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Hydro power generation with low water head.
(SL Patent LK/P/1/19066)
The new technology of hydropower generation provides an extension of enclosed pipe into the headwaters from the combination of the intake structure, penstock, and turbine generator. The idea of providing an extended pipe length is to streamline the flow, which is usually coming without speed.
Streams and rivers are constantly moving and adapting to their surroundings. Guided by the force of gravity, these bodies of water carve their way through the earth, shaping the landscape as they go. Despite the resistance from the streambed and banks, the water persists, its velocity dictated by the steepness of the slope, the composition of the terrain, the presence of vegetation, the contour of the stream bed, and any obstructions along the way. Rivers, streams, and creeks serve as vital conduits for runoff, the surplus water that remains after the land has absorbed what it can. Whether it's the result of rainfall, snowmelt, or groundwater discharge, runoff is collected by these waterways as they wind their way through the environment. Their course is a direct reflection of the land they traverse, shaped by the topography and the composition of the soil and rock. With each twist and turn, they breathe life into the landscapes they touch.
Conventionally, hydropower dams are built with their intake bell mouth vertical to the water surface. The introduction of a new device allows the bellmouth to be placed horizontally at the intake of the reservoir, avoiding the need for additional space within the dam structure. When the bell mouth is placed vertically, the pressure of water flow can change due to variations in the water level of the dam. However, when the bell mouth is placed horizontally at the bottom, the pressure of water flow will remain constant.
If the reservoir bed is steep and the intake level is dropped near the dam, a channel or trench can be excavated to extend the pressure pipeline in the horizontal direction, making it easier to install the pressure pipeline inside the reservoir. This can be particularly useful for improving existing hydropower generators with short penstock lengths, by providing additional pipe length inwards to the reservoir from intake.
Revolutionary hydro power
Many dam based hydro power generators were built without providing sufficient length in penstock, between intake and turbine. Most low head, low flow hydro power sources are not exploited since standard hydro power generation techniques cannot be employed in such conditions.
By utilizing this method, we can unveil countless new sites for generating hydropower that were previously untapped by conventional techniques. This presents a distinct advantage, as it enables us to significantly expand our capacity for producing renewable energy and reduce our reliance on non-renewable sources.
Many of today's hydroelectric projects rely on a significant hydraulic head to generate power. This hydraulic head is typically achieved by building a dam in a river bed to create a reservoir. A hydraulic control tower is then constructed at the opposite end of the reservoir, and a pressure pipeline (penstock) is drawn to the powerhouse at the other end.
View of the cross section along the horizontally laid bell mouth
This method can be further diversified to minimize the distance from the hydropower dam by giving a spiral shape to the pressure pipe.
When water enters at the intake, it has no velocity. It needs to gain a certain velocity by the time it reaches the turbine blades. If the intake pipe is extended enough, the streamlined flow can increase the flow speed inside the pipeline. This means that by extending the pipeline into the intake water source, while decreasing the cross section gradually , the flow speed can be increased.
Let us consider the flow of fluid through a pipe having inlet and outlet sectional area are A1, and A2 consecutively. Velocity at two points will be v1 and v2. According to Continuity Equation A1.v1 = A2.v2= Constant
This type of built in pressure pipe is capable of generating a streamline of flow. The sum of dynamic pressure and kinetic pressure will be same at section A-A and section B-B of the streamline flow inside enclosed pipe. Section A-A having a larger area than section B-B. Therefore in this energy system design the speed of flow will increase when it reaches the turbine blades, generating an additional kinetic energy.
Optimization of hydro power for low head turbine
According to present invention, an enclosed penstock (pressure pipe line) is constructed up to the power house, form a suitable distance to generate hydraulic pressure. This hydro power development based on the fact that the flow through closed conduit (pipe) will be greater than flow through an open channel. Water flowing though a closed conduit (pipe) is a lamina flow in a river of a turbulent flow.
Thus, the new technology can be employed to utilize hydro power from rivers having consistency of flow. This technology is inexpensive compared to hydro power projects built with massive hydraulic retaining structures. Sites for this purpose are available in many countries to double the power generating capability of the nation. Therefore this is an affordable and green alternative for small scale waterway sites as well as rivers having large flow without sufficient water head. Also this pressure pipe line optimization technique can be used in existing dams, weirs, waterways and irrigation canals.
