Distiller magazine

156 distiller ratio is not as large as with trays that have downcomers. In some older beer/wash columns, designers used bubble caps on the trays or tunnel trays, but the problem, espe- cially with a molasses wash, is extreme scaling. is still takes place on sieve trays, but they are much easier to clean. Molasses with a high calcium content can build up a scale that can be up to 2 cm thick in just two weeks, especially if high pressure steam is used to heat the column. Scaling is not a big issue with grain beer, but some scaling can occur because of the hard water used in the cooking process. A dilute caustic clean- ing is recommended on a regular basis. e three heat exchangers mentioned above are (a) a beer preheater that uses the exiting vapor to preheat the incom- ing beer, (b) a rectifying condenser that condenses vapor leaving the beer preheater and(c) a vent condenser that is run at a warm temperature to allow incondensable gases, methanol and some volatile components to vent off into the atmosphere through a flame arrester vent. e sizing of all three heat exchangers is crucial. e beer temperature leaving the preheater should be about the same temperature as the entry tray on the column; this determines the number of tubes in the preheater (the heating surface) in relation to the beer feed rate. Some claim that this reduces scaling in the column. Surfactants have been used to reduce scaling, but this is expensive and somewhat ineffectual. e rectifying condenser sizing is based on the water temperature for cooling and the amount of vapor that should go to the vent condenser, which produces the heads cut and the vapor expelled to atmosphere. e beer column produces, as above, a high wine with all the nonvolatile components that will be selectively removed in the following column or col- umns that redistill the high wine. e high wine contains most, if not all, the nonvolatiles and some of the volatiles that will travel to the other columns for further rectification. ese will produce anything from a flavorful distillate to a neutral spirit required for the production of vodka, gin or some liqueurs. e column still shown (Exhibit 2) has some rectifying trays to have the option of producing a viable product — e.g., bourbon at a maximum of 160 proof, a flavorful rum or a low-proof tequila. Bourbon can also be produced just using a stripping still with fewer trays and a thumper or doubler. is is a progression from the original method using the Irish system employing three pot stills. e hot effluent leaving the column — dunder (rum), vinasse (Spanish) or whole stillage (grain mashes) — can be used to preheat water for cooking or Exhibit 2

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