Carbon dioxide purification from fermentation by cryogenic process and distillation process

Abstract

The aim of the study was to reduce on carbon dioxide emission arising from alcoholic fermentation processes that impact on human health and environment and also assess the relationship between temperature and pressure parameters during purification of carbon dioxide. This work was done at BDF distillery. Multi-stage compression, refrigeration, separation and distillation is cryogenic separation and distillation method that separated majority of the CO2 from the gas mixture with relatively high purity. Subsequently, the separated crude liquid CO2 is distilled under high pressure and near ambient temperature conditions so that low energy penalty purification is achieved. Initially gaseous mixture is stored in the carbon dioxide sack then initially dehydrated before they are fed into the system, compressed, and cooled down to near ambient temperature thus achieving the cryogenic separation and liquefaction processes where most of the water is condensed and can be extracted out afterwards, while the rest is absorbed by a high-efficiency adsorbent (molecular sieve). At this point, a part of the CO2 is liquefied from the mixed gases. Using a gas-liquid separator CO2 product is separated from gaseous mixtures of the purge gases. The crude liquid CO2 separated from the cryogenic separation subsystem is further purified in the distillation subsystem at temperatures –20 °C to 20 °C and –10°C to 30 °C, to improve its purity. A sample of liquefied carbon dioxide after distillation is taken to laboratory for purity test using carbon dioxide purity tester. Its purity range was between (99.2- 99.9) % with impurity (2% to 5 %.) content in the separated liqui