Seeking help with the operation of a negative pressure plate distillation tower
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We are about to change the distillation unit for coal tar processing from an atmospheric pressure tower to a vacuum tower. After this modification, the existing operating parameters will no longer be useful, and everything will need to be determined anew. I’m very curious to know what the difficulties and key points are in operating a vacuum tower compared to a normal-pressure tower How to detect leaks in negative pressure devices? If a vacuum pump is used in the negative pressure system, what could be the cause of the periodic vibrations? Thank you
1. After vacuum operation, the relative volatility of various components changes; therefore, the height of the tower required to achieve the same separation goal must be adjusted, and this requires calculations by design engineers. 2. The key aspects of vacuum operation are not very different from those of normal-pressure operation; the important factors include the top temperature, bottom temperature, feed temperature, reflux ratio, product withdrawal rates from the tower and the reactor, as well as the degree of vacuum. 3. Methods for testing for leaks in vacuum towers include maintaining positive or negative pressure to check whether the pressure drop meets the requirements, as well as using soap foam tests for leak detection. 4. If a high level of vacuum is required, then a vacuum pump system must be used. I’m not sure what might be the cause of the periodic vibrations mentioned by the original poster ” What kind of vibration does periodic vibration refer to?
In the current process, there is a flash tower that uses a vacuum pump to create negative pressure, but the vacuum system experiences severe vibrations every 2-3 days. The pump body and motor show no significant abnormalities, but almost all pipelines are vibrating (the vacuum system is installed on a steel structure, not on a floor). Therefore, the vacuum pump needs to be restarted almost every 3 days, and the vibration disappears as a result. And then it repeats over and over again.
Upon asking the operators on site, it is suspected that the gas-phase pipeline at the top of the collection tank is too narrow, causing some liquid droplets to remain there; this results in back-and-forth movement of gas and liquid within the pipeline, leading to water hammer effects. After the pump is stopped, the liquid flows back to the collection tank, and the vibration disappears accordingly.
I think the same; it’s appropriate to add a bit of antifreeze