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POWER CATALOG Tab Document Name Part Number 1 TABLE OF CONTENTS.................................................................................................... N/A 2 COMBUSTION AIRFLOW APPLICATIONS Measuring Combustion Airflow & Pulverized Coal Flow..................................................ICA-11 Measuring Primary Airflow...............................................................................................ICA-01 Measuring Bulk Secondary Airflow..................................................................................ICA-02 Measuring Bulk Secondary Airflow..................................................................................ICA-03 Measuring Individual Burner Airflow ................................................................................ICA-06 Pf-FLO with Mill Inlet Diverter..........................................................................................ICA-09 Measuring Individual Burner Airflow ................................................................................ICA-10 3 COMBUSTION AIRFLOW MEASURING SYSTEMS VOLU-probe/SS Stainless Steel Pitot Airflow Traverse Probe .......................................125-068 Combustion Airflow (CA) Measurement Station .............................................................125-495 CAMS Combustion Airflow Management System ..........................................................125-009 VELTRON DPT-plus Microprocessor Based Transmitter ...............................................125-025 4 PULVERIZED COAL FLOW MEASURING SYSTEMS Pf-FLO IIITM Pulverized Coal Flow Measurement ...........................................................125-196 “Progress Energy” Sutton 3 NOx Reduction through Combustion Optimization ................ N/A Pf-FLOTM Reference Test at the Martin-Luther University Halle-Wittenberg...................... N/A 5 INDIVIDUAL BURNER AIRFLOW MEASURING SYSTEMS Individual Burner Airflow Measurement ..........................................................................125-510 Accurate Burner Airflow Measurement for Low NOx Burners – D.B. Riley ........................ N/A 6 CONTINUOUS EMISSIONS MONITORING SYSTEMS CEM Systems – Continuous Emissions Monitoring........................................................125-491

Proven solutions for a tough industry

1050 Hopper Avenue www.airmonitor.com [email protected] 707.544.2706 - P Santa Rosa, CA 95403 707.526.9970 - F

AIR MONITORP O W E R D I V I S I O N

ICA-11

MEASURING COMBUSTION AIRFLOW

& PULVERIZED COAL FLOW

While the importance placed on combustion optimization for the purposes of reducing emissions andimproving efficiency varies by power plant, there are common applications at every power plant that wouldgreatly benefit from improved airflow measurement or the addition of pulverized coal flow measurement. AirMonitor Power is both pioneer and leader in the development of systems to accurately and reliably measurecombustion air and coal flow, with thousands of installations at virtually every utility in the United States. Theaccompanying application bulletins outline the methods and benefits of measuring air and coal flow at thelocations indicated in the boiler overview below.

When applied by themselves or in combination, the addition of air and coal flow measurements will directlycontribute to:

• REDUCING CO, LOI & NOX

• REDUCING WATER WALL CORROSION

• IMPROVING MILL & BURNER PERFORMANCE

• ELIMINATING COAL LAYOUT, MILL PLUGGAGE, PIPE FIRES & SLAGGING

• LOWERING SCR OPERATING COSTS & ACHIEVING DESIRED BURNER STOICHIOMETRY

CEM

SAPA

Pf-FLO

IBAM

OFA



APPLICATION BULLETIN

P.O. Box 6358 Santa Rosa, CA 95406 707-544-2706 - P 707-526-9970 - F www.airmonitor.com

ICA-01

4/09, Rev.1

Ductwork providing primary air to apulverizer typically has limited straightruns, control dampers, and aconvergence point of hot andtempering air, all of which make theselection and placement of the airflowmeasurement device(s) critical to thesuccess of the installation. Thefollowing three examples show theuse of Fechheimer-Pitot CombustionAir (CA) stations and/or VOLU-probe/SS arrays, and their optimumlocations.

In applications with at least 1½diameters of straight duct run betweenthe hot air/tempering air mixing pointand the elbow upstream of thepulverizer control damper, a CA stationis used to measure total primary air.See Figure 1.

while insufficient primary air results inslagging, coal layout, pipe fires,“eyebrows”, and burner pluggage.

Usable measurement of primary aircannot be obtained from existing devicessuch as venturis, foils, jamb tubes, etc.,or instrumentation such as thermalanemometers due to limited availablestraight duct runs, low flow rates, broadturndown range and high concentrationsof airborne particulate (flyash). The needis airflow instrumentation capable ofovercoming these challenging operatingconditions, to optimize both mill operationand burner performance.

MEASURING PRIMARY AIRFLOW

The objectives in the power industrytoday are twofold; to lower emissions,and increase plant performance.Precise measurement of combustionairflow and fuel rates positivelycontributes to achieving thoseobjectives by providing the informationneeded to optimize stoichiometricratios and facilitate more complete,stable combustion.

The main functions of primary air areto dry the coal and then pneumaticallyconvey the pulverized coal from themill to the individual burners. Primaryair also determines coal particlevelocity at the burner exit, in partdefining the flame position relative tothe burner tip and impacting flamestability, both key factors in achievingoptimized burner performance.Excessive primary air contributes tohigh NO

x formation and tube erosion,

The Challenge The Solution

Figure 1

CA Station w/Temperature Probe and Transmitter

CAMS Purge and Transmitter

Opposed Blade Damper

T.P. and S.P. Signal Tubing

4-20mADC from Temperature Sensor

4-20mADC Flow Signal to DCS (lbs/hr)

100 psi Plant Air

A

E

F

G

H

I

K

ash. The purge cycle can beconfigured to operate on aprogrammable interval or initiated viaa dry contact from the DCS. Duringthe purge cycle the CAMM maintainsa locked signal output to the DCSwhile providing a dry contactnotification of purge cycle start andfinish.

These systems provide airflowmeasurement accurate to within ±3%of actual airflow over a 10:1 turndownrange. The signals remain stable withzero drift, and due to AUTO-purge theflow elements can operatecontinuously within the heavyparticulate environment. To datethousands of these systems havebeen installed within fossil fuel powerplants to help reduce NO

x and CO,

improve flame stability, avoid coal pipelayout, minimize LOI/UBC, increasecombustion efficiency, and reducewaterwall corrosion.

Coal mass flow and particle velocitydata from a Pf-FLO coal flowmeasurement system allow furtheroptimization of primary air by providingthe means of customizing a mill’s PAto Feeder curve to meet the uniqueoperating conditions of each powerplant; curves that are dependent uponvariable coal type, moisture content,coal pipe arrangement, and actualfuel distribution.

the CAMS enclosure the pressure signalsplus airflow temperature are convertedby the CAMM into a density compensatedlbs/hr mass flow output to the DCS.When two flow elements are supportedby a single CAMS, both the individualand summed mass flow outputs aremade available to the DCS.

The CAMM also manages the AUTO-purgeTM system used to keep the airflowstation or probe array sensing ports andsignal lines clear of accumulating fly

Where insufficient straight duct runexists downstream of the air mixingpoint, or separate measurement ofhot and tempering air is desired tocontrol mill outlet temperature, CAstations or VOLU-probe/SS arrayscan be installed in both air ductsupstream of the control dampers, oneduct diameter for the CA Station andtwo diameters for the VOLU-probe/SS array. See Figure 2.

On exhauster mills the tempering airis often not ducted but instead entersvia a “barometric opening” on the sideof the ductwork. For this applicationan integrated bell mouth CA stationwith extended casing is utilized tocreate the necessary minimum run ofstraight ductwork needed toaccurately measure the temperingairflow. A control damper can also beadded. See Figure 3.

The total and static pressure signalsfrom one or both CA Stations or VOLU-probe/SS arrays are routed to theCombustion Airflow ManagementSystem (CAMS) enclosure. Within

The Solution (con't)

Result

Figure 2

Figure 3

CA Station

CA Station w/Bellmouth

VOLU-probe/SS Array

Thermocouple Probe w/TemperatureTransmitter


Opposed Blade Damper




100 psi Plant Air

A

B

C

D

E

F

G

H

J

K



ICA-02

4/09, Rev.1

need for five to eight straight lengthsof duct runs at the point of installationto obtain true accuracy andrepeatability, 4) Cannot achieve alinear mass flow output over a broadoperating range with a single K-factor.

fuel ratio at varying load conditions.Although airfoils and venturis haveprovided adequate airflow measurementin the past, achieving current emissionreduction mandates and performanceobjectives require a more accurate andcost effective means of airflowmeasurement.

Venturis and airfoils have knownlimitations: 1) Significant non-recoverable pressure loss that wastespower and can limit generated output; 2)Decreased accuracy and noisy signalsat high turndown operating conditionsassociated with low NO

x retrofits; 3) The

MEASURING BULK SECONDARY AIRFLOW


Traditional coal fired power plantdesign utilized airfoils or venturis formeasurement of bulk primary andsecondary airflow for the purpose ofmaintaining the correct boiler air to

The Challenge

The Solution

A Florida utility was engineering a lowNO

x burner retrofit on their 300MW

gas/oil wall fired boiler. In order to gainneeded fan capacity and obtain a moreaccurate measurement of airflow overa higher range of turndown, Air MonitorPower’s Application EngineeringDepartment suggested the total airventuri be removed and replaced witha VOLU-probe/SS array. See Figure1.

Figure 1

System (CAMS) enclosure. Within theCAMS enclosure the pressure signalsplus airflow temperature are convertedby the CAMM into a density compensatedlbs/hr mass flow output to the DCS. Thetwo mass flow inputs, one from eachCAMM, were summed in the DCS toarrive at a total bulk airflow.See Figure 2.

The CAMM also manages the AUTO-purgeTM system used to keep the VOLU-probe/SS sensing ports and signal linesclear of accumulating fly ash. The purgecycle can be configured to operate on aprogrammable interval or initiated via adry contact from the DCS. During thepurge cycle the CAMM maintains alocked signal output to the DCS whileproviding a dry contact notification ofpurge cycle start and finish.

The measuring location was a 40’long section of duct downstream oftwin forced draft (FD) fans and arotary air pre-heater. The two fansjoined into a common 5’ x 75’ ductupstream of the pre-heater, and itwas believed that the flow rates oneither side of the duct would varydepending on the load changes oneither fan.

Two side-by-side measurementarrays, each having sevenFechheimer-Pitot VOLU-probe/SSmeasuring 60" in length, wereinstalled. For each array the VOLU-probe/SS total and static pressuresignal connections were manifoldedtogether and routed to their ownCombustion Airflow Management

ResultThe Solution

The removal of the venturi providedthe needed additional fan capacity,while saving an estimated $10,000 inreduced power consumed by eachFD fan. The installed VOLU-probe/SS arrays achieved the desired ±3%measurement accuracy over the full4:1 range of turndown. Due to theCAMS sensitivity to small changes inairflow, a cyclic drop in airflow wasdetected and traced back to one ofthe pre-heater’s twelve sections beingplugged.

Subsequent to the initial installation,Air Monitor Power assisted thecustomer in reconfiguring themanifolding of the two VOLU-probe/SS arrays as in Figure 3. The revisedarrangement resulted in two fullyredundant systems, each measuringthe total bulk airflow without anysumming in the DCS. When onesystem was performing a purge cycle,the other system continued to providedynamic flow measurement.

VOLU-probe/SS Array

Thermocouple Probe w/Temperature Transmitter



100 psi Plant Air



A

B

C

D

E

F

G

Figure 2 Figure 3



ICA-03

4/09, Rev.1

Venturis and airfoils have knownlimitations: 1) Significant non-recoverable pressure loss that wastespower and can limit generated output;2) Decreased accuracy and noisysignals at high turndown operatingconditions associated with low NO

x

retrofits; 3) The need for five to eightstraight lengths of duct run at the pointof installation to obtain true accuracyand repeatability, 4) Cannot achieve alinear mass flow output over a broadoperating range with a single K-factor.

Traditional coal fired power plant designutil ized airfoils or venturis formeasurement of bulk primary andsecondary airflows for the purpose ofmaintaining the correct boiler air to fuelratio at varying load conditions. Althoughairfoils and venturis have providedadequate airflow measurement in thepast, achieving current emissionreduction mandates and performanceobjectives require a more accurate andcost effective means of airflowmeasurement.

MEASURING BULK SECONDARY AIRFLOW


The Challenge

notification of purge cycle start and finish.FD fan operating costs were reducednearly $50,000 per year, resulting in a21-month payback for the project. As aresult of the installed VOLU-probe/SSarrays measurement accuracy wasgreatly improved, to within 3% of actualairflow over the 4:1 range of turndown.

Air Monitor Power’s ApplicationEngineering Department was calledupon by a Georgia utility to designand provide airflow measuringsystems to replace three airfoils andone air dam within their 500MW, coalfueled, T-fired boiler. The projectobjective was to gain needed FDcapacity, with the cost justificationexpected to come from a reduction inenergy required to operate the FDfans.

Airfoils in three locations and an airdam were removed – one airfoil ineach of the 12’ x 15’ bulk secondaryair ducts, one airfoil in the 6’ x 6’ hotprimary air duct serving the mills, andthe air dam in the 5’x 5’ tempering airduct. Fan curve data indicated thetotal non-recoverable pressure losscaused by the airfoils and air damwas slightly more than 3" w.c., wastingnearly 300 HP per fan.

An array of Fechheimer-Pitot VOLU-probe/SS were installed in each of thefour measurement locations: Tenprobes 12’ in length in each of the twosecondary air duct, five probes 6' inlength within the hot PA duct, andfour probes 5' in length in thetempering air duct. For each arraythe VOLU-probe/SS total and staticpressure signal connections weremanifolded together and routed totheir own Combustion AirflowManagement System (CAMS)enclosure. Within the CAMSenclosure the pressure signals plusairflow temperature are converted bythe CAMM into a densitycompensated lbs/hr mass flow outputto the DCS.

The CAMM also manages the AUTO-purgeTM system used to keep theVOLU-probe/SS sensing ports andsignal lines clear of accumulating flyash. The purge cycle can beconfigured to operate on aprogrammable interval or initiated viaa dry contact from the DCS. Duringthe purge cycle the CAMM maintainsa locked signal output to the DCSwhile providing a dry contact

ResultThe Solution



ICA-06

4/09, Rev.1

angles blades in each barrel, acombination of fixed and/or adjustableinlet sleeve/disk dampers, and in mostinstallations the burners were equippedwith actuators to facilitate DCS controlledmodulation of burner SA airflowcorresponding to varying fuel loads.Unfortunately some low NOx burnerscome equipped with a non-calibratedairflow sensing device and most otherslack any means to determine how muchSA is entering the burner, resulting in theneed for extensive burner tuning targetedat meeting the manufacturer’s NOx andCO emissions guarantees but notrepeatable or maintainable long termover varying load conditions.

Just as there are variances in fueldistribution to each burner, multiple

MEASURING INDIVIDUAL BURNER AIRFLOW


Traditional coal fired power plantdesigns lacked any means to measureand control airflow into individualburners. New burner designsprompted by Clean Air Act attainmentlevels for NOx reduction are typicallycomprised of inner and outer airflowbarrels to introduce secondary air (SA)to the flame ball, adjustable swirl

The Challenge

burners served by a common orpartitioned wind box can havesubstantial burner-to-burner im-balances in SA Accurate andrepeatable measurement of individualburner SA requires airflow probes thatare economically feasible to retrofitinto existing burners and yet able toaccommodate a variety of designchallenges – the absence of anyundisturbed cross section of airflowpassage; an installation locationtypically downstream of a modulatinginlet sleeve or disk damper; a broadrange of boiler operating conditions;the presence of fly ash particulate; andthe broad range of airflow pitch andyaw vectors produced by the adjustableswirl angle blades.

Customized IBAMs characterized inthe Air Monitor Power wind tunnel andused in conjunction with a CAMS resultin individual burner SA measurementaccurate to within ±5% of actual airflowover the full range of boiler operation.

Statically balanced burner-to-burnerairflow is a critical first step in optimizingboiler performance while simul-taneously reducing undesirableemissions. In several installations, justbalancing the airflow was sufficient toachieve lower NOx emissions levels.

Further reductions in NOx levels areobtained when continuous burner SAmeasurement is combined with DCScontrolled modulation of airflow controlto dynamically maintain burner-to-burner airflow balance or a burnerbias strategy corresponding to thevarying fuel loads.

Incorporating Pf-FLO coal flowmeasurement for EACH burnerpermits adjusting SA to reflect theactual fuel being delivered to eachburner, thereby achieving the desiredfuel / air ratio, safely lowering overallNOx while simultaneously reducingareas of high CO that otherwiseproduce undesirable slagging andwater wall corrosion.

Over-fire Airflow (OFA) measurementis another common NOx reductiontechnique that alone, or in conjunctionwith SA measurement and control,requires the accurate measurementcapabilities of the IBAM to ensure theproper amount of OFA is used toobtain the best possible NOx solutionvia staged combustion, whilesimultaneously minimizing CO andLOI.

The IBAM signals are routed out of thewind box to the Combustion AirflowManagement System (CAMS)enclosure. Within the CAMS enclosurethe pressure signals plus airflowtemperature are converted by the CAMMusing the polynomial equation, into adensity compensated lbs/hr mass flowoutput to the DCS.

The CAMM also manages the AUTO-purgeTM system used to keep the IBAMsensing ports and signal lines clear ofaccumulating fly ash. The purge cyclecan be configured to operate on aprogrammable interval or initiated via adry contact from the DCS. During thepurge cycle the CAMM maintains alocked signal output to the DCS whileproviding a dry contact notification ofpurge cycle start and finish.

Air Monitor Power’s Individual BurnerAirflow Measurement (IBAM) probes,a modified version of the VOLU-probe/SS, are designed burner specific toaccurately measure burner SA.Based upon the Fechheimer-Pitotmeasurement technology, each IBAMdesign draws from a broad array ofconstruction options: Quantity andlocation of individual TP and SPsensing holes; CW and/or CCWrotation of the individual TP and SPsensing probes; rotation of the entireIBAM assembly; and the use of ultrahigh temperature alloys and TungstenCarbide coatings. The configurationof inner and outer airflow barrels,along with the locations of the burnerregisters and obstructions such as anigniter, typically define the possibleIBAM mounting locations. Wind boxconfiguration and burner symmetryguide the quantity of IBAMs neededto obtain desired accuracy andrepeatability.

Each IBAM probe is extensively testedand characterized in Air MonitorPower’s large scale test duct, installedeither in a full size burner mock-up orthe actual burner. Testing isconducted over a broad matrix ofcustomer specific sleeve damper orinlet disk positions, swirl anglesettings, and boiler operatingconditions. The result is a multi-orderpolynomial equation, with one or twovariables, to accurately correlate thetotal and static pressure signals fromthe IBAMs into mass flow.

ResultThe Solution



ICA-09

4/09, Rev.0

non-repeatable tuning of burner settingssolely targeted at meeting themanufacturer’s NO

x and CO emissions

guarantees at a single load condition.Such burner tuning did nothing to addresssignificant variances in fuel distributionto each burner, while multiple burnersserved by a common or partitioned windbox continued to have substantial burner-to-burner imbalances in secondaryairflow (SA). The result was littlesustainable improvement in overall boileroperation over a range of load conditions.

A Southeast Utility wanted to implementa comprehensive and sustainablecombustion optimization managementstrategy for one of their wall-fired boilers,recently upgraded with low NO

x burners

that were not equipped with any means

Pf-FLO with MILL INLET DIVERTER


Traditional designs of coal fired powerplants lack any means to measureand control airflow into individualburners. This practice changed whenNO

x attainment levels mandated by

the Clean Air Act prompted installationof low NO

x burners which,

unfortunately, were frequentlyaccompanied by extensive and often

The Challenge

to measure burner SA. The scope ofthe project involved upgrading millprimary air measurement, installingindividual burner SA measurement,and adding instrumentation to measurethe amount of pulverized coal beingdelivered to each burner.

The boiler was equipped with Atritadouble ended mills, each fed by asingle duct providing both fuel andprimary air to the mill. See Figure 1below. Each mill end fed an exhauster,which in turn delivered fuel to a pair ofburners after passing through a primaryriffle box. Based upon their manyyears of experience operating the Atritamills the Util ity’s combustionengineering group was convinced theshared coal / PA duct configurationproduced variable end-to-end coalimbalance, which in turn resulted intwo of each Mill’s four pipes gettingmore pulverized coal than the othertwo pipes. See Figure 2.

Figure 1

Air Monitor Power assisted the Utility’scontractor in the development of newcontrol logic using the coal mass flowmeasurements from each of the fourpipes served by a single mill; bysumming the two coal flowmeasurements corresponding to eachmill end a control output was generatedto reposition the diverter damper,automatically maintaining end-to-endmill balance within ±5%. Data fromthe Pf-FLO system was also used toguide the process of statically adjustingeach primary riffle box to balance thefuel being delivered to both burners.The combined effect of manual riffleadjustment and implementation ofautomatic diverter damper control wassuccessful in achieving the primaryobjective of ±10% coal deliverybalance to all burners over the normalrange of boiler operation.

