Gas component online monitoring system based on pulse flame luminosity

Abstract

The invention relates to the technical field of gas monitoring, and provides a pulse flame luminosity-based gas component online monitoring system, which comprises a monitoring device, and a PFPD detector is erected in the monitoring device. A bypass gas outlet head, a product gas inlet head, a combustion-supporting air inlet head and a high-purity hydrogen inlet head are fixedly installed at the front end of the monitoring device, and one end of the PFPD detector is fixedly connected with a signal collecting and processing module. According to the scheme, based on the principle of a pulse flame photometric detector, improvement is carried out on the basis of the pulse flame photometric detector, a high-precision small-range passivated airflow EFC controller is adopted to control the flow of sample gas, the response speed is high, and the material change of total sulfur, total phosphorus and total carbon in the sample gas can be monitored online in real time; the method has the detection capability of real-time detection, can provide a good online detection scheme for some occasions with high data response requirements, and can better guide the process to carry out production regulation and control.

Description

Technical Field

[0001] This invention relates to the field of gas monitoring technology, and in particular to an online gas composition monitoring system based on pulsed flame photometry. Background Technology

[0002] Flame photometric detectors (FPDs) are classic detectors with high selectivity and sensitivity to sulfur and phosphorus compounds, and are widely used in gas chromatographs and online process analysis systems. Traditional FPDs typically employ a single-flame design, and their flames are extremely sensitive to fluctuations in gas flow rate. Fluctuations in the concentration or pressure of hydrocarbons in the process gas can easily alter the flame state or even cause the flame to extinguish. In addition, high concentrations of hydrocarbons can produce a severe quenching effect, significantly suppressing the characteristic luminescence intensity of sulfur and phosphorus, leading to distortion or even complete annihilation of the measurement signal. Their optical path collection efficiency is limited, and they cannot effectively distinguish characteristic signals from background noise, which restricts their application in the field of trace analysis.

[0003] Most traditional FPDs are single-channel designs, capable of detecting only one substance (sulfur or phosphorus) at a time. To detect simultaneously, two independent systems are required, which is costly and space-consuming. In addition, their data output frequency is low (usually measured in seconds or even minutes), making it difficult to capture rapid changes in gas composition during the process and failing to meet the urgent need for real-time online monitoring in modern precision manufacturing.

[0004] To address the aforementioned issues, while some technologies have proposed improved solutions such as dual-flame photometric detection (DFPD), which uses an oxygen-rich slave flame to ignite a hydrogen-rich main flame above, thus improving fire resistance to some extent, they have not fundamentally solved the problems of quenching effect, detection limit, simultaneous measurement of dual channels, and ultra-high response speed. Therefore, there is an urgent need for a new type of online monitoring system that can combine the advantages of various flame photometric detection technologies, possessing extremely high stability, anti-interference ability, ultra-low detection limit, multi-component simultaneous detection capability, and millisecond-level fast response speed, to meet the stringent requirements of accurate, real-time, and online monitoring of trace hazardous substances in fields such as petrochemicals, natural gas, and environmental monitoring.

[0005] Therefore, we have made improvements to this by proposing an online gas composition monitoring system based on pulsed flame photometry. Summary of the Invention

[0006] The purpose of this invention is to provide an online gas composition monitoring system based on pulsed flame photometry to solve the problems mentioned in the background art.

