US2101517A - Hydrocarbon oil conversion - Google Patents

Description

ec. 7, 1937. J. D. SEGUY HYDROCARBON OIL CONVERSION Original Filed July 5, 1932 Patented Dec. 7, 1937 Ubii'i' S'E'ES FA'ELN'' QEFQE HYDROCARBGN OIL CONVERSION application July 5, 1932, Serial No. 620,776

Renewed March l0, 1837 Claims.

This invention relates to the treatment of hydrocarbon oils and more particularly refers to an improved process and apparatus for the conversion of raw oil charging stock, flash distillation of the residual products of the system and selective further conversion of the intermediate conversion products of the system, all of which are accomplished simultaneouslyy in a continuous operation.

The primary features of the present invention comprise the use of successive cracking stages in a continuous conversion process, raw oil charging stock for the system being supplied to the rst conversion stage, which utilizes the mildest conversion conditions employed in the process,

while intermediate conversion products (reux condensate) from each conversion stage is returned to further cracking under more severe conversion conditions than in the succeeding stage of the system, reflux condensate from the last stage being returned to the first stage, together with the raw oil charging stock.

A reaction or separating zone is employed ahead of the fractionating .step of each conversion stage of the process and residual oils sepa rated in each of these reaction or separating zones are commingled and subjected to further vaporization or flash distillation at reduced pressure. Vaporous products from the residuum revaporizing or flash distilling zone are subjected to fractionation and, as a special feature of the invention, reflux condensate resulting from said fractionation of the flash distilled vapors (hereinafter termed flash condensate, to distinguish it from reflux condensate from the various conversion stages of the process) is selectively returned to that conversion stage of the process employing the conditions most suitable for the further conversion of said flash condensate to produce increased yields of the desired light product, usually motor fuel of high antiknock value.

Any desired number of successive conversion stages may be employed within the scope of the present invention. The desired number may vary with dilerent charging stocks as well as with the diiferent results which it may be desirable to obtain and depend, in practice, upon an economic balance between the cost of operation and the improved results which accrue from selective retreatment of the intermediate products.

The attached diagrammatic drawing illustrates one specific form of apparatus incorporating the features of the present invention in a, three-stage .prcxess1 A more detailed description of the opgy eration of the process is included in the following description of the drawing. Raw oil charging stock for the system is supplied from line i and valve 2 to pump 3 from which it may be fed through line 4, Valve 5, preheating coils 6, 6 and 6 located respectively within the fractionators l, 'l' and l", the preheated raw oil thence passing through line 8 and valves 9 and I8 to heating coil Ii. It will be understood that the raw oil may be preheated in one, any combination or all of the preheating coils 6, 5 and E or may be preheated in any other well known manner, not shown in the drawing, or, when desired, may be supplied, all or in part, direct to heating coil I I by well known means not shown in the drawing.

Heatingcoil I I is located in a furnace I2 which supplies the heat required for the desired degree of conversion in this heating coil. The heated oil is discharged through line I3 and Valve I 4 into reaction chamber I5 wherein residual liquid is separated from the vaporous conversion products. The residual liquid is withdrawn from chamber I5 through line I6 and valve Il to further treatment, as will be later described. The vaporous conversion products pass from chamber I5 through outlet I8, in separating partition or deck I9 to fractionation in fractionator "E, The vaporous conversion products remaining uncondensed in fractionator 'I are withdrawn through line 2d and valve 2l to condensation and cooling, as will be later described.

Insuiciently converted heavy components of the vapors supplied to fractionator 1 are condensed in this zone as reux condensate and are withdrawn from the lower portion of the fractionator through line 22 and valve 23 to pump 24 from which this reflux condensate from frac tionator l is fed through line 25 and valve 26 to heating coil il', for further conversion.

Furnace I2', of any suitable form, supplies the heat recovered for the desired degree of conversion in heating coil I I' and the heated reflux condensate is discharged through line I3 and valve Ill into reaction chamber I5 wherein residual liquid separates from the vaporous conversion products. The residual liquid is withdrawn from chamber I5 through line I6 and Valve IT to further treatment, as will be later described. The vaporous conversion products from chamber I5 pass through outlet I8', in separating partition or deck I9', to fractionation in fractionator l'. Vaporous products remaining uncondensed in fractionator l are withdrawn through line 20 and valve 2l to condensation, cooling and col- ,lectionJ as will be later described.

The insuciently converted heavy components of the vapors supplied to fractionator 1 are condensed as reux condensate in this zone and are Withdrawn from the lower portion of the fractionator through line 22' and valve 23' to pump 24 from which this reflux condensate from fractionator 1 is fed through line 25 and valve 25 to further conversion in heating coil I I".

The heat required for the desired degree of conversion in heating coil II is supplied from a furnace I2 of any suitable form and the heated reiiux condensate is discharged from heating coil II through line I3" and valve I4" into reaction chamber I5 wherein residual liquid separates from the vaporous conversion products.

