Method and apparatus for determining the effect of piston flow meter inclination angle on flow measurement

Abstract

The present invention provides a method and device for determining the influence of the inclination angle of a piston flowmeter on flow measurement, which comprises a gas source and two branches for outputting two airflows; two mass flow controllers are respectively arranged on the two branches for outputting two stable airflows; two gas path control valves A and B are respectively arranged on the two branches for controlling the on and off of the airflows in the two branches; a piston flowmeter is configured, and the two branches are sent into the piston flowmeter after converging at the ends; an angle adjustment mechanism and an angle measurement device are configured, which are respectively used to adjust the inclination angle of the piston flowmeter and measure the inclination angle of the piston flowmeter, and then the influence of the inclination angle on the flow measurement of the piston flowmeter is statistically analyzed with the help of an algorithm.

Description

Technical Field

[0001] The present invention relates to the field of flow meter calibration, and in particular to a method for determining the influence of the inclination angle of a piston flow meter on flow measurement, and a corresponding device. Background Art

[0002] The working principle of the piston flowmeter is: the gas flows into the downstream of the piston cylinder through the inlet, and the bypass valve is in a closed state. The gas pressure under the piston rises sharply due to the influence of the flow-blocking graphite piston, thereby pushing the piston upward. When the pressure generated by the gas under the piston reaches a balance with the gravity and friction of the piston, the piston begins to rise at a uniform speed until it enters the measuring section. After the measurement is completed, the bypass valve is opened to release the pressure, and the piston returns to the bottom position under the action of gravity.

[0003] The gap-sealed piston flow meter is one type of piston flow meter.

[0004] It is a form of sealing that uses the small radial gap between the piston and the cylinder body and a certain length of the gap in the axial direction. The gap-sealed piston structure is the main component of the flow measurement unit. It is mainly composed of a piston cylinder, a piston and a photoelectric detector. The piston is made of a material with a low temperature expansion coefficient and a low friction coefficient. The gap-sealed piston structure is different from the common mercury seal, rubber ring seal and other methods. It always has a certain amount of leakage.

[0005] The leakage amount is related to many factors, and the tilt of the piston is one of the influencing factors. In order to improve the accuracy of the gap seal piston flowmeter, it is necessary to provide a method to determine the influence of the tilt angle of the piston flowmeter on the measurement results of the gap piston flowmeter. Summary of the invention

[0006] The purpose of the present invention is to address the deficiencies of the prior art and thereby provide a method and device for determining the influence of the inclination angle of a piston flowmeter on flow measurement, which can accurately reflect the influence of the inclination angle of the piston flowmeter on the measurement results of the gap piston flowmeter.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: a method for determining the influence of the inclination angle of a piston flowmeter on flow measurement, comprising the following steps:

[0008] Configure one gas source and two branches to output two gas flows;

[0009] Two mass flow controllers are respectively arranged on two branches to output two stable airflows;

[0010] Two gas circuit control valves A and B are respectively arranged on the two branches to control the on and off of the airflow in the two branches;

[0011] A piston flow meter is configured, and the two branches converge at the end and are sent to the piston flow meter;

[0012] An angle adjustment mechanism and an angle measuring device are configured to adjust the inclination angle of the piston flowmeter and measure the inclination angle of the piston flowmeter respectively;

[0013] Set up the calculation model:

[0014] q m =ρ(P a ,T)q V (1)

[0015]

[0016]

[0017] q*m1+m2+qmL=q*m1+qmL+q*m2+qmL

[0018] qmL=q*m1+m2-(q*m1+q*m2) (4)

[0019] In formulas (1)-(4), q m is the mass flow rate, P a is atmospheric pressure, T is the gas temperature inside the piston cylinder, ρ(P a ,T) is the atmospheric pressure P a , gas density at temperature T, q V is the volume flow rate, t is the measurement time interval, V is the volume traveled by the piston in the time interval t, q L is the leakage volume flow rate, q mL is the leakage mass flow rate, and the ones with * are the uncorrected readings of the piston flowmeter;

[0020] Calculation process:

[0021] Step (a) The inclination angle of the piston flowmeter is 0,

[0022] Among them, open valve A, close valve B, and get q*m1; open valve A and valve B, and get q*m1+m2; open valve B, close valve A, and get q*m2; qmL1 can be calculated from formula (4), and qL1 can be calculated from formula (3);

[0023] Multiple qmL can be obtained by cycling through the following measurement sequence:

[0024] The measurement cycle sequence is:

[0025] The first group: q*m1, q*m1+m2, q*m2

[0026] The second group: q*m1+m2, q*m2, q*m1

[0027] The third group: q*m2, q*m1, q*m1+m2

[0028] ……, measure N times in a cycle;

[0029] The final leakage flow is:

[0030] Step (b) tilting at a certain angle α;

[0031] The measurement sequence is the same as that in step (a);

[0032] Step (c) Measure the leakage flow rate q at multiple tilt angles L , we can get the influence of the inclination angle on the flow measurement of the piston flowmeter.

