US2003537A - Process of cracking hydrocarbon oil - Google Patents

Description

J. B. HEID 2,003,537"

PROCESS 0F -CRACKING HYDROCARBON OIL June 4, 1 935.. 7

Filed Dec. 18, 1931 FURNACE 2 FURNACE 3O INVENTOR JACOB BENJAMIN HEID BY @M I ATTORN Patented June 4, 1935 PATENT 0FFlCE PROCESS OF CRACgEG HYDBOCABBON .lacob Benjamin mm, Chicago, 111., assignor to Universal Oil Products Company,

a corporation of South Dakota Application December 18, 1931, s rial No. 581,965

' 4 Claims. (01. 196-49) This invention relates to process of cracking hydrocarbon oil and is more particularly di- -rectedto a combined topping and cracking oper ation as part of acontinuous system. As a feature of the invention, the crude'petroleum is first topped and thereduced crude then distilled and the vapors subjected to reflux condensation and such reflux condensate cracked and again. subjected to reflux condensation and both refluxcondensates returned to the main cracking sys-' tem. in accordance with the present process, the

heat from the main crackingsystem is utilized,

. to top the crude and the reduced crude itselfis preferably also cracked. x

The single. figure of the drawing shows a somewhat diagrammatic view in side elevation of an apparatus suitable for carrying out the invention.

Describing the invention, heating element l is located within any suitable form of furnace 2 and the oil supplied to this zone is heated to the desired conversion temperature preferably under a substantial super-atmospheric pressure. The heated materials pass through line 3, and valve 4 to reaction chamber 5 wherein a substantial superatmospheric pressure is also preferably. maintained. Both liquid and Vaporous conversion products are withdrawn from chamber 5, preferably at a point remote from their point of introduction to this zone, through line 6 and valve I, passing through line 8 into 'vaporizing chamber 9.. I i In starting up the operation, the crude 0 may be supplied through line I, valve H and pumped by means of pump 12 through line l3 controlled by valve ll through line l6, valve ll'and line 8 into the vaporizing'drum 8 from whence it is introduced through line 2i, valve 25 by means of .pump 26 through line 2l,valve 28 into the heating element 29 where suiiicient heat is imparted thereto to vaporize a substantial portion of the crude oil and from which it is introduced into the vaporizing drum 33, vapors therefrom ,passing into. the fractionator l8, through line 36 and valve 31 ultimately furnish? ing enough reflux condensate which, when heated in the heating element I permit'sthe process to be brought to normal'operation as is herein- I from through line l3, ,valve IQ ,preheating coil Chicago, 111.,

I5, line l6 and valve l1 into line 8 and-thence to vaporizing chamber 9. Preheating coil I5 is 10- v cated within fractionator l8 and serves as a means of preheating the raw oil by indirect con-, tact with the relatively hot vapors in the fractionator. It will be understood that other well known means of preheating the crude, such as, 4 for example, by indirect contact with other relatively hot liquid or vaporous materials of the system may be employed instead of or in con- 10 junction with the method illustrated, although such means are well known generally in the art [and are not here illustrated.

Chamber 9 is preferably maintained under a substantially reduced pressure relative to that 15 and liquid conversion products separate in chamber 9, also the relatively light desirable components of the charging stocks are vaporized in this zone and separated from their relatively heavy components .which remain unvaporized. Vaporous materials from chamber 8 pass through 25 line l9 and valve 20 to fractionation in fractionator l8. Non-Vaporous liquid remaining in chamber 9, which comprises residual conversion products and topped crude, is withdrawn from the chamber through line2l and may pass, all or 30 in part, through' valve 22 and line 23 toestorage or to any desired further treatment. However, unless the charging stock and the conversion conditions employed are suchthat the oil withdrawn from chamber 9 is of a nature which would 35 tend to form excessive amounts of coke or carbonaceous material when subjected to further conversion or unless it is desirable to operate the process for the production. of relatively high yields of fuel oil, at least a portion, 11 not all, of the oil from chamber 8 is directed from line 2| through line 24 and valve 25 to pump 28 from which it is supplied through line 21 and valve 28 to further conversion under independently controlled conversion conditions in heat- 45 ing element 29. J1

Heating element 29 islocated in any suitable. form of furnace 30 and the oil supplied to this zone is heated to the desired conversion teinperature preferably under a substantial superatmospheric pressure. The heated materials pass from heating element "through line 8| and valve 32 to reaction chamber 83.

