EDIT Heat exchangers are a classification of mechanical devices having many different forms, by which two fluids can be brought very close to each other in a manner so that some of the heat in the warmer fluid can quickly pass into the other. In a simple refining process example, a liquid chemical mixture in the bottom of a vertical cylindrical vessel (a tower) is brought to a slow boil by steam within tubes beneath the liquid surface. Some constituents in the liquid mix are low boilers - they boil at a relatively low temperature. These evaporate from the liquid first and the vapors go upward into an cooling section of the tower where those vapors are condensed by cold water flowing in tubes. That chemical condensate (distillate) is collected and stored as a refined liquid. As the mixture temperature is increased, the higher boilers are evaporated consecutively and are likewise condensed and collected. A moonshine still works the same way to produce ethynol as White Lightning alcholol. That refinery process is the one adapted to produce ethanol for fuel.
