US2151691A - Process for treating hydrocarbon oils - Google Patents

Description

Patented Mar. 28, 1939 UNITED STATES FATENT OFFICE PROCESS FOR TREATING HYDROCARBON OILS tion of Virginia Application April 4, 1932, Serial No. 602,969

4 Claims.

This invention relates to a process of cracking hydrocarbon oils in such a manner that motor fuels are obtained which contain anti-detonating compounds. The process is applicable to crude petroleum, oils and other crude hydrocarbons, such as blast furnace tar, coke house tar and hydrocarbons obtained by the destructive distillation of coal and wood, as well as the distillates and residues of such products. By this invention heat is applied to the oils or hydrocarbons in such a manner that anti-detonating motor fuels are produced together with other products which may be converted in large part into antidetonat ing motor fuels. At the same time gases and other liquid products, as well as solid residues are produced. This application is a continuation in part of the applicants earlier application Serial No. 491,101, filed October 25, 1930, for Combined liquid phase and vapor phase oil cracking process. The application Serial No. 491,101, discloses a combined cracking process in which vapors from the cracking operation separated out in an enlarged separating Zone are passed through a plurality of fractionating zones in which a series of fractional condensates are 'formed of higher boiling point than the desired gasoline product. A portion of the very heavy condensate is returned to the separating zone while other reflux condensates are separately cracked in cracking coils which discharge into the enlarged separating chamber. The lighter condensate is subjected to a higher temperature than the heavier condensate. Preheated heavy oil is mixed with the transfer products from one of the coils and discharged into the enlarged separating zone in contact with the vapors and liquids therein.

An arrangement of apparatus is somewhat diagrammatically shown in the accompanying drawing by which the invention may be carried out.

In the drawing reference character i indicates a storage tank for crude or reduced petroleum oils, for example. A pipe line 2 in which a pump 3 is located leads from the tank i through heat exchangers 4, 5 and E to the tubular heating r elements or coil 1 located in the furnace 8.

Valved bypasses 9, II) and II may be provided in the pipe line 2 around the heat exchangers 4, 5 and 6 so that any desired portion of the material from the tank I may be passed to the heating coil 'I Without passing through the heat exchangers 4, 5 and B. A pipe line i2 Vleads from the `coil 'I to a receiver I3.

An outlet I4 for the heavy residues from the receiver ISleads `to an evaporator I5. An outlet I6 for coke or heavy residue is provided at the bottom of the evaporator I5.

A vapor outlet II extends from the upper portion of the evaporator l5 to the partial condenser I8. A condensate outlet pipe I9 leads from the lower portion of the condenser IB through the cooler to the reservoir El. A pump 22 is provided in the outlet 23 from the reservoir 2l. The outlet 23 is divided into Valved branches, one of which may lead toa storage tank and the other to the pipe 24 which leads back to the receiver I3.

A vapor outlet pipe 25 leads from the receiver I3 to the rst one of a series of heat exchangers of direct or indirect contact type. Four of these exchangers 251, 262, 263 and 264 are illustrated, although this number may be varied. The pipe 25 leads from the last heat exchanger of the series to a fractionating column 2l of the well known sort. Valved outlet pipes 2,81, 232, 283, and 284 lead from the heat exchangers 251, 232, 263 and 2,64 to the pipe 28 which is provided with valves so that the material entering it can be passed to the receiver I3 or the evaporator I5 or the fractionating column 2l, or selected portions may be diverted respectively to Whichever of these receptacles as is desired.

An outlet pipe 29 for the heavy fraction from the fractionating column 2'I is provided with a pump 3U and leads to the heating device o-r coil 3l 30 through heat exchangers such as 234 and 231, for example. An outlet pipe 32 leads from the coil 3| to the pipe I2.

A vapor pipe 33 extends from the fractionating column 21 to the heat exchanger 5 and thence to a fractionating column 34 similar to the rst one. A vapor pipe 35 extends from the fractionating column 34 to the heat exchanger 4 and thence to the condenser 35.

An outlet pipe 31 for condensates from the column 34 leads to a reservoir 38 from which an outlet pipe provided with a pump 39 leads to a pipe 4I) which leads to the heating element or coil 4I inthe furnace 42.

A storage tank 43 is provided which may contain gas oil. A pipe 44 provided with a pump 45 is also provided with branches 46, 4l, 43 and 49 leading respectively to the fractionating column 34,A fractionating column 21, pipe 2, and pipe I2.

