Falling Film Evaporation

Falling Film Evaporation

April 20, 2020

Falling Film Evaporation: What is it and how does it work?

If you read our blog post about our extraction process, you’re familiar with our ethanol extraction method. But we want to look deeper into our removal process.

After our biomass has been extracted with ethanol, we remove the alcohol to produce our crude hemp oil. Falling film evaporation allows us to produce high-quality crude hemp oil at a much lower cost than nearly any other solvent-removal method currently available. Using gravity, evaporation, condensation and gentle heat under a vacuum, the falling film evaporator is the most efficient choice for removal. Along with the time it saves, the relatively low temperatures our extract is exposed to, and the amount of alcohol we can recover to reuse on our next extraction, it’s also the most cost effective.

Falling film evaporators have actually been around for quite a while, serving use in industries such as sea water desalination, food and dairy processing, oil refining and in the production of industrial agricultural fertilizers. Here at Botanical Solutions, the falling film evaporator is the key piece of equipment that keeps our process efficient. Without it, production would continually bottle-neck at this crucial step in the extraction process.

So, how does it work? 

First, our freshly extracted, filtered hemp and alcohol solution (often called the mother liquor) are pumped into the first chamber of the evaporator, called the pre-warmer. This chamber warms the room-temperature alcohol a bit closer to its boiling point for the sake of efficiency. Next, the warmed alcohol is pulled up several feet vertically to the top, or head, of the evaporator. From here, spray nozzles ensure the even distribution of the liquid into a group of small vertical tubes. As the mother liquor begins to cascade downward, it creates a very thin film on the inside surface of each tube. These tubes are gently heated at the right temperature to evaporate the alcohol as the solution falls several feet back down toward the base. This allows the crude hemp oil to fall to the collection vessel at the bottom, while the alcohol vapor is whisked into a separator vessel. There, it is cooled and condensed back into a liquid to be collected and reused for our next extraction.

This entire process is done under a vacuum, which reduces the boiling point of the alcohol, as lower temperatures are crucial for preserving the integrity of our cannabinoids and terpenes. Once the run is complete, the still-warm crude hemp oil is removed from the collection vessel and is ready for the next step in our process: winterization.

If you’re curious about our complete extraction process, learn more here.

Image courtesy of GEA. Please note that this is not the exact piece of equipment we use.

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