Direct Thermal Oxidation involves simply applying heat to the contaminated air until the temperature is raised enough for combustion to occur. Organic compounds have a temperature at which they will begin to oxidize even if no direct flame were present. For example, if a organic compound has an auto ignition temperature of 932°F / 500°C, it would begin to convert to carbon dioxide and water, assuming enough oxygen is present.
In practice, a higher temperature is needed to assure that you get good destruction efficiency. The actual temperature could be up to double the auto ignition temperature depending on the desired removal.
With Direct Oxidizers, nothing additional is done except to allow the temperature to increase. This takes energy. If the inlet load of solvent or VOC is high enough, then this is the best way to approach control. Simply heat the gas.
As the amount of solvent available decreases, the energy requirement for the supplemental burner increases. You have to burn more and more fuel. To avoid costly operating expense, it is possible to install an Air-to-Air Heat Exchanger. This will take the hot exhaust gas and preheat the incoming cold gas. By recovering part of the energy, operating cost can be controlled.
The process air stream, at a temperature of approximately 140° F (60° C), enters the Deep-Bed Vapor Phase Carbon Adsorption System between two horizontal beds of selected activated carbon. The air stream separates, flowing through the upper and lower beds of activated carbon, where the contaminants are removed, prior to the air being discharged from the system.
Air-to-Air Heat Exchangers
Air-to-Air Heat Exchangers operate by taking the outlet hot gas and passing this through a heat exchanger with the cold inlet air on the other side of the tubes in the heat exchanger. The cold air is heated up by the outlet air. Economically, 50% thermal efficiency is considered as an Industry standard but the actual efficiency can vary from this depending on the design requirements.
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- All performance levels are guaranteed.
- Any design configuration can be provided, including vertical and horizontal.
- All safety features with UL, FM or other approved components as needed.
- Complete engineering, including tail gas treatment from one source.
- Shop fabricated capacities of less than 20,000 cfm (34,000 m3/h) are available.