US2210265A - Conversion of hydrocarbon oils - Google Patents

Description

Aug. 6,1940. SEGUY 2,210,265 I I CONVERSION OF HYDROCARBON OILS Filed Aug; 31, 1939 SEPARATING 8. FRMTIONA FRACTIONATOR COLUMN FURNACE 2 FURNACE 68 SEPARATING CHAMBER ji DISTILLING FURNACE RECEIVER 3(5) 'IJ 79 INVENTOR JEAN DELATTRE SEGUY' ATTORNEY Patented Aug. 6, 1 940 UNITED STATES PATENT OFFICE 2,210,265 v f v CONVERSION OF HYDROCARBON OILS Jean Delattre Seguy, Chicago, Ill., assignor to- Universal Oil Products Company, Chicago, IlL, acorporation of Delaware a r Application August 31', 1939, Serial No. 292,881

4 Claims. (01.196 49) This invention relates specifically to an improved cracking system involving a combination of interdependent steps comprising vapor-phase cracking, reforming and flash distillation which cooperate to produce, from the charging oil and intermediate products of the process, high yields of good antiknock gasoline and minor yields of good quality liquid residue and gases.

various steps of the process are combined in an One specific embodiment of the invention comprises cracking, in essentially vaporous state, a condensate resulting, as hereinafter described, from fractionation of relatively clean vaporous products of the process, commingling the'resulting products with hydrocarbon oil charging stock and with other conversion products of the process, derived as hereinafter described, and, separat ingthe mixture into saidrelatively clean vapors and heavier liquid fractions, fractionating said relatively clean vapors to condense therefrom,

as said condensate supplied to the vapor-phase cracking operation, components which contain no substantial quantity of gasoline fractions and lated to produce therefrom high yields of full boiling range gasoline of improved antiknock value, separating the products of thevreforming I v p H a version products aredirected from coil [through operation into liquid and vaporous fractions, separately fractionating the latter to condense therefrom as reflux condensate components boiling above the range of said gasoline of improved antiknock value, supplying said reflux condensate to the same separating zone to which said charging stock and con-version products of the vaporphase cracking operation are supplied, subjecting fractionated vapors resulting from the last described fractionating step to condensation to form gasoline which is recovered and; separated from the uncondensed gases, supplying said liquid fractions derived from the first mentioned separating zone and from the separating zone to which said reformed products are suppliedto a reduced pressure distilling zone and therein effecting their appreciable further vaporization,

supplying a portion of said uncondensed gases to said distilling zone to assist said distillation, recovering the resulting unvaporized residual liquid, separately cracking the vapors evolved'in said distilling zone in the'presence of said uncondensed gasessupplied thereto and supplying the resulting conversionproducts to the same separating zone to 'whichsaid charging stock, said conversionproducts of the vapor-phase cracking step andv said reflux condensate are supplied.

It will be apparent from the above that the contemplates a process involving less than the entire combination of steps above recited, as there are several suchlesser combinations which involve novel and advantageous departures from the prior artand are, therefore, within the scope of the broader aspectsof the invention.

Theaccompanying drawing is essentially a flow diagram of ,a system incorporating the combinae tion of cooperative stepsprovided by theinventionand in which the above outlined process, as well asv various modifications thereof involving less than the entire combination, may be conducted.

Referring to the drawing, the vapor-phase cracking coil l, to which is supplied a clean condensatej of relatively low end-boiling point (say 600 to 650 F.) is disposed in furnace 2 and the oil supplied, as will'be later described, to this coil is substantially completelyvaporized therein andheated'during its passage. therethro-ugh to the desired cracking temperature. a The resulting conline 3 and valved into' separating and fractionating column 5 andipreferably are cooled prior to their introduction into the latter zone sufficiently'to prevent substantial further cracking thereof. ,In the casehere illustrated, this cooling is accomplished by directly commingling suitable cooling fluid with the conversion products passing throughline 3 and may be assisted, when desired, by pressure reduction as the-products pass throughvalve'4 in' this line.

I may'e'mploy a portion or all of the hydrocarbon oil charging stock-for the process ascooling material in, line 3 by directing the same from pump 8, to whichthe charging stock is'supplied through line 6 and valve], through line9, line l0 andvalve ll into line 3 and, when desired, reflux condensate recovered from the vaporous products of-..the reforming operation hereinafter described may be commingled, all or. in part, with or without prior cooling, with the vapor-phase conversion products being supplied to the column 5 to serve as cooling material for the latter. The provisions for accomplishing cooling by the latter method will be later described.

