7/28/2019 Hydrocrackir4g i t 4 Static and Ebulat1;Ig Bed Reactor Systems

1/7

45

HYDROCRACKIr4G I T 4 STATIC AND EBULAT1;IG BED REACTOR SYSTEMSS. A. Qader, W. H. Wiser, and.G. R. H i l l

Department o f Mine ral E ngineeringU nivers ity o f Utah, S al t Lake City, Utah 84112

1

',

J

AbstractThe r es ul ts o f hydrocracking o f coal and petroleum o i l s i n s ta ti c and ebulat-in g bed reactors are presented. The s ta ti c bed system was found to be moree ff ic ie n t at low space velocities , while the eff ic ie nc y o f both the systemswas almost the same a t higher space ve lo ci tie s wi th respect t o the y i e l d o fnaphtha. The gas o i l and coal o i l hydrocracking se veri ties , respectively,varied from 0.03 to 0.4 and 0.08 t o 0.45 i n the case of the s ta ti c bed systemand 0.03 to 0.31 and 0.07 to 0.32 i n the case o f the ebu la ting bed system.The s ta ti c bed system affec ted more des ulf ur iz ati on , deni trogenation, anddeoxyaenation a t lower soace ve lo ci tie s . whi le the ebu la ting bed system wasmore e f f i c i e n t a t highe r space vel oci tie s . The st a ti c bed system apnears t obe more s ui tab le f o r operations designed f o r the production o f naphtha andf o r the complete removal o f hete ro cyc li c compounds aIntroductionHydrocracking o f fuel o i l s i s mostly ca rried out i n s ta tic bed reactor systemswhich are very ver s ati l e f o r the processing o f d i s ti l l a te oi ls . They, however,pose some pro ble m i n the treatment o f heavy and resid ual o i l s . The re sid ualo i l s may give ri s e t o excessive deposits i n the bed leading t o catalyst deacti -vation, rea cto r plugging, and pressure drop i n the bed. This neces sitatesfrequent regenera tion and changing o f the c a ta ly s t which i s an expensive andtedious problem. The heavy feed stocks can eas tl y be processed i n an eb ulat-in g bed type o f rea ctor system as incorporated i n the H -o il process (1, 2 ) .I n the ebu la ting bed system, the ca ta ly s t bed expands i n excess o f the tru evolume o f the c ata lys t and the c ata lys t remains always i n a s tate o f randommotion caused by the ve loc ity of the feed o i l , hydrogen, and some in te rn a lcir cu la tion o f the o i l . This system has several advantages and can be employedf o r the processing o f d if fe re nt types o f feed stocks ranging from vacuum re s i-dues t o l i g h t gas o i l s ( 3 , 4).system has the advantage o f process ing heavy and res idual o i l s over the s ta ti csystem, whil e both the systems can be employed f o r the treatment o f d i s ti l l a teo i l s o f medium and low viscositles such as some gas o i l s and coal o i ls . Thereare no data avai lable a t this time i n the open l i te ra tur e on the r ela tiveeff ic iencies o f these two reactor systems f o r the processing o f ei the r petro-leum o r coal o i l and is, therefore, d i f f i c u l t to s elect the proper system fo rpra ctic al adaptatjon. This comnunication describes the res ults o f our inv es ti-gation on the evaluation o f the re la tiv e eff ic ie ncie s o f the st a tic and ebulat-in g bed reactor s ys tem i n the hydrocracking o f petroleum and coal o i l dis-ti1 ates .

It s , thus, evident tha t the ebula ting bed

7/28/2019 Hydrocrackir4g i t 4 Static and Ebulat1;Ig Bed Reactor Systems

2/7

46

ExperimentalM a t e r i a l s .The gas oil was prepared from a mixed base petroleum crude and ' the coal o i l wasob tain ed by the ca rbo niz atio n of a high v o la t i le , bi tuminous coal f rom Utah a t650C i n a labora tory oven (Table I ) .s u l f i de s of n icke l and tungs ten on s i l i ca - a lum ina i n 1 /16 th- inch s i z e pe l l e t swas used as th e hydrocracking c a t a l ys t .

A d u a l - fu n c t i o na l c a t a l y s t c o n t a in i n g

Equipment.T h e s t a t i c bed r eac to r s ys tem (F igu re 1 ) con ta ined a tubu la r 316 - s t a in le s s s t ee lr e a c t o r o f 0.75- inch d iameter and 40-inch length.1 s t was used in th e rea cto r .37 contained a reactor of 3- inch in ternal d lameter and 9- inch heighte b u l a t i o n o f the c a ta ly s t was main ly caused by a magnetic dr i ve s t i r r e r of 1800r . p . m . The t o t a l volume of t h e c a t a l y s t bed was 500 C . C and 250 c +c o f thec a t a l y s t was used f o r the experimental work.Hydrocracking procedure.

