Lean gas burners in a steelworks

Arcelor Mittal Bremen GmbH, Bremen (Germany)

During the search for an eco-friendly and cost-effective combustion system for the steelworks in Bremen, Arcelor Mittal Bremen GmbH struck lucky with SAACKE. The SAACKE lean gas burner uses available lean gases to generate energy - an economically and ecologically expedient technology that impresses immediately.

Large volumes of lean gases are traditionally produced in steelworks which have to be discharged in many cases by flaring. The SAACKE SSB-LCG lean gas burner allows these LCV gases such as blast furnace gas to be used thermally without any supporting fuel over a wide control range and with a particularly short flame.

Through the use of the SAACKE lean gas burner, Arcelor Mittal Bremen GmbH saves around 6.8 million cubic meters of natural gas a year. As a result, the company's energy costs were reduced by some 2.3 million euros in the first year of operation alone. The CO₂ emissions were reduced by roughly 8,400 tonnes per year. And not only that: Thanks to the blast furnace gas scrubbing, the dust and sulfur dioxide emissions also lie well below the admissible limits.

In this way the SAACKE combustion system enabled Arcelor Mittal to significantly cut its fuel costs, to become independent of the fluctuations on the heat market and at the same time to make an important contribution to environmental protection. It is therefore hardly surprising that a second Arcelor-Mittal boiler plant was soon installed with SAACKE SSB-LCG lean gas burners, and that a similar plant is now also in operation at Arcelor Mittal in Ghent, Belgium.

The lean gas combustion system consists of a SAACKE SSB swirl burner with a special burner muffle into which the gas with low heat value is fed. The burner this achieves an almost emission-free combustion - completely without the use of supporting fuels.

Fuel with high heat value (here: natural gas) is required only for the start-up of the plant; as soon as the burner and its muffle have reached the operating temperature, the starting fuel supply can be switched off. Within a very short time the flame is burning only with lean gas.

The combustion air of the SAACKE SSB-LCG consists of two partial streams which flow into the combustion chamber with an extreme swirl. This swirl and the hot lining of the muffle ensure that the lean gas is reliably ignited and burns with an absolutely stable flame at all of the firing rates.

Thanks to the good mixing of the combustion air and fuel, the temperature profile is extremely homogeneous and relatively cold. The NO_x emissions are therefore very low and lie well below even the future demands.

Combustion air, core air and fuel are supplied with an optimum balance at all firing rates thanks to a fuel/air mixing ratio control system.