A wind power hydraulic special pipeline resonance type cleaning process

Abstract

A kind of wind power hydraulic pipeline resonance type cleaning process, comprising the following steps: connecting the pipeline to be cleaned into closed loop fluid circuit, outputting sinusoidal pressure pulse with phase difference of 180 degrees by two-end pressure pulse excitation device, exciting hydraulic fluid resonance in pipe, stripping the impurities attached to inner wall by fluid resonance effect, constructing finished product pipeline actual measurement database in advance, fitting inherent resonance frequency correlation trend curve with total length of pipeline as variable to obtain preliminary predicted inherent resonance frequency of pipeline to be measured;Combining the frequency offset caused by pipe diameter, wall thickness and bending to widen the sweep frequency interval, and then carrying out cleaning operation after determining the real fluid resonance frequency in the interval.The present application saves full-band scanning, shortens the sweep frequency debugging time, can efficiently clean the inner wall of pipeline, and improves the cleaning quality and processing efficiency of wind power hydraulic pipeline.

Description

Technical Field

[0001] This invention belongs to the field of wind power equipment manufacturing technology, specifically referring to a resonant cleaning process for wind power hydraulic pipelines. Background Technology

[0002] Hydraulic pipelines in wind turbines are critical components of the wind turbine hydraulic system. During the manufacturing process, metal shavings, rolling oil stains, and processing impurities can easily remain on the inner walls of the pipelines. These residues directly affect the reliability of the wind turbine hydraulic system's operation. Current methods for cleaning wind turbine hydraulic pipelines mostly involve immersion rinsing or high-pressure direct injection rinsing, relying on direct fluid impact to remove impurities from the inner walls. However, at locations with abrupt structural changes such as bends and joints, the fluid impact effect is easily diminished, resulting in limited cleaning effectiveness.

[0003] Existing cleaning processes often rely on increasing flushing pressure and extending flushing time to improve cleaning results. High-pressure fluids can easily cause impact damage to the inner wall of thin-walled pipes, while simply extending the operation time will reduce the efficiency of pipe production and processing. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a resonant cleaning process for wind power hydraulic pipelines, which at least partially solves the above problems.

[0005] A resonant cleaning process for hydraulic pipelines in wind power systems includes the following steps: Obtain the inherent resonant frequency of the pipeline filling system; Based on the preset frequency range and the kinematic viscosity of the cleaning fluid, the cleaning fluid with the corresponding kinematic viscosity is matched according to the frequency range to which the inherent resonant frequency of the pipeline filling system belongs. A closed-loop fluid circuit is established by connecting the inlet and outlet ends of the pipeline to be cleaned to a pressure pulse excitation device. The output frequency of the two pressure pulse excitation devices is consistent with the natural resonant frequency of the pipeline filling system. The phase difference of the output pulses at both ends is set to 180 degrees. The bidirectional anti-phase pulses form a stable standing wave field inside the pipe cavity to compensate for the energy loss of the resonant wave reflection at the abrupt change position of the pipeline structure. The closed-loop fluid circuit maintains a constant average base pressure and is superimposed with pressure pulsations that meet the pipeline resonance conditions to complete continuous resonance cleaning. Dry compressed air is used to purge and remove residual cleaning fluid from inside the pipeline.

[0006] Furthermore, for mass-produced pipelines, the inherent resonant frequency of the pipeline filling system is obtained by retrieving a pre-established database, which records the inherent resonant frequencies of the filling system of each specification of pipeline after pre-testing.

[0007] Furthermore, for the newly developed pipeline, a sinusoidal pressure frequency conversion excitation is applied to the liquid filling circulation loop, and the peak fluid pressure at the loop outlet is collected. Based on the variation characteristics of the pressure peak, the natural resonant frequency of the pipeline liquid filling system is determined. In this scheme, the excitation frequency corresponding to the maximum pressure peak is determined as the natural resonant frequency of the pipeline liquid filling system.

[0008] Furthermore, all historical measured data in the database were retrieved, and the correlation trend curve between the pipeline specifications and the inherent resonant frequency of the liquid filling system was fitted with the total pipeline length as a variable. The narrow frequency sweep interval was locked with the predicted resonant frequency as the center, and frequency conversion excitation testing was carried out only in this interval.

[0009] Furthermore, after completing the frequency conversion excitation test of each new pipeline, all specifications and parameters of the new product and the measured resonant frequency are simultaneously entered into the database, and the specification correlation curve is updated.

