Liquid seal tank design
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As shown in the diagram: The oil-containing gas is drawn in by the fan and enters containers ①, ②, and ③ sequentially for gas-liquid separation. The liquid is collected in container ④, where a certain level of water forms a water seal to prevent gas from circulating within containers ①, ②, ③, and ④ when the fan is operating. The gas is drawn out through the pipes at the top of the containers, while the liquid flows into container ④. In this way, the water seal operates under negative pressure. During operation, the water level in the connection pipes between containers ①, ②, ③, and ④ should rise to a certain height, with the water level in the pipes connecting ③ and ④ being higher than that in the pipes connecting ② and ④, and further higher than that in the pipe connecting ① and ③. The lengths of these three pipes can be calculated based on the pressure generated by the fan, in order to prevent the sealing liquid from being drawn out by the fan. The liquid seal tested recently in the \"Petrochemical Design Manual\" is only suitable for conditions of normal pressure and slight positive pressure. Is there any issue with using it under negative pressure as shown in the diagram? I earnestly ask fellow professionals to share their insights on this.
Refer to the design of the torch gas water seal tank.
Okay, thank you. May I ask which book this content is from? Is there an explanation for it? It’s a bit hard to understand
Under normal operating conditions (stable emissions), the flare exhaust enters the water seal tank through the main pipe; under the water seal condition, the gas overflows to the flare for combustion while the liquid remains. When the liquid level rises above a certain threshold, the excess liquid is discharged from the tank. Under abnormal operating conditions (such as sudden high emissions, e.g., an accidental shutdown of the plant), a large amount of flue gas from the main pipeline flows into the water seal tank, causing the balance function of the water seal to be lost. The gas, carrying liquid with it, is then rapidly sent to the flare for combustion, thereby ensuring the intrinsical safety of the plant.
It’s easy to find time! The height from the liquid surface to the material inlet must be calculated accurately!
What does the immersion weir at the water seal end where the torch main pipe is connected look like? The diagram is rather abstract and I couldn’t understand it
The last edit to this post was made by The wise are enlightened on 2021-4-1 at 18:45. It involves creating a ring of discharge holes around the outlet of the pipe; however, the diameter of these holes (i.e., the height of the weir) needs to be calculated carefully so that the discharge pressure is sufficient to allow the gas to be released gradually, while also ensuring a water seal effect – without preventing discharge under abnormal operating conditions.
Is that so? Sorry, I still don’t understand. Could you please draw a sketch when you have time?:
Water supply and drainage can be replaced with electric valves or automatic control.
A negative pressure liquid seal is completely suitable, but when used in front of a fan, it is necessary to take into account the impact of liquid on the fan’s operation in order to prevent damage to the equipment.