Flow control method and flow control device based on differential pressure type flowmeter

Abstract

The embodiment of the invention provides a flow control method and device based on a differential pressure type flowmeter, and the method comprises the steps: enabling the differential pressure type flowmeter to be connected with a gas path of a standard flow device in series, enabling the upstream of a laminar flow element of the differential pressure type flowmeter to be provided with a pressure sensor, and enabling the interior of the laminar flow element to be provided with a differential pressure sensor and a temperature sensor; the differential pressure between the upstream and the downstream of the laminar flow element is controlled to reach a plurality of different differential pressure values, and flow values and viscosity coefficients of a plurality of groups of corresponding differential pressure type flow meters are obtained based on the calibration value of the standard flow device and the measurement values of the pressure sensor, the differential pressure sensor and the temperature sensor; fitting an instrument coefficient on the basis of a least square method for the flow values of the multiple groups of differential pressure type flowmeters and the ratios of the corresponding differential pressure values and the viscosity coefficients; and the target flow is obtained, and the required control differential pressure value is calculated based on the instrument coefficient and the viscosity coefficient at the current temperature, so that the target flow is achieved through the control differential pressure value.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the technical field of gas path control, and in particular, to a flow control method and a flow control device based on a differential pressure flow meter. Background Art

[0002] In the modern industrial field, accurate control of the flow of gases and liquids is crucial to production efficiency, product quality and the stability of equipment operation. Among the many flow control technologies, differential pressure mass flow controllers, as an efficient and reliable flow measurement and regulation tool, have become an important part of the flow control system.

[0003] A differential pressure mass flow controller (differential pressure flowmeter) is a device that uses the pressure difference generated when a fluid flows through a pipeline to measure flow. That is, when a gas flows through a throttling device equipped with an orifice plate, the gas flow rate increases due to the circular hole in the center of the orifice plate (equivalent to a narrow channel). The increase in flow rate will cause the kinetic energy of the gas in the pipeline to increase. According to Bernoulli's principle, the increase in the kinetic energy of the gas causes the static pressure to decrease. At this time, the static pressure difference before and after the orifice plate becomes the key to flow measurement. By measuring the differential pressure before and after the orifice plate in the pipeline, combined with the known flow-differential pressure relationship formula, the gas flow rate can be calculated.

[0004] Although differential pressure flow controllers are widely used, they also have some limitations in practical use. On the one hand, the gas flow is not always completely in a laminar state. In practical applications, gas flow is often turbulent or transitional flow, especially under high flow rates and low pressure differences. The non-ideal, turbulent and non-stable flow of gas will lead to measurement errors and affect the relationship between differential pressure and flow. On the other hand, the pressure loss caused by the throttling effect of the orifice plate not only affects the efficiency of fluid flow, but may also affect the energy efficiency of the entire system, especially when long-distance gas transportation is required, the cumulative effect of pressure loss is more obvious. Therefore, differential pressure flow meters have the problems of low measurement accuracy and large pressure loss.

[0005] In the prior art, a Chinese patent document with publication number CN 111272236A discloses a method for calculating the gas flow rate of a gas laminar flow meter, including the steps of selecting a point with a pressure value of pa as an auxiliary point a, calibrating the instrument coefficient K by the initial volume flow qa1 of the auxiliary point a, and calculating the actual gas flow rate using the calibrated instrument coefficient K. This scheme assumes that a linear relationship is always maintained between the volume flow rate and the differential pressure at the auxiliary point a, which makes it less adaptable when facing complex gas flows, temperature fluctuations or changes in gas types, and reduces the accuracy within a wider flow range. Summary of the invention

[0006] The embodiments described herein provide a flow control method and a flow control device based on a differential pressure flow meter.

