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50-467: The hydroelectric power plant is from the Pribran region and uses the water of the reservoir Bileć Lake. The Grančarevo arch dam is double-curved with a perimeter joint. The excavation of the foundation of the dam is 230,000 m3, and the volume of embedded concrete is 376,000 m3. Evacuation of large waters during operation is carried out by an open side overflow of two fields with two segmental closures, which

100-414: A hydrostatic example (first figure), where the hydraulic head is constant, there is no flow. However, if there is a difference in hydraulic head from the top to bottom due to draining from the bottom (second figure), the water will flow downward, due to the difference in head, also called the hydraulic gradient . Even though it is convention to use gauge pressure in the calculation of hydraulic head, it

150-493: A 400 MVA autotransformer and 220/110 kV with a 150 MVA autotransformer with a 400 kV network and a 110 kV network. . The center of the technical information system of the Trebišnjica Hydroelectric Power Plant and the hub of the radio and HF telecommunication systems are located in the switchyard. The machine hall is located 35 meters downstream from the dam, from which it is separated only by the plateau of

200-470: A 400 m deep piezometer, with an elevation of 1000 m, and a depth to water of 100 m: z = 600 m, ψ = 300 m, and h = 900 m. The pressure head can be expressed as: ψ = P γ = P ρ g {\displaystyle \psi ={\frac {P}{\gamma }}={\frac {P}{\rho g}}} where P {\displaystyle P} is the gauge pressure (Force per unit area, often Pa or psi), The pressure head

250-599: A certain RPM can be read from its Q-H curve (flow vs. height). Head is useful in specifying centrifugal pumps because their pumping characteristics tend to be independent of the fluid's density. There are generally four types of head: After free falling through a height h {\displaystyle h} in a vacuum from an initial velocity of 0, a mass will have reached a speed v = 2 g h {\displaystyle v={\sqrt {{2g}{h}}}} where g {\displaystyle g}

300-454: A diffuser, where: Since no pressure forces are created on cylindrical surfaces in the circumferential direction, it is possible to write Eq. (1.10) as: ρ Q ( c 2 u r 2 − c 1 u r 1 ) = M + M τ {\displaystyle \rho Q(c_{2}ur_{2}-c_{1}ur_{1})=M+M_{\tau }} (1.13) Based on Eq. (1.13) Euler developed

350-407: A fluid in a gravitational field is equal to ρg where ρ is the density of the fluid, and g is the gravitational acceleration . On Earth, additional height of fresh water adds a static pressure of about 9.8 kPa per meter (0.098 bar/m) or 0.433 psi per foot of water column height. The static head of a pump is the maximum height (pressure) it can deliver. The capability of the pump at

400-523: A pumping installation is determined by the flow required, the height lifted and the length and friction characteristics of the pipeline. The power required to drive a pump ( P i {\displaystyle P_{i}} ) is defined simply using SI units by: P i = ρ   g   H   Q η {\displaystyle P_{i}={\cfrac {\rho \ g\ H\ Q}{\eta }}} where: The head added by

450-863: Is a vector gradient between two or more hydraulic head measurements over the length of the flow path. For groundwater , it is also called the Darcy slope , since it determines the quantity of a Darcy flux or discharge. It also has applications in open-channel flow where it is also known as stream gradient and can be used to determine whether a reach is gaining or losing energy. A dimensionless hydraulic gradient can be calculated between two points with known head values as: i = d h d l = h 2 − h 1 l e n g t h {\displaystyle i={\frac {dh}{dl}}={\frac {h_{2}-h_{1}}{\mathrm {length} }}} where The hydraulic gradient can be expressed in vector notation, using

500-431: Is a centrifugal pump with two casing chambers and an open impeller. This design is not only used for its self-priming capabilities but also for its degassing effects when pumping two-phase mixtures (air/gas and liquid) for a short time in process engineering or when handling polluted fluids, for example, when draining water from construction pits. This pump type operates without a foot valve and without an evacuation device on

