Large scale 50L cheap rotary evaporator
The basic structure and principle of the rotary evaporator:
The distillation flask is an eggplant-shaped or round-bottomed flask with a standard ground mouth interface. It is connected to a pressure-reducing pump through a high reflux serpentine condenser tube. The other opening of the reflux condenser tube is connected to a receiving flask with the ground mouth. Receive the evaporated organic solvent.
There is a three-way piston between the condenser tube and the decompression pump. When the system is in communication with the atmosphere, the distillation flask and the wetted flask can be removed to transfer the solvent. When the system is in communication with the decompression pump, the system should be in decompression. When using, the pressure should be reduced first, and then the motor should be turned on to rotate the distillation flask. When it is finished, the machine should be shut down and then vented to the atmosphere to prevent the distillation flask from falling off during rotation.
As a heat source for distillation, it is often equipped with a corresponding constant temperature water tank. Through electronic control, the flask is rotated at a constant speed at the most suitable speed to increase the evaporation area. The evaporation flask is under negative pressure by means of a vacuum pump. The evaporating flask is placed in a water bath for constant temperature heating while rotating, and the solution in the bottle is heated, diffused, and evaporated in the rotating flask under negative pressure. The rotary evaporator system can be sealed and reduced to 400-600 mmHg; the solvent in the distillation flask is heated with a heating bath, and the heating temperature can be close to the boiling point of the solvent; it can also be rotated at a speed of 50-160 rpm, Make the solvent form a thin film and increase the evaporation area. In addition, under the action of the high-efficiency cooler, the hot vapor can be quickly liquefied to accelerate the evaporation rate.
Safety risk assessment of rotary evaporator used in distillation extraction:
The safety risk of distillation mainly comes from the solvent and heating medium of the distillation.
1) If the heating medium is silicone oil, the ignition point is at least 25°C higher than the maximum temperature of the heating pot.
2) If the distillation solvent is flammable and explosive, explosion-proof glass components can be used as the first choice. After the distillation is completed, it is best if the instrument can automatically deflate, so as to avoid manual deflation too fast and cause an explosion.
3) To optimize the laboratory environment, a secondary condensation device can be selected to maximize the recovery of the distillation solvent.
Regarding the vacuum degree of the rotary evaporator:
Vacuum is the most important process parameter of rotary evaporator, and users often encounter vacuum problems. This is often related to the nature of the solvent used. In biochemical and pharmaceutical industries, water, ethanol, acetic acid, petroleum ether, chloroform, etc. are commonly used as solvents, and general vacuum pumps cannot withstand strong organic solvents. Special vacuum pumps with strong corrosion resistance can be selected. Water circulation vacuum pumps are recommended. .
The method to check whether the instrument is leaking: pinch off the external vacuum hose and observe the vacuum gauge on the instrument to see if it can be kept air-tight for five minutes. If there is air leakage, check whether the sealing joints and the sealing rings on the rotating shaft are effective. On the contrary, if the instrument is normal, check the vacuum pump and vacuum pipeline.
