Structure and method for improving efficiency of water turbine through pressure pump and lifting efficiency calculation method

Abstract

The invention relates to a structure and method for improving the efficiency of a water turbine through a pressure pump and a lifting efficiency calculation method, and belongs to the technical field of water conservancy projects. The structure mainly comprises a forebay, a pressure pump, a water pump room, a check valve and the like. A forebay is built on one side of a water inlet of the hydropower station and used for storing water. A water pump room is arranged at the middle lower part of the forebay side wall; a pressure pump is mounted in the water pump room; a check valve is arranged at the water inlet of the forebay to prevent water in the forebay from flowing back into the reservoir. When the water level of the reservoir is low, water in the reservoir is pumped into the forebay through the pressure pump, and the water level of the forebay is increased; when the water level in the reservoir is higher than that of the forebay, the check valve is automatically opened under the action of reservoir water pressure, water in the reservoir automatically flows into the forebay, and energy is saved. The method is simple and convenient, the structure is simple, and when the water level of the reservoir is low, the running water head of the water turbine is conveniently increased, the running efficiency of the water turbine is improved, the water consumption is reduced, and the generating capacity of a hydropower station is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy engineering, and specifically relates to a structure and method for improving the efficiency of a water turbine by utilizing a pressure pump, and a method for calculating the improved efficiency. Background Art

[0002] At present, through optimized design, regular maintenance and improved operation management, the efficiency of turbines can be significantly improved, and the overall power generation capacity and economic benefits of hydropower stations can be improved. However, each turbine design has a specific rated head and flow range. Only within this range, the efficiency of the turbine is usually high, and the efficiency of some large and medium-sized turbines can reach more than 95%. However, if the working head of the turbine is far away from the rated head and flow, the efficiency of the turbine will be greatly reduced, even to only about 30%. Even for new turbines, under rated head, when the turbine output is only 50% of the rated power, its efficiency will be reduced to about 80%; if the head is lower than the rated head, its efficiency will continue to decline. Therefore, the working head and actual output of the turbine will affect the efficiency of the turbine. At the same time, as the use time goes by, the turbine will also face aging problems, which will continuously reduce its efficiency and seriously affect the power generation capacity of the hydropower station. At present, the design level of water turbines is already very high, and the efficiency of water turbines can be guaranteed to be above 90%. It is difficult to significantly improve the efficiency of water turbines by relying on optimized design and regular maintenance of water turbines. Therefore, some new methods and means are urgently needed to improve the efficiency of water turbines.

[0003] One of the reasons for the low operating efficiency of the turbine is that the low water level in the reservoir leads to a small working head of the turbine. In the middle and late stages of the dry season, and in the flood season, the water level in front of the reservoir is relatively low for flood control purposes, which will lead to a low working head of the turbine. In addition, the low operating efficiency of the turbine will also lead to large vibration of the unit, worsening the operating conditions of the turbine, further reducing the efficiency of the turbine, and also affecting the safety of the pier. Summary of the invention

[0004] In view of the problem that the efficiency of existing turbines will be greatly reduced when the working water head is far lower than the rated water head, the present invention proposes a structure, method and efficiency calculation method for improving the efficiency of turbines by using a pressure pump, and a forebay is built on one side of the water inlet of the hydropower station for water storage. When the water level of the reservoir is low, a pressure pump can be used to draw water from the reservoir and inject it into the forebay to raise the water level of the forebay and ensure that the water level of the forebay is at a high water level, thereby increasing the working water head of the turbine and improving the efficiency of the turbine. At the same time, when the turbine is working efficiently, it runs smoothly and can also reduce the vibration of the turbine unit, which is beneficial to the safety of the hydropower station plant.