One hundred c . c of t he c at a-The ebu la t i ng bed rea ctor sys tem (Figure s 2 andThe

Both systems were f i r s t f lushed and pressurized with hydrogen and heated to thereac t ion t empera tu re , The pr es su re was then adju sted t o the experimental valueand th e o il was fed a t the d e s i r e d r a t e .c a r r i e d o ut a t a c o n s t a n t p r e s s u r e of 2000 p .s . i . and the hydrogen t o oi l feedr a t io was main ta ined a t about 1000.react ion tempera ture o f 450C un less ot he rw ise mention ed. The valu es of spa cev e l o c i t i e s v a r i e d i n the rang e of. 210% and were rounded o f f . I n t he cas e o ft h e s t a t i c bed r e a c to r , the exper iments were car r ied out a t 1 t o 6 spacev e l o c i t i e s ( V . of o i l / h r . /V . of c a t a l y s t ) , I n the ebula t ing bed reactor sys tem,experiments were carr ie 'd out a t 2 , 5 t o 6 space veloci t ies and the resu l ts wereex tra po lat ed down t o 1-space ve loc ity . Experiments .could n o t be ca r r i ed ou t a ts pa ce v e l o c i t i e s lo we r t ha n 2 .5 due t o p r a c t i c a l d i f f i c u l t i e s , I n t h i s s y s t e m ,th e ca t a l y s t (250 c . c ) expands t o a total volume o f 500 c % c c a t a l y s t bedvolume) and, hence, the space ve lo ci t i es were ca l cu l a te d on the ba s is of 500c . c o f t h e c a t a l y s t volume. The product was cooled i n the condenser and t h el i q u i d produc t was co l l ec ted in the s epa ra to r .some uncondensed o i l was passed throu gh an ac t i v e carbon tower t o adsorb theo i l and a gas meter to measure the r a t e a nd t o t a l volume pa sse d. The l i q u i dproduct was d i s t i l l e d and the f r a c t i o n b o i l i n g u p ' t o 200'C was designated asnaphtha and the r e s idu e a s middle d i s t i l l a t e .from the to ta l gas and i t s compos it ion .pass ope ra t ions . The r a t i o o f n a p h t h a plus gas t o the feed i s des ignated asc r a c k i n g s e v e r i t y .

The hydrocracking reactions wereThe data presented were obtained a t a

The gaseous product containing

The yield o f gas was calculatedThe an al ys es of th e pro du cts were done by sta nd ar d methods.

A l l products were obtained i n s i n g l e

Res u l t s and Discussion

I

f

S e l e c t i o n o f a su i tab le process ing sys tem main ly depends u p o n the type of. feedstock t o be processed and th e natu re o f products des i red .pa ted deve lopmen t o f . s yn the t i c o i l i ndus t ry in the nea r fu tu re , f eed s tockswidely vary ing in phys ica l and chemical p ro pe rt ie s wi 1 1 be avai lab le andDue t o t h e a n t i c i -

