What is the function of a boiler stack?

The function of a boiler stack is primarily to exhaust flue gases outside of the boiler system while simultaneously creating a draft that promotes efficient combustion within the furnace. This is accomplished through the principles of buoyancy and pressure differentials. When the hot flue gases rise in the stack, they create a negative pressure that helps draw in fresh air for combustion. This process is essential for maintaining proper air-to-fuel ratios, enhancing efficiency, and ensuring safe operation by preventing the accumulation of harmful gases within the boiler or the facility. The effective operation of a boiler stack is crucial for both performance and environmental compliance, as it helps to minimize the release of pollutants into the atmosphere.

In contrast, filtering flue gases, providing a pathway for steam, or supplying additional fuel are not functions of a boiler stack. Filtering would be more associated with specific environmental control devices, while steam circulation pertains to the steam side of the boiler and not the flue gas exit. Additional fuel supply is managed through separate fuel supply systems, not the stack itself.