The residual liquid is withdrawn from chamberV l5 through line I6 and vatlve I1 to further treatment, as will be later described. Vaporous conversion products pass from chamber, I5 through outlet I8, in separating partition or deck I9", to fractionation in fractionator 1". Vaporous conversion productsV remaining uncondensed in fractionator 1 are Withdrawn through line 29" and. valve 2l" to condensation,

cooling and collection, as'will be latervdescribed.Y

Insuiliciently Vconverted heavy components of the vapors condensed as reflux condensate in fractionator 1 are withdrawn from the lower portion of this zone through line 22" and pass, preferably, through valveY 23" in this line, to pump 24 from which this reflux condensate is fed through line 25 andvalve 26 into line 8, commingling therein with the raw oil charging stock for the system and passing therewith to heating coil II, for further conversion.

Vaporous conversion products of the desired end-boiling point, withdrawn from fractionators 1, 1 and 1, as already described, pass through line 21 and valve 28 to condensation and cooling in condenser 2'9, from which the resulting distillateV and uncondensable gas passes through line 30 and valve 3I to be collected in receiver 32. Uncondensable gas may be released from receiver 32 through line 33 and valve'34. Distillate may be withdrawn from the receiver through line 35 and valve 36.

Residual liquids Withdrawn from the cham'- bers I5, I5' and I5", as already described, commingle in line 31 and pass through valve 38, in this line, to further vaporization in flash distilling chamber 39. Chamber 39 is preferably maintained at substantially reduced pressure relative to that employed in the reaction or separating zones I5, I5 and I5", by means of which reduction in pressure and the latent heat liberated thereby further vaporization of the residual oil is accomplished. The residual oil remaining unvaporized in chamber 39 may be withdrawn therefrom to storage or any desired further treatment through line 40 and valve 4I. Vapors from chamber 39 pass through line 42 and valve 43 to fractionation in fractionator 44.

Vapors of the desired end-boiling point, corresponding to that of the vapors from fractionators 1, 1' and 1", are Withdrawn from the upper portion of fractionator 44 through line 45 and valve 46-and may pass to separate condensation, c ooling and collection, by Well known means not shown in the drawing, or preferablyY commingle l in line 21 with the vaporous products from the other fractionating zones of the system, passing therewith to condensation, cooling and collection ln condenser 29 and receiver 32, as already described. 'When desired, a portion of the distillate from receiver 32 may be withdrawn through line 41 and valve 48 to pump 49 from which it may be returned through line 50 to fractionator 44, or through similar lines not shown in the drawing, to any or all of the fractionating zones of the system to assist fractionation of the vaporous conversion products therein.

Reux condensate condensed in fractionator 44, boiling above the desired end-boiling point of the light vaporous product removed through line 45, as already described, is withdrawn from the lower portion of this zone through line 52 and valve 53 to pump. 54 from which it is fed through line 55, valve 56 and may pass through valve 51, in this line, into fractionator 'I or through line 55 and valve 51 into fractionator 1 or through line 55" and valve 51" into fractionator 1. The zone to which this product is returned will vary with different operating conditions, as well as with variations in the desired products produced by the process, this material being returned selectively to that stage of the system employing the conditions best suited for its further conversion to produce maximum yields of the desired light products, usually comprising motor fuel of high Vantilrnock value.

It is within the scope of the invention to supply a portion or all of the reux condensate from the fracticnator of the last conversion stage of the system (in this case fractionator 1") to the fractionator (in this case 44) Yof the residuum dash distilling stage of; the system. Line 58 having valve 59 is provided in the apparatus illustrated for this purpose. In. Case this alternative is used, the reflux condensate from fractionator 1 or thatV portion ofrit supplied to fractionator 44, commingles with the reflux condensate condensed in fractionator 44 and is returned to the same conversion stage wherein the reflux condensate from fractionator 44 is subjected to further conversion.

The various conversion stages of the process preferably employ substantial super-atmospheric pressures ranging, for example, from 1GO to 800 pounds, or, thereabouts per square inch. Sub-Y ceding stage, conversion temperatures ranging,

for example, from as low as 800 F. at the outlet from the heating coil of the first stage to as high as 1250 F., or thereabouts, at the outlet from the heating coil of the last stage. As already mentioned, the residuum flash distilling zone is preferably operated at substantially reduced pressure relative to that employed in the reaction chambers and this reduced pressure may range, for example, from pounds, or thereabouts, per square inch down to substantially atmospheric pressure.