[0007] According to the first aspect of the present disclosure, a flow control method based on a differential pressure flowmeter is provided, comprising: connecting the differential pressure flowmeter in series with the gas path of a standard flow device, a pressure sensor is provided upstream of the laminar flow element of the differential pressure flowmeter for measuring the upstream pressure value, a differential pressure sensor and a temperature sensor are provided inside the laminar flow element for measuring the differential pressure value between the upstream and downstream of the laminar flow element and the thermodynamic temperature value of the gas, respectively; controlling the differential pressure between the upstream and downstream of the laminar flow element to reach a plurality of different differential pressure values, obtaining a plurality of groups of corresponding flow values ​​and viscosity coefficients of the differential pressure flowmeter based on the calibration value of the standard flow device and the measured values ​​of the pressure sensor, the differential pressure sensor and the temperature sensor, respectively; fitting the instrument coefficients of the ratios of the flow values ​​of the plurality of groups of differential pressure flowmeters to the corresponding differential pressure values ​​and viscosity coefficients based on the least squares method; and obtaining the target flow, calculating the required control differential pressure value based on the instrument coefficient and the viscosity coefficient at the current temperature, so as to achieve the target flow by controlling the differential pressure value.

[0008] In some embodiments of the present disclosure, the standard measuring device is used to provide a calibrated flow value, a calibrated temperature value, and a calibrated pressure value, and the laminar flow element makes the Reynolds number of the fluid flowing through the differential pressure flowmeter less than 2000.

[0009] In some embodiments of the present disclosure, multiple groups of different differential pressure values ​​and their corresponding flow values ​​and viscosity coefficients of the differential pressure flow meter are obtained by the following steps:

[0010] Step 1, by controlling the proportional valve disposed upstream of the laminar flow element, the differential pressure value between the upstream and downstream of the laminar flow element is adjusted to a specified differential pressure value ΔP, the thermodynamic temperature T1 and the upstream pressure value P1 of the gas are measured at this time, and the volume flow rate Q2, the internal thermodynamic temperature T2 and the pressure value P2 of the standard flow device are recorded;

[0011] Step 2: Calculate the volume flow rate Q1 of the differential pressure flowmeter based on the ideal gas state equation:

[0012]

[0013] Step 3, look up the table to obtain the viscosity coefficient of the gas corresponding to the current temperature T1; and

[0014] Repeat steps 1 to 3, and adjust the differential pressure values ​​upstream and downstream of the laminar flow element to a plurality of specified different differential pressure values ​​by controlling the proportional valve, so as to obtain a plurality of different sets of differential pressure values ​​and their corresponding flow values ​​and viscosity coefficients of the differential pressure flowmeter.

[0015] In some embodiments of the present disclosure, the differential pressure and flow are fitted for different flow ranges to find the minimum flow range that meets the linear relationship; the actual flow usage range of the differential pressure flowmeter is segmented according to the minimum flow range, and the differential pressure and flow in each segment are in a linear relationship; for each flow segment, the differential pressure and flow fitting results are fitted using the least squares method to calculate the instrument coefficient of the flow segment.

[0016] In some embodiments of the present disclosure, the target flow rate under working conditions is converted to the target flow rate under standard conditions based on the following formula:

[0017]

[0018] Wherein, Q' is the target flow rate under standard conditions, Q1 is the target flow rate under working conditions, P1 and T1 are the pressure and temperature under standard conditions, P2 and T2 are the pressure and temperature measured by the sensor under the current working conditions, Z2 is the compression factor under the current working conditions, and Z1 is the compression factor under standard conditions; select the corresponding instrument coefficient according to the flow segment where the target flow rate under standard conditions is located; based on the selected instrument coefficient, use the following formula to calculate the differential pressure value corresponding to the target flow rate under standard conditions:

[0019]

[0020] Wherein, η is the viscosity coefficient at the current temperature, Q' is the target flow rate under standard conditions, ΔP is the required control differential pressure; and the valve opening of the proportional valve is controlled based on the control differential pressure so that the flow rate of the differential pressure flowmeter reaches the target flow rate under standard conditions.

[0021] According to the second aspect of the present disclosure, a flow control device based on a differential pressure flowmeter is provided, including a differential pressure flowmeter, an air pipeline, a standard flow device and a computing device, wherein the differential pressure flowmeter includes a laminar flow element and a pressure sensor, a differential pressure sensor, a temperature sensor and a proportional valve arranged on the laminar flow element, and the computing device is electrically connected to the pressure sensor, the differential pressure sensor, the temperature sensor, the proportional valve and the standard flow device, respectively, and is suitable for receiving pressure values, differential pressure values ​​and temperature values ​​measured by the sensors and calibrated flow values, calibrated temperature values ​​and calibrated pressure values ​​of the standard flow device, and based on the flow control method based on the differential pressure flowmeter as the first aspect of the present invention, a required control differential pressure value is calculated, and the valve opening of the proportional valve is controlled according to the required control differential pressure value, so that the differential pressure flowmeter reaches the required target flow.

