Methods for transferring sediment in a body of water

Abstract

Method for transferring sediment in a body of water (1), wherein at least one additional water turbine (8) is provided and installed prior to the actual sediment transfer, and during the subsequent sediment transfer, the sediment-water mixture which passes through a water turbine during the transfer passes exclusively through the additional water turbine (8).

Description

The present invention relates to a method for transferring sediment in a body of water, wherein the body of water is part of a water path in which a water power plant is located. In this case, the water body generally comprises an upper water which is threatening to land.Methods for transferring sediment in a body of water are carried out in parts of bodies of water which are threatening to land. These are bodies of water which are accumulated in any form or which have an outflow which, due to nature, is unsuitable for adequately removing the quantity of sediment produced. In particular, parts of bodies of water on which hydroelectric power plants are located are often threatening to land. These also include pumped storage power plants with a natural upper basin, storage power plants and running water power plants. Most sediments are introduced by natural inflows into the part of the water which is threatened by the landing. In addition to combat the landing, such a method has a further advantage in that the sediment permeability of hydroelectric power plants is restored.DE 10 2020 108 520 A1 discloses such a method in which a sediment-water mixture is transferred from the surface water into the surface water through a water power plant, wherein the maximum permissible sediment quantity introduced into the connecting line to the water power plant depends on the current operating mode of the water power plant. An advantage of the disclosed method is that the water which is required for producing the sediment-water mixture can be used for the energy generation by the hydroelectric power plant. However, since the maximum permissible amount of sediment is dependent on the mode of operation of the hydroelectric power plant, it may occur that, over longer periods of time, the sediment transfer must proceed at a transfer rate which is below the maximum transfer rate possible with the means used. In addition, it may happen that after completion of the sediment transfer, the turbines of the hydroelectric power plant have been damaged by erosion. The evidence that the damage observed has not been caused by the sediment transfer can be very difficult.The object of the invention is to specify a method for transferring sediment in a body of water which avoids the disadvantages mentioned without sacrificing the advantages mentioned.The object is achieved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention are found in the dependent claims.The invention is explained below with reference to figures. The figures show in detail: FIG. 1 : arrangement according to the prior art; FIG. 2 : Arrangement for carrying out the method according to the invention in a first embodiment; FIG. 3 : Arrangement for carrying out the method according to the invention in a second embodiment;FIG. 1 shows a highly schematic representation of a body of water on which the method known from the prior art is carried out. The water body is designated by 1. The body of water generally comprises an upper water, which is designated 7. Under surface water, each part of the water is jointly understood, which is accumulated or built up in some form. It can therefore also simply be a section of a flowing water which is arranged upstream of a hydroelectric power plant. The body of water 1 further comprises an underwater. Between surface 7 and surface there is a water power plant which is designated 2. The hydroelectric power plant 2 comprises at least one water engine.In the surface 7 there is arranged a discharge element which is designated 3. The discharge element 3 can be designed differently, for example as a discharge in the vicinity of the bottom of the body of water, as an opening in a retaining wall or as an inlet of any desired design for a water power plant (for example as an inlet rake). The discharge element 3 is connected to the water power plant 2 by means of a connecting line, which is designated 6, in such a way that water can flow from the surface 7 through the connecting line 6 to the water power plant. The water passes through the water power plant 2 into the underwater, which is not shown in FIG. 1. The arrow indicates the direction toward the subsea. If the hydroelectric power plant 2 is a pumped storage power plant, then the water can naturally also flow in the opposite direction during pumping, i.e. from the underwater to the surface 7. However, this can also be a channel or another water path.FIG. 1 also shows a device for providing a sediment-water mixture, which is denoted by 4. The device 4 is connected to the connecting line 6 between the surface water 7 and the hydroelectric power plant 2 in such a way that the sediment-water mixture provided by the device 4 can be introduced into the connecting line 6 and can thus be discharged into the underwater through the hydroelectric power plant 2 by the water flow in the connecting line 6.First, in the known method, sediment is absorbed in the surface water 7. Thereafter, the absorbed sediment is transferred to the device 4 in order to finally be introduced into the connecting line 6 in the form of the said sediment-water mixture provided by the device 4. In this way, a sediment transfer occurs within the body of water 1, i.e. from the surface water 7 into the underwater through the hydroelectric power plant 2. The sediment-water mixture passes through at least one water engine installed in the water power plant.The device 4 for providing a sediment-water mixture is arranged anywhere in, at or near the dust corner 7. The device 4 for providing a sediment-water mixture can be, for example, a device that can be moved on the body of water 1, as described in WO 2019 / 161996 A1. However, the device 4 could just as well be arranged on the bottom of the water body, on the shore of the dust corner 7 or on a structure in the water body 1. In any case, the sediment-water mixture provided by the device 4 is introduced into the connecting line 6. This can be effected, for example, by a line which extends from the device 4 to the discharge element 3, into which this line opens, as shown in FIG. 1.The sediment-water mixture provided by the device 4 consists of sediment and water which have been taken up or removed from the surface water 7. The drawing-up or removal can be carried out as described in WO 2019 / 161996 A1, wherein the sediment-water mixture is generated directly during the drawing-up or removal. The device 4 has the means described in the cited document. Sediment and water can also be taken off separately in each case just as well. For example, by removing sediment from the dust corners 7 by a floating excavator, e.g. a shovel or a submarine, and supplying it to the device 4, for example by means of a further floating device. The water for the mixture can be pumped, for example, simply from the body of water 1. The device 4 then generates the sediment-water mixture by mixing the individual components, wherein the device must have suitable means for this purpose in this case. This can include, for example, a container for storing sediment, into which the floating device periodically introduces sediment.To carry out the known method, the device 4 has means for controlling the sediment concentration in the provided sediment-water mixture. The sediment concentration can be monitored via measurement means which can determine the