There are many types of vacuum drying equipment, a wide range of applications, and rapid development. This article only elaborates on the domestic and foreign development trends of several vacuum drying equipments in order to achieve the exchange of information, find out the problems to be solved in the development of vacuum drying equipment, and improve the level of vacuum drying equipment in China. Vacuum drying has many advantages: it has low oxygen content when it is dried under low pressure, can prevent oxidation and deterioration of the material to be dried, can dry flammable and explosive dangerous goods; it can vaporize the moisture in the material at low temperature, and it is easy to dry heat-sensitive materials; Recover valuable and useful ingredients from the dried material; prevent the release of toxic and hazardous substances from the dried material, which can be an environmentally friendly type of “green†drying. Therefore, vacuum drying equipment is increasingly used. The main disadvantage of vacuum drying is the need for a vacuum system capable of pumping steam, which results in high equipment investment costs, high operating costs, low equipment production efficiency, and low output. To overcome these shortcomings, many scientific and technological workers have made many efforts. At the same time, vacuum drying has many advantages. Some products have to use vacuum drying equipment. Therefore, the development of vacuum drying equipment will be promising. 1. Uneven development of continuous vacuum drying equipment at home and abroad In order to increase the output of equipment and ensure the quality of products, a variety of continuous vacuum drying equipments have been developed abroad more than ten years ago. However, due to the limitations of the technology level and people's perceptions, the development is slow. 1) Continuous vacuum drying equipment Japan Risen Production WL-VAQ type belt type continuous vacuum drying equipment, suitable for liquid materials, mud, paste, reported concentration and high viscosity boring drying. The BV-100.5 type vacuum belt type continuous drying device produced by Japan's Okawara Plant adopts steam and conduction heating. The temperature of each zone can be adjusted, and the tension and speed of the conveyor belt can be adjusted. The Swiss company Buch Gade developed a series of belt-type continuous vacuum drying machines with automatic cleaning devices. Since 1995, he has been engaged in the design, manufacture, installation, and service of belt continuous vacuum drying equipment. The technology is mature. Domestic belt-type continuous vacuum drying equipment is rare. In 2004, the Guangdong Academy of Agricultural Sciences successfully developed a small-scale test equipment for the drying of banana powder. 2) Grain continuous vacuum drying equipment The amount of dried grain is large and continuous drying equipment must be used. In the past, all countries in the world developed a lot of grain drying equipment. Vacuum dried grains are used in seed drying because vacuum drying costs are too high. In fact, this is a misunderstanding. According to He Xiang, senior engineer of Zhengzhou Institute of Grain Science and Design, the continuous corn vacuum drying equipment developed by them has a production capacity of 60t/d. The fixed investment is slightly higher than hot air drying, and the running cost and hot wind Dry and flat. If the quality of the dried product is taken into consideration, the breakage rate of the drying process, the waist rate, etc., the total cost of the vacuum drying at a low temperature is not higher than the hot air drying. 3) Continuous vacuum freeze-drying equipment Food raw materials are abundant, and the product that needs to be lyophilized is very large. Therefore, the continuous food freeze-drying equipment appeared earlier. Denmark's ATLAS company produced CONRADTM 800 continuous freeze-drying equipment in 1985 for freeze-dried coffee production, with a production capacity of 13 tons per day. Figure 2 is a schematic diagram of the equipment. Figure 3 is a continuous lyophilizer produced in Germany. The first domestic continuous vacuum freeze-drying equipment was successfully developed by Shenyang Refrigeration Technology Institute in 2000. The vacuum chamber adopts a rectangular structure. There is a spacer between the in-out silo and the drying chamber. The in-out silo is provided with an automatic weighing system, which can determine the drying rate, the amount of water output and the final drying degree of the freeze-dried food. Two external water traps work alternately to achieve continuous catching and melting. The sales of continuous freeze-drying equipment at home and abroad have a wide gap. Danish ATLAS Company sold 18 continuous freeze-drying equipments from 1985 to 1990, including one Taiwan in China. However, the mainland provinces and cities have not introduced such equipment yet. Only one domestically-made equipment has not been sold yet. Go out. 2. The variety of vacuum drying equipment at home and abroad are increasing For different purposes, various new types of vacuum drying equipment have been developed. 1) Microwave vacuum drying equipment saves energy and improves drying rate. 2) Spray freeze-drying equipment The combination of spraying and freeze drying is determined by the nature of the material and the output of the product. The material must be a liquid slurry. After being sprayed and frozen, micro-nano-scale particles are formed, which increases the drying rate and improves the product's Yield. 3) Vacuum vapor phase drying equipment is a device specially designed for drying large-scale oil-immersed transformers and other similar electrical equipment. Switzerland developed this product in the 1970s. China introduced such equipment in the 1980s. After the 1990s, it has basically completed its introduction and digestion. Now it can produce complete sets of equipment. 