Joel Dulin   |   October 24, 2019

Automating the Hemp Industry

Applying automation to hemp processing to save time and money.
Joel Dulin is the marketing manager for Biomass Engineering & Equipment, a material handling company which supplies in solutions for bulk, organic materials.

The hemp industry of 21st century North America is in its infancy. With it being such, change has come quickly and will continue to do so: more farmers are planting hemp as additional federal legislation gets passed and as more states in the United States implement hemp programs. Already, though, there are more crops than there are facilities to process them—California, for instance, may see more than seven billion dollars in crop rot this season—and the problem will for some time get worse until infrastructure catches up with the supply. As it does, automation technologies will be part of the solution.

Incorporating automation will not be without its challenges. Industry practices are inconsistent, and many jumped into the industry early with well-established methodologies before many automation technologies were available for hemp processing. Without the means, knowledge, or scale, many of these processors have relied on laborious practices from planting to harvest to bucking, drying, and transport. To make matters more difficult, processors have lacked the means to finance capital projects that incorporate automation technologies (an issue that should be resolved in the U.S. when the SAFE Banking Act has passed).

Overcoming these challenges is necessary for long-term growth and health of the industry. A key issue is the tight labor market. While a subculture around hemp and marijuana has helped provide a labor pool for small processing facilities, large-scale, industrial-sized processing plants with a corporate atmosphere won’t enjoy this luxury. And as hemp production normalizes, the uniqueness of working in the industry will wear off, eliminating a motivation for employees to sign on. Finding entry-level workers will eventually be as difficult in the hemp industry as in other manufacturing industries, as will replacing current workers when they move on.

Cost is another key issue. Increasing the scale of production will require processors to adopt automative practices to remain competitive. Labor is expensive, and automation, while costly upfront, will lower overall operational costs, which will allow companies to lower the price of their products and increase their margins.

There will always be a place for boutique-scale businesses, of course. But large-scale operations that produce high-quality, low-cost products will put pressure on small-scale processors. Lower prices and the advantages of higher margins will work against processors who lag behind technologically.

For small-scale, early processors, not only is the cost of automation an issue, but appreciation for and knowledge about automation varies widely. Many small-scale processors have a background in agriculture or have only recently begun farming; there is a gold-rush-type excitement around cannabis that has drawn people from a spectrum of backgrounds, many of whom lack knowledge of industrial practices. Those who do possess such knowledge will have an advantage, especially as they build large-scale production facilities.

A lack of knowledge can be disastrous for long-term growth and stability for those who do attempt to automate. Examples abound in other industries where this has occurred. Recent examples are available from the wood pellet industry. Demand for wood pellets for European power plants increased exponentially over the past two decades, and many pellet facilities have been built to meet the demand. In the rush, several have been built with sub-par conveyance systems, which performed so poorly that the mills failed; the pellet producers could never get production up to a profitable level due to downtime.

This is an example of what can go wrong when these systems are not understood and not prioritized. All equipment is not made equal. This is just true with conveyors as with more expensive processing machinery. I mention conveyors specifically because EPC firms, in general, tend to deprioritize material handling until late in their projects; conveyor systems tend to get what’s leftover of the budget. Inexperienced EPC firms are especially unlikely to understand the importance of material handling or the challenges involved in handling specific materials like biomass, bast fiber, and hurd. Cheap and poorly implemented conveyance systems result in expensive performance in the form of increased downtime and maintenance.

We suggest processors research equipment and inform EPC firms which systems they want before requesting quotes. There are no hemp industry experts yet—the industry is too new, and too much is changing, so EPC firms are as inexperienced as anyone in regard to equipment. Processors, therefore, need to talk to equipment manufacturers and other processors to find solutions that work well. Manufacturers who have experience with material similar to hemp, such as stringy barks, grasses, bagasse, and stover, are well worth contacting. Biomass Engineering & Equipment is one example.

