Main Components of a Circulating Fluidized Bed Boiler
A circulating fluidized bed (CFB) boiler primarily consists of three key systems: the combustion system, gas-solid separation and circulation system, and convection flue system.
- Combustion system: This includes the air chamber, air distribution plate, combustion chamber, furnace, fuel oil, and coal feeding systems.
- Gas-solid separation and circulation system: This system is composed of a material separation device and a return material device.
- Convection flue system: This includes heat exchange surfaces such as the superheater, reheater (if applicable), economizer, and air preheater.
These components work together to achieve efficient combustion and heat transfer, optimizing the boiler’s performance.
CFB Boiler’s Three Combustion Zones:
- Dense Phase Zone (Lower Furnace)
- Dilute Phase Zone (Upper Furnace)
- High-Temperature Gas-Solid Separation Zone
These zones collaborate to facilitate combustion and heat transfer, ensuring the boiler’s efficient operation.
The reason why smaller coal particles ignite more easily than larger ones
Smaller coal particles ignite more easily because they have a larger surface area in contact with oxygen per unit mass. Additionally, at the same fluidization velocity, smaller particles move more actively, enhancing heat and mass transfer processes. They have more opportunities to exchange heat with hot materials, leading to a quicker temperature rise. As a result, smaller particles ignite faster than larger ones.
Factors influence the thermal efficiency of a CFB boiler
- Fuel characteristics: The size, composition, and calorific value of the fuel affect combustion efficiency. High moisture or large particles reduce thermal efficiency.
- Combustion temperature: The ideal combustion temperature is between 800°C and 900°C. Too high or low temperatures lower combustion efficiency.
- Excess air coefficient: A proper excess air coefficient ensures enough oxygen for combustion. Too much air, however, removes heat and reduces efficiency.
- Circulation rate of bed particles: The particle circulation rate affects thermal efficiency. High circulation ensures even combustion but also raises energy use.
- Flue gas temperature: High flue gas temperatures indicate heat loss. The elliptical tube air preheater launched by Bokk Tech can lower the flue gas temperature to reduce heat loss and improves efficiency.
About Us
Shandong Bokk Tech is dedicated to solve the problem such as ash blockage, corrosion and excessive exhaust gas temperature in the tubular air preheater of small and medium-sized boilers. We primarily manufacture automatic cleaning devices for tubular air preheaters and corrosion-resistant heat pipes. Our products are widely used in the thermal power plants, chemical plants, new energy sector, etc.
We offer customized services to customers around the world, allowing us to adjust product dimensions and other specifications based on your specific needs, to improve air preheater heat efficiency.
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