US2036968A - Treatment of hydrocarbon oils - Google Patents

Description

April 7, 1936. w. F. MOORE l TREATMENT OF HYDROCARBON vOILS Filed Feb. l, 1933 INVENTOR- W/LL/AM MOORE BY ADM $4 M ATToRN EY-V Patented Apr. 7, 1936 ITED STATES PATENT OFFICE TREATMENT OF HYDROCARBON lOILS William F. Moore, Bayside, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application February 1, 1933, Serial No. 654,585

11 Claims.

to oils of lower boiling points and coke.

My invention has for an object the provision of an improved process for converting hydrocarbon oil to oils of lower boiling point and coke in which process the maintenance of low pressure conditions and the removal of vapors in the coking stage are facilitated.

My invention has for further objects such additional improvements in operative advantages and results as may hereinafter be found to obtain.

My invention contemplates heating a hydrocarbon oil to cracking temperature under pressure, as, for example, while in transit through a pipe coil, discharging the cracked products into a reaction stage maintained under superatmospheric pressure and from which vapors and liquid are separately removed, passing the vapors to a fractionation zone wherein heavierY constituents of said vapors are condensed and thereby separated from lighter constituents of said vapors, passing liquid oil from the reaction stage to a coking stage maintained under low pressure wherein residual portions of the liquid oil are reduced tol coke, delivering vapors from the low-pressure coking stage to a low-pressure dephlegmation stage wherein a partial condensation is effected, withdrawing vapors fromy said dephlegmation stage and forcing them into the fractionating stage by the energy of the vapors flowing from the reaction stage, and separately withdrawing condensate or residual oil from said dephlegmation stage and delivering it to said fractionation stage. Y

My invention further contemplates the introduction of liquid from the reaction stage into the coking stage at an elevated point and preferably in an atomized condition, and subjecting the liquid thus introduced to contact in the ,cok'ing stage with a portion of the high-pressure vapors from the reaction stage to facilitate the removal of volatile material.

My invention further contemplates recycling condensate recovered in said fractionation stage through a heating coil wherein it is heated to lcracking temperature, and subsequent delivery of the cracked products to the reaction stage, and, where the original oil treated initially contains gasoline or naphtha, the separate heating yof this oil and the discharge of the heated oil into the aforesaid dephlegmation stage where it is stripped of its light constituents. My inventionfurther contemplates the removal of vaporsl from the fractionation stage, which vapors comprise low-boiling constituents such as gasoline or naphtha, and the subsequent condensation 's and recovery of these valuable products.

In order that my invention may be clearly set forth and understood, I now describe, with reference to the drawing accompanying and forming a part of this specification, various preferred forms and manners in which my invention may be practiced and embodied. In this drawing, the single figure is a more or less diagrammatic elevational view of apparatus for converting hydrocarbon oil to oils of lower boiling point and coke in accordance with my present inventiom Referring now to the drawing, a hydrocarbon oil, such, for example, as a gas oil, is drawn` from a charge tank I through a conduit 2 by means of a pump 3 anddelivered through a conduit 4 to a heating coil 5 located in a suitable heating furnace 6. A portion or all of this oil may be diverted through a heat-exchange coil 'I located in the upper portion of a fraction- 25= ating tower 8 by means of conduits I0 and II having valves I 2 and I3, respectively, and by means of a valve I4locatedin the conduit l with which the conduits I0 and II communicate. 'il' I 8 having valves I 9 and 20, respectively, and 35-V` by means of a valve 2l located in the conduit 4 with which the conduits I'I and 18 communicate. In the event that it is desired to pass oil through the coils 'I and I5 in series, the oil leaving the coil 1 may pass through a conduit 23 having a valve 2li, the valves I3 and I9 being closed. It Will be obvious, however, that by manipulation of the valves I2, I3, I4, I9, 20, 2| and 24, as well as the valve 25 located in the inlet to the coil I5, the proportions and amounts of oil ilowing through either of the coils I and I5 may be regulated independently of the oil owing through the other. l

During its transit through the coils 1 and I5 or one of these, the oil may be heated to a tem- 50 perature of from 250 to 500 F. and in this condition flows through the coil 5 where it may be raised to a temperature of from 600 to 700 F. The oil then passes through a conduit 30 having a valve 3| to a second coil 32 located in the fur- 55."

nace 6 where it may be heated to a cracking temperature of, for example, 875 to 1000 F., preferably under a high pressure.

