Flue gas emission flow measuring method and system based on ultrasonic multi-sensor array

Abstract

The invention discloses a flue gas emission flow measurement method and system based on an ultrasonic multi-sensor array, and belongs to the technical field of gas flow measurement, and the method comprises the steps: arranging a plurality of ultrasonic sensors and auxiliary sensor groups in a flue; according to the basic parameters of the ultrasonic sensors and the downstream and countercurrent propagation time difference measured by the ultrasonic sensors, the gas flow rate corresponding to each ultrasonic sensor is obtained; based on the collected temperature, humidity and pressure values, correcting the gas flow velocity of the ultrasonic sensors, obtaining a gas flow velocity compensation value of each ultrasonic sensor, and compensating the gas flow velocity of each ultrasonic sensor by using the gas flow velocity compensation value; and fusing the compensated gas flow rates of all the ultrasonic sensors to obtain the fused flue gas flow rate, and obtaining the flue gas emission flow based on the fused flue gas flow rate of the flue. According to the invention, accurate metering of the flue gas flow in a complex flue gas environment can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas flow measurement, and in particular relates to a flue gas emission flow measurement method and system based on an ultrasonic multi-sensor array. Background Art

[0002] Flue gas flow measurement is a key link in environmental monitoring (such as CEMS systems). At present, the commonly used flue gas flow measurement methods mainly include the Pitot tube method, thermal mass flowmeter method, vortex flowmeter method, etc. However, these methods have some limitations in practical applications, such as measurement accuracy is easily affected by working conditions, maintenance costs are high, and dynamic real-time measurement cannot be achieved. Ultrasonic measurement technology has the advantages of non-contact, large measurement range, high accuracy, and fast response speed, and has been widely used in the field of flow measurement. However, traditional ultrasonic velocity measurement technology has the following problems:

[0003] Single-point measurement has large errors: the flow field in the flue is unevenly distributed, and single-point measurement is difficult to reflect the actual flow rate.

[0004] Sensitive to environmental interference: Dynamic changes in flue gas temperature, pressure, and humidity directly affect the sound velocity calculation, resulting in large flow velocity deviations. Summary of the Invention

[0005] In response to the deficiencies in the prior art, the present invention provides a flue gas emission flow measurement method and system based on an ultrasonic multi-sensor array, which can achieve accurate measurement of flue gas flow in complex flue gas environments.

[0006] The present invention provides the following technical solutions:

[0007] In a first aspect, a method for measuring flue gas emission flow rate based on an ultrasonic multi-sensor array is provided, comprising:

[0008] Several ultrasonic sensors and auxiliary sensor groups are arranged in the flue according to a set layout, wherein the auxiliary sensor group includes a temperature sensor, a pressure sensor and a humidity sensor;

[0009] The gas flow rate corresponding to each ultrasonic sensor is obtained based on the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the difference in propagation time between the upstream and downstream measured by the ultrasonic sensor.

[0010] Based on the temperature, humidity, and pressure values corresponding to each ultrasonic sensor, the gas flow rate of the ultrasonic sensor is corrected to obtain a gas flow rate compensation value for each ultrasonic sensor, and the gas flow rate of each ultrasonic sensor is compensated using the gas flow rate compensation value;

[0011] The compensated gas flow rates of all ultrasonic sensors are fused to obtain a fused flue gas flow rate, and the flue gas emission flow rate is obtained based on the fused flue gas flow rate.

[0012] Optionally, a plurality of ultrasonic sensors and auxiliary sensor groups are arranged in the flue in a predetermined layout; specifically:

[0013] If the flue is circular, it is divided into several concentric circles according to the equal ring area method. Each concentric circle is divided into grids with equal areas according to the number of ultrasonic sensors, and ultrasonic sensors and auxiliary sensor groups are installed in the grids accordingly.

[0014] When the flue is rectangular, it is divided into grids of equal area, and ultrasonic sensors and auxiliary sensor groups are arranged in the grids, with the ratio of the number of ultrasonic sensors on the long side to the short side of the rectangular flue being 2:1-3:1;

[0015] The distance between two adjacent ultrasonic sensors is greater than or equal to 20 mm.

