CO2 quality control by scrubbing in oxy-fuel combustion prior to compression: Relating pH to the liquid composition from absorption of SO2 into sodium based solutions to identify an operational pH window

The operational pH of the sodium based quench units is recommended to be in region 2, where a high absorption rate of SO2 and low sodium loss are expected. An operational pH window is thereby defined in terms of upper and lower limits. The operational pH window is found to be related to the concentration of sodium solutions when an inlet concentration of SO2 is proximately 3000 ppm, and the window narrows at high concentrations of sodium solutions. The operational window is secondarily related with the concentrations of SO2 and narrows at low concentrations of SO2.