Smoke dust direct-reading measuring instrument calibration system

Abstract

The invention relates to a smoke dust direct-reading measuring instrument calibration system which comprises a dust generation device and a wind tunnel, the wind tunnel comprises an air inlet section, a contraction section, a first test cavity, a diffusion section, a straight pipe section, a second test cavity, a dust removal section and a first fan which are communicated in sequence, and a first test opening is formed in the surface of the first test cavity; a second test port is formed in the surface of the second test cavity; the dust generating device comprises a dust feeder and a dust diffusion assembly arranged between the air inlet section and the contraction section, the dust diffusion assembly comprises a first rectifying pipe, a conical pipe, a second rectifying pipe and a jet pipe, the first rectifying pipe, the conical pipe and the second rectifying pipe are communicated in the air direction, and the jet pipe is arranged in the first rectifying pipe in a sleeved mode in the axial direction. The side opening of the jet pipe is communicated with the dust feeder, and the air guide pipe is used for blowing out dust through compressed airflow and improving the diffusion efficiency and concentration uniformity of the dust, so that the wind tunnel simulates the smoke environment in different test cavities, and the calibration error is reduced through more complete environment simulation.

Description

Technical Field

[0001] The present application belongs to the technical field of smoke environment detection, and in particular relates to a calibration system for a smoke direct-reading measuring instrument. Background Art

[0002] The smoke direct-reading measuring instrument is a device suitable for monitoring the content of fine particulate matter in the flue gas emitted by the coal chemical industry. Its monitoring results are used to reflect whether the emitted flue gas meets the standards. In order to meet the ultra-low emission and fine particulate matter monitoring requirements of the coal chemical industry, the calibration equipment and calibration methods of the smoke direct-reading measuring instrument are studied to meet the calibration standards of the smoke direct-reading measuring instrument, which is the core to ensure the application and development of the smoke direct-reading measuring instrument. At present, the calibration technology for the smoke direct-reading measuring instrument is to simulate the test environment of the smoke direct-reading measuring instrument through a dust generating device and a wind tunnel equipment. This technology simulates the situation where the exhaust flue gas contains different concentrations of smoke particles by generating dust in a wind field with a controllable flow rate, so as to obtain the working state of the smoke direct-reading measuring instrument in the simulated smoke environment, thereby achieving the calibration purpose. To this end, relevant fields have carried out research on dust environment simulation and measurement equipment.

[0003] In the prior art, a Chinese invention with publication number CN103234573B discloses a dust environment simulation device, which includes a dust generating device, a wind tunnel, a dust collector and a fan, wherein the powder outlet of the dust generating device is arranged at the front end of the air inlet section of the wind tunnel, the dust collector is arranged at the end of the wind tunnel, the fan is arranged at the exhaust outlet of the dust collector, the middle section of the wind tunnel is arranged as a test section dedicated to setting a smoke direct-reading measuring instrument to be calibrated, the dust generating device includes a dust feed hopper, a stirring output chamber, a belt conveyor, a dispersing feeder and a dust outlet pipe; the dust feed hopper is installed at the upper port of the stirring output chamber, a discharge port is provided on the bottom plate of the stirring output chamber, a through port connected to the discharge port is provided on the side wall of the stirring output chamber, the conveyor belt surface of the belt conveyor is arranged below the discharge port, the dispersing feeder is connected to the through port to raise the dust on the conveyor belt surface, the dust outlet pipe is connected to the dispersing feeder, and the dust outlet pipe is connected to the compressed air inlet. Although the above-mentioned dust generating device can emit dust and cooperate with the wind field generated by the fan in the wind tunnel to disperse the dust in the wind tunnel to simulate a certain concentration of smoke and dust environment, the dust environment simulation equipment has the following problems: First, since the dust generating device is arranged outside the discharge port and the dust generating distance is limited, the emitted dust relies too much on the wind tunnel for uniform diffusion. When it is necessary to simulate the dust environment under low wind speed conditions, the distance from the dust emitted by the dust generating device to the test section is relatively far, which can easily lead to uneven gas-solid distribution in the two-phase flow, causing the concentration test of the smoke direct-reading tester to be prone to errors; Second, since the test section is located at the position where the gas-solid two-phase flow state of the wind tunnel is the most stable, as the gap of the dust collector gradually decreases, the wind speed change speed and range decrease, resulting in the attenuation of the range of wind speed simulation in the test section, causing errors in the high wind speed test of the smoke direct-reading tester. Summary of the invention

[0004] Based on the above-mentioned background technology needs, the present application provides a smoke direct-reading measuring instrument calibration system, which can provide a more complete and realistic smoke environment for the calibration of the smoke direct-reading tester, accurately calibrate the concentration indication and wind speed indication of the smoke direct-reading tester, and reduce the occurrence of test errors.

