EPA-650/2-75-057-Q

June 1975           Environmental Protection Technology Series
                                         SURVEY

                                   OF FLUE  GAS
                 DESULFURIZATION  SYSTEMS

                     CHOUA POWER GENERATING STATION,
                       ARIZONA PUBLIC SERVICE COMPANY
I
55
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                                          ^
SE
                                            UJ
                                            C3
                                  U.S. Environmental Protection Agency
                                   Office of Research and Development
                                        Washington, D. C. 20460

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                                EPA-650/2-75-057.Q
              SURVEY



           OF  FLUE  GAS


DESULFURIZATION  SYSTEMS


   CHOLLA POWER GENERATING STATION,

    ARIZONA  PUBLIC SERVICE COMPANY



                   by

       Gerald A. Isaacs and Fouad K. Zada

      PEDCo-Environmental Specialists, Inc.
                 Suite 13
              Atkinson Square
            Cincinnati,  Ohio 45246
        Contract No. 68-02-1321, Task 6a

             ROAP No. 21ACX-130

          Program Element No. 1AB013
      EPA Project Officer:  Wade H. Ponder



          Control Systems Laboratory

      National Environmental Research Center

      Research Triangle Park, N.  C. 27711
               Prepared for


    U.S. ENVIRONMENTAL PROTECTION AGENCY

    OFFICE OF RESEARCH AND DEVELOPMENT

          WASHINGTON, D.C.  20460


                 June 1975

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                         EPA REVIEW NOTICE

 This report has been reviewed by the National Environmental Research
 Center -Research Triangle Park , Office of Research and Development.
 LPA, and approved for publication.  Approval does not signify that the
 contents  necessarily reflect the views and policies of the Environmental
 Protection Agency, nor does mention of trade names or commercial
 products constitute endorsement or recommendation for use.



                    RESEARCH REPORTING SERIES

 Research reports of the Office .of Research and Development , U.S. Environ-
 mental Protection Agency, have been grouped into series.  These broad
 categories were established to facilitate further development and applica-
 tion of environmental technology.  Elimination of traditional grouping was
 consciously planned to foster technology transfer and maximum interface
 in related fields.  These series are:

           1.  ENVIRONMENTAL HEALTH EFFECTS  RESEARCH

          2.  ENVIRONMENTAL PROTECTION TECHNOLOGY
          3 .  ECOLOGICAL RESEARCH

          4.  ENVIRONMENTAL MONITORING

          5.  SOCIOECONOMIC ENVIRONMENTAL STUDIES

          6.  SCIENTIFIC AND TECHNICAL ASSESSMENT REPORTS
          9.  MISCELLANEOUS
™™  been assi8ned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to
develop and demonstrate instrumentation, equipment and methodology
to repair or prevent environmental degradation from point and non-
point sources of pollution. This work provides the new or improved
technology required for the control and treatment of pollution sources
to meet environmental quality standards.
This document is available to the public for sale through the National
Technical Information Service, Springfield,  Virginia 22161.

                Publication No. EPA-650/2-75-057-a
                                11

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                       ACKNOWLEDGMENT






     This report was prepared under the direction of Mr.



Timothy W. Devitt.  Principal authors were Dr. Gerald A.



Isaacs and Mr. Fouad K. Zada.



     Project Officer for the U.S. Environmental Protection



Agency was Mr. Wade H. Ponder.  Information and data on



plant operation were provided during and subsequent to the



survey visit by Messrs. Cleo Walker and Gilbert Gutierrez,



Arizona Public Service Company, and by Messrs. James E.



McCarthy and Joseph Stites, Research-Cottrell, Inc.  Mr.



Charles D. Fleming was responsible for editorial review of



this report.



     The authors appreciate the efforts and cooperation of



everyone who participated in the preparation of this report.
                             111

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                      TABLE OF CONTENTS

                                                            Page

ACKNOWLEDGMENT                                              iii

LIST OF FIGURES                                              v

LIST OF TABLES                                               v

SUMMARY                                                     vi

1.0  INTRODUCTION                                           1-1

2.0  FACILITY DESCRIPTION                                   2-1

     2.1  Plant Location                                    2-1

     2.2  Boiler Data                                       2-1

     2.3  Pollution Controls                                2-1

3.0  FLUE GAS DESULFURIZATION SYSTEM                        3-1

     3.1  Process Description                               3-1

     3.2  Limestone Milling Facilities                      3-5

     3.3  Process Instrumentation                           3-5

     3.4  Design Parameters                                 3-6

     3.5  Installation Schedule                             3-7

     3.6  Cost Data                                         3-7

4.0  FGD SYSTEM PERFORMANCE                                 4-1

     4.1  Performance Test Run                              4-1

     4.2  Start-up Problems, Solutions and Cost             4-3

     4.3  Process Modifications for Future                  4-7
          Installations

APPENDIX A  PLANT SURVEY FORM                               A-l

APPENDIX B  PLANT PHOTOGRAPHS                               B-l

APPENDIX C  OPERATING DATA                                  C-l

                              iv

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                       LIST OF FIGURES
Figure

 3.1


 3.2
 4.1

 4.2
Process Flow Diagram of the FGD System at
the Cholla Power Plant

Basic Components of Research-Cottrell's
FGD system:  Variable-Throat Flooded-Disc
Particulate Scrubber (foreground) and
SO2 Scrubber Tower  (background)

Scale Buildup in the Flooded-Disc Scrubber

Reheater Corrosion Problem
Page

3-2


3-3
4-4

4-6
Table

 2.1


 3.1

 3.2

 3.3
                       LIST OF TABLES
Pertinent Data on Plant Design, Operation,
and Atmospheric Emissions

Data Summary:  Particulate and SO- Scrubbers

Data Summary:  FGD System Hold Tanks

Typical Pressure Drop Across Components of
Particulate Scrubber and FGD System
Page

2-3


3-8

3-8

3-9
                             v

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                           SUMMARY




     A wet limestone system was designed and installed by



Research-Cottrell for desulfurization of flue gas on Unit 1



of the Cholla Power Generating Station of Arizona Public



Service Company.  This is a base-load unit with a maximum



continuous net generating capacity of 115 MW.  The boiler



burns 54 tons per hour of pulverized coal at capacity.  The



typical gross heat content of the coal, as-received, is



10,290 BTU per pound; typical ash and sulfur contents are



10.4 and 0.55 percent, respectively.



     The flue gas desulfurization system consists of two



parallel scrubbing train modules, each designed to accom-



modate 50 percent of the flue gas.  Module A of the system



includes an adjustable flooded-disc scrubber for particulate



control followed by a packed tower which utilizes a lime-



stone slurry for SO- removal.  Module B also incorporates a



flooded-disc scrubber for particulate control.  Its second



stage absorber shell is similar to that for Module A, but it



contains no packing, and limestone slurry is not circulated



through it.  SO2 removal efficiency for Module B is estimated



by Arizona Public Service to be 25 percent.



     Testing of the system started on October 2, 1973, and



continued until a scheduled shutdown on October 21.  Research-
                               VI

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Cottrell reported that Module A collection efficiencies for particu-



lates and SO2 during that test run were 99.7 percent and 92



percent, respectively.  System availability was reported to



exceed 92 percent.  Official acceptance tests for the



system have not been performed by Arizona Public Service, as



of April 30, 1975.



     After minor modifications the system was officially



started on December 14th and operated with a 92.6 percent



availability factor until April 15th when it was again



brought down for scheduled modifications of the expansion



joints.  Repair crews, supplied by Research-Cottrell, were



available during most of the first half of 1974.  Their



attention to the maintenance of the units partly accounted



for the high availability that was demonstrated during this



shakedown effort.  Modifications were completed by the end



of April, and the system has continued to operate with high



reliability since that time.



     The system operates in an open-loop mode, since there



is no recycling of liquor from the fly ash pond.  Approxi-



mately 386 gallons of make-up water are required per pound-



mole of SO~ removed.



