Laboratory spray technology for small spray drying technology
Drying plays an important role in pharmaceutical production. In recent years, there are many drying technologies and equipment suitable for the production of traditional Chinese medicine. Spray drying is one of the more advanced methods in drying technology (laboratory small spray dryer). Due to its high drying efficiency, less damage to active ingredients, dissolution of extract powder It is suitable for industrial production and has been increasingly used for the drying of Chinese herbal extracts and the development of new products. At present, there have been reports on the use of this technology to prepare microcapsules and apply PVA for film coating. Therefore, spray drying technology plays an increasingly important role in the production of traditional Chinese medicine and the development of new dosage forms.
1 Basic principles, equipment and processes Spray drying is a better method for fluidized technology for drying liquid materials. The basic principle is to use a nebulizer to spray a certain concentration of liquid material into a mist-like droplet, which falls in a hot gas stream of a certain flow rate, so that it is quickly dried to obtain a powdery or granular product. Its characteristics are: instant drying, especially suitable for heat sensitive materials; good product quality, maintain the original color and fragrance, and easy to dissolve;
The quality index such as the thickness and water content of the product can be adjusted and controlled as needed; the preparation volume is small; it is beneficial to the hygiene of the preparation. The spray drying equipment generally consists of a drying chamber, a spray head, an air filter, a preheater, a gas separation chamber, a collection tank, and a blower. Sprayers are a key part of spray drying equipment, which affects the quality and energy consumption of the product. There are three types of commonly used laboratory small spray dryers: pressure small spray dryers, airflow small spray dryers, centrifugal small spray dryers. The pressure type small spray dryer is widely used, it is suitable for viscous liquid medicine, and the power consumption is small. The airflow sprayer is simple in construction and suitable for any viscosity or slightly solid solution. Centrifugal sprayers are suitable for high viscosity or drying with solid pellets, but at a higher cost. There are also flow granulation dryers, powder spray towers and automatic intermittent spray dryers for teaching and research. The simple process of spray drying is: medicinal material - → extraction - → concentration - → spray - → collect powder. Specific operation process (pressure spray drying)
The following is as follows: the Chinese medicine decoction piece is placed in the extraction tank for steam leaching several times. The leaching solution is pumped into the decompression concentration tank through a vacuum suction tube, concentrated to a certain concentration, and the drug is passed through the flow meter to the nozzle under the nozzle to enter the compressed air of the nozzle (39123) ×104～49104×104Pa), the chemical liquid is sprayed into the drying chamber by the centrifugal force by the centrifugal force by the vortex device, and then mixed with the hot air stream for heat exchange, and then dried quickly. After the blower is turned on, the air is heated to about 280 °C through the filter and the preheater, and enters the drying chamber in the tangential direction from the upper part of the drying chamber. The drying chamber is generally kept below 120 ° C, and the dried fine powder falls into the collecting barrel. The partially dried powder is trapped in the bag after entering the separation chamber with the flow of hot air, and the hot exhaust gas is discharged from the exhaust port.
Applications
2.1 Low-sugar type Jingwu granule preparation equipment: FL2120 spray drying granulator.
Prescription: 250g of Polygonum multiflorum, 250g of Polygonatum, 125g of Ligustrum lucidum, 125g of Eclipta.
Preparation Process:
1 extraction: the above 4 flavors, boiled several times with water, filtered, and the filtrate was concentrated to a relative density of 1108 ~ 1110 (60 ° C), alcohol precipitation, the supernatant recovered ethanol and concentrated to a relative density of 1121 ~ 1125 (80 ~ 85 ° C )spare.
2 granulation: Calculate the amount of raw and auxiliary materials according to the actual needs of production. The auxiliary material (sucrose or dextrin, particle size 40-60 mesh) is put into the boiling granulating pot, and the hot air is sent, and the air is preheated and dried (the preheating drying temperature of the auxiliary material is about 80 ° C), and the chemical solution is intermittently sprayed into the auxiliary material. Coagulate into porous particles (spray granulation temperature 80 ~ 110 ° C, air temperature 40 ~ 50 ° C), after sampling and inspection, the discharge, the whole grain is obtained.
