Abstract
The thermal flow reversal reactor (TFRR) and catalytic flow reversal reactor (CFRR) can utilize the ventilation air methane (VAM) from coal mines effectively. The initial cold feed flow mass distribution uniformity in the monolith oxidation bed, the critical part of both reactors, has a great influence on the stability of methane oxidation process and conversation rate. So the emphases are put on the experimental investigations of the cold flow mechanics in the monolith bed based on a simplified reactor test rig. Firstly, the flow resistance coefficients of the monolith bed were calculated, and then the flow resistance mathematical model was built. It was found that the flow mass distribution uniformity was affected by the pressure drop distribution in the monolith bed, and obviously decreased with increasing inlet velocity. The pressure drop distribution was analyzed through a modified momentum equation. The total pressure loss in the lower header was evidently higher than that in the upper header or monolith bed. Additionally, the local losses at the inlet and outlet of the monolith bed were small, so they could be ignored. Finally, the formula of total pressure losses under different flow conditions was established based on the simplified reactor test rig.
Highlights
Considerable amounts of methane are released into the atmosphere with coal-mine ventilation air (VAM) [1, 2]
The utilization of ventilation air methane (VAM) containing very low methane is difficult owing to the fact that the air volume is large (600000~1000000 m3/h discharged from a single ventilation shaft) and the methane resource is variable in concentration and flow rate
Most of thermal flow reversal reactor (TFRR) or catalytic flow reversal reactor (CFRR) researches are based on numerical simulation and many experimental researches are limited to the investigations of one-dimensional combustion characteristics due to the small-scale reactor test, so there is a real lack of investigations of two-dimensional flow mass distribution and flow pressure loss characteristics of the large cross-sectional structured monolith bed
Summary
Considerable amounts of methane are released into the atmosphere with coal-mine ventilation air (VAM) [1, 2]. To achieve good asymmetry of temperature profiles in the oxidation bed, several aspects of work need to be done, which mainly include uniform cold feed distribution, initial even temperature field before reaction, symmetric reverse flow operation, etc. After many cycles of flow reversal operation, the obvious asymmetry of temperature profiles may occur the stability of methane oxidation reaction process and conversation rate will be seriously affected. Most of TFRR or CFRR researches are based on numerical simulation and many experimental researches are limited to the investigations of one-dimensional combustion characteristics due to the small-scale reactor test, so there is a real lack of investigations of two-dimensional flow mass distribution and flow pressure loss characteristics of the large cross-sectional structured monolith bed. Because the initial cold feed distribution characteristics have important influences on exothermic oxidation reaction, the involved researches in this paper are totally carried out under cold condition and provide the investigation basis for further study of thermal flow mass distribution characteristics in the thermal reacting system
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