US2291276A - Treatment of hydrocarbon distillates - Google Patents

Description

July 28, 1942.

w. L. BENEDVlc'r TREATMENT OF HXDROGARB-ON DISTILLATES Fil'ed March 3l, 1939 Patented July 28, 1942 TREATMENT F HYDROCARBON DHSTILLATES Wayne L. Benedict, Chicago, Ill., assigner to Universal Oil Products Company, Chicago, lll., a

corporation of Delaware Application March 31, 1939, Serial No. 265,218

3 Claims. (Cl. 196-30) The present invention is particularly directed to the treatment of hydrocarbon distillates of gasoline boiling range and more specifically to the treatment of cracked motor fuels obtained by the thermal decomposition of petroleum oils, or of oils or tars, obtained by the destructive distillation of oil shales, coal tars, Wood tars, and the like.

The refining of cracked gasoline distillates has been achieved in the past by one of several methods. Outstanding among these is the use of sulfurlc acid by which sulfur and other undesirable components of the-gasoline are removed.

Other refining methods which have been used include contacting cracked motor fuels with natural and activated adsorbent earths. This process is often used in conjunction with gum inhibitors which increase the storage stability and decrease the copper dish gum content of the finished motor fuels. The use of inhibitors sometimes replaces other refining methods entirely.

Untreatedmotor fuel usually requires sweetening to improve the odor and this is done by one of several methods, such as the well known doctor treating method, copper sweetenlng, or hypochlorite sweetening. The addition of the inhibitor to prevent auto-oxidation and gum formation follows the sweetening step.

Still another method which has been used commercially is the treatment of cracked distlllates by contact at elevated temperatures with alloys of zinc and copper, zinc-containing ores, and the like in the presence of hydrochloric acid. The acid is either injected simultaneously with the gasoline or else the latter is pretreated with strong hydrochloric acid solution. These include synthetic zinc-silica hydrogels. 'Ihe process produces gasoline of good color and storage stability. It is with modications of the above process that the present invention is concerned.

In one specic embodiment the invention comprises treating cracked gasoline with relatively strong hydrochloric acid, separating the gasoline, contacting it in a primary treating step at treating conditions with a partially used powdered reagent from a later step, said reagent containing zinc or an oxide of zinc as one major treating component, separating the gasoline from the spent reagent and high-boiling bottoms, contacting said separated gasoline with fresh powdered treating reagent in a second treating step at treating conditions, removing the treated gasoline, returning the partially spent reagent and high-boiling bottoms to the aforementioned primary treating step,

recovering the spent reagent 5.5

after the primary step, regenerating said spent reagent by treating with a volatile alkaline reagent such as ammonia or ammonium hydroxide followed by burning in the presence of air, and returning said reagent to the second treating step.

It has been noted that during the earlyY stages videda method of regenerating the reagent so that it can be used over again for an indefinite number of times.

According to the present invention the gasoline is contacted at atmospheric temperature with a concentrated solution of hydrochloric acid (approximately 25-40%) the sludge permitted to settle out and withdrawn to Whatever method of disposal has been provided for it. Contacting with the acid may be carried out Aby any of a number of ways, among which the countercurrent types are the most suitable. The acid treated gasoline is heated by passage through a heat exchanger and if necessary through a coil disposed in a furnace. The gasoline then mixes with heavy bottoms containing suspended I in them partiallyspent reagent from the second treating step and the mixture passes through a suitable primary reactor where the treating eiect occurs. Generally the temperatures used in this step are moderate. If the gasoline were fractionated at this point it would be found to be of good color and relatively low gum content. The reactor may be any suitable type, the purpose being largely to insure adequate contact and sufficient time for the reaction to take place. Among those which have been found useful are baie columns, orifice mixers, mechanical agitators, etc. The reaction is carried out at sufficient pressure to'maintain the major portionA of the gasoline in the liquid phase (1GO-500 pounds per square inch) and temperatures of the order of 250 F. to 400 F. and may be suitably of the order of 300 F. The partially treated gasoline then passes to a flash separator where the pressure is reduced and the gasoline is flashed oif, while the mixture of heavy bottoms and v1 into sludge separator I2.