     Installed cost for the flue gas desulfurization system



is reported to be about $6.5 million, or $57 per KW.



Annualized costs are estimated to be 2.2 mills/KWH.  This



figure includes a 23 percent charge on capital investment to



account for interest, depreciation, taxes and other fixed



charges.
                               VI1

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     On December 25, 1974, Research-Cottrell was awarded a



contract for the installation of a similar system on Cholla



Unit 2, where the boiler is under construction.  When this



unit is completed, the plant will have 365 MW of capacity



with SC>2 controls.



     Pertinent data on Unit 1 and on the system operation



are summarized in the following table.
                             Vlll

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           SUMMARY OF FGD DATA, CHOLLA UNIT NO. 1
Unit rating  (net), MW
115
Fuel

  Gross heating value,
  BTU/lb (typ)

  Ash, percent (typ)

  Sulfur, percent  (typ)

FGD vendor

Process

New or retrofit

Start-up date

FGD modules


Efficiency, percent

  Particulates

  SO,,
Water make-up,
  gallons/lb-mole SO2

Sludge disposal
Unit cost, 1973 dollars
Coal


10,290

10.4

0.55

Research-Cottrell, Inc.

Wet limestone scrubbing

Retrofit

October 1973

2 - Only one has packing and
    limestone circulation



99.7 - vendor data

92 - Module A - (vendor data)
25 - Module B - (utility estimate)


386a

Unstabilized sludge disposal in
unlined pond.  Temporary solution
only.

6.5 x 10  (no limestone grinding
or sludge treatment facilities exist)
  Calculated value assuming overall SO- removal efficiency
  of (92 + 25)/2 = 58.5%              *
                               IX

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                      1.0  INTRODUCTION






     The Control Systems Laboratory of the U.S. Environ-



mental Protection Agency (EPA) has initiated a study to



evaluate the status of selected flue gas desulfurization



(FGD) systems on coal-fired boilers in the United States.



This report on the Cholla Power Generating Station of Arizona



Public Service Company (APS) is one of a series of reports



on such systems.  It presents values of key process design



and operating parameters, describes the major start-up and



operational problems encountered at the facility and the



measures taken to alleviate such problems, and identifies



the total installed capital costs and annualized costs.



     This report is based upon information obtained during a



plant inspection on April 2, 1974, and on data provided by



personnel of APS and Research-Cottrell, Inc. (R-C).



     Section 2.0 presents pertinent data on facility design



and operation, including actual and allowable particulate



and SO2 emission rates.   Section 3.0 describes the FGD



system and Section 4.0 analyzes FGD system performance.



Appendices present details of plant and system operation and



photographs of the installation.
                            1-1

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                  2.0  FACILITY DESCRIPTION




2.1  PLANT LOCATION



     The Cholla Power Generating Station of APS is located



near Joseph City, in Navajo County, Arizona.  The terrain



around the Cholla Station is relatively flat and practically



arid; there is no major industry in the area.  The nearest



sizable populated area is the town of Holbrook, about 10



miles east of the plant.



2.2  BOILER DATA



     At present Cholla operates only Unit 1, having a dry-



bottom, pulverized-coal-fired boiler with a net 115 MW



generating capacity.  The boiler was designed by Combustion



Engineering, Inc. (CE).  Plant capacity will increase to 365



MW upon completion of Cholla Unit 2, a 250 MW unit that is



under construction.



     The coal now being burned has typical fuel values, as-



received, of 10,290 BTU/lb, 10.4 percent ash and 0.55 per-



cent sulfur.



2.3  POLLUTION CONTROLS



     A R-C multicyclone-type collector, operating with an



efficiency of about 75 percent, provides primary control of



particulate emissions.  Design particulate loading at the
                              2-1

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outlet of the multicyclones is approximately 2.0 grains per



standard cubic foot (gr/scf).



     The maximum particulate emission allowed under Arizona



State Department of Health Regulation No. 7-1-3.5 is 0.196



Ib/MM BTU of heat input to the boiler.  The present atmo-



spheric emission of particulate from Cholla's FGD system is



reported by APS to be 0.026 Ib/MM BTU.



     Atmospheric emission of sulfur dioxide is limited by



Regulation No. 7-1-4.2 to 1.0 Ib/MM BTU heat input to the



boiler.  The present SO2 emission rate from Cholla Unit 1,



based on a combined 58.5 percent removal efficiency in the



FGD system, is estimated to be 0.36 Ib/MM BTU.



     APS plans to install an FGD system on Cholla Unit 2,



presently under construction.  APS recently signed a contract



with R-C to purchase a particulate scrubber and an FGD



system for that boiler similar to the system on Unit 1.  R-C



is preparing preliminary engineering designs and plans to



use two modules to treat the flue gases from that boiler.



     Table 2.1 presents pertinent data on plant design,



operation, and atmospheric emissions.
                             2-2

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         Table  2.1  PERTINENT  DATA  ON PLANT DESIGN,


              OPERATION,  AND ATMOSPERIC EMISSIONS
     Boiler Data
Rated generating capacity, MW

Average capacity factor (1973)

Served by stack No.

Boiler manufacturer

Year placed in service

Max. coal consumption, T/hr

Max. heat input, MM BTU/hr

Stack height, ft above grade

Flue gas rate-max., acfm

Flue gas temperature, °F

Emission controls

  Particulate


  so2


Particulate emission rate

  Allowable, Ib/MM BTU

  Actual, Ib/MM BTU

SO. emission rate

  Allowable, Ib/MM BTU

  Actual, Ib/MM BTU
       115



        1

       CE

      1962

       54

      1,112

       250

     520,000

       276
  multicylones
venturi scrubber

venturi scrubber
 absorber tower
      0.196

      0.026



       1.0

       0.5 (est.)
 250
 CE
0.167
 0.8
a Boiler under construction.  Contract signed with  Research-Cottrell
  to install a particulate control and FGD system.
                                   2-3

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            3.0  FLUE GAS DESULFURIZATION SYSTEM






3.1  PROCESS DESCRIPTION



     The FGD system consists of two scrubbing trains, labeled



A and B as shown in Figure 3.1, each with a venturi scrubber



for particulate emission control and an absorber tower for



SO2 control.  However, the absorber B-side tower is not



packed and limestone slurry is not circulated through it.



Each train treats about half of the total flue gas from the



coal-fired boiler or about 260,000 acfm at 276°F.  Flue gas



from the boiler induced-draft fans is pressurized by two



booster fans to a static pressure of about 25 in. H-O.  The



flue gas then enters the flooded-disc particulate scrubber



and flows downward through the scrubber throat.  Limestone



slurry flowing out over the disc is atomized as it is sheared



by the gas stream at the edge of the disc.  Limestone slurry



is also injected tangentially through nozzles located on the



inside wall of the scrubber shell near the tapered throat.



The gas pressure drop and the resulting scrubbing efficiency



are regulated by raising or lowering the flooded disc to



vary the throat opening.  Scrubber components are illustrated



in Figure 3.2.



     Gas from the particulate scrubber enters the SO2



absorber near the base of the tower and comes in contact
                             3-1

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LIMESTONE SLURRY MAKEUP
                                                                                          SO; SCRUBBER

                                                                                          OEMISTER

                                                                                               PARTICULATE
                                                                                               SCRUBBER
                                                                                            MODULE (B)
                                                                                       ASH-LADEN

                                                                                        WATER

                                                                                  PURGE TANKJ      [SURGE TANK)
                                                                                                                         FLUE
                                                                                                                         CAS
BOOSTER
  FAN
                                                                                                            TO SlUDCE POND
                               Figure 3.1   Process  flow diagram of  the  FGD  system

                                               at  the Cholla Power  Plant.

