A gas flow measurement system and method based on axial fan current collector structure

Abstract

The application discloses a kind of gas flow measurement systems and methods based on axial flow fan current collector structure, the axial flow fan includes the air inlet box, current collector, impeller section and diffuser connected in turn;The gas flow measurement system is connected by the pressure pipeline with the anti-blocking multi-point flute type pipe pressure taking device installed in the current collector and the local instrument cabinet;Local instrument cabinet is equipped with pressure transmitter, barometer, temperature controller, power switch, programmable logic controller, industrial control touch screen integrated machine and valve.The method comprises: using anti-blocking multi-point flute type pipe pressure taking device to measure the pressure of measuring section in real time;Through the integrated pressure acquisition module of local instrument cabinet, the dynamic pressure and static pressure of measuring section are collected and processed;The flow coefficient of the whole flow measurement device is obtained;Based on the calculation program built in programmable logic controller, the gas flow is calculated and uploaded in real time.The application can accurately and reliably measure the gas flow in large coal-fired boiler flue gas system in real time.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal-fired power plants, and particularly relates to a gas flow measurement system and method based on a structure of a collector of an axial flow fan. BACKGROUND

[0002] Gas flow is one of the key parameters for evaluating the operation state of a power station fan, and accurate and reliable measurement and real-time monitoring of the gas flow are important basis for evaluating and regulating the aerodynamic performance of the power station fan, and have important engineering application value for evaluating the health state of the power station fan. Since the flue gas ducts of large coal-fired units are large-diameter ducts (the equivalent diameter of the ducts is greater than 2 m), and are compactly arranged, have many special-shaped parts and few straight pipe sections, it is difficult to meet the measurement condition requirements of conventional gas flow measurement devices due to the turbulent flow field inside the ducts, and it is still a technical problem to be solved to accurately and reliably measure the gas flow in the flue gas ducts in real time.

[0003] At present, axial flow fans have been widely used in boiler flue gas systems, and in order to improve the operation efficiency of the axial flow fan, a collector structure is arranged in front of the impeller of the axial flow fan. The main function of the collector is to collect and accelerate the airflow, so that the airflow before entering the impeller is uniformly distributed, thereby ensuring the inlet conditions of the impeller. According to the statistical analysis of the application of domestic large thermal power units, the axial flow fan of the power station is configured with a collector structure having significant common characteristics. The structure is a typical tapered structure with a length of 0.5-2.5 m, and the flow field is uniform and stable in the outlet section of the collector, which provides favorable conditions for accurate measurement of the flue gas or air flow. SUMMARY

[0004] In order to accurately and reliably measure the gas flow in the flue gas system of a large coal-fired boiler in real time, the present application proposes a gas flow measurement system and method based on the structure of a collector of an axial flow fan.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A gas flow measurement system based on the structure of a collector of an axial flow fan, the axial flow fan comprising an inlet box, a collector, an impeller section and a diffuser connected in sequence; the gas flow measurement system is connected with a local instrument cabinet by a pressure pipeline, and the pressure pipeline takes pressure from a anti-blocking multi-point flute type pipe pressure taking device installed in the collector; the local instrument cabinet is provided with a pressure transmitter, an atmospheric pressure gauge, a temperature controller, a power switch, a programmable logic controller, an industrial control touch screen all-in-one machine and a valve, wherein the power switch controls the power supply of the entire local instrument cabinet, the valve realizes the connection and isolation of each pressure pipeline, the pressure transmitter, the atmospheric pressure gauge and the temperature controller respectively measure the medium pressure, the ambient atmospheric pressure and the medium temperature, and convert them into 4-20 mA signals which are collected to the programmable logic controller for data calculation and analysis, and finally transmitted to the industrial control touch screen all-in-one machine for storage and display.

[0007] The further improvement of the present application is that the impeller section is composed of an inlet guide vane, a moving vane and an outlet guide vane.

[0008] The further improvement of the present application is that the current collector is a conical cylinder taper structure, the taper angle of the current collector is β =40°~60°, the gas flow measurement section is 0.2m~1m away from the leading edge of the inlet guide vane, and the velocity section uniformity index at the section is l =0.92~1. gamma v =0.92~1.

