US2122777A - Hydrocarbon oil conversion - Google Patents

Description

J. C. MORRELL HYDROCARBON OIL CONVERSION Jul 5, 1938.

Filed Aug. 25, 1930 2 Sheets-Sheet l I Illllll W r WW 0 m M c 2 Sheets-Sheet 2 cfac as C Nor/"e17 July 5, 1938. J. c. MORRELL HYDROCARBON OIL CONVERSION Filed Aug. 25, 1930 Patented July 5, 1938 UNITED STATES HYDROCARBON Jacque C. Morrell, Chicago, 111., assignor, by mesne assignments, to Universal Oil Products Company, Chicago, 111., a corporation of Dela- Ware Application 7 Claims.

This invention relates to the conversion or cracking of higher boiling hydrocarbon oils for the production of lower boiling hydrocarbon oils. It relates more specifically to the simultaneous topping and cracking of crude oils. 7

In one of its embodiments, the invention relates to a treatmentof crude oil wherein the oil is subjected to a topping or mild cracking operation, the heavier portions resulting therefrom being subjected to a cracking treatment, with the production of light hydrocarbon vapors and heavy unvaporized residue, the vapors being suitably fractionated. In this embodiment of the invention, the vapors from the topping treatment may be utilized in assisting the fractional condensation of the vapors which are evolved during the cracking operation. The invention also contemplates the utilization of the heavier portions from the topping step in a control of the dephlegmation or fractionation of the vapors arising from the cracking operation, and if the unvaporized residue from the cracking operation is subjected to a flash distillation, the heavier portions from the topping operation may likewise be used to control conditions of flashing of said residue.

The invention further contemplates in one of its iorms, subjecting reflux condensate from the various dephlegmating and fractionating zones of the flashing system to vapor phase cracking, the products therefrom, if desired, being utilized to a certain extent to control the distillation in the flashing zone of the cracking system.

The products from the vapor phase cracking treatment may assist in a control of the fractionation of the lighter hydrocarbons generated in the cracking operation and may control the character of the distillate which is obtained.

Many other features of the invention will become evident from a study of the following description of the drawings, which are diagrammatic and not drawn to scale, and of the process of the invention which isv capable of being carried out by the apparatus illustrated in the drawings.

Raw oil charging stock for the process may be introduced through line i and valve 2 to pump 3 which feeds the oil either through line .4, valve 5, line 5 and Valve 1, directly into the heating element 3 or from pump 3 the oil may pass through line 9 and valve Ill to heat exchanger H where it is preheated by indirect contact with hot vapors, as will be more fully described later, and thence passes, in its preheated state, through line I2, pump [3, valve l4 and line [5 into line 4 from where it may pass August 25,

Renewed April 5, 1937 PATENT OFFHCE OIL CONVERSION 1930, Serial No. 477,531

with that portion, if any, of the raw oil fed directly through line 4 from pump 3 to heating element 8 as above described. Pump i3 is necessary only when the pressure carried on heat exchanger H is less than the pressure employed in heating element 8 and may otherwise be eliminated.

When the charging stock to the process is an oil containing some light constituents such as gasoline the temperature attained by the charging stock in passing through heat exchanger Il may be sufficient to vaporize a portion of these light constituents which, in this case, are removed as vapors through line it and valve H, are subjected to condensation and cooling in condenser l8 thereafter passing through valve l9 and line 20 into receiver 2| from which uncondensed gas may be removed through line 22 controlled by valve 23 and from which the condensed distillate may be removed through line 24 controlled by valve 25.

Heating element 8 is located in a suitable furnace setting 26 and, in the specific form of apparatus herein illustrated, furnace 26 also accommodates another heating coil 44 which will be described later. Heating element 8 is preferably so situated within the furnace that the oil passing therethrough is subjected to milder heating conditions than those employed in heating element 44. These relatively mild conditions may be only sufiicient to eiiect the subsequent vaporization of the light portions of the charging stock or they may be sufiicient to mildly crack the oil passing therethrough.

From heating element 8 the oil may pass through line 21 and valve '28 into chamber 29. If conversion temperatures are employed in heating element 8, chamber29 may serve as a reaction chamber but if milder temperatures are employed chamber 29 may be used only asa vaporizing and separating chamber.

