Studies on heat flux distribution on the membrane walls in a 600 MW supercritical arch-fired boiler

Abstract

The heat flux distributions on the membrane walls in the furnace of a 600MW supercritical arch-fired boiler (SC-AFB) were studied by numerical simulation and field measurements. The results revealed that on the front and rear walls, the horizontal heat flux profiles in the upper furnace exhibit an M-shaped pattern. At full boiler load, on the front wall the distance between two peaks is about half of the furnace width around the conjunction area of the upper and lower furnaces and it decreases as the furnace height increases. While on the rear wall, the two high heat flux zones on each half wall nearly merge and the distance between the two peaks is about 1/3 of the boiler width. As boiler load decreases, the heat flux is smaller and distribution becomes more uniform. At all loads, on the side walls, the profiles are only in bell-shaped. The predicted heat flux distributions are in good agreement in trend and value with the measurement data. Numerical simulation also revealed that the M-shaped heat flux distribution is a special feature of an AFB/SC-AFB whose furnace has a rectangular horizontal cross section with a large width/depth ratio. Some suggestions are provided to improve the aerodynamics field and combustion in the SC-AFBs.