[0007] To achieve the above-mentioned objectives, this invention provides an online gas composition monitoring system based on pulsed flame photometry, comprising a monitoring device. A PFPD detector is installed inside the monitoring device. A bypass gas outlet, a product gas inlet, a combustion air inlet, and a high-purity hydrogen inlet are fixedly installed at the front end of the monitoring device. A signal acquisition and processing module is fixedly connected to one end of the PFPD detector. The PFPD detector includes a fixedly installed lower detector body and an upper detector body. A quartz combustion chamber is fixedly installed inside the upper detector body. Two mutually perpendicular reflectors are installed in the quartz combustion chamber. A quartz light guide tube I and a quartz light guide tube II are respectively installed on opposite sides of the two reflectors on the upper detector body. A photomultiplier tube I is fixedly connected to the outer end of the first quartz light guide tube, and the outer end of the second quartz light guide tube is connected to… A photomultiplier tube is connected to the second quartz light guide tube, and a triangular reflecting prism is fixedly installed between the second quartz light guide tube and the second photomultiplier tube. The interior of the quartz combustion chamber is connected from top to bottom to include an ignition chamber, an ignition chamber, and a combustion chamber. An ignition wire is fixedly installed on the ignition chamber, and an exhaust pipe is fixedly installed at the top of the ignition chamber. A quartz capillary column is installed at the bottom of the quartz combustion chamber, and the bottom of the quartz capillary column is connected to a product gas path. The end of the product gas path is fixedly installed to a product gas inlet head, and the middle of the product gas path is fixedly installed to a bypass gas outlet head through a T-junction. A combustion chamber inlet pipe and an ignition chamber inlet pipe are also fixedly connected to one side of the quartz combustion chamber. An airflow EFC ​​controller is installed on the gas path connected to the combustion chamber inlet pipe and the ignition chamber inlet pipe. The airflow EFC ​​controller is also fixedly connected to the combustion air inlet head and the high-purity hydrogen inlet head.

[0008] As a further embodiment of the present invention, the number of airflow EFC ​​controllers is two. The two airflow EFC ​​controllers respectively modulate the airflow of the hydrogen-rich / air mixture inside the combustion chamber intake pipe and the air-rich / hydrogen mixture inside the ignition chamber intake pipe, so that the PFPD detector has a highly stable airflow, thereby generating a highly stable pulse flame.

[0009] As a further embodiment of the present invention, the interiors of the airflow EFC ​​controller, the bypass gas outlet, and the product gas inlet are all passivated.

[0010] As a further embodiment of the present invention, filters are installed inside the first quartz light guide tube and the second quartz light guide tube, and the filters inside the first quartz light guide tube and the second quartz light guide tube are respectively a sulfur type filter and a phosphorus type filter.

[0011] As a further embodiment of the present invention, the airflow EFC ​​controller includes an outer cylinder, with two air inlet pipes fixedly connected to the bottom end of the outer cylinder. The air inlet pipes are connected to a combustion air inlet head and a high-purity hydrogen inlet head. A solenoid valve is fixedly installed inside the air inlet pipe. A hollow inner cylinder is rotatably installed inside the outer cylinder. A knob is fixedly installed at one end of the inner cylinder, and an air outlet pipe is fixedly connected to the other end of the inner cylinder. Bearings are fixedly installed at both ends of the inner wall of the inner cylinder, and a fan blade is rotatably connected between the two bearings.

[0012] As a further embodiment of the present invention, the inner cylinder has four sets of air inlets on its side wall, and the four sets of air inlets are an array of hollow patterns with gradually increasing diameters.

[0013] As a further embodiment of the present invention, the fan blade is composed of multiple spiral blades, and the fan blade is driven to rotate by the airflow entering the air intake pipe.

[0014] As a further embodiment of the present invention, the signal acquisition and processing module is a high-speed acquisition circuit for pA / nA analog current signals, a PMT high-voltage output circuit (0-800V DC) and a software integration module for its signal processing circuit.

[0015] The online gas composition monitoring system based on pulsed flame photometry provided by this invention has the following advantages: 1. This solution is based on the principle of pulse flame photometric detector and is an improvement upon it. It uses a high-precision, small-range, passivated airflow EFC ​​controller to control the sample gas flow rate. It can realize real-time online detection of total sulfur, total phosphorus, and other substances in gases with low hydrocarbon content (nitrogen, hydrogen, helium, air, etc.). It has a fast response speed, generating 3 measurement results per second. The analyzer has a fast response speed and can monitor the changes in total sulfur, total phosphorus, and total carbon in the sample gas in real time. It has real-time detection capability and can provide a good online detection solution for some occasions with high data response requirements, better guiding the process for production control.

[0016] 2. The traditional flame photometric detector has been improved by combining the advantages of single-flame and dual-flame flame photometric detectors. This not only solves the problem of easy flameout (caused by airflow fluctuations or large solvents entering the flame leading to oxygen deficiency and flameout), but also optimizes the quenching problem, minimizing the quenching reaction. It also solves the problem of low detection limit. The dual-channel structure design and the use of triangular reflectors make the detector structure more compact and smaller in size. The loss of emitted photons by the analyte is reduced, and the collection efficiency of photons is increased, compensating for the disadvantage of long light transmission paths.

