Green steel: Review of phase 1 of the injection trials

Hydrogen instead of carbon. Just over a year has passed since the world premiere of the use of hydrogen in ongoing blast furnace operations. What has happened in this first phase of the trials? We provide an overview.

On November 11, 2019, the steel world looked to Duisburg. Shortly after 12 pm the world’s first tests on the use of hydrogen in ongoing blast furnace operations started at the thyssenkrupp Steel plant site. The long-term goal: the transformation to climate-neutral steel production. The first phase of the tests has now been completed. We spoke to the experts about the results of the intensive practical tests.

Industrial pioneer in climate protection with hydrogen

In blast furnaces, coal dust is normally injected as an additional reducing agent. In blast furnace 9 at thyssenkrupp Steel, hydrogen is to take over this role in the future. An important step toward reducing CO2 emissions in steel production and protecting the climate. What have the experts learned about the new process in the first phase and what is the next step in the trials?

“The process will not change anything in terms of the quality of our pig iron,” knows Dr. Arnd Köfler, CTO of thyssenkrupp Steel. He sees the company as an industrial pioneer in climate protection. By 2050, complete steel production is to be climate-neutral and then based on direct reduction with hydrogen. This will require the construction of new facilities to replace the blast furnaces in the future.

The use of hydrogen in existing blast furnaces can already make initial contributions to climate protection. To ensure that this succeeds on an industrial scale, the company has mainly researched the technical feasibility in the first phase and learned a lot about the behavior of the plant technology.

Practical tests confirm simulations

The first phase involved blowing in hydrogen at one of the 28 blow molds of blast furnace 9. At the beginning there were short intervals, which were steadily extended in the course of the tests – from an initial few hours to up to 24. “The results confirm our simulations,” says Dr. Arnd Köfler. “At the same time, we have entered new technological territory here. We have to continuously analyze and evaluate the operating sequence in order to target the expansion of the tests.”

Thanks to continuous data collection and analysis during the tests, some of which lasted 24 hours, the team was able to gather a wealth of information, for example on the positioning of the hydrogen lance in the furnace, the flow and pressure conditions, and the interactions between higher temperatures and plant technology. The data collected was used to optimize the hydrogen technology with each subsequent test. The targeted injection volume of around 1,000 m³ of hydrogen per hour was also achieved during the trials.

In the second trial phase, the tests will be extended to all 28 blast molds in the blast furnace to pave the way for industrial use. Research will then focus on the influence of hydrogen technology on metallurgical processes in the blast furnace. The second phase is scheduled to start in 2022, somewhat later than originally planned due to the Corona pandemic. While the hydrogen for the first trial phase was still supplied by truck, the quantities required for the second phase make a pipeline necessary.