US2702269A

US2702269A - Coking or cracking of oils, pitches, and the like

Info

Publication number: US2702269A
Application number: US192587A
Authority: US
Inventors: Geller Julius
Original assignee: Ruetgerswerke AG
Current assignee: Ruetgers Germany GmbH
Priority date: 1950-10-27
Filing date: 1950-10-27
Publication date: 1955-02-15
Anticipated expiration: 1972-02-15

Description

J. GELLER Feb. 15, 1955 COKING OR CRACKING OF OILS, PITCHES, AND THE LIKE Filed Oct. 27, 1950 /nvenfor 7) aw United States Patent 0 COKING OR CRACKING OF OILS, PIT CHES, AND THE LIKE Julius Geller, Bad Hamburg, vor der Hohe, Germany,

assiguor to Rutgerswerke-Aktiengesellschaft, Frankfurt am Main, Germany Application October 27, 1950, Serial No. 192,587

3 Claims. (Cl. 202-121) For coking petroleum residues, brown and hard coal pitch and the like, comparatively large quantities of thlS initial material are coked in correspondingly spacious devices or ovens. In one known process, the petroleum residues are first of all heated in a tube-type oven and then coked in several parallel-arranged oven chambers constructed of refractory bricks. These chambers are heated from below by means of a large number of burners. Owing to the high content of volatile constituents in the petroleum residues, it is only possible to fill up the oven chambers slowly and gradually, so that the charging time lasts altogether 2 hours. When the filling has been completed, the oven chambers are heated from about 500 or 600 up to about 900 or 1000 C. The coking process itself lasts about 3 hours. Before the expiry of this period, the temperature of the oven is gradually reduced again to about 500.

For emptying the chambers the ovens have doors, and these are lifted after the coking is finished. As the coke is deposited in large adhering pieces in this process, considerable difiiculty is experienced in removing it from the oven. So as to facilitate this removal, strong steel cables are placed in the oven chambers before chargmg these, the said cables being only partly covered by the filling material. On the completion of the coking and the removal of the oven doors, these steel cables are cooled with water and then connected with a winch. Through the forces produced by the winch the closely adhering lump of coke is broken up, and by this means the emptying of the oven chambers becomes possible.

In another known process, ordinary coke ovens are employed such as are usual in the coking of hard coal s. Only minor alterations are made in the construction lIl order to make them suitable for the case under consideration. Although the capacity of these coke ovens is much greater than that of those previously described, the time needed for the actual working is several times that needed in the former instance.

The oven is emptied in the same manner as in normal type ovens, that is, through a pushing or pressing machine which is adapted to travel at the sides close to the ovens and the rod of which presses the coke out of the chambers on the doors being raised.

The known process has the disadvantage that the output is comparatively limited on account of the very long working time. In addition, the arrangement is subjected to considerable variations of temperature owing to the discontinuous operation and the large amounts filled into the chambers each time. These changes in temperature occasion corresponding heat expansions, and these lead after a short period of operating to cracks and leaks in the masonry. The said arrangements thus require constant overhauling and attention. The operating costs are also comparatively high.

A further disadvantage of the said processes is that the pitch coke is deposited in comparatively large, solid pieces. Now the coke is generally required for purposes where it has to be in small pieces, or even in a fine form, and the lumpy coke has therefore in all these cases to be ground fine at considerable expense.

In order to obtain the coke in fine pieces, the initial material has also been injected in a finely distributed condition in the presence of a flame and coked. An adequate fineness of grain is supposed to be obtained here. By injecting the material in nozzles, a great fineness of the grain may certainly be obtained, but this still leads to an uneven end product, because the material is not injected in uniform masses and forms, and does not have a uniform impact.

The purpose of the invention is to obviate the disadvantages of the known processes. For this purpose the material is supplied to the coking space continuously in comparatively small amounts in a form as uniform as possible.

In order to obtain this the material to be coked is supplied to the coking space in the form of drops, streams or jets or fiat sheets of a given thickness. The material is heated and coked in the shortest possible time, so that correspondingly high outputs are possible.

One specially effective form of the new method consists in guiding numerous simultaneous and uniform jets or sheets of material into the coking chamber, to traverse this latter in free drop or fall. Since the coking of the already preheated material ensues in the shortest possible time, the coking chamber does not require to be specially high in order to give the necessary drop. If, in accordance with the invention, the material is injected upwards from below into the coking chamber, the time the material is spending in the chamber is doubled. In such a case, the height of the arrangement can be further limited.