[0016] Optionally, the gas flow rate corresponding to each ultrasonic sensor is obtained according to the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the downstream and upstream propagation time difference measured by the ultrasonic sensor; specifically:

[0017]

[0018] Among them, u i is the gas flow rate corresponding to the i-th ultrasonic sensor, L is the distance between the two transducers of the ultrasonic sensor, θ is the angle between the ultrasonic propagation direction of the ultrasonic sensor and the cross section of the flue, t1 and t2 are the acoustic times of the ultrasonic wave during forward and reverse propagation, respectively; τ1 and τ2 are the acoustic delays of the ultrasonic wave during forward and reverse propagation, respectively.

[0019] Optionally, based on the temperature, humidity, and pressure values corresponding to each ultrasonic sensor, the gas flow rate of the ultrasonic sensor is corrected, a gas flow rate compensation value of each ultrasonic sensor is obtained, and the gas flow rate of each ultrasonic sensor is compensated using the gas flow rate compensation value, specifically:

[0020] Calculate the volume fraction φ of water vapor in the actual measured flue gas;

[0021]

[0022] in, is the water vapor partial pressure, P is the collected pressure value;

[0023] Calculate the molar mass M of the mixed gas actually measured eff ;

[0024]

[0025] Among them, M dry is the average molar mass of dry flue gas, is the molar mass of water vapor;

[0026] Calculate the specific heat ratio γ of the gas in the actual measured flue gas wet ;

[0027]

[0028] Among them, Cp,dry and Cv,dry are the specific heat capacities of dry flue gas at constant pressure and constant volume, respectively; Cp,H2O and φCv,H2O are the specific heat capacities of water vapor at constant pressure and constant volume, respectively;

[0029] The gas flow rate compensation value c(T,P,H) of each ultrasonic sensor is:

[0030]

[0031] Where T is the measured temperature, α1 is the pressure correction coefficient, α2 is the humidity correction coefficient, P0 is the standard atmospheric pressure, and R is the gas constant;

[0032] The gas flow rate u of the ultrasonic sensor is compensated by the gas flow rate compensation value. i make compensation;

[0033]

[0034] in, is the gas flow rate after compensation of the i-th ultrasonic sensor.

[0035] Optionally, the transducer of the ultrasonic sensor transmits ultrasonic waves by first transmitting n pulse waves of a first frequency, and then transmitting n pulse waves of a second frequency after half a cycle of the first frequency; the amplitude difference between the first frequency receiving wave and the second frequency receiving wave of the transducer of the ultrasonic sensor is the attenuation degree, and whether the current signal attenuation of the ultrasonic sensor is normal attenuation is judged according to the attenuation degree. If not, an alarm is issued and the data is discarded.

[0036] Optionally, the gas flow rate after compensation of all ultrasonic sensors is fused to obtain the fused flue gas flow rate, specifically: the gas flow rate after compensation of all ultrasonic sensors is fused by Kalman filtering. Or fuse the compensated gas flow rate of all ultrasonic sensors according to the set weight of each ultrasonic sensor Get the flue gas flow rate after fusion.

[0037] In a second aspect, a flue gas emission flow measurement system based on an ultrasonic multi-sensor array is provided, comprising:

[0038] A plurality of mounting rods are inserted into the flue in a predetermined manner, each of the mounting rods being provided with a plurality of ultrasonic sensors spaced apart along its length and an auxiliary sensor group corresponding to each of the ultrasonic sensors, the auxiliary sensor group including a temperature sensor, a pressure sensor, and a humidity sensor;

[0039] The data acquisition module is used to collect data from the ultrasonic sensor and the auxiliary sensor group, and to filter and pre-process the collected data;

[0040] The gas flow rate acquisition module is used to obtain the gas flow rate corresponding to each ultrasonic sensor based on the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the difference in propagation time between the upstream and downstream measured by the ultrasonic sensor;

[0041] a flow rate compensation module, configured to correct the gas flow rate of each ultrasonic sensor based on the temperature, humidity, and pressure values corresponding to the ultrasonic sensor, obtain a gas flow rate compensation value for each ultrasonic sensor, and compensate the gas flow rate of each ultrasonic sensor using the gas flow rate compensation value;

[0042] A flue flow acquisition module is used to fuse the compensated gas flow rates of all ultrasonic sensors to obtain the fused flue gas flow rate, and to obtain the flue gas emission flow rate based on the fused flue gas flow rate;

[0043] The display terminal is used to display the acquired flue gas emission flow in real time.

