An oxygen sensor, an oxygen measuring device and a method for a petrochemical tank area

Abstract

The present application discloses an oxygen sensor, an oxygen measuring device and method for a petrochemical tank area, and belongs to the field of sealing measurement of petrochemical tank areas. It includes a shell and a U-shaped detection body; the U-shaped detection body includes a double-material beam and a single-material beam; there are at least two double-material beams, including a base beam and a film layer plated on the upper surface of the base beam, the base beam is made of a first material, and the film layer is made of a second material, and the thermal expansion coefficients of the first material and the second material are different; there are at least two single-material beams, which are made of a third material; the double-material beam and the single-material beam are alternately connected in sequence, and at least two double-material beams are arranged in parallel, and at least two single-material beams are arranged in parallel, and the head end and the tail end are both double-material beams, so that the single-material beam and the double-material beam form a U-shaped shape; the end of the double-material beam at the end that is away from the single-material beam is fixed in the shell; the shell is provided with an inlet and an outlet to allow gas to enter and exit. The present application has high sensitivity, a low detection limit, and a fast response speed.

Description

Technical Field

[0001] The present application relates to the technical field of sealing measurement of petrochemical tank areas, and in particular to an oxygen sensor, an oxygen measurement device and a method for petrochemical tank areas. Background Art

[0002] Petrochemical tank farms are important facilities in the petrochemical industry for storing, transporting and processing raw materials and finished products. Various chemical storage tanks in petrochemical tank farms are connected by pipelines, which are sealed with nitrogen to form gas-connected tanks to reduce the emission of volatile organic compounds in the atmosphere. Each tank stores flammable and explosive substances. Each tank is mechanically connected by physical means, and there is a possibility of leakage at the connection. Once a leak occurs, the entire petrochemical tank farm will be at risk of explosion. Therefore, it is necessary to monitor the nitrogen sealing effect of the connected petrochemical tank farms to prevent accidents.

[0003] Current monitoring methods include visual inspection and gas detection. The visual inspection method uses human eyes to observe the tank area and check whether there is oil, cracks, water accumulation and other phenomena on the surface of the tank body to determine whether there is a leak. However, this method is greatly affected by human factors and it is difficult to detect small leaks. The gas detection method is to detect the presence of flammable gases, toxic gases and other components in the air of the tank area to determine whether there is a leak. Compared with the visual inspection method, it is more accurate. However, due to the presence of nitrogen and other gases in the air, it is difficult to detect leaking gas using existing gas detection methods. At the same time, the risk of accidents caused by smaller gas leaks is relatively high, but the existing gas detection methods have low sensitivity, high detection limits, and slow response speeds. Summary of the invention

[0004] The embodiments of the present application provide an oxygen sensor, an oxygen measuring device and a method for a petrochemical tank area, which can solve the problems of the existing gas detection method for petrochemical tank areas being difficult to detect leaked gas, having low sensitivity, a high detection limit and a slow response speed.

[0005] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0006] In a first aspect, an embodiment of the present invention provides an oxygen sensor, comprising a shell and a U-shaped detection body; the U-shaped detection body comprises a dual-material beam and a single-material beam; there are at least two dual-material beams, comprising a base beam and a film layer plated on the upper surface of the base beam, the base beam is made of a first material, the film layer is made of a second material, and the first material and the second material have different thermal expansion coefficients; there are at least two single-material beams, which are made of a third material; the dual-material beams and the single-material beams are alternately connected in sequence, and at least two of the dual-material beams are arranged in parallel, and at least two of the single-material beams are arranged in parallel, and the head end and the tail end are both the dual-material beams, so that the single-material beam and the dual-material beam form a U-shape; the end of the dual-material beam at the end facing away from the single-material beam is fixed in the shell; the shell is provided with an inlet and an outlet to allow gas to enter and exit.

[0007] In combination with the first aspect, in a possible implementation manner, the first material and / or the third material is polyimide.

[0008] In combination with the first aspect, in a possible implementation manner, the second material is aluminum or silver.

[0009] In combination with the first aspect, in a possible implementation manner, the base beam is a rectangular parallelepiped, and the film layer is plated on one surface of the base beam.

