Harnessing dimethyl ether with ultra-low-grade heat for scaling-resistant brine concentration and fractional crystallization
Name
FOO_preprint_CEJ_Solvent_Extraction_2024.pdf
Description
Accepted version
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8.71 MB
Format
Adobe PDF
Checksum (MD5)
34d6028bf92603a5024b0f6ed0618679
Author(s)
Foo, Zi Hao
Deshmukh, Akshay
Wilson, Aaron D.
Lienhard, John H
Date Issued
June 2024
Journal
Chemical Engineering Journal
Publisher
Elsevier BV
Citation
Foo, Zi Hao, Deshmukh, Akshay, Wilson, Aaron D. and Lienhard, John H. 2024. "Harnessing dimethyl ether with ultra-low-grade heat for scaling-resistant brine concentration and fractional crystallization." Chemical Engineering Journal, 489.
Version
Author's final manuscript
Abstract
Solvent-driven separations may enable scalable concentration of hypersaline brines, supporting a circular resource economy from the extraction of lithium and rare earth elements from spent battery and magnet leachates. This work analyses a novel solvent-driven water extraction (SDWE) system employing dimethyl ether (DME) and ultra-low-grade heat for brine concentration and fractional crystallization. SDWE exploits DME’s unique properties: (1) a low dielectric constant that promotes water solubility over charged solutes by a factor of 10
, and (2) a high volatility that facilitate efficient DME reconcentration with ultra-low-grade heat. The techno-economic viability of SDWE is assessed with a computational framework that encompasses a liquid–liquid separator and a solvent concentrator. We integrate the extended universal quasichemical model with the virial equation of state to predict the compositions of the complex three-phase DME-water mixture at vapor–liquid and liquid–liquid equilibrium. Subsequently, we optimize the thermodynamic and economic performance of SDWE, by controlling the interstage flash pressure, heat source temperature, and the number of concentrating stages. DME-based SDWE concentrates an input saline feed to 5.5 M and regenerates over 99 % of the DME using ultra-low-grade heat below 50 °C, with a DME/water selectivity ratio of 125. Our calculations reveal that optimal performance is achieved at interstage flash pressures of 0.4 – 0.5 bar for heat source temperatures between 323–373 K, with improved exergetic efficiencies at lower temperatures. At a heat source temperature of 323 K and an interstage pressure of 0.489 bar, DME-driven SDWE achieves an optimal thermodynamic efficiency of 20.5 % and a projected specific cost of US$ 1.93 m−3. These specific costs suggest that SDWE is competitive with commercialized thermal distillation technologies, while mitigating the traditional risks associated with scaling in heat and mass exchangers with hypersaline brines.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Center for Computational Science and Engineering
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Creative Commons Attribution-Noncommercial-ShareAlike
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DOI of Published Version
https://doi.org/10.1016/j.cej.2024.151159
