A short-circuit flow controlled negative pressure cyclone aerosol concentration device and method

Abstract

This invention relates to the field of aerosol separation and enrichment equipment, specifically to a short-circuit flow controlled negative pressure cyclone aerosol concentration device and method. The device includes a hydrocyclone with an upwardly extending overflow pipe coaxially arranged inside, communicating with the hydrocyclone to form a channel for discharging purified gas and providing a negative pressure suction interface. The hydrocyclone has a straight cylindrical section, within which an annular microchannel is coaxially sleeved outside the overflow pipe. The inner wall of the annular microchannel and the outer wall of the overflow pipe form a downwardly discharging short-circuit flow suppression cavity. By setting a coaxial annular microchannel within the straight cylindrical section of the hydrocyclone, the internal flow field is divided into an outer cyclone cavity and a central short-circuit flow suppression cavity. Vertical direct exhaust flow disrupts the short-circuit flow loop region of a traditional hydrocyclone, blocking the path of fine particles escaping directly along the overflow pipe, forcing the escaping particles to return to the cyclone cavity to re-participate in centrifugal separation, thus solving the short-circuit escape problem.

Description

Technical Field

[0001] This invention relates to the field of aerosol separation and enrichment equipment, specifically to a short-circuit flow controlled negative pressure cyclone aerosol concentration device and method. Background Technology

[0002] Sodium-cooled fast reactors, a key development type in fourth-generation nuclear energy systems, use liquid metallic sodium as a coolant. During long-term reactor operation, minor leaks may occur in pipes, valves, steam generators, and other equipment due to thermal fatigue, corrosion, and radiation embrittlement. The leaked liquid sodium rapidly atomizes, generating micro- and nano-sized sodium aerosols, which are quickly diluted by the high-volume ventilation system in the process area, resulting in extremely low concentrations and a wide diffusion range. Therefore, achieving efficient capture and high-concentration of trace sodium aerosols is a prerequisite for achieving ultra-early warning systems, and cyclone enrichment devices are the core components for achieving this goal.

[0003] Currently, aerosol separation and enrichment commonly employs traditional cyclone separators, whose structure mainly consists of a straight section, a conical section, a tangential inlet, an overflow pipe, and a dust collection hopper. During operation, dust-laden gas enters the cylinder through the tangential inlet, forming an outer vortex flowing downwards. Particles are thrown against the wall under centrifugal force and move downwards with the airflow, eventually falling into the lower collection device. The purified gas forms an inner vortex located in the center and flowing upwards, exiting upwards through the central overflow pipe.

[0004] Although traditional hydrocyclones are simple in structure, have no moving parts, are resistant to high temperatures, and are highly reliable, their inherent defects are quite prominent, especially in the field of micro- and nano-particle separation, where they fail to meet the requirements. Specifically: First, during operation, a large short-circuit flow loop with radial centripetal velocity exists at the lower end of the overflow pipe in traditional hydrocyclones. This causes the airflow to carry a large number of insufficiently separated fine particles into the overflow pipe, forming a short-circuit flow escape. For micro- and nano-particles of 0.1–1 μm, their centrifugal force is small, their following tendency is strong, and their escape rate is high, directly leading to a significant decrease in collection efficiency.

[0005] Second, traditional hydrocyclones rely on centrifugal force to separate particles. The smaller the particle diameter, the worse the centrifugal sedimentation effect. Taking submicron-sized sodium aerosol particles generated by sodium leakage in a sodium-cooled fast reactor as an example, the separation efficiency of conventional hydrocyclones is usually less than 70%. A large number of target particles are directly lost with the exhaust gas, and effective enrichment cannot be achieved, resulting in the inability of downstream detection equipment to capture effective signals.

