Wilson boiler blowdown systems are built around the Wilson centrifugal blowdown separator. The boiler blowoff is piped tangentially into the separator. In the resulting vortex the pressure is released, allowing the steam flash to rise through the vent while the water and sludge fall though the drain. A stainless steel heat plate protects agains erosion in the blowoff entry area. No water is retained in the separator.
Wilson separators are sized according to boiler operating pressure and blowoff valve size. These are the only two factors that determine the rate of flow to the separator. Vents are sized to keep internal flash pressures to a maximum of 5 psi as recommended by the National Board of boiler and pressure vessel inspectors and as required by some state and municipal code authorities. The drains sized for flow of blowdown effluent plus aftercooler water for maximum temperature 140F to sewer.
ASME design pressure of the separator should equal a minimum of 25% of the boiler maximum allowable working pressures (mawp) as recommended by the National Board.
Most codes covering this type of equipment should equal a minimum temperature limitation on wastes entering public sewers. Anti-pollution laws, which are widespread and universal, also include temperature limits for discharge to sewers and public waters. The Wilson aftercooler, properly sized for conditions, efficiently takes care of this problem.
Wilson equipment designed for hot water relief valve service is widely used for most economical and efficient disposal of relief valve discharge.