Thermodynamic Assessment of Heat Recovery from a Fluidized-Bed Ventilation Air Methane Abatement Unit

Abstract

Methane, a greenhouse gas, is the second largest contributor to global warming after carbon dioxide and is 25 times more effective at trapping heat in the atmosphere than carbon dioxide. In 2015, fugitive emissions of methane from Australian underground coal mines were reported at 25 million tonnes of carbon dioxide equivalent. Ventilation air methane (VAM) is present in low concentrations (below 1.0 vol %), and its abatement and use as an energy source are a challenge for the coal mining industry. This paper examines the recovery of heat from a fluidized-bed VAM abatement unit and utilization in power generation via the Brayton cycle. The objective of the study was to determine the minimum methane concentration required to maintain autothermal operations and produce sufficient power to operate a fluidized-bed plant without supplementary power or fuel. Four configurations were studied and simulated using Aspen Plus software. For direct heat recovery, the minimum methane concentration increased with an inc...