Equipment Overview

　　The hollow paddle dryer can indirectly heat or cool paste, granule, powder and slurry materials, and can complete unit operation such as drying, cooling, heating, sterilization, reaction and low-temperature calcination. The special wedge-shaped stirring heat transfer blade in the equipment has high heat transfer efficiency and self-cleaning function of the heat transfer surface.

　　Wedge shaped hollow blades are densely arranged on the hollow shaft, and the thermal medium flows through the blades through the hollow shaft. The heat transfer area per unit effective volume is large, and the temperature of the thermal medium ranges from -40 ℃ to 320 ℃. It can be water vapor or liquid, such as hot water, heat transfer oil, etc. Indirect conduction heating does not carry air away heat, and the heat is used to heat the material. The heat loss is only the heat dissipation to the environment through the insulation layer of the body. The heat transfer surface of the wedge-shaped blade has self-cleaning function. The relative motion between material particles and the wedge surface produces a washing effect, which can wash away the attached materials on the wedge surface and maintain a clean heat transfer surface during operation. The shell of the paddle dryer is W-shaped, with two to four hollow mixing shafts generally arranged inside the shell. The shell has a sealed end cover and an upper cover to prevent the leakage of material dust and collect solvent vapors. A stopper is set at the discharge port to ensure the height of the material level, so that the heat transfer surface is covered by the material and fully functions. The heat transfer medium flows through the shell jacket and the hollow stirring shaft through a rotating joint. The hollow stirring shaft has different internal structures based on the type of heat medium to ensure heat transfer efficiency.

Equipment characteristics

1. The energy consumption of the pulp dryer is low: due to indirect heating, there is not a large amount of air to carry away the heat. The outer wall of the dryer is also equipped with an insulation layer, which only requires 1.2kg of water vapor to evaporate 1kg of water for the slurry material.

2. The cost of the blade dryer system is low: it has a huge heat transfer surface per unit of effective volume, which shortens the processing time and reduces the equipment size. This greatly reduces the building area and space.

3. Wide range of material processing: using different thermal media, it can handle both heat-sensitive materials and materials that require high-temperature treatment. Commonly used media include: steam, heat transfer oil, hot water, cooling water, etc. It can be operated continuously or intermittently and can be applied in many fields.

4. Low environmental pollution: Do not use carrying air, and there is little dust and material entrainment. The evaporation of material solvent is very small, which is convenient for treatment. For contaminated materials or working conditions that require solvent recovery, closed loop circulation can be used.

5. Low operating costs: The device operates normally, only 1 hour/day per person. Low speed stirring and reasonable structure. Low wear and tear, low maintenance costs.

6. Stable operation: Due to the special compression expansion stirring effect of the wedge-shaped blade, the material particles fully come into contact with the heat transfer surface. Within the axial range, the temperature, humidity, and mixing gradient of the material are very small, thus ensuring the stability of the process.

Field of use

　　Paddle dryers have been successfully used in fields such as food, chemical, petrochemical, dye, and industrial sludge. The characteristics of heat transfer, cooling and stirring of the equipment enable it to complete the following unit operation: calcination (low temperature), cooling, drying (solvent recovery), heating (melting), reaction and sterilization. The stirring blade is also a heat transfer surface, which increases the heat transfer area per unit effective volume and shortens the processing time. The heat transfer surface of the wedge-shaped blade also has self-cleaning function. The compression expansion mixing function ensures uniform mixing of materials. The material moves in a "piston flow" along the axial direction, and within the axial range, the temperature, humidity, and mixing gradient of the material are very small.

1. Using thermal oil as the thermal medium, the blade dryer can complete low-temperature calcination work. For example, calcium sulfate dihydrate (Ca ₂ SO4 • 2H ₂ O) is calcined and converted into calcium sulfate dihydrate (Ca ₂ SO4 • 1/2H ₂ O). Sodium bicarbonate (NaHCO Å) is converted into soda ash (Na ₂ CO Å) through calcination.

2. Cooling media such as water and cooling brine can be introduced for cooling. For example, the paddle type soda cooler used in the soda ash industry replaces the old air cooling soda cooler, saving energy and tail gas treatment equipment, reducing operating costs, and can also be used for cooling titanium dioxide, nickel iron alloy powder and various powdered materials. In a single machine, materials can be cooled from 1000 ℃ to less than 40 ℃.

3. Drying, the main function of the equipment, does not use hot air, making solvent recovery, energy consumption, and environmental control in an ideal state that is easy to handle. It is particularly suitable for solvents that need to be recycled and for flammable and easily oxidizing heat sensitive materials. It has been widely used in the fine chemical, petrochemical, and dye industries.

4. The uniformity of temperature, humidity, and mixing degree within the axial range allows the equipment to be used for heating or melting, or for some solid material reactions. It has been successfully used in the composite fertilizer and modified starch industries. Paddle dryers can be used to sterilize food and flour. The large heating area within the unit effective volume quickly heats the material to the sterilization temperature, avoiding long-term heating that can alter the quality of the material.

Adapt to materials

　　Petrochemical industry: polyolefin powder, polycarbonate resin, high and low density polyethylene, linear low-density polyethylene, polyacetal particles, nylon 6, nylon 66, Nylon 12, acetate fiber, polyphenylene sulfide, acrylic resin, engineering plastics, PVC, polyvinyl alcohol, polystyrene, polypropylene, polyester, polyformaldehyde, styrene acrylonitrile copolymerization, ethylene propylene copolymerization.

　　Environmental protection industry: PTA sludge, electroplating wastewater sludge, boiler ash, pharmaceutical factory waste, sugar factory waste, monosodium glutamate factory waste, and coal ash.

　　Chemical industry: soda ash, nitrogen phosphorus potassium compound fertilizer, kaolin, bentonite, white carbon black, carbon black, phosphogypsum, sodium fluoride oxide, calcium nitrate, magnesium carbonate, sodium cyanide, aluminum hydroxide, barium sulfate, calcium sulfate, calcium carbonate, dye, molecular sieve, saponin.

Technological process

  Feed - Drying - Condensation Recovery - Vacuum Pump - Discharge