JOHN W. CARSON 1 Fundamentals

To avoid confusion in this chapter, I will use the term bin as a general descriptor of a bulk solids storage vessel of any size. 

In contrast to the cylinder section, a hopper has changing cross-sectional area over its height. In most cases the hopper is converging, so its cross-sectional area is smaller at the bottom than at the top. However, some hoppers used to store poorly flowing materials such as wood chips have a diverging geometry. 

Bins vary tremendously in size, from ones that store only a few kilograms of material to those with storage capacities in excess of 10 000 metric tonnes. The range of discharge rates can similarly vary from a few grams per minute to several thousand tonnes per hour. 

Bins are typically used to store incoming raw materials, intermediate products as part of the manufacturing process and/or outgoing products to be shipped to customers. The most common function of a bin is to provide surge capacity to compensate for effects of changes in production rate or frequency, and variations in rate or frequency of incoming or outgoing shipments. Another somewhat less common but still important function of a bin is to process, condition, age or blend the bulk solid stored therein. 

Bins can be very problematic, resulting in increased cost of plant operation, low product yield, extended time to market with new products, quality/product performance problems 

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