Hengyang Intelligent Control in the Application of a Rotary Dryer for Reduction in the Over-Drying of Cut Tobacco

It is well-known that rotary dryers are the main dehydration equipment used for many different types of processing such as food industry, agriculture, and tobacco production. The rotary dryers can remove water from the material through heat exchange; the greatest advantage of rotary dryers is that they can process more material in a more efficient way than other kinds of dryers.

At present, the application of automation control technology to the industrial rotary dryer is a highly effective way to improve operation, safety, and efficiency.

Cut Tobacco Rotary Dryer Principles of Operation

In its simplest form, the Rotary Dryer consists of a slightly inclined rotating cylinder, fitted with a series of peripheral flights arranged to lift, distribute and transport the material. The flights are designed to suit the particular handling characteristics of the material, which may vary with increasing dryness. The principle of operation is based on showering, or cascading the wet material through a hot gas stream, flowing either co-current or counter-current to the solids. The hot gas induces the evaporation of the moisture. The heat lost to the material and evaporation of water vapor reduces the gas temperature rapidly, such that it leaves the dryer at a comparatively low temperature. The efficiency of the dryer is largely dependent on the differential between the inlet and exhaust gas temperatures, although the heat transfer rate is also influenced by the relationship between the design of flights and the speed of rotation. However, irrespective of the gas and material temperatures the drying (or residence) time may be critical, as this is governed by the rate of diffusion of water from the core to the surface of the material. For special applications, the rotary cascade design is adapted to provide a shortfall, or ‘Cruciform’, lifter configuration.

Cut Tobacco Rotary Dryer Technical Details