Gas purging and absorbing system for measuring content of hydrogen sulfide and measuring method
Through the gas purging absorption system and automatic potential titration method, the problem of difficult hydrogen sulfide in crude oil and liquid sulfur is solved, and high-precision and high-accuracy hydrogen sulfide content analysis is achieved, simplifying the detection process and reducing human factors Influence.
Patent Information
- Application Number
- CN202310803230.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-03
- Publication Date
- 2025-01-03
AI Technical Summary
The prior art is difficult to accurately determine the content of hydrogen sulfide in crude oil and liquid sulfur, and there are problems such as cumbersome detection process, many reagents used, large influences of human factors, and limitations of the method.
Through the gas purging and absorption system, the hydrogen sulfide in the sample escapes and is absorbed by the absorbent liquid through continuous purging of inert gas. Its content is determined by combining automatic potentiometric titration. Nitrogen or helium is used as the inert gas and lead nitrate is used as the titrator , lead ion selection electrode and double salt bridge saturated calomel electrode were measured.
It improves the measurement precision and accuracy, is simple and fast, reduces interference, and achieves a highly automated hydrogen sulfide content analysis.
Smart Images
Figure CN119246761A_ABST
Abstract
Description
Technical Field
[0001] The present invention is a method for determining the content of hydrogen sulfide gas by using a gas purge absorption system and then using a potentiometric titration method, belonging to the field of chemical industry, and particularly relates to the determination of the content of hydrogen sulfide in substances such as crude oil and liquid sulfur. Background Art
[0002] Hydrogen sulfide is an inorganic compound with a molecular formula of H2S and a molecular weight of 34.076. It is a flammable acidic gas under standard conditions. It is colorless and has a rotten egg smell at low concentrations. It has a sulfur smell at extremely low concentrations and is highly toxic. Its aqueous solution is hydrosulfuric acid, which is weaker in acidity, weaker than carbonic acid, but stronger than boric acid. It is soluble in water and easily soluble in alcohols, petroleum solvents and crude oil. Crude oil is usually a light yellow to black, flowing or semi-flowing, viscous liquid with a strong odor. Hydrogen sulfide in crude oil is produced by the metabolism and degradation of organisms that form oil and gas layers, the oxidation of metal sulfides, the thermochemical decomposition of sulfur-containing organic compounds, and the thermochemical reduction of sulfates. A high content of hydrogen sulfide will not only corrode equipment, but more importantly, it may cause harm to people once it escapes. Therefore, the mass fraction of hydrogen sulfide in crude oil is an important indicator of crude oil quality.
[0003] In addition, by monitoring the hydrogen sulfide content in liquid sulfur, on the one hand, it is possible to timely prevent the liquid sulfur from flowing out and causing harm to on-site personnel due to the high hydrogen sulfide content. On the other hand, the hydrogen sulfide content can be effectively controlled through hydrogen sulfide content analysis, reducing the corrosion of liquid sulfur to equipment and pipelines and extending the service life of equipment and pipelines.
[0004] At present, the detection of hydrogen sulfide is mainly applicable to fuel oil and natural gas. The detection of crude oil in the industry mainly includes iodine titration, gas chromatography, colorimetry, etc. The detection of hydrogen sulfide in liquid sulfur includes iodine titration, Fourier transform infrared spectroscopy, and silver nitrate potentiometric titration. Some of these methods are cumbersome, use many reagents, and are greatly affected by human factors. Some of them have limitations. For example, silver nitrate potentiometric titration uses silver ion selective electrodes or sulfur ion selective electrodes. The silver sulfide solid film used as the sensor is easily converted into silver sulfide and loses its sensing activity. The accuracy and precision are not satisfactory.
[0005] In order to solve the problem of determining the content of hydrogen sulfide in the above substances, a set of equipment and methods for determining the content of hydrogen sulfide in crude oil and liquid sulfur were developed. Summary of the invention
[0006] The purpose of the present invention is to provide a gas purge system and a method for determining the content of hydrogen sulfide, so as to solve the problem that it is difficult to detect the content of hydrogen sulfide in crude oil and liquid sulfur.
[0007] Petroleum is a black, brown or yellow, flowing or semi-flowing viscous liquid. Different crude oils have different temperature sensitivities, and their viscosity decreases as the temperature increases. Liquid sulfur solidifies when the temperature is below 120°C. In order to ensure the fluidity and low viscosity of sulfur, the temperature must be kept between 125°C and 145°C.
