WO1995004995A1 - Detection de gaz dissous dans un fluide sous pression - Google Patents

Detection de gaz dissous dans un fluide sous pression Download PDF

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Publication number
WO1995004995A1
WO1995004995A1 PCT/US1994/008916 US9408916W WO9504995A1 WO 1995004995 A1 WO1995004995 A1 WO 1995004995A1 US 9408916 W US9408916 W US 9408916W WO 9504995 A1 WO9504995 A1 WO 9504995A1
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WO
WIPO (PCT)
Prior art keywords
fluid
sensor element
resistance
dissolved gas
test
Prior art date
Application number
PCT/US1994/008916
Other languages
English (en)
Inventor
Robert H. Leyse
Original Assignee
Electric Power Research Institute, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Electric Power Research Institute, Inc. filed Critical Electric Power Research Institute, Inc.
Publication of WO1995004995A1 publication Critical patent/WO1995004995A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/14—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature
    • G01N27/18—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature caused by changes in the thermal conductivity of a surrounding material to be tested
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/02—Devices or arrangements for monitoring coolant or moderator
    • G21C17/022—Devices or arrangements for monitoring coolant or moderator for monitoring liquid coolants or moderators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to dissolved gases in fluids under pressure and, more particularly, to relating the electrical resistance of a sensor element to the presence of the dissolved gas.
  • a method and apparatus for measuring the gas content of metal samples is disclosed in U.S. Patent No. 3,177,700 issued to Sier.
  • a predetermined quantity of inert gas is present and a atarmeter is used to measure the amount of liberated gas using a Wheatstone bridge circuit.
  • U.S. Patent No. 4,965,041 issued to Becker discloses an instrument for monitoring the cooling conditions of the reactor core of a nuclear reactor. An electrical resistor is heated and the temperature of the resistor is monitored.
  • U.S. Patent No. 3,488,584 issued to Ziniuk discloses a high frequency bridge including a sensing probe disposed in a flowing liquid metal and a second probe in a reference sample of known purity. Thus any difference in electrical resistivity is due to a difference in contamination. None of these references are directed toward monitoring dissolved gas in a fluid such as water. A need for a simple rapid responding device for monitoring the presence of dissolved gas in a fluid is needed for applications such as in nuclear reactors.
  • an object of the present invention to provide an apparatus and method which can be used to monitor fluids for the presence of dissolved gas in the fluid. It is another object of the present invention to provide an apparatus having a sensing element to which power is applied in a stepwise manner and in which the resistance of the sensing element is related to the presence of dissolved gas in the water in which the sensing element is immersed.
  • an apparatus for determining the presence of dissolved gas in water under pressure The apparatus has a test cell capable of containing water and withstanding pressure of at least 2500 psi. The cell has an upper end and a lower end. eans are provided for introducing pressure into the upper end of the test cell.
  • a test instrument having a tip is disposed in the test cell.
  • the test instrument has a pair of spaced-apart platinum wires mounted in the tip thereof.
  • a sensor element is connected to the pair of platinum wires and a thermocouple is mounted in the test instrument.
  • Means are provided for applying electrical power through the platinum wires to the sensor element.
  • Means are provided for measuring the electrical resistance of the sensor element, wherein the electrical resistance of the sensor is a function of the dissolved gas in the water.
  • a method for determining the presence of dissolved gas in a fluid under pressure provides a test cell capable of containing water and withstanding pressure of at least 2500 psi.
  • a test instrument is disposed in the test cell, the test instrument having a sensor element to which electrical power can be applied. Means are provided for measuring the electrical resistance of the sensor element.
  • the test cell is calibrated at a measured temperature using degassed, demineralized fluid having a known resistance.
  • the power applied versus the resistance of the sensor element is recorded to determine the change of resistance.
  • the test cell is allowed to stabilize with a test fluid which is under a gas at a known pressure such that gas dissolves in the test fluid.
  • the temperature of the test fluid containing dissolved gas in the test instrument is measured.
  • FIG. 1 is a side elevation view of the apparatus of the present invention installed in a test cell for calibration and showing the pair of platinum wires, the sensor element and the thermocouple.
  • FIG. 2 is a side elevation view of the test instrument in a typical application.
  • FIG. 3 is a diagram showing the method of calibration of the present invention.
  • FIG. 4 is a plot of power versus resistance for degassed water.
  • FIG. 5 is a plot of power versus resistance for water saturated with nitrogen.
  • the apparatus 10 of the present invention has a test cell 11 which is a hollow tube, open at both ends with walls capable of withstanding pressures of at least 2500 psi.
