US2112376A - Conversion of hydrocarbon oils - Google Patents

Description

March 29, 1938. J. c. MORRELL CONVERSION OF HYDROCARBON OILS Original Filed Oct. 8, 1954 FRACTIONATOR FURNACE l3 DISTILLING COLUMN\ INVENTOR HEAT EXCHANGER FURNACE 46 y TORN JACQUE Z;

Patented Mar. 29, 1938 UNITED STATES PATENT OFFICE CONVERSION OF HYDROGARBON OILS Jacque C. Morrell, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application October 8, 1934, Serial No. 747,268 Renewed February 4, 1936 6 Claims. (Cl. 196- 48) This invention particularly re e s o an As another feature of the invention all or a proved process for the fractional distillation of portion of the heat required for fractional distilhydrocarbon oils of relatively wide boiling range, lation of the charging stock may be supplied such as crude petroleum, for example, accomthereto by indirect heat exchange between the pendently controlled conditions, of selected relafrom the heating coil to which the low-boiling tively low-boiling and high-boiling fractions of fractions resulting from said fractionaldistilthe charging stock from the fractional distilling lation of the charging stock are supplied, and/or operation as well as further conversion Within the heating coil to which the low-boiling fracpanied by the pyrolytic conversion, under indecharging stock and the highly heated products 5,

10 the same system, of selected relatively low-boiltions of the intermediate conversion products are 10,

ing and high-boiling intermediate conversion supplied. Aside from furnishing heat for the products of the process. fractional distillation of the charging stock, this The present invention offers a simple and method of operation serves to cool the highly unified system for the fractional distillation of heated products from either or both of said heathydrocarbon oils of relatively wide boiling range ing coils sufiiciently to prevent'their excessive 15 accompanied by the selective conversion of rela further conversion. However, in any case, the tively low-boiling and relatively high-boiling highly heated products from both heating coils fractions of the charging stock as Well as, relaare cooled sufficiently to prevent their excessive tively low-boiling and high-boiling fractions of further conversion in the reaction chamber by the intermediate conversion products of the direct contact with the relatively high-boiling 20 process. Selected relatively low-boiling fractions fractions of the charging stock and of the interof the charging stock and selected relatively lowmediate conversion products and when desired, boiling fractions of the intermediate conversion particularly in case a portion or all of the excess products of the process are each subjected to inheat from both streams of highly heated proddependently controlled conversion conditions of ucts from the heating coils is required to effect elevated temperature and superatmospheric presthe desired degree of conversion of the higher sure in a separate heating coil succeeded by a boiling oils with which they are commingled in high-pressure reaction chamber, to which reacthe reaction chamber, all or a portion of the heat tio C b Se il ng fractions of required for fractional distillation of the chargthe charging stock and selected high-boiling ing stock may be derived from any other suitable 30 fractions of the intermediate conversion products source. are directly supplied, whereby said relatively high- In one specific embodiment the invention comboiling fractions are heated by commingling With prises subjecting hydrocarbon oil charging stock the highly heated relatively low-boiling fractions for the process, comprising an oil of relatively and subjected, in the reaction chamber, to less wide boiling range, to fractional distillation at 35 severe conversion conditions than those to which substantial superatmospheric pressure whereby the relatively low-boiling oils are subjected in to separate the same intorelatively low-boiling the heating coils. fractions, comprising the overhead vaporous As a special feature of the present invention, products, and relatively high-boiling fractions,

