What is the maximum ash content of a fuel that can successfully burn in a fluidized bed combustion (FBC) unit?

In fluidized bed combustion (FBC) systems, the maximum ash content of the fuel is a critical factor in ensuring efficient combustion and preventing operational issues. Fluidized bed technology is designed to handle fuels with high ash content because the bed of solid particles can support and disperse the ash, allowing for effective combustion at lower temperatures.

The technology can tolerate a significant amount of ash because the fluidized state helps to minimize issues like slagging and fouling that are typically observed in other combustion systems with lower ash content. With an ash content of up to 70%, FBC units can maintain a stable combustion process while efficiently utilizing the fuel. The high turbulence and mixing in the bed can also help in the complete combustion of such fuels.

As ash content increases beyond this threshold, operational challenges such as excessive bed agglomeration, reduced heat transfer, and difficulty in controlling combustion efficiency may arise. Hence, the maximum ash content of 70% reflects the upper practical limit for efficient and reliable operation of fluidized bed combustion systems.