Study on the impact of near-wall air systems' wind speed variations on the combustion characteristics in coal-fired boilers

With increasingly strict national energy policies mandating ultra-low emissions for coal-fired power plants, the issue of high temperature corrosion caused by reductive gases and elevated furnace temperatures has become critical. This study proposes the implementation of near-wall air systems on both sides of mid-furnace burners to mitigate water-cooled wall corrosion and enhance combustion efficiency. Using numerical simulation, the effects of a near-wall air system with a wind speed of 20 m/s were analyzed across the entire furnace. Results show that this approach reduces the average near-wall temperature by 4%, while increasing O₂ concentration in the combustion zone by approximately 6%, thus promoting more efficient combustion. Additionally, CO₂ and CO concentrations decrease by about 4.5% and 5.9%, respectively, effectively reducing reductive gases and alleviating high-temperature corrosion. The NOx decreased significantly by 18.7%, indicating that air classification effectively suppressed NOx, which is a sign of efficient and low-nitrogen combustion. These findings offer a practical solution for improving boiler operational safety and efficiency under ultra-low emission requirements.