[0010] In combination with the first aspect, in a possible implementation manner, the thickness of the film layer is 200 nm, and the thickness of the base beam is 25 um.

[0011] In combination with the first aspect, in a possible implementation manner, each of the dual-material beams is provided with a through hole.

[0012] In a second aspect, another embodiment of the present invention provides an oxygen measuring device for a petrochemical tank area, comprising the oxygen sensor described above, and also comprising a tunable laser, an optical fiber coupler and a signal processing mechanism; a plurality of the oxygen sensors are respectively arranged on the pipelines of the petrochemical tank area; the tunable laser is connected to the optical fiber coupler; laser is emitted to the film layer of each of the oxygen sensors through the optical fiber coupler; the film layer sides of the plurality of oxygen sensors are connected to the optical fiber coupler through optical fibers; and the optical fiber coupler is connected to the signal processing mechanism.

[0013] In a third aspect, another embodiment of the present invention provides an oxygen measurement method for a petrochemical tank farm, using the above-mentioned oxygen measurement device for a petrochemical tank farm, comprising:

[0014] The plurality of oxygen sensors are respectively arranged on pipelines in the petrochemical tank area;

[0015] Connecting the tunable laser to the optical fiber coupler, wherein the tunable laser transmits laser light of a preset wavelength to the optical fiber coupler;

[0016] The optical fiber coupler emits laser light to the film layer of each oxygen sensor, the laser light and oxygen undergo photothermal absorption effect to generate heat, the dual-material beam absorbs the heat energy and deflects, and the deflection is amplified by the multiple dual-material beams of the U-shaped detection body;

[0017] Connecting the membrane layer sides of the plurality of oxygen sensors to the optical fiber coupler via optical fibers;

[0018] The optical fiber coupler is connected to the signal processing mechanism, and the optical fiber coupler transmits the signal to the signal processing mechanism, and the oxygen concentration in the pipeline is inverted by detecting the displacement of the free end of the dual-material beam.

[0019] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0020] The oxygen sensor provided by the embodiment of the present invention, when actually used, has the end of the dual-material beam at the end facing away from the single-material beam, i.e., the fixed end, fixed in the housing, and then the oxygen sensor is set in the connecting pipeline of the petrochemical tank area. If the pipeline leaks, oxygen will enter the pipeline. The oxygen sensor detects whether oxygen enters the pipeline to indirectly detect whether the pipeline is leaking, thereby indirectly obtaining the nitrogen sealing effect of the pipeline, thereby avoiding the problem that the existing gas detection method is difficult to detect leaking gas due to the presence of nitrogen and other components of gas in the air. By irradiating a laser with a wavelength at the oxygen absorption peak (760nm) on the side of the dual-material beam of the oxygen sensor with a film layer, when there is oxygen at the position of the dual-material beam, the oxygen and the laser undergo a photothermal absorption effect to generate heat, and the dual-material beam absorbs heat energy and deforms, and the concentration of oxygen in the pipeline is inverted by detecting the displacement of the free end of the dual-material beam. A double-material beam and a single-material beam are alternately connected in sequence, and at least two double-material beams are arranged in parallel, and at least two single-material beams are arranged in parallel, and the head end and the tail end are both double-material beams, so that the single-material beam and the double-material beam form a U-shaped structure, which can amplify the deformation of the double-material beam, thereby improving the sensitivity of detection, and can measure the photothermal absorption caused by temperature changes below 0.05°C, that is, the gas volume is small, and the temperature rise is small. It can also be measured, reducing the detection limit and improving the response speed. In the case of a trace leak in the nitrogen injection pipeline, it can also sense the change in oxygen concentration, with high sensitivity, low detection limit, and fast response speed, preventing fire accidents caused by explosions of storage tanks due to leakage in the Unicom pipeline. The oxygen sensor of the embodiment of the present application uses a laser to irradiate the U-shaped detection body, and then guides the signal to the signal processing mechanism through an optical fiber. No circuit is required, and no electric sparks will be generated, thereby ensuring safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a U-shaped detection body provided in an embodiment of the present application;

