A combined device and method for determining the hydrogen sulfide content in crude oil

Abstract

The application discloses a combined device and method for determining the content of hydrogen sulfide in crude oil, which comprises a Meng's washing bottle, a closed sample transfer device and an inert gas purger; the closed sample transfer device comprises a sampling barrel and a hydrogen sulfide absorber, and the sampling barrel is provided with crude oil; when the closed sample transfer is performed, the inner cavity of the Meng's washing bottle is communicated with the lower part of the crude oil liquid surface in the inner cavity of the sampling barrel, and the upper part of the crude oil liquid surface in the inner cavity of the sampling barrel is communicated with the gas inlet end of the hydrogen sulfide absorber; the inert gas purger comprises a high-pressure gas device, and when the inert gas purging is performed, the Meng's washing bottle is communicated with the output end of the high-pressure gas device and the gas inlet end of the hydrogen sulfide absorber. Not only can the harm of hydrogen sulfide gas to the operating and analyzing personnel be avoided, but also the accuracy of the analysis result can be improved.

Description

Technical Field

[0001] This invention belongs to the field of crude oil determination, and relates to a combined device and method for determining the hydrogen sulfide content in crude oil. Background Technology

[0002] Developing a combined sampling and transfer device for analyzing the content of escapable hydrogen sulfide in crude oil can improve the accuracy of hydrogen sulfide analysis, reduce the harm caused by hydrogen sulfide to operators and analysts, and protect the atmospheric environment. During oil extraction and processing, hydrogen sulfide hazards can easily form, causing damage to facilities, affecting the health of operators, and even threatening their lives. Hydrogen sulfide is an irritating and asphyxiating toxic gas; inhalation can lead to hydrogen sulfide poisoning, which can damage the central nervous system, eyes, respiratory tract, and heart. Hydrogen sulfide in crude oil can also corrode pipelines, affecting safe production. Therefore, accurate analysis of hydrogen sulfide content in crude oil, timely provision of accurate analytical data to oil and gas production units, and the implementation of preventative measures to reduce hydrogen sulfide hazards and improve safety in the petroleum industry are of great significance.

[0003] When analyzing crude oil containing volatile hydrogen sulfide, each time the sample container lid is opened, a burst of hydrogen sulfide gas, along with volatilized oil vapor, rushes out of the sampling container, posing a risk to the analytical personnel and affecting the analytical results. Furthermore, the sample cannot be shaken thoroughly during weighing to prevent further escape of hydrogen sulfide gas; only the surface sample is weighed each time, severely impacting the analytical results. The hydrogen sulfide escaping during weighing can also cause serious injury to the operators. Additionally, when purging the weighed sample with inert gas, the pressure is difficult to control, hindering the complete escape of hydrogen sulfide and resulting in poor repeatability of the analytical results. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a combined device and method for determining the hydrogen sulfide content in crude oil, which can not only avoid harm to operators and analysts caused by hydrogen sulfide gas, but also improve the accuracy of analysis results.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A combined apparatus for determining the hydrogen sulfide content in crude oil includes a Mendel washing bottle, a closed sample transfer device, and an inert gas purger.

[0007] The closed sample transfer device includes a sampling bucket and a hydrogen sulfide absorber. The sampling bucket contains crude oil. When the closed sample transfer is performed, the inner cavity of the Meng's wash bottle is connected to the part below the crude oil surface in the inner cavity of the sampling bucket, and the part above the crude oil surface in the inner cavity of the sampling bucket is connected to the air inlet of the hydrogen sulfide absorber.

[0008] The inert gas purger includes a high-pressure gas device. When inert gas purging is performed, the Meng's wash bottle is connected to both the output end of the high-pressure gas device and the inlet end of the hydrogen sulfide absorber.

[0009] Preferably, a through hole is provided at the top of the sampling bucket, the through hole is covered with a latex pad, a needle is provided on the latex pad, the head of the needle penetrates the latex pad and extends into the part above the crude oil surface in the inner cavity of the sampling bucket through the through hole, and the tail of the needle is connected to the air inlet of the hydrogen sulfide absorber.

