A gas wobble plate flowmeter and its real-time accuracy monitoring method

Abstract

One technical scheme of the present application is to provide a gas rotary piston flowmeter. Another technical scheme of the present application is to provide a real-time accuracy monitoring method for the gas rotary piston flowmeter. The present application adopts a method that can monitor the pressure difference between the inlet and outlet of the gas rotary piston flowmeter in real time, thereby reflecting the degree of contamination in the flowmeter cavity. Then, according to the measured value of the pressure difference between the inlet and outlet, the intelligent control part is modeled and calculated to calculate the measurement accuracy deviation of the gas rotary piston flowmeter. If the measurement accuracy deviation reaches one time of the maximum allowable error, an alarm prompt information will be uploaded through the liquid crystal page or through wired remote transmission, wireless remote transmission and the like to inform the user to maintain or repair the gas rotary piston flowmeter, thereby avoiding the loss of the user.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of to measure gas flow's waist wheel flowmeter (also can be called Roots flowmeter), also relates to a kind of to the accuracy of the waist wheel flowmeter is monitored in real time test method, belongs to gas flowmeter measurement technical field. BACKGROUND

[0002] Gas waist wheel flowmeter is the volumetric flowmeter of accurate measurement gas passing, with high measurement accuracy, with high precision, wide range, high reliability, long life and the like.Gas waist wheel flowmeter is suitable for the measurement of gas flow in closed pipeline, can be widely used in natural gas, coal gas, inert gas, air and other non-corrosive gas flow measurement, is the ideal flow measurement device of petroleum, chemical industry, industry, civil boiler, gas pressure regulating tank, scientific research and other departments.As a kind of traditional volumetric instrument, gas waist wheel flowmeter uses the working principle of rotating fixed displacement, and its accuracy relies on a pair of precision machining rotor and solid measurement chamber, to ensure permanent non-adjustable high accuracy.Gas waist wheel flowmeter's measurement accuracy is not affected by gas specific gravity, pressure and flow variation, especially suitable for high-precision, medium-flow measurement range, with compact and solid structure, inlet does not need straight pipe section and the like, thus suitable for installation in narrow environment.

[0003] The measurement principle of gas waist wheel flowmeter is as follows: two 8-shaped rotors (rotor can also be called "waist wheel") rotating in opposite directions are placed in a solid measurement chamber.Precisely machined adjusting gear makes the rotors maintain correct relative position.The best working gap is maintained between the two rotors and between the rotor and the shell, which provides continuous non-contact sealing.

[0004] Two 8-shaped rotors are defined as upper rotor and lower rotor respectively, combined Figures 1A-1D Further explain the measurement principle of gas waist wheel flowmeter:

[0005] As Figure 1A shown, when the lower rotor rotates to the horizontal position in counterclockwise direction, gas enters the space between the shell and the rotor;As Figure 1B shown, the lower rotor rotates to the horizontal position, and a fixed volume of gas is stored in the bottom of the measurement chamber;As Figure 1C shown, when the upper rotor and the lower rotor continue to rotate, the gas in the bottom of the measurement chamber is discharged;As Figure 1D shown, at the same time as the above process, the upper rotor rotates to the horizontal position in clockwise direction, and the same volume of gas as the bottom of the measurement chamber is stored in the upper part of the measurement chamber.Each pair of rotors in the gas waist wheel flowmeter rotates one revolution, and four equal volumes of gas are discharged.

[0006] As the gas flows, a differential pressure is generated at the inlet and outlet of the gas rotameter, which acts on the rotors connected by high-precision, synchronous gears, generating a torque. The torque acts on a pair of rotors in turn, causing them to rotate. There is no contact between the housing and the rotors, and thus the measurement chambers formed between the housing and the rotors are periodically filled and emptied by the gas. The number of rotations of the rotors is directly proportional to the volume of the gas passing through the gas rotameter.

[0007] There will be additional gas flow in the inevitable gaps between the rotors and the housing and between the two rotors, resulting in a leakage flow not included in the four volumes, which in turn forms the difference between the indicated flow (i.e. the flow value displayed by the counting device of the measured gas rotameter) and the true total flow (the flow value obtained by the standard measurement detection device), defined as the error ε, expressed as formula (1) below:

[0008]

[0009] In formula (1), Q m represents the cumulative indicated flow of the measured gas rotameter, with the unit of m 3 ; Q s represents the cumulative true flow obtained by the standard measurement detection device, with the unit of m 3 ; T s , T m are the gas temperatures at the standard measurement detection device and the measured gas rotameter, respectively, with the unit of K; P s , P m are the absolute pressures at the standard measurement detection device and the measured gas rotameter, respectively, with the unit of Pa.

