Many types of vacuum drying equipment have a wide range of applications and rapid development. In this document, there are only a few domestic and international developments of vacuum drying equipment, in order to achieve information exchange, to determine the problem of the development of vacuum drying equipment to be solved, and to improve the level of my vacuum drying machine.
Key words: vacuum drying; drying equipment; freeze drying
There are many advantages to vacuum drying: when the drying voltage is low, the oxygen content can be dried to prevent oxidation and deterioration; the material can be flammable and explosive; the material can be evaporated at low temperature, and the heat can be easily dried Sensitive materials; can recover valuable and useful components of dried materials; can be environmentally friendly type of "green" drying to prevent the discharge of toxic and harmful substances from dried materials.
Therefore, the application of vacuum drying equipment is increasing. The main disadvantage of vacuum drying is that a vacuum system for pumping water vapor is required, which makes the cost of equipment investment high, and the operating cost is high; the equipment has low productivity and small output. In order to overcome these shortcomings, some skilled workers, many efforts.
At the same time, there are many advantages to vacuum drying, and there are vacuum drying equipment for some products. Therefore, the development of vacuum drying equipment will be promising.
Unbalanced development of vacuum dryers at home and abroad
In order to improve production equipment and ensure product quality, various foreign continuous vacuum drying equipment were developed more than 10 years ago. However, the technical level in China and the people's understanding of the concept constraints, the development is relatively slow.
1) Continuous vacuum dryer
Hisaka wafer-level VAQ belt-type continuous vacuum drying equipment produced in Japan is suitable for liquid materials, muddy, creamy paste viscosity and high concentration sued dry boring.
Daheyuan Japanese-style production line company, 100.5 vacuum belt drying equipment, using steam and conduction heating, adjustable temperature part, adjustable tension of conveyor belt speed. Switzerland Buch-Gade has developed a series of belt continuous vacuum drying equipment with automatic cleaning device.
Engaged in the design, manufacture, installation and service of vacuum belt drying equipment since 1995, more mature technology.
Equipment with continuous vacuum drying is rare. In 2004, Agricultural Science Institute, Guangdong Province has successfully developed a small-scale test equipment for dried banana powder, which is very good.
2) Grain continuous vacuum drying equipment
A large amount of grain drying requires continuous drying equipment. A large number of grain drying equipment have been developed in all countries in the world, and they use vacuum drying to dry grain seeds because of the high cost of vacuum drying.
In fact, this is a misunderstanding, according to the Grain Science Research and Design Institute, Zhengzhou, He Xiang, senior engineer, the continuous development of corn vacuum drying equipment, the production capacity is 60 tons / day, slightly higher than the fixed asset investment of hot air drying, Operating costs are on par with hot air drying. If you consider the quality of the dried product, the breakage rate during the drying process, the rate of violence, such as the waist, the total cost of the low-temperature vacuum drying state should not be less than that of the high-heat air drying.
3) Continuous vacuum freeze drying equipment
Food is rich in raw materials, requiring large quantities of freeze-dried products.
Therefore, freeze drying equipment was used for food earlier. In 1985, Atlas Company produced the Ju-800 continuous freeze-drying equipment in Denmark to produce freeze-dried coffee, with a daily production capacity of 13 tons. Figure 2 is a schematic diagram of the equipment. Figure 3 is a continuous freeze dryer produced in Germany.
The first continuous vacuum freeze-drying equipment was developed in 2000 by Shenyang Refrigeration Technology Research Institute. The vacuum chamber with a rectangular structure, the isolation film between the in-out warehouse and the drying hopper, and the launching silo are all equipped with an automatic weighing system, which can determine the drying speed, water and degree of final drying of freeze-dried food. Two external devices work and catch water to achieve continuous ice melt and fisheries.
The gap between domestic and foreign sales of continuous freeze drying equipment. From 1985 to 1990, Atlas Denmark sold 18 continuous freeze-drying equipment in 5 years and purchased 1 unit. The inland provinces and cities have not introduced this equipment, and only 1 domestic equipment has not been sold.
There are more and more varieties of vacuum dryers at home and abroad
For different purposes, different development of new types of vacuum drying equipment.
1) Energy-saving microwave vacuum drying equipment to improve drying speed.
2) Spraying equipment, spray freeze-drying and freeze-drying are a combination of properties, materials and products, production decisions, and the required material liquid slurry, formed by freezing spray micro-nano-sized particles, increasing the drying rate and improving product yield .
3) Steam vacuum drying equipment is designed for similar drying of large oil-immersed transformers and other electrical equipment. Switzerland formulated the product in the 1970s in the 20th century. China introduced this kind of equipment in the 1980s, and basically completed the introduction and digestion in the 1990s, and the production can now be completed.
