Spraying type corrosion inhibitor filling and concentration distribution testing multiphase flow loop

Abstract

The utility model discloses a multi-phase flow loop for filling a spraying type corrosion inhibitor and testing concentration distribution. Comprising the steps that a corrosion inhibitor is added into a liquid storage tank through a metering pump to be mixed with a liquid part and then sprayed out through a spray head arranged on a straight pipe, gas can carry the liquid to enter a loop, and then the distribution of the corrosion inhibitor in the loop is tested. After entering the test section, two roads can be selected for testing. A horizontal testing section can be selected for testing, and finally the liquid returns to the liquid storage tank after passing through the electromagnetic flowmeter; uphill and downhill corrosion test sections can also be selected, and the liquid flows back to the liquid storage tank after being metered by the flowmeter. The corrosion inhibitor concentration distribution experiment device is simple in structure and easy to install, can be used for corrosion inhibitor concentration distribution experiments under industrial pipe flow of various working conditions, and provides guidance for a fluctuating pipeline on-site corrosion inhibitor filling process.

Description

Technical Field

[0001] This utility model patent designs a corrosion testing device, specifically a spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop for petrochemical industry. Background Art

[0002] In 1959, a gathering pipeline in the LACQ gas field in France, which had long been filled with corrosion inhibitors, suffered severe corrosion on its inner wall. The corrosion primarily occurred in the upper half of the pipeline (between 9 and 3 o'clock), but the bottom of the entire gathering pipeline remained largely uncorroded due to the protection provided by the corrosion inhibitor. Since then, cases of severe corrosion in the upper half of gathering pipelines have occurred in countries such as Canada, Indonesia, and the United States. The natural gas transportation industry refers to this type of corrosion as top corrosion. A key factor in this type of corrosion is the uneven distribution of corrosion inhibitors within the pipeline. Therefore, understanding the distribution of corrosion inhibitors is crucial for industrial safety.

[0003] Corrosion within pipelines not only causes enormous economic losses and triggers various catastrophic accidents, but also consumes valuable and limited resources and energy, severely pollutes the environment, and, to a certain extent, threatens human survival and development. Consider a metal pipeline transporting acidic liquid. Without corrosion inhibitors, the inner surface of the pipeline will rapidly react chemically with the acidic liquid, gradually dissolving metal atoms and forming rust spots, pits, and cracks. Over time, these corroded areas will expand and deepen, seriously affecting the strength and sealing of the pipeline. Liquid leakage may occur, resulting in not only wasted resources but also potentially causing safety accidents and environmental pollution. However, when appropriate corrosion inhibitors are added to the transported liquid, the inhibitor molecules adsorb onto the metal surface of the pipeline, forming a protective film. This protective film effectively blocks direct contact between the acidic liquid and the metal, significantly reducing the rate of corrosion reactions. This significantly extends the pipeline's service life, reduces maintenance and replacement costs, and ensures safe and stable pipeline transportation. For example, pipelines used to transport crude oil often face complex corrosive environments. The addition of specific corrosion inhibitors can effectively mitigate pipeline corrosion caused by corrosive components such as sulfides and chlorides in crude oil, ensuring continuous production and reducing the risk of downtime and equipment damage caused by pipeline corrosion. Therefore, corrosion inhibitors play a vital role in preventing pipeline corrosion, ensuring the safe, stable, and efficient operation of pipeline systems. Utility Model Content