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    Figure 3.2  Basic components of Research-Cottrell's
   FGD system: variable-throat flooded-disc particulate
scrubber (foreground) and SO,, absorber tower (background)
                              3-3

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with limestone slurry on the surface of a two-foot-thick



fixed packing.  The packing is made of corrugated sheets of



polypropylene joined in a honeycomb pattern.  Only Module A



is equipped with this packing.  The scrubbed gas then passes



through two plastic one-foot-thick demisters, sections of



which are washed intermittently with fresh water.



     The cleaned flue gas is reheated from 121° to about



165°F as it passes across two bundles of shell-and-tube



heat exchangers.  The source of heat is high-pressure steam



from the boiler steam drum, which is reduced from 1900 psig



to 250 psig.  The reheated gas then exits through a



brick-lined concrete stack, which is common to both trains.



The two trains also share a common S0_ absorber tower recir-



culation tank.



     The rate of limestone addition to the FGD system is



about 110 percent of the stoichiometric rate for reaction



with the sulfur dioxide in the stack gas.  Part of the



circulated liquor in the S02 absorber is diverted to the



flooded-disc scrubber tank  (common to both trains) to main-



tain the pH between 6 and 7 in the particulate control



system.  The liquid level in this tank is maintained by



pumping the excess spent liquor to one of two surge tanks



before it is discharged to the fly ash pond.



     The plant has no equipment for sludge treatment or



fixation.  Because of light rainfall and a high evaporation



rate in this area no liquor is recirculated from the pond.
                               3-4

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     The B-side train can be bypassed in conjunction with A-



side operation, or both trains can be bypassed simultaneously,



However, it is not possible to bypass the A-side train



alone, except for short periods of time.  This is because



limestone enters the system via the A-side absorber and is



used to control the operating pH of the entire particulate



scrubber system.  The inlets to both trains from the booster



fans are interconnected through a common suction header,



which makes it possible to equalize the gas load to the two



trains.



3.2  LIMESTONE MILLING FACILITIES



     Ground limestone for the FGD system is purchased from



two suppliers, both located in Arizona.  The APS limestone



specification calls for material that is at least 75 percent



by weight less than 200 mesh.  Specified minimum CaO is 52.5



percent; specified maximum MgO is 2 percent.



     Because the plant has no limestone milling facility,



the finely ground limestone is stored in a silo.  A small



limestone slurry mixing tank is provided at the base of the



tower.  Limestone milling facilities may be installed after



installation of the FGD system on Unit 2.



3.3  PROCESS INSTRUMENTATION



     Instrumentation of the FGD installation is housed in



two separate areas.  Most of the recording instruments are



mounted on a panel located in the electrical switch gear



building adjacent to the FGD structure.  The remaining



instruments, primarily for remote control of process op-
                              3-5

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erations, are housed in the main boiler control room and are



monitored by the boiler control operator.



3.4  DESIGN PARAMETERS



     The FGD system at the Cholla Station was designed by



R-C to process 480,000 acfm of flue gas at 276°F.  The



actual total flow to both FGD trains, at 115 MW generating



capacity is 400,000 acfm, with about 17,000 acfm of bypass



leakage around the FGD system.



     Each flooded-disc particulate scrubber operates with a



liquid recirculation rate of about 2170 gpm at full load.



This represents a liquid-to-gas ratio  (L/G) of 10.1 gallons



of water per 1000 actual cubic feet  (acf) of gas at 122°F.



Two-thirds of this liquid is introduced into the scrubber



through the hollow shaft of the flooded disc and the remainder



is sprayed through tangential nozzles on the vessel wall.



     The sulfur dioxide absorber tower operates with an L/G



of about 49 gallons/1000 acf.  The design gas velocity



through the tower is 7.7 feet per second.



     Each tower demister is divided into four sections.



Each section is sprayed sequentially with process water for



12 seconds every 8 minutes.  Flow rate of the process water



spray is about 240 gpm.



     The shell-and-tube reheater on each train consists of



two bundles.  The reheater duty is about 8 MM BTU/hr.  Six



steam operated soot blowers for cleaning of the reheater



tubes are operated for 5 minutes during each 8-hour shift.
                              3-6

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     Tables 3.1, 3.2, and 3.3 summarize operating design



parameters and specifications for major components of the



FGD system.



3.3  INSTALLATION SCHEDULE



     Work on the FGD system at the Cholla Station was initiated



in January 1971.  R-C, who already had a pilot plant in



operation at the Cholla Station and was treating a slip



stream from Boiler 1, made a preliminary design and submitted



a proposal for the FGD system in April 1971.  APS awarded



the contract to R-C in July 1971.  Construction and initial



testing of the system were completed on December 3, 1973,



and commercial operation began December 14, 1973.



     System installation was delayed for several reasons,



including engineering design changes, material specification



changes, equipment delivery delays, adverse weather conditions,



and system shakedown problems.



3.6  COST DATA



     The installed cost of this FGD system to APS was about



$6.5 million (equivalent to $57/net KW).  This figure,



however, does not include the cost of such items as limestone



storage and milling facilities and sludge disposal (the



present ash pond is used).  Additional costs incurred by R-C



have not been reported.



     Cost of the ground limestone is $19.20 to $23.50 per



ton, delivered; transportation cost is $7.07 to $15.58 per



ton, ranging from 37 to 66 percent of the delivered lime-



stone cost.
                              3-7

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         Table  3.1   DATA SUMMARY:   PARTICULATE AND SO2 SCRUBBERS
                              Flooded-disc
                                scrubber
                          SO_  absorber
                               tower
L/C ratio,
 gallons/1000 acf

Superficial gas
 velocity, ft/sec

Equipment sizes

Equipment internals
      10.1
6 ft dia.  x 45  ft

 adjustable disc
        48.9


Design 7.7/Actual 6.9


22 ft dia. x 70 fta

     2 ft fixed
   matrix packing
  Estimated
            Table 3.2  DATA SUMMARY:  FGD SYSTEM HOLD TANKS

Total number of
tanks
Tank sizes


Retention time at
full load
Temperature, °F
PH
Solids concentra-
tion, %
Specific gravity
Flooded disc
scrubber
holdup
tank
1

12 ft 6 in.
dia. x 14 ft
6 in.
7 min.

121
5.2
15.5

1.102
S0_ absorber
towers
holdup
tank
1 (common)

27 ft 4 in.
dia. x 28 ft

5 min.

121
6.5
8.3

1.049
FGD system
sludge
holdup
tank
2

18 ft 6 in.
dia. x 27 ft

14 hr ea.

121
5.2
25


Limestone
slurry
makeup
tank
1




_

90

20


                                    3-8

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      Table 3.3  TYPICAL PRESSURE DROP ACROSS

 COMPONENTS OF PARTICULATE SCRUBBER AND FGD SYSTEM
       Equipment                        Pressure drop,
                                         inches  W.G.

Flooded-disc scrubber                      10

SO2 scrubber tower                          0.5

Demister                                    0.5

Reheater                                    3.3

Ductwork                                    4.35

Total system (particulate & SO2 removal)   20
                         3-9

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     Annualized cost for the system is estimated to be 2.2



mills/KWH.  This figure includes a 23 percent charge on



capital investment to account for interest, depreciation,



taxes and other fixed charges.
                               3-10

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                 4.0  FGD SYSTEM PERFORMANCE





4.1  PERFORMANCE TEST RUN



     Initial testing of the FGD system began on October 2,



1973.  The system operated until the scheduled shutdown date



of October 21.  During the 3-week test period, particulate



and SO, removal efficiencies, mist carryover from the towers,



maximum process gas flow rates, and bypass gas leakage rates



were determined.



     Module A consists of a flooded-disc scrubber followed



by a packed tower.  Vendor data indicated an SO2 removal



efficiency of 92 percent with average inlet and outlet SO2



concentrations of 417 and 34 ppm, respectively.  APS estimates



that the S02 removal efficiency for Module B is 25 percent.