A storage tank 50 is provided which may contain kerosene or heavy naphtha. A pipe 5I pro vided with pumps 52 and 52 leads from the tank 50 through the heat exchangers 263 and 232, with a Valved bypass 5I' around them, to tubular heating elements or coil 54 in the furnace 42. The

outlet 55 from the coil 54 leads to the pipe I2. A valved branch line 53 leads from the pump 52 to the reservoir 38 so that all or a portion of the material from tank 58 or pipe line 24 may be passed either through line or line 53.

A pipe 51 from any convenient source of superheated steam extends into the evaporator I5. The steam may be superheated to a temperature of about 1000 F. The pipe lines 48 and 55 are connected by valved connections to the steam pipe 51.

A valved branch pipe 58 extends from the outL let pipe I4 from the receiver I3 to a cooler` 59. An outlet pipe 60 provided with a pump 6I extends from the cooler 59 to a storage tank (not shown) and a valved branch pipe 62 is connected from the pipe 60 to the pipe I4 near the evaporator I5. A valved pipe 63 extends from the lower portion of the evaporator I5 to the pipe 63.

A vapor outlet pipe 64 extends from the partial condenser I8 to a secondary condenser 65 from which a condensate outlet pipe 66 leads to a reservoir 61. A valved outlet pipe 68 leads from the reservoir 61 and an outlet pipe 69 provided with a pump 10 also leads away from this reservoir 61'. The outlet 1I of the pump is divided into valved branches one of which leads to a storage tank and the other one to the pim 24. An outlet pipe 12 for uncondensed gases leads from the condenser 65 to a pressure pump 13 and thence to a gas storage tank (not shown).

An uncondensed gas pipe 14 also leads from the condenser 36 to the pipe 12. An outlet pipe 15 for condensates leads from the condenser 36 to the cooler 16 from which a pipe 11 leads to the reservoir 18. An outlet pipe19 provided with a pump 80 leads away from the reservoir 18. A gas pipe 8I leads from the reservoir 18 to the pipe 12. A pipe 82 provided with a pump 83 leads from the pipe 15 to the fractionating column 34.

A pipe line 84 provided with a pump 85 passes hot fuel oil from receiver I3 through heat exchanger 6 thence to pipe I4. Pipes 81 and 86 return condensates from heat exchangers 5 and 4 to fractionating columns 21 and 34 respectively.

Valves are indicated in the various pipes at appropriate locations by crosses so that the apparatus can be manipulated in accordance with the desired conditions of operation.

The following are given as specific examples of carrying out the invention with the arrangement of apparatus shown on the drawing,'but it is to be understood that lthe invention is not restricted to these particular. examples:

Reduced crude oil such as the fraction having an initial boiling point of about 300 F. and an end boiling point of about 850 F. from which light fractions have been distilled off is supplied to the tank I from which it is passed through the pipe 2 by the pump 3 through the heat exchangers 4, 5 and 8 to the heating coil 1 which it reaches at a temperature of about '700 F. It passes through the coil 1 in about 4 to 5 minutes and leaves this coil at a temperature of about 850 F. and passes to the receiver I3 through a common pipe I2, together with material from coil 4I or 54, or both.

Within the receiver I3 there results a separation of material entering into a vapor portion passing out through pipe 25 and a liquid portion passing out through pump 85, through heat exchanger 6 into line I4. The vapors passing out through the pipe 25 are partially condensed in the heat exchangers 261, 282, 263 and 264 from which the condensates are withdrawn to the pipe 28. The remaining vapors pass to the fractionating column 21. The condensates from the column 21 having an initial boiling point of 350 F., and a final boiling point of 750 F. are passed through one or more of the heat exchangers 261 to 284 to the coil 3I which they reach at a temperature of about 700 F. They pass through this coil in about 12 to 14 minutes and leave it at -a temperature of about 860 F. to 910 F. and thence to the receiver I 3.

The vapors leaving the fractionating column 21 pass through the heat exchanger 5 and thence to the fractionating column 38. The condensate from the column 34 having an initial boiling point of about 350 F. and a nal boiling point of about 700 F. passes into the receiver 38 and thence through the line 5I and heat exchangers to the coil 54 which it reaches at a temperature of about 700 F. taking about 15 to 20 minutes to pass through, leaving this coil at a temperature of about 920 F. to 980 F., from which it passes to the receiver I3. Or, a fraction or all of it may be diverted to a line 51 and thence to the evaporator I5.

