Rotating cylinder is inclined slightly to the horizontal (high end is the feeding end, low end is the discharge end). Materials enter cylinder through feed chute and move forwards slowly. During this process, a series of peripheral flights mounted on the inner wall lift, distribute, transport the materials to promote better heat transfer. At the first stage, water is heated. Then moisture is reduced rapidly, because surface water is easily to get vaporized. Accordingly, temperature drops down quickly. Drying rate slows down at the third stage, because diffusion of water from core to surface gets harder and harder. Final products get discharged at the fourth section.

In drying process, some materials allow no contamination. Under such occasions, indirect rotary drum dryers should be your choice. Rotary cylinder is enclosed partially by an insulated jacket. A series of burners heat at the bottom of jacket. Under this way, heat transfer is by radiation and conduction via cylinder. Only a small air flow is required to take away the water vapor. The entrainment of fines is minimal, therefore a simple cyclone dust collector is enough for the de-dusting job.

Direct heated rotary drum dryers could be co-current or counter-current heating. Under different conditions, two types of heating have their own applications.

Advantages of co-current heating:
Materials meet with the hottest gas at the inlet of drum dryer. Heat transfer rate is rapid at initial stage, causing a quick and considerable drop in gas temperature. This prevents overheating of material and allows dryer cylinder to operate slightly cooler than counter-current configuration. It results in a longer service life and less maintenance of rotary dryer.

Advantages of counter-current heating:

• Drying rate is greatly governed by the speed of diffusion of water from the core to the surface. For materials that contain high internal moisture, the distance to the highest temperature gives enough time for water to migrate to the surface for evaporation.

• Suitable for materials that require extremely low level of moisture, where the last traces are of moisture are difficult to remove, or where an elevated product temperature is desired. As raw material of mortar, silica sand drying often adopt this technology, because mortar making process controls water content strictly.

Dajia-engineering take immense pleasure to introduce ourselves as one of the well established manufacturers and suppliers of Rotary Dryers. Our offered dryers are used for drying wet powders and various solid material, which are easily breakable and dispersible. These are equipped with a rotating drum along with an angle lifting blades which lift the feed as the drum rotates and showers it in the stream of hot air flowing through the drum.