the overhead vaporous products resulting from comprising condensate or bottoms from the disthe fractional distillation of the charging stock tilling operation, subjecting said low-boiling vaare preferably pplied, While still in vaporous porous fractions to conversion conditions of elestate to the heating coil wherein they are subvated temperature and superatmospheric pres- .l' conversion e rming at relatively sure in a heating coil, introducing the stream of high temperature, without being first subjected highly heated products from said heating coil 45 to condensation, which would result in a coninto an enlarged reaction chamber, also mainsiderable loss of heat, and, in order to obviate tained at superatmospheric pressure, and the use of a vapor pump to pass the hot vaporous mingling therewith said high-boiling fractions of products from the topping operation through said the charging stock, withdrawing both vaporous 5O heating coil, the topping operation is preferably and liquid conversion products from the reaction conducted at a pressure sufficiently higher than chamber, subjecting the latter to further vaporthat employed in the heating coil to overcome ization at substantially reduced pressure, subthe drop in pressure, due to friction, through the jecting the vaporous conversion products, includheating coil and succeeding portions of the sysing those resulting from said further vaporizatem. tion, to fractionation in a separate fractionating 55 zone, whereby their insufiiciently converted components are condensed as reflux condensate and separated into selected relatively low-boiling and high-boiling fractions, subjecting fractionated vapors of the desired end-boiling point from said separate fractionating zone to condensation, collecting and separating the resulting distillate and gas, returning said relatively high-boiling fractions at the reflux condensate to the reaction chamber for further conversion, subjecting the relatively low-boiling fractions of the reflux condensate to independently controlled conversion conditions of elevated temperature and superatmospheric pressure in a separate heating coil and introducing heated products from said separate heating coil into the reaction chamber.

The accompanying diagrammatic drawing illustrates one specific form of apparatus in which the invention may be practiced. It should be noted that the optional methods of operation provided by the present invention are not equivalent but may be selected to suit requirements in order to give the process greater flexibility.

Referring to the drawing, hydrocarbon oil charging stock for the process, preferably comprising an oil of relatively wide boiling range containing an appreciable quantity of both relatively low-boiling and relatively high-boiling components, such as crude petroleum, for example, is supplied through line l and valve 2 to pump 3 wherefrom it is fed through line 4, valve 5, heat exchanger 6, line I and valve 8 into distilling column 9, wherein it is subjected to appreciable vaporization and fractional distillation. In the particular case here illustrated the heat required for fractional distillation of the charging stock may be supplied thereto in heat exchanger 6 by indirect contact and heat exchange between the charging stock and highly heated conversion products of the process, which are supplied to this zone, as well be later more fully described. It is however, also within the scope of the present invention to employ a heating coil of any conventional form for the charging stock or to impart thereto all or a portion of the heat required for its fractional distillation in any other well known manner, not illustrated.

Distilling column 9 is preferably operated at a substantially superatmospheric pressure in order to eliminate pumping of the overhead vaporous products from this zone which are supplied to cracking coil l2. In the case here illustrated, the charging stock is separated by fractional distillation in column 9 into a selected overhead vaporous product of the desired end-boiling point and bottoms, which latter comprise components of the charging stock remaining unvaporized in column 9 as well as the components which are condensed in this zone as reflux condensate. It is, of course, also within the scope of the invention, particularly in case the charging stock contains any desirable low-boiling, intermediate or high-boiling fractions which it is not desired to subject to conversion, to separate the charging stock into more than two selected fractions and to withdraw said desirable components such as, for example, straight-run gasoline of good antiknock value, lubricating oil, asphaltic material, etc., from the system by well known means, not illustrated in the drawing.

The selected low-boiling components of the charging stock remaining uncondensed in column 9 are withdrawn, in the case here illustrated, from the upper portion of this zone through line In to be supplied therefrom through valve II to conversion or reforming in heating coil l2.

When desired, a regulated portion of the overhead vaporous product from column 9 may be subjected to condensation, by well known means not illustrated, for the purpose of forming distillate which may be utilized as a refluxing medium in column 9 by recirculating said distillate to the upper portion of this zone, by well known means not illustrated. This is only one of the many well known satisfactory methods which may be employed for assisting fractionation in column 9 and maintaining the desired vapor outlet temperature from this zone so as to control the end-boiling point of the materials subjected to conversion in heating coil l2.

Heating coil I2 is located within a furnace l3 of any suitable form, by means of which the heat required for accomplishing the desired conversion of the low-boiling components of the charging stock is supplied thereto. Heating coil i2 is also preferably operated at a substantial superatmospheric pressure and the highly heated products are discharged from this zone through line 84 and may be directed, all or in part, through line l5, valve l6, heat exchanger 6, line I! and valve l8 into reaction chamber 29. The highly heated products from heating coil l2 passed, as illustrated, through heat exchanger 6, serve to supply to the charging stock all or a portion of the heat required for its fractional distillation. When desired, all or a regulated portion of the stream of hot vaporous products from heating coil l2 may by-pass heat exchanger 6 by diverting the same from line 15 through valve 19 in line 14 into line I! and thence to reaction chamber 20.

