US2010369A - Conversion of hydrocarbon oils - Google Patents

Description

Aug. 6, 1935. J. c. MORRELL 2,010,369

CONVERSIQN 0F HYDROCARBON OILS Filed Aug. 51, 1932 FRACTIONATOR FURNACE 7 49 RECEIVER INVENTOR JACQUE C. MORRELL ATTORNE Patented Aug. 6, 1935 UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Jacque C. Morrell, Chicago, Ill., assignor to Unlversal Oil Products C ompany, Chicago, 111., a

corporation of Delaware Application August 31, 1932, Serial No. 631,174

This invention 4 Claims.

particularly refers to an improved process and apparatus for the conversion of relatively light oil while simultaneously subjecting a heavier oil to milder conversion conditions in the same cracking provides for the separation verted intermedia system and further of insufficiently conte products of the cracking operation into relatively light and relatively heavy fractions, subjecting said light fractions to further conversion together with the light charging stock and subjecting said heavy fractions to further conversion together with the heavy charging stock.

The light oil treated may or naphtha for the antiknock value.

comprise a gasoline purpose of improving their The great flexibility of the process resides in supplying heat to the relatively heavy fractions being charged by the relatively highly heated lighter fracti susceptible to heating at hi ons which are more gh temperatures for relatively long periods without excessive cracking; A specific embodiment of the present invention may comprise subjecting a hydrocarbon oil to conversion temperature at super-atmospheric pressure in a heating coil,

simultaneously subjecting another hydrocarbon oil of higher boiling characteristics to a mil perature by commingling it heated lighter oil from the ducing the hot commingled der conversion temwith the stream of heating coil, introlight and heavy oils into an enlarged reaction chamber maintained at super-atmospheric pressure wherein vaporous and residual liquid conversion products quickly separate and wherein the vapors are subjected to continued conversion, withdrawing residual liquid from the reaction chamber to a zonegof reduced pressure wherein its controlled further vaporization is effected, assisted, when desired. by the introduction thereto of all or a portion of the vaporous products se parately withdrawn from said reaction chamber, subjecting the vapors, including those resulting from conversion and those resulting tion of the residue porizing chamber,

from said further vaporizain the reduced pressure vato fractionation whereby their insufiiciently converted components are condensed as reflux condensate arated by fractionation in fractions, subjecting the nents of the vapors, which and arbitrarily septo light and heavy lower boiling comporemain uncondensed by fractionation, to condensation and collecting v the resulting products, returning the heavy fractions of said reflux condensate to further conversion, together with the heavy charging stock,

and returning the light fra ctions of said reflux condensate to further conversion in the heating coil together with the light charging stock.

For the sake of convenience, the light and heavy charging stocks will be hereinafter referred to respectively as primary charging stock and 5 secondary charging stock. The secondary or heavy charging stock preferably comprises an oil of relatively high initial boiling point or of wide boiling range such as crude oil or topped crude, gas oil, fuel oil, residual oil or the like, or mixtures thereof, while the primary or light charging stock preferably comprises an oil of lower initial boiling point or narrower boiling range such as light gas oil or other distillate, gasoline, naphtha, kerosene, pressure distillate bottoms or the like, or mixtures thereof.

Vaporization of the residual liquid-in the reduced pressure vaporizing chamber is controlled, in part, by the degree of pressure reduction between the reaction chamber and the vaporizing 2o chamber'as well as the temperature at which the residual oil is withdrawn from the reaction chamher and introduced into the vaporizing chamber and may be further controlled by the introduction of all or any desired portion of the hot vaporous products from the reaction chamber into the vaporizing chamber. The vapors may be withdrawn from the reaction chamber together with the residual liquid andthe commingled materials introduced into the vaporizing chamber or the vapors may be separately withdrawn from the reaction chamber and separately introduced into the vaporizing chamber, in the latter case, entering this zone preferably below the level of residual oil so that intimate contact is established between the vapors and the residual liquid in the vaporizing chamber.

