Engineering:Grain bin

Grain bins in southern Minnesota

Grain bins are bulk storage structures for dry corn, soybean, wheat, oats, barley and more. Grain bins are cylinders made of corrugated sheets or sheet metal with a coned metal roof that has vents. The floors of grain bins have aeration systems to keep good air flow through the commodities and keep it at a good temperature and humidity level to prevent spoilage. At the top of each grain bin there are tubed conveyors to transport the grain. The grain bin sits on top of a strong concrete base to help the structure withstand high winds and the massive weight from the grain.

Difference between grain bins and silos

Grain bins differ from farm silos which usually store foraged silage for animal feed and are made of concrete. Silos have no ventilation system promoting fermentation of the grain product. Silos typically have a domed roof with no conveyors.

Grain moisture levels

Corn is typically stored around 15% wet basis and soybean around 13%. The cold winter months are ideal for storing crops because of the low humidity levels, temperature, and pest problems. Storing grain in the bins for more than six months into the spring and summer means they will have to be aerated more then to keep the temperature and humidity down.

Grain dryers

Grain bins with dryer unit (center) putting out steam from drying the corn
(Click for video)

Grain bins typically have grain dryers next to them to heat the grain to remove moisture content from the grain before they are stored in the bins. Applying to much heat to the grain to get the moisture content down can cause shrinkage which cuts into profits. Some farms have small grain bins and a dryer to get the moisture content down before they sell to the larger local commercial grain bin.

Transporting to and from the grain bin

Grain bins at the railroad grain elevator site

When the grain is harvested from the farm with a Combine harvester the combine typically loads it into a grain cart, which then unloads it into a grain hopper trailer, gravity wagon, or dump truck to be hauled to the local grain bin. The commercial grain bin operator then sells the commodity at an opportune time and it is then transported, with a grain hopper trailer or dump truck, to a grain elevator to be put on a barge or grain train, if the grain bin isn't already at the grain elevator site.