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Fuel Sciences Division, Alberta Research Council, Edmonton, Alberta, Canada T6G 2C2

To p r o v i d e l a b o r a t o r y s u p p o r t f o r t h e A l b e r t a R e s e a r c h C o u n c i l ' s underground c o a l g a s i f i c a t i o n f i e l d t e s t program ( 1 ) , and means f o r e x p l o r i n g n o v e l o p e r a t i n g p r o c e d u r e s b e f o r e t a k i n g them i n t o t h e f i e l d , a g a s i f i c a t i o n s i m u l a t o r has been d e v e l o p e d . T h i s f a c i l i t y has been d e s i g n e d t o r e p r o d u c e t h e c o n d i t i o n s o f a c o a l seam u n d e r g o i n g g a s i f i c a t i o n , but e l i m i n a t e s p e r i p h e r a l m a t t e r s ( e . g . , w a t e r i n c u r s i o n ) and c o n s e q u e n t l y a l l o w s d e t a i l e d s t u d y o f r e a c t i o n k i n e t i c s and r e l a t e d a s p e c t s ( e . g . , c a v i t y f o r m a t i o n , sweep e f f i c i e n c y and h e a t l o s s e s ) . In c o n t r a s t t o p r e v i o u s l a b o r a t o r y w o r k , w h i c h g e n e r a l l y c e n t e r e d on s m a l l c o a l b l o c k s o r f i x e d bed r e a c t o r s , and commonly s o u g h t t o d e f i n e l i m i t i n g c o n d i t i o n s w h i c h c o u l d be c o r r e l a t e d w i t h m a t h e m a t i c a l m o d e l s , t h e ARC s i m u l a t o r e m p l o y s a 1 χ 1 χ 2m ( 3 x 3 x 6') b l o c k w h i c h r e t a i n s most o f t h e e s s e n t i a l f e a t u r e s o f an u n d i s t u r b e d c o a l seam. 1

Simulator

1

Design

The g e n e r a l a r r a n g e m e n t o f t h e s i m u l a t o r a s s e m b l y i s shown i n F i g u r e 1 and i s c o m p r i s e d o f a f l o w c o n t r o l s y s t e m , a r e a c t o r , a d a t a a c q u i s i t i o n s y s t e m and o v e r - r i d e c o n t r o l s t h a t e n s u r e safety in operations. The f l o w c o n t r o l s y s t e m p r o v i d e s f a c i l i t i e s f o r i n j e c t i n g a i r , s t e a m , o x y g e n o r o t h e r f l u i d s i n t o t h e r e a c t o r , and i s g o v e r n e d by d/p c e l l t r a n s m i t t e r s and p n e u m a t i c a l l y - a c t i v a t e d v a l v e s w h i c h p e r m i t a u t o m a t i c o r manual r e g u l a t i o n o f f l o w r a t e s and p r e s s u r e s . A l l r e a g e n t f l u i d s a r e f i r s t mixed a t p r e d e t e r m i n e d p r e s s u r e and t e m p e r a t u r e i n a m i x i n g t a n k b e f o r e t h e y a r e s e n t t h r o u g h an i n l e t gas c o n t r o l v a l v e i n t o an a u x i l i a r y p r e h e a t e r and t h e reactor. The l a t t e r i s a r e f r a c t o r y - 1 i n e d , r e c t a n g u l a r s h e e t m e t a l v e s s e l ; and a f t e r a c o a l b l o c k has been c l o s e l y f i t t e d i n t o t h e r e a c t o r , one o r more 3/V - 2" d i a m e t e r h o r i z o n t a l h o l e s , w h i c h s e r v e as i n i t i a l r e a c t i o n c h a n n e l s , and a p p r o p r i a t e l y p l a c e d v e r t i c a l i n j e c t i o n and p r o d u c t i o n h o l e s a r e d r i l l e d i n t o i t . An e l e c t r i c h e a t e r e l e m e n t , i n s e r t e d t o t h e b o t t o m o f t h e 1

This chapter not subject to U.S. Copyright. Published 1979 American Chemical Society.