In conjunction with the coal diverter a Pf-FLO Coal Flow Measurement Systemwas installed on all 20 pipes, initially togather baseline coal distribution dataover the Unit’s full range of loadconditions. By summing the mass flowof pipes 1 & 2 served by the mill’s left endand comparing it to the summed massflow of pipes 3 & 4 served by the mill’sright end, the baseline data collected inPf-VU confirmed the existence of 20%end-to-end imbalance at different loadconditions, and as much as 35% fuelvariance between the lightest andheaviest loaded pipes. By means ofmanually biasing the diverter bladeposition the ability to achieve mill end-to-end balance was demonstrated.

To address the end-to-end fuelimbalance Air Monitor Power’sApplication Engineering departmentengineered a coal diverter withactuator that was installed into the topsection of the existing coal / PA duct.Diverter components directly exposedto coal were constructed of wearresistant alloys, with an overall designthat permitted ease of periodicinspection for long term removal andreplacement. The diverter wasengineered to permit as much as±25% end-to end bias via a controlsignal from the DCS. A divider platewas also installed to maintain the coaldistribution from the diverter into themill entrance. See Figure 1.

ResultThe Solution

Figure 2



ICA-10

4/09, Rev.0

adjustment of the secondary airflow is tobe applied to each burner compartment.

Air Monitor Power’s ApplicationEngineering department was called uponby a Southeast utility to design a systemto measure airflow entering the individualfuel and aux air compartments of theirtangentially fired 350MW plant, wherenew low NO

x burners were being installed

as part of a total boiler upgrade.

The design solution was based upon thefact that airflow passing through a fixedresistance element (louver, perforatedplate, orifice plate, etc.) produces ameasurable, repeatable pressure drop,such that the airflow can bemathematically expressed in the form ofa power curve or polynomial equationusing pressure drop as the variable. In

MEASURING INDIVIDUAL BURNER AIRFLOW


Traditional designs of tangentiallyfired, coal power plants lack anymeans to measure secondary airflowentering each fuel and aux aircompartment. Efforts to meet NOxattainment levels mandated by theClean Air Act were frequently achievedby means of extensive and often non-repeatable tuning of burner settingssolely targeted at meeting the NOxand CO emissions guarantees at asingle load condition. Just as thereare variances in fuel distribution toeach burner, multiple burners servedby a common wind box ended up withsubstantial burner-to-burner imbal-ances in secondary airflow (SA).

On tangentially fired boilers themodulating control damper at theentrance to each secondary air inlethas little if any straight duct run, notproviding a location where even just arepeatable signal representative ofactual airflow can be obtained. Sincethe secondary air inlets are not easilyaccessed for maintenance or repair,any airflow measuring instrumentationmust be durable and repeatable,providing stable, accurate inputsignals to the DCS if a combustionoptimization strategy using continuous

The Challenge

this tangentially fired application thedampers are modulated to controlairflow, thereby making them variableresistance elements whoserelationship to airflow becomes amathematical function of two variables– the measured pressure drop acrossthe damper and the damper position.

Each corner consisted of four burnerelevations with three blade controldampers, five aux air compartmentswith two blade dampers, plus a top airand a bottom air compartment eachwith a single damper blade. A full scalemock-up of the wind box corner wasconstructed, complete with physicalreplications of the three differentdamper configurations, equipped with

The Solution

An engineered solution consisting ofcustomized SAP sensors, detaileddamper characterizations and CAMSresulted in individual compartment SAmeasurement accurate to within ±5%of actual airflow over the full range ofboiler operation.

The ability to accurately balance and/or bias individual corner airflow was acritical first step in optimizing boilerperformance while simultaneouslyreducing undesirable emissions.Further reductions in NO

x levels were

obtained when the continuous cornerSA measurements were combinedwith nozzle tilt adjustments and DCScontrolled modulation of the controldampers to dynamically maintain aburner and aux air strategy at varyingfuel loads.

In addition to its essential contributionto optimization of PA / Feeder curves,incorporating Pf-FLO coal flowmeasurement for EACH burnerallowed automatic adjustment of SAto reflect the actual fuel being deliveredto each burner, thereby achieving thedesired fuel / air ratio for each burnerwhile safely lowering overall NO

x and

reducing areas of high CO thatotherwise produce undesirableslagging and water wall corrosion.

ruggedized version of Air Monitor’s SAP(Static Air Probe) was engineering tomeet the application requirements.

The static pressure signals from theupstream and downstream SAPs wererouted out of the wind box to theCombustion Airflow ManagementSystem (CAMS) enclosure. Within theCAMS enclosure the pressure signals,airflow temperature, and damper positioninput are converted by a CAMM/TFAusing the multi-order dampercharacterization equations, into a fullydensity compensated lbs/hr mass flowoutput to the DCS.

The CAMM/TFA also manages theAUTO-purgeTM system used to keep theSAP sensing ports and signal lines clearof accumulating fly ash. The purge cyclecan be configured to operate on aprogrammable interval or initiated via adry contact from the DCS. During thepurge cycle the CAMM/TFA maintains alocked signal output to the DCS whileproviding a dry contact notification ofpurge cycle start and finish.

the new actuators that were part ofthe boiler upgrade, and attached toAir Monitor Power’s large scale testduct. Based upon customer providedcurrent and future operatingparameters, a 286 point test matrixconsisting of three variables (windboxstatic pressure, damper position,damper size) was developed forcharacterizing each damperindividually, followed by verificationtesting of multiple dampers beingmodulated simultaneously. The resultwas a developed series of multi-orderpolynomial equations correlating thepressure drop signal and damperposition into air mass flow.

A key component of the project wasdesigning the static pressure sensorsrequired to measure the pressure dropacross the control dampers. Thesensors had to operate in thepresence of fly ash particulate, beeconomically feasible to retrofit intothe existing compartments, and notbe adversely impacted by changingairflow patterns downstream of themodulating dampers. A custom

ResultThe Solution (con't)



ICA-12

4/09, Rev.1

by ASME, ASHRAE, and in fluidmechanics textbooks.

Air Monitor Power’s line of applicationproven Combustion AirflowManagement Modules (CAMM) withultra-low spans (as low as 0.05" w.c.Full Span) and high accuracy (0.1% ofFull Span) allows the engineering ofventuris with an optimized high .8 betafactor – one that optimizes the flowprofiling benefits as air is compressedpassing through the throat of theventuri, against the unrecoveredpressure drop of the venturi itself. Theresultant Venturi/HBTM (High Beta)maximizes the amount of primary airavailable to the mill while providingaccurate airflow measurement over awide range of operation.

Venturis have long been used in powergeneration to measure airflow becauseof their ability to create a differentialpressure signal that could be fieldcharacterized to represent lbs/hr of air.Historically venturis with a .5 beta factor(the ratio of venturi minimum crosssection to the full size upstream ductcross section) were engineered toproduce the 20-30 inches of differentialpressure required by the differentialpressure transmitters of that era, but didso at the expense of a high unrecoveredpressure drop, waste of energy andimposed limit on available air for com-bustion. The measurement performanceof traditional venturis was furthercompromised by field calibrationmethods relying on the use of the S-typePitot in duct locations far short of theminimum requirements recommended

MEASURING PRIMARY AIRFLOW


The main functions of primary air areto dry the coal and then pneumaticallyconvey the pulverized coal from themill to the individual burners. Primaryair also determines coal particlevelocity at the burner exit, in partdefining the flame position relative tothe burner tip and impacting flamestability, both key factors in achievingoptimized burner performance.Excessive primary air contributes tohigh NO

x formation and tube erosion,

while insufficient primary air results inslagging, coal layout, pipe fires,“eyebrows”, and burner pluggage.

Short duct sections are commonplacein coal fired power plants and AirMonitor Power, with its Fechheimer-Pitot Combustion Air (CA) stationsand/or VOLU-probe/SS arrays, hasdemon-strated the ability to accuratelymeasure combustion airflow withoutthe need for field calibration. Butprimary airflow typically combines hotand tempering air supplies with controldampers and limited straight ductsections, resulting in ductworkconfigurations that produce highlydistorted velocity profiles, often withairflow angularity beyond the ±30degrees of pitch and/or yawmeasurement accuracy limitations ofa CA station or VOLU-probe/SS array.

The Challenge The Solution

VENTURI/HBTM

Shown with optionalVOLU-probe/SS

Customized Venturi/HBs characterizedin Air Monitor Power’s wind tunnel andused with a CAMS will providemeasurement accuracy to within ±3% ofactual primary airflow over the full rangeof mill operation. The signals remainstable with zero drift, and due to AUTO-purge the flow elements can operatecontinuously within the heavy particulateenvironment. These systems help reduceNO

x and CO, improve flame stability,

avoid coal pipe layout, minimize LOI/UBC, increase combustion efficiency,and reduce waterwall corrosion.

Coal mass flow and particle velocity datafrom a Pf-FLO coal flow measurementsystem allow further optimization ofprimary air by providing the means ofcustomizing a mill’s PA to Feeder curveto meet the unique operating conditionsof each power plant; curves that aredependent upon variable coal type,moisture content, coal pipe arrangement,and actual fuel distribution.

Each Venturi/HB is extensively testedand calibrated in Air Monitor Power’slarge scale test duct, with the testarrangement constructed to matchthe actual upstream and downstreamductwork configuration, damper(s),etc. Testing is conducted over thecustomer’s full range of flow ratesand damper positions. The result istypically a multi-order polynomial thatis programmed into the CAMM orDCS to accurately determine densitycompensated lbs/hr massflow usingmeasured venturi differentialpressure, airflow temperature, andstatic pressure.

As optional construction for fullymaintenance free operation, theCAMM would be part of a CombustionAirflow Measurement System(CAMS) that includes the AUTO-purgeTM system that uses compressedair to keep the venturi sensing portsand signal lines clear of accumulatingfly ash. The purge cycle can beconfigured to operate on aprogrammable interval or initiated viaa dry contact from the DCS. Duringthe purge cycle, the CAMM maintainsa locked signal output to the DCSwhile providing a dry contactnotification of purge cycle start andcompletion.

The Venturi/HB comes standardequipped with traverse ports locatedin the throat area. As an optionalfeature, an array of test duct calibratedVOLU-probe/SS can be purchasedfor a group of same sized Venturi/HB’s. The VOLU-probe/SS aredesigned to mount in the venturi throatvia the traverse ports, permittingsimple periodic verification of eachventuri’s measurement accuracywithout the need to perform timeconsuming field traversing.

The Solution (con't) Result

Construction Options

• Rectangular & circular configurations

• AUTO-purge for automatic sensingport and signal line high pressurepurging

• Bolt-on or permanently installedtraverse ports

• Temperature probe port

• Mating flanges for existing duckwork

VOLU-probe/SSStainless Steel Pitot Airf low Traverse Probes

Proven solutions for a tough industry AIR MONITORP O W E R D I V I S I O N

The VOLU-probe/SS Stainless Steel Pitot Airflow Traverse Probeis ideally suited for new installations or retrofit applicationsrequiring accurate airflow measurement in locations having limitedstraight duct runs. Multiple sets of total and static pressure sensingports along the entire length of the VOLU-probe/SS traverse theairstream in a single line across the duct, and average the sensedpressures in separate manifolds. An array of VOLU-probe/SS

probes are used to properly sense the typically stratified flow toprovide an equal area traverse of an entire duct cross-section. TheVOLU-probe/SS is suited for clean or harsh and particulate ladenapplications, operating at temperatures ranging from –20 to 900ºF.As a primary flow sensing means, the VOLU-probe/SS can be usedin industrial process applications ranging from power generation(combustion airflow), fiber quenching, process drying, emissionmonitoring, etc.

Product Description

VOLU-probe/SS

When installed per Air Monitor's Minimum InstallationRequirements (see back page), the minimum quantity and placementof VOLU-probe/SS airflow traverse probes shown below willproduce assured measuring accuracies of ±2-3% of actual airflow.

Accuracy

All recognized flow measurement standards (ASHRAEFundamentals, AMCA Publication 203, Industrial VentilationManual, 40CFR60, etc.) agree that accurate airflow measurementis highly dependent upon the quantity and pattern of sensing pointsin the airstream, and the relative position of the sensing points toupstream/downstream flow disturbances.

static sensor experiences a lower pressure (Ps – part of Pt) of thesame magnitude, thereby canceling out the undesired effect ofpartial total pressure (Pt). It is this unique design of offset staticpressure and chamfered total pressure sensors (see Figure 1) thatmake the VOLU-probe/SS insensitive to approaching multi-directional, rotating airflow with yaw and pitch up to 30º fromstraight flow, thereby assuring the accurate measurement of thesensed airflow rate without the presence of an airflow straightenerupstream. This unique design of the VOLU-probe/SS is coveredby U.S. Patent No. 4,559,835.

How It Works

The VOLU-probe/SS operates on the Fechheimer Pitot derivativeof the multi-point, self-averaging Pitot principle to measure thetotal and static pressure components of airflow. Total pressuresensing ports, with chamfered entrances to eliminate air directioneffects, are located on the leading surface of the VOLU-probe/SSto sense the impact pressure (Pt) of the approaching airstream (seeFigure 2). Fechheimer pair of static pressure sensing ports,positioned at designated angles offset from the flow normal vector,minimize the error inducing effect of directionalized airflow. Asthe flow direction veers from the normal, one static sensor isexposed to a higher pressure (Ps + part of Pt), whereas the other

Figure 1 Figure 2

The VOLU-probe/1SS is designed for mounting in ducts or stacksby drilling two holes in opposing walls, without the need to enterthose structures.

The VOLU-probe/1SS is furnished with a threaded end support,gasketed washer and nut, and a mounting plate with signal take-offFPT connections, all fabricated of type 316 stainless steel.

VOLU-probe/1SS – Externally Mounted

VOLU-probe/1SS & 2SS

The VOLU-probe/2SS is designed for larger ducts or stacks wherethe size permits entry for installation, or where duct externalaccessibility or clearance is insufficient to permit probe mountingfrom outside the duct.

The VOLU-probe/2SS is furnished with interior mounting and endsupport plates, and midpoint signal take-off FPT connections, allfabricated of type 316 stainless steel.

VOLU-probe/2SS – Internally Mounted

VOLU-probe/SS – Construction Options

VOLU-probe/SS Options

150 lb. Mounting Flange Probe End Supports

Temperature Probe Companion Mounting Plates

Construction Features

Stainless Steel Airf low Traverse Probes

Features

Provides for Equal Area Traverse. Each VOLU-probe/SScontains multiple total and static pressure sensors specifically andprecisely located along the length of the probe to provide an equalarea traverse of ducted airflow. For rectangular duct configurations,the sensors are spaced at equal distances along the probe. Forcircular duct configurations, the sensors are located at the centersof the equivalent concentric area along the probe.

True Velocity Pressure Measurement. The total and staticpressure components of airflow measured by the VOLU-probe/SScan be directly converted in velocity pressure (and velocity) withoutthe use of correction factors, thereby facilitating flow verificationwith a Pitot tube or other hand held instrumentation.

No Sensor Protrusions. The VOLU-probe/SS total and staticpressure sensors are all contained within the confines of the externalsurface of the probe. There are no protruding sensors to be bent,broken, or otherwise damaged during installation or possiblesubsequent removal for inspection or cleaning.

Rugged Construction Assures Long Service Life. The standardVOLU-probe/SS is fabricated from Type 316 stainless steel usingall welded construction. See Page 4 for construction options, andcontact Factory for alternate materials of construction such asHastelloy, Inconel, Kynar, PVC, etc.

No Air Straighteners Required. The VOLU-probe/SS uniquedual offset static pressure sensor and patented chamfered totalpressure sensor design permit the accurate measurement of theairflow rate in highly turbulent flow locations (with directionalyaw and pitch varying up to 30º from the duct's longitudinal axis)without the need for upstream air straightening means.

Offered in Two Models. The VOLU-probe/SS is offered in twobasic configurations to facilitate installation in new or existingducts or stacks; the Model 1 for external mounting, and the Model2 for internal mounting.

Negligible Resistance to Airflow. The VOLU-probe/SScylindrical configuration and smooth surface free of external sensorprotrusions permit the airstream to flow unrestricted around andbetween the installed traverse probes, creating a very minimal, ifnot negligible resistance to airflow (Ex: 0.046 IN w.c. at 2000 fpmair velocity).

Performs Equal-Weighted Averaging of Flow Signals. Throughthe use of separate averaging manifolds, the VOLU-probe/SSinstantaneously averages, on an equal-weighted basis, the multiplepressures sensed along the length of the probe, producing separate"averaged" total pressure and static pressures at the probe's externalsignal connections.

FPT Signal Connections

Offset Fechheimer Static Pressure Sensors

Integral 10 Gauge Mounting Plate

Chamfered Total Pressure Sensors

Note: VOLU-probe/SS locations shown are not ideal. The locations indicate the minimum clearance required from air turbulence producingsources. Wherever possible, the VOLU-probe/SS should be installed where greater runs of straight duct (or clearances) than shown below exist.

Minimum Installation Requirements

125-068 (1/99)Website (10/13)

VOLU-probe/SS

Suggested Specification

Provide where indicated an array of airflow traverse probes capableof continuously monitoring the stack or duct capacities (air volumes)it serves.

Each airflow traverse probe shall contain multiple total and staticpressure sensors and internally connected to their respective averagingmanifolds. The flow sensors shall not protrude beyond the surfaceof each probe, and shall be the offset (Fechheimer) type for staticpressure and the chamfered impact type for total pressuremeasurement. The airflow sensing probe's measurement accuracyshall not be affected by directional flow having pitch and/or yawangles up to 30º.

Each airflow traverse probe shall be fabricated of type 316 stainlesssteel, all welded construction, and shall be furnished with the flat orcurved plate mounting means. In addition, access ports and accessory

hardware shall be provided to facilitate external installation of theprobe and end support (if required), yet permitting easy proberemoval for inspection, etc.

The airflow traverse probe shall not induce a pressure drop in excessof 0.046 IN w.c. at 2000 FPM, nor measurably contribute to soundlevels within the duct. Total and static pressure sensors shall belocated at the centers of equal areas (for rectangular duct) or at equalconcentric area centers (for circular ducts) along the probe length.The airflow traverse probe shall be capable of producing steady,non-pulsating signals of total and static pressure without need forflow corrections or factors, with an accuracy of 2-3% of actual flow,over a velocity range of 400 to 4000 FPM.

The airflow traverse probe(s) shall be the VOLU-probe [1SS, 2SS]as manufactured by Air Monitor Corporation, Santa Rosa, California.

Rectangular Duct: x = Circular Duct: x = Duct Diameter

2 H x W

H + W

P.O. Box 6358 • Santa Rosa, CA 95406 • TEL 800-AIRFLOW • Fax 707-526-9970 • www.airmonitor.com AIR MONITORP O W E R D I V I S I O N

CA StationCombustion Airflow Measurement Station



CA Station

How It Works

The CA Station is also ideally suited to measure SA enteringeach burner level of a partitioned windbox, SA being takenout of a windbox to supply multiple OFA ports, at the ductedinlet of FD fans, and bulk SA entering each windbox of acorner fired unit.

The Need for Combustion Airflow Measurement

The objectives in the power industry today are twofold; tolower emissions, and increase plant performance. Precisemeasurement of combustion airflow and fuel rates positivelycontributes to achieving those objectives, by providing theinformation needed to optimize stoichiometric ratios andfacil i tate more complete, stable combustion. Usablemeasurements cannot be obtained from existing devices suchas venturis, foils, jamb tubes, etc., or instrumentation suchas thermal anemometers due to limited available straight ductruns, low flow rates, proximity to modulating control dampers,broad turndown range, and high concentrations of airborneparticulate (flyash).

Air Monitor Power’s ruggedly constructed Combustion Air(CA) Station, with both integral airflow processing cell andFechheimer-Pitot measurement technology, is engineered tomeet the challenging operating conditions of the typical powerplant while providing mass flow measurement of PA, SA, andOFA within an accuracy of ±2-3% of actual airflow.

While the main functions of primary air are to first dry andthen pneumatically convey the pulverized coal from the millto the individual burners, it also determines coal particlevelocity at the burner exit, influencing the flame positionrelative to the burner tip and impacting flame stability, bothkey factors in achieving optimized burner performance.Accurate PA measurement obtained with a CA Station cancontribute to reducing NOx

and CO, improving flame stability,avoidance of coal pipe layout, minimizing LOI/UBC, reducingwaterwall corrosion, and increasing combustion efficiency.

Log-Tchebycheff Sensor Location. A high concentrationof total and static pressure sensors positioned according tothe log-Tchebycheff rule sense the multiple and varying flowcomponents that constitute the airstream's velocity profile.The log-Tchebycheff's perimeter weighted sensor pattern isutilized to minimize the positive error (measurements greaterthan actual) caused by the failure to account for slowervelocities at the duct wall when using traditional equal areasensor locations. Spacing of total pressure sensors is perthe table below. Since the static pressure across the stationis relatively uniform, a lesser number of static pressuresensors are utilized to minimize unrecovered pressure drop.

