Co2 capture process with electrolytic regeneration

A system for scrubbing a gas, such as flue gas or exhaustive gas, comprising carbon dioxide to deplete the flue gas of carbon dioxide, the system comprising:

• a scrubber arrangement for scrubbing a gas with an alkaline, aqueous scrubbing liquid to dissolve carbon dioxide as hydrogen carbonate (HCO3−) and/or as carbonate (CO32−) in the alkaline, aqueous scrubbing liquid;
• and
• a regeneration arrangement for regenerating spent aqueous scrubbing liquid by electrolysis, wherein:
• the scrubber arrangement comprises a scrubber, the scrubber having an inlet for the gas to be scrubbed and an outlet for gas depleted of carbon dioxide, the scrubber further having an inlet for receiving the alkaline, aqueous scrubbing liquid and an outlet for withdrawing spent aqueous scrubbing liquid;
• and
• the regeneration arrangement comprises an electrolytic cell, comprising an anode chamber and a cathode camber separated by a membrane, the anode chamber comprising an anode inlet for receiving the spent aqueous scrubbing liquid and an anode outlet for withdrawing oxygen and carbon dioxide, and the cathode chamber comprising an outlet for withdrawing regenerated aqueous scrubbing liquid and hydrogen;
• wherein the outlet for spent aqueous scrubbing liquid of the scrubber is in flow communication with the inlet for the spent aqueous scrubbing liquid of the anode chamber, and the outlet for regenerated aqueous scrubbing liquid of the cathode chamber is flow communication with the inlet for the alkaline, aqueous scrubbing liquid of the scrubber.

A scrubber arrangement for scrubbing a gas, such as flue gas, comprising carbon dioxide to deplete the flue gas of carbon dioxide, the scrubber arrangement comprising a scrubber having an inlet for the gas to be scrubbed and an outlet for gas depleted of carbon dioxide, the scrubber further having an inlet for receiving the alkaline, aqueous scrubbing liquid and an outlet for withdrawing spent aqueous scrubbing liquid;

• wherein the scrubber arrangement comprises a first and a second buffer tank for alkaline, aqueous scrubbing liquid, and the scrubber comprises at least a first and a second absorber, wherein:
• the first absorber comprises an inlet for receiving alkaline, aqueous scrubbing liquid from the first buffer tank and an outlet for withdrawing spent aqueous scrubbing liquid and feed it to an inlet of the first buffer tank, whereby aqueous scrubbing liquid may be circulated between the first absorber and the first buffer tank;
• and
• the second absorber comprises an inlet for receiving alkaline, aqueous scrubbing liquid from the second buffer tank and an outlet for withdrawing spent aqueous scrubbing liquid from the second absorber to feed to an inlet of the second buffer tank, whereby aqueous scrubbing liquid may be circulated between the second absorber and the second buffer tank;
• wherein
• the outlet of the second absorber is in flow communication with the inlet of the first absorber.

A regeneration arrangement for regenerating a spent aqueous scrubbing liquid comprising hydrogen carbonate (HCO3−) and/or carbonate (CO32−) used in electrolysis to provide alkaline, aqueous scrubbing liquid, the regeneration arrangement comprising an electrolytic cell, comprising an anode chamber and a cathode chamber separated by a membrane, wherein the anode chamber comprises an anode inlet for receiving the spent aqueous scrubbing liquid and an anode outlet for withdrawing oxygen and carbon dioxide, and the cathode chamber comprises an outlet for withdrawing regenerated aqueous scrubbing liquid and hydrogen;

• wherein
• the regeneration arrangement further comprises a concentrator for concentrating an aqueous stream comprising some hydrogen carbonate (HCO3−) withdrawn from the anode chamber to provide a concentrated stream comprising hydrogen carbonate (HCO3−) and an aqueous stream depleted of hydrogen carbonate (HCO3−), the concentrator being in flow communication with the electrolytic cell such that:
• the aqueous stream comprising some hydrogen carbonate (HCO3−) may be withdrawn from the anode chamber and fed to the concentrator;
• the concentrated stream comprising hydrogen carbonate (HCO3−) may be withdrawn from the concentrator and fed to the anode chamber;
• and
• the aqueous stream depleted of hydrogen carbonate (HCO3−) may be withdrawn from the concentrator and fed to the cathode chamber;
• optionally the regeneration arrangement further comprises:
• a first balance tank for regenerated alkaline, aqueous scrubbing liquid, the first balance tank having a first inlet for receiving regenerated alkaline, aqueous scrubbing liquid, a second inlet for receiving the aqueous stream depleted of hydrogen carbonate (HCO3−) withdrawn from the concentrator, and an outlet for feeding diluted regenerated alkaline, aqueous scrubbing liquid to the cathode chamber of electrolytic cell;
• and/or
• a second balance tank for spent aqueous scrubbing liquid, the second balance tank having a first inlet for receiving spent aqueous scrubbing liquid from the scrubber arrangement, a second inlet for receiving the concentrated stream comprising hydrogen carbonate (HCO3−) from the concentrator, and an outlet for feeding spent aqueous scrubbing liquid to the anode chamber of electrolytic cell.