The fluid bed dryer with internal heat exchanger is specially suited for non-abrasive temperature sensitive fine powder product like plastics. Heat transfer units (tube or plate type) are built inside the equipment. About 60% - 80% of the heat capacity necessary for drying is supplied from the units. Consequently, the quantity of hot air can be decreased, the equipment becomes compact and auxiliary equipment is also miniaturized.

The distributor plate is fixed at the bottom of a rectangular vessel (e.g. under case). Hot air is passed through the distributor plate; wet material is fed into the dryer continuously by a screw feeder or rotary valve at constant rate. The air velocity can be varied as desired. After lapse of designed residence time, the dried product is continuously discharged at the overflow and underflow outlets. The exhaust air is vented out after processing through a dust separation system.

As wet material fed to the first drying chamber is mixed and dispersed into the residence material, the material with comparatively high moisture content can be also dried. At and after a second drying chamber piston, flow ability can be obtained by adjusting the numbers of the partition plates according to the required residence period. The adoption of the discharging method by an overflow gate ensures the easy control of residence period. The perforated plate with the fixed direction ensures easy discharging. Due to few destruction of particle, suitable for drying granular or crystallized material.