[0005] In order to achieve the above purpose, the technical solution of this application is: A smoke direct-reading measuring instrument calibration system comprises a dust generating device and a wind tunnel, wherein the wind tunnel comprises an air inlet section, a contraction section, a first test chamber, a diffusion section, a straight pipe section, a second test chamber, a dust removal section and a first fan which are sequentially connected, wherein the surface of the first test chamber can be opened to be provided with a first test port, and the surface of the second test chamber can be opened to be provided with a second test port; the dust generating device comprises a dust feeder and a dust diffusion assembly which is arranged at the junction of the air inlet section and the contraction section, wherein the dust diffusion assembly comprises a first rectifier tube, a conical tube which are sequentially connected along the wind direction of the wind tunnel, and a second rectifier tube which is arranged at the junction of the air inlet section and the contraction section. and a second rectifier tube, the small mouth of the conical tube is connected to the first rectifier tube, the large mouth of the conical tube is connected to the second rectifier tube, an air guide tube and a dust guide tube are arranged on the side of the first rectifier tube, one end of the dust guide tube extends beyond the contraction section and is connected to the dust feeder, a jet tube is axially sleeved in the first rectifier tube, the air inlet of the jet tube is connected to the air guide tube, the air guide tube is used to pass compressed air into the jet tube, and a dust suction port is arranged on the side of the jet tube, the dust suction port is connected to the dust guide tube.

[0006] Preferably, the front lip of the air inlet of the air inlet section is arc-shaped, and a honeycomb rectifier plate, a plurality of rectifier nets and a static pressure box are sequentially arranged along the wind direction of the wind tunnel between the air inlet of the air inlet section and the contraction section.

[0007] Preferably, a first fixed rib is provided between the first rectifier tube and the inner wall of the contraction section, the first rectifier tube is fixed to the axis of the contraction section through the first fixed rib, the windward surface of the first fixed rib is wedge-shaped or arc-shaped, and the first fixed rib is provided with a through hole passing through the contraction section, and the air guide tube and the dust guide tube are located in the through hole.

[0008] Preferably, the internal space of the jet tube is convergent at one end adjacent to the air duct in a direction away from the air duct, and is divergent at the other end in a direction away from the air duct.

[0009] Preferably, along the axial direction of the jet tube, a back-blowing port is provided on the side surface of the jet tube between the diffused end of the jet tube and the dust suction port, and the back-blowing port is inclined toward a direction close to the dust suction port.

[0010] Preferably, the inclination angle of the back-blowing port is greater than 0° and less than or equal to 45°.

[0011] Preferably, the dust diffusion assembly further includes a second fan, the second fan is an axial flow fan, and an air outlet of the second fan is connected to an air inlet of the first rectifier tube.

[0012] Preferably, a conical breaker body is sleeved in the conical tube, and the conical breaker body, the conical tube and the second rectifying tube respectively form a first diffusion space and a second diffusion space in a direction away from the jet tube, and the first diffusion space is connected to the second diffusion space.

[0013] Preferably, one end of the conical breaker body adjacent to the first rectifier tube is conical, and its vertex angle is greater than the vertex angle of the conical tube.

[0014] Preferably, a plurality of second fixed ribs are provided at annular intervals between the conical breaker body and the conical tube, the conical breaker body is connected to the conical tube via the second fixed ribs, and the windward surface of the second fixed ribs is wedge-shaped or arc-shaped.

[0015] By adopting the above technical solution, compared with the prior art, the present application has at least the following beneficial effects: First, the smoke direct-reading measuring instrument calibration system can be used to simulate smoke environments of different states between relatively high concentration and low concentration, and the smoke direct-reading measuring instrument to be calibrated can be tested and calibrated, so that the smoke direct-reading measuring instrument can be tested for smoke concentration indication error in an environment with a large smoke concentration variation range and an environment with a stable concentration, so as to improve the authenticity and integrity of the smoke environment simulation; the smoke direct-reading measuring instrument can also be tested for wind speed indication error and reading response speed in an environment with a large wind speed variation range and high complexity of the airflow field and an environment with controllable wind speed variation and stable airflow field. Compared with the prior art, a more comprehensive and complete test environment can be provided in the calibration operation of the smoke direct-reading tester, avoiding the problem of large test errors caused by insufficient environmental simulation range; 2. The dust generating device in the present system not only has the function of increasing the ejection velocity and kinetic energy of the dust by cooperating with the diffusion structure through the jet tube that ejects high-speed and high-pressure airflow, but also has the function of pre-diffusion of the dust. After the dust is initially diffused in the diffusion component, it is diffused for the second time through the convergence-diffusion structure of the wind tunnel, which further improves the diffusion efficiency and diffusion range of the dust, making the discharge of the dust more uniform and smooth. Compared with the prior art, it can simulate a smoke environment with more stable concentration, more complete diffusion and more uniform mixing in the second test chamber, which helps to improve the accuracy of the indication of the smoke direct-reading measuring instrument and make the calibration work meet higher verification standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the smoke direct-reading measuring instrument calibration system in the embodiment.

