More power to you20 September 2011
As a boom in big energy projects increases the size of components passing through ports, users must decide between mobile harbour cranes, crawler cranes, and ancillary equipment to suit the lifts. Cristina Brooks considers the options
The market for energy-related harbour cranes is increasing. Enerdata reports energy demand going up by 5% last year. Buying higher capacity port cranes for project cargo makes sense with a view to meeting long term demand to handle larger energy components. Peter Klein, head of marketing for Demag’s port cranes brand, Gottwald Port Technology, remarks, “Turbines, plant components, wind turbine components are going to be steadily heavier.“
Bulkier components required by the power industry include generators, gas and steam turbines, diesel engines and plant components. Wind turbine parts can require complex lifts: Nacelles are heavy while the rotor blades are difficult to maneuver. A prevailing trend in the port environment is to increase the handling capacities on equipment for project cargo, usually either a specialised mobile harbor crane or a regular crawler crane, in order to lift these components.
“If the stevedore is doing lifts case-by-case, a crawler crane may be the right choice. If the stevedore is lifting wind turbine components continuously, a mobile harbour crane would be the right choice,” says Klein.
Unlike some cranes used to handle containers, mobile harbour cranes used for project cargo need to be able to do heavy lifts at a shorter radius. “Heavy lifts often do not need a long radius. The heavy parts to be lifted are shipped on or in relatively small vessels,” says Klein.
The majority of mobile harbour cranes sold are made to handle bulk and containers, but the high capacity end of the mobile harbour crane spectrum is also in demand for project cargo.
Cargo traffic statistics are rising in parts of the world. The National Retail Federation reports a 5% increase in retail container traffic in the US this half. This may be an indication that other kinds of cargo traffic will rise, with project cargo increasing in volume as well as bulk.
Turbines on railway lines
To keep up with demand for turbine lifts, the Port of Vancouver USA has ordered two high-capacity Liebherr harbour cranes.
The location of the port on the Columbia River feeding into the Pacific Ocean means it is heavily utilised by inland wind farms in the US.
The port has ordered two 140t LHM 500 cranes for handling 69t nacelles, 21t hubs and 40m long blades. The first was delivered in 2006 and the second was delivered in 2009.
Having two cranes increases the capacity of the port to enable lifting parts of up to 280t.
Currently, the two cranes work together as an assembly line to load turbine parts into railway cars. “We need two heavy-lift cranes to efficiently move cargo across the port. In other words, we’ll be able to simultaneously unload vessels with one crane while loading cargo to trucks or rail cars,” says executive director of the Port, Larry Paulson.
Ports often handle turbines with two large capacity mobile harbour cranes. Liebherr’s most popular mobile harbor cranes for handling wind turbine parts are the 140t LHM 500 and 144t LHM 550, which shows the heavy capacity required by such projects.
Joachim Dobler, Liebherr’s head of marketing for mobile harbour cranes and reachstackers, says, “Most popular for project cargo are cranes with maximum capacity over 100t (LHM 420, 550, 600).” Liebherr’s highest capacity mobile harbor crane is the 208t LHM 600.
Recognising the need to provide more mobile harbour cranes with capacities in the over 100t category, Liebherr has released two additional models. The LHM 420 is the successor of the LHM 400 and the LHM 550 is the successor of the LHM 500.
The newest crane, the LHM 420, has a maximum capacity of 124t at a radius of 12m while the LHM 550 provides a single heavy lift option for project cargo of up to 144t at a 20m radius.
“The flexibility of the Liebherr mobile harbor crane concept sets no boundaries with regards to shape and size. Limitations are just set with regards to load and outreach,” says Dobler.
He explains that the load capacity generally decreases with the increase of the outreach, or radius, which is why Liebherr has developed the optional Syncratronic feature to double capacities and increase outreach through an automated tandem lift.
Tandem lifting, or lifting with two cranes to improve capacities and outreach, traditionally requires two drivers to synchronize their movements. Risks of this kind of lifting include decreased productivity, owing to the poor visibility and risk of collisions between the boom, the load, and obstacles.
Operators doing traditional tandem lifts must also worry about international standards requiring that their cranes be loaded to only a 25% of their capacity in case of a shift in the centre of gravity.
The Sycratronic feature integrates with Liebherr’s crane management system to synchronise luffing and slewing movements and keep the center of gravity level.
By preventing a shift in the centre of gravity, it allows operators to tandem lift with cranes loaded to their full capacity without breaking compliance with international standards.
Dobler says, “The LHM 600 can lift 208t up to an outreach of 16m. At an outreach of 24m the crane is still able to lift over 150t. Now, with the Sycratronic system, two cranes combined are able to lift 416t up to an outreach of 16m and over 300t up to an outreach of 24m, respectively.”
Tandem lifts with other cranes
Gottwald has sold a Model 7 crane to a Port of Aalborg in Demark and to handle wind turbine parts weighing up to 140t. It is intended for use in single heavy lifts, as well as manual tandem lifts with other cranes.
The Model 7, which has a lifting capacity of 100t and a maximum radius of 51m, is one of Gottwald’s Generation 5 family cranes, the so-called ‘large’ crane family most popular for project cargo. The family is made up of Model 6, Model 7 and Model 8, with lifting capacities of 125t, 150t, and 200t respectively.
Upping capacities through tandem lifting is also attractive for Gottwald clients. Through Demag, Gottwald has recently introduced its Tandem Lift Assistant and its Vertical Lift Assistant, which can be bought as an option or retrofitted to the Visumatic crane management system.
