Continuous gas analyser, especially for sulphur di:oxide

摘要

Continuous gas analyser has a detector (4a) for a target gas component and a device (10) for adjusting the humidity of the sample gas to a constant value. Sources of zero (16) and span (18) calibration gases (containing zero or a known concentration of the target gas component) can be connected to the sample gas inlet passage at a point (12) between the constant humidity device (10) and the detector (4a). Atmospheric air can be introduced through an inlet (44) upstream of the constant humidity device (10). The calibration curve memory of a data processor stores measurements from the zero and span gases measured in a dry condition as calibration data. The data processor includes a humidity correction computation part to subtract a measurement from the atmospheric air as a value of humidity from the measured value in the sample gas, and the computing part of the data processor calculates the concentration of the target gas component by applying the calibration curve data to a measurement which has been obtained by correction for the humidity disturbance.