US2326186A

US2326186A - Conversion of hydrocarbons

Info

Publication number: US2326186A
Application number: US394979A
Authority: US
Inventors: Claude W Watson
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1941-05-24
Filing date: 1941-05-24
Publication date: 1943-08-10
Anticipated expiration: 1960-08-10

Description

Aug i0, W43., c; W, wATsoN CONVERSION oF HYDRocARBoNs Filed May 24; 1941 N Iv w 5 T. R Y Y Q. m3 WH m M W N \Luu-.:n 5 m. N l Uo/T U 4. A a

M, wmv JM Nm w Inv E um@ Nw r w mlm J N among, :Je \\.mm

Ow mi crude in a heated condition directly from the topping or reducing stills and a line 2l is indicated for so introducing the hot residue.

The tarry condensate obtanedrin'thedephlegmating section I3 from the primary dephlegmation of the vapors from the coking drum B may be withdrawn as a liquid fuel product condensate and unvaporized residue withdrawn through line 22 and passed through a branch line 25 into the line 23. rlhe pump 24 directs the oil, as withdrawn either from section i3 or from trapout tray IB, through a line 26 to a heating coil 21 disposed in a furnace 28 and the heated products pass through a transfer line 29 to the reaction chamber A.

In some cases the heating of the heavy oil in the coil 21 may be omitted and the oil by-passed through a line 30 directly to the transfer line 29 thence to the reaction chamber A.

Vapors uncondensed in the tower C pass through a line 3l to the fractionator D wherein lin the' coil' I8 and the heated residuum introduced into the tower C. Constituents of the nature of kerosene and gas oil are distilled off the residue in the tower C and passed to the tower D tothe vapors are fractionated to separate higher boiling refluxcondensate from lighter vapors and gases. `'Ihe reux condensate is withdrawn by a pump 32 and directed through a line 33 to a heating coil 34 disposed in a furnace y35 and the heated products are passed through a transfer line 3G to the reaction chamber A or to the transfer line 29 so as to combine the heated products with the heavy oil stock being delivered from the heating coil 21 or from the by-pass line 30 A Uncondensed vapors from the tower D pass to a condenser 31 and the distillate is collected in a receiving drum or gas separator 38.V The drum 38 is maintained under superatmospheric pressure and normally gaseous hydrocarbons, predominantly methane and C2 hydrocarbons, aswell as hydrogen, are removed through a gas line 33 while the gasoline or naphtha distillate containing normally gaseous hydrocarbons. predominantly C3 and C4 hydrocarbons, is collected as a liquid in the drum. The liquid distillate is withdrawn by a pump 40 and conducted through a line 4| to a rectifying tower 42 wherein the distillate is subjected to rectification. or stabilization to remove normally gaseous hydrocarbons and the rectified product is withdrawn through a line 43. The uncondensed gases passte a condenser 44 thence to a receiving drum 45 having a gas outlet 45. The liquid distillate inthe drum 45 comprising predominantly C3 and C4 hydrocarbons is withdrawn by a pump 41 and directed through a line 48 to a heating coil 49disposed in a furnace 50. The heated products pass through a transfer line 5l to the reaction chamber orftransfer line 29 so that the heated products may be combined with the other products undergoing reaction in reaction chamber A. The normally gaseousjhydrocarbons being passed` through the coil 49 may be subjected to temperature pressure conditions therein adequate to effect polymerization into liquid hydrocarbons. In an alternative operation the normally gaseous hydrocarbons may be merely preheated in coil 49 and then directed through a branch line 52.1or combining with the cycle condensate being passed through the heating coil 34 wherein the mixture yof normally liquid and normally gaseous hydrocarbons is subjected drocarbons.

