Laser gas detection device and gas concentration detection method thereof

Abstract

The invention discloses a laser gas detection device and a gas concentration detection method thereof.A detection unit is used for analyzing spectral characteristics of an electric signal sent by a light receiving unit, the original gas concentration is calculated according to the spectral characteristics, and the change amplitude of the light intensity of a laser beam under ambient light interference is judged according to a preset light intensity value; the original gas concentration is compensated according to the change amplitude of the light intensity of the laser beam to obtain the final gas concentration, so that the influence of ambient light on the gas concentration detection precision is overcome, the gas concentration detection precision is improved, and the gas detection alarm accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas concentration detection, and in particular to a laser gas detection device and a gas concentration detection method thereof. Background Art

[0002] At present, the commonly used gas detection method is to detect gas concentration with the help of tunable diode laser absorption spectroscopy (TDLAS). Linear laser gas detector is a gas remote sensing device with a fixed optical path, usually used to detect gas leaks in fixed gas transportation pipelines, including the opposite type and the reflection type. The opposite type means that the light emitting unit and the light receiving unit are fixedly installed at both ends of the optical path, and the reflection type means that the light emitting unit and the light receiving unit are fixedly installed on the same side of the optical path, and a reflective device, such as a high reflectivity reflector, is installed at the other end of the optical path.

[0003] Existing linear laser combustible gas detectors have poor resistance to light interference and are prone to false alarms or missed alarms under the interference of ambient light such as outdoor sunlight and indoor halogen tungsten lamps, thus affecting the gas detection alarm rate. Summary of the invention

[0004] In view of this, the present invention provides a laser gas detection device and a gas concentration detection method thereof, so as to solve the problem that the existing linear laser combustible gas detector has poor anti-light interference ability and is prone to false alarm or missed alarm under ambient light interference.

[0005] A laser gas detection device comprises a light emitting unit, a light receiving unit, a detection unit, a main control unit, a display unit and a power supply unit.

[0006] The light emitting unit is used to emit a laser beam according to the control instruction of the main control unit, and the laser beam enters the light receiving unit after passing through the air mass to be measured;

[0007] The light receiving unit is used to convert the received light signal into an electrical signal and transmit it to the detection unit;

[0008] The detection unit is used to analyze the spectral characteristics of the acquired signal, calculate the original concentration of the gas according to the spectral characteristics, and determine the change amplitude of the laser beam intensity under the interference of ambient light according to the preset light intensity value, and compensate the original concentration of the gas according to the change amplitude of the laser beam intensity to obtain the final gas concentration;

[0009] The main control unit is used to issue a display instruction according to the final gas concentration calculated by the detection unit, so as to display the gas concentration on the display unit;

[0010] The power supply unit is used to supply power to the detection unit and the main control unit.

[0011] Preferably, a reflecting unit is further included, and the reflecting unit is used to reflect the laser light beam passing through the air mass to be measured to the light receiving unit.

[0012] Preferably, an alarm module is also included, the power supply end of the alarm module is connected to the power supply unit, and the alarm module is used to issue an alarm prompt when the gas concentration exceeds a set threshold.

[0013] Preferably, it also includes a memory, which is connected to the main control unit and is used to store data received by the storage unit and its sending instruction program.

[0014] Preferably, the calculation formula for the final gas concentration is:

[0015] C = C0*k;

[0016] k=a*△S+b or k=a*△S 2 +b*△S+c;

[0017] Wherein, C0 is the original concentration of the gas calculated by the detection unit, k is the compensation coefficient, △S is the variation amplitude of the laser beam intensity, and a, b, and c are the factory set values ​​under different lighting conditions.

[0018] Preferably, when the variation amplitude of the laser beam intensity is 100<△S≤300, 1<k≤1.1;

[0019] When the laser beam intensity variation amplitude is 300<△S≤500, 1.1<k≤1.2;

[0020] When the variation amplitude of the laser beam intensity is 500<△S≤700, 1.2<k≤1.3.

