Problems with the air-cooled condenser return pipe
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This post was last edited by you*n*nyou on 2012-2-24 at 19:14. The device in question is a 25,000 model air separation unit of the Chuan Kong brand, with air-cooled towers that have return pipes; the indicator light shows red sometimes and green other times. The manufacturer’s technicians said that if it shows red, there might be water reaching the molecular sieve. In the past two months, it has shown red quite frequently, but the molecular sieves are functioning normally. I wonder if anyone who has operated this device can provide some insights
Check whether the gauge is working properly; if it isn’t, it will display red.
It seems that I have never encountered the situation described by the original poster. Also, we don’t have such a process here. There is no such setting on the DCS control interface either. Guess: There is a feedback lag between the liquid level in the air-cooling tower and the drainage valve of that tower. When the liquid level reaches the upper limit alarm, if the water supply control valve for the air-cooling tower does not respond promptly, this will cause the emergency drainage valve to open for drainage; once the liquid level drops, a interlock mechanism will then close the drainage valve. In this way, water will flow out through a high-water-level drainage pipe. Is there water in this section of the pipe?
This level alarm is not very useful; it is recommended to disable it.
I remember that a flow switch is installed in this return pipe; when the return water from the air cooling system flows abnormally and the volume of water passing through the return pipe increases, this switch is activated. I encountered this in a project I worked on before, but I’ve never actually implemented it. Which expert could give some advice?
The water return pipeline for the air-cooled tower runs from below the mist catcher at the top of the tower to the bottom of the tower. A large pipe is installed, with a smaller-diameter pipe attached to it; the level switch is located on this smaller pipe. Under normal operating conditions, there is little water at the top of the air-cooled tower, so water can flow from the smaller pipe to the bottom of the tower. When the liquid level is low or the level switch shows a green indication, this is normal. However, in the event of a water overflow issue, the amount of water at the top of the tower increases, and the smaller pipe is not able to handle such a large volume of water, which results in an alarm indicating a high liquid level, or the level switch shows a red indication.
Agree with what was said above: 28,000 low-pressure air separation unit, equipment from Sichuan Air Separation. Our air-cooled condenser return line is designed as a large pipe, which narrows to a smaller-diameter pipe in the middle; a flow control orifice plate is installed on this smaller-diameter pipe, and the level switch is placed above the orifice plate. When stacking the fillers in the air-cooling tower, we went inside to take a close look; the large pipelines are installed above the rising air tray and below the wire mesh mist catcher. During normal operation, the airflow in the lift pipe contains little mist, so the mesh mist remover removes a small amount of water; as a result, less water flows down along the return pipeline. The flow-control orifice plate located in the middle of the small tube is sufficient to ensure the proper return of water volume. If water is present in the air-cooling tower, an excessive amount of water flows back, causing the level gauge to indicate a higher liquid level than actual.
Such a setup is an excellent precaution against water accumulation in the air-cooled tower.