US1836181A

US1836181A - Distillation and cracking of oil

Info

Publication number: US1836181A
Application number: US371865A
Authority: US
Inventors: Mendius William
Original assignee: Sinclair Refining Co
Current assignee: Sinclair Refining Co
Priority date: 1929-06-18
Filing date: 1929-06-18
Publication date: 1931-12-15
Anticipated expiration: 1948-12-15

Description

Dec. 15, 1931. w. MENDlUs y DISTILLATION AND CRACKING 0F OIL Filed June 18, 1929 LAUMUUN Mv Z .You

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` Patented Dec. 15, 1931 UNITED STATES PATENT oI-FICEv `WILLIAM MENDIUS, OF CHICAGO, ILLINOIS, ASSIGNOR T SINCLAIR REFINING COM- PANY, 0F NEW YORK, N. Y., A CORPORATION 0F MAINE DIST'ILLATION-AND CRACKING- 0F OIL Appuation mea :une 1s,

This invention relates to improvements 1n the manufacture of lower boihng oils such as gasoline from higher boiling oils-suchA as gas oil, crude petroleums and reduced crude petroleums by cracking, to improvements in the. manufacture of lubricating oils from crude petroleums and reduced crude petroleums by vacuum distillation, and to improvements in reducing to coke residual components of such crude stocks; more particularly the invention relates to a combined operation having several important advantages in the manufacture of lower boiling oils such as gasoline and inthe manufacture of lubricating oils and' in reducing residual stocks to coke.

According to the present invention, a residual stock is reduced to coke by direct introduction into the oil to be coked of hot oil products from a vapor phase cracking operation, a crude stock containing lubricating oil components is preheated by indirect heat exchange with hot oil products escaping from the coking operation and lubricating oil stock is vaporized from the thus preheated crude stock under sub-atmospheric pressure, and

residual stock from the vaporizing operation, in which the lubricating oil stock is separated from the preheated crude stock, is supplied to the coking operation. A gas oil stock is condensed from the hot oil products escaping from the coking operation and this condensed gas oil stock is supplied to the vapor phase cracking operation. The residual stock supplied'to the coking operation may include tar components separated from A the. hot oil product escaping lfrom the coking operation as Well as the residual stock from the vaporizing operation in which the lubricating oil stock is separated from the preheated crude stock.

A number of advantages are thus secured. This combined operation makes use ofheat available in the hotoil products from the vapor phase cracking operationto separate lubricating oil components from crude stocks in a particularly advantageous manner. In this combined operation, decomposition of lubricating oil components of the crude stock, as through local overheating, is reduced to a 1929. Serial N0. 371,865.

minimum although residual components of the crude stock are reduced to coke in the same operation. In this combined operation, lubricating oil stocks separated from the crude stock are not subjected to contamination or deterioration through contact with lower boiling or reactive components of the hot oil products discharged from the vapor phase cracking operation. In this combined operation, gas oil stocks or stock components produced by coking of the residual stock from the vaporizing operation are supplied directly to the vapor phase cracking operation. 'The combined operation of the invention frequently makes possible an increased recovery oflubricating oil stocks from the same crude stock Without prejudice to the economy of the complete operation.v Although severtl sub-operations are involved in this combined operation, the apparatus required for carrying out the operation may be made quite simple.

The preheating of the crude stock supplied to the vaporizing operation may b e effected, in

.carrying out the invention, in a number of Ways. This crude stock may be preheated, for example, by indirect heat exchange with vapors or liquids in a'scrubbing operation for the separation of tar components to which the hot oil products escaping from the coking operation are subjected, by indirect heat exchange With the vapors escaping from such a scrubbing operation, by indirect heat exchange with vapors or liquids in or escaping from fractionating or condensing operations to which vapors escaping from such a scrubbingv operation, or from the coking operation, are subjected, or by any combination of such several Ways.

