US2176318A - Process for hydrocarbon oil conversion - Google Patents

Description

Oct. 17, 1939. J G, ALTHER l 2,176,318 v Pnocss's Fon HYvRocARoN on. CONVERSION 'Filed Nov. 30, 1936 @afge/T157 5913071222275? or 1 Y Colli?? (Wauzer Patented Oct. 17, 1939 UNITED STATES PATENT OFFICE PROCESS FOR HYDROCARBON OIL CONVERSION l Application November 30, 1936, Serial No. 113,428

4 Claims.

This application is a continuation-in-part of my copending application Serial #355,704-filed April 17, 1929, now Patent No. 2,091,261.

'This invention particularly refers to an im- 5 proved process for the selective pyrolytic conversion of dilerent hydrocarbon oil fractions wherein intermediate liquid conversion products of the process are subjected to conversion in one cracking stage, the resulting vaporous products subjected to further conversion in a correlated but independently controlled cracking stage, hydrocarbon oil charging stock for the process supplied to an intermediate point in the system and residual liquid products of the first cracking operation subjected to further Vaporization within the system at substantially reduced pressure.

One specific embodiment of the invention comprises subjecting hydrocarbon oil, comprising intermediate liquid products recovered from Within the system, as later described, to cracking temperature at superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, separately removing the resulting vaporous and liquid conversion products from the reaction chamber, supplying the latter to a vaporizing chamber preferably operated at substantially reduced pressurerelative to that employed in the reaction chamber, subjecting said vaporous conversion products to further cracking in a separate heating coil, introducing the products from said separate heating coil into the vaporizing chamber, separating vapors from non-vaporous residual products in the vaporizing chamber, subjecting the vapors to fractionation, whereby their components boiling above the range of the desired final light distillage product of the process are condensed as a reux condensate, supplying reflux condensate, comprising said interjmediate liquid products, to the rst mentioned heating coil, subjecting fractionated vapors of the desired end-boiling point to condensation, recovering and separatingthe resulting distillate and gas and supplying hydrocarbon oil charging stock for the process to the reaction chamber or to the vaporizing chamber, or in part, to both, as desired.

The processis particularly well adapted to the treatment of charging stocks of relatively wide boiling range such as crude petroleum, topped crude and the like. It is, however, applicable to the treatment of practically any type of charging stock ranging from heavy residual oils through the various fractions of crude petroleum and cracked products to and including materials within the boiling range of gasoline and specifically including mixtures of hydrocarbon oils of dierent characteristics.

There are several alternative non-equivalent methods of treating the charging stock, depending upon its point of introduction into the system; and selection of the method employed will depend, primarily, upon the nature of the charging stock and the desired results, which may be varied to suit requirements. For example, when the charging stock consists of or contains a substantial quantity of materials boiling within the range of the desired final light distillate product of the process (such as gasoline) but which are unsatisfactory as components of the final light distillate product, it is preferably supplied to the reaction chamber. `By this method of operation such unsatisfactory low-boiling components of the charging stock are vaporized and subjected to cracking or reforming in the succeeding heating coil While any high-boiling components of the charging stock, which remain unvaporized in the reaction chamber, are removed therefrom with the liquid conversion products of the first cracking operation and subjected to further treatment therewith. This method of operation may also be utilized whenever the charging stock contains an appreciable quantity of components which are desirable as cracking stock in the second mentioned cracking operation. In case it does not contain any appreciable quantity of undesirable components boiling Within the range of the final light distillate product it may be supplied to the vaporizing chamber succeeding the second mentioned heating coil. By the latter method of operation any high-boiling components of the charging stock remaining unvaporized in the vaporizing chamber will commingle with the residual conversion products in this zone and be recovered therewith, while any lower boiling vaporous components will pass from the vaporizing chamber to the fractionator, wherein their components, boiling above the range of the desired light distillate product, Will collect With the reflux condensate and be subjected to cracking there- With in the first mentioned heating coil, vaporous products from which are subjected to further cracking in the second mentioned heating coil.

The process may be operated for the production of either liquid residue or coke in the vaporizing chamber and, in case it is desired to recover good quality liquid residue in this zone, the highly heated products discharged from the second mentioned heating coil are preferably cooled, prior to their introduction into the vaporizing chamber, suciently to prevent their excessive further conversion in this zone and to maintain the desired temperature and thereby control the degree of vaporization in the vaporizing chamber. This cooling of the stream of heated products from the second mentioned heating coil may be accomplished by commingling therewith either a regulated portion or all of the charging stock and/or a regulated portion or all of the liquid products from the reaction chamber, the commingled materials being supplied to the Vaporizing chamber.

