Conifer Systems announces that it has recently been awarded another Aeros MineOx order. This Aeros MineOx solution will include three Regenerative Thermal Oxidizers (RTO) to process Ventilation Air Methane (VAM) and fugitive emission exhausts from an underground coal mine in Western Pennsylvania, USA. Conifer will be providing a turnkey package including equipment fabrication, mechanical/electrical installation, and commissioning.

Conifer’s Aeros MineOx is a specialized type of thermal oxidizer designed to handle VAM and other fugitive emissions produced by many applications but primarily mining.

This project is scheduled to begin installation and commissioning in late Q1 2025.

How does an RTO operate?

Regenerative Thermal Oxidizers abate pollutants through Thermal Oxidation. This works by heating the process stream temperature to a point where the bonds are broken. The methane and VOCs in the process exhaust stream are converted to carbon dioxide, water vapor, and thermal energy.

In an RTO, two heat recovery canisters containing ceramic heat recovery media operate under a “swing bed” absorption principle. The media acts as a heat exchanger for the system. The process gas entering the chamber is heated by the hot (heated on the previous cycle) ceramic media which is subsequently cooled in the process. The process gas then enters the combustion chamber, where most of the oxidation and heat release occurs. The process gas then passes through the other, cooler, bed of ceramic media where the media is heated by the now hot, clean process gas. After a period of time, the beds are reversed as a means of maximizing heat recovery. This reversal is the swing bed principle.

Start-up of an RTO: The RTO unit is brought up to oxidation temperature using supplemental fuel such as natural gas, propane, diesel, or biofuel. During this start-up period, the RTO unit initially purges itself with fresh air and continues to process fresh air until it reaches oxidation temperature equilibrium. The RTO unit is now ready to switch over to process air and begin the thermal oxidation of the process gas with destruction removal efficiency (DRE) per project design.

Normal Operation: The RTO switches from start-up mode running on clean air to operating on process air from the source. To maximize heat recovery, the RTO will automatically cycle or alternate the inlet and outlet heat exchange canisters via a series of pneumatic, hydraulic, or electric valves.

Optimizing Performance: Once methane in process gas reaches oxidation temperatures, provided there is enough methane in the ventilation air, the RTO will enter into an auto thermal mode.

The auto thermal mode is when the RTO is self-sustaining because it is so efficient at reclaiming effluent heat. The units often are capable of sustaining oxidation temperatures without any supplemental fuel utilizing the process stream as the only source of fuel.

Often times the RTO will generate an excess amount of heat. This excess heat that can be utilized by several heat recovery methods including:

• The RTO is self-sustaining because it is so efficient at reclaiming effluent heat, the units often are capable of sustaining oxidation temperatures without any supplemental fuel utilizing the process stream as the only source of fuel
• The RTO generates excess heat that can be utilized by several heat recovery methods including:
  • Waste heat recovery
  • Sending to waste heat boiler for the production of steam and electricity
  • Preheating building air for air conditioning
  • Etc.

What is VAM?

Many underground mines that are rich in gas produce a lot of methane, which can become trapped in the mine shafts with the workers. This methane can create a hazardous and potentially explosive work environment. To reduce the amount of methane in the mine, vents are used to draw the methane out while bringing in fresh air. However, this results in the release of methane into the atmosphere, which is known as Ventilation Air Methane (VAM). Although the concentration of methane in VAM is usually too low to be explosive, it still represents risk and a loss of potential revenue.

To encourage the destruction of methane, rather than venting it into the atmosphere, carbon credit programs have been established in several countries worldwide under different carbon markets such as the California Air Resources Board. These programs incentivize the reduction of methane emissions and have become a mature market.

About Conifer Systems

Conifer Systems designs, manufactures, and installs state-of-the-art emissions control systems and provides aftermarket services to enable industries to meet and exceed their environmental goals. Through reliable environmental solutions, Conifer is committed to clean energy and sustainability.