The charging stock for the process may be any desired type of hydrocarbon oil ranging from light distillate to crude petroleum, reduced crude or the like and any portion of the charging'stock not commingled with the conversion products prior to their introduction into column 5 may be supplied directly to the latter zone at any desired point therein, whereby it is also commingled with the conversion products and assists cooling and fractionation of the latter. Line I2, controlled by valve 13 and communicating with line 9 and column 5, is provided in the case here illustrated for introducing all or anydesired portion of the charging oil into the latter zone.

Conversion products of a third cracking step are also supplied to column .5, as will be later described, and the commingled materials supplied to this zone are separated therein into a relatively clean vaporous stream, having an endboiling point of the order of 600 to 650 F, for example, and heavier liquid fractions. The latter are directed from this zone through line I4 and valve [5 to distilling chamber I6 and the relatively clean vapors are directed from column 5 through line H and valve I 8 to fractionation in fractionator l9.

The vapor supplied to fractionator l9 are partially condensed therein to form the clean condensate supplied as cracking stock to coil l and the remaining lighter vapors are further fractionated in this zone toform a lighter condensate consisting essentially of heavy gasoline fractions, leaving a fractionated vaporous product which consists essentially oflight gasoline fractions of good antiknock value andgases.

The vapor-phase cracking stock is directed from fractionator l9 through line 20 and valve 2| to pump 22 by means of which it is supplied through line 23 and valve 24 to vapor-phase cracking treatment, in the manner above described, in'coil I. y

The lighter condensate formed in fractionator I9 is directed therefrom through line 25 and valve 25 to pump 21 by means of which it is supplied through line 28 and valve 29 to reforming treatmentin heating coil 30, wherein it is heated to a high cracking temperature at substantial superatmospheric pressure by means of heat supplied from furnace 3!, wherein coil 30 is disposed, The cracking conditions employed in coil 30 are regulated to effect reforming of the heavy gasoline fractions supplied thereto (i. e., their conversion into'high yields of gasoline of lower initial boiling point and improved antiknock value) The reformed products are directed from coil 30 through line 32 and valve 33 into separating chamber 34 and preferably are cooled prior to their introduction into the latter zone sufficiently to prevent their appreciable further cracking and deleterious secondary reactions. This cooling may be accomplished inany well known manner and, in the case here illustrated, provision is made for introducing suitable cooling oil into line 32ythrough line 35 and valve 35'. Regulated quantities of the. vapor-phase cracking stock from fractionator l9 may, when desired,'be employed as cooling oil in line 32, this material preferably being removed. fromline 23 and cooled to the desired temperature in any well known manner, not illustrated, prior to its introduction into line 32. Provision is also made for utilizing a regulated portion or all of the charging oil to cool the reformed products from coil 30. This is accomplished in the case here illustrated by directing charging oil from line 9 through line 86 and valve 81 into line 32.

Chamber 34 is preferably operated at a substantially reduced pressure relative to that employed at the outlet of coil 30. This reduction in pressure assists cooling of the reformed products and is accomplished as the latter pass through valve 33 in line 32.

In chamber 34 separation is effected between vaporous and heavy liquid components of the commingled reformed products and cooling oil, the liquid components being supplied from this zone through line 36 and valve 31 to distilling chamber [6, while the vapors are directed from chamber 34 through line 38 and valve 39 to fractionation in fractionator 40 wherein their components boiling above the range of the desired gasoline product of the process are condensed as reflux condensate.

The reflux condensate formed in fractionator '40 is directed therefrom through line 4| and valve 42 to pump 43 by means of which it is fed through line 44 and maybe supplied therefrom, all or in part, through line 45 and valve 46 into line 3 and thence to column 5 or a regulated portion or all of this material may be directed from line 44 through line 41, valve 48 and line 43 into column 5, after commingling in line 49 with relatively hot conversion products of the third cracking step of the system, which will be later described. It is also within the scope of the. invention to supply all or any desired portion of the reflux condensate formed in fractionator 40 from line 45 through line 50 and valve 5| directly to column 5 without first commingling the same with other conversion products. In order that the reflux condensate from fractionator 40 may function efficiently as a cooling medium in the zone or zones to which it is supplied, it may, when desired, first be passed through cooler 52 and therein cooled to the desired temperature, this being accomplished by closing valve 53 in line 44 and opening valves 55 and 51 in the respective lines 54 and 56 which connect cooler 52 with line 44.