Fechheimer Pitot Flow Measurement. The CA Stationoperates on the Fechheimer-Pitot derivative of the multi-point,self-averaging Pitot principle to measure the total and staticpressure components of airflow. Total pressure sensing portswith patented (U.S. Patent No. 4,559,835) chamferedentrances, and Fechheimer pairs of offset static pressuresensing ports combine to minimize the effect of directionalairflow. When located downstream of honeycomb airflowprocessing cell, the Fechheimer Pitot method is extremelyeffective at accurately measuring airflow in limited straightduct runs.

Airflow Processing. To assure extremely high levels ofmeasuring accuracy (3% of actual flow) under extremeconditions caused by turbulent, rotating, and multi-directionalairflows normally present near fan inlets, discharge ducts,and directly downstream from duct elbows, transitions, etc.,the CA Station uses open, parallel cell, honeycomb panels to"process" the air into straightened flow just prior to the totalpressure measurement plane. These honeycomb panelssharply reduce the need for long, straight runs of duct beforeand after the station to obtain accurate flow measurement.

Negligible Airflow Resistance. The CA Station airflowmeasuring station is designed to function while producing aminimum of resistance to airf low, due to the uniquehoneycomb air straightener-equalizer section having a freearea of 96.6%. The unique, non-restrictive characteristic ofthe CA Station is seen in the Resistance vs. Airflow Velocitygraph below. The values indicated are total resistance anddo not include any allowances for static regain (a potential20% reduction to the values).

Denotes CA Station location

Duct / StationConfiguration

Rectangular

Circular

Quantity of Sensing Points

25 or more points, maximum 6" or 8" apart,depending on duct size.

12 to 30 points, along 2 or 3 diameters.


Combustion Airflow Measurement Station

Specifications


Welded 3/16"Carbon Steel Casing

90º Connection Flanges

12" Depth

24 ga. Carbon SteelAirflow Straightener

Offset Fechheimer StaticPressure Sensing Probe

Total Pressure Sensing Manifold

Configurations.Rectangular, Circular, and Custom

Accuracy.2-3% of actual flow

Operating Temperatures.Continuous operation to 800ºF

Connection Fittings.1/2" FPT, Type 316 stainless steel

Static and Total Pressure Sensing Manifolds.Type 316 stainless steel, welded construction

Airflow Straightener.1" hexagonal, parallel cell straightener, 3" deep,24 ga. (.024") thick carbon steel

Casing and Flanges.3/16" carbon steel, continuous welded seamsCasing depth is 12"

Special Construction Options.Sensing Manifold CleanoutsInlet Bell MouthMulti-point Temperature MeasurementAlternate Materials of ConstructionIntegral Control Damper

Optional Manifold Cleanouts

125-495 (04-09)

P.O. Box 6358 • Santa Rosa, CA 95406 • P: 800-AIRFLOW • F: 707-526-9970www.airmonitor.com • [email protected]

Air Monitor Power's Product Families of Air & Coal Flow Measurement Systems

IBAMTM – Individual Burner Airflow MeasurementThe IBAMTM – Individual Burner Airflow Measurement probe is ideally suited for new orretrofit applications where a reduction in plant emissions and improvement in efficiencycan be obtained through accurate measurement of burner secondary airflow. The IBAMTM

probe has been designed to accurately measure in the particulate laden, high operatingtemperature conditions found in burner air passages.

CEMSTM – Continuous Emissions Monitoring SystemAir Monitor Power's CEMSTM – Continuous Emissions Monitoring Systems assist incomplying with the Clean Air Act’s stringent emission measurement standards and therequirements of 40 CFR 75. Air Monitor has assembled a cost effective integrated systemconsisting of in-stack flow measurement equipment and companion instrumentation toprovide continuous, accurate, and reliable volumetric airflow monitoring of stacks and ductsof any size and configuration.

CAMSTM – Combustion Airflow Management Systems.

The CAMSTM – Combustion Airflow Management System has been designed to reliablyand accurately measure airflow in combustion airflow applications. The CAMSTM containsthe microprocessor based instrumentation to measure the airflow and manage the AUTO-purge. The AUTO-purge is a high pressure air blowback system that protects the ductmounted flow measurement device from any degradation in performance due to thepresence of airborne particulate (flyash).

Engineering & Testing Services. Air Monitor Power offers complete engineering and testing to analyze air and coaldelivery systems. Air Monitor Power’s field testing services use 3D airflow traversing and Pf-FLO coal flow measurementsystems for the highest possible accuracy. To ensure cost effective and accurate solutions, Air Monitor Power has full scalephysical flow modeling capability and in house Computational Fluid Dynamics (CFD). CFD analysis is used to analyze flowprofiles and design/redesign ductwork to improve overall performance. Full scale model fabrication and certified wind tunneltesting is used to develop application specific products that will measure accurately where no standard flow measurement can.

Pf-FLOTM – Pulverized Fuel Flow ManagementThe Pf-FLOTM system performs continuous and accurate fuel flow measurement inpulverized coal fired combustion applications, providing boiler operators with the real-timedata needed to balance coal mass distribution between burners. Balanced fuel improvescombustion efficiency and lowers emissions while reducing in-furnace slagging, coal layout,fuel slagging, and coal pipe fires.

VOLU-probe/SSTM Stainless Steel Airflow Traverse Probes.Multi-point, self-averaging, Pitot-Fechheimer airflow traverse probes with integral airflowdirection correcting design. Constructed of Type 316 stainless steel and available inexternally and internally mounted versions for harsh, corrosive or high temperatureapplications such as fume hood, laboratory exhaust, pharmaceutical, and clean roomproduction and dirty industrial process applications.


CAMSCombustion Airflow Management System


The Air Monitor Power CAMSTM – Combustion AirflowManagement System is designed to fulfill the need for areliable and accurate means of f low measurement incombustion airflow applications. Combined into a singleengineered package are the CAMMTM – Combustion Airflow

Management Module containing the microprocessor basedinstrumentation to measure the airflow and manage the purgecycle, and AUTO-purge to protect against any degradation inperformance of the duct mounted measurement device(s) dueto the presence of airborne particulate.

Product Description

CAMS – Combustion Airflow Management SystemTM

CAMMTM Performance Specification

Accuracy. ±0.1% of Natural Span, including non-linearity,hysteresis, and non-repeatability.

Stability. ±0.5% of Natural Span for six months.

Temperature Effect. Zero. None; corrected by AUTO-zero.Span. 0.015% of Full Span/ºF.

Mounting Position Effect. None; corrected by AUTO-zero.

Transducer Response Time. 0.5 second to reach 98% of astep change.

Power Consumption. 35VA at 24VAC, 20VA at 24VDC,and 42VA at 120VAC.

CAMMTM Functional Specification

Digital Output. Form "A" dry contacts (maintained) forAUTO-purge activation and acknowledgment.

Digital Inputs. External dry contact closure for AUTO-purgeexternal start and purge interrupt commands.

Analog Outputs. Four outputs for flow, temperature,absolute pressure, and special function individuallyconfigurable via jumper for 0-5VDC, 0-10VDC or 4-20mADC.

Analog Inputs. Dual inputs are field configurable via jumperfor 0-5VDC, 0-10VDC, or 4-20mADC. One is reserved fortemperature input; the other for use with optional specialfunction.

Network Communication. Optional ModBus TCP/IP overEthernet.

AUTO-purge Management. The AUTO-purge cycle isinitiated via an external dry contact input, or via the CAMMtimer, with field selectable frequencies of 1 to 24 hours in 1hour increments. A pair of CAMM dry contacts control theAUTO-purge System, and third dry contact provides remotepurge activation acknowledgment.

Power Supply. Standard 24VAC (20-28VAC) or 24VDC(20-40VDC), with automatic selection. Optional 120VAC(100-132VAC) via external UL listed transformer.

Overpressure and Static Pressure Limit. 25 psig.

Low Pass Filtration. Response time to reach 98% of a stepchange is adjustable from 2.0 to 250.0 seconds.

Automatic Zeroing. Accuracy. Within 0.1% of calibratedspan. Frequency. Every 1 to 24 hours selectable on 1 hourintervals.

Circuit Protection. Power input is fused and reversepolarity protected.

Span and Zero Adjustment. Electronic adjustment viakeypad.

Display. Backlit, graphical LCD provides indication of up tofour process variables. Triple-size digits for main processvariable, standard size characters for the other processvariables.

Temperature Compensation Selection. Push-buttonselection of linearized or nonlinear input. Choice ofthermocouple (Type E, K, J, and T) or 100 ohm platinumRTD temperature sensor type.

Pressure Compensation. Absolute pressure (atmosphereor duct static), up to 60"Hg.

Humidity Limits. 0-95% RH, non-condensing.

Temperature Limits. –20ºF to 180ºF Storage.+40ºF to 140ºF Operating.

Special Functions Power Certification Rapid Stop

Summed Flow 24VAC Standard Yes Differential Flow 24VDC NIST Traceable No

120VAC

CAMMTM Construction Options

Air Monitor Power's AUTO-purge is designed for applicationswhere the presence of airborne particulate might impair themeasurement accuracy of Air Monitor Power's CombustionAir (CA) Station or VOLU-probe array. When activated by aCAMMTM or distributed control system, a combination of fail-safe valves are operated to introduce high pressure/high

volume air to the flow measuring device's sensing ports for ashort duration while simultaneously isolating the CAMMTM fromoverpressurization. This periodic purging assists inmaintaining the sensing ports of the total and static pressuremanifolds in a clear, unobstructed condition.

Product Description

AUTO-purge

STANDARD CAPACITY

NEMA 4X Stainless Steel Enclosure Vortex Cooler. Requires 80-100 psi air supply. Rapid StopTM

Enclosure Heater. Requires 120VAC power supply. Viewing Window

Power Capacity 24VAC Standard 24VDC Low – Model SP 120VAC High – Model HP

Optional Construction

Dimensional Specifications

Brass and Copper Construction• All wetted tubing, fittings, and valves constructed of copper

and/or brass.• Enclosure is NEMA 4 painted steel.• External connection fittings are stainless steel FPT.

Stainless Steel Construction• All wetted tubing, fittings, and valves constructed of 316

stainless steel.• Enclosure is NEMA 4 painted steel.• External connection fittings are stainless steel FPT.

Standard Construction

BOTTOM VIEW

INTERIOR VIEW

AUTO-purge

Sequence of Operation

Automatic purging at regular field selectable intervals utilizesshort duration, high pressure (up to 125 psig) air to maintainsignal lines and the sensing orifices of the total and staticpressure manifolds in a clean, unobstructed condition. For theduration of the purge cycle the CAMM maintains the lasttransmitted process outputs. At the start of the purge cycle theCAMM first activates solenoid purge valves to isolate thetransmitter from the signal lines, then energizes a separate mainair purge valve, allowing the high pressure purge air to flowthrough the shuttle valves, flushing out all particulatecontaminants in the signal ports of the airflow station or probearray.

At the end of the timed purge cycle or upon receipt of a purgeinterrupt signal the CAMM first de-energizes the main air valveto shut off the supply of compressed air, followed by a shortperiod to allow the pressures in the signal lines to bleed downto process levels, then the purge valves are shuttled to reconnectthe CAMM to the process signal lines. The final step in thesequence releases the output signal hold, allowing theresumption of transmitting active process information.

Purge Frequency & Cycle Management

Installation Guide

Accumulator Tank (strongly recommended)

• Requires coalescing filter, pressure regulator, and checkvalve at the tank inlet.

120 gallons – All CA stations.

120 gallons – Multiple VOLU-probes having a combinedlength greater than 10'.

80 gallons – One or more VOLU-probes having acombined length less than 10'.

Line from Accumulator Tank to AUTO-purge Panel

• 25' maximum length, 1/2" pipe (minimum).

• Recommend locating accumulator tank as close aspossible to CAMSTM Panel.

Electrical Power Requirement

• 35VA at 24VAC; 20VA at 24VDC; 42VA at 120VAC.

• 120VAC, 10 amp when an optional enclosure heater isinstalled.

Air Requirement

• 80 to 125 psig at 100 CFM, oil and dirt free.

Line Size

• If the distance from the CAMSTM Panel to Flow MeasuringStation or Probes is less than 25', tube size to be 1/2" O.D.Wall thickness no greater than 0.065".

• If the distance from the CAMSTM Panel to Flow MeasuringStation or Probes is 25' to 50', tube size to be 3/4" O.D.Wall thickness no greater than 0.065".

• If the distance from the CAMSTM Panel to Flow MeasuringStation or Probes is greater than 50', tube size to be 1.0"O.D. Wall thickness no greater than 0.065".

Ambient Temperature

• 40ºF to 140ºF.

• For ranges above or below this ambient temperature, theuse of an enclosure heater and/or cooler is required.

The CAMM can be configured to fully manage both the frequencyand duration of the purge cycle, or allow the DCS to controleither. When operating independently, and depending upon theconcentration of airborne particulate, the frequency of purge isuser selectable via set-up menu to activate as infrequently asonce every 24 hours, or as often as hourly. In a similar mannerthe active purge duration is adjustable from 30 to 150 seconds,while the combined purge plus recovery cycle is adjustable from60 seconds to 10 minutes.

The CAMM can also be configured to allow the DCS to determinethe frequency or scheduling of the purge cycle, by means ofproviding a dry contact purge start input to the CAMM. Aseparate purge interrupt dry contact input from the DCS willtrigger the CAMM to terminate the purge cycle and return tonormal operation. When equipped with optional Rapid StopTM

valving, the resumption of active process measurement can bereduced from a typical 30 seconds to as short as 5 seconds.

CAMM – Combustion Airflow Management ModuleTM


Features

ModBus Network Communication. Each analog input andoutput signal can be individually configured for 0-5VDC, 0-10VDCor 4-20mADC by means of a single jumper.

High Turndown Ratio Operation. The CAMMTM, with its highlevel of accuracy and automatic zeroing circuitry, can maintainlinear output signals on applications requiring flow measurementturndown of 10:1.

Primary Signal Noise Filter. To eliminate background noise andpulsations from the flow signal, the CAMMTM is equipped with auser selectable digital low pass filter.

Air Density Correction. The CAMMTM is capable of performingdensity compensation for both air temperature and air pressurevariations. Temperature input is an analog signal from a remotetemperature transmitter; non-linear temperature inputs can belinearized by the microprocessor. Process pressure is measuredby means of an internal absolute pressure transducer connectedto the transmitter static pressure signal input.

Optional Rapid StopTM. The Rapid StopTM valving combined withpurge sequence timing in the CAMMTM permits a reduction of therecovery portion of an AUTO-purge cycle from a typical 30 secondsto as short as 5 seconds.

Built-In Characterization Function. For installations requiring afield characterization factor (K-factor) the CAMM has an integral"K-factor" calculator with gain and/or bias, or multi-order polynomialfunction to accurately match field testing results throughout flowturndown.

Accuracy. The CAMMTM is designed to maintain a measurementaccuracy of ±0.1% of Natural Span. For a span of 0 to 0.05 INw.c., this accuracy is equivalent to an output accuracy of ±0.00005IN w.c. differential pressure or ±0.45 FPM velocity at Natural Span.

Continuous Display of Process. All CAMMsTM are equippedwith a large multi-line, backlit, graphical LCD for use duringtransmitter configuration and calibration, and to display multiplemeasured process variables (Flow, Temperature, AbsolutePressure, Differential Pressure, or Special Function). For highvisibility, the main process variable (flow) is displayed with easy-to-read, triple-size digits. Other process variables are displayedwith standard size digits. Each measured process variable isindividually scalable in user selectable engineering units.

Special Functions Capability. Built into the CAMMTM micro-processor is the capability to perform special application functionsinvolving two transmitters. Using a second transmitter as an input,the CAMMTM can compute the sum of, or differential between thetwo measured flows. The special function output can be bothdisplayed and provided as an analog output signal.

Microprocessor Based Functionality. The CAMM'sTM on-boardmicroprocessor performs the functions of operating parameterselection, transmitter configuration, input/output and display signalscaling, density correction, and transducer calibration.

Keypad. A cover mounted keypad provides instant access to allCAMM configuration menus and calibration functions. The durablemembrane keypad is user configurable for password protection

Hinged removabletop cover

External, unitaryplug-in terminalstrips for field

wiring connections

ON-OFF power switch

Graphical backlit LCD

Aluminum NEMA 1enclosure

Cover mountedmembrane keypad

pmiyaoka

pmiyaoka

pmiyaoka

125-009-00 (2/13)



IBAMTM – Individual Burner Airflow MeasurementThe IBAMTM – Individual Burner Airflow Measurement probe is ideally suited for new orretrofit applications where a reduction in plant emissions and improvement in efficiencycan be obtained through accurate measurement of burner secondary airflow. The IBAMTM

probe has been designed to accurately measure in the particulate laden, high operatingtemperature conditions found in burner air passages.

CEMSTM – Continuous Emissions Monitoring SystemAir Monitor Power's CEMSTM – Continuous Emissions Monitoring Systems assist incomplying with the Clean Air Act’s stringent emission measurement standards and therequirements of 40 CFR 75. Air Monitor has assembled a cost effective integrated systemconsisting of in-stack flow measurement equipment and companion instrumentation toprovide continuous, accurate, and reliable volumetric airflow monitoring of stacks and ductsof any size and configuration.

CATM – Combustion Airflow Measuring Station & VOLU-probe/SSTM

Traverse Probes. Air Monitor Power's duct mounted airflow measurement deviceshave been designed to accurately and repeatedly measure air mass flow in power plants.The Combustion Air (CA) StationTM includes honeycomb air straightener to accuratelymeasure in shorter straight duct runs than any other flow measurement device. The VOLU-probe/SSTM delivers accurate airflow measurement performance in the form of an insertionprobe. Both devices feature Type 316 stainless steel flow sensing arrays.

Engineering & Testing Services. Air Monitor Power offers complete engineering and testing to analyze air and coaldelivery systems. Air Monitor Power’s field testing services use 3D airflow traversing and Pf-FLO coal flow measurementsystems for the highest possible accuracy. To ensure cost effective and accurate solutions, Air Monitor Power has full scalephysical flow modeling capability and in house Computational Fluid Dynamics (CFD). CFD analysis is used to analyze flowprofiles and design/redesign ductwork to improve overall performance. Full scale model fabrication and certified wind tunneltesting is used to develop application specific products that will measure accurately where no standard flow measurement can.

Pf-FLOTM – Pulverized Fuel Flow ManagementThe Pf-FLOTM system performs continuous and accurate fuel flow measurement inpulverized coal fired combustion applications, providing boiler operators with the real-timedata needed to balance coal mass distribution between burners. Balanced fuel improvescombustion efficiency and lowers emissions while reducing in-furnace slagging, coal layout,fuel slagging, and coal pipe fires.

VOLU-probe/SSTM Stainless Steel Airflow Traverse Probes.Multi-point, self-averaging, Pitot-Fechheimer airflow traverse probes with integral airflowdirection correcting design. Constructed of Type 316 stainless steel and available inexternally and internally mounted versions for harsh, corrosive or high temperatureapplications such as fume hood, laboratory exhaust, pharmaceutical, and clean roomproduction and dirty industrial process applications.


VELTRON DPT-plusMicroprocessor Based Ultra-Low Range

Pressure & Flow "Smart" Transmitter



The VELTRON DPT-plus transmitter is furnished with anautomatic zeroing circuit capable of electronically adjustingthe transmitter zero at predetermined time intervals whilesimul-taneously holding the transmitter output signal.

The automatic zeroing circuit eliminates all output signal driftdue to thermal, electronic or mechanical effects, as well asthe need for initial or periodic transmitter zeroing. Fortransmitters operating in a moderately steady temperaturelocation (thus no thermally induced span drift), this automatic

with Automatic Zeroing Circuit

VELTRON DPT-plus

Indication

Display. A backlit, graphical LCD providing three lines ofdata display. Also used for programming.

Inputs/Outputs

Analog Inputs. Differential pressure (high and low), and 4-20mA, 2-wire, internally or externally loop poweredtemperature signal.

Analog Outputs. Dual 4-20mA outputs, individuallyconfigurable as internally powered/non-isolated, or externallypowered/isolated.

Digital Inputs. Digital contacts for AUTO-purge external start.

Digital Outputs. Dual Form A dry contacts rated for 3 ampsat 24VAC/VDC for optional HI/LO alarm; or dual Form A drycontacts for AUTO-purge activation and acknowledgment.

Temperature Compensation Selection. Pushbuttonselection of linearized or non-linear temperature transmitterinput for the following temperature sensing types:

Type E –50 to 1750ºF –50 to 950ºC

Type T –50 to 750ºF –50 to 400ºC

Type J –50 to 2000ºF –50 to 1090ºC

Type K –50 to 2000ºF –50 to 1090ºC

RTD –50 to 1500ºF –50 to 815ºC

PowerPower Supply.Standard 24VAC (20-28VAC) or 24VDC (20-40VDC).Optional 120VAC (100-132VAC), via external transformer.

Power Consumption.Standard: 18VA at 24VAC; 13VA at 24VDC; 36VA at120VAC. With AUTO-purge Management: 54VA at 24VAC;48VA at 24VDC; 108VA at 120VAC.

Circuit Protection. Power input is fused and reversepolarity protected.

