Carbon Dioxide → Bicarbonate Ion

Participants

Reaction Steps

While feed 41 to the bottom of the carbon dioxide absorber 50 is simply based on the desired hydrocarbon circulation rate in the reaction section, stream 62 is rich in potassium carbonate and is flow-controlled to the top of the tower 50. Guidelines are established for potassium carbonate and potassium bicarbonate concentrations in the carbon dioxide absorber bottoms stream 52 representative of proper operation of the carbon dioxide removal unit. For example, potassium carbonate content ranges from about 1 to 4 wt. % and potassium bicarbonate content ranges from about 20 to 25 wt. % in the absorber bottoms stream 52. Potassium acetate is an undesired byproduct in the removal process caused by carryover of vinyl acetate or acetic acid in upstream equipment. While this warning of carryover is valuable, the potassium acetate also inhibits absorption of carbon dioxide and is corrosive. For this reason, potassium acetate is typically blown down from the carbon dioxide absorber bottom stream 52 to keep its concentration below 4 wt. % in the stream 62. This also results in a loss of both potassium carbonate and bicarbonate. Potassium hydroxide is added to stream 62 to makeup for potassium lost as potassium acetate, carbonate and bicarbonate or as potassium metal compounds in the blowdown.

Provenance & Evidence