Gas flow device for calibrating thermal mass flowmeter

Abstract

The utility model relates to a gas flow device for calibrating a thermal mass flowmeter. The gas flow device comprises a gas storage tank; the gas control assembly comprises a stop valve, a flow regulating valve and a three-way valve; a pressure gauge; a thermometer; the detection assembly comprises a liquid storage tank, a gas guide pipe and a bell jar, a space exists between the bell jar and the liquid level of the liquid storage tank, the gas guide pipe penetrates through liquid, one end of the gas guide pipe is communicated with the gas storage tank, the other end of the gas guide pipe is communicated to the space above the liquid level in the bell jar, and the space can be changed according to the gas flow provided by the gas storage tank to enable the bell jar to move up and down; a photoelectric signal transmitter is arranged on the inner wall of the liquid storage tank in the height direction, and a plurality of baffles are evenly arranged on the side wall of the bell jar at intervals. Due to the fact that the volume between every two adjacent baffles is the known and fixed volume, the actual flow can be calculated by recording the time when the two adjacent baffles pass through the photoelectric signal transmitter, and calibration of the thermal mass flow meter can be achieved by comparing the actual flow with the reading of the thermal mass flow meter.

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 thermal mass flow meter. Background Art

[0002] Thermal mass flow meters have been widely used in many fields such as industrial production, environmental monitoring, medical health, aerospace, scientific research, etc. For example, in the chemical, petroleum, metallurgy, electric power and other industries, the flow of gas needs to be accurately measured and controlled to ensure the stability and safety of the production process. In environmental monitoring, thermal mass flow meters can be used to measure exhaust gas emissions to help companies comply with environmental regulations. In the medical field, thermal mass flow meters can be used for gas flow control in hospitals, laboratories and other places.

[0003] In order to ensure the measurement accuracy and stability of the thermal mass flow meter, the thermal mass flow meter should be calibrated regularly.

[0004] Therefore, it is necessary to improve the prior art to overcome the above defects in the prior art. Utility Model Content

[0005] In view of this, the embodiment of the present application provides a gas flow device for calibrating a thermal mass flow meter to solve at least one problem in the background technology, including:

[0006] Gas tanks, used to store gas;

[0007] A gas control assembly, comprising a stop valve, a flow regulating valve and a three-way valve, wherein the stop valve, the thermal mass flow meter to be measured, the flow regulating valve and the three-way valve are sequentially connected in series;

[0008] A pressure gauge connected to the gas control assembly and used to detect gas pressure;

[0009] A thermometer, connected to the pressure gauge, for detecting the gas temperature;

[0010] The detection component includes a liquid storage tank, an air duct and a bell jar at least partially located in the liquid of the liquid storage tank, there is a space between the bell jar and the liquid surface of the liquid storage tank, the air duct passes through the liquid, one end of which is connected to the gas storage tank, and the other end is connected to the space between the bell jar and the liquid surface, the space can be changed according to the gas flow provided by the gas storage tank to make the bell jar move up and down, a photoelectric transmitter is arranged in the height direction of the inner wall of the liquid storage tank, and a plurality of baffles are evenly spaced on the side wall of the bell jar.

[0011] Optionally, the above-mentioned gas flow device for calibrating a thermal mass flowmeter further comprises a compensation component;

[0012] The liquid storage tank has a top plate, and the top plate is provided with at least two fixed pulleys arranged at intervals and a traction rope arranged around the fixed pulley, one end of the traction rope is connected to the compensation component, and the other end of the traction rope is connected to the bell cover.

[0013] Optionally, in the above-mentioned gas flow device for calibrating a thermal mass flowmeter, a balancing liquid tank connected to the liquid storage tank is further provided on one side of the liquid storage tank, and at least a part of the compensation component is located in the balancing liquid tank.

[0014] Optionally, in the above-mentioned gas flow device for calibrating a thermal mass flowmeter, a scale is fixed on the side wall of the bell jar, and a plurality of baffles are evenly spaced apart and arranged on the scale.

