How Does a CFB Boiler Work?

Circulating Fluidized Bed combustion has given boiler and power plant operators a greater flexibility in burning a wide range of coal and other fuels. All this without compromising efficiency and with reduced pollution. How does a CFB boiler work with this technology?In the old days, blacksmiths used to heat the iron by placing it on a bed of coal. Bellows provide air to the coal from the bottom of the bed. Fluidized Bed combustion is something similar to this.

Fluidized Bed
At the bottom of the boiler furnace there is a bed of inert material. Bed is where the coal or fuel spreads. Air supply is from under the bed at high pressure. This lifts the bed material and the coal particles and keeps it in suspension. The coal combustion takes place in this suspended condition. This is the Fluidized bed.
Special design of the air nozzles at the bottom of the bed allows air flow without clogging. Primary air fans provide the preheated Fluidizing air. Secondary air fans provide pre-heated Combustion air. Nozzles in the furnace walls at various levels distribute the Combustion air in the furnace.

Circulation
Fine particles of partly burned coal, ash and bed material are carried along with the flue gases to the upper areas of the furnace and then into a cyclone. In the cyclone the heavier particles separate from the gas and falls to the hopper of the cyclone. This returns to the furnace for recirculation. Hence the name Circulating Fluidized Bed combustion. The hot gases from the cyclone pass to the heat transfer surfaces and go out of the boiler.
Bed Material
To start with, the bed material is sand. Some portion is lost in the ash during the operation and this has to be made-up. In coal fired boilers the ash from the coal itself will be the makeup material. When firing bio fuels with very low ash content sand will be the makeup bed material. For high Sulphur coals Limestone addition to the bed material reduces SO2 emissions.
CFB Boiler Supplier
ZG Boiler is the CFB boiler supplier with 70 years’ history and ASME, PED, IBR, AS, GOST certifications, which are the guarantee of providing client products with rich experience, advanced technology, high quality, excellent service. Thanks to our efforts, we can design and manufacture oil & gas fired boiler, coal fired boiler, biomass fired boiler, CFB boiler, waste heat recovery boiler and industrial autoclave. If you have any need, you can contact our online service or leave a message on our website, we will contact you within 24 hours. 

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