[0010] Furthermore, the preset frequency range includes a low-frequency range and a mid-frequency range. The low-frequency range is 5Hz-15Hz, and the mid-frequency range is 15Hz-30Hz. Different frequency ranges are matched with cleaning fluids of different kinematic viscosities.

[0011] Furthermore, under test conditions at 40℃, the kinematic viscosity of the pipeline with a natural resonant frequency in the low-frequency range was 4.0-4.5 mm. 2 Cleaning fluid per second; pipeline matching kinematic viscosity of 1.8-2.5 mm for natural resonant frequencies in the mid-frequency range. 2 / s of cleaning fluid.

[0012] Furthermore, the average base pressure of the closed-loop fluid circuit is set to 0.7-0.9 MPa, and the average base pressure is kept constant throughout the cleaning process.

[0013] Furthermore, a water-soluble thickener with a mass ratio of 0.25%-0.35% is added to the cleaning fluid corresponding to the low-frequency range to adjust the kinematic viscosity of the cleaning fluid to the matching range.

[0014] Furthermore, the continuous cleaning time of the pipeline under standing wave resonance conditions is set to 7-9 minutes.

[0015] The beneficial effects of this invention are as follows: This invention utilizes pressure pulse excitation at both ends to construct a standing wave field inside the pipe, and relies on the inherent resonant frequency of the pipeline filling system to match the corresponding kinematic viscosity of the cleaning fluid. It can effectively remove impurities from structurally abrupt locations such as bends and joints in the pipeline without relying on excessively high flushing pressure, reducing the risk of damage to thin-walled pipes by high-pressure fluids. The closed-loop circuit, combined with compressed air purging, achieves clean treatment of the inner wall of the pipeline, making it suitable for mass production of wind power hydraulic pipelines and ensuring the reliability of subsequent use of the pipes. Attached Figure Description

[0016] Figure 1 This is a flowchart of the resonant cleaning process for wind power hydraulic pipelines according to an embodiment of the present invention; Figure 2 This is a trend curve showing the relationship between pipeline specifications and inherent resonant frequency.

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] like Figure 1As shown in the embodiment of the present invention, a resonant cleaning process for wind power hydraulic pipelines is provided. During pipeline cleaning, the inherent resonant frequency of the pipeline filling system is first obtained. Based on the preset frequency range and the correspondence between the frequency range and the kinematic viscosity of the cleaning fluid, a cleaning fluid with the corresponding kinematic viscosity is matched according to the frequency range to which the inherent resonant frequency of the pipeline filling system belongs. The wind power hydraulic pipeline to be cleaned has an inlet end and an outlet end. Pressure pulse excitation devices are respectively connected to the inlet end and the outlet end of the pipeline. The pipeline body, the two pressure pulse excitation devices, and the external guide line connecting the pipeline together form a closed-loop fluid circuit. The medium can circulate within the entire system and will not be directly discharged to the outside. The pressure pulse excitation device is a fluid pulse generation unit that can output sinusoidal pressure pulses. The excitation frequency output range is 5-30Hz. The two devices can independently adjust the output pulse phase. The steady-state pressure of the fluid is maintained by the built-in pressure stabilizing unit of the device. The pressure pulsation is a fluctuation component superimposed on the steady-state pressure. The output frequency of the two pressure pulse excitation devices is consistent with the natural resonant frequency of the pipeline filling system. The phase difference of the output pulses at both ends is set to 180 degrees. The bidirectional anti-phase pulses are input into the pipeline cavity from both ends. The resonant pressure wave propagating inside the pipeline will be reflected when it encounters structural abrupt changes such as bends, joints, and diameter changes. The wave reflection will lose some of the wave energy. The bidirectional anti-phase input pulses can compensate for the energy loss caused by the reflection, thereby forming a stable standing wave field inside the pipeline cavity. The closed-loop fluid circuit maintains a constant average base pressure and superimposes pressure pulsations that meet the pipeline resonance conditions to complete continuous resonant cleaning. After the cleaning operation is completed, the circulation circuit is disconnected, and dry compressed air is used to purge and remove the residual cleaning fluid inside the pipeline. This operation method relies on the effect of the standing wave field inside the pipe to remove impurities from the inner wall without relying on ultra-high fluid impact pressure. It can remove impurities at structural abrupt changes such as bends and joints in the pipeline.