The invention will be further described in connection With the accompanying drawing which illustrates, diagrammatically and conventionally, one form of apparatus adapted for carrying out the invention. It Will be understood that other and different apparatus may be used.

In carrying out the combined voperation of the invention in the apparatus illustrated, the vapor phase cracking `operation is carried out in the heater l, the preheating of the crude stock containing a lubricating oil component is carried out in either the heat exchanger 2 or the cooling coils of reiux condenser 3 or reflux condenser 4 or the heat exchange coil 5 (arranged in the scrubbing tower 10) or in a combination of these heat exchange means, the vaporizing operation for separation of lubricating oil components from the preheated crude stock is carrled out in tower 6, operated under sub-atmospheric pressure, and the coking operation is carried out in one or more of the coking receptacles 7, 8, etc.

The vapor phase cracking operation proper may be carried out, for example, as described in application Serial No. 198,621 filed June 13, 1927, by Harry L. Pelzer, and the hot vapor mixture from the digesting drums discharged directly into the coking receptacles, or the digesting drums may be omitted and the hot'vapor mixture from the heater proper discharged directly into the coking receptacles, as in the apparatus illustrated. In this apparatus, the vapor phase cracking operation proper is carried out in the heater 1 comprising a group of series connected heating tubes arranged in the heating flue of a furnace 30, a fan 31 being provided for circulating the heating gases through the heating fine, ducts 32 with dampers as shown being provided for recirculating part of the heating gases through the heating ilue and for discharging part of the heating gases to stack 33, and fan 34 and preheater 35 arranged in the stack 33 being provided for supplying preheated air for combustion to the lirebox 36 of the furnace 30. Oil is supplied to the heater 1 through c'onnecton 37 and the hot oil products of the vapor phase cracking operation carried out therein are discharged through connection 38 to the coking receptacles.

A series of coking receptacles 7, 8, etc., is provided so that a coking operation, such as is described in application Serial No. 340,996, filed February 18, 1929, by Harry L. Pelzer, may be carried out continuously therein, one or more of the series being in use for carrying out the coking operation proper while others are shut down for discharge of the coke product or for cleaning or repair. But two coking receptacles are shown to simplify the drawings. Such a series of coking receptacles may be operated, for example, as described in application Serial No. 341,213, filed February 19, 1929, by Harry L. Pelzer. One form of valve specially adapted for making the change-over from one coking receptacle to another coking receptacle during operation is described in application Serial No. 342,904, filed February 26, 1929, by Eugene C. Herthel and Willis S. Gullette. The hot oil products from the vapor phase cracking operation are introduced into the coking receptacle 7 for example, through connection 9. This connection 9 may be arran ed to discharge into the lower part of the co ing receptacle or as described in application Serial No. 347,533, filed March 16, 1929, by Edward W. Isom and George H. Taber, Jr. Residual stock to be coked is su )plied to the coking receptacle 7, for examp e, through connection 1l or through connections 11 and 12. Vapors escape from the coking receptacle 7 for example, through connections 13 and 15.

The scrubbing tower 10 may, with advantage, be arranged and operated as described in application Serial No. 345,199 filed March 7, 1929, by Eugene C. Herthel. This 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 14 through which connection 15 from the coking receptacles discharges. The intermediate part is provided with open baflies 16 and the upper part is provided with bubble plates 17. Residual stock is supplied from the liquid body in the lower part of tower 10 to the coking receptacles through connection 57 by means of pump 58, to receptacle 7, for example, through connection 12. The operation of this tower is controlled by direct introduction of a refluxing medium or by means or" reflux condenser 4 or by both of these means. Connection 18 is provided Jfor the introduction of a refluxing medium into the upper part of the tower. Reflux condenser 4 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 19 to the lower part of tower 20. The heat exchange coil 5 (previously mentioned) is arranged in the intermediate part of the tower 10.

