Flue gas flow velocity measurement system and method based on asymmetric arrangement of three-dimensional pitot tubes

Abstract

The invention discloses a flue gas flow velocity measurement system and method based on asymmetric arrangement of three-dimensional pitot tubes, and belongs to the technical field of flow velocity measurement. The method comprises the steps that multiple sets of three-dimensional pitot tubes are adopted to form a measurement array, the measurement array is divided into a center layer, a transition layer and a wall face layer in the radial direction, and probes of all the layers are arranged at intervals in the circumferential direction and arranged front and back in the axial direction; each probe is internally provided with a temperature sensor and a flue gas extraction opening, and the flue gas density can be periodically and automatically corrected; the average flow velocity of the fluid is obtained through weighted averaging of data collected by all the probes, backflow in a complex flow field is recognized in combination with a neural network algorithm and a machine learning algorithm, and simple prediction of the flow velocity and the flow direction of the fluid is achieved. According to the invention, the problems of insufficient precision and poor adaptability of traditional symmetrically arranged pitot tubes in complex flow field measurement are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fluid measurement, and particularly relates to a flue gas flow rate measurement system and method based on asymmetric arrangement of three-dimensional pitot tubes. BACKGROUND

[0002] In the field of industrial production and environmental protection monitoring, accurate measurement of flue gas flow rate is a key link for evaluating combustion efficiency and controlling pollutant emissions.

[0003] In traditional flue gas flow rate measurement technology, pitot tubes are widely used due to their simple structure and low cost, but their measurement accuracy and flow field adaptability have obvious limitations. Symmetrically arranged pitot tube arrays are prone to incomplete capture of flow field information due to insufficient uniformity of measurement point distribution, especially when there is a large difference in flow rate between the center of the pipe and the wall area, making it difficult to truly reflect the overall flow field characteristics, and the measurement error is often large.

[0004] Secondly, axial arrangement in the same plane cannot effectively capture the axial non-uniform characteristics such as backflow and vortex in the flow field, and has weak recognition ability for counterflow components, making it difficult to meet the demand for high-precision monitoring.

[0005] On the other hand, existing pitot tubes rely on a single pressure signal to calculate flow rate, without considering the influence of dynamic changes in flue gas temperature, density and other parameters on the measurement results, resulting in further decline in accuracy under complex conditions such as high temperature and dust. In addition, traditional data processing methods can only achieve simple calculation of real-time flow rate, and lack the ability to identify and predict abnormal flow patterns such as vortex and backflow in complex flow fields, making it difficult to meet the demand for dynamic monitoring and early regulation of flue gas flow field in modern industry. SUMMARY

[0006] Based on the problems of insufficient accuracy and poor adaptability of existing symmetrically arranged pitot tubes in complex flue gas flow field measurement, and the difficulty in considering dynamic parameter correction and flow field characteristic analysis, the present application provides a flue gas flow rate measurement system and method based on asymmetric arrangement of three-dimensional pitot tubes, which realizes high-precision measurement and dynamic characteristic identification of complex flow field by optimizing the spatial arrangement of probes, integrating multi-parameter measurement function and introducing intelligent algorithm.

[0007] To achieve the above purpose, the present application adopts the following technical solutions:

[0008] The flue gas flow rate measurement system based on asymmetric arrangement of three-dimensional pitot tubes comprises a measurement device, a control device, a flue gas density measurement device and a data processing device.

[0009] The measurement device is composed of multiple groups of three-dimensional pitot tubes, and the pitot tube probes are arranged in an asymmetric staggered manner in the flue duct, with a front-back position difference in spatial scale, for collecting flow rate raw data.

