US1990254A - Hydrocarbon oil conversion - Google Patents

Description

Feb. 5, 1935. J. D. SEGUY HYDROCARBON OIL CONVERSION Filed April 2'7, 1931 JEAN DELATTRE SEGUY Patented Feb. 5, 1935 1 HYQROCARBON OIL CONVERSION Jean Delattre Seguy, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota Application April 27, 1931, Serial No. 533,103

8 Claims.

This invention relates to the treatment of hydrocarbon oils, and refers more particularly to the conversion of relatively heavy oils and the simultaneous'reconversion of various intermediate products from the primary conversion.

The primary features of the invention provide an improved process and apparatus for the conversion of oils comprising a primary cracking system for the conversion of raw oil charging stock and utilizing a heating zone, a reaction zone and a fractionating zone consisting of a primary and a secondary stage, a reduced pressure system for flash distillation of the residual oil from the primary cracking system comprising a flash distilling chamber and a fractionator and a secondary conversion system comprising a heating zone and a reaction zone in which flash condensate from the fractionator of the reisduum flash distilling system and reflux condensate from .the secondary fractionating stage of the primary conversion system may besubjected to reeonversion conditions.

Reflux condensate from the first fractionating stage of the primary conversion system is preferably returned to the heating element of this same system for reeonversion, but may be supplied in part to the stream of heated oil discharging from the heating element of the seeondary cracking system for the purpose of cooling the heated products to the desired temperature. Raw oil charging stock for the system may be introduced all or in part into the heating element of the primary cracking system or may be supplied all or in part to the stream of heated oil discharging from this same heating element being thereby, in the latter case, subjected to relatively mild conversion conditions at the same time cooling said stream of heated oil to a milder conversion temperature than that employed in the heating element.

The various features of the present invention will be more apparent with reference to the attaclied diagrammatic drawing, which illustrates one form of apparatus in which the process of the invention may be practiced.

Referring more in detail to the drawing, raw

- oil charging stock may be supplied through line 1 and valve 2 to pump 3, from which it may be fed through line 4 and valve 5 into heating element 6. The oil supplied'to heating element 6 which may be located within any suitable form of furnace '7 may be heated.to the desired conversion temperature under any desired pressure conditions and preferably under a substantial. superatmospheric pressure. The heated O l may be discharged through line 8, valve 9 and line 10 into reaction chamber 11. If desired, all or any portion of the raw oil charging stock may be diverted from line 4 and supplied through line 12 and valve 13 to line 10, commingling therein with 5 the stream of heated oil discharging from heat-- ing element 6, serving to cool these products to a milder conversion temperature than that employed in the heating element and. being itself thereby heated to a relatively mild conversion temperature.

Chamber 11 is also preferably maintained un-- der.a substantial superatmospheric pressure and vapors may be separated from the residual oil in this zone.

The vapors may pass. through line 14 and valve 15 to fractionator 16 which, as here illustrated, preferably comprises a primary fractionating stage designated as 17 i and a second-' ary fractionating stage designated in the drawing as 18. The relatively heavy insufliciently converted components of the vapors which may be condensed in zone 17 may pass through line 19 and valve 20 to pump 21 from which they may be fed all or in part through line 22, line 23 and valve 24 into line 4 and thence to heating element 6 for reeonversion.

The insufiiciently converted components of the fractionated vapors which may be condensed in zone 18 of the fractionator may collect upon tray or deck 25 to be supplied therefrom to further treatment as will. be more fully described later. This fractionation is preferably so controlled that the condensate thereof consists essentially ofpressure distillate bottoms. The relatively light desirable components of the fractionated vapors may pass through line 26 and valve 27, may be subjected to condensation and cooling in condenser 28, products from which may pass through line 29 and valve 30 to be collected in receiver 31. Uncondensable gas may be released from the receiver tnrough line 32 and valve 33 while distillate may be withdrawn through line 34 and valve 35.

