Model ZR22G, ZR402G Direct in-situ Separate Type Zirconia ... · • For the Zirconia cell, which is a key component of zirconia oxygen analyzers, a zirconia element and platinum

TechnicalInformation

Contents1. Overview..................................................................................................22. MeasurementPrincipleofZirconiaOxygenAnalyzers......................33. System Configuration............................................................................5

3.1 System Configuration Using a General-purpose Detector..........................53.2 System Configuration Using a High-temperature Detector.........................7

4. ZR22G Detector Construction and Features.......................................94.1 General-purpose Detector Construction......................................................104.2 High-temperature Detector Construction.....................................................114.3 Pressure Compensation Method...................................................................12

5. ZR402G Converter Functions and Features......................................135.1 Human Machine Interface (HMI)....................................................................13

5.1.1 BasicPanelandTouchPanelSwitch.............................................................. 135.1.2 DisplayConfiguration(forOxygenAnalyzer).................................................. 155.1.3 TrendGraphDisplay....................................................................................... 165.1.4 Detailed-dataDisplay...................................................................................... 175.1.5 Execution/SetupDisplay................................................................................. 21

5.2 Output Functions............................................................................................245.2.1 CurrentOutput................................................................................................. 245.2.2 ContactOutput................................................................................................ 25

5.3 OxygenConcentrationAlarms......................................................................275.3.1 AlarmOutputActions....................................................................................... 275.3.2 SettingAlarms................................................................................................. 28

6. Calibration.............................................................................................296.1 CalibrationOverview.......................................................................................296.2 Calibration Gas................................................................................................296.3 Two-point Calibration......................................................................................306.4 One-point Calibration......................................................................................306.5 Calibration Modes...........................................................................................316.6 SettingtheCalibrationTime...........................................................................31

7. Blow Back Function.............................................................................327.1 Blow Back Modes............................................................................................327.2 BlowBackOperations....................................................................................32

8. Directions for Use.................................................................................338.1 Effect of Coexisting Combustible Gases.....................................................338.2 Effect of Humidity in Reference Gas (Air).....................................................338.3 Precautions When Shutting Down a Furnace or Boiler..............................338.4 Dry Gas Base and Wet Gas Base...................................................................348.5 In Case Equipment is Turned On and Off Frequently..................................34

Revision History............................................................................................35

Model ZR22G, ZR402GDirect in-situSeparateTypeZirconiaOxygenAnalyzers(Hardware Edition)

TI11M12A01-03E1stEdition:Dec.2010(YK)

TI 11M12A01-03E

YokogawaElectricCorporation2-9-32,Nakacho,Musashino-shi,Tokyo,180-8750JapanTel.:81-422-52-5617 Fax.:81-422-52-6792

TI11M12A01-03E

22 1.Overview

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1. OverviewOxygenconcentrationiswidelymeasuredforthesakeofconservingenergy,preventingairpollution,controllingquality,andsoforth.Therearemanytypesofoxygenanalyzerswhichusevariousprinciplesofmeasurement.Zirconiaoxygenanalyzers,whichcanmeasuretheoxygenconcentrationinhigh-temperaturegasesdirectly,areoptimalforcombustionmanagementandcontrol,etc.incombustionequipmentandareusedinmanyindustriessuchasiron-andsteelmaking,electricpower,oilandpetrochemicals,chemicals,ceramic,paperandpulp,andtextiles.TheZR22G/ZR402GSeparateTypeZirconiaOxygenAnalyzershavethefollowingfeatures:• Ageneral-purposedetectorcandirectlymeasuregasofupto700ºC.Moreover,when

combinedwiththehigh-temperatureprobeadapter,itcanmeasuregasofupto1400ºC.• FortheZirconiacell,whichisakeycomponentofzirconiaoxygenanalyzers,azirconia

elementandplatinumelectrodesaremolecularlybondedbyamethoddevelopedbyYokogawa.Therefore,thezirconiasensorcandeliverconsistentmeasurementsforalongperiodwithouttheelectrodebeingpeeledoff.

• Theheaterassemblyusedtoheatupthezirconiacellisconstructedsothatitcanbereplacedinthefield.Evenifawireintheheaterbreaks,theheatercanbeeasilyreplacedinthefield.

• Theconverterfeaturesalargeliquid-crystaldisplaythatiseasytoseeandread.• Ahigh-resolutiongraphicdisplayisavailable,andtrendgraphdisplayofupto150minis

possible.• Atouchpanelisusedforoperations,allowinginformationtobeeasilyreadoutandsetup.• Operationsareperformedinteractivelywiththeoperationdisplay,sotheInstructionManual

isnotneededindailyoperations.• Duringcalibration,thesensor(cell)responsetime,internalresistancevalue,zerocalibration

factor,spancollectionfactor,etc.arecheckedandthedataareevaluatedcomprehensively.Thisallowstheremaininglifeofthecelltobepredicted.

• Twocurrentoutputs(4–20mA)andfourSPDTrelaycontactoutputsareavailable.Measurementdata,alarms,errors,etc.canbeoutput.

Thistechnicalinformationdocument(TI11M12A01-03E)isintendedtohelpusersunderstandandmakethebestuseofthesefeaturesoftheZR22G/ZR402GSeparateTypeZirconiaOxygenAnalyzers.Fordescriptionsoftypicalapplications,seethefollowingapplicationeditionofthistechnicalinformationdocument:ZR22G,ZR402GSeparateTypeZirconiaOxygenAnalyzers(ApplicationEdition)(TI11M12A01-01E)

TI11M12A01-03E

32.MeasurementPrincipleofZirconiaOxygenAnalyzers 3

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2. MeasurementPrincipleofZirconiaOxygenAnalyzersAsolidelectrolytesuchaszirconiacanconductoxygenionsathightemperature.AsshowninFigure2.1,whenazirconiaelementwithplatinumelectrodesbondedtobothsidesofitisheatedupincontactwithgaseshavingdifferentpartial-oxygenpressuresoneitherside,theelementactsasaconcentrationcell.Inotherwords,theelectrodeincontactwiththegaswithahigherpartial-oxygenpressureactsasanegativeelectrode.Asthegascomesincontactwiththezirconiaelementinthisnegativeelectrode,oxygenmoleculesinthegasacquireelectronsandbecomeoxygenions.Movinginthezirconiaelement,theyeventuallyarriveatthepositiveelectrodeontheoppositeside.There,theelectronsarereleasedandtheionsreturntooxygenmoleculesbythefollowingprocess: Negativeelectrode:O2+4e→2O2-

Positiveelectrode:2O2-→O2+4eBythisreaction,anelectromotiveforceisgeneratedbetweenthetwoelectrodesgovernedbyNernst’sequation:

nF PA

E = - ln ···················· (1)RT PX

where,R: Gasconstant n: 4 F: Faraday’sconstant T: Absolutetemperature Px: Oxygenconcentrationinagas(measurementgas)incontactwiththe

positiveelectrode(%) PA: Oxygenconcentrationinagas(referenceair)incontactwiththenegative

electrode(%)Becausethesensor(zirconiaelement)oftheZR22GDetectorisheatedupto750ºC,equation(1)becomes:

PA

E = -50.74 log ······················ (2)PX

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Reference airPA Electrode(negative)

Zirconia element

Electrode (positive)PX

Measurement gas

Figure 2.1 Schematic diagram of measurement principle

TI11M12A01-03E

44 2.MeasurementPrincipleofZirconiaOxygenAnalyzers

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Figure2.2showstheprincipleconstructionoftheZR22GDetector.

