An improved CFD-DEM modelling of raceway dynamics and coke combustion in an industrial-scale blast furnace

Abstract

The raceway dynamics and combustion by lateral injection of high-temperature gas into a packed bed of solid fuel are widely practised in various industries such as ironmaking blast furnace (BF), yet the particle-scale simulation and understanding were hindered by low resolution and huge computational cost. In this work, an advanced reactive computational fluid dynamics-discrete element method (rCFD-DEM) featuring two state-of-the-art techniques - coarse-grained method and smoothing method is developed to describe raceway dynamics and coke combustion in a three-dimensional (3D) industrial-scale BF. The model is validated against the measurements in the open literature. The simulation results show that the smoothing method can more reliably capture raceway morphology and the coarse-grained treatment reduces 78.14 % computational costs under the given conditions. The typical phenomena are illustrated in terms of raceway shape and size, temperature field and gas species distributions. Then, the effect of the key operating parameters is quantified in terms of raceway size, gas temperature and species distributions. The comparisons indicate increasing the blast rate from 2.78 Nm3/s to 3.05 Nm3/s and oxygen mass fraction from 0.17 to 0.27, the raceway volume expands by 61.11 % and 47.62 %, respectively; moreover, lower blast rate, higher bed temperature and higher oxygen mass fraction lead to higher temperature distribution and higher CO concentration. The present work provides a cost-effective tool for understanding and optimizing raceway operation in practical BFs.