A particle detection sensor and a particle detection method in harsh working conditions

Abstract

The embodiment of the present application discloses a kind of particle detection sensor and particle detection method under harsh working condition, it is related to aerosol detection and monitoring technical field, can improve the detection ability of minimum particle size of micro-nano particle.The present application provides a narrower optical detection area in optical detection system, so that the particles in gas can pass through the detection area as single particle or smaller particle micro-group, can improve the detection accuracy of system;And by light path shaping, the incident light is shot into the detection area in parallel, effectively avoid the influence of refractive index due to high temperature and high pressure;In addition, since adding curved mirror in the detection area to enlarge the receiving angle of scattered light, enhance the received scattered light intensity, improve the accuracy of output signal, so as to improve the detection ability of minimum particle size of micro-nano particle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerosol detection and monitoring, and particularly relates to a particle detection sensor and a particle detection method under harsh working conditions. BACKGROUND

[0002] At present, in some chemical industry production processes taking coal as the main energy, the gas in the process pipeline is often under high temperature and high pressure working conditions, and the temperature and pressure range is 100-1500 DEG C and 1-10 MPa respectively. For example, in the processes of two advanced combustion cycles, coal gasification combined cycle (IGCC) and pressurized fluidized bed combustion combined cycle (PFBC), high temperature and high pressure gas with temperature of 400-950 DEG C and pressure of 2-3 MPa is produced. In these working conditions, a large amount of particulate impurities is contained in the high temperature and high pressure gas due to the existence of high temperature cracking process. On the one hand, they will scour the pipe wall and cause abrasion, reduce the service life of the transportation pipeline, and with the increase of particulate impurities in the process pipeline, the particles will gradually deposit on the inner wall of the pipeline, reduce the cross-sectional area of the pipeline, increase the resistance of the transported gas and reduce the transportation efficiency. On the other hand, the existence of particles will also adhere to the surface of the turbine blade, causing the turbine blade to wear and corrode, and reducing the economic benefit of the power plant.

[0003] In order to control the content of particles in high pressure and high temperature gas, a dust removal and purification system needs to be arranged in the process pipeline. For the purification capacity of these dust removal equipment, particle detection technology is needed to measure the particle size distribution and concentration and other parameters to calculate their separation efficiency and classification efficiency. At present, there are many kinds of particle detection methods, mainly including balance oscillation method, weight method, capacitance and inductance method, image method and light scattering method. Among them, the particle detection scheme based on light scattering method has been widely applied, but there are still some technical defects:

[0004] The optical particle counter in service at present adopts ordinary optical lens group and non-temperature-resistant and pressure-resistant structure design, so its application working conditions and fields are greatly limited, and it is widely applied in powder manufacturing and dust removal equipment design field under normal temperature and pressure. For the particle detection demand under very high temperature and pressure, researchers mainly focus on high temperature and normal pressure and normal temperature and high pressure working conditions. It is necessary to improve the optical sensor to have good temperature-resistant and pressure-resistant performance to adapt to the application working conditions of temperature 100-1500 DEG C and pressure 1-10 MPa; and in addition to breaking through the temperature-resistant and pressure-resistant ability of the detection device, the problem of fluctuation of detection performance of the optical particle counter caused by the change of working condition parameters still needs to be solved.

[0005] The light beam in the optical system of the optical particle counter in service is a Gaussian light beam, which exhibits the characteristic of uneven light energy distribution, which will result in that the voltage signal corresponding to the scattered light signal of the particle cannot meet the standard characteristics of effective information screening, and the measurement error of the particle count and particle size parameters will be generated in the measurement, which directly affects the detection accuracy of the optical sensor. At the same time, it is also difficult for the optical particle counter in service to improve the detection ability of the minimum particle size of micro-nano particles. SUMMARY

[0006] The embodiment of the present application provides a particle detection sensor and a particle detection method in harsh working conditions, which can improve the detection ability of the minimum particle size of micro-nano particles.

[0007] In order to achieve the above purpose, the embodiment of the present application adopts the following technical scheme:

[0008] The particle detection sensor comprises a base, an incident light path system and a scattered light path system.

[0009] The incident light path system is used for receiving the light emitted by the light source (1) and entering the scattered light path system; the light passes through the scattered light path system and finally enters the receiver (13); a light transmission through hole is opened in the base, the light transmission through hole is aligned with the incident light path, and the particle guide pipe (8) is fixed on the base; a signal input port A and a signal output port B are further arranged on the base, the first optical fiber coupler (16) is installed at the signal input port A, the first optical fiber coupler (16) is connected with the light source (1), the second optical fiber coupler (17) is installed at the signal output port B, and the second optical fiber coupler (17) is connected with the receiver (13). The signal input port A and the signal output port B are coupled with the light source (1) and the receiver (13) respectively by the first optical fiber coupler (16) and the second optical fiber coupler (17).

