Online measurement method and device for opening degree of movable blade of fan blade

Abstract

The invention discloses an on-line measurement method and device for the opening degree of a movable blade of a fan blade, relates to an arrangement scheme of on-line monitoring sensors for the opening degree of the fan blade of a power station and a test method of the on-line monitoring sensors, and the application object of the method is a movable blade adjusting type axial flow fan of the power station. According to the method, based on a blade tip timing method, a blade tip sensor is arranged at a specific position, corresponding to a machine shell, of a power station fan impeller sweeping area, a key phase sensor is arranged at a specific position of a fan main shaft, and signals generated when different positions of fan blade tips pass through the blade tip sensor are measured; phase information of different axial positions of the fan blade relative to the key phase zero point is obtained through calculation, and actual opening propeller angle information of the fan blade is obtained through conversion. The information can be used for blade opening asynchronous fault diagnosis of a power station fan, and the problem that the actual blade opening of a movable blade adjusting type axial flow fan is difficult to monitor is solved. The method is simple in principle and easy to apply, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the field of online monitoring of power station fans, and in particular relates to an online measurement method and device for the opening of moving blades of fan blades. Background Art

[0002] The blade-adjustable axial flow fan is an important ventilation equipment. Its characteristic is that the blade angle can be changed by adjusting the rotation position of the blade, so as to achieve precise control of the air volume and air pressure. The working principle of the blade-adjustable axial flow fan is relatively complex but efficient. When the airflow flows into the fan from the system pipeline, it first changes direction through the air box, then flows through the collector to converge and accelerate, and then flows to the impeller. The motor provides power to the impeller so that it can do work on the airflow. The working angle and blade pitch of the blade can be adjusted steplessly, so that the air volume and air pressure can be changed according to the changing requirements of the working conditions. The airflow after flowing through the impeller is a rotational motion, which is converted into axial flow into the diffuser through the rear guide vane. In the diffuser, part of the kinetic energy of the gas is converted into static pressure energy, and then flows to the system to meet the operating requirements, thereby completing the working process of the fan output.

[0003] Compared with centrifugal fans and stationary blade-adjustable fans, the axial flow fans with adjustable blades have significant advantages in terms of economy due to their small size, light weight, high efficiency in low-load areas, wide adjustment range, and fast response speed. Therefore, they are widely used to replace old centrifugal fans in energy-saving technology transformation projects of domestic coal-fired power plants.

[0004] The blade adjustment mechanism of the blade-adjustable axial flow fan is relatively complex. Generally, the slider on the crank at the root of the blade is driven by a hydraulic cylinder and an actuator disc to drive the crank to swing, so that the blade rotates around the opening adjustment shaft to achieve the purpose of changing the blade opening. In actual operation, under the influence of unfavorable conditions such as corrosive exhaust gas, vibrating alternating loads and centrifugal loads, the blade-adjustable axial flow fan is prone to mechanical failures such as crank deformation, rust and wear of the slider or actuator disc after a period of operation, resulting in the blade opening being out of sync during the adjustment process or the actual blade opening being different from the controlled opening, which affects the fan's working efficiency and increases the fan's vibration.

[0005] The existing blade-adjustable axial flow fans mainly rely on the control system feedback values ​​such as the actuation stroke of the actuating mechanism or the amount of hydraulic oil pumped in to monitor the blade opening. When the end of the actuating structure such as the slider, actuating disc or crank fails, the control system cannot correctly feedback the actual opening of the blade. Therefore, it is necessary to set up a blade opening online measurement system independent of the control system.

[0006] At present, some studies use pressure sensors to try to indirectly measure the opening of fan blades from the flow field characteristics at the impeller outlet and diagnose problems such as signal opening asynchrony. This technical solution is difficult to calibrate and is easily affected by other flow field factors. It cannot accurately monitor the opening of the moving blades and can only monitor more serious blade opening asynchrony faults. Summary of the invention

[0007] The purpose of the present invention is to provide a method and device for online measurement of the opening of moving blades of fan blades. The present invention is applied to a moving blade-adjustable axial flow fan in a power station. The actual opening of each blade of the fan can be measured during the operation of the fan, and is used to diagnose faults such as blade adjustment asynchrony and blade adjustment failure during the operation of the moving blade-adjustable axial flow fan.

