Experimental Study Of The End Effect On The Internal Recycling Of Circulating Fluidized Bed Boilers

Combustion technology of circulating fluidized beds (CFB ) is being widely used in boilers for its high efficiency, low environmental pollution and good economics. This thesis introduces the characteristics of circulating fluidized beds and the gas-solid two-phase hydrodynamics. To aim at the main problems of industrial circulating fluidized bed boilers and the shortcomings of engineering countermeasures, the author explores to enhance the internal recycling with simple ways.To establish a method of enhancing the internal recycling, the author designs the experimental system of a circulating fluidized bed boiler and studies the influence of the exit structures on the hydrodynamic characteristics. Through the experimental research and theoretical analysis, it is disclosed that the exit configurations affect on internal recycling of the circulating fluidized bed in the aspect of the gas-solid two-phase flow mechanism.The experimental results show that bed exit configurations greatly influence the hydrodynamics in the circulating fluidized bed boiler. Using a smooth exit, the bed density is dilute in the upper part and dense in the under part. As for the unsmooth exits, the bed density distribution is as followings: dense in the upper part and dilute in the under part, or dense in the upper part and under part. When the abrupt height increases, the hydrodynamics will be affected greatly. However, the influence of the abrupt height disappears if the abrupt height attains the maximum reachable height for the particles at the...