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Recent Measurements of ISP Recent Measurements of ISP Concentration, Size, and Chemistry Concentration, Size, and Chemistry
in a Recovery Boilerin a Recovery Boiler
Colloquium on Black Liquor Combustion and GasificationPark City, UTMay 15, 2003
Chris ShaddixSandia National Labs
Livermore, CA
Don HolveProcess Metrix San Ramon, CA
and
Rick WesselBabcock & Wilcox
Barberton, OH
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Background and MotivationBackground and Motivation
roles of carryover and fume to deposit formation and pluggageof superheater and convection pass fairly well establishedmagnitude of problem of intermediate size particles (~ 5–100 µm) unclear
ISPs difficult to quantify (size and concentration) in fume-laden flowISP formation routes and chemistry unclearmicroscopic examination of deposit cross-sections necessary to evaluate end effect
previous sampling at Weyerhaeuser Longview boiler showed small concentrations of ISP in convection pass, but significant levels at superheater entrancedesire data for comparison at superheater entrance, at more modern, less-burdened boiler (IP RB#3, Courtland, Alabama)
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Courtland Measurement CampaignCourtland Measurement Campaign
Aug 13–16, 2002measurements performed:
water-cooled pitot tube/thermocouple probefume mass extractive probevirtual cyclone sampling probe (for ISP)PCSV laser scattering for in situ ISP measurement (PMC)impaction disk sampling of particulate (optical/SEM microscopy)laser-induced breakdown spectroscopy (LIBS) for in situ measurement of particulate chemistryIR camera deposit imaging (Diamond Power)air duct profiling and liquor and fly ash chemistry (MTI)strain gauge measurements of deposit mass growth (IP)
all sampling probes (other than fume probe) used at maintenance beam doors (front wall, 3 feet above nose arch)
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IP Courtland Recovery #3 Operation IP Courtland Recovery #3 Operation –– Aug. 2002Aug. 200293% MCR (Manuf. Continuous Rating)Firing Rate
Single-Drum DesignBoiler Steam
B&W 3-level Air systemAir Delivery
4 B&W Splash Plate NozzlesOne nozzle centered on each wall
70.6%
Liquor DeliveryNozzle ArrangementBL Solids Content
(335,600 kg/hr)740,000 lb/hrTotal Air Flow
(240,400 kg/hr)(482ºC)(8.756 MPa)
530,000 lb/hr900ºF
1270 psig
Steam Flow rateSteam TemperatureSteam Pressure
Pri 38.3%, Sec 35.4%, Ter 26.3%Air Flow Distribution
(127ºC)(117 kPa)
260ºF17 psig
BL TemperatureNozzle Pressure
(1,761 t/day)(2.65 MWt/m2)
3.88×106 lb/day0.84×106 Btu/ft2-hr
Virgin DS Flow RateHeat Input per Plan Area
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Liquor and Fly Ash AnalysisLiquor and Fly Ash Analysis
Virgin Liquor
As-Fired Liquor
Dry solids (%) 70.5 70.6 HHV (Btu/lb d.s.) 5480 5340 wt% d.s. wt% d.s. Total S 6.69 7.10 Sulfate 4.54 4.64 C 31.8 31.7 H 3.8 3.6 N 0.11 0.13 Na 21.5 21.5 K 1.89 1.89 Cl 0.42 0.44 ESP ash wt% in ash EF Na 27.8 K 4.05 1.6 Cl 1.54 2.6 Sulfate 58.8 Carbonate 2.9
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Maintenance Beam LevelMaintenance Beam Level
Sampling occurred through near-center and near-right doorways
Overview of maintenance beam level on front wall (before removal of two of the beams)
LIBS probe inserted into portPCSV probe entering port
modified doorway with open sampling port
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Notes:• mean temperature is ~ 960 deg C at
maintenance beam level• mean velocity is 9 m/s at 1-m depth and
11 m/s at 2-m depth• standard deviation of velocity is 1.25–2 m/s in
vertical direction and 1.5–3 m/s in horizontal plane (ignoring direct sootblower influence)
Temperature and Velocity MeasurementsTemperature and Velocity Measurements1000
980
960
940
920
900
Tem
pera
ture
(°C
)
140120100806040200Time (s)
2-m depth 1-m depth
18
16
14
12
10
8
6
4
Ver
tical
Vel
ocity
(m
/s)
140120100806040200Time (s)
2-m depth 1-m depth
15
10
5
0
-5
-10
Hor
izon
tal V
eloc
ity (
m/s
)
140120100806040200Time (s)
sootblowers activated in 1st SH
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Fume Mass ConcentrationFume Mass Concentration
H2O in
H2O
3 m
fume samples collected on 10th floor (upper furnace), through inspection portsN2-purged probe provided ~ 3:1 dilutionlimited cooling water flow restricted probe penetration and sample timeprobe operated non-isokinetically, to discriminate against ISPcritical flow orifice sampling system recorded instantaneous gas sampling ratefilter mass collection verified through both gravimetric and filter wash analysisinner probe deposition measured through probe wash analysis
Result: Fume concentration = 7.3–8.0 g/Nm3
Schematic of sampling probe
Photo of exposed and fresh filters
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Virtual Impaction Sampling ProbeVirtual Impaction Sampling Probe
new design for aerodynamically separating ISP from fumefilter observed to rapidly plugoperation of annular pump induces lower sample suction than purge – most of purge pulled into annulusSEM on filter samples shows predominantly fumeassumption of constant purge ‘loss’ allows estimation of total particle concentration
Result: Total collected particulate concentration ~ 9.0–10.5 g/Nm3
design concept of sampling probe
SEM of particles on collection filter
N2
N2-diluted ISP
fume-ladenbulk flow
