Conceptual Design and Economics of an Improved Magnesium Oxide

18

Downloaded by FUDAN UNIV on February 19, 2017 | http://pubs.acs.org Publication Date: July 1, 1982 | doi: 10.1021/bk-1982-0188.ch018

Conceptual Design and Economics of an Improved Magnesium Oxide Flue Gas Desulfurization Process T. A. BURNETT and W. L. WELLS Tennessee Valley Authority, Office of Power, Division of Energy Demonstrations and Technology, Chattanooga,TN37401

An improved magnesium oxide (MgO) flue gas desulfurization process and its comparative economics are described. Innovations made include the use of a spray dryer, a cyclic hotwater reheater, and a coal-fired fluidized-bed reactor for regeneration of the MgO absorbent. Several technical concerns with the proposed design are addressed, including fly ash and chloride buildup. The economic evaluation shows the process to have a capital investment of about seven percent less than that of a conventional MgO scrubbing process and a 40 percent smaller annual revenue requirement. Finally, a sensitivity analysis is shown relating annual revenue requirements to the byproduct sulfuric acid price credit.

This chapter not subject to U.S. copyright. Published 1982 American Chemical Society. Hudson and Rochelle; Flue Gas Desulfurization ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

382

FLUE

GAS

DESULFURIZATION


INTRODUCTION TVA's involvement w i t h magnesium oxide (MgO) f l u e gas d e s u l f u r i z a t i o n (FGD) systems extends over a p e r i o d of years and has been documented i n a recent Environmental P r o t e c t i o n Agency symposium paper (V). The process described t h e r e i n u t i l i z e s conventional MgO FGD technology and i s s i m i l a r i n design to one being i n s t a l l e d commercially by P h i l a d e l p h i a E l e c t r i c Company. S i n c e the c o n v e n t i o n a l MgO p r o c e s s has not g a i n e d widespread acceptance, e f f o r t s are underway to make the process more energy e f f i c i e n t , l e s s dependent on f u e l o i l and, most i m p o r t a n t l y , more competitive economically w i t h a limestone scrubbing system. T h i s paper i s the r e s u l t of TVA»s i n i t i a l i n v e s t i g a t i o n i n t o an improved MgO process. The purpose i s to d e s c r i b e the new MgO process, t o d e t a i l some of the t e c h n i c a l u n c e r t a i n t i e s r e q u i r i n g f u r t h e r development work, and to present p r e l i m i n a r y conceptual design economics f o r t h i s improved MgO FGD system. INNOVATIVE DESIGN CHANGES F i g u r e s 1 and 2 , r e s p e c t i v e l y , show the o l d and new processes. The major innovations are use of (1) a spray dryer absorber i n place of the wet v e n t u r i , absorber, c e n t r i f u g e , r o t a r y dryer combination; (2) a c y c l i c hot-water reheat system i n t e r c o n n e c t i n g t h e r m a l l y the c a l c i n e r product s o l i d s and the e f f l u e n t gas from the spray dryer absorber; and (3) a c o a l f i r e d , f l u i d i z e d - b e d r e a c t o r f o r conversion of magnesium s u l f i t e (MgSO ) and s u l f a t e (MgSO^) t o MgO and S 0 gas. Otherwise, tne two systems are very s i m i l a r , u t i l i z i n g a regenerable absorbent to recover the s u l f u r m a t e r i a l as a u s a b l e c o m m e r c i a l grade o f c o n c e n t r a t e d s u l f u r i c a c i d . Spray dryer absorbers have r e c e n t l y been adapted f o r use i n FGD systems by numerous vendors and the r e s u l t i n g lime-based FGD processes have been s o l d f o r v a r i o u s u t i l i t y and i n d u s t r i a l a p p l i c a t i o n s (2). These spray dryer absorbers appear to o f f e r the p o t e n t i a l f o r s i g n i f i c a n t advantages over conventional wet scrubbing technology i n c l u d i n g ( 1 ) e l i m i n a t i o n of stack gas r e h e a t f o r most a p p l i c a t i o n s , ( 2 ) e l i m i n a t i o n of mist e l i m i n a t o r s , (3) production of a dry waste d i r e c t l y , and (4) e l i m i n a t i o n of the l a r g e r e c i r c u l a t i n g pumps and p i p i n g . From a t h e o r e t i c a l standpoint, there does not appear to be any reason why a spray dryer absorber could not be adapted to the MgO FGD process and o f f e r these same advantages. I n f a c t the production of a dry waste d i r e c t l y i n the spray dryer may prove t o be the most s i g n i f i c a n t p o t e n t i a l advantage s i n c e i t w i l l 2

Hudson and Rochelle; Flue Gas Desulfurization ACS Symposium Series; American Chemical Society: Washington, DC, 1982.


MgO ISTORAGEl SILO

1

Figure 1.

{

y

IMgO PRODUCT COOLER

ί

C

y

SPRAYDRYER' RECOVERY CYCLONE

I

~ y

{

ί_ΤΟ

BURNER

FUEL OIL

" - N CENTRIFUGE

FAN INLET PLENUM

RECYCLE LIQUOR TANK

WATER MAKE-UP

RE GE N_E R A T E D__ M g O

S U L F I T E _FEE_D

V7r 'CYCLONES Y

,

ABSORBER RECYCLE TANK

ABSORBER.

ΓΤΤΤΤΠ

IJSULFITE FEED

I COOLING WATER

RECOVERY CYCLONE

-ΛΜΟΟ Π

ι

e

I [

t__r_

_

_J

Mg_0_SjLO ^

Γ"

TO STACK

, liquid/slurry;

C O N V E N T I O N A L , SINGLE • CONTACT SULFURIC ACID P L A N T

ROTARY DRYER

PLENUM

FROM SCRUBBER FANS

III

DISCHARGE

Conventional MgO FGD system process flow diagram. Key: solid; , gas; and (S), spare.

FLUID BED CALCINER

Α Jî

VENTURI BLOWDOWN TO NEUTRALIZATION

ACID PLANT BLOWDOWN

VENTURI RECYCLE TANK

PLENUM

MAKE-UP MgO

SUPPLY

HAMMER ι— —ι MILL UJ

REGENERATED_MgO

PLANT

Aao

FROM »; POWERHOUSE


,


Τ

COMBUSTION

AIR HEATER

ECONOMIZER

Figure 2. Spray dryer MgO FGD system process flow diagram.


CHLORIDE PURGE


18.

