Ultrasonic and pressure reduction synergistic dissociation device and method for hydrate blockage in pipeline

Abstract

The present application belongs to the technical field of oil and gas pipeline flow safety guarantee, and particularly relates to an ultrasonic and pressure reduction synergistic dissociation device and method for pipeline hydrate blockage, comprising a high-pressure pipeline model, a constant temperature control device, an ultrasonic loading device, an automatic back pressure control device, a gas-liquid separation device, a liquid recovery and measurement device, a visual acquisition device and a data acquisition and analysis device. The ultrasonic loading device comprises an ultrasonic generator and an outer clamping ultrasonic transducer arranged along the axial direction of the pipeline. The transducer is attached to the outer wall of the pipeline through an arc surface coupling die, realizing non-invasive ultrasonic transmission. The first time when the pressure reaches the set back pressure is taken as the stage turning point, and the dissociation process is divided into a main dissociation stage and a back pressure maintaining dissociation stage. According to a preset strategy, ultrasonic action is applied before pressure reduction, in the main dissociation stage and / or the back pressure maintaining dissociation stage. The present application can improve the blockage dissociation efficiency, reduce invalid energy input, and enhance the controllability and safety of the blockage removal process.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas pipeline flow safety assurance technology, and particularly relates to an ultrasonic and pressure reduction synergistic dissociation device and method for pipeline hydrate blockage. Background Technology

[0002] Gas hydrates are solid crystalline substances formed under low temperature and high pressure conditions. During deepwater oil and gas extraction, gas storage facility production, and multiphase pipeline transportation, the coexistence of gas and water phases, coupled with changes in pressure, temperature, and flow state, easily induces the formation, deposition, and accumulation of hydrates, leading to blockages in pipelines, wellbores, or surface gathering and transportation systems. Hydrate blockages can cause abnormal pipeline pressure drops, reduced transportation capacity, and in severe cases, equipment failure and safety accidents. Therefore, achieving rapid and controllable dissociation of solid hydrate blockages within pipelines is a key technical issue in ensuring the flow of deepwater oil and gas, gas storage facility production and transportation, and natural gas gathering and transportation.

[0003] Existing methods for hydrate dissociation mainly include depressurization, thermal stimulation, chemical injection, gas replacement, and combinations thereof. Depressurization offers advantages such as simple operation and low energy consumption; however, hydrate depressurization dissociation is an endothermic phase change process, which can easily cause localized temperature drops, reducing the dissociation driving force and potentially inducing ice formation, secondary hydrate formation, and flow channel obstruction, leading to a decrease in the dissociation rate. Furthermore, direct depressurization may cause a large release of gas in a short period, increasing the difficulty of gas metering, downstream treatment, and process safety control. While auxiliary methods such as thermal stimulation, chemical injection, and gas replacement can improve dissociation conditions, they still suffer from low energy utilization efficiency, limited range of action, uneven reagent distribution, corrosion or environmental risks, and difficulties in process control.

[0004] Ultrasound, as a physical enhancement method, can promote the destruction of hydrate blockage structures and the reconstruction of gas-liquid channels through cavitation, mechanical disturbance, interface renewal, and local thermal effects, providing a new approach to enhance hydrate dissociation. However, existing ultrasound-assisted dissociation technologies mostly focus on the impact of ultrasound power, frequency, or intensity on overall dissociation efficiency, lacking consideration of the matching relationship between the timing of ultrasound application and the depressurization dissociation stage. Since the depressurization dissociation process of hydrates has distinct stages, the response to ultrasound and the energy conversion benefits differ at different stages. Continuous or indiscriminate application of ultrasound can easily lead to energy input redundancy, making it difficult to achieve efficient and controllable dissociation.

[0005] Therefore, there is an urgent need for a pipeline hydrate blockage dissociation device and method that can stage the ultrasonic action and depressurization process, and simultaneously achieve real-time online monitoring of key characteristics such as pressure, temperature, and gas-water production, so as to improve dissociation efficiency, reduce energy waste, and enhance the controllability and safety of the unblocking process. Summary of the Invention

[0006] The purpose of this invention is to provide a device and method for ultrasonic and pressure-reducing synergistic dissociation of hydrate blockage in pipelines. Based on the staged evolution characteristics of the hydrate pressure-reducing dissociation process, an external clamping ultrasonic action and pressure-reducing synergistic dissociation system is established. This system allows ultrasonic energy to intervene at the stage when the hydrate blockage structure is most responsive, thereby promoting the destruction of the blockage structure, the formation of release channels, and the discharge of gaseous and liquid products. This solves the problems of blind enhancement of the dissociation process, insufficient energy utilization, and low process control precision in existing dissociation processes.

