Successful Revamp

Dream Team for Steel Works

Continuity of oxygen supply was a must as the LINDE PLANTSERV^® team embarked on a revamp project at the Linde Gas site in Linz, Austria. Rising to the challenge, the team seamlessly integrated the two new oxygen compressors thanks to smooth teamwork, flexible job sharing across teams, and the excellent relationship with voestalpine Stahl GmbH.

• In Linz, Austria, Linde Gas replaced four old oxygen compressors with two new ones to ensure that voestalpine Stahl GmbH would continue to enjoy reliability of supply.
• LINDE PLANTSERV was responsible for the entire engineering, procurement and construction of the compressors as well as the subsequent startup phase.
• During the project, the steel works could rely on a steady stream of oxygen with no interruptions to operational continuity.

Blast furnaces are the birthplace of steel. These giant chimneys, which can stretch up to 90 meters towards the skyline, transform iron ore into pig iron in a series of process steps that require temperatures as high as 2,200 degrees Celsius. Crude steel is then produced in the converter through oxidation. Steel manufacturers like voestalpine Stahl GmbH, based in Linz, Austria, require gaseous oxygen for both processes. Oxygen needs to be injected into the furnaces in order to achieve the high temperatures required. The gas also removes impurities from the pig iron. Linde Gas’ job is to provide voestalpine with a reliable, non-stop supply of oxygen. Linde Gas operates one of Europe’s largest gas production hubs at the voestalpine site. Several air separation units (ASUs) generate oxygen, nitrogen and argon at various pressure stages here. “The steel works is our main consumer of oxygen,” explains Wolfgang Suchanek, Head of Production at Linde Gas GmbH Austria. “We use multiple compressors to bring the oxygen to the required pressure of 25 bar. Last year, we had to replace four end-of-life compressors. In the process though, we had to avoid any interruptions to the oxygen supply for the steel works.” That is the greatest challenge in revamp projects where reliability of supply has to be maintained. In order to guarantee this, Suchanek worked with voestalpine’s decision-makers to sketch out various scenarios that would strike an optimum balance between cost-effectiveness and security of supply.

Market Insights Help Monetize Old Assets

As early as the bidding stage, the Linde Gas team turned to their Engineering colleagues for advice on where to best connect the two new compressors to the existing piping system. No new plot space was available, so the four existing compressors had to remain operational for as long as it took to build and commission the two new ones. Downtime was not an option. Other factors to be considered by the Linde experts in the choice of location were ease of connection to the existing electricity supply and cooling water systems. The team eventually decided in favor of an old machinery building. However, it already contained two back-up ASUs that had been installed around 20 years ago to guarantee a non-stop supply of nitrogen for voestalpine. “The two units had only clocked up around 1,000 hours of operation, so they could easily be relocated for several more years of useful service. Thanks to the market insights of our LINDE PLANTSERV colleagues, we quickly found a new home for the ASUs,” recalls Suchanek, while Kelbch added: “We knew that a different chemicals location needed two plants, so we were able to sell the ASUs on to that customer. It was a real bonus that the Linz project led directly to a follow-up engagement for us.” The engineering expert and his team reconditioned the plants for the new operator and installed them at the chemicals site.

Key to Success: Smooth Job Sharing Across Team

The two new compressors required for the Linz location were piston models. These machines are known to produce considerable levels of vibration while in operation. In order to identify and counteract any negative impact on the surrounding equipment and adjacent office space at an early stage, LINDE PLANTSERV carried out appropriate safety and stability tests. Their analysis convinced the plant experts that no additional structural work would be required after commissioning. The results did, however, show that the machines would need a few modifications but Kelbch was able to implement these within schedule.

“In addition to all this, we had to submit plans to the relevant authorities setting out the structural engineering safeguards we would put in place for the compressors, due to the fact that compressed oxygen is highly flammable,” Kelbch continues. One example was the fire containment enclosure, with its removable covers, which must comply with European Industrial Gases Association (EIGA) guidelines. The Linde Gas team provided sterling on-site support when it came to liaising with the local authorities as well as with the Linz municipal fire department and voestalpine’s own fire service. This enabled early identification of the regulatory requirements that would need to be factored into the engineering plan. “Given that the location in Linz has been established for several decades now, we were able to bring a wealth of experience to the table, which undoubtedly contributed to the smooth execution of this project,” pointed out Suchanek. Summarizing the secret to success, he says: “Throughout the entire process flow, we were always able to find the best possible job sharing model across the LINDE PLANTSERV and Linde Gas teams.”

Room for Flexibility Despite Tight Schedule

The project’s positive outcome is also attributable to the precise planning and smooth dovetailing of the individual steps. The Linde Engineering team had, for instance, no more than six hours to integrate the new compressors. During this key step, the two new compressors were connected to the existing piping network. “Our work actually coincided with a peak production window at the steel works,” explains Kelbch. “We had a very narrow timeframe to ensure safe working conditions while completing all the required tasks within the tight schedule we had been set.” What this meant in practice was that the existing line was isolated and the new connection was inserted with a crane and welded on. After that came cleaning and multiple inspections of the joined piping to pave the way for the commissioning stage.

Both Linde Gas and Linde Engineering share the view that this was an exemplary flagship project. “We had the perfect partner for flexible execution of this revamp engagement. There was minimal disturbance to the site’s operations – and we continued to provide voestalpine with a reliable and steady supply of oxygen,” comments Linde Gas expert Suchanek. “The outstanding collaboration between both teams was the key to our success,” adds his engineering colleague Kelbch. “We have seen yet again that every revamp job is unique, and that it ultimately pays off to listen carefully to your customer and partner requirements and factor them into your planning right from the beginning.”

The two new compressors for Linde Gas have been in operation at the voestalpine Linz site since 1 May 2019, providing a reliable stream of compressed oxygen for steel manufacturing.