[0023] Figure 2 A schematic diagram of the structure of an oxygen sensor provided in an embodiment of the present application;

[0024] Figure 3 A schematic diagram of the structure of an oxygen sensor provided in an embodiment of the present application being arranged on a pipeline;

[0025] Figure 4 A comparison chart of simulation results and theoretical results provided in the embodiments of the present application;

[0026] Figure 5 The free end displacement of the first embodiment of the present application;

[0027] Figure 6 The free end displacement of the second embodiment of the present application;

[0028] Figure 7 This is a comparison chart of free end displacement data of a dual-material beam made by using silver or aluminum with a film thickness of 200 nm as the second material for making the film layer in an embodiment of the present application.

[0029] Icon: 1-housing; 2-U-shaped detection body; 21-single material beam; 22-double material beam; 221-base beam; 222-membrane layer; 3-tunable laser; 4-fiber coupler; 5-signal processing mechanism. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the embodiments of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention. The terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0032] Please refer to Figures 1 to 3 As shown, an embodiment of the present invention provides an oxygen sensor, including a housing 1 and a U-shaped detection body 2.

[0033] The U-shaped detection body 2 includes a double-material beam 22 and a single-material beam 21. Figure 1 and Figure 2 As shown, the dual material beams 22 are at least two, such as Figure 1 As shown, the dual-material beam 22 includes a base beam 221 and a film layer 222 plated on the upper surface of the base beam 221. The base beam 221 is made of a first material, and the film layer 222 is made of a second material. The first material and the second material have different thermal expansion coefficients. There are at least two single-material beams 21, which are made of a third material. The first material and the third material can be polymers, and the second material can be metal.

[0034] Continue to refer to Figure 1 and Figure 2 As shown, the double material beam 22 and the single material beam 21 are connected alternately in sequence, and at least two double material beams 22 are arranged in parallel, and at least two single material beams 21 are arranged in parallel, and the head end and the tail end are both double material beams 22, so that the single material beam 21 and the double material beam 22 form a U-shaped shape, thereby reducing the size of the entire U-shaped detection body 2. The end of the double material beam 22 at the end that is away from the single material beam 21 is fixed in the housing 1, and this end serves as a fixed end. The housing 1 is provided with an inlet and an outlet to allow gas to enter and exit.

[0035] The oxygen sensor provided in the embodiment of the present application, on the one hand, the dual-material beam 22 includes a base beam 221 and a film layer 222 plated on the upper surface of the base beam 221, the base beam 221 is made of a first material, and the film layer 222 is made of a second material, the first material and the second material have different thermal expansion coefficients, when the ambient temperature changes, the two materials of the dual-material beam 22 are heated, they will produce different degrees of thermal expansion or contraction, this differential thermal deformation will cause stress distribution inside the dual-material beam 22, the length will increase at different rates, so that the dual-material beam 22 will be deformed by force with temperature changes, resulting in bending deformation and deflection deformation of the dual-material beam 22, and then causing bending deformation and deflection deformation of the overall structure of the U-shaped detection body 2.

[0036] Specifically, the thermal expansion coefficients of the first material and the second material are α1 and α2 respectively, and α1>α2. The thermal expansion coefficient of the entire dual-material beam 22 is uneven. Then, when the dual-material beam 22 is heated, that is, when the temperature of the environment in which the U-shaped detection body 2 is located increases, the first material with a larger thermal expansion coefficient will expand more than the second material with a smaller thermal expansion coefficient. This expansion difference between the two materials will cause tensile stress and compressive stress to be generated inside the dual-material beam 22, causing the beam body to bend and deform. The expansion of the first material is greater than that of the second material, causing the dual-material beam 22 to deflect toward one side of the second material, thereby achieving deflection deformation. Since one end of the dual-material beam 22 is fixed to the housing 1 as a fixed end, and the other end is a free end, this bending deformation and deflection deformation are reflected at the free end of the dual-material beam 22. When the temperature decreases, the first material with a larger thermal expansion coefficient will shrink more than the second material with a smaller thermal expansion coefficient, and stress distribution will also be generated inside the dual-material beam 22, causing the dual-material beam 22 to bend and deform and deflect. By measuring the deformation degree of the dual-material beam 22, the change of the ambient temperature of the U-shaped detection body 2 can be monitored in real time, and can also be used to detect physical quantities or chemical reactions related to temperature changes.