When desired, instead of separating heavy liquid fractions from vapors in chamber 34 the total reformed products from coil 30 and the cooling oil commingled therewith may be supplied directly to fractionator 40, by well known means not illustrated, whereby all the components of these-materials boiling above the range of the desired gasoline are included in the reflux condensate formed infractionator 40, the heavy liquids being subsequently separated therefrom in chamber 5. a

The liquid conversion products supplied to chamber l6 from chamber 34 or chamber 5 or both, as the case may be, are appreciably further vaporized in this zone to form a heavier residual liquid product and evolve vaporous fractions suitable for further'cracking "treatment. Chamber l6 may be operated at asubstantially reduced pressure relative to that employed in chamber 5 and/or in chamber 33 to assist vaporization in this zone and, in the preferred embodiment'of the invention, vaporization in chamber I6 is also assisted by the introduction theretoof normally gaseous products of the process, as will-be later described. The residual liquidformed in'chamher It is directed therefrom through line 60 and valve GI to cooling and storage or elsewhere, as desired,'and the vapors evolved'in chamber I6, including any normally gaseous fractions supplied to this zone, are directed therefrom through line 62 and'valve 63 to pump or compressor 64 wherefrom they are supplied through line 65 and valve 66 to further cracking treatment in heating coil 61.

' Coil 61 is disposed in furnace 68, the vapors or mixture of vapors and gases passing therethrough being heated to the desired cracking temperature, preferably at a pressure at least as high as that employed in column 5. When substantial quantities of normally gaseous fractions are included in the materials supplied to coil 61, the conditions employed in the latter zone may be regulated to eifect conversion of the gases, as Well as the normally liquid fractions, into sub stantial additional yields of gasoline.

The products formed in coil 61 are directed therefrom through line 69, valve 10 and line 49 into column 5 to commingle therein and undergo separation and fractionation with the charging stock, conversion products from coil I and reflux condensate from fractionator 40;-

The fractionated vapors which, as aforementioned, consist essentially of low-boiling gasoline fractions and gases, are removed from the upper portion of fractionator I9 through line H and valve 12, while fractionated vapors from fractionator 40, which comprise good antiknock gasoline fractions of higher end-boiling point than those removed as vapors from fractionator I9 are removed from fractionator 40 through line l3 and valve 14 and, although these two different boiling range gasolines may, within the scope of the invention be separately condensed and recovered as separate products, they are, in the particular case here illustrated, commingled in line 15 and supplied therefrom to cooling and condensation in condenser I5. The resulting distillate and uncondensed normally gaseous products are directed from condenser '56 through line I1 and valve 18 to collection and separation in receiver 19. The distillate which collects in this zone comprises the final motor fuel product of the process and is directed from the receiver through line and valve 8| to storage or to any desired further treatment.

Gases collected in receiver 19 are discharged therefrom, at least in part, through line 82 and valve 83 to storage or elsewhere, as desired. Preferably, however, a regulated portion of these gases is utilized to assist vaporization in chamber I5 and to accomplish this, provision is made for supplying gases'from the receiver through line 84 and valve 85 into chamber I6 to directly commingle in this zone with the liquid products undergoing vaporization therein and assist their vaporization by the partial pressure effect exerted by the gases.

When additional heat is required to obtainthe desired vaporization in chamber I6, it may be supplied to this zone by heating the gases, in any well known manner not illustrated, prior to their introduction into chamber I6.

The operating conditions which may be employed to successfully conduct the process of the invention in a system of the character illustrated and above described depend upon the type of charging oil utilized and the market requirements With respect to the characteristics of the products. However, as an example of the-operating conditions which maybe employed inmost instances, a temperature of the order of 975 to 1200 F. may be employed at the outlet of vaporphase heating coil I, preferably with a superatmospheric pressure at this point in the system of the order of 100 pounds, or more, per square inch, the temperature and pressure being correlated to give substantially complete vaporization of the products leaving coil 1. Chamber 5 is preferably operated at substantially the same or somewhat lower pressure than that utilized at the outlet of coil I and this pressure may be substantially equalized or reduced in the succeeding fractionating, condensing and collecting equipment. Reforming coil 30 is preferably operated with an outlet temperature of from 925 to 1050" F., or thereabouts, with a superatmospheric pressure measured at the outlet of the coil of from 200 to 1000 pounds, or thereabouts, per square inch. The succeeding separating chamber 34 is preferably operated at a substantially reduced temperature and pressure, the latter ranging, for example, from 30 to 150 pounds, or thereabouts, per square inch and the reformed products preferably enter this zone at a temperature of the order of 750 to 875 F. The pressure employed in chamber 34 may be substantially equalized or reduced in the succeeding fractionating, condensing and collecting equipment. Distilling chamber I5 is preferably operated at a substantially reduced pressure relative to the pressure employed in column 5 and preferably also lower than the pressure employed in chamber 34, the pressure in chamber I6 ranging, for example, from 30 to 100 pounds, or thereabouts, per square inch. Relatively mild cracking conditions are preferably employed in coil 61, the temperature'at the outlet of this zone ranging, for example, from 800 to 900 F. when a superatmospheric pressure above 150 pounds or thereabouts, per square inch, is I utilized in this zone, while higher temperatures up to 1050 F., or thereabouts, may be utilized with lower pressures. Preferably, the pressure employed at the outlet of this zone is somewhat higher than that utilized in column 5 in order to permit introduction of the heated products from coil 61 to chamber 5 without pumping or compression thereof.

