Operation Principle and Process Analysis of Short-path Molecular Distillation Equipment

As the liquid mixture flows along the heating plate and is heated, light and heavy molecules escape from the liquid surface into the gas phase due to their different mean free paths. Consequently, the molecules of different substances move different distances after escaping from the liquid surface. By appropriately setting up a condenser plate, light molecules can reach the condenser and be condensed out, while heavy molecules fail to reach the condenser and are carried out along with the mixture.

Material is added to the **inlet** of the short-path molecular distillation unit, where it is continuously and uniformly distributed over the heating surface by the liquid distributor on the rotor. The scraper then spreads the liquid into a thin, turbulent film, which is spirally pushed downward. During this process, light molecules escaping from the heating surface condense into liquid on the built-in condenser through a short path and with minimal collision, flowing down along the condenser tubes and exiting through the discharge pipe at the bottom; the residual liquid, which consists of heavier molecules, is collected in the circular channel below the heating zone and then flows out through the discharge pipe on the side.

The water temperature inside the short-path molecular distillation unit will rise, affecting the vacuum level. By connecting the drain hose to the water source and using the overflow nozzle as the drainage outlet, and by controlling the flow rate of tap water appropriately, the water temperature in the reservoir can be maintained stable, thus ensuring the vacuum level remains steady. Since the evaporating molecules are much heavier than air molecules and mostly have the same direction of motion, their self-collision has little effect on the flying direction and evaporation rate. The liquid feed is evenly distributed on the heating surface by the feed liquid distributor on the rotor, followed by a scraper that forms a thin, turbulent liquid film and then pushes it downward in a spiral manner.

During this process, light molecules escaping from the heating surface condense into liquid on the built-in condenser through short paths and with minimal collisions, then flow down the condenser tubes and are discharged through the outlet pipe at the bottom of the evaporator. The residual liquid, which consists of heavier molecules, is collected in the circular channel below the heating area and then drained out through the side outlet pipe.