NEW PROCESS GAS ANALYZER FOR THE MEASUREMENT OF WATER VAPOR CONCENTRATION

摘要

A new analyzer for the measurement of water vapor concentration based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) was developed. The water-vapor line at 1854-nm was selected for the measurement, and the performance of the system was evaluated on different background gases to confirm that the measurement was free of interferences. An original feature of the instrument design is the use of an all-digital protocol for the modulation of the laser drive signal and the demodulation of the detector response. This innovation provides a simple means of varying the type of modulation protocol and all associated instrumental parameters. A reference cell is used in parallel with the sample cell to continuously validate the performance of the system. A limit of detection (LOD) of 5 ppmv and a range of 5 to 2500 ppmv were demonstrated.