Gas flow device for calibrating gas volumetric flowmeter

Abstract

The utility model relates to a gas flow device for calibrating a gas volumetric flowmeter. The gas flow device comprises a filter; a measured gas volumetric flowmeter; the first measuring assembly comprises a first pressure measuring piece and a first temperature measuring piece; a stagnation container, wherein a first stop valve is arranged between the stagnation container and the measured gas volumetric flowmeter; the throat diameters of the at least two sonic nozzles are different, and the at least two sonic nozzles are respectively communicated with the stagnation container; the confluence container is connected with at least two sonic nozzles, and a second stop valve is arranged between each sonic nozzle and the confluence container; the vacuum pump is connected with the outlet end of the confluence container, and a third stop valve is arranged between the vacuum pump and the confluence container. The calibration device is simple in structure, high in calibration result accuracy and good in stability; and the at least two sonic nozzles with different throat diameters are arranged, so that calibration of different flow points can be realized by combining the sonic nozzles with different throat diameters, and the calibration range is wider.

Description

Technical Field

[0001] The utility model relates to the technical field of flow meter calibration, in particular to a gas flow device for calibrating a gas volumetric flow meter. Background Art

[0002] Gas volumetric flowmeters are widely used in various fields, including energy, industry, environmental protection, scientific research, medical treatment and food processing. They are particularly suitable for occasions that require high-precision flow measurement.

[0003] The working principle of gas volumetric flowmeter is to use mechanical measuring elements to continuously divide the gas into a single known volume, and measure the total flow rate according to the number of times the volume portion is measured. When the gas passes through the flowmeter, a certain pressure difference will be generated between the inlet and outlet of the flowmeter. The rotating parts of the flowmeter (such as rotors or gears) rotate under the action of this pressure difference and discharge the gas from the inlet to the outlet. In this process, the gas fills the "metering space" of the flowmeter again and again, and then is continuously sent to the outlet. Under given flowmeter conditions, the volume of the metering space is determined. As long as the number of rotations of the rotating parts is measured, the cumulative value of the gas volume passing through the flowmeter can be obtained.

[0004] In the prior art, the measurement accuracy of gas volumetric flow meters is low and the measurement process is complicated and cumbersome.

[0005] Therefore, it is necessary to improve the prior art to overcome the above defects in the prior art. Utility Model Content

[0006] In view of this, the embodiment of the present application provides a gas flow device for calibrating a gas volumetric flow meter to solve at least one problem existing in the background technology, including:

[0007] a filter, connected to the air;

[0008] A volumetric flow meter for the gas to be measured, connected to the filter;

[0009] The first measuring assembly includes a first pressure measuring component arranged at an inlet end of the measured gas volumetric flow meter and a first temperature measuring component arranged at an outlet end of the measured gas volumetric flow meter;

[0010] A stagnation container connected to the measured gas volume flow meter, wherein a first stop valve is provided between the stagnation container and the measured gas volume flow meter;

[0011] at least two sonic nozzles, at least two of which have different throat diameters and are respectively connected to the stagnation container;

[0012] A confluence container connected to at least two of the sonic nozzles, wherein a second stop valve is provided between each of the sonic nozzles and the confluence container;

[0013] A vacuum pump is connected to the outlet end of the flow confluence container, and a third stop valve is provided between the vacuum pump and the flow confluence container.

[0014] Optionally, the above-mentioned gas flow device for calibrating a gas volumetric flow meter further includes a second pressure measuring device and a second temperature measuring device arranged on the stagnation container.

[0015] Optionally, the above-mentioned gas flow device for calibrating a gas volumetric flow meter further includes a third pressure measuring component arranged on the confluence container.

[0016] Optionally, the above-mentioned gas flow device for calibrating a gas volumetric flow meter further includes a silencer connected to the inlet end of the filter.

[0017] Optionally, in the above-mentioned gas flow device for calibrating a gas volumetric flowmeter, the stagnation container includes an inner tube and an outer tube sleeved on the outside of the inner tube and a fiberboard arranged between the outer tube and the inner tube, and the inner tube has a cavity, and the gas passing through the measured gas volumetric flowmeter flows into the cavity.

