Thermal Hydrocracking BITUMEN With PILOT PLANT

8/13/2019 Thermal Hydrocracking BITUMEN With PILOT PLANT

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THERMAL HYDROCRACKING OF ATHABASCA BITUMEN:COMPARISON OF COMPUTER-SIMULATED FEED AND

PRODUCT VAPORIZATION VALUES WITH PILOT PLANT DATA

D . J . Pa tmore and B . B . P r u d e n

E n e r g y R e s e a r c h L a b o r a t o r i e sCanada Cen t re f o r Minera l and Energy Techno logy

Department of Energy, Mines and Resource s555 B o o t h S t r e e t , O t t a w a , O n t a r i o , C a n a d a , K l A O G 1

INTRODUCTION

Th e En e rg y R es e ar c h L a b o r a t o r i e s o f t h e C ana da C e n t r e f o r M i n e r a l a n dEnergy Technology (CANMET) a r e e ng ag ed i n a c o n t i n u i n g u p gr ad i ng p r o j e c t i n v o l v i n gt h e h y d r oc r a ck i n g o f C a n ad i a n o i l s an d b it u m en an d he av y o i l . S u ch u p g ra d i ng i sn e c e ss a r y t o r emove s u l p h ur an d t o r e d u c e t h e v i s c o s i t y o f t h e bi t um e n t o f a c i l i -t a t e t r a n s p o r t by p i p e l i n e t o t h e r e f i n e r y . C u r r en t l y up gr ad in g i s accomplished ona commerc ial s c a l e by Great Canad ian O i l S a n ds L i mi t e d u s i n g a c o k i n g p r o c e s s w h i c hc o n v e r t s u p t o 20 o f t h e b i t u me n t o c h a r . One a im of t h e CANMET work i s t o d e -v e l o p a n e co n om i ca l p r o c e s s w h i c h w ould c o n v e r t a l l of t h e b it u me n t o u s a b l ep r o d u c t s , a n d t h u s r e d u c e t h e was t e of a v a l u a b l e r e s o u r c e . For t h i s p ur po se ao ne -b ar re l- pe r- da y p i l o t p l a n t was b u i l t an d h a s be en o p e r a t e d s u c c e s s f u l l y w i t h av a r i e t y o f f e e d s t o c k s . T h i s work h a s c o n c e n t r a t e d o n b o t h p l a n t o p e r a b i l i t y , i np a r t i c u l a r t h e pr e v e nt i o n of r e a c t o r c ok i ng ( l ) , and on t h e e f f e c t o f o p e r a t i n gc o n d i t i o n s on y i e l d s and p r od u c t q u a l i t i e s 2 ) .

E f f i c i e n t and e co no mi ca l sc al e- u p o f t h i s pr o c e ss t o a commerc ia l - s i zep l a n t r e q u i r e s q u a n t i t a t i v e k no wl ed ge o f b o t h t h e d e g r e e o f v a p o r i z a t i o n of f e e dand p r o d uc t a nd t h e f r a c t i o n o f t h e r e a c t o r o c c u p i e d by g a s u n de r r e a c t o r c o n d i t i o n s .The l a t t e r , u s u a l l y r e f e r r e d t o a s v o i d a ge , h a s a l r e a d y b e e n i n v e s t i g a t e d i n d e-t a i l ( 3 ) . Such knowledge i s needed t o c a l c u l a t e h yd ro ge n p a r t i a l p r e s s u r e s andt r u e l i q u i d a nd v ap ou r r e s i d e n c e t im e s. T he se i n t u r n a r e ne c es s ar y t o a c c u r a t e l yestimate t h e s i z e of v a r i o u s p l a n t c o mp o n e n t s a s w e l l a s t o f o r m ul a t e a k i n e t i cmodel f o r t h e t h e r m a l h y d r oc r a c k in g r e a c t i o n .

