to total capital investment, hoppers increase three times in cost.
Mobile equipment costs increase only 14%.
Modular Capital Investment by Type of Equipment and Facility Area--
In the hopper category, capital investment remains essentially constant
regardless of the disposal method, changing only in base case 5 because of the
smaller ash quantity. Although hopper costs are not, in general, affected by
subsequent ash handling, a variety of factors could greatly affect their
costs. In this study ESP's with a single SCA were assumed for fly ash
collection. Different collection methods, ESP designs, SCA's, and different
design philosophies could affect hopper costs.
Process equipment varies from a minor to a major portion of capital
investment depending on the disposal method. In base case 1 process
equipment, consisting mainly of the fly ash pneumatic system and the water
supply systems, is a relatively minor cost element. In base case 2 these
costs are increased about one-third by inclusion of the water treatment
system. Base case 3 has the lowest process equipment capital investment,
although it constitutes a larger portion of the total capital investment. In
this case the ash transportation pumping requirements are reduced because the
129
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TABLE 28. MODULAR CAPITAL INVESTMENT BY
EQUIPMENT AND FACILITY AREAS
Equipment or facility area. 1982 $
Mobile
Hoppers Process Pipeline equipment Pond Landfill Total
Base Case 1
k$ 2,591 2,457 2,500 0 18,312 0 25,860
% 10 9 10 0 71 0
Base Case 2
k$ 2,591 3,619 2,500 0 18,312 0 27,022
% 10 13 9 0 68 0
Base Case 3
k$ 2,591 2,349 698 1,382 5,382 3,727 16,129
% 16 15 4 9 33 23
Base Case 4
k$ 2,591 6,385 141 780 0 4,856 14,753
% 18 43 1 5 0 33
Base Case 5
k$ 2,231 5,376 143 839 0 4,054 12,645
% 18 42 1 7 0 32
130
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TABLE 29. MODULAR ANNUAL REVENUE REQUIREMENTS BY
EQUIPMENT AND FACILITY AREAS
Equipment or facility area. 1984 $
Mobile
Hoppers Process Pipeline equipment Pond Landfill Total
Base Case 1 *
k$ 704 827 483 0 3,071 0 5,085
% 13.8 16.3 9.5 0 60.4 0
Base Case 2
k$ 704 1,142 483 0 3,108 0 5,437
% 12.9 21.0 8.9 0 57.2 0
Base Case 3
k$ 704 842 136 1,599 1,201 768 5,250
% 13.4 16.0 2.6 30.5 22.9 14.6
Base Case 4
k$ 704 1,657 31 1,198 0 965 4,555
% 15.4 36.4 0.7 26.3 0 21.2
Base Case 5
k$ 625 1,519 31 1,309 0 827 4,311
% 14.5 35.2 0.7 30.4 0 19.2
131
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OJ
ro
25
20
15
10
Ponds
Pi
Landfill
eline Mobile
equip.
Process
Hoppers
Base case: 1
234
CAPITAL INVESTMENT
Ponds
Landfill
Mobile equipment
Pipeline
23 45
ANNUAL REVENUE REQUIREMENTS
Figure 22. Modular costs by equipment and facility area.
-------
ponds are only one-fourth mile away. In base cases 4 and 5, direct landfill
disposal, process equipment is increased by inclusion of the bottom ash
dewatering system and fly ash silos. These roughly double process equipment
capital investment compared with the pond disposal cases.
Pipeline capital investment is essentially equivalent to hopper and
process equipment capital investment in base cases 1 and 2. In base case 3,
pipeline investment is reduced almost in proportion to the length reduction
from one mile to one-fourth mile. The short bottom ash transport line to the
dewatering bins in base cases 4 and 5 is not a significant factor in capital
investment.
Mobile equipment is a minor element of capital investment, constituting
only 5% and 7% of base cases 4 and 5 total capital investment. In terms of
capital investment dry trucking and placement is two-thirds less expensive
than wet sluicing over the one-mile distance.
In base cases 1 and 2 pond costs constitute two-thirds of the capital
investment. The effect of pond size is seen in,base case 3, which has 5-year
rather than 30-year ponds. A sixfold reduction in pond capacity is
accompanied by only a three-fold reduction in pond costs. In comparison,
landfill capital investment is about one-fourth that for ponds.
Modular Annual Revenue Requirements by Type of Equipment and Facility Area—
The cost distribution of annual revenue requirements is strongly
influenced by capital charges derived from the capital investment r»« The effect
of capital charges is variable depending on the type of equipment or facility,
as the comparison of base case 1 and base case 4 taken from Tables B-2 and B-8
illustrate for comparable pond and landfill disposal methods.
Annual revenue requirements - 1984 k$
Pipe- Mobile Land-
Hoppers Process line equipment Ponds fills Total
Base Case 1
Direct 202 317 72 - 237 - 828
Capital charges 381 361 368 - 2,692 - 3.801
Overheads 121 149 43 - 142 - 456
Total 704 827 483 3,071 5,085
Capital charges, % 54 44 76 88 75
Base Case 4
Direct 202 460 6 723 - 157 1,548
Capital charges 381 937 22 115 - 714 2,169
Overheads 121 260 _3_ 360 - 94 839
Total 704 1,657 31 1,198 965 4,555
Capital charges, % 54 57 71 10 74 48
133
-------
The annual revenue requirements for ponds, landfills and pipelines are
particularly affected. Capital charges account for almost nine-tenths of pond
annual revenue requirements and almost three-fourths of landfill and pipeline
annual revenue requirements. At the opposite extreme, capital charges
constitute only one-tenth of the mobile equipment annual revenue
requirements. As a result, there is a large difference between direct and
indirect cost ratios for the pond and the landfill disposal methods. For pond
disposal, capital charges account for three-fourths of the annual revenue
requirements; for landfill disposal, capital charges account for only one-
half.
In terms of direct costs, therefore, pond disposal is a low-cost disposal
method, costing only one-half as much as landfill disposal. This is achieved,
however, by a large capital expenditure for ponds, which increases the total
annual revenue requirements above those for landfill disposal.
In terms of equipment areas, annual revenue requirements for hoppers are
the same regardless of the disposal method employed, constituting about one-
seventh of the total for all five base cases. Process equipment annual
revenue requirements constitute about one-sixth of the total for pond
disposal. Water reuse, requiring treatment and return, increases process
equipment annual revenue requirements by one-third. Process equipment annual
revenue requirements for landfill disposal are more than one-third of the
total annual revenue requirements because of the additional dewatering,
storage, and loading operations required. Base case 3, temporary ponding and
landfill, has process equipment annual revenue requirements similar to those
for pond disposal because dewatering, storage, and loading costs are functions
of the mobile equipment and pond areas.
Pipeline area annual revenue requirements for base cases 1 and 2 are
relatively minor cost factors. In contrast, mobile equipment annual revenue
requirements are over twice as high and constitute about one-fourth of the
total annual revenue requirements for landfill disposal.
Pond annual revenue requirements are by far the largest cost element in
base cases 1 and 2. The predominance of capital charges in these costs has
been discussed. Direct costs for ponds consist largely of maintenance costs.
Water treatment costs are minimal, as shown by the small difference between
base case 1 and base case 2 pond area annual revenue requirements. The
influence of capital charges acts to decrease pond disposal area (pond plus
landfill) annual revenue requirements for base case 3. This occurs even
though there are substantial additional costs for landfill.
Landfill area annual revenue requirements are also dominated by capital
charges. These are, however, much lower than pond capital charges because of
the lower landfill construction costs. Landfill direct costs consist largely
of operating labor and maintenance.
Modular Costs by Process Area
The modular divisions by process area consist of four areas: collection,
transportation, disposal site, and water treatment and reuse. These four
areas are, in turn, subdivided into bottom as"h and fly ash areas. In cases
where the allocation of costs cannot be made on the basis of specific
134
-------
equipment functions, or flow rates, (water treatment for example) it is made
on the basis of ash quantities. Eighty percent of the costs are assigned to
fly ash and 20% to bottom ash in these cases. The equipment lists show the
modular equipment divisions upon which the cost divisions are based. They
also show the proration of costs for equipment common to both fly ash and
bottom ash.
The collection area consists of the ash hoppers, a portion of the water
supply systems, and the fly ash pneumatic systems including the vacuum
producers. The transportation area consists of air separators, a portion of
the water supply systems, ash pumps, the pipeline systems, trucks, storage
silos and moisturizers, the bottom ash dewatering bins, and removal of ash
from temporary ponds. The disposal area consists of ponds and landfills,
including all mobile equipment except that used to load and haul ash. The
water treatment and recycle area consists of the treatment systems, pumps and
return lines, and the bottom ash water systems. Modular costs by process area
for base cases 1 through 5 are summarized in Tables 30 and 31. Detailed data
are shown in Tables B-ll through B-20 in Appendix B.
Modular Capital Investment by Process Area--
Collection area capital investments do not differ greatly. Most of the
direct costs are associated with hoppers and the fly ash collection systems
that are similar for all processes. The collection area capital investment
for base case 4 is higher because of the separation equipment and mechanical
exhauster used for dry fly ash collection. These costs are also included in
the base case 5 collection area but the total collection area capital
investment is reduced because of the smaller quantity of ash.
Depending on the method of disposal, transportation capital investment
consists largely of pipeline, mobile equipment, and storage and dewatering
equipment costs. In base cases 1 and 2 the mile-long pipelines are the major
cost. The base case 3 capital investment is lower because of the reduced
costs for the quarter-mile-long pipelines. This reduction is greater than the
additional capital investment for trucks and loaders. In base cases 4 and 5,
the bottom ash dewatering bins and fly ash silos constitute the major
expense.
Pond and landfill construction costs are the only substantial disposal
area capital investments. Mobile equipment capital investment is only about
one-tenth of disposal site capital investment for landfill disposal. Because
of the large capital investment for pond construction, base cases 1 and 2 have
disposal site capital investments more than three times larger than base
case 4 and about two times those of base case 3. In all five base cases
disposal site capital investment is the highest cost area, ranging from about
70% of the total for direct ponding to 36% of the total for direct landfill
disposal.
The capital investment for water treatment and recycle is a relatively
small component of the total capital investment. For base case 1, in which
the sluice water is simply treated for pH control before discharge, the
capital investment is less than 0.3 $/kW. This is increased to 2.6 $/kW,
5% of the total capital investment, by additional treatment to control scaling
and recycle. About two-thirds of this increase is the one-mile-long return
water pipeline. In base case 3, with both pond and landfill effluent water
135
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TABLE 30. MODULAR CAPITAL INVESTMENT BY PROCESS AREA
1982 k$
Collection Transportation
Base Case 1
Fly ash
Bottom ash
Total
7
/o
Base Case 2
Fly ash
Bottom ash
Total
%
Base Case 3
Fly ash
Bottom ash
Total
%
Base Case 4
Fly ash
Bottom ash
Total
%
Base Case 5
Fly ash
Bottom ash
Total
%
2,337
1,524
3,861
15
2,337
1,524'
3,861
14
2,340
1.481
3,821
23
2,734
1,524
4,258
29
2,272
1,304
3,576
28
1,791
1.765
3,556
13
1,791
1,765
3,556
13
1,452
1,095
2,547
16
2,582
1,824
4,406
30
2,204
1,610
3,814
30
Disposal site
14,648
3,662
18,310
71
14,648
3,662
18,310
68
7,620
1,868
9,488
59
4,231
1,064
5,295
36
3,609
903
4,512
36
Water
treatment
and recycle Total
105
28
133
1
1,025
270
1,295
5
216
57
273
2
105
689
794
5
105
638
743
6
18,891
6,979
25,860
100
19,801
7,221
27,022
100
11,628
4,501
16,129
100
9,652
5,101
14,753
100
8,190
4.455
12,645
100
136
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TABLE 31. MODULAR ANNUAL REVENUE REQUIREMENTS BY PROCESS AREA
1984 k$
Base Case 1
Fly ash
Bottom ash
Total
%
Base Case 2
Fly ash
Bottom ash
Total
7
/o
Base Case 3
Fly ash
Bottom ash
Total
7
to
Base Case 4
Fly ash
Bottom ash
Total
7
10
Base Case 5
Fly ash
Bottom ash
Total
%
Collection
681
423
1,105
22
681
423
1,105
20
680
409
1,089
21
751
420
1,171
26
647
365
1,012
24
Transportation
385
442
827
16
380
440
821
15
1,219
474
1,692
32
798
535
1,333
29
747
494
1,241
29
Disposal site
2,451
615
3,065
60
2,451
615
3,065
57
1,837
456
2,294
44
1,348
350
1,698
37
1,285
324
1,609
37
Water
treatment
and recycle
54
34
88
2
330
116
446
8
112
62
174
3
57
296
354
8
57
387
444
10
Total
3,571
1,514
5,085
100
3,842
1,595
5,437
100
3,848
1,402
5,250
100
2,954
1,600
4,555
100
2,736
1,575
4,311
100
137
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treatments, capital investment is only 0.5 $/kW. In base cases 4 and 5 most
of the capital investment for water treatment and recycle is for bottom ash
sluice water treatment and recycle.
Modular Annual Revenue Requirements by Process Area--
Capital charges have an effect on the modular annual revenue requirements
by process area similar to, though less extensive than, their effect on
modular annual revenue requirements by type of equipment. As shown below for
base cases 1 and 4 taken from Tables B-12 and B-18, the capital charge
component of the modular annual revenue requirements varies from 88% to 23%.
Water
Trans- Disposal treatment
Collection portation site and recycle Total
Base Case 1
Direct 350 201 234 43 829
Capital charges 568 523 2,692 20 3,801
Overheads 187 104 140 26. 456
Total 1,105 827 3,065 88 5,085
Capital charges, % 51 63 88 23 75
Base Case 4
Direct 348 444 607 149 1,548
Capital charges 626 648 778 117 2,169
Overheads 197 241 312 89 839
Total 1,171 1,333 1,698 354 4,555
Capital charges, % 53 49 46 33 48
Costs for the pond disposal site are largely composed of capital charges
because few operating costs are associated with pond disposal. In contrast,
capital charges for the landfill disposal site are only 46% of the total
annual revenue requirements. This results both from the larger operating
costs and from the lower capital investment. The capital charge component of
annual revenue requirements for the other process areas are less extreme and
differ less between the two disposal processes than they do for the modular
categorization by type of equipment. The categorization by process area
combines various types of equipment and tends to reduce the difference in cost
distributions.
In terms of process area costs the annual revenue requirements for
collection remain essentially constant regardless of the disposal method. The
equipment is essentially the same in all cases with the exception of the
vacuum producer and pumps. Base case 3 is slightly lower than base cases 1
and 2 because of lower pumping costs related to the shorter distance to the
ponds. Base cases 4 and 5 have higher fly ash collection costs because of
higher capital charges related to the particulate collectors and mechanical
vacuum pump.
138
-------
Transportation annual revenue requirements are higher for trucking to a
landfill (base case 4) than they are for sluicing to a pond (base cases 1
and 2). Maintenance, labor, and to a lesser extent diesel fuel, are important
cost elements in trucking. Maintenance costs are lower for sluicing than for
trucking, electricity costs are lower than diesel fuel costs, and labor costs
are minor. Transportation annual revenue requirements for base case 3, which
uses both sluicing and trucking, are increased by costs associated with
removing the ash from the ponds, particularly dredging costs. There is no
large difference in transportation annual revenue requirements for dry ash,
represented by base case 5, and moist ash, represented by base case 4.
Disposal site annual revenue requirements are the largest cost element in
all of the disposal methods. Most of the costs in the ponding methods (base
cases 1 and 2) result from the capital charges. Maintenance is the only
significant direct cost. Capital charges are less dominant in landfill annual
revenue requirements (base case 4) and there are substantial direct costs in
labor, maintenance, and diesel fuel. Base case 3 has disposal site costs
intermediate between base cases 1 and 2 and base case 4. This relationship is
a result of the smaller capital charges for the smaller ponds. Labor costs
for base case 3 are also lower than for base case 4 because a common landfill
is used.
Water treatment and recycle is not an important cost element in any of
the disposal methods. Sampling and analyses, and water recycle equipment
capital charges and operation are the largest cost elements. Thus base
case 2, with a mile-long return system, and base cases 4 and 5, with bottom
ash water recirculation systems, have higher annual revenue requirements in
this area. Base case 5 also has a substantial direct cost for sulfuric acid
because of the high-calcium ash.