BURNETT AND WELLS

385

Magnesium Oxide Desulfurization

e l i m i n a t e those p r o c e s s i n g s e c t i o n s i n the conventional MgO FGD process which consume s i g n i f i c a n t amounts of energy ( i . e . , the scrubber r e c i r c u l a t i o n pumps and the s o l i d s s e p a r a t i o n and d r y i n g equipment). The c y c l i c hot-water reheater system recovers heat from the product s o l i d s c o o l e r i n the c a l c i n a t i o n area and uses t h i s heat t o d i s p l a c e steam i n the stack gas reheater. The f l u i d i z e d - b e d c a l c i n e r i s f i r e d w i t h s t a t i o n c o a l r a t h e r than expensive No. 2 f u e l o i l which was used i n the previous c o n v e n t i o n a l MgO e v a l u a t i o n . Both o f these l a t t e r design changes r e f l e c t new t e c h n o l o g y w h i c h may r e q u i r e some a d d i t i o n a l development work before they are accepted as proven f o r commercial usage.

SPRAY DRYER MgO PROCESS DESCRIPTION As shown i n F i g u r e 2, f l u e gas from the b o i l e r a t about 300°F passes through a 95% e f f i c i e n t ESP t o remove most o f the f l y ash before the f l u e gas enters the FGD system. The c o l l e c t e d f l y ash i s removed from the ESP hopper, t r a n s f e r r e d to intermediate storage s i l o s , and trucked t o an o n s i t e ash l a n d f i l l s i t u a t e d one m i l e from the power u n i t . The f l u e gas from the ESP passes through the b o i l e r ID f a n , a common plenum f e e d i n g the m u l t i p l e t r a i n s o f spray d r y e r s , and the ductwork f e e d i n g the spray dryer. The f l u e gas enters the spray dryer and passes downward through a c o n c e n t r i c r i n g o f t u r n i n g vanes which surround the r o t a r y a t o m i z e r s . The makeup MgO s l u r r y i s pumped to the spray dryer and passes through the i n t e r n a l s o f the r o t a r y atomizer and i s sprayed p e r p e n d i c u l a r l y t o t h e f l u e gas f l o w . The r e s u l t i n g i n t i m a t e mixing o f the f l u e gas and t h e f i n e MgO s l u r r y p a r t i c l e s r e s u l t s i n the f o l l o w i n g primary r e a c t i o n s :

MgO + S 0 - * MgS0

3

(1)

MgO + S0 ~*> MgS0

4

(2)

2

3

MgO + 2HC1 —*· M g C l

2

+H 0 2

(3)


386

FLUE

In addition occur:

the

following

secondary

MgS0 + 1/20 -*MgS0 3

2

GAS

reaction

DESULFURIZATION

i s expected

to

(4)

4


The amount of water i n the makeup MgO s l u r r y t h a t i s pumped to the spray dryer i s c o n t r o l l e d such t h a t the f l u e gas leaves the spray dryer unsaturated. Since no l i q u i d water remains i n the f l u e gas, mist e l i m i n a t o r s are not r e q u i r e d and the magnesium s a l t s leave the spray dryer as dry p a r t i c l e s e n t r a i n e d i n the f l u e gas. The f l u e gas leaves the spray dryer at about 150°F and i s p a r t i a l l y reheated i n a c y c l i c hot-water reheater before e n t e r i n g the baghouse. The water i s heated i n the product s o l i d s c o o l e r i n the c a l c i n a t i o n area and then passed through tubes i n the ductwork between the spray dryer and the baghouse, h e a t i n g the f l u e gas. The f l u e gas i s reheated approximately 20 F* t o prevent condensation i n c o l d spots i n the baghouse. 5

The baghouse i s designed to r e c e i v e f l u e gas from a l l t r a i n s of the spray dryers and to remove the p a r t i c u l a t e matter such that the 1979 NSPS f o r p a r t i c u l a t e matter (0.03 lb/MBtu) i s achieved. The c l e a n f l u e gas from the baghouse passes through an ID f a n and exits through the stack. The bags i n the baghouse are p e r i o d i c a l l y cleaned by reverse a i r and the mixed magnesium s a l t s and f l y ash f a l l i n t o hoppers at the bottom of the baghouse. These c o l l e c t e d s o l i d s are pneumatically conveyed to intermediate storage s i l o s . From these s i l o s the s o l i d s are pneumatically conveyed to a c o a l f i r e d , fluidized-bed calciner. S t a t i o n c o a l i s removed from the p l a n t s t o c k p i l e , ground i n a g r i n d i n g m i l l , and blown i n t o the f l u i d i z e d - b e d c a l c i n e r . The c o a l burns i n the f l u i d i z e d bed of MgO p e l l e t s to produce heat to maintain the r e a c t i o n temperatures. I n s i d e the c a l c i n e r at a temperature of 1600°F the magnesium s a l t s are reconverted to MgO and S O 2 by the following reactions: MgS0

3 ( s )

MgS0 . H 0 4

M

M

S 0

* 4(s)

C 1

* 2(s)

+ H

7

+

2

C

( s )

—

MgO

—MgS0

(s)-^

2°(g)-^

(s)

(5)

+ 7H„0

(6)

4 ( s )

^(s)' M g

+ so.2 ( g )

°(s)

w

'2 (g)

- + SO. 2(g) +

+ CO

(g)

(7) (8)

2HC1

(g)


BURNETT AND WELLS


18.


