Tata Steel Limited's Blast Furnace No. 5 in Port Talbot, UK

Primetals Technologies had already become a proven supplier to Tata Steel during the rebuild of the No. 4 blast furnace in 1992 and essentially reverse-engineered this design to rebuild blast furnace No. 5 in 2003. This rebuild in 2003 proved to be the world’s best time achieved for building a new blast furnace on an existing foundation.

Primetals Technologies was able to agree to the ambitious deadlines due to its familiarity with blast furnace No. 5.

The critical areas for achieving the desired campaign extension were highlighted as the following:

• Downcomer
• Furnace shell
• Hearth refractory

Downcomer

The downcomer was highlighted as a critical area due to concerns over the internal refractory and shell condition. A further complication was that a large section of the semi-clean gas main was supported off the downcomer. To ensure a good fit, the existing downcomer was surveyed extensively using 3D scanning equipment to determine its relative position and overall size. This information was then imported into modelling software, which was used to design the new downcomer. The new downcomer was pre-assembled on-site and lifted into position in one unit following the removal of the existing piece. The downcomer was then lined with refractory in situ to prolong its life. This required careful coordination with surrounding works in the gas cleaning plant. The planning and preparation that preceded the installation activity made a huge contribution to the success of its construction and reduced the schedule dramatically.

Furnace Shell

The belly area of the furnace was identified as a critical area as worn refractory had caused premature ageing of the shell in this location. As a result, a band in the belly area of the furnace was removed and replaced with new components, including new refractories. The removal and installation of the new shell was carried out during hearth clearance activities below, saving time but introducing risks that needed careful management. Other works included repairing the throat area and replacing instrumentation, damaged cooling elements, and the flexible piping between the cooling elements. These works were carried out both from outside the furnace and internally using a number of movable platforms inside the furnace.

Hearth Refractories

The hearth pad was identified as a critical area due to significant wear detected from the embedded thermocouples. A partial repair of the hearth area was carried out at the tapholes and the base of the hearth. This included the replacement of the embedded thermocouples and the external cooling system. The interface between the existing and new hearth refractory proved difficult, but the construction team managed the installation extremely well. The biggest challenge for this area was the uncertainty surrounding the condition and what would be found once access was gained to the furnace. As a result, at the design stage, many different possibilities were considered, and contingencies were incorporated into the design to enable flexibility.