Das Projekt "Energy savings by improvement of combustion air preheating by means of an upstream heat exchanger" wird vom Umweltbundesamt gefördert und von ThyssenKrupp Stahl AG durchgeführt. Objective: Use of low temperature waste heat for additional preheating of the combustion air and for prevention of low temperature corrosion. This technique yields an increase of the plant availability and a longer life of the recuperator by preventing the temperature from falling below the dew point to prevent corrosion. Innovative aspects: concept first realization. Long testing and measurement period to assess energy saving and efficiency and payback time. General Information: In industrial furnaces a part of the heat from the flue gas is used to pre-heat the combustion air. When intensive use is made of the heat from the flue gas, there is frequently a great drop in temperature to below the dew point. When the fuel gases are loaded with aggressive materials, the passing of the dew point causes low temperature corrosion on heat exchanger components. As a result of this, the heat exchanger is increasingly destroyed which entails constant worsening of efficiency very rare (once to twice per year) with some plants, i.e. reheating furnaces in the steel industry, so that more fuel is consumed over a long period because of defective air pre-heating insulation and the environment is thus burdened more than is required with an intact installation. A heat exchanger for a thermal capacity of 1.0 MW is to be erected upstream of the reheating furnace of a rolling mill fired by sulphur bearing coke oven gas. The energy for a pre-heating is taken from the skid rail cooling circuit which has a temperature level of maximum 90 deg. C