A device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline

Abstract

The application discloses a kind of gas flow rate and concentration measuring devices under high negative pressure environment of pipeline, it is characterized in that, including flow rate detection module and concentration detection module, the flow rate detection module includes pitot tube group and the differential pressure element for detecting total pressure and static pressure data, the pitot tube group includes and is arranged side by side total pressure pipe and static pressure pipe, the total pressure pipe and static pressure pipe are connected to corresponding differential pressure element respectively by pipeline;The concentration detection module includes and is arranged side by side with the total pressure pipe and static pressure pipe intake pipe and outlet pipe, intake pipe and outlet pipe are sequentially connected with first intake filter, air pump assembly and gas sensor module for detecting gas concentration by pipeline between them.The application has the advantages that gas flow rate and concentration can be measured simultaneously under high negative pressure environment, which is beneficial to reduce operation difficulty and equipment cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mine equipment, in particular to a kind of gas flow rate and concentration measuring device in high negative pressure environment of pipeline. BACKGROUND

[0002] In the exploitation of coal mine, gas can be usually exploited, which can be used as fuel and raw material for manufacturing hydrogen and other substances. The gas in the exploitation of coal mine needs to be collected and transported. In the process of pipeline transportation of gas, the gas flow rate and concentration (CH4 concentration, CO concentration, O2 concentration, etc.) in the gas pipeline need to be detected. Since there is a large negative pressure (-50kPa~ -80kPa, relative to standard atmospheric pressure) in the gas pipeline, in order to obtain sufficient detection samples, a gas suction pump is usually used to extract the gas for detection. However, the gas suction process will disturb the gas flow in the gas pipeline, and thus accurate flow rate measurement cannot be performed. Therefore, at present, independent detection equipment is used to detect the gas flow rate and concentration in the gas pipeline by manpower. In this way, the number of detection equipment is increased, which not only increases the cost of equipment and labor, but also increases the operation and control difficulty, so as to ensure the measurement accuracy, and also increases the difficulty of line layout. SUMMARY

[0003] In view of the above problems of the prior art, the present application aims to provide a measuring device capable of simultaneously completing gas flow rate and concentration measurement in high negative pressure environment, which is beneficial to reduce the operation difficulty and equipment cost.

[0004] In order to solve the above technical problems, the present application adopts the following technical scheme:

[0005] A kind of gas flow rate and concentration measuring device in high negative pressure environment of pipeline, it is characterized by including flow rate detection module and concentration detection module, the flow rate detection module includes pitot tube group and the differential pressure element for detecting total pressure and static pressure data, the pitot tube group includes total pressure pipe and static pressure pipe arranged side by side, the total pressure pipe and static pressure pipe are connected to corresponding differential pressure element by pipe respectively;The concentration detection module includes air inlet pipe and air outlet pipe arranged side by side with the total pressure pipe and static pressure pipe, the air inlet pipe and air outlet pipe are sequentially connected with first air inlet filter, gas suction pump assembly and gas sensor module for detecting gas concentration by pipe between them.

[0006] With the above structure, the full pressure pipe, the static pressure pipe, the gas inlet pipe and the gas outlet pipe are arranged side by side, and can be inserted into the gas pipeline together. During measurement, the full pressure and static pressure of the gas flow rate are detected by the full pressure pipe and the static pressure pipe of the Pitot tube group respectively. Since no external interference is required for the gas in the gas pipeline during flow rate measurement, the gas state in the pipeline, including the local gas concentration, is not affected. After completing the flow rate measurement, the gas in the gas pipeline is extracted by the gas extraction pump assembly. Since there are many impurities in the coal mine gas pipeline, the first gas inlet filter is arranged between the gas inlet pipe and the gas extraction pump assembly to filter the impurities, which can avoid the blockage of the gas circuit caused by the impurities, thereby increasing the reliability and prolonging the service life of the equipment. The filtered gas flows through the gas sensor module for gas concentration measurement. The device can reduce the number of detection equipment on the coal mine gas pipeline by combining the flow rate detection module and the concentration detection module, which can reduce the wiring difficulty, and reduce the equipment cost and operation difficulty.

[0007] Further, the concentration detection module further comprises a first electromagnetic valve and a second electromagnetic valve, the first electromagnetic valve is connected between the gas sensor module and the gas outlet pipe, and is used to control the on-off of the gas circuit between the gas sensor module and the gas outlet pipe; the second electromagnetic valve is connected between the first gas inlet filter and the gas extraction pump assembly, and further has an air vent connected to the atmosphere on the second electromagnetic valve, and the second electromagnetic valve is used to switch the communication between the gas extraction pump assembly and the first gas inlet filter or the atmosphere.

