A stable flow, pressure-resistant and highly sensitive differential pressure flow meter

Abstract

The present invention provides a stable flow, pressure-resistant and highly sensitive differential pressure flowmeter, comprising: a base, a sensor assembly is arranged outside the base; a throttling assembly is arranged inside the base, the throttling assembly and the sensor assembly are connected through a measuring channel, and are used to introduce the fluid in the base into the measuring channel for flow measurement. The present invention is used to solve the problem that the existing flowmeter can only perform unidirectional measurement but not bidirectional measurement when the fluid direction and the high or low pressure in the flow channel change during operation; and the existing flowmeter cannot accurately measure the flow when there is fluid fluctuation (the direction of the fluid in the pipeline changes).

Description

Technical Field

[0001] The invention relates to the technical field of differential pressure flowmeters, and in particular to a stable-flow, pressure-resistant and highly sensitive differential pressure flowmeter. Background Art

[0002] The differential pressure flowmeter is an instrument for measuring flow rate. It uses the principle that there is a certain relationship between the pressure difference generated when the fluid flows through a throttling device and the flow rate, and realizes flow measurement by measuring the pressure difference.

[0003] The throttling structure is a key component of the differential pressure flowmeter. The blocking effect of the throttling component causes the fluid to generate a pressure difference at the front and rear ends of the throttling component. When in use, the traditional differential pressure flowmeter can only measure flow in one direction. When there is high or low pressure of gas in the pipeline or the direction of the fluid, such as jet or vortex, changes, the existing flowmeter cannot accurately measure the flow, thus affecting the accuracy of pipeline flow supervision data. Summary of the invention

[0004] The present invention provides a stable-flow, pressure-resistant and highly sensitive differential pressure flowmeter, which is used to solve the problem that the existing flowmeter can only perform unidirectional measurement but not bidirectional measurement when the fluid direction and the high or low pressure in the flow channel change during operation; and the problem that the existing flowmeter cannot accurately measure the flow when there is fluid fluctuation (the direction of the fluid in the pipeline changes).

[0005] The present invention provides a steady-flow, pressure-resistant and highly sensitive differential pressure flowmeter, comprising: a base, a sensor component is arranged outside the base; a throttling component is arranged inside the base, the throttling component and the sensor component are connected through a measuring channel, and are used to introduce the fluid in the base into the measuring channel for flow metering.

[0006] Preferably, the pressure balance assembly includes a pressure balance cover, which is arranged on the outside of the sensor assembly and is used to seal the sensor assembly and the flow measurement channel.

[0007] Preferably, the control panel is arranged above the sensor assembly, and the control panel is erected above the sensor assembly by means of a support, or is installed on the inner top surface of the outer cover by means of a support;

[0008] The control board is electrically connected to the sensor assembly and the external connector through a wire. The outer cover is arranged on the outside of the control board. The external connector is installed on one side of the outer cover and is used for electrically connecting to the external connector.

[0009] Preferably, the sensor assembly comprises:

[0010] A pressure sensor is located on the inner side wall of the pressure balance assembly and is provided with one or more pressure sensors, wherein the pressure sensors penetrate the pressure balance assembly through a wire and are connected to the control panel;

[0011] A temperature and humidity sensor is located on the inner wall of the pressure balance assembly and is provided with one or more temperature and humidity sensors, wherein the temperature and humidity sensors penetrate the pressure balance cover through a wire and are connected to the control board;

[0012] A differential pressure sensor is located on the inner wall of the pressure balance component and is provided with one or more differential pressure sensors, wherein the differential pressure sensors penetrate the pressure balance component through a wire and are connected to the control board; wherein the differential pressure sensor is located at the inlet and / or outlet of the measuring channel.

[0013] Preferably, the rectifying assembly is located in the fluid channel in the base, and includes one or more groups, and the rectifying assembly is used to rectify the fluid in the fluid channel.

[0014] Preferably, the rectifying component is formed by connecting a baffle, a fixing member, and a mesh plate in sequence; or, the rectifying member is formed by connecting a baffle, a fixing member, a mesh plate, a fixing member, and a mesh plate in sequence.

[0015] Preferably, the baffle is evenly distributed with a plurality of small holes, each of which is used to divert the inflowing / outflowing fluid and introduce it into a fixing member, and the fixing member then rectifies the fluid twice through a mesh plate and then flows it into a measuring channel for fluid flow measurement.

[0016] Preferably, the rectifying assembly is installed on the inlet / outlet port of the base through an end cover with a channel; the end of the end cover away from the base is connected to a pipe joint, and the pipe joint is used to connect a straight pipe.

[0017] The measuring channel is formed on the inner wall of the base by a component with a "┻"-shaped cross-section; the measuring channel is a "╝╚" structure, the upper part of the structure is used to connect the differential pressure sensor, and the lower two ends of the structure are respectively provided with ports P1 and port P2, wherein ports P1 and port P2 are located at the two ends of the throttling component, and are respectively used to introduce the fluid throttled by the throttling component into the measuring channel for measurement by the sensor component.

