Water turbine top cover forced air supply test system

Abstract

The utility model relates to a forced air supply test system for a top cover of a water turbine. The forced air supply test system comprises an air compressor, an air storage tank, a first ball valve, a pneumatic control valve, a flowmeter, a second ball valve and a check valve, an air outlet of the air compressor is communicated with an inlet of the air storage tank, and an air outlet of the air storage tank, the first ball valve, the pneumatic control valve, the flow meter, the second ball valve and the check valve are sequentially communicated through pipelines. An outlet of the check valve is communicated with a reserved air supply pipeline which is communicated with an air inlet of the top cover of the water turbine; the pipelines at the inlet and the outlet of the flowmeter are straight pipes and have certain lengths. The air supply test system is simple in overall structure, forced air supply tests of the top cover with different air supply amounts under different loads can be completed through cooperation of the serially-connected components, and research data are provided for actual water turbine air supply.

Description

Technical Field

[0001] The utility model relates to the technical field of water turbine air supplementation test, in particular to a water turbine top cover forced air supplementation test system. Background Art

[0002] Hydropower is a highly efficient and clean renewable energy source with abundant reserves. It is the most mature and commercial development mode among the renewable resource power generation technologies today. Due to its flexible operation and rapid response, hydropower plays an irreplaceable and important role in the power grid. In recent years, with the increase in the proportion of intermittent renewable energy sources such as wind energy, solar photovoltaic, solar thermal, biomass energy, geothermal energy and other energy sources in the power grid, it has caused a great impact on the existing power grid parameters. Hydropower stations with peak load regulation and frequency regulation will deviate from the optimal operating conditions more frequently to adjust the power grid parameters. The turbine will inevitably experience dynamic load imbalance, thereby inducing complex flow separation and vortex phenomena, which seriously restricts its efficient and stable operation.

[0003] The research results show that when a Francis turbine is running under partial load conditions, two typical vortex phenomena will occur - the draft tube vortex belt and the blade cavitation vortex, accompanied by high-amplitude pressure pulsation, which will have a certain impact on the operation of the turbine unit. Further analysis shows that the unstable high-amplitude pressure pulsation is induced by the spatiotemporal evolution of the vortex structure. Therefore, in order to ensure the operating stability of the turbine under partial working conditions, certain measures can be taken to suppress the generation of vortex structure, thereby improving the hydraulic performance of the turbine and effectively expanding the stable operating range of the turbine. The essence of cavitation is that the local pressure is less than the local pressure and cavitation is formed. Therefore, the generation of cavitation can be suppressed by increasing the pressure in the draft tube and the runner. Injecting air into the turbine is an effective active flow control method to increase its internal pressure and thus suppress the occurrence of cavitation. In engineering, air is generally introduced into the center hole of the turbine main shaft or the air supply short pipe installed in the draft tube cone section to suppress the pressure pulsation caused by the draft tube vortex belt. However, this air supply measure only affects the downstream area of ​​the runner. In order to effectively suppress the unstable blade cavitation vortex structure in the runner, air must be introduced from the upstream of the runner, that is, through the top cover, the bladeless area between the movable guide vane and the runner to replenish air. The reasonable selection of the air replenishment volume is an important factor in suppressing the occurrence of cavitation in the turbine. Only when the air replenishment volume exceeds a critical value can the occurrence of cavitation be suppressed and the pressure pulsation induced by cavitation be effectively reduced. However, excessive air replenishment not only consumes more external energy, but also causes excessive interference to the mainstream in the turbine, which may reversely deteriorate the hydraulic performance of the turbine. Air replenishment through the top cover can change the pressure distribution in the flow field. The gas displacement of the liquid flow field reduces the ratio of its circumferential velocity component to the axial velocity component, and the cross-sectional axial velocity distribution tends to be uniform, effectively reducing the eccentricity of the vortex belt and suppressing pressure pulsation. At the same time, air replenishment also changes the pressure gradient distribution in the flow field. As air is introduced into the tailwater pipe, the pressure distribution in the tailwater pipe tends to be uniform, the adverse pressure gradient along the flow direction decreases, and the vortex belt shedding form caused by vortex separation is transformed into a columnar vortex belt. At the same time, the radial cross-sectional pressure gradient distribution also tends to be uniform, thereby suppressing the generation of pressure pulsation.

