What is a Column (Reflux) Still

Reflux is when the vapors liquify then falls back down.  That’s reflux.  Cooling tubes at the top of a column is not a Forced Reflux.  It is merely an internal condenser.  Forced Reflux is a term applied to a column that has multiple distilling stages of plates as detailed in another section.  A column distiller would be a forced reflux still if the collection of vapors for the condenser was after the cooling tubes. This type of design is not made.

Types: Unpacked and Packed

Unpacked Column Still: wide tube that rises up where reflux can occur in the column. Reflux is where the separation of the ethanol molecule from the water molecule occurs making the vapor more dense with the lighter ethanol vapor (alcohol) going into the condenser to be liquified.

Packed Column Still: This is where a portion of the column is packed with thin strands of copper mesh (also called scrubbers) so it will trap the bigger particles making them fall back into the heated mash Only very fine particles of the substance mash, along with alcohol molecules and water molecules are carried through the mesh out to the condenser.

UNPACKED COLUMN ——————————-

As the vapor climbs up the column (in a cyclonic spin) the heavier water drops off. The purity of alcohol varies depending on what level of the column the alcohol is at. The highest purity is at the top where it is then send to the condenser to liquify the steam vapor.

Diameter

The diameter of the column will also increase the volume and purity. A 3″ column will produce more pure alcohol than a 2″ column to the amount of 2.25 times more. You would need to increase a 2″ wide column that is 36 inches high to a height of 82 inches to get the same volume (nearly 7 feet). The ideal ration of column diameter to height is between 15 to 1 to 20 to 1. Above 20 to 1 requires more heat and operating costs. With a larger circumference there is more area for vapor to ascend. Measure the diameters times pi (3.1416) to compare the volume of vapor ascending between two diameters.

The coolness of the air around the column is important. Too little temperature change between the column inside temperature and the outside air will mean little reflux. This will mean a low distillate will be gathered.  Too much cooler outside temperature and the heat will have to be increased significantly to get the vapor to the top of the column.

PACKED COLUMN————————————

A Packed column intensifies the reflux action by 2 to 3 times what a straight empty column would do. Often called a reflux still. A reflux action is when the heavier condensation liquifies and falls back down the column to again be heated and becomes condensation again. The lighter steam containing alcohol and lighter particles continues past the packing. The mesh also helps keep the condensation off the walls of the column because the cooler air is around the insides of the walls.

Also the liquids with higher boiling points will fall because the temperature gets less as the height increases. The mesh is located in the lower portion of the column. Alcohol being the lightest and lowest boiling point will rise through the mesh.

The mesh is generally made of copper. The sulfur in the distillate reacts with the copper resulting in the copper sulfide in the vapor to remain on the copper. Only a small amount of copper is needed to have the copper sulfide attach. The copper needs to be cleaned after every distilling run.

COPPER MESH SCRUBBERS

MARBLES/GLASS BEADS

There are a few other variants to the copper mesh scrubbers; marbles and glass beads

RASCHIG RINGS

Having mesh in your column is the equivalent of having one plate on a forced reflux still.

The primary issue with such a design is that the lower portion of the tee fitting (where the condensate drips into) has a reservoir that holds the distillate to be collected. All rising vapor that reaches the top of the column will be condensed when it reaches the cooling coil, and that condensate will then drip into the reservoir. This means that even the vapor requiring further purification will be mixed with the other distillate in the reservoir, reducing the purity of the final distillate to at least some degree. This can be remedied by replacing the tee fitting with a 90-degree elbow so that this collection area is eliminated.