焼成および非焼成ペレットを使用した還元鉄製造プロセスのエクセルギー評価

抄録

In order to make a clear evaluation of overall energy requirement for the production system of directly reduced iron through pellet from iron ore powders, exergy analysis was applied to the two systems. The first one consists of pelletizing, firing and reduction processes (Fired pellets method) and the second one includes pellets curing process instead of firing process (Cement bonded pellets method).
Being compared with enthalpy balance, exergy analysis has two advantages in that the exergy expresses the quality of energy and evaluates different kinds of energy like chemical, thermal, pressure, mixing energies and so on by a unified measure.
As a result of exergy analysis, fired pellets lose less exergy than cement bonded pellets in the reduction process in a shaft furnace. As the overall system, however, exergy requirement in the cement bonded pellets method is about 50% of that in the fired pellets method. This marked difference is caused by the large exergy loss in the firing process. Furthermore, exergy loss in the production of cement bonded pellets will be decreased by decreasing the amount of cement added as binder.