[0022] In some embodiments of the present disclosure, the differential pressure flow meter and the standard flow device are connected in series through an air pipeline, and the standard measuring device is used to provide a calibrated flow value, a calibrated temperature value, and a calibrated pressure value.

[0023] In some embodiments of the present disclosure, a throttling device is built into the laminar flow element, and the Reynolds number of the fluid flowing through the differential pressure flowmeter is less than 2000.

[0024] In some embodiments of the present disclosure, a pressure sensor is arranged upstream of a laminar flow element of a differential pressure flowmeter to measure the upstream pressure value of the laminar flow element. The differential pressure sensor and the temperature sensor are arranged inside the laminar flow element to measure the differential pressure value between the upstream and downstream of the laminar flow element and the thermodynamic temperature value of the gas, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure, but are not intended to limit the present disclosure, wherein:

[0026] Figure 1 A schematic structural diagram of a flow control device based on a differential pressure flow meter according to an embodiment of the present disclosure is shown;

[0027] Figure 2 A flow chart showing a flow control method 200 based on a differential pressure flow meter according to an embodiment of the present disclosure is shown;

[0028] Figure 3 is a schematic block diagram of a computing device 300 according to an embodiment of the present disclosure.

[0029] It should be noted that the elements in the drawings are schematic and not drawn to scale. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0031] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person skilled in the art to which the subject matter of the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal form unless otherwise explicitly defined herein. As used herein, a statement that two or more parts are "connected" or "coupled" together shall mean that the parts are joined together directly or through one or more intermediate components.

[0032] Those skilled in the art should understand that a differential pressure flowmeter indirectly infers flow rate by measuring the differential pressure generated by the local flow velocity change when the fluid flows through a section of a pipe. The goal of the disclosed embodiment is to accurately control the flow rate by controlling the differential pressure value of the differential pressure flowmeter, especially when it is necessary to consider the relationship between the viscosity of the gas and the flow rate, to fit the instrument coefficient by the least squares method, and then use the instrument coefficient to achieve the purpose of accurately controlling the flow rate by controlling the differential pressure.

[0033] The embodiments of the present disclosure provide a flow control method and a flow control device based on a differential pressure flow meter. Figure 1 The structure diagram of the flow control device based on the differential pressure flow meter according to the embodiment of the present disclosure is shown. Figure 1 In the example, the flow control device includes a differential pressure flow meter, an air pipeline (including an air inlet and an air outlet), a standard flow device and a computing device. The differential pressure flow meter includes a laminar flow element and a pressure sensor, a differential pressure sensor, a temperature sensor and a proportional valve arranged on the laminar flow element. The computing device is electrically connected to the pressure sensor, the differential pressure sensor, the temperature sensor, the proportional valve and the standard flow device respectively. The differential pressure flow meter and the standard flow device are connected in series through the air pipeline.

[0034] exist Figure 1 In the example, a proportional valve is provided between the air inlet and the upstream of the laminar flow element, and the differential pressure value between the upstream and downstream of the laminar flow element can be continuously controlled by inputting an electrical signal. The laminar flow element has a built-in throttling device. The premise of the flow accuracy control based on the Poiseuille equation in this scheme is that the fluid is always in a laminar state in the device. In this case, the Reynolds number of the fluid flowing through the laminar flow element of the differential pressure flowmeter is less than 2000. Avoid using structures such as sharp turns, contractions, and expansions in laminar flow elements, and use a progressive expansion and contraction design.

[0035] The pressure sensor is arranged upstream of the laminar flow element of the differential pressure flowmeter to measure the upstream pressure value. The differential pressure sensor and the temperature sensor are arranged inside the laminar flow element to measure the differential pressure value between the upstream and downstream of the laminar flow element and the thermodynamic temperature value of the gas respectively.

[0036] The computing device can receive the pressure value, differential pressure value and temperature value measured by the sensor and the calibrated flow value, calibrated temperature value and calibrated pressure value of the standard flow device, and calculate the required control differential pressure value based on the flow control method based on the differential pressure flowmeter provided in the embodiment of the present disclosure, so as to control the valve opening of the proportional valve according to the control differential pressure value, so that the differential pressure flowmeter reaches the required target flow.

