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:
Apr. 10, 1979
Filed:
Oct. 03, 1977
Volker Fattinger, Arlesheim, CH;
Ciba-Geigy Corporation, Ardsley, NY (US);
Abstract
A process is described for separating SO.sub.2 from a moist current of gas containing the same, at least intermittently, in a concentration which is impermissibly high for discharge into the ambient atmosphere, with attendant production of a strong sulfuric acid by the nitrogen oxide process in a system of reaction zones, in which system the SO.sub.2 -containing gas flows successively through a denitration zone, thereafter through the SO.sub.2 -processing zone, and subsequently through a nitrogen oxide absorption zone, in the course of which flow it is brought into contact, at least in the SO.sub.2 -processing zone, with dilute acid having an H.sub.2 SO.sub.4 -concentration of less than 70% by weight and flowing in a cycle through the latter zone, and wherein said nitrose containing acid is indirectly heated, prior to its introduction into said denitration zone to a sufficient temperature for freeing the latter acid substantially completely from nitrogen-oxygen compound, whereby the acid leaving said denitration zone has an H.sub.2 SO.sub.4 -content of at least about 75% by weight, thus being withdrawable as product acid; wherein the nitrogen oxides withdrawn from the said nitrose-containing acid into the current of gas are absorbed by nitrose-free or nitrose-poor sulfuric acid having an H.sub.2 SO.sub.4 -concentration between 70 and 85% by weight, from said denitration zone; and bringing a moist current of said SO.sub.2 -containing gas in a pretreatment zone upstream of said denitration zone into contact with a portion of said dilute sulfuric acid removed from the circulation through said SO.sub.2 -processing zone and passed into the pretreatment zone, the resulting acid more diluted by moisture from said gas being reintroduced into said circulation, thereby diluting the sulfuric acid formed in the SO.sub.2 -processing zone, this portion of the moisture content of the SO.sub.2 -containing gas thus bypassing the gas flowpath leading to the denitration zone.