The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 23, 1977
Filed:
May. 12, 1976
Kobe Steel, Limited, Kobe, JA;
Abstract
The present invention provides a method of converting NO.sub.3.sup.- ions which are contained in denitration waste liquids to nonpoisonous N.sub.2 gas or to valuable by-products. In the method of the invention, concentrated sulfuric acid is added to the waste liquid which results from denitration of exhaust gases which contains calcium nitrate and calcium chloride to obtain a mixed solution of nitric acid, hydrochloric acid, sulfuric acid and calcium sulfate. The ratio of the chloride ions to nitrate ions in the mixed solution is adjusted within the range of Cl.sup.- /NO.sub.3.sup.- = 2-3; the mixed solution is heated to 110.degree. to 150.degree. C after adjusting the concentration of sulfuric acid in the solution to 10 to 70% by weight to thereby convert the mixed solution to a mixed gas essentially including NOCl, Cl.sub.2 and nitrogen oxides. The mixed gas is then passed through concentrated sulfuric acid having a concentration higher than 80% which is maintained at a temperature of 80.degree. to 150.degree. C to obtain a nitrosylsulfuric acid solution. A mixed gas containing SO.sub.2 and H.sub.2 O is passed into the thusly formed nitrosylsulfuric acid solution to obtain a mixed gas containing NO, NO.sub.2 and SO.sub.2 which is then introduced into a reducing solution to convert the nitrogen oxides to N.sub.2 gas.