550-540: Is a direct one, an increase in atmospheric pressure is an increase in load on the water in the aquifer, which increases the depth to water (lowers the water level elevation). Pascal first qualitatively observed these effects in the 17th century, and they were more rigorously described by the soil physicist Edgar Buckingham (working for the United States Department of Agriculture (USDA)) using air flow models in 1907. In any real moving fluid, energy

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600-422: Is called a multistage centrifugal pump. The impellers may be mounted on the same shaft or on different shafts. At each stage, the fluid is directed to the center before making its way to the discharge on the outer diameter. For higher pressures at the outlet, impellers can be connected in series. For higher flow output, impellers can be connected in parallel. A common application of the multistage centrifugal pump

650-574: Is commonly used to implement an air handling unit or vacuum cleaner . The reverse function of the centrifugal pump is a water turbine converting potential energy of water pressure into mechanical rotational energy. According to Reti, the first machine that could be characterized as a centrifugal pump was a mud lifting machine which appeared as early as 1475 in a treatise by the Italian Renaissance engineer Francesco di Giorgio Martini . True centrifugal pumps were not developed until

700-445: Is dependent on the density of water, which can vary depending on both the temperature and chemical composition ( salinity , in particular). This means that the hydraulic head calculation is dependent on the density of the water within the piezometer. If one or more hydraulic head measurements are to be compared, they need to be standardized, usually to their fresh water head , which can be calculated as: where The hydraulic gradient

750-498: Is dissipated due to friction ; turbulence dissipates even more energy for high Reynolds number flows. This dissipation, called head loss , is divided into two main categories, "major losses" associated with energy loss per length of pipe, and "minor losses" associated with bends, fittings, valves, etc. The most common equation used to calculate major head losses is the Darcy–Weisbach equation . Older, more empirical approaches are

800-413: Is in a parts washer . In the mineral industry, or in the extraction of oilsand, froth is generated to separate the rich minerals or bitumen from the sand and clays. Froth contains air that tends to block conventional pumps and cause loss of prime. Over history, industry has developed different ways to deal with this problem. In the pulp and paper industry holes are drilled in the impeller. Air escapes to

850-491: Is located on the left side of the dam. A bypass tunnel at the bottom of the right side of the dam can also be used for the eventual need for urgent emptying of the reservoir. 2 main outlets pass through the body of the dam, each with a diameter of 2.5 meters, symmetrically placed on the axis of the dam. Electric energy produced in HPP Trebinje I and HPP Dubrovnik is transmitted with two connecting transmission lines each to

900-508: Is more correct to use absolute pressure (gauge pressure + atmospheric pressure ), since this is truly what drives groundwater flow. Often detailed observations of barometric pressure are not available at each well through time, so this is often disregarded (contributing to large errors at locations where hydraulic gradients are low or the angle between wells is acute.) The effects of changes in atmospheric pressure upon water levels observed in wells has been known for many years. The effect

950-410: Is no risk of leakage, unless the casing is broken. Since the pump shaft is not supported by bearings outside the pump's housing , support inside the pump is provided by bushings. The pump size of a magnetic drive pumps can go from few watts of power to a giant 1 MW. The process of filling the pump with liquid is called priming. All centrifugal pumps require liquid in the liquid casing to prime. If

1000-431: Is present. In addition, a suction-side swing check valve or a vent valve must be fitted to prevent any siphon action and ensure that the fluid remains in the casing when the pump has been stopped. In self-priming centrifugal pumps with a separation chamber the fluid pumped and the entrained air bubbles are pumped into the separation chamber by the impeller action. The air escapes through the pump discharge nozzle whilst

1050-428: Is the boiler feedwater pump . For example, a 350 MW unit would require two feedpumps in parallel. Each feedpump is a multistage centrifugal pump producing 150 L/s at 21 MPa. All energy transferred to the fluid is derived from the mechanical energy driving the impeller. This can be measured at isentropic compression, resulting in a slight temperature increase (in addition to the pressure increase). The energy usage in

