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Going with the flow: upgrading the ventilation system for Australia’s largest aluminium smelter

Since its opening in 1983, the Tomago Aluminium plant has more than doubled their production output from 250,000 to 590,000 tonnes. Thanks to their multi-disciplinary capability, the Advitech Group have been able to advise on the various process engineering projects which have driven much of the mechanical and structural work required throughout these upgrades.  

Several years ago, Tomago Aluminium embarked on a major production upgrade projectnamed AP22, which ultimately resulted a re-engineering of the aluminium smelting process and a production increase from 250,000 to 530,000 tonnes. Over the course of several years,  Advitech’s process engineering department assisted with key aspects of the upgrade. 

One such aspect was a complete overhaul of the plant’s ventilation systems: the plant’s European smelter design had long struggled with the Hunter’s hot and humid climate, such that there were much greater volumes of smelter ventilation air needing to be treated by existing pollution abatement systems. In stepping up production, there was even greater pressure on these systems. 

There’s a direct linear relationship between the amount of metal produced and the amount of pollution put into the air – so we needed to pay a lot of attention to the impacts of AP22 on the existing systems so that environmental protection obligations were maintained,” explains Lead Process Engineer Carl Fung. “Essentially, the project called for major process engineering components within the smelter to be completely redesigned and recalibrated.  

Having worked collaboratively with the client for several years, Carl suggested they might resolve some of the smelter ventilation and pollution abatement issues with the assistance of his Advitech colleagues from the Hushpak team

“With their help, we were able to fabricate and construct a 1:1 scale model of a smelter pot; a critical component in the smelter ventilation system. 

That information was used to develop a computer flow model of Tomago’s pots and associated ventilation systems, so the team could rapidly test ‘what-if’ scenarios. We could then undertake flow testing under controlled conditions so that we could design flow controlling orificeplates for all 840 of Tomago’s smelter pots,” says Carl.   

This new customisable orificeplate system enabled flexibility in individual smelter pot ventilation flow. Each of Tomago’s potlines are approximately 1.4km long, but each of the pots on the line require the same flow, despite their distance from ventilation fansThat flow could now be controlled by an orifice plate – the closer the pot is to the fan, the more flow restriction the plate needs to provide.” 

Using Advitech’s flow model, it could be seen that the pots additional flow varied between 10-60%, depending on their location and distance from the ventilation system fansEnabling ‘boosted-flow’ during the orifice-plates temporary removal enhanced local pollutant captureand thus assisted in maintaining Tomago’s environmental obligations overall.  

When the time came to install the newly designed system, Carl continued to step the Tomago team through the process.

“Communication is always a really big part of any project. Not only during the proposal and the final report, but in guiding the client through what the changes will look like as they unfold. It’s all well and good presenting what the end product will look like, but it’s important everyone understands how the system will behave between each day of installation – what will happen to process stability? Will we be seeing excessive heat? Will there be a drop in ventilation? They have to trust us.” 

Following the installation of the new orifice-plate system, Tomago Aluminium not only achieved the goals of AP22, but with Advitech’s process engineering expertise they also inherited a potline ventilation system which is more flexible, stable and balanced than the 1983 original installation.  

If you have an unbalanced, uncalibrated system, then some pots get more flow than others – that can lead to local overheating and maintenance issues. You also have less flexibility – now the client can boost flow during maintenance so they have more control over their production line.” 

It was a great project because we helped redesign a major manufacturers way of doing things. And yes, it was a small component in the grand scheme of it all – but it was vital in enabling the client to achieve what they wanted to achieve, which was high production rate and maintenance of their environmental protection obligations,” says Carl.