| Biomass power generation is attracting more and more attention because its nearly net zero emission of carbon-dioxide and its high fuel flexibility. Compared to coal, biomass has low emission of SOx and particulate matters from the combustion process because its low sulphur and ash content. So biomass utilization played a significant role in the development of environmentally friendly society. Grate-fired boiler has the advantages of low investment cost and high fuel flexibitity and it is the main technology of biomass power generation and heat supply. In this paper, numerical similation of the flow field was carried out with FLUENT software for double-grate biomass fired boiler, the results were validated by experimental data taken from a 1/30 scale cold model of the prototype. Simulations under various primary, secondary and ignition air flow rates and incidence angles and different arch configuration were analyzed to identify the optimum flow field. The operating condition of Case 9 consisted of the secondary air ratio Rf/Rr of 50/50, the air rate RpA/RsA/RIA of 40/40/20, and the up incidence angles of the rear wall secondary air of 30°. This condition can be practically applied for the flow field optimization.The result shows that the incinerator with the front arch and rear arch at the same level has the optimum flow field. Mathematical modeling of flow field and combustion was carried out for the original 48t/h biomass-fired boiler, according to simulation, the parameters distributions of temperature, velocity and species were obtained. It was suggested that adjust an important air flow ratio or fix baffles in the third pass to reduce erosion of supper heater.
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