As an example of one specific operation of the process as conducted in a system such as illustrated and above described, the charging stock is a Texas topped crude of approximately 22 A. P. I. gravity which is supplied, in part, to transfer line 32 leading from reforming coil 30 to chamber 33 and, in part, to column 5. The temperature employed at the outlet'of coil I is approximately 1100 F. with a pressure at this point in the system of about '75 pounds per square inch. Substantially the same pressure is utilized in column 5 and the vaporous stream supplied from the latter zone to fractionator I9 has an end boiling point of about 650 F. The condensate supplied from fractionator I9 to coil I has the same end-boiling point and contains over of the fractions boiling between 400 and 600 F. The overhead vaporous stream removed'from fractionator I9 has an end-boiling point of approximately 275 F. and the condensate supplied from fractionator I9 to reforming coil 30 has an end-boiling point of approximately 450 F. and contains over of the fractions boiling above 250 F. The temperature employed at the outlet of reforming coil 30 is approximately 1000 F. with a superatmospheric pressure at this point in the system of about 300 pounds per square inch. J The pressure employed in chamber 34 is reduced to approximately 90 pounds per square inch and the temperature of the reformed products entering the latter zone is reduced to approximately 870 F. Fractionator is also operated at a superatmospheric pressure of approximately 90 pounds per square inch and the reflux condensate in this zone is cooled and commingled, in part, with the stream of heated products passing from coil I to column 5 and, in part, to the stream of heated products passing from coil 61 to column 5. The end-boiling point of the overhead vaporous stream removed from fractionator 40 is approximately 400 F. Chamber I6 is operated at a superatmospheric pressure of about 30 pounds per square inch and gases from receiver 19 are supplied to this zone to assist vaporization therein, the receiver being operated at a superatmospheric pressure of about pounds per square inch. The temperature employed at the outlet of coil 61 is approximately 975 F. with a superatmospheric pressure at this point in the system of about 100 pounds per square inch.

The above described operation will yield per barrel of charging stock approximately 51% of 400 F. end-point gasoline which is a blend of the gasolines recovered from the fractionated vaporous stream from fractionator l9 and the fractionated vaporous stream from fractionator 40. Approximately 22% based on the charging stock of liquid residue, having good fuel oil characteristics, is produced and the remainder of the charging stock is accountable for as uncondensed gases.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises reforming a light condensate, derived as hereinafter set forth and consisting essentially of heavy gasoline fractions, under thermal cracking conditions regulated to produce therefrom high yields of gasoline of lower initial boiling point and improved antiknock value, separating from the products of the reforming operation a fractionated vaporous stream consisting essentially of said improved antiknock gasoline and gas, condensing said gasoline and separating the same from the uncondensed gases, separating selected heavier liquid components from the reformed products and commingling the same with at least a portion of the hydrocarbon oil charging stock for the process and with other conversion products of the process derived as hereinafter set forth, separating the resulting mixture into. a relatively clean vaporous stream and a stream of heavier liquid fractions, substantially vaporizing the latter in a zone of reduced pressure relative to that at which the last mentioned separation is effected, whereby to form additional vapors and heavier, non-vaporous residue, separately cracking said additional vapors and commingling resulting conversion products, as aforesaid, with said selected heavier liquid components of the reformed products, fractionating said relatively clean vapors to form a clean condensate substantially devoid of gasoline, a lighter condensate consisting essentially of heavy gasoline fractions and comprising the oil subjected to said reforming, and a vaporous stream consisting essentially of gas and good antiknock, light gasoline fractions of lower end boiling point than said gasoline recovered from the reformed products, condensing said light gasoline and separating the same from the uncondensed gas, separately cracking said clean condensate in essentially vaporous state and commingling resulting products, as aforesaid, with said selected heavier liquid components of the reformed products.

2. The process defined in claim 1 wherein hydrocarbon oil charging stock for the process is commingled with the reformed products prior to the separation therefrom of said selected heavier liquid components, whereby to include at least a portion of said charging oil therein.

3. The process defined in claim 1 wherein hydrocarbon oil charging stock for the process is commingled with the reformed products prior to separation of their vaporous and liquid components, and wherein a liquid fraction, heavier than said selected liquid components of the reformed products and including heavy fractions of the charging stock, is separated from the mixture of charging oil and reformed products and supplied to said zone of reduced pressure vaporization.

4. The process defined in claim 1 wherein a portion of said uncondensed gases is introduced into said zone of reduced pressure vaporization to assist vaporization therein and commingled with said additional vapors supplied to the second mentioned cracking step.

JEAN DELA'I'TRE SEGUY.

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