A comparison of the influence of fuel/air unmixedness on NOx emissions in lean premixed, non-catalytic and catalytically stabilized combustion

A. Schlegel, M. Streichsbier, R. Mongia, R. Dibble

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Experimental results on the influence of temporal unmixedness on NOx emissions are presented for both non-catalytic and analytically stabilized, lean premised combustion. The test rig used for the experiments consists of a fuel/air mixing section which allows variation of the degree of temporal unmixedness while maintaining a uniform "average over time" concentration profile over the cross section at the inlet to the combustion chamber. The unmixedness is measured as "rms fluctuations in fuel concentration" by an optical probe using laser absorption at 3.39μm over a 9mm gap. "Average over time" measurements are taken with "conventional" suction probe analyzers. The combustion chamber is an insulated, tubular reactor (i.d. 26.4mm). At the inlet to the combustion chamber a honeycomb monolith section is inserted. This monolith is either catalytically active or inactive for catalytically stabilized or non-catalytic combustion respectively. For both modes, the exact same inlet conditions are applied. In catalytically stabilized combustion a fraction of the fuel is consumed within the catalyst and the remaining fuel is burnt in the subsequent homogeneous combustion zone. It is shown that catalytically stabilized combustion yields lower NOx emissions and, more important, that the effect of temporal fuel/air unmixedness on NOx emissions is much smaller than with aon-catalytic combustion under identical inlet conditions. Experimental evidence leads to the conclusion, that the catalyst is capable of reducing temporal fluctuations in fuel concentration and/or temperature in the combustion process, thereby preventing excess NOx formation. As a result, the requirements on mixing quality are less stringent when using catalytically stabilized combustion instead of conventional, non-catalytic combustion.

Original languageEnglish (US)
Title of host publicationCoal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations
PublisherAmerican Society of Mechanical Engineers (ASME)
Volume2
ISBN (Electronic)9780791878699
DOIs
StatePublished - 1997
Externally publishedYes
EventASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition, GT 1997 - Orlando, United States
Duration: Jun 2 1997Jun 5 1997

Other

OtherASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition, GT 1997
CountryUnited States
CityOrlando
Period06/2/9706/5/97

ASJC Scopus subject areas

  • Engineering(all)

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