Drying equipment technology has a wide service areas. Faced with a large number of industrial, physical and chemical properties of different materials, product quality and other requirements vary, drying equipment and technology is a cross-industry, cross-disciplinary, having the empirical nature of science technology. Typically, in the development and application of drying technology in three areas we need to have knowledge and skills. The first is the need to understand the use of the characteristics of the physical and chemical properties of the material to be dried and the product. The second is to be familiar with the principle of transfer of the project, namely the principle of energy transfer transfer, heat transfer, fluid mechanics and aerodynamics pass. It means third have implemented, namely the drying process can be engineered, major equipment, electrical instrumentation control and other aspects. Obviously, these three areas of knowledge and technology does not belong to a subject area. In practice, these three areas of knowledge and technology but also indispensable. So drying technology is a cross-sectoral, interdisciplinary technology. Although modern drying equipment and technology have developed a hundred years of history, but still within the scope of experimental science. Most of the technology is still a lack of drying equipment can accurately guide the practice of scientific theory and design methods. Practical applications, rely on the experience and small-scale test data to guide or major way. The reasons for this situation are the following: One reason is drying technology by relying on a number of basic disciplines (mainly transfer project is part of the scope of the subject) itself has the characteristics of experimental science. Example, aerodynamic research and development but also on "wind tunnel" test to drive, it means it is not out of the scope of experimental science. These basic subjects of their own level of development and decisions directly affect the level of development of drying technology. The second reason is that many drying process is a process conducted by a multi-disciplinary technical convergence, involves a wide range of variables and more complex mechanism. For example, in spray drying technology in the field, running track atomized droplets in the drying tower is the key to engineering design. The trajectory of the droplet with its own volume, mass, initial velocity and direction and the droplet and the hot air flow around other flow rates. However, these parameters as a result of mass transfer, heat transfer process, all the time changing. And the initial state, both the size distribution of the droplets of hot air can not be uniform. Obviously, for such a complex, changing process only with theoretical calculations for engineering it is unreliable. The third reason is the type of dry material is varied, its physical and chemical properties are also different from each. Different materials even under the same drying equipment conditions, mass transfer, heat transfer rate may also have a greater difference. If not treated differently, it may result in undesirable consequences. For example, some dried herbs, although both belong to a medicine just because there is a distinction medicinal origin or harvest drying conditions will have to change, otherwise the product quality will be substandard. Above three reasons determine the development and application of drying technology on a trial basis to. However, these features are often drying equipment technology intentionally or unintentionally overlooked. Due to the lack of test equipment manufacturer or type of failure (this is a common phenomenon in our country) should be done regularly to avoid drying experiment, and users lack of understanding of the characteristics of drying technology, and often give up the necessary test requirements. Its outcome is a device using ineffective, and even scrapped. In China, such examples are common, there had been a value of 20 million yuan of industrial drying equipment can not reach because of the requirements and the lessons to be idle. Therefore, the construction of industrial drying equipment, especially before larger device must be fully convincing test, and the test results as a basis for industrial plant construction. This is a significant characteristic drying applications. In addition, a wide range, each with a characteristic drying device also uses technology. Each technique has its own appropriate application fields. In engineering practice, to select the type of drying techniques applicable depending on the circumstances. This results in a significant impact on investment costs, operating costs, product quality, environmental requirements peers will. For example an enterprise, at once technically dried silica cake were selected over Van drying, spray drying, rotary air current fast drying modes. Eventually they realized that these three technologies have their own strengths. Van dried production of white carbon black although low productivity, the labor intensity; but good quality. And the rubber mixing products generated higher tensile strength values. Whirling airflow rapid drying compact equipment, low investment, high production efficiency, but the intensity of the generated index of rubber products is among the three worst. Spray drying production of white carbon black, product of the indicators in the middle among the three, but with good mobility products, small dust pollution, by the user and factory operators are welcome features. In the 1990s, a kind of drying method is more advanced problems silica used in the production, drying in our community who had caused controversy. In fact, the three devices have their own characteristics, the choice of what type of technology depends on the user's own conditions and product requirements. Which technology is more advanced conclusion does not exist. There are many similar examples, have shown a wide range of drying technologies, each with use features. So be careful comparison application, carefully chosen technical solutions, and by drying tests to assess technical solutions is also essential steps. 

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