US2139624A - Process for treating hydrocarbon oils - Google Patents

Description

Dec. 6, 1938. J. c MORRELL PROCESS FOR TREATING HYDROCARBON OILS I 2 She'ets-Sheet 1 Originai Filed May 51,, 1930 F-ll II III 1N VEN 7 OR cfizc ue C. Naive)? Dec. 6, 1938. J. c. MORRELL I PROCESS FOR TREATING HYDROCARBON OILS Original Filed May 31, 1930 2 Sheets-Sheet 2 Al: Iv b n d A R n l HWI I IHHII y mum w HWWMM \s M Mn m mwml wn m w u V hmw u A G .N\ \m NW Al|l R %k Jae as 0. Morr s 5 Patented Dec. 6, 1938 UNITED STATES PATENT OFFICE Jacque O. MorrelL-Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Continuation of application Serial No. 458,715, May 31, 1930. This application August 11,

1933, Serial No. 684,747.

3 Claims.

This application is a continuation of my application Serial No. 458,715 filed May 31, 1930, which ple, a crude oil containing any amount of natural gasoline may be first subjected to topping, the residual products from the topping operation being thence subjected to relatively mild conversion under any desired conditions and'vario'us intermediate products from the primary conversion may be subjected to reconversion under condi-. tions best suited for the production of high yields of motor fuel or other desired products. With another type of charging stock, for instance, heavy Mexican residual oil, the flexibility of my process provides for its processing under more ideal conditions. For example, it may be first subjected to mild cracking conditions suitable for converting the least refractory components of oil into the desired products. The residual products from this first operation may then be subjected to various cracking conditions with reflux and/or other intermediate products from the secondary cracking reaction being recycled all or in part back through the same secondary heating element or being recycled, all or in part, and reconverted under different conditions, prefer- ?bly more severe, in another portion of the sys- In general, my improved process provides a method and means of cracking a great variety of charging stocks under conditions which approach the ideal for the particular oil being treated. More specifically it provides a method and means of cracking charging stocks which are composed of a mixture of hydrocarbons each or several requiring different degrees of cracking and different conversion conditions for their decomposition inio high percentages of the most desirable produc s.

The great variety of operating possibilities provided by my process may be best understood by referring to the accompanying drawings in which Figs. 1 and 2 taken together illustrate diagram- Renewed September matically, and not to scale, one form of apparatus suitable for the practice of my invention.

Raw oil supplied through line I and valve 2 may be fed by means of pump 3 through line 4, valve 5, line 6 and valve I to the flash dephlegmator 8 or may pass in part through valve 9 in line 4 to fractionating tower l 0. An alternate arrangement for feeding raw oil which may be used in conjunction with that already described consists in feeding the oil from pump 3 through line i valve l2, passing a part thereof through valve I6 directly to coil l1 and the remainder through valves l3 and 53 and line 14 to fractionating tower l5. All of the raw oil may however, pass through valve IS in line H directly into heating element l1. Heating element I! is located in any suitable form of furnace 29 and the oil supplied thereto is heated to the desired outlet temperature under the desired conditions and is discharged through line 3!] and valve 3i to reaction chamber 32. Vapors from the chamber 32 may pass through line 33, valves 34 and 35 to fractionating tower HL. Unvaporized products from chamber 32 may pass through line 96, valves 97 and 98 into line 26 and thence to heating element 28. Usually higher pressures are employed in heating element 28 than in chamber 32 and in all such cases a pump 33 will be required to feed the unvaporized products from chamber 32 through heating element 28. Pump 36 may be utilized, when required, by opening valves 31 and 38 in lines 39 and 40 respectively, and closing valve 98 in line 96.

Raw oil fed overhead to dephlegmator 8 as described serves to assist fractionation and cooling in this zone and together with the reflux condensate accumulating in the bottom of dephlegmator 8 may pass through line l8 and valve H] to pump 20 which supplies the hot feed through line 2|, valves 22 and 59 in part either through line l4 and valve 53 to fractionating tower IE5 or through valve l3 into line H and thence to heating element I! together with such raw oil as may be fed directly thereto. This hot feed from flash dephlegmator 8 may unite in line H with that portion, if any, of the raw oil feed from line H to fractionating tower I5 and. either or both products, thus fed into fractionating tower l5 assist fractionation and cooling in this tower and the unvaporized portions together with reflux condensate from fractionating tower I5 pass through line 23 and valve 24 to pump 25 which supplies the same through line 26 and valve 21 to the heating element 28. Reflux condensate or combined feed, as the case may be, from fractionating tower l5 and unvaporized products from chamber 32 may be combined in varying proportions in line 26 and these combined products or the latter product alone may be fed to heating element 28.