[0010] Because the gas rotameter has certain gaps between the two rotors, between the rotors and the housing, and between the rotors and the side plates, and because the gas entering the gas rotameter contains particulate impurities such as dust during use, the impurities will gradually accumulate over time as the gas rotameter operates, affecting the flexibility of the rotor rotation, slowing down the rotor rotation, and thus affecting the measurement accuracy of the gas rotameter, causing gas loss and unnecessary economic losses to the user. SUMMARY

[0011] The purpose of the present application is to effectively monitor the measurement accuracy of the flowmeter in real time.

[0012] To address the aforementioned technical problems, one technical solution of the present invention provides a gas rotary flow meter, comprising a flow meter body, wherein a standard metrological detection device is fixed on the rotary housing of the flow meter body. The standard metrological detection device obtains the pressure difference between the inlet and outlet of the gas rotary flow meter through a differential pressure sensor module. This pressure difference is further defined as a pressure loss value. A mathematical model is then established within the standard metrological detection device based on a pressure loss curve, whereby the pressure loss curve represents the relationship between the pressure loss value and the gas flow rate through the gas rotary flow meter. After obtaining the real-time gas flow rate, the standard metrological detection device calculates the theoretical value of the pressure loss using the mathematical model. The standard metrological detection device uses the ratio of the theoretical pressure loss value to the measured pressure loss value obtained through the differential pressure sensor module to determine whether the pressure loss of the gas rotary flow meter exceeds the standard. If it does, an alarm is issued.

[0013] Preferably, a pressure tapping connector is provided at the air inlet and air outlet of the flow meter body, and the two pressure tapping connectors are connected to the differential pressure sensor module on the standard metrology and testing device through their respective air pipes. The differential pressure sensor module obtains the gas pressure at the air inlet and the gas pressure at the air outlet of the flow meter body through the two pressure tapping connectors, obtains the pressure loss value, and sends the pressure loss value to the standard metrology and testing device.

[0014] Preferably, a switching valve is provided at the interface between the two air tubes and the differential pressure sensor module, and the corresponding air tubes are opened or closed by using the switching valves.

[0015] Preferably, the measurement error ε is expressed as follows:

[0016]

[0017] In the formula, Q s Q represents the cumulative actual flow rate obtained through the standard metering and testing device. s =Q m +Q X Q m Q represents the cumulative indicated flow rate of the gas measured by the rotary valve flow meter. X Indicates the leaked traffic; T s T m These are the gas temperatures inside the standard metering and testing device and at the gas rotary flow meter being measured, respectively; P s P m These are the absolute pressures inside the standard metering and testing device and at the rotary flow meter of the gas being measured, respectively.

[0018] The greater the pressure loss value, the more flow is leaked; conversely, the smaller the pressure loss value, the less flow is leaked.

[0019] Furthermore, the pressure loss value is directly proportional to the gas flow rate, and the mathematical model is established based on this proportional relationship.

[0020] Preferably, the mathematical model established by the standard metrology and testing device is as follows:

[0021] Δp=C1+C2×Q

[0022] In the formula, Δp represents the theoretical value of pressure loss; Q represents the gas flow rate; C1 and C2 represent linearity coefficients, which are empirical values.

[0023] Another technical solution of the present invention is to provide a method for real-time accuracy monitoring of a gas rotary flow meter, characterized by comprising the following steps:

[0024] When the gas rotary flow meter is working, gas enters from the inlet of the rotary wheel housing. The airflow does work on the rotary wheel rotor assembly inside the rotary wheel housing, driving the rotary wheel rotor assembly to rotate. During this process:

[0025] The differential pressure sensor module obtains the measured value Δp of the pressure loss. a The gas flow rate is then transmitted to the standard metrology and testing device. The standard metrology and testing device simultaneously detects the gas flow rate in real time and obtains the theoretical value of pressure loss Δp based on the established mathematical model. The mathematical model is based on the pressure loss curve, which is used to represent the relationship between the pressure loss value and the gas flow rate passing through the gas rotary flow meter.

[0026] The theoretical pressure loss Δp and the measured pressure loss Δp are calculated by the standard metrological testing device. a The ratio is used to determine whether the pressure loss of the gas rotary flow meter exceeds the standard.

