US2316931A - Continuous process for cracking and polymerizing petroleum oils - Google Patents

Description

April 20,1943.

D. G. BRANDT CONTINUOUS PROCESS FOR CRACKING AD POLYMERIZING PETROLUM OILS Filed May 14, 1940 a ina madam.

Patented Apr. 20, 1943 CONTINUOUS PROCESS FOR CRACKING AND POLYMERIZIN G PETROLEUM OILS David G. Brandt, Westfield, N. J., assignor to Cities Service Oil Company, New York, N. Y., a corporation of Pennsylvania Application May 14, 1940, lSerial No. 335,059

(Cl. 19d-58) 12 Claims.

This invention relates to a continuous process for cracking and polymerizing petroleum oils by subjecting heavy residual types oils to high temperature and pressure conditions adapted to crack portions of the oil to produce gasoline, and polymerize other portions to produce a stock of high specic gravity suitable for the production of petroleum coke.

Many cracking processes produce both high and lower molecular weight hydrocarbons from the charging stock, and many coking processes have been developed for coking cracking still resduums. Some combined cracking and coking processes have been developed in which the charging stock heated in a pipe still furnace is alleged to be converted into vapors and a nonlowing carbon residue, the latter of which is collected in an enlarged coke chamber. In many of the cracking operations in which coke is produced from petroleum oil, the coke is mostly of low marketable quality, and in such processes there seems to be no consistent elort to control the quality of the coke either from the standpoint of its marketability or from the standpoint of producing a coke which can be removed from the coking chamber in a satisfactory mannez. Efforts directed to the control of the cracking operation have been largely toward increasing the quality or quantity of the gasoline produced.

The primary object therefore of the present iivention is to provide an -improvednprocess for cracking and polymerizing residual petroleum oil stocks `to produce a hydrocarbon stock of high specific gravity which can be converted into a marketable coke.

A further object of the invention is to provide an improved continuous process for simultaneously producing gasoline and a petroleum -tar or pitch of high specic gravity which is converted into marketable petroleum coke.

A still further object of the present invention is to provide an improved polymerization and cracking process for converting residual `petroleum stocks into gasoline and a residue of,high specific gravity suitable for coking, in which the various features of the process are correlated to produce ylighter oils and marketable coke from the stock, with of course the incidental production of some'gas. Y

Accordingly, the improved process of the supera-tmospheric rosive, to prevent corrosion in the apparatus), through a heating zone comprising a heat eX- changer coil mounted in a fractionating tower wherein the charging stock is heated in indirect heat exchange with vapors produced in the conversion operation, preheating the charging stock to a temperature of approximately 650 F., and subjecting it to pressure cracking and polymerization conditions in an enlarged chamber wherein the stock mixture is lpassed in intimate contact with high temperature vapors produced in `another part of the operation to heat the stock fora substantial period of time to a temperature above 800 F., maintaining a body of the stock in the lower portion of the enlarged chamber to increase the time reaction, cracking and polymerization .of stock to produce a residuum having an A. P. I. lgravity of from about 2 to 15, conducting the high temperature vapors, after contact with said stock, on through said enlarged `chamber and then into the lower portion of said fractionating tower wherein they Vare subjected to rectification to produce a .reflux distillate of high `boiling point and the desired lower boiling products, passing a portion of the lreflux distillate from said Vfractionating tower into the upper part of said enlarged chamberin intimate Contact With the high temperature vapors passing therethrough, conducting `another portion of the reflux distillate from said fractionating tower through a pipe still furnace Vand therein heating the `same kto a high conversion temperature at a substantial pressure, .conducting the highly ,heated 4products from said pipe still furnace through v.a transfer .line and mixing therewith hot heavy liquid oil residue from the lower portion of said .enlarged chamber to intimately contact said Products, thereafter conducting the resulting mixture into the upper Aporition of one of a plurality of alternate enlarged coking chambers, separating vapors from unvaporized oil constituents including said residue .in said coking Chamber and vconducting Vthe vapors at a high temperature into the lower portion of said enlarged chamber for` effecting said cracking vand polymerizing operation, retaining the unvaporized liquid oil residue ,in said ycoking chamberto be .converted into coke, land removing .the vapors from the upper portion 0f Said fractionating tower and recovering the gasoline constituents ,therefrom- `,Other :featuresand objects of the present 1n- .vention :will he :apparent t0 those .Skilled in the art. imm the iollowixiemcre detailed descrip-A ducted from a charge supply tank 2 through a line 4, and forced by means of a pump therein,

