montreal
Post on 11-Aug-2015
57 Views
Preview:
TRANSCRIPT
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
2
35
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.
5
35
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.
6
35
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
8
35
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.
9
35
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
10
35
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
11
35
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.
12
35
Combustor arrangement II
Front plates and resulting flames: array configuration (left), andtwo-stage axial configuration (right)
13
35
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
14
35
Burner design (pilot & array burner) II
CBO3 burner module. Left: principles, right: final proportions
15
35
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
16
35
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.
18
35
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
21
35
Automated recognition of the frequencies and amplitudesof interest II
Refined frequency scan around the peak frequency of interest
22
35
Automated recognition of the frequencies and amplitudesof interest III
Sensitivity analysis at the measured frequency
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
25
35
Driver effect of the pilot flame on the main flame I
Set-up: arrayburner, with 4active flames
=⇒
∣
∣
∣
∣
∣
∣
∣
6 5 47 P 3
8 1 2
∣
∣
∣
∣
∣
∣
∣
Average
All dimensions in pixels50 100 150
0
50
100
150
200
250
300
RMS
50 100 1500
50
100
150
200
250
300
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
26
35
Driver effect of the pilot flame on the main flame II
Amplitude @ 200Hz [a.u.]
50 100 1500
50
100
150
200
250
300
0 1 2 3
Phase @ 200Hz [rad]
50 100 1500
50
100
150
200
250
300
−2 0 2
Amplitude and phase maps at the 200hz frequency peak
27
35
Sound amplification by the pilot flame
On-demand flame pulsation at 200Hz,by turning on and off the pilot stage
28
35
Extension of the combustion domain I
Increased operability: comparison between steady and pulse flameat the same inlet mixture condition.
29
35
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.
30
35
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.
31
35
Example of use, towards gas turbine application II
log(Amplitude spectrum Mike 1)T
ime
(s)
Frequency (Hz)500 1000 1500 2000 2500 3000
0
5
10
15
20
25
30
35
40
45
50
Flame noise power spectrum vs. time. No flame out when themain stage suddenly drops in power. The pilot flame is robust.
33
35
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.
34
35
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.
35
35
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
top related