The unvaporized oil may be removed from chamber 29 through line 30 and when it is of such character that desirable products may be Pump 39 may return 7 Conditions imposed upon the oil in heating eleportion of the oil from pump 39 is preferably diverted from line 40 through line 42 and valve 43 and thus fed through heating element 44. The unvaporized products from chamber 29 may, instead of passing overhead to dephlegmator 36, be directed from pump 33 through line I23 and valve I24 directly into line 40 there mixing with reflux condensate from dephlegmator 35 and flowing therewith to heating element 8 or heating element 44 or in part to both as already described.

44 is the heating'element above referred to which is located together with heating element 8 in furnace 26 and is preferably so situated that more severe heating conditions may be employed in heating element than in heating element 8.

ment 44 are in all cases sufficient to cause its substantial conversion and may range from '750 to 1200 F., more or less, with pressures ranging from subatmospheric to superatmospheric pres-.

sures of say.2000 lbs. per sq. in., more or less.

It is to be understood that the construction here shown is only one of the many forms which may be employed and heating elements 8 and 44 may, if desired, be located in separate furnaces with conditions on each independently controlled.

If desired a portion of the charging stock from line 4 may be passed through line 45 and valve 46 and mixed in line 42 with the oil fed to heating element 44.

Products from heating element 44 may pass through line 4'! and valve 48 into reaction chamber 49 from which vapors may be withdrawn through line 50 and valve 5| to dephlegmator 35.

Here the vapors are subjected to fractionation, their heavy, insufliciently converted portions being returned for reconversionthrough line 31 as above described. Vapors from the top of dephlegmator 36 may pass through line 52 and valve .53 to fractionating tower 54. Here the cracked vapors may be. subjected to further fractionation alone 'or in combination with vapors from ehamber 29 introduced to fractionator 54 though line 55, valves 56 and 51 and line 58.

Vapors from the top of fractionator 54 may be removed. through line 6i and valves 52 and 63,

may be subjected to condensation and cooling in condenser 54 thereafter passing through valve and line 65 into receiver vt! from which uncondensed gas maybe removed through line 68 controlled by valve 69 and distillate may be removed through line I9 controlled by valve II;

If it is desired to separately fractiona'te the vapors from chamber 29 they may be passed through valve'59 and line 60 into fractionating tower I2. Vapors from the top of fractionator I2 removed through line I3 may be combined in line 6| with the vapors from fractionator 54 by passing-through valve 14 and line I5 or they may be separately condensed, cooled and collected by passing through valve 16 in line I3 into condenser 1'! and thence through valve I8 and line' into receiver 8!. Uncondensed gas may be with drawn from receiver BI through line 82 controlled by valve 83 andthe condensed distillate may beremoved from receiver through line 84 controlled by valve 85.

Portions of the condensed distillate from receiver 8! and from receiver 61, either or both maybe returned by'well known means, not shown, to any or all of the fractionating towers 36, 54 and 72 to assist fractionation and or" the vapors therein.

cooling line and valve 9| into reaction chamber 92 may be diverted from line 88 through valves I28 and 93, line 94 and pump 95 to heating element 96 or any portion may be withdrawn from the system through valve 9'! and'line 98.

Likewise reflux condensate from fractionating tower 72 may be withdrawn through line 59 and valve I08, may be directed all or in part through the same lines and valves utilized for the reflux condensate from tower to any or in part to all of the same elements to which reflux condensate from'tower 54 is directed or any portion of this reflux condensate from tower '52 may be removed from the system through line It)! controlled by valve I02.

It will be'understood that reflux condensate from tower 54 and reflux condensate from tower 72 may combine in, any proportion in line 38 and the combined product may be directed in part through any or all of the paths through which the individual streams of reflux condensate may flow as above described.

Heating element 95 is located in a suitable V through heating element 95 are preferably more severe than the conditions in heating element 8 or in heating element 44 and preferably approximate what is commonly termed vapor-phase or high temperature cracking, for example, temperatures from 925 to 1200 F., more or less, at pressures ranging from subatmospheric to superatmospheric pressures of 2000 lbs. per sq. in., more or less.

Products from heating element 95 may be dis charged through line I04, valve I05 and valve I06 into reaction chamber 92. There may be several of these chambers in parallel arrangement for alternate operation to provide for coke storage and removal. If desired the heated products from heating element 96, before passing into chamber 92, may be directed through drum I01 by opening valves I08 and I 09 and closing valve IE5, or if desired the heated products may be diverted from chamber. 92 and may pass from drum I01 through line I23 and valves IE9 and I24 to line 55 and thence into either tower I2 through valve 59 or,into tower 54 through valve 51 or in part to both' towers.

