xvEPA
  TVA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-80-050
March 1980
Tennessee Valley Authority
Office of Power
Energy Demonstrations
and Technology
Muscle Shoals Al 35660
EDT-112
           Preliminary Economic
           Analysis of a Lime Spray
           Dryer FGD System

           Interagency
           Energy/Environment
           R&D Program  Report

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 This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
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                                     EPA-600/7-80-050
                                     EDT-112
                                             March 1980
Preliminary  Economic  Analysis
           of  a  Lime Spray
         Dryer  FGD System
                       by

              T.A. Burnett and W.E. O'Brien

                 TVA Office of Power
     Division of Energy Demonstrations and Technology
              Muscle Shoals, Alabama 35660
            Interagency Agreement No. D9-E721-BI
               Program Element No. INE827
            EPA Project Officer: Theodore G. Brna

          Industrial Environmental Research Laboratory
       Office of Environmental Engineering and Technology
             Research Triangle Park, NC 27711
                    Prepared for

         U.S. ENVIRONMENTAL PROTECTION AGENCY
             Office of Research and Development
                 Washington, DC 20460

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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. Environ-
mental Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
                                   ii

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                                 ABSTRACT
     A preliminary economic analysis of two flue gas desulfurization
(FGD) processes, one dry and one wet, were performed for a new 500-MW
power plant burning western coal having 0.7% sulfur, 9.7% ash, and a
heating value of 9,700 Btu/lb and meeting current new source performance
standards (70% S02 removal and 0.03 Ib/MBtu particulate emission).  The
generic lime spray dryer process used a baghouse for particulate collection,
while the wet limestone slurry process had an electrostatic precipitator
(ESP) for particulate control.  In addition to the coal noted, the final
report will include an economic evaluation for both a low- and a high-
sulfur eastern coal.

     Results of the preliminary analysis show that the capital investment
costs for the generic lime spray dryer process for S02 and particulate
removal are $132/kW while being $186/kW for the ESP-wet limestone
slurry combination.  First-year and levelized annual revenue requirements
are 6.20 and 8.55 mills/kW, respectively, for the dry FGD process; 8.55
and 11.71 mills/kWh, respectively, for the wet process.

     Sensitivity analyses indicate (1) delivered raw material costs do
not significantly affect the annual revenue requirements for either the
wet or dry process, (2) annual revenue requirements for the spray dryer
are insensitive to the raw material stoichiometry, and  (3) waste  disposal
for the wet process even with fixation is still more expensive than for
the generic lime spray dryer process.
                                   iii

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                                CONTENTS
Abstract	   iii
Figures	   vii
Tables	viii
Abbreviations and Conversion Factors 	    ix
Acknowledgements 	     x

Executive Summary  	    xi

Introduction 	     1

Conclusions	     4

Recommendations  	     5

Design and Economic Premises 	     6
  Design Premises  	     5
    Emission Standards  	     6
    Fuel	     7
    Power Plant Design  	     8
    Power Plant Operation   	     8
    Flue Gas Composition	     8
    Absorber Design   	     9
    Reheat	    10
    Raw Materials	    10
    Waste Disposal	    11
  Economic Premises   	    11
    Capital Costs  	    H
    Capital Investment  Estimates  	    14
    Annual Revenue Requirements   	    17

Process Background and  Description  	    19
  Generic Lime Spray  Dryer  Process  	    19
    Process Description 	    19
    Analysis of Processing  Subsections  	    23
  Limestone Slurry Process  	    28
    Process Description 	    28
    Analysis of Processing  Subsections  	    31

Economic Evaluation and Comparison  	    38
  Accuracy of Estimates  	    38
  Capital Investment  	    39
    Generic Lime Spray  Dryer Process  	    39
    Limestone Slurry  Process 	    41

                                     v

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    Comparison	    4^
  Annual Revenue Requirements	    /-
    Generic Lime Spray Dryer Process  	    42
    Limestone Slurry Process 	    45
    Comparison	    ^c
  Sensitivity Analysis 	    47
    Sensitivity to Raw Material Prices 	    ^
    Sensitivity to Raw Material Stoichiometry  	    49
    Sensitivity to Waste Disposal Costs  	    49

References	    52
                                   vi

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                                 FIGURES
Number

 S-l    Generic lime spray dryer process.  Block flow diagram .  .  .
 S-2    Limestone slurry process.  Block flow diagram 	
 S-3    Sensitivity of the first-year annual revenue require-
        ments to the delivered cost of the raw material	    Xxi
 S-4    Sensitivity of the first-year annual revenue require-
        ments to the raw material stoichiometry in the absorber .  .    xxi
   1    Generic lime spray dryer process.  Flow diagram 	     20
   2    Limestone slurry process.  Flow diagram 	     29
   3    Sensitivity of the first-year annual revenue require-
        ments to the delivered cost of the raw material	     48
   4    Sensitivity of the first-year annual revenue require-
        ments to the raw material stoichiometry in the absorber .  .     48
                                    vii

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                                 TABLES
Number                                                                Page

 S-l    Major Design Premises	       ..
 S-2    Base-Case Comparison of Capital Investments and Annual
        Revenue Requirements  	       ..
 S-3    Summary of the Total Capital Investments  	     ..
 S-4    Summary of First-Year Annual Revenue Requirements 	       .
   1    Contract Awards for Spray Dryer-Based FGD Systems 	       ^
   2    Coal Composition and Flow Rate  	
   3    Fly Ash Analysis	
   4    Base-Case Flue Gas Composition and Flow Rate  	
   5    Design Conditions for Absorber System Calculations   ....      1n
   6    Levelized Annual Capital Charges for Regulated Utility
        Financing	      .,
   7    Cost Indexes and Projections  	
   8    Projected 1984 Unit Costs for Raw Materials,  Labor,  and
        Utilities 	
   9    Generic  Lime Spray Dryer Process Material Balance 	      2i
  10    Generic  Lime Spray Dryer Process Base-Case Equipment
        List,  Description, and Cost	      2,
  11     Limestone Slurry Process Material Balance 	      »_
  12     Limestone Slurry Process Base-Case Equipment  List,
        Description,  and Cost	      _?
  13     Generic  Lime  Spray Dryer Process Total  Capital  Investment  .      40
  14    Limestone Slurry Process Total  Capital  Investment 	      42
  15    Base-Case Total  Direct Investments and  Total  Capital
        Investments	      ,,
  16    Summary  of the Total  Capital  Investments   	      /-
  17     Generic  Lime  Spray Dryer Process Annual Revenue Require-
        ments  	     44
  18     Limestone Slurry Process Annual  Revenue Requirements  ...     //:
  19     Base-Case Total  First-Year and Levelized  Annual Revenue
        Requirements   	
  20    Summary  of the Total  First-Year  Revenue Requirements   ...     /7
  21     Comparison of  Total Capital  Investment and First-Year
        Unit Revenue Requirements for the  Generic  Lime Spray
        Dryer  Process  at  Various  Raw Material Stoichiometries
                                  viii

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                   ABBREVIATIONS AND CONVERSION FACTORS
ABBREVIATIONS
   o
aftj     actual cubic feet              kg
Btu      British thermal unit           k&
°C       degrees Celsius                kW
dia      diameter                       kWh
ESP      electrostatic precipitator     lb
°F       degrees Fahrenheit             k
FD       forced draft                   M
FGD      flue gas desulfurization       min
ft       feet                           mol
ft/sec   feet per second                MW
g        gram                           ppm
gal      gallon                         sft3
gpm      gallons per minute             sec
gr       grain                          vol
hr       hour                           wt
ID       induced draft                  yr
in.      inch
               kilogram
               kiloliter
               kilowatt
               kilowatthour
               pound
               thousand (kilo)
               million (mega)
               minute
               mole
               megawatt (electrical)
               parts per million (volume)
               standard cubic  feet
               second
               volume
               weight
               year
CONVERSION FACTORS

To convert from English units

acres
British thermal units
degrees Fahrenheit minus 32
feet
square feet
cubic feet
cubic feet per minute
gallons (U.S.)
gallons per minute
grains per cubic foot
horsepower
inches
pounds (mass)
pounds per cubic foot
pounds (force) per square inch
miles
standard cubic feet per minute
 (60°F)
tons (short)3
         To metric units
hectares
kilocalories
degrees Celsius
centimeters
square meters
cubic meters
cubic meters per second
liters
liters per second
grams per cubic meter
kilowatts
centimeters
kilograms
kilograms per cubic meter
Pascals (Newton per square meter)
meters

normal cubic meters per hour (0°C)
metric tons
Multiply
   by

   0.405
   0.252
  0.5556
   30.48
  0.0929
 0.02832
0.000472
   3.785
 0.06308
   2.288
   0.746
    2.54
  0.4536
   16.02
    6895
    1609

  1.6077
  0.9072
a.  All tons, including tons of sulfur, are expressed in short tons.
                                     ix

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                            ACKNOWLEDGEMENTS
     Partial, support for this study was provided by the Department of
Energy by means of pass-through funds to the Environmental Protection
Agency.

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     PRELIMINARY ECONOMIC ANALYSIS OF A LIME SPRAY DRYER FGD SYSTEM
                            EXECUTIVE SUMMARY
     Dry-scrubbing flue gas desulfurization (FGD)  technology using a
concentrated solution or suspension of a reactive absorbent in a spray
dryer is a recent development in electric utility FGD.   It is receiving
extensive attention, at the present time, and contracts have been awarded
for nine commercial installations.  Much of this interest is due to some
potentially significant technical advantages over conventional wet FGD
technology—the process design is relatively simple; stack gas reheat
may be substantially reduced or eliminated, and the product is a dry
waste rather than a wet sludge.

     These dry scrubbers have one significant disadvantage—the use of
an expensive (relative to limestone) alkali absorbent,  either lime or
soda ash.  The raw material cost penalty for using lime or soda ash must
be offset by savings in capital charges and maintenance costs for spray
dryer systems to be economically competitive with the wet limestone
systems.  Minimizing these raw material costs is one of the reasons that
the first commercial utility applications of these systems are on boilers
fired with lignite and subbituminous coals.  Both of these types of
coals are normally low in sulfur and, therefore, the amount of expensive
alkali raw material to be consumed in the FGD system is minimized.  (In
fact, the average fuel sulfur level at the utility boilers currently
under contract is less than 1.0%.)  These fuels also produce a highly
alkaline ash which, if recycled through the spray dryer, can further
reduce makeup raw material requirements.

     Although capital investments and revenue requirements for these
processes have been estimated by various process vendors and compared
with a conventional wet limestone slurry process, no independent economic
comparisons based on comparable design and economic premises have been
published.  The purpose of this economic evaluation is to compare the
costs of the spray dryer FGD technology with those of the limestone
slurry process based on the technical and economic premises developed
jointly by the Environmental Protection Agency  (EPA) and the Tennessee
Valley Authority  (TVA).

     In addition  to the base-case evaluations,  sensitivity analyses of
raw material costs and stoichiometries on the annual revenue requirements
were performed.   The capital investment and annual revenue requirements
                                   xi

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 for the limestone slurry process with sludge  fixation by  the  IU Conversion
 Systems,  Incorporated (IUCS)  process  and  landfill  disposal were determined
 for comparison with the costs of pond disposal.


 DESIGN AND ECONOMIC PREMISES

 Design Premises

      Table S-l lists the major design premises  for this study.  The
 base-case power plant is a new,  500-MW coal-fired  power unit  located  in
 the Great Plains - Rocky Mountain region.   The  fuel  is a  subbituminous
 coal with a heating value of  9,700 Btu/lb  and containing  0.7% sulfur
 (dry basis),  9.7% ash,  and 16% moisture.   The boiler heat rate is 9,500
 Btu/kWh.


                      TABLE S-l.   MAJOR DESIGN PREMISES
             Item
                                                 Premise
Power plant


Operating schedule

Fuel

Base year

FGD waste disposal

S02 removal- efficiency
Particulate removal efficiency

SOo absorber redundancy
                                 New, Great Plains - Rocky Mountain
                                  region, 500-MW coal-fired boiler,
                                  9,500 Btu/kWh heat rate
                                 130,400 hr, 30-yr life, 5,500-hr first-
                                  year operation
                                 Subbituminous coal; 9,700 Btu/lb, 0.7%
                                  sulfur, 9.7% ash, 16% moisture
                                 Capital investment:  mid-1982
                                 Revenue requirements:  1984
                                 Limestone:  clay-lined pond
                                 Generic lime spray dryer:  landfill
                                 70%
                                 99.8% (0.03 Ib of particulates/MBtu
                                  heat input)
                                 33% (3 operating trains, 1 spare)
     The FGD unit includes all the equipment necessary to meet the
recent (June 1979) new source performance standards (NSPS) for both
particulate matter (0.03 Ib/MBtu heat input) and S02 (overall 70% removal
for low-sulfur coals).  The overall design for the generic lime spray
dryer system is based on vendor information, while the design of the
limestone slurry process is based on in-house data and previous evaluations
by TVA.
                                   xii

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Economic Premises

     The project is assumed to begin in mid-1980 with a 3-yr construction
period ending in mid-1983.  The midpoint of construction costs, and
therefore the basis for the capital investment costs, is mid-1982.  The
revenue requirements are based on 1984 costs.  Delivered costs for raw
materials are projected based on mid-1979 prices in the Great Plains -
Rocky Mountain region.  Labor rates for 1984 for this region are assumed
to be equivalent to those for a midwestern location and are projected
from current midwestern labor costs.

     Capital investment estimate is made up of direct investment, indirect
investment, and other capital charges.  The direct investment is based
on equipment lists and other installation costs  (such as piping, electrical,
instrumentation, etc.) are factored from the equipment costs.  Indirect
investment  (engineering design and supervision,  construction expense,
etc.) is estimated based on the direct investment.  Other capital costs
(allowance  for startup and modification, interest during construction,
etc.) are estimated from the total direct and indirect investment.
These preliminary capital investment estimates are normally considered
to have a -20% to +40% range of accuracy (i.e.,  in an actual application
of the generic lime spray dryer process for this 500-MW boiler the capital
investment  could range from 20% less to 40% more than the projected $132.3/kW)

     Two types of annual revenue requirements are projected—first year
and levelized.  Both are based on 5,500 hours of operation per year at
full load (about a 63% capacity factor) and both use a levelized capital
charge.  Levelized annual revenue requirements differ from first-year
annual revenue requirements in that they take into consideration the
time value  of money over the life of the FGD unit and are calculated
using a 10% discount factor, 6% inflation factor, and a 30-yr economic
life.
PROCESS BACKGROUND AND DESCRIPTION

Generic Lime Spray Dryer Process

     The generic lime spray dryer process  (Figure  S-l)  contains only  two
major equipment items, a spray dryer and a baghouse.  Most of  the  flue
gas  from the boiler passes untreated to the  spray  dryer where  it contacts
an atomized slurry of lime and recycled waste.   The  sulfur oxides  are
absorbed and react with the lime, and  fly  ash alkali if present, to form
calcium sulfite and calcium sulfate.   The  slurry concentration is  adjusted
so that the water injected into the spray  dryer  is insufficient to
saturate the flue gas and the resulting waste material  leaves  as dry
particulate matter entrained in the flue gas.
                                    xiii

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                                                                                                 STACK
                                  PARTIAL BYPASS
X
H-








BOILER

MATERIAL
HANDLING AND
FEED PREPARATION
4





'\
^ SOo jT fc P ARTICULATE
^ ABSORPTION ^ REMOVAL
„
W ^ 	 _
^^ WASTE STORAGE
1
^ GAS
~ HANDLING


^ WASTE DISPOSAL
    Figure S-l.  Generic lime spray  dryer  process.   Block flow diagram.

