BULK HANDLING EQUIPMENT & SYSTEMS

HEMP

Overview:

Industrial hemp is a strain of Cannabis Sativa, a renewable resource cultivated primarily for its fiber, flowers and seeds. One of the oldest known domesticated crops, it has been used for making paper, textiles and rope for thousands of years.

Today, hemp is used in a myriad of products. The seeds and flowers are incorporated into foods, beauty products and nutraceuticals, while the fibrous stalk is used in the production of cordage, carpet, clothes, insulation, animal bedding, non-wovens, concrete, biodegradable packaging, biofuel and more.

While sharing a common cannabis ancestry with marijuana, hemp contains less than 0.3% of the psycho-active agent THC found in marijuana. Similar in appearance, the plants differ in their genetic make-up, uses and cultivation methods.

Despite these differences, however, hemp was included in many pieces of legislation introduced at the state and national level to strictly regulate the cultivation and sale of all cannabis varieties, and was included in the 1970 Controlled Substances Act as a Schedule 1 drug.

The 2018 Farm Bill, passed by the United States Congress and signed into law by President Trump, legalized hemp production in the United States as an agricultural commodity, and removed it from the list of controlled substances.

The hemp plant has a woody core fiber known as "hurds," surrounded by a layer of soft pith, with a tough outer layer consisting of bast fibers. The commercial markets for bast fibers include specialty textiles, paper and composites. Hurds are used for garden mulch, animal bedding, and fuel. When mixed with other materials, hurds can be fashioned into concrete-like building materials, composites, and fiberglass alternatives used in the auto and aviation industry.

Hemp seeds are pressed to extract oil, cannabidiol, known as CBD which is purported to have medicinal uses. Hemp seed oil is also used in paints, varnishes,
nutraceuticals personal care products, and food supplements. The seeds can be ground into flour, and used in animal feed.
 
 
Characteristics and Challenges:

Consultation with an experienced material handling systems engineer is recommended when considering a hemp conveying solution. In powder form, hemp is generally 180 microns in diameter and has a bulk density between 12 to 18 lb/cu ft (192 to 288 kg/m3). Common challenges encountered when conveying hemp powder include bridging and rat-holing of the material, resulting in poor or nonexistent material flow in the convey line. Traces of the oil remaining in the hemp powder can cause the material to pack or cake and leave a non-lubricating residue on the convey line.

Hemp seeds are approximately 0.125 in. (3 mm) in diameter. These are free-flowing and can flood conveying lines. They are also friable and may require lower-speed, gentle conveying systems to avoid degradation. Hemp stalks and flowers have irregular shapes and bulk densities, generally falling in the 10 to 12 lb/cu ft (160 to 192 kg/m3) range. Lightweight and compressible, stalks and flowers tend to interlock during shipment and storage, and can be difficult to evacuate from IBCs (Intermediate Bulk Containers) with narrow openings. Care must be taken to ensure that the stalks are of the proper length and moisture content as to not bind moving components or plug convey lines.

When hemp is used as a food or personal care additive, the equipment used to process it should meet all regional, national and international standards for food handling design, construction and operation.

If the hemp is being pneumatically conveyed into a processing system, the blower used to move hemp through the air line must be sized to meet the demands of system. If a flexible screw is being used to convey hemp, a screw with a wider, flatter surface than the standard-sized screw is recommended.

Hemp
 

For hemp being unloaded from bulk bags, a secure, dust-tight connection between the bag spout and the equipment inlet that creates a sealed system is recommended. Equipment purpose-built for flow promotion should be applied to aid in the full evacuation of hemp from the bag. These include spring-loaded frames that stretch the top of the bag upward as it empties and elongates, causing hemp to flow from the corners of the bag, and pneumatically-actuated flow promotion devices that massage the bag and direct non-free-flowing hemp into the bag spout. To prevent the escape of dust in the event of a leak and/or when incoming hemp displaces air, the sealed system can be vented to a dust collector that puts the entire system under vacuum. This provides the added benefit of collapsing empty bags prior to tie-off and removal, preventing dust generated when empty bags are flattened manually.

Feed hoppers should be designed with proper geometry and may need to incorporate devices such as vibrators to aid in the flow of the hemp. A hopper screen above the receiving vessel will help protect the operators if the hemp is being dumped manually into a hopper that is equipped with agitating devices.

When filling bulk bags with hemp, dust can be contained by making secure connections between the material feed source and the bulk bag filler inlet. The sealed system is vented to a filter sock or optional dust collection system to prevent displaced air and dust from entering the plant environment. The use of vibratory densification decks will greatly maximize the capacity of the bulk bags during the filling process, while load cells and programmable gain-in-weight controls can greatly reduce cycle times and increase weighing accuracy.

Flexicon Applications:

High-capacity Flexicon BEV-CON™ conveyors are equipped with screws having specialized geometries capable of moving hemp, which can be non-free-flowing and otherwise difficult-to-handle.

FLEXI-DISC® Tubular Cable Conveyors can gently and efficiently slide fragile hemp seeds and hemp hearts through smooth stainless tubing using low-friction polymer discs attached to stainless steel cable, moving the material to and from storage or process equipment horizontally, vertically or at any angle to single or multiple discharge points.

Flexicon's Single-Trip Bulk Bag Discharger features an electric hoist and trolley that raises bulk bags of material from floor level to the inside of a safety frame, and then lowers the bag bottom onto a four-bladed knife mounted on the receiving hopper. This application is idea for single trip bulk bags that contain compressible, hard-to-remove materials including hemp.

A Flexicon Sanitary High Lift Box Dumper with Vibratory Bin Feeder is ideally suited for emptying Gaylords of material into downstream processing equipment. The receiving hopper can be rolled to another processing station or to a wash-down area for complete cleaning.

Flexicon's sanitary TWIN-CENTERPOST™ bulk bag filler is the first of its kind to receive USDA acceptance. The patented design maximizes strength and improves accessibility to bag hooks while simplifying construction and reducing cost. It is available integrated with a Flexicon conveyor engineered to transport hemp.

 
Sources: Where noted. All other information courtesy of Flexicon Corporation.