[0033] Based on the above, in step (a), the piston flowmeter is arranged vertically.

[0034] Based on the above, in step (c), the leakage flow rates measured at different angles are compared with the leakage flow rate at 0° to generate a distribution diagram of the tilt angle and the leakage flow rate.

[0035] Based on the above, the measurement environment is a constant temperature and humidity environment.

[0036] Based on the above, it includes a constant temperature and humidity chamber, and the branch, mass flow controller, gas circuit control valve, piston flowmeter, angle adjustment mechanism and angle measurement device are all located in the constant temperature and humidity chamber.

[0037] A device for determining the influence of the inclination angle of a piston flowmeter on flow measurement, comprising an intake pipeline, a first branch, a second branch, a first mass flow controller, a second mass flow controller, a first gas path control valve, a second gas path control valve, a converging gas path, a piston flowmeter, an angle adjustment mechanism and an angle measuring device, wherein the intake pipeline connects the first branch and the second branch, the first mass flow controller and the first gas path control valve are installed in series on the first branch, the second mass flow controller and the second gas path control valve are installed in series on the second branch, the first branch and the second branch are connected to the converging gas path, the converging gas path is connected to the piston flowmeter, the angle adjustment mechanism is used to adjust the angle of the piston flowmeter, and the angle measuring device is used to detect the inclination angle of the piston flowmeter.

[0038] Based on the above, it also includes a constant temperature and humidity chamber, in which the air intake pipeline, the first branch, the second branch, the first mass flow controller, the second mass flow controller, the first gas path control valve, the second gas path control valve, the converging gas path, the piston flowmeter, the angle adjustment mechanism and the angle measurement device are all arranged.

[0039] Based on the above, the angle adjustment mechanism includes a base and lifting rods arranged at four corners of the base, the bottom ends of the lifting rods are fixed to the base, and the top ends of the four lifting rods are respectively hinged to the four bottom feet of the piston flowmeter.

[0040] Based on the above, the angle measuring device includes an inclination sensor or an angle measuring instrument provided for the piston flow meter.

[0041] Compared with the prior art, the present invention has outstanding substantial features and significant progress. Specifically, the present invention designs an angle adjustment mechanism that can freely adjust the inclination angle, which is used to adjust the inclination angle of the piston flowmeter. At the same time, a corresponding angle measuring device is provided to detect the inclination angle of the piston flowmeter in real time, and then the piston flowmeter is supplied with airflow separately or simultaneously through two stable air paths to calculate the leakage flow. By designing a corresponding algorithm, multi-group and multi-cycle statistical measurements are performed, and finally the leakage flow at different angles can be obtained, and then the influence of the inclination angle on the flow measured by the piston flowmeter can be obtained.

[0042] Furthermore, the entire device is designed in a constant temperature and humidity environment to avoid the influence of other environmental parameters.

[0043] Furthermore, the angle adjustment device uses four lifting rods to support the four corners of the piston flowmeter, and the direction and angle of the inclination can be accurately controlled and achieved, which increases the flexibility of measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural principle diagram of the method for determining the influence of the inclination angle of the piston flowmeter on the flow measurement in the present invention.

[0045] In the figure: 1. Inlet pipeline; 2. First branch; 3. Second branch; 4. First mass flow controller; 5. Second mass flow controller; 6. First gas path control valve; 7. Second gas path control valve; 8. Converging gas path; 9. Piston flowmeter; 10. Angle adjustment mechanism; 10-1. Base; 10-2. Lifting rod; 11. Angle measuring device; 12. Constant temperature and humidity chamber. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0047] like Figure 1As shown, a method for determining the influence of the inclination angle of a piston flowmeter on flow measurement comprises the following steps:

[0048] An air source, an air inlet pipeline 1, a first branch 2 and a second branch 3 are configured to output two air flows;

[0049] Two mass flow controllers MFC are configured, namely a first mass flow controller 4 and a second mass flow controller 5, which are respectively arranged on two branches for outputting two stable airflows;

[0050] A first gas circuit control valve 6 and a second gas circuit control valve 7 are respectively arranged on the two branches to control the on and off of the airflow in the two branches;

[0051] A piston flow meter 9 is configured, and the two branches converge to the convergent gas path 8 at the end and then are sent to the piston flow meter 9;

[0052] An angle adjustment mechanism 10 and an angle measuring device 11 are configured to adjust the inclination angle of the piston flowmeter and measure the inclination angle of the piston flowmeter respectively;

[0053] A constant temperature and humidity chamber 12 is configured to accommodate the above-mentioned components in the constant temperature and humidity chamber 12 to avoid the influence of other environmental parameters on the measurement.