through a heat exchange coil S-mountedinandextending through a fractionating tower 8. If

the charging stock contains suicient sulfur or other corrosive materials to cause' excessive cor-Y rosion of the apparatus, a small portion of lime may be conveniently introduced into the line 4 l by a line I as a slurry in some of the charging stock. This lime slurry is preferably made up, in

suitable apparatus, not shown, by mixing a predetermined proportion of Vhydrated lime with a definite proportion of the charging stock. v,

The fractionating tower 8 is preferably of the usual bubbler type construction with the convolutions of the coil 8 mounted in the vapor rspace above the bubbler trays. `The tower is preferably operated at a pressure of about 225 lbs. per square inch to condense all of the oil constituents produced in the cracking operation, of higher boiling point than the desired gasoline or pressure distillate product, which is removed overhead in vapor form, along with the uncondensable gases through a vapor line I2. The gasoline constituents are condensed in a condenser mounted in the line I2, and the resulting Products are conducted into a gas separator I4, from which the fixed or uncondensable gases are discharged through a suitable pressure valve controlled line, While the gasoline or pressure distillate is discharged through a iioat Valve controlled line, as shown.

By the time the charging stock has passed through the coil 6, it is heated to a temperature of from about 625 to 660 F., at which temperature it is conducted through lines I6 and I8, into the mid-portion of an enlarged pressure cracking and polymerizing chamber 20, in which the charging stock passes downwardly over a series of bailie plates in contact with high temperature vapors'` produced in another part* of the conversion operation.A In the normalA functioning of the apparatus, theoil stock required forthe coil 6 for cooling purposes, is considerably greater than the requirements for the chamber 20, andthe process in general, so that a portion of the preheated stock in the line I6 a valved line 22 and a cooler mounted therein, back to the charging line 4.V Instead of cycling oil through the line 22, the additional cooling in the tower 8 may be effected by other means.

The reflux distillate produced in thetower 8,

and which has roughly the boiling range of gas oil, is discharged througha line 24 and-forced into other parts of the apparatus by meansl of a is conducted through pump mounted therein. A portion of this refluxV A stock is preferably conducted through a valved 'line 26 and a cooler mounted therein and passed into the upper portion of the enlarged pressure chamber 20, where it passes in intimate contact with vapors as it flows downwardly over a. series of baflie plates in the upper part of chamber 20.

The remainder of the reflux distillate from the tower 8 is conducted on Jthrough the line 24 to a pipe still heater-28, where the distillate is conducted at a pressure of approximately 500 lbs. per square inch, rst through a convection tube bank 30, and then through a radiant tube bank 32. In passing through these tube banks,

the reflux or stock is heated from an inlet tem- Y perature of about '750 F. to a discharge temperature of from about 970 to 10l0 F., at which temperature it is conducted through a discharge line 34 into a three-way valve 36, and then through a valved transfer line 38 into the upperportion of an enlarged coking chamber 4t, which is one of a plurality of similar chambers used alternately v to collect liquid residuum, in accordance with the `process of the present invention.

The charging stock introduced. into the chamber 20 through line I8 is subjected to relatively -high cracking and polymerizing temperatures for va sufficient time to produce a heavy liquid polymer. The resulting mixture of heavy residual stock and lime suspended therein is conducted from the bottom of the chamber 20 through a line 42 and forced by means of a pump mounted therein through a three-way valve 44, and then throughy a valved line 46, directly into the trans fer line 38 beyond the valve therein. 'Ille heavy polymerized stock from the bottom of the chamber 20 has a temperature of from 800 to 865 F. and isyusually equal to from one-fourth to onethird by volume of the stock passing through the line 34, so that the temperature of the mixture in line 38 will be from about 91T-945 F.