[0010] The control device is used for controlling the measurement timing of each pitot tube probe measuring circuit in the measuring device and the on-off of the flue gas extraction circuit, so as to control the synchronization or periodicity of data acquisition, and simultaneously receiving instructions from the data processing device to realize real-time adjustment of the measurement frequency;

[0011] The flue gas density measuring device is used for obtaining real-time temperature data of the flue gas and calculating the flue gas density, and feeding back to the data processing device to provide temperature and density correction parameters for a flow rate calculation module in the data processing device;

[0012] The data processing device is used for receiving and storing the flow rate raw data and the flue gas density data from the measuring device and the flue gas density measuring device, and then comprehensively processing all the data to perform flow rate calculation, weighted average, flow field modeling and prediction, and feeding back control instructions to the control device to realize adaptive measurement period adjustment.

[0013] The further improvement of the present application is that the measuring device divides the probes of the three-dimensional pitot tube into a center group, a transition group and a wall group along the radial direction of the flue; the probes of each group are arranged around the central axis of the flue with the axial direction of the flue as the center, and the probes of the center group are relatively in front in the axial direction, the probes of the transition group are second, and the probes of the wall group are last; according to the accuracy requirement of measurement, the number of probes of each group is 3-6.

[0014] The further improvement of the present application is that according to the accuracy requirement of measurement, the interval angle of the three-dimensional pitot tube probes of the center layer, the transition layer and the wall layer in the circumferential direction is between 30°-120°, and the probes of adjacent layers do not overlap in the circumferential projection, forming an interlaced distribution measurement grid; in the radial direction, the distance of the probes of the center layer from the central axis of the pipeline is 1 / 4 of the pipeline radius, the distance of the probes of the transition layer is 2 / 4 of the pipeline radius, and the distance of the probes of the wall layer is 3 / 4 of the pipeline radius, so as to ensure the coverage of different flow rate gradient regions; in the axial direction, the probes of different layers are arranged with a front-back difference of 10-30 cm in the axial direction, the front probes are deviated to the flow direction, and the rear probes are deviated from the main flow direction by 5-10°, so as to simultaneously capture the components of the forward flow and the backflow.

[0015] The further improvement of the present application is that the spacing and angle of the probes at different positions in each direction are adjusted according to the length and diameter of the pipeline, and the adjustment of each probe satisfies that the measurement coverage areas of any two probes in the flow field do not overlap and have no obvious blind area, and the coverage area is not less than 85% of the cross-sectional area of the pipeline.

[0016] The further improvement of the present application is that for the rectangular pipeline, according to the characteristics of the cross-sectional shape, the probes of each layer are arranged in a rectangular shape on the cross section, and at least 4 probes are arranged in each layer and located at the four corners of the rectangular cross section; when the length and width of the pipeline are greatly different, the number of probes can be increased in the length or width direction to form a more dense array of measurement points.

[0017] The further improvement of the present application is that the probe of the three-dimensional pitot tube is arranged with a flue gas extraction port and a temperature sensor and connected with a flue gas density measuring device, which can collect the temperature and flue gas density data at the position of the probe at regular intervals and transmit them to the data processing device for correction of the fluid density.

[0018] The further improvement of the present application is that one end of the flue gas density measuring device is connected with the flue gas extraction port on each pitot tube probe through a corrosion-resistant air extraction pipeline, and the other end is connected with the data processing device; an independent electromagnetic valve is arranged on the pipeline between the flue gas extraction port on each probe and the flue gas density measuring device, and the electromagnetic valve is connected with a control unit, which sends on-off instructions according to pre-set or input to realize the on-off of each probe circuit.

[0019] The further improvement of the present application is that the control device is composed of an electromagnetic valve group, a pressure transmitter and a controller, wherein the electromagnetic valve group contains an electromagnetic reversing valve corresponding to each three-dimensional pitot tube probe, the input end of each electromagnetic reversing valve is connected to the total pressure hole and the static pressure hole of the corresponding probe through a pressure-resistant hose, and the output end is connected to each pressure transmitter, and the pressure transmitter adopts a high-precision differential pressure structure.

[0020] The further improvement of the present application is that the data processing device includes a data receiving module, a data storage module, a data operation module and a result output module; the data receiving module receives the raw data of flow rate collected by the measuring device and the flue gas density data transmitted by the flue gas density measuring device; the data storage module is used for storing the collected raw data and processed data; the data operation module has a data analysis model built based on neural network algorithm and machine learning algorithm, which processes the collected data; and the result output module outputs the average flow rate, flow rate distribution and flow field characteristics obtained by operation in a graphical interface.