Tomlinson et al.; Chemistry for Energy ACS Symposium Series; American Chemical Society: Washington, DC, 1979.


2

STEAM ·

co -

°2

AIR

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REACTOR I. UCG simulator-simplified

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CALORIMETER

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CHEMISTRY FOR ENERGY

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i n j e c t i o n h o l e , i s used t o i g n i t e t h e c o a l , and s u b s e q u e n t g a s i f i c a t i o n t h e n s i m u l a t e s u n d e r g r o u n d g a s i f i c a t i o n by t h e s o - c a l l e d s t r e a m method. S p a c e s between t h e c o a l b l o c k and t h e r e a c t o r w a l l s a r e f i l l e d w i t h r e f r a c t o r y cement t o p r e v e n t a c c u m u l a t i o n o f com b u s t i b l e g a s e s , and l e a k s a r e e x h a u s t e d f r o m t h e o u t e r c a s i n g . T e m p e r a t u r e s a r e measured w i t h 1/8" Type Κ SS s h e a t h e d t h e r m o c o u p l e s , w h i c h a r e cemented i n t o t h e b l o c k a t p r e d e t e r m i n e d locations. P r o d u c t gas i s c o o l e d , f r e e d o f p a r t i c u l a t e m a t t e r by p a s s a g e t h r o u g h a f i l t e r , and t h e n s e n t t h r o u g h a h e a t e x c h a n g e r w h e r e w a t e r and t a r s a r e c o n d e n s e d . F l o w r a t e s a r e m e t e r e d as t h e c l e a n e d gas l e a v e s t h e h e a t e x c h a n g e r . Gas c o m p o s i t i o n s a r e d e t e r m i n e d w i t h two p r o g r a m m a b l e g a s - c h r o m a t o g r a p h s and a g a s p a r t i t i o n e r ( w h i c h s e r v e s as backup u n i t f o r h y d r o g e n d e t e r m i n a t i o n s ) , and h e a t v a l u e s a r e c o n t i n u o u s l y m o n i t o r e d w i t h a m o d i f i e d gas c a l o r i m e t e r . A l l i n s t r u m e n t a t i o n f o r gas a n a l y s i s is c a l i b r a t e d w i t h c e r t i f i e d c y l i n d e r gases. The d a t a a c q u i s i t i o n n e t w o r k i s s c h e m a t i c a l l y shown i n F i g u r e 2 and makes use o f two c o m p u t e r p r o g r a m s . One - 'Therm - a c q u i r e s t e m p e r a t u r e - d a t a f r o m t h e r m o c o u p l e s v i a an A u t o d a t a 8 s c a n n e r , s t o r e s t h e s e d a t a , and d i s p l a y s them g r a p h i c a l l y on a l i n e p r i n t e r f o r e v e r y f i f t h sample group (see F i g u r e 7 ) . The s e c o n d p r o g r a m - ' B a l a n c e ' - f i r s t p r o m p t s and a c q u i r e s b a s i c d a t a r e l a t i n g t o t h e p r o g r e s s o f g a s i f i c a t i o n and t o p r o d u c t gas c o m p o s i t i o n s , and t h e n r e q u e s t s f r o m t h e c o n t r o l t e r m i n a l i n f o r m a t i o n a b o u t a number o f o t h e r p a r a m e t e r s ( e . g . , f l o w r a t e s ) w h i c h i t p r i n t s o u t as a r e p o r t on mass-, h e a t - and e n e r g y balances. A l l d a t a a r e s t o r e d i n d i s c f i l e s from which they can be r e t r i e v e d f o r f u r t h e r p r o c e s s i n g a f t e r c o m p l e t i o n o f a t e s t run. The s a f e t y s y s t e m was d e s i g n e d w i t h r e g a r d f o r t h e p a r t i c u l a r l a b o r a t o r y s p a c e and t h e b u i l d i n g as a w h o l e . 1