Thus the estimated combined SO2 efficiency for the two



modules is 58.5 percent.



     Mist carryover from Modules A and B was nil.  The



solids carryover, detected as calcium ion, averaged 0.005



gr/scf from Module A.  The appearance of the demisters at



shutdown on October 21, 1973, and the carryover tests



indicated very little entrainment of slurry.  Pressure drop



buildup across the demister was less than 0.7 in. H2O over



a 4-month period of operation.



     The maximum average inlet gas rates during the 3-week



operation were 214,300 acfm to Module A and 204,600 acfm to






                               4-1

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Module B, with 18,400 acfm air leakage into the system



downstream of the flooded-disc scrubbers.



     Chloride ion concentrations in the flooded-disc scrubber



recirculation and in tower slurries were 1600 and 575 ppm,



respectively.  These levels are sufficient to cause pitting



corrosion in localized areas with temperatures greater than



140°F and pH less than 3.0.  The chloride content of the



coal ranges between 0.01 to 0.04 percent (equivalent to 8 to



32 ppm by weight in the flue gas).  The chloride ion concentra-



tion in the boiler water blowdown which is used as make-up



water to the FGD unit is 933 ppm.  The chloride ion concen-



tration in the well water, used for boiler make-up water, is



144 ppm.



     Additional vendor data on the 3-week initial operation



are presented in Appendix C.



     The FGD system performed satisfactorily from December



15, 1973, to April 15, 1974.  Although several upsets caused



shutdown of one or both modules for short periods, system



availability averaged 92.6 percent during that period.



     The FGD units were shut down for short periods in April



to replace corroded' Corten steel expansion joints on the



reheater bundles.  Module B was down from April 15 until



April 28; Module A was down from April 17 until April 27.



     As of March 1, 1975 the FGD system has operated satisfac-



torily for 14 months with an average availability factor of



about 92 percent for each module.
                              4-2

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4.2  START-UP PROBLEMS, SOLUTIONS AND COST



     An analysis of the problems encountered during start-up



indicates that nearly all were due to mechanical design



rather than to process chemistry.  An account of the major



problems follows.



     1.  Scale deposits;  Scale accumulated on top and



inside the cavity of the shaft's stuffing box in the flooded-



disc scrubber, as illustrated in Figure 4.1.  These scale



deposits were discovered early enough to prevent binding of



the shaft.  The problem was solved by modifying the assembly



of the stuffing box; it was disassembled, cleaned, and



reinstalled inverted so that the cavity is at the bottom and



cannot accumulate solids.  Other minor scale accumulations



on top of the shaft dome and around the tangential nozzles



of the flooded-disc scrubber did not obstruct the flow of



limestone slurry or flue gas through the scrubber.



     2.  Corrosion:  The expansion joints above the reheaters



of Modules A and B were corroded by the weak sulfurous acid



condensate.  Corrosion was also observed on the top row of



tubes near the tube sheet on Module B.  The cause in all



cases was the accumulation of weak acid condensate in stagnant



pockets in the reheater and ductwork.  To prevent recurrence



of this problem, the ductwork upstream of the reheaters on



Modules A and B was insulated and the Corten steel expansion



joints were replaced with rubber expansion joints.  Also, to



prevent acid condensate from reaching the tubes, a trough



was installed to divert any condensate from the tube bun-
                              4-3

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  TANGENTIAL
 SPRAY  NOZZLE
SCALE  BUILDUP
                                                          CORROSION
                                                             AND
                                                           EROSION
                                                      EROSION
                                                       AND
                                                       LEAKS
           PROBLEM:    SCALE BUILDUP AROUND FDS SHAFT
                      STUFFING BOX.  COULD FREEZE SHAFT
                      MOVEMENT.

           SOLUTION:   STUFFING BOX REINSTALLED IN
                      INVERTED POSITION.
    Figure 4.1   Scale  buildup,  erosion  and corrosion  in
                   the flooded disc scrubber.
                                  4-4

-------
dies.  The corroded tube bundle was replaced.  Figure 4.2



shows the site of the acid condensate corrosion attack.  It



is important to note that corrosion of the reheater by



sulfurous acid occurred only in Module B  (the module without



packing) which has low SO_ removal efficiency.  Presumably



the higher S02 removal efficiency of the packed tower pre-



cludes significant formation of sulfurous acid.  Evidence of



chloride attack was noted in the absorber tower shell.  To



remedy this problem R-C coated the interior of the vessel



with an epoxy material.  This material eroded away below the



scrubber disc.  Alternate lining materials such as brick and



rubber are being considered.  The spray distribution cap above



the flooded disc eroded and corroded completely off.  The cap



is being redesigned by R-C.  Additional chloride attack has



been observed on the B-side reheater tubes.  It is believed



that the chlorides are being introduced in the well water



used in preparing make-up slurry.  The chloride contents of



the coal and of the flue gas are extremely low.



     3.  Vibrations;  Harmonic vibrations with deflections



of as much as 0.040 inch occurred in the reheaters.  The



vibrations were attributed to inadequate transition of duct



size from the absorber outlet to the reheater shell, with a



resultant vortex effect.  To remedy the situation, cross



baffles were installed at the entrance to the reheater.



     Vibrations also occurred in the booster fan on Module



B.  The vibration was caused by uneven buildup of scale on



the fan blades while the unit was idle.  The blades were



sandblasted, cleaned, and rebalanced.




                               4-5

-------
                                        DIRECTION
                                       OF GAS FLOW
CORROSION OF
EXPANSION JOINT
DUE TO ACID
CONDENSATE
                                        FROM SO,
                                                 4
                                       SCRUBBER
                                            I
  CORROSION OF TUBES
DUE TO ACID CONDENSATE
                                        TO  STACK
         PROBLEM:   CORROSION  DUE  TO ACID CONDENSATE

         SOLUTION:  1)  REPLACEMENT OF CORTEN STEEL EXPANSION  JOINTS
                      WITH  RUBBER EXPANSION JOINTS.

                   2)  INSULATION  OF DUCTWORK UPSTREAM OF  REHEATER.

                   3)  INSTALLATION OF TROUGH SECTION ABOVE TUBES TO
                      DIVERT  ACID AWAY FROM TUBE BUNDLE.
                Figure 4.2  Reheater  corrosion problem.

                                     4-6

-------
     4.  Miscellaneous problems;  Buildup of sediment



occurred several times in dead spaces in pipelines and



valves of idle pumps and also in process lines during



periods of reduced operating rate when slurry velocities in



the pipe were low.  The solution to this problem was to



redesign some pipes to eliminate potential dead pockets.  To



prevent freezing of valves due to sediment buildup, some



valves were repositioned and washout lines were installed.



     Some pipe liners eroded.  The erosion was due in some



cases to unsatisfactory liner materials and in other cases



to high velocities through pipes and fittings.  Piping



modifications helped to reduce the erosion problem.  Crack-



ing of the rubber lining in some pipes was due to defects in



fabrication.



     In recent months while burning low-grade coal having



22 percent ash and 0.7 percent sulfur, some plugging of the



tower packing has occurred.  It has not yet been verified



whether or not this plugging is due to the coal grade.  If the



buildup of material in the packing continues, it appears that



the packing life will be reduced to about six months.



