A gas flow standard device with high and low pressure dual calibration sections and calibration method thereof

Abstract

A gas flow standard device with high and low pressure dual calibration sections and a calibration method thereof, in the field of gas flow measurement calibration and verification, the present invention aims at the defects that the existing flow meter can only be calibrated under positive pressure conditions, has a narrow calibration range and high cost, and provides a flow standard device with high and low pressure dual calibration sections and a calibration method thereof. In the present invention, the outlet of the high-pressure gas source is connected with the high-pressure stop valve, the high-pressure regulating valve, the adjustable flow valve, the high-pressure calibration section, the stagnation container, the low-pressure calibration section, the low-pressure regulating valve, the low-pressure stop valve and the vacuum gas source in sequence, and the high-pressure calibrated flow meter is arranged in the high-pressure calibration section; the critical flow sonic nozzle standard meter and the branch stop valve are arranged in the stagnation container, and the low-pressure calibrated flow meter is arranged in the low-pressure calibration section, and the critical state high-pressure flow meter, the non-critical state high-pressure flow meter and the low-pressure flow meter are calibrated by adjusting the high-pressure calibrated flow meter and the low-pressure calibrated flow meter. The present invention is mainly used for calibrating and verifying gas flow.

Description

Technical Field

[0001] The invention belongs to the field of gas flow measurement calibration and verification, and in particular relates to a flow standard device of a critical flow nozzle providing high- and low-pressure dual calibration sections and a calibration method thereof. Background Art

[0002] Accurate measurement of gas flow is widely needed in the fields of petroleum, natural gas, chemical industry, energy conservation, environmental protection, aerospace, etc. Some flow meters have a wide range of working conditions. For example, at the same mass flow rate, they may work under different stagnation pressure conditions. Conventional negative pressure or positive pressure gas flow calibration devices cannot fully meet the calibration requirements of some flow meters in terms of calibration flow capacity range, calibration accuracy, calibration working condition range, etc. The utility model patent with publication number CN104501917A discloses an ultra-large-caliber sonic nozzle group gas flow meter calibration device, which adopts the negative pressure sonic nozzle principle, but its calibrated meter is located upstream of the standard meter, and the calibrated pressure condition is only atmospheric pressure. The utility model patent with publication number CN 103791951A discloses a positive pressure standard gas flow meter and a positive pressure standard gas flow measurement method, and the calibrated meter can also only be located on one side of the standard meter. The above two types of sonic nozzle flow standard devices are greatly restricted in terms of flow range and calibrated pressure working condition range, and fail to fully utilize the capacity of the sonic nozzle standard meter. The utility model patent with publication number CN108444576 A discloses a parallel structure of a dual-gas flow standard device. The utility model adopts a combination of two flow standard devices of different principles to increase the flow range. This solution has high requirements on technology and cost, and the achievable calibration conditions are limited. It also cannot meet some actual calibration needs.

[0003] Therefore, there is a need for a flow standard device with high and low pressure dual calibration sections and a calibration method thereof that can improve the calibration capability and meet special calibration requirements. Summary of the invention

[0004] In view of the defects of existing flow meters that can only be calibrated under positive pressure conditions, have a narrow calibration range and are relatively expensive, the present invention provides a flow standard device with high and low pressure dual calibration sections and a calibration method thereof that can improve the calibration capability, expand the calibration range, have low cost and meet special calibration needs.

[0005] The technical scheme of a gas flow standard device with high and low pressure dual calibration sections and a calibration method thereof involved in the present invention is as follows:

[0006] The present invention relates to a gas flow standard device with high-low pressure dual calibration sections, which comprises a high-pressure gas source, a high-pressure stop valve, a high-pressure regulating valve, an adjustable flow valve, a high-pressure calibrated flow meter, a high-pressure calibration section, a stagnation container, a critical flow sonic nozzle standard meter, a branch stop valve, a low-pressure calibrated flow meter, a low-pressure calibration section, a low-pressure regulating valve, a low-pressure exhaust valve, a low-pressure stop valve and a vacuum gas source, wherein the outlet of the high-pressure gas source is connected with the high-pressure stop valve, the high-pressure regulating valve, the adjustable flow valve, the high-pressure calibration section, the stagnation container, the low-pressure calibration section, the low-pressure regulating valve, the low-pressure stop valve and the vacuum gas source in sequence,