[0008] When the concentration measurement is performed, the first electromagnetic valve and the second electromagnetic valve are closed first to cut off the gas circuit between the gas sensor module and the gas outlet pipe, and the gas extraction pump assembly is connected to the atmosphere; the gas extraction pump assembly is started to increase the pressure of the gas sensor module, and after reaching the first set time or pressure, the first electromagnetic valve is opened to connect the gas circuit between the gas sensor module and the gas outlet pipe, release the pressure of the gas sensor module, and keep the pressure higher than the pipeline pressure; after reaching the second set time, the second electromagnetic valve is opened to connect the gas extraction pump assembly and the first gas inlet filter, keep the pressure of the gas sensor module higher than the pipeline pressure, and complete the gas concentration measurement.

[0009] Further, the concentration detection module further comprises a normally closed third electromagnetic valve, one end of the third electromagnetic valve is connected to the gas circuit between the second electromagnetic valve and the first gas inlet filter, and the other end is connected to the atmosphere.

[0010] Since there are many impurities in the gas pipeline, and the concentration detection process needs to extract gas through the air pump assembly, many impurities will be extracted into the air inlet pipe, and finally stay in the air path between the first air inlet filter and the air inlet pipe to cause blockage. On the other hand, the negative pressure in the gas pipeline is much lower than the atmospheric pressure. By adopting the above structure, after the concentration measurement is completed, the air inlet end of the second electromagnetic valve is cut off by closing the second electromagnetic valve, the air outlet end of the first air inlet filter is connected with the atmosphere by opening the third electromagnetic valve, and the outside air is reversely flowed into the gas pipeline through the third electromagnetic valve, the first air inlet filter and the air inlet pipe by using the pressure difference, so as to realize the back blowing of the first air inlet filter and the air inlet pipe and blow the impurities back into the gas pipeline.

[0011] Further, a second air inlet filter is arranged on the air path between the second electromagnetic valve and the air pump assembly.

[0012] Further, the flow rate detection module further comprises a fourth electromagnetic valve and a fifth electromagnetic valve, the fourth electromagnetic valve and the fifth electromagnetic valve are respectively connected between the full pressure pipe and the static pressure pipe and the corresponding differential pressure element, and the fourth electromagnetic valve and the fifth electromagnetic valve further have a communication port connected with each other; the fourth electromagnetic valve is used to switch the differential pressure element to communicate with the corresponding full pressure pipe or the communication port, and the fifth electromagnetic valve is used to switch the differential pressure element to communicate with the corresponding static pressure pipe or the communication port.

[0013] In order to ensure the accuracy of flow rate measurement, the differential pressure element needs to be zeroed before flow rate measurement. By connecting the differential pressure element with the communication port through the fourth electromagnetic valve and the fifth electromagnetic valve, the full pressure detection end and the static pressure detection end are communicated, so that the differential pressure element can be zeroed. When measuring the speed, the full pressure pipe and the static pressure pipe are connected with the corresponding differential pressure element through the fourth electromagnetic valve and the fifth electromagnetic valve, so that the flow rate measurement can be performed.

[0014] Further, the flow rate detection module further comprises a sixth electromagnetic valve and a seventh electromagnetic valve, one end of the sixth electromagnetic valve is connected to the air path between the static pressure pipe and the fifth electromagnetic valve, and the other end is connected with the atmosphere; one end of the seventh electromagnetic valve is connected to the air path between the full pressure pipe and the fourth electromagnetic valve, and the other end is connected with the atmosphere.

[0015] During the flow rate measurement process, although the gas in the gas pipeline is not actively extracted, in order to ensure the accuracy of flow rate measurement, the pipe openings of the full pressure pipe and the static pressure pipe are completely opened, and the impurities in the gas pipeline will also slowly enter under the action of airflow, and finally stay in the full pressure pipe or the static pressure pipe to cause blockage, which affects the accuracy of subsequent flow rate measurement and also affects the service life of the equipment. By using the sixth electromagnetic valve and the seventh electromagnetic valve, the full pressure pipe and the static pressure pipe can be directly connected with the atmosphere, and the outside air can be introduced into the gas pipeline by using the atmospheric pressure to back blow the air inlet pipe.

[0016] Further, one end of the sixth electromagnetic valve, the seventh electromagnetic valve, the second electromagnetic valve and the third electromagnetic valve in communication with the atmosphere is connected with a vacuum filter.

[0017] In this way, dust sucked from the atmosphere can be collected through the vacuum filter, preventing secondary pollution to the air circuit.

