US3232845A - Method for making coke - Google Patents

Description

United States Patent 3,232,845 METHOD FOR MAKING COKE Karl R. Komarek, Lombard, Ill., and Kenneth F. Polgreen, Minneapolis, Minn., assignors to Komarek-Greaves and Company, Chicago, 10., a corporation of Illinois No Drawing. Filed Sept. 19, 1960, Ser. No. 58,150 4 Claims. (Cl. 201-7) This invention relates to a method for the production of coke and char. More particularly, this invention relates to the production of coke and char briquettes having a wide variation in properties from starting materials not ordinarily considered to possess coking characteristics and Without the addition of a coking or binding agent.

The carbonization of carbonaceous materials, and especially coal, has been the subject of scientific investigation for many centuries. Coal of the required binding characteristics, known generally as coking coal, is heated in an oven. The tars are melted and the lighter ingredients pass off as gas. Within the body of the fuel, pitch is formed-a residuum from the distilling tar-and the carbonization of that pitch forms a binder to the particles of coked coal.

Carbonization, sometimes followed by briquetting of generally non-coking coal is also known. However, to achieve satisfactory results, the inclusion of a high proportion of coking coal or the addition of binders has been considered necessary and even critical if coke briquettes are desired. Various binders which have been used include pitch, oil tar, oil tar pitch and oil-gas tar.

Finally, it has been known to submit coking coal to a pre-coking step at temperatures from about 350 to 550 C. However, the heat must be applied for from 2 to 10 hours, and it is further required that the coal be cooled before briquetting. It is also known to preheat coking coals to just below the point of active decomposition followed by carbonization. However, neither of these processes is applicable to non-coking coals.

It is, therefore, an object of this invention to provide a simple and uncomplicated process for the production of coke and coke briquettes which overcomes the disadvantages of prior art processes.

It is another object of this invention to provide a process for the production of coke or char with a wide variation in properties ranging from low volatile metallurgical grade coke to high volatile material resembling or identical to charcoal. 1

Still another object of this invention is to provide a process for producing coke and coke briquettes in which the starting materials may cover a broad range of carbonaceous materials.

It is a further object of this invention to provide a process for the production of metallurgical grade coke and coke briquettes from coals considered to be noncoking.

It is a still further object of this invention to provide a process for producing coke and coke briquettes from non-coking coals without the inclusion of coking coals or the addition of any binding agent.

Generally, our process comprises three essential steps. First, the coal or carbonaceous material is heated to a temperature above its decomposition temperature. After a precisely determined amount of decomposition, the

heated material is compacted or briquetted by means of pressure alone into suitably sized briquettes which are then carbonized in any suitable device at a temperature above the briquetting temperature.

More particularly, the three essential steps comprise heating the carbonaceous material, preferably in a stream of gas, to a temperature within the range 400 F. to 900 R, such temperature, of course, being variable depending upon the starting material. The extent of decomposition is controlled by accurately controlling the temperature of the gas as well as the residence time of the material in the gas stream. The heated coal is immediately briquetted by means of pressure alone, and we have found that pressures generally above ordinary briquetting pressures are preferable. Wyoming sub-bituminous coal, for example, was compacted into satisfactory briquettes at a pressure of 20,000 psi. after a residence time of 10-20 seconds at a temperature of 675 F. Finally, the briquettes are carbonized, or coked, in a vertical shaft furnace or other suitable device at a temperature generally between 900 F. and 2000? F., depending on the volatile content desired in the final coke.

We have found that cokes in briquette form of a wide range of properties may be produced by our process from a variety of carbonaceous materials.

Example I Metallurgical grade coke was made from non-coking sub-bituminous coal of the following analysis:

As recd. Dry Pure coal *Buttons will hardly hold together.

The coal was heated to a temperature of 700 F. for a period of 10 seconds and briquetted. The analysis of the briquettes was:

Pure coal Moisture As Crushing strength lbs/sq. in.

The briquetting pressure was 20,000 lbs. per projected square inch of briquet surface. This gave the briquettes a weight per cu. ft. equal to 37.8 lbs.-%" sq. mesh.

The briquettes were then heated to (1) 1550 F. and

(2) 1900 F., one group being heated at each temperature. The coked briquettes had the following analysis 4 We claim: 1. A method for producing coke briquettes from nor- Yield, wt. per cu. ft 65.0%+% S.M.

B.S.S.I.=0, No cohesion 00.6%+% S.M., 34.1 lbs. per

cu. ft.+% S.M.

In carrying out the briquetting, the temperature of mally non-coking carbonaceous material without the use the coal in the'foregoing example was about 700 F. and in this connection, the briquetting of the coal takes place with the latter at a temperature within the range of 400 F. to 900 F.

