US2326525A - Method of preventing deleterious coke deposits - Google Patents

Description

Aug. 10, 1943. R. J. DlWoKY METHOD OF 'PREVENTING DELETERIOUS COKE DEPOSITS Filed Aug. 28, 1940 3 Sheets-Sheet l FIG.'1

lll/11111 llllllllllllllIl/llllll Il lllllll im I ROY 'J. DlwoKY H/S ./I TTORNEY Aug. 10, 1943. R. J. DlwoKY METHOD OF PREVENTING DELETERIOUS COKE DEPOSITS 3 Sheets-Sheet 2 Filed Aug. 28, 1940 FIG. 2

R. J. DlwoKY 2,326,525

5 Sheets-Sheet 5 Aug. 10, 1943.

METHOD OFFREVENTING DELETERIOUS COKE DEPOSITS- Filed Aug. 28, 1940 wlllllrlllll/llllllllr wllllmllllill FIG. 4

ROY J. DlwoKY /N VENTO/e MMM@ H/s 17m/nv :Y

Patented Aug. 10, 1943 indiana lirpiicaennugestzs, 1940; serai-f ne 3545422' f y claims (c1.19s`69l This invention relates to Vcertainimprc'vemeirts y in the artofv crackinghydrocarbons'for thjepur.-

pose of removing coke formations'and preventing the buildingnp of deleterious coke formations in tl'i'e crackingapparatus.

It is an object of inyinvven-'tion'-tof'positivelllv c preventthe buildingup'fr deleterious' cokede` The invention pertains particularly to. means for maintaining the vapor transfer `lines fromv reactionA cl'lamlcersV freel from inj'uriogus colse d'eposits. A problem hasy heen presented, A particnfk larly in thevapor' phase or hightemperatu-re cracking'of hydrocarbonils, of'maintaining the vapor transit passages from the. reaction, cham#V bers free from harmfulgcoke deposits.Y Various schemes involving the introduction of, a; cooling, medium into the vapor linehaveheen employed.

It is, however, an.-extrernebl` delicate proposition immediately adjacent tothe vapor--outlet-2 the Ysprayed oil beingi'introduced inxsuch 'quantity that substantially alliof it, either-as` vapors or entrained liquid, Will-be carried out with Ythe outfiovving vapors. Due te the limitationsY im- V- rinsed` by the. necessity et avoiding the coolingof the mass of vapors inI the-reaction chamber, it has been found impossible when makingA runs of considerable length to. ccrnpletely'prevent the formation ci cokev deposits in the vapor line-o1 r adiacentthe entrance thereto-rand' resortl has posits the? vapor-'lirici In accordance withthe invention a.- coke knocking apparatus is provided carrying uid spraying lirnea'ns adapted for direct#- ing fluid under' considerable 'force "against the wal-l of the vapor linerand-adjacentparts. "By the periodicA applicationof "the*combined` knocking and spraying jdevi'ce thefcke is* ef'ectually removed from thevapor line and-*the building up ci" deleterious depositsrsu'ch as would necessitate a `shutdownisprevented. When the coke k'nocker comes, in ycontact any .coke beingiormed in the vaporlinegif itbeaof. a soft or tarry nature such aswould Aordinarily'loe nierely pushed,l aside c by thekno'cler, the fluid sprays eiectually nush out such soit'inaterialg, Y I'fj ther formation isfq'f a morebrittle natnrethefcoke knockerwill function been had to theuse of a coke'knocker for'p'eriodic operation foi'- remoVin-g the eolie deposit. The function of the coke knoclrer is to-break oie the' colte stalactites which form around the Spray tins. These coke stalactites if' not removed grow in sizeand eventually restrict thefvapor line open-v ing, thus causing anincreaseinpressure `until the safe operating pressureeon the reactionY cham# ber is reached` forcingtlie unit. to shut down;

oli is merely pushed aside: by the knocker and.A

may remainadiacent the vaporfoutlet in a oncli-v tion Well adaptedftcgform a nucleus for the hui-ld# ing upl of additional coke deposits andthe 'even-e tual formation ofliarder deposits-'that Willnot be reached-.or renewed'by the coke lniocker,Y necessitating the shutting down theunit.

tobreak it off While atltlijes'ame timethe spraying Huid will. thoroughly 'clean 'thevaporline Wall and adj acent` pnrtions ofthejvall of, lthe/reaction chamber.. Inthisway the use ofthe, spray ring for continuously spraying-oilv i'minmediately' adiafcent the entranceitdthe vapo-rj linemay lceQel'irriffV mated, since terioflicuse ofthe kweker' dement Y and its associated spraying mechanismymay be f relied on forkeeping thevapon linev free. from. coke deposits. 'Y t For the purpose. of moreiully disclosingr thev inventioncreference is no w had'torthe acccm- Y panying drawings Whereinz" Y Eig, v1 isaV sectional elevationf of. illustrating fthe inventionand` mmstitutingA an, embodiment thereof.;

i Fig2is.an enlarged partial sectionshovvinga y rotary assembly; for the'fluid, sprayingmeans;4