[0008] The main technical idea of the present invention is that the present invention controls the substance to be tested at a certain temperature, continuously purges the inert gas to make the hydrogen sulfide in the sample escape and be absorbed by a specific absorption liquid, and then determines its content by automatic potentiometric titration.
[0009] The present invention provides a gas purge absorption system for determining the content of hydrogen sulfide, characterized in that the system comprises a gas source, a gas drying device, a gas generating device, a gas scrubbing device and a gas absorbing device which are connected in sequence; a flow meter and a control valve are provided in the connecting pipeline between the gas source and the gas drying device; the gas generating device is provided with a stirring device inside and a controllable temperature heating and heat preservation device outside.
[0010] Furthermore, the components are connected in sequence through glass conduits and flexible tubes.
[0011] Furthermore, the temperature-controllable heating and heat-insulating device is an oil bath or a water bath.
[0012] Furthermore, the stirring device is a magnetic stirrer or a mechanical stirrer.
[0013] Furthermore, the gas absorption device is provided with an outlet for removing excess inert gas.
[0014] The present invention also provides a method for determining the hydrogen sulfide content using the above system, which is characterized in that the hydrogen sulfide content analysis is carried out by inert gas purging and absorption: the inert gas from the gas source is used to purge the gas drying device, the gas generating device, the gas washing device and the gas absorption device; the gas to be measured from the gas generating device is absorbed by the gas absorption device and then measured by automatic potentiometric titration, thereby calculating the hydrogen sulfide content in the sample.
[0015] Furthermore, after the gas to be measured is completely absorbed, the absorption liquid is transferred into a container together with the washing liquid, and lead nitrate is used as a titrant, a lead ion selective electrode is used as an indicator electrode, and a double salt bridge saturated calomel electrode is used as a reference electrode, and the measurement is performed by automatic potentiometric titration; the volume of the standard solution at the potential jump is recorded as V, and the data is processed by the built-in formula of the automatic potentiometric titrator. The mass fraction of hydrogen sulfide in the substance to be measured is calculated by the following formula: mass fraction of hydrogen sulfide, Where V: volume of standard titration solution lead nitrate consumed, mL; c: concentration of standard titration solution lead nitrate: mol / L; m: mass of substance in the gas generating device, g.
[0016] Furthermore, the inert gas is nitrogen or helium; the flow rate of the inert gas is adjusted to 30 mL / min to 300 ml / min; and the purge time is 10 min to 300 min.
[0017] Furthermore, the desiccant in the gas drying device is ammonium carbonate, calcium chloride, or calcium sulfate.
[0018] Furthermore, the substance in the gas generating device is crude oil or liquid sulfur; the temperature of the gas generating device is controlled between 50°C and 300°C.
[0019] Furthermore, the scrubber contains a phosphoric acid solution or a sodium bicarbonate solution, the concentration of the phosphoric acid solution or the sodium bicarbonate solution is in the range of 0.1 mol / L to 0.5 mol / L, and the volume of the phosphoric acid solution or the sodium bicarbonate solution is in the range of 20 mL to 100 mL.
[0020] The present invention also includes pistons and connecting pipes well known in the art.
[0021] The present invention uses a system to purge the solution after absorption, uses a lead nitrate standard solution as a titrant, a lead ion selective electrode as an indicator electrode, and a double salt bridge saturated calomel electrode as a reference electrode, and uses a potentiometric titration method for determination. The present invention not only has a low degree of interference, a high degree of automation, greatly improves precision and accuracy, but is also simple and fast. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a schematic diagram of the structure of a gas purge absorption system for measuring hydrogen sulfide content according to an embodiment of the present invention.
[0023] In the figure, 1 - gas cylinder; 2 - flow meter; 3 - valve; 4 - drying tube; 5 - oil bath or water bath; 6 - gas generating device; 7 - sample to be tested; 8 - stirring device; 9 - gas washing bottle; 10 - absorption bottle. Implementation
[0024] The present invention is described in detail below with reference to the accompanying drawings and embodiments. Example
[0025] The following examples are used to determine the gas purge absorption system for hydrogen sulfide content. Figure 1 , mainly including gas cylinder 1, flow meter 2, control valve 3, drying tube 4, oil bath or water bath 5, gas generating device 6, sample to be tested 7, stirring device 8, gas washing bottle 9, absorption bottle 10. The above-mentioned related parts are connected in sequence through glass conduits and flexible tubes, and of course also include pistons and other parts well known in the art.
