Method and system for quickly removing frozen covering layer based on infrared mechanism

Abstract

The invention relates to the technical field of wind power generation blade infrared icebreaking, in particular to a method and system for rapidly removing a frozen covering layer based on an infrared mechanism, and the method specifically comprises the steps: S1, configuring at least one infrared transmitting device at a fixed point, and enabling the infrared transmitting device to irradiate the front edge of a downwards inclined wind power blade; the at least one infrared emitting device is used for emitting expanded light beams; and S3, infrared light with rated power density is irradiated to the front edge of the wind power blade, so that an interface water film is formed between the transparent ice layer and the surface of the blade, and the ice layer falls off from the blade. According to the method, at least one piece of beam-expanded infrared light is adopted, the emitted infrared light is expanded to form large-area light spots to irradiate the blade on the basis of infrared radiation in the rated power density interval, and when the blade coated with ice on the surface is continuously irradiated by the infrared radiation, ice, tightly attached to the surface of the blade, in an ice layer can be rapidly melted into an interface water film; the friction force between the blade and the ice layer is greatly reduced due to the water film.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared ice-breaking for wind power blades, and particularly relates to a method and a de-icing system for quickly removing a frozen covering layer based on an infrared mechanism. Background Art

[0002] It is extremely easy for a frozen covering layer to form on the surface of the blades of a wind turbine in high-humidity areas. Due to weather reasons, rime, glaze, mixed glaze, etc. adhere to the blades, increasing the weight of the blades, changing the shape, forming an unbalanced load, reducing the power generation of the wind turbine, causing damage to the blades, and affecting the power generation efficiency and service life of the wind turbine; when the blades rotate, ice throwing will also pose a safety hazard to nearby personnel. The current mainstream blade de-icing solutions in the industry are electric heating de-icing, gas heating de-icing, and coating anti-icing technologies. These solutions all have low maturity and may damage the blades, and cannot meet the use requirements. Therefore, a de-icing method based on an infrared mechanism has gradually emerged, but there are still the following defects:

[0003] First, some current de-icing technologies based on an infrared mechanism adopt the form of a focused beam. The beam is focused to the centimeter level, mainly used to completely melt the ice layer at the irradiation position, and cannot deal with a large range of ice layers. Even, it may cause damage to the blades; if directly converted by multiple beam arrangements, a large number of laser beams are required under the same area, which is difficult to control, and the spot uniformity cannot be guaranteed.

[0004] Second, another de-icing method based on an infrared mechanism uses a beam to scan the ice-covered layer to break the ice layer; however, under cold weather conditions, after the irradiation light source in a local area is removed, the ice layer will re-freeze in a very short time, and the ice-breaking effect is not ideal, so long-time irradiation of the light source is required. Summary of the Invention

[0005] The object of the present invention is to provide a method and a de-icing system for quickly removing a frozen covering layer based on an infrared mechanism to solve the problem of easy re-freezing of the frozen covering layer in traditional de-icing methods, and further solve the problems of low de-icing efficiency and easy damage to wind turbine blades caused by the light source.

[0006] The technical solution of the present invention is: A method for quickly removing a frozen covering layer based on an infrared mechanism, comprising:

[0007] S1. Fix at least one infrared emission device, and the infrared emission device is used for irradiating the leading edge of the downward-sloping wind turbine blade;

[0008] S2. Determine the irradiation parameters of the infrared emission device based on the thickness of the frozen covering layer. The irradiation parameters include spot area, power density, and irradiation time. At least one of the infrared emission devices is used to emit a diverging beam, and the spot area irradiated per unit centimeter thickness of the frozen covering layer is not less than 0.55 m 2 ;

[0009] S3. Irradiate the leading edge of the wind turbine blade with infrared light having a rated power density, and finally form an interfacial water film between the frozen covering layer and the surface of the wind turbine blade. When the gravity of the frozen covering layer is greater than the sum of the friction force and the stress, the frozen covering layer falls off the blade.

[0010] Preferably, at least two groups of the infrared emission devices are configured, including a first infrared emission part and a second infrared emission part. The first infrared emission part forms a first spot area, and the second infrared emission part forms a second spot area. There is an overlap between the first spot area and the second spot area.