Drum I01 serves as a zone in which 'heavy pitch-' residual products from reaction chambers 49 and 29 which products may be withdrawn from the respective chambers through line II2 controlled by valve H3 and through line 30 controlled by It is to be understood in this connection that residual products from both reaction chambers The distillation may even be carried to coke owing-to theincreased temperature resulting from residue from chamber 92.

the introduction of vapors from heating element 96, or the residual product from either chamber alone may be directed all orin part to chamber 92 for flash distillation, the remaining residual products, if any, from chambers 49 and 29 being separately withdrawn from the system by well known-means not shown.

In the ordinary cracking process in which a flash distilling system for residue is employed the pressure upon residual products is preferably reduced'in the flash chamber to such an extent that the latent heat made available by this pressure reduction will serve to vaporize the lighter portions of the residual products. In this process this pressure reduction may be accomplished by the regulation of valve H9 in line H5 but in many cases will not be necessary as the tempera- ,ture of the products introduced into chamber 92 from heating element 99 may be sufficient to further vaporize the residual products in this same zone to the desired degree without reducing the pressure in chamber 92 below that employed in ;chamber 29' or in chamber 49 or in heating element 96, whichever employs the lowest pressure. It may even be desirableto cool the material in chamber 92to prevent its reduction to coke and/ or to regulate the quality of the unvaporized material if it is desired to withdraw a liquid This cooling will be effected by introducing reflux condensate from fractionating tower 54 or from fractionating tower I2 or from both through line 99 and valve 9I into the liquid in chamber 92.

Non-vaporized liquid products from chamber 92 maybe withdrawn through line I I! controlled by valve II8. Vapors from chamber 92 may pass through line I I9, valve I29, heat exchanger I I, line I2l, valve I22 into line 55 and thence through "valve 51 in line 59 or through valve 59 in line 60 or in part through both to either or both of the fractionating towers 54 and I2. portion or all of the vapors from chamber 92 may by-pass heat exchanger II through line I25 and "'valve I26.

v out the system or the various parts of the system.

The temperature of the products from heating element 8, from heating element 44 and from heating element 95 may range from 450 to 1200 more or less, however heating element 8 preferably employs either temperatures below those which produce conversion or relatively mild conversion temperatures while heating element 44 h preferably employs somewhat higher conversion, conditions and heating element 96 employs still "more severe conversion conditions.

employed in the system may vary on different. elements and may range from subatmosphericpressures to say 2000 lbs. per sq. in., more or less. Pressure may be substantially equalized throughmay be operated at differential pressures. #Preferably, however, that part of the system comprising heating element 44, reaction chamber 49,

dephlegmator 39 and their interconnecting lines If desired any.

Pressures employs the highest pressure utilized in the system while heating element 8, reaction chamber 29 and fractionating tower 54 preferably employ a reduced pressure and heating element 96, chamber 92, heat exchanger I I and fractionating tower i2 may utilize a still further reduction in pressure. Differential pressures are often desirable, however, between the various elements in any or all of the three main pressure divisions of the process above mentioned and, in most cases, fractionating towers 54 and I2, if both towers are used, will be operated at substantially equalized pressure.

It will be apparent to those skilled in the art that, if desired, the residual oil introduced into chamber 92 for flash distillation may be reduced to substantially dry coke. This mode of operation may be carried out in a number of ways, for instance, the heated products introduced to chamber 92 from heating element 96 may be at a higher temperature than when liquid residuum is produced or the temperature of the residual oil itself withdrawn from reaction chamber 49 may be increased by maintaining a higher temperature at the outlet from heating element 44, or, if reduced pressure is normally employed in reaction chamber 49 when residuum type operation is employed, additional heat may be left stored within the residual oil in this zone by maintaining it under a higher pressure prior to its introduction into chamber 92. On the other hand, the pressure in chamber 92 may be reduced below that normally employed in residuum type operation and this chamber may even, if desired, be operated under partial vacuum if cooling is employed in reaction chamber 92 by the introduction of reflux condensate from fractionation.

As a specific example of one of the many types of operation which may be employed in the embodiment of my process such as above described, a A. P. I. gravity Mid-Continent crude oil containing approximately 20% of natural gasoline forms. the raw oil charging stock to the system. Approximately 15% of straight-run gasoline is removed in heat exchanger II and collected in receiver 2|. I

The remaining 85% of topped crude is then fed to heating element 8 where it is subjected to mild cracking at an outlet temperature of approxi-, mately 825 F. and a pressure of approximately 135 lbs. per sq. in. The products from heating element 8 enter chamber 29 at a reduced pressure of approximately 60 lbs. per sq. in. and evolved vapors are subjected to fractionation in tower 54 at substantially the same pressure.

