Multifuel bubbling bed fluidized bed combustor system

摘要

In order to be able to handle multiple fuels in a bubbling-bed fluidized bed combustor, a number of elements are combined together and a number of systems are described which utilize these elements in order to be able to appropriately process different types of fuels. With respect to the handling of multiple fuels by a bubbling-bed fluidized bed combustor which need not be reconfigured for each type of fuel, the combustor in the subject invention is provided with a closely-coupled pyrolyzer or gasifier. The close-coupled pyrolyzer not only permits the processing of virtually any type of fuel into two fuel streams which are immediately usable by the combustor but also has certain advantages in terms of reducing environmental pollutants. The above-mentioned close- coupled pyrolyzer also results in improved performance aside from the pollution aspects mentioned above. The close coupling of the pyrolyzer to the fluidized bed combustor also allows fluid bed combustion systems to be built in larger capacity than heretofore possible. In one aspect of the subject invention, the close-coupled pyrolyzer permits the production of higher temperature flue gases than would be done with a fluidized bed combustor without the pyrolyzer. The subject invention also allows the use of high-moisture fuels and avoids the efficiency loss, output loss and the increased boiler size that is normally associated with those fuels. The above advantages of the close-coupled pyrolyzer are improved by the provision of some specially designed auxiliary apparatus, such as a specialized deep-bed pyrolyzer, a specialized screw feeding system and the utilization of under-the-bed cooling tubes in a fluidized bed combustor. The above has detailed the building blocks useful in numerous types of systems, three of which will be described hereinafter; namely, a system for processing refuse-derived fuels, a system for processing hazardous fuels and combined-cycle gas.