Manufacturing of Rectified Spirit
The yeast is initially propagated in the propagation vessels and then transferred to the fermenter. Molasses diluted with water to the desired concentration is metered continuously in to a fermenter. Spent wash from distillations recirculated to fermenter depending on solids concentration in fermented wash and molasses composition. During fermentation process yeast cells convert sugar in to alcohol. Fermentation is an exothermic reaction, heat is evolved during the fermentation and it is continuously cooled by plate type heat exchanger.
Temperature is maintained between 32-350 C. Small quantities of Urea and DAP are added in the fermentor as nutrients to the yeast cells. Viable yeast cell population of 300- 400 million cells/ml is maintained in the fermentor by continuous aeration and yeast recycling.
The fermented wash passes through series of hydro cyclones which removes grit, iron filling and heavy particulate matter. The material settled at the bottom of the hydro cyclone is fed to the bottom of the analyser column to strip the alcohol present in it. The overflow from the hydro cyclone is fed to the yeast separators. Yeast cream is recycled back to the fermenter to maintain the yeast cell population. De yeasted wash is stored up in prop III vessels.
The wash is preheated to 85 – 90oC in the bear heater, plate type mash heater and spent wash cooler and it is fed to the top of degasifying column. Fermented wash is stripped off alcohol by ascending vapours in Analyser column. Rectifier vapours provide energy to analyzer column through a Thermosyphon reboiler. Vapours of degasifying column are condensed and taken to pre Rectifier Feed Tank.
Analyser vapours are condensed in Evaporation section. The condensed analyzer vapours are taken to Pre Rectifier Feed Tank. Rectifier Column, which operates under pressure, concentrates the condensate of analyzer column to 95% v/v concentration. Condensing steam provides energy to pre rectifier column through a vertical Thermosyphon reboiler. Fuse oil draws are taken from appropriate trays and fed to FO decanter. An impure spirit cut of about 3 – 5 % of the total spirit production is taken out from the top of the pre rectifier column. Rectified spirit draw of 95% v/v is taken out from the upper trays of pre rectifier column.