[0027] Preferably, the mathematical model is as follows:

[0028] Δp=C1+C2×Q

[0029] In the formula, Δp represents the theoretical value of pressure loss; Q represents the gas flow rate; C1 and C2 represent linearity coefficients, which are empirical values.

[0030] Preferably, when the standard metering and detection device detects the gas flow rate in real time at Q... max With 0.7Q max At that time, if Δp a If / Δp>2, the pressure loss of the gas rotary flow meter is determined to be abnormal, and the standard metering and testing device will issue an alarm signal; otherwise, the pressure loss of the gas rotary flow meter is determined to be normal. Where Q maxrepresents the maximum gas flow of the gas rotary piston flowmeter; when the standard metering detection device detects that the gas flow is between 0.7Q max and 0.2Q max , if Δp a / Δp>3, it is determined that the pressure loss of the gas rotary piston flowmeter is abnormal, and the standard metering detection device sends an alarm signal, otherwise it is determined that the pressure loss of the gas rotary piston flowmeter is normal.

[0031] Preferably, when the standard metering detection device sends an alarm signal, the corresponding alarm mark is displayed locally.

[0032] Preferably, when the standard metering detection device sends an alarm signal, it is uploaded to the remote monitoring management platform through the communication protocol.

[0033] The present application adopts a method that can monitor the pressure difference between the inlet and outlet of the gas rotary piston flowmeter in real time, thereby reflecting the degree of contamination in the flowmeter cavity. Then, according to the measured value of the pressure difference between the inlet and outlet, the intelligent control part is modeled and calculated to calculate the metering accuracy deviation of the gas rotary piston flowmeter. If the metering accuracy deviation reaches one time of the maximum allowable error, an alarm prompt information is uploaded through the liquid crystal page prompt or through wired remote transmission, wireless remote transmission and other ways to inform the user to maintain or repair the gas rotary piston flowmeter, thereby avoiding user loss. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figures 1A-1D The working principle of the gas rotary piston flowmeter is illustrated, wherein, Figures 1A-1D four different positions of the rotor in the gas rotary piston flowmeter are illustrated respectively;

[0035] Figure 2A and Figure 2B is a structural schematic diagram of the gas rotary piston flowmeter in the present embodiment;

[0036] Figure 3 is a working principle diagram of the gas rotary piston flowmeter in the present embodiment;

[0037] Figure 4 is a pressure loss curve diagram, wherein the pressure loss is the pressure difference between the inlet and outlet of the gas rotary piston flowmeter. DETAILED DESCRIPTION

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are merely intended to assist those skilled in the art in understanding the principles and knowledge of the present invention, and are not intended to limit the scope of the invention, nor should they be considered as limiting the application scenarios of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various modifications or alterations to the invention, but any variations, changes, and transformations made to the embodiments based on the principles and spirit of the invention also fall within the scope defined by the appended claims. And it is obvious that this specification only uses preferred embodiments as examples, and does not need to exhaustively describe all embodiments.

[0039] like Figure 2A and Figure 2B As shown, the gas rotary flow meter disclosed in this embodiment includes a flow meter body, on which an intelligent volume corrector 1 is fixed. A pressure tapping connector 2 is provided at both the inlet and outlet of the flow meter body. The two pressure tapping connectors 2 are connected to a differential pressure sensor module 5 on the intelligent volume corrector 1 via their respective air pipes 3. The differential pressure sensor module 5 obtains the gas pressure at the inlet and outlet of the flow meter body through the two pressure tapping connectors 2, thus obtaining the pressure difference between the inlet and outlet of the gas rotary flow meter. A switching valve 4 is provided at the interface between the two air pipes 3 and the differential pressure sensor module 5, which is used to open or close the corresponding air pipes 3. It should be noted that the intelligent volume corrector 1 and its differential pressure sensor module 5 are conventional devices well known to those skilled in the art and will not be described in detail here.

[0040] Similar to conventional gas rotary flow meters, such as Figure 3 As shown, in this embodiment, the waist wheel housing 6 is provided with a waist wheel rotor assembly 7, which consists of a pair of waist wheels arranged vertically.

[0041] The pressure difference between the inlet and outlet of the gas rotary flow meter is further defined as the pressure loss value. The intelligent volume correction instrument 1 then measures the pressure loss value in real time using the differential pressure sensor module 5. This pressure loss value is compared with the built-in typical pressure loss curve based on the gas rotary flow meter (e.g., ...). Figure 4 By comparing the mathematical model (as shown) with the current gas rotary flow meter's error, the accuracy of the instrument can be determined to meet the standard.

