More types of vacuum drying equipment, a wide range of applications, the relatively rapid development. This article will discuss several of the domestic and foreign development vacuum drying equipment dynamics described, in order to achieve the exchange of information and development of vacuum drying equipment to identify the problem to be solved to improve the level of vacuum drying equipment purposes. Keywords: vacuum drying; drying equipment; freeze drying vacuum drying has many advantages: a low pressure dry oxygen content is low, can prevent oxidative deterioration of the material being dried, can be dried explosive dangerous goods; can make the material at low temperatures moisture vaporization, easy drying heat sensitive materials; dried material can be recycled is valuable and useful content; dried material can be prevented from being toxic emissions of harmful substances, can become environmentally friendly types of "green" dry. Therefore, the application of vacuum drying equipment is widely used. The main disadvantage is the need for a vacuum drying steam vacuum pumping system capable of such high equipment investment costs, high operating costs; low equipment productivity, small yield. To overcome these shortcomings, many scientists made a lot of effort. Meanwhile, since the vacuum drying has many advantages, some products have to vacuum drying equipment. Therefore, the development of vacuum drying equipment will be very promising. 1. Continuous vacuum drying equipment at home and abroad unbalanced development in order to improve device yields, product quality assurance, ten years ago abroad to develop a variety of continuous vacuum drying equipment. But technical limitations in the domestic and awareness of the concept of subject, the relatively slow development. 1) belt type continuous vacuum drying equipment produced by the production of Japan's Osaka WL-VAQ-belt type continuous vacuum drying equipment, suitable for liquid material, muddy, paste sued concentration and a high viscosity boring and dry. Japan Okawa Production of original strain BV-100.5-type vacuum belt continuous drying apparatus, steam and conduction heating, the temperature of each section is adjustable, belt tensioners and speed adjustable. Swiss Bucher - Gade has developed a series of belt-type continuous vacuum drying equipment, with automatic cleaning device. Starting in 1995 in the belt type continuous vacuum drying equipment design, manufacture, installation and service, technology is more mature. Domestic belt type continuous vacuum drying equipment and rare, in 2004 in Guangdong Province Institute of Agricultural Sciences has successfully developed small-scale test equipment for drying banana flour with good results. 2) Grain continuous vacuum drying equipment grain drying is large, it must be continuous drying equipment. Former world have developed a lot of grain drying equipment, and vacuum dried grain is used in seed drying, vacuum drying because the cost is too high. In fact, this is a misunderstanding, according to Research and Design Institute Zhengzhou Grain Ho Cheung senior presentation, they developed a continuous corn vacuum drying equipment, production capacity of 60t / d, slightly higher than the hot air drying fixed investment, operating costs and hot air dried flat. If you consider the quality of the dried product, the drying process breakage, violence back rate, the total cost of vacuum drying at low temperature not higher than the hot air drying. 3) continuous vacuum freeze-drying equipment food rich in raw materials, a great need for a lyophilized product yield. Therefore, continuous food drying equipment appeared earlier. Danish ATLAS company in 1985 on the production of a CONRAD-800 type continuous freeze-drying equipment for the freeze-dried coffee production, production capacity of 13t per day, 2 is a schematic of the device. Figure 3 is a continuous production of the lyophilizer Germany. It made the first continuous vacuum freeze-drying equipment in 2000 successfully developed by the Shenyang Institute of Refrigeration Technology. Vacuum chamber using a rectangular structure with the spacer between the hopper and the drying out of the warehouse, within and out of the silo are equipped with automatic weighing system can determine the drying rate of freeze-dried food, the water and the final drying degrees. Two external water trap alternate work to achieve continuous capture water and melting ice. The gap between domestic and international sales of large continuous drying equipment. Danish ATLAS company from 1985 to 1990 and five years for the sale of 18 units of continuous drying equipment, including the purchase of Taiwan to Taiwan, and mainland provinces and cities has yet to introduce such a device, only one station has not yet been made equipment sales out. 2. Variety vacuum drying equipment at home and abroad are increasing for different purposes, we developed a variety of new different vacuum drying equipment. 1) The microwave vacuum drying equipment, energy saving, increase the drying rate. 2) spray freeze drying equipment combined spray and freeze-dried by the production of the material properties and product decisions, the material must be liquid slurry of particles after the formation of micro and nano-scale spray freeze drying rate increases, increase product Yield. 3) vacuum vapor drying equipment is specialized large-scale oil-immersed transformers and other electrical equipment similar apparatus for drying. Switzerland in the 1970s to develop this product. China in the 1980s, the introduction of such a device, after 90 years has been basically completed the introduction of digestion can now complete production. 