[0008] In order to achieve the above object, the present invention adopts the following technical solution: The present invention provides an online measuring device for the opening of a fan blade, comprising a key phase sensor, an opening sensor, a rotating shaft sensor and a key phase measuring point; The key phase sensor is installed at the fan coupling or motor output shaft in a non-contact manner, and a key phase signal is obtained every time it rotates one circle; the opening sensor and the shaft sensor are installed on the casing through the casing opening; the key phase measurement points are arranged so that the key phase calculation starting point is within the angle range formed by the leading edge of the blade and the previous blade opening adjustment rotating axis when the blade opening is minimum.

[0009] A further improvement of the present invention is that the key phase sensor and the opening sensor are arranged in the same phase.

[0010] A further improvement of the present invention is that the key phase is obtained by a photoelectric sensor in combination with reflective paper.

[0011] A further improvement of the present invention is that the key phase is obtained by means of an eddy current sensor in combination with a key slot.

[0012] A further improvement of the present invention is that the opening sensor is a blade tip sensor for recording the blade tip passing signal. The sensor type is a fiber optic sensor or an eddy current sensor, which is radially installed on the casing in the blade rotation plane. The axial position of the sensor center line along the fan shaft is located in front of or behind the blade opening adjustment rotating axis. When the sensor arrangement space permits, it should be preferentially arranged in front of the blade opening adjustment rotating axis.

[0013] A further improvement of the present invention is that the shaft sensor is a blade tip sensor for recording the blade tip passing signal, the sensor type is a fiber optic sensor or an eddy current sensor, which is radially installed on the casing within the blade rotation plane, and the axial position of the sensor center line along the fan shaft is the same as the axial position of the blade opening adjustment rotating shaft.

[0014] A further improvement of the present invention is that the key phase sensor cooperates with the key phase measuring point to measure the rotation speed of the fan rotor and provide key phase information during the operation of the rotor.

[0015] The present invention also provides a method for online measuring the opening of a fan blade moving blade. The method is based on the above-mentioned device for online measuring the opening of a fan blade moving blade, and comprises: Step 1, respectively counting the blade tip passing signal of the opening sensor and the blade tip passing signal of the shaft sensor, and obtaining whether the blade opening is within the monitoring range by comparing the counting difference; Step 2: When the blade opening is within the monitoring range, the phase data of the blade opening sensor and the phase data of the shaft sensor are recorded cyclically for each cycle, and 16 full cycles are recorded continuously; Step 3, calculate the average phase of each blade opening sensor and the average phase of the shaft sensor within 16 full cycles, and make a difference according to the blades; Step 4: Compare and interpolate the phase difference of the blades with the phase difference and blade opening calibration data under normal working conditions to obtain the actual opening of each blade.

[0016] A further improvement of the present invention is that the phase difference and blade opening calibration data under normal working conditions are obtained by: After installing the sensors and key phase measurement points as required, and under the condition that the fan blade adjustment mechanism functions normally, adjust the fan blades to different openings and low speed operation, measure the phase difference between the opening sensor and the shaft sensor under different blade opening conditions, and establish the corresponding relationship between the fan blade opening and the sensor measured phase difference.

[0017] A further improvement of the present invention is that the method identifies the actual opening of the wind turbine blades by changing the phase difference between the blade tip passing signal monitored by the opening sensor and the blade tip passing signal monitored by the shaft sensor.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides an online measurement method and device for the opening of a fan blade rotor. By arranging two blade tip sensors axially in the blade rotation area, the passing phase of the top of the fan rotor blade is directly measured, and the angle of the fan rotor blade is calculated by the phase difference. Compared with the method of diagnosing the blade opening based on the aerodynamic data profile, the direct measurement method of the present invention has higher fault diagnosis accuracy and can locate the fault to a specific blade, and has higher stability. At the same time, the present invention can locate the fault point to a specific blade when diagnosing the asynchronous opening fault of the rotor blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Attached Figure 1 It is an overall schematic diagram of an implementation example of the present invention.