387

The f l y ash i s assumed t o pass through the c a l c i n e r unreacted. Although MgS03 i s easily calcined a t 1600°F, MgSCty (formed i n e i t h e r the absorber o r the ash purge s e c t i o n ) r e q u i r e s higher temperatures or the presence o f carbon f o r the decomposition r e a c t i o n t o occur. S i n c e carbon i n the form o f c o a l i s present i n the c a l c i n e r , the MgSOij i s assumed t o be c a l c i n e d as shown i n r e a c t i o n 7. The SÛ2-ladened o f f - g a s from the c a l c i n e r c o n t a i n i n g the regenerated HC1 and the e n t r a i n e d MgO and f l y ash passes overhead and i n t o the MgO product c y c l o n e . Approximately 80? of the s o l i d s are removed from the o f f - g a s . S i n c e the p a r t i c l e s i z e s o f the MgO and f l y ash are c o n s e r v a t i v e l y assumed t o be very s i m i l a r , 80$ o f each a r e removed. These hot (1600°F) s o l i d s pass through a product s o l i d s c o o l e r where they a r e cooled t o about 400°F before being pneumatically conveyed t o the r e c y c l e MgO/ash storage s i l o f o r reuse. The heat exchange medium i n the product s o l i d s c o o l e r i s high-pressure water. T h i s hot water passes through the c y c l i c reheater i n the f l u e gas duct between t h e s p r a y d r y e r and t h e baghouse. The SÛ2-ladened o f f - g a s leaves the MgO product cyclone at 1600°F and preheats the incoming a i r t o the c a l c i n e r i n a f l u i d i z i n g a i r heater. The o f f - g a s from the a i r heater a t 880°F i s f u r t h e r cooled t o 440°F i n a spray quench tower and then enters a p u l s e - j e t baghouse where the remaining s o l i d s are removed. (A p u l s e - j e t baghouse i s used because o f the s m a l l gas stream t o be cleaned.) The c l e a n o f f - g a s passes through a f i n a l cleanup s e c t i o n where the 440°F o f f - g a s i s cooled by r e c i r c u l a t i n g water sprays t o condense some o f the water vapor and a l s o t o scrub the HC1 from the o f f - g a s . T h i s HCl-contaminated water passes t o a s t r i p p e r where compressed a i r , passing through the water, removes any remaining SO2 from the water before the water i s n e u t r a l i z e d and pumped t o the c l a y - l i n e d b o i l e r ash pond. The S02-ladened o f f - g a s from the c o o l e r and the a i r from the s t r i p p e r a r e compressed and sent t o a s i n g l e - c o n t a c t , single-absorption s u l f u r i c acid plant. N i n e t y - s i x percent o f the SO2 i s converted t o 98$ s u l f u r i c a c i d . Ten percent o f t h i s byproduct a c i d i s r e c y c l e d and used i n the MgO FGD process but most i s s t o r e d o n s i t e and e v e n t u a l l y s o l d as a byproduct. The t a i l gas from the a c i d p l a n t c o n t a i n i n g the unconverted S0 i s r e c y c l e d t o the f l u e gas ducts ahead o f the FGD system. The s o l i d s from the p u l s e - j e t baghouse a t 440°F a r e p n e u m a t i c a l l y conveyed t o an i n t e r m e d i a t e storage s i l o . About t w o - t h i r d s o f the MgO/ash mixture i s returned t o the r e c y c l e MgO/ash storage s i l o i n the feed p r e p a r a t i o n area w h i l e the remaining o n e - t h i r d enters the ash purge s e c t i o n . I n t h i s sect i o n the MgO/ash mixture i s f i r s t r e s l u r r i e d w i t h water and then mixed w i t h 9 8 ? s u l f u r i c a c i d from the a c i d p l a n t . The 2


FLUE

388 sulfuric acid reacts MgS0i|*7H 0, i . e . ,

with

insoluble

MgO

to

GAS

DESULFURIZATION

form

soluble

2

M

«?s)

+

H

S

2 %aq)

+

6

H

2 ° * ^ V ^ a q )

( 9 )

which can then be separated from the ash by f i l t r a t i o n . The r o t a r y drum f i l t e r separates the ash from the MgSOijîÔ s o l u t i o n . The f i l t e r cake i s washed twice to recover as much o f the d i s s o l v e d MgSOij^ïÔ as p r a c t i c a l before the cake is trucked t o the o n s i t e ash landfill for disposal. The filtrate and the wash water containing the MgS0ij* H20 are pumped to the s l u r r y feed tank i n the feed p r e p a r a t i o n area. V i b r a t i n g screw feeders t r a n s f e r makeup MgO and r e c y c l e MgO/ash from 8-hour c a p a c i t y , in-process feed bins to the prèslake mixer where f r e s h water i s added to wet the MgO thus a l l o w i n g b e t t e r mixing i n the s l u r r y feed tank. Residence time i n the mixer i s only about two minutes to prevent solidification of the concentrated mix. Makeup water as necessary i s added and s l a k i n g i s completed i n the s l u r r y feed tank. The r e s u l t i n g s l u r r y i s pumped to the spray dryer as required.


7

TECHNICAL UNCERTAINTIES T h i s conceptual design and economic e v a l u a t i o n i s based on t h e o r e t i c a l c o n s i d e r a t i o n s only and many of the assumptions used i n t h i s design need to be v e r i f i e d i n an a c t u a l p i l o t plant operation. These various design assumptions i n c l u d e : (1) MgO/ash separation, (2) HC1 removal and purge, and (3) spray dryer design. MgO/Ash Separation The i n i t i a l and perhaps most c r i t i c a l design assumption i s that both the MgO and the f l y ash, which are c a r r i e d out of the c a l c i n e r and i n t o the MgO product cyclone, have the same p a r t i c l e s i z e d i s t r i b u t i o n and d e n s i t y . T h i s design ( i . e . , no p o s s i b i l i t y of p h y s i c a l s e p a r a t i o n of MgO and f l y ash) i s a c o n s e r v a t i v e design assumption and adds complexity to the FGD process. I t r e s u l t s i n the need t o r e c i r c u l a t e l a r g e q u a n t i t i e s of the MgO/fly ash mixture through the spray dryer and the c a l c i n e r . In order to keep the MgO/ash r e c y c l e streams to a reasonable s i z e , the mechanical c o l l e c t o r s i n the main f l u e gas ducts upstream from the SO2 absorber, which were used i n the i n i t i a l d e s i g n because t h e y a r e r e l a t i v e l y inexpensive but yet remove only 80% o f the f l y ash, had to be replaced with the 95% e f f i c i e n t ESP mentioned e a r l i e r .



18.

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389

The FGD waste p a r t i c l e s e n t e r i n g the c a l c i n e r would tend t o be l a r g e r than the f l y ash p a r t i c l e s because the l a r g e r f l y ash p a r t i c l e s are removed i n the 95% e f f i c i e n t ESP l e a v i n g only the s m a l l e r (MO micron) p a r t i c l e s . The FGD waste p a r t i c l e s , although i n i t i a l l y s m a l l , tend t o coalesce i n the spray dryer as the atomized s l u r r y d r i e s . Based on i n f o r m a t i o n from the lime-based spray dryer FGD systems, i t i s estimated t h a t the FGD waste p a r t i c l e s w i l l be on the order o f 50 microns. I f t h i s p a r t i c l e s i z e d i f f e r e n c e between the ash and the MgO p a r t i c l e s i s s t i l l present i n the p a r t i c l e s l e a v i n g t h e c a l c i n e r , the MgO p a r t i c l e s being the l a r g e r o f the two would tend t o be removed i n the MgO product cyclone. The s o l i d s p a s s i n g through the cyclone (and out w i t h o f f - g a s ) would thus be enriched i n the ash p a r t i c l e s . T h i s enrichment would permit smaller recycle streams to be used. I f the MgO and ash p a r t i c l e s a c t u a l l y have a s i g n i f i c a n t d i f f e r e n c e i n d e n s i t y / p a r t i c l e s i z e , t h e ash purge s e c t i o n could be redesigned t o i n c l u d e a s e p a r a t i o n device such as a t h i c k e n e r that could be used t o s p l i t the s o l i d s i n t o an enriched f l y ash stream and one enriched i n MgO. S i n c e the r e c y c l e MgO must be r e s l u r r i e d before e n t e r i n g the spray d r y e r , w e t t i n g t h i s stream would not present any s i g n i f i c a n t problems t o the process. The f l y ash-enriched stream could then be sent to a s m a l l e r ash purge s e c t i o n . Both o f these a l t e r n a t i v e s e p a r a t i o n techniques could be evaluated i n a spray dryer MgO p i l o t p l a n t . I f e i t h e r or both of these t e s t s y i e l d s a t i s f a c t o r y s o l u t i o n s t o the MgO/ash s e p a r a t i o n p r o b l e m , i t might be p o s s i b l e t o r e d u c e t h e investment and revenue requirements s i g n i f i c a n t l y by e l i m i n a t i n g the 95% e f f i c i e n t ESP and r e p l a c i n g i t w i t h a mechanical c o l l e c t o r . Therefore i t may a l s o be necessary t o perform some t e s t work i n a p i l o t p l a n t t o determine the r e l a t i v e d e n s i t i e s and p a r t i c l e s i z e s of the MgO and the ash i n the c a l c i n e r o f f - g a s . HC1 Removal and Purge The spray dryer MgO FGD system i s based on the design assumption t h a t HC1 i n the f l u e gas r e a c t s w i t h MgO i n the spray dryer t o form MgCl2. S 2 > along w i t h the f l y ash and magnesium-sulfur s a l t s , would then be c o l l e c t e d i n the baghouse and conveyed t o the c a l c i n e r . Based on a previous t h e o r e t i c a l study (3) i t i s f u r t h e r assumed t h a t i n the o x i d i z i n g atmosphere o f the c a l c i n e r , the MgCl2 i s converted back t o MgO and HC1. The MgO i s r e c y c l e d and the HC1 remains i n the S02-ladened o f f - g a s u n t i l i t reaches the gas c o o l e r where i t i s removed by the r e c i r c u l a t i n g water sprays. The r e s u l t i n g c h l o r i d e purge water i s n e u t r a l i z e d w i t h a g r i c u l t u r a l limestone and pumped to the b o i l e r ash pond f o r d i s p o s a l . T