[0037] When the oxygen sensor of the embodiment of the present application measures the nitrogen sealing effect of a petrochemical tank area, the oxygen sensor is set on the pipeline of the petrochemical tank area, and an infrared laser with a wavelength aligned with the oxygen absorption peak (760.3nm) is used to irradiate the membrane layer 222 side of the dual-material beam 22 of the U-shaped detection body 2. The U-shaped detection body 2 absorbs the infrared laser and reacts with oxygen to generate heat flow, which causes the U-shaped detection body 2 to absorb heat and heat up. Due to the different thermal expansion coefficients of the first material and the second material, the free end of the dual-material beam 22 is bent and deflected relative to the fixed end.

[0038] A bi-material beam 22 undergoes a deformation. Specifically, the end of the bi-material beam 22 at the head end that is away from the single-material beam 21 undergoes bending deformation and displacement (displacement refers to the height difference between the height of the bi-material beam 22 after deformation and the height of the plane when it is not deformed), and deflection occurs to produce a deflection angle (deflection angle refers to the angle difference between the bi-material beam 22 after deformation and the angle when it is not deflected), and the single-material beam 21 connected to it does not change, and the displacement and deflection angle are consistent with the bi-material beam 22 at the head end. The next bi-material beam 22 continues to undergo bending deformation and deflection deformation, thereby amplifying the bending deformation and deflection deformation. The next single-material beam 21 still does not change, and so on. The deformation and deflection will be amplified several times if there are several bi-material beams 22.

[0039] The deflection angle deformation of the dual material beam 22 is represented by θ, and the displacement change is represented by S. The total deflection angle of the U-shaped detection body 2 with two dual material beams 22 is θ1+θ2, and the total displacement is S1+S2. And so on. Figure 1 and Figure 2 It can be seen that the U-shaped detection body 2 is provided with nine dual-material beams 22, so the total deflection angle is θ1+θ2+θ3+θ4+θ5+θ6+θ7+θ8+θ9, and the total displacement is S1+S2+S3+S4+S5+S6+S7+S8+S9. The structural design of the U-shaped detection body 2 amplifies the deformation of the dual-material beam 22 caused by the heat generated when the oxygen content is very low, thereby realizing the monitoring of low gas content and high sensitivity temperature.

[0040] The embodiment of the present application utilizes the principle of laser absorption photothermal spectroscopy to measure the concentration of oxygen mixed in by pipeline leakage, and calculates the oxygen concentration through gas photothermal absorption spectroscopy.

[0041] The oxygen sensor provided by the embodiment of the present invention, when actually used, has the end of the dual-material beam 22 at the end facing away from the single-material beam 21, i.e., the fixed end, fixed in the housing 1, and then the oxygen sensor is set in the connecting pipeline of the petrochemical tank area. If the pipeline leaks, oxygen will enter the pipeline. The oxygen sensor detects whether oxygen enters the pipeline to indirectly detect whether the pipeline is leaking, thereby indirectly obtaining the nitrogen sealing effect of the pipeline, thereby avoiding the problem that the existing gas detection method is difficult to detect leaking gas due to the presence of nitrogen and other components of gas in the air. By irradiating a laser with a wavelength at the oxygen absorption peak (760nm) on the side of the dual-material beam 22 of the oxygen sensor with the film layer 222, when there is oxygen at the position of the dual-material beam 22, the oxygen and the laser undergo a photothermal absorption effect to generate heat, and the dual-material beam 22 absorbs heat energy and deforms, and the concentration of oxygen in the pipeline is inverted by detecting the displacement of the free end of the dual-material beam 22. The double material beam 22 and the single material beam 21 are alternately connected in sequence, and at least two double material beams 22 are arranged in parallel, and at least two single material beams 21 are arranged in parallel, and the head end and the tail end are both double material beams 22, so that the single material beam 21 and the double material beam 22 form a U-shaped structure, which can amplify the deformation of the double material beam 22, thereby improving the sensitivity of detection, and can measure the photothermal absorption caused by temperature changes below 0.05°C, that is, the gas volume is small, and the temperature rise is small. It can also be measured, reducing the detection limit and improving the response speed. In the case of a trace leak in the nitrogen injection pipeline, it can also sense the change in oxygen concentration, with high sensitivity, low detection limit, and fast response speed, preventing fire accidents caused by explosions of storage tanks due to leakage of the Unicom pipeline. The oxygen sensor of the embodiment of the present application uses a laser to irradiate the U-shaped detection body 2, and then guides the signal to the signal processing mechanism 5 through an optical fiber. No circuit is required, and no electric sparks will be generated, thereby ensuring safety.