The features and advantages vof the invention as well as the various alternative methods of operation providedwill be more apparent with reference to the accompanying diagrammatic drawing and the following description thereof. The drawing illustrates one specific form of apparatus embodying the features of the invention and wherein the process of the invention may be accomplished. l

Referring to the drawing, relatively low-boiling oils recovered from within the system are supplied, as will be later described, to heating coil I wherein they are subjected, by means of heat supplied by furnace 2, to the desired cracking temperature preferably at a substantial superatmospheric pressure` The heated products are discharged from heating coil I through line 3 and valve 4 into reaction chamber 5.

Chamber 5 is also preferably maintained at a substantial superatmospheric pressure and, although not indicated in the drawing, is preferably insulated to conserve heat, whereby the heated products supplied to this zone are subjected tc continued conversion. Vaporous and liquid products are separated in chamber 5, the latter being withdrawn from theV lower portion of this Zone through line 6 and valve 'I to pump 8 wherefrom they are directed through line 9 and may be introduced, all or in part, either through valve Ilin thisline into chamber 20 or through line II, valve I2 and line.I3 into line IlB and thence, together with cracked products from heating coil I5, into chamber 20.. When the superatmospheric pressure employed in chamber 5` is suiciently higher than the pressure employed in the Zone to which the liquid products from chamber 5 are directed to maintain the desired oil velocity in the lines through which said liquids are passed, pump 8 may be dispensed with by removing the sameV from the system or by bypassing the pump in any well known manner, not indicated.

Vapors are separately removed from any desired point in chamber 5, being withdrawn, in the case here illustrated, from the upper portion of the reaction chamber,` and are directed through line I4 and valve l5 to further cracking in heating coil I6.

Although it is entirely within the scope of the invention to employ a suitable pump or compressonnot illustrated, in line I4 for forcing the vapors from chamber 5 through heating coil I6 and the communicating lines, the fact that pumps or compressors for this class of service are not readily available ordinarily precludes this type of operation and it is therefore preferable to maintain a vsuflcient superatmospheric pressure in chamber 5 to overcome the pressure drop due, to friction and loss of heat in heating coil I6 and the communicating lines, and to maintain the desired pressure conditions in this zone. A pump or compressor is therefore not illustrated at this point in the drawing.

The vaporous materialsl passing through heating coil I6 are subjected therein to the desired cracking temperature at any desired pressure ranging from substantially the same as that employed in chamber 5, or even higher in case a pump or compressor is utilized, down to substantially atmospheric pressure. Heat is supplied to coil I6 by means of a suitable furnace I'I. 'I'he heated products are discharged from heating coil I5 and may pass through valve I9 into chamber 20, either with or without first being partially cooled by commingling in line I8 with liquid products from chamber 5, in the manner previously described, or with charging stock, as will be later described.

Chamber 2i] is preferably operated at a substantially reduced pressure relative to that employed in chamber 5, although it may, when desired, be operated at a pressure up to substantially the same as that employed in heating coil I6. Vaporous'and residual products are separated in chamber 2i? and the latter may, when desired, be reduced to substantially dry cokev in this zone or they may be withdrawn as residual liquid from the lower portion thereof through line 2l and valve 22 to cooling and storage or to any desired further treatment, including, when desired, subsequent reduction to coke.

Vaporous products, comprising vaporous components of the conversion products from heating coil i6 and including any components of the charging stock or the liquid products from chamber 5 which are supplied to chamber 20 and vaporized therein, are removed from` the upper portion of this zone and directed through line 23 and valve 24 to fractionation in fractionator 25.

The components of the vaporous materials supplied to fractionator 25 boiling above the range of the desired final light distallate product of the process are condensed in this zone as reflux condensate. The reflux condensate is removed from the lower portion of the fractionator through line 26 and valve 2'I to pump 28 by means of which it is suppliedthrough line 29 and valve 36 to cracking in heating coil I, in the manner previously described.

Fractionated vapors of the desired end-boiling point are removed, together with gaseous products of the process, from the upper portion of the fractionator and directed therefrom through line SI and valve 32 to condensation and cooling in condenser 33. The resulting distillate and uncondensed gases pass through line 34 and valve 35 to collection and separation in receiver 36. The uncondensed gases may be released from receiver 35 through line 3l and valve 38. Distillate may be withdrawn from receiver 36 through line 5g and valve 5 to storage or to any desired further treatment.

When desired, regulated quantities of the distillate collected in receiver 36 may be recirculated by well known means, not illustrated in the drawing, to the upper portion of fractionator 25 to serve as a refluXing and cooling medium in this zone for assisting fractionation of the Vapors and to maintain the desired vapor outlet temperature therefrom.

