Multi-component gas concentration monitoring system and method

Abstract

The invention provides a multi-component gas concentration monitoring system and method. The system comprises a laser light source module, a light pulse module, a gas chamber type passive sensor, a photoelectric conversion module and an industrial personal computer module, the light pulse module pulses the laser output by the laser light source module and then transmits the laser to the air chamber type passive sensor; the air chamber type passive sensor comprises an air chamber, a first collimator, a second collimator and a reflecting mirror, and the reflecting mirror is used for reflecting emergent light which is emitted into the air chamber from the incident port and then emitted out from the emergent port to the incident port to be emitted out. The first collimator is used for converting divergent light beams entering the gas chamber from the entrance port into parallel light beams and emitting the parallel light beams from the exit port, and the second collimator is used for converting divergent light beams entering the gas chamber from the exit port into parallel light beams and emitting the parallel light beams from the entrance port. According to the invention, the concentration of the to-be-detected gas in the multi-component gas can be monitored, and the purpose of safety monitoring of the storage tank is achieved.

Description

Technical Field

[0001] This invention relates to the field of gas concentration monitoring technology, and specifically to a multi-component gas concentration monitoring system and method. Background Technology

[0002] During oil extraction, transportation, and refining, large quantities of flammable and harmful gases are present, mainly including methane, ethane, propane, butane, and hydrogen sulfide. Monitoring the concentration of these oil and gas components is of great significance, as concentrations exceeding certain ranges may lead to the formation of flammable and explosive gas mixtures. Therefore, it is necessary to monitor the concentration of multiple gas components in oil tanks.

[0003] Current methods for monitoring oil and gas concentrations mainly include: stationary gas monitors, infrared spectroscopy, photoelectrochemical sensors, etc. These methods have problems such as active sensors, low monitoring accuracy, and high unit cost. Summary of the Invention

[0004] To address the problems in the prior art, embodiments of the present invention provide a multi-component gas concentration monitoring system and method. The present invention can achieve long-term, real-time and continuous multi-component gas concentration monitoring to ensure production and transportation safety.

[0005] In one embodiment, the present invention provides a multi-component gas concentration monitoring system, the system comprising: a laser source module, a light pulse module, a gas chamber passive sensor, a photoelectric conversion module, and an industrial control computer module;

[0006] The optical pulse module pulses the laser output from the laser source module and transmits it to the gas chamber passive sensor. The gas chamber passive sensor includes a gas chamber, a first collimator, a second collimator, and a reflector. The gas chamber is a cavity including an inlet and an outlet. The gas chamber is used to hold the multi-component gas to be monitored. The reflector is used to reflect the outgoing light that enters the gas chamber from the inlet and exits from the outlet back to the inlet and exits. The first collimator is installed at the inlet of the gas chamber, and the second collimator is installed at the outlet of the gas chamber. The first collimator is used to convert the divergent beam entering the gas chamber from the inlet into a parallel beam that exits from the outlet. The second collimator is used to convert the divergent beam entering the gas chamber from the outlet into a parallel beam that exits from the inlet.

[0007] When the pulsed laser light enters the gas chamber through the first collimator at the entrance and is absorbed by the multi-component gas to be monitored, it exits through the second collimator at the exit. After being reflected by the mirror, it enters the gas chamber through the second collimator at the exit and then exits through the first collimator at the entrance. The photoelectric conversion module detects the light signal emitted from the first collimator at the entrance and performs photoelectric conversion before transmitting the peak light intensity of the pulsed laser signal after absorption by the multi-component gas to the industrial control computer module. The industrial control computer module calculates the concentration of the gas to be measured in the multi-component gas to be monitored based on the peak light intensity of the pulsed laser signal.

[0008] In one embodiment, the calculation of the concentration of the gas to be measured in the multi-component gas to be monitored includes:

[0009] The absorption coefficient of the gas to be tested to pulsed laser is pre-calibrated using a multi-component gas concentration monitoring system.

[0010] The concentration of the gas to be measured in the multi-component gas to be monitored is calculated based on the absorption coefficient and the peak intensity of the pulsed laser signal.

[0011] In one embodiment, when the laser source module uses lasers of multiple wavelengths, the system further includes a first coupler, which is used to couple different wavelengths of laser light after being pulsed by the optical pulse module and transmit them to the gas chamber.

[0012] In one embodiment, the system further includes a second coupler that, when the second coupler receives incident light from the first coupler, transmits the incident light to the gas chamber; and when the second coupler receives reflected light from the gas chamber, transmits the reflected light to the photoelectric conversion module.

[0013] In one embodiment, when there are N air chambers, the system further includes a third coupler that divides the incident light from the second coupler into N equal parts and transmits them to each air chamber, where N is a positive integer greater than 1.

[0014] In one embodiment, the system further includes a time-delay fiber connected to the output of each laser to distinguish different wavelengths of laser light in time.

