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

Abstract

The application discloses an experimental device and method suitable for water erosion of different blades of low-pressure last three stages of a steam turbine, and the experimental device 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, a gas suction pump, a computer, an air compressor, a particle generator, a ball valve b, a second last stage static blade, a second last stage moving blade, a last stage static blade, a last stage moving blade, a last stage static blade, a last stage moving blade and a sliding rod. The method can be used for studying water erosion damage of different blades, the different pressure in the cylinder body is changed through the gas suction pump and computer terminal control, the pressure values in the last three stages under different working conditions are achieved, the nozzle is arranged along the height of the blade, the flow state of steam in the blade passage of the last three stages is better simulated, the last three stage blades are fixed on the sliding rod, and the mutual influence between the blades is considered. Different sizes of the blade cover can be used for constructing the flow field structure of the last three stages of different blades.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steam turbine of thermal power plant, and relates to a steam turbine blade water erosion experimental device and method, in particular to an experimental device and method suitable for water erosion of different blades of low-pressure last three stages of a steam turbine. BACKGROUND

[0002] At present, in order to accommodate new energy, deep peak shaving of most steam turbines is common, and the steam turbine needs to be operated at different loads. Under different loads, especially under low load, the working environment of the low-pressure last three stages of the steam turbine is relatively poor, and the last three stages of the steam turbine are prone to water erosion. Small pits and pockmarks appear on the surface of the last three stages of the steam turbine, and over a long period of time, the blade may even be broken, which seriously threatens 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 low-pressure last three stages of the steam turbine are designed, which provides a theoretical basis for the safe operation and protection of the last stage blades of the steam turbine.

[0003] CN100575917C discloses a steam turbine blade water erosion test device, which uses the collision between high-speed rotating blades and water droplets to simulate the water erosion of the blades 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 through the collision between high-pressure pulse water jet and the test piece; CN102252927B discloses a high-pressure water jet rotary impact water erosion experimental device, which simulates the erosion of water droplets on the blades in the steam turbine through the collision between high-speed jet and rotating test piece; and CN113267416B discloses a nuclear power plant steam turbine blade dynamic water erosion experimental device, which can realize accelerated experiment of the water erosion process of the nuclear power steam turbine blades.

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

[0005] In order to analyze the water erosion mechanism of different blades, the present application provides an experimental device and method suitable for water erosion of different blades of the low-pressure last three stages of the steam turbine, which provides a theoretical basis for the safety of the last three stages of multi-flow passage blades of the low-pressure cylinder of the thermal power steam turbine under different working conditions.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] An experimental device suitable for water erosion of different blades of the last three stages of a low-pressure turbine cylinder, comprising a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a cylinder, a support plate, a blade cover, an exhaust port, a vacuum valve, a vacuum pump, a computer, an air compressor, a particle generator, a ball valve b, a penultimate stage stator, a penultimate stage rotor, a last stage stator, a last stage rotor, a last stage stator, a last stage rotor, and a slide rod, wherein:

[0008] The steam generator is connected to one end of the ball valve a through a 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 a branch pipeline, the other end of the ball valve b is connected to the main steam pipeline through a branch pipeline, and the air compressor brings water droplets of different diameters in the particle reactor into the main steam pipeline through a branch pipeline, which moves together with the superheated steam generated by the steam generator;

[0010] The nozzle is placed at the end of the main steam pipeline and the front end of the penultimate stage stator, and the steam with water droplets is sprayed into the blade passage through the outlet;

[0011] The support plate is arranged in the cylinder, the support plate is provided with the slide rod, the penultimate stage stator, the penultimate stage rotor, the last stage stator, the last stage rotor, the last stage stator, and the last stage rotor are sequentially fixed on the slide rod to form the last three stages of the low-pressure cylinder of the turbine, and the blade cover is placed on the last three stages of the low-pressure cylinder of the turbine to form a multi-channel structure of the last three stages of the low-pressure cylinder of the turbine;

[0012] The cylinder is provided with an exhaust port for collecting condensed water in the cylinder;

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

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

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

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

[0017] Step 1: sequentially connect the above experimental device, fix the penultimate stage stator, the penultimate stage rotor, the last stage stator, the last stage rotor, the last stage stator, and the last stage rotor on the slide rod,

[0018] Step 2: the slide bar is connected with the last three-stage blade of the low-pressure cylinder of the steam turbine, and the distance between the blades is changed through the slide bar;

[0019] Step 3: the blade cover is arranged on the last three-stage blade of the low-pressure cylinder of the steam turbine, and a multi-channel structure of the last three-stage blade of the low-pressure cylinder of the steam turbine is formed;

