CN114264642A - Gas Raman signal enhancement device and method in multiple reflection and pressurization mode - Google Patents
Gas Raman signal enhancement device and method in multiple reflection and pressurization mode Download PDFInfo
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- CN114264642A CN114264642A CN202111391233.5A CN202111391233A CN114264642A CN 114264642 A CN114264642 A CN 114264642A CN 202111391233 A CN202111391233 A CN 202111391233A CN 114264642 A CN114264642 A CN 114264642A
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Abstract
The invention relates to a gas Raman signal enhancement device and method in a multiple reflection and pressurization mode, and belongs to the technical field of laser Raman gas analysis and detection. The invention realizes high-precision detection of the sample gas to be detected by adopting a mode of multiple reflection and pressurization, the Raman signal intensity can be enhanced by more than 40 times under the condition that the internal pressure of the gas chamber is 1Mpa, and the detection limit of carbon dioxide can reach 10 ppm. And can meet the standard requirements of various industries.
Description
Technical Field
The invention relates to a gas Raman signal enhancement device and method in a multiple reflection and pressurization mode, and belongs to the technical field of laser Raman gas analysis and detection.
Background
The existing laser Raman gas enhancement technology mainly comprises the following modes: firstly, increase laser power, because raman signal intensity is linear positive correlation with laser power, consequently, increase laser power can directly strengthen raman signal, but at present receive optical material, engineering application etc. various factors restriction, laser power also receives certain restriction. And secondly, the laser light is contacted with the gas for multiple times by adopting a multiple reflection mode, or the laser light is linearly superposed locally, so that the Raman scattering signal intensity is locally increased. Thirdly, a surface enhancement technology is adopted, and a special material is adopted to carry out local enrichment on the sample to be detected, so that the enhancement of the Raman scattering signal is realized. And fourthly, continuously filling the gas sample to be detected into the closed chamber in a mode of adding atmospheric pressure, increasing the internal pressure of the closed chamber, and increasing the number of the gas samples to be detected, thereby increasing the Raman scattering signal intensity of the sample to be detected.
The laser Raman gas detection technology has strong technical advantages and is a detection mode with great prospect in the field of future gas detection. However, the current laser raman gas detection technology has the problem that the intensity of raman scattering signals is too small, and the application of the technology in many industrial fields is greatly limited. Therefore, increasing the raman signal intensity of gas lasers becomes a core problem in this field of technology.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a gas Raman signal enhancement device adopting a multi-reflection and pressurization mode, which integrates the multi-reflection and pressurization modes into a whole, can greatly increase the strength of a gas laser Raman signal, can improve the strength of the gas Raman signal by more than 40 times under the condition of increasing 10 atmospheric pressures, can reach about 10ppm of detection limit of carbon dioxide, and can meet the standard requirements of various industrial fields such as petroleum logging, energy and the like. The method aims to provide a higher method for enhancing the Raman signal for the field of laser Raman gas detection, and has strong practicability.
The technical scheme of the invention is as follows:
a gas Raman signal enhancement device adopting multiple reflection and pressurization modes comprises a pressurization pump, a first electromagnetic valve, an air inlet pipeline, an air chamber, a Raman signal collection device, a control device, a first reflector, a second reflector, a pressure sensor, a second electromagnetic valve and an air outlet pipeline;
the pressurizing pump is used for pumping gas to be tested into the gas chamber through the gas inlet pipeline, and the pressure in the gas chamber is maintained at 1Mpa through the pressurizing pump;
a first electromagnetic valve is arranged on the air inlet pipeline between the pressure pump and the air chamber, and the opening and closing of the air inlet pipeline are controlled by the first electromagnetic valve;
the gas chamber is of a closed structure, the gas chamber is used for storing gas to be tested, a light-transmitting window sheet is additionally arranged on the gas chamber, multiple-reflection laser is guided into the gas chamber through the light-transmitting window sheet additionally arranged on the gas chamber, interaction between the gas to be tested and the laser is carried out, and a Raman scattering signal is generated;
the Raman signal collecting device is used for collecting a Raman scattering signal of the gas to be tested;
the first reflector is arranged on one side of the air chamber, the second reflector is arranged on the other side of the air chamber, and the first reflector and the second reflector are used for realizing multiple reflection of laser;
the gas to be tested in the gas chamber is discharged through a gas outlet pipeline, and a pressure sensor and a second electromagnetic valve are installed on the gas outlet pipeline;
the pressure sensor is used for acquiring pressure data inside the air chamber;
the second electromagnetic valve is used for controlling the opening and closing of the air outlet pipeline;
the control device is used for controlling the signal acquisition of the pressure sensor and is also used for controlling the switches of the pressure pump, the first electromagnetic valve and the second electromagnetic valve.