[0004] In recent years, most of the research on the improvement of stable performance of turbine units by air replenishment has been carried out through numerical simulation calculations and model tests, and there are few studies on the real machine test of forced air replenishment on the turbine top cover. Since there are obvious differences between the model and the real machine in terms of air replenishment volume and stable performance improvement effect, it is very necessary to carry out experimental research on forced air replenishment on the turbine top cover. Utility Model Content

[0005] The utility model provides a turbine top cover forced air supply test system, which has a simple overall structure and can complete top cover forced air supply tests with different air supply amounts under different loads through the cooperation of various series components, thereby providing research data for actual turbine air supply.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A turbine top cover forced air supply test system, comprising an air compressor, an air storage tank, a first ball valve, a pneumatic regulating valve, a flow meter, a second ball valve and a check valve;

[0008] The air outlet of the air compressor is connected to the inlet of the air storage tank, and the air outlet of the air storage tank, the first ball valve, the pneumatic regulating valve, the flow meter, the second ball valve and the check valve are connected in sequence through pipelines;

[0009] The outlet of the check valve is connected to a reserved air supply pipeline, and the reserved air supply pipeline is connected to the air inlet of the turbine top cover;

[0010] The pipes at the inlet and outlet of the above flow meter are straight pipes and have a certain length.

[0011] Preferably, the length of the pipeline at the inlet of the flow meter is greater than 3 times the inner diameter of the pipeline;

[0012] The length of the pipeline at the outlet of the above flow meter is greater than 1 times the inner diameter of the pipeline.

[0013] Preferably, it also includes a plurality of pipe clamps;

[0014] The pneumatic regulating valve, the flow meter, the ball valve and the pipeline at the inlet of the check valve are clamped on a fixed frame arranged in the power plant by the pipeline clamp.

[0015] Preferably, the pipeline between the first ball valve and the pneumatic regulating valve, the pipeline between the pneumatic regulating valve and the flow meter, the pipeline at the outlet of the flow meter, and the pipeline between the second ball valve and the check valve are all seamless steel pipes.

[0016] Preferably, the connecting pipe between the pipe at the outlet of the flow meter and the pipe at the inlet of the second ball valve is configured as a metal bellows.

[0017] Preferably, the metal bellows is clamped on a fixing frame provided in the power plant by the pipe clamps at intervals of 2000 mm.

[0018] Preferably, a gas-water separator is provided on the pipeline between the air inlet of the gas storage tank and the air outlet of the air compressor.

[0019] Preferably, the flow meter is a vortex flow meter.

[0020] Preferably, the pneumatic regulating valve is a programmable pneumatic regulating valve.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. The overall structural design is simple and reasonable. All components are connected in series. A pneumatic regulating valve is set to achieve precise adjustment of the air supply flow rate. The flow meter displays the accurate air supply flow rate in real time. It is safe and reliable. A check valve is set to prevent water in the runner chamber from flowing into the air supply system pipeline. The manual ball valve has low fluid resistance, simple structure, high reliability, easy operation, and rapid opening and closing. It can be closed at any time by rotating 90 degrees from fully open to fully closed, and the air supply to the unit can be stopped. Through the cooperation of various components, the top cover forced air supply test with different air supply volumes under different loads is completed.

[0023] 2. The pipes at the inlet and outlet of the flow meter are straight pipes and have a certain length, which ensures the accuracy of flow meter data collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a schematic diagram of the overall system of an embodiment of the present utility model.

[0026] Description of reference numerals:

[0027] 1. Air compressor; 2. Air storage tank; 3. First ball valve; 4. Pneumatic regulating valve; 5. Flow meter; 6. Second ball valve; 7. Check valve; 8. Reserved air supply pipeline; 9. Metal bellows; 10. Air-water separator; 11. Turbine top cover. DETAILED DESCRIPTION

[0028] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] like Figure 1 As shown, the embodiment of the utility model provides a turbine top cover forced air supply test system, including an air compressor 1, an air storage tank 2, a first ball valve 3, a pneumatic regulating valve 4, a flow meter 5, a second ball valve 6 and a check valve 7; wherein the air outlet of the air compressor 1 is connected to the inlet of the air storage tank 2 through a pipeline, and the air outlet of the air storage tank 2, the first ball valve 3, the pneumatic regulating valve 4, the flow meter 5, the second ball valve 6 and the check valve 7 are connected in sequence, and are connected in pairs through pipelines. Correspondingly, the outlet of the check valve 7 is connected to a reserved air supply pipeline 8, and the reserved air supply pipeline 8 is connected to the air inlet of the turbine top cover. Through the coordinated use of the air compressor 1, the air storage tank 2, the first ball valve 3, the pneumatic regulating valve 4, the flow meter 5, the second ball valve 6 and the check valve 7, the top cover forced air supply test with different air supply amounts under different loads is completed, and at the same time, the components are connected in series, and the overall structure is simple.

