Metal Decorating & Controlling Your VOC Emissions

The major emission sources in metal can surface coating operations are:

• Coating application lines
• Flash-off areas
• Drying ovens
• Curing ovens

For both new and existing sources, technologies available to achieve the emission standards include:

1. Applying materials (coatings and thinners) that meet the emission limit, either individually or collectively,
2. Using a capture system and add-on control equipment to meet the emission limit, or
3. Using a combination of both approaches.

The most typical add-on control equipment is an oxidation solution to eliminate VOCs emitted from metal decorating applications. Oxidation of VOCs and other air pollutants works by simply oxidizing the air pollutants with oxygen and heat. In this environment the VOCs are converted to harmless inert byproducts like CO2, water vapor (H2O), and usable heat. These harmless by-products are released to the atmosphere or used within primary or secondary energy recovery techniques to further lower the operational costs.

A Regenerative Thermal Oxidizer (RTO) is recognized as the most effective and cost-efficient way to destroy VOCs from these processes. Each Regenerative Thermal Oxidizer (RTO) system incorporates specialized ceramic media in the regenerator (heat transfer bed) to allow thermal efficiencies up to 97%. RTOs operate by preheating the process air as it passes upward through the first ceramic heat exchange media. This pre-heated air then exits the heat exchange media and enters a combustion chamber where it is heated to the setpoint temperature and oxidization of the VOC’s is completed. Hot, clean air is then passed downward through the second ceramic heat exchange media bed where it is cooled. This regeneration of the heat exchanger allows for much higher thermal efficiencies than traditional recuperative style heat exchangers.

Additional control technology such as concentrator systems can be applied to processes generating large volumes of low concentration VOC-laden air prior to sending the process air to the oxidizer such as inside spray machines and flash-off areas. The exhaust air is converted to a smaller volume of highly concentrated gas, resulting in a smaller, less costly oxidizer. Concentrators can also be considered as a method to expand capacity to an existing oxidizer.

To learn more about VOC abatement, click here.

Oxidizer Equipment Solutions