Gas flow device for calibrating gas laminar flow meter

Abstract

The utility model provides a gas flow device for calibrating a gas laminar flow meter. The gas flow device comprises an air compressor, air treatment equipment, a gas storage tank, a first pressure control system, a temperature control loop pipe device, a second pressure control system, a stop valve, a Venturi nozzle, a reversing system, a measured flow meter branch and a weighing branch. The first pressure control system, the temperature control loop pipe device and the second pressure control system are used for maintaining the stability of the pressure and temperature values of the upstream of the Venturi nozzle; after air continuously enters the weighing container, the pressure in the weighing container rises and is spread to the upstream, so that the flow of the pipeline is reduced, the flow control effect is achieved by means of the Venturi nozzle, the flow of the pipeline is not changed along with the downstream pressure change, and then the actual mass flow is accurately calculated through a weighing method. The actual mass flow and the flow display value of the measured gas laminar flow meter are compared, calibration of the gas laminar flow meter can be completed, and the calibration accuracy is improved.

Description

Technical Field

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

[0002] Gas laminar flow meters utilize the characteristics of laminar flow to provide more stable and accurate flow measurement. Gas laminar flow meters play an irreplaceable role in situations where high-precision flow measurement is required, such as scientific research, precision manufacturing and other fields. Unlike turbulent flow meters, gas laminar flow meters are more suitable for measuring fluids with low flow rates and low Reynolds numbers. With the global emphasis on environmental protection and energy conservation, gas laminar flow meters play an important role in monitoring and controlling gas flow. By accurately measuring and controlling gas flow, energy waste and emissions can be reduced, meeting the requirements of sustainable development.

[0003] The working principle of gas laminar flow meter is mainly based on the characteristics of laminar flow, that is, the fluid flows in layers in the pipeline, and the flow layers do not mix with each other. Specifically, when the gas flows through a laminar flow element composed of many small flow channels in a laminar flow state, the pressure difference before and after the laminar flow element is proportional to the average flow velocity of the gas through the laminar flow element, and the volume flow rate and mass flow rate are also proportional to the pressure difference.

[0004] The measurement accuracy of gas laminar flow meters is very important. At present, the calibration of flow meters in the market is generally to connect the calibrated gas flow meter and a standard flow meter of known accuracy in series in the same pipeline, and determine the error of the calibrated flow meter by comparing the measurement results of the two. This calibration method is generally suitable for calibration of larger flow rates. If this method is used to calibrate gas laminar flow meters with low flow rates, the precision is low and the accuracy is not high. Utility Model Content

[0005] The purpose of the utility model is to provide a gas flow device for calibrating a gas laminar flow meter in view of the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0007] The utility model provides a gas flow device for calibrating a gas laminar flow meter, comprising: an air compressor for generating high-pressure air;

[0008] Air handling equipment, which is used to purify the air;

[0009] Air tanks, which are used to store compressed air;

[0010] A first pressure control system, which is used to control the air pressure entering the temperature control loop pipe device to remain constant;

[0011] A temperature-controlled loop pipe device, which is used to control the temperature of the air passing through its loop pipe to remain constant;

[0012] A second pressure control system, which is used to control the air pressure entering the venturi nozzle to remain constant;

[0013] Stop valve, which is used to control the opening and closing of the pipeline;

[0014] Venturi nozzles, which are used to control pipeline flow without changing downstream pressure;

[0015] The air compressor, air handling equipment, air storage tank, first pressure control system, temperature control loop pipe device, second pressure control system, stop valve, and venturi nozzle are connected in sequence via pipelines;

[0016] A reversing system, which is used to control the switching of the outlet of the venturi nozzle to be connected to the branch of the measured flow meter or to the weighing branch;

[0017] A timer, which is used to calculate the duration of the connection between the venturi nozzle outlet and the weighing branch;

[0018] The measured flow meter branch includes a measured gas laminar flow meter, a regulating valve and a muffler which are sequentially connected in series through a pipeline, wherein the regulating valve is used to adjust the pressure of the pipeline where the measured gas laminar flow meter is located, and the muffler is used to reduce the noise generated when the pipeline is running;

[0019] The weighing branch comprises a weighing container disengaging and docking mechanism, a weighing container, a weighing device and a lifting drive mechanism. The weighing container disengaging and docking mechanism is used to control the disengagement and docking of the weighing container and the pipeline. The weighing container is used to store gas. The weighing device is used to weigh the weighing container. The lifting drive mechanism is used to drive the weighing container to rise and fall. After the weighing container falls on the weighing device, the lifting drive mechanism is separated from the weighing container.

