Analysis on model selection of combustion mode for ultra-supercritical boiler

With the development of low-carbon economy and the capacity increase of ultra-supercritical units, the optimization design of boiler furnace structure and scientific selection of combustion mode are seriously technical problems in the power industry. This paper makes analysis and provides the resolution scheme for the problems aiming at the three main combustion modes of pulverized coal boiler, thus tangential circle firing, opposed wall firing and “W-shaped flame firing”, in the process of boiler scaling-up development, besides, makes the analysis of the three main combustion modes and combined with coal quality and factors existing in the overall layout of Π-type boiler and tower layout programs, discusses the of the selection principles for 600MW and 1000MW ultra-supercritical units. The main problems in the process of boiler scaling-up development includes heat deviation increase caused by the burner arrangement and the regulation of aspect ratio caused by the boiler capacity increase, and the resolution scheme of mixed arrangement of tangential oval and opposed wall has great advantages in the opposed wall firing of ultra-supercritical units using sliding-parameter operating and adapting spiral tube water wall. Combustion mode selection of pulverized coal boiler mainly depends on coal characteristics and thermal characteristics parameter of furnace, meanwhile it is also related to the milling system, the burner, the performance design and arrangement of air-distribution device, the coal fineness, the air temperature and the air distribution condition. The choice of combustion mode of ultra-supercritical units isn't also invariable, but the cooperation of tower layout and four comer tangential circle combustion modes is the ideal choice to wholly resolve the gas heat deviation for ultra-supercritical units. With the further research of tower layout with eight-square double tangential circle and the theory of Π-type with tangential oval combustion mode, the technical problem of combustion mode selection of ultra-supercritical units will be radically resolved, and the scientific selection of combustion mode will cooperate with the energy saving and emission reduction of boilers.