Have you seen the differences? 712-HOUR GAS

摘要

Case 72-9818+ Canada Process for separating SO2 from a current of gas, with production of sulphuric acid by the nitric oxide process A process for separating SO2 from a current of gas, with production of sulphuric acid by the nitric oxide process in a tower system is described, in which the SO2-containing gas is introduced into a denitration zone and, after passing through the latter at a nitric oxide concentration of at least 1 % by volume in the gas phase,onward into an SO2-processing zone comprising at least one packed tower, in which it is brought into intimate contact with sulphuric acid containing less than 70 % by weight of H2SO4 (dilute acid, the acid being used to absorb the nitrogen oxides in the towers downstream from the SO2-processing zone having a concentration of between 70 and 85 % by weight of H2SO4 (absorption acid): this process is improved bya) heating the nitrose-containing acid intended for the denitration zone which, relative to the direction of gas flow, is located upstream from the first tower, trickle-fed with dilute acid, of the SO2-processing zone, by indirect heat exchange to above 60.degree.C before it comes into contact with the gas stream which leaves the denitration zone, andb) holding the sojourn time of the gas between leaving the denitration zone and entering the first tower of the nitric oxide absorption zone, at concentrations of at least S % by volume o SO2 and at least 10 V/o by volume of .degree.2 in the gas entering the denitration zone, at less than 30 seconds, and, at lower SO2 contents or lower O2 contents in the said entry gas, limiting the residence time to a maximum length calculated from the equation in which formula Zmax is the sojourn time in seconds, ¢SO2! denotes the SO2 content in the gas entering the denitration zone, in % by volume, and ¢O2! denotes the oxygen content in the same entry gas, in % by volume.