[PPT] - Ash Deposition and Shedding in Straw and W ood Suspension-Fired PowerPoint Presentation

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Ash Deposition and Shedding in Straw and W ood Suspension-Fired Boilers : Full-scale Measurem ents

Student: Muham m ad S. Bashir Supervisors: Professor Kim Dam -Johansen

Asso. Prof. Peter A. Jensen
Asso. Prof. Flem m ing Frandsen
Asso. Prof. Stig W edel

CHEC Research Centre, Technical University of Denm ark

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DTU Chem ical Engineering Technical University of Denmark

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Background
Experiments
Experimental Objectives
Materials and Methods
Results and Discussion
Experimental Set Up
Quantification of Deposit Buildup
Deposit Shedding using Artificial Sootblowing
Elemental Release of Major Ash Components
Conclusions/ Experimental Findings

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Presentation Outline

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DTU Chem ical Engineering Technical University of Denmark

Ash Deposition during Biom ass Com bustion

L. Tobiasen et al; Fuel Processing Technology, 88 (2007) 1108-1117.

Biomass (straw) K, Cl, S

Increased risk of fouling/slagging on heat exchange surfaces.

AMV2

Superheater Region

Background Experiments Results and Discussion Conclusions Acknowledgment

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DTU Chem ical Engineering Technical University of Denmark

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Boiler Configuration : AMV1

4 Param eter AMV1 Capacity (wood, straw) 350, 320 MWth Wood, Straw pellets (full load) 20 kg/ s Steam Data Superheater ( oC) 540

Background Experiments Results and Discussion Conclusions Acknowledgment

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DTU Chem ical Engineering Technical University of Denmark

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Boiler Configuration : AMV2

5 Param eter AMV2 Capacity (wood, straw) 250 MWth Wood, Straw pellets (full load) 60 t/ h Steam Data Superheater ( oC) 480

Background Experiments Results and Discussion Conclusions Acknowledgment

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DTU Chem ical Engineering Technical University of Denmark

Experim ents

Measurement of extent of boiler fouling/ slagging by means
f an ash deposition/ shedding probe.
Influence
f

fuel type, boiler load, probe metal temperature and probe exposure time on deposition rate, heat uptake and deposit characteristics.

Investigation of PIP needed to remove the deposits of

different exposure time and probe surface temperature.

Investigation of residual ash and deposits chemistry.

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Background Experiments Results and Discussion Conclusions Acknowledgment

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Deposition/ Shedding Probe

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600

Background Experiments Results and Discussion Conclusions Acknowledgment

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DTU Chem ical Engineering Technical University of Denmark

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Experim ental Setup Description ( AMV 1 )

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Background Experiments Results and Discussion Conclusions Acknowledgment

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DTU Chem ical Engineering Technical University of Denmark

Experim ental Resum e : AMV2

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Test No. 1 3 2 4 5 Straw (% )

35 65 80 100

Ash (% ) 4.21 4.99 5.38 5.85 3.3 Probe Temp. ( oC) 500 500 500 500 500 Exposure Time (h)

90 72 124 76 24

Boiler Load (% )

46 63 50 53 52

Background Experiments Results and Discussion Conclusions Acknowledgment

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DTU Chem ical Engineering Technical University of Denmark

Experim ental Resum e : AMV1

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Test No. 1 2 3 5 4 Straw (% )

80 65 35 50 50

App. Ash (% )

5.2 4.0 2.4 3.4 3.4

Probe Temp. ( oC)

500 600 500 500 (600) 500

Exp. Time (h)

56 45 185 168 73

Boiler Load

66 57 62 64 86

Oil Share (% )

12.9 13.5 2.4 7.1 4.8

Background Experiments Results and Discussion Conclusions Acknowledgment

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0-10 0-10 0-10 1.0 1.0 1.0 550 550 550 335 434 212 62 60 60 2.7 5.3 6.9

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DTU Chem ical Engineering Technical University of Denmark

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AMV1 : Prim ary Data ( 1 2 0 s) : 5 0 % Straw ( flue gas: 8 4 3 oC)

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20 40 60 80 100 120 140 160 180 600 800 1000 Time [h] Gas Temp.(oC) Thermocouple 20 40 60 80 100 120 140 160 180 5000 10000 Time [h] (g/m2) Weight Uptake 20 40 60 80 100 120 140 160 180 50 100 Time [h] (kW/m2) Heat Uptake 20 40 60 80 100 120 140 160 180 80 100 120 Sootblower

0 -185 h (500)

