Versatile Low Temperature Short Contact Distillation

by | Aug 10, 2018

Versatile Low-temperature short-contact distillation and other extraction techniques are utilized to separate bioactive components from cannabis plants, removing them from the plant matrix. These techniques are commonly employed to isolate specific desirable compounds.

For centuries, the cannabis (marijuana, hemp) plant has been used for medicinal purposes. It contains terpenes, flavonoids, and over 100 types of therapeutically active compounds known as cannabinoids. Among these, the most well-known are tetrahydrocannabinol (THC) and cannabidiol (CBD).

CBD is non-psychoactive and has been clinically demonstrated to have analgesic, antispasmodic, anxiolytic, antipsychotic, antinausea, and anti-rheumatoid arthritic properties. THC, on the other hand, is psychoactive and is commonly used recreationally. However, it is also an extremely potent therapeutic compound, particularly beneficial for cancer patients in reducing nausea, vomiting, pain, and stimulating appetite.

The Importance of Nonselective Extraction Method

Due to the significant synergy between different cannabinoids and terpenes, it is highly recommended to utilize natural cannabis-based preparations rather than single purified or synthetic cannabinoids. Therefore, a nonselective extraction method is advised.

Concentrated extracts of cannabis plants, such as shatter, crumble, budder, wax, and oil, have gained popularity due to their convenient routes of administration. These extracts are viscous and sticky substances produced through solvent extraction using solvents like petroleum hydrocarbons, subcritical or supercritical CO2, and alcohols. Solvent evaporation yields a potent concentrate.


Versatile Low Temperature Short Contact Distillation


What is Molecular Distillation?                 

Once the Solid-Liquid extraction is completed, the miscella is collected in a tank. This miscella contains all the phytochemicals of the cannabis plant and the solvent/solvent system. This miscella is taken from the evaporation through the forced circulation evaporator and molecular distillation system.

Depending upon the miscella volume, one can have a single stage, double stage or multiple stage system. In forced circulation evaporation, the miscella is circulated through tubes or tube bundles which are enclosed in a shell at high pressure by means of a pump. Steam is introduced into the calendria to heat the miscella in the tubes or tube bundles.

A pump sends the liquid to the tube with a positive velocity. As the liquid moves up through the tube, it gets heated and begins to boil. As a result, the vapor and liquid mixture rushes out of the tubes at a high velocity. Forced circulation of the miscella creates some form of agitation.

When the miscella leaves the tubes and enters the vapor head, the pressure falls suddenly. This mixture strikes the deflector to effective separation of liquid and vapor. This leads to the flashing of super heated miscella. Thus the evaporation is effected.

The vapor enters the cyclone separator and leaves the equipment through a condenser. The solvents thus collected shall be reused for the next cycle of extraction. The concentrated liquid enters the pump for further evaporation. Finally, the concentrated product is collected.

Solvent Recovery and Concentration

Sufficient liquid height (submergence) is maintained above the liquor inlet on the vapor body and above the heat exchanger tubes to suppress mass boiling in the inlet and prevent boiling at the tube surface. This is necessary to prevent precipitation in the tubes which would lead to fouling of the heat transfer surface

A high circulation rate is provided for adequate tube velocity to achieve good heat transfer. Therefore, lower temperature rises are assured which minimize super saturation of the solution.

The output of forced circulation evaporation is concentrated miscella, which contains a high amount of cannabis phytochemicals. This is further concentrated in the molecular distillation unit.

Molecular Distillation Method

Molecular distillation is an advanced vacuum distillation method performed by short-path evaporators. The distance between the evaporator and condenser is extremely reduced, which results in minimized pressure drop. Heat-sensitive material meets heat for a short time under high vacuum, thus low, or no decomposition occurs.

Molecular distillation is considered the safest mode of separation and to purify the thermally unstable molecules and related compounds with low volatility and elevated boiling point. The process distinguishes the short residence time in the zone of the molecular evaporator exposed to heat and low operating temperature due to vacuum in the space of distillation.

The molecular distillation process is carried out at a very low pressure so that the distance between hot and condensing surface is less than the mean free path of the molecules. The number of stages of molecular unit integration depends on the volume of miscella to be processed.

Molecular distillation is applied to thermally sensitive high molecular weight materials (range of 250 – 1200). The molecular weight of cannabinoids is 628.938; THC 314.45, Cannabidiol 314.46). The contact times in commercial units may be as low as 0.001 seconds. The film thickness is of the order of 0.05 – 0.1 mm which is created by suitable vipers that are rotated on the cylindrical vessel.

A molecular distillation unit has a feed distributor, which distributes the miscella evenly as a thin film by the vipers, which increases the evaporation surface. The evaporated solvent is condensed in the internal condenser using chilled water and the thick/concentrated miscella is sent out by means of the vipers.

The solvent/solvent system is collected through an external vent condenser and used to extract further materials. The highly concentrated cannabis extract is thus collected for further processing or direct usage.

This method gives a highly bioactive cannabis extract which contains intact cannabis phytochemicals as the overall process sequence is done in low temperature and short residence time with heating elements.

High Bioactivity and Process Benefits

The entire low-temperature short-contact distillation path process is controlled by PLC-SCADA software with all process control systems like temperature control, flow control, vacuum control, and product viscosity. This ensures the quality and consistency of the final product. Additionally, molecular distillation also allows for easy scale-up and customization for different extraction needs.

Solvent-based Extraction Techniques

Several common forms of cannabis extraction rely on solvents. In these methods, the cannabis plant material is soaked in a solvent or solvent system, the plant material is then removed, and the liquid is filtered. The solvent is subsequently removed through evaporation.

Importance of Solvent Removal

Regardless of the extraction method, it is imperative to remove solvents to obtain highly concentrated extracts with significant pharmacological effects. These extracts can be easily formulated into drug delivery routes. Separation techniques, including conventional distillation, are used to extract heat-sensitive compounds from herbs. However, caution must be exercised as some compounds may have high boiling points that can adversely affect other compounds.

We, at Clean Green Biosystems, developed a PLC-SCADA based method of separating the bioactive molecules from herbs and from cannabis, called Low-Temperature Short Contact distillation path, which is a combination of forced circulation evaporation and molecular distillation process.

Advancements in Short-Contact Distillation and its Applications

Overall, low temperature short-contact distillation is a highly versatile technique that offers numerous benefits in the purification and separation of liquids. Its low-temperature conditions make it suitable for a wide range of applications and its efficiency and cost-effectiveness make it a valuable tool in various industries. With advancements in technology, this method will continue to evolve and play a significant role in the production of high-quality products.

Moreover, short-contact distillation is constantly being improved upon and refined, leading to new variations such as flash distillation and molecular distillation. These advancements have made it possible to separate even more complex mixtures with higher precision, opening up possibilities for industries that require highly pure or specific components.