457239 Intensification of Batch-Distillation Processes for Production of Alcoholic Beverages

Wednesday, November 16, 2016: 2:30 PM
Union Square 5 & 6 (Hilton San Francisco Union Square)
Peter Scheruebel, Peter Letonja and Matthaeus Siebenhofer, Institute of Chemical Engineering and Environmental Technology, Graz University of Technology, Graz, Austria

During production of alcoholic beverages, especially the alcoholic fermentation of pomaceous fruit, formation of methanol is an issue that has to be considered. Since the middle lamella which binds adjacent fruit cells, consists of methylated polygalacturonic acid, i.e. pectin, the formation of methanol is unavoidable during natural fruit specific enzymatic digestion. Furthermore pectin methyl esterase is commonly added to the fruit mash in order to gain an enhanced yield of ethanol. While methanol in principle is not toxic to human beings, the effect of metabolites formaldehyde and formic acid can cause severe injuries to health, e.g. blindness or acidosis and can even cause death. Thus the separation of methanol from distilled alcoholic beverages has to be explicitly taken into account.

Against the widely shared notion it is not possible to separate methanol by distillation using common batch distillation equipment, no matter if multi-stage columns or single-stage pot stills are used. Experimental investigations as well as dynamic simulations of single stage batch distillation with Aspen Hysys showed matching results. In fact methanol is distributed between foreshots, heart cut and tailings. Further the ratio of methanol to ethanol is increasing with cumulative distillation time. In addition high regulatory limits in the European Union for methanol concentrations in pomaceous fruit spirits of 1350 mg/100 ml pure ethanol compared to other spirits, e.g. wine brandies are often exceeded even though the high values are not set due to harmlessness to health but insufficient separation performance of standard batch distillation equipment. Hence the production of distilled pomaceous fruit spirits with less methanol content leads to the necessity of intensifying distillation processes with focus on new technical approaches.

The main goal of the current research is to improve the separation of methanol in the foreshots, using an extension of common lyne arms. For this purpose a pot still is equipped with an optional bypass which provides the possibility to route the vapor via an additional randomly packed lyne arm at the beginning of distillation to increase the separation efficiency. Further the bypass lyne arm enables enhancement of internal reflux, realized with a coaxial heat exchanger. In this manner methanol accumulates in the foreshots and may be separated from the heart cut sufficiently.


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See more of this Session: Innovation via Process Intensification
See more of this Group/Topical: Process Development Division