h

e

M

C 1


FLUE


390

GAS D E S U L F U R I Z A T I O N

I f the HC1 i s not regenerated i n the c a l c i n e r as i s c u r r e n t l y expected, one o f two design changes must be made and both i n v o l v e purging a MgCl2 s o l u t i o n from the FGD system. The f i r s t a l t e r n a t i v e i s to remove a purge stream from the mixing tank i n the ash purge s e c t i o n a f t e r the MgO/fly ash mixture has been r e s l u r r i e d (but j u s t before the s u l f u r i c a c i d i s added). At t h i s point i n the process MgCl2 would be the only s o l u b l e magnesium compound present, u l t i m a t e d i s p o s a l of t h i s MgCl2 s o l u t i o n , other than i n the b o i l e r ash pond, i s u n c e r t a i n and would r e q u i r e f u r t h e r s t u d y . The second a l t e r n a t i v e i s to i n s t a l l a guard box i n the f l u e gas ducts between the ESP's and the spray d r y e r s . The guard box would c o n t a i n a s o l i d absorbent which would p r e f e r e n t i a l l y remove HC1 from the f l u e gas. When f u l l y saturated the absorbent would be removed and replaced with a f r e s h charge. Although t h i s would e f f e c t i v e l y remove HC1 from the f l u e gas, the MgCl2 purge system would s t i l l be required (although on a smaller s c a l e ) s i n c e HC1 would s t i l l enter the FGD system from the s t a t i o n coal used as f u e l f o r the f l u i d i z e d - b e d calciner. Thus i t would probably be necessary to determine i f the absorbed HC1 i s i n f a c t regenerated i n the c a l c i n e r . Ifit is not, a s i g n i f i c a n t change w i l l have t o be made i n the process design presented here. Spray Dryer

Design

The design f o r the MgO spray dryer-absorber i s based on the data c u r r e n t l y a v a i l a b l e from the lime-based spray dryer systems since data on an MgO-based spray dryer-absorber are c u r r e n t l y not a v a i l a b l e . T h i s assumption i s considered t o be reasonable since both lime and MgO produce an absorbent s l u r r y and both are Group I I element oxides, but p r i m a r i l y because no other data are a v a i l a b l e . The MgO system i s based on a c o n s e r v a t i v e l y designed lime system ( i . e . , a MgO s t o i c h i o m e t r y o f 1.8 moles MgO/mole SO2 absorbed, a 20 F ° a p p r o a c h t o t h e f l u e gas s a t u r a t i o n temperature i n the spray dryer, e t c . ) . A l l o f the spray dryer design c o n s i d e r a t i o n s w i l l t h e r e f o r e have to be evaluated i n a spray dryer MgO p i l o t p l a n t . PRELIMINARY CONCEPTUAL DESIGN ECONOMICS T h i s s e c t i o n presents comparative economic r e s u l t s f o r three processes, v i z . , conventional limestone, spray dryer MgO, and conventional MgO. The r e s u l t s o f any conceptual design and economic e v a l u a t i o n depend on the premises chosen initially. The major design and economic premises used f o r t h i s study are shown i n Table I .


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TABLE I . MAJOR DESIGN AND ECONOMIC PREMISES Premise

Item

500-MW, new c o a l - f i r e d b o i l e r 11,700 B t u / l b , 15.1$ ash, 4$ moisture 3.5$ s u l f u r (dry b a s i s ) 9,500 Btu/kWh 165,000 h r , 30-year l i f e ; 5,500-hr f i r s t - y e a r o p e r a t i o n

Power p l a n t Fuel


Heat r a t e Operating schedule P a r t i c u l a t e removal efficiency SO^ removal e f f i c i e n c y SO^ absorber redundancy Base year C a p i t a l investment Revenue requirements

Revised 1979 NSPS Revised 1979 NSPS One spare t r a i n Mid-1982 Mid-1984

Design Premises The economic e v a l u a t i o n i s based on a f l u e gas c l e a n i n g (FGD and f l y ash) system t o meet the r e v i s e d 1979 NSPS f o r both p a r t i c u l a t e matter and S 0 f o r a new, 500-MW c o a l - f i r e d b o i l e r . The b o i l e r burns a 3·5$ s u l f u r e a s t e r n bituminous c o a l c o n t a i n i n g 15.1$ a s h and having a h e a t i n g value o f 11,700 B t u / l b . The b o i l e r has a heat r a t e o f 9,500 Btu/kWh. The FGD system i s designed w i t h one spare scrubber t r a i n , 50$ emergency f l u e gas bypass around the FGD system, and an o n s i t e l a n d f i l l l o c a t e d one m i l e from the b o i l e r . The o p e r a t i n g schedule s p e c i f i e s a 165,000-hour, 30-year l i f e f o r the b o i l e r and 5,500 hours o f f i r s t - y e a r o p e r a t i o n . 2