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Zirconia element

Measurementgas

Probe

Electrodes

Reference gas

VoltmeterE

Figure 2.2 Principle construction of the ZR22G Detector

Whenairisusedasareferencegasonthenegativeelectrodeside,therelationshipbetweentheoxygenconcentrationofthemeasurementgasandtheelectromotiveforceofthesensor(=cell)isasshowninFigure2.3.TherelationshipbetweentheoxygenconcentrationandtheelectromotiveforceofthecellinFigure2.3isonlytheoretical.Usually,inpractice,asensorshowsaslightdeviationfromthetheoreticalvalue;thisdeviationiscorrectedbyconductingcalibrationusingcalibrationgas.Fordetailsofcalibration,seechapter6,“Calibration.”

0.1 0.5 1 5 10 21.0 50 100

120

100

80

60

40

20

0

-20

-40

0.51 % O2, 81.92 mV (Zero origin of calibration)

21.0 % O2, 0 mV(Span origin of calibration)

Oxygen concentration (vol% O2) F0203.ai

Sen

sor (

cell)

vol

tage

(mV

)

Figure 2.3 Oxygen concentration in measurement gas vs. sensor (cell) voltage (on the basis of 21.0% O2)

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53. System Configuration 5

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3. System ConfigurationThesystemconfigurationofzirconiaoxygenanalyzersisdividedintotwomaintypes,thoseusingeitherageneral-purposedetector(measurementgastemperatureof700ºCandbelow)orthoseusingahigh-temperaturedetector(measurementgastemperatureof1400ºCandbelow).Moreover,eachofthesetypesisfurtherdividedintothreesubtypes,givingsixtypesintotal.

Table 3.1 Types of System Configuration

SystemTypeNo. Detector Calibration Method RemarksL1 General-

purposetype

Simpletype Thestandardgasunitisused.L2 Generaltype(manual) Instrumentationairandzerogas

cylinderareused.L3 Generaltype(automatic)H1 High-

temperaturetype

Simpletype Thestandardgasunitisused.H2 Generaltype(manual) Instrumentationairandzerogas

cylinderareused.H3 Generaltype(automatic)

Therearetwomethodsoffeedinginreferenceair:oneistofeedinairnearthedetectorbynaturalconvectionandtheotheristouseinstrumentair.Themethodofusingairneartheinstrumentissimplebutthereisaproblemasdescribedbelow,soinstrumentairshouldbeusedifitisavailable.Incaseofusingnaturalconvection:Measurementmaybeaffectedbythehumidityinthe

airthatisfedin.Alargevariationinhumiditycausesameasurementerror,socareisrequired.

Incaseofusinginstrumentair:Airthathasbeendehumidifiedatadewpointtemperatureof−20ºCorlessandfromwhichoilmistanddusthavebeenremovedshouldbeused.

3.1 System Configuration Using a General-purpose Detector

(1) Type: L1 (simple measurement type)Thisisthesimplestsystemconsistingofadetectorandaconverter.Thissystemcanbeimplementedformonitoringoxygenconcentrationinthecombustiongasesofapackageboiler.Nopipingisrequiredforthereferencegas(air)whichisfedinattheinstallationsite.ThehandyZO21Sstandardgasunitisusedforcalibration.

EXA ZR402G

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Model ZR22G Detector

Model ZR402G Converter

Stop valve

Calibration gas

Model ZO21S standard gas unit

100 to240 V AC

Contact inputAnalog output, contact output

Signal(6-core shield cable)

Heater (2-core)

Figure 3.1 System configuration diagram for type L1

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66 3. System Configuration

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(2) Type: L2 (without automatic calibration)Thissystemisformonitoringandcontrollingoxygenconcentrationinthecombustiongasesofalarge-sizeboilerorheatingfurnace.Clean(dry)air(21%O2)isusedasthereferencegasandthespangasforcalibration.Zerogasisfedinfromacylinderduringcalibration.ThegasflowiscontrolledbytheZA8Fflowsettingunit(formanualvalveoperation).

EXA ZR402G


Stop valve or check valve

Model ZA8F flow setting unit

Model ZR22G Detector

100 to240 V AC

Air set

Instrument airCalibration gas

Reference gasFlowmeter Needle valve

Zero gas cylinder

Span gas



Heater (2-core)

Reducing valve

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(3) Type: L3 (with automatic calibration)Thissystemrepresentstypicalapplicationsinlargeboilersandheatingfurnaces,wherethereisaneedtomonitorandcontroloxygenconcentration.Thereferencegasandcalibration-timespangasare(clean,dry)instrumentair.Zerogasissuppliedfromagascylinder.ThissystemusestheZR40Hautocalibrationunit,withauto-switchingofthecalibrationgas.A“combustiblegasdetected”contactinputturnsoffpowertotheheater.There’salsocontactoutputfromtheconverterthatcanbeusedtooperateapurgegasvalvetosupplyairtothesensor.

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EXA ZR402G

Model ZR22G DetectorModel ZR402G Converter


Heater (2-core)

Reference gas

Calibration gas

Flowmeter Needlevalve

Zero gas cylinder

100 to 240 V ACCheck valve

Model ZR40H automatic calibration unit


Instrument air

Reducingvalve

Solenoidvalve

Air set


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73. System Configuration 7

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3.2 System Configuration Using a High-temperature Detector

(1) Type: H1 (simple measurement type)Thisisthesimplestsystemconfigurationforhigh-temperatureapplicationsandisusedforapackageboiler,etc.Forthereferenceair,airneartheinstallationsiteisfedin.Calibrationisdonemanuallyandzerogasandspangas(air)areintroducedtothedetectorviatheZO21Sstandardgasunit.

EXA ZR402G

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Calibration gas

Stopvalve

Model ZO21S standard gas unit

100 to240 V AC

Contact inputAnalog output,contact output


Supply air (150 kPa)

Needle valve

Ejector assembly

Pressure gauge assembly

Heater (2-core)

Model ZR22G-015 high-temperature detector

Model ZO21P-H high-temperatureprobe adapter

Measurement gas

Figure 3.4 System configuration diagram for type H1

(2) Type: H2 (without automatic calibration)Thissystemisforcontrollingandmeasuringoxygenconcentrationwithhighaccuracyinalargeboilerorheatingfurnace.Thereferencegasusesinstrumentair.Calibrationisdonemanually,andzerogas(fromacylinder)andspangas(instrumentair)arefedviatheZA8Fflowsettingunit.

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EXA ZR402G


Model ZA8F flow setting unit

100 to240 V AC

Air set

Instrument airCalibration gas

CheckvalveorStopvalve

Reducing valve

Reference gasFlowmeter Needle valve

Zero gas cylinder

Span gas



Heater (2-core)


Needle valve

Ejector assembly




Measurement gas


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3. System Configuration

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(3) Type: H3 (with automatic calibration)Thissystemisforcontrollingandmeasuringoxygenconcentrationwithhighaccuracyinalargeboilerorheatingfurnace.Thereferencegasusesinstrumentair.Calibrationisperformedbyoperatingtheautomaticcalibrationunitbasedoncommandsfromtheconverter.