[0007] The high-pressure calibrated flow meter is disposed in the high-pressure calibration section, or the high-pressure calibrated flow meter is located downstream of the adjustable flow valve and upstream of the stagnation vessel;

[0008] The critical flow sonic nozzle standard gauge and the branch stop valve are arranged in a stagnation container, the inlet of the critical flow sonic nozzle standard gauge is connected to the upstream of the stagnation container, the outlet of the critical flow sonic nozzle standard gauge is connected to the inlet of the branch stop valve, and the outlet of the branch stop valve is connected to the inlet of the low-pressure calibration section; the low-pressure calibrated flowmeter is arranged in the low-pressure calibration section, and the low-pressure calibrated flowmeter is located upstream of the low-pressure regulating valve and downstream of the branch stop valve; the inlet of the low-pressure exhaust valve is connected between the low-pressure regulating valve and the low-pressure stop valve.

[0009] Further: the critical flow sonic nozzle standard table includes five passages, the five passages are specifically one nozzle passage, two nozzle passages, four nozzle passages, one eight nozzle passage and two eight nozzle passages, there are five branch stop valves, and the five branch stop valves are respectively connected to the downstream of the five passages.

[0010] Furthermore: the high-pressure calibrated flow meter is located upstream of the adjustable flow valve and downstream of the high-pressure regulating valve.

[0011] A calibration method for a gas flow standard device having high and low pressure dual calibration sections, comprising the following steps:

[0012] Step 1: Use the high-pressure flow meter to calibrate the critical state high-pressure flow meter;

[0013] Step 2: Use the high-pressure calibrated flowmeter to calibrate the non-critical high-pressure flowmeter;

[0014] Step 3: Use the low-pressure flowmeter to be calibrated to calibrate the low-pressure flowmeter.

[0015] Further: in step one, it includes the following steps:

[0016] Step 11: The high-pressure calibrated flow meter is located downstream of the adjustable flow valve and upstream of the stagnation container, and the low-pressure calibration section downstream of the stagnation container is connected by an equal straight pipe;

[0017] Step 1 and 2: Open the high-pressure stop valve and adjust the high-pressure regulating valve to maintain a stable high pressure before the adjustable flow valve;

[0018] Step 13: Adjust the adjustable flow valve so that the pressure before the high-pressure calibrated flow meter reaches the calibration working pressure;

[0019] Step 14: Partially or completely open the downstream branch stop valve to make the mass flow rate out of the critical flow sonic nozzle standard table equal to the calibrated mass flow rate;

[0020] Step 15: Adjust the downstream low-pressure regulating valve and low-pressure exhaust valve to fully open to allow the air flow to flow out; at this time, use the mass flow rate reserved in the critical flow sonic nozzle standard table to calibrate or verify the critical high-pressure calibrated flow meter.

[0021] Further: in step 2, it includes the following steps:

[0022] Step 21: The high-pressure calibrated flow meter is located upstream of the adjustable flow valve and downstream of the high-pressure regulating valve, and the low-pressure calibration section downstream of the stagnation container is connected by an equal straight pipe;

[0023] Step 22: Open the high-pressure stop valve and adjust the high-pressure regulating valve to make the pressure in front of the high-pressure calibrated flow meter reach the calibration pressure condition;

[0024] Step 2: Adjust the adjustable flow valve to change the mass flow rate in the pipeline to meet the flow calibration condition;

[0025] Step 24, partially or completely open the downstream branch stop valve, after the pressure in the stagnation container is stabilized, the mass flow rate flowing out of the critical flow sonic nozzle standard table is the calibrated mass flow rate;

[0026] Step 25: Adjust the downstream low-pressure regulating valve and low-pressure exhaust valve to fully open to allow the air to flow out; at this time, use the mass flow rate reserved in the critical flow sonic nozzle standard table to calibrate or verify the critical high-pressure calibrated flow meter.

