Refining industrial instrumentation

THE QUEENSLAND Alumina Limited (QAL) refinery at Gladstone on Queensland’s central coast is the biggest refinery of its type in the southern hemisphere.

THE QUEENSLAND Alumina Limited (QAL) refinery at Gladstone on Queensland’s central coast is the biggest refinery of its type in the southern hemisphere.

Commissioned in 1967 with an annual production rate of 600,000 tonnes of alumina, today QAL produces some 3.95 million tonnes of smelter-grade alumina per year.

The operating environment is tough on instrumentation, and equipment that will keep performing under normal and extreme conditions is virtually mandatory to maintain target production levels.

A pro-active instrument replacement program is seeing Yokogawa process control instruments installed throughout the plant – and proving more than a match for the aggressive environment of an alumina refinery.

According to Ian Kretschmann, instrument support engineer at QAL, an alumina refinery is tough on process instrumentation.

“But reliable data is at the very heart of our production and to get reliable data we need reliable instruments. That’s why we are progressively replacing the older instruments throughout the plant with Yokogawa products.”

Kretschmann utilises the internationally recognised Kepner-Tregoe Decision Analysis Process (a rigorous testing and analysis assessment system for decisions) to determine the suitability of field instrumentation equipment destined for installation throughout the plant.

“For instruments to be considered ‘plant standards’ they must be the best device as per the Decision Analysis, and have met all the requirements of the testing procedure,” Kretschmann explained.

“All the Yokogawa instruments we use passed our tests and continue to prove their performance and reliability on site.”

The instrumentation installed at QAL includes magnetic flowmeters, pressure and differential transmitters, temperature transmitters and liquid and oxygen analysers.

As part of QAL’s ongoing instrument improvement program at Gladstone, any instrument failures are carefully analysed by site technicians to try to determine the root cause for the failure and if the failure is an issue for manufacturers to address or a result of poor instrument equipment application.

“We are keen to use instrumentation that contributes to our business” Kretschmann said.

“From our point of view, feedback on product performance, or premature failure, to the manufacturer could bring about improvements in that instruments design.

“Improved instrument performance translates into improved production capability for us.”

Kretschmann believes there are ‘horses-for-courses’ in terms of instrumentation for particular industries and says that Yokogawa equipment is ideal for heavy industry, mining and minerals processing; areas where he has many years experience.

He argues there are two primary requirements for process control instrumentation in industrial environments.

The first key requirement in an instrument is accuracy.

“In common with every other large processing plant in the world, our operators, chemical engineers and planners rely on data for plant modelling,” he said.

“They need accuracy to make accurate models. Variations in readings lead to false modelling, which affects future planning and control.”

He said that some instruments have been known to drift in accuracy, which can have long-term implications further along the process.

And in extreme examples, inaccurate readings can ultimately shut down or overload process equipment.

The second requirement is reliability and that heavy industry needs reliability with virtually zero failures. The instruments must keep going, to keep the process going.

“On these two requirements, along with overall instrument quality and support, Yokogawa gives us the performance — and ultimately the operational peace of mind – we look for.”

For more information visit the Yokogawa Australia website at www.yokogawa.com/au/ or email QAL webmaster@qal.com.au.