Overview of Factors Affecting Fouling in Recovery Boilerswhitty/blackliquor/... · • Sootblower...

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Overview of Factors Affecting Fouling in Recovery Boilers Honghi Tran University of Toronto Colloquium on Black Liquor combustion and Gasification, Park City, May 12-16, 2003 Fouling Plugging

Transcript of Overview of Factors Affecting Fouling in Recovery Boilerswhitty/blackliquor/... · • Sootblower...

Page 1: Overview of Factors Affecting Fouling in Recovery Boilerswhitty/blackliquor/... · • Sootblower nozzle design ... Nozzle Pitot tube Air Jet Impingement Apparatus Tube Arrays Sootblowing

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Overview of Factors Affecting Fouling in Recovery Boilers

Honghi TranUniversity of Toronto

Colloquium on Black Liquor combustion and Gasification, Park City, May 12-16, 2003

Fouling

Plugging

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Three Principal Parameters Determining the Rate of Fouling

ParticleConcentration

ParticleStickiness

Sootblowing Efficiency

ParticleConcentration

ParticleStickiness

Deposition

Less StickyLow Conc.

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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)

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Carryover Fume

ISP

ISP Covered with Fume

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Economizer

Superheater

Boiler Bank

Fume ISP

Carryover

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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

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Liquor Spray Study at Domtar Espanola

May 2, 2003

Three Principal Parameters Determining the Rate of Fouling

ParticleConcentration

ParticleStickiness

Sootblowing Efficiency

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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

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0 mole% Cl/(Na+K)

5

10

20

1

420 - 850 µm

300 - 420 µm

150 - 300 µm

Effect of Particle Size on Deposition

Mill “A” Black Liquor EFR Temp. = 800oC

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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

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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

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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

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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

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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 RemovalM

inim

um P

IP (M

Pa)

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

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Nozzle

Pitot tube

Air Jet ImpingementApparatus

TubeArrays

Sootblowing Efficiency Studies at Domtar Espanola

May 2, 2003

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Conclusions

ParticleConcentration

ParticleStickiness

Deposition

Less Sticky

Low Conc.

SootblowingEfficiency

Fouling/Plugging

High Efficiency

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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”