US1929408A - Coking of agglomerates - Google Patents

Description

Oct. 10, 1933.` E. H. BUNCE ,929,408

COKING OF AGGLOMERATES Filed Sept. ll, 1929 2 Sheets-Sheet l INVENTOR @LW ,mlldmzw M ATTORN EYS Oct. 10, 1933. E. H. BUNCE COING oF AGGLOMERATES 2 Sheets-Sheet 2 Filed Sept. 11, 1929 nui@ a .mm m@ Mm mmm,

Patented Oct. 10, 1933 UNITED STATES 1,929,408 COKING 0F AGGLoMERATEs Earl H. Bunce, Palmerton, Pa., assignor to The New Jersey Zinc Company, New York, N. Y., a corporation of New Jersey Application September 11, 1929 Serial No. 391,825

5 Claims.

This invention relates to the coking of agglomerates containing a coking agent, and has for its object the provision of an improved methodof coking such agglomerates. The invention is particularly applicable to the coking of agglomerates of metalliferous material and an appropriate coking agent, such, for example, as agglomerates of mixed zinciferous and carbonaceous materials.

The improved coking method of the invention involves heating of the agglomeratesto the req'uired coking temperature by passing a gaseous heating medium transversely through and in direct contact with an appropriately supported shallow body of agglomerates. aspects, the invention involves progressively advancing the body or column of agglomerates through an appropriate coking chamber and passing the heating gas through the body or column of agglomerates in a direction approximately transverse to the direction of travel of the agglomerates through the chamber. Another feature of the invention involves the provision of an upright or vertically disposed coking chamber through which the heating gas is transversely passed. Where the agglomerates are progressively advanced through the coking chamber, appropriate devices must be provided for charging green agglomerates to and discharging coked agglomerates from the chamber, and with such a practice the invention contemplates the provision of suction on .both the charging and discharging devices to inhibit the flow into the active coking zone of the chamber of any oxidizing gas resulting from the entrance of air through either the charging or discharging device.

The novel features of the invention will be best understood from the following description taken in conjunction with the accompanying drawings, in which Fig. 1 is a sectional elevation of a coking apparatus adapted for a practice of the invention;

Fig. 2 is across section of the apparatus of Fig. 1 on the section line 2-2;

Fig. 3 is 'a sectional elevation of a modied construction oi coking chamber in an apparatus of the type shown inl Fig. 1, and 1 Fig. 4 is a plan view of one of the slotted tiles used in the construction of the coking chamber of Fig. 3.

Referring to Figs. l and 2 of the drawings, the apparatus comprises a brickwork structure 5, of oval horizontal section, having a gas inlet flue 6 and a gas outlet flue '7. Clean-out openings 20 are provided in the curved ends of the structure 5. A relatively narrow coking chamber 8 is built In one of its (ci. 2oz-15) meable to the passage therethrough of gas in considerable volume. This permeability is preferably provided by uniformly distributed openings or slots in each side wall.

In the coking chamber illustrated in Figs. 1 and 2 of the drawings, the vertical side wall 12 is built up of superposed tiles or plates hav ing uniformly distributed slots. These tiles may be made of refractorymaterial, such as silicon carbide alone or mixed with clay, or of temperature-resistant metal alloys, such as alloys of iron, chromium and nickel. The inclined wall is 13 is built up of louvers positioned so that the gas streams leaving the coking chamber are directed upwardly into the gas-exiting chamber 10. This louver construction minimizes the possibility of dust and broken pieces of agglomerates lodging in and choking the openings on the gas-exit side of the coking chamber.

In the coking chamber illustrated in Figs. 3 and 4 of the drawings, the two gas permeable side walls are of similar construction and are built up of removable alloy plates 14 having distributed slots or openings 15. The alloy plates are held in position by spaced cross beams 16 having their ends appropriately suported in the brickwork structure 5 of the apparatus. The inner faces of the beams 16 have longitudinally grooved heads 1'7 in which the lugs 18 and 19 of the plates are engaged. The shorter lug 18 rests on the bottom of` the lower of the engaging grooves, while the longer lug 19 extends only a short way into the upper engaging groove. By raising any plate, its lower lug 18 can be disengaged from its groove and the plate removed and a new plate inserted in its place without disturbing any other plate in the wall.

The upper. end of the coking chamber passin through the roof of the structure 5 has a water jacket 21. A charging extension or hopper 22 provided with a swinging gate 23 is mounted e above the water jacket. A pipe 24 connects the extension 22 with the gas-exiting chamber 10.

A `discharging device consisting of an inclined chute 25 and. a rotatably mounted cylinder 26 is operatively associated with the lower end of the coking chamber 8. The lower end of the chute is closed by a pivotally mounted gate 27 biased to its closed position by a counterweight 28. A pipe.29 connects the lower end of the chute with the gas-exiting chamber 10.

