In the earliest days of drying, in order to conveniently store food, the method of drying the food naturally, after the change of people began to use the fire to dry, and then people began to use machinery and equipment to dry, this has a real meaning. Drying equipment on.
In the production and life of human beings, it is often the case that it is necessary to remove a certain object from moisture. Such objects may be solid or liquid or gaseous. In most cases, the moisture content of an object is moisture, and sometimes it is other components such as inorganic acids, organic solvents, and the like. This process of removing moisture from an object is referred to as "dewetting." The method of dehumidification is divided into several categories according to the working principle, and drying is one of them.
Usually, the process of dehumidification by thermophysical methods is called "drying". The utility model is characterized in that the phase change process such as volatilization, condensation and sublimation of the moisture in the material is separated from the object by heating, cooling, decompression or other energy transfer to achieve the purpose of dehumidification. Dehumidification methods that do not have this feature are generally not included in the scope of drying technology.
Some dehumidification means, such as liquid is heated and concentrated, although it also has the characteristics of thermophysical dehumidification, but it is customary not to think that enrichment is a drying technique. With the development of the times, people have gradually incorporated some new dehumidification technologies that are not thermophysical methods into the field of drying technology, such as molecular sieves and supercritical fluid extraction. Therefore, the definition and scope of drying technology is a customary concept that is constantly expanding.
Equipment used for drying operations. There are many types. According to the operating pressure, it can be divided into normal pressure and reduced pressure (a vacuum dryer is also called a vacuum dryer). According to the operation method, it can be divided into batch type and continuous type. According to the drying medium, it can be divided into air, flue gas or other drying medium. According to the movement (material movement and drying medium flow), it can be divided into cocurrent, countercurrent and crossflow.
The drying technologies commonly used in traditional industrial production mainly include: van drying, tunnel drying, drum drying, drum drying, solar drying, microwave and high frequency drying, infrared thermal radiation drying, and the like. In addition, in various industries, such as grains, fruits and vegetables, wood, tea, dairy products, Chinese herbal medicines and other industries, there are also proprietary drying technologies suitable for their own characteristics. These traditional drying technologies have a long history, mature and reliable, and have been obtained in the world and in China. A wide range of applications.
Petroleum and chemical industries: polymerization, condensation, distillation, melting, dehydration, forced insulation.
Oil industry: fatty acid distillation, oil decomposition, concentration, esterification, vacuum deodorization.
Synthetic fiber industry: polymerization, melting, spinning, stretching, drying.
Textile printing and dyeing work: heat setting, drying, heat capacity dyeing. Non-woven industry: non-woven fabrics. Microwave medicinal sterilization drying equipment
Feed industry: drying.
Plastics and rubber industry: hot pressing, calendering, extrusion, vulcanization molding.
Paper industry: drying, corrugated paper processing.
Wood industry: plywood, fiberboard compression molding, wood drying.
Building materials work: gypsum board drying, asphalt heating, concrete component maintenance.
Machinery industry: painting, printing and drying.
Food industry: baking, heating.
Air-conditioning industry: industrial plants and civil buildings for heating.
Microwave vacuum drying equipment
Road construction industry: asphalt melting and heat preservation.
Pharmaceutical industry: drying.
Light industry: production of ink, washing powder.
In recent years, a number of new drying technologies have emerged internationally. Representatives include: pulse combustion drying, collision flow drying, impact through drying, sonic field drying, supercritical fluid drying, superheated steam drying, contact adsorption drying, etc. These new technologies have a certain mechanism compared to conventional drying techniques. Breakthrough, but still need to be perfected in industrial application. These new drying technologies in China are still in the stage of preliminary research.
The meaning and use of drying technology
2018 12/25
