US2098033A - Conversion and coking of hydrocarbons - Google Patents

Description

Nov. 2, 1937. A. FISHER 2,093,033

CONVERSION AND COKING OF HYDROCARBONS Filed June 2, 1933 RECEIVER FURNACE RECEIVER l INVENTOR ALFRE FISHER BY ATTORNEY COKING OVEN 23 Patented Nov. 2, 1937 CONVERSION AND COKING F HYDROCARBONS Alfred Fisher, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application June 2, 1933, Serial No. 674,001

9 Claims.

This invention particularly refers to an improved process and apparatus for the conversion and coking of mixtures of hydrocarbon oil and solid or semi-solid carboneaceous material such as coal, peat, lignite, oil shale and the like wherein intermediate liquid products of the process are subjected to further conversion under independently controlled more severe conversion conditions in the same system while the heavy liquid products of the conversion and coking operations are returned for further treatment with the charging stock.

One specific embodiment of the present invention may comprise subjecting a mixture of hydrocarbon oil and finely divided carbonaceous material to mild conversion in a heating coil under non-coking conditions, introducing the .heated material into a plurality of alternately operated coking ovens wherein the residual conversion products are reduced to coke and the coke is substantially devolatiliz-ed by introducing the oil onto a highly heated surface, subjecting the vaporous products from the coking ovens to fractionation whereby they are separated into fractionated vapors of the desired end-boiling point, intermediate condensate and higher boiling liquid products including tars and similar high coke-forming materials, returning the latter to further treatment, together with the charging stock, subjecting the fractionated vapors to condensation, collecting and separating the resulting distillate and gas, subjecting the intermediate condensate to further conversion under independently controlled more severe con version conditions, separating the resulting vaporous and residual liquid conversion products, returning the latter to further treatment, together with .the charging stock, subjecting the =vdpor'ous conversion products to fractionation whereby their insumciently -converted components are condensed as reflux condensate, returning reflux condensate to further treatment, together with said intermediate condensate from the first described cracking and coking operation, subjecting the fractionated vaporous conversion products of the desired end-boiling point to condensation and collecting and separating the resulting distillate and gas.

The features and advantages of the present invention will be more apparent with reference to the accompanying diagrammatic drawing which illustrates one specific form of apparatus in which the process of the present invention may be accomplished. The drawing and the following description thereof embodies several m ldlfications of the specific embodiment of the invention above described which are within the scope of the present invention.

Referring to the drawing, raw oil charging stock, comprising any desired hydrocarbon oil such as crude petroleum, petroleum residue, fuel oil or the like, includingsuch oils as coal tar, pitches and other heavy oils, is supplied through line I and valve 2 to pump 3 by means of which it is fed through line 4 and valve 5 into mixing tank 6 wherein it may be commingled and intimately mixed with other ingredients of the combined feed for the process. Coal or other suitable solid or semi-solid carbonaceous material is added to the mixing tank, preferably in finely divided form and in regulated amounts relative to the raw oil, through a hopper or other suitable charging device 1 of any suitable form. Mixing tank 6 is preferably equipped with a. stirring device 8 of any suitable form by means of which the carbonaceous material is finely dispersed throughout the body of the oil and the ingredients of the combined feed are maintained in a thoroughly commingled state. Other oils from within the system may be added to the materials in the mixing tank to make up the total combined feed for the process, as will be later more fully described, and the commingled materials are withdrawn from the mixing tank through line 9 and valve Ill to pump II by means of which they are fed through line l2 and valve l3 to heating coil I 4. When the charging stock is of a heavy viscous nature it may be necessary to heat the liquid charging stock and/or the combined feed by means of steam jacketed lines or a steam jacketed mixing tank or in any other suitable well known manner, not illustrated in the drawing, in order to facilitate the handling of this material. When desired, heat for this purpose may be recovered from within the system by means of heat exchangers or the like, not illustrated in the drawing. I

Heating coil I4 is located within a furnace l5 of any suitable form by means of which the combined feed passing therethrough is heated quickly to the desired conversion temperature, preferably at a substantial superatmospheric pressure, without allowing sufiicient conversion time in the heating coil to cause any detrimental formation and deposition of coke in this zone, a high rate of heating being maintained in furnace l5 and a high oil velocity being maintained through heating coil II for this purpose. The heated materials pass from heating coil l4 t l l gh line l6 and valve i! and are introduced into the coking oven 23, through lines 24, 24' and 24", controlled by the respective valves, 25, 25' and 25".

