Andersen, J.

Clausen, Sønnik

Fateev, Alexander

Glarborg, Peter

Jensen, Peter Arendt

Johansen, Joakim Myung

Nielsen, Karsten Lindorff

Tonell, M.

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 21, 2017Local Measurements in Two Full-Scale Swirl Stabilized Bio-Dust BurnersA Parametric StudyJohansen, Joakim Myung; Jensen, Peter Arendt; Clausen, Sønnik; Fateev, Alexander; Nielsen, KarstenLindorff; Tonell, M.; Andersen, J.; Glarborg, PeterPublication date:2014Document VersionPeer reviewed versionLink back to DTU OrbitCitation (APA):Johansen, J. M., Jensen, P. A., Clausen, S., Fateev, A., Nielsen, K. L., Tonell, M., ... Glarborg, P. (2014). LocalMeasurements in Two Full-Scale Swirl Stabilized Bio-Dust Burners: A Parametric Study. Abstract from Jointmeeting of the British and Scandinavian-Nordic Sections of the Combustion Institute, Cambridge, UnitedKingdom.LOCAL MEASUREMENTS IN TWO FULL-SCALE SWIRLSTABILIZED BIO-DUST BURNERS: A PARAMETRIC STUDYJ.M. Johansen1,∗, P.A. Jensen1, S. Clausen1, A. Fateev1, K.L. Nielsen1,M. Tonell2, J. Andersen3 and P. Glarborg11 DTU Chemical Engineering, Soltofts Plads B229, 2800 Kongens Lyngby, Denmark2 Vattenfall, Stberigade 14, 2450 Copenhagen SV, Denmark 3 DONG Energy, Amerikavej 7, 6700 Esbjerg, DenmarkIntroductionIn the strive for at CO2-neutral energy pro-file the exploitation of biomass in central anddecentral heat and power plants has continu-ously increased in recent decades. The fur-ther development of these plants are centralif they are to live up to the demands for fuelflexibility, stable performance, and high ef-ficiency, making thermal plants the arguablybest near-term solution to provide renewableenergy suitable for base load operation.Today the dedicated bio-dust burners canbe grouped into two main categories: 1)burners originally developed for pulverizedcoal combustion and retrofitted to employbiomass fuels and 2) burners purposefullybuild for pulverized biomass fuel, but basedon the experience and data from coal burners.This work presents in-situ measurementsfrom two centralized combined heat andpower plants employing each of the two gen-erations of wall fired, air-staged low NOxbio-dust burner: Amager (AP, 350MWth) andHerning Power Plant (HP, 300MWth). Thus,providing insight into how each of theseflames react to systematic changes in the op-erational conditions.Analytical MethodsThe flames are characterized using bothnon-intrusive high speed optical observationsin the visual (VIS) and the infrared (IR)spectrum as well as intrusive probe measure-ments. As illustrated on Figure 1, flame map-pings are made along the center line enteringthe boiler through the burner. While opticalobservations are acquired from the view portsinstalled at the side (A) and back (B) of theboiler. Solely mapping along the center axisensured fast analysis intervals while still be-∗Corresponding author: jjoha@kt.dtu.dking able to capture key features of the flame.Figure 1: Horizontal cross sectional view of the AmagerPower Plant with the probe fully inserted throughthe center of the burner. View ports used for opti-cal observations are indicated.The analytical methods applied throughthe probe include gas phase temperaturemeasurements using both suction pyrome-try and optical fourier transform infrared(FTIR) spectroscopy. Gas species concen-tration measurements of O2, CO, CO2, H2O,and light hydrocarbons have been quantifiedby temperature controlled extractive gas sam-pling analyzed by parallel IR and ultravi-olet (UV) cells and O2 paramagnetic ana-lyzer. The optival observations in the VIS areprimarily used to characterize flame shape,flame instabilities by e.g. flame lift while thehigh speed IR imaging can be used to trackparticle trajectories and particle cloud surfacetemperatures by two-line pyrometry.Operational ConditionsExtensive studies were carried out oneach power plant compiling a comprehen-sive database of different operating condi-tions together with the corresponding flameresponses. The changes in operational condi-tions include:• Air flows (primary (PA), secondary (SA),tertiary (TA), and combinations herof)• Air flow temperatures (PA, carrier air(CA))• Degree of swirl (SA and TA)• Fuel load• Particle size distributionAll changes to the operational conditionshave been carried out systematically and withlarge variations to ensure statistically signifi-cant flame responses.ResultsInherent differences in the flame charac-teristics have been observed when comparingthe results from the two burners employed inthis study. As seen from Figure 2, the dif-ferent mixing patterns of the two burners re-sult in inverted occurrences of the gas speciesprofiles here illustrated by the CO profile.This inverted behavior recur, as well, in gasphase temperatures and relative penetrationdepth of cold particle clouds.0 1 2 3 4012345[CO] [vol. % (wet)]x = D  [ −] H P  R e f e r e n c e  f l a m e A P  R e f e r e n c e  f l a m eFigure 2: Comparison of the CO profile along the centeraxis of the two burners in reference configuration.x/D being the axial distance, x, normalized by theburner diameter, D.Changes in the burner air flow were foundto influence to the greatest extend on theflame properties, i.e. changes to the degree ofswirl, air-split settings, etc. In general, flowchanges impacting directly on the internalrecirculation zone (IRZ) seem to have highimpact on the observed characteristics. De-creasing the swirl number by approximately20% reduces (> 50%) or in some cases eveneliminates the presence of pyrolysis gases inthe near burner field from maximum quan-tities of 2–3 vol. % CO and 0.2–0.3 vol. %methane and acetylene. Destabilizing theIRZ also lowers the flame temperature in thenear burner field with as much as 200K.Figure 3: Significant visual differences are observed be-tween well attached (upper) and detached (lower)flames.Flame instabilities could easily be ob-served by visual means, as seen in Figure 3.Destabilizing the IRZ caused frequent andsignificant flame lifts and general changesto the flame shape. Such flame instabili-ties where not immediately obvious from thetemperature or chemical species profiels butcould be correlated to the penetration depthof cold particles visualized by imaging in theIR spectrum.ConclusionsThe inherently different mixing patternsin the two flames facilitate direct comparisonof different burners. The coarse flame map-ping has proven to be a successful methodfor making quantitative evaluation of flameresponses to changes in the operating condi-tions. Thus, providing a full set of in-situdata that can be used for large-scale burnerevaluation.AcknowledgementsThe Danish Council for Strategic Re-search is gratefully acknowledged for thefunding. Likewise thanks to DONG Energyand Vattenfall for putting their power plantsat our disposal.

Local Measurements in Two Full-Scale Swirl Stabilized Bio-Dust Burners:A Parametric Study

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Local Measurements in Two Full-Scale Swirl Stabilized Bio-Dust Burners:A Parametric Study

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