US6037592A
Expired / Lapsed
US
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System for measuring gases dissolved in a liquid
Assignee: Underground Systems Inc
•
Filing: 1997-02-14
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Granted: 2000-03-14
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Expires: 2017-02-14
Abstract
Abstract A method and apparatus for continuously monitoring and measuring the concentration of gases in a gas-containing liquid such as a transformer oil. The method and apparatus employ a passive gas extraction technique which comprises a high performance membrane material to extract dissolved gases from the oil, and an IR-based sensor to detect gases present. The passive gas extractor extracts dissolved gas from the gas-containing liquid, there being a known relationship between the concentration of a constituent gas in the extracted gas and the concentration of the constituent gas remaining dissolved in the gas-containing liquid. The gas sensor senses the concentration of a constituent gas in the extracted gas, in the presence of other constituent gases. The gas sensor comprises a sample chamber which receives the extracted gas, a non-dispersive infrared (IR) absorption sensing system which generates an electrical signal corresponding to the light absorption, at one or more specified IR wavelengths, of the extracted gas in the chamber, and an electrical output comprising the electrical signal generated by the non-dispersive IR absorption sensing system. A processor having receives the electrical signal corresponding to the light absorption, at the one or more specified IR wavelengths, of the extracted gas in the chamber, and computes the concentration of at least one gas constituent present in the extracted gas.
Inventors
- 👤 Steven S. Sunshine
- 👤 David C. Bliven
- 👤 John Seymour Mattis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:06
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/26; G01N33/28; G01N33/2835; G01N33/2841; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/35; G01N21/3504
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
291 words
A sensor system for measuring the concentration of gas dissolved in a liquid, the gas comprising one or more constituent gases in a distribution, the system comprising: a. a passive extractor which extracts dissolved gas from the gas-containing liquid, there being a known relationship between the concentration of a constituent gas in the extracted gas and the concentration of the constituent gas remaining dissolved in the gas-containing liquid; and b. a gas sensor which senses the concentration of a constituent gas in the extracted gas, in the presence of other constituent gases, the gas sensor comprising (1) a sample chamber having plural tubes which receive the extracted gas, (2) a non-dispersive infrared (IR) absorption sensing system which generates an electrical signal corresponding to the light absorption, at one or more specified IR wavelengths, of the extracted gas in the chamber, and (3) an electrical output comprising the electrical signal generated by the non-dispersive IR absorption sensing system comprising a respective IR emitter disposed at one end of a respective tube, each IR emitter comprising a blackbody source for emitting IR light with wavelengths in the range 2.5 to 15 μm, a filter for limiting the IR light transmitted in each tube to a respective sub-range of wavelengths, and plural IR detectors disposed at an opposite end of each of said tubes for receiving the light transmitted in said tube to produce an electrical output signal as a function of the intensity of the received light, each IR detector being tuned to a predetermined wavelength in said respective sub-range corresponding to a respective one of said constituent gases to produce a detection signal representing the presence of said one constituent gas if IR light at said predetermined wavelength is of reduced intensity.
Claim 2
Dependent Claim
291 words
A sensor system for measuring the concentration of gas dissolved in a liquid, the gas comprising one or more constituent gases in a distribution, the system comprising: a. a passive extractor which extracts dissolved gas from the gas-containing liquid, there being a known relationship between the concentration of a constituent gas in the extracted gas and the concentration of the constituent gas remaining dissolved in the gas-containing liquid; and b. a gas sensor which senses the concentration of a constituent gas in the extracted gas, in the presence of other constituent gases, the gas sensor comprising (1) a sample chamber having plural tubes which receive the extracted gas, (2) a non-dispersive infrared (IR) absorption sensing system which generates an electrical signal corresponding to the light absorption, at one or more specified IR wavelengths, of the extracted gas in the chamber, and (3) an electrical output comprising the electrical signal generated by the non-dispersive IR absorption sensing system comprising a respective IR emitter disposed at one end of a respective tube, each IR emitter comprising a blackbody source for emitting IR light with wavelengths in the range 2.5 to 15 μm, a filter for limiting the IR light transmitted in each tube to a respective sub-range of wavelengths, and plural IR detectors disposed at an opposite end of each of said tubes for receiving the light transmitted in said tube to produce an electrical output signal as a function of the intensity of the received light, each IR detector being tuned to a predetermined wavelength in said respective sub-range corresponding to a respective one of said constituent gases to produce a detection signal representing the presence of said one constituent gas if IR light at said predetermined wavelength is of reduced intensity.
