Method for measuring content of chloride ions in coal gas

Abstract

The invention discloses a method for determining the content of chloride ions in coal gas, and relates to the technical field of determination of chloride ions in coal gas. The method for measuring the content of the chloride ions in the coal gas comprises the following steps: S1, a sampling link, S2, an analysis stage and S3, a calculation process, in the sampling link S1, two absorption bottles filled with ultrapure water and an empty absorption bottle are sequentially connected in series at a coal gas sampling opening, the absorption bottle is connected with a high-position gas diffusion pipe by virtue of a wet-type gas flow meter, and then gas is introduced at the flow speed of 0.5 L / min; s2, an analysis stage: pouring the absorption liquid in the two absorption bottles into a beaker, heating to boil, maintaining for 30 seconds, and then cooling to normal temperature for later use; the content X1 of chloride ions in the absorption liquid is calculated, and the formula is X1 = (V1-V0) * C * 0.03545 / V * 10 {6} * 35.5. According to the method, accurate sampling is conducted, an absorption bottle is connected in series, the flow speed is controlled, high-purity ultrapure water is matched, the chloride ion absorption efficiency and accuracy are greatly improved, and a foundation is built for follow-up accurate measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of chlorine ion determination in gas, and particularly relates to a method for determining the chlorine ion content in gas. Background Art

[0002] In the fields of industrial production and gas use, the quality control of gas is of great importance. Among them, the chlorine ion content is a key indicator. There are many defects in the traditional gas chlorine ion determination technology. When sampling, simple devices are often used, and the gas flow rate cannot be accurately controlled, which easily causes insufficient absorption or splashing of the absorption liquid. Moreover, the gas is not pretreated, and the impurity interference is serious. In the analysis stage, it mostly relies on manual operation. The heating temperature is controlled by experience, which is difficult to ensure the effect of removing interfering substances. The adjustment of the solution pH value is rough, which affects the titration accuracy. The judgment of the indicator color change is highly subjective and the error is large. In the calculation process, only basic formulas are used, and the factors of variable gas state and measurement error are not comprehensively considered, resulting in a large deviation in the results, which cannot provide accurate guidance for production and is difficult to meet the requirements of modern fine production. Summary of the Invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and provide a method for determining the chlorine ion content in gas, which can solve the problems in the background art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A method for determining the chlorine ion content in gas, including an S1 sampling link, an S2 analysis stage, and an S3 calculation process. In the S1 sampling link, two absorption bottles filled with ultrapure water and an empty absorption bottle are connected in series at the gas sampling port. The absorption bottles are connected to the gas high-level discharge pipe through a wet gas flowmeter, and then gas is introduced at a flow rate of 0.5 L / min.

[0005] In the S2 analysis stage, the absorption liquid in the two absorption bottles is poured into a beaker, heated to boiling and maintained for 30 seconds, and then cooled to room temperature for standby.

[0006] Measure a certain amount of the absorption liquid to be measured and place it in a conical flask. Add phenolphthalein test solution, and adjust the pH value with sodium hydroxide solution and nitric acid solution until the red color of the solution just fades.

[0007] After adding potassium chromate solution, titrate with silver nitrate solution with a concentration of 0.002938 mol / L until the solution just shows a brick-red precipitate, and at the same time carry out a blank test.

[0008] In the S3 calculation process, first calculate the chlorine ion content X1 in the absorption liquid. The formula is X1=(V1 - V0)×C×0.03545 / V×10^{6}×35.5.

[0009] Next, calculate the chloride ion content Cr per cubic meter of gas under standard conditions: Cr = X1 × 0.4 × (273 + t) × 101 × 1000 / (273 × (101 + P - W)), where t represents the gas temperature (°C), P is the difference between the gas pressure and the atmospheric pressure (kPa), and W is the saturated water vapor pressure at t°C (kPa).

[0010] Preferably, during the S1 sampling process, ultrapure water is used as the absorption liquid. Due to its high-purity characteristics, it can avoid introducing additional interfering ions and ensure the accuracy of subsequent measurement results;

[0011] The absorption bottles connected in series can enhance the absorption effect of chloride ions in the gas and reduce the incomplete absorption situation;

[0012] Precisely controlling the gas inlet speed can not only ensure sufficient time for chloride ions to be fully absorbed but also prevent problems such as the splashing of the absorption liquid or incomplete absorption caused by too fast gas flow.