7/28/2019 Hydrocrackir4g i t 4 Static and Ebulat1;Ig Bed Reactor Systems

3/7

4 7

differe nt types o f process ing systems may have to be employed fo r th e i r tre a t-ment It s, therefore, necessary t o consider the dif fe re nt types o f reactorsystems avai lable and evaluate th e ir re la tive eff ic ienc ies f o r the processingof different feed stocks. A re a l i s ti c evaluation can only be made by process-ing the same feed stock under si mil a r reac tion cond itions i n d if fe re nt systems.The gas o i l and the coal o i l used i n th i s work were d i s ti l l a te s o f medium vis -co si ty and can be eas ily processed i n ei the r s ta ti c o r eb ula ting bed systemwithout problems, so that a reasonably good evaluation of the two processingsystems can be made.ing of gas o i l (F igure 4) i l lu s tra te d that both systems are almost equallyeff ic ien t a t space vel oc itie s greater than 4.amounts o f naphtha and middle d i s t i l l a te a t 430" and 450'C.naphtha, however, was very low and va rie d between 2 and 3%.exhibited different eff ic iencies at lower space velocit ies with respect tothe yiel ds o f naphtha and middle d is t i l l a te ,and 4.0, the s ta ti c system yi e ld ed more naphtha and, correspondingly, lessmiddle d i s t i l l a te when compared t o the ebu la ting bed systemni f i ca nt d if fe rence i n the y ie ld o f the gaseous produc t. The re s ul ts obtainedunder the experimental condi tions employed, in di cate that the static bed sys-tem i s more s ui tab le f o r hydrocracking operations ma inly designed fo r naphthaproduction, while both systems are equally suitable i f middle d i s t i l l a te pro-duction i s des ired. This i s further i l lus tra ted by the s imi la r data obtainedi n the hydrocracking o f a coal o i l (F igure 5) which, however, yield ed r el a tiv el ymore naphtha and les s gas. The l a t te r probably i s due to the diffe rence s i nthe bo i l i ng ranges and the composition o f the two feed stocks. The s ta ti c bedsystem ex hi bi ted high er cra cking s ev er iti es when compared t o the ebu la ting bedsystem a t lower space vel oc itie s (F igure 6). The gas o i l and coal o i l hydro-crac king s eve riti es , res pec tively, varie d from 0.03 t o 0.4 and 0 08 to 0.45 i nthe case o f the s ta ti c bed system and 0.03 t o 0 31 and 0.07 to 0.32 i n the caseo f the ebulating bed system. The res ults indi ca te th a t the product dis tribu -ti o n obtained i n the s ta ti c bed system i s being influe nce d very much by thespace ve loc i ty , whi le the l a tte r i s not very c r i t i c a l i n the case o f the ebulat-ing bed system. I n any system the ef fic ie nc y o f contact between the c ata lys tand the reactants i s mainly affe cted by the s iz e o f the c ata lys t and thespace velocity. It appears tha t the space velo city i s a more c r i ti c a l fa cto ri n the operation o f the s ta ti c bed system, whi le the s ize o f the catalyst i sprobably more c r i ti c a l i n the case o f the ebulating bed system.The product di s tri bu tio n a t di ff er e nt le vels of naphtha formation (Figures 7 and8) indi ca tes th a t both systems a ff ec t the product yie lds i n a s imi la r manner.The actual quantities, however, depend upon the nature o f the feed stock. Thepro per ties o f the naphtha and middle d i s t i l l a te produced by the two systems werefound to be quite similar (Tables I 1 and 111) The coa l o i l naphtha was,however, more aromatic i n nature than the gas o i l naphtha. The composition o fthe gaseous produc t was somewhat d i f fe re n t and the s ta t i c system produc t fromgas o i l contained more C hydrocarbons wh il e the eb ula ting system product con-ta ined more C1 and C2 hy!rocarbons. The s ta t i c system prod uc t from coa l o i lcontained more C3 hydrocarbons, wh il e the ebula ting system prod uct containedmore C1 and C2 hydrocarbons. The produc tion of m r e C1 and C2 gases i n theebulating bed system i s in di c a tiv e o f the occurrence o f more thermal crackingreactions i n th is system.

The product di s tr ib ut io n data obtained i n the hydrocrack-They yielded almost the sameThe y ie ld of

Both systemsA t space velocities between 1.0

There was no sig-

7/28/2019 Hydrocrackir4g i t 4 Static and Ebulat1;Ig Bed Reactor Systems

4/7

4 8

Removal of he te ro cyc li c compounds from fu e l o i l s i so f hydroc racking and the exten t of such hydroremovathe feed stocks, the ca ta lys t, and the experimentalone o f the major functionscon ditions. The type o fgas o i 1 hydrocracking,with space velocity i n thedepends upon the nature o f

proces sing system may a l s o have some in flu en ce : I ndes ulfu riz atio n and denitrogenati on varied l in e a rl ys ta ti c bed system, wh il e i t was no t the case i n the e bulatin g bed system wherethe des ulfu riz atio n and denitrogenation leveled o f f from a space velo city of 2and down (F igure 9) . The s ta ti c bed system was more e f f i c i e n t f o r the removalo f s u lf u r and nitr oge n compounds a t lower space v el oc iti es ranging from 1.O t o3.0, w h i l e the e bu la ting bed system was more eff ec tive a t higher space v el oc itie sranging from 4.0 t o 6.0:3 to 4 space velocities.83% were obtained i n the s ta ti c bed system a t a space ve lo ci ty o f 1.0. I n thecase o f the e bu a lti ng bed system, a maximum de s ul fu ri z a tio n o f about 75 % anddenitrogenation o f about 64% were obtained a t a space v el oc ity o f 2.0. A tspace ve lo c iti es lowe r than 2, there was no fu rth e r removal o f su l fu r andnitroge n from the gas o i l .very s uitable f o r ope rations designed f o r complete removal of sul fur and ni tro-gen from fuel oils, though it can remove about 70 to 80%, The obvious choice,then, w i l l be to employ the s ta ti c bed system f o r such ope rations,res ults were obtained i n the hydrocracking o f the coal o i l (F igure 10) whereinmaximum desulP uri zatio n and deni troge nation o f 97% and 87% were respe cti ve lyaf fected by the s ta t i c system and about 82% and 72% by the eb ulating bed system.Oxygen removal from coal o i l a ls o followed the s a w pattern as the removal o fs ul fu r and nitrogen. The rates o f hydrocracking of sulfur, nitrogen, and 'oxygen compounds o f gas o i l and coa l o i l appear t o be almost the same underconditions o f high seve rit ies, i rres pective o f the type o f processing systememployed. The rates , however, were d i f fe re n t under less severe c'onditions o fhydrocracking (F igu re 11). The mater ia l balance obtained i n the two systemswi th gas o i l and coal o i l i s g iven i n Table I V . A to ta l product recovery o fabout 102 to 103% was obtained, in di c a tin g 2 t o 3% o f hydrogen consumption i nthe process. The gas y i e l d was approximated t o about 0.5%.hydrogen sul fid e, ammonia, and water were ca lculate d from the ex ten t o f removalo f sul fur , nitrogen, and oxygen during the process.