Background Experiments Results and Discussion Conclusions Acknowledgment

Actual flue gas temp. (suction pyrometer, Qualitative trend is same as of thermocouple)

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AMV1 : Prim ary Data ( 1 2 0 s) : 5 0 % Straw ( avg. flue gas: 8 8 0 oC)

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20 40 60 80 100 120 140 160 600 800 1000 Time [h] Gas Temp.(oC) Thermocouple 20 40 60 80 100 120 140 160 1 2x 10

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Time [h] (g/m2) Weight Uptake 20 40 60 80 100 120 140 160 40 80 Time [h] (kW/m2) Heat Uptake 20 40 60 80 100 120 140 160 80 100 120 Sootblower

0 -30 h (500) 30 -94 h (600) 94-145 h (500) 145 -168 h ( 600)

Background Experiments Results and Discussion Conclusions Acknowledgment

Actual flue gas temp. (suction pyrometer, Qualitative trend is same as of thermocouple)

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Flue Gas Tem perature and Heat Uptake

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500 550 600 650 700 750 800 850 900 950 10 20 30 40 50 60 70 80 90 100 Gas Temp.(oC) (kW/m2)

y = 0.1247*x - 55.35

Heat Uptake linear 500 550 600 650 700 750 800 850 900 950 10 20 30 40 50 60 70 80 90 100 Gas Temp.(oC) (kW/m2)

y = 0.1427*x - 70.12

Heat Uptake linear 500 550 600 650 700 750 800 850 900 950 10 20 30 40 50 60 70 80 90 100 Gas Temp.(oC) (kW/m2)

y = 0.06928*x - 29.89

Heat Uptake linear

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Background Experiments Results and Discussion Conclusions Acknowledgment

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DTU Chem ical Engineering Technical University of Denmark

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Brief Results of Tests

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Test No. 1 2 3 5 4 Straw (% )

80 70 50 50 30

Ash (% )

5.0 4.3 3.4 3.4 3.0

Probe Temp. ( oC)

500 600 500 500 (600) 500

Exp. Time (h)

56 45 185 168 73

Boiler Load

66 57 62 64 86

Oil Share (% )

12.9 13.5 2.4 7.1 4.8

Flue Gas Temp. Mean ( oC)

852 821 843 880 918

Weight Uptake Final (kg/ m 2)

3.78 4.95 3.07 16.26 7.34

Heat Uptake Mean(kW/ m 2)

34 21.1 35.0 23.3 41.1

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Background Experiments Results and Discussion Conclusions Acknowledgment

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10 5 1.0 0.8 0.7 550 550 550 335 434 212 62 60 60 2.7 5.3 6.9 774 724 788 1.95 1.82

24.0

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DTU Chem ical Engineering Technical University of Denmark

Overall Com parison of W eight Uptake of Different Full Scale Measurem ents ( 4 5 h)

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Boiler Fuel Analysis Probe Temp. Flue gas Temp. Final Weight Signal Ref. Tests

Ash K Cl

C
C

kg/ m 2

Avedøre Test 1

5.5 0.69 0.32 500 1020 9.50 [ 11]

Avedøre Test 2

4.7 0.92 0.35 500 784 1.50 [ 6]

Amager Unit 2 (Test 4)

5.9 0.83 0.40 500 830 1.70

Amager Unit 1 (Test 1)

5.0

500

852 2.20

Amager Unit 1 (Test 3)

3.4

0.25

500 843 0.45

Amager Unit 1 (Test 4)

3.0

500

918 4.90

Background Experiments Results and Discussion Conclusions Acknowledgment

Amager Unit 1 (Test 2)

4.3

600

821 4.95

Amager Unit 1 (Test 5)

3.4

600

880 9.60

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DTU Chem ical Engineering Technical University of Denmark

Overall Com parison of W eight Uptake of Different Full Scale Measurem ents ( 7 2 -7 7 h)

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Boiler Fuel Analysis Probe Temp. Flue gas Temp. Final Weight Signal Ref. Tests

Ash K Cl

C
C

kg/ m 2

Avedøre Test 1

5.5 0.69 0.32 500 1022 15.0 [ 11]

Avedøre Test 2

4.7 0.92 0.35 500 784 2.40 [ 6]

Amager Unit 2 (Test 4)

5.9 0.83 0.40 500 830 1.67

Amager Unit 1 (Test 3)

3.4

0.25

500 843 1.01

Amager Unit 1 (Test 4)

3.0

500

918 7.34

Background Experiments Results and Discussion Conclusions Acknowledgment

Amager Unit 1 (Test 5)