[0013] Preferably, during the S2 analysis stage, heating and boiling can promote the volatilization or chemical reaction of other possible interfering substances in the absorption liquid to remove them. At the same time, it makes the chloride ions more evenly distributed in the solution, which is beneficial for subsequent measurement; The boiling time of 30 seconds has been verified by experiments. It can not only effectively remove interference but also prevent the loss of chloride ions due to long-term heating or the over-concentration of the solution, which may affect the measurement results.

[0014] Preferably, during the S2 analysis stage, after adding potassium chromate solution, titrate with silver nitrate solution with a concentration of 0.002938 mol / L until the solution just shows a brick-red precipitate, and at the same time, conduct a blank test. This step can adjust the solution pH value to a range suitable for the subsequent titration reaction, ensure the accuracy and stability of the chemical reaction during the titration process, and avoid side reactions or affecting the color change effect of the indicator due to inappropriate pH value.

[0015] Preferably, during the S2 analysis stage, silver nitrate reacts with chloride ions to form silver chloride precipitate. Potassium chromate is used as an indicator. When the chloride ions react completely, the excess silver nitrate will react with potassium chromate to form a brick-red precipitate, indicating the end point of the titration; The precise concentration of silver nitrate can ensure the accuracy of the titration result, and the blank test is used to eliminate the influence of other impurity ions or systematic errors that may be introduced during the experiment on the measurement result.

[0016] Preferably, in the S3 calculation process, V1 is the volume (mL) of silver nitrate solution consumed in the titration absorption liquid test, V0 is the volume (mL) of silver nitrate solution consumed in the blank test, V is the volume (mL) of the absorption liquid taken, and C is the concentration (mol / L) of the silver nitrate solution. This formula is derived based on the stoichiometric relationship of chemical reactions. By accurately measuring the volumes of each solution and the known concentration of silver nitrate, the chloride ion content in the absorption liquid can be accurately calculated.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. For the method for determining the chloride ion content in the coal gas, this method samples precisely: Connect the absorption bottles in series and control the flow rate, and cooperate with high-purity ultrapure water, which greatly improves the absorption efficiency and accuracy of chloride ions, avoids interference, and lays a solid foundation for subsequent precise determination. Analyze finely: Operate precisely in each step of heating, adjusting the pH value, and titration, effectively remove interference, stabilize chemical reactions, and accurately indicate the end point. Cooperate with the blank test to greatly reduce errors and ensure the reliability of the measured data. Calculate precisely: Based on the calculation formula according to chemical principles, fully consider the gas state parameters, and achieve precise conversion from the absorption liquid to the coal gas content, providing a strong basis for the regulation of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the drawings and embodiments:

[0020] Figure 1 It is a schematic structural diagram of the equipment used in the present invention.

[0021] Reference numerals: 1. Coal gas pipeline; 2. Sampling pipe; 3. Sampling valve; 4. Empty bottle; 5. Absorption bottle; 6. Wet gas flowmeter; 7. Sampling pump; 8. Return valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] This part will describe the specific embodiments of the present invention in detail. The preferred embodiments of the present invention are shown in the drawings. The role of the drawings is to supplement the description in the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the protection scope of the present invention.

[0023] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc., is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0024] In the description of the present invention, terms such as "greater than", "less than", "exceeding", etc. are understood not to include the number itself, while terms such as "above", "below", "within", etc. are understood to include the number itself. If the first and second are described, it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0025] In the description of the present invention, unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0026] Please refer to Figure 1 , a device corresponding to a method for measuring the chloride ion content in gas, including a gas pipeline 1, a wet gas flowmeter 6 and a sampling pump 7. A sampling pipe 2 is fixedly installed at the sampling end of the gas pipeline 1. The output end of the sampling pipe 2 is fixedly installed with a sampling valve 3. The output end of the sampling valve 3 is connected with two empty bottles 4 and two absorption bottles 5 through a pipeline;

[0027] Among them, a reflux valve 8 is fixedly installed at the reflux end of the gas pipeline 1. The reflux valve 8 is connected with the sampling pump 7 through a pipeline. The sampling pump 7 is connected with the wet gas flowmeter 6 through a pipeline. The empty bottle 4 close to the wet gas flowmeter 6 is connected with the wet gas flowmeter 6 through a pipeline.