[0007] To achieve the above objectives, the specific technical solution of the ultrasonic and pressure-reducing synergistic dissociation device and method for hydrate blockage in pipelines according to the present invention is as follows: An ultrasonic and pressure-reducing synergistic dissociation device for hydrate blockage in pipelines includes a high-pressure pipeline model, a gas injection device, a liquid injection device, a constant temperature control device, an ultrasonic loading device, an automatic back pressure control device, a gas-liquid separation device, a gas disposal device, a liquid recovery measurement device, a visual acquisition device, and a data acquisition and analysis device. The high-pressure pipeline model is equipped with a gas injection port, a liquid injection port, a discharge port, a forced discharge port, a pressure detection port, and a temperature detection port. At least one end of the high-pressure pipeline model is equipped with an end-visible flange assembly. The gas injection device is connected to the gas injection port, the liquid injection device is connected to the liquid injection port, the discharge port is connected to the gas-liquid separation device via the automatic back pressure control device, the gas outlet of the gas-liquid separation device is connected to the gas disposal device, and the liquid outlet of the gas-liquid separation device is connected to the liquid recovery measurement device. The constant temperature control device is located on the outside of the high-pressure pipeline model to maintain the high-pressure pipeline model at a preset temperature. The ultrasonic loading device includes an ultrasonic generator and multiple externally clamped ultrasonic transducers. The multiple externally clamped ultrasonic transducers are arranged along the axial direction of the high-pressure pipeline model and are electrically connected to the output end of the ultrasonic generator through transmission cables. The visual acquisition device is positioned toward the end visual flange assembly. The pressure detection port is connected to the pressure detection device, and the temperature detection port is connected to the temperature detection device. The data acquisition and analysis device is connected to the pressure detection device, the temperature detection device, the gas flow meter, the liquid flow meter, the liquid recovery measurement device, and the ultrasonic generator, respectively.

[0008] Furthermore, the externally clamped ultrasonic transducers are arranged in pairs to form an ultrasonic transducer group; each externally clamped ultrasonic transducer includes an ultrasonic transducer body and an arc-shaped coupling head disposed at its output end, the arc-shaped coupling head being made of titanium alloy; the inner side of the arc-shaped coupling head is provided with an arc-shaped coupling surface that matches the curvature of the outer wall of the high-pressure pipeline model, the arc-shaped coupling surface being attached to the outer wall of the high-pressure pipeline model; the two oppositely arranged arc-shaped coupling heads are clamped to the outer periphery of the high-pressure pipeline model by bolts.

[0009] Furthermore, the temperature detection device includes multiple temperature detection sections spaced apart along the axial direction of the high-pressure pipeline model, each temperature detection section being provided with multiple thermocouples with different insertion depths, and the temperature measuring ends of the multiple thermocouples being distributed along the radial direction of the high-pressure pipeline model; at least a portion of the temperature detection sections are located between adjacent ultrasonic transducer groups.

[0010] Furthermore, the end-visible flange assembly includes an end flange, a circular clamping cap, a transparent sight glass, and a sealing ring; the end flange is connected to the end of the high-pressure pipeline model, and the sealing ring is disposed between the end flange and the end of the high-pressure pipeline model; the end flange has an observation through hole at its center that communicates with the inner cavity of the high-pressure pipeline model, the transparent sight glass covers the observation through hole, and the circular clamping cap presses the transparent sight glass tightly against the end flange.

[0011] Furthermore, the housing of the external clamp-on ultrasonic transducer is provided with a lead hole, through which a transmission cable is connected to the terminal of the external clamp-on ultrasonic transducer, and the other end of the transmission cable is connected to the ultrasonic generator; the ultrasonic generator has multiple independent output channels, each of which is connected to an external clamp-on ultrasonic transducer at a different position, so that the external clamp-on ultrasonic transducers at different positions can be started and stopped independently and their operating parameters can be adjusted independently. The operating parameters include at least one of operating frequency, output power, duty cycle, and operating time.

[0012] Furthermore, the constant temperature control device includes a constant temperature water bath, a circulating hose, a liquid flow meter, multiple segmented jacketed pipes, and an insulation layer; the multiple segmented jacketed pipes are arranged at intervals along the axial direction of the high-pressure pipeline model, and the insulation layer is wrapped around the outside of each segmented jacketed pipe; each segmented jacketed pipe is provided with a liquid inlet at the bottom and a liquid outlet at the top, and adjacent segmented jacketed pipes are connected in series through the circulating hose, so that the constant temperature circulating liquid flows through each segmented jacketed pipe in a bottom-up manner; the liquid flow meter is arranged between the constant temperature water bath and the liquid inlet at the bottom of the first segmented jacketed pipe, and thermocouples are respectively arranged at the liquid inlet at the bottom of the first segmented jacketed pipe and the liquid outlet at the top of the last segmented jacketed pipe.

[0013] Furthermore, the automatic back pressure control device includes an automatic back pressure valve, a constant speed and constant pressure pump, and a constant temperature heating jacket; the discharge port of the high-pressure pipeline model is connected to the automatic back pressure valve through a connecting pipe, and a pressure sensor and a shut-off valve are installed on the connecting pipe; the constant speed and constant pressure pump is connected to the control end of the automatic back pressure valve, and a high-pressure container is installed on the pipeline between the constant speed and constant pressure pump and the automatic back pressure valve; the constant temperature heating jacket covers the outside of the automatic back pressure valve.

[0014] Furthermore, the gas treatment device includes a gas drying pipe, a gas flow meter, a shut-off valve, a flame arrester, a burner, and an igniter connected sequentially along the gas flow direction, and the gas inlet end of the gas drying pipe is connected to the gas outlet of the gas-liquid separation device.

[0015] A method for disintegrating solid hydrate blockages in a pipeline using the aforementioned device includes the following steps: S1. A hydrate blockage system is generated inside the high-pressure pipeline model, and the high-pressure pipeline model is maintained at a preset temperature by a constant temperature control device. S2. Release the free gas in the high-pressure pipeline model before depressurization and dissociation, and restore the pressure and temperature in the high-pressure pipeline model to a stable state; S3. Adjust the set back pressure of the automatic back pressure control device and start the pressure reduction dissociation to reduce the pressure in the high-pressure pipeline model according to the preset pressure reduction rate. S4. Taking the first time the pressure inside the high-pressure pipeline model reaches the set back pressure as the stage turning point, the dissociation process is divided into the main dissociation stage and the back pressure holding dissociation stage. S5. According to the preset dissociation strategy, the external clamp-on ultrasonic transducer is controlled by the ultrasonic generator to apply ultrasonic action before pressure reduction, during the main body dissociation stage and / or during the back pressure holding dissociation stage. S6. The pressure, temperature, gas production, water production, and ultrasonic working parameters during the dissociation process are recorded by the data acquisition and analysis device, and the dissociation process ends after the state in the high-pressure pipeline model meets the preset stability conditions.

