EXHIBITIONS
Valve World Expo Düsseldorf 2016: Grist to the valve manufacturer’s mill
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ind and solar power are hot topics at the moment, but
hydropower is currently still the most important source of renewable energy in Europe. In Africa they are also working on securing more supply. The hydroelectric power station of the Grand Inga Dam, for example, which will be built this year and could supply half of the African continent with 40,000 megawatts of energy. Other continents and countries are also changing with the tide.
The Grand Inga Dam on the river Conga is considered Africa’s mega energy project par excellence. A capacity of 4.8 gigawatts has been projected for the end of the first phase (2025). Once the dam is completed it is expected to produce 40 gigawatts. This will make the Grand Inga in the Congo almost twice as large as the world’s largest dam, the Three Gorges Dam in China, which has an annual output equivalent to 30 nuclear power plants.
62 billion euros
for the Grand Inga Dam 62 Billion euros will be invested in the Grand Inga Dam, which is located 150 kilometres off the mouth of the river Congo. The area is considered extremely suitable for energy production because of the steep slope. In order to realise the dam project, the entire river will have to pass through an adjoining valley and be dammed up to 200 metres high.
The project is not without controversy. Critics warn of the ecological consequences of such a massive intervention. Major flood plains could dry up and in other places valuable natural areas will be flooded.
If the plans remain unchanged, 2.5 gigawatts of the first phase
18 IMT June 2016
total of 4.8 gigawatt power will initially go to South Africa. The newly developing country has a rapid growing economy for which it needs abundant energy. Nevertheless all people and industry in Africa are said to benefit from this project. Over 300 million people do not have sufficient access to water and experts predict that the droughts will only continue to increase.
Water Crisis and Energy Transition
More run-of-the-river stations, conventional dams, pumped- storage power plants, tide power stations, as well as plants that use the water’s kinetic energy can help alleviate the global water shortage and contribute significantly to the energy revolution in developing countries. From a technical aspect valves are of course crucial for the flow control, especially shut-off valves.
The Austrian Federal Railways (ÖBB) for example, use hydroelectric power plants as an energy source. The railway-owned power plants are medium and high pressure works with heads ranging from 182 metres to 795 metres. “The water flows from the reservoir and inlet structure over coarse and fine screens to the inlet shut-off devices,” states the national railway company. It then flows through a pipeline to a surge tank. “From the surge tank, the water is guided past shut-off and emergency devices through the penstock –pressure pipeline or pressure shaft – to the power plant.” This is where the water is distributed through piping and shut-off devices, such as ball valves, to the individual turbines. Here the water transfers its energy to the turbine wheels and flows out of the power plant as tailwater or outflow.
The turbines drive single phase
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synchronised generators to produce the single-phase AC. This alternating current is spread over block transformers and a high voltage switch gear to the power supply network, explains the ÖBB.
Different Types of Sealing Multiple types of valves are used in hydroelectric power plants depending on the water quantity, head, and work site. Most common are butterfly valves, spherical valves, cone valves, or ring gates. Butterfly valves are required in hydroelectric power plants with a low and medium pressure range in order to ensure high quality sealing and rapid opening and closing. Spherical valves are mainly used in high pressure applications. Control valves are used in water treatment, distribution systems, as well as hydroelectric power plants.
To avoid operating failure, equipment manufacturers must find all sorts of solutions. For example, the pressure at the intake can cause auto-oscillation, which can damage the penstock. A timely, automated detection of such auto-oscillation can prevent hazards. “By opening or closing a seal the oscillating system is de- tuned and damages due to auto- oscillation can be prevented,” explains Andritz Hydro. This function can either be performed fully automatically or manually after an alarm.
Lots of operational transitions At the hydropower plant Cerro Del Aguila in Peru – a high pressure application – “a substantial improvement” of approximately 15% was recently achieved in the valve head losses by utilising
Photo: Istock©Legate
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