How a Reflux Still Produces Optimum Alcohol
Peggy Korth ©
Column: Column height and diameter are determined by the
amount of anticipated vapor and desired flow to maximize the distillation process for a specified quantity of beer. Beer is the fluid result of microbial and enzyme action on five and six carbon sugars that contains alcohol
produced during the fermentation of sugars.
distillation process is designed to separate water from alcohol within beer. The
percent of alcohol within any liquid is measured as ‘proof’. Pure
alcohol is measured as ‘200 Proof’ alcohol. Therefore percent and
proof are a multiple of 2.
the desired alcohol ‘proof’ or percent-of-alcohol also influences column parameters. When the beer is heated, hot vapors enter into the bottom of a distillation column passing through a selected
condenser. The selection of condensing materials depends on the amount of flow,
desired alcohol proof, and cost containment for the project. Condensing materials
can be either packing material or a plate system. Packing with marbles or copper
scrubbers is common in small stills. Larger stills use staggered plates which
maximize surface area that comes in contact with the rising hot beer. The beer
vapor condenses when it comes in contact with the physical impediment causing a separation of the alcohol and water. The heavier water rains back down into the bottom of the still. Packing in the lower
section of the still is referred to as ‘a stripper’ because it strips water from the alcohol.
re-evaporates the condensate leaving beer with a greater amount of water in the heated beer
container. Rising vapors continue to make a higher percentage of alcohol. Packing
and plates allow the separated condensate to be redistilled. Alcohol from a pot
still does not use packing or plates. In a reflux still the packing or plate
portion of the still is referred to as a rectifier.
Reflux: Reflux in a physical action on the hot alcohol
to cool the vapor and allow it to drip back into the lower level of beer. Because
the rectifier (scrubbers or plates) concentrates the alcohol or raises the proof as it travels up the column, the action of
reflux ‘concentrates’ or raises the ‘proof’ of the alcohol.
Two conditions elevate alcohol proof:
- Introducing cooling to the highest level of alcohol vapor
- Allowing the vapor to fall back into the heated beer thereby creating reflux.
the highest level or desired level of condensation is known as ‘equilibrium’.
the condensate within the column falls, the physical presence of the droplets removes water from the rising vapor due to the
hydrophilic nature of the alcohol molecule. However, heat allows the properties
of the lighter alcohol to continue to rise above the water-laden droplets thereby concentrating the proof or percent-of-alcohol
at the top of the still.
Temperature Control: Proper heating and valving control
alcohol vapor. To keep the alcohol at its highest percentage and lower the risk
of water passing through the alcohol outlet at the top of the still, the heat is adjusted for ideal alcohol vapor production. Proper valving controls temperature. A
valve adjusts the flow of rising vapor thereby controlling physical parameters of a still for size, construction materials,
or internal design factors. Using the exact boiling point of pure alcohol prevents
water from passing or rising above the condensation point because water requires a higher boiling temperature. A mixture of a lower-proof of alcohol has a greater water content.
The boiling point is related to the percent of alcohol and water. Therefore,
having the ideal temperature allows the highest concentration of alcohol to rise higher within the still. The liquid with ‘higher water content’ will condense at a lower part of the still and fall
down back into the beer.
Temperature and flooding: Temperature is most critical at the highest point in the still. Cooling causes alcohol vapor to condense first. If a large
quantity alcohol condenses due to a rapid lowering of temperature, the condensate overwhelms the system in mass and is referred
to as flooding. It is possible for
the entire vapor content to condense with a temperature drop and will empty all the vapor within the column. When this happens, distilling must start again. Proper insulation
assists in controlling temperature change. Ideally, the temperature is kept constant
when equilibrium is achieved.