US2121209A - Treatment of hydrocarbon oil - Google Patents

Description

June 21, 1938. w. F. MOORE 2,121,209

' TREATMENT OF HYDROCARBON OIL Filed April 19, 1933 INVENTOR W/LLHM E MOORE twww. 7%

128 Y ATTORNEY Patented June 21, 1938 UNITED STATES PATENT OFFICE 2,121,209 TREATMENT or nrnnoomon on. William F. Moore, Bayside, N. Y., as sig nor to Gasoline Products Company, Inc., Newark, 'N. J., a corporation of Delaware Application April 19, 1933, Serial No. 666,801

Claims. (01. 196-49) This invention relates to the treatment of hydrocarbon oil, such as petroleum and oils derived from petroleum, for the recovery therefrom of valuable low-boiling oils such as gaso- 5 lineor motor fuel. My invention has for an object the provisionpf a process adapted to obtain a maximum conversion of a petroleum oil into valuable products more especially low-boiling products such as gasoline or motor fuel, and

to produce reduced amounts of relatively less valuable products such as gas and fuel oil or tar.

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

My invention contemplates a combined process wherein a petroleum oil, for example, a crude petroleum, may be distilled, with the selective 7 treatment of various products of the distillation,

' including pyrolysis or cracking of a suitable stock or stocks resulting from the distillation step, and further selective treatment and combination, under conditions favorable for inter-reaction and the formation of valuable products, of products 0 produced in the distilling and. cracking operations, as well as materials such as gas or oil which may be drawn from outside sources.

More specifically, in one of its aspects my invention contemplates the reforming of gasoline or naphtha of relatively low anti-knock value to produce a gasoline or naphtha product of im- H 45 inter-reaction to take place between the gaseous products of the reforming operation, as well as, when-they are present, gaseous unsaturated hydrocarbons from outside sources, and relatively heavy liquid "constituents also present, thereby resulting in the formation of more or less intermediate products such as motor fuel, naphtha or gasoline or oil suitable for cracking to produce motor fuel or gasoline having an improved antiknock value.

Thus, I may subject a crude petroleum to distillation under substantially non-cracking conditions, the products being separated and fractionated to recover a residual product or reduced crude, gas oil, virgin gasoline and gas, as well as such addition fractions, for example, lubricating oil stocks, as may 'be produced according to the nature of the original crude petroleum. According to one method of operation of my invention the virgin gas oil may then be cracked for the purpose of recovering a cracked gasoline fraction, gases, recycle gas oil, and residual oil or pressure tar, 'The gas oil thus produced may be recycled in the cracking unit. The virgin gasoline from the initial distillation step may then be subjected to heat treatment to effect a reformation of constituents thereof to constituents of improved anti-knock value, while the reduced crude resulting from the initial distillation operation may be subjected to a mild cracking temperature which may promote the formation of unsaturated or other reaction constituents,

and the hot reformed products together with the products from the cracking of the reduced crude may be discharged into a common reaction zone which may also receive gases drawn 2 from the distillation or cracking stages or fromoutside sources, either with or without pyrolysis at high temperature to promote the formation of unsaturated hydrocarbon constituents.

' 'I'he various products delivered to the common reaction zone aredigested together under con- 'ditions favorable for inter-reaction between gaseous and liquid unsaturated hydrocarbons or other reactive constituents, and preferably within a range of temperature andpressure efiective to promote the polymerization of normally 4 gaseous constituents to normally liquid constituents. The resultant vapors may then be withdrawn and fractionated to recover normally liquid and normally gaseous products therefrom,

more particularly, to effect the recovery of the gasoline or naphtha fraction.

As an alternative mode of procedure, I may subjectthe reduced crude or residual oil resulting from the initial distillation step, together with virgin gas oil, if so desired, to a cracking operation of more or less conventional character for the purpose of producing a cracked gasoline distillate, and the various products resulting from the cracking operation, such, forexample, as gas and residual oil or pressure tar may be combined in a common reaction zone, either with or without preliminary treatment under selectedconditions to promote the formation of reactive constituents such as unsaturated hydrocarbons.