[0010] Preferably, the inner cavity of the Meng's washing bottle is connected to the bottom 40% of the sampling bucket via a pipe.

[0011] Preferably, the hydrogen sulfide absorber contains a zinc acetate solution.

[0012] Furthermore, the hydrogen sulfide absorber is equipped with a glass plate with multiple through holes, which is located in a zinc acetate solution.

[0013] Preferably, the Meng's washing bottle is connected to the output end of the high-pressure gas device by a pipeline, and a valve is installed on the pipeline.

[0014] Preferably, the output end of the high-pressure gas device is connected to multiple Meng's wash bottles.

[0015] Preferably, the high-pressure gas device stores nitrogen gas.

[0016] A method for determining the hydrogen sulfide content in crude oil based on any one of the above-described combined devices, comprising the following steps:

[0017] First, a closed-loop sample transfer is performed. The hydrogen sulfide gas inside the sampling barrel enters the hydrogen sulfide absorber and undergoes a chemical reaction to generate zinc sulfide precipitate. The mass of hydrogen sulfide in the sampling barrel is calculated based on the amount of zinc sulfide precipitate. Then, a certain mass of crude oil in the sampling barrel is weighed and flows into a Mondl wash bottle.

[0018] Then, inert gas is purged. Inert gas is introduced into the Mendel wash bottle. The hydrogen sulfide gas generated in the Mendel wash bottle enters the hydrogen sulfide absorber and undergoes a chemical reaction to generate zinc sulfide precipitate. The mass of hydrogen sulfide in the Mendel wash bottle is calculated based on the amount of zinc sulfide precipitate.

[0019] The mass concentration of hydrogen sulfide in the sampling bucket, X1, is calculated as {M1 / } * 1000000;

[0020] Where M1: the mass of hydrogen sulfide in the sampling bucket, in g; Mtotal: the total mass of the sample and the empty bucket, in g; Mempty: the mass of the empty bucket, in g;

[0021] The mass concentration of hydrogen sulfide in the Meng's wash bottle X2 = {M2 / MMeng} * 1000000;

[0022] Where M2: Mass of hydrogen sulfide in the Menthol wash bottle, in g; MMenthol: Mass of the sample weighed into the Menthol wash bottle;

[0023] The final total mass concentration of hydrogen sulfide, Xtotal, is equal to X1 + X2.

[0024] Preferably, the process for calculating the mass of hydrogen sulfide in the sampling bucket or Mendel's wash bottle is as follows: Add 10 mL of iodine solution with a concentration of 5 g / L and 10 mL of hydrochloric acid solution with a mass ratio of 1:11 to the hydrogen sulfide absorber, mix well, and titrate with sodium thiosulfate solution. Near the endpoint, add 1-2 mL of starch indicator and titrate until the blue color disappears. Calculate the mass of hydrogen sulfide in the sampling bucket or Mendel's wash bottle.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention uses a hydrogen sulfide absorber to absorb hydrogen sulfide that may escape during sample transport, and also ensures a completely sealed, contactless sample transfer process when weighing samples with a balance. An inert gas purger provides stable pressure and inert gas to ensure that hydrogen sulfide in the sample can completely escape. This not only avoids harm to the operators and analysts caused by hydrogen sulfide gas, but also improves the accuracy of the analytical results.

[0027] Furthermore, the needle penetrates the latex pad and extends through the through hole into the portion of the sampling bucket above the crude oil surface. The tail of the needle is connected to the input end of the hydrogen sulfide absorber, ensuring that the hydrogen sulfide gas above the crude oil surface can be fully extracted. When inert gas purging is performed and the sampling bucket is not needed, the needle can be pulled out directly, and the latex pad seals the through hole to ensure that hydrogen sulfide gas does not leak.

