US2301322A - Chemical process - Google Patents

Description

Nov. 10, 1942. E. D. REEVES ETAL 2,301,322'

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AMBER L/.sPEnS/olv 4 n c Acc QMQL A Tok Patented Nov. l0, 1942 CHEMICAL PROCESS Edward D. Reeves, Cranford, and Stewart H.

Hulse, Westfield, N.

assignors to Standard Oil `Development Company, a corporationv of Delaware Application August 31 1939, Serial No. 292,780

2 Claims.

drocarbon oils and refers more particularly to the thermal treatment of hydrocarbons in the presence of a solid substance which adsorbs carbonaceous material formed during the said treatment and also exerts an abrasive action on the walls of tubes and vessels with which the oil It is a matter of record to treat hydrocarbons in the presence of activated carbon for the purpose of catalyzing the cracking of hydrocarbons. Activated carbon hasbeen found to be a fairly active catalyst for various thermal reactions, say where relatively heavy hydrocarbons are converted to hydrocarbons boiling Within the gasoline range.

In the treatment of heavy petroleum materials such as reduced crude containing large quantities of low gravity tar and the like, it is extremely diilicult to convert such feed stocks to valuable products in thegasoline, kerosene and heating oil rangewithout suffering large losses due to gas and coke formation. In addition. thermal treatment of such stocks results inv heavy coke deposits in the heating coils and soaking drums or stills requiring frequent shutdowns and sometimes impairing the equipment.

This invention relates to the treatment of hy- In. copending application Serial No. 267,993. tiled April 4, 1939, there is described and claimed the use of pumice or clay for a similar purpose.

but there the adsorbent required regeneration comes intocontact thus tending to prevent accumulation of tarry deposits thereon.

for further use.

In order to give a more detailed explanation of my present invention, reference is now made to the accompanying drawing which shows diagrammatically and in partial vertical section a suitable apparatus in -which the present invention may be performed. v

And to give a concrete example of this invention, the processing of a heavy gasoil having an A. P. I. specific gravity of 15 and a boiling range of from 450 to 1400" F. will now be described with reference to the drawing. The gas oil may be introduced into the system through line I and then passed throu'gh a furnace 2 where the feed stock is heated to a temperature of aboutv 900 F., the heated stock being then withdrawn through line 3. Simultaneously, a dis- An object of the present invention resides in pressure maintained on the oil in the coil 1 in the use of the coke produced during the conversion of relatively heavy stocks, such as reduced crude, heavy gas oil or the like to form products of lower viscosity and boiling range.

Another object of the present invention involves the use of the coke formed during the thermal treatment of hydrocarbons inthe preliminary treatment of reduced crudes and heavy gas oils prior to a ilnal catalytic treatment employing other adsorbents, such as acid-treated clays, zeolites, synthetic silica-alumina gels, and

the like.

According to the present invention, preferably the coke which is employed in the thermal treatment of hydrocarbons is that formed in a treatment of petroleum, e. g. a cracking operation. 'I'his coke is preferably ground to a powder of a size such that substantially all of it will pass through screens of fromA 100 to 400 mesh. This powder is preferably injected into a petroleum stock, such as reduced crude or a heavy gas oil in the form of a suspension. That is to say. it may be nrst dispersed into a gas, such as steam. nitrogen, hydrogen, or nue gas or mixtures of two or more of these gases and vthen injected into theoil to be treated.

persion ofpowdered coke produced a previous treatment, which coke was disper d in steam in dispersion chamber 4, in a manner hereafter more fully described. was injected into -the heated oil stream through line 5. The heated gas oil containing the powdered coke was then passed through a coil I ink a furnace 8 where thetemperature was increased to about 1000 F. The

the furnace I was about 100 pounds gauge and the time required for the oil t0 pass through'the coil was about 10 seconds. 'I'he ratio of added coke'to oil was about 1 part by weight of coke to 1 part of oil on a cold oil basis. The oil was withdrawn from the coil 'I through line Il and passed to a cyclone separator 9 where the coke was removed from the vapors andpassed down-- wardly over the inclined bailles II in vessel I0. Meanwhile, in order to assist the removal of the vapors from the coke, steam at a temperature of about 1000 F. was introduced into the bottom of vessel I0 through line JI. Themixture of oil vapors and steam was withdrawn through yline I2, passed through a cooler I4 which condensed the water, lthen passed through line I5 to a separator Il where the water separated in allower liquid layer. The cracked products were withdrawn through line I1 to a fractionating tower Il or they might havel been passed directly to. line Il and thence to condenser 20 and nally to an accumulator 2l.