[0016] Further, in step S2, the pressure after the free gas is released is 0.01~0.1 MPa higher than the hydrate phase equilibrium pressure under the corresponding operating conditions; in step S3, the set back pressure is 0.3~0.8 MPa, and the preset depressurization rate is 0.05~0.15 MPa / min; in step S5, the preset dissociation strategy includes one or more of the following: pre-ultrasonic mode, synchronous depressurization ultrasonic mode, staged depressurization ultrasonic mode, and late ultrasonic mode. The pre-ultrasonic mode applies ultrasonic action before starting depressurization; the synchronous depressurization ultrasonic mode applies ultrasonic action continuously from the start of depressurization until the dissociation process ends; the staged depressurization ultrasonic mode applies ultrasonic action only during the main dissociation stage and stops ultrasonic action when the pressure first reaches the set back pressure; and the late ultrasonic mode applies ultrasonic action during the dissociation stage while maintaining back pressure.

[0017] The ultrasonic and pressure-reducing synergistic dissociation device and method for hydrate blockage in pipelines, as disclosed in this invention, has the following advantages: This invention combines external clamping ultrasonic enhancement with a pressure-reducing dissociation process to achieve non-invasive, synergistic unblocking of pipeline hydrate solid blockages. The entire process requires no additional disturbance components inside the pipeline, nor the injection of chemical unblocking agents, thus avoiding the damage to the pipeline structure and interference with the pipeline transport medium caused by traditional unblocking methods. This provides an experimental basis and technical support for optimizing unblocking processes and developing engineering equipment for hydrate blockages in in-service oil and gas pipelines.

[0018] This invention establishes differentiated ultrasound intervention windows based on the phased evolution characteristics of the hydrate depressurization and dissociation process, enabling flexible implementation of various collaborative working modes such as pre-ultrasound, simultaneous depressurization ultrasound, phased depressurization ultrasound, and post-ultrasound. This design allows for precise matching of ultrasound energy input with the response characteristics of hydrates at different dissociation stages, avoiding energy redundancy caused by indiscriminate continuous energy supply and effectively improving the utilization efficiency of ultrasound energy.

[0019] This invention employs a clamping ultrasonic transducer assembly with a titanium alloy arc-shaped coupling head. The titanium alloy head combines excellent structural strength, corrosion resistance, and vibration transmission efficiency, ensuring stable coupling and transmission of ultrasonic energy into the pipeline. Furthermore, the clamping structure eliminates the need for pipeline modifications, improving the ease of installation, disassembly, and adjustment of the device's position.

[0020] This invention includes a combined axial and radial temperature detection system, coupled with end-effector visual acquisition, real-time pressure detection, and precise metering of gas and water production, enabling multi-parameter synchronous characterization of the entire hydrate dissociation process. The monitoring system can comprehensively capture the dynamic patterns of blockage structure evolution, temperature and pressure response, and product production, providing comprehensive data support for revealing the mechanism of synergistic dissociation through ultrasound and pressure reduction, and optimizing unblocking process parameters.

[0021] This invention can effectively improve the overall dissociation efficiency of pipeline hydrate solid blockage and reduce ineffective energy input. At the same time, through precise back pressure control and staged process design, it enhances the controllability and safety of the unblocking process. It has good engineering application value in scenarios such as deepwater oil and gas development, gas storage pipeline flow assurance, and emergency rapid removal of pipeline solid blockage. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the connection structure between the ultrasonic transducer assembly and the ultrasonic generator of the present invention; Figure 3 This is a schematic diagram of the end-visible flange assembly structure of the present invention; Figure 4 This is a schematic diagram of the data acquisition and analysis device of the present invention; Figure 5 This is a schematic diagram of the temperature detection section and the axial and radial arrangement of thermocouples in the high-pressure pipeline model of the present invention; Figure 6 A schematic diagram of the gas injection port structure for the high-pressure pipeline model of the present invention; Figure 7 This is a schematic diagram of the discharge port structure of the high-pressure pipeline model of the present invention; Figure 8 This is a schematic diagram of the ultrasonic transducer connection structure of the present invention; Explanation of markings in the diagram: 1. High-pressure gas cylinder; 2. Gas pressure reducing valve; 3. Flame arrester; 4. Shut-off valve; 5. Gas flow meter; 6. Safety valve; 7. Check valve; 8. Bracket; 9. Ball valve; 10. Thermocouple; 11. Circulation hose; 12. Rubber and plastic insulation cotton; 13. Constant temperature water bath; 14. Sealing ring; 15. High-speed camera; 16. Liquid flow meter; 17. Intermediate buffer container; 18. Liquid pump; 19. Liquid container; 20. Electronic balance; 21. Beaker; 22. Constant speed and constant pressure pump; 23. High-pressure container; 24. Constant temperature heating mantle; 25. Automatic back pressure valve; 26. Gas-liquid separator; 27. Gas drying tube; 28. Burner; 29. ​​Ignition device; 3 0. Pressure sensor; 31. End flange; 32. Circular clamping cap; 33. Transparent sight glass; 34. High-pressure pipeline model; 34a. Gas injection port; 34b. Pressure detection port; 34c. Forced exhaust port; 34d. Discharge port; 34e. Temperature detection port; 34f. Liquid injection port; 35. Segmented jacketed tube; 36. Liquid inlet at the bottom of the jacketed tube; 37. External clamp-on ultrasonic transducer; 38. Bolt; 39. Nut; 40. Exhaust end cap; 41. Lead wire hole; 42. Arc-shaped coupling head; 43. Liquid outlet at the top of the jacketed tube; 44. Transmission cable; 45. Ultrasonic generator; 46. Data acquisition and analysis device; 47. Temperature detection section. Detailed Implementation