The unvaporized liquid from chamber 29 is reprocessed, together with reflux condensate from dephlegmator and a portion of the reflux condensate from fractionating tower 54, in heating element 4 where it is subjected to an outlet temperature of approximately 910 F. A

pressure of approximately 200 lbs. per sq. in. is employed in heating element 44, chamber 49 and dephlegmator 36.

but the vapors therefrom are reduced to a pres-,

sure of approximately 60 lbs. per sq. in. before entering heat exchanger I I and tower I2 in which the cracked vapors from heat exchanger II are fractionated. Reflux condensate from tower I2 directed to'chamber 92 where a direct heatexchange between this relatively cool residual produ'ct' and the relatively hot-'reconverted vapors from heating element 96 serves to vaporize desirable portions of the residual product at the same time condensing undesirable or heavy products from-the reconverted vapors. The unvaporized residualmaterial from chamber 92 is removed therefrom as the final residual product from the system. However, without cooling means the material in chamber 92 may be vaporized to coke.

'In an operation such as above outlined the yields of various products from the system based on the crude oil charged may be somewhat as follows: Approximately 15% of natural or straight-run gasoline may be collected in receiver 21; approinmately 40% of liquidvapor-phase cracked gasoline may be produced and collected in receiver 8|; approximately 15% of vaporphase cracked gasoline having a high anti-knock rating may be produced and collected in receiver 61. The gas and coke produced by the entire system may, in this case, amount to some 18% of the total charge and the final heavy residual product from the system may amount to some 12% of the total charge.

By" reducing to coke in the chamber 92 the totalgasoline yield in the example shown will be increasedto and the coke and gas to 25%.

Diversion of a larger proportion of reflux from dephlegmator 36 to the high temperature heating coil "decreases gasoline production somewhat and increases the gas. The anti-knock value of the gasoline" is however improved. Increasing the temperature in heating element 96 has: the same efiect.

What I clai'm as: my invention is:

1. A process for the conversion of heavy hydrocarbon oils which comprises subjecting charging oil in a heating zone to cracking temperatures, reacting the oil so treated in a reaction zone to form vapors and unvaporized residue, withdrawing the vapors and. subjecting them to partial condensation in a dephlegmating zone to form vapors and reflux condensate, the vapors from the dephlegmating zone being subjected to fractionation in a fractionating zone to separate the lighter from the heavier components thereof, unvaporized residue from the reaction zone being withdrawn to a zone of reduced pressure wherein it is distilled by virtue of its contained heat, cold charging oil being subjected to a topping step outside said reaction zone and separated into lighter components in the form of vapors and heavier components in the form of liquid, passing vapors from the zone of reduced pressure and from the topping step directly to the'fractionating zone, liquid from the topping stepl, being introduced in part into the zone of reduced pressure to assist in controlling distillation therein, and in part into the dephlegmating zone to assist in the partial condensation of the vapors from the reaction zone. 7

2. A process for the conversion of heavy hydrocarbon oils which comprises subjecting charging oil in a heating zone to cracking temperatures, then reacting it in a'reaction zone to produce vapors and unvaporized residue, the vapors being withdrawn and subjected to fractionation in a fractionating zone, the unvaporized residue being subjected to distillation in a zone of reduced pressure by virtue of its contained heat, cold charging oil being subjected to a topping step to separate the lighter portions in the form of vapors from the heavier portions in the form of liquid, vapors from the: zone of reduced pressure and from the topping step being introduced into the fractionating zone to assistin the fractionation of the vapors therein, reflux condensate from the fractionation zone being subjected to vapor phase cracking, a portion of the products of said cracking being returned tothe zone of reduced pressure to assist in distillation therein, liquid from the topping step: being likewise introduced into the zone of reduced pressure, a portion of the liquid from the topping step being introduced into the heating zone for conversion.