Residual oil may be withdrawn from chamber 11 through line 36 and valve 37 to chamber 38 which is preferably maintained under a substantially reduced pressure relative to that employed in chamber 11 and wherein the residual oil may be further vaporized. Residual liquid remaining unvaporized in chamber 38 may be withdrawn therefrom to storage or elsewhere through line 39 and valve 40. Vapors evolved in chamber 38 may, if desired, pass all or in part through line 41 and valve 42 into fractionator 43.

Reflux condensate from the upper portion or zone 18 of fractionator 16 may be withdrawn through line 44 and valve 45 to pump 46. Likewise reflux condensate from fractionator 43 may be withdrawnthrough line 47 and valve 48, passing thence through line 44 to pump 46. If desired, a portion or all of the vapors from chamber 38 may be diverted from line 41, through line 49 and valve 50 into line 44 and thence to pump 46. The oils thus supplied to pump 46 may be fed through line 51 and valve 52 to heating element 53, which may be located within any suitable form of furnace 54 and wherein the oil may be heated to the desired, conversion temperature under any desired pressure conditions. Preferably, more severe conversion conditions are employed in heating element 53 than. those utilized in heating element 6 and these conditions may be within the range of either liquid-vapor-phase or vapor-phase cracking. The heated oil may be discharged from heating element 53 through line 55, valve 56 and line 57 into reaction chamber 58. If desired, a portion of the reflux condensate-from the lower portion of zone 17 of fractionator 16 maybe supplied from line 22, by means of pump' 21, through line 59 and valve 60 into line 57 commingling therein with the stream of heated oil discharged from heating element 53, serving to cool these products to a milder conversion temperature than that employed in heating element 53, being itself heated to a somewhat milder conversion temperature than that em-- ployed in heating element 53 by direct contact with said stream of heated products and passing therewith into chamber 58. Vapors may be separated from heavier products such as residual material and/or polymerization products in chamber 58. The heavy products may be withdrawn through 1ine'60 and valve 61, while the vapors may pass through line 62 and valve 63 to be subjected to fractionation in fractionator 43. It is thus evident that the recycle stock or reflux condensate resulting from fractionation of the vapors produced in the secondary system may be returned to the heating element of the same system for reconversion together with vapors from the residuum flash distilling operation, and if desired, together with the reflux condensate from the upper portion or zone 18 of fractionator 16. Instead of going to fractionator 43, vapors from chamber 58 may go to a separate fractionating zone (not shown) from which vapors are separately condensed and collected, and reflux condensate returned to line 51 for recracking in coil 53.

The relatively light desirable components of the vapors subjected to fractionation in fractionator- 43 may pass through line 64 and valve 85, may be subjected to condensation and cooling in condenser 66, products from which may pass through line 67 and valve 68 into receiver .69. Uncondensable gas may be released from receiver 69 through line 70 and valve 71. Distillate may be withdrawn from this receiver through line. 72 and valve 73. The usual expedience of assisting fractionation and controlling the outlet temperature oi.v the vapors from any K or all of the fractionating zones of'the system such as, fo example, supplying distillate from receiver 31 and/or from receiver 69 to fractionator 43 and/or fractionator 16, by well known means, may be employed although not here illustrated.

Pressures employed within the system may maybe utilized between any of the various elements. Preferably, a substantially reduced pressure relative to that employed in the primary cracking system is utilized in the residuum flash distilling system, while the secondary cracking system may utilize substantially the same, higher or lower pressure than that employed in the pri mary cracking system, depending upon the character of the distillate cracked therein as well as the results desired. Conversion temperatures employed may range from 800 to 1200 F., more or less. The pressures employed in the conversion zone are preferably of the order of to 1,000 pounds per square inch, and the preferred temperatures may range from 850 to 950 F. in this zone. The particular conditions employed will depend on the charging stocks as well as upon the results desired.

