Vacuum Breaker

Vacuum Breaker for Reducing the Running Down Time of the Turbine

Function

• With normal shut down or tripping of the machine, the function of the vacuum breakers is to cause an increase in condenser pressure by conducting atmospheric air into the condenser together with bypass steam flowing into the condenser from the bypass station. 
• When the pressure in the condenser increases, the ventilation of the turbine blading is increased, which causes the turbo set to slow down so that the running down time of the turbo set and the time needed for passing through critical speeds are shortened.

Mode of Operation of Vacuum Breaker

• When the magnet is not excited, the solenoid valve is switched to open. 
• The control medium arising holds the vacuum breaker valve in the closed position by means of the power piston. 
• When the pressure drops the vacuum breaker is opened by spring force.

Opening Process

• When the magnet is excited the control medium is without pressure so that the control medium in front of the solenoid valve is connected with the drain ‘c’. The piston (3) and thus the valve disc (19) are moved upwards by the force of the spring (5) (Fig. 2).

Closing Process

• When the magnet is not excited the valve is closed by the control medium arising. The pressure of the control medium ‘a’ via the piston (3) presses seal ring (17) arranged in the valve disc (19) on to the valve seat (20) against the force of the compression spring (5).