[0023] To better understand the purpose, structure, and function of this invention, the ultrasonic and pressure-reducing synergistic dissociation device and method for hydrate blockage in pipelines will be described in further detail below with reference to the accompanying drawings.

[0024] like Figure 1-8 As shown, the present invention provides an ultrasonic and pressure reduction synergistic device for the dissociation of solid blockages caused by hydrates in pipelines, comprising a high-pressure pipeline model 34, a gas injection device, a liquid injection device, a constant temperature control device, an ultrasonic loading device, an automatic back pressure control device, a gas-liquid separation device 26, a gas disposal device, a liquid recovery measurement device, a visual acquisition device, and a data acquisition and analysis device 46. The high-pressure pipeline model 34 is provided with a gas injection port 34a, a liquid injection port 34f, a discharge port 34d, a forced discharge port 34c, a pressure detection port 34b, and a temperature detection port 34e. At least one end of the high-pressure pipeline model 34 is provided with an end visible flange assembly. The gas injection device is connected to the gas injection port 34a, the liquid injection device is connected to the liquid injection port 34f, the discharge port 34d is connected to the gas-liquid separation device 26 via the automatic back pressure control device, the gas outlet of the gas-liquid separation device 26 is connected to the gas disposal device, and the liquid outlet of the gas-liquid separation device 26 is connected to the liquid recovery measuring device. The constant temperature control device is located on the outside of the high-pressure pipeline model 34 to maintain the high-pressure pipeline model 34 at a preset temperature. The ultrasonic loading device includes an ultrasonic generator 45 and multiple external clamp-on ultrasonic transducers 37. The multiple external clamp-on ultrasonic transducers 37 are arranged along the axial direction of the high-pressure pipeline model 34 and are electrically connected to the output end of the ultrasonic generator 45 through transmission cables 44. The visual acquisition device is positioned towards the end visual flange assembly. The pressure detection port 34b is connected to the pressure detection device, and the temperature detection port 34e is connected to the temperature detection device. The data acquisition and analysis device 46 is connected to the pressure detection device, the temperature detection device, the gas flow meter 5, the liquid flow meter 16, the liquid recovery measurement device, and the ultrasonic generator 45, respectively.

[0025] Combination Figure 1-8 As shown, the system includes a high-pressure pipeline model 34, a gas injection device, a liquid injection device, a constant temperature control device, an ultrasonic loading device, an automatic back pressure control device, a gas-liquid separation device 26, a gas disposal device, a liquid recovery measurement device, a visual acquisition device, and a data acquisition and analysis device 46. The high-pressure pipeline model 34 is fixedly supported on both sides by brackets 8 to simulate the entire process of hydrate formation, blockage, and dissociation within the pipeline. At least one end of the high-pressure pipeline model 34 is equipped with an end-visible flange assembly. The pipe wall of the high-pressure pipeline model 34 is equipped with a gas injection port 34a, a liquid injection port 34f, a discharge port 34d, a forced discharge port 34c, a pressure detection port 34b, and a temperature detection port 34e.

[0026] Combination Figure 6-8 As shown, the gas injection device is connected to the gas injection port 34a and is used to deliver experimental gas into the high-pressure pipeline model 34. The gas injection device includes a high-pressure gas cylinder 1, a gas pressure reducing valve 2, a flame arrester 3, a shut-off valve 4, and a gas flow meter 5 connected sequentially along the gas flow direction. The experimental gas in the high-pressure gas cylinder 1 is pressurized by the gas pressure reducing valve 2 and then enters the high-pressure pipeline model 34 through the gas injection port 34a. The gas injection device is also equipped with a safety valve 6 and a one-way valve 7 to improve the safety of the gas injection process and the unidirectional stability of the flow.

[0027] The liquid injection device is connected to the liquid injection port 34f and is used to deliver experimental liquid into the high-pressure pipeline model 34. The liquid injection device includes a liquid container 19, a liquid pump 18, an intermediate buffer container 17, and a liquid flow meter 16. The inlet of the liquid pump 18 is connected to the liquid container 19, and the outlet of the liquid pump 18 is connected to the inlet of the liquid flow meter 16 through the intermediate buffer container 17. The outlet of the liquid flow meter 16 is connected to the liquid injection port 34f. The intermediate buffer container 17 is used to reduce the instantaneous pulsation during the liquid delivery process and improve the stability of the liquid injection. The liquid flow meter 16 is used to record the flow parameters of the liquid injection.

[0028] An ultrasonic loading device is positioned on the outside of the high-pressure pipeline model 34 to apply non-invasive ultrasonic action to the inside of the pipeline. The ultrasonic loading device includes an ultrasonic generator 45 and multiple clamp-on ultrasonic transducers 37. The multiple clamp-on ultrasonic transducers 37 are arranged at intervals along the axial direction of the high-pressure pipeline model 34 and are electrically connected to the output end of the ultrasonic generator 45 via transmission cables 44.