[0042] As mentioned above, gaps exist between the two impellers of the gas impeller flow meter, between the impeller and the impeller housing 6, and between the impeller and the side plate. Therefore, during the measurement of fluid volume, leakage will occur from these gaps, resulting in a measurement error ε. The flow loss due to leakage is considered the main source of the measurement error ε. In this embodiment, the measurement error ε is expressed as the following formula (2):

[0043]

[0044] In equation (2), Q s Q represents the cumulative actual flow rate obtained through the intelligent volume corrector 1. s =Q m +Q X Q m Q represents the cumulative indicated flow rate of the gas measured by the rotary valve flow meter. X Indicates the leaked traffic; T s T m These are the gas temperatures inside the intelligent volume corrector 1 and at the gas rotary flow meter, respectively; P s P m These are the absolute pressures inside the intelligent volume corrector 1 and at the gas rotary flow meter being measured, respectively.

[0045] The loss of flow rate due to leakage mainly depends on the pressure difference between the inlet and outlet of the instrument, i.e., the pressure loss. We found that the greater the pressure loss value, the greater the leakage flow rate; conversely, the smaller the pressure loss value, the less the leakage flow rate. For gas rotary flow meters, the pressure loss value corresponding to different gas flow rates can be measured using standard metering and testing devices such as intelligent volume correctors, and then a pressure loss curve can be fitted to obtain the curve. Figure 4 As shown.

[0046] According to the pressure loss curve of the gas rotary flow meter, the pressure loss value is proportional to the gas flow rate. Assuming that the pressure loss and flow rate have a linear relationship, the mathematical model shown in equation (3) is established as follows:

[0047] Δp=C1+C2×Q (3)

[0048] In equation (3), Δp represents the theoretical value of pressure loss in Pa; Q represents the gas flow rate in m³ / s. 3 / h; C1 and C2 represent linear coefficients, which are empirical values.

[0049] When the flow meter is working, gas enters through the inlet of the rotary wheel housing 6. The airflow does work on the rotary wheel rotor assembly 7, driving it to rotate. This creates a pressure loss at the inlet and outlet of the rotary wheel housing 6, which is proportional to the flow rate. The gas pressure is transmitted to the differential pressure sensor module 5 through the gas pipe 3, thus obtaining the measured value Δp of the pressure loss. a Measured value of pressure loss Δp aThe pressure is transmitted to the intelligent volume corrector 1 via the communication protocol of the differential pressure sensor module 5. Simultaneously, the intelligent volume corrector 1 detects the gas flow rate in real time (a conventional technique used by those skilled in the art, and will not be elaborated upon here), and obtains the theoretical value Δp of the pressure loss based on the mathematical model established by formula (3). The intelligent volume corrector 1 further calculates the theoretical value Δp of the pressure loss and the measured value Δp of the pressure loss. a The ratio of the pressure loss of the gas rotary valve flow meter to the pressure loss of the gas flow meter can be used to determine whether the pressure loss exceeds the standard. Experimental data shows that when the intelligent volume corrector 1 detects the gas flow rate within Q... max With 0.7Q max At that time, if Δp a If / Δp>2, the pressure loss of the gas rotary flow meter is determined to be abnormal, and the intelligent volume corrector 1 issues an alarm signal; otherwise, the pressure loss of the gas rotary flow meter is determined to be normal, where Q max This indicates the maximum gas flow rate of the gas rotary valve flow meter; when the intelligent volume corrector 1 detects a gas flow rate of 0.7Q in real time... max With 0.2Q max When Δp a If / Δp>3, the pressure loss of the gas rotary flow meter is determined to be abnormal, and the intelligent volume corrector 1 issues an alarm signal; otherwise, the pressure loss of the gas rotary flow meter is determined to be normal.

[0050] When the intelligent volume corrector 1 issues an alarm signal, it can display a sign indicating that maintenance is required on the LCD screen of the intelligent volume corrector 1, or it can upload the signal to the monitoring and management platform via RS485 protocol to prompt the user to perform maintenance or repair on the gas rotary flow meter.

