Chromatographic detection system and detection method for analyzing dissolved gas in transformer oil

Abstract

The invention provides a chromatographic detection system and detection method for analyzing dissolved gas in transformer oil, and the system comprises an integrated solenoid valve type valve terminal module which is used for carrying out flow path switching and controlling a sample to enter an integrated constant flow separation module; the integrated constant-current separation module comprises an input module for a constant-current sample, a first chromatographic column channel for separating a first gas in the sample and a second chromatographic column channel for separating a second gas in the sample; the composite detection module comprises a first catalytic combustion sensor arranged at the outlet of the first chromatographic column channel, and an infrared optical sensor and a second catalytic combustion sensor which are arranged at the outlet of the second chromatographic column channel and are connected in series; and the back-blowing stable base line module is connected with a back-blowing gas circuit controlled by the integrated electromagnetic valve type valve terminal module, and is used for back-blowing the double chromatographic column to remove residual components. On the basis of integration of electromagnetic valve terminal control, double-column parallel separation and multi-sensor detection, the high-standard requirement for online monitoring of the state of power equipment is met.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring and gas chromatography analysis technology, specifically to a chromatographic detection system and method for analyzing dissolved gases in transformer oil. Background Technology

[0002] Power transformers are critical equipment in power grid systems. Early-stage internal faults often manifest as changes in the composition and concentration of dissolved gases in the insulating oil, such as hydrogen, carbon monoxide, carbon dioxide, and various low-carbon hydrocarbons. Therefore, accurate, rapid, and stable chromatographic analysis of dissolved gases in transformer oil is of great significance for ensuring power grid safety. Current technologies, such as traditional gas chromatography systems, often employ single-column separation or a combination of tandem dual-column systems with rotary valve switching, suffer from the following problems: 1. Insufficient separation: A single chromatographic column is difficult to achieve complete separation of H2, CO, CH4 and C2 hydrocarbon gases in a short time. In particular, the separation effect of H2 and CO is not ideal, which affects the accuracy of quantitative analysis.

[0003] 2. Long analysis cycle: The analysis speed of the tandem column system is limited by the slowest eluting component in the entire flow path, which cannot meet the requirements of online monitoring for rapid response.

[0004] 3. Poor baseline stability: Strongly retained components remaining in the chromatographic column elute slowly in subsequent analyses, causing baseline drift and ghost peaks, which affects the identification and quantification of constant components.

[0005] 4. Weak anti-interference ability: Traditional rotary valves have problems such as large dead volume, slow switching speed, easy wear and leakage. Ambient temperature and pressure fluctuations can easily cause the retention time to drift, reducing system stability.

[0006] The search revealed: Chinese invention patent application CN104198601A, entitled "A Parallel Chromatographic Column Analysis Device and Method," includes an injection tube connected to a first injection valve interface V and a second injection valve interface I. Interface II of the first injection valve is connected to the inlet of the first chromatographic column. Interface VI is connected in series with a quantitative tube I and then to interface III. Interface IV is connected to a vent valve, and interface I is connected to the carrier gas. The outlet of the first chromatographic column is connected to a first detector. The second injection valve interface II is connected in series with a quantitative tube II and then to interface V. Interface III is connected to the carrier gas, and interface IV is connected to the inlet of the second chromatographic column. Interface VI is connected to vent valve III. The outlet of the second chromatographic column is connected to interface I of a four-way switching valve. Interface II is connected to vent valve IV, interface III is connected to the carrier gas, and interface IV is connected to the second detector. This technology allows for a single injection of two parallel, separate chromatographic columns without interference, preventing peak broadening caused by multiple detectors connected in series and significantly saving experimental time. However, this technology still has the following technical problems: The three 4-way valves and dual quantitative tubes increase the dead volume space in the gas path, reducing the effective injection volume for the same amount of sample gas, leading to a decrease in peak height and peak area signals. Slight imbalances at the injection tube tip can cause subtle differences in carrier gas flow rates between the two columns. During programmed temperature ramping, these differences can be amplified, potentially causing baseline drift or a "double peak" phenomenon. The application of three 4-way valves, dual quantitative tubes, and dual temperature control increases costs and requires extremely high consistency in dual-column temperature control. For current online oil chromatography monitoring products using two identical detectors, it is necessary to ensure that their response factors, sensitivity, and baseline noise levels are consistent; otherwise, directly comparing the peak areas of the two chromatograms will introduce errors.