[0027] Further: in step three, it includes the following steps:

[0028] Step 31: The low-pressure calibrated flowmeter is installed in the low-pressure calibration section, and the low-pressure calibrated flowmeter is located upstream of the low-pressure regulating valve and downstream of the branch stop valve, and the upstream high-pressure calibration section is connected by an equal straight pipe;

[0029] Step 32: Open the high-pressure stop valve, and adjust the high-pressure regulating valve and the adjustable flow valve to change the mass flow in the pipeline to meet the flow calibration working condition;

[0030] Step 3. Partially or completely open the downstream branch stop valve. After the pressure in the stagnation vessel stabilizes, the mass flow rate flowing out of the critical flow sonic nozzle standard table is the calibrated mass flow rate;

[0031] Step 3 and 4: adjust the low-pressure regulating valve and low-pressure stop valve at the downstream to fully open, so that the airflow flows into the vacuum air source;

[0032] Step 35. When calibrating the low-pressure calibrated flowmeter under non-critical positive and negative pressure conditions, it is necessary to adjust the downstream low-pressure regulating valve so that the pressure in front of the low-pressure calibrated flowmeter reaches the calibrated pressure condition. At this time, the vacuum air source needs to be turned on; use the mass flow rate flowing out of the critical flow sonic nozzle standard table to calibrate or verify the critical low-pressure calibrated flowmeter.

[0033] The beneficial effects of the gas flow standard device with high and low pressure dual calibration sections and the calibration method thereof involved in the present invention are:

[0034] The present invention relates to a gas flow standard device with high and low pressure dual calibration sections and a calibration method thereof. A reasonably designed pipeline valve configuration method is designed, a critical flow Venturi nozzle is used as a standard table of the flow standard device in the device, and a high pressure calibration section and a low pressure calibration section are respectively set by utilizing the characteristics of the pressure difference between the upstream and downstream of the sonic nozzle, so as to fully utilize the advantages of the existing positive pressure method and negative pressure method flow standard devices, greatly expand the working condition range of flow calibration and improve the calibration accuracy. The device can calibrate the flowmeter in a wider pressure and flow working condition range. First, under the same calibration capability, the cost of the standard flow device is reduced. If the high and low pressure calibration sections are placed on the same side of the upstream or downstream of the sonic nozzle, more and larger sonic nozzles are required to meet the flow calibration requirements, reducing the demand for sonic nozzle standard tables and reducing the construction cost. Secondly, the calibration capability of the flow standard device is expanded; the high pressure calibration section can expand the calibration range by changing the pressure, and the low pressure calibration section is set downstream of the same group of sonic nozzle standard tables, further expanding the pressure working condition range of the calibration. Furthermore, the actual working condition of the flowmeter can be simulated for calibration, which improves the calibration accuracy of the flowmeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is an overall schematic diagram of the device of the present invention;

[0036] Figure 2 It is the structural device diagram of the critical flow sonic nozzle standard table;

[0037] Figure 3 A schematic diagram of a specific implementation method for calibrating a critical state high pressure flow meter;

[0038] Figure 4 A schematic diagram of a specific implementation method for calibrating a non-critical high-pressure flowmeter;

[0039] Figure 5 A schematic diagram of a specific implementation method for calibrating a low-pressure flow meter;

[0040] Figure 6 To perform critical state high pressure flow meter calibration state diagram;

[0041] In the figure, 1 is a high-pressure gas source, 2 is a high-pressure stop valve, 3 is a high-pressure regulating valve, 4 is an adjustable flow valve, 5 is a high-pressure calibrated flow meter, 6 is a high-pressure calibration section, 7 is a stagnation container, 8 is a critical flow sonic nozzle standard table, 9 is a branch stop valve, 10 is a low-pressure calibrated flow meter, 11 is a low-pressure calibration section, 12 is a low-pressure regulating valve, 13 is a low-pressure exhaust valve, 14 is a low-pressure stop valve, 15 is a vacuum gas source, 81 is a nozzle passage, 82 is a nozzle passage, 83 is a four-nozzle passage, 84 is a No. 1 eight-nozzle passage, and 85 is a No. 2 eight-nozzle passage. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below in conjunction with the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0043] Example 1

