Simulation of emission performance and combustion efficiency in biomass fired circulating fluidized bed combustors

In this study, the combustion efficiency and the emission performance of biomass fired CFBs are tested via a previously published 2D model [Gungor A. Two-dimensional biomass combustion modeling of CFB. Fuel 2008; 87: 1453-1468.] against two published comprehensive data sets. The model efficiently simulates the outcome with respect to the excess air values, which is the main parameter that is verified. The combustion efficiency of OC changes between 82.25 and 98.66% as the excess air increases from 10 to 116% with the maximum error of about 8.59%. The rice husk combustion efficiency changes between 98.05 and 97.56% as the bed operational velocity increases from 1.2 to 1.5 m s(-1) with the maximum error of about 7.60%. CO and NOx emissions increase with increasing bed operational velocity. Increasing excess air results in slightly higher levels of NOx emission. A significant amount of combustion occurs in the upper zone due to the high volatile content of the biomass fuels. (C) 2009 Elsevier Ltd. All rights reserved.