METHOD AND DEVICE FOR USE OF BIO FUEL OR WASTE MATERIAL IN ENERGY PRODUCTION

摘要

Method and apparatus for using biofuel or waste material or both for energy production. The biofuel or the waste material is gasified in a fluidized bed gasifier (10), preferably a circulating fluidized bed gasifier. The gas produced in the gasifier is introduced into a boiler (12) equipped with fossil fuel burners (28, 28'28''), typically burners for pulverized coal. The gas is introduced at a level above the burners. Ash from the boiler may be used to form the bed of the gasifier. For control of NOx, the gas is burned in the upper part of the boiler at a low temperature level of 800 DEG -1050 DEG C. (1472 DEG -1922 DEG F.), preferably 850 DEG -900 DEG C. (1562 DEG -1652 DEG F.), and with a small excess air content of about 5-10 percent. In a second embodiment, the raw gas may be cleaned of harmful or noxious components, and cooled if desired, between the gasifier and the boiler in an additional circulating fluidized bed reactor (152) having a bed of coal ash.