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     The remaining flue gas from the boiler (22% of the total gas rate)
bypasses the spray dryers and enters the flue gas ducts downstream of
the spray dryers but before entering the baghouse.  The system is designed
such that the overall SOo removal will meet the recently promulgated
(June 1979) NSPS (i.e., 70% removal for coal containing 0.7% sulfur).

     The calcium-based particulate matter formed in the spray dryer and
the fly ash from the boiler are removed in the baghouse, which is designed
to meet the NSPS for particulate matter (0.03 Ib/MBtu).  Part of the
waste material from the baghouse (both fly ash and calcium-based salts)
is temporarily stored in a hopper before trucking to the landfill.  The
remainder is reslurried and recycled to the spray dryer.

     The only other area is the lime preparation area where lime is
stored, slaked, and pumped to the spray dryers.  Surge capacity for both
the dry lime and the lime slurry is included.

Limestone Slurry Process

     The limestone slurry process (Figure S-2) is also a relatively
simple process containing only two major equipment items, a high-efficiency
electrostatic precipitator (ESP) and a venturi/spray tower wet scrubber.
Although ESP's are not normally considered a part of the limestone
slurry process, they have been included in this limestone slurry process
so that it can be compared with the generic lime spray dryer process.

     Flue gas from the boiler passes through the ESP for fly ash removal
to meet the NSPS.  (The fly ash from the ESP is trucked to the disposal
pond.)  The flue gas from the ESP is divided into two streams.  Most
(72%) of the flue gas enters the S02 scrubbers where 90% of  the entering
S02 is absorbed to achieve the overall 70% SC>2 removal required by  the
NSPS for the 0.7% sulfur coal.  The remaining  flue gas bypasses  the
scrubbers and enters the flue gas ducts after  the scrubber,  providing
sufficient heat to make reheating unnecessary.

     Part of the recirculating slurry in the absorption section  is  bled
off and pumped to the disposal pond.  The wet  calcium sulfite-sulfate
salts settle out as a 40%  (by weight) sludge,  and the supernate  is
recycled for reuse in the process.

     The major remaining processing area is  the limestone preparation
area where the makeup limestone is stored, crushed, milled,  and  slurried
before being added to the recirculating slurry.   Surge capacity  for both
dry limestone and the limestone slurry is included.


ECONOMIC EVALUATION AND COMPARISON

     Preliminary estimates of capital investment, first-year revenue
requirements, and levelized annual revenue requirements were prepared
for both the generic lime spray dryer process  and the limestone  slurry
process based on the design and economic premises.  These results  are
shown in Table S-2.
                                    xv

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                                                                      PARTIAL  BYPASS
                                                                "          ,
   BOILER
PARTICULATE
  REMOVAL
  GAS
HANDLING
                                                                                               STACK
                                                                       t
ABSORPTION
                                                                           I
                                                                          WASTE
                                                                         DISPOSAL
                                                                     MATERIAL HANDLING
                                                                            AND
                                                                     FEED PREPARATION
Figure  S-2.   Limestone  slurry process.   Block flow diagram.

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                TABLE S-2.  BASE-CASE COMPARISON OF CAPITAL

                INVESTMENTS AND ANNUAL REVENUE REQUIREMENTS
                                           Generic lime
                                            spray dryer
                                              process
       Capital investment (1982 $)
         M$
         $/kW
       Total first-year revenue require-
        ments (1984 $)
         M$
         mills/kWh
       Levelized annual revenue require-
        ments (1984 $)
         M$
         mills/kWh
 66.2
132.3
 17.04
  6.20
 23.52
  8.55
           Limestone
            slurry
            process
 93.2
186.4
 23.50
  8.55
 32.19
 11.71
     The capital investment for the generic lime spray dryer process is
$66.2M ($132.3/kW) in mid-1982 dollars.  The total direct investment
portion of the capital investment, which includes equipment costs and
installation expenses, accounts for $32.5M.  The major processing areas,
in terms of investment required, are particulate matter removal ($11.1M),
gas handling ($7.2M), and S02 absorption ($7.2M).  These areas alone
account for 78% of the direct investment.  The indirect investments
(engineering design and supervision, architect and engineering contractor,
etc.) are about $18.2M; the other capital charges (allowance for startup
and modifications, interest during construction, etc.) make up the
remaining $15.5M.

     The capital investment for the limestone slurry process is $93.2M
($186.4/kW) in mid-1982 dollars.  The total direct investment portion of
the capital investment accounts for $45.7M.  The major processing areas
in this total direct investment are S02 absorption ($13.7M), particulate
matter removal ($12.4M), and gas handling ($9.9M).  These three areas
account for about 79% of the direct investment.  The indirect investments
and the other capital charges account for $25.5M and $21.9M of the capital
investment respectively.

     The first-year and the levelized annual revenue requirements for
the generic lime spray dryer process are $17.OM (6.20 mills/kWh) and
$23.5M (8.55 mills/kWh) respectively.  The major component of these
revenue requirements is the levelized capital charges of $9.7M.  Other
important annual costs are maintenance ($1.9M), overheads ($1.8M), elec-
tricity ($1.5M), and lime ($1.0M).
                                  xvii

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      The first-year  and  the  levelized  annual  revenue  requirements  for
 the  limestone  slurry process are  $23.5M (8.55 mills/kWh) and  $32.2M
 (11.71  mills/kWh)  respectively.   Again,  the major  component of  these
 revenue requirements is  the  levelized  capital charges of $13.7M.   Other
 major annual costs are maintenance  ($3.5M), overheads ($3.0M),  and
 electricity  ($1.8M).

 Comparisons

      In terms  of both capital  investment and  first-year annual  revenue
 requirements,  the  base-case  generic lime spray dryer process  is sub-
 stantially lower in  cost than  the base-case limestone slurry  process as
 shown in Table S-2.  The capital  investment for the generic lime spray
 dryer process  is about 29% lower, and  the first-year annual revenue
 requirements are about 28% lower, than those  for the limestone  slurry
 process.

      If these  total  capital  investments are broken down into  individual
 investment areas as  shown in Table S-3, the reasons for the higher cost
 of the  limestone slurry process are apparent.  With the exception of the
material handling area and particulate matter handling and recycle area
 (which  the limestone slurry process does not have), the area  investments
 for the limestone slurry process are higher than those for the  generic
 lime spray dryer process.  In  fact the differences in only three areas,
 the SC>2 absorption, disposal area preparation, and gas-handling areas,
account for a $12.8M difference in direct investment, or about  $26.OM in
total capital investment when  the other capital charges are adjusted to
reflect the higher direct investment.

           TABLE S-3.  SUMMARY OF THE TOTAL CAPITAL INVESTMENTS




Investment area
Material handling
Feed preparation
Gas handling
S02 absorption
Particulate removal
Particulate handling
and recycle
Solids disposal
Disposal area preparation
Land
All other capital costs
Total capital investment
Total cost
Generic lime
spray dryer
process
2,443
599
7,190
7,173
11,133

1,425
379
321
515
34,993
66,171
, k$
Limestone
slurry
process
919
1,071
9,924
13,734
12,395

-
1,453
3,793
910
48,910
93,109

         Basis:
           TVA design and economic premises.

                                  xviii

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     The lower investment costs for the generic lime spray dryer process
in these three areas are primarily due to the use of the spray dryer
absorber.  The design of the generic lime spray dryer process precludes
the need for mist eliminators and the large recirculating slurry pumps
which are used in the SC^ absorption area of the limestone slurry process.
The higher land and disposal area preparation costs (i.e., pond construction)
for the limestone slurry process are due to the nature of the settled
sludge in the pond (i.e., the sludge in the pond is only 40% solids) in
contrast to the dry waste going to the landfill in the generic lime
spray dryer process.

     The first-year annual revenue requirements are broken down into
various annual costs in Table S-4.  Major cost differences between the
processes are costs for raw materials, maintenance, and levelized capital
charges.  The higher raw material cost for the generic lime spray dryer
process is due to the consumption of expensive lime ($102/ton) rather
than limestone ($8.50/ton).  Maintenance costs for the limestone slurry
process are substantially higher because of the need to recirculate
large amounts of limestone slurry through the process equipment.  Levelized
capital charges are higher for the limestone slurry process because of
the higher total capital investment required.
       TABLE S-4.  SUMMARY OF FIRST-YEAR ANNUAL REVENUE REQUIREMENTS
       Raw materials
       Operating labor and supervision
       Electricity
       Maintenance
       Levelized capital charges
       Other annual costs

            Total first-year revenue
            requirements
                                                Total cost, $
                                          Generic lime
                                           spray dryer
                                             process
 1,026,900
   948,800
 1,485,600
 1,939,400
 9,727,100
 1,912,600
              Limestone
               slurry
               process
   133,900
 1,321,600
 1,764,300
 3,464,700
13,698,800
 3,120,500
17,040,400   23,503,800
 SENSITIVITY ANALYSIS

 Sensitivity to  Raw Material  Cost

      The  generic  lime  spray  dryer  process  is  more  sensitive  to  changes
 in the  delivered  price of  the raw  material than the limestone slurry
 process.   Because of the low-sulfur coal used and  the low S02 removal
 requirement,  however,  cost changes from the base case do not significantly
                                   xix

-------
 change the economic results, as shown in Figure S-3.  The generic lime
 spray dryer process has lower first-year annual revenue requirements
 regardless of the raw material prices selected.

      The limestone slurry process, because of the low unit cost of
 limestone as well as the low-sulfur level in the coal and the low SO?
 removal requirement, is essentially insensitive to the delivered price
 of limestone.

 Sensitivity to Raw Material Stoichiometry

      Since the design Stoichiometry for the limestone slurry process is
 based on the results from actual low-sulfur coal applications,  only the
 base-case Stoichiometry for the limestone slurry process was evaluated.
 The generic lime spray dryer process,  however,  represents technology
 which has not  been demonstrated on a commercial scale and hence may
 change as this technology is developed further.  Therefore,  a range of
 raw material stoichiometries from 1.00 (-18.0%) to 1.46  (+19.7%) was
 evaluated.

      The  results of this sensitivity analysis are not significantly
 different from those previously discussed for the sensitivity to raw
 material  prices  (i.e.,  regardless  of what reasonable raw material Stoichio-
 metry is  used  for the  generic lime spray dryer  process,  the  generic lime
 spray dryer process has a lower first-year annual revenue requirement
 than the  base-case limestone slurry process)  as shown in Figure S-4.

 Sensitivity to Waste Disposal Costs

      Since  some  power plant  locations  do not  have sufficient  land available
 for ponding of the limestone slurry process waste,  the relative economics
 for a limestone  slurry  process with an alternative  disposal method,  the
 IUCS fixation  process,  were  also evaluated.   The  limestone slurry process
 up  to the point  at which the purge stream leaves  the scrubbers  is identical
 for both  cases.   For the base-case limestone  slurry  process,  the scrubbing
 waste is  simply  pumped  to  the pond and the supernate is  returned to  the
 process.  For  the limestone  slurry - IUCS fixation process, the  waste  is
 pumped to a thickener and  filter for dewatering, mixed with lime and  fly
 ash,  and  allowed  to set  up before  being hauled by truck  to an onsite
 landfill  for disposal.

      The  total capital  investment  for  this combination limestone  slurry -
 IUCS  pro.cess is  $91.4M  ($183/kW) in 1982  dollars or nearly $2.0M less
 than  the base-case limestone  slurry process with ponding.  This  decrease
 in  capital investment is due  to the substantially lower disposal  area
preparation costs and land requirements for the IUCS alternative.

      The  first-year and  the  levelized annual revenue requirements for
the limestone slurry - IUCS fixation process are $24.98M  (9.08 mills/kWh)
and $35.20M (12.80 mills/kWh) respectively.  These costs are about 6%
higher than those for the base case (i.e., with ponding)  primarily
because of the higher labor costs and related higher overhead costs.
                                   xx

-------
                   LIMESTONE COST, S/TON










X
X
M-









10.0

§ 9.0
1/5
rf
cn
2 8'°
W
a.
D
8'
Q£
g 7.0
Z
UJ

w
^ 6.0
i
>«
H
w
2
fc 5.0
4.0
5.00 8.50 12.00
1 1 1

~ Limestone slurry process


"— ~~"




- —



Generic 1 iine spray dryer process






i i i
10.0
g 9.0
en
*
g 8.0
M
1
M
K
P£
p 7-0
u
S
a:

5 6.0
f
H
t/3

fc 5.0

4.0
n

1 1 1 I 1


Limestone slurry process
_




_



	 B
Generic lime spray dryer process




— _

i i i i i

            75.00         102.00         125.00
                LIME COST (DELIVERED), $/TON

Figure  S-3.   Sensitivity  of the first-year
               annual revenue requirements  to
               the delivered  cost of the raw
               material.
            RAW MATERIAL STOICHIOMETRY, MOL ALKALI/MOL S02 ABSORBED

Figure  S-4.   Sensitivity  of the  first-year  annual
               revenue requirements  to the  raw material
               stoichiometry in the  absorber.

-------
 CONCLUSIONS AND RECOMMENDATIONS

 Conclusions

      For  a new,  500-MW power  unit  burning  a  0.7%  sulfur subbituminous
 coal,  the generic  lime spray  dryer process has  a  lower total capital
 investment and  lower  annual revenue requirements  than a comparable
 limestone slurry process.  These differences  in capital investment and
 annual revenue  requirements are larger  than  the uncertainty surrounding
 the  comparability  of  preliminary economic  estimates of this type  (+10%).
 Therefore,  for  the assumed design  and economic  premises the generic lime
 spray  dryer process appears to  have a significant economic advantage
 over a conventional limestone slurry process.