Gottwald officials said that the Tandem Lift Assistant has been developed in response to increasing demands for capacity and maneuverability. “With lifts increasing not only in weight but also in their overall dimensions, it is not only the demand for more powerful cranes that is growing.
There is a growing need for alternative methods of lifting.”
Maneuverability is especially desirable for turbine parts. “In view of the problems often posed by awkward shapes, such as the extremely long tower and rotor blade sections, it has become commonplace to handle these items by tandem lifting with two cranes.”
The Tandem Lift Assistant provides standard compliant capacities on par with other industry leaders.
Klein says, “In case operators need higher capacities they can apply even two cranes in tandem lift. Lifting capacity increases up to 400t when Model 8 cranes are applied.
“Tandem lifts are needed for both heavy lifts and lifts for very long components, for example wind turbine components.”
However mobile harbour cranes aren’t the only option, and some ports have met the demand for handling bigger project cargo by applying the tandem idea to hired crawlers.
Careful crawler and ship crane use
UK-based firm hire firm Weldex has invested not in traditional port equipment but in crawlers. With its expertise in using crawlers for handling project cargo, it offers specialized lifting services for the energy and power generation industry.
Siemens awarded Weldex the contract for port handling and loadout of 175 3.6mW wind turbines to be installed by an installation vessel in the estuary of the Thames. The project, called London Array, will be the world’s largest offshore wind farm.
The firm will begin lifting Siemens turbine parts at the port of Esbjerg in Demark in August, and the first load will go out in a month.
Esbjerg personnel normally handle all shipping and loadout services at the port, however, owing to the complexity of the lift operation statements, the cranes will all be operated by Weldex personnel.
Weldex is using two crawlers, a Liebherr LR1750SL and a Liebherr LR1200, for lifting nacelles, hubs, support frames, tower sections, blades, power units out of storage and moving them onto the quay. The largest of the two crawlers can lift 750t at 7m radius.
After Weldex uses a crawler to remove turbine parts from the storage areas on the quay front, it will load the components directly from the quay onto a barge. Later in the project an installation vessel may load itself directly.
All of the heavier turbine parts, such as the nacelles and hubs, will be placed on the barge by Liebherr crawlers.
“Nacelles, hubs, bottom and middle tower sections all require some pre-loadout assembly work and are delivered by road transport trailers well before loadout. Cranes then lift and move them to the loadout barge,” says Brian Hyde, the technical services manager at Weldex supervising the project.
The lighter blades will be carefully delivered using a reachstacker. “Blades and top towers are delivered ‘just in time’ by either reach stacker or forklift truck. These are only moved a short distance from holding area, less than a kilometer,” says Hyde.
Moving the blades requires not only lift planning but occasionally ancillary equipment like lift frames.
Hyde says that handling blades can be a challenge. “Large sail area means wind is a continual problem. They are also very fragile so great care must be taken when handling. A lot of engineering from Siemens goes into lifting and installing these. Special lift frames, tugger winch systems, special grillages, trailer systems for moving them.”
Sometimes, to control the problem of wind pushing on blades and turbine towers, two pieces of equipment, such as a small crawler and a reachstacker, will be carefully maneuvered in a tandem lifts.
“Towers are delivered horizontal and up-ended using two pieces of plant. A tailing crane can be a small crawler or a reachstacker. Blades are easier to lift and control using a tandem lift,“ says Hyde.
Along with SPMTs, that handle road travel heaviest loads, Hyde says that heavy lift crawler cranes are often used for project cargo.
The crawlers Weldex uses to lift project cargo are the Liebherr LR11350, LR1750, LR1300W, LR1400W, Demag CC2800-1 NT. “The latter three have narrow tracks for walking on wind farm roads,” says Hyde.
Even with crawlers, manufacturers are gearing cranes for heavier lifts, which suits the market for handling increasingly large project cargo for the energy sector.
Hyde says, “Five years ago a 600t crane was largest about, now cranes double this size are common place enquiries. Most of the crane manufacturers have 3000t cranes available.”
Crawlers ‘walk’ oil rig parts
Texas Terminals, a stevedore client, is also using a crawler to lift project cargo for the oil industry. The Port of Houston, with the fifteenth highest volume of traffic globally, handles oil well equipment, power generation equipment, and project cargo for petrochemical plants.
The stevedore is using a 300t Link Belt 348 crawler to load assembled sections of blow out preventers onto ships.
The Link Belt 348 can lift 44t at a 20m radius, but the 87t sections are being lifted at a 12.5m radius. Each blow out preventer section is 6m long.
The Link Belt 348 ‘walks’ the cargo from the truck to the ship. “Smoothness and maneuverability are key requirements for the 300t machine, particularly when a back-up of ships occurs due to foggy weather. It must maneuver around the tight storage isles of oddly shaped heavy industrial,” says Link Belt.
Crawlers in the over 100t range, such as the Link Belt 348, fall within the observed trend for dockside equipment towards large, flexible multi-use equipment designed to handle heavier project cargo. Ports using the models outlined in these case studies are suitably equipped for energy markets.
While using crawlers for heavy project cargo provides a maneuverability that is particularly useful for one-off applications, such as the installation of a large wind-farm or an oil rig, Ports considering using this equipment should be wary of high loading cycle, which some warn will ultimately lead to crane damage.
For this reason ports should stick to the rule that crawlers are useful for ‘case-by-case’ basis, while choosing mobile harbour cranes for handling a project cargo on a regular basis.