Experimental The p r o g r e s s o f g a s i f i c a t i o n i n a p r e v i o u s l y d r i l l e d r e a c t i o n c h a n n e l i s s c h e m a t i c a l l y i l l u s t r a t e d i n F i g u r e 3. T h i s shows t h e p r i n c i p a l r e a c t i o n z o n e s and i n d i c a t e s p y r o l y s i s i m m e d i a t e l y ahead o f g a s i f i c a t i o n ; and s i n c e t h e n a t u r e o f p y r o l y s i s p r o d u c t s is s t r o n g l y temperature-dependent ( 2 , 3 ) » the advance o f each r e a c t i o n z o n e t o any p o i n t i n t i m e c a n be q u i t e c l o s e l y d e t e r m i n e d by c o r r e l a t i n g t e m p e r a t u r e p r o f i l e s i n t h e c o a l w i t h t h e c h e m i c a l c o m p o s i t i o n o f t h e r e a c t i o n s p r o d u c t s . From s t u d i e s o f c o a l com b u s t i o n , i t i s e s t i m a t e d t h a t 90 p e r c e n t o f t h e t o t a l b u r n i n g t i m e of a p a r t i c l e r e l a t e s t o b u r n i n g of the d e v o l a t i 1 i z e d (char) p a r t i c l e (h). However, i n u n d e r g r o u n d g a s i f i c a t i o n , where a l a r g e e x c e s s o f c o a l e x i s t s , t h e r a t e o f c o a l c o n s u m p t i o n may be e x p e c t e d t o be z e r o o r d e r and i s , i n f a c t , f o u n d e x p e r i m e n t a l l y t o be i n d e p e n d e n t o f a i r f l o w r a t e s , but s t r o n g l y d e p e n d e n t on tern-


7.

GREENFELD

In-Situ

T . I.

FLOW

Coal

SILENT

700

CONTROL

DATA

TERMINAL

PHONE

Gasification

83

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TEKTRONIX 4662 PLOTTER

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DATA STORAGE CART D I S C R K 0 5 2.4 MEGA B Y T E S

AUTODATA 8 2 0 0 CHANNEL THERMOCOUPLE SCANNER

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GAS

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2.

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IMMEDIATE TEMP. PROFILES

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network


84



7.

GREENFELD

In-Situ

Coal

85

Gasification

p e r a t u r e - w i t h t h e o v e r a l l b u r n i n g r a t e c o n t r o l l e d by h e a t t r a n s fer. G e n e r a l l y , h e a t i s g e n e r a t e d by c o m b u s t i o n , w h i l e h e a t s i n k s a r e p r o v i d e d by e n d o t h e r m i c c h e m i c a l r e a c t i o n s , d e v o l a t i 1 i z a t i o n , e v a p o r a t i o n o f w a t e r and h e a t l o s s e s t h r o u g h c o n d u c t i o n , c o n v e c t i o n and r a d i a t i o n . To d a t e , f o u r g a s i f i c a t i o n r u n s , u s i n g two b l o c k s , have been conducted i n t h e s i m u l a t o r . The f i r s t r u n , p r i m a r i l y i n t e n d e d t o t e s t s y s t e m components and o p e r a t i n g p r o c e d u r e s , l a s t e d f o r a b o u t 22 h o u r s ( d u r i n g w h i c h a i r was i n j e c t e d a t 13-25 m / h r ( 8 - 1 5 s c f / mi η ) , and was t e r m i n a t e d when o x y g e n c o n c e n t r a t i o n s i n t h e p r o d u c t gas e x c e e d e d 5 p e r c e n t and t h e t e m p e r a t u r e began t o f a l l . Table I shows t h e c o m p o s i t i o n o f t h e o r i g i n a l c o a l , and T a b l e 11 summar i z e s t h e t e s t d a t a , which were assembled from t h e c o m p o s i t i o n o f t h e p r o d u c t gas on t h e a s s u m p t i o n t h a t p y r o l y s i s p r o d u c t s made no s i g n i f i c a n t c o n t r i b u t i o n t o i t . The c o n t r a r y a s s u m p t i o n , i . e . t h a t a l l gas was p r o d u c e d by t h e r m a l d e c o m p o s i t i o n o f t h e c o a l ( h e a t e d t o 300°C a t 3°C/min) w o u l d i n d i c a t e a y i e l d o f o n l y 13 s c f d r y g a s / l b c o a l (0.81 m /kg) and an e n e r g y r e c o v e r y o f M 2 percent. 3

