Bob Fish, plant engineer energy operations and fuel, said: “This three-storey boiler is huge – it’s the equivalent in size of 2.5 houses stacked on top of each other and contains thousands of tubes, totalling an astonishing 15,080 metres in length. These tubes are filled with water and four multi-fuel burners in contact with the tubes convert the water to steam. This is then used to generate electricity and is also used directly as steam across the site.
“Over time the tubes wear and this inevitably leaded to leaks that affect the boiler’s performance. This £3 million investment allowed us to change tubes totalling 12,000 metres length and a combined weight of 60 tonnes. We've now brought the boiler back on line and, thanks to the hard work and skill of all involved, it’s performing very well and providing a reliable service to the site.”
The project involved sourcing 76.1mm diameter steel tubes. The material used to manufacture the tubes has a chromium molybdenum addition and this helps improve corrosion resistance, extending the performance life of the tubes. Contractor Heathyards bent, shaped and welded the tubes off site and contract company Altrad Babcock then installed the new tubes, a task involving specialist equipment and a team of 50 that clocked up a total of more than 90,200 hours working on the project.
Process steam is used in a variety of applications including generation of electricity via turbines and creating the vacuum needed in secondary steelmaking operations at the Basic Oxygen Steelmaking plant, as well as providing heat to office blocks across the Scunthorpe site. “But none of this can happen without the works-arising gases,” said Fish. “The gases created in our operations, such as that at the blast furnaces, feed directly into what we do to create both electricity and steam.
“It all goes hand-in-hand – and by doing this, we can also generate savings for the business. With eight boilers in total on the Scunthorpe site, when all are operating fully we have the potential to save £13,500 an hour and can even bring in money to the business when excess energy is exported to the National Grid.”