[0015] In one embodiment, the air-cell passive sensor transmits optical signals to the laser light source module and the photoelectric conversion module using a single-core optical fiber.

[0016] In one embodiment, the system further includes a display screen connected to the industrial control computer module for displaying the concentration of the multi-component gas to be monitored.

[0017] In one embodiment, the system further includes a speaker connected to the industrial control computer module, which is used to issue an alarm when the concentration of the multi-component gas to be monitored exceeds a set threshold.

[0018] In one embodiment, the present invention also provides a method for monitoring the concentration of a multi-component gas, the method being implemented based on the multi-component gas concentration monitoring system described in any one of the preceding embodiments, comprising:

[0019] The peak intensity of the pulsed laser signal after absorption by the multi-component gas to be monitored is collected;

[0020] The concentration of the gas to be measured in the multi-component gas to be monitored is calculated based on the peak intensity of the pulsed laser signal.

[0021] This invention provides a multi-component gas concentration monitoring system and method. By developing a fiber optic gas chamber passive sensor and a matching monitoring system, this invention monitors the concentration of multiple components of gas, achieving the goal of safety monitoring of storage tanks. This invention addresses the pain points of storage tank safety monitoring and can be effectively integrated with existing monitoring results for tank deformation, earthquakes, and settlement, enhancing the monitoring capabilities of existing systems. It has promising application prospects for subsequent multi-dimensional monitoring of storage tank safety, improving the level of storage tank safety monitoring, and reducing the probability of tank farm accidents. This invention significantly reduces the operational risks of external floating roof tanks and simplifies the process of monitoring oil and gas concentrations within the sealed area of ​​the storage tank. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0023] Figure 1 This is a schematic diagram of the structure of a multi-component gas concentration monitoring system provided by the present invention;

[0024] Figure 2 This is a schematic diagram of another multi-component gas concentration monitoring system provided by the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of a gas chamber type passive sensor provided by the present invention;

[0026] Figure 4 This is a schematic diagram of the structure of another multi-component gas concentration monitoring system provided by the present invention;

[0027] Figure 5This is a flowchart of the laser signal transmission process of a multi-component gas concentration monitoring system provided by the present invention;

[0028] Figure 6 This is a flowchart of a multi-component gas concentration monitoring method provided by the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0030] In recent years, numerous oil tank fires caused by lightning strikes have occurred, resulting in significant socio-economic losses. While lightning strikes are often considered the direct cause of fires, the accumulation of oil and gas concentrations within the sealed space of storage tanks to the explosive limit is also a significant hazard. Given that the concentration of oil and gas in completely sealed tanks gradually increases, during thunderstorms, the lightning current can easily pass through conductive plates, generating sparks that ignite the oil and gas, leading to an explosion and fire. Therefore, in addition to strengthening the lightning protection design of storage tanks, reducing the concentration of oil and gas is equally important for fire prevention.

[0031] Large crude oil storage tanks are crucial equipment for crude oil reserves. Due to their large storage capacity, their failure can have severe consequences. The safe operation of these tanks plays a vital role in the long-term safe operation of the entire petroleum and petrochemical industry. During oil extraction, transportation, and refining, large quantities of flammable and hazardous gases are present, primarily including methane, ethane, propane, butane, and hydrogen sulfide. Monitoring the concentration of these gases is of paramount importance. If the concentration exceeds a certain range, it may form a flammable and explosive mixture. Accurate monitoring of the concentration of each component is significant for ensuring personnel safety, economic efficiency, and environmental protection. Timely monitoring of gas concentrations can prevent explosions that could result in casualties and property damage, effectively reduce environmental pollution, and help operators adjust operating parameters in a timely manner, thereby improving operational efficiency.

[0032] like Figure 1 The diagram shown is a structural schematic of a multi-component gas concentration monitoring system provided by an embodiment of the present invention. The multi-component gas concentration monitoring system 001 provided by the present invention includes: a laser source module 1, a light pulse module 2, a gas chamber type passive sensor 3, a photoelectric conversion module 4, and an industrial control computer module 5. Specifically, as shown... Figure 2The diagram shows a structural schematic of another multi-component gas concentration monitoring system provided by the present invention. The multi-component gas concentration monitoring system 002 provided in this embodiment mainly includes a data acquisition module 6 and a data processing module 7. The data acquisition module 6 includes a laser source module 1, a light pulse module 2, and a gas chamber type passive sensor 3. The data processing module 7 includes a photoelectric conversion module 4 and an industrial control computer module 5. The photoelectric conversion module is a photodetector used to convert the light signal reflected back from the gas chamber type passive sensor into an electrical signal, realizing subsequent signal processing, analysis, display, and alarm functions. The industrial control computer module is connected to the laser source module, light pulse module, and photoelectric conversion module through serial ports, network ports, and other interfaces to set the parameters of each module. Simultaneously, it performs signal processing and analysis on the electrical signal converted by the photoelectric conversion module to calculate the concentration value from the light intensity peak.

