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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

# $FLOX®$ Combustion at High Pressure With Different Fuel Compositions

[+] Author and Article Information
Rainer Lückerath, Wolfgang Meier

Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, D-70569 Stuttgart, Germany

Manfred Aigner

Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, D-70569 Stuttgart, GermanyRainer.Lueckerath@DLR.de

J. Eng. Gas Turbines Power 130(1), 011505 (Jan 09, 2008) (7 pages) doi:10.1115/1.2749280 History: Received May 03, 2007; Revised May 09, 2007; Published January 09, 2008

## Abstract

In flameless oxidation $(FLOX®)$ the combustion is distributed over a large volume by a high internal flue gas recirculation. This technology has been successfully used for many years in technical furnaces under atmospheric conditions with very low $NOx$ emissions. In the work presented here, $FLOX®$ combustion was for the first time investigated at high pressure in order to assess its applicability for gas turbine combustors. A $FLOX®$ burner was equipped with a combustion chamber with quartz windows and installed into a high pressure test rig with optical access. The burner was operated under typical gas turbine conditions at a pressure of $20bar$ with thermal powers up to $475kW$. Natural gas, as well as mixtures of natural gas and $H2$ were used as fuel. The $NOx$ and $CO$ emissions were recorded for the different operating conditions. $OH*$ chemiluminescence imaging and planar laser-induced fluorescence of $OH$ were applied in order to characterize the flame zone and the relative temperature distributions. The combustion behavior was investigated as a function of equivalence ratio and fuel composition, and the influence of the gas inlet velocity on mixing and emissions was studied. For various operating conditions, the lean extinction limits were determined.

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## Figures

Figure 1

The hexagonal combustion chamber: longitudinal section (left) and cross section with a view of the FLOX® burner with 12 single nozzles (right). The measuring plane of the PLIF experiment is indicated. The three nozzles visible through the window on the detection side are labeled #1 to #3.

Figure 2

Calculated axial velocity and streamline representation of the flow on longitudinal slice through nozzle and combustor axis

Figure 3

Averaged OH PLIF and OH* chemiluminescence images for different inlet velocities. The positions of the nozzles are indicated on the right side of each image. In the PLIF images, only the nozzles #1 and #3 in the measuring plane are shown. Operating conditions for image pairs a∕b∕c∕d:91∕167∕235∕300g∕s air (Tair=588∕669∕706∕714K), 2.6∕4.4∕6.2∕7.7g∕s natural gas, λ=2.0∕2.2∕2.2∕2.3, Tad=1698∕1695∕1712∕1700K, Ptherm=132∕222∕308∕385kW, 50∕1.6∕1.7∕1.4ppmNOx, 2.2∕<1∕<1∕<1ppmCO.

Figure 4

NOx and CO emissions versus Tad for different jet velocities vnozzle. Operating conditions (a/b/c): vnozzle=40∕85∕160m∕s, 91–300g∕s air (Tair=563–733K), 2.0–9.5g∕s natural gas, Ptherm=101–475kW.

Figure 5

NOx and CO emissions versus Tad for different fuel mixtures of natural gas with hydrogen. Operating conditions: vnozzle=86m∕s, 169–192g∕s air (Tair=669–700K), 2.8–6.0g∕s natural gas, 0.0–5.1g∕sH2, Ptherm=168–306kW.

Figure 6

Averaged images of OH PLIF and OH* chemiluminescence for different air equivalence ratios λ. Tad, λ, and the NOx and CO emission values are given for each pair of images. The positions of the nozzles are indicated on the right side of each image. Operating conditions: vnozzle=160m∕s, 300g∕s air (Tair=705–733K), 6.5–9.5g∕s natural gas, Ptherm=323–475kW.

Figure 7

Instantaneous images and corresponding averaged image of the OH* chemiluminescence for λ=2.1 (upper images) and λ=2.6 (lower images). Operating conditions: vnozzle=160m∕s, 300g∕s air (Tair=720∕705K), 8.3∕6.7g∕s natural gas, λ=2.1∕2.6, Tad=1770∕1591K, Ptherm=417∕333kW, 6.3∕<1ppmNOx, <1∕2.2ppmCO.

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