Chinese medicine extract and plant extract are the hardest feeds a spray dryer faces: high viscosity, high sugar content, strong hygroscopicity and a tendency to stick on a hot wall and scorch. The ZPG series herbal extract centrifugal spray dryer was designed around that problem. A three stage air purification train brings the inlet air to a clean room grade, a cooling wall keeps the tower shell below 80 °C so the deposit on the wall never carbonizes, and an air sweep device