Claim 3
Dependent Claim
35 words
The sensor system according to claim 1 comprising a compressor receiving the detection signals produced by said IR detectors, and therefrom computing the concentration of at least one constituent gas present in the extracted gas.
Claim 4
Dependent Claim
28 words
The system according to claim 1 comprising: a. means for receiving a gas-containing liquid from a liquid reservoir; and b. means for returning liquid to the liquid reservoir.
Claim 5
Dependent Claim
27 words
The system according to claim 1 comprising: a. means for passing extracted gas to the gas sensor; and b. means for returning extracted gas to the liquid.
Claim 6
Dependent Claim
18 words
The system according to claim 1 comprising means for regulating the temperature of the liquid in the system.
Claim 7
Dependent Claim
25 words
The system according to claim 5, wherein the temperature regulating means comprises at least one of a. a heat exchanger; and b. a thermoelectric device.
Claim 8
Dependent Claim
18 words
The system according to claim 1 comprising means for measuring the temperature of the liquid in the system.
Claim 9
Dependent Claim
22 words
The system according to claim 1, wherein the liquid reservoir comprises an electrical transformer and the gas-containing liquid comprises a transformer oil.
Claim 10
Dependent Claim
42 words
The system according to claim 1, wherein the IR detectors detect IR light at respective ones of the following wavelengths: (1) 2.59 μm, (2) 3.32 μm, (3) 4.25 μm, (4) 4.67 μm, (5) 7.65 μm, (6) 10.6 μm, and (7) 13.7 μm.
Claim 11
Dependent Claim
15 words
The system according to claim 1, wherein the gas sensor comprises a thermal conductivity sensor.
Claim 12
Dependent Claim
29 words
The system according to claim 9, wherein selected ones of the IR detectors detect light at respective ones of the following wavelengths: a. 3.91 μm, and b. 9 μm.
Claim 13
Dependent Claim
28 words
The system according to claim 9, wherein the IR emitter is separated from the IR detectors in a tube by an optical path of at least one inch.
Claim 14
Dependent Claim
36 words
The system according to claim 9, wherein each IR detector comprises a broadband detector and a narrow band filter, the narrow band filter having a full width half maximum (FWHM) bandwidth of less than 0.5 μm.
Claim 15
Dependent Claim
112 words
The system according to claim 10, wherein the thermal conductivity sensor comprises a bridge circuit, the bridge circuit comprising: a. an electrical input; b. a first negative temperature coefficient (NTC) thermistor; c. a second NTC thermistor; and c. an electrical output; wherein the resistance of the first NTC thermistor varies as a function of the temperature of the extracted gas present in the sample chamber, the resistance of the second NTC thermistor varies as a function of the temperature of the sample chamber, and the electrical output of the thermal conductivity sensor comprises an electrical signal which is representative of the difference between the resistances of the first and second NTC thermistors.
Claim 16
Dependent Claim
62 words
The system according to claim 14, wherein the processor has an input coupled with the electrical output of the thermal conductivity sensor, the processor receiving the electrical signal corresponding to the difference between the resistances of the first and second NTC thermistors, and therefrom computing the thermal conductivity of the extracted gas and the concentration of hydrogen present in the extracted gas.
Claim 17
Dependent Claim
228 words
A sensor system for measuring the concentration of gas dissolved in a liquid, the gas comprising one or more constituent gases in a distribution, the system comprising: a. a passive gas extractor which extracts dissolved gas from the gas-containing liquid, there being a known relationship between the concentration of a constituent gas in the extracted gas and the concentration of the constituent gas remaining dissolved in the gas-containing liquid; and b. a gas sensor which senses the concentration of a constituent gas in the extracted gas, in the presence of other constituent gases, the gas sensor comprising (1) a sample chamber which receives the extracted gas, (2) a non-dispersive infrared (IR) absorption sensing system which generates an electrical signal corresponding to the light absorption, at one or more specified IR wavelengths, of the extracted gas in the chamber, the non-dispersive IR absorption sensing system comprising an IR emitter assembly and an IR detector assembly, wherein: a. the IR emitter assembly comprises a blackbody source which emits light from 2.5 to 15 μm; and b. the IR detector assembly comprises six IR detectors with each IR detector detecting light at a different one of the following wavelengths: 2.59 μm, 3.32 μm, 4.25 μm, 4.67 μm, 7.65 μm, 10.6 μm, and 13.7 μm; and (3) an electrical output comprising the electrical signal generated by the non-dispersive IR absorption sensing system.