3

TABLE I I FIRST BURN AVERAGE DATA Dry Coal Effected

Gas P r o - Heat duct ion Value

S c f D r y Gas

Btu

D r y Gas

SCFM

SCFM

SCF

LBS/HR

L b . Dry C o a l

Btu

Dry C o a l

12

100

15

70

BTU/

10

Material Recovery

Energy Recovery

Injection Rate

65±10%

For t h e p u r p o s e o f e s t i m a t i n g t h e e n e r g y r e c o v e r y and sweep e f f i c i e n c y , t h e c o a l b l o c k was c u t open a f t e r c o m p l e t i o n o f t h e t e s t , and t h e b u r n i n g p a t t e r n i n s p e c t e d . As shown i n F i g u r e h, the i n i t i a l c r o s s - s e c t i o n o f t h e r e a c t i o n c h a n n e l was f o u n d t o have been e n l a r g e d t o an e l l i p t i c a l s h a p e ( w i t h t h e m a j o r a x i s p e r p e n d i c u l a r t o t h e c h a n n e l ) , and t h e c a v i t y n a r r o w e d s t e a d i l y toward t h e p r o d u c t i o n h o l e . R e v e r s a l o f t h e gas f l o w would p r o b a b l y have a l l o w e d c o n t i n u a t i o n o f g a s i f i c a t i o n by m a k i n g f o r g r e a t e r sweep e f f i c i e n c y and t h u s c o m p e n s a t i n g t h e unsymmetrîcal burn c a v i t y . In t h e l i g h t o f t h e s e f i n d i n g s , a n o t h e r b l o c k was p r e p a r e d f o r more e x t e n s i v e t e m p e r a t u r e m e a s u r e m e n t s , and d i v i d e d l e n g t h w i s e i n t o two c o m p a r t m e n t s . s e c o n d g a s i f i c a t i o n t e s t was c a r r i e d o u t on t h e l e f t h a l f of t h e t e s t b l o c k , w i t h t h e h o r i z o n t a l channel choked o f f near t h e p r o d u c t i o n h o l e i n o r d e r t o s i m u l a t e b l o c k a g e w h i c h may o c c u r during i n - s i t u processing. A t t e m p t s t o 'push' t h e b u r n t h r o u g h the channel proved u n s u c c e s s f u l and, i n s t e a d , as s u s p e c t e d from



86

TABLE !. COAL BLOCK ANALYSES Capaci t y Moi s t u r e

BASIS

Dry

Dry Ash-Free

PROXIMATE COMPOSITION Moisture % Ash % V o l a t i l e Matter % F i x e d Carbon %

23.6 4.8 29.9 41.7

ULTIMATE COMPOSITION Carbon % Hydrogen % Sulfur % Ash * Moisture %

53.6 3.5 0.3 4.8 23.6

70.2 4.6 0.4 6.3

74.9 4.9 0.4

9,200

12,050

12,860

C a l o r i f i c Value, BTU p e r l b

6.3 39.2 54.5

41.8 58.2

gross

Figure 4.

First burn cavity

formation


7.