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Light Scattering Measurement of ISP Light Scattering Measurement of ISP –– PCSVPCSVmeasures near-forward light scattering from low-power, 670 nm, cw laserinterprets with Mie theory; measurement geometry minimizes sensitivity to particle shape or optical propertiesmeasures particle sizes, speed, and concentrationfor boiler sampling, implemented in 3” OD optical probe that fits within 3.75” OD water-jacketfor recovery boiler application, est. ISP mass uncertainty ~ 30%
PCSV operating principle
photo of boiler optical probe
Focusing lens
Particle flow field
Receiver lens
Transmitted beam
Scattered light
Mask
Beam stop
Slit
Fiber coupling to detector
Illumination laser
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ISP Size Distribution ISP Size Distribution –– PCSV DataPCSV Data
10-1
100
101
102
103
104
105
106
dN/dlnD (1/cm3)
12 3 4 5 6 7 8
102 3 4 5 6 7 8
100
diameter (µm)
particle number density distribution particle mass distribution
Notes:• all data are 4–5 min. averages• PCSV results similar for two sample ports and 1-m and 2-m insertion depths, and for
various locations of active sootblowers• dual-beam PCSV captures back-side of fume concentration peak• ISP size distributions similar to Longview boiler – perhaps more ISP here for large sizes
68
0.01
2
4
68
0.1
2
4
68
1
2
dM/d
lnD
(g/
m3 )
12 3 4 5 6 7 8 9
102 3 4 5 6 7 8 9
100diameter (µm)
PCSV 'data' points exponential fit median dataset
from Longview boiler
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Mass Concentration of ISPs at Courtland Mass Concentration of ISPs at Courtland (from PCSV)(from PCSV)
Total mass concentration of ISPs ~ same at Courtland and Longview, though is quite variable over both short and intermediate time scalesFume mass from 1.2–2 µm is steady at 0.8 ± 0.15 g/Nm3
4
3
2
1
0
Mass Concentration (g/Nm3)
12:00 PM8/14/2002
1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM
Time
range of values at Longviewthermoprobe port
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ISP Mass and ISP Mass and Superheater Superheater Deposit BuildupDeposit Buildup4
3
2
1
0
Mass Concentration (g/Nm3)
12:00 PM8/14/2002
2:00 PM 4:00 PM
Time
1.2
1.1
1.0
0.9
0.8
Strain (a.u.)
SH#1
SH#2
SH#4
Only correlation appears to be for superheater #4 strain gauge – may be fortuitous
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Impaction Disk MeasurementsImpaction Disk Measurements(30x Optical Microscopy)(30x Optical Microscopy)
Courtland Longview
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Analysis of Courtland Impaction DisksAnalysis of Courtland Impaction Disksperformed manual particle counting on optical microscopy images need to correct for size dependence of impaction efficiency
calculate impaction efficiency from correlation for stripsassume unity sticking efficiency on fume-coated surface
corrected impaction counting ISP concentration lower than PCSV by factor of 2–3 (seems reasonable)
6
80.01
2
4
6
80.1
2
4
6
81
2
dM/dlnD (g/Nm3)
102 3 4 5 6 7 8 9
100
diameter (µm)
PCSV data fit impaction plate (mean) impaction correction (11 m/s) impaction correction (6 m/s) impaction correction (4 m/s)
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ISP Particle Chemistry ISP Particle Chemistry –– Results from Results from SEMSEM--EDX on Impaction DisksEDX on Impaction Disks
Similar depletions in K, Cl, and S with increasing size, up to ~ 100 µm
2.5
2.0
1.5
1.0
0.5
0.0
Enrichment Factors (K and Cl)
300250200150100500
Particle Size (µm)
1.0
0.8
0.6
0.4
0.2
0.0
Sulfidity, S/(Na2 +K2 )
K
Cl
S
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In Situ Particle Chemistry In Situ Particle Chemistry –– Sample Sample Results from LIBS MeasurementsResults from LIBS Measurements
700
600
500
400
300
200
Emis
sion
Int
ensi
ty (ar
b. u
nits
)
265260255250245240
Wavelength (nm)
C
B
Si
Mn400
300
200
100
0
LIBS
pea
k ar
ea (
arb.
uni
ts)
2.52.01.51.00.50.0
time (minutes)
Mn
Si
B
1000-shot (4-min.) average spectra in trace metal-rich 250 nm region
single-shot time record of trace metal signals in 250 nm region
difficulty of S detection with LIBS hinders differentiation between fume and ISP chemistryInvestigated ISP detection via trace metals:
single-shot trace metal detection possible with linear spectrometer/ICCD systemsingle-shot trace metal detection not possible with echelle cross-dispersion spectrometer system
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SummarySummaryExtensive measurement campaign conducted at IP’s Courtland recovery boiler #3Fume mass loading in upper furnace found to be ~ 8 g/Nm3
ISP mass loading entering superheaters determined by PCSV to be 0.3–3.5 g/Nm3, or ~ 4–45% of fume mass loading (similar to result at Weyerhaeuser Longview boiler)
can confidently conclude that ISP contribute significantly to deposition in convection passhigh variability in ISP concentrations suggests improved control is possible
Correlation of ISP concentrations with strain gauge data evident for one of three SH sectionsSEM-EDX of impacted particles shows significant depletion of K, Cl, and S in larger ISP
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AcknowledgmentsAcknowledgmentsMike Gregory and Andy Jones from International PaperDoug Scott, Dennis Morrison, Gil Hofacker, Sal Birtola, and Trey Cauley from SandiaDarren Garvis from Process MetrixAlarick Tavares from Diamond PowerKen Nichols and Bill Trout from Weyerheauser Co.Funding provided by DOE/OIT–AF&PA Agenda2020 projects in Sensors & Control and Energy Performance