[0018] Preferably, when the flow direction state of the fluid Q in the fluid channel of the base through the throttling assembly is static, the pressure in the flow channel is port P1 = port P2;

[0019] When the flow direction of the fluid Q in the fluid channel of the base through the throttling assembly is from port P1 to port P2, the pressure in the flow channel is port P1>port P2;

[0020] When the flow direction of the fluid Q in the fluid channel of the base through the throttling assembly is from port P2 to port P1, the pressure in the measurement channel is port P1 < port P2.

[0021] Preferably, the measuring channel is provided with a pressure balance opening, and the pressure balance opening is used to introduce the fluid in the circulation channel into the pressure balance component;

[0022] When the pressure outside the differential pressure sensor is P0, the pressure differences between port P1, port P2 and the outside of the differential pressure sensor are (P1-P0)·S, (P2-P0)·S) respectively;

[0023] When the pressure outside the differential pressure sensor is P1, the pressure differences between port P1 and port P2 and the outside of the differential pressure sensor are 0 and (P2-P1)·S).

[0024] Wherein, S is the internal force-bearing area of ​​the differential pressure sensor structural housing.

[0025] Preferably, the throttling assembly comprises a low-pressure throttling assembly and a high-pressure throttling assembly, and the throttling passages of the low-pressure throttling assembly are fewer than the throttling passages of the high-pressure throttling assembly.

[0026] Preferably, the temperature and pressure of the fluid to be measured in the measuring channel are corrected:

[0027] Step 1: Use formula (1) to obtain the gas mass flow rate in the measurement channel:

[0028]

[0029] Wherein, C is the outflow coefficient; β is the ratio of the diameter of the opening area of ​​the throttling component (7) to the diameter of the pipe cross-sectional area; A0 is the opening area of ​​the throttling component; Δp is the static pressure difference (Pa) at the pressure taking point of the throttling component; ε is the expandability coefficient; p1 is the gas density before the throttling component; wherein p and Δp are both actual measurements; ε is a statistical quantity;

[0030] Step 2, obtain the gas density in the flow channel, use formula (2) and correct it for temperature and pressure:

[0031]

[0032] Among them, ρ n is the gas density under standard conditions; P n is the gas pressure under standard conditions; T n is the thermodynamic temperature of gas under standard conditions; P is the actual gas pressure; T is the actual thermodynamic temperature;

[0033] Step 3: Use formula (3) to calculate and obtain the corrected gas flow rate:

[0034]

[0035] Where Δp is the static pressure difference at the pressure point of the throttling component; P inis the air pressure inside the tube; P is the actual ambient atmospheric pressure; T is the actual gas thermodynamic temperature; k is the flow coefficient.

[0036] Preferably, the density of the mixed gas is calculated according to the content of each gas component; wherein the mixed gas is dry air with oxygen, carbon dioxide and water vapor added;

[0037]

[0038] Where Δp is the static pressure difference at the pressure point of the throttling component; P in is the air pressure in the tube; P is the actual ambient atmospheric pressure; T is the actual thermodynamic temperature; φ is the actual relative humidity; G is the actual carbon dioxide concentration; FIO2 is the actual oxygen concentration; F(T) is the percentage of air saturated with water vapor; k is the flow coefficient.

[0039] The working principle and beneficial effects of the present invention are as follows:

[0040] The present invention provides a steady-flow, pressure-resistant and highly sensitive differential pressure flowmeter, comprising: a base, a sensor component is arranged outside the base; a throttling component is arranged inside the base, the throttling component and the sensor component are connected through a measuring channel, and are used to introduce the fluid in the base into the measuring channel for flow metering.

[0041] Specifically, the throttling assembly is a key component of the differential pressure flowmeter. The blocking effect of the throttling component causes the fluid to generate a pressure difference at the front and rear ends of the throttling component. The throttling components of traditional differential pressure flowmeters include orifice plates, venturi tubes, nozzles and other structures. After nearly a hundred years of research, a large amount of empirical data has been accumulated and standardization has been achieved, but they all have their own shortcomings, such as small range, complex processing, poor repeatability, or easy clogging. The throttling assembly in the present invention has the advantages of good repeatability, stable measurement, high accuracy, simple structure, high reliability, and no moving parts. The technical solution provided by the present invention can solve the problem that when the flowmeter is used for measurement in the pipeline, when the direction of the fluid changes, it can only measure in one direction and cannot achieve two-way measurement; and the current flowmeter cannot accurately measure the flow when there is fluid fluctuation (the direction of the fluid in the pipeline changes).

[0042] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0043] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0045] Figure 1 It is a structural schematic diagram of the present invention;

[0046] Figure 2 It is a gas flow schematic diagram of the present invention;

[0047] Figure 3 It is a gas flow schematic diagram of the present invention;

[0048] Figure 4 It is a gas flow schematic diagram of the present invention;

[0049] Figure 5 It is a schematic diagram of the structure of the present invention without a pressure balancing component;

[0050] Figure 6 It is a schematic diagram of the structure of the pressure balance assembly of the present invention;

[0051] Figure 7 This is a schematic structural diagram of the enlarged view of point A of the present invention;

[0052] Figure 8 It is a structural schematic diagram of a rectifier assembly of the present invention;

[0053] Fig. 9 It is a schematic diagram of the cross-sectional structure of the rectifier assembly of the present invention;

[0054] Fig.10 It is a schematic diagram of the structure of the throttling assembly of the present invention;

