Lp Bypass unit

         Having learnt about the importance of Hpbypass unit in the last post. Today let us know the importance of the LPBypass unit. Lpbypass unit bypasses the reheated steam from entering into the IP turbine by bypassing the steam directly into the condenser. Like HPBypass it also has main control valve, spray control valve and oil supply unit. Along with these it also has Isolation valve or stop valve which is not present in the HPBypass system as the Emergency stop valve serves the purpose in the HPBypass system.

       The LPBypass unit is important during the shutdown and the startup of the thermal power plant. Steam from the Hpbypass system eneters the CRH line and gets reheated in the boiler section and gets back to turbnie which is bypassed by the LPBypass unit directly into the condenser. Unlike HPBypass we must take much care in the LPbypass unit as the steam is directly sent to condenser the condenser wall temperatures will raise and the spray control valves must operate properly and timely manner to save the condenser if this is not maintained the system will stop the steam from entering to condenser by closing the stop valves to protect the condenser.

       The lbbypass valves cannot be opened directly during the cold startup as the temperature of the valves and the steam do not match and may result in the line hammering. So initially the lpbypass line is warmed up through warmup lines and they remain until the lpbypass lines has sufficient temperatures. 

       Here the LPBypass oil unit is used to supply the oil to the control valves and stop valves for proper operation.

 Thanks all