Coking oven 23 preferably comprises a plurality of coking chambers 26, 26' and 26" which may be alternately operated, cleaned and prepared for further operation in order to render the process continuous. It will be understood that any number of similar coking chambers may be employed, although only three are illustrated in the drawing. Each. of the coking chambers has a floor 21, preferably constructed of suitable refractory high heat conductive material such as silicon carbide, fused aluminum oxide, aluminum silicate and the like, heated to a high temperature from beneath by means of the combustion of any suitable type of fuel in combustion zones 28. The heated oil from heating coil I4 is directed onto the highly heated floor of one or more of the coking chambers whereby the oil is coked and the coke is allowed to accumulate in a relatively thin layer to a depth of approximately 6 inches' or less over the highly heated floor, following which heating may when desired be continued for a time to devolatilize the coke to the desired degree, during which the oil is diverted to another coking chamber, and finally the layer of devolatilized coke is removed, by means of an hydraulic ram or in any other suitable well known manner, following which the chamber is prepared for further operation. vaporous products are withdrawn from the coking chambers through lines 29, 29' and 29" controlled by valves 38, 30' and 30", respectively, and pass into fractionator 3| which, in the case here illustrated, also serves as a vaporizing and tar separating zone.

The vaporous products supplied to fractionator 3| may be separated into three major components comprising light fractionated vapors of the desired end-boiling point, intermediate condensates and higher boiling liquids, the latter including any tars or similar high coke-forming materials or, when desired, the total reflux condensate comprising the intermediate condensates and higher boiling liquids may be recovered without dividing it into low-boiling and high-boiling fractions.

Fractionated vapors of the desired end-boiling point pass from the upper portion of fractionator 3| through line 31 and valve 38 to condenser 39 wherein they are subjected to condensation and cooling and from which the resulting distillate and gas passes through line 40 and valve 4| to collection and separation in receiver 42. Uncondensable gas may be released from the receiver through line 43 and valve 44. Distillate may be withdrawn from this zone to storage or to any desired further treatment through line 45 and valve 46.

It is Within the scope of the present invention to employ substantially atmospheric, subatmospheric or a low superatniospheric pressure in the coking oven. In case sub atmospheric pressure is employed in this zone it is also preferably employed in the succeeding fractionating, condensing and collecting equipment of this portion of the system, in order to avoid pumping or compression of the vaporous products from the coking oven at high temperature, the sub-atmospheric pressure being controlled by means of a vacuum pump 49 which withdraws gas from receiver 42 thorugh line 41 and valve 48, discharging it through line 58 and valve from which it may pass through suitable scrubbing equipment, not shown, or direct to a gas holder, not ShOWn, or elsewhere, as desired.

When intermediate condensates are recovered from fractionator 3| this material which is of a higher boiling nature than the overhead vaporous product from the fractionator and of lower boiling nature than the high coke-forming liquids removed from the lower portion of the fractionator may be withdrawn as one or a plurality of side streams from the fractionator,for example, through line 52 and valve 53 to pump 54 by means of which these intermediate fractions are fed through line 55 and valve 56 and may pass, all or in part, either through valve 51 in this line into fractionator, 58 or, all or in part, from line 55 through line 59, valve 60 and line 65 into heating coil 18. It will be understood that, when desired, the intermediate condensate from fractionator 3| may be subjected to reboiling in a suitable side stripper column or in any well known manner, not illustrated, in order to free it of entrained gas and/or desirable low-boiling fractions within the range of the overhead product from fractionator 3|.

Depending upon the method of the operation chosen, the liquid withdrawn from the lower portion of fractionator 3| through line 32 and valve 33 to pump 34 may comprise the total condensate removed from the vapors by fractionation in this zone or only its high-boiling fractions including tars and similar high coke-forming materials. In either case this material is fed by means of pump 34 through line 35 and may pass, all or in part, either through line 36, valve 59, line 55 and valve 51 into fractionator 58 or through line 1|, valve 12 and line I2 to heating coil H for further conversion together with the charging stock or, when desired, instead of passing direct to heating coil H the oil from line 1| may pass through line 13 and valve 14 into mixing tank 6 to commingle therein with the charging stock mixture, prior to its passage to heating coil l4.