[0055] Fig.11 It is a schematic diagram of the structure of the throttling assembly of the present invention;

[0056] Fig.12 A schematic diagram of the structure of the differential pressure sensor of the present invention;

[0057] Fig.13 This is a schematic diagram of the disassembled structure of a flow meter sample of the present invention;

[0058] Fig.14 It is a schematic diagram of the structure of a flow meter sample of the present invention;

[0059] Fig.15 is the flow measurement deviation rate under the open pressure condition of the present invention;

[0060] Fig.16 It is the flow measurement deviation rate under the pressure condition of 100KPa of the present invention;

[0061] Fig.17It is the flow measurement deviation rate under the pressure condition of 200KPa of the present invention;

[0062] Fig.18 It is the flow measurement deviation rate under the pressure condition of 300KPa of the present invention;

[0063] Fig.19 It is the flow measurement deviation rate under the pressure condition of 400KPa of the present invention;

[0064] Fig. 20 It is the flow measurement deviation rate under the pressure condition of 500KPa of the present invention;

[0065] Fig.21 It is the flow measurement deviation rate under the pressure condition of 600KPa of the present invention;

[0066] Fig. 22 It is the flow measurement deviation rate under the pressure condition of 750KPa of the present invention;

[0067] Fig.23 It is a comparison diagram of the flow meter measurement deviation rate curve in the pressure range of 0-750KPa of the present invention;

[0068] Fig.24 A comparison diagram of the full-scale deviation rate curve measured by the flowmeter in the pressure range of 0-750KPa of the present invention;

[0069] Among them, 1-rectifier assembly, 2-base, 3-pressure sensor, 4-temperature and humidity sensor, 5-differential pressure sensor, 6-pressure balance cover, 7-throttling assembly, 8-control board, 9-outer cover, 10-external connector, 11-end cover, 12-piping joint, 13-pressure balance opening, 101-baffle, 102-fixing part, 103-mesh plate. DETAILED DESCRIPTION

[0070] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0071] according to Figure 1 As shown, an embodiment of the present invention provides a steady-flow, pressure-resistant, and highly sensitive differential pressure flowmeter, comprising: a base 2, a sensor component is arranged outside the base 2; a throttling component 7 is arranged inside the base 2, the throttling component 7 and the sensor component are connected through a measuring channel, and are used to introduce the fluid in the base 2 into the measuring channel for flow measurement.

[0072] The throttling assembly is a key component of the differential pressure flowmeter. The blocking effect of the throttling component causes the fluid to generate a pressure difference at the front and rear ends of the throttling component. The throttling components of traditional differential pressure flowmeters include orifice plates, venturi tubes, nozzles and other structures. After nearly a hundred years of research, a large amount of empirical data has been accumulated and standardization has been achieved, but they all have their own shortcomings, such as small range, complex processing, poor repeatability, or easy clogging. The throttling assembly in the present invention has the advantages of good repeatability, stable measurement, high accuracy, simple structure, high reliability, and no moving parts. The technical solution provided by the present invention can solve the problem that when the flow meter is used for measurement in the pipeline, when the direction of the fluid changes, it can only measure in one direction and cannot achieve two-way measurement; and the current flow meter cannot accurately measure the flow when there is fluid fluctuation (the direction of the fluid in the pipeline changes).

[0073] The flow meter provided by the present invention is used to measure gas flow, and includes a throttling device and a rectifying device, and a built-in pressure balance chamber. The sensor measurement influencing factor is introduced for the value measured by the sensor component, and the result is compensated and corrected to improve the measurement accuracy. The present invention has the advantages of small structural size, wide measurement range, large pressure resistance range, support for bidirectional measurement, support for negative pressure measurement, good stability, high measurement accuracy, etc. The present invention can be applied to industry, energy, medical and other fields.

[0074] In one embodiment, according to Figure 1 , 6 As shown in Figures 7, the pressure balance assembly includes a pressure balance cover 6, which is arranged on the outside of the sensor assembly and is used to close the sensor assembly and the flow measurement channel to form a pressure balance chamber.

[0075] The measuring channel is formed on the inner wall of the base 2 by a component with a "┻"-shaped cross-section; the measuring channel is a "╝╚" structure, the upper part of the structure is used to connect the differential pressure sensor 5, and the lower two ends of the structure are respectively provided with ports P1 and port P2, wherein ports P1 and port P2 are located at the two ends of the throttling component 7, and are respectively used to introduce the fluid throttled by the throttling component 7 into the measuring channel for measurement by the sensor component.

[0076] A pressure balance opening 13 is provided in the measuring channel, which is used to introduce the pressure in the pipeline into the pressure balance cover to achieve pressure balance and measurement purposes; the pressure balance opening 13 can be at any one of the ports P1 and P2.

[0077] Further, combined with Figure 2-4 As shown, when the flow state of the fluid Q in the fluid channel of the base 2 through the throttling assembly 7 is static, the pressure in the flow channel is port P1 = port P2;

[0078] When the flow direction of the fluid Q in the fluid channel of the base 2 through the throttling assembly 7 is from port P1 to port P2, the pressure in the flow channel is port P1>port P2;

[0079] When the flow direction of the fluid Q in the fluid channel of the base 2 through the throttling assembly 7 is from the port P2 to the port P1 , the pressure in the measurement channel is port P1 < port P2 .

