A fid-scd tandem detection device

Abstract

The utility model relates to a kind of FID-SCD series detection device, belong to gas-liquid detection field.The device is fixed with hydrogen flame ionization detector and sulfur chemiluminescence detector on the same side by support, is connected by means of stopper and current limiter.The stopper is the "convex" cylinder, metal top plate is provided with central through-hole and air hole, FID nozzle is centrally installed;Current limiter uses the quartz or ceramic insulating tube with inner diameter ≤0.35mm, length 17.5cm±0.1, one end is connected SCD gas inlet, the other end passes through through-hole and FID nozzle maintains 9-10mm interval, outer surface is coated with polytetrafluoroethylene coating.Sample is separated after chromatographic column, FID completes hydrocarbon detection, sulfur combustion product passes through current limiter and enters SCD to realize sulfur content quantitative analysis.The utility model has the advantages that: carbon sulfur data can be obtained simultaneously by one sample, reduce interference, improve analysis efficiency, applicable to petrochemical, environmental monitoring and other fields.

Description

Technical Field

[0001] This utility model relates to gas-liquid detection, specifically to an FID-SCD series detection device. Background Technology

[0002] In various fields such as petroleum refining, natural gas processing, and ambient air monitoring, the analysis and monitoring of hydrocarbon and sulfide content is crucial, not only to ensure product quality specifications but also to comply with relevant environmental regulations. Currently, in these fields, two different detection technologies are typically used to detect hydrocarbon and sulfide content: flame ionization detector (FID) and sulfur chemiluminescence detector (SCD). Currently, FID and SCD are performed using separate instruments, and they do not interfere with each other.

[0003] Limitations of FID (Flame Ionization Detector): While FID responds to almost all petroleum-based carbonaceous organic compounds, making it considered the gold standard for determining total hydrocarbons or hydrocarbons, it lacks a specific response to sulfides, limiting its effectiveness in sulfide detection. Furthermore, the response factors for sulfides on FID differ significantly from those for hydrocarbons, meaning FID cannot be used directly for accurate sulfide quantification. Additionally, the presence of high concentrations of hydrocarbons can completely mask trace amounts of sulfides, making their detection extremely difficult.

[0004] Limitations of SCD (Sulfur Chemiluminescence Detector): While SCDs are ultrasensitive and highly specific for sulfur, exhibiting excellent performance in detecting sulfides, they show little response to non-sulfur compounds, making it difficult to directly use them to test total hydrocarbon content. Furthermore, the presence of high concentrations of hydrocarbons can lead to matrix effects, which may indirectly interfere with the stability and sensitivity of SCDs, thus affecting the accuracy of the detection results. Utility Model Content

[0005] This invention achieves simultaneous detection of hydrocarbons and sulfides by cascading FID and SCD, thereby improving detection efficiency and accuracy. The specific solution is as follows:

[0006] An FID-SCD tandem detection device is disclosed, comprising a flame ionization detector (FID) and a sulfur chemiluminescence detector (SCEM). The FID is equipped with an FID nozzle connected to the column outlet, and the SCEM is equipped with a vacuum pump. The FID and SCEM are mounted on the same side of a support and connected via a limiter and a flow limiter.

[0007] The limiter is a convex cylindrical body with a metal top plate. The metal top plate has a central through hole and several air holes. The FID nozzle is located in the center of the limiter.

[0008] The flow limiter is an insulated tube with an inner diameter of less than 0.35 mm. One end of the flow limiter is connected to the inlet of the sulfur chemiluminescence detector, and the other end passes through the central through hole and is aligned with and close to the FID nozzle.

[0009] Furthermore, the current limiter length is 17.5cm ± 0.1.

[0010] Furthermore, the inlet of the sulfur chemiluminescence detector is provided with an external threaded sleeve, and the outer diameter of the flow limiter is integrally formed with a retaining ring with a diameter not greater than that of the external threaded sleeve. The fastening nut passes through the flow limiter and engages with the external threaded sleeve to fix the flow limiter and the sulfur chemiluminescence detector in place.

[0011] Furthermore, the current limiter is made of quartz or ceramic insulating material.

[0012] Furthermore, the outer surface of the current limiter is coated with a polytetrafluoroethylene coating.

[0013] Furthermore, the other end of the flow restrictor is 9-10mm away from the FID nozzle.

[0014] Furthermore, the inner diameter of the central through hole is 0.5 mm larger than the outer diameter of the current limiter.

[0015] The advantages of this invention are:

[0016] This scheme connects FID and SCD in series, achieving efficient collaborative detection through structural optimization. Its technical advantages are as follows:

[0017] High detection accuracy: FID has a broad response to hydrocarbons, while SCD has high specificity for sulfur. The combination of the two can accurately identify sulfur compounds in complex matrices, avoiding interference from other components, and is especially suitable for the analysis of low-concentration sulfur.