[0020] Optionally, the outlet pressure of the air compressor reaches 14 MPa.

[0021] Optionally, the oil content of the air purified by the air treatment equipment is not higher than 5 ppm, the dew point is not higher than -40°C, and the size of the solid particles is not greater than 0.1 μm.

[0022] Optionally, the pressure in the gas storage tank is controlled at 7MPa; and the pressure in the loop pipe in the temperature control loop pipe device is controlled at 6MPa.

[0023] Optionally, the reversing system includes a first ball valve, a second ball valve and a pneumatic control device, wherein the first ball valve and the second ball valve are linked and controlled by the pneumatic control device, and the second ball valve is closed while the first ball valve is opened, and the second ball valve is opened while the first ball valve is closed.

[0024] The beneficial effects of the utility model include:

[0025] The utility model utilizes the critical flow principle. When the gas passes through the Venturi nozzle, it reaches a sonic flow state at the nozzle throat. At this time, the gas flow rate is only related to the pressure and temperature upstream of the nozzle, and has nothing to do with the pressure change downstream. The stability of the pressure and temperature values ​​upstream of the Venturi nozzle is maintained by the first pressure control system, the temperature control loop pipe device and the second pressure control system; when the air continuously enters the weighing container, the pressure in the weighing container increases, which will propagate upstream, causing the pipeline flow rate to decrease. With the help of the Venturi nozzle, the flow control effect is played, so that the pipeline flow rate is not affected by the downstream pressure change, and then the actual mass flow rate is accurately calculated by the weighing method. By comparing the actual mass flow rate and the flow display value of the measured gas laminar flow meter, the calibration of the gas laminar flow meter can be completed, and the accuracy of the calibration is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A structural schematic diagram of an implementation mode of the utility model is shown.

[0028] Reference numerals:

[0029] 11-air compressor; 12-air handling equipment; 13-air storage tank; 14-first pressure control system; 15-temperature control loop pipe device; 16-second pressure control system; 17-stop valve; 18-Venturi nozzle; 21-first ball valve; 22-measured gas laminar flow meter; 23-regulating valve; 24-muffler; 31-second ball valve; 32-weighing container disconnection and docking mechanism; 33-weighing container; 34-weighing device; 35-lifting drive mechanism. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0033] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Figure 1 FIG. 1 shows a schematic diagram of the structure of a gas flow device for calibrating a gas laminar flow meter provided by an embodiment of the utility model. Figure 1 As shown, the gas flow device for calibrating a gas laminar flow meter provided by the utility model comprises:

[0036] An air compressor 11, which is used to generate high-pressure air;

[0037] Air treatment equipment 12, which is used to purify the air;

[0038] An air storage tank 13, which is used to store compressed air;

[0039] A first pressure control system 14, which is used to control the air pressure entering the temperature control loop pipe device 15 to remain constant;

[0040] A temperature control loop pipe device 15, which is used to control the temperature of the air passing through its loop pipe to remain constant;

[0041] A second pressure control system 16, which is used to control the air pressure entering the venturi nozzle 18 to remain constant;

[0042] A stop valve 17, which is used to control the opening and closing of the pipeline;

[0043] A venturi nozzle 18, which is used to control the flow rate of the pipeline without changing the downstream pressure;

[0044] The air compressor 11, the air treatment equipment 12, the air storage tank 13, the first pressure control system 14, the temperature control loop pipe device 15, the second pressure control system 16, the stop valve 17, and the venturi nozzle 18 are connected in sequence through pipelines;

[0045] A reversing system, which is used to control the switching of the outlet of the venturi nozzle to be connected to the branch of the measured flow meter or to the weighing branch;

[0046] A timer, which is used to calculate the duration of the connection between the venturi nozzle outlet and the weighing branch;

[0047] The measured flow meter branch includes a measured gas laminar flow meter 22, a regulating valve 23 and a muffler 24 which are connected in series through a pipeline. The regulating valve 23 is used to adjust the pressure of the pipeline where the measured gas laminar flow meter is located, and the muffler 24 is used to reduce the noise generated when the pipeline is running;

[0048] The weighing branch includes a weighing container disengaging and docking mechanism 32, a weighing container 33, a weighing device 34 and a lifting drive mechanism 35. The weighing container disengaging and docking mechanism 32 is used to control the disengagement and docking of the weighing container 33 and the pipeline. The weighing container 33 is used to store gas. The weighing device 34 is used to weigh the weighing container 33. The lifting drive mechanism 35 is used to drive the weighing container 33 to rise and fall. After the weighing container 33 falls on the weighing device 34, the lifting drive mechanism 35 is separated from the weighing container 33.

