Problems with liquid nitrogen throttling valves
Thread Content
When the valve of the liquid nitrogen de-gasification tower is opened wider, does it result in less reflux liquid flowing downward, or toward the upper tower? At present, the purity of the gas in the night sky is only at level 30; by slightly increasing the throttle valve for liquid nitrogen going to the upper tower, the purity of the nitrogen gas emerging from that tower deteriorates immediately
What about the purity of liquid nitrogen at the bottom of the tower? Generally, the liquid nitrogen deargonization column is located before V3, so it has a significant impact on the reflux ratio of the lower column~~ Adjust the upper and lower columns first, then work on the argon system~~
A 30% level for liquid air indicates that the purity of liquid nitrogen is very high. Could it be that the reflux ratio at the top of the tower is too low?
30% is a bit low; the normal range is 35–36%~~
There is no purity analysis for the liquid nitrogen in the lower column. The problem is that once the throttle valve for the liquid nitrogen in the upper column is opened slightly, the purity of the nitrogen exiting the upper column can reach several hundred PPM. It is suspected that there is less liquid nitrogen in the lower column as well
Yeah, that shows the purity of the liquid nitrogen in the upper tower is fine. Moreover, adjusting the liquid nitrogen throttle valve just a little bit will definitely not cause the nitrogen level in the upper tower to reach several hundred PPM. I’m not sure what the reflux ratio at the top of the upper tower is
How do you analyze the purity of your liquid air? Could there be an issue with the analysis? Generally, a change in liquid air level of 35-40% has little impact on nitrogen purity. Is your V11 valve open?
The liquid nitrogen in the lower column is not pure; by closing the throttle valve at the upper column, the purity of the nitrogen coming out of the upper column improves immediately. This means that there will be less reflux liquid in the lower column, and as a result the purity of the liquid oxygen should be higher. The manual analysis showed a value of 34, with the oxygen purity being around 99.45 only
V11 fully open, manual analysis by liquid air,
I think it’s still necessary to analyze the purity of liquid nitrogen; nitrogen analysis probes can be used, with the analysis tube connected on-site to the liquid nitrogen analysis pipeline in the lower tower for testing. Just check what the nitrogen purity is at your current setting; it’s likely caused by poor quality of liquid nitrogen. The purity of Liquid Air can only be used as a reference and cannot serve as the sole basis for adjustment.