Influence of Operating Parameters on Chlorine Release and Pollutant Emission Characteristics of a 130 t/h BCFB Combustion System.

Abstract

A 130 t/h biomass circulating fluidized bed (BCFB) boiler combustion system model, considering the chloride release and pollutant emissions during the biomass combustion, was established using the Modelica language. The effects of the biomass feed amount, limestone amount, excess air coefficients, and different ratios of primary and secondary air on the boiler furnace temperature and flue gas composition (O2, CO2, SO2, HCl, and KCl) were investigated. Upon the biomass feed amount step change, the variation ranges of NO and KCl concentrations were very large, which were 18.58 and 21.16% of the before step value, respectively. The step change of the limestone input had little effect on b ed temperature in the dense phase zone, but it could obviously reduce the SO2 concentration. The concentration of SO2 in flue gas decreased by 22.56% when the limestone input increased by 50%. The removal rate of SO2 gradually decreased with the increase of the limestone amount. The SO2 desulfurization rate decreased by 68.30% when the amount of limestone increased from 0.0275 to 0.0825 kg/s. More NO would be generated and KCl concentration would be significantly reduced with the increase of the excess air coefficient. When the ratio of primary and secondary air was 4:6, the NO concentration in flue gas was lower than 86.06 mg/Nm3.