As a specific example of the operation of the process as it may be practiced in an apparatus such as illustrated and above described, the raw oil charging stock is a 30 A. P. I. gravity gas oil, which is subjected in the heating coil of the primary stage of the system, to Va temperature of about 930 F. at a super-atmospheric pressure of about 275 pounds perrsquare inch. This pressure is substantially equalized in the succeeding reaction chamber and fractionator of this stage. Reux condensate from the fractionator of the first stage is subjected in the heatingcoil of the second stage to' a conversion temperature of ap- PIOXmaSly 950 F. at a super-atmospheric 751 pressure of about 400 pounds per square inch. This pressure is also substantially equalized in the reaction chamber and fractionator of this stage of the system. Reflux condensate from the fractionator of the second stage is subjected in the heating coil of the third conversion stage to a temperature of about 1000 F. at a superatmospheric pressure of about 100 pounds per square inch. This pressure is also substantially equalized in the succeeding reaction chamber and fractionator of this stage of the system. Reilux condensate from the third conversion stage is returned to the heating coil of the first stage. Residual oil from the three reaction chambers is subjected to flash distillation at a reduced pressure of about 30 pounds per square inch. Flash condensate resulting from fractionation of the vapors from the flash distilling chamber is returned to the fractionator of the first conversion stage whereby it is subjected to further treatment in the heating coil of the second stage. This operation may yield, per barrel of raw oil charging stock, about 68 percent of motor fuel, having an antiknock value equivalent to an octane number of about 78, about percent of good quality residual oil and about 1000 cubic feet of uncondensable gas.

In an operation such as above described, when the ash condensate is returned to the fractionator of the second conversion stage and thereby subjected, together with reflux condensate from this Zone, the conversion conditions employed in the third conversion stage of the systern, the antiknock value of the motor fuel product of the system is somewhat improved but the gas loss is increased and, for the same yield of motor fuel, a lower yield of residual oil is recovered.

Again in an operation similar to that rst described, except that the flash condensate is returned to the fractionator of the third conversion stage and supplied therefrom, together with reflux condensate from this zone to the heating coil of the first conversion stage, the yield and quality of residual oil may be increased at the expense of the antiknock value of the motor fuel product, the yield of motor fuel being approximately the same and the yield of gas somewhat lower.

I claim as my invention:

1. In a process for the conversion of hydrocarbon oil wherein the oil is subjected to conversion temperature at superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, wherein vaporous and residual liquid conversion products separate, vapors from the reaction chamber subjected to fractionation, reux condensate from the fractionator subjected to further conversion at superatmospheric pressure in a separate heating coil and communicating enlarged reaction chamber wherein vaporous and residual liquid conversion products separate, vapors from said separate reaction chamber subjected to separate fractionation, reux condensate from said separate fractionator subjected to further conversion at superatmospheric pressure in another separate heating coil and communicating enlarged reaction chamber wherein vaporous and residual liquid conversion products separate and vapors from the last mentioned reaction chamber subjected to separate fractionation, and the overhead vapors from the fractionation stages condensed and collected, the improvement which comprises withdrawing unvaporized residual oil from each reaction chamber, commingling the vresidual oils and subjecting them to further vaporization at reduced pressure, subjecting the resulting vapors to fractionation, supplying to the last mentioned fractionating stage reflux condensate from the fractionator to which vapors from the last mentioned reaction chamber are supplied and returning reux condensate from said last mentioned fractionating stage to the system for further conversion.

2. A process ofthe character dened in claim l, wherein reflux condensate from said last mentioned fractionating stage is returned to at least one heating coil of the system.

3. A process of the character defined in claim 1, wherein portions of the reflux condensate from said last mentioned fractionating stage are returned to more than one heating coil of the system.

4. A cracking process which comprises heating hydrocarbon oil to crackin-g temperature under pressure and separating the same into vapors and urivaporized oil, introducing the vapors to a fractionating zone and fractionating the same therein to condense and separate insu-iciently cracked fractions thereof, flash distilling the unvaporized oil by pressure reduction and dephlegmating the ashed vapors independently of the iirst named vapors, introducing resultant ilash redux to said fractionating zone as a dephlegmating medium for the vapors therein thereby forming a composite reux condensate of the insufliciently cracked fractions and flashed fractions, subjecting such composite reflux condensate to independently controlled cracking conditions of temperature and pressure, fractionating the additional cracked vapors thus formed independently of the flashed vapors and flash distilling the unvaporized portion of the independently cracked composite reux condensate in admixture with said unvaporized oil, and nally condensing the fractionated vapors.

5. A conversion process which comprises subjecting hydrocarbon oil to cracking temperature under superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, separating vapors from residual oil in the chamber, fractionating the vapors and subjecting resultant reflux condensate to further conversion at superatmospheric pressure in a separate heating coil and communicating enlarged reaction chamber, separating vapors from residual oil in the last-named chamber and fractionating' these vapors independently of the first-named vapors, withdrawing residual oil from each of the chambers, commingling the residual oils and subjecting them to further vaporization at reduced pressure, fractionating the resultant vapors in contact with reflux condensate formed in the second-mentioned fractionating step, returning reflux condensate from the third-mentioned fractionation to the system for further conversion, and finally condensing and collecting the overhead vapors from the fractionating stages.

