Editor’s note: The following is an excerpt from an article that ran in the May 2017 issue of Dry Cargo International. For the full text, see page 56 of the online edition.
By Rebecca Long Pyper for Dome Technology
Temperature swings typical of springtime can set the stage for mold and mildew growth in grain storage, but selecting a reinforced concrete DomeSilo™ is a significant, proactive way to protect grains, even when stored for longer periods of time.
Grain producers know that mold, mildew and time are major concerns when storing large amounts of product during warm seasons. According to DTN/The Progressive Farmer, since grain stored improperly can experience quality issues as the weather warms up, farmers are encouraged to stay on top of management efforts like grain monitoring, coring bins, and equalizing air temperature in the bin by operating fans.
Although these are good housekeeping measures and no mechanized system can completely replace them, a reinforced-concrete DomeSilo provides a high level of self-management. “The environment is much more manageable than a traditional silo or convectional storage building. You do not have the daily drastic temperature fluctuations a traditional building has,” Dome Technology sales manager James Stoker said.
Protected, insulated storage
A more consistent environment is achieved thanks to science and innovative construction. The building process begins as the Dome Technology team inflates a PVC airform that provides the “form” for what will become the concrete shell; the airform will remain in place indefinitely to provide weatherproofing for the structure. With the airform inflated, polyurethane-foam insulation is applied to the inside to temporarily provide rigidity and to protect the concrete shell for the lifetime of the structure. Shotcrete is then applied, with rebar providing reinforcement.
With construction complete, a dome staves off some boundary issues steel bins and traditional silos face. First, the airform acts as an impermeable membrane that keeps moisture at bay. Second, the heat-sink properties of the reinforced concrete shell combined with the outer layer of polyurethane foam prevents extreme interior temperature fluctuation. These features reduce heating and cooling of the walls and air inside, minimizing or eliminating condensation that damages grain’s integrity.
Besides maintaining integrity, a major advantage of climate control is that businesses can safely store product until demand drives up prices. “Our solution reduces the risk of mold and mildew and allows grains to be stored for longer time periods,” Stoker said.
How much longer depends on the location, temperature and humidity. Maintaining proper moisture content is key for multiple reasons, including increased revenue. “The farmer wants the moisture content to be as high as possible because they can sell that weight. However, (grains) also need to be sufficiently dry to not decompose or have other issues,” said engineer for Dome Technology Adam Aagard.
To maintain an ideal interior environment, aeration systems maintain the moisture and temperature, making sure interior conditions will help achieve or preserve the appropriate long-term-storage moisture content.
“The systems we’ve used in the past are designed specifically for aerating and maintaining moisture in grain, and they can typically keep it within 1 to 2 percent of desired moisture content,” Aagard said.
Steel bins are not insulated and are thus prone to greater interior temperature swings, creating condensation problems. In contrast, the combination of a DomeSilo’s insulated concrete shell and an aeration system could preserve the life of grain at lower operational costs.
“Grain storage with proper aeration could increase the life of storage up to three years or more. With improper aeration, the life of grain could only last months if the grain contains high amounts of moisture,” Stoker said.