3.. A process for the conversion of heavy hydrocarbon oils which comprises subjecting charging oil in a heating zone tocracking temperatures, reacting the oil so treated in a reaction zone to produce vapors and unvaporized residue, the'vapors being withdrawn and subjected to partial condensation in a dephlegmating zone, the dephlegmated vapors being subjected to further fractionation in a fractionating zone to separate the lighter components in the form of vapors from the heavier components in the form of reflux condensate, the reflux condensate being subjected to vapor phase cracking, the products of the vapor phase cracking being introduced in part into the fractionating zone to control the character of the product obtained, unvaporized residue from the reaction zone being distilled in a zone of reduced pressure to obtain further vapors and unvaporized residue, the vapors being in troducedinto the fractionating zone to assist in' controlling the fractionation therein, charging oil being subjected to a topping step to separate the lighter portions in the form of vapors from the heavier portions in the form of liquid, the vapors from the topping step being utilized to assist in the-fractionation of the vapors undergoing treatment in the fracionating zone,'the liquid from the topping step being introduced in part with the charging oil into the heating zone for conversion therein and in part into the dephlegmating zone;

to assist in the partial condensation of the vapors therein. V I

4. A process for the conversion ofheavy hying oil in a'heating zone to cracking temperadrocarbon oils'whichcomprises subjecting chargtures, reacting the oil so treated in a reaction zone to produce vapors and unvaporized residue, the vapors being withdrawn and subjected to partial condensation in a dephlegmating' zone the dephlegmated vapors being subjected to fractionation in a fractionating zone to separate the lighter components in the form of vapors from the heavier components in the form of reflux condensate, the reflux condensate being subjected to Y vapor phase cracking, the products of the vapor phase cracking being introduced in part into the fractionating zone to control the character of the product obtained, unvaporized residue from the reaction zone being distilled in a zone of reduced pressure to obtain further vapors and unvaporized residue, the vapors being introduced into the fractionating zone to assist in controlling the fractionation therein,'charging oil being subjected to a topping step to separate the lighter portions in the form of vapors from the heavier portions in'the form of liquid, the Vapors from the topping step being utilized to assist in the fractionation of the vapors undergoing treatment in the fractionating zone, the liquid from the topping step being introduced in part with the charging oil into-the heating zone forconversion therein, in part into the d-ephlegmating zone to assist in the partial condensation of the vapors therein, and in part into the zone of reduced pressure to assist in controlling distillation therein.

5. A conversion process which comprises cracking hydrocarbon oil in a pressure cracking zone under sufiicient pressure to maintain a substantial portion thereof in liquid phase, simultaneously topping crude oil in an independent zone and combining resultant vapors with vapors produced by said cracking, fractionating the combined vapors and subjecting reflux condensate thus formed to vapor phase cracking conditions in a second cracking zone, removing unvaporized oil from said pressure zone and from said independent zone and introducing the same to a coking zone, discharging the heated products from the second cracking zone into the coking zone to assist distillation of the unvaporized oils therein, supplying vapors from the coking zone to the fractionating step, and finally condensing the fractionated vapors.

6. A conversion process which comprises subjecting hydrocarbon oil to cracking conditions of temperature and superatmospheric pressure in a heating zone and communicating enlarged zone, separately removing vapors and unvaporized oil from the enlarged zone, simultaneously'partially distilling charging oil for the process in a second enlarged zone, introducing unvaporized oil withdrawn from the first-named enlarged zone and unvaporized charging oil from the second enlarged zone into a third enlarged zone maintained under lower pressure than the first named enlarged zone and further distilling these oils in the third enlarged zone, fractionating the vapors evolved in said enlarged zones to condense heavier fractions thereof as reflux condensate, supplying a portion of the reflux condensate to said heating zone and subjecting another portion thereof to vapor phase cracking conditions in a second heating zone, introducing resultant vapor phase cracked products into said third zone to assist the distillation of the unvaporized oils therein, and finally condensing the fractionated vapors.

7. A conversion process which comprises subjecting hydrocarbon oil to cracking conditions of temperature and superatmospheric pressure in a heating zone and communicating enlarged zone, separately removing vapors and unvaporized oil from the enlarged zone, simultaneously partially distilling charging oil for the process in a second enlarged zone, introducing unvaporized oil withdrawn from the enlarged zone and unvaporized charging oil from the second enlarged zone into a third enlarged zone maintained under lower pressure than the enlarged zone and further distilling these oils in the third enlarged zone, combining vapors evolved in the second and third chambers with vapors withdrawn from the enlarged zone and fractionating the resultant mixture to condense heavier fractions thereof as reflux condensate, supplying a portion of the reflux condensate to said heating zone and subjecting another portion thereof to vapor phase cracking conditions in a second heating zone, discharging the heated products from the second heating zone into said third enlarged zone to assist the distillation of the unvaporized oils therein, and finally condensing the fractionated vapors.

JACQUE C. MORRELL.

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