Also, part of the material from the receiver 38 may be passed through pump 39 into line 48 along with some fixed gases from the process to the heating coil 4I, which they reach at a temperature of about 400 F. taking about 30 minutes to pass through this coil. They leave this coil at about a temperature of 975 F. to 1150 F. and pass through the pipes 55 and I2 into the receiver I3, or an elux from the coil 4I or a portion thereof may be diverted through line 51 to the evaporator I5.

The vapors leaving the fractionating column 34 pass through the heater 4 to the condenser 36. The uncondensed gases pass from the condenser 38 through the pipe 14 to the pipe 12 and pressure pump 13 and thence to a gas storage tank. Condensates having an initial boiling point of 90 F., an end point of 450 F. pass through the outlet 15 to the cooler 16 and thence to tne receiver 18 from which they pass to a storage tank through the pipe 19. Uncondensed gases from receiver 18 pass through the pipe BI to the pipe 12. A portion of the condensates leaving the condenser 36 may be passed by means of the pump 83 back into the fractionating column 34. Y

The condensates from the heat exchangers 261, 262, 263 and 254 vary in their gravities and boiling points, the heaviest ones being from the earlier heat exchangers in the series. In actual runs the boiling point of the condensates passing out through the outlet 281 have been found to have an initial boiling point of 440 F. and an end boiling point of 738 F., and a gravity range ing from 10 B. to 18 B.; those from 282 having a ranging boiling point from 406 F, to 700 F. with specific gravity in range from 12 B. to 19 B.; those from 28s having a boiling range of 320 F. to '700 F. and a gravity range of 16 to 22 B. and those from 284 having a boiling range from 230 F. to 700 F. with a gravity from 16 B. to 24 B.

By manipulation of the valves in the pipe 28 such a portion of these condensates as is desired is returned to the receiver I3 and the remaining portion is passed to the fractionating column 21. The portions returned to the receiver I3 are in general the heavier portions and they serve in this receiver I3 for at least two purposes. One is to absorb excess heat that had been furnished by the furnaces 3 and 42, and the other is to permit of the conversion of these condensates into materials of a desired type through admixture with the high temperature vapors from the coils heated by the furnaces 8 and 42. l A

The portion of the condensates from theheat exchangers which reach the pipe 23 and are passed to the column 27 are ingeneral the lower boiling portions resulting from tWo sources, namely the re-boiling of the condensates diverted to the receiver I3 and the light fractions from the vapors entering the receiver I3 through line I2.

If condensates reaching the pipe 28 are found to bevalueless or harmful for producing antidetonating fuels they can be diverted by manipulation of the valves to pass either to the 'evaporator I5 or out of the system throughthe pipe 60.

With this system of apparatus, starting with reduced crude oil, the valves may be manipulated when desired in such a manner that all or a portion of the condensates reaching the pipe 28 can be passed into the evaporator I5. This may be desirable, for example, When it has been found by analyses of these condensates that so much of the hydrogen has been removed that it is inadvisable to return them to the receiver I3. When they are passed to the evaporator I5 they are therein cracked by the high temperature products received through the line 57 and as a result coke or extraordinarily heavy residues are produced and can be Withdrawn through the outlet I3 while anti-detonating products and intermediate products suitable for the production of antidetonating products are simultaneously produced and pass out through the pipe I'I.

In carrying out this invention condensates leaving the condenser I8 have been found to have an initial boiling point of 288 F. and final boiling point of 800o F. and a gravity range of about 8 B. to about 18 B. The condensates from the condenser 65 had an initial boiling point of 150 F. and nal boiling point of 640 F. With gravity range from about 30 B. to about 50 B.

When treating reduced crude as described above it is sometimes found desirable to introduce some gas oil from the tank 43. This may be done by passing some gas oil having an initial boiling point of 350 F. and a nal boiling point of 750 F. through the pipes 4E, 41 and 49 to the fractionating columns 34 and 21 and to the receiver I3 through vapor line I2. The products from this gas oil thereby become distributed in the system, thus making it more iiexible in operation.

Also, it may be advantageous to introduce into the system kerosene or heavy naphtha, or condensates from the condensers I8 and 65. The kerosene or heavy naphthas may have been btained from crude oil which was the source of the reduced crude in the tank I. In such case the kerosene, etc., is introduced into the system either through the line 53 and receiver 38, or through the line I and heating coil 54 in such a manner 'f' that the light boiling fractions contained therein and of known poor anti-detonating characteristics will be so reacted upon by temperatures within the system that anti-detonating compounds are produced therefrom in abundance.