[0044] Optionally, when the flue is a rectangular flue, a grid is divided according to equal area, and a plurality of mounting rods are extended along the long side or the short side of the flue, so that the ultrasonic sensors and the auxiliary sensor groups are placed in the grid in a one-to-one correspondence;

[0045] When the flue is a circular flue, each mounting rod is distributed along the radius of the flue, and the intervals between adjacent mounting rods are the same. The number and spacing of ultrasonic sensors on each mounting rod are determined according to the number of concentric circles divided by the equal annular area method, and the number of mounting rods is determined according to the number of ultrasonic sensors set in each concentric circle.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention can address the uneven distribution of flow in the flue by setting multiple ultrasonic sensors in the flue, and then dynamically compensate for the gas flow rate detected by the ultrasonic sensors. In the dynamic compensation process, the correction of gas composition as well as temperature and pressure are taken into account; in addition, all compensated gas flow rates are integrated to obtain the gas flow rate closest to the actual situation of the flue, and the flue gas flow measurement is realized based on the gas flow rate closest to the actual situation of the flue. The method of the present invention can realize accurate measurement of flow in complex flue gas environments, so that the flow error is ≤±1.5% (traditional technology is more than ±5%). In addition, the application adopts multiple ultrasonic sensors, which have strong anti-interference performance compared to single-point measurement, thereby further ensuring accurate measurement of flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the steps of the flue gas emission flow measurement method based on ultrasonic multi-sensor array of the present invention;

[0049] Figure 2 is a schematic diagram of the arrangement of the ultrasonic sensor of the present invention;

[0050] Figure 3 Schematic diagram of the installation position of the ultrasonic sensor of the present invention;

[0051] Figure 4 This is a cross-sectional detection principle diagram of the ultrasonic sensor of the present invention;

[0052] Figure 5 Schematic diagram of the transmitting wave and receiving wave of the ultrasonic sensor of the present invention;

[0053] Figure 6 It is a structural schematic diagram of the smoke emission flow measurement system based on ultrasonic multi-sensor array of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be further described below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. It should be noted that the term "comprising" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0055] Example 1

[0056] like Figure 1 As shown, a method for measuring flue gas emission flow based on an ultrasonic multi-sensor array includes the following steps:

[0057] S1: several ultrasonic sensors and auxiliary sensor groups are set in the flue according to the set layout. The auxiliary sensor group includes a temperature sensor, a pressure sensor and a humidity sensor.

[0058] The ultrasonic sensor uses a small ultrasonic flow velocity detector with a size of ≤Φ80×80mm, an operating frequency of 80kHz~200kHz, and a transducer made of high-temperature piezoelectric ceramics (PZT-8). The transducer surface is treated with anti-corrosion treatment. All sensors are cooled by air-cooled sleeves or semiconductor refrigeration modules (controlling the probe temperature to <80℃) to ensure the adaptability of the ultrasonic sensor and auxiliary sensor group in high temperature and high humidity environments.

[0059] Temperature detector: PT100 platinum resistance (range -50°C to 600°C, accuracy ±0.5%). Pressure detector: Piezoresistive sensor (range 0 to 200 kPa, accuracy ±0.1% FS). Humidity sensor: Capacitive polymer film sensor (range 0 to 100% RH, accuracy ±2% RH).

[0060] The signals collected from each sensor must be conditioned and preprocessed. The preprocessing includes timestamp alignment, outlier processing, filtering, and normalization. For details, please refer to existing technologies. When collecting signals, a 24-bit high-precision ADC with a sampling rate of 1MS / s can be used to support the simultaneous acquisition of 16-channel ultrasonic signals. Signal conditioning can be achieved by integrating adaptive bandpass filtering (cutoff frequency adjustable range ±10% of center frequency) to amplify the programmable gain (gain 1 to 1000 times). In addition, the LMS algorithm is used to suppress power frequency interference, and the signal-to-noise ratio is improved by ≥20dB.

[0061] In this embodiment, the layout method of the ultrasonic sensor array is:

[0062] like Figure 2 As shown, Figure 2 (a) is a schematic diagram of the ultrasonic sensor arrangement structure of a circular flue. Figure 2 (b) is a schematic diagram of the ultrasonic sensor layout structure of the rectangular flue.

