Estimation of NOx emissions from coal-fired utility boilers

Abstract CFD-based engineering models can be cost-effective tools in determining technical feasibility of clean coal-fired power generation technologies like NO x mitigation strategies targeting the reduction of acid rain and smog. Their actual effectiveness depends on their capability to provide realistic engineering estimates without arbitrary adjustment of model parameters. This investigation focused on testing a CFD based NO x model over a variety of coal type, firing configuration and boiler size ranging from 200 MW e sub-critical to most modern 1000 MW e ultra supercritical. In most cases, the NO x estimates based on input data readily available from power plants were found within the range of measured data (with the worst estimate being 22% higher than the maximum measured NO x level). The CFD results also indicated some sensitivity of the NO x estimates to the ratio of volatile nitrogen to char nitrogen and the importance of NO reduction by char. However, this study showed that the locations of fuel-bound nitrogen evolution with respect to the stoichiometric condition within the boiler actually governed the overall NO emissions.

[1]  Mohamed Pourkashanian,et al.  A review of NOx formation and reduction mechanisms in combustion systems, with particular reference to coal , 1997 .

[2]  S. C. Hill,et al.  Modeling of nitrogen oxides formation and destruction in combustion systems , 2000 .

[3]  Luis I. Díez,et al.  Numerical investigation of NOx emissions from a tangentially-fired utility boiler under conventional and overfire air operation , 2008 .

[4]  A. M. Eaton,et al.  Components, formulations, solutions, evaluation, and application of comprehensive combustion models , 1999 .

[5]  Francisco Cadavid,et al.  Coal combustion modelling of large power plant, for NOx abatement , 2007 .

[6]  M. Kaess,et al.  Experimental and Numerical Investigation of NOx Formation and its Basic Interdependences on Pulverized Coal Flame Characteristics , 1993 .

[7]  Mohamed Pourkashanian,et al.  Modelling NOx formation in coal particle combustion at high temperature: an investigation of the devolatilisation kinetic factors , 1999 .

[8]  Lin Ma,et al.  Prediction of unburned carbon and NOx in a tangentially fired power station using single coals and blends , 2005 .

[9]  Roman Weber,et al.  Mathematical Modeling of a 2.4 MW Swirling Pulverized Coal Flame , 1997 .

[10]  S. Visona,et al.  Modeling nitric oxide formation in a drop tube furnace burning pulverized coal , 1999 .

[11]  Brian Stanmore,et al.  Modeling NOx release from a single coal particle I. Formation of NO from volatile nitrogen , 1996 .

[12]  B. R. Stanmore,et al.  3-D modelling of NOx formation in a 275 MW utility boiler , 1996 .

[13]  Adel F. Sarofim,et al.  NO/char reactions at pulverized coal flame conditions , 1981 .

[14]  R. Millares,et al.  Mathematical modelling of fuel NO emissions from PF burners. , 1992 .

[15]  James A. Miller,et al.  Mechanism and modeling of nitrogen chemistry in combustion , 1989 .

[16]  Mohamed Pourkashanian,et al.  Modelling of coal combustion in low-NOx p.f. flames , 1994 .

[17]  E. H. Chui,et al.  Validation of NOx and NOx Precursor Predictions in Coal Flames , 1996 .

[18]  Jean-Luc Harion,et al.  Investigation of the flow, combustion, heat-transfer and emissions from a 609MW utility tangentially fired pulverized-coal boiler , 2002 .

[19]  David W. Pershing,et al.  Char nitrogen conversion: implications to emissions from coal-fired utility boilers , 2000 .

[20]  W. Fiveland,et al.  Use of numerical modeling in the design of a low-NOx burner for utility boilers , 1993 .

[21]  J. L. T. Azevedo,et al.  3-D numerical model for predicting NOx emissions from an industrial pulverized coal combustor , 1994 .

[22]  A. Jensen,et al.  Fuel nitrogen conversion in solid fuel fired systems , 2003 .

[23]  Peter Glarborg,et al.  Influence of process parameters on nitrogen oxide formation in pulverized coal burners , 1997 .

[24]  F. Lockwood,et al.  NOx formation and reduction mechanisms in pulverized coal flames , 1994 .

[25]  Jost O.L. Wendt,et al.  Fundamental coal combustion mechanisms and pollutant formation in furnaces , 1980 .

[26]  S. Visona,et al.  Prediction of NO emissions from a number of coal-fired power station boilers , 2000 .