Biomass Replacing in a Pulverized Coal Utility Boiler - Final Version

8/14/2019 Biomass Replacing in a Pulverized Coal Utility Boiler - Final Version

1/19

Biomass Replacing in a Pulverized Coal Utility Boiler:

Prediction of Performance and Pollutant Emission Using

CFD Tools

Antofagasta, Chile.

Cornejo P. (1), Prez R.(2), Flores M.(3), Garca X.(2)(1) Mechanical Engineering Department, University of Concepcin

(2) Chemical Engineering Department, University of Concepcin

(3) Technological Development Unit, University of Concepcin


2/19

Conclusions

Results

Model Validation

Mathematical Models

Case to Study

Photography : Campanil University of Concepcin


3/19

Photography Unit 15 . Tocopilla, Chile.

What are the effects that will be produce by the inclusion of

biomass in the Unit-15?

o

Boiler type :Pulverized Coal Boilero Location : Tocopilla, Chile.

o Owner : E-CL, GDF-Suez

o Power : 150 MWe

o Number of Burners : 4 burner by level

o Number of levels : 4 levels

o Primary fuel : Burner Levelo Adaro coal : levels B & C

o Hatillo coal : levels A & D

o Secondary Fuel :

o Pine chips : Level A


4/19

Adaro Hatillo Biomass

Proximate Analysis (As received)

Fixed Carbon (%)Volatil Matter (%)

Moisture (%)

Ash (%)

34.0%36.0%

28.0%

2.0%

44.9%35.3%

14.2%

5.6%

11.5%62.8%

25.4%

0.3%

Ultimate Analysis (Dry basis)

C (%)

H (%)

O (%)N (%)

S (%)

72.7%

4.8%

21.4%0.9%

0.2%

79.0%

5.4%

13.1%1.7%

0.8%

48.9%

6%

44.99%0.1%

0.01%

Properties

LHV (kJ/kg)

Density (kg/m3)

R-R dispersion Factor

R-R mean dia. (mm)

20524

972

0.68 / 1.42

0.09 / 0.15

25623

972

1.09 /1.01

0.11 / 0.09

11190

1.09

0.11

Op. variable / burner level A B C D

Coal flow rate (ton/h)

Biomass flow rate (ton/h)

Primary air flow (ton(/h)Secondary air flow (ton/h)

11.6

2.9

2496.3

14.5

0

2796.3

14.3

0

2496.3

14.5

0

2596.3

Primary air temperature (K)

Secondary air temperature (K)

Walls temperature (K)

Wall internal Emissivity

Gauge Pressure Outlet (Pa)

611

841

373

0.85

-3056

Level A of Burners Biomass + Pulverized Coal


5/19

o Gas-Solid Approach : Eulerian - Lagrangian

o Gas phase : Reynolds Averange Navier-Stokes (RANS)

o Turbulence Model : k-epsilon

o Fuel particle sizes : Rosin-Rammler distribution.

o Devolatilization model : two-competing rates.

o Heterogenous combustion: kinetic/diffussion limited

model.

o Radiation Model : Discrete Ordinates

o Absorption coef.Weighted sum of gray gases model.


6/19

o Gas-Solid Approach : Eulerian - Lagrangian

o Gas phase : Reynolds Averange Navier-Stokes

o Turbulence Model : k-epsilon

o Fuel particle sizes : Rosin-Rammler distribution.

o Devolatilization model : two-competing rates.

o Heterogenous combustion: kinetic/diffussion limited

model.

o Radiation Model : Discrete Ordinates

o Absorption coef.Weighted sum of gray gases model.

Conditions and parameters was presented in the past slide.


7/19

o Model was validated by comparing the simulated concentrations of flue

gas with the experimental available data for operation with coal.

o

Errors are close 1% , 6% and 9% for concentration of O2, CO2and SO2.o The experimental and model CO concentration were found near to zero.

Therefore were difficult to establish a relative error .

10

9

9.4

9.1

CO2 O2

8.4

8.6

8.8

9

9.2

9.4

9.6

9.8

10

10.2

Percentage(%)

Experimental

Model

20

550

0

599

CO SO2

0

100

200

300

400

500

600

700

Concentration[m

g/Nm3] Experimental

Model


8/19

o

The simulation reveals for co-firing case, a decreaseof the zones of burnouts particles compared to

normal operation.

o The major reactivity of the biomass than the coal,

allowing to the biomass particles burning faster than

coal, and collaborating with the coal particleignition.

Co-firing 95% coal5% biomass

Normal Operation100% coal


9/19

o The lower LHV of biomass than coal, provides zones

with lower temperatures than those obtained for

coal operation.

o The maximum temperature achieved is 1820K for

coal combustion and 1710 K for co-firing, leading to

a decrease in the formation of thermal-NOx.

o The mean temperature has slightly decrease < 0,5%.


Tmean = 1460 [K]


Tmean= 1476 [K]


10/19

o The velocity field has not greattly affected by the

inclusion of the biomass into the process,

considering the flame vortex is maintaing far away

from the boiler walls.

o

For the co-firing case, it is observed a reduction inthe flue gas mean velocity at the burner level A

close to 3%, associated to fast combustion of the

biomass particles, near to the burner zone, leading

an increase in the diameter of the flame vortex.


Vmean = 11,3 [m/s]


Vmean= 11,7 [m/s]


11/19

o The mean turbulence intensity for coal combustion is

15.8% and 20.1% for co-firing conditions.

o The values are agree with the turbulence intensity

reported by Baxter et alfor pulverized coal combustion

(10% typical, 30% maximum).

o Tangential distribution of burners generating highlevels of turbulence, optimazing fuel-air mixture and

improving the combustion efficiency.

