thermal oxidizer system

Thermal Oxidizer Systems: Working, Treatment Process, And More

What Is A Thermal Oxidizer System And What Does It Do?

The pollutants in polluted exhaust gas react with oxygen in a temperature-controlled atmosphere using the principle of “thermal oxidation,” a combustion process. Before releasing the polluted exhaust gas back into the atmosphere, the chemical oxidation reaction eliminates the pollutants in it. CO2, water vapor, and heat are released in a harmless manner.

Many processes, such as printing ink drying, paint baking, and polymer curing, produce flammable, hazardous solvent fumes. These solvent vapors constitute an explosion or fire hazard in the baking or curing oven, thus they are diluted well below their lower limit of flammability by adding huge amounts of dilution air. The contaminated air is subsequently expelled from the oven and sent through a thermal oxidizer unit, where the solvents are destroyed.

How Does A Thermal Oxidizer System Work?

thermal oxidizer systemsThermal oxidizer systems use ceramic media beds with improved thermal efficiency, whereas TROs use traditional metallic shell-and-tube heat exchanger systems. Using a high-pressure fan and pneumatic flow control valves, incoming process emissions are sucked or pushed through the first ceramic bed in a dual-bed thermal oxidizer.

The unclean stream exits the ceramic bed and enters the combustion chamber, where burners swiftly break down polluted compounds with 99 percent destruction efficiency. This cleansed stream is directed to a secondary ceramic bed, where it might lose up to 97 percent of its heat value to the exchange medium.

The pneumatic valves of thermal oxidizers occasionally reverse the flow direction, allowing the recovered heat to be reused. While clean, cool air is discharged into the atmosphere, the ceramic bed that recovered heat from the purified stream is employed to warm the incoming pollutants.

This isn’t the only arrangement available, but it’s the most straightforward for learning how a thermal oxidizer system functions. Multi-chamber designs provide an alternative, although the same general principles apply.

What Is The Processes Of Treatment In A Thermal Oxidizer Unit?

Contaminants in such gases are destroyed by TO units and other technologies. A thermal oxidizer unit eliminates different impurities from a waste air stream, particularly hydrocarbons and volatile organic compounds (VOCs). Thermal combustion destroys hydrocarbon-based pollutants, which are chemically reduced to produce carbon dioxide (CO2) and water (H2O).

Thermal oxidizers regulate combustion conditions to ensure that VOCs, CO, and volatile HAP emissions are completely destroyed. For a complete combustion reaction, there must be enough time, temperature, mixing, and oxygen concentrations. The temperature in the waste gas stream must be high enough to ignite the organic contents. The residence time must be sufficient for all pollutants to completely decompose. Combustion requires oxygen (O2), and there must be enough of it for all of the hydrocarbons present to oxidize. Mixing ensures that the O2 present comes into touch with the hydrocarbon, allowing for complete combustion.

The thermal oxidizer system design determines the residence period and mixing. During operation, the temperature and oxygen concentration are monitored. In the next paragraphs, we’ll go through the fundamental TO design.

The process blower extracts waste gas from the source that contains hydrocarbon vapors (pipeline, tank, etc.). A filter, a detonation arrestor, a moisture separator, and a primary flame arrestor are all used to filter the waste gas. For main protection, several TOs feature a detonation arrestor. After then, the waste gas enters the combustion chamber. Before entering the reaction chamber, the waste gas flows through a heat exchanger in some thermal oxidizer systems.

The combustion air blower delivers the air (approximately 21% O2) required by the reaction chamber’s fuel gas burner. The hydrocarbons are eliminated, and the cleaned air is released into the environment.

Thermal oxidation necessitates keeping the process gas vapors at a high enough temperature for the reaction to complete. At an operating temperature of 1,400°F and a retention time of one second, 99 percent of the material is destroyed. At 1,500°F, the majority of TO combustion chambers are built and tested for a 1-second retention time.

The programmable logic controller receives data from the influent LEL meters, an O2 detector, and an effluent PID (PLC). In reaction to this data, the PLC controls particular valves to ensure safe, efficient, and effective treatment. Data is also logged by the PLC and downloaded for the project report.

Auxiliary fuel is provided to maintain adequate destruction temperatures when the VOC concentration is low. Auxiliary fuel use can be reduced in two ways. A heat exchanger in a recuperative TO preheats the incoming gas using heat from the oxidizer exhaust. A precious metal catalyst is used in a catalytic thermal oxidizer unit to lower the oxidation temperature. As in a recuperative catalytic TO, the two processes can be coupled.

Standard thermal oxidization cannot be used to treat some substances, such as halogenated and sulfonated compounds. This is because acidic gases are produced during the oxidation process. Evoqua offers customized TOs to handle various chemical groupings. Each one has a unique coating that protects the unit from acid vapors, as well as a caustic exhaust scrubber that removes the acid vapors before they are emitted.