A new method for controlling the ignition state of a regenerative combustor using a heat storage device

Abstract

Regenerative oxidizers are very useful for combustion of methane-air lean mixtures (<1% vol. and as low as 0.15%), as those generated in coal mines (ventilation air methane, VAM). However, the performance of the oxidizer is unstable, leading to overheating or extinction, when methane concentration varies. We propose a new procedure for overcoming this problem, using the heat storage concept. Thus, this issue is addressed by proposing the use of an external sensible heat storage system, added to the regenerative oxidizer, capable of storing the excess of heat released in the oxidizer during rich concentration periods, and using it to heat the feed as needed during lean concentration periods. The performance of the heat storage system has been studied by simulating the behavior of a regenerative thermal oxidizer designed to operate at 0.25% vol. nominal feed methane concentration. It was found that the regenerative oxidizer, provided with the heat storage system together with a feedback controller that regulates the heat extracted/introduced in the oxidizers can operate satisfactory, dealing with the variations in methane concentration found in ventilations of coal mines.

Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources

“…As such, COs are not suitable to use in large volume industrial streams with low VOC concentrations. 1166 Taking into account the low initial investment and high flexibility, COs are suitable for treating VOC streams with low flowrate (< 5000 m 3 •h -1 ). However, its important to note that the use of RCO and CO systems may not always be beneficial: (1) the presence of organometallic or inhibiting compounds may reduce catalytic performance; (2) certain compounds such as C2 to C5 paraffins, cannot be easily oxidized effectively at temperatures lower than 430 °C; (3) emissions should be considered when operating with low VOC concentrations and large flowrates.…”

Selective catalytic reduction of NO in a reverse-flow reactor: Modelling and experimental validation

“…A one-dimensional (1D) heterogeneous dynamic model has been found to be satisfactory for reverse-flow reactors in previous works [33,35,36]. In heterogeneous models, fluid and solid are described separately using the corresponding property balances which results in better description of the NH 3 dynamics.…”

Coal mine ventilation air methane combustion in a catalytic reverse flow reactor: Influence of emission humidity

“…Reactor stability is determined by the combination of the heat released by the reaction (given by methane concentration) and switching time; reactor stability increasing for higher methane concentration and lower switching time. Switching times lower than 50 s are not considered, as they cause important by-pass of un-reacted methane (wash-out) as explained in the literature, and mechanical problems (flow reversal valves premature ageing) [10][11][12].…”

“…Under rich feed conditions, the heat released and accumulated in the reactor can overheat the catalyst bed, leading to catalyst thermal deactivation. Such issues have limited the industrial use of this type of reactors, and encouraged research in the development of suitable control systems [12][13][14][15].…”