Thermal oxidizer
A process stream with hazardous gases is introduced into a firing box through or near the burner and enough residence time is provided to get the desired destruction removal efficiency (DRE) of the VOCs.
Most direct-fired thermal oxidizers operate at temperature levels between 980 °C (1,800 °F) and 1,200 °C (2,190 °F) with air flow rates of 0.24 to 24 standard cubic meters per second.
[1] Also called afterburners in the cases where the input gases come from a process where combustion is incomplete,[1] these systems are the least capital intensive, and can be integrated with downstream boilers and heat exchangers to optimize fuel efficiency.
Thermal Oxidizers are best applied where there is a very high concentration of VOCs to act as the fuel source (instead of natural gas or oil) for complete combustion at the targeted operating temperature.
[citation needed] One of today's most widely accepted air pollution control technologies across industry is a regenerative thermal oxidizer, commonly referred to as a RTO.
The preheated gases enter a combustion chamber that is heated by an external fuel source to reach the target oxidation temperature which is in the range between 760 °C (1,400 °F) and 820 °C (1,510 °F).
VAMTOX units have a system of valves and dampers that direct the air flow across one or more ceramic filled bed(s).
[5] In a flameless thermal oxidizer system waste gas, ambient air, and auxiliary fuel are premixed prior to passing the combined gaseous mixture through a preheated inert ceramic media bed.
[6] The gas mixture temperature is kept below the lower flammability limit based on the percentages of each organic species present.
Waste gas streams experience multiple seconds of residence time at high temperatures leading to measured destruction removal efficiencies that exceed 99.9999%.
[citation needed] Premixing all of the gases prior to treatment eliminates localized high temperatures which leads to thermal NOx typically below 2 ppmV.
Evolving from the previous fixed-bed and carbon rotor concentrators, the FBC system forces the VOC-laden air through several perforated steel trays, increasing the velocity of the air and allowing the sub-millimeter carbon beads to fluidize, or behave as if suspended in a liquid.
When these systems are used special design considerations are utilized to reduce the probability of overheating (dilution of inlet gas or recycling), as these high temperatures would deactivate the catalyst, e.g. by sintering of the active material.
[citation needed] Catalytic oxidizers can also be in the form of recuperative heat recovery to reduce the fuel requirement.
