US2436160A

US2436160A - Cracking of hydrocarbon oils with

Info

Publication number: US2436160A
Authority: US
Priority date: 1943-12-10
Filing date: 1943-12-10
Publication date: 1948-02-17
Anticipated expiration: 1965-02-17

Description

Patented Feb. 17, 1948 4umrrzo sTATEs PATENT orrics essere CBACKING F FINELY DIVIDED CATALYTIC MA nrnaoannoN ons wrm naar nasrsram- NoN- remar.

Forrest H. Blending', Elisabeth, N. J.. assigner to Standard Oil ration of Delaware Develop ment Company, a corpoappueeuen December 1o, 1943, seem no. 513.671 A s chime. (ci. 19e-ss) tion gasoline has been produced by thermal cracking, 'particularly by those processes which operate at high temperatures. In this type of operation the quantity of normally gaseous hydrocarbons formed is high,'and it so happens that the requirements ent time. that is to say, there is a definite need for the olens such as ethylene, propylene, butylene, etc., for these materials may be used to alkylate an isoparailin such as isobutane to form an alkylate, so-called. a very valuable agent useful in the manufacture of 100octane aviation gasoline; In addition, oleflns such as butylene are dehydrogenated butadiene, asubs material in the manufacture of synthetic rubber and rubber substitutes. It has also been shown that highly concentrated aromatic oils can be made by intensive thermal cracking. These fractions have Abeen vitallyv useful in modern aviation gasoline manufacture.

According to my present process, I subject a hydrocarbon oil such as a gas oil to severe cracking conditions in the presence of a solid inert material and I obtain a product which is high in aromatics.- Very desirable constituents are thus available for use as an laviation gasoline.

In a. preferred methodof operating my process, I iniect cold oil directly-into a viiuidized mass of inert refractory and heat the oil to severe-cracking conditionsv in a relatively short period oftime. Ihe may then be quenched after: afs'hort reaction or contact time to prevent undesired side reactions.

The main object oiimy present invention is to produce a high quality gasoline by thermal cracking, of feed stock under conditions such as to produce increased quantities of aromatics.

Another object oi crack a hydrocarbon oil under conditions such as to produce large quantities of olens.

.a third object of my invention is to design a thermal c plant adapted to operate at temperatures as high as' 2000 F. and employing a um of expensive and special alloy steels.

for a number of normally, gaseous hydrocarbons is also great at the presf in large quantities to form A ce which is a valuable raw my invention is to thermally:

Another object of the invention is an operable and feasible process to accomplish severe oil cracking. In connection with this object I desire to emphasize that in normal cracking units fusing coils or drums, coke is formed at comparatively low temperature (around 900 F.) which limits the severity of the operation. This objection can be overcome only by steam cracking or cracking with diluents at very low pressur The addition of steam and use of low pressures necessitate large coils or drums made from highly critical materials.

Other and further objects of my invention will appear from the following more detailed description and claims. Y

' In the accompanying drawing I have shown diagrammatically an apparatus in which a preferred modiflcation of my invention may be carried into effect. f

Referring in detail to the drawing, 1 repre-` sents a reactor lined with brick or other refractory material, which is in the form of a cylindrical vessel with an upper and lower conical section. In reactor I I maintain' a bodv of iiuld- 'ized solid material which does not easily `disintegrate. such as crushed coke, powdered cosi, ground pumice, sand, orany highly refractory non-catalytic material (from the standpoint of catalytic cracking). 'I'he solid material is nely divided and may be in the form of a powder but preferably is in the form of particles or aggregates oi 'appreciable size up to il; inch average particle size. I maintain the solid material in the fluidized state referred to by forcing gases, including oil vapors, upwardly in the vessel at a velocity of from 0.5-15 feet per second. I prefer to use the larger size particles, say at least 1A; inch average size, because thispermits a higher gas or vapor 'velocity in the reactor since the greater the particle size the greater the vapor velocity must be to maintain the solids in fiuidized state. I may discharge steam through line Ill into the reactor under such pressure conditions that lt will now upwardly in conjunction with hydrocarbon vapors, also contained therein, within the limits of velocity indicated. I also inject into the reactor I through line I2 cold (atmospheric temperature) gas oil such as, for instance; an East-,Texas gasoil boiling within the range oi' from 40o-800"` F. and having an A. P. I. gravity of about 25. I may also. however, preheat the oil tov 600 F. or higher before introducing it into the reactor.

