Detection unit with adjustable range of absorption cell

Abstract

The utility model belongs to the technical field of detection instruments. The utility model provides a detection unit with an adjustable range of an absorption cell. The detection unit comprises a light source, a detector, the absorption cell, a to-be-detected substance inlet, a substrate substance inlet, a first discharged substance outlet, a second discharged substance outlet, a two-way valve, a three-way valve and a substrate substance pipe, a light source and a detector are arranged at two ends of the absorption cell; the to-be-detected substance inlet and the substrate substance outlet are respectively arranged at two ends of the absorption cell; the first discharged substance outlet is formed between the to-be-detected substance inlet and the substrate substance outlet; the first discharged substance outlet is provided with a two-way valve; a three-way valve is arranged at the substrate material inlet. The detection unit provided by the utility model has the advantages of simple structure, good repeatability, strong reliability, low cost, free and rapid switching of multiple optical paths and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of detection instruments, and particularly relates to the technical field of automatically adjusting the thickness of an effective absorption layer of an absorption pool so as to realize the detection of a wide concentration range of a substance to be detected. Background Art

[0002] Existing detection instruments usually use fixed-length absorption cells, that is, the thickness of the absorption layer cannot be adjusted after the equipment is manufactured. This will result in the instrument being unable to simultaneously take into account the measurement needs of the same substance to be tested under high and low concentration conditions, or the simultaneous measurement of multiple mixed substances to be tested with large absorbance differences.

[0003] In response to this problem, the prior art discloses some absorption cell solutions capable of adjusting the optical path (absorption thickness), which can be roughly divided into three categories: the first category is a device with a motion mechanism, which realizes optical path adjustment by controlling the relative position change of the cavity mirror and the cavity, such as patent CN103163641B discloses a device for realizing multi-optical path changes by rotating an angle mirror; patent CN111982817B discloses a device for realizing optical path adjustment by rotating a cavity; the second category is a device without a motion mechanism, which realizes optical path adjustment by increasing the number of light sources and detectors or adopting crystal optical technology, by multiplexing some gas cells or using electro-induced or polarization principles to change the propagation direction of the optical path, such as patent CN108732130B discloses a method for increasing the optical path by using a polarization device; the third category is to connect multiple gas cells in series, and realize optical path adjustment by manual or automatic gas path or optical path switching, such as patent CN111077083A discloses a multi-gas cell detection structure, and selects the gas cell by switching the reversing valve to realize optical path adjustment. The first type has a motion mechanism. The vibration and wear caused by the adjustment process and the slight difference in the posture of the optical element in each adjustment will lead to deviations in the optical detection results. At the same time, this type of motion mechanism has problems with service life and switching speed, which makes it difficult to meet the fast and frequent switching requirements of many industrial sites. Although the second type does not have a motion mechanism, the various optical components added are costly and complex in structure, and the debugging difficulty is relatively large; more importantly, the measurement accuracy is related to the stability of the light source intensity and the detector response. The consistency between the multi-channel light source and the detector and its consistency with the changing trend of the external environment will directly affect the performance of the instrument. Therefore, this type of solution not only adds hardware components, but also adds a lot of testing, calibration and control work. The third type of solution is simpler in structure than the first two. There is no motion mechanism and no complex optical path structure. However, the use of multiple gas pools increases the difficulty of assembly and debugging, and also doubles the number of windows on the detection path. The increase in the number of windows will greatly reduce the transmittance of the detection light, especially when the substance to be tested is polluting or corrosive, its impact on the optical path will increase exponentially. In addition, the optical path length adjustment ratio that can be achieved by this method is determined after the structure is fixed, and it cannot be flexibly adjusted in actual application. Summary of the invention

[0004] In view of this, the utility model provides a detection unit with an adjustable range of an absorption cell, comprising: a light source, a detector, an absorption cell, an inlet for a substance to be measured, an inlet for a substrate substance, a first outlet for a discharged substance, a second outlet for a discharged substance, a two-way valve, a three-way valve, and a substrate substance tube; light sources and detectors are arranged at both ends of the absorption cell; the inlet for a substance to be measured and the inlet for a substrate substance are respectively arranged at both ends of the absorption cell; the first outlet for a discharged substance is arranged between the inlet for a substance to be measured and the inlet for a substrate substance; the first outlet for a discharged substance is arranged with a two-way valve; the inlet for a substrate substance is arranged with a three-way valve, and the inlet for a substrate substance is connected to a first interface of the three-way valve; the second interface of the three-way valve is connected to the substrate substance tube; the third interface of the three-way valve is connected to the second outlet for a discharged substance.