[0017] Figure 2 Schematic diagram of the internal structure of the dust diffusion component in the embodiment.

[0018] Figure 3 A is a partial enlarged view of the contraction section in the embodiment.

[0019] Figure 4 FIG. B is a partial enlarged view of the dust diffusion component in the embodiment.

[0020] Figure 5 It is a partial cross-sectional view CC of the dust diffusion component and a partial schematic view of the second fixed rib in the embodiment.

[0021] Figure 6 Schematic diagram of the structure of the air inlet section in the embodiment.

[0022] In the figure: wind tunnel 10, air inlet section 11, arc-shaped air inlet 111, honeycomb rectifier plate 112, rectifier net 113, static pressure box 114, contraction section 12, first fixed rib 121, through hole 1211, first test chamber 13, first test port 131, diffusion section 14, straight pipe section 15, second test chamber 16, second test port 161, dust removal section 17, first fan 18, bracket 19, dust generating device 20, dust feeder 21, dust Diffuser assembly 22, first rectifier tube 221, conical tube 222, second fixed rib 2221, second rectifier tube 223, air guide tube 224, pressure regulating valve 2241, dust guide tube 225, jet tube 226, dust suction port 2261, backblowing port 2262, second fan 227, conical breaking fluid 228, spoiler paddle 229, air compressor 23, wind speed controller 30, smoke direct reading meter 40, wind speed measuring probe 41. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The technical solution of the present application will be further described below in conjunction with the drawings of the embodiments of the present application, and the present application is not limited to the following specific implementation methods.

[0024] It should be understood that the same or similar reference numerals in the drawings of the embodiments correspond to the same or similar components. In the description of the present application, it should be understood that if there are terms such as "upper", "lower", "inner", "outer", "left", "right", "front", "rear", "top", "bottom" and the like indicating directions or positional relationships based on the orientations or positional relationships shown in the drawings, it is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the structure or component referred to must have a specific orientation, be constructed and operated in a specific orientation, therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on the present patent, and for those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0025] The following is combined with Figure 1 To Attachment Figure 6And specific embodiments further describe the present application in detail.

[0026] The present application discloses a smoke direct-reading measuring instrument calibration system (hereinafter referred to as the system), which includes a dust generating device 20 for generating smoke and a wind tunnel 10 for simulating a smoke test environment, wherein the wind tunnel 10 includes an air inlet section 11, a contraction section 12, a first test chamber 13, a diffusion section 14, a straight pipe section 15, a second test chamber 16, a dust removal section 17 and a first fan 18, which are arranged on a plurality of brackets 19 and are connected in sequence at the tail and the head, and each pipe section forms a complete air flow channel, so that the air flow enters from the inlet of the air inlet section 11 and is discharged through the exhaust port of the first fan 18; the first test chamber 13 and the first test chamber 13 are connected in sequence. The second test chamber 16 is a straight tube structure, and the surface thereof can be opened or closed and provided with a first test port 131 and a second test port 161, respectively. The opening sizes of the first test port 131 and the second test port 161 can meet the requirements of the smoke direct reading measuring instrument 40, the whole of the standard anemometer or its probe corresponding to the test item (such as the wind speed measuring probe 41) or the filter membrane sampler extending into the wind tunnel 10. Specifically, the first test port 131 is located at one end of the first test chamber 13 close to the diffusion section 14, and the second test port 161 is arranged in the middle and rear section of the second test chamber 16 along the wind direction of the wind tunnel 10; the dust generating device 2 0 includes a dust feeder 21 and a dust diffusion assembly 22 arranged at the junction of the air inlet section 11 and the contraction section 12, the dust feeder 21 at least includes a container for storing simulated smoke such as coal powder, ISO-AⅠ dust, ISO-A2 dust, etc., the container is provided with a discharge port with a negative pressure discharge valve, and negative pressure can be generated at the discharge port to make the negative pressure discharge valve form a corresponding discharge opening to achieve quantitative discharge of dust (since the negative pressure discharge valve is not a necessary feature for solving the technical problem of the present application, its structure is omitted in the text and drawings of the present application); the dust diffusion assembly 22 includes a The first rectifier tube 221, the tapered tube 222 and the second rectifier tube 223 are connected in order in wind direction, wherein the first rectifier tube 221 and the second rectifier tube 223 are straight tubes with different inner diameter values, which are used to make the incoming airflow flow in a straight line; the tapered tube 222 is a tube section with a tapered internal space, and the opening area of ​​one end thereof is smaller than the opening area of ​​the other end to form a diffusion structure, so that the wind field flowing in from its small opening can be rapidly diffused, the small opening of the tapered tube 222 is connected to one end of the first rectifier tube 221 through a flange butt connection, and the large opening of the tapered tube 222 is connected to the second rectifier tube 223 through a flange butt connection;An air guide 224 and a dust guide 225 are sequentially arranged on the side of the first rectifying tube 221 along the wind direction in the wind tunnel 10. The dust guide 225 is connected to the discharge port of the dust diffusion assembly 22. A jet tube 226 is sleeved axially in the first rectifying tube 221. The air inlet of the jet tube 226 is sealed and connected to the air guide 224. The other end of the air guide 224 extends outside the wind tunnel 10 and is connected to an air compressor 23. The air compressor 23 is used to collect and compress air. The jet tube 226 is used to eject the high-speed compressed air introduced by the air guide 224 from its air outlet. A dust suction port 2261 is arranged on the side of the jet tube 226. The dust suction port 2261 is sealed and connected to the dust guide 225. ;

