US2219521A - Conversion of hydrocarbon oils - Google Patents

Description

Oct. 29, 1940. J, B. HEID convsnsxon 0F mnnocmson OILS Original Filed May 24, 1935 FRACTIONATOR SEPARATING CHAMBER FURNACE 1 unvnpomzso ou REACTION CHAMBEE REFLUK UNVA POIZIZED 011:

INVENTOR JACOB BENJAMIN HEID ATTORNEY UNITED STATES PATENT OFFICE.

2,219,521 CONVERSION or HYDROCARBON OILS Jacob Ben Universal Oil Product jamin Heid, Chicago, Ill., assignor to s Company, Chicago, 111.,

a corporation of Delaware Application May newed M 3 Claims.

This invention refers to an improved process for the pyrolytic cracking of hydrocarbon oils for the production, primarily, desirable light distillate of high yields of such as motor fuel of good anti-knock value, wherein the charging stock is subjected to relatively mild cracking,

the intermediate liquid products of the process subjected to furthercracking within the same system under more severe conditions than those to which the charging stock is the residual liquid conversion subjected while products from both cracking stages are also subjected to further cracking and coking under independently controlled conditions within the same system.

In one embodiment the invention comprises subjecting hydrocarbon oil charging stock for the process to relatively mild cracking conditions of elevated temperature and superatmospheric pressure in a heating coil, separating t vaporous and liquid conversion pro to fractionation whereby their jecting the vapors insufficiently converted component he resulting ducts, sub- S are condensed as reflux condensate, subjecting fractionated vapors of the desired end-boiling point to condensation, recovering the resulting distillate, subjecting the reflux condensate to independently controlled conversion conditions of higher cracking temperature and superatmospheric pressure in a separate heating coil and communicating reaction chamber, withdrawing vaporous and liquid separately conversion products from said reaction chamber, commingling the vaporous conversion products from the reaction chamber with from the first mentioned the conversion products heating coil, prior to the fractionation of the vaporous components of the latter, subjecting the residual liquid Withdrawn from. the reaction chamber together with residual liquid from the first mentioned cracking stage to further cracking in a separate heating coil under non-coking conditions, resulting highly chamber wherein dry coke is products from the coking introducing the heated products into a coking their reduction to substantially accomplished, subjecting vaporous chamber to fractionation for the formation of reflux condensate, returning the reflux condensate for further conversion to the same heating coil to which the reflux condensate from the first mentioned cracking step is supplied,

subjecting fractionated vapors of the desired end-boiling point from the last mentioned fractionating stage to condensation and recovering the resulting distillate.

The accompanying diagrammatic lustrates one specific form of appara the invention may be carried out.

drawing iltus in which Referring to the drawing, hydrocarbon oil charging stock for the process, which may be a y desired type of oil but is normally an oil of relatively wide boiling range or of relatively highboiling characteristics, 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 heating coil 6. The charging stock may, of course, be preheated, when desired, in any well known manner not illustrated, prior to its introduction into the heating coil.

A furnace l of any desired form supplies the required heat to the oil passing through heating coil 6 to subject the same to the desired cracking temperature, preferably at a substantial superatmospheric pressure and the heated products are discharged from the heating coil through line 8 and valve 9 into separating chamber Ill.

Chamber I0 is preferably operated at a substantially reduced pressure relative to that employed in heating coil 6 in order to increase the degree of vaporization therein but may, when desired, be operated at substantially the same pressure as that employed at the outlet from the heating coil. Separation of vaporous and liquid conversion products is accomplished in chamber ID, the latter, being withdrawn from the lower portion of this zone through line H and valve I2 to pump I3 by means of which it is supplied through line 14 and valve 15 to heating coil 16 for further treatment, as will be later more fully described.

