US2325114A - Hydrocarbon conversion - Google Patents

Description

.July 27, 1943.

. 44 FMP/V451?) J J #3f zi- T (5a-5:11

R. B. DAY ET AL HYDROCARBON CONVERS I ON Filed Aug. 21, l1940 y Patented July 27, 1943 Y UNITED STATES PATENT oFFlcE HYDROCARBON CONVERSION Roland B. Day and Elmer RI.. Kanhofer, Chicago, Ill., assignors to Universal Oil Products Company, Chicago, Ill., a corporation of Dela- Ware Application August 21,1940, SerialNo. 353,519 6 Claims. (Cl. 196-48) accomplished without also decreasing the eifectiveness of the process in some other mannen.

light insuiiciently converted hydrocarbons supplied to the non-catalytic thermal treatment, a

very satisfactory yield of gasoline is obtained. Usually in such a, case, depending, of course, upon the type of charging oil and the conditions of D- eration, the formation of carbonaceous substances flux condensate with said light reflux condensate and subjecting the mixture to non-catalytic thermal treatment, and supplying the vaporous reaction products from said non-catalytic thermal treatment to the fractionation step.

In a more specific embodiment the invention comprises fractionating catalytic conversion products, together with vaporous reaction products from the thermal treatment, to separate fractionated vapors, light reflux condensate having an end boiling point not substantally in excess v of 650 F. and heavy reflux condensate containing the fractions of the insufficiently converted hydrocarbons boiling above 650 F., commingling heavy reflux condensate with the charging oil in approximately a 1:1 volume ratio and passing the contents of this Vmixture in contact with a mass of cracking catalyst, commingling the remaining portion of said heavy reflux condensate in the catalytic treatment is relatively high. We

have found, on the other hand, that if instead of returning all of the heavy insuniciently converted hydrocarbons to the catalytic conversion step only a portion thereof is returned and the remaining portion, together with the light insuiciently converted hydrocarbons, is subjected to thermal treatment under conditions of temperature and pressure selected to favor 'reactions which tend to convert undesirable carbon forming constituents into heavier hydrocarbons,v that the formation of carbonaceous substances during catalytic cracking is reduced accordingly. Preferably also, conditions are employed in the thermal treatment which favor the reaction mentioned above rather than conversion to gasoline.. although some of the latter may also appear.

In one embodiment the invention comprises passing vapors of a hydrocarbon oil at a cracking temperature in contact `with 'a mass of cracking catalyst, fractionating the' catalytic conversion products to separate fractionated vapors boiling substantially in the range of gasoline, light reflux condensate, and a heavier reflux condensate, supplying a portion of the ,last named reflux condensate to the catalytic conversion step, commingling the remaining portion of the heavy rewith said light reflux condensate and subjecting the mixture to no n-catalytic thermal treatment, and separating non-vaporous liquid residue from the vaporous reaction products formed in said thermal treatment.

The various cooperative features of the present invention may be further understood from a description of a process flow, and for this purpose the attached drawing has been provided which shows diagrammatically by the aid of conventional gures in general side elevation an arrangement of interconnected units in which the process may be conducted.

Referring to the drawing, charging oil comprising, for example, naphtha, kerosene, light and heavy gas oil or, when desired, any mixture thereof is supplied through line I containing valve 2 to pump 3. Pump 3 discharges through line containing valve 5 after which the oil is com mingled with heavy reflux condensate separated in the manner to be described and the mixture introduced to heating coil 6 which receives heat from furnace l. When desired, steam and/or light gaseous hydrocarbons, the latter comprising either those formed in the process or light gases introduced from anexterior source, maybe commingled with the mixture of hydrocarbon oilin line 4 to aid in substantially completely vaporiz'- ing the hydrocarbon oil supplied to heating coil 6 and also as a means for reducing the totalpressure on the hydrocarbon oil. In any event, the mixture supplied to heating coil 5 is substantially completely vaporized therein and heated to a temperature ranging, for example, from 800 to 1200 F. preferably while being maintained under a pressure ranging, for example, from substanwherein the catalyst is containedvin a plurality of elongated tubular elements of relatively small diameter and wherein provisions are made for passin-g some suitable heat convective medium `such as combustion gases in contact with the exterior of said elongated tubular elements whereby to supply heat to the reactants during reactivation of the mass of catalytic material. Reactor Il), on the other hand, may comprise a cylindrical vessel which is well insulated to reduce radiation losses and which contains one or a plurality of beds of catalytic material wherein the reaction may be accomplished substantially adiabatically.

