Research Papers: Fuel Combustion

Turbulent Flame Characteristics of Oxycoal MILD Combustion

[+] Author and Article Information
Ruochen Liu, Enke An

Department of Mechanical and
Energy Engineering,
Tongji University,
Shanghai 201804, China

1Corresponding author.

Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF ENERGY RESOURCES TECHNOLOGY. Manuscript received September 8, 2016; final manuscript received June 14, 2017; published online July 17, 2017. Assoc. Editor: Reza Sheikhi.

J. Energy Resour. Technol 139(6), 062206 (Jul 17, 2017) (8 pages) Paper No: JERT-16-1362; doi: 10.1115/1.4037190 History: Received September 08, 2016; Revised June 14, 2017

Oxycoal combustion was numerically simulated in a lab-scale cylindrical furnace (Φ200 mm × 2 m) with high-velocity oxygen jets. The mesoscopic characteristics of turbulent flame behavior such as nondimensional numbers ReT, Ka, and Da were calculated under different jet positions and jet spacing. The results show that for coflow burners, large spacing (L = 75 mm) is not favored due to poor radial mixing and the restriction of wall; except L = 75 mm, as jet spacing increases, the oxidizer flow could be internally diluted to a lower concentration and preheated to a higher temperature, at least 1000 K; for L = 60 mm conditions, the maximum temperature increase is lower than the ignition temperature (437 °C), they are, namely, oxycoal moderate or intense low oxygen dilution (MILD) combustion. For MILD conditions, the mesoscopic parameters of the flame front where temperature gradient is the largest locate in the distributed regime corresponding to l/lF > 1, ReT > 1, Kaδ > 1, and Da < 1, the global regime is depicted as 1 < l/lF < 4, 60 < ReT < 150, 50 < Ka < 500, and Da < 1; for flaming conditions, the regime is depicted as 1 < l/lF < 6, 40 < ReT < 110, 10 < Ka < 800, and Da < 1.

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Fig. 1

The sketch of the lab-scale furnace

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Fig. 2

The total gas emissivity calculated through refined WSGGM and SWBCK

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Fig. 3

The velocity fields of IFRF coal MILD combustion

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Fig. 4

The temperature fields of IFRF coal MILD combustion

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Fig. 5

Mathematical schematic of preheating and mixing zone

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Fig. 6

The contour of flame front under IFRF coal MILD combustion (unit: m)

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Fig. 7

The mesoscopic characteristic parameters of flame front in the regime

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Fig. 8

The distribution of Ka on the X–Z section

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Fig. 9

The distribution of Da on the X–Z section

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Fig. 10

The distribution of l/lF on the X–Z section

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Fig. 11

The specific turbulent flame regime



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