Estudo da relação entre os custos com energéticos em um forno de grelha móvel e o percentual de espaços vazios encontrados no leito de pelotas de minério de ferro

Abstract

The hardening furnace of raw pellets from Samarco SA, type the traveling grate also called Straight Grate, is used in the firing iron ore pellets inserted into the grate cars moving with a certain speed through heating zones. In this type of furnace, the pellets are heated predominantly by convection (FLAMANT et al., 1992) by heated gases byburners installed in the pre-burning and burning zones. The moving of these hot gases is performed by process fans making this fluid pass through the bed of pellets possible with appropriate conditions of speed, temperature press to drying, sintering and cooling of the pellets while they move inside the furnace. One of the most important parametersin this process is the permeability of the particle bed, which according to Ergun (1952), is a direct function of the voids formed by the particle packing, since these particles are homogeneously distributed in order to allow formation flow channels continuous, uniform and parallel. During this study on the evaluated plant, it was realized that how larger for the particle size range between 8 mm and 16 mm diameter of the raw pelletsinto grate food or more explained how much more homogeneous is the newly formed fixed bed the higher percentage of voids (%) found it. Through the control of this metric, the furnace process will respond with higher or lower consumption of thermal and electrical energy and also more or less productivity due to the physical quality change. As a result, this study aimed to show the importance of knowing all particle sizes and understand its influence on the percentage of voids map the occurrence of range of this factory floor indicator found and practiced in fixed beds in the iron ore pelletizing industry and, finally, understand the relationship of this metric with some operational control parameters and associate them with physical quality, productivity and cost of energy from the indication of an empirical model of cost control in an furnace type straight grade.