Transmitter

Accuracy. 0.1% of Natural Span, including hysteresis,deadband, non-linearity, and non-repeatability.

Type. Differential pressure, flow, and mass flow.

Ranges. Natural Spans Bi-Polar Natural Spans0 to 25.00 IN w.c.0 to 10.00 IN w.c. –10.00 to 10.00 IN w.c.0 to 5.00 IN w.c. – 5.00 to 5.00 IN w.c.0 to 2.00 IN w.c. – 2.00 to 2.00 IN w.c.0 to 1.00 IN w.c. – 1.00 to 1.00 IN w.c.0 to 0.50 IN w.c. – 0.50 to 0.50 IN w.c.0 to 0.25 IN w.c. – 0.25 to 0.25 IN w.c.0 to 0.10 IN w.c. – 0.10 to 0.10 IN w.c.0 to 0.05 IN w.c. – 0.05 to 0.05 IN w.c.

Span Rangeability. The calibrated span can be downranged to 40% of the Natural Span.

Stability. ±0.5% of Natural Span for six months.

Temperature Effect. Zero. None; corrected by AUTO-zero. Span. 0.015% of Natural Span/ºF.

Mounting Position Effect. None; corrected throughtransmitter automatic zeroing.

Span and Zero Adjustment. Digital, via internally locatedpushbuttons.

Low Pass Filtration. Response time to reach 98% of astep change is adjustable from 2.0 to 250.0 seconds.

Overpressure and Static Pressure Limit. 25 psig.

Automatic Zeroing.Accuracy. Within 0.1% of calibrated span.Frequency.Every 1 to 24 hours on 1 hour intervals.

Temperature Limits.–20 to 180ºF Storage; +32 to 140ºF Operating.

Humidity Limits. 0-95% RH, non-condensing.

Performance Specifications

zeroing function essentially produces a "self-calibrating"transmitter. The automatic zeroing circuit will re-zero thetransmitter to within 0.1% of its operating span; for atransmitter with a 0.02 IN w.c. operating span, this representsa zeroing capability within 0.00002 IN w.c.

To permit manual calibration of the VELTRON DPT-plus, anelectronic switch is provided to permit manual positioning ofthe zeroing valve.


Ultra-Low Differential Pressure & Flow "Smart" Transmitter

Accuracy. The VELTRON DPT-plus is designed to maintainan accuracy of 0.1% of Natural Span. For a span of 0 to 0.05IN w.c., this accuracy is equivalent to an output accuracy of±0.00005 IN w.c. differential pressure or ±0.90 FPM velocity.

Microprocessor Based Functionality. The VELTRON DPT-plus on-board microprocessor performs the functions ofoperating parameter selection, transmitter configuration, input/output and display signal scaling, and transducer calibration.Imbedded software performs span, flow, and 3-point "K" factorcalculations. Input to the microprocessor is via pushbuttons.

Electronic Respanning. The VELTRON DPT-plus operatingspan can be electronically selected anywhere between theNatural Span and 40% of Natural Span, without having toperform recalibration involving an external pressure source.

Air Density Correction. The VELTRON DPT-plus is capableof accepting a process temperature input to perform densitycorrection to volumetric or mass flow. Temperature input is a4-20mA signal from a remote temperature transmitter; non-linear temperature inputs can be linearized by themicroprocessor. Temperature sensor type is softwareselectable from the following choices: Thermocouple typesE, T, J, and K; or Platinum RTD.

High Turndown Ratio Operation. The VELTRON DPT-plus,with its high level of accuracy and automatic zeroing circuitry,can maintain linear output signals on applications requiringvelocity turndown of 10 to 1 (equal to a velocity pressureturndown of 100 to 1).

Features

Continuous Display of Process. The VELTRON DPT-pluscomes equipped with a multi-line, backlit, graphical LCD foruse during transmitter configuration and calibration, and todisplay multiple measured processes in engineering units.The LCD provides one line having 8 digits with double wideand double high characters, two 20 digit lines having standardsize characters, and various descriptors for transmitteroperating status.

Primary Signal Noise Filter. To eliminate background noiseand pulsations from the flow signal, the VELTRON DPT-plushas a user selectable low pass digital filter.

AUTO-purge Management (optional). For "dirty air"applications requiring the use of an Air Monitor AUTO-purgesystem, the VELTRON DPT-plus provides the capabilities ofestablishing purge frequency and duration while giving theuser a choice of either internally timed cycle frequency orexternally triggered purge initiation. During the purge cycleall transmitter outputs are maintained at their last value priorto the start of the purge cycle.

Hazardous Locations. The VELTRON DPT-plus is FactoryMutual approved for the following:• Explosion Proof: Class 1, Division 1, Groups B, C, D.• Dust Ignition Proof: Class II, III, Division 1, Groups E, F, G.• Suitable for indoor and outdoor NEMA Type 4X hazardous

locations.

Enclosure. The VELTRON DPT-plus is packaged in a NEMA4X enclosure with standard industrial process connections.

High port1/4–18 NPT for

pressure connection

3/4–14 NPT conduitconnections (2places)

NEMA 4XField wiringend

Low port 1/4–18 NPTfor pressureconnection

7.88(Max)

2Z\,

6.75(Max)

4.50(Max)

Standard LCDGraphical Display

Locknut

Calibration Port

Process Connections. Industry standard 1/4"-NPT portson 2-1/8" centers on flanges. 1/2"-NPT ports on bottom ofbase.

Electrical Connections. Dual 3/4" conduit connections.Terminal strip for field wiring and test points. External terminalstrip with plug-in connectors.

O-Rings. BUNA N.

Physical Specifications

Electrical Enclosure. NEMA 4X aluminum body withNeoprene gaskets.

Paint. Polyurethane with epoxy primer.

Mounting. Flat and angle mounting brackets for 2" pipe.

Weight. 10.5 lbs.

125-025-00 (1/00)

VELTRON DPT-plus

Suggested Specification

The mass flow transmitter shall be capable of receiving flowsignals (total and static pressure) from an airflow station orprobe array equipped with a temperature sensing means,internally perform density correction for the processtemperature, and produce individual outputs linear and scaledfor standard air volume or mass flow, and temperature.

The mass flow transmitter shall contain an integral graphicLCD for use during the configuration and calibration process,and be capable of indicating multiple process parameters(temperature, flow, dp, etc.) during normal operating mode.All transmitter parameter setting, zero and span calibration,and display scaling will be performed digitally in the on-boardmicroprocessor via input pushbuttons.

The mass flow transmitter will be available in multiple naturalspans covering the range of 0.05 IN w.c. to 10.0 IN w.c. with

an accuracy of 0.1% of natural span. The transmitter shall befurnished with a transducer automatic zeroing circuit and becapable of maintaining linear output signals on applicationsrequiring 10 to 1 velocity (100 to 1 pressure) turndown. Thetransmitter shall be capable of having its operating spanelectronically selected without having to perform recalibrationinvolving an external pressure source.

(Optional) The transmitter will provide the means of managinga system for automatic high pressure purge of the airflowstation or probe array, with user selectable purge frequencyand duration, while maintaining the last transmitter outputduring the purge cycle.

The mass flow transmitter shall be the VELTRON DPT-plusas manufactured by Air Monitor Corporation, Santa Rosa,California.

Mounting Configurations with Optional Brackets

Angle Mount to Horizontal Pipe Vertical Mount to Horizontal Pipe Mount to Horizontal Channel

Mount to Flat SurfaceVertical Mount to Vertical Pipe

Note: Mounting bracket kit includes3/8-16 U-bolt, nuts, and washers for2" Schedule 40 pipe, plus 4 bolts andwashers to attach the transmitter tothe mounting bracket.

P.O. Box 6358 • Santa Rosa, CA 95406 • P: 800-AIRFLOW • F: 707-526-9970www.airmonitor.com • [email protected] AIR MONITOR

P O W E R D I V I S I O N


Pf-FLO IIIPulverized Coal Flow Measurement

The Pf-FLO III pulverized coal flow measurement system, introducedin 1999, provides reliable and accurate mass flow measurementin pulverized coal flow applications. The system provides boileroperators with real time data of the amount of coal to each burner.Analogous to the automotive industry, the Pf-FLO III system enablescoal fired power plants to advance beyond carburetion to fuelinjection.

Coal fired boilers require accurate pulverized fuel flowmeasurement to balance coal mass distribution between burners.Balancing the coal mass improves the burner-to-burner

stoichiometry, resulting in better plant performance and operatingefficiency. Equal coal mass distribution also reduces fuel deliveryissues, such as in-furnace slagging, coal layout, fuel slugging,and coal pipe fires.

When Pf- FLO III is coupled with individual burner airflowmeasurement, a boiler operator can use the system to fine tuneair-to-fuel ratios on a per burner basis. This makes the Pf-FLO IIIsystem a very capable NOx reduction and boiler performanceoptimization tool.

Product Description

Pf-FLO III TM

♦♦♦♦♦ Real time on-line pulverized coal flow measurement

♦♦♦♦♦ 5% accuracy, independently tested, and proven

♦♦♦♦♦ System measures full pipe cross-section

♦♦♦♦♦ Simple Commissioning. No need for extractive sampling or fieldtesting to calibrate

♦♦♦♦♦ Ensures safe boiler operation by detecting fuel delivery problems

♦♦♦♦♦ Assists in minimizing primary air while maintaining minimumtransport velocity, to reduce CO emissions

♦♦♦♦♦ Industrial construction for long term durability

♦♦♦♦♦ Combustion optimization tool proven to increase efficiencyand reduce emissions

♦♦♦♦♦ Replaces manual methods of coal flow measurement

Performance Features

Velocity Measurement

Pulverized Coal Flow Measurement

The Pf-FLO III system utilizes a passive, cross-correlation methodto measure coal particle velocity in the pipe. The coal particlestravelling in the coal pipe produce a unique "signature" detected byboth the upstream and downstream Pf-FLO sensors.

These "signatures" are subjected to cross correlation processingto determine the time of flight (∆t) required for the signature topass from the upstream sensor to the downstream sensor. Thetime of flight combined with the known distance between sensorsproduces the coal particle velocity.

The Pf-FLO III system measures coal density via the relationshipbetween signal frequency shift and the amount of pulverized coalpresent in the pipe. An increase in coal density produces ameasured shift of the microwave resonant signal to a lowerfrequency.

This shift in resonant frequency is calculated with a patented(U.S. Patent Nos. 6,109,097 and 6,771,080) dual slope measurementalgorithm and correlated to coal density.

Density Measurement

How It Works

The Pf-FLO III system determines the mass flow of pulverized coalbeing transported in a pipe by independently measuring thecomponents of coal velocity and density . The system uses apassive method to determine coal particle velocity, while the coaldensity measurement uses a microwave based technology.

The Pf-FLO III system is comprised of a transmitter , sensors,reflector rods, and sensor cabling. The transmitter mounts nearthe measurement zone on the coal pipe and performs all processingrequired to calculate the coal density, velocity, and mass flow. Thepipe mounted density , velocity, and temperature sensors areconnected to the transmitter with provided factory preparedcabling. The reflector rods are installed upstream and downstreamof the sensors. The section of pipe within the sensors functions

as a wave guide, along which the microwave signal can propagate.The reflector rods are installed to prevent reflected microwavesfrom entering back into the measurement zone between sensors.Reflected microwaves can interfere with the density measurementin the form of microwave “noise”.

The Pf-FLO III transmitter provides direct coal velocity and massflow outputs to the DCS via 4-20mA signals, plus an Ethernetconnection to the PC which is used for data acquisition, datahistorian, system commissioning, and configuration.

The drawing below illustrates the typical configuration for pipemounted components. There are four reflector rods and twosensors per pipe.

Pf-FLO Features

Pf-FLO III TM

Stand-Alone Measurement. Each Pf-FLO III coal flow transmitterdetermines the mass flow rate and particle velocity of pulverizedcoal, independent of a central processor and/or external inputssuch as mill feeder rate. The onboard microprocessor managesthe transmitter functionality and performs all data processing,providing reliability with real-time performance.

Data Acquisition. The Pf-Vu data acquisition and archival softwareprovides the system operator with both dynamic and historicgraphical presentations of all measured parameters (particlevelocity, density, mass flow rate, and pipe temperature), logicallyarranged by mill. Data can be selectively exported numerically intospreadsheet software [in a delimited format] and/or continuouslycommunicated via an OPC or Modbus interface directly to a DCS orPI platform.

Long Term Durability. All in-pipe mounted component s areconstructed of abrasion resistant Tungsten Carbide to ensure longlife, and are backed with a three year warranty.

Analog Communication. The Pf-FLO III transmitter providesdual 4-20mADC analog outputs for mass flow rate and particlevelocity measurements, user configurable for isolated or non-isolated operation.

Local, Central & Remote Configuration. Utilizing the Pf-PROsoftware utility, parameterization and calibration of each Pf-FLO IIItransmitter can be performed from a central PC over industrystandard Ethernet wiring, or locally at each transmitter utilizing alaptop computer and a direct connect cable. With the addition of aphone connection to the central PC, each transmitter can bemonitored and configured remotely.

Simplified Installation. Included weld-in threaded inserts forpipe mounted components, plus Factory prepared and labeled cablesprovide for fast and error free installation of the Pf-FLO III coalflow system. Cable lengths of up to 50’ allow for flexibility in themounting location of each transmitter’s NEMA 4 enclosure.

Pulverized Coal Flow Measurement

System Architecture

Pf-FLO III TM

Pf-Vu software provides access to all system parameters (massflow, velocity, density, and temperature) for each mill.

Pf-Vu Features

Dynamic and historical data trending can be viewed through thePf-Vu interface.

Screen Selection Dynamic Trend


♦♦♦♦♦ Suitable for installation in vertical, inclined or horizontal pipe.

♦♦♦♦♦ Recommended installation in vertical section of pipe right out ofmill discharge or first horizontal section of pipe within three tofive diameters of the upstream elbow.

♦♦♦♦♦ Pipe must not have any flanges in the measurement zone.

♦♦♦♦♦ Test ports can be located anywhere except in the measurementzone between the two sensors.

♦♦♦♦♦ Fixed or variable orifices and coal valves must be located outsidethe reflector rods.

♦♦♦♦♦ Orifices and coal valves should be installed downstream of thelast reflector rod.

♦♦♦♦♦ Pipe must not have ceramic lining within the reflector rods.

♦♦♦♦♦ Vertical down flow is not a suitable installation for the Pf-FLO IIIsystem.

Pf-FLO IIITM Performance Specification

Accuracy±5% of mass flow (absolute units), combining velocity anddensity accuracies.

Power Consumption42 VA at 120 VAC24 VA at 24 VAC/DC

Measurement Update RateSingle Pipe System. Mass Flow: 2 to 3 secondsDual Pipe System. Mass Flow: 4 to 6 seconds

Pf-FLO IIITM Functional Specification

Microprocessor Based FunctionalityAll functions and operations are performed by thePf-FLO IIITM system on-board microprocessor.

Pf-FLO IIITM to PC / DAS ConnectivityModBus / TCPIP via Ethernet

Analog OutputsDual 4-20mADC isolated or non-isolated outputs Output 1: Mass Flow Output 2: Velocity

Analog InputsIsolated or non-isolated 4-20mADC inputs for mill feed rateand mill primary airflow. Inputs are for data analysis onlyand are not required for mass flow measurement.

Rolling Average FilterAdjustable from 1 to 10 values

Velocity Measurement Range20 to 200 ft/s

Pipe Temperature Measurement Range0 to 300ºF

Density Measurement Range0 to 200 absolute units (approximately 0 to 0.08 lb/ft3,dependent upon coal type)

Power Supply Requirement120 VAC, 24 VAC or 24 VDC

Circuit ProtectionPower input is fused and reverse polarity protected

Temperature Limits.–20ºF to 180ºF Storage 0ºF to 140ºF Operating

EnclosureNEMA 4

Sensor Antenna and In-Pipe ComponentsTungsten carbide construction

Threaded InsertsWeld-in 5/8-18

Pf-FLO III TM

Pf-FLO IIITM PC/DAS Functional Specification

Pf-VuWonderwareTM based software for data display andextraction to ExcelTM. [Optional] Pf-Vu/Plus to includeBurner Secondary Airflow Measurement.

Pf-PROSystem management software for local or central systemparameterization and commissioning.

Data StorageReceive and archive data for all pipes: Density, Velocity,Temperature, Mass Flow, Feeder, and PA.

Data Extraction[Optional] OPC or Modbus communication of data to plantDCS or PI system.

Remote ConnectivityPCAnywhereTM for remote operator access. Requiresphone connection.

Password ProtectionOwner, Administrator, and Operator / User.

125-196 (7/07)

Air Monitor Power's Product Families of Airflow Measurement & Services

IBAMTM – Individual Burner Airflow MeasurementThe IBAMTM – Individual Burner Airflow Measurement probe is ideally suited for new orretrofit applications where a reduction in plant emissions and improvement in efficiencycan be obtained through accurate measurement of burner secondary airflow. TheIBAMTM probe has been designed to accurately measure in the particulate laden, highoperating temperature conditions found in burner air passages.

CAMSTM – Combustion Airflow Management SystemThe CAMSTM – Combustion Airflow Management System has been designed to reliablyand accurately measure airflow in combustion airflow applications. The CAMSTM

contains the microprocessor based instrumentation to measure the airflow andmanage the AUTO-purge. The AUTO-purge is a high pressure air blowback systemthat protects the duct mounted flow measurement device from any degradation inperformance due to the presence of airborne particulate (flyash).

Air Monitor Power's duct mounted airflow measurement devices have been designedto accurately and repeatedly measure air mass flow in power plants. The CombustionAir (CA) StationTM includes honeycomb air straightener to accurately measure in shorterstraight duct runs than any other flow measurement device. The VOLU-probe/SSTM

delivers accurate airflow measurement performance in the form of an insertion probe.Both devices feature Type 316 stainless steel flow sensing arrays.

CEMSTM – Continuous Emissions Monitoring SystemAir Monitor Power's CEMSTM – Continuous Emissions Monitoring Systems assistin complying with the Clean Air Act’s stringent emission measurement standardsand the requirements of 40 CFR 75. Air Monitor Power has assembled a costeffective integrated system consisting of in-stack flow measurement equipmentand companion instrumentation to provide continuous, accurate, and reliablevolumetric airflow monitoring of stacks and ducts of any size and configuration.

Combustion Airflow Measuring Station & VOLU-probe/SSTM Traverse Probes

Engineering & Testing Services. Air Monitor Power offers completeengineering and testing to analyze air and coal delivery systems. Air MonitorPower’s field testing services use 3D airflow traversing and Pf-FLO coal flowmeasurement systems for the highest possible accuracy. To ensure costeffective and accurate solutions, Air Monitor Power has full scale physicalflow modeling capability and in house Computational Fluid Dynamics (CFD).CFD analysis is used to analyze flow profiles and design/redesign ductworkto improve overall performance. Full scale model fabrication and certifiedwind tunnel testing is used to develop application specific products that willmeasure accurately where no standard flow measurement can.

Coal Flow Technology Licensed From:

P.O. Box 6358 • Santa Rosa, CA 95406 • P: 800-AIRFLOW • F: 707-526-9970 • www.airmonitor.com • [email protected]

-i-

N O X R E D U C T I O N T H R O U G H C O M B U S T I O N O P T I M I Z A T I O N O N A 4 2 0 M W W A L L - F I R E D U N I T A T

P R O G R E S S E N E R G Y

A U T H O R S : P E T E R H O E F L I C H – P R O G R E S S E N E R G Y

D A V E E A R L E Y, A M C P O W E R / C O M B U S T I O N T E C H N O L O G I E S C O R P.

Abstract

As a result of increasingly stringent emissions limitations being imposed on coal-fired power plants today, electric utilities are faced with having to make major compliance related modifications to their existing power plants. Even when implementing the more expensive post-combustion NOx reduction programs on some larger generating units, many utilities are still finding themselves in need of further NOx reduction. This is often caused by higher than expected NOx output after the SCR is installed (often at reduced loads) and higher NOx from units that did not get SCRs. In-furnace NOx reduction offers a less expensive alternative/complement and is suitable to any size boiler to reduce NOx while also improving overall combustion. In-furnace NOx reduction strategies can also be effective year-round (not just during ozone season). Since these strategies often result in improved efficiency and elimination of some combustion problems (burner fires, slagging, mill problems, etc) these programs also lead to more reliable generation. When implemented in conjunction with an expensive post-combustion SCR program, initial capital requirements and ongoing operating costs ( i.e. ammonia consumption ) can be cut to save utilities millions of dollars. For the purpose of developing a system-wide NOx reduction strategy, Progress Energy, a southeastern U.S. utility applied pulverized coal flow measurement and control to one of its units without an SCR. The purpose of this installation was to attempt to reduce NOX by at least 10% (especially at reduced loads). Once successful, this led to the installation of a more elaborate fuel and airflow measurement and control program on a larger Progress Energy unit with a high NOx output. This control program was also combined with other “lower cost” modifications for an overall larger NOx reduction. In addition to getting over 20% NOx reduction from the combustion optimization alone, this part of the project yielded other benefits such as 40% lower LOI. How this program produced the NOx reduction and other benefits will be presented in detail in this paper. The paper will also discuss the effects on excess O2, opacity, and steam temperature.

