A sheath flow device for a particle size spectrometer

Abstract

The utility model discloses a kind of sheath flow devices of particle size spectrometer, including sample gas inlet pipe, sheath gas inlet pipe, mixed flow cover and sheath flow ring, mixed flow cover has hollow cavity, sample gas inlet pipe is communicated with hollow cavity, sheath flow ring is filled with high-efficiency filter filter core inside, sheath flow ring is detachably installed on mixed flow cover and hollow cavity is communicated with sheath flow ring by multiple through holes, sheath gas inlet pipe is communicated with sheath flow ring by multiport valve, electromagnetic valve and monitoring instrument are equipped on sheath gas inlet pipe, the gas inlet end of sheath gas inlet pipe is connected with air pump, heating element is equipped inside sheath gas inlet pipe;The utility model can increase the uniformity of sheath flow, make sheath gas keep laminar flow state, conveniently and quickly replace filter core, uniformly disperse sheath gas, accurately control sheath gas flow, guarantee the accuracy of test, realize to sheath gas flow dynamic adjustment, realize the temperature control of sheath gas, avoid temperature to cause influence on measurement accuracy.

Description

Technical Field

[0001] This utility model relates to the field of atmospheric particulate matter detection technology, and in particular to a sheath flow device for a particle size spectrometer. Background Technology

[0002] Particle size spectrometers are used for particle size spectrum analysis of atmospheric particulate matter, enabling real-time, online, and high-resolution measurement of the mass concentration and number concentration of atmospheric particulate matter within a certain particle size range. In the sample introduction system of a particle size spectrometer, the design of the sheath gas structure is a crucial optimization for improving measurement accuracy. The core principle is inspired by flow cytometry, using hydrodynamic focusing to confine particles to the central streamline of the detection zone, enveloping the sample gas to prevent diffusion, ensuring that particles pass through the optical detection area one by one at a uniform speed, forming an air curtain to isolate and prevent particulate matter from impacting / depositing on the inner wall of the detection chamber and the optical window, thus protecting the instrument from contamination.

[0003] Chinese patent application number 202120444031.1 discloses a sample gas / sheath gas mixing device for an aerodynamic particle size spectrometer, comprising: a sample gas inlet pipe, a sheath gas inlet pipe, a mixing jacket, and a mixing jacket compression cap assembly; the mixing jacket is a hollow structure and is sealed to the mixing jacket compression cap assembly, forming a closed space with the aerosol inlet pipe of the aerodynamic particle size spectrometer; the sample gas inlet pipe passes through the mixing jacket compression cap assembly and the hollow structure, and is used to connect to the air inlet of the aerodynamic particle size spectrometer; the sheath gas inlet pipe passes through the mixing jacket, and is used to input indoor air into the hollow structure of the mixing jacket.

[0004] Chinese patent application number 202020360339.3 discloses an optical equivalent particle size spectrometer with an internal circulation sheath flow structure, including a gas path module, an optical path module, and an analog-to-digital conversion module. The gas path module includes an inlet gas pipe, an outlet gas pipe, and a sheath flow pipe. The sheath flow pipe is sleeved on the outer circumference of the inlet gas pipe and is coaxially arranged with the inlet gas pipe. An annular hole for sheath gas to pass through is formed between the sheath flow pipe and the inlet gas pipe. The optical path module includes a light source, an ellipsoidal reflector and a lens group, and a photoelectric converter. The light path emitted by the light source is located on a plane perpendicular to the axis of the inlet gas pipe. The major axis of the ellipsoidal reflector is perpendicular to the light path emitted by the light source, and the front focal point of the ellipsoidal reflector is located at the intersection of the light path emitted by the light source and the axis of the inlet gas pipe. The front focal point of the lens group coincides with the rear focal point of the ellipsoidal reflector. The photosensitive area of ​​the photoelectric converter is located at the rear focal point of the lens group.

[0005] The existing sheath flow structure has the following problems: 1. The sheath flow enters the sheath flow tube from a single sheath gas inlet, which easily leads to turbulence; 2. The sheath flow is recycled, which may accumulate contaminants and makes it impossible to quickly replace the sheath gas filter; 3. It is impossible to accurately control the sheath flow rate and dynamically adjust the sheath flow rate; 4. The temperature of the sheath flow is not controlled to eliminate the impact of thermal effects on detection accuracy.