[0021] Preferably, the laser gas detection device is a directed-type linear laser gas detector or a reflective linear laser gas detector.

[0022] A method for detecting gas concentration using the laser gas detection device specifically comprises the following steps:

[0023] S1, the main control unit controls the light emitting unit to emit a laser beam, and the laser beam passes through the air mass to be measured and directly enters the light receiving unit or enters the light receiving unit after being reflected by the reflection unit;

[0024] S2, the light receiving unit converts the received light signal into an electrical signal, and transmits the electrical signal to the detection unit;

[0025] S3, the detection unit obtains spectral characteristics according to the received electrical signal analysis, calculates the original concentration of the gas according to the spectral characteristics, and determines the change amplitude of the laser beam intensity under the interference of ambient light according to the preset light intensity value, and compensates the original concentration of the gas according to the change amplitude of the laser beam intensity to obtain the final gas concentration;

[0026] S4, the main control unit controls the display unit to display the final gas concentration.

[0027] The beneficial effects of the present invention are:

[0028] The present invention utilizes a detection unit to analyze the spectral characteristics of the electrical signal sent by the light receiving unit, calculates the original concentration of the gas according to the spectral characteristics, and determines the variation amplitude of the laser beam intensity under the interference of ambient light according to a preset light intensity value, and compensates the original concentration of the gas according to the variation amplitude of the laser beam intensity to obtain the final gas concentration, thereby overcoming the influence of ambient light on the gas concentration detection accuracy, improving the gas concentration detection accuracy, and improving the accuracy of gas detection alarm. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a schematic diagram of an opposed-beam linear laser gas detector.

[0031] Figure 2 It is a schematic diagram of a reflective linear laser gas detector.

[0032] Figure 3 It is the concentration calculation flow chart.

[0033] The meanings of the numbers in the figure are:

[0034] 1 is the main control unit, 2 is the light emitting unit, 3 is the light receiving unit, 4 is the reflecting unit, and 5 is the detecting unit. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0036] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0037] In the following description, use of suffixes such as 'module', 'part' or 'unit' used to refer to elements is merely for facilitating description of the present invention, but has no specific meaning by itself.

[0038] In order to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings.

[0039] The present invention provides a laser gas detection device, comprising a light emitting unit 2, a light receiving unit 3, a detection unit 5, a main control unit 1, a display unit and a power supply unit;

[0040] The light emitting unit 2 is used to emit a laser beam according to the control instruction of the main control unit 1, and the laser beam passes through the air mass to be measured and then enters the light receiving unit 3;

[0041] The light receiving unit 3 is used to convert the received light signal into an electrical signal and transmit it to the detection unit;

[0042] The detection unit 5 is used to analyze the spectral characteristics of the acquired signal, calculate the original concentration of the gas according to the spectral characteristics, and determine the change amplitude of the laser beam intensity under the interference of ambient light according to the preset light intensity value, and compensate the original concentration of the gas according to the change amplitude of the laser beam intensity to obtain the final gas concentration;

[0043] The main control unit 1 is used to issue a display instruction according to the final gas concentration calculated by the detection unit, so as to display the gas concentration on the display unit;

[0044] The power supply unit is used to supply power to the detection unit and the main control unit.

[0045] like Figure 1As shown in the figure, the laser gas detection device includes a light emitting unit 2, a light receiving unit 3, a detection unit 5, a main control unit 1, a display unit and a power supply unit. The main control unit 1 controls the light emitting unit 2 to emit a laser beam. The laser beam directly enters the light receiving unit 3 after passing through the air mass to be detected. The light receiving unit 3 converts the received optical signal into an electrical signal, and transmits the electrical signal to the detection unit 5. The detection unit 5 obtains spectral characteristics (such as light intensity value, correlation coefficient of signal waveform, etc.) according to the analysis of the received electrical signal, calculates the original concentration of the gas according to the spectral characteristics, and judges the variation amplitude of the laser beam intensity under the interference of ambient light according to the preset light intensity value. The original concentration of the gas is compensated according to the variation amplitude of the laser beam intensity to obtain the final gas concentration. The main control unit controls the display unit to display the final gas concentration.