CASE VARIATIONS
Case variations for the five base cases were calculated to evaluate the
effect of different conditions on costs. The conditions studied were trucking
distance to the disposal site, ash collection rate, land cost, and percentage
of ash utilization.
Trucking Distance to Disposal Site
As shown in Figure 23, trucking distance has a relatively minor effect on
total capital investment. Total capital investment increases at 20,300,
13,600, and 9,200 $/mile for base cases 3 through 5 respectively. This
means, for example, that an increase in trucking distance from 1 to 10 miles
in base case 4 increases the total capital investment by $122,000, which is
41% of the base case capital for trucking but only 1% of capital investment
for the total ash disposal system. These results are derived from the number
and size of trucks required, assuming an average highway speed of 30 mph, and
base case cycle times of 36, 30, and 52 minutes for base cases 3 through 5
respectively. The differences among the cases reflect a lower moisture
content of the fly ash for base cases 4 and 5, and a lower ash quantity in
base case 5.
139
-------
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CAPITAL INVESTMENT, M$
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Annual revenue requirements are affected by the added direct operating
costs of the vehicles such as labor, fuel, and maintenance. Additional
charges are incurred from higher capital charges and service overheads. Total
annual revenue requirements increase constantly at rates of 23,200, 16,500,
and 10,400 $/mile for base cases 3 through 5 respectively. Thus, an increase
in trucking distance from 1 to 10 miles in base case 4 adds $149,000 to annual
revenue requirements, which is a 40% increase for trucking but a 3% increase
relative to total annual revenue requirements. As in total capital
investment, these amounts take into account the different moisture contents
and ash tonnages of the base cases.
Ash Collection Rate
Ash collection rate may vary with such factors as the load on the power
plant, power plant heat rate, heating value of the coal, ash content of the
coal, and ash collection efficiency. To evaluate the effect of ash rate on
costs, capital investment and annual revenue requirements were determined at
fly ash plus bottom ash collection rates totaling 47,730, 62,400, and
77,070 Ib/hr. The low level is that of base case 5; the intermediate level is
the collection rate for base cases 1 through 4. Figure 24 shows the results
of these evaluations. It shows that both capital investment and annual
revenue requirements have slightly curvilinear relationships with ash rate.
The degree of curvature can be expressed as the cost-to-size exponent
connecting costs for successive pairs of ash rates. The exponents are shown
below for ash disposal cost relative to ash disposal rate.
Base case
47,730 to
62.400 Ib/hr
62,400 to
77.070 Ib/hr
Capital Investment
1
2
3
4
5
0.75
0.75
0.73
0.68
0.66
0.75
0.76
0.70
0.67
0.70
Annual Revenue Requirements
1
2
3
4
5
0.68
0.68
0.68
0.63
0.64
0.69
0.68
0.67
0.64
0.65
The exponents represent cost relationships in the expression
cost 1 = cost 2 (rate I/rate 2)exP. The exponents for capital investment
for base cases 1 and 2, using pond disposal, are 0.75, while those for base
cases 4 and 5, using landfill disposal, are lower at 0.68. Base case 3 has
both ponds and landfill and its exponents fall between the other pairs of
cases. For annual revenue requirements, the exponents for base cases 1, 2,
and 3 are virtually the same at 0.68, while base cases 4 and 5 have lower
141
-------
ANNUAL REVENUE REQUIREMENTS, M$
CAPITAL INVESTMENT, M$
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exponents of 0.64. For both capital investment and annual revenue
requirements, the lower exponents for cases with landfills mean that landfills
have slightly greater economy of scale than do ponds.
Ponds and landfills, the dominant cost items in ash disposal, have cost
variations with ash collection rate according to the size of the pond or
landfill, and according to the number of ponds or landfills used. Figure 25
shows both types of variations. The ash collection rate for the life of the
project translates to pond or landfill volume. For two ponds, as in base
cases 1, 2, and 3 the cost-to-size exponent is 0.69 and for two landfills
(base cases 4 and 5) it is 0.66. These exponents are for direct investment
excluding the cost of mobile equipment for the site. The slightly lower
exponent for landfills results from the previously noted greater economy of
scale for landfills. Figure 25 also shows that the single landfill for base
case 3 is only 87% as costly as the two landfills for base cases 4 and 5 at
the same volume. This feature emphasizes the site-specific dependence of the
disposal site configuration.
Land Cost
The effects of land cost and annual revenue requirements are shown in
Figure 26 for land costs of $1,000, $10,000, and $15,000 per acre, as compared
with the base case cost of $5,000. Land cost effects are linear and the
overall cost effects are moderate. For example, increasing the cost of land
from $5,000 per acre to $15,000 per acre increases base case 1 capital
investment by 15% and it increases annual revenue requirements by 11%.
Ash Utilization
The effects of utilizing 25% and 50% of the ash are shown in Figure 27.
Utilized ash is assumed to be removed from ponds in base cases 1 to 3 and from
the fly ash silos and dewatering bins in base cases 4 and 5 at no cost to the
utility. The main cost effects are in reduced trucking requirements and
reduced disposal site requirements. The percentage changes in capital
investment and annual revenue requirements are shown below. Utilization
results in larger savings in base cases 1 and 2 than in base cases 3, 4,
and 5. This difference is due to the much larger cost of ponds compared with
landfills.
143
-------
DIRECT INVESTMENT, M$
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PERCENTAGE OF ASH UTILIZED
45
60
Figure 27. Effect of ash utilization on costs, base cases 1 through 5.
146
-------
Annual
Percentage Capital investment revenue requirements
utilization percentage decrease percentage decrease
Base case 1: 25 14 12
50 30 26
Base case 2: 25 14 11
50 29 25
Base case 3: 25 10 9
50 17 18
Base case 4: 25 9 9
50 16 18
Base case 5: 25 11 10
50 16 18
147
-------
COMPARISON WITH TVA ASH DISPOSAL COSTS
Direct comparisons of conceptual design costs with actual costs of
operating systems are frequently difficult to make because of disparate design
and economic bases. This has been most apparent in comparisons of FGD costs
from different sources (93, 94) where the difficulties are compounded by the
relative immaturity of the technology. Ash collection, and to a lesser extent
disposal, may be regarded as a more developed technology than FGD.
Nevertheless, many of the same difficulties exist. In particular, site-
specific conditions of actual installations such as size, ash production
rates, and environmental constraints must usually be accounted for.
Accounting methods may also differ, as well as the degree to which costs are
identified and isolated (particularly operating labor and maintenance) . As
has been discussed, ash transportation distance, the configuration of the
transportation path, and the disposal site itself are highly site specific.
It is also necessary, of course, to use the same cost basis in comparing
conceptual design costs (usually projected into the future) with actual costs
(usually for a period one or more years in the past).
It is possible, however, to compare certain aspects of the costs
developed in this study with actual ash disposal costs at TVA coal-fired power
plants. There are 12 coal-fired power plants in the TVA system, all of which
presently dispose of ash by sluicing to permanent ponds with once-through
condenser cooling water from a river, similar to the base case 1 process of
this study. The pond effluents have been described in a previous study (74).
Eight of the TVA plants were selected for cost comparisons with the base
case 1 conceptual design. The others have cyclone or wet-bottom furnaces or
have disposal site expansion costs that cannot be differentiated from the
usual operating costs. The eight plants selected have dry-bottom pulverized-
coal-fired furnaces burning bituminous coal. They were constructed in the
period 1951 to 1973. The average station capacity is 1,600 MW and the average
unit capacity is 260 MW. In 1978 the average yearly ash production was
563,000 tons per plant, (in comparison, base case 1 represents a 500-MW power
unit producing 171,600 tons of ash per year.) The bottom ash is typically
sluiced from the hoppers through clinker grinders and pumped through steel
pipelines with centrifugal pumps. Fly ash is typically removed from the flue
gas with ESP's or mechanical collectors and collected with vacuum systems
using water ejectors. It is sluiced to the ponds through steel pipes, either
separately or combined with the bottom ash. The onsite ponds differ in size,
configuration, and construction technique and are situated from a few hundred
feet to over one mile from the power plants.
Comparisons of base case 1 direct capital investment can be made with the
installed costs of ash disposal equipment for two power units at two TVA
plants constructed in 1963 and 1965. Indirect costs cannot be readily
compared because of differences in accounting and financial practices.
148
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Computed by the same method, the total capital investments would have the same
relationships as the direct costs, however. Similarly, the base case 1
operating and maintenance costs are compared with the TVA operating and
maintenance costs. In this comparison costs for all eight of the TVA plants
are used. The TVA costs vary among plants because of site-specific conditions
so the average of the costs at the eight plants is used as the basis of
comparison.
Several adjustments are made in the cost data to provide the same basis
of comparison. Since TVA power plants were constructed at different times,
their equipment costs are projected to 1982 for comparison with the base
case 1 capital costs. The TVA costs are also adjusted for size, pipeline
length, and other factors as discussed below. Pond site costs are excluded
from the equipment cost comparison because of the differences in design
concepts and the highly variable site-specific nature of the TVA ponds. The
common time basis for operating and maintenance costs was obtained by
adjusting the TVA 1978 average costs to 1984 for comparison with the base
case 1 projected 1984 operating and maintenance costs.
EQUIPMENT COST COMPARISONS
The costs of installed ash disposal equipment at the two TVA power plants
used and the nature of the adjustments needed for comparison with base case 1
are shown in Tables 32 and 33. The TVA costs represent materials,
installation labor, and supporting equipment. The ESP hopper costs are
excluded from the base case 1 costs because they are not differentiated in the
TVA ESP costs. The TVA cost adjustments consist of: (1) an increase in the
bottom ash hopper capacity from 8 to 12 hours, (2) an adjustment in the
pipelines to a one-mile length, basalt lining, and spare provisions, (3) a
size factor based on a cost-to-size exponent of 0.8, and (4) an inflation
factor.
Results of the adjusted ash disposal investment costs for plants A and B
are summarized and compared with the conceptual-design costs in Table 34. For
the total ash disposal system, the conceptual-design cost of base case 1 is
10% higher than that of plant A and 5% higher that that of plant B. Relative
to both plants, the base case costs are high for bottom ash disposal and
slightly low for fly ash disposal. Incomplete allocations between the bottom
ash and fly ash systems could account for this.
OPERATING AND MAINTENANCE COST COMPARISON
The operating and maintenance costs (excluding electricity) for ash
disposal from 1970 to 1978 at the eight TVA plants are shown in Figure 28.
The 1978 average is projected to 1984 using the cost indexes in the premises.
The base case 1 operating and maintenance cost is also shown using the 1984
cost developed in this study and as an adjusted cost based on an ash
production rate equivalent to the TVA rate.
The TVA costs comprise the operating labor and the maintenance labor and
materials for removal of ash from the hoppers, sluicing to the ponds, pond
149
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TABLE 32. INSTALLED COST OF ASH DISPOSAL SYSTEMS AT TVA POWER PLANT A
TVA accounted
cost, k$ (1963)
Adjustments to meet
base-case conditions
Adjusted cost,
k$ (1982)
Bottom Ash Disposal System
Collecting and Handling System
Ash hopper assembly (8-hour storage 29Q 2
capacity, clinker grinders, etc.) and
associated handling equipment (pumps,
motors, piping, valves» and control
equipment)
Disposal Piping
1,500-foot-long slurry pipelines (carbon 58.0
steel, extra strong) with fittings, and
supports
Trench under powerhouse for bottom ash 71.8
and fly ash piping
Addit ion lor 12-hour storage
capacity on hopper cost of k$ 139.2 53.3
Unit size and inflation factor^ 2.713
Bottom ash allocation of
pipeline cost, 20% of k$ 58.0 11.6
Pipeline extension to 1 mile 29.2
Addition for basalt-lined quality 122.9
Share of 1-mile, carbon-steel
spare pipeline 16.1
Bottom ash allocation of trench
cost, 20% of k$ 71.8 14.4
Unit size and inflation factor3 2.713
932
527
Sluice Water Supply System
Pumps, motors, piping, fittings, and
valves for bottom ash and fly ash systems
Total, bottom ash disposal system
98.6 Bottom ash allocation, 20% 19.7
Unit size and inflation factor 2.713
54
1,513
Fly Ash Disposal System
Handling System
Vacuum pneumatic system of valves, piping,
and control equipment for handling ash from
hoppers on air preheaters, primary air
heater, gas outlet ducts and ESP, and
delivery to combined ash slurry pipelines;
excludes ESP and hoppers
Disposal Piping
Accounted in cost of bottom ash disposal
piping and trench
Sluice Water Supply System
Accounted in cost of bottom ash sluice
water supply system
Total, fly ash disposal system
Total, ash disposal systems
123.6
Hopper insulation accounted with
ESP which is excluded from ash
disposal comparison 44.9
Unit size and inflation factor
Fly ash allocation of pipe-
line cost, 80% of k$ 58.0
Pipeline extension to 1 mile
Share of 1-mile carbon-steel
spare pipeline
Fly ash allocation of trench
cost, 80% of k$ 71.8
Unit size and inflation factor
Fly ash allocation,
k$ 98.6
of
Unit size and inflation factor
2.713
46.4
116.9
64.4
57.4
2,713
78.9
2.713
457
642.2
773
214
1,444
2,957
Unit size factor of 0.927 and inflation factor of 2.927.
150
iVifej^pSllsSfe-Si^ir
-------
TABLE 33. INSTALLED COST OF ASH DISPOSAL SYSTEMS AT TVA POWER PLANT B
TVA accounted
cost, k$ (1965)
Adjustments to meet
base-case conditions
Adjusted cost,
k$ (1982)
Bottom_Ash Disposal System
Collecting and Handling System
Ash hopper assembly (50-ton capacity,
clinker grinders, etc.) and associated
handling equipment (pumps, motors, piping,
valves, and control equipment)
Disposal Piping
3,240-foot-long slurry pipelines (carbon
steel, extra strong) with fittings, and
supports
Trench under powerhouse for bottom ash
and fly ash piping
Sluice Water Supply System
Pumps, motors, piping, fittings, and
valves for bottom ash and fly ash systems
Total, bottom ash disposal system
244.8
159.7
312.0
Addition for 12-hour storage
capacity on hopper cost of k$ 214.4 82.1
Unit size and inflation factor3 1.722
Bottom ash allocation of
pipeline cost, 20% of k$ 244.8 49.0
Pipeline extension to 1 mile 30.8
Addition for basalt-lined
quality 240.2
Bottom ash allocation of trench
cost, 20% of k$ 159.7 31.9
Unit size and inflation factor3 1.722
Bottom ash allocation, 20% 62.4
Unit size and inflation factor3 1.722
b99
606
107
1,412
Fly Ash Disposal System
Handling System
Vacuum pneumatic system of valves,
piping, and control equipment
for handling ash from econo-
mizers and ESP, and delivery to combined
ash slurry pipelines; excludes ESP and
hoppers
Disposal Piping
Accounted in cost of bottom ash dis-
posal piping
Sluice Water Supply System
Accounted in cost of bottom ash sluice
water supply system
Total, fly ash disposal system
Total, ash disposal systems
175.3
1,215.7
Hopper insulation accounted with
ESP which is excluded from ash
disposal comparison 113.2
Unit size and inflation factor3 1.722
Fly ash allocation of pipe-
line cost, 80% of k$ 244.8 195.8
Pipeline extension to 1 mile 123.3
Fly ash allocation of trench
cost, 80% of k$ 159.7 128.8
Unit size and inflation factor3 1.722
Fly ash allocation, 80% of k$ 312.0 249.6
Unit size and inflation factor2 1.722
497
771
430
1,698
3,110
a. Unit size factor of 0.598 and inflation factor of 2.877.
151
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TABLE 34. COMPARISON OF BASE CASE 1 WITH TVA INSTALLED COSTS OF ASH DISPOSAL SYSTEMS
Bottom ash disposal system Fly ash disposal system Total ash disposal systems
Base case Base case Base case
k$ (1982) difference, % k$ (1982) difference, % k$ (1982) difference, %
Base
TVA
TVA
case 1
plant Ab
plant Bc
1,772
1,513
1,412
l,482a
+17 1,444 +3
+25 1,698 -13
3,254
2,957 +10
3,110 + 5
a.
b.
c.
