A modular flame photometric detector with sheath gas protection and dual beam correction

Abstract

The application relates to a modular flame photometric detector with sheath gas protection and double-beam correction, belongs to the technical field of analytical chemistry instruments, and comprises a sealed module shell, the inside of the sealed module shell comprises an air path system, a combustion system, an optical detection system and a signal processing system, a detection base is fixedly connected to the inside of the sealed module shell, a cavity is fixedly connected to the top of the detection base, a detector cap is threadedly installed on the top of the sealed module shell, a hydrogen inlet pipe is fixedly connected to the outer wall of the air path system, an air inlet pipe is fixedly connected to the outer wall of the cavity, a sheath gas inlet pipe is fixedly connected to the outer wall of the combustion system, and a circuit interface is installed on the top of the detector cap. The air path system, the combustion system, the optical detection system, the signal processing system and the modular integrated structure are arranged, so that the comprehensive effects of pollution prevention and control, noise suppression and easy-to-use improvement are achieved.

Description

Technical Field

[0001] This application relates to the field of analytical chemistry instrumentation technology, and in particular to a flame photometric detector for gas chromatography. Background Technology

[0002] Currently, flame photometric detectors (FPDs) are specialized detectors for detecting elements such as sulfur and phosphorus, and are widely used in environmental monitoring, petrochemicals, and food safety. Their principle involves the combustion of the analyte in a hydrogen-rich flame, generating a molecular emission spectrum. A quantitative analysis is then performed by detecting the intensity of light at specific wavelengths using an optical system.

[0003] However, existing FPDs suffer from the following long-standing technical challenges: particulate matter (such as carbon black) generated during combustion easily contaminates the optical window (quartz lens), leading to a continuous decrease in light throughput and a deterioration in the signal-to-noise ratio, requiring frequent shutdowns for cleaning and resulting in short maintenance cycles; the fluctuations of the flame itself, changes in airflow, and continuous background radiation introduce significant noise, which is similar in frequency to the signal under test, making it difficult for traditional single-beam hardware filtering methods to effectively distinguish, severely impacting the sensitivity and accuracy of trace detection; traditional FPDs have a loose structure and complex optical path adjustment, making installation, debugging, and maintenance inconvenient for users, hindering rapid field deployment and standardized production.

[0004] Therefore, there is an urgent need for a comprehensive solution that can simultaneously address the issues of pollution, noise, and ease of use in relation to the aforementioned technologies. Utility Model Content

[0005] The purpose of this application is to provide a modular flame photometric detector with sheath gas protection and dual-beam correction, which has the advantages of high stability, high sensitivity, low maintenance and ease of use, and solves the problems of pollution, noise and ease of use.

[0006] This application provides a modular flame photometric detector with sheath gas protection and dual-beam correction, employing the following technical solution: A modular flame photometric detector with sheath gas protection and dual-beam correction includes a sealed module housing. The sealed module housing contains a gas path system, a combustion system, an optical detection system, and a signal processing system. A detection base is fixedly connected inside the sealed module housing. A cavity is fixedly connected to the top of the detection base. A detector cap is threadedly installed on the top of the sealed module housing. A hydrogen inlet pipe is fixedly connected to the outer wall of the gas path system. An air inlet pipe is fixedly connected to the outer wall of the cavity. A sheath gas inlet pipe is fixedly connected to the outer wall of the combustion system. A circuit interface is installed on the top of the detector cap.

[0007] By adopting the above technical solution, the gas path, combustion, optical detection system, signal processing system, and preamplifier circuit are integrated and packaged in a hermetically sealed metal housing. With quick-connect interface and sealed structure, installation is simplified and interference from the external environment to the internal components is avoided.

[0008] Preferably, the gas path system includes a central sample channel fixed inside the cavity, a central nozzle fixedly installed at one end of the central sample channel, and a sheath gas nozzle sleeved on the coaxial position of the central nozzle, forming a central sample channel and an annular sheath gas channel, and the sheath gas channel is connected to an external high-purity inert gas source, wherein the high-purity inert gas is nitrogen.