Economic Premises The economic e v a l u a t i o n c o n s i s t s o f a study-grade (-20$, +40$) d e t e r m i n a t i o n o f c a p i t a l investment, f i r s t - y e a r annual revenue requirements, and l e v e l i z e d annual revenue requirements. The c a p i t a l investments a r e based on major equipment c o s t s (developed from the f l o w diagram and the m a t e r i a l b a l a n c e ) and f a c t o r e d c o s t s f o r i n s t a l l a t i o n , a n c i l l a r y equipment, and i n d i r e c t investments. The c a p i t a l investments are based on mid-1982 costs. F i r s t - y e a r annual revenue requirements c o n s i s t o f raw m a t e r i a l , o p e r a t i n g , and overhead c o s t s and l e v e l i z e d c a p i t a l


FLUE

392


charges. The l e v e l i z e d annual revenue requirements c o n s i s t of l e v e l i z e d raw m a t e r i a l , o p e r a t i n g , and overhead c o s t s as w e l l as l e v e l i z e d c a p i t a l charges. The l e v e l i z e d raw m a t e r i a l , conversion, and overhead c o s t s are c a l c u l a t e d by u s i n g a l e v e l i z i n g factor of 1 . 8 8 6 . T h i s f a c t o r i s explained i n more d e t a i l elsewhere (_4) and i s based on a 10?/yr discount r a t e , a 6%/yr i n f l a t i o n r a t e , and a 30-year l i f e o f the power u n i t . Revenue requirements (both f i r s t year and l e v e l i z e d ) are based on mid-1984 c o s t s .


Economic E v a l u a t i o n Since t h e MgO spray dryer FGD p r o c e s s collects p a r t i c u l a t e matter as an inherent part of the FGD system, it can be evaluated e i t h e r as a combined p a r t i c u l a t e - S 0 2 removal system or, with the i n c l u s i o n o f an ESP c r e d i t , as an FGD-only process. I n t h i s study the spray dryer MgO process e v a l u a t i o n i s based on the combined particulateSO2 removal system. The p r i m a r y reasons are that the combined system i s e a s i e r t o e x p l a i n and t h a t s i m i l a r evaluations f o r the limestone scrubbing/ESP and conventional MgO/ESP systems are a v a i l a b l e from previous s t u d i e s (2_, 5). The c o n v e n t i o n a l MgO/ESP p r o c e s s c o s t i n f o r m a t i o n from the previous study was updated using area scale factors, relative product and gas r a t e s , etc., to put t h e r e s u l t s on a c o n s i s t a n t b a s i s w i t h t h e c u r r e n t evaluation of the spray dryer MgO process. All three processes are designed as proven technology, though i t i s recognized that there are major d i f f e r e n c e s i n s t a t u s o f development among t h e s e . The spray dryer MgO process i s a new design, as yet unproven even on a small p i l o t - p l a n t s c a l e . The conventional MgO process i s based on 100-MW testing at Philadelphia E l e c t r i c s Eddystone s t a t i o n . The l i m e s t o n e s c r u b b i n g p r o c e s s i s w e l l - d e f i n e d and g e n e r a l l y c o n s i d e r e d proven technology with widespread adoption i n the e l e c t r i c utility industry. In order to account f o r design u n c e r t a i n t y , both MgO processes have a contingency factor of 20 percent as part o f the c a p i t a l investment, while the l i m e s t o n e p r o c e s s has a c o n t i n g e n c y f a c t o r o f o n l y 10 percent. T h i s contingency f a c t o r d i f f e r e n c e accounts f o r approximately half of the t o t a l capital investment difference. 1


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C a p i t a l Investment Results


The c a p i t a l investment f o r the spray dryer MgO FGD process i s $139.5M ($279/kW) i n mid-1982 d o l l a r s w h i l e that f o r a comparable limestone scrubbing/ESP process i s $122.OM ($244/kW) i n mid-1982 d o l l a r s . The c a p i t a l i n v e s t m e n t f o r the c o n v e n t i o n a l MgO FGD process ( i n c l u d i n g p a r t i c u l a t e c o n t r o l ) i s $149.7M ($299/kW) i n mid-1982 d o l l a r s . These c o s t s a r e summarized i n Table I I . F o r f u l l d e t a i l s see Tables A - I , A - I I , and A - I I I i n the Appendix. TABLE I I . CAPITAL INVESTMENT SUMMARY C a p i t a l Investment k$ $/kW Conventional limestone process Spray dryer MgO process Conventional MgO process

121,953 139,497 149,683

243.91 278.99 299.37

Comparison The c a p i t a l investment f o r the spray dryer MgO process i s approximately 14? higher than that f o r the comparable limestone scrubbing process. T h i s i s not an unexpected r e s u l t s i n c e the MgO process i s a regenerable system w h i l e the limestone scrubbing process i s a throwaway system. Of the components which make up the c a p i t a l investment, the d i r e c t area investment f o r raw m a t e r i a l h a n d l i n g , feed p r e p a r a t i o n , gas h a n d l i n g , SO2 a b s o r p t i o n , and w a s t e d i s p o s a l a l l are more expensive f o r the limestone scrubbing process. Because t h e l i m e s t o n e s c r u b b i n g p r o c e s s i s a throwaway system, i t i s not unexpected that the raw m a t e r i a l h a n d l i n g , feed p r e p a r a t i o n , and waste d i s p o s a l areas are more expensive. The gas h a n d l i n g and S 0 a b s o r p t i o n areas a r e more expensive due t o the wet scrubbing design b a s i s f o r the limestone process. More expensive m a t e r i a l s o f c o n s t r u c t i o n and more equipment are needed i n the wet limestone scrubbing process. The spray dryer MgO process contains a r e g e n e r a t i o n s e c t i o n which i n c l u d e s the areas o f c a l c i n a t i o n , o f f - g a s cleanup, s u l f u r i c a c i d p l a n t , and a c i d storage and s h i p p i n g . 2



