Focal ray paraboloid detection apparatus

Abstract

The utility model belongs to the solar energy reflector precision detection field. The utility model discloses a focal point ray parabola detection device, the ray of ray source or its extension line passes through the parabola focal point of supposing detecting, sets up the dial corresponding with the ray on the scale, the origin of dial and the intersection ray source are in the same parabola, the ray source and the scale through the support connection fixed in the same parabola, and the support and the ray source constitute "focal point ray parabola detection unit", the focal point ray parabola detection unit between each other parallelly arranged, and perpendicular to the keel, every focal point ray parabola detection unit divides into two groups of left and right symmetry, and the inside left and right interval is greater than or equal to the outer diameter of the heat collecting tube of the heat collecting device of the parabola of being detected. The utility model can form the detection result and the adjustment target on the spot after the application field, regular operation and detection.

Description

Technical Field

[0001] This utility model relates to a device for testing the installation accuracy of a trough-type parabolic solar reflector, belonging to the field of solar reflector accuracy testing technology. Background Technology

[0002] Concentrated solar power (CSP) plants convert sunlight into heat through a concentrating solar collector system. The heat is then transferred through a heat transfer system, with some of it used for power generation on the power generation island and the rest stored in a thermal storage island. This stored heat can be used to generate electricity when solar radiation intensity decreases or there is no sunlight. Due to its advantage of large-scale energy storage, CSP has gradually become the only form of energy storage power generation with large-scale commercialization after pumped storage power plants. Especially with the trend of energy structure development where the proportion of wind power and photovoltaic power plants is gradually increasing due to their volatility and intermittency, CSP is gradually becoming the only high-quality renewable energy source that can replace thermal power.

[0003] Solar thermal power plants are mainly divided into parabolic trough concentrators and tower concentrators. Tower solar thermal power plants have been unable to reach their optical efficiency design values ​​after more than ten years of commercial operation due to the large proportion of cosine loss in different areas in the morning and afternoon and their excessive dependence on air quality. As a result, countries have further accelerated the development of parabolic trough solar thermal power plants, which previously accounted for more than 80% of the global total.

[0004] Parabolic solar thermal power plants rely entirely on parabolic collectors for concentrated solar power. The conversion efficiency of solar thermal power depends entirely on the collectors, which account for approximately 40%-60%. The largest proportion of the losses is heat dissipation from the collector tubes, accounting for approximately 20%-40%. Other losses include the proportion of light reflected from the reflectors to the collector tubes, i.e., interception rate losses.

[0005] The optical interception rate depends on the accuracy of the parabolic surface of the collector and the diameter of the collector tube. In other words, the higher the accuracy of the parabolic surface, the higher the interception rate, and the larger the diameter of the collector tube, the higher the interception rate. However, as the diameter of the collector tube increases, the heat loss increases proportionally to the square of the diameter. Therefore, to ensure the optical interception rate, the diameter of the collector tube must be increased appropriately, but not too much. If the optical interception rate can be improved, the diameter of the collector tube can be reduced, thereby reducing the radiative heat loss.

[0006] Current testing technology for parabolic trough solar collectors involves using an optical imaging system of an optical testing device to photograph the parabolic surface of the collector, calculating the positional accuracy of its mounting base, and then calculating adjustment parameters for calibration. The problem is that the collector and collector tubes have a certain degree of gravitational sag, which the imaging system cannot identify individually. Therefore, both testing and adjustment are based on theoretical parabolic surface calculations. However, the systematic error caused by gravitational sag creates a systematic deviation between the "centerline of the collector tube as the actual operating focal line" and the "theoretical focal line corresponding to the theoretical reflector parabolic surface calibrated by the optical testing device." This systematic error leads to a decrease in the final collector tube interception rate, especially during periods of high solar radiation intensity (when the opening faces upwards), where the interception rate loss reaches 5%-10%, and the overall interception rate loss reaches 4%-8%. For a solar thermal power plant with an annual revenue of 500 million yuan, this translates to a loss of 20 million to 40 million yuan.

[0007] This systematic error also causes a decrease in the light concentration efficiency of the reflector focusing the light to the center line of the collector tube. Once the reflector deforms due to wind, a considerable portion of the light escapes outside the collector tube, and the interception rate drops rapidly. Therefore, even if the static interception rate of the collector tube reaches 90%-95%, the dynamic interception rate will still drop significantly due to the low light concentration efficiency, especially when there is wind or other mechanical interference from the collector.

[0008] Current optical inspection equipment cannot identify the deformation of the solar collector tube centerline versus the actual parabolic focal line caused by the gravity-induced sag of the solar collector tube. Instead, it can only detect and adjust the reflector according to the theoretical parabolic surface. This results in a large systematic error between the parabolic focal line and the actual operating solar collector tube centerline, leading to the aforementioned series of adverse effects. Consequently, the light concentration rate is low, resulting in poor dynamic anti-interference capability of the interception rate. Ultimately, the interception rate loss under all operating conditions can reach 4%-8%, or even higher.

[0009] Furthermore, current parabolic trough solar thermal power plants lack on-site testing equipment after the collector tubes are installed, which leads to a series of problems. Firstly, the collectors are mounted on column bearings at both ends of each unit, which is several meters long. Adjacent collectors are then rigidly connected before the collector tubes are installed and the heat transfer medium is filled. This causes deformation and sagging in both the collectors and the collector tubes, affecting the optical interception rate. Secondly, during operation, due to wear and tear, reflectors and collector tubes need to be replaced periodically. However, without on-site parabolic surface testing equipment, the parabolic accuracy of the collectors cannot be calibrated after reinstallation. Utility Model Content

[0010] This invention relates to a focal-focus parabolic reflector testing device, which can be used for on-site assembly accuracy testing of parabolic reflectors in parabolic trough solar thermal power plants. The testing device can simulate the gravitational deformation of the collector tubes, and features a convenient keel mounting base and nut clamps, enabling precise and rapid focusing and positioning, thus eliminating systematic errors in the testing process.

[0011] Furthermore, by utilizing the principle of parallel light reflected from a ray source simulating the focal point of a parabolic surface to a reflecting mirror, the position and angular accuracy of the parabolic surface of the reflecting mirror can be detected.

[0012] Furthermore, helium balloons are used to support the testing equipment, thereby reducing the impact of the testing equipment on the gravity of the solar collector. This also facilitates hoisting, moving, and centering installation, making it simple, quick, and accurate.

[0013] A focal-area parabolic surface detection device includes a radiation source, a scale, and a support frame. The radiation source's rays or their extensions pass through the focal point of the parabolic surface to be detected. The scale is equipped with a dial corresponding to the radiation source, and the origin of the dial is on the same parabolic surface as the radiation source. The radiation source and the scale, which are on the same parabolic surface, are connected and fixed by a bracket. The bracket and the radiation source constitute a "focal-area parabolic surface detection unit." The focal-area parabolic surface detection units are arranged parallel to each other and perpendicular to the support frame.

[0014] In this unit, the X-ray source support of each focal X-ray parabolic surface detection unit is divided into two symmetrical groups, and the distance between the inner left and right sides of the two groups of X-ray source supports is greater than or equal to the outer diameter of the heat collection tube of the parabolic surface heat collector being tested.

[0015] Preferably, keel mounting seats are provided at both ends of the keel along its length, and the length L between the two ends of the keel mounting seats along its length is the same as the spacing between the mounting brackets of the heat collection tubes of the parabolic reflector heat collector being tested. Two mounting seats are provided on the left and right sides of each end of the length direction.

[0016] Preferably, the stiffness between the keel mounting bases at both ends of the parabolic surface testing equipment along its length is the same as the stiffness of the heat collection tubes of the parabolic trough solar collector being tested.

[0017] Preferably, the number and spacing of the focal ray parabolic detection units on the keel are the same as the number and spacing of the cross-section of the reflector mounting base of the parabolic trough reflector collector to be detected, and they are located on the same parabolic cross-section.

[0018] Preferably, the number of dials on the scale is the same as the number of X-ray sources, and the origin of the dial is located on the path of the parallel line reflected by the parabolic reflector from the focal point of the cross-sectional profile of the parabolic surface to be detected.

[0019] Preferably, the scale dial is transparent, and a reflector with an angle of 45°-90° to the scale dial is provided on the upper side of each scale dial, facing the side of the keel axis.

[0020] Preferably, a camera imaging system is installed on the upper side of the keel end facing the reflector.

[0021] Preferably, the material of the dial is the same as the radiation source material, which can convert the coordinate position of the radiation hitting the dial into an electrical signal and transmit it to the data processing system to calculate the deviation.

[0022] Preferably, the camera imaging system can capture images of the scale dial and the light spot emitted by the X-ray source, and identify the target coordinate position of the light spot on the scale dial through the image recognition data processing system, then calculate the deviation of the mounting bracket, and obtain the recommended adjustment height value of the mounting bracket.