\ constituents therefrom.

I may also supply the gases liberated in the distilling stage, preferably supplemented by gases.

drawn from the cracking stage or from an outside source, to the aforesaid reaction stage, and where such gases contain relatively small amounts of unsaturated constituents, they may be subjected to an initial pyrolysis for the purpose of producing or increasing the amount of unsaturated hydrocarbons such as gaseous olefins.

In order that my invention may be clearly set forth and understood, I now describe, with reference to the drawing accompanying and forming part of this specification, various preferred forms and manners in which my invention may be practiced and embodied, but without limiting my invention to such exemplifications. In this drawing:

The single figure is a more or less diagrammatic view of a system for treating hydrocarbon oil in accordance with my invention.

Referring to the drawing, a petroleum oil, such, for example as a crude petroleum of Midcontinent origin, is drawn from a source (not shown) through a conduit I, wherein is located a pump 2, by means of which the oil may be passed to a heat-exchange coil 3 located Within a fractionating tower 4, before passing through a conduit 5 to heating coils 6 and 'I located within a furnace 8.

While in transit through the coils 6 and I, the oil is heated to a suflicient temperature to effect the desired distillation, such for example, as from 600 to 750 F., and the heating of the oil may with advantage be conducted without any material cracking. The heated oil then flows through a line 9 having a pressure-reducing valve In to a separating compartment II located in the bottom of the fractionating tower 4. The separating compartment I I may be provided with suitable baflies I2, as well as a reflux supply line I3, for the purpose of preventing entrainment-of heavy or residual constituents of the oil being distilled. The vapors liberated in the separatingcompartment; II pass upward through a trapout tray I4 into the upper portion of the fractionating tower 4, which is provided with suitable plates or trays I5, and under the influence of the heat-exchange coil 3, a dephlegmating and fractionating action takes place, resulting in the condensation of a gas oil fraction which collects at the trap-out tray I4 and is withdrawn from the fractionating tower 4 through a conduit I6 having a valve I1 and a pump I8.

The gases and vapors reaching the top of the fractionating tower 4 pass through a vapor line 2I, a condenser 22 and a condensate line 23 to a gas separator 24, where a separation of condensate and uncondensible gas is effected. The gases are withdrawn through a conduit 25 having a valve 26 while the condensate, consisting of virgin gasoline, is withdrawn through a conduit 21 having a valve 28.

A portion of the gas oil withdrawn from the trap-out tray I4 may be employed as a reflux either in the tower 4 or elsewhere. Thus, a portion of this gas oil may be withdrawn through a branch conduit 3| having a valve 32 and com municating with the conduit I6, to pass through a cooler 33 and a conduit 34 having a valve 35, to the reflux line I3, by means of which this oil may be reintroduced into the separating chamber II.

The virgin gas oil not employed as a reflux may be delivered by the pump I8 through a conduit 36 having a valve 31, while the residual oil or reduced crude which separates in the bottom of the separating compartment II may be withdrawn therefrom from a conduit 38 wherein is located a pump 39.

In the drawing, I have illustrated a cracking plant comprising principally a furnace M, a still 42 and a fractionating tower 43, which plant may be employed for cracking either virgin gas oil or reduced crude, or both. Thus, the virgin gas oil may be delivered by the pump I8 through conduits I6, 36, 44 and 45 to heating coils 46, 41 and 48 located within the furnace 4I, wherein the gas oil is heated to any suitable cracking temperature such, for example, as from 850 to 1050 F. under such superatmospheric pressure as may be desired. When using a very clean -stock the cracking may be carried on in the vapor phase. The resultant hot cracked products are then discharged through a transfer-line 5| to the still 42, which may receive reduced crude from the pump 39 and conduit 38 through a branch conduit 52 having a valve 53 and leading to-an intermediate portion of the still 42. The still 42 may be provided, as shown, with bafiies 54 and may also receive cool reflux oil, preferably at a point above the point of admission of the reduced crude thereto. For example, such reflux oil may be supplied from the pump I8 and the cooler 33 through a conduit 55 having a valve 56.

