UV / SV Preheater Bypass System

While in normal operation the feed water enters the inlet valve (UV), passes through the preheater and exits through the outlet valve (SV). In case of a pressure build-up in the preheater or in case of a leakage in the steam line, sensors will trip the bypass system and the feed water is diverted by the inlet valve (UV) around the pre-heater and out through the outlet valve (SV). The main valves are medium actuated, i.e. they use the feed water pressure and flow to move the valves to the bypass position. There are pneumatic/manual periphery valves for triggering the system, bleeding the system during commissioning and post maintenance and for adjusting the stroke speed of the main valves. While in bypass mode the same pressure drop can be achieved as generated in the preheater. After commissioning is completed or after the valves trip, the valve position is set to normal manually using the integrated hand wheels and gags.