Respond to every call that excites your spirit. Rumi
Idea Transcript
Francis Turbines Noelle Fillo, Kimberly Fridsma, Callen Hecker
History ●
Developed by James B. Francis in Lowell, Massachusetts ○ ○ ○
●
●
Founded ASCE Locks and Canals company 1848
The first Francis turbine was housed in the Pawtucket Gatehouse in Lowell, MA. He based his designs off of other turbines that were designed around that time.
Design based off of Benoit Foureyron’s outwardflow turbine and Jean-Victor Poncelet’s inwardflow turbine. Can be used in a variety of hydraulic heads and flow levels Francis Turbines are a reaction turbine First hydraulic turbine with radial inflow
Water flows through spiral casing, runners, guide vanes and exits out turbine eye Pressure differences caused by blade shape allow for rotation and draws water towards center Guide vane angles are manipulated to optimize flow
CFD images showing high velocities near eye and blade edges
Pressure differences caused by flow create vortices that damage surfaces Indicated by a popping noise Static pressure must not go below vapor pressure Flow separation at turbine exit must be avoided to avoid draft tube damage Must control for: ○ ○ ○
Pressure head Flow rate Exit Pressure
Advantages of Francis Turbines ● ● ● ●
Francis turbines work best for medium to high range heads Easily controlled operating head Francis turbines operate over the largest range for both flow and head parameters Large range in size to meet different power requirements ○
●
Range from 0.25 MW to 1000 MW
High efficiency ○
Generally around 94%
Operative ranges of different turbines http://www.gunt. de/networks/gunt/sites/s1/mmcontent/produktbilder/07036531/Datenblatt/07036531%202. pdf
Advantages ● ● ●
Francis turbines are mixed flow designs Francis turbines have the highest maximum power for turbines Francis vs. Pelton ○ Smaller and more economical than a Pelton wheel capable of the same power generation ○ More resistant to wear than the Pelton wheel ○ Francis turbines have higher levels of efficiency
http://www.gunt. de/networks/gunt/sites/s1/mmcontent/produktbilder/07036531/Datenblatt/07036531%202. pdf
Disadvantages ● ●
Unclean water can cause rapid wear in Francis turbines Cavitation is always a possibility ○ ○
● ● ● ●
Runner erosion Losses in efficiency
Effects of cavitation on runner http://authors.library.caltech.edu/25019/1/chap6.htm
Difficult to maintain and clean Low acceptance of head variation Constant adjustment of guide vanes and runners Francis turbines are generally limited to large hydroelectric systems
Possible cavitation areas on the runner http://www.diva-portal.org/smash/get/diva2:741702/FULLTEXT01.pdf
Disadvantages ●
Francis turbine efficiency significantly decreases with turbine flow rates below 40% ○
●
Decreased flow also greatly increases cavitation risk
Water hammer effect can cause harmful effects ○
Occurs when runners are forced from high speed to stopping
○
Build up of overpressures can cause catastrophic results
Example A Francis turbine is to be operated at a speed of 600 rpm and with a discharge of 4.0 m3/s. If r1 = 0.60 m, β1 = 110⁰, and the blade height B is 10 cm, what should be the guide vane angle α1 for a nonseparating flow condition at the runner entrance?
Case Study I- Itaipu Dam in Brazil/Paraguay ● ● ● ● ● ●
Located on the Parana River between Brazil and Paraguay One of the Seven Wonders of the Modern World Second largest hydroelectric power plant 87.8 TWh generated in 2014 118m of hydraulic head 20 Francis turbines ○ ○
●
700 MW each 16 m diameter
Average reservoir capacity ○
19x109 m3
http://www.solar.coppe.ufrj.br/itaipu.html
Case Study II- Guri Hydroelectric Power Plant in Orinoco, Venezuela ● ●
● ●
On the Caroni River in Necuima Canyon in Orioco, Venezuela Installed capacity of 10,200 MW and provides 12,900 GW/h to the country Ten 730MW Francis Turbines Third largest power plant in the world
Case Study III- Vertical Twin Turbines in Australian Irrigation Dams ● ● ● ●
Used in Wyangala, Copeton and Burrendong irrigation dams Smaller turbines, but useful for privately developed hydro schemes Desirable when head is too high for a Kaplan turbine Ideal when: ○ ○
Fish-Friendly Francis Turbine Design Do not allow cavitation to occur Direct migratory fish away from turbines ● Low number of blades with thick edges ● Wide wicket gate-runner gaps, ● Wicket gates aligned with stay vanes ● Smooth surfaces provided ● Use advanced control system and monitor speeds ● Minimize pressure changes experienced by fish http://www1.eere.energy. http://www.westcoast.fisheries.noaa. gov/wind/pdfs/doewater-13741. gov/images/hydropower/newandoldturbinedesign_102313.gif pdf ● ●
Conclusions ●
● ● ● ●
Francis turbines are one of the most widely used turbines of our time Extremely high efficiency at specific flows Come in many sizes and are very versatile Large range of power outputs Wanted when dealing with relatively medium head and high flows