[0017] 3. By installing components in the intake air lines of the combustion chamber and ignition chamber, the PFPD detector achieves highly stable airflow by modulating the flow of the hydrogen-rich / air mixture inside the combustion chamber intake pipe and the air-rich / hydrogen mixture inside the ignition chamber intake pipe. This results in a highly stable pulse flame. In addition, an EFC component is installed to modulate the flow of the product gas, ensuring that the product gas enters the detector's combustion chamber at a stable gas flow rate. Each gas path is precisely controlled by a high-precision EPC component with a small range, ensuring accurate and stable airflow into the combustion chamber and ignition chamber. Each airflow can be controlled to produce pulse flames of different frequencies for the product. Attached Figure Description

[0018] 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.

[0019] Figure 1 A schematic diagram of an online gas composition monitoring system based on pulsed flame photometry provided for this application; Figure 2 A schematic diagram of the structure of an online gas composition monitoring system based on pulsed flame photometry provided in this application. Figure 1 ; Figure 3 A schematic diagram of the structure of an online gas composition monitoring system based on pulsed flame photometry provided in this application. Figure 2 ; Figure 4 The main view of the PFPD detector structure of an online gas composition monitoring system based on pulsed flame photometry provided in this application; Figure 5 A top view of the PFPD detector structure of an online gas composition monitoring system based on pulsed flame photometry provided in this application; Figure 6 A schematic diagram of the airflow EFC ​​controller structure of an online gas composition monitoring system based on pulse flame photometry provided in this application; Figure 7 An explosion diagram of the airflow EFC ​​controller of an online gas composition monitoring system based on pulse flame photometry provided in this application; Figure 8 A cross-sectional view of the airflow EFC ​​controller structure of an online gas composition monitoring system based on pulsed flame photometry provided in this application; Figure 9A schematic diagram of the inner cylinder structure of a gas composition online monitoring system based on pulse flame photometry provided in this application; Figure 10 A schematic diagram of the fan blade structure for an online gas composition monitoring system based on pulsed flame photometry provided in this application; Figure 11 The pulsed flame emission spectrum provided for this application.

