Experimental device and method suitable for water erosion of different low-pressure last-three-stage blades of steam turbine

Abstract

The invention discloses an experimental device and method suitable for water erosion of different low-pressure last-three-stage blades of a steam turbine. The experimental device comprises a steam generator, a ball valve a, a pressure reducing valve, a vortex shedding flowmeter, a nozzle, a cylinder body, a supporting flat plate, a blade shade, an exhaust port, a vacuum valve, a sucking pump, a computer, an air compressor, a particle generator, a ball valve b, a penultimate-stage stationary blade, a penultimate-stage movable blade, a penultimate-stage stationary blade, a penultimate-stage movable blade, a final-stage stationary blade, a final-stage movable blade and a sliding rod. According to the method, water erosion damage to different blades can be studied, different pressures in a cylinder body are controlled and changed through a sucking pump and a computer end, so that pressure values in the last three stages under different working conditions are achieved, nozzles are arranged along the blade heights, the flowing state of steam in a last three-stage blade channel is better simulated, the last three-stage blade is fixed to a sliding rod, and the working efficiency is improved. And the mutual influence between the blades is considered. And the blade shades with different sizes can construct last three-stage flow field structures for different blades.

Description

Technical Field

[0001] The invention belongs to the technical field of steam turbines in thermal power plants, and relates to a steam turbine blade water erosion test device and method, and specifically relates to an experimental device and method suitable for water erosion of different blades at the last three low-pressure stages of a steam turbine. Background Art

[0002] At present, in order to absorb new energy, deep peak regulation is common in most steam turbines, which need to operate under different loads. Under different loads, especially under low load, the working environment of the low-pressure last three-stage blades of the steam turbine is relatively harsh. The last three-stage blades of the steam turbine are prone to water erosion, and small pits and pitting appear on the surface of the last three-stage blades. In the long run, it may even cause the blades to break, seriously threatening the safe and stable operation of the steam turbine. Therefore, in order to study the water erosion mechanism of the last three stages of different blades of the steam turbine, an experimental device and method suitable for water erosion of different blades of the last three stages of the low-pressure steam turbine are designed to provide a theoretical basis for the safe operation and protection of the last stage blades of the steam turbine.

[0003] CN100575917C discloses a water erosion test device for steam turbine blades, which uses the collision between high-speed rotating blades and water droplets to simulate the blade erosion caused by the high-speed impact of water droplets on the blades in the low-pressure cylinder of the steam turbine; CN201653838U discloses a water erosion test device, which simulates the water erosion suffered by the last-stage blades of the steam turbine by the collision of high-pressure pulsed water jets with test pieces; CN102252927B discloses a high-pressure water jet rotating impact water erosion test device, which simulates the erosion of blades by water droplets in the steam turbine by the collision between high-speed jets and rotating test pieces; CN113267416B discloses a dynamic water erosion test device for steam turbine blades in a nuclear power plant, which can realize accelerated testing of the water erosion process of nuclear power steam turbine blades.

[0004] In summary, the existing turbine low-pressure blade erosion test device does not involve the last three blades, and cannot consider the mutual influence between the last three blades. Moreover, only blade samples of different sizes and models can be installed in the experimental device, and real blades of multiple sizes and models cannot be used for experiments, and the real flow of steam entering the flow channel and the flow field structure of real steam cannot be considered. Summary of the invention

[0005] In order to analyze the water erosion mechanism of different blades, the present invention provides an experimental device and method suitable for water erosion of different blades in the last three low-pressure stages of a steam turbine, providing a theoretical basis for the safety of multi-channel blades in the last three low-pressure cylinders of thermal power steam turbines under different working conditions.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] An experimental device suitable for water erosion of different blades of the last three low-pressure stages of a steam turbine comprises a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a cylinder body, a supporting plate, a blade cover, an exhaust port, a vacuum valve, an air pump, a computer, an air compressor, a particle generator, a ball valve b, a sub-sub ...