[0005] The technical solution adopted by the present invention is: a structure for improving the efficiency of a water turbine by using a pressure pump, comprising a forebay 1, a pressure pump 2, a pump house 3, a forebay water inlet 4, a forebay water outlet 5, a hydropower station water inlet 7, a water level sensor 8, a reverse water valve I 9, a reverse water valve II 10, and a control system 11;

[0006] The forebay 1 is built on the upstream side of the water inlet 7 of the hydropower station, and is surrounded by side walls, a bottom plate and a dam. The elevation of the bottom plate of the forebay 1 is lower than that of the water inlet 7 of the hydropower station. The pressure pump 2 is installed in the pump house 3 at the middle and lower part of the side wall of the forebay 1. The forebay water inlet 4 is arranged at the bottom of the side wall of the forebay 1. The reverse water valve I 9 and the reverse water valve II 10 are installed at the end of the forebay water inlet 4 at the bottom of the pump house 3, and the reverse water valve I 9 is located on the upstream side of the water inlet of the pressure chamber of the pressure pump 2, and the reverse water valve II 10 is arranged on the downstream side of the water inlet of the pressure chamber of the pressure pump 2. The forebay drain port 5 is arranged at the top of the side wall of the forebay 1, and the water level sensor 8 is arranged at the top of the side wall of the forebay 1 and extends into the forebay 1. The pressure pump 2 and the water level sensor 8 are both connected to the control system 11.

[0007] Preferably, a trash rack 6 is arranged at the front end of the forebay water inlet 4 close to the reservoir.

[0008] Preferably, the elevation of the top of the side wall of the forebay 1 is consistent with the elevation of the dam top.

[0009] Preferably, the elevation of the bottom plate of the forebay 1 is about 1.0 m lower than the elevation of the bottom plate of the water inlet 7 of the hydropower station.

[0010] Preferably, the volume of the forebay 1 is the amount of water required for the turbine to operate at rated flow for 60 to 90 seconds.

[0011] Preferably, the maximum water lifting capacity of the pressure pump 2 matches the rated flow of the turbine.

[0012] Preferably, the control system 11 is arranged in a central control room of the hydropower station.

[0013] A method for improving the efficiency of a water turbine by using a pressure pump, using the structure for improving the efficiency of a water turbine by using a pressure pump, and the specific steps are as follows:

[0014] Step 1: The water level sensor 8 senses the water level of the forebay 1 and transmits the detected water level information to the control system 11. The control system 11 calculates the working water head of the turbine according to the water level of the forebay 1 and the water level downstream of the hydropower station;

[0015] Step 2: If the water level in the reservoir is higher than the water level in the forebay 1, the working water head of the turbine is higher than the rated water head of the turbine, the control system 11 controls the pressure pump 2 not to work, the reverse water valve I9 ​​and the reverse water valve II 10 are directly opened under the water pressure in the reservoir, and the water in the reservoir directly flows into the forebay 1 through the reverse water valve I9 ​​and the reverse water valve II 10; if the water level in the reservoir is lower than the water level in the forebay 1, the working water head of the turbine is lower than the rated water head of the turbine, the reverse water valve I9 ​​and the reverse water valve II 10 are automatically closed under the action of the reverse water flow, and at this time the control system 11 connects the circuit of the pressure pump 2, and the pressure pump 2 starts to work;

[0016] Step 3: When the pressure pump 2 absorbs water, the pressure chamber of the pressure pump 2 generates negative pressure, the reverse water valve I 9 opens and the reverse water valve II 10 closes, and water enters the pressure chamber of the pressure pump 2 from the fore pool water inlet 4;

[0017] Step 4: When the pressure pump 2 discharges water, the reverse water valve I 9 is closed and the reverse water valve II 10 is opened under the water pressure in the pressure chamber, and water is discharged from the pressure chamber of the pressure pump 2 into the front pool 1, so that water is pumped from the reservoir to the front pool 1;

[0018] Step 5: As the water level of the forebay 1 continues to increase, when the control system 11 calculates that the working water head of the turbine has reached the rated water head, the control system 11 controls the pressure pump 2 to stop working.