[0005] In a specific embodiment of the present invention, the positions of the light source and the detector can be interchanged.

[0006] In a specific embodiment of the present invention, the first outlet for discharging substances is arranged at a distance from the inlet of the substance to be tested which is one tenth to nine tenths of the physical length of the absorption cell.

[0007] In a specific embodiment of the present invention, the absorption cell is an absorption cell without a return light path or an absorption cell with one or more return light paths.

[0008] In a specific embodiment of the present invention, the flow direction of the substance to be detected in the absorption cell is consistent with or opposite to the propagation direction of the detection light.

[0009] In a specific embodiment of the present invention, further, the first outlet for discharging substances is arranged at a distance from the inlet of the substance to be tested that is five tenths of the physical length of the absorption cell.

[0010] In a specific embodiment of the utility model, the detection unit with adjustable absorption cell range further includes: a control module, and the control module is respectively connected to the two-way valve, the three-way valve and the detector through lines or signals.

[0011] The utility model also provides a method for measuring the concentration of a substance to be measured by the detection unit with adjustable range of the absorption cell, comprising the following steps: determining a measurement method of a low sensitivity range or a high sensitivity range according to the concentration of the substance to be measured;

[0012] The low-sensitivity range measurement method comprises the following steps: the two-way valve is opened, and the first interface and the second interface of the three-way valve are connected; the substance to be measured enters the absorption cell from the substance to be measured inlet, and the substrate substance enters the absorption cell after passing through the second interface and the first interface of the three-way valve; the substance to be measured and the substrate substance are both discharged from the first discharge material outlet; the detector detects the light signal in the absorption cell and calculates the concentration of the substance to be measured;

[0013] The high-sensitivity range measurement method comprises the following steps: the two-way valve is closed, and the first interface and the third interface of the three-way valve are connected; the substance to be measured enters the absorption cell from the substance to be measured inlet, and is discharged from the absorption cell from the substrate material inlet after passing through the first interface, the third interface, and the second discharge material outlet of the three-way valve; the detector detects the light signal intensity signal in the absorption cell and calculates the concentration of the substance to be measured.

[0014] The detection unit provided by the utility model has the advantages of simple structure, good repeatability, high reliability, low cost, free and fast switching of multiple optical paths, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of a detection and analysis unit with an adjustable absorption cell range.

[0016] Figure 2 It is a structural diagram of a detection unit with adjustable range in a reentry absorption cell.

[0017] Figure 3 It is a structural diagram of a detection unit with adjustable range in a reentry absorption cell.

[0018] Figure 4 It is a structural diagram of a detection unit with adjustable range in a reentry absorption cell.

[0019] Among them, 1 is the light source, 2 is the detector, 3 is the absorption cell, 4 is the inlet of the substance to be tested, 5 is the inlet of the base substance, 6 is the first outlet for discharging the substance, 7 is the two-way valve, 8 is the three-way valve, 9 is the second outlet for discharging the substance, 10 is the base substance tube, and 11 is the component for changing the propagation direction of the detection light. DETAILED DESCRIPTION

[0020] Lambert-Beer law: also known as Beer's law, Beer's law, Beer-Lambert law, Bouguer-Lambert-Beer law, is the basic law of light absorption, applicable to all electromagnetic radiation and all light-absorbing substances, including gases, solids, liquids, molecules, atoms and ions. Lambert-Beer law means that the amount of light absorbed is proportional to the number of molecules that produce light absorption in the light path. The physical meaning is that when a beam of parallel monochromatic light passes vertically through a uniform non-scattering light-absorbing substance, its absorbance A is proportional to the concentration c of the light-absorbing substance and the thickness b of the absorption layer, and is inversely correlated with the transmittance T.

[0021] Substance to be tested: refers to the target substance to be tested that needs to be measured in the substance entering the detection and analysis unit. Its form includes but is not limited to gas, liquid and multi-form mixture, and its material composition includes but is not limited to single substance and mixed substance.

[0022] Base material: refers to background material that has no response within the detector measurement range or does not interfere with the detection of the substance to be measured. Its form includes but is not limited to gas, liquid and multi-form mixture, and its material composition includes but is not limited to single substance and mixed substance.

