Explain how a feedforward control system improves combustion stability in a biomass boiler.

A feedforward control system improves combustion stability in a biomass boiler by anticipating and proactively compensating for disturbances before they significantly affect the boiler's operation. Unlike feedback control, which reacts to changes in the controlled variable (e.g., steam pressure), feedforward control measures disturbances directly and adjusts the manipulated variables (e.g., fuel feed rate, air flow rate) accordingly. In a biomass boiler, common disturbances include variations in fuel heating value, moisture content, and feed rate. A feedforward system measures these disturbances using sensors and then calculates the necessary adjustments to maintain a stable combustion process. For example, if the heating value of the biomass fuel decreases, the feedforward control system will increase the fuel feed rate to compensate for the lower energy content, maintaining a consistent heat input to the boiler. Similarly, if the fuel moisture content increases, the system will adjust the airflow to ensure adequate combustion and prevent quenching of the flame. By taking preemptive action, the feedforward control system reduces the magnitude and duration of deviations from the desired operating conditions. This results in more stable steam pressure, consistent combustion temperatures, and reduced emissions. The combination of feedforward and feedback control provides the best combustion stability. The feedforward part addresses expected disturbances, while the feedback part corrects for any remaining deviations, leading to a more reliable and efficient boiler operation.