Method for determining the combustible gas content in a vapor

Abstract

The application discloses a method for determining the content of combustible gas in steam. The sample is collected by the drainage gas collection method: the gas collection container filled with distilled water is inverted in the sink, steam is introduced to condense, the original water in the bottle is replaced and discharged by using the condensed water, so that the non-condensable combustible gas is collected at the top of the bottle, and the air is isolated by the water seal. Then, the standardized syringe sampling is carried out: after being cleaned and lubricated for multiple times, the airtight syringe is used to pass through the bottle plug and draw a certain amount of gas under the liquid surface, and is quickly sealed to avoid pollution. Finally, the sample is analyzed by the gas chromatograph, and the content of the combustible gas in the steam is quantitatively calculated based on the calibration curve or the correction factor established based on the known concentration standard sample. The application has the advantages of strong anti-interference, standard operation, good sample representativeness and low cost, and is especially suitable for accurate monitoring of low-concentration combustible gas.

Description

Technical Field

[0001] This application relates to the field of industrial gas analysis technology, and in particular to a method for determining the combustible gas content in steam. Background Technology

[0002] In the production process of coal chemical plants, the steam system connects core stages such as gasification, conversion, and synthesis. If even a minor leak occurs in the heat exchange equipment through which the steam flows, combustible gases such as hydrogen, methane, and carbon monoxide from the process side can seep into the steam pipeline network. The accumulation of these combustible gases not only accelerates pipeline corrosion but also poses serious safety hazards such as fire and even explosion. Therefore, accurately measuring the combustible gas content in the steam is a crucial step in ensuring the safe and stable operation of the entire plant.

[0003] Currently, the industry mainly uses laboratory gas chromatography for determination, but its sampling process has significant drawbacks: high-temperature steam is prone to condensation during sampling, leading to sample loss or compositional distortion; the mixing of outside air dilutes the sample, causing the test results to remain consistently low; in addition, the sampling operation lacks standardization, resulting in significant human error. Especially in low-concentration monitoring scenarios at the initial stage of a leak, these problems seriously affect the accuracy and reliability of the test data.

[0004] Therefore, there is an urgent need for a steam and combustible gas sampling and determination method that can accurately sample, effectively isolate interference, and has a standardized operating procedure, in order to improve early warning capabilities and meet the urgent need for accurate diagnosis in safe production. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a method for determining the combustible gas content in steam.

[0006] The embodiments of this application disclose the following technical solutions: This application provides a method for determining the combustible gas content in steam, including: Invert the gas collecting container, which is filled with liquid medium, into an external liquid tank containing the same liquid medium, so that the opening of the gas collecting container is submerged below the liquid surface of the external liquid tank. Insert the outlet end of the conduit into the bottom of the gas collection container, and connect the inlet end of the conduit to the steam sampling port. Open the valve of the steam sampling port to allow steam to enter the bottom of the gas collection container through the conduit. The steam condenses into liquid in the gas collection container. Use the condensate to discharge the liquid medium in the gas collection container, so that the volume of non-condensable combustible gas is stored at the top of the gas collection container. When the liquid medium in the gas collection container is discharged to the preset liquid level, close the sampling valve and remove the gas collection container while keeping it in an inverted position to complete the collection of the combustible gas sample. Using an airtight syringe, extract the combustible gas sample from the gas collection container and repeatedly replace and clean the inner cavity of the syringe to remove air and residual media. Insert the syringe needle through the seal of the gas collection container and into the liquid below the liquid level inside the container to extract a first preset volume of combustible gas sample, and then immediately seal the syringe needle. The extracted combustible gas sample is injected into a gas chromatograph for analysis to obtain the chromatographic peak area corresponding to the combustible gas sample. The content of combustible components in the steam is calculated based on the concentration-peak area calibration curve or correction factor established in advance using a standard sample of combustible gas with known concentration.

[0007] In one possible implementation, the liquid medium includes distilled water, the gas collecting container includes a gas collecting bottle, and the gas collecting container filled with the liquid medium is inverted in an external liquid tank containing the same liquid medium, such that the opening of the gas collecting container is submerged below the liquid surface of the external liquid tank, including: Place the gas collecting bottle, which is filled with distilled water and has no air bubbles, upside down in a water tank containing distilled water, so that the mouth of the gas collecting bottle is submerged below the surface of the water tank.

[0008] In one possible implementation, before repeatedly flushing the syringe's inner cavity to remove air and residual media, the process further includes: The inner wall of the syringe is pre-cleaned by drawing a second preset volume of liquid medium.

