Abstract
A thermal flow-reversal reactor is candidate for utilizing low concentration ventilation air methane. In this paper, a numerical study is performed by using the FLUENT software to explore the details of the transient preheating and starting process of the thermal flow-reversal reactor oxidation bed. The bed was heated by hot gas, which was transported and distributed through the holes of manifolds to the middle of the bed. The homogeneous porous media and coupled heat transfer models were chosen; and the mass and heat flow distributions passing through the holes, the heat transfer on the outer surface of the manifold and the temperature distribution of the bed were calculated. The results indicate that the heat of the hot gas passing through the holes decreases gradually along the direction of the hot gas flowing in the manifold, causing the temperature of the bed decrease accordingly. The calculated temperatures of the oxidation bed are compared with the tested results. The maximum error between the calculation and the test was 8.9%.
Highlights
Methane vented from coal mine exhaust shafts constitutes both an unused source of energy and an atmospheric greenhouse gas (GHG), which is 21 times more potent than Carbon Dioxide over a 100-year timeframe in trapping heat in the atmosphere [1,2,3]
The thermal flow-reversal reactor (TFRR) and the catalytic flow-reversal reactor (CFRR) are both candidates for utilizing the low methane concentrations contained in ventilation air methane (VAM) streams [5,6,7,8], and TFRR has been commercially used in Australia and China [9]
The difference of the mass flow distribution of the holes is due to the variable density of the hot gas in the manifold
Summary
Methane vented from coal mine exhaust shafts constitutes both an unused source of energy and an atmospheric greenhouse gas (GHG), which is 21 times more potent than Carbon Dioxide over a 100-year timeframe in trapping heat in the atmosphere [1,2,3]. The thermal flow-reversal reactor (TFRR) and the catalytic flow-reversal reactor (CFRR) are both candidates for utilizing the low methane concentrations contained in VAM streams [5,6,7,8], and TFRR has been commercially used in Australia and China [9]. They employ the flow-reversal principle to transfer the heat of combustion first to a solid medium back to incoming air in order to raise its temperature to the ignition temperature of methane
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