Two STS units, part of a multi-crane order, were delivered to the Tanger Med Alliance by Liebherr completely upright
The ship-to-shore container portals sector is experiencing lower demand, but innovations in terms of order pipeline and design continue. John Bensalhia reports.
Many container terminal operators have shown interest in remote-controlled and / or automated STS cranes. However, Juan Jodar, director of Ship-to-Shore (STS), Kalmar, says few global terminal operators definitely do this.
“It is not easy to move from conventionally manned operation on board to automated or remote-controlled operation in an existing terminal. Hence, it is more likely that new greenfield projects will be automated from the start. On the other hand, it is still not clear that remote STS productivity can be higher than conventionally manned. “
Jodar adds that it is expected that the number of automated terminals and, consequently, the number of automated STS cranes requested will increase in the coming years.
According to Svend Videbaek, Marketing Specialist at Konecranes, automation of STS cranes is increasing from operator-assisted design features to remote and semi-automated operation of STS double-carriage cranes. “The customer will have certain preferences with regard to his terminal operation, which will determine the degree of automation. Recent trends indicate that the preference for STS automation is increasing and that a higher degree of automation will be built into STS cranes in the future. “
In December 2020, Camco Technologies announced the delivery of its OCC (Optical Character Reader) technology for five ZPMC STS cranes to be installed in the Beibu Gulf Port Qinzhou, China.
BoxCatcher technology is used to register and identify containers during loading and unloading of ships. The cranes on which it is mounted will be installed in the greenfield at the first automated container berths at the Qinzhou Terminal.
Trevor O’Donoghue, Marketing Manager at Liebherr Container Cranes Ltd, agrees that the demand for automation and remote control will continue for the foreseeable future until 2021 and that the use of remote and virtual tools for operation, maintenance and commissioning will continue to increase.
“Liebherr has been supplying semi-automatic STS cranes for many years. This trend will continue in 2021, as Liebherr supplies advanced STS cranes with both automation and remote control, ”he states.
RIGHT BALANCE
Interestingly, STS crane suppliers have taken slightly different approaches to strike the right balance between crane weight and structural strength. “Our approach is customer orientation, in which we do not endanger the ease of maintenance or the comfort of the crane operator during STS operation. The latter is specifically related to structural strength and rigidity, ”says Videbaek. “With this in mind, we have developed an STS product platform that contains certain parameters that are of the greatest importance: Important structural parameters are crane stiffness and durability against fatigue. This gives the customer smooth, predictable and precise crane behavior and fewer surprises when structural fatigue over time is taken into account. “
“As the cranes have grown in size, Liebherr’s unique design has evolved over the years to achieve the optimum weight-to-rigidity ratio while maximizing the crane size for operation and reducing wheel loads,” explains O’Donoghue. “The use of high-strength steel and a lattice boom and girder in the Liebherr design ensures that the crane has inherent strength and rigidity as well as an optimized weight with a low center of gravity. These design features are ideal for large cranes. “
In recent years, Kalmar has found that most inquiries and tenders for STS cranes are for Malacamax or Triple E STS cranes: cranes that can handle and operate the largest container ships.
“The biggest challenge is that most of these cranes are used at existing berths that are not always ready to take these huge cranes due to the limited maximum permissible wheel loads,” explains Jodar. “The first problem is therefore to keep to the maximum permissible wheel loads at the company berth. This means that despite the larger crane size, manufacturers cannot add the weight of the crane as much as we would like. “
According to Jodar, it is a must for Kalmar to equip a crane with very good structural behavior. This means that it can offer structural strength and rigidity at a good level (> 0.7 Hz in the direction of the car). “Our mono-box design helps us achieve these goals (large cranes, accurate wheel loads, rigidity). We can offer a comfortable, stiff crane design that has virtually no deflection when in operation. “
STROKE AND SPEED
In terms of lifting and operating speeds under load, there is a growing trend towards longer lifting distances and longer travel routes, which requires higher operating speeds, according to Videbaek. “However, these parameters cannot increase indefinitely, as farm operations can limit the productivity of cranes on the quay. There are also limits to the physics of the steel portal structures of STS cranes. In such cases, Konecranes carries out simulations based on the specifics of the container terminal in question. “
O’Donoghue notes that STS cranes have recently seen significant changes in reach and lifting height to keep up with the evolving size of container ships. “Fifteen years ago, the majority of STS cranes were smaller, and large Megamax cranes were only starting to show themselves. Cranes with a reach of more than 70 m and lifting heights of well over 50 m are the order of the day. Increased speeds, especially with hoists and trolleys, can be felt. “
Although the STS cranes got bigger and bigger, the lifting and carriage speeds for Kalmar Super Post-Panamax STS cranes (19-22 rows) and Malacamax / Triple E STS cranes (> 23 rows) remained the same.
“The main reason is that these speeds are already quite high and there is a crane operator on board in the cabin,” explains Jodar. “In practice, the operating speeds are lower because operators want to limit them or define flatter acceleration ramps. So there is actually a gap between the hoist / cart speeds and the operating speeds. “
Jodar adds that this gap can be narrowed if semi or automated STS cranes are considered. “In these cases there is no operator on board, so the automatic part of the cycle can run at maximum acceleration and higher operating speeds.
“Another reason the hoist / cart speeds are not increased is that STS cranes are not typically the bottleneck in container operations at the terminal. Therefore there is no reason to specify and request higher speeds for the STS cranes. “
ENVIRONMENTAL DAMAGE
From the point of view of the fact that they are electrical machines that are fed with electricity, STS cranes are environmentally friendly. The technology helps with more efficient electric motors, drives and control systems that provide more accurate power consumption for an STS crane.
“STS cranes still need grease and oils, but good design can also reduce their use,” says Jodar. “In Kalmar we keep the hydraulics to a minimum. We design so that secondary functions are driven electrically and not hydraulically as much as possible. Oil consumption can also be reduced by implementing a central and automatic lubrication system that provides the required amount of oil at the required points in the crane installation. “
“With digitization, we offer advanced tools to improve the productivity, serviceability and service life of our STS,” says Vidbaek. “The environmental impact can also be reduced by modernizing and retrofitting existing equipment. One of the main environmental impacts of the STS crane is its energy consumption during operation. We are also always looking for more eco-efficient solutions to simplify maintenance, for example by minimizing the need for hydraulic systems and in some cases using special technologies to reduce the noise generated by the crane. “
The Liebherr STS lightweight crane design with lattice structure boom and beam has a reduced wind sail area, which means that the crane then uses less power during operation.
O’Donoghue continues: “Airtight elements are used in the manufacture of the portal structure, which reduces the overall paint requirement. Fully regenerative drives designed by Liebherr with an active front end and liquid cooling enable optimal energy efficiency / regeneration and a much quieter drive. This helps reduce AC power requirements and noise emissions, and delivers industry-leading power consumption per box movement.
“The mechanical Liebherr pendulum protection supplied with all cranes leads to improved efficiency and lower power consumption per cycle, while the standard LED lighting further reduces operating costs.”
FUTURE PROSPECTS
Looking to the future, Jodar states: “As the coronavirus problem will persist, at least in the short term, we expect the market to recover somewhat from the 2020 numbers, but probably not as much as one could hope for . We’ll have to wait a little longer to see whether or not the terminal operators reactivate their investment plans within this year. “
O’Donoghue summarizes, “Our observation was that the pandemic has in some cases created a degree of caution in investment decisions. We continue to deliver cranes efficiently, sign new contracts and work with our customers on the challenges and uncertainties in the market. We are sure that more stability and security will return in 2021, which in turn will lead to more investment decisions. “