[0009] In one possible implementation, the inner cavity of the syringe is repeatedly replaced and cleaned to remove air and residual media from the syringe, including: The syringe cavity should be flushed at least three times to remove air and residual media.

[0010] In one possible implementation, the analytical conditions of the gas chromatograph include: a GDX-102 packed column or an HP-5 capillary column, and an oven temperature of 80°C to 100°C.

[0011] In one possible implementation, the gas chromatograph uses a flame ionization detector or a thermal conductivity detector.

[0012] In one possible implementation, the carrier gas of the gas chromatograph is nitrogen with a purity of not less than 99.999%, and the carrier gas flow rate is 30 mL / min to 40 mL / min.

[0013] In one possible implementation, after opening the valve at the steam sampling port, the following is also included: Keep the valve open for the first period of time to purge any residual air from the conduit and the area near the steam sampling port.

[0014] In one possible implementation, the syringe capacity is adapted to the gas chromatograph, including 10 ml or 20 ml.

[0015] In one possible implementation, the step of injecting the extracted combustible gas sample into a gas chromatograph for analysis is completed within 10 minutes after sampling with a syringe.

[0016] Compared with the prior art, this application has the following advantages: By using a gas collection container filled with liquid medium and inverted and submerged in a liquid tank, the introduced steam naturally condenses into liquid within the container. The original liquid medium is discharged through the condensate, while the non-condensable combustible gas remains at the top of the container. This transforms the condensation effect into an efficient separation and collection method for combustible gas, rather than a cause of sample loss, fundamentally avoiding component distortion due to condensation. The gas collection container opening is always submerged below the liquid surface and is kept in an inverted state when removed. The syringe undergoes multiple replacements and cleanings before sampling to remove internal air and residual medium, and the needle is inserted below the liquid surface during sampling. These multiple steps form a gas path seal to isolate the sample from ambient air, preventing sample dilution caused by air contamination and solving the problem of systematically low measurement results. To address the human error caused by the lack of standardized operating procedures, standardized procedures are specified, including the use of an airtight syringe for multiple replacements and cleanings, and immediate sealing after sampling with the needle inserted below the liquid surface. This reduces the discretionary space for human operation and significantly reduces random errors. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a method for determining the combustible gas content in steam, provided as an embodiment of this application; Figure 2 This is a schematic diagram of a drainage and gas collection device provided in an embodiment of this application. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0020] To facilitate understanding of the technical solutions provided in the embodiments of this application, the technical terms involved in the embodiments of this application will be explained below.

[0021] The flame ionization detector (FID) is a highly sensitive and selective gas chromatographic detector. Its working principle is based on the ionization of organic compounds during combustion in a hydrogen-air flame, generating an ion stream. This ion stream signal is proportional to the mass of the organic compound entering the flame. It exhibits excellent response to most carbon-containing organic compounds (especially hydrocarbons), but shows little or no response to inorganic gases, water, carbon dioxide, etc., making it particularly suitable for the detection of combustible gases such as low-carbon hydrocarbons.

[0022] A thermal conductivity detector (TCD) is a general-purpose gas chromatograph detector that works based on the different thermal conductivities of various gases. The detector contains a heated sensing element (such as a hot wire). When a mixture of carrier gas and sample gas flows through it, the change in thermal conductivity causes a change in the resistance of the hot wire, thus generating an electrical signal. TCDs respond to almost all gases, and are particularly sensitive to gases with significantly different thermal conductivities than commonly used carrier gases (such as nitrogen and argon), making them suitable for the analysis of combustible gases containing hydrogen.

[0023] FID is more suitable for detecting organic combustible gases such as hydrocarbons, with high sensitivity and good selectivity; TCD is a general-purpose detector, especially suitable for detecting inorganic or small molecule combustible gases such as hydrogen.

[0024] To facilitate understanding of the technical solutions provided in the embodiments of this application, the background technology involved in the embodiments of this application will be described below.

[0025] As mentioned earlier, the field generally relies on laboratory gas chromatography for analysis, but its sampling process has significant technical shortcomings. During direct sampling, high-temperature vapor condenses rapidly upon cooling, easily leading to sample loss or distortion of component ratios. Simultaneously, the mixing of ambient air dilutes the sample gas, causing systematically lower measurement results. Furthermore, the lack of standardized operating procedures results in significant random errors introduced by human intervention. These deficiencies are particularly pronounced when monitoring low concentrations of flammable gases for early leak warning, severely impacting the accuracy and reliability of the data.

