How is the flow of natural draft controlled in a boiler system?

The flow of natural draft in a boiler system is primarily controlled by dampers mounted in the breaching, which can be operated by automatic controls. This setup allows for precise regulation of airflow, which is crucial for maintaining optimal combustion conditions within the boiler.

The dampers enable adjustments to the resistance against the draft, influencing the amount of air that enters the furnace. By optimizing the airflow, the system can enhance combustion efficiency, reduce emissions, and improve overall system performance. Automatic controls add a layer of sophistication by allowing for real-time adjustments based on varying operational conditions, thereby ensuring that the combustion process remains stable and efficient.

Other methods mentioned, such as manually adjusting the furnace temperature or increasing the height of the stack, do not provide direct control over the draft flow in the boiler. Manual adjustments may not respond quickly enough to changing conditions, and while increasing stack height can enhance natural draft due to increased buoyancy, it is not a controllable mechanism in the same way that dampers are. Changing the type of fuel affects combustion characteristics but does not directly control the flow of natural draft.