[0029] like Figure 2 As shown, the externally clamped ultrasonic transducers 37 are arranged in pairs opposite each other to form an ultrasonic transducer group; in this embodiment, a total of four ultrasonic transducer groups are set, and the axial distance between two adjacent ultrasonic transducer groups is 250~300 mm. Each externally clamped ultrasonic transducer 37 includes an ultrasonic transducer body and an arc-shaped coupling head 42 set at the output end of the ultrasonic transducer body. The arc-shaped coupling head 42 is made of titanium alloy. The inner side of the arc-shaped coupling head 42 is provided with an arc-shaped coupling surface that matches the curvature of the outer wall of the high-pressure pipeline model 34. The arc-shaped coupling surface is attached to the outer wall surface of the high-pressure pipeline model 34. The two arc-shaped coupling heads 42 arranged opposite each other are clamped to the outer periphery of the high-pressure pipeline model 34 by bolts 38 and nuts 39 to ensure stable coupling transmission of ultrasonic vibration.

[0030] The external clamp-on ultrasonic transducer 37 has a lead hole 41 on its housing. A transmission cable 44 connects to the terminal of the external clamp-on ultrasonic transducer 37 via the lead hole 41, and the other end of the transmission cable 44 connects to the corresponding output channel of the ultrasonic generator 45. The ultrasonic generator 45 has multiple independent output channels, each connected to an external clamp-on ultrasonic transducer 37 at a different location, allowing the external clamp-on ultrasonic transducers 37 at different locations to start / stop independently and adjust their operating parameters independently. The operating parameters include at least one of operating frequency, output power, duty cycle, and operating time. An exhaust end cap 40 is provided at the top of the external clamp-on ultrasonic transducer 37 to assist in heat dissipation.

[0031] A constant temperature control device is installed on the outside of the high-pressure pipeline model 34 to maintain the high-pressure pipeline model 34 at a preset temperature. The constant temperature control device includes a constant temperature water bath 13, a circulating hose 11, a liquid flow meter 16, multiple segmented jacketed pipes 35, and an insulation layer; the multiple segmented jacketed pipes 35 are arranged at intervals along the axial direction of the high-pressure pipeline model 34, and the outside of the segmented jacketed pipes 35 is covered with an insulation layer, which is made of rubber and plastic insulation cotton 12 with a thickness of not less than 100 mm.

[0032] Each segmented jacketed tube 35 is equipped with a lower inlet 36 and an upper outlet 43. Adjacent segmented jacketed tubes 35 are connected in series via a circulation hose 11. The upper outlet 43 of the previous segmented jacketed tube 35 is connected to the lower inlet 36 of the next segmented jacketed tube 35 via the circulation hose 11, so that the constant temperature circulating liquid flows through each segmented jacketed tube 35 from bottom to top, ensuring a uniform temperature field inside the tube. A liquid flow meter 16 is installed between the constant temperature water bath 13 and the lower inlet 36 of the first segmented jacketed tube 35 to monitor the circulation flow rate of the constant temperature circulating liquid. Thermocouples 10 are installed at least at the lower inlet 36 of the first segmented jacketed tube 35 and the upper outlet 43 of the last segmented jacketed tube 35 to detect the inlet and outlet temperatures of the constant temperature circulating liquid. In this embodiment, the constant temperature circulating fluid is an aqueous solution of ethylene glycol.

[0033] Temperature detection port 34e is connected to a temperature detection device for collecting temperature distribution data inside the high-pressure pipeline model 34. The temperature detection device includes multiple temperature detection sections 47 spaced apart along the axial direction of the high-pressure pipeline model 34, with at least some sections 47 positioned between adjacent ultrasonic transducer groups. Each temperature detection section 47 is equipped with multiple thermocouples 10 with different insertion depths. The temperature-sensing ends of the thermocouples 10 are distributed radially along the high-pressure pipeline model 34 to obtain temperature information at different radial depths within the same section. In this embodiment, each temperature detection section 47 is equipped with six thermocouples 10, with insertion depths of 2 mm, 11 mm, 20 mm, 29 mm, 38 mm, and 47 mm, respectively. The axial spacing between adjacent temperature detection sections 47 is 250 mm.

[0034] The end-visible flange assembly includes an end flange 31, a circular clamping cap 32, a transparent sight glass 33, and a sealing ring 14. The end flange 31 connects to the end of the high-pressure pipeline model 34. The sealing ring 14 is positioned between the end flange 31 and the end of the high-pressure pipeline model 34 for high-pressure sealing of the end connection interface. The end flange 31 has a central observation hole communicating with the inner cavity of the high-pressure pipeline model 34. The transparent sight glass 33 covers the observation hole, and the circular clamping cap 32 presses and fixes the transparent sight glass 33 to the end flange 31. The end flange 31 has multiple connection holes circumferentially. The end of the high-pressure pipeline model 34 has corresponding through holes. Bolts 38 pass through the connection holes of the end flange 31 and the through holes at the end of the high-pressure pipeline model 34, and then engage with nuts 39 to lock the end flange 31 in place. The circular clamping cover 32 has multiple mounting holes along its circumference, and the end flange 31 has threaded holes corresponding to the mounting holes. The bolts 38 pass through the mounting holes of the circular clamping cover 32 and are screwed into the threaded holes of the end flange 31 to achieve the clamping and fixing of the transparent sight glass 33.

