20 Liter Short Path Distillation

How 20 liter short path distillation works:

The driving force for steam flow is the pressure difference between the boiling film and the condensing surface, and a small pressure drop will cause the flow of steam. Operating at 1mbar and requiring a shorter distance between the boiling surface and the condensing surface, the distiller made according to this principle is called a short-path distiller. The short path still (molecular distillation) has a built-in condenser opposite the heating side and brings the operating pressure down to 0.001 mbar.
 
20 liter short path distillation is a thermal separation technology process working at a pressure of 1~0.001mbar. Its lower boiling temperature is suitable for heat sensitive and high boiling point substances. Its basic composition: a cylindrical cylinder with a heating jacket, a rotor and a built-in condenser; a film wiper and an anti-splash device are precisely installed on the fixed frame of the rotor. The built-in condenser is located at the center of the evaporator, and the rotor rotates between the cylindrical shell and the condenser.
 
The distillation process is: the material is added from the top of the evaporator, and is continuously and evenly distributed on the heating surface through the material-liquid distributor on the rotor, and then the film scraper scrapes the material liquid into a thin, turbulent liquid film. and spiral downwards. During this process, the light molecules escaping from the surface of the heating surface condense into a liquid on the built-in condenser through a short route and almost without collision, and flow down the condenser tube, passing through the condensate at the bottom of the evaporator. The discharge pipe is discharged; the residual liquid, that is, heavy molecules, is collected in the circular channel under the heating zone, and then flows out through the discharge pipe on the side.
 

The process of 20 liter short path distillation can be divided into the following four steps:

1. Molecules diffuse from the liquid phase body to the evaporation surface

Usually, the diffusion speed in the liquid phase is the main factor controlling the molecular distillation speed, so the thickness of the liquid layer should be reduced as much as possible and the flow of the liquid layer should be strengthened.
 

2. Free evaporation of molecules on the surface of the liquid layer

The evaporation rate increases with the increase of temperature, but the separation factor sometimes decreases with the increase of temperature. Therefore, the thermal stability of the substance should be taken as the premise to choose an economical and reasonable distillation temperature.
 

3. Molecules fly from the evaporating surface to the condensing surface

In the process of flying from the evaporating surface of the molecular still to the condensing surface, the vapor molecules may collide with each other or with the air molecules remaining between the two surfaces. Because evaporated molecules are much heavier than air molecules, and most of them have the same direction of motion, their own collisions have little effect on the direction of flight and evaporation speed. The residual gas molecules are in a chaotic thermal motion state between the two sides, so the number of residual gas molecules is the main factor affecting the flying direction and evaporation speed.
 

4. Molecules condense on the condensation surface

As long as there is a sufficient temperature difference between the hot and cold sides of the molecular still (generally 70~100°C), and the form of the condensation surface is reasonable and smooth, the condensation step can be completed in an instant, so it is very important to choose a reasonable form of condenser.

Precautions

1. Pay attention to certain operating procedures during operation, so as to avoid improper operation that may cause the entire equipment to be unusable, and the supporting Wuxi Shengze refrigeration and heating temperature control system cannot be used.
 
2. Before leaving the factory, 20 liter short path distillation generally undergoes hydraulic test and trial operation, and all indicators meet the requirements. Start the motor and observe whether the motor is running in the correct direction. It should rotate clockwise, not reversed. Measure whether the radial swing and axial transmission of the shaft meet the requirements, and check whether the seal is tight. Whether the oil level of the reducer is normal and whether the cooling water of the mechanical seal is kept unimpeded.
 
3. The normal shutdown sequence of 20 liter short path distillation is: close the steam valve, close the feed valve, close the discharge valve, flush the equipment, stop the motor, stop the circulating water pump, jet pump, and open the vacuum breaking valve after the feed liquid is exhausted.
 
4. When the equipment has no material liquid or the liquid material is full, the motor cannot start stirring. It is strictly forbidden to reverse the motor. When running, do not touch the rotating parts with your hands. Do not press the button with wet hands to prevent electric shock.
 
5. Try to pay attention to some safety knowledge during the operation to avoid some safety accidents, because safe production is very important.
 
FBL has extremely specialized professionals who are always ready and can help you with all your 20 liter short path distillation related issues. We sincerely look forward to your visit.

---