A double-bend pipe flow rate and pressure measurement structure and method

Abstract

The present invention provides a double-elbow flow pressure measurement structure and method, which can effectively solve the problems of high power consumption, high cost, large size and complicated installation of the whole machine, and can realize the detection of small flow; it includes an air intake pipe, and the air outlet end of the air intake pipe is provided with a small flow elbow sensor and a large flow elbow sensor arranged in parallel, the output end of the small flow elbow sensor is equipped with a small flow electric control valve, and the output end of the large flow elbow sensor is equipped with a large flow electric control valve, the center line angles of the two end faces of the elbow of the small flow elbow sensor and the large flow elbow sensor are both 90 degrees, and pressure sensors are installed at a 45-degree angle on the inner side wall of the elbow of the small flow elbow sensor and the large flow elbow sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of gas flow detection, and in particular to a double-elbow flow and pressure measurement structure and method thereof. Background Art

[0002] The development of gas energy has brought a lot of convenience and speed to people's lives, especially in cities, where gas has been delivered to almost every household, and the gas usage needs to be recorded by a gas meter.

[0003] Most gas meters use flow meters to detect gas flow. At present, someone has invented a household double-elbow gas meter using double-elbow pipes, which uses two differential pressure transmitters to realize double-elbow flow detection. The working principle of double-elbow flow detection is: when the flow is in a large flow range, a large-flow elbow is used, and when the flow is in a small flow range, a small-flow elbow is used. The flow signal output of the large and small elbows is a pulling force exerted by the fluid in the small-flow elbow on the inner wall of the elbow sensor; one part is an extrusion force exerted by the fluid on the outer wall of the small elbow sensor, and similarly, a pulling force exerted by the fluid in the large-flow elbow on the inner wall of the elbow sensor; the other part is an extrusion force exerted by the fluid on the outer wall of the large elbow sensor, so that a differential pressure value with the outside being positive and the inside being negative can be generated on the inside and outside of the elbow sensor. The differential pressure value is then measured using a differential pressure transmitter, and the true flow value of the fluid can be obtained through necessary conversion and calculation.

[0004] In summary, although two differential pressure transmitters are used to collect the differential pressure values ​​on the inside and outside of the elbow sensor, and then the real flow value of the fluid can be obtained by switching the large and small elbows, it will lead to a large power consumption of the whole machine. At the same time, for enterprises engaged in mass production, the cost is high, the volume is large, and the installation is complicated. The double-elbow detection structure used can only solve the problem of small flow output signal of gas meter and difficult testing. However, the flow detection output signal is still small when testing a smaller flow. For example, the household gas meter tests the natural gas flow under low pressure, low flow rate and low density conditions. The differential pressure signal value it can generate is very small, and its leakage flow is 0.004m 3 / h or less, the starting flow rate is 0.004m 3 / h, the minimum flow rate is 0.016m 3 / h, the density of natural gas is 0.7174Kg / m 3 Testing leakage flow and starting flow increases the difficulty of flow measurement. Obtaining accurate natural gas flow values ​​in the low differential pressure range is extremely difficult. Testing micro-flows using the current double-bend pipe working principle is not feasible, so a new double-bend pipe flow detection structure and new detection method with a simple structure and a different detection principle must be developed. Summary of the Invention

[0005] In response to the above problems, the present invention provides a double-bend pipe flow and pressure measurement structure and method, which can effectively solve the problems of high power consumption, high cost, large size and complex installation of the whole machine, and can realize small flow detection.

[0006] The technical solution provided by the present invention is as follows: a double-elbow flow pressure measurement structure, including an air inlet pipe, the air outlet end of the air inlet pipe is provided with a small flow elbow sensor and a large flow elbow sensor arranged in parallel, the output end of the small flow elbow sensor is equipped with a small flow electric control valve, the output end of the large flow elbow sensor is equipped with a large flow electric control valve, the angle between the center lines of the two end faces of the elbow of the small flow elbow sensor and the large flow elbow sensor is 90°, and pressure sensors are installed at a 45-degree angle on the inner side wall of the elbow of the small flow elbow sensor and the large flow elbow sensor.

[0007] Furthermore, the small flow elbow sensor includes a small flow air inlet section and a small flow air outlet section, and the small flow air inlet section and the small flow air outlet section are connected by a circular arc-shaped small elbow section. The large flow elbow sensor includes a large flow air inlet section and a large flow air outlet section, and the large flow air inlet section and the large flow air outlet section are connected by a circular arc-shaped large elbow section.

[0008] Furthermore, pressure holes are provided on the inner side walls of the small bend pipe section and the large bend pipe section, and pressure pipes are connected to the pressure holes. The two pressure sensors are respectively denoted as pressure sensor P1 and pressure sensor P2. The pressure sensors P1 and P2 are respectively installed on the small bend pipe section and the large bend pipe section through the corresponding pressure holes and pressure pipes.

