Ever-larger grabs meet demands of bulk boom
Container ship growth has cascaded into dry bulk handling as operators demand larger mobile harbour cranes to provide handling for both cargoes. John Bensalhia reports.
The progression of the crane is a case of cause and effect: as ship get bigger, so too must the machinery that handles the cargo onboard – or else costly bottlenecks will surely result. Ports must ensure that their cranes constantly keep up with the times. While a port's original choice of crane might have been able to handle older, smaller vessels, it may not be able to work a modern, larger ship.
For bulk ports, the trusty grab must also keep up with the fast-paced size evolution. Here too boundaries are being pushed as grab curves are optimised to get the most amount of cargo in as possible per lift.
Philipp Helberg, marketing manager, maritime cranes at Liebherr, explains the rationale for grab growth: “The number of large bulker sizes has increased. Also, customers get used to the concept of harbour mobile cranes and expect the same or a similar performance for dedicated devices, like an unloader.” As harbour mobile cranes have grown larger due to the increased size of container ships, “bulk capabilities have grown automatically with them”, he says
The increase in size of the crane grab curve means more room for commodities, and as a result, faster handling and greater efficiency in port operations. Mr Helberg explains that grab curves offer a number of benefits in terms of turnover, strength and durability. “A dedicated grab curve which is perfectly suited to the respective application brings advantages in turnover and life time as the crane will only be loaded as it should.”
A notable example of the strength and value of the modern crane grab curve is the Liebherr LHM 420, which has been optimised for post-panamaxes. With a maximum load capacity of 124 tonnes, the LHM 420 can tackle up to 38 containers an hour, making it an ideal choice for bulk cargo handling as well.
The LHM 420 offers a key benefit in that it boasts an impressive grab curve of 75 tonnes. This means that bigger grabs can be installed, which in turn, means higher lifting capabilities, greater turnover per cycle, and also lower fuel consumption.
Shannon Foynes Port Company recently acquired the LHM 420 mobile harbour crane for the handling of bulk products. Shannon Foynes' engineering and port services manager, John Carlton, explains that the Liebherr LHM 420 is the largest crane in the port and its added lifting capacity doubled the port's then-current capacity of 124 tonnes per single lift. The 75-tonne grab curve is an increase from the port's previous crane grab curve capability of 45%. “Everything about this crane is bigger, better, faster, stronger: it's a very significant piece of equipment for the port,” he says.
Pat Keating, chief executive at the port, adds that the Liebherr LHM 420 was a means of “future proofing” the port. “It's something we need for the here-and-now but it's also planning ahead. The greater lift capacity and reach it provides us with enables us to bring in new business. That means more ships, bigger ships and processing them with faster turnaround times.”
Konecranes' mobile harbour cranes also include high performance grab curves, with its range including four-rope grab cranes for continuous-duty bulk handling. Over the first half of 2018, the company has received a number of orders for cranes of different types including mobile harbour and floating cranes to handle a range of dry bulk materials.
One example is the Model 6 mobile harbour crane for European Bulk Services (EBS), providing a maximum lifting capacity of 100 tonnes, an outreach of up to 51 metres, and a 50-tonne grab curve. Jan de Wit, managing director at EBS, explained that the company has expanded and modernised its storage infrastructure for dry bulk products in the Port of Rotterdam. “To benefit in the most flexible way from our new sheds with their removable sliding roofs... this versatile crane will directly load products from the different compartments of our new sheds onto sea-going vessels and vice versa.”
Konecranes' mobile harbour crane technology is not only applied at the quayside but also in open sea operation. In the first quarter of 2018 two Model 8 floating cranes for operations on open seas were purchased by Winning Logistics Company Ltd for handling bauxite off the coast of Guinea, Africa. The cranes offer a maximum outreach of 43 metres and a high-performance 63-tonne grab curve. They are designed in accordance with Lloyd's Register Code for Lifting Appliances in a Marine Environment, which allows Winning to operate the cranes at wind speeds of up to 24 metres/second and at maximum wave heights of 2.5 metres.
Rules and regulations
The style of the grab curve is an important element for ports to consider. Grab manufacturers have come up with design innovations that allow the customer hassle-free, efficient cargo handling.
A notable consideration for ports can be a country's rules and regulations for equipment. In Japan, a crane's lifting capacity curve must be designed to meet Japanese safety standards.
Terex Port Solutions’ Model 2 crane was supplied last year to the south Japanese Port of Otake. The Terex harbour crane's lifting capacity curve was adapted to the country's requirements, with a maximum lifting capacity of 62 tonnes, an outreach of up to 40 metres and a maximum lifting speed of 85 metres per minute.
Makoto Aso, president of Chikuho Seisakusho (which ordered the crane), commented: “Otake is a major port for the steel and chemical industry located in the region. Thanks to steadily increasing production, the handling volumes have risen consistently over the past few years. The favourable geographical location has also contributed to this.”
Kinshofer's Re-handling Clamshell Bucket is designed for the loading and unloading of bulk materials in large quantities. It has a flat, closing curve, which, with its widely spaced pivots, results in maximum capacity - meaning faster, efficient operations for ports. Furthermore, the design of the bucket means that the ground surface has guaranteed protection: for example, during the process of discharging from a ship.
The lower risk factor of a grab design also applies to the Nemag Scissors Grab. Along with the key benefits of lifting up to 120 tonnes in weight, the grab design and horizontal digging curve reduce the risk of damage to the ship.
Designers of grabs are also introducing unique designs of grabs to ensure a smooth bulk cargo handling process. A case in point is the Electro-Hydraulic Orange Peel Grab from Shanghai Guanbo Machinery Equipment Co. Ltd. Not only is the structure of the grab simple to use and operate, it's also made to function in various harsh environments. Designed for tough materials such as stones and scrap, the Electro-Hydraulic Orange Peel Grab benefits from a unique sacral design curve that makes it ideal for loading and unloading many kinds of bulk cargo. In addition, the Shanghai Guanbo Wireless Remote Control Grab features an effective grab jaw curve, making it another good candidate for handling bulk cargo at ports.
With crane manufacturers continuing to provide innovations that make port operations as easy, flexible and efficient as possible, the grab curve looks set to grow even more, both in size and importance.
GET A PERFECT GRIP
Judging the load has always been a potential issue for crane grab handling and safety. Yet, getting the right load for the crane grab is essential to ensure both strong performance and to make the most of the crane.
To optimise grab fill rates, Liebherr offers SmartGrip technology to boost material handling performance and, importantly, to prevent the risk of overloading the crane.
It operates on every load cycle, automatically filling to the maximum capability, taking the size and outreach of the grab into account.
SmartGrip's self-learning system boosts the material handling performance – after five learning cycles, it can learn how to optimise the grab's capacity utilisation, and can make sure that the grab-filling rate is above the average of 70%.
SmartGrip can also eliminate the time-wasting problem of overload. If there is too much pull on the grab, then the crane automatically switches off. To overcome this issue, SmartGrip controls the fill of the grab to match the crane's load curve. This results in no overload, perfect utilisation of the crane and also an extended crane lifespan, meaning that the port can save money, fuel and time in the process.
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