(396e) The Thermodynamics and Design of the Down-Stream Process of the Pervaporation With PDMS Composite Membranes

During a traditional membrane pervaporation process, in order to condense and capture the permeated vapors at the down-stream side of the membrane, a ‘cold trap’ unit at an extremely low temperature, e.g. -30°C, accomplished only with a refrigerating system, is needed, which takes a most part of the energy cost for the whole process. Based upon the thermodynamics of condensation and transportation of the vapors, a pervaporation process without a refrigerating system was designed, which can condense and capture the vapors at the normal temperature. In the procedure, a suction machine for the permeated vapor flowing, such as a vacuum pump or compressor was emphasized, and two condensers were set up at the inlet side and the outlet side of the machine, respectively. The condenser at the inlet side could be operated, by using the circulating water at the room temperature as the coolant, and the components with higher boiling point in the vapors could be condensed and collected here. The remaining vapors was discharged by the ‘compressor’ and condensed at the outlet side. The experiment was done for separating several organics-water mixtures in this new pervaporation system with a composite PDMS membrane. The system’s stability and the membrane separation characteristics were tested, which demonstrated its good performance. The feasibility and the energy consumption of the process were evaluated, which demonstrated that the designed process had a lower-energy-cost, less than 26% of the energy consumption compared with that in the traditional process.