n-butane stripping column
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What’s causing the olefins at the top of our n-butane column (Column 5)? Is it caused by the reaction? Is it still produced during the distillation process? Is it due to incomplete reaction, or are they products of the reverse alkylation cleavage reaction? I would appreciate your advice.
One reason is that the material from ahead moves along with the cyclobutane; mainly, there is no check valve in place. Another reason is incomplete reaction – during distillation, no chemical changes occur that would produce olefins
Other issues have been analyzed; the reaction may not be complete, or there could be leaks in the heat exchangers for the products and raw materials – the latter possibility is more likely. It is recommended to check the latter! ! ! !
In the subsequent process, there is little heat exchange between the raw materials and the feed to the n-butane removal tower. This situation is mainly caused by the reactions that take place earlier. If the amount involved is very small, such as a few dozen ppm, then it’s not a concern – it might be due to analytical errors. However, if it’s several percent, that’s a problem. Additionally, if there is an abnormal acid consumption, then the only option is to shut down the plant and investigate the reactor.
The heat exchanger used for heat exchange between the reaction products and the raw materials may have leaks; if what Haiyou mentioned is several dozen PPM, it could indeed be an issue with the laboratory analysis – a self-check of the laboratory standards is needed. We also encounter issues with laboratory tests related to olefins; these are relatively rare but are sometimes overlooked.