US2006552A - Conversion of hydrocarbon oils - Google Patents

Description

July 2, 1935. J. B. HEID CONVERSION OF HYDROCARBON OILS Filed Dec. 11, 1931 FRACTIONATOR FURNACE 7,

INVENTOR JACOB BENJAMIN HEID BY 0%W ATT Patented July 2, 1935 CONVERSION OF HYDROCARBON OILS Jacob Benjamin Heid, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111.,

a. corporation of South Dakota Application December 11 ,-1931, Serial No; 580,352

g 2 Claims. (01. 196-49) This invention relates to the conversion of hydrocarbon oils and more particularly refers to the conversion of relatively heavy oils or oils of inferior quality for the production of substan- 5 tial yields of desirable light products such as motor fuel of high antiknock value.

The primary principles of the present invention-comprise subjecting a hydrocarbon oil to relatively mild conversion conditions and thence subjecting the total liquid and vapcrous products of such' relatively mild conversion to further treatment under more severe" conversion conditions. I

'The relatively mild conversion conditions to which the charging stock supplied-to the system is first'subiected are preferably of a nature such as will effect the production of from'lo to so percent, or thereabouts, based on the charging stock, of materials of substantially 'rnotor fuel boiling 90 range. The percentage of such material produced by the initial conversion will, of course, vary with different charging stocks and different conversion conditions, but the extent of conversion of the charging stock in this initial stage of the process is held within the limits which preclude any substantial formation of coke or carbonaceous material or any other heavy residual products which would form extensive quantities of coke or carbonaceous materialin the heating element of 30 the succeeding conversion range. The features of the invention thus permit the production, from a wide variety of charging stocks, under initial conversion conditions in the system,jof a select charging stock suitable for conversion in, the succeeding conversion stages of the system to produce substantial yields of desirable light products such as motor fuel of high antiknock value;

It should be noted that this method diifers from other cracking systems wherein select charging stocks are produced for further conversion in at least two important respects; namely, by the method of the present invention the raw'oil charging stock is subjected in the primary stages of the system to conversion rather than to distillation without conversion, and furthermore all of the products resulting from said initial conversion are collectively subjectedtofurther con version without'removal of any of their components.

A more specific embodiment of the present invention may comprise subjecting the hydrocarbon oil to relatively mild conversion conditions in a heating element, introducing the heated materials into an enlargedreaction chamber where conversion, particularly of the vapors, may continue and wherefrom liquid conversion products a may be withdrawn without extensive further conversion in this zone, maintaining both the heating element and the reaction chamber under substantial superatmospheric pressure, simultaneously withdrawing both liquid and vaporous'prodnote from said reaction chamber and subjecting them to further conversion in a separate heating element preferably under more severe conversion conditions than those employed in the first mentioned heating element, introducing heated materials from said separate heating element into a separate enlarged reaction chamber wherein continued conversion, particularly of the vapors, is effected, maintaining said separate heating element and said separate reaction chamber at substantial superatrnospheric pressures, introducing both liquid and vaporous products from said separate reaction chamber to a reduced pressure vaporizing chamber where further vaporization of the residual liquid and its separation from the vapors is effected, subjecting vaporsfrom' said vaporizing zone to fractionation whereby their relatively heavy component s are condensed, returning said relatively heavy components either to said separate heating element for further conversion or to said first mentioned reaction chamber, or in part to both, subjecting vapors and gas from the fractionator to condensation-and cooling, and collecting the resulting distillate and gas, l v

The attached diagrammatic drawing illustrates one specific form of apparatus embodying the principles and features of the presentinvention; raw oil charging stochfor the system may be supplied through line i and valve '2 into pump 3, from which'it is fed through line 4 and valve 5 to heating element 6, to be subjected therein to relatively mild conversion conditions by means of heat supplied from a furnace l of any suitable form. The heated oil is discharged from heating element 6 through line 3 and valve 9 into reaction chamber iii, which, like heating element 6, is preferably maintained at substantial superatmospheric pressure. Both liquid and vaporous products are Withdrawn from chamber I0 through line H and valve l2 to pump l3, by means of which they are fed through line M, valve l5 and line it to be subjected to further conversion in heating element 11. I

Heating element ll is located in a furnace l8 of any suitable form capable of supplying the required heat to the oil undergoing conversion and'heated materials are discharged from heat-' ing element Il'through line l9 and'valve 20 to reaction chamber 2L- Chamber 2! and heating.

element ll are both preferably maintained a substantial superatmospheric, pressure: Both liquid and vaporous products'are withdrawn from chamber 2| through line .22 and Valve 23 and are introduced, into vaporizing chamber 24, which is preferably maintained at a substantially reduced pressure relative to that employed in chamber 2|. Further vaporization and cooling of the residual oil from chamber 2| and its separation from the vapors is effected in chamber 24. Residual liquid remaining unvaporized in chamber 24 may be withdrawn through line 25 and valve 26 to cooling and storage or to any desired further treatment. Vapors from chamber 24 pass through line 21 and valve 28 to fractionation in fractionator 29.

