Flame resistant
High temperature furnaces, such as those used in the metallurgical industries for metal melting and reheating, are notoriously inefficient because of the large amount of heat leaving the furnace in the flue gases. Over the years this heat has been captured by incorporating waste heat recovery systems to preheat the combustion air. This can be done using recuperative burners or more recently, the development of compact, high-effectiveness regenerative burners. The regenerative burners can preheat the air to well over a 1,000°C, producing energy savings of around 60 per cent. However, these levels of air preheat temperatures result in increased flame temperatures, which produce high levels of oxides of nitrogen (NOx).