Heating – Work chamber having heating means – Having means by which work is progressed or moved mechanically
Reexamination Certificate
2000-10-05
2001-09-18
Wilson, Gregory (Department: 3749)
Heating
Work chamber having heating means
Having means by which work is progressed or moved mechanically
C432S239000, C202S248000, C202S262000
Reexamination Certificate
active
06290494
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and apparatus for making coke from coal and in particular to a method and apparatus for compacting and feeding coal to a non-recovery coking oven.
BACKGROUND
Coke is a solid carbon fuel and carbon source used to melt and reduce iron ore in the production of steel. During an iron-making process, iron ore, coke, heated air and limestone or other fluxes are fed into a blast furnace. The heated air causes combustion of the coke which provides heat and a source of carbon for reducing iron oxides to iron. Limestone or other fluxes may be added to react with and remove the acidic impurities, called slag, from the molten iron. The limestone-impurities float to the top of the molten iron and are skimmed off.
In one process, known as the “Thompson Coking Process,” coke used for refining metal ores is produced by batch feeding pulverized coal to an oven which is sealed and heated to very high temperatures for 24 to 48 hours under closely controlled atmospheric conditions. Coking ovens have been used for many years to covert coal into metallurgical coke. During the coking process, finely crushed coal is heated under controlled temperature conditions to devolatilize the coal and form a fused mass having a predetermined porosity and strength. Because the production of coke is a batch process, multiple coke ovens are operated simultaneously, hereinafter referred to as a “coke oven battery”.
At the end of the coking cycle, the finished coke is removed from the oven and quenched with water. The cooled coke may be screened and loaded onto rail cars or trucks for shipment or later use or moved directly to an iron melting furnace.
The melting and fusion process undergone by the coal particles during the heating process is the most important part of the coking process. The degree of melting and degree of assimilation of the coal particles into the molten mass determine the characteristics of the coke produced. In order to produce the strongest coke from a particular coal or coal blend, there is an optimum ratio of reactive to inert entities in the coal. The porosity and strength of the coke are important for the ore refining process and are determined by the coal source and/or method of coking.
Coal particles or a blend of coal particles are charged into hot ovens on a predetermined schedule, and the coal is heated for a predetermined period of time in the ovens in order to remove volatiles from the resulting coke. The coking process is highly dependent on the oven design, the type of coal and conversion temperature used. Ovens are adjusted during the coking process so that each charge of coal is coked out in approximately the same amount of time. Once the coal is coked out, the coke is removed from the oven and quenched with water to cool it below its ignition temperature. The quenching operation must also be carefully controlled so that the coke does not absorb too much moisture. Once it is quenched, the coke is screened and loaded into rail cars or trucks for shipment.
Because coal is fed into hot ovens, much of the coal feeding process is automated. In slot-type ovens, the coal is typically charged through slots or openings in the top of the ovens. Such ovens tend to be tall and narrow. More recently, non-recovery or heat recovery type coking ovens have been used to produce coke. Such ovens are described for example in U.S. Pat. Nos. 3,784,034 and 4,067,462 to Thompson. Conveyors are used to convey the coal particles into the ovens and to level the coal in the ovens.
As the source of coal suitable for forming metallurgical coal has decreased, attempts have been made to blend weak or non-coking coals with coking coals to provide a suitable coal charge for the ovens. One attempt is to use compacted coal. The coal may be compacted before or after it is in the oven. While coal conveyors are suitable for charging ovens with particulate coal which is then compacted in the oven, they are generally not suitable for charging ovens with pre-compacted coal. There is a need therefor, for a method and apparatus for charging coking ovens with pre-compacted coal. There is also a need for an apparatus for compacting coal in a short period of time in order to reduce labor and production costs for making metallurgical coke.
SUMMARY OF THE INVENTION
In accordance with the foregoing need, the invention provides an improved coke oven charging device and method for charging compacted coal to a coking oven, the coking oven having an exhaust-flue heated floor, substantially parallel vertical side-walls, a pusher door adjacent an oven entrance, a coke door adjacent an oven exit and an arched substantially closed roof. According to the method, a coke oven pusher and charging machine is moved adjacent the pusher door of the oven. The coke oven pusher and charging machine includes a movable, elongate charging plate having a first end and a second end, retractable side-walls adjacent the charging plate, a first end wall adjacent the second end of the charging plate, a charging plate moving device for moving the charging plate into and out of the oven and a movably separate coal guide section adjacent the first end of the charging plate for spanning an area between the first end of the charging plate and the oven entrance. The coal guide section includes a bottom wall, opposed fixed side walls attached to the bottom wall and opposed second and third end walls movable with respect to the bottom wall and fixed side walls.
Particulate coal is fed to the charging plate between the side walls and second end wall of the coal guide section and to the coal guide section between the second and third end walls to form first and second coal beds. The coal in the first coal bed is compacted between the retractable side walls and first and second end walls. The pusher door is removed from the coking oven entrance and the coke door is removed from the oven exit. Coke is pushed out of the coking oven into a hot car and the coke door is reattached to the oven exit.
A portion of the coal guide section is transported into the oven entrance in order to span a distance between the oven entrance and the charging plate. The second and third end walls are retracted from the bottom wall of the coal guide section in order to deposit uncompacted coal in at least a portion of the oven. The retractable side walls are retracted from the compacted coal on the charging plate. The charging plate containing compacted coal is moved into the oven over the coal guide section while pushing uncompacted coal ahead of the compacted coal so that the uncompacted coal forms a layer of substantially uncompacted coal between the heated oven floor and the charging plate. The second and third end walls are repositioned adjacent the charging plate and the charging plate is retracted from the oven while holding the compacted coal in the oven using the third end wall. Finally, the coal guide section is withdrawn from the oven entrance and the pusher door is reattached to the oven.
In another aspect the invention provides a coke oven charging machine including a mobile frame and a coke oven feed device on the mobile frame. The coke oven feed device includes a movable, elongate charging plate having a first end and a second end, retractable side-walls adjacent the charging plate, first and second end walls adjacent the first and second ends of the charging plate and a shuttle section adjacent the first end of the charging plate for spanning an area between the first end of the charging plate and an entrance to the oven. The shuttle section has opposed shuttle side walls and a shuttle end wall. A charging plate moving device is provided for moving the charging plate into and out of the oven.
In yet another aspect the invention a method for charging coal to a coking oven. The method includes the steps of providing a bed of compacted coal on a first charging plate and a bed of uncompacted coal on a second charging plate. The first charging plate is located outside the oven adjacent an oven entrance and the second chargi
Luedeka Neely & Graham PC
Sun Coke Company
Wilson Gregory
LandOfFree
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