Because i t i s n o t f e a s i b l e t o m ea su re l i q u i d and va p ou r c o m p o s i t io n s i nt h e r e a c t o r d i r e c t l y , r e c o u r s e m us t b e made t o c o m p u t a t i o n a l m e th o ds . T h es e i n -v o lv e e s t i ma t i ng t h e e q u il i b r iu m v a p o r i z a t i o n c o n s t a n t , K, f o r v a r i o u s c o mp o ne nt s oft h e s ys t em u s i n g k nown o r e s t i m a t e d v a l u e s o f t h e i r t he rm od yn am ic p r o p e r t i e s .

C o mp u ta ti o ns f o r t h e p r e s e n t s t u d y were c a r r i e d o u t u s i n g t h e Gr ay so n-

S t r e e d m o d i f i c a t i o n of t h e C ha o- Se ad er c o r r e l a t i o n e mp lo yi ng t h e p r i n c i p l e of c o r -r e s p o n d i n g s t a t e s 4 , 5 ) . A package program was employed.

Va p ou r - li q u id e q u i l i b r i u m d a t a were o b t a i n e d f r om m e as u re m en t s i n a h o ts e p a r a t o r d ow n st r ea m o f t h e p i l o t p l a n t r e a c t o r . T h i s w el l- mi xe d s e p a r a t o r , w hi chwas t e m p e r a tu r e c o n t r o l l e d , w a s assumed to behave a s a s i n g l e s t a g e c o n t a c t o r , a ndmea su re me nt s o f l i q u i d a n d v a p o u r f l o w s an d c o n c e n t r a t i o n s w e r e t a k e n a t s t e a d yS t a t e c o n d i t i o ns .

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EXPERIMENTAL

The p i l o t p l a n ti s

shown s c h e m a t i c a l l y i n F i g .1

Bitumen and hydrogena r e f e d a t t h e b o tt om o f a l o n g un p ac ke d h e a t e d t u b u l a r c ol umn ( 3 . 8 1 c m diam. x3 .95 m l o n g ) . T he h y d r o c r a c ke d p r o d u c t s a r e l e d f ro m t h e t o p o f t h e r e a c t o r t o ah o t s e p a r a t o r k e p t a t a t e m p e r a t u r e b el ow t h a t of t h e r e a c t o r . The h ea vy o i lp r o d u c t i s w i t hd r a w n a nd t h e v a p o u r p a s se d i n t o a c o l d r e c e i v e r an d c o n d e n s e d. Th el i g h t o i l p ro duc t i s a g a i n w i t h d r a w n a n d c o l l e c t e d .mixed a s t h e r e a c t o r p r o d uc t s e n t e r ed b elow t h e l i q u i d l e v e l , and t h e r e w a s a h i g hr a t i o of g as t o l i q u i d . I t f o ll o ws t h a t t h e f r a c t i o n o f l i q u i d v a p or i ze d , f , w a st h e we ig ht of l i g h t o i l p r od u ct d i v i d e d by t h e t o t a l l i q u i d p r o d u ct . The ho t se p-a r a t o r w as t e mp e ra t ur e c o n t r o l l e d so t h a t t h e ab ov e r a t i o c o ul d b e o b t a in e d a s af u n c t i o n of t e m p e r a t u re . T he g a s f lo w was m et e re d u s i n g t h e o r i f i c e , and t h e g a sc om po si ti on a t t h e r e a c t o r i n l e t c o n t r o l l e d b y sc r ub b in g . A cc or di ng ly t h e a c t u a lg a s c o m p o si t i on a nd f l o w i n t h e h o t s e p a r a t o r c o u l d b e c omp ut ed b y u s i n g t h e s e d a t aa l o n g w i t h d i s s o l v e d g a s f l o w s an d c o m p o s i t i o n s , r e a c t i o n h yd r og e n r e q u i r e m e n t s a ndhydrocarbon gas make .

T he h o t s e p a r a t o r was w e l l

A t h a ba s c a b i t u me n c o n t a i n i n g 5 1% p i t c h ( m a t e r i a l b o i l i n g a bo v e 524OCe q u i v a l e n t a t m o s p h er i c b o i l i n g t e m p er a t u r e) w a s f e d i n a l l c a s e s . P r od u ct s a r ei d e n t i f i e d b y t h e amount o f p i t c h c o n v e r s i o n ba s ed on f e e d .g i v e n i n R e fe r en c e 6 .