spent reagent is continuously withdrawn 'and passed through a device whereby the polymers are removed from the reagent. Such a device may comprise a lter press, or a settler from which the spent reagent can be removed readily. The vapors from the flash separator are cooled sufficiently to condense ythem and passed to a slurry pot where fresh reagent is added and the mixture agitated to keep the powder in suspension. The mixture is pumped through a heating coil into a second reactor similar to that employed in the rst or primary treating stage. The temperature is usually somewhat higher than that used in therst stage, being of the i order of 30D-550 F. and preferably about 400- 450" F. The pressure range used is approximately the same as for the primary step. The mixture of reagent and distillate then passes into a fractionator and the finished gasoline recovered. The high-boiling bottoms and suspended reagent are continuously removed from the fractionator and returned hot to the primary treating step.

The spent reagent from the primary step is separated from high-boiling polymers and may be washed with naphtha if desired to remove the remaining occluded polymers. The reagent is treated with a. solution of ammonium hydroxide or gaseous ammonia or other Volatile alkaline compounds such as amines, etc., to convert any remaining zinc chloride to the hydroxide. The mixture is passed to a furnace or kiln and heated in the presence of air to temperatures in excess of 900 F. but suitably below 1800 F. to prevent substantial sublimation of zinc oxide. In this way carbonaceous material 'is burned off and zinc sulde is converted to the oxide. After regeneration the reagent is taken from the kiln to storage from which it may be passed to the second treating step. The ammonia used is recovered as ammonium chloride which sublimes during the burning step and may be taken into solution and converted to ammonia in a separate step by treatment with burned lime.

One embodiment of the present invention is illustrated diagrammatically by the attached drawing which should not be construed as limiting it to the exact conditions or apparatus used. The apparatus has not been drawn to scale or proportioned exactly.

The gasoline enters the system through line I, valve 2, pump 3 and valve 4 and is mixed in line 5 with hydrochloric' acid which enters from line 8, valve 9, acid pump l0 and valve II. The hydrochloric acid and gasoline are thoroughly mixed in a mixer 6 and passed through valve The acid sludge is wthdrawn from the separator through line I3 and valve I4. 'I'he gasoline passes through line I5, valve i6, heat exchanger I1 and is mixed in line I9 with high-boiling material containing.

partially spent powdered reagent from fractionator 40, by way of line i8. A heating coil may be interposed in line I9 providing additional heat is needed. The mixture passes through valve 20 into the primary reactor 2l which is illustrated as being a bailied tower but may be any suitable arrangement wherein suii'icient contact and time for reaction takes place. Them'ixture leaves the reactor by line 22 and valve 23, passes into ash separator 24 at a reduced pressure and maintained at sumciently high temperature by means of coil 2d' so that the gasoline is ashed overhead through line 25 and valve 26. The mixture of heavy bottoms and spent reagent is Withdrawn through line 26" and valve 26" 'to the separator and regeneration plant which will be described later. The gasoline vapors pass through line 25, valve 26 and heat exchanger 26 where they are cooled suliciently to condense them. In the slurry pot 21 which may suitably be an inclosed vessel equipped with a mechanical stirrer 21 or other device for maintaining the reagent in suspension, the gasoline distillate is mixed with fresh treating reagent from hopper 5l', line 5l and valve 51". The reagent is supplied to hopper 51 from. reagent storage 51 by means of conveyor line 28 and valve 28.

