RTO DEFINITION
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 (greater than 1,400°F.), adequate residence time,
and turbulence (the 3 T's) 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 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 transfer and store heat. The media material
selection, size, and shape can vary greatly and substantially impact
the design and utility efficiency of the RTO.
The flow sequence is that the VOC laden air stream enters the first heat exchange bed where the stream passes directly through the media and is preheated en route to the combustion chamber where a burner adds any supplemental heat necessary to reach and maintain optimum combustion temperature and complete the oxidization process.
The flow through the head exchange beds is reversed at regular intervals to retain 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, 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.
