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Industrial Hemp Dryers | Are Rotary Dryers Really Your Best Options?

Hang Drying Hemp
Hang Drying Hemp

In the world of hemp processing, drying hemp can be one of the most time-consuming components. There are many factors when choosing the right drying equipment for your specific application. There is no doubt a rotary dryer can be a great option for drying when putting together a hemp processing plant, but depending on what you are trying to achieve, they may not be your best option. In this article we will explore the different options for industrial hemp dryers and the pros and cons of each.

  • Types of Hemp Drying

  • Considerations for Equipment

  • Marion WaveMix for Hemp Products

Types of Hemp Drying


When you are looking for an industrial hemp dryer, you will likely run into more options than you care to take into consideration. Allow me to give you a simple break down of the most common types of hemp drying. There are three distinct ways in which hemp factories dry their product: indirect heating, direct heating, and hang drying (technically another form of indirect heating).

Hang drying is as simple as it sounds. The product is suspended from above in a climate-controlled facility with enough space between plants to allow ambient air to flow throughout the facility for drying the product. Hanging the cannabis plants in a temperature and humidity-controlled environment is a tried and true method that has stood up to the scrutiny of time. With small operations looking to keep capital expenditure low, hang drying can be a decent option. It is worth noting that hang drying cannabis can take upwards of two weeks, limits quality control, and scales poorly.

Indirect heating is a drying process in which heat generated by another source is applied to the product. Typically, this consists of heating air that is being pumped into a vessel and letting the air dry the hemp. Some classic examples of this indirect heating method are ovens, conveyor belts, rotary drums, and fluid beds. Using indirect heating to dry hemp product will save a lot of time in comparison to hang drying and can be used in continuous operations or batch operations depending on your specific needs. Using indirect heating to dry your hemp will typically have a lower capital cost than using direct heating methods. They will be more precise a drying method than hang drying, but less precise than direct heating. Industrial hemp dryers that use indirect heating methods are a great choice for someone looking to process more hemp than is practical with hang drying and can live with small inconsistencies in product.

Direct heating uses equipment like a microwave dryer to generate heat directly within the product resulting in an ‘inside out’ drying process rather than an ‘outside in’ drying process like you have with indirect heating. Microwave dryers are growing in popularity because of the precision that is often needed in the industrial hemp industry. Using a direct heating method like microwave dryer can be applied to continuous or batch operations. Microwave dryers for hemp products have tighter temperature controls, lower drying times, uniformity of moisture content, higher retention of CBD and Terpenes, and a greater degree of repeatability than other methods. They do however cost more than most indirect heating methods and can be limited on throughput in comparison to something like a continuous tunnel dryer.

Considerations for Equipment


Thermal processing equipment for hemp plants come in every shape and size. To be able to determine what pieces of equipment will best suit your application, you will need to know what questions to ask and what is the result you are looking for. The following are some things to take into consideration.

  • Drying Times – Does having a high temperature for fast drying times degrade your product beyond what is acceptable? What is the temperature range that is acceptable for your product and how long does it take to dry your product at that range?

  • Throughput – What are the throughput rates you are trying to achieve? Is maximizing throughput the number 1 goal for this application? Is there a minimum throughput that you must achieve and if the minimum is met, other factors are more important?

  • Consistency – How important is it to you that every batch come out exactly the same? How is the end product being used? Can you accept slightly different moisture content as long as the hemp is below a particular maximum moisture? Do you instead need processing equipment like a microwave dryer that can give you the same result without fail batch after batch?

  • Precision – Within a singular batch, how much control do you need over temperature control? Do you need heating to stop and start immediately or is it okay to have heating up and cooling down periods?

  • Footprint – How much space do you have for processing hemp? Are you okay with dedicating 2000 sq. ft of your facility to have space to hang dry 1 acre? Do you need something with low headroom? Is having an in-line process important? How much space do you need around the thermal equipment for safety?

  • Shutdown and Maintenance – Is down time for maintenance okay? Do you need spare parts on the shelf to avoid down time? How often does you equipment need to be cleaned? Are you having to clean in between batches?

Marion WaveMix for Hemp Products


Marion Process Solutions has developed a microwave dryer, a form of direct heating, specific for the hemp market. This hemp dryer has some distinct advantages over its competition such as: immediate start and stop control of heating, the ability to finely tune temperature ranges, more uniformity of the drying process, higher product integrity retention, high degree of repeatability.

In 2019, Marion had Analytical 360, a third-party testing company specializing hops and cannabis, put the Marion WaveMix through some rigorous trials. Some of the key takeaways from the testing were:

  • Reduction from 77% to 9% moister in 45 minutes

  • Reduction of THC content by 0.1%

  • Loss of CBD content of only 0.46%

  • Loss in Terpenes of only 1.52%

With Marion’s new hemp drying technology in the marketplace, customer can expect to get high CBD yield per pound of hemp, better Terpenes profile retention, tighter temperature controls, and uniformity of moister content post drying.

The Cannabis and Hemp markets may be still be in their infancy, but Marion is a thermal processing company with 80+ years of experience and plans to continue to innovate and stay at the forefront of emerging technologies.

The Tennant Specs team is excited to have a partnership with Marion Process Solutions and please to bring our many years of experience to this new market.

For more information regarding Marion WaveMix Cannabis, please visit:

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