The recuperative thermal oxidation is a VOC treatment technology that requires lower investment costs than the regenerative one, but has higher management costs due to higher fuel consumption.
Recuperative thermal oxidation is a technology that makes it possible to eliminate pollutes that are in a gas when subjecting the latter to a sufficiently high temperature. For the process to be effective and for the pollutants to be able to fully oxidised, it is necessary to maintain a minimum temperature (between 700ºC and 1200ºC) for a minimum time (0.6-2 seconds).
The pollutants that are normally eliminated with this technology may be organic (VOCs, odours, etc.) or inorganic (CO, H2S, HCN, etc.). It is a technology that is used when then gas flow is below 50,000 Nm3/h and the concentration of pollutants is 5-20 g/Nm3.
This treatment technology has the following advantages:
- High efficiency and reliability.
- Flexibility towards the gas flow to be treated and the concentration of pollutants.
- Great versatility as regards the type of pollutants.
- Easy to operate.
This technology consists of a combustion chamber with a burner and heat exchanger in which the incoming air is preheated with the outgoing air. It allows thermal recovery efficiency of the order of 65%. Working temperatures can go up to 1,450ºC.
In order to save fuel, a heat exchanger preheats the gases to be treated while the gases the leave the combustion chamber are cooled. Recuperative oxidation plants have a recuperator that utilizes the outgoing hot gases from oxidation that come from the combustion chamber to preheat the incoming air to be treated, which implies saving energy.
Since it is necessary to heat the gases of the process to such a high temperature, oxidation plants involve the auxiliar fuel consumption. This is why is very important to be able to recover whenever possible, both the heat provided and produced during oxidation.
However, it should be underlined that when the heat is not recovered from the purified gases, or the concentrations of pollutants are low, the operating costs are high because of the energy costs.