4) Small-scale experiments use freeze-drying equipment, for schools and research institutions to meet the needs, some small-scale experimental equipment for freeze-drying with different characteristics has been established at home and abroad. Figures 4 to 7 are several small experiments of the freeze dryer Martinchrist produced by the German company, which is small in size, light in weight and multifunctional. Has been able to meet a variety of experimental materials, freeze-dried.
Home has four Haimen Light Industry Machinery Factory and some other manufacturers began to absorb, introduce, design, develop new products, not only performance and stability.
single chamber system
Under sterile conditions, freezing and drying are carried out in the coagulation chamber.
Dual chamber system
Pre-freeze cryogenic spin freeze in the freezer or in a browser, and dry indoors in a condensation drying chamber on top.
5) Separation of traditional Chinese medicine for freeze-drying with freeze-drying machine type
Food freezing and freeze-drying are carried out separately to achieve the purpose of saving energy, saving time and increasing production. Traditional medicinal use is done by freezing and freeze drying. Some companies in Western Europe and the United States, in order to achieve the same purpose, freeze-dry food, take medicine before freezing, and then enter the dryer to dry.
Figure 8 gives a photograph of the continuous freezing device for drugs.
3. function of vacuum drying equipment to increase
With the electronic and computer technology, the control system and display of vacuum drying equipment have generally increased.
Zhengzhou Research Institute food science corn vacuum drying equipment and simulation automatic screen display function; Shanghai Tofflon, Beijing and other manufacturers produce the original speed, vacuum freeze dryer to determine the final freeze-drying, freeze-drying curve design, see To the operation, some freeze-drying curve storage, printing of various functions, such as production information.
Vacuum drying equipment has more functions in foreign countries. Most of them have a manipulator that can take samples for testing during the drying process; some types of rotary vacuum drying equipment have the functions of crushing and granulating; medicines can also use freeze-drying and granulating equipment.
Several points of development of vacuum drying equipment
1) Innovation is the fundamental way out for the development of vacuum drying equipment
At present, an important reason for the slow development of vacuum drying equipment is that they imitate each other and lack innovation at the same technical level. Ability to imitate, fast, innovative concepts, poor, less input. The competition in the market focuses on robbery, Sino-Latin America relations, and price wars.
A better way is some efforts on quality and after-sales service. However, the development of these vacuum drying equipment, a good way, must invest human, material and financial resources to innovation.
2) The development of energy-saving vacuum drying equipment is the key
Energy shortage has always been a concern in the world, and the conventional wisdom is that vacuum drying equipment consumes high energy because it increases the need for vacuum pumps.
But there is no comparison of real energy consumption for the same material, dry with the same moisture content. In fact, vacuum drying in a closed space is low-temperature drying with relatively little wasted energy. However, energy-saving vacuum drying equipment is still the key to development.
Compared with other types of drying equipment, the focus of vacuum drying equipment should be energy saving
Reasonable design, selection and use of vacuum systems.
There are not many steam vacuum pumping systems, and there are currently two categories, direct pumping steam pumps, mainly water jet pumps, steam jet pumps, water ring pumps and Roots wet pumps; the other method is to collect condensed water. There are two ways for this relatively high energy consumption, the direction of the former energy-saving pump should be to improve the efficiency of the exhaust, and the design direction of the latter is the energy-saving gas-solid phase transition, such as thermal structure and thermal efficiency.
3) Continuous vacuum drying equipment is an important means to improve product yield and save energy
Compared with continuous vacuum drying equipment, compared with the cycle of vacuum drying equipment, it reduces auxiliary, saves time and improves output. At the same time, he does not have to cycle the vacuum drying equipment, which produces a cycle of high and low temperature changes, as a result, part of the energy is wasted in duplicating the content of the heating equipment. Therefore, save energy.
4) The production mode combining vacuum drying equipment and other drying methods should be advocated
Vacuum drying combined with other drying methods can increase productivity and reduce product costs. For example, vegetables, aquatic products, fruits and other products, the use of vacuum drying can ensure the quality of the product, if after a vacuum drying, before washing, blanching, centrifugal dehydration, and then drying, to eliminate the cold of the surface water, and then enter the vacuum drying Equipment, to achieve a significant increase in production efficiency, while reducing production costs. Freeze drying combined with spray is a combination.
Many combinations can be experimented to find out, and of course, time, effort and money must be expended.
Innovation of vacuum drying equipment.
There are also many issues, such as close cooperation between production, learning and research, in order to achieve more significant results.