CN117782238A - Large-pipe-diameter non-steady flow section flow measurement method, equipment and nuclear facility ventilation system - Google Patents
Large-pipe-diameter non-steady flow section flow measurement method, equipment and nuclear facility ventilation system Download PDFInfo
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Abstract
The invention discloses a flow measuring method for a large-pipe-diameter non-steady flow section, which comprises the steps of firstly obtaining a Kelvin temperature value of air in a pipe section to be measured, then obtaining full pressure values at a plurality of positions and static pressure values at a plurality of positions in a set section of the pipe section to be measured, and obtaining the flow in the pipe of the pipe section to be measured through calculation according to the values. The method is limited by the length of the front and rear straight pipe sections of the measured section, greatly reduces the turbulence influence, and is suitable for measuring large-pipe-diameter flow. The invention also provides a large-pipe-diameter non-steady flow section flow measuring device and a nuclear facility ventilation system.
Description
Technical Field
The invention particularly relates to a large-pipe-diameter non-steady flow section flow measurement method, equipment and a nuclear facility ventilation system.
Background
The flow is one of key parameters of a pipeline system in a plurality of industrial fields, so that the flow measuring device has important significance in engineering application, provides key data support for the aspects of process control, energy management, fault diagnosis, safety, environmental protection and the like, and helps enterprises to realize efficiency improvement, cost control and sustainable development. The conventional flow measurer has a vortex shedding flowmeter by sensing karman vortex shedding frequency, an electromagnetic flowmeter using electromagnetic induction effect, an ultrasonic flowmeter applying a propagation velocity difference of ultrasonic waves in a fluid to measure a flow rate, a turbine flowmeter measuring a vortex moment generated when a liquid or gas flows through a turbine, an orifice plate/nozzle flowmeter calculating a flow rate by measuring a pressure difference upstream and downstream of a pipe, and the like.
Generally, in order to avoid unstable flow, turbulence effect and non-uniformity of flow velocity distribution, the position of the flow measurement device has certain requirements, and a certain length of straight pipe section needs to be reserved before and after the flow measurement device. According to different flow measurement standards and device requirements, it is generally recommended to install the flow measurement device on a straight pipe section, and the length of the straight pipe section is not less than 5 times of the pipe diameter from an upstream local resistance component (such as an elbow, a tee, etc.), and not less than 2 times of the pipe diameter from a downstream local resistance component.
However, if the main exhaust pipe in the factory building of the nuclear facility generally has a very large pipe diameter (the pipe diameter is greater than 1000 mm), if enough steady flow straight pipe sections are reserved at the upstream and downstream of the flow measuring device, the problems of difficult arrangement of the pipe, large occupied space, construction complexity, increased cost and the like are caused, and the layout of other important equipment is likely to be influenced, so that the necessary steady flow straight pipe sections are difficult to ensure under most conditions, if the arrangement is not required, the flow in the pipe is in a non-steady flow state, any point in the section is difficult to represent the flow value of the whole pipe, and therefore, the proper flow measuring device setting position is not available, and the stability and accuracy of flow measurement are also affected.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art and provides a large-pipe-diameter non-steady flow section flow measurement method which is limited by the length of the front and rear straight pipe sections of the measured section, greatly reduces the turbulence influence and is suitable for large-pipe-diameter flow measurement. The invention also provides a large-pipe-diameter non-steady flow section flow measuring device and a nuclear facility ventilation system.
The invention provides a flow measuring method for a large-pipe-diameter non-steady flow section, which comprises the following steps:
acquiring a Kelvin temperature value T of air in a pipe section to be detected;
acquiring a full pressure value p at m positions in a set section of a pipe section to be measured ti And static pressure value p at n positions si ，
And calculating to obtain the flow Q in the pipe of the pipe section to be measured through the following formula:
wherein p is a At atmospheric pressure, R a The gas constant of air, and xi is the flow velocity correction coefficient and is a set value; a is the sectional area of the pipe section to be measured.
Further, after the kelvin temperature value T of the air in the pipe section to be measured is obtained, the method further comprises the following steps: and taking the value of the correction coefficient xi according to the actually acquired temperature value T and the corresponding relation between the correction coefficient xi and the temperature value T.
The invention also provides a large-pipe-diameter non-steady flow section flow measuring device, which comprises a measuring unit and a control unit, wherein the measuring unit is arranged at a set section of the pipe section to be measured and is used for acquiring the Kelvin temperature value T of air in the pipe section to be measured and the full pressure value p at m positions in the set section ti And static pressure value p at n positions si The control unit is electrically connected with the measuring unit and is used for calculating the flow Q in the pipe of the pipe section to be measured according to the following formula:
wherein p is a At atmospheric pressure, R a The gas constant of air, and xi is the flow velocity correction coefficient of the measuring unit and is a set value; a is the sectional area of the pipe section to be measured.
