Hemp Activation/Decarboxylation in Steam Tube Dryers

Hemp Activation/Decarboxylation in Steam Tube Dryers

May 24, 2021 | Engineering

As part of our lifelong learning, Louisville Dryer Co. engineers regularly interact directly with processing industry customers and continue to make discoveries. Most recently, with changes in legislation for the burgeoning hemp industry and as the quantity of hemp to be processed has skyrocketed, entrepreneurs have reached out to technical experts in drying sciences and technology to help them explore their options for cost-effective solutions.

Hemp processors who were wanting to reduce their drying times by accurately controlling the drying environment consulted with Louisville Dryer Co. applications engineers.

As part of this endeavor, using our production-worthy scaled-down dryers in our Research & Development/Testing laboratory, we have engaged in leading-edge testing to determine which of their methods of processing and drying would perform the best for handling hemp.

In our Research & Development/Testing Laboratory, we use production-worthy scaled-down dryers to assist companies in developing new products such as wood composites, airbag propellants, rocket fuel, algae-derived oils, and more.

For an organic material such as hemp, a steam tube dryer is typically the ideal choice for the process since it allows for slow, even heating to remove internal moisture without scorching. Historically, a separate necessary step is the activation of the CBD-A as it exists in the hemp plant so that it is converted into the usable form CBD. This process is called activation or decarboxylation and makes the hemp’s chemical properties accessible for human bodies to process. The original understanding was that drying and decarboxylation were two separate steps and that they would need to take place in separate pieces of equipment to optimize each process.

Through hemp R&D experiments in our own testing laboratory, Louisville Dryer Co. engineers discovered that hemp dried in their Steam Tube Dryer went through the decarboxylation process: which is the necessary reaction where the organically present THCA or CBDA (from the cannabinoid-rich oil extracts) is converted into THC or CBD, which provides the consumer with the desired medicinal effects of the product.

What Louisville Dryer engineers observed in their laboratory and confirmed through independent testing was that decarboxylation can take place inside the steam tube dryer and is dependent upon the temperature and residence/dwell time of the material. In one of the tests, material was hand-harvested from a small local hemp farm and immediately taken to Louisville Dryer’s facility for processing.

Upon arrival, one of the first goals was to get the material to a manageable size that would make it through the steam tube dryer. Although a commercial unit can handle larger particles than the lab dryers, it is still valuable to know successful techniques for particle size reduction for instances when entire plants are being harvested.
Using a woodchipper, hemp flowers with some stems were chopped and collected. The resulting feed material was manually weighed and fed into the pilot steam tube dryer by hand. Through product material evaluation and testing, it was discovered that dryer material indicated a higher level of decarboxylation since lower product discharge moisture indicates higher material temperature. One of the major benefits is that the material can be activated and ready for use without it needing to be burned or further processed for decarboxylation to occur.
As hemp production needs increase, the next logical step for processors is to minimize the manual labor historically involved in smaller scale operations. For example, we have spoken with customers who still hang hemp in barns to dry in a similar manner to tobacco. This may work sufficiently for very small farms and acreage, but very quickly the costs and headaches of manually harvesting and hanging material become apparent on a larger scale.
In addition, there have been reports of improper ventilation that has led to product loss through molding. Another issue is the large footprint required for barns or similar buildings to hang hemp especially as the quantity to process increases. The steam tube dryer allows for material drying to take place in minutes and hours instead of days and weeks as with more traditional methods and naturally helps to prevent contamination of the hemp because of this and through less time spent handling/re-handling.

With decades of experience in the agricultural processing industry, Louisville Dryer Co. manufactures direct heat dryers for processing hemp and steam tube dryers with a range of capacities to dry wet hemp biomass with an output moisture content between 10-12%.

To learn which processing technologies would be optimal for your material and application, contact our team of Applications Engineers at (800) 735-3163 or fill out our online contact form.