Comparison of paddle dryer and disc paddle dryer, the core equipment for sludge drying

Paddle dryer is a kind of low-speed stirring dryer with stirring paddles set inside the equipment, so that the wet material, under the stirring of paddles, can fully contact with the heat carrier and the hot surface, thus achieving the drying effect. The structure form of paddle dryer is generally horizontal, double-axis or four-axis. Because of its compact structure, high heat transfer efficiency, good self-cleaning performance, simple operation and control and other excellent performance, widely used in food, dyes, petrochemical, chemical, industrial sludge and other production areas. For paste, powder, slurry materials for simple heating or cooling, can complete the drying, cooling, heating, sterilisation, reaction, low temperature combustion and other unit operations.

Because the paddle dryer drying heat required to rely on heat conduction indirect heating, so the drying process does not need or only a small amount of gas to take away the moisture. It greatly reduces the part of heat loss which is taken away by gas flow, improves the heat utilisation rate, and is a kind of energy-saving drying equipment. Paddle dryer is widely used in petrochemical, chemical, metallurgy, food, medicine, pesticide and other industries in the powder, granular, cake, slurry drying materials.



The following is the comparison between dyeing leaf dryer and disc paddle dryer.

1 two paddle dryer in developed countries have been used for a long time, are more mature;

2 working principle is very similar, shell hollow jacket, hollow shaft and hollow blade (disc), is a pressure vessel, are indirectly heated drying equipment;

3 project implementation of the external access requirements are basically the same, just paddle dryer external size is slightly different, in the sludge drying project can replace each other;

4. Adaptability of viscous sludge. The paddle dryer's 栔-shaped paddle has a cutting effect on the sludge, so the equipment has a certain self-cleaning function for the sludge that is not sticky. But for the viscous sludge, because of the 栔-shaped paddle is not equal cross-section, can not use the sludge scraper, so it will lead to the drying surface adhering to the sludge, affecting the drying effect and the drying capacity of the equipment; disc paddle dryer discs have no cutting force on the sludge, but there are scraping knives, can be adapted to the highly viscous sludge, scraping knife maintenance or even replacement of the very convenient, low-cost;

5. Wear-resisting and safety. The sand content of sludge in China is about twice as much as that in developed countries, so the equipment selection should give full consideration to wear resistance. Paddle dryer's hollow paddle is a pressure vessel, internal pressure of 0.3 - 1.3MP, is the structural components of the equipment, due to the sludge has a cutting effect, after a period of time will inevitably lead to wear and tear, the occurrence of thermal oil or steam leakage (such as the use of thermal oil as a source of heat, which may lead to safety accidents!) As a pressure vessel, the disc of disc dryer is also a structural part, with 0.3-1.3MP pressure inside, the disc has no cutting force to the sludge, so it is not easy to be worn out, and the pushing and stirring of the sludge rely on the propeller stirrer on the edge of the disc (a small piece of steel plate, which is bolted to the edge of the disc, and is not a structural part), which is easy to be replaced and has low maintenance cost. It is easy to replace and low maintenance cost;

6 single equipment processing capacity mainly depends on the equipment heat exchange area, paddle dryer generally can only do 300M3 heat exchange area, equipment is difficult to large-scale; disc paddle dryer can do 400 ~ 500M3 heat exchange area, single equipment processing capacity is greater;

7 paddle dryer generally use double or four shafts, complex structure; disc paddle dryer is a single shaft, simple structure, failure rate and low maintenance costs;

8 paddle dryer running resistance, disc paddle dryer running resistance is small, disc paddle dryer unit heat exchange area of power consumption is about paddle dryer

The power consumption per unit heat exchange area of the disc paddle dryer is about 1/3~1/4 of the paddle dryer, and the power consumption is even lower, and the running cost is low;

Paddle dryer and disc dryer design principle is similar, are using indirect heat transfer on the material heating evaporation design, simple equipment, low energy consumption. Two kinds of equipment in the structure of a slight difference, the user can choose a more suitable one for their own material characteristics. Overall, for general conventional materials, the difference between the two is not obvious, are the industry's better choice.