[0007] Therefore, there is an urgent need in the field for a dedicated chromatographic detection device that can simultaneously achieve high resolution, rapid analysis, high stability, and strong anti-interference capability. Currently, no descriptions or reports of similar technologies to this invention have been found, nor have similar domestic or international materials been collected. Summary of the Invention

[0008] To address the aforementioned shortcomings in the prior art, this invention provides a chromatographic detection system and method for analyzing dissolved gases in transformer oil.

[0009] According to a first aspect of the present invention, a chromatographic detection system for dissolved gas analysis in transformer oil is provided, comprising: an integrated solenoid valve island module, an integrated constant current separation module, a composite detection module, and a backflush baseline stabilization module; wherein: The integrated electromagnetic valve island module is used for flow path switching to control the entry of the sample and carrier gas into the integrated constant flow separation module; The integrated constant flow separation module includes an input module for constant flow sample connected to the sample inlet of the integrated electromagnetic valve island module and a dual-channel module for separating the sample. The dual-channel module includes a first chromatographic column channel for separating a first type of gas in the sample and a second chromatographic column channel for separating a second type of gas in the sample. The composite detection module includes a first catalytic combustion sensor disposed at the outlet of the first chromatographic column channel and an infrared optical sensor and a second catalytic combustion sensor connected in series disposed at the outlet of the second chromatographic column channel. The backflush baseline stabilization module is connected to the backflush gas path controlled by the integrated solenoid valve island module, and is used to backflush the first chromatographic column channel and the second chromatographic column channel to remove residual components.

[0010] Preferably, the integrated solenoid valve island module includes multiple miniature solenoid valves, which are integrated on a common flow path board. The on / off timing of each miniature solenoid valve is controlled by a programmable logic controller to achieve flow path switching and backflush air path control.

[0011] Preferably, the input module for constant flow samples includes: a flow stabilizing valve, an injection valve, a metering loop, and a front-end output valve, wherein the outlet of the flow stabilizing valve is connected to the inlet of the injection valve, the outlet of the injection valve is connected to the inlet of the metering loop, and the outlet of the metering loop is connected to the inlet of the front-end output valve. The dual-channel module for separating samples includes: a three-way splitter, a first chromatographic column, and a second chromatographic column; one inlet of the three-way splitter is connected to the outlet of the front-end output valve, and the two outlets of the three-way splitter are respectively connected to the first chromatographic column and the second chromatographic column, forming a first chromatographic column channel and a second chromatographic column channel; wherein, the first chromatographic column is a molecular sieve column or a carbon molecular sieve column, specifically used for separating first-type gases in the sample, including: H2, CO, and CH4; the second chromatographic column is a porous polymer packed column, specifically used for separating second-type gases in the sample, including: CO2 and C2 hydrocarbon gases.

[0012] Preferably, the backflushing baseline stabilization module is activated after the target components of the two chromatographic columns have eluted, and backflushes the residue from the outlets of the two chromatographic columns to the outlet of the vent line, respectively.

[0013] Preferably, the backflush baseline stabilization module includes: a backflush switching valve, a constant flow meter, a vent valve, and a vent filter at the constant pressure carrier gas outlet. The outlet of the backflush switching valve is connected to the inlet of the constant flow meter. One outlet of the constant flow meter is connected to the outlet of the first chromatographic column channel of the integrated constant flow separation module, and the other outlet of the constant flow meter is connected to the outlet of the second chromatographic column channel of the integrated constant flow separation module. The inlet of the quantitative loop of the input module is connected to the outlet of the vent valve, and the inlet of the vent valve is connected to the vent filter. The backflush switching valve is used to switch the inflow of carrier gas, the vent valve is used to control the outflow of backflush exhaust gas, and the vent filter is used to prevent foreign matter from the external environment from entering the vent valve.

[0014] Preferably, the first catalytic combustion sensor is used to detect a first gas, including H2, CO and CH4; after the infrared optical sensor is connected in series with the second catalytic combustion sensor, the sample first passes through the infrared sensor to detect CO2 in the second gas, and then enters the second catalytic combustion sensor to detect C2 hydrocarbon gases in the second gas.