[0018] Compared with the prior art, the present application has the following beneficial effects: by setting a filter, a measured gas volumetric flow meter, a stagnation container, at least two sonic nozzles and a confluence container, and a vacuum pump, the operation of the vacuum pump can cause the pressure in the confluence container to continuously decrease, that is, change the pressure downstream of the sonic nozzle until the ratio of the downstream pressure to the upstream pressure of the sonic nozzle reaches a critical pressure ratio, and the gas mass flow rate passing through the sonic nozzle is no longer affected by the change in pressure, that is, the gas mass flow rate of the sonic nozzle is a constant value at this time, and the flow value passing through the sonic nozzle at this time is recorded and compared with the flow value of the measured gas volumetric flow meter to complete the calibration of the flow point. The calibration device has a simple structure, high accuracy of the calibration result, and good stability;

[0019] On the other hand, by providing at least two sonic nozzles with different throat diameters, calibration of different flow points can be achieved by combining sonic nozzles with different throat diameters, and the calibration range is wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a gas flow device for calibrating a gas volumetric flow meter shown in the present application. DETAILED DESCRIPTION

[0021] The exemplary embodiments disclosed in the present application will be described in more detail below. In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described; that is, all features of the actual embodiments are not described here, and known functions and structures are not described in detail.

[0022] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present application necessarily has the first element, component, region, layer or part.

[0023] Spatially relative terms such as "under", "beneath", "below", "under", "over", "above", etc., may be used herein for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures.

[0024] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "a", "an" and " / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0025] In order to thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0026] Please refer to Figure 1 As shown, a gas flow device for calibrating a gas volumetric flowmeter shown in this embodiment includes a filter 2 connected to the air, a volumetric flowmeter 4 of the gas to be measured connected to the filter 2, a first measuring assembly, a stagnation container 7 connected to the volumetric flowmeter 4 of the gas to be measured, at least two sonic nozzles 10, a confluence container 13 connected to the at least two sonic nozzles 10, and a vacuum pump 15 connected to the outlet end of the confluence container 13. Among them, a first stop valve 6 is also provided between the stagnation container 7 and the volumetric flowmeter 4 of the gas to be measured; a second stop valve 11 is provided between each sonic nozzle 10 and the confluence container 13; and a third stop valve 14 is provided between the vacuum pump 15 and the confluence container 13. The vacuum pump 15 can generate adsorption force when it works, so that the air can pass through the silencer 1, the filter 2, the measured gas volumetric flowmeter 4, the stagnation container 7, the sonic nozzle 10, and the confluence container 13 in sequence, and the vacuum pump 15 makes the pressure of the confluence container 13 continuously decrease, that is, the downstream pressure of the sonic nozzle 10 continuously decreases, until the ratio of the downstream pressure of the sonic nozzle 10 to the upstream pressure gradually reaches the critical pressure, and the gas flow rate reaches the maximum gas mass flow rate at the throat of the sonic nozzle 10, and at this time, no matter how the pressure in the confluence container 13 changes, it will not affect the maximum gas mass flow rate, and the calibration of this flow point is completed by measuring the maximum gas mass flow rate passing through the sonic nozzle 10 and comparing it with the flow of the measured gas volumetric flowmeter 4.

[0027] It should be noted that, in this embodiment, by providing the filter 2, it is possible to prevent large particles or foreign objects such as small mosquitoes and insects in the air from being inhaled, thereby ensuring the cleanliness and stability of the air source, thereby avoiding contamination of the entire device pipeline.

[0028] In this embodiment, the first stop valve 6 , the second stop valve 11 and the third stop valve 14 can all be connected to a controller, and the controller controls the on and off of the first stop valve 6 , the second stop valve 11 and the third stop valve 14 .

[0029] As described above, the first measuring component includes a first pressure measuring device 3 arranged at the inlet end of the measured gas volumetric flowmeter 4 and a first temperature measuring device 5 arranged at the outlet end of the measured gas volumetric flowmeter 4. The first pressure measuring device 3 is used to measure the gas pressure flowing through the measured gas volumetric flowmeter 4, and the first temperature measuring device 5 is used to measure the gas temperature flowing through the gas volumetric flowmeter 4 to ensure that during the calibration process of the calibration device, the pressure fluctuation does not exceed ±0.5% and the temperature change of the gas does not exceed ±1°C.

[0030] In an optional embodiment, the gas flow device for calibrating the gas volumetric flow meter also includes a second pressure measuring device 8 and a second temperature measuring device 9 arranged on the stagnation container 7, the second pressure measuring device 8 is used to measure the pressure upstream of the sonic nozzle 10, and the second temperature measuring device 9 is used to measure the gas temperature upstream of the sonic nozzle 10.

[0031] In an optional embodiment, the gas flow device for calibrating the gas volumetric flow meter further includes a third pressure measuring device 12 disposed on the confluence container 13 , and the third pressure measuring device 12 is used to measure the pressure of the gas flow downstream of the sonic nozzle 10 .