[0049] In the gas flow device for calibrating the gas laminar flow meter provided by the utility model, the critical flow principle is used. When the gas passes through the Venturi nozzle, it reaches a sonic flow state at the nozzle throat. At this time, the gas flow is only related to the pressure and temperature upstream of the nozzle, and has nothing to do with the pressure change downstream. The stability of the pressure and temperature values ​​upstream of the Venturi nozzle is maintained by the first pressure control system, the temperature control loop pipe device and the second pressure control system; when the air continuously enters the weighing container, the pressure in the weighing container increases, which will propagate upstream, causing the pipeline flow to decrease. With the help of the Venturi nozzle, the flow control effect is played, so that the pipeline flow is not affected by the downstream pressure change, and then the actual mass flow is accurately calculated by the weighing method. By comparing the actual mass flow and the flow display value of the measured gas laminar flow meter, the calibration of the gas laminar flow meter can be completed, and the accuracy of the calibration is improved.

[0050] Optionally, the outlet pressure of the air compressor 11 reaches 14 MPa.

[0051] Optionally, the oil content of the air purified by the air treatment device 12 is not higher than 5 ppm, the dew point is not higher than -40°C, and the size of the solid particles is not greater than 0.1 μm.

[0052] Optionally, the pressure in the gas storage tank 13 is controlled at 7 MPa; and the pressure in the loop pipe of the temperature control loop pipe device 15 is controlled at 6 MPa.

[0053] Optionally, the reversing system includes a first ball valve 21, a second ball valve 31 and a pneumatic control device. The first ball valve 21 and the second ball valve 31 are linked and controlled by the pneumatic control device. The second ball valve 31 is closed when the first ball valve 21 is opened, and the second ball valve 31 is opened when the first ball valve 21 is closed.

[0054] Optionally, the temperature control loop pipe device 15 includes a loop pipe, a heating / cooling device, an insulation layer and a temperature sensor. The heating / cooling device is used to control the temperature of the loop pipe, the insulation layer is used to insulate the loop pipe, and the temperature sensor is used to detect the air temperature in the loop pipe in real time. Before calibration, the air temperature in the loop pipe is controlled to be equal and stable to ensure that the temperature of the gas remains unchanged during the calibration process.

[0055] Optionally, the weighing container disconnection and docking mechanism 32 is composed of a set of start ball valves and sealing mechanisms, so that the weighing container is disconnected from the pipeline before and after calibration for weighing. The weighing container is a sealed high-pressure resistant container, and the weighing container and the weighing device are pre-calibrated.

[0056] The working process of the gas flow device for calibrating the gas laminar flow meter is as follows:

[0057] (1) Status of the device before calibration: the stop valve 17 is closed, the regulating valve 23 is open, the reversing system leads to the pipeline where the laminar flow meter of the measured gas is located, that is, the first ball valve 21 is open, the second ball valve 31 is closed, and the weighing container 33 is disconnected from the pipeline and supported by the lifting drive mechanism 35.

[0058] (2) Operate the lifting drive mechanism 35 to place the weighing container 33 on the weighing device 34 for weighing, record the initial value m0 of the weighing device 34, and then the lifting drive mechanism 35 props up the weighing container 33 and connects it to the pipeline.

[0059] (3) Turn on the air compressor 11, and the air passes through the air handling device 12 and enters the air storage tank 13 and the temperature control loop pipe device 15, and stabilizes for a period of time so that the air temperature in the loop pipe reaches the preset temperature and the temperature is uniform.

[0060] (4) Slowly open the stop valve 17, and the isothermal air passes through the first pressure control system 14, the temperature control loop pipe device 15, the second pressure control system 16, the stop valve 17, the Venturi nozzle 18, the first ball valve 21, the measured gas laminar flow meter 22, the regulating valve 23 and the muffler 24 in sequence. Due to the control of the first pressure control system 14 and the second pressure control system 16, the air pressure in the pipeline is the required pressure and remains unchanged. Due to the control of the temperature control loop pipe device 15, the temperature of the air flowing out of its outlet remains unchanged. Due to the control of the Venturi nozzle 18, the pipeline flow remains unchanged (not affected by the change of its downstream pressure).