[0015] Preferably, the above system further includes: A precision temperature and pressure control module is used to control the temperature and pressure stability of each flow path.

[0016] Preferably, the precision temperature and pressure control module includes: a dual-zone column oven with independent temperature control and an electronic pressure controller; wherein: The dual-zone column oven is used to control the temperature of the integrated constant current separation module and the composite detection module at different operating temperatures, and to independently control the temperature rise of different sections, so that low-boiling-point and high-boiling-point components are eluted in their respective optimal temperature windows. The electronic pressure controller is located at the output end of the constant pressure carrier gas inlet valve and is used to dynamically adjust the pressure in real time to compensate for the effects of temperature changes and column resistance changes, thereby achieving constant pressure mode.

[0017] According to a second aspect of the present invention, a chromatographic detection method using the chromatographic detection system described in any one of the above-described invention is provided, comprising: The sample is simultaneously entered into two chromatographic columns of the integrated constant flow separation module and split into two streams under the control of the integrated solenoid valve island module. The first sample stream, after passing through the first chromatographic column, eluent is detected by the first catalytic combustion sensor; The second sample stream, after passing through the second chromatographic column, was sequentially detected by an infrared optical sensor and a second catalytic combustion sensor. After the column analysis is completed and the corresponding target component elutes, start the backflush gas path to remove the residue from the two columns; The sensor's detection signal is processed to obtain the gas concentration result.

[0018] By adopting the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art: This invention is based on the integration of electromagnetic valve island control, integrated constant current separation and multi-sensor detection, which can effectively solve the shortcomings of existing technologies in terms of separation efficiency, analysis speed, baseline stability and anti-interference ability, and meet the high standard requirements of online monitoring of power equipment status.

[0019] This invention optimizes the separation conditions for gases with different properties by using a dual-column parallel system with dedicated columns, ensuring baseline separation of H2 / CO and C2 hydrocarbon gases and achieving high separation efficiency.

[0020] This invention employs parallel dual-column separation and simultaneous analysis by dual-channel sensors, reducing the total analysis time to less than 10 minutes, significantly improving detection efficiency and providing fast analysis speed.

[0021] This invention employs a precise backflush mechanism controlled by an electromagnetic valve island, which effectively removes residues inside the column, avoids baseline drift, improves data reliability, and provides strong baseline stability.

[0022] This invention utilizes the small dead volume and fast response of the solenoid valve island, combined with precise temperature and pressure control, to effectively suppress the influence of environmental fluctuations; multi-sensor collaborative detection avoids cross-interference and has outstanding anti-interference capabilities.

[0023] This invention utilizes the characteristics of low mechanical wear and long life of the solenoid valve island to achieve high reliability and is suitable for long-term continuous operation.

[0024] This invention effectively improves the accuracy, speed, and reliability of fault gas analysis in power equipment and is applicable to online monitoring and fault early warning systems for transformers. Attached Figure Description

[0025] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of a chromatographic detection system for dissolved gas analysis in transformer oil according to a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the flow path of the electromagnetic valve island in a preferred embodiment of the present invention in the sample injection / analysis state and the backflush state. Among them, (a) is the sample injection / analysis flowchart and (b) is the backflush flowchart.

[0026] Figure 3This is a schematic diagram of the baseline of the dual-column system in a preferred embodiment of the present invention; wherein, (a) is the baseline spectrum of the first column and (b) is the baseline spectrum of the second column, with the baseline fluctuating within 0.2 µV. Detailed Implementation

[0027] The embodiments of the present invention are described in detail below: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0028] Traditional gas chromatography systems often employ single-column separation or a combination of tandem dual columns and rotary valve switching, which suffer from problems such as insufficient resolution, long analysis cycles, poor baseline stability, and weak anti-interference capabilities. Currently, there is a lack of dedicated chromatographic detection devices that can simultaneously achieve high resolution, rapid analysis, high stability, and strong anti-interference capabilities.

