Numerical investigation of coal particle stream ignition in oxy-atmosphere

S. Farazi, J. Hinrichs, M. Davidovic, M. Falkenstein T. Bode, S. Kang, A. Attili, H. Pitsch

Research output: Contribution to journalArticlepeer-review

Abstract

The ignition of a stream of coal particles under oxy-fuel atmosphere is studied numerically in a laminar flow. Devolatilization of coal particles is modeled with the chemical percolation devolatilization (CPD) method coupled with a detailed chemistry model for homogeneous reactions. The particle and gas phase interactions are modeled with a fully coupled Euler-Lagrange code. A parametric study is performed to investigate the influence of particle number density, gas temperature, and velocity on ignition. We found that increasing particle number density delays the onset of ignition. Delayed ignition in denser streams is due to the lower gas temperature, which is caused by the higher energy required for particle heating. In addition, increasing particle number density leads to a more continuous and narrower flame front. Particle heating and ignition induce velocity variations in the gas phase through the coupling with particles. In the denser stream, velocity variations become significant and compromise the validity of a constant velocity assumption that is usually made in computing ignition delay time from the observed ignition location. It is also found that high particle slip velocities lead to a locally low volatile concentration and low temperature, and consequently increase ignition delay time.
Original languageUndefined/Unknown
Pages (from-to)477-487
Number of pages11
JournalFuel
Volume241
Early online date19 Dec 2018
DOIs
Publication statusPublished - 1 Apr 2019

Keywords

  • Coal particle stream
  • Ignition
  • CPD
  • Oxy-fuel combustion

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