Within the still 42, separation of vapors and residual oil takes place, the vapors passing through a vapor line 51 to the fractionating tower 43, while the residual liquid is withdrawn from the bottom of the still 42 through a conduit 58 wherein is located a pump 59 and a valve 60. In some instances, as for example when reduced crude is not charged to the still 42, it may be desirable to withdraw the residual oil or pressure tar from the bottom of the still 42 to remove it from the system. In other instances, such residual oil may be withdrawn through a branch conduit I52 having a valve 63.

Within the fractionating tower 43, which is preferably provided with plates or trays 64 and a cooling coil 65, the vapors withdrawn from the still 42 are subjected to a fractional condensation, which is carried out in such manner as to effect the condensation and accumulation at the bottom of the fractionating'tower 43 of a gas-oil fraction which is preferably withdrawn from the tower 43 through a conduit 66 having a valve 61 and a pump 68. This gas oil may be recycled through the coils 46, 4'! and 48 lo-' cated within the furnace 4!. Gases and vapors reaching the top of the fractionating tower 43 are withdrawn through a vapor line II to a condenser I2 from which the condensed products pass through a conduit I3 to a gas separator I4. The condensate, consisting of light cracked distillate or gasoline, is withdrawn from the separator I4 through a conduit 15 having a valve 16, but a portion of this condensate may be returned, if desired, through a branch line 11 having a valve"!!! and a pump 19 and returned to the upper portion of the fractionating tower 43 as reflux.

The tower 43 is preferably provided at an intermediate point with a trap-out tray 8I so located as to make possible the withdrawal of a side stream consisting of a heavy gasoline fraction suitable for reforming purposes. This side streamis withdrawn from the trapout tray BI through a conduit 82 having a valved branch conduit 83 leading to a lower point in the tower 43 and a branch conduit 84 having a valve 85 and a pump 80.

Gases withdrawn from the separator 14 may be delivered to a fuel gas main or elsewhere through a pipe 80 having a valve 00, or may be diverted through a branch conduit 9i having a valve 92 and a gas pump 93.

From the foregoing it will be apparent that I have provided a combined stripping and cracking system which may variously be operated to produce virgin gas, gasoline and residual oil or reduced crude, as well as cracked gases, cracked jected to a reforming operation.

As stated hereinabove, my invention contemplates, the selective treatment of a desired number of such products, together with the ultimate combination of such stocks or the products resulting fromthe treatment of such stocks, under conditions favorable for polymerization and reaction to produce valuable low-boiling petroleum 'oils, While it will be apparent that I may variously accomplish the selective treatment of the stocks, in the present instance I have illustrated a preferred system which includes a furnace I00 provided with separate radiant heating coils I M and I02 and convection heating coil I03, the products from which are delivered to a common reaction chamber I05, through transfer lines I00, I07 and I08, respectively.

In the instance illustrated in the drawing th radiant heating coil IOI is employed for the purpose of effecting the reformation or conversion. of constituents of gasoline or naphtha to constituents of increased anti-knock value. Virgin gasoline from the separator 24 may be delivered to the coil IOI through a conduit IIO having a valve III and a pump II2, a conduit II3, and a conduit II4 having a valve H5. The heavy gasoline fraction withdrawn as a side stream from the trap-out tray BI in the fractionating tower 43 may also be delivered to the coil IIlI through a conduit 84 by means of the pump 80, and the conduits II3 and-I I4. Naphtha or gasoline from an outside source may also be delivered to the coil I0! by means of a conduit IIii, wherein is located a pump Ill and a valve IIO. Any of the aforesaid gasolines or naphthas may be employed alone or in any desired combination. I

While in transit through the coil IOI, the naphtha or gasoline is heated to a temperature of for example, from 850 F. to 1000" F; or even higher, under'a suitable elevated pressure of, for example, from 200 to 750 pounds per square inch. Higher pressures of the order of 1000- 1200 pounds may be usedwith advantage. The

hot reformed products then pass through the transfer line I06 to the reaction vessel I05.