[0018] Further, the first air inlet filter and the second air inlet filter each include a bottom plate and a cover plate arranged in mutual engagement, the bottom plate has a positioning groove arranged in recess, a first filter cavity is formed in recess in the middle of the positioning groove, and the bottom plate has a first air port arranged in communication with the first filter cavity; the cover plate has a positioning table formed in protrusion and matched with the positioning groove, the positioning table has a second filter cavity formed in recess in the middle, and the positioning table also has a sealing groove arranged around the second filter cavity, a sealing ring is arranged in the sealing groove, and the cover plate has a second air port arranged in communication with the second filter cavity; the first filter cavity and the second filter cavity each have a gas guide column arranged in protrusion, and the gas guide column is distributed in multiple in the first filter cavity and the second filter cavity; the positioning table is embedded in the positioning groove in cooperation, and a waterproof and air permeable film separating the first filter cavity and the second filter cavity is clamped between the positioning table and the positioning groove.

[0019] During filtration, gas containing impurities and water vapor enters from the first air port or the second air port, is dispersed in the first filter cavity or the second filter cavity under the blockage of the distributed gas guide columns, and passes through the waterproof and air permeable film to the other side, and the impurities and water vapor in the gas are intercepted under the action of the waterproof and air permeable film.

[0020] Further, the positioning groove, the first filter cavity, the positioning table and the second filter cavity are circular, and the gas guide columns are arranged in multiple layers in a ring shape along the axes of the corresponding first filter cavities and second filter cavities.

[0021] Further, the first air port and the second air port are arranged in the radial direction of the first filter cavity and the second filter cavity respectively, and the projections of the first air port and the second air port in the thickness direction of the bottom plate are arranged in mutual misalignment.

[0022] To sum up, the present application has the advantages of being capable of measuring the gas flow rate and concentration simultaneously under high negative pressure environment, being beneficial to reducing the operation difficulty and equipment cost, etc. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 FIG. 1 is a structural schematic diagram of a gas flow rate and concentration measuring device according to an embodiment of the present application.

[0024] Figure 2 FIG. 2 is a schematic diagram of an air circuit structure according to the embodiment 1 of the present application.

[0025] Figure 3 This is a schematic diagram of the internal structure of the rear shell of Example 1.

[0026] Figure 4 This is a schematic diagram of the internal structure of the front cover in Example 1.

[0027] Figure 5 and Figure 6 This is a schematic diagram of the structure of the first and second filters in Example 1.

[0028] Figure 7 This is a schematic diagram of the gas sensor module in Example 1.

[0029] Figure 8 This is a schematic diagram of the air pump assembly in Example 2.

[0030] Figure 9 This is a schematic diagram of the gas path structure in Example 3.

[0031] Figure 10 This is a schematic diagram of the air pump assembly in Example 3. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to an embodiment of the present invention.

[0033] Example 1: As Figure 1 and Figure 2 As shown, a gas flow rate and concentration measuring device under high negative pressure environment in a pipeline includes a rear housing 7 with an opening on one side and a front cover 8. The front cover 8 is located on the side of the rear housing 7 away from the opening and covers the rear housing 7. A flow rate detection module 1 and a concentration detection module 2 are arranged inside the rear housing 7 and the front cover 8. The flow rate detection module 1 includes a Pitot tube assembly 11 and a differential pressure element 12 for detecting total pressure and static pressure data. The Pitot tube assembly 11 includes a total pressure tube and a static pressure tube arranged side by side. The tubes are connected to the corresponding differential pressure elements 12 via pipelines; the concentration detection module 2 includes an inlet pipe 21 and an outlet pipe 22 arranged side by side with the total pressure pipe and the static pressure pipe, and the inlet pipe 21 and the outlet pipe 22 are connected in sequence via pipelines to a first inlet filter 23, a pump assembly 24 and a gas sensor module 25 for detecting gas concentration; in this embodiment, a protective sleeve 17 is installed on the rear housing 7, and the protective sleeve 17 is fitted onto the total pressure pipe, the static pressure pipe, the inlet pipe 21 and the outlet pipe 22.

[0034] The concentration detection module 2 further comprises a first electromagnetic valve 26 and a second electromagnetic valve 27, the first electromagnetic valve 26 is connected between the gas sensor module 25 and the gas outlet pipe 22 and is used to control the opening and closing of the gas path between the gas sensor module 25 and the gas outlet pipe 22; the second electromagnetic valve 27 is connected between the first gas inlet filter 23 and the gas suction pump assembly 24, and the second electromagnetic valve 27 further has a vent port connected to the atmosphere, and the second electromagnetic valve 27 is used to switch the communication between the gas suction pump assembly 24 and the first gas inlet filter 23 or the atmosphere. In order to avoid impurities entering the gas suction pump assembly, a second gas inlet filter 29 is further arranged on the gas path between the second electromagnetic valve 27 and the gas suction pump assembly 24.

