US2105549A - Conversion of hydrocarbon oils - Google Patents

Description

Jan. 1a, 1938. MORRELL 2,105,549

CONVERSION OF HYDROCARBON OILS Filed Dec. 20, 1934 SEPARATOR FURNACE RECEIVER DISTILLING AND FRACTIONATING COLUMN FURNACE 56 INVENTOR JACQUE C. MORRELL TTOBNEY Patented Jan. 18, 1938 UNITED STATES PATENT OFFICE versal Oil Products Company, Chicago, 111.,

a corporation of Delaware Application December 20, 1934, Serial No. 758,443

7 Claims.

This invention particularly refers to an improved process for the treatment of hydrocarbon oils of relatively wide boiling range embodying the cooperative steps of topping, cracking,

coking and reforming.

In one specific embodiment, the invention comprises subjecting charging stock for the process, comprising an oil of relatively wide boiling range, such as crude petroleum, for example, to

1;) fractional distillation whereby it is separated into relatively low-boiling and high-boiling fractions, subjecting said low-boiling fractions of the charging stock, including its components within the boiling range of motor fuel as well as, when I; desired, somewhat higher boiling fractions such as naphtha, kerosene or kerosene distillate and the like, to conversion or reforming in a heating coil, partially cooling the resulting products by indirect heat exchange with hydrocarbon oil charging stock for the process, whereby to retard or arrest their conversion, heat the charging stock for the purpose of effecting or assisting said fractional distillation thereof and remove heavy polymers and residual liquids from the vaporous conversion products, subjecting the vaporous conversion products to fractionation whereby their insufliciently converted components are condensed as reflux condensate and separated into selected relatively low-boiling and high-boil- 39 ing fractions, subjecting fractionated vapors of the desired end-boiling point to condensation, recovering and separating the resulting distillate and gas, subjecting high-boiling fractions of said reflux condensate to conversion conditions of elevated temperature and superatmospheric pressure in a separate heating coil, introducing the resulting heatedproducts into a coking chamber wherein the residual liquid conversion products are reduced to substantially dry coke, subjectin'g low-boiling fractions of said reflux condensate toindependently controlled conversion conditions of elevated temperature and superatmospheric pressure in another separate-heating coil, introducing the resulting highly heated products into said coking chamber, withdrawing the vaporous products from the coking chamber and separating therefrom tars and similar high cokeforming materials, returning the latter to the coking chamber and subjecting the remaining vaporous products from the coking operation to further conversion in the first mentioned heating coil together with said low-boiling fractions of the charging stock. The high-boiling fractions of the charging stock may be supplied direct to 35 the coking chamber or subjected to conversion tgether with the high-boiling fractions of the reflux condensate or, when desired, both the highboiling fractions of the reflux condensate and the high-boiling fractions of the charging stock may be supplied direct to the coking chamber without 5 passing through said separate heating coil.

It will be apparent from the foregoing as well as from the following further description of the process of the present invention that its various features and the various stages of the process are 10 interdependent and mutually contribute to produce the desired final results.

The accompanying diagrammatic drawing illustrates one specific form ofapparatus in which the process of the invention may be accom- 15 plished.

Referring to the drawing, hydrocarbon on charging stock preferably comprising, as already mentioned, an oil of relatively wide boiling range such as crude petroleum or the like, preferably containing a substantial proportion of both relatively low-boiling and relatively high-boiling fractions, is supplied through line I and valve 2 to pump3 by means of which it is fed through lines 4' and 5 and valve 6 into heat exchanger 1 wherein it is subjected to indirect heat exchange with hot conversion products of the process and thereby heated to a temperature suflicient to effect its substantial vaporization and fractional distillation. The heated charging stock is discharged from the heat exchanger through line '8 and valve 9 into distilling and fractionating column Ill. The charging stock may, of course, be subjected to heating in any well known manner, not illustrated, instead of or in conjunction with the heating accomplished in heat exchanger Distilling and fractionating column In may be operated at any desired pressure ranging from substantially atmospheric to a high superatmospheric pressure of the order of several hundred pounds per square inch but preferably a superatmospheric prc ssure is employed in this zone sufficient to permit the passage of the overhead vaporous products from column 10 to and through heating coil 2| without the aid of a vapor pump or compressor. The charging stock is separated by fractional distillation in column l0 into selected relatively low-boiling and high-boiling fractions. The latter are collected as bottoms in the lower portion of column l0 from which they are withdrawn through line H and valve ii! to pump l3, by means of which they are fed through line l4 and may be directed through line l5, valve l6 and line 43 to conversion in heating coil 4 5, or this material may be directed through valve H in line [4 through lines T0, 58 and 41 into coking chamber 49. The selective low-boiling fractions of the charging stock arewithdrawn as vapors may be subjected to condensation and the I resulting distillate supplied-by means of a suitable pump to heating coil 2!, although these alternative methods of operation are not illustrated in the drawing.