[0046] like Figure 2 As shown, the laser gas detection device in the figure includes a light emitting unit 2, a light receiving unit 3, a detection unit 5, a main control unit 1, a display unit and a power supply unit, and also includes a reflection unit 4. The main control unit 1 controls the light emitting unit 2 to emit a laser beam. After the laser beam passes through the air mass to be detected, it enters the light receiving unit 3 after being reflected by the reflection unit 4. The light receiving unit 3 converts the received optical signal into an electrical signal and transmits the electrical signal to the detection unit 5. The detection unit 5 obtains the spectral characteristics (such as the light intensity value, the correlation coefficient of the signal waveform, etc.) according to the received electrical signal analysis, calculates the original concentration of the gas according to the spectral characteristics, and judges the change amplitude of the laser beam intensity under the interference of ambient light according to the preset light intensity value. The original concentration of the gas is compensated according to the change amplitude of the laser beam intensity to obtain the final gas concentration. The main control unit controls the display unit to display the final gas concentration.

[0047] Preferably, the laser gas detection device further comprises an alarm module, the power supply end of the alarm module is connected to the power supply unit, and the alarm module is used to issue an alarm prompt when the gas concentration exceeds a set threshold.

[0048] Preferably, the laser gas detection device further comprises a memory, which is connected to the main control unit and is used to store data received by the storage unit and its sending instruction program.

[0049] The present invention also provides a method for detecting gas concentration using the laser gas detection device described above, which specifically includes the following steps:

[0050] S1, the main control unit 1 controls the light emitting unit 2 to emit a laser beam, and the laser beam passes through the air mass to be measured and directly enters the light receiving unit 3 or enters the light receiving unit 3 after being reflected by the reflecting unit 4.

[0051] S2, the light receiving unit 3 converts the received light signal into an electrical signal, and transmits the electrical signal to the detection unit.

[0052] S3, the detection unit 5 obtains spectral characteristics (such as light intensity value, correlation coefficient of signal waveform, etc.) according to the received electrical signal analysis.

[0053] Since the laser gas detection device of the present application has pre-stored the initial light intensity value S0 in the detection unit 5 during the installation and debugging stage, during the gas detection process, since the optical path is fixed, if there is no external interference, the signal light intensity received by the light receiving unit 3 always fluctuates randomly within a small range, and its light intensity value can be regarded as unchanged, and only the signal waveform changes. Therefore, the original gas concentration C0 can be analyzed according to the change of the signal waveform; if the light intensity change amplitude exceeds the normal range △S0, it is regarded that the laser gas detection device is interfered by the external ambient light. At this time, the concentration detected by it will deviate due to the interference of the ambient light. Therefore, the change amplitude △S of the laser beam light intensity can be used to compensate for the original gas concentration to obtain the final gas concentration;

[0054] Usually, since the ambient interference light enters the light receiving unit 3, this part of light usually does not completely pass through the optical path containing the gas mass to be measured, and therefore does not completely contain the gas concentration information, resulting in a low analyzed concentration. Therefore, it is necessary to compensate for the analyzed concentration, and the compensation coefficient is k;

[0055] The final gas concentration is calculated as:

[0056] C = C0*k;

[0057] k=a*△S+b or k=a*△S 2 +b*△S+c;

[0058] Wherein, C0 is the original concentration of the gas calculated by the detection unit, k is the compensation coefficient, △S is the variation amplitude of the laser beam intensity, and a, b, and c are the factory set values ​​under different lighting conditions.

[0059] Preferably, in actual measurement, the compensation coefficient k and the threshold range of △S can be adjusted according to the factory calibration. When the variation range of the laser beam intensity is 100<△S≤300, 1<k≤1.1;

[0060] When the laser beam intensity variation amplitude is 300<△S≤500, 1.1<k≤1.2;

[0061] When the variation amplitude of the laser beam intensity is 500<△S≤700, 1.2<k≤1.3.