     For  these  design and economic premises,  the  generic lime spray
 dryer  process maintains  its economic advantage  over the limestone slurry
 process for all  ranges of raw material  costs  and  raw material stoichio-
 metries studied.   The generic lime spray dryer  process also has an
 economic  advantage over  a combined limestone  slurry - IUCS process for
 fixation  and landfill instead of ponding waste  disposal.

 Recommendations

     Since  only  a  single base-case application  of the generic lime spray
 dryer  process has  been considered  in this  study, a definitive economic
 analysis  of this process is suggested as the  logical next step.  Not
 only would  the accuracy of the  capital  investment and annual revenue
 requirements for the base case be  increased, but several case variations
 (power unit size,  sulfur level  in  the coal, S02 removal efficiency, for
 example)  could be  evaluated.

     Other areas which require additional  study (and which will be
evaluated in the final report  for  this project)  include:

   «  Generic soda ash spray dryer process for a low-sulfur subbituminous
      coal application.

   o  Generic lime spray dryer process for a low-sulfur eastern coal
      application.

   o  Generic lime spray dryer process for a high-sulfur  eastern coal
      application.
                                   xxii

-------
     PRELIMINARY ECONOMIC ANALYSIS OF A LIME SPRAY DRYER FGD SYSTEM
                               INTRODUCTION
     One of the recent developments in flue gas desulfurization (FGD),
the so-called dry scrubbing technology using a concentrated solution or
suspension (depending on whether the alkali material is sodium- or
calcium-based) of a reactive absorbent in a spray dryer, is currently
receiving a considerable amount of attention.  Much of this interest is
due to some potentially significant technical advantages over conventional
wet FGD technology (primarily lime or limestone slurry scrubbing).  In
particular, the process design is relatively simple and a dry waste,
rather than a wet sludge, is produced.

     Nine contracts have been awarded for these dry scrubbers (listed in
Table 1), six for commercial utility boilers and three for industrial
boilers.  With the exception of one utility boiler application which
uses a sodium-based system, the systems under contract use lime-based
spray dryer technology.  Of the six utility boiler applications, three
are lignite-fired boilers and three are fired with subbituminous coal.
All six of these boiler fuels are relatively low in sulfur (<1%) and
have a highly alkaline fly ash.  Two of the three industrial boiler
applications, on the other hand, involve eastern bituminous coals which
have higher sulfur levels and relatively low alkalinity in the fly ash.

     These dry scrubbers have one significant disadvantage—the use of
an expensive  (relative to limestone) alkali absorbent, either lime or
soda ash.  As long as the savings in capital charges and maintenance
costs for the spray dryer systems are higher than the raw material cost
penalty for lime or soda ash, the spray dryer systems will remain econom-
ically competitive with the wet limestone systems.  This is one of the
reasons that  the first commercial applications are on utility boilers
fired with lignite and subbituminous coals.  Since both of these types
of coals are normally low in sulfur, the amount of sulfur to be removed,
and hence the consumption of expensive alkali raw material in the FGD
system, is minimized.  (In fact, the average sulfur levels in the fuels
at the utility boilers currently under contract are all less than 1.0%
sulfur.)

-------
TABLE 1.  CONTRACT AWARDS FOR SPRAY DRYER-BASED FGD SYSTEMS

Installation
Utility Boiler
Coyote Unit 1
Antelope Valley Unit 1
Laramie River Unit 3
Stanton Unit 2
Springerville Unit 1
Springerville Unit 2
Rawhide Unit 1
Industrial Boiler
Strathmore Paper Co.
Celanese
University of Minnesota
Size,
gross MW
410
440
575
63
350
350
250
14e
22e
83e
Fuel
type (% S)
Lignite (0.78)
Lignite (0.68)
Subbituminous
Lignite (0.77)
Subbituminous
Subbituminous
Subbituminous
Bituminous (2.
Bituminous (1.
Subbituminous


(0.54)

(0.69)
(0.69)
(0.29)
0-2.5)
0-2.0)
(0.6-0.
S02 Alkali raw Startup
removal, % material date
50
62
85
73
61
61
70
75
70-80
7) 70
Soda ash
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
Lime
4/81
4/82
4/81
9/82
2/85
9/86
12/83
7/79
1/80
9/81
Vendor
RI/WF3
Joy/Niro
B&WC
R-Cd
Joy/Niro
Joy/Niro
Joy/Niro
Mikropul
RI/WF
Carborundum

a. Rockwell International/Wheelabrator-Frye.
b. Western Precipitation Division of Joy Manufacturing
c. Babcock and Wilcox.
d. Research-Cottrell.
e. Based on 2,900 aft
/MW.


Company /Niro

Atomizer, Inc.






-------
     Another advantage for the spray dryer processes associated with
these western coals is the relatively high alkalinity of the fly ash
from these coals.  Not only does this alkalinity react with sulfur in
the boiler and thus reduce the amount of sulfur removal required in the
FGD system, but the alkalinity in the fly ash also removes sulfur oxides
(SOX) from the flue gas in the spray dryer (if recycled) and thereby
decreases the consumption of makeup alkali raw material.

     Thus, in order to reflect the current utility market for these
spray dryer systems, the fuel chosen for this study is a low-sulfur
subbituminous coal containing a highly alkaline ash.

     Although capital investments and revenue requirements for these dry
scrubbing processes have been estimated by various process vendors and
compared with a conventional wet limestone slurry process, no independent
economic comparisons have been published.  The purpose of this study is
to make an economic comparison of a generic lime spray dryer process
with a conventional wet limestone slurry process using the same design
and economic premises.

     In addition to these base-case evaluations, a sensitivity analysis
is included in which the annual revenue requirements are calculated for
various raw material costs and stoichiometries.  The capital investment
and annual revenue requirements for an alternate limestone slurry process
with sludge fixation and landfill disposal are also included.

-------
                                CONCLUSIONS
     For a new, 500-MW power unit burning a 0.7% sulfur subbituminous
coal, the generic lime spray dryer process has a lower total capital
investment and lower annual revenue requirements than a comparable
limestone slurry process.  These differences in capital investment and
annual revenue requirements are larger than the uncertainty surrounding
the comparability of preliminary economic estimates of this type (+10%).
Therefore, for the assumed design and economic premises the generic lime
spray dryer process appears to have a significant economic advantage
over a conventional limestone slurry process.

     For these design and economic premises, the generic lime spray
dryer process maintains its economic advantage over the limestone slurry
process for all ranges of raw material costs and raw material stoichio-
metries studied.  The generic lime spray dryer process also has an
economic advantage over a combined limestone slurry - IUCS process for
fixation and landfill instead of ponding waste disposal.

-------
                             RECOMMENDATIONS
     Since only a single base-case application of the generic lime spray
dryer process has been considered in this study,  a definitive economic
analysis of this process is suggested as the logical next step.   Not
only would the accuracy of the capital investment and annual revenue
requirements for the base case be increased, but  several case variations
(power unit size, sulfur level in the coal, S02 removal efficiency, for
example) could be evaluated.

     Other areas which require additional study (and which will be
evaluated in the final report for this project) include:

   •  Generic soda ash spray dryer process for a low-sulfur subbituminous
      coal application.

   •  Generic lime spray dryer process for a low-sulfur eastern coal
      application.

   •  Generic lime spray dryer process for a high-sulfur eastern coal
      application.

-------
                         DESIGN AND ECONOMIC  PREMISES
      This  study  compares  the  economics  of  two  FGD  systems on an equitable
 basis using  conditions  that are  as  representative  as possible of projected
 industry conditions  and that  provide  a  clearly definable breakdown of
 costs into significant  and useful divisions.   The  premises used in this
 study have been  developed by  the Tennessee Valley  Authority (TVA), the
 U.S.  Environmental Protection Agency  (EPA), and others during similar
 economic evaluations made since  1967.   Criteria of the premises are
 designed to  establish efficiencies, process flow rates, and other
 operating  and  design conditions.  The economic premises are designed to
 represent  the  many factors affecting  costs.
DESIGN PREMISES

     The utility plant design and operation is based on Federal Energy
Regulatory Commission (FERC) historical data (1) and TVA experience.
The conditions used are representative of a typical modern boiler for which
FGD systems would most likely be considered.  An Upper Great Plains and
Rocky Mountain location typical of Wyoming, Colorado, Nebraska, and
North and South Dakota is used because the concentration of both low-
sulfur subbituminous coal supplies and power plants in this area make it
representative of the segment of the power industry most attracted to
the spray dryer FGD technology*

     Although the FGD design is assumed to be proven, in keeping with
current industry practice a redundant absorber train is provided to
maintain acceptable boiler availability.  In the integration of the
absorber system with the boiler systems, provision for turndown and
maintenance are limited to provision of a common plenum between the
systems with dampers to allow individual trains to be shut down.

Emission Standards

     New source performance standards (NSPS) established by EPA (2)
specify a maximum emission, based on heat input, of 0.03 Ib/MBtu for
particulate matter, 1.2 Ib/MBtu for S02, and 0.5 Ib/MBtu for NOX.   In
addition to meeting this maximum emission limit of 1.2 Ib/MBtu for SO?,
the NSPS also require that new plants must reduce the uncontrolled SO?
emissions from 70% to 90%, depending on the uncontrolled S02 emission
level.   For the low-sulfur subbituminous coal chosen in this study,  this
percentage S07 reduction is 70%.  In addition it is assumed that the

-------
boiler is designed to meet the 0.5 Ib/MBtu NOX standard and that the FGD
system includes all the process equipment needed to meet both the 0.03
Ib/MBtu particulate matter standard and the 70% S02 removal standard.

Fuel

     The coal premises are composites of many samples representing major
western coal production areas.  The subbituminous coal is assumed to
have a heating value of 9,700 Btu/lb and an ash content of 9.7% (both as
fired) and a sulfur content of 0.7% (dry basis).  The composition and
flow rates for the base-case conditions are shown in Table 2.  Although
fly ash compositions are not normally of great significance in specifying
a limestone FGD system, if the fly ash contains appreciable alkalinity
it can have a significant effect on the economics of dry FGD systems
which consume an expensive alkali raw material.  Because of the high
alkalinity of many western coals, a typical alkaline fly ash with the
composition shown in Table 3 is used.
                 TABLE 2.  COAL COMPOSITION AND FLOW RATE

Coal
component
C
H
0
N
S
Cl
Ash
H20
Wt %
as fired
57.00
3.90
11.50
1.20
0.59
0.10
9.70
16.00
Ib/hr
279,100
19,100
56,310
5,876
2,889
A90
47,500
78,350

                  Basis:
                    500-MW new coal-fired unit,  9,500
                    Btu/kWh,  9,700 Btu/lb heating value,
                    0.7%  sulfur in coal,  dry basis.

-------
                         TABLE 3.   FLY ASH ANALYSIS
                          Fly ash component    Wt
Si02
A120
Fe203
CaO
MgO
Na-,0
K20
Ti02
S03
Other
Total
32.2
17.4
6.0
20.0
4.7
1.7
0.5
1.0
15.3
1.2
100.0

Power Plant Design

     A single horizontal opposed, balanced-draft boiler for a 500-MW net
electrical output is used.  This net output does not include the power
requirements for the FGD system.  In contrast to some previous FGD
studies by TVA, particulate matter removal and disposal have been included
as part of the FGD unit rather than as part of the boiler because of the
nature of the dry sorbent processes, which collect fly ash and sulfur
salts simultaneously.

Power Plant Operation

     An operating life of 30 years and a total operating lifetime of
130,500 hours are used.  For this study a boiler capacity factor of
62.8% (equivalent to full load for 5,500 hr/yr) and a boiler heat rate
of 9,500 Btu/kWh are used.

Flue Gas Composition

     Flue gas compositions are the result of boiler design, fuel, and a
variety of operating conditions.  Combustion and emission conditions
used to determine flue gas composition are based on balanced-draft
boiler design and average values for the sulfur content of coal.   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.   These values reflect TVA operating experience with
horizontal, frontal-fired, coal-burning units.  It is assumed that 80%
of the ash present in coal is emitted as fly ash and 85% of the sulfur
in coal is emitted as SOX.  Three percent of the SOX emitted is assumed
to be SO^ and the remainder S02.   The base-case flue gas composition and
flow rates calculated for these conditions are shown in Table 4.

                                    8

-------
          TABLE 4.   BASE-CASE FLUE GAS  COMPOSITION AND  FLOW RATE
                Flue gas component    Volume,  %      Ib/hr
N2
°2
co2
so2
so3
NOX (as NO)
HC1
H20
Ash
73.09
5.39
12.24
0.04
-
0.03
0.01
9.20
-
3,887,000
327,200
1,023,000
4,760
184
1,590
504
314,600
38,000
                     Total            100.00     5,597,000
          Basis:
            500-MW new coal-fired unit,  9,500 Btu/lb heating
            value, 0.7% sulfur, dry basis, 1,754,000 aft^/min
            at 300°F.
Absorber Design

     Absorber design criteria are based on TVA operating experience,
general power industry practice, and information from process and equip-
ment vendors.  The generic lime spray dryer process is based on vendor
information.  The limestone process is based on TVA experience at the
Shawnee EPA Alkali Test Demonstration Facility, extensive power industry
experience with these processes, and vendor information.  Both the
generic lime spray dryer and the limestone slurry processes are fed from
a common plenum located downstream of the boiler air heaters.  Both of
these FGD processes consist of four parallel trains of absorbers of
which three are operating and one is a spare.  In addition, since only
70% S02 removal is required to meet the NSPS, part of the flue gas in
both processes is bypassed around the absorbers for reheat purposes.
The remaining flue gas passes through the absorbers where, depending on
the process, the S02 removal is 80% to 90%.  As the flue gas leaves the
absorber, the hot bypassed flue gas is mixed with the scrubbed flue gas
to obtain a 175 F recombined flue gas.

     The generic lime spray dryer process feeds a single baghouse.
Since the flue gas from these spray dryers is not saturated and does not
contain entrained liquid, mist eliminators are not required.  Induced-
draft (ID)  fans located between the baghouse and the stack are provided
to compensate for the assumed total pressure drop of 12 inches H20 for
the generic lime spray dryer process.

-------
      The limestone slurry process  is  provided with  high  efficiency
 (99.8%)  electrostatic  precipitators  (ESP)  for particulate matter removal,
 venturi  scrubber presaturators  before the  absorber,  and  chevron-type mist
 eliminators  after the  spray towers.   The mist eliminators reduce the
 moisture content of the  scrubbed gas  to 0.1%.   This  reduces  the reheating
 load,  decreases  deposition and  corrosion in  downstream equipment, and
 reduces  particulate matter emission.   A 16-inch 1^0  pressure drop is
 assumed  for  the  limestone slurry process,  and in contrast to the generic
 lime  spray dryer process which  uses ID fans, a  forced-draft  (FD) fan is
 included between the boiler plenum and each  venturi  scrubber to compensate
 for this pressure drop.   Operating conditions for the absorbers are
 shown  in Table 5.   These conditions are used for both the base-case and
 case variation studies.   Cost scaling factors based  on gas and product
 rates  are used to calculate values at conditions other than  the base
 case.