concentration. However, the control can also be carried out by measuring or controlling the amount of sediment and the amount of water which are used to provide the sediment-water mixture.Fig. 1 further shows a control device which is designated 5. The control device 5 is connected to the device for supplying a sediment-water mixture 4 in such a way that it can control the amount of sediment contained in the supplied sediment-water mixture. In the known method, the quantity of sediment introduced into the connecting line 6 per time interval does not exceed a predefined maximum permissible quantity, wherein the respectively valid maximum permissible quantity of sediment introduced depends on the current operating mode of the hydroelectric power plant 2. This can achieve the effect that, on the one hand, erosion damage to the water power plant 2 is minimized and, on the other hand, as much sediment as possible can be discharged in a given period of time.FIG. 2 shows an arrangement which is suitable for carrying out the method according to the invention. With regard to the body of water 1, the hydroelectric power plant 2, the device for providing a sediment-water mixture 4, the connecting line 6 and the surface water 7, the explanations given above with respect to FIG. 1 apply. The discharge element 3 and the control device 5 play no role or only a very minor role for the method according to the invention.The method according to the invention is characterized in that at least one additional water engine is provided and installed before the actual sediment transfer, and during the subsequent sediment transfer, that sediment-water mixture which passes a water engine during the transfer passes exclusively the additional water engine. The method according to the invention thus comprises the following steps in the sequence indicated:providing and installing a further additional water engine (8);receiving sediment from the surface water (7);transferring sediment to the device (4) for providing a sediment-water mixture;providing a sediment-water mixture;transferring the provided sediment-water mixture into the underwater, wherein at least a portion of the provided sediment-water mixture passes a water engine;wherein the sediment-water mixture transferred into the subsea exclusively passes the further additional water engine 8 provided it passes a water engine.The following steps can form a single process (for example if the device for providing a sediment-water mixture 4 is designed as a vacuum excavator):receiving sediment from the surface water (7);transferring sediment to the device (4) for providing a sediment-water mixture;providing a sediment-water mixture;In FIG. 2, the additionally installed water engine is indicated by the square with the circle drawn in, which is denoted by 8. The device for supplying a sediment-water mixture 4 is connected to the additional water engine 8 by a transport line, which is designated 9. The additional water engine 8 is connected to the subsea via an outlet, which is designated 10. The outlet 10 of the additional water engine 8 can open into the outlet of the water power plant as shown in FIG. 2. The additional water engine 8 can be arranged in the vicinity of the power house of the water power plant or else in the same (see FIG. 3 ). To maximize the electrical energy produced by the additional water engine 8, it is advantageous if the additional water engine is arranged as low as possible.The inventor has recognized that several advantages can be achieved by installing an additional water engine 8, by means of which the transfer of the sediment-water mixture takes place (if the same takes place by means of a water engine). On the one hand, the additional water engine 8 can be designed to be particularly robust, so that severe damage, which can be caused by the passage of the sediment-water mixture through the water engine 8, is not to be feared even over a relatively long period of time. In addition, the additional water engine 8 can be adapted to the device for supplying a sediment-water mixture 4 in such a way that the additional water engine operates in an optimum manner when the device for supplying a sediment-water mixture 4 delivers an optimum sediment-water mixture, i.e. the capacity of the additional water power plant is approximately equal to the optimum delivery rate of the device for supplying a sediment-water mixture 4. In addition, the control process which was described above in connection with the control device 5 from FIG. 1 can be omitted. As a result, the method according to the invention is much simpler to carry out than the known method.FIG. 3 shows a further arrangement viewed from above, which is suitable for carrying out the method according to the invention. The terms correspond to the terms of the preceding figures. On the left side, the surface water 7 is located, on the right side, the surface water. The hydroelectric power plant 2 is arranged therebetween, which comprises a power house. The water engines are located in the power house. The three lower water engines are the water engines permanently installed in the water power plant 2. The uppermost water engine, again designated 8, is the additionally installed water engine. It is arranged in the power house of the water power plant 2 in an originally unused propulsion water path, as is present in some water power plants. The transport line 9 opens into this driving water path. Unlike in the arrangement shown in FIG. 2, in the arrangement according to FIG. 3, in addition to the sediment-water mixture provided by the device for providing a sediment-water mixture 4, water also passes directly from the surface 7 into the additional water engine 8.After completion of the sediment transfer, the additionally installed water engine 8 can be uninstalled again. If sediment transfers are carried out periodically planned on the body of water of a water power plant, then it may be advantageous under certain circumstances if the additionally installed water engine 8 remains permanently installed. Then, of course, the subsequent sediment transfers also fall under the process according to the invention.It should be mentioned that it may be advantageous if not all the sediment removed from the surface water 7 passes through the additionally installed water engine 8. Thus, when the sediment-water mixture is provided, larger sediment constituents such as, for example, coarse oil can advantageously be screened out of the absorbed sediment and transferred or deposited separately. That is to say, a portion of the sediment removed from the surface water cannot pass into the surface water at all or into the surface water in a different path than through the additionally installed water engine 8. According to the invention, however, the relevant sediment then also does not pass through another water engine of the water power plant 2. Since the sieved-out sediment is usually not provided as a sediment-water mixture, it applies in this case that the complete provided sediment-water mixture passes through the additionally installed water engine 8.In the case of larger surface waters, more than one device for providing a sediment-water mixture can be used. In this case, a single additional water engine can receive the sediment-water mixture provided by all devices for providing a sediment-water mixture, or more than one additionally installed water engine can be provided for this purpose, e.g. one additionally installed water engine for each device for providing a sediment-water mixture.List of reference characters1 Water body 2 Water power plant 3 Discharge element 4 Device for providing a sediment-water mixture 5 Control device 6 Connecting line 7 Surface water 8 Additionally installed water engine 9 Transport line 10 Outlet