[0061] (5) After the gas flow is stable, record the flow value displayed by the laminar flow meter 22 of the gas being measured. Start the reversing system, close the first ball valve 21, open the second ball valve 31, let the gas flow to the weighing container 33, and start the timer at the same time.

[0062] (6) When the pressure downstream of the Venturi nozzle 18 is about to rise to a critical pressure ratio relative to the pressure upstream thereof, the reversing system is started, the second ball valve 31 is closed, the first ball valve 21 is opened, and the gas flows to the laminar flow meter 22 of the gas to be measured, and the timer is stopped at the same time.

[0063] (7) Use the weighing container disconnecting and docking mechanism to disconnect the weighing container 33 from the pipeline, and place it on the weighing device 34 for weighing to obtain the final value m1 of the weighing device 34.

[0064] (8) The actual mass flow rate of the measured gas laminar flow meter is obtained according to the following formula:

[0065]

[0066] Where: q m —The actual mass flow rate of the laminar flow meter of the measured gas;

[0067] m0—initial value of weighing device;

[0068] m1—final value of weighing device;

[0069] t—The time measured by the timer.

[0070] (9) Compare the actual mass flow rate of the measured gas laminar flow meter with the flow rate display value to complete the calibration of the gas laminar flow meter.

[0071] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A gas flow device for calibrating a gas laminar flow meter, characterized in that: include: An air compressor, which is used to generate high-pressure air; Air handling equipment, which is used to purify the air; Air tanks, which are used to store compressed air; A first pressure control system, which is used to control the air pressure entering the temperature control loop pipe device to remain constant; A temperature-controlled loop pipe device, which is used to control the temperature of the air passing through its loop pipe to remain constant; A second pressure control system, which is used to control the air pressure entering the venturi nozzle to remain constant; Stop valve, which is used to control the opening and closing of the pipeline; Venturi nozzles, which are used to control pipeline flow without changing downstream pressure; The air compressor, air handling equipment, air storage tank, first pressure control system, temperature control loop pipe device, second pressure control system, stop valve, and venturi nozzle are connected in sequence via pipelines; A reversing system, which is used to control the switching of the outlet of the venturi nozzle to be connected to the branch of the measured flow meter or to the weighing branch; A timer, which is used to calculate the duration of the connection between the venturi nozzle outlet and the weighing branch; The measured flow meter branch includes a measured gas laminar flow meter, a regulating valve and a muffler which are sequentially connected in series through a pipeline, wherein the regulating valve is used to adjust the pressure of the pipeline where the measured gas laminar flow meter is located, and the muffler is used to reduce the noise generated when the pipeline is running; The weighing branch comprises a weighing container disengaging and docking mechanism, a weighing container, a weighing device and a lifting drive mechanism. The weighing container disengaging and docking mechanism is used to control the disengagement and docking of the weighing container and the pipeline. The weighing container is used to store gas. The weighing device is used to weigh the weighing container. The lifting drive mechanism is used to drive the weighing container to rise and fall. After the weighing container falls on the weighing device, the lifting drive mechanism is separated from the weighing container.

2. The gas flow device for calibrating a gas laminar flow meter according to claim 1, characterized in that: The outlet pressure of the air compressor reaches 14MPa.

3. The gas flow device for calibrating a gas laminar flow meter according to claim 1, characterized in that: The oil content of the air purified by the air treatment equipment is not higher than 5ppm, the dew point is not higher than -40°C, and the size of the solid particles is not greater than 0.1μm.

4. The gas flow device for calibrating a gas laminar flow meter according to claim 1, characterized in that: The pressure in the gas storage tank is controlled at 7MPa; the pressure in the loop pipe in the temperature control loop pipe device is controlled at 6MPa.

5. The gas flow device for calibrating a gas laminar flow meter according to claim 1, characterized in that: The reversing system includes a first ball valve, a second ball valve and a pneumatic control device. The first ball valve and the second ball valve are linked and controlled by the pneumatic control device. When the first ball valve is opened, the second ball valve is closed. When the first ball valve is closed, the second ball valve is opened.

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