Abstract: Numerical simulation was taken on a 75 t/h pulverized coal boiler in a power plant，to study the effect of its synergistic control on air staging and flue gas circulation on its combustion characteristics in furnace and NOx emission.The modeling results show that the temperature and CO volume fraction at the furnace outlet rise with the increase of SOFA rate，while the NOx mass concentration drops.And with the increase of flue gas circulation rate，the oxygen volume fraction in the secondary air to furnace declines，yet the denitration efficiency goes up.When the flue gas circulation rate exceeds 15%，the combustion stability will be affected.Synergistic control on air staging and flue gas circulation can make the furnace temperature distribute evenly along furnace height.Having taken the optimized scheme（SOFA rate=25%，flue gas circulation rate=15%），the efficiency of synergistic denitration reaches 61% without prominent effect on the CO volume fraction at furnace outlet.It shows that this optimized scheme can lead to a better low-nitrogen combustion with a decent burn-out rate.The research results have certain theoretical guiding significance for the precise control on denitration of pulverized coal boilers.

Key words: air staging, flue gas circulation, low-nitrogen combustion, numerical simulation, denitration