| 摘要 |
The invention relates to a process for the dehydration of lower aliphatic alcohols, preferably ethanol, in which the top product formed during an entraining agent rectification is used for heating the dehydration column by means of vapour compression. On elevated pressure operation of the dehydration column, methylcyclohexane as the entraining agent causes, depending on the reflux ratio and plate number, a high water content of the ternary mixture ethanol/water/methylcyclohexane formed at the top, a favourable ratio of water:ethanol in this mixture and a top boiling point approximately equal to the bottom boiling point. Owing to the improved water content, the amount of the ternary mixture to be removed is reduced, while the ratio water:ethanol together with the water and ethanol concentration of the aqueous phase which is to be influenced by the temperature during the phase separation is favourable for the amount of ethanol flowing back from the processing column to the dehydration column. The low temperature difference enables energy-saving use of a vapour compressor. The total energy need can be reduced to 25% of the conventional value for two-column dehydration plants, consisting of dehydration column and processing column. A requirement is the use of the entraining agent methylcyclohexane. |