F u r t he r d e t a i l s a r e

T h e c o m p u t e r s i m u l a t i o n w a s c ar r i ed ou t f o r CANMET by Sa tu rn Eng in eer ing ,C a l g a r y, A l b e r t a , u s i n g t h e DISTILL p ro g ra m l i c e n s e d b y t h e Chem S h a r e C o r p o r a t i o n ,H o u s to n , Te x as . S i mu l a t i o n s were c a r r i e d o u t f o r A th ab a sc a b i tu me n an d f o u r t y p i -c a l h y dr o cr a ck e d p r o d u c t s c o v e r i n g t h e r a n g e 4 9 t o 93% p i t c h c o n v e r s i o n . I n p u t t ot h e p ro gr am c o n s i s t e d o f l i q u i d a n d g a s r a t e s , c o m p o si t i o n s a nd p r o p e r t i e s . Thec o m p o s i t i o n a nd p r o p e r t i e s o f l i q u i d f e e d an d p r o d u c t w er e a p p ro x i ma t e d b y t e n

f r a c t i o n s wi t h mean aver ag e bo i l i n g p o i n t s ran g i ng f rom 65.5OC (150OF) to 648 .9OC1200OF).

e a c h c u t , u si ng s t a nd a r d c o r r e l a t i o n p r o c ed u r es f o r p et ro le um f r a c t i o n s .T h e s e f r a c t i o n s were d e r i ve d from Hempel d i s t i l l a t i o n s and g r a v i t i e s of

For e a c h s p e c i f i e d t e m p e r a t u r e an d p r e s s u r e co m b in a t io n t h e p ro gr am c a l -c u l a t e d f , t h e w ei gh t f r a c t i o n o f l i q u i d t h a t v a p o r i z e s u nd er t h e s p e c i f i e d c o n d i-t i o n s , a s a f u n c t i o n of s p e c i f i e d v a l u e s of G / L , t h e r a t i o of g a s r a t e a t STP ( i ng m ol /h ) t o l i q u i d r a t e a t STP ( i n k g / h ). G a s c o m p o s i t i o n w as a l s o e n t e r e d a ndt r e a t e d a s a p ar a me t er .

RESULTS A N D DISCUSSION

C a l c u l a t e d v a l u e s o f t h e d e g r e e o f v a p o r i z a t i o n w e r e p l o t t e d a s f u n c t i o nso f G / L a n d t e m p e r a t u r e ( F i g s . 2 t o 5 ) . From t h e s e g r ap h s i n t e r p o l a t i o n s c a n b emade t o o b t a i n f v a l u e s a t c o n d i t i o n s o t h e r t ha n th o se s p e c i f i e d . F i g u r e s 2 and 3i l l u s t r a t e t h e e f f e c t of G/L o n f f o r d i f f e r e n t p r e s s u r e s and t e m pe r a tu r e s f o r b i t u -men a nd f o r a h y d r o c r a ck e d p r o d u c t w i t h 9 3% p i t c h c o n v e r s i o n . T he t r e n d i s a n i n i -t i a l r a p id i n c r e a s e i n f f o l l o we d by a g e n er a l f l a t t e n i n g o u t of t h e cu r v e , a t r e n dw h ic h becomes m or e p r on o un c ed a t h i g h e r t e m p e r a t u r e s an d p r e s s u r e s . T h i s r e f l e c t st h e p r e s e n c e of a v e r y h i g h b o i l i n g f r a c t i o n ( p i t c h ) w h ic h i s v a p o r i z e d t o o n l y as m a l l e x t e n t . A s i m i l a r t r e n d i s seen when f i s p l o t t e d a g a i n s t t e mp e ra t ur e a ssh ow n i n F i g s . 4 a n d 5 f o r b i t u me n an d 3 h y d r o c r a c k ed p r o d u c t s ( 4 9 , 7 6 a nd 9 3% p i t c hc o n v e r s i o n ) a t 1 0 . 4 4 MPa a n d v a r i o u s G/L v a l u e s .h i g h c o n v e r s i o n c a s e r e a ch e d v e r y h i g h v a l u e s .