[0009] By adopting the above technical solution, the central sample channel transports a mixture of the sample to be tested and hydrogen, and the annular sheath gas channel sprays high-purity nitrogen to form a gas curtain, which can prevent particulate matter such as carbon black generated by combustion from diffusing to the optical window, thus reducing optical window contamination at the source.

[0010] Preferably, the combustion system includes a combustion chamber fixed to the top of the cavity, and the combustion chamber is made of metal with a sandwich structure to form a heating chamber. A heating film is provided inside the heating chamber of the combustion chamber, and a temperature sensor is electrically connected to the top of the heating film. A temperature controller is installed on the outer wall of the detector cap, and the temperature sensor and the temperature controller are electrically connected through a circuit.

[0011] By adopting the above technical solution, the temperature controller adjusts the heating film power according to the signal fed back by the temperature sensor, so as to keep the combustion chamber at a constant temperature, avoid the influence of ambient temperature fluctuations and airflow changes on the flame combustion state, and stabilize the intensity of the flame emission spectrum.

[0012] Preferably, the optical detection system includes an observation window tube fixed to the top outer wall of the sealed module housing. A viewing window is fixed to the inner wall of the observation window tube. A beam splitter is installed inside the observation window tube. A first filter is installed at the top opening of the observation window tube. A first photomultiplier tube is installed at the top of the observation window tube. A second filter is installed at the bottom opening of the observation window tube. A second photomultiplier tube is installed at the top of the observation window tube.

[0013] By adopting the above technical solutions, the viewing window, combined with sheath gas protection, reduces pollution; the beam splitter splits the flame light beam; and the two sets of filters and photomultiplier tubes capture the characteristic signal and background signal respectively, providing a hardware foundation for noise correction.

[0014] Preferably, the beam splitter divides the light emitted by the flame into two beams. The first beam passes through the first filter and is received by the first photomultiplier tube to form a measurement signal. The second beam passes through the second filter and is received by the second photomultiplier tube to form a reference signal.

[0015] By adopting the above technical solution, the first filter is a narrowband filter that matches the characteristic wavelengths of sulfur and phosphorus, and the second filter is a filter with a non-characteristic wavelength, so that the reference signal accurately reflects the background noise and flame fluctuation interference.

[0016] Preferably, the signal processing system includes a first microprocessor and a second microprocessor, which are respectively installed at the output terminals of the first photomultiplier tube and the second photomultiplier tube.

[0017] By adopting the above technical solution, the microprocessor is configured to execute the difference subtraction algorithm, subtract the reference signal from the measurement signal in real time, and output the result after difference subtraction as the net feature signal.

[0018] Preferably, the outer wall of the sealing module housing is provided with multiple sets of gas passage interfaces, and the gas passage interfaces are respectively connected to the hydrogen inlet pipe, the air inlet pipe and the sheath gas inlet pipe, and quick-connect fittings are used. The circuit interface is a multi-core aviation plug.

[0019] By adopting the above technical solutions, quick-connect fittings enable rapid insertion and removal and sealing of the air circuit, while multi-core aviation plugs integrate power and signal transmission lines, simplifying user installation and maintenance operations and improving ease of use.

[0020] Preferably, the sealing module housing is a metal housing, and a rubber sealing ring is provided at the connection between the detector cap and the sealing module housing.

[0021] By adopting the above technical solutions, the metal casing has good anti-interference and protection performance, and the rubber sealing ring enhances the sealing performance of the casing, preventing dust and moisture from entering the interior and affecting the operation of the components, while reducing the interference of external airflow on the flame.

[0022] In summary, this application includes at least one of the following beneficial technical effects: This modular flame photometric detector features sheath gas protection and dual-beam correction. Through the coordinated design of a gas path system, combustion system, dual-beam optical detection system, and modular integrated structure, it utilizes high-purity nitrogen to form an annular gas curtain via a sheath gas nozzle, preventing combustion particulate matter from contaminating the optical window and extending maintenance cycles. The constant-temperature combustion chamber prevents condensation formation, protecting the instrument and eliminating signal drift caused by condensate adsorption or desorption, thus improving baseline stability. A beam splitter separates the flame light into a measurement beam and a reference beam, capturing characteristic signals and background interference signals respectively. Dual microprocessors cancel out background noise and flame fluctuations through signal processing, enhancing the sensitivity and accuracy of trace detection. It can precisely eliminate common-mode noise caused by flame fluctuations and particulate scattering, making it particularly suitable for eliminating the "quenching effect" interference in sulfur chemiluminescence and for stable detection of trace phosphorus. It upgrades from "passive filtering" to "active noise identification and cancellation," significantly lowering the detection limit. Simultaneously, the modular design with quick-connect interfaces simplifies installation and commissioning processes, facilitating standardized production and rapid field deployment. Attached Figure Description

