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The powerful potential of a proper plant process model

Better information = better decisions. A good full plant model improves quality and timeliness of investigations into potential benefits of process improvement scenarios and analysis of performance variations. So why doesn't everyone have one? 

Jock Armstrong Sub-sector Leader

by Jock Armstrong

Global Light Metals Sub-sector Lead, Brisbane

07 December 2017

Disclaimer: What works in alumina works elsewhere (probably!)

Our thoughts in this article relate specifically to our experience in the alumina industry, but the same circumstances exist for any complex industrial processes in a competitive environment.

Alumina refineries are complicated and, as a result, they often have issues

Alumina refinery operators are driven by the need to continuously improve to remain competitive long-term. Though refineries are difficult to optimise due to their complexity.

Making improvements to the asset can also be challenging as unforeseen secondary effects can diminish or even eliminate anticipated project benefits. This presents a significant challenge in making the best decisions to improve.

Complex processes require sophisticated tools

Use of a well-configured mass and energy model of the refinery can assess the true impact and thus value of process changes on the overall plant performance. A good model is your virtual refinery, allowing multiple scenarios and sensitivity analyses to be carried out quickly without disrupting the real refinery. Outputs from the model are the insightful information required to make good business decisions.

What is a plant model anyway?

A plant process model is a mass and energy balance that represents plant process performance. As George Box said, “All models are wrong, but some are useful”. A useful plant model quickly and accurately calculates the mass and energy balances across the entire flowsheet for a given set of conditions. A good plant model will handle potentially critical details such as liquor impurities, precipitation circuit behaviour, predictive chemistry based on chemical equilibria and detailed pressure and heat losses from piping and equipment.

Outputs from the model are the insightful information required to make good business decisions.

What is the advantage of a full plant model?

Better information = better decisions.

A good full plant model improves quality and timeliness of investigations into potential benefits of process improvement scenarios and analysis of performance variations. The ability to rapidly run through any number of scenarios ultimately helps decision making, whether to fine tune the process parameter setting or to decide on the best capital investment.

So why doesn’t everyone have one?

There are several off-the-shelf process modelling platforms such as SysCAD and Aspen. Buying the platform is just the start of the journey. Regardless of platform, significant development and customisation is required to configure and tune a good model to create your virtual refinery. Ongoing updating and tuning is required to ensure the model remains useful.

The skills required for this are specialised. A process engineer with experience in alumina refining and expertise in simulation software is just the thing. Refinery owners frequently struggle to attract, develop and retain the skill base required.

Where do I get one?

Invest the time to recruit and develop suitable people for the work, and ensure you buy a good modelling package. SysCAD is most the commonly used in the alumina industry. Invest in development of the model. Ensure redundancy within the organisation to ensure smooth transitions when staff movements occur. Alternatively, seek assistance from technical service providers, such as Advisian, who can help develop and maintain your virtual refinery on your behalf.

In summary - always use the right tool for the job

We have seen time and again the value of a good plant process model. Whether it helps to tweak that last bit of efficiency out of the refinery, avoid otherwise unforeseen secondary effects or guide you to the best investment decisions, a virtual refinery is an essential tool.

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Jock Armstrong Sub-sector Leader

Jock Armstrong

Global Light Metals Sub-sector Lead

Jock brings over 20 years’ experience in alumina refining to Advisian’s Bauxite and Alumina Centre of Excellence team based in Brisbane. He has in depth knowledge of alumina refinery process optimisation and control, and extensive operations experience acquired mostly at Queensland Alumina Limited (QAL), where he performed several different roles throughout the years, but also at Gardanne and Gove, where he was seconded from QAL to the roles of Redside Process Engineer and Technical Manager, respectively. Jock has delivered significant value to clients through refinery optimisation initiatives.

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