Experimental And Model Predictive Study On The Effect Of Secondary Air Of The Riser On Solids Circulation Rate In A Dual Circulation Fluidized Bed

The key to keep dual circulating fluidized(DCFB) bed biomass gasifier running steadily is to control the solids circulation rate reasonably. A DCFB cold bench was built to study the effects of characteristics of the air-supply in the two bed, especially the characteristics of secondary air in the riser on the solids circulation rate, and its variation was identified by analyzing the data. The effect of the secondary tuyeres height is of the most significant.Two different mathematical models of pressure drop in the riser was established and the predicted results of the two models were juxtaposed. Pressure drop has different sensitivities effected by a variety of factors. The maximum relative error was the biggest when secondary tuyeres heights were different, which reached12.13%. The mean relative error between the output of the optimal model and the measured values were greater when modes and heights of secondary tuyeres were different. It was6.27%and6.65%, respectivelyA BP neural network to predict solids circulation rate was established with the help of Matlab, the optimal algorithm and network structure were determined via comparison of predictive values calculated by three improved training algorithms. The mean relative error between the output of optimal BP network and the experimental value is merely1.37%, and the maximum relative error was5.75%. The model can accurately predict solids circulation rate effected by characteristics of secondary air,and provides the basis for automatic control of DCFB operation.