[0026] To address the aforementioned issues, this application utilizes the volume contraction and displacement force generated by the condensation of steam into water upon entering the low-temperature gas collecting bottle to directly collect non-condensable combustible gases. Simultaneously, the water seal formed during the process forms a physical barrier, effectively preventing the intrusion of condensate and ambient air, thus ensuring sample purity at the source and laying the foundation for high accuracy, especially in low-concentration measurements. Secondly, by standardizing the rigorous cleaning and rinsing procedures for the syringe before sampling, the two key sources of contamination—residual air and moisture—are systematically eliminated, minimizing the uncertainty of human operation and ensuring high reproducibility and reliability of the analytical results. Furthermore, the final dry gas sample obtained after steam condensation matches the optimal analytical conditions of the gas chromatograph, not only improving sample representativeness but also completely avoiding column damage and detector interference that could result from direct injection of high-temperature, wet steam. Finally, the entire technical path of this application embodiment is built entirely on conventional glassware and general-purpose chromatographs, without relying on any expensive special pretreatment equipment or sensors. This makes the method have a very low implementation threshold and excellent adaptability to promotion while ensuring high-precision analysis capabilities, and can be widely applied to the daily testing scenarios of various enterprises.

[0027] It should be noted that the method, system, product, equipment, and medium for determining the combustible content in steam provided in this application can be applied to the field of industrial gas analysis technology. The above are merely examples and do not limit the application areas of the method, system, product, equipment, and medium for determining the combustible content in steam provided in this application. Furthermore, the embodiments of this application may not limit the executing entity for determining the combustible content in steam. For example, the method for determining the combustible content in steam in the embodiments of this application can be applied to data processing equipment such as terminal devices or servers. The terminal device can be an electronic device such as a computer or a personal digital assistant (PDA). The server can be a standalone server, a cloud server, or a cluster server composed of multiple servers.

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] The following embodiment illustrates a method for determining the combustible gas content in steam provided in this application. See also... Figure 1 ,Should Figure 1A flowchart of a method for determining the combustible gas content in steam, provided as an embodiment of this application, is included in the following method: S101. Invert the gas collecting container, which is filled with liquid medium, into an external liquid tank containing the same liquid medium, so that the opening of the gas collecting container is submerged below the liquid surface of the external liquid tank.

[0030] This involves establishing a water seal (or liquid seal) system to create the initial conditions for subsequent drainage and gas collection. In practice, the gas collection container (such as a gas collecting bottle) should first be completely filled with a liquid medium (usually distilled water) and free of air bubbles to remove initial air. Then, it is inverted and placed in a water tank containing the same liquid medium, ensuring the container opening remains below the water level to create a sealed liquid seal environment, preventing external air from entering the container during subsequent operations. This utilizes the incompressibility and sealing properties of liquid (water) to construct an initial space isolated from the atmosphere. The inverted position makes it possible to drain the liquid from the container and accumulate gas in the top space.

[0031] S102. Insert the outlet end of the conduit into the bottom of the gas collection container, and connect the inlet end of the conduit to the steam sampling port.

[0032] Establish a transport path for the vapor sample from the sampling point to the gas collection container. The outlet end of the conduit must extend deep into the bottom of the gas collection container, below the initial liquid level. This ensures that when vapor is introduced, bubbles will rise from the bottom, facilitating initial cooling of the vapor as it passes through the liquid and providing adequate isolation from the liquid medium. Ensure the vapor sample is directly introduced into the liquid environment, utilizing the liquid for initial cooling and isolation, and avoid direct contact between the vapor and any residual air that may be present at the top of the container.

[0033] S103. Open the valve of the steam sampling port so that the steam can be introduced into the bottom of the gas collecting bottle through the conduit. The steam condenses into liquid in the gas collecting container. The liquid medium in the gas collecting container is discharged by the volume displacement effect of the condensed liquid, so that the volume of non-condensable combustible gas is stored at the top of the gas collecting container.

[0034] Slowly open the steam sampling valve to allow steam to flow in continuously and steadily. The high-temperature steam enters the low-temperature gas collecting container and the liquid medium, where it rapidly condenses into water (or condensate). After condensation, the steam volume decreases significantly. Under normal pressure, the volume ratio of gaseous water to liquid water is approximately 1700:1. However, within the sealed gas collecting container, the continuous steam flow and condensation process create a slight positive pressure or a negative pressure generated by condensation contraction, drawing in more steam. This effectively pushes and displaces the original liquid medium (distilled water) from the container, causing it to drain from the inverted bottle opening into an external water tank. Meanwhile, the non-condensable combustible gas components in the steam cannot condense and gradually accumulate at the top of the gas collecting container as the liquid is drained; these components include H2, CH4, and CO.

