Power for power

25 April 2008

In February 2000 Eletronorte, owner of the Tucuruí Hydroelectric Power Plant, made the final decision on the extension of the second phase of the dam project. Eletronorte contracted ALSTOM, leader of Consórcio Empresarial de Tucuruí (CETUC) consortium, which was responsible for supplying 11 generators, 11 turbines and all the hydromechanical parts, including flood gates, forced conduits, protection systems, command and control and bus way, in addition to assembly and commissioning services.

ALSTOM was also responsible for supplying 75% of the turbines, 72% of the generators and associated equipment, the command, control and protection systems, bus ways and cofferdam floodgates on the suction pipe. Oderbrecht and Inepar were responsible for assembly and General Electric supplied the remaining turbines and three generators.

The extension project includes eleven 375 MW generators (numbers 13 to 23) in addition to the 12 existing units that have been operating since 1992. Phase II of the Tucuruí expansion will be capable of generating 4,125 MW, doubling the current installed power output in this plant to 8,370 MW.

The last turbine wheel for Tucuruí Phase II - number 23 - was moved to site late last year. Brazilian heavy transport and lifting specialist, IRGA Lupercio Torres S.A., from Sao Paulo, took on the challenge.

Over the years experience has taught IRGA that both the physical dimensions and the weight of the load, combined with the natural restrictions on a route through densely populated areas of Brazil with its well developed road infrastructure, required a reduction in the height and overall weight of the load. A girder type trailer is practically the only viable solution under those circumstances, although the tare weight of the girder assembly is relatively high.

Nowadays, a high capacity girder trailer consists of a set of two longitudinal beams, supported by a turning mechanism at either end that is mounted on a set of two hydraulic modular trailers. The open space in between the parallel girders allows for heavy and large items to be loaded in between, either hanging from, or resting on, the girders. The often modular design of the girders, in combination with the hydraulic lifting and stability compensation on the turning mechanism, allows for minimum ground clearance when required.

In addition, the modular design also allows for additional length to be added to the girders to either adapt to the load or create a longer load spread where required by road and bridge limitations. Furthermore, modular beams also allow adaptors to be added either side of the split-up beam to fit directly to the load or to allow the addition of, for example, a lowbed in between.

In this case IRGA decided to use its 400 tonne capacity Randon Nicolas configuration of two sets of 16 axle line hydraulic modular trailers in combination with a splitable set of beams. Adaptors, together with additional upper and lower beams “crating” the turbine wheel, allowed the wheel to be carried in between. It also allowed the ground clearance to be altered, either by lowering or lifting the hydraulic system of the girders. This was in addition to the hydraulic lift capabilities of the trailers. In this way both low underpasses and, to some extent, high obstacles could be cleared.

Extensive preparations

A team from IRGA's engineering department was tasked with the preparation of the project. Four months prior to the start of the transport a final and detailed road survey was carried out to confirm the routing as per previous investigations. The starting point was ALSTOM's factory in Taubaté, Sao Paulo. The first part of the move, a distance of about 300 km by road, would end in the Port of Santos, Sao Paulo.

This route would also include passing through Sao Paulo, the largest city in South America. This 45 km stretch through the city had its own complications. First the engineers and technicians had to focus on the geometry of the loaded transport configuration, measuring up to 110 m long, 8.70 m wide and 5.80 m high. Height adjustment by the trailers allowed for an additional +300 mm and -200 mm, while the hydraulic girder system offered an additional lift height of 1,200 mm. The survey learnt, for example, that the shoulder of the highways had to be used, which meant preparation, to enable the vehicles to pass bridges with too low a clearance of 5.50 m.

Following discussion with the authorities and their preliminary approval of the route, the team focused on the structural strength of the bridges and viaducts to be passed. In this respect the fully loaded 32 lines of trailers would weigh in at about 472 tonnes, giving an axle load over 8 wheels per line of about 14.75 tonnes.