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1100-399: Is the acceleration due to gravity. Rearranged as a head : h = v 2 2 g . {\displaystyle h={\frac {v^{2}}{2g}}.} The term v 2 2 g {\displaystyle {\frac {v^{2}}{2g}}} is called the velocity head , expressed as a length measurement. In a flowing fluid, it represents the energy of

1150-547: Is the conservation of the angular momentum (or the “moment of momentum”) which is of fundamental significance to all turbomachines. Accordingly, the change of the angular momentum is equal to the sum of the external moments. Angular momentums ρ Q r c u {\displaystyle \rho Qrcu} at inlet and outlet, an external torque M {\displaystyle M} and friction moments due to shear stresses M τ {\displaystyle M\tau } act on an impeller or

1200-438: Is the same. Magnetically coupled pumps, or magnetic drive pumps, vary from the traditional pumping style, as the motor is coupled to the pump by magnetic means rather than by a direct mechanical shaft. The pump works via a drive magnet, 'driving' the pump rotor, which is magnetically coupled to the primary shaft driven by the motor. They are often used where leakage of the fluid pumped poses a great risk (e.g., aggressive fluid in

1250-399: Is whirled tangentially and radially outward until it leaves through all circumferential parts of the impeller into the diffuser part of the casing. The fluid gains both velocity and pressure while passing through the impeller. The doughnut-shaped diffuser, or scroll, section of the casing decelerates the flow and further increases the pressure. A consequence of Newton's second law of mechanics

1300-633: The Hazen–Williams equation and the Prony equation . For relatively short pipe systems, with a relatively large number of bends and fittings, minor losses can easily exceed major losses. In design, minor losses are usually estimated from tables using coefficients or a simpler and less accurate reduction of minor losses to equivalent length of pipe, a method often used for shortcut calculations of pneumatic conveying lines pressure drop. Centrifugal pump Centrifugal pumps are used to transport fluids by

1350-983: The del operator . This requires a hydraulic head field , which can be practically obtained only from numerical models, such as MODFLOW for groundwater or standard step or HEC-RAS for open channels. In Cartesian coordinates , this can be expressed as: ∇ h = ( ∂ h ∂ x , ∂ h ∂ y , ∂ h ∂ z ) = ∂ h ∂ x i + ∂ h ∂ y j + ∂ h ∂ z k {\displaystyle \nabla h=\left({\frac {\partial h}{\partial x}},{\frac {\partial h}{\partial y}},{\frac {\partial h}{\partial z}}\right)={\frac {\partial h}{\partial x}}\mathbf {i} +{\frac {\partial h}{\partial y}}\mathbf {j} +{\frac {\partial h}{\partial z}}\mathbf {k} } This vector describes

1400-455: The 220 kV busbars of the Trebinje plant. The 220 kV plant was built with two bus systems using the mixed phase method. The connecting field enables the replacement of any switch in the power line or transformer field. With two transmission lines in the direction of TS Mostar 3 and one in the direction of HPP Perućica, the plant is connected to the 220 kV network, via 400/220 kV transformers with

1450-421: The 220 kV outlet from the power plant. It consists of turbine and generator space, rooms for diffuser shutters, control, assembly platform, as well as auxiliary rooms. Number of aggregates installed is 3, powered with 3 x60 MW (180 MW) Francis turbines; network voltage is 220 kV, with average annual production in excess of 370 – 420 GWh Building is 123 m in height and 439 meters in length in crown. Thickness of

1500-413: The back of the impeller and a special expeller discharges the air back to the suction tank. The impeller may also feature special small vanes between the primary vanes called split vanes or secondary vanes. Some pumps may feature a large eye, an inducer or recirculation of pressurized froth from the pump discharge back to the suction to break the bubbles. A centrifugal pump containing two or more impellers

1550-400: The chemical or nuclear industry, or electric shock - garden fountains). Other use cases include when corrosive, combustible, or toxic fluids must be pumped (e.g., hydrochloric acid , sodium hydroxide, sodium hypochlorite, sulfuric acid, ferric/ferrous chloride or nitric acid). They have no direct connection between the motor shaft and the impeller, so no stuffing box or gland is needed. There