[0028] Furthermore, during sampling, it is required to take 80% of the total volume of the sampling container, and connect to the bottom 40% of the sampling container to ensure that the sample is taken from the middle.

[0029] Furthermore, the glass plate can remove air bubbles from zinc acetate, ensuring a complete reaction.

[0030] Furthermore, the flow rate of the inert gas entering the Menthol washing bottle can be controlled by the valve on the pipeline to ensure the effective release of hydrogen sulfide.

[0031] Furthermore, the output of the high-pressure gas device is connected to multiple Monsieur wash bottles, enabling the purging of multiple Monsieur wash bottles and improving efficiency.

[0032] Furthermore, excess zinc acetate solution is used to absorb the escaping hydrogen sulfide gas, generating zinc sulfide precipitate. Excess iodine solution is added to oxidize the generated zinc sulfide. The remaining iodine is titrated with sodium thiosulfate standard solution, and the mass concentration of escapable hydrogen sulfide in the crude oil is calculated based on the titration results. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the closed sample transfer device of the present invention;

[0034] Figure 2 This is a schematic diagram of the inert gas purger structure of the present invention.

[0035] The components are: 1-Sampling container; 2-Hydrogen sulfide absorber; 3-Needle; 4-Latex pad; 5-Glass plate; 6-Inert gas purger; 7-Valve; 8-Fixing cover. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings:

[0037] The combined apparatus for determining hydrogen sulfide content in crude oil according to the present invention includes a Mendel washing bottle, a sealed sample transfer device, and an inert gas purger 6.

[0038] like Figure 1 As shown, the closed sample transfer device includes a sampling barrel 1 and a hydrogen sulfide absorber 2. The sampling barrel 1 contains crude oil. A through hole is provided on the top of the sampling barrel 1. The through hole is covered with a latex pad 4. A needle 3 is provided on the latex pad 4. The head of the needle 3 penetrates the latex pad 4 and extends into the part above the crude oil surface in the inner cavity of the sampling barrel 1 through the through hole. The tail of the needle 3 is connected to the input end of the hydrogen sulfide absorber 2.

[0039] There are at least two hydrogen sulfide absorbers 2 connected in series. The hydrogen sulfide absorber 2 contains a zinc acetate solution. The bottom of the hydrogen sulfide absorber 2 is the gas inlet and the top is the gas outlet. The hydrogen sulfide absorber 2 contains a glass plate 5 with multiple small through holes. The glass plate 5 is located in the zinc acetate solution and can remove air bubbles in the zinc acetate to ensure a complete reaction.

[0040] The inert gas purger 6 includes multiple fixed covers 8 and a high-pressure gas device. The fixed covers 8 are square tubes with a length less than the height of the Menthol washing bottle and a width not less than the diameter of the Menthol washing bottle. The fixed covers 8 are vertically arranged and have a notch on one side. The high-pressure gas device stores nitrogen gas. In this embodiment, the high-pressure gas device uses a high-pressure gas cylinder.

[0041] When performing closed-loop sample transfer, the inner cavity of the Meng's wash bottle is connected to the part below the crude oil surface in the inner cavity of sampling bucket 1. The inner cavity of the Meng's wash bottle is connected to the bottom 40% of the sampling bucket 1 via a pipe. The part above the crude oil surface in the inner cavity of sampling bucket 1 is connected to the inlet end of the hydrogen sulfide absorber 2.

[0042] During inert gas purging, the Mendelssohn wash bottles are connected to both the output of the high-pressure gas device and the inlet of the hydrogen sulfide absorber 2. The output of the high-pressure gas device is connected to multiple Mendelssohn wash bottles, which are placed in a fixed shroud 8, improving purging efficiency. A pipeline connects the Mendelssohn wash bottles to the output of the high-pressure gas device, and a valve 7 is installed on the pipeline. The flow rate of the inert gas entering the Mendelssohn wash bottles can be controlled through the valve 7 to ensure effective hydrogen sulfide precipitation.