3.4

600

880 10.0

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Ash Deposit Rem oval using Artificial Sootblow ing Probe ( Exam ple: Test 3 ( 5 0 0 ) )

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60 70 80 90 100 110 120 600 800 1000 Time [h] Gas Temp.(oC) Thermocouple 60 70 80 90 100 110 120 600 800 1000 (oC)

Suction Pyrometer

60 70 80 90 100 110 120 5000 10000 Time [h] (g/m2) Weight Uptake 60 70 80 90 100 110 120 40 80 Time [h] (kW/m2)

Heat Uptake

60 70 80 90 100 110 120 80 100 120 Sootblower

Shedding through artificial sootblowing Shedding through plant sootblowing Background Experiments Results and Discussion Conclusions Acknowledgment

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Artificial Deposit Rem oval: I m age Analysis

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Weight Signal : 8747.18 g/m2 Weight Signal : 1584.83 g/m2

Probe Exposure Time : 91.2 h Flue gas temperature : 825 C Target Probe Temperature : 500 oC Straw Share : 50 % Boiler Load : 65 %

Background Experiments Results and Discussion Conclusions Acknowledgment

Image Before Deposit Removal Image After Deposit Removal

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DTU Chem ical Engineering Technical University of Denmark

Air Pressure and PI P

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Background Experiments Results and Discussion Conclusions Acknowledgment

50 100 150 200 250 300 50 100 150 200 250 300 350 400 450 500 PIP (kPa) Air Pressure (kPa)

20 cm 15 cm 13 cm 11 cm 9 cm 7 cm 5 cm

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DTU Chem ical Engineering Technical University of Denmark

I m pact of Probe Exposure Tim e and Tem perature on Deposit Rem oval

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Background Experiments Results and Discussion Conclusions Acknowledgment

0,1 1,0 10,0 100,0 50 100 150 200 250 % Deposit Removed PIP (kPa)

500 oC (Probe Temperature)

30 h (1695 g/m2) 72 h (7100 g/m2) 91 h (9090 g/m2) 120 h (12750 g/m2) 144 h (15006 g/m2)

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DTU Chem ical Engineering Technical University of Denmark

I m pact of Probe Exposure Tim e and Tem perature on Deposit Rem oval

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Background Experiments Results and Discussion Conclusions Acknowledgment

0,1 1,0 10,0 100,0 50 100 150 200 250 % Deposit Removed PIP (kPa)

600 oC (Probe Temperature)

46 h (4494 g/m2) 76 h (500 C for initial 30 h) ( 11123 g/m2) 95 h (14024 g/m2) 167 h (17850 g/m2)

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DTU Chem ical Engineering Technical University of Denmark

Fly Ash Elem ental Com position ( AMV2 )

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Background Experiments Results and Discussion Conclusions Acknowledgment

10 20 30 40 50 60 10*Al2O3 10*Fe2O3 10*MgO 10*Na2O K2O P2O3 CaO SiO2 SO3 Cl Composition (wt. %)

Grate boiler (Fuel ash) Grate boiler (Fly ash) Suspension boiler (Fuel ash) Suspension boiler (Fly ash)

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DTU Chem ical Engineering Technical University of Denmark

Deposit Elem ental Com position ( AMV2 )

0,0 5,0 10,0 15,0 20,0 25,0 30,0 Al Ca Fe K Mg Na P Si S Cl

wt % Elements 35% Straw (Front Upper Layer) 100 % Straw (Upper Front Layer) 23

Background Experiments Results and Discussion Conclusions Acknowledgment

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Prelim inary Conclusions

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Deposits are more sintered in the windward direction during pure straw-firing. Deposits and fly ashes obtained during suspension-firing contain significant amounts of Ca and Si. The final deposit weight uptake is not higher compared to biomass grate-firing at almost similar conditions.

Background Experiments Results and Discussion Conclusions Acknowledgment

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Prelim inary Conclusions

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Image analysis reveal that deposit shedding is primarily through debonding. Deposits of less than 91 h exposure time are easy to remove and PIP needed is less than 55 kPa at 500oC temp. With increase in probe surface temperature from 500 to 600 oC, PIP needed to remove the deposits increases. Natural shedding is possible at higher flue gas temperatures (> 940

C),

but temperature needs to remain higher as lower temperature fluctuations are not helpful.

Background Experiments Results and Discussion Conclusions Acknowledgment

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Acknow ledgm ent

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Dr. Johan Wadenbäck/ Søren Thaaning., Vattenfall A/ S
Energinet.dk for PSO project funding

Background Experiments Results and Discussion Conclusions Acknowledgment

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Questions?

Many Thanks!

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