The d eg r e e of v a p o r i z a t i o n i n t h e

The e f f e c t of p r e s s u r e on f i s a l s o i l l u s t r a t e d i n F i g s . 2 and 3 . Fo rt y p i c a l c o n d i t i o n s of 45OoC a nd G / L = 4 0 g m o l lk g , i n c r e a s i n g p r e s s u r e fr om 1 0 . 44 t o1 7 . 3 4 MPa dec rea ses f by 50% f rom 0 .37 t o 0 .1 8 5 f o r A t ha b a s c a b i t ume n , a nd b y 2 0 % ,

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f r o m 0 . 8 6 t o 0 .6 9 f o r p r o d u c t h y d r o c ra c k e d t o 93% c o n v e r s i o n ; w h i l e f o r G/L = 1 0 ,f i s d e c r e a s e d b y 54 % a nd 4 4% r e s p e c t i v e l y.

A no th er f a c t o r w h ic h i n f l u e n c e s t h e d e g r e e of v a p o r i z a t i o n i s t h e g a sc o m po s i ti o n ; i n c r e a s i n g t h e c o n c e n t r a t i o n o f h yd ro ge n c a u se s a d e c r e a s e i n f . T h i si s i l l u s t r a t e d i n F i g . 6 f o r 35OoC a n d 1 3 . 8 9 MPa f o r a p r o d u c t h y d r o c ra c k e d t o 8 3%c o n v e r s i o n . In t h e r a n g e 5 0 t o 90 mol % H2, f i s l i n e a r l y p r o p o r t i o n a l t o h ydr og enc o n c e n t r a t i o n . F o r a l l hydrocracked p roduc t s , f w a s c a l c u l a t e d f o r b o t h 6 0 a nd 8 0mol % ; f o r mo st c a s e s s t u d i e d a n i n c r e a s e o f 3 3 % f r om 60 t o 80 mol H 2 c a u s e d a na pp ro xi ma te 1 0% d e c r e a s e i n f .

Av e r a g e l i q u i d r e s i d e n c e t i m e s ( t ) c a n be c a l c u l a t e d f ro m t h e s e v a p o r i z a -t i o n f i g u r e s by t a k i n g a v e ra g e v a l u e s f o r b it um en an d h y dr o cr ac ke d p r o d u c t , a f t e rmak in g a l l o w an c e f o r t h e f r a c t i o n of r e a c t o r v o lu me o c c u p i ed b y g a s ( v o i d a g e ) , a sf o l l o w s :

t = [ ( r e a c t o r v o l )x ( l- v o id a ge ) ]/ [ ( v o l o f l i q u i d f e d p e r h ) x ( l - a v e . f r a c t i o n v a p o r i z e d )

Such c a l c u l a t i o n s were c a r r i e d o u t f o r a s e r i e s of p i l o t p l a n t r u n s a sshown i n F i g . 7 , w h er e t h e p r o d u c t of a v e r a g e r e s i d e n c e t i m e a nd l i q u i d h o u r l y s p acv e l o c i t y LHSV) w er e p l o t t e d a g a i n s t t h e t e m p er a t ur e a t which each hyd rocrackedproduc t w a s o b t a i n e d . The a v e r a g e f r a c t i o n v a p o ri z e d was t a k en a s t h e a v e r a g e o ff f o r b it u me n a n d f o r p r o d u c t . A s e a c h p r o d u c t r e p r e s e n t e d a d i f f e r e n t p i t c h c on-v e r s i o n , a nd a s t h e c om pu te r s i m u l at i o n g av e v a p o r i z a t i o n v a l u e s o n l y f o r a l i m i t e dnumber of products a t f i x e d c o n ve r s io n s , a l i n e a r i n t e r p o l a t i o n was u se d t o c a l c u -l a t e v a l u e s f o r t h e s e i n t er m e di a te c o n ve r s io n s . A s i m i l a r i n t e r p o l a t i o n w a s a l s ou se d t o c o r r e c t f o r d i f f e r e n t hy dr og en c o n c e n t r a t i o n s . F i g u r e 7 sho ws t h a t t h ec a l c u l a t e d r e s i d e n c e t i m e s a r e v e r y s e n s i t i v e t o r e a c t i o n t e m pe r a tu r e , a nd becomei n c r e a s i n g l y h i g h e r t h a n t h e no mi n al s p a c e t im e a s t e m pe r a tu r e an d s p a c e v e l o c i t y

i n c r e a s e .