[0023] Preferably, the collector tube fixing bolt is equipped with a nut clamp, the nut clamp is provided with a positioning groove and a first V-shaped opening, and the width of the positioning groove is the same as the thickness of the keel mounting base.

[0024] Preferably, the keel mounting base adopts a V-shaped opening, the upper shape of which is the same as the positioning groove of the nut clamp, and the width of the V-shaped opening is greater than the width of the positioning groove of the nut clamp.

[0025] Preferably, the upper part of the testing equipment is equipped with a hoisting structure, which is a sling or a lug.

[0026] Preferably, a helium balloon is installed on the hoisting structure, and the buoyancy of the helium balloon is similar to or slightly greater than the weight of the detection equipment.

[0027] Preferred option: A positioning thin nut is provided between the nut clamp and the collector tube fixing bolt.

[0028] Preferred configuration: The helium balloon is equipped with a traction cable, with a counterweight mass block suspended on each side.

[0029] Preferably, a level is installed on the detection equipment, and the signal is connected to the data processing system.

[0030] The method of using the focal ray parabolic surface inspection equipment is based on the equipment itself and includes the following steps:

[0031] Adjust the daily angle of the solar collector to a horizontal direction with the parabolic opening facing 0° or 180°, so that the mounting bracket of the solar collector tube is in a low and easy-to-operate position.

[0032] Assemble the nut clamps one by one onto the outer studs of the collector tube mounting bolts without changing the state of the collector tubes fixed on the inner side of the mounting bolts. After installation, use measuring tools to calibrate the position of the two nut clamps in the x-axis direction of each pair of nut clamps at the same collector tube installation section, so that they are in a symmetrical position on the center line of the collector tube, and the distance between the inner shafts of the positioning grooves of the left and right nut clamps reaches the specified length, that is, the same as the left and right distance of the keel mounting base.

[0033] After all the nuts and clamps to be tested are installed in place, the angle of the solar collector is adjusted daily to a 90° angle with the opening facing upwards.

[0034] The helium balloon lifts the testing equipment and raises it to the top of the solar collector tube to be tested, bringing the keel mounting base of the testing equipment close to the four nut clamps on the four mounting bolts of the solar collector tube to be tested;

[0035] The counterweight is gradually lowered, causing the keel mounting base of the testing equipment, which is directly above the solar collector being tested, to align with the nut clamp as it falls. This allows the keel mounting base to be inserted into the positioning groove through the first V-shaped opening of the nut clamp, achieving precise positioning.

[0036] The measurement data transmitted from the level of the testing equipment to the data processing system is used to check whether the level of the ruler meets the requirements. If it does not meet the requirements, the cause is investigated. If it meets the requirements, the reflector testing work begins.

[0037] Based on the deviation between the coordinate position of the ray spot reflected by the reflector to the scale dial and the origin of the scale dial, the data processing system checks whether the ray spot coordinate value is within the allowable deviation range, and calculates the recommended adjustment size of the reflector mounting base corresponding to the ray spot that exceeds the tolerance.

[0038] Lift the counterweight block, use a helium balloon to lift the testing equipment, move it to the corresponding solar collector reflector unit of the adjacent solar collector tube to be tested, and repeat the above testing and adjustment process to complete the adjustment of the entire solar collector circuit.

[0039] This utility model has the following beneficial effects:

[0040] 1. The parabolic detection equipment used in this case employs the same span and stiffness as the solar collector, simulating the sag deformation of the solar collector. This causes the focal points of the ray sources in each focal ray parabolic detection unit on the keel to sag accordingly, matching the actual sag of the solar collector tubes along the keel during use. This achieves precise focusing. Then, using this focal point as a reference, the position and angle of the parabolic reflector are adjusted to match the actual operating state. This eliminates the systematic errors caused by the traditional parabolic detection equipment that detects based on the theoretical parabolic focal line, thereby improving the optical interception rate of the solar collector.

[0041] 2. The focal ray parabolic surface inspection equipment uses the actual centerline of the solar collector tube as the focal line to inspect the reflector surface. This is equivalent to tolerating the cumulative deviation of the dimensional chain in a series of installation and manufacturing processes that have misaligned the installation reference of the solar collector tube mounting bracket. Then, using this as the parabolic focal line reference to adjust the reflector, the inspection and adjustment only target the accuracy of the reflector surface relative to the actual focal line, and are not affected by the deviation of the solar collector support structure. The final accuracy is mainly affected by the accuracy of the inspection equipment itself and the manufacturing accuracy of the reflector surface profile, which can significantly improve the parabolic accuracy of the parabolic mirror surface relative to the actual focal line.

[0042] 3. Reduced manufacturing and assembly precision requirements for solar collectors: Since the focal ray parabolic surface inspection equipment achieves precise focusing, the manufacturing and assembly precision of individual collector components is almost irrelevant, as long as the reflector's installation position and angle are adjusted. All components can be "matched" in the final stage, achieving a "fault-tolerant" effect. There is no need to impose excessively high requirements on the assembly precision of collector components and processes, thereby reducing costs and saving labor time.

[0043] 4. The focal X-ray parabolic surface inspection equipment can perform real-time inspections during the assembly process, reducing the need for separate hoisting and inspection steps, saving assembly time and space, improving assembly efficiency, and reducing assembly time.

[0044] 5. The focal ray parabolic detection equipment not only significantly improves the light interception rate, but also significantly improves the light concentration rate, making the reflected light more concentrated near the focal line and away from the edge of the heat collection tube.

[0045] 6. Significantly improves the interception rate of the solar collector under all operating conditions and external interference such as wind speed. Through precise focusing detection by the focal ray parabolic detection equipment, the concentration rate is greatly improved, making the reflected light more concentrated near the focal line and away from the edge of the collector tube. In actual use, under different daily angles, the amount of sag of the solar collector changes, and when wind speed interference causes the collector tube and reflector to deviate from the optimal position, the reflected light from the parabolic reflector is still less likely to deviate beyond the edge of the collector tube, improving its robustness against interference. This is conducive to improving the vectorized interception rate under all operating conditions, thereby improving the overall solar thermal power plant concentration rate.

[0046] 7. Due to the precise focusing detection of the focal ray parabolic detection equipment, the light concentration rate is greatly improved, causing the reflected light to be further away from the edge of the heat collector tube. This lays the foundation for a significant reduction in the diameter of the heat collector tube. Even with a reduction in the diameter of the heat collector tube, the interception rate is almost unaffected, and the vectorized interception rate under all operating conditions in windless conditions is not affected. Attached Figure Description

[0047] Figure 1 This is a three-dimensional schematic diagram of the present invention;

[0048] Figure 2This is a structural diagram of the parabolic trough solar collector being tested;

[0049] Figure 3 This is a schematic diagram of the installation structure of the heat collection tube on the mounting bracket;

[0050] Figure 4 This is a schematic diagram of the state of the heat collection tube when it is drooping under gravity;

[0051] Figure 5-1 This is a schematic diagram of the installation of the camera imaging system with the keel and scale in Example 4;

[0052] Figure 5-2 yes Figure 5-1 Top view;

[0053] Figure 6 This utility model relates to a three-dimensional focal X-ray parabolic detection device. Figure 2 ;

[0054] Figure 7-1 This is a partial schematic diagram of the installation of the keel mounting base and mounting bracket in Embodiment 2;

[0055] Figure 7-2 This is a side view of the installation of the present invention and the tested parabolic trough solar collector in Embodiment 2;

[0056] Figure 8-1 This is a partial schematic diagram of the nut clamp in Example 6;

[0057] Figure 8-2 This is a schematic diagram of the installation of the nut clamp on the collector tube mounting bolt in Example 6;

[0058] Figure 9-1 This is a side view of the keel mounting base in Embodiment 2;

[0059] Figure 9-2 This is a partial schematic diagram of the keel mounting base;

[0060] Figure 10 This is a schematic diagram illustrating the interaction between the helium balloon and the focal ray parabolic detection device in Example 8;

[0061] Figure 11-1 This is a state diagram of the solar collector when the daily angle is 90°.

[0062] Figure 11-2 It is a state diagram of the solar collector when the daily angle is 0° or 180°;

[0063] Figure 12 It is a graph showing the changes in the positional accuracy of the heat collector tube and the positional accuracy of the reflector as a function of the daily angle.

[0064] Figure 13This refers to the situation where light reflected by a parabolic mirror is intercepted by the heat collection tube. Figure 1 ;

[0065] Figure 14 This refers to the situation where light reflected by a parabolic mirror is intercepted by the heat collection tube. Figure 2 ;

[0066] Figure 15 This is a distribution map of concentrated light energy intensity;

[0067] Figure 16 This is a schematic diagram of the light concentration ratio;

[0068] Figure 17 This is a graph showing the heat loss of the collector tubes in a parabolic trough solar thermal power plant as a function of temperature. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the present utility model. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the present utility model.

