Gas flow rate detection device and detection method

Abstract

This invention discloses a gas flow detection device and method, comprising a gas storage tank with a cavity inside. A second valve is connected to the outside of the gas storage tank, and a first flow meter is connected to the second valve. When the second valve is opened, the output end of the first flow meter communicates with the cavity inside the gas storage tank. A vacuum pump is installed in the gas storage tank, and a third connecting pipe is sealed to the outside of the vacuum pump. The third connecting pipe is connected to a second flow meter. The vacuum pump is connected to both the second flow meter and the cavity inside the gas storage tank. After gas is introduced into the input end of the first flow meter, the gas can flow into the cavity of the gas storage tank through the output end of the first flow meter and the second valve. When the vacuum pump is turned on, the gas in the cavity of the gas storage tank can be discharged through the second flow meter. In this invention, a temperature control device is used to maintain the temperature inside the gas storage tank consistent with the gas source temperature, i.e., controlling the air temperature input to the first and second flow meters, to reduce the influence of temperature on the measurement and increase the accuracy of the measurement.

Description

Technical Field

[0001] This invention relates to the field of gas flow detection technology, and in particular to a gas flow detection device and detection method. Background Technology

[0002] Currently, when testing gas flow rate in the laboratory, it is difficult to collect the gas passing through the flow meter being tested. Therefore, the test can only be performed by comparing the reading with that of a standard flow meter at the input end. Because pressure changes within the closed pipe during gas input cause temperature changes, although flow meters typically have built-in temperature compensation systems, errors still exist. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an air flow detection device and method that are convenient and highly accurate.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] A gas flow detection device includes a gas storage tank with a cavity inside. A valve two is connected to the outside of the gas storage tank, and a first flow meter is connected to the valve two. When the valve two is opened, the output end of the first flow meter is connected to the cavity inside the gas storage tank. A vacuum pump is installed in the gas storage tank, and a connecting pipe three is sealed to the outside of the vacuum pump. The connecting pipe three is connected to a second flow meter. The vacuum pump is connected to the second flow meter and the cavity inside the gas storage tank. After gas is introduced into the input end of the first flow meter, the gas can enter the cavity inside the gas storage tank through the output end of the first flow meter and the valve two. When the vacuum pump is turned on, the gas in the cavity inside the gas storage tank can be discharged through the second flow meter.

[0006] Connecting pipe three is connected to the input end of the second flow meter, and the output end of the second flow meter is connected to the outside.

[0007] The vacuum pump includes an intake channel and an exhaust channel. The intake channel is connected to the cavity of the gas storage tank, and the exhaust channel is connected to the connecting pipe.

[0008] The gas storage tank is also equipped with a one-way valve. The inlet end of the one-way valve is connected to the cavity of the gas storage tank, and the outlet end of the one-way valve is connected to the input end of the second flow meter.

[0009] A valve is sealed at the top of the gas storage tank.

[0010] The gas storage tank is also equipped with a pressure gauge.

[0011] Connecting pipe three is equipped with a plug. When the plug is opened, connecting pipe three is connected to the outside.

[0012] Pressure gauge 2 is installed on connecting pipe 3.

[0013] A method for detecting air flow rate includes an air flow rate detection device and further includes the following steps:

[0014] ① Open valve two, close valve three, and the vacuum pump will shut down;

[0015] ② Once the valve is opened, atmospheric pressure enters the cavity of the gas storage tank, the blockage is opened, and the one-way valve automatically closes.

[0016] ③ Once the valve is closed, the pipe is plugged, the vacuum pump is turned on, and the value displayed on the second flow meter is reset to zero;

[0017] ④ The vacuum pump is turned off, valve two is opened, gas flows through the first flow meter, and the gas enters the cavity of the gas storage tank;

[0018] ⑤ Close valve three and turn on the vacuum pump.

[0019] After the gas introduced by the first flow meter flows into the gas storage tank, the pressure that can be reached in the gas storage tank is greater than the pressure in the connecting pipe.

[0020] The beneficial effects of this invention are:

[0021] The temperature inside the gas storage tank is kept consistent with the gas source temperature by a temperature control device, which controls the air temperature input to the first flow meter and the second flow meter. This reduces the impact of temperature on the measurement, reduces the error caused by the temperature compensation function of the second flow meter, and increases the accuracy of the measurement.

[0022] The gas is stored in a gas storage tank by the first flow meter with a standard reading, and then flows out through the second flow meter. The measurement accuracy of the second flow meter can be compared with that of the first flow meter.

[0023] By selecting the pressure value inside the gas storage tank, the gas flow rate entering the first flow meter is kept consistent with the gas flow rate exiting the second flow meter, thus ensuring the accuracy of the measurement.