[0035] The flow rate detection module 1 further comprises a fourth electromagnetic valve 13 and a fifth electromagnetic valve 14, the fourth electromagnetic valve 13 and the fifth electromagnetic valve 14 are respectively connected between the full pressure pipe and the static pressure pipe and the corresponding differential pressure element 12, and the fourth electromagnetic valve 13 and the fifth electromagnetic valve 14 further have a communication port connected to each other; the fourth electromagnetic valve 13 is used to switch the communication between the differential pressure element 12 and the corresponding full pressure pipe or the communication port, and the fifth electromagnetic valve 14 is used to switch the communication between the differential pressure element 12 and the corresponding static pressure pipe or the communication port.

[0036] During measurement, the full pressure pipe, the static pressure pipe, the gas inlet pipe and the gas outlet pipe arranged side by side are inserted into the gas pipeline together, the gas flow rate detection is performed first, and then the gas concentration detection is performed. Since no external interference is required for the gas in the gas pipeline during flow rate measurement, the gas state in the pipeline, including the local gas concentration, will not be affected. After completing the flow rate measurement, the gas suction pump assembly is started to extract the gas in the gas pipeline. Since there are many impurities in the coal mine gas pipeline, the first gas inlet filter arranged between the gas inlet pipe and the gas suction pump assembly can filter the impurities, which can avoid the blockage of the gas path caused by the impurities, thereby increasing the reliability and prolonging the service life of the equipment. The filtered gas flows through the gas sensor module for gas concentration measurement.

[0037] Specifically, during flow rate measurement, in order to ensure the accuracy of flow rate measurement, the differential pressure element needs to be zeroed before flow rate measurement. The differential pressure element is connected to the communication port through the fourth electromagnetic valve and the fifth electromagnetic valve, so that the full pressure detection end and the static pressure detection end are communicated, and the differential pressure element can be zeroed. During flow rate measurement, the full pressure pipe and the static pressure pipe are respectively connected to the corresponding differential pressure element through the fourth electromagnetic valve and the fifth electromagnetic valve, and flow rate measurement can be performed.

[0038] Since the measuring device of the embodiment is always located outside the gas pipeline during use, and the air extraction pump assembly needs to extract the pipeline gas in a negative pressure state, the leather cup of the air extraction pump assembly bears a large pressure difference (the pressure difference between atmospheric pressure and pipeline negative pressure) on both sides, and it is difficult to start and efficiently extract air under the condition that the power of the air extraction pump assembly meets the national standard and the coal mine industry standard. In order to ensure that the air extraction pump assembly can be reliably started, based on the above structure, when measuring the concentration, the first electromagnetic valve and the second electromagnetic valve can be closed first, the gas path between the gas sensor module and the gas outlet pipe is cut off, the air extraction pump assembly is connected with the atmosphere, the air extraction pump assembly and its air inlet section are all under atmospheric pressure, the pressure difference on both sides of the leather cup is reduced, the air extraction pump assembly is started to extract air, the pressure of the gas sensor module is increased, and after a first set time or pressure is reached, the first electromagnetic valve is opened, the gas path between the gas sensor module and the gas outlet pipe is connected, the pressure of the gas sensor module is released, and the pressure is kept higher than the pipeline pressure; In this way, the air flow rate in the gas sensor module can be stabilized. After a second set time is reached, the second electromagnetic valve is opened, the air extraction pump assembly is connected with the first air inlet filter, the pressure of the gas sensor module is kept higher than the pipeline pressure, which can keep the air flow stable and also blow out the original air in the gas sensor module, so that the gas flows more smoothly through the gas sensor module, and the detection of the gas concentration can be more accurate.

[0039] The first air inlet filter 23 and the second air inlet filter 29 each include a bottom plate 4 and a cover plate 5 that are arranged in a buckling manner, the bottom plate 4 has a positioning groove 41 arranged in a recessed manner, a first filter cavity 42 is formed in a recessed manner in the middle of the positioning groove 41, and the bottom plate 4 has a first gas port arranged in a penetrating manner with the first filter cavity 42; the cover plate 5 has a positioning table 51 arranged in a matching manner with the positioning groove 41, the positioning table 51 has a second filter cavity 52 arranged in a recessed manner in the middle, the positioning table 51 also has a sealing groove 53 arranged around the second filter cavity 52, a sealing ring is arranged in the sealing groove 53, and the cover plate 5 has a second gas port arranged in a penetrating manner with the second filter cavity 52; the first filter cavity 42 and the second filter cavity 52 each have a gas guide column arranged in a protruding manner, and the gas guide column is distributed in a spaced manner in the first filter cavity 42 and the second filter cavity 52; the positioning table 51 is embedded in the positioning groove 41 in a matching manner, and a waterproof and breathable membrane that separates the first filter cavity 42 and the second filter cavity 52 is clamped between the positioning table 51 and the positioning groove 41.