2.2 Preparation of musk volatile oil microcapsules Preparation process: Take a certain amount of musk volatile oil, add different proportions of water, polymer gelatin (water-soluble membrane) and stabilizer, and stir it in a chopper to make uniform The emulsion is spray dried. Drying conditions: inlet air 146 ° C, air outlet 87 ° C. Pay attention to controlling the proportion of the amount of membrane material in the emulsion. The experiment shows that the membrane volume is greater than 70% of the water content, and the volatile oil retention rate is higher.
2.3 Dengqi Xixin capsule PVA film coating equipment: LF2120A fluidized bed spray drying granulator.
Preparation process: ç› ç› è¾› 乙醇 乙醇 ethanol reflux extraction, concentrated under reduced pressure (about 1135 specific gravity), to obtain a clear paste, vacuum drying at low temperature, granulation, sieving. The film was coated on the fluidized bed spray drying granulator with PVA17-88 solution as the slurry. Operating conditions: inlet air 100 ° C; outlet air 60 ° C; spray pressure 2 kg; flow rate 1000 ml ?? min. After the coating is completed, the sieve is taken out and filled to form a capsule. The experimental results show that the dissolution rate of the capsules coated with PVA is not affected, and it is easy to be encapsulated, and the stability is greatly improved. 3 Prone to problems and solutions Spray drying, if used improperly, can cause problems such as clogging the nozzle, sticking walls, agglomeration, etc., thus affecting the drying quality [12-15].
The above problems may be related to the following factors.
(1) improper selection and installation of drying equipment. The vertical cone structure drying tower is easy to cause sticky walls in the cone part, and the vertical cylinder structure can overcome this disadvantage. Unreasonable structural design of the atomizer or improper installation can also cause sticking. When the gas passage and the liquid passage axis of the pressure type and airflow atomizer do not coincide, the large mist generated is not adhered to the wall surface to cause sticking when the surface is dry. Or the nozzle axis is not on the center of the tower when installed, and it will also cause sticking.
(2) Improper handling of the liquid. The pre-spray solution must be filtered to remove coarse particles. Unfiltered or concentrated concentrated and water-extracted and alcohol-treated liquids are prone to blockage of the nozzle. The relative density of the concentrated liquid is generally 1110 to 1125 g?? ml (50 to 60 to 80 ° C). The drying of the liquid after the water extraction and alcohol precipitation must be pre-tested. It is also possible to spray 10% to 40% of dextrin or 1% to 5% of micropowder silica gel together in the chemical solution.
(3) The drying temperature is not properly selected. Pressure or airflow spray dryers generally have an inlet air temperature of 130 to 150 to 180 ° C, and the outlet air temperature is generally lower than 120 ° C (80 to 90 to 110 ° C). It should be based on the nature of the material being dried. For low-melting materials, the high temperature zone in the tower should not be controlled to exceed the melting point of the material, otherwise the wall sticking phenomenon may occur.
(4) The flow rate of the chemical liquid is unstable, and the sticky wall is also generated. The closed storage tank can be used to feed the compressed air at a constant pressure.
(5) Improper post-processing. If the liquid is thicker and has a higher viscosity, it will be shut down immediately after spraying, and the nozzle is prone to blockage. The pipe and nozzle should be flushed with a proper amount of hot distilled water for 5 to 10 minutes before shutting down. In the production of traditional Chinese medicine, the spray-dried extract powder has been used in the production of granules, tablets, pills and capsules, and has received good results. From the current research trend, spray drying will change the current status of drying only for drying, and gradually develop in the direction of combining drying technology with formulation technology. Research on drying equipment also tends to be a multifunctional combination. From this point of view, spray drying technology will have broad application prospects in the development of new drug formulations.
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