1. Technical Field
The present invention relates to improvements in the combustion chamber for effective utilization of rubber scrap such as used tires and waste from the tire manufacturing process as a fuel for coal-fired boilers or the like and improvements in the method for mix-burning coal and such rubber scrap.
2. Prior Art
When metal-containing rubber scrap such as used tires are burned at high temperature, the metal contained therein is melted and stuck to the stoker of the combustion equipment. Therefore, generally such rubber scrap has not been utilized as a boiler fuel.
Some rubber scrap has heretofore been reclaimed and used as a fuel for the production of cement or a blast furnace fuel in steel mills but the shipment of rubber scrap such as used tires and wast from a tire manufacturing plant to a site of use, e.g. a blast furnace located in a remote locality, involves much transportation costs. Moreover, if rubber scrap of this type is burned in large quantities, several component materials of the rubber adversely affect the combustion. Mainly for these two reasons, this kind of rubber scrap has so far found little usage.
Furthermore, if a large amount of metal-containing rubber scrap such as automotive tires containing bead wires, steel cords, etc. is burned in a furnace, the molten metal having a greater specific gravity sinks and sticks to the stoker, with the result that the flow of air through the stoker is obstructed or mechanical troubles are encouraged.
In the usual type of furnace, the same problems as above are encountered when it is charged with tires or the like rubber wastes together with other fuels from the same charging port, whether concurrently or sequentially.
To avoid this problem associated with molten metal, Japanese Patent Application Kokai No. 105308/1988 proposed a combustion system in which rubber scrap such as used tires are burned on a fluidized bed formed by sand or the like material, which is to be recycled, in a furnace. This combustion method, however, requires a special equipment and a time-consuming operation for separating the metal from the sand constituting the fluidized bed and, in this sense, is not practically useful.
The present invention overcomes the above problems. Thus, the invention is directed to a boiler or other combustion chamber and a method for burning coal and rubber, scrap together, which solve the problems associated with the disposal of used tires which is currently a major nation-wide problem requiring a neat solution and of refuses from the tire manufacturing process and enable effective utilization of the potential thermal energies of such refuses as fuels.