While techniques for air preheating (i.e. regenerative and recuperative furnaces) are widely used in the preheating furnaces, they have the drawback of increasing NOx emissions. The flameless burner technologies carry out out combustion under diluted oxygen conditions using internal flue gas recirculation and the flame becomes invisible. Flameless airfuel combustion uses air as oxidizer, while flameless oxyfuel uses commercial oxygen as an oxidant. Flameless oxyfuel gives high thermal efficiency, higher levels of heat flux, and reduced fuel consumption compared to conventional oxyfuel These benefits are combined with low NOx emissions and better thermal uniformity.  

In addition to significantly reducing fuel consumption and CO₂ and NOx emissions, by convering to a flameless oxy-fuel combustion system enabled a plant in the US to increase material throughput by 25% and reduce scale formation by 50% (US EPA, 2010. p. 28).