[0015] Compared with the prior art, the present application has the following beneficial effects: by providing a liquid storage tank, an air duct and a bell jar, one end of the air duct is connected to the gas storage tank, and the other end can be connected to the space formed between the liquid surface of the liquid storage tank and the bell jar, so that the gas in the gas storage tank can be transported to the space by the air duct after passing through the thermal mass flowmeter to be measured, the volume of the space changes and the bell jar rises, thereby driving a number of baffles on the bell jar to pass through the photoelectric transmitter in sequence. Since the volume between each two adjacent baffles is a known and fixed volume, the actual flow rate can be calculated by recording the time taken for two adjacent baffles to pass through the photoelectric transmitter in succession, and the entire rising height of the bell jar is divided into multiple baffles, and the time taken for each two adjacent baffles to pass through the photoelectric transmitter is measured, which can further improve the measurement accuracy. By comparing the actual flow rate with the reading of the thermal mass flowmeter, the thermal mass flowmeter can be calibrated, with high accuracy, good repeatability, simple and easy operation, and low maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a gas flow device for calibrating a thermal mass flow meter shown in this application. DETAILED DESCRIPTION

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Please refer to Figure 1As shown, the present application discloses a gas flow device for calibrating a thermal mass flowmeter 3, which is used to calibrate the thermal mass flowmeter 3. Specifically, the device includes a gas storage tank 1 for storing gas, a gas control component, a pressure gauge 6 and a thermometer 7, a detection component, and a controller connected to the gas control component, the pressure gauge 6, the thermometer 7 and the detection component. Among them, the gas control component includes a stop valve 2, a flow regulating valve 4 and a three-way valve 5, the stop valve 2, the thermal mass flowmeter 3 to be measured, the flow regulating valve 4, and the three-way valve 5 are connected in series in sequence, and the flow regulating valve 4 is used to adjust the flow of gas in the pipeline to calibrate different flow points. The pressure gauge 6 is connected to the gas control component to detect the pressure of the gas; the thermometer 7 is connected to the pressure gauge 6 to detect the gas temperature to ensure that the entire calibration process is carried out at a reasonable temperature and pressure, thereby improving the calibration accuracy.

[0023] The detection assembly includes a liquid storage tank 9, an air guide tube 8, and a bell jar 10 at least partially located in the liquid of the liquid storage tank 9. Among them, liquid is stored in the liquid storage tank 9, and there is a space between the bell jar 10 and the liquid surface of the liquid storage tank 9. The air guide tube 8 passes through the liquid, one end of which is connected to the gas storage tank 1, and the other end is connected to the space formed between the bell jar 10 and the liquid surface. The space can be changed according to the gas flow provided by the gas storage tank 1, so that the bell jar 10 moves up and down. A photoelectric transmitter 13 is arranged in the height direction of the inner wall of the liquid storage tank 9, and a number of baffles 11 are evenly spaced on the side wall of the bell jar 10. The space between the bell jar 10 and the liquid surface increases with the increase of the gas flow, thereby rising and driving a number of baffles 11 to rise, passing through the photoelectric transmitter 13 in turn, by recording the time taken for each two adjacent baffles 11 to pass through the photoelectric transmitter 13 successively, and based on the known fixed volume between the two adjacent baffles, the actual flow of the pipeline during this period of time can be calculated. The actual flow is compared with the reading of the thermal mass flowmeter 3 to achieve the calibration of the thermal mass flowmeter 3. In this embodiment, the bell jar 10 is a structure with a closed upper part and an open lower part. The liquid in the liquid storage tank 9 is water or low-viscosity oil that is not easy to evaporate. When the bell jar 10 is located in the liquid storage tank 9, the space between the two is a sealed cavity.

[0024] In this embodiment, a scale 12 is fixed on the side wall of the bell jar 10, and a plurality of baffles 11 are evenly spaced and arranged on the scale 12. The height between the two baffles 11 can be confirmed by the scale on the scale 12 to calculate its volume.

[0025] Furthermore, the device also includes a compensation component 16. The liquid storage tank 9 has a top plate, and the top plate has at least two fixed pulleys 15 arranged at intervals and a traction rope 14 arranged around the fixed pulley 15, one end of the traction rope 14 is connected to the compensation component 16, and the other end of the traction rope 14 is connected to the bell jar 10. It should be noted that in this embodiment, the compensation component 16 is a weight-adjustable counterweight, and the buoyancy generated by the liquid in the liquid storage tank 9 on the bell jar 10 can be compensated by setting a counterweight of a reasonable weight, so as to reduce the influence of the buoyancy on the rising height of the bell jar 10, thereby affecting the rising height of the baffle 11, and thus improving the detection accuracy.

