Numerical Simulation Of Reburning Of Biomass Gas In 600MW Supercritical W-Type Flame Boiler

Biomass is a clean renewable energy source that does not contain nitrogen oxides.The use of biomass gas obtained by biomass gasification to replace a part of coal powder as a reburning fuel for combustion can save energy and reduce pollutant emissions.In this paper,using the method of numerical simulation,based on biomass gas reburning technology,a simulation study and thermal calculation of coal-fired and reburning conditions of a 600 MW supercritical W-type flame boiler in China under different loads are carried out,it aims to provide a technical support for boiler energy-saving renovation.The main conclusions are as follows:(1)Comparing the reburning conditions under the same load with the conventional coal burning conditions,the velocity field and temperature field at the lower furnace are not changed much,and the overall temperature of the upper furnace is increased.Under the rated load,the maximum temperature of the furnace in pure coal combustion conditions is 41 °C higher than that of the reburning condition,and the area where the upper furnace is injected into the biomass gas is 33 °C higher than the maximum temperature of the lower furnace section.(2)Under reburning conditions,the CO concentration in the biomass gas vent area is suddenly increased,which is much larger than the CO produced when the pulverized coal in the lower furnace is insufficient to burn oxygen.Then the CO reacts quickly and the CO concentration at the outlet is zero.(3)Under the reburning condition,the NO emission decreased significantly on the basis of the original.The NO concentration decreased by 23.8% under the rated load,the NO concentration decreased by 23.1% under the 75% load,and the NO concentration decreased by 22.7% under the 50% load.(4)Based on the segmental thermal calculation,the temperature distribution under reburning conditions is obtained.At the main combustion zone of the lower furnace,the highest temperature of the reburning condition is 54 °C lower than that of the pure coal combustion condition;in the upper gas zone of the furnace,the reburning condition is 70 °C higher than that of the pure coal combustion condition.Comparing the results of numerical simulations,the trend of temperature changes is the same,which proves the reliability of the conclusion.