Fig.. 3 isa. plan lvie/vv takenialo'ng. line 3-3, of Fis. 2;.

ed form,l of the invention.r

Fig. 4 is a sectional elevation sl'iovving-amodi- -A In the drawings, lll. represents. areaction chamber for the: cracking orconversion of hydrocarbon cilsl` Usuallyr the hydrocarbonoil to be converted 'is passed through" a heating--coilfand-v delivered te thereaction chamber'wherein crack-1A ing. conditions. of temperature and pressurev are maintained. The vapor linen 'for the reactionY chamber' Ii-ncludesfafvertical riser section l IIl and a horizontal'sectioni12;' @ne end off thehorif zontal section-is cle-sedi byl a blind'ilange- I3 and the other 'end :extends to vsubsequent apiJara'tus `such as a -iractienatingV t'ovver (not sho-wnlj A' `an apparatus l Ymunication with the vapor line I2.

A pipe section I6 is provided in axial alignment with the vapor riser II yand in open com- .'I'he lpipe section I6 supports a cylinder I1 having actuating means (not shown) for impartinga reciprocating movement toa pistonl carrying a pipe I9. The pipe I9 is connected by means'of a series of pipe sections 2| interconnected by swing joints 22 to a suitable source of oil suppl under pressure.

Y is provided with a splined section or square sec-v At the lower end of the pipe I9 is mounted an element for rotary movement thereon carrying the spraying nozzles. The rotary assembly includes an upper casing 24,` secured to a lower casing 25 as by means of bolts 26. Ball bearings 21 are suitably mounted within a ball race element 28 fixed to the casing 24 and a ball race element v29 fixed to the pipe I9. isprovided with a plurality of discharge nozzles 30, adapted to dischargeiiuid tangentially to the pipe I9 so as to impart a rotary :movement to the casings 25 and 24, Itis advantageous to dispose the nozzles at various angles. Thus, as illustrated, a Vpair of nozzles on opposite sides of thecasing 25 are directed upwardly at an angleof about 45 from the horizontal while another'pair of nozzles fonopposite'sdes of the casing are directed downwardly at ank angle of about 45?. In practice, the nozzle openings are about 1/8 of an inchV to fa of an inch in diameter and are constructed so as to be capable of discharging. an even ystream of Vliquid *for a distance of at least 8 `feet.

Aplate or plunger element is"` secured to theybottom of the casing 25 kfor, the purpose of,

dislodging ycoke formations and protecting the nozzles. The plate or plunger 3L may assume various forms; for example, it1may be in the form Vof an inverted cone and "adapted to .have a mechanical cutting action. When the piston I8 is in the upper position, as shown in Fig. theplate 3l is seated at the bottom of pipe I0. closing the opening between lthe vapor line l2 and' pipe iF.. and when the piston is in thelower position the rotary nozzle assembly is.` in approximatelyv the position indicated infdotted lines in Fig. 1,- As the rotary assembly moved downwardly through the vapor riser 'II coke formations are dislodged, while the streamsl from the rotating nozzles wash. away any 'carry'l or coky materials and serveto clean and scour the surface of the vapor riser. It will be noted that the rotary assembly is adapted to proceed clownwardly somewhat below the upper wall of the reaction chamber so that fluid streams from. the nozzles may be applied to the upper surfaces of 'the reaction chamber adjacent the outlet opening.

In the modied form of the invention illustrated in Fig. 4 a fluid supply pipe 32 is adapted for both rotary and reciprocating movement.

The casing 25l Pigidly fixed to the lower end of the pine 1.2 is Y a cone shaped combination plunger and nozzle position, as shown in dotted lines in the drawing, may be seated in a casing 35 which may a1- so support a stufling box 36 through which the pipe 32 moves. It is advantageous to provide oil cooling for the stuing box. The pipe 32 :pipe 4I which is connected to a piston 44 dis- Iposed in a cylinder 45 suitably provided with actuating means,V (not shown) for imparting the desired upwardjand downward movement to the pipe. rYhe spraying fluid is supplied to pipe 4| by means of a series of pipe sections 42 interconnected by swing joints 43.

jIt is recommended thatI the spray uid be supplied under Ypressures of the order of 1500 to 2000 lbs. and that the luidbe delivered from thenozzles at arate of about 400 to 500 ft. per second. By supplying the iluid under such high pressure and by delivering-.the fluid from the nozzles at such high rates it is possible not only to readily remove any softv or tarry formations, but also to ,efiectuallyscour the wallsfrom any coke formations of a lhard nature which may have becomebaked thereon, e

In the practice of the invention the rotary nozzle assembly isnormally held in the upper position while preferablyI a substantially continuous stream of fluid may be discharged into the vapor line through line. I4. The operation is continued inthis way for atime, without the application of anycooling medium to the vapors entering the vapor riser, and coke Vmay lbe permitted to accumulate on thewallrof the vapor riser vor inthe zone immediately adjacent the outlet opening of the reaction chamber. By periodically operating the rotary plunger jand spraying nozzles any cokeiorrnations that may have lodged are eiectually removed.v Ordinarily itis necessary to operate the rotary plunger and `spraying' nozzles Aat intervals of about once cr twice Va day. And 'ity is Aonly necessary to carry on the spraying for brief periods such a min ute or at most two or ythree minutes.