[0027] 1. The steps of using the above-mentioned smoke direct-reading measuring instrument calibration system to calibrate the concentration indication error of the smoke direct-reading measuring instrument 40 to be calibrated are as follows: The first step is to open the second test port 161, and place the smoke direct reading measuring instrument 40 to be calibrated and the smoke direct reading measuring instrument 40 with effective traceability (hereinafter referred to as the standard instrument) or the filter membrane sampler at the same cross section in the second test section through the second test port 161; The second step is to start the first fan 18 to generate an air flow field in the wind tunnel 10. The air flow enters from the entrance of the air inlet section 11, is compressed by the first contraction section 12, and then accelerates to pass through the first test chamber 13, so that the wind speed in the first test chamber 13 can reach the maximum value. At the same time, the air compressor 23 is turned on to allow the air guide pipe 224 to pass the high-speed gas into the jet pipe 226 and spray it out from the outlet end of the jet pipe 226. A negative pressure area is generated at the dust suction port 2261 in the jet pipe 226, so that the dust in the dust feeder 21 is quantitatively discharged through the dust guide pipe 225. The dust is sucked into the jet tube 226, and then ejected out of the jet tube 226 and diffused rapidly under the action of the high-speed airflow, and continued to move backward and diffuse under the action of the airflow in the contraction section 12 with an accelerating trend; the airflow in the wind tunnel 10 is decelerated through the diffusion section 14 and diffused fully with a divergent trend, and then the airflow in the turbulent state gradually forms a uniform and stable flow field through the straight pipe section 15 and flows through the second test chamber 16, so that the dust carried in the airflow can form a gas-solid two-phase flow with uniform concentration, sufficient dispersion and uniform mixing in the second test chamber 16; The third step is to run the wind tunnel 10 in the above state for a period of time, and then repeatably compare the measurement values ​​of the smoke direct-reading tester to be calibrated with those of the standard instrument (or filter membrane sampler weighing) to complete the calibration of the concentration indication error of the smoke direct-reading measuring instrument 40 to be calibrated in a relatively uniform gas-solid two-phase flow field.

[0028] Step 4: After closing the wind tunnel 10, open the first test port 131, and move the smoke direct reading tester and the standard instrument or filter sampler to be calibrated in the second test chamber 16 to the first test chamber 13 and place them at the same cross section; Step 5: Start the first fan 18 to generate an air flow field in the wind tunnel 10 again. The dust emitted by the dust generator diffuses rapidly under the action of the airflow with an accelerating trend in the contraction section 12 and forms a gas-solid two-phase turbulent flow with a relatively high concentration, a low dispersion range, and an insufficient mixing degree in the first test section. Under the disordered disturbance of the turbulent flow, the dust gradually diffuses in the first test section to simulate a smoke environment with a high concentration. The sixth step is to make the wind tunnel 10 run for a period of time in the above state, and then repeatably compare the measurement values ​​of the smoke direct-reading tester to be calibrated with those of the standard instrument (or filter membrane sampler weighing) to complete the calibration of the concentration indication error of the smoke direct-reading measuring instrument 40 to be calibrated in a relatively uniform gas-solid two-phase flow field.