A gas Raman signal enhancement method in a multiple reflection and pressurization mode comprises the following steps:
firstly, adding gas to be tested into a gas chamber through a gas inlet pipeline by a booster pump;
secondly, regulating the second electromagnetic valve to be closed through a control device, collecting data of the pressure sensor through the control device, and if the data returned by the pressure sensor reaches 1Mpa, closing the first electromagnetic valve through the control device and closing the pressure pump;
thirdly, after being reflected for multiple times by the first reflecting mirror and the second reflecting mirror, the laser irradiates into the gas chamber through a light-transmitting window sheet on the gas chamber, and the laser interacts with the gas to be tested in the gas chamber to generate a Raman scattering signal;
fourthly, collecting the generated Raman scattering signals by a Raman scattering signal collecting device;
and fifthly, after the collection is finished, the control device controls the second electromagnetic valve to be opened to discharge the gas.
And sixthly, if the work is not stopped, returning to the first step.
Advantageous effects
The invention realizes high-precision detection of the sample gas to be detected by adopting a mode of multiple reflection and pressurization, the Raman signal intensity can be enhanced by more than 40 times under the condition that the internal pressure of the gas chamber is 1Mpa, and the detection limit of carbon dioxide can reach 10 ppm. And can meet the standard requirements of various industries.
Drawings
FIG. 1 is a schematic diagram of a multiple reflection and pressurized gas Raman structure of the present invention;
FIG. 2 is a schematic flow diagram of the process of the present invention;
FIG. 3 is a Raman spectrum of the test under 10 atmospheric conditions at 10ppm concentration of 6 sample gases (hydrogen, carbon dioxide, oxygen, carbon monoxide, nitrogen, hydrogen sulfide) to be tested;
FIG. 4 is a schematic three-dimensional structure of the air chamber.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
As shown in fig. 1, a gas raman signal enhancement device adopting a multiple reflection and pressurization mode includes a pressurization pump 1, a first electromagnetic valve 2, an air inlet pipeline 3, an air chamber 4, a raman signal collecting device 5, a control device 6, a first reflector 7, a second reflector 8, a pressure sensor 9, a second electromagnetic valve 10, and an air outlet pipeline 11;
the pressurizing pump 1 is used for pumping gas to be tested into the gas chamber 4 through the gas inlet pipeline 3, and the pressure in the gas chamber 4 is maintained at 1Mpa through the pressurizing pump 1;
a first electromagnetic valve 2 is arranged on an air inlet pipeline 3 between the pressure pump 1 and the air chamber 4, and the opening and closing of the air inlet pipeline 3 are controlled by the first electromagnetic valve 2;
as shown in fig. 4, the gas chamber 4 is of a closed structure, the gas chamber 4 is used for storing gas to be tested, a light-transmitting window sheet is additionally arranged on the gas chamber 4, multiple-reflection laser is guided into the gas chamber 4 through the light-transmitting window sheet additionally arranged on the gas chamber 4, interaction between the gas to be tested and the laser is performed, and a raman scattering signal is generated;
the Raman signal collecting device 5 is used for collecting Raman scattering signals of the gas to be tested;
the first reflector 7 is arranged on one side of the gas chamber 4, the second reflector 8 is arranged on the other side of the gas chamber 4, and the first reflector 7 and the second reflector 8 are used for realizing multiple reflection of laser;
the gas to be tested in the gas chamber 4 is discharged through a gas outlet pipeline 11, and a pressure sensor 9 and a second electromagnetic valve 10 are installed on the gas outlet pipeline 11;
the pressure sensor 9 is used for acquiring pressure data inside the air chamber 4;
the second electromagnetic valve 10 is used for controlling the opening and closing of the gas outlet pipeline 11;
the control device 6 is used for controlling the signal acquisition of the pressure sensor 9 and controlling the on-off of the pressure pump 1, the first electromagnetic valve 2 and the second electromagnetic valve 10.