The light or low boiling fractions of the reflux condensate returned to further conversion, together with the primary charging stock, may vary in boiling point characteristics, depending, in part, upon the nature of the primary charging stock as well as upon the operating conditions employed in the process and the desired characteristics'of the final light distillate product of the system. This material may, for example, have an initial boiling point of 400 to 437 F., or thereabouts, when the antiknock value of the total ,lower boiling products is sufllciently high or when it is desired to separately return said lower boiling products to further treatment, as will be later more fully described. However, when some of the heavy'ends of the product of motor fuel boiling range are of poor antiknock value they may be included in the light fractions of the light distillate product of the system may be returned to further treatment in a heating coil together with the light or primary charging stock and the low boiling fractions of the reflux condensate, in which case the distillate is preferably subjected to conversion conditions which will materially improve its antiknock value without excessively altering its boiling range.

\ The quantity and quality of the primary charging stock and low boiling fractions of the reflux condensate and the conditions to which they are subjected in the heating coil are so controlled that they will contain an adequate supply of heat for transmission to the secondary charging stock and high boiling components of the reflux condensate with which they are commingled to raise the heavy oils to the desired conversion. temperature at the pressure maintained in the reaction chamber. In this manner the light oils are themselves converted and also serve as a heat carrying medium comprising the sole, source of heat for the heavier oils. By this method of heating the heavy oils and by quickly removing residual liquid conversion products from the reaction chamber, excessive conversion and the consequent formation of substantial quantities of coke and high yields of gas is avoided while the vaporous products from both the light and heavy oils are subjected to continued conversion in the reaction chamber for a predetermined time, which prac- ..tice is conducive to the production of low boiling distillates of high antiknock value.

The accompanying diagrammatic drawing illustrates one specific form of apparatus in which the features of the present invention are .incorporated and tin which the process of the invention may be (practiced.

Referring to the drawing, primary or light .charging stock maybe supplied through line I and valve 2 to pump 3 from which it is fedthrough line 4 and valve 5 to heating'coil 6 wherein it is subjected to the desired conversion temperature by means of heat supplied from a furnace 1.01 any suitable form. The highly heated oil is discharged from heating element 6 throu line 8 and valve 9 into reaction chamber 10. It will be understood that the oil may be preheated in any well known manner, when so desired, prior to its introduction into the heating coil, although preheating means are not shown in the drawing. Simultaneous with the introduction of heated oil from heatingelement 6 into reaction chamber ii), a secondary charging stock, of higher boiling characteristics than the primary charging stock, is supplied through line I I and valve I! to pump l3 from which it may be fed through line I4 and valve l5 into the line 8, commingling therein with the stream of heated oil from heating coil igbeing thereby heated to a milder conversion temperature than that employed in heating coil 6 and passing thence into reaction chamber l0 wherein it is subjected to conversi n.

-When desired, a portion or all of the secondary or heavy charging stock may be 'diverted from line through line I6 and valve I1 into fractionator, 18 wherein it comes into direct contact with the hot vaporous products undergoing fractionatiomassistingtheir fractionation and being 2,910,869 of the reflux condensate which, in this case, may

thereby preheated. The preheated secondary charging stock collects, together withthe high boiling fractions of the reflux condensate formed' in fractionator i8 and said heavy fractions of the reflux condensate or heavy reflux condensate and preheated raw oil, as the case may be, is withdrawn fromthe lower portion of the fractionator through line i9 and valve 20 to pump 2! from which this material is fed through line 22, valve 23 and line H into line 8 and thence to reaction chamber l0 together with the stream of heated oil from. heating coil 6. The secondary charging stock or secondary charging stock and heavy reflux condensate may, when desired, be preheated in. any other well known manner, not illustrated in the drawing, to below conversion temperature, priorto being commingled with the heated oil from heating coil 6.

As already mentioned, the quality and quantity of the oil supplied to heating coil 6 and the conversion conditions to which it is subjected inthe heating coil is sufficient to heat the secondary charging stock and low boiling components of the reflux condensate from fractionator l0 which are commingled therewith to the desired conversion temperature under the pressure conditions employed in reaction chamber l0, which preferably employs a substantial superatmos-v version temperature. Preferably, however, both streams of oils enter the lower portion of the reaction chamber wherein the residual liquid conversion products quickly separate from the lighter vaporous conversion products, the latter being subjected to continued conversion as they pass upward through the reaction chamber while the residual oil is quickly removed from the lower portion of the reaction zone through line -32" and valve 33jto a reduced pressure vaporizing chamber 34. However, the conversion products may, when desired, enter the upper portion of chamber ID by well known means, not shown in the drawing, being subjected to continued conversion as the outlet from they pass downward through'this zone and being withdrawn in commingled state-through line 32 and valve 33 to chamber 34. When vaporous and residual liquid conversion products are separated in chamber III, as first described, the vapors may be withdrawn from the upper portion of the chamber through line 35' or may pass, all or in part,

