Low‐voltage and ion‐free‐reverse‐migration electrically regenerated mixed‐bed ion exchange for MEG desalination

Abstract

An improved electrical regeneration method of ion exchange was proposed to enhance the feasibility of applying ion exchange for mono-ethylene glycol (MEG) desalination and simplify the existing MEG regeneration process in deepwater gas fields. Compared with the latest electrical regeneration process named membrane-free electrodeionization (MFEDI), this method required lower voltage, did not consume high purity water, and eliminated ion backward migration in principle. These improvements were achieved by changing the electric field direction and the flow direction from parallel in MFEDI to perpendicular during ion exchange regeneration step. In this work, a pair of commercial ruthenium oxide-coated titanium electrodes was installed on both sides of the cuboid experimental setup. The mixed resins consisting of strong-base and weak-acid resins were filled between the electrodes. In water flow and direct current electric field, the resins were regenerated successfully. The feasibility of efficient regeneration with high conductivity feed water (3-200 μS/cm) was verified. After regeneration of the resin bed for 1 h at a voltage lower than 73 V, 33.83% of NaCl in 5.16 bed volume (BV) simulated rich MEG liquid was removed. After 15 cycles of repeated operation, the performance of the resins remained stable. These results provide the possibility to reclaim MEG in deepwater gas fields through a simpler method.

Regeneration and Reclamation of Mono-Ethylene Glycol (MEG) Used as a Hydrate Inhibitor: A Review

“…This patent presented a system to remove divalent cations from rich MEG using a cation exchange resin that adsorbs the divalent cations in the rich MEG prior to its entry into a flash separator [41,42]. In 2020, He S. et al, published their work on an electrically regenerated mixed bed ion exchange resin for MEG desalination [43]. Ion exchange for MEG desalination is claimed to be less energy intensive compared to the volatility-based desalination by heating under vacuum.…”

“…The result indicated that the electrically regenerated mixed-bed ion exchange could be a promising prospect for MEG desalination in deep-water gas field operations. In recent times, research has shown a successful application of an ion exchange technology for MEG desalination [43]. The technical challenge as of today is the development of efficient regeneration of the ion exchange resin used for the MEG desalination.…”