[0033] The optical pulse module 2 pulses the laser output from the laser source module 1 and transmits it to the gas-cell passive sensor 3. Specifically, the optical pulse module is used to pulse the continuous light output from the laser source module. Pulsed light is a special type of light wave that is brief and discrete in time. This invention can modulate the continuous light wave output from the laser source module using the modulator of the optical pulse module, causing it to change in intensity within a certain time, thereby forming pulsed light. Furthermore, this invention can also use a laser capable of generating pulsed light; by adjusting the laser parameters, pulsed light of different frequencies and widths can also be generated. This invention can effectively collect the peak pulse intensity of different gases using pulsed light.

[0034] like Figure 3The diagram shows a structural schematic of a gas chamber type passive sensor 3 provided by the present invention. The gas chamber type passive sensor 3 includes a gas chamber 8, a first collimator 9-1, a second collimator 9-2, and a reflector 10. The gas chamber 8 is a cavity including an inlet and an outlet, used to hold the multi-component gas to be monitored. The reflector 10 is used to reflect the emitted light from the inlet into the gas chamber and out of the outlet back to the inlet. The first collimator 9-1 is installed at the inlet of the gas chamber, and the second collimator 9-2 is installed at the outlet of the gas chamber. The first collimator 9-1 is used to convert the divergent light beam entering the gas chamber from the inlet into a parallel light beam that exits from the outlet. The second collimator 9-2 is used to convert the divergent light beam entering the gas chamber from the outlet into a parallel light beam that exits from the inlet. Specifically, the gas chamber is a stainless steel cylinder with openings on both sides, which can ensure the strength of the gas measuring chamber while maximizing the opening area to facilitate gas entry into the measuring chamber. The gas chamber is used to hold the multi-component gas to be monitored. The reflector reflects the light emitted from the entrance port into the gas chamber, absorbed by the gas, and then emitted from the exit port back to the entrance port. The collimator converts the divergent light beam entering the gas chamber into a parallel light beam. The collimator can improve the measurement accuracy and efficiency of the sensor. In this invention, the parallel light beam processed by the collimator can pass through the gas chamber to reach the reflector as much as possible, thereby reducing the light intensity loss caused by beam divergence. When the light beam processed by the collimator passes through the gas sample, its path is predefined, ensuring that all beams pass through the gas volume chamber of the same length, which helps to calculate the gas concentration more accurately.

[0035] When the pulsed laser light enters the gas chamber 8 through the first collimator 9-1 at the entrance and is absorbed by the multi-component gas to be monitored, it exits through the second collimator 9-2 at the exit. After being reflected by the mirror 10, it enters the gas chamber 8 through the second collimator 9-2 at the exit and then exits through the first collimator 9-1 at the entrance. The photoelectric conversion module 4 detects the light signal emitted from the first collimator 9-1 at the entrance and performs photoelectric conversion before transmitting the peak light intensity of the pulsed laser signal of different wavelengths after absorption by the multi-component gas to the industrial control computer module 5. The industrial control computer module 5 calculates the concentration of the gas to be measured in the multi-component gas to be monitored based on the peak light intensity of the pulsed laser signal. Specifically, this invention uses an optical pulse module 2 to pulse the continuous light emitted by the laser from the laser source module 1, which is then transmitted to a gas-cell passive sensor 3. The light signal from the gas-cell passive sensor 3 is then transmitted to a photoelectric conversion module 4, converting the optical signal into an electrical signal. The final output is a peak light intensity, which is then calculated into multi-component gas concentrations by an industrial control computer module 5. It is worth noting that the calculation of gas concentration values ​​based on the peak light intensity mainly relies on Beer-Lambert's law (also known as Beer-Lambert's law). Beer-Lambert's law describes how the intensity of light changes with the concentration of the medium and the optical path length when passing through a medium. For gas concentration measurement, this law establishes the relationship between the input light intensity, the output light intensity, the gas concentration, and the effective path length of light through the gas. For example, when using a gas-cell passive sensor 3, the optical pulse module 2 pulses the laser emitted from the laser source module 1 and transmits it to the gas-cell passive sensor 3. The photoelectric conversion module 4 measures the first peak light intensity when there is no gas to be measured in the gas-cell passive sensor 3, and measures the second peak light intensity when there is gas to be measured in the gas-cell passive sensor 3. The industrial control computer module 5 calculates the absorption coefficient of the gas to be measured based on the first and second peak light intensity values. When the gas to be measured is mixed with other gases, when the photoelectric conversion module 4 detects the third peak light intensity after the laser has been absorbed by the mixed gas in the gas-cell passive sensor 3, the industrial control computer module 5 can calculate the concentration of the gas to be measured in the mixed gas based on the absorption coefficient and the third peak light intensity.

