N-containing pollutant formation in pyrrole counterflow diffusion flames

Combustion and Flame, vol. 276, pp. 114136

Abstract

Biomass conversion through direct combustion (energy production) or pyrolysis (bio-oil production) are novel concepts to reduce CO 2 emission in the energy sector. However, the nitrogen content in biomass feedstocks may result in elevated N-containing pollutants, e.g., NO x , NH 3 , HCN, and nitriles, yet their formation chemistry remains unclear. In this work, we studied N-containing pollutant formation in counterflow diffusion flames fuelled by pyrrole, a biomass tar surrogate component that accounts for the majority of fuel nitrogen. 27 species, including 8 N-containing species, were identified and measured in three flames with designed boundary conditions to reveal the influence of flame temperature and methane addition. Species mole fraction comparisons showed that methane addition and higher flame temperature promoted C 2 –C 6 hydrocarbon formation, but mole fractions of N-containing species did not change much, reflecting less dependence on flame temperature or hydrocarbons in the species pool. An existing kinetic model for pyrrole pyrolysis and combustion was developed by updating the formation reactions of N-containing species based on recent literature studies. Numerical simulations using the kinetic model well reproduced mole fractions of most species except for NO and NO 2 . Model analyses illustrated the nitrogen conversion pathways from pyrrole to individual N-containing pollutant species, and indicated the possible reactions for underestimated mole fractions of NO and NO 2 . This work contributes to a better understanding of the combustion properties of N-containing fuels and N-containing pollutants in the context of biomass energy clean utilization.

Authors 7

1. Bingjie Chen Aachen Institute for Combustion Technology

   Shanghai Jiao Tong University · RWTH Aachen University

   Affiliation as printed

   Institute for Combustion Technology, RWTH Aachen University, Templergraben 64, Aachen 52056, Germany

   Key Laboratory for Power Machinery of M. O. E., Shanghai Jiao Tong University, Shanghai 200240, PR China

2. Sebastian Faller Aachen Institute for Combustion Technology

   RWTH Aachen University

   Affiliation as printed

   Institute for Combustion Technology, RWTH Aachen University, Templergraben 64, Aachen 52056, Germany

3. Luna Pratali Maffei

   Politecnico di Milano

   Affiliation as printed

   CRECK Modeling Lab, Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy

4. Andrea Nobili

   Politecnico di Milano · Stanford University

   Affiliation as printed

   CRECK Modeling Lab, Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy

   Department of Mechanical Engineering, Stanford University, Stanford 94305, CA, United States

5. Matteo Pelucchi corresponding

   Politecnico di Milano

   Affiliation as printed

   CRECK Modeling Lab, Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy

6. Xingcai Lü

   Shanghai Jiao Tong University

   Affiliation as printed

   Key Laboratory for Power Machinery of M. O. E., Shanghai Jiao Tong University, Shanghai 200240, PR China

7. Heinz G. Pitsch Aachen Institute for Combustion Technology

   RWTH Aachen University

   Affiliation as printed

   Institute for Combustion Technology, RWTH Aachen University, Templergraben 64, Aachen 52056, Germany