US1307724A - cojtst - Google Patents

Description

JA. 7 APPARATUS FOR CRACKING HYDROCARBONS.

J. W. COAST APPLICATION FI1.'ED OCT. 6.1917

latonfed June 24, 1919.

, A m N Tao i PATENT mom: w. sense, an, or TULSA, oKLAnioma, ASSIGNOR TO THE rnocnss comm, or,

-msayox anoma, A conronarron or MAnYLAnD.

AZBPARATUS non; onacmne rrrnnooamaons.

To all whom it may concern; v

Be it known that I, JOHN 'W.;-Coasr,:.-;Ir., 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 Apparatus for Cracking Hydrocarbons, of which the following is afull, clear, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

This invention relates to improvements in apparatus for cracking hydrocarbons, and

more particularly to a structure involving the use of a fire-heatedcracking still Wherein a body of hydrocarbon oil is confined under pressure. Y

' While the oil is undergoing distillation under high pressure and, at a high temperaordinary practice it is necessary to increase the temperature of the still bottom as the cracking. operation progresses, so as to maintain the oil at the necessary high temperature. 'As a consequence, the still bottom is liable to be overheated and become red hot, and in this event some immediate steps must be taken to avoid a rupture at the overheated portion of the still. The still may be cooledand the operation discontinued for the pprpose of removing the residue, or the crac lower temperature. steps are very undesirable.

The accumulation of coke-forming matter body of insulating matter, and the life of the still is decreased by exposure to high temperatures. However, the greatest loss is ng operation can be continued at a Obviously, both of these Specification of Letters Patent. Patented J fine 24 1919;

Application ale-a 0ct9ber 6, 1917. Serial No. 195,066.

uteto the fact that the necessary high pres- My objects are to avoid the danger and heat losses which have resulted from the presence of coke-forming matter in large cracking stills; and to crack and distil the oil very rapidly, thus increasing the capacity of the still. However, a most important advantage lies in the greatly increased yield of low boiling point hydrocarbons, which I obtain by maintaining the oil at the necessary high pressure and temperature, until it no longer responds readily to the cracking treatment.

In the preferred form of the invention, all of the foregoing advantages are obtained by confining a body of hydrocarbon oil in a large horizontal cylindrical fire-heated cracking still, the arcuate bottom of the still being exposed to the fire; maintaining the contents of the still at a high pressure and at a high temperature, and at the same time continually sweeping coke-forming matter from one end of the still to the other. One end of the still bottom is protected from the fire and the coke-forming matter is swept along the still bottom and permitted to aceumulate at said protected end. Therefore, the heat is transmittedfreely from the fire heated still bottom to the oil, and the high temperature can be maintained without-oven heating the still. In addition to the advantage of greatly increasing the yield of low boiling point fractions. the cracking operation can be carried on continuously for a considerable period of time, by introducing a fresh chargeinto the still without removing the residue.

Figural is a diagrammatical view of a cracking apparatus constructed in accord ance with my invention.

Fig. II is an enlarged fragmentary longi tudinal section of the still.

Fig. III is an enlarged-transverse section of the still.

The apparatus shown to illustrate the invention comprises a large horizontal cylindrical cracking still 1, arranged above a heating chamber 2 and connected, by means of a vapor pipe 3, to an air cooled reflux condenser 4. 5 designates a vapor pipe leading from the reflux condenser to a water cooled condensing coil 6 from which the low boiling point product is recovered.

The apparatus herein shown is particularly adapted for usein cracking high boiling point products of distillation such, for

example, as distillates or residues resulting from the distillation of crude petroleum. The oil to be treated may be introduced into the'still inany suitable manner, andai'iy desired'pressure may be obtained by regulating a valve 7 preferably arranged in the vapor pipe'5. The pressure in the still is greater than three atmospheres, preferably about 80 pounds per square inch, and the temperature of the contents of the still preferably ranges from about 600 F. to 800 F.

ing the yield of low boiling point fractions,

the coke-forming matter is constantly swept to one of the protected end portions of the still bottom.