[0028] The present invention provides a technical solution: a method for measuring the chloride ion content in gas, including the following method steps: S1 sampling link, S2 analysis stage and S3 calculation process;

[0029] Among them, in the S1 sampling link, two absorption bottles filled with ultrapure water and an empty absorption bottle are connected in series at the gas sampling port. The absorption bottles are connected to the gas high-level relief pipe through a wet gas flowmeter, and then gas is introduced at a flow rate of 0.5 L / min;

[0030] Among them, in this process of the S1 sampling link, ultrapure water is used as the absorption liquid. Due to its high-purity characteristics, it avoids introducing additional interfering ions and ensures the accuracy of subsequent measurement results;

[0031] The absorption bottles connected in series can enhance the absorption effect of chloride ions in the gas and reduce the situation of incomplete absorption;

[0032] Precisely controlling the gas introduction speed can not only ensure sufficient time for chloride ions to be fully absorbed, but also prevent problems such as splashing of the absorption liquid or incomplete absorption caused by too fast gas flow;

[0033] The S2 analysis stage includes pouring the absorption liquid in the two absorption bottles into a beaker, heating to boiling and maintaining for 30 seconds, and then cooling to room temperature for standby;

[0034] Measure a certain amount of the absorption solution to be tested and place it in a conical flask. Add phenolphthalein test solution, and adjust the pH value with sodium hydroxide solution and nitric acid solution until the red color of the solution just fades away;

[0035] After adding potassium chromate solution, titrate with silver nitrate solution with a concentration of 0.002938 mol / L until a brick-red precipitate just appears in the solution, and at the same time carry out a blank test;

[0036] Among them, in the S2 analysis stage, heating and boiling can promote the volatilization or chemical reaction of other possible interfering substances in the absorption solution to be removed, and at the same time make the chloride ions more evenly distributed in the solution, which is conducive to subsequent determination; the boiling time of 30 seconds has been verified by experiments, which can not only effectively remove interference, but also will not cause the loss of chloride ions due to long-term heating or the over-concentration of the solution to affect the measurement results;

[0037] Among them, in the S2 analysis stage, after adding potassium chromate solution, titrate with silver nitrate solution with a concentration of 0.002938 mol / L until a brick-red precipitate just appears in the solution, and at the same time carry out a blank test. This step can adjust the acidity and alkalinity of the solution to a range suitable for subsequent titration reactions, ensure the accuracy and stability of chemical reactions during titration, and avoid side reactions or affecting the color change effect of the indicator due to inappropriate pH value;

[0038] Among them, in the S2 analysis stage, silver nitrate reacts with chloride ions to form silver chloride precipitate. Potassium chromate is used as an indicator. When the chloride ions react completely, the excess silver nitrate will react with potassium chromate to form a brick-red precipitate, indicating the end point of titration; the accurate concentration of silver nitrate can ensure the accuracy of titration results, and the blank test is used to eliminate the influence of other impurity ions or systematic errors that may be introduced during the experiment on the measurement results;

[0039] S3 calculation process, first calculate the chloride ion content X1 in the absorption solution, and the formula is X1=(V1 - V0)×C×0.03545 / V×10^{6}×35.5,

[0040] Among them, V1 is the volume (mL) of silver nitrate solution consumed in the titration of the absorption solution test, V0 is the volume (mL) of silver nitrate solution consumed in the blank test, V is the volume (mL) of the absorption solution taken, and C is the concentration (mol / L) of silver nitrate solution. This formula is obtained based on the stoichiometric relationship of chemical reactions. By accurately measuring the volumes of each solution and the known concentration of silver nitrate, the chloride ion content in the absorption solution can be accurately calculated;

[0041] Next, calculate the chloride ion content Cr per cubic meter of coal gas under standard conditions: Cr = X1 × 0.4 × (273 + t) × 101 × 1000 / (273 × (101 + P - W)), where t represents the temperature of the coal gas (°C), P is the difference between the coal gas pressure and the atmospheric pressure (kPa), and W is the saturated water vapor pressure at t °C (kPa);

[0042] This formula comprehensively considers the influence of gas state parameters on the measurement results, converts the chloride ion content in the absorption liquid to the content in the coal gas, enables the measurement results to accurately reflect the actual situation of the coal gas, and provides a reliable basis for subsequent production process adjustment;

[0043] Furthermore, this method has precise sampling: connecting absorption bottles in series and controlling the flow rate, combined with high-purity ultrapure water, greatly improving the chloride ion absorption efficiency and accuracy, avoiding interference, and laying a solid foundation for subsequent precise measurement. For fine analysis: precise operations are carried out in each step of heating, adjusting the pH value, and titration, effectively removing interference, stabilizing chemical reactions, and precisely indicating the end point. Combined with blank tests, the error is greatly reduced, ensuring the reliability of the measurement data. For precise calculation: based on the calculation formula of chemical principles, fully considering gas state parameters, realizing precise conversion from the absorption liquid to the coal gas content, and providing a strong basis for production process control.

