Research on Optimization of Flow Field and Combustion Performance in Boilers With Combined Near‐Wall Air Supply Systems

ABSTRACT In the pulverized coal boiler industry, reducing NO x emissions has become a critical objective. Although low‐NO x combustion technologies are effective, they may lead to localized high‐temperature corrosion. To address this issue, near‐wall air supply technology has been introduced, which involves injecting an appropriate amount of air near the furnace walls to form a protective oxidizing layer, thereby diluting fuel concentration to prevent the formation of localized hot spots and preventing reductive gases from contacting water‐cooled walls, thus reducing the deposition of corrosive materials. This study innovatively proposes the concept of a combined near‐wall air supply system, designing three layout forms—square, crisscross, and triangular configurations—based on different application scenarios, and adjusts the positions of nozzles on the front, rear, left, and right walls as well as the jet velocities to evaluate their impact on the boiler's combustion characteristics. Simulation results show that with a crisscross configuration and nozzles installed on all four walls, combined with a jet velocity of 5 m/s, the most effective promotion of uniform temperature distribution can be achieved, avoiding material failure due to localized overheating and enhancing overall combustion efficiency. This approach not only reduces NO x emissions by approximately 10% but also decreases the concentration of reductive atmospheres that cause high‐temperature corrosion. This demonstrates that the optimized near‐wall air supply system significantly improves boiler performance.