The high temperature products conducted from the line 38 into the top of the coking chamber 40, 'comprise both liquidand vapor constituents which are separated in the chamber 40, the liquid constituents and lime being retained in the chamber to be later converted into coke, While the separated vapors are conducted through a valved vapor line 48 into a three-way valve 50,fand` then through aconnecting line 52 into the lowerportionv of the pressure cracking and polymeri'zing chamber 20. These vapors will have a temperature of from 885 to 900 F., so that they are particularly adapted for use in cracking, polymerizing, and otherwise conditioning the heavy charging stock passed into the chamber 20 through the line I8. After the high temperature vapors contact the charging stock in the lower portion of the chamber 20, and their temperature has been substantially reduced, they are brought in contact with reflux distillate introduced through the line 26. This ydistillate washes the vapors and holds back occluded heavy hydrocarbons for further reaction, and is in turn largely revaporized because of the high temperature maintained in the chamber 20. Y The resulting vapor mixture in the top of the chamber 20 is conducted therefrom at a temperature` of from 800 to 830 F. through a vapor line 54 and introduced into the lower part of the fractionating tower 8.

Theroperations carried out in the chamber 20 may be varied in certain details in order to produce a conditioned liquid Vof high specific gravity at the bottom of the' chamber.V For example, Vthe control of the reactions in the chamber. 20 is more readily eiected by passing a portion of lthe heavy charging stock and lime from the line I6 through a connecting valved line 56 and introducing it directly into the high temperature vapors in the line 52. This has the effect of cooling the vapors in the line 52, contacting them with lime and of lowering the contact temperature in the chamber 20. Furthermore, they quality of the body of high gravity polymerized ma- -terial collected in the bottom 'oft the VVchamber -2is'affected' by varying the'p'roportions of 'stock conducted respectively through thev lines: I8 andiSG.

The cracking and:.polymerization: offthe charglng stock4 carriedout. in the chamber 2'0. is ef'- fect'ed at a pressure of approximatelyA 225 lbs. per square-inch, and' at a temperature ofV from 820' to 850 F., so-that substantialA vaporization isprevented and there is no net loss by vaporization. In atypical operation, topped crudeoil charging stock of about 24 A. P. I. gravity was supplied to-the chamber 2l) inthe proportion of about 23 parts through the lineV 56 to about' 57 partsthrough the liner I8. While that' portion introducedY into the vaporl line 52 was cracked andpolymerized ataslightly higher temperature from that introduced-into the-chambr 20 through the-line I8, the combined operations produced a product of optimum quality for conversion into amarketable coke. In ord-inarypractice, a considerable body of material is maintained in the lower portion of the chamber4 20' to provide a.

suitable-soaking timelunder pressure to givea product of from 8 to 11l A; P. I. gravity. This polymerized productl contains no coke and very little-free carbon, since the cracking and polymerizing operation carried out in the chamber 20 iscontrolled to avoid coke-formation. In conditioning the polymerized material inthe chamber 20, it has been foundnecessary to supply a ratherA denite proportion of the preheated cha-rging stockto thevapor line 52. Attempts to introduce all of the-stock'through the line I8 haveresulted inthe production-of a much poorer quality of coke from the-polymerized stock.

The transfer line products from' the line 38 are continuously introduced into the ook-ing chamber 40 until the .chamber has been filled or substantially lled with the conditioned polymerized liquid oilv constituents. Thereafter, the transfer line products are directed by the threeway valve 36 through an alternate valved transfer line 58 into the-upper portion of a second coklng chamber 6D which is'of the same-structure-as the-chamber 48, the'chamb'er 60, ofcourse having been freed of coke from' any previous'use in the system. Whenl the-transfer line products are directed through the line -58-byjthe valve 38, the valve-44 will also` be -operatedto conduct the hot heavy polymersv from the-line 42 through a connecting line 82 into the line 58, and the threeway valve 50'will be turned to take' the vaporsfrom the coking chamber 60 through-a valvedV vaporline 84.

