The heavy crane division of Baldwins Industrial Services recently erected the largest exhaust stack of its type in the UK at Shoreham power station. The stack measured 100m high by 7m diameter.
Baldwins’ massive 1,000t-capacity Liebherr LTM 11000D mobile crane, the world’s largest telescopic mobile crane, was used to erect the exhaust stack. The heaviest lifts of the base section weighed approximately 60t. As the height of the stack increased, the weight of the chimney sections decreased, which meant changing the jib configuration during erection.
Directly on the Sussex coastline, the exhaust stack location was very exposed to the elements, and the assembly was hampered by changing wind conditions, which were continuously monitored until a window for erection was available.
The exhaust stack consists of a base section and inlet branch, which were built on site, and five upper sections, all of which were manufactured by Service Welding. The stack was shipped to its location and discharged from the vessel directly on to site. The chimney sections were 14m high with flanged ends. Access to the flanges was via a 160t manbasket crane complete with full fly jib and extensions, all supplied by Baldwins.
The new power station has been built on an existing power station site, which is situated only about 100m from the shoreline, and just a few kilometres along from the south coast resort of Brighton. The exhaust stack is built to represent the stack of the original power station, which was used as a navigation point for ships and aircraft. The new stack has been fitted with aircraft warning lights.
Similarly, the original stack was also home to a nesting falcon, and the new stack has a nesting box at high level installed to give further nesting opportunities.
Inside the new power station itself, main contractor ABB Power Generation has installed six overhead cranes manufactured by Street Crane. Two of these, which were fitted in the turbine hall of the power plant, are double girder cranes with twin hoists of 20t and 70t each. The two cranes largely operate independently, using the hoist that is most appropriate for the load. However, for major sub assemblies weighing up to 123t the cranes operate in tandem using the larger hoists.
Additional cranes include 20t units for the gas compressor, a 10t unit in the pump house, a 7t unit in the cooling water annex and a 6t unit in the workshop. For the gas compressor house crane, special explosion resistant motors and controls were used. The Shoreham contract value for Street was £450,000 ($720,000).
The overhead cranes are to have a double life. First they are being used to help with construction work until the plant is completed and, since they remain in the plant in operating condition, they are also essential maintenance tools to help keep the plant running. Street’s marketing director Keith Rainford explains: “Normally with power stations there are three to four turbines. At any one time one is usually offline, being rebuilt or repaired. This is where the overhead cranes become useful again as part of the ongoing maintenance.” The EOTs at Shoreham feature stepless inverter controls to ensure stable handling of loads. By making acceleration and deceleration as smooth as possible, load swing is minimised and components can be placed more precisely.
Shoreham’s new power station enters service later this year.