US3721897A - Wall thickness and temperature monitoring apparatus for boiler tubes - Google Patents

Wall thickness and temperature monitoring apparatus for boiler tubes Download PDF

Info

Publication number
US3721897A
US3721897A US00141409A US3721897DA US3721897A US 3721897 A US3721897 A US 3721897A US 00141409 A US00141409 A US 00141409A US 3721897D A US3721897D A US 3721897DA US 3721897 A US3721897 A US 3721897A
Authority
US
United States
Prior art keywords
tube
boiler
measuring
temperature
tubes
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US00141409A
Other languages
English (en)
Inventor
G Edling
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AKA APPARATKEMISKA AB
APPARATKEMISKA AKA SW AB
Original Assignee
AKA APPARATKEMISKA AB
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 AKA APPARATKEMISKA AB filed Critical AKA APPARATKEMISKA AB
Application granted granted Critical
Publication of US3721897A publication Critical patent/US3721897A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
    • G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness

Definitions

  • the heat from hot gases to the water (and vapour) content of the boiler is supplied through a tube Wall.
  • the tube wall part where the heat passage takes place is given a temperature exceeding that of the water inside the tube.
  • the magnitude of the increase in temperature depends on the heat amount, on the conductivity of the tube material and on the heat transfer resistances on the gas side as well as on the water side.
  • a coating (boiler scale) on the tube inside increases the heat transfer resistance on the inside of the tube, thereby rendering the heat transport more difficult and increasing the temperature of the tube material.
  • the fuel used and also other operation conditions can involve the risk that the thickness of the tube wall is reduced by corrosion on the fume side. Corrosion can also be caused on the water side. If by such corrosion the tube material is weakened, this weakening may be such that it results in a breaking of the tube. Tube breaks of this type disturb the operation and can in certain cases involve catastrophic risks for the life and health of the personnel as well as for substantial damages of the installation and the expenditures connected therewith.
  • the tubes on the fume side can be cleaned carefully and thereafter the tube wall be tested by using ultrasonic or other type of non-destructive testing.
  • the present invention solves the aforesaid diiiiculties and problems in a superior way.
  • the invention is defined in the claims and relates to a method of controlling the condition and operational safety of the tubes by measuring the electric resistance of the tube.
  • the invention is based on the known physical laws as follows.
  • the electric resistance in a conductor is proportional to the length of the conductor and inversely proportional to its area.
  • the electric resistivity increases according to known laws with the temperature of the conductor.
  • FIG. 1 shows a partially heated boiler tube in a section and in a schematic view showing how the measuring devices are mounted
  • $16. 2 shows in a section several tubes, which are provided with ribs and welded together.
  • the designations 1, 2, 3 and 4 refer to different parts of a tube cross-section.
  • the tube is provided with connecting terminals 5 and 6 for electric current.
  • a voltmeter 9 is connected to the tube via a pair of measuring terminals 7 and 8.
  • an electric current with known and constant amperage is supplied from a source 10 of constant current to the connecting terminals 5 and 6.
  • the current passes through the current path in the tube, which path comprises the connecting terminal 5, tube part 4 and connecting terminal 6, and through the current path comprising the connecting terminal 5, tube part 2 and connecting terminal 6, the current intensity in the two paths being inversely proportional to the resistance of the paths.
  • Such an increase'in resistance can have its reason in a temperature increase in the tube part 4 or in a reduced sectional area for the current through the tube part 4.
  • the voltmeter 9 indicates voltages corresponding to values being characteristic of the operation. If during operation the tube wall in the parts 1-4- 3 is weakened by external and/or internal corrosion, the voltage on voltmeter 9 increases. Such is also the case if the temperature of the tube material due to the prevailing operational conditions increases. Such a temperature increase, for example, may be caused by internal coatings on the tube or by too high load. In any case, a voltage increase on the voltmeter 9 signals unpermitted operation conditions.
  • the voltage drop between the measuring terminals 7 and 8 is determined under isothermal conditions.
  • the relation between this voltage drop and the temperature in the heated tube part 4 can thereby be determined empirically.
  • the temperature in tube part 2 which normally follows the temperature of the water, must be measured. This can be carried out, for example, by thermocouple elements or corresponding thermometers. The temperature measured is thereafter to be used for the correction of further evaluations of the main measurement.
  • the temperature in the tube water is measured separately.
  • FIG. 2 shows such a tube arrangement where the tubes 11 are provided with ribs 12 joined together by welds 13 to form a tube board. It is there possible to control several tubes by the same measurement, in that the constant current is supplied to the connecting terminals 5 and 6 which are not mounted on the same tube, and the voltage drop is measured between the measuring terminals 7 and 8 which are not mounted on the same tube, either.
  • the measuring of the voltage can also be made directly between the connecting terminals 5 and 6. This can be of advantage at entirely heated tubes, on which the connecting terminals 5 and 6 are separated in the longitudinal direction of the tube.
  • Every tube or tube board may be provided with several pairs of connecting terminals or/and several pairs of measuring terminals, depending on the geometric design of the tube.
  • control measurements in operation can be carried out manually or automatically with cyclic switchingto the current source and measuring device. At unnormal conditions, alarm and actions, such as shut down, can be released automatically.
  • Apparatus for continuously or intermittently monitoring operating conditions of a boiler tube during boiler operation comprising a pair of spaced current terminals mounted on the outer surface of a boiler tube wall in a cross-sectional plane thereof, said terminals being mounted on that side of the tube wall remote from the direct source of heat for heating the boiler tube so as to provide two current paths through a cross-section of the tube wall,