The-accumulation of-lquid in the chambers 4U and Ellis followed by means of thermocouples- (not shown) installed'in the chambers at various levels'tov serve as an indication of the approximate oil' level. 'IhermocouplesV locatedv in the vapor space will normally read'veryA close to the temperature at the upper part of thechamber,

for-example, these couples-may read'from 885 to 895 F. As soon as the liquid level covers one ofthe thermocouples-there-isfa marked drop in temperature from, say, 885 down to-8l0cl F., so that an operator will know the approximate'oil level and how fast the chamber is lling with the conditioned oil.

The three- way valves 36, 44 and 50 are-of a Well-known type, each of which may, if desired,

be--setto simultaneously connect into-allthree` oftheir connecting lines at the same time: This may be desirable, asfor example, whenchamber Mlis completely cut oi from the line 38, thevalve 50 may 'be-used; to receivevaporsfromf bothchambers 40- and Ill` and-irra-V heating' up period: z supply vapors from one;y chamber: totheother..

It will be notedlthat each ofifthe'zlinesag' 58,48; 62, 48 and 845, islprovided'r: with; independentcutoff valves.

berwhich is-cut out' of the systemfor'cleaning..

Thecollecting` chambers'V aref operated under' a. superatmospheric pressurev o'f fromr about, 200'1 tol 275 lbs. per vsquare inch, so `that-immecliatisely after' the chamber 401is'cut out'ot' the--systemandf-the Valves in lines-38, 46.*and248 are-closed,- thepressure on the chamber"is-.reducedaasthe-rstlstep in electingthe' coking-4 of the' hottar'collected in the chamber. by. opening a valve-inl a' run-downlline-Giwhich leadsto a= cooler and sump,I not: sh'oWn'i in thel drawing (the chamber 60v isalsowprovided with a., Since the largebody. of liquidi tar in the chamber 40 is at a-.hightem-perature; a.- comprising the*- similar line 66) considerable portion. thereof, lighter constituents, isl vaporized upon. the reduction in pressure, and' such constituents:` are discharged through-the line Il.y The pressure inv chamber 40' is reduced" to substantially Vatmospheric, and the-cokng-` of the-body of oilinthe chamber is. partially effected, but is completed'- bythe introduction ofI steam into the-loWer,por'- tion ofthe chamber, followed-by the introductionof Water.

When either 'of the chambers-40 or SIl'isgcut-'out of the system for coking,` and pressure reduced thereon, as foriexample the chamber 40,; steam- (notsuperlfieated)l is' suppliedV from a valved line- 68 and conducted' through one of the lines 10 Which connects-into ashort line -l2on the bottom f water is' admitted from a-valved-supplyfline 14 tov complete the-coking operation,` the waterl being admittedlfrom thefline Nfthroughlines T0 vand 12, into thelower part-fofthechamberd. The rate of Water supply to-thechamber' is usually controlled by Watching the pressure'developed in the chamber and-preventing the occurrence of a pressure-which will in any Way approach that von thewater'line. In the laterstages of the-coke-production Water is introduced intol the chamber to electits coolingdown-toV a-.point sufficiently. low that it may-be opened'forcoke removal.

Cokeremoval from the chamber 40, and of course, from t'hev chamber lwhen it was cut out of the system, is accomplished'by-any ofthe Well-known methodsor means.

After the-chamber'lID-'hasbeen cleaned of coke,-

the manf-heads are replaced, and the chamberis.A

filled with oil from a supply line I64 which fis-con nected into theA lines 10. Thisoil'istheusual charging stock or other oil taken from any source` and 'supplied-rapidly--to the chamber so-asto ll it quickly, after whichA the chamber is -cold'tested ata highV pressure, f in -orde-r--to insure' safe -operation, when itis subsequently cut back into theA systemplace of. chamber. 605 After-z the-cham'- ber=6'0`-:has been'llfedewitvh. thef-unvapori?.eei-tarry1 'Ihese valves. v are installed?asia'v safety:` feature'to absolutely preventrthe entrance'v of. any' high-temperature-productsA into '.thec'oking cha-m- The pressure reductionris .effected residue conditioned for ccking, the chamberM) is cut back into the system, While it is still iilled with the oil-introduced from the line 16.