       TABLE 5.   DESIGN  CONDITIONS FOR ABSORBER SYSTEM CALCULATIONS
          Operating conditions
Generic lime
 spray dryer
Limestone
Presaturator
Type
Liquid 3
Liquid/gas, gal/kaft
Pressure drop, in. H20
Absorber
Type
Slurry solids, % „
Liquid/gas, gal/kaft
Pressure drop, in. 1^0
Liquid in exit gas, %
Slurry added, % solids
Effluent, % solids
Total pressure drop, in. 1^0

None




Spray dryer
22.5
0.3
2
0.0
22.5
100
12

Venturi
Scrubber
20
9



liquid



Spray tower
15
40
2
0.1
60
15
16








Reheat

     Flue gas reheat to 175 F for both processes is provided by bypassing
part of the incoming flue gas around the absorbers.

Raw Materials

     The raw materials used for each process are listed below.  Limestone
is crushed and wet ground as part of the scrubbing operation.  The lime
is not processed before use.
                                   10

-------
                                                   Generic  lime  spray
           Property	Limestone process        dryer  process
Size as received
Ground size
Analysis „
Bulk density, Ib/ft
0 - 1-3/4 in.
10% to pass 200 mesh
90% CaC03
95
3/4
90%
55
- 1-1/4 in.
CaO
Waste Disposal

     The disposal area is located one mile from the plant site.  An
earthen-diked, clay-lined pond, designed to minimize the sum of land and
construction costs, is used for the limestone slurry process.  Pond
evaporation is assumed equal to rainfall.  The limestone process waste
is assumed to settle to a 40% solids sludge.  An area-fill type landfill
is used for the generic lime spray dryer process.  The landfill size is
based on a waste bulk density of 50 Ib/ft-* and a 30-ft fill depth.

     Provisions for normal site maintenance of the pond and for normal
landfill operations, including covering the waste and contouring to
control runoff are included.  No costs are provided for monitoring or
post-operation maintenance.
ECONOMIC PREMISES

     The economic premises are divided into capital costs for construction
of the FGD system and annual revenue requirements for its operation.
The premises are based on regulated utility economics using the design
premises as a costing basis.  The estimates use cost information obtained
from engineering-contracting, processing, and equipment companies; raw
material suppliers; and published cost indexes.  Spray dryer costs were
obtained by scaling vendor-supplied information.  Raw material costs are
based on those prevailing in the Upper Great Plains - Rocky Mountain
region.  Labor costs are assumed equivalent to those in the Midwest.

Capital Costs

     The capital structure for the electric utility company is assumed
to be:

                            Common stock     35%
                            Preferred stock  15%
                            Long-term debt   50%
                                    11

-------
 The  cost  of  capital  is  assumed  to  be:

                      Common stock                11.4%
                      Preferred  stock            10,0%
                      Long-terra  debt               9.0%
                      Weighted cost of  capital
                       (based on capital  costs
                      above)                     10.0%

 The  discount rate  is 10%,  the same as  the weighted  cost  of  capital.

      For  other  economic factors needed in financial calculations, the
 following values are assumed:

                     Investment  tax credit            10%
                     Federal and State  income tax     50%
                     Property tax and insurance      2.5%
                     Annual  inflation rate            6%

 The  levelized annual capital charge  approach used in these  premises is
 similar to that used by the Electric Power Research Institute  (EPRI) (3).

 Depreciation—
      A 30-yr economic life  and  a 30-yr tax life are assumed for the
 utility plant.  Salvage value is less  than 10% and  is equal to removal
 costs.  The  annual sinking  fund factor for a 30-yr  economic life and
 10.0% weighted cost  of  capital  is:

               Sinking  fund factor = Q + wcc)n - f = °-61%             (1)


       where:  n = economic life (in years)
               WCC = weighted cost of  capital (as a decimal fraction)


 The  use of the sinking  fund factor does not indicate that regulated
 utilities commonly use  sinking  fund  depreciation.   The sinking fund
 factor is used since it  is  equivalent  to straight-line depreciation
 levelized for the economic  life  of the facility using the weighted cost
 of capital.

      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 (4).  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.

                                   12

-------
     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:
             Accelerated tax depreciation = - -, - + \\ (WCC)


     where:  CRF  = Capital recovery factor  (weighted cost of capital
                     plus sinking fund factor) for the economic life
                     (as a decimal fraction)
             CRF  = Capital recovery factor  for the tax life
                     (as a decimal fraction)
               nT = Tax life  (in years)

                                                             TTR
Levelized accelerated depreciation credit =  (ATD  -  SLD) x
                                                             —  1 IK
     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)

For  a  50%  tax  rate,  30-yr  tax life,  30-yr book life, 10.0% weighted cost
of capital,  and 0.61%  sinking fund  factor,  the annual  levelized accelerated
depreciation credit  is 1.36% using  flow-through  accounting.

Investment Tax Credit —
     The levelized investment tax credit  is calculated as follows :
                                     (CRF  ) (Investment tax  credit rate)
  Levelized investment tax credit =
                                             n  + wee1)  f  - TTRl -

   where CRF ,  WCC,  and ITR are the same factors previously defined in
   equations (1)  and (2).

 Using a 10.0%  weighted cost of capital, 0.61% sinking fund factor, 10%
 investment tax credit rate, 50% income tax rate, the levelized investment
 tax credit is  1.92% annually.

 Income Tax —
      The levelized  income tax is calculated as follows:

     , .   j •      „      r™^   , x-rr, OT^I ri   Debt Ratio x Debt CostT r  ITR  -\
 Levelized income tax = 1CRFB + AIR- SLD ] [1 -- ^j - J 4 _ ITRJ
                                                                          (4)
      where:  AIR = Allowance for interim replacement
                                    13

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 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%.

 Annual Capital Charge—
      The levelized annual  capital charges for a publicly  owned electric
 utility, as shown in Table  6,  are 14.7% of the  total investment.   The
 annual capital charge includes charges for the  capital recovery factor,
 interim replacements,  insurance,  and  property taxes, State and Federal
 income taxes,  and credits  for  investment credits  and accelerated  deprecia-
 tion.
                TABLE  6.   LEVELIZED ANNUAL  CAPITAL  CHARGES

                      FOR  REGULATED UTILITY FINANCING
                                           Capital charge, %

            Capital  recovery  factor               10.61
            Interim  replacements                  0.56
            Insurance and property taxes          2.50
            Levelized income  tax                  4.31
            Investment credit                     (1.92)
            Accelerated depreciation              (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 cumulative
effect of these factors makes an insignificant  change in the annual
capital charge rate and is therefore ignored.

Capital Investment Estimates

     Capital investment estimates for this study are based on an Upper
Great Plains and Rocky Mountain location and represent projects beginning
in 1981 and ending in 1983.  Capital cash flows for a standard project
are assumed to be 25% the first year, 50% the second year, and 25% the
third year of the project life.  Capital costs  for fixed assets are
projected to mid-1982, which represents the approximate midpoint of the
                                    14

-------
construction expenditure schedule.   The estimates in this study are
based on a process description, flowsheet, material balance, and equipment
list.  These preliminary-level estimates are considered to have a -20%
to +40% range of accuracy.

     The total fixed capital investment consists of direct capital costs
for equipment, building, utilities, service facilities, raw material and
byproduct storage, waste disposal facilities, engineering design and
supervision, construction expense, contractor fees, and contingency.
The total capital investment consists of the total fixed capital invest-
ment plus allowances for startup and modifications, royalties, the cost
of funds during construction, plus the cost of land and working capital.

Direct Capital Investment Process—
     Direct capital costs cover process equipment, piping,  insulation,
transport lines,  foundations, structures, electrical equipment, instru-
mentation, raw material and byproduct storage, site preparation and
excavation, buildings, roads and railroads, trucks, and earthmoving
equipment.  Direct investment costs are prepared using the  average
annual Chemical Engineering  (5) cost indexes and projections as shown  in
Table 7.
                  TABLE 7.  COST INDEXES AND PROJECTIONS

Year
Plant
Material
Labor
1978
218.8
240.6
185.9
1979a
240.2
262.5
209.7
1980
259.
286.
226.
a
4
1
5
1981
278.
309.
244.
a
9
0
6
1982a
299.8
333.7
264.2
1983
322.
360.
285.
a
3
4
3
1984
344.
385.
305.
a
9
6
3

a. TVA projections.
b. Same as index in Chemical Engineering
(5) for
"Equip
imei
it,

      c.
machinery, supports."
Same as index in Chemical Engineering (5) 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
 in the  process capital costs.

 Direct  Capital Investment - Utilities,  Services and Miscellaneous—
      Necessary electrical substations and conduit and steam, process
 water,  fire and service water, instrument air, chilled water, inert gas,
 and compressed air distribution facilities are included in the utilities
 investment.  These facilities are costed as increments to the facilities
 already required by the power plant.   Service facilities such as maintenance
                                     15

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 shops,  stores,  communications,  security,  offices, and road and railroad
 facilities are  estimated  on  the basis  of  process  requirements.  Services,
 non-power  plant 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  6%  rate is used  in this evaluation for both processes.

 Indirect Capital Investment—
      Indirect capital investment covers engineering design and supervision,
 architect  and engineering contractor costs, construction costs, contractor
 fees, and  contingency.  Construction facilities  (which include costs for
 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 construc-
 tion  expenses and  are charged to indirect capital investment.

      Listed  below  are the indirect  costs  used:

                                                % of direct investment

      Engineering design and  supervision                   7
     Architect  and engineering  contractor                 2
     Construction  expense                                16
     Contractor fees                                       5

           Total                                           30

A  contingency of 20%  is included because  projects normally have a higher
likelihood of exceeding rather  than underrunning  the capital estimate.
While actual  projects could  properly have both project and process con-
tingencies of varying amounts,  depending  on the type and developmental
maturity of  the  process,  comparability  among processes could be skewed
by  the use of different contingencies  in  the same study.

Other Capital Charges—
     Startup  and modification allowances  are estimated at 8% to 12% of
the total  fixed  investment depending upon the complexities of the process
being studied.   For these processes a midpoint value of 10% of the total
fixed investment was assumed.

     Cost of  funds during construction  is 15.6% of the total fixed
investment for each process.   This factor is equivalent to the 10%
weighted cost of capital with 25% of the construction expenditures of
the first 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.
                                   16

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     For both processes, royalty fees of 0.5% of the direct investment
are charged.   Land cost is assumed to be $5,000 per acre.

     Working capital is the total amount of money invested in raw materials,
supplies, finished and semifinished products, accounts receivable, and
monies on deposit for payment of operating expenses such as salaries,
wages, raw materials, purchases, taxes, and accounts payable.  For these
premises, working capital is defined as the equivalent cost of 1 month's
raw material, 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 to cover spare parts, accounts
receivable, and monies on deposit to pay taxes and accounts payable.

Annual Revenue Requirements

     Annual revenue requirements use 1984 costs and are based on 5,500
hours of operation per year at full load.  Annual revenue requirements
are divided into direct costs and indirect costs.  Both first-year and
levelized annual revenue requirements are determined.  Levelized annual
revenue requirements are based on a 10% discount factor and a 6% inflation
rate over the 30-yr life of the power unit.  Direct costs consist of raw
materials, labor, utilities, maintenance, and analytical costs.  Indirect
costs consist of levelized annual capital charges and overheads.

Direct Costs—
     Projected raw material, labor, and utility costs are listed in
Table 8.  Unit costs for steam and 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 net  power output of  the
boiler excluding the electricity consumed by the pollution control
systems.  Actually, electrical use by  the pollution control  equipment
after the ESP will result  in a derating of  the utility plant  for  either
a new or a retrofitted  unit.  To minimize iterative calculations, the
pollution control equipment  is charged with  purchased electricity instead
of derating the utility plant.

     Maintenance costs  are estimated as a percentage  of the  direct
investment, based on unit  size and process  complexity.  For  the  limestone
slurry process, non-pond maintenance is 8%  and  pond maintenance  is  3%.
For  the  generic lime spray dryer  process, maintenance is  6%.

Indirect Costs—
      The levelized annual  capital  charges consist  of  a sinking  fund
factor,  an allowance for interim  replacement,  property  taxes,  insurance,
weighted cost of capital,  income  tax,  credits  for  accelerated  depreciation,
and  investment  credit.   The  levelized  annual capital  charge  for  a regulated
utility, as was shown  in Table  6,  is  14.7%.
                                    17

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                TABLE  8.   PROJECTED  1984 UNIT COSTS FOR RAW

                      MATERIALS, LABOR, AND UTILITIES
                                             $/unit
               Raw materials
                 Limestone
                 Lime
               Labor
                 Operating labor
                 Analyses
                 Mobile equipment
               Utilities
                              Q
                 Process water
                 Electricity
8.50/ton
102.00/ton

15.00/man-hr
21.00/man-hr
21.00/man-hr

0.14/kgal
0.037/kWh
               a.  Varies according to process-dependent
                   water requirements.
     Plant and administrative overhead is 60% of conversion costs less
utilities.  The plant and administrative overheads include plant services
such as safety, cafeteria, medical, plant protection, janitor, purchasing
personnel, general engineering (excluding maintenance), interplant
communications and transportation, recreational facilities, and the
expenses connected with management activities.  Fringe benefits such as
retirement, vacation, dental and medical plans are included in the base
wage rates.
                                   18

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                    PROCESS BACKGROUND AND DESCRIPTION
GENERIC LIME SPRAY DRYER PROCESS

     The generic lime spray dryer process (Figure I and Table 9) is a
relatively simple processing system requiring few items of process
equipment.  Makeup lime is slurried, atomized into the flue gas stream,
and the resulting waste material is collected along with the fly ash in
the baghouse.  The concentration of the lime slurry is adjusted so that
the amount of water injected into the flue gas stream does not saturate
the flue gas.  Mist eliminators (a frequent source of operating problems)
are not required.  In addition, since the flue gas stream is unsaturated,
the waste material is collected as dry particulate matter.

     In this particular application (primarily due to both the relatively
low S02 removal required and the highly alkaline nature of the fly ash),
most of the collected waste material is reslurried and recycled through
the spray dryer.  This recycling of waste material increases the lime
utilization in the process and thereby reduces the consumption of this
costly alkali raw material.  The waste that is not recycled  is  trucked
to a landfill for disposal.