The fractionating tower 20 may be of conventional bubble tower construction. This tower may be operated, for example, as described in application Serial No. 345,199, filed March 7, 1929, mentioned above. Connection 21 is provided Nfor supplying raw stock to the lower part of this tower. The operation of this tower may be controlled by means of either or both of the reflux condensers 3 and 23 or by the direct introduction of a reluxing medium through connection 22 or by both of these means. In the apparatus illustrated these reflux condensers are shown as arranged for the use of crude stocks supplied to the operation and gas oil stocks supplied to the operation, respectively, as cooling media. An extraneous cooling medium, such as water, may, however, be used in either of these reflux condensers. A direct reiuxing medium, such as a part of the cracked distillate product or a similar fraction, may be supplied to the upper part of tower 20 through connection 22 by means of pump 2A.

The vapors formin the cracked distillate product escape from t e upper part of tower 20 through connection 25 to condenser 26` This condenser is arranged to discharge into the receiver and gas separator 27 from which the condensed cracked distillate product is discharged through connection 28, uncondensed vapors and gases being discharged through connection 29.

The vaporization operation for the separation of lubricating oil components from the crude stock supplied to the operation is carried out in vacuum tower 6. Crude stock is supplied to the operation through connection 39 by means of pump 40. This stock is preheated to a temperature at which the lubricating oil components are vaporized under the pressure prevailing in the tower 6 by circulation through one or more of the several heat exchange means previously mentioned, the heat exchanger 2', the heat exchange coils in the reflux condensers 3 and 4 and the heat exchange coil 5 in the scrubbing tower l0,

. the heat exchange in every case being indirect.

The preheated crude stock is released into the lower part of tower 6 through connection 41 including valve 42. In this tower lubricating oil components of the crude stock are separated by vaporization from the remaining residual stock. The residual stock is supplied through connection 43 by means of pump 44 to the coking receptacles, to the coking receptacle 7 through connection 11 for example. rllhe vaporized lubricating oil components, or the lower boiling of these components, escape from the upper part of tower 6 through connection45 to condenser 46. A hi her boiling lubricating oil fraction, a distllled bright stock, for example, may be condensed in the upper part of the tower 6 and discharged through connection 47 and cooler 48. The operation of this tower may be controlled by regulation ,of the sub-atmospheric pressure maintained therein, or by circulation of an extraneous cooling medium or of gas oil, or part of it, supplied to the combined operation through the heat exchange coil in the reflux condenser 59. Condenser 46 is arranged to discharge into receiver 49 and cooler 48 into receiver 50 from which receivers the lubricating oil fractions are pumped by means of pump 51 and pump 52, respectively. The required sub-atmospheric pressure is maintained in the vacuum tower 6 by means of an exhauster 53 connected to the

receivers

49 and 50 through connections 54 and 55, respectively.

The condensate or condensate mixture collecting in the lower part of tower 2O is supplied, by means of pump 56 through heat exchanger 2 and connection 37, to the vapor phase cracking operation. This stockusug ally of gas oil character, may consist exclu;

sively of components vaporized from the residual stock supplied to the coking receptacles from the lower part of the tower 6, or from this residual stock and the residual stock supplied to the coking receptacles from the liquid body maintained in the lower part of scrubbing tower V10. Or this stock may include, in addition to such components, additional gas oil components from gas oil supplied through connection 60 by means of pump 61, to the lower part of tower 20 through connection 21, or to the upper part of tower 10 through connection 18, vaporized therein and condensed in tower 20. Gas oil so supplied to the operation may be used, in whole or in part, as a cooling medium either in the reflux condenser 59 for controlling the operation of the tower 6 or in the vheat exchange coil 5. If additional heat is required, this crude stock, or part of it, may be circulated through the heat exchange coil in the reflux condenser 3. lf such heat exchange is insufficient to maintain control of the scrubbing operation carried out in tower l0 or ofthe fractionating operation carried out in tower 20, another stock cooling medium or an extraneous cooling medium is used or a direct refluxing medium is supplied to the operations. It will be understood that the requirements of diierent operations, the maintenance of different stockA balances, for example, may require variation of the precise heat exchange scheme usedto combine the necessary preheating of the crude stock supplied to the vacuum tower 6 with the required control of the scrubbing tower 10 and the fractionating tower 20. p The invention will be further illustratedY by the following more detailed example oi" one operation embodyingu the invention as carried out in the apparatus illustrated:

Reduced crude,supplied by means of pump 40, is circulated successively through the heat exchanger `2 and the heat exchange coil in the refluxcondenser 4-and thereby preheated to a temperature of about 650 F. and, at this temperature, the preheated reduced crude is released within the lower part .of the vacuum tower 6, the latter being maintainedV under a pressure of about30 mm. of mercury absolute. ln the vacuum tower 6, the larger part of the reduced crude, say 75%, is vaporizedv leaving a residual stock, 10 API for examf; ple, which is supplied to the coking receptacles by means of pump 44. The vaporized part of the preheated reduced crude is collected as a lubricating o il fraction or fractions in the receiver 49 or in the

receivers

49 and 50. Gas oil character stock is supplied from the lower part of tower 20 by means of pump 56 through the heat exchanger 2 t0 the vapor phase cracking operation carried out in heater l. Here this gas oil stock is heated, for example, to a temperature in the neighborhood or HOO-11500 F. under pressure just suicient to maintain iow through the coking receptacles, the scrubbing tower 10, the fractionating tower 20 and the condenser 26 to receiver 27, the latter being maintaind under atmospheric pressure or some pressure slightly above atmospheric pressure. In the cokingl receptacles, 4the residual stock supplied from the vacuum tower 6, together with the residual stock supplied from the lower part of tower l0, is reduced to coke by direct heat exchange with the hot oil products discharged from the vapor phase cracking operation. The hot vapor mixture from' the coking operation is discharged into and beneath the surface of a liquid body of oil maintained in the lower part of tower 10 and there stripped of tar components, the latter being returned to the coking operation with residual stock from this liquid body, this liquid body being maintained, for example, at a temperature in the neighborhood of 725-775 F. In the fractionating tower 20, the gas oil 4components of the vapor mixture escaping from tower l0 are condensed to be supplied to the heater l together with sufficient additional raw gas oil, supplied through connection 60, to maintain the required supply of oil for the vapor phase cracking operation. This fractionating operation may be controlled, for example, to effect the condensation of all components of the entering vapors higher boiling than suitable as components of the desired distillate product, gasoline for example. The products of the combined operation may thus comprise a gasoline or a gasoline fraction, a lubricating oil fraction or fractions and a coke product.

I `claim:

1. In an operation combining the separation of lubricating oil components from crude stocks containing the same and the production of a cracked distillate product, the improvement which comprises reducin residual stock to coke by direct introduction into the oil to be coked of hot oil products direct from a vapor phase cracking operation, heating a crude stock containing lubricating oil Y components by indirect heat exchange with hot oil products escaping from said coking operation, materially reducing the pressure below atmospheric pressure and vaporizing lubricating oil stock from the thus heated oil under sub-atmospheric pressure, and supplying residual stock from the subatmospheric vaporizing operation to the coking operation.

2. In an operation combining the separation of lubricating oil components :from crude stocks containing the same and the production of a cracked distillate product, the improvement which comprises reducing residual stock to coke by direct introduction into the oil to be coked of hot oil products direct from a vapor phase cracking operation, heating a crude stock containing lubricating oil components by indirect heat exchange with hot oil products escaping from said coking operation, materially reducing the pressure below atmospheric pressure and vaporizing lubricating oil stock from the thus heated oil under sub-atmospheric pressure, supplying residual stock from the subatmospheric vaporizing operation to the coking operation, condensing a gas oil stock from the hot oil products escaping from said coking operation and supplying such condensate to the vapor phase cracking operation.

In testimony whereof I affix my signature.