`In the process Just described the operating conditions will of course vary according to numerous factors including the character of theA feed stock, the type of product| desired and other variables. As a matter of fact in the process described the main product would be a crackable stock, i. e. a stock better adapted than the original stock for cracking to form gasoline in a thermal operation or preferably in a 'catalytic cracking operation employing an activated clay catalyst or the like. In producing the above cracking stock, the yield from 1000 lbs. of original material would be, under the conditions referred to, about 950 lbs. of a gas oil boiling within the range of about 400 to 850 F. with about 4.5 lbs. of coke and about 5 lbs. of gas. Y

In general, it may be stated with further referenoe to operating conditions that temperatures of from 750 to 1100 F. may be employed in the coil 1, that the time the oil is resident in the coil may be from 5 seconds to 50 seconds, that pressures of Zero pounds per square inch gauge to `150 lbs. per square inch gauge may prevail in the coil l and the ratio of adsorbent coke to oil in coil 'i on a weight basis and calculated with reference to a unit of cold oil is from about .2 to parts of catalyst to l part of cold oil. Since high temperatures may be employed without excessive coke deposition, the product distr.bution is favorable and conversions per pass are relatively high from high boiling feed stocks. Of course with lower boiling feed stocks operating conditionsA will be less severe as to ternperature and time of reaction.

Referring now to the coke which had been removed from the oil vapors in baled tower l0,

the system through line 22, `passed through superheater 23 and thence through line 24 .into

the chest 4 at a point substantially opposite the discharge end of screw conveyer 36 within the chest. The temperature of this'steam is about l000 to 1100 F. and it impi'nges against the falling coke discharged through screw 3B. The

V amount ofsteam gravimetrically should be about,

2 or 3% ofthe amount of. coke. velocity of the steam is sufficient to form a The linear moving` entrainment jor dispersion of coke in steam. The dispersion of coke is then discharged into line 5 and as previously mentioned, is then discharged intoline 3. The pressure on the steam in chest 4 is of course greater than'that on oil in line 3. Good results are obtained by providing a steam pressure in chest 4 of from 5 to 10 lbs. gauge greater than in oil line 3.

Referring back to the coke in vessel I0, the same is deflected, inv whole or in part, by a swinging damper 31, pivoted at 40 and adapted to be swung about the pivot by a handwheel or the like (not shown) operable outside the pipe 5l into a discharge line 42. The coke will have increased in size by accretion during the passage of the ne powder, introduced through line 5 into the oil stream, through the treating zone. For most commercial purposes, the coke which is withdrawn from the system through line 42 should be in lump form.

On the other hand, if it is desired to obtain a finely divided coke, damper 3l is sei( at a vertical position thus permitting all of the coke to bedischarged into grinding chamber 32. Coke not to be-recycled which is discharged into hopper 35 from chamber 32 is deflected by a` rotatable damper 31A toward conveyer 38 and thus withdrawn from the system. Of course, by obvious manipulation of dampers 3l and 31--A both coarse andy fine coke may be withdrawn from the system. As heretofore stated, the coke to be recirculated should be in the form of a powder.

It will be understood that the mechanical specific means shown and described to carry out the present invention do not constitute a limitation on the invention since obviously other apparatus could ,be employed to accomplish the same or equivalent results.` For example, by employing a compression screw of good efficiency it would be possible to discharge the recirculated coke directly into a shell type reactor thus eliminating the steam chest 4. Also means are availablf for separating the coke from the vapors other than the cyclone separator 9 shown. For instance, fine mesh screens `as Well as electrical precipitators may -be used. It may be necessary in some processes to employ a second cyclone precipitator or a primary cyclone separator and an electrical precipitator to remove all the coke from the hydrocarbon vapors prior to condensation or fractionation.

Numerous modications of the present invention falling within the spirit of the present invention will occur to those skilled in this art and the invention is to be construed as broadly as the terms of the below claims will permit.

We claim: y l. The method of reducing the viscosity vof a relatively heavy hydrocarbon oil boiling .Within the range of from about 450 F. to about 1400 F. which comprises preheating said hydrocarbon oil, forming a dispersion of petroleum coke in an inert gas, injecting the dispersion of coke into a conned stream of said oil, further heating said oil containing the added coke ina reaction zone to a temperature within the range of from about 750 to about 1400 F. for a period of about 10 seconds, removing the coke from the ,reaction product andv recovering said product. i

2. The process as set forth in claim 1 in which a pressure of about l00lbs. per square inch gauge is maintained on the oil inthe reaction zone.

EDWARD D. REEVES. STEWART H. HULSE.

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