Overview of Factors Affecting Fouling in Recovery...
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Overview of Factors Affecting Overview of Factors Affecting Fouling in Recovery Boilers Fouling in Recovery Boilers Honghi Tran Honghi Tran University of Toronto University of Toronto Colloquium on Black Liquor combustion and Gasification, Colloquium on Black Liquor combustion and Gasification, Park City, May 12 Park City, May 12 - - 16, 16, 2003
Transcript of Overview of Factors Affecting Fouling in Recovery...
Overview of Factors Affecting Overview of Factors Affecting Fouling in Recovery Boilers Fouling in Recovery Boilers
Honghi TranHonghi TranUniversity of TorontoUniversity of Toronto
Colloquium on Black Liquor combustion and Gasification, Colloquium on Black Liquor combustion and Gasification, Park City, May 12Park City, May 12--16, 16, 2003
Fouling
Plugging
Three Principal Parameters Determining the Rate of Fouling
ParticleConcentration
ParticleStickiness
Sootblowing Efficiency
ParticleConcentration
ParticleStickiness
Deposition
Less StickyLow Conc.
ParticleConcentration
ParticleStickiness
Deposition
Less StickyLow Conc.
SootblowingEfficiency
Fouling/Plugging
High Efficiency
Types of Particles
Carryover500 µm
(100 µm - 3 mm)
ISP20 µm
(1 - 100 µm)
Fume0.5 µm
(0.1 - 1 µm)
Carryover Fume
ISP
ISP Covered with Fume
Economizer
Superheater
Boiler Bank
Fume ISP
Carryover
Three Principal Parameters Determining the Rate of Fouling
ParticleConcentration
ParticleStickiness
Sootblowing Efficiency
Factors Affecting CarryoverConcentration
• Firing load• Air flow rate and distribution• Black liquor properties• Black liquor sprays
• Nozzle design• Liquor temperature and pressure• Liquor properties
Liquor Spray Study at Domtar Espanola
May 2, 2003
Three Principal Parameters Determining the Rate of Fouling
ParticleConcentration
ParticleStickiness
Sootblowing Efficiency
Factors Affecting Carryover Stickiness (Liquid Content)
• Particle composition• Black liquor composition (Cl, K)• Black liquor droplet size
• Particle temperature• Flue gas temperature• Retention time• All burning particles are sticky!
U of T Entrained Flow Reactor
Gas burner
Sample
Probe
Furnace9 m
Particles
Camera
0 mole% Cl/(Na+K)0 mole% Cl/(Na+K)
55
1010
2020
11
420 - 850 µm
300 - 420 µm
150 - 300 µm
Effect of Particle Size on Deposition
Mill “A” Black Liquor EFR Temp. = 800oC
Sticky Temperature540
560580
600
780
660640
620
800760
820
740720
700680
0
5
10
15
20
25
30
0 1 2 3 4 5Cl/(Na+K) mole%
K/(N
a+K
) mol
e%20 mole% CO3/(Na2+K2)
717oC
587oC
Prediction of Sticky Temperature
Black Liquor Composition
Particle Composition
Sticky Temperature
Carryover
Na2CO3(65)
Na2SO4(30)
NaCl (2)K-salts (2.5) Carbon/
impurities (1)
Composition (Wt%)
(50)
(45)
(2)(2.5) (1)
Oxidized Smelt
Carryover Particle Composition Continuously Changes
• Cl, K and carbonate contents are lower than previous thought
• S (sulphate and sulphide) content is higher • Changes depend strongly on particle size,
temperature and excess O2
Boiler 2
100 µm
20 sec5 sec
Boiler 2
100 µm
20 sec5 sec 20 sec5 sec
Factors Affecting SootblowingEfficiency
• Sootblower nozzle design• Blowing sequence and frequency• Deposit adhesion strength
• Composition• Tube temperature
• Tube arrangement
Three Principal Parameters Determining the Rate of Fouling
ParticleConcentration
ParticleStickiness
Sootblowing Efficiency
Deposit Removal Studies• Laboratory studies
• Composition• Tube surface temperature• Particle size
• Numerical simulation• Free jet• Jet-deposit interaction
• Field studies• Sootblowing efficiency
1.81.61.4
1.00.80.60.40.20.0
1.2
2 10 12 14 164 6 8mole% Cl/(Na+K)
PIP
(MPa
)
Probe temp.=400oC0% K% CO3
Effect of Chloride on Removal
Min
imum
PIP
(MPa
)
1.4
1.2
0.80.60.40.20.0
1.0
mole% K/(Na+K)0 5 10 15 20 25
5 mole%Cl/(Na+K)
2 mole% Cl/(Na+K)
Effect of Potassium on Removal
Probe temp.=400oC0% CO3
Nozzle
Pitot tube
Air Jet ImpingementApparatus
TubeArrays
Sootblowing Efficiency Studies at Domtar Espanola
May 2, 2003
Conclusions
ParticleConcentration
ParticleStickiness
Deposition
Less Sticky
Low Conc.
SootblowingEfficiency
Fouling/Plugging
High Efficiency
ParticleConcentration
ParticleStickiness
Deposition
Less Sticky
Low Conc.
SootblowingEfficiency
Fouling
High Efficiency
Alstom PowerAndritzAracruz CeluloseBabcock & WilcoxBoise Paper SolutionsBowaterCanforClyde-BergemannDaishowa-Marubeni
DomtarGeorgia Pacific International PaperIrving Pulp & PaperKvaerner PulpingMeadWestvacoStora-Enso ResearchVotorantim Celulose E PapelWeyerhaeuser Paper
NSERC
AcknowledgementsResearch Consortium on “Increasing Recovery Boiler Throughput and
Reliability of Recovery Boilers and Lime Kilns”
