US1993894A - Art of cracking hydrocarbons - Google Patents

Description

March 12, 1935. PELZER ART 0F CRACKING HYDROQARBONS 2 Sheets-Sheet l Filed May 14, 1929 llllllll March 12, 1935,. H. 1 PELZER ART OF CRACKING HYDROCARBONS Filed May 14, 1923 2 Sheets-Sheet 2 ATTORNEYS Patented lMar. 12, 1935 PATENT O FFICE ART OF CRACKING HYDROCARBONS 4 Harry L. Pelzer, Highland, Ind., assignor to Sinclair Refining Company, New York, N. Y., a.

corporation of Maine Applicatipn May 14, 1929, serial No. 362,943

4 Claims.

This invention relates to improvements in the cracking of higher boiling hydrocarbon oils, such as crude petroleum, reduced crude oil, `fuel oil and gas oil, for the production of lower boiling hydrocarbon oils, such as gasoline, With the concurrent production ofa merchantable coke product.

In one aspect, this invention is an improvementin the. operations described in my application Serial No. 340,996, led February 18, 1929, Which has matured into Patent 1,831,719.

The improved operation of the present invention is a combined mixed phase high pressure cracking operation, vapor phase low pressure cracking operation and direct coking operation affordingseveral important advantages. The combined operation of the invention makes possible a reduction in the production of normally incondensable gases by subjecting the higher boiling components of the high boiling stocks subjected to the cracking operation to cracking conditions appropriate for the Ycracking of these components with a minimum production of such gases. The combined operation of the invention also make possible the use of` lower pressures in the high pressure mixed phase cracking operation by subjecting the lower boiling components of the high boiling stocks to a separate more .severe cracking operation in vapor phase. Thev `hot products discharged from such high pressure mixed phase cracking operations, as usually carried out, are usually at a ttemperature so high as to involve continuing decomposition with the formation of coke and yet not high enough to reduce the residual product of a dry merchantable coke. In the combined operation of this invention, the available heat of the hot products discharged from the low pressure vapor phase cracking operation is utilized inv a particularly advantageous manner to reduce to coke the residual product of the high pressure mixed phase cracking operation. By carrying out the combined operation of the invention to produce a coke product instead of a liquid residuum product, higher ultimate yields of gasoline are obtained so that an increased yield of the more valuable distillate product is obtained at the same time that the remaining residual product is reduced to a more merchantable form, that is cokeinstead of tar. According to the present invention, a stream of high boiling oil is heated to a high cracking temperature under low pressure and the hot products of this heating operation are introduced into a coking receptacle, a stream of higher boiling oil is heated to a lower cracking tem- (ci. 19e-4s) perature under higher pressure and the hot products of this heating operation are also discharged into the coking receptacle with reduction in pressure, the hot vapor mixture from the coking receptacle is discharged into and beneath the surface of a liquid body of oil in a scrubbing receptacle, oil from this liquid body in the scrubbing receptacle is supplied to the coking receptacle and there, together with unvaporized constituents of the hot products from the heating operations separated in the coking receptacle, is reduced to coke, the hot vapors from the scrubbing receptacle are discharged successively through a rst and a second fractionating operation, a high boiling fraction is condensed in a second fractionating operation and supplied to the iirst mentionedi low pressure heating operation, a higher boiling fraction is condensed in the rst fractionating operation and supplied to the second mentioned high pressure heating operation, and a gasoline fraction is .condensed from .the vapors discharged from theqsecond fractionating operation. A crude stock, crude oil or reduced crude oil, may be supplied directly to the coking receptacle orl better to the coking receptacle through the-scrubbing receptacle, or a gas oil stock or stocks may be supplied to the heating operations, or both such crude stocks and such gas oil stocks may be so supplied. Where the raw stock supplied to the combined operation of the invention consists exclusively of a crude stock, the high boiling and higher boiling stocks supplied to the lowpressure and the high pressure heating operations respectively are made up of components produced by the cracking operations to which are added components vaporized from the crude stock in the coking or the scrubbing operation Within the boiling ranges of the respective stocks. RaW gas oil stocks of appropriate boiling range may be supplied to the heating rated from crude stocks Within the combined operation of the invention, as a supplementary supply of raw oil, or the raw stock supplied to the operation may consist exclusively of one or more gas oil stocks. Where more than one .gas oily stock is supplied to the combined operation of the invention, lower boiling gas oil stocks are advantageously supplied to the low pressure heating operation and higher boiling gas oil stocks are advantageously suppliedto the high pressure heating operation. Crude stocks supplied to the combined operation of -the invention may be utilized, in whole 'or in part, as an indirect reiiuxing medium in either or both of the fracoperations with corresponding fractions sepainvention may be utilized, in whole or in part,

as a direct refluxing medium in either or bothof the fractionating operations or in the scrubbing operation.