[0018] Improved analytical efficiency: Carbon and sulfur detection data can be obtained simultaneously with a single injection, reducing repeated experiments. This is suitable for scenarios that require simultaneous characterization of compound composition and sulfur content, such as petrochemicals and environmental monitoring.

[0019] Device performance optimization: The design of the limiter and current limiter reduces the outer diameter of the current limiter, eliminating its impact on ignition. At the same time, by centering and aligning the limit point and isolating the intake of external air, interference is reduced, and the performance and stability of the detector are improved.

[0020] Simple connection method: It adopts the original connection method, reducing the complexity of other connection methods of the whole machine, and making it easy to install and maintain. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model, 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 this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of an FID-SCD tandem detection device according to the present invention;

[0023] Figure 2 This is a schematic diagram showing the connection between the current limiter and the "convex" shaped limiter.

[0024] Figure 3 This is a schematic diagram showing the connection between the current limiter and the sulfur chemiluminescence detector. Detailed Implementation

[0025] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with the present invention.

[0026] To fully understand this utility model, detailed steps and structures will be presented in the following description to illustrate the technical solution of this utility model. Preferred embodiments of this utility model are described in detail below; however, in addition to these detailed descriptions, this utility model may have other embodiments.

[0027] The FID-SCD tandem detection device provided by this utility model mainly consists of a hydrogen flame ionization detector 1 and a sulfur chemiluminescence detector 2. For example... Figure 1 As shown, the hydrogen flame ionization detector 1 is equipped with an FID nozzle 11 connected to the column outlet, and the sulfur chemiluminescence detector 2 is equipped with a vacuum pump, the outlet of which is connected to the reaction chamber. Both detectors are fixed to the same side by a bracket. Figure 1 As shown, the hydrogen flame ionization detector 1 and the sulfur chemiluminescence detector 2 are connected by a limiter 3 and a current limiter 4.

[0028] Limiter 3: Adopts a convex cylindrical structure with a metal top plate 31. The plate has a central through hole 32 (inner diameter 0.5mm larger than the outer diameter of the flow limiter 4) and several air holes 33. Simultaneously, when installing limiter 3, it is necessary to ensure that the FID nozzle 11 is centered within limiter 3 (see...). Figure 1 ).

[0029] Flow limiter 4: Made of quartz or ceramic insulating material, with an inner diameter ≤0.35mm and a length of 17.5cm±0.1cm. One end connects to the external threaded sleeve 21 of the inlet of the sulfur chemiluminescence detector 2, and the other end passes through the central through hole 32, maintaining a distance of 9-10mm from the FID nozzle 11 (see...). Figure 3 This distance allows the flow restrictor 4 to only draw in the gas discharged from the combustion of the FID nozzle 11, minimizing the intake of other gases into the limiter 3 and improving detection accuracy.

[0030] In an optional embodiment, the outer surface of the flow limiter 4 is coated with a polytetrafluoroethylene coating to reduce sample adsorption and avoid detection errors.

[0031] The working principle of this utility model is as follows:

[0032] 1) After the sample is separated by the chromatographic column, it is ejected from the FID nozzle 11 and burned in a hydrogen flame to complete the ionization detection of hydrocarbon compounds.

[0033] 2) Some of the sulfur-containing gases in the combustion products are first oxidized into oxygen-containing sulfides in the FID nozzle, and then enter the combustion chamber of the sulfur chemiluminescence detector 2 through the flow limiter 4, where they undergo a reduction reaction with hydrogen and oxygen to generate SO.

[0034] 3) SO enters the reaction tank and undergoes a chemiluminescent reaction with ozone. The light signal is amplified by a photomultiplier tube to achieve quantitative analysis of sulfur content.

[0035] In this invention, the micro-inner diameter (≤0.35mm) of the flow restrictor 4 ensures stable gas flow rate and avoids FID flame disturbance; the 17.5cm length optimizes gas transmission efficiency. The 9-10mm nozzle spacing prevents backflow of outside air and ensures the accuracy of SCD detection.

[0036] The installation steps and requirements of this utility model are as follows:

[0037] S1. The assembly process is as follows:

[0038] S11. Insert the end of the flow restrictor 4 with the retaining ring 41 into the inlet of the sulfur chemiluminescence detector 2, and thread the fastening nut 22 through the flow restrictor 4 to connect it with the external threaded sleeve 21, tightening until sealed (see...). Figure 3 ).

[0039] S12. Pass the other end of the flow restrictor 4 through the central through hole 32 of the limiter 3 to ensure that the distance between the flow restrictor 4 and the FID nozzle 11 is 9-10mm.

[0040] S13. Fix the hydrogen flame ionization detector 1 and the sulfur chemiluminescence detector 2 with the bracket, and adjust the position of the limiter 3 so that the FID nozzle 11 is centered inside the limiter 3 (see...). Figure 1 ).