[0010] A particle detection method in harsh working conditions is executed by the particle detection sensor, which comprises:

[0011] The gas containing particles in the gas transmission pipeline is input into the particle guide pipe (8); the light source (1) is started, then the scattered light emitted through the glass window provided on the particle guide pipe (8) is received by the receiver (13), the scattered light signal is obtained, then the scattered light signal is converted into a voltage pulse signal; and the particle size and the particle number are measured according to the amplitude and the count of the voltage pulse signal.

[0012] The particle detection sensor and the particle detection method under harsh working conditions provided by the embodiment of the present application provide a narrow optical detection area in the optical detection system, so that the particles in the gas can pass through the detection area in the form of single particles or small particle clusters, and the detection accuracy of the system can be improved; and the incident light is made to enter the detection area in a parallel manner through light path shaping, so that the influence of the refractive index generated by high temperature and high pressure is effectively avoided; in addition, the receiving angle of the scattered light is enlarged by adding a spherical mirror in the detection area, the received scattered light intensity is enhanced, the accuracy of the output signal is improved, and the detection capability of the minimum particle size of the micro-nano particles is improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0014] Figure 1 The schematic diagram of the design principle provided by the embodiment of the present application;

[0015] Figure 2 The structure diagram of the scattered light path embodied in the optical system provided by the embodiment of the present application

[0016] Figure 3 The transverse sectional view of the particle guide pipe provided by the embodiment of the present application;

[0017] Figure 4 The overall structure diagram of the particle guide pipe provided by the embodiment of the present application, wherein (a) is a bracket fixed type particle guide pipe; (b) is a flange fixed type particle guide pipe;

[0018] Figure 5 The overall structure diagram of the particle optical detection sensor provided by the embodiment of the present application;

[0019] Figure 6 The sensor packaging schematic diagram provided by the embodiment of the present application, wherein (a) is a particle detection packaging schematic diagram, (b) is a bracket fixed type particle guide pipe installation schematic diagram, and (c) is a particle detection packaging schematic diagram;

[0020] Figure 7 The installation detail schematic diagram of the particle guide pipe, wherein a is a flange fixed type particle guide pipe installation schematic diagram, and b is a bracket fixed type particle guide pipe installation schematic diagram;

[0021] Figure 8 The method flow schematic diagram provided by the embodiment of the present application;

[0022] Light source (1), beam shaper (2), first diaphragm (3), converging lens group (4), second diaphragm (5), beam expander lens group (6), multi-reflective optical system (7), plane mirror (7-1), spherical mirror (7-2), off-axis parabolic mirror (7-3), particle guide tube (8), optical trap (9), convex-concave lens group (10), third diaphragm (11), scattered light converging lens group (12), receiver (13), metal tube fixing support (14), welding flange (15), first fiber coupler (16), second fiber coupler (17). DETAILED DESCRIPTION

[0023] For those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments. Hereinafter, the embodiments of the present application will be described in detail, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be explained as a limitation of the present application. Those skilled in the art can understand that, unless specifically stated, the singular form "a", "an" and "the" used herein can also include the plural form. It should be further understood that the phrase "comprising" used in the specification of the present application means that the features, integers, steps, operations, elements and / or components exist, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there can be intermediate elements. In addition, "connected" or "coupled" used herein can include wireless connection or coupling. The phrase "and / or" used herein includes any one of the associated listed items and all combinations of the associated listed items. Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as that of the ordinary skill in the art to which the present application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted with idealized or overly formal meanings unless defined as such.

[0024] The embodiment of the present application provides a kind of particle detection sensor and particle detection method under harsh working conditions, can utilize optical detection particle, mainly through optical system and particle guide pipe two parts.Light is emitted by light source and is parallelly injected into optical measuring body along horizontal direction after shaping.In optical measuring body, the sample to be tested is introduced by particle guide pipe, and interacts with incident light beam, scattering phenomenon occurs, the scattering light of single particle in a certain range is collected, and is used for the measurement of particle size, number and concentration etc.Parameter, as shown in Figure 1 、 5 As shown, comprising:

[0025] Base, incident light path system and scattering light path system;

[0026] The incident light path system is used to receive the light emitted by the light source (1), wherein, in the incident light path system, the light emitted by the light source (1) sequentially passes through the beam shaper (2), the first diaphragm (3), the converging lens group (4), the second diaphragm (5) and the beam expander lens group (6), and is injected into the scattering light path system;The main function of the beam expander lens group (6) is to expand the diameter of the laser and reduce the divergence angle.

