Space is often the primary consideration when undertaking construction work at power plants. Modular construction techniques, along with the precise coordination and delivery of components to site, are the most effective methods to ensure power plant projects proceed smoothly. Mammoet was approached to assist EnBW in constructing a new power plant in Altbach/Deizisau, Germany. The new combined cycle gas turbine fuel-switch power plant will serve as a green energy facility, capable of operating on natural gas, hydrogen, or blends of the two, instead of coal.
Constructing a new power plant adjacent to an existing one posed a significant challenge, with maximising space and minimising disruption being the foremost priorities. To address these challenges, a just-in-time approach was implemented, which significantly alleviated congestion at the site during the construction process. Additionally, the construction of a temporary jetty enabled the main crawler crane to operate continuously, facilitating the offloading of the components and their subsequent installation.
Getting the heavy items to site, just in time
The initial challenge was determining how to transport the heavy items to the construction site and where to store them. Although a storage area was available on site, it was insufficient to accommodate the needs of this project. Faced with a large list of components to deliver and insufficient space to store them, Mammoet temporarily stored the largest items at its storage yard in Schiedam, the Netherlands. Transported to Schiedam by sea, the components were subsequently marshalled, stored, scheduled for delivery, and shipped to Altbach just-in-time on specialised river-going vessels. The river Neckar runs alongside the power plant, which has an existing jetty. However, utilising this jetty as a trans-shipment point was not feasible as it would have significantly interfered with the activities at the site.
Many complex components, very little space
Numerous components required storage and subsequent shipment to the site, including HRSG modules, a generator, a gas turbine, a transformer and stack modules. The 15 HRSG modules, weighing between 80 and 250 tons, presented a particular challenge due to their 30 metre length, which rendered them exceptionally fragile.
“It is a flexible module that does not tolerate deformation and therefore had to be kept perfectly straight at all times,” explains Leonid Sinelnikov, project manager at Mammoet. “We meticulously examined every stage of their handling to ensure they remained undamaged. This included ground preparation at Schiedam and the use of specialised lifting beams and rigging tools for their transportation and offloading.”
Two crawler cranes, a main 1350 ton crane and a 600 ton tailing crane, were utilised to tail up the HRSG modules from a horizontal to a vertical position. Additionally, the modules had to be lifted over the top of a building. Due to the extended length of the crane’s boom, clearance was required from Stuttgart Airport to execute the lift.
The installation of the 400 MW gas turbine presented another complex challenge. A late requirement specified that its base plate had to be perfectly level due to the construction of its supports. “This is not standard practice for a cargo exceeding 350 ton,” notes Sinelnikov. “Heavy steel rigging typically allows for some tolerances. Massive slings and grommets are never exactly the same length, which would not meet the precise tolerances required by the client.”
To address this, strand jacks were integrated into the crane’s rigging, enabling the team to level the unit during the lift prior to installation. The six stack modules, which combine to form a large chimney, were among the most logistically challenging components to deliver, as they had to be transported via a public road.
These sections were prefabricated offsite and transported using two 12-axle lines of Mammoet self-propelled modular transporters. The team identified the optimal route to minimise site modifications, conducting a 3D scan of the path from the fabrication site to the final installation location.
The modules, measuring up to 18 metres in height and weighing 95 tons, had to be elevated onto a support structure to provide sufficient clearance and reduce on-site preparations. Although the units needed to traverse just 75 metres of public road, a journey that could be completed in minutes, the preparation and planning required several weeks.
A genuine team effort
With numerous complex components needing to be delivered to an active site where multiple contractors were working simultaneously, success rested on meticulous planning, careful execution and clear communication. From the sales and planning teams to the engineers and the project team managing operations on the ground, it was a genuine team effort to deliver this comprehensive end-to-end solution.
For more information contact Jana Wolf, Mammoet, [email protected], www.mammoet.com
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