[0011] Preferably, the first infrared emission part is used to emit a diverging beam, and the second infrared emission part is used to emit a converging beam.

[0012] Preferably, in step S2, the second infrared emission part emits a converging beam and projects it onto the leading edge of the wind turbine blade to obtain the thickness of the frozen covering layer at the corresponding position. Based on the thickness of the frozen covering layer, determine the spot area of the first infrared emission part, and emit a diverging beam and project it onto the leading edge of the wind turbine blade so that the first spot area covers the second spot area.

[0013] Preferably, the first infrared emission part moves from the root to the tip along the length direction of the wind turbine blade at a rated step size;

[0014] When the first infrared emission part is continuously irradiating, the converging beam emitted by the second infrared emission part reciprocates in the first spot area along the direction perpendicular to the length direction of the wind turbine blade.

[0015] Preferably, in any ice-breaking area of the wind turbine blade corresponding to the first spot area, the irradiation duration of the second infrared emission part is not greater than that of the first infrared emission part. Furthermore, the second infrared emission part withdraws from the corresponding ice-breaking area of the blade earlier than the first infrared emission part and advances one step size from the root to the tip along the length direction of the wind turbine blade.

[0016] Preferably, the second spot area is located at one end of the first spot area far from the root of the wind turbine blade.

[0017] Preferably, both the first infrared emission part and the second infrared emission part are used to emit diverging beams.

[0018] Preferably, both the first infrared emission part and the second infrared emission part move alternately from the root to the tip of the wind turbine blade along the length direction of the wind turbine blade at a rated step length.

[0019] Preferably, the power density of the infrared emission device for emitting an expanded light beam is 1 kW / m 2 ~10 kW / m 2 .

[0020] Preferably, the beam wavelength of the infrared emission device for emitting an expanded light beam is 750 nm to 860 nm; the beam wavelength of the infrared emission device for emitting a focused light beam is 1065 nm to 1940 nm.

[0021] Preferably, the incident angle of the light beam emitted by the infrared emission device is 75° to 105°.

[0022] An ice-covered layer removal system for the method of rapidly removing an ice-covered layer based on an infrared mechanism as described above.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] (1) This application uses at least one expanded infrared light. Based on the infrared radiation within the rated power density range, the emitted infrared light is expanded to form a large-area light spot and irradiated on the wind turbine blade. When the wind turbine blade with ice on its surface is continuously irradiated by the infrared radiation, no re-icing phenomenon will occur in the large-area region. The ice closely attached to the blade surface inside the ice layer will quickly melt into interfacial water, forming a "water film". This water film causes a significant reduction in the friction force between the blade and the ice layer. At the same time, the ice layer within the continuously irradiated area of the infrared radiation will also undergo structural splitting due to uneven internal thermal stress. When the gravity of the ice layer is greater than the sum of the friction force and the remaining stresses, the ice layer will quickly break and fall off.

[0025] (2) Under actual environmental conditions, especially when the ice layer is relatively thick, even if an interfacial water film is formed, the ice layer is not easily broken, and thus cannot break and fall off. This application combines a focused light beam to accelerate the fracture of the ice layer, thereby achieving rapid shedding of the ice layer. When the first infrared emission part is continuously irradiating, since the area of the second light spot region is small, the focused light beam emitted by the second infrared emission part reciprocates in the first light spot region along the direction perpendicular to the length direction of the wind turbine blade. At this time, due to the continuous irradiation of the first infrared emission part, no re-icing phenomenon will occur in the area traversed by the second infrared emission part after the light beam is removed. At the same time, the focused light beam reaches the ice-breaking area of the blade first, measures the thickness of the ice layer based on the infrared ranging principle, and thus facilitates the adjustment of the irradiation parameters of the expanded light beam.

