US1677772A - Art of cracking hydrocarbons - Google Patents

Description

July 17, '1928.

E. c. HERTHEL ET AL .ART oF CRAEKING HYDROCARBQN'S Filed Juney 22, 1926 2 Sheets-sheet Xb .Nimm

INVENTOR t M# n m, M/C, N fd. R E To gm. J Cm A E gag Patented July 17,i1192 8 a -i-fuNiTEo STATES' PATENT CFFICE EUGENE o.. nnn'rnni. AND THOMAS DE COLON rirrfr, "or onioaeo, ILLINOIS, As-

sIGNoRs ro SINCLAIR REFINING' contr-ANY, or NEW YORK, N. Y., A CORPOBaTION F MAINE. i .i

ART OF CRACKING GABVONS.

Application filed June 22, 1926. Serial Noi 117,696.

Our inventio'h'vcornprises an im roved ydroi carbon loils, such for example asgas oil, fuel oil, and topped crude oil, to produce theremethod of treating higherboiling for example as gasoline' and pressure distillate.

In carrying out the process of our invention, the 'fresh higher boiling hydrocarbon oil to be treated is forced in a single pass through a heatingzone in heat exchange with heating gases, such as the hot products of combustion from a furnace in which fuel is` burned, by Whichit is heated to a crackingy 1'5 temperature and is then discharged into a vaporizing zone, being maintained under a superatmospheric pressurepin'both `the heat- In this vaporizing zone` a part of the oil includinging zone -and the 'vaporizingzone vapors'of the desired lower boiling hydrocarbon -oils is separated from the unvaporrized components of the oil discharged from the heating zone-and these vapors are taken off and subjected to ap ropriate treatment for the separation of t e desiredfraction be mass remains. The vapori'zation in the second -,or fractions; Theyyniay, f or example,

j subjected to a refiuxingpopei'ation for the separation o'f heavier componentswhich heavier components may again be -passed so through the heating zone, the vapdr s escaping from the reuxing operation being subjected to condensation to form ajpressnredis- The unvaporized oil collecting inr this vaporizing zone, the primary vaporizing zone` .is Withdrawnas a liquid therefrom and discharged Ainto ay secondary vvaporiziniz` zone 1 tillate.

which is maintained under a pressure' lower than thatiprevaili'nig inthe primary vaporizing zone. Due tothe reduction in pressure,

40 a-further separation o f vapors is effec/ted in fthe secondary vapori'zing zone andf-these vapors are taken O ii' and condensed foi-ming a condensate heavier than that produced from-.the vapors separated inthe primary The unvfaporized' residue resulting from the secondary vaporizing operation is not returned'to the heating. zone., The condensate formed from the vapors separated from the secondary vaporizing zone,

D however', is returned, in Whole or in part, to

the heating zone, being forced therethrough' first in heat exchange with the heating gasesl before they are brought into heat exchange with the fresh oil and then 4being vangiiiired vlaporizing zone.

with. the yfresh ou and passed through the heating fzohe therewith 'in heat exchange with th'e'heating gases tempered by the abs oiptionA of heat therefrom in this conden 5 'from lower boiling hydrocarbon oils, such sate Where the heating gases are first brought into heat exchange With it. Y v

In carrying out the invention', itfis advantageous to take' ofi" ais.' vapors from ther i primary ivaporizing zione, or, if these ,vapors are subjected to a reiiuxing operation, as' vapors from the refluxing Ope1at1on,a re,

stricted proportion ofthe oilg say not Amore-4 than 40 to 45% or better about 35% of the oil forced into thevaporizing haniber,;-

exclusive of reflux. In thesecond Vaporizing zone, the unvaporized oil is' subjected to further vaporization'by reduction in pr'es-v sure, advantageously by means of its self-` contained heat,A and in this second va or1zing zone as muchas 80% `or, more of t ie oil may be separated as vapors/,g vVaporization vin the second vaporizing zoneinay be carried vaporizating zone can be controlled by regu* lation of the dpressure therein. The condensate produce from Athe vapors separated in the second vaporizing zone is relatively re- Y fractory ,towards further cracking, as comconditions while at the saine time it is With advantage employedto ltemper lthe heating gases supplying heat to the operation before they are brought in heat exchange with the fresh oil to prevent overheating or Overcracking. Theheat absorbed in this refractory oil, in carrying out this invention, is employed in kan advantageous Way to crack this voil With the production of further, quantities of the desired lower boiling hydrocarbonsv andalso, when tliisoil is adrnixed With the fresh oil, to assist in heating the fresh oil. v Y

The heating Operation may, for example,

pared to fresli'oil, and it therefore is with advantage subjected to more severe cracking be carried out in a pipe or tube stilll arranged so that condensate from the second-- ary vaporizing operation is circulated `first through one battery of pipes or tubes therein and then through a second battery and so that fresh oil is supplied at an intermediate point being passed only through the second battery of tubes in admixture with 4the 'condensate from the vapors produced in thesecondary raporizing operation, heating gases being` passed first over the battery of tubes through which this condensate 1s circulated alone and then through the Abatulated and reduced between the two vaporizing drums by afmanually or automatically controlled pressure, reducing valve. This valve may be arranged to operate to maintain a, fixed liquid level in the primary vaporizbing drum. This secondary vaporizing drum is advantageously externally unhe'ated i vand llagged .or' insulated to pr'event heat loss so. that the secondary vapor-ization is effectedby heat contained in the unvaporized oil from the primaryvaporizing drum'.