GREENFELD

In-Situ

Coal

Gasification

87

t h e t e m p e r a t u r e p r o f i l e s and l a t e r c o n f i r m e d when t h e b l o c k was opened f o r i n s p e c t i o n , an ' e a s i e r ' p a t h d e v e l o p e d t o t h e l e f t . T h i s e v e n t u a l l y c r e a t e d a c a v i t y i n t h e s h a p e and s i z e o f a l a r g e f o o t b a l l , from which a h o r i z o n t a l c r a c k extended over h a l f t h e l e n g t h o f t h e b l o c k . A l s o , v e r y p r o m i n e n t was a v e r t i c a l c r a c k a b o v e t h e o r i g i n a l c h a n n e l . Due t o p r e s s u r e l i m i t a t i o n s , a i r f l o w r a t e s were l i m i t e d t o 6 s c f / m i n i n j e c t e d a t 5 p s i g . Typical p r o d u c t gas c o m p o s i t i o n s a r e g i v e n i n T a b l e I I I . The maximum t e m p e r a t u r e was 1060°C, and p r o d u c t g a s e x i t e d a t a b o u t 100°C. TABLE I I I BURN No. 2 TYPICAL PRODUCT GAS

C0

CO

2

7.3 12.2 Π.7

H

2

10.5 9Λ 11.8

6.1»

6.3 7Λ

CH

CriHm

0 +Ar

N

2.1»

0.5

2.2 2.9

0.1»

13.1 7.3 7.8

59.8 62.2 57.9

4

2

0.5

2

Heat V a l u e BTU/SCF 88.1» 80.1 100.1»

A f t e r t a k i n g s u i t a b l e c o a l samples f o r a n a l y s i s , removing t h e b l o c k a g e and f i l l i n g t h e c a v i t y w i t h r e f r a c t o r y c e m e n t , t h e t h i r d b u r n t e s t was c a r r i e d o u t on t h e same c h a n n e l . F i g u r e 5 shows time-data p l o t s f o r t h i s burn. B e c a u s e much o f t h e m o i s t u r e had been d r i v e n f o r w a r d by t h e p r e c e d i n g b u r n , o n l y a r e l a t i v e l y l o w BTU p r o d u c t gas was p r o d u c e d ; b u t by c y c l i c a l i n j e c t i o n o f s t e a m and a i r , h e a t v a l u e s c o u l d be p e r i o d i c a l l y i n c r e a s e d . The e x p e r i m e n t was t e r m i n a t e d when t h e t e m p e r a t u r e i n t h e a d j a c e n t c o a l b l o c k began t o e x c e e d 200°C. K i n e t i c d a t a f o r t h e t h i r d e x p e r i m e n t have n o t y e t been a n a l y z e d , b u t i t a p p e a r s t h a t p r o d u c t gas h e a t v a l u e s depend m o s t l y on h y d r o g e n c o n t e n t s , and t h a t t h e u s e o f h i g h s t e a m / a i r r a t i o s p r o m o t e s h y d r o g e n f o r m a t i o n v i a C + H 0 ·> CO + H , f o l l o w e d by CO + H 0 -> C 0 + H . S m a l l i n c r e a s e s i n CH c o n t e n t a r e a l s o i n d i c a t e d under s u c h c o n d i t i o n s . As c a n be o b s e r v e d f r o m t h e t e m p e r a t u r e p l o t s shown i n F i g u r e 6, r a p i d c o o l i n g o f t h e s y s t e m r e q u i r e s f u r t h e r i n j e c t i o n o f a i r o r o x y g e n i n o r d e r t o m a i n t a i n r e a s o n a b l y h i g h gas h e a t v a l u e s and m i n i m i z e f l u c t u a t i o n i n h e a t v a l u e . The t e m p e r a t u r e p l o t s p r e s e n t e d h e r e a r e o n l y a s m a l l p o r t i o n o f t h e data c o l l e c t e d f o r heat d i s t r i b u t i o n c a l c u l a t i o n s . G e n e r a l l y , t h e h e a t i n g r a t e i s s l o w up t o 100°C (due t o w a t e r v a p o u r i z a t i o n ) a n d t h e r e a f t e r becomes f a s t e r , o n a v e r a g e a p p r o a c h i n g 0.5°C/min, and t h e c o m b u s t i o n t e m p e r a t u r e u s u a l l y e x c e e d s 1200°C. T h e r m o c o u p l e l o c a t i o n s a t w h i c h t e m p e r a t u r e s w e r e measured a r e i d e n t i f i e d i n F i g u r e 7. The f o u r t h b u r n was c a r r i e d o u t on t h e r i g h t h a l f o f t h e b l o c k , w i t h a i r a s w e l l a s some C 0 b e i n g i n j e c t e d f o r a b o u t 13 h o u r s . The d i a m e t e r o f t h e r e a c t i o n 2