[0070] This utility model proposes a focal ray parabolic surface inspection device and its usage method, which is mainly used to inspect the mirror surface of the parabolic trough solar collector during the power generation process of a parabolic trough power plant (on-site). Since the collector tubes at the power generation site have already been installed, it would be very troublesome to disassemble the collector tubes for inspection. Therefore, the focal ray parabolic surface inspection device proposed in this utility model can perform mirror installation point inspection without disassembling the collector tubes, realizing real-time online inspection.

[0071] Example 1

[0072] This embodiment is a focal ray parabolic surface detection device, such as... Figure 1 As shown, it includes a radiation source 1, a scale 2, and a keel 3.

[0073] The rays from each ray source 1, or their extensions, intersect at a point, pass through the focus of the parabolic surface to be detected, and lie in the same plane; this point is called the "ray source focus".

[0074] The scale 2 is equipped with a dial 21 that corresponds one-to-one with the X-ray source 1 and is located on the same parabolic plane as the X-ray source 1. The X-ray source 1 and the scale 2 are fixedly connected by the bracket 11 to form an integral structure. The bracket 11 and the X-ray source 1 constitute the "focal X-ray parabolic surface detection unit 10".

[0075] In the focal X-ray parabolic surface detection unit 10, the number of "X-ray sources 1" is consistent with the number of "reflector mounting supports 02 within the cross-section of the parabolic trough collector being tested". The number of "scales 21" on each scale 2 is consistent with the number of "reflector mounting supports 02 within the cross-section of the parabolic trough collector being tested", and they correspond one-to-one, so that the number of X-ray sources 1 and scales 21 is consistent with the number of reflector mounting supports 02 within the cross-section of the parabolic trough collector being tested, which facilitates the completion of the test in one go.

[0076] For details regarding the structure of the parabolic trough solar collector under inspection, please refer to [link / reference]. Figure 2 One of the most critical steps in assembling the solar collector is to mount each of the parabolic reflectors 7 onto the reflector mounting brackets 02 on the support frame of the solar collector. Each reflector has four mounting surfaces on its back that correspond to the reflector mounting brackets 02.

[0077] The height of each reflector mounting bracket 02 determines the accuracy of the parabolic position and angle of the reflector 7, especially affecting the relative position of the reflector and the focal line of the parabolic surface.

[0078] The solar collector is equipped with several sets of mounting brackets 04, each with mounting holes 05. The solar collector tubes 03 are mounted on the mounting brackets 04 through the mounting holes 05. The parabolic focal length of the solar collector... It is the line connecting the midpoints of the center lines of the mounting holes 05 on each set of mounting brackets 04.

[0079] like Figure 3 As shown, the collector tube 03 is assembled into the mounting hole 05 of the mounting bracket 04 via the mounting shaft 09, therefore the focal wire... It is also the centerline of collector tube 03.

[0080] Therefore, it is essential to ensure that each reflecting mirror is aligned with the center line. The spatial positions between them meet the requirements. The height of the reflector mounting bracket 02 needs to be adjusted so that the focal point in the parabolic cross section corresponding to each reflector mounting bracket 02 and the eight reflector mounting brackets 02 satisfy the parabolic equation relationship. In this way, the light rays emitted from the ray source 1 and reflected by the reflectors on the reflector mounting bracket 02 should be vertically upward and mutually parallel. Thus, a scale 21 is set on the scale 2 along its path, and the origin of the scale 21 corresponding to each ray source 1 is placed on the path of the reflected parallel light.

[0081] When the height of the reflector mounting bracket 02 deviates, the position and angle of the corresponding reflector 7 will also deviate, causing the position of the reflected light hitting the target on the dial 21 to deviate from the origin. Therefore, based on the coordinate position of the light spot hitting the target on the dial 21, the deviation of the reflector mounting bracket 02 can be calculated using the parabolic equation, and the adjustment target value can be calculated. By adjusting the height of the reflector mounting bracket 02 according to the adjustment value, the reflector can be adjusted to the target position and angle, thereby causing the light spot to hit the target to the origin, thus meeting the deviation requirements.

[0082] In order to complete the inspection of all the reflector mounting supports 02 of each collector at one time, several sets of parallel inspection units are connected into a fixed whole by the keel 3 perpendicular to the parabolic surface inspection unit 10 of the focal ray. The number and position of the scale 2 are the same as the number and position of the cross-section of the reflector mounting support 02 and are on the same plane. The number of scales 21 of the scale 2 is the same as the number of reflector mounting supports 02 and corresponds one-to-one in the vertical direction.

[0083] In addition, the X-ray source support 11 of each focal X-ray parabolic detection unit 10 is divided into two symmetrical groups, and the distance between the inner left and right sides of the two groups of X-ray source support 11 is greater than or equal to the outer diameter of the heat collection tube of the parabolic heat collector being tested.

[0084] Further as Figure 6 As shown, the X-ray source bracket 11 of each detection unit is divided into two symmetrical groups. The inner spacing of the X-ray source bracket 11 is greater than or equal to the outer diameter of the heat collection tube of the parabolic heat collector being tested. In this way, when the detection equipment is installed, the X-ray source bracket 11 and its fixed X-ray source 1 can fall across the heat collection tube 03, so that the X-ray focus of the X-ray source 1 is focused with the center line of the heat collection tube 03 (which is also the actual parabolic focus of the heat collector).

[0085] Example 2

[0086] This implementation example Figure 6 , Figure 7-1 and Figure 7-2 As shown, keel mounting bases 31 are provided at both ends of the keel 3 along its length. The length L between the two ends of the keel mounting bases 31 along the length of the keel 3 is the same as the spacing and rigidity of the mounting bracket 04 of the heat collection tube of the parabolic reflector heat collector being tested. This makes the downward gravity of the keel and each detection unit under the action of gravity the same as the downward gravity of the heat collection tube, so that the focal point of the X-ray source 1 is better focused with the center line of the heat collection tube.

[0087] Furthermore, a keel mounting base 31 is provided on each of the left and right sides (x-axis direction) at both ends of the keel 3 (e.g., Figure 9-1 As shown), the distance between the left and right keel mounting bases 31 is the same as the spacing of the outer stud portion of the left and right heat collector tube mounting bolts 07.

[0088] By setting the four keel mounting seats 31 at the four corners of the keel 3, the heat collection tube mounting bolts 07 of the four mounting brackets 04 of the heat collection tube 03 protrude from the outside of the mounting bracket 04. These four points are rigidly positioned with the installation reference of the heat collection tube, reducing the installation error of the testing equipment.

[0089] Furthermore, the X-ray focus of the X-ray source 1 of the detection unit on the detection equipment is positioned relative to the xy plane of the keel 3 so that it is also positioned relative to the xy plane of the center line of the heat collection tube relative to the four heat collection tube mounting bolts 07 (the X-ray focus of the X-ray source 1 is on the center line of the positioning bolts 07).

[0090] The relative position of the focal ray parabolic detection unit 10 on the keel 3 along the z-axis also corresponds one-to-one with each parabolic cross section of the reflector mounting bracket 02 of the solar collector and is on the same plane.

[0091] The purpose of making the length and rigidity of the detection equipment the same as that of the heat collector tube is to ensure that the sag of the detection equipment is the same as that of the heat collector tube, so that the focal point of the X-ray source 1 is aligned with the centerline of the heat collector tube. The significance of this in eliminating systematic errors is as follows:

[0092] Because the collector tubes are 4-5 meters long and 70-100 millimeters in diameter, with both ends installed on the collector tube mounting brackets and the middle section suspended, some sections experience downward displacement of tens of millimeters. If not corrected, this systemic error causes the collector reflector to still adjust its position and angle according to the theoretical parabolic surface, often resulting in a 2-4% loss in the optical interception rate of the collector tubes.

[0093] The specific effects of solar collector sagging due to gravity are as follows: Figure 4 As shown, the solid line represents the outer contour of the collector tube when it is not drooping, and the dashed line represents the outer contour of the collector tube when it is drooping. Taking a 100mm diameter collector tube as an example, when the middle of the collector droops by 50mm, the vertical contour shown in the figure will deviate from the collector tube contour by 25%. From the perspective of the reflector, the design deviation of the dashed contour from the theoretical and practical contour also reaches 5%-8%. As the collector tube rotates, the focusing angle of the opening facing upwards near noon is different. The collector often has the largest length-to-diameter ratio and the largest drooping deviation in the middle. As the other openings tilt towards the horizontal direction, the length-to-diameter ratio of the collector decreases, the drooping deviation in the middle decreases, and the above deviations decrease. Thus, the cumulative deviation of the openings at 0° and 180° also reaches 3%-6%.

[0094] This type of collector sag, causing a deviation in the parabolic surface and resulting in a synchronous sag of the collector tubes, is impossible to identify and measure with traditional parabolic surface testing equipment. Often, the parabolic surface of the collector is tested according to a standard theoretical parabolic surface and calibrated to a parabolic surface based on the theoretical focal line. However, in actual operation, the collector tubes sag along with the middle of the collector, causing the light reflected by the reflector to... Figure 4 The deviation zone between the solid line and the dashed line of the collector tube sometimes deviates from the collector tube, resulting in the loss of some concentrated light energy and causing a 3-6% loss in concentrated light.