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EXA ZR402G



Needle valve

Ejector assembly





Heater (2-core)

Reference gas

Calibration gas

Flowmeter Needlevalve

Zero gas cylinder

100 to 240 V ACCheckvalve

Model ZR40H automatic calibration unit


Instrument air

Reducingvalve

Air set

Solenoid valve

Measurement gas


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94. ZR22G Detector Construction and Features 9

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4. ZR22G Detector Construction and FeaturesTheZR22GZirconiaOxygenAnalyzerDetectorcanmeasuregasofupto700ºCdirectly.Ifgaswithtemperatureshigherthan700ºCneedstobemeasured,thehigh-temperatureprobeadaptercanbeusedtomeasuregasofupto1400ºC.TheZR22GDetectorhasthefollowingfeatures:• Thezirconiaelementandplatinumelectrodesaremolecularlybondedbyamethod

developedbyYokogawa,whicheliminatestheriskofpeeling. Thankstoaspecialcoating,theplatinumelectrodesarealsoprotectedfromdeterioration

causedbythemeasurementgasandarenotaffectedbySO2orNOXcontainedinthemeasurementgas.Thisallowsthedetectortoperformconsistentlyforalongperiod.

• Becausethezirconiacellusesaleadlesselectrodeconstructionthankstofull-peripheralcontactusingnichromewirecoil,thereisnoriskofwirebreakageandthecellcanbeeasilyreplaced.

• Theheaterassemblyusedtoheatupthezirconiaelementisconstructedsothatitcanbereplacedinthefield.Evenifawireintheheaterbreaks,theheaterassemblycanbeeasilyreplaced.

Full-peripheral contact is provided here using nichrome wire coil.

Platinum electrode using Yokogawa’smolecular bonding technique F0401.ai

Figure 4.1 Appearance of the zirconia sensor

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1010 4. ZR22G Detector Construction and Features

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4.1 General-purpose Detector ConstructionFigure4.2showsthepartnamesandfunctionsofthegeneral-purposedetector.Thesensor(zirconiacell)canbeeasilyreplacedbysimplyremovingfourbolts.Thefilterattachedatthefrontofthesensorisalarge-meshwirenetthatpreventslargedustparticlesfromenteringthesensor.

Terminal boxJIS C 0920 splash-proof type equivalent to IP44D orJIS C 0920 waterproof type equivalent to NEMA 4X/IP66(Achieved when the cable entry is completely sealed with a cable gland in the recirculation pressure compensated version)

ProbeThis part is inserted in the furnace.Length is selectable from 0.4, 0.7, 1.0, 1.5, 2.0, 2.5, 3.0 m,3.6, 4.2, 4.8 and 5.4 m

FlangeUsed to mount the detector.Selectable from JIS, ANSI or DIN standard models

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Bolt

Washer

Pipe support U-shaped pipe

Metal O-ring

Dust filter mounting screw

Sensor (cell)

Filter

Contact

Screw

Probe

Calibration gas pipe opening

Figure 4.2 Part names and functions of general-purpose detector (standard type)

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114. ZR22G Detector Construction and Features 11

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4.2 High-temperature Detector ConstructionFigure4.3showsthepartnamesandfunctionsofthehigh-temperaturedetector.Thedetectorconstructionisthesameasthatofthegeneral-purposedetectornotedabove,buttheflangesizeisdifferent.Forthehigh-temperatureprobeadapter,twotypesofprobematerialsareprovided:SUS310Sandsiliconcarbide(SiC).TheSUS310Sprobeadapterisusedtomeasuregasesatupto800ºC,whilethesiliconcarbide(SiC)probeadapterisforgasesupto1400ºC.

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Sample gas outletWhen a negative measurement gas pressure is used, connect the auxiliary ejector assembly.When the measurement gas is high-temperature and high-pressure and does not fall below 700ºC, connect a throttle valve (e.g. a needle valve).

FlangeSelectable from JIS, ANSI or DIN standard models

Separate Type High-temperature Detector (ZR22G-015)When the temperature of the measurement gas is between 700 and 1400ºC, mount the detector with a ZO21P-H probe adapter. The construction is the same as that of the general-purpose detector (except the flange size).The probe length is 15 cm.

High-temperature Probe Adapter (ZO21P-H)The probe is made of either SUS 310S or silicon carbide (SiC).The probe length is either 1.0 m or 1.5 m.When using an SiC probe, mount it vertically downward.

Figure 4.3 Part names and functions of the high-temperature detector

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1212 4. ZR22G Detector Construction and Features

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4.3 Pressure Compensation MethodIfthein-furnacepressureishighortherearevariationsinthein-furnacepressure,thepressurebalancebetweentheinsideofthefurnaceandthereferenceairislost,makingitdifficulttomeasuretheoxygenconcentrationaccurately.Inthiscase,thedetector’spressurecompensationfunctioncanbeusedtoreturnthereferenceairtothefurnacetomaintainthepressurebalancebetweentheinsideofthefurnaceandthereferenceairside.Thisenablesreliablemeasurementstobemade.Thisfunctionallowsin-furnacepressuresofupto250kPatobemeasured.

Furnace inside

Calibrationgas pipe

Zirconia cell

Heater

Reference air pipeReference air inlet

Calibration gas inlet

Reference air

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Figure 4.4 Pressure compensation method

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135. ZR402G Converter Functions and Features 13

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5. ZR402G Converter Functions and Features

5.1 Human Machine Interface (HMI)• Equippedwithaback-litlargedisplayunitthatiseasytoseeandread.• High-resolutiongraphicdisplay.Upto150minutesoftrendgraphcanbedisplayed.• Thetouchpanelallowsinformationtobeeasilyreadandsetup.• Interactiveoperationsalongwithoperationdisplay,eliminatingtheneedforanInstruction

Manual.

5.1.1 Basic Panel and Touch Panel Switch

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Tag name display area

Primary value

Secondary value

Tertiary value

Switch display area

Alarm and error display area

Figure 5.1 Basic panel display

l Basic panel displayTagnamedisplayarea: Displaysthesettagname.Primarytotertiarydisplayitems: Displaystheselectediteminlargeletters(seeTable5.1).Secondaryandtertiarydisplayitems: Displaytheselecteditemsinsmallletters(seeTable5.1).Switchdisplayarea: Displaysswitchesandfunctionsselectedaccordingto

thepaneldisplay(seeFigure5.2).Alarmanderrordisplayarea: Displaysanerrorifanalarmorerroroccurs.Ifyou

touchthisarea,thedetailsoftheerrororalarmarethendisplayed.

Table 5.1 Display Items

Item Primaryvalue

Secondary & tertiaryvalues Display

Oxygenconcentration Oxygenconcentrationduringmeasurement

Airratio CurrentcomputedairratioMoisturequantity Moisturequantity(%H2O)intheexhaustgas

Output1item Oxygenconcentrationwiththeequipmentsetforoxygenanalyzer(See*1below.)

Output2item Oxygenconcentrationwiththeequipmentsetforoxygenanalyzer(See*1below.)

Currentoutput1 Currentvalueoutputfromanalogoutput1

Currentoutput2 Currentvalueoutputfromanalogoutput2

*1: Ifananalogoutputsmoothingconstantisset,theoxygenconcentrationdisplaythenincludesthesesettings.

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1414 5. ZR402G Converter Functions and Features

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l TouchPanelSwitchTheZR402Gusesatouchpanelthatcanbeoperatedbyjusttouchingtheswitchdisplay.Theswitchesdisplayedinthisareaandtheirfunctionsvarydependingonthepaneldisplay,allowingallswitchoperations.Figure5.2showsthetypesofswitchesandtheirfunctions.

