Efficient energy utilization in drying operations
It is generally necessary to employ thermal methods of drying to reach what is termed a commercially dry condition. As a result, drying is an important part of most chemical and food processes and accounts for a significant proportion of total fuel consumption. The fluctuation of fuel costs over the past 10 years, together with the prevailing uncertainty of future availability, cost, and possible supply limitations highlights the continued need to actively conserve energy. This article discusses some of the factors affecting dryer efficiency and outlines certain techniques designed to reduce the cost of drying operations.
In appraising factors that affect dryer efficiency, it is useful to draw up a checklist of those items that have a significant bearing on both operation and economy. It is also appropriate -- prior to examining various options -- to emphasize that the primary concern is the cost-per-unit-weight of the dried product. This factor should govern any approach to dryer selection and operation. Additionally, it is increasingly necessary to evaluate the total energy requirements by considering the unit operation of drying in combination with other upstream processes, such as mechanical dewatering and preforming techniques.