[0040] The positioning groove 41, the first filtering cavity 42, the positioning table 51 and the second filtering cavity 52 are all circular, the gas guide column is arranged in multiple layers along the axis of the corresponding first filtering cavity 42 and second filtering cavity 52 in a ring shape, the first gas port and the second gas port are respectively arranged along the radial direction of the first filtering cavity 42 and the second filtering cavity 52, and the projections of the first gas port and the second gas port on the thickness direction of the bottom plate 4 are arranged in a staggered manner.

[0041] During filtering, the gas containing impurities and water vapor enters from the first gas port or the second gas port, is dispersed in the first filtering cavity or the second filtering cavity under the blockage of the distributed gas guide column, and passes through the waterproof and breathable membrane to the other side. The impurities and water vapor in the gas are intercepted under the action of the waterproof and breathable membrane.

[0042] In this embodiment, as shown in Figure 5 and Figure 6 , the first gas inlet filter 23 and the second gas inlet filter 29 are assembled in a stacked manner, and the cover plate of the first gas inlet filter 23 and the bottom plate of the second gas inlet filter 29 are in an integrated structure.

[0043] Because there are many impurities in the gas pipeline, and the concentration detection process needs to extract gas through the air pump assembly, many impurities will be extracted into the gas inlet pipe, and finally stay in the gas path between the first gas inlet filter and the gas inlet pipe to cause blockage. Therefore, the concentration detection module 2 further includes a normally closed third electromagnetic valve 28, one end of the third electromagnetic valve 28 is connected to the gas path between the second electromagnetic valve 27 and the first gas inlet filter 23, and the other end is communicated with the atmosphere.

[0044] After the concentration measurement is completed, the second electromagnetic valve is closed to cut off the gas inlet end of the second electromagnetic valve, and the third electromagnetic valve is opened to communicate the gas outlet end of the first gas inlet filter with the atmosphere. The pressure difference is used to let the external air flow into the gas pipeline in the reverse direction through the third electromagnetic valve, the first gas inlet filter and the gas inlet pipe, realize the back blowing of the first gas inlet filter and the gas inlet pipe, and blow the impurities back into the gas pipeline.

[0045] During the flow rate measurement process, although the gas in the gas pipeline is not actively extracted, in order to ensure the accuracy of the flow rate measurement, the pipe openings of the total pressure pipe and the static pressure pipe are completely opened, and the impurities in the gas pipeline will also slowly enter under the action of the gas flow, and finally stay in the total pressure pipe or the static pressure pipe to cause blockage, which affects the accuracy of the subsequent flow rate measurement on the one hand, and also affects the service life of the equipment on the other hand.

[0046] To this end, the flow rate detection module 1 further comprises a sixth solenoid valve 15 and a seventh solenoid valve 16, one end of the sixth solenoid valve 15 being connected to the gas path between the static pressure pipe and the fifth solenoid valve 14, and the other end being communicated with the atmosphere; one end of the seventh solenoid valve 16 being connected to the gas path between the full pressure pipe and the fourth solenoid valve 13, and the other end being communicated with the atmosphere. By the sixth solenoid valve and the seventh solenoid valve, the full pressure pipe and the static pressure pipe can be directly connected with the atmosphere, and the atmospheric pressure is used to introduce the outside air into the gas pipeline, and the air inlet pipe is back-flushed.

[0047] In order to avoid the air from the atmosphere carrying dust to cause secondary pollution to the gas path, one end of the sixth solenoid valve 15, the seventh solenoid valve 16, the second solenoid valve 27 and the third solenoid valve 28 communicated with the atmosphere is connected with a vacuum filter 3.

[0048] In this embodiment, as shown in Figure 3 and Figure 4 The first air inlet filter 23, the second air inlet filter 29 and the vacuum filter 3 are all arranged in the rear housing 7, and the first solenoid valve 26, the second solenoid valve 27, the third solenoid valve 28, the fourth solenoid valve, the fifth solenoid valve, the sixth solenoid valve, the air pump assembly 24 and the gas sensor module 25 are all mounted on the back of the rear housing 7.

[0049] As shown in Figure 7 The gas sensor module 25 comprises a rectangular substrate, the substrate having a gas passage hole arranged through in the length direction, and the gas passage hole having a gas nozzle extended at both ends; the substrate has a plurality of sensor mounting seats arranged in the length direction, the bottom of the sensor mounting seat being communicated with the gas passage hole; the sensor mounting seat is respectively mounted with a sensor for detecting the CH4 concentration, the CO concentration and the O2 concentration (not shown in the figure).

