Is the pneumatic single-seat control valve used for nitrogen sealing of the storage tank open when pressure is lost or closed when pressure is lost?
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The storage tank originally used a self-acting nitrogen seal valve, but it proved to be ineffective in practice; later, a pressure transmitter along with a pneumatic control valve was installed. When designing the control valve, was the opening degree of the air-loss valve set appropriately? The storage tank is equipped with a breather valve and a safety valve, with a nitrogen pressure of around 0.7 MPa
The last edit to this post was made by Coffee Pig on 2021-3-26 at 20:26. It depends on the specific circumstances – it’s necessary to consider how great the risk of air entering the tank is Generally, it is more often designed according to FC standards ； If designed according to FO, it is recommended to install a flow-limiting orifice plate on the nitrogen pipeline!
It’s usually FC; using FO carries too much risk. With FC, if a fault occurs it will shut down, and a low tank pressure alarm is issued to alert the operator to conduct a check.
This post was last edited by HEJIYUER on 2021-3-30 at 23:09. For pressure relief/decompression, FC is used in both cases.
The nitrogen side pressure is higher than the tank’s design pressure; it is recommended to shut off the gas supply.