ABB control systems allow Tata Steel to use lower cost oxygen
23 August 2011
ABB control systems are helping Tata Steel cut the cost of iron production at its Scunthorpe plant by allowing it to use medium pressure oxygen in its blast furnaces.
Tata Steel’s Scunthorpe steel plant produces carbon steel by the basic oxygen method. The existing pressurised oxygen plant at Scunthorpe produced high pressure oxygen at 42 bar for steel production, whereas the three operating blast furnaces only require an 11 bar supply. Producing oxygen at 42 bar and then reducing it to 11 bar was not cost-effective and so Tata Steel looked for another solution.
The company, in partnership with BOC, built a new medium pressure oxygen plant on the site, together with a 4.5 km pipeline to serve the three blast furnaces. Each furnace can take up to 20,000 m3 per hour of oxygen to enrich its air supply at up to 11 percent by volume.
The three operating blast furnaces, known as Queen Bess, Queen Victoria and Queen Anne, have an individual control system, based on ABB Advant, ABB 800xA and MasterView respectively. These control systems were installed progressively over the lifetime of the furnaces as each was shutdown for maintenance. Queen Bess and Queen Victoria use Master AC450 controllers and Queen Anne has a mixture of AC450 and Masterpiece.
Gopal Chopra, ABB Project Manager says: “Each blast furnace already had an ABB AC450 controller. To allow the furnaces to use the medium pressure oxygen supply, we upgraded/expanded the controllers with new hardware and software and linked them by a Modbus serial link to a PLC, which collects data about the operation of the furnaces and provides information management and reports for all three. We also installed ABB S800 I/O, for the hardwired signals for each furnace.”
The three separate control systems allow the furnaces to work independently on different production cycles. The new medium pressure pipeline feeds the blast furnaces via a three way valve station. Control of the oxygen flow to each furnace is a complex interplay between the needs of the three units, with each furnace needing to react to the condition and oxygen demand of its counterparts. Both pressure line control and flow control are performed by the ABB controllers.
Developing the system threw up a number of challenges. To develop the software, ABB made use of its software specialists in India who have experience of control systems for the metals industries. Chopra says: “We found during testing on site that some of the EEPROMS needed changing as the new controller was not compatible with the existing system hardware. We have a policy of dealing with any such problems straight way and the customer was able to see that we addressed the issue promptly.”
Ian Render, Project Engineer with Tata Steel, says: “It is a very complex control system and everyone at ABB did a really good job. They were all very dedicated, from the software developers to the guys doing the commissioning on site.
“The result is a very good control system that allows us to make use of a lower cost oxygen supply route. Overall, the project has been a big success.”
The project was undertaken as part of ABB’s Evolution programme, under which ABB provides software updates following the initial installation.
ABB (www.abb.com) is a leader in power and automation technologies that enable utility and industry customers to improve their performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 130,000 people.
For more information, please contact Arlene Hutchinson
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