[0021] Attached Figure 2 It is a schematic diagram of the arrangement of blade tip sensors according to an embodiment of the present invention.

[0022] Attached Figure 3 It is a phase diagram of sensor arrangement of an implementation example of the present invention.

[0023] Attached Figure 4 It is a graph showing the relationship between blade opening and blade tip sensor signal.

[0024] Attached Figure 5 It is a flow chart of the blade opening conversion algorithm of the present invention.

[0025] Description of reference numerals: 1. Key phase sensor; 2. Opening sensor; 3. Rotating shaft sensor; 4. Blade opening adjustment rotating shaft; 5. Key phase measurement point; 6. Key phase calculation starting point; 7. Key phase calculation starting point layout range. DETAILED DESCRIPTION

[0026] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0030] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0031] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0032] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0033] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0034] Example 1 like Figures 1 to 3As shown, the present embodiment provides an online measuring device for the opening of a fan blade moving blade, comprising a key phase sensor 1, an opening sensor 2, a rotating shaft sensor 3 and a key phase measuring point 5; the key phase sensor 1 is installed at the fan coupling or the motor output shaft in a non-contact manner, and a key phase signal is obtained once every rotation; the opening sensor 2 and the rotating shaft sensor 3 are installed on the casing through the casing opening; the key phase measuring point 5 is arranged so that the key phase calculation starting point 6 is located within the angle range 7 formed by the leading edge of the blade and the previous blade opening adjustment rotating shaft 4 when the blade opening is minimum.

[0035] In this embodiment, if Figure 3 As shown, the key phase sensor 1 and the opening sensor 2 are arranged in the same phase, and the key phase measurement point 5 is arranged so that the key phase calculation starting point 6 is located within the angle range 7 formed by the leading edge of the blade and the previous blade opening adjustment rotating shaft 4 when the blade opening is minimum, so as to prevent the blade tip passing signal from exceeding the phase interval during the blade opening adjustment process, thereby causing blade encoding errors. When the key phase sensor 1 and the opening sensor 2 are arranged in the same phase, the temporal consistency of the two can be ensured, thereby avoiding confusion caused by phase difference during data processing. By setting the key phase calculation starting point 6 position within the angle range 7 formed by the leading edge of the blade and the previous blade opening adjustment rotating shaft 4 when the blade opening is minimum, it can be ensured that during the blade opening adjustment process, the blade tip passing signal is always within the expected phase interval.

[0036] In this embodiment, the key phase can be obtained by using a photoelectric sensor with reflective paper or an eddy current sensor with a key slot. When the photoelectric sensor is used with reflective paper to obtain the key phase, the reflective paper is pasted on the rotating part as a mark. When the rotating part rotates, the photoelectric sensor detects the position of the reflective paper by receiving and reflecting light. Each time the sensor passes the reflective paper, a pulse signal is triggered. This method is convenient for measuring the phase and is conducive to improving work efficiency. The photoelectric sensor has strong adaptability to the environment and can work in a variety of environments.

[0037] When the eddy current sensor is used with a keyway to obtain the key phase, a keyway is machined on the rotating part as a mark. The eddy current sensor generates a pulse signal by measuring the change in the distance between the probe and the measured rotor surface. When the rotating part rotates to the keyway position, the distance between the probe and the measured surface will change, thereby triggering a pulse signal. Using this method, the keyway marking is stable and reliable, not easily affected by the environment, and the eddy current sensor has high measurement accuracy and sensitivity.

[0038] The key phase sensor 1 cooperates with the key phase measuring point 5 to measure the rotation speed of the fan rotor and provide key phase information during the operation of the rotor.

