Advanced Combustion Management

Optimisation of support fuel consumptionburning low heat value gas using controlled

combustion oscillationsGT2015-42377

Dr. Fabrice Giuliani

ASME Turbo Expo 2015Chapter Coal, Biomass & Alternative Fuels

Session Alternative Gaseous FuelsThursday June the 18th, 8:00 AM, Room 510A, ThA-3-4

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Co-authors and background

Vanessa Moosbrugger, Markus Stuetz, Thomas Leitgeb-Simandl

The programme MethaNull is supported by the JITU-PreSeedGrant (Contract P1302031-PSI01) of the Austrian Federal Ministryfor Economy, Family and Youth under guidance of the AustriaWirtschaftsservice GmbH.

Contents

1 Introduction

2 Technical aspects

3 Flame sound control

4 Combustion tests

5 Conclusions

Contents

1 Introduction

2 Technical aspects

3 Flame sound control

4 Combustion tests

5 Conclusions

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Motivation

Methane emissions:

ranked second to carbon dioxide in terms of radiative forcing

atmospheric concentration + 150% compared to pre-industrialtimes

global warming potential 28 times greater than that of CO2

(IPCC, 5th assessment, 2013 [1])

Since 2008, methane emissions inAustrian landfills areforbidden.Disposing of (flaring) landfill

gas with a pilot burner has become asignificant cost factor.

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Incentives of MethaNull

CBOne was called to work on the disposal of very diluted methaneat a lower cost than conventional methods.This technical solution could be extended to the combustion ofother gases with low heat contents.A solution is offered based on controlled acoustic modulation ofcombustion.

This is the MethaNull programme (to approach zero methane gasemissions).

Contents

1 Introduction

2 Technical aspectsThe MethaNull technologyThe siren pulsator

3 Flame sound control

4 Combustion tests

5 Conclusions

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Inspiration: pulse combustion

Thermoacoustic coupling

When undesired → combustion instability.

When desired → pulse combustion.

Benefits of pulse combustion

”Increased rates of heat, mass, and momentum transport duringunsteady combustion hold the key to providing significantimprovements in the performance of many practical combustionsystems”

(Zinn et al., CST 1993, [2])

However pulse combustion has not yet met with success in itsconventional form.

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CBOne’s idea is an ON/OFF pulse combustion concept I

A concept with forcedflame modulation ispreferred to aself-oscillating device.

The pilot flame isused as a pulsationdriver (or shaker).

Operation at differentfrequencies fordifferent loads ismade possible.

The device operatesconventionally for therest of the time.

MethaNull Burner Concept

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CBOne’s idea is an ON/OFF pulse combustion concept II

Operation modes: use the pilotflame as a pulsation driver

The desired effect are:

a better mixing of thereactants

a periodic deformation ofthe flame front that reducesits volume, thus augmentingthe energy density

a dynamic return of hotgases upstream

higher rates of reaction takeplace because the reactantsincoming periodicallycombine acceleration andslight compression

reduce dirt agglomerationbecause of the shaking

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Combustor arrangement I

Assembly = plenum,combustor casing andexhaust

Robust design, builthead-up

Optical accesses andmeasurement ports atdifferent locations

Possibility to operateat free jet andconfined jet condition

The burner operatesat ambientconditions.

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Combustor arrangement II

Front plates and resulting flames: array configuration (left), andtwo-stage axial configuration (right)

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Burner design (pilot & array burner) I

Prerequisites

premixed burner with forceddraft air flow

safety: must operatewithout flash-back inself-aspiration mode

other features: Low pressureloss. Large passages for lowrisk of plugging. Acoustictransparency. Robustness.Low cost.

Solution

start-up from a bunsen-likeconfiguration

extend the operation rangeusing a detached flame

make this possible with aswirl-stabilised flame

favour a low swirl number toavoid to flash-back, the pilotburner was accordinglydesigned with a low swirlnumber

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Burner design (pilot & array burner) II

CBO3 burner module. Left: principles, right: final proportions

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Pulsator I

Basic acoustic experiments performed with wall-mountedloudspeakers

Full-scale operation

An air flow siren pulsator designed by CBOne is used

Compact device that emits a powerful sound that emergesfrom the machinery noise

Robustness: designed to operate under heavy flow conditions

Elevated pressure and temperature conditions

with aggressive or dirty gases

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Pulsator II

F. Giuliani, A. Lang, K. Johannes Gradl, P. Siebenhofer, and J. Fritzer.Air flow modulation for refined control of the combustion dynamics usinga novel actuator.

