Downstream Pressure and Condensation Strategy

On the industrial scale, the vacuum pump is shut off once vacuum is established in the downstream circuit and ideally the condensahon unit alone maintains the vacuum. This procedure allows operahng in a more economical way allowing mini-mizahon of energy costs. 

The permeate vapor is typically recovered in condensers at a temperature that allows a quantitative condensation of the vapor. Condensation can optionally be carried out in a series of condensation stages, at different temperatures, in order to achieve a permeate fractionation and increased enrichment of target compounds. Because the condensation efficiency is determined by both the condenser temperature and the residence time of the permeate vapor in the condenser, careful design of the condensation unit becomes crucial. New ways of capturing the permeating vapors have been suggested in the literature but no successful application has been reported. The concept is attractive but the low molecular density of the vapor permeate does not favor its capture by adsorphve and/or absorptive techniques. 

The technical aspects outlined above illustrate that for a process optimization all process parameters must be considered, since they strongly affect each other. It should also be pointed out that although vapor permeation and pervaporahon are membrane separation process, their selectivity and effectiveness may be significantly determined by mass and heat transport phenomena occurring beyond the membrane surfaces. 

Implementation ofVapor Permeation/Pervaporation in Chemicai Processes 

Isopropanol, ethanol Standard applications for pervaporation, typically dehydrated from their azeotropes to fractions of a percent of water. De-bottlenecking of entrainer plants. 

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