At the same time relatively heavy hydrocarbon oil, preferably of residual character and preferably containing unsaturated hydrocarbon or other reactive constituents, is delivered to the reaction vessel I05. Pressure tar withdrawn from the bottom of the still 42 may be delivered directly to the reaction vessel I through the conduit 58 and a branch conduit I having a valve I2I. Reduced crude withdrawn'from the separating compartment II of the fractionation tower 4 may be forced by the pump 39 through the conduit 38 and through a line I22 having valves I23 and I24 to the convection heating coil While in transit through the coil I03 the oil is preferably heated to a mild cracking temperature the pump 59 to the conduit 58, a conduit I having a valve I3I and a conduit I22 to the coil I03. The aforesaid stocks may be used either separately or in any desired combination.

If desired, gasoline or' naphtha from the senarator 24 or the trap-out tray BI or both may be withdrawn from the conduit II'3 through a branch conduit I32 having a valve I33 and communicating with the conduit I 22, for the purpose of commingling with and diluting the heavy hydrocarbon oil introduced into the coil I03 and for the further purpose of making it possible to carry somewhathigher temperatures in the coil I03 than would otherwise be possible.

The oil while in transit through the coil I03 is, as aforesaid, heated to a mild cracking temperature to reduce the viscosity of the oil and to effect a mild cracking with the result that the content of unsaturated hydrocarbon or other reactive constituents in the oil may be increased and the products from the coil I03 are rendered more suitable for reaction and combination with other constituents under the conditions which obtain in the reaction vessel I05.

The coil I02 is preferably employed for the purpose of eifectinga preliminary pyrolysis of gaseous hydrocarbons to promote the formation of gaseous unsaturated hydrocarbons, such as gaseous olefins, which are then delivered to the reaction vessel I05 through the transfer line I01. Thus gas liberated in the separator 24 may be withdrawn through a conduit I having a valve MI and a gas pump I42, bymeans of which the gas is forced through the coil I02. Communicating with the conduit I40, I provide a gas conduit I43 having a valve I44 which may receive hydrocarbon gas from an outside source through a conduit I45, wherein is located a gas pump I46. By means of the conduits I45, I43 and I40 any hydrocarbon gas suitable for pyrolysis to effect formation of unsaturated hydrocarbon constituents may be introduced into the coil I02. gas containing such constituents as ethane, propane, butane, pentane, ethylene, propylene and the like. While in transit through the coil I02, such gases are heated to a high cracking temperature' of, for example, from 1100 to 1700 F.,

Thus I may employ natural gas or other under a suitably elevated pressure of, for example, from 200 to 750 pounds per square inch or even higher, and the resultant pyrolized gases are then delivered through the transfer line I01 to the reaction vessel I05.

Where the hydrocarbon gases to be delivered to the reaction vessel I already contain suflicient quantities of gaseous olefins or the like, they may be delivered directly to the reaction vessel I05 without-preliminary pyrolysis in the coil I02. Thus, cracked hydrocarbon gases from the gas separator 14 may be withdrawn through the conduit 9| and delivered by means of the gas pump 93 directly to the reaction vessel I05. Furthermore, gases introduced into the system by means of the gas pump I46 may pass through the conduit I45 and a branch conduit I5I having a valve I52 directly into the reaction vessel I05.