[0036] It is worth noting that when there are multiple gas chamber passive sensors, the measurement steps are the same as when using a single gas chamber passive sensor. That is, the absorption coefficient of each gas under different wavelengths of laser light is first calibrated using the gas chamber passive sensor, and then the concentration of the gas to be measured in the multi-component gas is measured based on the absorption coefficient.

[0037] For long-term, real-time, and continuous monitoring of oil and gas concentrations, this invention utilizes a fiber optic gas chamber passive sensor and a corresponding monitoring system to monitor the concentration of multiple gas components, achieving the goal of safe monitoring of storage tanks. This invention addresses the pain points of storage tank safety monitoring and can be effectively integrated with existing monitoring results for tank deformation, earthquakes, and settlement, enhancing the monitoring capabilities of existing systems. It has promising applications for subsequent multi-dimensional monitoring of storage tank safety, improving the overall safety monitoring level, and reducing the probability of tank farm accidents. This invention significantly reduces the operational risks of external floating roof tanks and simplifies the process of monitoring oil and gas concentrations within the sealed area of ​​the storage tank.

[0038] In one embodiment, such as Figure 4 The diagram shows a structural schematic of another multi-component gas concentration monitoring system provided by the present invention. The invention also includes a support platform 11, a speaker 12, and a display screen 13. The support platform 11 provides various modules with functions such as support installation, power supply, communication, control, heat dissipation, signal acquisition, data processing, and storage. The speaker 12 is connected to the industrial control computer module 5 and is used to issue an alarm when the concentration of the multi-component gas to be monitored exceeds a set threshold. The display screen 13 is connected to the industrial control computer module 5 and is used to display the concentration of the multi-component gas to be monitored. The input end of the optical pulse module 2 is connected to the industrial control computer module 5, and the output end of the optical pulse module 2 is connected to the laser source module 1. Pulse parameters are set on the industrial control computer module 5 to control the optical pulse module 2 to pulse the laser emitted from the laser source module 1 at a preset pulse frequency. The pulsed laser enters the sensor 3, is reflected by a reflector, and is detected by the photoelectric conversion module 4 to obtain the light intensity value, which is then sent to the industrial control computer module 5 for analysis and processing to obtain the multi-component gas concentration.

[0039] Specifically, the multi-component gas concentration monitoring system provided by the present invention includes a multi-component gas concentration monitoring host (i.e., a support platform 11, including a laser source module 1, a light pulse module 2, a photoelectric conversion module 4, and an industrial control computer module 5) and several chamber-type passive sensors 3. The chamber-type passive sensors 3 can perform high-precision, real-time monitoring of the oil and gas concentration within the sealed area of ​​the storage tank. The chamber-type passive sensors 3 are connected to a fiber optic junction box via optical fibers, and the fiber optic junction box is connected to the multi-component gas concentration monitoring host via a single-core optical fiber. The multi-component gas concentration monitoring host is connected to a speaker 12 and a display screen 13.

[0040] In one embodiment, such as Figure 5The diagram shows a laser signal transmission flowchart of a multi-component gas concentration monitoring system provided by this invention. The laser source module 1 includes several lasers. Specifically, when the absorption peaks of the gas to be measured are far apart, a single laser can achieve the function of this invention. When the absorption peaks of the gas to be measured are close together, multiple lasers are required to achieve the function of this invention. Because different component gases absorb laser light of different wavelengths differently, the laser source module can better monitor the concentration of multi-component gases by emitting laser light using multiple lasers of different wavelengths. Taking a multi-component gas containing propane and butane as an example, since propane and butane gases have relatively obvious absorption peaks under 1686nm and 1689nm laser light, respectively, lasers of 1686nm and 1689nm wavelengths are selected to monitor the absorption rates of propane and butane, respectively. In particular, if the wavelength distance is relatively large, for example, methane has a relatively obvious absorption peak at 1653nm, the methane concentration can be measured using a single laser. Since wavelengths of 1686nm and 1689nm are relatively close, to accurately distinguish them, lasers with wavelengths of 1686nm and 1689nm must be used to measure the concentrations of propane and butane separately. In other words, when using the multi-component gas concentration monitoring system of this invention to monitor a specific gas within a multi-component gas, a corresponding laser is required for monitoring.

[0041] In one embodiment, such as Figure 5 The diagram shows a laser signal transmission flowchart of a multi-component gas concentration monitoring system provided by the present invention. When the laser source module uses lasers of multiple wavelengths, the system further includes a first coupler 14. The first coupler 14 is used to couple lasers of different wavelengths emitted by the laser source module 1 into a single beam of light, which is then transmitted to the gas chamber 8 via a single-core optical fiber. The input end of the first coupler 14 is connected to the laser source module 1, and the output end of the first coupler 14 is connected to the gas chamber 8. Specifically, when the laser source module 1 includes lasers of 1686nm and 1689nm wavelengths, the first coupler 14 is a 1-to-2 coupler, which is used to couple the lasers emitted by the 1686nm and 1689nm lasers into a single beam of light, which is then transmitted to the gas chamber 8 via a single-core optical fiber. When the laser source module 1 includes lasers of 8 wavelengths, the first coupler 14 is an 8-to-1 coupler. The 8-to-1 coupler is used to couple the lasers emitted by the 8 lasers into a single beam of light and then transmit it to the gas chamber 8 through a single-core optical fiber.