The invention will be further described in connection with the accompanying drawings, in which Fig. 1 is a diagrammatic flow-sheet illustrating the invention and in which Fig. 2 illustrates, diagrammatically and conventionally, one form of apparatus adapted for carrying out the combined operation of the invention. It will be understood that other and diierent apparatus may be used. It will also be understood that the accompanying drawings are intended, primarily, to illustrate the relation of operations in processes embodying the invention; for example, in practice, coking receptacles such as the four illustrated are usually arranged as a compact group making the connections between them much shorter than these connections appear in the drawings and the two heaters illustrated are, in practice, usually arranged close to the coking receptacles to which they are connected.

The two fire-heated heaters illustrated, E and F, each 'comprises a group of series connected heating tubes 1 (the rference letter e or f is appended on the drawings to identify each element with the heaters lE and F respectively) arranged in a heating ue 2, a fan 3 for circulating the heating gases from the rebox 4 through the heating flue 2, and ducts 5, 6, 7 and 8 provided with dampers (as shown) for recirculating part of the heating gases through the heating nue 2 and for discharging part of' the heating gases' to a stack (not shown) through an air preheater (not shown) for supplying preheated air for combustion through duct 9 to the iirebox 4.

In carrying out the invention in the apparatus illustrated, the low pressure cracking operation is carried out in heater E and the high pressure cracking operation in heater F, valve 76 being provided for maintaining and regulating pressure in the heater F.

The coking receptacles illustrated, A, B, C and D, may be arranged and operated as described in my application Serial No. 341,214, filed February 19, 1929, which has matured into Patent 1,873,024, for example. Each of these four coking receptacles is provided with a connection 12 (the reference letter a, b, c or d is appended on the drawings to identify each element with the receptacles A, B, C and D respectively) for introducing the hot products from the heater E into the receptacle, with a connection 13 for introducing the hot products from the heater F into the receptacle, with a connection 14, for introducing oil supplied from the scrubbing receptacle 10 into the receptacle, and with a connection 16 for discharging the hot vapor mixture from the coking receptacle to the scrubbing receptacle 10. Valves 17, 18 and 19 and valves 23, 24 and 26 are provided to permit, for example, the discharge of the hot products from heater E through connection 27 and the discharge of the hot products from heater F through connection 28, respectively, into the coking receptacles A, B, C, D, A, etc. in succession; and valves 29, 33 and 34 are provided to permit, for example, the discharge of the hot vapor mixture from the coking receptacles A, B, C, D, A, etc. in `succession into the scrubbing tower 10 through connection 36. Valves 17, 18, 23, 24,

29 and 33 are shown as positioned while carrying v ward W. Isom and George H. Taber, Jr.

out a coking operation in receptacle A, receptacle B then being charged for the next coking operation, receptacle C then being steamed out and receptacle D then being cleaned after discharge of the coke product of the preceding coking operation, as described in application Serial No. 341,214

mentioned above. Valves 17, 18, 19,23, 24, 26, 29, 33 and 34 may, with advantage, be of the type described in application Serial No. 342,904 filed February 26, 1929, by Eugene C. Herthel and Willis S. Gullette. The connection 12 may be arranged to discharge into the lower part of the coking receptacle, or as described in application Serial No. 347,533 filed March 16, 1929, by Ed- The connections 13 and 14 may be arranged to discharge into the upper part of the coking receptacle and, with advantage, to discharge into the coking receptacle above the charge of coke accumulating therein during operation.