[0035] This method utilizes the volume change and energy release during the vapor phase change (gas to liquid) process to drive the displacement of the medium within the system, thereby achieving the separation and enrichment of combustible gases and large amounts of water vapor. This method cleverly avoids the introduction of external carrier gases, reducing dilution and contamination.

[0036] S104. When the liquid medium in the gas collection container is discharged to the preset liquid level, close the sampling valve and remove the gas collection bottle while keeping it inverted to complete the collection of the combustible gas sample.

[0037] Observe the discharge of the liquid medium from the gas collection container. The preset liquid level is reached when the liquid is almost completely drained, but a small amount remains at the container opening to form a liquid seal. Immediately close the steam sampling valve to cut off the steam source. While keeping the gas collection container inverted to prevent gas from escaping through the top, carefully remove it from the water tank. The small amount of liquid remaining in the container is used to seal the opening, isolating it from air. Thus, by maintaining the liquid seal, the collected combustible gas sample is kept in a slightly positive pressure or equilibrium state isolated from the outside air when sample collection is complete, preventing back-diffusion of air into the sample and ensuring sample purity.

[0038] S105. Using an airtight syringe, extract the combustible gas sample from the gas collection container and perform multiple replacements and cleaning of the syringe's inner cavity to remove air and residual media from the syringe.

[0039] To reduce injection errors, the syringe needs to be pretreated before formal sampling. First, a small amount of combustible gas can be drawn from the gas collection container and then purged. This process can be repeated several times (e.g., 2-3 times). This operation uses the sample gas to displace the air and any residual liquid medium in the dead volume of the syringe, ensuring that the inner cavity of the syringe is thoroughly rinsed with the sample gas.

[0040] Therefore, by using displacement cleaning, contamination (air) and interference (residual moisture) introduced by the sampling tool itself are eliminated to the greatest extent possible, ensuring the representativeness of the sample entering the chromatograph.

[0041] S106. Pass the syringe needle through the seal of the gas collection container and extend it below the liquid surface inside the container. After extracting a first preset volume of combustible gas sample, seal the syringe needle.

[0042] Insert the rinsed syringe needle through the rubber stopper or other sealing material of the gas collecting bottle, ensuring the needle tip is below the surface of any remaining liquid seal within the container, forming a second liquid seal. Then, slowly pull the syringe plunger to draw the required volume (e.g., 10 mL) of flammable gas sample. After drawing, quickly remove the needle from the bottle and immediately seal the syringe needle with a needle cap or a special sealing material.

[0043] This application employs a dual design of a first liquid seal (maintaining liquid level at the bottle opening + inverted storage) and a second liquid seal (needle insertion below the liquid surface for sampling), constructing an air-isolated system throughout the entire process from sample collection to syringe extraction. The first liquid seal ensures the purity of the sample during static preservation, while the second liquid seal ensures the purity during dynamic extraction. These two seals work together to create a complete air-isolated system from sample collection to sample insertion into the syringe. Without the first liquid seal, the sample could be contaminated during transfer; without the second liquid seal, air could be introduced during extraction. This dual protection mechanism is absent in conventional sampling methods and is particularly crucial for detecting low concentrations of combustible gases. Even a trace amount of air contamination can lead to a systematically lower measurement result, a risk fundamentally eliminated by this application's dual liquid seals.

[0044] Therefore, immersing the needle below the liquid surface during extraction effectively prevents external air from being drawn into the sample through the tiny gap between the needle and the seal due to pressure changes inside the bottle. Immediate sealing is to prevent sample gas leakage or exchange with outside air. S107. Inject the extracted combustible sample into the gas chromatograph for analysis to obtain the chromatographic peak area corresponding to the combustible sample.

[0045] Quickly move the sealed syringe to the injection port of the gas chromatograph. Remove the needle cap, fully insert the needle into the injection port, and inject the entire sample into the chromatograph at a steady and rapid speed. The instrument operates under the preset chromatographic conditions. After the components of the combustible gas to be tested are separated in the chromatographic column, they are detected by the detector (such as FID, TCD) and the signal is output. The chromatographic peak area corresponding to each component is recorded.

[0046] Gas chromatography separates different components by utilizing the difference in their partition coefficients between the stationary and mobile phases. The separated components are converted into electrical signals by a detector, and their peak area or peak height is proportional to the content of the component within a certain range, which is the basis of quantitative analysis.