[0019] A method for calculating the efficiency of a hydraulic turbine using a pressure pump, comprising the following steps:

[0020] Assuming that the area of ​​the turbine inlet and the pressure pump 2 inlet are both A, then

[0021] The output p1 of the turbine before the water level rises is

[0022]

[0023] In the formula: η1——efficiency of the turbine before the water level is raised; γ——weight of water; μ——discharge coefficient of the water inlet orifice; h1——working water head of the turbine before the water level is raised;

[0024] After the water level is raised, the turbine output p2 is

[0025]

[0026] Where: η2——efficiency of the turbine after the water level is raised; h2——working water head of the turbine after the water level is raised;

[0027] Since the pressure pump 2 consumes electrical energy to pump water, the power consumption p3 is

[0028]

[0029] Where: η3——efficiency of the pressure pump; Δh——lifting head of the pressure pump;

[0030] The lifting head Δh of pressure pump 2 is

[0031] Δh=h2-h1(4)

[0032] Then the actual output of the turbine after the water level rises is

[0033]

[0034]

[0035] From formula (6), we can get the turbine efficiency. With the increase of h2 / h1, η2 / η1 will also increase, and p2' / p1 will increase, so the efficiency of the turbine will continue to improve.

[0036] The beneficial effects of the present invention are:

[0037] (1) When the water level in the reservoir is low, the working head of the turbine is low, resulting in low operating efficiency. By building a reservoir at the water inlet of the hydropower station, the water level at the water inlet of the hydropower station can be raised, the working head of the turbine can be increased, thereby improving the efficiency of the turbine and increasing the power generation of the hydropower station.

[0038] (2) It can reduce the impact of unfavorable working conditions on the turbine, keep it in the high-efficiency operating area for a long time, and improve the reliability and service life of the equipment.

[0039] (3) This method is simple and reliable, and is easier to implement than the optimization design of the turbine. It also does not require the replacement of the original turbine unit, thereby improving the utilization rate of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a typical cross-sectional schematic diagram of the present invention;

[0041] Figure 2 It is a typical plan view of the present invention;

[0042] Figure 3 It is a schematic diagram of the upstream elevation of the present invention;

[0043] Figure 4 It is a schematic diagram of the control system of the present invention.

[0044] The numbers in the figure are: forebay-1, pressure pump-2, pump house-3, forebay water inlet-4, forebay drain outlet-5, trash rack-6, hydropower station water inlet-7, water level sensor-8, backflow valve I-9, backflow valve II-10, control system-11. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the content of the present invention is not limited to the scope of the embodiments.

[0046] Embodiment 1: A structure for improving the efficiency of a water turbine by using a pressure pump, comprising a forebay 1, a pressure pump 2, a pump house 3, a forebay water inlet 4, a forebay water outlet 5, a hydropower station water inlet 7, a water level sensor 8, a reverse water valve I 9, a reverse water valve II 10, and a control system 11;

[0047] The forebay 1 is built on the upstream side of the water inlet 7 of the hydropower station, and is surrounded by side walls, a bottom plate and a dam. The elevation of the bottom plate of the forebay 1 is lower than that of the water inlet 7 of the hydropower station. The pressure pump 2 is installed in the pump house 3 at the middle and lower part of the side wall of the forebay 1. The forebay water inlet 4 is arranged at the bottom of the side wall of the forebay 1. The reverse water valve I 9 and the reverse water valve II 10 are installed at the end of the forebay water inlet 4 at the bottom of the pump house 3. Specifically, the reverse water valve I 9 is located on the upstream side of the water inlet of the pressure chamber of the pressure pump 2, and the reverse water valve II 10 is arranged on the downstream side of the water inlet of the pressure chamber of the pressure pump 2. The forebay drain port 5 is arranged at the top of the side wall of the forebay 1 for draining excess water in the forebay 1. The water level sensor 8 is arranged at the top of the side wall of the forebay 1 and extends into the forebay about 0.5m by a bracket for measuring the water level of the forebay 1 at all times. The pressure pump 2 and the water level sensor 8 are both connected to the control system 11.