4) small-scale experiment with drying equipment to meet the needs of schools and research institutes at home and abroad have developed several different functions lyophilized small experimental device. Figure 4-7 is one of several small-scale experiments in Germany with a freeze dryer Martinchrist company, its small size, light weight, multi-function. You can basically meet the lyophilized test a variety of materials. The country has Haimen Light Industrial Machinery Factory, and several other manufacturers began to digestion and absorption, the introduction of design, developed a new product, but the performance is not stable enough. Single-chamber system under sterile conditions, pre-freezing and drying are carried out in the condensation chamber. Dual-chamber system is carried out in the pre-freeze or spin-freezing temperature refrigerator vessel, dried in a drying chamber above was condensation chamber. 5) Separate lyophilized pharmaceutical use lyophilizer lyophilizer food freezing and drying are carried out separately, in order to achieve energy savings, save time, increase production purposes. Traditional medicine with lyophilizer were all frozen and dried in the machine once completed. Some companies in Western Europe and the United States, to achieve the same purpose with the freeze-dried food, the drugs previously frozen, and then into the dryer to dry. Figure 8 shows a continuous picture of drugs pre-freeze equipment. 3. Function vacuum drying equipment is increasing with the progress of electronics and computer technology, the control system of vacuum drying equipment and display functions generally increased. Zhengzhou Institute of Food Science developed corn vacuum drying equipment with automatic control and simulation screen display; Tofflon Shanghai, Beijing and other manufacturers of the original speed vacuum freeze-drying machine has a lyophilized determine the end point, the design freeze-drying curve, view the health status , storing multiple freeze-drying curve, print production information and other features. Foreign vacuum drying equipment function more, most have a robot in the drying process can be sampled for testing; some rotary type of vacuum drying equipment with a crushing and granulation functions; freeze-drying equipment for medical use could granulation. 4. Opinions on the development of vacuum drying equipment 1) vacuum drying equipment innovation is the fundamental way to slow the development of the current vacuum drying equipment, there is an important reason is that mutual imitation, hovering on the same technical level, the lack of innovation. The ability to imitate a strong, fast, innovative ideas difference, less investment. The focus on the competition to grab the market, Latin America, the price warfare. Better approach is in terms of quality and after-sales service, down some effort. But these are not a good way to develop the vacuum drying equipment, must invest human, material and financial resources to innovation. 2) Energy conservation is the key to development of vacuum drying equipment the energy shortage has received worldwide attention, the traditional concepts are considered high-energy vacuum drying equipment, because it needs to increase the vacuum pump. But have not seen the same kind of material, when dried to the same moisture content, the real energy contrast. Indeed, low temperature vacuum drying is dried in a closed space, a relatively small energy waste. Nevertheless, energy-saving vacuum drying equipment is still the key to development. Compared with other types of drying equipment, vacuum drying equipment, energy-saving focus should be on rational design, selection and use of vacuum systems. Can steam vacuum pumping system, not many, there are mainly two types, one is able to direct pumping steam pumps, main water jet pumps, steam jet pumps, water pumps and wet ring vacuum pumps; the other catching water is condensed way. These two approaches are high-energy, the former energy should be directed to improve the pumping efficiency of the pump; direction of the latter category is the design of energy-efficient as gas-solid phase change heat the structure and thermal efficiency. 3) continuous vacuum drying equipment is to improve the yield of products, an important method of energy conservation continuous vacuum drying equipment compared with the cycle vacuum drying equipment, auxiliary less time, saving time and improve production. At the same time he does not like cycle vacuum drying equipment, as each production cycle, the device temperature changes in the level once, resulting in part of the energy wasted in the repeated heating equipment components. Thus, saving energy. 4) vacuum drying equipment and other drying methods should be promoted composition is dried under vacuum production methods in combination with other drying methods can improve productivity and reduce product cost. For example, vegetables, aquatic products and fruits and other products, vacuum drying can ensure product quality, after vacuum drying if before cleaning blanching, dehydration by centrifugation, and then dried to remove the surface cold water, then into the vacuum drying equipment, on We can achieve significantly improve productivity while reducing production costs. Spray and freeze-dried combination is one of the combinations. This is similar to the combination, you can experiment to find very many, of course, you have to spend some time, energy and money. 

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