Low bed pressure drop circulating fluidized bed boiler and the combustion process

摘要

This invention is about a low bed pressure drop circulating fluidized bed (CFB) boiler and the combustion process, associated with fast bed CFB combustion technology. The technical scheme for the invention firstly ensures the CFB boiler to be operated at a fast bed fluidization condition, controlling the combustor temperature at 850°C-930°C, the fluidizing air velocity at 4-6.2m/s and the average size of the bed material in the combustor smaller than 300µm, and then to keep the solid concentration above of the secondary air inlet in the combustor is at 1-15kg/m 3 for fast bed fluidization. This invention reduces the solid concentration inside combustor, and the total bed inventory, so it significantly reduces the power consumption for the primary air and secondary air fan, resulting in less power consumption of the auxiliary fans. In addition, due to the reduction of the solid concentration in the combustor, the gaseous mixing is improved and combustion intensity is enhanced, resulting in an increment of combustion efficiency. Due to the reduction of the height of the dense bed, the number of the particles elutriated and entrained to the upper combustor is reduced, resulting in less intense of the erosion for the water wall membrane heating surfaces.