[0020] In some embodiments, for mass-produced pipelines, the inherent resonant frequency of the pipeline filling system is obtained by retrieving a pre-established database. The database records the inherent resonant frequencies of the filling systems of pipelines of various specifications that have been pre-tested. The database stores a one-to-one correspondence between the total length of the pipeline, the number of bends, the diameter, the wall thickness and the inherent resonant frequency. Table 1 is only a partial sample record selected from the database, not all of the samples used for fitting calculation. The inherent resonant frequency value of the corresponding pipeline stored in the database can be directly read and used in the subsequent cleaning process. This method eliminates the need for repeated frequency sweeping and measurement steps for each pipe, which is beneficial for improving the processing cycle of a single pipe under mass production conditions. In this embodiment, a wind power hydraulic special pipeline with a total length of 6m, 4 bends, a diameter of 16mm and a wall thickness of 2mm is selected for processing and cleaning. The same batch of mass-produced pipelines is processed in actual operation. The 21Hz inherent resonant frequency data corresponding to this model of pipeline is directly retrieved from the database and used directly for subsequent pulse excitation parameter setting. The measured sample data of this batch of pipes are shown in Table 1.

[0021] Table 1. Sample parameters of mass-produced pipelines

[0022] In some embodiments, for a brand-new prototype pipeline, a sinusoidal pressure frequency conversion excitation sweep is performed on the liquid filling circulation loop. The excitation frequency changes continuously, and the peak fluid pressure at the loop outlet is collected. When the excitation frequency approaches the inherent resonant frequency of the pipeline liquid filling system, the peak fluid pressure collected at the loop outlet reaches a maximum value. The excitation frequency corresponding to the maximum value of the pressure peak is determined as the inherent resonant frequency of the pipeline liquid filling system. Here, the inherent resonant frequency of the pipeline liquid filling system refers to the excitation frequency corresponding to the resonance of the fluid-pipeline coupling system after the cleaning fluid is filled into the pipeline. When the excitation frequency matches the inherent resonant frequency, the peak fluid pressure detected at the loop outlet will reach a significant maximum value. This is used as the basis for determining the frequency. This method can complete the calibration of the inherent resonant frequency of new pipelines without historical data.

[0023] The actual operation was conducted on a brand-new prototype wind power hydraulic pipeline with a total length of 7.5m, 3 bends, a diameter of 14mm, and a wall thickness of 1.8mm. The excitation frequency was gradually adjusted from 5Hz to 30Hz, and the peak pressure of the outlet fluid was collected. When the pressure peak reached its maximum value, the excitation frequency was read as 12Hz, and this value was taken as the natural resonant frequency of the prototype pipeline.

[0024] In some embodiments, all historical measured data from the database are retrieved, and a correlation trend curve between the pipeline specifications and the inherent resonant frequency of the fluid-filled system is fitted using the total pipeline length as a variable. This correlation trend curve characterizes the corresponding change relationship between the total pipeline length and the inherent resonant frequency after fluid filling. Under actual production conditions of wind power hydraulic pipelines, the pipeline diameter, wall thickness, and number of bends are generally positively correlated with the total pipeline length. The total pipeline length is the core parameter affecting the inherent resonant frequency of the fluid-filled system. Based on this core parameter, the preliminary predicted inherent resonant frequency of the new pipeline to be tested can be obtained. Since different pipeline diameters, wall thicknesses, and number of bends will cause a certain frequency shift, the frequency sweep range is appropriately widened after using this preliminary predicted inherent resonant frequency as the center before frequency conversion excitation testing is carried out. It is not necessary to perform scanning testing on the entire frequency range of 5-30Hz, thereby reducing the amount of data collected for frequency scanning and shortening the frequency sweep time.

[0025] In the actual operation, a brand-new prototype wind power hydraulic pipeline with a total length of 7.3m, 5 bends, a pipe diameter of 19mm, and a wall thickness of 2.1mm was tested. Based on the fitting of multiple sets of historical pipe data in the database, a correlation trend curve was obtained, and the resonant frequency of the new pipeline under test was predicted to be about 18Hz. Using this value as the center, and taking into account the differences in the number of bends, pipe diameter, and wall thickness of the pipeline under test, the frequency sweep interval was widened. The frequency conversion excitation test was only carried out within the processed frequency sweep interval to determine the true natural resonant frequency.

[0026] In some embodiments, after completing the frequency conversion excitation test of each new pipeline, all specifications and parameters of the new product and the measured resonant frequency are simultaneously entered into the database, the specification correlation curve is updated, and the database sample base is continuously enriched, so that the frequency prediction results of subsequent new pipelines are more in line with the actual working conditions and the prediction deviation is reduced. After the actual operation of a prototype pipeline with a total length of 8m, 5 bends, a pipe diameter of 20mm, and a wall thickness of 2.2mm is completed and tested, the total length of the pipeline, the number of bends, the pipe diameter, the wall thickness, and the measured natural resonant frequency of 19Hz are all entered into the database, and the existing specification correlation trend curve is updated and iterated.