[0054] The angle adjustment mechanism includes a base 10-1 and lifting rods 10-2 arranged at four corners of the base, the bottom ends of the lifting rods 10-2 are fixed to the base 10-1, and the top ends of the four lifting rods 10-2 are respectively hinged to the four bottom feet of the piston flowmeter 9. The angle measuring device 11 includes an inclination sensor or an angle measuring instrument set for the piston flowmeter.

[0055] Set up the calculation model:

[0056] q m =ρ(P a ,T)q V (1)

[0057]

[0058]

[0059] q*m1+m2+qmL=q*m1+qmL+q*m2+qmL

[0060] qmL=q*m1+m2-(q*m1+q*m2) (4)

[0061] In formulas (1)-(4), q m is the mass flow rate, P ais atmospheric pressure, T is the gas temperature inside the piston cylinder, ρ(P a ,T) is the atmospheric pressure P a , gas density at temperature T, q V is the volume flow rate, t is the measurement time interval, V is the volume traveled by the piston in the time interval t, q L is the leakage volume flow rate, q mL is the leakage mass flow rate, and the ones with * are the uncorrected readings of the piston flowmeter;

[0062] Calculation process:

[0063] Step (a) The piston flow meter is set vertically with an inclination angle of 0 relative to the base.

[0064] Among them, when the first gas circuit control valve 6 is opened and the second gas circuit control valve 7 is closed, q*m1 can be obtained; when both the first gas circuit control valve 6 and the second gas circuit control valve 7 are opened, q*m1+m2 can be obtained; when the second gas circuit control valve 7 is opened and the first gas circuit control valve 6 is closed, q*m2 can be obtained; qmL1 can be calculated by formula (4), and qL1 can be calculated according to formula (3);

[0065] Multiple qmL can be obtained by cycling through the following measurement sequence:

[0066] Group 1:

[0067] (1) Open the first gas circuit control valve 6, close the second gas circuit control valve 7, and record q*m1

[0068] (2) The first gas circuit control valve 6 and the second gas circuit control valve 7 are both open, and q*m1+m2 is recorded.

[0069] (3) Open the second gas circuit control valve 7, close the first gas circuit control valve 6, and record q*m2

[0070] qmL1 can be calculated by formula (4), and qL1 can be calculated by formula (3);

[0071] Group 2:

[0072] (4) The first gas circuit control valve 6 and the second gas circuit control valve 7 are both open, and q*m1+m2 is recorded.

[0073] (5) Open the second gas circuit control valve 7, close the first gas circuit control valve 6, and record q*m2

[0074] (6) Open the first gas circuit control valve 6, close the second gas circuit control valve 7, and record q*m1

[0075] qmL2 can be calculated from formula (4), and qL2 can be calculated from formula (3):

[0076] Group 3:

[0077] (7) Open the second gas circuit control valve 7, close the first gas circuit control valve 6, and record q*m2

[0078] (8) Open the first gas circuit control valve 6, close the second gas circuit control valve 7, and record q*m1

[0079] (9) The first gas circuit control valve 6 and the second gas circuit control valve 7 are both open, and q*m1+m2 is recorded.

[0080] qmL3 can be calculated from formula (4), and qL3 can be calculated from formula (3):

[0081] The measurement cycle sequence is:

[0082] q*m1,q*m1+m2,q*m2

[0083] q*m1+m2,q*m2,q*m1

[0084] q*m2,q*m1,q*m1+m2

[0085] ……, measure N times in a cycle;

[0086] The final leakage flow is:

[0087] Step (b) tilting at a certain angle α;

[0088] The measurement sequence is the same as that in step (a);

[0089] Step (c) Measure the leakage flow rate q at multiple tilt angles L , we can get the influence of the inclination angle on the flow measurement of the piston flowmeter.

