An experimental device and method for water erosion of multi-channel blades of last two stages of low-pressure turbine under different loads

Abstract

The application discloses an experimental device and method for water erosion of multi-flow-channel blades of last two stages of a steam turbine under different loads, and the experimental device comprises a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a penultimate stage static blade, a penultimate stage dynamic blade, a last stage static blade, a last stage dynamic blade, a cylinder, a fixed shaft, an exhaust port, a vacuum valve, a gas suction pump, a high-speed camera, a computer, an air compressor, a particle generator and a ball valve b. The method can be used for exploring water erosion damage of last two stages of blades of a thermal power steam turbine under different working conditions, different pressures in the cylinder are changed through the gas suction pump and computer end control, pressure values in the last two 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 two stages can be better simulated, the last two stages of blades are fixed on corresponding discs respectively, the mutual influence between the blades is considered, and the flow state of steam in the last two stages of the low-pressure cylinder of the steam turbine can be truly reflected.

Description

Technical Field

[0001] This invention belongs to the field of steam turbine technology in thermal power plants, and relates to a steam turbine blade water erosion test device and method, specifically to a test device and method for water erosion of the last two stages of multi-channel blades in the low-pressure section of a steam turbine under different loads. Background Technology

[0002] Currently, deep peak shaving of steam turbines is common to accommodate new energy sources, requiring turbines to operate under varying loads. Under these loads, especially low loads, the operating environment of the last two stages of the low-pressure turbine blades is harsh, making them susceptible to water erosion. This results in pitting and scarring on the blade surfaces, which can eventually lead to blade breakage, seriously threatening the safe and stable operation of the turbine. Therefore, to investigate the water erosion mechanism of the last two stages of thermal power turbine blades under different loads, an experimental apparatus and method for studying water erosion of multi-channel blades in the last two stages of low-pressure turbines under different loads were designed, providing a theoretical basis for the safe operation and protection of the last stage blades of steam turbines.

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

[0004] In summary, existing experimental studies on water erosion of low-pressure turbine blades do not address the multi-channel problem in the last two stages and cannot consider the mutual influence between the flow fields of each channel under different loads. Summary of the Invention

[0005] To analyze the water erosion of the blades in the last two stages of a thermal power turbine under different loads, this invention provides an experimental apparatus and method for water erosion of the blades in the last two stages of the low-pressure cylinder of a turbine under different loads, providing a theoretical basis for the safety of the blades in the last two stages of the low-pressure cylinder of a thermal power turbine under different operating conditions.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An experimental apparatus for water erosion of the last two stages of a steam turbine's low-pressure multi-channel blades under different loads includes a steam generator, ball valve a, a pressure reducing valve, a vortex flow meter, nozzles, second-to-last stage stationary blades, second-to-last stage moving blades, last-stage stationary blades, last-stage moving blades, a cylinder block, a fixed shaft, an exhaust port, a vacuum valve, a vacuum pump, a high-speed camera, a computer, an air compressor, a particle generator, and ball valve b, wherein:

[0008] 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.

[0009] 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.

[0010] The nozzle is placed at the end of the main steam pipe and at the front end of the secondary final stage stationary blade, spraying steam with water droplets into multiple channels of the blade through the outlet.

[0011] 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 respectively installed on their corresponding second-to-last stage stationary blade disk, second-to-last stage moving blade disk, last stage stationary blade disk, and last stage moving blade disk, forming a multi-channel structure in the last two stages.

[0012] The cylinder is provided with an exhaust port, which collects the water that condenses inside the cylinder.

[0013] 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.

[0014] The high-speed camera is connected to a computer to record the water erosion rate and changes on the blade surface;

[0015] 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;

[0016] The vortex flow meter is connected to a computer for the control, monitoring, and acquisition of flow data.

[0017] An experimental method for water erosion of the last two stages of a steam turbine's low-pressure multi-channel blades under different loads includes the following steps:

[0018] Step 1: Connect the experimental apparatus in sequence. 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 respectively installed on their corresponding second-to-last stage stationary blade disk, second-to-last stage moving blade disk, last stage stationary blade disk, and last stage moving blade disk to form a multi-channel structure in the last two stages.