[0047] S108. Calculate the content of combustible components in the steam based on the concentration-peak area calibration curve or correction factor established in advance using a combustible standard sample of known concentration.

[0048] Before or during sample analysis, a standard gas of known and accurate concentration is required. Its composition must be identical to or similar to the sample to a preset threshold. Analysis is performed under identical chromatographic conditions and injection procedures to obtain the peak area of ​​the standard gas. A calibration curve is plotted with concentration on the x-axis and peak area on the y-axis, or a correction factor for a single concentration point is calculated. Subsequently, the peak areas of each component in the sample are substituted into this calibration curve or calculated using the correction factor to obtain the actual concentration of each component in the vapor sample, such as mg / m³ or ppm.

[0049] Therefore, quantification is performed using the external standard method. Since the chromatographic response value (peak area) is affected by various factors such as instrument status and operating conditions, directly using standard substances to establish a quantitative relationship can correct for these systematic influences, thereby obtaining accurate quantitative results.

[0050] In one possible implementation, the core of establishing a concentration-peak area calibration curve or correction factor for a known concentration of combustible gas standard is to establish a quantitative correspondence between combustible gas concentration and gas chromatographic peak area, providing a benchmark for calculating the concentration of the analyte sample. This process must maintain consistency with the analytical conditions of the analyte sample throughout. Methods for constructing the concentration-peak area calibration curve or correction factor include: First, preliminary preparation is necessary. A standard sample with a known and accurate concentration that perfectly matches the component of the combustible gas to be tested must be selected. Low, medium, and high concentration gradients can be chosen to cover the test range. The purity of the standard sample must meet the detection requirements to avoid interference from impurities. Simultaneously, the gas chromatograph parameters are set according to the patented technical solution. A GDX-102 packed column or an HP-5 capillary column is used, with the column temperature controlled at a constant 80-100℃. A flame ionization detector or a thermal conductivity detector is selected depending on the type of combustible gas. Nitrogen gas with a purity ≥99.999% is used as the carrier gas, and the flow rate is adjusted to 30-40 mL / min. Once the instrument baseline fluctuation is ≤0.05 mV and reaches a stable state, the instrument is put into analytical mode. The sampling instrument must be an airtight syringe consistent with the one used for sampling the test sample. The inner wall is first rinsed multiple times with distilled water, and then rinsed multiple times with the standard sample gas to remove internal air and residual moisture.

[0051] To establish the concentration-peak area calibration curve, at least three standard samples with different concentration gradients must be taken. Following the syringe sampling specifications outlined in the patent, the prescribed volume of standard sample should be accurately extracted, the needle immediately sealed, and the sample uniformly injected into the gas chromatograph injection port within 10 minutes to prevent sample diffusion. Each concentration of standard sample should be injected three times, and the corresponding peak area should be recorded each time. The average of the three measurements should be taken as the final peak area for that concentration to reduce random error. Then, using a linear regression method, the standard sample concentration is plotted on the x-axis, and the corresponding average peak area on the y-axis, to fit the data and obtain the calibration curve equation. Simultaneously, the linear correlation coefficient must be verified to be ≥0.995 to ensure a significant linear correspondence between concentration and peak area.

[0052] If you choose to calculate the correction factor, you can select a standard sample with a known concentration close to that of the sample to be tested, and follow the same sampling and injection procedure. Repeat the injection three times and record the average peak area. The correction factor is obtained by dividing the standard sample concentration by the average peak area. If you need to calculate the relative correction factor, you can introduce a reference substance and divide the product of the standard sample concentration and the reference substance peak area by the product of the reference substance concentration and the standard sample peak area.

[0053] After establishing the calibration curve or correction factor, its effectiveness can be verified. Take an intermediate concentration standard sample that was not involved in the establishment process, and analyze it using the same procedure. Calculate its concentration using the established calibration curve or correction factor. The relative error between the calculated value and the actual concentration of the standard sample should be ≤ ±5%. Otherwise, the standard sample injection or instrument parameter adjustment must be repeated. When chromatograph parameters are adjusted, the column is aged, or the batch of standard samples is changed, the calibration curve must be re-established or the correction factor recalculated to ensure that the accuracy of the quantitative standard is not affected by changes in conditions.