Heating coil 2| is located within a furnace 22 of any suitable form by means of which the oil passing through the heating coil is subjected to the desired relatively high conversion temperature at any desired pressure. The hot conversion products are discharged from heating coil 2! though line 23 and valve 24 into heat exchanger I wherein they are cooled sufficiently,

by indirect contact with charging stock for the process, supplied to this zone as previously described, to prevent any appreciable further conversion thereof. Partial cooling of the conversion products in heat exchanger 7 serves to remove therefrom by condensation undesirable heavy liquid components such as heavy polymers, residual liquid and the like which may be withdrawn from the 'heat exchanger and directed through lines 25 and H and Valve 26 to column 10 wherein they commingle with the high-boiling fractions of the charging stock and are directed therewith to further treatment as will be later more fully described. As an alternative method of operation the condensate from heat exchanger 1 may, when desired, be directed through valve 18 in line 25 to pump 19 by means of which it is supplied through line 80, valve\8l and line 58 to coking chamber 49. The vaporous conversion products remaining uncondensed in heat exchanger 1 are directed therefrom through line 21 and valve 28 to fractionation in fractionator 29.

The components of the vaporous conversion products supplied to fractionator 29 boiling above the range of the desired final light distillate product of the process are condensed in this zone as reflux condensate and the reflux condensate is separated by fractional distillation into selected relatively low-boiling and high-boiling fractions which are subjected to selective conversion, a will be later more fully described.

Fractionated vapors of the desired end-boiling point are withdrawn, together with uncondensable gas produced within the system, from the upper portion of fractionator 29 through line 30 and valve 3| and are subjected to condensation and cooling in condenser 32. The resulting distillate and gas passes through line 33 and valve 34 to collection and separation in receiver 35. Uncondensable gas may be released from the receiver through line 36 and valve 31. Distillate may be withdrawn from receiver 35 through line 38 and valve 39 to storage or to any desired further treatment. A regulated portion of the distillate collected in receiver 35 may, when desired, b'e recirculated by well-known means,-not

fractionator 29 to serve as a cooling and refluxing medium in this zone for assisting fractionation of the vapors and to maintain the desired vapor outlet temperature from the frac-.

tionator.

'The high-boiling fractions of the reflux condensate formed in fractionator 29 are withdrawn from the lower portion of this zone through line 40 and valve 4| to pump 42, by means of which they are fed through line 43 and valve 44 and may be directed through valve 14 and supplied, either alone or together withthe high-boiling oils from the lower portion of column l0, \which may be directed into line 43 in the manner previously described, to conversion in heating coil' able form and the stream of hot conversion products is discharged from the heating coil through line 4] and valve 48 into coking chamber 49. Heating coil 45 may, of course, be eliminated, when desired, by supplying both the bottoms from distilling and fractionating column l9 and the high-boiling fractions of the reflux condensate from fractionator 29 direct to coking chamber 49 in the manner previously described, in which case the heat required to effect conversion and coking of these relatively high-boiling oils in coking chamber 49 is derived from the highly heated conversion products supplied to this zone from heating coil 55, as will be later more fully described.

Selected relatively low-boiling fractions of the reflux condensate formed in fractionator 29 may be withdrawn from any suitable intermediate point or plurality of points in this zone and, in

the case here illustrated, this material is directed through line and valve 5| to pump 52 by means of which it is fed through line 53 and valve 54' to conversion in heating coil 55, where'- in it is heatedto the desired conversion temperature, preferably at a substantial superatmospheric pressure, by means of heat supplied from a furnace 56 of any suitable form. The stream of hot conversion'products is-discharged from heating coil 55 through line 51 and may be directed through line 58, valve 59 and line 41 into coking chamber 49, together with the stream of hot conversion products from heating coil 45, or the conversion products from heating coil 55 may be separately introduced into the coking chamber at any desired point or plurality of points in this zone. Provision is shown in the drawing for directing all or a portion of the hot conversion products from heating coil 55 through valve 60 in line 51 into the lower portion of the coking chamber, wherein they commingle with and serve to supply additional heat to the materials undergoing coking in this zone.

