Can a valve be added to the liquid seal?
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The piping diagram is shown below. After emerging from the equipment’s outlet, the pipeline is first equipped with a liquid seal (with a design requirement of no less than 1 meter), followed by a sight glass and a valve, before entering the heat exchanger. The pipeline looks very unsightly like this; if a sight glass and valves can be added to the liquid seal, there will be no need to make a second bend. Personally, I think it’s not a big problem to attach a view mirror to the liquid seal; but would a valve work? If a valve is to be added, can it be installed anywhere, or must it be installed only when a 1-meter liquid seal is ensured? I earnestly request your guidance.
If a liquid seal is already in place, why is it still necessary to install a valve?
If valves and tests are truly necessary, the test can be carried out on the liquid-sealing vertical pipe, while the valve can be placed on the horizontal pipe, with flow going directly into the heat exchanger. A single U-shaped bend is sufficient as a liquid seal.
The main purpose of a liquid seal is to act as a safety valve; the valve is likely added to control the flow rate. In addition to serving industrial purposes, the placement of valves should also facilitate operation by maintenance personnel; if they are installed on horizontal pipes, their position is likely to be too high, making it difficult to open and close them!
It is more necessary for maintenance purposes, for reference.
If it’s placed on the horizontal pipe behind the U-turn, it will be over 2 meters long, and it’s indeed difficult to operate. This is the intermediate product from the acetic acid distillation tower; once distillation has reached a certain level, this valve needs to be closed, and only the product from the top of the tower should be extracted. So a valve was installed.
Okay, you’ve explained the general process flow; I now understand it! This valve is necessary; it should be related to the issue of shutting down the process, but where is this location? It should be designed with ease of operation in mind; the relevant processes should be easy to turn on and off!
In this case, it is better to place the mirror on the gas-liquid interface side, and the valve at a conveniently accessible position on the liquid phase side. First, it serves as a barrier for process operations; second, it prevents fluctuations in pressure differences caused by changes in operating conditions, allowing for effective adjustment of the liquid seal height to ensure proper liquid discharge.
A sight glass is installed on the first vertical pipe through which the liquid flows, while a valve is installed at the same position on the second vertical pipe of the U-shaped design. Installing valves on the liquid seal is common, especially in vacuum distillation systems.
A sight glass is installed on the first vertical pipe through which the liquid exits, while a valve is installed at the same position on the second vertical pipe of the U-shaped design. Installing valves on the liquid seal is common, especially in vacuum distillation systems.
Thank you all for your patient answers! Finally, I placed the mirror on one side of the U-turn and the valve on the other side (the answer from floor 9), which makes it look much better. Wish you all a happy New Year!