[0037] Figure 2 FIG. 2 is a flow chart showing a flow control method 200 based on a differential pressure flow meter according to an embodiment of the present disclosure. Figure 2As shown, in box S210, the differential pressure flowmeter is connected in series with the gas circuit of the standard flow device, and a pressure sensor is arranged upstream of the laminar flow element of the differential pressure flowmeter for measuring the upstream pressure value. The differential pressure sensor and the temperature sensor are arranged inside the laminar flow element for measuring the differential pressure value between the upstream and downstream of the laminar flow element and the thermodynamic temperature value of the gas, respectively.

[0038] Since there is a known mathematical relationship between the differential pressure and flow rate of a differential pressure flowmeter, the flow rate of the gas can be calculated by measuring the differential pressure before and after the orifice plate in the pipeline and combining it with the known flow-differential pressure relationship formula. The disclosed embodiment takes into account that during the processing of laminar flow elements, due to manufacturing tolerances and dimensional errors, there may be a deviation between the flow rate and the expected design value. This deviation manifests itself as the relationship between the flow rate and the control parameters is no longer completely linear. The key to this solution is to fit the instrument coefficient through multiple sets of experimental data, and then use it to accurately control the flow rate by controlling the differential pressure.

[0039] In one embodiment of the present disclosure, the differential pressure flowmeter is connected in series with a standard flow device gas circuit. The standard flow device is a device with a known flow rate, which provides a calibrated flow value. By comparing with the standard flow device, the relationship between the actual flow rate and the theoretical calculated flow rate can be obtained, and the control strategy can be adjusted.

[0040] Combination Figure 1 As shown, a pressure sensor can be set upstream of the laminar flow element of the differential pressure flowmeter, and a differential pressure sensor and a temperature sensor can be set inside the laminar flow element. The differential pressure value between the upstream and downstream of the laminar flow element is measured by the differential pressure sensor, the upstream pressure value is measured by the pressure sensor, and the thermodynamic temperature of the gas is measured by the temperature sensor. The same standard flow device is also equipped with a pressure sensor and a temperature sensor. The internal structure of the laminar flow element makes the Reynolds number of the fluid flowing through the differential pressure flowmeter less than 2000, that is, the fluid is always in a laminar state in the flow control device.

[0041] exist Figure 2 In box S220, the differential pressure between the upstream and downstream of the laminar flow element is controlled to reach multiple different differential pressure values, and multiple groups of corresponding flow values ​​and viscosity coefficients of differential pressure flow meters are obtained based on the calibration values ​​of the standard flow device and the measured values ​​of the pressure sensor, differential pressure sensor and temperature sensor.

[0042] In the embodiments of the present disclosure, the flow values ​​of the differential pressure flow meter corresponding to different differential pressure values ​​and the viscosity coefficient at the current temperature can be obtained respectively by the following steps:

[0043] Step 1, by controlling the proportional valve disposed upstream of the laminar flow element, the differential pressure value between the upstream and downstream of the laminar flow element is adjusted to a specified differential pressure value ΔP, the thermodynamic temperature T1 and the upstream pressure value P1 of the gas are measured at this time, and the volume flow rate Q2, the internal thermodynamic temperature T2 and the pressure value P2 of the standard flow device are recorded;

[0044] Step 2: Calculate the volume flow rate Q1 of the differential pressure flowmeter based on the ideal gas state equation:

[0045]

[0046] Step 3, look up the table to obtain the viscosity coefficient of the gas corresponding to the current temperature T1; and

[0047] Repeat steps 1 to 3, and adjust the differential pressure values ​​upstream and downstream of the laminar flow element to a plurality of specified different differential pressure values ​​by controlling the proportional valve, so as to obtain a plurality of different sets of differential pressure values ​​and their corresponding flow values ​​and viscosity coefficients of the differential pressure flowmeter.

