At first thermal oxidizers look like direct fired heaters, but as you look closer there is way more to that. As I explained in my previous posts, the goal is to reach a degree of destruction of the waste material. So, we need to quantify a parameter for this VOC (Volatile Organic Compound) or HAP (Hazardous Air Pollutant) destruction: DRE.
What is DRE?
DRE stands for Destruction Removal Efficiency in the context of thermal oxidizers. It refers to the efficiency with which Volatile Organic Compounds (VOCs) and Hazardous Air Pollutants (HAPs) are destroyed or removed in the thermal oxidation process.
Typically, if a 95% DRE is required, then a residence time of half a second is adequate. The three main factors in designing effective thermal oxidizers are temperature, residence time, and turbulence. The temperature needs to be high enough to ignite the waste gas, and most organic compounds ignite at temperatures between 590 °C (1,094 °F) and 650 °C (1,202 °F).
Once all the fuel, wastes, and air are combined, several intimately connected and simultaneous conditions must exist to achieve the DRE required. The mixture must be:
- Exposed to a sufficiently high temperature
- For an adequate period of time
- In a relatively turbulent environment
to enable the oxidation reactions to reach the degree of completion needed to achieve the waste destruction efficiency required. These conditions are known as the “three Ts” in the combustion industry.
The vessel that provides the environment for these conditions is known by various designations depending on the application. Furnace, TO, combustion chamber, and incinerator are all common names for the oxidation environment. For consistency, we name it as TO. To provide the environment needed for the three conditions to be optimized, the TO must have the correct volume and geometry.