The cracked products then pass through a transfer line 33 which may have a pressurereducing valve 34 to an enlarged reaction chamber 35 preferably maintained under a pressure of from to 400 pounds per square inch or at a pressure substantially equal to that in the coil 32, and preferably at a temperature of from 850 to 950 F. The vapors are withdrawn from the upper portion of the reaction chamber 35 through a vapor line 36 having a Valve 3`| and leading tothe lower portion of the fractionating tower 8, while liquid oil collecting in thebottom of the reaction chamber 35 is withdrawn through a conduit 38 having a pressure-reducing valve 39 and preferably terminating in an atomizing or spraying device 40 located in a coke drum 4|. While a single coke drum is shown in the figure, it will readily be understood by those skilled in the art that a plurality of such drums may be provided to= be used in alternation or rotation, thus providing for the removal of any coking drum ,fromthe system for the purpose of extracting the coke therefrom.

In the coking drum 4|, largely by means of the contained heat in the liquid entering from the reaction chamber 35, theI liquid oil is reduced to coke and the coking action may be facilitated by discharging a portion of the high-pressure vapors from the reaction chamber 35 through a conduit 42 having a valve 43 and communicating with the vapor line 36. In the preferred instance illustrated, the conduit 42 terminates in the lower portion of the coke drum 4| and the highpressure vapors are thus brought into intimate countercurrent contact with the liquid to be coked entering through the atomizing or spraying device 40.

Vapors are withdrawn from the coking drum 4| through a vapor line 45 having a valve 46 and leading to the lower portion of the dephlegmator I6, wherein, by means of cooling effected through the coil I5 or otherwise, a considerable portion of the vapors is condensed and falls to the bottom of the dephlegmator I6, from` which it is withdrawn by means of a pump 41 and a conduit 48 and delivered to the lowerI portion of the fractionating tower 3, preferably at a point above the point of introduction of vapors to the tower 3 through the vapor line 36.

In order to assist in the maintenance of a low pressure, which may, for example, be a subatmospheric pressure, in the coke drum 4| and the dephlegmator I6, and in order to provide for the transfer of the low-pressure vapors from the dephlegmator I6 into the fractionation tower 8, I provide an injector 50 locatedy in the vapor line 36. The injector 50 receives vapors from theA dephlegmator I6 through a conduit 5| and forces; them by means of the energy of the high-pressure vapors flowing through the vapor line 36r into the lower portion of the fractionation tower 8.

The fractionation tower 8 may be of conventional design and may be provided, as is diagrammatically illustrated in the drawing, with a plurality of trays 52 for assisting in the fractionation. By means of cooling effected by the relatively cool oil flowing through the coil 1, or otherwise, the combined vapors passing through the fractionating tower 8 are subjected to a dephlegmating and fractionating action toco-ndense heavier constituents of said vapors and separate them from lighter constituents such as naphtha. The uncondensed vapors reaching the top of the fractionating tower 8 are withdrawn through a vapor line 53 and passed to a condenser 54 where low boiling constituents such as naphtha or gasoline are condensed and the cooled mixture of oil and gas then flows through a conduit 55 having a valve 56 toV a separator 5T from which gas and uncondensed vapors are withdrawn through a conduit 5S, while condensate, for example naphtha, is withdrawn through a conduit 59 having a Valve 66.