2

2

2

2

k

2



a Sumw4

A

Sumw5

Β

Sumw6

C

300 .0

225 0

150 0

75 0

0 0 g 0. 0 Accumulated

QIx60

ή

Coal Consumed Clbs}

QP*x60

vs

1081 .0 Time Cm 1ns)

b

Β

1800 0

1 1350 0

Λ/Λλ

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450. 0

0 0 0. 0

1081 .0 SCF/H

Figure

5.

vs

Time Cmlns>

Computer plots of experimental parameter, burn No. 3. (a) Coal con sumption and (b) input and output gas flow rates.


In-Situ

GREENFELD

N2 — A 80.0

Coal

C02 — Β

Gasification

02

—6-

r

60.0

40.0

20.0

0.0 0.0

1081.0 %VoIume

Figure

5.

Computer

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Time Cm i ns)

of experimental parameter, Product gas composition.

burn

No. 3. (c and d)



THERM024

A

THERM028 — Β

0.0

THERMO14 — Θ -

1120.0 Temperature C°CO vs

E l a p s e d Time Cmlns>

Figure 6. Computer plots of temperature data. (Top) Channel A, longitudinal temperature distribution: (a) ignition point; (b) Γ from ignition point; (c) 2' from ignition point. (Top right) Section G, radial temperature distribution. (Bottom right) Fluid flow: (a) inlet fluids; (b) product gas;(c)product gas off heat exchanger.


GREENFELD

In-Situ

THERMO 3 — A

Coal

Gasification

THERM027 — Β

THERMO40

—

THERM051 — B

THERM053

e-

1100.0 r

825.0 f-

550.0 f*

275.0 f-

0.0 i = 0.0

THERMO50

A

800.0 r

0-0 Temperature C°C> vs

1120.0 E l a p s e d Time Cm Ins)



«22 653.

«26 71.

48.7

Location

Figure

7.

«28 907.

«31 57. «33 558.

«32 234.

57.6 b

OUT- 18.7

(longitudi

76.5

OUT- 586.S

COAL SURFACE-

IN-140.0

TIME 04111

Burn No. 3

23.9

GAS FLOUS

during

RELIEF LINE-

and temperature distribution nal sections)

«34 166.

of thermocouples

«30 91.

OUTER CASING*

IN-284.0

THERMOCOUPLE TEMPERATURES HEAT EXCHANGE *

C- 278.1

*25 « 2 7 *29 762. 801. 911.

Β-

OUTPUT-11.20

«24 838.

«23 83.

INPUT-8.00

«20 *21 389. 648.

«36 62.

MATER J

CO to

7.

GREENFELD

93

In-Situ Coal Gasification

TABLE IV PHENOLS IN TAR CO-PRODUCED BY GASIFICATION, BURN NO. 4 Sample

Number

1(1lpm) Ammonia, g / l i t r e Phenol, g / l i t r e (absorption data) Phenol s, g / 1 i t r e ( i d e n t i f i e d by G.C.) Ether-soluble organics g/1i t r e

2(1:55am)

3(4:30am)

