Numerical Simulation of Combustion of Circulation Fluidized Bed Biomass Boiler

Based on a 75t/h circulation fluidized bed biomass boiler with rice hull,wheat straw,maize straw and one kind of coal being fuel.The FLUENT software is used to simulate combustion process, temperature field, distribution of CO2 and O2 concentration with NOx emission.The results reveal that:temperature decreases gradually from bottom to upper and from center to periphery in the boiler.When the coal is combusted,the temperature is the highest.Comparing with boilers that burn coal,biomass boilers emit less NOx and there is the least NOx emission when rice hull is combusted.The results of this numerical simulation offer a reference to design and operation of circulation fluidized bed biomass boilers. Key word: biomass,circulation fluidized bed biomass boiler,combustion,numerical simulation. I.INTRODUCTION Biomass has aroused widespread interest in the world as new energy.To other fossil fuel,its merit includes little pollution,abundant,renewable.At the same time,circulation fluidized bed boilers have their own advantagements with broad compatibility of fuel,low pollutant emission and load adjusting easily.Therefore, circulation fluidized bed biomass boilers can drop combustion pollution to the lowest In this article,the FLUENT software is used to simulate the combustion process of a CFD biomass boiler with rice hull,wheat straw,maize straw and coal as fuel,respectively simulate temperature field,concentration distribution of CO2 and O2 and NOx prodution.The results are contrasted to analyse the difference of fuel and NOx production (4、7) .