The material will be heated directly or indirectly according to the conditions of working and the properties of the material to be treated. If direct contact of the material, and of the vapours it develops, with the smoke or flue gases, has to be prevented, only indirect heating of the coking material can be employed. In many cases, however, direct heating is possible. In such cases the process may be eifected at high pressure, as the casing which has to bear the pressure can be protected by a sufficiently strong inside insulation from the high working temperatures.

Direct heating of the material becomes specially simple if part of the material itself is burned inside the coking chamber. In general, if the arrangement is adequately insulated, only about 4 to 8% of the material is required in order to carry out the cracking or coking operation at about 1000 to 1200 C.

Should it not be desirable for the working material and the vapours liberated therefrom to come into contact with the smoke or fiue gases, even in such a case direct heating of the arrangement may still take place, only in this event the heating of the arrangement and the coking of the material must alternate regularly with one another. Thus the arrangement is first brought to the requisite working temperature by direct heating, and then the heating is cut off. The material is thereupon supplied to the coking chamber until the temperature of this latter has reached a certain low level; thereupon heating of the apparatus takes place once more, and so on.

As, in the new process, the material is coked in a comparatively finely distributed form, a uniformly finegrained coke is deposited possessing a large surface area. Consequently the coke has to be cooled ofi, on leaving the arrangement, in the absence of air, with steam or cold flue gases, to such a point that it cannot ignite during its subsequent contact with the air.

Should the traversing period provided for the material not be enough to obtain a complete liberation of the volatile constituents, further provision has been made, in accordance with a preferred form of the invention, to subject the depositing coke to a special or additional treatment immediately following. To this end a tunnel kiln can be directly connected on, or it is treated in a collecting hopper in the suspended state, either with superheated steam at approximately 1000? C. or with smoke or flue gases from burners, or by furnace-type burners.

For carrying out the new process, vertical and pref erably cylindrical coking chambers with one or more preferably vertical supply pipes for the material are used. An outlet is also provided for the coke, and also an outlet for the gases liberated, the vapours being in general drawn ofl at the top and the coke at the lower part. Should the vapours still be carrying fine coke particles along with them, it may be an advantage to.

pass the vapours, after their egress from the coking space,

' extent.

lthronghga cyclone, andlto. pass, the separated particles of coke to the;lower coke outlet.

If the material is heated indirectly, the coking chambet is surrounded by a casing spaced evenly and at a comparatively small distancefrom the former, so that an annular'spaceis formed between the two for. thepassage of the heating gases; 'A simple constructional form -of the arrangement isthus possible, providingafree and v unrestrictedheat expansion; 7

In order to supply and lead away. the smoke or flue gases-,collector channels are located both at the upper tween the collector channels and the annular gap for the purpose of equalising the one-sided draught.

These throttle grids. consistof movable constructional elements soas not-to affectthe free movability of the casing with respect toithe coking chamber.

' Ifthearrangement is constructed fora direct heating of the material then only one. collector channel has to-beprovided at the upper or lower end of the coking space for conducting away the gases and liberated vapours. In this case also a throttle grid is provided between the coking chamber andthe collector channel in order to equalise the one-sided draught dnring'the conducting away of the gases and vapours.

As the material passes through the coking chamber in a free fall, the heat transmission by radiation must becorrespondingly high. For this purpose, the walls of the coking chamber are in general heated to over 1000.

,In addition, however, the inside walls of the coking chamber are preferably provided with a ceramic lining, containing admixtures of heavy metal oxides. In this way the radiating capacities of the inside walls are still further enhanced.

V In order to utilise the perceptible heat of the gases and vapours leaving the apparatus, the combustion air, and also the material, are preheated to a considerable In addition to this, further exhaust heat still existing can be used for other purposes.

The enclosed drawing shows in vertical longitudinal cross section an arrangement for cracking or coking with indirect heating of the coking space or chamber 1.

The embodiment consists essentially of a vertical cylinder which is closed at the bottom by meansof a cone, the apex of which is directed downwards. At the top the'cylinder terminates in 'a freely supporting cupola.

The walls of the coking chamber consist of refractory ceramic material on account of the high working temperatures, whichare generally over 1000 C. The material which' islto be coked or cracked passes through a pipe 2 into a space 1, the pipe opening into a' nozzle 3 directed vertically upwards. Through this nozzle the material is injected a considerable distance upwards into thecoking chamber; The degree of breakingup of the material can be adapted to the prevailing conditions.

