US2112377A - Conversion and coking of hydrocarbon oils - Google Patents

Description

March 29, 1938. J. c. MORRELL 2,112,377

CONVERSION AND COKING OF HYDROCARBON OILS Original Filed Oct. 13, 1934 FRACHONATOR FURNACE 42 DISTILLING FURNACE l4 FURNACE 7 INVENTOR JACQUE C. M RRELL.

1 TOR Y Patented Mar. 29, 1938 UNITED STATES ABBON OONVERSIONCAND COK ING OF HYDRO- OILS Jacque C. Morrell, Chicago,-Ill., assignor to Un i-.

vcrsal Oil Products Company, Chicago, 11]., a corporation of Delaware Application ctober' 1a,

1934, Serial No. 748,179 Renewed February 4, 1936 4 Claims. (01.196-49) This invention particularly refers to an improved processfor the fractional distillation of hydrocarbon oils of relativelywide boiling range, such as crude petroleum, for example, accom- 5 panied by the selective conversion of relatively low boiling and high boiling fractions of the charging stock as well as selective conversion of relatively low boiling and high boiling intermediate conversion products of the process and also accompanied by reduction of the residual liquid conversion products of the process to substantially dry coke, assisted by the use of highly heated products resulting from conversion of the relatively low boiling fractionsof the charging stock and of the intermediate conversion products as a heat carrying medium for the coking operation.

As a special feature of the invention, the overhead vaporous products resulting from the fractional distillation of the charging stock are preferably subjected, either alone or together with selected low boiling insuiliciently converted intermediate products of the cracking operation, to conversion or reforming in a heating coil at relatively'high temperature and preferably the overhead products from the distilling operation are supplied to this heating coil while still-in vaporous state without being first subjected to'condensation, which condensation would result in considerable loss of heat, and, in order to obviate the use of a vapor pump for passing the hot vaporous products from the distilling operation through said heating coil, said fractional distillation of the charging stock is preferably accomplished at a pressure sufficiently higher than that employed in the heating coil to overcome the drop in pressure due to friction through the heating coil and succeeding portions of the equipment.

As another feature of the invention, selected high-boiling fractions of the charging stock, comprising, for example, the bottoms from the fractional distilling operation,are preferably subjected to conversion without being passed through a, cracking coil. This is accomplished by supplying said high-boiling fractions from the 45 fractional distilling stage of the process directly to the reaction chamber wherein they commingle with the highly heated products resulting from the conversion of intermediate conversion products of the process and are subjected to continued 50 conversion therewith. This method of operation obviates the difficulties often encountered, due to excessive conversion and coking in the heating coil, when high boiling oils, such as bottoms resulting from the fractional distillation of crude 55 petroleum containing relatively heavy materials of a high coke-forming nature, are supplied to said heating coil for conversion.

As another special feature of the present invention, regulated quantities of the highly heated products from the cracking coil to which the rel- 5 .atively low boiling fractions of the charging stock and, when desired, of the intermediate conversion products of the process are supplied for conversion are'utilized as a heat carrying medium to assist reduction of the residual liquid conversion products of the process to coke by introducing the same into direct contact with the materials undergoing coking in the coking zone.

In the present invention all of the above features are accomplished in a unified system of simpleform and all of the various features are cooperative and mutually contribute to produce the desired final results.

In one specific embodiment, the invention comprises subjecting hydrocarbon oil charging stock of relatively wide boiling range to fractional distillation at substantial superatmospheric pres-.