[0020] In the diagram: 1. Monitoring equipment; 2. PFPD detector; 21. Lower body of detector; 22. Upper body of detector; 23. Quartz combustion chamber; 24. Quartz capillary column; 25. Ignition wire; 26. Exhaust pipe; 27. Quartz light guide tube I; 28. Filter; 29. ​​Photomultiplier tube I; 210. Quartz light guide tube II; 211. Triangular reflecting prism; 212. Photomultiplier tube II; 3. Combustion chamber air inlet pipe; 4. Ignition chamber air inlet pipe; 5. Airflow EFC ​​controller; 51. Outer cylinder; 52. Air inlet pipe; 53. Solenoid valve; 54. Inner cylinder; 55. Knob; 56. Air outlet pipe; 57. Air inlet hole; 58. Bearing; 59. Fan blade; 6. Bypass gas outlet; 7. Product gas inlet; 8. Combustion air inlet; 9. High-purity hydrogen inlet; 10. Signal acquisition and processing module. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0022] like Figures 1-11As shown, this embodiment proposes an online gas composition monitoring system based on pulsed flame photometry, including a monitoring device 1. A PFPD detector 2 is installed inside the monitoring device 1. A bypass gas outlet 6, a product gas inlet 7, a combustion air inlet 8, and a high-purity hydrogen inlet 9 are fixedly installed at the front end of the monitoring device 1. A signal acquisition and processing module 10 is fixedly connected to one end of the PFPD detector 2. The PFPD detector 2 includes a fixedly installed lower detector body 21 and an upper detector body 22. A signal acquisition and processing module 10 is fixedly installed inside the upper detector body 22. The quartz combustion chamber 23 is equipped with two mutually perpendicular reflectors. On the detector upper body 22, quartz light guide tube 1 27 and quartz light guide tube 210 are respectively installed on opposite sides of the two reflectors. A photomultiplier tube 1 29 is fixedly connected to the outer end of quartz light guide tube 1 27, and a photomultiplier tube 212 is connected to the outer end of quartz light guide tube 210. A triangular reflecting prism 211 is fixedly installed between quartz light guide tube 210 and photomultiplier tube 212. The interior of the quartz combustion chamber 23, from top to bottom, connects the ignition chamber, the pilot ignition chamber, and the combustion chamber. The quartz combustion chamber 23 has an ignition wire 25 fixedly installed on its top. An exhaust pipe 26 is fixedly installed at the top of the ignition chamber. A quartz capillary column 24 is installed at the bottom of the quartz combustion chamber 23, and the bottom of the capillary column 24 is connected to a product gas path. The end of the product gas path is fixedly installed to a product gas inlet head 7. A bypass gas outlet head 6 is fixedly installed in the middle of the product gas path via a tee. A combustion chamber inlet pipe 3 and an ignition chamber inlet pipe 4 are also fixedly connected to one side of the quartz combustion chamber 23. Airflow EFC ​​controllers are installed on the gas paths connected to the combustion chamber inlet pipe 3 and the ignition chamber inlet pipe 4. The airflow EFC ​​controller 5 is simultaneously connected and fixed to the combustion air inlet 8 and the high-purity hydrogen inlet 9. The monitoring device 1 serves as the main housing, with the PFPD detector 2 as its core. The front-end interface is used to connect to various gas sources and discharge bypass gases. The PFPD detector 2 adopts a split design with a lower body 21 and an upper body 22 for easy assembly and maintenance. Its core component, the quartz combustion chamber 23, adopts a special structure that divides the ignition, pilot ignition, and combustion functions into zones, improving the stability of the flame and the reliability of ignition. The reflectors on both sides and the quartz light guide tubes (27, 210) constitute the optical path system, which is used to efficiently collect the characteristic emission light generated by the combustion of sulfur, phosphorus, and other substances in the flame. The use of the triangular reflecting prism 211 compacts the optical path, reducing space occupation and light loss. The quartz capillary column 24 is used to guide the sample gas into the combustion chamber through a specific flow path. The airflow EFC ​​controller 5 precisely controls the flow rate and ratio of the combustion gases hydrogen and air leading to the combustion chamber and pilot ignition chamber, which is the key to generating a stable pulse flame.

[0023] There are two airflow EFC ​​controllers 5. The two airflow EFC ​​controllers 5 modulate the airflow of the hydrogen-rich / air mixture inside the combustion chamber inlet pipe 3 and the air-rich / hydrogen mixture inside the ignition chamber inlet pipe 4, respectively, so that the PFPD detector 2 has a highly stable airflow, thereby generating a highly stable pulse flame. The two airflow EFC ​​controllers 5 are independently and precisely controlled. One controller is responsible for regulating the airflow entering the main combustion chamber, which is usually a mixture rich in hydrogen and a moderate amount of air, to generate a high-temperature reducing flame, so that sulfur and phosphorus compounds are fully decomposed and excited to emit light. The other controller is responsible for regulating the airflow entering the ignition chamber, which is usually a mixture rich in air and a moderate amount of hydrogen, to form a stable and extinguishable small flame, which reliably ignites the mixture in the main combustion chamber. This dual airflow independent modulation technology ensures that even when the sample airflow or concentration fluctuates, the frequency, intensity and chemical environment of the pulse flame remain highly stable, which is the basis for achieving high-precision and high-repeatability detection.

[0024] The internal components of the airflow EFC ​​controller 5, bypass gas outlet 6, and product gas inlet 7 are all passivated. Passivation typically involves silanization or coating with inert materials such as quartz or stainless steel to form a dense protective film on the metal or alloy surface, making it chemically inert. Passivating the internal flow path of the airflow EFC ​​controller 5, bypass gas outlet 6, and product gas inlet 7 can greatly reduce the adsorption and catalytic decomposition of trace active target substances, especially sulfur and phosphorus compounds, on the surfaces of these components. This can prevent the sample from being lost or transformed before entering the detector, ensuring the authenticity and accuracy of the measurement results.

