(626t) A Comprehensive Experimental Investigation On the Distillation Process of Chinese Liquor

Chinese liquor has been a traditional art continuing for thousands of years, but the distillation process has been less studied and the currently applied distillation operation still follows the way that it has been done in ancient time. In this work, systematic experiments were carried out in an industrial-scale distiller to investigate the effect of the operation conditions on the yield and quality of the liquor, and variation of liquor components during the distillation process. The steam flowrate of 1.60 kg/min gives the best yield and quality, suggesting there exists an optimal flowrate for the distillation. The lower steam flowrate can not provide the thermal condition for full evaporation of ethanol, while the higher flowrate causes the fermented grains to be pasted and hence increases the diffusion resistance. The yield and quality of the liquor obviously drop down with the increase of bulk density, implying that the fermented grains should be loosely packed. Both the yield and quality of the liquor are enhanced gradually with the increase of the bed height from 600 to 1250 mm, indicating that current distiller (commonly used bed height 700~900 mm) has great potential of improvement. Adding small amount of edible alcohol in the steam boiler (called cross-steaming technique) is proven to be helpful to increase the liquor yield, but excess amount of the addition causes the liquor quality degraded sharply. It is found that the liquor-vapor commonly leaks from the water block at the initial stage of distillation process and dramatically decreases the yield and quality of the liquor. The temporal pressure rise caused by the trapped air in the distillation system is mainly responsible for this leaking and a simple and effective method is proposed. The gas chromatography analysis results show that the variation of liquor components during the distillation process is closely related to their dissolving properties in ethanol/water. The findings provide important guidance for the improvement of distillation equipment and operation.