[0009] Furthermore, the diameters of the pressure-taking holes provided on the inner side walls of the small curved pipe section and the large curved pipe section are no larger than 10% of the inner diameter of the corresponding curved pipe section.

[0010] Furthermore, the diameters of the small flow air inlet section, the small bend section, and the small flow air outlet section are the same, and the diameters of the large flow air inlet section, the large bend section, and the large flow air outlet section are the same;

[0011] Furthermore, the length of the small flow air inlet section is 3 to 5 times the diameter of the small bend section, and the length of the small flow air outlet section is 1 to 2 times the diameter of the small bend section; the length of the large flow air inlet section is 3 to 5 times the diameter of the large bend section, and the length of the large flow air outlet section is 1 to 2 times the diameter of the large bend section;

[0012] A method for measuring flow rate and pressure of a double-bend pipe, characterized by comprising:

[0013] When the air intake volume of the intake pipe is less than the set flow rate, the small flow electric control valve is opened and the large flow electric control valve is closed. At this time, the outlet pressure P1 of the small flow elbow sensor is 出 P2 进 -P1 离 ;

[0014] When the air intake volume of the intake pipe is greater than the set flow rate, the large flow electric control valve is opened and the small flow electric control valve is closed. At this time, the outlet pressure P2 of the large flow elbow sensor is 出 For: P1 进 -P2 离 ;

[0015] in,

[0016] P2 进 is the inlet pressure of the large flow elbow sensor when the large flow electric control valve is closed;

[0017] P1 离 The pressure generated on the inner wall of the small elbow section of the small flow elbow sensor when the large flow electric control valve is closed;

[0018] P1 进 is the inlet pressure of the small flow elbow sensor when the small flow electric control valve is closed;

[0019] P2 离 It is the pressure generated on the inner wall of the large elbow section of the large flow elbow sensor when the small flow electric control valve is closed.

[0020] Furthermore, when the large flow electric control valve is closed, the pressure measured by the pressure sensor P2 is the inlet pressure P2 of the large flow elbow sensor. 进 ;

[0021] Furthermore, when the small flow electric control valve is closed, the pressure measured by the pressure sensor P1 is the inlet pressure P1 of the small flow elbow sensor. 进 ;

[0022] Furthermore, when there is no fluid flow in the small flow elbow sensor and the large flow elbow sensor: P2 进 =P1 出 .

[0023] The beneficial effect of the present invention is that it uses two miniature pressure sensors to replace the structure of using a differential pressure transmitter on the inside and outside of the existing elbow sensor, that is, pressure sensors are installed at a 45-degree angle on the inner side wall of the elbow of the small flow elbow sensor and the large flow elbow sensor, thereby effectively realizing small flow detection, and has the characteristics of low cost, small space occupation, low power consumption of the whole machine, improved accuracy, simple structure, firmness and reliability, and easy installation, and has good economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention;

[0025] Figure 2 It is a schematic diagram of the local structure of the present invention. DETAILED DESCRIPTION

[0026] like Figure 1 、 Figure 2 As shown, the present invention provides a double-elbow flow and pressure measurement structure, including an air inlet pipe 1, wherein the air outlet end of the air inlet pipe 1 is provided with a small-flow elbow sensor 2 and a large-flow elbow sensor 3 arranged in parallel, the output end of the small-flow elbow sensor 2 is provided with a small-flow electric-controlled valve 4, and the output end of the large-flow elbow sensor 3 is provided with a large-flow electric-controlled valve 5, the included angle between the center lines of the two end surfaces of the elbows of the small-flow elbow sensor 2 and the large-flow elbow sensor 3 is 90°, a pressure sensor P1 is installed at a 45-degree angle on the inner side wall of the elbow of the small-flow elbow sensor 2, and a pressure sensor P2 is installed at a 45-degree angle on the inner side wall of the elbow of the large-flow elbow sensor 3.

[0027] The small flow elbow sensor 2 includes a small flow air inlet section 6 and a small flow air outlet section 7, and the small flow air inlet section 6 and the small flow air outlet section 7 are connected by a circular arc-shaped small elbow section 8. The large flow elbow sensor 3 includes a large flow air inlet section 9 and a large flow air outlet section 10, and the large flow air inlet section 9 and the large flow air outlet section 10 are connected by a circular arc-shaped large elbow section 11; pressure holes 12 are provided on the inner side walls of the small elbow section 8 and the large elbow section 11, and a pressure pipe 13 is connected to the pressure hole 12. The pressure sensor P1 and the pressure sensor P2 are respectively installed on the small elbow section 8 and the large elbow section 11 through the corresponding pressure holes 12 and the pressure pipe 13.