[0006] Third, due to severe short-circuit escape and insufficient effective collection, the concentration ratio of traditional hydrocyclones can usually only reach 10-50, which is far from meeting the high concentration requirements of more than 1000 times in the scenario of large air volume and low concentration leakage of sodium-cooled fast reactors. The detection sensitivity and response speed cannot meet the early warning indicators. Summary of the Invention

[0007] The purpose of this invention is to provide a short-circuit flow controlled negative pressure cyclone aerosol concentration device and method to solve the above-mentioned problems. By setting a coaxial annular microchannel in the straight section of the cyclone separator, the internal flow field is divided into an outer cyclone cavity and a central short-circuit flow suppression cavity. The vertical direct exhaust flow disrupts the short-circuit flow ring region of the traditional cyclone separator, blocking the path of fine particles to escape directly along the overflow pipe, forcing the escaped particles to return to the cyclone cavity to re-participate in centrifugal separation, thus solving the short-circuit escape problem, as detailed below.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a short-circuit flow-controlled negative pressure cyclone aerosol concentrator, comprising: The hydrocyclone has an internally coaxially arranged upward-extending overflow pipe that connects to the hydrocyclone to form a channel for discharging purified gas and provides a negative pressure suction interface. The hydrocyclone has a straight cylindrical section, within which an annular microchannel is coaxially sleeved outside the overflow pipe. The inner wall of the annular microchannel and the outer wall of the overflow pipe form a downward-directed short-circuit flow suppression cavity, used to form a central direct exhaust flow to disrupt the short-circuit flow ring region at the lower end of the overflow pipe. The depth ratio of the microchannel and the overflow pipe inserted into the straight cylindrical section is 0.3-0.8. The outer wall of the annular microchannel and the inner wall of the straight cylindrical section form a swirling cavity, used to generate a three-dimensional rotating turbulent flow field to achieve centrifugal separation of aerosols. The sample inlet tube is connected to both the short-circuit flow suppression chamber and the swirling chamber. It is used to tangentially feed aerosol-containing samples into the swirling chamber and radially feed aerosol-containing samples into the short-circuit flow suppression chamber. The dust collection hopper, located at the bottom of the hydrocyclone, is used to collect the enriched aerosol particles and output the sample; During operation, the aerosol-containing gas flow enters the swirling chamber and the short-circuit flow suppression chamber through the sample inlet tube. The swirling chamber forms a high-speed three-dimensional rotating turbulent flow field on the outer circumference and exhausts gas spirally downward along the wall, causing aerosol particles to migrate and separate towards the wall under the action of centrifugal force and converge towards the dust collection hopper. The short-circuit flow suppression chamber forms a vertical downward exhaust flow in the center, which constrains the flow field and destroys the short-circuit flow ring region through the annular microchannel, preventing unseparated fine particles in the swirling chamber from escaping directly along the overflow pipe, thereby improving the capture efficiency and concentration factor of micro and nano particles.

[0009] Preferably, the straight section is provided with a short-circuit flow inlet that radially penetrates the short-circuit flow suppression cavity, and the outer wall of the straight section is provided with a tangential inlet that connects to the vortex cavity. The sample inlet tube includes a square tube portion fixed to the outer wall of the straight section. The square tube portion is provided with a sample inlet and a short-circuit flow control port. The tangential inlet is connected to the sample inlet, and the short-circuit flow inlet is connected to the short-circuit flow control port, so as to maintain the independent distribution of the two airflows.

[0010] Preferably, the outer port of the square tube is provided with a variable diameter section and a sample inlet connector in sequence, and the sample inlet connector is connected to the square tube through the variable diameter section.

[0011] Preferably, the hydrocyclone further includes a conical section, which is a cylindrical structure with a gradually decreasing diameter. The conical section is used to enhance the swirling intensity and guide the separated particles to converge downwards. The bottom end of the conical section is connected to a fixed flange for sealing and mounting the dust collection hopper.

[0012] Preferably, the dust collection hopper includes a hollow conical shell with a movable flange that is adapted to the fixed flange fixed at the top of the conical shell, and a connecting bolt passing through the movable flange. The outside of the conical shell is connected to an outwardly extending detection return tube and a detection exit tube, and the detection return tube is located above the detection exit tube.

