Analysis of the reasons for sudden shutdown due to excessive vibration in the turbine of a nitrogen pressure unit?
Thread Content
Our plant is equipped with a Shengyu 32,000 Nm3/h nitrogen pressure generation unit. During the night shift today, the unit shut down suddenly due to excessive vibration in the X-direction of the turbine’s front shaft. From a process operation perspective, there were no changes in parameters such as temperature and pressure before the shutdown; the curves on the ITCC display showed a sudden spike in vibration levels (rising from normal levels to 100 um). I think it’s likely a problem with the instruments Could it be that a loose connection caused changes in the resistance value, which in turn generated a signal that led to the system shutting down, before it recovered again? The way to avoid this is to delay the interlock that causes the vehicle to stop for a few seconds. I think with such a long coasting time for the vehicle, a few-second delay shouldn’t be a problem, but it didn’t work? ? Have any of the seniors encountered this same issue? I’d appreciate some advice (It didn’t appear even after it was turned on again.)
Why does the original poster want to make changes? Are you trying to leave some time to release the interlock? In just a few seconds, you can’t determine whether it’s a mechanical failure or a gauge issue. If it’s caused by a equipment failure and you turn off the interlock at that time, the consequences are obvious. From any perspective, this delay must absolutely not be done.
We’re here to support you; not only nitrogen compressors, but also air compressors and pressure boosters all come equipped with vibration-based delay mechanisms to prevent shutdowns caused by sudden fluctuations in signal values.
I’ve been working with instruments for several years, and in my opinion, there is interference at play. Let’s rule out a few possibilities first: firstly, could anyone be using wireless devices such as mobile phones or walkie-talkies near the compressor vibration sensors? This is likely the cause; it has happened several times in our facility, and it’s an occasional issue. Second, check whether large electrical equipment was turned on before and after getting out of the vehicle, especially devices such as frequency converters, as these can all cause interference. Third, check the instrument grounding to ensure it is reliable and proper, and measure the grounding resistance to verify that it is within the specified range. It is also important to pay special attention to whether there are devices with strong current fluctuations near the instrument grounding point, such as welding machines, as these can cause interference. Furthermore, regarding the issue of adding a delay to the vibration alarm, it is highly recommended not to make arbitrary changes. The vibration probe serves as a means for very rapid response as well as a sensor that monitors the actual conditions of the compressor; if a delay is applied carelessly, it may result in delayed shutdowns and delayed protection, which can easily lead to serious consequences. After all, the most serious consequence of instrument malfunction is shutdown, while protection delays can lead to severe damage to the equipment.
Was it determined that it was a gauge fault? Is it a short circuit, causing the measurement value to be infinite? If false alarms occur at that point constantly (for unknown reasons), it is possible to increase the interlock delay, provided that your other vibration measurement points are stable and reliable~~
The instrument failed to identify the cause； Other vibration points are normal ； From the perspective of ensuring the safe operation of the equipment, the suggestion to implement delays should not be adopted ； But from a process operation perspective, shutting down the plant once is a very troublesome affair; not only does it result in high costs, but it also increases various risks during operation ； So personally, I think it’s still appropriate to delay it a bit ； The main thing is for everyone to reach a consensus; one person cannot make the decision alone, and holding a special meeting can also resolve the issue. After all, losing millions per day just from stopping operations for a day is no small amount.
Vibration-delayed derailment – it must be included, but the delay cannot be added on top of the existing one.
Instrument problems can be mitigated through system shielding. Many instruments exhibit signals that rise or fall suddenly; such signals go straight to their maximum or minimum values, which is different from the signals generated by ordinary mechanical failures. These can be identified using the control system
Signal interference must be eliminated~~
Generally, the shielding of signals from such instruments is very good; if interference manages to get through, it’s necessary to thoroughly check the shielding system. We had issues with interference in the speed measurement signal from one of our expanders. The source of this interference was indeed the frequency converter located nearby. Since the frequency converter was necessary for operation, we had to look for the problem in terms of shielding. Eventually, it was found that the signal cables used to transmit data from the field to the DCS were not appropriately selected; after replacing those cables, the problem was resolved.
Now, when making arrangements, interference issues are generally taken into account, and corresponding measures are in place~