[0021] The flue gas flow rate measuring method based on the asymmetric arrangement of three-dimensional pitot tubes, which is based on a flue gas flow rate measuring system based on the asymmetric arrangement of three-dimensional pitot tubes, comprising:

[0022] S1, each pitot tube is calibrated in a standard wind tunnel, and the reference parameters of the three-dimensional pitot tube are calibrated according to the standard in the Technical Specification for Continuous Monitoring of Carbon Dioxide Emissions from Flue Gas in Thermal Power Plants;

[0023] S2, all pitot tube probes are arranged in an asymmetric manner in the flue duct;

[0024] S3, according to the measurement needs, the pressure values at the respective probes are measured respectively, and the measured original pressure data are sent to a data processing device through a signal transmission link, and the data are classified and stored in a preset database according to time by the data processing device; a fixed measurement period is set, and the period is adaptively adjusted in a range of 1-60 minutes according to the flue gas working condition, and the measurement operation is continuously performed according to the period, so that a flue gas flow field pressure data set containing different time nodes is formed in the database;

[0025] S4, in the data processing device, the air flow velocity, the pitch angle and the yaw angle at the measuring point are calculated according to the relationship between the pressure difference and the velocity; according to the measurement results of the respective points, the weighted average of the data collected by the respective probes is obtained to obtain the average flow velocity of the fluid, the basic weight coefficient of the center layer probe is set to 1.0 because the center layer probe is located in the core area of the flow field; the basic weight coefficient of the transition layer probe is set to 0.9; the weight coefficient of the wall group probe is set to 0.8 because the wall group probe is affected by the boundary layer;

[0026] S5, the neural network algorithm and the machine learning algorithm in the data operation module are combined with the original data set in the database to perform model training, and the vortex and backflow positions in the flow field are identified according to the flow velocity value, the pitch angle, the yaw angle and the probe spatial coordinate from the data of the respective probes;

[0027] S6, after the system is continuously operated for more than 3 months or accumulates not less than 100,000 groups of effective data, a historical database is established through the storage module of the data processing device; on the basis of the historical database, the parameters of the model are adjusted through multiple rounds of training, and the model optimization is completed when the prediction error is stabilized within ±3%; thereafter, incremental training is performed every 10,000 groups of new data to ensure long-term prediction effectiveness and realize dynamic prediction of the flow field.

[0028] Compared with the prior art, the present application has at least the following beneficial technical effects:

[0029] 1) Improve the measurement accuracy of complex flow fields: through the asymmetric staggered arrangement of the three-dimensional Pitot tube array, full coverage of different flow velocity gradient areas in the flue is realized, the measurement blind area is reduced, and the present application is especially suitable for complex flow fields containing backflow and vortex, and solves the problem that the traditional symmetrically arranged probes cannot fully capture the non-uniform flow field.

[0030] 2) Realize dynamic parameter correction: the temperature sensor and the flue gas extraction port are arranged in the system, the temperature and density data can be collected in real time, the calculation results of the flow velocity are dynamically corrected by combining the fluid mechanics formula, and the measurement error under complex working conditions such as high temperature and dust is reduced.

[0031] 3) Intelligent analysis of flow field: through neural network and machine learning algorithm, multiple sets of measurement data are trained to identify abnormal flow state (such as backflow, vortex) in flow field, and short-term flow field prediction is realized based on historical data, providing advance for industrial process control. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0033] Figure 1 It is a structural schematic diagram of flue gas flow velocity measurement system based on three-dimensional Pitot tube asymmetric arrangement.

[0034] Figure 2 It is a schematic diagram of the circular probe at the front end of the three-dimensional Pitot tube.

[0035] Figure 1 The middle mark is:

[0036] 1. Pitot tube probe; 2. Temperature sensor; 3. Flue gas extraction port; 4. Control device; 5. Solenoid valve; 6. Flue gas density measurement device; 7. Flue gas pipeline; 8. Data processing device.