[0013] Preferably, both the return sample tube and the output sample tube are connected to external detection equipment to form a closed sampling and return gas circuit.

[0014] Preferably, the negative pressure suction port at the top of the overflow pipe is a negative pressure fan connector, used to connect an external negative pressure source to form a stable negative pressure driving airflow inside the device.

[0015] Preferably, the annular microchannel is a coaxial annular gap structure, which is used to forcibly separate the outer swirling flow field and the central straight flow field, avoid mutual interference between the two airflows in the straight section, and improve separation stability.

[0016] A short-circuit flow-controlled negative pressure cyclone aerosol concentration method is disclosed. Using the aforementioned short-circuit flow-controlled negative pressure cyclone aerosol concentration device, the aerosol-containing gas is distributed through the inlet tube. A portion enters the cyclone cavity through the tangential inlet to form a three-dimensional cyclone field, causing particle separation and enrichment under centrifugal force. The other portion enters the short-circuit flow suppression cavity through the short-circuit flow inlet to form a central direct discharge flow, disrupting the short-circuit flow loop and preventing direct particle escape, thus achieving aerosol separation and concentration.

[0017] Preferably, the separated and enriched micro- and nano-sized sodium aerosol particles are output from the dust collection hopper to the detection unit for early warning of trace sodium leakage in the sodium-cooled fast reactor process.

[0018] The beneficial effects are as follows: 1. By setting a coaxial annular microchannel in the straight section of the hydrocyclone, the internal flow field is divided into an external swirling cavity and a central short-circuit flow suppression cavity. The vertical direct exhaust flow destroys the short-circuit flow ring area of ​​the traditional hydrocyclone, blocking the path of fine particles to escape directly along the overflow pipe. This forces the escaped particles to return to the swirling cavity to participate in centrifugal separation again, which can reduce the escape rate of micro and nano particles from more than 10% to less than 2% in the traditional way, thus solving the short-circuit escape problem.

[0019] 2. The annular microchannel, as a physical separation structure, forcibly separates the outer swirling flow field from the central straight discharge flow field, avoiding the mixing and disturbance of the two airflows. This makes the swirling flow field more stable and the pressure fluctuation smaller. It can maintain stable separation efficiency under negative pressure drive, flow fluctuation and long-term continuous operation conditions, without clogging or attenuation, and is suitable for the long-term online monitoring requirements of nuclear industry sites.

[0020] 3. Using negative pressure as the separation power, the blower is placed at the outlet end of the overflow pipe, so that the gas containing aerosols is first separated and concentrated by cyclone separation, and then the clean gas comes into contact with the blower. This changes the hazards of direct contact between the blower and unseparated aerosols in the traditional positive pressure sampling, avoids the wear, corrosion and adhesion of sodium aerosol particles to the blower blades and cavity, eliminates the safety hazards of particle accumulation, blockage, heat generation and even combustion and explosion, and improves the safety of nuclear industry on-site operation. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a front view structural diagram of the present invention; Figure 2 This is a three-dimensional structural schematic diagram of the present invention; Figure 3 This is a three-dimensional structural breakdown diagram of the present invention; Figure 4 This is a front sectional view of the present invention; Figure 5 This is a partial cross-sectional view of the present invention; Figure 6 This is a three-dimensional structural schematic diagram of another aspect of the present invention; Figure 7 This is a three-dimensional structural disassembly diagram of another aspect of the present invention; Figure 8 This is a three-dimensional structural disassembled diagram of the sample inlet tube of the present invention; Figure 9 This is a graph showing the change in sodium aerosol detection concentration over time for Group 1 of this invention; Figure 10 This is a graph showing the change in sodium aerosol detection concentration over time for Group 2 of this invention; Figure 11 This is a graph showing the change in sodium aerosol detection concentration over time for Group 3 of this invention.