[0024] By setting a one-way valve, the pressure inside the gas tank rises to a selected value and then remains constant. Excess pressure is transferred to the connecting pipe and flows out through the second flow meter, thus avoiding safety hazards caused by excessive pressure inside the gas tank. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an embodiment.

[0026] In the diagram: Gas storage tank 1, pressure gauge 11, valve 12, thermometer 13, first flow meter 2, second flow meter 3, vacuum pump 4, intake channel 41, exhaust channel 42, valve 2 5, connecting pipe 1 6, valve 3 61, check valve 7, connecting pipe 2 71, connecting pipe 3 8, plug 81, pressure gauge 2 82. Detailed Implementation

[0027] The technical solution of the present invention will be further described below through embodiments and in conjunction with the accompanying drawings.

[0028] Example 1:

[0029] like Figure 1 As shown, a gas flow detection device includes a gas storage tank 1 with a cavity inside. A valve 2 5 is connected to the left side of the gas storage tank 1, and a first flow meter 2 is connected to the valve 2 5. The input end of the first flow meter 2 is connected to a gas source via a connecting pipe 1 6. The connecting pipe 1 6 is equipped with a valve 3 61 to control the opening and closing of the flow channel. When valve 2 5 is opened, the gas introduced into the connecting pipe 1 6 can enter the cavity inside the gas storage tank 1 through the input end of the first flow meter 2, the output end of the first flow meter 2, and valve 2 5.

[0030] A vacuum pump 4 is installed on the upper right side of the gas storage tank 1. A connecting pipe 3 8 is sealed to the outside of the vacuum pump 4. The vacuum pump 4 includes an intake channel 41 and an exhaust channel 42. The intake channel 41 is inserted into the cavity of the gas storage tank 1 and communicates with the inner cavity of the gas storage tank 1. The exhaust channel 42 is communicated with the inner channel of the connecting pipe 3 8. After the vacuum pump 4 is turned on, the gas in the cavity of the gas storage tank 1 can be transferred to the connecting pipe 3 8 through the vacuum pump 4.

[0031] The connecting pipe 3 is connected to the second flow meter 3. The input end of the second flow meter 3 is connected to the connecting pipe 3 8. The gas introduced into the connecting pipe 1 6 can be air. Therefore, the output end of the second flow meter 3 is directly connected to the outside, and the air is directly discharged through the second flow meter 3.

[0032] Connecting pipe 3 8 is equipped with a plug 81. Opening the plug 81 allows connecting pipe 3 8 to be directly connected to the outside. Connecting pipe 3 8 is also equipped with a pressure gauge 2 82 to detect the internal pressure.

[0033] The gas storage tank 1 is also equipped with a one-way valve 7. One end of the one-way valve 7 is connected to a connecting pipe 2 71. The air inlet end of the one-way valve 7 is connected to the cavity of the gas storage tank 1. The air outlet end of the one-way valve 7 is connected to the connecting pipe 3 8 through the connecting pipe 2 71, which is equivalent to the air outlet end of the one-way valve 7 being connected to the input end of the second flow meter 3.

[0034] The upper end of the gas storage tank 1 is sealed with valve 12. When valve 12 is opened, the external atmospheric pressure can enter the gas storage tank 1, and the inner cavity of the gas storage tank 1 will be naturally filled with air without the need for additional air supply, thus reducing energy consumption.

[0035] The gas storage tank 1 is also equipped with a pressure gauge 11 to detect the pressure in the cavity of the gas storage tank 1. The gas storage tank 1 is also connected to a thermometer 13 to monitor the temperature inside the gas storage tank 1. A corresponding temperature control device is set up to heat or cool the gas storage tank 1 to keep its temperature stable. This is a conventional technology. The temperature control device helps to compensate for the temperature compensation function of the flow meter and increase the accuracy of the measurement.

[0036] Both the first flow meter 2 and the second flow meter 3 are gas flow meters. The condition for both flow meters 2 and 3 to open is that the input pressure of each flow meter is greater than its output pressure, i.e., a pressure difference exists. The first flow meter 2 is a calibrated standard indicated flow meter, and the second flow meter 3 is the flow meter to be tested.

[0037] Example 2:

[0038] A gas flow detection method, using a gas flow detection device as described in Example 1, includes the following steps:

[0039] ① Valve 25 is opened and the first flow meter 2 is closed to disconnect the input end of the first flow meter 2 from the gas storage tank 1, and the vacuum pump 4 is in the off state;

[0040] ② Valve 12 is opened to allow the air in the cavity of the gas tank 1 to be vented to the atmosphere. The pressure inside the cavity of the gas tank 1 is one atmosphere, which is displayed by pressure gauge 11. The plug 81 is opened so that the pressure inside the connecting pipe 3 is also one atmosphere. Therefore, the pressure difference between the two sides of the one-way valve 7 is 0, and the one-way valve 7 is in the automatic closed state. Since the output end of the second flow meter 3 is connected to the atmospheric pressure and the input end of the second flow meter 3 is connected to the connecting pipe 3 8, there is no pressure difference between the two ends of the second flow meter 3, and no air flows inside the second flow meter 3.

