The air dryer is suitable for particles and powdery materials that are easy to dehydrate, and can quickly remove material moisture (mainly surface moisture). In air drying, the quality of the dried product is best controlled due to the short residence time of the material in the dryer. The wet material is thoroughly mixed with the hot air stream through the feeder, and dried under the suction of the wind into the drying tube for further uniform drying. The wet weight particles that cannot be attracted by the wind continue to be impacted, broken, and dried in the dryer until they can be sucked into the drying tube by the wind. The end of the drying tube is a cyclone separator. This equipment is mainly used for the production of oxytetracycline and some health products in the pharmaceutical industry.
5, spray dryer
The drying process of a spray dryer is similar to air drying. After the air is initially filtered, it is heated by the heater, and the hot air produced is filtered through several stages (selected according to drug grade), and then the air flow generated by the hot air distributor is uniformly rotated into the drying chamber on the volute passage at the top of the drying chamber. The material is filtered through centrifugal atomizer discs or pressure nozzles to produce a dispersed, fine material mist. The material mist is in contact with the swirling hot air and the moisture rapidly evaporates. The material is dried in a very short time. This equipment is suitable for the drying of liquid materials with good fluidity such as solution, emulsion, suspension, paste, etc. Our company has been using such equipment to produce streptomycin from the 1950s to the present, and now the API industry is like This device can be selected for the drying of streptomycin, gentamycin, and various biological extracts.
6, boiling bed
In the ebullating bed, the medicine is added from the upper part of the bed during the drying process. The hot air is blown in from the bottom and comes into contact with the material of a certain material thickness through the porous distribution plate. The material is in a fluidized and boiling state, and it is turned upside down and mixed in the air flow. With collision, large contact area between gas and solid, intense heat and mass transfer, greatly improve the drying speed and drying efficiency, is an ideal drying equipment. For some of the more humid materials can be dried once to achieve the required moisture index. Fluidized boiling thermal efficiency. Residence time can be adjusted to easily obtain a low moisture product. Size particles can be graded on the bed surface, coarse particles can be discharged from the bed, and fine powder discharged from the dust collector. Some materials, bag dusting can be done in the host (built-in type), saving space, simple structure, less investment. This equipment is suitable for the drying of powder, granules, and silk and strip materials. The equipment is fully enclosed and can be cleaned and sterilized online. It is widely used in the pharmaceutical industry for the production of antibiotics and semi-synthetic chemicals.
7, fluidized bed
The fluidized bed is divided into ordinary fluidized bed and vibrated fluidized bed. The drying of the drug is affected by the fluidity. Most of the fluidized bed is selected. The dryer is excited by the vibration motor to make the machine vibrate. The material leaps forward under the exciting force in a given direction. At the same time, the hot air at the bottom of the bed makes the material in a fluidized state, and the material particles are in full contact with the hot air and violently transmitted. Heat mass transfer process, the highest thermal efficiency at this time. The upper chamber is in a state of slight negative pressure, the humid air is led by the induced draft fan, and the dry material is discharged from the discharge outlet, so as to achieve an ideal drying effect. The equipment is fluidized evenly, with no dead angle, even temperature distribution, and high thermal efficiency. It is suitable for the drying of granules, powders, bars and filaments, and can be used for pharmaceutical intermediates such as starch, glucose and many high-volume production.
8, freeze dryer
Vacuum freeze-drying machine is suitable for the drying of heat-sensitive or easily oxidized chemicals, commonly known as lyophilizer, mainly including lyophilization box, vacuum system, heating system, refrigeration system and so on. According to the shelf area can be divided into small experimental freeze dryer, medium production freeze dryer, large industrial production freeze dryer. Drying of APIs and preparations There are many applications of freeze dryers. The main requirements are its high reliability and complete sterilization function. The temperature difference between the same shelf and the slab is not more than 1.5°C[2], which means that the flatness of the shelf must be better. When using this equipment to dry raw materials, in order to ensure the homogeneity of the product, it is best to add a powder mixer. Ampicillin, a large number of blood products, artificial culture drugs, antibodies, vaccines, etc. are mostly used freeze dryer.
In the past 20 years, with the process of reform and opening up, the pharmaceutical industry has witnessed rapid development. At the same time, the pharmaceutical machine industry has also shown a flourishing situation. The author has had the privilege of having experience in the above drying equipment due to work reasons. Due to the limited knowledge, there are still many good things. The dryers are not described, such as tray dryers, spouted bed dryers, flash dryers, microwave series dryers, and the like. When the dryer is selected, it depends on the characteristics of the drug and the desired state of the finished product. In particular, the material and sterility of the sterile raw material drying equipment must be considered. China's pharmaceutical drying equipment has developed rapidly in Jiangsu Province, and there are many specialized drying equipment factories. Its products are both versatile and have their own characteristics. This is the localization and selection of imported equipment used for drying APIs in line with the quality of pharmaceutical production. The GMP's ideal desiccator provides the conditions.
Principles for selection of dryers in the pharmaceutical industry (2)
4, air drying device