[0026] Determination method of the embodiment: Inert purge gas is exported from the gas cylinder 1 and equipped with a flow meter 2 and a control valve 3 for control, and the gas flow rate is adjusted in the range of 30mL / min~300ml / min. The purge gas can be an inert gas such as nitrogen or helium. Before the purge gas is introduced into the measured gas generator 6, it needs to pass through a drying tube 4 to remove the acidic and alkaline gases and moisture contained in the purge gas. A certain mass of crude oil or liquid sulfur is contained in the gas generator 6. The material of the gas generator 6 is glass or ceramic that does not react with the sample 7 to be tested. The gas generator 6 is equipped with a temperature-controllable heating and heat preservation device, and an oil bath or a water bath 5 can be selected according to the required temperature, and the temperature can be adjusted between 50℃~300℃. The gas generator 6 is equipped with a stirring device 8, which can be a magnetic stirring or a mechanical stirring. There is an outlet at the side end of the gas generator 6 to export the measured gas. After the sample is purged for 10min~300min, the exported gas is purified by the washing bottle 9 and enters the gas absorption bottle 10. The gas absorption bottle 10 has an inlet that can be connected to the gas washing bottle 9. The measured gas enters the gas absorption bottle 10 through the conduit. The gas absorption bottle 10 is made of glass or ceramic that does not react with the absorption liquid. The gas absorption bottle 10 has an outlet to discharge excess inert purge gas. The gas absorption bottle 10 is filled with a certain volume of sodium hydroxide absorption liquid according to the properties of the absorbed gas. After the absorption is completed, the absorption liquid and the washing liquid are quantitatively transferred into a container, and the lead nitrate standard solution is used as a titrant to calculate the hydrogen sulfide content in the crude oil or liquid sulfur by potentiometric titration. Example 1
[0027] This example is an analysis process of the hydrogen sulfide content in crude oil. Fill the drying tube with calcium sulfate, and seal the inlet and outlet of the drying tube with absorbent cotton to prevent the calcium sulfate from escaping. Fill the washing bottle with 40mL of 0.3mol / L phosphoric acid solution, and fill the absorption bottle with 40mL of 0.25mol / L sodium hydroxide solution, and connect the gas line as shown in the figure. Calibrate the flow meter to keep the valve in the nitrogen pipeline in the closed state.
[0028] Weigh 305g (accurate to 1g) of crude oil to be tested and put it into the dried gas generating bottle. Put the gas generating bottle into a water bath at 65℃, connect the nitrogen supply line to the generating bottle, ensure that the purge pipeline is below the liquid surface of the substance to be tested, and open the valve. Adjust the nitrogen flow rate to 150mL / min, ventilate for 30min, remove the absorption bottle containing sulfide, rinse the upper end, adapter, tube and gas inlet and outlet with water, and transfer the absorption liquid and washing liquid to the beaker quantitatively. The control volume is about 70mL, and 0.1006moL / L lead nitrate standard solution is used as the titrant, the lead ion selective electrode is used as the indicator electrode, and the double salt bridge saturated calomel electrode is used as the reference electrode. The determination is carried out by potentiometric titration. The volume of the standard solution at the potential jump is recorded as V=2.22mL. Data processing is carried out by the built-in formula of the automatic potentiometric titrator. The mass fraction of hydrogen sulfide in crude oil is 0.0025%.
[0029] The mass fraction of hydrogen sulfide is calculated according to the following formula: , where V: volume of standard lead nitrate solution consumed, mL; c: concentration of standard lead nitrate solution: mol / L; m: mass of crude oil, g. Example 2
[0030] This example is an analysis process of the hydrogen sulfide content in crude oil. Fill the drying tube with calcium sulfate, and seal the inlet and outlet of the drying tube with absorbent cotton to prevent the calcium sulfate from escaping. Fill the washing bottle with 30mL of 0.3mol / L sodium bicarbonate solution, and fill the absorption bottle with 50mL of 0.2mol / L sodium hydroxide solution, and connect the gas line as shown in the figure. Calibrate the flow meter to keep the valve in the nitrogen pipeline in the closed state.
