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Regenerative Thermal Oxidation Explained

Thermal oxidation is a means often used to control emissions of Volatile Organic Compounds (VOCs) from process industries. Oxidation of the VOCs occurs when sufficiently high temperature (1,400° F.), adequate residence time, and turbulence are present to break the molecular bonds of any hydrocarbon to ultimately convert the hydrocarbon to carbon dioxide and water. With rare exception, thermal oxidation produces no harmful byproducts nor is there any hazardous waste to treat or dispose of. Though thermal oxidation is a simple process capable of very high VOC destruction efficiency, the fuel consumption and cost to heat the VOC laden process can be severe.

A Regenerative Thermal Oxidizer (RTO) builds on the thermal oxidation operating principals, but at greatly enhanced fuel efficiency. An RTO consists of two or more heat exchangers connected by a common combustion chamber or zone. The heat exchangers consist of beds filled with media which will allow air to pass while serving as a mass to store heat. The media material selection, size, and shape can vary greatly and substantially impact the design and utility efficiency of the RTO.

 RTO Stage 1

 

 RTO Stage 2

The VOC laden air stream enters the first heat exchange bed where the stream passes directly through the media where it is pre-heated en route to the combustion chamber where a burner adds any heat necessary to reach optimum combustion temperature and complete the oxidization process.  

The now clean air stream next enters a second heat exchange bed where the clean stream passes directly through the media where the stream is cooled while simultaneously heating the media before being exhausted to atmosphere.

 
 

 First Stage Oxidization Process
(click image for enlarged version)

 

 Final Stage Before Being Exhausted to Atmosphere
(click image for enlarged version)

The flow through the heat exchange beds is reversed at regular intervals to conserve the heat of combustion within the RTO. Depending on the application, up to 95% of the heat combustion can be recovered and recycled representing a huge fuel savings advantage relative to conventional thermal oxidization.

In comparison to both thermal and catalytic oxidation, Regenerative Thermal Oxidizers (RTOs) have the advantage of the VOC application flexibility and destruction of a thermal oxidizer with better fuel efficiency than a catalytic oxidizer without the risk of poisoning or fouling expensive catalyst.

 

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