[0026] Furthermore, a balancing liquid tank 17 connected to the liquid reservoir 9 is also provided on one side of the liquid reservoir 9, and at least part of the compensation component 16 is located in the balancing liquid tank 17. The purpose of such a setting is that, since the volume of the bell jar 10 in the liquid of the liquid reservoir 9 will change with the airflow, the liquid level of the liquid will also change accordingly. For example, when the bell jar 10 rises, the liquid level in the liquid reservoir 9 will drop accordingly. In order to prevent excessive fluctuations in the liquid level, a liquid level balancing tank is provided to be connected to the liquid reservoir 9 to form a U-shaped tank. When the liquid level in the liquid reservoir 9 drops due to the rise of the bell jar 10, the counterweight moves downward, and its volume immersed in the liquid level balancing tank increases, squeezing the liquid in the liquid level balancing tank into the liquid reservoir 9 to achieve compensation for the liquid level in the liquid reservoir 9, reduce liquid level fluctuations, and thus reduce the impact on the detection gas flow.

[0027] In summary, the calibration process of the thermal mass flowmeter in this embodiment is as follows:

[0028] (1) Before calibration, lower the bell jar to the lowest position and open the end of the three-way valve that is connected to the atmosphere to allow it to communicate with the atmosphere;

[0029] (2) Open the gas tank and the stop valve, allowing the gas in the gas tank to flow into the atmosphere through the stop valve, the thermal mass flow meter to be measured, the flow regulating valve and the three-way valve in sequence;

[0030] (3) Adjust the flow control valve to the required flow rate, run it stably for a period of time, close the end of the three-way valve connected to the atmosphere, and open the end of the three-way valve connected to the air duct. The gas enters the space through the pressure gauge, thermometer, and air duct. The bell jar rises at a uniform speed as the gas flow increases. When the first baffle passes the photoelectric transmitter, an electrical signal is sent to the controller to start the timer. The bell jar continues to rise. When the next baffle passes the photoelectric transmitter, an electrical signal is sent to the controller again to stop the timing. The volume between any two baffles on the bell jar is fixed. The standard flow rate can be calculated by measuring the time it takes for the two baffles to pass through the photoelectric transmitter in succession.

[0031] (4) According to the temperature and pressure at the air inlet of the bell jar, correct the standard flow reading to obtain the flow rate under the standard conditions of the bell jar. Record the flow rate under the standard conditions displayed by the thermal mass flowmeter, and complete the calibration of the thermal mass flowmeter at this flow point by comparing the flow value of the thermal mass flowmeter under the same standard conditions with the standard flow value measured by the bell jar.

[0032] (5) Repeat the above steps to calibrate other flow points of the thermal mass flow meter.

[0033] The above is only a specific implementation of the present application, and any other 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 thermal mass flow meter, characterized in that: include: Gas tanks, used to store gas; A gas control assembly, comprising a stop valve, a flow regulating valve and a three-way valve, wherein the stop valve, the thermal mass flow meter to be measured, the flow regulating valve and the three-way valve are sequentially connected in series; A pressure gauge connected to the gas control assembly and used to detect gas pressure; A thermometer, connected to the pressure gauge, for detecting the gas temperature; The detection component includes a liquid storage tank, an air duct and a bell jar at least partially located in the liquid of the liquid storage tank, there is a space between the bell jar and the liquid surface of the liquid storage tank, the air duct passes through the liquid, one end of which is connected to the gas storage tank, and the other end is connected to the space between the bell jar and the liquid surface, the space can be changed according to the gas flow provided by the gas storage tank to make the bell jar move up and down, a photoelectric transmitter is arranged in the height direction of the inner wall of the liquid storage tank, and a plurality of baffles are evenly spaced on the side wall of the bell jar.

2. A gas flow device for calibrating a thermal mass flowmeter according to claim 1, characterized in that: The device also includes a compensation component; The liquid storage tank has a top plate, and the top plate is provided with at least two fixed pulleys arranged at intervals and a traction rope arranged around the fixed pulley, one end of the traction rope is connected to the compensation component, and the other end of the traction rope is connected to the bell cover.

3. A gas flow device for calibrating a thermal mass flowmeter according to claim 2, characterized in that: A balancing liquid tank connected to the liquid storage tank is also provided on one side of the liquid storage tank, and at least part of the compensation component is located in the balancing liquid tank.

4. A gas flow device for calibrating a thermal mass flowmeter according to claim 1, characterized in that: A scale is fixed on the side wall of the bell jar, and a plurality of baffles are evenly spaced and arranged on the scale.

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