I vaporiziug drum is carried' to the point,

out in apparat-us of the type diagrammatilVhere the vaporization in the secondary where coke or acoky mass remains, duplicate vaporizing receptacles may befprovided so that the operation can be carried out in a continuous manner. A

Fig. 1 of the accompanying drawings illustrates pictorially the operation of the process of our invention. le will further describe the invention by reference to an operation in accordance therewith carried cally illustrated in Fig. 2.

y Referring to Fig. 2, fresh oil is forced from connection 3 through the tubes 4 in -the heating furnace 33 and is discharged therefrom through connection 5 into drum- G. In the heating furnace 33, heating gases from the fire'box 34 pass first over the tubesl 35 andthenI over the tubes 4;. To promote the efliciency of the heating furnace, part4 of the vheating' gases may be withdrawn from a point near the outlet to the exit flue 'and returned and adrnixed with the fresh heating gases from the fire box, as the steam Jet blower A'i'. illustrated. Oil supplied through connection 36 is forced through th'e heating tube 35 and then inv admixture with fresh oil supplied through connection -thioughV the heating tubes 4 and into the, drum 6.

I The oil may bebrought, for example, toa

ltemperature between 750 and 950.0 F. 1n

the heating furnace and discharged into the drum 6at approximately this,` temperature. The `mixed vapors and liquid from the heating furnace ma be discharged into a liquid body of oilvvit inthe'drum 6 through connections such as shown at 8, orv this `mixture sulated to prevent vheat loss'.

may simplybe discharged into the upper .part of the drum. The pressure maintained on the drum may be as much as 100 to 200 pound per square inch or more. This pressure may be maintained by appropriate regulating valves located in the discharge lines, may be regulated, for example, by a valve 9 between the vaporizing'drum and the reflux condenser' 10 or by a valve ll bctween the reflux 'condenser and the final condenser l2 or by a valve l beyond the final condenser'. A connection is provided al,v lit for initially supplying a charge ol oil to the drum 6 orfor removing residue therefrom. Additional heavy oil may also be supplied to the drum through this connection during the operation to be cracked inl thedrum. Additional external heat may be supplied to this drum as by the furnace 17 illustrated, or the drum and its contents can be heated internally only by the mixture discharged into the druml from the heater. 1

yThe drumniay with advantage, particularly in the' lattertype of operation, be lagged or insulated to preventheat loss.

`The vapors separated in the drum A6l vescape therefromth'rough connection 15' to 'l the reflux tower 10. From'the reflux tower','

the remaining uncondensed vapors includ-` ing the vapors of the lighter hydrocarbon oils to be produced escape through conne tion I6 to the condenser 12. 'Cool fresh oil l is introducedthrou'gh 'connection 18 into'direct" contact with the' .vaporsV passing through the reflux tower.

by regulating the proportion `of cool oil so introduced, and to facilitate such control the The refluxing. 'operation can be controlled with advantage reflux tower is advantageouslyl lagged or insulated toI prevent heat loss.l The reflux produced in the tower admixed with the un vaporized part of the fresh oil introduced .into the tower, which fresh oil is heatedby contact Withthe vapors in .the tower, passes through connection 19 to the reservoir 20.

To promote elliciency, this connection and the reservoir 20 may also`be lagged or iny This mixture, advantageously all of it, is withdrawn from reservoir 20 and forced through the tubes 4 in the heating furnace by means of pump 21.

The unvaporized liquid oil collecting in vthedrum 6 1s dischar ed therefrom through connection 22 intot e drum 23 which is maintained under alow'er pressure than that prevailing'in drum 6, `the pressure onv the secondl drum being reduced and regulated by a .valve 24 in connection 22. This drum 23is lagged or insulated to prevent heat loss and the oil discharged into thisl drumfroml drum 6 is partly vaporized therein by its self-contained heat due to the reduction in pressure. VThe unvaporized residue collecting` .separated in drum 23 esca 'ef through conconnection 25', or if 'solidi-in nature, is removed'through. outlet 26 lThel vapors nection 27 to condenser 2 8 om whichcondensate is discharged into reservoir 29l The pressure` Within4 drum 23 may be substantially atmospheric' pressure or"l a, somewhat' higher pressure, and the extent to `Which vaporizationv is effected therein can be con'- Atroll'ed,i with. advantage, by regulating the pressure maintained therein. By eso regulating the pressure, substantiallyany desired proportion of'the liquid residue Pdischarged into drum'23 from drum 26 can be j vaporized to leave either la liquidresidue or Va solid or semi-solidresidue in drum 23.