[0027] In the scattering light path system, it includes: multi-reflection light path system (7), particle guide pipe (8), convex-concave lens group (10), third diaphragm (11) and scattering light converging lens group (12), light passes through the scattering light path system and finally enters the receiver (13);Wherein, the beam shaper (2), the first diaphragm (3), the second diaphragm (5), the third diaphragm (11), the converging lens group (4), the beam expander lens group (6), the multi-reflection light path system (7), the convex-concave lens group (10) and the scattering light converging lens group (12) constitute an optical system, and the incident light path system and the scattering light path system are coaxially packaged in their respective directions.

[0028] The base is internally provided with a light passing through hole, and the light passing through hole is aligned with the incident light path;For example Figure 6 As shown, the light passing through hole is a hole in the metal base for fixing optical elements and passing light.

[0029] The particle guide pipe (8) is fixed on the base, wherein a through hole C is formed on the base, and the particle guide pipe (8) passes through the through hole C and is fixed;For example Figure 6 As shown in b, the through hole c is a through hole for the particle guide pipe to pass through, and the particle guide pipe can be fixed. Generally speaking, the metal base can adopt a hexahedral metal block (non-metallic materials can also be adopted), and the through hole C is close to a corner of the metal base.

[0030] The light trap (9) is inlaid at the right side D of the particle guide pipe (8); wherein, the light trap is inlaid at the right side of the particle guide pipe, and the light beam which is not scattered and is emitted from the right side window of the particle guide pipe is reflected to the outside of the optical system. In this way, the interference of the excess light beam on the light pulse is avoided. For example Figure 6 c, at the right side D.

[0031] The signal input port A and the signal output port B are further arranged on the base, the first fiber coupler (16) is arranged at the signal input port A and connected with the light source (1), and the second fiber coupler (17) is arranged at the signal output port B and connected with the receiver (13). Figure 6 a, the signal input port A and the signal output port B are coupled with the light source (1) and the receiver (13) respectively by the first fiber coupler (16) and the second fiber coupler (17).

[0032] The fiber coupler is a device for detachable connection between optical fibers. The so-called coupling refers to precisely butting the two end faces of the optical fibers by the fiber coupler to ensure that the light energy output by the transmitting optical fiber can be coupled into the receiving optical fiber to the maximum extent.

[0033] The signal input port A and the signal output port B are coupled with the light source (1) and the receiver (13) respectively by the first fiber coupler (16) and the second fiber coupler (17). For example Figure 6 a, the signal input port A and the signal output port B can be coupled with the light source and the receiver by the adapter. If the base is made of metal material, it can be processed and manufactured by the injection molding method.

[0034] In the embodiment, as shown in Figure 7 a, the particle guide pipe (8) is fixed at the through hole C of the base by the welding flange (15); the particle guide pipe (8) is directly connected with the gas transmission pipeline, and the gas transmission pipeline is used for conveying the gas containing particles. Alternatively, as shown in Figure 7 b, the particle guide pipe (8) is fixed at the through hole C of the base by the metal pipe fixing support (14); the particle guide pipe (8) is connected with the airflow guide pipe, the airflow guide pipe is connected with the gas transmission pipeline, and the airflow guide pipe is used for inputting the gas containing particles in the gas transmission pipeline into the particle guide pipe (8). On the one hand, the particle guide pipe can be fixed on the base by the metal pipe fixing support, and the measured gas can be introduced by being connected with the airflow guide pipe to implement the particle detection. On the other hand, the double-flange fixing structure can also be used to directly connect with the gas transmission pipeline to perform the online monitoring of the particle concentration. When the particle guide pipe (8) is fixed, the light transmission hole is aligned with the optical path to prevent part of the light beam from being blocked and reduce the scattered light intensity.

[0035] In this embodiment, the light emitted by the light source (1) is parallelly injected into the optical measuring body along the horizontal direction after the beam shaper (2), and the optical measuring body includes: a part where the incident light coincides with the measured gas with particles; and a particle conduit (8) for inputting the sample to be tested into the optical measuring body.