[0037] Figure 2 The middle mark is:

[0038] α: pitch angle; β: yaw angle; γ: represents the position of the center hole of the measuring hole distance, which is 45°; q: dynamic pressure of incoming flow incidence direction (r direction); P i (α, β): probe hole pressure, i = 1-5. DETAILED DESCRIPTION

[0039] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are considered to be exemplary in nature rather than limiting.

[0040] In the description of the application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0041] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0042] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection, or communication; it can be directly connected, or indirectly connected through intermediate medium, or the communication or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] In the present application, unless otherwise specifically defined and limited, the first feature "on" or "under" the second feature can include the first and second features in direct contact, or the first and second features not in direct contact but in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes the first feature directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes the first feature directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0044] It should be understood that when used in the present specification and the appended claims, the terms "include" and "contain" indicate the presence of the described features, whole, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, whole, steps, operations, elements, components and / or sets thereof.

[0045] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0046] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0047] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0048] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0049] Example 1

[0050] The flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement provided by the present invention includes a measuring device, a control device, a flue gas density measuring device, and a data processing device.

[0051] The measuring device consists of multiple sets of three-dimensional Pitot tubes. The Pitot tube probes are arranged in an asymmetrical staggered manner in the flue and have differences in their front and rear positions in space, which are used to collect raw flow velocity data.

[0052] The control device is used to control the measurement timing of each pitot tube probe measurement circuit and the on / off state of the flue gas extraction circuit in the measuring device, thereby controlling the synchronization or periodicity of data acquisition. Simultaneously, it receives instructions from the data processing device to achieve real-time adjustment of the measurement frequency.

[0053] The flue gas density measuring device is used to acquire real-time temperature data of flue gas and calculate flue gas density, which is then fed back to the data processing device to provide temperature and density correction parameters for the flow rate calculation module in the data processing device.

[0054] The data processing unit receives and stores raw flow velocity data and flue gas density data from the measuring device and the flue gas density measuring device. Then, it integrates all the data, performs flow velocity calculation, weighted averaging, flow field modeling and prediction, and feeds back control commands to the control device to achieve adaptive measurement cycle adjustment.

[0055] In this embodiment, the measuring device divides the probes of the three-dimensional Pitot tube into a central group, a transition group, and a wall group along the radial direction of the flue. With the flue axis as the center, the Pitot tube probes of each group are arranged around the central axis of the flue, with the probes of the central group being relatively forward in the axial direction, followed by the probes of the transition group, and the probes of the wall group being the last. Depending on the accuracy requirements of the measurement, the number of Pitot tube probes in each group is 3-6.

[0056] In this embodiment, based on the measurement accuracy requirements, the circumferential spacing angles of the three-dimensional Pitot tube probes in the central layer, transition layer, and wall layer are between 30° and 120°, and the probes of adjacent layers do not overlap in the circumferential projection, forming an interlaced measurement grid. In the radial direction, the distance between the central layer probe and the central axis of the pipe is 1 / 4 of the pipe radius, the transition layer is 2 / 4 of the pipe radius, and the wall layer is 3 / 4 of the pipe radius, ensuring coverage of different flow velocity gradient regions. In the axial direction, the probes of different layers are set with a front-to-back difference of 10-30cm, with the front probe biased towards the incoming flow direction and the rear probe biased towards the mainstream direction by 5-10°, which can simultaneously capture downstream and downstream components.

[0057] In this embodiment, the spacing and angle of the probes at different positions in each direction are adjusted according to the length and diameter of the pipe. The adjustment of each probe satisfies the following: the measurement coverage areas of any two probes in the flow field do not overlap and there are no obvious blind spots, and the coverage area is not less than 85% of the cross-sectional area of ​​the pipe.

[0058] In this embodiment, for rectangular pipes, based on the characteristics of their cross-sectional shape, the probes in each layer are arranged in a rectangular pattern on the cross-section, with a minimum of 4 probes per layer, located at the four corners of the rectangular cross-section; when the difference between the length and width of the pipe is large, the number of probes can be increased in the length or width direction to form a denser array of measurement points.

