Experimental device and method for water erosion of low-pressure last two-stage blades of thermal power steam turbine under deep peak regulation working condition

Abstract

The invention discloses an experimental device and method for water erosion of low-pressure last two-stage blades of a thermal power steam turbine under a deep peak regulation working condition. 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 rolling shaft, a vacuum valve, a sucking pump, a high-speed camera, a computer, an air compressor, a particle generator, a ball valve b and a high-speed motor. According to the method, water erosion damage to the last two-stage blades of the thermal power steam turbine under the deep peak regulation working condition can be explored, different pressures in a cylinder body can be changed through control of an air extracting pump and a computer end, so that pressure values in the last two stages under different working conditions in the deep peak regulation process are achieved, nozzles are arranged along the blade height, and the working efficiency is improved. The flow state of steam in the last two-stage blade channel can be better simulated, the last two-stage blades are arranged in a staggered mode, and the single flow channel of the last two-stage blades of the low-pressure cylinder of the steam turbine can be truly reflected.

Description

Technical Field

[0001] The invention relates to a turbine blade water erosion test device and method, and in particular to a thermal power steam turbine low-pressure last two-stage blade water erosion test device and method under deep peak regulation conditions. Background Art

[0002] At present, in order to absorb new energy, deep peak regulation of steam turbines is common. Under deep peak regulation conditions, the working environment of the low-pressure last two-stage blades of the steam turbine is relatively harsh, the steam humidity in the last two-stage blades is relatively high, and the last two-stage blades of the steam turbine are prone to water erosion. Small pits and pits appear on the surface of the last two-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.

[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, it is difficult to build a water erosion experimental platform using real rotating blades. Moreover, the existing technology only studies the water erosion of the last stage of the steam turbine, and has not conducted experimental research on the water erosion of the last two low-pressure blades of the steam turbine under the deep peak-shaving condition of the thermal power plant. Summary of the invention

[0005] In order to study the water erosion mechanism of the last two stage blades of a thermal power steam turbine under deep peak regulation conditions, the present invention provides an experimental device and method for water erosion of the low-pressure last two stage blades of a thermal power steam turbine under deep peak regulation conditions, which provides a theoretical basis for the safe operation and protection of the last stage blades of the turbine.

[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 blades of a thermal power steam turbine under deep peak-shaving conditions comprises a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a sub-final-stage stationary blade, a sub-final-stage moving blade, a final-stage stationary blade, a final-stage moving blade, a cylinder body, a rolling shaft, a vacuum valve, an air pump, a high-speed camera, a computer, an air compressor, a particle generator, a ball valve b, and a high-speed motor, 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 toward the blade channel through the outlet;

[0011] The sub-final-stage stationary blades and the final-stage stationary blades are fixed on the cylinder body, the sub-final-stage moving blades and the final-stage moving blades are fixed on the rolling shaft, the sub-final-stage stationary blades, the sub-final-stage moving blades, the final-stage stationary blades, and the final-stage moving blades are staggeredly installed, and the rolling shaft drives the sub-final-stage moving blades and the final-stage moving blades to rotate under the action of the high-speed motor;

[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 low-pressure last two-stage blades of a thermal power steam turbine under deep peak regulation conditions comprises the following steps:

[0018] Step 1: Connect the experimental devices in sequence, fix the second-last-stage stationary blades and the last-stage stationary blades on the cylinder body respectively, and fix the second-last-stage moving blades and the last-stage moving blades on the rolling shaft;

[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 deep peak regulation conditions. The pressure value is controlled by the computer display;

[0020] Step 3: The steam generated by the steam generator and the water droplets generated by the particle generator are mixed and sprayed out through a nozzle to enter the single flow channel of the last two stages of the turbine blades;

[0021] Step 4: Turn on the high-speed motor to drive the rolling shaft to rotate;

[0022] Step 5: After the experiment is over, remove the last two stages of blades from the turbine.

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

[0024] 1. By using the impact effect of water droplets on two-stage small-sized real blades, the water erosion damage mechanism of the last two stages of low-pressure blades of steam turbines under deep peak-shaving conditions is studied.

