What is causing the tower pressure to drop slowly?
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This post was last edited by you*n*nyou on 2011-8-24 22:12. Recently, our system underwent a thorough cleaning and purging process; it should now be able to operate for about half a month. All of our operational parameters are normal, and the purity level is satisfactory. However, the tower pressure is slowly decreasing. What could be the reason for this? By the way, I would like to ask whether it is feasible to reduce the valve opening of the liquid nitrogen throttle when the tower resistance decreases ?
Reply to 1# Gao Jing6522: The tower pressure is decreasing, while all other parameters remain stable. This seems unlikely; the tower pressure has a significant impact on other parameters such as purity and temperature. It is recommended that the user check whether there are any issues with the pressure transmitter or the pressure lead pipes.
As mentioned above, all indicators are normal; check whether it is due to the gauge, or if the pressure lead pipes are blocked or leaking. The pressure at the molecular sieve outlet remains unchanged, while the pressure in the lower column decreases; this results in an increased pressure difference across the heat exchanger, indicating that the heat exchanger is blocked. Check the water content at the molecular sieve outlet. Since you have just done the cleaning, it’s impossible for dust or something similar to cause an increase in pressure difference.
We measure the moisture content at three points, one of which is after purification. The moisture content measured one after the steam heater and the other after the compressor cooler was around -76. No pressure difference could be detected after the heat exchanger; the purity of oxygen, nitrogen, liquid air, and liquid oxygen was all within acceptable limits. The current issues are high resistance in the downflow tower and low tower pressure. The amount of air entering the tower was around 33,500 at the beginning; it can now maintain this level for about half a month. Moreover, since the ambient temperature isn’t high, the air flow rate is only 31,800. I’m not sure what the cause of this is
Reply to 4# Gao Jing6522: What about the pressure after the molecular sieve? Is there no visible change in the purity trend? Then it’s still a doubt about the measurement issue – are the gauge for tower pressure and the one for resistance connected together? When the linkage between these two gauges is removed (if there is any), try using a sampling tube; after all, on such a large tower, a tube that is so thin is prone to various problems
Then I have a question: if the tower resistance decreases, is it possible to reduce the liquid nitrogen throttle valve? If it is turned up, will the resistance keep decreasing? ?
Based on what the poster has described, with the tower pressure decreasing while all other parameters remain stable, the continuous fluctuations in tower pressure indicate that there is a problem with the measurement point for tower pressure. Check whether the pressure tapping tube is leaking or blocked. Then check the transmitter to see if it is damaged, and replace it if necessary.