[0044] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5The present embodiment is described. In the present embodiment, a gas flow standard device with high and low pressure dual calibration sections is involved in the present embodiment, which includes a high-pressure gas source 1, a high-pressure stop valve 2, a high-pressure regulating valve 3, an adjustable flow valve 4, a high-pressure calibrated flow meter 5, a high-pressure calibration section 6, a stagnation container 7, a critical flow sonic nozzle standard meter 8, a branch stop valve 9, a low-pressure calibrated flow meter 10, a low-pressure calibration section 11, a low-pressure regulating valve 12, a low-pressure exhaust valve 13, a low-pressure stop valve 14 and a vacuum gas source 15. The outlet of the high-pressure gas source 1 is connected to the high-pressure stop valve 2, the high-pressure regulating valve 3, the adjustable flow valve 4, the high-pressure calibration section 6, the stagnation container 7, the low-pressure calibration section 11, the low-pressure regulating valve 12, the low-pressure stop valve 14 and The vacuum air source 15 is connected in sequence, and the high-pressure calibrated flowmeter 5 is arranged in the high-pressure calibration section 6; the critical flow sonic nozzle standard gauge 8 and the branch stop valve 9 are arranged in the stagnation container 7, the inlet of the critical flow sonic nozzle standard gauge 8 is connected to the upstream of the stagnation container 7, the outlet of the critical flow sonic nozzle standard gauge 8 is connected to the inlet of the branch stop valve 9, and the outlet of the branch stop valve 9 is connected to the inlet of the low-pressure calibration section 11; the low-pressure calibrated flowmeter 10 is arranged in the low-pressure calibration section 11, and the low-pressure calibrated flowmeter 10 is located upstream of the low-pressure regulating valve 12 and downstream of the branch stop valve 9; the inlet of the low-pressure exhaust valve 13 is connected between the low-pressure regulating valve 12 and the low-pressure stop valve 14. By using a set of critical flow sonic nozzles, the calibration requirements of high-pressure working conditions and low-pressure working conditions can be achieved. For the same flow point, the flowmeter can be calibrated under high-pressure working conditions and low-pressure working conditions respectively, realizing real-time calibration, which not only reduces the cost of the device but also expands the calibration capacity. When calibrating a low-pressure flowmeter, the calibrated low-pressure flowmeter 10 is installed in the low-pressure calibration section 11, located upstream of the low-pressure regulating valve 12 and downstream of the branch stop valve 9, and the upstream high-pressure calibration section 6 is connected by an equal straight pipe. Open the high-pressure stop valve 2, adjust the high-pressure regulating valve 3 and the adjustable flow valve 4 to change the mass flow in the pipeline to meet the flow calibration working condition; partially or fully open the downstream branch stop valve 9, and after the pressure in the stagnation container 7 is stable, the mass flow flowing out of the critical flow Venturi nozzle standard table 8 is the calibrated mass flow; when calibrating a critical low-pressure flowmeter, the downstream low-pressure regulating valve 12 and the low-pressure stop valve 14 are fully opened to allow the airflow to flow into the vacuum air source 15. When calibrating a non-critical low-pressure flowmeter 10, it is necessary to adjust the downstream low-pressure regulating valve 12 so that the pressure before the calibrated flowmeter reaches the calibrated pressure working condition. Use the mass flow reserved in the critical flow Venturi nozzle standard table 8 to calibrate or verify the critical high-pressure flowmeter 10.

[0045] More specifically: the critical flow sonic nozzle standard gauge 8 includes five passages, the five passages are specifically a nozzle passage 81, a nozzle passage 82, a nozzle passage 83, a nozzle passage 84, a nozzle passage 85, and a branch stop valve 9, which are five and are connected to the downstream of the five passages respectively. The critical flow sonic nozzle standard gauge includes 23 Venturi sonic nozzles of the same throat diameter, which are divided into 5 passages. The first passage includes 1 sonic nozzle, the second passage includes 2 sonic nozzles, the third passage includes 4 sonic nozzles, the fourth passage includes 8 sonic nozzles, and the fifth passage includes 8 sonic nozzles. A branch stop valve 9 is installed downstream of each passage to control the on and off of the critical flow Venturi nozzle standard gauge. By opening these passages in combination, the continuous opening of 1 to 23 nozzles can be achieved. For example, opening 13 nozzles can be achieved by opening 1, 4, and 8 nozzles of the first, third, and fourth passages. Therefore, the adjustment of the flow rate through the sonic nozzle standard meter can be achieved by opening different numbers of nozzles. In addition, by adjusting the adjustable flow valve, the stagnation pressure in front of the nozzle can be changed, and the mass flow rate through the sonic nozzle standard meter can be further changed. Therefore, the size of the gas flow through the critical flow Venturi nozzle standard meter can not only be adjusted by the number of branch stop valves opened, but also by adjusting the stagnation pressure in the stagnation container by the upstream adjustable flow valve.

