Calculation and analysis of dissipation heat loss in large-scale circulating fluidized bed boilers

In the present work, experimental studies of dissipation heat loss were carried out on two types of 300 MWe circulating fluidized bed (CFB) boilers. Results indicated that there was great difference of dissipation heat loss between the two types of CFB boilers. Under the full work load, one boiler's dissipation heat loss was more than twice as that of another. The difference of dissipation heat loss between the boilers was mainly from differences of heat dissipating capacities in cyclones. Compared with steam cooled cyclone, there was much more heat dissipating from hot cyclone to the surroundings for the hot cyclone has a relatively higher surface temperature and larger surface area. Since the existing empirical curves cannot fully reflect the difference, it is inclined to calculate the heat loss according to test codes issued by ASME or EPRI. In order to reduce the large amount of measurements, a simplified suggestion was introduced and results showed the matching between the simple method and measurements was good.