A Mathematical Model of The Raceway for Real time Application to an Operating Blast Furnace with Pulverized Coal Injection

Abstract

The iron making Blast Furnace is an embodiment of multitude of complex processes, which are coupled and interactive in nature. Pulverized coal (PC) has become an important auxiliary fuel for blast furnace operation since the technique of pulverized coal injection (PCI) was developed over the years. When pulverized coal is injected into blast furnaces through blowpipes and tuyeres, because of the reactions of devolatilization, gasification and combustion along with formation of unburned char, the coal becomes a veritable source of heat and a reductant in the raceway. For this reason, PC is extensively employed in blast furnaces to replace the expensive metallurgical coke as far as practicable. In essence; utilizing PCI also has the critical advantage of reducing the operation costs of blast furnaces and decreasing the emissions of carbon dioxide. In this study , a reduced order first principle based mathematical model of the raceway has been developed for real time application to an operating blast furnace with a provision of data input interface synchronized with the plant Distributed Control System(DCS) . The model is capable of prediction of the temperature and gas composition profiles of the raceway zone for both with and without pulverized coal injection (PCI) conditions. Influence of all the major operating parameters such as PCI rate, blast temperature, blast volume, oxygen enrichment and humidity on the raceway behaviour, namely, the gas thermal and composition profiles have been investigated. It has been observed that with increasing PCI rate on a fixed fuel rate basis, the maximum flame temperature decreases and the position of the maximum flame temperature tends to shift towards the tuyere nose. Effects of other process parameters on gas temperature and composition profiles have been extensively validated with plant observations and found to be in good agreement with model predictions. From an operational perspective, this model provides a virtual platform for the operator to visualize the raceway phenomena using the built-in graphical user interface (GUI) in a real time mode.