     Flue gas bypass around the spray dryer is used in this  application
because it is more economical to treat part of the flue gas  at  a higher
S02 removal efficiency than to remove 70% of  the S02  from all of the
flue gas.  By using flue gas bypass and having hot (-300 F)  flue gas
available for reheat, the spray dryer can be  operated so that the
treated flue gas more closely approaches the  flue  gas saturation temper-
ature.  As the flue gas approaches  saturation temperature, the  alkali
droplets  retain  their moisture longer and increase the liquid-phase
residence time for S02 absorption.  This results in a better raw material
utilization  (as  well as a higher S02 removal  efficiency) in  the spray
dryer.  Although there is an additional  capital  investment for  the flue
gas bypass ductwork, this is offset by both the  lower capital investment
for the spray dryers and  the lower  annual cost for lime.

Process Description

      Flue gas  from the boiler  air heater enters  the  three  operating
 trains (the  fourth is  a  spare)  of  the FGD system through  a common  plenum.
Most  of  the  flue gas  (78%)  from the plenum  passes  directly into the  top
 of the spray dryers. The  rest  of  the  flue gas bypasses  the spray  dryers
 for reheat  purposes.   The spray dryer  contains  an  atomizing system
                                    19

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N3
o
      Figure 1.  Generic lime spray dryer process.  Flow diagram.

-------
           TABLE 9.   GENERIC LIME SPRAY DRYER PROCESS




                         MATERIAL BALANCE



1
2
t
.',
',
((
/
fi
")
1°
Stream No.


Total stream. Ib/hr
sft^min at 60°F
Temperature, °F
Pressure, psisi
Rpm
Specific gravity
pH
Undisaolved solids. Z


1


489,700









2
Combustion air

5,119,000
1,131,066
80







3
Combustion air

4,419,000
976,466
535







4
Gas to
econom zer
4,897,000
1,045,000
890







5
Gas to
air neater
4,897,000
1,045,000
705







Stream No,
Description
1

1
'.
'}

/
8
9
10
Total stream, Ib/hr
sft3/min at 6Qf>F
Temperature, °F
Pressure , psig
gpm
Specific gravity
PH
Undissolved solids, %


11
Waste to
recycle
parttculate silo
55,450









12
Makeup water
to recycle
slurry tank
83,150



166





13
Recycle slurry
to spray dryer
138,600






iO


14
Makeup lime
to slaker
3,661









15
Makeup water
to slaker
11,350



23





Stream No.

1

i

'}
it
/
H
4
10
Description
iQtal sueam. Ib/hr
sftVmtn at 6Q°F
Temperature, °F
Pressure , psig
Kpm
Spt'cific gravity
PH
Undissolved solids, %


16
Grit to
landfill
366









17
Lime slurry to
spray dryer
14,650






22.5


18
Dilution water
to spray drver
19,890

60

40





























a.  Includcs air inleukage Into the
                                     21

-------
designed to spray the lime slurry and a waste recycle slurry perpen-
dicularly to the gas flow in the spray dryer.   (The lime slurry and the
waste recycle slurry are combined into a single stream and atomized in
the spray dryer.)  The SOX and HC1 in the  flue gas react readily with
the lime slurry by the following reactions:

                       Ca(OH)2 + S02 -> CaS03 4- H20f                     (5)


                       Ca(OH)2 + SCL -> CaSO^ + H20t                     (6)

                      Ca(OH)  + 2HC1 -> CaCl  + 2HOt                    (7)
In addition to these primary reactions, the following secondary reaction
also occurs:
                           CaS03 + 1/202 -*• CaS04                        (8)
The water content of the feedstreams is controlled so that all of the
water fed to the spray dryer evaporates and the mixed calcium salts and
fly ash leave the spray dryer as dry particulate matter entrained in the
flue gas.  Since the flue gas is not saturated and contains no liquid
carryover, mist eliminators are not required.  The particulate matter-
laden flue gas from thp. bottom of the spray dryer is mixed with the
300°F flue gas which bypassed the spray dryer and is passed to the
baghouse.  The baghouse not only removes the fly ash and the calcium-
based particulate matter from the flue gas, but it also significantly
increases the contact time between the calcium-based particulate matter
and the SC>2-containing flue gas.  This increased contact time leads to
the additional conversion of both SOX by reactions (5) and (6) and
CaSO-j by reaction (3) .  The flue gas from the baghouse passes through an
ID fan and is vented to the stack.  The flue gas enters the stack at
about 175 F and, therefore, additional reheat is not required.

     The fabric bags in the baghouse are cleaned periodically.  The
particulate matter drops into hoppers at the bottom of the baghouse.
Pneumatic conveyors move the particulate matter to either the recycle
storage silos or the waste storage bins.  Waste solids from the silo are
reslurried with makeup water and recycled through the spray dryer.  The
waste storage bin is emptied into trucks for transport to a landfill.

     Bulk shipments of pebble lime are received by rail and sent to the
storage silo.  The lime is periodically moved to intermediate storage
bins from which process requirements are removed.  The pebble lime from
the bins is slaked with makeup water and pumped as a 22.5% slurry to the
lime slurry tank.  This makeup slurry is pumped to the spray dryer as
needed.
                                    22

-------
Analysis of Processing Subsections

     To facilitate cost determinations and comparisons, the lime process
is divided into seven processing sections and the processing equipment
is assigned to the appropriate section.  The equipment list, giving the
description and cost of each equipment item by section, is shown in
Table 10.  These costs do not include the investment required for founda-
tions, structures, electrical components, piping, instruments and controls,
etc.  Each of these processing sections is described in more detail
below.

Material Handling—
     This and the following section, feed preparation, compose the raw
material receiving and preparation section.  The material handling
section includes all of the equipment to receive lime by rail and to
maintain a supply of lime to the weigh feeders.  It includes a lime
storage silo with a 30-day capacity and two lime feed bins each having a
12-hr capacity.

Feed Preparation—
     The feed preparation sections include the equipment necessary to
convert the makeup lime into slurry for S02 absorption.  Two trains of
lime preparation equipment (feeders, slakers, tanks, and agitators) are
used.  Each train is sized to handle 50% of the full load capacity.  A
slurry feed tank with a 4-hr capacity is provided.

Gas Handling—
     Included in this area is an inlet plenum interconnecting the flue
gas ducts which feed the scrubber trains.  It also includes the bypass
ducting around the spray dryers.  Four ID fans are provided between the
baghouse and the stack to compensate for the pressure drop through the
FGD system.

S02 Absorption—
     Four spray dryers are provided (three operating and one spare);
each is sized to handle one-third of the total flue gas volume.

Particulate Removal—
     A single baghouse containing 28 compartments and the associated
equipment is provided.

Particulate Handling and Recycle—
     A single train of equipment to store, reslurry, and recycle the
waste material is provided.  Two particulate storage bins are included
to provide a 24-hr capacity for waste material to be landfilled.

Waste Disposal—
     This section contains no processing equipment.  It includes trucks
to transport the waste absorbent to the landfill and earthmoving equipment
                                    23

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                 TABLE  10.  GENERIC LIME  SPRAY DRYER PROCESS

                BASE-CASE  EQUIPMENT LIST,  DESCRIPTION, AND COST

Area

1 — Material Handling
Item No. Description

Total
material
cost,
1982 $

Total
labor
cost,
1982 $
 1.  Conveyor, lime           1
    unloading (enclosed)
2.  Elevator, storage       1
    silo
3.  Silo, lime
    storage
    Vibrators

4.  Conveyor, live
    lime feed
5.  Elevator, live
    lime feed
6.  Bin, lime feed
Belt, 24 in. x  1,500 ft    390,000   242,800
long, 30 hp, 100 tons/hr,
200 ft/min

Continuous bucket, 16 in.   33,600     3,300
x 8 in. x 11-3/4 in., 75
ft lift, 15 hp, 100 tons/hr,
160 ft/min

40 ft dia x 50  ft straight  65,200   194,300
side, 62,800 ft3, 60°
slope, carbon steel

Bin activator,  10 ft dia    14,000     1,300

Belt, 14 in. x  100 ft       23,800     7,600
long, 2 hp, 16  tons/hr,
100 ft/min

Continuous bucket, 8 in.    49,300     4,000
x 5-1/2 in. x 7-3/4 in.,
35 ft lift, 2 hp, 16 tons/
hr, 150 ft/min

11 ft dia x 12  ft straight  10,600    28,200
side, 1,140 ft3> 60° slope,
w/cover, carbon steel
7.  Dust collecting
    system
    Subtotal
Bag filter, polypropylene
bag, 2,200 ft3/min, 7-1/2
hp (1/2 cost in feed prepa-
ration area)
3,900
600
                           590,400   482,100
                                  (continued)

                                      24

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                            TABLE 10  (continued)

Area 2 — Feed Preparation


1.
2.
3.
4.

Item
Feeder, lime
bin discharge
Feeder, slaker
Slaker
Tank, slaker

No. Description
2 Vibrating, 3-1/2 hp, carbon
steel
2 Screw, 12 in. dia x 12 ft long,
1 hp, 2 tons/hr
2 5 hp slaker, 1 hp classifier,
1.0 ton/hr
2 6 ft dia x 8 ft high, 1,700
Total
material
cost,
1982 $
8,400
6,600
72,500
5,400
Total
labor
cost,
1982 $
800
400
23,900
7,500
    product
gal, open top, four 6 in.
baffles, agitator supports,
carbon steel, neoprene lined
5.  Agitator, slaker
    product tank

6.  Pump, slaker
    product tank
 7.  Tank, slurry
    feed
2 turbines, 24 in. dia,
3 hp, neoprene coated

Centrifugal, 40 gpm, 50 ft
head, 1-1/2 hp, carbon steel,
neoprene lined
(2 operating, 1 spare)

10 ft dia x 12 ft high, 7,100
gal, open top, four 10 in.
baffles, agitator supports,
carbon steel, neoprene lined
15,800     1,800


 5,300     2,300




 6,500     9,500
 8.   Agitator,  slurry
     feed  tank

 9.   Pump,  slurry
     feed  tank
10.   Dust collecting
     system


     Subtotal
40 in. dia, 7-1/2 hp, neoprene
coated

Centrifugal, 40 gpm, 200  ft
head, 5 hp, carbon  steel,
neoprene  lined
 (3 operating, 5 spare)

Bag  filter, polypropylene bag,
2,200 ft3/min, 7-1/2 hp,  (1/2
cost in material handling area)
15,300


40,000
 3,900
1,300


6,000
  600
                                  179,700    54,100
                                   (continued)

                                       25

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                             TABLE 10  (continued)
 Area  3—-Gas  Handling
         Item
         No.
    Description
  Total
material
  cost,
  1982 $
 1.  Fan
              Induced  draft,  382,000
              aft3/min,  12  in.  static
              head,  875  rpm,  1,250 hp,
              fluid  drive,  double width,
              double inlet  (4 operating)
    Subtotal
                      3 rotary atomizers, carbon
                      steel, (3 operating, 1 spare)
    Subtotal
Total
labor
cost,
1982 $
                           1,583.600     99.600
                                            1.583.600     99,600
Area 4 — S0? Absorption
Item No. Description
1. Spray dryer 4 48 ft dia x 54 ft high, with
Total
material
cost,
1982 $
4,324,000
Total
labor
cost,
1982 $
548.000
                                           4,324.000    548,000
Area 5—Particulate Removal
    Item
No.
Description
 Total      Total
material    labor
 cost,      cost,
 1982 $     1982 $
1.   Baghouse   1
    Subtotal
     Automatic fabric filter, 28 compart-  8,262,000^  2,871.100
     ments, 2.5 air-to-cloth ratio

    	8.262.000  2.871.100
                                   (continued)

                                      26

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                           TABLE 10  (continued)
Area 6 — Particulate Handling
Item No.
and Recycle
Description

Total
material
cost,
1982 $

Total
labor
cost,
1982 $
1.  Conveyor,  particu-  1    Pneumatic,  pressure-vacuum,
    late feed  to bin        250 hp
2.  Bin, particulate
    storage
                    2   24 ft dia x 25  ft straight
                        side, 11,300 ft3, 60° slope,
                        w/cover,  carbon steel
                                                        243,100
                                            75,600
                                 43,600    131,400
3.
Vibrator            2

Silo, particulate   2
recycle
Bin activator, 10 ft dia

25 ft dia x 30 ft straight
side, 14,700 ft3f 60° slope,
w/cover, carbon steel
18,600      2,500

51,200    149,700
4.  Feeder, particu-
    late

5.  Feeder, recycle
    slurry tank

6.  Tank, recycle
    slurry
                        Vibrating, 3-1/2 hp, carbon
                        steel

                        Screw, 12 in. dia x 12 ft
                        long, 5 hp, 50 tons/hr

                        21 ft dia x 23 ft high,
                        55,400 gal, open top, four
                        21 in. baffles, agitator
                        supports, carbon steel, neo-
                        prene lined
                                  8,400        800


                                 30,800      4,500


                                 25,700      38,700
 7.  Agitator, recycle
    slurry  tank

 8.  Pump, recycle
    slurry  feed
     Subtotal
                        84 in. dia, 30 hp, neoprene
                        coated

                        Centrifugal, 80 gpm, 200 ft
                        head, 10 hp, carbon steel,
                        neoprene lined
                        (3 operating, 5 spare)
                                  42,100
                                  65.400
             2,600
             7,600
                                                         528.900     413.400
 Basis:   Most  equipment  cost estimates are based  on  informal  vendor  quotes  and
         TVA information.  The only  exception  is  the cost  for the spray dryers
         which is  based  on information supplied by the vendor.

         These costs  represent equipment  costs only.   Costs  for piping, elec-
         trical equipment, instruments, foundations,  and other installation
         costs are not  included.   The differences in area  costs between the
         equipment list  and  the  capital summary sheets are due to these installa-
         tion  costs.                   27

-------
to distribute the waste evenly throughout the landfill.  Therefore,
these costs are not  shown  in  the equipment list, but rather they are
listed as a direct investment component of the capital investment.


LIMESTONE SLURRY PROCESS

     The limestone slurry  process  (Figure 2 and Table 11) is also a
relatively simple processing  system requiring few items of process
equipment.  Although not usually considered as part of the FGD system, a
high-efficiency  (99.8%) ESP has been  included in the limestone slurry
process upstream of  the FGD system.   This change in the typical economic
analysis of the limestone  slurry process  (i.e., including the cost of
the ESP's) is necessary to provide comparability with the generic lime
spray dryer process.

