Author

CHUN YEN LIN

Date of Graduation

1977

Document Type

Dissertation/Thesis

Abstract

T h is s tu d y exam ines th e a v a ila b le work en e rg y f o r c o a l c o n v e rsio n p ro c e s s e s as d e r iv e d from th e second law o f therm odynam ics. The conc e p t o f a v a ila b le work en e rg y can p ro v id e th e r e la t io n s h i p betw een o p e r a tin g c o n d itio n s and u s e f u l en e rg y re c o v e r y ; w h ile th e t o t a l en e rg y b a se d on th e f i r s t law o f therm odynam ics can e s t a b l i s h th e r e la t io n s h i p betw een q u a n t i t i e s o f h e a t and work en e rg y . The c o n c ep t o f t o t a l en e rg y re c o v e ry and th e a v a ila b le work en e rg y lo s s i s a p p lie d to each o f th e p ro c e s s u n its in v a r io u s co a l c o n v e rsio n p ro c e s s e s . The c o a l c o n v e rsio n p ro c e s s e s w hich w ere s tu d ie d in c lu d e th o s e w hich p ro d u c e s y n t h e t i c cru d e o i l , p i p e l i n e g a s, m ethanol a n d /o r e l e c t r i c i t y . The p r e lim in a r y c o n c e p tu a l d e sig n o f th e co a l c o n v e rsio n p ro c e s s e s i s i n v e s tig a te d in o r d e r to e s tim a te th e u n it p ro d u c tio n c o s t o f th e v a r io u s p ro d u c ts . Some d is c u s s io n s o f a l t e r i n g th e o p e r a tin g c o n d itio n s in o r d e r to in c r e a s e th e a v a ila b le work en e rg y re c o v e ry a r e p r e s e n te d in t h i s s tu d y . About 15% o f a v a ila b le work en e rg y in th e fe e d c o a l i s l o s t in th e c o a l p y r o ly s is s te p , and 12% i s l o s t in th e COED c h a r g a s i f i ­ c a tio n . Oxygen consum ption in th e COED p y r o ly s is r e p r e s e n ts about 1% lo s s in th e a v a ila b le work en e rg y a s s o c ia te d w ith th e fe e d c o a l. A 5% in c r e a s e in carbon u t i l i z a t i o n am ounts to a re d u c tio n o f a p p ro ­ x im a te ly 4% o f th e a v a ila b le work en e rg y lo s s in th e g a s i f i c a t i o n p ro c e s s b a se d on th e a v a ila b le work en e rg y o f th e fe ed c o a l. The seco n d law e f f ic ie n c y o f th e com bustion p ro c e s s s tu d ie d h e r e w i l l i n ­ c re a s e 3% i f th e com bustion te m p e ra tu re i s in c re a s e d from 2000°F (1367 K) to 2600°F (1700 K ). In th e steam tu r b in e pow er g e n e ra tio n p r o c e s s , th e steam b o i l e r h as th e most a v a ila b le work en e rg y lo s s . Use th e re h e a t p ro c e s s w ith 2400 p s ia /1 0 0 0 °F /1 0 0 0 °F [1 6 .5 (MN/m2) / 811 K/811 K] has th e second law e f f i c i e n c y o f 47%, w h ile th e p ro c e s s w ith 600 p sia /1 0 0 0 ° F [4 .1 (MN/m2)/8 1 1 K] h as th e second law e f f ic ie n c y o f 40%. In th e p ro d u c tio n o f s y n th e tic c ru d e o i l and m e th a n o l, th e second law e f f ic ie n c y o f th e o v e r a ll p ro c e s s i s 57%, w h ile t h a t f o r th e s y n t h e t i c crude o i l and p i p e l i n e gas p ro d u c tio n i s 53%. Low-Btu gas p r o d u c tio n has th e second law e f f i c i e n c y o f 6 8 %. A ll th e s e c o a l c o n v e rsio n p ro c e s s e s a re d e s ig n a te d on a s e l f e n e r g y - s u s ta in ­ in g b a s i s . Thus, i t h as been found t h a t p ro c e s s a n a ly s is b ase d upon c o n s id e r a tio n s d e r iv e d from th e second law o f therm odynam ics can be u sed to a c h ie v e an u n d e rs ta n d in g o f th e p ro c e s s v a r ia b l e s , p ro c e ss u n i t s , and p ro c e s s schemes w hich p ro v id e more d e s ir a b le c h a r a c t e r i s t i c s .

Share

COinS