[0059] In this embodiment, the probe of the three-dimensional Pitot tube is equipped with a flue gas extraction port and a temperature sensor, and is connected to a flue gas density measuring device. It can periodically collect temperature and flue gas density data at the location of the probe and transmit them to a data processing device for fluid density correction.

[0060] In this embodiment, one end of the flue gas density measuring device is connected to the flue gas extraction port on each Pitot tube probe through a corrosion-resistant extraction pipeline, and the other end is connected to the data processing device; each probe has an independent solenoid valve on the pipeline between the flue gas extraction port and the flue gas density measuring device, and the solenoid valve is connected to the control unit. The control unit sends on / off commands according to preset or input commands to realize the on / off of the corresponding circuit of each probe.

[0061] In this embodiment, the control device consists of a solenoid valve group, a pressure transmitter, and a controller. The solenoid valve group includes solenoid directional valves that correspond one-to-one with each three-dimensional Pitot tube probe. The input end of each solenoid directional valve is connected to the total pressure port and static pressure port of the corresponding probe through a pressure-resistant hose, and the output end is connected to each pressure transmitter. The pressure transmitter adopts a high-precision differential pressure structure.

[0062] In this embodiment, the data processing device includes a data receiving module, a data storage module, a data processing module, and a result output module. The data receiving module receives raw flow velocity data collected by the measuring device and flue gas density data transmitted by the flue gas density measuring device. The data storage module stores the collected raw data and the processed data. The data processing module has a built-in data analysis model based on neural network algorithms and machine learning algorithms to process the collected data. The result output module outputs the calculated average flow velocity, flow velocity distribution, and flow field characteristics in a graphical interface.

[0063] Example 2

[0064] See Figure 1 The flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement provided by the present invention includes a pitot tube probe 1, a temperature sensor 2, a flue gas extraction port 3, a control device 4, a solenoid valve 5, a flue gas density measuring device 6, a flue gas duct 7, and a data processing device 8.

[0065] The following uses a circular pipe as an example to describe in detail the specific implementation of the present invention:

[0066] This system consists of a measuring device, a control device 4, a flue gas density measuring device 6, and a data processing device 8. Each part is connected to a signal line through pipelines to form a closed-loop measuring system.

[0067] The core of the measuring device consists of multiple sets of three-dimensional Pitot tube probes 1, with a temperature sensor 2 and a flue gas extraction port 3 installed on the upper part of the probes. The control device 4 includes a solenoid valve group, a pressure transmitter, and a controller. The input end of the solenoid valve group 5 is connected to the total pressure port and static pressure port of the Pitot tube probe 1 through a pressure-resistant hose, and the output end is connected to the pressure transmitter. The flue gas density measuring device 6 is connected to the flue gas extraction port 3 of the Pitot tube probe 1 through a corrosion-resistant extraction pipeline. The independent solenoid valve 5 on the pipeline is driven by the controller of the control device 4. The data processing device 8 is connected to the control device 4, the flue gas density measuring device 6, and the temperature sensor 2 through signal cables to realize data reception and processing.

[0068] Pitot tube probe 1 is divided into a central group, a transition group, and a wall group along the radial direction of the flue. The distance between the central group probe and the central axis of the pipe is 1 / 4 of the pipe radius, the distance between the transition group probe and the central axis is 2 / 4 of the radius, and the distance between the wall group probe and the central axis is 3 / 4 of the radius. According to the measurement accuracy requirements, n probes (3≤n≤6) are evenly arranged in the circumferential direction for each layer of probes, and n increases with the increase of measurement accuracy. In the axial direction, the probes of different layers are set with a front-to-back difference of 10-30cm.