A lt ho ug h e x pe r i me n t al v a p o r i z a t i o n d a t a f o r t h e r e a c t o r were n o t a v a i l -a b l e , i t w a s p o s s i b l e t o t e s t t h e c om p ut er s i m u l a t i o n b y co mp a ri n g t h e c a l c u l a t e dv a l u e s of f w i t h e x p er i m en t a l d a t a o b ta i n e d a t l ow e r t e m pe r a tu r e s f o r t h e h o ts e p a r a t or wh er e v a p o u r / l iq u i d r a t i o s a r e r o u t i n e l y m e a s u r e d .c a l c u l a t e d by co mp u te r w e re i n t e r p o l a t e d t o c o r r e c t f o r p i t c h c o n v e r s i o n and h y dr o-g en c o n c e n t r a t i o n f o r e a c h r u n c o n s id e r e d . To t e s t t h e d a ta f o r b it um en i t s e l f as e r i e s o f r u n s were c a r r i e d o u t w i t h b o t h r e a c t o r a n d h ot s e p a r a t or a t 35OoC and37OoC a t w hi ch t e m p e r a t u r e s h d r o c r a c k i n g r e a c t i o n s o c c u r t o o n l y a l i m i t e d e x t e n t

2 3 % p i t c h c o n v er s i on a t 3 7 0 C ) . C a l c u l a te d v a l u e s were p l o t t e d a g a i n s t e x p er i -m e n t a l d a t a ( F i g . 8 ) . The b e s t l i n e f i t t e d t h e e qu at io n:

A g ai n t h e f v a l u e s

8

FE = (3 . 3 0 .9 ) (0 .85 ? 0.07)FC

where FE and F a r e e x p e r i m e n t a l a n d c a l c u l a t e d v a l u e s of t h e p e r c e n t o fl i q u i d v a p o r i z e d . T he a g re e me n t i s r e a so n a bl e c o n s i de r i ng a l l t h e p o s s i b l e s o u rc e sof e x p e r i m e n t a l e r r o r , and i n f a c t FE and FC a r e i n c l o s e a g re em en t a bo v e a b o u t 1 5 % .

C

The r e s u l t s f o r h yd r oc r ac k ed p r o d u c t s a r e shown in F ig . 9 , i n wh ich 75d a t a f rom p i l o t p l a n t r u n s c a r r i e d o u t u nd er a v a r i e t y of c o n d i t i o n s a r e c om pa re dw i t h c a l c u l a t e d v a l u e s . P r e s s u r e r a n ge d fr om 1 0. 44 t o 1 7. 34 MPa, a n d t e mp e r a t u r efro m 300 t o 43OoC.l i n e l i e s c l o s e t o t h e d i a g o n a l and i s g i v e n by t h e e q u a t i o n :

A l t h o u g h t h e r e i s c o n si d e ra b l e s p r e ad i n t h e d a t a , t h e b e s t

CE = ( 1 . 8 1 . 2 ) (0.95 0 .04 )F

I t i s b e l i e v e d t h a t much o f t h e s p r e a d i s c a us e d by e x p e r i m e nt a l e r r o r ,p a r t i c u l a r l y i n m ea su re m en ts of g a s r a t e a nd c o m p o s i t i o n w he re e r r o r s of ? 5% o r

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G / L = 20 g m ~ i / k g4OO0C 6 , %a 450C 6 Xa A Z b

Bi tumen 0 .1175 8 . 5 0 .2 41 8 . 3 1 0 5 . 1193% Pr od . 0.505 1 4 . 6 0.712 3.2 29.1

a P e r c e n t a g e i n c r e a s e i n f f o r a 1 2. 5% i n c r e a s e i n G / L .P e r c e n t a g e i n c r e a s e i n f f o r a 1 2. 5% i n c r e a s e i n T.