[0095] This deviation is caused by the traditional parabolic surface testing equipment adjusting the reflector according to the installation deviation of the over-reflecting surface based on the theoretical focal line. It always exists in the category of "systematic deviation". Therefore, in order to eliminate this systematic error, the diameter of the heat collection tube is often increased. However, for every 8% increase in the diameter of the heat collection tube, the surface area of ​​the heat collection tube increases by more than 9%, which further leads to an increase of more than 9% in the radiative heat loss of the heat collection tube.

[0096] For parabolic trough solar collectors, the light-gathering efficiency is about 40-60%. A portion of the loss is due to the light concentration rate loss, which is the light that cannot be intercepted by the solar collector tubes due to the parabolic reflector. This is also known as the "interception rate loss". The larger part of the loss is the heat dissipation loss of the high-temperature solar collector tubes. Therefore, the deviation of the solar collector from the theoretical focal line will cause a series of continuous losses.

[0097] If the drooping state of the solar collector can be eliminated, and the parabolic detection equipment can identify and quantify the actual drooping focal line of the parabolic surface, and adjust the parabolic reflection system to match the drooping focal line accordingly, then on the one hand, the optical interception rate of the solar collector can be improved, and on the other hand, the diameter of the solar collector tube can be reduced, while still allowing it to absorb the concentrated light of the parabolic reflector with a high interception rate. This would significantly alleviate the contradiction between the increased thermoelectric conversion efficiency of the solar collector tube and the geometrically increasing radiative heat loss after the solar collector tube heats up.

[0098] Therefore, the parabolic detection equipment used in this case employs the same span and stiffness as the solar collector to simulate the sag deformation of the solar collector. This causes the ray focus of the ray source 1 in the parabolic detection unit 10 on the keel 3 to sag accordingly, which is the same as the sag state of the solar collector tube along the keel 3 during actual use. This achieves precise focusing. Then, using this focus as a reference, the position and angle of the parabolic reflector are adjusted to match the actual operating state. This eliminates the systematic error caused by the detection of the theoretical parabolic focal line by the traditional parabolic detection equipment and improves the optical interception rate of the solar collector.

[0099] Taking a solar thermal power plant using parabolic trough collectors as an example, if the annual power generation revenue is 500 million yuan, then by eliminating system errors through the aforementioned method of eliminating optical speculation and increasing the annual comprehensive interception rate by 2%, the annual power generation revenue can be increased by 10 million yuan, demonstrating the significant benefits.

[0100] This further reduces the solar concentration efficiency of the collector tubes, causing the annual overall loss of the collector to exceed 2-4%.

[0101] Therefore, the stiffness of the detection equipment is made the same as that of the heat collection tube to achieve more accurate focusing of the X-ray source 1 and the center line of the heat collection tube, thus eliminating the loss caused by system error.

[0102] The parabolic reflector accuracy of the parabolic concentrator in current parabolic trough solar thermal power plants is not based on the actual centerline of the collector tubes, i.e., the focal line, as the positioning basis for the parabolic surface. Therefore, there are many links in the dimensional chain between the collector tube installation reference, the reflector installation reference, and the measurement reference of the parabolic surface testing equipment. In particular, the cumulative error band of the dimensional chain between the collector tube installation reference and the parabolic surface testing equipment is not closed-loop, ultimately affecting optical efficiency indicators such as the collector's concentration interception rate and the concentrated solar power generation efficiency of the solar thermal power plant. To better understand this, it is necessary to analyze it from the definitions of two optical efficiency indicators: "full-condition vectorized interception rate" and "concentration concentration rate," as detailed below:

[0103] 1. Vectorized light-gathering interception rate under all operating conditions

[0104] The interception rate of traditional parabolic trough solar thermal power plant collectors is a static interception rate per collector unit under a certain daily angle, which has limitations and cannot objectively reflect the "all-time and all-space" concentration efficiency of the collectors and the concentrated solar power generation efficiency.

[0105] The parabolic trough reflector of a parabolic trough solar thermal power plant utilizes the parabolic principle to project parallel sunlight onto the parabolic reflector and focus it onto the focal line connecting the focal points of each parabolic section, hereinafter referred to as the "focal line".

[0106] However, due to manufacturing and assembly errors in the solar collector, the focused light cannot be precisely reflected to the focal line or the solar collector tube located at the focal line. The traditional method for evaluating the concentrating efficiency is to project parallel sunlight onto a parabolic mirror and then measure the proportion of the reflected light that is intercepted by the solar collector tube located at the focal line; this is called the "interception rate". ,and The interception rate is measured and statistically analyzed using the collector unit. Generally, the acceptance standard for interception rate in parabolic trough solar thermal power plants is an average value of not less than 97%.

[0107] The acceptance test status for this interception rate is often that the solar collector is at 0%. 0 Or 180 0The interception rate when the opening faces east or west at the daily angle. However, this is not the actual daily angle at which the solar collector operates. The interception within the range cannot reflect the true concentrating efficiency of the solar collector.

[0108] Therefore, we will now introduce the concept of full-condition, vectorized focused light interception rate.

[0109] (1) Based on the daily angle of the solar collector Interception rate as the independent variable .

[0110] Traditional interception rate Acceptance testing involves checking the solar collector's angle daily. Concentration interception rate of solar collector unit at angles of 0° and 180° The solar collector has different daily angles. Corresponding interception rate ( There are significant differences;

[0111] Let the length of the solar collector unit be... Both ends are bearing support points, such as Figure 1 Width of the support frame in the direction of the collector opening Height of the support frame in the height direction of the solar collector And solar collectors generally That is, the width of the opening of the collector support frame is much greater than its height.

[0112] like Figure 11-1 As shown, =90 0 At that time, the aspect ratio in the direction of gravity, i.e., the y-direction, is... ,like Figure 11-2 As shown, in At 0° and 180°, the aspect ratio in the direction of gravity is... ,because ,therefore, Then for length The solar collector, which is over ten meters high and suspended in the middle, has a sag in the middle. They are also different. =90 0 It is the amount of drooping in the middle. Reaching a maximum size of tens of millimeters, and =0° and 180° represent the minimum sag of the middle part of the solar collector, approximately a few millimeters. A sag of tens of millimeters will cause the collector tube to sag as well. For a collector tube with a diameter of D=80mm, the impact will be significant, thus having a substantial effect on the interception rate.

[0113] A drooping collector will cause the positions of the collector tubes and reflectors to deviate from the theoretical focus and parabolic surface of the parabola, thus affecting the positional accuracy of the collector tubes. and the positional accuracy of the reflecting mirror This, in turn, affects the interception rate, and therefore the following functional relationship exists:

[0114] (1)

[0115] In the formula, , With each day's angle Changes such as Figure 12 As shown.

[0116] With each day's angle =90 0 At this time, the sag in the middle of the collector is the greatest, and the deviation of the corresponding collector tubes and reflectors in the middle from their standard positions is the largest. , It is also the largest, with the corresponding positional accuracy. , At worst, this will also affect the interception rate of the solar collector unit. Therefore, the interception rate should include the daily angle. A function of variables.

[0117] (2) By wind speed Interception rate with interference as the independent variable

[0118] Solar collectors at different wind speeds Under the influence of the wind, the degree of vibration of the reflector and the amount of deformation of the heat collection tube will vary, thus affecting the positional accuracy of the heat collection tube and the reflector. Therefore, the positional accuracy of the heat collection tube and the reflector is also affected by the ambient wind speed v during operation. , This further affects the interception rate. Therefore, the following relationship should exist:

[0119] (2)

[0120] (3) Vectorization of the interception rate of the solar collector unit

[0121] The sag of the collector unit varies along its length, resulting in different positional accuracies for the parabolic collector tubes and reflector. Therefore, the interception rate of the parabolic cross-section along the Z-axis of a given length direction is affected by the Z-coordinate.

[0122] (3)

[0123] Furthermore, at different widths (x-coordinates) of the parabolic cross section of the solar collector (Z-coordinate), a beam of light is incident on the focal line. The interception rate has only two possibilities: either 100% is intercepted and absorbed by the collector, or it is not intercepted and absorbed at all (0% interception rate). Therefore, the specific interception rate at a given vector coordinate (z, x) of the solar collector's reflection, in all-time... = Interception rate across the "full operating condition" range under interference conditions (0°→180°) and wind speed v. :

[0124] (4)

[0125] So, what is the interception rate of the parabolic cross section at the Z-coordinate of the solar collector?

[0126] (5)

[0127] Its physical meaning is that the solar collector is at a certain daily angle. Under wind speed V, the interception rate of the parabolic cross section element at the z-coordinate is given by the following formula. There are only two scenarios: 0%, 100% unblocked, and blocked. Further, from equation (4):

[0128] (6)

[0129] Its physical meaning is Under a certain operating condition, the interception rate of the solar collector reflector (z, x) is affected by the positional accuracy of the solar collector tube and the reflector. ,Influence.