[0032] In an optional embodiment, the gas flow device for calibrating the gas volumetric flow meter further includes a muffler 1 connected to the inlet end of the filter 2. Since in this embodiment, negative pressure air intake is used during calibration, noise will be generated when air enters the pipeline of the calibration device, and the noise can be reduced by providing the muffler 1.

[0033] In an optional embodiment, the stagnation container 7 includes an inner tube, an outer tube sleeved outside the inner tube, and a fiberboard disposed between the outer tube and the inner tube, and the inner tube has a cavity, and the gas passing through the measured gas volume flow meter 4 flows into the cavity. By providing a double-layer structure of the stagnation container 7 and providing a sound-absorbing fiberboard between the double-layer structure, the noise generated during the operation of the entire device is further reduced.

[0034] In an optional embodiment, six sonic nozzles 10 are provided, and correspondingly, six second stop valves 11 are also provided. In this embodiment, each sonic nozzle 10 has a different throat diameter, that is, a different gas flow rate. For example, in this embodiment, the flow rates of the sonic nozzles 10 from top to bottom are 1m 3 / h、2m 3 / h、4m 3 / h、8m 3 / h, ..., 2 n m 3 / h (n is a natural number, generally not greater than 10), according to the "binary to decimal" method, different sonic nozzles 10 can be combined into various flow points, that is, the second stop valve 11 corresponding to the nozzle to be used is opened, and the second stop valve 11 corresponding to the nozzle not to be used is closed to achieve calibration of different flow points.

[0035] In summary, the calibration process of this embodiment is:

[0036] (1) Place the measured gas volume flow meter in the specified environment for more than 4 hours to ensure that the measured gas volume flow meter stabilizes to the ambient temperature.

[0037] (2) Open the first stop valve, the second stop valve and the third stop valve, the vacuum pump starts working, and the gas passes through the muffler, the filter, the measured gas volume flow meter, the stagnation container, the sonic nozzle, and the confluence container in sequence. The ventilation pre-operation is carried out for 5 minutes.

[0038] (3) Calibrate the first flow point, determine the sonic nozzle to be used according to the flow point, and close the second stop valve corresponding to the sonic nozzle that is not needed. Under the action of the vacuum pump, the pressure in the confluence container continues to decrease. When the ratio of the downstream pressure to the upstream pressure of the sonic nozzle reaches the critical pressure ratio, the gas flow rate reaches the local sonic speed at the throat of the sonic nozzle. At this time, the gas mass flow rate reaches the maximum. After that, the pressure in the confluence container changes, but the mass flow through the sonic nozzle remains unchanged. At this time, the air forms a stable loop and the test can be started. Record the flow value of the measured gas volume flow meter and the standard flow value of the sonic nozzle combination, calculate the error between the two, and complete the calibration of the flow point.

[0039] (4) Repeat the above steps to calibrate other flow points of the measured gas volumetric flow meter.

[0040] The above is only a specific implementation of the present application, and any improvements made based on the concept of the present application are deemed to be within the protection scope of the present application.

Claims

1. A gas flow device for calibrating a gas volumetric flow meter, characterized in that: include: a filter, connected to the air; A volumetric flow meter for the gas to be measured, connected to the filter; The first measuring assembly includes a first pressure measuring component arranged at an inlet end of the measured gas volumetric flow meter and a first temperature measuring component arranged at an outlet end of the measured gas volumetric flow meter; A stagnation container connected to the measured gas volume flow meter, wherein a first stop valve is provided between the stagnation container and the measured gas volume flow meter; at least two sonic nozzles, at least two of which have different throat diameters and are respectively connected to the stagnation container; A confluence container connected to at least two of the sonic nozzles, wherein a second stop valve is provided between each of the sonic nozzles and the confluence container; A vacuum pump is connected to the outlet end of the flow confluence container, and a third stop valve is provided between the vacuum pump and the flow confluence container.

2. A gas flow device for calibrating a gas volumetric flow meter according to claim 1, characterized in that: The apparatus further comprises a second pressure measuring device and a second temperature measuring device disposed on the stagnation vessel.

3. A gas flow device for calibrating a gas volumetric flow meter according to claim 1, characterized in that: The device further comprises a third pressure measuring device arranged on the confluence container.

4. A gas flow device for calibrating a gas volumetric flow meter according to claim 1, characterized in that: The device also includes a silencer connected to the inlet end of the filter.

5. A gas flow device for calibrating a gas volumetric flow meter according to claim 1, characterized in that: The stagnation container includes an inner tube, an outer tube sleeved outside the inner tube, and a fiberboard arranged between the outer tube and the inner tube. The inner tube has a cavity, and the gas passing through the measured gas volumetric flowmeter flows into the cavity.

Images