Effects of Coal Blending and Operating Conditions on Combustion and NOx Emission Characteristics in a Tangentially-fired Utility Boiler☆

The influences of operating conditions, such as excess air ratio and SOFA arrangement, on temperature distributions, species distributions, NOx emissions and burnout of a tangentially-fired utility boiler using bituminous and blended coal were investigated by numerical approach in the present study. The simulation results show that the fuel type exhibits certain effect on the temperature distributions and the NOx emissions. Moreover, higher excess air ratio could restrain the CO formation but promote NOx emission. The temperature and the species distributions are highly related to the SOFA arrangement. In addition, SOFA technology is still an effective approach to control the NOx emissions during blended coal combustion, while the disadvantageous effect on char burnout should be considered. (C) 2017 The Authors. Published by Elsevier Ltd.