Introduction To Thermal Oxidizer Systems, How They Work, And Why You Need Them

Catalytic oxidizers are comparable to thermal oxidizers (catalytic oxidizers use a catalyst to promote the oxidation reaction). Temperature (high enough to ignite the organic contents in the waste stream), residence time (enough time for the combustion reaction to occur), and turbulence (mixing of the combustion air with the waste gas) are all important design parameters in an ideal thermal oxidizer system.

 

A straight thermal oxidizer’s operation is straightforward. A vapor stream comprising VOC contaminants is guided into an oxidizer chamber that has been carefully engineered to account for the three Ts: time, turbulence, and temperature. The firing rate of the Gas Train and Burner assembly is modulated to maintain an increased setpoint temperature in the oxidizer chamber. VOCs react with oxygen in the hot chamber and break down into less hazardous components such as CO2 and water. Finally, the vapor stream is expelled through the exhaust stack, where the VOCs are eliminated to comply with the air permit criteria and provide an A-1 thermal oxidizer service.

Thermal Oxidizer Systems

A thermal oxidizer system typically incorporates some type of heat recovery to reduce the amount of fuel required for oxidation. With lowering incoming VOC/HAP concentrations, the percentage of heat recovery in the design of thermal oxidizers normally increases.

Recovery from heat can be either recuperative or regenerative. Heat is recovered by transferring heated exhaust gases via a non-contact air-to-air heat exchanger to heat the incoming air to the oxidizer in recuperative heat recovery. Hot exhaust gases and cool incoming gases alternately travel through a fixed bed, which is commonly made of ceramics, in regenerative heat recovery.

 

Monitoring Thermal Oxidizer Systems

The outlet exhaust gas VOC concentration and the combustion chamber temperature are the major indicators of thermal oxidizer performance for VOC management. The outlet exhaust gas CO concentration, exhaust gas flow rate, fan current, outlet CO2 concentration, outlet O2 concentration, and auxiliary fuel line pressure are further indicators of thermal oxidizer performance. Except for output VOC and CO2 concentrations in thermal oxidizer systems, which would not be monitored for a CO emissions limit, the indicators of performance for CO control are the same as for VOC control.