Heat from the tunnel furnace was used to preheat the furnace trolleys, which reduced the consumption of gas by the burners installed on the furnace. The design concept was to build a closed canal with two locks for a dozen or so trolleys, located between the entrance to the furnace and the loading of the raw material.
Exhaust gases from the tunnel furnace, which come through the heat exchanger, heat the air, while the air is further transported to the duct made from the laminar panels. The warm air flowing through the loaded trolleys increases their temperature, which will reduce the amount of gas consumed by the burners in the heating zone. The safety bypass, controlled by throttles, will be installed- it will direct the exhaust gases towards the chimney, in case the exchanger is off. In addition to recovering heat from the exhaust gases for the purpose of heating up the trolley, it is possible to use a part of the air stream recovered from the wagons (decreased by the amount of heat intended to fuel the burners). In this case, the total heat power which can be achieved amounts to 464.07 kW.
The additional advantage of this solution is the ability to direct warm air from the trolleys towards the space above the dryer, which will improve the efficiency of the pre-drying process of the raw material.
Due to the modernization, 4.09 GWh of energy was saved and the cost-cutting reached the level of USD 188 thousand, with investment expenditures of about USD 286,000.00.