The heavier constituents of the vapors passing through the fractionating tower B which are condensed and collect in the bottom of the latter are withdrawn through a conduit 6| having a valve 62 and are delivered by means of a pump 63 located in the conduit 6| to the coil 32 which it may enter at an intermediate point through a branch conduit 64 having a valve 65. The oil thus entering the coil 32 is subjected to cracking temperature along with charge oil separately introduced and is subsequently delivered to the reaction chamber 35.

Where the charge oil initially contains a considerable portion of low-boiling constituents, such for example as naphtha or the like, such low-boiling constituents may be removed by heating the oil to a temperature short of one which would effect material cracking of the oil. Consequently, where this is true, I prefer to pass the charge oil from the coil 5 directly to the dephlegmator I6 by means of a transfer line 66! having a valve 'II and preferably terminating in an atomizing or spraying device 68 located within the upper portion of the dephlegmator I6.

In this instance the valve 3| is closed. The valve 65 may also be closed and the cycle stock withdrawn from the bottom of the fractionating tower 8 may be passed through the conduit Ii and a branch conduit I0 having a Valve 1| into the inlet to the coil 32 and in this manner may be caused to traverse the entire length of the heating coil 32. It will be obvious that in this instance the cycle stock collected in the bottom of the fractionating tower 8 will include residual portions of the stripped charge oil. This procedure may be adopted whenever the charge oil initially contains a considerable portion of lowboiling constituents, but is especially useful when treating a crude petroleum containing such constituents and which has not been subjected to a previous topping or stripping operation for removal of the same.

The pressure maintained in the coil 32 may vary from a pressure merely sufcient to cause the products to flow into the high-pressure reaction chamber 35 to a pressure materially higher than that obtaining in the reaction chamber, for example, a pressure of 1000 pounds per square inch. As has been indicated hereinabove, the pressures maintained in the coking drum 4| and the dephlegmator I6 are relatively very low as compared with the pressures maintained in the reaction chamber 35, and are preferably substantially .atmospheric or even sub-atmospheric in character, whereas the pressures maintained in the fractionating tower 8 may vary from atmospheric pressure to, for example, about 40 pounds per square inch, or whatever pressure is necessary in order to deliver gas into the mains to which it is supplied.

By way of example, the temperatures maintained in the coking drum should not be lower than about 830 F. but may be considerably higher. 'Ihe temperature in the upper portion of the dephlegmator I6 may be from 500 F. to 700 F., while that maintained in the lower portion of the dephlegmator may be from 600 to 800 F. In the ordinary operation of the fractionating tower 8, suicient cooling will be provided to reduce the temperature of the vapors leaving the fractionating tower to from 300 to 400 F. while the oil collecting in the lower portion of the fractionating tower may be at a temperature of from 550 to 650 F. or somewhat higher.

It will be obvious to those skilled in the art that while I have described my invention hereinabove with reference to certain speciiic illustrative details and examples, my invention is not limited to the details of such examples but may variously be embodied in the scope of the claims hereinafter made. l

I claim:

1. The process of converting a hydrocarbon oil to oils of lower boiling points and coke which comprises, heating an oil to a cracking temperature while in transit through a heating coil under high pressure, discharging the cracked stream into a reaction zone maintained under high pressure, separately withdrawing vapors and unvaporized oil from said reaction zone, introducing said oil into a zone of reduced pressure to reduce non-volatile constituents thereof to coke, dephlegmating vapors from said coking zone to recover a fractional condensate therefrom, withdrawing the relatively low-pressure uncondensed vapors from said dephlegmation zone by means of relatively high-pressure vapors from said revture while in transit through a heating coil under high pressure, discharging the cracked 1 stream into a reaction zone maintained under high pressure, separately withdrawing vapors and unvaporized oil from said reaction Zone, introducing said oil into a zone of reduced pressure to reduce non-volatile constitutents thereof to coke, dephlegmating vapors from said coking zone to recover a fractional condensate therefrom, withdrawing condensate oil from said dephlegmation Zone and delivering it to a further dephlegmation zone, separately withdrawing the relatively low-pressure uncondensed vapors from said first-mentioned dephlegmation Zone by means of relatively high-pressure vapors from said reaction zone for delivery to said further dephlegmation zone, and recovering a light distillate fraction and a heavier distillate fraction from the commingled vapors entering said further dephlegmation zone.

