Study on low-load combustion characteristics of a 600 MW power plant boiler with self-sustaining internal combustion burners

To cope with the problems caused by the integration of new energy into the grid, self-sustaining internal combustion (SSIC) burners are introduced for flexible peaking of coal-fired units. However, there is still a lack of research on the combustion characteristics of power plant boilers utilizing SSIC burners under low load conditions. This paper presents a retrofit study of a boiler for low load by an SSIC burner with the aim of improving boiler combustion efficiency and reducing pollutant emissions. The combustion characteristics of a 600 MW power station boiler at 30 %-48 % of the maximum continuous rating (MCR) are analyzed by numerical simulation methods, and the effects of SSIC burner on the flow field, temperature distribution, NOx emission and thermal efficiency of the boiler are investigated. The results show that after the SSIC burner modification, the enhancement of flue gas jet rigidity improves the combustion stability. The pyrolysis gas concentration in the furnace is much higher than that of conventional combustion, which helps to reduce NOx. Pyrolysis gas and high- temperature char can promote combustion. When the boiler load is at 36 %-48 % MCR, the initial NOx emission is less than 50 mg/Nm3 and the emission standards are met by combustion alone. Initial NOx emission is reduced by 69 % at 30 % MCR. The thermal efficiency of the boiler increases by 2.96 % and 2.56 % at 36 % and 42 % MCR, respectively. The study shows that the SSIC burner can significantly improve the combustion stability of coal-fired units, reduce NOx emissions and improve the thermal efficiency of the boiler, which provides technical support for the low-load peaking of coal-fired power plants.