[0036] Wherein, the first diaphragm (3) is located at the object distance x of the converging lens group (4), the focal length of the converging lens group (4) is f1, the aperture radius of the first diaphragm (3) is D1 and the divergence angle is θ1, the divergence angle of the refracted light is θ1', the focal length of the beam expanding lens group (6) is f2, the width of the light before the beam expanding lens group (6) is D2, and D2=2D2', D2' represents the width of the light after beam expansion.

[0037] For example Figure 1 As shown, the light beam passing through the beam shaper (2) has a certain divergence angle, and the spot radius of the outgoing light beam also cannot meet the width requirement of the optical measuring body, so a diaphragm is added to limit the outgoing light beam. Specifically, the light converging lens group (4) is placed after the first diaphragm (3) to converge the light beam. The object distance of the light converging lens group (4) is x, the first diaphragm is placed at x to determine the size of its image, and the aperture radius of the first diaphragm is D1, so that the spot radius at x is D1, and the divergence angle is θ1. The focal length of the converging lens group (4) is f1, and the divergence angle of the refracted light is θ1'. Therefore, the object distance x can be obtained according to the lens imaging formula of the paraxial optical system.

[0038]

[0039]

[0040] Wherein, l is the object distance, l' is the image distance, D is the object height, D' is the image height, and x is the object distance. Therefore, the following formula is obtained by solving the equation set:

[0041]

[0042]

[0043] After the light path is converged by the converging lens group (4), the incident light still has a small divergence angle. If parallel light is required, a beam expanding lens group (6) is placed to expand the converged light beam, so that the outgoing light is parallel light. However, due to the width requirement of the optical measuring body of 50-100 microns, a second diaphragm is placed at the focal point of the collimating lens group to adjust the size of the incident light spot.

[0044] In order to obtain a detection area with a certain width, the focal length of the beam expander lens group (6) should be f2, and the light width D2' after expansion, and then the light width D2 before the beam expander lens group (6) is calculated from D2', i.e. the size of the aperture stop is D2, and the aperture stop is placed at the focal point of the double concave lens, so that a parallel light with a light width of D2' can be obtained.

[0045] According to the formula:

[0046]

[0047]

[0048] Where the incident angle of the beam expansion part is unknown, but the exit angle of the light convergence part is equal to the incident angle of the beam expansion part, i.e. θ1' = θ2, and A'B' is the image height AB is the size of the light spot on the convergence lens group O is the intersection of the optical path and the principal axis, so according to the formula and the method of similar triangles, θ2 can be obtained:

[0049]

[0050]

[0051] AB = D + x × tan θ

[0052]

[0053] By combining the above formula, we get:

[0054] D2 = 2D2'

[0055]

[0056] According to the above formula, the size of D2 and f2 can be obtained.

[0057] Specifically, the light emitted by the light source (1) has a wavelength range of 780-1100 nm. The components of the multi-reflection light path system (7) in the scattered light path system include two sets of plane mirrors (7-1), a spherical mirror (7-2), two off-axis parabolic mirrors (7-3), and a light trap (9). The spherical mirror (7-2) and the two off-axis parabolic mirrors (7-3) constitute a curved mirror. The spherical mirror (7-2), the plane mirror (7-1), and the off-axis parabolic mirror (7-3) can all be prisms. The vertex of the spherical mirror (7-2) is directly above the optical measurement body, and the two off-axis parabolic mirrors (7-3) are symmetrically placed at 30° and -30°. This arrangement ensures that the focal point of the curved mirror coincides with the optical measurement body. The two sets of plane mirrors (7-1) are symmetrically installed at angles of 45° and -45°. The distance between the two off-axis parabolic mirrors (7-3) is greater than D, where f represents the distance from the vertex of the spherical mirror (7-2) to the optical measurement body, which represents the central angle of the spherical mirror (7-2).