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I. INTRODUCTION

In an effort to reduce NOx emissions at some of its plants, Progress Energy initiated a strategy of combining lower cost in-furnace NOx control technology with lower cost post combustion NOx control technology. The goal was to achieve significant NOx reduction while avoiding the higher cost of more SCRs. It has been well established that combustion tuning or optimizing can lead to NOx reduction while also helping to improve other parameters such as slagging, corrosion, LOI and more. One of the technologies selected for in-furnace NOx control was on-line pulverized coal flow measurement. In 2002 Progress Energy/Strategic Engineering developed a plan to select, test and then implement this technology for NOx control on a mid-size boiler.

II. COAL FLOW MEASUREMENT TECHNOLOGY

Several on-line coal flow measurement technologies were evaluated for performance and the one selected was Pf-FLO by AMC Power (AMC) as it is the only commercially available product that measures absolute (as opposed to relative) coal flow. Pf-FLO uses microwave technology to measure the coal density between two sensors installed in a coal pipe. It also uses electrostatic technology to simultaneously measure the velocity of the moving coal particles through cross correlation and time of flight. The product of density and velocity is mass flow. Both the mass flow and coal velocity would be critical to combustion optimization and thus NOx reduction. Review of Pf-FLO Technology To obtain the mass flow of pulverized coal being transported to a burner, one needs to know both the concentration1 and the velocity of the coal in the burner pipe. The Pf-FLO system measures both the coal concentration and velocity in each pipe, independent of both the measurements performed on the other pipes and the coal feeder information, resulting in coal velocity outputs for each pipe scaled in units of feet per second and mass flow outputs directly proportional to the coal flow in each pipe. Pf-FLO is a unique technology for online coal flow measurement in that it provides an accurate absolute measurement without need for in situ calibration. Other online coal flow measurement systems require the use of field calibration methods such as isokinetic sampling or rota-probing, which are known to be as inaccurate as ±10%. The result of utilizing these field calibration methods is a measurement system that can indicate “balanced” coal pipes when the actual mass flow distribution can vary as much as ±20%. The Pf-FLO technology, requiring no calibration, produces an extremely accurate measurement of the coal flow to each burner.

1 The term 'concentration' is meant as mass concentration or mass density in this report.

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III. TRIAL SYSTEM

Before applying the coal flow technology with the other technologies for optimum NOx reduction, a trial would be performed at the Mayo Station. Mayo consists of two boilers operating one turbine. Pf-FLO was installed in each of sixteen (16) burners for one of the two boilers. The goal was to achieve 10-15% NOx reduction using just the Pf-FLO system. This low cost trial entailed renting a Pf-FLO system for the sixteen pipes. No adjustable coal valves were purchased. The objective would be to adjust burner airflows (though no airflow measurements were available) to the burners based upon the coal mass flow in each pipe. Though no coal valves were purchased due to cost limitations for this trial, the auxiliary air on each of the four coal mills was used to act as an air curtain or restriction in each coal pipe. This allowed for better balancing of the coal pipes of each mill. Though Pf-FLO yielded the coal flow to each burner, the airflow to each burner was unknown. The O2 grid in the backpass was used in lieu of airflow to help identify fuel:air ratio imbalances. Burner air registers were adjusted accordingly. As a result, a 10% NOx reduction was achieved at full load and 15% reduction was achieved at reduced load. These tests were repeated on different days to ensure repeatable results. In addition, the improved combustion led to a reduction in opacity for all tests and O2 stratification was also minimized. Through the Mayo trials, it was determined that individual burner airflow would be helpful in future installations. Individual burner airflow would allow the users to tune airflow to match coal flows directly. In addition, a more effective means of moving coal flow between pipes was recommended.

IV. IMPLEMENTING A COMPLETE NOX CONTROL SYSTEM

Sutton 3 was selected for the integration of the “lower cost” NOx reduction systems. In addition to the air and fuel control, low NOx burner modifications and SNCR were to be implemented at Sutton. A. Coal Adjustment and Air Flow

Sutton 3 has Riley double ended Atrita mills. These mills are known to produce end to end imbalances. In addition, the output of each end of each mill would split into two pipes through a riffle box. These riffle boxes are also known to create imbalanced coal flow. Diverter dampers were designed by AMC and installed during the April-May 2005 outage. The diverter dampers controlled the coal to each side of each mill. In addition, new adjustable (for coal imbalance) riffle boxes were purchased through FWEC. AMC specializes in combustion airflow measurement and has supplied individual burner airflow measurement systems (IBAMs) on several hundred low NOx

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burners in the U.S. IBAMs were designed and tested in their wind tunnel for the Sutton 3 burners. The IBAMS were installed in the burners during the April-May 2005 outage.

B. Sutton 3 Pre-Outage Tuning – Improve Controls and Reduce NOx

Prior to the April-May 2005 outage, baseline NOx (domestic coal) was 0.70 lb/MMBtu and baseline LOI was 20-25%. In February, the AMC Pf-FLO system was installed in each of the 28 coal pipes with the goal of obtaining baseline coal flow data and possibly performing preliminary combustion optimizing. For much of March, Pf-FLO coal flow data was often “noisy”. AMC recognized this type of erratic coal flow behavior to be indicative of coal layout. After further investigation, these coal flow problems were determined to be problems/errors in the DCS programming for feeder and primary air control. As a result, new control logic was downloaded and new primary air curves were developed. Upon the downloading of the new controls software and proper PA/feeder curves (just after the outage), the coal layout and otherwise erratic flows had subsided. While burner airflow measurement systems (IBAMS) were not installed yet, burner disks were adjusted before the outage to compensate for lean and rich burners (as shown by Pf-FLO). In addition, feeders were biased for optimum NOx control. The result of this pre-outage optimization was a NOx reduction to 0.54 lb/MMBtu (24% reduction). This level was maintained for twelve hours leading up to the spring outage.

C. Post Outage Work

The controls and PA curve changes as outlined earlier were integrated just after start up. This took several weeks. After several weeks of burner tuning by FWEC, diverter damper and riffle box adjustments were performed in early June. After burner tuning and coal pipe balancing, NOx levels were reduced to 0.42 lb/MMBtu. Further tuning with Pf-FLO also optimized boiler operation for this low NOx condition by eliminating superheat and reheat temperature alarm conditions which had resulted from the burner tuning with new burner modifications. In August, diverter dampers were placed in automatic control. More tuning was performed using the IBAM data and adjusting burner disks for proper fuel/air ratios after the diverters had equalized the fuel. LOI levels were reduced from above 20% to 12.69% (over a 37% LOI reduction). In February 2006, the burner secondary air disks were put in automatic control. Three Fuel/Air setpoints strategies were developed – normal, overfire air and fuel

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rich. For each strategy, each row of burners was given a fuel/air setpoint. The controls system looks at 2-minute averages of fuel/air ratios. If a burners’ fuel/air ratio is above or below it’s setpoint by more than 10%, the secondary air disk is moved open or close accordingly by an increment of 5%. Another 2-minute average is then analyzed and changes are made accordingly.

The O2 across the back end improved and fuel air ratios are maintained. This new control scheme would mean operators will spend less time trying to “blindly” adjust burner air registers when there is a combustion problem (such as O2 imbalance or high CO).

V. RESULTS SUMMARY

The Pf-FLO coal flow system combined with the IBAM burner airflow systems, coal diverters, and riffle boxes exceeded expectations for NOx control and other combustion improvements (Better Boiler control, LOI, and O2) as outlined in the table below.

PROJECT PERFORMANCE vs. GOALS

Modification Target Measured Remarks

Coal Flow and Air Flow Balancing (Air Monitor Corporation)

NOx < 0.595 lb/mmbtu (15% reduction in NOx)

NOx = 0.54 lb/mmbtu (23% reduction from 0.7 lb/mmbtu baseline)

Measured values achieved April 21, 2005 with domestic coal. Unit at Full Load 7 mill operation (pre-outage).

Combined Coal Flow and Air Flow Balancing (Air Monitor Corporation) and Low NOx Burner Modifications (Foster Wheeler)

NOx <0.482 lb/mmbtu (34% reduction in NOx.) AMC=15% reduction in NOx FW = 19% reduction in NOx LOI < 21%

NOx = 0.42 lb/mmbtu (40% NOx reduction from 0.7 lb/mmbtu baseline) LOI = 20%

Measured values achieved June 9, 2005 with domestic coal. Unit at Full Load (VWO), 7 mill operation (post outage).

Coal Flow and Air Flow Balancing (Air Monitor Corporation)

LOI = 12.6%

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APPENDIX SUTTON 3 PROJECT

The Pf-FLO III coal flow measurement system was installed onto each of the 28 burner lines at Sutton Unit 3 in February 2005. The location of the sensors is in the horizontal pipe sections downstream of the riffle boxes. As shown below, the riffle boxes are to the lower right, the burners are to the left of the riffle boxes.

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The plant has seven double ended Riley Atrita mills. Each mill provides coal to two riffle boxes and each riffle box feeds two burners. The Riley Atrita mill has two separate ends that operate like independent milling systems. Each riffle box is supplied coal by a single pipe from one end of the mill (as shown below).

Because most of the coal imbalance is the result of the mill end-to-end imbalance, a diverted damper was engineered to control the coal flow to each end of the mill, based upon the comparison of the summed mass flow of each end (Pipes 1+2 vs Pipes 3+4).

Coal and Primary Air into mill

To Pipes 1 and 2

To Pipes 3 and 4

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Additionally, the riffle boxes were replaced with new adjustable riffle boxes having the capability to control and balance pipe-to-pipe fuel distribution without having to access the internal components.

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A. Pre-Outage Testing

For much of March, the Pf-FLO data was often “noisy”, as reflected below. This erratic behavior and coal layout was found to be the result of improper feeder and PA control. New PA and Feeder control logic was developed and implemented. The result was more stable mill operation and control.

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SUTTON 3 PROJECT

A. Pre-Outage Testing (con’t)

Improper primary air control can often result in layout of coal in the coal pipes. The plot below shows that on this mill, a decrease in load is matched by a decrease in coal velocity, resulting in unstable coal transport and coal layout. This could be corrected with higher PA at that load condition.

New Primary Air curves were developed for all mills to reduce layout and give optimum velocity for burner performance.

C MIll Pipe Velocities

0

20

40

60

80

100

120

140

160

180

11:1

5:28

11:2

3:28

11:3

1:28

11:3

9:28

11:4

7:28

11:5

5:28

12:0

3:28

12:1

1:28

12:1

9:28

12:2

7:28

12:3

5:28

12:4

3:28

12:5

1:28

12:5

9:28

13:0

7:28

13:1

5:28

13:2

3:28

13:3

1:28

13:3

9:28

13:4

7:28

13:5

5:28

14:0

3:28

14:1

1:28

14:1

9:28

14:2

7:28

14:3

5:28

14:4

3:28

14:5

1:28

14:5

9:28

15:0

7:28

15:1

5:28

15:2

3:28

15:3

1:28

15:3

9:28

15:4

7:28

M003P001VM003P002VM003P003VM003P004V

of 15

A. Pre-Outage Testing (con’t)

The result of this optimization was a NOx reduction from baseline of 0.71 lb/MMBtu to 0.54 lb/MMBtu, as shown from PI data below. This level was maintained for 12 hours prior to the Spring outage.

SUTTON 3 PROJECT

B. Post-Outage Work

Below are examples of coal pipe balance changes due to diverter damper adjustment – pipes become more balanced. After burner tuning and coal pipe balancing, NOx levels were reduced to 0.42 lb/MMBtu.

of 14

SUTTON 3 PROJECT (con’t)

C. Post NOx Reduction Tuning

In addition to the online coal flow monitors, individual burner airflow measurement (IBAMs) were installed in each of the 28 low NOx burners.

A full-scale mock up of the burner was tested for flow accuracy in AMC’s wind tunnel.

of 14

SUTTON 3 PROJECT (con’t)

C. Post NOx Reduction Tuning

The screen below is a new screen in the Sutton Control Room. This was used to develop ideal burner fuel air ratios. In August, diverter dampers were placed in automatic control. More tuning was performed using the screen below to achieve proper fuel/air ratios after the diverters moved the fuel. LOI levels were reduced from above 20% to 12.69%.

In addition the this main screen (above), new coal flwo screens were developed for the control room. By clicking on “Coal” for any mill above, the coal balance for that mill can be seen (below):

of 14

Below is the control room screen showing desired/automatic fuel/air ratios.

PF-FLO REFERENCE TEST

AT THE

MARTIN-LUTHER UNIVERSITY HALLE-WITTENBERG

Martin-Luther-Universität Halle-Wittenberg AMC Power – PROMECON

Fachbereich Ingenieurwissenschaften 1050 Hopper Avenue

Lehrstuhl für Mechanische Verfahrenstechnik Santa Rosa, California 95403

06099 Halle (Saale) U.S.A.

Germany

PF-FLO REFERENCE TEST AT THE MARTIN-LUTHER UNIVERSITYHALLE-WITTENBERG

CONTENTS Page

1. Introduction..................................................................................................... 12. Description of the Test Facilities..................................................................... 3

2.1 The Testing Plant ................................................................................... 32.2 The Pf-FLO Mass Flow Measurement.................................................... 4

2.2.1 Density measurement.................................................................. 42.2.2 Velocity measurement ................................................................. 52.2.3 Calculation of the Mass Flow....................................................... 6

2.3 Pf-FLO Test Configuration...................................................................... 62.4 The Test Medium.................................................................................... 82.5 Feeder Calibration .................................................................................. 9

3. Testing Procedure .......................................................................................... 114. Results ........................................................................................................... 14

4.1 Pf-FLO Measurement Accuracy ............................................................. 144.1.1 Absolute Deviation....................................................................... 154.1.2 Repeatability ................................................................................ 16

4.2 Influence of the Particle Size .................................................................. 174.2.1 Velocity Measurement ................................................................. 174.2.2 Density Measurement.................................................................. 194.2.3 Mass flow measurement .............................................................. 20

5. Abstract .......................................................................................................... 23

Figures PageFig. 2.1: Schematic drawing of the test plant ............................................................. 3

Fig. 3.1: Range of pf-concentrations based on feeder mass flow and transport airflow .............................................................................................................. 11

Fig. 3.2: Density measurement .................................................................................. 12

Fig. 3.3: Velocity measurement ................................................................................. 12

Fig. 3.4: Resulting mass flow and feeder signal......................................................... 12

Fig. 3.5: Mass flow of feeder versus Pf-FLO.............................................................. 12

Fig. 4.1: Evaluation of all test runs with 66 / 225 µm particles ................................... 14

Fig. 4.2: Repeatability of channel 0 for 66 - 225 µm particles .................................... 15

Fig. 4.3 Averaged particle velocities at channel 0..................................................... 17

Fig. 4.4: Acceleration along the test duct of the 225 µm particles.............................. 18

Fig. 4.5: Influence of the mass flow on the velocity of the particle mix in Test IV-VI.. 18

Fig. 4.6: Density measurement with 66 µm particles Test V. ..................................... 19

Fig. 4.7: Density measurement with 225 µm particles Test I ..................................... 19

Fig. 4.8: Influence of the particle size on the Pf-FLO measurement .......................... 20

Fig. 4.9: Estimated deviation by modeled particle size distribution............................ 22

Tables PageTable 2.1:Bulk density and frequency shift for fixed-bed powder of pulverized black

coal and glass particles................................................................................ 8

Table 3.1:Test run number for each particle size......................................................... 12

Table 4.1:Standard deviation and mean error for individual particle fractions ............. 15

Table 4.2:Standard deviation of the individual channels with 66 µm particles ............. 16

Table 4.3:Standard deviation of the individual channels with 225 µm particles ........... 16

Table 4.4:Standard deviation of the individual channels with 66-225 µm particle mix . 16

Table 4.5:Ratio of arbitrary units to mass and the resulting mass frequency factor kfd

for each particle fraction............................................................................... 21

1. Introduction

Measurement of particle concentration or mass flow rate in pipeline systems (i.e.pneumatic conveying) is essential for numerous technical applications, such asconveying of pulverized coal in power plants or conveying systems in cementfactories. Of major importance is the detection of the particulate flow in the entirecross-section of a pipe. In the past this has generally only been achieved in pipeelements where the particulate concentration is homogeneously distributed over theentire cross-section. For such a measurement different techniques are available,namely extractive methods utilizing probes and non-extractive methods employingelectromagnetic waves or particle charging. From the first inspection an isokineticsampling probe seems to be the simplest approach, however, in order to measurethe particulate flux in the entire pipe section it is necessary to systematically positionthe extraction probe at defined locations across the entire pipe cross-section. Due toprobe erosion damage, extractive sampling is only suitable for periodicmeasurement. For continuous measurement, non-extractive methods are morefavorable, where the sensing instrumentation is mounted in-situ. One approach is thedetection of the electrostatic charge of moving particles. Unfortunately, the resultingsignal is not only affected by particle concentration, but also by gas temperature andparticle velocity. The method used for the investigation documented in this report isbased on utilizing microwaves emitted and detected by screw-in sensors. Thegenerated microwave field covers the entire pipe cross-section and hence allows thedetermination of the averaged particle concentration over that cross-section. Theprinciple of the method will be outlined below.

The microwave based experiments were conducted on an air-particle flow loopestablished at the Lehrstuhl für Mechanische Verfahrenstechnik of the Martin-LutherUniversity Halle- Wittenberg. In order to consider different conveying conditions,probes were installed at multiple locations of the conveying pipe, namely in anupward flow with almost homogeneous dust distribution, behind a vertical-horizontalbend where roping is likely to occur, and in an almost fully developed state of ahorizontal pipe. The particle introduction was achieved using a calibrated screwfeeder, which also allowed the comparison of the particulate mass flow with the resultfrom the microwave instrument. Since the handling of pulverized coal could not besafely performed at the test facility, spherical glass beads of two different meandiameters were used as coal substitutes. It is acknowledged that the differentmaterial density and particle shape of the glass particles results in a slightly differentconveying behavior, primarily in the form of lower particle velocities, but otherwisethe general flow behavior of coal and glass particle is extremely similar.

This report presents a description of the test facility and the measurement principle.The measurements are presented in comparison with the calibrated screw feeder,and a detailed discussion of the accuracy achieved with the microwave instrument isprovided.

2. Description of the Test Facilities

The reference test was carried out at the Merseburg test plant. The test facility isdesigned with a closed loop for the particle flow and an open end for the transport air.This arrangement ensures particle recycling via a cyclone back to the feeder withoutsignificant particle mass loss, for re-introduction at a controlled rate/concentration.For safety reasons the test plant was operated with glass beads of two differentdiameters instead of pulverized coal. Particle load and transport air velocity werevaried during the test series in a range simulating that which naturally occurs withpneumatically transported coal (see test matrix, Figure 3.1 and Table 3.1).

2.1 The Testing Plant

The test duct layout is drawn in Figure 2.1. Two rotary piston blowers, operating inparallel and controlled by fan speed frequency converters, providing a velocity rangeof about 46 to 92 ft³/s for the transport air.

Cyclone

Rotary Valve

Screw Feeder

Bagfilter

Ch 3 Ch 2

Ch 1

Ch 0

Hopper

Air Outlet

16.5 ft.

10 ft. Air

Inle

t

Fig. 2.1: Schematic drawing of the test plant

The particles are introduced to the airflow by a screw feeder, transported through thepipe and separated in a cyclone. Out of the cyclone the separated particles are fed

by a rotary valve back into the hopper of the screw feeder. The transport air isexhausted through a bag filter.

The screw feeder is frequency controlled over a range of 0 – 350 rpm. The horizontalrun downstream of the feeder has a rectangular cross section, whereas the verticaland the upper horizontal pipes where the Pf-FLO measurements are located areround pipes having an inner diameter of 4.86”.

The airflow velocity is measured by a multi-point Pitot probe positioned upstream ofthe feeder. In addition, the airflow static pressure and temperature are alsomonitored.

2.2 The Pf-FLO Mass Flow Measurement

The Pf-FLO system independently measures the density and velocity of pulverizedfuel in a two-phase flow. After a “zero” calibration of the empty transport pipe isperformed for the density measurement process, absolute mass flow can becalculated using the product of the separate density and coal velocity signals.

2.2.1 Density measurement

Using the pipe as a wave-guide, the particulate concentration or density is measuredwith transmitted microwaves that cover the full cross section of the pipe. Startingwith the known microwave transmission characteristic determined during empty pipezeroing, the varying dielectric load caused by changing pulverized fuel (pf)concentrations produces a measurable frequency shift. The basics of thismeasurement can be described as follows1):

The cut-off frequency (λcut) of a round wave-guide is in this application the frequencyof the H11 mode. The wavelength of the H 11 mode is a function of the diameter of thepipe.

Equation 1.

wherein D is the diameter of the pipe and X’mn is the solution of theBessel function.