4.3  PROCESS MODIFICATIONS FOR FUTURE INSTALLATIONS



     Research-Cottrell, Inc., designer of the wet limestone



FGD system at the Cholla Station, indicates no major changes



in the design of future installations.  Because of reheater



tube failures at the Cholla Station however, reheater units



in future installations will be fabricated of Incoloy,



rather than stainless steel.
                              4-7

-------
   APPENDIX A




PLANT SURVEY FORM
      A-l

-------
                     PLANT  SURVEY FORM3

              NON-REGENERABLE FGD PROCESSES



A.  COMPANY AND  PLANT  INFORMATION

    1.  COMPANY  NAME          Arizona Power Service Co.

    2.  MAIN  OFFICE           	
     3 .  PLANT MANAGER         Cleo Walker
     4 .  PLANT NAME           _ Cholla Power .Generating Station

     5.  PLANT LOCATION         Near Joseph City, Arizona	

     6 .  PERSON TO CONTACT FOR  i'URTHER INFORMATION	

     7.  POSITION                             	

     8.  TELEPHONE NUMBER                    	
     9.  DATE  INFORMATION  GATHERED           	April 2, 1974

    10.  PARTICIPANTS  IN MEETING                 AFFILIATION

          James E..	McCarthy	             Research-Cottrell

          George Wilcox	             Research-Cottrell	

          Wade H. Ponder  	               EPA	
          Timothy W. Devitt	             PEDCo-Environmental

          Fouad K. Zada                      PEDCo-Environmental
a These data were obtained from Research-Cotrell on April  2,  1974
  Some of the data have been updated  in  the text of the report.
                              A-2                 5/17/74

-------
B.  PLANT DATA.  (APPLIES TO ALL BOILERS AT THE PLANT).
CAPACITY, MW
SERVICE (BASE, PEAK)
FGD SYSTEM USED
BOILER NO.
1
115
Base
jimeston
2
Under Cc

>
3
nstructi



Dn






C.  BOILER DATA.  COMPLETE SECTIONS  (C) THROUGH  (R) FOR EACH
    ~~BOILER HAVING AN FGD SYSTEM.
     1.  BOILER IDENTIFICATION NO.

     2.  MAXIMUM CONTINUOUS HEAT INPUT
1112
                                                   124
     3.  MAXIMUM CONTINUOUS GENERATING CAPACITY

     4.  MAXIMUM CONTINUOUS FLUE GAS RATE.    520,000

     5.  BOILER MANUFACTURER             Combustion Engineering
 MM BTU/HR

 MW

ACFM @ 276
     6.  YEAR BOILER PLACED IN SERVICE   May 1962
     7.  BOILER SERVICE  (BASE LOAD, PEAK, ETC.)

     8.  STACK HEIGHT

     9.  BOILER OPERATION HOURS/YEAR  (197 )

    10.  BOILER CAPACITY FACTOR *

    11.  RATIO OF FLY ASH/BOTTOM ASH
     Base
     250 ft.
      * DEFINED AS:  KwH GENERATED IN YEAR
                     MAX. CONT. GENERATED CAPACITY IN KW x  8760 HR/YR
                               A-3
                                                  5/17/74

-------
D.  FUEL DATA

    1.  COAL ANALYSIS  (as received)

             GHV  (BTU/LB.)

             S %

             ASH  %
Dry Basis Avg. as Rec'd.
MAX.




12146
0.52
12.3
AVG.
10290
0.44
10.4
    2.  FUEL OIL ANALYSIS  (exclude  start-up  fuel)

             GRADE                      	

             S %                        	

             ASH %
E.  ATMOSPHERIC EMISSIONS

    1.  APPLICABLE EMISSION  REGULATIONS

        a)  CURRENT REQUIREMENTS

            AQCR PRIORITY CLASSIFICATION

            REGULATION & SECTION  NO.

            MAX. ALLOWABLE EMISSIONS
            LBS/MM BTU

        b)  FUTURE REQUIREMENTS,
            COMPLIANCE DATE

            REGULATION & SECTION  NO.

            MAXIMUM ALLOWABLE  EMISSIONS
            LBS/MM BTU
PARTICULATES


7-1-3.5
0.336
so2


7-1-4.2
1.0
    2.  PLANT PROGRAM FOR PARTICULATES COMPLIANCE
    3.  PLANT PROGRAM FOR SO2  COMPLIANCE
                                A-4
 5/17/74

-------
p.  PARTICULATE REMOVAL

    1.  TYPE

        MANUFACTURER
        EFFICIENCY: DESIGN/ACTUAL    /75

        MAX. EMISSION RATE*  LB/HR

                            GR/SCF

                          LB/MMBTU
MECH.
(multiclones
Research— Cotti
/75
R
F 2.0
IT
E.S.P.
)

_
-

FGD
Wet limestone
qfl.fi/QQ ?



        DESIGN BASIS, SULFUR CONTENT
G.  DESULFURIZATION SYSTEM DATA

    1.  PROCESS NAME

    2.  LICENSOR/DESIGNER NAME:

                       ADDRESS:

             PERSON TO CONTACT:

                 TELEPHONE NO.:
wet flv ash/limestone scrubbing

 Research-Cottrell	
 Box  750 Bound Brook
 New  Jersey   08805	

 James  E. McCarthy.	
    3.  ARCHITECTURAL/ENGINEERS, NAME:

                       ADDRESS:   	

             PERSON TO CONTACT:   	

                 TELEPHONE NO.:
    4.  PROJECT CONSTRUCTION SCHEDULE:
                 DATE
        a)   DATE OF PREPARATION OF BIDS SPECS.   January  1971
        b)   DATE OF REQUEST FOR BIDS

        C)   DATE OF CONTRACT AWARD

        d)   DATE ON SITE CONSTRUCTION BEGAN
             April  1971

             July 1971
        e)   DATE ON SITE CONSTRUCTION COMPLETED  December  3,  1973

        f)   DATE OF INITIAL STARTUP              	

        g)   DATE OF COMPLETION OF SHAKEDOWN      	

     *At Max. Continuous Capacity
                               A-5
              5/17/74

-------
    5.  LIST MAJOR DELAYS IN CONSTRUCTION  SCHEDULE AND  CAUSES:

          Design changes because  of  difficulties at Four  Corners  Plant.

          Late equipment deliveries	

          Material of  construction changes	

          Sub-contract declining  job after award	

          Weather conditions	

          Start up problems	
                                                        AThas packing
    6.  NUMBER OF S02  SCRUBBER TRAINS  USED       two   B.  no packing

    7.  DESIGN THROUGHPUT PER TRAIN, ACFM  @ 276°F   240.000	

    8.  DRAWINGS:  1)   PROCESS FLOW  DIAGRAM AND MATERIAL  BALANCE

                   2)   EQUIPMENT  LAYOUT
H.  SO, SCRUBBING AGENT
      ^                                       limestone purchased in
    1.  TYPE                                  ground  form	
                                             a)  U-S.  limestone,  Nelson
    ?   
-------
-J
STRIAM NO.
RATE, tb/hr
ACFM
CPM
PflRTICULATES. Ib/hr
S02. Ib/hr
ItMPfRflTURE. °F
lOTflL SOUDS. -S
SPECIfrCCRftVITV.

•CO

210, nnn

2090
556
278



C21

147,500

102

120



C3)

183,400

102
47
160



CO

210, POO

2090
556
278



CO
,
147, 50C

102

120



CO

183.400

102
280
160



CO

(16



(2



CO

.900)



78}



CO









(jo)


40






C'i)


2350


120
7
' ..

Ciz)









C>3)


2400






STREAM NO.
RATE. Ib/hr
ACFM
CPM
PARTICUIATES. Ib/hr
S02 , Ib/hr
TEMPERATURE. °F
TOTAL SOUDS. °'°
SPECIFIC GRAVITY

CM)
..• .

