Which of the following is a step in the flow of a Circulating Fluidized Bed (CFB)?

In the context of a Circulating Fluidized Bed (CFB) system, the correct choice reflects the operational sequence and functions crucial for efficient combustion and energy recovery.

When gases pass through superheaters and economizers before entering a mechanical dust collector, they undergo important processes that enhance overall thermal efficiency. The superheaters raise the temperature of the flue gases, which is essential for optimizing heat transfer and improving the efficiency of the subsequent turbines or heat recovery systems. Economizers utilize the heat from the flue gases to preheat feedwater before it enters the boiler, further increasing thermal efficiency.

This step is integral to controlling emissions and recovering energy, making it a fundamental part of the CFB process. By enhancing combustion efficiency and minimizing waste, this operational flow directly supports the performance goals of CFB technology, which is designed to burn fuel cleanly and effectively while minimizing the environmental footprint.

The other options do not represent typical or efficient operations within a CFB system, as they either describe processes not aligned with standard practices in CFB technology or suggest inefficient practices that would not be feasible in a well-designed system.