ABSTRACT

Presently, blast furnace-basic oxygen furnace (BF-BOF) route is conventionally used in integrated steel plants (ISPs). As availability and cost of coking coal are becoming serious issues, alternative routes of iron and steel production such as COREX, shaft-based process for direct reduction of iron and electric arc furnace in combination with BF-BOF route is becoming a matter of focus. The possibility of energy efficiency improvement using such a mixed route in ISPs is dependent on proper utilization of fuel gases generated in addition to the total input fuel bearing resources to the plant. A flow-sheet simulation approach has been developed using phenomenological and stoichiometric modeling of the important process steps. Optimization for lowering input fuel energy and maximizing available fuel gas energy has been developed based on evolutionary algorithms using simulated flow-sheet streams. The fuel gas used downstream needs to be tailored to higher calorific values (CVs) in the gas network for critical downstream applications. Two cases of high CV-mixed fuel gas have been considered comprising (a) principally mix of coke oven gas and COREX off-gas and (b) mix of blast furnace gas and coke oven gas in 2:1 volume ratio along with high CV gases such as COREX off-gas and BOF converter gas. Energy optimization possibilities exist which simultaneously minimize input fuel energy and maximize high CV fuel gas for downstream use. The flow-sheet solutions simultaneously lead to configuration predictions with fractional stream splits.

摘要

目前，综合钢厂（ISP）通常采用高炉-碱性氧气炉（BF-BOF）路线。随着炼焦煤的可用性和成本成为严重问题，COREX、竖井直接还原铁和电弧炉等钢铁生产替代路线与高炉-转炉路线相结合正成为关注的焦点。在 ISP 中使用这种混合路线提高能源效率的可能性取决于对产生的燃料气体的适当利用，以及对工厂的总输入燃料承载资源。使用重要工艺步骤的现象学和化学计量模型开发了一种流程模拟方法。基于使用模拟流程流的进化算法，已经开发了用于降低输入燃料能量和最大化可用燃料气体能量的优化。下游使用的燃料气体需要根据气体网络中较高的热值 (CV) 进行调整，以用于关键的下游应用。已经考虑了两种高 CV 混合燃气的情况，包括 (a) 主要是焦炉煤气和 COREX 尾气的混合和 (b) 高炉煤气和焦炉煤气以 2:1 的体积比以及高 CV 的混合COREX 尾气和 BOF 转炉气等气体。存在能量优化的可能性，其同时最小化输入燃料能量并最大化下游使用的高CV燃料气体。流程解决方案同时导致具有分数流拆分的配置预测。