The condensate supplied from fractionator3| to fractionator 58 comprises either all or a portion of the total liquids recovered from the vapors in fractionator 3| or a portion or all of only the intermediate condensates from fractionator 3|, as already described. This material serves as a refluxing medium to assist fractionation of the vaporous conversion products supplied to fractionator 58, as will be later more fully described, and, when desired, the oil may be cooled to any desired degree, prior to its introduction into fractionator 58 by well known means, not shown in the drawing. The total material supplied to fractionator 58, including both vaporous conversion products and liquid from fractionator 3|, may be separated, after the removal of low-boiling vaporous products comprising the overhead stream from the fractionator, into low-boiling and high-boiling condensate fractions or, when desired, the total liquid recovered from the materials supplied to fractionator 58 may be removed therefrom without separation. In the latter case this material is withdrawn from the lower portion of fractionator 58 through line BI and valve 62 to pump 63 by means of which it is fed through line 64, line 65 and valve 66 to further conversion in heating coil 18. Preferably this method of operation is not employed except when only intermediate condensates from fractionator 3| are supplied to fractionator 58 in order to avoid the return of any tars or similar high coke-forming materials from fractionator 3| to heating coil 10.

In case only high-boiling fractions of the liquid recovered from fractionator 58 are supplied to pump 63 this material is preferably returned through line 64, line 81, valve 68 and line I2 to heating coil I4 for further conversion or it may be diverted, all or in part, from line 61 through line 15 and valve I6 into mixing tank 6 to com-- mingle with the charging stock mixture, prior to its introduction into heating coil I4.

When low-boiling fractions of the liquids recovered from fractionator 58 are separated from the higher boiling fractions in this zone they may be removed from the fractionator as one or a plurality of side streams, for example, through line I1 and valve 18 to pump I9, being reboiled, when desired, by well known means, not shown in the drawing, for the purpose of freeing this material from entrained gases and any low-boiling fractions within the range of the desired overhead product from fractionator 58. The lowboiling oils thus supplied to pump -Iil are returned through line 88, valve BI, line 59 and line to further conversion in heating coil 18.

A furnace 82 of any suitable for'm, enclosing heating coil I8, supplies the required heat to the oil passing therethrough to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure, and the heated oil is discharged through line 83 and valve 84 into reaction chamber 85.

Chamber 85 is also preferably maintained at a substantial superatmospheric pressure and, although not illustrated in the drawing, is preferably well insulated to prevent the excessive loss of heat therefrom so that conversion of the heated oil from heating coil I8, and particularly its vaporous components, may continue in this zone. In the case here illustrated, both vaporous and liquid conversion products are' withdrawn from the lower portion of chamber 85 through line 88 and valve 81 and are introduced into vaporizing and separating chamber 88.

Chamber 88 is preferably operated at a substantially reduced pressure relative to that employed in chamber 85, by means of which further vaporization of the liquid conversion products supplied to this zone is accomplished. Rough fractionating means, for example, such as baflles indicated at 88, may be employed, when desired, in the upper portion-of chamber 88 for the purpose of removing entrained heavy liquids from the vaporous conversion products, prior to their introduction into fractionator 58.

Residual liquid conversion products remaining unvaporized in chamber 88 are withdrawn therefrom through line 98 and valve 9| to pump 92, by means of which they may be returned through line 93, valve 94 and line I2 to heating coil I4 or they may pass, all or in part, through line 95 and valve 96 into mixing tank 8, to commingle therein with the other materials supplied to this zone and form a component of the combined feed supplied, as already described, to heating coil I4.

When liquids are supplied from within the system, as already described, to mixing tank 6 they may, when desired, be cooled by well known means, not shown in the drawing, prior to their introduction into this zone. However, when it is desired to conserve the heat remaining in these products and in case it is not desirable to supply them direct to heating coil I4, as has been previously described, mixing tank 6 may be operated at substantial super-atmospheric pressure in order to minimize vaporization in this zone and is preferably well insulated to conserve heat or may be provided with a suitable steam jacket, not shown. In case the mixing tank is operated at superatmospheric pressure a suitable valve 81 may be provided beneath hopper I and the tank is preferably provided with a vent 88 controlled by valve 89 through which any incidental vapors evolved from the hot material in the mixing tank may pass to thefractionator or elsewhere, as desired.