Excluding
Adjusted
Adjusted
fly ash
as shown
as s hown
hoppers.
in Table 32.
in Table 33.
-------
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(D "-•
ASH DISPOSAL OPERATING AND MAINTENANCE COSTS, $/ton
00
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-------
maintenance, and treatment and control of the discharge water. For each plant,
the costs are expressed as annual dollars per ton of ash. In 1978 the average
TVA ash production rate per plant was 562,500 tons of ash, producing an
average operating and maintenance cost of $1.95 per ton. Projected to 1984
the cost is $3.07 per ton.
Base case 1 operating and maintenance costs are obtained, on a
comparative basis, from annual revenue requirements as shown in Table 35.
Here, the total direct costs comprise only $4.82/ton of ash of the total
annual revenue requirements of $29.63/ton of ash. This perspective
illustrates that plant-based direct costs are only 16% of the total amount.
Base case 1 operating and maintenance costs, excluding electricity, are
$766,800, or $4.47 per ton in 1984 dollars based on 171,600 tons per year of
ash. This cost is based on an ash production rate that is 31% of the TVA
average rate. Comparison of the ash collection and slurry pipeline systems
indicates that 0.79 is an appropriate size correction factor (not an
exponent). Applying this correction, the base case 1 costs become $3.53 per
ton in 1984 dollars.
Design differences other than plant size and ash tonnage lead to small or
offsetting differences in operation and maintenance cost. For example, a
reduction in length of slurry pipeline from 1 mile to 1/2 mile would lower
pipeline maintenance by $0.20 per ton of ash but the combination of greater
ash dilution and higher slurry velocities in the TVA pipelines appears to
increase the pipeline size, and hence maintenance cost, by a similar amount.
At $3.53 per ton of ash, the base case 1 cost for operation and
maintenance is 15% higher than the 1984 TVA cost of $3.08 per ton of ash. A
part of this difference is due to the provisions in base case 1 for additional
environmental protection.
154
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TABLE 35. BASE CASE 1 OPERATING AND MAINTENANCE COSTS
COMPARATIVE BASIS
Direct Costs
Conversion costs
Operating labor
Process reagents
Utilities
Water
Electricity
Maintenance
Process
Pond
Sampling and analysis
Total direct costs
Total direct costs
excluding electricity
Annual revenue
requirements,
1984 $
k$
$/ton
206.3
3.6
6.9
61.1
287.0
221.0
42.0
827.9 4.82
766.8 4.47
Operations and
maintenance,
comparative
basis,
1984 $
$/ton
3.53
Indirect Costs
Plant and administrative
overheads
Levelized capital charges
Total indirect costs
Total first-year annual
revenue requirements
456.0
3,801.4
4,257.4 24.81
5,085.3 29.63
Basis: Ash rate, 171,600 tons/year. Plant cost indexes,
218.8 in 1978, 344.9 in 1984.
155
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COMPARISONS AMONG ASH DISPOSAL STUDIES
Results of this study can be compared with those of published reports
only to the extent that comparability exists among the disposal systems
evaluated and among the methods used. Rarely are comparisons of actual cost
possible for total ash disposal systems because of the varying design and
economic premises found in this highly site-specific subject.
The disposal rate and site capacity are determined by coal properties
and boiler features, operating schedules of the boiler and ash removal
systems, and duration of plant life. Choice of ash handling and
transportation equipment is influenced by factors such as the nature of the
ash, the altitude of the site, the transportation distance and terrain, and by
the type of disposal site. The largest contributor to ash disposal costs, the
disposal site, reflects the characteristics of the ash, terrain, land
availability, soil conditions, and environmental constraints.
Typical combinations of these variables which serve as design premises
for three separate studies are shown in Table 36. Even without the
intricacies of pond and landfill designs, the listing shows the breadth of
conditions encountered. Most impressive are the lifetime tonnages of ash»
which range from 2.8 to 61 million tons, and the lifetime volumes of ash,
which range from 2.6 to 56 million yd^ for landfill disposal. These
divergent amounts cannot safely be reduced to a common basis by the
application of cost-to-size scaling factors unless the factors are accurately
known for the particular designs.
The economic premises also differ among the studies, and when inflation,
discounting, and levelization factors are used, the results are greatly
influenced by the factors chosen. It is extremely difficult to compare ash
disposal costs which are based on different premises and are expressed on
different bases such as (1) first-year operating costs, (2) levelized
operating costs, (3) life-of-project costs, and (4) present worth life-of-
project costs. The purposes, methodologies, and expression of results among
these studies explain why they can validly differ in the type of ash disposal
systems used and in qualitative results.
This study includes all areas of ash handling and disposal from
collection hoppers through disposal site and effluent treatment. Its disposal
site designs are based on the RCRA nonhazardous guidelines. It emphasizes
comparisons among modules of ash collection, handling, and disposal, including
wet transportation to ponds and dry transportation to landfills, but its scope
does not include all forms of ash transportation or variations in site
topography. The capital investments are based on full and nondiscounted
156
as^ss;
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TABLE 36. COMPARISON OF PREMISES AND COSTS AMONG ASH DISPOSAL STUDIES
Design Premises
Plant location
Plant life, yr
Boiler type
Generating capacity, MW
Plant heat rate, Btu/kWh
Capacity factor, %, hourly
Capacity factor, %, yearly
Coal type
Coal heating value, Btu/lb
Coal ash, as fired. %
Ash to fly ash, 1
Coal sulfur, as fired, %
Sulfur to ash, I
Ash utilization
Ash to disposal, tons/hr
Ash to disposal, tons/yr
Ash to disposal, tons/life
Ash to disposal, tons/MWyr
Type of disposal site detailed:
Solids in slurry, %
Slurry water recycle
Distance to disposal site, mile
Terrain
Ash bulk density, Ib/ft3
Ash volume, Myd3
Land area, acre
Depth of fill, ft
Liner
Groundwater monitoring wells
Stormwater treatment
Security fence
Closure, revegetation
Economic Premises
Construction year
Startup year
Areas costed
Capitalization of site
This study
(EPA)
North Central U.S.
30
P-C dry bottom
500
9,500
100
63
Bituminous
11,700
15.1
80
3.36
8
0
31
171,000
5,120,000
0.062
Pond Landfill
7.7
No
1 1
Level Level
55 90
6.9 4.2
390 142
14 or 17 20 to 80
Clay Clay
4 4
Yes Yes
Yes Yes
Yes Yes
1982
1984
Hoppers, collection,
transportation, disposal
100%
Bahor-Ogle
(EPA)
Southeastern U.S.
35
P-C dry bottom
2,600
10,000
80
80
Subbituminous
10,500
20
80
-
-
0
198
1,735,000
60,736,000
0.095
Pond Landfill
10
Yes
1 1
Narrow Narrow
valley valley
43 83
104 56
639 460
200
Synthetic Synthetic
None None
No No
No No
Yes Yes
1980
Collection, transpor-
tation, disposal
100%
GAI Consultants
(EPRI)
Midwestern U.S.
30
-
500
9,000
70 1st year
48.5 average
10,500
12.8
80
-
-
All bottom ash
94,600
2,840,000
0.045
Pond Landfill
5
Yes
1 i
Level Level
60 80
3.5 2.6
107 40
25 50
Yes Yes
1979
1980
Transportation,
disposal
100% 1/30
construction
Capitalization of closure,
revegetation
Land cost, $/acre
100%
5,000
1,500
At
present
worth
5,000
Final Costs
Total capital investment, k$ 25,860
Total system cost, k$
Present worth cost, k$
First-year annual revenue
requirements, k$ 5,085
Levelized annual revenue
requirements, k$ 6,223
First-year annual revenue
requirements, $/ton dry ash 29.63
Levelized annual revenue
requirements, $/ton dry ash 36.26
14,750
4,555
6,669
26.54
38.86
1.083,000
133,000
1,499,000
168,000
7,900
2.260
23.86
522
925
9.78
157
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capitalization of the life-of-project disposal sites and its operating and
maintenance costs are given on first-year and levelized bases. Detailed costs
are shown in each base case.
A recent study of wet versus dry ash disposal systems by Bahor and
Ogle (95) stresses disposal sites. It does not include collection hoppers,
uses an average cost for ash collection, and shows results for four methods of
transportation and four profiles of valley sites, each with and without
liners. Site designs follow implied State codes somewhat less restrictive
than RCRA requirements. The derivation of results is shown for only two
specific cases but end results are tabulated for 280 combinations of plant
capacity, transportation, site, and liner. The capital investment and
operating-maintenance costs are presented in two forms, present worth and
total system cost. Present worth is the initial capital investment plus the
present worth of inflated and discounted operating-maintenance costs for the
life of the project. Total system cost is a weighted cost of capital plus
operating-maintenance costs inflated during the life of the project. An 11%
discount rate and an 8.5% inflation rate is used, compared with 10% and 6% for
this study.
The cost estimating section of the GAI EPRI study (75) emphasizes
economic methodology, with graphical and computational derivation of the
principal variants in ash disposal. However, illustrative economics are
provided for a pond and a landfill case utilizing site costs from a prior
sludge disposal study. Capital investment and annual revenue requirements are
based on EPRI premises (90). Two effects of time are taken into account.
Since the cost of pond closure and revegetation occurs at the end of the
project, its initial capitalization is expressed at present worth. Also,
since the landfill is built over the life of the project, its initial
capitalization is taken at 1/30 of its total cost. These conventions reduce
the pond and landfill capital investments proportionately, as compared with
100% capitalization in the current study.
The preceding illustrations show that the disposal systems and their
economic evaluation vary widely from study to study and in most cases
comparability of specific cost results can only be established by
recalculation of the results. On the other hand, a report may have
qualitative conclusions based on comparability within the study and such
conclusions are subject to comparison between reports. Such a comparison can
be made between this study and the stated conclusions of Bahor and Ogle. In
this 1981 economic analysis of pond and landfill ash disposal systems, Bahor
and Ogle examined different types of disposal sites and concluded that site
topography was the primary influence on the economic selection of an ash
disposal system. Partly because of that study, the present conceptual design
assumes level disposal sites and does not address topography.
Bahor and Ogle state that the method of economic analysis is not a
primary factor in selection of an ash disposal system, that is, in deter-
mining a least-cost option. This assumes that the method is compatible with
the actual economics of the installation and operation of the system, of
course, and pertains only to comparisons within the same economic method. As
discussed above, qualitative comparisons of economic results derived using
158
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different methods cannot normally be made without adjustments frequently of
such a nature as to destroy the integrity of the adjusted results. In
contrast, qualitative results should be comparable, and in many cases
synergetic. providing in the comparison conclusions unattainable from the
individual studies.
In the present study landfill disposal has lower capital investment and
annual revenue requirements than pond disposal. Pond construction costs,
based on a level site requiring a designed pond with wholly enclosing dikes,
are the determinant factor in the cost relationships for both capital
investment and (as capital charges) for annual revenue requirements. Although
not addressed in quantitative terms because of its site-specific nature, the
use of natural landforms to reduce dike requirements would have a major effect
on cost relationships. Bahor and Ogle address this situation in greater
detail, providing quantitative data to support the conclusion. In general,
landfill disposal is the least cost alternative for flat areas whereas pond
disposal is the least cost alternative for valley disposal. In the GAI study,
which assumes a level site, this conclusion is supported by an even greater
difference in costs, due in large part to the smaller ash quantities and
relatively lower landfill construction costs. Bahor and Ogle use generalized
in-plant handling costs (95, p. 68) which differ considerably between wet and
dry systems. The difference is sufficient in some cases to influence the
relationship of overall pond and landfill disposal costs. In this study ash
collection and handling costs are subordinate to disposal site costs
but constitute an important element in overall costs. Different systems are
defined in detail. Both studies thus provide insight into the overall
relationship of the various ash collection and disposal costs. These
relationships are not specifically addressed in the GAI study.
Overall, comparison of these studies reveals variations in the disposal
systems used, in the economic structure of the evaluations, and in the focus
of purpose that is in many cases complementary. The conclusions are, however,
in general agreement.
159
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CONCLUSIONS
The most common current method of utility ash disposal is sluicing to a
permanent pond with no water recycle. The capital investment for this method
of disposal for a 500-MW power unit burning coal with 15.1% ash with a pond
one mile away is 52 $/kW (1982$). Annual revenue requirements for ash
disposal for the same plant, operating 5,500 hr/yr, are 1.85 mills/kWh
(1984$). Reuse of sluicing water, including treatment to prevent scaling,
increases the capital investment by about 2 $/kW and annual revenue
requirements by about 0.13 mill/kWh.
Landfill disposal (consisting of dewatering the bottom ash and dry
collection of the fly ash followed by trucking of the ash one mile to a
managed landfill) has a capital investment of 30 $/kW and annual revenue
requirements of 1.66 mills/kWh for the same power unit conditions, which is
less costly than ponding.
A combination process using temporary ponding in 5-year-capacity ponds
followed by removal of the ash to a landfill has a capital investment of
32 $/kW and annual revenue requirements of 1.91 mills/kWh. There is no
apparent economic advantage in using temporary ponds with new power plants.
The costs for disposal of a self-hardening (high-calcium) ash are
slightly higher in cost per ton of ash than disposal costs for nonhardening
ash. The main cost differences are slightly higher truck costs for covered
beds and moisturizers, addition of compaction water at the landfill, and
slightly higher bottom ash water treatment costs. In many practical
situations these would be more than offset by the lower ash content of many
high-calcium coals.
In all cases, disposal site costs are the largest cost element in both
capital investment and annual revenue requirements. In pond-disposal
processes pond cost constitutes two-thirds of the capital investment. In
comparison, landfill capital investment constitutes about one-third of the
total capital investment in landfill disposal processes. In both cases,
construction functions involving earthmoving are the major cost factors. The
capital investment contribution to annual revenue requirements as capital
charges is the largest factor in total annual revenue requirements.
Trucking distance has little effect on capital investment because trucks
are a minor element in capital investment. Distance increases annual revenue
requirements moderately because of increased operating costs and labor
requirements. Moisture content has an important effect on trucking costs.
160
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Ash utilization has a significant effect on costs, particularly for pond
disposal processes. Fifty percent utilization reduces capital investment and
annual revenue requirements about one-fourth for pond disposal and one-sixth
for landfill disposal. For these cost savings to be fully realized, however,
the disposal site size must be designed for the reduced quantity of ash.
Although the design is considerably different, the costs for ash
collection do not differ greatly whether the ash is sluiced directly to ponds
or the bottom ash is dewatered and the fly ash is collected dry for trucking
to landfills. The capital investment for truck transportation (including
storage silos) is, however, about one-third higher than the capital investment
for sluicing and the annual revenue requirements for trucking are about twice
as high as those for sluicing.
Hopper costs are a major element in overall ash disposal capital
investment. Changes in the size or design of the hoppers will significantly
affect disposal costs.
Capital investment and annual revenue requirements for bottom ash
disposal are about twice as high as those for fly ash disposal in terms of
cost per ton of ash, primarily because of the economy of scale in equipment
and disposal site costs for the higher volume of fly ash.
Base case 1 direct capital investment, excluding ponds, operating and
maintenance costs, and electricity, are in general agreement with selected
equivalent TVA costs when the TVA costs are adjusted for unit size and cost-
basis year.
161
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REFERENCES
1. Recent projections of coal use pertinent to U.S. utilities have been made
by numerous government and private organizations. Among these are the
recent reports of the World Coal Study Group. Coal-Bridge to the Future
and Future Coal Prospects (Ballinger Publishing Co.. Cambridge,
Massachusetts) and various other studies that have been discussed in
journals, such as the Coal Data Book, report of the President's
Commission on Coal, 1980, U.S. Government Printing Office, Washington,
D.C.; E. D. Griffith, 1979, Coal in Transition; 1985-2000, Mining
Congress Journal, Vol. 65, No. 2, pp.2 9-33; E. T. Hayes, 1979, Energy
Resources Available to the United States, 1985 to 2000, Science,
Vol. 203, No. 4377, pp. 233-239; F. C. Olds, 1979, Coal Resources and
Outlook, Power Engineering, Vol. 83, No. 10, pp. 71-78; D. Bodansky,
1980, Electrical Generation Choices for the New Term, Science, Vol. 207,
No. 4432, pp. 721-728; and E. Marshall, 1980, Energy Forecasts; Sinking
to New Lows, Science, Vol. 208, pp. 1353-1354, 1356, Trade journals such
as CoaJL Outlook (Pasha Publications) provide topical information.