6.A conversion process which comprises subjecting hydrocarbon oil to cracking temperature under superatmospherc pressure in a heated coil and communicating enlarged reaction chamber, separating vapors from residual oil in the chamber, fractionating the vapors and subjecting resultant reflux condensate to further conversion at superatmospheric pressure in aseparateheating coil and communicating enlarged reaction chamber,separating vapors from residual oil in the lastnamed chamber and fractionating these vapors independently ofv the first-named vapors, Withdrawing residual oil from each of the chambers, commingling the residual oils and subjecting them to further vaporization at reduced pressure, fractionating the resultantV vapors in contact with reflux condensate formed in the secondmentioned fractionating step, returning reux condensate from the third-mentioned fractionation to the first-named heating coil for further conversion, and nally condensing and collecting the overhead vapors from the fractionating stages.

'7. A conversion process which comprises subjecting hydrocarbon Voil to cracking temperature under superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, separating vapors from residual oil in the chamber, fractionating the vapors and subjecting resultant reilux condensate to further conversion at superatmospheric pressure in a separate heating coil'and communicating enlarged reaction chamber, separating vapors from residual oil in the last-named chamber and fractionating these vapors` independently of the first-named vapors, withdrawing residual oil from each of the chambers, commingling the residual oils and subjecting them to further vaporization at reduced pressure, fractionating the resultant vapors in contact with reiiux condensate formed in the second-mentioned fractionating step, returning reflux condensate Vfrom the third-mentioned fractionation to thev second-mentioned heating coil for further conversion, and nally condensing and collecting the overhead vapors from the fractionating stages. Y

8. A conversion process which comprises simultaneously subjecting hydrocarbon oils to independently controlled cracking conditions of temperature and'pressure in a series of cracking zones maintained at successively higher temperatures, separately removing vapors and unvaporized oil from each of said zones and introducing the vapors from each of the cracking zones to a separatel fractionating zone, fractionating the vapors in the fractionating zones to condense heavier fractions thereof, supplying reflux condensate from a fractionating zone receiving vapors from a relatively low temperature cracking zone to the cracking zone of next higher temperature in the series, combining the unvaporized oils withdrawn from the cracking zones and flash distilling the resultant mixture by pressure reduction, fractionating the resultant ilashed vapors independently of the vapors from the cracking zones, introducing ash reflux thus formed into said fractionating zone receiving vapors from a relatively low temperature cracking zone as a dephlegmating medium and to be supplied with said reflux condensate to said' cracking zone of next higher temperature, and finally condensing the fractionated vapors.

9. A hydrocarbon oil conversion process which comprises subjecting the charging oil to cracking conditions of temperature and pressure in a rst cracking zone,V separately removing vapors and unvaporized oil from said zone, fractionatlng the vapors and supplying resultant reflux condensate to a second cracking zone, cracking the reflux condensate in said second zone at higher temperature than the charging oil in said rst zone and separately removing vapors and unvaporized oil from the second zone, fractionating the vapors from the second zone and combining the unva- `porized oil from this zone with that withdrawn from the rst zone, flash distilling the resultant mixture of unvaporized oils by pressure reduction, fractionating the resultant ashed vapors and introducing flash reux thus'formed into contact with the rst-mentioned vapors undergoing fractionationA as a dephlegmating medium thereof and tobe supplied with said reflux condensate to the second cracking zone, and finally condensing the fractionated vapors.

10. A conversion process which comprises simultaneously subjecting hydrocarbon oils to independently controlled cracking conditions of temperature and pressure in a series of at least three cracking zones maintained at successively higher temperatures, separately removing vapors and unvaporized oil from each of said zones and introducing the vapors from each of the crackingzones Sto a separate fractionating zone, fractionating the vapors Vin the fractionating zones to condense heavier fractions thereof, supplying to the first or lowest temperature cracking zone in the series reux condensate formed in the fractionating zone receiving vapors from the last or highest` temperature cracking zone of the series, supplying to the second cracking zone in the series reiiux condensate formed in the fractionating zone receiving vapors from said first cracking zone, supplying to the third cracking zone in the series reiiux condensate formed in the fractionating zone receiving vapors from said second crackingY zone, combining the unvaporized oils Withdrawn from the cracking zones and Ilashdistilling theY resultant mixture by pressure reduction, fractionating the resultant flashed vapors independently of the vapors'from the cracking zones, introducing ash reux thus formed into said fractionating zone receiving vapors from the last cracking zone of the series as a dephlegmating medium and to be supplied with the rst-mentioned reiiux condensate to said rst cracking zone, and finally condensing the fractionated JEAN DELATTRE SEGUY.

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