[0058] For example, the scattered light path system designed in this embodiment consists of a multi-reflection light path system and a scattered light receiving system. The incident light beam enters the optical measurement body and is transmitted to the receiver after passing through the scattered light path for reception. The intensity of scattered light is small, which may result in the pulse signal generated by the smallest particles being smaller than the detection threshold, causing the detected particles to be ignored, thereby affecting the resolution of the system. Therefore, a scattered light reflection system is added to concentrate more scattered light to enhance the light intensity collected by the receiver. In the scattered light reflection system, multiple angles of scattered light are collected through a multi-reflection light path. For example, Figure 2As shown, the multi-reflection optical path system mainly consists of a plane mirror (7-1), a spherical mirror (7-2), an off-axis parabolic mirror (7-3), and a light trap (9). The spherical mirror (7-2) and the off-axis parabolic mirror (7-3) constitute a curved mirror. Alternatively, the spherical mirror (7-2), the plane mirror (7-1), and the off-axis parabolic mirror (7-3) can all be prisms. The vertex of the spherical mirror (7-2) is placed directly above the optical measurement body, and the centers of the two off-axis parabolic mirrors (7-3) are symmetrically placed at 30° and -30°. The off-axis mirrors have a spacing greater than D to avoid blocking the optical path. Therefore, the off-axis mirrors are symmetrically placed at 30° and -30°. The focal point of the curved mirror (the general term for the off-axis parabolic mirror and the spherical mirror) coincides with the optical measurement body to ensure that the scattered light is converted into parallel light after being reflected by the curved mirror, facilitating the convergence of the scattered light by the converging lens group (12). However, since the direction of the scattered light after passing through the off-axis parabolic mirror is opposite to that of the converging lens group, the two plane mirrors (7-1) are used to change the direction of the light reflected by the off-axis parabolic mirror (7-3), so that all the reflected scattered light is collected by the receiver (13) after being focused, generating a pulse signal. The convex-concave lens group can reduce the diameter of the scattered light, and the third diaphragm can filter out stray light. Finally, the scattered light converging lens group converges the light. The light trap (9) reflects the light beams that do not scatter to the outside of the optical system, thereby avoiding interference of the excess light beams with the light pulse. The two plane mirrors (7-1) are symmetrically installed at angles of 45° and -45°.

[0059] Let the central angle of the spherical mirror (7-2) be The focal length, i.e., the distance from the vertex of the spherical mirror (7-2) to the optical measurement body, is f.

[0060] According to the formula:

[0061]

[0062]

[0063] The diameter of the spherical mirror is:

[0064] Therefore, to avoid blocking the optical path, the spacing between the two off-axis parabolic mirrors (7-3) is greater than D.

[0065] Since the focal length of the lens used for focusing function (which can be referred to as focusing lens) is proportional to the size of the focal point, and the size of the focal point directly affects whether the receiver can more accurately collect the scattered light intensity, a lens with smaller focal length is selected as much as possible under the condition of meeting the requirements. Among them, D is the diameter of the incident light, and d is the diameter of the light spot. When the diameter of the incident light is constant, the smaller the focal length, the smaller the diameter of the light spot.

[0066] In this design, the beam diameter of the scattered light after passing through the double reflection optical path is relatively large. Two convex and concave lens groups with different focal lengths are used, and their focal points are aligned to reduce the beam diameter. Furthermore, even after the beam diameter is reduced, there is still a certain intensity of stray light affecting the signal-to-noise ratio of the optical sensor; therefore, an aperture is needed to filter out the stray light. Finally, a scattering light converging lens group is used to focus the light path. The substrate can be a metallic substrate or a non-metallic substrate. The material used to manufacture the substrate needs to simultaneously satisfy the characteristics of a low coefficient of thermal expansion and a certain strength, such as metals like copper and iron, ceramics, and glass. The substrate can be manufactured using 3D printing technology. In this embodiment, as... Figure 6 As shown in diagram a, the designed optical components can be encapsulated within a metal or non-metal substrate with a low coefficient of thermal expansion and sufficient strength. Holes are made on the side of the substrate, and screws are used to secure and adjust the positions of the optical components, ensuring coaxial encapsulation. Epoxy resin or other adhesives are then used to seal the optical components, ensuring the airtightness of the entire cavity and preventing dust from entering the sensor and obstructing the optical path.

[0067] In this embodiment, the particle conduit (8) has four glass windows. The two symmetrically installed glass windows at the top and bottom are used for scattered light to pass through, and the two symmetrically installed glass windows on the left and right are used for incident light to pass through. The size of the two symmetrically installed glass windows at the top and bottom is larger than that of the two symmetrically installed glass windows on the left and right. The two symmetrically installed glass windows at the top and bottom are made of high-temperature and high-pressure resistant polymer PAM board special industrial transparent material; the two symmetrically installed glass windows on the left and right are made of polymer transparent material.

[0068] The tube body (also referred to as the tube matrix) of the granular conduit (8) is made of an iron-nickel alloy with a nickel content of 32% and a coefficient of thermal expansion of 0.7 × 10⁻⁶. -6 m / ℃.

[0069] In this embodiment, as Figure 8 As shown, the process of particle detection using the particle detection sensor includes: inputting gas containing particles from the gas transmission pipeline into the particle conduit (8); activating the light source (1), and then receiving the scattered light transmitted through the glass window on the particle conduit (8) via the receiver (13) to obtain the scattered light signal, and then converting the scattered light signal into a voltage pulse signal; measuring the particle size and number of particles based on the amplitude and count of the voltage pulse signal.

