EP1287309A1 - Controle du colmatage ou de la fuite de matiere de tubes de transfert thermique dans une cuve de combustion par mesures de resistance - Google Patents

Controle du colmatage ou de la fuite de matiere de tubes de transfert thermique dans une cuve de combustion par mesures de resistance

Info

Publication number
EP1287309A1
EP1287309A1 EP00938186A EP00938186A EP1287309A1 EP 1287309 A1 EP1287309 A1 EP 1287309A1 EP 00938186 A EP00938186 A EP 00938186A EP 00938186 A EP00938186 A EP 00938186A EP 1287309 A1 EP1287309 A1 EP 1287309A1
Authority
EP
European Patent Office
Prior art keywords
electrical network
evaluating
characteristic
milestone
combustion vessel
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.)
Ceased
Application number
EP00938186A
Other languages
German (de)
English (en)
Inventor
Stephen L. Goodstine
Jonathan S. Simon
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.)
Alstom Power Inc
Original Assignee
Alstom Power 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 Alstom Power Inc filed Critical Alstom Power Inc
Publication of EP1287309A1 publication Critical patent/EP1287309A1/fr
Ceased legal-status Critical Current

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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
    • G01N27/20—Investigating the presence of flaws
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
    • G01K1/02—Means for indicating or recording specially adapted for thermometers
    • G01K1/026—Means for indicating or recording specially adapted for thermometers arrangements for monitoring a plurality of temperatures, e.g. by multiplexing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
    • G01N17/008—Monitoring fouling

