Experimental and modeling assessment of sulfur release from coal under low and high heating rates

Paulo Amaral Debiagi, Coskun Yildiz, Marcel Richter, Jochen Ströhle, Bernd Epple, Tiziano Faravelli, Christian Hasse

Research output: Journal PublicationArticlepeer-review

12 Citations (Scopus)


Coal combustion releases elevated amounts of pollutants to the atmosphere including SOX. During the pyrolysis step, sulfur present in the coal is released to the gas phase as many different chemical species such as H2S, COS, SO2, CS2, thiols and larger tars, also called SOX precursors, as they form SOX during combustion. Understanding the sulfur release process is crucial to the development of reliable kinetic models, which support the design of improved reactors for cleaner coal conversion processes. Sulfur release from two bituminous coals, Colombian hard coal (K1) and American high sulfur coal (U2), were studied in the present work. Low heating rate (LHR) experiments were performed in a thermogravimetric analyzer coupled with mass spectrometry (TG-MS), allowing to track the mass loss and the evolution of many volatile species (CO, CO2, CH4, SO2, H2S, COS, HCl and H2O). High heating rate (HHR) experiments were performed in an entrained flow reactor (drop-tube reactor - DTR), coupled with MS and nondispersive infrared sensor (NDIR). HHR experiments were complemented with CFD simulation of the multidimentional reacting flow field. A kinetic model of coal pyrolysis is employed to reproduce the experiments allowing a comprehensive assessment of the process. The suitability of this model is confirmed for LHR. The combination of HHR experiments with CFD simulations and kinetic modeling revealed the complexity of sulfur chemistry in coal combustion and allowed to better understand of the individual phenomena resulting in the formation of the different SOX precursors. LHR and HHR operating conditions lead to different distribution of sulfur species released, highly-dependent on the gas-phase temperature and residence time. Higher retention of total sulfur in char is observed at LHR (63%) when compared to HHR (37-44%), at 1273 K. These data support the development of reliable models with improved predictability.

Original languageEnglish
Pages (from-to)4053-4061
Number of pages9
JournalProceedings of the Combustion Institute
Issue number3
Publication statusPublished - 2021
Externally publishedYes
Event38th International Symposium on Combustion, 2021 - Adelaide, Australia
Duration: 24 Jan 202129 Jan 2021


  • Coal
  • Kinetic modeling
  • Pyrolysis
  • SO
  • Sulfur

ASJC Scopus subject areas

  • General Chemical Engineering
  • Mechanical Engineering
  • Physical and Theoretical Chemistry


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