US2143894A - Conversion of hydrocarbon oils - Google Patents

Description

Jan '17, B939. J. c. MORRELL 2,143,39

CONVERSION OF HYDROCARBON OILS Filed Nov. 26, 1934 FURNACE l5 FURNACE 7; r

DlSTILLlNG AND FRACTIONATENG COLUMN FURNACE s4 STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Jacque C. Morrell, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application November 26, 1934, Serial No. 754,793

1 Claim. (01. 196-49) This invention refers to an improved process the fractional distillation of the charging stock for the fractional distillation of hydrocarbon oils are supp preferably While Still in at d Veof relatively wide boiling range, such as crude D O State, to a heating Coil wherein y a petroleum, for example, accompanied by the subjected to Conversion reforming at e pyrolytic conversion, under independently contively high temperature, Without fi subjecting 5 trolled conditions, of the overhead v p rous the same to condensation, which would result in products and the bottoms from the distilling Opa considerable loss of heat, and in order to obvieration as well as selective further conversion, a the use Of a Vapor p to P e hot Vawithin the same system, of relatively low-boiling 1 0 products from the topping Operation and high-boiling intermediate products of the t r u sa d h a n coil, t t ppin p ati n 10 process and accompanied by reduction of the S p e y cendlleted at a pressure Sllfficiently residual liquid conversion products to coke. higher than that p e in e a g CO The present invention offers a simple nd i to overcome the drop in pressure, due to friction fied system for the fractional distillation of hyr u h t at 1 a su d n p rt ns drocar'bon oils of relatively wide boiling range of the system. I

accompanied by the selective conversion of relain One Specific embodiment, the ve io tively, low-boiling and relatively high-boiling comprises subjecting hy a Oil Charging fractions of the charging stock as well as relative- StOek for the p Comprising an Oil f elaly low-boiling and high-boiling fractions of the tiVelY Wide boiling g t a t na distillaintermediate conversion products of the process. tiOn at Substantial supeietmospherie P ure 20 Selected relatively low-boiling fractions of the whereby to Separate the Same into relatively wcharging stock and selected relatively low-boilboiling fractions, Comprising the Overhead V p ing fractions of the intermediate conversion s products, and relatively high-boiling fra products of the process are each subjected to inthine, celnprising Condensate 0 b tto s from dependently controled conversion conditions of the distilling Operathm, j t g Said low-boil- 25 elev ted t m t r and superatmospherjc ing vaporous fractions to conversion conditions pressure in a separate heating coil, the stream of elevated temperature and Superetmospherie of heated products from one of said heating pressure in heating i introducing t e S ream coils being directed to an enlarged reaction of highly heated products from Said heating Coil chamber maintained at superatmospheric presihtO an enlarged reaction a er e150 main- 30 sure, to which said selected high-boiling fractions tallied at superatmospheric p su e a d Comof th ch r i t k d high-boiling fra tion mingling therewith said high-boiling fractions of of the reflux condensate are directly supplied, the Charging Sto k, W thdrawing both vaporous whereby said relatively high-boiling fractions and liquid conversion products from the reaction are heated by commingling with the highly he tchamber and subjecting the latter to coking in a 35 ed relatively low-boiling oils and subjected in the reduced pressure Coking C amber subjectin the reaction chamber to less severe conversion con- VepOrOuS Conversion products, including thOSe ditions than those to which the relatively lowevolved in the coking operation, t ra t onation, boiling oils are subjected. The stream of highly whereby their insumciehtly Converted co poheated products from the other heating coil are nents are condensed as reflux condensate an 40 introduced into direct contact in a low-pressure separated into selected relatively -b l g and vaporizing, cracking and/or coking zone th high-boiling fractions, subjecting the resulting residual liquid conversion products withdrawn fractionated Vapors 0f the desired end-boiling from said reaction chamber. The vaporous conp nt t d at collecting a s para in 5 version products of the process, including those the resulting distillate and returning Said evolved by reduction of the residual liquids to relatively high-boiling c ns of the reflux coke, are subjected to fractionation for the forcondensate to the reaction chamber for further mation of said reflux condensate and fractionconversion, subjec g the relettively -bo n at-ed vapors of the desired end-boiling point, fractions of the reflux condensate to independpreferably comprising materials within the ently controlled conversion conditions of ele- 50 boiling range of motor fuel of good antiknock vated temperature and superatmospheric presvalue, are subjected to condensation and the resure in a separate heating coil and introducing sulting distillate and gas collected and separated. the heated products from said separate heating As a special feature of the present invention, coil into direct contact with the materials underthe overhead vaporous products resulting from going coking in the coking chamber. 55

As an alternative to the specific method of operation above described which, however, is not to be considered equivalent, the low-boiling fractions of the charging stock, comprising the overhead vaporous product from the distilling operation, may be subjected to conversion in said separate heating coil and utilized as a heat carrying medium for the coking operation, in which case the selected-relatively low-boiling fractions of the reflux condensate are supplied through the first mentioned heating coil into the reaction chamber.

