By comparing the circulating fluidized bed(CFB) boiler with conventional pulverized coal(PC) boiler in steam parameters

heating surface arrangement and regulation approaches

it finds out that the combustion characteristics of CFB boilers are more suitable for secondary reheat technology using ultra-high parameters.The research results show that

the heat transfer temperature difference in CFB boiler furnace is lower than that in PC boiler furnace

but due to the large quantity of solid materials in CFB boiler furnace

the heat transfer coefficient and heat load of high temperature heating surfaces in the CFB boiler are higher than those in PC boiler.The uniformity of combustion in CFB boiler makes the deviation of steam temperature and wall temperature of high temperature and heating surfaces well controlled.The arrangement of secondary reheater in CFB boiler is more flexible

which can be arranged in the tail double-pass and external heat exchanger.Moreover

various heating surfaces

such as evaporative superheater and reheater

can be arranged in the outer loop of CFB

so the height of furnace can be reduced obviously

thus the cost of CFB boiler can be reduced.The CFB boiler has more flexible adjustment methods.By adjusting the mass concentration of gas-solid particles in furnace during operation

and combining with flue gas recirculation and flow regime reconstruction technology

it can regulate the heat load and steam temperature of the high temperature heating surfaces.