effects of oxygen concentration and coal composition on aerosol chemistry in oxy firing

Effects of Oxygen Concentration and Coal Composition on Aerosol

Chemistry in Oxy Firing

2010 AIChE Annual Meeting Salt Lake City, Utah

November 7-12, 2010

William J. MorrisDunxi Yu

Jost O. L. WendtDepartment of Chemical Engineering

University of Utah, Salt Lake City, UT 84112

Outline

• Objectives• Coals examined• Furnace, sampling, and analysis• Results• Conclusions

Objectives• Provide a comparison of three different coal aerosols under two

different oxy fired scenarios for predicting effects of coal composition on oxy firing.

• Examine aerosol chemistry under two different oxy fired scenarios: 27% O2 (~match heat flux of air) and 32% O2 (~match adiabatic flame temperature of air).

• Use aerosol chemistry to provide information for those who wish to make predictions of fouling/slagging within the furnace.

• Determine whether there are any significant differences in aerosol chemistry at varying O2 concentrations at conventional temperatures.

Coal ChemistryCoal Analysis (on an as-received basis)

Sample LOD Ash C H N S O (diff) VolatileMatter

FixedCarbon

HHVBTU/lb

% % % % % % % % %

Utah 3.18 8.83 70.60 5.41 1.42 0.53 13.21 38.60 49.39 12606

PRB 23.69 4.94 53.72 6.22 0.78 0.23 34.11 33.36 38.01 9078

Illinois 9.65 7.99 64.67 5.59 1.12 3.98 16.65 36.78 45.58 11598

Ash Analysis

Alas Al2O3

Caas CaO

Feas Fe2O3

Mgas MgO

Mnas MnO

Pas P2O5

Kas K2O

Sias SiO2

Naas Na2O

Sas SO3

TiAs

TiO2

% % % % % % % % % % %

Utah 14.52 6.11 5.09 1.39 0.02 0.59 0.57 60.89 1.41 2.33 0.88

PRB 14.78 22.19 5.2 5.17 0.01 1.07 0.35 30.46 1.94 8.83 1.3

Illinois 17.66 1.87 14.57 0.98 0.02 0.11 2.26 49.28 1.51 2.22 0.85

Coal Firing Rates and Combustion Conditions

Coal Coal feed rate (kg/h) Coal firing rate (kW)

Utah Skyline 4.50

36.64PRB 6.26

Illinois Bituminous 4.89

Combustion Mode

Oxidant Composition Practical Significance

OXY27 Oxyfuel Combustion 27%O2/73%CO2 Match AIR gas radiant heat flux

OXY32 Oxyfuel Combustion 32%O2/68%CO2 Match AIR adiabatic flame temperature

Sampling Systems

Laboratory CombustorPrimary

Coal feeder

3.8 m

Secondary

1.2 m

Heat exchanger #1 - 8

Flue gas1. Maximum capacity: 100 kW2. Representative of full scale units:

1. Self sustaining combustion2. Similar residence times and

temperatures3. Similar particle and flue gas

species concentrations3. Allows systematic variation of

operational parameters

Sampling port

This work: Uses once-through CO2 to simulate cleaned flue gas recycle with all contaminants and water removed.

Future work: Will use recycled flue gas.

Analysis

• Samples were collected with a Berner low pressure impactor.

• Size segregated samples were then analyzed using ICP-MS.

• Due to the difference in flue gas volume (m3) of OXY27 and OXY32 conditions, results were also normalized to ug per g of coal burned.

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

100.00

1000.00

10000.00

100000.00

1000000.00

Utah Skyline OXY27

Na2OMgOAl2O3SiO2P2O5K2OCaOTiO2MnOFe2O3As2O3SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/m

3)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

100.00

1000.00

10000.00

100000.00

1000000.00

Utah Skyline OXY32

Na2OMgOAl2O3SiO2P2O5K2OCaOTiO2MnOFe2O3As2O3SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/m

3)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

100.00

1000.00

10000.00

100000.00

1000000.00

PRB OXY27

Na2OMgOAl2O3SiO2P2O5K2OCaOTiO2MnOFe2O3As2O3SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/m

3)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

100.00

1000.00

10000.00

100000.00

1000000.00

PRB OXY32

Na2OMgOAl2O3SiO2P2O5K2OCaOTiO2MnOFe2O3As2O3SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/m

3)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

100.00

1000.00

10000.00

100000.00

1000000.00

Illinois OXY27

Na2OMgOAl2O3SiO2P2O5K2OCaOTiO2MnOFe2O3As2O3SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/m

3)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

100.00

1000.00

10000.00

100000.00

1000000.00

Illinois OXY32

Na2OMgOAl2O3SiO2P2O5K2OCaOTiO2MnOFe2O3As2O3SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/m

3)

Results

0.01 0.1 1 1010.00

100.00

1000.00

10000.00

Utah Fe2O3

Utah OXY27 FeUtah OXY32 Fe

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 101.00

10.00

100.00

1000.00

PRB Fe2O3

PRB OXY27 FePRB OXY32 Fe

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 101.00

10.00

100.00

1000.00

Illinois Fe2O3

Ill OXY27 FeIll OXY32 Fe

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 1010.00

100.00

1000.00

10000.00

Utah CaO

Utah OXY27 CaOUtah OXY32 CaO

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 1010.00

100.00

1000.00

10000.00

PRB CaO

PRB OXY27 CaOPRB OXY32 CaO

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 101.00

10.00

100.00

Illinois CaO

Ill OXY27 CaOIll OXY32 CaO

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 1010.00

100.00

1000.00

10000.00

Utah Na2O

Utah OXY27 Na2OUtah OXY32 Na2O

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 101.00

10.00

100.00

1000.00

PRB Na2O

PRB OXY27 Na2OPRB OXY32 Na2O

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 10100.00

1000.00

10000.00

Illinois SiO2

Ill OXY27 SiO2Ill OXY32 SiO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 10100.00

1000.00

10000.00

100000.00

Utah SiO2

Utah OXY27 SiO2Utah OXY32 SiO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 10100.00

1000.00

10000.00

PRB SiO2

PRB OXY27 SiO2PRB OXY32 SiO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 10100.00

1000.00

10000.00

Illinois SiO2

Ill OXY27 SiO2Ill OXY32 SiO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 100.01

0.10

1.00

PRB As2O3

PRB OXY27 As2O3PRB OXY32 AsO3

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

Illinois As2O3

Ill OXY27 As2O3Ill OXY32 As2O3

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

100.00

Utah SeO2

Utah OXY27 SeO2Utah OXY32 SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Results

0.01 0.1 1 100.01

0.10

1.00

10.00

Illinois SeO2

Ill OXY27 SeO2Ill OXY32 SeO2

Aerodynamic Particle Diameter (um)

dM/d

logD

p (u

g/g

coal

)

Conclusions

• Fine fragmentation mode (~1 um) is not affected by small changes in PO2 at conventional temperatures.

• Coal composition still plays the dominant role in aerosol chemistry.

• Only differences are noticed in the ultra-fine region <100nm. This is the condensed vapor phase mode and is likely due to a hotter flame temperature yielding increased vaporization.

Acknowledgements

• Financial support from the Department of Energy under Awards DE-FC26-06NT42808 and DE-FC08-NT0005015

• David Wagner, Ryan Okerlund, Brian Nelson, Rafael Erickson, and Colby Ashcroft Institute for Clean and Secure Energy, University of Utah

• Diego Fernandez and his team of analytical chemists in the Department of Geology and Geophysics, University of Utah