What is the cause of the up and down movement of the bottom liquid level gauge in the distillation tower?
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In our unit, steam injection is used at the bottom of the distillation tower to separate naphtha, diesel, and residue. The level gauge at the bottom of the tower was originally a glass one, which made it possible to clearly see the material moving up and down. For safety reasons, it was later replaced with a magnetic float level gauge; however, the magnetic float became deformed and got stuck. Diagnosis in conjunction with the instrument also yielded no specific conclusions. Previously, in diesel hydrogenation units, I have also encountered fluctuations in the level gauge for the bottom liquid of the stripping tower (steam stripping). Personally, I think the abnormality in the level gauge is related to steam injection, but there is no theoretical support for this; an explanation is urgently needed
This phenomenon is not a problem with the instruments; it should be a problem with process control. Try reducing the load to see if the fluctuations decrease; if possible, establishing production conditions anew should help. The principle is caused by an imbalance between the rising steam and the flowing liquid.
Could it be that there are too many light components and an excessive amount of steam? Try reducing the reaction depth or the amount of steam to see
The reaction depth is not very great; the designed operating condition is a 99.8% conversion rate (for one full cycle), but now we have changed it to a single pass. I’ll try reducing the steam volume first. But could you explain why there is up-and-down movement inside the level gauge?
Reducing the processing volume requires the company’s approval. I’ll try reducing the steam volume first, but could you describe in more detail the direct cause of the interference, as well as the root cause?
What I mean is that the instrument readings are correct; what they indicate may be actual changes in parameters. The problem needs to be addressed and analyzed at its source. I’m not very familiar with the internal structure and principles of your fractionation tower; I have only analyzed it based on the principles of distillation towers. It is estimated that separation is also achieved based on the principles of mass and heat transfer between gas and liquid. There must be a certain ratio for this; it needs to be kept within a specific range according to the design parameters, as problems will arise if it goes outside that range. The apparent aspect of a problem is the parameters reflected by the instruments; when analyzing and addressing a problem, it is not sufficient to focus solely on issues with the instruments – it is more important to determine whether there are actual problems.
This has happened with our high-temperature models; in our case, it was caused by poor gas-liquid separation.
If it is not caused by an excessive gas load, then it is necessary to consider whether there could be issues such as blockages or flooding of the trays inside the tower. Looking forward to a follow-up response regarding the reduction in steam volume.
I don’t think the problem lies with the gauge either; I just don’t understand why abnormal gas and liquid conditions cause such large fluctuations in the level gauge’s float
It’s dropped a lot, but there’s no improvement; the liquid level still fluctuates up and down, and there are still clicking sounds inside