While various types of reaction vessels may be employed, the reaction vessel I05 illustrated in the drawing represents the preferred type. This vessel comprises a more or less elongated vertical shell having an interiorly disposed annular bafile I55 which separates the interior of the vessel I05 into an annular compartment I56 and an inner compartment I51, which compartments I56 and I51 intercommunicate in the upper portion of the vessel I05. The various hydrocarbons to be reacted together in the vessel I05 are pref erably introduced into the lower portion of the outer compartment I56 and pass upwardly through the latter before passing downwardly through the inner compartment I51. The products are then withdrawn through a conduit I58 having a valve I59 for delivery to an evaporator section I6I located within a fractionating tower I62. Conduits I58 having valves I59 and communicating with the conduit I58 may also be provided for the purpose of limiting or preventing accumulation of liquid products in the lower portion of the outer compartment I56.

The reaction vessel I05 is preferably maintained at a temperature effective to promote polymerization of normally gaseous hydrocarbons to normally liquid hydrocarbons and interaction between the various unsaturated hydrocarbon or other reactive constituents which may be present, for example, at a temperature of 150 to 900 F. and under a pressure of from 200 to 750 pounds 'per square inch or even higher, for example from 1000 to 2000 pounds per square inch. As polymerization is favored by high pressure, it is, of course, desirable to maintain as high a pressure in the reaction vessel I05 as possible andin practice this pressure is limited only by the pressures which it is possible to maintain in the coils IIII, I02 and I03 from which the various products are delivered to the reaction vessel I05.

The products leaving the reaction vessel I 05, in passing through the conduit I58 to the evaporator section I6I are preferably considerably reduced in pressure by means of the valve I59 for example, to a pressure of from 50 .to 200 pounds per square inch, and upon reaching the relatively low-pressure evaporator section I6I, a separation of liquid and vapors occurs, the liquid being withdrawn from the bottom of the evaporator section I6I through a conduit I63 having a valve I64 while-the vapors pass upward around a plurality of baffles I65 and through a trap-out tray I66 into'the upper portion of the fractionating tower I62 which is provided as shown with a plurality of plates or trays I61.

By means of cooled reflux oil introduced into the upper portion of the fractionating tower I62 through a conduit I68 or by means of cooling effected in any other suitable manner, the vapors passing upward through the fractionating tower I62 are subjected to a fractional condensation to such an extent as to make possible the separation therefrom in liquid form of normally liquid products heavier than gasoline, that is to say, an intermediate or gas oil fraction, which is withdrawn from the trap-out tray I66 through a conduit I having a valved branch conduit HI and a valved branch conduit I12 wherein is located a pump I13.

This gas oil may be removed from the system through the conduit IN or, under the influence of the pump I13, may be recycled, either through a line I14 having valves I and I16 to the conduit 45 and thence into the coils 46, 41, and 48, or through a line I11 having valves I18 and I19 to the conduit I22 and thence into the coil I03. In the latter instance, the gas oil is employed as a diluent for the relatively heavy oil passing through the coil I03.

The gases and vapors remaining uncondensed at the top of the fractionating tower I62 are passed through ,a vapor line I80 to a condenser I8I and through a condensate line I82 to a gas separator I83. The condensate, consisting of naphtha or gasoline, is withdrawn from the separator I83 through a conduit I84 having a valve I65. A portion of this condensate may, however, be diverted from the conduit I84 through the reflux line I68, wherein is located a valve I86 and a reflux pump I81, to be delivered to the top of the fractionating tower I62.

The gases passing out of the separate I83 may be removed from the system through a conduit I90 having a valve I9I, or may be diverted in part through a branch line I92, having a valve I93 and a gas pump I94 to the conduit I40 to be recycled through the coil I02 for further pyrolysis.

It will be apparent to those skilled in the art that, while I'have described hereinabove various preferred methods whereby a petroleum oil may be distilled, with the selective treatment of the various products, and whereby petroleum products resulting from cracking of gases, reforming of naphtha and the cracking of heavy oil may be digested together under conditions favorable for the promotion of inter-reactions between reactive constituents of such materials, my process is not limited to such e'xemplification, but may be varied in accordance with the character of the materials treated and the nature of the results desired, within the scope of the claims hereinafter made.