Journal of Engineering for Gas Turbines and Power, 134(2), 2012.

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Pulsator III

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Pulsator IV

F. Giuliani, P. Gajan, O. Diers and M. Ledoux.Influence of pulsed entries on a spray generated by an airblast injectiondevice

Proceedings of the Combustion Institute, Volume 29, 2002.

Contents

1 Introduction

2 Technical aspects

3 Flame sound controlFrequencies and amplitudes of interestAutomated recognition

4 Combustion tests

5 Conclusions

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Automated recognition of the frequencies and amplitudesof interest I

Global frequency scan

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Automated recognition of the frequencies and amplitudesof interest II

Refined frequency scan around the peak frequency of interest

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Automated recognition of the frequencies and amplitudesof interest III

Sensitivity analysis at the measured frequency

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Flame sound control

Contents

1 Introduction

2 Technical aspects

3 Flame sound control

4 Combustion testsDriver effect of the pilot flame on the main flameSound amplification by the pilot flameExtension of the combustion domainExample of use, towards gas turbine application

5 Conclusions

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Driver effect of the pilot flame on the main flame I

Set-up: arrayburner, with 4active flames

=⇒

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6 5 47 P 3

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Average

All dimensions in pixels50 100 150

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RMS

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Pilot flame

Aligned flames 1−2

Flame 3

Front plate

Flame-flame interaction, between the pilot flame and the 3 cornerflames of the array configuration

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Driver effect of the pilot flame on the main flame II

Amplitude @ 200Hz [a.u.]

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0 1 2 3

Phase @ 200Hz [rad]

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Amplitude and phase maps at the 200hz frequency peak

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Sound amplification by the pilot flame

On-demand flame pulsation at 200Hz,by turning on and off the pilot stage

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Extension of the combustion domain I

Increased operability: comparison between steady and pulse flameat the same inlet mixture condition.

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Extension of the combustion domain II

Increased operability: difference in pilot fuel consumption at thelean blow out limit at steady and at pulsed conditions. Left: freejet. Right: confined jet.

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Example of use, towards gas turbine application I

Pilot only Pilot + Main

Alternate feed of very diluted fuel in the main zone, with the pilotflame excited constantly at 580Hz: flame aspects.

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Example of use, towards gas turbine application II

log(Amplitude spectrum Mike 1)T

ime

(s)

Frequency (Hz)500 1000 1500 2000 2500 3000

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Flame noise power spectrum vs. time. No flame out when themain stage suddenly drops in power. The pilot flame is robust.

Contents

1 Introduction

2 Technical aspects

3 Flame sound control

4 Combustion tests

5 Conclusions

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Conclusions

A device for combusting LHV gases using less support fuelthan conventional methods was presented.

The acoustic energy implied in the process is low. The pilotflame works as an amplifier and driver of the process. Theprocess can be turned on and off on-demand.

The pulsation extends the combustion domain when the fuelcontents of the pilot are reduced.

Figures show up to -10% fuel consumption at design point vs.conventional operation.

Fitted in a gas turbine burning LHV with conventional

fuel support, a more economic operation can be

achieved using this technology.

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References

Thomas F Stocker, Dahe Qin, Gian-Kasper Plattner,M Tignor, Simon K Allen, Judith Boschung, Alexander Nauels,Yu Xia, Vincent Bex, and Pauline M Midgley.Climate change 2013: The physical science basis.Technical report, 2013.1535 pp.

C. R. Stewart, P. M. Lemieux, and B. T. Zinn.Application of pulse combustion to solid and hazardous wasteincineration.Combustion Science and Technology, 94(1-6):427–446, 1993.

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Thank you for your attention!

Optimisation of support fuel consumption burning lowheat value gas using controlled combustion oscillations

Fabrice Giuliani, Vanessa Moosbrugger, Markus Stuetz,Thomas Leitgeb-Simandl

Paper GT2015-42377

Combustion Bay One e.U.

Advanced Combustion ManagementPlueddemanngasse 398010 Graz, Austria

www.CBOne.at