RESEARCH ARTICLE

A combined experimental and theoretical study of micronized coal reburning

  • Hai ZHANG ,
  • Jiaxun LIU ,
  • Jun SHEN ,
  • Xiumin JIANG
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  • Institute of Thermal Energr Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Received date: 15 Oct 2012

Accepted date: 10 Dec 2012

Published date: 05 Mar 2013

Copyright

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg

Abstract

Micronized coal reburning (MCR) can not only reduce carbon in fly ash but also reduce NOx emissions as compared to the conventional coal reburning. However, it has two major kinetic barriers in minimizing NOx emission. The first is the conversion of NO into hydrogen cyanide (HCN) by conjunction with various hydrocarbon fragments. The second is the oxidation of HCN by association with oxygen-containing groups. To elucidate the advantages of MCR, a combination of Diffuse Reflection Fourier Transform Infrared (FTIR) experimental studies with Density Functional Theory (DFT) theoretical calculations is conducted in terms of the second kinetic barrier.

FTIR studies based on Chinese Tiefa coal show that there are five hydroxide groups such as OH-π, OH-N, OH-OR2, self-associated OH and free OH. The hydroxide groups increase as the mean particle size decreases expect for free OH. DFT calculations at the B3LYP/6-31 G(d) level indicate that HCN can be oxidized by hydroxide groups in three paths, HCN+OH→HOCN+H (path 1), HCN+OH→HNCO+H (path 2), and HCN+OH→CN+H2O (path 3). The rate limiting steps for path 1, path 2 and path 3 are IM2→P1+H (170.66 kJ/mol activated energy), IM1→IM3 (231.04 kJ/mol activated energy), and R1+OH→P3+H2O (97.14 kJ/mol activated energy), respectively. The present study of MCR will provide insight into its lower NOx emission and guidance for further studies.

Cite this article

Hai ZHANG , Jiaxun LIU , Jun SHEN , Xiumin JIANG . A combined experimental and theoretical study of micronized coal reburning[J]. Frontiers in Energy, 2013 , 7(1) : 119 -126 . DOI: 10.1007/s11708-012-0226-6

Acknowledgements

This work was supported by Doctoral Fund of Ministry of Education of China (2010), the National Natural Science Foundation of China (Grant No. 50876060) and China Postdoctoral Science Foundation funded project (2012M511091).
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