The practice of the invention is well adapted for application in' pressure cracking processes wherein the oil is discharged from the heating coil attemperaturesof the order to 900 F. to 1000 F. into the reaction chamber wherein temperatures, usually in excess of 850 F. andoften approximating 900 F., are maintained and in whichrthe vvapors. are passed from the reaction chamber at temperatures in` excess of 800 F. In an example of the invention, condensate stocks having end boiling points suchas 650 F. 150.700 F. are subjected to vapor phase cracking by being discharged from the cracking coil at temperatures in excess of 900 F. into the reaction chamber wherein the mass of vapors'is maintained at temperatures of about 880 F. to 980 F. In the normal operation a continuous streamof cooling oil may be introduced through a line I4 into the vapor line I2 operating to cool the vapors somewhat and prevent coke deposition in the vapor line I2. The cooling medium is carried along with the flowing vapors and the mixture flows through the vapor Vline normally at temperatures of about 825 F. to 850 F. At intervals of about once or twice a day the coke knocker and spraying apparatus is applied to remove any coke deposits that may have formed in the vapor riser l! or in the top of the reaction chamber i9 adjacent the outlet. The effect of the spraying is to reduce the temperature in the vapor passages, but since the spray need only be conducted for the comparatively brief interval of a minute or two the reduction in temperature is only temporary and normal working conditions are readily reestablished. Steam may be discharged through the nozzles tocprevent the deposition to tarry materialtherein during period when the nozzles are not discharging oil.

Although a preferred embodimentof the invention has been set forth in connection with apparatus having a particular constructiton and arrangement oi parts and mode of operation, it will be seen that various changes and modications may bemade therein, while securing to y a greater or less extent some or all of the beneitsof the invention, without departing from the spirit and scope thereof.

I claim:

l. In a cracking process wherein vapors at a cracking temperature continuously flow from a reaction chamber through a vapor outlet line in immediate communication with the reaction.

chamber and wherein-such now of vapors is continued for an extended period of time, the method of removing coke deposits'and maintaining' the free flow of vapors from the reaction chamber through the vapor outlet line which comprises normally permitting the flow of vapors through the entrance to the vapor outlet line without the application of any cooling fluid at said entrance, at intervals vforcing a plunger element through lthe vapor outlet line thence into the reaction chamber to thereby dislodge coke' formations in the path thereof, as the plunger passes through the vapor outlet line directing a uid medium against the inner wall thereof with sucient force to wash awayicoke formations,

v.to'thereb-y dislodge coke formations in the path thereof, and at such intervals directing a vviiuid' medium against .the inner wall of the vapor out-1k let line and against that portionfof the'rwall lof the reaction .chamber adjacent the entrance' to and when the plunger is within the reaction rection through a vapor conduit and wherein' such flow of vapors is continued for an extended reaction chamber to thereby dislodge coke formations in .the path thereof, as the plunger passeszthrough the vapor riser directing a huidY medium-against the inner wall thereof with sufficient force to' washaway col/:e formations, and whenthe plunger is within the reaction chamber directing a fluid medium against that portion of thev wall of the reaction chamber and wherein such flow of vapors is continued for an extended period'oftime, the meth-Y od of removing coke deposits and maintaining the free flow of vapors from the reaction chamberthrough rthe vapor outlet linewhich com-' prises normally permitting the ilo'w of r,vapors through the entrance to the vapor'outlet line .without the application of any cooling fluid at said entrance, at intervals of the order of once or twice a day forcing a plunger elemerit through the vapor line thence into the reaction chamber the vapor outlet line: with suific'ient: force to wash away coke formations.

4. In a cracking process whereinvapors-at a cracking temperature flow continuously from a inn an Y upward direction through a vaporriser and flow thenceL in a horizontal directionvr through a vapor conduit and wherein such iiow of vaporsvis continued for an extendedperiod of-time, the method of removing coke deposits and maintaining thejfree iow of vaporsvfrom the reaction chamber, through ther period of time, the method of removing coke de- 1 vapor lines which comprises-*continuously intro- A, ducing a cooling medium into the streamv of va-` pors flowing in the. horizontal directionwhle y normally permitting the iiowof vaporsthrough Y Y the entrance to the vapor riser-without the apf-v plication yof any cojoling fluid atsaidentrance',

at intervals ofthe orderof once `or twice a day forcing a plunger element downwardly 'through the vapor riser thenceinto the reaction chamber to thereby dislodge cokeformations inthepath thereof, at such intervals directing a fluid-medium against the'inner wall of the vapor outlet line and againstthat portion of the wall of the g reaction chamber adjacent the entrance to the. vapor outlet line with sufficient force to wash away coke formations, andlimitingthe application of such fluid medium at said 'intervals to a period of time of theorder of 1-.3 minutes.

ROY J.: DIWOKY.

fOlCIlg a plunger lelement downwardiyithrough the vapor riser thence into the reaction chamber

Images