ENG. ANDREW OMWENGA
Chemical & Process Simulation Engineer • Thermodynamic Specialist
Green DRI Transition — Hydrogen Decarbonization & Techno-Economic Decision Intelligence
Section 1.0 — Simulation & Facility Metadata
Section 2.0 — Executive Summary
Aspen Plus process simulation and digital decision-support platform evaluating 5 progressive hydrogen transition pathways (NG100 → H25 → H50 → H75 → H100) for a 119 t/h metallic iron plant, optimizing trade-offs between process CO2 abatement, electrolyzer MW scale-up, renewable power tariffs, and capital investment constraints.
Section 3.0 — Problem Statement & Operating Bottlenecks
Conventional ironmaking produces 7–8% of global anthropogenic GHG emissions due to coal/coke reduction in blast furnaces. While natural-gas DRI (NG100) improves reduction chemistry (Natural Gas → H₂ + CO → DRI), it still emits ~35 t/h of process CO2. Jumping immediately to 100% green hydrogen (H100) requires a massive 335 MW electrolyzer, 2.68 TWh/year of renewable electricity, 64.4 t/h of design water, and substantial CAPEX. Plant managers face a critical challenge: Net zero cannot be engineered as a single leap; facilities need a quantifiable, staged roadmap balancing carbon targets against capital and infrastructure limits.
Section 4.0 — Objectives & Rigorous Simulation Methodology
Rigorous Aspen Plus steady-state simulation coupled with Python decision-support optimization algorithms. Process modeling accounts for gas-solid shaft furnace reaction kinetics, reforming thermodynamics, gas preheating, and syngas recycling. Evaluated across 5 operating scenarios (NG100, H25, H50, H75, H100) maintaining 119 t/h metallic iron output with 94%+ metallization.
Section 5.0 — Simulation Results & Thermodynamic Findings
The transition to green steel is an investment and infrastructure optimization problem, not merely a process chemistry question. Jumping straight to H100 creates an immense bottleneck (335 MW electrolyzer, 2.68 TWh/yr power demand). By modeling the journey (NG100 → H25 → H50 → H75 → H100), plant operators can phase capital allocation. Under typical grid constraints (e.g. 200 MW max power), H50 delivers 50% carbon reduction at manageable capital risk, paving the way for H100 when renewable power generation and grid capacity mature.
Section 6.0 — Core Engineering Takeaways
Section 7.0 — Model Assumptions & Future Recommendations
Model assumes steady-state shaft furnace operation with uniform iron ore pellet metallization (>94%). Intermittent renewable power supply was modeled based on average levelized cost and battery buffer storage baselines.
Integration of dynamic hydrogen blending kinetics in Aspen Plus Dynamics and downstream Electric Arc Furnace (EAF) continuous hot-charging thermal optimization.
Section 8.0 — Consultant Conclusion & Verification Sign-off
The transition to green steel should not just be promised; it should be engineered. Integrating Aspen Plus process simulations with a dynamic techno-economic decision-support tool empowers industrial leadership to move from vague net-zero ambition to actionable, plant-level engineering and investment roadmaps.
