Experimental device and method for water erosion of low-pressure last two-stage multi-runner blade of steam turbine under different loads

Abstract

The invention discloses an experimental device and method for water erosion of low-pressure last two-stage multi-runner blades of a steam turbine under different loads. The experimental device comprises a steam generator, a ball valve a, a pressure reducing valve, a vortex shedding flowmeter, a nozzle, a penultimate-stage stationary blade, a penultimate-stage movable blade, a final-stage stationary blade, a final-stage movable blade, a cylinder body, a fixed shaft, an exhaust port, a vacuum valve, an air pump, a high-speed camera, a computer, an air compressor, a particle generator and a ball valve b. According to the method, the water erosion damage of the last two-stage blade of the thermal power steam turbine under different working conditions can be explored, different pressures in the cylinder body are controlled and changed through the sucking pump and the computer end so as to reach the pressure value in the last two-stage blade under different working conditions, the nozzle is arranged along the blade height, the flowing state of steam in the last two-stage blade channel can be better simulated, and the water erosion damage of the last two-stage blade of the thermal power steam turbine is simulated. The last two stages of blades are respectively fixed on the corresponding discs, the mutual influence between the blades is considered, and the flowing 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] 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 to a steam turbine low-pressure last two-stage multi-channel blade water erosion test device and method under different loads. Background Art

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

[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 experimental research on water erosion of low-pressure turbine blades does not involve the problem of multi-flow channels in the last two stages, and cannot consider the mutual influence relationship between the flow fields of each flow channel under different loads. Summary of the invention

[0005] In order to analyze the water erosion of the blades of the last two stages of multi-channels of a thermal power steam turbine under different loads, the present invention provides an experimental device and method for water erosion of the blades of the last two stages of multi-channels of a low-pressure cylinder of a thermal power steam turbine under different loads, providing a theoretical basis for the safety of the blades of the last two stages of multi-channels of a low-pressure cylinder of a thermal power steam turbine under different working conditions.

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

[0007] An experimental device for water erosion of low-pressure last two-stage multi-channel blades of a steam turbine under different loads includes a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a sub-last stage stationary blade, a sub-last stage moving blade, a last stage stationary blade, a last stage moving blade, a cylinder body, a fixed shaft, an exhaust port, a vacuum valve, an air pump, a high-speed camera, a computer, an air compressor, a particle generator, and a ball valve b, wherein:

[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 to multiple channels of the blade through the outlet;

[0011] The sub-final-stage stationary blades, sub-final-stage moving blades, final-stage stationary blades, and final-stage moving blades are respectively mounted on their corresponding sub-final-stage stationary blade discs, sub-final-stage moving blade discs, final-stage stationary blade discs, and final-stage moving blade discs to form a final two-stage multi-flow channel structure;

[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, and 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 and is used to record the water erosion speed and the changes on the blade surface;

[0015] 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;

[0016] The vortex flowmeter is connected to a computer and is used for controlling, monitoring and collecting flow data.

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

[0018] Step 1: Connect the experimental devices in sequence, and install the next-to-last-stage stationary blades, the next-to-last-stage moving blades, the last-stage stationary blades, and the last-stage moving blades on their corresponding next-to-last-stage stationary blade discs, the next-to-last-stage moving blade discs, the last-stage stationary blade discs, and the last-stage moving blade discs, respectively, to form a last two-stage multi-flow channel structure;

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

[0020] 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 sprayed out through the nozzle to enter the multi-flow passages of the last two stages of the turbine blades;

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

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

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

[0024] 2. The fixed blade disc device can realize the curvature of multiple flow channels of each blade stage, which is more realistic and close to the full-circle flow channel of the actual steam turbine;

[0025] 3. According to the requirements of the number of blade flow channels at the last two stages of the study, and considering the mutual influence between blades, the number of blades at each stage can be increased or decreased;

[0026] 4. By setting up a high-speed camera, the water erosion process can be recorded in real time from multiple angles, which is conducive to the study of the water erosion evolution process of multi-channel full-size real blades. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 This is a partial enlarged view of the cylinder body;

[0029] Figure 3 It is a flow chart of the experimental method;

[0030] In the figure: 1-steam generator, 2-ball valve a, 3-pressure reducing valve, 4-vortex flowmeter, 5-nozzle, 6-second-stage static blade disc, 7-second-stage moving blade disc, 8-last-stage static blade disc, 9-last-stage moving blade disc, 10-cylinder body, 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 streamline. DETAILED DESCRIPTION

[0031] 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.