Coking chamber 49 may be operated at any desired pressure ranging from substantially atmospheric to several hundred pounds per square inch superatmospheric and preferablya superatmospheric pressure is employed in this zone sufficient to permit the passage of vapors products therefrom through heating coil 2i without the use of a vapor pump or compressor. The liquid components of the conversion products supplied tothe coking chamber are subjected to fur:- ther distillation and/or conversion in the zone and the resulting residue is reduced to substantially dry coke. The coke may be allowed to accumulate within the coking chamber until it is substantially filled, following which the chamber may be isolated from the rest of the system, cleaned and prepared for further operation. When desired, a plurality of coking chambers may be employed, although only one is illustrated in the drawing, in which case they preferably are alternately operated, cleaned and prepared for further operation 'so that the duration of the operating cycle of the process is not limited by the capacity of the coking zone. Chamber 49 is provided with a suitable drain-line 6| controlled by valve 62 which may also serve as a means of introducing steam, water or any other suitable cooling medium'into the chamber, after its operation is completed and after it has been isolated from the rest of the system, in order to hasten cooling and facilitate the removal of coke from the chamber.

Vaporous products are withdrawn from the upper portion of the coking chamber through line 63 and valve 64 to separator .65, wherein any heavy components or entrained liquid particles such as tars and similar heavy liquids of a high coke-forming nature are removed from the vapors. When desired, in order to assist the removal of said high-boiling materials from the vaporous products from the coking zone, a regulated portion of the charging stock may be directed from pump 3 through valve 66 in line 4 into separator 65 and, when desired, regulated portions of either the low-boiling or high-boiling fractions of the reflux condensate formed in fractionator 29 may be supplied, by Well known means, not shown in the drawing, to separator 65 for the same purpose. The high coke-forming liq.- uids separated from the vaporous products from the coking chamber in separator 65 are withdrawn from the lower portion thereof through line 61 and valve 68 to pump 69 by means of which they are returned through means of line I0, valve H, line 58 and line 41 to coking cham: ber 49 for further treatment and reduction to coke.

The vaporous products from the coking chamber escaping condensation in separator 65 are directed therefrom through line 'l2 valve 13 and line 20 to further conversion in heating coil 2|,

as follows: When a heating coil is employed for conversion of the heavy oils, comprising the highboiling fractions of the charging stock or the high-boiling fractions of the reflux condensate or both, a conversion temperature ranging for example, from 800 to 950 F. may be employed at the outlet from this zone, preferably with a superatmospheric pressure at this point in the system of from 100 to 500 pounds, or more, per square inch. The heating coil to which the relatively low-boiling fractions of the reflux condensate are supplied may utilize an outlet conversion temperature ranging, for example, from 900 to 1000 F. preferably with a superatmospheric pressure, measured at the outlet from this zone, of from '200 to 800 pounds, or more, per square inch. The coking chamber may employ any desired pressure ranging from substantially the same as that employed at the outlet from the preceding heating coil employing the lowest pressure down to sub-v stantially atmospheric pressure, although a superatmospheric pressure at least slightly above the pressure employed in the succeeding heating coil is preferred in this zone= The distilling and fractionating column wherein the charging stock is subjected to fractional distillation may employ any desired pressure ranging from substantially atmospheric to 500 pounds, or more, per square inch, superatmospheric pressure and preferably a superatmospheric pressure is employed in this zone slightly higher than that employed in the succeeding heating coil. The heating coil to which low-boiling fractions of the charging stock and thevaporous products from the coking chamber are supplied may utilize an outlet conversion temperature ranging, for example, from 950 to 1100? F. with any desired pressure ranging from substantially atmospheric to 500 pounds, or more, per square inch, the higher temperatures normally being employed when lower pressures are utilized. The fractionating, condensing and collecting portions of the system may employ pressures substantially the same or lower than that employed at the outlet from the last mentioned heating coil.

As a specific example of the operation of the process of the present invention as it may be accomplished in an apparatus such as illustrated -and above described, the charging stock comprises a California crude of about 32.8 A. P. I. gravity containing approximately per cent of material boiling up to 200 F. and approximately 36 per cent at 437 F. and this material is subjected to fractional distillation by means of heat supplied thereto by indirect heat exchange with the hot conversion products from the heating coil to which the low-boiling fractions of the charging stock are supplied. The charging stock is separated by said fractional distillation into fractions boiling above and below approximately 550 F. The fractional distilling stage of the system is operated at a superatmospheric pressure of approximately 200 pounds per square inch. Approximately 50 per cent of the charging stock, comprising its fractions boiling above approximately 550 F. are subjected, together with highboiling reflux condensate from the fractionator of the cracking system, to a conversion temperature, measured atthe outlet from the separate heating coil to which these materials are supplied, of approximately 920 F. at a superatmospheric pressure of approximately 200 pounds per square inch which pressure is substantially equalized in the succeeding coking chamber. Selected lowboiling fractions of the reflux condensate, having a boiling range of approximately 400 to 600 F., are subjected to another separate heating coil to an outlet conversion temperature of approxi mately 970 F. at a superatmospheric pressure of approximately 400 pounds per square inch and the highly heated products from this heating coil are introduced into the coking chamber. Tars and similar high-boiling materials separated from the vaporous products from the coking chamber are returned to the coking chamber. The remaining vapors, together with the low-boiling fractions of the charging stock, are subjected in the heating coil to which they are, supplied to'an outlet conversion temperature, of approximately 1000 F. and the pressure utilized in this zone is substantially equalized with that in the distilling superatmospheric pressure of approximately 50 pounds per squarezinch. This operation may produce, per barrelfof charging stock, approximately 68 per cent of 400 F; end-point motor fuel having an octane number ofapproximately '75 by the motor method, the additional products of the process being approximately 50 pounds of relatively dry coke and the remainder uncondensable gas.