The relatively heavy components of the vapors which have not been sufiiciently converted are condensed in fractionator 29, collecting in the lower portion of this zone to be withdrawn therefrom through line 30 and valve 3| to pump 32. Pump 32 supplies the reflux condensate from fractionator 29 either through line 16 and valve 33 direct to heating element IT or, if desired, all or a portion of said reflux condensate may be diverted from line [6 through line 34 and valve 35 into reaction chamber Ill, commingling there in with the conversion products in this zone and passing therewith through line H, valve l2, pump l3, line I4, valve l5 and line I6 to further conversion in heating element I'I. When all or a portion of the reflux condensate from fractionator 29 is supplied, as described, to chamber In it may serve as a means of diluting and cooling the other conversion products withdrawn from chamber II], but in any case is eventually subjected to further conversion in heating element l1.

Vapors from fractionator 29, comprising the desired distillate products of the system and uncondensable gas, pass through line 36 and valve 31 to be subjected to condensation and cooling in condenser 38, distillate and uncondensable gas from which pass through line 39 and valve 40 to be collected in receiver 4|. Uncondensable gas may be released from the receiver through line 42 and valve 43. Distillate may be withdrawn from this zone through line 44 and valve 45. If desired, a portion of the distillate from receiver 4| may be recirculated, by well known means not illustrated in the drawing, to the upper portion of fractionator 29 to assist fractionation of the vapors in this zone and to maintain the desired vapor outlet temperature.

Pressures employed within the system may range from atmospheric to superatmospheric pressures as high as 2000 lbs. or more per square inch. Conversion temperatures employed may range from 750 to 1200 F., more or less. Preferably the primary conversion stage of the system employs relatively mild conversion conditions with temperatures at the outlet from the heating element ranging, for example, from 750 to 850 F., and pressures in both'the heating element and the reaction chamber, which may range from 100 to 500 lbs., or more, per square inch and which may be either substantially equalized between these two zones or may be somewhat reduced in the reaction chamber. In the secondary conversion stage of the system the preferred range of temperature in the heating element is from 850 to 950 F., or thereabouts, with pressures ranging from 100 to 500 lbs. or thereabouts, per square inch in both the heating element and reaction chamber. Preferably the vaporizing chamber and the succeeding fractionating, condensing and collecting portions of the system utilize substantially reduced pressures of the order of substantially atmospheric to 100 lbs. or thereabouts per square inch.

As a specific example of the operation of the process of the present invention a 36 A. P. I. gravity Pennsylvania gas oil is the raw oil charging stock to be treated. It is subjected in the primary heating element of the system to a temperature of approximately 820 F. A superatmospheric pressure of approximately 250 lbs. per square inch is employed in both the heating element and reaction chamber of this portion of the system. A portion of the reflux condensate from the fractionator of the system is introduced into the reaction chamber of the primary conversion stage, the remainder being fed together with the total products withdrawn from said reaction chamber to the heating element of the secondary conversion stage. A temperature of approximately 910 F. is employed in the secondary heating element and a substantially equalized pressure of approximately 350 lbs. per square inch is employed in this heating element and the succeeding reaction chamber. duced pressure of approximately 35 lbs. per square inch is employed in the vaporizing, fractionating, condensing and collecting portions of the system. This operation may result in the production of approximately '72 percent of motor fuel having an antiknock value approximately equivalent to a blend of 80 percent iso-octane and 20 percent normal heptane. In addition, about 16 percent of residual oil is produced, the remaining products of the system being principally uncondensable gas and a relatively small amount of carbonaceous material.

I claim as my invention:

1. A process for producing high antiknock motor fuel from heavy hydrocarbon oils com prising initially heating the oil to a comparatively mild cracking temperature in a heating coil, thence delivering the same to the upper end of a vertically elongated reaction chamber wherein substantial vaporization occurs, withdrawing both liquid oil and vapors from the bottom of said vertically elongated chamber, effecting the removal of the liquid at such a rate that no accumulation of a liquid body in the reaction chamber occurs, passing the liquid and vapors withdrawn from the elongated reaction chamber together with reflux condensate formed as hereinafter set forth through a second heating coil where the conditions are such as to further crack the liquid oil and vapors, increasing the antiknock character of the gasoline components thereof and cracking the reflux condensate, introducing the heated constituents from said second coil to a second vertically elongated reaction chamber and withdrawing all products from the bottom thereof without permitting accumulation of any appreciable body of liquid in said secondary reaction chamber and efiecting further distillation of the products under reduced pressure, separating the vapors from residue and dephlegmating the same to condense heavier fractions thereof, adding such condensed fractions to said liquid and vapors as said reflux condensate, and finally condensing the dephlegmated vapors.

2. The process as defined in claim 1 further characterized in that said reflux condensate is added to said liquid and vapors by being introduced to the first-mentioned vertically elongated chamber.

JACOB BENJAMIN HEID.

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