US3839157A

US3839157A - Water spray over transfer mechanism for cooling chars

Info

Publication number: US3839157A
Application number: US00350771A
Authority: US
Inventors: R Hagstrom
Original assignee: Peabody Coal Co
Current assignee: Peabody Development Co
Priority date: 1973-04-13
Filing date: 1973-04-13
Publication date: 1974-10-01
Anticipated expiration: 1991-10-01

Abstract

Char made from lower ranked coals in a horizontal chain grate coking furnace is discharged at the output end of the furnace into a laterally moving horizontal screw conveyor wherein it is quenched, fed laterally, and discharged into the top of a shaft furnace.

Description

United States Patent 1191 Hagstrom 1 Oct. 1, 1974 [54] WATER SPRAY OVER TRANSFER 1,944,192 1/1934 Riddell 202/227 MECHANISM O COOLING CHARS 2,997,427 8/1961 Mansfield 3,591,462 7/1971 Bretz 202/117 Inventor: Robert G. Hagstrom, Nashville,

Tenn.

Assignee: Peabody Coal Company, St. Louis,

Filed: Apr. 13, 1973 Appl. No.: 350,771

US. Cl 202/117, 202/227, 201/39 Int. Cl. .;.C10b 1/00, ClOb 39/12 Field of Search 202/227, 226, 230, 117,

References Cited UNITED STATES PATENTS 9/1918 McDonald 202/227 Primary Examiner-Wilbur L. Bascomb, Jr. Assistant ExaminerD. Sanders Attorney, Agent, or Firm-James H. Littlepage [57] ABSTRACT Char made from lower ranked coals in a horizontal chain grate coking furnace is discharged at the output end of the furnace into a laterally moving horizontal screw conveyor wherein it is quenched, fed laterally, and discharged into the top of a shaft furnace.

4 Claims, 2 Drawing Figures ATMOSPHERE EAIENTEDBBT 1 1 3.839, 1 5T FIGI ATMOSPHERE WATER SPRAY OVER TRANSFER MECHANISM FOR COOLING CHARS RELATED APPLICATIONS Whitten and I-lagstrom, PRODUCTION OF ACTI- VATED CHAR USING A MOVING GRATE STO- KER, Ser. No. 130,737 filed Apr. 2, 1971, now abandoned.

BACKGROUND OF THE INVENTION In utilizing the method disclosed in the Whitten and I-Iagstrom application, supra, the coal, after being charred in a hot carbonizing furnace nearly to the point of complete devolatilization, was dropped off the end of a horizontally moving chain grate into the top of a shaft furnace. While this method is successful with bituminous or higher ranked coals, it was found that char made from lower ranked materials such as peat, lignite, or brown coal and some of the lower volatile subbituminous coals have such extensive surface area that it would undergo excessive oxidation in transit from the coking furnace to the shaft furnace. This was due at least in large part to the presence of small amounts of oxygen in the system.

Another advantage in this over the former system is in the elimination of what may be called a packing factor. As the char moved downwardly through the shaft furnace, it was quenched with cool inert gas which was swept through it. Somehow or other, the char would pack so that the quenching gases were prevented from reaching parts of the mass, so that when this mass was subsequently exposed to the atmosphere, it tended to reignite.

According to the present invention, it is intended now to provide, at the end of the coking oven in which the coal is charred, a hopper into which the char drops from the oven grate, and a water spray for quenching the char as it drops into the hopper. In the bottom of the hopper is a screw conveyor which feeds the hot, wet char into the top of a shaft which constitutes a holding tank. Water is sprayed onto the char in the top of the shaft and a suitable feeder discharges the coal char from the bottom of the shaft.

These and other objects will be apparent from the following specification and drawings, in which:

FIG. 1 is a diagrammatic vertical cross section taken lengthwise of the apparatus; and,

FIG. 2 is a diagrammatic vertical cross section taken transversely through the end of the apparatus.

Referring first to FIG. 1 of the drawings, the material to be charred such as peat, lignite, brown coal, and possibly one'of the lower volatile sub-bituminous coals is fed from a storage bin through a scale 12 and hopper inputs 14 ofa hot carbonizer furnace 16 (see Mansfield U.S. Pats. Nos. 3,434,932 and 3,434,933 for further details of this type of coking furnace) in which the material is spread onto a horizontally moving chain grate 18 by means of a spreader gate 20 to form a bed 22. The chain grate runs over

end sprockets

23, 24 in the direction indicated, the sprockets being conventionally driven and supported by shafts and bearings, not shown, and beneath the top run of the chain grate is a zoned airbox 26. As the bed passes over the airbox zones (zones 16, for example), various amounts of air and steam may be zone fed upwardly through the bed and hot combustion by-product gases may be downdrafted through the bed. The net result being that the material is charred as it moves through the furnace and as the char drops off the end of the grate run which is at the output end of the furnace. It is almost completely devolatilized, so hot and with so much surface area that it would immediately oxidize if exposed to air. To prevent this, the following are provided:

Disposed within the housing of the furnace so as to catch the char as the latter drops off the end of the grate run is a hopper 28 in the bottom of which runs a screw conveyor 30. As the hot char drops towards and into the hopper, it is sprayed with water issuing from spray jets 32. Steam issues upwardly via stack 33 and the wet char is screwed laterally through a restricted passage 34 into the top end of a shaft-like holding tank 36 from the bottom of which the then cooled char is discharged through a suitable air-lock feeder 38.