[0032] The present invention provides an experimental device for water erosion of the last two-stage multi-channel blades of a steam 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 flowmeter 4, a nozzle 5, a sub-final stationary blade disc 6, a sub-final moving blade disc 7, a final stationary blade disc 8, a final moving blade disc 9, a cylinder 10, a fixed shaft 11, an exhaust port 12, a vacuum valve 13, an air pump 14, a high-speed camera 15, a computer 16, an air compressor 17, a particle generator 18, and a ball valve b19, wherein:

[0033] 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;

[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 adjust the steam pressure in the main steam pipeline;

[0035] 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;

[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 the branch pipe, and the other end of the ball valve b19 is connected to the main steam pipe through the branch pipe. The air compressor 17 brings water droplets of different diameters in the particle reactor 18 into the main steam pipe through the branch pipe, and moves 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 the front end of the second-last stator blade, and sprays the steam with water droplets toward the blade channel through the outlet;

[0038] The sub-final stationary blades, sub-final moving blades, final stationary blades, and final moving blades are respectively mounted on their corresponding sub-final stationary blade discs 6, sub-final moving blade discs 7, final stationary blade discs 8, and final moving blade discs 9 to form a final two-stage multi-flow channel structure, and the number of blades can be increased or decreased according to the number of flow channels;

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

[0040] The vacuum pump 14, under the control of the vacuum valve 13, can perform vacuum processing on the cylinder 10, so that the pressure value in the cylinder 10 is first set to the pressure under the rated load, and by changing the different pressure values ​​in the cylinder 10, the actual pressure in the low-pressure last two stages of the steam turbine under different loads can be achieved, and the size of the pressure value can be displayed by the computer 16;

[0041] The exhaust port 12 can collect condensed water in the cylinder 10;

[0042] The high-speed camera 15 can record the water erosion speed and the changes in 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 flowmeter 4 and the high-speed camera 15 are connected to a computer 16 to monitor and collect flow.

[0045] The present invention also provides an experimental method for water erosion of multi-channel blades in the last two low-pressure stages of a steam turbine under different loads. The method can be used to explore water erosion damage to the last two blades of a thermal power steam turbine under different working conditions. 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 two stages under different working conditions. Nozzles are set along the blade height to better simulate the flow state of steam in the last two blade channels. The last two blades are respectively fixed on their corresponding discs. The number of blades can be increased or decreased according to the number of channels. The mutual influence between blades is taken into account, and the flow state of steam in the last two stages of the low-pressure cylinder of the steam turbine can be truly reflected. Figure 1 As shown, the specific steps include:

[0046] Step 1: Prepare the blade patterns of the last two low-pressure stages of the turbine respectively, including N blades of the next-last stage static blade, N-last stage moving blade, N-last stage static blade, and N-last stage moving blade, and N≧3.

[0047] Step 2: Connect the experimental devices in sequence, N next-to-last stage static blades are fixed on the next-to-last stage static blade disk, N next-to-last stage moving blades are fixed on the next-to-last stage moving blade disk, N last-stage static blades are fixed on the last-stage static blade disk, and N last-stage moving blades are fixed on the last-stage moving blade disk, forming a last two-stage multi-channel structure with N-1 channels.

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

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

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

[0051] Example:

[0052] Taking the water erosion experiment of the low-pressure last two-stage three-channel blades of a steam turbine under different loads as an example, the experimental device of water erosion of the low-pressure last two-stage multi-channel blades of a steam turbine under different loads is described in detail.

[0053] 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.