[0006] To address these issues, this application proposes a sheath flow device for a particle size spectrometer. Utility Model Content

[0007] The technical problem to be solved by this utility model is to provide a sheath flow device for a particle size spectrometer that allows for precise control and dynamic adjustment of sheath gas flow rate and temperature, and ensures uniform sheath flow.

[0008] To solve the above-mentioned technical problems, this utility model includes a sample gas inlet pipe, a sheath gas inlet pipe, a mixing jacket, and a sheath flow ring. The mixing jacket has a hollow cavity, and the sample gas inlet pipe is connected to the hollow cavity. The sheath flow ring is filled with a high-efficiency filter element. The sheath flow ring is detachably installed on the mixing jacket, and the hollow cavity is connected to the sheath flow ring through multiple through holes. The sheath gas inlet pipe is connected to the sheath flow ring through a multi-port valve. The sheath gas inlet pipe is equipped with a solenoid valve and a monitoring instrument. The inlet end of the sheath gas inlet pipe is connected to an air pump, and a heating element is provided inside the sheath gas inlet pipe.

[0009] Preferably, the upper part of the mixing jacket is cylindrical and the lower part is tapered, and the lower part of the mixing jacket is open and has a threaded line on the outside, and the through hole is located in the upper part of the mixing jacket.

[0010] Preferably, the through holes are circumferentially distributed and are inclined downward from the outside to the inside of the mixing jacket.

[0011] Preferably, the sample gas inlet pipe is coaxially arranged with the mixing jacket, and the lower end of the sample gas inlet pipe extends to the constriction section of the mixing jacket.

[0012] Preferably, a limiting platform is fixed on the outer side of the mixing jacket, the sheath flow ring is slidably sealed to the outer side of the mixing jacket, and the lower end of the sheath flow ring is in contact with the limiting platform.

[0013] Preferably, the sheath flow ring includes an inner ring and an outer ring arranged coaxially, the inner ring is sleeved on the outside of the mixing jacket, the high-efficiency filter element is disposed between the inner ring and the outer ring, and the inner ring communicates with the through hole on the mixing jacket.

[0014] Preferably, the outer ring is provided with at least two sheath gas inlets, which are distributed circumferentially on the outer ring. The multi-way valve is installed on the sheath gas inlet, and the multi-way valves are connected by hoses, with one of the multi-way valves connected to the sheath gas inlet pipe.

[0015] Preferably, the monitoring instrument includes a temperature sensor and a flow sensor.

[0016] Preferably, the heating element is a spiral heating wire and is disposed on the inner wall of the sheath gas inlet pipe along the axial direction of the sheath gas inlet pipe.

[0017] Preferably, the end of the sheath air inlet pipe near the air pump is filled with an inefficient filter element.

[0018] The beneficial effects of this utility model are as follows: By setting a sheath flow ring, this utility model can increase the uniformity of the sheath flow, keeping the sheath gas in a laminar flow state. The sheath flow ring is detachable, making it convenient and quick to replace the filter element. The multi-way valve can evenly disperse the sheath gas, preventing the sheath gas from entering the mixing jacket through a certain through hole of the sheath flow ring and causing turbulence. The air pump, together with the solenoid valve and monitoring instrument, can accurately control the sheath gas flow rate, ensuring the accuracy of the test and realizing dynamic adjustment of the sheath gas flow rate. The heating element can heat the sheath gas, and together with the monitoring instrument, it can realize the temperature control of the sheath gas, avoiding the influence of temperature on the measurement accuracy. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the sheath flow ring structure in this utility model.

[0020] In the diagram: 1. Sample gas inlet pipe; 2. Sheath gas inlet pipe; 3. Mixing jacket; 301. Hollow cavity; 302. Through hole; 303. Limiting platform; 4. Sheath flow ring; 401. Outer ring; 402. Inner ring; 403. High-efficiency filter element; 404. Sheath gas inlet; 405. Flexible hose; 5. Air pump; 6. Low-efficiency filter element; 7. Solenoid valve; 8. Monitoring instrument; 9. Heating element; 10. Multi-port valve. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. All directional indicators (such as up, down, left, right, front, back, etc.) in the present utility model are only used to explain the relative positional relationship and movement of each component in a certain posture (as shown in the accompanying drawings). If the specific posture changes, the directional indicator will also change accordingly.