gether with cracked constituents from which tower the reflux condensate is cycled to the cracking or conversion coil 34. The gasoline distillate is collected in the receiver 33 and the gasoline is stabilized in the tower 42 under superatmospheric pressure. The overhead from the tower which collects in receiver 45 consists essentially of the heavier of the normally gaseous hydrocarbons, more particularly C3 and C4 hy- A portion of the distillate collecting in the receiver 45 is normally employed for refluxing the tower 42 and the remainder is directed to the coil 49 wherein it is subjected to polymerizing temperatures such as temperatures of the order of 900 F. and 1000 F. under pressures of the order of 500 to 1000 lbs. land the resultant products of conversion are directed to the reaction chamber A for further reaction with the other hydrocarbons therein. If it is not desired to subject the C304 fractions to separate polymerization the coil 49 may be used as a preheating coil and the preheated normally gaseous hydrocarbons combined with the reflux condensate passing from the tower D to the conversion coil 34. In somey cases it is advantageous to subject the normally gaseous hydrocarbons in the coil 49 to high temperatures of the order 'of 1000 to 1200 F. to eiiect an increase in the olein content thereof and combine the resultant products of conversion with the cyclecondensate in the coil 34. In the coil 34 the mixture of normally liquid hydrocarbons and normally gaseous hydrocarbons is subjected to temperatures of the order of 900 F. or 1000 F. under pressures such as 400 to 800 lbs. to effect cracking and reversion reactions and to concomitantly effect conversion of higher boiling normally liquid hydrocarbons into lower boiling products and conversion of normally gaseous hydrocarbons into higher boiling hydrocarbons within the gasoline boiling range. The products of conversion are combined with the black oil introduced directly from the tower C through line 30 or after heating in the coil 21 for further reaction in the reaction chamber A. d

It is advantageous to subject the topped or reduced crude to viscosity breaking in the coil i8 before introducing to the tower C. In such anY operation the heating in the coil 21o-f the mixture of unvaporzed residuum Vand reflux condensate which is drawn from the tower C may generally be omitted and the mixture may be cornbined directly with the hot products from the reversion coil 34 or with the hot products from both

heating coils

34 and 49. When employing the coil 21 the black oil stock is subjected to cracking or viscosity breaking therein under temperatures of the order of 800 F. or 900 li. and under pressures such as 200 to 600 lbs.

The reaction chamber A should be maintained under pressures at leastas yhigh as about 200 lbs. and preferably under pressures of the order of 300 to 600 lbs. It is desirable to maintain somewhat high pressures in the tower A in order to promote continued reactions of the nature of aseo-,iso

It is preferred to maintain in the reaction cham`V bei" A as high a temperature as is possible without cokrrg and this temperature will ordinarily be in the neighborhmciof 900 *Et-930 F. Liquid is prevented from accumulating in the chamber A by the rapid Vwithdrawal of the liquid residue through the line- M; While a single down-flow reaction chamber has been ilhistrated it is to be' understood that the reaction zone in which the commi-'ngled products from the heating coils are subjected to reaction may' assu-me various forms. For example, it is advantageousto provide an initial downiiow reaction chamber with all of the products, both vapors and liquid, passing together without separation into a subsequent upflow' reaction chamber fro-rn whichvvapors are at the top and a mixture of vapors and liquid residue withdrawn fromI the bottom for* passage to the eoking drum". Another advantageous arrangement is to provi-de a counterflow` reaction chamber with the black oil stream bei-ng introduced' to an upper portion and the stream from heater 342 being admittedl to a lower portion of the chamber.

The temperature required for colring depends on the pressure and character ofthe stock introduced into) the ocking drum- In general a temperature in excess or 825i" is required: in order to eil'ectl colti-ng tot" the production ol' a marketable cuire: and the temperaturesused` will ordinarily* be about 840i F. to 85F A temperatute, for example; of 860' E'. under pressures of 1154-! FZ lbs. in the coburg' drum is quite satisfactory; Tis-ie passage material.' trom the reaction mating the coking drum pressure A. .relatively small amount' of cooling applied. to the de'- phlegmator it, as by theirrtroduction. of a small amount o1 cycle condensate, in orderto prevent cokmg in the dephl'egmator. When running to coke only the temperature in the dephlegmator may be Vmaintained vwithout coking at a somewhat higher range than when ,drawing a fuel oil` productffzsom the dephlegrnator. Thus, for example,- in tlfxey coke onlygoperation temperatures of around 810 il.` to 820 F. may be maintained inthe dephlegm-ator and when running to coke and fuel oil temperatures of about '290 F. to 800 may be maintained.. When running to coke and distillate hiel` oilthe mixture of. uniza-` porzcd residuum and reflux "condensate may be withdrawn from the tray I6 at tempera-tures approximately 800 F. The top ot the tower C may A be maintained at. temperatures approximating chamber A through. the lino t0* to the `coking drum E is controlled so to. continuously' pass of the liquid; together with a. sumcient. portion of the` vapors to maititam the desired aching temperature the coking without causing priming through. the vapor line or the. ooking drurm A relativelysnrallz ptomirdon of the val e required. for this: purpose. a proportion vapors leaving the reaction chamber. By operating inthis manner itfis possible to obtain? charging rates' and recycling ratos.: that is,. rates oi tor` the' cycle condensate andV `recycle gases for the: black ol@, oit an extremely high magnitude; which igtv has7 been impossibleito reach in priori methods ot, operation. For example; on equipment in which therlintit in' the gas oil Ife-v cycling ratelv was within. thzerange of 230v to 280 bbls. per hour order toavoid` priming, in the coliiog the prac-tice ot the irrnfentiorr maires may be obtained;

