Projektinfo – Detailed information on energy research

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Ceramic radiant tube in test laboratory
© WS Wärmeprozesstechnik GmbH
New applications for proven technology
Projektinfo 07/2006
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Flameless combustion

What at first sounds like a paradox – flameless combustion – is being implemented in an increasing number of industrial high temperature burners. With a sophisticated mixture of combustion gas, combustion air, and recirculating exhaust gas, it is possible, with so-called FLOX burners, to maintain combustion without flame. The decisive advantage is that even with high furnace temperatures, almost no nitrogen oxide is formed.

The process also enables efficient utilisation of fuels, as the exhaust gases can be used for preheating the combustion air. The nitrogen oxide emissions alone represent a significant challenge in high temperature processes. Often, the threshold values defined in the German Technical Instructions on Air Quality Control (TA Luft) can only be achieved with costly downstream purification of the exhaust gases. Atmospheric nitrogen oxidises to a notable extent in the hot zones of the flame front. In flameless combustion, these temperature peaks do not occur, and a constant furnace temperature of up to around 1,400 °C can be maintained with low nitrogen emissions. Thus, it is no surprise that now, 15 years after the first commercial FLOX burner was commissioned, there are many varieties available, for a broad range of applications. This technology is used especially in the steel industry and in burners for heat treatment.


The potential of FLOX technology is, however, far from exhausted. Various projects, some of which sponsored by the German Federal Ministry of Economics and Technology (BMWi) and the European Union, are exploring the utilisation of lean gases and biofuels, power plant technology, and combined heat and power generation. Devices using FLOX technology have also been developed for the reformation of natural gas to hydrogen. Compared to burners with no preheating, it is thus possible to reduce the fuel consumption by up to 50%.


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