Vaporous and non-Vaporous conversion prodor, if desired, conditions may be so controlled inchamber 33 that the residual material remaining in thisszone is reduced to a substantially dry carbonaceous mass which may be removed from the chamber after the operation of the process is completed. In the latter case a plurality of chambers such as,33 may be employed, although only one is illustrated in the drawing, and may be alternately operated and cleaned or operated 'in'parallel to prolong the operating cycle.

' Vaporous materials v from chamber 33 pass through line 36 and valve 3! to fractionation in fractionator l8, together with vaporous materials from chamber 9 supplied to this zone, as already described. Substantially all of the vaporous materials supplied to fractionator I 8, boiling above the range of motor fuel, are preferably condensed and separated from the components of motor fuel boiling range and gases in this zone. Said relatively heavy high boiling materials collect as reflux condensate in the lower portion of the fractionatorto be withdrawn therefrom through line 38 and valve 39 to pump 40 from which they are-fed through line ll and valve 42 to heating element l for further conversion.

Vapors and gases pass from fractionator l8 through line 43 and valve 44 to be subjected to condensation and cooling in condenser 45, distillate and uncondensable gas from which passes through line 46 and' valve 41. to be collected in receiver 48. ,Uncondensable gas may be leased from' the receiver through line 49 and valve 50. Distillate may be withdrawn from. the- 5 receiver through line 5| and valve 52. A portion of the distillate from receiver '48 may, if desired, be recirculated, by well known means not illustrated in the drawing, to the upper portion of fractionator I8 to assist fractionation of the vapor and to maintain the desired vapor outlet temperature from thiszone.

Pressures employed within'the system may range from substantially atmospheric to superatmospheric, pressures as high as 2000 pounds per sq. in., or more.- Conversion temperatures employed.may range from 800 to 1200 F., more or less. Preferablymeflux condensate from the fractionator of the system. is subjected, in the p imary heating element, to conversion tempera.- res of the order of 900 to 1200" F., substantial super-atmospheric pressures of the orderof to 500 pounds per sq, in., preferably being employed when relatively mild conversion temperatures are utilized, while, with higher'conversion temperatures of the order of 1000 to 1200, F., lower pressures of the order of substantially atmospheric to 100 pounds, orthereabouts, per sq. are preferably employed. Pressures employed in the primary reaction chamber of the system .are preferably equalized substantially with the pressure employed in the primary heating element. Pressures, preferably reduced sub-' stantially below the pressure employed in the primary reaction chamber, are utilized in the vaporizing chamber of the system and may range from substantially atmospheric to about 100 pounds per sq. in. Conversion'conditions of a milder order than those employed in the primary heating element and ranging, for example, from 800 to. 900 F. with super-atmospheric pressures of from 100 to 500 pounds per sq.- in. are'preferably employed in the secondary heating element of the system. The secondary reaction 400 F. and of fairly good antiknock value.

chamber may employpressures substantially .equalized with or lower than those employed in the secondary heating elementranging, for example, from substantially atmospheric to 500 pounds or thereabouts per sq. in. The fractionating, condensing and collecting portions of the system preferablyemploy a pressure substantially equalized with that in the vaporizing chamber.