10,QQQ


120
7.5


(is)
del
f

10T520







2350


120
16


(I?) 1 118)
1

2400







0






(19)


20
' • :•."•., \

120



[2$


32.5


120
7


(21)

-
64
3976 ,
785

16


(22)


0






(23)


(64)
3976
785

16


@
C25)
l
4
|
-

-
^








C26)









I. Representative flow rates based on operating data at maximum continuous load.

-------
J.  SCRUBBER TRAIN SPECIFICATIONS
    1.  SCRUBBER NO. 1
                       (a)
        TYPE   (TOWER/VENTURI)           Flooded disc  2:1  split  disc  to
                                                                 nozzle
        LIQUID/GAS RATIO, G/MCP @ 121 °F  10.1	

        GAS VELOCITY THROUGH SCRUBBER, FT/SEC   	

        MATERIAL OF CONSTRUCTION                	

        TYPE OF LINING

        INTERNALS:

           TYPE (FLOATING BED, MARBLE BED, ETC.)    flooded  disc

           NUMBER OF STAGES                     	

           TYPE AND SIZE OF PACKING MATERIAL    	
   No lining
           PACKING THICKNESS PER STAGE
                                      (b)
           MATERIAL OF CONSTRUCTION,  PACKING:

                                    SUPPORTS:

    2.   SCRUBBER NO. 2 ^

        TYPE (TOWER/VENTURI)

        LIQUID/GAS RATIO, G/MCF @ 121°F

        GAS VELOCITY THROUGH  SCRUBBER, FT/SEC

        MATERIAL OF CONSTRUCTION

           TYPE OF LINING                       	

        INTERNALS:
                                                 Munters  T2-81  Euroform
           TYPE (FLOATING BED,  MARBLE BED,  ETC.)  fixed Honeycomb
Packed Tower, fixed
matrix in (A) train,
no packing in (B) train

   48.9	

Design 7.7/actual 6.9

   316L SS	

   None
          NUMBER  OF  STAGES

          TYPE AND SIZE  OF  PACKING MATERIAL
 Fixed Matrix
a) Scrubber No. 1 is the scrubber that the  flue gases  first
   enter.  Scrubber 2  (if applicable) follows  Scrubber No. 1.
b) For floating bed, packing thickness at rest.
                               A-8
                                                 5/17/74

-------
       PACKING THICKNESS  PER STAGE
                                   (b)
 2' thick
       MATERIAL  OF  CONSTRUCTION,  PACKINGt  Polypropylene

                                 SUPPORTS;  316L  SS	

    CLEAR WATER  TRAY  (AT TOP OF SCRUBBER)

    TYPE                                   None	


    L/G RATIO                            	

    SOURCE OF WATER                     	
     DEMISTER

        TYPE  (CHEVRON,  ETC.)

        NUMBER OF PASSES (STAGES)

        SPACE BETWEEN  VANES

        ANGLE OF  VANES

        TOTAL DEPTH  OF DEMISTER

        DIAMETER  OF  DEMISTER

        DISTANCE  BETWEEN TOP OF PACKING
        AND  BOTTOM OF  DEMISTER

        POSITION  (HORIZONTAL, VERTICAL)

        MATERIAL  OF  CONSTRUCTION

        METHOD  OF CLEANING

        SOURCE  OF WATER  AND PRESSURE

        FLOW RATE DURING CLEANINGS, GPM
 Plastic polypropylene
 Primarv demister T-271
 Secondary dpmi gt-^v T-41
                Primary 1"
two I1  sections Secondary
  1/2"
 Horizontal	

 Polypropylene	
 Sprav top and bottom
 each quadrant	

 Process water.  60 osig

 120
       FREQUENCY AND DURATION OF CLEANING

       REMARKS  	
5.  REHEATER

       TYPE (DIRECT, INDIRECT)
 Shell  and tubes
b) For floating bed, packing thickness  at  rest.
                           A-9
    5/17/74

-------
       DUTY, MMBTU/HR
       HEAT TRANSFER SURFACE AREA SO,FT  3 bundles


       TEMPERATURE OF GAS:  IN  122°F     OUT 182°F


       HEATING MEDIUM SOURCE


            TEMPERATURE & PRESSURE


            FLOW RATE
Stepped down and desuper-
heated 1900 psia steam from
steam drum
  2500 psig saturated
            LB/HR
       REHEATER TUBES, TYPE AND
       MATERIAL OF CONSTRUCTION
  31fiT. ss
       REHEATER LOCATION WITH RESPECT  TO DEMISTER 30 ft. horizonta
       METHOD OF CLEANING
                            6 steam soot blowers
       FREQUENCY AND DURATION OF CLEANING  5 min. every 8 hrs.


       FLOW RATE OF CLEANING MEDIUM 	 LB/HR


       REMARKS 	
6.  SCRUBBER TRAIN PRESSURE DROP DATA


       PARTICULATE SCRUBBER


       SO2 SCRUBBER


       CLEAR WATER TRAY


       DEMISTER


       REHEATER


       DUCTWORK



       TOTAL FGD SYSTEM
                                                 Modules
         A        B
      INCHES OF WATER
       14.75
        0.5
        0.5
        3.3
        4.35
       23.4
15
 0.5
 3.0
 4.75
23.25
                          A-10
                                             S/17/74

-------
    7.  FRESH WATER MAKE  UP  FLOW RATES AND POINTS OF ADDITION

           TO:  DEMISTER	
                QUENCH CHAMBER
                ALKALI  SLURRYING

                PUMP SEALS 	

                OTHER 	
                TOTAL
           FRESH WATER ADDED PER  MOLE OF  SULFUR REMOVED

    8.  BYPASS SYSTEM

        CAN FLUE GAS BE BYPASSED  AROUND FGD  SYSTEMS 	

        GAS LEAKAGE THROUGH BYPASS  VALVE, ACFM  	
K.  SLURRY DATA
    LIME/LIMESTONE SLURRY MAKEUP TANK

    PARTICULATE SCRUBBER EFFLUENT
    HOLD TANK (a)

    SO2 SCRUBBER EFFLUENT HOLD
    TANK (a)
PH

5.2
6.5
%
Solids
varies
15
8
Size
2'jzJ x 4'
12 '6" $ x
14 '2"
27'4" jzJ x
28'
Hold up
time

7 min.
5 min.
L.  LIMESTONE MILLING AND CALCINING FACILITIES:   INDICATE  BOILERS
    SERVED BY THIS SYSTEM.
        TYPE OF MILL (WET CYCLONE, ETC.)

        NUMBER OF MILLS

        CAPACITY PER MILL

        RAW MATERIAL MESH SIZE

        PRODUCT MESH SIZE
    none
                       T/HR
Received as powder
   Note: cost of limestone $18/ton of which $7.74 for transportation
                                  A-ll
                                                  V17/74

-------
        SLURRY CONCENTRATION IN MILL

        CALCINING AND/OR SLAKING FACILITIES

        SOURCE OF WATER FOR SLURRY MAKE UP OR
        SLAKING TANK
M.  DISPOSAL OF SPENT LIQUOR

    1.  SCHEMATICS OF SLUDGE & FLY ASH DISPOSAL METHOD

        (IDENTIFY QUANTITIES OR SCHEMATIC)  	

    2.  CLARIFIERS  (THICKENERS)

           NUMBER                            Tw°	
           DIMENSIONS                        18'-6" * * 27'
           CONCENTRATION OF SOLIDS IN UNDERFLOW	

    3.  ROTARY VACUUM FILTER

           NUMBER OF FILTERS                  None

           CLOTH AREA/FILTER                	
           CAPACITY                 	TON/HR (WET CAKE)

           CONCENTRATION OF SOLIDS IN CAKE  	

           PRECOAT (TYPE, QUANTITY, THICKNESS)   	

           REMARKS 	
    4.   SLUDGE FIXATION

           POINT OF ADDITIVES INJECTION      Hone

           FIXATION MATERIAL COMPOSITION    	

           FIXATION PROCESS (NAME)          	
           FIXATION MATERIAL REQUIREMENT/TONS OF DRY SOLIDS OF SLUDGE
                               A-12               5/17/74