Definitions

  • the present invention relates to a method and system for evaluating a condition of a combustion vessel and, more particularly, to a method and system for evaluating a condition of a combustion vessel as a function of a detected electrical characteristic of the combustion vessel.
  • combustion related material such as ash based combustion byproduct on deposition exposed surfaces of the vessel.
  • combustion related material such as ash based combustion byproduct
  • loss or wastage of such deposition exposed surfaces or other structure of the combustion vessel which results from the
  • US Patent No. 4,176, 554 discloses a method for evaluating a temperature profile of a kiln which includes the steps of obtaining a temperature profile of the kiln based upon temperature
  • US Patent No. 5, 615, 953 discloses a system for obtaining a temperature profile of a bank of tubes of a fossil fuel-fired boiler in order to determine the amount of build up on the tubes.
  • a series of temperature readings are taken at intervals along the length of an extension arm, such as a sootblower lance, which is extended near the tube banks of a boiler.
  • the temperature readings are integrated to form a temperature profile from which conclusions may be drawn concerning the accumulation of the tube banks of the boiler.
  • a method for evaluating a location of interest of a combustion vessel preferably comprises the steps of imposing a current on an electrical network, the electrical network having at least one electrode and being situated relative to the combustion vessel such that properties of the electrical network are influenced by the operation of the combustion vessel.
  • the method further preferably comprises the step of detecting at least one characteristic of the electrical network during the step of imposing a current on the electrical network.
  • the method additionally includes the step of evaluating a condition of the combustion vessel based upon the at least one detected characteristic of the electrical network.
  • a fossil fuel is combusted during the combustion process in the combustion vessel and the step of evaluating a condition of the combustion vessel surface includes evaluating the at least one detected characteristic of the electrical network as an indicator of a characteristic of a surface of the combustion vessel.
  • the step of evaluating the at least one detected characteristic of the electrical network as an indicator of a characteristic of the surface of the combustion vessel surface includes evaluating the at least one detected characteristic of the electrical network as an indicator of a reduction of heat flux.
  • the step of evaluating the at least one detected characteristic of the electrical network as an indicator of the reduction of heat flux includes evaluating a detected resistance value in the electrical network which is relatively greater than a baseline resistance value existing at a baseline time prior to the imposition of a current on the electrical network during the step of imposing of a current on the electrical network as an indicator that the reduction of heat flux is different than the heat flux at the baseline time.
  • a system for evaluating a condition of a surface of a combustion vessel exposed to deposition thereon of a material released during a combustion of a fuel in the combustion vessel during a combustion process comprising means for imposing a current on an electrical network having at least one electrode and means for detecting at least one characteristic of the electrical network during the step of imposing a current on the electrical network.
  • the system also includes means for evaluating a condition of the deposition exposed surface based upon the at least one detected characteristic of the electrical network.
  • the system preferably includes, in one variation thereof, means for evaluating a condition of the combustion vessel surface which is operable to evaluate the at least one detected characteristic of the electrical network as an indicator of a characteristic of the deposition on the combustion vessel surface. Additionally, if the material released during the combustion process is ash based combustion byproduct, the means for evaluating the at least one detected characteristic of the electrical network as an indicator of a characteristic of the deposition on the combustion vessel surface is, in one variation thereof, operable to evaluate the at least one detected characteristic of the electrical network as an indicator of the reduction of heat flux.
  • a further variation of the system preferably includes the feature that the means for evaluating the at least one detected characteristic of the electrical network as an indicator of the reduction of heat flux is operable to evaluate a detected resistance value in the electrical network which is different than a baseline resistance value existing at a baseline time prior to the imposition of a current on the electrical network while a current is imposed on the electrical network as an indicator that the depth of deposition on the combustion vessel surface is relatively greater than the depth of deposition at the baseline time.
  • the means for detecting in this variation of the system, is preferably operable to detect a resistance value and the means for evaluating includes means for comparing the at least one detected characteristic with at least one predetermined resistance value.
  • This iterative method also includes the step of comparing each detected resistance/voltage value with a comparison stored resistance/voltage value set having at least one resistance voltage value stored in a database of predetermined resistance/voltage values, each resistance/voltage value of the comparison stored resistance/voltage value set characterizing the combustion vessel surface at a time other than the respective current imposing interval.
  • a method operable to evaluate a combustion vessel in which a combustion process occurs which contributes to a slagging process in which slag accrues on surfaces of the combustion vessel includes the step of evaluating includes determining that a condition of slagging exists in the combustion vessel in the event that: (1) the interval between the reference time and the milestone time is less than a predetermined magnitude and (2) a variation exists between the reference resistance characteristic and the milestone resistance characteristic.
  • the step of evaluating of this further method of the present invention also preferably includes determining that a condition of slagging exists in the combustion vessel in the event that: (1) the interval between the reference time and the milestone time is less than a predetermined magnitude and (2) a variation greater than a predetermined magnitude exists between the reference resistance characteristic and the milestone resistance characteristic.
  • the step of evaluating includes determining that a condition of a build up of deposition material on the firesides of the tubes exists in the event that: (1) the interval between the reference time and the milestone time is greater than a predetermined magnitude and (2) a variation greater than a predetermined magnitude exists between the reference resistance characteristic and the milestone resistance characteristic.
  • the method includes detecting at a milestone time a resistance characteristic of a electrical network having at least two electrodes disposed relative to a portion of interest of the combustion vessel for passing a current therethrough to thereby enable the milestone resistance characteristic to be obtained, the portion of interest of the combustion vessel being characterized by a milestone temperature at the milestone time and evaluating the milestone resistance characteristic.
  • the evaluation of the milestone reference characteristic includes evaluating this characteristic with respect to a reference resistance characteristic of the electrical network which characterizes the electrical network at a reference time different from the milestone time during which the temperature of the portion of interest of the combustion vessel varies at the most ten percent (10%) from its milestone temperature, the step of evaluating including determining that the portion of interest of the combustion vessel has undergone a loss of material in the event that the interval between the reference time and the milestone time is greater than a predetermined interval.
  • Figure 1 is a schematic front plan view of an exemplary combustion vessel a condition of which is evaluated in accordance with the method of the present invention in the form of a power generating unit including a fossil fiiel-fired furnace;
  • Figure 2 is an enlarged front plan view of a portion of the water wall tubes of the fossil fuel-fired furnace shown in Figure 1 and showing, in simulated manner, an instantaneous resistance characteristic of an electrical network arranged with respect to the water wall tube portion at a reference or baseline time;
  • Figure 3 is an enlarged front plan view of the portion of the water wall tubes of the fossil fiiel-fired furnace shown in Figure 2 and showing, in simulated manner, an instantaneous resistance characteristic of the electrical network arranged with respect to the water wall tube portion at a milestone time.
  • FIG. 1 illustrates an exemplary power generating unit 10 having a fossil fuel fired combustion vessel in the form of a furnace 12 and additionally including a horizontal gas pass 14 and a back pass 16.
  • the furnace 12 has an fireside delimited by a plurality of water wall tubes 18 in which a heat exchange medium - namely, water - is circulated and which is converted into steam as a result of heating of the tubes 18 during the combustion of a fossil fuel such as, for example, coal, in the furnace 12.