Charging stock for the process, comprising any desired type of hydrocarbon oil, is supplied through line I and valve 42 to pumpl 43 by means of which it is fed through line 44 and may be directed, all or in part, through valve 45 in this line into chamber 5, entering this zone at any desired point or plurality of points therein, although only one point of introduction is shown in the drawing, or the charging stockmay be supplied, all or in part, through line 46, valve 41 and line I3 into line I8 to commingle therein with the heated products from heating coil I6 and pass therewith to chamber 20.

The preferred range of operating conditions which may be employed to accomplish the desired results in an apparatus such as illustrated and above described may be approximately as follows: The heating coil of the rst craclL'ng stage may utilize an outlet conversion temperature ranging, for example, from 850 to 950 F., or more, preferably with a superatmospheric pressure at this point in the system of from to 500 pounds, or more, per sq. in. The reaction charnber may be operated at substantially the same or at a somewhat lower superatmospheric pressure than that employed in the preceding cracking coil. The heating coil of the second cracking stage may utilize any desired superatmospheric pressure ranging from 800 pounds, or mo-re, per sq. in. down to substantially atmospheric pressure and the temperature employed at the outlet from this zone may range, for example, from 900 to 1l00 F. When it is desired to recover liquid residue from the succeeding chamber the temperature of the heated products discharged from the last mentioned heating coil is preferably reduced to Within the range of 650 to 800 F., prior to their introduction into said chamber. The vaporizing and separating or coking chamber may utilize any desired pressure ranging from substantially atmospheric up to substantially the same pressure as that employed at the outlet from the communicating heating coil and the pressure employed in this chamber may be substantially equalized or reduced in the succeeding fractionatng, condensing and collecting portions of the system.

As a specic example of one of the many possible operations which may be accomplished in an apparatus such as illustrated and above described, the charging stock is a Mid-Continent crude of approximately 33 A. P. I. gravity containing approximately 32 percent of straight-run gasoline. A cracking temperature of approximately 940 F. is employed at the outlet from the heating coil of the first cracking stage to which reflux condensate from the fractionator of the system is supplied. A superatmospheric pressure of approximately 400 pounds per sq. in. is employed at the outlet from the heating coil and in the communicating reaction chamber. The total charging stock is supplied to the reaction chamber wherein it commingles with the heated products from the rst heating coil and is subjected therewith to conversion under the relatively mild cracking conditions employed in this zone. Vaporous products from the reaction chamber are subjected in the succeeding heating coil to an outlet conversion temperature of approximately 960 F. and the pressure maintained in this zone is substantially equalized With that employed in the reaction chamber. The heated products discharged from the second heating coil are commingled with the liquid products from the reaction chamber and the commingled materials are introduced into the vaporizing and separating chamber which is maintained at a superatmospheric pressure of approximately 50 pounds per sq. in. Residual liquid' is withdrawn from the vaporizing and separating chamber and the vaporous products from this zone are subjected to fractionation for the formation of reflux condensate which is returned to the rst heating coil. The fractionating, condensing and collecting portions of the system employ pressures substantially equalized with that employed in the vaporizing and separating chamber. This operation will produce, per barrel of charging stock, approximately 68 percent of gasoline having an octane number of approximately '70 by the motor method and about 22 percent of residual liquid meeting market specications for premium fuel oil, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

l. A conversion process which comprises heating hydrocarbon oil in a heating coil to cracking temperature under suflicient pressure to maintain a substantial portion thereof in liquid phase and discharging the resultant vaporous and liquid product into a reaction chamber, also introducing charging oil for the process to said chamber, separating vapors from unvaporized oil in the chamber and separately removing the same therefrom, subjecting such withdrawn unvaporized oil, including liquid products discharged from said coil into the reaction chamber to further vaporization in a second chamber, heating hydrocarbons removed as vapor from the reaction chamber to higher cracking temperature than the oil in said coil and introducing resultant heated products into contact With the unvaporized oil in the second chamber to assist said further vaporization of the unvaporized oil therein, and fractionating and condensing the vapors from said second chamber.

2. A conversion process which comprises heating hydrocarbon oil in a heating coil to cracking temperature under sufficient pressure to maintain a substantial portion thereof in liquid phase and discharging the resultant Vaporous and liquid products into a reaction chamber, also introducing charging oil for the process to said chamber, Separating vapors from unvaporizedl oil in the chamber and introducing the unvaporized oil, including liquid products discharged from said coil into the reaction chamber, to a second chamber, separately removing vapors from the reaction chamber and heating the same to higher cracking temperature than the oil in said coil, discharging the thus heated vapors into contact with the unvaporized oil in the second chamber to assist vaporization of the unvaporized oil therein, fractionating and condensing the vapors from said second chamber.

3. The process as defined in claim 1 further characterized in that said second chamber is maintained under lower pressure than the reaction chamber.

4. The process as defined in claim 2 further characterized in that said second chamber is maintained under lower pressure than the reaction chamber.

JOSEPH G. ALTI-IER.

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