The feed liquid for the falling film evaporator is added from the top of the heating tube. Under the action of gravity, the solution flows downward in a membrane form along the inner wall of the pipe and is evaporated and concentrated. Vapor-liquid mixture enters the separation chamber from the bottom of the heating pipe. After gas-liquid separation, the liquid is discharged from the bottom of the separator.
Solvent handling is better than rotary evaporator. Crude oil mixed solvent after extraction is desolved in falling film evaporator and then crude oil is obtained.