Gas analyzer for the measurement of nitrogen oxides and sulfur dioxide in exhaust gases

摘要

The exhaust gas (1) to be analyzed is passed untreated through a first measuring chamber (13) and after treatment in an oxidation device (23) through a second measuring chamber (16). In the oxidizer (23), ozone is generated from oxygen, preferably the residual oxygen of the exhaust gas (1), to thereby convert nitrogen oxide contained in the exhaust gas (1) into nitrogen dioxide. The gas analyzer has a first light-emitting diode (2) radiating between 350 nm and 500 nm and a second light-emitting diode (4) radiating between 250 nm and 300 nm, whose two lights (3, 5) pass through the first measuring chamber (13) to a first light-emitting diode Detector (14) is guided. A part of the light (3) of the first light-emitting diode (2) is directed by means of a beam splitter arrangement (10) through the second measuring chamber (16) onto a second detector (17). On the basis of the first detector signal (29), in addition to the sulfur dioxide concentration of the untreated exhaust gas (1) in the first measuring chamber (13) and its nitrogen dioxide concentration is measured. Based on the second detector signal (30), the nitrogen dioxide concentration of the treated exhaust gas (1) in the second measuring chamber (16) is measured. From both measured nitrogen dioxide concentrations, the nitrogen oxide concentration of the exhaust gas (1) is additionally determined.