[0054] The nozzle is placed at the end of the main steam pipe, at the front end of the next-to-last stator blades of the three flow channels. There are 20 nozzles at the height of the next-to-last stator blades at the front of each flow channel, and the steam with water droplets is sprayed toward the blade channel through the outlet.

[0055] The main water erosion is carried out in the cylinder body. There are 16 blade specimens, including 4 sub-final static blades, 4 sub-final moving blades, 4 final static blades and 4 final moving blades. Among them, the sub-final static blades, sub-final moving blades, final static blades and final moving blades are fixed on their corresponding discs to form three flow channels.

[0056] 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 two stages of the low-pressure cylinder of the steam 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 steam turbine.

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

[0058] 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 and the high-speed camera are connected to the computer to monitor and collect the flow data.

[0059] The experimental methods mainly include:

[0060] Step 1: Prepare the turbine low-pressure last two-stage blade samples separately, including the next-last-stage static blade, the next-last-stage moving blade, the last-stage static blade, and the last-stage moving blade, 4 blades in total, 16 blade samples.

[0061] Step 2: Connect the experimental devices in sequence, and fix the next-to-last-stage stationary blades, the next-to-last-stage moving blades, the last-stage stationary blades, and the last-stage moving blades on their corresponding disks to form three flow channels.

[0062] Step 3: Open the vacuum valve and start the vacuum pump. Set the pressure in the cylinder to the pressure in the last two stages of the turbine under rated conditions. The pressure value is controlled by the computer display.

[0063] 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 20 nozzles, a total of 60 nozzles, and enter the three flow channels of the last two stages of the turbine blades.

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

Claims

1. An experimental device for water erosion of multi-channel blades at the last two low-pressure stages of a steam turbine under different loads, characterized in that The experimental device includes a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a sub-final stationary blade, a sub-final moving blade, a final stationary blade, a final moving blade, a cylinder, a fixed shaft, an exhaust port, a vacuum valve, an air pump, a high-speed camera, a computer, an air compressor, a particle generator, and a ball valve b, 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 to multiple channels of the blade through the outlet; The sub-final-stage stationary blades, sub-final-stage moving blades, final-stage stationary blades, and final-stage moving blades are respectively mounted on their corresponding sub-final-stage stationary blade discs, sub-final-stage moving blade discs, final-stage stationary blade discs, and final-stage moving blade discs to form a final two-stage multi-flow channel structure; 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, and 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 and is used to record the water erosion speed and the changes on the blade surface; 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 the last two-stage multi-channel blades of a steam turbine under different loads according to claim 1 is characterized in that In the last two-stage multi-channel structure, a row of nozzles is arranged in front of the second-last-stage stationary blade along the blade height in each flow channel to truly simulate the flow of steam along the blade height.

3. The experimental device for water erosion of the last two-stage multi-channel blades of a steam turbine under different loads according to claim 1 is characterized in that In the last two-stage multi-flow channel structure, there are N next-to-last-stage stationary blades, N next-to-last-stage moving blades, last-stage stationary blades, and last-stage moving blades, N≧3, and the number of flow channels is N-1.

4. An experimental method for water erosion of multi-channel blades at the last two low-pressure stages of a steam turbine under different loads, characterized in that The method comprises the following steps: Step 1: Connect the experimental device described in any one of claims 1-2 in sequence, and install the next-to-last-stage stationary blades, the next-to-last-stage moving blades, the last-stage stationary blades, and the last-stage moving blades on their corresponding next-to-last-stage stationary blade discs, the next-to-last-stage moving blade discs, the last-stage stationary blade discs, and the last-stage moving blade discs, respectively, to form a last two-stage multi-channel structure; Step 2: Open the vacuum valve, turn on the vacuum pump, and set the pressure in the cylinder to the pressure in the last two stages of the steam turbine under rated conditions. The pressure value is controlled by the computer display; 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 sprayed out through the nozzle to enter the multi-flow passages of the last two-stage blades of the steam turbine; Step 4: Set the experimental time to 1 hour. When the time is up, remove the last two stages of blades of the turbine.

Images