Effective Use of Available Heat for Maintaining a High Green Pellet Temperature

Abstract

In iron ore pellet production, an increased green pellet temperature has a positive influence on the straight grate induration furnace. Previous studies show that this can lead to both higher production capacity of the induration furnace and also reduced specific oil consumption. The aim of this study is to apply the process integration concept to analyze how to maintain a high green pellet temperature by using the available heat more effectively. The heat is today used for the indoor climate and is delivered by electricity boilers and a waste heat recovery boiler that is installed next to the induration furnace, using hot gases from the furnace to heat water. This work will however assume that one can use the heat from the waste heat recovery boiler to preheat the material stream. By optimizing the cold section of the pelletizing plant, using process integration and the mathematical modeling approach in combination with the newly developed Optimal Solution Space Method, the results show that it is possible to increase the green pellet temperature and also reduce the energy cost by using the available energy in a more efficient way. It is also showing that by retrofitting the system so that the waste heat from the waste heat recovery boiler is used to preheat the material stream, this also leads to reduced energy cost and also increased production of iron ore pellet since the temperature of green pellet will be higher.