Thermal Oxidation

Regenerative Thermal Oxidation

Regenerative thermal oxidation (RTO) is a highly efficient process that cleans industrial exhaust by destroying hazardous air pollutants (VOCs and HAPs) and eliminating unpleasant odors. By using internal ceramic heat exchange media, the system traps and recycles its own heat, making the entire purification process incredibly energy efficient.

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Very High Destruction Efficiency

Envanio's RTO systems ensure strict compliance with environmental regulations, delivering a pollutant destruction efficiency of up to 99.8%.

Low Operating Costs

Thanks to optimized regenerative heat recovery, the system achieves a thermal efficiency of up to 97%. By recycling its own heat effectively, it reduces auxiliary fuel consumption and overall operating costs.

Low-Maintenance Design

Envanio’s rugged system engineering reduces maintenance requirements and guarantees reliable, continuous 24/7 operation of the systems.

Process	Thermal Oxidation
Air Flow Rate	1,500 Nm³/h to 360,000 Nm³/h*
Solvent Concentration	up to 10 g/Nm³**
Exhaust Gas Temperature	up to 250 °C
Destruction Efficiency	up to 99.8%
Thermal Efficiency	up to 97%
Energy Sources	Natural gas, propane, butane, fuel oil, gaseous or liquid biofuels, fully electric

Each system is custom-designed based on your requirements and processes.
* Even larger volumes of exhaust air can be cleaned by connecting multiple units in parallel.
** If higher concentrations occur in a given application, fresh air or recirculated gas can be added.

Exhaust Air Intake

The process begins when contaminated, pollutant-heavy exhaust air from industrial production is drawn into the RTO system using a high-powered fan.

Preheating the Exhaust Air

The VOC-laden (volatile organic compound) exhaust air is directed into a ceramic media bed. As the air passes through, it absorbs stored heat from the ceramic blocks, preheating the air to near-combustion temperatures.

Combustion of Pollutants

The preheated air leaves the ceramic bed and enters the combustion chamber. Inside, a natural gas burner maintains the high temperatures required to fully oxidize the VOCs, converting them into harmless carbon dioxide (CO₂) and water vapor H₂O.

Heat Recovery

The freshly purified, scorching-hot air leaves the combustion chamber and is routed through a second ceramic media bed. As the hot air passes through, the ceramic blocks absorb and trap the heat, storing it to be used in the next cycle.

Reversal of Air Flow

Every few minutes, the airflow direction is automatically reversed using either a single rotary valve or a poppet valve system. The previously hot second bed now becomes the preheating bed for the incoming dirty air, while the cooled first bed becomes the new heat recovery bed. This continuous cycling makes the system incredibly energy efficient.

Exhaust of the Purified Air

Finally, the cooled, purified air is safely released into the atmosphere through an exhaust valve and a chimney stack.

To ensure seamless integration into your manufacturing process, Envanio’s RTO systems are available in a variety of customizable models and configurations. Because every industrial facility faces unique air pollutions control challenges, we custom-engineer our units to fit your exact application.

Envanio designs and manufactures highly adaptable RTO systems custom-engineered to meet the strict emission-control demands of your facility’s production processes. Thanks to their versatile, energy-efficient design, our systems are widely utilized across a diverse range of industrial sectors.

Take advantage of our 360° support for air pollution control systems from Envanio or third-party manufacturers. Our service teams support your plant throughout the entire equipment lifecycle, providing routine inspections, preventative maintenance, system audits, efficiency retrofits, repairs, and genuine replacement parts.

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RTO systems offer exceptionally high pollutant destruction efficiency (up to >99%), low operating costs via advanced heat recovery, and a robust design capable of handling a wide range of exhaust air compositions. They are exceptionally cost-effective for high-volume, low-concentration airstreams.

RTO systems are primary choices for removing volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). Typical applications include treating solvents, hydrocarbons, and process emissions from painting, printing, and chemical operations. At high temperatures, these substances are reliably oxidized into carbon dioxide and water vapor. RTOs are also highly effective at destroying odorous compounds (such as aldehydes, ketones, organic acids, and terpenes) as well as hazardous organic pollutants like benzene, formaldehyde, and styrene.

