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Blast furnace goes digital - after 50 years of operation
Sweden
PROFIBUS PA

Project
SSAB Oxelösund with its two blast furnaces is the only integrated steel works in Sweden. Blast furnace 2 which has been in service for more than 50 years is now more modern than ever after being overhauled in 2006: Digital Profibus technology and some 400 PROFIBUS PA field devices (ABB) are now keeping a watchful eye on the production of pig iron – 24/7.

“The use of Profibus for this type of process was a pioneering achievement,“ proclaimed Sten Åhlin, Head of Electrical and System Design within the Metallurgy department of SSAB Oxelösund. “The furnaces generally have to be overhauled after eight years due to wear,” explained Sten Åhlin.“However, thanks to the new technology, which removes the need for prolonged stoppage times, we expect a service life of 15 years“. Communication between the field devices and the control system is now almost exclusively digital thanks to Profibus. “But the sensors in the furnace are of the same type as before,” said Sten Åhlin. “The difference lies in the transmitters, which now provide a digital value
instead of an analog one.”

Solution
SSAB Oxelösund carries out its modernization projects independently and also develops its own control system. Approximately 300 temperature transmitters, 50 flow transmitters and 50 pressure transmitters have been installed, all with a Profibus PA connection. That is about twice as many measuring points than in previous furnaces, giving the operator more information from the process. Assembly and final inspection were carried out by SSAB’s own equipment technicians. The Profibus solution has also helped speed up recommissioning following the overhaul of the furnace. More than two years have now passed since blast furnace 2 was commissioned and the fieldbus solution has been working like clockwork ever since.

Conclusion
“The modernization of furnace 2 worked extremely well,” confirmed SSAB project manager Björn Olsson. PROFIBUS and the new process devices (ABB) along with the other measures carried out are now intended to help keep the blast furnace in continuous operation for 15 years. This doubling of the operating time is to be achieved by being able to avoid prolonged interruptions to the cooling processes. It is also anticipated that it will be possible to carry out maintenance work in shorter cycles in future, as the process in the furnace remains active.