In somel cases, aupressur'esomewhat below;

. atmospheric pressure may be maintained in drum 23, as by suitably arranging the -co'ndenser 28. The vpressure in drum 23,-,ac--

cordingly, may range from somewhat' below 'atmospheric pressure up to as mueh as 25' orf() pounds per square inch or more. Vaporization may .also be promoted` byinjecting steam vinto the' secondary vaporizing zone. f

'Fresh oil is supplied tothe operation from reservoir 30 lay-means 'of 'pun1p-31.' Gouden-v' sate collecting in reservoir 29 is returned to the operation by. means' o'fpump 32, being forced first throughthe tubes 35. in the heatingfuriia'ce and then through the tubes 4 in admixture with fresh oil, and reflux'. The operatien may with advantage Abe controlled 'Y as by regulating the'refluxing operation, so

' that the pressure .distillate takenof through connection 16 amounts tog'not more than 40 to or Ybetter 35%, of the oil supplied from the reservoirs 29 vand 30. In the heat-V ing furnace 33, the. heatinggases lfrom the fire box 34 pass first over the 4tubes 35k and then over the tubes 4,'So that the condensate produced from the 'vapors separated in the secondary vaporizing drum is irst brought into heat exchange with the heating gases While they are at highest temperature thereby subjecting this oil to 'the most severe conditions, prevailing in the heating furnace and at the same time tempering the heating gases by the absorption of part 'of their heat in this oil. In the tubes 4, the fresh oil isA thus subjected to less severe conditions and is less liable to be overheatedor overcracked,

the tubesthrough which the fesh oil is cir-v culating similarly being protected byV this tempering of the heating gases.v The -eil diss' charged from the tubesv 35 also assist in heating the fresh oil .in the tubes 4 by direct heat exchange therewith reducing to this eX- tent the amount of heat necessary to be tranferred through these heating tubes. If, instead of asin-the apparatus illust-rated Where the fresh oil, or art of it, is introduced into direct contact with the va ors from the primary vaporizingfzone in t e refluxing oper- Ymeans of cooling, therefluntherefronipar- .,ticularly Where it a}).proach es in character` the condensate produced from the'vaporiaaation to which they-are subjected, this re- ,i fluXing. operation is'effected by some other,A

tion from the secondaryv vaporizing; Zone,

may be admixed with this condensate and returned l'through vthe heater in admixture therewith instead of in admixturelitvith the fresh oil. -To `promote efficiency, Athe .condensateV collecting in reservoir 29 may be cooled only sufficiently to .permit it to be handled by a pump so -that it" canbe forced through the. heater into the vaporizing drinn. i

In the operation lof a battery of pressure stills for producing lower -boiling hydrocarbon oils from higher boiling hydrocarbon oils, a single secondary vaporizing receptacle mayy becusedto handle the'unvaporizehd oil residue from'several rimary vaporizing'receptacles, or the con ensate produced from the vapors from one or more such secondary .va'porizing operationsmight b e collected in the ycommon -receptacle from whlch various :stills inthe batteryor group might be supplied.,A f

, -The important advantages. The period of operation, in accordance with the invention, is materially prolonged by several-factors and important operating economies are thereby secured; e In the heating furnace,the tubesA exposed to the heating gases at highest temperature vare protected by circulating therethrough 'a relatively refractory oil all of which has once been vaporized and yvhich is substantially free Afrom pitch or pitch-like constituents, and the heating tubes through which more easily cracked oil is circulatedA are' protected by the temperingl ofthe heating rgases effected by passingt em first over the `heating tubes through which the refractory' oil is circulated. `Although the proportion of pressure distillate removed may be relatively restricted, the oil remaining unvaporized, although a preponderating part of the charging stock, is so handled as to effectin an advantageous Way a separation of, all pitchy or coky constituents which mi ht otherwise interfere with the operation if t is process of our invention has several lio unvaporized oil were directly 'returned to the 'p heating operation, so. that the greater porpassed through the heating operation and which might interfere with the operation if l returned thereto are prevented from again I boiling hydrocarbon oils from higher' entering the lheating zone. In many cases,

thiscombined operation. enables the production of pressure distillate and of thevdesired lower boilinghydrooarbon oils to be-in.

creased by increasing the amount of stock of pressure distillate removed. In any event,

'the efficiency ofthe operation "is improved by prolonging the period over Which' the operation can be carried out before it is necessary for4 il'is'peotionl orl cleaning.

We claim: y l An improved method of producingb lower oiling hydrocar on oils, which comprises forcing Such higher boiling hydrocarbon oils in a single pass through `a` heating zone into a primary vaporizing zone and. maintaining the loil under superatmospheric pressure in both the said-heating zonfe and the primary v to sliut downthe apparatus .employed Ipassing heating gases in the heating zone vaporizing zone, passing unvaporized oil -these vapors again through the heating zone,-

irst in advance of fresh oil and then in admixture with fresh oil, Without returning to ,the heating zone unvaporized components of oil ivhich have once-passed therethrough,

rst in heat exchange with the 'oil condensed from vapors from the secondary vaporizing zone and ,then in heat exchange with the mixture of this oil with fresh oil, and taking off vapors from the primaryvaporizing zoneincluding vapors ofthe desired lower boiling hydrocarbonoils.

` EUGENE() HERTHEL.

THOMAS DE COLON TIFFT.

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