  • the power generating unit 10 may include other conventional elements such as, for example, a turbine (not illustrated) for generating electricity under the motive action of steam passed thereover.
  • the horizontal gas pass 14 and the back pass 16 may comprise selected arrangements of economizers, superheaters, and reheaters.
  • a coal feed apparatus 20 is operable to feed coal to a feeder 22 which controls the rate of coal flow to a pulverizer 24.
  • Hot primary combustion air is also fed to the pulverizer 24 via a duct 25 and this air carries pulverized coal through and out of the pulverizer 24 and thereafter through coal pipes 26 to several groups of coal nozzles 28.
  • Each group of coal nozzles 28 is mounted in a respective tangential firing windbox 30 which also each support a group of secondary air nozzles 32.
  • the windboxes 30 introduce controlled flows of air and pulverized coal into the fireside of the furnace 12 to effect the formation therein of a rotating fireball.
  • the rotating fireball is a combustion process of the type which results in the release of a material which contributes to depositions on the fireside surfaces of the water wall tubes 18 - namely, carbon based combustion byproduct is released which builds up as slag on the fireside surfaces of the water wall tubes 18.
  • Figure 2 is a schematic representation of an electrical network 34 arranged relative to a portion of interest 36 of a fireside surface of several of the water wall tubes 18.
  • the electrical network 34 may be simulated as a plurality of resistors 38 arranged in series/parallel combination.
  • the resistors 38 are of equal value.
  • any selected portion of a metal tube can be regarded as a resistor.
  • each attachment pin of the type typically employed in the assembly of a series of water wall tubes together into a wall panel may be viewed as a lead or electrode through which current can be imposed with any selected group of adjacent pins being deemed as an electrical network such as the electrical network 34 from which electrical resistance can be measured when a current is imposed or impressed through one selected pin as an input and grounded through another selected pin as a ground.
  • the method is generally implemented by imposing one or more current patterns through leads or electrodes forming the electrical network 34, in a prescribed manner which will be described in more detail shortly, detecting a characteristic of the electrical network 34 - namely, voltage measurements corresponding to each imposed current, and evaluating a condition of the furnace 12 based upon the detected characteristic of the electrical network 34.
  • Each iteration of imposing a current on the electrical network 34 is accomplished by iteratively connecting one or more selected electrodes or leads to a voltage source 40 and connecting one or more other selected electrodes or leads to a ground 42.
  • a voltmeter 44 is connected to a respective resistor node to measure the voltage in connection with each imposed current pattern.
  • Another type of data display device may be substituted for the voltmeter 44 and a data storage and manipulation device such as, for example, a microprocessor 46, may be substituted for or coupled with the voltmeter 44.
  • the method includes the step of detecting, at one or more predetermined times, an instantaneous resistance characteristic of the electrical network 34.
  • one step of the method includes detecting, at a milestone time Ml, a milestone resistance characteristic MILECHAR of the electrical network 34.
  • the milestone resistance characteristic MILECHAR is detected by the voltmeter 44 at the milestone time Ml and the detected resistance characteristic is, additionally, displayed by the voltmeter and, if desired, transmitted to the microprocessor 46 for storage and manipulation thereby.
  • the portion 36 of the furnace 12 is characterized by an instantaneous temperature at the time of each detection of a resistance characteristic; for example, the portion 36 is characterized by a milestone temperature TEMPI at the milestone time Ml.
  • the method also includes the step of evaluating the milestone resistance characteristic MILECHAR with respect to a reference resistance characteristic REFCHAR of the electrical network 34.
  • the reference resistance characteristic REFCHAR characterizes the electrical network 34 at a reference or baseline time REFTIME different from the milestone time Ml during which the instantaneous temperature of the portion 36 of the water wall tubes 18 is different than its milestone temperature TEMPI.
  • the step of evaluating including evaluating at least one of: (a) the interval between the reference time REFTIME and the milestone time Ml and (b) a variation property of the milestone resistance characteristic MILECHAR and the reference resistance characteristic REFCHAR with respect to each other.
  • the variation property of the milestone resistance characteristic MELECHAR and the reference resistance characteristic REFCHAR with respect to each other may be either a property in which there is no variation between the milestone resistance characteristic MILECHAR and the reference resistance characteristic REFCHAR (i.e., the resistance characteristics are equal to one another) or a property in which there is a variation between the milestone resistance characteristic MILECHAR and the reference resistance characteristic REFCHAR.
  • the step of evaluating may include, in one variation of the method of the present invention, determining that a condition of slagging exists in portion 36 of the water wall tubes 18 in the event that: (1) the interval between the reference time REFTIME and the milestone time Ml is less than a predetermined magnitude and (2) a variation greater than a predetermined magnitude exists between the reference resistance characteristic REFCHAR and the milestone resistance characteristic MILECHAR.
  • This determination capitalizes on the premise that a change in resistance within a relatively short term (i.e., within an interval between the reference time REFTIME and the milestone time Ml less than a predetermined magnitude) as well as a heat flux of at least a minimum magnitude (i.e., a variation greater than a predetermined magnitude between the reference characteristic REFCHAR and the milestone resistance characteristic MILECHAR) signifies the existence of slagging.
  • the evaluating step may determine that a condition of an internal build up of material in the interior of the tubes exists in the event that: (1) the interval between the reference time REFTIME and the milestone time Ml is greater than a predetermined magnitude and (2) a variation greater than a predetermined magnitude exists between the reference resistance characteristic REFCHAR and the milestone resistance characteristic MILECHAR.
  • the step of evaluating the detected characteristic of the portion 36 of the water wall tubes 18 can include evaluating the milestone resistance characteristic MILECHAR with respect to the reference resistance characteristic REFCHAR with the reference time REFTIME at which the reference resistance characteristic REFCHAR is measured being selected such that the temperature of the portion 36 of the water wall tubes 18 at this time varies at the most ten percent (10%) from its milestone temperature TEMPI existing at the milestone time Ml.
  • the step of evaluating includes determining that the portion 36 of the water wall tubes 18 has undergone a loss of material in the event that the interval between the reference time REFTIME and the milestone time Ml is greater than a predetermined interval.
  • metal loss in a tube is a relatively long term change (i.e., the interval between the reference time REFTIME and the milestone time Ml is greater than a predetermined interval) which is detectable under uniform or substantially uniform heat flux conditions (i.e., the temperature of the portion 36 of the water wall tubes 18 varies at the most ten percent ( 10%) from its milestone temperature TEMP 1 ).
  • FIGs 2 and 3 Reference is made to Figures 2 and 3 as an illustration of the operation of the electrical network 34 and the associated components of the system of the present invention.
  • a current is imposed by the voltage source 40 at a selected electrode on the left hand side of the electrical network 34.
  • Another selected electrode, in the lower right hand corner of the electrical network 34 is connected to the ground 42.
  • the voltmeter 44 is coupled to yet another selected electrode and detects a reference resistance characteristic REFCHAR having a value of 8.055 volts. It is assumed in this illustration of the operation of the electrical network 34 that the portion 36 of the water wall tubes 18 has an instantaneous temperature of a determinate value at the respective reference or baseline time REFTIME.
  • the difference between the respective reference resistance characteristic REFCHAR and the milestone resistance characteristic MILECHAR is a decrease in the voltage of four (4) millivolts (a decrease of 0.05% in the detected voltage of the electrical network 34).
  • the increase in resistance at the one particular resistor 38 may be attributable, for example, to a metal loss of a water wall tube at or proximate to the one particular resistor 38.
  • the exemplary implementation of one variation of the method of the present invention just described thus illustrates that the method of the present invention can be implemented in a combustion vessel which includes a waterwall having a plurality of tubes for circulation therethrough of a heat transfer medium with the specific implementation that the step of evaluating includes determining that a condition of wastage of the waterwall exists in the event that: (1) the variation between the temperature at the reference time and the temperature at the milestone time is no greater than a maximum variation and (2) a variation exists between the reference resistance characteristic and the milestone resistance characteristic.

