Steel Mill: Better Safety Through Wireless

Monday, October 11, 2010 @ 07:10 PM gHale

Through a wireless solution, Northstar Bluescope Steel improved its furnace control at its mini-mill in Delta, OH, resulting in a hike in production, a reduction in maintenance costs by $200,000 annually, and improved worker safety.
The self-organizing wireless network, based on the IEC 62591 (WirelessHART) standard, is able to collect data used to control the temperature of cooling panels and water-cooled burners on the mill’s electric arc furnace. This data is critical to safe furnace operation. Overheating cooling panels can lead to major furnace damage, with a blown-out panel costing as much as $20,000 to repair. Production time is also lost when the furnace must shut down during maintenance or repairs.
“Better temperature control through wireless has allowed us to add up to one additional batch per day,” said Rob Kearney, maintenance supervisor for Northstar Bluescope Steel. “With each batch worth as much as $200,000, that’s a significant advantage.”
This wireless program replaced a hard-wired monitoring network with hundreds of wiring junctions. The old network suffered frequent measurement failures in the mill’s harsh environment, with its high electromagnetic field, flying slag, vibration, moisture, and temperatures as high as 3,000 degrees Fahrenheit.
“Between nine and 12 measurements per week would fail due to high temperatures or physical damage to sensors, cable or conduit,” said Kearney. “And when a measurement point fails, the furnace must be shut down. The new wireless solution eliminated almost 100 percent of the cable and conduit, which reduced maintenance costs by $200,000 annually. The new wireless solution has been up and running for four months without a single failure.”
The wireless network includes 32 of Emerson Process Management’s Rosemount wireless temperature transmitters; 28 for control and four for monitoring. The transmitters send their data to a Smart Wireless Gateway, which interfaces with the mill’s transformer-regulation and burner-control system.
“Safety has also been improved,” Kearney said. “The furnace’s cooling panels are operating consistently at a safe temperature, and there is less maintenance required around the hot furnace shell, where ambient temperatures can be 140 degrees.”
Due to its success, Northstar Bluescope intends to implement a similar wireless solution for a second electric arc furnace.

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