[0008] The steam generator is connected to one end of the ball valve a through the main steam pipeline, the other end of the ball valve a is connected to one end of the pressure reducing valve through the main steam pipeline, and the other end of the pressure reducing valve is connected to the vortex flowmeter through the main steam pipeline;

[0009] The air compressor is connected to the particle reactor through a branch pipeline, the particle reactor is connected to one end of the ball valve b through the branch pipeline, and the other end of the ball valve b is connected to the main steam pipeline through the branch pipeline. The air compressor brings water droplets of different diameters in the particle reactor into the main steam pipeline through the branch pipeline, and moves together with the superheated steam generated by the steam generator;

[0010] The nozzle is placed at the end of the main steam pipe and the front end of the second-last stator blade, and sprays the steam with water droplets toward the blade channel through the outlet;

[0011] A support plate is provided in the cylinder body, a slide bar is provided on the support plate, and the second-last-stage stationary blade, the second-last-stage moving blade, the second-last-stage stationary blade, the second-last-stage moving blade, the last-stage stationary blade, and the last-stage moving blade are fixed on the slide bar in sequence to form the last three-stage blades of the low-pressure cylinder of the steam turbine, and the blade cover is placed on the last three-stage blades of the low-pressure cylinder of the steam turbine to form the last three-stage multi-flow channel structure of the low-pressure cylinder of the steam turbine;

[0012] The cylinder body is provided with an exhaust port, and the exhaust port collects condensed water in the cylinder body;

[0013] One end of the vacuum valve is connected to the cylinder body through a pipeline, and the other end of the vacuum valve is connected to the air pump through a pipeline. The air pump performs air extraction on the cylinder body under the control of the vacuum valve;

[0014] The ball valve a and the pressure reducing valve are connected to a computer and are used to control the steam flow and steam pressure in the main steam pipeline;

[0015] The vortex flowmeter is connected to a computer and is used for controlling, monitoring and collecting flow data.

[0016] An experimental method suitable for water erosion of different blades of the last three low-pressure stages of a steam turbine comprises the following steps:

[0017] Step 1: Connect the above experimental devices in sequence, and fix the second-last-stage stationary blades, the second-last-stage moving blades, the second-last-stage stationary blades, the second-last-stage moving blades, the last-stage stationary blades and the last-stage moving blades on the sliding rod.

[0018] Step 2: The sliding rod is connected to the third-stage blades at the end of the low-pressure cylinder of the turbine, and the distance between the blades is changed by the sliding rod;

[0019] Step 3: The blade covers are arranged on the last three-stage blades of the low-pressure cylinder of the steam turbine to form a last three-stage multi-flow channel structure of the low-pressure cylinder of the steam turbine;

[0020] Step 4: Open the vacuum valve, turn on the vacuum pump, and set the pressure in the cylinder to the pressure in the last three stages of the steam turbine under rated load. The pressure value is controlled by the computer display. Then, according to the actual working pressure of the last three stages of the steam turbine, the pressure value in the device is set in sequence using the computer;

[0021] Step 5: The steam generated by the steam generator and the water droplets generated by the particle generator are mixed and sprayed out through a nozzle into the multi-flow passages of the last three-stage blades of the steam turbine;

[0022] Step 6: After the experiment is over, remove the third-stage blades at the end of the low-pressure cylinder of the turbine.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. Using the impact effect of water droplets on three-stage full-size real blades, the water erosion damage mechanism of different blades at the last three stages of low-pressure multi-channel steam turbine is studied.

[0025] 2. Blade masks of different sizes can construct different last three-stage flow field structures for different blades, and by replacing different blade masks, the water erosion of different blades in the last three stages of the turbine can be studied.

[0026] 3. By using the sliding rod connected to the blades, the distance between the blades can be changed, and the effect of different blade distances on turbine water erosion can be analyzed.

[0027] 4. Setting nozzles of different diameters along the blade height can more accurately simulate the flow state of steam and water droplets in the multi-flow channels of the last three stages of blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is an experimental framework diagram suitable for water erosion of different blades in the last three low-pressure stages of a steam turbine.

[0029] Figure 2 This is a partial enlarged view of the cylinder body.

[0030] Figure 3 This is a diagram of the nozzle group setup.

[0031] Figure 4 It is a flow chart of the experimental method.

[0032] In the figure: 1-steam generator, 2-ball valve a, 3-pressure reducing valve, 4-vortex flowmeter, 5-nozzle, 6-nozzle hole, 7-cylinder body, 8-support plate, 9-blade cover, 10-exhaust port, 11-vacuum valve, 12-air pump, 13-computer, 14-air compressor, 15-particle generator, 16-ball valve b, 17-sub-last stage static blade, 18-sub-last stage moving blade, 19-sub-last stage static blade, 20-sub-last stage moving blade, 21-last stage static blade, 22-last stage moving blade, 23-sliding rod. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0034] The present invention provides an experimental device suitable for water erosion of different blades at the last three stages of low-pressure turbines, such as Figure 1 As shown, the experimental device includes a steam generator 1, a ball valve a2, a pressure reducing valve 3, a vortex flowmeter 4, a nozzle 5, a nozzle hole 6, a cylinder 7, a supporting plate 8, a blade cover 9, an exhaust port 10, a vacuum valve 11, an air pump 12, a computer 13, an air compressor 14, a particle generator 15, a ball valve b16, a sub-last stage stationary blade 17, a sub-last stage moving blade 18, a sub-last stage stationary blade 19, a sub-last stage moving blade 20, a final stage stationary blade 21, a final stage moving blade 22, and a sliding rod 23, wherein:

[0035] The steam generator 1 is connected to one end of the ball valve a2 through the main steam pipeline, and the temperature and pressure of the outlet steam of the steam generator 1 can be set by itself;

[0036] The pressure reducing valve 3 is connected to the other end of the ball valve a2 through the main steam pipeline, and the pressure reducing valve 3 can adjust the steam pressure in the main steam pipeline;

[0037] The vortex flowmeter 4 is connected to the pressure reducing valve 3 through the main steam pipeline, and the vortex flowmeter 4 can measure the steam flow in the main steam pipeline;

[0038] The air compressor 14 is connected to the particle reactor 15 through a branch pipe, the particle reactor 15 is connected to one end of the ball valve b16 through the branch pipe, and the other end of the ball valve b16 is connected to the main steam pipe through the branch pipe. The air compressor 14 brings water droplets of different diameters in the particle reactor 15 into the main steam pipe through the branch pipe, and moves together with the superheated steam generated by the steam generator 1;

[0039] The nozzle 5 is placed at the end of the main steam pipe and the front end of the second-last stator blade 17, and sprays the steam with water droplets toward the blade channel through the outlet;

[0040] A support plate 8 is provided in the cylinder body 7, and a slide bar 23 is fixed on the support plate 8. The sub-last-stage stationary blades 17, the sub-last-stage moving blades 18, the sub-last-stage stationary blades 19, the sub-last-stage moving blades 20, the final-stage stationary blades 21, and the final-stage moving blades 22 are fixed on the slide bar 23 in sequence and can slide to form the final three-stage blades of the low-pressure cylinder of the steam turbine. At the same time, the final three-stage blades of different steam turbines can be replaced for testing, wherein the total number of slide bars 23 is N, and the sub-last-stage stationary blades, the sub-last-stage moving blades, the sub-last-stage stationary blades, the sub-last-stage moving blades, the final-stage stationary blades, and the final-stage moving blades are N each, and the total number of blades is 6N. These blades are fixed on the corresponding slide bars 23 to form a multi-flow channel structure of the final three stages of the low-pressure cylinder of the steam turbine, and the number of blades can be increased or decreased according to the number of flow channels;

[0041] The blade mask 9 is placed on the last three blades of the low-pressure cylinder of the steam turbine to better form the last three flow field structure. At the same time, different mask sizes can be replaced according to the sizes of different blades.

[0042] The slide bar 23 is connected to the third-stage blades at the end of the low-pressure cylinder of the steam turbine, and can change the distance between the blades;

[0043] Each of the sub-last-stage stationary blades 17 is provided with a row of nozzles of different sizes along the blade height to truly simulate the flow of steam along the blade height, and the number of rows of nozzles is determined according to the number of flow channels;

[0044] The vacuum pump 12, under the control of the vacuum valve 11, can perform vacuum processing on the cylinder 7, so that the pressure value in the cylinder 7 is first set to the pressure under the rated load, and the actual pressure in the low-pressure last three stages of the steam turbine under different loads is achieved by changing the different pressure values ​​in the cylinder 7. The size of the pressure value can be displayed by the computer 13;

[0045] The exhaust port 10 can collect condensed water in the cylinder 7;

[0046] The ball valve a2 and the pressure reducing valve 3 are connected to the computer 13 to control the steam flow and steam pressure in the main steam pipeline;

[0047] The vortex flowmeter 4 is connected to the computer 13 to realize the control, monitoring and collection of flow data.