[0022] like Figure 1 , Figure 2As shown, this embodiment provides a sheath flow device for a particle size spectrometer, including a sample gas inlet pipe 1, a sheath gas inlet pipe 2, a mixing jacket 3, and a sheath flow ring 4. The mixing jacket 3 has a hollow cavity 301 inside. The upper part of the mixing jacket 3 is cylindrical, and the lower part is a constricted cone. The lower part of the mixing jacket 3 is open and has a threaded outer side. The shape of the hollow cavity 301 matches the outer dimensions of the mixing jacket 3, that is, the upper part of the hollow cavity 301 is cylindrical and the lower part is conical. The sample gas inlet pipe 1 is coaxially arranged with the mixing jacket 3 and communicates with the hollow cavity 301. The lower part of the sample gas inlet pipe 1... The sheath ring 4 extends to the constricted section of the mixing jacket 3. The sheath ring 4 is filled with a high-efficiency filter element 403. The sheath ring 4 is detachably mounted on the mixing jacket 3, and the hollow cavity 301 communicates with the sheath ring 4 through multiple through holes 302. Specifically, a limiting platform 303 is fixed to the outer side of the mixing jacket 3, and the sheath ring 4 is slidably sealed to the outer side of the mixing jacket 3. Specifically, sealing rings are embedded at the upper and lower ports of the sheath ring 4 on the outer side of the mixing jacket 3, facilitating the disassembly of the sheath ring 4. Furthermore, to facilitate the alignment of the through holes 302, the contact surface between the sheath ring 4 and the mixing jacket 3 is... The axially designed limiting structure, consisting of protrusions and grooves, achieves circumferential limiting of the sheath flow ring 4. The lower end of the sheath flow ring 4 fits against the limiting platform 303, enabling rapid replacement of the internal high-efficiency filter element 403. Four orifices 302 are located on the upper part of the mixing jacket 3, arranged circumferentially. These orifices guide the sheath flow into the hollow cavity 301 of the mixing jacket 3. The orifices 302 are angled downwards from the outside to the inside of the mixing jacket 3, allowing the sheath gas to converge towards the center of the mixing jacket 3, thus better encapsulating the sample gas. The sheath gas inlet pipe 2, through multiple... Valve 10 is connected to sheath flow ring 4. Sheath gas inlet pipe 2 is equipped with solenoid valve 7 and monitoring instrument 8. Solenoid valve 7 is a miniature structure. Monitoring instrument 8 includes temperature sensor and flow sensor. The inlet end of sheath gas inlet pipe 2 is connected to air pump 5. Sheath gas inlet pipe 2 is equipped with heating element 9. The setting of air pump 5 and monitoring instrument 8 can accurately control sheath gas flow and ensure the accuracy of the test. The setting of solenoid valve 7, together with flow sensor, can realize dynamic adjustment of sheath gas flow. The end of sheath gas inlet pipe 2 near air pump 5 is filled with low-efficiency filter element 6 for initial filtration of sheath gas.

[0023] like Figure 2 As shown, the sheath flow ring 4 further includes an inner ring 402 and an outer ring 401 coaxially arranged. The inner ring 402 is sleeved on the outside of the mixing jacket 3. The high-efficiency filter element 403 is disposed between the inner ring 402 and the outer ring 401. The inner ring 402 is connected to the through hole 302 on the mixing jacket 3. That is, the inner ring 402 is provided with an inlet that corresponds one-to-one with the through hole 302 on the mixing jacket 3. In use, the sheath gas in the sheath gas inlet pipe 2 enters the sheath flow ring 4 and enters the hollow cavity 301 evenly through the through hole 302 on the mixing jacket 3 to form a sheath flow laminar flow.

[0024] At least two sheath gas inlets 404 are provided on the outer ring 401, and the sheath gas inlets 404 are distributed circumferentially on the outer ring 401. A multi-way valve 10 is installed on the sheath gas inlet 404, and the multi-way valves 10 are connected to each other by a hose 405. One of the multi-way valves 10 is connected to the sheath gas inlet pipe 2. The arrangement of multiple sheath gas inlets 404 can make the sheath gas enter the interior of the sheath flow ring 4 evenly, and can evenly disperse the sheath gas, preventing the sheath gas from entering the mixing jacket 3 through a certain inlet of the sheath flow ring 4 and causing turbulence.

