US2778781A - Process for the continuous coking of hydrocarbons - Google Patents

Description

Jain. 22, 1957 A. D. SMITH PROCESS FOR THE CONTINUOUS COKING OF' HYDROCARBONS Filed May 25, 1953 2 sheets-sheet 1 Jan- 22, 1957 A. D. SMITH 2,778,781

PROCESS FOR THE CONTINUOUS COKING OF HYDROCARBONS Filed May 25, 1953 2 Sheets-Sheet 2 United States Patent icc v PRUCESS FOR-T HE-CONTINUOUS COKING OF. HYDROCARBONS!v Arthur. 1).Sn1itl1,` Chicago, Ill., assigner to Jenkins PetroleurnProcessVK Company, Chicago, lll., a corporationof The invention relates `more specifically to the coking of relatively 4heavy;- petroleum hydrocarbons, and parti cularly,to` a jmethod and apparatus for preventing .agglomeration, during 'coking of such. hydrocarbons, of large massesof carbon preventive of thecontinuous .production.y of coke particles of a pre-determined, classified size.A

. Continuous coking lof residual petroleum hydrocarbons has already been proposed wherein acirculating mass of heated, relatively small coke particles is contacted in a coking drum with a stream of partially or completely vaporized hydrocarbon oil; the operation being conducted at such temperature and under such time factor as to effect during pyrolysis of the hydrocarbon employed a progressive accretion of carbon on the surface of the coke particles which, when a pre-determined size is attained, are continuously withdrawn from the system. A downward gravity flow of the coke particles is taught as a preventive of agglomeration of coke masses in `one process, and in another mechanical agitation in the coking chamber is recited; but a slight interruption of gravity ow can cause suicient agglomeration to impede or stop the continuous discharge of product coke, and there is some tendency for agglomerates to build up on a conventional mechanical agitation means.

In the present invention such agglomeration is prevented and continuous discharge of product coke assured by installing in a conventional coking drum a revolving tubular means supplied with steam under such pressure, that escaping through small orifices provided in said means, it progressively impinges on and breaks down any incipient agglomerate formation.

In order that the invention may be better understood, reference is made to the accompanying drawings where Fig. 1 represents in fragmentary vertical elevation a conventional coking drum in which is installed the above described steam-supplied, revolving means. Fig. 2 depicts an enlarged vertical sectional view of such tubular means disposed in a fragmentary elevation of a said coking drum; While Fig. 3 shows a cross-sectional view taken on the line III-III of Fig. l.

Referring specifically to Fig. l: in operative practice the conventional coking drum 10, previously substantially filled with a bed of relatively small coke particles is continuously supplied with a stream of attrited coke fines through the line 11, and with hydrocarbon oil to be coked through the line 12; it being understood these raw materials and the coking chamber respectively obtain at suitable coking temperatures according to practices well known in the art. Vapors evolved during pyrolysis of the oil escape through the line 13 to conventional fractionating and cooling means (not shown) from which light oil fractions and gas are recovered and separated in a well known manner. Coke particles, accreted to a predetermined size through progressive deposition of carbon derived from the pyrolysis of said oil, descend from the coking drum together with attrited coke fines through valve 14 to a heating zone (not shown). From the latter,

2,7 78,781 Patented-,Jens 232-19%? thev .coke particles of pre-determined size ,are continuously, withdrawnfromahesystem, whilegthe cokenes are re-v. turnedto the coking. drum`.through.line .11..hysl the agency, of .a gas lift'or .other well-known means,(not.shown),. Formation of `agglomerates of cokepreventive of the continuity of vdischarge of said.coke.particles, is inhibited by thecontinuous rotative` passage .ofa curtain of steam through said cokeVbedduring saidt'pyrolysis; such steam. curtain rbeing .dischargedfrom Athe .rotatingtubular means 15... Thelatter comprises aperforated, steam.main,15` With connecting,v perforated. DQshaped branch the said: main. being vertically. positioned and. concentrically mounted Withinthecokingdrum. The lower portion lof, such steam main is supported by the sleeve bearing 16, andthe `upper portion byYtheTOl-cooled thrust type ballbearing117 (detailejdin Fig', 2).,- The steam main .passes externally Afrom thecokingfdr'uin through the oil-cooled stalling box 18 suppliedlwith cooling oilV through pipe 19;v the vvmain thencepas'sing through the stuffing box 20 by which steam is externallysupplied "by pipe 21 `Vtosaid main.: At theuppery end of the steam main is mounted the, bevel l'gear 221,7v actuatedy by l, engaging gear l22' and driven by'motor 23,'su`pported bybase 24; it beingvunderstood any suitable power drive may be substituted for the motor shown including a speed reducing means.

Referring specifically to Fig. 2; it is to be understood cooling oil supplied through line 19 enters under sufficient pressure to fill the annular chamber 13 and overcome the existing pressure in the coking drum; the oil after indirectly cooling the packing 25 passing around the ball race of the thrust bearing and into the coking drum, thus forming a small portion of the coking charge.