Further, the corresponding relation between the correction coefficient ζ and the temperature value T is preset in the control unit, and the control unit is further configured to take the value of the correction coefficient ζ according to the temperature value T of the measurement unit and the corresponding relation, and calculate to obtain the pipe flow Q of the pipe segment to be measured according to the corrected coefficient ζ after taking the value.
Further, the measuring unit comprises a pressure measuring device, the pressure measuring device is arranged at the set section of the pipe section to be measured, and a plurality of pressure taking points which are uniformly distributed along the set section are arranged on the pressure measuring device, so that the full pressure value p is obtained through each pressure taking point ti And the static pressure value p si 。
Further, the pressure measuring device comprises a shell and pressure taking pipes, the pipe section to be measured is divided into two sections at the set section, the diameter sizes of the shell and the pipe section to be measured are consistent, the pressure taking pipes are connected between the two sections of the pipe section to be measured, the pressure taking pipes are provided with a plurality of pressure taking holes which are uniformly distributed along the set section and are connected to the shell, and each pressure taking point is a pressure taking hole formed in the pressure taking pipe.
Further, the pipe section to be measured is a rectangular pipe, a plurality of full-pressure taking pipes are arranged in the pressure taking pipes, the plurality of full-pressure taking pipes are distributed in a cross grid shape along the transverse and longitudinal directions of the set section, the full-pressure taking pipes transversely distributed along the set section are uniformly provided with a plurality of full-pressure taking holes, and the full-pressure taking holes are formed in one side, facing the upstream, of the full-pressure taking pipe.
Further, the pipe section that awaits measuring is circular pipe, the total pressure of getting in the pressure pipe is got and is pressed the pipe and be equipped with many, and one of them is the annular pipe that the laminating shell inner wall was arranged, and the radial of shell is followed to the other total pressure of many total pressure pipe of getting is pressed the pipe, and end connection annular pipe, each total pressure are got and are pressed and evenly offered a plurality of total pressures and get and press the hole, the total pressure is got and is pressed the pipe and be offered one side towards the upper reaches at the total pressure.
Further, the static pressure taking pipes in the pressure taking pipes are provided with a plurality of static pressure taking pipes, the arrangement structure of the plurality of static pressure taking pipes is consistent with that of the full pressure taking pipes, the static pressure taking pipes are arranged on one side of the full pressure taking pipes facing the downstream direction of gas flow, a plurality of static pressure taking holes are uniformly formed in each static pressure taking pipe, and the static pressure taking holes are formed in one side of the static pressure taking pipes facing the downstream direction.
Further, the static pressure taking pipe in the pressure taking pipe comprises a ring pipe and a branch pipe, the ring pipe is arranged on the outer side of the shell in a surrounding mode, the branch pipe is provided with a plurality of static pressure taking holes, the static pressure taking holes are uniformly arranged on the outer side of the shell in a surrounding mode along the axis of the shell and are perpendicular to the side wall of the shell, one end of the branch pipe is communicated with the ring pipe, the other end of the branch pipe is communicated with the side wall of the shell, and the static pressure taking holes are formed in the communicating position of the branch pipe and the shell.
Further, the measuring unit further comprises a temperature measuring device which is arranged on one side of the pressure measuring device facing the upstream direction of the gas flow and is used for acquiring the Kelvin temperature value of the air in the pipe section to be measured.
Further, in the pipe section to be measured, a straight pipe section with the length of at least 1D is arranged at the position where the set section is located in the direction towards the upstream of the gas flow, and a straight pipe section with the length of at least 0.5D is arranged in the direction towards the downstream of the gas flow, wherein D is the pipe diameter of the pipe section to be measured.
The invention also provides a nuclear facility ventilation system which comprises a ventilation pipeline and the large-pipe-diameter non-steady flow section flow measuring equipment, wherein the large-pipe-diameter non-steady flow section flow measuring equipment is arranged on a pipe section to be measured in the ventilation pipeline and is used for measuring the flow in the pipe section to be measured.
According to the large-pipe-diameter non-steady flow section flow measurement method, the temperature value in the pipe, the static pressure value and the full pressure value at a plurality of point positions are obtained, and then the flow in the pipe is obtained through calculation according to the obtained values. Compared with the current common flow measurement mode in the market, the numerical value according to the measurement method is the comprehensive numerical value of a plurality of positions in the section of the pipe section to be measured, rather than the numerical value of one measurement point is used for representing the numerical value of the whole pipeline, so that the control of the flow condition in the pipe is more comprehensive, and the flow result is more accurate and reliable.
Compared with the steady flow section, the pipeline of the unsteady flow section has more complicated pipeline internal conditions, completely different flow conditions exist at different positions of the same section in the pipeline, and turbulence influence exists.
And because of this, the measuring method can be used in large-diameter pipelines such as nuclear facility ventilation systems, and when the large-diameter pipelines cannot provide a measuring steady flow section due to layout modes, space limitations and the like, the measuring method can still obtain accurate and reliable flow values in the non-steady flow section.
