Sugar beet pulp, a by-product of extracting sugar from sugar beets, has been receiving growing attention in agriculture as of late for its value as an alternative to corn silage and because of the many benefits it can offer to livestock producers. And as the sugar beet market grows, livestock producers can look forward to a growing supply of the material.
While sugar beet pulp may be used directly from the extraction process in wet form, drying the product increases its usability and provides a few advantages along the way. As such, the rotary dryer is gaining a more critical role in the industry, preparing a higher-quality animal feed product, and allowing for more widespread use.
Sugar Beet Pulp as an Animal Feed
With several market circumstances driving demand, industry forecasters anticipate that the sugar beet market will witness a CAGR of 6.2% between 2019 and 2025.
Sugar beet pulp is recognized for its high amount of digestible fiber and its energy density (sugar beets offer a greater energy value than corn silage¹). As such, producers are turning to the pulp as a way to increase fiber in animal diets without sacrificing energy density, making the by-product an attractive option for finishing diets, which aim to quickly add meat in preparation of sale.
Among other benefits, sugar beet pulp has also been shown to improve ruminant digestibility of low-quality forage diets such as straw, by increasing the number and variety of fiber-digesting bacteria in the rumen.¹
In addition to being an excellent replacement for corn silage, sugar beet pulp is considered a high-quality forage and can help to extend on-farm forage supplies, which is particularly beneficial during times of challenging weather conditions such as drought.
The pulp is widely used in feeding beef cattle, gestating or lactating cows, horses, and more recently, sheep. It is even used in the production of some pet food, where it cleanses the lower digestive tract and hardens stools.
Why a Rotary Dryer is Necessary for Sugar Beets
Sugar beet pulp consists of the solids left over after sugar has been extracted from the harvested sugar beets; washed sugar beets are sliced into thin strips called “cossettes” and mixed with hot water in order to extract sugar via diffusion.
The extracted sugar solution moves on, leaving the wet cossettes, now termed “wet pulp.” The wet pulp product typically has a dry matter content of around 6-12%. This wet pulp can be sold to livestock producers as-is, or as is often the case, sent to presses to reduce the high moisture content and produce a “pressed pulp” with a dry matter content between 18-30%.¹
While wet or pressed pulp can be used as-is, further drying offers several benefits. For the following reasons, many producers opt to incorporate a rotary dryer into their operations:
Improved Handling
The high moisture content of wet and pressed pulp makes handling especially difficult. By drying the product, handling characteristics are greatly improved.
Reduced Transportation Costs & Increased Distance of Transport
As with any moisture-laden material, transportation quickly becomes expensive and less economically feasible at greater distances. With a moisture content of around 95%, sugar beet pulp (unpressed) is significantly limited in how far it can be transported. Even pressed pulp, with a slightly lower moisture content, is limited in transportation potential.
Drying the product down to roughly 10% moisture significantly reduces transportation costs and allows the product to be economically transported significantly further from its origin; dried sugar beet pulp typically has a dry matter content between 87-92%, making it much more economically attractive to transport.¹
Storage
As with other high-moisture materials, storage of wet or pressed pulp is also limited.
Drying sugar beet pulp minimizes the potential for growth of undesirable bacteria, such as Lactobacillus, which is commonly encountered with pressed pulp storage. Storage of pressed pulp has also shown to produce a “greasy” silage, depending on material and storage conditions. This greasy product is less palatable to livestock and can also further complicate handling. By contrast, the use of a sugar beet pulp dryer produces a stable product that can be stored for up to one year.²
Preparation for Pelleting
Sugar beet pulp is commonly pelleted to further improve handling and transportation qualities. Drying helps to facilitate the pelleting process by producing a stable feedstock within the precise range of moisture necessary for adequate pelleting. If beet pulp moisture was too high, the downstream granulators would become clogged; too low and the resulting pellets could be too fragile.
Sugar Beet Rotary Dryer Operation
The rotary drum dryer is one of the most commonly selected types of industrial dryer for processing sugar beet pulp, as it accommodates a high throughput and is more tolerant of variation in feedstock moisture.
Prior to drying, the wet cossettes are pressed to remove as much moisture as possible, in order to reduce the burden on the dryer. Pressed pulp is then fed into the rotating drum, where it is picked up by flights or material lifters, which cascade the material through the hot air as the drum rotates.
The drum is of the direct configuration, meaning the products of combustion and the beet pulp are in direct contact with each other to maximize heat transfer.
The tumbling action promotes even heat distribution and drying throughout the material bed. In many cases, the dryer drum shell is sectioned into quarters for a more gentle drying of the material.
Conclusion
The growing sugar beet market will yield an expanding stream of beet pulp. Fortunately, this process by-product holds significant value as an animal feed product, providing an alternative to corn silage, serving as a high-quality forage, and even potentially offering some digestive benefits as well. Through drying, sugar beet pulp that is otherwise limited in transportation and storage, is extended in value and usability, because it is converted to a storable, stable animal feed product ideal for pelleting.
FEECO is the industry leader in rotary drum dryers for everything from chemicals to manure. Our extensive experience allows us to customize our dryers for the specific challenges of their intended application, providing an optimized drying solution. Dryer testing is also available through the FEECO Innovation Center, where drying processes are developed and refined every day. For more information on our beet pulp dryers, or dryer testing, contact us today!