[0042] In one embodiment, such as Figure 5The diagram shows a laser signal transmission flowchart of a multi-component gas concentration monitoring system provided by the present invention. The system further includes a second coupler 15. When the second coupler 15 receives incident light from the first coupler 14, it transmits the incident light to the gas chamber 8. When the second coupler 15 receives reflected light from the gas chamber 8, it transmits the reflected light to the photoelectric conversion module 4. Specifically, the second coupler 15 is used to distinguish between reflected light and incident light. The input end of the second coupler 15 is connected to the output end of the first coupler 14 and the first collimator 9-1 at the entrance of the gas chamber 8, respectively. The output end of the second coupler 15 is connected to the first collimator 9-1 at the entrance of the gas chamber 8 and the photoelectric conversion module 4, respectively. It is worth noting that when the laser source module 1 uses only one wavelength laser, the second coupler 15 receives the incident light from the optical pulse module 2 and transmits the incident light to the gas chamber 8; when the second coupler 15 receives the reflected light from the gas chamber 8, the second coupler 15 transmits the reflected light to the photoelectric conversion module 4. At this time, the input end of the second coupler 15 is connected to the output end of the optical pulse module 2 and the first collimator 9-1 at the entrance of the gas chamber 8, respectively, and the output end of the second coupler 15 is connected to the first collimator 9-1 at the entrance of the gas chamber 8 and the photoelectric conversion module 4, respectively.

[0043] In one embodiment, such as Figure 5 The diagram shows a laser signal transmission flowchart of a multi-component gas concentration monitoring system provided by the present invention. When there are N gas chambers, the system further includes a third coupler 16, which divides the incident light from the second coupler 15 into N equal parts and transmits them to each gas chamber, where N is a positive integer greater than 1. Specifically, when N = 8, the third coupler is an 8-to-1 coupler. The 8-to-1 coupler is used to distribute the optical signal to 8 gas chambers. The optical signal transmitted from a single-core optical fiber is divided into eight beams by the 8-to-1 coupler, and each beam is transmitted to a gas chamber-type passive sensor.

[0044] In one embodiment, the system further includes a time-delay fiber connected to the output of each laser to distinguish lasers of different wavelengths in time. Specifically, the time-delay fiber introduces a time delay. Such fibers are commonly used in fiber optic communication systems, fiber optic sensors, fiber optic lasers, and other optical systems to achieve specific functional or performance optimizations. In this invention, the time-delay fiber provides a precise time delay. Connecting the time-delay fiber to the back end of the laser allows for the time-separation of pulses emitted by two lasers. The two beams are then combined into a single beam via a splitter and fed into a single-core fiber, while simultaneously preventing optical signal aliasing.

[0045] In one embodiment, single-core optical fiber is used for optical signal transmission between the various hardware components of the system. The single-core optical fiber serves as the signal transmission link, transferring the optical signal from a 1-to-2 coupler to a 1-to-8 coupler. The main advantages of single-core optical fiber include cost-effectiveness, ease of management, resistance to electromagnetic interference, long data transmission distance, fewer bit errors, and high network efficiency.

[0046] This invention uses an optical pulse module to pulse the continuous light emitted by the laser in the laser source module. A coupler couples the pulsed light from different lasers into a time-delay fiber, and then the coupler distributes the beam of light into several fibers. The optical signal is transmitted to the sensor via the time-delay fiber. Each fiber is followed by a time-delay fiber of progressively increasing length, enabling the differentiation of the optical signal from a single sensor. The optical signal reflected by the internal mirror of the sensor is transmitted through the fiber to the photoelectric conversion module, converting the optical signal into an electrical signal. The final output is the peak light intensity, which is then calculated by an algorithm to determine the concentration of multiple gas components.

[0047] This invention utilizes a fiber optic gas chamber passive sensor and a corresponding monitoring system to monitor the concentration of multi-component gases, achieving the goal of safety monitoring of storage tanks. This invention addresses the pain points in storage tank safety monitoring and can be effectively integrated with existing monitoring results for tank deformation, earthquakes, and settlement, enhancing the monitoring capabilities of existing systems. It shows promising application prospects for subsequent multi-dimensional monitoring of storage tank safety, improving the overall safety monitoring level, and reducing the probability of tank farm accidents. This invention significantly reduces the operational risks of external floating roof tanks and simplifies the process of monitoring oil and gas concentrations within the sealed area of ​​the storage tank.