[0070] The particle-containing gas in the gas transmission pipeline is input into the particle guide pipe (8) by connecting a gas flow guide pipe to the gas transmission pipeline, and the particle guide pipe (8) is fixed at the through hole C of the metal base by a metal pipe fixing support (14), and the particle guide pipe (8) is connected to the gas flow guide pipe; or the particle guide pipe (8) is directly connected to the gas transmission pipeline, and the particle guide pipe (8) directly obtains the particle-containing gas from the gas transmission pipeline.

[0071] For example, since the measured object is high-temperature and high-pressure gas, the gas cannot be in direct contact with the cavity formed by the spherical mirror (7-2), so the particle guide pipe (8) is needed to guide the high-temperature and high-pressure gas. The particle guide pipe (8) is composed of a glass window and a metal base. Figure 3 The particle guide pipe (8) has four windows, and the upper and lower windows allow scattered light to pass through, and the left and right windows allow incident light to pass through. The windows and the metal base are sealed with graphite, and the radial compression force generated between the windows and the base makes the filler adhere to the shaft surface to prevent medium leakage. The particle guide pipe (8) is kept at a certain distance from the three curved mirrors (including a spherical mirror and two off-axis parabolic mirrors. Since the surfaces of the three mirrors are non-planar, they can also be called curved mirrors) to ensure that the total angle of the collected scattered light, i.e. the sum of αβγ in the formula (1) is 150°. In addition, on the one hand, in order to maximize the angle of the scattered light received by the curved mirrors (one spherical mirror and two off-axis parabolic mirrors), the upper and lower windows of the particle guide pipe (8) are larger than the left and right windows. Figure 3

[0072] For large glass windows, high-temperature and high-pressure resistant high-molecular polyamide special industrial transparent materials with extremely low thermal expansion coefficients are used, which can still maintain the required mechanical strength under high pressure, not only have good dimensional stability, but also ensure the light transmittance of the glass window. For small glass windows, the pressure is smaller, and if the thickness is the same as that of the large window, not only the material is wasted and the cost is increased, but also the thickness of the window is too large to cause the translation of parallel light and change the direction of light propagation. Therefore, the small window uses a high-molecular transparent material with lower mechanical strength to reduce the thickness of the glass window. On the other hand, an iron-nickel alloy with a nickel content of 32% and a high strength, hardness and toughness is used, and the thermal expansion coefficient is 0.7×10 -6 ​Materials with a temperature resistance of m / ℃ are used as the substrate for the conduit. Furthermore, high-temperature resistant insulating coatings that can impede heat flow can be used to insulate the inner and outer walls of the high-strength, pressure-resistant substrate. For example, ZS-1 high-temperature insulating coating, with a temperature resistance of 2000 degrees Celsius, is made from a specially synthesized inorganic silicate solution, aluminum silicate fiber, heat-reflective materials, and selected hollow ceramic microspheres. The coating is an inorganic single-component, non-toxic, and harmless material. The coating has an extremely low thermal conductivity of only 0.03 W / mK, resulting in significant heat insulation effects. Under certain thickness conditions, the insulation efficiency can reach approximately 90%. The overall structure of the coating is equivalent to creating a thermos flask-like heat insulation mechanism. The air inside the hollow ceramic microspheres added to the coating will not generate heat convection after being heated at high temperatures. The tightly packed hollow ceramic microspheres also have a three-dimensional air layer between them, further preventing heat convection. Inorganic film-forming materials with relatively low thermal conductivity serve as the support for the coating, together constructing an insulating shielding layer composed of a static air layer and the inorganic film-forming materials. Heat-reflective materials are added as auxiliary fillers, thus bringing the coating's thermal conductivity close to that of a vacuum, achieving effective heat insulation.

[0073] Furthermore, such as Figure 4 The diagrams shown illustrate the installation of flange-fixed and bracket-fixed particle conduits. On one hand, a metal pipe bracket (14) can be used to fix the particle conduit (8) to a metal substrate. The gas to be measured is introduced through connection with the gas flow conduit for particle detection. The gas flow conduit's function is to introduce gas from the gas transmission pipeline into the particle conduit. On the other hand, a double-welded flange (15) can be used to directly connect the structure to the gas transmission pipeline for online monitoring of particulate matter concentration. When fixing the conduit, the glass window is aligned with the optical path to prevent partial beam obstruction and reduced scattered light intensity. By measuring the scattered light signal of a single particle, it is converted into a voltage pulse signal. The amplitude and count of this pulse signal are used to achieve online measurement of parameters such as particle size and number. Simultaneously, particle concentration information is obtained by combining parameters such as particle density.

