Method for measuring the concentration of a gas component in a measuring gas

Patent metadata

Field	Value
Publication number	US-9709487-B2
Application number	US-201514601729-A
Country	US
Kind code	B2
Filing date	Jan 21, 2015
Priority date	Jan 22, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A method for measuring the concentration of a gas component in a measuring gas. An absorption line of the gas component is varied as a function of the wavelength of the light of a wavelength-tunable light source within a periodically sequential scanning interval. The absorption line of the gas component is modulated with a frequency (f 0 ). Modulated light is guided through the measuring gas onto a detector. A measurement signal generated by the detector is demodulated upon determining a harmonic (nf 0 ) of the frequency (f 0 ). A measurement result is produced by fitting a setpoint curve to the profile of the demodulated measurement signal. Both demodulated measurement signal and setpoint cure are filtered with the aid of the same filter function. The filter function is operative to suppress noise signal components of the demodulated measurement signal that disturb both signal components of the demodulated measurement signal and the setpoint curve.

First claim

The invention claimed is:

1. A method for measuring the concentration of a gas component in a measuring gas by a gas analyzer, the method comprising:
varying an absorption line of the gas component as a function of the wavelength of the light of a wavelength-tunable light source within a periodically sequential scanning interval;
modulating the absorption line of the gas component with a frequency (f 0 );
guiding the modulated light through the measuring gas onto a detector;
demodulating a measurement signal generated by the detector upon determining a harmonic (nf 0 ) of the frequency (f 0 ); and
producing a measurement result by fitting a setpoint curve to the profile of the demodulated measurement signal;
wherein both the demodulated measurement signal and the setpoint curve are filtered with the aid of the same filter function, the filter function being operative to suppress noise signal components of the demodulated measurement signal that disturb both signal components of the demodulated measurement signal and the setpoint curve.

2. The method of claim 1 , wherein the filter function of a highpass filter is used.

Assignees

• Siemens Ag

Inventors

• Bitter Ralf
• Hankiewicz Thomas
• Marquardt Christoph Wolfgang
• Mucha Adrian
• Nygren Jan
• Pleban Kai-Uwe
• Steinbacher Franz

Classifications

• G01N2021/399

  Diode laser · CPC title

• G01N21/39 Primary

  using tunable lasers · CPC title

• G01N33/0062

  concerning the measuring method or the display, e.g. intermittent measurement or digital display · CPC title

• G01J3/433

  Modulation spectrometry; Derivative spectrometry · CPC title

• G01J3/0286

  Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum · CPC title