The process has the characteristic that, as alcohol vapor is boiled off from the beer, the concentration of alcohol in the beer becomes less and less. As the beer loses its alcohol content, the alcohol product also decreases in concentration. To prevent this, the reflux ratio must be raised.

Recall that higher reflux ratios usually mean higher proof. Raising the reflux ratio means getting less product from a given amount of vapor produced, hence a greater energy cost. When almost all the alcohol has been boiled out of the beer, the process is stopped and the spent stillage (formerly beer) is removed.

The basic advantage of this pot distillation process is its simplicity. It does not require a constant supply of beer, which is often not available in minimum-labor fuel alcohol processes. It also provides a very simple equipment system. with cooking, fermentation and boiling for distillation carried out in the same vessel. This procedure may aid in sterilizing equipment between successive batches, since cooking and fermenting in the same vessel tends to heat-sterilize. Separation of the spent grain and large solids from the beer prior to heating for distillation is not necessary, an added advantage.

It is possible to approach a continuous batching operation in a three-vessel, one-column pot system. A batch of grain would be cooked and fermented every 72 hours, with one batch ready for distillation every 24 hours.

The disadvantage of the pot distillation process and its system simplicity is lower distillation efficiency, because of the diminishing alcohol concentration in the beer under continuous boiling. Typically, a pot distillation unit requires about three times as much energy as an equivalent continuous distillation system, based on (by weight) feed 8 percent, stillage 0.4 percent and product 90 percent. Less stored heat may be used at the end of cooking when the slurry is rapidly cooled for fermentation; and heat losses during cooking and distillation heating cannot be minimized as readily as with the constant-feed process. Insulation applied to the pot to conserve heat during cooking and distillation heating may hinder cooling necessary to fermentation in the summer. Thus, amount of energy required per gallon of alcohol for the pot distillation process is high.