Continuous Blowdown System

Boiler water contains a significant amount of dissolved solids. As the boiler water evaporates, the dissolved solids do not evaporate – they are left behind. Therefore, the concentration of dissolved solids in the boiler water keeps on increasing.

Excessive amount of dissolved solids create foam, which increases entrainment of water droplets as steam leaves the water surface. Eventually, this results in carryover of water with steam into the superheaters tubes. Since temperature is far greater in the superheaters, the water droplets evaporate rapidly and shed their impurities as scale. In an earlier discussion we learned that scale can cause severe overheating and tube failure.