Drawings
FIG. 1 (a) is a schematic diagram of the structure of a pressure measuring device in a large-diameter non-steady flow section flow measuring apparatus according to embodiment 2 of the present invention;
FIG. 1 (b) is a schematic vertical cross-sectional structure of FIG. 1 (a);
FIG. 1 (c) is a schematic view of the horizontal cross-sectional structure of FIG. 1 (a);
FIG. 2 (a) is a schematic structural diagram of a pressure measuring device in a large-diameter non-steady flow section flow measuring apparatus according to embodiment 3 of the present invention;
FIG. 2 (b) is a schematic vertical cross-sectional structure of FIG. 2 (a);
FIG. 2 (c) is a schematic view of the horizontal cross-sectional structure of FIG. 2 (a);
FIG. 3 (a) is a schematic diagram showing the structure of a pressure measuring device in the large-diameter non-steady flow section flow measuring apparatus according to example 4 of the present invention;
FIG. 3 (b) is a schematic vertical cross-sectional structure of FIG. 3 (a);
FIG. 3 (c) is a schematic view of the horizontal cross-sectional structure of FIG. 3 (a);
FIG. 4 (a) is a schematic structural diagram of a pressure measuring device in the large-diameter non-steady flow section flow measuring apparatus according to example 5 of the present invention;
FIG. 4 (b) is a schematic vertical cross-sectional structure of FIG. 4 (a);
FIG. 4 (c) is a schematic view of the horizontal cross-sectional structure of FIG. 4 (a);
FIG. 5 (a) is a schematic view of the structure of the large diameter non-steady flow section flow measurement device of embodiment 2 of the present invention disposed downstream of the elbow;
fig. 5 (b) is a schematic structural view of the flow measuring device of the large-diameter non-steady flow section in embodiment 2 of the present invention, which is disposed downstream of the tee.
In the figure: 1. a measuring unit; 11. a pressure measuring device; 111. a housing; 112. a full-pressure taking pipe; 1121. a full-pressure taking hole; 113. a static pressure taking pipe; 1131. a grommet; 1132. a branch pipe; 1133. a static pressure taking hole; 114. externally connecting a full-pressure taking pipe; 115. externally connecting a static pressure taking pipe; 12. a temperature measuring device; 2. a pipe section to be measured; 3. differential pressure transmitter.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent, and the embodiments described in detail, but not necessarily all, in connection with the accompanying drawings. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
In the description of the present invention, it should be noted that, the terms "upper," "lower," and the like indicate an orientation or a positional relationship based on the orientation or the positional relationship shown in the drawings, and are merely for convenience and simplicity of description, and do not indicate or imply that the apparatus or element in question must be provided with a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "connected," "configured," "mounted," "secured," and the like are to be construed broadly and may be either fixedly connected or detachably connected, or integrally connected, for example; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those skilled in the art according to the specific circumstances.
Example 1
The flow measuring method of the large-pipe-diameter non-steady flow section of the embodiment adopts the embodiments 2 to 2
The measuring device in embodiment 5, the method specifically includes the steps of:
acquiring a Kelvin temperature value T of air in a pipe section 2 to be measured;
acquiring full pressure value p at m positions in set section of pipe section 2 to be measured ti And static pressure value p at n positions si ，
The in-pipe flow rate Q of the pipe section 2 to be measured is calculated by the following formula:
wherein p is a Atmospheric pressure (Pa), R a Is the gas constant of air (J.kg) -1 ·K -1 ) (287.0 in this embodiment), ζ is a flow velocity correction coefficient of the measurement unit 1, which is a set value; a is the cross-sectional area (m) of the pipe section 2 to be measured 2 )
Specifically, full pressure value p is obtained from m positions ti I.e. the obtained full-pressure values are p t1 、p t2 、p t3 … … to p tm Obtaining static pressure value p from n positions si I.e. the static pressure values obtained are p s1 、p s2 、p s3 … … to p sn Full pressure p in the obtained set section t Static pressure p s The method comprises the following steps of:
the average dynamic pressure p in the section is set d The method comprises the following steps:
and then defining according to the dynamic pressure:
wherein v is a theoretical average flow velocity (m/s) of a set section, ρ is an air density (kg/m) 3 )。
Assuming that the air in the pipe section 2 to be measured is an ideal gas which is not compressible, there are:
p s -p a ＝ρR a T (5)
is obtained by conversion of the formula (4) and the formula (5):
considering the influence factors of the air flowing around the measuring unit 1, the fluid viscosity at different temperatures, the different sizes and shapes of the measuring unit 1, and the like, the correction coefficient ζ should be considered on the basis of the theoretical average flow velocity v to obtain the actual average flow velocity u (m/s) of the set cross section, then there are:
therefore, the in-pipe flow rate Q can be obtained from formula (7) as:
in this embodiment, after obtaining the kelvin temperature value T of the air in the pipe section 2 to be measured, the method further includes the following steps: and taking the value of the correction coefficient xi according to the actually acquired temperature value T and the corresponding relation between the correction coefficient xi and the temperature value T.