[0062] Specifically, the corresponding relationship table between the value of the compensation coefficient k and the threshold range segment of ΔS is as follows:

[0063] 100<△S<＝200 200<△S<＝300 300<△S<＝400 400<△S<＝500 500<△S<＝600 600<△S<＝700 k＝1.05 k＝1.1 k＝1.15 k＝1.2 k＝1.25 k＝1.3

[0064] S4, the main control unit 1 controls the display unit to display the final gas concentration.

[0065] The above technical solution of the present application is not only applicable to the opposite-type linear laser gas detector, but also applicable to the reflective linear laser gas detector.

[0066] It should be clear that the described embodiments are only part of the embodiments of the present invention, rather than all 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.

Claims

1. A laser gas detection device, characterized in that: It includes a light emitting unit, a light receiving unit, a detection unit, a main control unit, a display unit and a power supply unit. The light emitting unit is used to emit a laser beam according to the control instruction of the main control unit, and the laser beam enters the light receiving unit after passing through the air mass to be measured; The light receiving unit is used to convert the received light signal into an electrical signal and transmit it to the detection unit; The detection unit is used to analyze the spectral characteristics of the acquired signal, calculate the original concentration of the gas according to the spectral characteristics, and determine the change amplitude of the laser beam intensity under the interference of ambient light according to the preset light intensity value, and compensate the original concentration of the gas according to the change amplitude of the laser beam intensity to obtain the final gas concentration; The main control unit is used to issue a display instruction according to the final gas concentration calculated by the detection unit, so as to display the gas concentration on the display unit; The power supply unit is used to supply power to the detection unit and the main control unit.

2. The laser gas detection device according to claim 1, characterized in that: The device also comprises a reflection unit, which is used to reflect the laser light beam passing through the air mass to be measured to the light receiving unit.

3. The laser gas detection device according to claim 1, characterized in that: It also includes an alarm module, the power supply end of the alarm module is connected to the power supply unit, and the alarm module is used to issue an alarm prompt when the gas concentration exceeds a set threshold.

4. The laser gas detection device according to claim 1, characterized in that: It also includes a memory, which is connected to the main control unit and is used to store data received by the storage unit and its sending instruction program.

5. The laser gas detection device according to claim 1, characterized in that: The final gas concentration is calculated as: C = C0*k; k = a * △S + b or k = a * △S 2 + b * △S + c; Wherein, C0 is the original concentration of the gas calculated by the detection unit, k is the compensation coefficient, △S is the variation amplitude of the laser beam intensity, and a, b, and c are the factory set values ​​under different lighting conditions.

6. The laser gas detection device according to claim 5, characterized in that: When the laser beam intensity variation amplitude is 100<△S≤300, 1<k≤1.1; When the laser beam intensity variation amplitude is 300<△S≤500, 1.1<k≤1.2; When the variation amplitude of the laser beam intensity is 500<△S≤700, 1.2<k≤1.

3.

7. The laser gas detection device according to claim 1, characterized in that: The laser gas detection device is a directed-type linear laser gas detector or a reflective linear laser gas detector.

8. A method for detecting gas concentration using the laser gas detection device according to any one of claims 1 to 7, characterized in that: The specific steps include: S1, the main control unit controls the light emitting unit to emit a laser beam, and the laser beam passes through the air mass to be measured and directly enters the light receiving unit or enters the light receiving unit after being reflected by the reflection unit; S2, the light receiving unit converts the received light signal into an electrical signal, and transmits the electrical signal to the detection unit; S3, the detection unit obtains spectral characteristics according to the received electrical signal analysis, calculates the original concentration of the gas according to the spectral characteristics, and determines the change amplitude of the laser beam intensity under the interference of ambient light according to the preset light intensity value, and compensates the original concentration of the gas according to the change amplitude of the laser beam intensity to obtain the final gas concentration; S4, the main control unit controls the display unit to display the final gas concentration.

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