Welcome to Boilersmith, Canada's Boiler Maker. The purpose of boiler blowdown is to regulate the amount of total solids, dissolved and suspended, contained in the boiler water. Added feedwater carries dissolved solids that are left behind in the boiler as it is evaporated.
Chemicals also add to the solids concentration.
Since evaporation is continuous, the accumulation is also continuous. Failure to remove sediments and sludge accumulation may result in premature boiler failure such as cracked boiler plates, low water cutoff failures or pressure controller failure. Failure to control dissolved and suspended solids in the boiler water may result in foaming and priming. This in turn results in a wetter steam and poor fuel economy. Steam boilers used solely for heating and where practically all of the condensate is returned to the boiler, blowdown only as often as the concentration of solids require.