[0009] The further improvement of the present application is that the anti-blocking multi-point flute type pipe pressure taking device is a composite flute type pipe structure, the number of static pressure measuring points of a single pressure taking pipe is n s =2~4, the number of total pressure measuring points is n d =2~6; and the number of pressure taking pipes along the axial direction is N =3~6.

[0010] The further improvement of the present application is that the pilot pressure pipeline is made of 316L stainless steel pipe.

[0011] The further improvement of the present application is that the data acquisition of the flow measurement device is realized through a programmable logic controller, the sampling period is t s =0.5s~1.0s, the number of samples per sampling period is m ≥10, and a continuous sampling multi-point average method is used for data processing, and the specific process is as follows:

[0012] The data set obtained by continuous sampling in a sampling period is P i , i =1,2,..., m The measurement value after data processing at this moment is

[0013] .

[0014] A gas flow measurement method based on a structure of a current collector of an axial flow fan, which is based on a gas flow measurement system based on a structure of a current collector of an axial flow fan, and comprises:

[0015] A anti-blocking multi-point flute type pipe pressure taking device is used to take pressure in real time at the measurement section;

[0016] The dynamic pressure and static pressure of the measurement section are collected and processed through an integrated pressure collection module of an on-site instrument cabinet, including data filtering and abnormal data elimination;

[0017] The correction coefficient of the anti-blocking multi-point whistle type pipe pressure taking device is obtained through a standard laboratory platform, and the velocity field coefficient of the flow measurement surface is obtained through high-precision numerical simulation calculation, and then the flow coefficient of the whole flow measurement device is obtained.

[0018] The gas flow is calculated based on the built-in calculation program of the local programmable logic controller and is uploaded in real time.

[0019] Further improvement of the present application is that the correction coefficient of the multi-point pressure taking pipe is obtained through a standard laboratory platform, and the velocity field coefficient of the flow measurement surface is obtained through high-precision numerical simulation calculation, and then the flow coefficient of the whole flow measurement device is obtained, which is as follows:

[0020] The composite whistle type pipe is calibrated in the standard closed pipeline flow measurement platform to obtain the velocity correction coefficient epsilon .

[0021] A full three-dimensional flow channel model is established according to the actual fan structure size, numerical calculation analysis is carried out, and the number of calculation conditions k ≥3, the fan inlet flow should cover the whole use range, at the same time, according to the distribution of the measurement section, the static pressure and total pressure values at the measurement section measurement point position under each calculation condition are extracted, that is, the calculation result data set{( Q v-cal , , , ) j}, j =1,2,..., k ;

[0022] Based on the numerical simulation result{( Q v-cal , , , ) j}, the velocity field coefficient under each condition is calculated through the relationship between flow and dynamic pressure of the measurement surface zeta j :

[0023]

[0024] Based on the calculation result data set{( , , ) j}, the relationship between the velocity field coefficient of the flow measurement section and the measurement value is obtained through linear regression fitting .

[0025] The flow coefficient of the whole flow measurement device .

[0026] The further improvement of the present application is that the value range of the speed correction coefficient epsilon is [0.8~1].

[0027] The further improvement of the present application is that the flow coefficient of the whole flow measuring device obtained according to the calibration and digital model technology and the actual volumetric flow of the medium calculated according to the measured parameters Q v :

[0028] .

[0029] Compared with the prior art, the present application has at least the following beneficial technical effects:

[0030] The present application provides a flow measuring system and method of axial flow fan collector structure, which installs anti-blocking multi-point whistle type pressure taking device on the axial flow fan collector, measures total pressure and static pressure of flue gas in real time, calibrates the pressure taking pipe based on the standard air volume test bench to obtain correction coefficient, analyzes the internal flow field of the fan by numerical simulation calculation to obtain the velocity field coefficient of the measuring section, and then obtains the accurate flow coefficient of the flow measuring device, and finally, the flow of flue gas is obtained in real time based on the relationship between dynamic pressure and volumetric flow.

[0031] The present application relies on the typical structure and internal flow field distribution characteristics of the axial flow fan collector, effectively solves the problems of low flow measurement precision in large cross-section pipeline and easy blocking of flow measuring device under complex working conditions, and provides a solution for realizing high-precision online measurement of flue gas flow.