[0046] More specifically: the high-pressure calibrated flowmeter 5 is located downstream of the adjustable flow valve 4 and upstream of the stagnation container 7. When calibrating the critical state high-pressure flowmeter, the calibrated high-pressure flowmeter 5 is installed in the high-pressure calibration section 6, located downstream of the adjustable flow valve 4 and upstream of the stagnation container 7, and the downstream low-pressure calibration section 11 is connected by an equal straight pipe. Open the high-pressure stop valve 2, adjust the high-pressure regulating valve 3, so that the pressure in front of the adjustable flow valve 4 is kept stable and high; adjust the adjustable flow valve 4 so that the pressure in front of the calibrated high-pressure flowmeter 5 reaches the calibration working condition pressure; partially or completely open the downstream branch stop valve 9 so that the mass flow rate flowing out of the critical flow Venturi nozzle standard table 8 is equal to the calibrated mass flow rate; the downstream low-pressure regulating valve 12 and the low-pressure exhaust valve 13 are fully opened to allow the air flow to flow out. At this time, the mass flow rate reserved in the critical flow Venturi nozzle standard table 8 is used to calibrate or verify the critical type high-pressure flowmeter 5.

[0047] More specifically: the high-pressure calibrated flowmeter 5 is located upstream of the adjustable flow valve 4 and downstream of the high-pressure regulating valve 3. When calibrating a non-critical high-pressure flowmeter, the calibrated high-pressure flowmeter 5 is installed in the high-pressure calibration section 6, located upstream of the adjustable flow valve 4 and downstream of the high-pressure regulating valve 3, and the downstream low-pressure calibration section 11 is connected by an equal straight pipe. Open the high-pressure stop valve 2, adjust the high-pressure regulating valve 3, so that the pressure before the calibrated high-pressure flowmeter 5 reaches the calibration pressure condition; adjust the adjustable flow valve 4 to change the mass flow flowing in the pipeline to meet the flow calibration condition; partially or completely open the downstream branch stop valve 9, and after the pressure in the stagnation container 7 is stable, the mass flow flowing out of the critical flow Venturi nozzle standard table 8 is the calibrated mass flow; the downstream low-pressure regulating valve 12 and the low-pressure exhaust valve 13 are fully opened to allow the airflow to flow out. At this time, the mass flow reserved in the critical flow Venturi nozzle standard table 8 is used to calibrate or verify the critical type high-pressure flowmeter 5.

[0048] Example 2

[0049] This embodiment is described in conjunction with Example 1. In this embodiment, a calibration method for a gas flow standard device having high and low pressure dual calibration sections involved in this embodiment includes the following steps:

[0050] Step 1: Calibrate the critical state high pressure flowmeter using the high pressure calibrated flowmeter 5;

[0051] Step 2: Calibrate the non-critical high-pressure flowmeter using the high-pressure calibrated flowmeter 5;

[0052] Step 3: Use the low-pressure calibrated flowmeter 10 to calibrate the low-pressure flowmeter.

[0053] A gas flow standard device with high and low pressure dual calibration sections and a calibration method can be used for the calibration and verification of high pressure working flow meters and low pressure working flow meters. The total mass flow rate flowing through the standard meter can be calculated by the following formula:

[0054]

[0055] In the formula, q m is the mass flow rate; C dn is the sonic nozzle discharge coefficient (n = 1 ~ 23); D is the nominal diameter of the sonic nozzle throat; C * is the critical quantity function; P 0 is the stagnation temperature; T 0 is the stagnation temperature; R is the universal gas constant, 8.31441 J / (mol·K); M is the molar mass of the gas, kg / mol.

[0056] A high-pressure calibration section is set upstream of the critical flow venturi nozzle standard meter to install flow meters of different sizes working under high pressure conditions. The gas flowing through the high-pressure calibrated flow meter can be measured and calibrated through the downstream critical flow sonic nozzle standard meter. The size of the calibrated flow meter in the high-pressure calibration section is relatively small, with a maximum pressure of 3-5MPa and a maximum diameter of 200mm.

[0057] A high-pressure calibration section is set downstream of the critical flow venturi nozzle standard table to install flow meters of different sizes working under low-pressure conditions. The gas flowing through the low-pressure calibrated flow meter can be measured and calibrated by the upstream critical flow sonic nozzle standard table. The maximum working pressure of the calibrated flow meter in the low-pressure calibration section can reach 1MPa, the minimum working pressure can be 0.05MPa, and the maximum diameter can reach 400mm. Through this technical solution, a set of sonic nozzle standard tables can be fully utilized to realize the calibration of flow meters with a wide pressure range and a wide size range.

