Numerical Simulation on Combustion Characteristics of Co-Firing Biomass Syngas and Coal in a 660 MW Utility Tower Boiler

Abstract

Utilize the biomass energy and adopt carbon capture and storage technologies could reduce the CO2 emission effectively. Biomass gasification is an effective ways to use the biomass. Co-firing biomass syngas with pulverized coal under oxy-fuel condition in utility boiler can combine the two advantages to reduce the CO2 emission. In this paper, a new proposed combustion mechanism was used to investigate the combustion characteristics of co-firing different types biomass syngas and coal in a 660 MW double reheat tower boiler. The influence of syngas composition and oxy-fuel condition on temperature distributions and flue gas components was analyzed when total input heat of the boiler was steady. The results show that the temperature and the emission of the NO and CO2 decrease in co-firing conditions, the NO mass concentration reduced up to 10.2% in co-firing cases. Biomass syngas with higher H2 and less CO and CH4 composition contributes to lower CO2 emission and higher boiler temperature, which can improve plant performance. The oxy-fuel condition also affects the combustion characteristics to some extent. With the increase of O2 volume fraction, the temperature increases and the O2 consumption decreases. Moreover, the NO mass concentration increases in oxy-fuel combustion when co-firing biomass syngas and coal with a mixing ratio of 0.1. This study offers reference for boiler’s operation and design optimization for biomass syngas co-firing.KeywordsBiomass syngasCo-firingOxy-fuel combustionNO emissionNumerical simulation