R
The client site I am at is using MOVs with a very low velocity limit, 0.42%/sec. The client has specified these actuators and has been told by N/E that the sky vents are for drum temperature rate of change control only and used only during start up of the unit.
This is the first time I have encountered MOVs in this application and the first time I have seen such a low velocity limit on a critical valve.
My previous experience with N/E boilers has been that the sky vent is very fast acting and is used in conjunction with the bypass valves to help control pressure transients.
In addition normally, at least from my experience, the sky vents are used for pressure control to prevent the PRVs from lifting when the condenser is unavailable or the bypass valve trips due to over temperature.
I would like to hear from anyone who has MOVs on their sky vents and their experience with control of the pressure.
Thanks,
Ron
This is the first time I have encountered MOVs in this application and the first time I have seen such a low velocity limit on a critical valve.
My previous experience with N/E boilers has been that the sky vent is very fast acting and is used in conjunction with the bypass valves to help control pressure transients.
In addition normally, at least from my experience, the sky vents are used for pressure control to prevent the PRVs from lifting when the condenser is unavailable or the bypass valve trips due to over temperature.
I would like to hear from anyone who has MOVs on their sky vents and their experience with control of the pressure.
Thanks,
Ron