2. Friedlander, G. D., 1978, Fifteenth Steam Station Design Survey,
Electrical World, Vol. 190, No. 10, November 15, pp. 73-87.
3. Berman, I. M., 1981, New Generating Capacity; When, Where, and By Whom,
Power Engineering, Vol. 85, No. 4, pp. 72-81.
4. Faber, J. H., 1976, U.S. Overview of Ash Production and Utilization,
In: Ref. 71, pp. 5-13.
5. Bureau of Mines, 1980, Mineral Commodity Summaries, U.S. Department of the
Interior, Washington, B.C.
6. Averitt, P., 1975, Coal Resources of the United States, January 1, 1974,
Bulletin 1412, U.S. Geological Survey, Washington, D.C.
7. Westerstrom, L. W., 1975, Bituminous Coal and Lignite, In: Mineral Facts
and Problems, U.S. Bureau of Mines Bulletin 667, pp. 157-172.
Keystone Coal Manual, 1979, Coal Seams and Fields, pp. 444-624, pocket
map. This section describes coal deposits, mining operations, coal
analyses, and other information by state.
8. Department of Energy, 1980, Electric Power Supply and Demand for the
Contiguous United States 1980-1989 (Preliminary), DOE/RG-0036, U.S.
Department of Energy, Washington, D.C.
162
-------
9. Department of Energy, 1978, Status of Coal Supply Contracts for New
Electric Generating Units, DOE/FERC-0004/1, U.S. Department of Energy,
Washington, D.C.
10. Engineering-Science, 1979, Evaluation of the Impacts of Proposed RCRA
Regulations and Other Related Federal/Environmental Regulations on Utility
and Industrial Sector Fossil Fuel-Fired Facilities, Interim Report,
Phase I-Utility Sector, Office of Coal Utilization, U.S. Department of
Energy, Washington, D.C.
11. Federal Register, 1979, New Stationary Sources Performance Standards;
Electric Utility Steam Generating Units, Vol. 44, No. 113, June 11,
pp. 33580-33624.
12. Coal Age, 1980, Western Coal; Tonnage Climbs as Markets Expand, Vol. 85,
No. 5, May 1980, pp. 67-87.
13. Radian Corporation, 1979, Chemical/Physical Stability of Flue Gas Cleaning
Wastes, EPRI FP-671, Electric Power Research Institute, Palo Alto,
California.
14. Gibbs & Hill, Inc., 1978, Coal Preparation for Combustion and Conversion,
EPRI AF-791, Electric Power Research Institute, Palo Alto, California.
15. Babcock & Wilcox, 1975, Steam/Its Generation and Use, Babcock & Wilcox
Company, New York.
16. Fryling, G. R., 1966, Combustion Engineering, Combustion Engineering,
Incorporated, New York.
17. Burbach, H. F., 1979, Modern Utility Coal-Fired Steam Generators, In:
1979 Keystone Coal Manual, McGraw-Hill, New York, pp. 308-319.
18. Buonicare, A. V., J. P. Reynolds, and L. Theodore, 1978, Control
Technology for Fine-Particulate Emissions, ANL/ECT-5, Argonne National
Laboratory, Argonne, Illinois, p. 29.
19. White, H. J., 1977, Electrostatic Precipitation of Fly Ash, Air Pollution
Control Association, Pittsburgh, Pennsylvania.
20. Noyes Data Corporation, 1978, Trace Contaminants from Coal, S. Torrey,
ed.» Noyes Data Corporation, Park Ridge, New Jersey.
21. Akers, D. J., B. G. McMillan, and J. W. Leonard, 1978, Coal Minerals
Bibliography, FE-2692-5, Department of Energy, Washington, D.C.
22. Fred C. Hart Associates, Inc., 1978, The Impact of RCRA (PL 94-580) on
Utility Solid Wastes, EPRI FP-878, Electric Power Research Institute, Palo
Alto, California.
163
-------
23. Radian Corporation, 1979» Review and Assessment of the Existing Data Base
Regarding Flue Gas Cleaning Wastes, EPRI FP-671, Electric Power Research
Institute, Palo Alto, California.
24. Southern Research Institute, 1977, Environmental Control Implications of
Generating Electric Power from Coal, ANL/ECT-3, Appendix E, Argonne
National Laboratory, Argonne, Illinois.
25. Fisher, G. L., D. P. Y. Chang, M. Brummer, 1976, Ash Collected from
Electrostatic Precipitators; Microcrystalline Structures and the Mystery
of the Spheres, Science, Vol. 192, No. 4239, pp. 553-555.
26. deZeeuw, H. J., and R. V. Abresch, 1976, Cenospheres from Dry Fly Ash, In:
Ref. 71. pp. 386-395.
27. Fisher, G. L., 1979, The Morphogenesis of Coal Fly Ash, In: Ref. 46,
Vol. 4, pp. 433-439.
28. Rose, J. G., J. A. Lowe, and R. K. Floyd, 1979, Composition and Properties
of Kentucky Power Plant Ash, In: Ref. 72, Vol. 1, pp. 220-244.
29. Ray, S. S., and F. G. Parker, 1977, Characterization of Ash from Coal-
Fired Power Plants, EPA-600/7-77-010, U.S. Environmental Protection
Agency, Washington, D.C.
30. McBride, J. P., R. E. Moore, J. P. Witherspoon, and R. E. Blanco, 1978,
Radiological Impact of Airborne Effluents of Coal and Nuclear Plants,
Science, Vol. 202, No. 4372, pp. 1045-1050.
31. Morris, J. S., and G. Bobrowski, 1979, The Determination of 226Ra,
214pb, and 214si in Fly Ash Samples from Eighteen (18) Coal-Fired Power
Plants in the United States, In: Ref. 72, Vol. 1, pp. 460-469.
32. Coles, D. G., R. C. Ragaini, J. M. Ondov, G. L. Fisher, D. Silberman, and
B. A. Prentice, 1979, Chemical Studies of Stack Fly Ash from a Coal-
Fired Power Plant, Environmental Science and Technology, Vol. 13, No. 4,
pp. 455-459.
33. Chae, Y. S., and J. L. Snyder, 1977, Vibratory Compaction of Fly Ash, In:
Geotechnical Practice for Disposal of Solid Waste Materials, American
Society of Civil Engineers, New York, pp. 41-62.
34. Srinivasan, V., G. H. Beckwith, and H. H. Burke, 1977, Geotechnical
Investigations of Power Plant Wastes, In: Geotechnical Practice for
Disposal of Solid Waste Materials, American Society of Civil Engineers,
New York, pp. 169-187.
35. Seals, R. K., L. K. Moulton, and D. L. Kinder, 1977, In Situ Testing of a
Compacted Fly Ash Fill, In: Geotechnical Practice for Disposal of Solid
Waste Materials, American Society of Civil Engineers, New York,
pp. 493-516.
36. GAI Consultants, Inc., 1979, Fly Ash Structural Fill Handbook, EPRI
EA-1281, Electric Power Research Institute, Palo Alto, California.
164
-------
37. Meikle, P. G., 1975, Fly Ash. In: Solid Wastes: Origin, Collection,
Processing, and Disposal, C. L. Mantell, ed.» John Wiley & Sons, New York.
38. A Primer on Ash Handling Systems, Trade Bulletin, 1976, Allen-Sherman-Hoff
Co., Malvern, Pennsylvania.
39. Cunningham, J. A., R. G. Lukas, and T. C. Anderson, 1977, Impoundment of
Fly Ash and Slag - A Case Study, In: Geotechnical Practice for Disposal
of Solid Waste Materials, American Society of Civil Engineers, New York,
pp. 227-245.
40. DiGioia, A. M., J. F. Meyers, and J. E. Niece, 1977, Design and Construc-
tion of Bituminous Fly Ash Disposal Sites, In: Geotechnical Practice for
Disposal of Solid Waste Materials, American Society of Civil Engineers,
New York, pp. 267-284.
41. Caplan, K. J., 1977, Source Control by Centrifugal Force and Gravity, In:
Air Pollution, Vol. IV, Engineering Control of Air Pollution, A. C. Stern,
ed., Academic Press, New York, pp. 190-256.
42. Smith, M., M. Melia, and N. Gregory, 1980, EPA Utility Survey; October-
December 1979, EPA-600/7-80-029a, U.S. Environmental Protection Agency,
Washington, D.C.
43. Harmon, D. L., and L. E. Sparks, 1979, Conclusions from EPA Scrubber R&D,
In: Ref. 46, Vol. 3, pp. 193-217.
44. Bechtel Corporation, 1976, Evaluation of Dry Alkalis for Removing Sulfur
Dioxide from Boiler Flue Gases, EPRI-FP-207, Electric Power Research
Institute, Palo Alto, California.
45. Reigel, S. A., and R. P. Bundy, 1977, Why the Swing to Baghouses?,
Environmental Management, Vol. 121, No. 1, pp. 68-73.
46. U.S. EPA, 1979, Symposium on the Transfer and Utilization of Particulate
Control Technology, in 4 volumes, F. P. Venditte, J. A. Armstrong, and
M. Durham, eds.; Volume 1, Electrostatic Precipitators, EPA-600/7-79-044a;
Volume 2, Fabric Filters and Current Trends in Control Equipment,
EPA-600/7-79-044b; Volume 3, Scrubbers, Advanced Technology, and HTP
Applications, EPA-600/7-79-044c; Volume 4, Fugitive Dusts and Sampling,
Analysis, and Characterization of Aerosols, EPA-600/7-79-044d.
47. Miller, F. J., D. E. Gardner, J. A. Graham, R. E. Lee, Jr., W. E. Wilson,
and J. D. Bachmann, 1979, Size Considerations for Establishing a Standard
for Inhalable Particles, Journal APCA, Vol. 29, No. 6, pp. 610-615.
48. Oglesby, S., Jr., and G. B. Nichols, 1977, Electrostatic Precipitation,
In: Air Pollution, Vol. IV, Engineering Control of Air Pollution, A. C.
Stern, ed., Academic Press, New York, pp. 190-256.
49. Reference 46, Vol. 1. This volume contains several articles on flue gas
conditioning.
165
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50. Moulton, L. K., 1973, Bottom Ash and Boiler Slag, In: Ref. 70,
pp. 148-168.
51. Majidzadeh, K., G. Bokowski, R. El-Mitiny, 1979, Material Characteristics
of Power Plant Bottom Ashes and Their Performance in Bituminous Mixtures;
A Laboratory Investigation, In: Ref. 72, Vol. 2, pp. 787-804.
52. Ash Handling Design Information Manual, 1979, trade bulletin, United
Conveyor Corp., Deerfield, Illinois. See also Ref. 38.
53. Cochran, R. A., 1980, Ash Handling, American Vs. European Design, preprint
(Chas. T. Main, Inc., Boston), paper presented at the American Power
Conference, April 1980, Chicago.
54. Singer, J. G., G. A. Mellinger, and A. J. Cozza, 1979, Design for
Continuous Ash Removal, preprint (Combustion Engineering, Inc., Windsor,
Conn.), paper presented at the American Power Conference, April 1979,
Chicago.
55. Mitchell, F. L.» 1980, Bottom Ash Handling System, preprint (Associated
Electric Cooperative, Inc.), paper presented at the 31st Annual Conference
of the Association of Rural Electric Generating Cooperatives, June 1980.
56. Arnold, B., and M. Saleh, 1980, Dense-Phase Fly Ash Conveying System,
Combustion, Vol. 51, No. 10, pp. 38-40.
57. Versar, Inc., 1979, Selection of Representative Coal Ash and Coal Ash/FGD
Waste Disposal Sites for Future Testing, draft report, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
58. Jones, B. F., J. S. Sherman, D. L. Jernigan, E. P. Hamilton III, and
D. M. Otlmers, 1978, Study of Non-hazardous Wastes from Coal-Fired
Electric Utilities, draft report, Radian Corp., to EPA. Cited in Ref. 60.
59. American Society of Civil Engineers, 1977, Geochemical Practice for
Disposal of Solid Waste Materials, American Society of Civil Engineers,
New York. Several specific ash disposal sites and practices are
discussed. Selected ash disposal practices are also discussed in Ref. 10.
60. References 82, 83, and 84 contain numerous examples of intermittent
high-volume ash utilization projects.
61. Santhanam, C. J., R. R. Lunt, C. B. Cooper, D. E. Klimschmidt, I. Bodek,
W. A. Tucker, and C. R. Ullrich, 1980, Waste and Water Management for
Conventional Coal Combustion Assessment Report - 1979, Vol. V. Disposal
of FGC Wastes, EPA-600/7-80-012e, U.S. Environmental Protection Agency,
Washington, D.C.
62. Rice, J. K., and S. D. Strauss, 1977, Water Pollution Control in Steam
Plants, Power, Vol. 120, No. 4, pp. S-l - S-20.
63. Reference 10 contains comparisons of RCRA and State regulations.
166
-------
64. Burns & Roe, Inc., 1974, Development Document for Effluent Limitations
Guidelines and New Source Performance Standards for the Steam Electric
Power Generating Point Source Category, EPA-4401/l-74/029a. U.S. Environ-
mental Protection Agency, Washington, D.C.
65. Hittman Associates, Inc., 1978, Technical Report for Revision of Steam
Electric Effluent Limitations Guidelines, draft, U.S. Environmental
Protection Agency, Washington, D.C.
66. Federal Register, 1980, Effluent Limitations Guidelines, Pretreatment
Standards and New Source Performance Standards Under Clean Water Act;
Steam Electric Power Generating Point Source Category, proposed
regulation, Vol. 45, No. 200, October 14, pp. 68328-68356.
67. Duvel, W. A., and S. E. Gaines, 1979, RCRA and Hazardous Waste Management
Regulations, Pollution Engineering, Vol. 11, No. 12, pp. 66-73.
68. Federal Register, 1978, Identification and Listing of Hazardous Wastes,
Vol. 43, December 18, pp. 59054-59268.
69. Federal Register, 1979, Identification and Listing of Hazardous Wastes,
Vol. 44, No. 164, August 22, pp. 49402-49404.
70. Engineering News Record, 1980, Billions at Stake in Coal Waste Fight,
January 10, is typical of numerous journal comments.
71. Faber, J. H.» A U.S. Overview of Ash Production and Utilization, In:
Ref. 84, Pt. 1, pp. 24-28.
72. Radian Corporation, 1975, Environment Effects of Trace Elements from
Ponded Ash and Scrubber Sludge, EPRI 202, Electric Power Research
Institute, Palo Alto, California.
73. Theis, T. L., 1978, Field Investigation of Trace Metals in Groundwater
from Fly Ash Disposal, Journal WPCF, Vol. 50, No. 11, pp. 2457-2469.
74. Miller, F. A., Ill, T.-Y. J. Chu, and R. J. Ruane, 1979, Design of a
Monitoring Program for Ash Pond Effluents, EPA-600/7-79-236, U.S.
Environmental Protection Agency, Washington, D.C.
75. GAI Consultants, Inc., 1979, Coal Ash Disposal Manual. EPRI FP-1257,
Electric Power Research Institute, Palo Alto, California.
76. Federal Register, 1980, Hazardous Waste Management; Overview and
Definitions, Generator Regulations, Transporter Regulations, Vol. 45,
No. 39, February 26, pp. 12722-12744.
77. Federal Register, 1980, Vol. 45, No. 98, May 19, Final rules and interim
rules effective November 19, 1980, and requests for comment were published
under eight titles: Hazardous Waste Management System; General,
pp. 33066-33082; Hazardous Waste Management System; Identification and
Listing of Hazardous Wastes, pp. 33084-33133; Identification and Listing
167
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of Hazardous Wastes; Proposed Additions, pp. 33136-33137. Standards for
Generators of Hazardous Wastes, pp. 33140-33148; Standards for
Transporters of Hazardous Wastes, pp. 33150-33152; Standards for Owners
and Operators of Hazardous Waste Treatment, Storage, and Disposal
Facilities, pp. 33154-33258; Financial Requirements for Owners and
Operators of Hazardous Waste Management Facilities, pp. 33260-33276;
Hazardous Waste Management; Interim Status, Requirements for Underground
Iniection. pp. 33278-33285.
