The two main ways to control surface blowdown in boilers are by conductivity sensors and manual valves. Conductivity sensors work by measuring the conductivity of the boiler water and then automatically blowing down dirty surface water for a set amount of time until it reaches the operator’s desired conductivity.
Manual valves work on a percentage principal. Boiler operators look at water quality and other operating conditions to come up with a percentage of surface water to continuously blowdown. This percentage is based on the boiler’s average steam production. The blowdown percent range needed can vary greatly depending on the boiler room conditions and the water available for boiling.[Read more…] about Controlling continuous boiler blowdown flow rate using heavy duty control valves: Madden’s Orifice Meter