Hemp Drying Equipment
Hemp is one of the varieties of the Cannabis stevia plant species and is grown for its diverse industrial and medicinal uses. In the industrial sector it can be used to provide several commercial products such as paper, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, and animal feed. In the CDB sector it can used to provide tinctures, edibles, orals sprays, balms, salves and topicals.
The hemp drying process is a critical step and should begin as soon as possible after the plant is harvested to allow for the highest quality product.
Hemp from the field can typically contain anywhere between 10 and 20 percent moisture. The hemp industry has accepted 10% as an acceptable moisture level, but 8%-9% moisture is preferred. Temperatures of 150°-160° F are typically used for the 1st half of the drying process and then 120°-130°F to finish the drying process. The wetter the hemp, the more critical drying becomes and should be started within hours of harvesting.
Hemp drying is a crucial step in the process that is often overlooked. The hemp drying equipment chosen will determine the level of quality of the end-product. If hemp is dried quickly and efficiently it maximizes the fiber or medicinal product from the plants, but hemp that is harvested to wet or dried to slowly, can be contaminated by fungus or bacteria, ruining the product.
Different parts of the plant are typically used for different things. For hemp fiber typically the stalks are used, and removal of the flower heads is required prior to fiber processing. In the case of CBD almost all the CBD is in the flower heads with much smaller amounts in the leaves.
After harvesting high content CBD hemp, it should be dried immediately to prevent deterioration and ensure preservation.
There are numerous types of industrial hemp dryers designed for the size and type of operation. The following are the typical methods used in the industry:
- Batch – Typically used with rack systems, the chamber would use a heat source and fan for air recirculation. An exhaust system would be provided to remove the moisture from the chamber. Manufacturers offer standard sized units for smaller applications and custom engineered dryers for larger operations.
- Continuous – Typically used in high capacity farms or process situations. This type of oven would typically have a lead in load area, the actual drying chamber, and a lead out unload area. Conveyance would be provided by a mesh belt. An exhaust system would be provided to remove moisture from the chamber.
- Rotational Drying – This is a drum style drier with an auger type screw or plates internal to the drum to provide movement through the drum from the entrance to the exit and would include a heat source internal to the drum and an exhaust system pulling air from the drum housing.
Air flow is critical to drying hemp and cross flow (air flow from one side of the chamber to the other) or combination air flow (air flow from both sides of the chamber, return in the middle) are the desired methods for the batch processes. Each method has is positive and negatives and your specific application should be discussed with your hemp dryer manufacturer.
In continuous systems the preferred method would be top down, air is supplied above the product and conveyor and goes through the product and returns up the sides of the chamber (recirculated system), this provides uniform air flow along the length of the dryer.
Rotary dryers can have single pass heat sources (put heat into one end the chamber and push it out of the other end of the chamber) or recirculated heat sources (recirculate the heated air within the chamber). The disadvantage of single pass is that your natural gas or propane costs go up considerably. ITS recommends recirculated systems to minimize utility costs. A recirculated system would have an exhaust blower to remove moisture from the system. The rotary dryer can create a lot of dust from the continuous tumbling of the product and may require cyclone separators to remove the dust that could be exhausted from the system.
Industrial Cannibas Dryers are typically natural gas or propane fired units and they can be designed as indoor or outdoor units, or portable outdoor units (semi – trailer mounted) with outdoor units having weather enclosures. It can be quite common for an outdoor unit to have the load end of the drying chamber being located inside a building and the actual drying chamber being located external to the building.
The control systems for dryers can vary from push button and pilot light control and just set a desired temperature on a temperature controller, to a programmable logic controller with touch screen operator interfaces that can provide ramp and soak capability or continuous multizone, multitemperature units. Temperature data storage can be provided for those that want to document their process and provide that data to the end user. As the industry develops data acquisition will become more important as end users will be looking for a consistent product and the documentation that can be provided to show it.
Recipe controllers provide parameters that can be defined by the user, such as temperature, time, and the speed at with the air flow is controlled. Also, conveyor or drum speeds in continuous systems. These capabilities allow the user to develop and fine tune their own process.
Electrical Power requirements can be single phase 208volts to 240 volts but are typically three phase 208 volts to 480 volts. Control panels can be constructed to meet UL or CSA requirements if required.
Portable outdoor units electrical power sources are typically provided by a diesel generator mounted on the semi-trailer.
Currently International Thermal Systems only provides equipment to the fiber and CBD portions of the Hemp industry and would like to talk to you about your application.