Passive and Active Solvent Recovery
When utilizing an extraction system that requires the use of solvent(s), the chosen solvent used in the extraction process is collected and recycled, by way of recovery. There are two types of recovery, active recovery, and passive recovery. The final product of each process is the same. However, there are some fundamental differences between active and passive solvent recovery that can affect different aspects of your manufacturing process.
Active solvent recovery
Active solvent recovery uses a gas compressor, often called ‘recovery pumps’ for the transfer of gaseous phase solvents. Recovering hydrocarbon solvents from the product involves heating the ‘slurry,” vaporizing the solvent which boils off at lower temperatures than the desired biomass (cannabinoids, terpenes, etc.) This vaporized, gaseous solvent then requires condensing back into a liquid state to be transferred into a solvent tank or cycled back into the process loop – ultimately to be reused. Active solvent recovery uses a mechanical pump to assist in compressing the vapor back to achieve this.
Passive solvent recovery
Passive solvent recovery on the other hand uses temperature differential, and temperature differential alone, to move and manipulate the solvent. This is normally achieved by using recirculating heaters and large chillers, and/or Carbon Dioxide or Nitrogen and as a consumable.
Passive Solvent Recovery
Pros
Quieter Lab Space
With passive systems, to maintain C1D1 compliance all the ancillary equipment is outside the C1D1 lab space making them quieter option for hydrocarbon extraction systems. Active systems utilize a compressor or ‘recovery pump’ that remains in the C1D1 lab space.
Cons
Higher Upfront Cost
High quality chillers and heaters are expensive. While more economic chillers are available they are also far more likely to bring your lab to a standstill down the road.
Higher Operating Costs
Chillers and heaters use large amounts of electricity, require regular consumable/maintenance expenditures, and aren’t user serviceable resulting in the need for HVAC professionals for most of the problems. Often when an ancillary piece goes down, the lab is down. All of this drives up the Cost of Goods Sold.
Gas Assistance Often Required
Often requires introduction of another gas, such as nitrogen, to aid in getting the solvent from one column to the next.
Active Solvent Recovery
Pros
Repeatable Consistent Results
Active solvent recovery offers consistent operation with repeatable results and is overall a far more efficient approach to recovering hydrocarbons. The ability to repeat procedures makes it easier to forecast everything from time to products and costs. Pumps are often user serviceable/rebuildable while chillers/heaters often require an HVAC professional.
Fail Points Eliminated
Active solvent recovery offers consistent operation with repeatable results and is overall a far more efficient approach to recovering hydrocarbons. The ability to repeat procedures makes it easier to forecast everything from time to products and costs. Pumps are often user serviceable/rebuildable while chillers/heaters often require an HVAC professional.
Can be added to improve recovery time on many legacy systems. For older hydrocarbon solvent recovery systems, the addition of a pump will increase the speed of solvent recovery, allowing for greater efficiency. Upgrading these legacy systems is a cost-effective way of increasing solvent recovery time without investing in an entirely new system. However, be mindful that your system is capable of keeping up with the compressor or “recovery pump” you plan on purchasing.
Cons
Certain ‘recovery pumps’ can be loud. Most ‘recovery pumps’ are repurposed equipment from other sectors of industry. Often users must rely on their Extraction System manufacturer to develop, distribute, and service the optimum solution for their systems’ solvent recovery.