[0023] Figure 1 This is an overall diagram of this application; Figure 2 This is a cross-sectional view of this application; Figure 3 This is a schematic diagram of the cavity and combustion chamber of this application; Figure 4 This is a schematic diagram of the connection structure between the combustion chamber and the central sample channel in this application; Figure 5 This is a schematic diagram of the connection structure between the temperature controller and the detector cap in this application.

[0024] In the picture: 1. Sealed module housing; 2. Gas path system; 201. Central sample channel; 202. Central nozzle; 203. Sheath gas nozzle; 3. Combustion system; 301. Combustion chamber; 302. Heating film; 303. Temperature sensor; 304. Temperature controller; 4. Optical detection system; 401. Observation window tube; 402. Viewing window; 403. Beam splitter; 404. First filter; 405. First photomultiplier tube; 406. Second filter; 407. Second photomultiplier tube; 5. Signal processing system; 501. First microprocessor; 502. Second microprocessor; 6. Detection base; 7. Cavity; 8. Detector cap; 9. Hydrogen inlet pipe; 10. Air inlet pipe; 11. Sheath gas inlet pipe; 12. Circuit interface. Detailed Implementation

[0025] The following is in conjunction with the appendix Figure 1 - Appendix Figure 5 This application will be described in further detail below.

[0026] Example 1: A modular flame photometric detector with sheath gas protection and dual-beam correction, referring to... Figure 1 , Figure 2 and Figure 3 The system includes a sealed module housing 1. The interior of the sealed module housing 1 includes a gas path system 2, a combustion system 3, an optical detection system 4, and a signal processing system 5. A detection base 6 is fixedly connected inside the sealed module housing 1. A cavity 7 is fixedly connected to the top of the detection base 6. A detector cap 8 is threadedly installed on the top of the sealed module housing 1. A hydrogen inlet pipe 9 is fixedly connected to the outer wall of the gas path system 2. An air inlet pipe 10 is fixedly connected to the outer wall of the cavity 7. A sheath gas inlet pipe 11 is fixedly connected to the outer wall of the combustion system 3. A circuit interface 12 is installed on the top of the detector cap 8.

[0027] By adopting the above technical solution, the gas path, combustion, sheath gas structure, beam splitter 403, dual filters, dual photomultiplier tubes and preamplifier circuit are integrated and packaged in a hermetically sealed metal housing. With quick-connect interface and sealed structure, installation is simplified and interference from the external environment to the internal components is avoided.