[0035] The discharge port 34d is connected to the gas-liquid separator 26 via an automatic back pressure control device. The automatic back pressure control device is used to regulate the pressure boundary and pressure reduction rate during the depressurization and dissociation process. The automatic back pressure control device includes an automatic back pressure valve 25, a constant speed and constant pressure pump 22, and a constant temperature heating jacket 24. The discharge port 34d of the high-pressure pipeline model 34 is connected to the inlet end of the automatic back pressure valve 25 via a connecting pipe. A pressure sensor 30 and a shut-off valve 4 are installed on the connecting pipe. The pressure detection port 34b is connected to a pressure detection device, which uses a pressure sensor 30 to detect the pressure value inside the high-pressure pipeline model 34 in real time.

[0036] A constant-speed, constant-pressure pump 22 is connected to the control terminal of an automatic back-pressure valve 25 to provide a set control pressure to the automatic back-pressure valve 25, and to regulate the back pressure and pressure reduction process by adjusting the control pressure. A high-pressure container 23 is installed on the pipeline between the constant-speed, constant-pressure pump 22 and the automatic back-pressure valve 25 to buffer pressure fluctuations and improve pressure control stability. A constant-temperature heating jacket 24 covers the outside of the automatic back-pressure valve 25 to maintain the automatic back-pressure valve 25 at a preset operating temperature, reducing the risk of low-temperature blockage or secondary hydrate formation at the valve body due to throttling and pressure reduction. In this embodiment, the preset operating temperature of the constant-temperature heating jacket 24 is 50°C.

[0037] The liquid outlet of the automatic back pressure valve 25 is connected to the gas-liquid separator 26, which is used to separate the gas-liquid mixture produced by dissociation. The gas outlet of the gas-liquid separator 26 is connected to the gas disposal device, and the liquid outlet of the gas-liquid separator 26 is connected to the liquid recovery and measuring device. The liquid recovery and measuring device includes a beaker 21 and an electronic balance 20. The beaker 21 receives the liquid separated by the gas-liquid separator 26, and the electronic balance 20 is used to weigh the mass of the liquid in the beaker 21 in real time, realizing online measurement of the water production.

[0038] The gas handling device includes a gas drying pipe 27, a gas flow meter 5, a shut-off valve 4, a flame arrester 3, a burner 28, and an igniter 29 connected sequentially along the gas flow direction. The gas inlet of the gas drying pipe 27 is connected to the gas outlet of the gas-liquid separator 26. The gas produced by the separation is dried by the gas drying pipe 27, and the gas production is measured by the gas flow meter 5. Finally, it is introduced into the burner 28, ignited by the igniter 29, and safely discharged. The flame arrester 3 is used to prevent flame backfire and improve operational safety.

[0039] The visual acquisition device is positioned with a transparent viewing mirror 33 facing the end visual flange assembly, and is used to acquire images of the evolution of the hydrate blockage structure inside the high-pressure pipeline model 34; in this embodiment, the visual acquisition device is a high-speed camera 15.

[0040] The data acquisition and analysis device 46 is connected to the pressure detection device, temperature detection device, gas flow meter 5, liquid flow meter 16, liquid recovery measurement device, visual acquisition device and ultrasonic generator 45 respectively, and is used to synchronously acquire and analyze the pressure, temperature, gas production, water production, ultrasonic working parameters and visual image information during the dissociation process.

[0041] The forced discharge port 34c is connected to a ball valve 9. After the experiment, opening the ball valve 9 can quickly discharge the experimental medium in the high-pressure pipeline model 34, which facilitates the depressurization, cleaning and preparation of the device for subsequent experiments.

[0042] Combination Figure 1-8 As shown, the process of dissociating solid hydrate blockages in pipelines using the above-mentioned device is as follows: S1. Generate a hydrate blockage system: Inject a preset amount of experimental liquid and experimental gas into the high-pressure pipeline model 34. Adjust the temperature of the high-pressure pipeline model 34 to a preset low temperature condition through a constant temperature control device. Let it stand until a stable hydrate blockage system is generated in the high-pressure pipeline model 34, and maintain the high-pressure pipeline model 34 at a preset temperature.

[0043] S2. Release free gas and stabilize the system: Before starting the depressurization and dissociation, release the free gas in the high-pressure pipeline model 34, so that the pressure in the high-pressure pipeline model 34 is 0.01~0.1 MPa higher than the hydrate phase equilibrium pressure under the corresponding operating condition; in this embodiment, the pressure after the free gas is released is 0.05 MPa higher than the hydrate phase equilibrium pressure under the corresponding operating condition; wait for the pressure and temperature in the high-pressure pipeline model 34 to return to a stable state and remain so for 25 minutes to eliminate the interference of free gas on the subsequent gas production measurement.

[0044] S3. Start pressure reduction and dissociation: Adjust the set back pressure of the automatic back pressure control device, open the shut-off valve 4 of the discharge port 34d, and start the pressure reduction and dissociation process so that the pressure in the high-pressure pipeline model 34 decreases uniformly at the preset pressure reduction rate; in this embodiment, the set back pressure is 0.3~0.8 MPa, preferably 0.5 MPa; the preset pressure reduction rate is 0.05~0.15 MPa / min, preferably 0.08 MPa / min.

[0045] S4. Divide the dissociation stage: Taking the first time the pressure in the high-pressure pipeline model 34 reaches the set back pressure as the stage turning point, the entire dissociation process is divided into the main dissociation stage and the back pressure holding dissociation stage; the process of the pressure dropping from the initial value to the set back pressure is the main dissociation stage, and the process of the pressure being maintained at the set back pressure is the back pressure holding dissociation stage.

