PROCESSWEST Magazine Online

How flexible screw conveyors improve productivity

March 2, 2021   Don Horne




Manitoba Harvest is a major producer of hemp hearts, hemp powder, hemp granola, hemp bars, hemp extract and other hemp-based products sold at over 16,000 retail locations in 22 countries. The company prides itself on its seed-to-shelf quality control, advanced packaging processes and sustainability practices.

With growing demand for its products, the company looked to improve the efficiency of its raw hemp seed processing operations, and the packaging of finished products for shipment to retailers. Hulled hemp seeds tend to clump and require gentle handling to avoid product degradation. Existing equipment was proving unsatisfactory. Plant space was limited, and dust needed to be contained to maintain plant hygiene.

“We were experiencing issues with operations,” says process engineer Eric Pilor. “We had been using a bucket conveyor to move hulled hemp seeds into the milling process, but it was not designed for handling seeds. As a result, we were losing nearly 20 lb (9 kg) of seeds every eight-hour shift.”

The company improved productivity, product quality, dust control, and overcame space constraints by installing flexible screw conveyors, BFC Bulk-Out bulk bag dischargers and Twin Centerpost bulk bag fillers, all from Flexicon Corporation, Bethlehem, Pa.

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Processing hemp seeds

Manitoba Harvest acquires hemp seeds from over 125 growers across Canada. The raw seeds arrive at the facility by truck and are stored in silos until ready for processing.

The seeds are conveyed to the processing area and into hulling machines which crack the outer shell. The company previously employed a vacuum conveyor to move the cracked seeds to two screeners that separate the hemp hearts from their outer shells, but replaced it with two flexible screw conveyor systems.

Each 30 ft (9 m) system consists of a 10 ft (3 m) long screw conveyor that connects to the charging adapter of a 20 ft (6 m) long screw conveyor.

Designed to gently move difficult-to-handle materials, each Bev-Con conveyor consists of a rugged, flat steel spiral with a beveled outer edge rotating within a rigid, food-grade polyethylene outer tube. The rotating screw self-centers within the tube, providing clearance between the screw edge and the tube wall, allowing the material to move forward without crushing or grinding.

“The conveyors are gentle on our product,” says Samuel Leung, process engineer. “No crushing occurs or turning the product into butter. We get a consistent product and, compared with previous methods, we get consistent feed rates. Previously we had issues with clumping and material slippage. All of that stopped when we installed our conveyors.”

The conveyors, as well as bulk bag dischargers and bulk bag fillers, are enclosed, protecting the plant environment from dust contamination.

Mobile flexible screw conveyors boost productivity

The screened hemp hearts proceed to packaging, or to further processing into hemp oil and hemp protein powder. Cold-pressing hemp hearts yields not only the oil, but protein-rich hemp meal that is milled and refined into protein powder.

To better manage the transition to downstream processing, Manitoba Harvest invested in two mobile flexible screw conveyor units with hoppers. Mounted on casters, these units move around the plant as needed to convey finished and semi-finished materials into bulk bags for the next processing step.

“The portable conveyors have made a big difference in our productivity and eliminated almost all of the waste,” says Pilor.

From processing to packaging

Finished hemp hearts enter the packaging area in bulk bags which are loaded into BFC bulk bag dischargers. Each discharger is configured with an electric hoist and trolley that ride on a cantilevered I-beam to lift bulk bags from the floor into the frame.

Pilor says the plant’s constrained space does not allow room for maneuvering a forklift. He adds that the BFC discharger’s hoist allows rapid and safe loading of bulk bags into the discharger without the use of a forklift.

Overcoming difficult-to-handle powders

In addition to hemp hearts, oil and protein powders, Manitoba Harvest manufactures a variety of hemp-based snacks and nutritional supplements. In support of these products, another BFC discharger and flexible screw conveyor combination feeds a blender that mixes protein powder and other ingredients. This discharger hoists bulk bags from the level below onto a mezzanine where the contents empty into a hopper from which a flexible screw conveyor feeds them into the blender. Since hemp protein powders are difficult to handle, the dischargers are equipped with Flow-Flexer bag activators that raise and lower the bottom edges of the bag into a steep “V” shape to totally empty the bag.

Hemp hearts require gentle bulk handling. (Colin Corneau photo)

Also improving flow from the bag and containing dust, the bag spout connects to a Spout-Lock clamp ring that allows a high-integrity, dust-free sealed connection between the clean side of the bag spout and the clean side of a Tele-Tube telescoping tube, which lowers, applying continual downward tension to aid flow from the bag.

“The dischargers have eliminated issues we had previously with material bridging and rat-holing,” Pilor says.

The blender gravity discharges into a Twin Centerpost bulk bag filler on the level below through a sealed chute. The filler is equipped with an inflatable connector to seal the bag inlet spout to prevent escape of dust, and a feed chute outlet port maintains dust-free air displacement during filling. The bulk bag fillers are totally sealed, eliminating contamination and dusting throughout the process.

Quality control and testing

Manitoba Harvest conducts over 30 safety and quality control processes in its operations, so before purchasing new equipment, the process engineers tested the flow of various hemp materials on full-size equipment at the supplier’s test lab. “That really helped a lot,” Pilor said.

All material contact surfaces of the new systems are constructed of 304 stainless steel and suitable for food-grade operations. Fully contained, the conveyors maintain ambient moisture and prevent against contamination.

“Obviously, quality is very important in the packaging process,” says Leung. “These systems have greatly reduced our manual processing efforts and we are virtually worry-free over dusting or the introduction of foreign objects into our material flow.”

“We’re a pioneer in the hemp processing business,” adds Pilor, “and our updated bulk handling system has helped maintain our leadership position.”

Flexicon Corporation / Manitoba Harvest

www.flexicon.com

www.manitobaharvest.com


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