[0058] More specifically: when calibrating the critical state high pressure flowmeter, the high pressure calibrated flowmeter 5 is installed in the high pressure calibration section 6, located downstream of the adjustable throttle valve 4 and upstream of the stagnation container 7, and the downstream low pressure calibration section 11 is connected by an equal straight pipe. At this time, the critical flow venturi nozzle standard table 8 downstream of the adjustable throttle valve 4 and the stagnation container 7 is in a critical state. According to the principle of flow conservation in the pipeline, in order to make the high pressure calibrated flowmeter 5 reach the critical state, the pressure P01 upstream of the throttle valve 4 needs to be high enough. At this time, the following formula is satisfied, so when P01 is high enough, adjust A1 and A3, but A2 reaches the critical point.

[0059]

[0060]

[0061] Open the high-pressure stop valve 2, adjust the high-pressure regulating valve 3, so that the high pressure P01 in front of the adjustable throttle valve 4 is maintained stably; adjust the adjustable throttle valve 4 so that the pressure in front of the high-pressure calibrated flowmeter 5 reaches the calibration working condition pressure P02; partially or fully open the downstream branch stop valve 9 to change the flow area A3, and also adjust the pressure P03 in the stagnation container 7, so that the mass flow rate flowing out of the critical flow Venturi nozzle standard table 8 is equal to the calibrated mass flow rate; the downstream low-pressure regulating valve 12 and the low-pressure exhaust valve 13 are fully opened to allow the air flow to flow out. At this time, the mass flow rate reserved in the critical flow Venturi nozzle standard table 8 is used to calibrate or verify the critical type high-pressure flowmeter 5.

[0062] More specifically: When calibrating a high-pressure flowmeter in a non-critical state, the high-pressure flowmeter 5 to be calibrated is installed in the high-pressure calibration section 6, upstream of the adjustable throttle valve 4 and downstream of the high-pressure regulating valve 3. The downstream low-pressure calibration section 11 is connected by an equal straight pipe. Open the high-pressure stop valve 2 and adjust the high-pressure regulating valve 3 to make the pressure in front of the high-pressure flowmeter 5 to be calibrated reach the calibration pressure condition; adjust the adjustable throttle valve 4 to change the mass flow rate in the pipeline to meet the flow calibration condition; partially or fully open the downstream branch stop valve 9. After the pressure in the stagnation vessel 7 stabilizes, the mass flow rate flowing out of the critical flow Venturi nozzle standard meter 8 is the mass flow rate to be calibrated; fully open the downstream low-pressure regulating valve 12 and the low-pressure exhaust valve 13 to allow the air flow to flow out. At this time, use the mass flow rate flowing out of the critical flow Venturi nozzle standard meter 8 to calibrate or verify the critical type high-pressure flowmeter 5.

[0063] More specifically: When calibrating a low-pressure flowmeter, the low-pressure flowmeter 10 to be calibrated is installed in the low-pressure calibration section 11, upstream of the low-pressure regulating valve 12 and downstream of the branch stop valve 9. The upstream high-pressure calibration section 6 is connected by an equal straight pipe. Open the high-pressure stop valve 2 and adjust the high-pressure regulating valve 3 and the adjustable throttle valve 4 to change the mass flow rate in the pipeline to meet the flow calibration condition; partially or fully open the downstream branch stop valve 9. After the pressure in the stagnation vessel 7 stabilizes, the mass flow rate flowing out of the critical flow Venturi nozzle standard meter 8 is the mass flow rate to be calibrated; when calibrating a critical type low-pressure flowmeter, fully open the downstream low-pressure regulating valve 12 and the low-pressure stop valve 14 to allow the air flow to flow into the vacuum source 15. When calibrating the low-pressure flowmeter 10 under non-critical positive and negative pressure conditions, it is necessary to adjust the downstream low-pressure regulating valve 12 to make the pressure in front of the flowmeter to be calibrated reach the calibrated pressure condition. At this time, it is necessary to turn on the vacuum source 15. Use the mass flow rate flowing out of the critical flow Venturi nozzle standard meter 8 to calibrate or verify the critical type low-pressure flowmeter 10.

