Based in Saarland, Germany, Dillinger Hüttenwerke AG (Dillinger) is one of the world’s leading manufacturers of heavy plate products. The primary material required for this purpose; continuous cast slabs, are produced right here at the company’s Dillinger Hütte Steelworks. The construction of the new CC6 vertical continuous casting line, with an investment of around 400 million euros, is one of the largest single investments at the company’s Dillingen steel plant to date. A total of 4,500 workers spent more than five years building the new line, which officially debuted in July of this year. This facility takes steel slab production to entirely new dimensions: With a thickness of 300 to 500 mm, these are bound to be the thickest steel slabs worldwide, which will come in particularly handy for the construction of pipelines or wind turbines.
Extensive service package
Working under contract from the SMS Group, one of the worldwide leaders in metallurgical and rolling mill technology, ABB delivered an extensive service package. In addition to the hardware, this included engineering, project management, installation supervision, commissioning and on-call services. It features 75 operating stations for the System 800xA process control system alone, along with 1,200 graphics, over 110 systems and control cabinets, 20 controllers and 38 PROFIBUS lines. Add to that instrumentation for more than 550 pressure gauges, flow meters, temperature-measuring devices and 40 control valves. In terms of manpower, the project was no less extensive: “At peak times, we had 20 ABB team members in the test area programming the System 800xA control system with Melody PM876 for the whole site. Then, during commissioning, we had 35 ABB people on site,” says ABB project leader Jürgen Flothmann.
The plant’s in-house switching facility houses row after row of control cabinets on six levels: This is where all 25,000 signals of the facility converge through more than 500 kilometers (310 miles) of cable lines. “Our process control system is the nerve center of the facility, as it were. It analyses all of the signals and serves our operations personnel as the primary means of running the facility,” explains Jürgen Flothmann.
Focus on the basics
At the heart of the CC6 is a control station worthy of a small town police force: It has a whopping 26 monitors for the operator to keep track of the casting progress from every angle at all times. “Continuous casting is a complicated process. Even the smallest error can cause an interruption in the casting process with some very costly results,” comments Jürgen Flothmann. It is for this reason that process visualization is essentially very basic: while everything is shown in gray, any colors – say, red – are reserved for error messages. Here, the idea is to immediately draw the attention of operators to any sign of potential trouble without first being distracted by a multitude of other messages.
One of the main ingredients in steel production is water. To ensure the complete solidification of a cast strand measuring 17.5 meters (57.5 ft.) in length, it has to be cooled down with water using 776 nozzles divided into 19 control circuits. Contributing to the water supply are ABB instrumentation products like pressure gauges, flow meters and temperature-measuring devices.
Needless to say, a major milestone of the project was its first cast: In fall 2015, tests made on the CC6 led to the casting of the world’s largest and first slab measuring 500 mm thick – earning the Dillinger company a spot in the Guinness Book of World Records. The facility currently remains on a trial run under production-like conditions. Once it goes through the commissioning stage, Dillinger is ready to use this new facility to produce steel giants by the piecework: Production goals call for a casting output capacity of 200 slabs a day measuring up to 11,800 mm in length, 2,200 mm in width and 300 to 500 mm in thickness. One slab weighs as much as 120 tons – about as heavy as 24 elephants. Dillinger already has plans to deliver the slabs to their own rolling mills in Dillingen and Dunkirk, France.
CC 6 vertical continuous casting line
The process of continuous casting involves the casting of steel not in the form of blocks, but in the form of a strand. Due to its fluid core, the strand has to be cooled until it solidifies. Once solidified, the strand is cut to desired lengths by means of cutting torches or shears. That said, here‘s what makes the CC6 special: Usually, the vertically cast and still hot steel strand is bent horizontally prior to being cut into slabs. However, bending the steel strand impairs the quality of the steel. Unlike conventional facilities, the CC6 employs a new flame cutting machine in which the slabs are cut in a vertical position before being individually transported further down. An impressive tipper then places the cut slabs horizontally on transfer carts for further transport to where they are rolled into high-grade steel.
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