3. The process of converting a hydrocarbon oil to oils of lower boiling points and coke which comprises, heating an oil to a cracking temperature while in transit through a heating coil under high pressure, discharging the cracked stream into a reaction zone maintained under high pressure, separately withdrawing vapors and unvaporized oil from said reaction zone, introducing said oil into a zone of reduced pressure to reduce non-volatile constitutents thereof to coke, dephlegmating vapors from said coking zone to recover a fractional condensate therefrom, withdrawing condensate oil from said dephlegmation zone and delivering it to a further dephlegmation zone, separately withdrawing the relatively low-pressure uncondensed vapors from said first-mentioned dephlegmation zone by means of relatively high-pressure vapors from said reaction zone for delivery to said further dephlegmation zone at a point located below the level of unvaporized oil in said further dephlegmation Zone, and recovering a light distillate fraction and a heavier distillate fraction from the commingled vapors entering said further dephlegmation zone. f

4. The process of converting a hydrocarbon cil to oils of lower boiling points and coke which comprises, heating a charge oil to a cracking temperature while in transit through a heating coil under high pressure, discharging the cracked stream into a reaction zone maintained under high pressure, separately withdrawing vapors and unvaporized oil from said reaction zone, in.

troducing said oil into a zone of reduced pressure to reduce non-volatile constitutents thereof to coke, dephlegmating vapors from said coking zone to recover a fractional condensate therefrom, withdrawing the relatively low-pressure uncondensed vapors from said dephlegmation Zone by means of relatively high-pressure vapors from said reaction zone for delivery to a further delphlegmation zone, recovering a light distillate fraction and a heavier distillate fraction from the commingled vapors entering said further dephlegmation zone, and commingling condensate recovered in said dephlegmation Zones with said charge oil prior to discharging the latter into said reaction zone.

5. The process of converting a hydrocarbon oil to oils of lower boiling points and coke which comprises, heating a charge oil to a cracking temperature while in transit through a heating coil under high pressure, discharging the cracked stream into a reaction Zone maintained under high pressure, separately withdrawing vapors and unvaporized oil from said reaction zone, introducing said oil into a zone of reduced pressure to reduce non-volatile constituents thereof to coke, dephlegmating vapors from said coking Zone to recover a fractional condensate therefrom, withdrawing the relatively low-pressure uncondensed vapors from said dephlegmation Zone by means of relatively high-pressure vapors from said reaction zone for delivery to a further dephlegniation zone, recovering a lightI distillate fraction and a heavier distillate fraction from the commingled vapors entering said further dephlegmation zone and commingling condensate recovered in said dephlegmation zones with said charge oil while in transit through said heating coil.

6. The process of converting a hydrocarbon oil to oils cf lower boiling points and coke which comprises, heating an oil toa cracking temperature while in transit through a heating coil under high pressure, discharging the cracked stream into a reaction zone maintained under high pressure, separately withdrawing vapors and unvaporized oil from said reaction zone, introducing said oil and a portion of said vapors into a zone of reduced pressure to reduce nonvolatile constituents thereof to coke, dephlegmating vapors from said coking zone to recover a fractional condensate therefrom, withdrawing the relatively low-pressure uncondensed vapors from said dephlegmation zone by means of a further portion of the relatively high-pressure vapors from s'aid reaction zone for delivery to a further dephlegmation zone, and recovering a light distillate fraction and a heavierl distillate fraction from the commingled vapors entering said further dephlegmation zone.