The briquetting pressure in the foregoing example was 20,000 p.s.i. and, as stated, pressures above ordinary briquetting pressures are preferable, namely, within the range of 15,000 p.s.i. to 40,000 p.s.i.

We have referred above to the extent of decomposition being controlled by the temperature of the gas, as well as the residence time of the material in the gas stream. For instance, the temperature of the gas stream in the above example was 700-F. and the time in which the coal was subjected to the gas stream for the purpose of heating it up to a temperature of 700 F. was 4 seconds and, as stated, the coal was held at this temperature for 10 seconds and then briquetted at about 700 F. In this connection the gas stream has been found satisfactory when it has a temperature within the range above referred to and for a time period between 4 seconds and seconds. For each type of coal and temperature there is an optimum residence time. If the coal is held at the heating temperature for too long a period, decomposition will progress to a point where the coal cannot be briquetted by means of pressure alone. If the residence time is too short the briquettes will not have adequate strength and the resulting coke will lack mechanical strength.

While we have referred in the above example to metallurgical grade coke made from non-coking sub-bituminous coal, it is to be understood that the invention may be carried out using non-coking coals from various sources with equally good results and, therefore, the material described in Example I is purely illustrative.

The present invention will thus be seen to completely and effectively accomplish the objects enumerated hereinabove. It will be realized, however, that various changes and substitutions may be made to the specific embodiments disclosed herein for the purpose of illustrating the principles of this invention, without departing from these principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

of binding agents comprising the steps of: heating the normally non-coking carbonaceous starting material to a temperature which is above the decomposition temperature of said carbonaceous material and between 400 F. and 900 F. for a period of time not greater than 30 seconds to drive off free and combined moisture and a portion of the volatile materials of said carbonaceous material; briquetting said carbonaceous material at pressures between 15,000 and 40,000 pounds per square inch while heated to a temperature between 400 F. and 900 F. to form a dense strong briquette of partially decomposed and partially devolatized carbonaceous material and thereafter carbonizing said briquettes at a temperature between 900 F. and 2000 F. to form a coke briquette of predetermined strength and density.

2. The method defined in claim 1 wherein the carbonaceous starting material is heated in a stream of gas.

3. The method defined in claim 2 wherein carbonaceous starting material is heated to a temperature between 700 F. and 900 F. for a period of time between 4 and 30 seconds.

4. The method defined in claim 3, wherein the carbonaceous material is briquetted at a pressure of about 20,000 pounds per square inch and the briquettes are carbonized at a temperature between 1,550 F. and 1,900 F.

References Cited by the Examiner UNITED STATES PATENTS 2,594,226 4/1952 Shea 202-26 2,706,706 4/1955 Pettyjohn 202-26 2,824,790 2/1958 Gregory et al. 202-26 X 2,838,386 6/1958 Mason 202-26 X 2,937,080 5/1960 Komarek et al. 44-10 3,093,463 6/1963 Madley 44-10 FOREIGN PATENTS 1,062,128 4/1954 France.

210,466 1/ 1924 Great Britain.

MORRIS O. WOLK, Primary Examiner.

RICHARD D. NEVIUS, ALPHONSO D. SULLIVAN,

DONALL H. SYLVESTER, Examiners.

I. A. FEKETIS, I. H. HALL, M. H. SILVERSTEIN,

J. T. ZATARGA, Assistant Examiners.

Claims (1)

1. A METHOD FOR PRODUCING COKE BRIQUETTES FROM NORMALLY NON-COKING CARBONACEOUS MATERIAL WITHOUT THE USE OF BINDING AGENTS COMPRISING THE STEPS OF: HEATING THE NORMALLY NON-COKING CARBONACEOUS STARTING MATERIAL TO A TEMPERATURE WHICH IS ABOVE THE DECOMPOSITION TEMPERATURE OF SAID CARBONACEOUS MATERIAL AND BETWEEN 400*F. AND 900*F. FOR A PERIOD OF TIME NOT GREATER THAN 30 SECONDS TO DRIVE OFF FREE AND COMBINED MOISTURE AND A PORTION OF THE VOLATILE MATERIALS OF SAID CARBONACEOUS MATERIAL; BRIQUETTING SAID CARBONACEOUS MATERIAL AT PRESSURES BETWEEN 15000 AND 40000 POUNDS PER SQUARE INCH WHILE HEATED TO A TEMPERTURE BETWEEN 400* F. AND 900*F. TO FORM A DENSE STRONG BRIQUETTE OF PARTIALLY DECOMPOSED AND PARTIALLY DEVOLATIZED CARBONACEOUS MATERIAL AND THEREAFTER CARBONIZING SAID BRIQUETTES AT A TEMPERATURE BETWEEN 900*F. AND 2000*F. TO FORM A COKE BRIQUETTE OF PREDETERMINED STRENGTH AND DENSITY.