Thermal oxidation for chemical operations (manufacture of pigments)

Posing the tasks

At the facilities of the worldwide leading manufacturer of metallic and pearl-gloss pigments, solvent laden exhaust air ensues during one step in the production process. This is extracted by means of vacuum pumps, which, in so doing, dries the product. As this vacuum extraction cannot be realised without the inflow of external air, the exhaust air mixture is explosive and classified as EX-RL in the Zone 0.

Solution / Highlights

Due to the extremely high solvent loading, a regulated thermal oxidation system was considered to be the best suited process for cleaning the exhaust air ensuing during production. In the first step, the exhaust air is cooled down by means of a cold water heat exchanger. During this step, a portion of the solvent condenses out and can continue to be used at other locations. The exhaust air subsequently enters the combustion system.

This is outfitted with three safety elements for flame and explosion suppression. A controllable heating oil burner is available in case of low solvent concentrations or for heating up to the required heat energy for oxidation of contaminants following system shutdown.

Due to severe space restrictions for setup at the customer's site, the thermal oxidation system was installed on the roof of the production facility.  In order to keep the system weight as low as possible, the combustion chamber was not walled-in with masonry, as is commonly done, but was internally insulated with high-temperature ceramic fibres.