In order to avoid confusion in the supply of steam or waterv and oil tothe-lower portions of the chambers 40 and..6,f.a detachable L-connection v8l) isprovided foreach of, the lines 10. This L-connection 80....must. be completely detached from the water line Mor-the steam supply 68 before oil can be supplied from :the line 15. changing the L-connection 80 in the manner indicated, itv is impossible to supply both oil and water or steam at the same time., There is therefore no possibility ofintroducing water or steam into a chamber after it has been connected into the cracking system.

A few hours before chamber 50 has become lilled with the conditioned tarry residue, and after chamber 40 vhas been cold tested, the switch valve Ell-is partially turned so that the opening in the 4plug communicates with both chambers Hand 60. This places full unit pressure on chamber 40.', which has been'previously filled with cold oil. Oil isthen drawn from chamber d through lines 12, 11a valved line 18 and a relief cooler (not shown) in order to slowly lower the level in the chamber. Hot vapors from. chamber 60 pass through line 64, switchwalve 55 and line 43, into the .upper part of the chamber 4D, and serve to force the oil out of this chamber and also to preheat the chamber. The rate at which oilis withdrawn from the chamber is controlled, so that the chamber will be almost empty by the time chamb er `lill has laccumulated its charge ofhot tarry residue. At thistime the threeswitchvalves 35, 44 and 50 are turnedv simultaneously to place chamber 40 in the system and cut outchamber 60. The residue in chamber 60 is then converted to coke in the manner described above.

When chamber 40 is first cut into the system, it ,will not have had a chance to become heated to full operating temperature and consequently some of .the vapors from 1ine738 will condense.V The condensate collected zin chamber 40 is withdrawn when, say V feet ofoilhasaccumulated therein.

The chamber may-not beheated sufficiently when thisf vamount of vcondensate has been formed, so .that a secondbatch of condensate may be allowed to vcollect in the chamber. vWhen the vapor terri--4 perature at the upper part of the chamber has reached about 890 F., any liquid in the chamber is quickly withdrawn throughv line 12, and the chamber is finally shut in by closing the valve in line 12. After nally preparing a chamber vin thisv manner, the temperature-of Vthe mixed feed entering the chamber is raised about 5 in order to dry out the lower portion of the chamber. This latter operation reduces the tarry residue -to the proper consistency so that in the subsequent` coking operationthe bottom of the chamber will contain coke .which can be easily broken, instead of a `tarry pitch. Although this method for switching chambers has` been found very satisfactory and is preferred, other methods may be used. The empty chamber may be heated with superheated steam or other hot fluid prior to switching it into the system. j

Repeated investigations have shown that the material collected in the coking chambers from the lines 38 and 53 is iiuid, even 4at the bottom of the chamber. The conditioned and polymerized tarry material introduced into the transfer lines frointhe chamber 20 is quickly heated in the transfer line to a temperature of about l935` F., so that some further .polymerization or `condi- ByA SIX

is fluid. Furthermore, an analysis showed that it contained `only about 12% of free carbonat the end of the filling. period. The free carbon y.

may run from 9% to about 24%. Y

As an example of a typical operation of the process, a topped crude oil, having a 24 A. P. I. gravity, was introduced through the line` 4, containing ().75 pound of hydrated lime per barrel of oil. This stock was'introduced at the rate of.

about 160 barrels per hour, heated to a temperature of about 640 F. in the coil 6, and 80 barrels per hour recycled through the line 22. The re-l maining 80..barre1s per hour were conducted through the line, I6, of which about l23 barrels per hour was conducted through the line 56, and

the remainder through ythe `line I8. fr The reflux condensate produced in the tower 8 had an A. P,.I.

