Showing posts with label Francis Turbine. Show all posts
Showing posts with label Francis Turbine. Show all posts

Sunday, April 24, 2016

Francis Turbine

Horizontal Francis Hydro Turbine / Francis Water Turbine with Water Head From 20m to 300m

Francis turbines are most widely used among water head from 20m to 700mm. A Francis turbine has a runner with fixed blade, usually nine or more. Water is introduced just above the runner and all around it and then falls through, causing it to spin. Besides the runner, the other major components are the spiral case, wicket gates, and draft tube. Most small Francis turbine are horizontal shaft and metallic spiral case, it has two bearing assembled on the generator seat.

Water flows through penstock of the power station, Butterfly valve, expansion pipe, inlet tube, spiral case and wicket gates into the runner, and then it drives the runner to revolve and convert hydraulic energy into mechanical energy and drives the rotor of generator revolution by the force of the main shaft of turbine, thus converting the mechanical energy into electric energy.

Franics Turbine runner compose of the  blade, upper crown, bend and cone.
The whole rotating part is mainly composed of the runner, main shaft, flywheel and main sealing assembly etc. The main shaft is laid in horizontal or vertical  position. The runner cone is keyed on the end of the main shaft, and locked with bolt, The other  end of the main shaft is connected to the flywheel. The runner is the principal component of the turbine convert hydraulic energy into mechanical energy. The main sealing assembly adopts polyethylene packing structure to prevent water leaking out, and should be connected the clean and pressure water which pressure is 0.15~0.25MPa.

Spiral case

The spiral casing is the largest part of the hydraulic turbine and erecting bench- mark. It is made of steel-welding structure. Together with spiral casing and stay ring. Some stay vanes are equipped on the inner of stay ring. A pressure gauge is equipped to measure the pressure of the inlet water there. On the top of the spiral casing, it presents an air-discharge valve, which is used to expel out the residual air in the shell, when the shell is filled with water before starting up the turbine.

The distributor consists of wicket gates, guide vane arms, shear pins, regulating ring, head cover, bottom ring etc.
 The wicket gates  function is to regulate the discharge of water flow. so as to suit the regulation on various loads.
 The opening of wicket gates can be regulated by the governor servomotor, to guarantee the revolving speed constant when the load changes. When the turbine is shut down all openings between the wicket from flowing into the runner. Each wicket gate swivels in bushing along, the axial line of its stem. The lower bushing seats in the head cover, the middle and upper bushing seat in the bottom ring. The connecting rod mechanism is equipped between the wicket gates and regulating ring in order to transfers their move and force.
Also the  shear pins are equipped on the distributor. When the turbine is shut down if the closing of the wicket gates exists obstacles, the shear pin related to the opening will be shorn so that the other pats of distributor many not be damaged. The regulating ring is connected with the servomotor by way of the connecting rod.

The draft tube  consists of draft tube, draft tube cone and draft tube bend etc. It’s function is to guide water current and receive some hydraulic energy.

XILUODU hydropower station

China's second largest hydropower station
-XILUODU hydropower station

Project total investment:79.2 Billion Yuan
Engineering period: 2005-2015

Xiluodu hydropower station is located in Qinghai-Tibet Plateau, Yunnan-Guizhou Plateau to the Sichuan Basin transition zone, located in Xiluodu Gorge, where bordering Leibo County, Sichuan Province and Yongshan County, Yunnan Province,  Xiluodu Hydropower Station is the largest of the four giant hydropower station on Jinsha River, Capacity quite with the Itaipu,the world's second largest hydropower installed capacity is 12.6 million kilowatts, Annual generation capacity ranked third in the world,is 571.2 billion KWh, equal to Itaipu hydropower station, and three and a half of the Gezhou Dam, is the second largest hydropower station in China.

Xiluodu hydropower station is the closest key power of China “west to east power transmission project” on Jinsha river, also the largest hydropower station on Jinsha river.

Jinsha river is upper stream of Yangtze river,total length 3364 kilometer, drainage area 473.2 thousand Jinsha river has abundant water resources, reserves energy reached 112.4 million kilowatts,  accounted for 1/6 of the total hydropower in China.

This project located in Xiluodu Gorge, where bordering Leibo County, Sichuan Province and Yongshan County, Yunnan Province, downstream of Jinsha river. The project use concrete double curvature arch dam,dam height 278m, normal storage water level 600m, total storage 11.57 billion cubic meters,
Regulation storage 6.46 billion cubic meters, installed capacity 12.6 million KW, average annual generating capacity of 57.12 billion KWH, the project static investment 45.928 billion Yuan, total 79.234 billion Yuan. Project feasibility design finished on Dec. 2001, start building on Dec.2005, on Jun.2013, the first set of generator put into operation, and whole project completed on 2015.

Xiluodu Hydropower station use vertical Francis hydro turbine, manufacturer Voith, rated water head 197m, max. Head 229.4m, min. Head 154.6m, weighted average of the head 223.48m, rated flow 430.5 cubic meter per second, rated output power 784 Megawatt, rated speed 125 r/min,suction head HS=-10.81m, installation elevation 359m. Francis runner diameter is 7.4m, max. Outer diameter 7.755m, height 3.462m, each runner weight 179 ton.
Material is stainless steel 0Cr13Ni4Mo.  
When Xiluodu hydropower plant was fully connected to the grid in June 2014, it started with a nominal capacity of 13.86 gigawatts. All in all, 18 machine units are in operation. This made it the world's third largest hydropower plant. The plant will help to reduce air pollution thanks to the renewable electricity production of Xiluodu: The annual consumption of coal will be cut down by 41 million tons. In addition to that, exhaust gas emissions will be reduced by nearly 150 million tons of CO2, 480,000 tons of nitrogen dioxide and 850,000 tons of sulfur dioxide per year.
Another advantage of Xiluodu is the ability to deliver base load in large quantity. Xiluodu can produce as much energy around the clock as 14 large thermal or nuclear power plants. As a matter of fact, hydropower technology can bridge the gap between the enormous demand of electricity, and, on the other hand, meet the emission targets our societies have committed themselves to.

panoramic photo of Construction site:

Closure photo of the Xiluodu Dam
Dam photo:

 Spiral case photo:
 spiral case welding:
 Draft tube tunnel construction
 spiral case installation
 Francis turbine runner
 generator rotor isntallation
 generator stator assembly
night scene of XILUODU

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