By stating what equipment they want before requesting a quote, processors will ensure their quotes include the cost of quality equipment and that their EPC won’t go cheap on conveyors.

Conveyors

A few words regarding conveyors: Though not as eye-catching as the islands of production equipment, conveyors are, nevertheless, vital to an automated system. They are the arteries that enable automation to occur. Conveyors, along with chutes, metering devices, and storage with automated reclaim, are what make automation possible between processing machines.

When choosing conveyors, processors will first need to decide whether their operation or certain areas of their operation, call for agricultural or industrial/mill-grade equipment. Agricultural grade is essentially “light duty” and meant for temporary, seasonal use. Industrial- or mill-quality equipment is made for continuous, long-term use. If a processor uses agricultural equipment in an industrial setting, it will quickly wear out and require constant repair. Processors may get away with agricultural-grade conveyors that handle green biomass during harvest season, for example but need industrial-grade conveyors to handle dry material throughout the year. Throughput rates and operational hours will largely determine which system a processor needs.

As for which type of conveyance system producers will need, we suggest mechanical conveyors rather than pneumatic conveyance systems. Pneumatic systems are best used to convey dry powders. Material with inconsistent sizes such as biomass, hurd, and bast will not flow as well through these systems. Pneumatic systems also require much more energy to operate than mechanical conveyors, and they require filtering equipment, a baghouse, and a large amount of headroom to fit equipment. Because these systems produce emissions, processors may need to acquire an air permit to operate them, too.

The specific type of mechanical conveyor a processor uses will depend on the application. For applications that involve hurd and biomass (wet or dried), we suggest drag conveyors (also referred to as paddle conveyors, scraper conveyors, and chain conveyors). Drag conveyors require more maintenance than belt conveyors but are more efficient. More importantly, they eliminate virtually all carryback—material that sticks to the belt. With an average price of more than $60 per pound (2019), the cost of lost material due to carryback can be significant, especially when end product is considered. Even with primary and secondary scrapers, carryback is an issue with belt conveyors; no scraper system will eliminate 100 percent of carryback. Carryback is especially a concern with green biomass, which will stick to belts more readily than dry biomass.

Some will argue that the maintenance drag conveyors require outweighs their benefits. This, however, goes back to the issue of quality and the design of the individual conveyor. High-quality drag conveyors are available with designs that significantly decrease the amount of maintenance they require.

Drag conveyors may work for transferring bast and stalks, as well, but it depends on the length of the material. Whether drags or belt conveyors are used, processors should find a conveyor with a seamless tray, so material does not catch and form blockages.


Displayed is a layout concept developed by Biomass Engineering & Equipment for automating the receiving, storage, reclaim, and load out of bulk material at a manufacturing facility for natural animal bedding in southern Indiana.

Examples of Automation

At processing facilities, processors can use machines to feed, meter, and transfer material between processing islands. A well-functioning automation system will bring hemp from start to end product using conveyors and metering devices without humans touching it.

But there is much opportunity to automate the hemp industry besides conveyance equipment. It begins in the field. Small operations exist where plants are cut, collected, dried, and processed by hand. But industrial-scale operations also exist, which have applied modern agricultural practices and which automate much of this: planting occurs with tractors, harvesting with combines that buck the plant and pile the stalks and baling the stalks with balers.

Biomass Infeed and Storage

Processors have several options for automating their receiving process, all of which involve loading the biomass from the trailer directly into a metering device. Processors can receive biomass from moving-floor trailers into trailer receiving bins, which will meter the material into conveyors that lead to storage, grinders, or dryers. Or, they can receive biomass into a horizontal silo or bunker with moving floors, which, again, will meter the material to the next step in the process.