Baxter L. Ash deposit formation and deposit propertiesA comprehensive

Summary of Reasearch conducted atSandias

Combustion Research Facility. Sandia

Report. SAND2000-8253.

Co-firing 95% coal

5% biomassTImean = 20,1%


TImean= 15,8%


12/19

0.000

0.001

0.002

0.0030.004

0.005

0.006

0.007

0.008

0 4 8 12 16 20 24 28 32 36 40CO

Conc.perp

owerunit

(mg/Nm3M

WT)

Axial Position (m)

CO - Co-firing

CO - Coal comb.

0.60

0.80

1.00

1.20

1.40

1.60

1.80

0 4 8 12 16 20 24 28 32 36 40

SO2Conc.perpowerunit

(mg/Nm3MWT)

Axial Position (m)

SO2 - Co-firing

SO2 - Coal comb.

5.0

6.0

7.0

8.0

9.0

10.0

0 4 8 12 16 20 24 28 32 36 40

Percentageo

fCO2(%)

Axial Position (m)

%CO2 - Co-firing

CO2 - Coal Comb.

600

800

1000

1200

1400

1600

0 4 8 12 16 20 24 28 32 36 40

MeanTemperature(K

)

Axial Position (m)

T - Co-firing

T - Coal Comb.


13/19

0.000

0.001

0.002

0.0030.004

0.005

0.006

0.007

0.008

0 4 8 12 16 20 24 28 32 36 40CO

Conc.perp

owerunit

(mg/Nm3M

WT)

Axial Position (m)

CO - Co-firing

CO - Coal comb.

0.60

0.80

1.00

1.20

1.40

1.60

1.80

0 4 8 12 16 20 24 28 32 36 40


(mg/Nm3MWT)

Axial Position (m)

SO2 - Co-firing

SO2 - Coal comb.

5.0

6.0

7.0

8.0

9.0

10.0

0 4 8 12 16 20 24 28 32 36 40

Percentageo

fCO2(%)

Axial Position (m)

%CO2 - Co-firing

CO2 - Coal Comb.

600

800

1000

1200

1400

1600

0 4 8 12 16 20 24 28 32 36 40

MeanTemperature(K

)

Axial Position (m)

T - Co-firing

T - Coal Comb.


14/19

0.000

0.001

0.002

0.0030.004

0.005

0.006

0.007

0.008

0 4 8 12 16 20 24 28 32 36 40CO

Conc.perp

owerunit

(mg/Nm3M

WT)

Axial Position (m)

CO - Co-firing

CO - Coal comb.

0.60

0.80

1.00

1.20

1.40

1.60

1.80

0 4 8 12 16 20 24 28 32 36 40


(mg/Nm3MWT)

Axial Position (m)

SO2 - Co-firing

SO2 - Coal comb.

5.0

6.0

7.0

8.0

9.0

10.0

0 4 8 12 16 20 24 28 32 36 40

PercentageofCO2(%)

Axial Position (m)

%CO2 - Co-firing

CO2 - Coal Comb.

600

800

1000

1200

1400

1600

0 4 8 12 16 20 24 28 32 36 40

MeanTemperature(K

)

Axial Position (m)

T - Co-firing

T - Coal Comb.


15/19


RHFmean= 165,3 [MW]

100% coal

RHFmean= 166,3 [MW]


THFmean= 198,1 [MW]

100% coal

THFmean= 199,2 [MW]

Total Heat FluxRadiation Heat Flux


16/19

o A CFD model was developed and validated using field concentration of

the flue gas with a low relative error.

o It was found that a 5% mass replacement of coal by feeding biomass into

level A reduces the SO2and O

2concentrations in a 5% and 1.1%

respectively. On the other hand, the concentration of CO is maintained

near zero and CO2(9.4%) is kept similar to the reference condition.

Meanwhile, flue gas mean temperature it decrease by 2% for co-firing

case.

o

The inclusion of biomass into the coal combustion process, presentscomparatives advantages, allowing a decreasing of pollutant emissions

concentrations, without greatly affecting the vorticity, residence time of

the fuel particles, radiate and convective heat flux and flue gas

temperature inside the boiler.


17/19

o E-CL company and his workers for their support in providing key

boundary conditions and measurements validations for the study.

o

FONDEF Project D09I1173 for financial Support of this work.o CONICYT for give me a scholarship support.

o Mechanical Engineering Department of University of Concepcin, for

the possibility to use his computational facilities.

o Technological Development Unit for his financial support and guide.

o Chemical Engineering Department of University of Concepcin for

giving me the opportunity to perform my PhD studies.


18/19

o Pulverized Coal Combustion

o Study the effects to incorporate biomass in others levels of

burners (B,C and D) and other types of biomass, into a

pulverized coal combustion boiler.o We expect the power plant provide experimental data

from his co-firing test at industrial scale.

o Fluidized Bed Combustion

o Develop co-firing experiences with several types of biomass

in a pilot scale Fluidized Bed Combustor to study the effectto incoporate biomass into a pilot scale combustor.

o Study and modelling the ash deposition at pilot scale, using

cfd tools and the develop of co-firing tests into a fluidized

bed combustor.


19/19

Thank You Very much for your attention

Questions?

Dr (c). Ing. Rubn A. Prez J.

[email protected]

Antofagasta, Chile.
mailto:[email protected]:[email protected]

Biomass Replacing in a Pulverized Coal Utility Boiler - Final Version

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