Wedge shaped hollow blades are densely arranged on the hollow shaft, and the hot medium flows through the hollow shaft. The heat transfer area per unit effective volume is very large. The temperature of hot medium ranges from - 40 ℃ to 320 ℃, which can be steam or liquid type, such as hot water, heat transfer oil, etc. Indirect conduction heating, without carrying air to take away heat, heat is used to heat materials. The heat loss is only the heat dissipation to the environment through the insulation layer. The heat transfer surface of wedge blade has self-cleaning function. The relative movement of material particles and the wedge-shaped surface produces a washing effect, which can wash off the attached materials on the wedge-shaped surface, and keep a clean heat-transfer surface during operation. The shell of the pulp dryer is Ω type, and two to four hollow mixing shafts are arranged in the shell. The shell has a sealed end cover and an upper cover to prevent the leakage of material dust.

The heat transfer medium flows through the shell jacket and the hollow mixing shaft through the rotary joint. The hollow mixing shaft has different internal structure according to the type of hot medium, so as to ensure better heat transfer effect.

1. The heat consumption of blade is low:

Due to adopting indirect heating method, there will not be large amount of heat energy being taken away, besides there is additionally heat-insulation outside of heating drum body, therefore for paste materials, it only consume 1.2 kgs of steam to evaporate 1.0 kg of moisture inside the raw material.

2. The cost of the blade dryer is low:

For unit effective volume, there is a vast heat-convection area, thus it will shortens the processing duration, and also facilitates to reduce equipment’s sizes, in the end the construction area and space is greatly decreased.

3. The range of material to be processed is wide:

It can apply different heating medium, thus it can not only process heat-sensitive material but also material to be processed under high temperature. The commonly applicable heat medium is as: steam, thermal oil, hot water, cooling water and etc. It can not only run continuously but also intermittently in many process fields.

4. The pollution is less:

There is much less dust material being carried or emitted out to environment. There is also much less material solvent being evaporated, which is easy to be processed. For processing conditions such as there is contaminated material or there is solvent to be recovered, the close-circuit circulation mechanism can be adopted.

5. The operation cost is low:

By adopting low-speed stirring mechanism and reasonable structure and less wear allowance, the maintenance cost is also very low.

6. Steady operation:

Due to the special compression-expansion stirring function of V-shaped blade, it makes it possible to get material granule contact with heat-transferring surfaces fully, thus within the axial inter-zones, the material temperature, humidity and mixing gradient is very small, which can guarantee process stability.