sure whereby it is separated into relatively low boiling fractions, comprising the overhead vaporous products, and relatively high boiling fractions, comprising condensate or bottoms from the distilling operation, introducing said relatively high boiling fractions into an enlarged reaction chamber also maintained at substantial superatmospheric pressure wherein they commingle with the highly heated products supplied to this zone from a cracking coil of the system, as will be later more fully described, and are sub,- jected to conversion therewith, withdrawing vaporous and liquid conversion products from the reaction chamber and subjecting the latter to coking in a coking chamber operated at substantially reduced pressure, subjecting said'low boiling vaporous fractions of the charging stock from the distilling operation to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil, introducing the highly heated products from the heating coil into direct contact with the materials undergoing coking in the coking chamber whereby to assist the coking 5 operation, subjecting the total vaporous conversion products of the process to fractionation, whereby their insufficiently 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 to condensation, collecting and separating the resulting distillate and gas, subjecting said relatively low boiling fractions of the reflux condensate to further conversion in the same heating coil to which said low boiling vaporous fractions of the charging stock are supplied, subjecting said relatively high 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 stream of highly heated products from said separate heating coil into the reaction chamber to commingle with and effect conversion of said high boiling fractions of the charging stock.

The accompanying diagrammatic drawing illustrates one specific form of apparatus in which the process of the invention may be accomplished.

Referring to the drawing, hydrocarbon oil charging stock for the process, preferably comprising an oil of relatively wide'boiling rangecontaining 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 is fed through line 4 and, in the case here illustrated, is supplied through valve 5 to heating coil 6, wherein it is heated by means of heat supplied from a furnace 'l of any suitable form, preferably at a substantial superatmospheric pressure, to a temperature sumcient to effect its subsequent fractional distillation in column ill, to which it is supplied from heating coil 6 through line 8 and valve 9.

Distilling column i0 is preferably operated at a substantially superatmospheric pressure in order to eliminate pumping of the overhead vaporous products from this zone supplied to cracking coil I3. In the case here illustrated, the charging stock is separated by fractional distillation in column l0 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 ID 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 notdesired 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 anti-knock value, lubricating oil, asphaltic material, etcetera, from the system by well known means (not shown).

The selected low boiling components of the charging stock remaining uncondensed in column III are withdrawn, in the case here illustrated, from the upper portion of this zone through line H to be supplied therefrom through valve l2 to conversion or reforming in heating coil l3.

When desired, a regulated portion of the overhead vaporous product from column [0 may be subjected to condensation, by well known means (not shown), for the purpose of forming distillate which may be utilized as a refluxing medium in column ill by recirculating said distillate to the upper portion of this zone, by well known means (not shown). This is only one of the many well known satisfactory methods which may be employed for assisting fractionation in column l0 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 i3.

In the case here illustrated the high boiling fractions of the charging stock, comprising the bottoms from the fractional distilling operation, are withdrawn from the lower portion of column I 0 through line I! and valve l8 to pump is by means of which they are fed through line 20 and valve 2| and are introduced into reaction chamber 22, to commingle therein with the highly heated products from heating coil 4!, which are supplied to this zone as will be latermore fully described, whereby said high boiling'fractions of the charging stock are heated to a relatively mild conversion temperature and subjected in reaction chamber 22 to conversion, together with the products from heating coil 4|. Pump [9 may, of course, be by-passed by well known ous conversion products from chamber 22 at any desired point 'in this zone above the point of removal of the liquid conversion products, in which case the vaporous products so withdrawn may be separately supplied to coking chamber 25 or to fractionator 30 or in part to'both, as desired. In case a regulated portion or all of the vaporous conversion products from chamber 22 are withdrawn from this zone separate from the residual liquid it is within the scope of the present inven tion to partially cool the same, particularly in case they are supplied to fractionator 30. This cooling may be accomplished by means of a heat exchanger or in any other suitable manner and the heat recovered may be utilized, for example, to preheat the charging stock and effect or assist its fractional distillation, although well known means whereby this particular method of operation maybe accomplished are not shown in the drawing.