[0048] Specifically, by controlling the proportional valve disposed upstream of the laminar flow element, the differential pressure between the upstream and downstream of the laminar flow element is adjusted to a specified first differential pressure value ΔP1, and the thermodynamic temperature T of the gas at this time is measured. 11 and upstream pressure value P 11 , record the volume flow rate Q of the standard flow device 21 , internal thermodynamic reference temperature T 21 and reference pressure value P 21 ;

[0049] Calculate the volume flow rate Q of the differential pressure flowmeter based on the ideal gas state equation 11 :

[0050]

[0051] Look up the table to get the current temperature T 11 The corresponding gas viscosity coefficient η1.

[0052] By controlling the proportional valve set upstream of the laminar flow element, the differential pressure value upstream and downstream of the laminar flow element is adjusted to the specified second differential pressure value ΔP2, and the thermodynamic temperature T of the gas at this time is measured. 12 and upstream pressure value P 12 , record the volume flow rate Q of the standard flow device 22 , internal thermodynamic reference temperature T 22 and reference pressure value P 22 ;

[0053] Calculate the volume flow rate Q of the differential pressure flowmeter based on the ideal gas state equation 12 :

[0054]

[0055] Look up the table to get the current temperature T 12 The corresponding gas viscosity coefficient η2.

[0056] By analogy, multiple groups of different differential pressure values ​​and their corresponding flow values ​​and viscosity coefficients of the differential pressure flowmeter are obtained. For example, n groups of fitting data are obtained:

[0057] [(ΔP1, T 11 ,η1),(ΔP2,Q 12 ,η2)......(ΔP n , Q 1n , η n )].

[0058] In block S230, meter coefficients are fitted based on the least square method for the ratios of flow values ​​of multiple groups of differential pressure flow meters to the corresponding differential pressure values ​​and viscosity coefficients.

[0059] Calculate the quotient ΔP / η of each set of differential pressure values ​​and the viscosity coefficient, and use the least squares method to fit the instrument coefficient K, so that the relationship between volume flow and differential pressure can be accurately obtained. Since the relationship between differential pressure and flow data may no longer be linear in a wider flow range, the piecewise least squares method can be used for fitting. The specific steps are as follows:

[0060] Fit the differential pressure and flow rate for different flow ranges to find the minimum flow range that meets the linear relationship and ensure that the relationship between the differential pressure and flow rate in each flow section is linear.

[0061] The actual flow range of the differential pressure flowmeter is divided into segments according to the minimum flow range, and the differential pressure and flow in each segment are linearly related. For each flow segment, the differential pressure and flow fitting results are fitted using the least squares method to calculate the instrument coefficient of the flow segment. Each flow segment will have a corresponding instrument coefficient.

[0062] Finally, in block S240, the target flow rate is obtained, and the required control differential pressure value is calculated based on the instrument coefficient and the viscosity coefficient at the current temperature, so as to achieve the target flow rate by controlling the differential pressure value.

[0063] The actual target flow rate can be converted into the corresponding differential pressure through the obtained instrument coefficient, so as to achieve accurate control of the flow rate. When the target flow rate needs to be controlled, the corresponding instrument coefficient is selected according to the flow segment where the target flow rate is located.

[0064] However, the actual gas state often deviates from the ideal gas state. A compression factor can be introduced for correction. After the correction, when the flow is subsequently controlled at different pressures and temperatures, the flow to be controlled is converted to standard conditions for control.

[0065] In the embodiment of the present disclosure, after the instrument coefficient is obtained, when it is applied to the actual gas, the state equation is corrected by the Z factor. After the correction, when the flow is subsequently controlled at different pressures and temperatures, the flow to be controlled is converted to the standard condition for control. The target flow under the working condition can be converted to the target flow under the standard condition and calculated by the following formula:

[0066]

[0067] Among them, Q1 is the volume flow rate under standard conditions, Q2 is the volume flow rate calculated by the instrument coefficient under working conditions, P1 and T1 are the pressure and temperature under standard conditions, P2 and T2 are the pressure and temperature measured by the sensor under the current working conditions, Z2 is the compression factor under the current working conditions, and Z1 is the compression factor under standard conditions.

[0068] Then, select the corresponding instrument coefficient according to the flow segment where the standard target flow is located. Based on the selected instrument coefficient, use the following formula to calculate the differential pressure value corresponding to the standard target flow:

[0069]

[0070] Where η is the viscosity coefficient at the current temperature obtained from the table, Q' is the target flow rate under standard conditions, ΔP d is the required control differential pressure value.

