Has anyone seen this type of liquid-sealed tank? What is the principle?
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As shown in the figure above, a flammable and explosive liquid storage tank is equipped with a nitrogen seal as well as a liquid seal tank; the liquid in the liquid seal tank is immiscible with the liquid in the storage tank. I have a question: has anyone seen a similar design? What is the purpose of these two liquid seal tanks? How does the principle work? Just by looking at the diagram, if the liquid seal tank serves as a vent valve, then gas needs to be discharged when material is fed into the storage tank. The gas released passes through pipe A, bubbles up from the liquid seal tank on the right side, and then is discharged through pipe C. Is this understanding correct? Air needs to be drawn in when discharging from the storage tank, and nitrogen is supplied through a self-acting pressure control valve; then won’t the liquid seal tank cease to function? And it seems like Pipe B isn’t very useful. . .
With this setup, a fire on one end will not affect the other end
The liquid contained in the liquid-sealed tank can be used to process materials. The materials should not be released directly into the atmosphere nor allowed to enter the air. We have something similar installed. The two tanks can be considered to be in series, with the space in between serving as a buffer and a vent valve.
Pipe B is probably meant to prevent backflow of the sealing liquid due to too low nitrogen pressure
On the one hand, when there is insufficient nitrogen supplementation, it can be added through tube B to prevent the tank from deflating. On the other hand, in case tube A becomes blocked, exhalation can be sealed by liquid from point B. If both liquid seal tanks are equipped with level monitoring, it is also possible to determine which pipe is blocked or whether the liquid seals are functioning properly
It is said that water-sealed tanks are not used for Class A liquids. It is difficult to avoid air backflow in case of an abnormality with any type of water-sealed tank. If the tank pressure and the liquid level in the water-sealed tank are properly managed on a regular basis, this will not happen
It’s easy to understand during exhalation: gas enters through pipe A and is discharged underwater, with the liquid seal preventing air from entering. During inhalation, gas enters through pipe B and also goes underwater into the tank; although air does enter, the liquid seal ensures that it isn’t in constant contact with outside air, so the amount of air that enters is limited, reducing the risk of combustion and explosion
The function of pipes A and B is to prevent air from entering the system when there is no pressure in nitrogen and when material is being discharged from the storage tank, as the bottoms of the two small tanks are connected to each other