[0026] (3) The present application also provides a method for ice breaking by combining two sets of expanded light beams. Both the first light spot area and the second light spot area have a distribution of beam energy, so that the overlapping part can achieve energy superposition, accelerate the fracture of the ice layer, and further improve the ice breaking efficiency. Description of the Drawings

[0027] The present invention will be further described below in conjunction with the drawings and embodiments:

[0028] Figure 1 It is a distribution diagram of the wind turbine blade and the infrared emission device in the actual application scenario in Embodiment 1 of the present invention;

[0029] Figure 2 It is the curve of the temperature rise of the blade surface over time when the direct radiation power density of the present invention is 1 kW / m 2 ;

[0030] Figure 3 It is the curve of the temperature rise of the blade surface over time when the direct radiation power density of the present invention is 5 kW / m 2 ;

[0031] Figure 4 It is the curve of the temperature rise of the blade surface over time when the direct radiation power density of the present invention is 10 kW / m 2 ;

[0032] Figure 5 It is a distribution diagram of the wind turbine blade and the infrared emission device in the actual application scenario in Embodiment 2 of the present invention. Detailed Embodiments

[0033] The content of the present invention will be further described in detail below in conjunction with specific embodiments:

[0034] For ease of understanding, the application scenario of the present application is first described. In high-humidity cold regions, glaze, rime, or a combined mixed glaze phenomenon, collectively referred to as a frozen covering layer, is likely to occur. Among them, glaze is a glassy transparent or dull ice covering layer formed on the surface of an object; rime is a milky white ice crystal deposit formed when water vapor in the air directly sublimates or supercooled fog droplets directly freeze on an object. The present application is used to remove the frozen covering layer on the blades of a wind turbine, avoiding an increase in blade weight, a change in shape, and the formation of an unbalanced load, and thus avoiding potential safety hazards.

[0035] Embodiment 1

[0036] The present application provides a method for quickly removing a frozen covering layer based on the infrared mechanism, which is mainly as follows:

[0037] The first step is to configure an infrared emission device;

[0038] As Figure 1 shown, two infrared emission devices are fixedly arranged near the wind turbine blade 100 of a wind turbine generator, including a first infrared emission part 200 and a second infrared emission part 300; the first infrared emission part 200 is used for emitting a diverging light beam, and the second infrared emission part 300 is used for emitting a converging light beam.

[0039] Due to the collision of supercooled water droplets and the influence of air flow during the operation of the wind turbine blade in cold weather, the windward surface at the leading edge is more likely to freeze, and the frozen covering layer is thicker; when the ambient temperature is lower than 0 °C, the supercooled water droplets in the air collide with the surface of the wind power blade, resulting in the destruction of the internal balance of the supercooled water droplets and a higher freezing temperature, and they condense into ice on the blade surface. The windward surface of the leading edge of the wind power blade is more likely to collide with supercooled water droplets, so the icing in this area is more serious. At the same time, the windward surface directly faces the air flow, and the supercooled water droplets in the air flow are more likely to be carried to the windward surface of the blade and adhere to freeze. While on the leeward surface, due to the relatively stable air flow, the contact opportunity with water droplets is less, and the amount of ice accretion is relatively small. Therefore, as combined with Figure 1 shown, the two infrared emission devices are used to irradiate the leading edge of the wind turbine blade that is inclined downward in the stationary state, and the incident angle α of the light beam emitted by the infrared emission device is 75° to 105°, and this incident angle is defined as the included angle between the center line of the light beam and the length direction of the wind turbine blade.

[0040] Step 2, determine the irradiation parameters of the infrared emission device;

[0041] In this embodiment, the first infrared emission part is used to irradiate to form a first light spot area on the wind turbine blade, and the second infrared emission part is used to irradiate to form a second light spot area on the wind turbine blade; in the de-icing scenario, the first light spot area and the second light spot area will overlap after being irradiated on the wind turbine blade.

[0042] a. During the de-icing process, regarding the light beam wavelength of the infrared emission device:

[0043] The light beam wavelength of the first infrared emission part 200 for emitting a diverging light beam is 750 nm to 860 nm. In order to ensure that the infrared light can effectively penetrate clouds and ice layers and be absorbed by the target surface medium at the same time, the infrared light needs to meet the following conditions during design: First, cloud penetration ability: Infrared rays have a strong ability to penetrate clouds and can maintain a good transmission effect under bad weather conditions; Second, ice layer penetration ability: Select infrared light with a shorter wavelength, which has higher energy and can more effectively penetrate the ice layer and achieve deep ice layer penetration; Third, ice layer absorption characteristics: The ice layer has a high absorption rate for infrared rays, which helps to improve the heating efficiency; Fourth, surface medium absorption: Most surface media have good absorption performance for infrared radiation, which helps to enhance the heating effect.

