Hydrocarbon Extractors

Solvent Recovery: Passive vs Active

Cannabis extraction is the process of separating the valuable compounds from the plant material, typically by using solvents such as hydrocarbons. The most common hydrocarbons used for cannabis extraction are butane and propane. Once the extraction process is complete, the solvent needs to be removed from the extract. There are two methods for solvent recovery: passive and active. In this blog, we will discuss the difference between passive and active recovery of solvent in cannabis extraction using hydrocarbons.

Passive recovery:

Passive recovery involves using heating and cooling to recover the solvent out of the extract solution. Heating the solution allows the butane or propane to change phases from liquid to gas, evaporating off of the cannabis / solvent solution. As the gas evaporates and rises, it meets the cooling side – in our case, a plate heat exchanger that is cooled using a chiller. When the hydrocarbon gas hits the heat exchanger, the gas is condensed back into a liquid. The liquid butane or propane is now “clean” and is sent back to solvent columns to be used in the next run of extraction.

One of the benefits of passive recovery is that it does not require any additional equipment like a gas compressor. Passive recovery is a very simple and straight forward process that takes place in the extractor with no additional steps or equipment outside of the extractor itself. This creates a very simple process for extractors and is easy to operate. Passive recovery is also a cheaper option, as recovery pumps typically add between $20,000-$50,000 in startup costs depending on the size of the extraction operation.

Active recovery:

Active recovery involves using additional equipment to remove the solvent from the extract. This method has been more popular historically, as it was thought of as faster than passive recovery. However, with the properly sized ancillary equipment, that’s not always true. H&H has used passive recovery methods since we released our first hydrocarbon extraction system after years of testing and working with thermodynamic engineers to develop the most affective designs and methods. In fact, more and more extraction companies are ditching the recovery pumps and offering passive extraction systems.

Active recovery is an efficient form of solvent recovery and is easily scalable, but as your operation scales in size, so will the price of the recovery pumps. Introducing additional equipment also means there is more equipment to maintenance, and recovery pumps often need repairs the more they are operated.

Which method is best?

The choice between passive and active recovery often comes down to operator preference. Since active recovery has been the go to method of solvent recovery in most of the closed loop extraction systems released over the last decade, most operators are more familiar with it and have generally preferred it based on comfortability and the idea that active recovery is faster. Many operators have never tried passive recovery, as the extraction systems they purchased did not support the recovery method in an efficient way.

With new developments in technology and the correct pairing of heating and chilling equipment, passive recovery can be a safe, efficient and cost effective solution for cannabis extractors. H&H has designed and manufactures two standard hydrocarbon extractors that both utilize passive recovery.

Passive recovery has become H&H Extraction Solutions’ standard method for solvent recovery because of its reduced up front costs and ongoing maintenance costs associated with solvent recovery pumps. We have put 3 years of research and development into the designs of our hydrocarbon extractors. With our experience in hydrocarbon extraction and our engineering team’s extensive research of thermodynamics and proper equipment pairings, we confidently offer efficient passive recovery hydrocarbon extraction systems. Reach out to us today to find out more!

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