78. Federal Register, 1979, Criteria for Classification of Solid Waste
Disposal Facilities and Practices, Vol. 44, No. 179, September 13,
pp. 53438-53464. See also Vol. 44, No. 185, September 21, p. 54708 for
corrections.
79. American Water Works Association, 1979, Proceedings of the Water Reuse
Symposium, March 25-30, 1979, 3 volumes, AWWA Research Foundation, Denver,
Colorado. These volumes illustrate the scope and technology of such
efforts although there is little direct treatment of utility practices.
80. Chu, T.-Y. J., P. A. Krenkel, and R. J. Ruane, 1979, Reuse of Ash Sluicing
Water in Coal-Fired Power Plants, Proceedings of the Third National
Conference on Complete Water Reuse, Am. Inst. of Chem. Engrs./U.S.
Environmental Protection Agency, pp. 326-336.
81. Noblett, J. G., and P. G. Christman, 1978, Water Recycle/Reuse
Alternatives in Coal-Fired Steam-Electric Power Plants; Volume I,
EPA-600/7-78-055a, Plant Studies and General Implementation Plans;
Volume II, Appendixes, EPA-600/7-78-055b, U.S. Environmental Protection
Agency, Washington, D.C.
82. Proceedings; Third International Ash Utilization Symposium, J. H. Faber,
W. E. Eckard, and J. D. Spencer, eds., Information Circular 8640, U.S.
Bureau of Mines, Washington, D.C.
83. Proceedings; Fourth International Ash Utilization Symposium, J. H. Faber,
A. W. Babcock, and J. D. Spencer, eds., MERC/SP-76-4, (CONF-760322) Energy
Research & Development Administration, Morgantown, West Virginia.
84. Proceedings; Fifth International Ash Utilization Symposium, J. H. Faber,
A. W. Babcock, J. D. Spencer, and C. E. Whieldon, Jr., compilers and eds.,
METC/SP-79/10 (Pt. 1 and Pt. 2) U.S. Department of Energy, Morgantown,
West Virginia.
85. Ness, H. M., P. Richmond, G. Eurick, and R. Kruger, 1979, Power Plant Flue
Gas Desulfurization Using Alkaline Fly Ash from Western Coals, In:
Proceedings: Symposium on Flue Gas Desulfurization, Las Vegas, Nevada,
March 1979, Volume II, EPA-600/7-79-167b, U.S. Environmental Protection
Agency, Washington, D.C., pp. 809-834.
86. Michael Baker, Jr., Inc., 1978, State-of-the-Art of FGD Sludge Fixation,
EPRI FP-671, Volume 3, Electric Power Research Institute, Palo Alto,
California.
168
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87. Department of Energy, 1978, Steam-Electric Plant Construction Cost and
Annual Production Expenses 1977, DOE/EIA-0033/3 (77), U.S. Department of
Energy, Washington, D.C. DOE, 1979, Steam-Electric Plant Air and Water
Quality Control Data, For the Year Ended December 31. 1976, DOE/FERC 0036,
U.S. Department of Energy, Washington, D.C. These are issued annually.
88. Cavallaro, J. A., M. T. Johnston, A. W. Deurbrouck, 1976, Sulfur Reduction
Potential of U.S. Coals; A Revised Report of Investigations, EPA-
600/2-76-091, U.S. Environmental Protection Agency, Washington, D.C., and
RI 81189 Bureau of Mines, U.S. Department of the Interior, Washington,
D.C.
89. National Coal Association, 1979, Steam-Electric Plant Factors, 1979,
National Coal Association, Washington, D.C.
90. Electric Power Research Institute, 1978, Technical Assessment Guide, EPRI
PS-866-SR, Electric Power Research Institute, Palo Alto, California.
91. Jeynes, P. H., 1968, Profitability and Economic Choice, 1st Ed, The Iowa
State University Press, Ames, Iowa.
92. Economic Indicators, 1976-1979, Chemical Engineering, Vols. 83 to 86.
93. Battelle, Columbus Laboratories, 1978, Analysis of Variance in Costs of
FGD Systems. EPRI FP-909, Electric Power Research Institute, Palo Alto,
California.
94. Smith, M., M. Melia, and N. Gregory, 1980, EPA Utility FGD Survey,
EPA-600/7-80-029a, U.S. Environmental Protection Agency, Washington, D.C.
95. Bahor, M. P. (GAI Consultants, Inc.) and K. L. Ogle (Tennessee Valley
Authority), 1981, Economic Analysis of Wet Versus Dry Ash Disposal
Systems, EPA-600/7-81-013, U.S. Environmental Protection Agency,
Washington, D.C.
169
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APPENDIX A
BASE CASE CAPITAL INVESTMENT AND ANNUAL REVENUE REQUIREMENTS
171
-------
TABLE A-l, CAPITAL INVESTMENT - BASE CASE 1,
DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Direct Investment
Ash collection
Ash transportation to disposal site
Ash disposal site
Water treatment and i~ecycle
Total process areas
Services, utilities, and miscellaneous
Total direct investment
Investment, 1982 k$
Fly ash Bottom ash
1,193
915
8,509
5_4
10,671
427
11,098
821
951
2,127
14
3,913
157
4,070
Total
2,014
1,866
10,636
14,584
584
15,168
Indirect Investment
Engineering design and supervision
Architect and engineering contractor
Construction expense
Contractor fees
Total indirect investment
312
158
933
577
1,979
155 467
77 234
363 1,296
222 799
817
2,796
Contingency
Total fixed investment
489
5,376
1,796
19,760
Other Capital Investment
Allowance for startup and modifications 248 204
Interest during construction 2,245 838
Total depreciable investment 16,877 6,418 23,295
Land 1,560 390 1,950
Working capital 444 171 615
Total capital investment 18,881 6,979 25,860
$/kW
37.76
13.96
51.72
Basis: New, 500-MW, midwestern, dry-bottom, pulverized-coal-fired
boiler with a 30-year, 165,000-hour life and a 9,500 Btu/kWh heat rate.
Eastern low-calcium coal with a 11,700 Btu/lb heating value, 3.36%
sulfur, 15.1% ash, as fired, producing 62,400 Ib/hr of ash as 80% fly
ash and 20% bottom ash. Fly ash removal to meet 0.03 Ib/MBtu NSPS.
Separate 30-year fly ash and bottom ash ponds one mile from the power
plant based on 55 Ib/ft dry bulk density of settled ash, 165,000 hours
of operation, and no ash utilization. Costs are projected to mid-1982
and include bottom, economizer, air heater, and ESP ash hoppers and
all subsequent equipment and facilities.
172
^^^KiJKr^lS^^^^i^^BSJfe
-------
TABLE A-2. ANNUAL REVENUE REQUIREMENTS
BASE CASE 1, DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Fly ash,
Annual
Annual revenue category Cost, $/unit quantity
Direct Costs
Conversion costs
Operating labor 15.00/man-hr 7,040 man-hr
Process reagents
H2S04 (100% equivalent) 65.00/ton 44 tons
Utilities
Water 0.014/kgal 393,200 kgal
Electricity 0.037/kWh 1,135,100 kWh
Maintenance
Process
Pond
Sampling and analysis 21.00/man-hr 1,000 man-hr
Total direct costs
Indirect Costs
Plant and administrative overheads
(60% of conversion costs less utilities)
Total first-year operating and maintenance costs
Levelized capital charges
(14.7% of total capital investment)
Total first-year annual revenue requirements
Levelized first-year operating and maintenance costs
(1.886 x first-year operating and maintenance costs)
Levelized capital charges (14.7% of total capital
investment)
Total levelized annual revenue requirements
Equivalent unit revenue requirements
Unit first-year revenue requirements
k$
Mills/kWh
$/ton dry ash
Unit levelized revenue requirements
k$
Mills/kWh
$/ton dry ash
1984 k$
Annual
revenue
requirements
105.6
2.9
5.5
42.0
161.2
176.8
21.0
515.0
280.5
795.5
2.775.5
3,571.0
1,500.3
2,775.5
4,275.8
3,571
1.30
26.01
4,276
1.55
31.15
Bottom ash, 1984 k$
Annual
Annual revenue
quantity requirements
6,710 man-hr 100.7
11 tons 0.7
98,310 kgal 1.4
517,300 kWh 19.1
125.8
44.2
1,000 man-hr 21.0
312.9
175.5
488.4
1,025.9
1,514.3
921.1
1,025.9
1,947.0
1,514
0.55
44.12
1,947
0.71
56.73
Total,
1984 k$
Annual
revenue
requirements
206.3
3.6
6.9
61.1
287.0
221.0
42.0
827.9
456.0
1,283.9
3,801.4
5,085.3
2,421.4
3,801.4
6,222.8
5,085
1.85
29.63
6,223
2.26
36.26
Basis: One-year, 5,500-hour full-load operation of the system described in the capital investment summary; costs
projected to mid-1984.
173
-------
TABLE A-3. CAPITAL INVESTMENT - BASE CASE 2,
DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Investment, 1982 k$
Direct Investment
Ash collection
Ash transportation to disposal site
Ash disposal site
Water treatment and recycle
Total process areas
Services, utilities, and miscellaneous
Total direct investment
Fly ash Bottom ash
1,193
915
8,509
560
11,177
447
11,624
821
951
2,127
141
4,040
162
4,202
Total
2,014
1,863
10,636
701
15,217
609
15,826
Indirect Investment
Engineering design and supervision
Architect and engineering contractor
Construction expense
Contractor fees
Total indirect investment
343
173
985
608
2,109
164
81
376
231
852
507
254
1,361
839
2,961
Contingency
Total fixed investment
506
5,560
1,879
20,666
Other Capital Investment
Allowance for startup and modifications 305 219 524
Interest during construction 2,357 867 3,224
Total depreciable investment 17,768 6,646 24,414
Land 1,560 390 1,950
Working capital 473 185 658
Total capital investment 19,801 7,221 27,022
$/kW
39.60
14.44
54.04
Basis: New, 500-MW, midwestern, dry-bottom, pulverized-coal-fired
boiler with a 30-year, 165,000-hour life and a 9,500 Btu/kWh heat rate.
Eastern low-calcium coal with a 11,700 Btu/lb heating value, 3.36%
sulfur, 15.1% ash, as fired, producing 62,400 Ib/hr of ash as 80% fly
ash and 20% bottom ash. Fly ash removal to meet 0.03 Ib/MBtu NSPS.
Separate 30-year fly ash and bottom ash ponds one mile from the power
plant based on 55 lb/ft^ dry bulk density of settled ash, 165,000 hours
of operation, and no ash utilization. Costs are projected to mid-1982
and include bottom, economizer, air heater, and ESP ash hoppers and
all subsequent equipment and facilities.
174
-------
TABLE A-4. ANNUAL REVENUE REQUIREMENTS
BASE CASE 2, DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Annual revenue category Cost, $/unit
Fly ash, 1984 k$
Annual
quantity
Annual
revenue
requirements
Bottom ash, 1984 k$
Annual
quantity
Total,
1984 k$
Annual Annual
revenue revenue
requirements requirements
Direct Costs
Conversion costs
Operating labor
Process reagents
15.00/man-hr
7,920 man-hr
H2S04 (100X equivalent) 65.00/ton
93% limestone 8.50/ton
Commercial lime 75.00/ton
Sodium carbonate 160.00/ton
Utilities
Water 0.014/kgal
Electricity 0.037/kWh
Maintenance
Process
Pond
44 tons
46 tons
36 tons
95 tons
30,100 kgal
1,684,200 kWh
Sampling and analysis
Total direct costs
21.00/man-hr
1,400 man-hr
2.9
0.4
2.7
15.1
0.4
62.3
196.7
176.8
29.4
605.5
6,930 man-hr
11 tons
11 tons
9 tons
24 tons
7,500 kgal
654,600 kWh
1,400 man-hr
104.0
0.7
0.1
0.7
3.8
0.1
24.2
135.3
44.2
29.4
342.5
3.6
0.5
3.4
18.9
0.5
86.5
332.0
221.0
58.8
948.0
Indirect Costs
Plant and administrative overheads
(60% of conversion costs less utilities)
325.7
190.9
Total first-year operating and maintenance costs
931.2
533.4
1,464.6
Levelized capital charges
(14.7% of total capital investment)
Total first-year annual revenue requirements
2,910.7
3,841.9
1,061.5
1,594.9
3,972.2
5,436.8
Levelized first-year operating and maintenance costs
(1.886 x first-year operating and maintenance costs)
Levelized capital charges (14.7% of total capital
investment)
Total levelized annual revenue requirements
Equivalent unit revenue requirements
4,666.9
2,067.5
6,734.4
Unit first-year revenue requirements
k$
Mills/kWh
$/ton dry ash
Unit levelized revenue requirements
k$
MLlls/kWh
$/ton dry ash
3,842
1.40
27.99
4,667
1.70
34.00
1,595 5,437
0.58 1.98
46.47 31.68
2,067 6,734
0.75 2.45
60.24 39.24
Basis: One-year, 5,500-hour full-load operation of the system described in the capital investment summary; costs
projected to mid-1984.
175
-------
TABLE A-5. CAPITAL INVESTMENT
BASE CASE 3, HOLDING PONDS AND LANDFILL OF NONHARDENING ASH
Investment, 1982 k$
Direct Investment
Ash collection
Ash transportation to disposal site
Ash disposal site
Water treatment and recycle
Total process areas
Services, utilities, and miscellaneous
Total direct investment
Fly ash Bottom ash
1,195
960
4,359
108
6,622
265
6,887
796
680
1,064
31
2,571
103
2,674
Total
1,991
1,640
5,423
139
9,193
368
9,561
Indirect Investment
Engineering design and supervision
Architect and engineering contractor
Construction expense
Contractor fees
Total indirect investment
251
126
543
330
1,250
116
58
222
135
531
367
184
765
465
1,781
Contingency
Total fixed investment
720
8,857
288
3,493
Other Capital Investment
Allowance for startup and modifications 194 147 341
Interest during construction 1,235 496 1,731
Total depreciable investment 10,286 4,136 14,422
Land 848 212 1,060
Working capital 494 153 647
Total capital investment 11,628 4,501 16,129
$/kW
23.26
9.00
32.26
Basis: New, 500-MW, midwestern, dry-bottom, pulverized-coal-fired
boiler with a 30-year, 165,000-hour life and a 9,500 Btu/kWh heat rate.
Eastern low-calcium coal with a 11,700 Btu/lb heating value, 3.36%
sulfur, 15.1% ash, as fired, producing 62,400 Ib/hr of ash as 80% fly
ash and 20% bottom ash. Fly ash removal to meet 0.03 Ib/MBtu NSPS.
Separate 5-year ponds for fly ash and bottom ash and combined 25-year
landfill 1,600 feet and 1 mile from power plant, respectively, based
on 55 lb/ft3 pond and 90 lb/ft3 landfill dry bulk density and 165,000
hours of operation and no ash utilization. Costs are projected to
mid-1982 and include bottom, economizer, air heater, and ESP ash
hoppers and all subsequent equipment and facilities.