[0042] Among them, by detecting the displacement of the free end of the bi-material beam 22, the specific method of inverting the concentration of oxygen in the pipeline is: first experimentally calibrate the relationship between the displacement and temperature. For example, when the displacement is A1, the temperature is A2, and when the displacement is B1, the temperature is B2, and the relationship between the displacement and temperature is fitted through multiple data. Then, the relationship between temperature and concentration is experimentally calibrated. For example, when the temperature is A2, the concentration is A3, and when the temperature is B2, the concentration is B3, and the relationship between displacement and temperature is fitted through multiple data. It can be known that when the displacement is A1, the concentration is A3, and when the displacement is B1, the concentration is B3, and the corresponding relationship between the displacement and the concentration can be obtained based on the fitting relationship. According to the corresponding relationship between the displacement and the concentration, when the displacement of the free end of the bi-material beam 22 is known during actual measurement, the concentration of oxygen in the pipeline can be inverted.

[0043] Optionally, the first material and / or the third material is polyimide, that is, the first material is polyimide, or the third material is polyimide, or both the first material and the third material are polyimide.

[0044] Preferably, the first material and the third material are both polyimide, so that when manufacturing the U-shaped detection body 2, the U-shaped detection body 2 can be first manufactured by laser cutting using polyimide material, and then a coating layer 222 is formed at the position of the dual-material beam 22, so as to facilitate the manufacture of the U-shaped detection body 2.

[0045] Among polymer materials, polyimide has good high temperature heat resistance and relatively low Young's modulus, good material elasticity and thermal stability, and has good repeatability as a sensor material, thus having good recoverability. In addition, polyimide has a large thermal expansion coefficient, and its sensitivity is greater than that of metal of the same thickness, so that the U-shaped detection body 2 made of polyimide as the first material can have good sensitivity.

[0046] The second material is aluminum or silver. Of course, it can also be gold or other metals. When the first material is polyimide, the thermal expansion coefficients of aluminum, gold or silver differ more from those of polyimide, so that the U-shaped detection body 2 is more sensitive.

[0047] Optionally, the base beam 221 is a rectangular parallelepiped, and a surface of the base beam 221 is coated with a film layer 222. The rectangular parallelepiped is easy to manufacture, and the base beam 221 has multiple planes, which is convenient for coating the film layer 222.

[0048] Furthermore, the thickness of the film layer 222 is 200nm, and the thickness of the base beam 221 is 25um. The thicker the film layer 222 is, the higher the sensitivity of the U-shaped detection body 2 is, but the thicker the coating thickness is, the higher the cost is. The thickness of the film layer 222 is 200nm, which enables the U-shaped detection body 2 to have good sensitivity while being reasonable in cost. The thinner the thickness of the base beam 221 is, the higher the sensitivity of the U-shaped detection body 2 is, but the thickness of the base beam 221 is 25um, which is easy to purchase and has a higher cost performance.

[0049] Firstly, the accuracy of simulation results of Abaqus finite element software is studied.

[0050] Abaqus finite element software is a multi-physics simulation software that can easily simulate the physical process of multiple physical fields coupling. The steps of simulation through Abaqus finite element software are as follows: (1) Pre-processing: mainly construct the geometric model of finite element analysis. (2) Establish finite element model: mainly include defining analysis model, applying constraints, loads, adding material properties, dividing meshes, etc. (3) Solving finite element model: mainly select appropriate methods to solve the equation group so that the results converge, otherwise stop the calculation. (4) Post-processing: mainly analyze the result data and obtain the results and images of finite element analysis.

