Minimization of energy consumption for chemicals ultrapurification processes

Abstract

Semiconductor industry requires ultrapure chemicals to manufacture microelectronic devices. Hydrogen peroxide is one of the most demanded chemical by the semiconductor industry and ultrapurification processes are needed to achieve the electronic grade requirements for this chemical. Among all the ultrapurification alternatives, reverse osmosis emerges as the most desirable option according to environmentally friendly criteria. Through modelling based on membrane transport equations and mass balances, different integrated reverse osmosis membrane cascades have been previously optimized. All the optimal solutions were characterized by the maximum allowed values for the applied pressures in the reverse osmosis stages, corresponding to the highest energy consumption and the lowest energy productivity (expressed as economic profit of the process for each unit of energy consumed). In this work, the energy productivity of the process was maximized and the optimal operation conditions were those with minimum applied pressures. However, under those conditions the membrane area required increased and the membrane productivity (expressed as economic profit of the process for each unit of membrane area employed) decreased. Therefore, multi-objective optimization was formulated to maximize simultaneously the productivities of both resources (energy and membranes).