[0029] 2. The steps of calibrating the wind speed indication of the smoke direct-reading measuring instrument 40 to be calibrated using the above-mentioned smoke direct-reading measuring instrument calibration system are roughly the same as the steps of calibrating the above-mentioned concentration indication. The present application does not elaborate on the repetitive steps. The biggest difference from the concentration indication calibration is: replacing the standard instrument (or filter membrane sampler weighing) with a standard anemometer that has been traced and calibrated; in the first test chamber 13, under the conditions of the highest wind speed and the largest wind speed variation range and the most unstable air flow field in the wind tunnel 10, the wind speed indication of the standard anemometer is compared with the wind speed indication of the calibrated instrument to complete the calibration of the wind speed indication error of the smoke direct-reading meter; in the second test chamber 16, by adjusting the wind speed of the first fan 18, a stable flow field with increasing or decreasing speed is generated in the second test chamber 16, so as to measure the isokinetic tracking response time (i.e., the reaction time of the reading) of the wind speed indication of the smoke direct-reading measuring instrument 40.

[0030] The smoke direct reading measuring instrument calibration system of the present application has the following beneficial effects: First, the system can be used to simulate smoke environments of different states between relatively high concentration and low concentration in the first test chamber 13 and the second test chamber 16, and to test and calibrate the smoke direct-reading measuring instrument 40 to be calibrated, so that the smoke direct-reading measuring instrument 40 can perform smoke concentration indication error tests in an environment with a large smoke concentration variation range and an environment with a stable concentration, respectively, so as to improve the authenticity and integrity of the smoke environment simulation; the system can also enable the smoke direct-reading measuring instrument 40 to perform wind speed indication error tests and reading response speed tests in an environment with a large wind speed variation range and a high complexity of the airflow flow field and an environment with controllable wind speed changes and a stable airflow flow field, respectively. Compared with the prior art, a more comprehensive and complete test environment can be provided in the calibration operation of the smoke direct-reading tester, thereby avoiding the problem of large test errors caused by insufficient environmental simulation range; 2. The dust generating device 20 in the present system not only has the function of increasing the ejection velocity and kinetic energy of the dust by cooperating with the diffusion structure through the jet tube 226 that ejects high-speed and high-pressure airflow, but also has the function of pre-diffusion of the dust. After the dust is initially diffused in the diffusion component, it is diffused for the second time through the convergence-diffusion structure of the wind tunnel 10, which further improves the diffusion efficiency and diffusion range of the dust, making the discharge of the dust more uniform and smooth. Compared with the prior art, it can simulate a smoke environment with more stable concentration, more complete diffusion and more uniform mixing in the second test chamber 16, which helps to improve the accuracy of the indication of the smoke direct-reading measuring instrument 40 and make the calibration work meet higher verification standards.

[0031] In addition, the present application also provides some more specific implementation methods to improve the calibration system of the above-mentioned smoke direct-reading measuring instrument.

[0032] Furthermore, the air inlet of the air inlet section 11 is in the form of an arc-shaped air inlet 111, that is, the front lip of the air inlet is in the form of an arc surface, which can reduce the airflow resistance at the air inlet of the wind tunnel 10 and increase the smoothness of air intake; between the arc-shaped air inlet 111 and the contraction section 12, a honeycomb rectifying plate 112, three rectifying nets 113 and a static pressure box 114 are sequentially arranged along the wind direction in the air inlet section 11, the honeycomb rectifying plate 112 and the rectifying net 113 can make the airflow entering the wind tunnel 10 more uniform and stable, the static pressure box 114 can achieve the effect of uniform air supply, reduce the noise of the wind tunnel 10, make the system more environmentally friendly, and at the same time help to improve the concentration and diffusion effect of dust in the contraction section 12.

[0033] Furthermore, in order to facilitate the control of the dust concentration in the wind tunnel 10, the system further includes a wind speed controller 30, which is actually a PLC controller. The air duct 224 is provided with a pressure regulating valve 2241, and the purpose of adjusting the air supply pressure of the air duct 224 is achieved by controlling the opening of the pressure regulating valve 2241, so that the flow rate of compressed air passing through the jet pipe 226 is different, thereby adjusting the dust injection amount; the pressure regulating valve 2241 is preferably an electric valve, and is electrically connected to the first fan 18 and the wind speed controller 30, so that the dust injection amount can be adjusted. The direct-reading dust measuring instrument 40 detects different smoke dust concentrations. When the dust injection amount is adjusted by adjusting the opening of the pressure regulating valve 2241, the wind speed controller 30 can control the power of the first fan 18 based on the opening signal of the pressure regulating valve 2241 to achieve the purpose of controlling the wind speed in the wind tunnel 10. As the opening of the pressure regulating valve 2241 is opened to the target opening corresponding to the dust environment concentration, the power of the first fan 18 is gradually increased. After the wind speed in the wind tunnel 10 is increased to the wind speed to be tested, the dust in the wind tunnel 10 is fully diffused, so that the dust concentration meets the test requirements.