1) Kummer: Grundlagen der Mikrowellentechnik, chapter 3.4 and 4.3; Berlin: 1986

DD

mncut ⋅=

Χ′⋅

= 71.1π

λ

The frequency (ƒ) of the H11 mode depends on the dielectric εr and the magnetic µr

properties of the volume in the wave-guide.

Equation 2. where c is the constant for the speed of light

An unloaded pipe filled with air has a εr of 1 and a µr of 1. Hard coal has an εr of 4and µr of 1. The volumetric ratio of pulverized coal to air at a coal concentration of0.0312 lb/ft³ is 1 to 2500. Since the resulting εr changes between loaded and emptypipe in terms of 1/2500 the series expansion of Equation 2 can be used with its linearterm. This gives a linear relation between the frequency and pf load within theconcentration range typically found in coal fired power plants.

The Pf-FLO system couples microwaves in the range of the cut-off frequency into apipe section using a pair of sensors, one sensor functioning as the transmitter and asecond sensor as the receiver. The exact frequency of the H 11 mode is calculated byscanning the transmitted microwave signal amplitudes.

A change in the concentration of pf in a given pipe changes the measured microwavefrequency: The higher the concentration, the lower the frequency. The frequency shiftcaused by the pf is calculated by subtracting the frequency fε of the loaded pipe fromthe frequency f0 of the empty pipe. This frequency shift is transformed into a densitysignal (ρ) by the frequency density factor kfd.

Equation 3.

Where f0 is determined by the empty pipe zeroing process.

Changes in pipe diameter caused by temperature do affect the measured frequency.Temperature compensation of the measured frequency uses the pipe surfacetemperature and the linear expansion factor for that pipe material.

2.2.2 Velocity measurement

The velocity measurement uses a cross-correlation method for comparing thestochastic signals of the electrostatic charged particles at two sensor locations ofknown separation (see Figure 2.2). An evaluation of the velocity sensor signals givesthe time shift or time of flight (τm). Using the distance between the sensors (L), solidparticle velocity (vs) can be calculated as follows:

Equation 4.

( ) fdkff ⋅−= ερ 0

cutrr

cf

λµε ⋅=

ms

Lv

τ=

By using this method only particle velocity is measured, which in most instancesdiffers from and is slower than the transport air velocity in a two-phase flow. Thisdifference, or velocity slip, is a function of such factors as pipe configuration, specificweight and size of particles.

Signal 1

Signal 2

Cross-correlation

Fig. 2.2: Velocity measurement principle: signals andresulting cross-correlation function

2.2.3 Calculation of the Mass Flow

The mass flow is calculated from the density and the particulate velocity

measurement as follows:

Equation 5.

The Pf-FLO system is calibrated to a known mass flow of the mill or pipe by adjustingthe frequency density factor kfd in Equation 3, which in turn depends on the pipediameter. The factor kfd is kept constant for all pipes with the same diameter.

2.3 Pf-FLO Test Configuration

The 4.86” diameter test duct pipe has a cut-off frequency of approximately 1.4 GHz.The standard microwave generating unit of the Pf-FLO system has been selected toprovide frequencies up to only a 1 GHz level required for the range of larger coal pipe

svdtdm

⋅= ρ

dtdm

Velocity = L / τm

5.25 D

rod

sensor

0.87 D 1.0 D 0.75 D 0.75 D 1.0 D 0.87 D

dtdm

sizes found in power plants. For the test runs conducted it was necessary to replacethe standard model generator with a similar model having an extended frequencyrange of up to 2.0 GHz.

Corresponding to the smaller inner diameter of the test duct, the sensor antenna wasalso scaled down in length. Distances between sensors and rods in the test runswere the standard distances based on a pipe having a diameter D, as show in Figure2.3.

Fig. 2.3: Arrangement of sensors and rods at individual measurement locations

The Pf-FLO system uses wear resistant Tungsten Carbide rods to keep thepropagation of the microwaves within the certain measurement zone of the pipe.Without the rods, the density measurement would be disturbed by reflected signalscaused by pipe bends, orifice plates, isolation valves, etc., located upstream and/ordownstream of the measurement zone. The optional fifth rod perpendicular to thesensors and located at their midpoint provides an additional signal short cut fordepressing the propagation of 90° polarized H11 modes.

Without knowing the actual mass frequency factor for the test pipe size, all channelswere initially set to

This factor was kept constant for all measurements in the test. The resulting units for

measured density (ρ) and mass flow are in arbitrary units [a.u.].

⋅=

mHza.u.

500fdk

2.4 The Test Medium

The test plant could not be used with black coal for safety reasons. Therefore, glassspheres were used, with such properties as particle size, dielectric constant, andelectrostatic charging similar to pulverized coal.

Typically 85 % – 95 % by weight of pulverized coal particles downstream of the mill’sclassifier are smaller than 90 µm and 0.3 % or less are bigger than 225 µm. The twoglass particle sizes of 66 µm and 225 µm used for this test represent the mainfraction and the biggest possible size fraction of particles in coal pipes.

The manufacturer of the glass beads specifies a glass density of 158.6 lb/ft³ and an εr

of 2.28 at visible light. The εr may be slightly different for microwaves due todispersion.

The dielectric properties of milled coal and the glass spheres were tested in amicrowave resonator chamber. It was found that the frequency shift in thismeasurement was dependent upon the dielectric properties on the bulk density of thepulverized medium. By calculating the frequency shift per mass, the influence of thesphere packing were eliminated. The results are displayed in Table 2.1.

MediumBulk density

[lbs/ft³]Frequency shift/mass [MHz/lb]

Glass spheres 88.1 124.1Black coal (Primero) 35.8 200.1Black coal (Blumenthal) 35.8 193.9Black coal (Knurrow) 41.8 193.5

Table 2.1: Bulk density and frequency shift for fixed-bed powderof pulverized black coal and glass particles

The frequency shift at the same mass flow caused by glass is about 2/3 of the testedcoal. Therefore, the expected frequency shift for the mass flow measurement willonly be about 1/3 less for glass than for coal with the same mass. This ensures agood comparability between the test data obtained with glass particles used as thetest medium versus that which would have been obtained had coal been able to beused for the test medium.

The density for raw coal is between 78.0 and 81.8 lbs/ft³. Taking this density intoaccount, glass particles of the same size are about two times heavier than coal

particles. The weight differential plus the shape of the particles, spherical for glassand polyhedral for coal, give glass aerodynamic properties which result in a greatervelocity differential or slip between the airflow and the glass particles.

The electrostatic charging depends on particle collisions and particle conductivity.The velocity measurement needs a certain amount of electrostatic charge tocorrelate the sensor signals into a reliable time of flight measurement. Chargingsignal strengths for both size glass beads and bead mixtures were sufficiently high toobtain accurate time of flight measurements. Induced by the substantially greaternumber of particle amount within the airflow, the signal strength of 66 µm particleswas about five times higher than for the 225 µm particles.

Gravimetric Particle Size Distribution

00.2

0.40.6

0.81

1.21.41.6

0 50 100 150 200 250 300Particle size [µm]

Rel

. par

ticle

dis

tribu

tion

[%]

Fig. 2.4: Particle distribution as a function of particle size for the50/50 mix of 66 µm and 225 µm particles

Beside the pure 66 µm and 225 µm particles, a 50/50 mix by weight was also tested.Figure 2.4 shows the gravimetric distribution of particle sizes.

2.5 Feeder Calibration

To calibrate the feeder, glass beads were fed by the frequency controlled feeder intoa container for 30 seconds and their mass was weighed. This procedure wasrepeated twice for each particle size in steps of 50 rpm from 0 to 350 rpm. Theaverage of both sets of measurements was used for the feeder calibration.

The repeatability of the feeder calibration was then tested by 10 individualmeasurements with the 66 µm particles at 150 rpm. They were all in the range of±0.9 % by weight.

This was acceptable since the aim of the tests was not to examine the characteristicsof the screw feeder. And with all four sensor locations measuring physically the sameairflow/particle mixture, any scattering of the feeder is eliminated as a commonvariable.

Feeder Calibration

0

.11

.22

.33

.44

.55

0 50 100 150 200 250 300 350 400

Feeder speed [rpm]

Mas

s flo

w [l

bs/s

]

66 – 225 µmmix225 µm

66 µm

Fig. 2.5: Mass flow versus feeder speed for different particle fractions

The mass flow of the feeder is shown in Figure 2.5 for the specific particle fractions.The mass flow at a particular feeder speed depends on the particle size distribution.The mix of the two size fractions has the tightest packing and thus shows the highestmass flow. The 66 µm and 225 µm particles have different mass flows since forparticles <100 µm, adhesion forces influence the flowability within the screw feeder.

3. Testing Procedure

The test runs have been made under the aspect of realistic airflow velocities andparticle concentrations.

Within the capacity of the fan, three velocity levels were chosen at 72 ft/s, 82 ft/s, and92 ft/s, representing normal transport velocities in utility plants. With constant airvelocities the feeder speed was varied between 0 - 300 rpm in steps of 50 rpm.

Particle Concentration Range

0

0.006

0.013

0.019

0.025

0.031

0.037

0.044

0.050

0 50 100 150 200 250 300 350

Feeder speed [rpm]

Con

cent

ratio

n [lb

s/ft³

]

Fig. 3.1: Range of pf-concentrations based on feeder mass flow andtransport air flow

The pf concentrations in utility plants usually range between 0.012 to 0.031 lbs/ft³.Figure 3.1 shows the range of the expected pf concentration based on the ratio offeeder mass flow and the airflow during the tests.

Table 3.1 gives an overview of the different test runs: From the total number of 15test runs there were six runs with the 66 µm particles, six runs with the particle mixand three runs with the 225 µm particles.

Particle Size Test Numbers66 µm I,VI II,V III,IV225 µm I II III66 - 225 µm mix I,IV II,V III, VI

72 ft/s 82 ft/s 92 ft/sGas Velocity

Table 3.1: Test run number for each particle size

The following diagrams illustrate the data acquired for all test runs: DiagramFigures 3.2 and 3.3 show density and velocity measurement, and Figure 3.4 showsthe resulting mass flow of the 66 – 225 µm particles of Test Number V. Each feederstep was kept constant for at least 15 minutes to get about 20 individualmeasurements. From the last 15 measurements of each feeder step the average wastaken and plotted against the feeder mass flow in Figure 3.5.

0

6

12

18

24

30

36

42

48

54

61

13:0413

:1213:20

13:29

13:3713

:4613

:5414

:0214

:1114

:1914

:2814

:3614

:4414

:5315:0

115

:1015:1

8

0

50

100

150

200

250

300

350

400

CH 0

CH 1

CH 2

CH 3

feeder

Densities 66 - 225 µm, Test V

Den

sity

[a.u

./ft]

Feed

er s

peed

[rpm

]

Fig. 3.2: Density measurement Fig. 3.3: Velocity measurement

0

500

1000

1500

2000

2500

3000

3500

4000

4500

13:0413:11

13:1913

:2613:3

413:41

13:4913:57

14:04

14:1214:19

14:2714

:3414:4

214:49

14:5715:05

15:12

15:20

0

50

100

150

200

250

300

350

CH 0

CH 1

CH 2

CH 3

feeder

Mas

s flo

w [a

.u./s

]

Mass Flows 66 - 225 µm, Test V

Feed

er s

peed

[rpm

]

Fig. 3.4: Resulting mass flow and feeder signal Fig. 3.5: Mass flow of feeder versus Pf-FLO

0

16

33

49

66

82

98

13:04

13:11

13:1

913:2

613:

3413:4

113:4

913:

5714:0

414:1

214

:19

14:27

14:34

14:4

214:4

914:

5715:0

515:1

215

:20

CH 0

CH 1

CH 2

CH 3

Velocities 66 - 225 µm, Test VVe

loci

ty [f

t/s]

Mass Flow of Feeder vs.Pf-FLO, 66 - 225 µm, Test I - VI

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 198 397 595 793 992 1190 1389 1587

CH 0

CH 1

CH 2

CH 3

Pf-F

LO M

ass

flow

[a.

u./s

]

Feeder mass flow [lbs/hr]

All test runs have been plotted as displayed in Figure 3.5. As there is only a constantfactor between [a.u./s] and [g/s], a unified y-axis scaling was used to help evaluatethe influence of different particle sizes (see also Figure 4.8).

4. Results

4.1 Pf-FLO Measurement Accuracy

Figures 4.1 and 4.2 illustrate results only for the 50/50 particle mix. Results for otherparticle fractions are listed in the tabulations in Sections 4.1.1 and 4.1.2.

Mass Flow of Feeder versus Pf-FLO; 66 - 225 µm, Test I - VI

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 198 397 595 793 992 1190 1389 1587


P

f-FLO

mas

s flo

w [a

.u/s

]

Channel 0

Channel 1Channel 2

Channel 3

lin average

Standard deviation [a.u./s]: 158

Fig. 4.1: Evaluation of all test runs with 66 / 225 µm particles

The diagram in Figure 4.1 shows the evaluated results for all measuring channelsversus the feeder mass flow. The mass flow signals of all channels were averagedfor each feeder step and one particle fraction, and a linear coefficient was determinedfor it. With this coefficient the linear average was calculated as it can be seen in thediagram, indicated with “lin. average”. Based on the linear average the standarddeviation was determined for each measuring channel as listed in Table 4.1.

The repeatability of one channel for all tests and one particle size is exemplarilydisplayed in Figure 4.2. For other measuring channels and particle fractions, seetabulations in Section 4.1.2.

Repeatability of Channel 0; 66 – 225 µm Particles, All Tests

0

500

100

1500

2000

2500

3000

3500

4000

4500

0 397 793 1190 1587


P

f-FLO

mas

s flo

w [

a.u.

/s]

Test No. I 72 ft/s Test No. II 82 ft/s Test No. III 92 ft/s Test No. IV 72 ft/s Test No. V 82 ft/s Test No. VI 92 ft/s

(Standard Deviation: 3.3 %)

Fig. 4.2: Repeatability of channel 0 for 66 - 225 µm particles

4.1.1 Absolute Deviation

The standard deviation of one particle fraction from the linear average of all channelsis listed in Table 4.1. The errors in % refer to the maximum mass flow determined at300 rpm feeder speed.

Particle Size Channel Test No.

Number of

Measurements

Standard

Deviation

[a.u./s]

Max. Mass

Flow

[a.u./s]

Mean

Error

%

66 µm CH0 - CH3 Test I - VI 144 109 2462 4.4%225 µm CH0 - CH3 Test I - III 72 132 3520 3.8%

66 - 225 µm CH0 - CH3 Test I - VI 144 158 4000 3.9%

Table 4.1: Standard deviation and mean error for individual particle fractions

4.1.2 Repeatability

The relative deviation of one channel in all tests shows its repeatability. This includesthe scattering of the feeder but excludes systematic deviations from one channel incomparison to the others. Results for each channel are listed in the Tables 4.2 to 4.4.

Standard Deviation

To Linear

Average

Channel Test No.

Number of

Measurements [a.u./s]

Mean

Error

%

CH 0 Test I - VI 36 75.1 3.1%CH 1 Test I - VI 36 92.5 3.8%CH 2 Test I - VI 36 93.4 3.8%CH 3 Test I - VI 36 72.9 3.0%

The error in % refers to the maximum mass flow at 300 rpm: 2462 [a.u./s]

Table 4.2: Standard deviation of the individual channels with 66 µm particles

Standard Deviation

To Linear

Average

Channel Test No.

Number of


Mean

Error

%

CH 0 Test I - III 18 132.3 3.8%CH 1 Test I - III 18 65.0 1.8%CH 2 Test I - III 18 151.9 4.3%CH 3 Test I - III 18 111.7 3.2%


Table 4.3: Standard deviation of the individual channels with 225 µm particles

Standard Deviation

To Linear

Average

Channel Test No.

Number of


Mean

Error

%

CH 0 Test I - VI 36 131.7 3.3%CH 1 Test I - VI 36 114.1 2.9%CH 2 Test I - VI 36 163.9 4.1%CH 3 Test I - VI 36 141.2 3.5%


Table 4.4: Standard deviation of the individual channels with 66-225 µm particle mix

4.2 Influence of the Particle Size

Another purpose of the tests was to quantify the influence of particle sizes. As the225 µm particles can only be found in smaller percentages in pulverized coal, it is apractical fraction to resolve particle size dependent influences on density and velocitymeasurement. The transferability of the results to the operating condition of coal firedpower plants have to be viewed in relation to the real particle size distributions in coalpipes. In Section 4.2.3 the results out of the tests are evaluated.

4.2.1 Velocity Measurement

Measured Particle Velocities at Channel 0

0

16

33

49

66

82

98

72 ft/s gas velocity 82 ft/s gas velocity 92 ft/s gas velocity

Par

ticle

vel

ocity

[ft/s

]

225µm 66µm 66-225 µm mix

Fig. 4.3 Averaged particle velocities at channel 0

The measurements with 225 µm particles showed a difference of about 16.4 ft/sbetween airflow and particle velocity. This is due to the change in the aerodynamicproperties which increase the slip between particles and gas. The weight of particleschanges proportional to D³ but the cross section only changes proportional to D².

The velocity of the 66 µm particles, as well as the 50/50 mix, was found to be veryclose to the airflow velocity. The reason can be found by comparing the electrostaticsignal strength. The electrostatic signal strength of the 225 µm particles was found tobe significantly lower than for 66 µm. But the particle number increases with therelation of particle diameters to the power of three (see above). With a 50/50 particlemixture by weight, the number of 66 µm particles is about 28 times greater than forthe 225 µm particles. The cross correlation method resolves the time shift of thesensor signals by comparing their highest identity. If the signal strength of two time

shifts is of the same order, it might be possible to distinguish between the twovelocities. In case of the particle mix the signal strength of the 225 µm particles wasbelow the noise signal level of the 66 µm particles. Therefore, it is obvious that onlythe velocity of the 66 µm particles has been measured. The error in relation to therealistic particle size distribution is estimated in Section 4.2.3.

Velocities of the 225 µm Particles

0

16

33

49

66

82

98

72 ft/s gas velocity 82 ft/s gas velocity 92 ft/s gas velocity

velo

city

[ft/s

]

CH0 CH1 CH2 CH3

Fig. 4.4: Acceleration along the test duct of the 225 µm particles

In the tests which measured 225 µm particles only, channel 3 was found to havehigher velocities than the other channels. This can be explained by the position ofthis sensor pair located at the end of the horizontal test duct with the longest straightrun after a bend (see Figure 2.1). This leads to a certain acceleration, especially forthe bigger sized particles.

Influence of Mass Flow on Velocity of the Particle Mix

67

72

79

85

92

98

0 397 793 1190 1587

Feeder [lbs/hr]

velo

city

[ft/s

]

CH 0

CH 1

CH 2

CH 3

Fig. 4.5: Influence of the mass flow on the velocity of the particle mix in Test IV-VI

Figure 4.5 shows the influence of the mass flow on particle velocity. This effect, hereillustrated for the particle mix, is obvious when the averaged velocity of each feederstep is plotted over the mass flow as it is done in Figure 4.5. Each bundle of the fourchannels represents one step of the airflow velocity.

The higher the airflow velocity the higher the influence from pf load in the pipe.Channel 2 with the shortest distance from a bend seems to be affected most. It isassumed that this effect is related to particle interaction between 66 µm and 225 µmparticles, the latter having significantly lower velocities.

4.2.2 Density Measurement

Densities 66 µm Particles, Test V

0

6.1

18.3

24.4

30.5

36.6

42.7

13:32

13:41

13:50

13:58

14:07

14:16

14:25

14:34

14:42

14:51

15:00

15:09

15:18

15:27

15:36

15:45

15:54

0

50

100

150

200

250

300

350

400

CH 0

CH 1

CH 2

CH 3

feeder

Den

sity

[a.u

./ft]

Fee

der

spe

ed [

rpm

]

Fig. 4.6: Density measurement with 66 µm particles Test V.

Densities 225 µm Particles, Test I

0

15.2

30.5

45.7

61.0

76.2

10:14

10:20

10:27

10:3

310

:4010:4

610

:5310

:5911

:0611

:1211

:1911

:2511

:3211:3

811

:4511

:5111

:5812

:0412

:1112

:170

50

100

150

200

250

300

350

400

CH 0

CH 1

CH 2

CH 3

feeder

Den

sity

[a.

u./ft

]

Feed

er s

pee

d [r

pm

]

Fig. 4.7: Density measurement with 225 µm particles Test I

The diagrams in Figures 4.6 and 4.7 show the particle size dependent scattering ofthe densities in two test runs. The more extended scattering of the density signal for66 µm particles also increases with the load or particle numbers. With the 225 µmparticles there was less scattering although the densities in Figure 4.7 were nearlytwice as high. The fluctuation quantity for the particle mix is higher than the one forthe 225 µm, but less than the one for the 66 µm particles and was also influenced bythe load (see Figure 3.4).

The scattering of measurement is proved to be realistic and relates to the densityfluctuations of the particle flow. The different behavior can be explained with themean free path between particle collisions. The 66 µm particles have less particle-wall collisions but more particle-particle collisions in a smaller volume. Local highand low density concentrations do not average out within the pipe volume that hasbeen measured.

