CATALYTIC THERMAL OXIDIZER (CTO)
Catalytic oxidation is a process to treat waste air or gases.
Usually traditional oxidation processes are running at temperatures higher than 750°C. In case a few organic compounds are present in the gas stream, to keep these temperatures, the incineration process needs a high quantity of additional fuel.
With the catalytic oxidation the additional fuel can be saved by means of a special catalyst that makes possible the oxidation of organic compounds at lower temperatures (for example from 250 to 350).
The process is very simple. The waste air or gas is sucked by a fan, the stream passes through a heat exchanger which heat up it and then feed into the catalytic reaction chamber. The pre-heating is done by the hot stream (cleaned gas), in outlet from reaction chamber, passing on the other side of the exchanger; in this way it is cooled down before sending it through the stack.
A start up burner ensures that the gas stream has the right oxidation temperature before getting in contact with the catalyst. There, the organic compounds reacts, producing CO2 and H2O and heating up the gas and the catalyst.
If the concentration is high enough, the process is running without support fuel.
Heart of the process is the catalyst. If the composition of gas is known and it hasn’t changes during the years, the catalyst can work for more than 5 years.
Limit of this process is the presence in the stream of compounds that can damage the operation of catalyst, as for example dust, silicon and similar substances.
If the concentration of organic compounds is too high, the temperature exceed the project value and it is necessary to cool down the stream going to the catalyst; this can be done by water or fresh air injection or avoiding the preheating of the stream through the heat exchanger.