[0090] In order to more intuitively reflect the influence of the inclination angle, the leakage flow measured at different angles is compared with the leakage flow at 0° to generate a distribution diagram of the inclination angle and the leakage flow.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A method for determining the effect of the inclination angle of a piston flowmeter on flow measurement, characterized in that: The following steps are involved: Configure one gas source and two branches to output two gas flows; Two mass flow controllers are respectively arranged on two branches to output two stable airflows; Two gas circuit control valves A and B are respectively arranged on the two branches to control the on and off of the airflow in the two branches; A piston flow meter is configured, and the two branches converge at the end and are sent to the piston flow meter; An angle adjustment mechanism and an angle measuring device are configured to adjust the inclination angle of the piston flowmeter and measure the inclination angle of the piston flowmeter respectively; Set up the calculation model: what m =ρ(P a ,T)q V (1) q*m1+m2+qmL=q*m1+qmL+q*m2+qmL qmL=q*m1+m2-(q*m1+q*m2) (4) In formulas (1)-(4), q m is the mass flow rate, P a is atmospheric pressure, T is the gas temperature inside the piston cylinder, ρ(P a ,T) is the atmospheric pressure P a , gas density at temperature T, q V is the volume flow rate, t is the measurement time interval, V is the volume traveled by the piston in the time interval t, q L is the leakage volume flow rate, q mL is the leakage mass flow rate, and the ones with * are the uncorrected readings of the piston flowmeter; Calculation process: Step (a) The inclination angle of the piston flowmeter is 0, Among them, open valve A, close valve B, and get q*m1; open valve A and valve B, and get q*m1+m2; open valve B, close valve A, and get q*m2; qmL1 can be calculated from formula (4), and qL1 can be calculated from formula (3); Multiple qmL can be obtained by cycling through the following measurement sequence: The measurement cycle sequence is: The first group: q*m1, q*m1+m2, q*m2 The second group: q*m1+m2, q*m2, q*m1 The third group: q*m2, q*m1, q*m1+m2 ……, measure N times in a cycle; The final leakage volume flow rate is: Step (b) tilting at a certain angle α; The measurement sequence is the same as that in step (a); Step (c) Measure the leakage volume flow rate q at multiple tilt angles L , we can get the influence of the inclination angle on the flow measurement of the piston flowmeter.

2. The method for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to claim 1, characterized in that: In step (a), the piston flow meter is arranged vertically.

3. The method for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to claim 2, characterized in that: In step (c), the leakage volume flow rates measured at different angles are compared with the leakage volume flow rate at 0° to generate a distribution diagram of the tilt angle and the leakage volume flow rate.

4. The method for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to any one of claims 1 to 3, characterized in that: The measurement environment is a constant temperature and humidity environment.

5. The method for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to claim 4, characterized in that: It comprises a constant temperature and humidity box, in which the branch, mass flow controller, gas path control valve, piston flow meter, angle adjustment mechanism and angle measuring device are all located.

6. A device for determining the effect of the inclination angle of a piston flowmeter on flow measurement, characterized in that: A method for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to claim 1 is used to implement the method, comprising an intake pipeline, a first branch, a second branch, a first mass flow controller, a second mass flow controller, a first gas path control valve, a second gas path control valve, a converging gas path, a piston flowmeter, an angle adjustment mechanism and an angle measuring device, wherein the intake pipeline connects the first branch and the second branch, the first mass flow controller and the first gas path control valve are installed in series on the first branch, the second mass flow controller and the second gas path control valve are installed in series on the second branch, the first branch and the second branch are connected to the converging gas path, the converging gas path is connected to the piston flowmeter, the angle adjustment mechanism is used to adjust the angle of the piston flowmeter, and the angle measuring device is used to detect the inclination angle of the piston flowmeter.

7. The device for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to claim 6, characterized in that: It also includes a constant temperature and humidity chamber, in which the air intake pipeline, the first branch, the second branch, the first mass flow controller, the second mass flow controller, the first gas path control valve, the second gas path control valve, the converging gas path, the piston flowmeter, the angle adjustment mechanism and the angle measurement device are all arranged.

8. The device for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to claim 7, characterized in that: The angle adjustment mechanism comprises a base and lifting rods arranged at four corners of the base, the bottom ends of the lifting rods are fixed to the base, and the top ends of the four lifting rods are respectively hinged to four bottom feet of the piston flowmeter.

9. The device for determining the influence of the inclination angle of a piston flowmeter on flow measurement according to claim 8, characterized in that: The angle measuring device comprises an inclination sensor or an angle measuring instrument arranged for the piston flow meter.

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