[0023] The annotations in the attached figures are explained as follows: 1. Hydrocyclone; 101. Straight section; 102. Conical section; 103. Annular microchannel; 104. Short-circuit flow suppression chamber; 104a. Short-circuit flow inlet; 105. Tangential inlet; 106. Hydrocyclone chamber; 107. Fixed flange; 2. Overflow pipe; 201. Negative pressure fan connector; 3. Sample inlet pipe; 301. Square tube section; 301a. Short-circuit flow control port; 301b. Sample inlet; 302. Variable diameter section; 303. Sample inlet connector; 4. Dust collection hopper; 401. Conical shell; 402. Sample return tube; 403. Sample exit tube; 404. Movable flange; 404a. Connecting bolt. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0025] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0026] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] See Figures 1-11 As shown, the present invention provides a short-circuit flow controlled negative pressure cyclone aerosol concentrator, comprising: The hydrocyclone 1 has an internally coaxially arranged upward-extending overflow pipe 2, which communicates with the hydrocyclone 1 to form a channel for discharging purified gas and provides a negative pressure suction interface. The hydrocyclone 1 has a straight cylindrical section 101, within which a coaxially fitted annular microchannel 103 located outside the overflow pipe 2 is used to divide the internal space of the hydrocyclone 1 into an independent outer swirling flow region and a central control region, structurally avoiding mutual interference of the flow fields. The inner wall of the annular microchannel 103 and the outer wall of the overflow pipe 2 form a downwardly direct short-circuit flow suppression cavity 104, used to form a central direct exhaust flow to disrupt the short-circuit flow ring region at the lower end of the overflow pipe, thereby structurally eliminating the limitations of traditional hydrocyclones. The unsolvable short-circuit flow escape problem forces fine particles to re-enter the separation zone; the depth ratio of the microchannel 103 and the overflow pipe 2 inserted into the straight section 101 is 0.3-0.8, ensuring that the bottom opening of the microchannel 103 is higher than the bottom opening of the overflow pipe 2, ensuring that the short-circuit flow can block the outer swirling flow, preventing unseparated particles from being directly discharged outward along the bottom opening of the overflow pipe 2, thereby forming a swirling cavity 106 on the outer wall of the annular microchannel 103 and the inner wall of the straight section 101, which is used to generate a three-dimensional rotating turbulent flow field to achieve centrifugal separation of aerosols, thereby allowing micro- and nano-sized sodium aerosol particles to migrate rapidly towards the wall under the action of strong centrifugal force, achieving efficient separation; The sample inlet tube 3 is connected to both the short-circuit flow suppression chamber 104 and the swirling chamber 106. It is used to send aerosol-containing samples tangentially into the swirling chamber 106 and aerosol-containing samples radially into the short-circuit flow suppression chamber 104. It can realize independent control and precise distribution of the two gas inlets, ensuring that the swirling flow field and the short-circuit suppression field work stably at the same time without interfering with each other. The dust collection hopper 4 is located at the bottom of the hydrocyclone 1 and is used to collect the enriched aerosol particles and output the sample to provide a high-concentration and high-stability sample for subsequent high-sensitivity detection equipment, so as to meet the requirements of ultra-early warning. During operation, the aerosol-containing gas flow enters the swirling cavity 106 and the short-circuit flow suppression cavity 104 through the sample inlet tube 3. The swirling cavity 106 forms a high-speed three-dimensional rotating turbulent field on its outer circumference and exhausts gas spirally downward along the wall, causing aerosol particles to migrate and separate towards the wall under centrifugal force and converge towards the dust collection hopper 4. Afterward, the particles slide steadily down the wall of the conical section 102, achieving continuous and efficient enrichment and collection. The short-circuit flow suppression cavity 104 forms a vertical downward straight exhaust flow in the center, which constrains the flow field and destroys the short-circuit flow loop region through the annular microchannel 103, blocking the direct escape and discharge of unseparated fine particles in the swirling cavity 106 along the overflow pipe 2, thereby improving the capture efficiency and concentration factor of micro and nano particles. Specifically, it can reduce the particle escape rate of traditional hydrocyclones from more than 110% to less than 2%, achieve a capture efficiency of more than 95% for 0.1-1μm sodium aerosols, and achieve a concentration factor of more than 1000 times.

