US2006177A - Process for obtaining valuable refined distillates from unrefined hydrocarbon oils an products obtained thereby - Google Patents

Description

June 25, 1935. 6,177

E. B. PECK PROCESS FOR 0 INING VALUABLE REFINED DISTILLATES FROM UNREFINED HYD ARBON OI AND PRO TS OBTAINED THEREBY iled Mar '7, 1950 INVENTOR ATTORNEY Patented June 25, I 1935 UNITED STATES PROCESS FOR OBTAINING VALUABLE RE- FINED DISTILLATES FROM UNREFINED HYDROCARBON OILS AND PRODUCTS OB- TAINED THEREBY Edward B. Peck, Elizabeth, N. J., assignor to Standard-I.

G. Company Application March 7, 1930, Serial No. 433,937

2 Claims.

The present invention relates to the art of obtaining lower boiling hydrocarbon oils from higher boiling unrefined hydrocarbon oils and more specifically comprises an improved process for converting heavy hydrocarbon oils into lower boiling distillate suitable for high grade motor fuel and the like by the action of hydrogen at elevated temperatures and valuable products produced thereby. My improved process will be fully understood from the following drawing and the description thereof.

The drawing is a semi-diagrammatic view in sectional elevation of an apparatus constructed to carry out my improved process and indicates the flow of materials through the process. In a previous application Serial No. 375,675 filed by the present inventor on July 3, 1929 and entitled Process for treating carbonaceous materials the present inventor disclosed a combination process, making use of two component steps namely; cracking and hydrogenation respectively. The present invention is a continuation in part of the former invention.

Referring to the drawing a heavy oil such as crude oil, reduced crude, gas 'oil or the like, is Withdrawn from any convenient storage, not

shown, by a pumpl and forced thereby through a feed line 2 and into and through a heating coil 3 arranged in a suitable fired setting 4. The heated oil is discharged by line 6 into a reaction chamber 1 which is adapted to withstand superatmospheric pressures for example; in excess of 500 or 1000 pounds per square inch. The drum is suitably lagged by an insulating composition 8 to prevent; any substantial loss of heat. Oil is withdrawii from the drum by a line 9 and discharged intoa separation tower l 0, with or without a suitable reduction in pressure at the valve R. Any suitable form of separation tower is satisfactory, but I prefer to provide a cooling or reflux coil II at the-top of the tower and therebelow several fractionating plates l2 which may be fitted with suitable bubble caps and overflow pipes'sfshown. A pan [3 is suitably disposed in the tower and adapted to collect reflux condensed by the coil H. The pan I3 is above the point at which line 9 dischargesinto the tower I and a heavy tarry liquid is'collect'ed in the lower part of the drum indicated at I4 and maybe continuously or intermittently withdrawn to some suitable storage by a line I5. Vapor is withdrawn from the top of the tower by a line l6 which connects with a condenser l1 and a receiver I8 from which the distillate may be taken by line l9 to a gasoline storage tank, not shown, the gas may be. also withdrawn under pressure by line 20. The product collected in the pan I3 is withdrawn from the tower by line 2| preferably at an elevated temperature and may be run into a suitable storage receptacle 22 from which pump 23 takes suction. If desired distillate oil such as kerosene or gas oil may be fed to the storage receptacle 22 from any convenient source from a line 24 and a pump 2411. Pump 23 forces the oil through a line 25 and into a heated coil 26 mounted in a suitable fired setting 21. Hydrogen under high pressure is preferably forced into the inlet of coil '26 from a suitable high pressure manifold 28 and a branch line 29 and the heated mixture of gas and oil either in liquid or vapor phase is conducted from coil 26 into a reaction vessel 30 which may be packed with a suitable catalytic material 3|, the nature of which will be disclosed below. Reaction vessel 30 is constructed to withstand high temperatures and pressures, for example; pressure in excess of 3000 pounds per square inch and temperatures in excess of 900 F. as well as the embrittling effect of hydrogen. Additional hydrogen may be added to the reaction drum at separate points by means of a branch line 32 and separate- inlets 33 and 34. The drum may also be fitted with suitable heating means, for example; internal electrical heaters, not shown, which are of particular use in initially bringing the apparatus to reaction temperature. Ordinarily, however, it is preferable to lag the drum 30 to prevent excessive loss of heat and to omit heaters. The vaporous mixture leaves the drum 30 by a vapor line 35 which connects witha heat exchanger 36 and passes therefrom to a condenser 31 and a receiving drum 38. Condensate comprising gasoline is removed from drum 38 by line 39 to any convenient storage. If desired exchanger 36 may be held at sufficiently low temperature to partially condense the vaporous mixture flowing therethru and in such case the condensate is withdrawn by a line 40 and may be passed by pump 4| back to the inlet of coil 26. On the other hand, if desired, this condensate may be passed by pump 4| into a gas separation drum 42 which is held at a lower pressure and from which gas is removed by a line 43. The oil freed of gas maythen be forced by a pump 44 through a line 45 back to the line- 2 for second passage through the heated coil 3 and the subsequent apparatus.