Vaporous conversion products pass from vaporizing chamber 88 through line I88 and valve IN to fractionation in fractionator 58, wherein their insufficiently converted components are condensed as reflux condensate, to be returned, as already described, to heating coil I8 for further conversion or separated ,into low-boiling and high-boiling fractions, together with the condensate supplied to this zone from fractlonator 3|, and subjected to selected further treatment, as already described. Fractionated vapors of the desired end-boiling point pass from the upper portion of fractionator 58 through line I82 and valve I83 to be subjected to condensation in con- 4 denser I84. The resulting distillate and gas passes from the condenser through line I85 and valve I86 to collection and separation in receiver IO'I. Uncondensable gas may be released from the receiver through line I88 and valve I88. Distillate may be withdrawn from the receiver through line I I8 and valve III to storage or further treatment, as desired.- A portion of the distillate collecting in receiver I81 may, when desired, be recirculated by well known means, not shown in the drawing, to the upper portion of fractionator 58 for the purpose of assisting cooling and fractionation in this zone, whereby to maintain the desired vapor outlet temperature and control the end-boiling point of the overhead product from the fractionator. In the same manner distillate from receiver 42 may be recirculated as cooling and refluxing medium to the upper portion of fractionator- 3|, by well known means not illustrated.

It will be understood that various other modifications may be made to the specific embodiment of the invention above described and that apparatus other than the specific form illustrated may be employed without departing from the scope of the-present invention. For example, instead of withdrawing both vaporous and liquid conversion products from chamber 85 in commingled state they may be separately withdrawn from this zone, the liquid passing either to mixing tank 6 or direct to heating coil I4 or being first subjected to further vaporization in a zone of reduced pressure, such as chamber 88 while the vaporous conversion products separately withdrawn from the reaction chamber may also be introduced, all or in part, into the vaporizing chamber at any desired point, when such a zone is employed, or they may pass, all or in part, direct to fractionator 58. For the sake of simplicity the connections required for such optional operations are not illustrated in the drawing, but those skilled in the art can make such connecticns quickly. It will also be understood that the optional methods of operation described are not to be considered equivalent but may be selected to suit specific requirements.

In an apparatus such as illustrated and above described, the range of suitable operating conditions may be approximately as follows: The conversion temperature employed at the outlet from the heating coil to which the combined feed is supplied may range, for example, from 800 to 930 and preferably a. substantial super-atmospheric pressure within the range of 100 to 500 pounds, or thereabouts, per square inch is employed at this point in the system. Substantially atmospheric, sub-atmospheric or a low superatmospheric pressure not in excess of 100 pounds, or thereabouts, per square inch is preferred in the coking ovens and the pressure employed in the coking zone may be substantially equalized in the succeeding fractionating, condensing and collecting equipment of this portion of the system. Coking temperatures employed may range from 950 to 1200 F., or thereabouts, and the coke produced may be further heated, when desired, to a temperature up to 1600 F., or more, for the purpose of devolatilizing the same. The second heating coil of the system to which intermediate condensates from the first described cracking and coking operations and all or a selected portion of the reflux condensate from the second cracking operation are supplied may utilize a conversion temperature, measured at the outlet therefrom, within the range of 900 to 1050 F.', or thereabouts, preferably with a substantial superatmospheric pressure, measured at this point, of from 200 to 800 pounds, or more, per square inch. Any desired pressure within substantially this same range may be employed in the reaction chamber but is preferably reduced in the vaporizing chamber to a pressure of from 100 pounds, or thereabouts, per square inch to substantially atmospheric. The pressure employed in the vaporizing chamber may be either substantially equalized or somewhat reduced in the succeeding fractionating, condensing and collecting portions of the system. i

As a specific example of the operation of the process of the present invention, the raw oil charging stock to be treated comprises a mixture of' about two parts by weight of pulverized coal of high volatility to one part of coal-tar. Heavy liquids from the separating and fractionating column of the coking system and residual liquid from the vaporizing chamber of the second cracking stage of the process are admixed with the charging stock in an amount approximately equivalent, by weight, to the coal-tar, so that the total combined feed supplied to the first cracking coil comprises about equal parts by weight of coal and oil. A conversion temperature of approximately 890 F., is employed at the outlet from the heating coil to which this material is supplied, a superatmospheric pressure of approximately 200 pounds per square inch being employed at this point in the system. The heated products are introduced into the coking ovens wherein the nonvaporous residue is reduced to coke at a temperature of approximately 1100 F. A slight subatmospheric pressure is employed in the coking zone and in the succeeding fractionating, condensing and collecting portions of the system. 60 Atemperature of approximately 300 F. is main- -.tained at the outlet from the fractionator of the (foking system so that a motor fuel product of slightly over 300 F., end-boiling point is recovered from this portion of the system. Interme- 65 diate condensates from the fractionator of the coking system, comprising materials boiling above the end-boiling point of the overhead product from the fractionator and up to aproximateiy 600 F., are supplied, together with reflux condensate from the fractionator of the second cracking stage of the process, to the heating coil of this portion of the system wherein the oil is subjected to an outlet temperature of approximately 935 F., at a superatmospheric pressure of approximately 75 400 pounds per squareinch. This pressure is substantially equalized in the reaction chamber and a reduced pressure of approximately 50 pounds per square inch is employed in the vaporizing chamber and succeeding fractionating, condensing and collecting equipment of this portion of the system.