[0029] As an optional implementation, a short-circuit flow inlet 104a is provided radially through the short-circuit flow suppression cavity 104 inside the straight section 101, and a tangential inlet 105 is provided tangentially through the outer wall of the straight section 101, communicating with the vortex cavity 106. The sample inlet tube 3 includes a square tube portion 301 fixed to the outer wall of the straight section 101. The square tube portion 301 is provided with a sample inlet 301b and a short-circuit flow control port 301a. The tangential inlet 105 is connected to the sample inlet 301b, and the short-circuit flow inlet 104a is connected to the short-circuit flow control port 301a, maintaining independent distribution of the two airflows. This ensures that the vortex cavity 106 and the short-circuit flow suppression cavity 104 each obtain a stable and matched airflow volume, maintaining the dynamic balance of the flow field. With this configuration, the ratio of the two airflows inside and outside can be precisely controlled through the dual independent airflow structure, maximizing the separation and suppression effect. The outer port of the square tube section 301 is provided with a reducing section 302 and a sample inlet connector 303 in sequence. The sample inlet connector 303 is connected to the square tube section 301 through the reducing section 302, thereby achieving smooth connection with the external sampling pipeline, reducing air intake resistance, and avoiding airflow disturbance and eddy current generation. This configuration can ensure uniform and stable air intake, improve the reliability of device operation, and facilitate installation and disassembly, adapting to the rapid maintenance needs of nuclear industry sites. The hydrocyclone 1 also includes a conical section 102, which is a cylindrical structure with a diameter that gradually narrows downwards. The conical section 102 is used to enhance the swirling intensity and guide the separated particles to converge downwards. The bottom end of the conical section 102 is connected to a fixed flange 107 for sealing and mounting the dust collection hopper 4. This configuration can further enhance the centrifugal force field, improve the separation effect of fine particles, and ensure that the particles fall smoothly into the dust collection hopper 4 without rebounding. The dust collection hopper 4 includes a hollow conical shell 401. The top of the conical shell 401 is fixed with a movable flange 404 that is adapted to the fixed flange 107. A connecting bolt 404a passes through the movable flange 404, thereby firmly sealing the hydrocyclone 1 and the dust collection hopper 4 to prevent air leakage and pressure loss that would reduce the separation efficiency. The outside of the conical shell 401 is connected to an outwardly extending sample return tube 402 and a sample output tube 403. The sample return tube 402 is located above the sample output tube 403. This arrangement facilitates the formation of a stable internal flow field and pressure balance, allowing high-concentration samples to be output smoothly and avoiding air blockage or backflow. Both the return sample tube 402 and the output sample tube 403 are connected to external detection equipment, forming a closed sampling and return gas circuit. In this way, the internal pressure of the detection system can be kept stable, the sample delivery is continuous and without pulsation, and the accuracy and repeatability of the detection data can be greatly improved. The negative pressure suction port at the top of the overflow pipe 2 is a negative pressure fan connector 201, which is used to connect an external negative pressure source to form a stable negative pressure driving airflow inside the device. This setting allows the gas containing aerosols to be separated and concentrated first, and then the clean gas enters the fan, completely avoiding the wear, corrosion, adhesion or blockage of the fan by sodium aerosol particles, eliminating safety hazards, and completely changing the harmful mode of the traditional positive pressure fan directly contacting unseparated aerosols. The annular microchannel 103 is a coaxial annular gap structure used to forcibly separate the outer swirling flow field and the central straight flow field, avoiding mutual interference between the two airflows in the straight section 101, improving separation stability, further ensuring that the swirling cavity 106 continuously provides strong centrifugal separation capability, and at the same time allowing the short-circuit flow suppression cavity 104 to stably destroy the vortex core, achieving dual synergy.

