The Recuperative Thermal Oxidizer converts VOCs and HAPs to carbon dioxide and water vapor through high-temperature oxidation. A recuperative heat exchanger (either a plate type or shell-and-tube type) is employed to recover thermal energy from the oxidation process and thereby lower fuel costs. Operating temperatures are around 1,500°F.
While high-temperature-rated metal alloys are used to fabricate the recuperative exchangers, they may still experience thermal failures due to hot spots caused by poor airflow design, to particulate deposits, to corrosion/metal oxidation, or to high VOC concentrations causing extreme auto-ignition heat releases in parts of the exchanger.
Recuperative thermal oxidizers are less expensive than RTOs from a capital cost standpoint because they utilize lower-cost materials, and because they are smaller, using less material. Their design is simpler than an RTO, with fewer moving parts. However, thermal efficiencies can only go as high as 65 percent. Therefore, fuel costs may be as high as six to seven times as much as an RTO.
Despite these limitations, recuperative thermal oxidizers are a good fit for certain applications, and NESTEC has successful TOs operating throughout the USA.