4.2.3 Mass flow measurement

Influence of the Particle Size

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 198 397 595 793 992 1190 1389 1587 Feeder mass flow [lb/hr]

Pf-F

LO m

ass

flow

[a.

u./s

]

lin average 66 µm lin average 200 µm lin average 66 - 200 µm

2.885

2.734

2.356

Ratio ([a.u.] to [lbs]):

Fig. 4.8: Influence of the particle size on the Pf-FLO measurement

The diagram in Fig. 4.8 shows the ratio of arbitrary units [a.u./sec] to mass [g] takenfrom the linear averages of the four measurement channels. This factor was found tobe a function of the used particle fraction. The temporarily applied ‘arbitrary units’ to‘frequency factor’ of 500 (see section 2.3) has to be divided by this ratio to get thecalibrated mass flow signal for each particle fraction. The resulting kfd is displayed inTable 4.5.

Particle Fraction ratio [a.u./lbs] kfd [g/m kHz]66 µm particles 2.3562 26.7225 µm particles 2.7342 23.066-225 µm particle mix 2.8854 21.8

Table 4.5: Ratio of arbitrary units to mass and the resultingmass frequency factor kfd for each particle fraction

The deviation of 13.8 % between the 66 and 225 µm particles can be regarded asdependent on particle size. The deviation of the 66 – 225 µm particle mix is due tothe deviation of the velocity measurement described in Section 4.2.1.

The results have to be compared with the real particle size distribution in a coal pipeafter classifier. These deviations have influence only on the absolute accuracy butnot on the relative accuracy between several pipes of one mill since a segregation ofparticle fractions between several pipes is not probable.

The following calculations are linear estimations of the error in real particle sizedistributions within the results of the tests: For an examplary particle distribution of15% >90 µm and 0.2 % >225 µm it was assumed to have a discrete mixture out of84.8 % 66 µm particles, 15 % 145 µm particles and 0.2 % 225 µm particles. Therelation of the diameters was taken to interpolate the velocity of the 145 µm particleslinear between the velocities of the 66 µm and 225 µm particles. Also the relation ofthe diameters was taken to interpolate the deviation of density measurement for145 µm particles linear between the densities of the 66 and 225 µm particles.

Deviation caused by Particle Size

0

20

40

60

80

100

120

100% 66 µm 89.9% 66µm10.0% 145µm0.1% 225µm

84.8% 66µm15.0% 145µm0.2% 225µm

79.0% 66µm20.0% 145µm1.0% 225µm

Rel

ativ

e m

ass

flow

[%

]

225 µm

145 µm

66 µm

100.0 101.2 101.8 102.5

Fig. 4.9: Estimated deviation by modeled particle size distribution

The results of the estimation are shown in Figure 4.9. If the distribution changes fromcolumn 2 to 3, the estimated error is about 0.6 % of the mass flow. The distribution ofthe last column shows a 2.5 % error but this change in particle distribution is meantto be quite unrealistic in an optimized milling process and will also influence thecombustion badly.

5. Abstract

A reference test at the pneumatic conveying test plant of the “Lehrstuhl fürMechanische Verfahrenstechnik” at the University of Halle- Wittenberg wasestablished to prove the accuracy of a flow measurement system for air-solid flows.The test facility consists of a calibrated screw feeder, a pipe system with vertical andhorizontal elements, and the particle separation equipment. Glass beads were usedas a test medium whose physical properties are comparable to coal dust if taking intoaccount the measurement principle. In addition to the single sized test materials withdiameters of 66 µm and 225 µm, a 50/50 mixture by weight of both particle sizes wasused. The experimental matrix for the tests covered the usual operational range forthe throughput and the velocity in coal pipes of power plants.

In total, four measurement instruments were located at two locations in the upwardrun and two locations in the horizontal run of the test pipe. From the measureddensity and velocity signals of the particles the mass flow was calculated in eachcase and compared with the calibrated feeder signal. The measuring error wasrelated to a single standard deviation.

As a result, the measured deviation from the feeder signal is < 4.5 %; this applies tothe entirety of all four measuring points and all particle fractions. For individualsensors the deviation lies in the range between 1.8 % to 4.3 %, and is in this casenot significantly dependent on the used particle size.

In addition, investigations of the influence of the particle size were carried out. Withinthe wide range of the used particle fractions, the density and velocity measurementshowed some size dependencies. However, the measured differences have only littleinfluence on the accuracy (< 0.6 %) since in utility plants the grading of coal dustusually changes only in a comparable small range.

IBAMTM

Individual Burner Airflow Measurement



IBAM

Performance Benefits

combination of fixed and/or adjustable inlet sleeve/diskdampers, and in most installations the burners are equippedwith actuators to facilitate DCS controlled modulation of burnerSA airflow corresponding to varying fuel loads. Unfortunatelysome low NOx burners come equipped with a non-calibratedairflow sensing device and most others lack any means todetermine how much SA is entering the burner, resulting inthe need for extensive burner tuning targeted at meeting themanufacturer’s NOx and CO emissions guarantees but notrepeatable or maintainable long term over varying loadconditions.

Just as there are variances in fuel distribution to each burner,multiple burners served by a common or partitioned wind boxcan have substantial burner-to-burner imbalances in SA.Accurate and repeatable measurement of individual burnerSA requires Air Monitor Power’s IBAMs, airflow probes thatare economically feasible to retrofit into existing burners andyet able to accommodate a variety of design challenges –the absence of any undisturbed cross section of airflowpassage; an installation location typically downstream of amodulating inlet sleeve, disk or damper; a broad range ofboiler operating conditions; the presence of fly ash particulateand 1200ºF operating temperatures; and for wall fired burnersthe broad range of airflow pitch and yaw vectors produced bythe adjustable swirl angle blades.

The Need for Burner Airflow Measurement

The objectives in the power industry today are twofold; tolower emissions, and increase plant performance. Precisemeasurement of combustion airflow and fuel rates positivelycontributes to achieving those objectives by providing theinformation needed to optimize burner stoichiometric ratiosand facilitate more complete, stable combustion. As indicatedby the following chart, optimization of the key combustionparameters of NOx, O2, LOI, CO, and boiler efficiency onlyoccurs within a narrow range of air-to-fuel ratios.

Traditional coal fired power plants lacked any means tomeasure and control airflow into individual burners. Newburner designs prompted by Clean Air Act attainment levelsfor NOx reduction are typically comprised of inner and outerairflow barrels to introduce secondary air (SA) to the flameball, adjustable swirl angles blades in each barrel, a

O2

• Provides burner-to-burner relative secondary airmeasurement to within 5% accuracy.

• Facilitates control of individual burner stoichiometry andair-to-fuel ratio.

• Increases the manageable range of burner turndown.

• Reduces unburned carbon in flyash.

• Permits burner-to-burner balancing of secondary airflow,intentional burner airflow biasing, or burner plus OFAcombustion staging.

CO

NOx

• Reduces CO and the potential for corrosion in the lowerfurnace.

• Reduces NOx through furnace operation with less excessair.

• Reduces burner throat slagging.

• Safely reduces excess O2.

Substantial reductions in NOx levels are obtained when theIBAM’s accurate SA measurement is integrated into DCS burnercontrol to dynamically maintain burner-to-burner airflow balanceor a bias strategy corresponding to the varying fuel loads. Theaddition of a Pf-FLO System for coal flow measurement permitscontrol of SA to achieve individual burner stoichiometryobjectives, safely lowering overall NOx and excess O2 whilesimultaneously reducing areas of high CO that otherwise produceundesirable slagging and water wall corrosion.

Op

tim

um

Zo

ne

Co

mfo

rtZ

on

e


Individual Burner Airflow Measurement

Design & Testing

Air Monitor Power IBAMs have been applied to virtually everyOEM and after-market burner design; each one customengineered to reflect the user's unique burner or OFA port,and windbox configurtaion. Based upon the Fechheimer-Pitotmeasurement technology, the IBAM design process drawsfrom a broad array of construction options: Quantity andpattern of individual total pressure (TP) and static pressure(SP) sensing holes, CW and/or CCW rotation of the individualTP and SP sensing probes; rotation of the entire IBAMassembly, special high temperature materials and abrasionresistant Tungsten Carbide coatings. Wind box configurationand burner symmetry guide the quantity of IBAMs needed toobtain desired accuracy and repeatability.

Each IBAM design is extensively tested and characterized inAir Monitor Power’s large scale test duct using a full sizemock up of the wall fired burner or corner fired control damper,with testing conducted over a broad matrix of customerspecific sleeve damper or inlet disk positions, swirl anglesettings, and boiler operating conditions. The result is a multi-order polynomial equation, with one or two variables, toaccurately correlate the TP and SP signals from the IBAMsplus damper or disk position into mass flow with an accuracyof ±5%.

CAMS

The Air Monitor Power CAMSTM – Combustion AirflowManagement System is designed to fulfill the need for areliable and accurate means of f low measurement incombustion airflow applications.

Combined into a single engineered package are the CAMMTM

– Combustion Airflow Management Module containing themicroprocessor based instrumentation to measure the airflowand manage the purge cycle, and AUTO-purge to protectagainst any degradation in performance of the duct mountedmeasurement device(s) due to the presence of airborneparticulate.

IBAM ProbeFor Wall Fired Applications

• Offset Fechheimer static pressure sensors.• Chamfered total pressure sensors.• All welded Type 316 stainless steel.• Optional Inconel, 310SS, and Tungsten Carbide coated.

IBAM SAP/TFAFor Corner Fired Applications

• Type 316 stainless steel pressure sensing chamber.• Reverse Fechheimer pressure sensing ports.• Bolted construction permits disassembly for long-term

maintenance.

Test Duct Windbox with Burner Mock-up

125-510 (04-09)



CEMSTM – Continuous Emissions Monitoring SystemAir Monitor Power's CEMSTM – Continuous Emissions Monitoring Systems assist incomplying with the Clean Air Act’s stringent emission measurement standards andthe requirements of 40 CFR 75. Air Monitor has assembled a cost effective integratedsystem consisting of in-stack flow measurement equipment and companioninstrumentation to provide continuous, accurate, and reliable volumetric airflowmonitoring of stacks and ducts of any size and configuration.

CATM – Combustion Airflow Measuring Station & VOLU-probe/SSTM

Traverse Probes. Air Monitor Power's duct mounted airflow measurement deviceshave been designed to accurately and repeatedly measure air mass flow in powerplants. The Combustion Air (CA) StationTM includes honeycomb air straightener toaccurately measure in shorter straight duct runs than any other flow measurementdevice. The VOLU-probe/SSTM delivers accurate airflow measurement performancein the form of an insertion probe. Both devices feature Type 316 stainless steel flowsensing arrays.

Engineering & Testing Services. Air Monitor Power offers complete engineering and testing to analyze air andcoal delivery systems. Air Monitor Power’s field testing services use 3D airflow traversing and Pf-FLO coal flowmeasurement systems for the highest possible accuracy. To ensure cost effective and accurate solutions, Air MonitorPower has full scale physical flow modeling capability and in house Computational Fluid Dynamics (CFD). CFD analysisis used to analyze flow profiles and design/redesign ductwork to improve overall performance. Full scale model fabricationand certified wind tunnel testing is used to develop application specific products that will measure accurately where nostandard flow measurement can.

Pf-FLOTM – Pulverized Fuel Flow ManagementThe Pf-FLOTM system performs continuous and accurate fuel flow measurement inpulverized coal fired combustion applications, providing boiler operators with the real-time data needed to balance coal mass distribution between burners. Balanced fuelimproves combustion efficiency and lowers emissions while reducing in-furnaceslagging, coal layout, fuel slagging, and coal pipe fires.

VOLU-probe/SSTM Stainless Steel Airflow Traverse Probes.Multi-point, self-averaging, Pitot-Fechheimer airflow traverse probes with integralairflow direction correcting design. Constructed of Type 316 stainless steel andavailable in externally and internally mounted versions for harsh, corrosive or hightemperature applications such as fume hood, laboratory exhaust, pharmaceutical,and clean room production and dirty industrial process applications.


AAAA DDDDBBBB RRRRIIII LLLLEEEEYYYY TTTTEEEECCCCHHHHNNNNIIIICCCCAAAALLLL PPPPUUUUBBBBLLLL IIIICCCCAAAATTTT IIIIOOOONNNN

Post Office Box 15040Worcester, MA 01615-0040

http://www.dbriley.com

Post Office Box 15040Worcester, MA 01615-0040

http://www.dbriley.com

RST-153

ACCURATE BURNER AIR FLOW MEASUREMENT FOR LOW NOx BURNERS

by

Dave EarleyAMC Power

andCraig Penterson

DB Riley, Inc.

Presented at theEighth International Joint ISA POWID/EPRIControls and Instrumentation Conference

June 15-17, 1998Scottsdale, Arizona

© DB Riley, Inc. 1998

ACCURATE BURNER AIR FLOWMEASUREMENT FOR LOW NOx BURNERS

byDave EarleyAMC Power

andCraig Penterson

DB Riley, Inc.

ABSTRACT

In 1990, Congress enacted an amendment to the Clean Air Act that required reductions inNOx emissions through the application of low NOx burner systems on fossil fueled utilitysteam generators. For most of the existing steam generator population, the original burningequipment incorporated highly turbulent burners that created significant in-furnace flameinteraction. Thus, the measurement and control of air flow to the individual burners wasmuch less critical than in recent years with low NOx combustion systems. With low NOx sys-tems, the reduction of NOx emissions, as well as minimizing flyash unburned carbon levels,is very much dependent on the ability to control the relative ratios of air and fuel on a per-burner basis and their rate of mixing, particularly in the near burner zones.

AMC Power (AMC) and DB Riley, Inc. (DBR), and a large Midwestern electric utility havesuccessfully developed and applied AMC’s equipment to low NOx coal burners in order to enhance NOx control combustion systems. The results have improved burner optimization and provided real time continuous air flow balancing capability and the control of individual burnerstoichiometries.

To date, these enhancements have been applied to wall-fired low NOx systems for balanc-ing individual burner air flows in a common windbox and to staged combustion systems.Most recently, calibration testing in a wind tunnel facility of AMC’s individual burner airmeasurement (IBAM™) probes installed in DB Riley’s low NOx CCV® burners has demon-strated the ability to produce reproducible and consistent air flow measurement accurate towithin 5%.

This paper will summarize this product development and quantify the benefits of itsapplication to low NOx combustion systems.

2

INTRODUCTION

In an effort to provide greater control of combustion air flow and subsequent burnerstoichiometry on multiple low NOx burner installations, DB Riley and AMC Power,in cooperation with a large Midwestern electric utility company, have developed a uniqueprobe for accurately measuring burner air flow. These probes, referred to as individual burn-er air measurement (IBAM™) probes, are currently used in all DB Riley low NOx burners.The benefits of better air flow control in low NOx burner installations is the ability to oper-ate at lower NOx levels and/or lower unburned carbon levels in the flyash.

This paper focuses on the development, application and benefits of the IBAM™ probesspecifically in DB Riley low NOx CCV® coal burners. The paper also discusses the benefitsof accurately measuring combustion air flow in other low NOx systems such as overfire air(OFA), secondary air in cyclones, and primary air in pulverizer systems.

REVIEW OF CCV® BURNER TECHNOLOGY

DB Riley has been using CCV® burners for reducing NOx emissions from pulverized coalfired utility boilers for many years. With over 1500 low NOx coal burners being supplied tothe utility industry since 1990, the CCV® technology has developed into a “family” of lowNOx burners including the CCV® single register, dual air zone and cell burner designs.This wide range of designs allows the flexibility to select a design most suitable for a par-ticular application, based on NOx reduction requirements, boiler configuration, and budgetconstraints.

Figure 1 shows schematic drawings of the three low NOx coal burner designs. Commonto these designs is a unique patented venturi coal nozzle technology (U.S. Patent No.4,479,442) which was developed in the early 1980’s for reducing NOx emissions on coal firedutility boilers. The venturi nozzle, low swirl coal spreader and secondary air diverter in allof these designs produce a fuel rich flame core, the fundamental conditions necessary forminimizing the formation of both fuel and thermal NOx2.

The combustion air side of the CCV® burner design is similar for single register and cellburner applications. Secondary air initially passes through the air register, which impartsswirl, and then through the burner barrel and over the secondary air diverter. Secondaryair is diverted away from the primary combustion zone which reinforces the fuel rich flamecore produced by the venturi nozzle for further control of NOx emissions.

As shown in the schematic, the air flow measurement devices or IBAM™ probes are radi-ally inserted into the burner barrel for measuring secondary air flow on an individual burn-er basis. As discussed later in this paper, the probes were uniquely designed and strategi-cally located to provide accurate measurement of air flow in this highly turbulent, swirling,non uniform flow field produced by the air register of single register and cell burner designs.

The air register used on the CCV® dual air zone burner design contains axial swirl vanesinstalled in both the secondary and tertiary air passages of the burner. The IBAM™ probesfor this design are positioned immediately upstream of the axial swirl vanes where the flowfield is more uniform, axial, and non-swirling. Accurate measurement of both secondary andtertiary air flow on a per-burner basis is important to establish the proper flow split for min-imizing NOx in this burner design.

3

Figure 1 DB Riley Low-NOx CCV® Burners

CCV® Single Register Burner CCV® Cell Burner

CCV® Dual Air Zone Burner

REVIEW OF AMC POWER FLOW MEASUREMENT TECHNOLOGY

The flow measurement technology used in DB Riley CCV® burners is based upon AMCPower’s VOLU-probe® design (U. S. Patent 4,559,835). The VOLU-probe® is a multiplepoint, self-averaging pitot tube requiring very little straight duct run to maintain an accu-rate flow signal.

The VOLU-probe® operates on the Fechheimer Pitot derivative of the multi-point, self-averaging pitot principle to measure the total and static pressure components of airflow.Total pressure sensing ports, with chamfered entrances to eliminate air directional effects,are located on the leading surface of the VOLU-probe® to sense the impact pressure (Pt) ofthe approaching airstream (Figure 2). Fechheimer static pressure sensing ports, positionedat designated angles offset from the flow normal vector, minimize the error-inducing effect

4

of directionalized, non-normal, airflow. As the flow direction veers from normal (Figure 3),one static sensor is exposed to a higher pressure (Ps + part of Pt) while the other is exposedto a lower pressure (Ps - part of Pt). For angular flow where a = ±30 degrees offset from nor-mal, these pressures are offsetting and the pressure sensed is true static pressure. It is thisunique design of offset static pressure and chamfered total pressure sensors that make theVOLU-probe® insensitive to approaching multi-directional, rotating airflow with yaw andpitch up to 30 degrees from normal, thereby assuring the accurate measurement of thesensed airflow rate without the presence of airflow straighteners upstream.

Figure 2 VOLU-probe® With Total Pressure Sensing Ports

Figure 3 VOLU-probe® with Static Pressure Sensing Ports

AMC Power then applied these VOLU-probes® to DB Riley’s CCV® burner designs.The resulting assembly was referred to as IBAM™ or individual burner air measurementprobes. A photograph of a typical IBAM™ probe assembly is shown in Figure 4. As shownin Figure 5, the multiple point sensors used in the IBAM™ probes also minimizes the errorcaused by flow stratification.

The Fechheimer pitot method of flow measurement in a burner allows for true axial flowmeasurement even when flow vectors are non-axial. This is where traditional flow measur-ing devices (static pressure comparisons, forward-reverse pitot tubes, piezometer rings, ther-

5

Figure 5 Burner Register Flow Stratification

Figure 4 Typical IBAM™ Probe Assembly for Burner Air Flow Measurement

mal anemometers and more) fall short. In fact, because many of these other devices cannotdistinguish axial flow from swirling flow, the use of them can actually lead to a user unbal-ancing previously balanced burners. That is, two (or more) burners may have the same trueaxial flow but because the flow vectors approach the flow measuring devices at varyingangles, the flows are interpreted as being different.

Thermal anemometers are not suitable for burner balancing because an RTD or resis-tance temperature detector in a flow stream cannot determine angular flow from axial flow.That is, thermal anemometers are calibrated for certain conditions and if these same condi-tions are not met, the calibration coefficients will be incorrect. If two anemometers for twodifferent burners are calibrated to the same flow condition (i.e. axial flow) and they have thesame axial flows but their angular orientations are different, they may read differently.

6

The result is that because burners lack straight duct run and because flow in burnersbecomes directionalized from flow obstructions such as swirl vanes and register vanes, tra-ditional flow-measuring devices have proven to be ineffective.

INTEGRATION AND TESTING OF AN IBAM™ PROBES IN DB RILEY CCV® BURNERS

Figure 6 shows the typical application of AMC Power’s IBAM™ probes to a CCV® singleregister burner barrel. Two stainless steel probe assemblies, with both total and static pres-sure tubes, are installed perpendicular to the burner barrel and connected by appropriatetubing to a local pressure gage mounted on the burner front or to a flow transmitter. Theprobes are uniquely designed and oriented for accurate measurement of secondary air flowin the swirling non-uniform flow field.

