Development of the DLN Micro-mix Hydrogen...

STAR GLOBAL CONFERENCE

17 March 2015, San Diego (USA)

Development of the DLN Micro-mix Hydrogen

Combustion Technology with STAR-CCM+®

A. Haj Ayed, H.H.-W. Funke, A. Horikawa

Anis Haj Ayed

B&B-AGEMA GmbH, Aachen, Germany

engineering your visions

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Contents

Background: Hydrogen Combustion

Micromix Combustion Technology

Experimental & Numerical Characterization

Micromix Design Exploration with STAR-CCM+

Summary

FH AACHEN UNIVERSITY OF APPLIED SCIENCES


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Background

Background

Use of Hydrogen back in discussion, especially as one alternative for

energy storage

Storage of electricity surplus from renewable sources: Hydrogen

production and re-electrification by fueling stationary gas turbines.

Challenge

Premixing not feasible due to high flammability and flash back risk

High reaction temperatures lead to high NOx emissions

Solution Approach

Development of the Micromix Combustion Technology



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Micromix Hydrogen Combustion Technology

standard one

large flame

several

miniaturized

flamelets



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air

fuel

fuel

fuel



6

0

2

4

6

8

10

12

14

16

18

0,20 0,30 0,40 0,50 0,60

NO

x@

15

% O

2 [

pp

m]

Equivalence Ratio a [-]

exp.: APU H2 030 ED 6.7

Experimental Characterization

Full Load Design Point

≈ 1.3 ppmv

distinct micromix flamelets

Electric Heater



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Development and Manufacturing of DLE Hydrogen Combustor based on the

Micromix burning principle:

micromix flamelets

air flow

Systematic optimization of Hydrogen Micromix burner technology based on Numerical

and Experimental investigations

Integration of optimized Hydrogen burner technology into Gas Turbine applications

Low NOx Hydrogen Combustion ! but, low energy density, large number of

injectors, high manufacturing cost!



8FH AACHEN UNIVERSITY OF APPLIED SCIENCES

Burner Scaling Strategy

D

injector diameterrel. energy

density / injector

D = 0.30 mm 100 %

D = 0.45 mm 225 %

D = 0.55 mm 336 %

D = 0.84 mm 784 %

D = 1.00 mm 1111 %

reference injector size of 0.3 mm increased

gradually to decrease /minimize number of

injectors

gas turbine combustor with

several hundred Hydrogen

injectors


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air inlet

region

Hydrogen

inlet

Hydrogen

injector

AGP gateunstructured mesh, polyhedral cell

type

approx. 1mio volume cells

Numerical Approach – Calculation Domain



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Operational Conditions:

Inlet Temperatures T3: Air: 550 K

Hydrogen: 300 K

Operation Pressure p3: atmospheric (1 bar)

Numerical Methods: STAR-CCM+

- 3D steady RANS

- k,ε turbulence model

- all y+ wall treatment

Combustion Model: - EDC with DARS-CFD

Emission Model: extended Zeldovich NO formation mechanism

Numerical Models and Boundary Conditions



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Micromix Flow Field Characterization


Micromix flamelets stabilized at shear

layer between stabilization vortices

Typical Micromix flame shape confirmed

by numerical simulation in STAR-CCM+


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cold air dilution

lateral cold air penetration

higher vortex temperature

no NO formation inside vortex

NO formation inside vortex


Improvement of 0.3 mm Reference Burner

control of air flow around flame possible

by adjusting air gate width “A”

NOx reduction for higher equivalence

ratios

AB C

D

E

0.3 mm

0.3 mm improved


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Config. A Config. B

axial section

position

adjacent

flames

cold air

penetration

0.45 mm

0.55 mm

0.45 mm 0.55 mm

vortex cooling


Scaling to 0.45 mm and 0.55 mm Injectors

control of air flow around flame and vortex

temperature possible

by adjusting injector distance “E”

Further scaling possible / low NOx maintained

AB C

D

E


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Scaling to 0.84 mm and Further Parametric Improvement

0.3 mm

0.84 mm

0.84 mm

improvedαD

αC > αD

dilution of hot gasH h



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0.3 mm

0.84 mm

0.84 mm

improved

locally increased NO concentration

decreased NO

concentration

Scaling to 0.84 mm and Further Parametric Improvement



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S1 S2 S3 S4 S5 S6 S7 S8axial sections: S9 S10

Scaling to 1 mm Injector Diameter



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0

5

10

15

20

25

0.15 0.25 0.35 0.45 0.55 0.65

NO

/ N

Ox

@ 1

5%

O2

[pp

m]

Equivalence Ratio ФA [-]

0.3 mm - reference

Simulation - 1.0 mm

Experiment - 1.0 mm

0

5

10

15

20

25

0.15 0.25 0.35 0.45 0.55 0.65

NO

/ N

Ox

@ 1

5%

O2

[pp

m]


Scaled --> 0.55 mm

Scaled --> 1.0 mm

0

5

10

15

20

25

0.15 0.25 0.35 0.45 0.55 0.65

NO

/ N

Ox

@ 1

5%

O2

[pp

m]


0.3 mm - improved

Scaled --> 0.45 mm

scaled --> 0.55 mm

0

5

10

15

20

25

0.15 0.25 0.35 0.45 0.55 0.65

NO

/ N

Ox

@ 1

5%

O2

[pp

m]


0.3 mm - reference

0.3 mm - improved


reference burner improvement up-scaling and injector distance improvement

up-scaling and burner height improvement reference vs. status

15 ppm limit

NOx Emissions of Reference and Scaled Burners

6.2 to 1.1 ppm

(nearly 5 times less)

6.2 to 1.6 ppm @

11 times higher

energy density


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Summary

Successful development of Hydrogen DLN Burner with single digit NOx

emission

Numerical design exploration in STAR-CCM+ helped identify how to

control NOx emissions while increasing energy density

Injector number reduced more than 10 times while maintaining low NOx

Possible application in industrial gas turbines


Development of the DLN Micro-mix Hydrogen...

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