As a specific example of operating conditions of which, together with reflux condensate from the primary fractionating stage, is-subjected in the heating element of the primary cracking system to a conversion temperature of approximately 930 F. under a superatmospheric pressure of approximately 275 pounds per square inch. The temperature of the stream of heated oil from this heating element is reduced to ,approximately 900 F. prior to its introduction into the reaction chamber by supplying a portion of the raw oil charging stock directly into the stream of heated products. The reaction chamber of the primary cracking system is also maintained under a superatmospheric pressure of approximately 275 pounds per square inch but is reduced in the flash distilling chamber to approximately 30 pounds per square inch. Reflux condensate from the upper or secondary fractionating stage, reflux condensate from the fractionator of the sec ondary cracking system and substantially all of the gasoline-free vapors from the flash distillation of the residual oil are subjected to a temperature of approximately 1,000 FL, under a superatmospheric pressure of about 60 pounds per square inch in the heating element of the secondary cracking system. A sufficient quantity of reflux condensate from the lower or primary fractionating zone is introduced into the stream of heated oil from the heating element of the secondary cracking system to cool this material to a temperature of approximately 950 F. prior to its introduction into the reaction chamber of the secondary system.

' This operation may yield approximately 62% of motor fuel having an anti-knock value ap- I non-vaporous residue, the vapors subjected to fractionation to produce a light fraction, an in-, termediate fraction and a heavy fraction, the heavy fraction being returned to the heating zone for retreatment, and the non-vaporous residue being discharged into a reduced pressure zone where latent heat vaporization takes place, the improvement which'comprises admixing controlled amounts of the intermediate fraction from the fractionation with constituents vaporized in said reduced pressure zone of latent heat vaporization, subjecting said mixture to vapor phase cracking conditions, separating the lighter constituents of said vapor phase cracking from the heavier constituents, fractionating the lighter constituents and returning regulated quantities of the reflux condensate formed in said latter fractionation to the vapor phase cracking zone for retreatment.

2. A process such as claimed in claim 1 characterized in that regulated portions of the heavy fraction separated in the primary fractionation are diverted and admixed with the heated mass passing from the vapor phase cracking zone to the separating zone.

3. A process such as claimed in claim 1 characterized in that the vapors separated in the zone of reduced pressure are subjected to fractionation in the same zone as the vapors from the vapor phase cracking.

4. A process such as claimed in claim 1 wherein the conditions of fractionation are so controlled that the intermediate fraction consists essentially of pressure distillate bottoms.

5. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary cracking zone, separating the oil into vapors and unvaporized oil, subjecting the vapors to primary and secondary dephlegmation, returning resultant primary reflux condensate to the cracking zone for retreatment therein, flash distilling the unvaporized oil by pressure reduction and combining resultant flashed fractions with secondary reflux condensate formed by said secondary dephlegmation, supplying the mixture to a second cracking zone and cracking the same therein at higher temperature than is maintained on the oil in the primary cracking zone.

6. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary cracking zone, separatingthe oil into vapors and unvaporized oil, subjecting the vapors to primary and secondary dephlegmation, returning resultant primary reflux condensate to the cracking zone for retreatment therein, flash distilling the unvaporized oil by pressure reduction, dephlegmating the flashed vapors and combining resultant reflux condensate with secondary reflux condensate formed by said secondary dephlegmation, supplying the mixture to a second cracking zone and cracking the same therein at higher temperature than is maintained on the oil in the primary cracking zone.

7. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary cracking zone, separating the oil into vapors and unvaporized oil, subjecting the vapors to primary and secondary dephlegmation, returning resultant primary reflux condensate to the cracking zone for retreatment therein, flash distilling the unvaporized oil by pressure reduction, combining the flashed vapors with secondary reflux condensate formed by said secondary dephlegmation, supplying the resultant mixture to a second cracking zone and cracking the same therein at vapor phase cracking temperature.

8. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary cracking zone, separating the oil into vapors and unvaporized oil, subjecting the vapors to primary and secondary dephlegmation, returning resultant primary reflux condensate to the cracking zone for retreatment therein, flash distilling the unvaporized oil by pressure reduction, dephlegmating the flashed vapors and combining resultant reflux condensate with secondary reflux condensate formed by said secondary dephlegmation, supplying the mixture to a second cracking zone and cracking the same therein at higher temperature than is maintained on the oil in the primary cracking zone, and combining the cracked vapors from the second cracking zone with the flashed vapors undergoing dephlegmation whereby the heavier fractions of said cracked vapors are returned as reflux to the second cracking zone in said mixture.

JEAN DELATTRE SEGUY.

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