Numerical Modeling of Biomass Gas Co-firing Process and Combustion Analysis in a 300MW Pulverized Coal Boiler

A biomass gas co-firing model for analysis of combustion characteristics and flue gas features in a pulverized coal boiler is proposed in which the biomass gas co-firing ratio changes from 0% to 20%. The furnace temperature decreases gradually with the increase of co-firing ratio when the biomass gas is injected through the lowest primary air layer burner. The mean temperatures at the furnace center and at the furnace outlet are reduced gradually with the increase of the co-firing ratio, and the temperature difference between 0% and 20% co-firing cases can reach more than about 250K, which can contribute to the NOx decrease for co-firing cases. The results showed that the mean CO concentration distribution increases and the mean NO concentration decreases at co-firing cases compared with the coal fired only case along the height of furnace. The best co-firing ratio should be determined in detail because both the furnace temperature and the biomass gas features can influence the co-firing results.