Drying in industrial production
In the production, treatment and processing of solid matter, drying is often an essential process step. In many cases, drying requires a large amount of the energy consumed in the whole process chain, and takes up a lot of time and space.
This proves to be disadvantageous as drying is an inevitable part of the process for manufacturers and often means no rise in value. It is used, for example, to preserve products (durability, stability of food, sludge etc.) or to reduce weight (waste or building materials, sludge etc.). In some cases, the water within a material has to be extracted to prepare it for a following stage in the production process (e.g. automotive industry, plastics and textile industry, foodstuffs).
In the drying process, moisture is extracted from solid matter by evaporation. For this purpose, energy must be charged to the material.
This energy-input can be performed by:
- Convection – by means of a carrier gas, e.g. hot air, superheated steam or an inert gas
- Conduction – hot surfaces
- Radiation – microwaves, infrared, solar
Beside heat transfer, mass transfer also plays an essential role in drying. Usually, industrial drying processes combine various effects and methods in order to obtain a particularly suitable drying result for a specific product.
Guidelines for process design are deﬁned by the required quality of the product and its speciﬁc sensitivity. The incorporation of secondary engineering processes – such as preparatory and after-treatment of the product, materials-hoisting and conveying, ﬂow control, etc. – is essential for obtaining successful drying results.