In case only a minor portion or none of the highly heated products from heating coil l2 are passed through heat exchanger 6 to be cooled by indirect contact with the charging stock the heat contained in these products may be utilized to assist conversion of the relatively high-boiling oils supplied to reaction chamber 29, as will be later more fully described, in which case said high-boiling oils serve to cool the highly heated products from heating coil l2 sufiiciently to prevent their excessive further conversion in reaction chamber 20.

In the case here illustrated, the high-boiling fractions of the charging stock withdrawn from the lower portion of column 9 through line 2| and valve 22 to pump 23 are fed therefrom through line 24, valve 25 and line 52 into reaction chamber 20.

Reaction chamber 20 is also preferably operated at a substantial superatmospheric pressure and, although not indicated in the drawing, is preferably insulated to prevent the excessive loss of heat therefrom by radiation so that conversion of the various oils. supplied to this zone, and particularly their vaporous components, may continue therein. The heat contained in the products from heating coil l2 and/ or heating coil 45, which latter are also supplied to the reaction chamber, as will be later more fully described, serving to heat the higher boiling oils supplied to this zone and effect their appreciable conversion therein at a temperature somewhat lower than the temperatures employed in the heating coils. In the particular case here illustrated both vaporous and liquid conversion products are withdrawn from the lower portion of chamber 20 through line 56 and valve 57 and are introduced into vaporizing chamber 26. It will be understood, however,

that, when desired, all or'a regulated portion of the vaporous products may be separately withdrawn from chamber 20 at any desired point in this zone, by well known means not illustrated, in which case the separately withdrawn vapors may be supplied, all or in part, direct to fractionator 29 or may be introduced, all or in part, into vaporizing chamber 26 at any desired point in this zone, by well known means not shown in the drawing.

Chamber 26 is preferably operated at a substantially reduced pressure relative to that employed in the reaction chamber, by means of which further vaporization of the liquid conversion products supplied to this zone from reaction chamber 20 is accomplished. Residual liquid remaining unvaporized in chamber 26 may be withdrawn from the lower portion of this zone through line 58 and valve 59 to cooling and storage or to any desired further treatment. The vaporous products evolved in chamber 26 as well as any supplied to this zone from the reaction chamber may be directed through line 2'! and valve 28 to fractionation in fractionator 29, together with any vaporous products which may be supplied, as previously mentioned, to fractionator 29 direct from reaction chamber 20.

The insuiiiciently converted components of the vaporous products supplied to fractionato-r 29, including their fractions boiling above the range of the desired final light distillate product of the process, as well as, when desired, regulated quantities of any selected high-boiling components of the desired light distillate product which are of inferior anti-knock value, are condensed in this zone as reflux condensate and, in accordance with the features of the present invention, are separated into selected relatively low-boiling and high-boiling fractions. The relatively low-boiling and high-boiling fractions of the reflux condensate are each subjected to further conversion within the system under different conversion conditions, as will be later more fully described.

Fractionated vapors of the desired end boiling point, preferably comp-rising materials within the boiling range of motor fuel of good anti-knock value, are withdrawn, together with uncondensable gas produced by the cracking operation, from the upper portion of fractionator 29through line 30 and valve 3! to be subjected to condensation and cooling in condenser 32. The resulting distillate and gas passes through line 33 and valve 34 tocollection and separation in receiver 35. Uncondensable gas may be released from the receiver through line 35 and valve 3'! to absorption, storage or elsewhere, as desired. The distillate collected in receiver 35 may be withdrawn there from through line 38 and valve 39 to storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 35 may be recirculated by well known means (not shown) to the upper portion of fractionator 29 to serve as. a refluxing and cooling medium in this zone to assist fractionation of the vapors and to maintain the desired vapor outlet temperature from the fractionator.