[0071] Finally, the valve opening of the proportional valve is controlled based on the control differential pressure value so that the flow rate of the differential pressure flowmeter reaches the target flow rate under standard conditions.

[0072] An embodiment of the present disclosure also provides a computing device. Figure 3 is a schematic block diagram of a computing device 300 according to an embodiment of the present disclosure. Figure 3 As shown, the computing device 300 may include a processor 310 and a memory 320 storing a computer program. When the computer program is executed by the processor 310, the computing device 300 may perform the following operations: Figure 2 The steps of the flow control method 200 based on the differential pressure flow meter are shown.

[0073] The computing device 300 can control the differential pressure between the upstream and downstream of the laminar flow element to reach multiple different differential pressure values, and obtain multiple groups of corresponding flow values ​​and viscosity coefficients of differential pressure flow meters based on the calibration value of the standard flow device and the measurement values ​​of the pressure sensor, the differential pressure sensor and the temperature sensor; fit the instrument coefficient based on the least squares method for the ratio of the flow values ​​of multiple groups of differential pressure flow meters to the corresponding differential pressure values ​​and viscosity coefficients; and obtain the target flow, and calculate the required control differential pressure value based on the instrument coefficient and the viscosity coefficient at the current temperature, so as to achieve the target flow by controlling the differential pressure value.

[0074] In some embodiments of the present disclosure, the computing device 300 may calculate the flow value of the differential pressure flow meter corresponding to different differential pressure values ​​and the viscosity coefficient at the current temperature through the following steps:

[0075] Step 1, by controlling the proportional valve disposed upstream of the laminar flow element, the differential pressure value between the upstream and downstream of the laminar flow element is adjusted to a specified differential pressure value ΔP, the thermodynamic temperature T1 and the upstream pressure value P1 of the gas are measured at this time, and the volume flow rate Q2, the internal thermodynamic temperature T2 and the pressure value P2 of the standard flow device are recorded;

[0076] Step 2: Calculate the volume flow rate Q1 of the differential pressure flowmeter based on the ideal gas state equation:

[0077]

[0078] Step 3, look up the table to obtain the viscosity coefficient of the gas corresponding to the current temperature T1; and

[0079] Repeat steps 1 to 3, and adjust the differential pressure values ​​upstream and downstream of the laminar flow element to multiple specified different differential pressure values ​​by controlling the proportional valve, and calculate multiple groups of different differential pressure values ​​and their corresponding flow values ​​of the differential pressure flowmeter and the viscosity coefficient at the current temperature.

[0080] In some embodiments of the present disclosure, the computing device 300 can fit the differential pressure and flow rate for different flow ranges to find the minimum flow range that conforms to the linear relationship; divide the actual flow usage range of the differential pressure flowmeter into segments according to the minimum flow range, and the differential pressure and flow rate in each segment are in a linear relationship; and for each flow segment, use the least squares method to fit the differential pressure and flow rate to calculate the instrument coefficient of the flow segment.

[0081] In some embodiments of the present disclosure, the computing device 300 may convert the target flow rate under standard conditions into:

[0082]

[0083] Wherein, Q' is the target flow rate under standard conditions, Q1 is the target flow rate under working conditions, P1 and T1 are the pressure and temperature under standard conditions, respectively, O2 and T2 are the pressure and temperature measured by the sensor under the current working conditions, Z2 is the compression factor under the current working conditions, and Z1 is the compression factor under standard conditions.

[0084] According to the flow segment where the standard target flow is located, select the corresponding instrument coefficient; based on the selected instrument coefficient, use the following formula to calculate the differential pressure value corresponding to the standard target flow:

[0085]

[0086] Where η is the viscosity coefficient at the current temperature, Q' is the target flow rate under standard conditions, ΔP d is the required control differential pressure value; and based on the control differential pressure value, the valve opening of the proportional valve is controlled so that the flow rate of the differential pressure flowmeter reaches the target flow rate under standard conditions.

[0087] In an embodiment of the present disclosure, the processor 310 may be, for example, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a processor based on a multi-core processor architecture, etc. The memory 320 may be any type of memory implemented using data storage technology, including but not limited to random access memory, read-only memory, semiconductor-based memory, flash memory, disk storage, etc.

