Distillieries - Environmental Clearance

DistilleriesSince the reaction is exothermic and proper growth of yeast requires a narrow temperaturerange, water is sprayed on the outer walls of the fermentation tank to maintain thetemperature between 25°C and 32°C.Fermented beer – the main product of this step is decanted and the remaining sludgeknown as fermenter sludge is discharged from the bottom of the fermenters. The sludgeamounts to about 300 to 400 litres (l) per kilolitre (kL) of rectified spirit produced, and isone of the major contributors to the pollution load from distilleries.DistillationThe fermented beer from the fermenter vessel is preheated to about 90°C by heatexchange with the spent wash flow from the analyzer column and is then fed into thedegasifying section of the analyzer column. Low boiling content of the fermented beersuch as organic acids, esters and aldehydes along with some alcohol vapours arecondensed in the aldehyde condensers. Purified wash from the bottom of the degasifyingsection enters the top of the analyzer column for steam stripping of alcohol whichcondenses at the top of the column as 40% alcohol. The down coming discharge fromthis column is spent wash.The 40% alcohol stream from the top of the analyzer column is next fed to the bottom ofthe rectification column where it is maintained at a temperature of about 95° to 100°C.Water and alcohol vapour condense at different levels in this column and rectified spiritof an equilibrium boiling composition (95%) is withdrawn. Of this rectified spirit, a partis fed back into the column. Spent lees, produced at this step are usually pumped back tothe analyzer column. The volume of spent lees is about 1-1.5 kL/kL of rectified spiritproduced.Figure 3-3: Process Block Diagram of Distillery (Molasses Based)TGM for Distillery Industry 3-15 August 2010