In recent years, the authorities in a number of countries have taken legislative measures against emissions of brewhouse vapours, partly because of concern about possible environmental damage, but largely because many members of the general public regard the odour of these vapours as offensive. The West German Clean Air Regulations of 1986, as well as dealing with atmospheric pollutants such as smoke and other combustion products, specifically mention emissions of offensive odours as subject to limitation. In these regulations, the suggestion is made that the carbon content of the vapours be used as a guide, as although the absolute level of hydrocarbons etc. in such vapours is not related to the strength of the odour, a major reduction in carbon compounds is almost always accompanied by a reduction in odour intensity. Experiments are described in which the carbon content of vapours given off during wort boiling at the Bavarian State Brewery, Weihenstephan, was continuously monitored by an on-line flame ionisation detector. The bulk of the vapour was condensed by means of a plate heat exchanger and the remainder piped into the furnace of the brewery boiler. The effects of varying combustion temperatures and proportions of brewhouse vapour on the composition of the flue gases were monitored. The carbon concentration of the flue gas ranged from 1 to 4 mg/cu m, whereas the vapour averaged 100 mg/cu m.
Keywords : boiler brewhouse carbon combustion emission flame ionisation hydrocarbon legislation odour wort boiling