The cylindrical walls of the coking chamber. l-extend downwards beyond the cone so that an annular chanhel 4 is formed between the cone and the walls; One

or more gas or oil burners 5 are connected to this chanml and eifect the heating of the whole arrangement.

The bottomof the annular channel 45s supported ,by

an iron base plate 6, which in its turn is supported by a number of pillars 7. In this manner the coking chamber can expand freely and unrestrictedly in an upward direction from the base plate 6.

" The coking chamber 1 is surrounded 'by a casing S for guiding the heating gases, this casing being provided with inside insulation 9. At the same time this insulation is so close to the coking chamber [that only acomparatively narrow annular gaplt) exists between v or'burners 5, an even distribution of the smoke gases over the annular gap is secured. In -this way the walls-of the-coking chamber are'sweptin a completely uniformmanner by the gases along the entire circumference and are thus heatedin a completely'uniform manner.

The insulation 9 embraces the" external cylindrical wall surface of the coking chamber 1 at the lower end in the manner of a stufiing box, sothat' the two' parts eanex: pand independently during the heating. The correspondingannular slot between the two' walls is preferably completely sealed in a gas-tight manner by means of asbestos cord or the like. a

As may be seen in the drawing,v the inside lining 9 of thecasing 8 rests upon a base plate 12, which in its turn is supported by'pillars 13. I. In this way the coking chamber and the surrounding casing are supported independently of one another.

The cupola closing the coking chamber at thetop is provided with a centrally :locate'd'br'anch- 1 4' through whichthe vapours and gases that are released during coking or cracking can passoif. r

The gases flowing upwards in the annular gap 10 pass finally into an annular collector channel 15, the bottom gases are'drawn-oif from the gap-10 -uniformly around' the whole circumference. 7

The annular channel 15 isclosed at the top by means of a cover 19, this latter having an inside insulation of suspended brick. The branch 14=provided for the outlet.

of-the vapours is made gas-tight by means of a stuffing box 20 located on the cover- 19, so that'it is impossible for extraneous'air to pass into the'heatinggas system.

A- free expansion of the branch 14 in relationto casing 8 is thus made possible at this point also. 7

The coke dropping in the form of-fine-grains reaches an outletbranch '21 and is carried away by a worm 22,

which is self-sealingagainst the passage-ofgas. Although the'cone that closes the coking chamber atthe bottom is not heated at the lower part, it is nevertheless of advantage to make; the worm of heat-resistant steel or ceramic material.

In order to prevent 'the ignition? of the still glowing coke in the air, itiis first of all drawn off into a cooling 0111131111361, and only then is .it brought into contact'with t e air. a J

For the purposeofiliberating the volatile constituents still retained in the. coke, a calcining or graphiting plant not'shown in the drawing .is provided, which may consist of a tunnel kiln, and in which with uniform heating the volatile constituents are freed. The proceduremay-however be such that the coke accuruing is held suspended the like, comprising ,in combination a vertical, cylindrical. heating chambenat'least one conduit for the introduction into the middle Zone of said chamber, of the material to be treated; said heating chamber having a downwardly tapering lower end part formingan' opening for the-discharge of residual products and-being provided at its upper end part with a tubular outlet for the discharge. of volatile products formed in the heating chamher; a cylindrical-casing provided with a:thermally' insulating layer'on its inner side and surrounding the wall of the heating chamber to form a narrow annular gap therewith, the upper end part of said casingsurrounding the tubular outlet of the heating chamber and forming therewith an annular'collecting channel for heating gases,- said channel having adischarge openingfor used'heating gases, the bottom Wallof :the channel being formed by perforated elements arrangediabove said annular gap; the wan; of the. heating chamber extendingdownward around its tapering 'end portion and forming an annular .second channel'with the latter; said second channel being provided with at least one opening .for burners supplying heating gases; said secondannular channel being connected with. said annular gapby, openings hayingcross' sections of different size in order toequajlize distribution and velocity of the heating gases supplied by said burners, within the annulargap; said elements forming'the bottom wall of the collecting'channel having perforations 4 of different size, in order to' equalizejvelocity of the 'heating gases passing from the annular gap to the collecting channel and to its discharge opening; said heating chamber and said casing provided with an insulating lining, being supported independently from each other and capalllale of thermal expansion independently from each er.

