US2003536A - Cracking hydrocarbon oils - Google Patents

Description

J. B. HEID Filed Nov. 26, 1930 I FRACTIONATOR CONDE' SER 28f INVENTOR JACOB BENJAMIN HEID 04 4 ATTORNEY CRACKING HYDROCARBON OILS June 4, 1935.

REACTION CHAMBER 5 4 .9 l m .m n 2 l I) I I O o 0 m 2 2 L O 2 ijwhllwl H l w 3 l 1 I 2 2 2 |1H|IIIHNIHIIIIHIHHHHHHHHU a L W 5 B FURNACE I51 Patented June 4, 1935 UNITED STATES L PATENT OFFICE CRACKING HYDROCAEBON oms Application November 26, 1930, Serial No. 498,236

1 Claim.

This invention relates to improvements in the art of cracking hydrocarbon oils and refers more particularly to an improved process andiapparatus wherein relatively heavy hydrocarbon oils are converted into substantially lighter and more valuable products, with the resultant production of heavier liquid products, such as fuel oil and the like. I

Primarily, the invention comprises introducing a regulated proportion of cooling medium upon the surface of a body of residual liquid maintained within a chamber of an oil cracking process, where, due to the relatively high temperatures maintained therein, the cooling medium is vaporized, the vapor tension of the residual I liquid is increased, and a vaporization of the light components of the residual liquid is further assisted. At the same time, due to the vaporization of the cooling medium and the light components of the residual liquid, a substantial cooling of the remainder of the body of residual liquid is effected, preventing over-cracking and the formation of coke or heavy pitch-like or carbonaceous materials therein.

r The principles of the present invention may be applicable to any cracking process wherein a body of heated residual products are maintained in a confined zone under any'desired pressure condition, and may be especially advantageous when it is desired to effect further vaporization of the residual liquids while maintained under substantial superatmospheric pressures.

In the accompanying drawing, which is merely diagrammatic and illustrates one form of process in which the principles of the invention may be applied, raw oil charging stock may be supplied through a line.| controlled by valve 2 to a pump 3, and may be fed through a line 4 controlled by valve 5 to fractionator 6 for preheating by contact with the relatively hot vapors therein and further assist in their fractionation. The preheated raw oil, together with the heavier condensed portions of the vapors from fractionator 6 may thence pass through a line 1, trap 42, and line 8, the latter being controlled by a valve 4|, to a pump 9. Any desired portion or all of the raw oil may be diverted from fractionator 6 through a line In controlled by a valve to line 8 where it may combine with reflux condensate 50 issuing from fractionator 6, from whence it may pass to pump 9. Combined raw oil and reflux condensate may be supplied to heating element' I 4 through pump 9 and line |2 controlled by valve 3.

Heating element It may be located in any suitable form of furnace 5, and the oil passing therethrough may be heated to any desired conversion temperature and pressure, and may pass through line It controlled by valve into a reaction chamber |8. Heating element I4 and reaction 5 chamber 8 may be maintained under substantial superatmospheric pressure, or, if desired, reaction chamber |8 may be maintained under a substantially reduced pressure. Preferably, however, chamber |8 may be maintained under a sub- 10 stantial superatmospheric pressure to effect continued conversion of the products being passed therethrough. In ordinary cracking operations,

if the unvaporized residual liquid which may separate from the vaporized conversion products in 15 the reaction chamber is allowed to accumulate in this zone under the temperatures and pressures ordinarily prevailing therein, cracking will continue in the residual liquid as well as in the vapors, and, in fact, may be more pronounced in 20 the liquid, resulting in the excessive formation of coke or heavy, pitch-like or carbonaceous materials, as well as increasing the viscosity of said residual liquid, rendering it undesirable for use or sale as commercial fuel.

In order to control the cracking reaction, prevent excessive cracking, and, at the same time, eii'ect a substantial vaporization of the relatively light components of the residual liquid within chamber I8, I may introduce into said chamber 30 regulated quantities of a cooling medium, such as water in a relatively cold state, or relatively coldwater and oil through a line l9 controlled by a valve 20. The cooling medium is preferably introduced in such manner as to cause it to contact 35 directly with the surface of the hot residual liquid while said cooling medium is in its liquid state, bringing about its vaporization at substantially the point of contact on the surface of said residual liquid. In order to accomplish a liquid-uponliquid contact, I may provide a line 2| extending throughout chamber |8 from its upper limits to substantially the predetermined liquid level of the residual products within said chamber, as exemplifled by a line L-L in the drawing. If a variable liquid level be employed within said chamber, provision may be made for varying the length of the line 2| to such varying level, or, if desired,

a plurality of inlet lines l9 controlled by suitable valves 20' and provided with extensions 2| may be disposed within said chamber at various levels, and the cooling medium may be introduced through any of said inlets, dependent upon the level maintained in said chamber at any particular operation. Preferably, the cooling medium is not introduced at a point substantially below the surface of the liquid within chamber l8, since I have found that the best results are obtained by a contact of the cooling medium with the surface of the residual liquid.