[0041] ③ When valve 12 is closed and pipe 81 is closed, vacuum pump 4 is turned on. Vacuum pump 4 transfers the air in the cavity of gas storage tank 1 from the intake channel 41 to the exhaust channel 42, and finally into the connecting pipe 3. At this time, the second flow meter 3 is turned on, the air pressure in the connecting pipe 3 8 increases, and a pressure difference is generated at both ends of the second flow meter 3 until the pressure value is sufficient to allow air to pass through the second flow meter 3. The second flow meter 3 displays the flow value.

[0042] ④ Since vacuum pump 4 cannot completely evacuate the air from the cavity of gas storage tank 1, a pressure value is selected after evacuating the cavity of gas storage tank 1. This value is read from pressure gauge 11. This pressure value can be selected as the pressure value in the cavity of gas storage tank 1 after the maximum limit evacuation of the selected vacuum pump 4, which is convenient for adjustment. At this time, the pressure at the inlet of one-way valve 7 decreases and the pressure at the outlet increases, so one-way valve 7 is in the closed state. When the pressure value in the cavity of gas storage tank 1 reaches the selected pressure value, and the pressure difference on both sides of the second flow meter 3 is insufficient so that the second flow meter 3 does not display a flow value, this step is completed. At this time, the reading of pressure gauge 82 is recorded as P1. This reading shows the critical pressure at which the second flow meter 3 can flow. The flow value of the second flow meter 3 is then cleared to zero.

[0043] ⑤ Vacuum pump 4 is closed, valve 2 5 is opened, and valve 3 61 is opened to allow air to enter the first flow meter 2. The air enters the cavity of the gas storage tank 1, and the pressure in the cavity of the gas storage tank 1 increases. The target pressure value is selected and recorded as P2. This pressure value is greater than the reading recorded by the pressure meter 2 82 (i.e., P2 is greater than P1). Since the difference between the two is the pressure difference between the inlet and outlet of the one-way valve 7, if the pressure in the cavity of the gas storage tank 1 reaches the selected value P2 and valve 2 5 is not closed in time, the pressure in the cavity of the gas storage tank 1 will continue to increase. Therefore, the difference between P1 and P2 is set as the opening pressure value of the one-way valve 7. Once the pressure in the cavity of the gas storage tank 1 exceeds P2, the one-way valve 7 opens, and the air in the cavity of the gas storage tank 1 enters the connecting pipe 3 8, which increases the pressure at the input end of the second flow meter 3, and the second flow meter 3 generates a flow value.

[0044] ⑥ Close valve 361 and record the value of the first flow meter 2 as K1. Turn on vacuum pump 4 to extract the air from the cavity of air tank 1. The air is discharged through the second flow meter 3 until the pressure difference between the two ends of the second flow meter 3 is insufficient to allow air to flow. At this time, the pressure in the connecting pipe 38 is P1, which is the same as the pressure before the first flow meter 2 flows. At this time, the air flow display value of the second flow meter 3 is K2. By comparing K1 and K2, the measurement error of the second flow meter 3 can be verified.

[0045] When repeating the operation a second time, there is no need to open valve 12; simply connect the gas storage tank 1 directly to the first flow meter 2.

[0046] According to the ideal gas law PV=nRT (P is pressure, V is volume, T is steady state, and n and R are constants), it can be seen that as the pressure increases in a closed space, the temperature rises. Although the flow meter has a temperature compensation function, there is still an error. The above operation uses a temperature control device to keep the temperature inside the gas storage tank 1 consistent with the gas source temperature, that is, to control the air temperature input to the first flow meter 2 and the second flow meter 3, so as to reduce the influence of temperature on the measurement.