176
-------
TABLE A-6. ANNUAL REVENUE REQUIREMENTS
BASE CASE 3, HOLDING PONDS AND LANDFILL FOR NONHARDENING ASH
Fly ash,
Annual
Annual revenue category Cost, $/unit quantity
Direct Costs
Conversion costs
, Operating labor 15.00/man-hr 43,560 man-hr
Process reagents
H2S04 (100% equivalent) 65.00/ton 176 tons
Utilities
Water 0. 014/kgal 394,200 kgal
Electricity 0.037/kWh 1,020,400 kWh
Diesel fuel 1.20/gal 130,000 gal
Maintenance
Process
Pond landfill
Sampling and analysis 21. 00/man-hr 1,720 man-hr
Contracted ash pumping 1.35/yd3 135,300 yd3
Total direct costs
Indirect Costs
Plant and administrative overheads
(60% of conversion costs less utilities)
Total first-year operating and maintenance costs
Levelized capital charges
(14.7% of total capital investment)
Total first-year annual revenue requirements
Levelized first-year operating and maintenance costs
(1.886 x first-year operating and maintenance costs)
Levelized capital charges (14.7% of total capital
investment)
Total levelized annual revenue requirements
Equivalent unit revenue requirements
Unit first-year revenue requirements
k$
Mills/kWh
$/ton dry ash
Unit levelized revenue requirements
k$
Mills/kWh
$/ton dry ash
1984 k$
Annual
revenue
requirements
653.4
11.4
5.5
37.8
156.0
229.9
98.8
36.0
182.7
1,411.5
727.3
2,138.8
1,709.3
3,848.1
1
4,033.8
1,709.3
5,743.1
3,848
1.40
28.03
5,743
2.09
41.83
Bottom ash, 1984 k$
Annual
Annual revenue
quantity requirements
15,840 man-hr 237.6
44 tons 2.9
98,600 kgal 1.4
237,500 kWh 8.8
32,500 gal 39.0
132.6
24.7
1,610 man-hr 33.8
480.8
259.0
739.8
661.7
1,401.5
1,395.2
661.7
2,056.9
1,402
0.51
40.84
2,057
0.75
59.93
Total,
1984 k$
Annual
revenue
requirements
891.0
14.3
6.9
46.5
195.0
362.5
123.5
69.9
182.7
1,892.3
986.3
2,878.6
2,371.0
5,249.6
5,429.0
2,371.0
7,800.0
5,250
1.91
30.59
7,800
2.84
45.45
Basis: One-year, 5,500-hour full-load operation of the system described in the capital investment summary; costs
projected to mid-1984.
177
-------
TABLE A-7. CAPITAL INVESTMENT
BASE CASE 4, DIRECT LANDFILL OF NONHARDENING ASH
Direct Investment
Ash collection
Ash transportation to disposal site
Ash disposal site
Water treatment and recycle
Total process areas
Services, utilities, and miscellaneous
Total direct investment
Investment, 1982 k$
Fly ash Bottom ash Total
1,400
1,516
2,280
54
5,250
210
5,460
821
1,048
571
387
2,827
113
2,940
2,221
2,564
2,851
441
8,077
323
8,400
Indirect Investment
Engineering design and supervision
Architect and engineering contractor
Construction expense
Contractor fees
Total indirect investment
295 167 462
147 84 231
485 282 767
295 167 462
1,222
700
1,922
Contingency
Total fixed investment
611
7,293
350
3,990
961
11,283
Other Capital Investment
Allowance for startup and modifications
Interest during construction
Total depreciable investment
Land
Working capital
Total capital investment
315
1,049
8,657
568
427
9,652
252
601
4,843
142
116
5,101
13,500
710
543
14,753
$/kW
19.32
10.19
29.51
Basis: New, 500-MW, midwestern, dry-bottom, pulverized-coal-fired
boiler with a 30-year, 165,000-hour life and a 9,500 Btu/kWh heat rate.
Eastern low-calcium coal with a 11,700 Btu/lb heating value, 3.36%
sulfur, 15.1% ash, as fired, producing 62,400 Ib/hr of ash as 80% fly
ash and 20% bottom ash. Fly ash removal to meet 0.03 Ib/MBtu NSPS.
Separate fly ash and bottom ash landfills 1 mile from the power plant
based on 90 Ib/ft^ dry bulk density of ash, 165,000 hours of operation,
and no ash utilization. Costs are projected to mid-1982 and include
bottom, economizer, air heater, and ESP ash hoppers and all subsequent
equipment and facilities.
178
-------
TABLE A-8. ANNUAL REVENUE REQUIREMENTS
BASE CASE 4, DIRECT LANDFILL OF NONHARDENING ASH
Fly ash,
Annual
Annual revenue category Cost, $/unlt quantity
Direct Costs
Conversion costs
Operating labor 15.00/man-hr 34,760 man-hr
Process reagents
H2SC>4 (100% equivalent) 65.00/ton 132 tons
Utilities
Water 0.014/kgal 3,700 kgal
Electricity 0.037/kWh 543,000 kWh
Diesel fuel 1.20/gal 81,600 gal
Maintenance
Process
Landfill
Sampling and analysis 21.00/man-hr 820 man-hr
Total direct costs
Indirect Costs
Plant and administrative overheads
(60% of conversion costs less utilities)
Total first-year operating and maintenance costs
Levelized capital charges
(14.7% of total capital investment)
Total first-year annual revenue requirements
Levelized first-year operating and maintenance costs
(1.886 x first-year operating and maintenance costs)
Levelized capital charges (14.7% of total capital
investment)
Total levelized annual revenue requirements
Equivalent unit revenue requirements
Unit first-year revenue requirements
k$
Mills/kWh
$/ton dry ash
Unit levelized revenue requirements
k$
Mills/kWh
$/ton dry ash
1984 k$
Annual
revenue
requirements
521.4
8.6
0.1
20.1
97.8
277.9
60.7
17.2
1,003.8
531.5
1,535.3
1,418.8
2,954.1
2,895.6
1,418.8
4,314.4
2,954
1.08
21.52
4,314
1.57
31.43
Bottom ash, 1984 k$
Annual
Annual revenue
quantity requirements
18,040 man-hr 270.6
198 tons 12.9
900 kgal 0.0
199,700 kWh 7.4
20,400 gal 24.5
198.2
15.2
710 man-hr 14.9
543.7
307.0
850.7
749.7
1,600.4
1,604.4
749.7
2,354.1
1,600
0.58
46.63
2,354
0.86
68.59
Total,
1984 k$
Annual
revenue
requirements
792.0
21.5
0.1
27.5
122.4
476.1
75.9
32.0
1,547.5
838.5
2,386.0
2,168.5
4,554.5
4,500.0
2,168.5
6,668.5
4,554
1.66
26.54
6,668
2.42
38.86
Basis: One-year, 5,500-hour full-load operation of the system described in the capital investment summary; costs
projected to mid-1984.
179
-------
TABLE A-9. CAPITAL INVESTMENT
BASE CASE 5, DIRECT LANDFILL OF SELF-HARDENING ASH
Direct Investment
Ash collection
Ash transportation to disposal site
Ash disposal site
Water treatment and recycle
Total process areas
Services, utilities, and miscellaneous
Total direct investment
Investment, 1982 k$
Fly ash Bottom ash
1,163
1,295
1,980
5J3
4,491
180
4,671
702
921
495
356
2,474
99
2,573
Total
1,865
2,216
2,475
409
6,965
279
7,244
Indirect Investment
Engineering design and supervision
Architect and engineering contractor
Construction expense
Contractor fees
Total indirect investment
243
122
408
243
1,016
146
73
241
146
606
389
195
649
389
1,622
Contingency
Total fixed investment
506
6,193
305
3,484
811
9,677
Other Capital Investment
Allowance for startup and modifications
Interest during construction
Total depreciable investment
Land
Working capital
Total capital investment
261
869
7,323
464
403
8,190
221
522
4,227
116
112
4,455
11,550
580
515
12,645
$/kW
16.38
8.91
25.29
Basis: New, 500-MW, inidwestern, dry-bottom, pulverized-coal-fired
boiler with a 30-year, 165,000-hour life and a 9,500 Btu/kWh heat rate.
Western high-calcium coal with a 9,700 Btu/lb heating value, 0.59%
sulfur, 9.7% ash, as fired, producing 47,730 Ib/hr of ash as 80% fly
ash and 20% bottom ash. Fly ash removal to meet 0.03 Ib/MBtu NSPS.
Separate fly ash and bottom ash landfills 1 mile from the power plant
based on 90 Ib/ft^ dry bulk density of settled ash, 165,000 hours of
operation, and no ash utilization. Costs are projected to mid-1982
and include bottom, economizer, air heater, and ESP ash hoppers and
all subsequent equipment and facilities.
180
-------
TABLE A-10. ANNUAL REVENUE REQUIREMENTS
BASE CASE 5, DIRECT LANDFILL OF SELF-HARDENING ASH
Fly ash,
Annual
Annual revenue category Cost, $/unit quantity
Direct Costs
Conversion costs
Operating labor 15.00/man-hr 38,280 man-hr
Process reagents
H2S04 (100% equivalent) 65.00/ton 132 tons
Utilities
Water 0.014/kgal 300 kgal
Electricity 0.037/kWh 398,600 kWh
Diesel fuel 1.20/gal 73,760 gal
Maintenance
Process
Landfill
Sampling and analysis 21.00/man-hr 820 man-hr
Total direct costs
Indirect Costs
Plant and administrative overheads
(60% of conversion costs less utilities)
Total first-year operating and maintenance costs
Levelized capital charges
(14.7% of total capital investment)
Total first-year annual revenue requirements
Levelized first-year operating and maintenance costs
(1.886 x first-year operating and maintenance costs)
Levelized capital charges (14.7% of total capital
investment)
Total levelized annual revenue requirements
Equivalent unit revenue requirements
Unit first-year revenue requirements
k$
Mills /kWh
$/ton dry ash
Unit levelized revenue requirements
k$
Mills/kWh
$/ton dry ash
1984 k$
Annual
revenue
requirements
574.2
8.6
0.1
14.7
88.5
242.4
50.8
17.1
996.4
535.9
1,532.3
1.203.9
2,736.2
2,889.9
1,203.9
4,093.8
2,736
1.00
26.06
4,094
1.49
38.99
Bottom ash, 1984 k$
Annual
Annual revenue
quantity requirements
18,920 man-hr 283.8
1,188 tons 77.2
100 kgal 0.0
109,900 kWh 4.1
18,440 gal 22.1
170.1
12.7
710 man-hr 14.9
584.9
335.2
920.1
654.8
1,574.9
1,735.3
654.8
2,390.1
1,575
0.57
59.99
2,390
0.87
91.01
Total,
1984 k$
Annual
revenue
requirements
858.0
85.8
0.1
18.8
110.6
412.5
63.5
32.0
1,581.3
871.1
2,452.4
1.858.7
4,311.1
4,625.2
1,858.7
6,483.9
4,311
1.57
32.84
6,484
2.36
49.40
Basis: One-year, 5,500-hour full-load operation of the system described in the capital investment summary;
projected to mid-1984.
181
-------
APPENDIX B
BASE CASE MODULAR CAPITAL INVESTMENT AND ANNUAL REVENUE REQUIREMENTS
183
-------
oo
TABLE B-l. MODULAR CAPITAL INVESTMENT BY TYPE OF EQUIPMENT
BASE CASE 1, DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Equipment, 1982 k$
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities,
and miscellaneous
Total direct investment
Total indirect investment
Contingency
Total fixed investment
Other capital charges
Total depreciable
investment
Land
Working capital
Total capital investment
$/kW
Hoppers
773
647
1,420
57
1,477
369
185
2,031
480
2,511
0
80
2,591
5.18
Process
488
717
1,205
48
1,253
314
156
1,723
405
2,128
0
329
2,457
4.92
Pipelines
0
1,323
1,323
54
1,377
343
172
1,892
447
2,339
0
161
2,500
5.00
Mobile
equipment
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Disposal site,
1982 k$
Pond Landfill
0
10,636
10,636
425
11,061
1,770
1,283
14,114
2,203
16,317
1,950
45
18,312
36.62
Total
1,261
13,323
14,584
584
15,163
2,796
1,796
19,760
3,535
23,295
1,950
615
25,860
51.72
-------
TABLE B-2. MODULAR ANNUAL REVENUE REQUIREMENTS BY TYPE OF EQUIPMENT
BASE CASE 1, DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
00
t_n
Annual revenue category Hoppers
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
Utilities
Water
Electricity
Maintenance
Sampling and analysis
i
Total direct costs
Indirect Costs
Capital charges
Levelized annual capital charges
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
84.2
0
0
0
118.0
0
202.2
380.9
121.3
502.2
704.4
0.25
4.10
Equipment
Process
110.8
0
6.9
61.1
100.0
37.8
316.6
361.2
149.2
510.4
827.0
0.30
4.82
, 1984 k$
Pipelines
3.0
0
0
0
69.0
0
72.0
367.5
43.2
410.7
482.7
0.18
2.81
Mobile
Disposal site,
1984 k$
equipment Pond Landfill
0
0
0
0
0
0
0
0
0
0
0
0
0
8.3
3.6
0
0
221.0
4.2
237.1
2,691.8
142.3
2,834.1
3,071.2
1.12
17.90
Total
206.3
3.6
6.9
61.1
508.0
42.0
827.9
3,801.4
456.0
4,257.4
5,085.3
1.85
29.63
-------
co
TABLE B-3. MODULAR CAPITAL INVESTMENT BY TYPE OF EQUIPMENT
BASE CASE 2, DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Equipment, 1982 k$
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities,
and miscellaneous
Total direct investment
Total indirect investment
Contingency
Total fixed investment
Other capital charges
Total depreciable
inves tment
Land
Working capital
Total capital investment
$/kW
Hoppers
773
647
1,420
57
1,477
369
185
2,031
480
2,511
0
80
2,591
5.18
Process
667
1,171
1,838
73
1,911
479
239
2,629
618
3,247
0
372
3,619
7.24
Pipelines
0
1,323
1,323
54
1,377
343
172
1,892
447
2,339
0
161
2,500
5.00
Mobile
equipment
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Disposal site,
1982 k$
Pond Landfill
0
10,636
10,636
425
11,061
1,770
1,283
14,114
2,203
16,317
1,950
45
18,312
36.62
Total
1,440
13,777
15,217
609
15,826
2,961
1,879
20,666
3,748
24,414
1,950
658
27,022
54.04
-------
TABLE B-4. MODULAR ANNUAL REVENUE REQUIREMENTS BY TYPE OF EQUIPMENT
BASE CASE 2, DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
00
Annual revenue category Hoppers
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
93% limestone
Commercial lime
Sodium carbonate
Utilities
Water
Electricity
Maintenance
Sampling and analysis
Total direct costs
Indirect Costs
Capital charges
Levelized annual capital charges
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
84.2
0
0
0
0
0
0
118.0
0
202.2
380.9
121.3
502.2
704.4
0.25
4.10
Equipment
, 1984 k$
Process Pipelines
127.3
0
0
0
0
86 5
145.0
54.6
413.9
532.0
196. 1
728.1
1,142.0
0.42
6.66
3.0
0
0
0
0
0
0
69.0
0
72.0
367.5
43.2
410.7
482.7
0.18
2.81
Mobile
Disposal site,
1984 k$
equipment Pond Landfill
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
8.3
3.6
0.5
3.4
18.9
0
0
221.0
4.2
259.9
2,691.8
155.9
2,847.7
3,107.6
1.13
18.11
Total
222.8
3.6
0.5
3.4
18.9
0.5
86.5
553.0
58.8
948.0
3,972.2
516.6
4,488.8
5,436.8
1.98
31.68
-------
TABLE B-5. MODULAR CAPITAL INVESTMENT BY TYPE OF EQUIPMENT
BASE CASE 3, HOLDING PONDS AND LANDFILL OF NONHARDENING ASH
CD
00
Equipment, 1982 k$
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities,
and miscellaneous
Total direct investment
Total indirect investment
Contingency
Total fixed investment
Other capital charges
Total depreciable
investment
Land
Working capital
Total capital investment
$/kW
Hoppers
773
647
1,420
57
1,477
369
185
2,031
480
2,511
0
80
2,591
5.18
Process
480
728
1,208
48
1,256
314
156
1,726
408
2,134
0
215
2,349
4.70
Pipelines
0
352
352
14
366
92
46
504
118
622
0
76
698
1.40
Mobile
equipment
1,208
0
1,208
48
1,256
0
0
1,256
0
1,256
0
126
1,382
2.76
Disposal
1982
site,
k$
Pond Landfill
0
3,142
3,142
126
3,268
522
379
4,169
650
4,819
510
53
5,382
10.76
0
1,863
1,863
75
1,938
484
242
2,664
416
3,080
550
97
3,727
7.45
Total
2,461
6,732
9,193
