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## Hydro power plants

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**Hydro power plants**Inlet gate Air inlet Surge shaft Penstock Tunnel Sand trap Trash rack Self closing valve Tail water Main valve Turbine Draft tube Draft tube gate**The principle the water conduits of a traditional high head**power plant**Ulla- Førre**Original figur ved Statkraft Vestlandsverkene**Ligga Power Plant, Norrbotten, Sweden**H = 39 m Q = 513 m3/s P = 182 MW Drunner=7,5 m**Borcha Power Plant, Turkey**H = 87,5 m P = 150 MW Drunner=5,5 m**Water intake**• Dam • Coarse trash rack • Intake gate • Sediment settling basement**Dams**• Rockfill dams • Pilar og platedammer • Hvelvdammer**Rock-fill dams**• Core Moraine, crushed soft rock, concrete, asphalt • Filter zone Sandy gravel • Transition zone Fine blasted rock • Supporting shell Blasted rock**Types of Gates**• Radial Gates • Wheel Gates • Slide Gates • Flap Gates • Rubber Gates**Radial Gate**The forces acting on the arc will be transferred to the bearing**Slide Gate**Jhimruk Power Plant, Nepal**Rubber gate**Flow disturbance Reinforced rubber Open position Reinforced rubber Closed position Bracket Air inlet**Circular gate**End cover Hinge Ribs Manhole Pipe Ladder Bolt Fastening element Seal Frame**Circular gate**Jhimruk Power Plant, Nepal**Trash Racks**Panauti Power Plant, Nepal**Gravfoss**Power Plant Norway Trash Rack size: Width: 12 meter Height: 13 meter Stainless Steel**CompRack**Trash Rack delivered by VA-Tech**Pipes**• Materials • Calculation of the change of length due to the change of the temperature • Calculation of the head loss • Calculation of maximum pressure • Static pressure • Water hammer • Calculation of the pipe thickness • Calculation of the economical correct diameter • Calculation of the forces acting on the anchors**Materials**• Steel • Polyethylene, PE • Glass-fibre reinforced Unsaturated Polyesterplastic , GUP • Wood • Concrete**Wood Pipes**Breivikbotn Power Plant, Norway Øvre Porsa Power Plant, Norway**Calculation of the change of length due to the change of the**temperature Where: DL = Change of length [m] L = Length [m] a = Coefficient of thermal expansion [m/oC m] DT = Change of temperature [oC]**Calculation of the head loss**Where: hf = Head loss [m] f = Friction factor [ - ] L = Length of pipe [m] D = Diameter of the pipe [m] c = Water velocity [m/s] g = Gravity [m/s2]**ExampleCalculation of the head loss**Power Plant data: H = 100 m Head Q = 10 m3/s Flow Rate L = 1000 m Length of pipe D = 2,0 m Diameter of the pipe The pipe material is steel Where: c = 3,2 m/s Water velocity n = 1,308·10-6 m2/s Kinetic viscosity Re = 4,9 ·106 Reynolds number**Where:**Re = 4,9 ·106 Reynolds number e = 0,045 mm Roughness D = 2,0 m Diameter of the pipe e/D = 2,25 ·10-5 Relative roughness f = 0,013 Friction factor The pipe material is steel 0,013**ExampleCalculation of the head loss**Power Plant data: H = 100 m Head Q = 10 m3/s Flow Rate L = 1000 m Length of pipe D = 2,0 m Diameter of the pipe The pipe material is steel Where: f = 0,013 Friction factor c = 3,2 m/s Water velocity g = 9,82 m/s2 Gravity**Calculation of maximum pressure**• Static head, Hgr(Gross Head) • Water hammer, Dhwh • Deflection between pipe supports • Friction in the axial direction Hgr**Maximum pressure rise due to the Water Hammer**Jowkowsky Dhwh = Pressure rise due to water hammer [mWC] a = Speed of sound in the penstock [m/s] cmax = maximum velocity [m/s] g = gravity [m/s2] c**ExampleJowkowsky**a = 1000 [m/s] cmax = 10 [m/s] g = 9,81 [m/s2] c=10 m/s**C**L Maximum pressure rise due to the Water Hammer Where: Dhwh = Pressure rise due to water hammer [mWC] a = Speed of sound in the penstock [m/s] cmax = maximum velocity [m/s] g = gravity [m/s2] L = Length [m] TC = Time to close the main valve or guide vanes [s]**Example**L = 300 [m] TC = 10 [s] cmax = 10 [m/s] g = 9,81 [m/s2] C=10 m/s L**st**st p ri t Calculation of the pipe thickness • Based on: • Material properties • Pressure from: • Water hammer • Static head Where: L = Length of the pipe [m] Di = Inner diameter of the pipe [m] p = Pressure inside the pipe [Pa] st = Stresses in the pipe material [Pa] t = Thickness of the pipe [m] Cs = Coefficient of safety [ - ] r = Density of the water [kg/m3] Hgr = Gross Head [m] Dhwh = Pressure rise due to water hammer [m]**st**st p ri t ExampleCalculation of the pipe thickness • Based on: • Material properties • Pressure from: • Water hammer • Static head Where: L = 0,001 m Length of the pipe Di = 2,0 m Inner diameter of the pipe st = 206 MPa Stresses in the pipe material r = 1000 kg/m3 Density of the water Cs = 1,2 Coefficient of safety Hgr = 100 m Gross Head Dhwh = 61 m Pressure rise due to water hammer**Calculation of the economical correct diameter of the pipe**Total costs, Ktot Cost [$] Installation costs, Kt Costs for hydraulic losses, Kf Diameter [m]**ExampleCalculation of the economical correct diameter of the**pipeHydraulic Losses Power Plant data: H = 100 m Head Q = 10 m3/s Flow Rate hplant = 85 % Plant efficiency L = 1000 m Length of pipe Where: PLoss = Loss of power due to the head loss [W] r = Density of the water [kg/m3] g = gravity [m/s2] Q = Flow rate [m3/s] hf = Head loss [m] f = Friction factor [ - ] L = Length of pipe [m] r = Radius of the pipe [m] C2 = Calculation coefficient**ExampleCalculation of the economical correct diameter of the**pipeCost of the Hydraulic Losses per year Where: Kf = Cost for the hydraulic losses [€] PLoss = Loss of power due to the head loss [W] T = Energy production time [h/year] kWhprice = Energy price [€/kWh] r = Radius of the pipe [m] C2 = Calculation coefficient**ExampleCalculation of the economical correct diameter of the**pipePresent value of the Hydraulic Losses per year Where: Kf = Cost for the hydraulic losses [€] T = Energy production time [h/year] kWhprice = Energy price [€/kWh] r = Radius of the pipe [m] C2 = Calculation coefficient Present value for 20 year of operation: Where: Kf pv = Present value of the hydraulic losses [€] n = Lifetime, (Number of year ) [-] I = Interest rate [-]