[0031] Weigh 500g (accurate to 1g) of the crude oil to be tested and put it into the dried gas generating bottle. Put the gas generating bottle into a water bath at 80℃, connect the nitrogen supply line to the generating bottle, ensure that the purge pipeline is below the liquid surface of the substance to be tested, and open the valve. Adjust the nitrogen flow rate to 200mL / min, ventilate for 20min, remove the absorption bottle containing sulfide, rinse the upper end, adapter, tube and gas inlet and outlet with water, and transfer the absorption liquid and washing liquid to the beaker quantitatively. The control volume is about 70mL, and 0.01019moL / L lead nitrate standard solution is used as the titrant, the lead ion selective electrode is used as the indicator electrode, and the double salt bridge saturated calomel electrode is used as the reference electrode. The determination is carried out by potentiometric titration. The volume of the standard solution at the potential jump is recorded as V=5.18mL. Data processing is carried out by the built-in formula of the automatic potentiometric titrator. The mass fraction of hydrogen sulfide in crude oil is 0.00036%.
[0032] The mass fraction of hydrogen sulfide is calculated according to the following formula: , where V: volume of standard lead nitrate solution consumed, mL; c: concentration of standard lead nitrate solution: mol / L; m: mass of crude oil, g. Example 3
[0033] This example is an analysis process of the hydrogen sulfide content in liquid sulfur. The drying tube is filled with ammonium carbonate, and the inlet and outlet of the drying tube are sealed with absorbent cotton to prevent the escape of ammonium carbonate. 40mL of 0.3mol / L phosphoric acid solution is loaded into the gas washing bottle, and 40mL of 0.25mol / L sodium hydroxide solution is loaded into the absorption bottle. The gas line is connected as shown in the figure. The flow meter is calibrated to keep the valve in the nitrogen pipeline in the closed state.
[0034] Weigh 200.0g (accurate to 0.5g) of liquid sulfur to be tested and put it into the dried gas generating bottle. Put the gas generating bottle into an oil bath pot maintained at 140℃, connect the nitrogen supply line to the generating bottle, ensure that the purge pipeline is below the liquid surface of the substance to be measured, and open the valve. Adjust the nitrogen flow rate to 200mL / min, ventilate for 1h, remove the absorption bottle containing sulfide, rinse the upper end, adapter, tube and gas inlet and outlet with water, and transfer the absorption liquid and washing liquid to the beaker quantitatively. The control volume is about 80mL, and 0.1009moL / L lead nitrate standard solution is used as the titrant, the lead ion selective electrode is used as the indicator electrode, and the double salt bridge saturated calomel electrode is used as the reference electrode. The determination is carried out by potentiometric titration. The volume of the standard solution at the potential jump is recorded as V=3.12mL. Data processing is carried out by the built-in formula of the automatic potentiometric titrator. The mass fraction of hydrogen sulfide in liquid sulfur is 0.0054%.
[0035] The hydrogen sulfide content is calculated according to the following formula: Hydrogen sulfide mass fraction , where V: volume of standard lead nitrate solution consumed, mL; c: concentration of standard lead nitrate solution: mol / L; m: mass of liquid sulfur, g. Example 4
[0036] This example is an analysis process of the hydrogen sulfide content in liquid sulfur. The drying tube is filled with ammonium carbonate, and the inlet and outlet of the drying tube are sealed with absorbent cotton to prevent the escape of ammonium carbonate. 40mL of 0.5mol / L phosphoric acid solution is placed in the gas washing bottle, and 30mL of 0.4mol / L sodium hydroxide solution is placed in the absorption bottle. The gas line is connected as shown in the figure. The flow meter is calibrated to keep the valve in the nitrogen pipeline in the closed state.
[0037] Weigh 100.5g (accurate to 0.1g) of liquid sulfur to be tested and put it into the dried gas generating bottle. Put the gas generating bottle into an oil bath pot maintained at 140℃, connect the nitrogen supply line to the generating bottle, ensure that the purge pipeline is below the liquid surface of the substance to be measured, and open the valve. Adjust the nitrogen flow rate to 150mL / min, ventilate for 2h, remove the absorption bottle containing sulfide, rinse the upper end, adapter, tube and gas inlet and outlet with water, and transfer the absorption liquid and washing liquid to the beaker quantitatively. The control volume is about 80mL, and 0.1005moL / L lead nitrate standard solution is used as the titrant, the lead ion selective electrode is used as the indicator electrode, and the double salt bridge saturated calomel electrode is used as the reference electrode. The determination is carried out by potentiometric titration. The volume of the standard solution at the potential jump is recorded as V=3.10mL. Data processing is carried out by the built-in formula of the automatic potentiometric titrator. The mass fraction of hydrogen sulfide in liquid sulfur is 0.011%.
