10 months ago



Driving bulk handling

Driving bulk handling operations at China’s Wugang port with total reliability Capable of handling up to 5,000 t of iron ore per hour, the ship loaders and unloaders at Wugang Port are the largest machines of this kind for civil use in China China’s Wuhan Iron and Steel Group (WISCO), one of the largest steel companies in China, has built a new port to better handle growing volumes of imported ore. Various bulk handling machinery that is installed throughout the port has a total of over 170 geared motors, supplied by German manufacturer Nord Drivesystems that ensure everything stays reliably in motion. MOTION AND DRIVES In the last few years, Zhoushan Archipelago has emerged to popular tourist destination, but its other role as a center of trade is steeped in an old tradition. Zhoushan’s major islands lie about 150 miles south of Shanghai and the Yangtze estuary. Even centuries ago, their proximity to these bustling cities and the Yangtze, one of China’s premier waterways, has made the Zhoushan ports the region’s chief entrepôts for all sorts of goods. In modern times, these have come to include industrial commodities such as steel, mostly destined for Wisco, China’s oldest steel giant. Due to domestic shortage of high quality ore, the company imports most of it, arriving usually through East China Sea in huge oceanic vessels. Inevitably, the cargo must offloaded and transferred onto smaller ships – even on the lower reaches of the Yangtze, as large freighters would be stopped cold at the river bridge in Nanjing. 10,000 dwt ships, on the other hand, can pass under it and make their way onwards to Wuhan. Mammoth sized machinery for a mammoth sized port Demand for Wisco’s products has grown steeply over the course of the last decade and establishing additional loading and unloading bases along the coast became vital. Partnering up with two cofinanciers, Wisco eventually came to hold a stake in the new port construction project in the island town of Wugang, in the south of the Zhoushan Archipelago. All facilities at Wugang Port were built in 2010-11. The German manufacturer of full-scale drive solutions, Nord Drivesystems, has supplied more than 170 heavy duty geared motors. As inspections, test runs and approvals for full-scale operation have concluded in mid-2012, Wugang now serves as Wisco’s main transshipment terminal with a cargo throughput of up to 30 million t of ore per year. The port includes an unloading berth boasting a water depth of 27 m, where huge ships carrying up to 300,000 dwt can arrive. Three loading berths are 15 m deep and can accommodate smaller ships – one will fit a 50,000 dwt class vessel, two are cut out for 10,000 dwt ships. Designed to handle up to 5,000 t of ore per hour, the ship loaders, unloaders, and bucketwheel stackers installed along the berths and yards in Wugang Port are all the biggest equipment of their kind for civil use in China. Delivering what’s expected of them: 100 % reliability Given the port’s location and limited accessibility from the mainland, Wisco’s key requirement for all heavy machinery was extremely high reliability and low maintenance characteristics. It takes at least 1 hour for a maintenance crew coming from the coast or Zhoushan Zhujiajian airport to get to Wugang by ship, plus possible delays in bad weather, which might also rule out helicopters as an alternative. In any case, serious problems with machinery would very likely incur staggering costs for repairs and, of course, disturbances of unloading and loading processes due to dysfunctional equipment. Therefore, highly reliable drive solutions were required to ensure that large gantry cranes, conveyors and similar 30 WORLD OF INDUSTRIES 7/2018

equipment keep moving. Nord Drivesystems was commissioned to supply heavy duty geared motors. Headquartered near Germany’s foremost harbor city of Hamburg, the company has immense experience in the maritime world. Nord has a long track record of supplying mechanical and electronic drive technology for gantry cranes and other port machinery – albeit in other parts of the world. Though Nord now has a considerable presence in China that includes several production and assembly plants and a number of regional offices, the German company only set foot in the country few of years ago. Still, the quality and durability of the drive products as well as the pre- and after-sales services offered by the drive specialist prompted Wisco to equip its bulk handling machinery at Wugang Port with geared motors supplied by the Chinese branches of the German company. A very experienced manufacturer of top-quality large gearboxes, the company ensures long service life, minimum maintenance requirements, and high load tolerance for the complete geared motor. Over 170 units were integrated into cranes and conveyor systems sourced from several different Chinese OEMs. All partners cooperated very well, and Nord’s team was readily available for OEM support throughout the project. From the day Wugang port was opened, all machines have been used to capacity almost all the time, with drives reliably doing their duty. Geared motors for demanding conditions Three very large clamshell unloaders (2,500 t/h) serve the 300,000 dwt berth. These machines incorporate a total of 72 threestage bevel gear units from Nord. Two massive mobile ship loaders (5,000 t/h) are equipped with 16 three-stage bevel geared motors and a two-stage helical bevel gear unit each. These drives are capable of moving large systems along the berth on tracks to position them as needed to access various areas of operation. Another 72 three-stage bevel gear units are installed in three bucket-wheel stacker-reclaimers (500 t/h) for the ore stockyards at the port. All geared motors at Wugang feature a heavy duty housing that makes them suitable for outdoor use and severe weather. Well sealed against moisture ingress and fitted with corrosion- and moistureresistant components, they provide a high degree of protection against the typical challenges of maritime environments. Special paint coats are applied against the salty atmosphere. These units are also tough enough to resist considerable mechanical shock. Most units come equipped with application-specific optional parts, including e.g. dust- and corrosion- protected brakes, micro-switches for continuous brake monitoring, or double canopies serving as drip covers at the motor fans. Such features make these geared motors even more reliable. Designed to move large loads without fail For drives used in port installations, a robust, wear-resistant design also means that geared motors must be constructed to withstand massive forces, since the machines they move are faced with very large loads. All gear units are manufactured from a single housing block – an original Nord development. This design ensures optimal resistance to axial and radial forces as well as high efficiency, high output torques, low-noise operation and minimal maintenance efforts during a long service life. Nord can specify and deliver a versatile range of helical bevel geared motors for port machinery, all from in-house production. Solutions for cranes and trolleys feature a wide choice of gear ratios. The manufacturer supplies two or three-stage designs with a hollow or solid shaft as required. Users can choose between models with a foot mount, flange models, and shaft-mounted models. All types are equipped with the same spacesaving housing, which allows for easy integration. Though motors used in cranes and trolleys often operate around the clock, some loading facilities may also stand still for certain periods of time. The build standard of the drives ensures that normal operation can be resumed directly after even prolonged phases of this kind, without any special maintenance requirements. Moreover, all models are also available as explosion-protected (ATEX) versions if required. Frequency inverters for port machinery Apart from geared motors, Nord’s SK 500E line of frequency inverters provide an efficiency of more than 95 % and a typical overload capacity of 200 % for 5 s. Compatible with all standard bus interfaces, the units are easy to operate and program. Basic models feature an integrated brake chopper with management for brake motor control, which is ideally suited for use in hoist applications. Advanced positioning functions as well as various options including the cost-efficient “Safe Stop” feature according to EN 954-1 and EN 13849-1 are also available. Photographs: Wisco 02 Nord drives move the loaders on tracks along the berth 01 Heavy-duty but low-maintenance Nord geared motors installed for port machinery WORLD OF INDUSTRIES 7/2018 31


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