368
9,561
1,781
1,008
12,350
2,072
14,422
1,060
647
16,129
32.26
-------
00
VD
TABLE B-6. MODULAR ANNUAL REVENUE REQUIREMENTS BY TYPE OF EQUIPMENT
BASE CASE 3, HOLDING PONDS AND LANDFILL FOR NONHARDENING ASH
Equipment, 1984 k$
Annual revenue category
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
Utilities
Water
Electricity
Diesel fuel
Maintenance
Sampling and analysis
Contracted ash pumping
Total direct costs
Indirect Costs
Capital charges
Levelized annual capital charges
Plant and administrative overheads
Total indirect costs
Hoppers
84.2
0
0
0
0
118.0
0
0
202.2
380.9
121.3
502.2
Total annual revenue requirements 704. A
Mills/kWh
$/ton dry ash
0.25
4.10
Process
110.8
0
6.9
46.5
0
100.6
65.7
0
330.5
345.3
166.2
511.5
842.0
0.31
4.91
Pipelines
3.0
0
0
0
0
18.3
0
0
21.3
102.6
12.8
115.4
136.7
0.05
0.80
Mobile
equipment
625.0
0
0
0
195.0
125.6
0
0
945.6
203.2
450.4
653.6
1,599.2
0.58
9.32
Disposal site,
1984 k$
Pond
2.0
3.6
0
0
0
65.4
2.1
182.7
255.8
791.2
153.5
944.7
1,200.5
0.44
7.00
Landfill
66.0
10.7
0
0
0
58.1
2.1
0
136.9
547.8
82.1
629.9
766.8
0.28
4.47
Total
891.0
14.3
6.9
46.5
195.0
486.0
69.9
182.7
1,892.3
2,371.0
986.3
3,357.3
5,249.6
1.91
30.59
-------
TABLE B-7. MODULAR CAPITAL INVESTMENT BY TYPE OF EQUIPMENT
BASE CASE 4, DIRECT LANDFILL OF NONHARDENING ASH
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities,
and miscellaneous
Total direct investment
Total indirect investment
Contingency
Total fixed investment
Other capital charges
Total depreciable
investment
Land
Working capital
Total capital investment
$/kW
Hoppers
773
647
1,420
57
1,477
369
185
2,031
480
2,511
0
80
2,591
5.18
Equipment,
1982 k$
Process Pipelines
1,828
1,639
3,467
139
3,606
901
450
4,957
1,169
6,126
0
259
6,385
12.77
0
75
75
3
78
20
10
108
25
133
0
8
141
0.28
Mobile
equipment
682
0
682
27
709
0
0
709
0
709
0
71
780
1.56
Disposal site,
1982 k$
Pond Landfill
0
2,433
2,433
97
2,530
632
316
3,478
543
4,021
710
125
4,856
9.71
Total
3,283
4,794
8,077
323
8,400
1,922
961
11,283
2,217
13,500
710
543
14,753
29.51
-------
TABLE B-8. MODULAR ANNUAL REVENUE REQUIREMENTS BY TYPE OF EQUIPMENT
BASE CASE 4, DIRECT LANDFILL OF NONHARDENING ASH
Equipment^ 1984 k$
Disposal site,
Mobile 1984 k$
Annual revenue category
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
Utilities
Water
Electricity
Diesel fuel
Maintenance
Sampling and analysis
Total direct costs
Indirect Costs
Capital charges
Levelized annual capital charges
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
Hoppers
84.2
0
0
0
0
118.0
0
202.2
380.8
121.3
502.2
704.4
0.25
4.10
Process
110.8
10.7
0.1
27.5
0
283.3
27.8
460.2
937.0
259.6
1,196.6
1,656.8
0.60
9.65
Pipelines
1.5
0
0
0
0
3.9
0
5.4
22.3
3.2
25.5
30.9
0.01
0.18
equipment Pond
529.5
0
0
0
122.4
70.9
0
722.8
114.7
360.2
474.9
1,197.7
0.44
6.98
Landfill
66.0
10.8
0
0
0
75.9
4.2
156.9
713.7
94.1
807.8
964.7
0.35
5.62
Total
792.0
21.5
0.1
27.5
122.4
552.0
32.0
1,547.5
2,168.5
838.5
3,007.0
4,554.5
1.66
26.54
-------
TABLE B-9. MODULAR CAPITAL INVESTMENT BY TYPE OF EQUIPMENT
BASE CASE 5, DIRECT LANDFILL OF SELF-HARDENING ASH
vo
M
Equipment, 1982 k$
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities,
and miscellaneous
Total direct investment
Total indirect investment
Contingency
Total fixed investment
Other capital charges
Total depreciable
investment
Land
Working capital
Total capital investment
$/kW
Hoppers
666
557
1,223
49
1,272
318
159
1,749
413
2,162
0
69
2,231
4,46
Process
1,538
1,358
2,896
116
3,012
753
376
4,141
980
5,121
0
255
5,376
10.75
Pipelines
0
75
75
3
78
20
10
108
25
133
0
10
143
0.29
Mobile
equipment
734
0
734
29
763
0
0
763
0
763
0
76
839
1.68
Disposal site,
1982 k$
Pond Landfill
0
2,037
2,037
81
2,118
530
266
2,914
455
3,369
580
105
4,054
8.11
Total
2,938
4,027
6,965
279
7,244
1,622
811
9,677
1,873
11,550
580
515
12,645
25.29
-------
TABLE B-10. MODULAR ANNUAL REVENUE REQUIREMENTS BY TYPE OF EQUIPMENT
BASE CASE 5, DIRECT LANDFILL OF SELF-HARDENING ASH
vo
OJ
Equipment, 1984 k$
Disposal site,
Mobile 1984 k$
Annual revenue category
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
Utilities
Water
Electricity
Diesel fuel
Maintenance
Sampling and analysis
Total direct costs
Indirect Costs
Capital charges
Levelized annual capital charges
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
Hoppers
84.2
0
0
0
0
101.8
0
186.0
328.0
111.6
439.6
625.6
0.23
4.77
Process Pipelines
110.8
75.1
0.1
18.8
0
230.5
27.8
463.1
789.2
266.5
1,055.7
1,518.8
0.55
11.57
1.5
0
0
0
0
3.9
0
5.4
22.3
3.2
25.5
30.9
0.01
0.23
equipment Pond
595.5
0
0
0
110.6
76.3
0
782.4
-
123.3
403.1
526.4
1,308.8
0.48
9.97
Landfill
66.0
10.7
0
0
0
63.5
4.2
144.4
595.9
86.6
682.5
826.9
0 30
6.30
Total
858.0
85.8
0.1
18.8
110.6
476.0
32.0
1,581.3
1,858.7
871.1
2,729.8
4,311.1
1.57
32.84
-------
TABLE B-ll. MODULAR CAPITAL INVESTMENT BY PROCESS AREA
BASE CASE 1, DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Direct _InvestTnent
Material cost
Installation cost
Installed cost
Services, utilities, miscellaneous
Total direct investment
Indirect Investment
Engineering design and supervision
Architect and engineering
Construction expense
Contractor fees
Total indirect investment
Contingency
Total fixed investment
Other Capital Charges
Allowance for startup and
mo dificati on s
Interest during construction
Total depreciable investment
Land
Working capital
Total capital investment
$/kW
Flv nsh process areas, 1982 k$
Elec-
tion
706
487
1,193
48
1,241
75
37
124
75
311
155
1,707
137
268
2,112
0
225
2,3:.7
4.67
Transpor-
tation to
disposal
site
44
871
915
37
952
58
28
95
58
239
119
1,310
105
203
1,618
0
173
1,791
3.58
Disposal
site
8,509
8,509
340
8,849
176
90
708
441
1,415
1,026
11,290
0
1,762
13,052
1,560
36
14,648
29.30
Water
treatment
and
recycle
12
42
54
2
56
3
2
6
3
14
7
77
6
12
95
0
10
105
0.21
Subtotal
762
9,909
10,671
427
11 ,098
312
157
933
577
1,979
1.307
14,384
248
2,245
16,877
1,560
444
18,881
37.76
Collec-
! ion
386
435
821
33
854
51
25
85
51
212
107
1,173
94
183
1,450
0
74
1,524
3.05
Transpor-
i .• ! ion to
disposal
site
110
841
951
38
989
59
30
99
59
247
123
1,359
108
212
1,679
0
86
1,765
3.53
ash proces
Disposal
site
2,127
2,127
85
2,212
44
22
177
111
354
257
2,823
0
440
3,263
390
9
3,662
7.32
s areas, 1982 kS
Water
treatment
and
recycle
3
11
14
1
15
1
0
2
1
4
2
21
2
3
26
0
2
28
0.06
Subtotal
499
3,414
3,913
157
4,070
155
77
363
222
817
489
5,376
204
838
6,418
390
171
6,979
13.96
Total
direct
capital
investment
1,261
13,323
14,584
584
15,168
467
234
1,296
799
2,796
1L796
19,760
452
_i_083
23,295
1,950
25,860
51.72
-------
TABLE B-12. MODULAR ANNUAL REVENUE REQUIREMENTS BY PROCESS AREA
BASE CASE 1, DIRECT PONDING OF NONHARDENING ASH WITHOUT WATER REUSE
Ul
Fly ash process areas,
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
Utilities
Water
Electricity
Maintenance
Process
Ponds
Sampling and analysis
Total direct costs
Indirect Costs
Levelized annual capital charge
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
Collec-
tion
90.0
0
0
30.5
100.0
_
2.1
222.6
343.5
115.3
458.8
681.4
0.25
4.96
Transpor-
tation to
disposal
site
9.0
0
5.5
10.3
57.0
_
0
81.8
263.3
39.6
302.9
384.7
0.14
2.80
1984 k$
Water
treatment
Disposal and
site recycle
6.4
0
0
0.5
-
177.0
2.1
186.0
2,153.3
111.3
2,264.6
2,450.6
0.89
17.85
0.2
2.9
0
0.7
4.0
_
16.8
24.6
15.4
14.3
29.7
54.3
0.02
0.40
Bottom ash process areas,
Subtotal
105.6
2.9
5.5
42.0
161.0
177.0
21.0
515.0
2,775.5
280.5
3,056.0
3,571.0
1.30
26.01
Collec-
tion
49.5
0
0
7.8
68.0
-
2.1
127.4
224.0
71.7
295.7
423.1
0.15
12.32
Transpor-
tation to
disposal
site
49.5
0
1.4
10.9
57.0
-
0
118.9
259.5
64.0
323.5
442.4
0.17
12.89
Water
treatment
Disposal and
site recycle
1.5
0
0
0.2
-
44.0
2.1
47.8
538.3
28.6
566.9
614.7
0.22
17.92
0.1
0.7
0
0.2
1.0
-
16.8
18.8
4.1
11.2
15.3
34.1
0.01
0.99
1984 k$
Total
annual
revenue
Subtotal requirements
100.7
0.7
1.4
19.1
126.0
44.0
21.0
312.9
1,025.9
175.5
1,201.4
1,514.3
0.55
44.12
206. 3
3.6
6.9
61.1
287.0
221.0
42.0
827.9
3,801.4
456.0
4,257.4
5,085.3
1.85
29.63
-------
TABLE B-13. MODULAR CAPITAL INVESTMENT BY PROCESS AREA
BASE CASE 2, DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Fly ash process areas, 1982
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities, miscellaneous
Total direct investment
Indirect Investment
Engineering design and supervision
Architect and engineering
Construction expense
Contractor fees
Total indirect investment
Contingency
Total fixed investment
Other Capital Charges
Allowance for startup and
modifications
Interest during construction
Total depreciable investment
Land
Working capital
Total capital investment
$/kW
Collec-
tion
706
487
1,193
48
1,241
75
37
124
311
155
1,707
137
268
2,112
0
225
2,337
4.67
- Transpor-
tation to
disposal Disposal
site site
44
871
915
952
58
28
95
58
239
119
1,310
105
203
1,618
0
173
1,791
3.58
8,509
8,509
340
8,849
176
90
708
441
1,415
1,026
11,290
0
1,762
13,052
1,560
36
14,648
29.30
kS
Water
treatment
and
recv, le Subtotal
154
406
560
22
582
34
18
58
34
144
73
799
63
124
986
0
39
1,025
2.05
904
10,273
11,177
447
11,624
343
173
985
608
2,109
1,373
15,106
305
2,357
17,768
1,560
473
19,801
39.60
Bottom ash process areas,
Collec-
tion
3i,6
4J5
821
854
51
25
85
51
212
107
1,173
94
183
1,450
0
74
1,524
3.05
Transpor-
tation to
disposal
site
841
951
38
989
59
30
99
59
247
123
1,359
108
212
1,679
0
86
1,765
3.53
Disposal
site
2,127
2,127
85
2,212
44
22
177
111
354
257
2,823
0
440
3,263
390
9
3,662
7.32
Water
treatment
and
recycle
40
101
141
6
147
10
4
15
10
39
19
205
17
32
254
0
16
270
0.54
1982 k$
Subtotal
536
3,504
4,040
162
4,202
164
81
376
231
852
506
5,560
219
867
6,646
390
185
7,221
14.44
Total
direc t
capital
inves tmen t
1 ,440
13,777
15,217
609
15,826
507
254
1,361
839
2,961
1,879
20,666
524
3,224
24,414
1,950
658
27,022
54.04
-------
VO
TABLE B-14. MODULAR ANNUAL REVENUE REQUIREMENTS BY PROCESS AREA
BASE CASE 2, DIRECT PONDING OF NONHARDENING ASH WITH WATER REUSE
Fly ash process areas
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
93% limestone
Commercial lime
Sodium carbonate
Utilities
Water
Electricity
Maintenance
Process
Ponds
Sampling and analysis
Total direct costs
Indirect Costs
Levelized annual capital charge
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
Collec-
tion
90.0
0
-
-
-
0
30.5
100.0
-
2.1
222.6
343.5
115.3
458.8
681.4
0.25
4.96
Transpor-
tation to
disposal
site
9.0
0
-
-
-
0.4
10.3
57.0
-
0
76.7
263.3
39.6
302.9
379.6
0.14
2.77
Disposal
site
6.4
0
-
-
-
0
0.5
-
177.0
2.1
186.0
2,153.3
111.3
2,264.6
2,450.6
0.89
17.85
, 1984 k$
Water
treatment
and
recycle
13.4
2.9
0.4
2.7
15.1
0
21.0
39.5
-
25.2
120.2
150.6
59.5
210.1
330.3
0.12
2.41
Bottom ash process areas.
Subtotal
118.8
2.9
0.4
2.7
15.1
0.4
62.3
196.5
177.0
29.4
605.5
2,910.7
325.7
3,236.4
3,841.9
1.40
27.99
Collec-
tion
49.5
0
-
_
-
0
7.8
68.0
_
2.1
127.4
224.0
71. 7
295.7
423.1
0.15
12.32
Transpor-
tation to
disposal
site
49.5
0
-
_
-
0.1
10.9
57.0
_
0
117.5
259.5
63.9
323.4
440.4
0.17
12.85
Disposal
site
1.6
0
-
-
-
0
0.2
-
44.0
2.1
47.9
538.3
28.6
566.9
614.8
0.22
17.92
Water
treatment
and
recycle
3.4
0.7
0.1
0.7
3.8
0
5.3
10.5
-
25.2
49.7
39.7
26.7
66.4
116.1
0.04
3.38
, 1984 k$
Total
annual
revenue
Subtotal requirements
104.0
0.7
0.1
0.7
3.8
0.1
24.2
135.5
44.0
29.4
342.5
1,061.5
190.9
1,252.4
1,594.9
0.58
46.47
222.8
3.6
0.5
3.4
18.9
0.5
86.5
332.0
221.0
58.8
948.0
3,972.2
516.6
4,488.8
5,436.8
1.98
31.68
-------
00
TABLE B-15. MODULAR CAPITAL INVESTMENT BY PROCESS AREA
BASE CASE 3, HOLDING PONDS AND LANDFILL OF NONHARDENING ASH
Fly ash process areas, 1982 k$
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities, miscellaneous
Total direct investment
Indirect Investment
Engineering design and supervision
Architect and engineering
Construction expense
Contractor fees
Total indirect investment
Contingency
Total fixed investment
Other Capital Charges
Allowance for startup and
modifications
Interest during construction
Total depreciable investment
Land
Working capital
Collec-
tion
706
489
1,195
48
1,243
75
37
124
75
311
_155
1,709
137
269
2,115
0
225
Transpor-
tation to
disposal
site
604
356
960
38
998
25
12
41
25
103
51
1,152
45
88
1,285
0
_J_iZ
Disposal
site
334
4,025
4,359
174
4,533
144
74
367
223
808
500
5,841
0
854
6,695
848
77
Water
treatment
and
recycle Subtotal
24
84
108
5
113
7
3
11
7
28
14
155
12
24
191
0
_25
1,668
4,954
6,622
265
6,887
251
126
543
_?3.1
1 ,250
720
8,857
194
1,235
10,286
848
__494
Collec-
tion
370
426
796
32
828
50
25
83
50
208
104
1 .140
91
178
1,409
0
72
Bottom ash process areas,
Transpor-
tation to
disposal
site
333
347
680
27
707
28
14
47
28
117
59
883
53
101
1,037
0
58
Disposal
site
84
980
1,064
43
1,107
36
18
89
55
198
121
1,426
0
210
1,636
212
20
Water
treatment
and
recycle
6
25
31
1
32
2
1
3
2
8
4
44
3
7
54
0
J
1982 k$
Subtotal
793
1,778
2,571
103
2,674
116
58
222
135
531
288
3,493
147
496
4,136
212
153
Total
direct
capital
investment
2,461
6,732
9,193
368
9,561
367
184
7f5
465
1,781
1,008
12,350
341
1,731
14,422
1,060
647
Total capital investment 2,340 1,452 7,620 216 11,628 1,481 1,095 1,868 57 4,501 16,129
S/kW 4.67 2.90 15.26 0.43 23. 2C, 2.96 2.19 3.74 0.11 9.00 32.26
-------
TABLE B-16. MODULAR ANNUAL REVENUE REQUIREMENTS BY PROCESS AREA
BASE CASE 3, HOLDING PONDS AND LANDFILL OF NONHARDENING ASH
Fly ash process areas
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
Utilities
Water
Electricity
Diesel fuel
Maintenance
Process
Ponds + landfill
Sampling and analysis
Contracted ash pumping
Total direct costs
Indirect Costs
Levelized annual capital charge
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
Collec-
tion
90.0
0
0
28.7
0
100.0
_
2.1
-
220.8
344.0
115.3
459.3
680.1
0.25
4.95
Transpor-
tation to
disposal
site
299
5
1
84
86
182
664
213
340
554
1,218
0.