[0047] When the vacuum pump 4 extracts air from the gas storage tank 1, the pressure and temperature inside the gas storage tank 1 decrease, while the pressure and temperature inside the connecting pipe 3 8 increase. The two cancel each other out the temperature change, so that the temperature change between the air entering the second flow meter 3 and the air entering the first flow meter 2 is reduced, thereby increasing the accuracy of the measurement by the second flow meter 3.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting air flow rate, characterized in that: The method uses a gas flow detection device, which includes a gas storage tank (1) with a cavity inside. A valve (5) is connected to the outside of the gas storage tank (1), and a first flow meter (2) is connected to the valve (5). When the valve (5) is opened, the output end of the first flow meter (2) is connected to the cavity inside the gas storage tank (1). A vacuum pump (4) is installed in the gas storage tank (1), and a connecting pipe (8) is sealed to the outside of the vacuum pump (4). A second flow meter (3) is connected to the connecting pipe (8). The vacuum pump (4) is connected to the second flow meter (3) and the cavity inside the gas storage tank (1) respectively. After gas is introduced into the input end of the first flow meter (2), the gas can be introduced into the cavity of the gas storage tank (1) through the output end of the first flow meter (2) and the valve (5). When the vacuum pump (4) is turned on, the gas in the cavity of the gas storage tank (1) can be discharged through the second flow meter (3). The connecting pipe (8) is connected to the input end of the second flow meter (3), and the output end of the second flow meter (3) is connected to the outside. The gas storage tank (1) is also equipped with a one-way valve (7). The inlet end of the one-way valve (7) is connected to the cavity of the gas storage tank (1), and the outlet end of the one-way valve (7) is connected to the input end of the second flow meter (3). The connecting pipe three (8) is equipped with a plug (81), the plug (81) is opened, and the connecting pipe three (8) is connected to the outside. The gas storage tank (1) is sealed with a valve (12) at its upper end; The input end of the first flow meter (2) is connected to the air source through a connecting pipe (6), and the connecting pipe (6) is equipped with a valve (61) to control the opening and closing of the flow channel; It also includes the following steps: ① The valve 2 (5) is open, the valve 3 (61) is closed, and the vacuum pump (4) is closed; ② When valve one (12) is opened, atmospheric pressure enters the cavity of the gas storage tank (1), the plug (81) is opened, the pressure in the connecting pipe three (8) is the same as the pressure in the cavity of the gas storage tank (1), and the one-way valve (7) is automatically closed. ③ When valve one (12) is closed, the plug (81) is closed, the vacuum pump (4) is turned on, the vacuum pump (4) discharges the air in the cavity of the gas storage tank (1) into the connecting pipe three (8), the second flow meter (3) is turned on, the air pressure in the connecting pipe three (8) increases, and a pressure difference is generated at both ends of the second flow meter (3) until the pressure value is sufficient to allow air to pass through the second flow meter (3), and the second flow meter (3) displays the flow value; ④ The air in the gas storage tank (1) is discharged until the pressure in the cavity of the gas storage tank (1) reaches a selected pressure value. This pressure value is the lowest pressure value reached in the cavity of the gas storage tank (1) after being evacuated by the vacuum pump (4). During the air discharge process in the gas storage tank (1), the one-way valve (7) is in the closed state. The pressure difference on both sides of the second flow meter (3) is insufficient, so the second flow meter (3) has no flow value display. The pressure of the connecting pipe (8) is recorded as P1, and the flow value of the second flow meter (3) is cleared to zero. ⑤ When valve three (61) is opened, vacuum pump (4) is closed, valve two (5) is opened, gas flows through the first flow meter (2), and gas enters the cavity of the gas storage tank (1). The pressure inside the cavity of the gas storage tank (1) reaches P2, where P2 is greater than P1, and the difference between P2 and P1 is the opening pressure value of the one-way valve (7). When the pressure inside the cavity of the gas storage tank (1) exceeds P2, the one-way valve (7) opens, and air in the cavity of the gas storage tank (1) enters the connecting pipe three (8), causing the pressure at the input end of the second flow meter (3) to increase, and the second flow meter (3) flows to generate a flow value. ⑥ Close the valve three (61), record the value of the first flow meter (2) as K1, turn on the vacuum pump (4) to extract the air from the cavity of the gas storage tank (1), and discharge the air through the second flow meter (3) until the pressure difference between the two ends of the second flow meter (3) is insufficient to allow air to flow. At this time, the pressure in the connecting pipe three (8) is P1, and the air flow display value of the second flow meter (3) is K2. By comparing K1 and K2, the measurement error of the second flow meter (3) can be verified.

2. The air flow detection method as described in claim 1, characterized in that: The vacuum pump (4) includes an intake channel (41) and an exhaust channel (42). The intake channel (41) is connected to the cavity of the gas storage tank (1), and the exhaust channel (42) is connected to the connecting pipe (8).

3. The air flow detection method as described in claim 1, characterized in that: The gas storage tank (1) is also equipped with a pressure gauge (11).

4. The gas flow detection method as described in claim 1, characterized in that: The connecting pipe three (8) is equipped with a pressure gauge two (82).

5. The air flow detection method as described in claim 1, characterized in that: After the gas introduced by the first flow meter (2) flows into the gas storage tank (1), the pressure that can be reached in the gas storage tank (1) is greater than the pressure in the connecting pipe (8).

Images