ECOLOGIST PROFORTE is the PROBAT exhaust air cleaning system for maximum cleaning efficiency. The exhaust gases produced during roasting are piped through a ceramic bed which has an internal temperature of 900 to 1,100 °C. This enables the thermal combustion of the emissions without generating the nitric oxides associated with catalysers. The ceramic bed is heated up electrically, then its temperature is maintained by the exhaust gases’ reaction (or by feeding gas in through nozzles in standby mode). The direction of flow is cyclically reversed to keep the high temperature in the middle of the bed. This results in thermal efficiency of approx. 95 to 98 %. As an option, a buffer tank can be added to the system to catch the uncleaned exhaust air which would otherwise escape during the changeover. Once the direction of flow has been reversed, this air is then incorporated into the cleaning process again. The limits stipulated in Germany’s air pollution control regulations are reliably observed, whether a buffer tank is used or not.