Method of removing nitrogen oxides from a gas and for converting same to ammonium sulfate
AssigneeKureha Kagaku Kogyo Kabushiki Kaisha
InventorsShigeru Saitoh, Tetsuya Watanabe, Koji Konno, Tadashi Nakamura
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Abstract
A method of removing nitrogen oxides from a gas containing nitrogen oxides and converting same to ammonium sulfate, wherein the gas containing nitrogen oxide is brought into contact with an aqueous solution which contains at least a ferrous salt and a sulfurous acid alkali salt to absorb the nitrogen oxides in the solution in the form of imidodisulfonic acid alkali salts, and the imidodisulfonic acid alkali salt is converted into ammonium sulfate by hydrolysis at a temperature higher than 100.degree. C after separation and recovery of the salt from solution.
Claims22
A method for removing nitrogen oxides from a gas mixture and converting same to ammonium sulfate comprising:
- contacting the gas mixture with an aqueous scrubbing solution containing at least 0.02% by weight of at least a ferrous salt and at least 0.2% by weight of a calcium or potassium salt of sulfurous acid to absorb the nitrogen oxides, thereby forming a calcium or potassium salt of imidodisulfonic acid;
- separating said salt of imidodisulfonic acid from solution;
- then
- hydrolyzing said imidodisulfonic acid salt at a temperature above 100.degree. C to form ammonium sulfate;
- and
- separating said ammonium sulfate from solution.
A method for removing nitrogen oxides from a gas mixture and converting same to ammonium sulfate comprising:
- contacting the gas mixture with an aqueous scrubbing solution containing at least 0.02% by weight of at least a ferrous salt and at least 0.2% by weight of an alkali salt of sulfurous acid, said alkali selected from the group consisting of lithium, sodium, magnesium, and ammonia to absorb the nitrogen oxides, thereby forming an alkali salt of imidodisulfonic acid;
- adding a calcium or potassium compound to the solution to convert the imidodisulfonic acid alkali salt to the corresponding potassium or calcium salt;
- separating said calcium or potassium salt of imidodisulfonic acid from solution;
- hydrolyzing said imidodisulfonic acid calcium or potassium salt at a temperature above 100.degree. C to form ammonium sulfate;
- and
- separating said ammonium sulfate from solution.
Dependencies are inferred from the claim text.