gravity of i9 to 21, and approximately 285 barrels ,v hour of this stock at a temperatureof '755 F.;

was conducted to the pipe stillfurnace 28at `a pressure of 490 lbs. per square inch., VFrom to 2.0 barrels per hour of recycle 'stock was.A conducted through the'line 26. The hot-tar withdrawn from the chamber was conducted at a temperature of about 815 F. through the line 42 and supplied at the rate of about 85 Ybarrels per hour to the transfer line. Al period in excess of 10 hours is required to collect the body of tar in one of the chambers 40.01' 60. l v ,Y

In this instance, the pressure maintained in the Vchambers 40 and. 60 was 265vv lbs. per squarev inch, with a pressure of 235 lbs. per squareinch in the pressurercracking chamber 20.Y Gradually lower pressuresof 225 and 215 lbs. per squareinch were maintained in the tower 8 and receiver M,

respectively. The transferV line temperature at the point of discharge Vfrom the pipe still furnace was 985519., and that at the entrance to the colf:-L

ing chamber 935 F. while the temperature in the upper part of the coking chamber was 890 l.`

The `vapors conducted from the charnberfzl)` throughthe line 54- rwere atga temperature of 825 F., while those conducted through line `)I2 were 420 F. This operation was lcarried outy entirely by the use of the heavy topped crude stock introduced through the line `4, so that theA recycle stock produced in the tower 8 was-obtained fromy theheavier materialY by cracking, did not accumulate in the cracking operation, but was completely converted to other products.-

, The pressure distillate recovered amountedto '15% of the topped crude charge andhad an end;

point ot approximately 7120"V F. The amount of coke produced was equivalent to ,55- lbs. per bbl. of topped crude `chargedto the unit. This coke was fairly hard, making it. possible `to re.;

cover approximately in the form oflump. The coke vcontained 2-3% ksoluble matter and 8-10% volatile matter. Y y..

Having thus described the invention inY its pretact with petroleum oil vapors having a Sllfcent temperature to crack and polymerize the heavy stock, maintaining a pressure of at least about 200 lbs. per square inch in said chamber and preventing substantial vaporization, accumulating a substantial body of the polymerized stock in the lower portion of the chamber at a temperature in excess of 800 F. to provide a time reaction, continuously withdrawing polymerized stock from said body and quickly heating it to a temperature of about 935 F., conducting the resulting heated polymerized stock directly into the upper portion of an enlarged collecting chamber, gradually collecting an enlarged body of liquid polymerized stock in said chamber for a substantial period of time while retaining said collected liquid body at an average temperature in excess of 800 F., maintaining a pressure of at least about 200 lbs. per square inch in said collecting chamber while said polymerized stock is collected in said body, and thereafter coking the liquid body of polymerized stock collected in said collecting chamber by the successive steps of gradually reducing the pressure thereon over a period of time, passing steam through the collecting chamber from the bottom for a substantial period of time and thereafter introducing water into the bottom of the chamber for a substantial period of time.

2. The method of converting petroleum oils, which comprises passing 2 petroleum distillate stock in a confined stream of restricted cross section through a pipe still furnace and subjecting it to cracking conditions of temperature and pressure, discharging the resulting highly heated products from said pipe still furnace at a temperature of approximately 1000 F. and mixing therewith a minor proportion of a very heavy polymerized cil stock having a temperature of at least 800 F., an A. P. I. gravity of from about 8 to 12 and resulting from a cracking operation in which it has been conditioned under pressure for coking, conducting the resulting mixture into the upper portion of an enlarged chamber in which the vapors and unvaporized liquid oil constituents are separated at a pressure of at least 200 lbs. per square inch, accumulating the unvaporized liquid oil constituents in said chamber under conditions adapted to prevent substantial agitation until the chamber is substantially filled with liquid, discharging the separated vapors from the upper part of said chamber and subjecting them to a fractionation operation to separate out the desired gasoline from higher boiling constituents and uncondensable gas, isolating the filled chamber from the operation cycle and immediately coking the liquid contents of the chamber by the successive steps of gradually reducing the pressure thereon over a period of time, passing steam through the chamber from the bottom for a substantial period of time and thereafter introducing Water into the bottom of the chamber for a substantial period of time.