Enter

Home key:Returns to the Execution/Setup display.

Reject key:Moves back to the previous display.

Cursor key:Moves the cursor down.

Graph display key:Displays a trend graph.

Alarm:Displayed if an alarm occurs.

Enter key:Used to confirm the input value or a selected item.

Setup key:Used to enter the Execution/Setup display.

Detailed-data key:Displays the analog input value.

Cursor:Points the cursor at the currently selected item.

Error:Displayed if an error occurs.

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Figure 5.2 Switch names and their functions

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5.1.2 Display Configuration (for Oxygen Analyzer)Figure5.3showsthedisplayconfiguration.ApasswordcanbeusedtoprotectthedisplayspositionedbelowtheExecution/Setupdisplay.

[Basic panel display]

[Detailed-data display] [Execution/Setupdisplay]

[Trend Graph display]

[Password Entry display]

Calibration execution

Returns to the Execution/Setupdisplay.

Blow back execution


Reset panel display


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Maintenancepanel display


Commissioning(Setup) display


Display setup Display item Trend graph Auto return time LanguageCalibration setup Mode Points Zero- and Span-gas conc. TimingBlow back setupmA-output loop checkContact check

mA-output setup mA-output1 mA-output2 Output heldAlarm setup Hysteresis Contact delay SetpointsContact setup Input contacts Output contactsOthers Clock Averaging Fuel setupPasswordsDefaults

Figure 5.3 Display configuration

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5.1.3 Trend Graph DisplayWhenthe keyispressedinthebasicpaneldisplay,thegraphdisplayshowingmeasuredvaluesonthetimeaxisappears.Thisdisplayisusefulforviewingthetrendofmeasuredvaluesorcheckingthestabilityofthereadingbyobservingtrenddataoftheoxygenconcentrationduringautomaticcalibration.

Figure 5.4 Trend Graph display

l Display of the Trend Graph DisplayTimeaxis(userselectable,1to150min)Measuredvalueaxis(userselectable)Tagnumber(usersettable)Currentlymeasuredvalue

l Sampling PeriodThisgraphallowstheplottingof60dataitemsononegraduationonthetimeaxis.So,ifyousetaten-secondsamplingperiod,onegraduationcorrespondsto600seconds(Figure5.5).Theallowablesamplingperiodsrangefrom1to30seconds.Ifyousetaone-secondsamplingperiod,theaxisoftheabscissasthencorrespondstofiveminutes.Ifyousetitto30seconds,theaxisoftheabscissasthencorrespondsto150minutes.

0.0 % O2

25.0 % O2

Upper limit set

Lower limit set

10 min/div.

Sampling period

60 data items

12.3 % O2

Currently measured value

Time per graduation, calculated by the set sampling period

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Figure 5.5 Sampling period

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l Measured Value AxisSettheupperandlowerlimitsofmeasuredvaluesonthey-axisofthegraph.Theallowablesettingsforbothupper-limitandlower-limitvaluesrangefrom0to100%O2.

5.1.4 Detailed-data DisplayTheDetailed-datadisplayisusedtodisplaythedetailedoperationdata.Therearetenpaneldisplaysforviewingdetaileddata.Thefollowingbrieflydescribetheoperationaldatadisplayedonthedetailed-datadisplay.

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Figure 5.6 Detailed-data display

(1) Span-gas and Zero-gas Correction RatiosTheseareusedtocheckfordegradationofthesensor(cell).IfthecorrectionratioisbeyondthelimitsasshowninFigure5.7,thesensorshouldnolongerbeused.Theseratiosarecalculatedasshownbelow.

21.0 p1 0.51

81.92ez

e1

es

0C

AB

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Cel

l ele

ctro

mot

ive

forc

e, m

V

Calibration curve before correction

Correctedcalibration curve(Theoreticalcalibration curve)

Previouszero-gas data

Zero origin

Span origin

Span-gas concentrationOxygen concentration (vol% O2)

Span correction factor = (C/A) x 100 (%) Correctable range: 0 ± 18%Zero-point correction factor = (B/A) x 100 (%) Correctable range: 100 ± 30%

Figure 5.7 Calculation of a two-point calibration curve and correction factors using zero and span gases

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(2) Response TimeThecell’sresponsetimeisobtainedintheprocedureshowninFigure5.8.Ifonlyeitherazero-pointorspancalibrationhasbeencarriedout,theresponsetimewillnotbemeasuredjustasitwillnotbemeasuredinmanualcalibration.Theresponsetimeisobtainedafterthecorrectedcalibrationcurvehasbeenfound.Theresponsetimeiscalculated,startingatthepointcorrespondingto10%oftheanalogoutputuptothepointat90%oftheanalogoutputspan.Thatis,thisresponsetimeisa10to90%response.

10% of analog output span

Five minutes maximum

mA

90%100%

Start calibrationTime

Calibrationcomplete

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Response time

Figure 5.8 Functional drawing of response time

(3) Robustness of a CellTherobustnessofacellisanindexforpredictingtheremaininglifeofasensorandisexpressedasoneoffourtimeperiodsduringwhichthecellmaystillbeused:(1)morethanoneyear(2)morethansixmonths(3)morethanthreemonths(4)lessthanonemonthTheabovefourtimeperiodsaretentativeandusedonlyforpreventivemaintenance,notforwarrantyoftheperformance.Thiscell’srobustnesscanbefoundbyacomprehensiveevaluationofdatainvolvingthecell’sresponsetimeandinternalresistanceandzerogasandspangasratios.

(4) Cell TemperatureThisindicatesthecell(sensor)temperature,usually750ºC,obtainablefromthe“thermoelectromotiveforce”and“coldjunctiontemperature”describedbelow.

(5) C. J. TemperatureThisindicatesthedetectorterminalboxtemperature,whichcompensatesforthecoldjunctiontemperatureforathermocouplemeasuringthecelltemperature.WhentheZR22GDetectorisused,themaximumC.J.temperaturewillbe150ºC.Iftheterminalboxtemperatureexceedsthis,takemeasures,forexample,sothattheterminalboxisnotexposedtoradiationtoreducethattemperature.ThemaximumC.J.temperaturevariesdependingonthetypeofdetector.

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(6) Cell VoltageThecell(sensor)voltagewillbeanindextodeterminetheamountofdegradationofthesensor.Thecellvoltagecorrespondstotheoxygenconcentrationcurrentlybeingmeasured.Iftheindicatedvoltageapproximatestheidealvalue(correspondingtothemeasuredoxygenconcentration),thesensorwillbeassumedtobenormal.Theidealvalueofthecellvoltage(E),whentheoxygenconcentrationmeasurementtemperatureiscontrolledat750°C.,maybeexpressedmathematicallyby: E = -50.74 log (Px/PA) [mV]

where,Px: Oxygenconcentrationinthemeasuredgas PA: Oxygenconcentrationinthereferencegas,(21%O2)Table5.2showsoxygenconcentrationversuscellvoltage.

Table 5.2 Oxygen Concentration Vs. Cell Voltage, (cell temperature: 750°C)

%O2 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9mV 117.83 102.56 93.62 87.28 82.36 78.35 74.95 72.01 69.41

%O2 1 2 3 4 5 6 7 8 9mV 67.09 51.82 42.88 36.54 31.62 27.61 24.21 21.27 18.67

%O2 10 21.0 30 40 50 60 70 80 90mV 16.35 0 -7.86 -14.2 -19.2 -23.1 -26.5 -29.5 -32.1

%O2 100mV -34.4

(7) Thermocouple VoltageThecell(sensor)temperatureismeasuredwithaTypeK(chromel-alumel)thermocouple.Thethermocouplecoldjunctionislocatedinthedetectorterminalbox.Thecelltemperatureandthethermocouplevoltage(includingthevoltagecorrespondingtothecoldjunctiontemperature)aredisplayed.

