What kinds of heat exchangers are commonly used in circulating fluidized bed boilers?

　　There are several types of heat exchangers, such as surface type, hybrid type and heat storage type.

　　The hot and cold fluids flow inside and outside the heat exchanger wall respectively, and exchange heat through the tube wall, and the fluids themselves do not mix with each other. This kind of heat exchanger is called a surface heat exchanger. Most of the heating surfaces of circulating fluidized bed boilers are surface heat exchangers.

　　The hot and cold fluids are mixed with each other, and the mass is also mixed with the heat exchange. This kind of heat exchanger is called a hybrid heat exchanger. The water spray desuperheater of the circulating fluidized bed boiler is a hybrid heat exchanger.

　　The heat exchanger in which the cold and hot fluid alternately passes through the heat storage components to exchange heat is called the regenerative heat exchanger. The rotary air preheater used in the circulating fluidized bed boiler belongs to the regenerative heat exchanger.