Numerical Analysis on Effect of Areal Gas Distribution Pipe on Characteristics Inside COREX Shaft Furnace

Abstract

In recent years, two parallel pipes of areal gas distribution (AGD) were installed into the COREX shaft furnace to improve the furnace efficiency. A three-dimensional mathematical model at steady state, which takes a modified three-interface unreacted core model into consideration, is developed in the current work to describe the effect of the AGD pipe on the inner characteristics of shaft furnace. The accuracy of the model is evaluated using the plant operational data. The AGD pipe effectively improves the uniformity of reducing gas distribution, which leads to an increase in gas temperature and concentration of CO or H2 around the AGD pipe, and hence it further contributes to the iron oxide reduction. As a result, the top gas utilization rate and the solid metallization rate (MR) at the bottom outlet are increased by 0.015 and 0.11, respectively. In addition, the optimizations of the flow volume ratio (FVR) of the reducing gas fed through the AGD inlet and the AGD pipe arrangement are further discussed based on the gas flow distribution and the solid MR. Despite the relative suitability of the current FVR (60%), it is still meaningful to enable a manual adjustment of FVR, instead of having it driven by pressure difference, to solve certain production problems. On the other hand, considering the flatter distribution of gas flow, the higher solid MR, and easy installation and replacement, the cross distribution arrangement of AGD pipe with a length of 3 m is recommended to replace the current AGD pipe arrangement.