Study on the influence of the secondary air offset adjustment of the octagonal tangentially boiler on the deviation of the flue gas temperature

Abstract

Boilers using fan milling systems usually use octagonal tangential combustion. The angular combustion method of the burner with one angle in the longitudinal direction of each coal pulverizer can easily lead to partial burning of the flame and uneven heat load in the furnace, which in turn leads to deviations in the smoke temperature of the furnace and the temperature of the steam on the heating surface. Through the offset adjustment method of the secondary air at each corner, the combustion deviation can be adjusted more flexibly and quickly. In this paper, the influence law of a 660MW unit's boiler angle secondary air offset adjustment method on the deviation of furnace smoke temperature is studied. The experiment conclusions show that opening the secondary air in the main combustion zone at a certain corner will cause the furnace smoke temperature on the opposite side of the corner to rise, and the furnace smoke temperature on this side to decrease. Under medium and low loads, when the adjustment range of the secondary air damper in the main combustion zone is 15%, the flue gas temperature change range is above 10°C. Adjusting the SOFA wind has little effect on the change of smoke temperature, and the change of smoke temperature after 15% damper adjustment is 0∼5°C. Changing the flue gas flow direction through the over-burning air is not as effective as directly changing the tangent circle position produced by the main combustion zone.