-------
            ESTIMATED  POND  LIFE,  YRS.
            CONCENTRATION  OF  SOLIDS  IN  FIXED  SLUDGE

            METHOD OF DISPOSAL OF  FIXED SLUDGE 	
            INITIAL  SOLIDIFICATION TIME  OF  FIXED  SLUDGE

      5.  SLUDGE QUANTITY DATA

            POND/LANDFILL SIZE REQUIREMENTS, ACRE-FT/YR

            IS POND/LANDFILL ON OR OFFSITE     On-site

            TYPE OF  LINER                  	
            IF OFFSITE, DISTANCE AND COST OF TRANSPORT
            POND/LANDFILL DIMENSIONS AREA  IN ACRES
                                     DEPTH IN FEET

            DISPOSAL PLANS; SHORT AND LONG TERM
N.   COST DATA
     1.   TOTAL INSTALLED CAPITAL COST

     2.   ANNUALIZED OPERATING COST
                                A'13               5/17/74

-------
4.  COST FACTORS
    a.  ELECTRICITY
    b.  WATER
    C.  STEAM  (OR FUEL FOR REHEATING)
    d.  FIXATION COST	___ $/TON  OF  DRY SLUDGE
                                               (pulverized limestone)
    e.  RAW MATERIAL PURCHASING COST   18   $/TON OF DRY SLUDGE
    f.  LABOR:  SUPERVISOR       	JHOURS/WEEK	WAGE
                OPERATOR	          	
                OPERATOR HELPER  	-           	
                MAINTENANCE           •  ••  •"          	
MAJOR PROBLEM AREAS:   (CORROSION, PLUGGING, ETC.)
1.   SO2 SCRUBBER, CIRCULATION TANK  AND PUMPS.
     a.   PROBLEM/SOLUTION 1) erosion of 2"  fibercast T at pump
          discharge.  2)  flow control valve  liner supposed to be
          teflon,  but instead was carbon impregnated plastic, also
          rubber on rubber-lined pipes cracked/ 1 modified pipes,
          replaced T by 90°  elbow and lowered velocity 2. rubber-
          lined piping changed and replaced  control valve (butterfly)
          with teflon-lined  valve.  Cracking  of  rubber lining	
2.   DEMISTERattributed to mfg.defects.

          PROBLEM/SOLUTION   Essential! ly none	
            AP build up about 0.5" - 0.7" H-O in
                                           i
            4 month  period (12/15 - 4/2/74)
3.   REHEATER
     PROBLEM/SOLUTION D  vibration due to size of duct vs. size of
          reheater transition duct, which caused harmonic vibrations
          (-40 mills deflection)  2) tube bundle leaking to acid
          condensation in uninsulated duct/ 1 installed baffles to
          break harmonics 2 replaced one tube bundle(out of 3)due to
          corrosion and installed diverted baffle to draw off acid
                            alia™ Cheater tubes, duct upsteam of
                                              5/17/74
                            A-l 4

-------
     VENTURI SCRUBBER, CIRCULATION TANKS AND PUMPS
     PROBLEM/SOLUTION 1 )  Scaling on  disc,  buildup on shaft,  hasn' t
     caused a problem yet but might  eventually bind  shaft so it
     can't  move,  buildup  in stuffing gland flange and on top of
     spray  dome.   T]  piuggage ot some small lines particularly when
           i nr  nn -roHuced rat~.es  1 nw^y •Flou wol nr-i-   /  also
     settling in  stand by pumps/ 1 reversed packing gland position
     upside  down,  also removed one half of packing gland,  didn't
     need  that much. _

5.   I.D. BOOSTER FAN AND DUCT WORK
     PROBLEM/SOLUTION  1)  vibration problems due to accumulation
     of  scale buildup  while  fan was idle / 1 cleaned fan  and _
     sandblasted  it.
6.   LIMESTONE MILLING SYSTEM OR LIME  SLAKING
     PROBLEM/SOLUTION N/A	
7.   SLUDGE TREATMENT AND DISPOSAL

     PROBLEM/SOLUTION No problem
                          A"15                5/17/74

-------
     8.   MISCELLANEOUS AREA  INCLUDING BYPASS  SYSTEM
          PROBLEM/SOLUTION Vertically mounted valves (stem horizontal!
          scale and sediment buildup in dead space.  Modified valve
          position to horizontal piping and installed wash out lines.
          Have 20 Hilton valves.  They were the only ones that caused
          problems in vertical position.	
P.   DESCRIBE FACTORS WHICH MAY NOT  MAKE  THIS A  REPRESENTATIVE
     INSTALLATION treatment of sludge is understood not to be required due
     to high rate of evaporation in Arizona. Method presumed acceptable to
     Local EPA.  ])  Lack of limestone milling facilities (APS plans to
     install such system when other two boilers are in operation and FGD
     system installed 2) Absence of sludqe treatment & fixation may not
Q.   DESCRIBE METHODS OF SCRUBBER  CONTROT, UNDER  FLUCTUATING be acceptable
     LOAD.  IDENTIFY PROBLEMS WITH THIS METHOD AND SOLUTIONS,  in other
     IDENTIFY METHOD OF pH CONTROL AND LOCATION  OF pH PROBES.    locals.
  R.   CLASriFY WATER LOOP MODE OF OPERATION
       Since no water is recycled to tfre FQQ system f^Qifl the pnnd
       the installation is considered to be operating under
       open water loop conditions.
                                A-16
                                                  5/17/74

-------
   APPENDIX B




PLANT PHOTOGRAPHS
      B-l

-------
Photo No. 1  General view of the flue gas desulfurization
facilities at the Cholla Power Station.  The facilities consist
of two parallel SO2 scrubbing trains (shown on left) with a
common slurry circulation tank (center).  The pulverized lime-
stone is stored in the tall silo shown to the right of the
slurry circulation tank.  Part of one of the two sludge holding
tanks can be seen behind the limestone silo.  The electrical
switch gear and part of the control instruments are housed
inside the building shown in the center.
Photo No.  2  Back view of SO2 scrubbing train A, showing flue
gas ductwork to the boiler I.D. fan and the booster I.D. (to
the right)  as well as the flooded-disc scrubber and the SO,,
absorber tower (at extreme right).   The path of flue gas
through equipment is indicated by arrows.
                             B-2

-------
Photo No. 3  Close up view of the flooded-disc scrubber.  The
cluster of pipes around the throat of the scrubber distribute
the limestone slurry to nozzles located in the walls of the
scrubber vessel near the entrance to the throat.  Limestone
slurry also enters at the base through the scrubber shaft to
the flooded disc near the throat.
                            B-3

-------
Photo No. 4  Inside view at the base of the limestone silo.  The
limestone vibrating hopper is on top of the structure and feeds
controlled quantities of limestone to the slurry mix tank below.
                             B-4

-------
Photo No.  5  View looking south towards upper half of the lime-
stone silo showinq the pneumatic charging line.  The vertical
limestone  dust trap is on the top of the silo.
                             B-5

-------
Photo No. 6  View from top of the boiler structure looking
towards S02 scrubbing train A.  The picture shows the insulated
duct from top of the absorber tower to the reheater unit.  Part
Of the concrete stack appears to the left.
                              B-6

-------
Photo No. 7  View from top of the boiler structure looking
towards S02 scrubbing train B.  The equipment layout of this
train is a mirror image of that of train A.
                              B-7

-------
Photo No. 8
View from top of the boiler structure looking
                                 The reheaters
towards the area between the two SO- trains.
of both trains are shown on opposite sides of the common
concrete stack.  In the center of the picture is the common
suction ductwork for both booster fans.  A motorized bypass
sliding vane-type of valve is shown center-left portion of
the picture.
                             B-8

-------
Photo No. 9  Top view of the common slurry circulation tank
which serves both trains.  The return piping from both absorber
towers can be seen on opposite sides of the tank.  The tank
agitator motor and gear are in the center.
Photo No. 10  Top view of the twin sludge holding tanks
showing the feed lines from both flooded-disc scrubbers to
each sludge tank.  The discharge from the sludge tanks to the
disposal pond is intermittent and through pipes which are
also used for sluicing of fly ash to the pond.
                            B-9

