Pilot freeze dryers are common in daily life. Air freeze-drying technology, referred to as freeze-drying, is also known as sublimation air drying. Freeze-drying is a specific method of pre-freezing water-containing materials and then subliming them in a vacuum state to obtain air-dried objects. The original biological and chemical properties of the freeze-dried objects are basically unchanged, and they are easy to be stored for a long time. After being soaked in water, they can be restored to the form before freeze-drying, and their original biochemical properties can be maintained. Therefore, freeze-drying technology is widely used in various fields such as industrial chemistry and medical equipment. However, many people are not very clear about how to use it specifically, and they are not very aware of the precautions. Next, let us learn more about the pilot freeze dryer. First of all, let's take a look at how it works and get ready to work.
Before use, place the object to be air-dried in a low-temperature refrigerator or liquid nitrogen to make the object freeze solid, and then freeze-drying can be performed. The main engine and the vacuum pump are connected with each other by a vacuum tube, and standard clamps are used at the connection. The clamp contains a sealing rubber ring. Before connecting, apply an appropriate amount of vacuum grease on the rubber ring, and then clamp it with the clamp. There is a power socket for the vacuum pump on the right-side panel of the main unit, and the power cord of the vacuum pump is connected well. Check the vacuum pump to confirm that the vacuum pump oil has been filled, and it cannot be run without oil. The oil level should not be less than the centerline of the oil mirror. The "o" type sealing rubber ring above the cold trap of the main unit should be kept clean. When using it for the first time, a thin layer of vacuum grease can be applied. The plexiglass cover is placed on the rubber ring and rotated a few times, which is conducive to sealing.
The main methods of pressure control of the pilot freeze dryer are: ① the control method of the septum valve; ② the control method of the water vapor condenser; ③ the control method of the small butterfly valve; ④ the aeration method.
1. Septum klapanni boshqarish usuli
Suv bug'ining qisman bosimini oshirish uchun quritish qutisi va uchuvchi{1}}miqyosli muzlatish quritgichining suv bug'i kondensatori orasidagi o'tish joyining -kesima maydonini sozlash orqali bosimni nazorat qilish maqsadiga ishora qiladi. quritish qutisi.
2. Suv bug'ining kondensatorini boshqarish usuli
Suv bug'ining kondensatorining kondensatsiya quvvatini kamaytirish uchun sirt haroratini oshirish orqali bosimni nazorat qilish maqsadida ish usulini nazarda tutadi, buning natijasida quritish qutisidagi suv bug'ining qisman bosimi ortadi.
3. Kichik kelebek vana nazorat qilish usuli
Qutidagi bosimni nazorat qilish maqsadi suv bug'ining kondensatori va vakuum pompasi orasidagi valfni vaqti-vaqti bilan ochish yoki yopish orqali erishiladi. Kichkina kelebek valfni boshqarish usuli nazorat qilish tizimidan yuborilgan signal orqali valfning ochilishi va yopilishini nazorat qiladi. Bosim belgilangan qiymatdan yuqori bo'lsa (ya'ni vakuum darajasi juda past), vana ochiladi; bosim belgilangan qiymatdan past bo'lsa (ya'ni, vakuum darajasi juda past) yuqori), valfni yoping. Biroq, bu vaqtda kondanserning harorati juda past bo'lsa, mahsulot rafining harorati ham juda past. Sublimatsiya tezligining sekinlashishi tufayli suv bug'ining qisman bosimi pasayishda davom etadi. Ayni paytda uchuvchi muzlatish quritgichidagi bosim belgilangan qiymatdan pastroq Biroq, bu usul ichki bosimni oshira olmagani uchun bosimni sozlash maqsadiga erishib bo'lmaydi.
4. Shamollatish usuli
Mikro{0}}nazorat valfi orqali havo kirishini boshqarish orqali quritish qutisiga steril havo yoki azot kiritishning ishlash usuli. Ushbu usul odatda haqiqiy ishlab chiqarishda qo'llaniladi, lekin u ham ba'zi kamchiliklarga ega:
①Since the introduction of mostly non-condensable gas (air or nitrogen), the existence of this gas reduces the effective condensation area of the condenser, which makes the condenser prone to ice blockage, and the introduction of nitrogen will also increase the cost.
②Because the gas is introduced from the outside, the cleanliness of the gas directly determines the quality of the product, which is easy to cause pollution and cause the product to have hidden dangers in quality and safety.
③With the alternation of air aeration and high vacuum, the products with a lighter texture and less filling volume are constantly reciprocating up and down. During this process, the friction between the product and the bottle wall makes the formed product into powder. And being taken away not only affects the loading and content of the product but also affects the appearance of the product.
④Due to the direct introduction of gas from the filling room, the normal fumigation and disinfection work in the clean area cannot be carried out, and there are two identical ones that cannot be accelerated, thus hindering the production progress. Although the above methods can achieve the purpose of pressure control, they all have various disadvantages. The degree of vacuum is directly determined by the vacuum pump, so it is recommended to start with the vacuum pump, study the variable frequency vacuum pump, and then automatically control the switch and running speed of the pump through the indoor pressure, so as to fundamentally solve the problem of pressure control. At the same time, due to the power of the vacuum pump being Smaller, it can also save energy.