The gases withdrawn from drum 3B are conducted to a purification system indicated at 4B which may comprise an oil'scrubbing system operated at high pressure capable of removing hydrogen sulfid'e and hydrocarbon constituents from the gas. Purified gas is then recompressed by a booster pump 41 and forced through line 48 to and through exchanger 36 and again int6 the high pressure manifold 28 as noted above. Fresh or makeup-hydrogen'may be added by line 49. desired, hydrogen or the gases obtained from drum 42 may be recompressed and forced into the purification system 46 for recirculation.

I have found that it is particularly desirable to for example; under pressures in excess of atmospheric and preferably from 300 to 1000 pounds per square inch or higher and at temperatures above about 750 F. or 800 F. but preferably above 900 F. with distillate stocks. While any particular cracking equipment known to the art may be used I prefer the type of equipment shown in my drawing which is known as the tube and tank s'ystem. Oil is withdrawn from the drum with or without reduction of pressure and the eflluent mixture is then separated into cuts comprising a heavy tarlikematerial which may have a density heavier than water, an intermediate oil similar to gas oil and characterized by its freedom from asphalt, in other words being a distillate stock, and a light oil boiling below say 400 F. which is suitable for motor fuels or for other uses. process I collect this intermediate fraction comprising a heavy oil free from asphalt and having an aniline miscibility point at least below 140 F.

or preferably below 100 F. and force the same through a hydrogenating ovenat an elevated temperature and pressure. The oil may be fed alone or it may be mixed with any other oil capable of substantially complete vaporization as straight run gas oil, kerosene, middle oils from coal tar, or the like and with recirculated oil, as will be indicated below. The fresh oil fed to the hydrogenation step preferably has an aniline miscibility point below 140 or 130 F. and if above this figure it is desirable to add the lower aniline point stocks such as recycle oil from the hydrogenation unit, or more heavy cracked stocks, or even virgin stock of low aniline point, for example; from Venezuela crude or the like. The oil is heated in a pipe coil heater to an elevated temperature and hydrogen is preferably forced through the heater with the oil. A temperature of 850 F. or above is ordinarily desirable and the oil may or may not be completely vaporized depending on the particular nature of the oil, the temperature and pressure, but on discharging into the reaction chamber 30 it is preferably totally in the vapor phase. Additional hydrogen may be added to the drum to control its temperature which is normally in excess of 900 or even 950 F. As catalytic agents I preferably use materials immune to the action of sulphur and which may be suitably classified as sulfactive catalysts, for example; chromium, molybdenum or tungstic oxide, either alone or in admixture with each other or with other materials such as alkali metal oxides, alkaline earths, zinc oxide, alumina and the like. The pressure in the vapor phase reaction chamber is preferably above about 300 pounds per square inch, but I contemplate operation at greatly increased pressure, for example; 1000 to 3000 pounds per square inch or higher. The quantity of hydrogen circulated is preferably above about 1000 cubic feetper barrel of oil fed and it may be in considerable excess of this 'quam tity, for example; about 5000 cubic feet per barrel of oil fed. The amount of hydrogen will vary somewhat within these limits, for best results, with the nature of the feed stock and other operating conditions. The amount of hydrogen used is known in the art of destructive hydrogenation. I The oil is fed at a rate sufiicient to produce large quantities of gasoline, for example 1 to 3 volumes of oilper volume of reactor space per hour, but it may be higher especially in the upper ranges of In the present temperature. The oil produced by the passage through the reaction drum 30 isof considerably lower boiling point and is admirably adapted to produce high grade motor fuel in that it is char acterized by a low gum content and marked antidetonation characteristics. In fact it may be suitably added to ordinary gasoline to produce premium motor fuels and when obtained from original oil of suitable low aniline miscibility point may be substantially as effective as benzol. Ordinarily 70 to of the oil fed from the cracking system is converted into products boiling within the gasoline range and the heavier fractions may be recirculated either to thehydrogenation unit comprising coil 26 and drum 30 or to the cracking unit comprising coil 3 and drum 1.