[0063] When the flue is circular, it is divided into several concentric circles according to the equal ring area method. Each concentric circle is divided into grids with equal areas according to the number of ultrasonic sensors, and ultrasonic sensors and auxiliary sensor groups are installed correspondingly in the grids.

[0064] When the flue is a rectangular flue, it is divided into grids of equal area, and ultrasonic sensors and auxiliary sensor groups are arranged in the grids. The ratio of the number of ultrasonic sensors on the long side to the short side of the rectangular flue is 2:1-3:1.

[0065] The distance between two adjacent ultrasonic sensors is greater than or equal to 20 mm.

[0066] The number of ultrasonic sensors can be obtained by modeling using tools such as COMSOL.

[0067] S2: Obtain the gas flow rate corresponding to each ultrasonic sensor based on the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the difference in the upstream and downstream propagation time measured by the ultrasonic sensor.

[0068] like Figure 4 As shown, the time difference between the propagation of ultrasonic waves in the downstream and countercurrent directions in the gas medium is proportional to the average flow velocity of the gas. The gas flow velocity can be calculated by calculating the relationship between the propagation time difference of ultrasonic waves and the propagation distance.

[0069] Specifically,

[0070] Among them, u i is the gas flow rate corresponding to the i-th ultrasonic sensor, L is the distance between the two transducers of the ultrasonic sensor, θ is the angle between the ultrasonic propagation direction of the ultrasonic sensor and the cross section of the flue, t1 and t2 are the acoustic time of the ultrasonic wave during forward and reverse propagation, respectively; τ1 and τ2 are the acoustic delay of the ultrasonic wave during forward and reverse propagation, respectively (the acoustic delay caused by circuits, cables, and transducers, etc.).

[0071] S3: Based on the temperature, humidity and pressure values collected by each ultrasonic sensor, the gas flow rate of the ultrasonic sensor is corrected, a gas flow rate compensation value of each ultrasonic sensor is obtained, and the gas flow rate of each ultrasonic sensor is compensated using the gas flow rate compensation value.

[0072] Step S3 specifically includes the following sub-steps:

[0073] S31: Calculate the volume fraction φ of water vapor in the actual measured flue gas;

[0074]

[0075] in, is the water vapor partial pressure (can be converted from relative humidity), P is the collected pressure value;

[0076] S32: Calculate the molar mass M of the mixed gas actually measured eff ;

[0077]

[0078] Among them, M dry is the average molar mass of dry flue gas, is the molar mass of water vapor (M H2O=0.018 kg / mol).

[0079] S33: Calculate the specific heat ratio γ of the gas in the actual measured flue gas wet ;

[0080]

[0081] Among them, Cp,dry and Cv,dry are the specific heat capacities of dry flue gas at constant pressure and constant volume, respectively; Cp,H2O and φCv,H2O are the specific heat capacities of water vapor at constant pressure and constant volume, respectively;

[0082] S34: The gas flow rate compensation value c(T, P, H) of each ultrasonic sensor is:

[0083]

[0084] Where T is the measured temperature, α1 is the pressure correction factor, α2 is the humidity correction factor, P0 is the standard atmospheric pressure (101325 Pa), and R is the gas constant 8.314 J / (mol·K);

[0085] Different working conditions (e.g., 150°C / 500 Pa / 30% RH) were simulated in a temperature and humidity test chamber, and a laser Doppler velocimeter (LDV) was used as a reference to calibrate α1 and α2.

[0086] S35: Using the gas flow rate compensation value to calculate the gas flow rate u of the ultrasonic sensor i make compensation;

[0087]

[0088] in, is the gas flow rate after compensation of the i-th ultrasonic sensor.

[0089] It is worth noting that the compensation of gas flow rate can be real-time, but in some other embodiments, sliding window filtering is used: the moving average of the gas flow rate compensation values c(T, P, H) of 10 consecutive cycles is calculated, and then compensation is performed.

[0090] S4: fusing the compensated gas flow rates of all ultrasonic sensors to obtain a fused flue gas flow rate, and obtaining a flue gas emission flow rate based on the fused flue gas flow rate.

