At present, there are still many problems to be solved in freeze dryers, but with the progress and development of science and technology, these problems will not be difficult. Firstly, the function of the freeze dryer is to freeze a substance containing a large amount of water or other solvents into a solid in advance, and then under a certain vacuum condition, make the water or other solvents in the form of steam directly sublimate from the solid, The substance itself remains in the ice shelf when it is frozen. The substance after the drying equipment has the same volume as before drying, but is loose and porous, and has good rehydration.
Freeze dryer is mainly composed of control system, vacuum system, refrigeration system and circulation system. In addition to the above components of medicinal freeze dryers, there are also hydraulic systems, cleaning systems in place and sterilization systems in place. The medicinal flash dryer is the key equipment in the production of sterile freeze-dried preparations. Due to the special nature of medicines, relevant departments have made clear regulations on the materials and performance of freeze-dryers. Although the current freeze dryer has met the production requirements, there are still the following deficiencies in terms of economic benefits, product quality, and production operations. The main point is that the vacuum is too high, which is not conducive to product sublimation!
During the freeze-drying process, the vacuum of the environment in which the product is located has a direct impact on the length of the freeze-drying cycle. If the vacuum degree is too low, the sublimation rate will drop obviously; if the vacuum degree is too high, the heat convection conduction will be too poor, but the freeze-drying rate will also drop significantly. Therefore, various approaches must be taken to control the pressure to achieve the best conditions required for product drying. The main methods of pressure control are: ① septum valve control method; ② water vapor condenser control method; (where the water vapor condenser control method refers to increasing the temperature of the surface of the water vapor condenser to reduce its condensation ability, resulting in water in the drying box The operating method of the vapor partial pressure rise, so as to achieve the purpose of pressure control. ③ Little butterfly valve control method; (Little butterfly valve control method refers to the purpose of controlling the pressure in the tank by intermittently opening or closing the valve between the water vapor condenser and the vacuum pump. The small butterfly valve control method controls the opening and closing of the valve by a signal from the control system. When the pressure is higher than the set value, the valve is opened; when the pressure is lower than the set value, the valve is closed. But if the condenser is at this time The temperature of the product is very low, and the temperature of the product shelf is also very low. As the sublimation speed is slowed, the partial pressure of water vapor is continuously reduced. At this time, although the indoor pressure of the freezing spray drying equipment is lower than the set value, this method cannot Increase the indoor pressure, so that the purpose of adjusting the pressure can not be achieved.) ④ aeration method.
But although these four pressure control methods are widely used, there are still many problems in practical application. Let us look forward to more advanced methods and more perfect systems. Dongguan Guansheng Machinery Co., Ltd. will also be the first Time will share the latest information of the freeze dryer with everyone, welcome to log in to our official website http://ylscps.com
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