The turbine vacuum is poor
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The turbine vacuum of the centrifugal compressor is dropping. The gas seal, extractor, shaft seal, and surface cooling liquid level are all fine; the condensate pump is operating properly, there are no blockages in the pipelines, and both the steam system and the water system as well as the process equipment system are functioning normally. What other factors could affect the vacuum?
It depends on how quickly the vacuum level drops. If it decreases slowly, it’s very likely that there is a leak in the vacuum system. If it drops suddenly, it is possible that during the change in rotation speed, the efficiency of the turbine deviates too much from the efficiency curve; as a result, insufficient work is done by the steam, the exhaust temperature at the last stage of the turbine rises, and this in turn leads to a decrease in vacuum level.
It depends on the type of compressor turbine you have – whether it’s a fully condensed type or an exhaust-condensed type. Generally, the issue that most likely causes a drop in vacuum level is the extractor; fluctuations in its steam supply can affect the vacuum level. Additionally, check whether there are any minor leaks in the reheat apparatus, and whether the vent valve of the reheater has internal leaks or isn’t closed properly. Also, consider whether the water seal of the reheater pump is in use, as well as whether the water seal of the atmospheric safety valve is functioning correctly, and whether the sealing steam is being used
3# sd00000: What do you mean by a rehydration unit? Could you give me a detailed explanation of it? I really haven’t come across this term before
4# lxdcyang The rehydrator is the surface condensate gas you mentioned! Furthermore, according to the original poster everything is normal – how do you know that? It’s necessary to check each item one by one. Some issues can be detected while the machine is running, such as leaks in pipes, flanges, and valve gaskets; others must be checked when the machine is shut down, such as leaks in the shaft seal system, inside the vacuum pump, or within the surface coolers – all of which can lead to a decrease in vacuum level! Therefore, it is necessary to make a preliminary selection based on the observed phenomena and conduct systematic investigations to identify the problem; one cannot simply claim that everything is normal – otherwise how can others help analyze the situation?
5# wjh5418: Since the vacuum level drops simultaneously in both compressors, it is possible to rule out faults in the equipment itself; inspections of the steam and water systems revealed no issues.
I guess the vacuum level here is dropping slowly; our unit’s vacuum level was also dropping slowly some time ago. It was only after excluding the remote transmitter that it was discovered that this transmitter was showing incorrect readings due to a lack of condensate; upon contact with the technicians, the transmitter was replaced and then there were no more problems.
There are actually many more aspects that can be analyzed regarding the drop in vacuum pressure. Everything mentioned by the original poster seems fine, but it’s not possible to be 100% certain; it is recommended to conduct a more thorough review； Leaks anywhere within the vacuum system can cause a drop in vacuum pressure ； If local vortices are generated within a vacuum system, there are many possible causes for this, and it can lead to a decrease in vacuum pressure! I once encountered a situation where it seemed that in a certain type of vacuum transmitter, as long as there was liquid accumulation inside, the vacuum level would gradually decrease, and the problem persisted even after some time had passed. . . . I’m not really sure what it looks like exactly! It’s not easy to find Chalu these days; small places are hard to locate. It’s recommended to apply butter to areas like flanges to seal them!