[0069] All Pitot tube probes 1 were calibrated in a standard wind tunnel according to the "Technical Specification for Continuous Monitoring of Carbon Dioxide Emissions from Flue Gas in Thermal Power Plants," and the calibration parameters were recorded. Specifically, the theoretical basis for the calibration process is as follows: Figure 2 As shown, in a spherical coordinate system (r, angular coordinates), the pressure distribution of a three-dimensional incompressible fluid flowing over the surface of a spherical probe is modeled. Based on fluid mechanics principles, the functional relationship between the pressure at each pressure measurement point of the probe and the incoming flow parameters can be obtained, as shown in Equations 1-5:

[0070]

[0071] Where, p totle The total pressure of the incoming flow can be directly measured by the Pitot tube probe 1. Based on the above formula, a calibration curve for the Pitot tube probe 1 can be established.

[0072] The probe is fixed inside the flue gas duct 7 according to the above arrangement. The solenoid valve group 5 of the control device 4 is connected to the pressure transmitter. After zeroing, the exhaust pipe of the flue gas density measuring device 6 is connected to check whether the measurement circuit is normal.

[0073] The controller sends commands according to a preset cycle, controlling the on / off state of each probe circuit through the solenoid valve group 5. During pressure measurement, the solenoid directional valve switches to the total pressure / static pressure measurement mode, and the pressure transmitter converts the differential pressure signal into an electrical signal and transmits it to the data processing device 8. During density and temperature measurement, the flue gas extraction solenoid valve 5 is opened periodically, the flue gas density measuring device 6 calculates the density using the mass-volume method, the temperature sensor 2 synchronously collects the temperature at the measuring point, and the measurement data is uploaded to the storage module.

[0074] The data processing device 8's calculation module performs flow velocity calculation, calculates the flow velocity at each point according to the pressure difference formula, corrects the results by combining temperature and density data, and finally performs a weighted average of the measurement results to obtain the average flow velocity of the flue.

[0075] The neural network algorithm and machine learning algorithm in the data processing module of the data processing device 8 are combined with the original dataset in the database to train the model. Based on the flow velocity value, pitch angle, yaw angle and probe spatial coordinates (radial / axial position) from the data of each probe, the location of eddies and backflow in the flow field is simply identified.

[0076] After the system has continuously collected sufficient data, a historical database is established through the storage module of the data processing device 8. Based on the database, the model network parameters are adjusted through multiple rounds of training, with a focus on improving the recognition accuracy of complex flow fields. Model optimization is completed when the prediction error stabilizes within ±3%. Subsequently, incremental training is performed every 10,000 sets of new data to ensure long-term prediction effectiveness and achieve simple dynamic prediction of flow fields.

[0077] Example 3

[0078] The present invention provides a flue gas velocity measurement method based on a three-dimensional pitot tube asymmetric arrangement, comprising:

[0079] S1, each Pitot tube is calibrated in a standard wind tunnel, and the reference parameters of the three-dimensional Pitot tube are calibrated according to the standard in the "Technical Specification for Continuous Monitoring of Carbon Dioxide Emissions from Flue Gas of Thermal Power Plants".

[0080] S2, Arrange all Pitot tube probes in the flue in an asymmetrical manner;

[0081] S3, according to the measurement needs, measure the pressure value at each probe respectively, and send the raw pressure data obtained by measurement to the data processing device through the signal transmission link. The data processing device classifies and stores the data in the preset database according to time; a fixed measurement cycle is set, and the cycle is adaptively adjusted within the range of 1-60 minutes according to the flue gas conditions. The measurement operation is continuously executed according to the cycle, so that the database forms a flue gas field pressure dataset containing different time nodes.

[0082] S4, in the data processing device, the airflow velocity, pitch angle and yaw angle at the measuring point are calculated according to the relationship between pressure difference and velocity; based on the measurement results of each point, the average flow velocity of the fluid is obtained by weighted averaging of the data collected by each probe. The basic weight coefficient of the central layer probe is set to 1.0 because it is located in the core area of ​​the flow field; the basic weight coefficient of the transition layer probe is set to 0.9; and the weight coefficient of the wall group probe is set to 0.8 because it is affected by the boundary layer.

