US1348265A - Art of cracking hydrocarbons - Google Patents

Description

ART OF CRACKING H'YDROCARBONS.

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

J. W. COAST Patented Aug. 3, 1920.

- UNITED STATES PATENT orFicE.

JOHN W. COAST, JR., OF TULSA, OKLAHOMA, ASS IGNOR TO THE PROCESS COMFAIIY, A

CORPORATION OF MARYLAND.

. m or CRACKING 'nYniaocAiiiioi rs.

Application filed JlI-arch 22, 1917, ser al No. 156,646.

0 all whom it may concern:

Be it known that I, J 0111 1 W. COAST, Jr., a citizen of-the United States of America, a resident of Tulsa, in the county of Tulsa, State-of Oklahoma, have invented certain new and useful Improvements in the Art of Cracking Hydrocarbons, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to improvements in the art of cracking hydrocarbons, and more particularly to a method of protecting stills from the injurious effects of coke or tarry,

-ally drop to 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 reflux condensate and partly by other fractions which do not vaporize in the still. It prevents the free transmission ofheat from the still bottom to the liquid contents of the still, and,

when a sufiicient quantity has been accumulated, the still bottom becomes red hot. Some immediate steps must then be taken to avoid 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 is maintained at a high temperature and under a high'pressure, thus rendering the cracking operation quite dangerous. p

The main ObJGCt of 'my invention is to prevent a large body-of the" coke, or tarry coke-formingsubstances, from accumulating in a singlepill ata point transmitted to the still; In the preferred form of the invention, this is accomplished by condensingfthe'high boiling point frac;

tions and conducting such condensate to a point Where it Will not be subjected directly to the intense heat at the still bottom. The relatively heavy coke-forming fractions are Specification of Letters Patent.

Where the heat is Renewed June 14,1920. Serial no, 389,007.

prevented from circulating to the hottest Patented Aug. 3, 192,0.

part of the still, the lighter fractions of the reflux condensate being permitted to circulate freely in the liquid contents of the still. I thuseffect a separation of the lighter hydrocarbons from the coke forming matter in the reflux 'condensatepermitting the lighter hydrocarbons to be re-vaporized and retaining the coke at apoint Where it will not interfere withthe transmission of heat through the still bottom.

Figure I is a diagrammatic View of 4 a crackingapparatus adapted for use in carrying out my'method.

F 1g. II is a transverse-section of the still taken approximately on the line IIII,

Fig. I.

he still 1, arranged above a heating chamber 2, is connected by means of an air cooled 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 the low boiling-point product is recovered. Thecondensing coil 6. 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 vaper pipe 3 constitutes a reflux condenser, and it is inclined to allow v the-condensate to flow backwardly to the still.

The apparatus I have shown 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 contentsof the still preferably ranges from about 600 F. to 800 F. Heat generated in the heating chamber 2 is trans- Initted directly through the still bottom to boilin point vapors passing from the liquid flow t rough 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 condensed in the vapor pipe 3 or in the condenser 4, such fractions being returned either through the the liquid contents of the still. The low vapor pipe 3 or return pipe 8. This reflux condensate includes a large percentage of heavy coke-forming fractions commingled with lighter fractions,'w hich may bei'rediS- tilled toform-part of the low boiling point product.

- In the preferred form of the invention the end portions of the still bottom are seated upon theJWalls 10 of the heating chamber, and these Walls protect said end portions from the intense heat of the'heating chamber. The heat is transmitted directly through the middle portion ofthe still bottom, and the protected end portions of the still are maintainedin a relatively cool conconductors' 12' lead from 1 dition. -,Diverging v a funnel 1,3 to coke pockets 14 at the ends of the still bottom. The funnel 13 lies directly below reflux condensate ferably arranged on positively the heat is transmitted tothe still. The coke is thus trapped and confined on the tected' end portions of the still bottom, where it will not interfere withzthe transstill; The relatively light fractions of the reflux condensate circulate freely from the coke pockets 14 and. .commingle with the liquid in the still. The co ke in the pockets ing such hydrocarbons the vapor domeiat the upper portion of the still, Where it will receive the discharged from the pipes '3 and 8. Dams, or obstructions, '15 are prethe still bottom to I prevent thev heavy coke-forming fractions from reaching the points at which still under pressure,

liquid. contents of still bottom, prov cool end portions, mission of heat tothe liquid contents of the leis-not materially agitated by the circulationof the liquid in the still, and owing to its weight-it does not tend to float or rise in the lighterliquid- The coke pockets are preferably formedv belowthe surface of the liquid in the still so as to permit the relatively light fractions to circulate from the coke, and the conductors l2'are preferably'submerged the hot liquid-so that the returning condensate will 'be heated before it reaches the coke pockets. Iclaim: v

In the art of cracking petroleum hydro-- carbons, the method which comprises confinting heat directly to the middle portion of the'still bottom, maintaining the. end portions of thestill bottomin a relatively cool condition, maintaining the contents of the conducting vapor from the still to a main condenser, also condensing the high boiling point fractions and' conducting such condensate through the on the relatively cool end portions of the preventing the relatively heavy coke-forming fractions of said condensate from circulatihg away from said relatively and permitting the lighter fractions of said condensate-to circulatefreely in the contents of the still.

In testimon that I claim the foregoing I hereunto a x m signature. I a JgHN W. COAST, In.

in a still, transmitthe still anddepositing it

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