Sta

tic P

ress

ure

Tota

l Pre

ssu

re

TypicalProbe Assembly

Figure 6 Application of IBAM™ Probes to DB Riley CCV Single Register Burner

Testing of the probes in late 1995 on a 600 MW utility boiler equipped with DB RileyCCV® single register cell burners was performed to determine the number of probe assem-blies that would actually be required to produce a representative flow indication or mea-surement. Data were collected for 2, 3, and 4 probe assemblies. The results suggested that2 or 3 probe assemblies were sufficient provided the probes are carefully located to precludeany adverse effects of flow obstructions or disturbances caused by ignitors, scanner tubes,and nozzle support legs. The actual accuracy of the probe measurement could not be evalu-ated since only a small number of burners were equipped with the IBAM™ probes. However,the results were found to be very repeatable during subsequent tests several months later.

Testing of the IBAM™ probes in a 100 million Btu/hr (29 MW) CCV® dual air zone testburner at Riley Research was performed in mid-1995 to evaluate probe location in the burn-er barrel and probe angle or orientation with respect to the burner axis when installeddownstream of the axial swirl vanes in the secondary air annulus. The DB Riley Research

7

Combustion Test Facility, shown in Figure 7, can test a single full-scale coal burner for awide range of firing conditions3.

Results of locating one probe assembly at 0°, 120°, or 240° CCW from top dead centershowed no significant variation in the flow measurement. This indicated good peripheraldistribution of air within the secondary air annulus. However, the probe angle was sensitive

Figure 7 Aerial View of the Combustion Test Facility atDB Riley Research, Worcester, Massachusetts

to the swirl vane position in regard to accurate flow measurement. Various probe angleswere tested which resulted in an optimum angle that appeared to be the least sensitive toswirl vane angle or positioning. With the probe oriented and positioned at optimum settings,the error in the IBAM™ probe air flow measurement relative to the ASME venturi flow mea-surement was only +2%.

More recently, extensive testing was performed in AMC’s wind tunnel facility in SantaRosa to actually calibrate the IBAM™ probes installed in a CCV® single register low NOxburner manufactured for subsequent installation in a 260 MW Midwestern utility boiler.AMC’s wind tunnel facility is equipped with multiple ASME flow nozzles for precise air flowmeasurement. The purpose of the testing was to quantify the accuracy of the IBAM™ probes,confirm the optimum probe angle or orientation from previous field and laboratory testing,and to evaluate the axial positioning of the IBAM™ probes relative to the air register.

Figure 8 is a photograph of the CCV® burner installed in the AMC wind tunnel facility.The IBAM™ probes were at the 1:30 and 6:00 clock positions in the photograph. A Plexiglastube was used to simulate an oil ignitor while a cardboard sono tube was used to simulatethe coal nozzle.

As shown in Figure 9, the results indicated the variance or error in the IBAM™ flowmeasurement, when compared to the flow measured using the ASME nozzles typically var-ied from -1% to +13% for a wide range of burner settings (various register vane and shroud

8

Figure 8 IBAM™ Probe Calibration Testing in AMC’s Wind Tunnel Facility

Figure 9 IBAM™ Flow Variance for Various Shroud Position and Register Vane Settings

settings) tested. The error band was reduced to +5% to +10% for more “normal” burner set-tings. Typically, on multiple burner installations, register or swirl vanes are all set to thesame angle while only the burner shrouds are manipulated to various positions as necessaryto balance air flow burner to burner. So, for a given register setting of 25 the error bandreduces even more. The test results confirmed the probe angle or orientation selected fromprevious field and lab testing was still valid while the axial location of the probes relative tothe air register was also found to be important. The data was observed to be extremelyrepeatable.

Future test plans are to calibrate a CCV® single register low NOx cell burner equippedwith IBAM™ probes in AMC’s wind tunnel facility again for subsequent installation in a1300 MW utility boiler.

9

BENEFITS OF ACCURATE AIR FLOW MEASUREMENT

The benefits of having the ability to accurately measure individual burner air flow in amultiple burner windbox arrangement are significant. The following lists the most impor-tant benefits in low NOx combustion systems.

• Capability of balancing secondary air flow burner to burner• Capability to deliberately bias air flow burner to burner if desired• Improved control of NOx emissions and flyash UBC• Improved control of individual burner stoichiometry and air to fuel ratio• Improved control of burner throat slagging• Lower excess air operation for lower NOx• Greater burner turndown capability• Reduces the potential for lower furnace corrosion

In this regard, DB Riley has standardized on the use of AMC Power’s IBAM™ probes forall low NOx coal, oil, and gas burner applications.

The VOLU-probe® has also been successfully used in a variety of other combustion airflow applications. Pulverizer primary air flow measurement and control is an integral partof most low NOx projects. AMC Power has supplied the air flow probes for many of theseapplications, as shown in Figure 10.

Optimizing airflow to the mills has been important not only for helping to reduce NOx,but also for reducing LOI. Primary airflow can either be performed by measuring hot andtempering airflows independently or totalized, after they mix.

Figure 10 Primary Air Flow Measurement

10

In an effort to increase overall boiler efficiency, many plants are looking at ways to elim-inate pressure drop from their systems. In many installations, airfoils, venturis, and/ordams can be removed from ducts and replaced with VOLU-probes® (Figure 11), providingthe benefits of gaining extra FD fan capacity, gaining airflow, and improving the flow mea-surement, which can lead to control optimization.

DB Riley and AMC are currently working on a project to remove up to 10” w.c. of per-manent pressure drop from existing cyclones by removing existing airflow measuringdevices and replacing them with devices designed by AMC. This improvement will yieldmore needed airflow. It will also allow for the balancing of cyclones, helping NOx and main-tenance issues. Recently performed wind tunnel testing has shown that these new devices willallow for accurate cyclone airflow measurement as well as cyclone balancing to within 3%.

Overfire airflow is another application that has been successfully performed by DB Rileyand AMC as part of low NOx systems. Figure 12 shows an example of how VOLU-probes®are installed in a typical OFA duct on a low NOx system. Accurate measurement of OFA flowin each duct provides the ability to balance the flows to each port for better NOx and UBCperformance.

Figure 11 Secondary Air Flow Measurement

FlowMeasuringDevice

Figure 12OFA Air Flow Measurement

SUMMARY

AMC Power, DB Riley, and a large Midwestern electric utility have developedindividual burner air flow measurement probes for accurate measurement of combustion airflow in DB Riley low NOx CCV® burners. Results of extensive calibration testing in com-bustion test furnaces and wind tunnel facilities have yielded measurement accuracies towithin 5%. The major benefit of accurate burner air flow measurement is the ability to bal-ance burner air flow and stoichiometry in multiple burner common windbox applications,

CEM SYSTEMSContinuous Emissions Monitoring



40 CFR 75 Summary

On October 26, 1992, the Environmental Protection Agency (EPA)signed into law Part 75 of the Code of Federal Regulationsgoverning Continuous Emission Monitoring. First proposed inDecember 1991 and subjected to extensive public review, thefinalized version of 40 CFR 75 follows. The full version of 40CFR 75 outlines the purpose, standards, certification process,and recordkeeping requirements for monitoring seven emissionparameters:

SO2 concentration OpacityCO2 concentration Volumetric flowNOx concentration Diluent concentration (O2 or CO2)Moisture concentration

Volumetric Flow Monitoring Systems

Prior to receiving certification by the EPA, a flow monitoringsystem must satisfy continuous emission monitoring requirementsvia a detailed test procedure to verify that the performance andsystem configuration is within the EPA mandated requirementsrelative to:

Measurement LocationInterference CheckCalibration ErrorRelative AccuracyBias

U.S. EPA Requirements for Continuous Emissions Monitoring (CEM)

Bias is a systematic error resulting in measurements that will beconsistently low or high relative to the true flow measurement.Flow monitors that exhibit the need for low bias will not pass

certification. Flow monitors that exhibit the need for high biascan have the monitor output values adjusted by a singlecorrection factor.

Bias

Effective January 1, 2000 the accuracy requirement forvolumetric flow was lowered to 10%. Flow monitors achievinga relative accuracy of 7-1/2% were granted a reduction in RATAtesting frequency from semi-annually to annually.

Correct selection of probe location and quantity, combined withfield calibration prior to certification permits the Air Monitor flowmonitoring system to achieve annual RATA frequencies.

Relative Accuracy

EPA defines an appropriate location for installation of a CEMSystem by referencing 40 CFR 60, Appendix A, Method 2. Thedesired location would be one with a minimum of eight stack orduct diameters downstream and two diameters upstream ofany flow disturbance. Minimum siting requirements are two

downstream diameters and one-half upstream diameter of anyflow disturbances. Provisions are made in 40 CFR 75 to petitionthe EPA for an alternate monitoring location when the minimumsite requirements cannot be met.

Measurement Location

Regardless of the technology used to measure flow, all flowmonitoring systems must include a means to ensure the in-stackequipment remains free of obstructions that would affectongoing measurement accuracy. For differential pressure flow

monitors, the requirement is for an automatic timed, periodicback purge using compressed air to keep the probe sensingports clean and expel condensation of wet gases. Air Monitormeets this requirement with its AUTO-purge/CEM System.

Interference Check

Calibration error is calculated as the percentage differentialbetween a reference value and the actual monitorinstrumentation reading. Calibration error must be determinedduring the certification process, then dail y, and periodicallythereafter. The daily check of calibration must verify that theerror has not deviated more than 3.0 percent from the reference

value, with excessive deviation necessitating instrumentationrecalibration. Air Monitor's instrumentation, consisting of itsMASS-tron/CEM transmitter with AUTO-cal function, providesdaily reporting of calibration flow outputs for calculation ofcalibration error in the DAS.

Calibration Error

RATA FREQUENCY REQUIREMENTSFOR FLOW MONITORING SYSTEMS

Relative Accuracy

10.0%

7.5%

Semi-Annual

Annual

Required RATA Frequency

To assist in complying with the Clean Air Act's stringent emissionmeasurement standards, Air Monitor has assembled a costeffective integrated system consisting of in-stack flow

measurement equipment and companion instrumentation toprovide continuous, accurate, and reliable volumetric flowmonitoring for stacks and ducts of any size and configuration.

System Components

In-Stack Flow Traverse Probe(s)

Required is the means to accurately monitor the average flowrate and temperature of the stack emissions. Flow rate monitoringis performed by sensing individual flow components at multiplepoints (traversing) across one or more diameters for circularstacks or along multiple parallel traverses for rectangular stacks,and averaging the obtained values. Average temperaturemeasurement is achieved using one or more temperature probesto obtain a single full traverse of a stack.

The Air Monitor STACK-probe is an airflow traverse probe basedon differential pressure (Pitot-Fechheimer) technology formeasuring airflow; the same technology that will be used duringthe certification process to verify relative accuracy of the flowmonitoring system. Each STACK-probe consists of two separateround tube self-averaging manifolds; one to measure the stacktotal pressure, and the other to measure stack static pressure.Multiple Pitot-Fechheimer ports are positioned on each manifoldon an equal area basis (for rectangular stacks) or on an equalconcentric area (for circular stacks). Similarly, average stacktemperature is measured using a temperature probe withmultiple sensing elements spaced along the probe length.

The engineered truss type design of the STACK-probe utilizestubular structural materials welded to a 6", 150# raised face

pipe flange, permitting cantilever probe mounting in evenextremely large stacks. Standard Type 316 stainless steelconstruction ensures long-term durability and continuingaccuracy in most installations, with materials such as HastelloyC22 and Inconel available for extreme temperature and/orseverely corrosive applications.

As a basic instrument, the STACK-probe does not require anyinitial or periodic calibration to measure flow accurately. As apassive device with no moving parts or active electrical circuits,removal of the STACK-probe from the stack after installation forrepair or calibration is not required.

Probe Back Purge

Required for differential pressure flow monitoring systems is aback purging means to ensure that the in-stack flow monitorprobe has its pressure sensing ports and averaging manifoldmaintained free of particulate build-up and vapor condensation.

When activated by Air Monitor's MASS-tron/CEM or the DataAcquisition System (DAS), the AUTO-purge/CEM Systemsequentially operates a combination of failsafe valves toautomatically back purge the sensing lines and the S TACK-

probes with high volume/high pressure compressed air for ashort duration, while simultaneously isolating the transmitterfrom over-pressurization.

Standard AUTO-purge/CEM construction mounts all componentsin a steel NEMA 4 rated enclosure, with all wetted parts made ofcopper or brass. The AUTO-purge/CEM is optionally available ina stainless steel NEMA 4X enclosure, with stainless steel wettedparts for corrosive applications.

AUTO-purge/CEM MASS-tron/CEM

The Air Monitor MASS-tron/CEM multi-variable, ultra-lowdifferential pressure transmitter converts the temperature anddifferential pressure flow signals received from the in-stacktraverse probe(s) into a continuous output signal representingthe volumetric flow in SCFM (wet or dry basis) being dischargedinto the atmosphere.

To meet the calibration error reporting requirements of 40 CFR75, the MASS-tron/CEM used in stack flow monitoringapplications is equipped with AUTO-cal circuitry. Once every24 hours, the MASS-tron/CEM executes an AUTO-cal calibrationcycle, during which the transmitter output signal is held at thelast sensed flow level. Sequentially activated valves exposethe MASS-tron/CEM transmitter to reference pressures for zeroand span resulting in corresponding calibration flow outputs,after which the MASS-tron/CEM resumes normal flow monitoring.

In addition to the local display of information, the MASS-tron/CEM provides outputs to the Data Acquisition System (DAS) for:

Temperature ºF 4-20mADCAUTO-cal Acknowledgment Dry ContactAUTO-purge Acknowledgment Dry ContactSCFM 4-20mADC*Zero Calibration Error Signal 4-20mADC*Span Calibration Error Signal 4-20mADC*

*Serial Output. See Figure below.

The MASS-tron/CEM is available in either a 19" rack mount or aNEMA 4 enclosure, with a NEMA 4X stainless steel enclosureoptionally available.

Data Reporting

Data Reporting & Installation Requirements

T0 T1 T2 T3 T4

T0 MASS-tron/CEM internal timer or external dry contact from DAS initiates AUTO-cal cycle. Transmitter output signal for stack flow isheld at the last flow value during the AUTO-cal cycle.

T1 AUTO-cal relay contact closes. Zero flow output signal begins. T2 AUTO-cal relay contact opens. Flow output signal goes to 4mADC. T3 AUTO-cal relay contact closes. Calibration flow output signal begins. T4 AUTO-cal relay contact opens. Calibration flow output signal ends. Transmitter returns to reporting actual stack flo w.

Purge Air Requirement. 80 to 125 psig at 100 CFM, oil and dirtfree. 1 to 24 purge cycles per day, with a duration of less than 2minutes during which compressed air is released.

Instrument Air Requirement. 25 to 120 psig instrument airsupply. Per ISA S7.3, required for AUTO-span equipped MASS-tron/CEM.

Ambient Temperature. 32ºF to 140ºF for the AUTO-purge/CEM panel; 60ºF to 80ºF for the MASS-tron/CEM. Recommendedinstallation is within the environmentally controlled analyzerinstrumentation shelter.

Accumulator Tank (strongly recommended) . Requirescoalescing filter, pressure regulator, and check valve at the tankinlet.

1 stack traverse – 80 gallons2 stack traverses – 120 gallons

Electrical Power Requirements. 120VAC, 10 amp for heaterequipped AUTO-purge/CEM panel; 120VAC, 1 amp for MASS-tron/CEM.

Line from Accumulator Tank to AUTO-purge/CEM Panel.25' maximum length, 1/2" pipe (minimum). Recommend locatingaccumulator tank as close as possible to AUTO-purge/CEM panel.

Line Size from AUTO-purge/CEM to STACK-probe.

Line from AUTO-purge/CEM Panel to MASS-tron/CEM Panel.Via pre-manufactured umbilical or SS tubing.

Installation Requirements

AUTO-cal Relay Contact

Normal Flow Value

Flow and AUTO-cal Signals

DistanceTube Size

< 25'1/2" S.S. tube

25' to 50'3/4" S.S. tube

> 50'1" S.S. tube

DistanceTube Size

< 25'1/4" S.S. tube

25' to 200'3/8" S.S. tube

> 200'1/2" S.S. tube

ClosedOpen

20.0mA (100%)

15.2mA (70%)

4.0mA (0%)

STACK-probe w/Temperature and Insert Port

Typical Installation

In-Stack Probe Configurations – Single-Wall Stacks

Dual Traverse Schematic

Typical Installation

AUTO-purge/CEM Located on the Stack PlatformMASS-tron/CEM Located in the Instrumentation Enclosure

Flow Monitor Probe and Test Port Locations

STACK-probe Locations

NOTES:

1. Test ports should be located on a different axisthan flow monitor probe(s) to minimize disturbingthe flow being sensed by the probe(s) during40CFR60, Appendix A, Method 2 testing.

2. The distance from the flow monitor probe(s) ortest ports to an upstream flow disturbance is 2Dminimum, 8D desirable. The distance from theflow monitor probe(s) or test ports todownstream flow disturbance is D/2 minimum, 2Ddesirable.

3. The distance between the flow monitor probe(s)and the test port planes is usually only 6" to 12"due to practical limitations relative to stackplatform access. Flow disturbances created bythe test probe may affect flow monitor readingsduring 40CFR60, Appendix A, Method 2 testing.

4. Considered as flow disturbances are:– Any stack mounted equipment or structure that

protrudes or extends out into the air stream.– Any dimensional changes in the stack.– Any directional changes in the stack.

NOTES:

1. Test ports should be located on the same plane or elevation asthe flow monitor probe(s) to minimize disturbing the flow beingsensed by the flow monitor probe(s) during 40CFR60,Appendix A, Method 2 testing.

2. If test ports cannot be located on the same plane or elevationas the flow monitor probe(s) due to insufficient space orclearance, locate the test ports 2D upstream of the flowmonitor probe(s).

The distance from the flow monitor probe(s) or test ports to anupstream flow disturbance is 2D minimum, 8D desirable. Thedistance from the flow monitor probe(s) or test ports todownstream flow disturbance is D/2 minimum, 2D desirable.

4. Considered as flow disturbances are:– Any stack mounted equipment or structure that protrudes

or extends out into the air stream.– Any dimensional changes in the stack.– Any directional changes in the stack.

125-491 (7/07)

Air Monitor's Product Families of Air & Coal Flow Measurement Systems

P.O. Box 6358 • Santa Rosa, CA 95406 • P: 800-AIRFLOW • F: 707-526-9970www.airmonitor.com • amcsales@airmonito r.com

IBAMTM – Individual Burner Airflow MeasurementThe IBAMTM – Individual Burner Airflow Measurement probe is ideally suited for new orretrofit applications where a reduction in plant emissions and improvement in efficiencycan be obtained through accurate measurement of burner secondary airflo w. TheIBAMTM probe has been designed to accurately measure in the particulate laden, highoperating temperature conditions found in burner air passages.

CAMSTM – Combustion Airflow Management SystemThe CAMSTM – Combustion Airflow Management System has been designed to reliablyand accurately measure airflow in combustion airflow applications. The CAMS TM

contains the microprocessor based instrumentation to measure the airflow andmanage the AUTO-purge. The AUTO-purge is a high pressure air blowback systemthat protects the duct mounted flow measurement device from any degradation inperformance due to the presence of airborne particulate (flyash).

Air Monitor's duct mounted airflow measurement devices have been designed toaccurately and repeatedly measure air mass flow in power plants. The CombustionAir (CA) StationTM includes honeycomb air straightener to accurately measure in shorterstraight duct runs than any other flow measurement device. The VOLU-probe/SS TM

delivers accurate airflow measurement performance in the form of an insertion probe.Both devices feature Type 316 stainless steel flow sensing arrays.

Combustion Airflow Measuring Station & VOLU-probe/SSTM Traverse Probes

Pf-FLOTM – Pulverized Fuel Flow ManagementThe Pf-FLO TM system performs continuous and accurate fuel flow measurement inpulverized coal fired combustion applications, providing boiler operators with the real-time data needed to balance coal mass distribution between burners. Balanced fuelimproves combustion efficiency and lowers emissions while reducing in-furnaceslagging, coal layout, fuel slagging, and coal pipe fires.

VOLU-probe/SSTM Stainless Steel Airflow Traverse ProbesMulti-point, self-averaging, Pitot-Fechheimer airflow traverse probes with integral airflowdirection correcting design. Constructed of Type 316 stainless steel and available inexternally and internally mounted versions for harsh, corrosive or high temperatureapplications such as fume hood, laboratory exhaust, pharmaceutical, and clean roomproduction and dirty industrial process applications.

Engineering & Testing Services. Air Monitor offers complete engineering and testing to analyze air and coaldelivery systems. Air Monitor's field testing services use 3D airflow traversing and Pf- FLO coal flow measurementsystems for the highest possible accurac y. To ensure cost effective and accurate solutions, Air Monitor has full scalephysical flow modeling capability and in house Computational Fluid Dynamics (CFD). CFD analysis is used to analyzeflow profiles and design/redesign ductwork to improve overall performance. Full scale model fabrication and certifiedwind tunnel testing is used to develop application specific products that will measure accurately where no standard flowmeasurement can.

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