US1348264A - Apparatus for cracking hydrocarbons - Google Patents

Description

J. W. COAST, JR.

APPARATUS FOR CRACKING HYDROCARBONS.

APPLICATION FILED MAR. 22, 1917. RENEWED JUNE 14, 1920.

1,348,264:. e ted Aug 3, 1920.

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'UNITED STATES PATENT OFFICE.

JOHN W. COAST, JR, OF TULSA, OKLAHOMA, ASSIG-NOR TO THE PROCESS COMPANY, A CORPORATION OF MARYLAND.

APPARATUS FOR CRACKING HYDROCARBONS.

Specification of Letters Patent.

Patented Aug. 3, 1920.

Application filed March 22, 1917. Serial No. 156,645. Renewed June 14, 1920. Serial No. 389,006.

To all whom it may concern Be it known that I, JOHN W. Co s'r, Jr., a citizen of the United States of America, a resident of Tulsa in the county of Tulsa,

State of Oklahoma, have inventedcertainnew and useful Im )rovements in Apparatus for Cracking I ydrocarbons, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing, forming a part of this specification. I

My invention relates to improvements in apparatus for cracking hydrocarbons, and more particularly to a means for protecting stills from the injurious eflects of coke or tarry coke-forming substances.

The ordinary cracking still for treating high boiling point petroleum products is provided with means for condensing and returning heavy fractions for further treatment in the still. This reflux condensate comprises relatively light fractions, which, by repeated distillation, may be converted into the desired low boiling point product. However, it also includes a large percentage of heavy coke-forming fractions which usually dropto the bottom of the still and accumulate thereon at points where the still is subjected directly to the action of the intense heat. This coke or carbon is produced partly by heavy fractions in the refiux condensate and partly by other fractions which do not vaporize in the still. it prevents the free transmissionof heat from the still bottom to the liquid contents of the still, and when a suflicient quantity has accumulated, the still bottom becomes red hot. Some immediate steps must then be taken toavoid a rupture at the overheated portion of the still. In actual practice, the coke accumulates on the hot still bottom while the oil in the still ismaintained at a high temperature and under a high pressure, thus rendering the craclzing operation quite dangerous.

The main object of my invention is to prevent a large body of the coke, or tarry. coke--forniing substances, from accumulating in a single pile at a point where the heat is transmitted to the still. In the pro ferred form of the invention, this is ac complished by condensing the high boiling point fractions and conducting such condensate to point where it will not be subjected directly to the intense heat at the liquid contentsof the still.

Fig. II is a transverse section of the'still taken approximately on the line II-II, Fig. I.

The still 1, arranged above a heating chamber 2, is connected by means of an aircooled vapor pipe 3 to a reflux condenser 4. 5 designates a vapor pipe leading from the reflux condenser to a main condensing coil 6 from which low boiling point product is recovered. The condensing coil. G'is preferably arranged in a water tank 7. 8 designates a return pipe for conducting reflux condensate from the condenser 4 to the still. The air-cooled vapor pipe 3 constitutes a reflux condenser, and it is inclined to allow the condensate to iiow backwardly to the still.

The apparatus I have Sl'iOWEl is particularly adapted for use-in cracking high boiling point products of distillation, such for example, as the distillates or residues resulting from the distillation of crude petroleum. The substances to be treated are introduced into the still in any suitable manner, and any desired pressure may be obtained by regulating a valve 9, preferably located in the vapor pipe 5. The pressure in the still is preferably greater than 50 pounds per square inch, and the temperature of the contents of the still preferably ranges from about 600 F. to 800 F. Heat generated in "the heating chamber 2 is transmitted di-- rectly' through the still bottom to the liquid contents of the still. The low boiling point vapors passing from the liquid flow through the vapor pipe 3 and reflux condenser 4; to. the pipe 5, leading to the main condenser 6. The relatively high boiling point fractions are condense in the vapor pipe 3 or in the condenser 4, such fractions being returned either through the inclined vapor pipe 3 or return pipe '8. This reflux condensate includes a large percentage of heavy cokeforming fractions commingled with lighter fractions, which may be redistilled to form part of the low boiling point product.

In the preferred form of the invention the end portions of the still bottom are seated upon the walls 10 of the heating chamber, and these walls protect said end portions from the intense heat of the heating chain-- her. The heat is transmitted directly through the middle portlonof the stillbottom, and :the protected end portions of the still are maintained in 'a relatively cool condition. Divergin' con'ductors'12 lead from a'furmel '13 to 06 e oekets 14 .at the endsv vthe still bottom, where it will not interfere with the transmission of heat to the liquid contents of the still. fractionsof the reflux condensate circulate freely from the coke pockets H and comm-ihgle with the liquid in the still. The coke in the pockets 14 is notmaterially agitated by the circulation of the liquid in the still,

The coke is thus-trapped. and

The relatively light.

and owingto its Weight it does not tend to float or rise in the lighter liquid.

The coke pockets are preferably formed below the surface of the liquid in the still so as to permit the relatively light fractions to circulate *from the coke, and the conductors 12 are preferably submerged in the hot liquid so that the returning condensate wiil be heated before it reaches the coke pockets.

.tom and one end portion of said bottom being protected from the direct action of the heat of the heating-chamber, means 'for conducting reflux condensate into the still, and a conductor 'for directing 'such reflux condensate to the protected end portion of the still bottom.

2. In an apparatus for cracking petroleum hydrocarbons,-a pressure still provided with a heating chamber and a condenser, said heating chamber being below the still bot tom and one end portion of-said bottom being protected fromthe direct action of the heat of the heating chamber, a dam arranged within the stilland associated Wlth said protected portion of said bottom to form a coke trap, a reflux condenser, and means for conducting reflux condensate from said reflux condenser to said coke trap.

In testimony that I claim the foregoing I hereunto ailix my signature.

. JOHN W. coas'r, as.

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