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The Shanghai Yetuo Experimental Freeze Drying Machine is manufactured using the principle of freeze-drying in a vacuum environment and is currently a relatively advanced equipment for material dehydration. It has the advantages of compact and reasonable structure, convenient maintenance, fully automatic control, and easy operation, and is widely used in deep processing such as pharmaceutical industry, food industry, materials science, agricultural and sideline products, scientific research, and even ancient calligraphy and painting restoration and plant specimen production. So, what is its working principle? How should it be used?
1. Working principle of Shanghai Yetuo experimental freeze-drying machine
The experimental freeze dryer is designed for the renovation and upgrading of existing conventional vacuum drying and drying ovens, mainly consisting of a refrigeration system and a vacuum system. Its working principle is to use the principle of vacuum drying to freeze wet materials to the eutectic point temperature, turning the moisture in the materials into solid ice. Then, in a higher vacuum environment, the ice is directly sublimated into water vapor by heating the materials. The water vapor is then condensed by a water vapor condenser in the vacuum system to achieve the purpose of material dehydration and drying.
2. Advantages of Shanghai Yetuo Experimental Freeze Drying Machine
1. Has fast drying speed and reduces time by 3-10 times;
2. Low energy consumption, only 20% -30% of the energy consumption of ordinary dryers;
3. Wide drying temperature range (can dry at -55 ℃~120 ℃), capable of rapid drying in low temperature range (-20 ℃~50 ℃);
4. The vacuum in the drying chamber is oxygen free, and the drying quality can be comparable to the quality of fresh raw materials;
5. It can recycle organic solvents, which is beneficial for reducing production costs and environmental protection, especially suitable for materials containing organic solvents that cannot be dried by ordinary dryers.
6. Vertical open door structure, capable of in-situ freeze-drying of materials;
7. The control system is centered around PLC and uses a touch screen as the human-machine interface. It records real-time temperature data from multiple channels during the freeze-drying process and can be browsed in curve form. The human-machine interface is clear and intuitive.
8. Pre set shelf temperature control curve to achieve automation of sublimation process.
9. The host is equipped with a USB interface, which allows real-time uploading of freeze-dried data to the computer and enables functions such as saving, browsing, and printing.
10. It can reduce the possibility of material oxidation and deterioration, eliminate bacteria in the material, and ensure quality; Meanwhile, the original appearance of the material can be well preserved
3. Composition of Shanghai Yetuo Experimental Freeze Drying Machine
It usually consists of six major components: drying chamber, condenser (water trap), heating system, vacuum system, refrigeration system, and electrical control system.
1. Drying chamber
A closed container that integrates vacuum pumping and heating drying functions. The sublimation drying process of materials is completed in the drying chamber. The materials are placed in stainless steel trays on the shelves in the drying chamber, and are loaded at a ratio of 8-12 kilograms per square tray area. Each shelf has a probe for measuring the temperature of the materials to monitor the temperature of the entire freeze-drying process.
2. Water trap (cold well)
It is a closed device for condensing and sublimating water vapor, usually located at the rear of the drying chamber. There is a large area of metal adsorption surface inside, and the water vapor sublimated from the materials in the drying chamber can condense and adsorb on its metal surface. The working temperature of the adsorption surface can reach -45 ℃~-65 ℃. The condenser is made of stainless steel or iron in the shape of a cylinder, and there are condenser tubes inside, which are connected to the refrigeration unit to form a refrigeration cycle system.
3. Heating system
The function of the freeze-drying machine heating system is to heat the materials inside the drying chamber, causing them to continuously sublime and reach the specified moisture content requirements. The heating methods of the freeze-drying machine heating system are mainly divided into contact heating and radiation heating.
In contact heating, the circulating medium heating method is used. When the heating system is working, the circulating liquid is first heated, and the liquid temperature is automatically controlled by the temperature selected by the liquid box control regulator. After the pipeline pump is turned on, the circulating liquid can be sent to the shelf in the drying box to heat the shelf, and then returned to the liquid box for heating circulation.
In radiation heating, we usually use steam heating. When the circulating medium is silicone oil, the highest temperature of the separator can reach+120 ℃.
4. Vacuum system
The vacuum system consists of multi-stage vacuum pumps or water ring pumps and Roots vacuum pumps. Roots pumps are booster pumps and cannot be used alone. The vacuum pump or water ring pump must be activated first to work for a period of time. When the vacuum degree in the system reaches below 1Kpa, the Roots pump will automatically start. The structure of the vacuum pump and Roots pump can be found in the instruction manual. The vacuum gauge of the vacuum system can use an electric contact vacuum gauge, which can automatically control the start of the Roots pump according to the pre selected vacuum degree value.
5. Refrigeration system
The freeze-drying refrigeration system consists of a refrigeration compressor unit and R22 or R404a refrigerant. Usually, the quick freezing refrigeration system and the water trap refrigeration system of freeze-drying equipment share the same refrigeration system. When the system is working, the temperature of the shelf in the contact heating mode can be reduced to -35 ℃. When the refrigeration system is working, the surface temperature of the condensing coil can reach -35 to -65 ℃. Low temperature screw or two-stage piston refrigeration compressor units can be used according to customer needs. Generally, two-stage piston compressors have better refrigeration effects and lower refrigeration temperatures.