[0029] To address the aforementioned problems, one embodiment of the present invention provides a chromatographic detection system for dissolved gas analysis in transformer oil. This system employs high-resolution, interference-resistant chromatographic detection technology, uses an integrated solenoid valve island as the control core, adopts parallel dual-column separation technology, combines catalytic combustion and infrared optical sensors to achieve multi-component detection, and introduces a backflushing mechanism to stabilize the baseline. It has advantages such as high resolution, fast analysis speed, good baseline stability, and strong anti-interference ability, and can meet the high standard requirements of online monitoring of power equipment. It is suitable for dissolved gas analysis in power transformer oil.

[0030] like Figure 1 The diagram shown is a schematic representation of the overall structure of the chromatographic detection system used for dissolved gas analysis in transformer oil in this embodiment. Figure 1 The system comprises: a valve island module integrating the injection valve, vent valve, front-end output valve, inlet valve, backflush switching valve, input valve, output valve, and tail valve; an integrated constant flow module that stably and quantitatively introduces sample gas into the quantitative loop, which, driven by the carrier gas, splits into the dual-column system for component separation; a composite detection module that performs detection on the different components separated by the integrated constant flow separation module through different channels; a backflush baseline stabilization module that backflushes the tubing of the integrated constant flow split module after detection; and a precision temperature and pressure control module that controls the temperature changes in the first and second zones of the dual-zone column oven and monitors the pressure changes in each flow path in real time during the operation of the chromatographic detection system.

[0031] Specifically, such as Figure 2As shown in (a) and (b), the chromatographic detection system for dissolved gas analysis in transformer oil provided in this embodiment may include: an integrated solenoid valve island module, an integrated constant current separation module, a composite detection module, a backflush baseline stabilization module, and a precision temperature and pressure control module; wherein: An integrated solenoid valve-type valve island module is used for flow path switching and to control the entry of the sample and carrier gas into the integrated constant flow separation module; An integrated constant flow separation module includes an input module for constant flow samples connected to the sample inlet of the integrated solenoid valve island module and a dual-channel module for separating samples, wherein the dual-channel module includes a first chromatographic column channel for separating a first type of gas in the sample and a second chromatographic column channel for separating a second type of gas in the sample. The composite detection module includes a first catalytic combustion sensor disposed at the outlet of the first chromatographic column channel and a second catalytic combustion sensor connected in series disposed at the outlet of the second chromatographic column channel. The backflush baseline stabilization module is connected to the backflush gas path controlled by the integrated solenoid valve island module, and is used to backflush the first and second chromatographic column channels to remove residual components.

[0032] In some preferred embodiments, an integrated solenoid valve-type valve island module is used as the control core. It includes multiple miniature solenoid valves, which are integrated on a common flow path board. The on / off timing of each miniature solenoid valve is precisely controlled by a programmable logic controller to achieve flow path switching and backflush air path control.

[0033] In some preferred embodiments, the input module for the constant-flow sample includes: a flow stabilizing valve, an injection valve, a metering loop, and a front-end output valve. The outlet of the flow stabilizing valve is connected to the inlet of the injection valve, the outlet of the injection valve is connected to the inlet of the metering loop, and the outlet of the metering loop is connected to the inlet of the front-end output valve. Flushing and filling the metering loop with a stable and controllable flow rate effectively ensures that the metering loop is fully and completely replaced by the sample, reducing adsorption and residue. A dual-channel module for sample separation includes a three-way splitter, a first chromatographic column, and a second chromatographic column. One inlet of the three-way splitter is connected to the outlet of the front-end output valve, and the two outlets of the three-way splitter are respectively connected to the first and second chromatographic columns, forming a first column channel and a second column channel. The first column is a molecular sieve column or a carbon molecular sieve column, specifically designed for separating first-type gases in the sample, including H2, CO, and CH4. The second column is a porous polymer-packed column, specifically designed for separating second-type gases in the sample, including CO2 and C2 hydrocarbons. This improves separation efficiency, reliability, and flexibility.

[0034] In some preferred embodiments, the backflushing baseline stabilization module is activated after the target components of the two chromatographic columns have eluted, backflushing the residues from the outlets of the two chromatographic columns to the outlet of the vent line, which significantly shortens the analysis cycle, protects the chromatographic columns, and avoids baseline drift.