[0048] The forebay 1 is built on the upstream side of the water inlet 7 of the hydropower station and is used to store water to increase the working water head of the turbine. When the water level of the reservoir is low, the pressure pump 2 is used to pump water from the reservoir into the forebay 1 to raise the water level of the forebay 1 to increase the working water head of the turbine, thereby improving the efficiency of the turbine. The operation of the pressure pump 2 is automatically controlled by the control system 11 to ensure that the turbine operates within the rated water head range. Excess water in the forebay 1 can be discharged into the reservoir through the forebay drain port 5. The reverse valve I9 ​​and the reverse valve II 10 have a one-way conduction function to prevent the water in the forebay 1 from flowing back into the reservoir. In addition, when the forebay 1 needs to be desilted, the reverse valve I 9 and the reverse valve II 10 can also be manually opened to use a sludge pump for desilting.

[0049] Furthermore, a trash rack 6 is arranged at the front end of the forebay water inlet 4, close to the reservoir side, to prevent large floating objects from entering and affecting the operation of the pressure pump 2, the backflow valve I 9 and the backflow valve II 10.

[0050] Furthermore, the elevation of the top of the side wall of the forebay 1 is consistent with the elevation of the dam top.

[0051] Furthermore, the elevation of the bottom plate of the forebay 1 is about 1.0m lower than the elevation of the bottom plate of the water inlet 7 of the hydropower station.

[0052] Furthermore, the volume of the forebay 1 is the amount of water required for the turbine to operate at rated flow for 60 to 90 seconds.

[0053] Furthermore, the maximum water lifting capacity of the pressure pump 2 matches the rated flow of the turbine.

[0054] Furthermore, the control system 11 is arranged in the central control room of the hydropower station.

[0055] A method for improving the efficiency of a water turbine by using a pressure pump, using the structure for improving the efficiency of a water turbine by using a pressure pump, and the specific steps are as follows:

[0056] Step 1: The water level sensor 8 senses the water level of the forebay 1 and transmits the detected water level information to the control system 11. The control system 11 calculates the working water head of the turbine according to the water level of the forebay 1 and the water level downstream of the hydropower station;

[0057] Step 2: If the water level in the reservoir is higher than the water level in the forebay 1, the working water head of the turbine is higher than the rated water head of the turbine, the control system 11 controls the pressure pump 2 not to work, and the reverse water valve I 9 and the reverse water valve II 10 are directly opened under the water pressure in the reservoir, and the water in the reservoir directly flows into the forebay 1 through the reverse water valve I 9 and the reverse water valve II 10 for power generation; if the water level in the reservoir is lower than the water level in the forebay 1, the working water head of the turbine is lower than the rated water head of the turbine, and the reverse water valve I 9 and the reverse water valve II 10 are automatically closed under the action of the reverse water flow to prevent the water in the forebay 1 from flowing back into the reservoir. At this time, the control system 11 connects the circuit of the pressure pump 2, and the pressure pump 2 starts to work;

[0058] Step 3: When the pressure pump 2 absorbs water, the pressure chamber of the pressure pump 2 generates negative pressure, the reverse water valve I 9 opens and the reverse water valve II 10 closes, and water enters the pressure chamber of the pressure pump 2 from the fore pool water inlet 4;

[0059] Step 4: When the pressure pump 2 discharges water, the reverse water valve I 9 is closed and the reverse water valve II 10 is opened under the water pressure in the pressure chamber, and water is discharged from the pressure chamber of the pressure pump 2 into the front pool 1, so that water is pumped from the reservoir to the front pool 1;

[0060] Step 5: As the water level of the forebay 1 continues to increase, when the control system 11 calculates that the working water head of the turbine has reached the rated water head, the control system 11 controls the pressure pump 2 to stop working.