Trebinje-1 Hydroelectric Power Station - Misplaced Pages Continue

1600-724: The conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine or electric motor. They are a sub-class of dynamic axisymmetric work-absorbing turbomachinery . The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diffuser or volute chamber (casing), from which it exits. Common uses include water, sewage, agriculture, petroleum, and petrochemical pumping. Centrifugal pumps are often chosen for their high flow rate capabilities, abrasive solution compatibility, mixing potential, as well as their relatively simple engineering. A centrifugal fan

1650-637: The dam at the bottom is 27 and at the top 4.60 meters. Reservoir volume is 1280 hm3 of surface area, at full capacity is 2764 ha. Maximum height difference, the head , is 52 m with concentrated fall of 100 m. Reversible (pumped-storage) Čapljina Hydroelectric Power Station , using Trebišnjica waters through compensation basin Lake Vrutak , was commissioned in 1968. The river Trebišnjca also powers Dubrovnik Hydroelectric Power Station in Croatia, which receiving Trebišnjica waters from Trebinjsko Lake across

1700-503: The direction of the groundwater flow, where negative values indicate flow along the dimension, and zero indicates 'no flow'. As with any other example in physics, energy must flow from high to low, which is why the flow is in the negative gradient. This vector can be used in conjunction with Darcy's law and a tensor of hydraulic conductivity to determine the flux of water in three dimensions. The distribution of hydraulic head through an aquifer determines where groundwater will flow. In

1750-408: The first companies to market a self-priming centrifugal pump was American Marsh in 1938. Centrifugal pumps that are not designed with an internal or external self-priming stage can only start to pump the fluid after the pump has initially been primed with the fluid. Sturdier but slower, their impellers are designed to move liquid, which is far denser than air, leaving them unable to operate when air

1800-489: The fluid drops back down and is once more entrained by the impeller. The suction line is thus continuously evacuated. The design required for such a self-priming feature has an adverse effect on pump efficiency. Also, the dimensions of the separating chamber are relatively large. For these reasons this solution is only adopted for small pumps, e.g. garden pumps. More frequently used types of self-priming pumps are side-channel and water-ring pumps. Another type of self-priming pump

1850-597: The fluid due to its bulk motion. The total hydraulic head of a fluid is composed of pressure head and elevation head . The pressure head is the equivalent gauge pressure of a column of water at the base of the piezometer, and the elevation head is the relative potential energy in terms of an elevation. The head equation , a simplified form of the Bernoulli principle for incompressible fluids, can be expressed as: h = ψ + z {\displaystyle h=\psi +z} where In an example with

1900-698: The head pressure equation created by the impeller see Fig.2.2 Y t h . g = H t = c 2 u . u 2 − c 1 u . u 1 {\displaystyle Yth.g=H_{t}=c_{2}u.u_{2}-c_{1}u.u_{1}} (1) Y t h = 1 / 2 ( u 2 2 − u 1 2 + w 1 2 − w 2 2 + c 2 2 − c 1 2 ) {\displaystyle Yth=1/2(u_{2}^{2}-u_{1}^{2}+w_{1}^{2}-w_{2}^{2}+c_{2}^{2}-c_{1}^{2})} (2) In Eq. (2)

1950-418: The height of an equivalent static column of that fluid. From Bernoulli's principle , the total energy at a given point in a fluid is the kinetic energy associated with the speed of flow of the fluid, plus energy from static pressure in the fluid, plus energy from the height of the fluid relative to an arbitrary datum . Head is expressed in units of distance such as meters or feet. The force per unit volume on

2000-414: The late 17th century, when Denis Papin built one using straight vanes. The curved vane was introduced by British inventor John Appold in 1851. Like most pumps, a centrifugal pump converts rotational energy, often from a motor, to energy in a moving fluid. A portion of the energy goes into kinetic energy of the fluid. Fluid enters axially through eye of the casing, is caught up in the impeller blades, and

