Experimental Study On The Biomass Combustion Character In Circulating Fluidized Bed

With the fossil fuel resource decreasing and the serious environmental pollution problems, biomass has been widely appreciated due to its low emissions and inexhaustible natural characteristics. This paper research about tree bark, the main fuel of Yuedian Zhanjiang biomass power plant, which combustion characteristics and pollution emission characteristics were analyzed. And prevention methods of corrosion of biomass boiler heating surface were explored. The main research contents and achievements are as follows:Biomass combustion characteristics experiments were investigated using a thermogravimetric analyzer (TGA), TGA experimental results show that, tree bark and eucalyptus branches differential thermogravimetric (DTG) curves have two obvious peaks of mass loss as eucalyptus leaves have three. With the heating rate increasing, ignition temperature, burn-out temperature, maximal combustion rate, average combustion rate, comprehensive combustion characteristics index of tree bark increase. Similar to tree bark DTG curves still indicate double obvious peaks when the bark was blended with coal at the mass percentage of5%,10%and15%respectively. With the increasing proportion of coal in the blends, the weight loss rate peaks of volatile decrease as the peaks of fixed carbon increase slightly, and the ignition and burn-out characteristics is similar to tree bark and coal respectively.A35.5kW biomass-fired circulating fluidized bed (CFB) experimental platform was built. During adjustment of the boiler a number of problems such as blockage of feed system and flue were successfully resolved. In order to provide guidance for the power plant operation, experiments of pollutants emission characteristics of bark were carried out, and the influence of operating parameters on the emission of pollutants were analyzed.Co-firing of tree bark and coal were carried out on the35.5kW CFB experimental platform. CFB experiments indicate that, compared to tree bark combustion, co-firing makes the heat distribution more uniform in furnace and reduce the CO emission, but the emission of NOx and SO2increase. Meanwhile, HCl concentration in flue gas and Cl in fly ash decrease significantly since the coal ash has significant effect of removal chlorine. Experimental results show that the optimal blended mass percentage of coal is between5%to10%. Experiments on combustion of pure biomass and biomass with anticorrosive agent were carried out in Yuedian Zhanjiang biomass power plant. Results obtained in experiments show that, boiler thermal efficiency was weakly influenced by the anticorrosive agent, and contents of K and Cl in flue ash decreased as contrast to the increase of K and Cl in furnace slag. The content of HCl in flue gas decreases significantly while he NO emission increases.