[0080] Figure 2 , 3 4 is a schematic diagram of the pressure difference measurement principle (diagram of air flow when the air flow passes through the pressure balance component); it is based on different flow directions and different pressure conditions, according to the static pressure difference at the pressure taking point of the throttling component, the air pressure in the pipe, the actual ambient atmospheric pressure and the thermodynamic temperature, to calculate the flow rate flowing through the measurement channel.

[0081] according to Figure 5-7 As shown, the measuring channel is provided with a pressure balance opening 13, and the pressure balance opening 13 is used to introduce the fluid in the flow channel into the pressure balance component;

[0082] When the pressure outside the differential pressure sensor 5 is P0, the pressure differences between the port P1, the port P2 and the outside of the differential pressure sensor 5 are (P1-P0)·S, (P2-P0)·S) ； Where S is the internal force-bearing area of ​​the differential pressure sensor structure housing;

[0083] When the pressure outside the differential pressure sensor 5 is P1, the pressure differences between the port P1, the port P2 and the outside of the differential pressure sensor 5 are 0 and (P2-P1)·S) respectively;

[0084] Wherein, S is the internal force-bearing area of ​​the differential pressure sensor structural housing.

[0085] In this scheme, when there is no pressure balance cover (pressure balance component), the pressure of the differential pressure sensor structure shell is P0 ( Figure 5 As shown), the pressure differences between port P1, port P2 and the outside of the differential pressure sensor 5 are (P1-P0)·S, (P2-P0)·S) ；

[0086] After adding the pressure balance cover, the pressure differential sensor housing is subjected to a pressure of P1 ( Figure 6 As shown), the pressure differences between port P1, port P2 and the outside of the differential pressure sensor 5 are 0 and (P2-P1)·S) respectively; wherein S is the internal force-bearing area of ​​the differential pressure sensor structure housing.

[0087] Since the values ​​of ports P1 and P2 are close and much larger than P0, the pressure difference between the differential pressure sensor housing and the port is significantly reduced after adding the pressure balance cover. The pressure sensor (piezoelectric or piezoresistive differential pressure sensor) measures the pressure value by evaluating the film deformation caused by the pressure difference between ports P1 and P2. However, when the pressure difference between ports P1, P2 and the housing exceeds the standard value, the film will be deformed or even damaged, causing measurement errors. Therefore, by designing a pressure balance cover to reduce the pressure difference between the port and the sensor housing, the applicable pressure range of the sensor can be widened and the measurement accuracy can be improved.

[0088] In one embodiment, according to Figure 1-7 As shown, the control board 8 is arranged above the sensor assembly, and the control board 8 is erected above the sensor assembly by means of a support, or is installed on the inner top surface of the outer cover 9 by means of a support;

[0089] The control board 8 is electrically connected to the sensor assembly and the external connector 10 through a wire. The outer cover 9 is disposed on the outside of the control board 8 . The external connector 10 is installed on one side of the outer cover 9 and is used to be electrically connected to the external connector 10 .

[0090] The sensor assembly comprises:

[0091] A pressure sensor 3 is located on the inner wall of the pressure balance component and is provided with one or more pressure sensors. The pressure sensor 3 passes through the pressure balance component and is connected to the control board 8 through a wire.

[0092] A temperature and humidity sensor 4 is located on the inner wall of the pressure balance component and is provided with one or more temperature and humidity sensors. The temperature and humidity sensors 4 penetrate the pressure balance component through a wire and are connected to the control board 8;

[0093] The differential pressure sensor 5 is located on the inner wall of the pressure balance component and is provided with one or more differential pressure sensors 5. The differential pressure sensor 5 passes through the pressure balance component through a wire and is connected to the control board 8. The differential pressure sensor 5 is located at the inlet and / or outlet of the measuring channel.

[0094] In this embodiment, the sensor component is used to obtain sensor data such as pressure, temperature and humidity, and pressure difference. The obtained sensor data is controlled by a control board to calculate the sensor data and output flow metering data. Finally, the data is transmitted to the outside through an external connector. The external connector is an aviation plug or terminal, a wireless transmission module, a wire, or any other method that can realize data transmission.

[0095] In one embodiment, according to Figure 1 , 8 As shown in Figure 9, the rectifying assembly 1 is located in the fluid channel in the base 2 and includes one or more groups. The rectifying assembly is used to rectify the fluid in the fluid channel.

[0096] The rectifying component 1 is formed by connecting a baffle 101, a fixing member 102, and a mesh plate 103 in sequence; or, the rectifying component 1 is formed by connecting a baffle 101, a fixing member 102, a mesh plate 103, a fixing member 102, and a mesh plate 103 in sequence.

[0097] according to Figure 1 , 8 As shown in FIG. 9 , the baffle 101 is evenly distributed with a plurality of small holes, each of which is used to divert the inflowing / outflowing fluid and introduce it into the fixing member 102. The fixing member 102 then rectifies the fluid for a second time through the mesh plate 103 and then flows into the measuring channel for fluid flow measurement.