[0039] In this embodiment, the opening sensor 2 is a blade tip sensor for recording the blade tip passing signal. The sensor type is an eddy current sensor, which is radially installed on the casing in the blade rotation plane. The axial position of the sensor centerline along the fan shaft is located in front of the blade opening adjustment rotating axis. The axial distance of the sensor axis is slightly larger than 3 times the diameter of the eddy current sensor, ensuring that the eddy current sensor obtains the largest possible blade opening measurement range under the condition of no mutual interference.

[0040] Among them, the blade tip sensor is a sensor used to detect the gap between the tip of the impeller or blade and the surrounding structure (such as the casing or inner wall) in the rotating machinery. The eddy current sensor, also known as the eddy current sensor or eddy current measurement sensor, is a sensor that uses the eddy current principle for measurement and detection. Its working principle is based on Faraday's law of electromagnetic induction and Lenz's law. When a block metal conductor is placed in a changing magnetic field or moves in a magnetic field to cut magnetic lines of force, a vortex-shaped induced current will be generated in the conductor. This current is called eddy current, and the above phenomenon is called eddy current effect. The eddy current sensor uses the reverse magnetic field generated by this eddy current to measure the relative position of the metal conductor being measured and the end face of the probe.

[0041] In this embodiment, the shaft sensor 3 is a blade tip sensor for recording blade tip passing signals. The sensor type is an eddy current sensor, which is radially mounted on the casing in the blade rotation plane. The axial position of the sensor centerline along the fan shaft is the same as the axial position of the blade opening adjustment rotation axis, ensuring that the blade tip phase angle monitored by the shaft sensor is basically consistent when the blade opening is adjusted. Figure 2 , Attachment Figure 4 As shown, in this embodiment, the opening sensor 2 and the shaft sensor 3 are arranged at the same phase angle, the opening sensor 2 receives the blade passing signal first, and the shaft sensor 3 receives the blade passing signal later.

[0042] Example 2 like Figure 5 As shown, this embodiment provides an online measurement method for the opening of a fan blade rotor blade, comprising: Step 1, respectively counting the blade tip passing signal of the opening sensor and the blade tip passing signal of the shaft sensor, and obtaining whether the blade opening is within the monitoring range by comparing the counting difference; Step 2: When the blade opening is within the monitoring range, the phase data of the blade opening sensor and the phase data of the shaft sensor are recorded cyclically for each cycle, and 16 full cycles are recorded continuously; Step 3, calculate the average phase of each blade opening sensor and the average phase of the shaft sensor within 16 full cycles, and make a difference according to the blades; Step 4: Compare and interpolate the phase difference of the blades with the phase difference and blade opening calibration data under normal working conditions to obtain the actual opening of each blade.

[0043] Example 3 like Figure 5 As shown, this embodiment provides an online measurement method for the opening of a fan blade rotor blade, comprising: Step 1, respectively counting the blade tip passing signal of the opening sensor and the blade tip passing signal of the shaft sensor, and obtaining whether the blade opening is within the monitoring range by comparing the counting difference; Step 2: When the blade opening is within the monitoring range, the phase data of the blade opening sensor and the phase data of the shaft sensor are recorded cyclically for each cycle, and 16 full cycles are recorded continuously; Step 3, calculate the average phase of each blade opening sensor and the average phase of the shaft sensor within 16 full cycles, and make a difference according to the blades; Step 4: Compare the phase difference of the blade with the phase difference under normal working condition. ΔΦ and blade opening O Calibration data Δ Φ 0 for comparison calculation, as shown in the following formula, to obtain the actual opening of each blade O r .

[0044]

[0045] In this embodiment, the phase difference and blade opening calibration data under normal working conditions involved in step 4 of the blade opening conversion algorithm of the present invention are obtained by the following method: After installing the sensors and key phase measuring points as required, adjust the fan blades to different openings when the fan blade adjustment mechanism functions normally. O Run at low speed and measure the phase difference between the opening sensor and the shaft sensor at different blade openings ΔΦ 0, establish the corresponding relationship between the fan blade opening percentage and the sensor measurement phase difference.