[0019] Step 2: Open the vacuum valve, turn on the air pump, and set the pressure inside the cylinder to the pressure of the last two stages of the turbine under rated operating conditions. The pressure value is displayed and controlled by the computer.

[0020] Step 3: Mix the high-temperature, high-pressure, high-speed steam generated by the steam generator with the water droplets generated by the particle generator, and spray them out through the nozzles into the multi-flow channels of the last two stages of the steam turbine blades;

[0021] Step 4: Set the experiment time to 1 hour. After the time is up, remove the last two stages of turbine blades.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. By utilizing the impact effect of water droplets on two full-size real blades, the water erosion damage mechanism of the last two stages of low-pressure multi-channel turbine blades under different loads was studied.

[0024] 2. By using a fixed blade disk device, the curvature of multiple flow channels in each stage of the blade can be realized, which more realistically approximates the full circumference flow channel of an actual steam turbine.

[0025] 3. The number of blades in each stage can be increased or decreased based on the required number of flow channels in the last two stages of the study, while also considering the mutual influence between blades.

[0026] 4. By setting up a high-speed camera, the water erosion process can be recorded in real time from multiple angles, which is beneficial for carrying out research on the water erosion evolution process of real blades in multiple channels and full size. Attached Figure Description

[0027] Figure 1 This is an experimental block diagram of water erosion of the multi-channel blades in the last two stages of the low-pressure turbine under different loads.

[0028] Figure 2 It is a magnified view of a portion of the cylinder body;

[0029] Figure 3 This is a flowchart of the experimental method;

[0030] In the diagram: 1-Steam generator, 2-Ball valve a, 3-Pressure reducing valve, 4-Vortex flow meter, 5-Nozzle, 6-Second stage stationary vane disc, 7-Second stage moving vane disc, 8-Final stage stationary vane disc, 9-Final stage moving vane disc, 10-Cylinder block, 11-Fixed shaft, 12-Exhaust port, 13-Vacuum valve, 14-Air pump, 15-High-speed camera, 16-Computer, 17-Air compressor, 18-Particle generator, 19-Ball valve b, 20-Steam flow line. Detailed Implementation

[0031] 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.

[0032] This invention provides an experimental apparatus for water erosion of the multi-channel blades in the last two stages of the low-pressure turbine under different loads, such as... Figure 1 The device includes a steam generator 1, a ball valve a2, a pressure reducing valve 3, a vortex flow meter 4, a nozzle 5, a secondary and final stage stationary vane disc 6, a secondary and final stage moving vane disc 7, a final stage stationary vane disc 8, a final stage moving vane disc 9, a cylinder 10, a fixed shaft 11, an exhaust port 12, a vacuum valve 13, a vacuum pump 14, a high-speed camera 15, a computer 16, an air compressor 17, a pellet generator 18, and a ball valve b19, wherein:

[0033] 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.

[0034] The pressure reducing valve 3 is connected to the other end of the ball valve a through the main steam pipeline, and the pressure reducing valve 3 can regulate the steam pressure in the main steam pipeline.

[0035] 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.

[0036] The air compressor 17 is connected to the particle reactor 18 through a branch pipe. The particle reactor 18 is connected to one end of the ball valve b19 through a branch pipe. The other end of the ball valve b19 is connected to the main steam pipe through a branch pipe. The air compressor 17 carries water droplets of different diameters in the particle reactor 18 into the main steam pipe through the branch pipe, where they move together with the superheated steam generated by the steam generator 1.

[0037] 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, so that steam with water droplets is sprayed from the outlet to the blade channel.

[0038] 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 respectively installed on their corresponding second-to-last stage stationary blade disk 6, second-to-last stage moving blade disk 7, last stage stationary blade disk 8, and last stage moving blade disk 9, forming a multi-channel structure in the last two stages. Moreover, the number of blades can be increased or decreased according to the number of channels.

