What temperature range needs to be achieved in a fluidized bed boiler for burning coal?

In a fluidized bed boiler, the temperature range of 450-500 degrees Celsius is optimal for coal combustion. This range allows for efficient burning of the coal while minimizing the formation of pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx).

The fluidized bed combustion process involves maintaining a bed of solid particles, such as sand or ash, in a suspended state by blowing air through the material. At temperatures around 450-500 degrees Celsius, solid particles are heated sufficiently to facilitate uniform combustion of the coal particles that are injected into the bed. This temperature range also helps in achieving a stable operation of the fluidized bed, ensuring that the coal is effectively activated for combustion while also controlling emissions.

Coal requires certain thermal conditions to achieve ignition and subsequent combustion; if the temperature is too low, the coal will not ignite properly, leading to incomplete combustion and increased emissions. In contrast, temperatures beyond this specified range can lead to excessive slagging and fouling, which can negatively affect the operation of the boiler. Thus, maintaining the combustion temperature within this range allows for optimal fuel efficiency and effective control of environmental impacts associated with burning coal.