[0044] The beam wavelength of the second infrared emission part 300 for emitting a convergent beam is 1065 nm to 1940 nm. In this embodiment, the convergent beam needs to meet the following requirements: a. Measure the thickness of the frozen covering layer. Based on the time difference between the emission and reflection reception of the infrared convergent beam, calculate the thickness of the frozen covering layer; b. Accelerate the fracture of the ice layer. Still based on the absorption rate of the ice layer to infrared light, the area irradiated by the second infrared emission part can be accelerated to melt and fracture.

[0045] b. Regarding the spot area of the divergent beam emitted by the first infrared emission part 200;

[0046] In this embodiment, the spot area is positively correlated with the thickness of the frozen covering layer, and the spot area irradiated corresponding to each unit centimeter thickness of the frozen covering layer is not less than 0.55 m 2 .

[0047] Specifically, according to the ice-covered blade shear strength of 0.5 MPa and the ice-covered density of 900 kg / m 3 , when the ice thickness is 1 cm, the ice layer can withstand a shear force of no more than 50 N, that is, 5 kg of ice, which is equivalent to about 0.55 m 2 of the ice-covered area.

[0048] To ensure that there is sufficient spot area on the frozen covering layer, in this embodiment, the infrared light emitted by the infrared emission device is conducted through an optical fiber and homogenized, shaped, and beam-expanded through an optical device. Among them, homogenization and shaping are to make the irradiation power distribution in the spot more uniform, reduce the control difficulty, and increase the controllability of the system. The purpose of beam expansion is to make the spot area larger, so as to cope with the frozen covering layer in a larger range, which is completely different from the traditional focused de-icing technology that focuses the beam to the centimeter level and melts all the ice layers in the irradiation area.

[0049] c. Regarding the power density of the divergent beam emitted by the first infrared emission part 200:

[0050] In order to form an interfacial water film between the transparent ice layer and the wind turbine blade, the heating speed at the interface needs to be greater than the heat diffusion speed. In the simulation test at an ambient temperature of -20 °C, when the power density is lower than 1 kW / m 2 , the interface heating speed is lower than the heat diffusion speed, and it is difficult to form a water film at the ice-covered interface. In the simulation test at an ambient temperature of -10 °C, when the power density is higher than 10 kW / m 2 , it reaches the maximum temperature for the safe operation of the blade. Therefore, in this application, the power density is set to 1 kW / m 2 ~10 kW / m 2 .

[0051] Theoretically speaking, when the power density meets the minimum requirements and the energy consumption of the infrared emission device is not considered, the higher the power density, the better the de-icing effect. However, in this application, since the infrared light irradiated by the first infrared emission part forms a large-area light spot after beam expansion, and the ice layer on the surface of the wind turbine blade is not fully covered, it may exist locally or intermittently on the wind turbine blade. Therefore, when the infrared light irradiates the wind turbine blade, there are local light spots irradiating on the frozen covering layer and local light spots irradiating on the blade. When the infrared light directly irradiates the wind turbine blade, it is necessary to control the temperature rise of the wind turbine blade to avoid damage to the wind turbine blade. Therefore, it is necessary to control the power density, that is, the power density is not the larger the better.

[0052] In actual application scenarios, the external environmental conditions will also affect the temperature rise of the wind turbine blade surface. For example, the wind speed will accelerate the convection due to its existence and slow down the temperature rise of the blade surface. Therefore, the upper limit of the power density needs to be considered comprehensively in combination with the wind speed.

[0053] In a low-temperature chamber set at a constant temperature of -10 °C, place the blade section sample, create an air flow with a wind speed of about 3 m / s on the blade surface, and irradiate it with infrared radiation of 1 kW / m 2 , 5 kW / m 2 , 10 kW / m 2 respectively, and use an infrared thermometer to measure the highest temperature of the irradiated surface of the blade.

[0054] Combined with Figure 2 , Figure 3 , Figure 4 shown, as time changes, the surface of the wind turbine blade gradually warms up. At an ambient temperature of -10 °C and a direct power density of 10 kW / m 2 , in the case of a wind speed lower than 3 m / s, the highest temperature on the surface of the wind turbine blade reaches 70 °C within 5 minutes of continuous irradiation, that is, the maximum safe operating temperature of the wind turbine blade. Therefore, in the range of power density from 1 kW / m 2 to 10 kW / m 2 , set the continuous irradiation time to be less than 5 minutes to avoid problems of blade damage, and at the same time, it is necessary to ensure the working efficiency, and the continuous irradiation time cannot be too long.

