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

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 behaviour 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.