Coking chamber 25 is preferably operated at a substantially reduced pressure relative to that employed in reaction chamber 22 although a substantial superatmospheric pressure may be employed in the coking chamber and, when desired, the pressure in the coking zone may be substantially the same or even higher than that employed in the reaction chamber, in which case a pump of any suitable well known form (not shown) is preferably employed in line 23 for transferring the residual liquid from chamber 25. Although only a single coking chamber is shown in the drawing two or more such zones may be employed, when desired, to give additional space for the deposition of coke and they may be either simultaneously operated or, preferably, are alternately operated, cleaned and prepared for further operation in order that the coking stage of the process, in common with the rest of the system, may be operated continuously. The coke formed in chamber 25 is allowed to accumulate within this zone to be removed therefrom, after the operation of the chamber is completed, in any well known manner (not shown). Chamber 25 is provided with a drain-line 26, controlled by valve 21, which may also serve as a means of introducing steam, water or other suitable cooling medium into the chamber after its operation is completed and after it has been isolated from the rest of the system in order to hasten cooling of the chamber and facilitate the removal of coke therefrom.

heating coil H is directed through line 43 and The vaporousproducts from coking chamber 25, including the vapors evolved in this zone by the coking operation as well as any vaporous products supplied thereto from other portions of the system, are directed through line 28 and valve 29 to fractionation in fractionator 30, together with any vaporous products which may be supplied to the fractionator from chamber 22 in the manner perviously indicated. The insuffisired light distillate product which are of in-.

ferior anti-knock value, are condensed in this zone as reflux condensate and preferably, as in the case here illustrated, are separated into selected relatively low boiling and high boiling fractions.

The selected low boiling fractions of the reflux condensate formed in fractionator 30 may be withdrawn from any suitable intermediate point or plurality of points in this zone, for example, through line 3! and valve 32, to pump 33 by means of which they are fed through line 34 and valve 35 into line II, to commingle therein with the low boiling vaporous fractions of the charging stock from column l and be subjected to conversion therewith in heating coil l3. When desired, the low-boiling fractions of the reflux condensate may be preheated, in any well known manner (not shown), prior to their introduction into heating coil l3 and may thereby be supplied to this zone in vaporous state, in common with the low boiling fractions of the charging stock.

Heating coil I3 is located within a furnace l4 of any suitable form which furnishes the Heat required to subject the oils supplied to this zone to the desired relatively high conversion tem-' perature, preferably at a substantial superatmospheric pressure, and the stream of highly heated conversion productsare discharged from this zone through line l and valve l6 into coking chamber 25 wherein they come into direct contact with the materials undergoing coking in this zone and furnish heat for the coking operation. It is, of course, also within the scope of the present invention, although not illustrated in the drawing, to supply only a regulated portion of the stream of highly heated products from heating coil l3 to chamber 25, in which case the remainder may be directed, by well known means (not shown), to reaction chamber 22. It is also within the scope of the invention, although only one point of introduction is illustrated, to supply heated products from chamber [3 to chamber 25 at any desired pointor plurality of points in this zone.

The relatively high boiling fractions of the reflux condensate formed in fractionator 30, or the total reflux condensate, in case no separation of densation and cooling in condenser 41.

valve 44 into reaction chamber 22, to commingle therein with the high boilingfractions of the charging stock supplied to this zone, as previously described. Y

Chamber 22 is preferably maintained at a substantial superatmospheric pressure, which may be substantially the same or somewhat lower than that employed at the outlet from heating coil 4i, and, although not illustrated in the drawing, chamber 22 is preferably insulated against the excessive loss of heat' so that continued conversion of the products from heating coil 4| and conversion of the high boiling fractions of the charging stock supplied to this zone may be accomplished therein.

Fractionated vapors of the desired end boiling point, preferably comprising materials within the boiling range of motor fuel and of good antiknock characteristics, are withdrawn, together withuncondensable gas produced by the process, from. the upper portion of fractionator 30 through line 45 and valve 46 and are subjected to con- The resulting distillate and gas passes through line 48 and valve 49 to collection and separation in receiver 50. Uncondensable gas may be released from the receiver through line 5| and valve 52. Distillate is withdrawn from receiver 50 through line 53 and valve 54 to storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 50 may be recirculated by well known means (not shown) to the upper portion of fractionator 33 to assist fractionation of the vapors in this zone and to maintain the desired vapor outlet temperature from the fractionator.