Run-off river hydro-electric plants without pond
An application of Pressure pipe optimization technique is illustrated in the run-off river type of hydroelectric power plants is shown below. This construction method based on the fact that water flow though a pipe line will be greater than the free flow of water in a river. Construction of pipe lines to a long distance is highly practical in our times. Thus water of rivers also can be utilize to generate electricity where there is no facility for storing the water. Bringing a part of river flow through the pipeline laid along the river bed would not do any harm to biological inhabitant, chemical characteristics or physical layout of the environment.
Shown above is a longitudinal section and cross section of a river with a consistency of flow where the gradient, conventional hydro power generation methods cannot adopt due the little pressure difference at higher location and the lower location point of the river flow. The water surface pressure at point A and point E are same and equal to atmospheric pressure. River water flow is having some velocity at point "A". Although the point D is a location lower than point "A", velocity of water flow increase by a small value, since it is open channel flow with frictional losses due to uneven surface of river bed and embankments. But the pressure pipe (closed conduit) laid on river bed from point A to point D having reduced in pipe cross section and pressure accumulate at point D that can be applied to generation hydro electric power. The bulb type reaction turbine of Kaplan type is most suitable in such low heads.
Such hydro power generator can be installed at Peradeniya- Sri lanka along Mahaweli River basin without disturbing the environment and without interrupting the natural water flow of the river at the location shown in this picture where 1: Intake point; 3- Pressure pipe line; 2-Bulb type turbine. There's an uninterrupted continues flow along this river though out the year.
The power generator is Shaft-extension type tubular unit.
It requires less space with smaller powerhouse and free discharge without flow interruption due to power house construction. Adjustable Wicket gates are placed at the intake. Runner blades are made adjustable to provide the flexibility to adapt changing head and demand of different power output.At intake point at "A" trash track, flow control gate and fish screen are introduced. In this typical example the turbine and the generator house are separated constructions. Details shown in Figure. 6 are: 1. Water flow coming through penstock, 2. River water flow, 3. Turbine, 4. Power House & 5. Electricity Generator.
Preferably the generator and turbine are housed inside separate chambers while the elongated turbine shaft drives the generator in the power house. The water flow passes in a radial and axial direction through turbine blades to generate power.
This device is published as pdf file
They are suitable for exploitation of tidal power and hydraulic power with low heads such as 2Meters and large flow rates, therefore suitable for generating tidal power as well.
Besides, sending river flow through pressure pipes can prevent flooding in low laying regions.
Impulse turbine
This method is applicable to reservoirs constructed to use impulse turbine as well.
Impulse turbine Parts : 301-Penstock; 302-Hydraulic accumulator; 303-Injector nozzles; 304-Buckets connected with the outer drum; 306- Flanges connected the bracket & runner 308- Bracket connected with the rotor shaft(runner); 309-Runner (Shaft) on bearings
Impulse type turbine applicable with extended tubular passageway is depicted in Figures shown above. This turbine is made to extract energy from jets of water . It defer from the existing impulse type turbines for having the nozzles inject water radially outwards to impel buckets arranged along the outskirt of water wheel circumferentially.
The water carried through extended pipe line integral with penstock 301 is brought to hydraulic accumulator 302 composed of nozzles 303 directed radially outwards. The turbine runner is made integral with articulate buckets 304 concentrically carrying on a wheel around the periphery of a bracket 308 secured to the hub of the runner 309 by flanges 306. The water jets escaping from nozzles impinge on buckets 304 carrying around the periphery of circular bracket 308 and the imparted effect of water jets turns the runner 309 fitted to the turbine shaft 306 mounted on bearings.
Means are provided turbine shaft 306 to couple with electricity generator to produce electrical power. The shape of the buckets ensures that the majority of the kinetic energy is converted into mechanical energy by the turbine. The size of jets is controlled by the needle valves 310 in the center of nozzles303. Means to control the movement of needle are provided from outside. In this design multiple jets of water being directed on to the runner.