[0074] The current commercial optical particle counters use ordinary optical lens and non-temperature and pressure resistant structure design, so its application conditions and fields will be greatly limited, widely used in powder manufacturing and dust removal equipment design field under normal temperature and pressure conditions. For the particle detection needs under very high temperature and pressure conditions, researchers mainly focus on high temperature and pressure and high pressure conditions. For example, for high temperature and pressure conditions, domestic and foreign scholars based on the temperature requirements of optical particle counter, using the cooling-on-line method, the detection gas temperature is cooled to the maximum operating temperature allowed by the detection instrument, to realize the measurement of particle size and concentration parameters. However, this method has some problems, on the one hand, due to the cooling process, the originally gaseous substances at high temperature will gradually condense and produce harmful substances; on the other hand, under high temperature and pressure conditions, particles exhibit liquid properties, their shape is spherical like droplets, when the temperature decreases, particles condense to form irregular solids, causing detection errors. For normal temperature and high pressure conditions, it is mainly concentrated in the field of high pressure natural gas transmission, researchers improve the pressure resistance of optical particle counter by using high pressure resistant glass. However, while meeting the pressure resistance performance, due to the differences between the characteristics of gas medium under normal temperature and high pressure conditions and normal temperature and pressure, as the detection pressure conditions increase, the optical measurement body of optical particle counter increases, causing the degradation of instrument detection performance. Therefore, it is necessary to improve the optical sensor to have good temperature and pressure resistance, to adapt to the application conditions of temperature 100-1500℃ and pressure 1-10MPa.

[0075] (1) To realize the optical accurate measurement of particles under high temperature and pressure conditions, in addition to breaking through the temperature and pressure resistance of the detection device, it is still necessary to solve the problem of fluctuation of detection performance of optical particle counter caused by changes of working conditions. Because the volume of gas expands at high temperature and compresses at high pressure, the two have opposite effects, resulting in more variable optical properties of gas compared to high temperature and pressure and normal temperature and pressure, so on this basis, the optical system of the optical particle counter uses focused light mode, and the beam transmission performance will be seriously affected by the temperature and pressure of the gas.

[0076] (2) The light beam in the optical system of the optical particle counter is Gaussian beam, the energy is maximum at the center of the cross section and minimum at the edge, showing the characteristics of uneven light energy distribution. Due to this problem, the voltage signal corresponding to the scattered light signal of the particles cannot meet the standard characteristics of effective information screening regulations, and measurement errors of particle count and particle size parameters will occur in measurement. At the same time, it will also cause the resolution of the detection system to decrease.

[0077] Based on the problems existing in current optical particle counters, and to address the industrial demand for particle optical detection technology under high temperature and high pressure conditions, this invention proposes a design for a particle optical detection sensor applicable to such conditions. Primarily based on light scattering theory, it measures the scattered light signal of a single particle, converts it into a voltage pulse signal, and uses the amplitude and count of this pulse signal to achieve online measurement of parameters such as particle size and number. Simultaneously, it combines this with parameters such as particle density to obtain particle concentration information. The specific design features the following characteristics: the optical sensor has excellent temperature and pressure resistance, and the application conditions are: temperature 100–1500℃, pressure 1–10... MPa; The particle optical detection sensor is universally applicable under different temperature and pressure conditions, solving the problem of performance fluctuations in optical particle counters caused by changes in operating parameters. In particular, it solves the problem of increased optical measurement volume caused by changes in gas refractive index under high pressure and high temperature conditions, maintaining the sensor's design measurement accuracy. It adopts a dual-reflection optical path system to collect scattered light from multiple angles, improving the minimum detection particle size of micro and nano particles for the optical detection sensor. The addition of optical elements to the optical system eliminates the Gaussian distribution of beam energy, making the cross-sectional light energy distribution of the optical measurement volume area uniform, expanding the detection and screening capabilities of single-particle scattered light signals, and improving the detection accuracy of the optical sensor.

[0078] In summary, the solution provided in this embodiment offers a narrower optical detection area in the optical detection system, allowing particles in the gas to pass through the detection area as individual particles or smaller particle clusters. Figure 5 As shown, this can improve the detection accuracy of the system; and by shaping the optical path, the incident light enters the detection area in a parallel manner, effectively avoiding the influence of refractive index caused by high temperature and high pressure; in addition, by adding a curved reflector (7-2) in the detection area to expand the receiving angle of the scattered light, the intensity of the received scattered light is enhanced, thereby improving the reliability, stability and accuracy of the output signal.