[0054] In one possible implementation, the calculation of the combustible component content in the steam requires using a pre-established concentration-peak area calibration curve or correction factor as a quantitative benchmark. The analytical conditions must be strictly maintained consistent with those in the standard calibration stage throughout the process to ensure the accuracy and reliability of the calculation results. The specific implementation process is as follows: First, the pretreatment and injection of the sample to be tested are completed. Then, the chromatographic peak areas of the sample are obtained. The gas chromatograph is run according to preset parameters, and the chromatographic column (GDX-102 packed column or HP-5 capillary column) is kept at a constant temperature of 80-100℃ to separate the combustible components. After detection by an FID or TCD detector, the chromatographic peak areas corresponding to each combustible component in the sample are recorded by the chromatography workstation.

[0055] If a concentration-peak area calibration curve is used for calculation, the measured peak areas of each component need to be substituted into the linear regression equation obtained by fitting a gradient standard sample beforehand: y = ax + b, where y is the peak area, x is the concentration, a is the slope, and b is the intercept. The concentration x = (yb) / a is then calculated by transforming the equation, yielding the content of the combustible component in the sample. During calculation, it is crucial to ensure that the peak area matches the concentration range of the calibration curve; if it exceeds the range, a new calibration curve needs to be prepared.

[0056] If a correction factor is used for calculation, the correction factor f = standard sample concentration / average peak area of ​​the standard sample, obtained during standard sample calibration, needs to be called. Multiplying the measured peak area of ​​the component in the sample to be tested by the correction factor yields the content of the combustible component: concentration = measured peak area × correction factor. If a relative correction factor is used, the calculation must be completed in conjunction with the relevant parameters of the reference material to ensure accurate proportional relationships.

[0057] Finally, the results are verified and corrected. If the combustible gas being tested is a multi-component mixture, the content of each component must be calculated separately before summing the total combustible gas content. Simultaneously, the linear correlation coefficient of the calibration curve (≥0.995) or the relative error of the standard sample verification (≤±5%) must be compared to confirm that the calculation results do not deviate abnormally. If data anomalies are found, issues with the sample injection operation, instrument stability, or peak area reading must be investigated. The sample analysis and calculation must be repeated to ultimately output the accurate content of combustible components in the vapor.

[0058] See Figure 2 , Figure 2 The schematic diagram of the drainage gas collection device provided in this application embodiment shows that the drainage gas collection device is mainly composed of the following parts connected in sequence: a steam sampling valve (1) serves as the inlet for the steam sample; one end of a glass conduit (2) is connected to the valve, and the other end extends into the bottom of a stoppered gas collection bottle (3); the gas collection bottle is placed upside down in a water tank (4) filled with distilled water. Its working state is such that the distilled water that was originally filled in the gas collection bottle has been discharged into the water tank, while the combustible gas to be tested (5) is collected in the space at the top. The entire device achieves the separation and collection of steam condensation and non-condensable combustible gas through the water seal principle.

[0059] In practical application scenarios, the sample collection, pretreatment, and analysis process provided in this application embodiment includes the following specific steps: Step one involves preparing the water displacement gas collection device and collecting the gas. First, prepare a stoppered gas collecting bottle with a volume of 250 ml or 500 ml, the specific choice depending on the required sampling volume. Also prepare a glass tubing, one end of which is connected to the vapor sampling port, and the other end which extends to the bottom of the gas collecting bottle. Prepare a water tank as well. During operation, fill the gas collecting bottle with distilled water, ensuring there are no air bubbles inside. Then, invert the gas collecting bottle into the water tank filled with distilled water and seal the bottle opening tightly with a rubber stopper with the glass tubing attached. The entire device must be airtight with no leaks.

[0060] When collecting the gas, connect the other end of the glass tubing to the steam sampling port. Slowly open the sampling valve to purge any remaining air from the tubing, a process that takes about 10 seconds. Then, allow steam to continuously flow into the gas collecting bottle. As the steam flows through the cooler tubing and the collecting bottle, it will condense into water, gradually discharging the original distilled water from the bottle. Non-condensable combustible gases such as hydrogen and methane contained in the steam will remain in the collecting bottle. When the distilled water in the collecting bottle is almost completely drained, leaving only a small amount to seal the bottle opening and prevent air from entering, close the sampling valve. Finally, remove the collecting bottle from the water tank, keeping it in an inverted position with the bottle opening facing down throughout the removal process to prevent leakage of the collected combustible gases. This completes the collection of the sample gas.

