Numerical simulations on the self-heating behaviours of coal piles considering aging effect

Hemeng Zhang, K. Sasaki, Xiaoming Zhang, Yuichi Sugai, Yongjun Wang

Research output: Contribution to journalArticle

Abstract

In this study, the theoretical approach and numerical modelling of coal spontaneous combustion were investigated considering the aging effect. Numerical simulations ofthree-dimensional coal piles in cubic wire-mesh baskets (WMBs) were performed using ANSYS FLUENT. A theoretical heat generation model was constructed that incorporated aging effect (using a decay-power factor, γ ), equivalent oxidation exposure time (EOE-time) theory, and moisture evaporation. The results from this model were compared with those obtained from the conventional Arrhenius equation, which does not take aging effect into account. The γ value required to accurately express the aging effect in conjunction with EOE-time theory was determined to be 4 × 10−5 s−1 for the low-rank coal used in this work. This value was obtained by comparing simulated and measured coal temperature-time curves in WMBs. A moisture evaporation model that included an estimated evaporation heat rate was applied, based on the difference between coal moisture ratio and air relative humidity. These models were employed to simulate the self-ignition behaviour of coal piles and to explore the different heating processes of wet and dry coals. Finally, the relationships between pile volume and both critical self-ignition temperature and critical lead time were presented for industrial management of coal piles.
Original languageEnglish
Pages (from-to)1169-1190
Number of pages22
JournalCombustion Theory and Modelling
Volume23
Issue number6
DOIs
Publication statusPublished - Jul 24 2019

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Coal
piles
coal
Piles
Heating
Moisture
Aging of materials
Evaporation
Numerical Simulation
heating
Computer simulation
Ignition
Oxidation
spontaneous combustion
simulation
Heat
Mesh
moisture
wire cloth
baskets

All Science Journal Classification (ASJC) codes

  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology

Cite this

Numerical simulations on the self-heating behaviours of coal piles considering aging effect. / Zhang, Hemeng; Sasaki, K.; Zhang, Xiaoming; Sugai, Yuichi; Wang, Yongjun.

In: Combustion Theory and Modelling, Vol. 23, No. 6, 24.07.2019, p. 1169-1190.

Research output: Contribution to journalArticle

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AB - In this study, the theoretical approach and numerical modelling of coal spontaneous combustion were investigated considering the aging effect. Numerical simulations ofthree-dimensional coal piles in cubic wire-mesh baskets (WMBs) were performed using ANSYS FLUENT. A theoretical heat generation model was constructed that incorporated aging effect (using a decay-power factor, γ ), equivalent oxidation exposure time (EOE-time) theory, and moisture evaporation. The results from this model were compared with those obtained from the conventional Arrhenius equation, which does not take aging effect into account. The γ value required to accurately express the aging effect in conjunction with EOE-time theory was determined to be 4 × 10−5 s−1 for the low-rank coal used in this work. This value was obtained by comparing simulated and measured coal temperature-time curves in WMBs. A moisture evaporation model that included an estimated evaporation heat rate was applied, based on the difference between coal moisture ratio and air relative humidity. These models were employed to simulate the self-ignition behaviour of coal piles and to explore the different heating processes of wet and dry coals. Finally, the relationships between pile volume and both critical self-ignition temperature and critical lead time were presented for industrial management of coal piles.

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