[0043] First, the sampling container 1 was modified by drilling a hole in the upper part and attaching a latex pad 4 with good sealing performance. By using a syringe needle 3 to penetrate the latex pad 4, the hydrogen sulfide gas that had escaped prematurely during the transportation of the upper part of the sampling container 1 could be quickly extracted. The extracted hydrogen sulfide gas was quickly transferred to the hydrogen sulfide absorber 2 containing zinc acetate solution. After the needle 3 was pulled out, the latex pad 4 automatically restored its seal. This part of the hydrogen sulfide was calculated separately based on the total amount of sample, which improved the accuracy of the final analysis results.

[0044] During the sample weighing process into the Meng's wash bottle, we specially process a universal cap. A hole is drilled in the middle of the cap to insert a rigid, corrosion-resistant PC plastic tube. One end of the plastic tube extends 40% into the bottom of the bottle to ensure that the sample is taken from the middle. When sampling, it is required to take 80% of the total volume of the sample bottle. The other end is connected to a flexible tube, which in turn connects to the stainless steel tube in the middle of the rubber stopper at the top of the Meng's wash bottle. The purpose of adding the flexible tube is to facilitate the weighing operation. The flexible tube has good plasticity, and the rubber stopper has good sealing performance, which can achieve sealed weighing during the weighing process and prevent hydrogen sulfide from escaping and causing harm to the operator.

[0045] The purpose of the inert gas purger 6 is to provide nitrogen gas at a stable pressure, agitating the oil to ensure the uniform and complete escape of hydrogen sulfide. Using this combined device to analyze volatile hydrogen sulfide in crude oil, the device pre-collects the hydrogen sulfide that has escaped before weighing, achieving fully sealed weighing and ensuring the complete escape of hydrogen sulfide from the sample. This not only prevents harm to operators and analysts caused by hydrogen sulfide and protects the atmospheric environment, but also improves the accuracy of analytical results—a triple benefit.

[0046] The crude oil sample was purged with inert nitrogen gas, causing any escapable hydrogen sulfide to escape along with the nitrogen. The escaped hydrogen sulfide was then absorbed by an excess of zinc acetate solution, forming a zinc sulfide precipitate. An excess of iodine solution was added to oxidize the precipitate, and the remaining iodine was titrated with a standard sodium thiosulfate solution. The mass concentration of escapable hydrogen sulfide in the crude oil was calculated based on the titration results, expressed in mg / kg. The entire analytical process includes four main steps: sampling, weighing, sample testing, and calculation.

[0047] The specific process for determining the hydrogen sulfide content in crude oil is as follows:

[0048] 1. Use sampling container 1 to take samples. When taking samples, pay attention to sealing the container and avoid shaking to reduce the impact of hydrogen sulfide escaping. The amount taken should not be less than 2.0 liters. The optimal amount of sample is 4 / 5 of the total volume of the sampling container. After sampling, send the sample to the laboratory as soon as possible to avoid the loss of hydrogen sulfide. Before taking samples, weigh the empty container and record the mass.

[0049] 2. Weigh the total mass of the sample (including the empty container). Use the needle 3 connected to the hydrogen sulfide absorber 2 to quickly penetrate the latex pad 4 at the top of the sampling container 1. The hydrogen sulfide absorber 2 contains 50 ml of 5 g / L zinc acetate solution. The hydrogen sulfide that has escaped from the sampling container 1 in advance quickly enters the hydrogen sulfide absorber 2 and reacts chemically with the zinc acetate solution to form zinc sulfide precipitate.

[0050] 3. As shown in Table 1, weigh a certain mass of sample into a Mondl wash bottle. When weighing, connect the Mondl wash bottle with the lid and pipeline to ensure that the sampling is sealed and the sample is taken from the middle. Tilt the sampling bucket 1 and let the crude oil in the sampling bucket 1 flow into the Mondl wash bottle through the pipeline.

