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RTO (Ceramic Bed) vs an HTT RCO (A-A Exchanger catalytic)
The emission control industry appears to have created a stream of misinformation and untruths concerning the fuel cost comparison between RTO and RCO systems. Simply put, they do not tell customers that natural gas at 1600oF (870oC) has half the heat value than it does at 70oF (21oC). Customers pay for FT3 of natural gas, not BTUs. So when suppliers calculate a 1,000,000 BTU operating cost it is really a 2,000,000 BTU operating cost.
An HTT RCO uses an Air to Air preheat exchanger and a precious metal catalyst bed, allowing oxidation to occur at approximately 550-600oF (288-315oC). This lower temperature requirement reduces the amount of natural gas needed to fuel the VOC abatement system and the overall size of the incinerator. Catalysts typically used for VOC incineration include platinum and palladium.
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RTOs use a high-density media, such as a ceramic-packed bed still hot from a previous cycle to preheat an incoming VOC-laden waste gas stream. These preheated, partially oxidized gasses then enter a combustion chamber where they are heated by auxiliary fuel (natural gas) combustion to a final oxidation temperature typically between 760oC to 820oC (1500oF to 1600oF) and maintained at this temperature to achieve maximum VOC destruction. Temperatures of up to 1100oC (2000oF) may be achieved, if required, for very high control efficiencies of certain toxic VOCs. The purified, hot gases exit this chamber and are directed to one or more different ceramic-packed beds cooled during an earlier cycle. Heat from the purified gases is absorbed by these beds before the gases are vented to the atmosphere. The reheated, packed bed then begins a new cycle by heating another incoming waste gas stream.
When the exhaust stream contains condensible vapors, these will condense on the packing and then will be vaporized again when the flows are reversed, once again releasing the condensibles back into the exhaust stream.
An HTT RCO uses an Air to Air preheat exchanger and a precious metal catalyst bed, allowing oxidation to occur at approximately 550-600oF. This lower temperature requirement reduces the amount of natural gas needed to fuel the VOC abatement system and the overall size of the incinerator. Catalysts typically used for VOC incineration include platinum and palladium (Gay, 1997; Biedell and Nester, 1995).