General Electric : ESP helps Australia breathe easy

It takes more than an Allen key and a caffeine drip to open 50 shipping containers of some 3,000 flatpacked parts and assemble them into a 350-tonne lung that filters air for Australia.

At one of the country's biggest copper mines, the electrostatic precipitator (ESP) that cleans dust particles from the gases emitted during copper processing had reached the end of its useful life. 'After 15 years or so of operation, these systems basically wear out and it becomes smarter to replace the whole thing rather than to keep repairing the old one,' says Jason Price, customer service leader for GE Power in Australia and New Zealand.

GE won the contract to replace a competitor's product with a more energy-efficient and responsive system that would fit within the exact footprint of the old ESP, a 15m x 8m x15m-high structure raised 6-8 metres off the ground on support columns.

'The new GE ESP for this site is equipped with a high-frequency power-supply unit known as a Switched Integrated Rectifier, or SIR,' says Debasish Chakrabarti, director of Air Quality Control Systems for GE Power and Water in the Asia-Pacific region. 'The SIR controller has the world's most technically advanced ESP optimisation algorithm that automatically optimises the system to accommodate changes in the plant process.'

More than 1,700 GE SIR controllers optimise operation of ESPs worldwide, ensuring the lowest possible particulate emissions from industrial processes such as the manufacture of cement, pulp, paper, chemicals, glass and steel; and the operation of coal-fired power plants and ore processing.

At this Australian copper mine, emissions laden with particulates from the smelting furnace are ducted into the first of three electrically charged fields within the ESP. The electrical charge forces dirty dust to collect on vertically hanging metal plates where it builds up to form a thick, cakey surface. Every 10 to 15 minutes a hammer hits each plate causing the gathered dust cake to slide off and into a hopper. The first field of plates removes about 70% of particulate matter; the second, around 15-20%; and the third collects the remainder up to a total of about 96% of particulate removed. The air is then classified by Australia's Environmental Protection Authority as safe for release into the atmosphere.

The ESP is crucial to a mine's license to operate. GE's contract was for design and supply of the ESP and to support subcontractors to assemble and position it. With downtime on mine sites adding up to potentially millions of dollars in lost production per day, replacement of the precipitator was tightly planned by GE.

GE's system designers in India, led by Raja Dey, liaised with the thermal-dynamics team in Switzerland, and co-ordinated with manufacturers in China to make the many components. Putting it all together required the guidance of six technical field advisors led by Wayne Basee, and with Price as project manager. The mammoth team effort will ultimately have taken 18 months from conception to commission, with unavoidable downtime of the ESP contained to less than seven weeks. The new ESP is now in place and on track to take its first working breath at the end of November.

Says Bassee, 'The hardest part is delivering a quality project safely and on time. Safety is first. We've got to make sure we don't injure any person on the job. Our project had 30 to 40 people working around the clock. You've got a lot of work up high, a lot of work on the ground, a lot of hot work, you've got sparks flying, you're in a dusty environment. So to make sure everybody has the right tools in the right place at the right time, so that they can do their job safely, that's a challenge to co-ordinate!'

Construction of the ESP from its shipped-in, flat-packed pieces began in May this year, 200 metres from the site of the old, still operating, plant. A workforce including engineers, scaffolders and riggers, boilermakers and welders, insulators and cladders, and electrical experts safely swarmed the build, which took about six months to complete.

In late October, a not-quite-flat-packed 1,350-tonne crane arrived at the mine on 20 semi-trailers. Once assembled, the pin-jib rig was ready to remove the old, now disconnected ESP system, and hoist in the new.

'The lifts require major safety planning,' cautions Bassee, 'co-ordinating with the customer to ensure that no-one is in the area, that all outcomes have been considered and have a planned contingency, and that we don't get caught in a wind gust at a critical point.' Two flat self-drive trailers moved the new, 350-tonne ESP, which had been built on a low subframe to accommodate their manoeuvrings, into place for the crane to lift and slowly turn it into position on the raised steel rim - a monumental moment!

With the superstructure secured, it no longer mattered which way or how hard the wind blew. And when the mine returns to full operation, with its new ESP in place, it won't matter whether you're upwind or downwind of the processing plant - the breeze will be clear.