[0130] Furthermore, the interception rate is calculated using the collector unit as the statistical unit. :

[0131]

[0132] = (7)

[0133] Its physical meaning is the daily angle of the solar collector unit. Interception rate under wind speed v condition.

[0134] when =0°, 180°, wind speed v=0m / s This refers to the interception rate during the acceptance testing of solar collectors in the traditional sense.

[0135] Furthermore, if the interception rate of the collector unit is within the full operating range of θ = 0° → 180°, then

[0136] (8)

[0137] = (9)

[0138] The physical meaning of equation (9) is the interception rate of the solar collector under all operating conditions in the daily range of θ=00~1800.

[0139] Among them, the static interception rate is when there is no wind (v=0), and the dynamic interception rate is when there is wind interference (v>0).

[0140] In summary, by redefining the full-condition vectorized interception rate of the focusing solar collector using "day" (θ=0°→180°) as the time unit, the solar collector as the unit, and the vectorized coordinates of each reflector of the (z, x) solar collector as the statistical unit, we can accurately calculate the focusing efficiency of the solar collector under the "all-time and all-space" state, and reconstruct the theoretical system of the optical efficiency of the solar collector. This lays the foundation for the subsequent reconstruction of the technology, process, and testing system of the solar collector based on this.

[0141] 2. Concentration efficiency of parabolic trough solar collectors

[0142] Next, we introduce the concept of solar collector concentration ratio. Based on the same interception rate of the solar collector, the concentration ratio more accurately reflects the solar collector's concentration efficiency, especially the solar collector's concentration efficiency under different daily angles and wind speeds and other disturbances.

[0143] For parabolic trough solar thermal power plants, the degree to which the parabolic reflectors of the trough concentrate parallel sunlight to the focal line of the parabola or the center line of the collector tubes is called the concentration ratio. .

[0144] like Figure 16 As shown, ray 1 is closer to the center of the collector tube or the focal line, and closer to... The farther the edge of the collector tube is, the higher the light concentration rate. However, light ray 2 is already close to the edge, and the distance from the center reaches the radius of the collector tube. Although the collector tube intercepts the light ray to meet the interception rate requirement, it is already at the edge. If there is any slight shaking or deviation, the interception rate will become 0, indicating that the light concentration rate is too low, the anti-interference ability is poor, or a smaller collector tube cannot be used.

[0145] like Figure 13 As shown, although the light reflected by the parabolic mirror is intercepted by the heat collection tube, achieving a 100% interception rate, the concentration near the center line is not high enough, resulting in a corresponding distribution of concentrated energy intensity as shown in the figure. Figure 15 As shown in curve 1.

[0146] like Figure 14 As shown, the light reflected by the parabolic mirror is also 100% intercepted, but the concentration is high near the center line, and the corresponding concentrated light energy intensity distribution is as follows. Figure 15 Curve 2.

[0147] in Figure 13 The solar collector shown has a high concentration ratio. It's too low, and Figure 2 The concentration ratio shown The concentration of light is relatively high. When the collector tube is disturbed by dynamic interference such as wind speed or the position of the reflector is deviated, the difference in the concentration of light in the collector will become apparent.

[0148] Concentration rate Higher-profile collectors have stronger anti-interference capabilities when the positions of the collector tubes and reflectors deviate from the standard positions.

[0149] Its specific quantitative definition is as follows:

[0150] Let the radius of the heat collection tube be... ;

[0151] When parallel sunlight is reflected by a mirror to the vicinity of the focal line of the parabolic surface, the vertical distance ΔR from the focal line is defined as the focusing deviation.

[0152] Furthermore, the concentration deviation rate is defined as follows:

[0153]

[0154] The relevant variables for concentration deviation rate include z, x, and , v, that is, the axial position of the collector z, the width of the parabolic cross section corresponding to the axial x position, the (z, x) coordinate position of the collector in the daily angle of the collector. Concentration deviation rate of parallel sunlight reflected to the focal line of the parabolic mirror under wind speed v:

[0155] (10)

[0156] Furthermore, we introduce the concept of light concentration rate, also known as light concentration ratio.

[0157] (11)

[0158] Equation (11) represents the coordinates of the (z, x) points of the solar collector reflector. Distance from the focal line of the parabolic mirror to the reflected parallel sunlight under daily angle and wind speed interference. With the radius of the heat collection tube The ratio of these is its deviation rate. And... The reflected light deviates from the radius. The distance between the collector tubes and the radius of the collector tubes Proportion, this value The larger the relative The higher the radius of the collector tube, the more concentrated it is towards the focal line. ,but Compared to Radius of the solar collector tube concentrating power When the maximum value is reached, the heat collection tube will deviate. The beam of light can still be reflected to the edge of the deviated heat collector tube, that is, for the (z, x) coordinate point of the reflector, the light is affected by... The interference resistance margin of the heat collection tube reaches [value missing]. .

[0159] and This is related to the positional accuracy of the heat collection tubes and reflectors, which deviate from their standard profiles and parabolic curves.

[0160] (12)

[0161] Furthermore, the concentrating power function for a solar collector located on a parabolic surface at section z is as follows:

[0162] (13)

[0163] in, It is the width of the parabolic surface of the solar collector reflector.

[0164] Furthermore, the concentration ratio of the solar collector unit :

[0165]

[0166] (14)

[0167] Furthermore, the solar collector unit uses "day" as the time unit, and the angle is measured day by day. =Concentration efficiency under all operating conditions within the range of 0° to 180°:

[0168]

[0169] = (15)

[0170] Furthermore, if v=0, it represents the static concentration efficiency of the solar collector under static conditions where the wind speed is zero.

[0171] In summary, As a vectorization of the specific (z, x) coordinates of the mirror and The definition of vectorized solar concentration ratio, considering wind speed interference across the entire operating range of 0° to 180°, objectively reflects the degree to which the solar collector reflector focuses parallel sunlight relative to the focal line under different relevant variables, and also indicates the degree to which the reflector is closer to the focal line than the edge of the collector tube. The higher the parameter, the stronger the solar collector's anti-interference ability.

[0172] Therefore, by defining the concentration ratio, it can be used as a measurement parameter for the manufacturing precision of solar collectors, as well as a parameter for improving the ability to concentrate solar heat collection and further increasing the power generation of solar thermal power plants by resisting interference.

[0173] 3. Significance of the solar collector optical efficiency system constructed from vectorized interception rate and concentration rate under all operating conditions

[0174] (1) Only the vectorized interception rate under all operating conditions can objectively and truly reflect the "all-time and all-space" concentrating and collecting efficiency of the concentrating solar collector.

[0175] The full-condition vectorized interception rate is based on the coordinates (z, x) of each collector unit and their values ​​in the following context: = "Concentrating efficiency" in relation to daily angles and variables such as wind speed v across the entire range of 0° to 180°.

[0176] Based on this, further considering the different sunshine hours during the day at the location of the solar thermal power plant, which are also the different daily angles of the collectors... Annual average solar radiation intensity under certain conditions The average daily total solar thermal energy collected by the collector is:

[0177] (16)

[0178] Where A is the concentrating area of ​​the solar collector.

[0179] When designing the solar collector and evaluating its concentrating efficiency, if a static value of v=0 is taken, then:

[0180] (17)

[0181] Based on the average daytime solar thermal power plant's location (latitude and longitude), the solar radiation intensity is typically around noon, approximately... A daily angle of 90° corresponds to the period with the highest weight of daytime solar radiation intensity. Therefore, at different daily angles of the solar collector, the aspect ratio in the direction of gravity varies, resulting in different amounts of sagging deformation. Therefore, the appropriate angle should be chosen. When the angle is 90°, Ed0 is maximized and optimized. Therefore, the optimal installation state for the solar collector's reflector should be... Adjust when =90°.

[0182] (2) Based on the concentrating heat collection efficiency =Maximize heat collection efficiency under all operating conditions from 0 to 180° and optimize the positional accuracy of heat collection tubes and reflectors.

[0183] Depend on

[0184] exist Interception rate at arbitrary (z, x) coordinates of the solar collector reflector under the given angle of day and wind speed v. It depends on the accuracy of the heat collector tube position. Mirror position accuracy Decide.

[0185] Therefore, to improve the efficiency of the solar collector tube under all operating conditions, the area with the highest average daily solar radiation intensity should be selected. A daily angle of 90°, i.e., the upward-facing position of the collector opening, makes... , To maximize the positional accuracy, how can we make this... =90° position , The key to maximizing positional accuracy is where its standard position is located.

[0186] During the manufacturing process of solar collector components, the structural and process dimensions of each component are realized according to the drawings. In the sub-assembly, the dimensions of each component are realized separately until the final assembly. During the final assembly, the interception rate is mainly ensured by the installation position and angle of the reflector. There is no room for adjustment in the previous manufacturing and assembly stages. Finally, the adjustment space of the reflector mounting support is used to maximize the tolerance for the cumulative error of the dimensional chain in the previous stages.