[0023] Absorption cell: refers to the part in the detection and analysis unit used to carry substances and perform detection and analysis. Both ends are usually provided with light-transmitting components such as windows and lenses to allow the detection light to pass through. In order to achieve wide-range detection, the absorption cell in this patent specifically refers to an absorption cell whose structure can satisfy that the flow path of the substance to be detected is consistent with or opposite to the propagation path of the detection light; that is, the absorption cell can be an extension of a straight-through cell or a multiple-return cell.

[0024] Optical path: In this patent, the optical path represents the propagation distance of the detection light emitted by the light source in the absorption cell. For a straight-through absorption cell, the optical path is basically equivalent to the physical length L inside the absorption cell; for a return absorption cell, if the number of returns is n, the optical path is approximately equal to (n+1)*L.

[0025] Effective optical path: It represents the distance that the detection light emitted by the light source interacts with the substance to be tested when propagating in the absorption cell. This distance is related to the effective outlet position of the discharged substance in the absorption cell.

[0026] Range: The concentration range of the substance to be tested that can be measured based on the current effective optical path. By switching different outlets for discharging substances, the effective optical path of the absorption cell can be changed, thereby achieving the range switching of the detection unit. Example

[0027] The utility model proposes a simpler detection unit with adjustable absorption cell range. The absorption cell in the detection unit has no moving parts, does not require complex optical structures, has a single light source and detector, and a single absorption cell. It is easy to assemble, simple to debug, and has low maintenance difficulty. At the same time, the absorption cell can be set with a variety of range adjustment ratios, and the ratios can be arbitrarily selected. In conjunction with the signal monitoring and valve control functions in the detection and analysis unit, it can achieve adaptive wide-range detection and analysis of the concentration of the substance to be tested.

[0028] The utility model provides an adjustable absorption cell effective absorption layer thickness, thereby realizing a detection unit for a wide concentration range of a substance to be detected. The detection cell passages are arranged at different positions of the absorption cell, and the flow direction of the substance to be detected and the proportion of the substance to be detected and the base material in the absorption cell are controlled by a valve, so as to realize the adjustment of the absorption layer thickness, thereby realizing the detection and analysis of a wide concentration range of the substance to be detected without changing the detection and analysis unit, especially the absorption cell structure.

[0029] The utility model provides a detection unit with an adjustable absorption cell range, comprising a light source, a detector, an absorption cell, an inlet for a substance to be tested, an inlet for a substrate substance, a first outlet for discharged substance, a second outlet for discharged substance, a two-way valve, a three-way valve and a substrate substance tube.

[0030] like Figure 1 and Figure 2 As shown, the optical path is the physical length of the absorption cell; the effective optical path is the length from the inlet of the substance to be tested to the inlet of the substrate substance or the outlet of the first discharged substance. The absorption cell includes an absorption cell in which the propagation direction of the detection light emitted by the light source is not changed and an absorption cell in which the propagation direction of the detection light emitted by the light source is changed; the absorption cell in which the propagation direction of the detection light emitted by the light source is changed contains a component for changing the propagation direction of the detection light, and the component for changing the propagation direction of the detection light is preferably a light reflector; the change in the propagation direction of the detection light is that the propagation direction of the detection light is inconsistent with the propagation direction of the original detection light when passing through the component for changing the propagation direction of the detection light, and it can be a change of any angle, for example, it can be a change of 90 degrees or 180 degrees.

[0031] The light source and the detector are arranged near the absorption cell, and the detector is arranged at the place where the detection light emits from the absorption cell, so as to detect the emitted detection light most efficiently; for example, for the absorption cell whose detection light direction is not changed, the light source and the detector are arranged at both ends of the aforementioned absorption cell; for the absorption cell whose detection light direction is changed, if the detection light direction changes by 180 degrees, the light source and the detector are arranged at the same end of the aforementioned absorption cell; the positions of the light source and the detector can be interchangeable.

[0032] The inlet for the substance to be tested and the inlet for the substrate substance are respectively arranged at the two ends of the absorption cell and no dead volume is left as much as possible, so as to fully utilize the length of the absorption cell and achieve the maximum effective optical path and measurement range.

[0033] The first discharge outlet is arranged between the inlet of the substance to be measured and the inlet of the substrate, so as to divide the measuring range of the absorption pool into two different measuring ranges; the first measuring range is the distance between the first discharge outlet and the inlet of the substance to be measured; the second measuring range is the distance between the inlet of the substance to be measured and the inlet of the substrate. The first discharge outlet is provided with a two-way valve to realize the conduction and closing of the pipeline.

