A laser methane sensor waterproof structure

Abstract

The application provides a kind of laser methane sensor waterproof structure, comprising: in the order of air flow direction: air inlet, filter component, laser light path cavity;The filter component includes: drying gas chamber, drying agent is provided in the drying gas chamber;The laser light path cavity is isolated with drying gas chamber by waterproof air-permeable membrane.This application increases drying agent on the basis of traditional laser methane sensor, and adds the drying gas chamber of drying agent, drying agent has strong adsorption capacity to water vapor in air, which can filter out most of the water vapor in the air, so as to ensure the dryness of the air entering the laser methane sensor, greatly reduce the frequency of water vapor pollution laser methane sensor light path, reduce the equipment maintenance frequency, reduce the artificial maintenance cost;At the same time, drying agent has repeatability, can save cost.

Description

Technical Field

[0001] This utility model relates to the field of gas sensing equipment technology, specifically a waterproof structure for a laser methane sensor. Background Technology

[0002] A laser methane sensor is a sensor that uses laser spectroscopy technology to achieve high-precision gas detection. It is a methane detection device based on tunable absorption spectroscopy technology. It mainly utilizes the selective absorption characteristics of gas molecules on laser light, and calculates the gas concentration by analyzing the laser light after passing through the gas by analyzing the wavelength of the emitted light from the sensor.

[0003] Existing technologies suffer from water vapor contamination of the laser sensor's optical path during actual use of laser methane alarms or valve well detectors. Due to high temperature and humidity in actual operating environments, a significant amount of water vapor is present. This water vapor propagates into the laser methane sensor. Because water vapor molecules are small, they easily pass through the waterproof and breathable membrane on traditional laser methane sensors. The water vapor condenses into liquid droplets on the detection optical path, contaminating it and triggering an alarm for optical path contamination. The traditional solution is to manually disassemble the laser methane sensor on-site, clean the detection optical path, and then reinstall it.

[0004] This traditional laser methane sensor structure has many shortcomings in addressing the problem of water vapor contamination of the optical path. Its detector optical path contamination fault alarm frequency is relatively high, equipment maintenance frequency increases, and manual maintenance costs are high. Utility Model Content

[0005] The purpose of this invention is to provide a waterproof structure for a laser methane sensor, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A waterproof structure for a laser methane sensor includes: an air inlet, a filter assembly, and a laser optical path cavity arranged sequentially along the airflow direction;

[0008] The filter assembly includes: a drying chamber containing a desiccant; the laser optical path cavity is isolated from the drying chamber by a waterproof and breathable membrane.

[0009] Optionally, the filter assembly further includes a stainless steel sintered layer, wherein, along the airflow direction, the airflow sequentially passes through the stainless steel sintered layer, the desiccant, the drying chamber, and the waterproof and breathable membrane, and flows into the laser optical path cavity.

[0010] Optionally, a detachable base is also included, with the drying chamber located within the base.

[0011] Optionally, the desiccant is a silica gel particle desiccant or a molecular sieve desiccant.

[0012] Optionally, the drying chamber is an inverted conical cavity.

[0013] Optionally, the ratio of the inlet diameter D1 to the outlet diameter D2 of the drying chamber satisfies:

[0014] Optionally, a guide groove is formed on the conical surface of the inverted conical cavity.

[0015] Optionally, the cone angle of the drying chamber is in the range of 12°-18°.

[0016] Optionally, the height of the drying chamber is not less than 5 mm.

[0017] Optionally, the air inlet is tilted, with the tilt angle ranging from 25 to 40°.

[0018] Compared with existing technologies, this application provides a waterproof structure for a laser methane sensor, comprising: an air inlet, a filter assembly, and a laser optical path cavity arranged sequentially along the airflow direction; the filter assembly includes a drying chamber containing a desiccant; the laser optical path cavity is isolated from the drying chamber by a waterproof and breathable membrane. This application adds a desiccant and a drying chamber to the traditional laser methane sensor. The desiccant has a strong adsorption capacity for moisture in the air, filtering out most of the moisture, thus ensuring the dryness of the air entering the laser methane sensor. This significantly reduces the frequency of moisture contamination of the laser methane sensor's optical path, reduces equipment maintenance frequency, and lowers labor costs. Simultaneously, the desiccant is reusable, saving costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal structure of the waterproof vapor-proof structure of a laser methane sensor.