[0032] The present application has the characteristics of high efficiency, high precision and strong reliability, and is suitable for monitoring the gas flow parameters of the flue gas and air system of large coal-fired boilers. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a structural schematic diagram of the system of the present application;

[0034] Figure 2 is a principle diagram of the method of the present application;

[0035] Among them, Figure 2 Among them, P t is the total pressure of the medium measured by the flow measuring device, unit Pa, P s is the static pressure of the medium measured by the flow measuring device, unit Pa, T is the temperature of the medium in the measuring section, unit ℃, P atm is the local atmospheric pressure, unit Pa, The total pressure of the medium after averaging multiple samples continuously collected by the built-in program, in Pa. This is the static pressure of the medium after averaging multiple samples continuously collected by the built-in program, in Pa. The measured surface medium temperature is the average of multiple samples continuously collected by the built-in program, expressed in °C. This is the local atmospheric pressure, measured in Pa, after averaging multiple samples continuously collected by a built-in program. m For consecutive sample numbers, Q v-cal This is the volumetric flow rate under a specific operating condition for numerical simulation analysis of an axial flow fan to which a flow measurement device is to be installed. The unit is m³ / h. k To calculate the number of operating conditions, j To calculate the working condition number ( j =1,2,…, k ), epsilon The speed correction coefficient of the pressure tapping device obtained under a standard test platform. zeta j Let λ be the velocity field coefficient of the measurement section obtained under the j-th calculation condition, and λ be the flow coefficient of the entire flow measurement device after calibration. Q v The volumetric flow rate is measured in real time, and the unit is m³ / h. rho j For the first j The density of the medium at the measurement section under each calculated operating condition, in kg / m³. rho 0 represents the density of the medium under standard conditions, in kg / m³. A The area of ​​the measured surface is in meters (m²). 2 , where a and b are the coefficients of the relationship between the velocity field coefficient and the measured value.

[0036] In the attached diagram: 1. Inlet box; 2. Collector; 3. Impeller section; 4. Diffuser; 5. Anti-clogging multi-point flute-shaped pressure tapping device; 6. Pressure tapping pipeline; 7. Local instrument cabinet; 8. Pressure transmitter; 9. Atmospheric pressure gauge; 10. Temperature controller; 11. Power switch; 12. Programmable logic controller; 13. Industrial control touch screen all-in-one machine; 14. Valve. Detailed Implementation

[0037] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0038] 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.

[0039] 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 "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0040] In the present application, unless otherwise explicitly specified 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.

[0041] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include the direct contact of the first and second features, or can include the contact of the first and second features through another feature between them. Moreover, the "upper", "above" and "above" of the first feature to the second feature includes the first feature 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 "below", "below" and "below" of the first feature to the second feature includes the first feature 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0047] Example 1

[0048] like Figure 1 As shown in the figure, this embodiment provides a gas flow measurement system based on an axial flow fan collector structure. The axial flow fan includes an inlet box 1, a collector 2, an impeller section 3, and a diffuser 4 connected in sequence. The gas flow measurement system connects the anti-clogging multi-point flute-shaped pressure tapping device 5 installed in the collector 2 to a local instrument cabinet 7 via a pressure tapping pipeline 6. The local instrument cabinet 7 is equipped with a pressure transmitter 8, an atmospheric pressure gauge 9, a temperature controller 10, a power switch 11, a programmable logic controller 12, an industrial control touch screen all-in-one machine 13, and a valve 14. The power switch 11 controls the power supply of the entire local instrument cabinet, and the valve 14 realizes the access and isolation of each pressure tapping pipeline. The pressure transmitter 8, atmospheric pressure gauge 9, and temperature controller 10 measure the medium pressure, ambient atmospheric pressure, and medium temperature respectively, and convert them into 4~20mA signals, which are then aggregated to the programmable logic controller 12 for data calculation and analysis, and finally transmitted to the industrial control touch screen all-in-one machine for storage and display.