2. A device for coking and cracking oils, pitches and the like, comprising in combination a vertical cylindrical heating chamber; at least one conduit for the introduction into the middle zone of said chamber, of the material to be treated; said heating chamber having a downwardly tapering conical lower end part forming an opening for the discharge of residual products and being provided at its upper end part with a tubular outlet for the discharge of volatile products formed in the heating chamber; a cylindrical casing provided with a thermally insulating layer on its inner surface and surrounding the heating chamber to form a narrow annular gap therewith, the upper end part of said casing surrounding the tubular outlet of the heating chamber and forming therewith an annular collecting channel for heating gases, said channel having a discharge opening for used heating gases, the bottom wall of said channel being formed by perforated bricks loosely arranged at the upper end of said gap; the cylindrical wall of the heating chamber extending downward around its tapering end portion and forming an annular second channel with the latter; said second channel being provided with at least one opening for burners supplying heating gases; said second annular channel being connected with said annular gap by openings having cross-sections of diflferent size in order to equalize distribution and velocity of the heating gases supplied by said burners, within the annular gap; said bricks forming the bottom wall of the collecting channel having perforations of different size in order to equalize velocity of the heating gases passing from the annular gap to the collecting channel and to its discharge opening; said heating chamber and said casing provided with an insulating lining, being supported independently from each other and capable of thermal expansion independently from each other.

3. A device as claimed in claim 1, in which the casing has a ceramic lining containing the oxide of a heavy metal in order to increase the radiating capacity of the lining.

References Cited in the file of this patent UNITED STATES PATENTS 1,648,856 McEwen Nov. 8, 1927 1,797,796 Runge Mar. 24, 1931 1,825,374 Thiele Sept. 29, 1931 1,854,300 Greene et al. Apr. 19, 1932 1,938,596 Karrick Dec. 12, 1933 2,100,762 Becker Nov. 30, 1937 2,224,685 Kahl Dec. 10, 1940 2,393,658 Rueckel Jan. 29, 1946 2,445,328 Keith July 20, 1948 2,456,796 Schutte Dec. 21, 1948 2,527,575 Roetheli Oct. 31, 1950 2,606,144 Leffer Aug. 5, 1952 FOREIGN PATENTS 242,622 Great Britain Mar. 11, 1926 286,404 Great Britain Mar. 8, 1928 216,476 Switzerland Aug. 31, 1941

Claims

1. A DEVICE FOR COKING AND CRACKING OILS, PITCHES AND THE LIKE, COMPRISING IN COMBINATION A VERTICAL, CYLINDRICAL HEATING CHAMBER; AT LEAST ONE CONDUIT FOR THE INTRODUCTION INTO THE MIDDLE ZONE OF SAID CHAMBER, OF THE MATERIAL TO BE TREATED; SAID HEATING CHAMBER HAVING A DOWNWARDLY TAPERING LOWER END PART FORMING AN OPENING FOR THE DISCHARGE OF RESIDUAL PRODUCTS AND BEING PROVIDED AT ITS UPPER END PART WITH A TUBULAR OUTLET FOR THE DISCHARGE OF VOLATILC PRODUCTS FORMED IN THE HEATING CHAMBER; A CYLINDRICAL CASING PROVIDED WITH A THERMALLY INSULATING LAYER ON ITS INNER SIDE AND SURROUNDING THE WALL OF THE HEATING CHAMBER TO FORM A NARROW ANNULAR GAP THEREWITH THE UPPER END PART OF SAID CASING SURROUNDING THE TUBULAR OUTLET OF THE HEATING CHAMBER AND FORMING THEREWITH AN ANNULAR COLLECTING CHANNEL FOR HEATING GASES, SAID CHANNEL HAVING A DISCHARGE OPENING FOR USED HEATING GASES, THE BOTTOM WALL OF THE CHANNEL BEING FORMED BY PERFORATED ELEMENTS ARRANGED ABOVE SAID ANNULAR GAP; THE WALL OF THE HEATING CHAMBER EXTENDING DOWNWARD AROUND ITS TAPERING END PORTION AND FORMING AN ANNULAR SECOND CHANNEL WITH THE LATTER; SAID SECOND CHANNEL BEING PROVIDED WITH AT LEAST ONE OPENING FOR BURNERS SUPPLYING HEATING GASES; SAID SECOND ANNULAR CHANNEL BEING CON-