[0025] 2. The interaction between water vapor and water droplets on the rotating two-stage small-sized real blades is used to truly reflect the water erosion process of the low-pressure last two-stage blades during the deep peak regulation of the steam turbine;

[0026] 3. 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 small-scale real blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an experimental block diagram of water erosion of low-pressure last two-stage blades of thermal power steam turbine under deep peak-shaving conditions; in the figure: 1 steam generator, 2 ball valve a, 3 pressure reducing valve, 4 vortex flowmeter, 5 nozzle, 6 last-stage static blade, 7 last-stage moving blade, 8 last-stage static blade, 9 last-stage moving blade, 10 cylinder body, 11 rolling 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 high-speed motor;

[0028] Figure 2 It is a flow chart of the experimental method. DETAILED DESCRIPTION

[0029] 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.

[0030] The present invention provides an experimental device for water erosion of low-pressure last two-stage blades of thermal power steam turbine under deep peak load conditions, such as Figure 1As shown, 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 6, a sub-final moving blade 7, a final stationary blade 8, a final moving blade 9, a cylinder 10, a rolling 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, a ball valve b19, and a high-speed motor 20, wherein:

[0031] 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;

[0032] 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;

[0033] 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;

[0034] 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;

[0035] The nozzle 5 is placed at the end of the main steam pipe and the front end of the second-last stator blade 6, and sprays the steam with water droplets toward the blade channel through the outlet;

[0036] A row of nozzles is arranged in front of the second-last-stage stationary blade 6 along the blade height to truly simulate the flow of steam along the blade height;

[0037] The sub-final-stage stationary blades 6 and the final-stage stationary blades 8 are fixed on the cylinder body 10, the sub-final-stage moving blades 7 and the final-stage moving blades 9 are fixed on the rolling shaft 11, the sub-final-stage stationary blades 6, the sub-final-stage moving blades 7, the final-stage stationary blades 8, and the final-stage moving blades 9 are staggeredly installed, and the rolling shaft 11 drives the sub-final-stage moving blades 7 and the final-stage moving blades 9 to rotate under the action of the high-speed motor 20;

[0038] The number of the second-stage moving blades and the final-stage moving blades is 2n+2 per circle, n≧1, the blades are reduced in size by 1:5 of the actual size, and the rotation speed is set to 1000r / min;

[0039] 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 almost close to the pressure value in the last two stages of the low-pressure cylinder of the steam turbine under the actual deep peak-shaving condition. By changing the different pressure values ​​in the cylinder 10, the actual pressure in the last two stages of the low-pressure cylinder of the steam turbine under the deep peak-shaving condition can be achieved. The size of the pressure value can be displayed by the computer 16;

[0040] The exhaust port 12 can collect condensed water in the cylinder 10;

[0041] The high-speed camera 15 can record the water erosion speed and the changes in the blade surface;

[0042] 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;

[0043] The vortex flowmeter 4 and the high-speed camera 15 are connected to a computer 16 to monitor and collect flow.

[0044] The present invention also provides an experimental method for water erosion of the last two stages of low-pressure blades of a thermal power steam turbine under deep peak-shaving conditions. The method can explore the water erosion damage of the last two stages of blades of a thermal power steam turbine under deep peak-shaving conditions. Through the vacuum pump and computer-side control, the different pressures in the cylinder can be changed to achieve the pressure values ​​in the last two stages under different conditions during the deep peak-shaving process. The nozzles are set along the blade height to better simulate the flow state of steam in the last two stages of blade channels. The staggered arrangement of the last two stages of blades can truly reflect the single flow channel of the last two stages of blades of the low-pressure cylinder of the steam turbine. Figure 2 As shown, the specific steps include:

[0045] Step 1: Prepare the blade patterns of the last two low-pressure stages of the turbine respectively, including 1 second-last stage static blade, 2n+2 second-last stage moving blades, 1 last stage static blade, and 2n+2 last stage moving blades.

[0046] Step 2: Connect the experimental devices in sequence. The second-last-stage stationary blades and the last-stage stationary blades are fixed on the cylinder body respectively, and the second-last-stage moving blades and the last-stage moving blades are fixed on the rolling shaft.

[0047] 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 deep peak regulation conditions. The pressure value is controlled by the computer display.

[0048] 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 single flow channel of the last two stages of the turbine blades.

[0049] Step 5: Turn on the high-speed motor to drive the rolling shaft to rotate.