[0064] Embodiment 3

[0065] This embodiment is described in combination with Embodiment 1 and Embodiment 2.

[0066] 1) When calibrating a high-pressure flowmeter in a critical state, the high-pressure flowmeter 5 to be calibrated is located between the adjustable throttle valve 4 and the stagnation vessel 7. The actual state is similar to Figure 6 , the flowmeter to be calibrated is located at section A2, the adjustable throttle valve 4 is located at section A1, and the stagnation vessel 7 is the space in front of section A3. At this time, P01 > P02 > P03, A1 < A2 < A3, and A2 / A1 > k1, P01 / P03 > k2, where both k1 and k2 are values greater than 1; with the pipeline state set according to this area, as long as P01 is high enough, the flowmeter to be calibrated at section 2 can reach the critical state, that is, the sonic speed is reached at the throat. That is, it provides the ability to calibrate a critical flowmeter.

[0067] 2) When calibrating a non-critical high-pressure flowmeter, the high-pressure calibrated flowmeter 5 is located between the high-pressure regulating valve 3 and the adjustable flow valve 4. The actual state is similar to Figure 6 , the calibrated flow meter is located at section A2, and the adjustable flow valve 4 is located at section A1. At this time, A1>A2, A2<A3,P02≈P01> P03; According to the pipeline state set by this area, due to the throttling at section A1, the flow area at section A2 is larger, and section A2 can only be in a non-critical state. At this time, the ability to calibrate the critical flow flowmeter can be provided before section A1.

[0068] The flow quantities of the adjustable flow valve 4 and the critical flow venturi nozzle standard gauge 8 (at section 3) are both adjustable, which actually changes the area to match the pressure, further achieving a critical or non-critical state.

Claims

1. A gas flow standard device with high and low pressure dual calibration sections, characterized in that: It comprises a high-pressure gas source (1), a high-pressure stop valve (2), a high-pressure regulating valve (3), an adjustable flow valve (4), a high-pressure calibrated flow meter (5), a high-pressure calibration section (6), a stagnation container (7), a critical flow sonic nozzle standard meter (8), a branch stop valve (9), a low-pressure calibrated flow meter (10), a low-pressure calibration section (11), a low-pressure regulating valve (12), a low-pressure exhaust valve (13), a low-pressure stop valve (14) and a vacuum gas source (15). The outlet of the high-pressure gas source (1) is connected to the high-pressure stop valve (2), the high-pressure regulating valve (3), the adjustable flow valve (4), the high-pressure calibration section (6), the stagnation container (7), the low-pressure calibration section (11), the low-pressure regulating valve (12), the low-pressure stop valve (14) and the vacuum gas source (15) in sequence. The high-pressure calibrated flow meter (5) is arranged in the high-pressure calibration section (6), or the high-pressure calibrated flow meter (5) is located downstream of the adjustable flow valve (4) and upstream of the stagnation container (7); The critical flow sonic nozzle standard meter (8) and the branch stop valve (9) are arranged in the stagnation container (7), the inlet of the critical flow sonic nozzle standard meter (8) is connected to the upstream of the stagnation container (7), the outlet of the critical flow sonic nozzle standard meter (8) is connected to the inlet of the branch stop valve (9), and the outlet of the branch stop valve (9) is connected to the inlet of the low-pressure calibration section (11); the low-pressure calibrated flow meter (10) is arranged in the low-pressure calibration section (11), and the low-pressure calibrated flow meter (10) is located upstream of the low-pressure regulating valve (12) and downstream of the branch stop valve (9); the inlet of the low-pressure exhaust valve (13) is connected between the low-pressure regulating valve (12) and the low-pressure stop valve (14).

2. A gas flow standard device with high and low pressure dual calibration sections according to claim 1, characterized in that: The critical flow sonic nozzle standard table (8) includes five passages, and the five passages are specifically a nozzle passage (81), a nozzle passage (82), a nozzle passage (83), a nozzle passage No. 1 (84), and an eight-nozzle passage No. 2 (85). There are five branch stop valves (9), and the five branch stop valves (9) are respectively connected to the downstream of the five passages.

3. A gas flow standard device with high and low pressure dual calibration sections according to claim 2, characterized in that: The high-pressure calibrated flow meter (5) is located upstream of the adjustable flow valve (4) and downstream of the high-pressure regulating valve (3).