[0051] Table 1. Reference Amount for Sample Weighing

[0052]

[0053] 4. Add 150ml of 200# solvent oil to a Menger wash bottle to dilute the oil. Quickly cover the bottle with a ground glass stopper with a glass tube. The bottom of the tube, which extends to the bottom of the oil, has six small holes to ensure that nitrogen gas is blown into the oil evenly. Connect the inlet tube of the glass stopper to the nitrogen line and the outlet tube to the absorber containing zinc acetate solution. Select a 2-stage or 3-stage absorber according to the hydrogen sulfide concentration. Connect at least two absorbers to ensure complete absorption of hydrogen sulfide. Connect the outlet of the last absorber to a wet gas flow meter to control the flow rate of 270-330ml / min.

[0054] 5. Place the absorber into the fixed cover 8 of the nitrogen splitter, place the Meng's wash bottle at the front end of the fixed cover 8, open the regulating valve of the nitrogen splitter, and slowly adjust the flow rate until the sample is fully bubbled. There is a glass plate 5 with micropores in the middle of the absorber, which is used to disperse large bubbles into small bubbles, so that hydrogen sulfide and zinc acetate solution can fully react chemically. The purging time should be until the solution inside the absorber turns white and turbid, indicating that the hydrogen sulfide has been completely absorbed. The nitrogen splitter has 4 half-masks and 4 nitrogen lines, which can meet the requirements of multi-stage absorption.

[0055] 6. After the purging is completed, remove the absorber and the absorber head. Sequentially add 10 mL of iodine solution with a concentration of 5 g / L and 10 mL of hydrochloric acid solution with a mass ratio of 1:11 to each absorber. Since the iodometric method requires a chemical reaction to occur in an acidic environment and the best pH value is 5, dilute hydrochloric acid with a ratio of 1:11 is added. Install the absorber head, and gently agitate the solution at the absorber inlet with an ear syringe to make it mix evenly. After reacting for 2 - 3 minutes, transfer the solution into a 500 ml iodine flask and store it in the dark for 10 minutes.

[0056] 7. Titrate with 0.02 mol / L sodium thiosulfate solution. When approaching the end point, add 1 - 2 ml of 5 g / L starch indicator, and titrate until the blue color disappears. Calculate the mass of hydrogen sulfide M1 in sampling bucket 1 and the mass of hydrogen sulfide M2 in the Monshi wash bottle.

[0057] 8. Calculate the results.

[0058] 8.1. Calculation of hydrogen sulfide prematurely escaped during transportation.

[0059] Mass concentration of hydrogen sulfide (mg / kg), X1 = {M1 / (M_total - M_empty)} * 1000000.

[0060] Ml: Mass of hydrogen sulfide in sampling bucket 1, unit is (g).

[0061] M_total: Total mass of the sample and the empty bucket, unit is (g).

[0062] M_empty: Mass of the empty bucket, unit is (g).

[0063] 8.2. Calculation of hydrogen sulfide in the weighed sample.

[0064] Mass concentration of hydrogen sulfide (mg / kg), X2 = {M2 / M_Meng} * 1000000.

[0065] M2: Mass of hydrogen sulfide in the Monshi wash bottle, unit is (g).

[0066] M_Meng: Mass of the sample weighed into the Monshi wash bottle.

[0067] 8.3. X_total = X1 + X2.

