Thermal recuperative oxidizers are less commonly used than direct fired thermal oxidizers or regenerative thermal oxidizers, but are a natural evolution of the direct fired thermal oxidizer by adding primary and/or secondary heat recovery to the setup. They run cooler than RTOs, at about 760° C or 1400° F and have a much lower heat recovery efficiency, up to 80%. But they also tend to have a higher VOC destruction efficiency of 99.99% when compared to an RTO that can only produce a 99% destruction efficiency even in the best of conditions.
Adding a heat recovery system to an oxidation process can greatly reduce the amount of natural gas used within the process and result in a tremendous savings in energy costs. There are two types of heat recovery used by thermal recuperative oxidizers.
Primary heat recovery occurs when the process exhaust vent stream gets directed through a heat exchanger. This crosses the outlet of the oxidizer exhaust, before the inlet to the oxidizer. This recovers (recuperates) heat from the exhaust to pre-heat the air entering the combustion chamber, which reduces the amount of heating necessary for the process, as well as the gas needed to reach oxidation temperatures.
Secondary heat recovery occurs when you use waste heat from the oxidizer to support a secondary process such as providing heat for an industrial oven, or wash lines for multi-stage washers. This occurs when directing either fresh air or process air through a heat exchanger, which crosses the outlet of the oxidizer exhaust, and sends it to a secondary process. This recuperated heat from the exhaust is often enough to complete drying or curing operations. The energy savings alone can repay your investment in your equipment in one year’s time.
Recuperative Thermal Oxidizers work best for processes where waste liquids need to be treated, for animal feed production, coil coating, and automotive dyno testing.