[0051] In this simulation, a bi-material beam A, the first material used to prepare the base beam 221 is polyimide, and the first material used to prepare the film layer 222 is aluminum (chemical formula: Al). A bi-material beam B, the first material used to prepare the base beam 221 is polyimide, and the second material used to prepare the film layer 222 is silver (chemical formula: Ag). The parameter settings in the Abaqus finite element software are shown in Table 1. Enter the parameters required for the simulation in the Abaqus finite element software, add the solid heat transfer module and the solid mechanics module, enter the load constraints in the thermal stress module, divide the grid for solution, use the Abaqus finite element software to build the simulation geometry model, and calculate the simulation results of temperature rise and displacement.

[0052] Table 1

[0053]

[0054]

[0055] Then Python software is used to calculate the theoretical results of temperature rise and displacement.

[0056] Five temperature points were simulated in the finite element simulation geometric model. Five different temperatures were selected to obtain the free end displacement of the dual-material beam 22. The simulation results established by selecting the first material for preparing the base beam 221 as polyimide with a thickness of 25 μm and the second material for preparing the film layer 222 as silver with a thickness of 100 nm were compared with the theoretical results. The results are shown in Table 2 and Figure 4 shown.

[0057] Table 2

[0058]

[0059] From Table 2 and Figure 4 It can be seen that the simulation results of the free end displacement of the bi-material beam 22 are compared with the theoretical results. It can be seen that as the temperature continues to increase, the free end displacement of the bi-material beam 22 is also increasing. Therefore, when there is oxygen at the position of the bi-material beam 22, the oxygen and the laser undergo a photothermal absorption effect to generate heat, and the bi-material beam 22 absorbs heat energy and deforms. The concentration of oxygen in the pipeline can be inverted by detecting the displacement of the free end of the bi-material beam 22. The above results are the measurement results of simulating a bi-material beam 22, and are also applicable to the U-shaped detection body 2 with at least two bi-material beams 22.

[0060] Through comparative studies, it was found that the errors between the simulation results of Abaqus finite element software and the theoretical results calculated by Python software programming were relatively small, indicating that the simulation model established by Abaqus finite element software has good accuracy and can obtain a relatively accurate simulation model, which can be used as the basis for further simulation modeling and analysis. The credibility of the entire model is high, so the next stage of the finite element software simulation process can be continued.

[0061] Example 1: The first material of the base beam 221 of the dual-material beam 22 is polyimide (thickness is 25um), and the second material of the film layer 222 is silver (thickness is 50nm, 100nm and 200nm respectively). Finite element software simulation is performed to obtain the free end displacement (mm) of the dual-material beam 22 as shown in Table 3 and Figure 5 shown.

[0062] Table 3

[0063]

[0064] From Table 3 and Figure 5 It can be known that the second material used to make the film layer 222 in Example 1 is silver. When the film layers 222 of different thicknesses are simulated, their free end displacement increases with the increase of temperature. When the thickness of the film layer 222 is greater, the free end displacement is greater. This shows that using silver as the second material to make the film layer 222 can cause the bi-material beam 22 to produce a larger deformation. And the greater the thickness of the film layer 222, the more significant the change of the free end displacement with the temperature, and the higher the sensitivity at this time. Therefore, when the thickness of the coating is greater, the change of the free end displacement is greater, and the sensitivity is higher. The above results are the measurement results of simulating a bi-material beam 22, and are also applicable to the U-shaped detection body 2 with at least two bi-material beams 22.

[0065] Example 2: The first material of the base beam 221 of the dual-material beam 22 is polyimide (thickness is 25um), and the second material of the film layer 222 is aluminum (thickness is 50nm, 100nm and 200nm respectively). Finite element software simulation is performed to obtain the free end displacement (mm) of the dual-material beam 22 as shown in Table 4 and Figure 6 shown.

