Thermal Oxidizer | HiTemp TechnologyThermal Oxidizer System Types - Which is Best?

A thermal oxidizer, also known as a thermal incinerator, is a process unit that reduces air pollution in many industrial facilities by decomposing hazardous gases at a high temperature prior to releasing them into the atmosphere.

When chemicals, solvents, or petrochemicals are carried in tanks, the gas vapor that remains in the tank still contains hazardous air pollutants (HAPs) and volatile organic compounds (VOCs) that are harmful to the atmosphere and the environment. Thermal oxidizers are installed at factories to destroy HAPs and VOCs from industrial air streams before being released to the earth’s atmosphere via a chemical oxidation reaction. Because these pollutants are hydrocarbon-based, when destroyed via thermal combustion, they are chemically oxidized to form CO2, water vapor (H2O), and heat. Thermal oxidizers are typically able to destroy in excess off 99% of all pollutants to meet strict environmental regulations for gas and liquid pollution control.

Three main factors in designing effective thermal oxidizers are temperature, residence time and turbulence:

  • The temperature needs to be high enough to ignite the organic components in the waste stream. Most organic compounds ignite at temperatures between 590oC and 650oC. To ensure near destruction of hazardous gases, most basic operators are set to much higher temperature levels.
  • Residence time refers to ensuring there is enough time for the combustion reaction to occur.
  • Turbulence is the mixture of combustion air with hazardous gases.

The simplest type of thermal oxidizer is the direct fired thermal oxidizer, which does not include any type of heat recovery system to recover a portion of the waste heat generated by the combustion process. This is typically the least expensive thermal oxidizer, but it will incur the highest operating costs and fuel consumption when compared to other types of oxidizers.

In order to recover the heat generated during the combustion process, thermal oxidizers frequently have a form of heat recovery to reduce the high levels of fuel required for oxidation. Levels of heat recovery generally increase with decreasing levels of VOC/HAP. Heat recovery can either be recuperative or regenerative.

  • Regenerative thermal oxidizers (RTOs) are one of the most widely accepted air pollution control technologies. These devices work by preheating input gases in a ceramic bed to partially oxidize them, then passing the preheated gases into a combustion chamber to reach the target oxidation temperature. The ceramic bed is typically heated from a previous oxidation cycle, utilizing the heat generated cyclically thus producing an extremely efficient device. RTO thermal efficiency can reach 95%. The alternating airflow direction in the media beds maximizes energy recovery within the oxidizer to reduce fuel consumption and save operating costs.
  • Recuperative heat thermal oxidizers (RCOs) are less commonly used devices that recover heat by passing the hot exhaust gas through a primary and/or secondary non-contact heat exchanger. This heat-exchanger heats the incoming air flowing to the oxidizer to reduce operating costs. A recuperative thermal oxidizer system can have a single heat recovery device or multiple heat recovery devices.