Canadian Journal of Chemical Engineering, Vol.89, No.5, 1255-1265, 2011
PROCESS ENERGY EFFICIENCY IN PERVAPORATIVE AND VACUUM MEMBRANE DISTILLATION SEPARATION OF 2,3-BUTANEDIOL
This work focused on the energy aspects of the pervaporative separation of 1-butanol/2,3-butanediol. A numeric model was developed to simulate the mass and energy balance of the pervaporation process. It was found that the distribution of evaporation heat requirement over the membrane area is asymmetric, and more than 85% of the heat was consumed in the 60% of the membrane area. It was also revealed that recycling the permeate having higher than 5% w/w 2,3-butanediol can improve the recovery of 2,3-butanediol, and thus enhance the process energy efficiency. Two recycling strategies (the single or multiple point admission of permeate to the retentate flow) were explored. The specific energy requirement (the heat required by generating 1 kg 99.5% w/w 2,3-butanediol as product) was proposed to evaluate the process energy efficiency of both the pervaporation and vacuum membrane distillation, and it was shown that pervaporation can bring about nearly four times energy savings over the vacuum membrane distillation.
Keywords:pervaporation;vacuum membrane distillation;process energy efficiency;numerical model;product recovery;permeate recycling