As shown in fig. 2, a method for enhancing a raman signal of a gas by multiple reflection and pressurization, the method comprises the steps of:
firstly, adding gas to be tested into a gas chamber 4 through an air inlet pipeline 3 by a booster pump 1;
secondly, regulating the second electromagnetic valve 10 to be closed through the control device 6, collecting data of the pressure sensor 9 through the control device 6, if the data returned by the pressure sensor 9 reaches 1Mpa, closing the first electromagnetic valve 2 through the control device 6, and closing the pressure pump 1;
thirdly, after being reflected for multiple times by the first reflecting mirror 7 and the second reflecting mirror 8, the laser irradiates into the gas chamber 4 through a light-transmitting window sheet on the gas chamber 4, and the laser interacts with the gas to be tested in the gas chamber 4 to generate a Raman scattering signal;
fourthly, collecting the generated Raman scattering signals by a Raman scattering signal collecting device 5;
and fifthly, after the collection is finished, the control device 6 controls the second electromagnetic valve 10 to be opened to discharge the gas.
And sixthly, if the work is not stopped, returning to the first step.
Examples
A gas Raman signal enhancement method in a multiple reflection and pressurization mode comprises the following steps:
the laser light is first introduced into the first mirror 7 and the second mirror 8 to achieve multiple reflections. The control device controls the second electromagnetic valve 10 to be closed, the air outlet pipeline 11 of the air chamber is closed, the first electromagnetic valve 2 is controlled to be opened, the pressure pump 1 is started, and the sample air is pressed into the air chamber 4. The control device 6 collects signals of the pressure sensor, and after the signals reach a set pressure value, the first electromagnetic valve 2 is closed, and the pressure pump is closed, so that the internal pressure of the air chamber reaches a set value. And starting the Raman signal collecting device to collect Raman signals of the sample gas, and after the signal collection is finished, controlling the second electromagnetic valve 10 to be opened by the control device to discharge the sample gas in the gas chamber 4. If the work is not stopped, the cycle is repeated, the Raman spectrogram of the gas to be tested is shown in figure 3, the concentration of 6 sample gases (hydrogen, carbon dioxide, oxygen, carbon monoxide, nitrogen and hydrogen sulfide) to be tested in figure 3 is 10ppm, and the Raman spectrogram is tested under the condition of 10 atmospheric pressures;
the first reflector 7 and the second reflector 8 are both concave reflectors, with a 1 inch (25.4mm) diameter lens and a 25mm focal length. The first mirror 7 and the second mirror 8 are spaced apart by 100 mm. The reflection can be realized for more than 30 times, and the amplification can be realized for more than 30 times.
The three-dimensional structure of the air cell is shown in fig. 4. Round holes with the diameter of 18mm are arranged on the front, the back, the left and the right of the air chamber, and glass window sheets with the diameter of 25.4mm are arranged. The glass window sheet adopts a double-sided coating process, and the transmittance of laser and Raman scattering signals is increased.
The control device is realized by a circuit board. And a STM32 singlechip is adopted on the circuit board to realize logic control. The data communication with the pressure sensor is realized by adopting a serial port, and the control of the electromagnetic valve and the booster pump is realized by adopting an IO port.