In this embodiment, after the preparation of the measuring device is completed, each measuring device is also tested before leaving the factory, and the testing mode includes that the measuring device 1 is correspondingly installed on a model of the pipe section 2 to be tested, and simulated ventilation is performed on the pipe section 2 to be tested under a plurality of different temperature environments, and the simulated ventilation flow is a known value, so that the corresponding relation between the correction coefficient ζ and the temperature value T can be obtained.
Compared with the current common flow measurement mode in the market, the numerical value according to the measurement method is the comprehensive numerical value of a plurality of positions in the section of the pipe section to be measured, rather than the numerical value of one measurement point is used for representing the numerical value of the whole pipeline, so that the control of the flow condition in the pipe is more comprehensive, and the flow result is more accurate and reliable.
Compared with the steady flow section, the pipeline of the unsteady flow section has more complicated pipeline internal conditions, completely different flow conditions exist at different positions of the same section in the pipeline, and turbulence influence exists.
And because of this, the measuring method can be used in large-diameter pipelines such as nuclear facility ventilation systems, and when the large-diameter pipelines cannot provide a measuring steady flow section due to layout modes, space limitations and the like, the measuring method can still obtain accurate and reliable flow values in the non-steady flow section.
Example 2
The large-diameter non-steady flow section flow measuring device of the embodiment comprises a measuring unit 1 and a control unit, wherein the measuring unit 1 is arranged at a set section of a pipe section 2 to be measured, and is used for obtaining a Kelvin temperature value T (with the unit of K) of air in the pipe section 2 to be measured and a full pressure value p at m positions in the set section as shown in fig. 1 and 5 ti And static pressure value p at n positions si The control unit is electrically connected with the measuring unit 1 and is used for calculating and obtaining the pipe flow rate Q of the pipe section 2 to be measured through the following formula:
wherein p is a Atmospheric pressure (Pa), R a Is the gas constant of air (J.kg) -1 ·K -1 ) ζ is a flow velocity correction coefficient of the measurement unit 1, which is a set value; a is the cross-sectional area (m) of the pipe section 2 to be measured 2 )。
The measuring device of the embodiment firstly obtains the temperature value in the pipe, the static pressure value and the full pressure value at a plurality of points through the measuring unit 1, and then calculates the flow in the pipe through the control unit according to the obtained values. Compared with the current common flow measuring device on the market, the numerical value according to the measuring equipment is the comprehensive numerical value of a plurality of positions in the section of the pipe section 2 to be measured, rather than the numerical value of one measuring point is used for representing the numerical value of the whole pipeline, so that the control of the flow condition in the pipe is more comprehensive, and the flow result is more accurate and reliable.
For the pipeline of the non-steady flow section, the condition of the pipeline is more complex than that of the steady flow section, completely different flowing conditions exist at different positions of the same section in the pipeline, and turbulent flow influence exists.
And because of this point too, this measuring equipment can be used to in big pipe diameter pipelines such as nuclear facility ventilation system, when this kind of big pipe diameter pipeline is because of layout mode and space restriction etc. can't accomplish to provide and measure stationary flow section, this measuring equipment still can acquire accurate reliable flow value in the unsteady flow section.
The measuring device adopts the measuring concept of differential pressure measurement and data transformation, improves the flow measurement accuracy of a flow measurement scheme at the position with larger pipe diameter and shorter straight pipe sections before and after positioning, shortens the length of the straight pipe sections required before and after positioning, and improves the application range of the device.
In this embodiment, after the preparation of the measuring devices is completed, each measuring device is tested before leaving the factory, and the testing mode includes that the measuring device is correspondingly installed on a model of the pipe section 2 to be tested, and simulated ventilation is performed on the pipe section 2 to be tested under a plurality of different temperature environments, and the corresponding relation between the correction coefficient ζ and the temperature value T can be obtained because the simulated ventilation flow is a known value.
The corresponding relation between the correction coefficient xi and the temperature value T is preset in the control unit, the control unit is further used for taking the value of the correction coefficient xi according to the temperature value T and the corresponding relation of the measurement unit 1, and calculating the flow Q in the pipe of the pipe section 2 to be measured according to the corrected coefficient xi after taking the value, so that the influence of the structure of the measurement unit 1 on the detection result is eliminated, the influence of the temperature on the change of the fluid viscosity is eliminated, and the accuracy of the measurement result is further improved.
