Advantages of Catalytic and Thermal Oxidizers Over Regenerative Thermal Oxidizers

HiTemp Tech Corporation Oxidizer Solutions to Control Costs

Industrial air-pollution control systems are commonly used to destroy volatile organic compounds (VOCs), hazardous air pollutants (HAPs) and other combustible contaminants in process exhaust streams. While Regenerative Thermal Oxidizers (RTOs) are widely used for high-volume applications, conventional Thermal Oxidizers (TOs) and Catalytic Oxidizers (CATOXs) can offer important advantages depending on the process conditions.

Catalytic and Thermal Oxidizers vs. RTOs

Catalytic and thermal oxidizers can offer significant advantages over regenerative thermal oxidizers (RTOs) for certain industrial VOC and HAP control applications. Depending on the process, advantages can include lower capital cost, simpler operation, faster startup, reduced maintenance requirements and a smaller equipment footprint.

When is a catalytic oxidizer better than an RTO?

A catalytic oxidizer can be advantageous when lower operating temperatures, reduced fuel consumption and rapid startup are important. Catalytic oxidation allows VOC destruction to occur at substantially lower temperatures than conventional thermal oxidation.

When is a thermal oxidizer better than an RTO?

A recuperative thermal oxidizer can be a practical alternative to an RTO for applications where process conditions favor simpler equipment, rapid startup, smaller footprint or reduced maintenance complexity.

Simpler System Design

One of the primary advantages of conventional thermal and catalytic oxidizers is their relative mechanical simplicity. RTOs typically use multiple ceramic heat-recovery beds, switching valves, dampers and associated controls to repeatedly reverse airflow through the system.

A conventional thermal oxidizer generally uses a combustion chamber with a burner and, where appropriate, a recuperative heat exchanger. Catalytic oxidizers operate similarly but use a catalyst to promote oxidation at a lower temperature. Fewer moving components can simplify operation, troubleshooting and maintenance.

Lower Capital Cost for Smaller Applications

RTOs can be highly efficient when treating large, continuous exhaust streams with relatively low VOC concentrations. However, their ceramic media, large vessels, switching valves, structural requirements and sophisticated controls can result in significant capital costs.

For smaller process streams or intermittent operations, a thermal or catalytic oxidizer may provide the required destruction efficiency with a smaller footprint and lower initial investment. This can make these technologies particularly attractive for batch processes, pilot plants, specialty manufacturing and applications with moderate exhaust volumes.

Faster Start-Up and Greater Operating Flexibility

An RTO contains a substantial mass of ceramic heat-transfer media that must be brought to operating temperature. Conventional thermal and catalytic oxidizers can generally have considerably less thermal mass.

This can provide faster start-up and shutdown cycles, an important advantage for processes that do not operate continuously. A system that reaches operating conditions quickly can reduce both start-up time and the amount of auxiliary fuel consumed before production begins.

Catalytic Oxidizers Operate at Lower Temperatures

Catalytic oxidation offers a particularly important energy advantage. The catalyst reduces the temperature required for VOC oxidation compared with conventional thermal oxidation.

Where the exhaust stream is compatible with the catalyst, lower operating temperatures can reduce burner fuel consumption and associated greenhouse-gas emissions. Lower temperatures can also reduce thermal stresses on equipment and may reduce the formation of thermal NOx.

Catalytic systems are not appropriate for every application, however. Compounds that poison, mask, or foul the catalyst must be carefully evaluated when selecting the technology.

RTOs - Better Suited to Certain High-VOC Applications

RTOs are particularly effective when VOC concentrations are relatively low and the large volume of exhaust gas makes regenerative heat recovery economically attractive. They may be less advantageous when VOC concentrations are higher or fluctuate considerably.

Thermal oxidizers can be designed specifically around the heating value of a concentrated process stream and may incorporate recuperative heat recovery or waste-heat utilization. Depending on the process, the VOCs themselves can provide a meaningful portion of the energy required for oxidation.

Reduced Maintenance Complexity

RTO ceramic beds can accumulate particulate matter, condensable organics, silica, or other process contaminants. This can increase pressure drop, reduce heat-transfer performance and eventually require cleaning or replacement of the media. Switching valves and associated actuators also require inspection and maintenance.

Thermal oxidizers eliminate the regenerative ceramic beds and their flow-reversal system. Catalytic oxidizers also avoid the large regenerative beds, although their catalyst requires periodic inspection and eventual cleaning or replacement.

Smaller Footprint

RTOs can be physically large because of the volume required for multiple ceramic heat-recovery chambers. Thermal and catalytic oxidizers can often be packaged in a more compact configuration, particularly at lower process-flow rates.

For facilities where equipment space, structural loading, or installation access is limited, the smaller footprint can be an important consideration.

Choosing the Appropriate Oxidizer

No single oxidation technology is ideal for every application. RTOs offer excellent thermal efficiency and can be a strong choice for continuous, high-volume, low-concentration VOC streams. Their efficiency, however, comes with additional equipment complexity, thermal mass, footprint and capital cost.

Conventional thermal oxidizerscan provide a simpler and more robust solution for concentrated, variable, or intermittent process streams, while catalytic oxidizers can achieve effective VOC destruction at substantially lower operating temperatures when the contaminants are catalyst compatible.

The best technology should therefore be selected by evaluating airflow, VOC concentration and composition, required destruction efficiency, operating schedule, particulate loading, available space, energy consumption, maintenance requirements and total lifecycle cost rather than thermal efficiency alone.

Why Work with HiTemp Tech Corporation?

HiTemp Tech Corporation has extensive experience designing and supplying custom designed and built thermal processing, waste-to-energy, combustion, gasification, and emissions control systems for industrial applications. Every project begins with a detailed evaluation of the location’s waste stream, energy requirements, regulatory considerations and operational objectives.

Our engineering team works with each client to identify practical solutions to reduce disposal costs, improve energy efficiency, create long-term value and lower operating costs for the system investment.

To learn more about HiTemp Tech Corporation's custom-designed systems, visit us at Catalytic Oxidizer Systems and Thermal Oxidizer Systems.

We also have several informational videos focusing on our custom-designed Waste to Energy Systems.

Contact HiTemp Tech Corporation today to discuss your current situation and explore how our oxidizer systems can solve your emission control needs. Contact HiTemp Tech Corporation.

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