Claims (10)
1. A gas Raman signal enhancement device adopting multiple reflection and pressurization modes is characterized in that: the gas Raman signal enhancement device comprises a pressure pump (1), a first electromagnetic valve (2), an air inlet pipeline (3), an air chamber (4), a Raman signal collection device (5), a first reflector (7), a second reflector (8), a pressure sensor (9), a second electromagnetic valve (10) and an air outlet pipeline (11);
the pressurizing pump (1) is used for pumping gas to be tested into the air chamber (4) through the air inlet pipeline (3);
a first electromagnetic valve (2) is arranged on the air inlet pipeline (3) between the pressure pump (1) and the air chamber (4), and the opening and closing of the air inlet pipeline (3) are controlled through the first electromagnetic valve (2);
the gas chamber (4) is of a closed structure, gas to be tested is stored in the gas chamber (4), a light-transmitting window sheet is additionally arranged on the gas chamber (4), and multiple-reflection laser is guided into the gas chamber (4) through the light-transmitting window sheet additionally arranged on the gas chamber (4);
the Raman signal collecting device (5) is used for collecting the Raman scattering signals of the gas to be tested;
the first reflector (7) is arranged on one side of the air chamber (4), and the second reflector (8) is arranged on the other side of the air chamber (4);
the gas to be tested in the gas chamber (4) is discharged through a gas outlet pipeline (11), and a pressure sensor (9) and a second electromagnetic valve (10) are installed on the gas outlet pipeline (11);
the pressure sensor (9) is used for acquiring pressure data inside the air chamber (4);
the second electromagnetic valve (10) is used for controlling the opening and closing of the air outlet pipeline (11).
2. The multiple reflection and pressurization gas raman signal enhancement device according to claim 1, wherein:
the enhancement device also comprises a control device, wherein the control device is used for controlling the signal acquisition of the pressure sensor (9) and controlling the on-off of the pressure pump (1), the first electromagnetic valve (2) and the second electromagnetic valve (10).
3. A multiple reflection and pressurization type gas raman signal enhancement device according to claim 1 or 2, characterized in that:
the pressure in the gas chamber (4) was maintained at 1MPa by the pressurizing pump (1).
4. A multiple reflection and pressurization type gas raman signal enhancement device according to claim 1 or 2, characterized in that:
and light-transmitting window sheets are additionally arranged on four side surfaces of the air chamber (4).
5. The multiple reflection and pressurization gas Raman signal enhancement device of claim 4, wherein:
the first reflector (7) and the second reflector (8) are used for realizing multiple reflection of the laser.
6. The multiple reflection and pressurization gas Raman signal enhancement device of claim 4, wherein:
the diameter of the light-transmitting window sheets arranged on the four side surfaces of the air chamber (4) is 25.4mm, and the glass window sheets adopt a double-sided coating process.
7. The multiple reflection and pressurization gas Raman signal enhancement device of claim 2, 5 or 6, wherein:
the control device is realized by a circuit board, and the circuit board is logically controlled by an STM32 singlechip.
8. The multiple reflection and pressurization gas raman signal enhancement device according to claim 7, wherein:
the control device adopts a serial port to realize data communication with the pressure sensor, and adopts an IO port to realize control of the electromagnetic valve and the booster pump.
9. A gas Raman signal enhancement method in a multiple reflection and pressurization mode is characterized by comprising the following steps:
firstly, adding gas to be tested into a gas chamber (4) through an air inlet pipeline (3) by a booster pump (1);
secondly, regulating the second electromagnetic valve (10) to be closed through a control device, acquiring data of the pressure sensor (9) through the control device, and closing the first electromagnetic valve (2) and closing the pressure pump (1) through the control device 6 if the data returned by the pressure sensor (9) is not less than 1 Mpa;
thirdly, after being reflected for multiple times by the first reflector (7) and the second reflector (8), the laser irradiates the air chamber (4) through a light-transmitting window sheet on the air chamber (4), and interacts with the gas to be tested in the air chamber (4) to generate a Raman scattering signal;
fourthly, collecting the generated Raman scattering signals through a Raman scattering signal collecting device (5);
and fifthly, after the collection is finished, the control device controls the second electromagnetic valve (10) to be opened to discharge the gas, and the Raman signal enhancement of the gas to be tested is finished.
10. The method of claim 9, wherein the raman signal enhancement method comprises a multiple reflection and pressurization method, and further comprises:
and if the Raman signal enhancement is continuously carried out on the gas to be tested, returning to the first step.
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