[0048] In one embodiment, the calculation of the concentration of each component gas in the multi-component gas to be monitored includes:

[0049] The absorption coefficients of each component gas under different wavelengths of laser light were pre-calibrated using a multi-component gas concentration monitoring system.

[0050] The concentrations of each component gas in the multi-component gas to be monitored are calculated based on the absorption coefficient and the peak intensity of the pulsed laser signal.

[0051] Specifically, this invention requires pre-calibrating the absorption coefficient of each gas to be tested under different wavelengths of laser light. The absorption coefficient reflects the change in optical power of the gas before and after laser absorption when the laser passes through the gas chamber. With the gas chamber empty of the gas to be tested and filled with a standard concentration of the gas to be tested, the peak intensity of the laser pulse echo signal at different wavelengths is collected and measured. Substituting these peak intensity values ​​into the absorption coefficient calculation formula yields the absorption coefficient of the gas to be tested at different wavelengths.

[0052] In one embodiment, the peak intensity I′ of the laser beam after absorption by the gas to be measured can be expressed as:

[0053] I′=Ie -αCL ;

[0054] Where I is the peak intensity of the laser light before absorption by the gas being tested, α is the absorption coefficient corresponding to the laser wavelength, C is the concentration of the gas being tested, and L is the optical path (representing the distance the laser travels in the gas being tested). In this invention, L is twice the distance from the inlet to the outlet of the gas chamber. This invention increases the laser optical path by adding a reflector to the sensor, making the monitoring results more accurate.

[0055] In one embodiment, the absorption coefficient is calculated using the following formula:

[0056]

[0057] Where C is the gas concentration, I is the peak light intensity of the laser before absorption by the gas to be tested, I′ is the peak light intensity of the laser after absorption by the gas to be tested, and L is the optical path length. It is worth noting that this invention calculates the concentration of each component gas in the multi-component gas to be tested using the absorption coefficients of a standard gas to be tested at known concentrations under pulsed lasers of different wavelengths; that is, C is a known value in this formula.

[0058] In one embodiment, the present invention can monitor the concentration of one gas in a multi-component gas, or it can monitor the concentration of two gases in a multi-component gas whose absorption peaks are close to each other.

[0059] Specifically, taking the monitoring of methane gas concentration in a multi-component gas as an example, the absorption coefficient α0 of methane gas under a pulsed laser with a wavelength λ0 is pre-calibrated using a standard methane gas of known concentration. Let I... λ0 I' is the intensity of a pulsed laser with wavelength λ0 when the gas chamber is not filled with the multi-component gas to be monitored. λ0When the gas chamber is filled with the multi-component gas to be tested, the intensity of the pulsed laser with wavelength λ0 is given, and C0 is the concentration of the methane gas to be tested in the multi-component gas. The concentration of the methane gas to be tested in the multi-component gas can be obtained by using the concentration calculation formula.

[0060] In one embodiment, when monitoring the concentration of one gas in a multi-component gas, the following concentration calculation formula is used:

[0061]

[0062] Where α0 is the absorption coefficient of methane gas under pulsed laser light at wavelength λ0, pre-calibrated using standard methane gas of known concentration, and I' λ0 When the gas chamber is filled with the multi-component gas to be tested, the intensity of the pulsed laser light with wavelength λ0 is I. λ0 The intensity of the pulsed laser with wavelength λ0 is given when the gas chamber is not filled with the multi-component gas to be monitored. The intensity is expressed in decibels, and L is the optical path length.

[0063] Specifically, taking the monitoring of propane and butane gas concentrations in a multi-component gas as an example, the absorption coefficients α1 and α2 of propane gas under pulsed laser light at wavelengths λ1 and λ2, and the absorption coefficients α3 and α4 of butane gas under pulsed laser light at wavelengths λ1 and λ2, are pre-calibrated using standard propane and butane gases of known concentrations. Let I... λ1 I λ2 These represent the pulsed laser intensities at wavelengths λ1 and λ2 when the gas chamber is not filled with the multi-component gas to be monitored, respectively. λ1 、I' λ2 λ1 and λ2 are the pulsed laser intensities at wavelengths λ1 and λ2 respectively when the gas chamber is filled with the multi-component gas to be tested. C1 and C2 are the gas concentrations of propane and butane in the multi-component gas to be tested, respectively. The gas concentrations of propane and butane can be calculated using the concentration calculation formula.

[0064] In one embodiment, when monitoring the concentrations of two gases in a multi-component gas, the following concentration calculation formula is used:

[0065]

[0066] The light intensity is expressed in decibels.

