Modelagem e análise de transferência de calor de um resfriador de clínquer tipo satélite para forno de cimento

Abstract

Concrete, with its main component, the cement, is the most important material in constructions worldwide. For the manufacture of cement, the clinker is the major constituent and is manufactured in a process of pyrolysis in rotary kilns. Clinker coolers are equipment used after the kiln. Currently, Grate Cooler is the most used equipment in this process. However, the large number of plants from cement kilns with satellite (or planetary) coolers still installed justifies an analysis for improvement. It is considered an equipment of great potential for energy consumption reduction in the kiln process. This paper proposes studies using an integral formulation of a heat transfer model, defining an energy balance and the efficiency of the equipment. Special attention is given in the curtain heat transfer, external heat transfer by radiation and convection and internal heat transfer by radiation, including the effect of the humidity and suspension dust in the air. This work includes too the characterization of the clinker. In addition, new techniques and advanced methodologies were used, and part of the model was analyzed with computational fluid mechanics (CFD) and discrete element method (DEM). The model is compared with literature data and cement plant information. A sensitivity analysis of several variables of the model is also performed. It is shown that there are great benefits in modifying the rotation speed and the emissivity of material and the wall have no greater impact on model results. A proposal is presented for replacing lifters to gain energy efficiency of the equipment. It is assumed the possibility of clinker coolers gain in 80 kJ per kg of clinker, representing about 2.5% of fuel consumption in a cement kiln.