[0088] In addition, in the embodiment of the present disclosure, the computing device 300 may also include an input device 330 for inputting measurement values ​​and calibration values. In addition, the computing device 300 may also include an output device 340, such as a display, for outputting a control differential pressure value.

[0089] In other embodiments of the present disclosure, a computer-readable storage medium storing a computer program is further provided, wherein the computer program can achieve the following when executed by a processor: Figure 2 The steps of method 200 are shown.

[0090] In summary, according to the flow control method and flow control device based on the differential pressure flowmeter of the embodiment of the present disclosure, a more accurate instrument coefficient can be obtained by fitting the relationship between flow, differential pressure and viscosity coefficient by the least squares method. This fitting method not only improves the calculation accuracy of the flowmeter, but also can be optimized according to multiple sets of different measurement data, so that the differential pressure flowmeter can obtain higher measurement accuracy under various working conditions. This adaptive control scheme based on real-time data feedback is more flexible and accurate than traditional single-point calibration or control methods based on fixed formulas, and can provide better performance in complex operating environments.

[0091] Unless the context clearly indicates otherwise, the singular form of the words used herein and in the appended claims includes the plural and vice versa. Thus, when referring to the singular, the plural form of the corresponding term is generally included. Similarly, the words "comprise" and "include" are to be interpreted as inclusive rather than exclusive. Likewise, the terms "include" and "or" should be interpreted as inclusive unless such interpretation is expressly prohibited herein. Where the term "example" is used herein, particularly when it is located after a group of terms, the "example" is merely exemplary and illustrative and should not be considered exclusive or comprehensive.

[0092] Further aspects and scopes of adaptability become apparent from the description provided herein. It should be understood that various aspects of the present application can be implemented individually or in combination with one or more other aspects. It should also be understood that the description and specific embodiments herein are intended for purposes of illustration only and are not intended to limit the scope of the present application.

[0093] Several embodiments of the present disclosure are described in detail above, but it is obvious that those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. The protection scope of the present disclosure is defined by the attached claims.

Claims

1. A flow control method based on a differential pressure flow meter, characterized in that: include: A differential pressure flow meter is connected in series with the gas path of a standard flow device, wherein a pressure sensor is provided upstream of the laminar flow element of the differential pressure flow meter to measure the upstream pressure value, and a differential pressure sensor and a temperature sensor are provided inside the laminar flow element to measure the differential pressure value between the upstream and downstream of the laminar flow element and the thermodynamic temperature value of the gas, respectively; Controlling the differential pressure between the upstream and downstream of the laminar flow element to reach a plurality of different differential pressure values, and obtaining a plurality of corresponding sets of flow values ​​and viscosity coefficients of differential pressure flow meters based on the calibration value of the standard flow device and the measured values ​​of the pressure sensor, the differential pressure sensor and the temperature sensor; Based on the least square method, the instrument coefficients are fitted from the flow values ​​of multiple groups of differential pressure flow meters to the corresponding differential pressure values ​​and the ratio of the viscosity coefficient. as well as The target flow rate is obtained, and the required control differential pressure value is calculated based on the instrument coefficient and the viscosity coefficient at the current temperature, so as to achieve the target flow rate by controlling the differential pressure value.

2. The flow control method based on the differential pressure flowmeter according to claim 1, characterized in that: The standard measuring device is used to provide a calibrated flow value, a calibrated temperature value and a calibrated pressure value, and the laminar flow element makes the Reynolds number of the fluid flowing through the differential pressure flowmeter less than 2000.

3. The flow control method based on the differential pressure flowmeter according to claim 1, characterized in that: The differential pressure between the upstream and downstream of the laminar flow element is controlled to reach a plurality of different differential pressure values, and a plurality of corresponding flow values ​​and viscosity coefficients of differential pressure flow meters are obtained based on the calibration value of the standard flow device and the measured values ​​of the pressure sensor, the differential pressure sensor and the temperature sensor respectively, by the following steps: Step 1, by controlling the proportional valve disposed upstream of the laminar flow element, the differential pressure value between the upstream and downstream of the laminar flow element is adjusted to a specified differential pressure value ΔP, the thermodynamic temperature T1 and the upstream pressure value P1 of the gas at this time are measured, and the volume flow rate Q2, the internal thermodynamic temperature T2 and the pressure value P2 of the standard flow device are recorded; Step 2: Calculate the volume flow Q1 of the differential pressure flowmeter based on the ideal gas state equation: Step 3, look up the table to obtain the viscosity coefficient of the gas corresponding to the current temperature T1; as well as Repeat steps 1 to 3, and adjust the differential pressure values ​​upstream and downstream of the laminar flow element to multiple specified different differential pressure values ​​by controlling the proportional valve, so as to obtain multiple groups of different differential pressure values ​​and their corresponding flow values ​​and viscosity coefficients of the differential pressure flowmeter.