[0067] Specifically, the wavelengths of the two lasers are λ1 = 1686 nm and λ2 = 1689 nm, respectively, and the optical path L of the gas cell unit is 120 cm. Two passive gas cell sensors are connected to the system to measure and analyze the multi-component gases in the first and second gas cells. The absorption coefficients of propane and butane to pulsed laser light at wavelengths of 1686 nm and 1689 nm are pre-calibrated using the multi-component gas concentration monitoring system of this invention as follows: α1 = 0.064275512, α2 = 0.060584013, α3 = 0.064709806, and α4 = 0.109659235, respectively. When the first gas cell is not filled with the multi-component gas to be monitored, the peak light intensity of the pulse echo signal curves at wavelengths of 1686 nm and 1689 nm are respectively I... λ1 =23.793dB, I λ2 =25.593dB. When the first chamber is filled with a mixture of propane and butane at standard concentrations of 10% and 5% respectively, the peak light intensity is I' λ1 =22.751dB, I' λ2 =24.329dB. Substituting these data into the concentration calculation formula, the concentration of the mixed gas can be calculated as: 10.3809% propane and 5.7914% butane, that is, propane 103809ppm and butane 57914ppm.

[0068] In one embodiment, when monitoring the concentrations of four gases in a multi-component gas, the following concentration calculation formula is used:

[0069]

[0070] Wherein, C1, C2, C3, and C4 represent the concentrations of four analyte gases in the multi-component gas to be monitored; α1, α2, α3, and α4 represent the absorption coefficients of pulsed laser light at wavelengths λ1, λ2, λ3, and λ4 for the analyte gas with concentration C1; α5, α6, α7, and α8 represent the absorption coefficients of pulsed laser light at wavelengths λ1, λ2, λ3, and λ4 for the analyte gas with concentration C2; α9, α... 10 α 11 α 12 α represents the absorption coefficient of the test gas with a concentration of C3 under pulsed laser light at wavelengths λ1, λ2, λ3, and λ4, respectively; 13 α 14 α 15 α 16 I represents the absorption coefficients of the analyte gas with a concentration of C4 under pulsed laser light at wavelengths λ1, λ2, λ3, and λ4, respectively. λ1 The intensity of a pulsed laser with wavelength λ1 when the gas chamber is not filled with the multi-component gas to be monitored; I' λ1The intensity of the pulsed laser with wavelength λ1 when the gas chamber is filled with the multi-component gas to be tested; λ2 The intensity of a pulsed laser with wavelength λ2 when the gas chamber is not filled with the multi-component gas to be monitored; I' λ2 The intensity of a pulsed laser with wavelength λ2 is used when the gas chamber is filled with the multi-component gas to be tested. λ3 The intensity of a pulsed laser with wavelength λ3 when the gas chamber is not filled with the multi-component gas to be monitored; I' λ3 The intensity of a pulsed laser with wavelength λ3 is used when the gas chamber is filled with the multi-component gas to be tested. λ4 The intensity of a pulsed laser with wavelength λ4 when the gas chamber is not filled with the multi-component gas to be monitored; I' λ4 The intensity of a pulsed laser with a wavelength of λ4 is used when the gas chamber is filled with the multi-component gas to be tested.

[0071] In one embodiment, when monitoring the concentrations of n gases in a multi-component gas, the following concentration calculation formula is used:

[0072]

[0073] Among them, C1, C2, ..., C n Let α1, α2, ..., α3 be the concentrations of n analytes in the multi-component gas to be monitored. n The test gas with concentration C1 is measured at wavelengths λ1, λ2, ..., λ... n The absorption coefficient of the pulsed laser under the given conditions; α n+1 α n+2 ..., α n+n The test gas with a concentration of C2 is measured at wavelengths λ1, λ2, ..., λ3. n The absorption coefficient of the pulsed laser under the given conditions; α n×(n-1)+1 α n×(n -1)+2 ..., α n×n The concentrations are C n The gas to be tested is at wavelengths λ1, λ2, ..., λ n The absorption coefficient of the pulsed laser under the specified conditions; I λ1 The intensity of a pulsed laser with wavelength λ1 when the gas chamber is not filled with the multi-component gas to be monitored; I' λ1 The intensity of the pulsed laser with wavelength λ1 when the gas chamber is filled with the multi-component gas to be tested; λ2 The intensity of a pulsed laser with wavelength λ2 when the gas chamber is not filled with the multi-component gas to be monitored; I' λ2 The intensity of a pulsed laser with wavelength λ2 is used when the gas chamber is filled with the multi-component gas to be tested. λn The wavelength is λ when the gas chamber is not filled with the multi-component gas to be monitored. n The intensity of the pulsed laser light; I' λn When the gas chamber is filled with the gas to be measured from the multi-component gas, the wavelength is λ.n Pulsed laser light intensity.

[0074] Generally, one type of gas corresponds to one specific wavelength laser. That is, when monitoring the concentration of one gas, a specific wavelength laser is prepared; when monitoring the concentration of two gases, two specific wavelength lasers are prepared; when monitoring the concentration of four gases, four specific wavelength lasers are prepared; and when monitoring the concentration of n gases, n specific wavelength lasers are prepared.