[0046] S5. Applying ultrasonic synergistic effect: According to the preset dissociation strategy, the external clamp-on ultrasonic transducer 37 is controlled by the ultrasonic generator 45 to apply ultrasonic effect before pressure reduction, during the main body dissociation stage and / or during the back pressure holding dissociation stage.

[0047] Pre-defined dissociation strategies include one or more of the following: pre-ultrasound mode, simultaneous depressurization ultrasound mode, staged depressurization ultrasound mode, and post-ultrasound mode, wherein: The pre-ultrasonic mode involves applying ultrasonic action before initiating depressurization to pre-disrupt the overall structure of hydrate blockage; The synchronous depressurization ultrasonic mode involves continuously applying ultrasonic action from the start of depressurization until the dissociation process ends. The phased depressurization ultrasonic mode applies ultrasonic action only during the main body dissociation stage, and stops ultrasonic action when the pressure first reaches the set back pressure. The later ultrasonic mode involves applying ultrasound during the back pressure-maintained dissociation phase to enhance the dissociation of residual hydrates at the end of the phase.

[0048] This embodiment adopts a staged pressure reduction ultrasonic mode. The operating frequency of the external clamp-on ultrasonic transducer 37 is preferably 33kHz, and the output power is preferably 800W.

[0049] S6. End of dissociation: The pressure, temperature, gas production, water production and ultrasonic working parameters during the dissociation process are recorded in real time by the data acquisition and analysis device 46. When the pressure and temperature in the high-pressure pipeline model 34 tend to stabilize and the gas production rate meets the preset stability condition, the dissociation process is determined to be over. In this embodiment, the preset stability condition is that the gas production rate is less than 0.1 L / h.

[0050] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A device for the coordinated dissociation of hydrate blockage in pipes using ultrasound and pressure reduction, characterized in that, It includes a high-pressure pipeline model (34), a gas injection device, a liquid injection device, a constant temperature control device, an ultrasonic loading device, an automatic back pressure control device, a gas-liquid separation device (26), a gas disposal device, a liquid recovery measurement device, a visual acquisition device, and a data acquisition and analysis device (46). The high-pressure pipeline model (34) is provided with a gas injection port (34a), a liquid injection port (34f), a discharge port (34d), a forced discharge port (34c), a pressure detection port (34b) and a temperature detection port (34e), and at least one end of the high-pressure pipeline model (34) is provided with an end visible flange assembly. The gas injection device is connected to the gas injection port (34a), the liquid injection device is connected to the liquid injection port (34f), the discharge port (34d) is connected to the gas-liquid separation device (26) via the automatic back pressure control device, the gas outlet of the gas-liquid separation device (26) is connected to the gas disposal device, and the liquid outlet of the gas-liquid separation device (26) is connected to the liquid recovery measurement device. The constant temperature control device is set on the outside of the high pressure pipeline model (34) to maintain the high pressure pipeline model (34) at a preset temperature. The ultrasonic loading device includes an ultrasonic generator (45) and multiple external clamp ultrasonic transducers (37). The multiple external clamp ultrasonic transducers (37) are arranged along the axial direction of the high pressure pipeline model (34) and are electrically connected to the output end of the ultrasonic generator (45) through transmission cables (44). The visual acquisition device is positioned toward the end visual flange assembly. The pressure detection port (34b) is connected to the pressure detection device, and the temperature detection port (34e) is connected to the temperature detection device. The data acquisition and analysis device (46) is connected to the pressure detection device, the temperature detection device, the gas flow meter (5), the liquid flow meter (16), the liquid recovery measurement device, and the ultrasonic generator (45) respectively.

2. The ultrasonic and pressure-reducing synergistic dissociation device for pipe hydrate blockage according to claim 1, characterized in that, The external clamp-on ultrasonic transducers (37) are arranged in pairs to form an ultrasonic transducer group; each external clamp-on ultrasonic transducer (37) includes an ultrasonic transducer body and an arc-shaped coupling head (42) disposed at its output end. The arc-shaped coupling head (42) is made of titanium alloy material; the inner side of the arc-shaped coupling head (42) is provided with an arc-shaped coupling surface that matches the curvature of the outer wall of the high-pressure pipeline model (34). The arc-shaped coupling surface is attached to the outer wall of the high-pressure pipeline model (34); the two arc-shaped coupling heads (42) arranged opposite to each other are clamped to the outer periphery of the high-pressure pipeline model (34) by bolts (38).

3. The ultrasonic and pressure-reducing synergistic dissociation device for pipe hydrate blockage according to claim 2, characterized in that, The temperature detection device includes multiple temperature detection sections (47) spaced apart along the axial direction of the high-pressure pipeline model (34). Each temperature detection section (47) is provided with multiple thermocouples (10) with different insertion depths. The temperature measuring ends of the multiple thermocouples (10) are distributed along the radial direction of the high-pressure pipeline model (34). At least a portion of the temperature detection sections (47) are located between adjacent ultrasonic transducer groups.

4. The ultrasonic and pressure-reducing synergistic dissociation device for pipe hydrate blockage according to claim 1, characterized in that, The end visible flange assembly includes an end flange (31), a circular clamping cap (32), a transparent sight glass (33), and a sealing ring (14); the end flange (31) is connected to the end of the high-pressure pipeline model (34), and the sealing ring (14) is disposed between the end flange (31) and the end of the high-pressure pipeline model (34); the end flange (31) has an observation through hole in the center that communicates with the inner cavity of the high-pressure pipeline model (34), the transparent sight glass (33) covers the observation through hole, and the circular clamping cap (32) presses the transparent sight glass (33) against the end flange (31).