An operation of the character above described may produce, per ton of charging stock, about 1320 pounds of coke of low volatility, about 40 gallons of motor fuel of high anti-knock valueand about 20% by weight of gas suitable for use as fuel.

I claim as my invention:

1. A process for the pyrolytic conversion and coking of a charging stock mixture of finely divided carbonaceous material in hydrocarbon oil which comprises subjecting the mixture to elevated temperature under non-coking conditions, introducing the heated products into a coking zone wherein the residue is coked in a relatively thin layer upon a highly heated surface, subjecting the vaporous products from the coking zone to fractionation whereby their fractions boiling above the range of the desired final light distillate product are condensed as intermediate liquid products, subjecting the fractionated vapors to condensation, returning high boiling components of said intermediate liquid products of the coking operation for further treatment with the charging stock mixture, simultaneously subjecting selected lower boiling components of said intermediate liquid products of the coking operation to conversion under independently controlled conditions, separating the resulting vaporous and residual liquid conversion products, returning the residual liquid for further treatment with the charging stock mixture, subjecting the vaporous conversion products to fractionation whereby their-insufliciently converted components are condensed as reflux condensate, subjecting fractionated vapors of the desired end-boiling point to condensation, and returning the reflux condensate for further treatment in the same system.

2. A process as defined in claim 1 further characterized in that said reflux condensate from the, cracking operation is returned for further conversion, together with said selected low-boiling fractions of the intermediate liquid products from the coking operation.

3. A process as defined in claim 1 further characterized in that said reflux condensate from the cracking operation is returned for further treatment with the charging stock mixture.

4. A process as defined in claim 1 further characterized in that selected low-boiling fractions of said reflux condensate from the cracking operation are returned for further conversion, together with said selected low-boiling fractions of the intermediate liquid products from the coking operation.

5. A process as defined in claim 1 further characterized in that selected low-boiling fractions of said reflux condensate from the cracking operation are returned for further conversion, together with said selected low-boiling fractions of the intermediate liquid products from the coking operation, higher boiling fractions of said reflux condensate being returned for further treatment with the charging stock mixture.

6. A process for the pyrolytic conversion and coking of mixtures of finely divided solid carbonaceous material in hydrocarbon oil which comprises subjecting said mixture to elevated temperature under non-coking conditions in a heating coil, introducing the heated products into a coking oven wherein the residue is coked in a relatively thin layer on a highly heated surface, introducing vaporous products from the coking oven into a, fractionator and tar separator wherein they are separated into low-boiling fractionated vapors which are subjected to condensation, intermediate condensate and higher boiling liquids, returning the latter to said coil for further treatment with the charging stock mixture, simultaneously subjecting said intermediate condensate to conversion under independently controlled conditions of elevated temperature and superatmospheric pressure in a separate heating coil and communicating reaction chamber, separating the resulting vaporous and residual liquid conversion products, returning the residual liquid for further treatment with the charging stock mixture, subjecting vaporous conversion products to fractionation whereby their insufliciently converted components are condensed as reflux condensate and separated into selected lowboiling and higher boiling fractions, and subjecting the fractionated vapors to condensation.

7. A process of the character defined in claim 6 wherein said low-boiling fractions of the reflux condensate from the cracking operation are returned to the last mentioned heating coil for further conversion.

8. A process of the character defined in claim 6 wherein said high-boiling fractions of the reflux condensate from the cracking operation are returned with the charging stock mixture for further treatment in the first mentioned heating coil.

9. A process ofthe character defined in claim 6 wherein said high-boiling fractions of the reflux condensate from the cracking operation are returned with the charging stock mixture for further treatment in the first mentioned heating coil and said low-boiling fractions of the reflux condensate from the cracking operation .are returned to the last mentioned heating coil for further conversion.

AIJFRED FISHER.

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