[0038] The hydrogen sulfide content is calculated according to the following formula: Hydrogen sulfide mass fraction , where V: volume of standard lead nitrate solution consumed, mL; c: concentration of standard lead nitrate solution: mol / L; m: mass of liquid sulfur, g.
[0039] Implementation Comparative Example 5: Comparing the results of the embodiment of the present invention with those of the iodine titration method, the results are basically consistent with each other, with a relative deviation of no more than 14.3%. Example 6
[0040] By examining the precision test of the present invention, it is found that the results have good repeatability and the relative deviation of parallel determinations is no more than 14.9%.
Claims
1. A gas purge absorption system for determining hydrogen sulfide content, characterized in that The system comprises a gas source, a gas drying device, a gas generating device, a gas scrubber and a gas absorbing device which are connected in sequence; a flow meter and a control valve are provided in the connecting pipeline between the gas source and the gas drying device; a stirring device is provided inside the gas generating device and a temperature-controllable heating and heat-insulating device is provided outside.
2. The system according to claim 1, characterized in that The components are connected in sequence through glass conduits and flexible tubes.
3. The system according to claim 1, characterized in that The temperature-controllable heating and heat-insulating device is an oil bath or a water bath.
4. The system according to claim 1, characterized in that The stirring device is a magnetic stirrer or a mechanical stirrer.
5. The system according to claim 1, characterized in that The gas absorption device is provided with an outlet for removing excess inert gas.
6. A method for measuring hydrogen sulfide content using the system of claim 1, characterized in that The hydrogen sulfide content is analyzed by inert gas purging and absorption: the inert gas from the gas source is used to purge the gas drying device, gas generating device, gas washing device and gas absorption device. The gas to be tested from the gas generating device is absorbed by the gas absorption device and then measured by automatic potentiometric titration, thereby calculating the hydrogen sulfide content in the sample.
7. The method according to claim 6, characterized in that After the gas to be measured is completely absorbed, the absorption liquid and the washing liquid are transferred into a container together, and the lead nitrate is used as the titrant, the lead ion selective electrode is used as the indicator electrode, and the double salt bridge saturated calomel electrode is used as the reference electrode. The automatic potentiometric titration method is used for determination; the volume of the standard solution at the potential jump is recorded as V, and the data is processed by the built-in formula of the automatic potentiometric titrator. The mass fraction of hydrogen sulfide in the substance to be measured is calculated by the following formula: Hydrogen sulfide mass fraction , where V: volume of standard titration solution lead nitrate consumed, mL; c: concentration of standard titration solution lead nitrate: mol / L; m: mass of substance in the gas generating device, g.
8. The method according to claim 6, characterized in that The inert gas is nitrogen or helium; the flow rate of the inert gas is adjusted to 30 mL / min to 300 ml / min; the purge time is 10 min to 300 min.
9. The method according to claim 6, characterized in that The desiccants in the gas drying device are ammonium carbonate, calcium chloride and calcium sulfate.
10. The method according to claim 6, characterized in that The material in the gas generating device is crude oil or liquid sulfur; the temperature of the gas generating device is controlled between 50℃~300℃.
11. The method according to claim 6, characterized in that There is a phosphoric acid solution or a sodium bicarbonate solution in the scrubbing device, the concentration range of the phosphoric acid solution or the sodium bicarbonate solution is 0.1 mol / L~0.5 mol / L, and the volume range of the phosphoric acid solution or the sodium bicarbonate solution is 20 mL~100 mL.
12. The method according to claim 6, characterized in that The absorption liquid in the gas absorption device is a sodium hydroxide solution, the concentration range of the sodium hydroxide absorption liquid is 0.2 mol / L~0.4 mol / L, and the volume range of the sodium hydroxide absorption liquid is 30 mL~50 mL.
13. The method according to claim 7, characterized in that The volume of the absorption liquid and the washing liquid is controlled to be 50mL~100mL; the concentration of the lead nitrate solution is 0.01mol / L~0.1mol / L.
14. The method according to claim 6, characterized in that The gas generating device and the gas absorbing device are made of glass or ceramic which does not react with the sample to be tested.