[0061] Step two involves sampling using a syringe. Before sampling, a well-sealed syringe with a capacity of 10 ml or 20 ml is required, chosen to match the injection requirements of the gas chromatograph. Preparation includes rinsing the inner wall of the syringe twice with a second preset volume of liquid medium (such as distilled water), and then rinsing the syringe three times with combustible gas drawn from the gas collecting bottle. The purpose is to thoroughly remove air and residual moisture from the syringe to avoid contaminating subsequent samples.

[0062] For precise sampling, insert the syringe needle through the rubber stopper of the gas collecting bottle and immerse it below the surface of the small amount of water pre-filled inside the bottle to isolate it from air. Then, slowly draw the combustible gas to the predetermined volume, such as 10 ml, and record the accurate volume drawn. After sampling, immediately seal the syringe needle with the needle cap to prevent gas leakage. To ensure the accuracy of the analytical results, the time interval from sampling to the start of chromatographic analysis should be controlled within 10 minutes to minimize sample loss or changes during transfer.

[0063] Step three is gas chromatography analysis. First, perform instrument calibration by turning on the gas chromatograph and setting the appropriate parameters. For the chromatographic column, a GDX-102 packed column or an HP-5 capillary column suitable for most combustible gas analyses can be used. The column oven temperature should be set between 80 and 100 degrees Celsius and maintained at a constant temperature; this temperature range helps ensure effective separation of different combustible gas components. The detector can be a high-sensitivity flame ionization detector (FID), particularly suitable for analyzing low-carbon hydrocarbons, or a thermal conductivity detector, suitable for analyzing hydrogen-containing gas mixtures, depending on the properties of the analyte. Use nitrogen gas with a purity of at least 99.999%, and control the flow rate at 30 to 40 mL per minute. Once the instrument baseline stabilizes, with fluctuations not exceeding 0.05 mV, the instrument is ready for analysis.

[0064] Next, standard calibration is performed. A standard sample of combustible gas with a known concentration is taken, for example, methane standard gas with a concentration of 1000 mg / m³, and its composition should be consistent with the combustible gas to be tested. Sample and inject into the chromatograph in the same manner as in step two above, and record the chromatographic peak area produced by the standard sample. Using this concentration value and the corresponding peak area, establish a calibration curve between concentration and peak area for quantitative analysis, or directly calculate the correction factor.

[0065] Finally, sample analysis is performed. The combustible gas sample obtained in step two is slowly injected into the gas chromatograph inlet at a uniform rate. The injection process should be smooth to avoid sample diffusion. The chromatographic peak area generated by the sample is recorded. Combined with the calibration curve established using standards or the calculated correction factor, the specific content of various combustible components in the vapor can be quantitatively calculated. The entire method, through standardized sampling and injection operations combined with precise chromatographic analysis, aims to achieve accurate determination of low concentrations of combustible gases in vapor media.

[0066] In summary, this application has the following beneficial effects: First, by employing a water displacement gas collection method, the method cleverly utilizes the volume contraction generated by the condensation of steam to create a slight negative pressure, driving sample collection, and physically isolating the sample with a water seal. This design fundamentally avoids the dilution and contamination of the sample by steam condensate and ambient air, thus significantly improving the accuracy of data when measuring low-concentration gases. Second, the method clearly defines standardized operating procedures for syringe cleaning and rinsing, greatly reducing errors introduced by residual air and moisture in the sampling tools, resulting in better reproducibility and reliability of the analytical results. Third, the sample collected by this method is non-condensable dry gas remaining after steam condensation, whose physical state is closer to the standard gas conditions required for gas chromatography analysis. This not only ensures the representativeness of the sample but also avoids potential damage to precision chromatographic columns and detectors caused by direct injection of high-temperature wet steam. Finally, the entire scheme is built on standard laboratory glassware and a general-purpose gas chromatograph, without relying on expensive and complex online pretreatment systems or dedicated sensors. It is characterized by low cost, ease of setup and maintenance, and is particularly suitable for fixed-point, high-precision, and safe sampling analysis in the routine laboratories of various enterprises.

[0067] At the implementation level, this invention can be implemented in industrial settings through standardization. In the equipment preparation stage, only standard-sized stoppered gas collecting bottles, glass tubing, water tanks, and airtight syringes are required. In the personnel operation stage, trained laboratory technicians are required to strictly follow the sample collection and pretreatment procedures specified in the method at the steam sampling point. In the analysis execution stage, analysis is performed on a general-purpose gas chromatograph equipped with a flame ionization detector or thermal conductivity detector under predetermined chromatographic conditions. Data processing can be efficiently completed directly using chromatography workstation software. In terms of application scenarios, this application can directly serve chemical plants, power plants, heating companies, and other occasions requiring safety and quality monitoring of steam systems. It can serve as an effective supplement to online monitoring instruments and also undertake critical calibration functions.

