By Dr Mark Cooksey

Optimising plant energy efficiency with better electrical connections

Electrolysis and electrowinning plants require significant electrical energy to produce the maximum amount of product of the highest possible quality.

But energy wastage affects your plant’s stability and energy efficiency, consuming your power and impacting production.

As electricity becomes more expensive, electricity-intensive industries feel the repercussions first — especially aluminium electrolysis, and copper and nickel electrowinning, which use high current electrical connections. It is critical for these industries to identify points of inefficiency in their plants, where energy is being consumed at a higher rate than acceptable.

Our studies show that significant amounts of electrical energy can be lost just in the electrical connections due to poor design and maintenance, such as degradation of the anode assembly in aluminium electrolysis plants.

It is vital to benchmark the performance of these connections against industry best practice and develop a pathway to optimise them to reduce costs, electricity consumption and associated CO₂ emissions.

Ignoring plant energy efficiency can impact your operation

Considerable degradation of electrical connections occurs in electrolysis and electrowinning plants because the process conditions are so harsh.

These connections become increasingly more variable and less efficient at conducting electricity.

Traditionally, most plants have focussed on energy savings related to the electrochemical process, while losses associated with conductors and connections have been largely ignored.

Until recently, there has been little understanding of the modes and rates of degradation of electrical connections and how this directly relates to process variation and excess electricity consumption.

The maintenance of electrical connections is a balancing act.

The choice is either to replace parts as soon as they start to degrade, which minimises energy costs but increases maintenance costs, or allow the connections to degrade, which minimises maintenance costs but increases energy costs and risks sudden failure of the conductor.

Continuing to ignore the problem of plant energy efficiency and taking no action is a huge risk.

Eventually, extreme energy wastage can result in curtailed production or even plant closure due to non-competitive electricity prices and production costs.

In the short term, ignoring this problem can result in excess spending on energy without an increase in production.

There is also an impact on plant managers, who are measured on the amount of metal produced and the cost per tonne of production.

What are the next steps in optimising plant energy efficiency?

Your priority needs to be optimising the maintenance process to minimise voltage loss and keep costs to an economical level.

There also needs to be a change in attitude – switching attention to the ’whole-of-plant’ approach that includes maintenance of the asset.

It is possible to optimise the service life of the electrical connections and the electrode fleet to achieve the minimum total cost to the business, with low capital expenditure.

We have developed advanced computer modelling expertise to investigate the thermal-mechanical-electrical interactions of high current electrical connections.

Combining this deep technical understanding with extensive industrial experience we are able to greatly improve the efficiency of your connections.

For example, we recently met with a client suffering from electrical inefficiencies and energy wastage. They required a re-design of their electrical connections and contracted us for the modifications.

Through this engagement we were able to verify significant energy savings of more than 8 MW using a combination of in-plant measurements, off-line testing and computational modelling (more information about this case study will be presented at the TMS Annual Meeting in Phoenix in March 2018).

The Sustainable Metals team at CSIRO, through our advanced scientific capabilities and our extensive industry experience, is uniquely positioned to add value to your operation. Through ongoing analytical support, training, or solution development, we can help you optimise your electrical connections in electrolysis and electrowinning processes.

Contact the Sustainable Metals team on +61 3 9545 8865 or email me at Mark.Cooksey@csiro.au to leverage our expertise and experience.

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