Biothermica - Model Vamox -Ventilation Air Methane (VAM)

The VAMOX® technology provides many advantages and features, including:

• Proven fail-safe design and safety features exceeding MSHA’s requirements to ensure miners’ safety.
• Mechanical connection to the vent shaft designed to prevent any possible impact on the mine’s ventilation capacity while also preventing VAM dilution.
• RTO’s design can be customized using a proven process simulator to optimize the system’s performance over the specific range of VAM flow rate and methane concentration specified.
• Proprietary control strategy, including the auto-adjustment of process parameters based on methane concentration, in order to maximize performance and allow processing VAM with highly variable methane concentration up to 1.2% without experiencing overheat issues.
• Low parasitic power consumption and maintenance costs.
• Designed for facilitated relocation. System built in modular sections that can be easily dismantled and moved within ~2 months to different shafts throughout their service life, as the progression of underground mining activities lead to the commissioning of new ventilation fans.

The VAMOX® converts VAM into carbon dioxide and water vapor using the proven principle of regenerative thermal oxidation (RTO), which has been applied by Biothermica since 1990 through its proprietary BIOTOX® RTO technology on different types of industrial emissions.

The Vamox® operating principle consists in using a series of valves to periodically reverse the airflow through heat exchangers (beds) filled with heat absorbing media. This principle allows retaining within the system enough energy to sustain to oxidation of methane without the need of supplemental energy input (i.e. propane burner), which if forbidden during VAM processing. However, a gas burner located on the combustion chamber is used to preheat the ceramic media (see Figure 1), but this burner must be turned off prior VAM can be introduced in the system.

In a typical operation cycle, two phases take place:

• During the first half of the cycle (Phase I - see Figure 2), dampers (valves) are positioned so that VAM enters the system via bed #1.
• During this phase, the ceramic media within bed #1, which is initially hot, transfers its heat and warms up the incoming VAM. As VAM flows upward through the hot heat exchanger, it reaches the oxidation temperature range. Depending on process conditions, the oxidation may partially or even totally take place within the first heat exchanger.
• Then, the hot gas enters the oxidation chamber, which provides additional residence time to complete oxidation of methane. Then, the hot oxidized gas flows downward through ceramic bed #2, which is “cold” at the beginning of Phase I and recover heat from the gas. The oxidized gas cools down and is then released to the atmosphere.
• As the cycle progresses, bed #1 cools down and bed #2 heats up.
• After a defined half-cycle duration, dampers positions are switched to reverse the flow and Phase II begins (see Figure 3). During this second phase, the role of beds #1 and #2 are reversed.

Through the oxidation cycles, each heat exchanger bed is therefore alternatively used to heat VAM or to recover heat from the hot oxidized gas before it is released to the atmosphere.