4. A calibration method for a gas flow standard device having high and low pressure dual calibration sections as claimed in claim 1, characterized in that: It includes the following steps: Step 1: Calibrate the critical state high pressure flow meter using the high pressure calibrated flow meter (5); Step 2: calibrating the non-critical high-pressure flowmeter using the high-pressure calibrated flowmeter (5); Step 3: calibrate the low-pressure flowmeter using the low-pressure flowmeter to be calibrated (10).

5. The calibration method of a gas flow standard device with high and low pressure dual calibration sections according to claim 4 is characterized in that: In step one, it includes the following steps: Step 11: The high-pressure calibrated flow meter (5) is located downstream of the adjustable flow valve (4) and upstream of the stagnation container (7), and the low-pressure calibration section (11) downstream of the stagnation container (7) is connected by an equal straight pipe; Step 1 and 2: Open the high-pressure stop valve (2) and adjust the high-pressure regulating valve (3) to maintain a stable high pressure before the adjustable flow valve (4); Step 13: adjust the adjustable flow valve (4) so ​​that the pressure before the high-pressure calibrated flow meter (5) reaches the calibration working pressure; Step 14: partially or completely open the downstream branch stop valve (9) to make the mass flow rate flowing out of the critical flow sonic nozzle standard table (8) equal to the calibrated mass flow rate; Step 15: fully open the downstream low-pressure regulating valve (12) and the low-pressure exhaust valve (13) to allow the air to flow out; at this time, the mass flow rate flowing out of the critical flow sonic nozzle standard table (8) is used to calibrate or verify the critical high-pressure calibrated flow meter (5).

6. The calibration method of a gas flow standard device with high and low pressure dual calibration sections according to claim 4, characterized in that: In step two, it includes the following steps: Step 21: The high-pressure calibrated flow meter (5) is located upstream of the adjustable flow valve (4) and downstream of the high-pressure regulating valve (3), and the low-pressure calibration section (11) downstream of the stagnation container (7) is connected by an equal straight pipe; Step 22: Open the high-pressure stop valve (2) and adjust the high-pressure regulating valve (3) so that the pressure before the high-pressure calibrated flow meter (5) reaches the calibration pressure condition; Step 23: adjust the adjustable flow valve (4) to change the mass flow rate flowing in the pipeline to meet the flow calibration working condition; Step 24, partially or completely open the downstream branch stop valve (9), after the pressure in the stagnation container (7) is stabilized, the mass flow rate flowing out of the critical flow sonic nozzle standard table (8) is the calibrated mass flow rate; Step 25: fully open the downstream low-pressure regulating valve (12) and the low-pressure exhaust valve (13) to allow the air to flow out; at this time, the mass flow rate flowing out of the critical flow sonic nozzle standard table (8) is used to calibrate or verify the non-critical high-pressure calibrated flowmeter (5).

7. The calibration method of a gas flow standard device with high and low pressure dual calibration sections according to claim 4, characterized in that: In step three, it includes the following steps: Step 31: The low-pressure calibrated flow meter (10) is installed in the low-pressure calibration section (11), and the low-pressure calibrated flow meter (10) is located upstream of the low-pressure regulating valve (12) and downstream of the branch stop valve (9), and the upstream high-pressure calibration section (6) is connected by an equal straight pipe; Step 32: Open the high-pressure stop valve (2), and adjust the high-pressure regulating valve (3) and the adjustable flow valve (4) to change the mass flow in the pipeline to meet the flow calibration working condition; Step 3. Partially or completely open the downstream branch stop valve (9). After the pressure in the stagnation container (7) is stabilized, the mass flow rate flowing out of the critical flow sonic nozzle standard gauge (8) is the mass flow rate to be calibrated; Step 34: adjust the downstream low-pressure regulating valve (12) and low-pressure stop valve (14) to fully open, so that the airflow flows into the vacuum air source (15); Step 35. When calibrating a low-pressure calibrated flow meter (10) under non-critical positive and negative pressure conditions, it is necessary to adjust the downstream low-pressure regulating valve (12) so that the pressure in front of the low-pressure calibrated flow meter (10) reaches the calibrated pressure condition. At this time, it is necessary to open the vacuum air source (15); use the mass flow rate flowing out of the critical flow sonic nozzle standard table (8) to calibrate or verify the non-critical low-pressure calibrated flow meter (10).

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