[0030] A short-circuit flow-controlled negative pressure cyclone aerosol concentration method is disclosed. Using the aforementioned short-circuit flow-controlled negative pressure cyclone aerosol concentration device, the aerosol-containing gas is distributed through the sample inlet tube 3. A portion enters the cyclone chamber 106 through the tangential inlet 105 to form a three-dimensional cyclone field, causing particle separation and enrichment under centrifugal force. The other portion enters the short-circuit flow suppression chamber 104 through the short-circuit flow inlet 104a to form a central direct discharge flow, disrupting the short-circuit flow loop and preventing direct particle escape, thus achieving aerosol separation and concentration.

[0031] After separation and enrichment, the micro- and nano-sized sodium aerosol particles are output from the dust collection hopper 4 to the detection unit for early warning of trace sodium leakage in the sodium-cooled fast reactor process. Specifically, the device can rapidly enrich the sample under conditions of high-volume dilution and extremely low concentration, significantly shortening the detection response time and achieving ultra-early, highly sensitive, and blind-zone-free online early warning of sodium leakage.

[0032] To verify the technical effectiveness of the short-circuit flow-controlled negative pressure cyclone aerosol concentrator of this invention, four sets of comparative experiments were conducted using the device of this invention and a traditional negative pressure cyclone under the same detection environment, the same gas source concentration, the same sampling flow rate, and the same negative pressure power conditions. The experimental object was micro-nano-scale sodium aerosol generated by a simulated leak in a sodium-cooled fast reactor. The experimental system included an aerosol generating device, a sampling pipeline, the concentrator of this invention, a traditional negative pressure cyclone, a microwave plasma spectroscopy detection unit, and a data acquisition system.

[0033] I. Experimental Conditions Experimental medium: sodium-cooled fast reactor simulating leaked sodium aerosol Sampling flow rate: kept constant throughout. System power: negative pressure drive, fan load is the same. Detection target: 0.1-1μm micro / nano sodium aerosol Environmental conditions: Temperature, humidity, and ventilation conditions should be kept consistent with those of the reactor process. Comparison objects: Experimental group: Short-circuit flow controlled negative pressure cyclone aerosol concentration device of the present invention Control group: Traditional negative pressure cyclones without annular microchannels, short-circuit flow suppression cavities, or short-circuit flow control structures.

[0034] III. Explanation of Experimental Results Group 1 (see Figure 9 Under high-concentration leakage conditions, the device of this invention can quickly trigger an alarm in 220 seconds, with a peak concentration as high as 14389 ppb, and maintain stable detection for 53.2 minutes; traditional negative pressure cyclones respond after 250 seconds, with a peak concentration of 600 ppb, and the signal lasts only 12.4 minutes. Group 2 (see Figure 10 Under medium-concentration leakage conditions, the device of this invention can alarm in 193 seconds, with a peak concentration of 1346 ppb, and can continuously detect for up to 40.3 minutes; traditional negative pressure cyclones have no response.

[0035] Group 3 (see Figure 11 Under low-concentration leakage conditions, the device of this invention will respond with an alarm after 225 seconds, realizing early warning of trace leakage; traditional negative pressure cyclones are completely unable to capture low-concentration aerosols and have no detection data.

[0036] IV. Experimental Conclusions This invention solves the problem of escape of the central vortex core in traditional hydrocyclones by using a short-circuit flow suppression cavity and an annular microchannel structure, achieving a capture efficiency of ≥95% for micro- and nano-sized sodium aerosols and a concentration factor of ≥1000 times.

