Using oxygen enrichment and coal fines to diminish NOx emissions from pulverized coal axial diffusion flames

Gregory E. Ogden, Jost O.L. Wendt

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Oxy-fuel combustion of pulverized coal provides additional degrees of freedom that can be used to control flame stability and minimize NOx emissions. One such degree of freedom is the partial pressure of oxygen, PO 2, in the transporting fluid, which would normally consist of recycled flue gas. This paper presents results of research directed at controlling flame aerodynamics through adjustment of this quantity, and through other techniques, to enhance coal ignition, and thereby promote flame attachment and reduce NOx formation. A systematic evaluation of near-flame aerodynamics of axial diffusion flames was conducted. The purpose was to determine how burner operating parameters and oxygen partial pressure influence flame attachment and coal ignition, two properties essential for proper low NOx burner operation. To this end, a novel down-fired laboratory furnace was designed and validated. The equipment consisted of an externally heated, 17kW (thermal) furnace and axial burner both of which are described in detail. Transport "air" oxygen partial pressure (Po2), coal particle size distribution, primary and secondary jet velocity, and wall temperature were varied independently to determine the effect of each variable on flame attachment and NOx. Transport "air" oxygen partial pressure could be controlled to produce transport "air" oxygen concentrations between 13 and 29%. NOx emissions from the furnace when firing a volatile Utah coal were similar to those from fullscale tangentially-fired boilers. The tendency for flame attachment increased with Po2, and coal fines. Increasing Po2 reduced NOx by over 50% by promoting flame attachment. However, in the absence of creating flame attachment, neither oxygen enrichment nor increasing fines had great impact on NOx . The key result to be learned from this work is that oxygen enrichment not only can lower flue gas flow rates for CO2 sequestration, but, if applied intelligently to promote flame attachment, can also decrease "volatile" NO emissions from pulverized coal.

Original languageEnglish (US)
Title of host publication22nd Annual International Pittsburgh Coal Conference 2005, PCC 2005
Pages858-869
Number of pages12
StatePublished - Dec 1 2005
Event22nd Annual International Pittsburgh Coal Conference 2005, PCC 2005 - Pittsburgh, PA, United States
Duration: Sep 12 2005Sep 15 2005

Publication series

Name22nd Annual International Pittsburgh Coal Conference 2005, PCC 2005
Volume1

Other

Other22nd Annual International Pittsburgh Coal Conference 2005, PCC 2005
CountryUnited States
CityPittsburgh, PA
Period9/12/059/15/05

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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  • Cite this

    Ogden, G. E., & Wendt, J. O. L. (2005). Using oxygen enrichment and coal fines to diminish NOx emissions from pulverized coal axial diffusion flames. In 22nd Annual International Pittsburgh Coal Conference 2005, PCC 2005 (pp. 858-869). (22nd Annual International Pittsburgh Coal Conference 2005, PCC 2005; Vol. 1).