[0055] d. Regarding the spot area and power density of the convergent beam emitted by the second infrared emission part:

[0056] Since the convergent beam emitted by the second infrared emission part is used to measure the thickness of the frozen covering layer and accelerate the fracture of the ice layer, a centimeter-level spot area is adopted, generally controlled between 5 and 25 cm 2 . The convergent beam is used to form an energy overlap with the expanded beam. Therefore, the power density can also be controlled between 1 kW / m 2 and 10 kW / m2 within the range of.

[0057] e. Regarding the irradiation time of the infrared emission device;

[0058] Referring to the above slicing experiment and combining with the attached Figure 4 It can be known that at an ambient temperature of -10°C and a direct irradiation power density of 10 kW / m 2 , in the case of a wind speed lower than 3 m / s, the highest temperature on the surface of the wind turbine blade reaches 70°C within 5 minutes of continuous irradiation. After that, for irradiation times exceeding 5 minutes, the temperature on the surface of the wind turbine blade will continue to rise. Therefore, in this application, the irradiation time of the infrared emission device is set not to exceed 5 minutes.

[0059] To sum up, the spot area, power density, and irradiation time will directly affect the removal efficiency of the frozen covering layer. In this embodiment, the power density and irradiation time are set as fixed values. For example: the power density is 6 kW / m 2 , and the irradiation time is 3 minutes; based on the thickness of the frozen covering layer obtained, the size of the spot area is adjusted. The spot area is positively correlated with the thickness of the frozen covering layer, and a mapping relationship between the two is established. Furthermore, under the condition of a constant power density and irradiation time, by adjusting the size of the spot area, the removal of frozen covering layers with different thicknesses is achieved. It should also be noted that since there needs to be an effective overlap between the subsequent first spot area and the second spot area, and they need to move at a rated step size, in this embodiment, the first infrared emission part is used to emit a rectangular light beam, which has a "length" set along the length direction of the wind turbine blade and a "width" perpendicular to the length direction of the wind turbine blade. The first spot area always moves at a rated step size along the "length" direction. Therefore, when adjusting the spot area, the width of the first spot area can be directly adjusted.

[0060] The third step, the infrared emission device starts irradiation;

[0061] Irradiate the infrared light with a rated power density onto the wind turbine blade and move along a preset running track; finally, an interfacial water film is formed between the frozen covering layer and the surface of the wind turbine blade. When the gravity of the frozen covering layer is greater than the sum of the frictional force and the stress, the frozen covering layer falls off the blade.

[0062] Specifically, during the initial irradiation, the second infrared emission part first emits a converging beam and projects it onto the leading edge near the root of the wind turbine blade to obtain the thickness of the frozen covering layer at the corresponding position of the converging beam. Based on the thickness of the frozen covering layer, the spot area of the first infrared emission part is determined, and a diverging beam is emitted and projected onto the leading edge of the wind turbine blade so that the first spot area covers the second spot area. When the first spot area coincides with the second spot area, the second spot area is located at one end of the first spot area that is far from the root of the wind turbine blade. In the ice removal scenario, the wind turbine blade irradiated by the infrared emission device tilts downward. Based on the water film formed by continuous irradiation of the first spot area and the ice layer fracture formed by overlapping irradiation of the first spot area and the second spot area, the shedding of the tilted ice layer can be accelerated. Since the second spot area is located at one end of the first spot area that is far from the root of the wind turbine blade, that is, the fracture occurs as much as possible below the frozen covering layer corresponding to the first spot area, and thus the ice layer shedding can be achieved over a larger area.