In this embodiment, the measuring unit 1 includes a pressure measuring device 11, where the pressure measuring device 11 is installed at a set section of the pipe section 2 to be measured, and a plurality of pressure taking points uniformly distributed along the set section are provided on the pressure measuring device 11, so as to obtain the full pressure value p through each pressure taking point ti And static pressure value p si 。
In this embodiment, the pressure measuring device 11 includes a casing 111 and a pressure-taking tube, where the section 2 to be measured is divided into two sections at a set section, the diameter sizes of the casing 111 and the section 2 to be measured are identical, and the pressure-taking tube is connected between the two sections of the section 2 to be measured, and is provided with a plurality of pressure-taking tubes, which are uniformly distributed along the set section and are connected to the casing 111, and each pressure-taking point is a pressure-taking hole formed on the pressure-taking tube. In this embodiment, each pressure-taking tube is made of stainless steel, and the material of the casing 111 is preferably stainless steel or carbon steel according to the use conditions such as the moisture content of air in the tube, the concentration of radioactive substances, the acidity and alkalinity, and the polluting gas. The joints between the shell 111 and the pressure taking pipes are all full-welded.
Specifically, the pressure-taking tube includes a full-pressure-taking tube 112, a static pressure-taking tube 113, an external full-pressure-taking tube 114 and an external static pressure-taking tube 115. A section of the full-pressure-taking pipe 112 penetrates from one side of the casing 111 and is communicated with an external full-pressure-taking pipe 114, and a section of the static pressure-taking pipe 113 extends out and is communicated with an external static pressure-taking pipe 115. The control unit can be provided with a PLC and a differential pressure transmitter 3, an external full-pressure taking pipe 114 and an external static pressure taking pipe 115 are communicated into the differential pressure transmitter 3, the differential pressure transmitter 3 performs data acquisition, and then the PLC performs calculation and data conversion to obtain the flow in the pipeline.
In this embodiment, the air pressure sensing components may be disposed at each pressure-taking position, so as to obtain static pressure and full pressure, and the static pressure and full pressure may be transmitted to the differential pressure transmitter 3, or the pressure-taking pipes may be communicated, that is, the pressure-taking pipes 112 are all of mutually communicated structures, the pressure-taking pipes 113 are of mutually communicated structures, and the pressure at each pressure-taking position is directly and automatically averaged in the pipe and then communicated to the differential pressure transmitter 3 by the external pipe to obtain average pressure.
The casing 111 selects a suitable cross-sectional structure according to the cross-sectional structure of the pipe section 2 to be measured, in this embodiment, the pipe section 2 to be measured is rectangular in cross section, so the casing 111 is a rectangular structure adapted to the structure of the pipe section 2 to be measured.
Therefore, the flow rate Q in the rectangular-section tube can be further obtained from the formula (8) in example 1 as follows:
wherein a is the length (m) of the section of the rectangular pipe section 2 to be measured; b is the width (m) of the section of the rectangular pipe section 2 to be measured.
In this embodiment, the pipe section 2 to be measured is a rectangular pipe, as shown in fig. 1 (a) to 1 (c), the plurality of full-pressure taking pipes 112 are arranged in the pressure taking pipes, and the plurality of full-pressure taking pipes 112 are distributed in a cross grid along the transverse and longitudinal directions of the set section, wherein a plurality of full-pressure taking holes 1121 are uniformly formed in each full-pressure taking pipe 112 distributed along the transverse direction of the set section, and the full-pressure taking holes 1121 are formed on the upstream side of the full-pressure taking pipe 112. The full pressure gauge tubes 112 are welded to form a grid-like structure.
In this embodiment, the static pressure taking pipe 113 in the pressure taking pipe includes a collar 1131 and a branch pipe 1132, the collar 1131 is disposed around the outer side of the housing 111 in a rectangular annular layout manner, the branch pipe 1132 is provided with a plurality of branches, the branches evenly encircle the outer side of the housing 111 along the axis of the housing 111 and are all perpendicular to the side wall of the housing 111, one end of the branch pipe 1132 is communicated with the collar 1131, the other end of the branch pipe 1132 is communicated with the side wall of the housing 111, and a static pressure taking hole 1133 is formed at the communicating position with the housing 111, and the static pressure taking hole 1133 is a structure penetrating through the wall surface of the housing 111.
In this embodiment, the measuring unit 1 further includes a temperature measuring device 12, where the temperature measuring device 12 may be a temperature sensor, and the temperature measuring device 12 is disposed on a side of the pressure measuring device 11 facing the upstream direction of the gas flow, for obtaining the kelvin temperature value of the air in the pipe section 2 to be measured, and the set position may directly sense the gas temperature, so as to avoid being affected by the pressure measuring device 11. The temperature measuring device 12 is integrated with the pressure measuring device 11, and can be used as multi-parameter measuring equipment for measuring various physical quantities such as temperature, static pressure, dynamic pressure, full pressure, flow rate, volume flow and mass flow in a pipeline by carrying out data transmission, conversion and display with a control unit.