[0039] In the last two-stage multi-channel structure, each channel has a row of nozzles along the blade height in front of the last stage stationary blade to realistically simulate the flow of steam along the blade height. The number of nozzle rows is determined according to the number of channels.

[0040] Under the control of the vacuum valve 13, the vacuum pump 14 can perform vacuuming on the cylinder 10, so that the pressure value inside the cylinder 10 is initially set at the pressure under the rated load. By changing different pressure values ​​inside the cylinder 10, the actual pressure in the last two stages of the low pressure of the turbine under different loads can be achieved. The magnitude of the pressure value can be displayed by the computer 16.

[0041] The exhaust port 12 can collect the water that has condensed inside the cylinder 10;

[0042] The high-speed camera 15 can record the water erosion rate and changes on the blade surface;

[0043] The ball valve a and the pressure reducing valve 3 are connected to the computer 16 to control the steam flow and steam pressure in the main steam pipeline;

[0044] The vortex flow meter 4 and the high-speed camera 15 are connected to the computer 16, enabling flow monitoring and data acquisition.

[0045] This invention also provides an experimental method for water erosion of the last two stages of a steam turbine's low-pressure multi-channel blades under different loads. This method can investigate water erosion damage to the last two stages of a thermal power turbine under different operating conditions. By using an air extraction pump and computer control, different pressures within the cylinder can be changed to achieve the required pressure values ​​in the last two stages under different operating conditions. Nozzles are installed along the blade height to better simulate the steam flow state within the last two stages of the blade channels. The last two stages of blades are fixed on their corresponding disks, and the number of blades can be increased or decreased depending on the number of flow channels. The method considers the interaction between blades and can realistically reflect the steam flow state in the last two stages of the low-pressure cylinder of the steam turbine. Figure 1 As shown, the specific steps include the following:

[0046] Step 1: Prepare the blade patterns for the last two stages of the low-pressure turbine, including N blades each for the second and last stage stationary blades, the second and last stage moving blades, the last stage stationary blades, and the last stage moving blades, where N ≥ 3.

[0047] Step 2: Connect the experimental apparatus in sequence. N secondary and final stage stationary blades are fixed on the secondary and final stage stationary blade disk, N secondary and final stage moving blades are fixed on the secondary and final stage moving blade disk, N final stage stationary blades are fixed on the final stage stationary blade disk, and N final stage moving blades are fixed on the final stage moving blade disk, forming a multi-channel structure in the last two stages, with the number of channels being N-1.

[0048] Step 3: Open the vacuum valve and turn on the vacuum pump. Set the pressure inside the cylinder to the pressure of the last two stages of the turbine under rated operating conditions; the pressure value is displayed and controlled by the computer.

[0049] Step 4: Mix the high-temperature, high-pressure, high-speed steam generated by the steam generator with the water droplets generated by the particle generator, and spray them out through the nozzles into the multi-flow channels of the last two stages of the turbine blades.

[0050] Step 5: Set the experiment time to 1 hour. When the time is up, remove the last two stages of turbine blades.

[0051] Example:

[0052] Taking the water erosion test of the three-channel blades of the last two stages of the low-pressure turbine under different loads as an example, the experimental setup for water erosion of the multi-channel blades of the last two stages of the low-pressure turbine under different loads is described in detail.

[0053] An air compressor is connected to the pellet reactor, which carries water droplets of different diameters from the pellet reactor into the main steam pipe through a branch pipe, where they move together with the superheated steam generated by the steam generator.

[0054] The nozzles are placed at the end of the main steam pipe and at the front end of the secondary and final stage stator blades of the three flow channels. There are 20 nozzles at the front end of the secondary and final stage stator blades of each flow channel, which spray steam with water droplets into the blade channel through the outlet.

[0055] The main water erosion occurred in the cylinder. There were 16 blade specimens in total, consisting of 4 secondary and 4 tertiary stationary blades, 4 secondary and 4 tertiary moving blades, 4 tertiary stationary blades, and 4 tertiary moving blades. The secondary and tertiary stationary blades, the secondary and tertiary moving blades, the tertiary stationary blades, and the tertiary moving blades were fixed on their respective disks, forming three flow channels.