[0063] Since the first infrared emission part and the second infrared emission part irradiate the root position of the blade in the initial state, the subsequent specific movement trajectories are as follows:

[0064] The first infrared emission part moves from the root to the tip along the length direction of the wind turbine blade at a rated step size; when the first infrared emission part continuously irradiates, the converging beam emitted by the second infrared emission part reciprocates in the first spot area along the direction perpendicular to the length direction of the wind turbine blade. In any ice-breaking area of the wind turbine blade corresponding to the first spot area, the irradiation duration of the second infrared emission part is not greater than that of the first infrared emission part. Thus, the second infrared emission part withdraws from the corresponding ice-breaking area of the blade earlier than the first infrared emission part and advances one step along the length direction of the wind turbine blade to obtain the thickness of the ice layer in the next ice-breaking area to be processed in advance.

[0065] In the actual wind power generation scenario, the wind turbine blade faces complex and variable environmental conditions, and the existence form of the frozen covering layer shows diversity. First of all, the thickness distribution of the frozen covering layer does not show a simple rule of gradually increasing from the blade root to the tip. In an ideal theoretical model, it is assumed that the ice layer thickness gradually increases as the blade extends from the root to the tip. However, in reality, due to the combined influence of various factors such as wind force, humidity, and temperature, the distribution of the ice layer thickness is irregular. Secondly, the coverage area of the frozen covering layer is not completely continuous. In actual observations, it is often seen that the ice layer on the blade surface shows discontinuous distribution forms such as patchy and strip-shaped. In addition, factors such as the material and roughness of the blade surface also affect the adhesion and distribution of the ice layer, making the coverage of the ice layer on the blade surface uneven.

[0066] When the second infrared emission unit emits a convergent light beam onto the frozen covering layer, due to the diversity of the forms of the frozen covering layer, the convergent light beam may directly irradiate the wind turbine blade without the frozen covering layer attached. At this time, the thickness of the frozen covering layer cannot be obtained. Therefore, it is set that the first infrared emission device emits a divergent light beam with a minimum spot area (0.55 m 2 ) onto the wind turbine blade, and the second infrared emission device turns off the irradiation. By emitting a divergent light beam with a minimum spot area, more extensive detection and heating treatment can be performed on the surface of the wind turbine blade without wasting too much energy.

[0067] During the above operation process, since the first infrared emission unit emits a divergent light beam, forming a large-area spot irradiating on the wind turbine blade, when the wind turbine blade with ice on its surface is continuously irradiated by infrared radiation, there will be no re-icing phenomenon in the large-area region. The ice closely attached to the blade surface inside the ice layer will quickly melt into interfacial water, forming a "water film"; the laser beam emitted by the second infrared emission unit reciprocates in the first spot region along the direction perpendicular to the length of the wind turbine blade. At this time, due to the continuous irradiation of the first infrared emission unit, there will be no re-icing phenomenon in the area traversed by the second infrared emission unit after the light beam is removed.

[0068] Embodiment 2

[0069] The first step is to configure the infrared emission device;

[0070] As shown in Figure 5 , two infrared emission devices are fixedly configured near the wind turbine blade 100 of the wind power generation unit, including the first infrared emission unit 200 and the second infrared emission unit 300; both the first infrared emission unit 200 and the second infrared emission unit 300 are used to emit divergent light beams. In this embodiment, the two infrared emission devices are still used to irradiate the leading edge of the downward-sloping wind turbine blade, and the incident angle α of the light beam emitted by the infrared emission device is 75° - 105°.

[0071] The second step is to determine the irradiation parameters of the infrared emission device;

[0072] In this embodiment, since both the first infrared emission unit 200 and the second infrared emission unit 300 are used to emit divergent light beams, it can be defined that they have the same irradiation parameters.

[0073] Among them, the beam wavelengths of the first infrared emission unit and the second infrared emission unit are 750 nm - 860 nm;

[0074] The power densities of the first infrared emission unit and the second infrared emission unit are 1 kW / m 2 -10 kW / m 2 ;

[0075] The spot areas of the first infrared emission part and the second infrared emission part are not less than 0.55 m 2 ;

[0076] The continuous irradiation time of the first infrared emission part and the second infrared emission part is 3 min.

[0077] Step 3: The infrared emission device starts irradiation;

[0078] Irradiate the wind turbine blade with infrared light having a rated power density and move along a preset operation trajectory; finally, an interfacial water film is formed between the frozen covering layer and the blade surface. When the gravity of the frozen covering layer is greater than the sum of the frictional force and the stress, the frozen covering layer falls off the blade. In this embodiment, both the first infrared emission part and the second infrared emission part move alternately along the length direction of the wind turbine blade from the root to the tip at a rated step length. The overlapping part of the first spot area and the second spot area is used to accelerate the fracture of the ice layer, and thus accelerate the shedding of the inclined ice layer.