[0061] A method for calculating the efficiency of a hydraulic turbine using a pressure pump, comprising the following steps:

[0062] Assuming that the area of ​​the turbine inlet and the pressure pump 2 inlet are both A, then

[0063] The output p1 of the turbine before the water level rises is

[0064]

[0065] In the formula: η1——efficiency of the turbine before the water level is raised; γ——weight of water; μ——discharge coefficient of the water inlet orifice; h1——working water head of the turbine before the water level is raised;

[0066] After the water level is raised, the turbine output p2 is

[0067]

[0068] Where: η2——efficiency of the turbine after the water level is raised; h2——working water head of the turbine after the water level is raised;

[0069] Since the pressure pump 2 consumes electrical energy to pump water, the power consumption p3 is

[0070]

[0071] Where: η3——efficiency of the pressure pump; Δh——lifting head of the pressure pump;

[0072] The lifting head Δh of pressure pump 2 is

[0073] Δh=h2-h1(4)

[0074] Then the actual output of the turbine after the water level rises is

[0075]

[0076]

[0077] From formula (6), we can get the turbine efficiency. With the increase of h2 / h1, η2 / η1 will also increase, and p2' / p1 will increase, so the efficiency of the turbine will continue to improve.

[0078] If h2 / h1=2, η2 / η1=1.28, then p2' / p1=2.15, the actual output of the turbine will increase by 115%, which is a very obvious effect.

[0079] The present invention proposes a structure, method and efficiency calculation method for improving the efficiency of a water turbine by using a pressure pump, which can solve the problem that the water level in front of the reservoir is low during the flood season and the operating efficiency of the water turbine is low in most existing hydropower stations. When the water level in the reservoir is low, it is very convenient to increase the operating head of the water turbine, greatly improve the operating efficiency of the water turbine, reduce water consumption, increase the power generation of the hydropower station, and increase the economic benefits of the hydropower station. The method of the present invention is simple and the structure is simple.

[0080] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A structure for improving the efficiency of a water turbine by using a pressure pump, characterized in that: It includes a forebay (1), a pressure pump (2), a pump house (3), a forebay water inlet (4), a forebay water outlet (5), a hydropower station water inlet (7), a water level sensor (8), a reverse water valve I (9), a reverse water valve II (10), and a control system (11); The forebay (1) is constructed on the upstream side of the water inlet (7) of the hydropower station and is surrounded by side walls, a bottom plate and a dam. The elevation of the bottom plate of the forebay (1) is lower than that of the water inlet (7) of the hydropower station. The pressure pump (2) is installed in a pump house (3) at the middle and lower part of the side wall of the forebay (1). The forebay water inlet (4) is arranged at the bottom of the side wall of the forebay (1). The reverse water valve I (9) and the reverse water valve II (10) are installed at the end of the forebay water inlet (4) at the bottom of the pump house (3). The reverse water valve I (9) is located at the upstream side of the water inlet of the pressure chamber of the pressure pump (2). The reverse water valve II (10) is arranged at the downstream side of the water inlet of the pressure chamber of the pressure pump (2). The forebay drain port (5) is arranged at the top of the side wall of the forebay (1). The water level sensor (8) is arranged at the top of the side wall of the forebay (1) and extends into the forebay (1). The pressure pump (2) and the water level sensor (8) are both connected to a control system (11).

2. The structure for improving the efficiency of a water turbine by using a pressure pump according to claim 1, characterized in that: A trash rack (6) is arranged at the front end of the forebay water inlet (4) close to the reservoir.

3. The structure for improving the efficiency of a water turbine by using a pressure pump according to claim 1, characterized in that: The elevation of the top of the side wall of the fore pool (1) is consistent with the elevation of the top of the dam.