(8) Cold Junction Resistance (C. J. Voltage)TheZR22GDetectormeasuresthecoldjunctiontemperatureusinganRTD(Pt1000).

(9) Cell’s Internal ResistanceAnewcell(sensor)indicatesitsinternalresistanceof200Ωmaximum.Asthecelldegrades,sowillthecell’sinternalresistanceincrease.Thedegradationofthecellcannotbefoundonlybychangesincell’sinternalresistance,however.Thosechangesinthecell’sinternalresistancewillbeahinttoknowingthesensorisdegrading.Theupdatedvaluesobtainedduringthecalibrationaredisplayed.

(10) Software RevisionTherevision(number)ofthesoftwareinstalledintheZR402GConverterisdisplayed.

(11) Maximum Oxygen ConcentrationThemaximumoxygenconcentrationandthetimeofitsoccurrenceduringtheperiodspecifiedintheAveragingdisplayaredisplayed.Ifthesetupperiodelapses,themaximumoxygenconcentrationthathasbeendisplayedsofarwillbeclearedandanewmaximumoxygenconcentrationwillbedisplayed.Ifthesetupperiodoftimeischanged,thecurrentmaximumoxygenconcentrationwillbedisplayed.

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(12) Minimum Oxygen ConcentrationTheminimumoxygenconcentrationandthetimeofitsoccurrenceduringtheperiodspecifiedintheAveragingdisplayaredisplayed.Ifthesetupperiodelapses,theminimumoxygenconcentrationthathasbeendisplayedsofarwillbeclearedandanewminimumoxygenconcentrationwillbedisplayed.Ifthesetupperiodoftimeischanged,thecurrentminimumoxygenconcentrationwillbedisplayed.

(13) Average Oxygen ConcentrationTheaverageoxygenconcentrationduringtheperiodsoverwhichaveragevaluesarecalculatedthatisspecifiedintheAveragingdisplayisdisplayed.Ifthesetupperiodelapses,theaverageoxygenconcentrationthathasbeendisplayedsofarwillbeclearedandanewaverageoxygenconcentrationwillbedisplayed.Ifthesetupperiodoftimeischanged,thecurrentaverageoxygenconcentrationwillbedisplayed.

(14) Heater On-Time RatioTheprobesensorisheatedtoandmaintainedat750ºC.Whenthemeasuredgastemperatureishigh,theamountofheaterON-timedecreases.

(15) TimeThecurrentdateandtimearedisplayed.Thesearebackedupbythebuilt-inbatteriesafterthepowerisswitchedoff,sonoadjustmentisrequired.

(16) History of Calibration TimeThecalibration-conducteddatesandtimes,andspan-gasandzero-gasratiosforthepasttencalibrationsarestoredinmemory.

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5.1.5 Execution/Setup DisplayThisdisplayisusedtocalibrateormaintaintheequipmentorperformbasicsetup.Therearethreeexecutiondisplaysandtwodatasetupdisplays(fivedisplaysintotal).Theiroperationscanbeprotectedbyapassword.

l Basic Panel DisplayThisdisplayshowsthegeneralmeasurementstatus.

Whenthe keyispressed,thefollowingdisplayappears.

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Figure 5.9 Basic panel display

l Execution/Setup DisplaySelecttherequireditemfromamongtheitemsdisplayed.Forexample,ifyouwishtomakesetup,selectSetupusingthekeyandpressthe[Enter]key.

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Figure 5.10 Execution/Setup display

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(1) Execution displayl Calibration Execution Display

Thisistheexecutiondisplayforcalibration,andisusedtoperformmanualorsemi-automaticcalibration.

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Figure 5.11 Calibration execution display

l Blow back Execution DisplayThisdisplayisusedtoexecuteblowback.

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Figure 5.12 Blow back execution display

l Reset displayIfanerroroccurs,youcanresettheequipmentfromthisdisplayinthefollowingcases:(1)Error1–ifthecellvoltageisincorrect(2)Error2–ifatemperaturealarmoccurs(3)Error3–iftheA/Dconverterisdefective(4)Error4–ifanEEPROMwriteerroroccurs

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Figure 5.13 Reset display

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(2) Setup display

l Maintenance DisplayThisdisplayisusedtosetdataforequipmentmaintenanceormakealoopcheck,etc.

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Figure 5.14 Maintenance display

l Commissioning (Setup) DisplayThisdisplayisusedtosetuptheoperationdatasuchascurrentoutputsoralarms.

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Figure 5.15 Commissioning (Setup) display

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5.2 Output Functions5.2.1 CurrentOutput

TheZR402GZirconiaOxygenAnalyzerConverterhastwo4–20mADCcurrentoutputs.Theoutputrangeofmeasuredvalue(oxygenconcentration)canbearbitrarilysetfrom0to5inarangeof0to100vol%O2.Apartialrangecanalsobeset(theratiobetweenthemaximumandminimumvaluesshouldbe1.3ormore).Settingismadebyselecting“mA-outputsetup”intheCommissioning(Setup)displayshowninFigure5.15andthenchoosing“mA-output1”or“mA-output2”inthemA-outputsetupdisplay.

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Figure 5.16 mA-output setup display Figure 5.17 mA-output 1 range display

Thefollowingoutputfunctionscanalsobesetup.

l SettingOutputSmoothingConstantsIfameasuredvaluewhichisadverselyaffectedbyrapidchangesintheoxygenconcentrationofthemeasurementgasisusedasthebasisforcontrol,frequenton-offactionsoftheoutputmayresult.Toavoidthis,theconverterallowsoutputsmoothingconstantstobesetfrom0to255seconds,usingthemA-output1rangedisplayshowninFigure5.17.

l Output Hold SettingThe“outputhold”functionsholdananalogoutputsignalatthemeasuredvaluejustbeforeoccurrenceorapresetvalueduringtheequipment’swarm-uptimeorcalibrationorifanerrorarises.Outputs1and2cannotbesetindividually.Table5.3showstherelationshipbetweenindividualequipmentstatesandtheanalogoutputsthatcanberetained.

Table 5.3 Individual Equipment States and the Analog Outputs That Can Be Retained

Equipmentstate

Output holdvaluesavailable

During warm-up

Under maintenance

Under calibrationDuring blow back

Onerroroccurrence

4mA

20mA

Without hold feature

Retainsoutputfromjustbeforeoccurrence

Set value (2.4 to 21.6 mA)

:Theoutputholdfunctionsareavailable.

Tosettheoutputholdfunction,select“Setpresets”onthemA-outputsetupdisplay.ThiscausesthedisplayshowninFigure5.18toappear.

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Fromthisdisplay,selectthedesireditem.Figure5.19showsanexampleofselecting“Maintenance.”Thenthedesiredoutputstatuscanbeselected.

