Spray dryer process

The spray dryer feed liquid is atomized by the atomizer, dispersed into fine mist droplets into the drying chamber, and at the same time, the heated gas is sent to the heater through the blower to heat up, and then enters the drying chamber. The liquid droplets are thoroughly mixed and contacted with the hot gas in the drying chamber. The droplets evaporate instantaneously into a gas, and the material is dried into fine particles. The mixed gas-solid two-phase is separated into the cyclone by the induced draft fan, and the solid material is settled to the bottom collector, and the gas phase is led to the dust filter to capture the escaped material. After the filtered gas phase is condensed by the condenser, the carried solvent becomes a liquid, which can be collected and used, and the gas as a carrier is dried and recycled in the system.

Process requirements for solid preparations

There are many kinds of solid preparations, and the process requirements are also very different. In the process of designing and manufacturing the spray dryer, Zui makes different designs for different varieties to achieve the state of equipment and process.

Cleanliness requirements

The main process of API production needs to be carried out in a clean environment of 100,000 grades. Spray drying is an important process of quality control. The part of the spray dryer that contacts the material should be made of stainless steel. For the acid corrosive material, 316L stainless steel is used. The parts that directly contact the material such as the drying chamber, the cyclone separator, and the filter should be smooth inside the wall, have no dead angle, and are easy to disassemble for easy cleaning. Spray dryers tend to be bulky, so they cannot be placed in a clean area as a whole, and often only the part where the material is collected is placed in a clean area, which requires good system sealing performance to prevent external contamination of the system.

Avoid sticking

The sticking phenomenon is a prominent problem that hinders the normal operation of the spray dryer , and the spray drying process of the solid preparation (especially the traditional Chinese medicine) is particularly obvious. The sticky wall of the material is not only unfavorable for the collection operation, but as time goes on, the sensitive sticky wall material will deteriorate into a non-conforming material. From a process point of view, the solution includes selecting the right solvent, adding the excipients, and changing the process parameters. However, there is not much room for adjustment of these methods, so a fundamental solution must be sought from the perspective of the equipment. Experts at home and abroad have studied the problem of sticking and agglomeration during the drying process. It is believed that the main cause of sticking is the wall temperature.