[0020] Figure 2 This is a schematic diagram of the waterproof structure of a laser methane sensor.

[0021] In the diagram: 1. Laser optical path cavity; 2. Drying chamber; 3. Desiccant; 4. Waterproof and breathable membrane; 5. Base; 6. Stainless steel sintered layer. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Furthermore, the elements in this invention are referred to as being "fixed to" or "set on" another element, which may be directly on the other element or may also include an intervening element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or may also include an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0024] Please see Figures 1-2 This utility model provides a waterproof structure for a laser methane sensor, comprising: an air inlet, a filter assembly, and a laser optical path cavity arranged sequentially along the airflow direction; the filter assembly includes: a drying chamber, in which a desiccant is disposed; the laser optical path cavity and the drying chamber are isolated by a waterproof and breathable membrane.

[0025] In this embodiment, the waterproof and breathable membrane can be made of ePTFE (expanded polytetrafluoroethylene) material with a pore size of 0.2μm, serving as the final barrier against moisture adsorption in the air entering the laser optical path cavity. The inner wall of the laser optical path cavity is polished to Ra≤0.1μm, which can effectively reduce light scattering.

[0026] In this embodiment, the laser methane sensor mainly consists of a laser source, a sample chamber, and a detector. The following is a detailed description of each component:

[0027] Laser source: The laser source is an important component of the laser methane sensor, and its function is to emit laser light of a specific wavelength. The wavelength of laser light absorbed by methane molecules is related to their molecular structure; each molecule absorbs a different wavelength. Therefore, the specific wavelength of laser light emitted by the laser source ensures that the subsequent absorption process by methane molecules occurs accurately, thus providing a basis for the precise calculation of methane molecule concentration.

[0028] Sample Chamber: The sample chamber is the space through which methane-containing gas enters and through which the laser beam passes. When the laser beam passes through the methane-containing gas, some of the laser light is absorbed by the methane molecules; this process occurs within the sample chamber.

[0029] Detector: The detector is used to measure the absorbed laser energy. It receives the laser energy remaining after passing through the sample chamber, and by measuring the absorbed laser energy and applying Lambert-Beer's law (which describes the absorption of light in a homogeneous medium), the concentration of methane in the gas can be calculated.

[0030] In this embodiment, the air inlet is used to supply sample gas into the laser optical path cavity. As a preferred embodiment, the air inlet is inclined with an inclination angle ranging from 25 to 40° to prevent gas from directly entering the laser optical path cavity. This slows down the flow rate of gas entering the filter assembly, allowing the filter assembly to filter the incoming gas more thoroughly.

[0031] In this embodiment, the above-mentioned filter component further includes: a stainless steel sintered layer, and along the airflow direction: the airflow passes sequentially through the stainless steel sintered layer, the desiccant, the drying air chamber, and the waterproof and breathable membrane, and flows into the laser optical path cavity.

[0032] The aforementioned stainless steel sintered layer can be 316L stainless steel, with 50μm pores to intercept particulate matter and a porosity of 45%, used for primary filtration of the gas entering the laser methane sensor. The aforementioned drying chamber is located within the base; the drying chamber is an inverted conical cavity, which can increase the flow rate, reduce water vapor retention, and effectively prevent water accumulation.

[0033] In a preferred embodiment, the ratio of the diameter D1 at the inlet end of the drying chamber to the diameter D2 at the outlet end satisfies: This is more conducive to increasing the flow rate and reducing water vapor retention, which can effectively prevent water accumulation; the guide groove is opened on the conical surface of the inverted conical cavity, which can effectively improve the uniformity of airflow;

[0034] Specifically: the straight-through gas chamber is prone to generating eddies, which can easily cause uneven water vapor adsorption and fluctuations in methane concentration detection; the spiral groove forces the gas to move along the spiral line, controlling the Reynolds number at Re < 2000 (laminar critical value).

[0035] In this embodiment, the cone angle of the drying chamber is in the range of 12°-18°. Specifically: when the cone angle is >18°: airflow separation generates eddies (Reynolds number Re>2500), resulting in: methane concentration detection fluctuations (±7% error) and localized water vapor accumulation (humidity difference>20%); when the cone angle is <12°: the chamber is too long, and the pressure loss increases (ΔP>0.8kPa);

[0036] Experimental verification data

[0037] Test conditions: 1.5% methane, 90% RH, flow rate 1.2 L / min.