[0050] The working measurement process of the gas flow rate and concentration of this embodiment is as follows:

[0051] 1. In the default state, all solenoid valves are not powered on: the first solenoid valve 26 is in the default closed state, the air pump is closed; the third solenoid valve 28 is in the default closed state; the second solenoid valve 27 is in the default state of being communicated with the atmosphere and the air pump assembly; the sixth solenoid valve 15 is in the default closed state; the fourth solenoid valve 13 and the fifth solenoid valve 14 are in the default state of being communicated with each other; the seventh solenoid valve 16 is in the default closed state.

[0052] 2. Power on the equipment, clear the differential pressure element, open the fourth solenoid valve 13 and the fifth solenoid valve 14, start measuring the flow rate, temperature and pressure, and continuously measure for 15 seconds.

[0053] 3. After the flow rate, temperature and pressure measurements are completed, the fourth solenoid valve 13 and the fifth solenoid valve 14 are closed.

[0054] 4. With the atmosphere connected, the air pump assembly is started, the internal pressure of the gas sensor module is detected to increase to ensure that the air pump is started smoothly, and a delay of 200 ms is provided; the first solenoid valve 26 is opened, the gas sensor module releases pressure to be higher than the pipeline pressure, a delay of 200 ms is provided, and the air flow rate in the gas sensor module is stabilized to ensure that the air pump assembly operates stably; the second solenoid valve 27 is opened, and the air inlet of the air pump assembly is switched from the atmosphere to the pipeline. Due to the low pressure in the gas pipeline, the internal pressure of the gas sensor module will continue to decrease, but will be kept higher than the pipeline pressure under the action of the air pump assembly.

[0055] 5. The air pump assembly keeps a stable rate (stable operation) to extract gas from the pipeline, keeps the air pump running continuously for 20 seconds, and measures the gas concentration after the gas concentration is stabilized, thereby ensuring the accuracy of the gas concentration detection, and a delay of 5-10 seconds is provided to take the average value of the measurement results.

[0056] 6. The air pump assembly is closed, and all solenoid valves are closed to complete the measurement.

[0057] In addition, the pipeline can also be cleaned separately, that is, the third solenoid valve 28, the sixth solenoid valve 15 and the seventh solenoid valve 16 are opened in sequence for cleaning.

[0058] Embodiment 2: The main difference between this embodiment and Embodiment 1 is that:

[0059] In Embodiment 1, in order to enable the air pump assembly 24 to start smoothly, the solenoid valves and the gas circuit need to be switched multiple times, and the air drawn in when starting the air pump needs to be reliably discharged through a delay air extraction to ensure that the subsequent extracted gas concentration is stable, resulting in a longer detection time and complex control.

[0060] Therefore, in this embodiment, as shown in Figure 8 the air pump assembly 24 includes a base 61 and a skin bowl air pump 62 mounted on the base 61, the base 61 is provided with a sealing body 63 which tightly wraps the skin bowl air pump 62, the air inlet and air outlet of the skin bowl air pump 62 extend to the outside of the sealing body 63 and are connected with an air inlet filter and a gas sensor module 25 respectively through air pipes, and the inner cavity of the sealing body 63 is connected with the air inlet of the skin bowl air pump 62.

[0061] Since the skin bowl air pump is tightly wrapped in the sealing body, the inner cavity of the sealing body is connected with the air inlet of the skin bowl air pump, and the air inlet of the skin bowl air pump is connected to the inside of the negative pressure pipeline to be detected, so that the skin bowl air pump is in the pressure environment consistent with the inside of the negative pressure pipeline to be detected in the inner cavity of the sealing body. At this time, the pressure inside and outside the skin bowl is consistent, so it can be started more easily. At the same time, since the skin bowl always works in the environment consistent with the pressure inside the negative pressure pipeline to be detected, the output power of the skin bowl air pump is more stable, the air pumping efficiency is higher, the gas detection can be completed faster, and the detection efficiency is improved. In addition, due to the improvement and stability of the suction flow, the detection accuracy is also improved. Further, the skin bowl can also have a longer service life when working in a working environment with a smaller pressure difference for a long time.

[0062] In the embodiment, the sealing body 63 is a sealing cover buckled on the base 61, a sealing ring is arranged between the sealing cover and the base 61, and the sealing cover is fixedly installed on the base 61 by bolts; the sealing cover has two air nozzles penetrating the inner cavity, and the air outlet of the skin bowl air pump 62 is connected with one of the air nozzles, and the air inlet of the skin bowl air pump 62 is located in the sealing cover.

