Issues regarding the pressure of natural gas condensate storage tanks
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I need help. V3701 in the diagram is used for storing natural gas liquefied gas, and I have two questions for the experts: 1) Fuel gas is used to control the operating pressure of the storage tank, which is set at 0.02 MPag. Why is a storage pressure of 0.02 MPag required? 2) Can it be discharged directly during loading, without the balance line being connected to the gas phase of the condensate tank?
Nitrogen sealing should be a safety consideration; a pressure of 0.2 is likely related to the vaporization temperature of this medium at that temperature
Well, in this case, the pressure isn’t too high
1. The condensate tank should be maintained at a slight positive pressure (2 m of water column) to prevent air from entering the tank and creating an explosive gas space. 2. The loading balance line should discharge the gas inside the vehicle into the tank based on the principle of volume exchange, and then allow for centralized venting through stepwise regulation; this helps to reduce the number of venting points and meet environmental and safety requirements.
I’ve seen that some design institutes equip their condensate tanks with a vent valve that is directly connected to the vent pipe, without any such micro-positive pressure mechanism. Isn’t it risky to have it directly connected to the atmosphere?