In this embodiment, as shown in fig. 5 (a) and 5 (b), in the pipe section 2 to be measured, the set section is perpendicular to the incoming flow direction of the gas flow, a straight pipe section with a length of at least 1D (or 1-1.5D) is disposed at a position where the set section is located toward the upstream direction of the gas flow, and a straight pipe section with a length of at least 0.5D (or 0.5-1D) is disposed toward the downstream direction of the gas flow, where D is the pipe diameter of the pipe section 2 to be measured. That is, when the measuring device is installed at the downstream of the elbow pipe or the three-way pipe, the upstream of the measuring device is reserved with a straight pipe section with the pipe diameter of at least 1 time, and when the measuring device is installed at the upstream of the elbow pipe or the three-way pipe, the downstream of the measuring device is reserved with a straight pipe section with the pipe diameter of at least 0.5 time, therefore, the requirement on the length of the straight pipe section of the measuring device is extremely low, and the limitation on the measuring condition is greatly reduced.
Since the pipe section 2 to be measured in the embodiment is a rectangular pipe, the pipe diameter D herein is the equivalent diameter of the pipe section, i.e., d=2ab/(a+b), and a is the length (m) of the cross section of the rectangular pipe section 2 to be measured; b is the width (m) of the section of the rectangular pipe section 2 to be measured.
The flow measurement device of the embodiment adopts the measurement concepts of full pressure-static pressure measurement and data transformation to measure the difference between the full pressure and the static pressure, combines the pipeline parameters and the fluid property to perform data transformation, can provide higher measurement precision, and particularly can realize accurate flow measurement by correctly selecting the pressure taking position and a proper data processing method in a pipeline with a larger pipe diameter and shorter front and rear pressure stabilizing and flow stabilizing sections. Compared with other flow measurement schemes, such as an electromagnetic flowmeter, an ultrasonic flowmeter and the like, the flow measurement scheme provided by the embodiment does not need to change a pipeline structure on a large scale, reduces the cost of installation and maintenance, has more economic benefits when applied to a large-diameter pipeline, avoids the problem that a traditional flowmeter needs to keep a longer steady flow section before and after a measurement position and needs a larger test space, and enables the device to be used for flow measurement of a non-steady flow section at a position close to a bent pipe or a tee.
Example 3
The present embodiment is substantially the same as embodiment 2, except that, as shown in fig. 2 (a) to 2 (c), in the present embodiment, the pipe section 2 to be measured is circular in cross section, so the housing 111 is a circular structure adapted to the structure of the pipe section 2 to be measured.
Therefore, from the formula (8) in example 1, the circular cross-section in-pipe flow rate Q can be further obtained as:
wherein D is the pipe diameter (m) of the circular pipe section 2 to be measured.
In this embodiment, the pipe section 2 to be tested is a circular pipe, the total pressure taking pipe 112 in the pressure taking pipe is provided with a plurality of ring pipes, one of the ring pipes is attached to the inner wall of the casing 111, the rest of the total pressure taking pipes 112 are radially distributed along the radial direction of the casing 111, the end is connected with the annular pipe, all pipes are welded and connected, a plurality of full-pressure taking holes 1121 are uniformly formed in all the full-pressure taking pipes 112, and the full-pressure taking holes 1121 are formed in one side, facing the upstream, of the full-pressure taking pipes 112.
The static pressure taking pipe 113 is similar to that in embodiment 1, and includes a collar 1131 and a branch pipe 1132, where the collar 1131 is disposed around the outer side of the casing 111 in a circular layout manner, the branch pipes 1132 are disposed around the outer side of the casing 111 uniformly along the axis of the casing 111, and are perpendicular to the side wall of the casing 111, that is, disposed radially along the casing 111, one end of the branch pipe 1132 is communicated with the collar 1131, the other end is communicated with the side wall of the casing 111, and a static pressure taking hole 1133 is formed at a communicating position with the casing 111, and the static pressure taking hole 1133 is a structure penetrating through the wall surface of the casing 111.
Example 4
The present embodiment is basically the same as embodiment 2, except that in the present embodiment, as shown in fig. 3 (a) to 3 (c), the layout of the static pressure taking pipe 113 in the taking pipe is different.
In this embodiment, the static pressure taking-out pipes 113 are provided with a plurality of static pressure taking-out pipes 113, and the arrangement structure of the plurality of static pressure taking-out pipes 113 is consistent with that of the full pressure taking-out pipes 112, and is also a grid-like layout structure which is intersected horizontally and longitudinally, and is arranged at one side of the full pressure taking-out pipes 112 facing the downstream direction of the gas flow, that is, the mesh grid formed by arranging the full pressure taking-out pipes 112 is in fit connection with the mesh grid formed by arranging the static pressure taking-out pipes 113, and the mesh grid is respectively facing the upstream and the downstream. Each static pressure taking pipe 113 is uniformly provided with a plurality of static pressure taking holes 1133, and the static pressure taking holes 1133 are formed on one side of the static pressure taking pipe 113 facing downstream.
Example 5
The present embodiment is basically the same as embodiment 3, except that in the present embodiment, as shown in fig. 4 (a) to 4 (c), the layout of the static pressure taking pipe 113 in the taking pipe is different.