[0049] In this embodiment, the impeller section 3 consists of inlet guide vanes, moving vanes, and outlet guide vanes. The collector 2 has a tapered conical structure with a tapering angle of [missing information]. β =40°~60°, distance from the gas flow measurement section to the leading edge of the inlet guide vane l =0.2m~1m, and the velocity cross-sectional uniformity index at the cross-section gammav =0.92~1.

[0050] In this embodiment, the anti-blocking multi-point whistle type pipe pressure taking device 5 is a composite whistle type pipe structure, the number of static pressure measuring points of a single pressure taking pipe n s =2~4, the number of total pressure measuring points n d =2~6; and the number of pressure taking pipes uniformly distributed along the axial direction N =3~6.

[0051] In this embodiment, the pilot line 6 is made of 316L stainless steel pipe.

[0052] In this embodiment, the data acquisition of the flow measurement device is realized by a programmable logic controller, the sampling period t s =0.5s~1.0s, the number of samples per sampling period m ≥10, and a continuous sampling multi-point average method is used for data processing, which is specifically as follows:

[0053] The data set obtained by continuous sampling in a sampling period is P i}, i =1,2,..., m The measurement value after data processing at this moment is:

[0054] .

[0055] Embodiment 2

[0056] As shown in Figure 1 and Figure 2 , the gas flow measurement method based on the axial flow fan current collector structure provided in this embodiment comprises:

[0057] Real-time pressure taking of the measurement section is realized by using an anti-blocking multi-point whistle type pipe pressure taking device;

[0058] Dynamic pressure and static pressure of the measurement section are collected and processed by an integrated pressure collection module of the on-site instrument cabinet, including data filtering and abnormal data rejection;

[0059] The correction coefficient of the anti-blocking multi-point whistle type pipe pressure taking device is obtained through a standard test room platform, and a high-precision numerical simulation calculation is carried out to obtain the velocity field coefficient of the flow measurement surface, and then the flow coefficient of the whole flow measurement device is obtained;

[0060] The gas flow is calculated by a built-in calculation program of the on-site programmable logic controller and is uploaded in real time.

[0061] In this embodiment, the multi-point pressure tap calibration coefficient is performed using a standard laboratory platform, and the velocity field coefficient of the flow measurement surface is obtained through high-precision numerical simulation calculations. This leads to the flow coefficient of the entire flow measurement device, as detailed below:

[0062] 1) The composite flute tube is calibrated using a fluid flow measurement platform in a standard closed pipeline to obtain the velocity correction coefficient. epsilon Speed ​​correction coefficient epsilon The value range is [0.8~1];

[0063] 2) Establish a full three-dimensional flow channel model based on the actual wind turbine structural dimensions, conduct numerical calculations and analysis, and calculate operating condition numbers. k ≥3, the inlet flow rate of the fan should cover the entire operating range. Simultaneously, based on the layout of the measurement cross-sections, extract the static pressure and total pressure values ​​at the measurement points under each calculation condition, thus obtaining the calculation result dataset {( Q v-cal , , , ) j}, j =1,2,..., k ;

[0064] 3) Based on numerical simulation results {( Q v-cal , , , ) j The velocity field coefficients under various working conditions are calculated using the relationship between flow rate and dynamic pressure at the measuring surface. zeta j :

[0065]

[0066] 4) Based on the calculation result dataset {( , , ) j Linear regression fitting was performed to obtain the relationship between the velocity field coefficient of the flow measurement section and the measured value. ;

[0067] 5) Flow coefficient of the entire flow measurement device .

[0068] In this embodiment, the flow coefficient of the entire flow measurement device is obtained based on calibration and digital modeling techniques. The actual volumetric flow rate of the medium is calculated from the measured parameters. Q v :

[0069] .

