Patent ID: 7525664

Claim:
A device for the optical detection of substances contained in exhaust gases of chemical processes, the device comprising: a channel element forming an optical measuring section and through which the exhaust gases are conducted; two flanges closed off to an ambient area and disposed at opposing ends of the channel element, wherein a first of the two flanges opens into a bottom area of an interior of the channel element and a second of the two flanges opens into a top area of an interior of the channel element; at least one window element connected to each flange; and an optical detector, wherein electromagnetic radiation is directed from a radiation source to the optical detector through the flanges at the opposing ends of the channel element, through the at least one respective window element for each flange, and through the channel element in a gradient angle inclined with respect to a horizontal reference for the optical detection of the substances and with respect to a longitudinal axis of the channel element, from above to below, and a purge gas flows into the channel element through the flanges, and wherein one of the flanges is arranged in a zone of entry of the exhaust gas into the channel element and leads into the bottom area of the interior of the channel element in such a way that the purge gas exiting from the one of the flanges flows into a flow direction of the exhaust gas into the channel element and that, with the purge gas fed into the one of the flanges and exiting from the one of the flanges, a closed laminar purge gas flow is formed in the bottom area of the interior of the channel element and in the flow direction of the exhaust gas.