In this embodiment, the static pressure taking and pressing pipes 113 are provided with a plurality of static pressure taking and pressing pipes 113, and the arrangement structure of the plurality of static pressure taking and pressing pipes 113 is consistent with that of the full pressure taking and pressing pipes 112, that is, one static pressure taking and pressing pipe 113 is an annular pipe which is arranged to be attached to the inner wall of the casing 111, the rest of the plurality of static pressure taking and pressing pipes 113 are radially distributed along the radial direction of the casing 111, the end of each static pressure taking and pressing pipe 113 is connected with the annular pipe in a welding way. The static pressure taking pipe 113 is arranged at one side of the full pressure taking pipe 112 facing the downstream direction of the gas flow, namely, the radial grid formed by arranging the full pressure taking pipe 112 and the radial grid formed by arranging the static pressure taking pipe 113 are in fit connection, and the radial grid are respectively facing the upstream and the downstream. Each static pressure taking pipe 113 is uniformly provided with a plurality of static pressure taking holes 1133, and the static pressure taking holes 1133 are formed on one side of the static pressure taking pipe 113 facing downstream.
Example 6
The nuclear facility ventilation system of this embodiment includes ventilation pipe and big pipe diameter unsteady flow section flow measuring equipment in embodiment 2 through embodiment 5, and big pipe diameter unsteady flow section flow measuring equipment installs on the pipeline section 2 that awaits measuring in the ventilation pipe for the intraductal flow of survey pipeline section 2.
The ventilation system in the embodiment can remove the waste heat and the waste moisture in the room in the nuclear facility factory building, and control pollutants in a reasonable range, and the air supply and exhaust amounts required by different functional rooms are different. The ventilation system can be further provided with a monitoring system, and the large-pipe-diameter non-steady flow section flow measuring equipment can be arranged on a branch pipe and a main pipe of the air supply and exhaust system of the nuclear facility factory building and combined with the monitoring system, can be used for monitoring and adjusting the whole air supply and exhaust quantity of each room and the system, and can be used for monitoring the working state of the ventilation system (such as detecting fan faults, pipeline blockage or leakage, sending out alarm signals when the air quantity is abnormal, and the like), so that the safe and stable operation of the production flow of the nuclear facility factory building is ensured.
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (13)
1. The flow measuring method for the large-pipe-diameter non-steady flow section is characterized by comprising the following steps of:
acquiring a Kelvin temperature value T of air in a pipe section (2) to be detected;
acquiring full pressure value p at m positions in a set section of a pipe section (2) to be measured ti And static pressure value p at n positions si ，
Calculating to obtain the flow Q in the pipe of the pipe section (2) to be measured through the following formula:
wherein p is a At atmospheric pressure, R a The gas constant of air, and xi is the flow velocity correction coefficient and is a set value; a is the sectional area of the pipe section (2) to be measured.
2. The method for measuring the flow rate of the large-diameter non-steady flow section according to claim 1, wherein after the kelvin temperature value T of the air in the pipe section (2) to be measured is obtained, the method further comprises the following steps:
and taking the value of the correction coefficient xi according to the actually acquired temperature value T and the corresponding relation between the correction coefficient xi and the temperature value T.
3. The utility model provides a big pipe diameter unsteady flow section flow measuring equipment which characterized in that: comprises a measuring unit (1) and a control unit,
the measuring unit (1) is arranged at a set section of the pipe section (2) to be measured and is used for acquiring the Kelvin temperature value T of air in the pipe section (2) to be measured and the full pressure value p at m positions in the set section ti And static pressure value p at n positions si ，
The control unit is electrically connected with the measuring unit (1) and is used for calculating the flow Q in the pipe of the pipe section (2) to be measured according to the following formula:
wherein p is a At atmospheric pressure, R a Is the gas constant of air, and xi is the flow velocity correction coefficient of the measuring unit (1) and is a set value; a is the sectional area of the pipe section (2) to be measured.
4. A large pipe diameter non-steady flow section flow measurement device according to claim 3, characterized in that: the corresponding relation between the correction coefficient xi and the temperature value T is preset in the control unit,
the control unit is also used for taking the value of the correction coefficient xi according to the temperature value T of the measuring unit (1) and the corresponding relation, and calculating to obtain the flow Q in the pipe of the pipe section (2) to be measured according to the corrected coefficient xi after taking the value.
5. A large pipe diameter non-steady flow section flow measurement device according to claim 3, characterized in that: the measuring unit (1) comprises a pressure measuring device (11),
the pressure measuring device (11) is arranged at the set section of the pipe section (2) to be measured, and a plurality of pressure taking points which are uniformly distributed along the set section are arranged on the pressure measuring device (11) so as to be used forThe full pressure value p is obtained through each pressure taking point ti And the static pressure value p si 。
6. The large pipe diameter non-steady flow section flow measurement device of claim 5, wherein: the pressure measuring device (11) comprises a shell (111) and a pressure taking pipe,
the pipe section (2) to be measured is divided into two sections at the set section, the diameter size of the shell (111) is consistent with that of the pipe section (2) to be measured, and the shell is connected between the two sections of the pipe section (2) to be measured,
the pressure taking pipes are provided with a plurality of pressure taking holes which are uniformly distributed along a set section and connected to the shell (111), and each pressure taking point is a pressure taking hole formed in the pressure taking pipe.
