EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

Pulverized coal injection (PCI) is now commonly used in iron making blast furnaces to produce reductants and to generate heat in the raceway. The advantage of using this important auxiliary fuel is that it replaces the expensive metallurgical coal and, therefore, helps in lowering the operating cost of the blast furnace. The optimization of the PCI practice has led to high rates of pulverized coal injection in some furnaces. Moreover, natural gas has also been used as an additional auxiliary fuel, but its effect on the coal burnout is not very well understood yet. In this paper, a three-dimensional CFD model is described and used to simulate the trajectory and combustion performance of pulverized coal particles injected into the raceway of a blast furnace. The numerical results were first validated by comparison to an experimental setup, in which five different industrial coals are burnt in an environment with conditions close to those found in the raceway. After validation of the model, a detailed investigation in an actual blast furnace raceway is then conducted to optimize the coal burnout with high PCI rates and/or natural gas injection. Process parameters, types of coals and lance design represent the main aspects that were studied.