The air volume is insufficient; the pressure at the bottom of the tower is 0.38 MPa, and the resistance is around 13.5. What does the periodic fluctuation in oxygen purity indicate?
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The air volume is insufficient; the pressure at the bottom of the tower is 0.38 MPa, and the resistance is around 13.5. What does the periodic fluctuation in oxygen purity indicate?
What is the normal resistance at the lower tower, and what is the situation under the conditions of the upper tower? There isn’t enough data provided to make a judgment.
Try reducing the purity of the liquid air to lower levels in order to decrease the amount of oxygen extracted from the product.
Our system is now in poor condition: the exhaust pressure of the air compressor is 0.525 MPa, and the amount of air processed is around 22,500 units per day; this value keeps decreasing day by day. The pressure at the lower tower is 0.38 MPa, and the resistance is currently only 13 MPa. Daily tests conducted in the laboratory show that the purity of the liquid oxygen is very high, exceeding 40%. Both liquid oxygen and oxygen do not meet the required standards, and the three temperature differences at the exit of the heat exchanger are also between 7 and 10 degrees Celsius. Is the heat exchanger blocked?
What is the liquid level in the lower tower? It is recommended to check whether the position of the local valve matches that shown on the DCS. We have encountered situations where a certain valve connecting the lower tower to the upper tower was left fully open locally, which leads to this issue; the temperature difference on the hot side of the main heat exchanger becomes large. Try adjusting the valve to see if that helps
It’s not easy to operate in a low-temperature environment for air separation units; if the amount of air processed decreases, all operating parameters need to be adjusted accordingly. I suggest reducing the valve controlling liquid nitrogen flow
We’ve already reduced the setting of the liquid nitrogen throttle valve by over ten degrees, but it doesn’t have much effect. Moreover, the valve that controls flow through the heat exchanger can’t be adjusted either; we damaged one of them when trying to adjust it – it was leaking and sticking. Now, during cold blowing, the amount of regenerated gas is around 7800, the oxygen level is around 5200, and the nitrogen level is around 9000. We don’t dare make any further adjustments
It seems that there might not be enough liquid air flowing down to the lower tower; the oxygen-enriched liquid air stream entering the upper tower contains gas. There could be an issue with the liquid level in the lower tower, or it’s worth checking what the actual opening degree of valve V1 is and how it compares to normal values
Reply to 7# Gao Jing6522: Calculate the imbalance between intake and exhaust air. Sidestream ventilation, ‘dirty nitrogen regeneration gas’, dirty nitrogen denitration cooling tower, pure nitrogen gas – and that’s not including anything else; there are more elements as well. I think the problem lies in the distillation section.
The purification efficiency of the molecular sieve adsorber is no longer satisfactory; shut down the system to activate the molecular sieve, and once it has been activated, heat the equipment thoroughly.
The molecular sieve was replaced just three or four months ago; it was activated after the replacement, and all valves are functioning properly. I calculated that the amount of gas exiting is greater than the amount of air entering, but I’m not sure as to why. Oh, the valve that sends nitrogen to the water-cooling tower won’t move – when that valve is opened, more air can enter the system. However, with an expansion volume of around 5500, the liquid level doesn’t rise; instead, it drops. The temperature difference across the heat exchanger is higher, but once the valve for sending nitrogen away is closed, the amount of air decreases, and the liquid level in the main cooler rises to 4500, with the same temperature difference across the heat exchanger. I really can’t figure this out right now; I hope the experts here can offer some suggestions