Fast as the Wind
Time is money. As trite as this empty phrase appears, if it concerns the construction of wind farms, then it is as current as it has ever been.
For this reason, and of course due to the increasing demand for renewable energy, the Danish crane manufacturer Krøll has developed a new luffing jib crane which takes into account the special requirements of the wind industry.
The new Krøll K1500L has a capacity of 125t up to a radius of 12.5m and can construct wind turbines of the 5MW class to a height of 170m. In the process the crane operates very close to the tower and in a very small turning circle, as is typical for luffing jibs. In this case, Krøll has gone a step further and designed the K1500L in such a way that allows for the positioning of a very steep jib in order to reach the necessary lifting height.
This steep deployment angle of the 70.1m long jib does increase the risk of instability during sudden gusts of wind or down draughts, however. To counteract this, the very steep A gantry uses a spring damping system which stops the jib from falling below the minimum radius.
The complex usage and construction of the crane places the most extreme demands on all crane components. For this reason, Krøll decided to place their trust in special wire cables made by CASAR.
The 825m CASAR Eurolift Ø40mm hoist rope was put to use here, a rotation-resistant rope, which has proved its exceptional qualities over decades. The hoist rope is reeved with four strands. The hoisting winch, with a capacity of 154kW, can lift a load at a rate of 6m/min and up to 22m/min when bearing no load.
The luffing jib rope is a CASAR Turboplast, a compacted eight-strand Warrington-Seale construction with a plastic-covered steel core. What the K1500L is able to achieve has been proven many times over during the course of the last four months.
To begin with, the crane was put through its paces under so-called laboratory conditions on the Krøll test field in Lynge, close to Copenhagen. The crane passed its 100% load test (125t), as well as its overload test at 125% (156.25t) with flying colours. This was followed at the end of last year with the first field test in Poland.
Here, a prominent Danish manufacturer’s wind turbines were successfully installed. One of the greatest strengths of the K1500L is certainly that it is a free-standing crane that does not need to be anchored to the ground. Its sophisticated construction makes it very flexible. The crane is disassembled into relatively large sections at the wind farm building site for transport over relatively short distances, so that it can be ready for use again as quickly as possible.
If further transport on public roads is required, the crane is disassembled into a larger number of smaller and lighter sections, in order to enable easier transportation. In this way, the M33 Monoblock tower system meets the size requirements for road transport.