[0020] Step 4: the vacuum valve is opened, the steam pump is opened, the pressure in the cylinder is set to the pressure in the last three-stage blade of the steam turbine under the rated load, the pressure value is displayed and controlled by the computer, and then the pressure value in the device is set by the computer according to the actual working pressure of the last three-stage blade of the steam turbine;

[0021] Step 5: the steam generated by the steam generator and the water droplets generated by the particle generator are mixed and sprayed through the nozzle into the multi-channel of the last three-stage blade of the steam turbine;

[0022] Step 6: the last three-stage blade of the low-pressure cylinder of the steam turbine is taken off after the experiment is completed.

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

[0024] 1. The water droplet impact effect on the three-stage full-size real blade is utilized to realize the water erosion damage mechanism research of the last three-stage blade of the low-pressure multi-channel of the steam turbine.

[0025] 2. The blade cover of different sizes can construct different last three-stage flow field structures for different blades, and the water erosion of the last three-stage blade of the steam turbine can be researched by replacing the blade cover.

[0026] 3. The distance between the blades can be changed by using the slide bar connected with the blade, and the influence of the distance between the blades on the water erosion of the steam turbine is analyzed.

[0027] 4. The nozzles of different diameters are arranged along the blade height, so that the flow state of the steam and the water droplets in the multi-channel of the last three-stage blade can be more accurately simulated. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is an experimental block diagram suitable for water erosion of different blades of the last three-stage of the low-pressure cylinder of the steam turbine.

[0029] Figure 2 is an enlarged view of the local part in the cylinder.

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

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

[0032] In the diagram: 1-Steam generator, 2-Ball valve a, 3-Pressure reducing valve, 4-Vortex flow meter, 5-Nozzle, 6-Nozzle orifice, 7-Cylinder body, 8-Support plate, 9-Blade shield, 10-Exhaust port, 11-Vacuum valve, 12-Air pump, 13-Computer, 14-Air compressor, 15-Particle generator, 16-Ball valve b, 17-Second stage stationary vane, 18-Second stage moving vane, 19-Second stage stationary vane, 20-Second stage moving vane, 21-Final stage stationary vane, 22-Final stage moving vane, 23-Slide rod. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0034] This invention provides an experimental apparatus suitable for water erosion of different blades in the last three stages of a low-pressure turbine, such as... Figure 1 As shown, the experimental apparatus includes a steam generator 1, ball valve a2, pressure reducing valve 3, vortex flow meter 4, nozzle 5, nozzle orifice 6, cylinder 7, support plate 8, blade shield 9, exhaust port 10, vacuum valve 11, vacuum pump 12, computer 13, air compressor 14, pellet generator 15, ball valve b16, secondary final stage stationary vane 17, secondary final stage moving vane 18, secondary final stage stationary vane 19, secondary final stage moving vane 20, final stage stationary vane 21, final stage moving vane 22, and slide bar 23, wherein:

[0035] The steam generator 1 is connected to one end of the ball valve a2 via the main steam pipeline. The temperature and pressure of the steam at the outlet 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. The pressure reducing valve 3 can regulate the steam pressure in the main steam pipeline.

[0037] The vortex flow meter 4 is connected to the pressure reducing valve 3 through the main steam pipeline, and the vortex flow meter 4 can measure the steam flow rate 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 a branch pipe. The other end of the ball valve b16 is connected to the main steam pipe through a branch pipe. The air compressor 14 carries water droplets of different diameters in the particle reactor 15 into the main steam pipe through the branch pipe, where they move 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 at the front end of the secondary final stage stationary blade 17, so that steam with water droplets is sprayed from the outlet to the blade channel.

[0040] Supporting plate 8 is arranged in the cylinder 7, and a slide rod 23 is fixed on the supporting plate 8. The next-to-last-stage static blade 17, the next-to-last-stage moving blade 18, the last-but-one static blade 19, the last-but-one moving blade 20, the last-stage static blade 21 and the last-stage moving blade 22 are sequentially fixed on the slide rod 23 in order and can slide to form the last three-stage blades of the low-pressure cylinder of the steam turbine. Different last three-stage blades of different steam turbines can be replaced for testing. The total number of the slide rods 23 is N, and the total number of the next-to-last-stage static blades, the next-to-last-stage moving blades, the last-but-one static blades, the last-but-one moving blades, the last-stage static blades and the last-stage moving blades is 6N. These blades are fixed on the corresponding slide rods 23 to form a multi-channel structure of the last three-stage blades of the low-pressure cylinder of the steam turbine. The number of the blades can be increased or decreased according to the number of the channels.

