Swing Check Valve (Cold reheat steam line)

Swing Check Valve

• In order that the turbine may be completely separated from the steam when it is stationary, an additional check valve LBC10 AA001 is fitted in the line between the HP cylinder and the reheater and operating through pilot valve MAX42AA001 +002 and the rotary actuator KA01 depending on the pressure in the associated secondary medium circuit. 
• The swing check valve opens fully when the control valves reached approx. 5 to 10% of their full-power travel. 
• Only when the control valves reach this point again as they are being closed, the swing check valve brought into steam flow again by the hydraulic actuator. 
• Thus when the steam flow in the normal direction ceases, the check valve is closed by the actuator KA01 and prevent the steam in the cold reheat line from returning to the turbine. 
• By removing the valve from the steam flow during operation above 5 to 10% of maximum power, additional pressure losses during normal operation are avoided. 
• If, during start-up, the steam pressure on the inlet side of the valve and at the same time the secondary medium pressure is not yet sufficient to open the valve, the steam pressure will open the swing check valve against the medium pressure in the manner of a safety valve. 
• The Open and Control position of the swing check valve are indicated in the control room via the limit switches.