Depending on the inclination, two to four heavy duty tractors, weighing about 45 tonnes each, would increase the combined gross weight. Based on their documented findings and calculations the route was also found and approved to be structurally sound and capable of supporting the loaded trailers and tractors, although additional preparations had to be carried out in a number of locations.

Preparations also included the next steps in the transport process. In the Port of Santos the turbine wheel had to be transferred to a different trailer set up for transfer on to a seagoing barge. On arrival in Belém the turbine had to be transferred again, this time on to a river barge for final shipment, unloading and installation in the Tucuruí hydroelectric power plant.

Monster move

Once the preparations and permits from all municipal, state and federal authorities were approved and available, the transport was scheduled to leave from ALSTOM in Taubaté on 21 October. Prior to that the turbine wheel was loaded in to the girder frame using an overhead crane.

The approximately 300 km journey to Port of Santos, the first point of transfer, took some 30 days. Where possible highways were used. To pass under viaducts that were too low over the highway, the guardrails had to be removed so that the road shoulder could be used. Close attention had to be paid in the planning to the low speed of the convoy and the overnight parking locations considering other traffic on the route. To minimise disturbance to the flow of traffic, stopping points were pre-arranged.

Due to the excessive gross weight of the convoy bridges were a major point of interest to the authorities despite the fact that permits had already been issued. Independent engineers monitored the bridge crossings. In addition, the almost standard procedures had to be followed for removing and replacing street furniture and overhead wires. Four different highway authorities of the Brazilian state highway system were actively involved during the transport.

The already exceptional transport was made even more so by the necessity to cross the city of Sao Paulo. With some 15 million inhabitants it is by far the largest city in South America. The transport had to use city roads to find its way through. This, of course, added a number of additional complications, mainly because of the enormous physical dimensions of the girder trailer set up and its load. Trees had to be trimmed and lampposts, traffic signals, etc. had to be temporarily removed or even removed to another location.

Electricity and telephone wires hanging from poles crossed the roads at too low a height for the convoy to pass underneath so both had to be disconnected to let the convoy through. It was also decided that it would be better to drive in the opposite direction to the flow of traffic, which regulated the late night traffic better to keep traffic jams to a minimum. It was decided that to keep disturbance both to traffic and inhabitants to a minimum the convoy would travel only during the night. As a consequence, the 45 km route through Sao Paulo required five nights and the location of additional suitable intermediate parking locations.

An insurmountable problem was an elevated concrete by pass on the route through Sao Paulo. It had a clearance of only 5.00 m. This had already been established during the preparation phase and discussed with the authorities. IRGA proposed to use its 400 tonne capacity hydraulic gantry system to lift the complete concrete by pass to allow the convoy to pass. Engineering calculations showed the feasibility of this solution. It was accepted and worked without problems.

Mode transfer

After travelling for about a month the turbine arrived safe and well in the Port of Santos on 21 November. There the turbine had to be transferred on to a different trailer set up to be driven on board a barge for the sea journey to Belém, a distance of about 2,520 nautical miles. For the remaining part of the journey IRGA used a 12 axle line hydraulic modular trailer, in one-and-a-half 12 wheels per line mode. The trailer was driven on board while the barge was ballasted during the roll-on procedure. After a 20 day journey by sea the barge arrived in the port of Belém on 26 December.

Belém was the starting point of the final part of the journey by river. The turbine was discharged in roll-off and directly transferred in roll-on on to a river type barge. It took about 48 hours to sail the 220 nautical miles of the Tucuruí river to arrive at the jobsite on 31 December. And still the operation was not finished.

As there was no possibility to discharge the turbine wheel by roll-off it had to be lifted off and temporarily stored on the quay. In that way also the tractor and the trailer were lifted off using a 350 tonne capacity gantry crane owned by IRGA. Once on land the wheel was reloaded and the final 4 km was covered on site and within reach of the hydraulic lift tower system of the power plant for final installation.

After about 70 days, including some idle days as a result of bad weather, the project was successfully accomplished according to plan by IRGA's team of heavy transport experts. •

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