[0037] Under high, medium, and low concentration leakage simulations, the device of this invention can output detection signals quickly, stably, and accurately. In contrast, traditional negative pressure cyclones have shorter response times, peak concentrations, and detection times under high concentration leakage conditions, and no response, alarm, or detection data under medium and low concentration leakage conditions. Therefore, this invention can achieve ultra-early, highly sensitive, and blind-spot-free online monitoring of trace sodium leakage in sodium-cooled fast reactors, meeting the safety early warning requirements of the nuclear industry.

[0038] This invention solves the short-circuit escape problem by setting a coaxial annular microchannel 103 in the straight section 101 of the hydrocyclone 1, dividing the internal flow field into an outer swirling cavity 106 and a central short-circuit flow suppression cavity 104. The vertical direct exhaust flow disrupts the short-circuit flow ring region of the traditional hydrocyclone 1, blocking the path of fine particles to escape directly along the overflow pipe 2, and forcing the escaped particles to return to the swirling cavity 106 to participate in centrifugal separation again. This can reduce the escape rate of micro and nano particles from more than 10% to less than 2% in the traditional method.

[0039] The annular microchannel 103, as a physical separation structure, forcibly separates the outer swirling flow field from the central straight discharge flow field, avoiding mutual mixing and disturbance between the two airflows. This makes the swirling flow field more stable and the pressure fluctuation smaller. It can maintain stable separation efficiency under negative pressure drive, flow fluctuation and long-term continuous operation conditions, without clogging or attenuation, and is suitable for the long-term online monitoring requirements of nuclear industry sites.

[0040] Using negative pressure as the separation power, the blower is arranged at the outlet end of the overflow pipe 2, so that the gas containing aerosols is first separated and concentrated by cyclone separation, and then the clean gas comes into contact with the blower. This changes the harm of direct contact between the blower and unseparated aerosols in the traditional positive pressure sampling, avoids the wear, corrosion and adhesion of sodium aerosol particles to the blower blades and cavity, eliminates the safety hazards of particle accumulation, blockage, heat generation and even combustion and explosion, and improves the safety of nuclear industry on-site operation.

[0041] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A short-circuit flow control type negative pressure cyclone aerosol concentration device, characterized in that, include: The hydrocyclone (1) has an upward-extending overflow pipe (2) coaxially arranged inside, which is connected to the hydrocyclone (1) to form a channel for discharging purified gas and provide a negative pressure suction interface. The hydrocyclone (1) has a straight section (101). An annular microchannel (103) located outside the overflow pipe (2) is coaxially sleeved inside the straight section (101). The inner wall of the annular microchannel (103) and the outer wall of the overflow pipe (2) form a downward straight-out short-circuit flow suppression cavity (104) to form a central straight exhaust flow to destroy the short-circuit flow ring area at the lower end of the overflow pipe. The depth ratio of the microchannel (103) and the overflow pipe (2) inserted into the straight section (101) is 0.3-0.

8. The outer wall of the annular microchannel (103) and the inner wall of the straight section (101) form a swirling cavity (106) to generate a three-dimensional rotating turbulent field to achieve aerosol centrifugal separation. The sample inlet tube (3) is connected to both the short-circuit flow suppression chamber (104) and the swirling chamber (106), and is used to send the aerosol-containing sample tangentially into the swirling chamber (106) and the aerosol-containing sample radially into the short-circuit flow suppression chamber (104). The dust collection hopper (4) is located at the bottom of the hydrocyclone (1) and is used to collect the enriched aerosol particles and output the sample. During operation, the aerosol-containing gas flow enters the swirling chamber (106) and the short-circuit flow suppression chamber (104) through the sample inlet tube (3). The swirling chamber (106) forms a high-speed three-dimensional rotating turbulent field on the outer circumference and exhausts gas spirally downward along the wall, causing aerosol particles to migrate and separate towards the wall under the action of centrifugal force and converge towards the dust collection hopper (4). The short-circuit flow suppression chamber (104) forms a vertical downward straight exhaust flow in the center, which constrains the flow field and destroys the short-circuit flow ring area through the annular microchannel (103), blocking the unseparated fine particles in the swirling chamber (106) from escaping directly along the overflow pipe (2), thereby improving the capture efficiency and concentration factor of micro and nano particles.

