Applications and Perspectives of Ultrasonic Multi-Gas Analysis with Simultaneous Flowmetry

Gregory Hallewell (1) , John Dingley , Martin M. Doubek , Robin Feuillassier (1) , Sergey S. Katunin , Koichi K. Nagai , David D. Robinson , Alexandre Rozanov (1) , D Williams , Vaclav V. Vacek

1 CPPM - Centre de Physique des Particules de Marseille

We have developed ultrasonic instrumentation to simultaneously monitor flow and composition in a variety of gas mixtures. Continuous, real-time precision measurements of the relative concentration of binary pairs of gases are required in many applications. The presence of other gases can however cause ambiguities in the measurement: a particular measured sound velocity can be the result of varying combinatorial concentrations of additional gases. We have developed an algorithm to compensate for known concentrations of additional gases, allowing the concentrations of a pair of gases of primary interest to be measured on top of a varying baseline from other known components. This algorithm uses a thermodynamic data for the contaminant gases to “deduct“ their effects in multidimensional on-line databases. In our instrumentation flow and mixture composition are respectively derived from measurements of the difference and average of sound transit times in two opposite directions in a flowing process gas blend. Gas composition is then determined from an automated comparison of the measured sound velocities with a velocity/composition database of thermodynamic parameters for the gas pair of primary interest as well as for known third party gases whose concentrations in the multi-gas mixture are measured by other means. Several instruments are used in the CERN ATLAS experiment. Three monitor C3F8, (R218) and CO2 coolant leaks into N2-purged environmental envelopes. Precision in molar concentration of better than 2.10−5 is routinely seen in mixtures of C3F8 in N2 in the presence of varying known concentrations of CO2. Further instruments monitor air ingress and C3F8 vapour flow (at high massflows around 1.2 kgs-1) in a 60 kW thermosiphon C3F8 evaporative cooling recirculator. This instrumentation and analysis technique, targeting binary pairs of gases of interest in multi-gas mixtures, is promising for mixtures of anaesthetic gases, particularly in the developing area of xenon anaesthesia.

Mots clés: Ultrasonic Gas Mixture analysis; Ultrasonic flowmetry; Leak detection; Xenon anasethesia

Domaines: Acoustique [physics.class-ph]; Vibrations [physics.class-ph]

Gregory Hallewell, John Dingley, Martin M. Doubek, Robin Feuillassier, Sergey S. Katunin, et al.. Applications and Perspectives of Ultrasonic Multi-Gas Analysis with Simultaneous Flowmetry. Forum Acusticum, Dec 2020, Lyon, France. pp.3471-3472, ⟨10.48465/fa.2020.0040⟩. ⟨hal-03220562⟩