     Another significant design change for the limestone slurry process
is the inclusion of  partial flue gas  bypass around the scrubber.  Since
only 70% SC>2 removal is required in this low-sulfur coal application, it
was considered more  economical to design the FGD system for 90% S02
removal and treat only enough flue gas to meet the required S02 reduction.
Under these conditions sufficient heat is available from the bypassed
gas to eliminate the need  for additional reheat.

     Otherwise the limestone  slurry process is of conventional design.
The makeup limestone is ground, slurried, and added as needed to maintain
a 15% solids slurry  recirculating through the scrubber.  A purge stream
is bled off the absorber loop and is  pumped to the disposal pond.  The
pond supernate is recycled and reused in the process.  The fly ash from
the ESP is trucked to and  disposed of in the pond.

Process Description

     The flue gas from the boiler air heater passes through both the
high-efficiency ESP  and the power plant ID fans before entering a common
plenum.  This common plenum distributes the gas to four trains of FD
booster fans and absorbers.   (Three of these scrubber trains are operating
and one is a spare.)  These FD booster fans are provided downstream of
the plenum to compensate for  the pressure drop in the FGD system.

     Approximately 28% of  the 300°F flue gas from the booster fan bypasses
the venturi/spray tower absorbers and enters the ducts downstream from
the absorbers for reheat purposes.  The remaining flue gas enters a
venturi absorber where the flue gas,  in contact with recirculated limestone
slurry, is adiabatically cooled and saturated.  This cooled flue gas
enters the spray tower absorbers and  passes countercurrently to the
recirculating 15% solids limestone slurry which absorbs the SOX.  The
absorbers are equipped with chevron-type mist eliminators.  Absorber
outlet gas is heated from  130°F to 175 F before entering the stack by
mixing with the bypassed flue gas.
                                    28

-------
                         BOILER
to
VO
                                 ,"     ELECTROSTATIC

                             'ECONOMIZER!   PRECIPITATOR
                                                    FD
                                                    FAN
            COAL
                                                                                                                POND SUPERNATE
                                                                                                                   RETURN
                                                                                                                 TO WASTE

                                                                                                               DISPOSAL POND
           Figure 2.   Limestone  slurry process.   Flow diagram.

-------
TABLE 11.  LIMESTONE SLURRY PROCESS




         MATERIAL BALANCE

Description
I
I
\
'.

6
7
H
9
|0
Total stream, Ib/hr
«fr3/mln at 60<>F
Temperature. °F
pressure. osiff

Soecific Rravltv
oH
Undissolved solids, 7.


1
Coal to boiler
489,700









2
Combustion air
to air heater
5, 119,000
1,131,000
80







3
Combustion air
to boiler
4 ^4 11,000
976,400
535







4
Gas to
economizer
4,897,000
1,045,000
896







5
Gas Co
air heater
4,897,000
1.045.000
7S5










L
k
')
ft
/
H
9
Iff


Description
/rain at 60OF
Pressure, psift
pom
Specific ftravity
uH
Undissolved solids, X


6

Gas to ESP
] ,700.000







7


863.200







8
Gas from

922.300







9

Gas to stack
1.259.000







10

to venturi


20.930


15




1
;
i
4
'>
;
H
9
10
§tream No.
Description
Total stream, Ib/hr
sft'/min at 60OF
Temperature, QV
Pressure, psla

uH
Undisaolved solids. £


11
Makeup water
to scrubber
170,100



340




12
Reclrculated
slurry to
absorber
23,050,000

130

41.860

15


13
Slurry to pond
48,810



89

15


14
Pond supernace
to reclrcutatlon
tank
26,690



53




15
limestone to
weigh belts
5,728










|


s
fl
/
8
4
IU
J t ream No.
Description
Total stream, Ib/hr
sftVnln at 60op
prflflfl.Mrp- psig

sB6Cific gravity
oH
Unrflosnlved solids. %


16
Pond supernate
to wee
ball mill
3,820


8





17
Mills product
tank feed
9,546


12


60


18
Makeup slurry
to recirculat ion
tank
9,546


12


60
























                 30

-------
     A bleedstream from the  recirculation  tank is  fed to  the pond feed
tank from which it is pumped to the onsite pond.   The solids in the
slurry settle to form a sludge containing  approximately 40% solids.  The
pond supernate is recycled to the wet ball mills  and the  absorber recir-
culation tank.

     Makeup limestone is received by rail  and stored in a pile onsite.
The limestone is removed from the pile and fed first to gyratory crushers
and then to ball mills where it is wet ground to  70% minus 200 mesh.
The effluent from the ball mill is stored  as a 60% solids slurry, first
in the ball mill product tank and then in  the slurry feed tank.  This
makeup limestone slurry is pumped to the absorber recirculation tank
where it is combined with scrubber effluent slurry and recycle pond
water to maintain a 15% solids content in the recirculating slurry.

Analysis of Processing Subsections

     To facilitate cost determinations and comparisons, the limestone
slurry process is divided into six processing sections and  the processing
equipment is  assigned to the appropriate section.  The equipment list,
giving the description and cost of each equipment item by  section,  is
shown in Table 12.  These costs do not include the  investment  required
for  foundations,  structures, electrical components,  piping,  instruments,
and  controls,  etc.  Each of  these processing  sections  is described
below.

Material Handling—
      This area includes all  of the  facilities needed for receiving the
raw  limestone,  areas  for a  storage  stockpile  sufficient  for 30 days at
normal operating conditions,  and  an in-process limestone storage for 24
hours.

Feed Preparation—
      A single train  of gyratory crushers  and  wet  ball  mills to convert
the  raw  limestone to a 70%  minus  200 mesh,  60% solids  slurry is included
in this  area.  It also contains a product storage tank with capacity
equal to an 8-hr supply of  makeup slurry.

Particulate Removal—
      Four high-efficiency ESP units (99.8% removal)  are  included in this
area.  These ESP's  are sized for a low-sulfur, western coal application.

 Gas  Handling—
      Included in this area is one inlet flue gas plenum interconnecting
 the four flue gas ducts which feed the absorbers and four FD fans.  Also
 included are the FD fans and the bypass ducting  around the absorbers.
 Each of these FD fans is sized to handle  one-third of the  total flue gas
 volume and to compensate for the pressure drop in the FGD  system.
                                    31

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                      TABLE 12.   LIMESTONE SLURRY PROCESS

                BASE-CASE EQUIPMENT LIST,  DESCRIPTION,  AND COST
Area 1 — Materials Handling



1.
2.

3.

4.


Item
Mobile equipment
Hopper, reclaim

Feeder, live
limestone storage
Pump , tunnel sump


No.
1
1

1

2


Description
Bucket tractor
7 ft x 4-1/4 ft x 2 ft
deep, carbon steel
Vibrating pan, 3.5 hp

Vertical, 60 gpm, 70 ft head,
Total
material
cost,
1982 $
60,800
700

15,400

4,300
Total
labor
cost ,
1982 $
—
1,300

2,700

1,100
5.  Conveyor, live
    limestone feed
6.  Conveyor, live
    limestone feed
    (incline)

7.  Elevator, live
    limestone feed
8.  Bin, crusher        1
    feed

9.  Dust collecting     1
    system
    Subtotal
 5 hp,carbon  steel, neoprene
 lined
 (1 operating,  1 spare)

 Belt, 30  in. wide x  100 ft
 long, 2 hp,  100 tons/hr,
 60 ft/min

 Belt, 30  in. wide x  190
 ft long,  40 hp, 35 ft lift,
 100 tons/hr, 60 ft/min

 Continuous bucket, 12 in. x
 8 in. x 11-3/4 in.,  75 hp,
 90 ft lift, 100 tons/hr,
 160 ft/min

 13 ft dia x 21 ft high, w/
 cover, carbon steel

 Bag filter, polypropylene
bag,  2,200 aft3/min,  7-1/2
hp, automatic shaker system
 34,300
102,800
  6,900


  6,700
 6,300
 48,000    20,300
 2,400




14,500


18,100
                                 279,900    66.700
                                  (continued)


                                     32

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TABLE 12 (continued)
Area


1.
2.
3.
4.
5.
6.
7.
8.
9.
10.


2 — Feed Preparation

Item No.
Feeder , crusher 1
Crusher 1
Ball mill 1
Tank, mills 1
product
Agitator, mills 1
product tank
Pump, mills 2
product tank
Tank, slurry 1
feed
Agitator, slurry 1
feed tank
Pump, slurry 6
feed tank
Dust collecting 1
system
Subtotal



Total
material
cost,
Description 1982 $
Weigh belt, 18 in. wide x 14 23,100
ft long, 2 hp, 3.0 tons/hr
Gyratory, 0 x 1-1/2 to 3/4 in., 67,700
75 hp, 3.0 tons/hr
Wet, open system, 100 hp, 174,400
3.0 tons/hr
10 ft dia x 10 ft high, 5,500 6,200
gal, open top, four 10 in.
baffles, agitator supports,
carbon steel, flakeglass lined
36 in. dia, 10 hp, neoprene 10,500
coated
Centrifugal, 12 gpm, 60 ft 6,200
head, 1 hp, carbon steel,
neoprene lined
(1 operating, 1 spare)
11 ft dia x 11 ft high, 7,500 4,300
gal, open top, four 11 in.
baffles, agitator supports,
carbon steel, flakeglass lined
44 in. dia, 15 hp, neoprene 11,000
coated
Centrifugal, 4 gpm, 60 ft 17,700
head, 1/4 hp, carbon steel,
neoprene lined
(3 operating, 3 spare)
Bag filter, polypropylene 6,700
bag, 2,200 aft3/min, 7-1/2
hp, automatic shaker system
328,200
(continued)
33

Total
labor
cost,
1982 $
1,800
7,600
17,800
11,000
500
1,400
10,500
900
4,300
18,100
73,900



-------
                            TABLE 12 (continued)
Area 3—Particulate Removal
        Item
No.
Description
 Total     Total
material   labor
 cost,     cost,
 1982 $    1982 $
1.  ESP
 4   99.8% removal efficiency
     SCA = 700
2.  Conveyor, flyash   1   Pneumatic, pressure-vacuum,
    to particulate         75 hp
    bin

3.  Bin, particulate   2   25 ft dia x 27 ft high,
                           w/cover, carbon steel
                      8,020,000  4,010,000
                                     109,800     69,300
                                      39,000    108,600
4.  Vibrator

    Subtotal
 2   Bin activator,  10 ft dia
                         28,000       2,600
Area 4 — Gas Handling
Item No. Description
1. Fans 4 Forced draft, 421,000
Total
material
cost,
1982 $
2,276,200
Total
labor
cost,
1982 $
147,500
                           890 rpm,  2,250  hp,  fluid
                           drive,  double width,  double
                           inlet
                           (3  operating, 1 spare)
    Subtotal
                                   2.276.200   147.500
Area 5 — SO? Absorption



Item No.
1. Venturi absorber 4






Description
L/G = 20, pressure drop = 9 in.
H20 (3 operating, 1 spare)
(continued)
34
Total
material
cost,
1982 $
632,900



Total
cost,
labor
1982 $
86,000




-------
                            TABLE 12  (continued)
Area 5 (continued)
       Item
                      No.
             Description
                                 Total     Total
                                material   labor
                                 cost,     cost,
                                 1982 $    1982 $
2.  Tank, venturi
    hold
3.  Agitator,
    venturi hold
    tank

4.  Pumps, venturi
    recycle
 5.   S02  absorber
 6.   Tank,  recircula-
     tion
 7.  Agitator, recir-
     culation tank
 8.  Pump, slurry
     recirculation
12
15-1/2 ft dia x 31-1/2 ft
high, 44,500 gal, open top,
four 15-1/2 in. wide baffles,
agitator supports, carbon
steel, flakeglass lined
(3 operating, 1 spare)

62 in. dia, 40 hp, neoprene
coated
(3 operating, 1 spare)

Centrifugal, 7,000 gpm,  100
ft head, 350 hp,  carbon  steel,
neoprene lined
(3 operating, 5  spare)

Spray  tower, 34  ft long  x  17
ft wide x  40 ft high,  1/4  in.
carbon steel, neoprene lining;
FRP  spray  headers, 316 stain-
less steel chevron vane  entrain-
ment separator  and nozzles
 (3 operating,  1  spare)

31-1/2 ft  dia  x 31-1/2 ft  high,
 184,200  gal, open top, four
31-1/2 in. wide baffles, agi-
tator supports,  carbon steel,
 flakeglass lined
 (3  operating,  1 spare)

 124 in.  dia,  60 hp,  neoprene
 coated
 (3 operating,  1 spare)

 Centrifugal,  7,000 gpm,  100
 ft head, 350 hp, carbon steel,
 neoprene lined
 (6 operating,  6 spare)
                                       63,700  156,300
                                       96,900   32,700
                                      421,000   37,000
                                    3,485,000  401,200
                                       158,400   354,500
                                       293,300   99,100
631,500   55,600
                                  (continued)

                                      35

-------
                             TABLE 12  (continued)

Area 5 (continued)


9.

10.

Item No .
Pump , makeup 2
water

Soot blowers 44
Subtotal

Description
Centrifugal, 2,620 gpm, 200
ft head, 250 hp, carbon
steel
(1 operating, 1 spare)
Air, retractable
Total
material
cost,
1982 $
25,600

377,100
6,185,400
Area 6 — Solids Disposal


1.
2.
3.
4.


Item No.
Tank, pond 1
feed
Agitator, pond 1
feed tank
Pumps , pond feed 4
Pumps , pond 2
return
Subtotal

Description
15-1/2 ft dia x 31-1/2 ft high
44,500 gal, open top, agitator
supports, four 15-1/2 in.
baffles, carbon steel, flake-
glass lined
2 turbines, 52 in. dia, 40 hp,
neoprene coated
Centrifugal, 89 gpm, 130 ft
head, 3 hp, carbon steel,
neoprene lined
(2 operating, 2 spare)
Centrifugal, 127 gpm, 200 ft
head, 10 hp , carbon steel,
neoprene lined
(1 operating, 1 spare)

Total
material
cost,
1982 $
15,900
21,700
18,200
6,200

62,000
Total
labor
cost,
1982 $
2,700

318,700
1,543,800

Total
labor
cost,
1982 $
39,100
1,800
3,900
700

45,500
Basis:  Most equipment cost estimates are based on informal vendor quotes and
        TVA information.

        These costs represent equipment costs only.   Costs for piping, elec-
        trical equipment, instruments, foundations,  and other installation
        costs are not included.   The differences in  area costs between the
        equipment list and the capital summary sheets are due to these
        installation costs.
                                      36

-------
SiOo Absorption—
     Four trains (three operating, one spare) of venturi/spray tower
absorbers with mist eliminators, recirculation tanks, and recirculating
pumps are included.  Each absorber train is sized to handle one-third of
the total flue gas volume.