7. The method of converting hydrocarbon oils to oils of lower boiling point and coke which Vcomprises heating an oil to cracking temperature under relatively high pressure, separately withdrawing vapors from said cracking operation and passing said vapors; directly to a fractionating zone wherein heavier constituents of said vapors are condensed and thereby separated from lighter constituents of said vapors, sepa- A.rately withdrawing unvaporized oil from said cracking operation and passing it to a coking zone maintained at a relatively low pressure, dephlegmating vapors from said low-pressure coking zone in a dephlegmating zone to condense and separate heavier constituents from said vapors, withdrawing and forcing said vapors from said dephlegmating zone directly into said fractionating zone by the energy of the vapors flowing from the high-pressure cracking operation to said fractionating zone.

8. The method of converting hydrocarbon oils to oils of lower boiling point and coke which comprises heating an oil to cracking temperature under relatively high pressure, separately withdrawing vapors from said cracking operation and passing said vapors to a fractionating Zone wherein heavier constituents of said vapors are condensed and thereby separated from lighter constituents of said vapors, separately withdrawing unvaporized oil from said cracking operation and passing it to a. coking Zone main tained at a relatively low pressure, dephlegmating vapors from said low-pressure coking zone to condense and separate heavier constituents from said vapors, forcing said vapors into said fractionating zone by the energy of vapors flowing from the high-pressure cracking operation to said fractionating Zone and delivering said condensed heavier constituents from said dephlegmation zone to said fractionation zone.

9. The process of converting hydrocarbon oil to oils of lower boiling point, which comprises heating said oil to a cracking temperature under superatmospheric pressure, vaporizing a lighter portion of the heated oil at a high pressure, vaporizing a heavier portion of the heated oil at a lower pressure in the presence of a portion of the vapors from said high-pressure vaporisation stage, dephlegmating the vapors from the aoaae est low-'pressure vaporzation stage tolseparate said vapors into a vapor fraction` and a liquid fraction, forcing said vapor fraction by means of the energy of the remaining vapors from the high-pressure vaporization stage into a fractionation zone, delivering said liquid fraction to said fractionation Zone at a point located above the point of vintroduction of the vapors thereto, and withdrawing and condensing dephlegmated vapors from said fractionation zone to recover a light distillate fractionv therefrom.

10. The method of treating hydrocarbon oil which comprises introducing a preheated hydrocarbon oil into a low pressurevdephlegmation zone supplied with hot vapors to eiiect vaporisation of lighter constituents of said oil, separately withdrawing vapors and liquid from said dephlegmation zone and delivering them to a fractionation zone wherein a liquid fraction suitable for cracking is collected, removing said fraction and` heating it to cracking temperature under superatmospheri pressure while in transit through a, heating coil, discharging the cracked products from said coil into an enlarged reaction Zone maintained at high pressure, separately removing vapors and liquid from said reaction zone, passing the vapors into said ractionation zone and passing the liquid to an evaporation zone maintained at relatively low pressure, passing vapors from said evaporation zone into said dephlegmation Zone and forcing low pres'- sure vapors from said dephlegmation zone by means of the energy of the stream of high-pressure vapors flowing from said reaction Zone to said fractionation zone.

11. The process of converting a hydrocarbon koil tooils of lower boiling points and coke which comprises, heating an oil to a cracking temperature while in transit through a heating coil under high pressure, discharging the cracked stream into a reaction zone maintained under high pressure, separately withdrawing vapors and unvaporized oil from said reaction zone, introducing said oil and only a portion of said vapors into a zone of reduced pressure to reduce non-volatile constituents thereof to coke, withdrawing vaporous constituents from said reduced pressure zone by means of a further portion of the relatively high pressure vapors from said reaction zone for delivery to a dephlegmation Zone and recovering a light distillate fraction and a heavier distillate fraction from the cornmingled vapors entering said dephlegmation zone.

WILLIAM F. MOORE.

Images