In the catalytic cracking of hydrocarbons relatively large amounts of carbonaceous substances are formed which deposit upon the catalytic material thereby reducing its active surface and necessitating reactivation at periodic frequent intervals. The invention contemplates reactivating the used catalytic material in the usual manner, such as, for example, by passing oxygencontaining reactivating gases in contact with the used catalyticjmaterial and removing` carbonaceous substances as combustion gases along with the -spent reactivating gases. It is desirable, therefore, in order that the operation may -be carried out as a continuous process to employ at least two reactors and in some instances more than two reactors so that while the catalytic material in one or more reactors is being used for eifecting conversion of the hydrocarbon reactants the catalytic material in the other or others may be undergoing reactivation.A

Catalysts which have been found to be eiective in the catalytic cracking of hydrocarbon vapors may comprise pellets or granules of silica or other siliceous and refractory materials composited with compounds selected from the group consisting of alumina, zirconia, and thoria. ln addition, the hydrosilicates of alumina, acid treated clays, or the like, have also been found to be effective in the cracking treatment of hydrocarbon vapors. Although the catalysts above recited are generally considered to be the preferredJ catalysts their use is not to be construed as a limiting feature, for various other catalysts well known to those in the art may be employed within the broad scope of the invention.

The conversion products are removed from reactor I by way of line I| and may be directed through'valve |2 into line I8 by means of which they are introduced to fractionator 20. Preferably, however, the conversion products in line are directed through line I3 containing valve I4 into Vaporizing and separating chamber I5 wherein they commingle with reaction products formed in the non-catalytic thermal treatment in the manner to be described. Vaporizing and -separating chamber I5, together with the fractionator and condensing, and .collecting equipment in communication therewith, may be oper- I per square inch. Non-vaporous liquid residue is separated from the vaporous products in chamber I5 and the non-vaporous liquid residue removed therefrom by way of line |6 containing valve I'l, recovered as a product of the process or subjected to any desired further treatment.

Vaporous products separated in chamber I5 are directed through line I8 containing valve I9 into fractionator 20. As above mentioned, when the catalytic conversion products are not introduced to chamber I5, the same may be commingled with the vaporous products in line I8 in the manner previously described. v Vaporous products in fractionator 20 are fractionated therein to separate fractionated vapors boiling substantially in the range of gasoline from the higher boiling insufficiently converted hydrocarbons and the latter condensed in the ractionator as reflux condensate.

Fractionated vapors separated in fractionator 20 are conducted through line 2| containing valve 22 to cooling and condensation in condenser 23. Distillate, together with undissolved and uncondensedv gases from Acondenser 23, is directed through line 24 containing valve 25v into receiver 2B wherein the distillate and gases are collected and separated. Undissolved and uncondensed gases collected and separated in receiver 26 are removed therefrom by way of line 21 containing valve 28 and a portion may be utilized in the catalytic conversion treatment as above mentioned or 'the whole or any portion thereof recovered as a product of the process. A portion of the distillate collected and separated in receiver 26 may be returned to the upper portion of fractionator 20 by well known means, not shown, as a relluxing andcooling medium while the remaining portion thereof is removed from receiver 26 by Way of line 29 containing valve 30, recovered as a product of the process or sub jected to any desiredfurther treatment.

Reflux condensate condensed in fractionator 20 is preferably further separated into light reflux condensate having an end boiling point not substantially in excess of 650 F, and a heavy reflux condensate containing the insufficiently converted hydrocarbons boiling above said light reflux condensate. Heavy reflux condensate separated in fractionator 20 is removed therefrom by way of line 3| and a portion directed through line 32 containing valve 33 into line 38 where it commingles with the light reflux condensate for treatment in the manner to be described. The remaining portion of the heavy reflux condensate in line 3| is directed through valve 34 to pump 35 which discharges through line 36 containing valve 31 into line 4 where the heavy reflux condensate commingles with the charging oil for treatment in the manner previously described. The amount of heavy reflux condensate supplied to the catalytic conversion step preferably does not exceed the volume of fresh charging oil, although in some'instances depending upon the particular charging oil and the conditions of operation, a greater amount may be supplied.

Light reflux condensate separated in fracvalvev 39, commingled with the heavy reflux condensate introduced by way of line 32.in the manner previously described, and the mixture supplied to pump 40. PumpA 40' discharges through line 4| containing valve 42 into heatingA coi143 which receives heat from furnace 44. A mixture of light and heavy reflux condensate supplied t0 coil 43 is heated thereinoa temperature ranging, for example, from 800 to l000 F., or there-` abouts, while being maintained under a superatmospheric pressure ranging, for example, from 100 to 1000 pounds or more per square inch. Temperatures and pressures are chosen for the treatment in coil 43 which favor reactions which tend to convert the undesirable carbon forming constituents present in the reux condensate into heavier hydrocarbons which are removed as liquid residue from vaporizing and separating chamber l5. i

'Ihe heated products leaving coil 43 are directed through line 45 containing valve 46 into kreaction chamber 41 wherein conversion reactions instigated in the -heating coil proceed to the proper degree of completion. Reaction Vchamber 41, in the case here illustrated, is`

preferably operated under a superatmospheric pressure substantially the same or slightly less than that employed in the communicating heating coil and preferably also is insulated to reduce radiation losses therefrom, although no insulation appears in the drawing. Reaction products leaving chamber 41 are directed through line 48 containing valve 49 into chamber I5 wherein they are subjected to treatment in the manner previously described. When desired, the use of reaction chamber 41 may be obviated by providing sui`n`cient soaking time in coil 43 and introducing the reaction products from coil 43 to chamber l 5, and since the means for accomplishing this are Well known, such means are not illustrated.