Solids Disposal—
     Included are one pond feed tank with agitator, pond feed and pond
return pumps, and mobile equipment (trucks) to move the fly ash from the
ESP to the sludge pond.
                                    37

-------
                    ECONOMIC EVALUATION AND COMPARISON


     Based on the power plant, process design, economic premises, and
the specific process equipment for each process described in the previous
sections, preliminary capital investment, first-year revenue requirements,
and levelized annual revenue requirements were prepared for the economic
evaluation and comparison of the generic lime spray dryer process and a
conventional limestone slurry process.

     Both first-year and levelized annual revenue requirements are cal-
culated.  First-year annual revenue requirements are useful for comparing
the relative cost differences between processes for their first year of
operation, and they are an indicator of the magnitude of the annual
revenue requirements.  However, these first-year annual revenue require-
ments do not represent the actual cost of operating the plant since they
do not consider either the time-value of money or the inflationary
pressures over the life of the plant.  In order to reflect these costs,
a levelizing factor (1.886) is applied to the first-year annual revenue
requirements to give a levelized annual revenue requirement.  This
levelizing factor is based on a 10% discount factor and a 6% inflation
rate over the 30-yr life of the power unit.

     Sensitivity analyses have also been performed to evaluate the
effects of varying the raw material price and stoichiometry for the
generic lime spray dryer process.   An alternate case involving sludge
fixation for the limestone slurry process has also been included.

     Even though the generic lime spray dryer process, as described and
costed, was assumed to be proven technology, the current status of
development does not fully justify this assumption since none of the
lime spray dryer processes have been operated on a commercial, coal-
fired boiler.  However, for TVA cost estimation purposes each system is
assumed to be proven technology.


ACCURACY OF ESTIMATES

     The accuracy associated with these preliminary cost estimates,
i.e., -20%, +40%, is defined as the relationship between the estimated
costs and what the actual installed costs for the process might be.  The
accuracy assigned to a cost estimate is empirical and not related to
variabilities in a statistical sense, but rather, it depends on both the
amount and the quality of the technical data available.  Accuracy ranges
reflect the numerous uncertainties surrounding estimates made using
simplifying assumptions.  For example, in a preliminary-level estimate


                                  38

-------
in which only a flowsheet,  material  balance,  and  an  equipment  list  are
available—and all other indirect  investments are factored—the uncertainty
surrounding the investment  is much greater  than a definitive-level
estimate where quantities and costs  for  piping, electrical  equipment,
instruments, etc., are calculated  rather than factored.   Therefore  when
estimating the preliminary-level capital investment  for  a particular
process for a particular installation the uncertainty surrounding the
costs would be -20%, +40%.

     However, when comparing the preliminary-level costs for  two competing
process technologies, many of the same simplifying assumptions are made
for each of the processes and therefore the comparability is  much greater
than the accuracy of the estimates.   When directly comparing  two similar
level estimates, the uncertainty ranges associated with the compared
costs are estimated at only llO%.


CAPITAL INVESTMENT

Generic Lime  Spray Dryer Process

     The total capital investment for the generic lime spray dryer
process is  $66.2M  ($132/kW)  in mid-1982 dollars.  This total cost  can be
broken down into  the various  investment cost categories  as shown in
Table 13.   The total direct  investment, which  includes processing  equip-
ment, piping,  etc., accounts  for about  49% of  the total  capital investment.
The  indirect  investments such as engineering design  and  supervision,
architect and engineering  contractor, construction expense, contractor
fees, and project  contingency make  up about  28%  of the  total  capital
investment.   The various other  capital  charges (allowance  for  startup
and  modifications,  interest  during  construction, royalties, land,  and
working capital) make up the remaining  23%.

     The total direct investment  for  the generic lime spray dryer  process
can  be  further subdivided  into  the  various processing areas.   The  major
investment  areas  are  the particulate matter  removal, gas handling, and
S02  absorption areas.   These areas  account for most  (78%)  of  the total
direct  investment.

     Major  indirect investments are project  contingency  at $8.4M and  the
construction expense  at $5.2M.  Engineering  design  and  supervision, con-
tractor fees, and architect  and engineering  contractor  expense contribute
significantly less at $2.3M, $1.6M, and $0.7M respectively.

      Other capital charges,  including allowance  for startup  and modifi-
 cations,  interest during construction,  royalties,  land,  and  working
 capital,  account  for $15.5M of  the  total capital investment.   The allow-
 ance for startup  and modifications  and interest  during construction
 contributed most  to the other capital charges.  Land and royalties were
 relatively insignificant at $0.5M and $0.2M.
                                     39

-------
              TABLE 13.   GENERIC  LIME  SPRAY DRYER PROCESS


                         TOTAL CAPITAL INVESTMENT


         (500-MW  new  coal-fired  power unit,  0.7% S  in coal;
               70% S02  removal; onsite solids disposal)

                                                                Investment, k$

Direct Investment

Material handling                                                   2,443
Feed preparation                                                       599
Gas handling                                                        7,190
S02 absorption                                                      7,173
Particulate removal                                                11,133
Particulate handling  and recycle                                     1,425
Solids disposal                                                        379

     Total  process  capital                                          30,342

Services, utilities,  and miscellaneous                               1,821

      Total  direct  investment excluding  disposal field preparation    32,163

Disposal field preparation                                             321

     Total  direct investment                                        32,484


Indirect Investment

Engineering design  and supervision
Architect and  engineering contractor
Construction expense
Contractor  fees
Contingency

     Total  fixed  investment                                         50,675


Other Capital  Charges

Allowance for  startup and modifications
Interest during construction
Royalties
Land
Working capital

     Total  capital  investment

Dollars of  total  capital per kW of generation capacity
Basis
  Upper Midwest  plant location represents  project beginning mid-1980,  ending
   mid-1983.   Average cost basis for scaling, mid-1982.
  Minimum in-process storage, redundant  scrubber train, and pumps are  spared.
  Disposal area  located one mile from power plant.
  FGD process  investment begins at boiler  air heater exit.  Boiler plenum and
   stack excluded.
  Only nominal construction overtime included.
                                      40

-------
Limestone Slurry Process

     The total capital investment for the base-case application of the
limestone slurry process (a combined particulate-limestone FGD system)
is $93.2M ($186/kW) in mid-1982 dollars,  as shown in Table 14.

     The direct investment for the limestone slurry process can be
further subdivided into the various processing areas.  SC>2 absorption,
particulate matter removal, and gas handling account for nearly 79% of
the total direct investment.  The waste disposal pond construction
represents about 8% of the total direct investment.

     The major indirect investments are project contingency ($11.9M),
construction expense  ($7.3M), contractor fees ($2.3M), and engineering
design and supervision  ($3.2M).  Architect and engineering contractor
costs are significantly less ($0.9M).

     The remaining $22.OM of the total capital investment is  other
capital charges.  The allowance for startup and modifications and interest
during construction together contribute nearly 20% of the total capital
investment and make   up 83% of the other capital charges.  Royalties,
land,  and working  capital are  $0.2M,  $0.9M, and $2.6M respectively.

Comparison

     The total direct investment and  the total capital  investment  for
the  two FGD  systems are shown  in Table 15.  The generic  lime  spray  dryer
process  is substantially  (29%) less  capital intensive than a  limestone
slurry process.

               TABLE 15.   BASE-CASE TOTAL DIRECT INVESTMENTS

                      AND TOTAL  CAPITAL  INVESTMENTS


                                      Total direct   Total capital
                                       investment     investment
Process
Generic lime spray dryer
Limestone slurry
M$
32.5
45.7
$/kW
65.0
91.3
M$
66.3
93.2
$/kW
132.6
186.4

      The major investment differences between the generic lime spray
 dryer process and the limestone slurry process are in the S02 absorption,
 particulate matter removal, solids disposal equipment, and the waste
 disposal area preparation as shown in Table 16.  With the exception of
 the investment for the material handling and feed preparation areas, the
 limestone slurry costs are higher than the costs for the corresponding
 areas in the generic lime spray dryer process.  The lower costs for the
 generic lime spray dryer process in the other areas are due primarily to
 the use of the spray dryer.  The spray dryer technology eliminates the

                                      41

-------
              TABLE  14.   LIMESTONE  SLURRY PROCESS

                    TOTAL  CAPITAL INVESTMENT


     (500-MW new coal-fired power  unit,  0.7%  S in  coal;
           70%  S02 removal; onsite  solids disposal)

                                                        Investment, k$

Direct Investment

Material handling                                             919
Feed preparation                                            1,071
Particulate removal                                        12,395
Gas handling                                                9,924
SO  absorption                                             13,734
Solids disposal                                             1,453

     Total process capital                                  39,496

Services, utilities,  and miscellaneous                       2,370

     Total direct investment excluding pond construction     41,866

Pond construction                                           3,793

     Total direct investment                                45,659


Indirect Investment

Engineering design and supervision                           3,]96
Architect and engineering contractor                           913
Construction expense                                         7,305
Contractor fees                                              2,283
Contingency                                                11,871

     Total fixed investment                                 71,227


Other Capital Charges

Allowance for startup  and modifications                      7,123
Interest during  construction                                11,111
Royalties                                                     228
Land                                                          910
Working capital                                              2,590

     Total capital  investment                               93,189

Dollars of total capital  per kW of generation  capacity       186.38
Basis
  Upper Midwest  plant location represents project beginning mid-1980,
   ending mid-1983.  Average cost basis for  scaling, mid-1982.
  Minimum in-process storage, redundant scrubber train, pumps are spared.
  Disposal pond  located one mile from power  plant.
  FGD process  investment begins at boiler air heater exit.  Boiler
   plenum and  stack excluded.
  Only nominal construction overtime included.
                                  A 2

-------
need for slurry recirculating tanks and pumps and mist eliminators in
the S02 absorption area and the thickeners and filtration equipment in
the solids disposal area.   The higher land and disposal area preparation
costs for the limestone process are due to both the type of disposal
(pond versus landfill) and the nature of the settled sludge in the pond
(i.e., the sludge in the pond is only 40% solids as compared to a dry
product going to the landfill in the generic lime spray dryer process).

            TABLE 16.  SUMMARY OF THE TOTAL CAPITAL INVESTMENTS




Investment area
Material handling
Feed preparation
Gas handling
S02 absorption
Particulate removal
Particulate handling
and recycle
Solids disposal
Disposal area preparation
Land
All other capital costs
Total capital investment
Total cost,
Generic lime
spray dryer
process
2,443
599
7,190
7,173
11,133

1,425
379
321
515
34,993
66,171
, k$
Limestone
slurry
process
919
1,071
9,924
13,734
12,395

-
1,453
3,793
910
48,910
93,189

          Basis:
            TVA design and economic  premises.

 ANNUAL REVENUE REQUIREMENTS

 Generic Lime Spray Dryer Process

      The first-year annual revenue  requirements for the generic lime
 spray dryer process as applied to the previously described base case are
 $17.04M in 1984 dollars as shown in Table 17.   This corresponds to a
 first-year unit revenue requirement of 6.20 mills/kWh.  Equivalent
 levelized annual revenue requirements for the  generic lime spray dryer
 process are $23.52M, or 8.55 mills/kWh.

      Annual direct costs (including raw material and conversion costs)
 are $5.52M or slightly more than 32% of the total first-year annual
 revenue requirements.  Indirect costs, primarily capital charges but
 also including overhead costs, account for the remaining 68%.

      The major direct costs are maintenance ($1.9M), electricity ($1.5M)
 and lime ($1.0M).  Together these three items account for 26% of the
 first-year annual revenue requirements.  The other major annual costs
 are the levelized capital charges of $9.7M and overheads of $1.8M or
 57.1% and 10.5% of the total first-year annual revenue requirements
 respectively.

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                      TABLE 17.   GENERIC  LIME SPRAY  DRYER PROCESS

                                ANNUAL  REVENUE  REQUIREMENTS

                 (500-MW  new  coal-fired  power unit,  0.7% S  in  coal;
                       70% S02 removal; onsite solids disposal)
Annual
quantity
Unit
cost, $
Total
annual
cost, $
Direct Costs - First-Year

Raw materials
  Lime

     Total raw materials cost

Conversion costs
  Operating labor and  supervision
    FGD
    Solids disposal
  Utilities
    Process water
    Electricity
  Maintenance
    Labor and material
  Analyses
  Waste disposal operation

     Total conversion costs

     Total direct costs
    10,068 tons
    25,400 man-hr
    27,040 man-hr

    74,440 kgal
40,151,000 kWh
     4,160 man-hr
   122,500 tons
102.00/ton
 15.00/man-hr
 21.00/man-hr

  0.14/kgal
  0.037/kWh
 21.00/man-hr
  0.15/ton
                                    1,026.900

                                    1,026,900
  381,000
  567,800

   10,400
1,485,600

1,939,400
   87,400
   18,400

4,490,000

5,516,900
Indirect Costs  -  First-Year

Overheads
  Plant and administrative (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 first-year 0 and M)

     Levelized  annual revenue requirements

                                        M$    Mills/kWh

First-year  annual revenue requirements   17.04    6.20
Levelized annual revenue requirements    23.52    8.55
                                   1,796,400

                                   7,313,300


                                   9.727.100

                                  17,040,400


                                  11.792.900

                                  23,520,000
Basis
  Upper  Midwest plant location,  1984 revenue requirements.
  Remaining  life of power plant,  30 years.
  Power  unit on-stream time,  5,500 hr/yr.
  Coal burned, 1,347,000 tons/yr, 9,500 Btu/kWh.
  Total  direct investment,  $32,484,000; total fixed  investment, $50,675,000;  and  total capital
   investment, $66,171,000.
                                              44

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Limestone Slurry Process

     The first-year annual revenue requirements  for the limestone slurry
process are $23.50 as shown in Table 18.   This corresponds to a first-
year unit revenue requirement of 8.55 mills/kWh.   Equivalent levelized
annual revenue requirements are $32.19M or 11.71  mills/kWh.

     Annual direct costs for raw materials, labor, utilities, and main-
tenance are $6.8M, or only 29% of the first-year revenue requirements.
Indirect costs, primarily for capital charges but also including over-
head costs, account for the remaining 71%.

     Raw material costs for the limestone slurry process are about
$0.1M.  The conversion costs are nearly $5.9M, with the major costs
being maintenance and electricity at $3.5M and $1.8M respectively.  As
would be expected, the levelized capital charge at $13.7M was the major
annual expense, representing 58% of the total first-year annual revenue
requirements.