[0063] During air pumping, the air inlet of the skin bowl air pump sucks air from the inner cavity of the sealing cover, thereby further reducing the pressure in the inner cavity. The gas in the negative pressure pipeline to be detected flows into the sealing cover through the air nozzle under the action of the pressure difference, so that the skin bowl air pump as a whole can be ensured to be in a low-pressure environment, the pressure difference acting on the skin bowl is reduced, and the working efficiency of the skin bowl air pump is ensured.

[0064] In specific implementation, the sealing body 63 can also adopt another structure, that is, the sealing body 63 is integrally poured and sealed on the skin bowl air pump 62 and the base 61, the sealing body 63 has a connecting port penetrating the inner cavity, and a three-way pipe is arranged on the air inlet of the skin bowl air pump 62. The connecting port is connected to the three-way pipe through an air pipe. The structure of integral packaging can not only realize reliable sealing of the skin bowl air pump, but also can directly fix the skin bowl air pump on the base.

[0065] Embodiment 3: The main difference between the embodiment and embodiment 2 is that:

[0066] As shown in Figure 9 The concentration detection module 2 further includes a first electromagnetic valve 26 and a second electromagnetic valve 27. The first electromagnetic valve 26 is connected between the gas sensor module 25 and the air outlet pipe 22 and is used to control the opening and closing of the air path between the gas sensor module 25 and the air outlet pipe 22. The second electromagnetic valve 27 is connected between the first air inlet filter 23 and the air pump assembly 24 and is used to control the opening and closing of the air path between the first air inlet filter 23 and the air pump assembly 24.

[0067] AsFigure 10 As shown, the sealing body 63 is a sealing cover buckled on the base 61, a sealing ring is arranged between the sealing cover and the base 61, and the sealing cover is fixedly installed on the base 61 by bolts; the sealing cover has three gas nozzles penetrating the inner cavity, the gas outlet of the leather cup air pump 62 is connected with one of the gas nozzles, and the gas inlet of the leather cup air pump 62 is located in the sealing cover.

[0068] The gas nozzle connected with the gas outlet on the sealing body 63 is connected to the gas sensor module 25 through a pipeline, and the other two gas nozzles are arranged on the two sides of the sealing body 63, one gas nozzle is connected with the second electromagnetic valve 27 through a pipeline, and the other gas nozzle is sequentially connected with the second air inlet filter 29, the third electromagnetic valve 28 and the vacuum filter 3 through a pipeline, and the vacuum filter 3 is the same as the atmosphere.

[0069] The working measurement process of the gas flow rate and concentration in the embodiment is as follows:

[0070] 1. In the default state, all electromagnetic valves are not powered on: the first electromagnetic valve 26 and the second electromagnetic valve 27 are in the closed state by default; the third electromagnetic valve 28 is in the open state by default, and is connected with the atmosphere and the air pump assembly; the others are the same as in embodiment 1, and the measurement steps of the flow rate, temperature and pressure measurement are the same as in embodiment 1, and are not described herein.

[0071] 2. Start the air pump assembly, and the internal pressure of the gas sensor module increases; open the first electromagnetic valve 26 after a delay of 200 ms, the gas sensor module releases the pressure to be higher than the pipeline pressure; open the second electromagnetic valve 27 and the third electromagnetic valve 28 (power on) after a delay of 200 ms, the air inlet of the air pump assembly is switched from the atmosphere to the pipeline, and the internal pressure of the gas sensor module continues to decrease and remains higher than the pipeline pressure.

[0072] 3. Keep the air pump running for 20 seconds, and measure after the gas concentration is stable, delay for 5-10 seconds, and take the average value of the measurement results.

[0073] 4. Turn off the air pump assembly and all electromagnetic valves, and complete the measurement.

[0074] In the embodiment, when the gas circuit for gas concentration detection is cleaned, the second electromagnetic valve 27 is opened, the external air passes through the vacuum filter 3, the third electromagnetic valve 28 and the second air inlet filter 29 under the action of atmospheric pressure, enters the sealing body 63 through one of the gas nozzles, flows from the inner cavity of the sealing body 63, flows out from the other gas nozzle, and then enters the gas pipeline through the second electromagnetic valve 27, the first air inlet filter 23 and the air inlet pipe 21.

[0075] The skin bowl air pump will generate heat in the working process, and the skin bowl air pump will be sealed and wrapped in the sealed body, which will reduce the heat dissipation effect of the skin bowl air pump. In the above back flushing cleaning process, the outside air flows into the sealed body from one side of the sealed body 63, and flows out from the other side of the sealed body, so that the air can fully contact the skin bowl air pump and exchange heat, so that more heat in the sealed body 63 can be taken away, and the heat dissipation of the skin bowl air pump is realized while the back flushing cleaning work is completed.