[0035] In some preferred embodiments, the backflushing baseline stabilization module includes: a backflushing switching valve, a constant flow meter, a vent valve, and a vent filter connected to the constant pressure carrier gas output terminal; the outlet of the backflushing switching valve is connected to the inlet of the constant flow meter, one outlet of the constant flow meter is connected to the outlet of the first chromatographic column channel of the integrated constant flow separation module, the other outlet of the constant flow meter is connected to the outlet of the second chromatographic column channel of the integrated constant flow separation module, the inlet of the quantitative loop of the input module is connected to the outlet of the vent valve, and the inlet of the vent valve is connected to the vent filter. The backflushing switching valve is used to switch the inflow of carrier gas, the vent valve is used to control the outflow of backflushing exhaust gas, and the filter is used to prevent external environmental particles, dust, or small insects from entering the vent valve.

[0036] In some preferred embodiments, a first catalytic combustion sensor is used to detect a first gas, including H2, CO, and CH4. An infrared optical sensor is connected in series with a second catalytic combustion sensor. The sample first passes through the infrared sensor to detect CO2 in the second gas, and then enters the second catalytic combustion sensor to detect C2 hydrocarbons in the second gas. The optical sensor features high accuracy, good selectivity, long lifespan, and is unaffected by oxygen concentration. It does not consume the sample and does not affect the detection of the second catalytic combustion sensor. Furthermore, by connecting and integrating the two sensors into a single system, data fusion and cross-validation can be performed, resulting in a more accurate, reliable, and intelligent gas detection system.

[0037] In some preferred embodiments, the above-described chromatographic detection system may further include: The precision temperature and pressure control module is used to control the temperature and pressure stability of each flow path.

[0038] In some preferred embodiments, the precision temperature and pressure control module includes: a dual-zone column oven with independent temperature control and an electronic pressure controller; wherein: The dual-zone column oven is used for precise temperature control of the integrated constant current separation module and composite detection module at different operating temperatures. Furthermore, the dual-zone column oven allows for optimized independent temperature programs to be set for different zones, ensuring that both low-boiling and high-boiling-point components are eluted within their respective optimal temperature windows. This results in sharper, more symmetrical peaks, improving separation and quantitative accuracy. Low-boiling-point components refer to H2, CO, and CH4 at 40℃~60℃, while high-boiling-point components refer to C2H6, C2H4, C2H2, and CO2 at 150℃~200℃.

[0039] The electronic pressure controller, located at the constant pressure carrier gas output, is used to dynamically adjust the pressure in real time to compensate for the effects of temperature changes and column resistance changes, thus achieving constant pressure mode. It not only provides more precise control but also enables retention time locking and maintains the constant pressure carrier gas required during column backflushing.

[0040] An embodiment of the present invention also provides a chromatographic detection method implemented using the chromatographic detection system provided in the above embodiments of the present invention.

[0041] Specifically, the chromatographic detection method provided in this embodiment may include: The sample is simultaneously entered into two chromatographic columns of the integrated constant flow separation module and split into two streams under the control of the integrated solenoid valve island module. The first sample stream, after passing through the first chromatographic column, eluent is detected by the first catalytic combustion sensor; The second sample stream, after passing through the second chromatographic column, was sequentially detected by an infrared optical sensor and a second catalytic combustion sensor. After the column analysis is completed and the corresponding target component elutes, start the backflush gas path to remove the residue from the two columns; The sensor's detection signal is processed to obtain the gas concentration result.

[0042] In some preferred embodiments: The integrated solenoid valve island module consists of multiple miniature solenoid valves integrated into a common flow path board, enabling programmable control of the flow path. The switching sequence of the solenoid valve island is controlled by an embedded system, achieving automatic operation of sample injection and backflushing.

[0043] The first chromatographic column is used to separate the first gas in the sample, including H2, CO, and CH4; the second chromatographic column is used to separate the second gas in the sample, including CO2, C2H4, C2H6, and C2H2.

[0044] The composite detection module includes a first catalytic combustion sensor, an infrared optical sensor, and a second catalytic combustion sensor. The first catalytic combustion sensor detects a first gas (H2, CO, CH4). The infrared optical sensor is connected in series with the second catalytic combustion sensor. The gas first passes through the infrared sensor to detect CO2 in the second gas, and then enters the second catalytic combustion sensor to detect C2 hydrocarbon gases (C2H4, C2H6, C2H2) in the second gas.