i The slurry passes through line 29 and valve 30 .by means of pump 3l through valve 32 into coil 33 which is disposed in furnace 34. The pressure is increased by means of pump 3l to the desired point which may De approximately 10G-500 pounds per square inch, although ordinarily pressure of -250 pounds is adequate. The gasoline then passes through line 35 and valve 36 into the second reactor 31 which may be similar to reactor 2| and wherein the gasoline is reacted with the fresh treating reagent. The gasoline is drawn through line 38 into yfractionator 40. Gasoline vapors pass overhead through line 4I containing valve 42 and are taken through suitable coolers not shown to storage. Small quantities of ammonia, ammonium hydroxide or caustic solution may be injected into the run-down line in order to prevent corrosion. The gasoline is sweet, of good color, low gum content, and has a good storage life as well as a substantially reduced sulfur content. The polymersy or high-boiling bottoms formed during treating together with the partially spent reagent are drawn through line I8 and valve 43 and recirculated as was previously described in line I9 and thence through valve 20 into the rst reactor.

Line 45 and valve 44 serve as a means for draining the fractionator 40. The mixture of polymers and spent reagent from the flash separator 24 is withdrawn through line 26' and valve 26v into separator 46 which may be a lter press or any sort of separating device whereby the polymers may be withdrawn from the system as through line 41 and valve 48. The spent' reagent is taken by means of conveyor line 49 and valve J9 to mixer 50 where it is thoroughly mixed with gaseous ammonia or a solution of ammonium hydroxide or other volatile alkaline material entering through line 5I and valve 52. The reagent is then conveyed as indicated by line 53 and valve 53 to a kiln or furnace 54 Where it is heated to a temperature in excess of 900 F. with controlled quantities of air in order to reactivate the reagent and burn therefrom the hydrocarbonaceous material. Thel combustion products together with sublimed ammonium chloride pass out of the systeml'ythrough line 55 and valve 55' and may be passed to a suitable cooler` and recovery system Where the ammonium chloride is collected and from which the ammonia may be recovered by suitable means. The regenerated reagent is conveyedlas by line 56 and Valve 56' to reagent storage 51 jfrom which it is taken to hopper 51' by means of conveyor line 28 and valve 28'. The reagent can be introduced into the slurry pot by any convenient method. For instance the reagent can be made into a slurry with a small portion of gasoline or heavy bottoms in hopper 51' and pumped into slurry pot 3l; or the hopper may be tted with a proportioning device for continuously adding the polymers formed and regenerated by mixing powdered reagent. therewith vammonium hydroxide solution and The following example is given to illustrate the burning at a maximum temperature of 1400 F. process and should not be construed as limiting in the presence of air. After regeneration the it to the exact conditions given therein. 5 reagent was found to be equally as active as A Mld-Continent cracked gasoline was treated fresh reagent and was used again in the process.

with 2 pounds per barrel of 35% hydrochloric I claim as my invention:

acid solution and passed through the process del. A process for refining hydrocarbon distilscribed in the foregoing speciiications. The relates which comprises subjecting the distillate to agent used comprised essentially 10% zinc oxide l0 the action of zinc-containing reagent in two aucon pumice ground to pass 100 mesh. The temcessive stages, supplying fresh zinc-containing perature maintained in the primary treating step reagent to the second of said stages and therein was 300 F. at a pressure of 150 pounds per utilizing the reagent to effect a desulfurization square inch. The temperature maintained in of the distillate, and supplying thus used rethe second treating step was 400 F. and the 15 agent from the second stage to the rst of said pressure was 200 pounds per square inch. The stages to improve the distillate with respect to amount of reagent added to the second treating gum and color during the treatment in the inistep was 5 pounds per barrel of gasoline. 'The tial stage. treated gasoline was 30+ color, had a sulfur con- 2. The process as dened in claim l further tent of 0.1%, copper dish gum of 5 mg. and 20 characterized in that the distillate is pre-treated oxygen bomb induction period of 600 minutes. with hydrochloric acid. v The untreated gasoline entering the plant was 3. The process as defined in claim 1 further yellow color, contained 0.18% sulfur, had 150 mg. characterized in that said reagent is regenerated of copper dish gum and an induction period of after its use in said rst stage and then returned 100 minutes. Y 25 to said second stage.

The spent reagent was separated from the WAYNE L. BENEDICT.

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