Experimental and Numerical Simulation Research on Combustion and NOx Emission of Low Calorific Value and High-Alkaline Coal Based on Jet Characteristics of Flow Field

Abstract

A numerical model of a tower boiler burning low calorific value and high-alkali coal was established; based on the jet rigidity of the flow field in the furnace, the effects of air velocity and air volume flow on the combustion of high-alkali coal and NOx emissions were studied. The optimal parameters obtained by numerical simulation are applied to a typical experimental boiler. The experimental results show that when SOFA operates at about 65 m/s, the rigidity of the jet is obviously increased, the flow field and temperature field in the furnace are uniform, the temperature of the flue gas at the outlet is reduced by 53 K, the CO concentration at the furnace outlet was reduced from 3713 ppm to 57 ppm, the exhaust gas temperature was reduced by 6 K, and the concentration of NOx is reduced to 163 mg/m3. On the other hand, the combustion efficiency is increased by 0.86%, which translates into 2 g/kwh of standard coal, and the problem of easy coking has also been effectively solved. The collaborative optimization of high-alkali coal combustion and NOx emission is realized.