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  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Immunology (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Environmental Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Ecology (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention concerne un procédé et un système d'évaluation de l'état d'une surface de transfert thermique dans une cuve de combustion (12) exposée à des dépôts de matière, ladite matière étant produit par combustion d'un combustible dans la cuve de combustion (12) au cours d'un processus de combustion. Ledit procédé consiste à appliquer un courant sur une partie concernée (36) d'une surface côté combustion d'une pluralité des tubes d'écran d'eau de transfert thermique de manière à former un réseau électrique (34), et à détecter la tension correspondante et par conséquent la résistance instantanée du réseau électrique. Ledit procédé consiste par ailleurs à déterminer la résistance du réseau électrique (34) sur la base de la ou des fuites détectées de matière des écrans d'eau, du colmatage des écrans d'eau par dépôt extérieur de boues ou de cendres volatiles, ou de l'accumulation intérieure de matière.
EP00938186A 2000-06-06 2000-06-06 Controle du colmatage ou de la fuite de matiere de tubes de transfert thermique dans une cuve de combustion par mesures de resistance Ceased EP1287309A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2000/015580 WO2001094876A1 (fr) 2000-06-06 2000-06-06 Controle du colmatage ou de la fuite de matiere de tubes de transfert thermique dans une cuve de combustion par mesures de resistance