  • the test cell may be glass or other material and, in situations where pressures up to 4000 psi may be encountered, the test cell may be formed of metal such as stainless steel.
  • the test cell has an internal cross section of approximately 0.28 inches and a length of approximately 10 inches, although test cells of differing configurations and dimensions may be used.
  • the top 12 of the test cell 11 has means formed thereon for connection to a source of pressure P such as the ambient pressurized system in which the apparatus 10 is used.
  • the means may be a fitting 13 or other connector.
  • the test instrument 15 be mounted in the bottom 14 of the test cell 11. The mounting is able to withstand pressure and is water tight to permit filling of the test cell with water.
  • the test instrument 15 is preferably in the shape of a probe which can be inserted into the test cell 11. Improved sealing of the test instrument 15 in the test cell may be achieved by O rings 20 about the test instrument 15. However, other sealing means may be used and the test instrument may have a shape which is not cylindrical.
  • a pair of spaced-apart platinum leads 21 are mounted near the first end of the test instrument 15.
  • the platinum leads 21 preferably have a diameter of 0.015 inches and are isolated by a core preferably formed from magnesium oxide to serve as an insulator.
  • the platinum leads 21 extend the length of the test instrument and means are provided to make electrical connections to the leads 21 at the second end of the test instrument 15 external of the test instrument for measurement purposes.
  • a sensor element 23 is connected to each of the platinum leads 21 at the first end of the test instrument 15 so as to form a bridge therebetween.
  • the sensor element 23 is a platinum wire approximately 0.1 inch long having a diameter of approximately 0.0003 inches.
  • a thermocouple 24 is mounted in the test instrument 15 adjacent to the sensor element 23 to monitor the water temperature.
  • Preferably a type K thermocouple is used.
  • a cap 25 may be formed on the tip of the test instrument 15 to cover the platinum leads 21, the sensor element 23 and the thermocouple 24.
  • the cap 25 may be in the form of a bell jar.
  • the cap 25 may be vented.
  • test cell 11 is evacuated to a vacuum of less than 0.01 inch mercury as measured with a gauge G, and then backfilled with degassed, demineralized fluid (such as water with a resistance of 10 megohms) .
  • degassed, demineralized fluid such as water with a resistance of 10 megohms
  • the system is pressurized to the test pressure with a hydrostatic test pump or similar means.
  • the bulk water temperature is measured with the type K thermocouple 24.
  • Testing then consists of increasing the power in steps (or continuously) and recording the applied voltage and electrical current at each step to determine the power (multiply voltage times current). Low currents (0.5 amp or less) are used to avoid significant heating of the sensor element 23 above the temperature of the fluid. The resistance of the sensor element 23 is recorded.
  • the test cell 11 is calibrated using degassed fluid.
  • several solutions are prepared, each having a known amount of gas dissolved therein.
  • the procedure is repeated for at least two pressures (i.e., 1100 psi and 2200 psi).
  • a calibration of the test cell 11 may be obtained. This permits determining the presence of dissolved gas at various pressures since the solubility of a gas increases with increased pressure.
  • the calibrated device 10 is evacuated and mounted in the equipment in which the pressurized fluid is to be monitored.
  • the fluid suspected of having gas dissolved therein is introduced into the device 10.
  • the test cell may be flushed with test fluid and allowed to stabilize under gas at a known pressure such that the gas dissolves in the test fluid and is in equilibrium with the gas above the test fluid.
  • the temperature of the fluid is measured.
  • the power is increased in steps and the voltage and amperage recorded at each step.
  • the resistance of the sensor element 33 is recorded.
  • the change in resistance of the sensor element 23 versus power is compared with the calibrated data and the presence of dissolved gas is determined.
  • the plot of power applied versus resistance of the degassed water at approximately 1000 psi is shown in FIG. 4.
  • a corresponding plot of water saturated with nitrogen at approximately 1000 psi is shown in FIG. 5. Comparison of FIGS.
  • the device may be used with fluids in which various gases are dissolved under pressure and is not limited to hydrogen or nitrogen, nor must the fluid be saturated with the gas.
  • the measurement of resistance compared to power is indicative of the presence of dissolved gas in the fluid.
  • the power is sequentially increased over a period of 5 seconds and then held constant or slightly decreased over a period of 5 seconds in a repeated manner.
  • the data is recorded and the comparative curves are plotted. Voltage, amperage, system pressure and fluid temperature are recorded at each step.
  • the device 10 of the present invention is very compact and can easily be inserted pipes in industrial applications such as the reference level pipes in a nuclear reactor installation.
  • the device 10 requires no special equipment for measuring the data produced; commercially available ammeters, voltmeters and ohmmeters can be used. There is no need for sampling lines with the attendant complexity and risk of loss of the sample character.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Plasma & Fusion (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