Heating element 28 is located in any suitable form of furnace setting 4| and the oil fed through this heating element is raised to the desired conversion temperature under the desired pressure conditions and is discharged through line 42 and valve 43 to reaction chamber 44. Vapors from chamber 44 pass through line 45 and valve 46 to fractionating tower l5, from which vapors pass through line 41 and valve 48 combining in line 3-3 with vapors from chamber 32 and passing therewith through valve 35 into fractionating tower i8.

Reflux condensate from dephlegmator IS withdrawn thrown line 23 and valve 24 to pump 25 may be fed through line 26 and valve 21 to heating element 28 as already described or any portion of this product may be diverted from line 26 through valve 49 to be fed through line 50 into line 5i and thence to heating element 52.

Reflux condensate from fractionating tower 50 may be withdrawn through line 54 and valve 54 to pump 55 which supplies this oil through valve 55 and line 5! to heating element 52 in combination with that portion, if any, of the products from tower l5 introduced into line 5| as already described. Any portion of the products from dephlegmator 8 may, if desired, be diverted from line 2i through valve 51 and line 58 to combine in line 5! with the rest of the oil fed to the heating element 52.

Heating element 52 is located in a suitable furnace setting 50 and after being heated to the desired conversion temperature at the desired pressure conditions the heated products may be discharged therefrom through line 6| and valve into reaction chamber 44 where they unite with the conversion products introduced to this same chamber from heating element 28 as already described.

Material in chamber 44 then consists of products from both heating elements 28 and 52. Treatment of the vapors from this chamber has already been described. They pass first through fractionating tower l5 and thence through fractionating tower ill in each of which they are subjected to fractionation, reflux condensate from each zone being withdrawn for further treatment as described. The vapors from the top of fractionating tower l0 which comprise the desired final light product from the system may pass through line 99 and valve 63, may be subjected to condensation in condenser 64 thence passing through line 55 and valve 50 to receiver 6?. Uncondensable gas leaves receiver 61 through line 68 and valve 69 while distillate is withdrawn through line and valve II. If desired, portions of the condensed distillate from receiver 61 may be returned by well known means not shown to fractionating tower H] or to fractionating tower l5, or in part to each to assist fractionating and cooling in these zones and to malntain the desired outlet temperature at the top of the towers.

Unvaporized residual products from chamber 44 which consists of residual portions of the conversion products from both heating elements 28 and 52 may be withdrawn through line 12 and valve 13 and any portion of these products may be removed from the system by means not shown. Preferably these residual products may pass through valve 14, where the pressure on the residual products is reduced into flash distilling chamber 15. Unvaporized products from chamber may be withdrawn and removed from the system through line 16 and valve 11. Any portion of the reflux condensate from tower l0 may be diverted from line 54 through line 18 and valve 19. This oil may be withdrawn all or in part from the system through valve 80 in line "I8, or

all or any portion of it may pass through line 8| and vlave 82 to blend in line 16 with the flashed residual oil withdrawn from chamber 15.

Vapors from chamber 15 pass through line 83 and valve 84 to flash dephlegmator 8 where they are subjected to fractionation, the heavier portions passing through line l8, as already described for further treatment and the lighter portions passing through line 85 and valve 86 to be subjected to condensation in condenser 81 thereafter passing through line 89 and valve 90 to receiver 9|. Uncondensed gas is released from receiver 9| through line 92 and valve 93. Condensed distillate is withdrawn from receiver 9| through line 94 and valve 95.

Conversion temperatures employed in this p-rocess may range from approximately 700 F., to some 1400 R, more or less, and the pressures employed may range from sub-atmospheric to high supenatmospheric pressure of for instance, 2000 pounds per square inch. It will be understood that different temperature and pressure conditions may be, and preferably are employed in the three different heating elements of the process, the oil preferably being subjected to more severe cracking conditions as it progresses through the various elements. In other words, heating element I! may employ relatively mild conversion conditions or conditions below those required for substantial cracking for example from 500 F., to 800 F., depending on the character of the oil. Heating element 23 preferably employs liquid phase cracking conditions more severe than those employed in heating element ll, while heating element 52 may employ cracking conditions still more severe than those utilized in heating element 28 for example, vapor phase cracking temperatures upwards of 1050 F. This general. rule need not be true in all cases, however.

Pressure conditions throughout the entire system may be substantially equalized. Difierent pressures are, however, preferably employed in the various systems of the process and differential pressures may be used between the various component parts of the same system.

As a specific example of one type of operation which may be employed in the apparatus above described and. the results obtained: a 24 A. P. I. gravity California crude oil containing about 10% of naturally contained gasoline is subjected in heating element II to a temperature of about 500 F., under a pressure of about 50 pounds per square inch. A substantial proportion of the crude, including the natural gasoline, is there vaporized in chamber 32 under a reduced pressure of about 30 pounds per square inch. The vapors are introduced into secondary fractionating tower it! also maintained at a pressure of about 30 pounds per square inch.