The eff ici encies were almost the same i n the range o fMaximum de s ul fu ri z a tio n o f 96% and denitrogenation o f

It appears that the ebulating bed system i s no tAnalogous

The y ie lds o f

AcknowledgementResearch work was supported by the O ff ic e o f Coal R esearch and the U nivers ityo f Utah.

1I11iJi

II

,II

II

I

I

1

,i1

/

iI

,

,

1

7/28/2019 Hydrocrackir4g i t 4 Static and Ebulat1;Ig Bed Reactor Systems

5/7

49

Literature Cited1. Hellwi K . C . , Feigelman, S . , Alpert, S . B . , Chem. Eng. Progress, 62 No.

I 8 , 71 Qi966).2 . Rapp, L. M., Van Driensen, R . P . , Hydrocarbon Processing, 44, No. 12, 103(1965).

\

3. Chervenak, M. C., Johanson, E . S . , Johnson, C . A . , Schuman, S . C. , Sze, M . ,The Oil and Gas J . , 58, No. 35, 80 (1960).4. Chervenak, M. C . , Johnson, C. A . , Schuman, S . C . , Petrol . Refiner, 2,No . 10, 151 (1960).

7/28/2019 Hydrocrackir4g i t 4 Static and Ebulat1;Ig Bed Reactor Systems

6/7

50

I

Table I. Analysis of the feed materials.

Gravity, "APISul fur , w t . %F J itrogen, w t . %Oxygen, w t . %D i s t i l l a t i o n dataI.B.P., "C50% d i s t i l l a t e , O CF.B.P., "CHydrocarbon types, vol . %(neutral oi1)Aromatics t o l e f i n sSaturates

Coal o i l11.50.840.926.84

20030 539 5

68.032.0

Petroleumo i 131.800.940.80-

30034044029.071,O

I

Table 11. P roperties o f products o f gas o i l .Temperature: 450"C, pressure: 2000 p.s .i .,sp. vel.: 4.0Ebulat ingP roducts S ta ti c bed bed

Aromatics, vol. X 31.O 30.0Saturates, vol. % 66.0 66.0Olef ins, vo l . % 3 0 4.0Sulfur , w t. % 0.14 0.21Nitrogen, w t . % 0.18 0.26Aromatics t o le f ins , vo l , % 30.0 31.OSaturates, vol. X 70.0 69.0Die se l index 51.O 50.0C 1 10.0 15.0c2 12.0 14.029.0 28.0

49.6 43.0

Naphtha I

Midd le d i s t i l l a te I

Gas, v o l . Z1c3c4

7/28/2019 Hydrocrackir4g i t 4 Static and Ebulat1;Ig Bed Reactor Systems

7/7

51

Table 111. P roperties o f products o f coal o i l .Temperature: 45OoC, pressure: 2000 p.s.i.,sp. vel .: 4.0

ProductsNaphthaAromatics, vol . %Saturates, vol . %Olef ins, vol. %

Sulfur , w t . %Nitrogen, w t . %Acids, vol. %Bases, vol. %Neutral oi l , vol . 4:Aromatics + olef ins, vo l . %Saturates, vol. %Diesel index

Middle d is t i l la te

Middle d i s t i 1 a te (neutral )

Gas, vol. %C1c 2c3c4

S tat ic bed42.054.04.00.110.218.51 .o90.0

61.O39.041-013.015.033.039.0

Ebulatingbed44.O53.03.00.130.28

11.o1.789.O60,O40.041.O16.019.025.O40.0

Table I V . Material balance.Temperature: 450C, pressure: 2000 p.s.i.,sp. vel .: 4.0Product yield,ut. % S ta tic bed system E bul atin g bed systemGas-i l Coa l o i r Gas o i l Coal o i lNaphtha 5.0 10.0 4.0 9.0M iddle disti1 ate 96.O 91.o 97.0 92.0Gas 0.5 0.5 0.5 0.5Water - 1.o - 1.oHydrogen sulfide . 0.5 0.5 0.5 0.5Amnoni a 0.5 0.5 0.5 0.5