[0070] Example 3

[0071] For a 600MW unit in China with adjustable blade axial flow induced draft fan, a full three-dimensional flow passage calculation model is established. Within the conventional working flow range of 200m³ / s~500m³ / s of the fan, four calculation conditions are selected for numerical simulation calculation to determine the measurement section that meets the speed uniformity requirement and obtain the speed field coefficient of the measurement section of the fan. Three anti-blocking multi-point flute type pressure tapping devices are evenly installed along the circumferential direction of the selected measurement section (the pressure tapping devices are calibrated through a standard air volume test bench), and a local instrument cabinet is configured. The pressure tapping device and the local instrument cabinet are connected through a 316L stainless steel pressure lead pipe, the processing of measurement data, flow calculation and compressed air blowing control to prevent pipeline and pressure tapping device blockage are realized through the programmable logic controller in the local instrument cabinet, and then the measured flow value is transmitted to the power plant fan online monitoring system platform through optical fiber to realize real-time monitoring of flow and monitoring and early warning of fan operating state. According to more than one year of field statistical data and field acceptance test data, the measurement error of the flow measurement system and method is within 3%, which has high precision and high reliability. The implementation of the present application provides a reliable solution for high-precision real-time measurement of the flow of the flue gas and air system.

[0072] Example 4

[0073] On a 1000MW thermal power unit in China with adjustable blade axial flow induced draft fan, the gas flow measurement system and method of the present application are used to monitor the flue gas flow through the fan body in real time. According to DL / T 469-2022 "Field Performance Test of Power Plant Boiler Fan", the online monitoring flow is compared, and the measurement accuracy of the online monitoring flow is verified based on the comparison test values. The comparison test is carried out at unit loads of 1000MW, 750MW and 500MW, respectively. The comparison of the measured flow and the flow monitoring value at each working condition is shown in the following table.

[0074] Table 1 Comparison test results

[0075]

[0076] The foregoing merely illustrates the principles of the application and application of its leading features. This application is not limited to the exact details shown above and described herein, and obvious modifications will occur to those skilled in the art upon reading the foregoing description. Therefore, the scope of the application is not to be determined by the specific examples shown above, but only by the claims below. Any reference signs in the claims should not be construed as limiting the scope of the claims.

[0077] Furthermore, it should be understood that although the description above relates to embodiments, not every embodiment contains only one independent technical solution, and the description above is only for the sake of clarity, and those skilled in the art should understand the description as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand. The above is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made on the basis of the technical idea of the present application to the technical solutions falls within the protection scope of the claims of the present application.

Claims

1. A gas flow measurement system based on a structure of axial flow fan current collector, characterized in that, The axial flow fan comprises an air inlet box (1), a flow collector (2), an impeller section (3) and a diffuser (4) connected in sequence; the gas flow measurement system is connected by the pressure lead line (6) between the anti-blocking multi-point whistle type pressure tapping device (5) installed in the flow collector (2) and the on-site instrument cabinet (7); the on-site instrument cabinet (7) is provided with a pressure transmitter (8), an atmospheric pressure gauge (9), a temperature controller (10), a power switch (11), a programmable logic controller (12), an industrial control touch screen all-in-one machine (13) and a valve (14), wherein the power switch (11) controls the power supply of the whole on-site instrument cabinet, the valve (14) realizes the access and isolation of each pressure lead line, the pressure transmitter (8), the atmospheric pressure gauge (9) and the temperature controller (10) respectively measure the medium pressure, the ambient atmospheric pressure and the medium temperature and convert them into 4-20 mA signals to be collected to the programmable logic controller (12) for data calculation and analysis and finally transmitted to the industrial control touch screen all-in-one machine for storage and display; The measurement method of the measurement system comprises: The anti-blocking multi-point whistle type pressure tapping device is used to take pressure at the measurement section in real time; The dynamic pressure and static pressure of the measurement section are collected and processed by the integrated pressure collection module of the on-site instrument cabinet, including data filtering and abnormal data rejection; The correction coefficient of the anti-blocking multi-point whistle type pressure tapping device is obtained through a standard laboratory platform, and the velocity field coefficient of the flow measurement surface is obtained through high-precision numerical simulation calculation, and then the flow coefficient of the whole flow measurement device is obtained; The gas flow is calculated by the built-in calculation program of the on-site programmable logic controller and uploaded in real time; The correction coefficient of the multi-point pressure tapping pipe is obtained through a standard laboratory platform, and the velocity field coefficient of the flow measurement surface is obtained through high-precision numerical simulation calculation, and then the flow coefficient of the whole flow measurement device is obtained, as follows: The composite flute type pipe is calibrated in a standard closed pipeline to obtain a velocity correction coefficient ε ; According to the actual fan structure size, a full three-dimensional flow passage model is established, numerical calculation analysis is carried out, and the working condition number k ≥3, the fan inlet flow should cover the entire use range, at the same time, according to the measurement section distribution, the static pressure and total pressure values at the measurement section measurement point positions under each calculation working condition are extracted, that is, the calculation result data set is obtained Q v-cal , , , ) j}, j =1,2,..., k ; Based on numerical simulation results {( Q v-cal , , , ) j The velocity field coefficients under various working conditions are calculated using the relationship between flow rate and dynamic pressure at the measuring surface. ζ j : Based on the computed result data set , , ) j Linear regression fit to the velocity field coefficients of the flow measurement section Relationship to the measured values ; Flow coefficient of entire flow measuring device ; In the formula, P t The total pressure of the medium measured by the flow measurement device, in Pa. P s The static pressure of the medium measured by the flow measurement device, in Pa. k To calculate the number of operating conditions, j To calculate the operating condition number, j =1,2,…, k , ε The speed correction coefficient of the pressure tapping device obtained under a standard test platform. ζ j The velocity field coefficients of the measured cross section obtained under the j-th calculation condition are... A The area of ​​the measured surface is in meters (m²). 2 a and b are the coefficients in the relationship between the velocity field coefficient and the measured value. ρ j For the first j The density of the medium at the measurement section under each calculated operating condition, in kg / m³. 3 , Q v-cal This refers to the volumetric flow rate under a specific operating condition for a numerical simulation analysis of an axial flow fan to which a flow measurement device is to be installed. The unit is m³. 3 / h.