As an example of my process I feed gas oil having a gravity of 38.7 A. P. I. and an aniline miscibility point of 163 F. to the cracking unit for a single passage therethru operating at a pressure of 350 pounds per square inch with a coilgoutlet temperature of 870 F. 25% of oil boiling below about 400 F. suitable for gasoline is produced together with 10% of a tarry material and 60% of a gas oil boiling below about 600 F. and having a gravity of about 32 A. P. I. and aniline point of 124 F. The. remaining 5% is coke, gas and loss. This gas oil is then forced into a secondary or hydrogenation unit at a rate of two volumes per volume of reactor space per hour. The average oven temperature is about 970 F. with a pressure of 3000 pounds per square pure hydrogen is 2000 cubic feet per barrel of oil fed. A catalyst comprising magnesium and tungsten oxides is used in the drum and a distillate boiling below about 400 F. andcomprising 87% of the volume of feed is collected.

This-distillate contains less than 25 mg. of gumper cc., contains less than 050% sulphur and is characterized by an anti-detonation value equivalent to an uncracked gasoline from ordinary sweet crude to which 35% of benzol has been added.

As a second example of the-operation of my process, a California gas oil is cracked to produce a substantial yield of gasoline and a distillate stock heavier than gasoline of the following char- This preliminary product is then passed through the catalyzation oven under conditions similar to those of the previous example with the exception that the gas rate is about 1500 cubic feet per barrel of oil fed and the product when out for gasoline shows the following results:

Gravity 41.7 A. P. I. Sulphur 0.016% Initial boiling pt 97 F. Percent 212 F. -1--- 14 Percent 284 F 32 Percent 356 F 65 Percent 374 F 75 Percent 400 F 82 Percent 437 F 94 Final boiling pt... 444 F.

a sweet crude to which 65% benzol has been added. In this run portions heavier than gasoline are continuously recycled so as to obtain an ultimate yield of 89% gasoline on the fresh oil fed. The recycled oil has a gravity of 151 A. P. I. and an aniline miscibility point of 7 F.

Experiments have shown in accordance with the example that gasoline of extremely high antidetonation value is produced from low grade gas oils and their value in my.process is roughly inversely proportional to their value as cracking stocks or as carbureting oils for the gas industry. In other words; I prefer to use gas oils or other heavy distillates with relatively low aniline miscibility points, say below F., 100, 75, or even below 50 F., as the feed to the hydrogen treatment step of my process. Furthermore the initial cracking step is of great value in my process since it reduces the aniline miscibility point of the higher boiling oil. Middle oils from coal tar and the like may be added to the second stages of my process when available.

