Energy efficient vortex-enhanced water evaporation technology for concentrated brine management: Theory and process simulation evaluation

Abstract

Desalination drinking water systems and industrial processes generating high salinity streams require practical brine management options for disposal and/or treatment. Treatment most often involves large capacity brine concentrating processes, on the order of 2000 m3/day, that rely on water evaporation, vapor compression, and condensation. A new technology adds an aerosol-generating device to the evaporation step with the goal of energy efficient operation even at smaller scales. The principles behind the tornadic flowfield that breaks up and aerosolizes water as air and water flow over the machined surface in the device are introduced. Design of a 6.8 m3/day demonstration system, based on this new technology, producing a NaCl slurry (55 wt% solids) from a 22 wt% NaCl influent is described. Simulations of the system with three influent brine concentrations and three forms of final NaCl concentrate are presented and predicted energy usage is compared to estimates for conventional systems. By varying simulation process parameters, the heat transfer performance of the evaporator/condenser is identified as having a large impact on overall efficiency. The new system is anticipated to be most competitive, on an energy usage basis, with conventional concentrator/crystallizer systems when processing higher salinity brines and producing final concentrates containing precipitated NaCl.