循环流化床二次风射程的数值模拟和实验

Experimental Study and Numerical Simulation of Secondary Air's Jet Length in Circulating Fluidized Beds

以国内某电厂410t／h循环流化床锅炉为原型，用有机玻璃按10：1的比例建立了1套冷模可视化实验装置。在测量二次风喷口所在炉膛截面物料浓度的基础上，对不同二次风速、不同炉膛流化风速条件下二次风的射程进行了实验研究和数值模拟。结果表明：炉膛物料浓度随一次风速的变化而变化，二次风的引入显著地改变了炉膛内物料浓度的分布；在物料特性和喷口特性一定的情况下，二次风的射程随着二次风风速的增加而近似成幂函数增加，其指数在0．5～1之间变化，指数值随着炉膛流化风的增加逐渐减小，且减小幅度逐渐增大。

Taking the 410t/h circulating fluidized bed boiler of a certain power plant as the original, a cold state visible 10：1 scaled observable model, made of plexiglass, has been built. Based on the material concentration found in the furnace＇s cross-section at secondary air＇s injection level, secondary air jet＇s length was determined by tests, as well as by numerical simulation, for different secondary air velocities and different fluidizing air velocities in the furnace. Results indicate that the concentration of the material in the furnace varies with changing primary air velocity, and introduction of secondary air noticeably affects the distribution of material density in the furnace, ff the property of the material and the injection port remain the same, the length of the secondary air jet increases with increasing secondary air velocity, and may be expressed by a power functions with the power index lying between 0.5 and 1. This index reduces at first slower and then quicker, with increasing fluidizing air velocity in the furnace.