[0038] 10 9.2 ±2.1 1800 15 7.5 ±0.8 3500 20 8.1 ±3.5 1200

[0039] As can be seen, the cone angle range of the drying chamber provided in this application is 12°-18°, which can better control the Reynolds number, avoid the generation of eddies, make the gas adsorption more uniform, reduce water vapor retention, and effectively prevent water accumulation.

[0040] In this embodiment, the height of the drying chamber is not less than 5 mm. As a preferred embodiment, the drying chamber buffer layer (spacing 5-8 mm) can effectively buffer the pressure of the desiccant expansion.

[0041] In one specific embodiment, the desiccant is a silica gel particle desiccant or a molecular sieve desiccant; in this embodiment, the volume V of the drying chamber and the mass m of the desiccant satisfy: V / m = 2.5 ± 0.5 cm³. 3 / g; the desiccant is preferably silica gel granules, and as a preferred embodiment, the silica gel granules have a particle size of 2mm and a bulk density of 0.65g / cm³. 3 It can effectively adsorb moisture in the air; because silica gel particles have a strong adsorption capacity for moisture in the air, they can filter out most of the moisture in the air, thus ensuring the dryness of the air entering the laser methane sensor.

[0042] In this embodiment, a four-layer adsorption system is designed: the first layer is a sintered stainless steel layer (50μm pores to intercept particulate matter), the second layer is a dynamic drying layer (silica gel + molecular sieve composite filling), the third layer is a buffer gas chamber (conical diffuser structure), and the fourth layer is a nano-waterproof membrane (0.2μm pore size). By adopting the technical solution of this application, the frequency of water vapor pollution in the laser methane sensor optical path can be greatly reduced, the number of equipment maintenance operations can be reduced, and labor maintenance costs can be saved; at the same time, the silica gel particle desiccant is reusable.

[0043] The water vapor-proof structure of the laser methane sensor provided in this application, after actual testing, has been able to perform the detection work of laser methane alarms or valve well detectors very well, and has greatly reduced the frequency of water vapor contamination of the laser methane sensor, thus meeting the usage requirements.

[0044] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A waterproof structure for a laser methane sensor, characterized in that, include: Arranged sequentially along the airflow direction: air inlet, filter assembly, laser optical path cavity; The filter assembly includes: a drying chamber, wherein a desiccant is disposed in the drying chamber; The laser optical path cavity is isolated from the drying air chamber by a waterproof and breathable membrane.

2. The waterproof structure for the laser methane sensor according to claim 1, characterized in that, The filter assembly further includes a stainless steel sintered layer. Along the airflow direction, the airflow passes sequentially through the stainless steel sintered layer, the desiccant, the drying chamber, and the waterproof and breathable membrane, and flows into the laser optical path cavity.

3. The waterproof structure for the laser methane sensor according to claim 2, characterized in that, It also includes a detachable base, with the drying chamber located inside the base; the stainless steel sintered layer is disposed at the bottom of the base, below the drying chamber.

4. The waterproof structure for the laser methane sensor according to claim 1, characterized in that, The desiccant is a silica gel particle desiccant or a molecular sieve desiccant.

5. The waterproof structure for the laser methane sensor according to claim 1, characterized in that, The drying chamber is an inverted conical cavity.

6. The waterproof structure for the laser methane sensor according to claim 1, characterized in that, The ratio of the diameter D1 at the inlet end to the diameter D2 at the outlet end of the drying chamber satisfies: .

7. The waterproof structure for the laser methane sensor according to claim 5, characterized in that, A flow guide groove is formed on the conical surface of the inverted conical cavity.

8. The waterproof structure for the laser methane sensor according to claim 1, characterized in that, The cone angle of the drying chamber ranges from 12° to 18°.

9. The waterproof structure for the laser methane sensor according to claim 1, characterized in that, The height of the drying chamber is not less than 5 mm.

10. The waterproof structure for the laser methane sensor according to claim 1, characterized in that, The air inlet is tilted, with an tilt angle ranging from 25 to 40°.

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