Carbon Dioxide → Sulfate Ion

Participants

Reaction Steps

Another embodiment is depicted in FIG. 3 wherein the present invention is adapted to the so-called "double alkali" stack gas scrubbing system. In this alternative embodiment, a slurry 8 of finely-ground limestone is prepared in tank 10 and fed to a reactor 12 wherein it is reacted with carbon dioxide at a pressure of about 500 psig to form a pressurized slurry 9. The pressurized slurry is then introduced into a solution regenerator 14 wherein the relatively soluble unstable calcium compound readily reacts with a sodium sulfite or sulfate solution 2 exiting a stack gas scrubber 16 to form a slurry 3 containing calcium sulfite or sulfate solids and sodium bicarbonate in solution. The slurry 3 is then depressurized into let-down tank 18 and then introduced into filter 20 for removal of the calcium sulfite or sulfate solids. Alternatively, the calcium sulfite or sulfate solids may be separated from the sodium bicarbonate solution in regenerator 14. Then the solution may be depressurized into let-down tank 18. The filtered solution 5 is then heated by solution heater 22 and further depressurized in tank 24 to convert the sodium bicarbonate to sodium carbonate in solution 6 which is used to scrub the stack gas in tower 16.

Provenance & Evidence