[0098] In this solution, the thickness of the baffle 101 is about D / 8, and a plurality of small holes are evenly distributed on the baffle 101. The small holes are regular hexagonal or circular and are drafted outward. The diameter of the inscribed circle of the small holes is not greater than 0.06D, and the sum of the hole areas is greater than 30% of the cross-sectional area of ​​the pipeline.

[0099] The mesh plate 103 is a steel mesh material made of stainless steel, the mesh aperture of the mesh plate is no greater than 0.01D, and the wire diameter is about 0.004D.

[0100] In this scheme, a stable flow state is the basis for accurate measurement. The function of the rectifying structure is to reduce the airflow vortex and make the axial velocity of points at different positions on the pipe cross section tend to be consistent before the airflow passes through the throttling element.

[0101] Furthermore, the rectifier assembly 1 is installed on the inlet / outlet port of the base 2 through an end cover 11 with a channel; the end of the end cover 11 away from the base 2 is connected to a pipe joint 12, and the pipe joint 12 is used to connect a straight pipe.

[0102] Due to the existence of vortex and uneven cross-sectional flow velocity, in order to ensure measurement accuracy, existing technical flow meters usually need to maintain a straight pipe section of 8-10 times the pipe diameter at the inlet end; in the present invention, the rectifier structure is integrated at both ends of the throttling device, which can reduce the length of the straight pipe section, is suitable for more specifications of pipe diameters, and supports bidirectional measurement. It has better installability and solves industrial integration problems. In some precise environments, the straight pipe can also be replaced with a curved pipe with a compressed volume; the outermost hard porous baffle in the rectifier structure provides protection for the weak parts inside, improving the reliability of the product itself.

[0103] In one embodiment, when the pipeline is deformed, the flow rate will also change; when there is no record of pipeline replacement or maintenance, the flow meter provided by the present invention is installed on the pipeline, and when the flow meter is working, the input flow rate and the output flow rate are calibrated after installation and calibration to be v1 and v2. Under the same working conditions, when the flow measurement value is greater than the first preset value, it means that the pipeline may be deformed;

[0104] Furthermore, the present invention also includes: verifying the deformation, a vibration sensor is provided on the pipeline, when the vibration signal received by the vibration sensor is sufficient to cause the pipeline to be deformed, it is recorded as a pipeline deformation mark, and an alarm signal is sent for the user to verify it. If the pipeline is deformed, the deformed pipeline is repaired to ensure the accuracy of flow input and output.

[0105] The pipeline is provided with a photoelectric sensor. When the vibration sensor receives a vibration signal sufficient to cause deformation of the pipeline, there will often be one or more violent vibrations (damage), while one violent damage may not cause deformation of the pipeline, such as falling. At this time, by installing a miniature photoelectric sensor in the pipeline, the photoelectric sensor is used to monitor the inner wall of the pipeline, and the data collected by the photoelectric sensor is combined to further verify whether the pipeline is deformed, so as to further ensure that the flow measurement caused by the deformation of the pipeline is not inaccurate.

[0106] In this solution, the data judgment of the vibration sensor can be: when there is abnormal data, the photoelectric sensor and the calibrated flow of the input and output are checked, and when the check result is within the second preset range value, no abnormal alarm is required.

[0107] The judgment of the photoelectric sensor can be: when there is data abnormality, an alarm is directly issued; when there is no abnormality in the data, but there is an abnormality in the calibrated flow range value of the photoelectric sensor or the input and output, the data of the photoelectric sensor is used for secondary verification.

[0108] In the above situation, when there is a leak in the pipeline, the flow measurement will also deviate. Therefore, when there is no data anomaly in the vibration sensor and the photoelectric sensor; but there is an abnormality in the calibrated flow range value of the input and output, it is considered that there is a leak in the pipeline. At this time, a verification instruction is issued to remind the user to verify the leak point; thereby improving the measurement accuracy. At the same time, during the measurement process, it can also achieve the purpose of troubleshooting or alarming. Based on the detection situation, the control board can perform multiple metering data verifications, and then correct or alarm them based on the verification results.

[0109] During the correction, if there is no fault and no pressure difference change caused by deformation, the data before and after the time t (the data before and after are: the data at time t+1 and time t-1) are compared. If the data at time t-1 and time t+1 are consistent, it means that the data at time t is drift data and is recorded as invalid. The average value of t-1 and t+1 is recorded as the data at time t, thereby compensating for the erroneous drift data. However, when there are multiple data in a time concentration: there is no fault, no pressure difference change, and the data before and after time t are within the normal range; it means that the sensor component may have a fault, and the control board generates a sensor component fault code and reports it.

[0110] The rectifying component 1 in the present invention can not only rectify the fluid, but also filter the fluid, reduce or lower the presence of debris, lint and other impurities in the fluid that may damage the core components of the flow meter or affect the measurement, and can ensure the cleanliness of the throttling component 7 and the measuring channel, thereby increasing the service life of the flow meter.

[0111] In one embodiment, according to Fig.10 , 11 As shown, the throttling assembly 7 includes a low-pressure throttling assembly 7 and a high-pressure throttling assembly 7 , and the throttling passages of the low-pressure throttling assembly 7 are fewer than the throttling passages of the high-pressure throttling assembly 7 .

