Fusion of accuracy and control
Enerpac SyncHoist lifting systems are being used to assist in the assembly of the Vacuum Vessel for ITER, the world’s largest fusion experiment, in Southern France. The SyncHoist millimetre lifting accuracy is needed to lift 500t vacuum vessel sectors into an Up-Ending tool for vessel assembly by the ITER Sector Sub-Assembly Tool.
The torus-shaped ITER vacuum vessel will host the fusion reaction. Within this vessel, plasma particles collide and release energy at temperatures up to 150million degC without touching any of its walls due to a process of magnetic confinement. The vacuum vessel comprises nine sectors made of special grade stainless steel. Each sector is 13m high, 6.5m wide and 6.3m deep.
The Enerpac SyncHoist system comprises four, double acting, push-pull cylinders connected to lifting points. As the centre of gravity (CoG) for each vacuum vessel sector may vary from the theoretical, four 225t lifting capacity Enerpac SyncHoists are used to assess the CoG and ensure the lifting of each sector is as close to the plane as possible. Each vacuum vessel sector is delivered to ITER on a rigging platform. A SyncHoist is connected to each of the platform’s four lifting points allowing millimetre control at each point. The SyncHoists are arranged in pairs suspended from header beams connected to the ITER assembly hall’s overhead crane for the 10m lift to the Up-Ending Tool.
Jarl Buskop, assembly engineer, Sector Modules Delivery & Assembly Division at ITER says, “It is essential that we hold the vacuum vessel sector in the plane during lifting. SyncHoist allows us to know the load at each lifting point and control the lift precisely with a 1mm accuracy.
“Another benefit of using SyncHoist to cope with variations in the centre of gravity is the ability to lift the vacuum vessel sector clear of its surrounding transportation frame where there is only 15-30mm clearance for the rigging platform.”
To meet the ITER project requirements, each of the 1000mm stroke SyncHoists hydraulic lifting systems was made completely leakproof. In addition to the vacuum vessel sectors, the SyncHoist lifting system will be used to lift toroidal magnet field coils for insertion in the vacuum vessel.
Enerpac SyncHoist – Precision Control
The Enerpac SyncHoist range includes lifting cylinders with 110 and 225t lifting capacities, plunger strokes of 1 and 1.5m and are capable of high precision lifting accuracy of +/- 1mm over the full stroke. A single operator controls and oversees the entire hoisting job, using a portable wireless control unit for remote control of all cylinders.
In addition to synchronous lifting and lowering, the operator is able to lift and lower each cylinder independently for balancing, tilting and positioning loads. For repetitive hoisting tasks, the controller can also be pre-programmed for positioning, tilting and aligning of loads. The wireless controller allows the operator to work at a safe distance. No cables are needed, so there is no risk of entanglement or tripping hazards.