Coal Liquefaction Fundamentals - American Chemical Society

3 The Characteristics of Australian Coals and Their Implications in Coal Liquefaction R. A. DURIE

Downloaded by CORNELL UNIV on August 9, 2016 | http://pubs.acs.org Publication Date: October 14, 1980 | doi: 10.1021/bk-1980-0139.ch003

R. W. Miller & Co., Pty. Ltd., 213 Miller Street, North Sydney, New South Wales, 2060

In Australia, coal represents, in energy terms, over 97% of the country's non-renewable fossil fuel based energy resources, yet indigenous o i l which barely representa 1% of these resources, together with imported oil, supply over 50% of the energy demand with much of this from the transport sector. This situation, catalyzed by the OPEC o i l embargo in 1973, has led to strong and sustained interest in the prospects for producing liquid fuels from the abundant coal resources. The reserves of recoverable fossil fuels (1) and the present pattern of energy demand in Australia (2) are shown in more detail in Tables 1 and 2, respectively. Location, Geology and General Characteristics of Australian Coals The geographical distribution of Australia's coal resources is shown in Fig. 1. New South Wales and Queensland possess large reserves of black coals in the Sydney and Bowen Basins, respectively, adjacent to the eastern seaboard. Significant deposits of bituminous coals are also known to occur in remote areas in South Australia at Lake Phillipson in the Arckaringa Basin and at currently inaccessible depth (200-300 m) in the Cooper Basin (3,4). [An estimated 3.6x106 million tonnes in the latter]. Large reserves of brown coals occur in Victoria with smaller deposits in New South Wales and South Australia. Whereas the majority of the black coals in the northern hemisphere, including the USA and Europe, were formed during the Carboniferous age, the black coals of Australia are, in the main, Permian. The latter include the coals from the two major basins the Sydney and the Bowen - and also large deposits in the Galilee Basin (Queensland), at Oaklands (N.S.W.), Lake Phillipson (South Australia) and Collie (West Australia) as well as the deep coal in the Cooper Basin (the Cooper Basin is in the N.E. corner of South Australia extending into the S.W. corner of Queensland (refer Fig. 1) ). 0-8412-0587-6/80/47-139-053$05.25/0 © 1980 American Chemical Society Whitehurst; Coal Liquefaction Fundamentals ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

54

C O A L LIQUEFACTION

Table I

A u s t r a l i a ' s F o s s i l F u e l Energy


Resources

Quantity (D emo ns t r a ted ) (10

Resource Black C o a l * In-Situ Recoverable

48.55xl0 t 27.22xl0 t

Brown Coal In-Situ Recoverable

40.93xl0 t 39.00xl0 t

Crude O i l and Condensate In-Situ Recoverable

49.00xl0 bbl 20.70xl0 bbl

N a t u r a l Gas + LPG In-Situ Recoverable

545xl0 327x10

9

9

9

9

9

9

9

3

m m

9

3

Total In-Situ Recoverable •Demonstrated estimated t o resources of representing resources. Table I I

FUNDAMENTALS

1 8

S p e c i f i c Energy Joules) (Percentage)

1390 780

75.5 65.8

400 380

21.7 32.1

29.7 12.4

1.6 1.0

21.0 12.6

1.2 1.1

1840.7 1185.0

100 100

+ Inferred i n - s i t u black coal resources are be 5 6 0 0 x 1 ο J with 55% r e c o v e r a b l e - i n f e r r e d crude o i l and n a t u r a l gas a r e r e l a t i v e l y minor o n l y 1% and 8%, r e s p e c t i v e l y , of the demonstrated 18

P a t t e r n o f A u s t r a l i a n Use o f F o s s i l F u e l s 1974-75 15

T o t a l primary energy demand 2 5 1 2 x 1 ο J c o n s i s t i n g o f : c o a l 1035x1ο J; o i l 1318x1ο J; n a t u r a l gas 1 5 9 x 1 ο J 15

15

15

% of Fuel Type

% T o t a l Primary Energy

Coal E l e c t r i c i t y generation Iron and s t e e l Other

61 25 14

26) 10 ) 42 6)

Oil Transport* Fuel o i l Other

61 15 24

32) 8 ) 52 12)

N a t u r a l Gas E l e c t r i c i t y generation Other

20 80

*Includes f u e l o i l f o r bunkering

Whitehurst; Coal Liquefaction Fundamentals ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

Whitehurst; Coal Liquefaction Fundamentals ACS Symposium Series; American Chemical Society: Washington, DC, 1980. Figure 1.

Australian coalfields (3)


