company news about Three Gorges Dam The world's largest hydropower plant

In 2012, the Three Gorges Dam in China took over the #1 spot of the largest hydroelectric dam (in electricity production), replacing the Itaipu hydroelectric power plant in Brazil and Paraguay. The Three Gorges Dam has a generating capacity of 22,500 megawatts (MW) compared to 14,000 MW for the Itaipu Dam. But, over a year-long period, both dams can generate about the same amount of electricity because seasonal variations in water availability on the Yangtze River in China limit power generation at Three Gorges for a number of months during the year.

The height of Three Gorges is about 594 feet (181 meters (m)) and the length is about 7,770 feet (2, 335 m). The dam creates the Three Gorges Reservoir, which has a surface area of about 400 square miles (1,045 square kilometers) and extends upstream from the dam about 370 miles (600 kilometers).
Three Gorges power station had installed 32 units of 700000MW turbines,which is the largest capacity, largest size of Francis generator set. The Francis turbine runner diameter is 10.05m,height 5.99m, total weight 445 ton, 15 blades, each blades weight 17.6 ton. The runner use stainless steel 0Cr13Ni4Mo, weld structure.

Three Gorges Dam due to natural conditions and to the needs of flood control,in preliminary stage，water head is 61-94 meters, final stage,water head is 71-113 meters, before the flood season every year, reservoir water level dropped to 145 meters elevation, flood control capacity of 22.15 billion cubic meters, water head has great variation, rated head 80.6 meters, this increased the difficulty turbine design. Each turbine set is mainly composed of water conduit pipe, stand ring, spiral case, distributor, runner, main shaft, lower bracket, head cover, rotor bracket, stator core, the stator winding, draft tube and other components. Single turbine generator unit output is 700MW, turbine runner nominal diameter is 9.709 / 10.427m (VGS / Alstom type), is the world's largest Francis turbine runner. The turbine generator unit uses three guide bearing, semi-umbrella structure type, the thrust bearing is load 5050/5520 tons, which is greatest in today's world. Generator rated output is 778MVA, power factor 0.9. In order to improve the stability of the turbine running under high water head, the turbine design maximum output 840MVA, can operation continuously . The Generator rated voltage 20kV, using water-cooled stator winding and air cooling rotor. The outside diameter of Generator stator frame is 21.42 / 20.9m, the inner diameter of the stator core is 18.5 / 18.8m, height of core is 3.13 / 2.95m, weight of each turbine about 7000 tons, are the largest in the world.

Three Gorges Right Bank Power Station have 12 pressure water pipe, largest diameter is 12.8 m, connect to 12 turbine generators in the right bank power house at the bottom of dam.
1, the turbine inlet pipe
Each unit has a diameter of 12.8 meters large steel water pipes extending from the inlet to the downstream of Turbine spiral case front portion, is poured in the concrete dam. Pipe is composed of 72 section, include uphill straight section, recurved segments and lower planar sections , and gradual taper pipe sections four parts, made of thickness 26-60mm 60kgf / mm2 class high strength steel. weight of each section between 20-50 tons.
three Gorges reservoir water through the inlet of steel gate on dam, into the water pipe,pouring down by 1020 cubic meters per second, and then into a circular spiral rotary motion to create a strong impact, adjust by water distributor, into the turbine runner evenly and shaft symmetrically, push the runner blade rotation. Water pipe also under tremendous pressure from the 39.3 billion cubic meters of water in the reservoir.

So the steel yield strength, tensile strength, elongation properties and impact toughness of water pipes have strict requirements.