3. The method of converting petroleum oils which comprises passing petroleum distillate stock in a confined stream of restricted cross section through a pipe still heater and therein subjecting the stock to cracking conditions of temperature and superatmospheric pressure, discharging the resulting highly heated products of said distillate stock from said pipe still heater through a transfer line and mixing therewith in said transfer line a substantial but minor proportion of a very heavy polymerized oil stock which has been conditioned for. conversion to coke, conducting the resulting mixture through said transfer line at a temperature of about 950 F. into the upper portion of one of a plurality of enlarged chambers in which a pressure of at least 200 lbs. per square inch is maintained and wherein the vapors of the mixture are separated from unvaporized tarry oil constituents, continuously supplying said distillate stock to said pipe still heater and retaining said polymerized tarry oil constituents in said chamber under quiescent conditions until the chamber becomes substantially filled therewith, thereupon directing the stream of products in said transfer line into another of said enlarged chambers and isolating the filled chamber, continuing the alternate use of said plurality of chambers as collection chambers to thereby provide a continuous process, immediately upon isolating a chamber filled with liquid residue from the process cycle, effecting the coking of its tarry contents by the successive steps of gradually reducing the pressure thereon over a substantial period of time, then introducing steam into the bottom of the chamber for a substantial period, and thereafter introducing water into the chamber for a substantial period.

4. In a continuous process for converting petroleum oil, in which a reflux distillate produced in the conversion operation is passed in a confined stream of restrictedcross section through a pipe still furnace and subjected to a cracking temperature of from 960 to 1010 F. at a substantial superatmospheric pressure, and in which a topped crude cil stock is subjected to a pclymerizing operation in an enlarged contact chamber by heating it With high temperature gases and vapors produced in the conversion operation, the improvement which comprises subjecting said topped crude oil stock to a polymerizing operation at a temperataure above 800 F. to produce a heavy polymerized tarry residuum While preventing substantial vaporization, mingling said heavy tarry residuum while at a temperature of at least 800 F. with the high temperature products resulting from the heating of said reflux distillate and thereby raising the temperature of said `residuum, passing the resulting mixture into the upper portion of an enlarged collecting chamber in which vapors are separated from unvaporized liquid oil constituents under conditions adapted to prevent substantial agitation of the separated liquid oil, gradually accumulating said separated liquid oil constituents in said collecting chamber under high pressure until the chamber is substantially filled with the same, thereupon isolating the said collecting chamber from the conversion cycle by conducting the stream of mixed products into an alternate collecting chamber, coking the unvaporized liquid o il constituents in the isolated chamber by gradually reducing the pressure thereon to approximately atmospheric pressure, thereafter passing steam into the lower portion of the isolated chamber for a substantial period of time, and finally introducing Water into the lower portion of the chamber until the contents of the chamber have been coked and the chamber cooled to a point sufficiently low to permit opening of the same and removal of the resulting coke therefrom.

5. A continuous process for conditioning heavy petroleum oils to be coked, which comprises introducing fresh topped crude oil into an enlarged pressure cracking and polymerzing chamber and therein intimately contacting the topped crude oil with high temperature oil vapors Vand effecting the polymerization of said topped crude oil at a temperature between 800 and 900 F., continuously introducingthe topped crude oil into said chamber and maintaining it therein under a pressure of approximately 200 lbs. per square inch for a suiiicient period of time to polymerize the topped crude oil to a heavy tarry liquid product having an A. P. I. gravity of from 8 to approximately 11 and having a relatively low free carbon content, conducting hot tarry polymerized stock from said chamber and heating it quickly to a temperature of from Vabout 915 to 945 F., under a pressure in excess of 200 lbs. per'square inch then collecting said polymerized stock in a quiescent liquid body of the stock over a substantial period of time of at least ten hours, maintaining the collected liquid body of stock at an average temperature in excess of 800 F. and at a pressure in excess of 200 lbs. per square inch, and after a sufiicient body of said polymerized stock has been collected and converted into a` product not containing in excess of from about 9% to 24% of free carbon, subjecting the liquid body to coking conditions to convert the stock into marketable petroleum coke.

