Original Article

Hydrogen intensified synthesis processes to valorise process off-gases in integrated steelworks

¹ Scuola Superiore Sant’Anna, TeCIP Institute – ICT-COISP, Via Moruzzi 1, 56124, Pisa, Italy
² K1-MET GmbH, Stahlstraße 14, 4020 Linz, Austria
³ Friedrich-Alexander-Universität Erlangen-Nürnberg, Chair of Energy Process Engineering, Fürther Str. 244f, 90429 Nuremberg, Germany
⁴ Montanuniversität Leoben, Chair of Process Technology & Industrial Environment Protection, Franz-Josef-Str. 18, 8700 Leoben, Austria
⁵ Air Liquide Research & Development, Innovation Campus Frankfurt, Air Liquide Forschung & Entwicklung GmbH, Gwinnerstraße 27-33, 60388 Frankfurt, Germany
⁶ Chemical Process & Energy Resources Institute, Centre for Research, Technology Hellas, 6th km Charilaou-Thermi Road, 57001 Thessaloniki, Greece
⁷ Voestalpine Stahl GmdH, Research Development Ironmaking Technical Department Business Unit Slab, voestalpine-Strasse 3, 4020 Linz, Austria
⁸ Central Mining Institute, Plac Gwarkow 1, 40-166 Katowice, Poland

^* Corresponding author: e-mail: i.matino@santannapisa.it

Received: 27 May 2023
Accepted: 31 July 2023

Abstract

Integrated steelworks off-gases are generally exploited to produce heat and electricity. However, further valorization can be achieved by using them as feedstock for the synthesis of valuable products, such as methane and methanol, with the addition of renewable hydrogen. This was the aim of the recently concluded project entitled “Intelligent and integrated upgrade of carbon sources in steel industries through hydrogen intensified synthesis processes (i³upgrade)”.

Within this project, several activities were carried out: from laboratory analyses to simulation investigations, from design, development and tests of innovative reactor concepts and of advanced process control to detailed economic analyses, business models and investigation of implementation cases.

The final developed methane production reactors are, respectively, an additively manufactured structured fixed-bed reactor and a reactor setup using wash-coated honeycomb monoliths as catalyst; both reactors reached almost full CO_x conversion under slightly over-stoichiometric conditions. A new multi-stage concept of methanol reactor was designed, commissioned, and extensively tested at pilot-scale; it shows very effective conversion rates near to 100% for CO and slightly lower for CO₂ at one-through operation for the methanol synthesis.

Online tests proved that developed dispatch controller implements a smooth control strategy in real time with a temporal resolution of 1 min and a forecasting horizon of 2 h. Furthermore, both offline simulations and cost analyses highlighted the fundamental role of hydrogen availability and costs for the feasibility of i³upgrade solutions, and showed that the industrial implementation of the i³upgrade solutions can lead to significant environmental and economic benefits for steelworks, especially in case green electricity is available at an affordable price.