[0091] The fusion method includes: using Kalman filtering to fuse the compensated gas flow rate of all ultrasonic sensors Obtain the flue gas flow rate after fusion. For details, you can refer to the existing technology. As an optional method, define the state variable as the actual flue gas flow rate (i.e., the flue gas flow rate after fusion), build a dynamic model (flow rate changing model over time) and an observation model (the relationship between the gas flow rate of each ultrasonic sensor and the actual flow rate), build a noise covariance matrix, and initialize it. Then, predict and update the actual flow rate, and determine the weight of the predicted value and the measured value by calculating the Kalman gain. Finally, fuse multiple compensated gas flow rates. The state estimation and error covariance are updated, and after iterative optimization, the optimal actual gas flow rate is obtained, which is the fused flue gas flow rate.

[0092] In some other embodiments, the compensated gas flow rates of all ultrasonic sensors are fused according to the set weights of each ultrasonic sensor. Get the flue gas flow rate after fusion.

[0093] Specifically, in this embodiment, since the grids are divided into equal areas, that is, the weight of each ultrasonic sensor is set to be consistent, that is, the gas flow rate after compensation of all ultrasonic sensors is calculated. The average of the flue gas flow rate after fusion can be obtained.

[0094] The flue gas emission flow rate is obtained based on the flue gas flow rate after the flue fusion. Specifically, the gas flow rate can be obtained by multiplying the flue gas flow rate after the fusion by the flue cross-sectional area.

[0095] In this embodiment, the ultrasonic sensor transducer transmits ultrasonic waves by first transmitting n (5) pulse waves of a first frequency (100KHz), and then transmitting n (5) pulse waves of a second frequency (200KHz) after half a cycle of the first frequency. The amplitude difference between the first frequency receiving wave and the second frequency receiving wave of the ultrasonic sensor transducer is the attenuation degree. According to the attenuation degree, it is judged whether the current signal attenuation of the ultrasonic sensor is normal attenuation. If not, an alarm is issued and the data is discarded. Specifically, the waveform of the attenuation degree is analyzed as follows: Figure 5 shown.

[0096] The dual-frequency transmission method can effectively enhance waveform feature acquisition through phase notching, thereby improving anti-interference capabilities. At the same time, it can also judge humidity through the amplitude difference between 100KHz and 200KHz, as well as the correlation between gain value and humidity, thereby enhancing waveform signal processing capabilities. Humidity correlation and signal gain, sound speed, and signal characteristics can be used to determine whether the signal attenuation is normal due to transducer humidity, transducer dirt, or transducer attenuation itself.

[0097] Example 2

[0098] like Figure 6 As shown, a flue gas emission flow measurement system based on an ultrasonic multi-sensor array is provided, comprising:

[0099] Several mounting rods are inserted into the flue in a set manner. On each mounting rod, several ultrasonic sensors are spaced apart along the length thereof, and an auxiliary sensor group corresponding to the ultrasonic sensors is provided. The auxiliary sensor group includes a temperature sensor, a pressure sensor and a humidity sensor.

[0100] The mounting rod has a diameter of ≤45mm and is adjustable in length (300 to 1500mm). It is made of 316L stainless steel or titanium alloy. The detection box has a built-in signal processing circuit, an IP66 protection rating, and a temperature resistance of -20°C to +80°C. The connection between the mounting rod and the ultrasonic sensor can be based on existing techniques. The auxiliary sensor group can be mounted on the mounting rod through connecting rods or directly on the mounting rod.

[0101] When the flue is rectangular, it is divided into grids of equal area, and several mounting rods are extended along the long side or short side of the flue so that the ultrasonic sensors and the auxiliary sensor groups are placed in the grid in a one-to-one correspondence;

[0102] When the flue is circular, each mounting rod is distributed along the radius of the flue, and the intervals between adjacent mounting rods are the same. The number and spacing of ultrasonic sensors on each mounting rod are determined by the number of concentric circles divided by the equal annular area method. The number of mounting rods is determined by the number of ultrasonic sensors set in each concentric circle, such as Figure 3 As shown, Figure 3 (a) is a schematic diagram of the installation position of the ultrasonic sensor and the mounting rod. Figure 3 (b) is a schematic diagram of the installation position of the ultrasonic sensor and the mounting rod from a top view.

[0103] The mounting rod is usually inserted into the flue through a Φ110mm flange, and the flange is sealed with a polytetrafluoroethylene gasket.