The accompanying diagrammatic drawing illustrates one specific form of apparatus for carrying out the invention. It will be noted that the various features of the invention are cooperative and mutually contribute to produce the desired final results. It should also 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, such as crude petroleum, for example, containing an appreciable quantity of both relatively low-boiling and relatively high-boiling components, is supplied through line I and valve 2 to pump 3 by means of which it may be directed through line t and valve 5 to heating coil 6. The charging stock is subjected in the heating coil, by means of heat supplied from a furnace I of any suitable form, to a temperature sufficient to effect its subsequent fractional distillation in distilling and fractionating column ID to which it is supplied from the heating coil through line 3 and valve 9. It is, of course, within the scope of the present invention to preheat the charging stock in any suitable well known manner, not illustrated, prior to its introduction into heating coil 6 or to supply a portion or all of the heat required for fractional distillation of the charging stock thereto by indirect heat exchange between the charging stock and hot vaporous and/or liquid products of the process or by means of heat recovered from within the system in any other suitable manner, although means for accomplishing this are not illustrated in the drawing.

Distilling column ID is preferably operated at a substantial superatmospheric pressure in order to eliminate pumping of the overhead vaporous products from this zone supplied to the cracking coil. In case here illustrated, the charging stock is separated by fractional distillation in column It 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 IE] 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 lowboiling, 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, Diesel fuel, furnace oil, lubricating oil, asphaltic material, etc. from system by well known means, not illustrated in the drawing.

The selected low-boiling components of the charging stock remaining unvaporized in column iii are withdrawn, in the case here illustrated from the upper portion of this zone through line H and valve l2 to be supplied therefrom through line E3 to conversion or reforming in heating coil It.

When desired, a regulated portion of the overhead vaporous product from column l0 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 It 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 Ill 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 H1 is located within a furnace 15 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 M is also preferably operated at a substantial superatmospheric pressure and the highly heated products are discharged from this zone through line it and Valve ll into reaction chamber l8.

In the case here illustrated the high-boiling fractions of the charging stock withdrawn from the lower portion of column Ill through line l9 and valve 20 to pump 2! are fed therefrom through line 22 and valve 23 into reaction chamber 58.

Reaction chamber I8 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 50 that conversion of the various oils supplied to this zone, and particularly their vaporous components, may continue therein. The heat contained in the products supplied from heating coil I4 to reaction chamber 18 to heat the higher boiling oils supplied to this zone and effect their appreciable conversion therein at a temperature somewhat lower than the temperature employed in the heating coil. In the particular case here illustrated both vaporous and liquid conversion products may be withdrawn from the lower portion of chamber i8 through line 24 and valve 25 and are introduced into coking chamber 26. Preferably, however, a major portion or all of the vaporous conversion products are separately withdrawn from the reaction chamber at any desired point above the point of removal of the liquid conversion products from this zone, being directed, in the case here illustrated, through line 21 and valve 28 to fractionation in fractionator 29.

vaporous products from coking chamber 26 are also supplied, in the case here illustrated, through line 30 and valve 3| to fractionation in fractionator Z9 and the insuificiently converted components of the vaporous products supplied to this zone, boiling above the range of the desired final light distillate product of the process, are condensed within the fractionator as reflux condensate and separated into selected relatively low-boiling and high-boiling fractions.

Fractionated Vapors of the desired end-boiling point are withdrawn, together with uncondensable gas, from the upper portion of fractionator 29 through line 32 and valve 33 and are subjected to condensation and cooling in condenser 34. The resulting distillate and gas passes through line 35 and valve 36 to collection and separation in receiver 31. Uncondensable gas may be released from the receiver through line 38 and valve 39. Distillate may be withdrawn from receiver 31 through line 4!] and valve 4! to storage or to any desired further treatment. A regulated portion of the distillate collected in receiver 37 may, when desired, be recirculated, by well known means, not illustrated, to the upper portion of fractionator 29 to serve as a cooling and refluxing medium for assisting fractionation of the vapors and to maintain the desired vapor outlet temperature from the fractionator.

High-boiling fractions of the reflux condensate formed in fractionator 29 are withdrawn from the lower portion thereof through line 42 and valve 43 to pump M by means of which they are fed through line 45 and valve 66 into line 22 to commingle therein with the high-boiling fractions of the charging stock and be directed therewith to reaction chamber [8 for further conversion.

Selected low-boiling fractions of the reflux condensate formed in fractionator 29 may be withdrawn from any suit-able intermediate point or plurality of points in this zone such as, for example, through line ti and are directed through valve 68 to pump it by means of which they are fed through line 50 and may be directed therefrom through line 51 and valve 52 to further conversion in heating coil 53.

Heating coil 53 is located within a furnace of any suitable form, by means of which the required heat is supplied to the oil passing through the heating coil to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure, and the stream of highly heated products are discharged from heating coil 53 through line 55 and valve 5% into coking chamber 25; preferably being directly commingled in this zone with the materials undergoing coking, whereby to supply additional heat thereto and assist the coking operation.

