SOTO Consulting Engineers recently partnered with BlueScope Steel (BSL) to replace a maintenance platform atop the gas bleeder flare stacks. These 85-metre-high flare stacks are iconic landmarks of the Port Kembla steel plant and integral to its blast furnace operations.
In blast furnace operations, iron ore is reduced to molten iron using coke as a reducing agent. This process produces blast furnace gas (BFG), a by-product consisting mainly of carbon monoxide, carbon dioxide, and nitrogen. Proper management of this gas is crucial to maintaining safety and operational efficiency.
The number 3 Excess Gas Bleeder, located at Blast Furnace 5, is used to flare off excess blast furnace gas produced by the blast furnace operation from the steelworks’ interworks gas distribution network. The bleeder is currently around 50 years old, having endured decades of relentless high temperatures, resulting in continuous maintenance challenges.
The bleeder is required to support the operation of either Blast Furnace 5 or 6, necessitating an extension of its operating life by around 25 years. To extend its operating life, the maintenance platform perched high atop the stack had to be replaced.
With a tight execution window during plant shutdowns and favourable weather needed, BSL project engineers decided to extend the stacks by 1.2 metres and place a new platform above the existing one. This strategic move allows for the future removal of the old platform, with the newly installed platform acting as a heat radiation shield.
SOTO Consulting Engineers were called on to design the new platform and meticulously plan its placement during craning. “Our design ensures the platform meets BlueScope’s operational load requirements,” said Marius Birsanu, SOTO’s Senior Design Engineer. “We also ensured that the entire structure, including the 1.2-metre extension, remains robust and stable.”
Integrating the new platform with its trio of stack outlets onto the existing infrastructure was a significant challenge. The engineers employed a sophisticated combination of multiple laser scans and point-cloud analysis to create an accurate 3D model of the existing stacks, enabling accurate design and fabrication of the new platform. This ensured a flawless interface with the existing flanges and bolt holes with millimetre precision.
“Wind presented a major challenge,” Marius said. “The 80-metre-high towers are prone to swaying in the wind, necessitating multiple laser measurements overlaid to construct a sufficiently accurate model. The platform was designed in three sections for ease of transport and on-site assembly. Each segment was bolted together, and the stack extensions were affixed to the existing flare stack headers.”
A precision jig was built during fabrication to replicate the structure, allowing for meticulous testing of the fit between the new platform and stack headers. This ensured exactness before installation, and on an exceptionally calm evening, the new platform was smoothly elevated and precisely positioned onto the flare stacks without encountering any issues.