The iractionating towers C and D are advantageously maintained under pressures approximately' the orderV of 10% of` the; total 710 F. to 'I300 F. under about 150 lbs` pressure andthe bottom of tower D may be held. at temperatures around 66061, to 690 F;

Y In general the higher the pressure applied. in the coking drum the greater will be the yield off coke and when running to coke and distillate fuel. oil Athe higher the pressure vthe greater the ratio of coke to fuell oilr The pressure carried in the cokng drum may accordingly be varied somewhat. in accordance with the requirements for colte` and fuel oil., It is desirable however. toY maintain sufficient pressure in the coking, drumf tru-'insure the proper separation inV the rcoeivingdrum 3B. In other. words, in order to obtain the desired retention of C3. and C); hydro#` carbons in` the distillate withdrawn` from the receiver 38' it is desirable that the pressure should he at least as high. as 1.00 lbs. and preferably V1.50 lbs. or more. When the coking opera.- ti'on is carried on under low pressure such as 50 lbs. it may be desirable to subject. the gases passing through` the line 39 to additional fractionation or absorption norder to :recoverV C3 and C4. hydrocarbons thereirorn. In an alternative method of. operation the towers C and D are maintained under pressures approximating Vthe pressure in the. reaction chamber A. and under measures of 200 lbs. or higher which insuresl a very good separation in .the receiver 3S, while the coking drum is operated under desired low pressure such` as around lbsr and. the vapors from the coking. drum are separately corrdensed and.. the distillate reuxed on either or vboth of the..towers C and D.

