Combustion characteristics of low-concentration coal mine methane in ceramic foam burner with embedded alumina pellets

Dai, Huaming; Lin, Baiquan; Ji, Kaige; Wang, Chaoqun; Li, Qingzhao; Zheng, Yuanzhen; Wang, Ke

doi:10.1016/j.applthermaleng.2015.07.029

Cited by 37 publications

(11 citation statements)

References 52 publications

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“…Meanwhile, at a larger pellet diameter, the radiative heat transfer is stronger, which strengthens the heat transfer to the upstream and downstream from the flame region. For the packed bed, the preheating of fresh gas through the convective heat transfer is more important than that through the radiative heat transfer, because the porosity of packed bed is obviously lower than that of the other porous media (ceramic foam, metal foils, and metal wires). Thus, the fresh gas in the 6 mm pellets is preheated very quickly, and the heat dissipation of the flame region is slow, which make the flame closer to the burner inlet.…”

Section: Resultsmentioning

confidence: 99%

Two-Dimensional Experimental Study of Superadiabatic Combustion in a Packed Bed Burner

Dai

Lin

et al. 2015

Energy Fuels

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ABSTRACT：High-efficiency use of low-concentration coal mine methane is favorable for energy saving and reduction of greenhouse gas emissions. During the porous media combustion, abundant methane at extremely low concentrations will be used not through stable combustion, but through superadiabatic combustion, which transmits flames to the downstream. To directly study the superadiabatic combustion of low-concentration methane, we set two-dimensional (2D) temperature measuring points in the burners, extended the temperature measurements via a radial basis function (RBF) to the whole burner, and plotted a 2D temperature distribution. Then the effects of working conditions, pellet diameter, and burner length on the superadiabatic combustion of lowconcentration methane were investigated. The results show that unstable phenomena such as flame rupture and inclining occurred during the combustion wave propagation in the porous medium. The effects of the heat dissipation through burner walls and the heat dissipation from the outlet on the 2D temperature distribution provide a basis for validation of heat dissipation coefficient in numerical modeling. When the equivalence ratio was 0.35, the increase of flow velocity (from 25 to 45 cm/s) accelerated the propagation velocity of the combustion wave from 0.10 to 0.25 mm/s, but the peak temperature of the flames was almost unchanged (about 1425 K). When the flow velocity of methane was 30 cm/s, the increase of equivalence ratio (from 0.25 to 0.35) reduced the propagation velocity of combustion wave from 0.22 to 0.14 mm/s, and significantly raised the peak temperature of flames from 1125 to 1375 K. With a smaller pellet diameter, the increase of pellet diameter is less favorable for acceleration of combustion wave propagation. When the burner length was prolonged from 20.8 cm and 25.6 cm at 4.8-cm interval, the propagation velocity of combustion waves declined by 11.4% and 7.3%, which shows that the prolonging of length was less favorable for deceleration of combustion wave propagation with a larger burner length.

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Section: Resultsmentioning

confidence: 99%

Two-Dimensional Experimental Study of Superadiabatic Combustion in a Packed Bed Burner

Dai

Lin

et al. 2015

Energy Fuels

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“…It should be noted that the allowed maximum flow velocity of the flow controller was approximately 75 cm/s, which maintained the burner combustion regardless of φ . This phenomenon of higher upper limit was different to those for fuels of biogas, methane, and coal mine methane because of the special structure of unsaturated hydrocarbons (ie, olefins and alkynes). In Figure , as φ > 0.7 for 3‐ and 9‐mm alumina pellets, it presented a state of flashback.…”

Section: Resultsmentioning

confidence: 79%

Fuel-lean VOCs combustion in a porous burner stacked with alumina balls: A case for ethylene combustion

et al. 2018

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Summary A porous burner stacked in turn with 3‐ and 9‐mm alumina pellets was established to perform C2H4 combustion experiments by acquiring the flammable limits, temperature variation characteristics, combustion wave velocity, pollutant emissions, and treatment efficiency. The burner operated well at equivalence ratios within 0.3 to 0.7. Larger alumina pellets widened the burner's lower flammable limit. As the flame propagated downstream, the higher premixed gas flow velocity and larger alumina pellets, the higher combustion wave velocity, whereas the circumstances were opposite as the flame spread upstream. The combustion temperature increased with the equivalence ratio and premixed gas flow velocity. In response to the effect of the alumina pellet dimension, 3‐mm alumina pellets corresponded to higher combustion temperatures, lower CO emissions, and higher treatment efficiency than those less than 9‐mm conditions.

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“…The air and methane mixture was ignited at the burner outlet with the real‐time monitoring of the temperature acquisition system. When the temperatures fluctuated within the range of 1 K/min, the combustion was considered as stabilization 32 . Then, the probe was used to sample the gas and the CO and NO x emissions were analyzed.…”

Section: Methodsmentioning

confidence: 99%

Inhomogeneous packed bed burner for improving the utilization of low‐concentration methane

Qian

Dai

et al. 2022

Env Prog and Sustain Energy

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Homogeneous packed bed was usually assumed in the study of porous media combustion. However, the absolute homogeneous structure was impossible in the actual application. In this article, an experimental system was established to study the inhomogeneity of porous media with different diameters and materials of pellets.The effects on the burner temperature, pollutant emissions and start-up characteristics were investigated. Results indicate that the mixed pellets of the three-diameter and four-diameter combinations improved the flame temperature and moved the flame location to the downstream. The CO emission decreased with the increasing of inlet velocity significantly, but the NO x emission increased. For the mixing of zirconia and alumina pellets, the flame temperature was increased and the flame location was close to the outlet with more zirconia pellets. In addition, an orange submerged flame appeared finally compared with the blue flame during the initial ignition of the gas at the surface.

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Combustion characteristics of low-concentration coal mine methane in ceramic foam burner with embedded alumina pellets

Cited by 37 publications

References 52 publications

Two-Dimensional Experimental Study of Superadiabatic Combustion in a Packed Bed Burner

Two-Dimensional Experimental Study of Superadiabatic Combustion in a Packed Bed Burner

Fuel-lean VOCs combustion in a porous burner stacked with alumina balls: A case for ethylene combustion

Inhomogeneous packed bed burner for improving the utilization of low‐concentration methane

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