6. A continuous process'ior converting corrosive petroleum oils by the Vuse of lime wherein the direct heating of the lime with the oil by firing is avoided, which comprises Vpassing a mixture of high temperature vapors having a temperature in excess of 800 and produced in the conversion operation into an enlarged unheated contact chamber in intimate contact with a mixture of a heavy oil and lime to purify said vapors, maintaining a superatmospheric pressure of at least 200 lbs. per square inch in said contact chamber to prevent substantial vaporiz'ation of said heavy oil, passing the vaporsV from said contact chamber into a fractionating tower and thereinproducing a reflux condensate free of lime, passing said reflux condensate in a confined stream of restricted cross-section through a pipe still furnace and subjecting it to a cracking the resulting highly heated products from substantial superatmospheric pressure, conducting the resulting highly heated products from said pipe still furnace into a transfer line and introducing thereinto and mingling with said products a stream of the highly heated heavy oil and lime produced in said;contactY chamber, passing the resulting mixture of products and lime in said transfer lineinto an unheated separating chamber in which liquid oil constituents and lime are separated from vapors, and conducting vapors from said separating chamber to supply the high temperature vapors introduced into said unheated contact chamber.

'7. In a continuous process for converting petroleum oil, in which a reflux distillate produced in the conversion operation is passed in a confined stream of restricted cross section through a pipe stillfurnace and subjected to a cracking' temperature in the neighborhood of 1000 F. at a substantial superatmospheric pressure, and in which a topped crude oil stock is subjected to a polymerizing operation in an enlarged chamber by heating it with high temeprature gases and vapors produced in the conversion operation, the improvement whichV comprises subjecting` said topped crude oil stock to a-polymerizing operation at a temperature above 800 F.' to produce a heavy polymerized tarry residuum while pre venting substantial vaporization, mingling said heavy tarry residuum While at a temperature of at least 800 F. with the high temperature products resulting from Vthe heating of said reflux distillate and thereby raising the temperature of said residuum, passing the resulting mixture into the upper portion of an enlarged chamber in which vapors are separated from unvaporized liquid oil .constituents underV conditions adapted to prevent substantial agitation of the separated liquid oil in said chamber, gradually accumulating said separated liquid oil constituents in said chamber'under high pressure until the chamber is substantially filled with the same, thereupon isolating the chamber from the conversion' cycle by conducting the stream of mixed products into an alternate chamber, and coking the ur'ivapo'r` ized liquid oil constituents in the isolated chamber by the successiveV steps of gradually reducing the pressure thereon over a period of time, passing steam through the isolated chamber fromV the bottom over a substantial period of` time, and thereafter introducing vvater into the bottom of the isolated chamberfor Va substantial period of time. Y s s Y 8. A continuous process as deiinedby claim 'I in which the topped crude oil stock subjected to the polymerizing and coking operations includes Y a minor proportion of lime intimately mingled therein. Y y

` 9. The method of converting petroleum oils as defined by claim 2 in which a smallproportion of lime is included in the heavy polymerized oil stock mixed with the highly heated products from the pipe stillY furnace. V10. The method of converting -petroleum oils as defined by claim 3 in which a small proportion of' lime is included with'the heavy poly- Y said enlarged chamber and brought in contact 1 with high temperature oil vapors therein.

DAVID G. BRANDT.

with highY CERTIFICATE CF CORRECTION. Patent No. 2,516,951. v April zo, 19M.

DAVID C. BRANDT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correcti on as follows: Page LA, first column, line 25, for "72, "(7" read 72, 'YO-4; page 6, first column, line h6,

strike out "ing the resulting highly heated products from" and insert instead --ng temperature of from 9600 to .LOlOO F. at a; vand that the said Letters Patent should be read with this correction therein that the same may Conform to the record of the case in the Patent Office. I

Signed and sealed this 25th day of May, A. D. 1914.5.

. Henry Van Arsdale v (Seal) Acting,- Commisioner of patents.

Images