Claims

1. A gas rotary flow meter, comprising a flow meter body, wherein a standard measuring and testing device is fixed on the rotary housing of the flow meter body, characterized in that, The standard metrology and testing device obtains the pressure difference between the inlet and outlet of the gas rotary flow meter through a differential pressure sensor module. This pressure difference is further defined as the pressure loss value. A mathematical model is then established within the standard metrology and testing device based on the pressure loss curve, which represents the relationship between the pressure loss value and the gas flow rate through the gas rotary flow meter. After obtaining the real-time gas flow rate, the standard metrology and testing device calculates the theoretical value of the pressure loss using the mathematical model. The device then uses the ratio of the theoretical pressure loss value to the measured pressure loss value obtained through the differential pressure sensor module to determine whether the pressure loss of the gas rotary flow meter exceeds the standard. If it does, an alarm is issued. The measurement error ε can be expressed as follows: In the formula, Q s Q represents the cumulative actual flow rate obtained through the standard metering and testing device. s =Q m +Q X Q m Q represents the cumulative indicated flow rate of the gas measured by the rotary valve flow meter. X Indicates the leaked traffic; T s T m These are the gas temperatures inside the standard metering and testing device and at the gas rotary flow meter being measured, respectively; P s P m These are the absolute pressures inside the standard metering and testing device and at the rotary flow meter of the gas being measured, respectively. The greater the pressure loss value, the more flow is leaked; conversely, the smaller the pressure loss value, the less flow is leaked. Furthermore, the pressure loss value is directly proportional to the gas flow rate, and the mathematical model is established based on this proportional relationship.

2. The gas rotary flow meter as described in claim 1, characterized in that, A pressure tapping connector is provided at the air inlet and air outlet of the flow meter body. The two pressure tapping connectors are connected to the differential pressure sensor module on the standard metrology and testing device through their respective air pipes. The differential pressure sensor module obtains the gas pressure at the air inlet and the gas pressure at the air outlet of the flow meter body through the two pressure tapping connectors, obtains the pressure loss value, and sends the pressure loss value to the standard metrology and testing device.

3. A gas rotary flow meter as described in claim 2, characterized in that, A switching valve is provided at the interface between the two air tubes and the differential pressure sensor module, and the corresponding air tubes are opened or closed by using the switching valves.

4. A gas rotary flow meter as described in claim 1, characterized in that, The mathematical model established by the standard metrology and testing device is shown in the following equation: Δp=C1+C2×Q In the formula, Δp represents the theoretical value of pressure loss; Q represents the gas flow rate; C1 and C2 represent linearity coefficients, which are empirical values.

5. A method for real-time accuracy monitoring of a gas rotary flow meter as described in claim 1, characterized in that, Includes the following steps: When the gas rotary flow meter is working, gas enters from the inlet of the rotary wheel housing. The airflow does work on the rotary wheel rotor assembly inside the rotary wheel housing, driving the rotary wheel rotor assembly to rotate. During this process: The differential pressure sensor module obtains the measured value Δp of the pressure loss. a The gas flow rate is then transmitted to the standard metrology and testing device. The standard metrology and testing device simultaneously detects the gas flow rate in real time and obtains the theoretical value of pressure loss Δp based on the established mathematical model. The mathematical model is based on the pressure loss curve, which is used to represent the relationship between the pressure loss value and the gas flow rate passing through the gas rotary flow meter. The theoretical pressure loss Δp and the measured pressure loss Δp are calculated by the standard metrological testing device. a The ratio is used to determine whether the pressure loss of the gas rotary flow meter exceeds the standard; The mathematical model is shown in the following equation: Δp=C1+C2×Q In the formula, Δp represents the theoretical value of pressure loss; Q represents the gas flow rate; C1 and C2 represent linearity coefficients, which are empirical values.

6. The real-time accuracy monitoring method as described in claim 5, characterized in that, When the standard metering and testing device detects the gas flow rate in real time at Q max With 0.7Q max At that time, if Δp a If / Δp>2, the pressure loss of the gas rotary flow meter is determined to be abnormal, and the standard metering and testing device will issue an alarm signal; otherwise, the pressure loss of the gas rotary flow meter is determined to be normal. Where Q max This indicates the maximum gas flow rate of the gas rotary valve flow meter; when the standard metering and testing device detects a gas flow rate of 0.7Q in real time. max With 0.2Q max When Δp a If / Δp>3, the pressure loss of the gas rotary flow meter is determined to be abnormal, and the standard metering and testing device will issue an alarm signal; otherwise, the pressure loss of the gas rotary flow meter is determined to be normal.

7. The real-time accuracy monitoring method as described in claim 6, characterized in that, When the standard metrology and testing device issues an alarm signal, the corresponding alarm indicator is displayed locally.

8. The real-time accuracy monitoring method as described in claim 6, characterized in that, When the standard metrology and testing device issues an alarm signal, it uploads the signal to the remote monitoring and management platform via a communication protocol.

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