[0034] Furthermore, in order to fix the dust diffusion assembly 22 at the axis of the contraction section 12 so as to reduce the influence on the airflow field in the wind tunnel 10 and improve the uniformity of dust diffusion, a first fixed rib 121 is provided between the first rectifier tube 221 and the contraction section 12. The first rectifier tube 221 is fixed at the axis of the contraction section 12 through the first fixed rib 121, and the windward surface of the first fixed rib 121 is wedge-shaped or arc-shaped, so as to reduce the resistance to the diffused airflow, and the airflow in the contraction section 12 is relatively smooth, avoiding To avoid generating too much turbulence to affect the wind speed test and dust diffusion; and the first fixed rib 121 is penetrated by a through hole 1211, and the through hole 1211 extends from the surface of the first rectifier tube 221 to the outside of the contraction section 12, and the above-mentioned air duct 224 and the dust duct 225 are both arranged in the through hole 1211. Under the protection of the first fixed rib 121, the airflow is prevented from blowing off the air duct 224 and the dust duct 225, and the disturbance effect of the air duct 224 and the dust duct 225 on the airflow in the contraction section 12 is avoided.

[0035] Furthermore, in order to improve the dust generation efficiency of the above-mentioned dust generating device 20, the internal space of the above-mentioned jet tube 226 is adjacent to one end of the air duct 224 and extends backward in a convergent manner in a direction away from the air duct 224, and the other end (i.e., the end of the jet tube 226 that ejects dust) extends backward in a divergent manner in a direction away from the air duct 224.

[0036] Specifically, the above structure makes the jet tube 226 a convergent-straight-divergent tube similar to a Venturi tube or a Laval nozzle, and its dust suction port is arranged before the range of the diffusion tube section. When the high-speed and high-pressure airflow enters the jet tube 226 from the front end, based on the Venturi effect, the airflow is first accelerated through the convergent tube section, and then ejected through the diffusion tube section with relative deceleration, so that the pressure is reduced between the convergent tube section and the straight tube section. Since the airflow velocity outside the jet tube 226 is relatively slow and the pressure is relatively high, a relative negative pressure is formed between the convergent tube section and the straight tube section, which can continuously suck dust out of the dust feeder 21; the diffusion tube section located behind the straight tube section can increase the dust diffusion area, and the dust can be pre-diffused before the second rectifier tube 223 to improve the dispersion of the dust in the flow field.

[0037] Furthermore, in order to improve the pre-diffusion efficiency of dust in the dust diffusion assembly 22, a back-blowing port 2262 is provided on the side of the jet tube 226 along the axial direction of the jet tube 226 between the diffusion-type end of the jet tube 226 and the dust suction port 2261, and the back-blowing port 2262 extends obliquely toward the direction of the dust suction port 2261.

[0038] Specifically, the above-mentioned back-blowing port 2262 arranged in the relative negative pressure zone of the above-mentioned jet tube 226 is also based on the Venturi principle, and can generate a back-blowing airflow in the jet tube 226 in the opposite direction of the dust outflow direction. The back-blowing airflow can blow away the dust at the moment the dust is sucked out of the dust suction port 2261, and the flow rate of the back-blowing airflow is affected by the size of the back-blowing port 2262 and will be much lower than the compressed airflow flowing along the axial direction of the jet tube 226. Without affecting the dust suction out of the above-mentioned negative pressure area, the dust is disturbed and blown away to improve the dust diffusion efficiency.

[0039] Furthermore, in order to enable the dust suction port 2261 to suck out dust with higher efficiency, the dust suction port 2261 should be set at a certain inclination angle to the side of the jet tube 226. Theoretically, the smaller the inclination angle, the closer the angle at which the dust enters the ejector is to 0 degrees, and the smoother the dust is sucked out; similarly, in order to enable the back-blowing airflow at the back-blowing port 2262 to play a role in disturbing the flow and dispersing the dust, when the back-blowing port 2262 and the dust suction port 2261 are in the same straight line, the inclination angle of the above-mentioned back-blowing port 2262 is greater than 0 degrees and less than or equal to 45°, and its inclination angle is opposite to that of the above-mentioned dust suction port 2261, and is within a range of no more than 45°, thereby ensuring good disturbing and dispersing effects on the dust.

[0040] Furthermore, in order to enable the above-mentioned dust generating device 20 to generate dust in the wind tunnel 10, improve the dust generation efficiency and ensure the dust generation concentration, the dust diffusion assembly 22 also includes a second fan 227, and the second fan 227 is preferably an axial flow fan, and the air outlet of the second fan 227 is connected to the air inlet of the first rectifier tube 221 through a flange.