Chamber 34 is preferably operated at substantially reduced pressure relative to that employed in the reaction chamber and by regulating the degree of pressure reduction in this zone the temperature of the products introduced thereto from chamber ill and the manner of their introduction, further vaporization of the residual oil maybe controlled so that a residual liquid product of 34. The residual oil remaining unvaporized in chamber 34, may be withdrawn therefrom to cool-' ing and storage or to any desired further treatment through line 39 and'valve 40. Vapors are removed from chamber 34 through line 4| and valve 42 and pass through line 35 to fractionation in fractionator l8, together with any vapors supplied direct to fractionator l8 from chamber 10, as already described.

The insufliciently converted components of the vapors supplied to fractionator l8 are condensed therein as reflux condensate and arbitrarily separated into low boiling and high boiling components. The high boiling components of the reflux condensate are withdrawn from the lower portion of the fractionator and returned to further conversion together with the secondary charging stock,.as already described. The low boiling components of the reflux condensate are withdrawn from the upper portionof fractionator l8 through one or a plurality of lines 43 controlled by valves '44 and pass through line 45 to pump 46 from which they are returned through line 41, valve 48 and line 49 to.heating coil 8 for further conversion together with the primary charging stock.

Vaporous products of the desired end-boiling point are withdrawn from the upper portion of fractionator l0 through line 50 and valve 5|, and are subjected to condensation and cooling in condenser 52 from which the resulting distillate and uncondensable gas passes through line 53 and valve 54 to collection in receiver 55. Uncondensable gas maybe released from receiver 55 through line 55 and va1ve'51. Distillate may be withdrawn from the receiver through line 58 and valve 59'. A portion of the distillate collecting in receiver 55 may, when desired, be withdrawn through line 60 and valve 6| to pump 62 from which it is returned through line 49 and valve 63 to heating coil 6, together with the low boiling components of the reflux condensate and the secondary charging stock to be subjected in this zone, preferably to conversion conditions which will improve the antiknock value of 'the recycled distillate. By the use of this feature of the invention which permits dilution of the primary charging stock and light fractions of reflux condensate with a portion of the light distillate product of the system, higher conversion temperatures may be employed in heating coil 6 than "would otherwise be satisfactory and this high conversion temperature and increased quantity of heated oil from heating coil 6 are often found useful in furnishing the required heat to the secondary charging stock and heavy fractions of the reflux condensate.

The maximum conversion temperature to which the primary or light charging stock and light fractions of the reflux condensate are subjected in the heating coil may range, for example from 925 to 1050 F. with a super-atmospheric pressure measured at the outlet from the heating coil ranging from 100 to 800 pounds, or more, per square inch. A super-atmospheric pressure substantially equalized with that at the outlet from I the heating coil or'somewhat reduced, may be employed in the reaction chamber and by' commingling the secondary charging stock and heavy fractions of the reflux condensate with the heated products from the heating coil, a reduced temperature ranging, for example, from 850 to 950 F., may be obtained in the reaction chamber. The vaporizing chamber is preferably operated at a substantially reduced pressure relative to -that employed in the reaction chamber, said reduced pressure ranging, for example, from 100 pounds, or thereabouts, per square inch, down to substantially atmospheric pressureand substantially this same range of pressures may be employed in the succeeding fractionating, condensing and collecting portions of the system.