Selected low boiling fractions of the reflux condensate formed in fractionator 29 may be withdrawn from any suitable intermediate point or plurality of points in this zone and supplied, for example, through line 49 and valve 4|, to pump 42 by means of which they are fed through line 43 and valve 44 to further conversion in conversion conditions. Suflicient heat is supplied to the oil passing'through heating coil 45 to bring it to the desired conversion temperature,

I heated products from heating coil 45 may be utilized to furnish heat for fractional distillation of the charging stock by passing the same through. valve 55 in line 41' and through line l into heat exchanger 6, from which the resulting partially cooled products pass through line I! and valve it! into reaction chamber 29. It will be understood, of course, that all or any desired portion of the heated products from either or both heating coils iii and 45 may be utilized, as described, to supply heat to the charging stock while any remaining portion of either or both of these streams or all of either or both may by-pass heat exchanger 5. It will also be understood that the products. from heating coils l2 and 45 may, when desired, be separately supplied to reaction chamber 29 each at any desired point in this zone, although well known provisions for accomplishing this are not shown in the drawing.

The high boiling fractions of the reflux condensate formed in fractionator 29 may be withdrawn, as illustrated, from the lower portion of this zone through line 49 and valve 50 to pump 5| by means of which they are returned through line 52 and valve 53 to reaction chamber 29. It will be understood that the relatively high boiling oils from column 9 and fractionator 29 may be supplied to reaction chamber 29, separately or in commingled state, at any desired point or plurality of points in this zone, although only one point of introduction is shown in the drawing.

In a process of the character illustrated and above described, the preferred range of operating conditions may be approximately as follows: The temperature to which the charging stock is subjected for the purpose of effecting its fractional distillation may range, for example, from 500 to 800 F., or thereabouts, depending upon its characteristicsthe desired separation to be effect-ed and upon the pressure employed in the fractional distilling stage of the process which pressure may range, for example, from 100 to 500 pounds, or thereabouts, per square inch. The conversion temperature employed at the outlet from the heating coil to which the low boiling fractions of the charging stock are supplied may range, for example, from 900 to 1100 F. and preferably a substantial superatmospheric pressure of the order of 200 to 500 pounds, or more, per square inch is employed at this point of the system although, when desired, lower pressures down to 100 pounds, or less, per square inch may be employed in this zone. the selected relatively low boiling fractions of the intermediate conversion products of the process are supplied may employ an outlet conversion temperature ranging, for example, from 950 to 1050 F., preferably with a substantial sup-cratmospheric pressure, measured at the outlet from the heating coil, of from: 250 to 500 pounds, or more, per square inch. The reaction chamber is preferably operated at a substantial superatmospheric pressure of the order of 100 to 500 pounds, or thereabouts, per square inch, which pressure The heating coil to which may be substantially the same or somewhat lower than that employed in the heating coil utilizing the lowest pressure, in case different pressures are employed in the two heating coils. The vaporizing chamber is preferably operated at a substantially reduced pressure relative to that employed in the reaction chamber which may range, for example, from substantially atmospheric to 100 pounds, or thereabouts, per square inch superatmospheric'. The pressure employed in the vaporizing chamber may be substantially equalized or somewhat reduced in the succeeding, fractionating, condensing and collecting portions of the system.

As a specific example of one of the many possible operations of the process of the present invention utilizing as charging stock a Montana crudeof about 31.8 A. P. I. gravity containing approximately 5% of material boiling up to 215 F. and about 22% boiling up to 400 F. the crude charging stock is heated to a temperature of approximately 650 F. and is subjected to fractional distillation under a. superatmospheric pressure of approximately 500 pounds per square inch. The overhead vaporous products from the fractional distilling operation comprising approximately 35% of the charging stock are subjected in a reforming coil to a conversion temperature of approximately 980 F. at a superatmospheric pressure substantially equalized with that in the fractional distilling stage. The stream of highly heated products from the reforming coil is utilized to furnish heat to the charging stock for its fractional distillation and is then introduced into a reaction chamber maintained at a superatmospheric pressure of approximately 350 pounds per square inch. The high boiling fractions of the charging stock, comprising bottoms from the fractional distilling stage of the process, are also supplied to the reaction chamber. Both vaporous and liquid products are withdrawn from the lower portion of the reaction chamber and introduced into a reduced pressure vaporizing chamber maintained at a superatmospheric pressure of approximately 45 pounds per square inch from which residual liquid is withdrawn while the vaporous products from this zone pass to the fractionator of the cracking system. Selected low-boiling fractions of the reflux condensate from the fractionator of the cracking system having a boiling range of approximately 320 to 600 F. but containing less than 5% of materials boiling below 400 F. are supplied to a separate heating coil wherein theyare subjected to a conversion temperature of approximately 970 F. at a superatmospheric pressure of about 600 pounds. per square inch and the heated products from this zone are discharged into the reaction chamber. The remaining higher boiling fractions of the reflux condensate from the fractionator of the cracking system are returned to the reaction chamber without further heating. This operation may produce, per barrel of charging stock, about 60% of 400 F. end-point motor fuel having an anti-knock value equivalent to an octane number of approximately 70 and about 26% of good quality residual liquid suitable as premium fuel oil, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

