LASER-TYPE GAS ANALYZER

• US 20150268159A1
• Filed: 06/05/2015
• Published: 09/24/2015
• Est. Priority Date: 01/11/2013
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: TABARU, Masaya, KOIZUMI, Kazuhiro, KONISHI, Hideyuki, INUI, Takashi
• Granted Patent: US 9,310,295 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 21/3103 Atomic absorption analysis
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/39 using tunable lasers
• CPC Class Codes: G01N 2201/0612 Laser diodes

Abstract

Aspects of a laser-type gas analyzer can include a mid-infrared light reception signal processing and computing unit that calculates a gas concentration of the first gas to be measured on the basis of a mid-infrared light reception signal, a near-infrared light reception signal processing and computing unit that detects, at respective times, the gas concentration of the second gas to be measured, water concentration in a space, and alight amount decrement due to dust, on the basis of near-infrared light reception signal. Also included can be a gas concentration correcting unit that corrects the gas concentrations of the first and second gases to be measured using the water concentration and the light amount decrement.

Claims

1. A laser-type gas analyzer, comprising:

a mid-infrared laser light-emitting unit that emits laser light of a wavelength band of a mid-infrared region that includes an optical absorption spectrum of a first gas to be measured;

a mid-infrared laser driving unit that drives the mid-infrared laser light-emitting unit;

a mid-infrared laser optical unit that collimates the laser light emitted by the mid-infrared laser light-emitting unit, and irradiates the light into a space to be measured in which the first gas to be measured is present;

a mid-infrared light-receiving unit that receives the laser light irradiated by the mid-infrared laser optical unit, and outputs the received laser light as an electrical mid-infrared light reception signal;

a mid-infrared light reception signal processing and computing unit that extracts, from the mid-infrared light reception signal, a signal component affected by optical absorption by the first gas to be measured, and calculates a gas concentration of the first gas to be measured on the basis of an amount of change of this signal component;

a near-infrared laser light-emitting unit that emits, at respective times, first laser light of a wavelength band of a near-infrared region that includes an optical absorption spectrum of a second gas to be measured, second laser light of a wavelength band of a near-infrared region that includes an optical absorption spectrum of water, and third laser light of a wavelength band of a near-infrared region in which the optical absorption spectra of water, the first gas to be measured and the second gas to be measured are equal to or smaller than a predetermined amount;

a near-infrared laser driving unit that drives the near-infrared laser light-emitting unit;

a near-infrared laser optical unit that collimates, at respective times, the first, second and third laser light emitted by the near-infrared laser light-emitting unit, and irradiates the collimated light to the space to be measured;

a near-infrared light-receiving unit that receives, at respective times, the first, second and third laser light irradiated by the near-infrared laser optical unit, and outputs the received light as respective electrical near-infrared light reception signals;

a near-infrared light reception signal processing and computing unit that performs, at respective times, processes of extracting, from the near-infrared light reception signal of the first laser light, a signal component affected by optical absorption by the second gas to be measured, and computing a gas concentration of the second gas to be measured on the basis of an amount of change of this signal component, computing a water concentration in the space on the basis of the near-infrared light reception signal of the second laser light, and computing a light amount decrement due to dust on the basis of the near-infrared light reception signal of the third laser light; and

a gas concentration correcting unit that corrects the gas concentration of the first gas to be measured, as worked out by the mid-infrared light reception signal processing and computing unit and the gas concentration of the second gas to be measured, as worked out by the near-infrared light reception signal processing and computing unit, in use of the water concentration and light amount decrement as worked out by the near-infrared light reception signal processing and computing unit.

2. The laser-type gas analyzer according to claim 1,

wherein the first gas to be measured is SO₂ gas and the second gas to be measured is CO₂ gas.

3. The laser-type gas analyzer according to claim 2,

wherein the wavelength of laser light of the mid-infrared region emitted by the mid-infrared laser light-emitting unit ranges from 3 to 10 μ

m, and the wavelength of the laser light of the near-infrared region emitted by the near-infrared laser light-emitting unit ranges from 0.7 to 3 μ

m.