The fluidized-bed furnace introduced in 2010 has no distributor pipes or plates

Photo: Wire Körner

75% less energy required

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Körner was founded in 1928. Therefore, right after World War II, the company could already draw on solid experience as heat treatment specialists. Reconstruction of the company was completed in the early 1950s. At that time, with a workforce of forty, Körner produced heat treatment and galvanizing equipment for customers around the globe. Since then, commitment to the development of energy and resource-saving plants with minimized environmental footprint has run through the company history like a thread. Initially, the plants used to be fired with oil or long-distance gas and the furnaces were controlled manually. The main concern at that time was to heat the wire rod up to the proper temperature. Regulating devices, as known today, did not exist and many metallurgical processes were not yet fully explored. Therefore, all the more important were the experience and intuition of the individual operator. Considerate use of resources was not an issue yet. Energy was cheap and heat insulation had low priority. As there were no adequate filter systems, emissions were generally accepted as normal. A rethinking in plant engineering followed in the wake of the oil crises in the 1970s. There was no newspaper sparing the issues of ozone depletion and dying forests. Efficient energy use became a central engineering task. Already in the early 1980s, Körner supplied plants with burner systems that consumed significantly less energy. Today’s plants consume only one fourth of the energy required by plants of the post-war period. Körner has remained an innovative company up to the present day. In 2008, the subsidiary Wire Körner was founded as a reaction to the growing importance of heat treated wire rod. Körner sees itself as technology leader. By cooperating with international R&D institutes, the company has repeatedly succeeded in implementing developments in an impressively short time, for example the low-maintenance fluidized-bed furnace, launched at the “wire 2010” trade fair. There Körner presented a furnace design hard to image before: a heat treatment furnace without distribution pipes and tiles. Eliminating the distribution elements leads to much reduced flow resistance. Hence the required blower capacity can be lower than that of competing designs by about 20 percent.
The simple design lowers the costs associated with the investment. As the combustion gas is premixed outside the furnace, the new design achieves a uniform fuel-air mixing ratio throughout the fluidized bed and a homogeneous temperature distribution over the width and length. This results in higher combustion efficiency and lower emissions of unburned hydrocarbons. Further examples are Körner’s proprietary burner technology, automatic zinc coating control and the patenting furnace with furnace atmosphere control, which allows Körner’s customers to make products of a uniformly high quality and in a highly efficient manner. While 60 years ago the furnaces used to be operated by up to eight people, nowadays the furnace plants operate more or less automatically and the measuring and control technology contributes largely to the quality of the final products. Whereas more than half a century ago the furnaces were heated “by intuition”, today modern process control sets the temperature in the furnace with an accuracy of ± 2 °C. Touchscreens have meanwhile definitely replaced the viewing glass, which the furnace operator used to check the condition inside the furnace.

The homogeneous temperature distribution inside the furnace chamber not only ensures the same product quality from batch to batch. Today the desired product quality is attained irrespective of where the wire is positioned inside the furnace. 60 years ago, this was completely different: wire rod placed in the middle of the furnace had often different properties than those running at the sides. The achievements during 60 years of continuous development are impressive. Körner has cut both energy requirements and emissions by about 75 percent since the 1950s. Peter Kordt, managing partner of the Körner group, is committed to further reducing the specific energy requirement of heat treatment plants.