ABB's Rectiformers Achieve 18% Increase in Energy Efficiency at Sohar and Qatalum Aluminum Smelters

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Researched by Industrial Info Resources (Sugar Land, Texas)--ABB Limited (NYSE:ABB) (Zurich, Switzerland) has augmented the energy efficiency of two aluminum smelters in the Middle East--Sohar in Oman, and Qatalum in Qatar--by 18% through the use of high-power convertors, also known as rectifier transformers or rectiformers, which were installed at the facilities as part of the power and automation solutions packages provided by the firm. The rectiformers supplied by ABB are reportedly the largest and the most powerful ever built.

Rectiformers are used to control and covert alternating current (AC) supplied by the power grid or captive power plants into direct current (DC), which is then used to drive the process of electrolysis and produce molten aluminum. These power conversion stations play an integral role in the aluminum production process. In the event of a failure in power conversion, the pot lines are automatically shut down, causing molten aluminum in the pots to solidify. This disruption can cost a firm $100 million or more.

Each of the Sohar and Qatalum smelters is equipped with five rectiformers, weighing 400 tons each. Each rectiformer at Sohar has a voltage limit of 1,650 volts DC, while each at Qatalum has a voltage limit of 2,000 volts DC but operates at 1,750 volts. ABB previously manufactured rectiformers with a voltage limit of 1,200 volts DC. Because of the increase in voltage limit, the number of rectiformers required at the two smelters decreased from six to five, resulting in cost savings.

The Sohar aluminum smelter contains the world's longest pot line, consisting of 360 pots, and has a production capacity of 360,000 tons per year of aluminum. The facility commenced operations in June 2008. ABB secured the contract to supply a high-power AC/DC convertor station for Sohar Aluminium Company LLC (Sohar, Oman) in January 2006, and announced successful completion of the contract in January 2009. ABB supplied five rectiformers, each with a voltage limit of 1,650 volts DC and current capacity of 103 kiloamperes. Each of these rectiformers weighs more than 300 tons. ABB also supplied five high-speed control and protection systems of the AC 800 PEC series for the rectifier transformer station, a supervisory control and data acquisition system, and a 220-kilovolt gas-insulated substation. The Sohar aluminum smelter is also the first facility in the world to use the Alcan/Pechiney AP 36 technology that enables a DC of 360 kiloamperes to be fed to the pot lines. ABB also supplied its proprietary fiber optic current sensor technology for measurement of current.

The Qatalum aluminum smelter is scheduled to begin operations later this year. The facility will be the world's largest aluminum smelter, with two pot rooms housing a total of 704 pots and a production capacity of 585,000 tons per year of aluminum. The smelter is the first in the world to operate on a rectiformer voltage limit of 1,750 volts DC. ABB supplied the rectiformer substation to pot lines 1 and 2 of the smelting facility under an engineering, procurement and construction contract awarded in June 2007. The rectiformer frame is designed with a voltage limit of 2,000 volts DC, while the semiconductors and fuses operate at a maximum voltage limit of 1,750 volts DC.

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