Build a Vacuum-Pumped Home Distillery for Fuel Production

Using a vacuum pumped system, you can make an efficient home distillery to produce your own alcohol fuel.

| November/December 1981

Over the past several years, as many of you already know, there's been a tremendous amount of public interest in home-produced fuel alcohol, especially among people in the agricultural community. Unfortunately, a small-scale operation—such as that which might be set up by a handy individual with a limited budget—often isn't as time and energy efficient as are commercial plants simply because a backyard facility likely doesn't have the twin advantages of large capacity and state-of-the-art engineering.

As a result, the owner of an "appropriate"-sized fuel factory—though enjoying the satisfactions of lower initial plant cost and energy independence—might still have to "pay the piper" in terms of operating convenience and production expense. So, in an attempt to combine the desirable features of a homestead backyard still and an industrial behemoth, MOTHER EARTH NEWS researcher Clarence Goosen has spent the better part of a year designing and building a vacuum-pumped home distillery system to deliver a continuous flow of 185 proof ethanol at the lowest possible operating expense (see a diagram of this home distillery setup). 

Conventional Construction

In essence, the cost-conscious designer developed an efficient atmosphere still, which he then modified to incorporate a vacuum system. Thus the unit's "negative pressure" capability is an option that can be chosen or discarded by the builder. 

Clarence's still uses [1] a reboiler—heated by our multifuel hot-oil furnace (see Build a Hot Oil Wood Burning Furnace)—to serve as the "steaming vat" from which vapors rise, [2] a stripper column, filled with polypropylene pall rings, to remove the alcohol from the mash, [3] a rectifier column, also pall-ring packed, which further fractionates (that is, upgrades to a higher proof) the rising vapors, [4] a refluxing section (this assembly includes an internal heat exchanger and a high-proof-alcohol feed line) to keep the upper part of the rectifier at a constant temperature below that found in the lower section of the tube, and to provide a source of high-grade condensed ethanol that serves to enrich—and thus strengthen—the ascending vapors, and [5] a two-stage condenser column, which uses incoming mash and cold water, respectively, to remove the final product first from the driven vapor and then from the discharge air (that which is drawn through the vacuum pump). You'll notice, too, that the relatively compact design utilizes an interconnecting pipe—positioned between the stripper and the rectifier column—in order to halve the total height of the tower, which would otherwise be over 30 feet tall! 

How It Works

In operation, this newest version of the MOTHER EARTH NEWS distillery has proved to be quite effective, thanks to a combination of the vacuum system and several other desirable energy- and timesaving features. Briefly, here's how it works: Heat is constantly being added to the reboiler via an internal tubing network filled with hot oil. Because this chamber—along with all the other "sealed" components in the still—is under a vacuum of approximately 22 inches of mercury, the mash within the container will boil at only 125°F (this, of course, is due to the fact that the liquid requires less heat to come to a "roll" under a negative pressure condition). 

As the liquid boils, it gives off an alcohol-and-water vapor, which is driven up the stripper column where it loses its heat to fresh mash coming down the tube. This arrangement—it simply amounts to using mash rather than water as coolant in selected condensers—allows us to take advantage of the latent heat already contained in the rising mist to help vaporize the ethanol within the separately introduced mash mixture ... which will then move up the column with the reboiler-produced "steam."

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