[0041] The blade cover 9 is placed on the last three-stage blades of the low-pressure cylinder of the steam turbine to better form the flow field structure of the last three stages. Different sizes of the cover can be replaced according to the sizes of different blades.

[0042] The slide rod 23 is connected with the last three-stage blades of the low-pressure cylinder of the steam turbine to change the distance between the blades.

[0043] A row of nozzles with different sizes is arranged in front of each next-to-last-stage static blade 17 along the blade height to simulate the flow of steam along the blade height. The number of the rows of the nozzles is determined according to the number of the channels.

[0044] The steam extraction pump 12 is controlled by the vacuum valve 11 to perform steam extraction on the cylinder 7. The pressure value in the cylinder 7 is set at the pressure under the rated load for the first time. Different pressure values in the cylinder 7 are changed to achieve the real pressure in the low-pressure last three stages of the steam turbine under different loads. The size of the pressure value can be displayed by the computer 13.

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

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

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

[0048] The application also provides an experimental method suitable for water erosion of different blades of low-pressure last three stages of a steam turbine, which can study the water erosion damage of different blades, and through the air pump and computer terminal control, different pressures in the cylinder can be changed to achieve the pressure values in the last three stages under different working conditions, the nozzles are arranged along the height of the blade, the flow state of steam in the blade passage of the last three stages can be better simulated, the last three stage blades are fixed on the slide rods, the distance between the blades can be adjusted, and the mutual influence between the blades is considered. The blade cover can be selected according to the size of the research blade, and the blade cover is used to build the flow field structure of the last three stages. As shown in Figure 1 the following steps are specifically included:

[0049] Step 1: sequentially connect the experimental device, N roots of the second last stage stator blade, N roots of the second last stage rotor blade, N roots of the second last stage stator blade, N roots of the second last stage rotor blade, N roots of the last stage stator blade, and N roots of the last stage rotor blade are fixed on N roots of the slide rods according to the examples in the drawings, and N is greater than or equal to 3;

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

[0051] Step 3: mix the high-temperature, high-pressure and high-speed steam generated by the steam generator and the water droplets generated by the particle generator, and enter the steam turbine last three stage blade multi-flow channel through the nozzle on the nozzle hole. The number of flow channels is N-1;

[0052] Step 4: the slide rod is connected with the last three stage blades of the low-pressure cylinder of the steam turbine, and the distance between the blades is changed by adjusting the slide rod;

[0053] Step 5: different blade covers are used for different steam turbine blades to build different last three stage multi-flow channel structures;

[0054] Step 6: after the experiment, the last three stage blades of the steam turbine are taken out for subsequent research on the water erosion of the blades.

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

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

[0057] The nozzle is arranged at the end of the main steam pipeline, in front of the second last stage stator blade, as Figure 3As shown, a row of nozzles of different sizes is arranged in front of each sub-last stator blade, and the number of nozzles is 10, the diameter of the bottom nozzle is 20 microns, and the diameter of the upper nozzle is increased by 20 microns, that is, 20 / 40 / 60 / 80 / 100 / 120 / 140 / 160 / 180 / 200 microns, and the steam with water droplets is sprayed into the blade passage.

[0058] The main water erosion is carried out in the cylinder, such as Figure 2 As shown, the blade test piece has a total of 18, 3 sub-last stator blades, 3 sub-last rotor blades, 3 sub-last stator blades, 3 sub-last rotor blades, 3 last stator blades and 3 last rotor blades, and 3 slide rods.

[0059] Under the control of the vacuum valve, the exhaust pump can perform exhaust treatment on the cylinder, so that the pressure value in the cylinder is close to the pressure value in the last three stages of the low-pressure cylinder of the steam turbine under the actual rated working condition. Then, the pressure value in the cylinder is changed by the computer to achieve the pressure of the steam turbine under different loads.

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

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

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

[0063] Step 1: Prepare turbine low-pressure last three stage blade samples, including sub-last stator blades, sub-last rotor blades, sub-last stator blades, sub-last rotor blades, last stator blades and last rotor blades, a total of 18 blade samples.

[0064] Step 2: Connect the experimental device in sequence, fix the sub-last stator blades, sub-last rotor blades, sub-last stator blades, sub-last rotor blades, last stator blades and last rotor blades on the slide rods to form double flow channels.

