Stephen L Moody

US Patent:

44928629, Jan 8, 1985

Filed:

Aug 7, 1981

Appl. No.:

6/290824

Inventors:

Jack Grynberg - Englewood CO
Leonard Y. Nelson - Seattle WA
Stephen E. Moody - Kirkland WA

Assignee:

Mathematical Sciences Northwest, Inc. - Bellevue WA

International Classification:

G01V 500

US Classification:

250255

Abstract:

Beams (11) and (13) produced by helium-neon gas lasers (10) and (12) are directed at photoacoustic absorption cells (20) and (21) containing a flowing sample gas stream recovered from coal, oil and natural gas well drilling. The common hydrocarbon gases and vapors within cell (20) highly absorb the infrared energy emitted by laser (10) thereby producing an acoustic disturbance which is detected by a transducer (34) which produces an electrical output signal proportional to the concentration of the hydrocarbon gases and vapors. The methane gas within cell (21) weakly absorbs the infrared energy of laser beam (13), and thus the resulting output signal produced by a transducer (35) serves as a reference signal for determining the methane concentration. The output signals from transducers (34) and (35) are used by data processing unit (40) to compute the total concentration of hydrocarbon gases and vapors and the concentration of methane gas within cells (20) and (21). A turnable carbon dioxide gas laser (44) produces laser beams (45) and (47) both in the infrared region which are highly absorbed by the propane and n-butane component gases, respectively, flowing through photoacoustic cell (48).