In the case here illustrated separating chamber l0 comprises the lower portion of column I1, the upper portion of which comprises fractionator I8, and the vaporous conversion products from chamber Ill pass through a suitable partition or deck 19 into the fractionator wherein their components boiling above the range of the desired light distillate product of this stage of the process are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling point are withdrawn, together with uncondensable gas produced by the operation, from the upper portion of fractionator l8 through'line 20 and may be directed through valve 2| in this line to condensation and cooling in condenser 22. The resulting distillate and gas passes through line 23 and valve 24 to collection and separation in receiver 25. Uncondensable gas may be released from the receiver through-line 26 and valve 2'1. Distillate may be withdrawn from receiver through line 28 and valve 29 to storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 25 may be recirculated by well known means, not shown in the drawing, to the upper portion of fractionator Hi to serve as a cooling and refluxing medium in this zone. It is also within the scope of the invention, when desired, instead of subjecting the fractionated vapors from fractionator Iii to condensation and collection, in the manner described, to divert the same from line 28 through line 30 and valve 3! into fractionator 59 wherein they may commingle with the other vaporous conversion products of the process and be subjected to fractionation therewith to be finally recovered, all or in part, together with the light distillate products of the process.

The reflux condensate formed in fractionator 58 may be withdrawn from the lower portion of this zone through line 33 and valve 34 to pump 35 by means of which it is supplied through line 36, valve 3'! and line 38 to heating coil 39 for further cracking.

Heating coil 39 is located within a furnace 49 of any suitable form by means of which the oil supplied to this zone is subjected to the desired cracking conditions of elevated temperature and superatmospheric pressure and the heated products are discharged from heating coil 39 through line M and valve 42 into a reaction chamber 43.

Chamber 43 is also preferably maintained at a substantial superatmospheric pressure and, although not indicated in the drawing, this zone is preferably insulated in order that cracking of the heated products supplied thereto and particularly their vaporous components may continue in the r action chamber. Separation of vaporousand liquid conversion products is accomplished in chamber 43 and the vaporous conversion products may be withdrawn in the case here illustrated from the lower portion of the chamber above the point of removal of the liquid conversion products, although they may be removed at any desired point or plurality of points in the reaction chamber, and are directed through line 44, valve 415 and line 8 into separating chamber Ill.

Liquid conversion products are withdrawn from the lower portion of chamber 43 through line 45 and valve 41 to pump 48 by means of which they are directed through line 49, valve 50 and line I4 to further treatment in heating coil I5 together with the liquid conversion products from chamber It, which are supplied to this zone as previously described.

Heating coil I6 is located within a furnace 5| and although the heating coil and furnace are illustrated in a conventional manner in the drawing they are preferably of such design (several forms of which are now well known in the art) that the relatively heavy oilssupplied thereto are quickly heated to the desired cracking temperature without allowingthe oil to remain in the heating coil and communicating lines for a sufficient length of time to permit any excessive formation and deposition of coke therein. This method of heating ormna'rily involves the use of relatively high oil velocities and relatively high rates of heating in the heating coil and in the preferred embodiment of the present invention the relatively heavy oils supplied to heating coil it are subjected therein to a temperature sufficient to effect their subsequent reduction to substantially dry coke in coking chamber 54, to which they are supplied from heating coil is through line 52 and valve 53.

Coking chamber 54 is preferably maintained at substantially atmospheric or a relatively low superatmospheric pressure, although higher pressures up to several hundred pounds per square inch may be employed in this zone, when desired. Coke produced in chamber 54 may be allowed to accumulate in this zone to be removed therefrom in any suitable well known manner, not illustrated, when the chamber has been substantially filled with coke or after its operation is completed for any other reason. It will be understood, of course, that although only one coking chamber is shown in the drawing two or more such zones may be employed, when desired, in which case they preferably are alternately operated, cleaned and prepared for further operation in order that the coking stage of the system may be operated continuously. Chamber 54 is provided with a suitable drain-line 55 controlled by valve 56 which may also serve as a means of introducing steam, water or any other suitable cooling medium into the chamber after its operation has been completed and preferably after it has been isolated from the rest of the system in order to hasten cooling and facilitate the removal of coke therefrom.