394

FLUE

GAS

DESULFURIZATION

There are no comparable areas i n the limestone scrubbing process. The $22 m i l l i o n investment f o r these areas i n the MgO process o f f s e t s the lower investment f o r the other p r o c e s s i n g areas. L i k e w i s e , the c a p i t a l investment f o r the spray dryer MgO process i s approximately 7 percent lower than t h a t f o r the conventional MgO scrubbing process ($279/kW v s . $299/kW). The c o n v e n t i o n a l MgO scrubbing process has more equipment, and hence l a r g e r investment c o s t s , p a r t i c u l a r l y i n the areas of c h l o r i d e purge, s l u r r y d r y i n g , and s l u r r y p r o c e s s i n g equipment w h i c h a r e not needed i n the s p r a y d r y e r - b a s e d system. Both the spray dryer MgO process and the c o n v e n t i o n a l MgO process c o n t a i n a r e g e n e r a t i o n s e c t i o n which i n c l u d e s the areas of c a l c i n a t i o n , s u l f u r i c a c i d p l a n t , and a c i d storage and shipping. The r e g e n e r a t i o n s e c t i o n i n the c o n v e n t i o n a l MgO process a l s o contains the d r y i n g area but l a c k s the o f f - g a s c l e a n i n g area. T h i s o f f - g a s c l e a n i n g area i s not necessary i n the c o n v e n t i o n a l process because c h l o r i d e s are removed upstream and very l i t t l e f l y ash enters the system because of the h i g h e f f i c i e n c y ESP and the r e l a t i v e l y c l e a n nature of No. 2 f u e l oil. The c h l o r i d e s are removed i n the o f f - g a s treatment area i n the spray dryer MgO process u t i l i z i n g s m a l l e r equipment at a lower c o s t . The c o n v e n t i o n a l MgO process c o n t a i n s a c h l o r i d e purge area upstream of the FGD system, which t r e a t s the e n t i r e f l u e gas s t r e a m r e s u l t i n g i n a l a r g e r i n v e s t m e n t c o s t . The net e f f e c t of these d i f f e r i n g area investments f o r the two processes i s t h a t the t o t a l d i r e c t investment f o r the spray dryer MgO process i s about 6% lower ($72.0M v s . $76.2M) than t h a t f o r the c o n v e n t i o n a l MgO process. T h i s cost advantage f o r the spray dryer MgO process i s f u r t h e r increased as a r e s u l t of the premise-derived i n d i r e c t investments ( c o n s t r u c t i o n expense, contingency, e t c . , ) and other c a p i t a l investments (allowance f o r s t a r t u p and m o d i f i c a t i o n and i n t e r e s t during c o n s t r u c t i o n ) even though the cost f a c t o r s ( i . e . , percentages) f o r both processes are i d e n t i c a l . The higher d i r e c t investment f o r the c o n v e n t i o n a l MgO process r e s u l t s i n the higher i n d i r e c t investments and other c a p i t a l investments and hence the t o t a l c a p i t a l investment when these f a c t o r s are a p p l i e d . The c a l c i n e r area, although considered proven technology i n other i n d u s t r i a l a p p l i c a t i o n s , i s as yet i n c o m p l e t e l y t e s t e d i n an FGD facility. F u r t h e r compounding t h e q u e s t i o n s concerning the c a l c i n e r i s the f a c t t h a t i n the spray dryer MgO p r o c e s s i t i s a c o a l - f i r e d , f l u i d i z e d - b e d u n i t whose f e a s i b i l i t y and r e l i a b i l i t y need to be demonstrated. In a d d i t i o n the conversion of MgSOg t o MgO and the r e u s a b l e n a t u r e o f the r e g e n e r a t e d MgO in a full-scale u t i l i t y a p p l i c a t i o n are unknown. A form of c y c l i c reheat i s a l s o employed here u t i l i z i n g the waste heat generated i n the MgO


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product c o o l e r t o provide t w o - t h i r d s o f the reheat r e q u i r e d by the f l u e gas ( t h e remainder i s provided by steam). The other areas i n the spray dryer MgO process a r e a l l r e l a t i v e l y proven technology and can be adapted t o the a p p l i c a t i o n e n v i s i o n e d here. Annual Revenue Requirements


Results The f i r s t - y e a r annual revenue requirements f o r the spray dryer MgO FGD process are $28.8M (10.47 mills/kWh) i n mid-1984 dollars. The l e v e l i z e d annual revenue requirements f o r the spray dryer MgO process are $36.1M (13.13 m i l l s / k W h ) . The f i r s t - y e a r annual revenue requirements f o r the comparable limestone scrubbing process are $32.4M (11. 8 mills/kWh) i n mid1984 d o l l a r s . The l e v e l i z e d annual revenue requirements f o r the limestone scrubbing process are $45.2M (16.43 m i l l s / k W h ) . The f i r s t - y e a r annual revenue requirements f o r the c o n v e n t i o n a l MgO FGD process ( i n c l u d i n g p a r t i c u l a t e c o n t r o l ) a r e $40.4M (14.69 mills/kWh) i n mid-1984 d o l l a r s . L e v e l i z e d annual revenue requirements are $56. M (20.61 mills/kWh). These c o s t s a r e summarized i n T a b l e I I I . The c o m p l e t e d e t a i l s a r e presented i n Tables A-IV, A-V, and A-VI i n the Appendix. 7

7

TABLE I I I . ANNUAL REVENUE REQUIRMENTS SUMMARY First-year annual revenue requirements k$ mills/kWh

Conventional limestone process Spray dryer MgO process Conventional MgO process

Levelized annual revenue requirements k$ mills/kWh

32,400

11.78*

45,190

16.43*

28,800 40,400

10.47** 14.69**

36,113 56,683

13.13** 20.61**

*0nsite solids disposal **Byproduct ^ S O ^ c r e d i t $65.00/ton

Comparison The f i r s t - y e a r annual revenue requirements f o r the spray dryer MgO process a r e about 11% lower than those f o r the comparable limestone scrubbing process. T h i s economic advantage f o r the spray dryer MgO process i n c r e a s e s t o n e a r l y


FLUE


396

GAS

DESULFURIZATION

20% when the l e v e l i z e d a n n u a l revenue r e q u i r e m e n t s a r e compared. The primary reason f o r t h i s i n c r e a s e d advantage i n the l e v e l i z e d annual revenue requirements f o r the spray d r y e r MgO process i s the low f i r s t - y e a r o p e r a t i n g and maintenance cost. T h i s low f i r s t - y e a r o p e r a t i n g and maintenance cost i s due to the regenerable nature of the process. I t has a low raw materials c o s t and a high byproduct sales credit. The first-year and the l e v e l i z e d annual revenue requirements are lower f o r the spray dryer MgO process because of s i g n i f i c a n t d i f f e r e n c e s i n the byproduct c r e d i t , energy, and raw m a t e r i a l c o s t s . These annual c o s t savings more than o f f s e t the higher c a p i t a l charges f o r the spray dryer MgO process. The byproduct c r e d i t f o r s u l f u r i c a c i d i s the major reason f o r the lower spray dryer MgO annual revenue requirements. The credit o f $6.0M l o w e r s t h e f i r s t - y e a r a n n u a l revenue requirements by 40$. The gypsum produced i n the limestone scrubbing process i s assumed to be a waste m a t e r i a l to be l a n d f i l l e d and thus the limestone scrubbing process does not receive a comparable byproduct credit. Energy c o s t s are a l s o lower f o r the spray dryer MgO process. The higher e x i t temperature of the f l u e gas from the spray dryer coupled w i t h the c y c l i c reheat r e s u l t s i n a substantially l o w e r steam r e q u i r e m e n t . The electrical consumption i s 25% lower because of the s m a l l e r pumps needed f o r the S 0 a b s o r p t i o n area. The d i e s e l f u e l c o s t i s lower because of the s m a l l e r volume of m a t e r i a l disposed of i n the landfill. Raw m a t e r i a l c o s t s a r e l o w e r because o f t h e regenerable nature of the s p r a y d r y e r MgO process. There are only two revenue c o s t s which f a v o r the limestone scrubbing process, although they are not l a r g e enough to o f f s e t the cost advantages enjoyed by the spray dryer MgO process i n other areas. These advantages are the l a b o r cost and the l e v e l i z e d c a p i t a l charges and of these two, o n l y the l e v e l i z e d c a p i t a l charge d i f f e r e n c e i s o f any s i g n i f i c a n c e . The limestone scrubbing process has a $2.7M savings i n l e v e l i z e d c a p i t a l charges but t h i s i s o f f s e t by the $6.1M advantage i n f i r s t - y e a r o p e r a t i n g and maintenance c o s t s f o r the spray dryer MgO process. I n the comparison of the annual revenue requirements f o r the spray dryer MgO process w i t h those f o r the c o n v e n t i o n a l MgO process, i t i s apparent that both the f i r s t year and the l e v e l i z e d annual revenue requirements are 40? lower f o r the spray dryer MgO process ($28.8M v s . $40.4M f o r f i r s t y e a r ) . The most s i g n i f i c a n t d i f f e r e n c e between the processes i s the energy c o s t , i n p a r t i c u l a r , the f u e l o i l charges. The spray dryer MgO process uses expensive f u e l o i l only to operate the waste d i s p o s a l equipment w h i l e the c o n v e n t i o n a l MgO process uses f u e l o i l , not only f o r the waste d i s p o s a l equipment (which i s a r e l a t i v e l y minor amount) but a l s o to f i r e the c a l c i n e r and 2



