Homemade Pure-Ethanol Still
This compact home distillery is for producing nearly-pure ethanol for
renewable-liquid-fuel experiments. But be aware that ethanol alone has a 60 F
flash point compared to gasoline's -45 F, so it will be very hard to start an
engine using ethanol alone. A practical system would require a gasoline-mist
or engine-starter (ether) spray for starting.
The mash is heated in a glass carboy inside a hot-water bath. The carboy
takes the place of the copper pot of the still. Ethanol boils at 173.3 F and
water boils at 212 F, and this allows them to be separated. The water bath is
held at about 190 F, heated by a propane turkey-fryer burner. It takes less
than an hour for the water and 5 gallons of mash to reach 190 F.
The carboy and modified keg.
The carboy holds 5 gallons and the keg holds up to 16 gallons. The top of
the keg was cut out with a jigsaw using bimetal blades. The base plate of the
jigsaw was removed and the blade was oiled during cutting.
The thermometer and reflux column.
The digital thermometer (MSC #86491016) has a remote probe. The reflux
column is silver-brazed 26-ga. stainless steel 3 & 1/2" in diameter and 34"
high. Harris Safety-Silv45 and its flux was used. There is a 9/64" hole in
the top of the reflux column for the thermometer probe.
Copper scouring pads are used for the reflux column media. They are held
in by a slotted stainless steel disk silver-soldered into the bottom cone.
Any media needs to be solvent-cleaned and soapsuds-cleaned first.
Steam condenses on the media and returns to the carboy as water so that
only ethanol vapor goes over into the copper coil worm in the condenser.
A #10 stopper seals the gap between the reflux column and the carboy. The
hole in this stopper was enlarged to 1" so that the water can return freely.
There is a no. 8 1/2 stopper in the top of the reflux column for the 3/8" x
12 ft. long copper worm.
The condenser tank.
The annular ring condenser tank goes around the reflux column and is filled
with ice. It is made of galvanized sheet metal sealed with acid-core solder.
The central core is 5" in diameter and 18" high. The outer tube is 10" in
diameter and 16 & 1/2" high. Ethanol vapor must be cooled to below 60 F to
condense. So if there is any ice at all is in the tank, it will condense.
The complete still.
The turkey fryer burner is in a metal plate on the ground. The carboy sits
on a 3" high aluminum riser inside the keg. Two cups of salt are added to the
water to raise the boiling point. The probe of the thermometer was in the hot
water bath at first. It was moved to the top of the reflux column after the
hot water bath is 195 F and holding steady. Later a second thermometer was
used for the hot water bath so that both could be monitored together.
The specific gravity of the final product should be .789 for pure ethanol.
A hydrometer in this range is MSC #56498017. The closer the temperature is
held to 173.5 F, the purer the ethanol will be. When the last of the ethanol
has boiled over and condensed, the dripping from the worm will stop.
The hydrometer and sample ethanol.
This 150-proof grain alcohol was used for ethanol comparison. The
hydrometer floats high in it, right at the shoulder of the wide bottom part
and out of range of the calibrations, which are from .700 to .810. Later, a
proof-marked hydrometer was purchased for checking lower concentrations.
It was found necessary to insulate the reflux column from the very cold
condenser using pipe insulation. And since some vapor leakage occurred at the
stopper between the reflux and the carboy, a 5-lb. barbell weight was put on
the reflux to stop it.