The start-up check valve is stuck, and the fluidization in the start-up line is abnormal
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This post was last edited by Final Fantasy on 2010-4-25 at 20:07. Recently, our unit’s catalyst regeneration system has been experiencing various problems: the regenerator plug valve gets stuck, its opening degree fluctuates significantly, and the fluidization in the regenerator circuit is not proper either; even when the regenerator plug valve is fully closed, it is still not possible to effectively control the amount of material stored in the stripping section. The company has also taken some measures, including organizing workshops for instrument maintenance and repairs, to clean the hydraulic oil filters and inspect the actuators of the raw material check valves. But the fundamental problem remains unsolved; if it can’t be resolved again, production will likely have to stop. Could a fellow Haiyou help analyze this? Thanks in advance!
Since other relevant parameters are not visible, it is impossible to determine the exact cause. It is recommended to pay attention to the following aspects: 1. The normal automatic position for feeding slurry. Significant fluctuations in the valve position at this location are mainly caused by changes in the difference between PV and SP. It is necessary to closely monitor the sequence of changes in the level of material in the settler and the valve position, as well as changes in the density of the raw slurry and the raw slurry sleeve, to determine whether the issue is indeed related to the instruments 2. Check whether the expansion amount of the future riser is at the normal level? If it is too small or there is no valve head to be plugged, the likelihood of problems with the valve stem and the lower end of the vertical pipe is high ； 3. If it is indeed a problem with the instruments, things are simpler: check the original opening degree, the differential pressure between the two vessels, and the level of material in the settler. Set the opening degree at a specific value and maintain the differential pressure between the two vessels within a certain range. Usually, the level of material in the settler changes accordingly (the changes should not be too large, as sharp fluctuations can affect the stripping effect) ； 4. Instrumentation issues have been ruled out; it is necessary to check the on-site data to determine whether there might be perforations in the settler or in the raw material lift pipe. This requires taking into account various parameters such as the settler level, the density of the raw material lift pipe, the density of the sleeve, the differential pressure, and the temperature of the regenerated slurry during periods of abnormal changes. Different perforation locations present different symptoms, so a detailed analysis is needed. (Once a perforation occurs and small fragments fall off, fortunately, getting stuck at the site of the perforation will also disrupt the existing balance; once those fragments are worn away, things change again.) The zero level in the settler (faulty plug valve), an inability to maintain a stable level due to perforations in the settler (perforations in the stripping section, followed by perforations in the raw material riser tubes – in the dilute phase and within the sleeves). That’s roughly my suggestion; actual verification will still require data. The specific on-site situations are due to different reasons.
1 There may be a detached lining or burnt debris in the valve head area. 2 Check whether the valve head of the plug valve is worn out. 3 Verify whether the regenerator riser and the valve head of the plug valve are aligned properly. 4 Check whether there are any perforations in the stripping section of the settler, including the regenerator riser. These issues can be addressed one by one based on the operational conditions.
Compare the position at which the plug valve gets stuck after being closed with its previous position; if it is the same as before, there may be a problem with the valve head; if it is different, there could be an issue with the stripping section or a perforation in the vertical pipe.
Everyone is rushing to finish speaking; the super editions have already arrived – what more can we say? But I think it is also possible to determine whether the pipelines in the line have been worn through by using external loose air or loose steam. If one or two of them are truly worn out, it should not affect the fluidization effect; our device currently has 2 loose points that have been worn out. The incoming line is fine, so we should think more about the instrument; it’s probably the instrument that has a problem. If there are any mistakes or inaccuracies in what I say, please feel free to point them out
Continue production to achieve greater benefits. Change the stop valve to manual operation, fix one valve position, and use lift air, differential pressure controllers, etc. to control the material level; I’m sure you’ll be able to operate it well.
Possible causes: First, metal particles may have fallen and settled at the plug valve, causing blockage and vibration. Second, abnormal fluidization within the device itself may lead to the plug valve being opened or closed frequently in order to maintain the correct material level, resulting in fluctuations in the readings.
Personal opinion: 1. The plug valve is stuck (increase the level in the settler and try moving the valve position)； 2. There is a perforation ； 3. The plug valve is worn out or the valve stem is not in the correct position ； 4. Instrument issues (this is possible). . It’s frustrating.) ；