G / L = 40 g mollkg4OOOC 6 , %a 45OoC 6 , % A %b

0.205 10.0 0.378 4.2 84.40.672 4.2 0.860 1.7 28.0

I t i s s e e n t h a t f o r a 1 2 . 5 % i n c r e a s e , t e m pe r a t ur e h a s a g r e a t e r e f f e c t t h a n G/L.H ow ev er , a s t h e a c c u r a c y o f t e m p e r a t u r e m e a s u re m e nt s i s m u c h g r e a t e r t h a n t h o s e ofG / L d e t e r m i n a t i o n s , t h e e r r o r s a r e p ro b a b ly of s i m i l a r m ag ni tu de .

E r r o r s c a n a l s o be i n t r o d u c e d by t h e a p p r o x i m a t io n s u s ed i n t h e i n t e rp o l a t i o n s f o r p i t c h c o n v e r s i o n a nd h yd ro ge n c o n c e n t r a t i o n s , a s w e l l f r o m d i s c r e p -a n c i e s be tw ee n s i m u l a t e d a nd a c t u a l l i q u i d a nd g a s p r o p e r t i e s .

CONCLUSIONS

C om pa ri so n o f c a l c u l a t e d v a l u e s of l i q u i d v a p o r i z a ti o n u s i ng a computers i m u l a t i o n w i t h e x p e r i m e n t a l d a t a i n d i c a t e d t h a t s u c h c o m pu t a t i o n a l m et ho ds w i l lg i v e r e as o n a bl y a c c u r a t e v a l u e s f o r t h e d e g r e e of v a p o r i z a t i o n , c o n s i d e ri n g t h ea p p ro x im a ti o n and e x p e r i m e n t a l e r r o r s i n v o l v e d , f o r a v e r y h ea vy o i l s u c h a s t a rsand bi tumen and i t s h y d r o c r a c k e d p r o d u c t s .

REFERENCES

1 M e r r i l l , W. H . Logie , R.B. and Denis, J . M . A p i l o t s c a l e i n v e s t i g a t i o n ofthe r ma l hydroc ra ck in g of Athaba sca b i t umen ; CANMET ( Ca na da C e n t r e f o r M i n e r a land Energy Technology, fo rm er ly Mines Branch, Department of Energy, Mines andResou rces) R es ea rch Re por t R-281; Dec. 1973.

2 . Pruden , B . B . , L o g i e , R . B . and Den i s , J . M . Thermal hydrocracking of Athabascab it um e n: R e d u c t i o n o f r e a c t o r f o u l i n g ; CANMET Re por t 76-33; Aug. 197 6.

3. Shah, A.M., Pruden , B.B. and Den i s , J . M . Thermal h ydroc rac k ing of Athabascab i tu m e n: C o r r e l a t i o n o f r e a c t o r v o i d a g e i n v e r t i c a l t w o- ph as e f lo w ; CANMETRep ort 77-48; Dec. 1976.

4. Chao, K . C . and Seade r, J . D . A g e n e r a l c o r r e l a t i o n of v a po u r- l iq u id e q u i l i -b r i a i n hy d ro c a rb o n m i x t u r e s ; A m Ins t . Chem. Eng . Journ . ; v. 7 , no. 4, p 598;D e c . 1961.

5. Grayson, H.G. a n d S t r e e d , C . W. Vapour l i q u i d e q u i l i b r i a f o r h i g h t e mp e r a tu r e ,h i g h p r e s s u r e h y dr o ge n - hy d ro c a rb o n s y s t e m s ; P r o c . V I t h World P e t r o l . C o n gr. ,F r a n k f u r t f M a i n ; Se c t . V I I , pap er 20, P07, p 233; Jun e 196 3.

6 . Pruden , B.B. and Den i s , J . M . H ea t o f r e a c t i o n a nd v a p o r i z a t i o n of f e e d a nd

p r o d u c t i n t h e t h e r m a l h y d r oc r a c k i ng o f A t h a b a s c a b it um en ; CANMET Repor t76-30; Apr. 1976.

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Thermal Hydrocracking BITUMEN With PILOT PLANT

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