5. The ultrasonic and pressure-reducing synergistic dissociation device for pipe hydrate blockage according to claim 2, characterized in that, The housing of the external clamp-on ultrasonic transducer (37) is provided with a lead hole (41). The transmission cable (44) is connected to the terminal of the external clamp-on ultrasonic transducer (37) through the lead hole (41). The other end of the transmission cable (44) is connected to the ultrasonic generator (45). The ultrasonic generator (45) has multiple independent output channels. Each independent output channel is connected to the external clamp-on ultrasonic transducer (37) at different positions, so that the external clamp-on ultrasonic transducer (37) at different positions can be started and stopped independently and the working parameters can be adjusted independently. The working parameters include at least one of working frequency, output power, duty cycle and working time.

6. The ultrasonic and pressure-reducing synergistic dissociation device for pipe hydrate blockage according to claim 1, characterized in that, The constant temperature control device includes a constant temperature water bath (13), a circulating hose (11), a liquid flow meter (16), multiple segmented jacketed pipes (35), and an insulation layer; the multiple segmented jacketed pipes (35) are arranged axially and spaced along the high-pressure pipeline model (34), and the insulation layer is wrapped around the outside of each segmented jacketed pipe (35); each segmented jacketed pipe (35) is provided with a liquid inlet (36) at the bottom of the jacketed pipe and a liquid outlet (43) at the top of the jacketed pipe, and adjacent segmented jacketed pipes (35) The constant temperature circulating liquid is connected in series through the circulating hose (11) so that it flows through each segment jacketed tube (35) in a bottom-up manner; the liquid flow meter (16) is set between the constant temperature water bath (13) and the lower liquid inlet (36) of the first segment jacketed tube (35), and thermocouples (10) are respectively set at the lower liquid inlet (36) of the first segment jacketed tube (35) and the upper liquid outlet (43) of the last segment jacketed tube (35).

7. The ultrasonic and pressure-reducing synergistic dissociation device for pipe hydrate blockage according to claim 1, characterized in that, The automatic back pressure control device includes an automatic back pressure valve (25), a constant speed and constant pressure pump (22), and a constant temperature heating jacket (24); the discharge port (34d) of the high pressure pipeline model (34) is connected to the automatic back pressure valve (25) through a connecting pipeline, and a pressure sensor (30) and a shut-off valve (4) are provided on the connecting pipeline; the constant speed and constant pressure pump (22) is connected to the control end of the automatic back pressure valve (25), and a high pressure container (23) is provided on the pipeline between the constant speed and constant pressure pump (22) and the automatic back pressure valve (25); the constant temperature heating jacket (24) covers the outside of the automatic back pressure valve (25).

8. The ultrasonic and pressure-reducing synergistic dissociation device for pipe hydrate blockage according to claim 1, characterized in that, The gas treatment device includes a gas drying pipe (27), a gas flow meter (5), a shut-off valve (4), a flame arrester (3), a burner (28), and an igniter (29) connected in sequence along the gas flow direction. The gas inlet of the gas drying pipe (27) is connected to the gas outlet of the gas-liquid separation device (26).

9. A method for dissolving solid blockages of hydrated pipes using the apparatus described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. A hydrate blockage system is generated in the high-pressure pipeline model (34), and the high-pressure pipeline model (34) is maintained at a preset temperature by a constant temperature control device. S2. Release the free gas in the high-pressure pipeline model (34) before depressurization and dissociation, and restore the pressure and temperature in the high-pressure pipeline model (34) to a stable state; S3. Adjust the set back pressure of the automatic back pressure control device and start the pressure reduction dissociation so that the pressure inside the high pressure pipeline model (34) decreases according to the preset pressure reduction rate. S4. Taking the first time the pressure inside the high-pressure pipeline model (34) reaches the set back pressure as the stage turning point, the dissociation process is divided into the main dissociation stage and the back pressure holding dissociation stage. S5. According to the preset dissociation strategy, the external clamp ultrasonic transducer (37) is controlled by the ultrasonic generator (45) to apply ultrasonic action before pressure reduction, during the main body dissociation stage and / or during the back pressure holding dissociation stage. S6. The pressure, temperature, gas production, water production and ultrasonic working parameters during the dissociation process are recorded by the data acquisition and analysis device (46), and the dissociation process ends after the state in the high-pressure pipeline model (34) meets the preset stability conditions.

10. The method for dissociating solid blockages of pipeline hydrates according to claim 9, characterized in that, In step S2, the pressure after the free gas is released is 0.01~0.1 MPa higher than the hydrate phase equilibrium pressure under the corresponding operating conditions; in step S3, the set back pressure is 0.3~0.8 MPa, and the preset depressurization rate is 0.05~0.15 MPa / min; in step S5, the preset dissociation strategy includes one or more of the following: pre-ultrasonic mode, synchronous depressurization ultrasonic mode, staged depressurization ultrasonic mode, and late ultrasonic mode. The pre-ultrasonic mode applies ultrasonic action before starting depressurization; the synchronous depressurization ultrasonic mode applies ultrasonic action continuously from the start of depressurization until the dissociation process ends; the staged depressurization ultrasonic mode applies ultrasonic action only during the main dissociation stage and stops ultrasonic action when the pressure first reaches the set back pressure; and the late ultrasonic mode applies ultrasonic action during the dissociation stage while maintaining the back pressure.

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