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Figure 5.18 mA-output presets display Figure 5.19 Example of mA-output presets

5.2.2 ContactOutputTherearefourcontactoutputs.Forcontactoutputs1to3,youcanselecteithernormallyenergizedornormallyde-energized.Settingitemscanalsobeselected.Table5.4showsalistofsettingitems.Contactoutput4isnormallyenergizedandthesettingitemisalsofixedto“Error.”Thesettingitemsandcontactactionsofcontactoutputs1to3arehandledasfollows:PresstheSetupkeyinthebasicpaneldisplaytodisplaytheExecution/SetupdisplayshowninFigure5.10andselect“Setup.”Thenselect“Contactsetup”intheCommissioning(Setup)displayshowninFigure5.15.TheContactsetupdisplayshowninFigure5.20appears.Inthisdisplay,select“Contactoutput1”to“Contactoutput3”tosetupindividualitems.

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Figure 5.20 Contact setup display Figure 5.21 Output contact 1 display

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Figure 5.22 Example display of setting Contact 1 Others

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Table5.4 ContactOutputSettings

Item to be selected DescriptionAlarmandErro

rSettings

High-high-limitalarmIf"high-highalarmON"isselected,contactoutputoccurswhenthehigh-high-limitalarmisissued.Todothis,itisrequired,inalarmsetup,thatthehigh-highalarmbesetonbeforehand.

High-limitalarmIf"highalarmON"isselected,contactoutputoccurswhenthehigh-limitalarmisprovided.Todothis,itisrequired,inalarmsetup,thatthehigh-limitalarmbesetonbeforehand.

Low-limitalarmIf"lowalarmON"isselected,contactoutputoccurswhenthelow-limitalarmisprovided.Todothis,itisrequired,inalarmsetup,thatthelow-limitalarmbesetonbeforehand.

Low-low-limitalarmIf"low-lowalarmON"isselected,contactoutputoccurswhenthelow-low-limitalarmisissued.Todothis,itisrequired,inalarmsetup,thatthelow-lowalarmbesetonbeforehand.

CalibrationcoefficientalarmIfcalibrationcoefficientalarmisON(enabled),thenwhenazero-calibrationcoefficientalarm(alarm6)orspancalibrationcoefficientalarm(alarm7)occursthencalibrationcoefficientalarmcontactoutputoccurs.

Startuppowerstabilizationtimeoutalarm

IfsetONthencontactoutputoccurswhenstartuppowerstabilizationtimeoutalarm(alarm8)occurs.

Error If"ErrorON"isselected,contactoutputoccurswhenanerrorresults.

Othersettings

Warm-up If"Warm-upON"isselected,contactoutputoccursduringwarm-up.Forthedefinitionofwarm-up.

Outputrangechange

If"RangeChangeON"isselected,contactoutputoccurs("answer-backsignaltoarangechangesignal")whilearangechangesignalisappliedtoacontactinput.Todothis,itisrequired,ininputcontactsetup,thattherangechangebeselectedbeforehand.

Calibration If"CalibrationON"isselected,contactoutputoccursduringcalibration.Forthedefinitionof"Duringcalibration,".

Maintenance If"MaintenanceON"isselected,contactoutputoccursduringmaintenance.Forthedefinitionof"Duringmaintenance,".

Blowback If"BlowbackON"isselected,contactoutputoccursduringblowback.Forthedefinitionof"Duringblowback,".

High-limittemperaturealarm Notsupportedbytheoxygenanalyzer.

Calibrationgaspress.low

If"Cal.gaspress.lowON"isselected,contactoutputoccurs("answer-backsignaltoacalibration-gaslow-pressuresignal")whenacalibration-gaslow-pressuresignalisappliedtothecontactinput.Todothis,itisrequired,ininputcontactsetup,that"Cal.gaspress.Low"beselectedbeforehand.

Processupset

If"Processupset"isselected,contactoutputoccurs("answer-backsignaltoaprocessupsetsignal)whentheprocessupsetsignalisappliedtothecontactinput.Todothis,itisrequired,ininputcontactsetup,that"processupset"beselectedbeforehand.

Note: Toprovideanalarmwithanoutputcontact,besuretomakeanalarmsetting. Whenusingcontactoutputasananswer-backsignalforaninputcontact,besuretomakeaninputcontact.

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5.3 OxygenConcentrationAlarmsTheanalyzerenablesfouralarms—high-high,high,low,andlow-lowalarms—tobesetfortheoxygenconcentration.Thesettingrangeis0to100%O2foranyalarm.

5.3.1 AlarmOutputActionsIfthemeasuredvaluesoftheoxygenconcentrationfluctuatebetweennormal(steadystate)valuesandthealarmsetting,alarm-outputsmaybefrequentlyissuedandcanceled.Toavoidthis,setanalarmdelayandhysteresisforalarmcancelingunderthealarmoutputconditions.Whenadelaytimeisset,analarmwillnotbeissuedsoquicklyevenifthemeasuredvaluediffersfromthesteady-stateandentersthealarmsetpointrange.Ifthemeasuredvalueremainswithinthealarmsetpointrangeforacertainperiodoftime(thepresetdelaytime),analarmwillbeissued.Ontheotherhand,therewillbeasimilardelayeachtimethemeasuredvaluereturnstothesteadystatefromthealarmsetpointrange(cancelingthealarmstatus).Ifhysteresisisset,alarmswillbecanceledwhenthemeasuredvalueislessthanorgreaterthanthepresethysteresisvalues.Ifboththedelaytimeandhysteresisareset,analarmwillbeissuedifthemeasuredvalueisinthealarmsetpointrangeandthedelaytimehaselapsed.Forthealarmtobereset(canceled),themeasuredvaluemustbebeyondthepresethysteresisvalueandthepresetdelaytimemusthaveelapsed.ThesealarmoutputactionsareshowninFigure5.23.

Delay time: 5 sec Delay time: 5 sec Delay time: 5 sec

7.5%High-limit

alarm setpoint5.5%

Oxygenconcentration

Alarm outputONOFF

Hysteresis: 2.0%

A B C DAlarm range

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Figure 5.23 Alarm output action

IntheexampleinFigure5.23,thehigh-limitalarmpointissetto7.5%O2,thedelaytimeissettofiveseconds,andhysteresisissetto2%O2.Alarmoutputactionsineachsectioninthefigureaboveareasfollows:Section“A”: Althoughtheoxygenconcentrationexceedsthehigh-limitalarmsetpoint,itfalls

belowthehigh-limitalarmsetpointbeforethepresetdelaytimeoffivesecondselapses.So,noalarmisissued.

Section“B”: Theoxygenconcentrationexceedsthehigh-limitalarmsetpointandthedelaytimeelapsesduringthatmeasurement.So,analarmisissued.

Section“C”: Althoughtheoxygenconcentrationfallsbelowthehysteresissetvalue,thevaluerisesagainandexceedsthehysteresissetvaluebeforethepresetdelaytimeelapses.So,thealarmisnotcanceled.

Section“D”: Theoxygenconcentrationfallsbelowthehysteresissetvalueandthepresetdelaytimeelapses,sothealarmiscanceled.

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5.3.2 SettingAlarmsTosetalarmsetpoints,hysteresis,anddelaytime,dothefollowing.PresstheSetupkeyinthebasicpaneldisplaytoshowtheExecution/SetupdisplayinFigure5.10andthenselect“Setup”.Thenselect“Alarmsetup”intheCommissioning(Setup)displayinFigure5.15toshowtheAlarmsetupdisplayinFigure5.24.Inthisdisplay,selecttherequireditemandmaketherespectivesettings.