[0032] Specifically, after the test begins, the unit is operated to the test load condition point. After running under load for 10 minutes, the power plant system conducts stability data collection. After the data collection is completed, the first ball valve 3 and the second ball valve 6 in the top cover forced air supply test are adjusted to the normally open state, and then the air compressor 1 is operated to generate high-pressure gas, which is stored in the gas storage tank 2. As the opening of the pneumatic control valve 4 is adjusted, the high-pressure gas passes through the flow meter 5, the second ball valve 6 and the check valve 7 in turn, and finally continuously supplies the bladeless area in the turbine top cover through the air supply reserved pipeline 8. When the predetermined air supply volume of the test plan is reached, it runs for no less than 3 minutes, and then the power plant system conducts stability data collection after air supply, and then continues to adjust the opening of the pneumatic control valve 4, and continues to conduct stability data collection after air supply, so that the air supply volume reaches the predetermined maximum or minimum air supply volume, and so on, to complete the top cover forced air supply test with different air supply volumes under a certain load. After the full air supply test under a certain load is completed, adjust the opening of the pneumatic control valve 4 to make it completely closed, and no more high-pressure gas is added. When the air supply volume drops to 0m3 / s, the unit continues to operate stably for at least 10 minutes, then adjust the unit load to the next operating point, repeat the above test process, and complete the top cover forced air supply test under full load and full air supply volume. After the air supply test under the last load condition is completed, close the manual first ball valve 3 and the second ball valve 6, adjust the opening of the pneumatic control valve 4 to make it completely closed, and the air supply volume in the test system pipeline drops to 0m3 / s. The unit continues to operate stably for at least 10 minutes, then start the shutdown process, and the test is completed.

[0033] Specifically, in order to ensure the accuracy of data collection of the flow meter 5, the pipes at the inlet and outlet of the flow meter 5 are straight pipes and have a certain length, so that the gas can stably enter the flow meter 5 through the straight pipe, and then stably flow out through the straight pipe, to ensure the stability of the gas flow rate, to avoid the flow rate being different and causing inaccurate measurement of the flow meter 5, thereby causing inaccurate gas replenishment test data. Preferably, according to the inner diameter of the pipe, the length of the pipe at the inlet of the flow meter 5 is greater than 3 times the inner diameter of the pipe, and the length of the pipe at the outlet of the flow meter 5 is greater than 1 times the inner diameter of the pipe.

[0034] Preferably, in order to ensure the stability of the system during the gas supply test, the system also includes a plurality of pipe clamps, which are used to clamp the pipes, that is, the pipe clamps are used to clamp the pipes at the inlets of the pneumatic control valve 4, the flow meter 5, the ball valve and the check valve 7 on a fixed frame provided in the power plant, thereby fixing the components and restricting their displacement in the radial direction. Of course, short pipes do not need to be fixed, and long pipes need to be fixed again with pipe clamps. In short, the components and long pipes are fixed by pipe clamps to restrict their displacement in the radial direction, so that the gas flows stably, thereby ensuring the stability of the system in the gas supply test of the gas turbine top cover 11.

[0035] Preferably, the pipeline between the first ball valve 3 and the pneumatic regulating valve 4, the pipeline between the pneumatic regulating valve 4 and the flowmeter 5, the pipeline at the outlet of the flowmeter 5, and the pipeline between the second ball valve 6 and the check valve 7 are all seamless steel pipes, which have high pressure resistance, good toughness, light weight and good sealing.

[0036] Preferably, because the gas tank 2 is far away from the gas turbine, and in order to ensure the measurement stability of the flowmeter 5, the flowmeter 5 and the pneumatic regulating valve 4 need to be set close to the gas tank 2, so the flowmeter 5 is far away from the gas replenishment reserved pipeline 8, and the path is random, and the pipeline also needs to be flexibly arranged, so the connecting pipeline between the pipeline at the outlet of the flowmeter 5 and the pipeline at the inlet of the second ball valve 6 is set to a metal bellows 9, which ensures the connection strength while ensuring the flexibility of bending; and the pipeline at the inlet of the second ball valve 6 and the pipeline between the outlet of the second ball valve 6 and the check valve 7 are all straight pipes and are located near the gas turbine, and the middle metal bellows 9 is used for long-distance gas transportation to ensure the stability of the gas when the system is discharged.

