HP Bypass unit

Hi,

         Hpbypass unit is the important area in thermal power plant where the steam from the main steam line can be provided an alternative path to enter the CRH line bypassing the steam from entering the turbine. As this is directly connected to main steam line the pressure present is very high.

           This unit is very helpful when the system is started up and while the system is being shutdown, because under these conditions the parameters for enetering the turbine will not be met. HPBypass unit works in normal mode and fast open mode. Fast open mode is in service when boiler is in live condition and turbine alone trips to momentarily bypass the steam from entering the turbine the valves will open in a small time and stay for 3-5 sec in complete open or 100% open after that gets back to normal condition.

          The operation of the HPbypass unit is done via Hydraulic oil unit which supplies the control oil for proper valve operation. The HPbypass unit also contains the spray station which supplies spray water to cool down the high temperatures in the line. These valves operate on the oil pressure supplied to them as these are very important valves.

The hpbypass line normally opens in the unit shut down and unit start up period, but during the operation if  pressure crosses the set point defined, then the valve will open to down the pressure.

Also view LPBYPASS