The working principle is as follows: the drying of raw material is divided into two steps. First, raw material is dried with the mixing air of the tail air from the second dry and compensating hot air under positive pressure. The dried tail air is discharged to atmosphere. Second, the dried semi-finished product is carried to the second drying with fresh hot air under negative pressure. The finished product is measured and packaged. The used high temperature and low moisture tail air is used for the first grade drying. In this way the good circulating process is completed. The supplementary hot air may be adjusted freely. Therefore the machine has a wide application.
In the dryer, high-speed hot air stream sustain raw material in the suspending state, then the material is dried. Since air stream speed is very high, and material is suspending in air stream, the heat transfer surface between air and solid is large, heat transfer rate is high, and drying time is short(usually within several seconds). It’s specially suitable for drying heat sensitive materials.
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In drying process, clean cool air is heated by air heater, and mixed with wet starch sent by spiral feeder and material raiser. Wet starch is dried momentarily. Dry starch is discharged though centrifuge separator and star shape unloader . Exhaust air is let out into atmosphere.
Pneumatic coolers are a simple and reliable method of cooling and conveying dried product. In many instances ambient air will achieve the desired cooling duty. Where required, greater cooling capacity and a finer degree of control can be achieved with conditioned air at a controlled humidity and temperature.