[0027] In some embodiments, the preset frequency range includes a low-frequency range and a mid-frequency range. The low-frequency range is 5Hz≤f<15Hz, and the mid-frequency range is 15Hz≤f≤30Hz. Different frequency ranges are matched with cleaning fluids of different kinematic viscosities. Kinematic viscosity characterizes the magnitude of internal frictional resistance during fluid flow. The fluid damping requirements differ under different frequency resonance conditions. Adapting to fluids of different viscosities can ensure the effective transfer of standing wave field energy inside the pipeline and avoid excessive energy decay. In actual operation, the inherent resonant frequency of the pipeline is identified as 11Hz, which is classified as a low-frequency range, and a cleaning fluid suitable for the low-frequency range is selected for operation. The inherent resonant frequency of another pipeline is identified as 22Hz, which is classified as a mid-frequency range, and a cleaning fluid suitable for the mid-frequency range is selected for operation.

[0028] In some embodiments, under test conditions at 40°C, the kinematic viscosity of the pipeline with an inherent resonant frequency in the low-frequency range is 4.0-4.5 mm. 2 For cleaning fluid with a per-second viscosity, the kinematic viscosity of the pipeline matching the inherent resonant frequency in the mid-frequency range is 1.8-2.5 mm. 2 The cleaning fluid has a flow rate of / s. 40℃ is a common testing temperature for fluid parameters in the hydraulic industry. Limiting the testing temperature eliminates interference from temperature changes on kinematic viscosity parameters, ensuring the cleaning fluid characteristics match the resonant operating conditions. During operation, a temperature control device can be used to maintain the cleaning fluid temperature stable at 40℃. In actual operating environments, the cleaning fluid temperature is maintained at 40℃. For a low-frequency pipeline with an inherent resonant frequency of 12Hz, a total length of 7.5m, 3 bends, a pipe diameter of 14mm, and a wall thickness of 1.8mm, a 4.2mm diameter pipe is selected. 2 / s kinematic viscosity cleaning fluid; for a medium-frequency pipeline with an inherent resonant frequency of 18Hz, a total length of 7.3m, 5 bends, a pipe diameter of 19mm, and a wall thickness of 2.1mm, a 2.1mm diameter fluid is selected. 2 / s kinematic viscosity cleaning fluid; the parameters of the cleaning fluid in different frequency ranges are shown in Table 2.

[0029] Table 2 Cleaning fluid parameters for different frequency ranges (40℃)

[0030] In some embodiments, the average base pressure of the closed-loop fluid circuit is set to 0.7-0.9 MPa. The average base pressure is kept constant throughout the cleaning process. The circuit only adds the pressure pulsation required for resonance on top of the constant average base pressure. The average base pressure is the steady-state pressure of the closed-loop fluid circuit excluding the pulsation component. Maintaining a stable average base pressure can avoid stress impact on pipe welds and thin-walled locations caused by large fluctuations in overall pressure, and prevent fatigue damage to pipe fittings. In actual operation, for a wind power hydraulic pipeline with a total length of 6m, 4 bends, a pipe diameter of 16mm, and a wall thickness of 2mm, the average base pressure of the closed-loop fluid circuit is set to 0.8 MPa. The average base pressure is kept constant throughout the cleaning process, and the pressure pulsation is added on top of this to complete the resonance cleaning.

[0031] In some embodiments, a water-soluble thickener at a mass ratio of 0.25%-0.35% is added to the cleaning fluid corresponding to the low-frequency range to adjust the kinematic viscosity of the cleaning fluid to the matching range. The water-soluble thickener can increase the kinematic viscosity of the fluid in the water-based cleaning system, increase fluid damping, adapt to the resonant cleaning conditions of the pipeline in the low-frequency range, and reduce the impact of the fluid on the thin-walled pipe wall during the standing wave process. In actual operation, for the cleaning fluid used in the low-frequency range pipeline with an inherent resonant frequency of 12Hz, a total length of 7.5m, 3 bends, a pipe diameter of 14mm, and a wall thickness of 1.8mm, a water-soluble thickener at a mass ratio of 0.30% is added to adjust the kinematic viscosity of the cleaning fluid to 4.3mm. 2 / s, meeting the requirements for low-frequency operation.