[0050] Step 6: 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 last two low-pressure blades of a steam turbine as an example, the experimental device of water erosion of the last two stages of blades of a thermal power steam turbine under deep peak regulation conditions 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 front end of the second-last-stage stator blade at the end of the main steam pipe. There are 20 nozzles along the height of the second-last-stage stator blade, 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 10 blade specimens, 1 sub-final static blade and 1 final static blade, 4 sub-final moving blades, and 4 final moving blades, which are sub-final static blades, sub-final moving blades, final static blades, and final moving blades. Among them, the sub-final static blades and final static blades are fixed on the cylinder body, and the sub-final moving blades and final moving blades are fixed on the rolling shaft. The rolling shaft drives the two moving blades to rotate under the action of the motor.

[0056] There are four sub-final blades and final blades in one circle, and the blades are reduced by 1:5 of the actual size, that is, the actual length of the sub-final blade is 100cm, and the length of the sub-final blade used in the experiment is 20cm, the actual length of the final blade is 150cm, and the length of the blade used in the experiment is 30cm. The rotation speed is set to 1000r / min.

[0057] Under the control of the vacuum valve, the vacuum pump can evacuate the cylinder body so that the pressure value in the cylinder body is almost close to the pressure value in the last two stages of the low-pressure cylinder of the turbine under the actual deep peak regulation condition.

[0058] 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.

[0059] 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.

[0060] The experimental methods mainly include:

[0061] Step 1: Prepare the turbine low-pressure last two-stage blade samples separately, including 1 second-last stage static blade, 4 second-last stage moving blades, 1 last stage static blade, and 4 last stage moving blades, for a total of 10 blade samples.

[0062] Step 2: Connect the experimental devices in sequence. The second-last-stage stationary blades and the last-stage stationary blades are fixed on the cylinder body respectively, and the second-last-stage moving blades and the last-stage moving blades are fixed on the rolling shaft.

[0063] 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 deep peak regulation conditions. The pressure value is controlled by the computer display.

[0064] 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 20 nozzles into the single flow channels of the last two stages of the turbine blades.

[0065] Step 5: Turn on the high-speed motor to drive the rolling shaft to rotate.

[0066] Step 6: 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 low-pressure last two-stage blades of thermal power steam turbine under deep peak load conditions, characterized in that The experimental device includes a steam generator, a ball valve a, a pressure reducing valve, a vortex flowmeter, a nozzle, a second-stage static blade, a second-stage moving blade, a final-stage static blade, a final-stage moving blade, a cylinder, a rolling shaft, a vacuum valve, an air pump, a high-speed camera, a computer, an air compressor, a particle generator, a ball valve b, and a high-speed motor, 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; The sub-final-stage stationary blades and the final-stage stationary blades are fixed on the cylinder body, and the sub-final-stage moving blades and the final-stage moving blades are fixed on the rolling shaft, and the rolling shaft drives the sub-final-stage moving blades and the final-stage moving blades to rotate under the action of the high-speed motor; 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 low-pressure last two-stage blades of thermal power steam turbine under deep peak load condition according to claim 1 is characterized in that A row of nozzles is arranged in front of the second-last-stage stationary blade along the blade height to truly simulate the flow of steam along the blade height.

3. The experimental device for water erosion of low-pressure last two-stage blades of thermal power steam turbine under deep peak load condition according to claim 1 is characterized in that The sub-final stage stationary blades, sub-final stage moving blades, final stage stationary blades and final stage moving blades are installed alternately.

4. The experimental device for water erosion of low-pressure last two-stage blades of thermal power steam turbine under deep peak load condition according to claim 1 is characterized in that The sub-final stage moving blades and final stage moving blades are arranged 2n+2 per circle, n≧1, the blades are reduced in size by 1:5 of the actual size, and the rotation speed is set to 1000r / min.

5. An experimental method for water erosion of low-pressure last two-stage blades of thermal power steam turbine under deep peak load conditions, characterized in that The method comprises the following steps: Step 1: Connect the experimental device described in any one of claims 1 to 4 in sequence, fix the second-last-stage stationary blade and the last-stage stationary blade on the cylinder body respectively, and fix the second-last-stage moving blade and the last-stage moving blade on the rolling shaft; 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 deep peak regulation conditions. The pressure value is controlled by the computer display; Step 3: The steam generated by the steam generator and the water droplets generated by the particle generator are mixed and sprayed out through a nozzle to enter the single flow channel of the last two stages of the turbine blades; Step 4: Turn on the high-speed motor to drive the rolling shaft to rotate; Step 5: After the experiment is over, remove the last two stages of blades from the turbine.

Images