[0076] The above only describes the preferred embodiments of the present application, and is not limited by the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline, characterized in that, The concentration detection module (2) further comprises a normally closed third electromagnetic valve (28), one end of the third electromagnetic valve (28) is connected to the gas path between the second electromagnetic valve (27) and the first air inlet filter (23), and the other end is connected to the atmosphere.

2. The device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 1, wherein, The second electromagnetic valve (27) and the air suction pump assembly (24) are further provided with a second air inlet filter (29) on the gas path therebetween.

3. The device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 1, wherein, The flow rate detection module (1) further comprises a fourth electromagnetic valve (13) and a fifth electromagnetic valve (14), the fourth electromagnetic valve (13) and the fifth electromagnetic valve (14) are respectively connected between the full pressure pipe and the static pressure pipe and the corresponding differential pressure element (12), the fourth electromagnetic valve (13) and the fifth electromagnetic valve (14) are further provided with a communication port connected to each other; the fourth electromagnetic valve (13) is used for switching the differential pressure element (12) to be connected to the corresponding full pressure pipe or the communication port, and the fifth electromagnetic valve (14) is used for switching the differential pressure element (12) to be connected to the corresponding static pressure pipe or the communication port.

4. The device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 2, wherein, The concentration detection module (2) further comprises a normally closed third electromagnetic valve (28), one end of the third electromagnetic valve (28) is connected to the gas path between the second electromagnetic valve (27) and the first air inlet filter (23), and the other end is connected to the atmosphere. The second electromagnetic valve (27) and the air suction pump assembly (24) are further provided with a second air inlet filter (29) on the gas path therebetween. The flow rate detection module (1) further comprises a fourth electromagnetic valve (13) and a fifth electromagnetic valve (14), the fourth electromagnetic valve (13) and the fifth electromagnetic valve (14) are respectively connected between the full pressure pipe and the static pressure pipe and the corresponding differential pressure element (12), the fourth electromagnetic valve (13) and the fifth electromagnetic valve (14) are further provided with a communication port connected to each other; the fourth electromagnetic valve (13) is used for switching the differential pressure element (12) to be connected to the corresponding full pressure pipe or the communication port, and the fifth electromagnetic valve (14) is used for switching the differential pressure element (12) to be connected to the corresponding static pressure pipe or the communication port.

5. The apparatus for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 4, wherein The flow rate detection module (1) further comprises a sixth electromagnetic valve (15) and a seventh electromagnetic valve (16), one end of the sixth electromagnetic valve (15) is connected to the gas path between the static pressure pipe and the fifth electromagnetic valve (14), and the other end is communicated with the atmosphere; one end of the seventh electromagnetic valve (16) is connected to the gas path between the full pressure pipe and the fourth electromagnetic valve (13), and the other end is communicated with the atmosphere.

6. The apparatus for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 5, wherein The end of the sixth electromagnetic valve (15), the seventh electromagnetic valve (16), the second electromagnetic valve (27) and the third electromagnetic valve (28) communicated with the atmosphere is connected with a vacuum filter (3).

7. The device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 3, wherein, The first air inlet filter (23) and the second air inlet filter (29) each comprise a bottom plate (4) and a cover plate (5) which are buckled with each other, the bottom plate (4) has a positioning groove (41) recessed thereon, a first filter cavity (42) is recessed in the middle of the positioning groove (41), and the bottom plate (4) has a first air port penetrating the first filter cavity (42); the cover plate (5) has a positioning table (51) protruding therefrom and matched with the positioning groove (41), the positioning table (51) has a second filter cavity (52) recessed in the middle thereof, and the positioning table (51) further has a sealing groove (53) surrounding the second filter cavity (52), a sealing ring is arranged in the sealing groove (53), and the cover plate (5) has a second air port penetrating the second filter cavity (52); a gas guide column is protrudingly arranged in each of the first filter cavity (42) and the second filter cavity (52), and a plurality of gas guide columns are distributed at intervals in each of the first filter cavity (42) and the second filter cavity (52); the positioning table (51) is embedded in the positioning groove (41) in cooperation, and a waterproof and breathable membrane separating the first filter cavity (42) and the second filter cavity (52) is clamped therebetween.

8. The device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 7, wherein, The positioning groove (41), the first filter cavity (42), the positioning table (51) and the second filter cavity (52) are circular, and the gas guide columns are arranged in multiple layers in a ring shape along the axes of the first filter cavity (42) and the second filter cavity (52).

9. The device for measuring gas flow rate and concentration in a high negative pressure environment of a pipeline according to claim 8, wherein, The first air port and the second air port are arranged along the radial directions of the first filter cavity (42) and the second filter cavity (52) respectively, and the projections of the first air port and the second air port in the thickness direction of the bottom plate (4) are arranged in a staggered manner.

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