The heat released during combustion is captured and stored within internal ceramic heat media beds. As incoming cold exhaust air enters the system, it passes through these pre-heated beds, absorbing up to 97% of the required thermal energy. This drastic reduction in auxiliary fuel consumption ensures maximum operational efficiency.

An RTO operates in autothermal (self-sustaining) mode when the concentration of pollutants (primarily VOCs) in the exhaust stream provides enough thermal energy to maintain the required oxidation temperature. In this state, the system runs entirely on the energy of the pollutants themselves, eliminating the need for auxiliary fuel.

Modern RTO systems are highly resistant to fluctuating process conditions. During periods of low VOC concentration, an auxiliary burner activates to maintain optimal temperature. At higher VOC concentrations, the system transitions to autothermal (self-sustaining without additional energy) operation. Advanced control strategies, including bypass control, and adaptive temperature logic, spontaneously stabilize the system against extreme peak loads.

Emissions during valve switching are virtually eliminated using purge air systems. This process uses a partial flow of purified air to displace any remaining raw gas from the ceramic media bed before it can escape. These optimized designs guarantee minimal residual emissions, satisfying the most stringent global compliance limits.

To deliver solutions tailored to your specific requirements and varying operating conditions, Envanio offers a wide range of standard and custom-engineered air pollution control systems based on thermal oxidation.

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Electric Regenerative Thermal Oxidation

Envanio's electrically heated regenerative thermal oxidizer (eRTO) combines high VOC destruction efficiency, operational reliability, and exceptional energy performance. By using electric heating elements instead of gas-fired burners, the system avoids combustion-related byproducts and significantly reduces NOₓ emissions. The result is a cleaner, more sustainable solution for industrial air pollution control.

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Recuperative Thermal Oxidation

Recuperative thermal oxidation is a highly efficient process that cleans industrial exhaust air by destroying hazardous air pollutants (VOCs and HAPs) and eliminating unpleasant odors. The system is also well suited for processes where particulate matter and aerosols are generated. An integrated metallic shell-and-tube heat exchanger enables efficient primary heat recovery.

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Direct Fired Thermal Oxidation

Direct fired thermal oxidation is a highly efficient process that cleans industrial exhaust by destroying hazardous air pollutants (VOCs and HAPs) and eliminating unpleasant odors. The system is particularly well-suited when heavily contaminated exhaust streams must be treated reliably with high removal efficiencies, and when complex heat recovery systems are not economically feasible.

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Activated Carbon Adsorption

Envanio’s activated carbon adsorption is based on the physical adsorption process to purify industrial process air of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) from industrial exhaust air, with the option for solvent recovery. In our regenerative systems, both the adsorbent and solvents are recovered for reuse, while in non-regenerative systems, the spent activated carbon is safely disposed of or replaced along with the captured pollutants.

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VOC Concentration

Envanio’s VOC concentration process uses adsorption to concentrate dilute solvent emissions. For cost-effective air pollution control, adsorption is recommended first to concentrate large exhaust airflows with low pollutant loads. The concentrated exhaust air is then routed to downstream recuperative or regenerative thermal oxidation for highly energy-efficient destruction.

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Catalytic Hot Gas Filtration

Envanio’s catalytic hot gas filtration is based on an integrated 3-in-1 process for industrial hot gas and exhaust air purification. Rigid, high-temperature ceramic filter elements enable the simultaneous removal of particulate dust, heavy metals, sulfur oxides (SOx), and nitrogen oxides (NOx) from process exhaust in a single compact system.

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Wet Scrubbing

Envanio’s wet scrubbers rely on absorption for the wet separation of inorganic compounds, particulates, mist, and acidic gases. During the regenerative or direct-fired thermal oxidation of halogenated hydrocarbons or sulfur compounds, substances such as hydrogen halides or SOx are generated, which must be scrubbed from the exhaust air in a downstream wet scrubber.

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Liquid Distillation

Envanio’s distillation systems efficiently separate solvents from water and split complex solvent mixtures into reusable components. Integrated recovery processes reduce raw material consumption and operating costs, with flexible designs for batch or continuous operation.

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Please contact us directly to schedule a personal consultation or submit your project details using our contact form to receive a complementary, no-obligation quote.

Kai Weber

Director Sales EMEA

+49 7142 7863-999 sales@envanio.com

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