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Figure 5.24 Alarm setup display Figure 5.25 Oxygen alarms display

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6. Calibration6.1 CalibrationOverview

Thesensor(cell)electromotiveforceofthezirconiaoxygenanalyzerisgovernedbyNernst’sequation(seechapter2,“MeasurementPrincipleofZirconiaOxygenAnalyzers”).Whenthesensorisheatedupto750ºCandairisusedasthereferencegas,therelationshipbetweentheoxygenconcentrationofthemeasurementgasandtheelectromotiveforceofthesensor(cell)isasshowninFigure6.1.However,thisrelationshipisonlytheoretical.Inpractice,thesensor(cell)usuallyshowsaslightdeviationfromthetheoreticalvalue.Moreover,thesensordeterioratesovertime,causingtheelectromotiveforcetochange.Therefore,itisnecessarytocalibrateusingcalibrationgastocorrectthedeviationfromthetheoreticalvalue.

0.1 0.5 1 5 10 21.0 50 100

120

100

80

60

40

20

0

-20

-40

0.51 % O2, 81.92 mV (Zero origin of calibration)

21.0 % O2, 0 mV(Span origin of calibration)

Oxygen concentration (vol% O2) F0203.ai

Sen

sor (

cell)

vol

tage

(mV

)

Figure 6.1 Relationship between oxygen concentration in measurement gas and cell’s electromotive force (on the basis of 21.0% O2)

6.2 Calibration GasAgaswithaknownoxygenconcentrationisusedforcalibration.Normalcalibrationisperformedusingtwodifferentgases:a“zerogas”oflowoxygenconcentrationandaspangasofhighoxygenconcentration(two-pointcalibration).Insomecases,onlyoneofthegasesneedstobeusedforcalibration.However,evenifonlyoneofthegasesisnormallyused,calibrationusingbothgasesshouldbedoneatleastonce.Thefollowinggases arenormallyusedforzerogasandspangas.•Zerogas: Oxygenconcentrationof0.95to1.0vol%O2withabalanceofnitrogengas(N2)•Spangas: Cleanair(atadew-pointtemperaturebelow−20ºCandfreeofoilymistordust

asininstrumentair)Note: Nitrogengas(N2)withanoxygenconcentrationof0%cannotbeusedaszerogas. Thisisbecause,asdescribedinthechapteronthemeasurementprinciple,thezirconiaoxygenanalyzerdetects,as

electromotiveforce(E),changesinthepartialoxygenpressure(PX)onthemeasurementsidewithrespecttothepartialoxygenpressure(PA)onthereferenceside.

Becausethiselectromotiveforce(E)islogarithmicallyproportionaltoPX/PA,ifPXis0%,theelectromotiveforcebecomesinfinite,disablingcalibration.Ingeneral,gasof1%O2isusedforcalibrationwithzerogas.

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6.3 Two-point CalibrationFigure6.2showsatwo-pointcalibrationusingtwogases:zeroandspangases.Cellelectromotiveforcesforaspangaswithanoxygenconcentrationp1andazerogaswithanoxygenconcentrationp2aremeasuredwhiledeterminingthecalibrationcurvepassingbetweenthesetwopoints.Theoxygenconcentrationofthemeasurementgasisdeterminedfromthiscalibrationcurve.Inaddition,thecalibrationcurvecorrectedbycalibrationiscomparedwiththetheoreticalcalibrationcurvefordeterminingthezero-pointcorrectionratiorepresentedbyB/Ax100(%)onthebasisofA,BandCshowninFigure6.2andaspancorrectionratioofC/Ax100(%).Ifthezero-pointcorrectionratioexceedstherangeof100±30%orthespancorrectionratiobecomeslargerthan0±18%,calibrationofthesensorbecomesimpossible.

21.0 p1 0.51

81.92ez

e1

e2

es

0C

AB

p2

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Cel

l ele

ctro

mot

ive

forc

e, m

V



(Span-gas concentration)

Oxygen concentration (vol% O2)(Zero-gas concentration)

Zero origin

Span origin

Zero-point correction factor = (B/A) × 100 (%) Correctable range: 100 ± 30%Span correction factor = (C/A) × 100 (%) Correctable range: 0 ±18%

Figure 6.2 Calculation of a Two-point Calibration Curve and Correction Factors using Zero and Span Gases

6.4 One-point CalibrationFigure6.3showsaone-pointcalibrationusingonlyaspangas.Inthiscase,onlythecellelectromotiveforceforaspangaswithoxygenconcentrationp1ismeasured.Thecellelectromotiveforceforthezerogasiscarriedoverfromapreviousmeasurementtoobtainthecalibrationcurve.Theprincipleofcalibrationusingonlyaspangasalsoappliestotheone-pointcalibrationmethodusingazerogasonly.Themethodsofobtainingthespancorrectionratioandzero-pointcorrectionratioarethesameasthoseoftwo-pointcalibration.

21.0 p1 0.51

81.92ez

e1

es

0C

AB

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Cel

l ele

ctro

mot

ive

forc

e, m

V



Previouszero-gas data

Zero origin

Span origin

Span-gas concentrationOxygen concentration (vol% O2)

Span correction factor = (C/A) x 100 (%) Correctable range: 0 ± 18%Zero-point correction factor = (B/A) x 100 (%) Correctable range: 100 ± 30%

Figure 6.3 Calculation of a One-point Calibration Curve and Correction Factors using a Span Gas

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6.5 Calibration ModesZirconiaoxygenanalyzersemploythefollowingthreeoperationmodesforcalibration.•Manualcalibration: Allowszeroandspancalibrations,oreitheronemanuallyinturn.•Semi-automaticcalibration: Letscalibrationstartwiththetouchpaneloracontactinput,and

undergoesaseriesofcalibrationoperationsfollowingpresetcalibrationperiodsandstabilizationtime.

•Automaticcalibration: Performscalibrationautomaticallyfollowingpresetcalibrationperiods.

6.6 SettingtheCalibrationTime(1) For manual calibration

Firstsettheoutputstabilizationtime.Thisindicatesthetimerequiredfromtheendofcalibrationtoenteringameasurementagain.Thistime,aftercalibration,themeasurementgasentersthesensortosetthetimeuntiltheoutputreturnstonormal.Theoutputremainsheldaftercompletingthecalibrationoperationuntiltheoutputstabilizationtimeelapses.Thecalibrationtimesetrangesfrom00minutes,00secondsto60minutes,59seconds.

(2) For semi-automatic calibrationSettheoutputstabilizationtimeandcalibrationtime.Thecalibrationtimeisthetimerequiredfromstartingtheflowofthecalibrationgastoreadingoutthemeasuredvalue.Thesetcalibrationtimeiszeroandspancalibrations.Thecalibrationtimesetrangesfrom00minutes,00secondsto60minutes,59seconds.Figure6.4showstherelationshipbetweenthecalibrationtimeandoutputstabilizationtime.

Calibration start (contact or switch input)

Span calibration (span-gas valve open)

Zero-point calibration (zero-gas valve open)

Analog output status

Calibration time

Calibration time

Stabilizationtime

Analog output remains held (when output remains held)

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Figure 6.4 Calibration and output stabilization time settings

(3) For automatic calibrationInadditiontotheaboveoutputstabilizationtimeandcalibrationtime,settheinterval,startdate,andstarttime.Intervalmeansthecalibrationinterval,rangingfrom000days,00hoursto255days,23hours.Setthefirstcalibrationday,andthestart-calibrationtime,respectively.

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7. Blow Back FunctionTheprobeeasilybecomescloggedifthesamplegascontainstoomuchdustsuchasinarecoveryboilerorcementkiln.Theblowbackfunctionisusedtoremovesuchdustwithairpressure.

