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Automation solutions key to alumina refinery expansions

21st February 2013


As the major aluminium manufacturers expand existing capacity and build new plants, Sean Ottewell reports on how state-of-the-art automation solutions are being demanded

Rio Tinto Alcan's Yarwun alumina refinery in Queensland, Australia, is currently undergoing an expansion that will increase smelter-grade alumina production at the plant from 1.4-3.4 million t/y by 2011 (Fig.1).

Bechtel Australia, the EPCM contractor for the Yarwun expansion, has selected Honeywell Process Solutions to help design, configure, implement and optimise the major expansion of the plant's existing distributed control system (DCS) and integrate it with the UniSim operator training simulator, the Uniformance product suite and Business FLEX software.

The integrated solution will help increase plant safety and efficiency by providing operators insight into all key subsystems for better decision making.

Potential failure modes

Operators, for example, will be trained in potential failure modes for the refinery so that they are able to immediately bring the process to a safe state if required by plant conditions, safety or security requirements.

The current UniSim models that were successfully used to train plant operators for the first stage of the refinery will be extended for new processing equipment to enable Rio Tinto Alcan to train plant operators on processes offline before the expansion of the facility is commissioned.

The training simulation models that will be extended include the bauxite, clarification, calcination, steam production, and precipitation processes employed at the refinery.

Honeywell will also integrate the refinery's closed-circuit television (CCTV) security surveillance system with access control technology.

Security functions

Rio Tinto Alcan will use Honeywell Enterprise Buildings Integrator (EBI) to manage all security functions from a single platform. Other Honeywell services in the agreement include designing and implementing a Process Information and Management System (PIMS) that will be tied to Business FLEX.

Rio Tinto Alcan commissioned the first stage of the Yarwun refinery in late 2004 after Bechtel and Honeywell implemented the initial process control system. The company announced the second stage expansion plan in July 2007.

"Expanding a working refinery's production requires technology to work together to keep employees safe and operations on track," said Tony Cosgrove, managing director, Honeywell Process Solutions Pacific. "Streamlined information, thorough operator training and effective security play major roles in addressing the challenge.

"Our integrated solution will help keep the plant operating safely and provide workers with information that can improve the refinery's business performance."

Alumina processing

For Honeywell, this is the latest success for its growing alumina-based control business. The company is becoming a leader in the industry now because of its extensive knowledge of alumina processing and its fit-for-purpose technologies covering all aspects of alumina refining automation and control. Today's customers demand reduced costs and improved productivity.

Honeywell says it achieves this in a number of ways, including: equipment control, monitoring and asset management; advanced process control (APC); simulation; both dynamic and steady state, for design, testing, and operator training; production tracking and operations management for the mining, transportation and refinery processes; and full integration to enterprise resource planning (ERP) systems.

Advanced digester unit

From a Greenfield plant to a 'hot' cutover; from heat exchanger re-instrumentation to advanced digester unit control, Honeywell has helped all the major alumina companies improve their processes.

Honeywell promotes a 'safety first' culture both within the organisation and with its customers. So much so that utilising its control and safety systems, six global alumina refineries reported zero lost time injuries from over 600000 man hours.

Benefits

Among the benefits Honeywell claims for its refinery control solutions are:

- Two per cent increase in milling throughput.

- Five per cent saving in power use during milling.

- One per cent yield improvement in digestion.

- One per cent energy saving in calcinations.

- One per cent improvement in caustic loss during mud washing.

- Two per cent improvement in liquor stock control through improved circuit throughput.

For a typical refinery, says the company, this can provide a profit improvement of over US$5 per tonne.

As Asia-Pacific Engineer went to press, the Yarwun refinery was coming out of a period of temporary idling due to a severe blockage in the nine kilometre pipeline to its residue management area. Cleaning of the waste pipeline began after the blockage was discovered on 29th July.

The refinery, which normally operates at a capacity of around 4000t/d alumina, had been idling since that time. Cleaning took place during August.

Risk assessments

Rio Tinto Alcan chief operating officer, Pacific Bauxite and Alumina, Alistair Field said the unusual nature of the task had required extensive risk assessments to ensure all work is carried out within strict safety and environmental requirements.

Despite the blockage, Rio Tinto Alcan was able to meet all of its alumina sales commitments from its other refineries and contracted purchases as well as from existing stock levels of alumina.

The company also took the opportunity to carry out opportunistic maintenance work on the refinery.

Greenfield expansion

Meanwhile, Zurich-based ABB has won orders worth US$113 million from Vedanta Aluminum Limited to provide automation and power products, systems and solutions for a greenfield expansion of an aluminum smelter plant in Jharsuguda, in the eastern state of Orissa, India.

ABB will design, supply, build and 24 sets of high-power diode rectifier systems for four aluminum pot lines.

"ABB automation and electrical systems will become the manufacturing backbone of this smelter plant," said Tom Sjoekvist, head of ABB's automation products division.

He continued: "The combination of standard ABB products and systems and our primary metal and minerals expertise creates an unbeatable offering for customers in terms of productivity, reliability and energy efficiency."

The expansion will double the smelter's production capacity of aluminum ingots, rods and rolled products.

ABB's scope of supply also includes a new 400/220-kilovolt (kV) switchyard to supply the new smelter plant with reliable power, as well as a high-performance process control system with fiber optic current sensors, as well as an ABB MicroSCADA control system for the power distribution network, substation switching bays, power and station transformers.

ABB has already supplied rectifier systems for phase one of the Jharsuguda plant expansion in 2007-08. When phase two is complete in 2009, Vedanta's total aluminum smelting capacity will be approximately 1700000t/y, making it one of the largest integrated aluminum producers in the world.







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