When the apparatus is in operation, the coking chamber 8 is lled with agglomerates undergoing coking.l Periodically, an appropriate amount of coked agglomerates is withdrawn from the chamber by opening the gate 27 and rotating the cylinder 26, and simultaneously a corresponding amount of fresh agglomerates is introduced into the hopper 22. The coking chamber is thereby maintained full and the green or fresh agglomerates are charged with a minimum drop or fall.

The heating gas for coking is introduced through the gas inlet 6. Any appropriate source of heating gas (inert to the charge under the conditions of coking) may be used. Thus, the heating gasmay be producer gas, illuminating gas, oil gas, natural gas, coke oven gas, water gas, and similar fuel gases, extraneously heatedwhere necessary. The combustion gases resulting from burning such fuel gases; oil or coal (or similar solid carbonaceous fuel) may be used as the heating gas. Such combustion gases may be the exhaust gases from a contiguous thermic operation. When` using such combustion gases, it may be desirable or even necessary to add a small quantity of unburnt fuel gas to the combustion gases in order to react with' or neutralize any oxidizing gases, such as excess oxygen therein. Other inert gases, such as nitrogen, superheated steam, and the like, may also be used as the heating gas.

TheV heating gas must be substantially devoid of oxidizing influences. During the early or formative stage of coking, oxygen or oxidizing influences deleteriously affect the coking constituent or fraction of the agglomerate, and it is particularly important that this stage of the coking operation be conducted in the absence of such oxidizing influences. Oxidizing influences should also be avoided during the later stages of the coking operation since they tend to consume the coke.

The heating gas may as a result of its method of production or previous use be of 'appropriate temperature for the coking operation. Where the gas is too hot for the contemplated coking operation, it should be appropriately cooled as, for example, by steam, Water or the like. If the heating gas is not of a sufciently elevated temperature for the coking operation, it must be appropriately heated. This may be advantageously accomplished by recuperation, or by regeneration, or by adding thereto an appropriate volume of a hotter gas, or by combusting some of the gas itself or a combustible constituent added thereto for the purpose.

' The heating gas enters the chamber 9 and is distributed through the openings of the vertical wall 12 into the coking chamber 8. The gas flows transversely through the body of agglomerates in the coking chamber and out through the openings in the sloping side wall 13 into the chamber 10 and to the gas outlet 7. The heating gas may be forced through the apparatus, but is preferably drawn through by suction fans communicating-with the gas outlet 7.

Some air unavoidably enters the hopper .22 during the charging operation. 'I'he deleterious effect of this airis minimized by the provision of the pipe 24 which serves to suck the air from the hopper into the gas-exiting chamber 10. Even when the swinging gate 23 is closed, some air is likely to leak into the charging hopper, and such air is likewise drawn through the pipe 24 into the chamber 10. Similarly, the pipe 29 draws any air entering the discharge chute 25 into the chamber 10. The draft created by the exiting gases in the flue 7 establishes a sufficient suction in the pipes 24 and 29 to inhibit the flow into the active coking zone of the chamber 8 of any oxidizing gas resulting from the entrance of air through either the charging or discharging device. Where the heating gas is forcedthrough the furnace (instead of drawn through by suction as in my preferred practice), the pipes 24 and 29 are omitted, since they would be inoperative in that case.

The present invention is particularly applicable to that method of coking described in my copending patent application, Serial No. 382,273;

filed July 30, `1929, (whichhas since issued into Patent No. 1,877,123 of September 26,1932), and characterized as rapid coking. In this method of coking, the agglomerates are initially subjected to a high temperature rapid coking treatment so that a substantial layer of coke forms on the surface of the agglomerate in a relatively short time interval and while the main inner mass of the agglomerate remains substantially unaltered. The high temperature heat treatment is thenil continued until the entire agglomerate is coked. In accordance with the present invention, large volumes of heating gas may be passed through a relatively shallow or narrow body of agglomerates at high velocity. This insures rapid, as Well as uniform, heating of the agglomerates to the requisite. coking temperature. I

Merely by way of example, I give the following illustration of a coking apparatus embodying the `invention which has given excellent service under commercial operating conditions. The structure 5 had an inside length of about 12 feet, an inside width of 4 feet and an inside height of about 71/2 feet. 'I'he coking chamber 8 extended across the entire width of the chamber and was about 16 inches deep or wide at the top and about 23 inches deep or wide at the bottom. The area of the openings in the walls 12 and 13 of the coking chamber was approximately 30% of the entire area of each wall. The gas inlet 6 was 42 inches in diameter and the gas outlet 7 was 36 inches in diameter.