[0079] Specifically, first, the first infrared emission part emits a diverging beam and irradiates it on the root of the wind turbine blade to form a first spot area on the leading edge of the wind turbine blade. The second emission part moves a rated length L from the blade root to the blade tip relative to the first emission part and emits a diverging beam, thereby forming a second spot area on the leading edge of the wind turbine blade, and there should be an overlap between the first spot area and the second spot area; after the first infrared emission part irradiates for 3 min, the first infrared emission part moves from the blade root to the blade tip at a rated step length of 2L and continues to irradiate; after the second infrared emission part irradiates for 3 min, the second infrared emission part moves from the blade root to the blade tip at a rated step length of 2L, and so on in a cycle, so that the first infrared emission part and the second infrared emission part move alternately at a rated step length.

[0080] In this embodiment, the first infrared emission part and the second infrared emission part are not used to obtain the ice layer thickness, but only used to provide infrared radiation for continuous irradiation, and the thickness of the frozen covering layer can be measured based on the infrared convergent beam reflection method and the infrared thermal imaging method. And in this embodiment, the thickness of the frozen covering layer is obtained only once, and the acquisition position needs to be close to the blade tip. After determining the spot area based on the obtained thickness of the frozen covering layer, during the subsequent alternating movement of the first infrared emission part and the second infrared emission part, it always irradiates with a constant spot area. For example: define the spot area as 0.6 m 2 .

[0081] Under environmental conditions, there are two situations. One is that the frozen covering layer on the surface of the wind turbine blade is a glaze covering layer; the other is that the frozen covering layer on the surface of the wind turbine blade is a rime covering layer, or a mixed glaze covering layer.

[0082] a. When the ice-covered layer on the surface of the wind turbine blade is a glaze ice-covered layer, since the glaze ice-covered layer itself is transparent, infrared light can penetrate the transparent ice layer. By controlling the continuous irradiation time within the fixed-point light spot area to be less than 5 minutes, an interfacial water film is formed in the corresponding area.

[0083] Due to the long blades of the wind turbine generator, the light spot needs to move along the wind turbine blade. Under the environmental conditions where a glaze ice-covered layer can be formed, because the rotational speed at the blade root is low and the convection is relatively small, the ice layer at the blade root is relatively less. However, at a position about fifty or sixty meters away from the blade root, near the blade tip, there is a large amount of convection and the water cannot be shaken off, so there is more ice layer near the blade tip. Furthermore, in order to remove the glaze ice-covered layer on the blade, when the formed light spot moves along the length direction of the blade, at a constant power density, the irradiation time from the blade root to the blade tip can also be increased.

[0084] At the same time, there will be bubbles, impurities, etc. in the transparent ice layer. The influence of bubbles and impurities on light is mainly reflected in their scattering, refraction, and reflection of light. These effects can change the propagation direction and intensity of light. Therefore, in the actual scenario, the power density is controlled at 5 kW / m 2 ~7 kW / m 2 .

[0085] b. When the ice-covered layer on the blade surface is a rime ice-covered layer or a mixed ice-covered layer, since the rime ice-covered layer is a milky white ice crystal deposit and the infrared light penetration ability is relatively weak. However, because the formation of rime ice is a process in which water vapor molecules gradually accumulate and crystallize on the surface of an object, its structure is relatively loose and the connection between ice crystals is not tight enough. Compared with glaze ice, the adhesion of rime ice to the surface of the wind turbine blade is weaker. Therefore, by controlling the power density between 5 kW / m 2 ~7 kW / m 2 , the shedding of the rime ice-covered layer or the mixed ice-covered layer can also be achieved.

[0086] This application also discloses an ice-covered layer removal system for implementing a method for quickly removing the ice-covered layer based on the infrared mechanism.

