What is the purpose of boiler blowdown?

Boiler blowdown is a crucial procedure that involves the removal of a portion of water from a boiler to eliminate sludge, sediment, and dissolved impurities that can accumulate over time. As water in a boiler heats up and steam is generated, certain contaminants, such as minerals and organic matter, can concentrate in the remaining water. If not managed, these impurities can lead to problems such as scale buildup on the heat transfer surfaces, which decreases efficiency and can cause overheating or damage to the boiler.

By executing blowdown, operators can maintain water quality and ensure that the boiler operates safely and efficiently. Regular blowdown minimizes the risk of corrosion, scaling, and other operational issues related to water quality in a steam system. This practice is particularly important in high-pressure boilers where the consequences of impurities can be more significant.

The other choices do not accurately reflect the purpose of blowdown: injecting chemicals into the water pertains to treatment rather than maintenance, providing additional steam pressure is not a direct result of blowdown, and recycling steam back into the system does not address the need for removing impurities. Thus, the primary and essential purpose of blowdown is indeed to remove sludge and impurities.