Electrodialysis device for the desalination of water for oil and gas applications

An electrodialysis device for desalination of water in an oil and gas environment, the electrodialysis device comprising:

• a membrane stack comprising alternating cation- and anion-exchange membranes;
• and
• a plurality of spacers, each spacer being arranged between two successive membranes and having a thickness;
• wherein at least one of the spacers comprises a recessed area and a non-recessed area, the non-recessed area surrounding the recessed area,
• and wherein:
• the spacer comprises a central opening within the recessed area, wherein the central opening has a peripheral edge;
• the spacer is provided with at least four orifices within the non-recessed area;
• the spacer is provided with respective channels extending from at least two of the orifices to the peripheral edge of the central opening, each channel comprising (i) a first portion located in the recessed area and extending to the peripheral edge of the central opening and (ii) a second portion located in the non-recessed area;
• and
• a cation-exchange or anion-exchange membrane is accommodated in the recessed area;
• wherein the entire first portion of each channel runs through the entire thickness of the spacer, and the entire second portion of each channel runs through only part of the thickness of the spacer.