FLOX is a combustion process developed by WS Wärmeprozesstechnik GmbH.
In April 1990 Joachim Alfred Wünning made experiments with industrial gasoline engines thereby observing that beyond a temperature of 850 °C the flames were blown away. The German word "flammenlose Oxidation" (flameless oxidation) is the origin of the name for the FLOX-Technlogy that was derived from the effect. Its specific advantages led to additional funding including a project "FLoxCoal" at the Stuttgart University to engineer a prototype of an atomizing burner for coal without flame reactions.
The NOx formation is specifically located in the flame front so that by suppressing peak flame the NOx emission can be reduced theoretically to zero. In the practical implementations in current burner technology a reduction of 20% was observed for Rhenisch brown coal and 65% for Polish black coal.
The role of combustion temperature in NOx formation has been understood for some time. Reduction of the combustion temperature in gasoline engines, by reducing the compression ratio, was among the first steps taken to comply with the U.S. clean air act in the 1970s. This lowers the NOx emissions by lowering the temperature at the flame front.