Thermal oxidizer
A thermal oxidizer (also known as thermal oxidiser, or thermal incinerator) is a process unit for air pollution control in many chemical plants that decomposes hazardous gases at a high temperature and releases them into the atmosphere.
Thermal oxidizers are typically used to destroy hazardous air pollutants (HAPs) and volatile organic compounds (VOCs) from industrial air streams . These pollutants are generally hydrocarbon based and when destroyed via thermal combustion they are chemically oxidized to form CO2 and H2O. Three main factors in designing the effective thermal oxidizers are temperature, residence time, and turbulence. The temperature needs to be high enough to ignite the waste gas. Most organic compounds ignite at the temperature between 590 °C (1,094 °F) and 650 °C (1,202 °F). To ensure near destruction of hazardous gases, most basic oxidizers are operated at much higher temperature levels. When catalyst is used, the operating temperature range may be lower. Residence time is to ensure that there is enough time for the combustion reaction to occur. The turbulence factor is the mixture of combustion air with the hazardous gases.
The simplest technology of thermal oxidation is direct-fired 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.
Also called afterburners in the cases where the input gases come from a process where combustion is incomplete, these systems are the least capital intensive, but when applied incorrectly, the operating costs can be devastating because there is no form of heat recovery. These 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.
One of today’s most widely accepted air pollution control technologies across industry is a regenerative thermal oxidizer, commonly referred to as a RTO. RTOs use a ceramic bed which is heated from a previous oxidation cycle to preheat the input gases to partially oxidize them. 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). The final temperature may be as high as 1,100 °C (2,010 °F) for applications that require maximum destruction. The air flow rates are 2.4 to 240 standard cubic meters per second.
...
Wikipedia