The research work for several forward tasks in technical sector of circulating fluidized bed (CFB) boilers has been analysed and summarized. The key for developing 200 MW and larger CFB boilers is to research and develop externally positioned heat exchanger. For this

the Xi’an Thermal Power Research Institute Co Ltd has developed a pattened technology of splitting type returning ash heat exchanger. Taking this technology as a basis

the design ideology of “composite boiler type” and its scheme have been put forward. The 200 MW CFB boiler can be designed to use two types of configuration

i.e. H or M type of layout

and can be scaled up to 300 MW. Since supercritical CFB boiler can simutaneously realize high efficiency and clean combustion

being the inexorable trend of technical development for CFB boilers

and then the key technologies for developing 600 MW CFB boiler being analysed.