Starch Air-Flow Dryer

Engineering Overview of Starch Air-Flow Dryers

Starch is a polymer of glucose; when hydrolyzed to the disaccharide stage, it becomes maltose, and upon complete hydrolysis, it yields a monosaccharide (glucose). Starch is classified into two types: amylose and amylopectin. The former has an unbranched helical structure; the latter consists of 24 to 30 glucose residues linked end-to-end by α-1,4-glycosidic bonds, with α-1,6-glycosidic bonds at the branch points. Amylose turns blue when exposed to iodine, while amylopectin turns purplish-red. This is not due to a chemical reaction between the starch and iodine, but rather because the central cavity of the starch helix can precisely accommodate an iodine molecule. Through van der Waals forces, the two form a blue-black complex. Experiments have shown that individual iodine molecules cannot turn starch blue; in fact, it is the iodine ion (I3) that causes the blue coloration. Starch is a nutrient stored in plants, found in seeds and tubers, and is present in high concentrations in various plant species.

Principle of the Starch Airflow Dryer

This is a high-capacity drying device that employs the principle of flash drying. It utilizes the rapid movement of heated air to carry the wet material, suspending it in the hot air stream. This intensifies the entire drying process and increases the rates of heat and mass transfer. Materials dried via this airflow method have nearly all their free moisture removed (for example, materials such as starch with an initial moisture content of ≤40% the final product moisture content can be as low as 13.5%). Furthermore, the dried material does not undergo any deterioration, and production capacity is significantly higher than that of conventional dryers, allowing users to achieve substantial economic benefits in a short period.

Applications of Airflow Dryers

Suitable for drying and dehumidifying powdered materials in industries such as pharmaceuticals, chemicals, food, building materials, and plastics. Examples include starch, fish meal, table salt, distillers' grains, feed, gluten, plastic resins, mineral powder, pulverized coal, chlorosuccinic acid, A·S·C benzoic acid, 2·3· acid, polyvinyl acetate, sodium sulfate, and sodium metabisulfite.