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)
US00141409A 1968-03-14 1971-05-07 Wall thickness and temperature monitoring apparatus for boiler tubes Expired - Lifetime US3721897A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE3352/68A SE320676B (enrdf_load_html_response) 1968-03-14 1968-03-14

Publications (1)

Publication Number Publication Date
US3721897A true US3721897A (en) 1973-03-20

Family

ID=20261937

Family Applications (1)

Application Number Title Priority Date Filing Date
US00141409A Expired - Lifetime US3721897A (en) 1968-03-14 1971-05-07 Wall thickness and temperature monitoring apparatus for boiler tubes

Country Status (2)

Country Link
US (1) US3721897A (enrdf_load_html_response)
SE (1) SE320676B (enrdf_load_html_response)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3974443A (en) * 1975-01-02 1976-08-10 International Business Machines Corporation Conductive line width and resistivity measuring system
US3995213A (en) * 1975-10-02 1976-11-30 The United States Of America As Represented By The Secretary Of The Air Force Surface impedance tester
FR2468876A1 (fr) * 1979-10-31 1981-05-08 Fiat Ricerche Procede et appareil de mesure de l'epaisseur d'une couche superficielle dans une piece metallique
US5165794A (en) * 1991-08-02 1992-11-24 The United States Of America As Represented By The United States Department Of Energy Method for the thermal characterization, visualization, and integrity evaluation of conducting material samples or complex structures
US5166627A (en) * 1991-05-30 1992-11-24 The United States Of America As Represented By The United States Department Of Energy Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement
US5171517A (en) * 1990-12-10 1992-12-15 General Electric Company Method for monitoring corrosion on a member in a nuclear reactor core
US5217304A (en) * 1991-08-02 1993-06-08 The United States Of America As Represented By The United States Department Of Energy Electrical network method for the thermal or structural characterization of a conducting material sample or structure
US5346307A (en) * 1993-06-03 1994-09-13 Regents Of The University Of California Using electrical resistance tomography to map subsurface temperatures
US6288528B1 (en) 1999-05-18 2001-09-11 Alstom Power Inc. Method and system for evaluating a condition of a combustion vessel
WO2001094876A1 (en) * 2000-06-06 2001-12-13 Alstom Power Inc. Monitoring of fouling or of loss of material of heat transfer tubes in a combustion vessel by resistance measurements
WO2003019167A1 (en) * 2001-08-21 2003-03-06 Alstom Technology Ltd. Regularization model for electrical resistance mapping
US20060033504A1 (en) * 2004-08-10 2006-02-16 United Technologies Corporation Non-destructive monitoring of material integrity
EP1655569A1 (de) * 2004-11-03 2006-05-10 Nexans Verfahren zur Ermittlung der Wanddicke eines Metallrohres
WO2009153323A1 (fr) * 2008-06-18 2009-12-23 Electricite De France Procédé et dispositif pour la détection et/ou la mesure d'encrassement dans des échangeurs
US20220148747A1 (en) * 2020-11-12 2022-05-12 Westinghouse Electric Company Llc System and method for local resistivity measurement and critical heat flux calculation for nuclear reactor cladding tubing
WO2022165482A2 (en) 2021-01-29 2022-08-04 General Electric Company Method and system for assessing a condition of a boiler

