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Comprehensive process design study for layered‐NO X ‐control in a tangentially coal fired boiler
Author(s) -
Zhou Wei,
Moyeda David,
Nguyen Quang,
Payne Roy
Publication year - 2010
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.12004
Subject(s) - boiler (water heating) , combustion , process engineering , coal fired , coal , computational fluid dynamics , engineering , unit operation , mechanical engineering , waste management , chemistry , chemical engineering , aerospace engineering , organic chemistry
As emissions regulations for coal‐fired power plants become stricter worldwide, layering combustion modification and post‐combustion NO X control technologies can be an attractive option for efficient and cost‐effective NO X control in comparison to selective catalytic reduction (SCR) technology. The layered control technology approach designed in this article consists of separate overfire air (SOFA), reburn, and selective noncatalytic reduction (SNCR). The combined system can achieve up to 75% NO X reduction. The work presented in this article successfully applied this technology to NRG Somerset Unit 6, a 120‐MW tangential coal‐fired utility boiler, to reduce NO X emissions to 0.11 lb/MMBtu (130 mg/Nm 3 ), well under the US EPA SIP Call target of 0.15 lb/MMBtu. The article reviews an integrated design study for the layered system at Somerset and evaluates the performance of different layered‐NO X ‐control scenarios including standalone SNCR (baseline), separated overfire air (SOFA) with SNCR, and gas reburn with SNCR. Isothermal physical flow modeling and computational fluid dynamics simulation (CFD) were applied to understand the boiler flow patterns, the combustible distributions and the impact of combustion modifications on boiler operation and SNCR performance. The modeling results were compared with field data for model validation and verification. The study demonstrates that a comprehensive process design using advanced engineering tools is beneficial to the success of a layered low NO X system. © 2009 American Institute of Chemical Engineers AIChE J, 2010