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Regenerative recovery of sulfur dioxide from effluent gases

  • US 10,272,380 B2
  • Filed: 10/28/2011
  • Issued: 04/30/2019
  • Est. Priority Date: 10/29/2010
  • Status: Active Grant
First Claim
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1. A process for selectively removing and recovering sulfur dioxide from a sulfur dioxide-containing effluent gas, comprising:

  • contacting the effluent gas comprising the effluent gas and oxygen with a buffered aqueous absorption solution comprising a salt of a polyprotic carboxylic acid and an oxidation inhibitor selected from the group consisting of ascorbic acid, ethylenediaminetetraacetic acid, p-phenylenediamine, hydroquinone and mixtures thereof in a sulfur dioxide absorber, thereby absorbing sulfur dioxide from the effluent gas into the absorption solution and producing an exhaust gas from which sulfur dioxide has been removed and a sulfur dioxide-enriched absorption solution;

    heating the sulfur dioxide-enriched absorption solution in a sulfur dioxide stripper to desorb sulfur dioxide and thereby produce a regenerated sulfur dioxide absorption solution and a sulfur dioxide-enriched stripper gas; and

    reintroducing the regenerated sulfur dioxide absorption solution to the sulfur dioxide absorber;

    immediately following the step of heating the sulfur dioxide-enriched absorption solution in the sulfur dioxide stripper producing the regenerated sulfur dioxide absorption solution and the sulfur dioxide-enriched stripper gas comprising water vapor and before reintroducing the regenerated sulfur dioxide absorption solution to the sulfur dioxide absorber, the process further comprises;

    increasing the pressure of the sulfur dioxide-enriched stripper gas;

    cooling the pressurized sulfur dioxide-enriched stripper gas by transfer of heat to the regenerated sulfur dioxide absorption solution in a reboiler of the sulfur dioxide stripper to condense water vapor and produce a reboiler gas effluent comprising sulfur dioxide and water vapor and an aqueous condensate comprising sulfur dioxide;

    heating the aqueous condensate from the reboiler in a condensate stripper to desorb sulfur dioxide and produce a condensate stripper gas comprising water vapor and sulfur dioxide desorbed from the aqueous condensate; and

    cooling the condensate stripper gas and reboiler gas effluent in a low temperature condenser to condense water vapor and produce a recovered sulfur dioxide stream comprising sulfur dioxide obtained in the aqueous condensate and in the reboiler gas effluent and a stripped condensate effluent depleted in sulfur dioxide.

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