Seeking advice on the setting for air separation V11 (liquid nitrogen reflux from the lower column top)
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Dear teachers and seniors, I have always had a question I would like to ask. Our unit here uses a full-low-pressure air separation system; normally, regulation is accomplished solely by using V2 (liquid nitrogen throttling) to control the liquid air in the lower column, while valve V11 is not used in daily operations. Is it true that the reflux ratio can be adjusted merely by changing the opening degree of V2? As stated in the \"Oxygen Producer FAQs,\" the typical setting for V11 is 2–3 turns. Is this value a problem throughout the operation until normal conditions are reached? Is it still necessary to make adjustments based on operating conditions? Thank you all, it needs to be resolved urgently!
It hardly adjusts, unless the operating conditions are changed significantly!
Some units are not equipped with a liquid nitrogen reflux valve for the downcomer, and in most cases they remain fully open during normal operation. Action is only required during the fluid accumulation or heating phase; for normal adjustment, use V2
Then when should it be turned on while driving?
V11 mainly affects the air intake volume to the tower. If, during startup, you have already set V11 to its appropriate position (meaning that the air volume entering the tower is at the desired level), this valve remains almost unchanged during operation. Generally, we use liquid-air valves to adjust the liquid level in the lower tower, and liquid-nitrogen valves to adjust the reflux ratio in the upper tower (under normal operating conditions, these adjustments are made in small increments). The V11 valve is only activated in the event of a significant load change.
When there is liquid accumulation, V11 can be closed to temporarily stop the main cooler from operating; once the liquid level is sufficient and purification begins, this valve can be gradually opened~~
For normal load fluctuations, it is not necessary to adjust V11; however, in the case of significant load changes, its opening degree needs to be adjusted. During normal operation, only the liquid nitrogen valve that controls the flow from the lower tower to the upper tower needs to be adjusted. Additionally, valves with unreasonable design requirements need to be considered separately~~
On our end, we usually run it for two or three rounds; the operating conditions are adjusted via V2. Unless there’s a problem with V2 and it can’t be fixed right away, we can temporarily adjust them using V11