[0112] The blocking effect of the throttling component causes the fluid to generate a pressure difference at the front and rear ends of the throttling component. The throttling parts of traditional differential pressure flowmeters include orifice plates, venturi tubes, nozzles and other structures. After nearly a hundred years of research, a large amount of empirical data has been accumulated and standardization has been achieved, but they all have their own shortcomings, such as small range, complex processing, poor repeatability, or easy clogging. The throttling component in the present invention has the advantages of good repeatability, stable measurement, high accuracy, simple structure, high reliability, and no moving parts.

[0113] In one embodiment, the present invention also includes the following technical solution: performing temperature and air pressure correction on the fluid to be measured in the measuring channel:

[0114] Step 1, use formula 1 to obtain the gas mass flow rate in the measurement channel:

[0115]

[0116] Wherein, C is the outflow coefficient; β is the ratio of the diameter of the opening area of ​​the throttling component 7 to the diameter of the pipe cross-sectional area; Δp is the static pressure difference Pa at the pressure taking point of the throttling component 7; ε is the expandability coefficient; p1 is the gas density before the throttling component 7; where p and Δp are both actual measurements; ε is a statistical quantity;

[0117] Furthermore, A1 is the diameter of the pipe cross-sectional area D; A0 is the diameter of the opening area of ​​the throttling component 7;

[0118] Step 2, obtain the gas density in the flow channel, and use Formula 2 to correct for temperature and pressure:

[0119]

[0120] Among them, ρ n P is the gas density under standard conditions (the air density at 0°C and standard atmospheric pressure is 1.293 kg / m3); n is the gas pressure under standard conditions (101325Pa); T n is the thermodynamic temperature of gas under standard conditions (0°C, 273.15K); P is the actual gas pressure; T is the actual thermodynamic temperature;

[0121] Step 3, calculate and obtain the corrected gas flow rate using formula 3:

[0122]

[0123] Wherein, Δp is the static pressure difference at the pressure taking point of the throttling component 7; P in is the air pressure inside the tube; P is the actual ambient atmospheric pressure; T is the actual gas thermodynamic temperature; k is the flow coefficient.

[0124] Specifically, the derivation process of formula 3 is: substitute the temperature and pressure correction formula in formula 2 into formula 1 to obtain the corrected gas flow formula; substitute formula 2 into formula 1 to obtain: Simplified to Formula 3, Q ATP1 is the gas flow rate.

[0125] Step 4, calculating the density of the mixed gas according to the content of each gas component; wherein the mixed gas is dry air with oxygen, carbon dioxide and water vapor added;

[0126]

[0127] Wherein, Δp is the static pressure difference at the pressure taking point of the throttling component 7; P in is the air pressure in the tube; P is the actual ambient atmospheric pressure; T is the actual thermodynamic temperature; φ is the actual relative humidity; G is the actual carbon dioxide concentration; FIO2 is the actual oxygen concentration; F(T) is the percentage of air saturated with water vapor; k is the flow coefficient.

[0128] When several known gases are mixed, the density of the mixed gas can be calculated based on the content of each gas component.

[0129] Taking the medical use scenario as an example, the mixed gas is dry air with oxygen, carbon dioxide, and water vapor added:

[0130] Since the density of a gas is proportional to its relative molecular weight at the same temperature and pressure, the density of various gases has the following relationship:

[0131]

[0132]

[0133]

[0134] in, is the oxygen density, M Air is the relative molecular weight, is the density of nitrogen, M Ar is the density of argon gas, is the carbon dioxide gas density;

[0135] At temperature T, the percentage of saturated water vapor in the air is: f(T)(273.15K≤T≤373.15K); according to statistical data fitting:

[0136] f(T)=0.00000072300413880654T 3 -

[0137] 0.000595041483584363T 2 +0.163867651715586T-15.0930949796368

[0138] If the oxygen concentration is FIO2 and the relative humidity is φ, then it can be assumed that the mixed gas is a mixture of dry air, incremental water vapor, incremental pure oxygen, and incremental carbon dioxide; the proportion of water vapor is φF(T), and the proportion of carbon dioxide is G;

[0139] Assuming the proportion of incremental pure oxygen is x, the proportion of dry air is: 1-xG-φF(T), and the value of oxygen concentration FIO2 is: (incremental pure oxygen + O2 in dry air) / total volume.

[0140] Then we have:

[0141] FIO2=x+ (1-xG-φF(T)) ×0.20948 Formula (5)

[0142] FIO2=0.79052x+0.20948× (1-G-φF(T)) Formula (6)

[0143] have to:

[0144]

[0145] ρ=1.105247x·ρ g +0.6224φF(T)·ρ g +1.5204G·ρ g

[0146] +[1-xG-φF(T)]ρ g

[0147] Then we have:

[0148] ρ=[0.9721+0.133164FIO2+0.5483G-0.3497φF(T)]ρ g

[0149] Formula (7)

[0150] Substituting formula (7) into formula (2), we have:

[0151]

[0152] Substituting formula (8) into formula 1 and formula (3), we have

[0153]

[0154] By simplifying formula (9), we get formula (4), and using the coefficient detection method to measure the k value, we can get the flow equation.