Vaporous products are withdrawn from the upper portion of chamber 54 through line 51 and valve 58 and are subjected to fractionation in fractionator 59 wherein their components boiling above the range of the desired final light distillate product of this stage of the process are condensed as reflux condensate. The reflux condensate is withdrawn from the lower portion of fractionator 59 through line 60 and valve 6| to pump 62, by means of which it is returned through line 63 and valve 64 to further cracking in heating coil 39, together with the reflux condensate from fractionator l8, which is supplied to this zone in the manner previously described.

Fractionated vapors of the desired end-boiling point are withdrawn from the upper portion of fractionator 59 through line 65 and valve 66 and are subjected to condensation and cooling in condenser 61. The resulting distillate and gas passes through line 68 and valve 60 to collection and separation in receiver 10. Uncondensable gas may be released from the receiver through line H and valve 72. Distillate may be withdrawn from receiver Til through line 13 and valve 14 to storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 10 may be recirculated by well known means, not shown in the drawing, to the upper portion of fractionator 59 to serve as a cooling and refluxing medium in this zone.

In a process such as illustrated and above described, the preferred operating conditions may be approximately as follows: The heating coil to which the charging stock is sup-plied may utilize an outlet cracking temperature ranging, for example from 800 to 950 F., or thereabouts, preferably with a superatmospheric pressure at this point in the system of from 160 to 500 pounds, or thereabouts, per square inch. The succeeding separating chamber is preferably operated at a substantially .reduced pressure relative to that employed in the heating coil although, when desired, this zone may be operated at a substantial superatmospheric pressure up to substantially the same as that employed in the heating coil. The fractionating, condensing and collecting equipment of this stage of the system may be operated at substantially the same or somewhat lower pressures than that employed in the separating chamber. The heating coil to which the reflux condensates from both fractionators of the system is supplied may utilize a cracking temperature, measured at the outlet therefrom, ranging,

for example, from 850 to 975 F., or thereabouts, preferably with a superatmospheric pressure at this point in the system of from 100 to 500 pounds or more per square inch. A substantial superatmospheric pressure substantially the same as that employed in the reflux heating coil or somewhat reduced relative thereto may be utilized in the succeeding reaction chamber. The heating coil to which residual liquid conversion products from the charging stock and reflux cracking stages of the system are supplied may employ an outlet cracking temperature'ranging, for example, from 900 to 1050 F., with a superatmospheric pressure which may range from slightly above atmospheric pressure to.300 pounds, or thereabouts, per square inchx The coking chamber may employ any desired pressure ranging from substantially the same as that in the preceding heating coil down to substantially atmospheric pressure and the pressure employed in the coking chamber may be substantially equalized or somewhat reduced in the succeeding fractionating, condensing and collecting equipment.

As a specific example of the operation of the process of the invention, the charging stock, which comprises a 30 A. P. I. gravity Mid-Continent topped crude, is subjected in the heating coil to which it is supplied to an outlet cracking temperature of approximately 900 F., at a superatmospheric pressure of about 300 pounds per square inch and the heated products are introduced into a separating chamber operated at a superatmospheric pressure of about 50 pounds per square inch. Liquid conversion products are withdrawn from the separating chamber and supplied to a separate heating coil. The vaporous conversion products from the separating chamber are subjected to fractionation for the formation of reflux condensate and the recovery of motor fuel fractions having an end-boiling point of approximately 300 F. The liquid conversion products from the separating chamber are quickly heated, together with liquid conversion products from the high-pressure reaction chamber of the system, in the separate heating coil to which these materials are supplied, to an outlet cracking temperature of approximately 970 F., at a superatmospheric pressure of about 75 pounds per square inch and the highly heated materials are introduced into a coking chamber maintained at substantially the same pressure, wherein they are reduced to coke. Vaporous products from the coking chamber are separately subjected to fractionation for the formation of reflux condensate and the recovery of motor fuel having an end-boiling point of approximately 400 F. The reflux condensates from both fractionators are supplied to a separate heating coil wherein this material is subjected toa cracking temperature, measured at the outlet therefrom, of approximately 940 F., at a superatmospheric pressure of about 350 pounds per square inch and the heated products are introduced into a reaction chamber maintained at substantially the same pressure. Residual liquid withdrawn from the reaction chamber is supplied, as previously mentioned, to the same heating coil as the residual liquid from the separating chamber of the first cracking stage and vaporous conversion products separately withdrawn from the reaction chamber are supplied to the separating chamber. This operation will produce, per barrel of charging stock, approximately 64 percent of motor fuel having an octane number of approximately 70 and approximately pounds of good quality low volatile coke, the remainder beingachargeable, principally to uncondensable gas. i