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Photo No. 11  View of battery of ^>O~ absorber  co./^r  feed
pumps.  There are three feed pumps: two are  in operation
serving both towers  through a common discharge header  and
the third is a standby.
                             B-10

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Photo No. 12  View of the main instrument panel located in
the powerhouse main control room.   The panel contains key
instruments and alarms for remote  control of the flue gas
desulfurization equipment.
                             B-ll

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Photo No. 13  View of the auxiliary control panel located in
the electric switch gear building.  The panel shows a sche-
matic flow diagram of the installation and contains mostly
recording instruments.  DuPont's SO2 analyzer which records
the concentration of SO2 into and oQt of the FGD system is
shown to the right of tne instrument panel.
Photo No. 14  View from top of the boiler structure looking
south towards the transformers switchyard.  The railroad
cars which deliver coal to the plant can be seen immediately
behind the switchyard.
                             B-12

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Photo No. 15  View from top of the boiler structure looking west
towards the structure of boilers 2 and 3, which are presently
under construction.  The concrete structures to the left are the
concrete foundations for the steam turbines and generators for
each boiler-.
Photo No. 16  View from top of the boiler structure looking
southeast towards the sludge and fly ash disposal pond located
behind the railroad tracks.  The lake shown in the foreground
provides fresh water to the plant.  The slurry pipe can be
seen near the edge of the lake.
                             B-13


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  APPENDIX C




OPERATING DATA
     C-l

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       Table C-l  RESULTS OF FGD SYSTEM TEST RUNS
                     OF OCTOBER 1973a
Data
Particulate concentration inlet
(gr/SCFD)
Particulate concentration outlet
(gr/SCFD)
SO2 concentration outlet (PPM)
SO2 concentration inlet (PPM)
Data
SO. removal (percent)
Particulate removal efficiency
(percent)
Gas inlet to FDS (ACFM @ T=276°F,
P=27.3"Hg)
Theoretical inlet gas to FDS (ACFM)
Apparent bypass leakage (ACFM @
T=276°F, P=27.3"Hg)
FDS L/G ratio (gal./lOOO ft3)
Tower L/G ratio (gal./lOOO ft3)
Gas velocity through tower (ft/sec)
Mist entrainment from tower (gr/SCFD)
Solids entrainment from tower slurry
(gr/SCFD)
Pressure drop FDS (IWG)
Pressure drop tower demisters (IWG)
Pressure drop reheater (IWG)
Side A
1.995
0.0083
34
417
"A"
Side
92.4
99.7
214,300
198,800
16,
10.1
48.9
6.9
0.000
0.005
14.8
0.00
5.15
Side B
2.537
0.0101
357
409
11 B" Side
with Ring
14.4
99.8
204,600
198,800
900
10.6
0.0
6.6
0.000
N.A.
15.7
0.00
2.30
Stack
-
0.1149
236
—
11 B" Side
without Ring
9.2
99.7
240,300
-
-
5.8
0.0
7.7
N.A.
N.A.
13.5
-
-
Reported by Research-Cottrell.
                              C-2

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Table C-l  RESULTS OF FGD SYSTEM TEST RUNS
       OF OCTOBER 1973   (continued)
Data
Temperature tower outlet (°F)
AT reheater (°F)
Demister water rate (GPM)
Slurry flow to FDS (GPM)
Slurry flow from FDS (GPM)
Limestone feed rate (Ib/min)
Slurry flow from tower tank to FDS
tank (GPM)
Slurry flow from FDS tank to slurry
(GPM)
Tower tank makeup water (GPM)
FDS tank makeup water (GPM)
Specific gravity/percent solids
tower tank
Specific gravity /percent solids
FDS tank
Percent solids FDS tank (be
Dynatrol)
Tower tank pH
FDS tank pH
Coal consumption (tons/hr)
Coal heating value (BTU/lb)
Atmospheric pressure (in. Hg)
"A"
Side
121
65
12.2
2170
1317













"B" Side
with Ring
121
60
14.0
2177
1486
16.6
32.5 (es1
64.0
0
N.A.
1.049/8.3
1.102/14.8
15.5
6.5
5.2
54
10,293
25.3
"B" Side
without Ring
121
60
14.0
1400
N.A.

:.)











                     C-3

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                                 TECHNICAL REPORT DATA
                          (Please read Instructions on the reverse before coin/ilcting)
 1 REPORT NO
 EPA-650/2-75-057-a
                                                       3 RECIPIENT'S ACCESSION NO
 4 TITLE AND SUBTITLE
 Survey of Flue Gas Desulfurization Systems
  Cholla Power Generating Station, Arizona Public
  Service Company	
                                  5 REPORT DATE
                                  June 1975
                                  6. PERFORMING ORGANIZATION CODE
 7. AUTHOR(S)

 Gerald A. Isaacs and Fouad K. Zada
                                                      8. PERFORMING ORGANIZATION REPORT NO
 9 PERFORMING ORGANIZATION NAME AND ADDRESS
 PEDCo-Environmental Specialists, Inc.
 Suite 13, Atkinson Square
 Cincinnati, Ohio  45246
                                                       10. PROGRAM ELEMENT NO.
                                   1AB013; ROAP 21ACX-130
                                  11 CONTRACT/GRANT NO.

                                   68-02-1321, Task 6a
 12. SPONSORING AGENCY NAME AND ADDRESS
 EPA, Office of Research .and Development
 NERC-RTP, Control Systems Laboratory
 Research Triangle Park, NC  27711
                                  13. TYPE OF REPORT AND PERIOD COVERED
                                  Subtask Final: 4/74 -  5/75
                                  14. SPONSORING AGENCY CODE
 15 SUPPLEMENTARY NOTES
 16. ABSTRACT
              repOrt gives results of a survey of a wet limestone system for .desul-
 furization of flue gas on Unit 1 of the Cholla Power Generating Station of Arizona
 Public Service Company (APSCo).  This  base-load unit has a maximum continuous net
 generating capacity of 115 MW.   At capacity, the boiler burns 54 tons of pulverized
 coal per hour.  The typical gross heat content of the coal, as received, is 10,290 Btu
 per pound; typical ash and sulfur contents are 10.4 and 0. 55 percent, respectively.
 The system consists of two parallel scrubbing train modules, each accommodating
 50 percent of the flue gas. Both modules include an adjustable flooded-disc scrubber
 for particulate control, followed by a tower. The module A tower is packed, utilizing
 a limestone slurry for SO2 removal. The module B tower contains no packing, and
 limestone is not circulated through it.  APSCo estimates module B SO2 removal
 efficiency to be 25 percent. The system operates in an open- loop mode, since there is
 no recycling of liquor from the fly ash pond. Approximately 386 gallons of make-up
 water are required per pound-mole of SO2 removed.  Installed  cost for the system
 is reported to be about ?6. 5 million, or $57 per KW.  Annualized costs are  estimated
 to be 2.2 mills /KWHr, including a 23 percent charge on capital investment to account
 for interest, depreciation, taxes, and other fixed  charges.
 7.
                             KEY WORDS AND DOCUMENT ANALYSIS
                 DESCRIPTORS
                                          b.IDENTIFIERS/OPEN ENDED TERMS
                                              c.  COSATI Field/Croup
Air Pollution
Flue Gases
Desulfurization
Limestone
Scrubbers
Coal
Combustion
Cost Engineering
Air Pollution Control
Stationary Sources
Wet Limestone
Particulate
13 B
21B      14A
07A, 07D
                                              21D
 8 DISTRIBUTION STATEMENT


 Unlimited
                      19 SECURITY CLASS (This Report)
                      Unclassified
                        21 NO. OF PAGES
                             63
                      20 SECURITY CLASS (Thispage)
                      Unclassified
                        22 PRICE
EPA Form 2220-1 (9-73)
                                        C-4

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