[0079] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the device embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The above descriptions are merely specific embodiments 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 scope of the technology 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 particle detection sensor, characterized by, The utility model relates to a kind of optical particle detection device, including: Base, incident light path system and scattering light path system; The incident light path system is used to receive the light emitted by light source (1), and is shot into the scattering light path system;Light is finally shot into receiver (13) after passing through the scattering light path system; The base is internally provided with light transmission through hole, and the light transmission through hole is aligned with incident light path, and particle guide pipe (8) is fixed on the base; Signal input port A and signal output port B are further provided on the base, first fiber coupler (16) is installed at signal input port A, first fiber coupler (16) is connected with light source (1), second fiber coupler (17) is installed at signal output port B, and second fiber coupler (17) is connected with receiver (13); Signal input port A and signal output port B are coupled with light source (1) and receiver (13) respectively by first fiber coupler (16) and second fiber coupler (17). The light emitted by light source (1) is parallelly shot into optical measuring body along horizontal direction after passing through beam shaper (2), and the optical measuring body includes: the part where incident light coincides with the measured gas containing particles;Test sample is input into particle guide pipe (8), and is introduced into the optical measuring body through particle guide pipe (8); The first diaphragm (3) is located at the object distance of the converging lens group (4) , wherein the focal length of the converging lens group (4) is , the aperture radius of the first diaphragm (3) is and the divergence angle is , the divergence angle of the refracted light is , the focal length of the beam expanding lens group (6) is , the light width before the beam expanding lens group (6) is , and , , represents the light width after the beam expansion. The wavelength range of the light emitted by light source (1) is 780~1100nm.

2. The particle detection sensor of claim 1, wherein, Four glass windows are provided on particle guide pipe (8), and the upper and lower two symmetrically installed glass windows are used for the passage of scattered light, and the left and right two symmetrically installed glass windows are used for the passage of incident light, and the size of the upper and lower two symmetrically installed glass windows is greater than that of the left and right two symmetrically installed glass windows.

3. The particle detection sensor of claim 1, wherein, The components of multi-reflection light path system (7) in the scattering light path system include: two groups of plane mirrors (7-1), spherical mirror (7-2), two off-axis parabolic mirrors (7-3) and light trap (9), and spherical mirror (7-2) and the two off-axis parabolic mirrors (7-3) form a curved mirror; The vertex of spherical mirror (7-2) is located directly above the optical measuring body, and the two off-axis parabolic mirrors (7-3) are symmetrically placed at 30° and-30°. The two groups of plane mirrors (7-1) are symmetrically installed, and the installation angles are 45° and-45° respectively.

4. The particle detection sensor of claim 3, wherein, The distance between the two off-axis parabolic mirrors (7-3) is greater than D, wherein, represents the distance from the vertex of the spherical mirror (7-2) to the optical measurement body, represents the central angle of the spherical mirror (7-2).

5. The particle detection sensor of claim 4, wherein, The upper and lower two symmetrically installed glass windows are made of high-temperature and high-pressure resistant high-molecular polyamide plate special industrial transparent material, and the left and right two symmetrically installed glass windows are made of high-molecular transparent material. The tube of the granule conduit (8) is made of iron-nickel alloy with 32% nickel content and has a thermal expansion coefficient of 0.7 x 10 -6 m / °C.

6. The particle detection sensor of any one of claims 1-5, wherein, A particle detection method under harsh working conditions is executed by the particle detection sensor, including: The gas containing particles in the gas transmission pipeline is input into particle guide pipe (8); Start light source (1), then receive the scattered light transmitted through the glass window provided on particle guide pipe (8) by receiver (13), obtain scattered light signal, and then convert the scattered light signal into voltage pulse signal; According to the amplitude and count of the voltage pulse signal, the particle size and the number of particles are measured.

7. The method of claim 6, wherein, The gas containing particles in the gas transmission pipeline is input into particle guide pipe (8), including: The gas flow conduit is connected to the gas transmission pipe, and the gas containing particles in the gas transmission pipe is input into the particle conduit (8) through the gas flow conduit, wherein the particle conduit (8) is fixed at the through hole C of the base body by the metal pipe fixing support (14), and the particle conduit (8) is connected to the gas flow conduit; Alternatively, the particle conduit (8) is directly connected to the gas transmission pipe, and the particle conduit (8) directly obtains the gas containing particles from the gas transmission pipe.

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