Liquid ethanol vaporization into molecular sieve dehydration process

The liquid ethanol with a concentration of 95 %vol is first preheated by the preheater, and then enters the evaporator through the steam heater. The ethanol vapor generated by evaporation is superheated by the steam superheater and then enters the molecular sieve A tower. When the water molecules in the ethanol vapor flow through the molecular sieve packing layer, because the micropores of the molecular sieve have a strong affinity for the water molecules, the water molecules are adsorbed in the micropores, and the ethanol vapor after the adsorption is condensed and cooled to obtain the concentration more than 99.5% vol absolute ethanol. When the adsorption of the molecular sieve A tower is close to saturation, it will automatically switch to the molecular sieve B tower feed adsorption, and at this time the molecular sieve A tower will enter the desorption process. A part of the gaseous absolute ethanol after adsorption and dehydration in the molecular sieve tower B is heated up to serve as the regeneration carrier of the molecular sieve. Under the condition of high temperature and low pressure, ethanol gas is used to backwash the molecular sieve A tower to remove the moisture in the molecular sieve. The regenerated alcohol vapor is condensed in two stages, and the condensed light alcohol is returned to the distillation tower. The non-condensable gas is discharged by the vacuum pump to complete the molecular sieve A. Tower desorption process. The two molecular sieve adsorption towers alternately perform adsorption and desorption for recycling.

This process can increase the adsorption pressure of the molecular sieve by steam heating the liquid phase ethanol vaporization. According to the adsorption principle and characteristics of the molecular sieve, the increase of the adsorption pressure is beneficial to the adsorption capacity of the adsorbent and the adsorption selectivity of the adsorbent to ethanol and water. Under the same loading capacity of adsorbent, the higher the adsorption pressure, the greater the adsorption capacity. Therefore, this process is suitable for high-pressure adsorption to produce anhydrous ethanol above 99.9%vol. In the high-pressure adsorption process, the adsorbed anhydrous ethanol alcohol vapor can be used to preheat the liquid-phase ethanol. In addition, the liquid alcohol condensed during the pressure relief period and the vacuum backwash period during the desorption process is collected separately, and the high-concentration alcohol is returned to the reflux tank of the rectification tower, and the low-concentration alcohol is returned to the crude wine tank, which can reduce the steam consumption in the distillation process.