[0028] The apertures of the pressure holes 12 opened on the inner walls of the small bend section 8 and the large bend section 11 are not greater than 10% of the inner diameter of the corresponding bend section; the diameters of the small flow air inlet section 6, the small bend section 8, and the small flow air outlet section 7 are the same, and the diameters of the large flow air inlet section 9, the large bend section 11, and the large flow air outlet section 10 are the same; the length of the small flow air inlet section 6 is 3 to 5 times the diameter of the small bend section 8, and the length of the small flow air outlet section 7 is 1 to 2 times the diameter of the small bend section 8; the length of the large flow air inlet section 9 is 3 to 5 times the diameter of the large bend section 11, and the length of the large flow air outlet section 10 is 1 to 2 times the diameter of the large bend section 11.

[0029] A method for measuring flow rate and pressure of a double-bend pipe, comprising:

[0030] When the large flow electric control valve 5 is closed, the fluid flow state when using pressure sensor P1 and pressure sensor P2 is:

[0031] Specifically, when the air intake volume of the intake pipe 1 is less than the set flow rate, the small flow electric control valve 4 is opened and the large flow electric control valve 5 is closed. At this time, the pressure measured by the pressure sensor P2 is equivalent to the inlet pressure of the intake pipe, that is, the pressure on the inner wall of the large bend section 11 of the large flow bend sensor 3 is P2. 进 ;

[0032] The outlet pressure P1 of the small flow elbow sensor 2 when there is fluid flowing 出 P2 进 -P1 离 ;

[0033] Among them, P1 离 It is the pressure generated on the inner wall of the small bend section 8 of the small flow elbow sensor 2 when the large flow electric control valve 5 is closed; that is, when the large flow electric control valve 5 is closed, the medium passes through the small flow elbow sensor 2, and the fluid exerts a centrifugal force on the inner wall of the small bend section 8 of the small flow elbow sensor 2. This centrifugal force can generate a pressure on the inner wall of the small bend section 8, which is P1 离 ; and in the state of fluid flow, P1 离 =P2 进 -P1 出 .

[0034] When the low-flow electric control valve 4 is closed, the fluid flow state when using pressure sensors P1 and P2 is:

[0035] Specifically, when the air intake volume of the intake pipe 1 is greater than the set flow rate, the large flow electric control valve 5 is opened and the small flow electric control valve 4 is closed. At this time, the pressure measured by the pressure sensor P1 is equivalent to the inlet pressure of the intake pipe, that is, the pressure on the inner wall of the small bend section 8 of the small flow bend sensor 2 is P1. 进 ;

[0036] The outlet pressure P2 of the large flow elbow sensor 3 when there is fluid flowing 出 For: P1 进 -P2 离 ;

[0037] Among them, P2 离 It is the pressure generated on the inner wall of the large elbow section 11 of the large flow elbow sensor 3 when the small flow electric control valve 4 is closed;

[0038] That is to say, when the small flow electric control valve 4 is closed, the medium passes through the large flow elbow sensor 3, and the fluid exerts a centrifugal force on the inner wall of the large elbow section 11 of the large flow elbow sensor 3. This centrifugal force can generate a pressure on the inner wall of the large elbow section 11, which is P2. 离 ; and in the state of fluid flow, P2 离 =P1 进 -P2 出 .

[0039] Small flow elbow sensor 2 and large flow elbow sensor 3 are in the state of no fluid flow:

[0040] That is, when P20-P10=0: P2 进 =P1 出 .

[0041] P10 and P20 are the pressure values ​​displayed by the pressure sensor P1 and the pressure sensor P2 when there is no fluid flow, respectively, when the small flow elbow sensor 2 and the large flow elbow sensor 3 are in the state of no fluid flow.

[0042] The present invention adopts pressure sensor P1 and pressure sensor P2 to replace the existing differential pressure transmitter structure and method. Its advantage is that it is not limited by installation distance, unlike the differential pressure transmitter which is limited by structural distance. At the same time, it can achieve higher flow detection accuracy. Its principle is:

[0043] Since the differential pressure transmitter directly displays the inlet and outlet pressure difference of the elbow, that is, P 差 , when the two pressure sensors and differential pressure transmitter have the same accuracy, that is: P 差 =P2=P1,

[0044] The pressure difference between the pressure sensor P1 and the pressure sensor P2 in the present invention is: P2-P1 or P1-P2.

[0045] When P1=P2, the error generated is: P2-P1=0 or P1-P2=0.

[0046] Therefore, the accuracy of the differential pressure transmitter must reach the pressure difference accuracy generated by the two pressure sensors, which requires the purchase of a higher-precision differential pressure transmitter.

[0047] Therefore, the structures of the pressure sensors P1 and P2 of the present invention can achieve high flow detection accuracy at low cost.