Steam enters the annular chamber 20 through the pipe 21 and thence into the steam main 15 through a series of holes 26 drilled in the wall of the former; the packing gland 27 and packing 28 maintaining a seal as the steam main revolves. The latter is perforated on one side with a series of small aligned apertures 29, and the branch 15 with correspondingly aligned apertures on the opposing side to the main 15", so that issuing jets of steam from these members will mutually-impinge and form a curtain of steam substantially within the plane bounded by the perimeter of said revolving means 15. Similar aligned apertures in branch 15" on the side adjacent the inner wall yof the coking drum permit a discharge of steam preventive of agglomerato adhesions on said wall.

It is a feature of the invention to employ as small apertures as possible in combination with high pressure steam and a speed of rotation of the tubular means 15 only suflicient to prevent formation of agglomerates. Such combination spells for a minimum consumption of steam and a proportionate inhibition of any undesirable water-gas reaction between the released steam and carbon. In a coking drum of relatively small diameter the steam consumption may be further reduced by omitting the branch 15". The steam curtain will then be generated entirely by the steam main 15', but as before, will progressively and recurrently sweep through the entire coke bed as the main revolves.

To prevent any tendency of clogging, the apertures 29 are perforated at a downward angle to the perpendicular; such angle being approximately in the general direction ow of the coke bed and thus assisting in the circulation.

The process is not limited to any specilic temperature or pressure provided these fall within the limits employed in the coking pyrolysis of hydrocarbon oil; nor the apparatus to the particular form or relational size herein shown which illustrates one embodiment for carrying out the process. What I claim as new and desire to protect by Letters Patent is:

1. A continuous process for producing coke pellets of predetermined size from the pyrolysis of hydrocarbon oil which comprises subjecting coke pellets of relatively small size obtaining as a flowing bed to progressive accretion of carbon derived from the concurrent pyrolysis of contacting said hydrocarbon oil, continuously withdrawing said coke pellets from further carbon accretion as said predetermined size is attained, and concurrently during said carbon accretion and said withdrawing continuously passing a rotating curtain of steam through a relatively small portion of said bed per unit of contact time.

2. A continuons process for preventing agglomeration of individual coke particles during carbon accretion thereon into masses exceeding a pre-determined coke particle size which comprises progressively and recurrently passing a rotating curtain of steam between a relatively small area of said coke particles per unit of contact time during the period of said carbon accretion and as said particles are withdrawn from the system on attainment of said predetermined size.

3. In a process where relatively small coke particles obtaining as a 'owing bed are increased to a pre-determined size through progressive accretion of carbon derived from the concurrent pyrolysis of a contacting hydrocarbon oil, the method of preventing aggl'omerates of said coke particles exceeding said pre-determined size which comprises continuously passing a rotating curtain of steam obtaining in parallel jets through said bed during said accretion of carbon and as said coke particles are withdrawn from the system on attainment of said predetermined size.

4. In a process according to claim 3, the method of employing a minimum quantity of steam to prevent formation of said agglomerates which includes continuously discharging a rotating curtain comprised of parallel jets of said steam and respectively rotating the plane of said jets at such speed and maintaining said steam under such pressure as to satisfy the minimum requirements necessary to inhibit formation of said agglomerates.

5. In a process according to claim 4; wherein said parallel jets of steam are so released as to mutually impinge.

6. In a process according to claim 3; wherein said parallel jets lie in a plane at right angles to said ilowing bed of coke particles.

References Cited in the le of this patent UNITED STATES PATENTS 847,676 Mackethan Mar. 19, 1907 1,276,866 Boyle Aug. 27, 1918 1,614,220 Wendel Jan. 11, 1927 1,656,107 Fairhall Ian. 10, 1928 2,339,932 Kuhl Jan. 25, 1944 2,364,492 Tuttle Dec. 5, 1944

Claims (1)

1. A CONTINUOUS PROCESS FOR PRODUCING COKE PELLETS OF PREDETERMINED SIZE FROM THE PYROLYSIS OF HYDROCARBON OIL WHICH COMPRISES SUBJECTING COKE PELLEYS OF RELATIVELY SMALL SIZE OBTAINING AS A FLOWING BED TO PROGRESSIVE ACCRETION OF CARBON DERIVED FROM THE CONCURRENT PYROLYSIS OF CONTRACTING SAID HYDROCARBON OIL, CONTINUOUS WITHDRAWING SAID COKE PELLETS FROM FURTHER CARBON ACCRERION AS SAID PREDETERRMINED SIZE IS ATTAINED, AND CONCURRENTLY DURING SAID CARBON ACCRETION AND SAID WITHDRAWING CONTINUOUSLY PASSIN A ROTATING CURTAIN OF STEAM THROUGH A RELATIVE SMALL PORTION OF SAID BED UNIT OF CONTACT TIME

Images