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thus a l s o t o provide heat f o r the r o t a r y d r y e r s . The s l u r r y d r y i n g and c a l c i n i n g areas i n the c o n v e n t i o n a l MgO process r e q u i r e f u e l o i l a t a cost o f n e a r l y $8.6M. I n c o n t r a s t the spray dryer MgO process uses s t a t i o n c o a l a t a cost of $0.7M t o f i r e the c a l c i n e r . There i s a l s o a d i f f e r e n c e of $1M i n reheat energy costs between the processes i n f a v o r o f the spray dryer p r o c e s s because o f t h e h i g h e r s c r u b b e r o u t l e t f l u e g a s temperature and the cyclic reheat used. Electrical consumption, the other primary energy requirement, i s about 10$ h i g h e r i n the spray dryer process but t h e r e s u l t i n g c o s t d i f f e r e n c e o f $0.25M i s r e l a t i v e l y insignificant compared w i t h t h e o t h e r energy costs. The other major annual cost d i f f e r e n c e i s the l e v e l i z e d c a p i t a l charges. These l e v e l i z e d c a p i t a l c h a r g e s a r e c a l c u l a t e d as 14.7$ o f the c a p i t a l investment and because the spray dryer MgO process has a lower c a p i t a l investment, i t s l e v e l i z e d c a p i t a l charge i s approximately $1.4M l e s s than that f o r the c o n v e n t i o n a l MgO process. The b a s i s f o r t h i s l e v e l i z e d capital charge i s explained elsewhere ( 6 ) . The byproduct c r e d i t i s not s i g n i f i c a n t l y different between the MgO processes because the q u a n t i t y o f s u l f u r i c a c i d produced i s n e a r l y the same f o r both processes. A l l other annual c o s t s a r e approximately the same and do not have a s i g n i f i c a n t e f f e c t on the r e s u l t s . S e n s i t i v i t y Analysis Since the annual revenue requirements f o r the spray dryer and c o n v e n t i o n a l MgO processes appear t o be s e n s i t i v e t o the byproduct c r e d i t f o r s u l f u r i c a c i d , and s i n c e s u l f u r i c a c i d p r i c e s have r i s e n d r a m a t i c a l l y i n the l a s t few y e a r s , t h e s e n s i t i v i t y o f the f i r s t - y e a r annual revenue requirements t o the p r i c e o f byproduct s u l f u r i c a c i d was p r o j e c t e d . The r e s u l t s are shown i n F i g u r e 3. As i s apparent from t h i s f i g u r e the f i r s t - y e a r annual revenue requirements can vary somewhat, depending on the p r i c e r e c e i v e d from the byproduct s u l f u r i c a c i d . The base-case c r e d i t o f $65/ton o f 100$ H2SO4 r e s u l t s i n a f i r s t - y e a r annual revenue requirement o f 10.47 mills/kWh f o r the spray dryer MgO process and 14.69 mills/kWh f o r the c o n v e n t i o n a l MgO process. A t a byproduct c r e d i t o f $35/ton which i s approximately e q u i v a l e n t t o the p r i c e o f s u l f u r i c a c i d i n the p a s t ( o r w h i c h c o u l d be t h e 1984 p r i c e n e t t e d a f t e r t r a n s p o r t a t i o n c o s t s are s u b t r a c t e d f o r a u t i l i t y s i t u a t e d f a r from the u l t i m a t e consumer), t h e f i r s t - y e a r annual revenue requirements f o r the spray dryer MgO process r i s e n e a r l y 10 percent to 11.53 mills/kWh. T h i s c o s t , although s l i g h t l y lower than that f o r the limestone scrubbing process, i s e s s e n t i a l l y e q u i v a l e n t given the accuracy a s s o c i a t e d w i t h t h i s study. F o r


FLUE

398


I

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DESULFURIZATION

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s Conventional MgO Process

I co 15 k H Z

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Limestone Scrubbing Process

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I 76

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BYPRODUCT SULFURIC ACID PRICE, $/ton Figure 3.

Sensitivity of annual revenue requirements to byproduct sulfuric acid price.


18.

BURNETT AND WELLS


399

the o p t i m i s t i c $100/ton byproduct c r e d i t case, the f i r s t - y e a r annual revenue requirements decrease 13 percent t o 9.33 mills/kWh o r about 21 percent l e s s than the f i r s t - y e a r annual revenue requirements f o r the base-case limestone scrubbing process. F o r the c o n v e n t i o n a l MgO process the r e s u l t i n g f i r s t year annual revenue requirements are 13.63 mills/kWh o r about 18 percent higher than those f o r the limestone process. CONCLUSIONS AND SUMMARY