[0048] In the present invention, a practical calibration test is conducted on the small flow elbow sensor 2 and the large flow elbow sensor 3 according to the above technical solution, as shown in Table 1 below:

[0049]

[0050] In the above table, thin 1 and thin 1 respectively represent the first set of data measured by the small flow elbow sensor 2 and the large flow elbow sensor 3, and thin and thick only refer to the small flow elbow sensor 2 and the large flow elbow sensor 3 in this solution.

[0051] This embodiment takes 5 groups of test data measured by small flow elbow sensor 2 and large flow elbow sensor as examples. From the practical calibration test data, it can be seen that when the outlet pressure of the thin tube (that is, the small flow elbow sensor 2) is detected to be 1.2 Pa, the minimum flow rate can be detected to be 3.45 L / m 3 / h, so the detection structure and method of the present invention can solve the problem of low differential pressure signal of small flow rate.

[0052] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0053] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for measuring flow rate and pressure using a double-bend pipe, characterized in that: It comprises a double-elbow flow pressure measurement structure, the double-elbow flow pressure measurement structure comprises an air inlet pipe, the outlet end of the air inlet pipe is provided with a small flow elbow sensor and a large flow elbow sensor arranged in parallel, the output end of the small flow elbow sensor is provided with a small flow electric control valve, the output end of the large flow elbow sensor is provided with a large flow electric control valve, the angle between the center lines of the two end faces of the elbow of the small flow elbow sensor and the large flow elbow sensor is 90°, and a pressure sensor is installed at a 45-degree angle on the inner side wall of the elbow of the small flow elbow sensor and the large flow elbow sensor; the small flow elbow sensor comprises a small flow intake section and a small flow air outlet section, the small flow air inlet section and the small flow air outlet section are connected by a circular arc-shaped small bend pipe section, the large flow bend pipe sensor includes a large flow air inlet section and a large flow air outlet section, the large flow air inlet section and the large flow air outlet section are connected by a circular arc-shaped large bend pipe section; pressure holes are provided on the inner side walls of the small bend pipe section and the large bend pipe section, and a pressure guiding pipe is connected to the pressure hole. The two pressure sensors are respectively recorded as pressure sensor P1 and pressure sensor P2, and the pressure sensor P1 and pressure sensor P2 are respectively installed on the small bend pipe section and the large bend pipe section after being matched with the corresponding pressure holes and pressure guiding pipes; The method further comprises: When the air intake volume of the intake pipe is less than the set flow rate, the small flow electric control valve is opened and the large flow electric control valve is closed. At this time, the outlet pressure P1 of the small flow elbow sensor is 出 P2 进 - P1 离 ; When the air intake volume of the intake pipe is greater than the set flow rate, the large flow electric control valve is opened and the small flow electric control valve is closed. At this time, the outlet pressure P2 of the large flow elbow sensor is 出 For: P1 进 - P2 离 ; in, P2 进 is the inlet pressure of the large flow elbow sensor when the large flow electric control valve is closed; P1 离 The pressure generated on the inner wall of the small elbow section of the small flow elbow sensor when the large flow electric control valve is closed; P1 进 is the inlet pressure of the small flow elbow sensor when the small flow electric control valve is closed; P2 离 It is the pressure generated on the inner wall of the large elbow section of the large flow elbow sensor when the small flow electric control valve is closed.

2. A double-bend pipe flow rate and pressure measurement method according to claim 1, characterized in that: The diameters of the pressure-taking holes opened on the inner side walls of the small bend pipe section and the large bend pipe section are no greater than 10% of the inner diameter of the corresponding bend pipe section.

3. The method for measuring flow rate and pressure using a double-bend pipe according to claim 1, wherein: The diameters of the small flow air inlet section, the small bend section, and the small flow air outlet section are the same; the diameters of the large flow air inlet section, the large bend section, and the large flow air outlet section are the same.

4. The method for measuring flow rate and pressure using a double-bend pipe according to claim 1, wherein: The length of the small flow air inlet section is 3 to 5 times the diameter of the small bend section, and the length of the small flow air outlet section is 1 to 2 times the diameter of the small bend section; the length of the large flow air inlet section is 3 to 5 times the diameter of the large bend section, and the length of the large flow air outlet section is 1 to 2 times the diameter of the large bend section.

5. The method for measuring flow rate and pressure using a double-bend pipe according to claim 1, wherein: When the large flow electric control valve is closed, the pressure measured by the pressure sensor P2 is the inlet pressure P2 of the large flow elbow sensor. 进 .

6. A double-bend pipe flow rate and pressure measurement method according to claim 1, characterized in that: When the small flow electric control valve is closed, the pressure measured by the pressure sensor P1 is the inlet pressure P1 of the small flow elbow sensor. 进 .

7. The method for measuring flow rate and pressure using a double-bend pipe according to claim 1, wherein: When there is no fluid flowing in the small flow elbow sensor and the large flow elbow sensor: P2 进 = P1 出 。

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