As a specific example of the operation of the process of the present invention, ,the raw oil charging stock is a mid-continent crude oil containing about 12 percent of material boiling below Reflux condensate from the fractionator is subjected in the primary heating element to a temperature of approximately 920 F. A superatmospheric pressure of approximately 300 pounds per sq. in. is maintained in the primary heating element and reaction chamber. Pressure in the vaporizing chamber is reduced to approximately 50 pounds per sq. in. Residual oil from the vaporizing chamber is subjected, in the secondary heating element, to a temperature of approximately 850 F. under a superatmospheric pressure of approximately 200 pounds per sq. in. A reduced pressure of approximately 50 pounds per sq. in. is maintained in the secondary reaction chamber, which pressure is substantially equalized within the fractionating; condensing and collecting portions of the system. 'Aside from the 12 percent or thereabouts of straight-run gasoline contained within the charging stock, this operation may yield, based on the topped crude,'approximately 665 percent of 400 end-point motor fuel having an antiknock value equivalent to a blend of approximately 70 percent iso-octane and 30 percent nnr- .malheptane. The additional products of the sys- ,tem, based on the topped crude, may be approxi-- to a substantially dry carbonaceous residual product, a yield of residual oil given in the above example may be replaced by about 60 pounds of coke per barrel of topped crude, an increase of approximately 5 percent in the yield of gasoline, an. improvement in its antiknock quality and a somewhat increased gas production.

I claim as my invention:

1. A combined cracking and topping process which comprises subjecting hydrocarbon distillate to cracking conditions of temperature and pressure in a conversion zone, removingthe cracked oil from said zone and introducing the same to a flashing and separating zone maintained under lower pressure than the conversion zone, introducing crude oil containing natural gasoline into the separating zone and partially distilling the same therein, separating the commingled oils in the separating zone into vapors and a mixture .of topped crude and cracked residual oil, subjecting said mixture in a second conversion zone to milder conversion conditions than are maintained in the first-mentioned conversion zone thereby forming additional vapors, combining the latter'with the vapors formed in the separating zoneand frac- 1 2,008,5 3? tionating the commingled vapors to condense heavier fractions thereof, supplying resultant reflux condensate to the first-mentioned conversion zone as said hydrocarbon distillate, and finally condensing the-fractionated vapors.

2. A combined topping and cracking process which comprises passing hydrocarbon distillate, formed as hereinafter set forth, through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated distillate into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing vapors and un vaporized oil as a mixture from the reaction zone and introducing the same to a separating zone maintained under lower pressure than the reaction zone, introducing 'crude oil containing natural gasoline intorthe separating zone and partially distilling the same therein, separating 'the commingled oils into vapors and residual oil in the separating zone and passing the latter to a second heating zone, subjecting the residual oil,-

sidual oil with the vapors separated in the separating zone and dephlegmating the resultant vaporous mixture to condense heavier fractions thereof, supplying resultant reflux condensate to h the first-mentioned heating zone as said hydrocarbon distillate, and finally condensing the dephlegmated vapors.

3. A combined topping and cracking process which comprises passing hydrocarbon distillate,

formed as hereinafter set forth, through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated distillate into an enlarged reaction zone maintained under cracking conditions of temper ature and pressure, removing vapors and unvaporized oil as a mixture from thevreaction zone the separating zone and passing the latter to a second heating zone, subjecting the residual oil,

including the topped crude, in the second heating zone to milder conversion temperature than is maintained in the first-mentioned heating zone, discharging the thus heated residual oil into a second separating zone and distilling the same substantially to dryness therein, combining thevapors thus evolved from the residual oil with the vapors separated in the separating zone and 'dephlegmating the resultant vaporous mixture to condense heavier fractions thereof, supplying resultant reflux condensate'to the first-mentioned heating zone as said hydrocarbon distillate and finally condensing the dephlegmated vapors.

4; The process as defined by claim 2 further characterized in that the charging'oil is preheatedprior to introduction to the separating zone by indirect heat exchange with said vaporous mixture undergoing dephlegmation.

JACOB BENJAMIN HEID.

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