In a travelling grate system, what percentage of the combustion air is typically fed from the bottom?

In a travelling grate system, the design and operation are specifically optimized to ensure efficient combustion of solid fuels, such as coal or biomass. Typically, a significant portion of the combustion air, often between 60% and 85%, is fed from the bottom of the grate. This bottom air supply plays a crucial role in supporting the combustion process by providing the necessary oxygen for the burning fuel on the grate.

Feeding air from the bottom allows for a more uniform combustion profile as it directs the airflow upwards through the fuel bed. This upward flow helps to facilitate the ignition of the fuel, enhance combustion efficiency, and minimize unburned carbon in the ash. It also helps in controlling the temperature profile within the combustion chamber, leading to more complete combustion and less emissions.

The remaining percentage of combustion air is usually supplied from other areas, such as the sides or top, contributing to the overall combustion process. Therefore, the choice indicating that 60% to 85% of the combustion air is fed from the bottom correctly reflects the operational characteristics and design principle of travelling grate systems.