, I claim as my invention:

, :1'. A process for the 'pyrolytic conversion of hydrocarbon oils which comprises subjecting hydrocarbonroil charging stock for the process to py-rolytic conversion conditions of cracking temperature and superatmospheric pressure in the heating coil, introducing the resulting heated products into a reduced pressure separating chamber wherein separation of vaporous and liquid conversion products is accomplished, subjecting the vaporous conversion products to fractionation for-the formation of reflux condensate, recovering a desirable light distillate from the fractionated'vapors by condensation, subjecting the reflux condensate to independently controlled conversion conditions of perature and superatmospheric pressure in a heating coil and communicating reaction chamber, separating the vaporous and liquid converhigher cracking tem- 20 sion products in said reaction chamber, removing vaporous conversion products therefrom and 25 introducing the same into said reduced pressure separating chamber, separately removing the liquid conversion products from the reaction chamber, commingling the same with liquid conversion products WithdraWn from said reduced 30 pressure separating chamber and heating the commingled materials to a high conversion temperature under non-coking conditions in a separate heating coil, introducing the heated materials from said separate heating coil into a lowpressure coking chamber and reducing same therein to coke, subjecting vaporous products from the coking chamber to fractionation in a separate fractionating zone for the formation of reflux condensate, returning the reflux condensate from the last mentioned fractionating stage to further conversion in the same heating coil to which the reflux condensate from the first mentioned fractionating stage is supplied, subjecting fractionated vapors of the desired endboiling point from the said last mentioned fractionating stage to condensation and recovering the resulting distillate.

2. A process for the pyrolytic conversion of hydrocarbon oils which comprises subjecting hydrocarbon oil charging stock for the process to pyrolytic conversion conditions of cracking temperature and superatmospheric pressure in a heating coil, introducing the resulting heated products into a reduced pressure separating chamber wherein separation of vaporous and liquid conversion products is accomplished, subjecting the vaporous conversion products to fractionation for the formation of reflux condensate, recovering a desirable light distillate from the fractionated vapors by condensation, subjecting the reflux condensate to independently controlled conversion conditions of higher cracking temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, separating the vaporous and liquid conversion products in said reaction chamber, removing vaporous conversion products therefrom and introducing the same into said reduced pressure separating chamber, separately removing the liquid conversion products from the reaction chamber, commingling the same with liquid conversion products withdrawn from said reduced pressure separating chamber and. heating the commingled materials to a high conversion temperature under non-coking conditions in a separate heating coil, introducing the heated materials from said separate heating coil into a lowpressure coking chamber and reducing same therein to coke, subjecting vaporous products from the coking chamber to fractionation and returning resultant reflux condensate to the second-mentioned heating coil for further treatment therein together with the first-named reflux condensate.

3. A hydrocarbon oil conversion process which comprises heating topped crude oil to cracking temperature under pressure in a first heating coil and separating the same into vapors and unvaporized oil in a separating chamber, fractionating the vapors and subjecting resultant reflux condensate to independently controlled cracking conditions in a second heating coil,

introducing the heated reflux condensate into a second chamber maintained at cracking temperature and under higher pressure than the firstmentioned chamber, separating the resultant conversion products into vapors and residual liquid and combining the former with the firstmentioned vapors for fractionation therewith, commingling the residual liquid with unvaporized oil from the first-mentioned chamber and heating the mixture to coking temperature under pressure in a third heating coil, reducing the heated mixture to coke in a third chamber, fractionating vapors evolved in the third chamber independently of the first and second-mentioned vapors and supplying reflux condensate thus formed directly to said second coil, and finally condensing the fractionated vapors.

JACOB BENJAMIN HEID.

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