4. The flow control method based on the differential pressure flowmeter according to claim 3 is characterized in that: The instrument coefficients are fitted based on the least square method to the ratios of flow values ​​of multiple groups of differential pressure flow meters to corresponding differential pressure values ​​and viscosity coefficients, including: Fit the differential pressure and flow rate for different flow ranges to find the minimum flow range that meets the linear relationship; The actual flow usage range of the differential pressure flowmeter is divided into sections according to the minimum flow range, and the differential pressure and flow in each section are in a linear relationship; and For each flow segment, the differential pressure and flow fitting results are fitted using the least squares method to calculate the instrument coefficient of the flow segment.

5. The flow control method based on the differential pressure flowmeter according to claim 4, characterized in that: The step of obtaining the target flow rate and calculating the required control differential pressure value based on the instrument coefficient and the viscosity coefficient at the current temperature so as to achieve the target flow rate by controlling the differential pressure value includes: Convert the target flow rate under working conditions into the target flow rate under standard conditions; According to the flow segment where the target flow under the standard condition is located, select the corresponding instrument coefficient; Based on the selected instrument coefficient, the differential pressure value corresponding to the target flow under the standard condition is calculated using the following formula: Where η is the viscosity coefficient at the current temperature, Q' is the target flow rate under standard conditions, ΔP d is the desired control differential pressure value; and The valve opening of the proportional valve is controlled based on the control differential pressure value so that the flow rate of the differential pressure flowmeter reaches the target flow rate under standard conditions.

6. The flow control method based on the differential pressure flowmeter according to claim 5, characterized in that: The target flow rate under working conditions is converted to the target flow rate under standard conditions based on the following formula: Wherein, Q' is the target flow rate under standard conditions, Q1 is the target flow rate under working conditions, P1 and T1 are the pressure and temperature under standard conditions, P2 and T2 are the pressure and temperature measured by the sensor under the current working conditions, Z2 is the compression factor under the current working conditions, and Z1 is the compression factor under standard conditions.

7. A flow control device based on a differential pressure flow meter, characterized in that: It includes a differential pressure flowmeter, an air pipeline, a standard flow device and a computing device; the differential pressure flowmeter includes a laminar flow element and a pressure sensor, a differential pressure sensor, a temperature sensor and a proportional valve arranged on the laminar flow element, and the computing device is electrically connected to the pressure sensor, the differential pressure sensor, the temperature sensor, the proportional valve and the standard flow device, respectively, and is suitable for receiving the pressure value, differential pressure value and temperature value measured by the sensor and the calibrated flow value, calibrated temperature value and calibrated pressure value of the standard flow device, and calculates the required control differential pressure value based on the flow control method based on the differential pressure flowmeter as described in any one of claims 1-6, so as to control the valve opening of the proportional valve according to the control differential pressure value, so that the differential pressure flowmeter reaches the required target flow.

8. The flow control device based on the differential pressure flow meter according to claim 7, characterized in that: The differential pressure flow meter and the standard flow device are connected in series via the gas pipeline, and the standard measuring device is used to provide a calibrated flow value, a calibrated temperature value and a calibrated pressure value.

9. The flow control device based on the differential pressure flow meter according to claim 7, characterized in that: The laminar flow element has a built-in throttling device, and the Reynolds number of the fluid flowing through the differential pressure flowmeter is less than 2000.

10. The flow control device based on the differential pressure flow meter according to claim 7, characterized in that: The pressure sensor is arranged upstream of the laminar flow element for measuring the upstream pressure value of the laminar flow element. The differential pressure sensor and the temperature sensor are arranged inside the laminar flow element for measuring the differential pressure value between the upstream and downstream of the laminar flow element and the thermodynamic temperature value of the gas respectively.

Images