[0056] Under the control of the vacuum valve, the vacuum pump can evacuate air from the cylinder, making the pressure inside the cylinder almost close to the pressure in the last two stages of the low-pressure cylinder of the turbine under actual rated operating conditions. Then, the pressure inside the cylinder is continuously changed by the computer to achieve the pressure required for different turbine loads.

[0057] The exhaust port can collect the water that condenses inside the cylinder, and the high-speed camera can record the water erosion rate and changes on the blade surface.

[0058] Ball valve A and pressure reducing valve are connected to the computer to control the flow and pressure of steam in the main pipeline; vortex flow meter and high-speed camera are connected to the computer to monitor and collect flow data.

[0059] Its experimental methods mainly include:

[0060] Step 1: Prepare samples of the last two stages of the low-pressure turbine blades, including four blades each of the second and last stage stationary blades, the second and last stage moving blades, the last stage stationary blade, and the last stage moving blade, for a total of 16 blade samples.

[0061] Step 2: Connect the experimental apparatus in sequence, and fix 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 their respective disks to form three flow channels.

[0062] Step 3: Open the vacuum valve and turn on the vacuum pump. Set the pressure inside the cylinder to the rated operating pressure of the last two stages of the turbine. The pressure value is displayed and controlled by the computer.

[0063] Step 4: 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 sprayed out through three sets of 20 nozzles, for a total of 60 nozzles, into the three-flow channel of the last two stages of the steam turbine blades.

[0064] Step 5: Set the experiment time to 1 hour. After the time is up, remove the last two stages of turbine blades.

Claims

1. An experimental apparatus for water erosion of multi-channel blades in the last two stages of low-pressure turbine under different loads, characterized in that... The experimental setup includes a steam generator, ball valve a, a pressure reducing valve, a vortex flow meter, a nozzle, a secondary and final stage stationary vane, a secondary and final stage moving vane, a final stage stationary vane, a final stage moving vane, a cylinder, a fixed shaft, an exhaust port, a vacuum valve, a vacuum pump, a high-speed camera, a computer, an air compressor, a particle generator, and ball valve b, 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 secondary final stage stationary blade, spraying steam with water droplets into multiple channels of the blade through the outlet. 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 respectively installed on their corresponding second-to-last stage stationary blade disk, second-to-last stage moving blade disk, last stage stationary blade disk, and last stage moving blade disk, forming a multi-channel structure in the last two stages. The cylinder is provided with an exhaust port, which collects the water that condenses 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 high-speed camera is connected to a computer to record the water erosion rate and changes on the blade surface; 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 the low-pressure last two stages of multi-channel turbine blades under different loads as described in claim 1, characterized in that... In the last two-stage multi-channel structure, each channel has a row of nozzles arranged in front of the last stage stationary blade along the blade height to realistically simulate the flow of steam along the blade height.

3. The experimental apparatus for water erosion of the low-pressure last two stages of multi-channel turbine blades under different loads as described in claim 1, characterized in that... In the last two-stage multi-channel structure, there are N each of 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, where N ≥ 3, and the number of channels is N-1.

4. An experimental method for water erosion of multi-channel blades in the last two stages of low-pressure turbine under different loads, characterized in that... The method includes the following steps: Step 1: Connect the experimental apparatus according to any one of claims 1-2 in sequence, and install 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 their respective second-to-last stage stationary blade disk, the second-to-last stage moving blade disk, the last stage stationary blade disk, and the last stage moving blade disk to form a multi-channel structure in the last two stages. Step 2: Open the vacuum valve, turn on the air pump, and set the pressure inside the cylinder to the pressure of the last two stages of the turbine under rated operating conditions. The pressure value is displayed and controlled by the computer. Step 3: Mix the high-temperature, high-pressure, high-speed steam generated by the steam generator with the water droplets generated by the particle generator, and spray them out through the nozzles into the multi-flow channels of the last two stages of the steam turbine blades; Step 4: Set the experiment time to 1 hour. After the time is up, remove the last two stages of turbine blades.

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