Hemp is now benefiting from a resurgence in popularity thanks to high demand for CBD oil, and commercial items including paper, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed. It's interesting to note that hemp oil is selling for approximately $1000 per liter. Expectations of the global industrial hemp market is projected to balloon to over $10 billion dollars by 2025.
Legalized as part of the 2018 Farm Bill, the Bill changed hemp from a controlled substance to an agricultural commodity. Hemp cultivation is attractive to farmers who have been impacted by the increases in tariffs on certain crops. Consumer demand, along with higher profits for farmers, are causing explosive growth. Hemp can be grown for its seed, fiber, or floral biomass.
Harvesting and drying of hemp is critical for CBD production. The presence of molds and mildews will lower the value of hemp floral biomass, so the harvest needs to be stabilized before mold, mildew, or decomposing can occur. Once hemp is harvested, it should be immediately moved to the drying facility to eliminate the moisture content in the harvested hemp.
On a small scale, historically hemp has hung in a barn to air dry, an inefficient process – and a slow one. To keep up with consumer demand, a more modern and systematic approach for efficient harvest and drying is necessary, relying on industrial hemp dryers.
Optimally, drying should begin within hours of the harvest. The wetter the hemp, the more urgent the drying process should be. The hemp industry has accepted 10% moisture as dry. For higher product quality, and safety for long term storage, a preferred level is 8-9%. Most of the moisture in hemp comes from broken plant material, immature seeds, and seeds encased in bracts.
Batch dryers include drying chambers that usually are made up of a dehumidifier, an aerator, and a heat source. This product removes moisture out of a drying facility or a container. The energy efficient dehydration systems, designed to dry hemp, is a closed system that operates independently from ambient conditions. The combination of the heat driven dehumidification unit with a programmable controller that can be accessed remotely, plus airflow equipment creates consistent drying conditions inside the chamber.
The belt dryer has a conveyor into a large drying chamber. As dehydration is necessary to preserve the hemp biomass, mesh-belt hemp dryers continuously dry large quantities of plan materials in a short period of time, and without requiring much production footprint. These technologies allow the operator to adjust the thermal energy in the hemp dryer to evenly evaporate water without over drying or over heating the hemp. The fuel for belt dryers is via propane or natural gas. Designed for high output, the hemp dries as it advances through a collection of mesh layers. The use of electronic controls sets the stage for precise and optimum biomass drying conditions.
Rotary Dryers, the workhorse of industrial dryers, have been in use for many years. They also work well for drying hemp, typically via natural gas. Here’s how they work: the biomass is situated in a heated cylinder which rotates and tumbles the material, in the presence of drying air. The inside of the cylinder, or drum, includes plates to move the hemp. The electronic controls can be quite advanced, and these dryers can be very large. Again, they are designed to move large amounts of production throughput.
Irrespective of dryer type, temperature control is critical for maximum yield. Too much heat bakes the oil out of the hemp, wasting fuel and losing yield in the process. It is a delicate balance of maintaining temperature within a couple of degrees of setpoint, while moving green hemp through the dryer at the fastest rate possible. Goal is two fold - reduce moisture to 8-10% by weight without driving off the oil.