[0025] Quartz light guide tube 1 (27) and quartz light guide tube 2 (210) are equipped with filters 28. Filters 28 are a sulfur-type filter and a phosphorus-type filter, respectively, inside quartz light guide tube 1 (27) and quartz light guide tube 2 (210). Filter 28 is a key element for spectral selection. Sulfur compounds burning in a hydrogen-rich flame produce a characteristic emission spectrum S2 near a wavelength of 394 nm, while phosphorus compounds produce a characteristic emission spectrum HPO near a wavelength of 526 nm. The sulfur-type filter is specifically used to transmit light near 394 nm while blocking other wavelengths of light, such as background light from hydrocarbons. The phosphorus-type filter specifically transmits light near 526 nm. By placing these filters in two independent optical paths, quartz light guide tubes 1 and 2, photomultiplier tube 1 (29) specifically detects the sulfur signal, and photomultiplier tube 2 (212) specifically detects the phosphorus signal. This design achieves simultaneous, separate, and selective detection of sulfur and phosphorus, greatly improving the system's multifunctionality and analytical efficiency.

[0026] The airflow EFC ​​controller 5 includes an outer cylinder 51. Two air inlet pipes 52 are fixedly connected to the bottom of the outer cylinder 51. The air inlet pipes 52 are connected to a combustion air inlet head 8 and a high-purity hydrogen inlet head 9. A solenoid valve 53 is fixedly installed inside the air inlet pipe 52. A hollow inner cylinder 54 is rotatably installed inside the outer cylinder 51. A knob 55 is fixedly installed at one end of the inner cylinder 54, and an air outlet pipe 56 is fixedly connected to the other end of the inner cylinder 54. Bearings 58 are fixedly installed at both ends of the inner wall of the inner cylinder 54, and a fan blade 59 is rotatably connected between the two bearings 58. 51 is a fixed housing. Two air inlet pipes 52 are connected to hydrogen and air respectively. The solenoid valve 53 is used to quickly open or close the gas path and is one of the key actuators to realize the "pulse" flame. The hollow inner cylinder 54 can be rotated by the knob 55 and is the core component for adjusting the airflow. The exhaust pipe 56 delivers the mixed gas to the combustion chamber or ignition chamber. The bearing 58 supports the fan blade 59 to rotate freely. The fan blade 59 can be used as a flow sensing element, and its rotation speed is proportional to the airflow speed, i.e., the flow rate. It also mixes the two gases thoroughly in the inner cylinder 54.

[0027] The inner cylinder 54 has four sets of air inlets 57 on its side wall. The four sets of air inlets 57 are an array of hollow patterns with gradually increasing diameters. The gradually increasing air inlets 57 form a precise flow regulating valve. When the inner cylinder 54 is rotated, the air inlets 57 of different sizes will align with the outlet of the air inlet pipe 52. When the small diameter holes are aligned, the flow area is small and the flow rate is small; when the large diameter holes are aligned, the flow area is large and the flow rate is large. This design allows the operator to make manual coarse adjustments by using the knob 55 to set an approximate flow range, providing a stable and precisely settable basic airflow for the system.

[0028] The fan blade 59 is composed of multiple spiral blades. The fan blade 59 is driven to rotate by the airflow entering the air intake pipe 52. The spiral blade 59 is pushed to rotate by the airflow, and its rotation speed directly reflects the magnitude of the instantaneous flow rate. This rotation speed can be detected by optical or magnetic sensors (not shown in the diagram), but is a standard configuration of this type of controller and converted into an electrical signal. This feedback signal is compared with the preset flow rate value, and the switching duty cycle of the solenoid valve 53 is dynamically adjusted by the control circuit to achieve closed-loop precise control of the flow rate. This allows the airflow to resist the influence of factors such as upstream pressure fluctuations and maintain a high degree of stability. In addition, while the fan blade 59 is rotating, it can also fully mix one or more gases in the inner cylinder 54.

[0029] The signal acquisition and processing module 10 is an integrated module comprising a high-speed acquisition circuit for pA / nA analog current signals, a PMT high-voltage output circuit (0-800V DC), and its signal processing circuit software. It handles high-speed signal acquisition and processing, primarily responsible for the high-speed acquisition, processing, and storage of signals from the photomultiplier tube (PMT) component on the PFPD detector. The resulting technical advantages include: employing high-precision ADC acquisition technology with a 5-10K acquisition rate, it can distinguish and identify the delayed emission spectra of different substances in the time domain within 0-25 milliseconds after the pulsed flame extinguishes. Figure 11 It is a pulsed flame emission spectrum, which uses a high-speed acquisition circuit to accurately capture each delayed emission spectrum within a time range of 0.1-1 milliseconds.