4. The structure for improving the efficiency of a water turbine by using a pressure pump according to claim 1, characterized in that: The elevation of the bottom plate of the forebay (1) is about 1.0 m lower than the elevation of the bottom plate of the water inlet (7) of the hydropower station.

5. The structure for improving the efficiency of a water turbine by using a pressure pump according to claim 1, characterized in that: The volume of the forebay (1) is the amount of water required for the turbine to operate at rated flow for 60 to 90 seconds.

6. The structure for improving the efficiency of a water turbine by using a pressure pump according to claim 1, characterized in that: The maximum water lifting capacity of the pressure pump (2) matches the rated flow rate of the water turbine.

7. The structure for improving the efficiency of a water turbine by using a pressure pump according to claim 1, characterized in that: The control system (11) is arranged in the central control room of the hydropower station.

8. A method for improving the efficiency of a water turbine using a pressure pump, characterized in that: The structure for improving the efficiency of a water turbine by using a pressure pump as described in any one of claims 1 to 7 is adopted, and the specific steps are as follows: Step 1: The water level sensor (8) senses the water level of the forebay (1) and transmits the detected water level information to the control system (11). The control system (11) calculates the working water head of the turbine according to the water level of the forebay (1) and the water level downstream of the hydropower station; Step 2: If the water level in the reservoir is higher than the water level in the forebay (1), the working water head of the turbine is higher than the rated water head of the turbine, the control system (11) controls the pressure pump (2) to stop working, the reverse valve I (9) and the reverse valve II (10) are directly opened under the water pressure in the reservoir, and the water in the reservoir directly flows into the forebay (1) through the reverse valve I (9) and the reverse valve II (10); if the water level in the reservoir is lower than the water level in the forebay (1), the working water head of the turbine is lower than the rated water head of the turbine, the reverse valve I (9) and the reverse valve II (10) are automatically closed under the action of the reverse water flow, and at this time the control system (11) connects the circuit of the pressure pump (2), and the pressure pump (2) starts to work; Step 3: When the pressure pump (2) absorbs water, negative pressure is generated in the pressure chamber of the pressure pump (2), the reverse water valve I (9) is opened and the reverse water valve II (10) is closed, and water enters the pressure chamber of the pressure pump (2) from the fore pool water inlet (4); Step 4: When the pressure pump (2) discharges water, the reverse valve I (9) is closed and the reverse valve II (10) is opened under the action of the water pressure in the pressure chamber, and water is discharged from the pressure chamber of the pressure pump (2) into the forebay (1), thereby pumping water from the reservoir into the forebay (1); Step 5: As the water level in the forebay (1) continues to increase, when the control system (11) calculates that the working water head of the turbine has reached the rated water head, the control system (11) controls the pressure pump (2) to stop working.

9. A method for calculating the efficiency of a hydraulic turbine using a pressure pump, characterized in that: The method for improving the efficiency of a water turbine by using a pressure pump as claimed in claim 8 comprises the following steps: Assuming that the area of ​​the turbine inlet and the pressure pump (2) inlet are both A, then The output p1 of the turbine before the water level rises is In the formula: η1——efficiency of the turbine before the water level is raised; γ——weight of water; μ——discharge coefficient of the water inlet orifice; h1——working water head of the turbine before the water level is raised; After the water level is raised, the turbine output p2 is Where: η2——efficiency of the turbine after the water level is raised; h2——working water head of the turbine after the water level is raised; Since the pressure pump (2) consumes electrical energy to pump water, the power consumption p3 is Where: η3——efficiency of the pressure pump; Δh——lifting head of the pressure pump; The lifting head Δh of the pressure pump (2) is Δh=h2-h1(4) Then the actual output of the turbine after the water level rises is From formula (6), we can get the turbine efficiency. With the increase of h2 / h1, η2 / η1 will also increase, and p2' / p1 will increase, so the efficiency of the turbine will continue to improve.

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