As has been stated above the products of my process are characterized by pronounced antidetonation properties, especially when produced 1 from stocks of low-aniline miscibility point. The distillate is in many respects similar to ordinary cracked distillate although it is generally much lower in gum and sulphur than most cracked naphthas. The raw distillates are yellow in color, but may be purified in the usual manner with one or two pounds perbarrel of 66 B. sulphuric acid, or other ordinary methods of purifying, such as with absorbent clay or the like. These distillates are marked by one very peculiar property, that is that the heavier fractions boiling above about 280 or 300 F. possess the anti-detonation properties to a high degree. With ordinary naphthas or cracked naphthas the lighter fractions are always better from a knock standpoint than the heavier fractions and for this reason the tendency has been to lower the end point so as to cut out the heavier fractions which are not so good as the lighter ones. This is undesirable from a power standpoint as the heavier fractions have greater calorific value per unit of volume. In my products the fractions boiling above 280 or 300 F. and so on up to 400 to 430-450 or even 550 F. are characterized by anti-detonation properties and therefore may be included in a premium grade of fuel with great advantage, both from the antideton'ation and the power standpoint. The fractions boiling above say 300 F. when separated are equivalent to more than A or even of their volume of benzol from the anti-detonation standpoint, or in other words, these fractions give a knock suppressing effect equivalent to at least their volume of benzol and sometimes even of their volume.

These synthetic products are heavier than gasoline now on the market and usually fall within the range from, 5'7 to 40 A. P. I. The sulphur content is always below .05% and generally below .01%. sufiiciently low to give no difliculty in automotive engines, for example; in the copper dish gum may be below 25 or 15 or even 10 mg. per 100 cc. according to the standard method now in use.

The gum content is also The following are inspections of two naphthas produced by the present process:

Sample I Sample 11 Gravity I. 57.9 AHP I 56.9" A. P I Initial boiling point 93 F. 91 F. F 10.5% 12.5% 158- 17.0% 18.5? 212.. 37.57 35.5 a 221-- 41.0% 38.5% 284-- 60.5% 59.5% 302."- 66.5% 64.5% 374 89.0% 82.0% Final boiling point-.. 416 F. 474 F. Knock rating 2.9 3.5

Sample Sample Sample Sample I II III IV Knock Knock Knock Knock rating rating rating rating Original naptha- 2. 9 3. 5 3. 0 4+ I. B. P. to 250 F 2.6 2.8 0.0 0.0 250 to 325 F"... 5.2 5.2 3.9 5.0 325 to 375 4. 8 3. 2 6. 0 7. 0 375 to 400 3. 0 0. 4 5. 6 10. O 400 to 425 0. 4 0. 0 5. 6+ 14. 0

The finished stock may be cut to any suitable end point for the particular use to which the naphtha is to be put and so as to provide suflicient volatility, but it is desirable to include heavy ends boiling above 430 F. for example, up to 440 and 450 F. 'for automobile fuels, while for tractors or other automotive engines the end point may be considerably higher, say about 500 or between 500 and 550 F.

My invention is not to be limited by any theory of the mechanism of the reactions nor to any specific example which may have been given for purpose of illustration, but only by the following claims in which I wish to claim all novelty inherent in my invention.

1. Process for the production of improved low boiling hydrocarbons suitable for high grade motor fuel from relatively heavier petroleum oils, comprising cracking the oil vigorously at a temperature in excess of 800 F. to produce gas oil having a low aniline miscibility point, segregating from the cracked products a gas oil distillate fraction having an aniline miscibility point below 100 F., passing said fraction in vapor phase at a pressure in excess of 20 atmospheres and a temperature above 900 F. through a reaction zone containing a sulfactive hydrogenation catalyst with a limited amount of hydrogen sufllcient to avoid coke formation and insuflicient to produce saturated products, withdrawing'and cooling the resulting destructively hydrogenated products and separating therefrom a fraction suitable for motor fuel.

2. Process according to claim 1 in which said heavier petroleum oil is a distillate oil and said cracking temperature is in excess of 900 F.

EDWARD B. PECK.

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