The raw material that meets the requirements of membrane feeding enters the preheater and evaporator through the raw material pump, and enters the membrane separation unit in the form of steam after reaching a certain temperature. The membrane separation unit is composed of multiple membrane modules connected in series. The moisture and a small amount of organic matter in the raw material permeate from the upstream side of the membrane to the downstream side of the membrane through the membrane module, and the final stage of the upstream side of the membrane is used to obtain the finished product. The downstream side of the membrane adopts the method of vacuuming and condensing to form the vapor partial pressure difference between the upstream and downstream components of the membrane. The permeate vapor enters the condenser under the suction of the vacuum unit. The condensed permeate is discharged through the permeate pump and then recycled.