What is one method used to maintain final steam temperature when loads are low?

Maintaining final steam temperature during low load conditions is crucial for ensuring efficiency and preventing issues like thermal fatigue. Gas recirculation is an effective method to achieve this by redistributing heat within the system.

When a boiler operates at low loads, it can lead to a situation where the steam temperature may drop due to insufficient heat transfer. By recirculating some of the flue gas back into the combustion process, you can increase the overall temperature of the combustion gases entering the boiler. This helps in maintaining the heat output and, consequently, the steam temperature, even when the load is not sufficient to produce the necessary heat through the regular combustion process alone.

This control mechanism not only helps maintain steam temperatures within desired limits but also improves the efficiency of fuel usage, minimizing emissions, and ensuring the boiler operates within safe thermal parameters.