[0187] The positioning reference for calibrating the reflector is closely related to the final reference of the testing equipment. When the positioning reference of the parabolic surface testing equipment is the support bases at both ends of the solar collector, the accuracy of the parabolic surface obtained by calibrating the reflector will be determined accordingly. (Ignoring the influence of wind speed), this is the relative accuracy of the theoretical focal line based on the positioning reference of the detection equipment.

[0188] However, there is still a gap between the theoretical focal line based on the positioning reference of the testing equipment and the actual focal line (which is also the center line of the collector tube support) of the solar collector. The accuracy of the position of the heat collection tubes.

[0189] However, traditional parabolic surface inspection equipment and methods for solar collectors cannot identify the centerline (focal line) of the actual solar collector tubes. Therefore, the only solution is to maximize the manufacturing precision of the solar collector components and the precision of each assembly stage to reduce the cumulative dimensional chain error between the centerline of the solar collector tubes and the positioning reference of the parabolic surface inspection equipment during the final assembly stage, thereby improving the positional accuracy of the solar collector tubes. However, this error cannot be eliminated through calibration during the final assembly and testing process.

[0190] Therefore, in When the angle is 90°, the position of the parabolic reflector of the solar collector is detected by the parabolic surface detection equipment. Based on a certain positioning reference of the detection equipment, the position parameters of the reflector mounting point are obtained and then adjusted to the optimal position. However, there is no room for adjustment of the positional deviation between the center line of the solar collector tube and the parabolic surface detection equipment, which is also an important reason affecting the interception rate.

[0191] By analyzing the vectorized interception rate under all operating conditions, this problem was identified, which will help to further eliminate or mitigate the positional deviation of the heat collector tube and improve its positional accuracy. It laid the foundation.

[0192] 4. Using the actual centerline of the collector tubes as the reference for the parabolic detection equipment, precise focusing and detection are achieved.

[0193] If the detection benchmark of the parabolic reflector is positioned at the actual center line of the collector tube of the solar collector, or the center line of the mounting hole of the collector tube support, and then the position of the corresponding parabolic reflector is detected, it is equivalent to almost eliminating the positional deviation of the collector tube or controlling it within a very small range.

[0194] Therefore, by using the installation reference of the heat collection tube originating from the heat collector as the positioning reference of the parabolic reflector testing equipment, which is only 30-50mm away from its centerline, the deviation between the simulated focal line of the parabolic testing equipment and the actual centerline (focal line) of the heat collection tube can be controlled within 1mm. This can be guaranteed using conventional positioning methods. This is far smaller than the positional deviation between the simulated focal line and the actual focal line of the heat collection tube caused by several dimensional chain links, such as the sagging of the heat collector's two end support points or other positioning points to different Z-sections of the heat collector, manufacturing errors of the heat collection tube mounting bracket, and assembly errors, which are several meters long.

[0195] Therefore, by using the actual centerline of the solar collector tube as the reference for the parabolic detection equipment, the virtual focal line of the detection equipment can be precisely aligned with the actual centerline (actual focal line) of the solar collector tube. This almost eliminates the positional deviation of the solar collector tube, bringing its positional accuracy close to 100%. →100%.

[0196] 5. Utilizing the function of the focal ray parabolic surface detection equipment

[0197] The parabolic reflector of the solar collector is inspected using a focal ray. The basis of this inspection is to accurately focus the simulated focal ray source on the center of the installation reference of the heat collection tube support of each solar collector to be inspected, which is the actual center line of the heat collection tube and the actual focal line of the parabolic surface. Based on this, the position and angle of each mounting support of the reflector are inspected and adjusted using the focal ray, so that the parabolic surface of the corresponding reflector after installation satisfies the parabolic equation requirements of the simulated focal line from the ray source.

[0198] The parabolic surface accuracy and calibrated parabolic surface performance obtained through this testing almost tolerate cumulative deviations in the dimensional chain of all installation and manufacturing stages of the solar collector. It even simplifies the assembly process, improves assembly efficiency, and significantly enhances concentrating efficiency. Specific benefits include:

[0199] (1) The focal ray parabolic surface detection equipment enables the simulated parabolic focal line to be accurately focused with the actual focal line of the solar collector, which greatly improves the detection accuracy of the parabolic surface.

[0200] Because of precise focusing, the reflector is tested using the actual centerline of the solar collector tube as the focal line. This is equivalent to tolerating the cumulative dimensional deviations of a series of installation and manufacturing processes related to the installation reference of the solar collector tube mounting bracket. Then, the reflector is adjusted using this as the parabolic focal line reference. Thus, the testing and adjustment only target the accuracy of the reflector relative to the actual focal line, and are not affected by deviations in the solar collector support structure. The final accuracy is mainly affected by the accuracy of the testing equipment itself and the manufacturing accuracy of the reflector's profile, which can significantly improve the parabolic accuracy of the parabolic mirror relative to the actual focal line.

[0201] (2) Reduce the precision requirements for the manufacturing and assembly of solar collectors.

[0202] Because the focal ray parabolic surface inspection equipment achieves precise focusing, ultimately, as long as the installation position and angle of the reflector are adjusted, it is almost unrelated to the manufacturing and assembly precision of the various components of the solar collector. All components can be "matched" in the final stage, achieving a "fault-tolerant" effect. Therefore, there is no need to impose excessively high requirements on the assembly precision of the solar collector's components and processes, thereby reducing costs and saving labor time.

[0203] (3) The focal ray parabolic surface inspection equipment can perform real-time inspection during the assembly process, reducing the need for separate hoisting and inspection, saving assembly time, saving assembly space, improving assembly efficiency, and reducing assembly time.

[0204] (4) Significantly improve the light concentration efficiency of the solar collector.

[0205] The focal ray parabolic detection equipment not only significantly improves the light interception rate, but also significantly improves the light concentration rate, making the reflected light more concentrated near the focal line and away from the edge of the heat collection tube.

[0206] (5) Significantly improve the interception rate of the solar collector under all operating conditions and external disturbances such as wind speed.

[0207] Because the precise focusing detection of the focal ray parabolic surface detection equipment significantly improves the concentration rate, the reflected light is more concentrated near the focal line and away from the edge of the collector tube. Therefore, in actual use, when the collector sag changes under different daily angles θ and wind speed interference causes the collector tube and reflector to deviate from the optimal position, the reflected light from the parabolic reflector is still not easily deviated from the edge of the collector tube. This is because the high concentration rate gives the collector tube sufficient tolerance space, improving its robustness against interference and facilitating the improvement of the vectorized interception rate under all operating conditions, thereby improving the overall concentration rate of the solar thermal power plant.

[0208] (6) Reduce the diameter of the heat collection tube to lay the foundation for technical routes such as molten salt tanks to increase the heat collection temperature.

[0209] Due to the precise focusing and detection of the focal ray parabolic detection equipment, the light concentration rate is significantly improved, causing the reflected light to move further away from the edge of the heat collector tube. This lays the foundation for a substantial reduction in the diameter of the heat collector tube. Even with a reduction in the diameter of the heat collector tube, the interception rate is almost unaffected, and the vectorized interception rate under all operating conditions in windless conditions is not affected. The main impact is on the anti-interference capability of the heat collector under wind speed conditions, which leads to a decrease in the vectorized interception rate under all operating conditions. However, the decrease is limited and much smaller compared to the significant reduction in heat dissipation of the heat collector tube after the heat collector tube has heated up, which would be caused by reducing the tube diameter. A detailed analysis follows.

[0210] Based on the trend that the heat loss of vacuum solar collectors increases at an accelerating rate with increasing collector temperature, taking a heat transfer oil collector temperature of 400℃ as an example, the average heat loss of each loop during the concentrating heat collection stage is equivalent to approximately 120–180 W / m from 297℃ to 393℃.

[0211] Taking a molten salt bath with a heat collection temperature of 560℃ as an example, the average heat loss of each loop during the concentrating heat collection stage is equivalent to approximately 300-380 W / m² from 300℃ to 560℃. , specifically Figure 17 .

[0212] Figure 17 Heat loss ws of collector tubes in a parabolic trough solar thermal power plant as a function of temperature

[0213] The horizontal axis represents the temperature T (°C) of the heat collector tube, and the vertical axis represents the heat dissipation w (w / m) per meter of the heat collector tube.

[0214] Taking a parabolic reflector trough with an opening B of 6–8 m as an example, and assuming an average solar radiation intensity of Ws = 200–300 W / m² (this parameter can be updated according to the solar radiation intensity corresponding to the latitude and longitude of the target project), the heat collected per meter of the heat collector tube is calculated as follows.