[0087] Through the combination of the system and the method, the first infrared emission part expands a single beam of infrared light to form a large-area light spot area. By controlling the power density range, large-area and rapid de-icing of the wind power blade is achieved. And because the de-icing method belongs to "incomplete melting", the energy consumption required for de-icing is greatly reduced. Combined with the second infrared emission part, especially for the case where the ice-covered layer is relatively thick, since both the first light spot area and the second light spot area have the distribution of beam energy, the overlapping part can achieve energy superposition, which can accelerate the fracture of the ice-covered layer and thus accelerate the shedding of the ice layer, making the de-icing more efficient.

[0088] The above embodiments are only used to illustrate the technical concept and features of the present invention. The purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it should not be used to limit the protection scope of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to encompass all changes that fall within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A method for rapidly removing frozen cover based on infrared mechanism, characterized in that: Here’s how: S1. configuring at least one infrared emitting device at a fixed point, wherein the infrared emitting device is used to irradiate the leading edge of a downwardly inclined wind blade; S2. Based on the thickness of the frozen cover layer, determine the irradiation parameters of the infrared emitting device, wherein the irradiation parameters include the spot area, power density and irradiation time; at least one of the infrared emitting devices is used to emit an expanded light beam, and the irradiated spot area corresponding to each unit centimeter thickness of the frozen cover layer is not less than 0.55m 2 ; S3. Irradiate infrared light with rated power density to the leading edge of the wind blade, eventually forming an interface water film between the frozen cover layer and the surface of the wind blade. When the gravity of the frozen cover layer is greater than the sum of friction and stress, the frozen cover layer falls off the blade.

2. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 1, characterized in that: The infrared emitting device is configured with at least two groups, including a first infrared emitting unit and a second infrared emitting unit; the first infrared emitting unit forms a first light spot area, and the second infrared emitting unit forms a second light spot area; the first light spot area overlaps with the second light spot area.

3. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 2, characterized in that: The first infrared emitting part is used for emitting an expanded light beam, and the second infrared emitting part is used for emitting a concentrated light beam.

4. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 3, characterized in that: In step S2, the second infrared emitting unit is used to emit a focused light beam and project it onto the leading edge of the wind blade to obtain the thickness of the frozen cover layer at the corresponding position; based on the thickness of the frozen cover layer, the light spot area of ​​the first infrared emitting unit is determined, and an expanded light beam is emitted and projected onto the leading edge of the wind blade so that the first light spot area covers the second light spot area.

5. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 4, characterized in that: The first infrared emitting part moves along the length direction of the wind blade from the root to the tip at a rated step length; When the first infrared emitting part continues to irradiate, the focused light beam emitted by the second infrared emitting part reciprocates in the first light spot area along a direction perpendicular to the length of the wind blade.

6. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 5, characterized in that: In the wind blade ice-breaking area corresponding to any of the first light spot areas, the irradiation time of the second infrared emitting unit is not greater than the irradiation time of the first infrared emitting unit, so that the second infrared emitting unit withdraws from the corresponding blade ice-breaking area earlier than the first infrared emitting unit, and moves one step ahead along the length direction of the wind blade from the root to the tip.

7. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 5, characterized in that: The second light spot area is located at an end of the first light spot area away from the root of the wind blade.

8. The method for rapidly removing frozen covering layer based on infrared mechanism according to claim 2, characterized in that: The first infrared emitting part and the second infrared emitting part are both used for emitting an expanded light beam.

9. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 8, characterized in that: The first infrared emitting part and the second infrared emitting part both move alternately at a rated step length from the root to the tip along the length direction of the wind blade.

10. A method for rapidly removing frozen covering layers based on infrared mechanism according to claim 3 or 8, characterized in that: The power density of the infrared emitting device for emitting the expanded light beam is 1 kW / m 2 ~10kW / m 2 .

11. The method for rapidly removing frozen covering layer based on infrared mechanism according to claim 3, characterized in that: The wavelength of the light beam of the infrared emitting device used for emitting the expanded light beam is 750nm-860nm; the wavelength of the light beam of the infrared emitting device used for emitting the concentrated light beam is 1065nm-1940nm.

12. The method for rapidly removing frozen covering layer based on infrared mechanism according to claim 1, characterized in that: The incident angle of the light beam emitted by the infrared emitting device is 75° to 105°.

13. A frozen cover removal system, characterized in that: A method for rapidly removing frozen covering layers based on an infrared mechanism as described in any one of claims 1-9 or 11-12.

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