2.8

3.8

3.2

4.28

6.95

6.51

3.00

5.10

4.40

13.30

4.13

7.53

6.42

126.88

Weight percent d i s t r i b u t i o n o f phenols Phenol 0-Cresol m-Cresol p-Cresol 0-Ethylphenol m-Ethylphenol p-Ethylphenol 2,6-dimethylphenol 2,4-and 2,5d imethyl phenol 2 . 3 - and 3 , 5 d i m e t h y l phenol 3 . 4 - d imethy1 p h e n o l T r i methy 1 p h e n o l s

Condensate 6.9

identified

52.0 9.4 15.8 12.9 1.3 1.1 1.0 0.2

50.0 10.0 16.5 12.2 1.7 1.4 1.3 0.3

47.7 10.2 17.3 12.4 1.7 1.5 1 .4 0.5

32.9 8.4 14.7 11.8 1.8 3.0 5.0 1.4

2.9

3.1

3.4

9.2

2.4 0.9

2.4 1.1

2.6 1.1

7.7 4.2

-

?

?


CHEMISTRY

94

FOR ENERGY

c h a n n e l was 2" f o r t h e f i r s t o n e - f o o t l e n g t h , a n d 7/8" o v e r t h e remaining four f e e t . The b u r n was t e r m i n a t e d when t h e f i r e b r o k e through t h e f r o n t r e a c t i o n w a l l . Steam e x t i n g u i s h e d t h i s f i r e q u i t e e f f e c t i v e l y a n d p r o d u c e d a medium-BTU gas ( w i t h 335 B T U / s c f ) . I t was a l s o f o u n d t h a t t h e c a v i t y s h i f t e d t o w a r d t h e l e f t w a l l , p r o b a b l y due t o t h e f a c t t h a t p r e v i o u s h e a t i n g on t h a t s i d e somewhat i n c r e a s e d t h e p e r m e a b i l i t y o f t h e c o a l . The o v e r a l 1 c a v i t y g e o m e t r y and c h a n n e l l e n g t h w e r e s i m i l a r t o t h o s e f o u n d i n t h e t h i r d t e s t , and b u r n i n g r a t e s w e r e a l s o s i m i lar. Over most o f t h e burn p e r i o d (11 h r s ) s t a b l e c o n d i t i o n s p r e v a i l e d , and a g a s w i t h o v e r 110 B T U / s c f was p r o d u c e d ( C 0 - 1 1 . 3 % , CO-15.4%, H - 1 3 . 3 * , C h V 1 . 6 ! , C H - 0 . 3 % , 0 + A r - 1 . 2 % , N - 5 6 . 9 * ) . The a i r : p r o d u c t g a s r a t i o was MD.73, and e n e r g y r e c o v e r y r e a c h e d a b o u t 70 p e r c e n t ( o r j u s t o v e r 80 p e r c e n t i f t h e s e n s i b l e h e a t o f t h e g a s i s i n c l u d e d ) . The h e a t v a l u e s r e c o r d e d by t h e c a l o r i m e t e r a r e a b o u t 8 p e r c e n t h i g h e r t h a n t h o s e computed f r o m g a s c o m p o s i t i o n s a n d s h o w i n g p e a k s n o t d e t e c t e d by t h e gas c h r o m a t o g r a p h . T a b l e IV shows t h e a n a l y s i s o f t h e ( t a r ) c o n d e n s a t e w h i c h was r e c o v e r e d f r o m t h e raw p r o d u c t g a s a t a r a t e o f 2 £/hr. 2

