The external circulation evaporator mainly consists of five parts: heating chamber, separation chamber, condenser, cooler, and liquid receiving tank. It can be used in industries such as pharmaceuticals, food, and chemical industry for concentration, distillation, and recovery of organic solvents from feed liquids; The heating chamber is a rising film tube heat exchanger, and the entire system operates under negative pressure, so it will not damage the effective components of heat sensitive materials. It has the characteristics of high production capacity, high efficiency, and short heating time for materials. The contact parts between this equipment and materials are made of high-quality OCr18Ni9 stainless steel, which has good corrosion resistance, durability, and meets the requirements of pharmaceutical hygiene.