[0066] Table 4

[0067]

[0068] From Table 4 and Figure 6It can be known that the second material used to make the film layer 222 in the second embodiment is aluminum. The film layers 222 of different thicknesses are simulated, and their free end displacement increases with the increase of temperature. When the thickness of the film layer 222 is greater, the displacement of the free end is greater. This shows that using aluminum as the second material to make the film layer 222 can cause the bi-material beam 22 to produce a larger deformation. And the greater the thickness of the film layer 222, the more significant the change of the free end displacement with temperature, and the higher the sensitivity at this time. Therefore, when the thickness of the coating is greater, the greater the change of the free end displacement, the higher the sensitivity. The above results are the measurement results of simulating a bi-material beam 22, and are also applicable to the U-shaped detection body 2 with at least two bi-material beams 22.

[0069] Through Table 3, Figure 5 , Table 4 and Figure 6 From the analysis, it can be seen that when the thickness of the film layer 222 is 200nm, the free end displacement changes significantly. From Table 3 and Table 4, the free end displacement data of the dual-material beam 22 made by using silver or aluminum with a film layer 222 thickness of 200nm as the second material for making the film layer 222 are compared and obtained. Figure 7 ,Depend on Figure 7 It can be seen that when the temperature increases from 0°C to 100°C, the free end displacement of the first material of the film layer 222 made of silver increases from 0 to 0.25 mm, and the free end displacement of the second material of the film layer 222 made of aluminum increases from 0 to 1.45 mm. It can be seen that the free end displacement of the second material of the film layer 222 made of aluminum has a larger change and a higher sensitivity. The above results are the measurement results of simulating a dual-material beam 22, and are also applicable to the U-shaped detection body 2 with at least two dual-material beams 22.

[0070] Furthermore, each bi-material beam 22 is provided with a through hole, so that the sensitivity of the bi-material beam 22 can be improved, and then the sensitivity of the entire oxygen sensor can be improved. Specifically, the inner cavity where the through hole is located is air, and the contact area between the bi-material beam 22 and the air is larger when the light ray passes through the bi-material beam 22. The thermal expansion coefficient at the through hole is different from the thermal expansion coefficient at other places of the bi-material beam 22. When the light passes through the through hole and its surroundings, the heated area of ​​the bi-material beam 22 increases, the vibration of the bi-material beam 22 is greater, the displacement becomes larger, and the sensitivity of the entire bi-material beam 22 is improved.

[0071] Another embodiment of the present invention provides an oxygen measuring device for a petrochemical tank farm, such as Figure 2 and Figure 3 As shown, it includes a plurality of the above-mentioned oxygen sensors, and also includes a tunable laser 3, a fiber coupler 4 and a signal processing mechanism 5.

[0072] like Figure 3As shown, multiple oxygen sensors are respectively arranged on the pipelines of the petrochemical tank area. The tunable laser 3 is connected to the optical fiber coupler 4. The optical fiber coupler 4 emits laser light to the film layer 222 of each oxygen sensor. After the tunable laser 3 emits laser light, it is branched by the optical fiber coupler 4 and then emits laser light to the film layer 222 of each oxygen sensor. The light and gas generate heat energy, and the dual-material beam 22 absorbs the heat and deforms. One side of the film layer 222 of multiple oxygen sensors is connected to the optical fiber coupler 4 through an optical fiber.

[0073] An optical fiber is arranged at a certain distance on the membrane layer 222 side of the dual-material beam 22, and the end face of the optical fiber and the free end of the dual-material beam 22 form an optical fiber Fabry-Perot cavity. When the U-shaped detection body 2 resonates, the cavity length of the optical fiber Fabry-Perot cavity changes, thereby causing the intensity of the reflected interference light to change periodically. The resonance signal of the U-shaped detection body 2 is obtained by demodulating the intensity of the light signal, and finally the concentration of the detected gas is inverted by signal processing.

[0074] The optical fiber coupler 4 is connected to the signal processing mechanism 5. The optical fiber coupler 4 transmits the signal to the signal processing mechanism 5.

[0075] Another embodiment of the present invention provides an oxygen measurement method for a petrochemical tank farm, using the above-mentioned oxygen measurement device for a petrochemical tank farm, comprising:

[0076] Multiple oxygen sensors are installed on pipelines in the petrochemical tank area.