[0048] The present invention also provides an experimental method suitable for water erosion of different blades in the last three stages of a low-pressure steam turbine. The method can be used to study water erosion damage to different blades. Through the control of a vacuum pump and a computer, different pressures in the cylinder can be changed to achieve pressure values ​​in the last three stages under different working conditions. Nozzles are set along the blade height to better simulate the flow state of steam in the last three stages of blade channels. The last three stages of blades are fixed on a sliding rod, and the distance between blades can be adjusted, taking into account the mutual influence between blades. The blade mask can be selected according to the size of the blade to be studied. The blade mask is to construct the flow field structure of the last three stages. Figure 1 As shown, the specific steps include:

[0049] Step 1: Connect the experimental device in sequence, and fix N sub-final-stage static blades, N sub-final-stage moving blades, N sub-final-stage static blades, N sub-final-stage moving blades, N final-stage static blades, and N final-stage moving blades on N sliding rods according to the example in the figure, N≧3;

[0050] Step 2: Open the vacuum valve, turn on the vacuum pump, and set the pressure in the cylinder to the pressure value in the last three stages under the rated load of the steam turbine for the first time. For the setting of the working pressure in the last three stages of the steam turbine under different loads, the pressure value is controlled by the computer;

[0051] Step 3: The high-temperature, high-pressure and high-speed steam generated by the steam generator is mixed with the water droplets generated by the particle generator and enters the multi-flow passages of the last three-stage blades of the steam turbine through the nozzle on the nozzle hole, and the number of flow passages is N-1;

[0052] Step 4: The sliding rod is connected to the third-stage blades at the end of the low-pressure cylinder of the steam turbine, and the distance between the blades is changed by adjusting the sliding rod;

[0053] Step 5: For different steam turbine blades, different blade masks are used to construct different last three-stage multi-flow channel structures;

[0054] Step 6: After the experiment, remove the last three blades of the turbine and conduct a follow-up study on blade erosion.

[0055] Taking the water erosion experiment of low-pressure last three-stage double-channel blades of a steam turbine under different loads as an example, the experimental device of water erosion of low-pressure last three-stage double-channel blades of a steam turbine under different loads is described in detail.

[0056] The air compressor is connected to the particle reactor, and brings water droplets of different diameters in the particle reactor into the main steam pipeline through the branch pipeline, and moves together with the superheated steam generated by the steam generator.

[0057] The nozzle is placed at the end of the main steam pipe, at the front end of the last stage stator blade. Figure 3As shown, a row of nozzles of different sizes are arranged in front of each sub-last-stage static blade. There are 10 nozzles, the diameter of the bottom nozzle is 20 microns, and it increases by 20 microns upwards, namely: 20 / 40 / 60 / 80 / 100 / 120 / 140 / 160 / 180 / 200 microns, and the steam with water droplets is sprayed toward the blade channel through the outlet.

[0058] The main water erosion occurs in the cylinder body, such as Figure 2 As shown in the figure, there are 18 blade specimens, including 3 each of the second-last-stage static blades, second-last-stage moving blades, second-last-stage static blades, second-last-stage moving blades, final-stage static blades and final-stage moving blades, and 3 slide bars. Among them, the second-last-stage static blades, second-last-stage moving blades, second-last-stage static blades, second-last-stage moving blades, final-stage static blades and final-stage moving blades are fixed on the slide bars in sequence to form a double flow channel.

[0059] Under the control of the vacuum valve, the vacuum pump can evacuate the cylinder to make the pressure value in the cylinder almost close to the pressure value in the last three stages of the low-pressure cylinder of the turbine under the actual rated working conditions. Then, the pressure value in the cylinder is continuously changed through the computer to achieve the pressure of different loads of the turbine.

[0060] The exhaust port can collect the condensed water in the cylinder.

[0061] The ball valve a and the pressure reducing valve are connected to the computer to control the flow rate and pressure of the steam in the main pipeline; the vortex flowmeter is connected to the computer to control, monitor and collect the flow data.

[0062] like Figure 4 As shown, the experimental method mainly includes:

[0063] Step 1: Prepare the turbine low-pressure last three-stage blade samples separately, including the second-last stage static blade, the second-last stage moving blade, the second-last stage static blade, the second-last stage moving blade, the last stage static blade, and the last stage moving blade, a total of 18 blade patterns.

[0064] Step 2: Connect the experimental device in sequence, and fix the second-last-stage stationary blades, the second-last-stage moving blades, the second-last-stage stationary blades, the second-last-stage moving blades, the last-stage stationary blades, and the last-stage moving blades on the sliding rod respectively to form a double flow channel.

[0065] Step 3: Open the vacuum valve and start the vacuum pump. Set the pressure in the cylinder to the pressure in the last three stages of the turbine under rated conditions. The pressure value is controlled by the computer display.

[0066] Step 4: The high-temperature, high-pressure, and high-speed steam generated by the steam generator and the water droplets generated by the particle generator are mixed and sprayed through three groups of 10 nozzles, a total of 30 nozzles, and enter the double channels of the last three-stage blades of the turbine.

