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Photoacoustic system for process monitoring of water vapor concentration in natural gas
From processing technologies to natural gas flow in the export gas pipeline, the quality of the natural gas has to be strictly regulated and controlled. There are standards which set the maximum allowable water vapor and hydrogen sulfide concentration for commercialized natural gas. To meet the standards for the commercialized natural gas it has to be continuously processed and measured. To eliminate the deficiencies of the measuring instruments presently used in the gas industry we have developed a diode laser based photoacoustic system for hydrogen sulfide and water vapor concentration measurement in natural gas. The photoacoustic method is one of the simplest optical methods. It doesn't need to use precise and difficult optical systems, it can be easily automated.
The photoacoustic system enables the use of small sample volumes (few cm3). This simple method has high sensitivity, suitable for detection several gases at ppm or ppb level. Like other optical methods, photoacoustics has high selectivity and specificity. The method has a uniquely wide dynamic range; through five to six orders of magnitude the photoacoustic signal depends linearly on the concentration of the measured gases. As a result, a photoacoustic instrument is able to follow quick and large concentration fluctuations or small changes of high concentrations.
We have developed and deployed two photoacoustic measuring systems (WaSul) at two different gas processing plants. The results of their operation demonstrate the high reliability of these systems. The WaSul systems are commercially available from Hilase Ltd.
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Our manuscript is accepted for Infrared Physics and Technology
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