1. A process for the fractional distillation and conversion of hydrocarbon oils, which comprises subjecting hydrocarbon oil of relatively wide boiling range to fractional distillation at substantial superatmospheric pressure whereby it is separated into selected relatively low-boiling and high-boiling fractions, withdrawing said lowboiling fractions from the fractional distilling stage in vaporous state and supplying the same, without intentional condensation thereof, to a heating coil wherein they are subjected to conversion conditions of elevated temperature and superatmospheric pressure, introducing the products from said heating coil into an enlarged re action chamber also maintained at superatmospheric pressure and at a conversion temperature, introducing said selected high-boiling fractions of the charging stock into said reaction chamber wherein they are subjected to conversion, withdrawing vaporous and liquid conversion products from the reaction chamber, subjecting the latter to further vaporization at substantially reduced pressure, subjecting the vaporous conversion products of the process to fractionation, whereby their insufliciently converted components are condensed as reflux condensate and separated into selected relatively low-boiling and high-boiling fractions, subjecting the fractionated vapors of the desired end-boiling point to condensation, collecting the resulting distillate, returning said high-boiling fractions of the reflux condensate to the reaction chamber for further conversion, subjecting said selected low-boiling fractions of the reflux condensate to independently controlled conversion conditions of elevated temperature and superatmospheric pressure in a separate heating coil and introducing the heated products from said separate heating coil into the reaction chamber.

2. A process of the character defined in claim 1, wherein regulated quantities of the highly heated products from the first mentioned heating coil are utilized to supply heat for said fractional distillation of the charging stock, by indirect heat exchange therewith, prior to their introduction into the reaction chamber.

3. A process of the character defined in claim 1, wherein regulated quantities of the highly heated products from the last mentioned heating coil are utilized to'supply heat for said fractional distillation of the charging stock, by indirect heat exchange therewith, prior to their introduction into the reaction chamber.

4. A process of the character defined in claim 1, wherein regulated quantities of the highly heated products from both heating coils of the system are utilized to supply heat for said fractional distillation of the charging stock, by indirect heat exchange therewith, prior to their introduction into the reaction chamber.

5. A hydrocarbon oil conversion process which comprises fractionating the charging oil to form a relatively light fraction and a heavier fraction, simultaneously fractionating hydrocarbon vapors independently of the charging oil and separating a relatively light reflux condensate and a heavier reflux condensate therefrom, passing said light fraction and said light reflux condensate through separate heating coils and subjecting the same therein to independently controlled cracking conditions of temperature and pressure, introducing the heated products from said coils into an enlarged reaction zone, introducing said heavier fraction and said heavier reflux condensate, without prior cracking thereof, to the reaction zone, separating the mixture formed in the reaction zone into vapors and residue, fractionating the former as said hydrocarbon vapors, and finally condensing the fractionated vapors.

6. A hydrocarbon oil conversion process which comprises fractionatingthe charging oil to form a relatively light fraction and a heavier fraction, simultaneously fractionating hydrocarbon vapors and separating a relatively light reflux condensate and a heavier reflux condensate therefrom, passing said light fraction and said light reflux condensate through separate heating coils and subjecting the same therein to independently controlled cracking conditions of temperature and pressure, combining said heavier fraction 10 and said heavier reflux condensate, without prior cracking thereof, with the heated products from said coils, passing the resultant mixture through an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing the mixture from the reaction zone and reducing the pressure thereon to separate the same into vapors and residue, fractionating the former as said hydrocarbon vapors, and finally condensing the fractionated vapors.

JACQUE C. MORRELL.

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