[0041] When using the above system, the first fan 18 and the second fan 227 are started at the same time to blow air into the wind tunnel 10 and the first rectifier tube 221 respectively. The second fan 227 can form a uniform air flow field outside the jet tube 226 to improve the pre-diffusion efficiency of dust in the diffusion space. Compared with other fans such as centrifugal fans, the axial flow fan preferred in this application is used as the second fan 227. Since the axial flow fan is smaller in size, has lower noise and higher air supply efficiency, the axial flow fan can be coaxially connected to the air inlet of the first rectifier tube 221 and arranged in the wind tunnel 10 together with other components of the dust diffusion assembly 22, which not only helps to improve the dust emission efficiency, but also is more in line with the aerodynamic design in the wind tunnel 10, avoiding causing large disturbances to the wind field in the wind tunnel 10, improving the uniformity of the smoke concentration in the smoke simulation environment, and further reducing the calibration error caused to the smoke direct reading measuring instrument 40.

[0042] Furthermore, a conical breaking body 228 is sleeved in the conical tube 222, and the conical breaking body 228 forms a first diffusion space and a second diffusion space respectively along the jet direction away from the jet tube 226 through the conical end surface with the inner wall of the conical tube 222 and the inner wall of the second rectifier tube 223, and the first diffusion space is connected with the second diffusion space.

[0043] When the above system is used, the dust entering the jet tube 226 is ejected from the jet tube 226 under the action of high-speed compressed air and rapidly diffused under the action of the wind field in the first rectifier tube 221, which is the first diffusion stage of the dust; the dust in the first rectifier tube 221 flows through the first diffusion space with the wind field, and under the action of the above-mentioned conical breaking body 228, the air flow flowing through the first rectifier tube 221 has a tendency to rapidly diffuse outward from the axis, so that the dust further diffuses in the first diffusion space, which is the second diffusion stage of the dust; the air flow in the conical tube 222 flows through the conical breaking body 228 and enters the second diffusion space. Since the inner diameter of the second rectifier tube 223 is larger than that of the first rectifier tube 221, the dust further diffuses in the second diffusion space, which is the third diffusion stage of the dust. After the dust has undergone at least three consecutive diffusion actions mentioned above, it can achieve an ideal diffusion effect within a limited distance.

[0044] To further improve the dust diffusion efficiency, the end of the conical breaker body 228 adjacent to the first rectifier tube 221 is conical, and its vertex angle (the vertex angle refers to the vertex angle of the conical end of the conical breaker body 228) is greater than the vertex angle of the conical tube 222.

[0045] Specifically, along the direction opposite to the direction pointed by the tip of the above-mentioned apex angle, the conical surface of the conical breaking fluid 228 and the inner wall of the conical tube 222 form an annular first diffusion space, and the first diffusion space is gradually converged from the tip to the plane where the bottom surface of the cone is located, so that the airflow has an acceleration effect in the first diffusion space. The dust is rapidly diffused in the first diffusion space under the influence of the conical breaking fluid 228 and then gathered to increase the dust concentration, and then further diffused in the second diffusion space. In the flow state of continuous dispersion, convergence and then dispersion of the airflow, the mixing effect of the dust is enhanced and the diffusion efficiency is further improved.

[0046] Furthermore, in order to fix the above-mentioned conical breaking body 228, a plurality of second fixed ribs 2221 are arranged at annular intervals between the above-mentioned conical breaking body 228 and the conical tube 222, and the conical breaking body 228 is connected to the inner wall of the conical tube 222 through the above-mentioned plurality of second fixed ribs 2221, and a channel connecting the above-mentioned first diffusion space and the second diffusion space is formed between the adjacent second fixed ribs 2221; in order to reduce the windward area of ​​the second fixed ribs 2221, enhance the flow breaking effect of the second fixed ribs 2221, and increase the dust concentration between the first diffusion space and the second diffusion space, the windward surface of the above-mentioned second fixed ribs 2221 (i.e., the surface on one side facing the first diffusion space) is chamfered to make it wedge-shaped or arc-shaped, so as to reduce the resistance to the diffused airflow, make the streamlines of the airflow after diffusion through the first diffusion space relatively gathered and stabilized, and make the dust concentration between the first diffusion space and the second diffusion space increased, so as to facilitate the dust to have a better diffusion effect after entering the second diffusion space.

[0047] Furthermore, in order to increase the degree of dispersion of dust when flowing through the second diffusion space, so that it can be further diffused in the wind field after flowing out of the second rectifier tube 223, a spoiler paddle 229 is provided in the second diffusion space, and the axis of the spoiler paddle 229 is rotatably connected to the end of the conical fluid breaking body 228 away from the first rectifier tube 221.