2

n

m

2

2

Conclus ion The i n - s i t u c o a l g a s i f i c a t i o n s i m u l a t o r a p p e a r s t o behave much l i k e a n u n d e r g r o u n d c o a l seam u n d e r g o i n g g a s i f i c a t i o n , and y i e l d s t y p i c a l gas a t r a t e s and e f f i c i e n c i e s v e r y s i m i l a r t o those observed i n f i e l d t e s t s . A t t i m e s , i t e v e n posed s i m i l a r c o n t r o l p r o b l e m s , s u c h a s l o c a t i n g t h e c o m b u s t i o n f a c e , g a s l e a k a g e and self re-ignition. The e x t e n s i v e t e m p e r a t u r e d a t a w h i c h s t i l l r e m a i n t o be c o r r e l a t e d w i t h c h a r r e s i d u e s , t h e shape o f t h e burn c a v i t y , and c h e m i c a l a n a l y s e s , when combined w i t h d a t a f r o m s e p a r a t e c a r b o n i z a t i o n t e s t s now i n p r o g r e s s , a r e e x p e c t e d t o p r o v i d e i n f o r m a t i o n f r o m w h i c h t h e e x t e n t o f g a s i f i c a t i o n a n d t h e sweep e f f i c i e n c y can be p r e d i c t e d w i t h r e a s o n a b l e a c c u r a c y . Much e x p e r i e n c e has a l s o been g a i n e d w h i c h s h o u l d c o n t r i b u t e toward b e t t e r u n d e r s t a n d i n g o f t h e parameters t h a t c o n t r o l e f f e c tive gasification. Based o n t h i s e x p e r i e n c e , an i m p r o v e d r e a c t o r , c a p a b l e o f o p e r a t i n g a t h i g h e r p r e s s u r e s , and a l l o w i n g s a m p l i n g a l o n g t h e r e a c t i o n c h a n n e l a s w e l l a s f l o w r e v e r s a l , i s now b e i n g d e s i g n e d , and t e s t s s i m u l a t i n g o p e r a t i o n o f a l o n g w a l 1 g e n e r a t o r a r e p l a n n e d . F u t u r e work w i l l a l s o i n c l u d e t e s t s o f h o l e - l i n k i n g t e c h n i q u e s and s t u d i e s o f t h e r e l a t i o n between c a v i t y f o r m a t i o n and t h e o r i e n t a tion of cleat i n the coal. Acknowledgements I am i n d e b t e d t o D. Swenson and H. W a s y l y k f o r t e c h n i c a l a s s i s t a n c e i n t h e e x p e r i m e n t a l w o r k , t o D r . R.A.S. Brown f o r v a l u a b l e a d v i c e r e l a t i n g t o t h e d e s i g n and o p e r a t i o n o f t h e


7.

GREENFELD

In-Situ

Coal

Gasification

95

s i m u l a t o r f a c i l i t y , and t o D r . N. B e r k o w i t z f o r h e l p f u l d i s c u s s i o n s and a s s i s t a n c e i n t h e p r e p a r a t i o n o f t h i s p a p e r .

Abstract In actual i n - s i t u coal gasification, numerous processes, i . e . oxidation, reduction, thermal cracking and a variety of c a t a l y t i c as well as non-catalytic reactions, occur in overlapping zones, and to explore the chemistry of these reactions as single or consecutive unit processes is v i r t u a l l y impossible. It i s , however, feasible to study the individual reactions under controlled conditions by simulating i n - s i t u gasification in the laboratory. This paper describes a simulator which has been developed at the Alberta Research Council and permits gasification in a two-ton coal block. I n i t i a l gasification experiments with air, steam and carbon dioxide are summarized, and data for product gas composition, heat propagation through the coal block, and gasification rates as functions of the geometry of the reaction channel are presented. Literature Cited

1.

2. 3. 4.

Berkowitz, N. and Brown, R.A.S., " I n - S i t u Coal G a s i f i c a t i o n : The Forestburg (Alberta) F i e l d T e s t " , The Canadian Mining and M e t a l l u r g i c a l Bulletin (December 1977). F i t z g e r a l d , D . , 8th Arthur Duckham F e l l o w s h i p Report, I n s t . Gas. Engrs. (London) (1957), P u b l . No. 516. F i t z g e r a l d , D. and van Krevelen, D.W., Fuel (1959), 17. Essenhigh, R . H . , "Dominant Mechanisms in the Combustion o f C o a l " , ASME P u b l . (1971).

RECEIVED September 2 5 , 1978.


Chemistry for Energy - American Chemical Society

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