Numerical simulation of biomass grate furnace combustion based on FLIC

Abstract:

Based on the FLIC simulation platform, we have performed a numerical simulation study on a 7 MW biomass layer fired hot air boiler in Northeast China. The simulation results show that the biomass layer can be roughly divided into three stages, the water evaporation section (0~0.5 m), the volatile emission combustion section (0.5~2.1 m) and the fixed carbon combustion section (1.0~2.8 m). The volatile content of this fuel is relatively high, the thickness of the bed after its precipitation is significantly reduced, and the primary air temperature is too low, resulting in a low fixed carbon burnout rate, so the primary air temperature can be appropriately increased. According to the characteristics of the fuel in different combustion stages, the air can be supplied on demand. For example, 80% to 90% of the total volume can be provided during the volatiles escape combustion stage, and 10% to 20% of the total air can be provided during the fixed carbon combustion stage. This improves the fuel combustion efficiency, and can optimize the structure of the arch angle and the furnace arch coverage length according to the flue gas temperature, and enhance the ignition and burnout of the furnace arch. According to the simulation results, it is proposed to optimize the primary air and the air supply scheme to make the combustion more adequate.