[0048] Specifically, the spoiler paddle 229 includes a hub, a plurality of blades and a rotating shaft, one end of the rotating shaft is fixedly connected to the axis of the hub, and the other end is rotatably connected to the rear end of the conical breaking body 228 through a bearing, and the plurality of blades are arranged in an annular space around the hub. The spoiler paddle 229 rotates under the action of the airflow flowing out of the second rectifier tube 223, so that the airflow produces a rotating effect, so that the dust is distributed more discretely under the rotating airflow and the rotating disturbance of the spoiler paddle 229. After the dust flows out of the second rectifier tube 223 with the airflow, it is further dispersed in the wind field of the wind tunnel 10 under the centrifugal action.

[0049] In combination with the multiple structures and features in the above-mentioned embodiments, the wind tunnel 10 of the above-mentioned smoke direct-reading measuring instrument calibration system can simulate a smoke environment with uniform concentration and high dust diffusion degree, so as to improve the calibration standard of the smoke direct-reading measuring instrument 40 and reduce the calibration error caused by insufficient or distorted environmental simulation conditions.

[0050] Obviously, the above embodiments of the present application are merely examples for clearly illustrating the present application, and are not intended to limit the implementation methods of the present application. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A smoke direct reading measuring instrument calibration system, characterized in that: The invention comprises a dust generating device and a wind tunnel, wherein the wind tunnel comprises an air inlet section, a contraction section, a first test chamber, a diffusion section, a straight pipe section, a second test chamber, a dust removal section and a first fan which are connected in sequence, wherein the surface of the first test chamber can be opened to be provided with a first test port, and the surface of the second test chamber can be opened to be provided with a second test port; the dust generating device comprises a dust feeder and a dust diffusion assembly which is arranged at the junction of the air inlet section and the contraction section, wherein the dust diffusion assembly comprises a first rectifier tube, a conical tube and a second rectifier tube which are connected in sequence along the wind direction of the wind tunnel The small mouth of the conical tube is connected to the first rectifier tube, and the large mouth of the conical tube is connected to the second rectifier tube. An air guide tube and a dust guide tube are arranged on the side of the first rectifier tube. One end of the dust guide tube extends beyond the contraction section and is connected to the dust feeder. A jet tube is axially sleeved in the first rectifier tube. The air inlet of the jet tube is connected to the air guide tube. The air guide tube is used to pass compressed air into the jet tube. A dust suction port is arranged on the side of the jet tube, and the dust suction port is connected to the dust guide tube.

2. The smoke direct reading measuring instrument calibration system according to claim 1 is characterized in that: The front lip of the air inlet of the air inlet section is arc-shaped, and a honeycomb rectifier plate, a plurality of rectifier nets and a static pressure box are sequentially arranged along the wind direction of the wind tunnel between the air inlet of the air inlet section and the contraction section.

3. The smoke direct reading measuring instrument calibration system according to claim 1 is characterized in that: A first fixed rib is provided between the first rectifier tube and the inner wall of the contraction section, the first rectifier tube is fixed to the axis of the contraction section through the first fixed rib, the windward surface of the first fixed rib is wedge-shaped or arc-shaped, and the first fixed rib is provided with a through hole passing through the contraction section, and the air guide tube and the dust guide tube are located in the through hole.

4. The smoke direct reading measuring instrument calibration system according to claim 1 is characterized in that: The inner space of the jet tube is convergent at one end adjacent to the air guide tube in a direction away from the air guide tube, and divergent at the other end in a direction away from the air guide tube.

5. The smoke direct reading measuring instrument calibration system according to claim 4 is characterized in that: Along the axial direction of the jet tube, a back-blowing port is provided on the side surface of the jet tube between the end of the jet tube in a diffused shape and the dust suction port, and the back-blowing port is inclined toward a direction close to the dust suction port.

6. The smoke direct reading measuring instrument calibration system according to claim 5 is characterized in that: The inclination angle of the back-blowing port is greater than 0° and less than or equal to 45°.

7. The smoke direct reading measuring instrument calibration system according to claim 1 is characterized in that: The dust diffusion assembly further includes a second fan, which is an axial flow fan, and an air outlet of the second fan is connected to an air inlet of the first rectifier tube.

8. The smoke direct reading measuring instrument calibration system according to claim 1 is characterized in that: A conical breaker body is sleeved in the conical tube, and the conical breaker body, the conical tube and the second rectifying tube respectively form a first diffusion space and a second diffusion space in a direction away from the jet tube, and the first diffusion space is connected with the second diffusion space.

9. The smoke direct reading measuring instrument calibration system according to claim 8, characterized in that: One end of the conical breaker body adjacent to the first rectifier tube is conical, and its vertex angle is greater than the vertex angle of the conical tube.

10. The smoke direct reading measuring instrument calibration system according to claim 8, characterized in that: A plurality of second fixed ribs are arranged annularly between the conical breaker body and the conical tube, the conical breaker body is connected to the conical tube through the second fixed ribs, and the windward surface of the second fixed ribs is wedge-shaped or arc-shaped.

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