Conclusions The primary c o n c l u s i o n s o f t h i s conceptual design and study-grade economic e v a l u a t i o n are l i s t e d below: 1. The spray dryer MgO process appears t o have a s l i g h t advantage (about 10?) over a comparable limestone scrubbing process i n terms o f both f i r s t - y e a r and l e v e l i z e d annual revenue requirements. T h i s new MgO process, however, has a higher c a p i t a l investment than the limestone scrubbing process. 2. The spray dryer MgO process has an economic advantage over the c o n v e n t i o n a l MgO process i n terms of c a p i t a l investment (8?), first-year annual revenue requirements (40?), and l e v e l i z e d annual revenue requirements (40?). The primary d i f f e r e n c e f o r t h i s l a r g e cost advantage f o r the spray dryer MgO process i s due t o the lower energy consumption and the use o f inexpensive c o a l t o f i r e the c a l c i n e r r a t h e r than No. 2 fuel o i l . Summary Based on the r e s u l t s o f t h i s i n i t i a l study, the spray dryer MgO process appears t o be a promising new technology. However the design i s based on numerous t e c h n i c a l assumptions which may o r may not be a c c u r a t e . Therefore a s m a l l (~*1-MW e q u i v a l e n t ) p i l o t plant w i l l be necessary to t e s t t h i s new FGD process. TVA i s planning t o pursue funding f o r a study t o determine the cost o f such a p i l o t p l a n t which can confirm these assumptions and a s s i s t i n c r e a t i n g an economical and t e c h n i c a l l y v i a b l e process f o r c o n v e r t i n g p o l l u t a n t m a t e r i a l i n t o a u s e f u l byproduct. APPENDIX D e t a i l e d c a p i t a l and annual revenue requirement c o s t s f o r the three processes studied here are presented i n the f o l l o w i n g Tables A-I through A-VI.


400

FLUE

TABLE A - I .


CONVENTIONAL LIMESTONE PROCESS

SUMMARY OF CAPITAL INVESTMENT (500-MW new c o a l - f i r e d power u n i t , 3.5% s u l f u r i n c o a l ; 89.6% S 0 removal; o n s i t e s o l i d s d i s p o s a l ) 2


D i r e c t Investment

Investment, K$

M a t e r i a l handling Feed p r e p a r a t i o n P a r t i c u l a t e removal Gas handling S0 absorption Stack gas reheat Solids separation

2,518 4,618 9,998 13,653 20,342 3,325 3i350

2

T o t a l process

capital

Services, U t i l i t i e s ,

and Miscellaneous

T o t a l d i r e c t investment excluding l a n d f i l l S o l i d s d i s p o s a l equipment L a n d f i l l construction T o t a l d i r e c t investment

59,087 3«545 62,632 1,007 3.441 67,080

I n d i r e c t Investment Engineering design and s u p e r v i s i o n A r c h i t e c t and engineering c o n t r a c t o r Construction expense Contractor fees Contingency Landfill indirects T o t a l f i x e d investment

4,384 1»253 10,021 3,132 8,142 1«348 95,360

Other C a p i t a l Investment Allowance f o r s t a r t u p and m o d i f i c a t i o n s I n t e r e s t during c o n s t r u c t i o n Royalties Land Working c a p i t a l T o t a l c a p i t a l investment D o l l a r s of t o t a l c a p i t a l per kW of generation c a p a c i t y Basis:

TVA design and economic premises.


7,165 14,719 1.070 3.639 121,953 243.91

18.

BURNETT AND WELLS

TABLE A - I I .


401

SPRAY DRYER MgO PROCESS


SUMMARY OF CAPITAL INVESTMENT (500-MW new c o a l - f i r e d power u n i t , 3.5% s u l f u r i n c o a l ; 89.6% SO2 removal; o n s i t e s o l i d s d i s p o s a l ) Investment* K$ D i r e c t Investment 1,124 755 10,992 8,555 19,894 6,906 1,145 11,985 1,879 m

Material handling Feed preparation Gas h a n d l i n g F l y ash removal SO^ absorption Calcination Offgas cleanup Acid plant A c i d storage and shipping Ash purge

64,201

T o t a l process c a p i t a l

3.852

S e r v i c e s , U t i l i t i e s , and Miscellaneous T o t a l d i r e c t investment excluding

waste d i s p o s a l

68,053 467 1,595

S o l i d s d i s p o s a l equipment L a n d f i l l construction Pond c o n s t r u c t i o n

1.452 71,567

T o t a l d i r e c t investment

Continued on next page.


402

FLUE

TABLE A - I I .

(continued).


SPRAY DRYER MgO PROCESS


SUMMARY OF CAPITAL INVESTMENT

I n d i r e c t Investment Engineering design and s u p e r v i s i o n A r c h i t e c t and engineering c o n t r a c t o r Construction expense Contractor fees Contingency Waste D i s p o s a l I n d i r e c t Investment T o t a l f i x e d investment

4,636 1,234 10,635 2,767 15,928 SL25. 107,766

Other C a p i t a l Investment Allowance f o r s t a r t u p and m o d i f i c a t i o n s I n t e r e s t during c o n s t r u c t i o n Royalties Land Working c a p i t a l T o t a l c a p i t a l investment D o l l a r s of t o t a l c a p i t a l per kW of generation capacity Basis:



10,325 16,739 737 —3t93Q 139,497 278.99

18.

BURNETT AND WELLS


TABLE A - I I I .

403

CONVENTIONAL MgO PROCESS

SUMMARY OF CAPITAL INVESTMENT


(500-MW new c o a l - f i r e d power u n i t , 3.5% s u l f u r i n c o a l ; 89.6% SO2 removal; o n s i t e s o l i d s d i s p o s a l ) Investment. k$ D i r e c t Investment 1,278 405 10,983 9,998 8,664 3,877 8,206 1,578 7,525 3,167 10,051

M a t e r i a l handling Feed preparation Gas h a n d l i n g F l y ash removal SO2 absorption Stack gas reheat Chloride purge S l u r r y processing Drying Calcination Acid p l a n t A c i d storage and shipping

1.35? 67,090

T o t a l process c a p i t a l

4.025

S e r v i c e s , U t i l i t i e s , and Miscellaneous T o t a l d i r e c t investment excluding

waste d i s p o s a l

71,115 461 1,575

S o l i d s d i s p o s a l equipment L a n d f i l l construction Pond c o n s t r u c t i o n

3.02? 76,179

T o t a l d i r e c t investment

Continued on next page.


404

FLUE

TABLE A - I I I .

(continued).


CONVENTIONAL MgO PROCESS


SUMMARY OF CAPITAL INVESTMENT I n d i r e c t Investment Engineering design and s u p e r v i s i o n A r c h i t e c t and engineering c o n t r a c t o r Construction expense Contractor fees Contingency Waste D i s p o s a l I n d i r e c t s T o t a l f i x e d investment

4,871 1,316 11,166 3,023 16,785 1i426 114,766

Other C a p i t a l Investment Allowance f o r s t a r t u p and m o d i f i c a t i o n s I n t e r e s t during c o n s t r u c t i o n Royalties Land Working c a p i t a l T o t a l c a p i t a l investment D o l l a r s of t o t a l c a p i t a l per kW of generation c a p a c i t y Basis:



10,828 17,832 953 5*304 149,683 299.37

BURNETT AND WELLS


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Conceptual Design and Economics of an Improved Magnesium Oxide

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