I work in safety management, and I’d like to share my understanding of water seals; there are many things I don’t understand, so I hope friends who happen to be reading this can offer some guidance! !
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This post was last edited by HaiChuanXiaoDangJia on 2018-8-1 at 18:26. I am in charge of safety management; while conducting inspections at the company’s anaerobic tank area, I noticed that water was continuously flowing out from the observation ports of the small outlet tubes of most of the water seals； But a few individual units are not flowing, and there is a smell of methane ； So I want to study the structure of water seals. Over time, these water seals provide insulation, and since the company is not in the hazardous chemicals sector but is involved in food processing, many of the equipment used is either homemade or assembled from used equipment. The photo shows the water-sealing tank that I’m interested in. The other image was drawn by me using CAD; my understanding and doubts are also explained in that image. It was created based on my own thoughts, so please help me check it – there must be some mistakes! Is it because the biogas enters below the liquid level in the water seal tank through the intake pipe, resulting in low pressure and the gas being trapped by the water? ； Once the biogas pressure on the side of the anaerobic tank rises, the biogas is forced into the water. It’s similar to when we hold a soda straw and blow air into a glass of water – biogas doesn’t dissolve in water, so it escapes in the form of small bubbles, breaking through the water seal and entering the space above it, from where it then enters the biogas storage tank through the outlet pipe. Is that correct?
I have conducted some research on water-sealed tanks, and I’d like to share some information for reference only:
It is normal for a small amount of water to leak from the water seal, and it is also normal for insoluble gases to escape. Also, your nickname seems a bit long, hehe.
This post was last edited by ylb913 on 2018-8-4 at 11:59. 1. The maximum water seal height is generally intended to prevent the equipment from experiencing overpressure; this is done to ensure the safety of the equipment. I am not very familiar with the pressure resistance capacity of these biogas-related devices. 2. In the case of intermittent water supply, in addition to the issue mentioned earlier regarding the decreasing level of the water seal due to frequent breaks, it also leads to an increasing concentration of dissolved substances in the water seal water; the stagnant water will naturally evaporate, resulting in an unpleasant odor. 3. Based on the description provided by the poster, it is necessary to supply water continuously, and the amount of water supplied can be adjusted. It is important to carry out adjustments proactively: find a level at which water does not flow out of the highest water seal outlet, reduce the level of the water seal, while simultaneously ensuring that there are no unusual odors in the area and that an appropriate amount of water is supplied.
You’re basically correct; a water seal utilizes a certain level of static water pressure to counteract changes in air pressure within the drainage pipe, thereby preventing gas from entering the container.
I’m curious about what purpose such a small water seal tank can serve. If the concern is backflow, such a small jar won’t be of any use at all.
Hehe, I watched an animated series in the past called \"Little Chef of China\", and that’s how I came up with this name.
Before posting this, I read your post from 2014; it was very professional, though it was difficult for me to understand. I wasn’t expecting you to come in person. I asked my department head, and he said that the water level in the water seal does not cover the biogas inlet pipe. When a certain amount of biogas accumulates in the three-phase separator at the top of the anaerobic tank and the pressure rises slightly, the biogas passes through the water in the water seal like bubbles, entering the space above the water surface in the water seal tank. If the pressure in the gas holder is high, the biogas accumulates above the liquid surface, and once enough pressure is reached, it enters the gas holder, causing it to expand. Usually, to maintain a certain pressure in the gas holder, we place some stones on top of it. At the overflow pipe, to prevent freezing in winter, water is added to the water seal 24 hours a day; as a result, water also continuously flows out from the overflow tube. This helps to maintain the water level at a level that covers the lower part of the biogas inlet pipe ； In summer, water is added intermittently. After adding water, by observing through the overflow pipe, it can be seen that there is water inside the overflow tube; however, this water can only come out to some extent when it overcomes the water seal. This confirms what you said – that the water level inside becomes lower and the concentration becomes higher. In summer, methane contains some water vapor, which enters the water seal tank together, causing the water level in that tank to rise as well; therefore, frequent drainage and water replacement are necessary. Gas may flow back up through the water pipe from above the water level in the water seal, but the water pressure in the pipe is over 4 kilograms, while the pressure of biogas is only a few tenths of a kilogram, so there’s no problem. This is what I know. Are there any questions? Also, in summer the water level in the water seal rises, and drainage is required frequently – is it because the concentration is too high, resulting in poor performance?
What’s wrong? Please discuss it: lol
May I ask what the water seal height for h3 should be to achieve the desired level? ? When there is no valve on the overflow pipe
May I ask, in this diagram: 1. After breaking through the water seal, why doesn’t biogas flow out in direction B via overflow? 2. The thin tube in the middle – the drawings indicate it as the intake pipe for air, but it seems to me to be an inlet pipe for liquid. The part on the left that is at the same level as the liquid surface is the sight glass opening