The continuous, flexible, endless sweeping device comprises a pair of endless sprocket chains 9, arranged longitudinallyof the still and fitted to sprocket wheels 10 near the ends of the still. I The sprocket wheels 10 support the endless chains 9. Arcuate bars 11, arranged transversely of the still, are

connected to the pair of sprocket chains 9.

12 designates. scraper blades conforming to the configuration of the arcuate still bottom, and provided with fingers 13 which extend through guides or bearings 14 on the arcuate bars 11. The fingers 13 are rigidly secured to the blades 12 and slidably mounted in the bearings 14. Pins 15, passing through the fingers 13, prevent the latter from accidentally dropping out of the bearings 14. Each arcuate scraper carrying bar 11 is preferably provided with a series of the blades 12,.as shown in Fig. III.

The means for actuating he endless sweeping device comprises a power shaft 16 passing through a stiifling box 17 at one end of the still, and provided with-an operating Wheel 18 (Fig. I) at the exterior of the still. A worm 19, at the inner end of the power shaft16 meshes with a wheel 20 on the shaft 2l,to.which two of the sprocket,

the endless sweeping device in a continuous endless course, as indicated by arrows in Fig. II. The lower portion of the sweeping device travels along the fire heated bottom of the still, in one direction only,-thereby constantly sweeping coke-forming matter to a protected end-portion of the still bottom, immediately above one of the walls 8. The coke-forming matter will, therefore, accumulate at a part of the still not exposed directly to the fire, and it will not in any way interfere with the transmission of heat from the fire tothe oil. The cracking operation can, therefore, be continued long enough to obtain a greatly increased yield from the heavy oil, and since the danger of overheating the still is almost entirely eliminated, a very hot fire can be maintained and the oil can be distilled very rapidly.

23 designates coke-receiving chute arranged within thestill and surrounded by the endless sweeping device. This chute is so inclined that the coke-forming matter falling thereon will be'discharged at the protected end portion of the still, where the main-body of cokeis permitted to accumulate. An arcuate brush 24 is secured to the upper portion of the still for the purpose of removing coke-forming matter from the scrapers 12. Thebrush 24 extends into the path of the scrapers 12, so as to remove the coke-forming matter from the scraping edges. After forcing coke-forming matter to a protected end of the still, the scrapers move upwardly as indicated in Fig. II, therefore, movinghorizontally to the opposite end of the still. and then downwardly to the still bottom. The coke-forming matter dropping from the scrapers at the upper portion of the still,falls onto the chute 23.

I claim:

1. In an apparatus for cracking hydrocarbons, a horizontalcylindrical fire-heated cracking still, a large area of the bottom of the still being exposed to the fire and one end portion of said bottom being protected from the fire, a continuous endless sweeping device mounted in said still and engaging the bottom thereof, means for transmitting power to said sweeping device so as to sweep coke-forming matter to the protected end of the still, and a chute surrounded by said endless sweeping device, said chute being inclined to direct coke-forming matter to said protected end portion of the still 2. In an apparatus for cracking hydrocarbons,.a fire-heated cracking still, a continuous endless sweeping device mounted in said still and engaging the bottom thereof,

means for transmitting power to said continuous endless sweeping device, and a cokereceiving device surrounded by said endless sweeping device to receive the coke-forming matter passing from the upper portion of the sweeping device.

3. In an apparatus for cracking hydrocar' hons, a fire-heated cracking still, a continu ous endless sweeping device mounted in said still and engaging the bottom thereof, means for transmitting power to said continuous endless sweeping device, means for removing coke-forming matter from the upper portion of said endless sweeping device, and a coke-receiving device surrounded by said endless sweeping device to receive the cokeforming matter passing from the upper portion of the sweeping device.

4. In an apparatus for cracking hydrocarbons, a fire-heated cracking still, a continu ous endless sweeping device mounted in said still and engaging the *bottom thereof, means for transmitting power to said continuous endless sweeping device, and a "brush secured in said still above said sweeping device to remove coke-forming matter therefrom. V

In testimony that I claim-the foregoing I hereunto aflix my signature. 1

f JOHN W. COAST, JR.

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