Vacuum drying equipment, drying equipment, vacuum dryer

There are many kinds of vacuum drying equipment, which are widely used and developed rapidly. In this paper, the development trends of several vacuum dryers at home and abroad are described in order to realize 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: low oxygen content when drying under low pressure, which can prevent the drying materials from oxidation deterioration

There are many kinds of vacuum drying equipment, which are widely used and developed rapidly. In this paper, the development trends of several vacuum dryers at home and abroad are described in order to realize 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: low oxygen content in drying under low pressure can prevent the drying materials from oxidation and deterioration, and can dry inflammable and explosive dangerous goods; it can vaporize the moisture in the materials at low temperature, so it is easy to dry heat sensitive materials; it can recover valuable and useful components in the dried materials; it can prevent the discharge of toxic and harmful substances in the dried materials, so it can become an environmental protection class Green and dry. Therefore, vacuum drying equipment is widely used.

The main disadvantage of vacuum drying is that it needs a set of vacuum system which can pump steam, which makes the equipment investment cost high and the operation cost high; the equipment production efficiency is low and the output is small. In order to overcome these shortcomings, many scientific and technological workers have made a lot of efforts. At the same time, because vacuum drying has many advantages, some products have to use vacuum drying equipment. Therefore, the development of vacuum drying equipment will have a bright future.

1. The varieties of vacuum drying equipment at home and abroad are increasing. For different purposes, a variety of new vacuum drying equipment have been developed.

1) Microwave vacuum drying equipment can save energy and improve drying rate.

2) the combination of spray freeze drying equipment spray drying and freeze-drying is determined by the nature of the material and the output of the product. The material must be liquid slurry, and after spray freezing, the micro nano scale particles are formed, which increases the drying rate and improves the output of the product.

3) Vacuum vapor phase drying equipment is specially used for drying large oil immersed transformer and other similar electrical equipment. Switzerland developed this product in the 1970s. This kind of equipment was introduced into China in the 1980s. After 1990s, it has been basically completed and can be produced in complete sets.

4) In order to meet the needs of schools and scientific research institutions, several kinds of freeze-drying equipment with different functions have been developed at home and abroad.

5) Lyophilization separation type freeze-drying machine for medicine.

In order to save energy, save time and improve output, freeze-drying machine is used to freeze and dry food separately. Traditional medicine lyophilizers are all freeze and dry in the machine once. Some companies in Western Europe and the United States, in order to achieve the same purpose as food freeze-drying, drugs are pre frozen and then sent to the dryer for drying.

2. The development of continuous vacuum drying equipment at home and abroad is unbalanced

In order to improve the output of equipment and ensure the quality of products, many kinds of continuous vacuum drying equipment were developed abroad more than ten years ago. However, due to the limitation of technical level and people's cognition, the development is relatively slow in China.

1) Belt type continuous vacuum drying equipment

Wl-vaq belt type continuous vacuum drying equipment produced by Japan production Institute is suitable for liquid materials, slurry, paste concentration and high viscosity drying. Bv-100.5 vacuum belt continuous drying device made in Japan adopts steam and conduction heating. The temperature of each section is adjustable, and the tension and speed of conveyor belt are adjustable. The Swiss company has developed a series of belt type continuous vacuum drying equipment with automatic cleaning device.

Since 1995, we have been engaged in the design, manufacture, installation and service of belt continuous vacuum drying equipment.

In 2004, a research institute in Guangdong Province successfully developed a small-scale experimental equipment for banana powder drying, and the effect was very good.

2) Continuous vacuum drying equipment for grain

Because of the large amount of grain drying, continuous drying equipment must be used. In the past, many grain drying equipments have been developed all over the world, and the vacuum drying grain is mostly used for seed drying because of the high cost of vacuum drying. In fact, this is a misunderstanding. According to He Xiang, a senior engineer of Zhengzhou grain science research and Design Institute, the continuous vacuum corn drying equipment developed by them has a production capacity of 60t / D, fixed investment is slightly higher than that of hot air drying, and the operating cost is equal to that of hot air drying. The total cost of vacuum drying at low temperature is not higher than that of hot air drying if the quality of drying products, damage rate and burst waist rate are considered.

3) Continuous vacuum freeze drying equipment

The production of freeze-dried food is very large. Therefore, continuous food freeze-drying equipment appeared earlier. In 1985, a Danish company produced Conrad & ndash; 800 continuous freeze-drying equipment, which is used for the production of freeze-dried coffee, with a production capacity of 13T per day.

The first domestic continuous vacuum freeze-drying equipment was successfully developed by a research institute in Shenyang in 2000. The vacuum chamber is of rectangular structure. There are isolation plates between the inlet and outlet bin and the drying bin. The automatic weighing system is set in the inlet and outlet silos, which can judge the drying rate, water output and final drying degree of freeze-dried food. Two external water traps work alternately to realize continuous water harvesting and ice melting.