Claims

Method for transferring sediment in a body of water (1), wherein the body of water (1) comprises an upper water (7) and an underwater, and wherein a water power plant (2) with at least one water engine is arranged between the upper water (7) and the underwater, and wherein at least one device for providing a sediment-water mixture (4) is provided, and wherein the method comprises the following steps: - receiving sediment from the upper water (7); - transferring sediment to the at least one device for providing a sediment-water mixture (4); - providing sediment-water mixture; transferring the provided sediment-water mixture into the underwater, wherein at least a part of the provided sediment-water mixture passes a water engine (8); characterized in that before the absorption of sediment from the surface is started, at least one further additional water engine (8) is provided and installed, and wherein the provided sediment-water mixture, in order to get into the underwater, exclusively passes the at least one further additional water engine (8), provided it passes a water engine.Method according to claim 1, wherein the hydroelectric power plant (2) comprises a power house, and wherein the at least one further additional water engine (8) is arranged outside the power house.Method according to claim 1, wherein the hydroelectric power plant (2) comprises a power house, and wherein the at least one further additional water engine (8) is arranged inside the power house.Method according to one of the preceding claims, wherein the further additional water engine (8) is designed such that the capacity of the at least one further additional water engine (8) to swallow is at least as great as an optimum delivery rate of the at least one device for providing a sediment-water mixture (4).

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