While I. have described a particular embodiment of my invention for purposes. of. illustra tioru. it shouldv be understood. that variousy modicatons and adaptatif;ns4 thereof which will be obvious to one skiliedin the art, may be made within the spirit; of. theY invention. as set forth in the appended claimst 1.-. In the conversion of hydrocarbons for the production of gasoline., the process that comprises. subjecting a mixture of cycle condensate and normally gaseoushydrocarbons to conversionV ternp@ratureA ina conversion` zone to effect conversioi/.i into gasoline constituents, combining the resul-tant products of conversion. with resi-'ie ual constituents of crude petroleum for reaction in a reaction zone maintained: at` cracking temperature under superatrnospheric pressure and wherein separation of vapors from liquid residue takes place, preventing the accumulation of liquid in said reaction zone by rapidly withdraw- Y ing the liquid residue, including a portion of the vapors with the vliquid residue Ythus Awithdrawn from the reaction vzonein quantity` sufficient to eifect the autogenous coking thereof and delivering the mixture to a coking Zone maintained under. reduced pressure wherein coking takes place'wi'thout priming, separately withdrawing vapors from said reaction zone, subjecting evolved vapors from the coking zone' and separated vapors fromthe reaction zone to'fra'ctionation to separate va condensate from heavier and lighter constituents, cycling said condensate to theV aforesaid,conversionV zone, subjecting said lighter constituents to further fractionation toV separate normally liquid hydrocarbons from normally gaseous hydrocarbons comprisingCs and C4 hydrocarbons and cycling such normally gaseous hydrocarbons to said conversion Zone. 2. In the conversion ofV hydrocarbons for the production of gasoline, the process that comprises subjecting a mixture ofv cycle condensate and'normally gaseous hydrocarbons to conversion temperature in a conversion zone to effect conversion into gasoline constituents, combining the resultant products of conversion with hydrocarbon oil as hereinafter specied for reaction in a reaction zone maintained at cracking temperature under superatmospheric pressure and wherein separation ofvapors from liquid residue takes place. preventing the` accumulation of liquid in said reaction zone by rapidly withdrawing the liquid residue, including a portion o the vapors with the liquid residue thus withdrawn from the reaction zone in quantity suicient to eiTect the autogenous coking thereof and delivering the mixture to a coking zone maintained under reduced pressure wherein coking takes place without priming, separately withdrawing vapors from said reaction zione, dephlegmating evolved vapors from the coking zone and separated vapors iromithe reaction zone with a crude petroleum residual stock to produce a mixture of residual stock and heavy reflux condensate, utilizing said mixture as the hydrocarbon oil being combined with the products from said conversion zone for reactionV in said reaction zone, subjecting the dephlegmated vapors to further fractionation to separate reflux condensate from lower boiling hydrocarbons, cycling said reux condensate to said conversion Zone, subjecting the separated lower boiling hydrocarbons to further fractionation to separate normally liquid hydrocarbons from normally gaseous hydrocarbons comprisingCg and C4 hydrocarbons and cycling such normally gaseous hydrocarbons to said conversion zone. Y Y 3. In the conversion of hydrocarbons for the production of gasoline, the process that comprises subjectingja mixture of cycle'condensate and normally gaseous hydrocarbons to conversion temperature in a conversion zone to effect conversion into gasoline constituents, combining the resultant products of conversion with hydrocarbon oil as hereinafter specified for reaction in a reactionzone maintained at cracking temperature under superatmospheric pressure and from the reaction zone in quantity suicient to effect the autogenous coking thereof and deliverng the mixture to a coking zone maintained under reduced pressure wherein coking takes place without priming, separately withdrawing vapors from said reaction zone, dephlegmating evolved vapors from the coking zone in a dephlegmating zone to form a heavy tarry condensate, passing the dephlegmated vapors to a second dephlegmating zone, directing separated vapors from said reaction zone to the second dephlegmating zone and dephlegmating the vapors therein with aV petroleum residual stock,

utilizing the resultant mixture of residual stock and heavy reiiux condensate as the hydrocarbon oil being combined with the products from said conversion zone for reaction in said reaction zone, subjecting the latter dephlegmated vapors to further fractionation to separate reflux condensate from lower boiling hydrocarbons, cycling said reflux condensate to the aforesaid conversion zone, subjecting said lower boiling hydrocarbons to further fractionation to separate normally liquid hydrocarbons from normally gaseous hydrocarbons comprising C3 and C4 hydrocarbons and cycling such normally gaseous hydrocarbons to said conversion zone.

4. In the conversion of hydrocarbons for the production of gasoline, the process that comprises subjecting cycle condensate formed as hereinafterspecified to conversion temperature under superatmospheric pressure in a conversion zone to effect conversion into gasoline constituents, combining the resultant products of conversion with hydrocarbon oil as hereinafter speciiied for reaction in a reaction zone maintained at cracking'temperature under superatmospheric pressure and wherein separation of vapors from liquid residue takes place, preventing the accumulation of liquid in said reaction zone by rapidly withdrawing the liquid residue, including a portion of the vapors with the liquid residue thus withdrawn from the reaction zone in quantity sufficient to effect the autogenous coking thereof and delivering the mixture to a coking zone maintained under reduced pressure wherein coking takes place without priming, separately withdrawing vapors from said reaction zone, dephlegmating evolved vapors from the coking zone and separated vapors from the reaction zone with a petroleum residual stock to produce a mixture of residual stock and heavy reflux condensate, utilizing said mixture as the hydrocarbon oil being combined with products from the conversion zone `for `reaction in the reaction zone, subjecting the dephlegmated va'- pors to furtherfractionation to separate reflux condensate from lower boiling hydrocarbons, directing said reflux condensate to said conversion Zone, subjecting said lower boiling hydrocarbons to further fractionation to separate normally liquid hydrocarbons from normally gaseous hydrocarbons comprising C3 and C4 hydrocarbons, subjecting said normally gaseous hydrocarbons to conversion temperature under superatmospheric pressure to eiect conversion into higher boiling constituents within the gasoline boiling range and directing the resultant products of the latter conversionV to l`s aid reaction zone.

' CLAUDE W. WATSON.