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Effects of the inner‐secondary‐air damper opening on flow and combustion in a 600‐MW e down‐fired boiler incorporating multiple‐injection and multiple‐staging
Author(s) -
Song Minhang,
Zeng Lingyan,
Liu Yibo,
Chen Zhichao,
Li Zhengqi,
Li Xiaoguang
Publication year - 2017
Publication title -
asia‐pacific journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.348
H-Index - 35
eISSN - 1932-2143
pISSN - 1932-2135
DOI - 10.1002/apj.2091
Subject(s) - boiler (water heating) , airflow , combustion , fly ash , ignition system , nox , secondary air injection , damper , dimensionless quantity , pulverized coal fired boiler , environmental science , mechanics , chemistry , materials science , waste management , composite material , engineering , structural engineering , mechanical engineering , aerospace engineering , physics , organic chemistry
Effects of adjusting the inner‐secondary‐air damper opening among 100%, 70%, and 50% on the flow, combustion, and NO x emissions of a 600‐MW e down‐fired boiler incorporating multiple‐injection and multiple‐staging technology were investigated. Both 1 : 20‐scale aerodynamic tests and industrial experiments were conducted. The small‐scale tests showed that symmetric flow patterns formed in all cases, and the velocities of boundary and outer secondary air decayed more quickly than the velocity of inner secondary air. As the inner‐secondary‐air damper opening decreased from 100% to 50%, the average dimensionless depth of downward airflow reduced from 0.830 to 0.788 while the horizontal velocity in the recirculation zone increased. Industrial experiments demonstrated that, as the inner‐secondary‐air damper opening decreased from 100% to 50%, the heating rate of fuel‐rich coal/air flow increased from 572 to 687°C/m, the corresponding ignition distance shortened from 1.36 to 1.11 m, and the hopper near‐wall temperature decreased by approximately 50°C. Carbon in fly ash decreased from 7.31% to 6.93%, and NO x emissions rose from 343 to 371 ppm at 6% O 2 . The boiler efficiency improved from 89.78% to 89.92%. An inner‐secondary‐air damper opening of 70% is more reasonable than 50% and 100% considering the ignition distance, carbon in fly ash, and NO x emissions. Copyright © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.