To obviate the possibility of the cooling medium accumulating in the liquid state in the reaction zone, residual products may be continuously withdrawn from the lower limits of the chamber l8 through a line 22 controlled by a valve 23.

Vapors from chamber I8 may pass through line 24 and valve control 25 to fractionator 6 where their relatively heavy insufiiciently converted portions may be condensed and returned to the heating element M for reconversion, as already described, while the lighter portions of the-fractionated vapors may pass through a line 26 controlled by valve 2! and be subjected to condensation and cooling in condenser 28, the resultant products therefrom passing through a line 29 controlled by valve 30 to a receiver 3|. Distillate may be Withdrawn from receiver 3| through a line 32 controlled by valve 33. Incondensable gases may be released from receiver 3| through a line 34 controlled by valve 35. Any desired amount of the distillate from receiver 3| may be withdrawn through line 36 controlled by valve 31 for recirculation by means of pump 38, line 39 controlled by valve 40 to fractionator 6 where they may assist in the fractionation of the vapors within said fractionator.

To prevent any of the water which may be used as the cooling medium introduced into chamber l8, and which may pass into the fractionator 5 as steam, entering the heating element [4 with the reflux products from said fractionator, a trap 42 surrounding line 1, may be attached to the fractionator 6. Products passing into said trap 42 may be withdrawn therefrom through a line 43 controlled by valve 44.

Conversion temperatures employed may range from 750 to 1200 F., more or less, and the various zones of the cracking system may be operated under substantially equalized or differential pressures, ranging from sub-atmospheric to superatmospheric of about 2000 pounds or more per square inch.

As a specific example of one operation embodying my invention, a 32 A. P. I. gravity topped crude was subjected to a conversion temperature of approximately 900 F., with a substantially equalized pressure of about 200 pounds per square inch being maintained in the system. In this operation, no cooling was effected over the residual products within the reaction chamber, and a yield, based on the charge, of about 54% of motor fuel was obtained, having an anti-knock value of about 35% benzol equivalent. In addition, about 12% of pressure distillate bottoms and about 26% heavy residual oil, relatively high in suspended carbon and B. S. content, unsuitable without retreatment for sale as commercial fuel oil was produced, together with a remaining 8% of gas and coke loss.

In another operation, employing the same apparatus and substantially the same temperatures and pressures, but one in which a cooling medium comprising cold water in amounts equivalent to from one to five per cent of the residual products produced, was fed at a substantially constant rate upon the surface of the residual liquid maintained at a relatively low level in the reaction chamber. The yields obtained were substantially the same as those in the firstmentioned operation, but the yield of residual oil was increased substantially, with a resultant substantial decrease in the formation of coke, gas and pressure distillate bottoms. The residual products recovered in this latter operation were substantially free from suspended coke and B. 8., meeting all requirements as to quality for commercial fuel oil, and was an excellent charging stock for relatively low temperature or liquidvapor-phase cracking operations. As stated, the production of coke was substantially decreased, affording a prolonged operation of the process, and, in addition, the motor fuel produced was relatively sweeter and more stable, with an increase in anti-knock value of about 5% or more benzol equivalent.

I claim as my invention:

In a hydrocarbon oil cracking process of the character wherein the oil is heated to cracking temperature under pressure while .flowing in a restricted stream through a heating zone and thence discharged into the upper portion of an enlarged reaction zone maintained under cracking conditions of temperature and pressure and wherein the heated oil is separated into vapors and unvaporized oil, the improvement which comprises continuously supplying water in liquid state directly to the surface of the unvaporized oil in the lower portion of the reaction zone, removing admixed oil vapors and steam from the reaction zone and dephlegmating the same to condense insufliciently cracked fractions of the vapors as reflux condensate, separating entrained water from the reflux condensate, and then returning the reflux condensate to the heating zone for retreatment therein.

JACOB BENJAMIN HEID.

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