I claim:

1. The process of treating a petroleum oil which comprises introducing said oil into a distillation zone receiving hot cracked vapors, sep arately withdrawing residual oil and vapors from said zone, fractionating said vapors to separately recover therefrom normally gaseous hydrocarbons, a light gasoline fraction, a heavy gasoline fraction and a heavier gas-oil fraction, independently subjecting said gas-oil fraction to a cracking temperature while in transit through a heating zone and discharging the resultant hot products into said distillation zone to supply said hot cracked vapors, subjecting said heavy gasoline fraction to conditions of temperature and pressure in a separate heating zone effective to promote reformation of constituents of said heavy gasoline fraction to constituents of increased anti-knock value, reacting the hot reformed products and normally gaseous hydrocarbons obtained as aforesaid with said residual oil under conditions effective to promote polymerization of gaseous hydrocarbons to normally liquid hydrocarbons, removing resultant products of said last-mentioned reactionand separately fractionating them to recover said normally liquid hydrocarbons.

.2. The process of treating. a petroleum oil which comprises introducing said oil into a distillation zone receiving hot cracked vapors, sep-' arately withdrawing residual oil and vapors from said zone, fractionating said vapors to separately recover therefrom normally gaseous hydrocarbons, a light gasoline fraction, a heavy gasoline fraction and a heavier gas-oil fraction, independently subjecting said gas-oil fraction to a cracking temperature while in transit through a heating zone and discharging the resultant hot products into said distillation zone to supply hot cracked vapors, combining said residual oil, normally gaseous hydrocarbons obtained as aforesaid and said heavy gasoline fraction under conditions. of temperature and pressure effective to promote polymerization of ,gaseous hydrocarbons to normally liquid hydrocarbons, removing resultant products and separately fractionating them to recover a gasoline fraction therefrom.

3. The process of treating petroleum oil which comprises introducing said oil into a distillation zone receiving hot cracked vapors, separately withdrawing residual oil from said zone, fractionating vapors obtained from said zone to separately recover therefrom normally gaseous hydrocarbons, a gasoline fraction and a gas-oil fraction, independently subjecting said gas-oil fraction to a cracking temperature while in, transit through a heating zone and discharging the resultant hot products into said distillation zone to supply said hot cracked vapors, subjecting at least a part of said gasoline fraction to conditions of temperature and pressure in a separate heating zone efiective to promote reformation of constituents of said gasoline fraction to constituents .of increased anti-knock value, reacting the hot reformed products and normally gaseous hydrocarbons obtained as aforesaid with said residual oil under conditions effective to promote polymerization of gaseous hydrocarbons to normally liquid hydrocarbons, removing resultant products from said last-mentioned reaction and separately fractionating them to recover said normally liquid hydrocarbons.

4. The process of treating a petroleum oil which comprises introducing said oil into a distillation zone receiving hot cracked vapors, separately withdrawing residual oil and vapors from said zone, fractionating said vapors to separately recover therefrom normal gaseous hydrocarbons, a gasoline fraction and a heavier gas-oil fraction, independently subjecting said gas-oil fraction to a cracking temperature while in transit through a heating zone and discharging the resultant hot products intosaid distillation zone to supply said hot cracked vapors, combining said residual oil, normally gaseous hydrocarbons obtained as aforesaid and at least a part of said gasoline fraction under conditions of temperature and pressure effective to promote polymerization of gaseous hydrocarbons to normally liquid hydrocarbons, removing resultant products and separately fractionating them to recover a gasoline fraction therefrom.

5. A process in accordance with claim 4 wherein said residual oil is subjected to mild cracking prior to combining with said normally gaseous hydrocarbons and said gasoline fraction.

WILLIAM F. MOORE.

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