[0028] The sealing module housing 1 is a metal housing. A rubber sealing ring is provided at the connection between the detector cap 8 and the sealing module housing 1. The metal housing has good anti-interference and protection performance, while the rubber sealing ring enhances the housing's sealing performance, preventing dust and moisture from entering the interior and affecting the operation of the components, while also reducing the interference of external airflow on the flame. Example 2: A modular flame photometric detector with sheath gas protection and dual-beam correction, referring to... Figure 4 and Figure 5The gas path system 2 includes a central sample channel 201 fixed inside the cavity 7. A central nozzle 202 is fixedly installed at one end of the central sample channel 201. A sheath gas nozzle 203 is sleeved coaxially with the central nozzle 202, forming a central sample channel 201 and an annular sheath gas channel. The sheath gas channel is connected to an external high-purity inert gas source, and the high-purity inert gas is nitrogen. The central sample channel 201 delivers a mixture of the sample to be tested and hydrogen. The annular sheath gas channel sprays high-purity nitrogen to form a gas curtain, which can prevent particulate matter such as carbon black generated by combustion from diffusing to the optical window, reducing optical window contamination from the source. The combustion system 3 includes a combustion chamber 301 fixed at the top of the cavity 7. The combustion chamber 301 is made of metal, and its wall design... The combustion chamber 301 has a sandwich structure forming a heating chamber. A heating film 302 is installed inside the heating chamber. A temperature sensor 303 is electrically connected to the top of the heating film 302. A temperature controller 304 is installed on the outer wall of the detector cap 8, and the temperature sensor 303 and the temperature controller 304 are electrically connected via a circuit. The temperature controller 304 adjusts the power of the heating film 302 based on the signal fed back from the temperature sensor 303, maintaining a constant temperature in the combustion chamber 301. This avoids the influence of ambient temperature fluctuations and airflow changes on the flame combustion state and stabilizes the intensity of the flame emission spectrum. The optical detection system 4 includes an observation window tube 401 fixed to the top outer wall of the sealed module housing 1. A viewing window 402 is fixed to the inner wall of the observation window tube 401. An internal beam splitter 403 is installed. A first filter 404 is installed at the top opening of the observation window tube 401. A first photomultiplier tube 405 is installed at the top of the observation window tube 401. A second filter 406 is installed at the bottom opening of the observation window tube 401. A second photomultiplier tube 407 is installed at the top of the observation window tube 401. The viewing window 402, in conjunction with sheath gas protection, reduces contamination. The beam splitter 403 splits the flame light beam. The two sets of filters and photomultiplier tubes capture characteristic signals and background signals respectively, providing a hardware basis for noise correction. The beam splitter 403 splits the light emitted by the flame into two beams. The first beam passes through the first filter 404 and is received by the first photomultiplier tube 405 to form a measurement signal. The second beam passes through the second filter 406 and the second photomultiplier tube 407. The light is received by the second photomultiplier tube 407 after the light filter 406, forming a reference signal. The first filter 404 is a narrowband filter that matches the characteristic wavelengths of sulfur and phosphorus, and the second filter 406 is a filter with a non-characteristic wavelength, so that the reference signal accurately reflects the background noise and flame fluctuation interference. The signal processing system 5 includes a first microprocessor 501 and a second microprocessor 502. The first microprocessor 501 and the second microprocessor 502 are respectively installed at the output terminals of the first photomultiplier tube 405 and the second photomultiplier tube 407. The microprocessor is configured to execute a differential subtraction algorithm, subtract the reference signal from the measurement signal in real time, and output the result after subtraction as the net characteristic signal. The outer wall of the sealing module housing 1 is provided with multiple sets of gas path interfaces.Furthermore, the gas inlets are interconnected with hydrogen inlet pipe 9, air inlet pipe 10, and sheath gas inlet pipe 11, respectively, and employ quick-connect fittings. The circuit interface 12 is a multi-core aviation plug. The quick-connect fittings enable rapid insertion and removal and sealing of the gas circuits. The multi-core aviation plug integrates power and signal transmission lines, simplifying user installation and maintenance operations and improving ease of use.

[0029] The implementation principle of this application embodiment is as follows: After the sample to be tested is separated by the gas chromatography column, it enters the central sample channel 201 of the gas path system 2, mixes with the hydrogen introduced by the hydrogen inlet pipe 9, and is ejected from the central nozzle 202. High-purity nitrogen is introduced by the sheath gas inlet pipe 11, and forms an annular gas curtain through the sheath gas nozzle 203, which wraps around the outside of the flame. Secondly, the air inlet pipe 10 supplies combustion air to the combustion chamber 301, so that the hydrogen and sample mixture can form a stable hydrogen-rich flame in the combustion chamber 301. The sulfur and phosphorus elements in the test sample produce characteristic emission spectra when burned. The temperature controller 304 monitors the temperature of the combustion chamber 301 in real time through the temperature sensor 303 and adjusts the heating power of the heating film 302 to keep the combustion chamber 301 at a constant temperature of 100-150℃, preventing water vapor and acid gas from condensing and avoiding flame fluctuations. Finally, the light emitted by the flame passes through the viewing window 402 and enters the observation window tube 401. It is split into two beams by the beam splitter 403. The first beam passes through the first filter 404, is received by the first photomultiplier tube 405 and converted into a measurement electrical signal. The second beam passes through the second filter 406 (a non-characteristic wavelength filter), is received by the second photomultiplier tube 407 and converted into a reference electrical signal. The first microprocessor 501 and the second microprocessor 502 amplify, filter and convert the two signals into analog and digital signals respectively. Then, the interference of background noise and flame fluctuations is canceled by the difference operation. Finally, the accurate quantitative detection signal is output to the chromatography workstation through the circuit interface 12 to complete the detection of sulfur and phosphorus elements.

