Selection of a pilot distillation column
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Help: I am performing vacuum distillation; the boiling points of the two components differ by 20°C under vacuum, and the temperature at the bottom of the column is 154 degrees. In the original experiment, 800 g of material was processed at a time using a distillation column with a length of 20 cm. Now I need to process 3000 g at a time, which means using a three-necked flask with a capacity of 5000 ml; the material is added all at once. Do the height and diameter of my distillation column need to change? If it doesn’t change, will it overflow? I mainly want to know how to choose a distillation column Thank you
If the material composition remains unchanged, it will not affect the height. The diameter is determined by the processing volume; if you continue to steam at the original speed, there is no need to increase the diameter. If you increase the steaming speed, you may need to increase the diameter.
Thank you. How much material is appropriate to fill in a 5L three-necked flask? Also, if the distillation column remains unchanged, could it cause flooding? Seeking advice
For distillation experiments, it is best to keep the filling level of the flask at 40-60% (to prevent bubbling or splashing due to boiling). Regarding the height and diameter of the distillation column, the answer on the second floor was very clear: the height is determined by the composition of the material and the required separation precision ； The diameter is determined by the distillation rate (evaporation rate); if the distillation rate is controlled in the same way as in the original experiment, the original distillation column can be used. However, in practice, since the size of your flask has increased, which means the heating area has grown as well, the amount of evaporation will surely increase. Therefore, the diameter of the distillation column should be chosen to be larger accordingly. The basis for selecting the diameter is to calculate the empty tower gas velocity using the evaporation rate from the original experiment and the diameter of the distillation column; then, select a diameter that results in the same gas velocity based on the evaporation rate from the scaled-up experiment ； Tower height: Although the material composition and distillation precision remain unchanged, the tower height can also stay the same; in reality, however, a suitable height-to-diameter ratio must be taken into account for distillation towers. This is especially true for small experimental towers, where wall effects are present; therefore, as the diameter increases, the height also needs to be increased! That’s all.
I’ve learned it. Thank you for your guidance :handshake