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 mayrange, for example, from 500 to 800 F or thereabouts, depending upon its characteristics, the desired separation to be effected and 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 total reflux condensate from the fractionator of the system or only the high boiling fractions of the reflux condensate are supplied may range, for example, from 875 to 975 F., preferably with a substantial super-.

atmospheric pressure, measured at the outlet from the heating coil, of from 100 to 500 pounds, or thereabouts, per square inch. Substantially the same or somewhat lower superatmospheric pressure may be employed in the reaction chamber. The heating coil to which the low boiling vaporous fractions of the charging stock from the distilling operation are supplied, either alone or together with selected low boiling fractions of the reflux condensate, may range, for example, from 900 to 1100" F., preferably with a substantial superatmospheric pressure at this point in the system of from 200 to 500 pounds, or more,

for example, from 100 pounds. or thereabouts,"

per square inch down to substantially atmospheric pressure although, when desired, higher pressures up to or even higher than that employed in the reaction chamber, but preferably no higher than the pressure employed in heating coil is, may be utilized in the coking zone. The pressures employed in the fractionating, condensing and collecting portions of the system may be substantially the same or somewhat lower than the pressure employed in the coking zone.

As a specific example of one of the many possible operations of the process of the present invention as it may be accomplished in an apparatus of the character illustrated and above described, utilizing as charging stock a Wyoming crude of about 27 A. P. I. gravity containing less than 5% of material boiling up to 250 F.; the charging stock is heated to a temperature of approximately 750" F. at a superatmospheric pressure of about 200 pounds per square inch. The overhead stream of vaporous products from the distilling operation, which is removed from the distilling column at a temperature of approximately 575 F., is subjected, together with a selected low boiling fraction of the reflux condensate from the fractionator of the system, having a boiling range of approximately 350 to 600 F., in a heating coil, to an outlet conversion temperature of approximately 1000 F. with a pressure in this zone substantially equalized with that in the distilling column. The highly heated products from this heating coil are introduced into a coking chamber where they come into contact with the residual liquid withdrawn from the reaction chamber of the system and effect its reduction to coke. The remaining portion of the reflux condensate from the fractionator of the system, comprising its high boilingcomponents, are subjected in a separate heating coil to an outlet conversion temperature of approximately 950 F. at a superatmospheric pressure of about 300 pounds per square inch and the heated products are introduced to the reaction chamber, which is maintained at substantially the same pressure, wherein they commingle with and effect conversion of the high boiling fractions of the charging stock from the distilling operation. This operation will produce, per barrel of charging stock, approximately 60% of 400 F. endpoint motor fuel having an anti-knock value equivalent to an octane number of approximately 70, about 65 pounds of low volatile coke and approximately 1250 cubic feet of rich uncondensable gas.

I claim as my invention:

1. In a process for the fractional distillation and pyrolytic conversion of hydrocarbon oils wherein intermediate conversion products of the process are subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating enlarged reaction'chamber, vaporous and residual liquid conversion products withdrawn from the reaction chamber, the latter subjected to coking in a coking chamber, vaporous conversion products of the process, including those from the coking zone, subjected to fractionation, whereby their insufliciently converted components are condensed as reflux condensate, fractionated vapors of the desired end boiling point subjected to condensation, the resulting distillate collected and reflux condensate from the fractionator of the system, comprising said intermediate conversion products of the process, returned to the heating coil for further conversion, the improvement which comprises subjecting hydrocarbon oil charging stock for the process, comprising an 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 -low boiling fractions from the fractional distilling stage in vaporous state and supplying the same without intentional condensation thereofto a separate heating coil wherein they are subjected to conversion conditions of elevated temperature and superatmospheric pressure, introducing the highly heated products from said separate heating coil into direct contact withthe materials undergoing coking in the coking chamber for the purpose of assisting their reduction to coke and supplying said selected high boiling fractions of the charging stock from the fractional distilling stage to the reaction chamber wherein they commingle with and are subjected to conversion together with the products from the first mentioned heating coil.