The scrubbing receptacle illustrated, 10, may, with advantage, be constructed and operated as described in application Serial No'. 345,199 led March 7, 1929, byEugene C. Herthel, which has matured into Patent 1,810,048. The scrubbing tower 10 comprises a lower, an intermediate and an upper part. The lower part is adapted for maintaining a liquid body of oil during operation normally submerging the inlet connection 37 through which connection 36, from the coking receptacles, discharges. The intermediate part is provided with open balles 38 and the upper part is provided with bubble plates 39. Connections 41 and 42 are provided for the introduction of a refluxing Amedium into the upper part of the tower. Reflux condenser 11 is also provided for supplying a refluxing medium to the upper part of the tower. Vapors escape from the upper part of tower 10 through connection 43 to the lower part of tower 20.

The fractionating towers illustrated, 20 and 30, may be of conventional bubble tower construction. Connections 44 and 45 are provided for supplying raw stock to the upper part of these towers, respectively, and connections 49 and 51 are provided for supplying raw stock to the lower part of these towers, respectively. Raw gas oil stocks may be supplied by means of either or both of pumps 47 and 86 through the headers to which these pumps are connected. If different gas oil stocks are so supplied to the operation, lower boiling gas oil stocks may be supplied by means of pump 86 and higher boiling gas oil stools by means of pump 47. By means of the valved connections provided (as shown), gas oil stocks supplied by either of the pumps 47 or 86 may be introduced, either in whole or in part, either into the upper end or into the lower end of either of the fractionating towers 20 and 30 through connections 44, 45, 49 and 51, or into the upper end of the scrubbing tower 10 through connection 41, or supplied to the heaterE through connections and 73 or supplied to the heater Fthrough connections 91 and 67. The operation of the towers 20 and 30 may be controlled by means of either or both of the reflux condensers 21 and 22, or either or both of the reux condensers 31 and 32, respectively, alone or in conjunction with the introduction of a refluxing medium through connections 44 and` 45. An extraneous cooling medium, water for example, may bev circulated through the heat exchanging coils in either or both of the reflux condensers 22 and 32. Vapors escapev the upper part of tower 30 through connection 48.

'Ihe reflning tower 40, in conjunction with the fractionating tower 50, may with advantage be arranged and operated as described in applica- 5 tion Serial No. 257,958 filed February 29, 1928, by

Eugene C. Herthel, which has matured into Patent 1,781,388. The rening tower 40 'is arranged to subject a vapor mixture passing therethrough to the action of an adsorptive catalyst such as fullers earth and the fractionating tower 50 is arranged to separate from the composite product discharged from the refining tower through connection 53 the polymers and other high boiling components produced by the vapor-catalyst contact, and lany other constituents higher boiling than suitable as components of the desired. product. The operation of the fractionating tower 50 may be controlled by the regulated introduction of a refluxing medium through connection 54 by means of pump 56; a part of the product supplied through connection 57 or some similar fraction supplied ,through connection 58, for example. The higher boiling components separated in the tower 50 maybe introduced, in whole or in part,

g5 -into the tower 10 through connections 62 and 4.2

by means of pump 55 or discharged through connections 62 and 63. product, gasoline for example, escape from the upper part of tower 50 through connection 59 to condenser 60 arranged to discharge into receiver 70 from which the distillate product is discharged through connection 71 and uncondensed vapors and gases through connection 72. Instead of being discharged through the rening tower 40, the vapor mixture escaping through connection 48 may, for example, be discharged through connection 61 to a condenser similar to condenser 60 connected-to a receiver similar to receiver 70.

The high boiling condensate separated in fractionating tower 30 is supplied to heater E through connections 68 and 73 by means of hot oil pump 35. The higher boiling condensate separated in fractionating tower 20 is supplied to heater F rthrough connections 64 and 67 by means of hot oil pump 25. Additional stocks may be supplied to the heaters E and F through connections 90 and 91, respectively, as described above. The residual stock mixture formed in the scrubbing tower lO is supplied to the coking receptacles A, B, C and D through connection 74 and manifold 87 by means of hot oil pump 15. Crude stocks` may be supplied by means of pump 89 through connection 77, passed, either in whole or in part, through any one or more of the heat exchanging coils in any'or all of the reux condensers l1, 21 or 31, by means of the valved branch connections provided (as shown) and introduced either into the liquid body of oil in the lower part of tower 10 through connection or supplied to the coking receptacles 80 with the residual oilfrom the tower 10 through connection 74 and manifold 87 by means -of connection 66.