[0067] Step 5: Set the experimental time to 1 hour. When the time is up, remove the last three-stage blades of the turbine.

Claims

1. An experimental device suitable for water erosion of different blades at the last three low-pressure stages of a steam turbine, characterized in that The experimental device includes a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a cylinder, a supporting plate, a blade cover, an exhaust port, a vacuum valve, an air pump, a computer, an air compressor, a particle generator, a ball valve b, a sub-sub-final stage stationary blade, a sub-sub-final stage moving blade, a sub-final stage stationary blade, a sub-final stage moving blade, a final stage stationary blade, a final stage moving blade, and a sliding rod, wherein: The steam generator is connected to one end of the ball valve a through the main steam pipeline, the other end of the ball valve a is connected to one end of the pressure reducing valve through the main steam pipeline, and the other end of the pressure reducing valve is connected to the vortex flowmeter through the main steam pipeline; The air compressor is connected to the particle reactor through a branch pipeline, the particle reactor is connected to one end of the ball valve b through the branch pipeline, and the other end of the ball valve b is connected to the main steam pipeline through the branch pipeline. The air compressor brings water droplets of different diameters in the particle reactor into the main steam pipeline through the branch pipeline, and moves together with the superheated steam generated by the steam generator; The nozzle is placed at the end of the main steam pipe and the front end of the second-last stator blade, and sprays the steam with water droplets toward the blade channel through the outlet; A support plate is provided in the cylinder body, a slide bar is provided on the support plate, and the second-last-stage stationary blade, the second-last-stage moving blade, the second-last-stage stationary blade, the second-last-stage moving blade, the last-stage stationary blade, and the last-stage moving blade are fixed on the slide bar in sequence to form the last three-stage blades of the low-pressure cylinder of the steam turbine, and the blade cover is placed on the last three-stage blades of the low-pressure cylinder of the steam turbine to form the last three-stage multi-flow channel structure of the low-pressure cylinder of the steam turbine; The cylinder body is provided with an exhaust port, and the exhaust port collects condensed water in the cylinder body; One end of the vacuum valve is connected to the cylinder body through a pipeline, and the other end of the vacuum valve is connected to the air pump through a pipeline. The air pump performs air extraction on the cylinder body under the control of the vacuum valve; The ball valve a and the pressure reducing valve are connected to a computer and are used to control the steam flow and steam pressure in the main steam pipeline; The vortex flowmeter is connected to a computer and is used for controlling, monitoring and collecting flow data.

2. The experimental device for water erosion of different blades of the last three low-pressure stages of a steam turbine according to claim 1 is characterized in that The total number of the sliding bars is N, and the number of the next-to-last-stage static blades, the next-to-last-stage moving blades, the next-to-last-stage static blades, the next-to-last-stage moving blades, the last-stage static blades, and the last-stage moving blades are N respectively, and the number of flow channels is N-1, and N≧3.

3. The experimental device for water erosion of different blades of the last three low-pressure stages of a steam turbine according to claim 1 is characterized in that A row of nozzles of different sizes are arranged in front of the second and last stage stationary blades along the blade height.

4. An experimental method suitable for water erosion of different blades at the last three low-pressure stages of a steam turbine, characterized in that The method comprises the following steps: Step 1: Connect the experimental device described in any one of claims 1 to 3 in sequence, and fix the second-last-stage stationary blade, the second-last-stage moving blade, the second-last-stage stationary blade, the second-last-stage moving blade, the last-stage stationary blade and the last-stage moving blade on the sliding rod. Step 2: The sliding rod is connected to the third-stage blades at the end of the low-pressure cylinder of the turbine, and the distance between the blades is changed by the sliding rod; Step 3: The blade covers are arranged on the last three-stage blades of the low-pressure cylinder of the steam turbine to form a last three-stage multi-flow channel structure of the low-pressure cylinder of the steam turbine; Step 4: Open the vacuum valve, turn on the vacuum pump, and set the pressure in the cylinder to the pressure in the last three stages of the steam turbine under rated load. The pressure value is controlled by the computer display. Then, according to the actual working pressure of the last three stages of the steam turbine, the pressure value in the device is set in sequence using the computer; Step 5: The steam generated by the steam generator and the water droplets generated by the particle generator are mixed and sprayed out through a nozzle into the multi-flow passages of the last three-stage blades of the steam turbine; Step 6: After the experiment is over, remove the third-stage blades at the end of the low-pressure cylinder of the turbine.

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