Why Use Short Path (Molecular) Distillation

As an efficient and new green separation technology, molecular distillation successfully avoids the defects of traditional separation and extraction methods because of its low temperature and short heating time. Especially in the separation, purification and concentration of natural products, distillation of heat-sensitive products and other aspects, such as complex and heat-sensitive substances, such as vitamins and polyunsaturated fatty acids. Short path molecular distillation device is used for distillation, concentration, desolventization, stripping, reaction, degassing, deodorization (gas) and other purposes, and good results have been achieved.

Short-range molecular distillation is a thermal separation process, which is specially used to separate heat-sensitive products. It is characterized by short product residence time and low process evaporation temperature, and strives to make the distilled product suffer as little thermal stress as possible. Short-distance distillation with vacuum system can significantly reduce the boiling point of the product by reducing the operating pressure.

Working Principle

Based on the pressure difference between boiling film and condensation surface, it is the driving force of steam flow direction. Running at 1mbar requires a very short distance between the boiling surface and the condensation surface. The short-path distiller (molecular distillation) has a built-in condenser opposite to the heating surface and reduces the operating pressure to 0.001mbar.

The Process

The material is added from the top of the evaporator, 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 very thin, turbulent liquid film, and pushes it downward in a spiral shape. In this process, the light molecules escaping from the heating surface condense into liquid on the built-in condenser after a short route and almost no collision, and flow down the condenser tube and are discharged through the discharge tube at the bottom of the evaporator; Residual liquid, that is, heavy molecules, is collected in the circular channel.

The Conditions

• Diffusion of molecules from the liquid phase to the evaporation surface: Generally, the diffusion speed in the liquid phase is the main factor to control 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.
• Free evaporation of molecules on the surface of liquid layer: The evaporation rate increases with the increase of temperature, but the separation factor sometimes decreases with the increase of temperature. Therefore, the economic and reasonable distillation temperature should be selected on the premise of the thermal stability of the processed substance.
• Molecules flying from the evaporation surface to the condensation surface: In the process of flying from the evaporation surface to the condensation surface, vapor molecules may collide with each other or with air molecules remaining between the two surfaces. Because evaporation molecules are much heavier than air molecules, and most of them have the same direction of motion, their own collision has little effect on the flying direction and evaporation speed. However, the residual gas molecules are in chaotic thermal motion between the two surfaces, so the number of residual gas molecules is the main factor affecting the flying direction and evaporation rate.
• Molecules condense on the condensation surface: As long as there is enough temperature difference between the hot and cold surfaces (generally 70~100℃) and the condensation surface is reasonable and smooth, it is considered that the condensation step can be completed in an instant, so it is very important to choose a reasonable condenser form.

Advantages

1. High separation accuracy: Short path molecular distillation can achieve efficient separation, and high-purity products can be obtained through accurate control system.

2. Mild separation conditions: It is carried out at a lower temperature, so thermal decomposition and oxidation reactions caused by high temperature can be avoided, and the stability of the separated substances is protected.

3. Fast separation process: The molecular distillation has short distillation process time, which can save time and energy and improve production efficiency.

4. Suitable for many kinds of substances: Distillation can be used to separate many kinds of mixtures, including substances with high boiling point, heat sensitivity, easy oxidation, emulsification and so on.

5. High degree of automation: The distillation equipment adopts advanced control system and automation equipment, which can reduce manual operation and human error and improve the stability and reliability of separation process.

6. Environmental protection and energy saving: The machine used in short-distance molecular distillation is compact, which reduces the waste of energy. At the same time, all the materials used are environmentally friendly and have little impact on the environment.

Types

• Short-distance molecular distillation with rolling film: This type of distillation equipment uses rolling film to scrape off bubbles and droplets on the surface of liquid film, thus obtaining relatively pure light components.
• Sliding scraper short-distance molecular distillation: The distillation equipment adopts sliding scraper, which can effectively control the thickness of liquid film and enable heavy components to be effectively stripped.
• Hinge scraper short path molecular distillation: It adopts hinge scraper, which can better adapt to the change of materials and the size of throughput, and has higher flexibility.

Applications

Flavors and fragrances: Tobacco flavor, rose essential oil, orange peel oil, cypress oil, agarwood, dragon sialyl ether, perilla alcohol, sweet orange oil, pepper oil, ginger oil and other food flavoring agents;

Food and health products: MCT oil, walnut oil, seabuckthorn seed oil, Acer truncatum oil, Ganoderma lucidum spore oil, monoglyceride, VE, fish oil, carotene, etc.

Medicine: Synthesis of pharmaceutical intermediates, pharmaceutical monomers, and refining of drugs extracted from plants;

Petrochemical industry: Polyol ester lubricating oil, silicone oil, regeneration of waste smooth oil, polyacid grease, polyalkene, high temperature heat transfer oil, aviation lubricating oil;

New materials: Epoxy resin, liquid crystal material, OLED material, lithium battery additive, PI flexible material, adhesive, waterproof material and plasticizer.

ACHIEVE CHEM has a laboratory to do verification tests for your samples and products, we provide short path molecular distillation selection through experimental demonstration, and make equipment suitable for product technology.