The influence of flue gas recirculation on heat transfer along height direction of the furnace of the double-reheat tower furnace was discussed. Through programing

thermal calculation of the furnace multi-section of double-reheat tower boiler furnace in an ultra-supercritical 1 000 MW unit under different flue gas recirculation schemes was realized. The results show that

the flue gas recirculation will reduce the temperature at outlet of each section of the furnace. With an increase in unit load and the recycling ratio

the temperature drop increases. When the flue gas is introduced to the bottom of the furnace

the flue gas temperature in burner zone decreases significantly. As the height increases

the temperature drop at each section decreases

the furnace outlet temperature decreases slightly

and the radiation heat transfer in the furnace declined significantly

so the ratio of convective heat transfer to radiation heat transfer can be changed to regulate the reheat steam temperature. When the flue gas is introduced into the upper part of the furnace

the temperature drop at the flue gas inlet section is the largest

and the temperature at the furnace outlet decreases obviously. The radiation heat transfer in the furnace reduced little

which helps to ease the slagging at the furnace outlet

but cannot regulate the reheat steam temperature.