Publications (1)

Publication Number Publication Date
EP1287309A1 true EP1287309A1 (fr) 2003-03-05

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Family Applications (1)

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EP00938186A Ceased EP1287309A1 (fr) 2000-06-06 2000-06-06 Controle du colmatage ou de la fuite de matiere de tubes de transfert thermique dans une cuve de combustion par mesures de resistance

Country Status (3)

Country Link
EP (1) EP1287309A1 (fr)
AU (1) AU2000253263A1 (fr)
WO (1) WO2001094876A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6750660B2 (en) * 2001-09-12 2004-06-15 Alstom Technology Ltd Apparatus for evaluating data representing the electrical characteristics of a combustion vessel
FR2932886B1 (fr) * 2008-06-18 2014-09-19 Electricite De France Procede et dispositif pour la detection et/ou la mesure d'encrassement dans des echangeurs
FR3060741B1 (fr) 2016-12-21 2018-12-14 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif et procede d'evaluation d'au moins une condition de fonctionnement d'un echangeur de chaleur
FR3060730B1 (fr) 2016-12-21 2018-12-14 Commissariat A L'energie Atomique Et Aux Energies Alternatives Systeme et procede d'evaluation d'au moins une condition de fonctionnement d'un echangeur de chaleur
FR3069321B1 (fr) 2017-07-24 2020-07-10 Commissariat A L'energie Atomique Et Aux Energies Alternatives Systeme et procede d'evaluation d'au moins une condition de fonctionnement d'un echangeur de chaleur

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1895643A (en) * 1929-03-05 1933-01-31 Standard Oil Co California Method of and apparatus for measuring the thickness of metal
SE320676B (fr) * 1968-03-14 1970-02-16 Aka Ab Apparatkemiska
CA968851A (en) * 1972-04-20 1975-06-03 Universal Oil Products Company Fouling measuring device
US4048558A (en) * 1975-08-06 1977-09-13 Clark Goodman Method and apparatus for detecting metal failures in situ
US4982154A (en) * 1990-03-29 1991-01-01 General Electric Company Method of engagement of electrical contacts to pipe members
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
US5486767A (en) * 1994-03-03 1996-01-23 General Electric Company Method and system for detecting defects in pipes or other structures

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0194876A1 *

Also Published As

Publication number Publication date
WO2001094876A1 (fr) 2001-12-13
AU2000253263A1 (en) 2001-12-17

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