In this operation the unvaporized oil from chamber 32 is reprocessed in heating element 28 ata temperature of about 850 F., under an increased pressure of about 150 pounds per square inch. Reaction chamber 44 and primary dephlegmator 15 are. maintained under a reduced pressure of about 60 pounds per square inch and approximately one-half of the reflux condensate from dephlegmator i is recycled through heating element 28 and the remainder reprocessed in heating element 52 together with reflux condensate from the tower ii! at a temperature of about 1000 F., under a pressure of about 60 pounds per square inch. Products from heating element 52 are introduced into reaction chamber 44 together with the products from heating element 28.

Separation of liquid and vapor occurs in reaction chamber 44, but substantially no liquid level is maintained therein, the liquid being continually withdrawn without accumulation to the flash distilling zone. Vapors from reaction chamber 44 are fractionated in dephlegmato-r I5 and fractionated vapors from dephlegmator l5 combine with the vapors from chamber 32 and the combined vapors are subjected to fractionation in secondary fractionating tower iii. Reflux condensate from flash dephlegmator 8 is fed in part overhead to dephlegmator I5.

With this type of operation a total yield of about 70% of motor fuel is obtained. This yield is based on the crude oil charged including the 10% of gasoline contained in the charging stock and the gasoline recovered from the flashed distillate. This product possesses anti-knock characteristics rendering it suitable for sale as premium motor fuel. About 5% of pressure distillate bottoms may remain after rerunning the flash distillate and about 18% of residual oil may be recovered from the flash distilling system.

Generally and within limits the higher the temperatures maintained in heating elements 28 and 52 the higher will be the anti-knock value of the gasoline produced. The gas yield will also be increased and the temperatures are regulated to prevent excessive gas production unless this is one of the primary aims of the operation.

The process may be operated to produce motor fuel, gas and coke only or the yield of gas and coke may be reduced to a minimum with motor fuel and fuel oil as the principal products.

It is obvious that the examples given are illustrative of only a few methods of operating the process of the invention, and hence are not to be construed as limitations upon the broad scope of the invention.

I claim as my invention:

1. A process for treating crude oil which comprises heating the crude sufficiently to vaporize light and intermediate fractions thereof and separating the same into vapors and unvaporized oil,

; fractionating the vapors to separate the intermediate fractions as reflux condensate from the light fractions, subjecting the unvaporized oil to cracking conditions of temperature and pressure, heating the reflux condensate in a heating zone to higher cracking temperature than and then commingling it with the unvaporized oil, separating the resultant mixture into vapors and residual oil, fractionating and condensing the last-named vapors, flash distilling said residual oil by pressure reduction, fractionating the resultant flashed vapors to condense heavier fractions thereof as flash reflux, retreating a portion of the flash reflux in admixture with said unvaporized oil, supplying another portion of the flash reflux to said heating zone for heating therein in admixture with said intermediate fractions of the crude, and finally condensing the fractionated flashed vapors.

2. A hydrocarbon oil conversion process which comprises topping crude oil containing natural gasoline to form a vaporous fraction and a heavier liquid fraction, heating the liquid fraction to cracking temperature under pressure in a heating zone and separating the resultant products into vapors and residue in a separating zone, removing vapors from the separating zone and fractionating the same independently of said vaporous fraction of the crude and out of contact with the crude oil undergoing topping to condense heavier fractions thereof as reflux condensate, returning at least a portion of said reflux condensate to the heating zone for retreatment together with said liquid fraction, combining the fractionated vapors with said vaporous fraction of the crude and fractionating the commingling vapors, cracking reflux condensate formed by the second-mentioned fractionation independently of and at higher temperature than said liquid fraction of the crude and discharging the resultant heated products into the separating zone for separation into vapors and residue therein, and finally condensing the vapors uncondensed in the second-mentioned fractionating step.

3. A process for treating crude oil containing natural gasoline which comprises heating the crude sumciently to vaporize gasoline and heavier fractions thereof and separating the same into vapors and unvaporized oil, fractionating condensing the vapors to form a gasoline distillate and reflux condensate heavier than gasoline, cracking the unvaporized oil in a heating zone under sufiieient pressure to maintain a substantial portion thereof in liquid phase and separating the resultant products into vapors and residue in a separating zone, cracking said reflux condensate substantially in vapor phase in a second heating zone at higher temperature than the oil in the first-named heating zone, introducing the heated products from said second zone into the separating zone, removing vapors from the separating zone and fractionating the same independently of the first-mentioned vapors and out of contact with the crude oil and said unvaporized oil to form additional reflux condensate, supplying a portion of said additional reflux condensate to the first-named heating zone for retreatment together with said unvaporized oil, and supplying another portion of said additional reflux condensate to said second heating zone for vapor phase cracking therein together with the first-mentioned reflux condensate.

JACQUE C. MORRELL.

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