Questions regarding the water seal tank at the gas holder inlet
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The last edit to this post was made by Night ends, day breaks_QCBN on 2017-8-29 at 23:41. It refers to the water seal tank shown in the image; of course, there is no pipe like No. 3. I would like to ask: why does the water level decrease when the outlet of the water seal tank gets blocked? Why is the pressure inside the water seal tank much higher than the inlet pressure? And why does air still continue to enter when the pressure inside the tank is equal to the pressure at the inlet?
First, it is necessary to determine what gas is sealed in the water seal tank; the water seal pressure of this tank is determined by the depth to which tube No. 2 is submerged in the liquid surface
The drop in liquid level might be due to leakage from tube No. 3, but it’s hard to understand why the internal pressure is higher than the inlet pressure.
Gas enters, and the overflow port also has a U-shaped water seal; when the outlet is blocked, the level of the water seal drops and the internal pressure increases.
Your explanation of gas, water, and air is too simplified; there are several partitions inside. It is to increase the height of the liquid column.
The intake pipe should extend to the bottom of the tank. I’m not sure what the diameter of your pipeline is; if it’s large, then once the outlet gets blocked, water will fill the section of the pipe that extends underwater. The part of the pipe where gas flows should remain empty under normal conditions. Additionally, gas also occupies volume as it rises through the water. It loses air pressure; these two reasons can lead to a decrease in water volume. But I don’t understand why the pressure would be much higher than the intake pressure.
When the vent is not blocked, there is a certain height of gas space at the lower part of port No. 2. When it is blocked, as the pressure inside the tank increases, the water level in the tube rises, while the liquid level inside the tank drops (entering the intake pipe). The difference between the pressure inside the tank and the pressure inside the pipe is the static pressure of the liquid column.