[0077] The tunable laser 3 is connected to the optical fiber coupler 4, and the tunable laser 3 transmits laser light of a preset wavelength to the optical fiber coupler 4. The preset wavelength is 760 nm.

[0078] Laser is emitted to the film layer 222 of each oxygen sensor through the optical fiber coupler 4. The laser and oxygen undergo photothermal absorption effect to generate heat. The dual-material beam 22 absorbs the heat energy and deforms. The deformation is amplified by the multiple dual-material beams 22 of the U-shaped detection body 2.

[0079] The membrane layer 222 sides of the plurality of oxygen sensors are connected to the optical fiber coupler 4 via optical fibers.

[0080] The optical fiber coupler 4 is connected to the signal processing mechanism 5, and the optical fiber coupler 4 transmits the signal to the signal processing mechanism 5. By detecting the displacement of the free end of the dual-material beam 22, the oxygen concentration in the pipeline is inverted.

[0081] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0082] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. An oxygen sensor, characterized in that: It includes a shell and a U-shaped detection body; The U-shaped detection body includes a double-material beam and a single-material beam; There are at least two dual-material beams, including a base beam and a film layer plated on the upper surface of the base beam, the base beam is made of a first material, the film layer is made of a second material, and the first material and the second material have different thermal expansion coefficients; The single-material beams are at least two and are made of a third material; The dual-material beams and the single-material beams are connected alternately in sequence, and at least two of the dual-material beams are arranged in parallel, and at least two of the single-material beams are arranged in parallel, and the leading end and the trailing end are both the dual-material beams, so that the single-material beams and the dual-material beams form a U-shape; An end of the double-material beam at the end facing away from the single-material beam is fixed in the housing; One end of the dual material beam is fixed to the housing as a fixed end, and the other end is a free end; The housing is provided with an inlet and an outlet to allow gas to enter and exit.

2. The oxygen sensor according to claim 1, characterized in that: The first material and / or the third material is polyimide.

3. The oxygen sensor according to claim 2, characterized in that: The second material is aluminum or silver.

4. The oxygen sensor according to claim 1, characterized in that: The base beam is a rectangular parallelepiped, and the film layer is plated on one surface of the base beam.

5. The oxygen sensor according to claim 1, characterized in that: The thickness of the film layer is 200nm, and the thickness of the base beam is 25um.

6. The oxygen sensor according to any one of claims 1 to 5, characterized in that: Each of the dual-material beams is provided with a through hole.

7. An oxygen measuring device for a petrochemical tank area, characterized in that: An oxygen sensor comprising a plurality of claims 1 to 6, further comprising a tunable laser, a fiber coupler and a signal processing mechanism; A plurality of the oxygen sensors are respectively arranged on pipelines in the petrochemical tank area; The tunable laser is connected to the optical fiber coupler; emitting laser light to the film layer of each of the oxygen sensors through the optical fiber coupler; The membrane layer sides of the plurality of oxygen sensors are connected to the optical fiber coupler via optical fibers; The optical fiber coupler is connected to the signal processing mechanism.

8. An oxygen measurement method for a petrochemical tank farm, characterized in that: The oxygen measuring device for a petrochemical tank farm according to claim 7 comprises: The plurality of oxygen sensors are respectively arranged on pipelines in the petrochemical tank area; Connecting the tunable laser to the optical fiber coupler, wherein the tunable laser transmits laser light of a preset wavelength to the optical fiber coupler; The optical fiber coupler emits laser light to the film layer of each oxygen sensor, the laser light and oxygen undergo photothermal absorption effect to generate heat, the dual-material beam absorbs the heat energy and deflects, and the deflection is amplified by the multiple dual-material beams of the U-shaped detection body; Connecting the membrane layer sides of the plurality of oxygen sensors to the optical fiber coupler via optical fibers; The optical fiber coupler is connected to the signal processing mechanism, and the optical fiber coupler transmits the signal to the signal processing mechanism, and the oxygen concentration in the pipeline is inverted by detecting the displacement of the free end of the dual-material beam.

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