Hall cranes supplied for main power generation plants

28th February 2014

  

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Lifting company Konecranes is responsible for the pro- vision and erection of the main turbine hall cranes at State-owned electricity utility Eskom’s critically important Medupi, Kusile and Ingula power plants, says Konecranes service, sales and marketing director John MacDonald.

The parastatal’s Medupi and Kusile plants are Eskom’s two latest coal-fired power stations, and Ingula is its most recent hydroelectric power plant. Altogether, four 120/50 t cranes and two 265 t overhead cranes were installed at these power stations.

Eskom will be exhibiting at Power-Gen Africa 2014, to be held in Cape Town, from March 17 to 19.

MacDonald adds that cranes and other lifting equipment are an important aspect at power generation plants, especially during the erection phase and in the maintenance process. To deal with the unique demands of the power industry, cranes and lifting equipment must be able to operate in demanding environments with precision, safety and absolute reliability.

The range comprises, among others, turbine hall cranes that facilitate the installation and accurate adjustment of turbines, generators and auxiliaries; coal handling cranes with clamshell buckets; compact, lightweight chain hoists that provide fast hoisting speeds inside wind turbine nacelles; and intake gantry cranes for lifting the gates of hydroelectric dams, he says.


Medupi Power Station

Medupi, valued at R105-billion, is located on an 883 ha site in Lephalale, Limpopo. It will be a dry-cooled, coal-fired, baseload power-generating plant, comprising six 794 MW units, with a 4 764 MW installed capacity – the biggest of its kind with dry cooling, with a planned operational life of 50 years.

The power station will use high-tech supercritical boilers, which will operate at higher temperatures and pressures than the older boilers, thereby providing greater efficiency.

It is the first baseload coal-fired station to be built in South Africa in more than 20 years and its delivery on schedule is viewed as critical.

Kusile Power Station

Kusile, which is being developed at a cost of R118.5-billion, is a six-unit, greenfield, mine-mouth, supercritical coal-fired power plant, with about 4 800 MW of gross output. It is built adjacent to the existing Kendal power station, in the eMalahleni municipal area.

The Kusile project includes a power station precinct, power station buildings, administrative buildings (control buildings and buildings for medical and security purposes), roads and a high-voltage yard.

The associated infrastructure includes a coal stockyard, coal and ash conveyors, temporary and permanent water-supply pipelines, temporary electricity supply during construction, water and wastewater-treatment facilities, ash disposal systems, a railway line, limestone offloading facilities, access roads (including haul roads) and dams for water storage, as well as a railway siding and/or a line for the sorbent (limestone) supply.

The unit is the first power station in South Africa to install flue gas desulphurisation – a state-of-the-art technology used to remove oxides of sulphur, such as sulphur dioxide, from exhaust flue gases in power plants that burn coal.

The plant uses an air-cooling system to help conserve water. Kusile is the largest dry-cooled power plant in Africa. A total of 16 000 t of structural steel was used for the first unit’s boiler construction and it is expected that 115 400 t of structural steel will be used for all six units.

To date, more than 600 000 m3 of concrete has been used at the site. Kusile has one of the largest concrete batch plants in South Africa. The operational life of the power station is expected to be 60 years. The total estimated cabling to be installed for each Kusile unit is 1 000 km.

The operational life of the power plant is expected to be 60 years.

Ingula Pumped-Storage Scheme

The Ingula pumped-storage scheme, located within the Little Drakensberg mountain range, 23 km north-east of Van Reenen’s Pass, will comprise an upper dam (Bedford) and a lower dam (Braamhoek). The upper reservoir site is located in the Free State and the lower reservoir site in KwaZulu-Natal. The escarpment forms the border between the two provinces.

The distance between the upper and lower reservoirs will be 4.6 km, with an elevation difference of about 470 m.

The dams will be connected through underground waterways using an underground powerhouse complex, which will house four 333 MW pump turbines with a total capacity of 1 332 MW, a machine hall, a transformer hall and associated tunnels, shafts and caverns.

The twin waterways, consisting of concrete and steel-lined headrace tunnels, pressure tunnels and shafts, will link the upper reservoir with the pump and turbines. Steel-lined extended draft tubes and a single concrete-lined tailrace tunnel will connect the pump and turbines to the lower reservoir.

The upper reservoir will be a concrete-faced rockfill embankment dam, 41 m high, with a total capacity of 22.6-million cubic metres and an active water storage volume of 19.3-million cubic metres. The 39-m-high lower dam will be of roller-compacted concrete, with a total capacity of 26.3-million cubic metres and an active storage volume of 21.9-million cubic metres.

The upper reservoir will store enough water to generate electricity continuously using all four units for 16 hours. Pumping the water back from the lower reservoir will take about 21 hours, giving an overall efficiency of 76% for the scheme.

Edited by Megan van Wyngaardt
Creamer Media Contributing Editor Online

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