[0032] In some embodiments, the continuous cleaning time of the pipeline under standing wave resonance condition is set to 7-9 minutes. Within this time range, the standing wave field inside the pipeline can fully act on various positions of the pipeline inner wall, so that impurities such as metal chips and rolling oil stains are peeled off and removed from the pipeline wall under the repeated disturbance of the resonant pressure wave. At the same time, it avoids the waste of production cycle caused by ineffective long-term operation. If the cleaning time is too short, the impurities at the bends and joints will not be peeled off sufficiently. If the time is too long, the processing efficiency will be reduced. In actual operation, for a wind power hydraulic pipeline with a total length of 6m, 4 bends, a pipe diameter of 16mm, and a wall thickness of 2mm, the continuous cleaning time under standing wave resonance condition is set to 8 minutes to complete the cleaning operation of impurities on the inner wall of the wind power hydraulic pipeline.

[0033] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A resonant cleaning process for hydraulic pipelines in wind power applications, characterized in that: Obtain the inherent resonant frequency of the pipeline filling system; Based on the preset frequency range and the kinematic viscosity of the cleaning fluid, the cleaning fluid with the corresponding kinematic viscosity is matched according to the frequency range to which the inherent resonant frequency of the pipeline filling system belongs. A closed-loop fluid circuit is established by connecting the inlet and outlet ends of the pipeline to be cleaned to a pressure pulse excitation device. The output frequency of the two pressure pulse excitation devices is consistent with the natural resonant frequency of the pipeline filling system. The phase difference of the output pulses at both ends is set to 180 degrees. The bidirectional anti-phase pulses form a stable standing wave field inside the pipe cavity to compensate for the energy loss of the resonant wave reflection at the abrupt change position of the pipeline structure. The closed-loop fluid circuit maintains a constant average base pressure and is superimposed with pressure pulsations that meet the pipeline resonance conditions to complete continuous resonance cleaning. Dry compressed air is used to purge and remove residual cleaning fluid from inside the pipeline.

2. The resonant cleaning process for wind power hydraulic pipelines according to claim 1, characterized in that: For mass-produced pipelines, the inherent resonant frequency of the pipeline filling system is obtained by retrieving a pre-established database, which records the inherent resonant frequencies of the filling system of each pipeline specification that have been pre-tested.

3. The resonant cleaning process for wind power hydraulic pipelines according to claim 1, characterized in that: For the newly developed pipeline, a sinusoidal pressure frequency conversion excitation is applied to the liquid filling circulation loop, the peak fluid pressure at the loop outlet is collected, and the natural resonant frequency of the pipeline liquid filling system is determined based on the variation characteristics of the pressure peak.

4. The resonant cleaning process for wind power hydraulic pipelines according to claim 3, characterized in that: All historical measured data in the database were retrieved, and the correlation trend curve between the pipeline specifications and the inherent resonant frequency of the liquid filling system was fitted with the total pipeline length as a variable. With the predicted resonant frequency as the center, a narrow frequency sweep interval was locked, and frequency conversion excitation testing was carried out only in this interval.

5. The resonant cleaning process for wind power hydraulic pipelines according to claim 4, characterized in that: After completing the frequency conversion excitation test of each new pipeline, all specifications and measured resonant frequencies of the new product are simultaneously entered into the database, and the specification correlation curves are updated.

6. The resonant cleaning process for wind power hydraulic pipelines according to claim 1, characterized in that: The preset frequency range includes a low-frequency range and a mid-frequency range. The low-frequency range is 5Hz-15Hz, and the mid-frequency range is 15Hz-30Hz. Different frequency ranges are matched with cleaning fluids of different kinematic viscosities.

7. The resonant cleaning process for wind power hydraulic pipelines according to claim 6, characterized in that: Under test conditions of 40℃, the kinematic viscosity of the pipeline with a natural resonant frequency in the low-frequency range is 4.0-4.5 mm. 2 Cleaning fluid per second; pipeline matching kinematic viscosity of 1.8-2.5 mm for natural resonant frequencies in the mid-frequency range. 2 / s of cleaning fluid.

8. The resonant cleaning process for wind power hydraulic pipelines according to claim 1, characterized in that: The constant average base pressure of the closed-loop fluid circuit is set to 0.7-0.9 MPa, and the average base pressure is kept constant throughout the cleaning process.

9. The resonant cleaning process for wind power hydraulic pipelines according to claim 7, characterized in that: Add 0.25%-0.35% by mass of a water-soluble thickener to the cleaning fluid corresponding to the low-frequency range to adjust the kinematic viscosity of the cleaning fluid to the matching range.

10. The resonant cleaning process for wind power hydraulic pipelines according to claim 1, characterized in that: The continuous cleaning time of the pipeline under standing wave resonance conditions is set to 7-9 minutes.

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