This paper describes the numerical and experimental investigations of the gas temperature deviation in the crossover pass of a large scale, advanced low NOx, tangentially fired pulverized coal boiler. Major attention was paid to the region of the final super-heater where the tube ruptures occasionally had been occurred due to the tube overheating. Computational Fluid Dynamics (CFD) simulation and measurements of gas temperature just in front of the final super-heater showed the gas temperature distribution was biased to the left, lower region of that heater. It was found that this deviation is originated from the residual swirl flow in the upper furnace. To alleviate the gas temperature deviation, the changes in yaw angles of over-fire air have been suggested and the field tests carried out to identify their effects on that deviation. The test showed it is quite effective method to reduce that deviation. (C) 2012 Elsevier Ltd. All rights reserved.