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3974443A (en) * 1975-01-02 1976-08-10 International Business Machines Corporation Conductive line width and resistivity measuring system
US3995213A (en) * 1975-10-02 1976-11-30 The United States Of America As Represented By The Secretary Of The Air Force Surface impedance tester
FR2468876A1 (fr) * 1979-10-31 1981-05-08 Fiat Ricerche Procede et appareil de mesure de l'epaisseur d'une couche superficielle dans une piece metallique
US5171517A (en) * 1990-12-10 1992-12-15 General Electric Company Method for monitoring corrosion on a member in a nuclear reactor core
US5166627A (en) * 1991-05-30 1992-11-24 The United States Of America As Represented By The United States Department Of Energy Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement
US5217304A (en) * 1991-08-02 1993-06-08 The United States Of America As Represented By The United States Department Of Energy Electrical network method for the thermal or structural characterization of a conducting material sample or structure
US5165794A (en) * 1991-08-02 1992-11-24 The United States Of America As Represented By The United States Department Of Energy Method for the thermal characterization, visualization, and integrity evaluation of conducting material samples or complex structures
US5346307A (en) * 1993-06-03 1994-09-13 Regents Of The University Of California Using electrical resistance tomography to map subsurface temperatures
US6288528B1 (en) 1999-05-18 2001-09-11 Alstom Power Inc. Method and system for evaluating a condition of a combustion vessel
WO2001094876A1 (en) * 2000-06-06 2001-12-13 Alstom Power Inc. Monitoring of fouling or of loss of material of heat transfer tubes in a combustion vessel by resistance measurements
WO2003019167A1 (en) * 2001-08-21 2003-03-06 Alstom Technology Ltd. Regularization model for electrical resistance mapping
US7157920B2 (en) * 2004-08-10 2007-01-02 United Technologies Corporation Non-destructive monitoring of material integrity
US20060033504A1 (en) * 2004-08-10 2006-02-16 United Technologies Corporation Non-destructive monitoring of material integrity
EP1655569A1 (de) * 2004-11-03 2006-05-10 Nexans Verfahren zur Ermittlung der Wanddicke eines Metallrohres
RU2372584C2 (ru) * 2004-11-03 2009-11-10 Нексанс Способ определения толщины стенки металлической трубы
WO2009153323A1 (fr) * 2008-06-18 2009-12-23 Electricite De France Procédé et dispositif pour la détection et/ou la mesure d'encrassement dans des échangeurs
FR2932886A1 (fr) * 2008-06-18 2009-12-25 Electricite De France Procede et dispositif pour la detection et/ou la mesure d'encrassement dans des echangeurs
US20110080182A1 (en) * 2008-06-18 2011-04-07 Veau Jose Method and device for the detection and/or measurement of fouling in heat exchangers
JP2011524981A (ja) * 2008-06-18 2011-09-08 エレクトリシテ・ドゥ・フランス 熱交換器内のファウリングの検出及び／又は測定のための方法及び装置
US8672537B2 (en) 2008-06-18 2014-03-18 Electricite De France Method and device for the detection and/or measurement of fouling in heat exchangers
US20220148747A1 (en) * 2020-11-12 2022-05-12 Westinghouse Electric Company Llc System and method for local resistivity measurement and critical heat flux calculation for nuclear reactor cladding tubing
US12322519B2 (en) * 2020-11-12 2025-06-03 Westinghouse Electric Company Llc System and method for local resistivity measurement and critical heat flux calculation for nuclear reactor cladding tubing
WO2022165482A2 (en) 2021-01-29 2022-08-04 General Electric Company Method and system for assessing a condition of a boiler
US11480332B2 (en) 2021-01-29 2022-10-25 General Electric Company Method and system for assessing a condition of a boiler

Also Published As

Publication number Publication date
SE320676B (enrdf_load_html_response) 1970-02-16

Similar Documents

Publication Publication Date Title
US3721897A (en) Wall thickness and temperature monitoring apparatus for boiler tubes
US1998952A (en) Rail inspection apparatus
US4912418A (en) Method and device for detecting the location of a fault within a dielectric layer of an electrically conducting pipe
US3279252A (en) Level sensing apparatus
US2757362A (en) Fuel tank leak detector
SE461301B (sv) Avkaenningsanordning foer detektering av aatminstone en korrosiv foerorening i ett fludium
US3864960A (en) Vacuum leak detector
US3599090A (en) Apparatus for detecting and measuring crevice corrosion
US2987672A (en) Impedance test apparatus
US3558462A (en) Probe assembly for corrosion tests
US2766442A (en) Leak detection apparatus
US3111388A (en) Method for testing electrical instrumentalities for incipient fault
US3410764A (en) Corrosion detecting and analyzing devices
US3406103A (en) Method and apparatus for monitoring lining damage of alkali metal chlorate bipolar cells
US2992310A (en) Fire detector made of two special electric wires
US3166901A (en) Detector for alkali-metal vapors
US2852738A (en) Protection tube leak-checker for thermocouples
KR101958626B1 (ko) 증기 발생기의 균열 탐지 장치 및 방법
US3077505A (en) High temperature thermocouple
Sithiravelautham et al. Transformer Maintenance Using IR Thermography
US3370457A (en) Gas detector
US4098112A (en) Steam turbine expansion joint with probe for monitoring molten caustics
Hong et al. Research on using resistant sensor to predict corrosion under insulation of carbon steel
Phuakphewvong et al. Computational Based Methodology to Investigate Pipe Thickness Using Thermal Nondestructive Technique
SU416633A1 (enrdf_load_html_response)