An example of one specific operation of the process as it may be accomplished in an apparatus such as illustrated and above described is as follows:

, Charging oil comprising a 33 A. P. I. gravity l Mid-Continent gas oil is commingled with approximately an equal volume of heavy reflux condensate separated in the manner to be described. 'Ihe mixture is heated and vaporized at a temperature of 960 F. and under a lsuperatmospheric pressure of 30 pounds per square inch. The heated vapors are passed in contact with a mass of silica-alumina-zirconia catalyst at a liquid hourly space velocity of 2.v t

The catalytic conversion products-are commingled with reaction products formed in a subsequent non-catalytic thermal step and the mixture supplied to a vaporzing and separating chamber operated at a superatmospheric pressure of 20 pounds per square inch. In the vaporizing .and separating chamber non-vaporous liquid residue is separated from the vaporous products and the former recovered therefrom as a product of the process. The vaporous products separated as above mentioned are fractionated to separate fractionated vapors of approximately 400 F. end point from the higher boiling in sufficiently converted hydrocarbons. Fractionated vapors are subjected to cooling and condensation and the resulting distillate and gas collected andV separated. The heavier insufciently converted hydrocarbons separated in'the fractionator are condensed as light and heavy reflux condensate, the light reflux condensate having an end boiling point of approximately 525 F. while the heavy reflux condensate contains the hydrocarbons boiling above 525 F. A portion of the heavy -reflux condensate is supplied to the catalytic conversionstep in the manner previously described.

The -remaining portion of the heavy reux condensate separated as above mentioned is commingled With the light reilux condensate and the mixture subjected to thermal treatment in a heating coil and communicating reaction chamber at a temperature of 960 F. and at a superatmospheric pressure of 300 pounds per square inch. The reaction products leaving the reaction chamber are supplied to the vaporizing and separating chamber for treatment in the manner previously described.

From an operation employing conditions as above described one may obtain approximately '71.5% of 400 F. end point gasoline of 75.5 octane rating, approximately 13.3% of 6 A. P. I. gravity residuum, the balance being carbon, gas, and loss.

We claim as our invention:

1. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydrocarbon oil at a cracking temperature in contact with a mass of cracking catalyst, fractionating the resulting catalytic conversion products to separate fractionated vapors, light reflux ccndensate, and heavier reflux condensate, dividing said heavier refiux condensate into portions of like composition, supplying one of said portions to the catalytic conversion step, commingling another of said portions with said light reux condensate and subjecting the mixture to noncatalytic thermal conversion treatment, and supplying vaporous reaction products from said noncatalytic thermal treatment to the fractionation step.

2. A process for the conversion of hydrocarbon oil which comprises heating and vaporizing said hydrocarbon oil and passing the heated vapors lytic conversion step, commingling` another of said portions with said light reflux condensate and ysubjecting the mixture to non-catalytic thermal conversion treatment,' and supplying vaporous reaction products from said non-catalyticthermal treatment to the fractionating step.

3. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydrocarbon oil at a cracking temperature in contact with a mass of cracking catalyst, supplying the resulting catalytic conversion products to a vaporizing and separating zone and therein separating liquid residue from cracked vapors, fractionating said cracked vapors to separate fractionated vapors, light reflux condensate, and a heavier reux condensate, dividing said heavier` reflux condensate into portions of like composition, supplying one of said portions to the catalytic conversion step, commingling another of said portions with said light reflux condensate yand subjecting the mixture to non-catalytic thermal treatment, and supplying reaction products from said non-catalytic thermal treatment to said vaporizing and separating step.

4. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydrocarbon oil at a cracking temperature in contact with a mass of cracking catalyst, fractionating the resulting catalytic conversion products to separate fractionated vapors, light reflux condensate, and heavier reflux condensate, dividing said heavier reux condensate into portions of like composition, supplying one of said portions to the catalytic 4conversion step, commingling,

another of said portions with said light reflux condensate and subjecting the mixture to noncatalytic thermal treatment in a heating coil and communicating reaction chamber, and supplying vaporous reactions products from the non-catalytic thermal treatment to the fractionation step.

5. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydrol carbon oil` at a cracking temperature in contact with a'mass of cracking catalyst, fractionating the resulting catalytic conversion products to separate fractionated vapors, light reux condensate having an end boiling' point not substantially in excess of 650 F., and a heavier redux condensate containing hydrocarbons boiling above Athose in said light refiux condensate, dividing said heavier reflux condensate into portions of like composition, supplying one of said portions to the catalytic conversion step, commingling another of said portions with said light reflux condensate and subjecting the mixture to noncatalytic thermal conversion treatment, and supplying v aporous reaction products from said noncatalytic thermal treatment to the fractionation step.

6. A process forthe conversion of hydrocarbon `oil which comprises passing vapors of said hydrocarbon oil at a cracking temperature in contact with a mass ofsilica-alumina-zirconia catalyst,

fractionating the resulting catalytic conversion ,from said non-catalytic thermal treatment to the fractionation step.

ROLAND .BJ DAY. ELMER R. KANHOFER.

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