Coking chamber 26 is preferably operated at a substantially reduced pressure relative to that employed in reaction chamber 48. When desired, a plurality of coking chambers similar to chamber 26 may be employed, although not illustrated, in order to provide additional space for the deposition of coke, in which case the coking chambers preferably are alternately operated, cleaned and prepared for further operation so that the duration of the operating cycle of the process will not be limited by the capacity of the coking chambers. Coke is allowed to accumulate within chamber 26 from which it may be removed in any suitable well known manner, not illustrated, after the operation of the chamber has been completed and after it has been isolated from the rest of the system. Chamber 26 is provided with a drain-line 5'5 controlled by valve 53 which may also serve as a means of introducing water, steam or other suitable cooling medium into the coking chamber after it has been isolated from the rest of the system in order to fasten cooling and facilitate cleaning of the chamber.

It is also within the scope of the present invention as an alternative method of operation to that above described to subject the selected lowboiling fractions of the charging stock, comprising the overhead vaporous product from distilling and fractionating column 10, to conversion in heating coil 53. This may be accomplished, for example, by diverting the vaporous products from line If through line 59 and valve 6|] into line 5i and thence to heating coil 53. When this method of operation is employed the low-boiling fractions of the charging stock, instead of the selected lowboiling fractions of the reflux condensate, serve as a heat carrying medium for the coking operation and said selected low-boiling fractions of the reflux condensate, instead of being supplied to heating coil 53, are directed to heating coil M for further conversion, by means of line 6| valve 52 and line 13. When this alternative method of operation is employed it is within the scope of the invention to employ substantially atmospheric or a relatively low superatmospheric pressure at the outlet from heating coil 53 and in coking chamber 26, in which case the pressure employed in column I0, wherein the charging stock is subjected to fractional distillation, may be only sufficient to overcome the drop in pressure through the heating coil and communicating lines, due to friction.

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 characteristics, the desired separation to be effected and upon the pressure employed in the fractional distilling stage of the process which 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 pressure down to 100 pounds, or less, per square inch may be employed in this zone. The heating coil to which the selected relatively low-boiling fractions of the intermediate conversion products of the process are supplied may employ an outlet conversion temperature range, for example, from 950 to 1050 F., preferably with a substantial superatmospheric pressure, measured at the outlet from the heating coil, of from 200 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. The coking 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, although, when desired, higher pressure may be employed in this zone. The fractionating condensing and collecting portions of the cracking system may employ pressures substantially the same or somewhat lower than that employed in the coking chamber.

As a specific example of one of the many pos sible operations of the process of the present invention, utilizing as charging stock a Montana crude of about 31.8 A. P. I. gravity containing approximately 5 percent of material boiling up to 215 F. and about 22 percent boiling up to 400 F.: the crude charging stock is heated to a temperature of approximately '750 F. and is subjected to fractional distillation under a superatmospheric pressure of approximately 500 pounds per square 7 inch. The overhead vaporous products from the fractional distilling operation comprising approximately 35 percent of the charging stock, are subjected in a reforming coil to a conversion temperature of approximately 1000 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 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. Liquid conversion products are Withdrawn from the reaction chamber and introduced into alternately operated coking chambers maintained at a superatmospheric pressure of approximately 30 pounds per square inch. The vaporous products from the coking chamber and from the reaction chamber are subjected to fractionation and the reflux condensate thus formed is separated into selected relatively high-boiling and low-boiling fractions. The high-boiling fractions of the reflux condensate are returned to the reaction chamber together with the high-boiling fractions of the charging stock. The selected low-boiling fractions of the reflux condensate, having a boiling range of approximately 309 to 550 F. but containing less than percent of material boiling below 385 F., are subjected in a separate heating coil to an outlet conversion temperature of approximately 975 F. at a superatmospheric pressure of about 500 pounds per square inch and the stream of highly heated products from this zone discharged into the alternately operated coking chambers. This operation will produce, per barrel of charging stock, approximately 65 percent of motor fuel having an antiknock value equivalent to an octane number of approximately 72 and approximately '76 pounds of relatively dry coke, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

A hydrocarbon oil conversion process which comprises introducing the charging oil to a vaporizing zone and therein vaporizing a portion 7 thereof, passing vaporized portions of the oil through a heating coil and subjecting the same therein to cracking conditions of temperature and pressure, removing unvaporized oil from the vaporizing zone and commingling the same with the hot conversion products from the coil, separating the resultant mixture into vapors and residual oil in a separating zone and fractionating the former to separate relatively heavy and light reflux condensates therefrom, commingling the heavier reflux condensate with said hot conversion products from the coil, subjecting the lighter reflux condensate to independently controlled cracking conditions in a second heating coil and then contacting the same with said residual oil a distilling zone maintained under lower pressure than said separating zone, mixing vapors from the distilling zone with the vapors from the separating zone for fractionation therewith,

finally condensing the fractionated vapors. JACQUE C. MORRELL.

Images