[0041] S2. Material handling requirements. The operating procedure and parameter control are as follows:

[0042] S21. Power-on preparation.

[0043] S22. Fix the bracket and check the sealing of each component connection.

[0044] S23. Turn on the power and turn on the temperature control system of the hydrogen flame ionization detector 1 and the sulfur chemiluminescence detector 2 to raise the temperature to the set temperature (FID 250-300℃, SCD combustion chamber 700-900℃).

[0045] S24. Ignition and Aging. Once the temperature reaches the set value, turn on the hydrogen and air in the hydrogen flame ionization detector 1 to perform the ignition operation (when ignition is successful, the FID baseline noise is ≥2).

[0046] S25. After ignition and stabilization, turn on the hydrogen, oxygen and carrier gas of sulfur chemiluminescence detector 2, heat to 800℃, and age for 4-6 hours until the baseline drift is ≤2pA / min.

[0047] S3, Sample Analysis.

[0048] S31. After the baseline stabilizes (noise ≤ 0.05 pA, drift ≤ 1 pA / min), inject the sample through the chromatographic injection port.

[0049] S32. Simultaneously record the spectral data of FID (hydrocarbon signal) and SCD (sulfur signal), and perform qualitative and quantitative analysis using workstation software.

[0050] S4. Maintenance and Precautions

[0051] Check the flow limiter 4 for blockage monthly (this can be done by observing and recording changes in vacuum level through flow monitoring). If it is blocked, ultrasonically clean it with 5% hydrofluoric acid solution for 10 minutes, then rinse and dry it with deionized water.

[0052] Depending on the sample, the nozzle should be maintained every 3-6 months. The FID nozzle 11 should be ultrasonically cleaned to avoid carbon buildup affecting the detection sensitivity.

[0053] High-temperature resistant gloves must be worn during operation to prevent contact with high-temperature components (FID nozzle temperature ≥200℃). A combustible gas alarm must be provided at the experimental site. In case of hydrogen leakage, immediately shut off the gas supply and ventilate the area.

[0054] In summary, this invention integrates the advantages of FID and SCD, ensuring gas transmission stability and detection through the cooperation of limiters and flow restrictors, effectively solving the problem of mutual interference between hydrocarbons and sulfides in traditional standalone detection. In practical applications, this device is not only suitable for online monitoring in petroleum refining and natural gas processing, but can also be applied to ambient air detection systems to improve the analytical reliability of complex matrix samples.

[0055] The preferred embodiments of this utility model have been described above. It should be understood that this utility model is not limited to the specific embodiments described above. Devices and structures not described in detail herein should be understood as being implemented in a conventional manner within the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this utility model using the disclosed methods and techniques, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of this utility model. This does not affect the essential content of this utility model. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model, without departing from the content of the technical solution of this utility model, still fall within the protection scope of the technical solution of this utility model.

Claims

1. A tandem FID-SCD detection device, comprising a flame ionization detector (FID) and a sulfur chemiluminescence detector (SCEM), wherein the FID is equipped with an FID nozzle connected to the outlet of a chromatographic column, and the SCEM is equipped with a vacuum pump, characterized in that, The hydrogen flame ionization detector and the sulfur chemiluminescence detector are respectively installed on the same side of the bracket, and are connected by a limiter and a current limiter. The limiter is a "convex" shaped cylinder with a metal top plate. The metal top plate has a central through hole and several air holes. The FID nozzle is located in the center of the limiter. The flow limiter is an insulated tube with an inner diameter of less than 0.35 mm. One end of the flow limiter is connected to the inlet of the sulfur chemiluminescence detector, and the other end passes through the central through hole and is aligned with and close to the FID nozzle.

2. The FID-SCD tandem detection device as described in claim 1, characterized in that, The current limiter is 17.5cm ± 0.

1.

3. The FID-SCD tandem detection device as described in claim 1, characterized in that, The inlet of the sulfur chemiluminescence detector is equipped with an external threaded sleeve. The outer diameter of the flow limiter is integrally formed with a retaining ring whose diameter is no larger than that of the external threaded sleeve. The fastening nut passes through the flow limiter and engages with the external threaded sleeve to fix the flow limiter and the sulfur chemiluminescence detector in place.

4. The FID-SCD tandem detection device as described in claim 1, characterized in that, The current limiter is made of quartz or ceramic insulating material.

5. The FID-SCD tandem detection device as described in claim 1, characterized in that, The outer surface of the current limiter is coated with polytetrafluoroethylene.

6. The FID-SCD tandem detection device as described in claim 1, characterized in that, The other end of the flow restrictor is 9-10mm away from the FID nozzle.

7. The FID-SCD tandem detection device as described in claim 1, characterized in that, The inner diameter of the central through hole is 0.5 mm larger than the outer diameter of the current limiter.

Images