[0030] Specifically, when using this gas composition online monitoring system based on pulse flame photometry: system preparation and gas connection: connect the high-purity hydrogen gas source to the high-purity hydrogen gas inlet 9, connect the clean combustion air gas source to the combustion air gas inlet 8, connect the sample gas pipeline to be tested to the product gas inlet 7, and connect the bypass gas outlet 6 to the safe exhaust gas pipeline. Gas path leak detection and purging: Turn on the gas source and use the leak detection function inside the detection equipment or manually check the sealing of all gas path connections to ensure there is no leakage. Then, use high-purity carrier gas such as nitrogen or the sample gas itself to thoroughly purge the entire sample flow path, especially the path from the product gas inlet 7 to the quartz combustion chamber 23, to remove air and residual contaminants from the pipeline. Airflow setting and ignition: The parameters of the two airflow EFC ​​controllers 5 are set through the control system to provide preset flow rates of air-rich / hydrogen mixture and hydrogen-rich / air mixture to the ignition chamber and main combustion chamber, respectively. Simultaneously, the flow rate of the sample gas is set. After the parameters are set, the ignition program is initiated, energizing and heating the ignition wire 25 to ignite the mixture in the ignition chamber, which in turn ignites the mixture in the main combustion chamber, forming a stable pulse flame. System preheating and stabilization: After successful ignition, the system enters the preheating stage. During this period, the flame continues to burn, and the optical system, electronic system, especially the photomultiplier tube and signal acquisition module, reach thermal and operational stability. The background signal will gradually decrease and tend to stabilize.

[0031] Calibration: After the system stabilizes, introduce a standard gas containing sulfur or phosphorus of known concentration and record the response value output by the signal acquisition and processing module 10, which is usually the peak height or peak area. By measuring the standard gas at different concentrations, establish a standard working curve of sulfur signal and / or phosphorus signal versus concentration.

[0032] Sample measurement: The standard gas is switched to the sample gas to be tested. The sample gas enters through the product gas inlet 7, most of which is discharged through the bypass, and a small portion of the representative quantum flow enters the quartz combustion chamber 23 through the quartz capillary column 24. The sulfur and phosphorus compounds in the chamber burn and emit light in the pulse flame. The characteristic light is filtered by the filter 28 and then converted into a current signal by the photomultiplier tube (29,212).

[0033] Signal Acquisition and Processing: The signal acquisition and processing module 10 acquires the weak pA / nA level current signal output by the photomultiplier tube at a high speed, such as 5-10kHz sampling rate. The software algorithm identifies the characteristic emission time window of sulfur and phosphorus in each flame pulse cycle, which is usually in the delay period after the flame is extinguished. The signal in this time period is integrated or peaked to effectively deduct background interference such as hydrocarbons.

[0034] Results display and output: The processed signal intensity is compared with the pre-established standard curve to calculate the real-time concentration values ​​of total sulfur and / or total phosphorus in the sample gas. The results are displayed on the device screen and output to the upper-level control system or data recording system through analog or digital interfaces.

[0035] Power off: After the measurement is completed, first switch back to inert purge gas to purge the sample flow path to remove residues. Then, turn off the sample gas, hydrogen gas, and finally the air gas in sequence to extinguish the flame. After the system has cooled down, turn off the power to the equipment. Any content not described in detail in this manual is prior art known to those skilled in the art.

[0036] The above embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Although the invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the invention do not depart from the spirit and scope of the invention and should be covered within the scope of the claims of the invention.