[0075] In one embodiment, such as Figure 6 As shown, the present invention also provides a method for monitoring the concentration of a multi-component gas, wherein the method is implemented based on the multi-component gas concentration monitoring system described in any of the above-mentioned embodiments, and the method includes:

[0076] S601. Acquire the peak intensity of the pulsed laser signal after absorption by the multi-component gas to be monitored;

[0077] S602. Calculate the concentration of the gas to be measured in the multi-component gas to be monitored based on the peak intensity of the pulsed laser signal.

[0078] Since the principle of the multi-component gas concentration monitoring method of the present invention is similar to that of the aforementioned multi-component gas concentration monitoring system, the implementation of the multi-component gas concentration monitoring method can refer to the implementation of the aforementioned multi-component gas concentration monitoring system, and the repeated parts will not be described again.

[0079] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0080] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0081] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0082] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0083] In the description of this specification, the references to terms such as "an embodiment," "a specific embodiment," "some embodiments," "for example," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-component gas concentration monitoring system, characterized in that, The system includes: a laser source module, a light pulse module, a gas chamber passive sensor, a photoelectric conversion module, and an industrial control computer module; The optical pulse module pulses the laser output from the laser source module and transmits it to the gas chamber passive sensor. The gas chamber passive sensor includes a gas chamber, a first collimator, a second collimator, and a reflector. The gas chamber is a cavity including an inlet and an outlet. The gas chamber is used to hold the multi-component gas to be monitored. The reflector is used to reflect the outgoing light that enters the gas chamber from the inlet and exits from the outlet back to the inlet and exits. The first collimator is installed at the inlet of the gas chamber, and the second collimator is installed at the outlet of the gas chamber. The first collimator is used to convert the divergent beam entering the gas chamber from the inlet into a parallel beam that exits from the outlet. The second collimator is used to convert the divergent beam entering the gas chamber from the outlet into a parallel beam that exits from the inlet. When the pulsed laser light enters the gas chamber through the first collimator at the entrance and is absorbed by the multi-component gas to be monitored, it exits through the second collimator at the exit. After being reflected by the mirror, it enters the gas chamber through the second collimator at the exit and then exits through the first collimator at the entrance. The photoelectric conversion module detects the light signal emitted from the first collimator at the entrance and performs photoelectric conversion before transmitting the peak light intensity of the pulsed laser signal after absorption by the multi-component gas to the industrial control computer module. The industrial control computer module calculates the concentration of the gas to be measured in the multi-component gas to be monitored based on the peak light intensity of the pulsed laser signal.

2. The system as described in claim 1, characterized in that, The calculated concentrations of the gas to be measured in the multi-component gas to be monitored include: The absorption coefficient of the gas to be tested to pulsed laser is pre-calibrated using a multi-component gas concentration monitoring system. The concentration of the gas to be measured in the multi-component gas to be monitored is calculated based on the absorption coefficient and the peak intensity of the pulsed laser signal.

3. The system as described in claim 1, characterized in that, When the laser source module uses lasers of multiple wavelengths, the system further includes a first coupler, which is used to couple different wavelength lasers after they have been pulsed by the optical pulse module and transmit them to the gas chamber.

4. The system as described in claim 3, characterized in that, The system further includes a second coupler. When the second coupler receives incident light from the first coupler, the second coupler transmits the incident light to the gas chamber. When the second coupler receives reflected light from the gas chamber, the second coupler transmits the reflected light to the photoelectric conversion module.

5. The system as described in claim 4, characterized in that, When there are N air chambers, the system further includes a third coupler, which divides the incident light from the second coupler into N equal parts and transmits them to each air chamber, where N is a positive integer greater than 1.

6. The system as described in claim 1, characterized in that, The system also includes a time-delay fiber connected to the output of each laser to distinguish lasers of different wavelengths in time.

7. The system as described in claim 1, characterized in that, The air-cell passive sensor transmits optical signals to the laser source module and the photoelectric conversion module using a single-core optical fiber.

8. The system as described in claim 1, characterized in that, The system also includes a display screen, which is connected to the industrial control computer module and is used to display the concentration of the multi-component gas to be monitored.

9. The system as described in claim 1, characterized in that, The system also includes a speaker connected to the industrial control computer module, which is used to issue an alarm when the concentration of the multi-component gas to be monitored exceeds a set threshold.

10. A method for monitoring the concentration of a multi-component gas, wherein the method is implemented based on the multi-component gas concentration monitoring system according to any one of claims 1-9, characterized in that, include: The peak intensity of the pulsed laser signal after absorption by the multi-component gas to be monitored is collected; The concentration of the gas to be measured in the multi-component gas to be monitored is calculated based on the peak intensity of the pulsed laser signal.

Images