The particular type of hot oil pump illustrated, designated 15, 25, 35 and 55, is described in more 65 detail in Letters Patent No. 1,701,199 issued February 5, 1929, on the application of Thomas YdeColon Tifit.

The combined operation ofthe invention will be further illustrated by the following examples of processes embodying the invention as carried out in the apparatusillustrated in the accompanying drawings :i

First example-Reduced crudeis supplied to the coking receptacle A, for example, or one of 75 the other coking receptacles of the group, by

The vapors forming the means of pump 89, the heaters E and F being in operation. In the coking receptacle the oil components of the reduced crude are vaporized and a higher boiling gas oil including the appropriate constituents of these vaporized components is separated in tower 20 and a lower boiling gas. oil including the appropriate constituents of these vaporized components is separated in tower 30. The gas oil condensate separated in tower 30 is supplied to the heater E in which it is heated to a temperaturein the neighborhood of 1100-1150 F. under presssure just sucient to maintain flow through the apparatus. The gas oil condensate separated in tower 20 is supplied to the heater F in which it is heated to a temperature in the neighborhood of SOO-950 F. under a pressure in the neighborhood of 20D-400 pounds per square inch. This pressure is maintained and regulated by means of valve 76. The hot products from both heaters E and F are discharged into the coking receptacle A, or one of the other coking receptacles of the group, the pressure on the hot products from the heater F being reduced to that prevailing in the coking receptacle as they pass the valve'76. The hot vapors discharged from the coking receptacle A, or one of the other coking receptacles of the group, are discharged into and beneath a liquid body of oil maintained in the lower part of the scrubbing tower 10. The resulting oil mixture is-supplied from the liquid body in the scrubbing tower 10, together with the reduced crude iirst mentioned, to the coking receptacle A, or one of the other coking receptacles of the group. In the coking receptacle,

the oil components of the oil mixture so supplied are vaporized and the residual components are reduced to coke by the heat of the hot products discharged from the heaters E and F. llhe production of a dry coke product is promoted by discharging the higher temperature hot products from the heater E into the coking'receptacle at a lower point than the lower temperature ho-t products from the heater F. The liquid-body in the lower part of tower l0 is maintained at a temperature approximating S75-775 F. The vapors escaping from the tower 10, including vapors discharged from the heaters E 'and F aswell as vaporized components of oil supplied to the coking receptacle rst mentioned, escape to the frac-- tionating towers 20 and 30 where the stocks supplied to the heaters E and F, respectively, are separated, and a gasoline or gasoline containing product is condensed from the remaining vapors escaping from the fractionating tower 30.

Second example-In the foregoing example, the operation of the fractionating towers 20 and 30 may be controlled by. regulated circulation of the raw crude stock through the reflux condensers 2l and 3l and/or the regulated circulation of an extraneous cooling medium through the redux condensers 22 and 32. Instead of so regulating the operation of towers 20 and 3u, this operation may be controlled or such control supplemented by the regulated introduction of one or more vraw gas oil stocks into the upper ends of towers 20 and 30 through connections 44 and 45, a higher boiling gas oil stock through connection 44 and a lower boiling gas oil stock through connection 45, for example. f

Third creampie-Raw gas oil stocks of corresponding character may be supplied to the condensate stocks separated in the towers 20 and 30, respectively, through connections 49 land Fourth. example.-Instead of supplying a -raw under low pressure crude stock toy the coking receptacles, as in the operation of the iirst example, raw gas oil stocks fre supplied to the heaters E and F through connections 49 and 51 or through connections and 91 by means of pumps 4'7 and 86. A single The oil supplied from the liquid body in the scrubbing receptacle to the coking receptacle, in

carrying out the combined operation of the present invention, may be preheated in a separate fire-heated heater before introduction into the coking receptacle as described in my application Serial No.355,780 le'd April 1'7, 1929, which has matured 'into Patent 1,937,163.

