What is the difference between fluidized bed boiler and common boiler?

Different combustion modes are the core difference between fluidized bed boiler and common boiler.

Fluidized bed boiler adopts fluidized combustion mode. After the fuel is crushed to a proper particle size by a crusher, it is fed from the upper part of the air distribution plate of the combustion chamber by a coal feeder, mixed with the hot boiling materials in the combustion chamber, heated rapidly, and the fuel quickly catches fire and burns. Under the action of high air velocity, a large number of solid particles are carried out of the combustion chamber. After being separated by a gas-solid separator, the separated materials are returned to the combustion chamber by a material return device to continue to participate in combustion.

Common boilers are fired by layers. The fuel enters the chain grate through the coal hopper, and enters the furnace with the movement of the chain grate to start its combustion process. Burned coal cinders are discharged to the slag discharge well at the tail of the chain grate with the movement of the chain grate. At the same time, there is air cooling under the chain, which can protect the grate from burning.

Structural and system differences between fluidized bed boiler and common boiler.

The difference of combustion mode leads to the difference of structure between fluidized bed boiler and common boiler. The main structure of circulating fluidized bed boiler includes combustion chamber and circulating furnace, starting burner, air chamber, air distribution device, furnace, gas-solid separator, material return device, drum, downcomer, water wall, superheater, economizer, air preheater, etc. In addition, the circulating fluidized bed boiler mainly includes blower, induced draft fan, return fan, crusher, coal feeder, slag cooler, dust collector, desulfurization and denitrification equipment, chimney, etc.

Common boilers include chain grate, water wall, steam drum, downcomer, superheater, etc. The system has no return fan and crusher.