Numerical simulation and engineering practice of a 670 t/h corner tangential boiler with reverse-tangent and swirling-elimination

With the 670 t/h corner tangential boiler serving an object of study, reverse-tangent cases at tertiary air and OFA (Over flow air) were performed by using combustion numerical simulation program. The studying results indicates: the revolution of in-furnace flow field is weakened because of the reverse-tangent of tertiary air, the relative diameter of the tangential circle and the full extent of flame in the furnace decreased at reverse-tangent layers, and the mixing intensity of gases changes little, which has little influence to in-furnace aerodynamic field. Analyzing temperature field and oxygen concentration field, in-furnace distribution of gas temperature improves after retrofitting that has little influence to major combustion zone, and high temperature area on wall reduces, which reduces the possibility of slagging. Temperature deviation of horizontal flue inlet is reduced, the residual rotation is weakened, uniformity coefficient of flue gas velocity decreases, and cross-section mean temperature changes little, which has little influence to heat transfer of heating surface. Engineering practice indicates: numerical experiment result is in conformity with real operation condition, and the retrofitting can effectively weaken the residual rotation and improve the distribution of flue gas temperature, which settles the problem of outlet temperature deviation that exists in corner tangential boiler.