Comparison

     The first-year and the levelized annual revenue requirements for
each of  the FGD processes are shown in Table  19.   The  generic  lime spray
dryer process  is  approximately  27% lower in cost  (6.20 mills/kWh versus
8.55 mills/kWh)  than  the  limestone slurry  process  in terms  of  both
first-year costs  and  levelized  annual revenue requirements.

                   TABLE  19.  BASE-CASE TOTAL FIRST-YEAR

                  AND  LEVELIZED  ANNUAL REVENUE REQUIREMENTS


                                Total  first-year        Levelized annual
                              revenue  requirements
Process
Generic lime spray dryer
Limestone slurry
M$
17.04
23.50
Mills/kWh
6.20
8.55
M$
23.52
32.19
Mills/kWh
8.55
11.71
      Table 20 compares the various component costs of the first-year
 revenue requirements for each process.   The major cost difference
 between the processes is the cost for capital charges, maintenance, raw
 materials, and overheads (primarily because of the differences in main-
 tenance costs).  The $0.7M difference in raw material costs between the
 limestone slurry process and generic lime spray dryer process (limestone
 is much cheaper than lime) is essentially cancelled by the higher capital
 charges of the limestone slurry process.  Utility costs (electricity and
 process water) are about the same for both processes although electrical
 costs are slightly higher for the limestone slurry process.


                                      45

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                           TABLE 18.   LIMESTONE  SLURRY  PROCESS

                                ANNUAL REVENUE REQUIREMENTS

                 (500-MW  new  coal-fired power  unit, 0.7% S  in  coal;
                       70% S02 removal;  onsite  solids  disposal)



Direct Costs - First-Year
Raw materials
Limestone
Total raw materials cost
Conversion costs
Operating labor and supervision
FGD
Solids disposal
Utilities
Process water
Electricity
Maintenance
Labor and material
Analyses
Waste disposal operation
Total conversion costs
Total direct costs

Annual
quantity


15,800 tons



61,900 man-hr
18,720 man-hr

99,670 kgal
47,683,000 kWh


6,240 man-hr
104,500 tons



Unit
cost, $


8.50/ton



15.00/man-hr
21.00/man-hr

0.14/kgal
0.03 7 /kWh


21.00/man-hr
0.15/ton


Total
annual
cost, $


133.900
133,900


928,500
393,100

14,000
1,764,300

3,464,700
131,000
15,700
6,711,300
6,845,200
 Indirect Costs  - First-Year

 Overheads
  Plant and administrative (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  first-year 0 and M)
    Levelized annual revenue requirements
 2,959,800

 9,805,000


13.698.800

23,503,800


18.492.200

32,191,000
                                       M$   Mills/kWh
First-year  annual revenue requirements  23.50   8.55
Levelized annual revenue requirements   32.19  11.71
Basis
  Upper Midwest plant location, 1984 revenue  requirements.
  Remaining  life of power plant, 30 years.
  Power unit on-stream time,  5,500 hr/yr.
  Coal burned, 1,347,000 tons/yr, 9,500 Btu/kWh.
  Total direct investment,  $45,659,000;  total  fixed investment, $71,227,000;  and  total capital
   investment, $93,189,000.

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                     TABLE 20.  SUMMARY OF THE TOTAL

                     FIRST-YEAR REVENUE REQUIREMENTS
     Raw materials
     Operating  labor  and supervision
     Electricity
     Maintenance
     Levelized  capital  charges
     Overheads
     Other annual costs
          Total first-year revenue
          requirements
                                               Total cost, $
                                         Generic lime
                                         spray dryer
                                           process
 1,026,900
  948,800
 1,485,600
 1,939,400
 9,727,100
 1,796,400
   116,200


17,040,400
              Limestone
               slurry
               process
   133,900
 1,321,600
 1,764,300
 3,464,700
13,698,800
 2,959,800
   160,700

23,503,800
     The higher maintenance charge for the limestone process is due to
both the larger number of equipment items needed and the problems
associated with handling and recirculating a corrosive and erosive
scrubbing slurry.
SENSITIVITY ANALYSIS

Sensitivity to Raw Material Prices

     The sensitivity of the first-year annual revenue requirements for
the generic lime spray dryer process and the limestone slurry process to
the delivered raw material cost was calculated.  The results of this
sensitivity analysis are shown in Figure 3.

     Although the generic lime spray dryer process  is more sensitive
than the limestone  slurry process to changes in the delivered price of
the raw material, the low-sulfur nature of the coal and  the  low S02
removal requirement preclude changes from the base-case  costs from
significantly changing the economic results.  The generic lime spray
dryer  process has lower  first-year annual revenue requirements regard-
less of the  raw material prices selected.  For example,  a 25% increase
 (or decrease) in the delivered cost of lime results in only  a  1.3%
increase  (or decrease) in  the first-year annual revenue  requirements  for
 the  generic  lime spray dryer process.  This is still 26.5%  less  than  the
 first-year annual revenue  requirements for  the base-case limestone
 slurry process.
                                     47

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.c-
oo
             10.0
           g  9.0  -
              7.0
              6.0
              5.0
                               LIMESTONE COST, 5/TON

                        5.00           8.50           12.00
                         \              Y
                             Limestone slurry process
                                Generic lime spray dryer process
                          I
                                       I
                        75.00          102.00         125.00
                            LIME COST (DELIVERED), $/TON

          Figure  3.   Sensitivity of  the  first-year annual
                        revenue requirements to  the  delivered
                        cost  of the raw material.
                                                                              10.0
                                                                              9.0
                                                                              8.0
                                                                            5- 6-0
                                                                              5.0
                                                                              4.0
                                                                                          _L
                                                                                                       Limestone slurry process
                                                                                                    Generic lime spray dryer process
                       _L
_L
_L
     0.8       1.0       1.1       1.2       1.3       1.4       1.5
             RAW MATERIAL STOICHIOMETRY,  MOL ALKALI/MOL S02 ABSORBED

Figure 4.    Sensitivity  of  the  first-year  annual revenue
              requirements to  the  raw material stoichiometry
              in  the  absorber.

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     The limestone slurry process,  due  to  the low unit  cost  of  limestone
as well as the lower sulfur level in the coal and the lower  SC>2 removal
requirements, is essentially insensitive to the delivered price of
limestone.

Sensitivity to Raw Material Stoichiometry

     Since the generic lime spray dryer process technology has  only been
demonstrated on a pilot-plant scale, the assumed Stoichiometry  in the
spray dryer could change as the technology is developed further.  In
addition, the alkalinity in the fly ash from low-sulfur coals may vary
between coals.  The required lime Stoichiometry for coals with  the same
sulfur content could change, depending on  the fly ash alkalinity of coal
being burned.  Therefore, a sensitivity analysis showing the changes in
total first-year revenue requirements as the raw material Stoichiometry
in the spray dryer is changed has been included.

     Table 21 lists both the base-case and the alternative stoichio-
metries used in the sensitivity analysis.   The raw material stoichio-
metries given are in mols of alkali per mol of S0~ absorbed.   The range
of stoichiometries shown for the generic lime spray dryer process is
1.00 (-18.0%) to 1.46 (+19.7%).

     The  capital investments for each processing area are adjusted by
using area scale factors and the ratio of  raw material flow rates through
each area.   Processing areas that are sized  independently of the  raw
material  rates  (gas handling and S02 absorption) are the same  for each
of the alternative stoichiometries.  Many  of  the processing areas that
are dependent on the  raw material flow rate  contribute only minor amounts
to the capital  investment.  For  example, a 19.7%  increase in raw  material
flow rate increases the  capital  investment only  about  2%.

     The  annual revenue  requirements for the generic lime spray dryer
process  are  somewhat  more  sensitive to  the raw material  Stoichiometry
than the  raw material cost.  For example,  a 19.7%  increase  in  the raw
material  Stoichiometry results in  a 3.1%  increase  in first-year revenue
requirements.   However,  from these  results (as shown in  Figure 4)  it  is
apparent  that Stoichiometry changes over a wide  range  will  have little
effect  on the capital investment and annual revenue  requirement relation-
ships  of the two  processes.

Sensitivity  to Waste  Disposal  Costs

     An alternate limestone slurry process in which  the  waste  sludge is
dewatered and fixed before disposal in a  landfill is included  for com-
parison purposes.   For  this alternate  process, the front end of the
 limestone slurry process (through  the  venturi/spray  tower absorbers)  is
 identical to the base-case limestone slurry process.  The major difference
 is that the  absorber slurry bleed  is treated using a process similar to
 the IU Conversion Systems, Inc.  (IUCS)  fixation process.  In this process
                                    49

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                    TABLE 21.   COMPARISON OF TOTAL CAPITAL INVESTMENT AND

                  FIRST-YEAR UNIT REVENUE REQUIREMENTS FOR THE GENERIC LIME

                 SPRAY DRYER PROCESS AT VARIOUS RAW MATERIAL STOICHIOMETRIES

Total
Raw material stoichiometry
Process
Generic lime spray
dryer
Limestone slurry
Variation
Low
Base
High
Base
Value*
1.00
1.22
1.46
1.12
% change^
-18.0
19.7
-
capital
$/kW
129.9
132.3
135.0
186.4
investment
% change^
-1.8
2.0
-
First-year unit
revenue requirements
Mills/kWh
6.02
6.20
6.39
8.55
% change^
-2.9
3.1
-

a.  Raw material stoichiometry is defined as mols of alkali per mol of S02 absorbed.
b.  Change is calculated relative to the base-case value.

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the mixed sulfite-sulfate sludge,  rather than being pumped to a pond for
disposal, is dewatered, using a thickener and a filter, to 60% solids,
mixed with dry fly ash and lime, and trucked to an onsite landfill for
disposal.

     The capital investment for this process was estimated from the
base-case limestone slurry process capital investment by deleting the
disposal area preparation (pond construction) and sludge transportation
charges and including the investment required for the IUCS process
equipment and the landfill preparation.  The total capital investment
for the limestone slurry-IUCS process is $91.4M (vs. $93.2M for the
base-case limestone slurry process).  The lower capital investment for
the limestone slurry-IUCS process is the result of the much lower land-
fill preparation costs ($0.23M for the landfill vs. $3.79M for the
pond), which overcome the costs ($2.66M) for the additional equipment
(thickeners and filters).

     The first-year and  the levelized annual revenue requirements for
the limestone slurry-IUCS process are $24.98M (9.08 mills/kWb.) and
$35.20M  (12.80 mills/kWh) respectively.  These costs are about 6% higher
than those for the base  case (i.e., with ponding).  Although  the levelized
capital charges are lower ($0.2M) for the limestone slurry-IUCS process,
this savings is completely offset by the higher labor  costs  ($0.88M)  and
the higher overheads  ($0.62M).
                                    51

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                                REFERENCES
1.  Machine Readable Data Format of FERC FORM 67 Data, 1969-1973,
    Applied Data Research, 1976.

2.  New Stationary Sources Performance Standards; Electric Utility Steam
    Generating Units.  Fed. Regist., 44(113):33,580-33,624, June 11, 1979,

3.  Technical Assessment Guide, EPRI PS-866-SR, Electric Power Research
    Institute, Palo Alto, California, June 1978.

4.  Jeynes, P. H.  Profitability and Economic Choice, 1st Ed., The Iowa
    State University Press, Ames, Iowa, 1968.

5.  Economic Indicators, Chemical Engineering, Vols. 83, 84, 85, and 86,
    1976, 1977, 1978, and 1979.
                                   52

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                               TECHNICAL REPORT DATA
                         (Please read Instructions on the reverse before completing)
 , REPORT NO.
 EPA-600/7-80-050
           J3. RECIPIENT'S ACCESSION NO.
 TITLE ANDSUBTITLE
Preliminary Economic Analysis of a Lime Spray
 Dryer FGD System
           IB. REPORT DATE
            March 1980
           6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)

T.A. Burnett and W.E. O'Brien
           |8. PERFORMING ORGANIZATION REPORT NO.


             EDT-112
 'PERFORMING ORGANIZATION NAME AND ADDRESS
 Tennessee Valley Authority
 Office of Power
 Division of Energy Demonstrations and  Technology
 Muscle ShoalSi Alabama  35660 	
           10. PROGRAM ELEMENT NO.
            INE827
           11. CONTRACT/GRANT NO.
            Inter agency Agreement
            EPA-IAG-D9-E721-BI
 2. SPONSORING AGENCY NAME AND ADDRESS
 EPA, Office of Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC 27711
A T
Pr
            A TYPE OF REPORT A.NB-P.ERLO
              eliminary;
VERED
            14. SPONSORING AGENCY CODE
             EPA/600/13
 -^SUPPLEMENTARY NOTES IERL-RTP project officer is
 919/541-2683.
     Theodore G. Brna, Mail Drop 61,
16. ABSTRACT
              rep0r(. gives results of a preliminary economic analysis of two flue gas
desulfurization (FGD)  processes (one dry and one wet) for a new 500-MW power
plant burning Western coal having 0. 7% sulfur , 9. 7% ash, and a heating value of 9700
Btu/lb and meeting current new source performance standards (70% SO2 removal and
0.03 Ib/MBtu particulate emission). The generic lime spray-dryer process  used a
baghouse for particulate collection, while the wet limestone slurry process had an
electrostatic precipitator (ESP) for particulate control. (In addition to the coal noted,
the final report will include an economic evaluation for both low- and high-sulfur
Eastern coals.) The analysis shows capital investment costs of Sl32/kW for  the lime
process for SO2 and particulate removal, and #186/kW for the limestone process.
First year and levelized annual revenue requirements  are 6. 20 and 8. 55 mills /kW,
respectively, for the lime process; and 8.55 and 11.71 mills /kW, respectively,  for'
the limestone process. Sensitivity analyses  indicate that: (1) delivered  raw material
costs do not significantly affect the annual revenue requirements for either process-
(2) annual revenue requirements for the spray dryer are insensitive to  the raw mat-
erial stoichiometry; and (3) waste disposal for  the wet process, even with fixation,
is more expensive than for the dry process.
 7.
                             KEY WORDS AND DOCUMENT ANALYSIS
                DESCRIPTORS
                                          b.IDENTIFIERS/OPEN ENDED TERMS
                           COSATl Field/Group
Pollution           Calcium Carbonates
Economic Analysis  Spray Drying
Analyzing          Coal
Desulfurization     Combustion
Flue Gases
Calcium Oxides
Pollution Control
Stationary Sources
             13B
             05C      13H
             14B      21D
             07A,07D
             21B
             07B
18. DISTRIBUHON STATEMENT

 Release to Public
19. SECURITY CLASS (ThisReport!
Unclassified
             21. NO. OF PAGES
                75
20. SECURITY CLASS (Thispage)
 Unclassified
                         22. PRICE
EPA Form 2220-1 (9-73)
                                        53

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