[0045] The backflush baseline stabilization module, controlled by a valve island, is used to backflush the dual chromatographic column to remove residual components. The backflush baseline stabilization module is activated after the target component flows out of the dual chromatographic column, backflushing the residue from the column outlet to the vent line.

[0046] The precision temperature and pressure control module is used to control the temperature and pressure of the chromatographic column and detector, including a dual-zone column oven with independent temperature control and an electronic pressure controller.

[0047] It should be noted that the steps in the method provided by the present invention can be implemented using corresponding modules, devices, units, etc. in the system. Those skilled in the art can refer to the technical solution of the system to implement the steps and flow of the method. That is, the embodiments in the system can be understood as preferred examples of the method, and will not be elaborated here.

[0048] The technical solution provided by the above embodiments of the present invention will be further described in detail below with reference to a verification example.

[0049] In this verification example, the following setup is first performed: 1. Integrated Solenoid Valve Island Module: As the core of the system's fluid control, it consists of multiple miniature solenoid valves integrated on a common flow path board. The on / off sequence of each valve is precisely controlled by a programmable logic controller, enabling rapid and flexible switching of the flow path.

[0050] like Figure 2 As shown in (a) and (b), in the injection state, the sample enters the flow stabilizing valve, and after stabilization, it enters the quantitative loop through the injection valve. The sample uniformity within the quantitative loop is ensured by the front-end output valve, vent valve, and vent filter. In the analysis state, after injection, the quantitative loop collects a quantitative amount of sample. Driven by constant-pressure carrier gas, it passes through the front-end output valve and enters the splitter, then is evenly distributed to the first and second chromatographic columns for separation. The sample separated by the first column enters the first sensor for analysis, while the sample separated by the second column first enters the infrared sensor through the input valve. After analysis, it enters the second sensor through the front-end output valve. After both detections, the sample is output through the tail valve, vent valve, and vent filter. In the backflushing state, after analysis, constant-pressure carrier gas enters from the two outlets of the two columns through the backflushing switching valve and the constant flow device, and then flows back through the splitter to the front-end output valve, quantitative loop, vent valve, and vent filter, carrying away any residual sample from the integrated constant flow separation module.

[0051] 2. Parallel dual-column separation module: includes a first chromatographic column and a second chromatographic column, which are connected in parallel at the valve island outlet; the first chromatographic column is a molecular sieve column or a carbon molecular sieve column, which is specifically used to separate H2, CO, and CH4; the second chromatographic column is a porous polymer packed column, which is specifically used to separate CO2, C2H4, C2H6, and C2H2; 3. Composite detection module: The first catalytic combustion sensor is connected to the outlet of the first chromatographic column and is used to detect H2, CO, and CH4; the infrared optical sensor and the second catalytic combustion sensor are connected in series to the outlet of the second chromatographic column, wherein the infrared sensor is dedicated to detecting CO2, and the second catalytic combustion sensor is used to detect C2H4, C2H6, and C2H2.

[0052] 4. Backflush baseline stabilization module: The backflush gas path is controlled by a solenoid valve island. It is activated after the target component flows out of the dual chromatographic column to backflush the residual component from the column inlet to the vent port to avoid baseline drift.

[0053] 5. Precision temperature and pressure control module: including a dual-zone column oven with independent temperature control and a precision electronic pressure controller, to ensure stable temperature and pressure in each flow path and improve analytical repeatability.

[0054] Furthermore: I. In system configuration: Solenoid valve type valve island: It adopts 10 two-position three-way solenoid valves integrated on the flow path board, and the timing is controlled by MCU.

[0055] Chromatographic columns: The first chromatographic column is a 3m × 1 / 8″ molecular sieve column; the second chromatographic column is a 2m × 1 / 8″ Porapak Q packed column.

[0056] Detectors: Catalytic combustion sensor ×2, NDIR CO2 sensor ×1.

[0057] Temperature and pressure control: Dual-zone column oven, temperature control accuracy ±0.1℃; electronic pressure controller, flow fluctuation <±1%.

