Experiment and Numerical Simulation Study of Low-nitrogen Combustion Technology inside Small Gas Boiler

This paper studies different experimental conditions for a 25t/h industrial boiler fueled with nature gas. In the meanwhile, numerical simulation is carried out using the commercial software of Fluent. The different excess air coefficient of 1.05,1.1,1.15,1.2 and 1.25 are studied. The different flue gas circulation rate of 5%,10%,15% and 20% are studied compared with that rate of 0. The results show that the maximum temperature of the furnace and NOx emission concentration at the outlet increase firstly and then decrease with increasing of excess air coefficient when flue gas circulation rate is 0, and the peak value of temperature and NOx emission concentration reaches to 2071.93K and 65.21mg/m3 when excess air coefficient is 1.15, respectively. With increasing of flue gas circulation rate, the average temperature of the furnace and the concentration of NOx at the outlet decrease, the concentration of NOx decrease from 65.21mg/m3 to 25mg/m3. The higher of the flue gas circulation, the smaller of the high temperature area of the furnace and the lower concentration of O2. However, excessively higher flue gas circulation rate and excess air coefficient can lead to incomplete combustion and lower coefficient. Hence, for optimizing the combustion conditions, the excess air coefficient and the flue gas circulation rate should be within an appropriate range.