The term regenerative thermal oxidation refers to the cleaning of exhaust air and waste gas by means of thermal oxidation with the highest possible heat recovery. The exhaust air is cleaned of all organic pollutants. In thermally regenerative oxidation plants, or RTO technology for short, such exhaust gases are converted into the components water and carbon dioxide at temperatures between 750 °C and 1000 °C and are therefore harmless to the environment. However, some pollutants also produce oxidation products such as SO2, HCl, NOx or SiO2. These require further process steps, such as purification using SCR or scrubber technology, as they may not be released into the environment above a certain concentration.
The basic prerequisite for being able to utilise thermal oxidizers is, that the pollutants in the exhaust air are combustible. RTO systems are particularly suitable for higher pollutant concentrations (> 1 gC/m³), as the need for secondary fuels can be greatly reduced or completely eliminated.
Oxidation takes place in a specially dimensioned combustion chamber at reaction temperatures of 700 °C to 1000 °C. Only high-temperature resistant material is used for the combustion chamber. The dwell time in the combustion chamber is very short. So that the entire heat output does not have to be realised via a burner, the RTO is divided into at least 3 chambers, each of which is filled with beds of heat exchanger material.
These are ceramic honeycomb or saddle bodies that absorb the thermal energy of the hot clean gas and transfer it to the cold raw gas. For this purpose, hot clean gas and cold raw gas flow alternately through the heat exchanger beds. Overall, this process is characterised by a high level of preheating of the raw gas, so that a large proportion of the energy requirement is saved. If the content of hydrocarbons in the exhaust air is constantly high enough (from approx. 1-2 g/m³), the RTO works without additional combustion of a secondary fuel.
The alternating supply of raw and clean gas to the heat exchanger chambers is realised via a PLC-controlled flap system. After each changeover cycle, the chamber previously pressurised with raw gas is purged of residual impurities using purge air. This reliably prevents impermissible emission peaks when switching over. Tandem dampers with double seals, which can also be pressurised with sealing air to achieve 100% tightness, are used to ensure compliance with the sometimes very demanding clean air limits.
The thermal oxidizers from Wessel-Umwelttechnik work extremely efficiently with maximum heat recovery rates. The high clean gas requirements are easily met, depending on the composition of the exhaust gases.
With regard to the purification of exhaust air by means of oxidation, the systems score with a wide range of applications - provided that the pollutants are organic. Many of these can be cleaned in thermal oxidizers. For liquid pollutants, the process is the only one that can be used.
Very often the exhaust air contains both inorganic and organic components. For such complex tasks, Wessel-Umwelttechnik GmbH has established itself as a suitable partner for its customers over decades. This is where the advantage of Wessel-Umwelttechnik GmbH's broad product portfolio comes into play.
Furthermore, many industrial and municipal sectors are faced with tasks involving corrosive vapours. Thanks to the materials expertise of Wessel-Umwelttechnik GmbH, both reliable and cost-optimised solutions can be implemented here.
Wessel-Umwelttechnik focuses primarily on the following industries and areas of application, where particularly sophisticated customised solutions are required:
