How Temperature Affects Alcohol Distillation
Temperature plays an essential part in distillation column operation. A higher temperature results in faster distillation rates, making cuts faster as well. Cuts allow you to distill down to your desired proof while simultaneously eliminating unwanted congeners from distillate.
At most distillers’ distillation runs, their goal is to increase proof without making cuts. To do this, alcohol must be vaporized at the correct temperatures; otherwise the azeotrope (the point at which distillation stops working) would move toward 100 percent and necessitate an increased reflux ratio and low pressure of less than 1/10 atmosphere.
Accomplishing these conditions is no simple task, and temperature is one of the key contributors. To understand its effect on distillation we can compare water’s and alcohol’s boiling points – water at 212 and 173 respectively.
Distillation involves heating a mixture of alcohol and water until it vaporizes, then collecting those vapors to form the distillate liquid that remains. Due to their different boiling points, vapors contain higher concentrations of alcohol than liquid.
Determine this concentration by plotting the composition of vapors versus that of liquid at each point in a column. As you move up, vapor composition approaches liquid composition, eventually reaching equilibrium at some point on the graph above; whereby alcohol concentration equals liquid concentration.