Claim 18
Dependent Claim
228 words
A sensor system for measuring the concentration of gas dissolved in a liquid, the gas comprising one or more constituent gases in a distribution, the system comprising: a. a passive gas extractor which extracts dissolved gas from the gas-containing liquid, there being a known relationship between the concentration of a constituent gas in the extracted gas and the concentration of the constituent gas remaining dissolved in the gas-containing liquid; and b. a gas sensor which senses the concentration of a constituent gas in the extracted gas, in the presence of other constituent gases, the gas sensor comprising (1) a sample chamber which receives the extracted gas, (2) a non-dispersive infrared (IR) absorption sensing system which generates an electrical signal corresponding to the light absorption, at one or more specified IR wavelengths, of the extracted gas in the chamber, the non-dispersive IR absorption sensing system comprising an IR emitter assembly and an IR detector assembly, wherein: a. the IR emitter assembly comprises a blackbody source which emits light from 2.5 to 15 μm; and b. the IR detector assembly comprises six IR detectors with each IR detector detecting light at a different one of the following wavelengths: 2.59 μm, 3.32 μm, 4.25 μm, 4.67 μm, 7.65 μm, 10.6 μm, and 13.7 μm; and (3) an electrical output comprising the electrical signal generated by the non-dispersive IR absorption sensing system.
Claim 19
Dependent Claim
64 words
The sensor system according to claim 16 comprising a processor having an input coupled with the electrical output of the gas sensor, the processor receiving the electrical signal corresponding to the light absorption, at the one or more specified IR wavelengths, of the extracted gas in the chamber, and therefrom computing the concentration of at least one gas constituent present in the extracted gas.
Claim 20
Dependent Claim
28 words
The system according to claim 16 comprising: a. means for receiving a gas-containing liquid from a liquid reservoir; and b. means for returning liquid to the liquid reservoir.
Claim 21
Dependent Claim
27 words
The system according to claim 16 comprising: a. means for passing extracted gas to the gas sensor; and b. means for returning extracted gas to the liquid.
Claim 22
Dependent Claim
18 words
The system according to claim 16 comprising means for regulating the temperature of the liquid in the system.
Claim 23
Dependent Claim
25 words
The system according to claim 20, wherein the temperature regulating means comprises at least one of a. a heat exchangerl and b. a thermoelectric device.
Claim 24
Dependent Claim
18 words
The system according to claim 16 comprising means for measuring the temperature of the liquid in the system.
Claim 25
Dependent Claim
31 words
The system according to claim 16, wherein the IR detector assembly comprises an IR detector which detects light at one of the following wavelengths: a. 3.91 μm.; and b. 9 μm.
Claim 26
Dependent Claim
20 words
The system according to claim 16, wherein the IR detector assembly has an optical path of at least one inch.
Claim 27
Dependent Claim
36 words
The system according to claim 16, wherein the IR detector comprises a broadband detector and a narrow band filter, the narrow band filter having a full width half maximum (FWHM) bandwidth of less than 0.5 μm.
Claim 28
Dependent Claim
16 words
The system according to claim 16, wherein the gas sensor further comprises a thermal conductivity sensor.
Claim 29
Dependent Claim
112 words
The system according to claim 26, wherein the thermal conductivity sensor comprises a bridge circuit, the bridge circuit comprising: a. an electrical input; b. a first negative temperature coefficient (NTC) thermistor; c. a second NTC thermistor; and c. an electrical output; wherein the resistance of the first NTC thermistor varies as a function of the temperature of the extracted gas present in the sample chamber, the resistance of the second NTC thermistor varies as a function of the temperature of the sample chamber, and the electrical output of the thermal conductivity sensor comprises an electrical signal which is representative of the difference between the resistances of the first and second NTC thermistors.
Claim 30
Dependent Claim
62 words
The system according to claim 27, wherein the processor has an input coupled with the electrical output of the thermal conductivity sensor, the processor receiving the electrical signal corresponding to the difference between the resistances of the first and second NTC thermistors, and therefrom computing the thermal conductivity of the extracted gas and the concentration of hydrogen present in the extracted gas.
Claim 31
Dependent Claim
22 words
The system according to claim 16, wherein the liquid reservoir comprises an electrical transformer and the gas-containing liquid comprises a transformer oil.
Claim 32
Dependent Claim
20 words
The system according to claim 16, wherein the passive gas extractor comprises a permselective membrane comprising an amorphous perfluoro-2,2-dimethyl-1,3-dioxole polymer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-03-14 | 2003-09-13 | 2004-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-03-14 | 2007-09-13 | 2008-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-03-14 | 2011-09-13 | 2012-03-14 | $7700.00 | Window Closed / Lapsed |