[0034] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is one tenth of the physical length of the absorption cell.

[0035] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is two tenths of the physical length of the absorption cell.

[0036] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is three tenths of the physical length of the absorption cell.

[0037] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is four tenths of the physical length of the absorption cell.

[0038] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is five tenths of the physical length of the absorption cell.

[0039] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is six tenths of the physical length of the absorption cell.

[0040] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is seven tenths of the physical length of the absorption cell.

[0041] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is eight tenths of the physical length of the absorption cell.

[0042] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is nine-tenths of the physical length of the absorption cell.

[0043] The first outlet for discharging substances may be arranged at a distance from the inlet for the substance to be detected that is one third of the physical length of the absorption cell.

[0044] The first discharge material outlet can be set at a distance of two-thirds of the physical length of the absorption cell from the inlet of the substance to be tested. The substrate material inlet is provided with a three-way valve, the substrate material inlet is connected to the first interface of the three-way valve; the second interface of the three-way valve is connected to the substrate material tube; the third interface of the three-way valve is connected to the second discharge material outlet.

[0045] The two-way valve can be a two-way valve that can be controlled to open or close by a circuit.

[0046] The three-way valve can be a three-way valve that can be controlled to open or close by a circuit.

[0047] The detection unit with adjustable absorption cell range also includes a control module, which is connected to the two-way valve and the three-way valve through lines or signals respectively; the control module is connected to the detector through lines or signals.

[0048] The absorption cell is an absorption cell in which the flow path of the substance to be tested is consistent with or opposite to the propagation path of the detection light; it can also be an absorption cell with one or more return light paths built with optical elements with return functions such as reflectors and dove prisms.

[0049] Furthermore, by monitoring the detector signal, automatic control of valves and passages is achieved through a program, thereby realizing adaptive wide-range detection and analysis of the concentration of the substance to be measured.

[0050] The utility model provides a detection unit with adjustable absorption pool range, the structure of which is as follows: Figure 1 and 2 As shown. The detection light emitted by the light source passes through the absorption cell, interacts with the substance to be measured in the absorption cell, and then enters the detector. The detector can analyze the type and concentration of the substance to be measured by comparing the changes in the light signal when there is no substance to be measured and when there is a substance to be measured in the absorption cell. The control module analyzes the detector signal intensity in real time, and adaptively controls the two-way valve and the three-way valve according to the instrument measurement requirements, adjusts the ratio of the substance to be measured and the substrate substance in the absorption cell, and changes the maximum absorption layer thickness to achieve the switching between the first range and the second range, thereby achieving the change of the measurement concentration range.

[0051] The method for measuring the concentration of a substance to be tested comprises the following steps:

[0052] A measurement method for determining a low sensitivity range or a high sensitivity range according to the concentration of the substance to be measured;

[0053] The low-sensitivity range measurement method comprises the following steps:

[0054] The two-way valve is opened, and the first interface and the second interface of the three-way valve are connected.

[0055] The substance to be tested enters the absorption cell from the substance to be tested inlet, and the substrate enters the absorption cell after passing through the second interface and the first interface of the three-way valve;

[0056] The substance to be tested and the substrate substance are both discharged from the first discharge outlet;

[0057] The detector detects the light signal intensity signal in the absorption cell and calculates the concentration of the substance to be measured.

[0058] The high-sensitivity range measurement method comprises the following steps:

[0059] The two-way valve is closed, and the first and third interfaces of the three-way valve are connected.

[0060] The substance to be tested enters the absorption pool from the substance to be tested inlet, and is discharged from the absorption pool from the substrate inlet through the first interface, the third interface, and the second discharge outlet of the three-way valve;

[0061] The detector detects the light signal intensity signal in the absorption cell and calculates the concentration of the substance to be measured.

[0062] For example, when the concentration of the substance to be measured is low and the sensitivity of the instrument needs to be improved, the control module can be used to connect the a and b ports of valve F1, close the c port, and close valve F2 at the same time, so that the detection and analysis unit is in the first range. In this way, the substance to be measured enters the absorption cell and is discharged from the device through the b port of valve F1. The substance to be measured fills the entire absorption cell. At this time, the absorption layer thickness is the largest and the sensitivity of the device is the highest. When the concentration of the substance to be measured is high and the absorption saturation cannot be measured normally, the control module can be used to connect the a and c ports of valve F1, close the b port, and open valve F2 at the same time, so that the detection and analysis unit is in the second range. In this way, the substance to be tested enters the absorption cell and is discharged from the analysis unit through valve F2. At the same time, the substrate substance enters the absorption cell through port a of valve F1 and is also discharged from the analysis unit through valve F2. At this time, the substance to be tested and the substrate substance respectively fill the left and right halves of the absorption cell bounded by valve F2. Since the substrate substance has no effect on the substance to be tested, the thickness of the absorption layer is the left part of valve F2, so the concentration of the substance that can be measured by the analysis unit is increased, and the increase ratio is positively correlated to the ratio of the total volume of the absorption cell to the volume on the left side of valve F2.