7. The large pipe diameter non-steady flow section flow measurement device of claim 6, wherein: the pipe section (2) to be measured is a rectangular pipe,
the total pressure taking pipes (112) in the pressure taking pipes are provided with a plurality of total pressure taking pipes (112) which are distributed in a cross grid shape along the transverse and longitudinal directions of the set section,
wherein a plurality of full-pressure taking holes (1121) are uniformly formed on each full-pressure taking pipe (112) which is transversely distributed along the set section,
the full-pressure taking hole (1121) is formed in the upstream side of the full-pressure taking pipe (112).
8. The large pipe diameter non-steady flow section flow measurement device of claim 6, wherein: the pipe section (2) to be measured is a round pipe,
the full-pressure taking pipes (112) in the pressure taking pipes are provided with a plurality of annular pipes, one of the annular pipes is arranged to be attached to the inner wall of the shell (111), the rest of the plurality of full-pressure taking pipes (112) are radially distributed along the radial direction of the shell (111), the tail ends of the all-pressure taking pipes are connected with the annular pipes,
a plurality of full-pressure taking holes (1121) are uniformly formed on each full-pressure taking pipe (112),
the full-pressure taking hole (1121) is formed in the upstream side of the full-pressure taking pipe (112).
9. The large pipe diameter non-steady flow section flow measurement device according to claim 7 or 8, characterized in that: the static pressure taking pipes (113) in the taking pipes are provided with a plurality of static pressure taking pipes (113), the arrangement structure of the static pressure taking pipes (113) is consistent with that of the full pressure taking pipes (112), the static pressure taking pipes are arranged at one side of the full pressure taking pipes (112) facing the downstream direction of the gas flow,
a plurality of static pressure taking holes (1133) are uniformly formed on each static pressure taking pipe (113),
the static pressure taking hole (1133) is formed in one side of the static pressure taking pipe (113) facing downstream.
10. The large pipe diameter non-steady flow section flow measurement device of claim 6, wherein: the static pressure taking pipe (113) in the taking pipe comprises a ring pipe (1131) and a branch pipe (1132),
the collar (1131) is arranged around the outer side of the shell (111),
the branch pipes (1132) are provided with a plurality of branch pipes which are uniformly and circumferentially arranged on the outer side of the shell (111) along the axis of the shell (111) and are perpendicular to the side wall of the shell (111),
one end of the branch pipe (1132) is communicated with the ring pipe (1131), the other end of the branch pipe is communicated with the side wall of the shell (111), and a static pressure taking hole (1133) is formed in a communicating position of the branch pipe and the shell (111).
11. The large pipe diameter non-steady flow section flow measurement device of claim 5, wherein: the measuring unit (1) also comprises a temperature measuring device (12),
the temperature measuring device (12) is arranged on one side of the pressure measuring device (11) facing the upstream direction of the gas flow and is used for acquiring the Kelvin temperature value of the air in the pipe section (2) to be measured.
12. A large pipe diameter non-steady flow section flow measurement device according to claim 3, characterized in that: in the pipe section (2) to be measured, a straight pipe section with the length of at least 1D is arranged at the position where the set section is located in the direction towards the upstream of the gas flow, and a straight pipe section with the length of at least 0.5D is arranged in the direction towards the downstream of the gas flow, wherein D is the pipe diameter of the pipe section (2) to be measured.
13. A nuclear facility ventilation system, characterized by: comprising a ventilation duct and a large-diameter non-steady flow section flow measuring device as claimed in any one of claims 3 to 12,
the large-pipe-diameter non-steady flow section flow measuring equipment is arranged on a pipe section (2) to be measured in the ventilating pipeline and is used for measuring the flow in the pipe of the pipe section (2) to be measured.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311744669.7A CN117782238A (en) | 2023-12-18 | 2023-12-18 | Large-pipe-diameter non-steady flow section flow measurement method, equipment and nuclear facility ventilation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311744669.7A CN117782238A (en) | 2023-12-18 | 2023-12-18 | Large-pipe-diameter non-steady flow section flow measurement method, equipment and nuclear facility ventilation system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117782238A true CN117782238A (en) | 2024-03-29 |
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ID=90384342
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311744669.7A Pending CN117782238A (en) | 2023-12-18 | 2023-12-18 | Large-pipe-diameter non-steady flow section flow measurement method, equipment and nuclear facility ventilation system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117782238A (en) |
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2023
- 2023-12-18 CN CN202311744669.7A patent/CN117782238A/en active Pending
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