[0058] II. Workflow, including: The sample enters the dual-column separation process simultaneously under the control of the solenoid valve island; The effluent from the first chromatographic column was detected by the first catalytic combustion sensor; The elution from the second chromatographic column was sequentially detected by an infrared optical sensor and a second catalytic combustion sensor. After the column analysis is completed and the corresponding target component elutes, backflushing is initiated to remove residues from the dual chromatographic columns. Process the detection signal and output the gas concentration result.

[0059] Furthermore: Sample injection and analysis (0-10 minutes): The electromagnetic valve island controls the synchronous entry of the sample into the dual columns. The effluent from the first column (H2, CO, CH4) is detected by the first catalytic combustion sensor; the effluent from the second column is sequentially passed through the NDIR sensor (for CO2) and the second catalytic combustion sensor (for C2H4, C2H6, and C2H2).

[0060] Backflush to stabilize baseline (10.1 minutes): After the C2H2 peak is finished, the solenoid valve island is switched, and backflush gas is injected from the dual column outlet to purge the residual components to the vent port for 15 minutes.

[0061] System reset: Backflushing complete, valve island reset, ready for the next analysis.

[0062] III. Effect Verification: The standard gas was analyzed using the chromatographic detection system provided by this invention, and the results showed that: H2 and CO separation degree > 1.5, baseline separation of each component; such as Figure 3 As shown in (a) and (b); Total analysis time ≤ 10 minutes; After backflushing, the baseline stabilized rapidly with a drift of <10μV / min; After 30 days of continuous operation, the retention time RSD is less than 0.5%.

[0063] Verification has shown that this invention effectively improves the accuracy, speed, and reliability of fault gas analysis in power equipment, and is suitable for transformer online monitoring and fault early warning systems.

[0064] The chromatographic detection system and method for dissolved gas analysis in transformer oil provided in the above embodiments of the present invention achieve the following technical advantages: 1. High separation: The dual-column parallel configuration optimizes the separation conditions for gases with different properties, ensuring baseline separation of H2 / CO and C2 hydrocarbon gases.

[0065] 2. Fast analysis speed: Parallel dual-column synchronous analysis reduces the total analysis time to less than 10 minutes, significantly improving detection efficiency.

[0066] 3. Strong baseline stability: The precise backflush mechanism controlled by the solenoid valve island effectively removes residues inside the column, avoids baseline drift, and improves data reliability.

[0067] 4. Excellent anti-interference capability: The solenoid valve island has a small dead volume and fast response. Combined with precise temperature and pressure control, it effectively suppresses the influence of environmental fluctuations; multi-sensor collaborative detection avoids cross-interference.

[0068] 5. High system reliability: The solenoid valve island has low mechanical wear, long service life, and is suitable for long-term continuous operation.

[0069] Any matters not covered in the above embodiments of the present invention are well-known in the art.

[0070] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A chromatographic detection system for dissolved gas analysis in transformer oil, characterized in that, include: The system integrates a solenoid valve-type valve island module, an integrated constant current separation module, a composite detection module, and a backflush baseline stabilization module; among which: The integrated electromagnetic valve island module is used for flow path switching to control the entry of the sample and carrier gas into the integrated constant flow separation module; The integrated constant flow separation module includes an input module for constant flow sample connected to the sample inlet of the integrated electromagnetic valve island module and a dual-channel module for separating the sample. The dual-channel module includes a first chromatographic column channel for separating a first type of gas in the sample and a second chromatographic column channel for separating a second type of gas in the sample. The composite detection module includes a first catalytic combustion sensor disposed at the outlet of the first chromatographic column channel and an infrared optical sensor and a second catalytic combustion sensor connected in series disposed at the outlet of the second chromatographic column channel. The backflush baseline stabilization module is connected to the backflush gas path controlled by the integrated solenoid valve island module, and is used to backflush the first chromatographic column channel and the second chromatographic column channel to remove residual components.

2. The chromatographic detection system for dissolved gas analysis in transformer oil according to claim 1, characterized in that, The integrated solenoid valve island module includes multiple miniature solenoid valves, which are integrated on a common flow path board. The on / off timing of each miniature solenoid valve is controlled by a programmable logic controller to achieve flow path switching and backflush air path control.