I claim as my invention:

1. A process which comprises topping crude petroleum, thereby forming topped crude and a distillate containing natural gasoline fractions of the crude, distilling the topped crude to coke in a coking zone, combining vapors from the coking zone with said distillate, heating the resultant mixture in a heating coil sufliciently to enhance the anti-knock value of said gasoline fractions,

fractionating resultant cracked vapors independently of said vapors from the coking zone and separating relatively heavy and light reflux condensates therefrom, supplying such heavier reflux condensate to the coking zone for reduction to coke together with the topped crude, subjecting the lighter reflux condensate to independently controlled cracking conditions of temperature and pressure in a second heating coil, and introducing resultant heated products into the coking zone to assist the coking of the topped crude and heavier reflux condensate therein. 7

2. The process as defined in claim 1 further characterized in that the topped crude and heavier reflux condensate, prior to introduction to the coking zone, are passed in admixture through a third heating coil and heated therein to a lower conversion temperature than is maintained in the first-named. and said second coils.

3. A process which comprises topping crude petroleum, thereby forming topped crude and a distillate containing natural gasoline fractions of the crude, distilling the topped crude to coke in a coking zone, separating relativelyheavy frac- (ions of the resultant vapors and returning the same to the coking operation, combining the remaining vapors from the coking zone with said distillate, heating the resultant mixture in a heating coil sufiiciently to enhance the anti-knock value of said gasoline fractions, fractionating resultant cracked vapors independenilyof said vapors from the coking zone and separating relatively heavy and light reflux condensates therefrom, supplying such heavier reflux condensate to the coking zone for reduction to coke together with the topped cr'ude, subjecting the lighter reflux condensate to independently controlled coking therein.

in a second heating coil, and introducingresultant heated products into the coking zone to assist the coking of the topped crude and heavier reflux condensate therein.

4. A process which comprises topping crude petroleum, thereby forming topped crude and a distillate containing natural gasoline fractions of the crude, distilling the topped crude to coke in a coking zone, combining vapors from the coking zone with said distillate, heating the resultant mixture in a heating coil suificiently to enhance the anti-knock value of said gasoline fractions, fractionating resultant cracked vapors independently of said vapors from the coking zone and separating relatively heavy and light reflux condensates therefrom, heating such heavier reflux 5. The process as defined in claim 1 further characterized in that said distillate is supplied to the first-named coil directly and without prior condensation from the topping operation.

6. A process for producing anti-knock motor fuel from crude petroleum containing straightrun gasoline, which comprises topping the crude in a topping zone to vaporize the gasoline therefrom, removing topped crude from said zone and distilling the same to coke in a'coking zone, combining vapors from the coking zonev with the gasoline-containing vapors from the topping zone,

; topped crude therein, and finally condensing the fractionated vapors.

7. A process for producing anti-knock motor fuel. from crude petroleum containing straightrun gasoline, which comprises topping the crude in a topping zone to vaporize the gasoline therefrom, removing topped crude from said zone and distilling the same to coke in a coking zone, combining vapors from the coking zone with the gasoline-containing vapors from the topping zone, heating the resultant vaporous mixture in a heat- .ing zone sufliciently to increase the anti-knock value of the gasoline contained therein, fractionating the resultant cracked vapors to separate relutively heavy and light reflux condensates therefrom, supplying such heavier reflux condensate to the coking zone for reduction to coke therein, subjecting the lighter reflux condensate to independently controlled cracking conditions of temperature and pressure in a second heating zone, discharging the heated products from said second heating zone into the coking zone to assist the coking of the topped crude therein, and finally condensing the-fractionated vapors.

JACQUE C. MORRELL.

crude undergoing

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