8.
.0
0
.5
.3
.3
.0
_
0
.7
.8
.4
.6
.0
.8
44
88
Disposal
site
264
1
71
35
98
4
475
1,120
241
1,361
1,837
0.
13.
.0
0
0
.1
.7
.8
.9
.2
-
.7
.1
.7
.8
.5
67
39
, 1984 k$
Water
treatment
and
recycle
0
11
0
8
29
50
31
29
61
111
0.
0.
.4
.4
0
.7
0
.0
_
.7
-
.2
.8
.7
.5
.7
04
81
Subtotal
653
11
5
37
156
229
98
36
182
1,411
1,709
727
2,436
3,848
1.
28.
.4
.4
.5
.8
.0
.8
.9
.0
.7
.5
.3
.3
.6
.1
40
03
Collec-
tion
49
3
66
2
120
217
70
288
409
0.
11.
.5
0
0
.3
0
.0
_
.1
-
.9
. 7
.6
.3
.2
15
92
Bottom ash
Transpor-
tation to
disposal
site
121
1
5
24
54
207
161
105
266
473
0.
13.
.9
0
.4
.0
. 7
.0
_
0
-
.0
.0
.5
.5
.5
17
79
process areas ,
Disposal
site
66
0
14
10
24
4
119
274
62
337
456
0.
13.
.0
0
0
.3
.3
.2
.1
.2
-
.1
.6
.7
.3
.4
17
31
Water
treatment
and
recycle
0
2
0
3
27
33
8
20
28
62
0.
1.
.2
.9
0
.2
0
.0
_
.5
-
.8
.4
.2
.6
.4
02
82
, 1984 k$
Total
annual
revenue
Subtotal requirements
237
2
I
8
39
.6
.9
.4
.8
.0
133.2
24
33
480
661
259
920
1,401
0.
40.
.1
.8
-
.8
.7
.0
.7
.5
51
84
891.0
14.3
6.9
46.5
195.0
363.0
123.0
69.9
182.7
1,892.3
2,371.0
986. 3
3,357.3
5,249.6
1.91
30.59
-------
TABLE B-17. MODULAR CAPITAL INVESTMENT BY PROCESS AREA
BASE CASE 4, DIRECT LANDFILL OF NONHARDENING ASH
! M
t O
o
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities, miscellaneous
Total direct investment
Indirect Investment
Engineering design and supervision
Architect and engineering
Construction expense
Contractor fees
Total indirect investment
Contingency
Total fixed investment
Other Capital Charges
Allowance for startup and
modifications
Interest during construction
Total depreciable investment
Land
Working capital
Total capital investment
$/kW
Collec-
tion
834
566
1,400
56
1,456
87
44
146
87
364
182
2,002
160
312
2,474
0
260
2,734
5.47
Fly ash
process areas, 1982 k$
Transpor-
tation to
disposal Disposal
site site
940
576
1,516
61
1,577
81
40
136
81
338
170
2,085
149
291
2,525
0
57
2,582
5.16
334
1,946
2,280
91
2,371
124
61
197
124
506
252
3,129
0
434
3,563
568
100
4,231
8.46
Water
treatment
and
recycle Subtotal
12
42
54
2
56
3
2
6
_J3
14
7
77
6
12
95
0
10
105
0.21
2,120
3,130
5,250
210
5,460
295
147
485
295
1,222
611
7,293
315
1,049
8,657
568
427
9,652
19.32
Collec-
tion
386
435
821
33
854
51
25
85
51
212
107
1,173
94
183
1,450
0
74
1,524
3.05
Bottom ash process areas, 1982 k$
Transpor-
tation to
disposal Disposal
site site
558
490
1,048
42
1,090
62
31
104
62
259
129
1,478
114
222
1,814
0
10
1,824
3.65
84
487
571
23
594
30
16
53
30
129
64
787
0
110
897
142
25
1,064
2.11
Water
treatment
and
recycle Subtotal
135
252
387
15
402
24
12
40
24
100
50
552
44
86
682
0
7
689
1.38
1,163
1,664
2,827
113
2,940
167
84
282
167
700
350
3,990
252
601
4,843
142
116
5,101
10.19
Total
direct
capital
investment
3,283
4,794
8,077
323
8,400
462
231
767
462
1,922
961
11,283
567
1,650
13,500
710
543
14,753
29.51
-------
TABLE B-18. MODULAR ANNUAL REVENUE REQUIREMENTS BY PROCESS AREA
BASE CASE 4, DIRECT LANDFILL OF NONHARDENING ASH
N>
Fly ash process areas.
Direct Costs
Conversion costs
Operating labor
Process reagents
H2S04 (100% equivalent)
Utilities
Water
Electricity
Diesel fuel
Maintenance
Process
Landfills
Sampling and analysis
Total direct costs
Indirect Costs
Levelized annual capital charge
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
Collec-
tion
90.0
0
0
16.1
0
116.0
-
2.1
224.2
401.8
124.9
526.7
750.9
0.27
5.46
Transpor-
tation to
disposal
site
114.4
0
0.1
2.5
26.1
129.0
-
0
272.1
379.6
146.0
525.6
797.7
0.29
5.81
, 1984 k$
Water
treatment
Disposal and
site recycle
316
0
71
28
60
2
481
622
245
867
1,348
0.
9.
.8
0
0
.8
.7
.9
.7
.1
.0
.0
.1
.1
.1
50
83
0.2
8.6
0
0.7
0
4.0
-
13.0
26.5
15.4
15.5
30.9
57.4
0.02
0.42
Bottom ash
Subtotal
521
8
0
20
97
277
60
17
1,003
1,418
531
1,950
2,954
1.
21.
.4
.6
.1
.1
.8
.9
.7
.2
.8
.8
.5
.3
.1
08
52
Collec-
tion
49
4
68
2
124
224
71
295
419
0.
12.
.5
0
0
.4
0
.0
-
.1
.0
.0
.7
.7
.7
15
23
Transpor-
tation to
disposal
site
75
2
10
83
171
268
95
363
534
0.
15.
.9
0
0
.4
.2
.0
-
0
.5
.0
.3
.3
.8
19
58
process areas,
Disposal
site
79
0
14
15
15
2
126
156
67
223
349
0.
10.
.2
0
0
.2
.3
.2
.2
.1
.2
.4
.0
.4
.6
13
19
Water
treatment
and
recycle
66
12
0
32
10
122
101
73
174
296
0.
8.
.0
.9
0
.4
0
.0
-
.7
.0
.3
.0
.3
.3
11
63
1984 k$
Total
annual
revenue
Subtotal requirements
270
12
0
7
24
198
15
14
543
749
307
1,056
1,600
0.
46.
.6
.9
.0
.4
.5
.2
.2
.9
.7
.7
.0
.7
.4
58
63
792
21
0
27
122
476
75
32
1,547
2,168
838
3,007
4,554
1.
26.
.0
.5
.1
.5
.4
.1
.9
.0
.5
.5
.5
.0
.5
66
54
-------
to
O
TABLE B-19. MODULAR CAPITAL INVESTMENT BY PROCESS AREA
BASE CASE 5, DIRECT LANDFILL OF SELF-HARDENING ASH
Fly ash process areas, 1982 k$
Direct Investment
Material cost
Installation cost
Installed cost
Services, utilities, miscellaneous
Total direct investment
Indirect Investment
Engineering design and supervision
Architect and engineering
Construction expense
Contractor fees
Total indirect investment
Contingency
Total fixed investment
Other Capital Charges
Allowance for startup and
modifications
Interest during construction
Total depreciable investment
Land
Working capital
Total capital investment
$/kW
Collec-
tion
693
470
1,163
46
1,209
73
36
121
73
303
151
1,663
133
259
2,055
0
217
2,272
4.54
Transpor-
tation to
disposal
site
833
462
1,295
53
1,348
65
33
109
65
272
136
1,756
122
234
2,112
0
92
2,204
4.40
Disposal
site
350
1,630
1,980
79
2,059
102
51
171
102
426
212
2,697
0
364
3,061
464
84
3,609
7.23
Water
treatment
and
recycle Subtotal
12
41
53
2
55
3
2
7
3
15
7
77
6
12
95
0
10
105
0.21
1,888
2,603
4,491
180
4,671
243
122
408
243
1,016
506
6,193
261
869
7,323
464
403
8,190
16.38
Collec-
tion
339
363
702
28
730
44
22
73
44
183
91
1,004
80
157
1,241
0
63
1,304
2.61
Bottom ash process areas, 1982 k$
Transpor-
tation to
disposal
site
493
428
921
37
958
54
27
91
54
226
113
1,297
100
195
1,592
0
18
1,610
3.22
Disposal
site
88
407
495
20
515
26
13
40
26
105
55
675
0
91
766
116
21
903
1.80
Water
treatment
and
recycle Subtotal
130
226
356
14
370
22
11
37
22
92
46
508
41
79
628
0
10
638
1.28
1,050
1,424
2,474
99
2,573
146
73
241
146
606
305
3,484
221
522
4,227
116
112
4,455
8.91
Total
direct
capital
investment
2,938
4,027
6,965
279
7,244
389
195
649
389
1,622
811
9,677
482
1,391
11,550
580
515
12,645
25.29
-------
o
OO
TABLE B-20. MODULAR ANNUAL REVENUE REQUIREMENTS BY TYPE OF EQUIPMENT
BASE CASE 5, DIRECT LANDFILL OF SELF-HARDENING ASH
Fly ash process areas
Direct Costs
Conversion costs
Operating labor
Process reagents
H2SC>4 (100% equivalent)
Utilities
Water
Electricity
Diesel fuel
Maintenance
Process
Landfills
Sampling and analysis
Total direct costs
Indirect Costs
Levelized annual capital charge
Plant and administrative overheads
Total indirect costs
Total annual revenue requirements
Mills/kWh
$/ton dry ash
Collec-
tion
90.0
0
0
10.8
0
97.0
-
2.1
199.9
334.0
113.5
447.5
647.4
0.24
6.17
Transpor-
tation to
disposal
site
140.8
0
0
2
23
107
274
324
148
472
746
0.
7.
.1
.5
.6
.0
-
0
.0
.0
.7
.7
.7
26
11
, 1984 k$
Water
treatment
Disposal and
site recycle
343
0
64
34
50
2
496
530
258
788
1,284
0.
12.
.4
0
0
.7
.9
.2
.8
.0
.0
.5
.2
.7
.7
47
23
0
8
0
4
13
26
15
15
30
57
0.
0.
.2
.6
0
.7
0
.0
-
.0
. s
.4
.5
.9
.4
02
55
Subtotal
574
8
0
14
88
242
50
17
996
1,203
535
1,739
2,736
0.
26.
.2
.6
.1
.7
.5
.4
.8
.1
.4
.9
.9
.8
.2
99
06
Collec-
tion
49
2
58
2
112
191
65
257
369
0.
14.
.5
0
0
.5
0
.0
-
.1
.1
. 7
.8
.5
.6
13
07
Bottom ash
Transpor-
tation to
disposal
site
82.5
0
0
1.2
9.2
72.0
-
0
164.9
236.7
92.7
329.4
494.3
0.17
18.83
process areas
Disposal
site
85
0
12
11
12
2
124
132
67
199
324
0.
12.
.8
0
0
.1
.9
. 1
.7
.1
.7
.6
.0
.6
.3
12
35
Water
treatment
and
recycle
66.0
77.2
0
0.3
0
29.0
-
10.7
183.2
93.8
109.7
203.5
386.7
0.14
14.72
, 1984 k$
Total
annual
revenue
Subtotal requirements
283
77
4
22
170
12
14
584
654
335
990
1,574
0.
59.
.8
.2
0
.1
.1
.1
.7
.9
.9
.8
.2
.0
.9
56
97
858
85
0
18
110
412
63
32
1,581
1,858
871
2,729
4,311
1.
32.
.0
.8
.1
.8
.6
.<>
.5
.0
.3
.7
.1
.8
.1
57
84
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA- 600/7- 81-170
4. TITLE AND SUBTITLE
Economics of Ash Disposal
Power Plants
2:
at Coal-fired
7. AUTHOR(S)
F.M.Kennedy, A.C.Schroeder, and J.D. Veitch
9. PERFORMING ORGANIZATION NAME AND ADDRESS
TVA, Office of Power
Division of Energy Demonstrations and Technology
Muscle Shoals , Alabama 35660
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
3. RECIPIENT'S ACCESSION1 NO.
5. REPORT DATE
October 1981
6. PERFORMING ORGANIZATION
8. PERFORMING ORGANIZATION
TVA/OP/ELYT-81/34
10. PROGRAM ELEMENT NO.
11. CONTRACT /GRANT NO.
TAG-D9-E721-BI
CODE
REPORT NO.
13. TYPE OF REPORT AND PERIOD COVERED
Final; 8/79-3/81
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES IERL-RTP project officer is Julian W. Jones, Mail Drop
7606.
61, 919/
16. ABSTRACT
report gives results of an evaluation of the comparative economics of
utility ash disposal by five conceptual design variations of ponding and landfill for a
500-MW power plant producing 5 million tons of ash over the life-of-project. For a
basic pond disposal without water reuse , the total capital investment from hopper
collection through 1-mile sluicing and pond disposal is $52/kW (1982 S). Comparable
total system investment using trucking to a landfill is $30/kW. (All disposal site con-
struction costs were fully capitalized in both cases; this convention affects the com-
parison of annual revenue requirements.) First-year annual revenue requirements
for the ponding system are 1. 85 mills/kWh (1984 £); those for the landfill system are
lower (1. 66 mills /kWh). On the other hand, levelized annual revenue requirements
are 2.26 and 2.42 mills /kWh, respectively. Disposal site costs are the major ele-
ment in all types of disposal and constituted the major difference in cost between pone
and landfill disposal. Reuse of sluicing water and additional provisions for the dis-
posal of self -hardening (high calcium oxide) ash added relatively little to costs.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
Pollution Coal
Ashes Combustion
Disposal Ponds
Materials Handling Sluices
Economics Earth Fills
Electric Power Plants
18. DISTRIBUTION STATEMENT
Release to Public
b.lDENTIFIERS/OPEN ENDED TERMS
Pollution Control
Stationary Sources
Ash Disposal
19. SECURITY CLASS (This Report)
Unclassified
20. SECURITY CLASS (This page)
Unclassified
c. COSATI Field/Group
13B 21D
2 IB
14G 08H
13H 13M
05C 13C
10B
21. NO. OF PAGES
239
22. PRICE
EPA Form 2220-1 (9-73)
204
------- |