[0065] Step 3: Open the vacuum valve and open the exhaust pump. Set the pressure in the cylinder to the pressure in the last three stages of the steam turbine under the rated working condition, and the pressure value is displayed and controlled by the computer.

[0066] Step 4: Mix the high-temperature, high-pressure and high-speed steam generated by the steam generator with the water droplets generated by the particle generator, and spray them out through three groups of 10 nozzles, a total of 30 nozzles, into the turbine last three stage blade double channels.

[0067] Step 5: Set the experiment time for 1 hour. At the end of the time, remove the last three stages of the turbine.

Claims

1. An experimental apparatus suitable for water erosion of different blades in the last three stages of a steam turbine's low-pressure section, characterized in that... The experimental apparatus includes a steam generator, ball valve a, a pressure reducing valve, a vortex flow meter, a nozzle, a cylinder, a support plate, a blade shield, an exhaust port, a vacuum valve, a vacuum pump, a computer, an air compressor, a pellet generator, ball valve b, a secondary final stage stationary vane, a secondary final stage moving vane, a secondary final stage stationary vane, a secondary final stage moving vane, a final stage stationary vane, a final stage moving vane, and a slide bar, wherein: The steam generator is connected to one end of ball valve a via the main steam pipeline, and the other end of ball valve a is connected to one end of pressure reducing valve via the main steam pipeline. The other end of pressure reducing valve is connected to vortex flow meter via the main steam pipeline. The air compressor is connected to the particle reactor through a branch pipe. The particle reactor is connected to one end of the ball valve b through a branch pipe. The other end of the ball valve b is connected to the main steam pipe through a branch pipe. The air compressor carries water droplets of different diameters in the particle reactor into the main steam pipe through the branch pipe, where they move together with the superheated steam generated by the steam generator. The nozzle is placed at the end of the main steam pipe and at the front end of the last stage stationary blade, so that steam with water droplets is sprayed from the outlet to the blade channel. The cylinder body is provided with a support plate, and a slide bar is provided on the support plate. The second-to-last stage stationary blade, the second-to-last stage moving blade, the second-to-last stage stationary blade, the second-to-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 stages of the turbine low-pressure cylinder blades. The blade shield is placed on the last three stages of the turbine low-pressure cylinder blades to form a multi-channel structure of the last three stages of the turbine low-pressure cylinder. The cylinder is provided with an exhaust port, which collects the condensed water inside the cylinder. One end of the vacuum valve is connected to the cylinder body through a pipe, and the other end of the vacuum valve is connected to the air pump through a pipe. 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 used to control the steam flow and steam pressure in the main steam pipeline; The vortex flow meter is connected to a computer for the control, monitoring, and acquisition of flow data.

2. The experimental apparatus for water erosion of different blades in the last three stages of low-pressure turbines according to claim 1, characterized in that... The total number of slide bars is N, with N each for the second-to-last stage stationary blade, the second-to-last stage moving blade, the second-to-last stage stationary blade, the second-to-last stage moving blade, the last stage stationary blade, and the last stage moving blade. The number of flow channels is N-1, and N≧3.

3. The experimental apparatus for water erosion of different blades in the last three stages of low-pressure turbines according to claim 1, characterized in that... Each of the last stage blades has a row of nozzles of different sizes along its height.

4. An experimental method suitable for water erosion of different blades in the last three stages of low-pressure turbines, characterized in that... The method includes the following steps: Step 1: Connect the experimental apparatus according to any one of claims 1-3 in sequence, and fix the second-to-last stage stationary blade, the second-to-last stage moving blade, the second-to-last stage stationary blade, the second-to-last stage moving blade, the last stage stationary blade, and the last stage moving blade on the slide rod. Step 2: The slide bar is connected to the last three-stage blades of the low-pressure cylinder of the steam turbine, and the distance between the blades is changed by the slide bar; Step 3: The blade shields are arranged on the last three-stage blades of the low-pressure cylinder of the steam turbine to form a multi-channel structure of the last three stages of the low-pressure cylinder of the steam turbine. Step 4: Open the vacuum valve, turn on the air pump, and set the pressure inside the cylinder to the pressure of the last three stages of the steam turbine under rated load. The pressure value is displayed and controlled by the computer. Then, according to the actual working pressure of the last three stages of the steam turbine, use the computer to set the pressure value inside the device in sequence. Step 5: Mix the steam generated by the steam generator and the water droplets generated by the particle generator, and spray them out through the nozzle into the multi-flow channel of the last three stages of the steam turbine blades; Step 6: After the experiment, remove the last three-stage blades of the low-pressure cylinder of the steam turbine.

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