An advanced heavy lifting system has been deployed in Australia to maximise safety and precision during maintenance of a huge dredger at a prime coal mine in the Southern Hemisphere.
The PLC controlled Enerpac Synchronous Lifting system from Enerpac was used by Hydraulic and Pneumatic of Morwell in conjunction with Plant Performance Group to enhance precision and safety while monitoring the 2200-ton load’s centre of gravity during the lift on Dredger 16 at Loy Yang Power.
Dredger 16 is longer than the MCG (200 metres), as high as a 16-storey building (55 metres) and has a slew ring bearing 15.2 metres in diameter containing 177 balls of 200mm diameter each weighing 32kg. It weighs a total of more than 5,000 tons and can remove 60,000 tons of overburden a day.
The successful lifting and balancing of its huge superstructure illustrates the versatility of the Synchronous Lift system for major industrial and civil engineering tasks, including manufactured structures, buildings, bridges, oil platforms, ships, turbines, generators, mills, mining equipment and heavy but delicate computerised/electrical equipment, says Enerpac.
The Synchronous Lifting technology chosen for the task of hoisting Dredger 16’s superstructure to inspect and refurbish the giant machine’s slewing ball race uses digital synchronisation control accurate to within a 1mm between leading and lagging lifting points. Accuracies are available down to 0.1mm.
The delicate job of carrying out the lift with maximum safety and minimum downtime was carried out with the assistance of a team led by Shift Supervisor David Little of Silcar, which is an asset manager and provider of maintenance services for technically complex assets. The task involved two-stage lifting and lowering over 250mm, with the Enerpac Synchronous system governing six 630 ton hydraulic cylinders used in pairs at three lift points.
Project Manager, Tom Lamin, of Plant Performance Engineering acting for Loy Yang Power, said the lift proceeded smoothly, with the hoisting being undertaken on May 7 and lowering on May 13. The huge task was facilitated by the accuracy and fluency of the Synchlift operation, and the real-time centre of gravity display.
Hydraulic and Pneumatic Sales Manager, Robert Lewis, said the job required thorough planning to maximise safety and minimise downtime for a client operating the largest open cut coal mine in the southern hemisphere. Loy Yang operates 24 hours a day mining more than 30 million tonnes a year of the brown coal that provides more than half of the State’s electricity needs.
“Everything is on a large scale – the slewing ring is huge and the superstructure above it is ‘bigger than many ships’, so the job had to be done with incredible care and precision to meet the client’s top world class standards of safety.”
The Synchronous Lifting system used by Hydraulics and Pneumatic was an eight-point model that can be used with multiple cylinders ranging from 10-1000 tonnes capacity each. Larger models feature up to 64 control points. The hydraulic technology involved is the same type chosen to maximise safety on some of the world’s most precise lifts, ranging from Ariane rocket launch pads and oil drilling platforms in Europe’s North Sea, to splitting coal shovels and building and weighing wharves and infrastructure in Australia.
“In addition to being precise and giving us the centre-of-gravity accuracy we needed, the technology had to be able to function flawlessly in a harsh environment, with coal dust blowing around the power unit.
“We needed to be assured – and this turned out to be exactly the case – that the technology package developed in conjunction with Enerpac would operate in total safety and reliability.”
Enerpac Engineer, Ray Paasila said safety was built into the synchronous system –
“During lifting in automatic mode, the software meticulously follows each lifting point and each cylinder. The software also constantly monitors which lifting points are in the highest and lowest positions and whether these are still within the set tolerances. If a correction has to be applied, the 2/2 movement valve opens briefly and the relevant (lowest) cylinder receives a short hydraulic impulse, instantly followed by a new reading. This correction process is so fast that the relays that control the valves give the effect of perfect switches.
“The course of the lifting process can be followed on screen (per lifting point). The software also contains an extra control function, by which the system can temporarily be stopped and manually corrected. Emergency stops also built into the system. If something goes wrong, the system will stop automatically and block all points of support.
“In addition to time saving and the exceptionally accurate and virtually stress-free movement of an object, the advantages of Synchronous Lifting include its ability to record and document the entire repositioning process. All the values are stored in the control systems memory for later use. With satisfactory progression of the procedure, this provides both the contractor and the client with a clear guarantee that excessively high stresses have not occurred.”
Enerpac synchronous lifting technology has been used in Australia for integrated solutions involving high precision civil, mechanical, industrial and maintenance engineering tasks, including the splitting of a dragline at Curragh coal for maintenance and during vital stages of the ongoing expansion of the Dalrymple Bay Coal Terminal near Mackay, where it was used to lift and weigh 80-tonne sections of wharf.
“In addition to time saving and the exceptionally accurate and virtually stress-free movement of an object, the advantages of Synchronous Lifting include its ability to record and document the entire repositioning process.
“All the values are stored in the control systems memory for later use. With satisfactory progression of the procedure, this provides both the contractor and the client with a clear guarantee that excessively high stresses have not occurred.”
Operating through PLC control with touch-screen simplicity, the 700-bar system offers maximum stroke to finely balance complex and sometimes delicate and potentially hazardous structures.