[0037] Preferably, the metal bellows 9 is clamped on a fixed frame provided in the power plant by pipe clamps every 2000 mm to restrict its displacement in the radial direction and ensure the stability of the gas flow in the metal bellows 9 during the gas replenishment test.

[0038] Preferably, a gas-water separator 10 is provided on the pipeline between the air inlet of the gas storage tank 2 and the air outlet of the air compressor 1 to prevent the gas entering the gas storage tank 2 from containing water vapor or moisture, thereby ensuring the purity of the gas in the gas storage tank 2 and the accuracy of subsequent flow meter 5 measurements.

[0039] Preferably, the flowmeter 5 adopts a vortex flowmeter 5. The vortex flowmeter 5 is selected to detect the flow rate. It is not affected by the physical properties and density of the fluid and has good linearity in a wider flow range.

[0040] Preferably, the pneumatic regulating valve 4 adopts the existing programmable pneumatic regulating valve 4. The programmable pneumatic regulating valve 4 directly writes the control logic program into the valve group for regulation, which increases the convenience of use.

[0041] Preferably, each component in the system is connected to the pipeline through a flange to ensure the strength and sealing of the connection. When each component fails and needs to be replaced or repaired, it can be disassembled separately; and argon arc welding should be used for welding between the seamless steel pipe and the flange. After welding, the weld appearance and internal quality inspection should be carried out. There should be a smooth transition between welds and parent materials, welding slag and spatter should be cleaned up, the depth of incomplete penetration should be less than or equal to 1mm, and the cumulative length of incomplete penetration should not exceed 10% of the weld length.

[0042] Correspondingly, a check valve is provided on the pipeline between the gas-water separator 10 and the air compressor 1 to prevent water vapor from flowing back into the air compressor 1 .

[0043] The above-mentioned implementation modes are only preferred implementation modes of the present invention, and cannot be used to limit the protection scope of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A turbine top cover forced air supply test system, characterized in that: It includes an air compressor, an air storage tank, a first ball valve, a pneumatic regulating valve, a flow meter, a second ball valve and a check valve; The air outlet of the air compressor is connected to the inlet of the air storage tank, and the air outlet of the air storage tank, the first ball valve, the pneumatic regulating valve, the flow meter, the second ball valve and the check valve are connected in sequence through pipelines; The check valve outlet is connected to a reserved air supply pipeline, and the reserved air supply pipeline is connected to the air inlet of the turbine top cover; The pipes at the inlet and outlet of the flow meter are both straight pipes and have a certain length.

2. The turbine top cover forced air supply test system according to claim 1 is characterized in that: The length of the pipeline at the inlet of the flow meter is greater than 3 times the inner diameter of the pipeline; The length of the pipeline at the outlet of the flow meter is greater than 1 times the inner diameter of the pipeline.

3. The turbine top cover forced air supply test system according to claim 1, characterized in that: Also included are multiple pipe clamps; The pneumatic regulating valve, the flow meter, the ball valve and the pipeline at the inlet of the check valve are clamped on a fixing frame arranged in the power plant by the pipeline clamp.

4. The turbine top cover forced air supply test system according to claim 3 is characterized in that: The pipeline between the first ball valve and the pneumatic regulating valve, the pipeline between the pneumatic regulating valve and the flow meter, the pipeline at the outlet of the flow meter, and the pipeline between the second ball valve and the check valve are all seamless steel pipes.

5. The turbine top cover forced air supply test system according to claim 4, characterized in that: The communicating pipe between the pipe at the outlet of the flow meter and the pipe at the inlet of the second ball valve is set as a metal bellows.

6. The turbine top cover forced air supply test system according to claim 5, characterized in that: The metal corrugated pipe is clamped on a fixing frame arranged in the power plant by the pipe clamp every 2000 mm.

7. The turbine top cover forced air supply test system according to claim 1, characterized in that: An air-water separator is arranged on the pipeline between the air inlet of the air storage tank and the air outlet of the air compressor.

8. The turbine top cover forced air supply test system according to claim 1, characterized in that: The flow meter adopts a vortex flow meter.

9. The turbine top cover forced air supply test system according to claim 1, characterized in that: The pneumatic regulating valve is a programmable pneumatic regulating valve.

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