Introduction to Grain Dryers

Grain dryers are generally categorized in three different ways:

as batch or continuous flow dryers,
as column or in-bin dryers, or
as cross-flow, concurrent flow, counter flow or mixed flow dryers.

Dryers can be operated at high temperatures using propane, natural gas or other fuels to heat the air. They can also use unheated ambient air or low temperature air that is heated up 5 to 10°F above ambient air temperature with electric resistance heater, gas burners, or solar heating [7].

Information on grain drying systems is available from numerous universities and other sources. A paper by Dr. Dirk Maier, Kansas State University, and Dr. Fred Bakker-Arkema (Michigan State University, retired) entitled “Grain Drying Systems” provides an overview of drying concepts and drying system considerations, and a brief discussion of the different dryer types and the advantages and limitations for each. Maier and Bakker-Arkema reported that realistic dryer capacities are only 70-80 percent of advertised values [8].

There is not an accepted industry standard for the rating of grain dryers in the U.S., so the ratings from Company A may not be comparable with those from Company B. Also, because of the conditions used for computer simulations or testing, the results may not be relevant to your location.. The energy efficiency of grain dryers is reported as energy in Btu per pound of water removed from the grain. Lower values show that less energy was used per pound of water removed from the grain; in other words, lower values indicate higher dryer efficiency [9].

The fact sheets that follow give detail about different dryer types.

> Continuous Flow Dryers

> Batch Dryers