[0044] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art in the said technical field, various changes can be made without departing from the gist of the present invention.

Claims

1. A method for determining the chloride ion content in coal gas, including the sampling step S1, the analysis stage S2 and the calculation process S3, characterized in that: In the S1 sampling step, two absorption bottles filled with ultrapure water and an empty absorption bottle are connected in series at the gas sampling port, and the absorption bottle is connected to the gas high-level release pipe by means of a wet gas flowmeter, and then the gas is introduced at a flow rate of 0.5L / min; In the S2 analysis phase, pour the absorption liquid in the two absorption bottles into a beaker, heat to boiling and maintain for 30 seconds, then cool to room temperature for use; Measure a certain amount of the absorption liquid to be tested and place it in a conical flask, add phenolphthalein test solution, and adjust the pH value with sodium hydroxide solution and nitric acid solution until the red color of the solution just fades away; After adding potassium chromate solution, titrate with silver nitrate solution with a concentration of 0.002938 mol / L until brick-red precipitate appears in the solution, and carry out blank test at the same time; S3 calculation process, first calculate the chloride ion content X1 in the absorption liquid, the formula is X1 = (V1-V0) × C × 0.03545 / V × 10^{6} × 35.5; Then calculate the chloride ion content in each cubic meter of gas under standard conditions: Cr = X1×0.4×(273+t)×101×1000 / (273×(101+PW)), where t represents the gas temperature (℃), P is the difference between the gas pressure and the atmospheric pressure (kPa), and W is the saturated water vapor pressure at t℃ (kPa).

2. The method for determining the chloride ion content in coal gas according to claim 1, wherein: In the S1 sampling process, ultrapure water is used as the absorption liquid. With its high purity characteristics, it avoids the introduction of additional interfering ions and ensures the accuracy of subsequent measurement results. The absorption bottles connected in series can enhance the absorption effect of chloride ions in coal gas and reduce the situation of incomplete absorption; Accurately controlling the gas introduction rate can not only ensure that there is enough time for the chloride ions to be fully absorbed, but also prevent splashing of the absorption liquid or insufficient absorption due to excessively fast airflow.

3. The method for determining the chloride ion content in coal gas according to claim 1, characterized in that: In the S2 analysis stage, heating and boiling can cause other interfering substances that may be present in the absorption liquid to volatilize or undergo chemical reactions to be removed, while making the chloride ions more evenly distributed in the solution, which is beneficial for subsequent measurements; the 30-second boiling time has been experimentally verified to effectively remove interference without affecting the measurement results due to the loss of chloride ions due to volatilization or excessive concentration of the solution caused by long-term heating.

4. The method for determining the chloride ion content in coal gas according to claim 1, wherein: In the S2 analysis stage, after adding potassium chromate solution, the solution is titrated with a silver nitrate solution with a concentration of 0.002938 mol / L until a brick-red precipitate appears in the solution, and a blank test is performed at the same time. This step can adjust the pH of the solution to a range suitable for subsequent titration reactions, ensure the accuracy and stability of the chemical reaction during the titration process, and avoid side reactions or the effect of the indicator color change caused by an inappropriate pH value.

5. A method for determining the chloride ion content in coal gas according to claim 1, characterized in that: In the S2 analysis stage, silver nitrate reacts chemically with chloride ions to generate silver chloride precipitate, and potassium chromate is used as an indicator. When the chloride ions react completely, excess silver nitrate reacts with potassium chromate to generate a brick-red precipitate, indicating the titration endpoint. The precise silver nitrate concentration can ensure the accuracy of the titration result, and the blank test is used to eliminate the influence of other impurity ions or system errors that may be introduced during the experiment on the measurement results.

6. The method for determining the chloride ion content in coal gas according to claim 1, wherein: In the S3 calculation process, V1 is the volume of silver nitrate solution consumed in the titration absorption liquid test (mL), V0 is the volume of silver nitrate solution consumed in the blank test (mL), V is the volume of the taken absorption liquid (mL), and C is the concentration of silver nitrate solution (mol / L). This formula is derived based on the stoichiometric relationship of chemical reactions. By accurately measuring the volumes of each solution and the known concentration of silver nitrate, the chloride ion content in the absorption liquid can be precisely calculated.

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