[0063] The utility model proposes a detection unit with an adjustable absorption cell range, which can adjust the range by opening and closing valves at different positions on the absorption cell, thereby realizing wide-range measurement of the substance to be measured. At the same time, under the action of the control module, automatic adjustment of the detection range is realized, thereby fully satisfying the rapid and accurate measurement of the substance to be measured under conditions of a wide range of concentration changes.

[0064] The utility model has the following characteristics: the optical-mechanical structure of the detection unit has no moving parts, good repeatability and strong reliability; the detection unit has a simple structure, no complex or expensive optical parts, and uses the same set of light sources and detectors for different optical path measurements, which is low cost and good stability. There is no need to consider the calibration problems caused by changing the light source or detector during the range switching process; the detection unit uses a single absorption cell, and no additional windows or optical elements are added to the detection path, so the detection light flux is large and the anti-pollution ability is strong. At the same time, different ranges can be adjusted by reserving the position of the valve, and more ranges can be integrated by further increasing the number of exhaust ports and valves, and free and fast switching of multiple ranges can be achieved under the action of the control module.

[0065] The detection unit proposed in the present invention can measure the form of the substance to be tested, including but not limited to gas, liquid and multi-form mixture, and its components include but are not limited to single substance and mixed substance (which can be used for wide range measurement of single substance and simultaneous measurement of mixed substances with different absorption coefficients), and the injection mode includes but is not limited to positive pressure injection and negative pressure injection.

Claims

1. A detection unit with an adjustable absorption cell range, characterized in that it comprises: Light source, detector, absorption cell, inlet for substance to be tested, inlet for substrate substance, first outlet for discharged substance, second outlet for discharged substance, two-way valve, three-way valve, substrate substance tube; The light source is arranged near the absorption cell; The detector is arranged at the place where the detection light exits the absorption pool; The inlet for the substance to be tested and the inlet for the substrate substance are respectively arranged at two ends of the absorption cell; The first outlet for discharging substances is arranged between the inlet for the substance to be tested and the inlet for the substrate substance; the first outlet for discharging substances is provided with a two-way valve; The substrate material inlet is provided with a three-way valve, the substrate material inlet is connected to the first interface of the three-way valve; the second interface of the three-way valve is connected to the substrate material pipe; the third interface of the three-way valve is connected to the second discharge material outlet.

2. The detection unit with adjustable range of the absorption cell according to claim 1 is characterized in that: The positions of the light source and the detector can be interchanged.

3. The detection unit with adjustable range of the absorption cell according to claim 1 is characterized in that: The first outlet for discharging substances is arranged at a distance from the inlet for the substance to be detected which is one tenth to nine tenths of the physical length of the absorption cell.

4. The detection unit with adjustable range of the absorption cell according to claim 1 is characterized in that: The absorption cell is an absorption cell without a return light path or an absorption cell with one or more return light paths.

5. The detection unit with adjustable range of the absorption cell according to claim 1 is characterized in that: The flow path of the substance to be detected in the absorption cell is consistent with or opposite to the propagation path of the detection light.

6. The detection unit with adjustable range of the absorption cell according to claim 3 is characterized in that: The first outlet for discharging substances is arranged at a distance from the inlet for the substance to be detected that is five tenths of the physical length of the absorption cell.

7. The detection unit with adjustable range of the absorption cell according to claim 1 is characterized in that: Also includes: A control module is respectively connected with the two-way valve, the three-way valve and the detector through lines or signals.

8. The detection unit with adjustable range of the absorption cell according to claim 1 is characterized in that: The absorption cell includes an absorption cell whose propagation direction of the detection light is not changed and an absorption cell whose propagation direction of the detection light is changed.

9. The detection unit with adjustable range of the absorption cell according to claim 8 is characterized in that: The absorption cell whose propagation direction of the detection light is changed comprises a component for changing the propagation direction of the detection light.

Images