Design and economic analysis of membrane-assisted crystallization processes

Reverse-osmosis (RO) and porous hydrophobic membranes have attracted attention as an alternative to conventional evaporation for crystallization processes, the latter being recommended especially if low-grade waste heat is available to provide the enthalpy of vaporization. In this work, these two types of membrane-assisted processes are designed and costs are compared with those of conventional single or multiple-effect vacuum evaporation processes. When waste heat is not available, RO processes are shown to be the least expensive because the pumping costs, while significant, are more than offset by the fact that it is not necessary to provide the enthalpy of vaporization of the solvent. When waste heat is available, a conventional evaporation process is favorable because it can also be powered by the waste heat and does not require the capital cost for the membranes. ? 2017 Taiwan Institute of Chemical Engineers