2. A gas flow measurement system based on a structure of axial flow fan current collector according to claim 1, characterized in that, The impeller section (3) is composed of inlet guide vanes, moving vanes and outlet guide vanes.

3. A gas flow measurement system based on a structure of axial flow fan current collector according to claim 2, characterized in that, The collector (2) has a tapered conical structure with a tapered angle. β =40°~60°, distance from the gas flow measurement section to the leading edge of the inlet guide vane l =0.2m~1m, and the velocity cross-sectional uniformity index at the cross-section γ v =0.92~1.

4. The gas flow measurement system based on the structure of axial flow fan flow collector according to claim 1, characterized in that, The anti-blocking multi-point whistle type pipe pressure tapping device (5) is a composite whistle type pipe structure, and the number of static pressure measuring points of a single pressure tapping pipe n s =2~4, and the number of total pressure measuring points n d =2~6; and the number of axial distribution pressure tapping pipes N =3~6.

5. The gas flow measurement system based on the structure of axial flow fan flow collector according to claim 1, characterized in that, The pressure lead line (6) is made of 316L stainless steel pipe.

6. A gas flow measurement system based on a structure of axial flow fan current collector according to claim 1, characterized in that, The data acquisition of the flow measuring device is realized by the programmable logic controller, the sampling period t s = 0.5s~1.0s, the sampling number of each sampling period m ≥10, and the data is processed by the continuous sampling multi-point average method, specifically as follows: The data set obtained by continuous sampling in a sampling period is P i}, i =1,2,..., m The measurement value after data processing in the sampling period is ​ In the formula, m is the number of consecutive samples.

7. The gas flow measurement system based on the structure of axial flow fan current collector according to claim 1, characterized in that, Speed correction coefficient ε is in the range [0.8, 1].

8. The gas flow measurement system based on the structure of axial flow fan current collector according to claim 1, characterized in that, The flow coefficient of the entire flow measuring device is obtained according to the calibration and the digital model technology The actual volume flow of the medium is calculated from the measured parameters Q v : In the formula, Ptot is the total pressure of the medium averaged over a plurality of samples taken successively by the built-in program, in Pa, Pstat is the static pressure of the medium averaged over a plurality of samples taken successively by the built-in program, in Pa, Tmeas is the temperature of the medium at the measurement surface averaged over a plurality of samples taken successively by the built-in program, in °C, Patm is the local atmospheric pressure averaged over a plurality of samples taken successively by the built-in program, in Pa, ρ 0 is the density of the medium at standard conditions, in kg / m 3 .

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