Nucor Steel employs the latest technological advances including electric arc furnaces run by production and performance management solutions from AVEVA
Berkeley, South Carolina - Since ancient metal workers first created it by removing nearly all of the impurities from iron at least 3,000 years ago, steel has had a profound impact on civilization. From the hand-forged weapons that gave tribal leaders a dominant advantage over their bronze-equipped neighbors, to the mass-produced railway lines and trains that drove the industrial revolution that forged the world we live in today, the common critical ingredient has been steel. Though the importance of this iron/carbon alloy hasn’t changed, the way we produce it has been revolutionised over decades.
"We live in a worldwide economy now,” said Dennis Boyd, of Nucor. “So it’s important that we stay on the leading edge of technology, both in how we control our furnaces and in how we collect data from them.”
As supervisor of the melting area electrical systems at Nucor’s mill in Berkeley, South Carolina, Boyd helped revamp the mill’s control systems with an AVEVA solution. With competitive pressures growing in the global steel market, Boyd and his colleagues wanted to make sure they were getting as much capacity as possible from their operation and solidifying the company’s market position.
The melting area of a steel mill is one of the harshest industrial environments in the manufacturing world.
As temperatures soar to 3,000 degrees Fahrenheit – almost one-third of the surface temperature of the Sun – and raw materials measured in the hundreds of tons are manipulated, an incredible strain is placed on equipment and control systems.
The majority of the world’s carbon and alloy steel production uses electric arc furnaces, which are fired primarily with scrap steel. At Nucor’s Berkeley mill each load consists of 180 tons of metal, about 80 percent of which is recycled scrap. Once charged into the furnace, an intensely enormous amount of energy – 1,200 volts and 160,000 amps – is added, generating enough heat to melt the charge. Impurities float to the top and are removed, leaving 165 to 170 tons of pure liquid metal. Carbon and alloys are then added to the mix to add tensile quality and produce the required grade of steel. Once it’s determined to be perfect, it’s transferred to the casters where it’s molded into sheets of differing thicknesses and widths to meet specific customer orders.
Flexibility in this environment is a key challenge as equipment disruptions occur frequently and components must be replaced often.
The organization must also be prepared to respond to rapidly changing market conditions. By providing a clear picture of what’s happening within the process, AVEVA delivers this flexibility.
“One of the issues we deal with a lot is the rapid changes we need to make,” said Mike Higgins, Level 2 Automation Engineer, Nucor Steel Berkeley. Throughout the implementation of the new system Higgins was responsible for programming PLCs and managing the supervisory control system. “Our mill is dynamic, our company is dynamic and our shop is dynamic. We are always trying to make changes to improve our process and we needed a system that would allow us to do that as quickly as possible. The less time we spend doing programming allows us to spend more time doing improvements and raising our total profits for the company.”
According to Higgins, the Berkeley mill has relied on the AVEVA industry-leading InTouch supervisory control and visualisation software since it opened in 1997.
But by 2002, the mill had outgrown the trending and analysis capabilities of the existing InTouch application and needed to take its data collection and analysis efforts to the next level. With the need for an advanced trending tool to help identify and eliminate problems that caused downtime becoming acute, Nucor managers turned to AVEVA Southeast and asked for a better way to collect and trend data.
The only caveat was that the new system had to work with the AVEVA applications the mill already had in place.
And it had to deliver a thin client that could withstand the extreme nature of the production floor. AVEVA Southeast suggested updating and building on the InTouch application already in place with Historian and System Platform.
The Historian puts the intelligence in AVEVA plant intelligence solutions, delivering the data – both current and historical – that empowered the melt shop team to do the detailed analysis and trending and has enabled them to identify and eliminate the problems that cause downtime.
Of particular value to Nucor Steel Berkeley, the AVEVA System Platform allows the use of standardised application objects for faster engineering. This means that new equipment can be added or removed from the mix easier than ever before. In an environment like the melting area of a steel mill, where equipment has a short life-cycle, this is of critical importance.
“Before we got up and running with AVEVA System Platform and the Historian, it would take days to add a new piece of equipment to the control system,” Higgins said. “Now I can do that in a matter of minutes.”
“One of the biggest benefits we saw was the elimination of downtime,” Boyd said. A common problem experienced in the melting area involved errors in the melt process that resulted in holes being burned in the sidewalls of the furnaces or the roof over them. These holes can be caused by a number of different failures, including an arc deflection, an arc flare or blowback from a co-jet, which blasts pure oxygen into the reaction to increase the temperature. Each of these errors causes the energy that should be passing through the scrap steel charge to be directed at the sidewall, blasting a fissure that will take hours, and possibly even days, to repair.
“We use sensors to track the temperatures on the side of the furnace,” Boyd added. “We were able to collect and track this much more accurately and come up with more sophisticated control processes.
"Specifically, this enabled Nucor to do two things: to alarm and shut down before we got holes. The occurrence of these holes has all but been eliminated since operators receive enough data from the system to analyse and identify trends. This has saved 2-5% in productivity just through elimination of downtime.
"It also allowed us to implement more advanced controls where rather than shutting the furnace off we can just volt the furnace down. That gave us a 5-10% gain in average voltage, which is directly proportional to productivity.”
Reduced downtime and increased productivity was only the start of the benefits experienced by Nucor Berkeley following the implementation.
The new system has also had a dramatic impact on the quality of daily executive reporting. Prior to deploying the new system, operations data was fed directly from the PLC’s on the shop floor into the centralised plant-wide data control system where a custom ‘C’ application would retranslate it into the database. This meant that three disparate sets of the data were required, and they weren’t always consistent.
Thanks to AVEVA, Nucor Steel Berkeley is doing this more efficiently and profitably than ever before.
Thanks to the AVEVA System Platform, Mike Higgins and his team were able to completely bypass the old system and feed data directly from the InTouch control system into the Historian and then into the plant-wide data collection system.
Metrics from the day-to-day operation, such as the number of tons charged into each load, the temperature in the furnace, and the amount of time the furnaces take to operate are collected and analysed each day to identify opportunities to improve processes. With AVEVA System Platform, managers are confident that the information they are working from is accurate.
“The Historian is something we’d been looking for,” Higgins said. “We had gotten to the point where we knew we needed to make improvements to our data collection and analysis. We would visit other mills and we were way behind what other people were doing, and now we are light years ahead. We went from being the butt of the spear to being the tip of the spear.
“Almost immediately after introducing the AVEVA Historian, we were able to see rapid, immediate feedback on our data and processes."
Nucor Steel started by collecting failure data, but over time has been able to use that as a basis allowing operators to trend failures. This enables them to predict when failures will occur and schedule preventive maintenance to minimize downtime.
They are also able to track what happens at each step in the production process, sampling the steel at different stages to make sure each batch is going to meet the grade and quality demands of their customers.
Each year the Nucor Steel mill in Berkeley, South Carolina produces more than 2,500,000 tons of rolled sheet steel and 1,000,000 tons of steel beams and girders in 20 different grades, depending upon the customer’s requirements. The steel is then shipped to customers who either reprocess it and resell it, or turn it into finished goods such as refrigerators and automotive parts.
“The steel industry is a very harsh environment,” said Boyd. “Everything is temporary. Nothing is permanent. We see equipment destroyed and replaced on a daily basis. And we needed a system that would enable us to make those changes without reinventing the wheel on a daily basis. AVEVA delivered that system and I would recommend it to anybody who is looking for a way to improve their process, speed up programming changes and increase profits.”