The heat necessary vfor the conversion is acquired by the oil from the solid, nuidized material and by preheating. The oil. ot course, under the conditions stated undergoes cracking to form a vapor and coke, coke being deposited on the solid material. The vapors are withdrawn overhead through line II and are quenched, fractionated, condensed and collected in the usual manner. Since, however. the vapors issuing from the bed of solid material in the reactor I are at an extremely high temperature. I prefer to quench them by injecting through line Il a quantity of fluid such as water or steam, whereupon the vapors may be cooled, say, to 700 to 1100 F., in line I5. In other words. I so operate my process that the cil is heated rapidly to a high temperature and permits only a relatively short contact time, or residence time, say of the order of up to 5-10 seconds, preferably below 2 seconds or even one second, because short contact time prevents or suppresses undesired side reactions. Hence, my preferred method of operating is to heat the feed oil rapidly to a high temperature, say, around 1800 F., preferably at a .temperature between about 1200-1500 F., pass the vapors through the fiuidized mass at a high velocity, say, up to feet per second; and quench the vapors as they emerge from the reactor. To prevent carry-over of solid in large quantity with the exit vapors, the particle size of the solid material must be relatively large, viz., of the size previously indicated. From line I5 I pass the vapors through a waste heat boiler I8 where they are further cooled to a temperature of about 250 F. up to 600 F., whereupon they are withdrawn through line I8 and passed into a fractionator ,20. From fractionator normally gaseous hydrocarbons may be withdrawn through line 22, a gasoline fraction withdrawn through line 2E, a fraction boiling within the light gas oil range, say up to 600 F., withdrawn through line 26, and iinally a bottoms fraction is withdrawn through line 28 and recycled to I2. A portion of this latter fraction may be withdrawn continuously from the system through line 30.

Referring back to the reactor I. the solid material which of course accumulates coke in the cracking operation is continuously withdrawn through a drawoii.' pipe 6 carrying a flow control valve 8, and this material is discharged into a mixing device 9 where it is mixed with air or other oxygen containing gas from Il and then conveyed pneumatically via line 32 into a burning or combustion zone 33. In zone 33 secondary air may if necessary be injected through a line 35. and the air or other oxygen-containing gas thus introduced at the high temperatures involved causes combustion of the tarry material or coke deposited on the solid material as a result of the cracking in reactor I. Incombustion chamber 3l the gases and the solids now concurrently upward causing the linear velocity of the gases to be of the order of 20 ft. per second, or higher, if necessary. The suspension of regeneration gas and/or regeneration fumes containing the solid material is withdrawn through line 40 and passed through a plurality of separating devices 41 wherein the solids are separated from the regeneration fumes via lines Il, and the solid .is then conveyed by gravity to a feed hopper 5l from which hopper it may be conveyed by gravity into the reactor I thus completing acycle of operations.

As indicated previously, a good way to operate my process is to lay vdown enough coke in the solid material in reactor I by the cracking that when this coke is burned in chamber I3.

enouiih heat will be absorbed bythe solid material to preheat the oil, to vaporize and superheat the said oil and to supply the endothermic heat. I! desired. extraneous oil or other combustible material may be burned with the formed coke in combustion chamber 33. Furthenheat may be recovered from the hot cracked vapors and employed to preheat the oil in suitable heat exchangers.

