Continuous surface blowdown

What is the continuous surface blowdown in a steam boiler?

In a steam boiler, the concentration of dissolved solids in the boiler water increases during continuous boiling. The salt concentration of the boiler water must remain within specified limits to prevent scale formation, boiler water foaming, and salts from entering the steam system.

Surface blowdown is used to remove salts from the surface of the boiler water either automatically by monitoring conductivity or manually by determining the correct blowing quantity.

Selection of the surface blowdown valve

GESTRA surface blowdown valves with stepped nozzles are designed to remove salts from the surface of the boiler water, providing a durable and effective solution.

The continuous discharge blowdown valve (JUP valve) must operate under high differential pressure, which quickly destroys a normal control valve even if hardened shut-off surfaces are used. GESTRA manufactures valves designed for this application with stepped nozzles, in which the pressure is reduced in 3–4 stages. For large flow rates, a stepped nozzle, familiar from GESTRA’s high-pressure regulation valves, is used. Surface blowdown valves equipped with a manual lever have a clearly marked scale to ensure proper flow.