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CHEC Annual Day, 2009
Ash Deposition and Shedding in Biomass Suspension-Fired Boilers
Muhammad S. BashirPhD Student (01-09-2008 to 31-08-2011)
Supervisors: Kim Dam-JohansenPeter A. JensenFlemming FrandsenStig Wedel
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Project Objectives
“Optimal use of Biomass in large suspension-fired boilers.”
• Ash deposition and removal behavior in the boiler chamber and superheater region (convective pass).
• Transient model based description of key processes responsible for ash deposition and shedding.
• Influence of load, operation conditions and fuel mixing on ash deposition and shedding.
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Ash Deposition during Biomass Combustion
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
L. Tobiasen et al; Fuel Processing Technology, 88 (2007) 1108-1117.
Biomass (straw) K, Cl, S
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Initial Experiments on Amagerværket Unit 2: Co-firing straw and wood
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
80% Straw
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Deposit Probe Weight and Heat Uptake
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
Test No. 1 (SH) 2 (SH) 3 (SH) 4 (SH) 5 (TB)
Straw (%) 35 65 80 100 0
Wood (%) 65 35 20 0 100
Flue Gas Temp. (oC) 846 841 851 821 586
Weight Uptake (g/m2) 1080 1410 1480 1700 (20)
Heat Uptake (kW/m2) 22 23 22 24 10
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Deposit Characterization for different straw shares
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
80 %
100 %
35 %
65 %
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Ash Enrichment
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
Ca K Si S Cl0
5
10
15
20
25
30
35
40
45
Fuel Ash Fly ash (Suspension-firing, 80% straw)Fly ash (Grate-firing, 100% straw)
Wt
%
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Front Deposits Elemental Composition
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
Ca K Si S Cl0
5
10
15
20
25
30
35% Straw 100 % Straw
wt
%
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Conclusion
• Deposition rate increases for increase in straw share.
• Deposit layers differ in terms of color, thickness, hardness and composition for change in fuel composition.
• Deposits are more sintered in the upper layer for 100% straw-firing.
• Deposits and fly ash contains significant amounts of Ca and Si during suspension-firing.
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Future Work• Final design of vertical probe for ash deposition/shedding
in the furnace region.
• Modeling of ash deposition/shedding in the furnace region.
• Ash deposition/shedding tests at Amagerværket Unit 1 (co-fired with coal) using horizontal sootblowing probe.
• Ash deposition/shedding tests at Amagerværket Unit 1 (co-fired with coal) using vertical probe.
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
DTU Chemical Engineering, Technical University of Denmark
CHEC Annual Day, 2009CHEC Annual Day, 2009
Acknowledgment
• Dr. Johan Wadenbäck/Søren Thaaning., Vattenfall A/S
• Energinet.dk for PSO project funding
Objectives Background Experiments Results and Discussion Conclusions Future Work Acknowledgment
Tak for opmærksomheden/
Thanks for the Attention !