Performances Evaluation of Biomass Gasification and Synthetic Gas Co-Firing in Coal-Fired Boiler

Optimum condition of gasification process is the key to biomass utilization and synthetic gas co-firing with coal in boiler. Based on an equilibrium RGibbs reactor model, the performances of biomass gasification, such as exergy efficiency and low heating value of synthetic gas, were evaluated under the conditions of biomass moisture content changing from 10% to 40% in weight and mass flow ratio of air to biomass from 1.1 to 2.3. Highest exergy efficiencies were achieved during gasification process. The equivalent coal mass flows of biomass at gasification optimum conditions were calculated and synthetic gas co-firing results were obtained too. Higher moisture content in biomass and more replacing coal ratio make theory flue gas volume flow and flue gas´ moisture content increase more greatly. It shows that impact of synthetic gas co-firing on boiler is not great when less than 5% coal is replaced or the moisture content in biomass is less than 10%.