[0104] The data acquisition module is used to collect data from the ultrasonic sensor and the auxiliary sensor group, and to filter and pre-process the collected data;

[0105] The gas flow rate acquisition module is used to obtain the gas flow rate corresponding to each ultrasonic sensor based on the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the difference in propagation time between the upstream and downstream measured by the ultrasonic sensor;

[0106] a flow rate compensation module, configured to correct the gas flow rate of each ultrasonic sensor based on the temperature, humidity, and pressure values corresponding to the ultrasonic sensor, obtain a gas flow rate compensation value for each ultrasonic sensor, and compensate the gas flow rate of each ultrasonic sensor using the gas flow rate compensation value;

[0107] The flue flow acquisition module is used to fuse the compensated gas flow rates of all ultrasonic sensors to obtain the fused flue gas flow rate, and obtain the flue gas emission flow rate based on the fused flue gas flow rate.

[0108] The display terminal is used to display the acquired flue gas emission flow in real time. Of course, it can also be used to display the monitoring parameters of each sensor and the integrated flue gas flow rate, etc. The specific selection is based on actual needs.

[0109] For more specific details of the above method, please refer to the corresponding contents disclosed in the aforementioned embodiments, which will not be repeated here.

[0110] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. References to the same or similar parts between the various embodiments will be sufficient. The systems disclosed in the embodiments are described briefly because they correspond to the methods disclosed in the embodiments. For relevant details, refer to the method description.

[0111] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus a necessary general-purpose hardware platform. Based on this understanding, the technical solutions in the embodiments of the present invention, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments of the present invention or certain portions of the embodiments.

[0112] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for measuring flue gas emission flow based on an ultrasonic multi-sensor array, characterized in that: include: Several ultrasonic sensors and auxiliary sensor groups are arranged in the flue according to a set layout, wherein the auxiliary sensor group includes a temperature sensor, a pressure sensor and a humidity sensor; The gas flow rate corresponding to each ultrasonic sensor is obtained based on the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the difference in propagation time between the upstream and downstream measured by the ultrasonic sensor. Based on the temperature, humidity, and pressure values corresponding to each ultrasonic sensor, the gas flow rate of the ultrasonic sensor is corrected to obtain a gas flow rate compensation value for each ultrasonic sensor, and the gas flow rate of each ultrasonic sensor is compensated using the gas flow rate compensation value; The compensated gas flow rates of all ultrasonic sensors are fused to obtain a fused flue gas flow rate, and the flue gas emission flow rate is obtained based on the fused flue gas flow rate.

2. The method for measuring flue gas emission flow based on ultrasonic multi-sensor array according to claim 1, characterized in that: The method of setting up a plurality of ultrasonic sensors and auxiliary sensor groups in the flue in accordance with a predetermined layout is as follows: If the flue is circular, it is divided into several concentric circles according to the equal ring area method. Each concentric circle is divided into grids with equal areas according to the number of ultrasonic sensors, and ultrasonic sensors and auxiliary sensor groups are installed in the grids accordingly. When the flue is rectangular, it is divided into grids of equal area, and ultrasonic sensors and auxiliary sensor groups are arranged in the grids, with the ratio of the number of ultrasonic sensors on the long side to the short side of the rectangular flue being 2:1-3:1; The distance between two adjacent ultrasonic sensors is greater than or equal to 20 mm.

3. The method for measuring flue gas emission flow based on ultrasonic multi-sensor array according to claim 1, characterized in that: The gas flow rate corresponding to each ultrasonic sensor is obtained based on the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the difference in propagation time between the upstream and downstream measured by the ultrasonic sensor; specifically: Among them, u i is the gas flow rate corresponding to the i-th ultrasonic sensor, L is the distance between the two transducers of the ultrasonic sensor, θ is the angle between the ultrasonic propagation direction of the ultrasonic sensor and the cross section of the flue, t1 and t2 are the acoustic times of the ultrasonic wave during forward and reverse propagation, respectively; τ1 and τ2 are the acoustic delays of the ultrasonic wave during forward and reverse propagation, respectively.

