Archive for the ‘Arklow Wind Farm’ Tag
So to finish off, once all 3 bearings have been replaced, the hub is lifted back onto the back deck, the blades are all reattached in reverse order, like this.
After all blades are attached the nose cone is put on, the HLB attached and the temporarily steps removed, the main lift commences.
Check out the shadow, I like this shot.
Blades attached and the guys have earned a rest, but not a long one, as soon as we jack down and the tides are right we will be moving onto the next turbine.
I would like to thank Fugro Seacore for the hospitality they showed me onboard the Excalibur, a great bunch of hard working guys/Girls and best of all, the food was fantastic.
The Arklow Bank Wind Park is the first offshore wind farm in Ireland and the world’s first commercial application of offshore wind turbines over 3 megawatts in size. It is located on the Arklow Bank, a shallow water sandbank in the Irish Sea, around 10 kilometers off the coast of Arklow with an area of 27 by 2.5 kilometres.
The project is being co-developed by Airtricity and GE Energy. In 2002, Airtricity obtained an offshore lease for a 520 MW offshore wind farm. The first phase of the project, commissioned in June 2004, consists of seven GE 3.6-megawatt generators. They were installed by the Danish offshore wind farms services provider A2SEA. Power cables were laid by Five Oceans Services. All of the turbines have a height of 73.5 metres (241 ft) and height to top of blade of 124 metres (407 ft). The blade length is 50.5 metres (166 ft) and each turbine has three blades. Each turbine weights 290 tonnes.
Right, with the hub and blades removed and secure on the aft deck, we now need to remove the blades, this is a tense time for Tom the engineer, if these barges are out of position by 50cm the blades may not fit into there purpose built holders on the main deck, and we cannot move the barges now.
First the nose cone has to be removed and stored on deck.
Once removed the guys get inside and undo all the bolts from the first blade to be disconnected and the two cranes are attached.
This again is a very tricky lift, both cranes and a banksman are in total communication with each other throughout the whole lift.
The cranes weave the blade through and over the legs. This shot gives you a good view of the Deep Diver and a sense of scale of the operation.
From a different angle under the watchful eye of Tom, seen on the top level.
Here you can see the purpose built racks which hold the blades in place while work is carried out on the hub replacing the bearings. Also the nose cone and to the right the stand that holds the hub in place. To give you an idea of size, the barge is 32m wide and the blades are 50.5m long, so they stick out over the edge a bit.
Once all three blades are removed the hub is made ready for its lift.
And it’s lifted over my office, when I say office I mean the place I have my positioning equipment set up.
Secure on the main deck the guys get to work, these guys work so well together, every one know exactly what they are to do and just gets on with it, what i found amazing was the way they all adapt to the work place, for instance, one guys will be welding one minute, the next he will be working the mini crane to help someone else and later he will be sweeping up when that part of the job is complete, its clockwork at it best.
Old bearing being removed.
Now we are at the correct height we can start the lift, Once the GE guys are in place inside the turbine, we connect the heavy lift bracket to the crane hook and it’s lifted to the top of the turbine.
You can just make out the GE guys connecting the HLB, once thats connected they will undo all the bolts holding the blades in place from the inside.
Around the same time a lifting strop is connected to the number 6 blade (think of a clock face) for the other crane.
All nuts removed the blades and hub are slowly removed.
Now a great bit of crane ballet is performed and you can see why the barges have to be positioned so exact.
Blades are manoeuvred between the legs and pedestal with great skill.
The blades are slowly lowered onto a fixed base on a movable deck at the rear of the barge.
This base is used to secure the hub for the removal of each blade.
Success, Mark the project manager is a happy man. 1st stage complete.
Ok, if you are reading this then I have to presume you are not bored of wind turbines yet, thats good because today is the start of the geeky stuff.
Yesterday I mentioned the height of the cranes and the fact that they can’t reach the turbine in their current position, so what do we do? It’s a jack-up barge so we jack-up, and this is how.
Below is a photo of one leg, the Excalibur has 8 and the Deep Diver has 4, this is on the Excalibur, you see the rusty bit of tube in the middle? Thats the leg, inside the two grey cylindrical bits connected by a 3m hydraulic tube are eight rubber bladders, these rubber bladders are filled with compressed air to expand them and the air released to deflate them, easy.
So to go up the eight bottom bladders expand holding us in place, the hydraulics tubes extend (like in the photo) and once at the correct height the top bladders are filled with air, once we know they are secure, the bottom bladders are released and the hydraulics close to raise the barge by closing the gap, thats 3300 tons of barge, thats about 25.3 blue whales.
In the photo below we are at the top of the leg, about 30m out of the water.
This is what the two barges look like at working height, this was the first time I saw them like this, the rest of the time I was on board the Excalibur.
All of the turbines have a height of 73.5 metres (241 ft) and height to top of blade of 124 metres (407 ft). The blade length is 50.5 metres (166 ft) and each turbine has three blades. Each turbine weights 290 tonnes.
Have a great weekend.