[0068] This application also provides corresponding equipment and computer storage media for implementing the method for determining the combustible content in steam provided in this application.

[0069] The device includes a memory and a processor. The memory is used to store instructions or code, and the processor is used to execute the instructions or code to enable the device to perform the method for determining the combustible content in steam according to any embodiment of this application.

[0070] The computer storage medium stores code, and when the code is run, the device running the code implements the method for determining the combustible gas content in steam according to any embodiment of this application.

[0071] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0072] It should be understood that in this application, "at least one" refers to one or more items, and "more" refers to two or more items. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one" of a, b, or c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0073] It should be understood that the terms center, longitudinal, transverse, up, down, front, back, left, right, vertical, horizontal, top, bottom, inside, outside, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0074] It should be noted that, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0075] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "include," "comprise," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the statement "includes a…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0076] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the combustible gas content in steam, characterized in that, include: An inverted gas collecting container filled with liquid medium is placed in an external liquid tank containing the same liquid medium, such that the opening of the gas collecting container is submerged below the liquid surface of the external liquid tank. The outlet end of the conduit is inserted into the bottom of the gas collection container, and the inlet end of the conduit is connected to the steam sampling port. Open the valve of the steam sampling port so that the steam can be introduced into the bottom of the gas collection container through the conduit. The steam condenses into liquid in the gas collection container. The liquid medium in the gas collection container is discharged by the volume displacement effect of the condensed liquid, so that the volume of non-condensable combustible gas is stored at the top of the gas collection container. When the liquid medium in the gas collection container is discharged to the preset liquid level, the sampling valve is closed and the gas collection container is kept in an inverted state for removal to complete the collection of combustible gas samples. Using an airtight syringe, a sample of combustible gas is drawn from the gas collection container. The inner cavity of the syringe is then repeatedly replaced and cleaned to remove air and residual media from the syringe. The syringe needle is passed through the seal of the gas collection container and inserted below the liquid surface inside the container. After extracting a first preset volume of combustible gas sample, the syringe needle is sealed. The extracted combustible gas sample is injected into a gas chromatograph for analysis to obtain the chromatographic peak area corresponding to the combustible gas sample. The content of combustible components in the steam is calculated based on the concentration-peak area calibration curve or correction factor established in advance using a standard sample of combustible gas with known concentration.

2. The method according to claim 1, characterized in that, The liquid medium includes distilled water, the gas collecting container includes a gas collecting bottle, and the step of inverting the gas collecting container, which is filled with the liquid medium, into an external liquid tank containing the same liquid medium, such that the opening of the gas collecting container is submerged below the liquid surface of the external liquid tank, includes: Place the gas collecting bottle, which is filled with distilled water and has no air bubbles, upside down in a water tank containing distilled water, so that the mouth of the gas collecting bottle is submerged below the surface of the water tank.

3. The method according to claim 1, characterized in that, Before performing multiple replacement cleanings on the inner cavity of the syringe to remove air and residual media, the procedure further includes: The inner wall of the syringe is pre-cleaned by drawing a second preset volume of the liquid medium.

4. The method according to claim 1, characterized in that, The process of repeatedly replacing and cleaning the inner cavity of the syringe to remove air and residual media includes: The inner cavity of the syringe is purged at least three times to remove air and residual media.

5. The method according to claim 1, characterized in that, The analytical conditions of the gas chromatograph include: the chromatographic column is a GDX-102 packed column or an HP-5 capillary column, and the column oven temperature is 80℃ to 100℃.

6. The method according to claim 1, characterized in that, The detector of the gas chromatograph is a flame ionization detector or a thermal conductivity detector.

7. The method according to claim 6, characterized in that, The carrier gas of the gas chromatograph is nitrogen with a purity of not less than 99.999%, and the carrier gas flow rate is 30 mL / min to 40 mL / min.

8. The method according to claim 1, characterized in that, After opening the valve of the steam sampling port, the method further includes: The valve is kept open for a first period of time to purge any residual air from the conduit and the vicinity of the steam sampling port.

9. The method according to claim 1, characterized in that, The syringe has a capacity adapted to the gas chromatograph, including 10 ml or 20 ml.

10. The method according to claim 1, characterized in that, The step of injecting the extracted combustible gas sample into the gas chromatograph for analysis is completed within 10 minutes after sampling with the syringe.

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