Distillation is the partial gasification of liquid mixture, using the different characteristics of each component volatility to achieve the purpose of separation. Before using roots vacuum pump in distillation process, the following problems exist: longer distillation time, more than 12h / batch; many distillation residues. The reason is that the amount of coking resin after distillation is relatively large due to the long time used in the distillation process and the high distillation temperature. So how to solve this problem? The following will introduce the classification of distillation process and the application of Roots vacuum pump in distillation process.
Distillation processes are generally classified as follows:
1. According to the quantity of components in the distilled mixture, it can be divided into binary distillation and multiple distillation.
2. According to whether the operation process is continuous, it can be divided into batch distillation and continuous distillation.
3. According to the working pressure, it can be divided into atmospheric distillation, pressure distillation and vacuum distillation.
4. According to the operation mode, it can be divided into simple distillation, balanced distillation and distillation.
5. According to some special requirements of separation system, distillation also includes steam distillation, batch distillation, azeotropic distillation, extractive distillation, reactive distillation, etc.
Distillation is a thermodynamic separation process. It uses different boiling points of components in mixed liquid or liquid-solid system to evaporate components with low boiling points, and then condenses to separate the whole component. It is a combination of evaporation and condensation operation units. Compared with other separation methods (such as extraction, filtration and crystallization), it has the advantage that it does not need to use other solvents other than system components, so as to ensure that no new impurities will be introduced.
In order to solve the above problems, after analysis and research, I think it should be considered from the perspective of improving the vacuum degree. In theory, high temperature will accelerate the Resinification of materials, while a longer residence time of materials will increase the amount of resin. Improving the vacuum degree in the pot is undoubtedly the best way to solve the two problems of long distillation time and excessive distillation residue.
First, the boiling point of the material can be reduced after increasing the vacuum degree, that is, the foaming point temperature in distillation operation can be reduced. Secondly, increasing vacuum can increase the driving force of distillation and accelerate the evaporation rate of materials.
In the distillation process, the vacuum equipment we used in the past is the ordinary oil-free vacuum pump. Now the method is to use the high vacuum of Roots vacuum pump in series with oil-free vacuum pump. We know that the oil-free vacuum pump sucks into the system. It is the exhaust gas of Roots vacuum pump. With the help of roots pump, the vacuum degree on the protection box is greatly improved, and the vacuum degree is almost – 0.1MPa when running without load.
It has been proved in practice that when roots vacuum pump is used in distillation process, high vacuum is conducive to the evaporation of magnesium chloride and magnesium, and also to reduce gas pollution. In the later stage of vacuum distillation, the vacuum degree is not more than 0.013pa. At the same time, it can improve the recovery rate and increase the recovery. In addition, the use of Roots vacuum pump and oil-free vacuum pump in series can effectively shorten the operation time and reduce the resin residue, thus reducing the raw material consumption of the product.
Roots vacuum pump in distillation process