4. The method for measuring flue gas emission flow based on ultrasonic multi-sensor array according to claim 1, characterized in that: The gas flow rate of each ultrasonic sensor is corrected based on the temperature, humidity, and pressure values corresponding to each ultrasonic sensor, a gas flow rate compensation value of each ultrasonic sensor is obtained, and the gas flow rate of each ultrasonic sensor is compensated using the gas flow rate compensation value, specifically: Calculate the volume fraction φ of water vapor in the actual measured flue gas; in, is the water vapor partial pressure, P is the collected pressure value; Calculate the molar mass M of the mixed gas actually measured eff ; Among them, M dry is the average molar mass of dry flue gas, is the molar mass of water vapor; Calculate the specific heat ratio γ of the gas in the actual measured flue gas wet ; Among them, Cp,dry and Cv,dry are the specific heat capacities of dry flue gas at constant pressure and constant volume, respectively; Cp,H2O and φCv,H2O are the specific heat capacities of water vapor at constant pressure and constant volume, respectively; The gas flow rate compensation value c(T,P,H) of each ultrasonic sensor is: Where T is the measured temperature, α1 is the pressure correction coefficient, α2 is the humidity correction coefficient, P0 is the standard atmospheric pressure, and R is the gas constant; The gas flow rate u of the ultrasonic sensor is compensated by the gas flow rate compensation value. i make compensation; in, is the gas flow rate after compensation of the i-th ultrasonic sensor.

5. The method for measuring flue gas emission flow based on ultrasonic multi-sensor array according to claim 1, characterized in that: The transducer of the ultrasonic sensor transmits ultrasonic waves by first emitting n pulse waves of a first frequency, and then emitting n pulse waves of a second frequency after half a cycle of the first frequency. The amplitude difference between the first-frequency receiving wave and the second-frequency receiving wave of the ultrasonic sensor transducer is the attenuation degree. The attenuation degree is used to determine whether the current signal attenuation of the ultrasonic sensor is normal. If not, an alarm is issued and the data is discarded.

6. The method for measuring flue gas emission flow based on ultrasonic multi-sensor array according to claim 1, characterized in that: The gas flow rate after compensation of all ultrasonic sensors is fused to obtain the fused flue gas flow rate, specifically: the gas flow rate after compensation of all ultrasonic sensors is fused by Kalman filtering. Or fuse the compensated gas flow rate of all ultrasonic sensors according to the set weight of each ultrasonic sensor Get the flue gas flow rate after fusion.

7. A flue gas emission flow measurement system based on an ultrasonic multi-sensor array, characterized in that: include: A plurality of mounting rods are inserted into the flue in a predetermined manner, each of the mounting rods being provided with a plurality of ultrasonic sensors spaced apart along its length and an auxiliary sensor group corresponding to each of the ultrasonic sensors, the auxiliary sensor group including a temperature sensor, a pressure sensor, and a humidity sensor; The data acquisition module is used to collect data from the ultrasonic sensor and the auxiliary sensor group, and to filter and pre-process the collected data; The gas flow rate acquisition module is used to obtain the gas flow rate corresponding to each ultrasonic sensor based on the distance between the two transducers of the ultrasonic sensor, the angle between the ultrasonic propagation direction and the flue cross section, and the difference in propagation time between the upstream and downstream measured by the ultrasonic sensor; a flow rate compensation module, configured to correct the gas flow rate of each ultrasonic sensor based on the temperature, humidity, and pressure values corresponding to the ultrasonic sensor, obtain a gas flow rate compensation value for each ultrasonic sensor, and compensate the gas flow rate of each ultrasonic sensor using the gas flow rate compensation value; A flue flow acquisition module is used to fuse the compensated gas flow rates of all ultrasonic sensors to obtain the fused flue gas flow rate, and to obtain the flue gas emission flow rate based on the fused flue gas flow rate; The display terminal is used to display the acquired flue gas emission flow in real time.

8. The flue gas emission flow measurement system based on ultrasonic multi-sensor array according to claim 7, characterized in that: When the flue is rectangular, it is divided into grids of equal area, and several mounting rods are extended along the long side or short side of the flue so that the ultrasonic sensors and the auxiliary sensor groups are placed in the grid in a one-to-one correspondence; When the flue is a circular flue, each mounting rod is distributed along the radius of the flue, and the intervals between adjacent mounting rods are the same. The number and spacing of ultrasonic sensors on each mounting rod are determined according to the number of concentric circles divided by the equal annular area method, and the number of mounting rods is determined according to the number of ultrasonic sensors set in each concentric circle.

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