Polyvinyl alcohol (PVA) drying
Vinyl acetate is polymerized to produce polyvinyl acetate, which can then be saponified to generate various forms of polyvinyl alcohol—such as flocculent, flake, granular, and powdered types—with alcohol solvency levels of 99.9% or 88%, depending on the amount of alkali used. Polyvinyl alcohol solutions exhibit excellent film-forming and emulsifying properties. It is widely used in industries such as synthetic fiber production, plastics, adhesives, coatings, construction materials, and more. Its applications span across the chemical industry, textiles, papermaking, leather tanning, and construction.
During the manufacturing process, the final polyvinyl alcohol precipitate obtained after saponification must be pressed and dried to form the final product. Due to its high viscosity and gel-like consistency, the evaporation rate of surface moisture is much faster than the internal moisture migration to the surface. This internal moisture movement becomes the limiting factor in drying speed. The heat required for this process is relatively low, but the drying process tends to be very slow. As a result, direct hot-air drying is generally not suitable for polyvinyl alcohol.
Currently, most manufacturers use vacuum rake dryers for this purpose. However, these dryers only have jacket heating surfaces, and the material does not fully fill the cylinder, resulting in only about 60% of the jacket area being effectively utilized. This leads to large equipment sizes, increased space requirements, and higher civil engineering costs. Additionally, the material movement within the vacuum rake dryer often fails to maintain a strict first-in, first-out flow, creating dead zones and stagnant areas that may lead to overheating, degradation, and discoloration of the retained material.
Hollow blade dryers represent an improved version of vacuum rake dryers. While vacuum rake dryers can handle a wide range of materials, most hollow blade dryers are also capable of processing similar materials. The key improvements include:
1. Transitioning from batch to continuous operation.
2. Enhancing heat transfer efficiency and reducing equipment size.
3. Ensuring full contact between the heat transfer surface and the material for more uniform heating, shorter processing times, and less thermal degradation.
4. Changing the material flow path to a microscopic spiral forward and macroscopic piston flow.
5. Making the equipment easier to clean when switching between different materials.
Thanks to these advantages, Sanmenxia Pakide Drying Engineering Co., Ltd. was able to win the bid for a polyvinyl alcohol manufacturer in Shanxi Province. They provided a large-scale hollow blade dryer tailored for the efficient drying of polyvinyl alcohol, meeting the specific needs of the production process while improving overall performance and safety.
Ceramic And Alumina Ball ,Alumina Ball,Alumina Grinding Ball,Alumina Ceramic Ball
Ningbo Cijie Chemical Equipment Co., Ltd. , https://www.chemicaltower.com