3. The chromatographic detection system for dissolved gas analysis in transformer oil according to claim 1, characterized in that, The input module for constant flow samples includes: a flow stabilizing valve, an injection valve, a quantitative loop, and a front-end output valve, wherein the outlet of the flow stabilizing valve is connected to the inlet of the injection valve, the outlet of the injection valve is connected to the inlet of the quantitative loop, and the outlet of the quantitative loop is connected to the inlet of the front-end output valve. The dual-channel module for separating samples includes: a three-way splitter, a first chromatographic column, and a second chromatographic column; one inlet of the three-way splitter is connected to the outlet of the front-end output valve, and the two outlets of the three-way splitter are respectively connected to the first chromatographic column and the second chromatographic column, forming a first chromatographic column channel and a second chromatographic column channel; wherein, the first chromatographic column is a molecular sieve column or a carbon molecular sieve column, specifically used for separating first-type gases in the sample, including: H2, CO, and CH4; the second chromatographic column is a porous polymer packed column, specifically used for separating second-type gases in the sample, including: CO2 and C2 hydrocarbon gases.

4. The chromatographic detection system for dissolved gas analysis in transformer oil according to claim 1, characterized in that, The backflush baseline stabilization module is activated after the target components of the two chromatographic columns have eluted, and backflushs the residue from the outlets of the two chromatographic columns to the outlet of the vent line, respectively.

5. The chromatographic detection system for dissolved gas analysis in transformer oil according to claim 4, characterized in that, The backflush baseline stabilization module includes: a backflush switching valve, a constant flow meter, a vent valve, and a vent filter at the constant pressure carrier gas outlet. The outlet of the backflush switching valve is connected to the inlet of the constant flow meter. One outlet of the constant flow meter is connected to the outlet of the first chromatographic column channel of the integrated constant flow separation module, and the other outlet of the constant flow meter is connected to the outlet of the second chromatographic column channel of the integrated constant flow separation module. The outlet of the vent valve is connected to the inlet of the quantitative loop of the input module, and the inlet of the vent valve is connected to the vent filter. The backflush switching valve is used to switch the inlet of the carrier gas, the vent valve is used to control the outlet of the backflush exhaust gas, and the vent filter is used to prevent foreign matter from the external environment from entering the vent valve.

6. The chromatographic detection system for dissolved gas analysis in transformer oil according to claim 1, characterized in that, The first catalytic combustion sensor is used to detect a first gas, including H2, CO and CH4; after the infrared optical sensor is connected in series with the second catalytic combustion sensor, the sample first passes through the infrared sensor to detect CO2 in the second gas, and then enters the second catalytic combustion sensor to detect C2 hydrocarbon gases in the second gas.

7. The chromatographic detection system for dissolved gas analysis in transformer oil according to any one of claims 1-6, characterized in that, Also includes: A precision temperature and pressure control module is used to control the temperature and pressure stability of each flow path.

8. The chromatographic detection system for dissolved gas analysis in transformer oil according to claim 7, characterized in that, The precision temperature and pressure control module includes: a dual-zone column oven with independent temperature control and an electronic pressure controller; wherein: The dual-zone column oven is used to control the temperature of the integrated constant current separation module and the composite detection module at different operating temperatures, and to independently control the temperature rise of different sections, so that low-boiling-point and high-boiling-point components are eluted in their respective optimal temperature windows. The electronic pressure controller is located at the output end of the constant pressure carrier gas inlet valve and is used to dynamically adjust the pressure in real time to compensate for the effects of temperature changes and column resistance changes, thereby achieving constant pressure mode.

9. A chromatographic detection method using the chromatographic detection system according to any one of claims 1-8, characterized in that, include: The sample is simultaneously entered into two chromatographic columns of the integrated constant flow separation module and split into two streams under the control of the integrated solenoid valve island module. The first sample stream, after passing through the first chromatographic column, eluent is detected by the first catalytic combustion sensor; The second sample stream, after passing through the second chromatographic column, was sequentially detected by an infrared optical sensor and a second catalytic combustion sensor. After the column analysis is completed and the corresponding target component elutes, start the backflush gas path to remove the residue from the two columns; The sensor's detection signal is processed to obtain the gas concentration result.

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