While I have described in detail the method ot processing a gas oil, it will be understood that I may inject a heavy oil such as a reduced crude directly into the reaction zone. As indicated. the oil injected need not be at atmospheric temperature but may be preheated somewhat, say to a temperature of 4NI-800 F., but the main bulk of the heat is supplied by contacting the oil with the hot solid material which may have a temperature of 2000-2200 F. and preferably has a temperature of at least l200 F.

I have shown means wherein oil is sprayed into the combustion zone 33 through a line 34, This additional oil is added where insuiiicient coke is laid down on the particles during cracking to supply upon combustion the heat necessary for the process. Also, I may add powdered coal or some other combustible material such as a normally gaseous hydrocarbon or CO, or any other combustible material. Coal or coke may be used as the inert material and added or withdrawn as required. I have shown an upilow" combustion chamber.

Numerous modiiications of my invention may be made by those familiar with this art without departing from the spirit thereof.

I claim:

l. A continuous process for cracking hydrocarbon oils, which comprises providing a mass ci finely divided, non-catalytic, heat resistant material in a reaction zone, maintainingsaid finely divided material in fiuidized condition, injecting an oil to be cracked directly into said mass of fiuidized material thereby causing cracking of said oil, the temperature in said reaction zone being within the range of 1200 to 2200" F., supplying a quenching material immediately above the iluidized mass to reduce the temperature of the products arising therefrom, continuously withdrawing finely divided material containing contaminants deposited thereon as a result of the cracking, conveying the nely divided material directly to a combustion zone, causing the contaminants on the iinely divided material to be consumed by combustion in the combustion zone, withdrawing the finely divided material from the combustion zone and returning it directly and substantially uncooled to the reaction zone for effecting vaporization and cracking of further amounts of oil.

2. A continuous process for cracking hydrocarbons, which comprises providing a mass oi nely divided, heat resistant, non-catalytic material in a reaction zone, maintaining said mass in fluidized condition, injecting an oil to be cracked directly into the fluidized mass in said zone in at least partly liquid condition as it enters said zone, the temperature in said reaction zone being within the range of 1200 to 2200 F., cracking the oil in said zone in contact with the nuidized mass which is at a vaporizing and cracking temperature, supplying a quenching material to the reaction zone above the uidized mass to reduce the temperature of the lproducts arising therefrom, continuously withdrawing finely divided material containing contaminants deposited thereon as a result of the cracking, conveying the finely divided material directly to a combustion zone, causing the contaminants on the finely divided material to be consumed by combustion in the combustion zone, withdrawing the finely divided material from the combustion zone, and returning it directly and substantialiy uncooled to the react-ion zone for eilecting vaporization and cracking of further amounts of oil.

3. A continuous process for treating hydrocarbons by intensive thermal cracking to produce increased quantities of aromatica and normally gaseous olens which comprises providing a mass of finely divided, heat resistant, non-catalytic material in a reaction zone. maintaining said mass in iiuidized condition, injecting an oil to be cracked directly into the fiuidized mass in said zone in at least partly liquid condition as it enters said zone, cracking the oil in said zone for a period oi' timeless than about 10 seconds in contact with the -fiuidized mass which is at a vaporizing and cracking temperature, supply ing a quenching material to reduce the temperature of the products arising from the reaction 25 zone. continuously withdrawing iinely divided material containing contaminants deposited thereon as a result of the cracking, conveying the tinely divided material directly to a combustion zone, causing the contaminants on the 30 iinely divided material to beconsumed by combustion in the combustion zone, withdrawing the iinely divided material from the combustion zone, and returning it directly and substantially uncooled and at a temperature within the range of 1200 to 2200 F. to the reaction zone for eliecting vaporization and cracking oi' further amounts of oil.

FORREST H. BLANDING.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED VSTATES PATENTS OTHER REFERENCES Sachanen. "Conversion of Petroleum. 1940, Reinhold Pub. Co., New York, page 144. (Copy in Division 31.)