2. The short-circuit flow control type negative pressure cyclone aerosol concentrator according to claim 1, characterized in that, The straight section (101) is provided with a short-circuit flow inlet (104a) that radially penetrates the short-circuit flow suppression cavity (104), and the outer wall of the straight section (101) is provided with a tangential inlet (105) that connects to the vortex cavity (106). The sample inlet tube (3) includes a square tube section (301) fixed to the outer wall of the straight section (101). The square tube section (301) is provided with a sample inlet (301b) and a short-circuit flow control port (301a). The tangential inlet (105) is connected to the sample inlet (301b), and the short-circuit flow inlet (104a) is connected to the short-circuit flow control port (301a), so as to maintain the independent distribution of the two airflows.

3. The short-circuit flow control type negative pressure cyclone aerosol concentrator according to claim 2, characterized in that, The outer port of the square tube section (301) is provided with a variable diameter section (302) and a sample inlet connector (303) in sequence. The sample inlet connector (303) is connected to the square tube section (301) through the variable diameter section (302).

4. The short-circuit flow-regulated negative pressure rotational flow aerosol concentrate device according to claim 1, wherein, The hydrocyclone (1) also includes a conical section (102), which is a cylindrical structure with a diameter that gradually narrows downwards. The conical section (102) is used to enhance the swirling intensity and guide the separated particles to converge downwards. The bottom end of the conical section (102) is connected to a fixed flange (107) for sealing and docking the dust collection hopper (4).

5. The short-circuit flow-regulated negative pressure rotational flow aerosol concentrate device according to claim 4, wherein, The dust collection hopper (4) includes a hollow conical shell (401), the top of which is fixed with a movable flange (404) adapted to a fixed flange (107), and a connecting bolt (404a) is inserted through the movable flange (404). The outside of the conical shell (401) is connected to an outwardly extending detection return tube (402) and a detection exit tube (403), and the detection return tube (402) is located above the detection exit tube (403).

6. The short-circuit flow-regulated negative pressure rotational flow aerosol concentrate device according to claim 5, wherein, The detection return tube (402) and the detection output tube (403) are both connected to external detection equipment, forming a closed sampling and return gas circuit.

7. The short-circuit flow-regulated negative pressure rotational flow aerosol concentrate device according to claim 1, wherein, The negative pressure suction port at the top of the overflow pipe (2) is a negative pressure fan connector (201), which is used to connect an external negative pressure source to form a stable negative pressure driving airflow inside the device.

8. The short-circuit flow-regulated negative pressure rotational flow aerosol concentrate device according to claim 1, wherein, The annular microchannel (103) is a coaxial annular gap structure used to forcibly separate the outer swirling flow field and the central straight flow field, avoiding mutual interference between the two airflows in the straight section (101) and improving separation stability.

9. A short circuit flow regulated negative pressure rotational flow aerosol concentration method, characterized by, Using the short-circuit flow controlled negative pressure cyclone aerosol concentrator as described in any one of claims 1-8, after the aerosol-containing gas is distributed through the sample inlet tube (3), a portion enters the cyclone chamber (106) through the tangential air inlet (105) to form a three-dimensional cyclone field, so that the particles are separated and enriched under centrifugal action; another portion enters the short-circuit flow suppression chamber (104) through the short-circuit flow inlet (104a) to form a central direct discharge flow, which destroys the short-circuit flow loop area and blocks the direct escape of particles, thereby realizing aerosol separation and concentration.

10. The short-circuit flow controlled negative pressure cyclone aerosol concentration method according to claim 9, characterized in that, The separated and enriched micro- and nano-sized sodium aerosol particles are output from the dust collection hopper (4) to the detection unit for early warning of trace sodium leakage between sodium-cooled fast reactor processes.

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