4) Freeze-drying equipment for small experiments In order to meet the needs of schools and research institutes, several small-scale experimental freeze-drying equipments with different functions have been developed at home and abroad. Figures 4~7 are several small experimental freeze dryers produced by German company Martinchrist. They are small in size, light in weight, and versatile. Basically can meet the freeze-dried experiment of various materials. Domestically, several manufacturers such as Haimen Light Industry Machinery Factory have begun to digest, absorb and introduce designs, and new products have been developed, but their performance is not yet stable. Single cavity system Under aseptic conditions, pre-freezing and drying are performed in the condensing chamber. Double cavity system The pre-freezing is performed in a low-temperature refrigerator or a rotary chiller, and the drying is performed in a dry room above the condensing chamber. 5) Freeze-dried separation medicine freeze-dryer The lyophilizers used in foods are frozen and dried separately to achieve the purpose of energy conservation, time savings, and production increase. The lyophilizer used in traditional medicine is frozen and dried in the machine at a time. Some companies in Western Europe and the United States, in order to achieve the same purpose as food lyophilization, pre-freeze drugs and then send them to a dryer for drying. Figure 8 shows a photograph of a continuous drug pre-freeze device. 3. The function of vacuum drying equipment is increasing With advances in electronics and computer technology, vacuum drying equipment has generally increased its control system and display capabilities. The vacuum drying equipment developed by Zhengzhou Academy of Grain Science has automatic control and simulation screen display functions. The vacuum freeze dryers manufactured by Shanghai Dongfulong and Beijing Speedway have freeze-dried end-point judgement, design the freeze-drying curve, and check the operation status. , storage of multiple freeze-dried curves, print production information and other functions. Vacuum drying equipment abroad has more functions. Most of them have robots and can be sampled and tested during the drying process. Some rotary type vacuum drying equipments have the function of crushing and granulation. Pharmaceutical freeze drying equipment can also be used for granulation. 4. Some views on the development of vacuum drying equipment 1) Innovation is the fundamental way to develop vacuum drying equipment At present, the development of vacuum drying equipment is slow. There are one important reason why they are imitations of each other. They are paralyzed at the same technical level and lack innovation. Imitation is strong, fast, poor in innovation, and low in investment. The focus of competition has been on robbing the market, pulling relations, and the price war. A better approach is to put some effort into quality and after-sales service. However, these are not good methods for the development of vacuum drying equipment. They must invest human, material and financial resources to innovate. 2) Energy Saving is Key to Developing Vacuum Drying Equipment The shortage of energy has attracted the attention of the whole world. The traditional concept thinks that the energy consumption of vacuum drying equipment is high, because it needs to add a vacuum pump. However, there was no real comparison of energy consumption when the same material was dried to the same moisture content. In fact, vacuum drying is drying at a low temperature in an enclosed space, and energy waste is relatively small. Despite this, the energy saving of vacuum drying equipment is still the key to development. Compared with other types of drying equipment, vacuum drying equipment should focus on energy saving This puts the rational design, selection and use of vacuum systems. There are not many vacuum systems capable of pumping steam. At present, there are two main categories. One is a pump capable of directly pumping water vapor. The main ones are water jet pumps, steam jet pumps, water ring pumps, and wet roots pumps; It is using condensation to catch water. Both of these methods consume relatively high energy. The direction of the former type of energy saving should be to increase the pumping efficiency of the pump; the latter type of energy saving is directed toward the design of the structure and thermal efficiency of the gas-solid phase changer. 3) Continuous vacuum drying equipment is an important way to increase product output and save energy The continuous vacuum drying equipment has less auxiliary time than the periodic vacuum drying equipment, which saves time and increases the output. At the same time, he does not need to change the temperature of the equipment once every cycle, as in the cyclical vacuum drying equipment, resulting in part of the energy wasted on repeated heating of the equipment components. Therefore, energy is saved. 4) Combination of vacuum drying equipment and other drying methods is a production method that should be promoted Vacuum drying combined with other drying methods can increase production efficiency and reduce product costs. For example, products such as vegetables, aquatic products, and fruits can be vacuum-dried to ensure product quality. If vacuum drying is followed by cleaning and blanching, centrifugal dewatering is followed by drying with a cold wind to remove surface water, and then sent to vacuum drying equipment. Can significantly improve production efficiency, while reducing production costs. The combination of spraying and freeze drying is also one of the combinations. This is similar The combination method can be found through experimentation, and it also takes a certain amount of time, energy and financial resources. 5. Conclusion Vacuum drying equipment is constantly innovating. There are still a lot of problems. If production, education, and research work closely together, the results will be even more pronounced. Two Hole Basin Faucet,Wash Basin Wall Mixer,Kitchen Wash Basin Mixer,Wall Mounted Washbasin Mixer Kaiping City Yibiao Sanitary Ware Co., Ltd. , https://www.faucetaoli.com