Application of spray drying technology in the production of solid preparations

Spray drying technology uses spray method to disperse the material in the hot gas stream in the droplet state The material is fully contacted with the hot gas and completes the heat and mass transfer process instantaneously, so that the solvent (including water and organic solvent) can be rapidly evaporated into gas, so as to achieve the goal of drying Spray drying technology is widely used in China's pharmaceutical industry In the field of oral solid preparation, it is often used to decompose drugs in the process of high heat sensitive drugs and liquid liquid thickening The particle size of the product is fine and uniform, and its fluidity and instant solubility are good The technology requirements of oral pharmaceutical raw materials: oral solid preparations are various, and the specific process requirements are also varied During the design and manufacture of spray dryer, Zui aims at making different designs for different varieties so as to achieve the ideal state of equipment and technology In the selection of spray drying machines, the requirements for the production of solid pharmaceutical products are often listed below: 1 Cleanliness requires that the main process of raw material production should be carried out in a clean environment of one hundred thousand levels, and spray drying is an important process of quality control The contact parts of spray dryer should be made of stainless steel Zui stainless steel is suitable for 316L with strong corrosiveness Dry chamber, cyclone separator, filter and other parts directly contacting with materials shall have smooth inner wall, no dead angle, easy to clean, easy to dismantle and easy to clean Spray dryer often has a large system, so it can not be put in the clean area as a whole It often only puts part of the collected material in the clean area, which requires that the system has good airtight performance, so as to prevent external pollution from going to the system Two Avoiding sticky wall phenomenon is still a prominent problem that hinders the normal operation of spray dryer The spray drying process of solid preparations (especially Chinese Medicine) is particularly obvious The material sticking to the wall is not only unfavorable to the collection operation, but also with the extension of time, the sensitive sticking materials will deteriorate and become unqualified materials From the point of view of technology, the solutions include choosing suitable solvents, adding auxiliary materials and changing process parameters However, there is not much room for these methods to be adjusted Therefore, it is necessary to seek fundamental solutions from the perspective of equipment Experts at home and abroad have conducted in-depth research on the problems of wall sticking and caking in the drying process, and they agree that the main reason for wall sticking is the wall temperature Five possible ways to prevent wall sticking are listed as follows: 1 The wall temperature of the tower is kept below 50 ℃ by using the wall drying tower with air cooling; 2 The secondary air is introduced into the wall of the tower through the tangential direction of the rotating air sheet of the tower wall; 3 An air broom composed of a row of nozzles is installed near the wall of the tower, and it is rotated slowly along the tower wall 4 Increase the air hammer on the tower wall, and force the wall sticking materials to separate through the impact of the air hammer; 5 Increase the processing accuracy, and polish the inner wall of the tower can also reduce the wall sticking Three Automatic control spray drying is a continuous production process with more control points For example, the control points of the closed cycle system include: feed concentration, feed speed, air inlet speed, air inlet temperature, system pressure, differential pressure of each component, gas purity detection, etc it is very difficult to rely on traditional manual adjustment A good automatic control system can make the whole spray drying system run smoothly, reduce the unqualified rate of products and reduce the hidden danger of safety At present, domestic products are lagging behind in automatic control, while some advanced equipment abroad, such as Danish spray dryer, are very mature in automatic control Four The drying effect is due to the need for further completion of the preparation process for oral pharmaceutical ingredients Different requirements for the physical properties of spray drying products are raised in terms of improving the preparation effect and taking the absorption effect of Zui final drugs First of all, the moisture content is the * index of dry products, which is generally required to be controlled in a certain range, not too high or too low Secondly, the drug loading is generally controlled according to the volume, which requires that the bulk density of the product is stable and the fluidity of the product is good Oral granules are often required to be instant Generally speaking, the products with different bulk density can be produced by changing the dispersion of atomization or changing the operating conditions appropriately to control the drying rate, but the range of variation is limited One of the techniques to improve physical properties is foam spray drying, which is about to first foam and then spray dry The method Zui was first proposed to improve thermal efficiency, and later used to adjust the physical properties of products It has been proved that the products produced by foam spray drying are large, porous, concave and rough, and have good instant solubility In addition, oral APIs have some special requirements, such as particle shape Some require spherical particles with uniform size In general, particles of different shapes can be obtained by changing the atomization mode Before choosing the spray dryer, API Zui is very good at the experiment of parameter optimization with the help of equipment manufacturers, so as to determine an ideal parameter combination to ensure the drying effect of the ejected drugs V due to the different nature of drugs, protection measures also put forward some higher requirements for the protection design of equipment For materials dissolved in organic solvent, the whole system must meet the explosion-proof requirements when drying Explosion proof type shall be selected in the design of motor, instrument, control valve and other accessories In addition, in order to prevent the mixture of solvent and air into explosive gas, the system can not be open type, but must adopt closed circulation system, and the carrier should choose inert gas, such as nitrogen, etc In addition, the airtight circulation system with nitrogen as carrier should also be used for drying some easily oxidized materials Vi environmental protection The spray drying products are fine particles In order to meet the requirements of environmental protection, the spray drying system only separates the products and purifies the exhaust gas by cyclone separators It is still not enough Generally, it uses bag filter to purify so that the dust content in the tail gas is lower than that of 50mg/ (nm) 3 gas Or the wet dust scrubber can be used to reduce the dust content of the tail gas to 15~35mg/ (nm) 3 gas When nitrogen is used as carrier, the system shall be closed and the exhaust port shall be led to the outside 7 To reduce the cost, the inlet temperature of hot air is 250-500 ℃ in parallel flow operation, 200-300 ℃ in reverse flow operation, and the outlet temperature after atomization and drying is generally controlled at 60-100 ℃ The thermal efficiency of spray drying is low, and the industrial scale spray dryer is generally 30%~50% in thermal efficiency Foreign spray drying with waste heat recovery, thermal efficiency can reach 70%, but this device is only in production capacity greater than 100kg (water) /h only economic significance However, when nitrogen carrier and organic solvent are used, the closed circulation system can make nitrogen recycle and solvent condense, thus effectively reducing the production cost Changzhou Zhiyang Machinery Equipment Co., Ltd is a large-scale production of solid preparation equipment company Our company constantly improves the level of technology in the production of spray drying equipment, and solves the technical problems of spray drying in the field of oral pharmaceutical raw materials It also hopes that our customers will find practical problems in the process of using equipment, and we will respond in a timely manner, so that our equipment can be done well and beautifully It is believed that in the near future, we will be able to produce more suitable, high quality and low price products, and make our spray drying technology reach the high level of Zui in the world.