Grain storage systems design

As agriculture has grown in scale and farmers learned to produce crops in quantities larger than the amounts needed for their immediate use, the need for methods to store and transport large quantities of grain developed. Because agricultural grains are biological materials that interact with their immediate environment they must be stored, transported, and conveyed using methods that preserve their quality as seeds, food stuffs, or raw materials. Proper management throughout the harvesting, cleaning, drying, conveying, and storage processes maintains grain in its proper state for use. Grain is often harvested at a moisture content that is too high for safe storage. Drying is the most common post-harvest process performed for the long-term preservation of grain. Grain quality is significantly affected by the drying process and type of dryer. Various numerical models have been developed to simulate the drying process of agricultural grains based on either heat and mass balances or systems of differential equations. Grain is stored in round bins, piles, and flat storage structures. Like all structures, grain bins and buildings storing agricultural grains are designed to resist various combinations of loads without exceeding the appropriate limit states of the materials of construction. Storage facilities for agricultural grains are designed based on the assumption that grain is a free flowing material and the analysis of their physical behavior overlaps with many aspects of soil mechanics. Numerous design codes exist which can be used to estimate the loads exerted by grain on bins. These loads are a function not only of the conditions of the grain being stored but also the type of storage that is being used. In almost all grain facilities grain must be moved throughout the facility from one operation to another. A key design element of any grain handling system is to specify the desired processing rate between delivery and receiving stations. Grain handling can be done by chutes, screw conveyors, belt conveyors, and pneumatic conveyors. Each of which have their own design criteria. To maintain grain quality grain is often cleaned as well using many different processes. To understand more the behavior of grains the properties of grains and grain in bulk are often tested. There are many testers for measuring flow properties of particulate systems. Most of these testers are adaptations of direct shear test devices used in soil mechanics by civil engineers. The major difference is that the size of the grain particles presents unique test conditions much different than soils. Modeling of grain and grain in bulk is done using both analytical and computational techniques. These analytical and computer models are much different than the empirical techniques which have been used over the last 100 years to design bins.