When practicing high temperature rapid coking in the apparatus of the invention, the heating gas should be of such temperature that the surface of each agglomerate is rapidly heated to 800 C. or higher. I have obtained satisfactory results with va heating gas entering the body or column of agglomerates in the chamber 8 at a temperature of from 800 to 1000 C. and exiting from the column of agglomerates at a temperature of from 700 to 800 C., but not lower than 550 C. 'Ihe optimum conditions for uniformly producing the contemplated shell of coke on each agglomerate occur with the lowest temperature drop from the gas inlet to the gas outlet. This condition limits the Width of the column of agglomerates in that region where the coke shell lis being formed. Furthermore, in order to produce a shell of coke on each agglomerate in the shortest time possible, it is necessary to pass as large a volume of heating gas as possible through the column of agglomerates. In an apparatus of the dimensions given in the preceding paragraphs, I have obtained satisfactory results by passing through the coking chamber 8 approximately 6,250 cubic feet of gas at a temperature of about 900 C. per minute.

The method and apparatus of the invention, while particularly adapted for practicing the aforementioned method of rapid coking, is equally applicable to other methods of coking. Thus, the method of the invention may be employed where the agglomerates are gradually raised to the required temperature of coking, this being effected by passing through the coking chamber of the invention a heating gas of progressively increasing temperature. The coking may be made continuous by dividing the coking chamber into vertical zones through each of which gas of different temperature is passed. If desired, the heating gas exiting from diierent zones in the coking chamber may be separately exhausted from the apparatus.

1. The method of coking agglomerates of mixed zinciferous and carbonaceous reducing materials containing a coking agent which comprises progressively advancing a body of the agglomerates through a coking chamber, heating the agglomerates to their coking temperature in the course of their travel through said chamber by passing a hot substantially non-oxidizing gas through and in direct contact with the body f agglomerates in a direction approximately transverse to the direction of travel of the agglomerates through the chamber, the temperature of said gas as it enters the agglomerates being at least 800 C. and its temperature on leaving the agglomerates being not lower than 550 C., and subjecting the coked agglomerate discharge end of said chamber to suicient suction to inhibit the flow-into the active coking zone of thechamber of any oxidizing gas resulting from the entrance of air through the coked agglomerate discharging device of the chamber.

2. The method of coking agglomerates of mixed zinciferous and carbonaceous reducing materials containing a coking agent which comprises progressively advancing a `body of agglomerates through a coking chamber, heating the agglomerates to their coking temperature in the course of their travel through said chamber by passing a hot substantially non-oxidizing gas through and in direct contact with the body of agglomerates in a direction approximately transverse to the direction of travel of the agglomerates through the chamber, the temperature of said gas -as it enters the agglomerates being at least 800 C. and its temperature on leaving the agglomerates being not lower than 550 C., and subjecting the fresh agglomerate charging end of said chamber to suiiicient suction to inhibit the flow into the active coking zone of the chamber of any oxidizing gas resulting from the entrance of air through the fresh agglomerate charging device of the cham--I ber.

, .3. The method of coking agglomerates of mixed zinciferous and carbonaceous reducing materials containing acoking agent which comprises progressively advancing a body of the agglomerates through a coking chamber, and heating the agglomerates to their coking temperature in the course of their travel through said chamber by passing a hot substantially non-oxidizing gas through and in direct contact with the body of agglomerates in a direction approximately trans-l verse to the direction of travel of the agglomerates through the chamber, the temperature of said gas` as it enters the agglomerates being at least 800 C.v and it's temperature on leaving the agglomerates being not lower than 550 C.

4. The method of coking agglomerates of mixed zinciferous and carbonaceous reducing materials containing a coking agent which comprises progressively advancing a body of the Iagglomerates by gravity' through an upright coking chamber, and heating the agglomerates to their` coking temperature in the course of their travel through said chamber bypassing a hot substantially non-oxi- 'gas through and in direct contact with the body of agglomerates in adirection approximately transverse to the direction of travel of the agglomeratesthrough the chamber, said hot gas entering the agglomerates at a temperature of at least 800 C. and leaving the agglomerates at a temperature not lower than 550 C.

5. 'Ihe method of coking agglomerates of mixed 115 zinciferous and carbonaceous reducing materials containing a coking agent, which comprises passing hot substantially non-oxidizing gas through a shallow body of the vagglomerates in the form of a narrow vertical column at a temperature sufliciently high to coke the agglomerates, the

temperautre range of the gases between the point of entering the body of agglomerates and the point of leaving the body of agglomeratesv being narrow in order to obtain practically uniform and substantially simultaneous coking of the agglomerates in actual contact with the gases, saidvhot gases being passed transversely through the narrow column of agglomerates, and having an entering teniperature of at least 800 C. and an 130 exiting temperature of not less than 550 C.

` EARL H; BU'NCE.

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