In order to study the effect of the vertical swing angle of the re-burning nozzles on the combustion characteristics of a pulverized coal coupled biomass gas re-burning system

Based on Fluent simulation software to build a biomass gas reburning boiler model

a power plant 600 MW coal-fired boiler coupled with two 20 t/h straw gasifier re-burning systems was used to carry out numerical simulation of the combustion process in five cases including the swing angle of the re-burning nozzles is 0°

±15°

and ±25°

respectively

analyze the distribution characteristics of the velocity field and temperature field of the flue gas at the combustion zone

the folding angle and the furnace outlet. The results show that the temperature change trend of the combustion zone in the furnace is roughly the same under the cases of biomass gas re-burning. Changing the vertical swing angle of the reburning air nozzle will affect the combustion stability in the furnace

when the downward swing angle of the reburning air nozzle is too large（case 1）

the reburning air flow will disturb the flue gas flow in the main combustion zone and affect the combustion of pulverized coal in the main combustion zone. With the upward tilt of the re-burning nozzles swing angle

the flue gas temperature deviation at the furnace outlet and the uneven temperature distribution coefficient gradually increase

when the re-burning nozzles swing angle is +25°（case 4）

the M value is the largest

reaching5.80%. While not affecting the combustion of the main combustion zone in the furnace

when the re-burning nozzles swing angle is-15°

the flue gas temperature deviation at the furnace outlet is the smallest. The swing angle of the reburning nozzle is inclined downward to a certain angle

which is beneficial to reduce the thermal deviation of the furnace outlet.