Features and applications of hollow paddle dryer

I. Structure principle: 
  The hollow paddle dryer is mainly composed of W-shaped shell with jacket and two hollow paddle shafts and transmission device. The shaft end is equipped with a rotary joint for hot medium introduction. 
  The heating medium is steam, hot water or thermal oil. The heating medium is passed into the jacket of the shell and two hollow paddle shafts to heat and dry the material by conduction heating, and the structure of the hollow paddle shafts is different for different materials. 
  The material is added by the feeding port, and the interface is renewed under the stirring action within the two hollow paddle shafts, while the material is pushed forward to the discharge port, and the dried material is discharged from the discharge port. 



Second, equipment features: 

  1 、Equipment is compact, covers an area of small. By the structure of the equipment can be seen, the heat required for drying is mainly by the dense arrangement of the hollow shaft on the wall of many hollow paddle to provide, and the jacket wall heat transfer only accounts for a small portion. Therefore, the heat transfer surface of the unit volume of equipment is large, which can save the footprint of the equipment and reduce the infrastructure investment. 
  2、High heat utilisation rate. The heat required for drying is not provided by hot gas, reducing the heat loss of hot gas away. Due to the compact structure of the equipment, and less auxiliary devices, heat loss is also reduced. Heat utilisation rate can reach 80%-90%. 
  3, wedge-shaped paddle with self-purifying ability, can improve the role of paddle heat transfer. The inclined surface of the rotating paddle and particles or powder layer of the joint movement generated by the dispersion force, so that the material attached to the heating ramp is easy to automatically remove, so that the paddle to maintain a highly efficient heat transfer function. In addition, as the two shaft paddles rotate in the reverse direction, the material on the slanting surface is compressed (when the two shaft paddle slanting surfaces are ^ close to each other) and expanded (when the two shaft paddle surfaces are ^ far away from each other) in alternate segments, so that the material near the heat transfer surface is intensely churned and the effect of heat transfer is improved. Wedge-type paddle stirring dryer heat transfer coefficient is high, 85-350W/(M2-K). 
  4、Less gas consumption, can reduce or save part of auxiliary equipment accordingly. As there is no need to use gas to heat, so it greatly reduces the amount of gas used in the drying process. The wedge paddle dryer only needs a small amount of gas to carry the evaporated moisture. The amount of gas is very small, only to meet the drying operating temperature conditions, the drying system does not condense dew. 
  Due to the small amount of gas, the dryer gas flow rate is low, the gas is taken out of the dust is less, after drying the system of gas dust recovery is convenient, you can reduce the size of the cyclone separator, eliminating or reducing the bag duster. Gas heater, blower, etc. can be reduced in size, saving equipment investment. 
  5、Wide adaptability of materials and even drying of products. The dryer is equipped with overflow weir, which can adjust the amount of material retention in the dryer according to the nature of material and drying conditions. It can make the material retention in the dryer reach 70%-80% of the cylinder volume and increase the residence time of the material to adapt to the drying requirements of difficult-to-dry materials and high moisture materials. In addition, it can also adjust the feeding speed, shaft rotation speed and heat carrier temperature, etc., and select the material residence time arbitrarily between a few minutes and a few hours. Therefore, it is suitable for both easy-to-dry and hard-to-dry materials. Wet content of only 0.1%, there have been examples of industrial applications. In addition, although there are many stirring paddles in the dryer, the material is mixed uniformly, but the material in the dryer from the feeding port to the outlet flow is basically a piston flow flow, residence time distribution is narrow, and the product is dried uniformly.   
  6、Applicable to a variety of drying operations. As mentioned before, wedge paddle drying can be adjusted through a variety of methods to drying process conditions, and its operation is easier to control than the operation of fluidised bed drying, air drying, so it is suitable for a variety of operations. 

  The main structure of the hollow paddle dryer is composed of a W-shaped trough and two rotating hollow shafts installed in the trough, on which hollow blades are arranged. The heat required for drying moisture is conducted to the material by the inner wall of the W-shaped trough with jacket and the wall of the hollow blades. During the drying process, the hollow shaft with hollow blades heats up the material and stirs the material at the same time, thus renewing the heating surface. It is a kind of continuous conduction heating dryer. 

Characteristics
  Compact structure, small floor space.
  High heat utilisation rate.
  The paddle has self-cleaning ability.
  The amount of gas is small, and some auxiliary equipments can be reduced or eliminated accordingly.
  Wide adaptability of materials and even drying of products.
  Suitable for a variety of drying operations.
  Scope of application:
  The machine is suitable for dealing with all kinds of paste, granular, powder and other thermally stable materials, under special conditions can also dry heat-sensitive materials and recovery of solvents in the drying process.

  Typical drying materials are: vinyl chloride, polyethylene, polypropylene, sodium chloride, iron oxide and so on.