2. In a process for the fractional distillation and pyrolytic conversion of hydrocarbon oils wherein intermediate conversion products of the process are subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, vaporous and residual liquid conversion products withdrawn from the reaction chamber, the-latter subjected to coking in a reduced pressure coking chamber, vaporous conversion products of the process, including those from the coking zone, subjected to fractionation, whereby their insumclently converted components are condensed as reflux condensate, fractionated vapors of the desired end boiling point subjected to condensation, the resulting distillate collected and reflux condensate from the fractionator of the system, comprising said intermediate conversion products of the process, returned to the heating coil for further conversion, the improvement which comprises subjecting hydrocarbon oil charging stock for the process, comprising an oil of relatively wide boiling range, to fractional distillation whereby it is separated into selected relatively low boiling and high boiling fractions, withdrawing said low boiling fractions from the fractional distilling stage in vaporous state and supplying the same, without intentional condensation thereof, to a separate heating coil wherein they are subjected to pyrolytic conversion, introducing the highly heated products from said separate heating coil into direct contact with the materials undergoing coking in the coking chamber for the purpose of assisting their reduction to coke and supplying said selected high boiling fractions of the charging stock from the fractional distilling stage to the reaction chamber, wherein they commingle with and are subjected to conversion together with the products from the first mentioned heating coil.

3. In a process for the fractional distillation and pyrolytic conversion of hydrocarbon oils wherein intermediate conversion products of the process are subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, vaporous and residual liquid conversion products withdrawn from the reaction chamber, the latter subjected to coking in a coking chamber, vaporous conversion products of the process, including those from the coking zone, subjected to fractionation, whereby their insufficiently converted components are condensed as reflux condensate and separated into selected relatively low boiling and high bolling fractions, fractionated vapors of the desired end boiling point subjected to condensation, the resulting distillate collected and said high boiling fractions of the reflux condensate from the fractionator of the system, comprising said intermediate conversion products of the process, returned to the heating coil for further conversion, the improvement which comprises subjecting hydrocarbon oil charging stock for the process, comprising an oil of relatively wide boiling range, to fractional distillation at substantial superatmospheric pressure whereby it is sepa rated into selected relatively low boiling and high boiling fractions, withdrawing said low boiling fractions from the fractional distilling stage in vaporous state and supplying the same, without intentional condensation thereof, to a separate heating coil wherein they are subjected to conversion conditions of elevated temperature and superatmospheric pressure, returning said selected low boiling fractions of the reflux condensate to said separate heating coil. for further conversion, introducing the highly heated products from said separate heating coil into direct contact with the materials undergoing coking in the coking chamber for the purpose of assisting their reduction to coke and supplying said selected high boiling fractions of the charging stock from the fractional distilling stage to the reaction chamber wherein they commingle with and are subjected to conversion together with the products from the first mentioned heating coil.

4. In a process for the fractional distillation and pyrolytic conversion of hydrocarbon oils wherein intermediate conversion products of the process are subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, vaporous and residual liquid conversion products withdrawn from the reaction chamber, the latter subjected to coking in a reduced pressure coking chamber, vaporous conversion products of the process, including those from the coking zone, subjected to fractionation, whereby their insufficiently converted components are condensed as reflux condensate and separated into selected relatively low boiling and high boiling fractions, fractionated vapors of the desired end boiling point subjected to condensation, the resulting distillate collected and said high boiling fractions of the reflux condensate from the fractionator of the system, comprising said intermediate conversion products of the process, returned to the heating coil for further conversion, the improvement which comprises subjecting hydrocarbon oil charging stock for the process, comprising an oil of relatively wide boiling range, to fractional distillation whereby it is separated into selected relatively low boiling and high boiling fractions, withdrawing said low boiling fractions from the fractional distilling stage in vaporous state and supplying the same, without intentional condensation thereof to a separate heating coil wherein they are subjected to pyrolytic conversion, returning said selected low boiling fractions of the reflux condensate to said separate heating coil for further conversion, introducing the highly heated products from said separate heatingcoil into direct contact with the materials undergoing coking in the coking chamber for the purpose of assisting their reduction to coke and supplying said selected high boiling fractions of the charging stock from the fractional distilling stage to the reaction chamber wherein they commingle with and are subjected to conversion together with the products from the first mentioned heating coil.

JACQUE C. MORRELL.

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