Optimization of Hydrogen Valorization in a Steelworks Blast Furnace Gas Stream

Thesis Abstract

This study addresses the challenge of maximizing hydrogen valorization from a steelworks blast furnace gas (BFG) stream by optimizing gas cleaning, reforming, and energy recovery processes to enable low-emission, high-efficiency syngas supply for downstream applications. The aim is to develop an integrated valorization framework that increases hydrogen yield, improves process energy efficiency, and minimizes CO2 emissions within an operational steelplant environment. Specific objectives include (1) characterizing the composition and variability of BFG in a mid-size integrated steel plant, (2) evaluating pretreatment and purification options for selective hydrogen recovery, (3) assessing catalytic reforming and membrane-based separation configurations using process simulation and pilot-scale validation, (4) optimizing process conditions through multi-objective optimization to maximize hydrogen recovery while minimizing energy consumption and capital cost, and (5) conducting a techno-economic and environmental impact assessment to quantify lifecycle benefits and risks. The methodology adopts a mixed-methods approach anchored in systems engineering and chemical process optimization. The study population comprises the BFG from a 2.0 Mt/year basic oxygen furnace route, with data collected from continuous gas composition monitoring over six months (n = 1800 hourly samples) and from a concurrent pilot-scale test rig featuring a staged water-gas shift reactor, preferential CO2 removal, and a high-temperature polymer electrolyte membrane (HT-PEM) module. Data collection instruments include on-line gas analyzers (FTIR, GC-TCD, and H2/CO detectors), mass spectrometry for trace species, and flow meters, complemented by material and energy balances from the pilot unit. The analytical framework employs regression analysis to correlate BFG variability with process performance, ANOVA to evaluate the significance of treatment configurations, and multi-objective optimization (genetic algorithm coupled with Aspen Plus simulations) to identify Pareto-optimal operating points. Process reliability and sensitivity analyses are conducted via Monte Carlo simulations to capture uncertainty in gas composition and demand. Theoretical grounding integrates the Hydrogen Economy framework and the Resource-Based View to analyze capability development in process integration, with reference to the Porter’s Five Forces for economic viability. Key expected findings include quantified hydrogen recovery potential from BFG under varying process configurations, identification of the most cost-effective combination of pretreatment (particulate removal and sulfur species mitigation), reforming (steam reforming versus dry reforming pathways), and separation (membrane selectivity vs. pressure swing adsorption) technologies, and the determination of optimal heat integration strategies that reduce external energy input by at least 18%. The study anticipates a robust techno-economic model demonstrating a net present value positive operation within a 10-year horizon at current hydrogen and natural gas price projections, with a break-even capital cost threshold defined for the pilot-scale retrofit. Environmental outcomes are expected to reveal a substantial reduction in CO2-equivalent emissions, driven by hydrogen-rich syngas production and improved energy recoveries, quantified through a cradle-to-gate lifecycle assessment using the ReCiPe method. Contribution to knowledge includes (i) an integrated, plant-specific valorization framework translating blast furnace gas into a high-purity hydrogen stream with practical retrofit steps, (ii) a validated multi-scale model linking BFG composition dynamics to downstream reforming and separation performance, (iii) a decision-support tool delivering operational guidance and capital expenditure estimates for steelplants pursuing hydrogen valorization, and (iv) empirical data on the performance and reliability of HT-PEM modules in high-impurity syngas environments. The main conclusion is that a carefully staged integration of gas cleaning, catalytic reforming, and selective separation can unlock substantial hydrogen valorization from BFG with favorable economic and environmental outcomes, provided that process control is harmonized with heat integration and market signals. Recommendations include implementing a phased pilot-up, prioritizing feedstock stabilization to reduce sulfur and particulates, adopting a modular HT-PEM separation architecture, and establishing a real-time optimization dashboard to sustain Pareto-optimal operation under dynamic plant conditions.