I

Β

g

56

C O A L LIQUEFACTION

FUNDAMENTALS


These Permian c o a l s , together with counterparts i n India, South A f r i c a , A n t a r c t i c a and South America, a r e r e f e r r e d to as Gondwana c o a l s a f t e r the h y p o t h e t i c a l super-continent which subsequently broke up i n t o the c o n t i n e n t s and sub-continents mentioned above (5) . The c l i m a t i c c o n d i t i o n s p r e v a i l i n g i n the Permian d u r i n g the formation of these Gondwana c o a l s were d i f f e r e n t from those f o r the Carboniferous c o a l s of North America and Europe. As a r e s u l t of a c o o l e r c l i m a t e with a l t e r n a t i n g d r y and wet p e r i o d s , and o f the consequent d i f f e r e n c e i n the o r i g i n a l p l a n t m a t e r i a l s , the c o n d i t i o n s of accumulation, the slower r a t e of accumulation, and prolonged d u r a t i o n of s i n k i n g , the A u s t r a l i a n (and other Gondwana) Permian c o a l s d i f f e r i n many r e s p e c t s from the Carboniferous c o a l s of the northern hemisphere. Thus f o r the former c o a l s , seam t h i c k ness tends to be g r e a t e r , v i t r i n i t e content lower, s e m i - f u s i n i t e content higher, m i n e r a l matter content h i g h and sulphur content g e n e r a l l y low; the ash d e r i v e d from the m i n e r a l matter i s u s u a l l y r e f r a c t o r y with high f u s i o n temperatures. These c o a l s occur i n seams near the surface, and a t depth. The A u s t r a l i a n Permian c o a l s v a r y widely i n rank (maturity) and type ( v i t r i n i t e content) from the Oaklands (N.S.W.) c o a l a t 72% (dry a s h - f r e e basis) carbon, a hard brown c o a l (6), c o n t a i n i n g 17% v i t r i n i t e , a t one extreme - through high v o l a t i l e bituminous c o a l s such as G a l i l e e (Queensland) c o a l a t 77% carbon, 16% v i t r i n i t e ; B l a i r A t h o l (Queensland) c o a l a t 82% carbon, 28% v i t r i n i t e , L i d d e l l (N.S.W.) c o a l a t 82% carbon, and >70% v i t r i n i t e - t o low v o l a t i l e bituminous such as Peak Downs (Queensland) a t 89% carbon, 71% v i t r i n i t e , and B u l l i seam (N.S.W.) 89% carbon, 45% v i t r i n i t e . In a d d i t i o n to the Permian c o a l s there a r e occurrences of Mesozoic and T e r t i a r y c o a l s i n A u s t r a l i a . Mesozoic c o a l s occur i n small basins i n South A u s t r a l i a , Tasmania, New South Wales and Queensland and vary i n rank from brown to bituminous. Perhaps the most notable occurrences i n the present context a r e the Walloon c o a l s i n the Clarence-Morton b a s i n i n Queensland, e.g. M i l l m e r r a n bituminous c o a l (78% carbon, v i t r i n i t e p l u s e x i n i t e -90%). The most s i g n i f i c a n t T e r t i a r y c o a l s are represented by the v a s t brown c o a l d e p o s i t s i n V i c t o r i a , p a r t i c u l a r l y i n the Latrobe V a l l e y . These brown c o a l s w i t h 68-70% carbon, occur i n v e r y t h i c k seams (up t o 200 meters) under shallow cover (90% v i t r i n i t e ) from a h i g h v o l a t i l e bituminous c o a l ( L i d d e l l seam N.S.W., 83.6% carbon and 43% v o l a t i l e matter both expressed on a d r y a s h - f r e e b a s i s ) . However, i t i s e v i d e n t t h a t the c o n v e r s i o n of the 'whole c o a l i n c r e a s e s r a p i d l y w i t h i n c r e a s e i n hydrogen pressure (under otherwise s i m i l a r c o n d i t i o n s - batch autoclave, 4h. @ 400°C). T h i s c o u l d suggest e i t h e r t h a t c o n v e r s i o n o f the v i t r i n i t e i s suppressed by other components i n the c o a l , p a r t i c u l a r l y a t the lower pressures, or more l i k e l y , that other macérais are p a r t i c i p a t i n g to an i n c r e a s i n g extent as the hydrogen pressure i n c r e a s e s . 1

C o n s i d e r a t i o n of the l a t t e r r e s u l t s i n r e l a t i o n to those of Cudmore (10), d i s c u s s e d above, emphasize the need f o r c a u t i o n when g e n e r a l i s i n g on the i n f l u e n c e of c o a l c h a r a c t e r i s t i c s on conversion. Indeed, i t would appear t h a t the a b s o l u t e and r e l a t i v e


60

COAL LIQUEFACTION

FUNDAMENTALS


Vitrain

82

h3.4

6.9

10.3

13.8

17.2

20.6 Mpa

500

1000

1500

2000

2500

3000 psi

Initial hydrogen pressure

Figure 3. Effect of hydrogen pressure on conversion of Liddell coal: (O), un treated coal; (%) demineralized coal; (Α λ hand-picked vitrain. Reaction tempera ture = 400° C; reaction time = 4 hr.


3.

DURIE

Australian

Coals

61

c o n t r i b u t i o n of the v a r i o u s pétrographie components i s dependent on the process c o n d i t i o n s which i n c l u d e , i n t e r a l i a , the hydrogen potential.


The petrography of brown c o a l s d i f f e r s from that of b l a c k c o a l s and i s l e s s w e l l developed. However, evidence i s mounting t h a t brown c o a l s can v a r y s i g n i f i c a n t l y , even w i t h i n the same seam, and t h a t these v a r i a t i o n s may e f f e c t t h e i r c o n v e r s i o n behaviour. The V i c t o r i a n Brown Coal C o u n c i l has i n i t i a t e d s t u d i e s i n t h i s area (with advice from the German Democratic R e p u b l i c ) . The E f f e c t of Elemental Composition I t i s w e l l e s t a b l i s h e d t h a t f o r any c o a l the s o - c a l l e d r e a c t i v e macérais, v i t r i n i t e and e x i n i t e , are r i c h e r i n hydrogen than the i n e r t macérais. Therefore, s i n c e the c o n v e r s i o n of c o a l s to l i q u i d f u e l s i n v o l v e s the p r o d u c t i o n of lower molecular weight products having atomic hydrogen to carbon r a t i o s i n the range 1.7 to 2 compared w i t h

Coal Liquefaction Fundamentals - American Chemical Society

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