Where is the continuous blowdown pipe located in a boiler?

The continuous blowdown pipe in a boiler is indeed located a few inches below the water level in the steam drum. This positioning is crucial because it allows the boiler to effectively remove a small amount of water continuously, which helps control the concentration of impurities in the boiler water. By taking blowdown water from just below the water line, it ensures that the water being expelled contains higher concentrations of dissolved solids and impurities, while retaining the cleaner water above.

This action is vital for maintaining water quality and boiler efficiency, as it minimizes the risks of scaling and corrosion, which can adversely affect the boiler's operation and longevity. The other choices do not appropriately capture the essential function and location of the continuous blowdown pipe in relation to the steam drum's design and water treatment requirements.