Pressure spray drying is primarily defined by the operating principle of the pressure atomizer, which gives the system its distinctive characteristics.
Since the product obtained via pressure spray drying consists of fine particles, and both the initial droplets and the final product particles are larger than those produced by the other two methods, the drying time for the droplets is relatively long. Additionally, the spray angle is narrow-typically between 20° and 70°-necessitating a tall, tower-like dryer configuration to ensure the droplets have sufficient residence time. The process involves pressurizing the feed liquid and atomizing it through the nozzle, requiring the use of a high-pressure pump within the system. Furthermore, because the atomizer orifice is very small, the feed liquid must be filtered before entering the high-pressure pump to prevent debris from clogging the nozzle passages. Pressure spray drying is most often employed to produce granular products.