[0215] (18)

[0216] The heat loss rate of the heat collection tube in the 393℃ heat transfer oil bath is... :

[0217] (19)

[0218] 560℃ Molten Salt Tank Heat Collector Heat Loss Rate :

[0219] (20)

[0220] If we take the turbine power generation efficiency of a solar thermal power plant corresponding to a heat collection temperature of 393℃ as an example... =40%

[0221] If we take the turbine power generation efficiency of a solar thermal power plant corresponding to a collector temperature of 560℃ as an example... =45%

[0222] If we take from equation (19) 10%, taken from equation (20) =20%, then the corresponding change in overall efficiency

[0223] =(1- ) =(1-10%)×40%=36%

[0224] =(1- ) =(1-20%)×45%=36%

[0225] That is, by increasing the heat collection temperature, the turbine power generation efficiency increases by (45-40)% / 40%=12.5% ​​compared to the previous period. However, due to the increase in heat collection temperature, the heat loss caused by the sharp increase in heat loss of the heat collection tube almost offsets the 12.5% ​​increase, and the overall efficiency hardly increases. In other words, the increase in heat collection temperature (heat transfer oil tank → molten salt tank) increases the heat-to-electricity power generation efficiency by 12.5%, but the decrease in light-to-heat efficiency due to heat loss of the heat collection tube almost offsets it.

[0226] The heat loss per meter of the collector tube in the above calculation data is determined to change with temperature. It increases sharply as the temperature rises, and the amount should be 10%→20%, with an error of no more than 6%. The specific value can be further quantified based on the actual measurement data of different collector tube manufacturers.

[0227] The intensity of sunlight can be further quantified based on the latitude and longitude of the project site, but the error will not exceed 30%. Therefore, the calculation results obtained from this method are reliable for qualitative analysis.

[0228] Conclusion Analysis: Taking all factors into consideration, the possible calculation errors mentioned above will not affect the conclusion of the calculation analysis. That is, increasing the heat collection temperature can effectively improve the thermoelectric conversion efficiency of the solar thermal power plant, but the heat loss of the heat collection tube increases sharply. If the heat loss of the heat collection tube is not addressed, it will be almost counterproductive or the benefits will be too small.

[0229] To address the issue of reducing heat loss after the heat collector tubes heat up, solutions can be found by adjusting the heat exchange methods, such as radiation, conduction, and convection, or by increasing the heat dissipation area.

[0230] If the diameter of the heat collection tube is reduced by half, its heat dissipation area will also be reduced by half. Therefore, based on the aforementioned molten salt bath heat collection temperature of 560℃, the heat loss under the same tube diameter will be reduced from... =10% increased to =20%, in contrast, if the diameter of the heat collection tube of the molten salt tank is reduced by half, the heat loss can still remain unchanged at 10%. Thus, the light-to-heat efficiency in the overall efficiency remains unchanged, while the heat-to-electricity efficiency is only affected and increased by 12.5%, which makes the molten salt tank feasible in terms of overall efficiency.

[0231] Therefore, only by significantly improving the solar collector's focusing efficiency through a focal ray parabolic detection device can the diameter of the solar collector tube be reduced without affecting the interception rate, thus offsetting the heat loss caused by the increased heat dissipation intensity of the solar collector tube after raising the solar collector temperature, making molten salt tanks or solar collectors possible.

[0232] Example 3

[0233] This implementation example Figure 5-2 As shown, the scale 2 has a transparent dial.

[0234] A camera imaging system 5 is further installed on the upper side of the solar collector. During detection, the rays from the X-ray source are reflected by the reflector seat 7 or the reflector to form a light spot on the scale 21. The camera imaging system 5 can image each scale 21 of the scale and the projected light spot. The image recognition data processing system identifies the coordinate position of the light spot on the scale, calculates the deviation of the reflector mounting bracket 02, and obtains the recommended adjustment target value of the reflector mounting bracket 02. The reflector mounting bracket 02 is then adjusted accordingly.

[0235] Example 4

[0236] This implementation example Figure 5-1As shown, a reflector 22 is set on the upper side of each transparent dial 21 at an angle of 45-90° to the dial and facing the axial side of the keel 3. The camera imaging system 5 is set on the upper side of one end of the keel. In this way, the imaging system 5 can reduce the installation height, reduce the wide-angle angle, and improve the resolution.

[0237] Setting up the reflector 22 makes the imaging angle of the imaging system 5 more reasonable, avoids the far-end dial 21 having too small an imaging angle, and reduces the front-to-back resolution. The reflector makes the imaging angle of the dial 21 more vertical, thereby improving the resolution.

[0238] Example 5

[0239] In this embodiment, the scale 21 is set as a sensitive material for the radiation from the radiation source 1, such as a photosensitive material, and the coordinate position of the target hit by the light spot can be converted into an electrical signal with position coordinate characteristics. The electrical signal is transmitted to the data processing system to calculate the deviation of the position coordinates from the standard position and to calculate the recommended adjustment value of the reflector mounting bracket 02.

[0240] Example 6

[0241] This implementation example Figure 8-1 and Figure 8-2 As shown, a temporary nut clamp 9 is installed at the outer thread of the collector tube fixing bolt 07. The nut clamp has a positioning groove 91, and the inner radius of the groove is... Furthermore, the groove is provided with a first V-shaped opening 92, the width of which is greater than the thickness of the keel mounting base 31, so that when the testing equipment is installed, there is a fault-tolerant guide space in the x-axis direction, making it easier for the keel mounting base 31 to be installed into the groove of the precisely positioned nut clamp 9.

[0242] Furthermore, the width of the positioning groove 91 is made the same as the thickness of the keel mounting base 31, so that after the mounting base 31 is introduced through the first V-shaped opening 92, it is precisely positioned inside the nut clamp 9 of the nut clamp 9, achieving precise positioning in the x-axis direction.

[0243] Furthermore, the keel mounting base 31 adopts a V-shaped opening. The upper shape of the V-shaped opening is the same as the axial cross-sectional shape of the positioning groove 91 of the nut clamp 9, both of which adopt a circular structure. At the same time, the width of the V-shaped opening is greater than the axial diameter of the positioning groove 91 of the nut clamp 9, so that the keel mounting base 31 has a fault-tolerant guide space in the z-axis direction, which is easy to install and position in the z-axis direction. After the keel 3 is lowered, the keel mounting base 31 is accurately guided into the groove shaft of the nut clamp 9, realizing accurate installation in the z-axis direction.

[0244] Furthermore, the groove shaft of the nut clamp 9 and the upper side of the V-shaped opening of the keel mounting base 31 are matched with a circular mounting surface that uses a magnetic adsorption structure to attract each other. This makes it easier for the keel mounting base 31 to achieve magnetic adsorption and centering of the groove of the nut clamp 9 during installation. After installation and positioning, the connection is also more secure and less likely to be loosened.

[0245] Example 7

[0246] like Figure 6 As shown, the testing equipment is equipped with a hoisting structure 93, which consists of slings or lugs used to lift and install the testing equipment. Its camera imaging system is mounted on the hoisting structure 93 directly above the testing equipment.

[0247] The keel and scale of the testing equipment are made of lightweight alloy or carbon fiber. Taking the spacing of the heat collection tube mounting bracket 04 of a 4-meter-long heat collector as an example, and the heat collector opening as 6 meters, the testing equipment is about 4 meters long and the scale is about 5 meters wide. The total weight can be controlled between 10-30 kg.

[0248] If a 15-30 kg testing device is installed on the four collector tube mounting brackets of the solar collector, it will further cause the solar collector to sag and deform, thus affecting the testing accuracy.

[0249] To eliminate the influence of the self-weight of the aforementioned testing equipment, a helium balloon 94 is installed on the hoisting structure 93, so that the air buoyancy of the helium balloon 94 is similar to that of the testing equipment, thereby reducing the gravitational influence of the testing equipment on the solar collector.

[0250] Example 8

[0251] The difference between this embodiment and embodiment 8 is that the buoyancy F of the helium balloon 94 is made slightly greater than the mass of the detection device, and symmetrical left and right tension cables are added at the hoisting structure 93 to suspend a counterweight mass block 100. Figure 10 As shown.

[0252] For example, if the mass of the testing equipment is m=30Kg, then the buoyancy of the helium balloon should be F=35 Kgf, and at the same time, the helium balloon should be set... =7 kg counterweight mass 100, traction helium balloon 94.

[0253] When Figure 10 In this state, the force exerted by the helium balloon on the 94 detection equipment Kgf indicates the force exerted by the testing equipment on the collector tube support of the solar collector. The deformation caused by this force to the collector is negligible, and the testing equipment is positioned on the collector tube support by gravity for testing.

[0254] When one unit is tested and the next unit is moved to, two people can lift the counterweight block 100, and the buoyancy of the helium balloon can lift the testing equipment. After moving to the next unit, the counterweight block 100 is gradually lowered. During this process, the keel mounting base is positioned and centered in the positioning groove of the nut clamp 9 of the heat collector tube mounting bracket, so as to achieve precise focusing and testing.

[0255] Example 9

[0256] This embodiment describes how to use the testing equipment.

[0257] 1. Adjust the daily angle of the solar collector to a horizontal direction with the parabolic opening facing 0° or 180°, so that the mounting bracket 04 of the solar collector tube is in a lower and easier-to-operate position.