6. Electrical control system
4. Application scope of Shanghai Yetuo experimental vacuum freeze dryer
1. It can be used for drying fruits and vegetables, meat and poultry, aquatic products, seasonings, convenience foods, and famous specialty products. It can achieve the purpose of maintaining the original color, aroma, taste, shape, and freshness of the food, and has good rehydration properties. The finished product is easy to store and transport, with reduced costs and extended shelf life.
2. The use of vacuum freeze-drying technology in dried royal jelly, ginseng, turtles, soft shelled turtles, earthworms and other nutritional supplements further enhances people's belief in the purity and naturalness of these nutrients.
3. Used for dehydration and preservation of Chinese and Western medicines such as serum, plasma, vaccines, enzymes, antibiotics, hormones, etc; Blood, bacteria, arteries, bones, skin, cornea, nerve tissue, and various organs that can be stored for a long time can be regenerated with only water supply during use, while still maintaining their biophysical properties. Working principle, composition, advantages, application, operating procedures and maintenance points of vacuum freeze dryer The development trend of vacuum freeze dryer With the expansion of the industry and the pursuit of productivity and energy consumption reduction, vacuum freeze dryer often combines with other equipment to form a drying equipment combination, such as spray vacuum freeze dryer. Alternatively, other drying techniques can be combined with it, such as microwave vacuum freeze dryers, which not only improve the problem of poor heat transfer in vacuum environments through microwave heating, but also facilitate the diffusion of water vapor due to the high sublimation interface temperature, making them more suitable for drying thermosensitive materials. Guidelines for the use of vacuum freeze dryers
1. The preparation of samples should maximize their surface area and should not contain any acidic or alkaline substances or volatile organic solvents. The sample must be completely frozen into ice, as any residual liquid may cause gasification spray. Note that the cold trap is about minus 65 degrees Celsius and can be used as a low-temperature refrigerator, but it must be operated with insulated gloves to prevent frostbite.
2. Before starting the vacuum pump, check whether the outlet valve is tightened, whether the inflation valve is closed, whether the contact surface between the organic glass cover and the rubber ring is clean and free of dirt, and whether it is well sealed. In general, the machine should not be used continuously for more than 48 hours.
3. Turn on the main power switch on the left side of the vacuum freeze-drying machine chassis, and the air pressure digital display shows atmospheric pressure 110pk. Press and hold the main switch on the control panel for more than three seconds, and the temperature display will show the actual temperature of the cold trap.
4. Start the refrigeration unit and pre cool for more than 30 minutes. Place the sample into the sample rack, cover it with an organic glass cover, and start the vacuum pump. After the air pressure digital display stabilizes, record the temperature and air pressure values.
5. During the freezing process, the temperature of the sample gradually decreases. The sample can be taken out and warmed up for a period of time (still in a frozen state) before continuing to dry to shorten the drying time.
6. Record the temperature and air pressure values before the vacuum freeze-drying machine is shut down.
7. Press and hold the inflation valve on the control panel, and immediately turn off the vacuum pump. When the pressure display shows atmospheric pressure, open the organic glass cover and take out the sample.
8. Turn off the refrigeration unit, hold down the main power switch for at least three seconds, and finally turn off the main power switch. After the ice in the cold trap has completely turned into water, open the water outlet valve on the left side of the chassis to release water, clean the inner wall of the cold trap with a dry cloth, and cover it with a large filter paper to prevent dust.
5. Maintenance of Shanghai Yetuo Experimental Vacuum Freeze Drying Machine
1. Maintenance of refrigeration system
1) Daily routine check. The main inspection contents include:
① Are all valves that should be opened open.
② Is the pressure of the compressor within the normal range.
③ Is the pressure and temperature of the cooling water normal.
④ Is the compressor's return oil and oil level normal.
⑤ Is the sound of the compressor running normal.
⑥ Is there any abnormal vibration in the refrigeration pipeline.
⑦ Frost formation on compressors and expansion valves, etc.
If any abnormal situation is found during the inspection, the cause should be identified and dealt with in a timely manner to eliminate potential safety hazards.
2) When the equipment is not used for a long time, the refrigerant should be stored in the condenser to prevent refrigerant leakage. During the production process, the refrigeration system should be regularly checked for leaks to ensure that any leaks are promptly addressed. If the refrigerant is insufficient, it should be promptly filled to avoid affecting the normal operation of the equipment.
2. Maintenance of Shanghai Yetuo Vacuum System
① Regularly replace the vacuum pump oil to ensure the performance of the vacuum pump.
② Before starting the vacuum pump, check if the oil level is normal, usually at around 1/2 of the sight glass position.
③ Before vacuuming the box, it is necessary to ensure that the back box is dry to avoid pumping water vapor into the pump body, which may affect the pumping efficiency of the vacuum pump.
The above content is a detailed introduction by Xianji.com editor to the working principle, composition, advantages, applications, operating procedures, and maintenance points of vacuum freeze dryers. Vacuum freeze dryer is a process of drying materials under low temperature and vacuum conditions, while maximizing the color, aroma, taste, shape, and nutritional content of the dried materials. The product is highly soluble in water and can quickly recover. After sealed packaging, it has a long shelf life.
The electrical control system of this equipment consists of automatic devices and circuits such as PLC, touch screen, control cabinet, control instruments, and regulating instruments. Its function is to manually or automatically control the freeze-drying machine and ensure the normal operation of the equipment. Working principle, composition, advantages, applications, operating procedures, and maintenance points of vacuum freeze dryer
