Vacuum pump vacuum distillation process is widely used in petrochemical industry. Compared with atmospheric distillation, it has many characteristics: lower boiling point; less danger of decomposing polymer, low temperature treatment of vacuum pump; easy heating and less heat loss; less influence of oxygen and steam in air on volatility; change of equilibrium relationship (such as azeotropic point disappearance). But it also has its shortcomings: low temperature is required for condensers and traps; heat transfer mode has certain requirements; equipment and operation costs are relatively large. For external pressure vessel, snake tube or jacket heat exchanger is usually used to heat with steam or oil.
In order to improve the heat transfer, most tanks are equipped with agitators, and raw material preheaters or forced circulation heaters can also be installed. The heating, degassing and distillation of raw materials are carried out in the tank. Condenser usually chooses tubular condenser (steam shell-walking distance) and rotary plate condenser (steam straight passage). Condensers and distillation tanks are usually separated. But sometimes it can be directly placed on the top of the distillation tank to form a whole. Because the gas coming out of the condenser includes the vapor at the condensate temperature and the non-condensable gas, some vacuum pumps are not suitable for extracting these vapors.
In order to protect vacuum pumps and capture distilled substances, mechanical traps, cryogenic traps or adsorption traps are often used. The mechanical traps are centrifugal (cyclone type, swirl plate type), collision type (baffle type, umbrella type, baffle type, etc.) and air filter type (wire mesh filter, dry filling type, etc.).
The continuous distillation unit is between the batch distillation unit and the distillation unit. Compared with the batch distillation unit, the continuous distillation unit has no long high temperature heating part and has high thermal safety. In addition, the unit has a small capacity, can operate continuously and has a certain degree of distillation effect. Because it is limited by preheating and residence time, it can only be used in situations with high relative volatility and good separation. Generally used for degassing, dehydration, solvent removal and deodorization operations.
2SK Liquid Ring Vacuum Pump
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