2050-416: The piezometer's elevation and screen depth. Hydraulic head can similarly be measured in a column of water using a standpipe piezometer by measuring the height of the water surface in the tube relative to a common datum. The hydraulic head can be used to determine a hydraulic gradient between two or more points. In fluid dynamics , head is a concept that relates the energy in an incompressible fluid to

Trebinje-1 Hydroelectric Power Station - Misplaced Pages Continue

2100-442: The pump ( H {\displaystyle H} ) is a sum of the static lift, the head loss due to friction and any losses due to valves or pipe bends all expressed in metres of fluid. Power is more commonly expressed as kilowatts (10 W, kW) or horsepower (1 hp = 0.746 kW). The value for the pump efficiency, η p u m p {\displaystyle \eta _{pump}} , may be stated for

2150-420: The pump ( H {\displaystyle H} ) is a sum of the static lift, the head loss due to friction and any losses due to valves or pipe bends are all expressed in metres of fluid. Power is more commonly expressed as kilowatts (10 W, kW) or horsepower . The value for the pump efficiency, η pump {\displaystyle \eta _{\textrm {pump}}} , may be stated for

2200-425: The pump casing becomes filled with vapors or gases, the pump impeller becomes gas-bound and incapable of pumping. To ensure that a centrifugal pump remains primed and does not become gas-bound, most centrifugal pumps are located below the level of the source from which the pump is to take its suction. The same effect can be gained by supplying liquid to the pump suction under pressure supplied by another pump placed in

2250-526: The pump itself or as a combined efficiency of the pump and motor system. The energy usage is determined by multiplying the power requirement by the length of time the pump is operating. These are some difficulties faced in centrifugal pumps: An oilfield solids control system needs many centrifugal pumps to sit on or in mud tanks. The types of centrifugal pumps used are sand pumps, submersible slurry pumps, shear pumps, and charging pumps. They are defined for their different functions, but their working principle

2300-439: The pump itself or as a combined efficiency of the pump and motor system. Vertical centrifugal pumps are also referred to as cantilever pumps. They utilize a unique shaft and bearing support configuration that allows the volute to hang in the sump while the bearings are outside the sump. This style of pump uses no stuffing box to seal the shaft but instead utilizes a "throttle bushing". A common application for this style of pump

2350-454: The state border via derivation tunnel. Head (hydraulic) Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum . It is usually measured as a liquid surface elevation, expressed in units of length, at the entrance (or bottom) of a piezometer . In an aquifer , it can be calculated from the depth to water in a piezometric well (a specialized water well ), and given information of

2400-519: The suction line. In normal conditions, common centrifugal pumps are unable to evacuate the air from an inlet line leading to a fluid level whose geodetic altitude is below that of the pump. Self-priming pumps have to be capable of evacuating air from the pump suction line without any external auxiliary devices. Centrifugal pumps with an internal suction stage such as water-jet pumps or side-channel pumps are also classified as self-priming pumps. Self-Priming centrifugal pumps were invented in 1935. One of

2450-481: The sum of 4 front element number call static pressure, the sum of last 2 element number call velocity pressure look carefully on the Fig 2.2 and the detail equation. The color triangle formed by velocity vectors u , c , w {\displaystyle u,c,w} is called the velocity triangle . This rule was helpful to detail Eq.(1) become Eq.(2) and wide explained how the pump works. Fig 2.3 (a) shows

2500-595: The velocity triangle of a forward-curved vane impeller; Fig 2.3 (b) shows the velocity triangle of a radial straight-vane impeller. It illustrates rather clearly energy added to the flow (shown in vector c {\displaystyle c} ) inversely change upon flow rate Q {\displaystyle Q} (shown in vector c m {\displaystyle c_{m}} ). η = ρ . g Q H P m {\displaystyle \eta ={\frac {\rho .gQH}{P_{m}}}} where: The head added by

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