I claim:

1. In the manufacture of gasoline, the improvement which comprises heating a stream of high boiling oil to a high cracking temperature products of this heating operation into a coking receptacle, heating astream of higher boiling oil to a lower cracking temperature under higher pressure and introducing the hot products of this heating .operation into said coking receptacle with reduction in pressure, discharging the hot vapor mixture from the coking receptacle. into and beneath the surface of a liquid body of oil in a scrubbing receptacle, supplying oil from this liquid body in said scrubbing receptacle to said coking receptacle and reducing the oil so supplied thereto together with unvaporized constituents of the hot products from the heating operations separated therein to coke in said coking receptacle, discharging the hot vapors from said scrubbing receptacle successively through a rst and a second fractionating operation, condensing a high boiling fraction in Y the second fractionating operation and supplying the condensed fraction to the first-mentioned heating operation, condensing a higher boiling fraction in the first fractionating operation and supplying the condensed fraction to the second-mentioned heating operation, and condensing a gasoline fraction from the vapors discharged from the second fractionating operation. f

2. In the manufacture of gasoline, the improvement which comprises heating a stream of high boiling oil to a high cracking temperature under low pressure and introducing the hot products of this heating operation into a coking receptacle, heating a stream of higher boiling oil to a lower cracking temperature under higher pressure and introducing the hot products of this heating operation into said coking receptacle with reduction in pressure, discharging the hot vapor mixture from the coking receptacle into and beneath the surface of a liquid body of oil in a scrubbing receptacle, supplying a crude stock to said coking receptacle together with oil from the liquid body in said scrubbing receptacle and reducing the oil so supplied to said coking receptacle together with unvapo-rized constituents of the hot products from the heating operations separated therein to coke in said coking receptacle, discharging the hot vapors from said scrubbing receptacle successively through a first and a second fractionatlng operation, condensand. introducing `the hot' ing a high boiling fraction in the second. frac-I tionating operation and supplying the condensed fraction to the first-mentioned heating operation, condensing a higher boiling fraction in the rst fractionating operation and supplying the condensed fraction to the second-mentioned heating operation, and condensing a gasoline fraction from the vapors discharged from the second fractionating operation.

3. In the manufacture of gasoline, the improvernent which comprises heating a stream of high boiling oil to a high cracking temperature under low pressure and introducing the hot p roducts of this heating operation into a coking receptacle, heating a stream of higher boiling' oil to a lower cracking temperature under higher pressure and introducing the hot products of this heating operation into said coking receptacle with reduction in pressure, discharging the hot vapor mixture from the coking receptacle into and beneath the surface of a 'liquid body of oil in a scrubbing receptacle, supplying a crude stock to said scrubbing receptacle, supplying oil from the liquid body in said scrubbing receptacle including the constituents of such crude stock unvaporized therein to said coking receptacle and reducing the oil so supplied thereto together with unvaporized constituents of the hotproducts from the heating operations separated therein to coke in said coking receptacle, discharging the hot vapors from said scrubbing receptacle successively through a first and a second fractionating operation, condensing a high boiling fraction in the second fractionating operation and supplying the condensed fraction to the rst-mentioned heating operation, condensing a higher boiling fraction in the first fractionating operation and supplying the condensed fraction to the second-mentioned heatlng operation, and condensing a gasoline fraction from the vapors discharged from the second fractionating operation.

4. In the manufacture of gasoline, the improvement which comprises heating a stream of high boiling oil to a high cracking temperature under low pressure and introducing the hot products of this heating operation into a coking receptacle, heating a stream of higher boiling oil to a lower cracking temperature under higher pressure and introducing the hoi'l products of this heating operation into said coking receptacle with reduction in pressure, discharging'the hot vapor mixture from the coking receptacle into and beneath the surface of a liquid body of oil in a scrubbing receptacle, supplying oil from this liquid body in said scrubbing receptacle to said coking receptacle and reducing the oil so supplied thereto together with unvaporized constituents of the hot products from the heating operations separated therein to coke in said `coking receptacle, discharging the hot vapors from said scrubbing receptacle successively through a first and a second fractionating operation, condensing a high boiling fraction in the second fractionating operation and supplying the condensed fraction to the iirst-mentioned heating operation, condensing a higher boiling fraction in the first fractionating operation and supplying the condensed fraction to the second-mentioned heating operation, supplying a raw gas oil stock to one of the heating operations, and condensing a gasoline fraction from the vapors discharged from the second fractionating operation.

HARRY L. PELZER.

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