Another example of carrying out the invention will be described starting with gas oil which may be introduced into the tank 43. The gas oil is passed from the tank 43 through the pipe 44 by means of the pump 45. A portion or all of this gas oil may be introduced through the pipes 4B and 41 into the fractionating columns 34 and 21.

The gas oil, or the portion thereof that is not introduced into the columns 34 and 2'! may be passed through the pipes i9 and I2 into the receiver I3. On the other hand, When its composition is such as to make it desirable to subject it to heat before passing into the receiver I3 it may be passed through the heating coil l and thence through the pipe I2 into the receiver I3. Constituents in this gas oil which would make such heating desirable are heavy paraffin fractions or heavy tarry fractions Which need to be heat treated before they enter the receiver I3.

The operation from the receiver I3 is similar to that already described in that condensates from the heat exchangers 261, 262, 263 and 234 may be re-circulated to the receiver I3 or pass to the column 2l, or to the evaporator I5, or out through the line 50, depending upon the same factors as already explained. In a similar Way reduced crudes from the tank I and kerosene or heavy naphthas from the tank 50 may be introduced into the system when gas oil is being treated as just described, thus utilizing the reduced crude and/or kerosene for the production of additional anti-detonating compounds.

Whether reduced crude or gas oil is `the ma-in portion of the hydrocarbon that is undergoing treatment by this process, fixed gases may be passed through the pipe 40 and coil 4I into the receiver I3 or evaporator I5, and condensates from the condensers and 05 may be returned through the pipes 24 and I2 to the receiver I3 or through the pipe 24 to receiver 3B, or pipe line 5I. or tank 50.

It has been found in operating the process that the pressure in the coil I should be kept at about 150 to 400 pounds per square inch; that the pressure in coil 3| should be kept at about 400 to 700 pounds per square inch; that the pressure in the coil 4I should be kept at about 100 to 300 pounds and that the pressure in the coil 54 should be kept at about 700 to 1000 pounds per square inch. 'Ihe pressure inthe receiver I3, fractionating columns 2l and 34 should be about 30 to 60 pounds per square inch; and the pressure in the evaporator I5 may range from about 25 inches of mercury to 60 pounds per square inch.

The gas which passes through the pipe 40 may be from the system or from the gas storage tank, or it may be natural gas or industrial hydrocarbon gases.

I claim:

1. The process of cracking hydrocarbon oils for the production of anti-detonating motor fuel, which comprises heating the oil to be cracked in a confined stream of restricted cross section in a heating Zone and subjecting the stream of oil passing therethrough to cracking conditions of temperature and pressure, passing the stream ol cracked oil into an enlarged vapor-liquid separating zone, fractionating the vapors produced in said heating and cracking operation as discharged from said enlarged separating zone to separate out said anti-detonating motor fuel product and produce a plurality of fractions of successively higher boiling point, discharging the highest boiling point fraction thus separated directly into an enlarged coking chamber in which it is heated and converted into solid coke and cracked oil vapors, separately fractionating the vapors from` the coking chamber, passing a lower boiling point fraction of said fractions in a conned stream through a heating zone and heating it to a high cracking temperature to effect conversion thereof into lower boiling products and discharging the resulting highly heated products into said enlarged coking zone to aid in the coking of said higher boiling fraction.

2. The process defined by claim 1 in which the hydrogen content of said higher boiling fractions is determined and in which the fraction containing the lowest proportionof hydrogen is selected and introduced into said enlarged coking zone.

3. The process of cracking hydrocarbon oils for the production of antidetonating motor fuel which comprises, heating a relatively heavy oil .of the type of topped crude oil while passing the same with a suilicient quantity of a relatively cooler oil, discharging the resulting combined mixture into an enlarged vapor liquid separating zone in which vapors are separated from unvaporized residual oil constituents, fractionating the separated vapors in a plurality of fractionating zones to produce a series of fractional reflux condensates of higher boiling point than the desired motor fuel product, recovering the desired motor fuel product from said vapors, discharging the unvaporized residue from said enlarged separating zone into an enlarged coking chamber and therein coking the said residue at a relatively low pressure and high temperature, introducing one of the higher boiling of said fractional condensates into said coking chamber to be coked therein with said residue, and separately fractionating the vapors produced in the enlarged coking chamber.

4. The process of cracking hydrocarbon oils as dened by claim l in which the liquid oil residue separated out in said enlarged vapor-liquid sep arating zone is passed into said enlarged coking chamber and therein heated and converted into solid coke and cracked oil vapors.

BUTLER P. CRITTENDEN.

Images