Claims

1. A modular flame photometric detector with sheath gas protection and dual-beam correction, comprising a sealed module housing (1), characterized in that: The sealed module housing (1) includes a gas path system (2), a combustion system (3), an optical detection system (4), and a signal processing system (5). A detection base (6) is fixedly connected inside the sealed module housing (1). A cavity (7) is fixedly connected to the top of the detection base (6). A detector cap (8) is threadedly installed on the top of the sealed module housing (1). A hydrogen inlet pipe (9) is fixedly connected to the outer wall of the gas path system (2). An air inlet pipe (10) is fixedly connected to the outer wall of the cavity (7). A sheath gas inlet pipe (11) is fixedly connected to the outer wall of the combustion system (3). A circuit interface (12) is installed on the top of the detector cap (8).

2. The modular flame photometric detector with sheath gas protection and dual-beam correction according to claim 1, characterized in that: The gas path system (2) includes a central sample channel (201) fixed inside the cavity (7). A central nozzle (202) is fixedly installed at one end of the central sample channel (201). A sheath gas nozzle (203) is sleeved on the coaxial position of the central nozzle (202), forming a central sample channel (201) and an annular sheath gas channel. The sheath gas channel is connected to an external high-purity inert gas source, and the high-purity inert gas is nitrogen.

3. A modular flame photometric detector with sheath gas protection and dual-beam correction according to claim 1, characterized in that: The combustion system (3) includes a combustion chamber (301) fixed on the top of the cavity (7). The combustion chamber (301) is made of metal and its wall is designed as a sandwich structure to form a heating chamber. A heating film (302) is provided inside the heating chamber of the combustion chamber (301). A temperature sensor (303) is electrically connected to the top of the heating film (302). A temperature controller (304) is installed on the outer wall of the detector cap (8). The temperature sensor (303) and the temperature controller (304) are electrically connected through a circuit.

4. A modular flame photometric detector with sheath gas protection and dual-beam correction according to claim 1, characterized in that: The optical detection system (4) includes an observation window tube (401) fixed to the top outer wall of the sealed module housing (1). A viewing window (402) is fixed to the inner wall of the observation window tube (401). A beam splitter (403) is installed inside the observation window tube (401). A first filter (404) is installed at the top opening of the observation window tube (401). A first photomultiplier tube (405) is installed at the top of the observation window tube (401). A second filter (406) is installed at the bottom opening of the observation window tube (401). A second photomultiplier tube (407) is installed at the top of the observation window tube (401).

5. A modular flame photometric detector with sheath gas protection and dual-beam correction according to claim 4, characterized in that: The beam splitter (403) splits the light emitted by the flame into two beams. The first beam passes through the first filter (404) and is received by the first photomultiplier tube (405) to form a measurement signal. The second beam passes through the second filter (406) and is received by the second photomultiplier tube to form a reference signal.

6. A modular flame photometric detector with sheath gas protection and dual-beam correction according to claim 1, characterized in that: The signal processing system (5) includes a first microprocessor (501) and a second microprocessor (502), which are respectively installed at the output ends of the first photomultiplier tube (405) and the second photomultiplier tube (407).

7. A modular flame photometric detector with sheath gas protection and dual-beam correction according to claim 1, characterized in that: The outer wall of the sealing module housing (1) is provided with multiple gas path interfaces, and the gas path interfaces are respectively connected to the hydrogen inlet pipe (9), the air inlet pipe (10) and the sheath gas inlet pipe (11), and quick-connect fittings are used. The circuit interface (12) is a multi-core aviation plug.

8. A modular flame photometric detector with sheath gas protection and dual-beam correction according to claim 1, characterized in that: The sealing module housing (1) is a metal housing, and a rubber sealing ring is provided at the connection between the detector cap (8) and the sealing module housing (1).

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