The air stream is extracted by a fan designed to overcome the pressure drops of the system. An exhaust adjustment system (inverter) is added when there is a variable flow rate and you want to reduce production pressure fluctuations as much as possible. This also optimises energy consumption and adapts operation of the abatement plant to production requirements.
The effluent, before being sent to the catalyst, is preheated in a fume/air exchanger where, in countercurrent, the heat of the purified effluent leaving the catalytic reactor is exploited before being sent to the stack. This heat exchange system recovers 70% of the energy, allowing the plant to be self-sufficient (no auxiliary fuel consumption) starting from an incoming VOC concentration of 3-4 g/Nm³.
An auxiliary burner, located in a specific reactor, integrates the temperature, if needed, before the air stream crosses the catalyst. The type of catalyst, with precious metals or common metal oxides, honeycomb or in pellets, is chosen depending on the organic substances to be abated. The new catalyst formulations can also abate chlorinated or sulphurised organic compounds.
There is also a regenerative version of the catalytic combustion plant which is ideal for low concentrations. The treatment process remains the same, while the heat recovery system is changed, no longer recuperative but regenerative, therefore introducing two ceramic mass tanks, acting as heat storage tanks in place of the tubular heat exchanger. This version can push energy recovery to 95% and become self-sufficient, starting from a concentration of 1.5 g/Nm³.