[0004] A spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop, characterized in that: a compressor (1) is connected to a nitrogen generator (3) through a hose (2), and the produced nitrogen enters a nitrogen tank (5) through a hose (4), and after passing through an outlet flow control valve (6), the nitrogen enters a first three-way (10); a carbon dioxide tank (7) is connected to a compressor (8), and carbon dioxide enters the first three-way (10) after passing through an outlet flow control valve (9), and the two paths merge into a pipe with a nozzle (20). The corrosion inhibitor flows from the liquid storage tank 1 (11) through the outlet flow control valve 3 (12) into the metering pump (13), is pressurized by the metering pump (13), and then flows into the liquid storage tank 2 (15) through the outlet flow control valve 4 (14). The liquid flows out of the liquid storage tank 2 (15), passes through the outlet flow control valve 5 (16), and enters the variable frequency centrifugal pump (17) with a variable frequency motor (18). After being ejected through the nozzle (20), it enters the second three-way (22). The second three-way (22) is divided into two The outlet is connected in sequence to gate valve 1 (23), pressure gauge 1 (24), flange 1 (25), uphill bend test section 1 (26), flange 2 (27), uphill straight pipe test section (28), flange 3 (29), uphill bend test section 2 (30), flange 4 (31), slope top horizontal test section (32), pressure gauge 2 (33), flange 5 (34), downhill bend test section 1 (35), flange 6 (36), downhill straight pipe test section (37), flange 7 (38). ), downhill bend test section two (39), flange eight (40), pressure gauge three (41), outlet flow control valve six (42), water stop valve (43), the other outlet is connected in sequence to gate valve two (44), pressure gauge four (45), horizontal test section (46), outlet flow control valve seven (47), horizontal bend test section (48), the two paths converge at the third tee (49), and the liquid flows back to the liquid storage tank two (15) after passing through the electromagnetic flow meter (50) and the inlet control valve (51).

[0005] A spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop is characterized in that: the liquid added with corrosion inhibitor under working conditions can be converted into mist droplets through a nozzle (20), so that the gas can carry the liquid droplets and flow along the pipeline, thereby testing the distribution of gas-phase pipeline corrosion inhibitor on the pipeline wall.

[0006] A spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop is characterized in that the corrosion inhibitor is pressurized and the amount of corrosion inhibitor added is controlled by a metering pump (13).

[0007] A spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop is characterized in that: after passing through the slope top horizontal test section (32), the horizontal test section (46), the horizontal curved pipe test section (48), the uphill straight pipe test section (28), and the downhill straight pipe test section (37), electrochemical signals at different clock positions can be detected online, and the corrosion inhibitor adhesion condition can be detected by scanning the corrosion inhibitor characteristic elements.

[0008] The pressure gauge can detect the pressure value in real time, which is beneficial for controlling variables; the compressors (1) and (8) can adjust the gas pressure; the variable frequency centrifugal pump (17) has a variable frequency speed regulation function, and controls the speed and lift in real time through the variable frequency motor (18); the quantitative pump (13) can adjust the amount of corrosion inhibitor added.

[0009] The corrosion inhibitor nozzle design can make the corrosion inhibitor evenly distributed, better coated on the pipeline wall, and can simulate the scenario of adding corrosion inhibitor on site.

[0010] The inclination angle is adjustable and can be adjusted according to the site. The corrosion inhibitor concentration distribution test can be carried out in locations such as undulating pipes and elbows that are prone to corrosion, difficult to apply corrosion inhibitors, and have complex changes in corrosion inhibitor concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the structure of this utility model patent;

[0012] Figure 2 This is a schematic diagram of the longitudinal section of the utility model patent;

[0013] Figure 3 This is a schematic cross-sectional view of the utility model patent.

[0014] The figure includes: 1. Compressor 1, 2. Hose 1, 3. Nitrogen generator, 4. Hose 2, 5. Nitrogen tank, 6. Inlet control valve 1, 7. Carbon dioxide tank, 8. Compressor 2, 9. Inlet control valve 2, 10. First three-way valve, 11. Liquid storage tank 1, 12. Outlet flow control valve 3, 13. Dosing pump, 14. Outlet flow control valve 4, 15. Liquid storage tank 2, 16. Outlet flow control valve 5, 17. Frequency conversion centrifugal pump, 18. Frequency conversion motor, 19. Outlet flow control valve 6, 20. Nozzle, 21. Straight pipe with nozzle, 22. Second three-way valve, 23. Gate valve 1, 24. Pressure gauge 1, 25. Flange 1, 26. Uphill bend test section 1, 27. Flange 2, 2 8. Uphill straight pipe test section, 29. Flange three, 30. Uphill bend test section two, 31. Flange four, 32. Slope top horizontal test section, 33. Pressure gauge two, 34. Flange five, 35. Downhill bend test section one, 36. Flange six, 37. Downhill straight pipe test section, 38. Flange seven, 39. Downhill bend test section two, 40. Flange eight, 41. Pressure gauge three, 42. Outlet flow control valve eight, 43. Stop valve, 44. Gate valve two, 45. Pressure gauge four, 46. Horizontal test section, 47. Outlet flow control valve nine, 48. Horizontal bend test section, 49. Third tee, 50. Electromagnetic flowmeter, 51. Inlet flow control valve, test hole (52-60). DETAILED DESCRIPTION

[0015] like Figure 1 As shown, a spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop is installed. Before the experiment, first fill the liquid into the second liquid storage tank (15), and then fill the corrosion inhibitor into the first liquid storage tank (11). The liquid level is preferably controlled at 4 / 5 of the height of the liquid storage tank. Then, according to the conditions required by the experiment, the frequency conversion motor (18), the outlet flow control valve four (12), the outlet flow control valve two (16), the outlet flow control valve (9), the outlet flow control valve (6), and the inlet flow control valve (51) are adjusted. The test path is selected according to the selection of the gate valve opening and closing.

[0016] If industrial needs require, the horizontal pipeline test section and the uphill and downhill pipeline test section can be tested simultaneously. The outlet control valve three (12) and outlet control valve one (16), inlet control valve (51), gate valve one (23) and gate valve two (44) of the liquid storage tank are opened, and the corrosion inhibitor enters the metering pump (13) from the liquid storage tank one (11), starts the variable frequency centrifugal pump (9) to increase the pressure, and then enters the pipeline (16) with the nozzle; the corrosion inhibitor is pressurized by the metering pump (13) and enters the liquid storage tank two (15) to mix with the liquid therein, and is pressurized by the variable frequency centrifugal pump and enters the nozzle (20), so that the liquid added with the corrosion inhibitor under the working conditions becomes mist droplets, so that the gas can carry the liquid droplets to flow along the pipeline, and the distribution of the gas phase pipeline corrosion inhibitor on the pipeline wall is tested. After the air enters the compressor (1), it enters the nitrogen generator (3) through the hose (2). The nitrogen produced enters the nitrogen tank (5) and then enters the first tee (10); the carbon dioxide enters the first tee (10) from the carbon dioxide tank (7). The two paths merge at the first tee (10) and enter the pipeline (21). The gas carries the liquid sprayed from the nozzle (20) and enters the second tee (22). Since the gate valve 1 (23) and the gate valve 2 (44) are opened at the same time, the liquid flows in two ways. One path flows through the horizontal pipe section, and the other flows through the horizontal pipe section. After passing through the polytetrafluoroethylene horizontal straight pipe test section (46) and the polytetrafluoroethylene horizontal elbow test section (48), the fluid flows to the third tee (49); one path is measured by the first pressure gauge (24) and then enters the uphill polytetrafluoroethylene test section 25-31, and after being measured by the second pressure gauge (33), it enters the downhill polytetrafluoroethylene test section 34-40, and after being measured by the third pressure gauge (41), it flows to the third tee (49); the two paths of fluid merge at the third tee (49), enter the electromagnetic flowmeter (50) for measurement, and then return to the liquid storage tank (15). The uphill bend test section 1 (26), uphill bend test section 2 (30), downhill bend test section 1 (35), downhill bend test section 2 (39) are all connected by flange 1 (25), flange 2 (27), flange 3 (29), flange 4 (31), flange 5 (34), flange 6 (36), flange 7 (38), and flange 8 (40). The pipelines can be replaced according to needs to achieve the change of uphill and downhill inclination angles. Electrochemical test sensors 56, 57, 58, 59, and 60 are equidistantly arranged in the polytetrafluoroethylene test sections 25-31, 34-40, 32, 46, and 48. Electrochemical test sensors are arranged at four positions on the cross section, namely, 3 o'clock 52, 6 o'clock 53, 9 o'clock 54, and 12 o'clock 55.

[0017] Air tightness test: The air tightness test is to ensure the stability of system pressure and medium content, and to ensure the safety of the experiment. Close all outlet valves and pass nitrogen into the liquid storage tank through a high-pressure gas cylinder to 10kgf·cm -2, use soapy water to check all possible leaks, maintain pressure for half an hour, then release to normal pressure, add 4 / 5 volume of water to the liquid storage tank 1, and then fill with nitrogen to 1kgf·cm -2 Use the same method to check air tightness.

[0018] Deoxygenation of the device: To ensure that there is no interference from ambient oxygen in the experiment, after the airtightness is qualified, the nitrogen tank (5) continues to be filled with nitrogen to increase the annular pressure to 10kgf·cm -2 Then, release to normal pressure, repeat the above process 5 times. Then, add distilled water to the second liquid storage tank (15), heat it to 60℃, and fill it with nitrogen from the bottom of the second liquid storage tank (15) until the pressure of the loop system reaches 5kgf·cm -2 , release the pressure in the loop system to normal pressure, repeat this process 10 times, and it is considered that the test loop is in an oxygen-free state at this time.

[0019] Pressure regulation: Real-time pressure detection through pressure gauge and pressure regulation through variable frequency centrifugal pump

[0020] Solution preparation: During the experiment, two sets of experimental plans were drawn up. Plan 1 directly retrieved materials from industrial production and brought them into the experimental device for experiment, but it was necessary to consider whether the materials met the experimental safety requirements; Plan 2 prepared the solution by itself. If the solution contained salt ions, the experimental liquid was prepared according to the concentration requirements and added to the liquid storage tank. If the liquid was saturated with a certain corrosive gas, it could be continuously introduced into the liquid storage tank through a high-pressure gas cylinder.

Claims

1. A multiphase flow loop for spraying corrosion inhibitor filling and concentration distribution testing, characterized by: The compressor (1) is connected to the nitrogen generator (3) through a hose (2), and the generated nitrogen enters the nitrogen tank (5) through a hose (4), and after passing through the outlet flow control valve (6), the nitrogen enters the first three-way (10); the carbon dioxide tank (7) is connected to the compressor (8), and the carbon dioxide enters the first three-way (10) after passing through the outlet flow control valve (9), and the two paths merge into a pipeline (21) with a nozzle (20); the corrosion inhibitor is discharged from the liquid storage tank (11) through the outlet The liquid flows through the flow control valve 3 (12) into the metering pump (13), and after being pressurized by the metering pump (13), flows through the outlet flow control valve 4 (14) into the liquid storage tank 2 (15). The liquid flows out of the liquid storage tank 2 (15), flows through the outlet flow control valve 5 (16) into the variable frequency centrifugal pump (17) with a variable frequency motor (18), and after being sprayed through the nozzle (20), flows into the second three-way (22). The second three-way (22) is divided into two outlets, one of which is connected to the gate valve 1 ( 23), pressure gauge 1 (24), flange 1 (25), uphill bend test section 1 (26), flange 2 (27), uphill straight pipe test section (28), flange 3 (29), uphill bend test section 2 (30), flange 4 (31), slope top horizontal test section (32), pressure gauge 2 (33), flange 5 (34), downhill bend test section 1 (35), flange 6 (36), downhill straight pipe test section (37), flange 7 (38), downhill bend test Section 2 (39), flange 8 (40), pressure gauge 3 (41), outlet flow control valve 6 (42), water stop valve (43), the other outlet is connected in sequence to gate valve 2 (44), pressure gauge 4 (45), horizontal test section (46), outlet flow control valve 7 (47), horizontal elbow test section (48), the two paths converge at the third tee (49), and the liquid flows back to the liquid storage tank 2 (15) after passing through the electromagnetic flow meter (50) and the inlet control valve (51).

2. A spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop according to claim 1, characterized in that: The liquid to which the corrosion inhibitor is added under working conditions can be transformed into mist droplets through the nozzle (20), so that the gas can carry the liquid droplets and flow along the pipeline, thereby testing the distribution of the gas phase pipeline corrosion inhibitor on the pipeline wall.

3. A spray-type corrosion inhibitor filling and concentration distribution test multiphase flow loop according to claim 1, characterized in that The corrosion inhibitor is pressurized and the amount of corrosion inhibitor added is controlled by a metering pump (13).

4. The multiphase flow loop for spraying corrosion inhibitor filling and concentration distribution testing according to claim 1, characterized in that: After passing through the slope top horizontal test section (32), the horizontal test section (46), the horizontal curved pipe test section (48), the uphill straight pipe test section (28), and the downhill straight pipe test section (37), the electrochemical signals at different clock positions can be detected online, and the corrosion inhibitor adhesion condition can be detected by scanning the corrosion inhibitor characteristic elements.

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