Methane gas is liberated during underground coal mining. As a result, mines use extensive ventilation systems to circulate large quantities of air through the mine to keep this gas from building up underground, thereby maintaining safe working conditions. This air is then vented at the surface. Though regulated control of these methane emissions is rarely required, voluntary control of methane, a highly potent greenhouse gas, may produce carbon credits for profit.
Ventilation Air Methane (VAM)
For control of this ventilation air methane (VAM), the Ecopure RTO is the proper Dürr solution as it provides maximum flexibility to coal mine VAM applications. The system requires no supplemental fuel at methane levels of 0.3% or higher, and adjusts operation accordingly to varying levels of methane during VAM exhaust.
The design was created with safety as the first consideration. The RTO operates in a flameless mode, using a burner only for initial system heat-up. All RTO components are intrinsically safe or designed to avoid sparking in the methane-laden airstream. High LEL monitors and sensors with fast reaction time are integral parts of the ventilation safety design, along with fast-acting isolation dampers.
Destruction efficiency of the methane in the RTO is only part of the system’s performance measurement. To maximize this parameter, the proper capture and conveyance of the methane-laden air to the RTO must be accomplished. Dürr’s industrial ventilation design experience, coupled with use of computational flow dynamics (CFD), insure that capture hood and ductwork will minimize capital expense and operational impact on the mine exhaust, while delivering a reliable quantity of methane to the RTO for purification.
Destruction efficiencies in excess of 97% are provided with the Ecopure® RTO system. In addition, high levels of primary energy recovery ensure that the only ongoing utility consumption is from process fan power. A greater return on investment can be achieved with the introduction of secondary heat recovery through the use of Dürr’s Variable Energy Recovery system. Use of this heat for steam, electrical generation or other purposes is possible as a base system design or future add-on.