The biomass could be dumped onto the ground or a concrete slab. This is the cheapest option, but not the best. For one, it will result in a loss of material. With the price of hemp biomass what it is and considering potential loss of end product, the loss of biomass must be kept to a minimum. Two, dumping onto the ground results in contamination by dirt. Loss and contamination will be greater if the biomass is green. Storing on a concrete slab or on dirt will also require a worker to operate a front loader to feed the production line (unless the biomass is shoveled in).

Front-loaders can and should be avoided. They’re expensive to purchase and maintain, require an operator, and will contaminate biomass with rubber and dirt when they run over it. Also, when damage caused by the front loader is considered (these machines are unwieldy; damage will occur), the cost to operate them can be substantial.

A better choice for interim storage of green biomass during harvest and long-term storage of dry biomass is a silo with an active floor system, such as is found in horizontal silos or silos with negatively inclined walls. Processors should avoid storing biomass in traditional vertical silos due to the tendency of biomass to interlock and bridge. Green biomass can be especially problematic because of the stress it puts on the reclaim arm at the bottom of the silo. Processors who work with woody biomass commonly battle broken reclaim arms and bridged material in their silos. And when the arms break, the processors have difficulty repairing them, as they’re submerged in the material; they aren’t accessible from outside the silo. This problem is so common that some manufacturers working with woody biomass actually plan for their silos to fail and build expensive bypass systems for when this occurs.

Hemp processors need not experience this, however. They just need to install the right storage system.

Silos with negatively inclined walls and horizontal silos use different reclaim systems to address issues associated with vertical silos. Instead of reclaim arms, they use screws, push-pull steel strokers, or aluminum slats. Between strokers and slats, we prefer the former, as aluminum slats tend to wear out quickly due to the softness of the metal.

Due to the rate of growth the hemp industry is undergoing, processors will do well to purchase a modular storage system. With such a system, processors can add storage as needed and more easily change their layout without risking capital in a storage system that lacks the volume they need or which provides more storage than necessary. 

Bucking Green Plants

While equipment manufacturers haven’t yet developed a fully automated solution for bucking in a factory setting (as far as we’re aware), bucking by hand should become unnecessary with better harvesting equipment. Combines are available that separate seeds, stalks, and leaves. They’re expensive, and until recently not available in the U.S., so for some years, at least, bucking by hand will continue as standard practice.

As bucking is a major bottleneck and a laborious work, processes to autonomously buck hemp outside a combine need to be developed. Fortunately, bucking occurs during harvest, so processors do not face a year-round bottleneck with this process.

Drying

While hemp stalks are dried in the field, biomass is still often dried with laborious effort. After flowers and leaves cut, workers hang them in a dry location. This practice may continue just as tobacco farmers still hang tobacco to dry, though some farmers have begun using small dryers to get their biomass to market faster. Large dryers for use in co-ops or factory settings are available, which can receive great volumes of green biomass from storage or live infeed, too. For these, automated systems can meter and feed the biomass to the system.

Bale Infeed

Processors can also apply automation where they receive bales of hemp stalks. For round bales, workers can use bale splitters attached to the front of a tractor or skid-steer loader to split the bale into a hopper, which will meter the hemp on its way to the decorticator. For square bales, workers can use bale splitters or load them into an automated splitter machine. It should be noted that systems are available, which will split bales and feed the decorticator in one step.

Decortication

Currently, decorticators are fed by hand. To automate these machines, processors will need to meter their infeed and, if necessary, spread the stalks over the width of the infeed conveyor, which is possible with vibratory conveyors or other mechanical devices. Conveyors and reclaim paddles can easily accomplish metering. Screw conveyors should be avoided for hemp stalks, as the stalks will get hung up on the hanger bearings and may wrap around the flights.

Material coming out of the decorticator, if not directly bagged, can be fed via conveyors to dryers, bagging, or bulk storage.

As the industry matures, the need for automated systems such as these will become more apparent and commonplace. While fully automated systems may be years away, technology already exists to make it possible. From the field to the end product, human hands need not touch material, and employers need not worry about finding and replacing valuable laborers.

 

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