[0068] X_total: Final total mass concentration of hydrogen sulfide, (mg / kg). <​​

Claims

1. A method for determining a combined apparatus based on the hydrogen sulfide content in crude oil, characterized by, The combined device comprises a Meng's washing bottle, a closed sample transfer device and an inert gas purger (6); The closed sample transfer device comprises a sampling barrel (1) and a hydrogen sulfide absorber (2), and the sampling barrel (1) is provided with crude oil; when the closed sample transfer is performed, the inner cavity of the Meng's washing bottle is communicated with the part below the crude oil liquid level in the inner cavity of the sampling barrel (1), and the part above the crude oil liquid level in the inner cavity of the sampling barrel (1) is communicated with the gas inlet end of the hydrogen sulfide absorber (2); The inert gas purger (6) comprises a high-pressure gas device, and when the inert gas purging is performed, the Meng's washing bottle is communicated with the output end of the high-pressure gas device and the gas inlet end of the hydrogen sulfide absorber (2); A through hole is arranged above the sampling barrel (1), and a latex cushion (4) is arranged on the through hole; a needle (3) is arranged on the latex cushion (4), the head of the needle (3) penetrates through the latex cushion (4) and extends into the part above the crude oil liquid level in the inner cavity of the sampling barrel (1) through the through hole, and the tail of the needle (3) is communicated with the gas inlet end of the hydrogen sulfide absorber (2); The inner cavity of the Meng's washing bottle is communicated with the barrel bottom 40% of the sampling barrel (1) through a pipeline; The hydrogen sulfide absorber (2) is provided with a zinc acetate solution; The determination method Comprises the following processes: First, the closed sample transfer is performed, the hydrogen sulfide gas in the inner cavity of the sampling barrel (1) enters the hydrogen sulfide absorber (2) to generate chemical reaction to form zinc sulfide precipitation, the mass of the hydrogen sulfide in the sampling barrel (1) is calculated according to the amount of the zinc sulfide precipitation; then, a certain mass of the crude oil in the sampling barrel (1) is weighed and flowed into the Meng's washing bottle; Then, the inert gas purging is performed, the inert gas is introduced into the Meng's washing bottle, the hydrogen sulfide gas generated in the Meng's washing bottle enters the hydrogen sulfide absorber (2) to generate chemical reaction to form zinc sulfide precipitation, and the mass of the hydrogen sulfide in the Meng's washing bottle is calculated according to the amount of the zinc sulfide precipitation.

2. The assay method according to claim 1, characterized by The hydrogen sulfide absorber (2) is provided with a glass plate (5) with multiple through holes, and the glass plate (5) is located in the zinc acetate solution.

3. The assay method according to claim 1, characterized by, A pipeline is arranged between the Meng's washing bottle and the output end of the high-pressure gas device, and a valve (7) is arranged on the pipeline.

4. The assay method according to claim 1, characterized by, The output end of the high-pressure gas device is communicated with multiple Meng's washing bottles.

5. The assay method according to claim 1, characterized by, Nitrogen is stored in the high-pressure gas device.

6. The assay method of claim 1, wherein Comprises the following processes: The mass concentration X1 of the hydrogen sulfide in the sampling barrel (1) is X1 = {M1 / (Mtotal-Mempty)}*1000000; Wherein M1 is the mass of the hydrogen sulfide in the sampling barrel (1), unit: g; Mtotal is the total mass of the sample and the empty barrel, unit: g; Mempty is the mass of the empty barrel, unit: g; The mass concentration X2 of the hydrogen sulfide in the Meng's washing bottle is X2 = {M2 / Mmeng}*1000000; Wherein M2 is the mass of the hydrogen sulfide in the Meng's washing bottle, unit: g; Mmeng is the mass of the sample weighed into the Meng's washing bottle; The final total mass concentration Xtotal of the hydrogen sulfide is Xtotal = X1+X2. The process of calculating the mass of the hydrogen sulfide in the sampling barrel (1) or the Meng's washing bottle is that 10 mL of iodine solution with a concentration of 5 g / L and 10 mL of hydrochloric acid solution with a mass ratio of 1:11 are added into the hydrogen sulfide absorber (2), mixed uniformly, titrated with sodium thiosulfate solution, 1-2 ml of starch indicator is added at the near end point, titrated until the blue color disappears, and the mass of the hydrogen sulfide in the sampling barrel (1) or the Meng's washing bottle is calculated. ​ 7. The assay method according to claim 6, characterized in that, ​

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