Computational Fluid Dynamics Study of the Thermochemical Behaviors in an Ironmaking Blast Furnace with Oxygen Enrichment Operation

Abstract

The ironmaking blast furnace (BF) is an energy-intensive process, requires a considerable amount of carbon-related materials such as coke, coal, or natural gas, and releases enormous amounts of greenhouse gas (GHG). The oxygen enrichment operation is one promising technology to reduce the carbon footprint in the ironmaking process. However, the oxygen enrichment ratio (OER) varies significantly in practices, and the proper one is still unclear, especially in terms of fuel rate saving and in-furnace phenomena. In this study, a multi-fluid BF model is used to quantitatively study the influence of oxygen enrichment on the BF process in terms of bosh gas volume, top gas composition, and inner thermochemical behaviors of solid–gas–liquid phases. Under the simulation conditions, the results show that for every increase of OER, the blast rate is decreased by ~ 85 m3/min and nitrogen content in reducing gas is decreased by ~ 1.13 pct; also, the top gas temperature is lowered by ~ 17 K, and the flame temperature is increased by 58.4 K. Descending of cohesive zone (CZ) inside the BF is observed with the region volume ratio decreased by ~ 0.102; the chemical reserve zone of wustite becomes much narrower and lower inside the BF, but does not disappear. The potential of carbon footprint mitigation in the BF process is discussed with the optimal OER recommended, 7.5 pct under the present simulation conditions. This model can help to build a comprehensive understanding of the fuel rate saving and CO2 emission reduction of a BF adopting an oxygen enrichment operation.