[0025] The heating element 9 is a spiral heating wire and is arranged along the axial direction of the sheath gas inlet pipe 2 on the inner wall of the sheath gas inlet pipe 2. The heating element 9 can also be replaced by a heating strip or heating ring, which is embedded in the inner wall of the sheath gas inlet pipe 2. The heating element 9, together with the temperature sensor, can realize the temperature control of the sheath gas and avoid the temperature from affecting the measurement accuracy.

[0026] Its working principle is as follows: the sheath flow ring 4 is detachably connected to the mixing jacket 3, allowing the sheath flow ring 4 to be quickly removed from the top of the mixing jacket 3, enabling timely replacement of the high-efficiency filter element 403 inside the sheath flow ring 4. The multiple sheath gas inlets 404 and multiple through holes 302 on the sheath flow ring 4 allow the sheath gas to enter the mixing jacket 3 evenly, maintaining a laminar flow state and playing a better role in encapsulating the sample flow. Furthermore, the electromagnetic pump, monitoring instrument 8, and solenoid valve 7 can accurately control the sheath gas flow rate and maintain a constant sheath flow ratio. In addition, by adjusting the solenoid valve 7, the sheath gas flow rate can be dynamically adjusted according to the sample gas concentration. The heating element 9 and monitoring instrument 8 in the sheath gas inlet pipe 2 can maintain a constant temperature for the sheath gas, eliminating the influence of thermal effects on the test.

[0027] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sheath flow device for a particle size spectrometer, characterized in that, It includes a sample gas inlet pipe, a sheath gas inlet pipe, a mixing jacket, and a sheath flow ring. The mixing jacket has a hollow cavity, and the sample gas inlet pipe is connected to the hollow cavity. The sheath flow ring is filled with a high-efficiency filter element. The sheath flow ring is detachably installed on the mixing jacket, and the hollow cavity is connected to the sheath flow ring through multiple through holes. The sheath gas inlet pipe is connected to the sheath flow ring through a multi-port valve. The sheath gas inlet pipe is equipped with a solenoid valve and a monitoring instrument. The inlet end of the sheath gas inlet pipe is connected to an air pump, and a heating element is installed inside the sheath gas inlet pipe.

2. The sheath flow device for a particle size spectrometer according to claim 1, characterized in that, The upper part of the mixing jacket is cylindrical and the lower part is tapered. The lower part of the mixing jacket is open and has a threaded line on the outside. The through hole is located in the upper part of the mixing jacket.

3. The sheath flow device for a particle size spectrometer according to claim 2, characterized in that, The through holes are distributed circumferentially, and the through holes are inclined downward from the outside to the inside of the mixing jacket.

4. The sheath flow device for a particle size spectrometer according to claim 2, characterized in that, The sample gas inlet pipe is coaxially arranged with the mixing jacket, and the lower end of the sample gas inlet pipe extends to the constriction section of the mixing jacket.

5. The sheath flow device for a particle size spectrometer according to claim 1, characterized in that, A limiting platform is fixed to the outer side of the mixing jacket, and the sheath flow ring is slidably sealed to the outer side of the mixing jacket, with the lower end of the sheath flow ring fitting against the limiting platform.

6. The sheath flow device for a particle size spectrometer according to claim 1, characterized in that, The sheath flow ring includes an inner ring and an outer ring arranged coaxially. The inner ring is sleeved on the outside of the mixing jacket. The high-efficiency filter element is disposed between the inner ring and the outer ring. The inner ring communicates with the through holes on the mixing jacket.

7. The sheath flow device for a particle size spectrometer according to claim 6, characterized in that, The outer ring is provided with at least two sheath gas inlets, which are distributed circumferentially on the outer ring. The multi-way valve is installed on the sheath gas inlet and the multi-way valves are connected by hoses. One of the multi-way valves is connected to the sheath gas inlet pipe.

8. The sheath flow device for a particle size spectrometer according to claim 1, characterized in that, The monitoring instruments include temperature sensors and flow sensors.

9. The sheath flow device for a particle size spectrometer according to claim 1, characterized in that, The heating element is a spiral heating wire and is arranged along the axial direction of the sheath gas inlet pipe on the inner wall of the sheath gas inlet pipe.

10. The sheath flow device for a particle size spectrometer according to claim 1, characterized in that, The end of the sheath air inlet pipe near the air pump is filled with an inefficient filter element.

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