As a specific example of the operation of the process of the present invention, the primary charging stock which comprises about two-thirds by volume of the total raw oil charged to. the system is a 45 A. P. I. gravity Pennsylvania naphtha which is subjected in the heating coil to a temperature of about 970 F., at a super-atmospheric pressure of about 400 pounds per square inch. The remaining one-third or secondary portion of the total charging stock is a 22 A. P. I. gravity mid-continent fuel oil which, together with high boiling fractions of the reflux condensate, is commingled with the stream of heated oil from the heating coil, prior to its introduction into the reaction chamber. The reaction chamber is main- 400 pounds per square inch and the vaporizing chamber is operated at a reduced super-atmospheric pressure of about 50 pounds per square inch, which is substantially equalized in the succeeding fractionating, condensing and collecting portions of the system. The overhead product from the fractionator, which is condensed as the motor fuel product of the system, has an endbeiling point of about 400 F., and the low boiling fractions of the refluxcondensate returned to the heating coil for further conversion, together with the primary-charging stock, have a boiling range of approximately 100-to 600 F. The heavier reflux may be returned together with the heavier charging stock and thus minimize the chances of coking the tube if not to prevent coking altogether.

This operation may yield about '72 percent of motor fuel having an antiknock value equivalent to an octane number of approximately 14, the additional productsof the system being about per cent of marketable fuel oil and about 600 ctubilg feet of gas, per barrel of total charging s cc By returning a portion of the distillate to the heating coil, in an operation such as above described, its antiknock value may be materially increased at the expense of a somewhat lower yield .of motor fuel and a corresponding increase in the yield of gas.

Other combinations of charging stocks of various types such as gasolines, kerosenes, etc., with heavy oils such as California, Mexican and Venezuelan residues have been cracked with remarkably good yields of gasoline of high antiknock quality and long operating periods.

I claim as my invention:

1. A process for the conversion of hydrocarbon oil which comprises subjecting raw oil charging stock of low boiling characteristics to conversion temperature at super-atmospheric pressure in a heating coil and communicating enlarged reaction chamber, simultaneously subjecting another hydrocarbon oil charging stock of higher boiling characteristics to a milder conversion temperature in the reaction chamber by introducing reaction chamber, separately withdrawing them therefrom, introducing vapors separately withdrawn from the reaction chamber into direct contact with the unvaporized residual oil in the reduced pressure vaporizing chamber, whereby to assist its further vaporization, subjecting vaporous products resulting from both the cracking operation and said further vaporization of the residue to fractionation, subjecting the light components of the vapors which remain uncondensed by fractionation to condensation, collecting the resulting distillate and gas, separating the heavier components of, the vapors which are condensed by fractionation into low boiling and high boiling fractions, returning the low boiling fractions to the heating boil for further conversion and subjecting the high boiling fractions to further conversion, together with saidhydrocarbon oil charging stock of higher boiling characteristics.

2. A process of the character defined in claim 1 wherein a portion of the distillate, resulting from condensation of the vapors remaining uncondensed by fractionation, is subjected to further.

conversion in the heating coil, together with the low boiling fractions of the vapors condensed by fractionation and the hydrocarbon oil charging stock of low boiling characteristics.

3. A hydrocarbon oil cracking process which comprises heating a relatively light oil to cracking temperature under pressure while flowing in a restricted stream through a heating zone and thence discharging the same into an enlarged reaction zone, simultaneously subjecting a heavier oil to milder conversion temperature in the reaction zone by eommingling the same with the heated oil from the heating zone, separating the commingled oils into vapors and unvaporized oil in the reaction zone, quickly removing unvaporized oil from the reaction zone and introducing the same in a vaporizing zone maintained under lower pressure than the reaction zone,

4. A hydrocarbon oil cracking process which comprises heating a relatively light oil containing a substantial quantity of hydrocarbons within the gasoline range to cracking temperature under pressure while flowing in a restricted stream through a heating zone and thence discharging the same into an enlarged reaction zone, simultaneously subjecting a heavier oil to milder conversion temperature in the reaction zone by commingling the same with the heated oil from the heating zone, separating the commingled oils into vapors and unvaporized oil in the reaction zone, quickly removing unvaporized oil from the reaction zone and introducing the same in a vaporizing zone maintained under lower pressure than the reaction zone, subjecting the vapors to continued conversion in the reaction zone, separately withdrawing such further converted vapors from the reaction zone and commingling the same with the flashed vapors evolved in the vaporizing zone, subjecting the commingled vapors to common fractionation and separating therefrom relatively light and heavy reflux condensate, returning the light reflux condensate to the heating zone and supplying the heavy reflux condensate to the reaction zone together with said heavier oil, and finally condensing the fractionated vapors.

JACQUE C. MORRELL.

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