As the wet char enters the top of holding tank 36, it is again sprayed with water issuing from suitable jets 40. The steam resulting from this spraying, as well as from the water still in the char from the previous spraying, exhausts through the char as the latter is screwed through the restricted passage 34, whereupon it mingles with the steam and other gases issuing from the char in the hopper and exhausts through the stack 33. Thus, no air can follow the char into the holding tank. By adjusting the amounts of spray water issuing from

jets

32 and 40, a carbon/water ratio can be established such as to produce adequate cooling of the char while at the same time producing a char which is reasonably dry.

This process cools high surface area char rapidly below the ignition point in the absence of any oxidizing gases and greatly enhances fixed carbon recovery without materially increasing the ash content of the char. Since the sprayed water cools the char and is vaporized during the cooling period, an essentially dry char is produced; and, by the use of this system, there is no infusion of air from leaks or dumping grates at the critical times and places where the danger of oxidation are most serious.

I claim:

1. In an apparatus for producing char comprising,

a carbonizer furnace having laterally disposed input and output ends, means for feeding material to be charred to the input end of the furnace,

endless chain grate means for conveying the material horizontally through the furnace from the input to the output ends thereof,

and means for feeding air in controlled amounts through the material as the latter is conveyed through the furnace so as to create limited combustion sufficient to raise the temperature of the material substantially devolatilized the same and produce thereof a hot char,

the improvement which comprises a horizontal trough disposed below the output end of the furnace in position to receive the hot char freely falling from the chain grate at the output end of the furnace,

said trough terminating in an open end,

a holding tank having an upper end portion, the open end of the trough terminating in the upper end portion of the holding tank, whereby char issuing from the open end of said trough falls by gravity into said holding tank,

conveyor means in said trough for feeding the char from the trough to the tank,

water spray means for spraying water onto the char as the latter is received into the trough from the furnace; and means for discharging the char from the bottom of the holding tank.

2. The improvement recited in claim 1, and water spray means for spraying water onto the char as the latter is fed into the holding tank from the trough.

3. The improvement recited in claim 1, and means providing a restriction in the passage for the char between the trough and the holding tank said conveyor being a screw conveyor running from the bottom of the trough to the upper portion of the holding tank, a convolution of said screw conveyor occupying said restrict1on.

4. In combination with a carbonizer furnace for producing char, including means providing a furnace housing having a free-falling char discharge,

a horizontal trough for receiving free-falling char from said discharge, said trough having an open end,

a holding tank having an upper end portion, the open end of the trough terminating in the upper end portion of the holding tank, whereby char discharged from the open end of the trough falls freely into said holding tank,

conveyor means for feeding char through said trough to said tank,

means for spraying water on said char as the latter falls freely into said trough,

and means for spraying water onto the char as the latter falls freely into the holding tank from the trough.

Claims

1. In an apparatus for producing char comprising, a carbonizer furnace having laterally disposed input and output ends, means for feeding material to be charred to the input end of the furnace, endless chain grate means for conveying the material horizontally through the furnace from the input to the output ends thereof, and means for feeding air in controlled amounts through the material as the latter is conveyed through the furnace so as to create limited combustion sufficient to raise the temperature of the material substantially devolatilized the same and produce thereof a hot char, the improvement which comprises a horizontal trough disposed below the output end of the furnace in position to receive the hot char freely falling from the chain grate at the output end of the furnace, said trough terminating in an open end, a holding tank having an upper end portion, the open end of the trough terminating in the upper end portion of the holding tank, whereby char issuing from the open end of said trough falls by gravity into said holding tank, conveyor means in said trough for feeding the char from the trough to the tank, water spray means for spraying water onto the char as the latter is received into the trough from the furnace; and means for discharging the char from the bottom of the holding tank.

3. The improvement recited in claim 1, and means providing a restriction in the passage for the char between the trough and the holding tank said conveyor being a screw conveyor running from the bottom of the trough to the upper portion of the holding tank, a convolution of said screw conveyor occupying said restriction.

4. In combination with a carbonizer furnace for producing char, including means providing a furnace housing having a free-falling char discharge, a horizontal trough for receiving free-falling char from said discharge, said trough having an open end, a holding tank having an upper end portion, the open end of the trough terminating in the upper end portion of the holding tank, whereby char discharged from the open end of the trough falls freely into said holding tank, conveyor means for feeding char through said trough to said tank, means for spraying water on said char as the latter falls freely into said trough, and means for spraying water onto the char as the latter falls freely into the holding tank from the trough.