Dispositif et procédé servant à déterminer la présence de gaz dissous dans un fluide sous pression. Un instrument de contrôle (15) est situé à l'intérieur d'une cellule de contrôle (11) pouvant contenir le fluide sous pression. L'instrument de contrôle possède deux sondes en platine (21) reliées par un élément de détection (23). Les sondes en platine sont reliées à une source extérieure d'énergie électrique. Un thermocouple (24) est monté dans l'instrument de contrôle. Le dispositif est jaugé au moyen de fluide dégazé et déminéralisé à une pression connue par application d'énergie aux sondes en platine de manière progressive et par enregistrement de la résistance de l'élément de détection par rapport à l'énergie appliquée. La cellule de contrôle est reliée au fluide susceptible de contenir du gaz dissous et de l'énergie est appliquée aux sondes en platine de façon progressive. On enregistre l'énergie appliée par rapport à la résistance de l'élément de détection. La comparaison entre l'énergie par rapport à la résistance pour le fluide degazé et pour le fluide suspect met en évidence la présence de gaz dissous.
PCT/US1994/008916 1993-08-10 1994-08-03 Detection de gaz dissous dans un fluide sous pression WO1995004995A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10477993A 1993-08-10 1993-08-10
US08/104,779 1993-08-10

Publications (1)

Publication Number Publication Date
WO1995004995A1 true WO1995004995A1 (fr) 1995-02-16

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Family Applications (1)

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WO (1) WO1995004995A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3488584A (en) * 1965-05-04 1970-01-06 Atomic Power Dev Ass Inc Method and apparatus for resistivity measurement of flowing high temperature liquid metals
US4003814A (en) * 1974-08-02 1977-01-18 Noranda Mines Limited Apparatus for the continuous measurement of the oxygen content of molten copper or alloys thereof
US4361802A (en) * 1979-09-14 1982-11-30 Gould Godart B.V. Gas analyzer
US4383221A (en) * 1980-10-21 1983-05-10 Millipore Corporation Water resistivity sensor
US4978921A (en) * 1989-05-01 1990-12-18 General Electric Company Electrode probe for use in aqueous environments of high temperature and high radiation
US4990855A (en) * 1989-06-19 1991-02-05 General Electric Company Conductivity probe for use in the presence of high intensity nuclear radiation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3488584A (en) * 1965-05-04 1970-01-06 Atomic Power Dev Ass Inc Method and apparatus for resistivity measurement of flowing high temperature liquid metals
US4003814A (en) * 1974-08-02 1977-01-18 Noranda Mines Limited Apparatus for the continuous measurement of the oxygen content of molten copper or alloys thereof
US4361802A (en) * 1979-09-14 1982-11-30 Gould Godart B.V. Gas analyzer
US4383221A (en) * 1980-10-21 1983-05-10 Millipore Corporation Water resistivity sensor
US4978921A (en) * 1989-05-01 1990-12-18 General Electric Company Electrode probe for use in aqueous environments of high temperature and high radiation
US4990855A (en) * 1989-06-19 1991-02-05 General Electric Company Conductivity probe for use in the presence of high intensity nuclear radiation

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