Determination of nitrogen seal pressure
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This post was last edited by chinazwr on 2009-5-12 20:04. In storage tanks, nitrogen blanketing is often used to ensure safety; but how is the pressure of nitrogen determined? What is the conversion relationship between atmospheric pressure and the saturated vapor pressure of the liquid stored in the tank? ? ?
What do you mean? Can’t quite understand it?
There is no dedicated nitrogen pressure; typically, a pressure-controlled valve is installed on the nitrogen line to supply nitrogen into the tank once the pressure inside it drops. The pressure set by the pressure-controlled valve is the operating pressure of the tank, and it has nothing to do with the pressure of nitrogen itself. Good luck. . .
For atmospheric-pressure tanks equipped with breather valves, to prevent air from entering, the gas seal pressure value is generally set at 0.0005~0.001 MPa(g); this is an empirical value.
The nitrogen seal pressure can be 0.1–0.2 MPa, but it should be determined based on actual conditions
The answer from the friend on the 4th floor is quite appropriate. Atmospheric pressure tanks have a specific design pressure range, and the set pressure of the vent valve must fall within this range.
Regarding the steam at the top of the tank, nitrogen can only serve to seal it; the liquid material will still evaporate, and this has nothing to do with whether the nitrogen pressure is higher than or equal to the saturated vapor pressure! I agree that the nitrogen seal at the top of the atmospheric pressure tank should not be too large
I don’t know. But our nitrogen pressure is generally kept at 1–2 KPA
The design pressure for ordinary dome-shaped storage tanks is typically between +1960 Pa and -490 Pa. The set pressure of the vent valve should not be higher than the design pressure of the tank, while the pressure of the nitrogen seal should be lower than the set pressure of the vent valve. Personally, I usually set the pressure for the breathing valve between -295 Pa and +1750 Pa, and the nitrogen seal pressure between +1000 Pa and +1500 Pa.
Most commonly, atmospheric pressure tanks require nitrogen sealing, but this is only applicable to materials with high volatility; otherwise, they can be directly exposed to the atmosphere. The nitrogen seal has two main functions: 1. Isolated from the external environment to reduce volatilization losses. 2. It is used to maintain a certain operating pressure, especially when nitrogen needs to be added while pouring materials out of the tank. During canning, it is necessary to expel the displaced gas outward. So it is usually also connected to the emission system. But nitrogen sealing is not only available in atmospheric pressure tanks. For example, for volatile materials with a relatively high vapor pressure, nitrogen blanketing is also required. For the storage of mixed carbon 5 as I have seen it, the operating pressure is maintained at 1 kilogram, with the nitrogen seal set at the same value. Therefore, the pressure of the nitrogen seal should not be lower than the vapor pressure; otherwise, the purpose of the nitrogen seal is lost.
Thank you all! ! :handshake :handshake
If the nitrogen sealing pressure is set at 1–2 kilograms, then this storage tank becomes a pressure vessel; the material used for the equipment as well as the wall thickness must be increased significantly, which makes the cost too high. It is better to maintain a low pressure and treat it as a normal-pressure vessel.