![]() Here, the intake length is kept quite short and leads to either a vertical axis Kaplan turbine or a horizontal axis bulb turbine (Figure 4).įIGURE 4. These are used for powerhouses located across rivers or canals to utilize the head difference across a canal drop. (a) Power canal leading to fore-bay at head of turbine unit, (b) Detail ‘A of head regulator for canals in hilly region equipped with silt deflector for preventing boulder entry & settling tank to remove sediment that too entered the canal. Intake adjacent to a barrage leading to a canal (a) Plan (b) Section through head regulatorįigure 3. ![]() Intake adjacent to a barrage leading to a tunnel (a) Plan, (b) Section X-Xįigure 2. There is also a Bye-Pass Channel to release water when the turbines shut down suddenly.įigure 1. The exit passage from the turbines is called the Tail Race Channel. It may be observed from Figure 3 that the canal conveying water, also called the power canal, leads to a Forebay before leading to the turbine unit. For a canal intake (Figure 2), the head regulator resembles that of an irrigation canal intake. Here, an intake for a tunnel is placed upstream of the diversion structure to draw water from the pool (Figure 1). Intakes adjacent to a diversion structure like a barrage.For each one of these hydropower projects, there are a few different types, the important ones of which are explained in the following paragraphs. The position and location of an intake in a hydropower project would generally depend upon the type of hydropower development, that is, whether the project is of run-of-river type or storage type. Floating material should not enter the water conducting system.There should be minimum entry of sediment into the water conducting system.There should not be any formation of vortices that could draw air into the water conducting system.There should be minimum head loss as water enters from the reservoir behind a dam or the pool behind a barrage into the water conducting system.It is designed such that the following points are complied, as far as possible: This chapter discusses the important issues related to the different components of a hydropower Water Conveyance System.Īn intake is provided at the mouth of a water conveyance system for a hydropower project. For open channel systems, this may lead to generation of surges in the water surface which may even cause spillage of the channel banks if adequate freeboard is not provided. If the closure is relatively fast, high pressures may develop in pressured systems conducting water to the turbine. In either of the above cases, some provision is usually made to prevent the undesirable effects of a power rejection in the generator that may cause the turbine to spin exceedingly fast, resulting in a closure of the valves controlling the flow of water at the turbine end. ![]() High-pressure conduits, commonly called the penstocks.In the pressure flow system, there could be further classification into the two types, as: The water conducting system, again, may be of two types Outflow structure, which is usually a part of the turbine tail end.Water conducting system comprising of different structures.The main components of a water conveyance system consists of the following: Apart from these, floating materials like trees or dead animals and in some projects in the higher altitudes ice blocks may get sucked into the system which may clog the turbine runners. The bigger particles may choke the system whereas the smaller ones may erode the turbine blades by abrasive action. The energy of the inflowing water may be preserved, as far as possible, throughout the water course so that the turbine-generator system may extract the maximum possible energy out of the flowing water.Īs an example of the first case, it may be cited that in hilly rivers, there are good chances of sand, gravel, and even boulders getting into the water conducting system along with the flowing water.The water inflowing into the conveyance system should be free from undesirable material, as far as possible, that may likely damage the turbines or the water conducting system itself.Right from the intake of the water conducting system, where water enters from the main river, up to the outlet where water discharges off back into the river again, different structural arrangements are provided to fulfil certain objectives, the important ones being as follows: A dam or diversion structure like a barrage obstructs the flow of a river and creates a potential head which is utilized by allowing the water to flow through the water conducting system upto the turbines driving the generators and then allowing it to discharge into the river downstream.
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