[0046] In this embodiment, if Figure 4 As shown, the blade opening conversion algorithm identifies the actual opening of the blade by changing the phase difference between the blade tip passing signal monitored by the opening sensor 2 and the blade tip passing signal monitored by the shaft sensor 3.

[0047] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0048] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An online measuring device for fan blade opening, characterized in that: It comprises a key phase sensor (1), an opening sensor (2), a shaft sensor (3) and a key phase measuring point (5); The key phase sensor (1) is installed at the fan coupling or the motor output shaft in a non-contact manner, and a key phase signal is obtained once every rotation; the opening sensor (2) and the shaft sensor (3) are installed on the casing through the casing opening; the key phase measurement point (5) is arranged so that the key phase calculation starting point (6) is located within the angle range (7) formed by the leading edge of the blade and the previous blade opening adjustment rotating axis (4) when the blade opening is minimum.

2. The online measuring device for fan blade opening according to claim 1 is characterized in that: The key phase sensor (1) and the opening sensor (2) are arranged in the same phase.

3. The online measuring device for fan blade opening according to claim 1 is characterized in that: The key phase is obtained through a photoelectric sensor combined with reflective paper.

4. The online measuring device for fan blade opening according to claim 1 is characterized in that: The key phase is obtained by using an eddy current sensor in combination with a keyway.

5. The online measuring device for fan blade opening according to claim 1 is characterized in that: The opening sensor (2) is a blade tip sensor for recording blade tip passing signals. The sensor type is an optical fiber sensor or an eddy current sensor. The sensor is radially mounted on the casing in the blade rotation plane. The axial position of the sensor centerline along the fan shaft is located in front of or behind the blade opening adjustment rotation axis. If the sensor arrangement space allows, the sensor should be arranged in front of the blade opening adjustment rotation axis.

6. The online measuring device for fan blade opening according to claim 1, characterized in that: The shaft sensor (3) is a blade tip sensor used to record blade tip passing signals. The sensor type is an optical fiber sensor or an eddy current sensor. It is radially mounted on the casing within the blade rotation plane. The axial position of the sensor centerline along the fan shaft is the same as the axial position of the blade opening adjustment rotation axis.

7. The online measuring device for fan blade opening according to claim 1 is characterized in that: The key phase sensor (1) cooperates with the key phase measuring point (5) to measure the rotation speed of the fan rotor and provide key phase information during the operation of the rotor.

8. A method for online measurement of fan blade opening, characterized in that: The method is based on an online measuring device for the opening of a fan blade according to any one of claims 1 to 7, comprising: Step 1, respectively counting the blade tip passing signal of the opening sensor and the blade tip passing signal of the shaft sensor, and obtaining whether the blade opening is within the monitoring range by comparing the counting difference; Step 2: When the blade opening is within the monitoring range, the phase data of the blade opening sensor and the phase data of the shaft sensor are recorded cyclically for each cycle, and 16 full cycles are recorded continuously; Step 3, calculate the average phase of each blade opening sensor and the average phase of the shaft sensor within 16 full cycles, and make a difference according to the blades; Step 4: Compare and interpolate the phase difference of the blades with the phase difference and blade opening calibration data under normal working conditions to obtain the actual opening of each blade.

9. The method for online measuring the opening of a fan blade according to claim 8, characterized in that: The phase difference and blade opening calibration data under normal working conditions are obtained by: After installing the sensors and key phase measurement points as required, and under the condition that the fan blade adjustment mechanism functions normally, adjust the fan blades to different openings and low speed operation, measure the phase difference between the opening sensor and the shaft sensor under different blade opening conditions, and establish the corresponding relationship between the fan blade opening and the sensor measured phase difference.

10. The method for online measuring the opening of a fan blade according to claim 8, characterized in that: The method identifies the actual opening of the wind turbine blades by changing the phase difference between a blade tip passing signal monitored by an opening sensor (2) and a blade tip passing signal monitored by a shaft sensor (3).

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