[0083] S5, in the data processing module, the neural network algorithm and machine learning algorithm are combined with the original dataset in the database to train the model. Based on the flow velocity value, pitch angle, yaw angle and probe spatial coordinates from each probe data, the location of eddies and backflow in the flow field is identified.

[0084] S6: After the system has been running continuously for more than 3 months or has accumulated no less than 100,000 sets of valid data, a historical database is established through the storage module of the data processing device. Based on the historical database, the parameters of the model are adjusted through multiple rounds of training. When the prediction error is stable within ±3%, the model optimization is completed. Thereafter, incremental training is carried out for every 10,000 sets of new data to ensure long-term prediction effectiveness and realize dynamic prediction of the flow field.

[0085] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0086] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement, characterized in that, It includes measuring devices, control devices, flue gas density measuring devices, and data processing devices; The measuring device consists of multiple sets of three-dimensional Pitot tubes. The Pitot tube probes are arranged in an asymmetrical staggered manner in the flue and have differences in front and back positions in space, which are used to collect raw flow velocity data. The control device is used to control the measurement timing of each Pitot tube probe measurement circuit and the on / off state of the flue gas extraction circuit in the measuring device, thereby controlling the synchronization or periodicity of data acquisition. At the same time, it receives instructions from the data processing device to realize real-time adjustment of the measurement frequency. The flue gas density measuring device is used to acquire real-time temperature data of flue gas and calculate flue gas density, which is then fed back to the data processing device to provide temperature and density correction parameters for the flow rate calculation module in the data processing device. The data processing unit receives and stores raw flow velocity data and flue gas density data from the measuring device and the flue gas density measuring device. Then, it integrates all the data, performs flow velocity calculation, weighted averaging, flow field modeling and prediction, and feeds back control commands to the control device to achieve adaptive measurement cycle adjustment.

2. The flue gas velocity measurement system based on asymmetric arrangement of three-dimensional Pitot tubes according to claim 1, characterized in that, The measuring device divides the three-dimensional Pitot tube probes into a central group, a transition group, and a wall group along the radial direction of the flue. With the flue axis as the center, the Pitot tube probes of each group are arranged around the central axis of the flue, with the probes of the central group being relatively forward in the axial direction, followed by the probes of the transition group, and the probes of the wall group being the last. Depending on the accuracy requirements of the measurement, the number of Pitot tube probes in each group is between 3 and 6.

3. The flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement according to claim 2, characterized in that, To meet the measurement accuracy requirements, the three-dimensional Pitot tube probes of the central layer, transition layer, and wall layer are spaced circumferentially at angles between 30° and 120°, and the probes of adjacent layers do not overlap in the circumferential projection, forming an interlaced measurement grid. In the radial direction, the distance between the central layer probe and the pipe's central axis is 1 / 4 of the pipe radius, the transition layer is 2 / 4 of the pipe radius, and the wall layer is 3 / 4 of the pipe radius, ensuring coverage of different flow velocity gradient regions. In the axial direction, the probes of different layers are set with a front-to-back difference of 10-30 cm, with the front probe biased towards the incoming flow direction and the rear probe deviating from the mainstream direction by 5-10°, enabling simultaneous capture of downstream and backflow components.

4. The flue gas velocity measurement system based on asymmetric arrangement of three-dimensional Pitot tubes according to claim 2, characterized in that, The spacing and angle of probes at different positions in each direction are adjusted according to the length and diameter of the pipe. The adjustment of each probe satisfies the following conditions: the measurement coverage areas of any two probes in the flow field do not overlap and there are no obvious blind spots, and the coverage area is not less than 85% of the cross-sectional area of ​​the pipe.

5. The flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement according to claim 2, characterized in that, For rectangular pipes, based on the characteristics of their cross-sectional shape, the probes in each layer are arranged in a rectangular pattern on the cross-section, with a minimum of 4 probes per layer, located at the four corners of the rectangular cross-section. When the difference between the length and width of the pipe is large, the number of probes can be increased in either the length or width direction to form a denser array of measurement points.