7.1 Blow Back ModesThezirconiaoxygenanalyzeroffersthefollowingtwoblowbackmodes:

l Semi-automatic blow backInthismode,touchpaneloperationsorcontactinputsignalswillstartandperformblowbackoperationsaccordingtoapresetblowbacktimeandoutputstabilizationtime.

l AutomaticblowbackPerformsblowbackoperationsautomaticallyaccordingtoapresetinterval,blowbacktime,andoutputstabilizationtime.

7.2 BlowBackOperationsFigure7.1showsatimingchartfortheoperationofblowback.Toexecuteblowbackwithacontactinput,useacontactinputwithanON-timeperiodof1to11seconds.Onceblowbackstarts,acontactoutputopensandclosesat10secondintervalsduringthepresetblowbacktime.Aftertheblowbacktimeelapses,theanalogoutputremainsheldatthepresetstatusuntiltheholdtimeelapses.Asthehold(outputstabilization)time,setthetimeuntilthemeasuredgasisreturnedtothesensorandtheoutputreturnstothenormaloperatingconditions,aftercompletingblowbackoperations.

ON-time period of 1 to 11 seconds for the contact input

Blow back start(with contact input or touch panel operation)

Contact output(blow back switch)

Analog output

ON(for 10 seconds)

ON(for 10 seconds)

ON(for 10 seconds)OFF

(for 10 seconds) Hold time

Analog output remains held(with HOLD feature specified)

Blow back time

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Figure 7.1 Operation of blow back

•Blowbacktime: Canbesetfrom00min,00secto60min,59sec.•Holdtime(outputstabilizationtime):Canbesetfrom00min,00secto60min,59sec.

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8. Directions for UseToachieveaccuratemeasurementswithazirconiaoxygenanalyzer,thefollowingmustbeconsidered.

8.1 Effect of Coexisting Combustible GasesThesensor(zirconiaelement)isheatedto750ºCduringmeasurements.Iftheprocessgascontainscombustiblegasessuchascarbonmonoxide,hydrogen,andmethane,thesegasesburninthedetectorandconsumeoxygen,causingtheoxygenconcentrationmeasuredbytheoxygenanalyzertobesmallerthantheactualvalue.Therefore,zirconiaoxygenanalyzersshouldbeusedonlywhentheeffectofcoexistingcombustiblegasescanbeignoredorwhentheireffectonoxygenconcentrationcanbecorrected.Generally,exhaustgasesaftercombustionthatareemittedfromcombustionequipmentsuchasboilersandindustrialfurnaceshavebeencompletelyburned;thevolumeofcombustiblegasessuchascarbonmonoxideisverysmallincomparisonwithoxygen,andsotheirinfluencecanbeignored.However,iftheexcessairratioisextremelysmallorifcombustionisnon-uniform,causingcarbonmonoxidetobeproduced,careisrequired.

8.2 Effect of Humidity in Reference Gas (Air)Zirconiaoxygenanalyzersuseagaswhoseoxygenconcentrationisknownandalwaysconsistent,asthereferencegas.Ingeneral,airisusedasthereferencegas.Theoxygenconcentrationofdryairisconstantat20.95%;however,airgenerallycontainswatervapor,inwhichcasetheoxygenconcentrationvarieswithtemperatureandhumidity.Inzirconiaoxygenanalyzers,ameasurementerroriscausedifthetemperatureorhumidityofthereferencegas(air)variessignificantlybetweencalibrationandmeasurement.Wheninstrumentairisusedasthereferencegas,thiserrorcanbeignored,butifitcannotbeused,careisrequired.

8.3 Precautions When Shutting Down a Furnace orBoiler

Whenoperatinganinstrumentsuchasboilerorindustrialfurnaceisstoppedwiththezirconiaoxygenanalyzeroperation,moisturecancondensateonthesensorportionanddustsmaysticktoit.Ifoperationisrestartedinthiscondition,thesensorwhichisheatedupto750°Cfirmlyfixthedustsonitself.Consequently,thedustscanmakethesensorperformanceverylower.Ifalargeamountofwateriscondensed,thesensorcanbebrokenandneverreuseful.Topreventtheabovenonconformity,takethefollowingactionwhenstoppingoperation.(1)Ifpossible,keeponsupplyingthepowertoconverterandflowingreferenceairtothesensor.

Ifimpossibletodotheabove,removethedetector.(2)Ifunavoidablyimpossibletosupplythepowerandremovingthedetector,keeponfollowing

airat600ml/minintothecalibrationgaspipe.

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8.4 Dry Gas Base and Wet Gas BaseExhaustgasemittedbycombustionoffuelcontainswatervaporgeneratedbytheburningofhydrogeninthefuel.Whendirectlymeasuringgasesinafluewithazirconiaoxygenanalyzer,exhaustgascontainingmoistureismeasured.Valuesmeasuredundertheseconditionsarecalled“valuesbasedonawetgas.”Incontrast,foroxygenanalyzersthatsampleandmeasureexhaustgases,thesamplegastemperatureisloweredtonormaltemperatureintheprocessofbeingintroducedintotheanalyzerandmoisturethatwouldcondenseintowaterisalsoremovedfromthesamplegas.Valuesmeasuredafterremovingthemoistureinthiswayarecalled“valuesbasedonadrygas.”Whileavaluebasedonadrygasregardsthetotalgascompositionavailableaftermoistureremovalas100%,avaluebasedonawetgasassumesthatthegascompositionincludingwatervaporis100%.Therefore,theresultsdifferbetweenbothmeasurementtypesevenwhentheoxygenconcentrationofthesameexhaustgasismeasured(seeFigure8.1).Thisdifferencebetweenthemeasurementtypesislargestwhengascontainingmuchhydrogenisburned(sincemuchwatervaporisgenerated).Specialcareisrequiredwhentheoutput(basedonawetgas)ofthezirconiaoxygenanalyzeriscalculatedincombinationwithotheranalyticalvaluesmeasuredbasedonadrygas(forexample,COorNOxconcentrationmeasuredusinganinfraredgasanalyzer).Note: OurmodelZR402GZirconiaOxygenAnalyzerConverterincorporatesa“drygas-based”calculationfunction;itcanoutputdry

gas-basedvalues.

F0801.aiWet gas-based value Dry gas-based value

N271.2%

CO28.6%

Moisture content

O2 2.6%Ar 0.9%

100%

N2

CO2

Moisture content that has been

removed

O2

Ar

100%10.3%

85.5%

3.1%1.0%

Figure 8.1 Values based on a wet gas or dry gas

8.5 In Case Equipment is Turned On and Off Frequently

Toavoidtemperaturechangesaroundthesensor,itisrecommendedthat(ratherthanturningitonandoff)powerbecontinuouslysuppliedtotheOxygenAnalyzerifitisusedinanapplicationwhereitisusedperiodically.Itisalsorecommendedtoflowaspangas(instrumentair)beforehand.

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Revision HistoryManualTitle:ModelZR22G,ZR402G

DirectIn-siteSeparatetypeZirconiaOxygenAnalyzers(HardwareEdition)

ManualNumber:TI11M12A01-03E

December 2010/1st Edition Newlypublished

Documents

Model ZR22G, ZR402G Direct in-situ Separate Type Zirconia ... · • For the Zirconia cell, which is a key component of zirconia oxygen analyzers, a zirconia element and platinum