Abstract: The cooling wind of the dry slagging system will affect the burning organization in the furnace. The existing research mostly adopts the field test method, and the research object is mostly the exhaust gas temperature or the boiler efficiency. Taking a 660 MW supercritical unit of a wet slag machine to dry slag machine as the research object, the influence of air leakage from dry slag machine on combustion and NO_x emission characteristics of the furnace was studied by numerical simulation method. At the source, changes in key parameters such as furnace flame center, fly ash carbon content, and NO_x emission concentration. The results show that the air leakage at the bottom of the furnace is the same as that of the burned-out wind. The influence of the air leakage at the bottom of the furnace is not obvious. When the air leakage at the bottom of the furnace is all or part of the secondary air reduction of the burner, the air leakage accounts for the secondary air. As the proportion increases, the oxygen level in the main combustion zone, the carbon content of the outlet fly ash, and the NO_x emission concentration increase accordingly. From the perspective of the cooling air volume on the combustion and NO_x emission characteristics of the furnace, the influence of different cooling air sources of the dry slag machine on the unit operation is analyzed, which provides theoretical guidance for the design, modification and operation of the dry slag discharge machine.

Key words: pulverized coal combustion, bottom leakage, dry slag discharge, numerical simulation