Application of microwave low-temperature drying equipment in pharmaceutical industry
Microwave vacuum drying equipment is a new type of microwave energy application equipment that combines microwave energy technology with vacuum technology. It combines a series of advantages of microwave and vacuum drying. The flash dryer overcomes the disadvantages of long drying cycle and low efficiency of conventional vacuum drying. In the general material drying process, it can improve efficiency by 4-10 times compared to conventional methods. The microwave vacuum flash dryer equipment has the advantages of high drying yield, good quality, and low processing cost. It is a high-tech product that integrates multiple disciplines such as electronics, vacuum science, mechanics, thermodynamics, and program control. It is a new technology and process developed based on in-depth research on the physical changes of substances, internal and external heat and mass exchange, and water migration under vacuum conditions during the drying process. In industrial large-scale production, there are many items that cannot be dried under high temperature conditions, such as some drugs, chemicals, nutritional foods, and high-end Chinese medicinal materials such as ginseng and deer antler. In order to ensure product quality, their drying treatment must be carried out at a temperature below 100 ℃ or at room temperature. As is well known, the boiling point of water also decreases with the decrease of air pressure. For example, at one atmosphere (101.3kpa), the boiling point of water is 100 ℃, while at 0.073 atmosphere (7.37kPa), the boiling point of water is 40 ℃. Under vacuum conditions, heating an object can cause the internal moisture of the object to evaporate in a non heated state. Due to the difficulty of convective heat transfer in air under vacuum conditions, the only way to provide thermal energy to materials is through thermal conduction. The conventional vacuum drying method has slow heat transfer speed, low efficiency, and difficulty in temperature control. Microwave heating is a type of radiation heating that involves direct interaction between microwaves and materials, heating both inside and outside without the need for convection or conduction to transfer heat. Therefore, it has fast heating speed, high drying efficiency, and easy temperature control.
Developed countries abroad began developing industrialized microwave vacuum drying equipment in the 1980s and achieved good results in practical applications. French International Microwave Company uses microwave vacuum drying equipment to process seedless raisins, changing the traditional process of 65 ℃, 24-hour hot air drying to 50 ℃, 5-hour microwave vacuum drying, greatly improving product quality and yield. In the late 1990s, our unit began to develop microwave vacuum equipment in China. After several years of effort, we completed the industrial development of 10KW microwave vacuum drying equipment in 2000. This provides a new and efficient drying equipment for pharmaceutical engineering, biotechnology, chemical engineering, materials engineering, and deep processing of agricultural and sideline products.
2、 Advantages of Microwave Vacuum Drying Equipment
1. Efficient
Conventional vacuum drying equipment uses steam for heating, which requires heating from the inside out and consumes a large amount of coal due to slow heating speed. In contrast, microwave vacuum drying equipment uses electromagnetic wave heating, which does not require a heat transfer medium and directly heats the inside of the object. The heating speed is fast, and 1 kW of microwave can heat water at room temperature to 100 ℃ in 3-5 minutes, avoiding the above disadvantages. Therefore, it has fast speed, high efficiency, greatly shortened drying cycle, and reduced energy consumption. Compared with conventional drying techniques, it can improve work efficiency by more than four times.
2. Heating evenly
Due to microwave heating, the material is heated simultaneously from the inside out, and the temperature difference between the inside and outside of the material is very small, which does not produce the inconsistent heating situation that occurs in conventional heating, thus producing a puffing effect, which is conducive to crushing and greatly improves the drying quality.
3. Easy to control, convenient for continuous production and automation. Due to the fast adjustment and inertia free characteristics of microwave power, it is easy to control in real time and can operate between 40 ℃ and 100 ℃
adjust the temperature
4. Small backup size, easy to install and maintain
5. The product quality is good, and compared with conventional methods, the quality of the processed products has been significantly improved.
6. Microwaves have disinfection and sterilization effects, ensuring product safety and hygiene. Long shelf life.
7. The economic benefits are significant.
From the characteristics introduced above, the significant economic and social benefits can be seen in terms of energy conservation, consumption reduction, improvement of product quality, safety and hygiene, and low equipment investment costs.
3、 Basic structure and working principle
1. Process diagram of microwave vacuum drying equipment applied in the processing of valuable medicinal materials (omitted)
4、 Circuit Control Design
1. Circuit composition diagram (omitted)
5、 System Design
1. Vacuum pump selection
2. Material turntable design
3. Whole machine thermal balance design
4. Power regulation design
6、 Economic Benefit Analysis
A pharmaceutical factory in Jiangxi province compared the process performance, economic benefits, and product quality of various drying equipment. The drying indicators were compared as follows:
Project dynamic microwave drying spray drying flash dryer
Drying time 45~70 minutes 3~5 seconds 20~45 hours
Drying temperature 45~60 degrees (arbitrary setting) Inlet air 180 degrees 50~60 degrees (difficult to control)
Extract loss of 0~5%, over 3%
Moisture content 4-5% 2-4% 4-6%
Content loss increases by 20-30% compared to other equipment, decreases by 20-30%, and decreases by 20-30%
Under the same production conditions, one unit requires 3 units and five units are needed
The cost per kilogram of dry paste is 0.4~0.5 yuan/kg 3~4 yuan/kg 3~4 yuan/kg
Drying method: process configuration
It can be seen from the above that the drying cost is low, the benefit is good, and the equipment occupies a small area, which is equivalent to 20% of the area of the steam vacuum dryer and 30% of the spray drying equipment, greatly saving the purification plant. Dynamic vacuum microwave dryer is not only suitable for traditional Chinese medicine extracts facing health products, food and chemical products, especially for paste like and high viscosity materials; It can also have a better effect on killing bacteria.
7、 Conclusion
The successful development of industrialized microwave vacuum drying equipment has filled the gap. This high-tech equipment has greatly promoted the development of national technology, especially the development of China's pharmaceutical industry, which will have a profound impact. At the same time, its successful development has opened up a broader field for the application of microwave energy.
The successful development of this product has led to breakthroughs in many key technologies, and has also provided some theoretical basis and methods for design. In practice, valuable experience has been gained, laying a solid foundation for the further development of this technology.
Actual operation has shown that the equipment has excellent performance, advanced technology, and reasonable design. It is a new technology and product with significant economic benefits, good social benefits, and high promotion value.