[0258] 2. Assemble the nut clamps 9 one by one onto the outer studs of the collector tube mounting bolts 07. There is no need to change the state of the collector tubes fixed on the inner side of the mounting bolts 07. After installation, use measuring tools to calibrate the position of the two nut clamps 9 in the x-axis direction of each pair of collector tube 03 installation sections, so that they are in a symmetrical position on the center line of the collector tube 03, and the distance between the inner shafts of the positioning grooves of the left and right nut clamps 9 reaches the specified length, that is, the same as the left and right distance of the keel mounting base 31.

[0259] In fact, tightening the nut clamp 9 to the collector tube mounting nut 08 basically meets the requirements. Checking the spacing of the nut clamp 9 is to prevent the external spacing of individual mounting nuts 08 from exceeding the tolerance, which would cause the spacing of the nut clamp 9 to exceed the tolerance.

[0260] 3. To more effectively adjust the spacing of the nut clamp 9, a positioning thin nut 95 is installed between the nut clamp 9 and the collector tube mounting nut 08 to adjust the x-axis position of the nut clamp 9 to the standard position, and then the positioning thin nut 95 is tightened between the nut clamp 9 and the nut clamp 9 to fix it.

[0261] 4. After all the nuts and clamps 9 of the collector tubes to be tested are installed in place (for example, all 20-40 collector tubes of a whole collector circuit are installed in place), the angle of the collector circuit is adjusted to 90° with the opening facing upwards day by day.

[0262] 5. The detection equipment, including the helium balloon 94 and the counterweight mass block 100, is as follows: Figure 10 The testing equipment is lifted by a horizontally suspended counterweight, which causes the helium balloon 94 to lift the testing equipment and raise it to the upper side of the heat collector tube to be tested, bringing the four keel mounting bases 31 of the testing equipment close to the four nut clamps 9 on the four mounting bolts 07 of the heat collector tube to be tested.

[0263] 6. Gradually lower the counterweight block 100 so that the keel mounting base 31 of the testing equipment, which is directly above the solar collector being tested, aligns with the nut clamp 9 as it falls. This is because the nut clamp 9 has a first V-shaped opening 92, and the keel mounting base 31 has a second V-shaped opening 311 (e.g., ...). Figure 9-2 This allows the mounting base 31 and the nut clamp 9 to be automatically aligned without needing precise alignment in the x-axis and z-axis directions. Then, by further lowering the counterweight block, the magnetic adsorption structure of the keel mounting base 31 and the nut clamp will quickly attract and fall into the positioning groove 91 of the nut clamp 9, achieving precise positioning. This completes the installation, positioning, and focusing of the testing equipment and the solar collector.

[0264] 7. Using the measurement data transmitted from the level of the testing equipment (either the level is set on the testing equipment itself or a new level is installed) to the data processing system, check whether the level of scale 2 meets the requirements. If it does not meet the requirements, find the cause: (1) check the influence of the daily angle deviation of the collector opening; (2) check the influence of the out-of-tolerance of the collector tube mounting bolt 07. Eliminate the above-mentioned collector drive deviation and collector tube installation deviation.

[0265] 8. Further, based on the deviation between the coordinate position of the ray spot reflected by the reflector to the scale dial of the ray source 1 and the origin of the scale dial, the data processing system checks whether the ray spot coordinate value is within the allowable deviation range, and calculates the suggested adjustment size of the reflector mounting support 02 corresponding to the ray spot that exceeds the deviation.

[0266] 9. Adjust the dimensions according to the recommendations of the reflector mounting base 02, adjust the reflector to the standard state, and check again or in real time whether the corresponding light spot reflects to the position of the scale 21 and meets the allowable deviation. This means that the installation requirements have been met and the installation and adjustment of the reflector of the collector tube corresponding to it has been completed.

[0267] 10. Lift the counterweight block 100, use the helium balloon 94 to lift the testing equipment, move it to the corresponding collector reflector unit of the adjacent collector tube to be tested, repeat the above testing and adjustment process to complete the adjustment of the entire collector circuit.

[0268] 11. Adjust the angle of the collector circuit to the horizontal opening state every day, remove the nut clamp 9 and the positioning nut in sequence, and then move to the next collector for testing. Repeat the above testing and adjustment process.

[0269] Example 10

[0270] The difference between this embodiment and embodiment 10 is that the testing equipment is hoisted, centered, and moved into place using a mechanical boom.

[0271] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, this utility model will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by this utility model.

[0272] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A focal-area parabolic surface inspection device, comprising a radiation source (1), a scale (2), and a frame (3), characterized in that, The rays or their extensions from the X-ray source (1) pass through the focal point of the parabolic surface to be detected. A scale (21) corresponding to the X-ray source (1) is set on the scale (2). The X-ray source (1) and the scale (2) on the same parabolic surface are connected and fixed by a bracket (11). The bracket (11) and the X-ray source (1) constitute a "focal X-ray parabolic detection unit (10)". The focal X-ray parabolic detection units (10) are arranged parallel to each other and perpendicular to the keel (3). Among them, the X-ray source support (11) of each focal X-ray parabolic detection unit (10) is divided into two symmetrical groups, and the distance between the inner left and right sides of the two groups of X-ray source supports (11) is greater than or equal to the outer diameter of the heat collection tube of the parabolic heat collector being tested.

2. The focal ray parabolic surface detection device according to claim 1, characterized in that: The keel (3) is provided with keel mounting seats (31) at both ends of its length direction. The length L between the keel mounting seats (31) at both ends of the length direction of the keel (3) is the same as the spacing between the mounting brackets (04) of the heat collection tube of the parabolic reflector heat collector being tested. Two keel mounting seats (31) are provided on the left and right sides of each end of the length direction.

3. The focal ray parabolic detection device according to claim 2, characterized in that: The stiffness between the two ends of the keel mounting base (31) in the length direction of the parabolic test equipment is the same as the stiffness of the heat collection tube of the parabolic trough collector being tested.

4. The focal ray parabolic surface detection device according to claim 1, characterized in that: The number and spacing of the focal ray parabolic detection units (10) on the keel (3) are the same as the number and spacing of the cross-section of the reflector mounting support (02) of the trough parabolic reflector collector to be tested, and they are located on the same parabolic cross section.

5. The focal ray parabolic surface detection device according to claim 1, characterized in that: The scale (2) has the same number of dials (21) as the X-ray source (1), and the origin of the dial (21) is located on the path of the parallel line reflected by the parabolic reflector from the focal point of the cross-sectional profile of the parabolic surface to be detected.

6. The focal ray parabolic detection device according to claim 1, characterized in that: The scale (2) has a transparent structure with a reflector (22) at an angle of 45°-90° to the scale on the upper side of each scale (21) and facing the axial side of the keel (3).

7. The focal ray parabolic surface detection device according to claim 6, characterized in that: A camera imaging system (5) is installed on the upper side of the keel end facing the reflector (22).

8. The focal ray parabolic detection device according to any one of claims 1-7, characterized in that: The material of the dial (21) is the same as the radiation-sensitive material of the radiation source (1), which can convert the coordinate position of the radiation hitting the dial (21) into an electrical signal and transmit it to the data processing system to calculate the deviation from the origin of the dial (21).

9. The focal ray parabolic surface detection device according to claim 7, characterized in that: The camera imaging system (5) can capture the light spot hit by the scale (21) on the scale and the X-ray source (1), and identify the target coordinate position of the light spot on the scale (21) through the image recognition data processing system, and then calculate the deviation of the reflector mounting bracket (02) to obtain the recommended value of the adjustment height of the reflector mounting bracket (02).

10. The focal ray parabolic surface detection device according to claim 1, characterized in that: A nut clamp (9) is installed on the collector tube fixing bolt (7). The nut clamp (9) is provided with a positioning groove (91) and a first V-shaped opening (92). The width of the positioning groove (91) is the same as the thickness of the keel mounting base (31).

11. The focal ray parabolic surface detection device according to claim 10, characterized in that: The keel mounting base (31) adopts a V-shaped opening. The upper shape of the V-shaped opening is the same as the shape of the positioning groove (91) of the nut clamp. The width of the V-shaped opening is greater than the width of the positioning groove (91) of the nut clamp (9).

12. The focal ray parabolic surface detection device according to claim 1, characterized in that: The upper part of the testing equipment is equipped with a hoisting structure (93), which is a sling or a lug.

13. The focal ray parabolic detection device according to claim 12, characterized in that: A helium balloon (94) is installed on the hoisting structure (93), and the air buoyancy of the helium balloon (94) is similar to the weight of the detection equipment.

14. The focal ray parabolic surface detection device according to claim 10 or 11, characterized in that: A positioning thin nut (95) is set between the nut clamp (9) and the collector tube mounting nut (08).

15. The focal ray parabolic surface detection device according to claim 13, characterized in that: The helium balloon (94) is equipped with a traction cable, and a counterweight mass block (100) is suspended on each side.

16. The focal ray parabolic detection device according to claim 13, characterized in that: A level is installed on the detection equipment, and the signal is connected to the data processing system.

Images