6. The flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement according to claim 2, characterized in that, The three-dimensional Pitot tube probe is equipped with a flue gas extraction port and a temperature sensor, and is connected to a flue gas density measuring device. It can periodically collect temperature and flue gas density data at the probe location and transmit them to a data processing device for fluid density correction.

7. The flue gas velocity measurement system based on asymmetric arrangement of three-dimensional Pitot tubes according to claim 2, characterized in that, One end of the flue gas density measuring device is connected to the flue gas extraction port on each Pitot tube probe via a corrosion-resistant extraction pipeline, and the other end is connected to the data processing device. Each probe has an independent solenoid valve on the pipeline between the flue gas extraction port and the flue gas density measuring device. The solenoid valve is connected to the control unit, which sends on / off commands according to preset or input commands to realize the on / off of the corresponding circuit of each probe.

8. The flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement according to claim 2, characterized in that, The control device consists of a solenoid valve group, a pressure transmitter, and a controller. The solenoid valve group includes solenoid directional valves that correspond one-to-one with each three-dimensional Pitot tube probe. The input end of each solenoid directional valve is connected to the total pressure port and static pressure port of the corresponding probe through a pressure-resistant hose, and the output end is connected to each pressure transmitter. The pressure transmitter adopts a high-precision differential pressure structure.

9. The flue gas velocity measurement system based on a three-dimensional pitot tube asymmetric arrangement according to claim 2, characterized in that, The data processing device includes a data receiving module, a data storage module, a data processing module, and a result output module; the data receiving module receives raw flow velocity data collected by the measuring device and flue gas density data transmitted by the flue gas density measuring device; the data storage module is used to store the collected raw data and the processed data. The data processing module has a built-in data analysis model based on neural network and machine learning algorithms to process the collected data; The results output module outputs the calculated average flow velocity, flow velocity distribution, and flow field characteristics in a graphical interface.

10. A method for measuring flue gas velocity based on a three-dimensional pitot tube asymmetric arrangement, characterized in that, This method, based on the flue gas velocity measurement system according to any one of claims 1 to 9, comprises: S1, each Pitot tube is calibrated in a standard wind tunnel, and the reference parameters of the three-dimensional Pitot tube are calibrated according to the standard in the "Technical Specification for Continuous Monitoring of Carbon Dioxide Emissions from Flue Gas of Thermal Power Plants". S2, Arrange all Pitot tube probes in the flue in an asymmetrical manner; S3, according to the measurement needs, measure the pressure value at each probe respectively, and send the raw pressure data obtained by measurement to the data processing device through the signal transmission link. The data processing device classifies and stores the data in the preset database according to time; a fixed measurement cycle is set, and the cycle is adaptively adjusted within the range of 1-60 minutes according to the flue gas conditions. The measurement operation is continuously executed according to the cycle, so that the database forms a flue gas field pressure dataset containing different time nodes. S4, in the data processing device, the airflow velocity, pitch angle and yaw angle at the measuring point are calculated according to the relationship between pressure difference and velocity; based on the measurement results of each point, the average flow velocity of the fluid is obtained by weighted averaging of the data collected by each probe. The basic weight coefficient of the central layer probe is set to 1.0 because it is located in the core area of ​​the flow field; the basic weight coefficient of the transition layer probe is set to 0.9; and the weight coefficient of the wall group probe is set to 0.8 because it is affected by the boundary layer. S5, in the data processing module, the neural network algorithm and machine learning algorithm are combined with the original dataset in the database to train the model. Based on the flow velocity value, pitch angle, yaw angle and probe spatial coordinates from each probe data, the location of eddies and backflow in the flow field is identified. S6: After the system has been running continuously for more than 3 months or has accumulated no less than 100,000 sets of valid data, a historical database is established through the storage module of the data processing device. Based on the historical database, the parameters of the model are adjusted through multiple rounds of training. When the prediction error is stable within ±3%, the model optimization is completed. Thereafter, incremental training is carried out for every 10,000 sets of new data to ensure long-term prediction effectiveness and realize dynamic prediction of the flow field.

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