Distillation is a unit operation and is widely used in the chemical industry. There are different types of the distillation process is used for the separation process which we had discussed in the previous article which also includes a definition of distillation. In the previous post, we had discussed what is vacuum distillation unit and the process in detail.
Among the types of the distillation process, vacuum distillation process There are various uses of vacuum distillation and benefits. Today in this article we will try to understand what are the selection criteria for vacuum distillation. Before we jump in to the tutorial, make sure your check what is distillation operation.
When vacuum distillation is selected
- Vacuum distillation is select when the product is heat sensitive and get decomposes at a temperature below boiling point. In such a situation vacuum distillation is used to separate/ remove selected solvent or compound from the product
E.g. Let us understand the purpose of vacuum distillation using an example.
- Suppose you have a product whose wet cake (after centrifugation) you need to dry it to remove traces of methylene chloride. The boiling point of MDC is 39.6 °C. But you know that the product is heat sensitive and it get degrade at 30 °C. So in this case, you will use a vacuum tray dryer in place of the tray dryer as the temperature required for the removal of traces of MDC in the vacuum tray dryer will be less the product degrade temperature i.e. 30 °C.
- If the temperature required for the distillation system is very high then, in this case, you can go for the use of vacuum distillation which will help you to use an economical utility like steam.
e.g. The boiling point of toluene is 110 °C hence if from the binary mixture, you need to distill out toluene then you need steam that can heat the compound upto 110 °C, but if you apply vacuum then toluene can recover at lower temperature.
- It reduces undesirable side reactions if taking place.
In some reactions, at high temperatures impurities present in the compound started to react and form side reactions. These side reactions can cause less decrease in product purity, affect the equipment and many more.
- The system requires fewer stages or a lower reflux ratio, as relative volatility increases with a decrease in operating pressure.
- It increases product recovery when dealing with maximum temperature constraints.
This was the article on when vacuum distillation is used and the application of vacuum distillation. Hope you had now a clear idea of When vacuum distillation is selected. If you have any problem then feel free to use the comment section and if you have some addition to the article then share with everyone by explaining in the comment section. If you are interested in learning chemical engineering concepts, then do check out how to read a pump curve. We also cover Industrial safety like hierarchy of controls osha. If you want us to cover any particular topic then do share with us in the comment section.