[0155] In the present invention, Figure 13-14 This is an actual sample diagram. Based on the structural technical solution and flow calculation solution proposed in this invention, the flow rate is tested. Figure 1 , 12 All are structural principle diagrams, Figure 2-7 To explain the measurement principle, according to Figure 15-Figure 24 As shown, the present invention performs multiple measurements under the environment of 0-750Kpa, and compares the corrected and uncorrected flow measurement results based on the measurement results, wherein the flow measurement formula is calculated using formula (4), wherein the k value is 3.58 and 3.5757, and the test conditions are: air without condensed water, ambient temperature 22°C; measuring pipe diameter: 8mm before and after;

[0156] According to the 8 sets of flow test data with output open at 0KPa, 100KPa, 200KPa, 300KPa, 400KPa, 500KPa, 600KPa, and 750KPa internal pressure, the test results of this industrial flow meter against the TS I gas flow analyzer are as follows:

[0157] 1. Under the condition of output open pressure, the flow measurement deviation rate is within the range of 27-445L / min: <±2% of the actual measured value.

[0158] 2. Under the pressure condition of 100KPa, the flow measurement deviation rate is within the range of 38~244L / min: <±1.5% of the actual measured value.

[0159] 3. Under the pressure condition of 200KPa, the flow measurement deviation rate is within the range of 35~367L / min: <±3% of the actual measured value.

[0160] 4. Under the pressure condition of 300KPa, the flow measurement deviation rate is within the range of 30~438L / min: <±5% of the actual measured value.

[0161] 5. Under the pressure condition of 400KPa, the flow measurement deviation rate is within the range of 34~391L / min: <±3% of the actual measured value.

[0162] 6. Under the pressure condition of 500KPa, the flow measurement deviation rate in the range of 24~380L / min is: <±5% of the actual measured value.

[0163] 7. Under the pressure condition of 600KPa, the flow measurement deviation rate is within the range of 17~324L / min: <±4% of the actual measured value.

[0164] 8. Under the pressure condition of 750KPa, the flow measurement deviation rate is within the range of 22~258L / min: <±5% of the actual measured value.

[0165] Based on the above results, within the pressure range of 0 to 750KPa: 32 to 244L / min, the flow measurement deviation rate is: <±5% of the actual measured value.

[0166] In summary, the present invention can have the following technical effects:

[0167] Through the structural design of the differential pressure flowmeter, the flow measurement range is increased, and the ability of bidirectional measurement and negative pressure measurement is achieved, which improves the measurement stability and accuracy; it can solve the existing problems of differential pressure flowmeters under different pressures and can perform stable and accurate measurements under conditions of -0.1MPa to 1Mpa;

[0168] In the present invention, the innovation of the rectifier component 1 solves the major problems of inaccurate measurement and limited measurement caused by gas source interference of the general differential pressure flowmeter, solves the data stability and consistency problems of piezoelectric and piezoresistive differential pressure sensors under large pressure changes, thereby improving the measurement accuracy; the built-in pressure sensor can realize negative pressure flow measurement, thereby realizing a bidirectional measurement function (forward and reverse); the design of the rectifier component 1 solves the problem of gas flow state stability, and compared with the existing structure, it does not require an excessively long straight pipe section and can be compatible with smaller diameter piping; it has better installability and solves the problem of industrial integration;

[0169] The pressure balance assembly (pressure balance cover 6) can well solve the high-sensitivity positive and negative pressure and bidirectional flow measurement, solve the measurement problems of small flow (0.2L / min) and large flow (>3000L / min), and has low pressure loss; the pressure balance structure enables the flow meter to measure the fluid stably and accurately in different pressure environments, which has obvious advantages over similar products in the world;

[0170] The flow correction scheme of the present invention takes into account the influencing factors of fluid flow measurement, including internal and external pressures, pressure difference, temperature, humidity and gas composition; and is applicable to all differential pressure flow meters.

[0171] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A stable flow, pressure-resistant and highly sensitive differential pressure flowmeter, characterized in that: include: A base (2), wherein a sensor component is arranged outside the base (2); a throttling component (7) is arranged inside the base (2); the throttling component (7) and the sensor component are connected via a measuring channel and are used to introduce the fluid in the base (2) into the measuring channel for flow measurement; The pressure balance component comprises a pressure balance cover (6), wherein the pressure balance cover (6) is arranged outside the sensor component and is used to seal the sensor component and the flow measurement channel; The measuring channel is formed on the inner wall of the base (2) by a member having a "┻"-shaped cross section; the measuring channel is a "╝╚" structure, the upper part of the structure is used to connect the differential pressure sensor (5), and the lower two ends of the structure are respectively provided with a port P1 and a port P2, wherein the ports P1 and the ports P2 are located at the two ends of the throttling component (7) and are respectively used to introduce the fluid throttled by the throttling component (7) into the measuring channel for measurement by the sensor component; The measuring channel is provided with a pressure balance opening, and the pressure balance opening is used to introduce the fluid in the flow channel into the pressure balance component; When the pressure outside the differential pressure sensor (5) is P0, the pressure differences between the port P1, the port P2 and the outside of the differential pressure sensor (5) are (P1-P0)·S, (P2-P0)·S) respectively; When the air pressure outside the differential pressure sensor (5) is P1, the pressure differences between the port P1, the port P2 and the outside of the differential pressure sensor (5) are 0 and (P2-P1)·S) respectively; Wherein, S is the internal force-bearing area of ​​the differential pressure sensor structural housing.

2. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 1, characterized in that: A control panel (8) is arranged above the sensor assembly. The control panel (8) is mounted above the sensor assembly by means of a support column, or is installed on the inner top surface of the outer cover (9) by means of a support column; The control panel (8) is electrically connected to the sensor assembly and the external connector (10) through a wire. The outer cover (9) is arranged on the outside of the control panel (8). The external connector (10) is installed on one side of the outer cover (9) and is used to be electrically connected to the external connector (10).

3. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 1, characterized in that: The sensor assembly comprises: A pressure sensor (3) is located on the inner side wall of the pressure balance component and is provided with one or more pressure sensors. The pressure sensor (3) passes through the pressure balance component through a wire and is connected to the control board (8); A temperature and humidity sensor (4) is located on the inner wall of the pressure balance component and is provided with one or more temperature and humidity sensors. The temperature and humidity sensors (4) penetrate the pressure balance component through a wire and are connected to the control board (8); A pressure differential sensor (5) is located on the inner side wall of the pressure balance component and is provided with one or more pressure differential sensors (5). The pressure differential sensor (5) passes through the pressure balance component through a wire and is connected to the control board (8); wherein the pressure differential sensor (5) is located at the inlet and / or outlet of the measuring channel.

4. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 1, characterized in that: The rectifying assembly (1) is located in a fluid channel in a base (2) and comprises one or more groups, wherein the rectifying assembly is used to rectify the fluid in the fluid channel.

5. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 4, characterized in that: The rectifying component (1) is formed by connecting a baffle (101), a fixing member (102), and a mesh plate (103) in sequence; or, the rectifying component (1) is formed by connecting a baffle (101), a fixing member (102), a mesh plate (103), a fixing member (102), and a mesh plate (103) in sequence.

6. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 5, characterized in that: The baffle (101) is evenly distributed with a plurality of small holes, each of which is used to split the inflowing / outflowing fluid and introduce it into the fixing member (102). The fixing member (102) then performs secondary rectification on the fluid through the mesh plate (103) and then flows into the measurement channel for fluid flow measurement.

7. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 4, characterized in that: The rectifying assembly (1) is installed on the inlet / outlet port of the base (2) through an end cover (11) with a channel; the end of the end cover (11) away from the base (2) is connected to a pipe joint (12), and the pipe joint (12) is used to connect a straight pipe.

8. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 1, characterized in that: When the flow direction of the fluid Q in the fluid channel of the base (2) through the throttling assembly (7) is static, the pressure in the flow channel is port P1 = port P2; When the flow direction of the fluid Q in the fluid channel of the base (2) through the throttling assembly (7) is from port P1 to port P2, the pressure in the flow channel is port P1>port P2; When the flow direction of the fluid Q in the fluid channel of the base (2) through the throttling assembly (7) is from port P2 to port P1, the pressure in the measurement channel is port P1 < port P2.

9. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 1, characterized in that: The throttling assembly (7) comprises a low-pressure throttling assembly (7) and a high-pressure throttling assembly (7), and the throttling passage of the low-pressure throttling assembly (7) is less than the throttling passage of the high-pressure throttling assembly (7).

10. The steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter according to claim 1, characterized in that: Perform temperature and pressure correction on the fluid to be measured in the measuring channel: Step 1: Use formula (1) to obtain the gas mass flow rate in the measurement channel: Wherein, C is the outflow coefficient; β is the ratio of the diameter of the opening area of ​​the throttling component (7) to the diameter of the cross-sectional area of ​​the pipeline; Δp is the static pressure difference (Pa) at the pressure taking point of the throttling component (7); ε is the expandability coefficient; ρ1 is the gas density before the throttling component (7); wherein ρ and Δp are both actual measurements; ε is a statistical quantity; Step 2, obtain the gas density in the flow channel, use formula (2) and correct it for temperature and pressure: Among them, ρ n is the gas density under standard conditions; P n is the gas pressure under standard conditions; T n is the thermodynamic temperature of gas under standard conditions; P is the actual gas pressure; T is the actual thermodynamic temperature; Step 3, use formula (3) to calculate and obtain the corrected gas flow: Wherein, Δp is the static pressure difference at the pressure taking point of the throttling component (7); P in is the air pressure inside the tube; P is the actual ambient atmospheric pressure; T is the actual gas thermodynamic temperature; k is the flow coefficient.

11. A steady-flow, pressure-resistant, high-sensitivity differential pressure flowmeter as claimed in claim 10, characterized in that: The density of the mixed gas is calculated according to the content of each gas component; wherein the mixed gas is dry air with oxygen, carbon dioxide and water vapor added; Wherein, Δp is the static pressure difference at the pressure taking point of the throttling component (7); P in is the air pressure in the tube; P is the actual ambient atmospheric pressure; T is the actual thermodynamic temperature; φ is the actual relative humidity; G is the actual carbon dioxide concentration; FIO2 is the actual oxygen concentration; F(T) is the percentage of air saturated with water vapor; k is the flow coefficient.

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