A grain dryer is a piece of agricultural equipment that is used to dry grains, legume, grass and vegetable seeds and threshed clover crops after the harvesting process has taken place. Grain dryers are also used in the production of protein vitamin feed by drying products such as alfalfa, vetch, oats and green clover. The two types of grain dryers are shaft and rotary and they are either movable or stationary. They work by moving the products down a shaft by their own gravity and then drying them with a furnace powered by natural gas in most cases. This machine helps preserve and store products longer.