Claims

1. A gas composition online monitoring system based on pulsed flame photometry, comprising monitoring equipment (1), characterized in that: The monitoring device (1) is equipped with a PFPD detector (2). A bypass gas outlet (6), a product gas inlet (7), a combustion air inlet (8), and a high-purity hydrogen inlet (9) are fixedly installed at the front end of the monitoring device (1). A signal acquisition and processing module (10) is fixedly connected to one end of the PFPD detector (2). The PFPD detector (2) includes a fixedly installed lower detector body (21) and an upper detector body (22). A quartz combustion chamber (23) is fixedly installed inside the upper body (22). The quartz combustion chamber (23) is equipped with two mutually perpendicular reflectors. Quartz light guide tube one (27) and quartz light guide tube two (210) are respectively installed on opposite sides of the two reflectors on the upper body (22) of the detector. A photomultiplier tube one (29) is fixedly connected to the outer end of the quartz light guide tube one (27). A photomultiplier tube two (212) is connected to the outer end of the quartz light guide tube two (210). A triangular reflecting prism (211) is fixedly installed between (210) and photomultiplier tube II (212). The interior of the quartz combustion chamber (23) is connected from top to bottom to include an ignition chamber, an ignition chamber, and a combustion chamber. An ignition wire (25) is fixedly installed on the ignition chamber. An exhaust pipe (26) is fixedly installed at the top of the ignition chamber. A quartz capillary column (24) is installed at the bottom of the quartz combustion chamber (23). The bottom of the quartz capillary column (24) is connected to a product gas path. The end of the product gas path is connected to the product gas... The gas inlet head (7) is fixedly installed, and the product gas path is fixedly installed with the bypass gas outlet head (6) through a three-way valve in the middle. The side of the quartz combustion chamber (23) is also fixedly connected with the combustion chamber inlet pipe (3) and the ignition chamber inlet pipe (4). The gas path connected by the combustion chamber inlet pipe (3) and the ignition chamber inlet pipe (4) is equipped with a flow EFC ​​controller (5). The flow EFC ​​controller (5) is also connected and fixedly connected with the combustion air inlet head (8) and the high-purity hydrogen inlet head (9).

2. The gas composition online monitoring system based on pulsed flame photometry according to claim 1, characterized in that: The number of airflow EFC ​​controllers (5) is two. The two airflow EFC ​​controllers (5) respectively modulate the airflow of the hydrogen-rich / air mixture inside the combustion chamber intake pipe (3) and the air-rich / hydrogen mixture inside the ignition chamber intake pipe (4), so that the PFPD detector (2) has a highly stable airflow, thereby generating a highly stable pulse flame.

3. The gas composition online monitoring system based on pulsed flame photometry according to claim 1, characterized in that: The interiors of the airflow EFC ​​controller (5), the bypass gas outlet (6), and the product gas inlet (7) are all passivated.

4. The gas composition online monitoring system based on pulsed flame photometry according to claim 1, characterized in that: The first quartz light guide tube (27) and the second quartz light guide tube (210) are equipped with filters (28), and the filters (28) inside the first quartz light guide tube (27) and the second quartz light guide tube (210) are respectively sulfur type filters and phosphorus type filters.

5. The gas composition online monitoring system based on pulsed flame photometry according to claim 1, characterized in that: The airflow EFC ​​controller (5) includes an outer cylinder (51), with two air inlet pipes (52) fixedly connected to the bottom end of the outer cylinder (51). The air inlet pipes (52) are connected to the combustion air inlet head (8) and the high-purity hydrogen inlet head (9). A solenoid valve (53) is fixedly installed inside the air inlet pipe (52). A hollow inner cylinder (54) is rotatably installed inside the outer cylinder (51). A knob (55) is fixedly installed at one end of the inner cylinder (54). An air outlet pipe (56) is fixedly connected to the other end of the inner cylinder (54). Bearings (58) are fixedly installed at both ends of the inner wall of the inner cylinder (54). A fan blade (59) is rotatably connected between the two bearings (58).

6. The gas composition online monitoring system based on pulsed flame photometry according to claim 5, characterized in that: The inner cylinder (54) has four sets of air inlets (57) on its side wall. The four sets of air inlets (57) are an array of hollow patterns with a gradually increasing diameter.

7. The gas composition online monitoring system based on pulsed flame photometry according to claim 5, characterized in that: The fan blade (59) is composed of multiple spiral blades, and the fan blade (59) is driven to rotate by the airflow entering the air intake pipe (52).

8. The gas composition online monitoring system based on pulsed flame photometry according to claim 1, characterized in that: The signal acquisition and processing module (10) is a high-speed acquisition circuit for pA\nA analog current signals, a PMT high-voltage output circuit (0-800V DC) and its signal processing circuit software integration module.

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