Experimental device for research on dense two-phase flow of oil wax particles

Abstract

The invention provides an experimental device for oil wax particle dense two-phase flow research, and relates to the technical field of fluid dynamics research. The experimental device comprises a circulating pipeline, a liquid storage tank, a detachable flow observation system, a first temperature control water bath, a second temperature control water bath, a peristaltic pump and a data monitoring system, the circulating pipeline is communicated with the liquid storage tank to form a closed loop; a heat exchange pipe is spirally wound on the outer wall of the circulating pipeline and is communicated with the first temperature control water bath; a heat exchange interlayer is arranged on the outer wall of the liquid storage tank and is communicated with the second temperature control water bath; the detachable flow observation system comprises at least one section of transparent observation tube serving as a test section and a high-speed camera; the data monitoring system comprises a pressure meter and a thermometer which are arranged at the two ends of the transparent observation pipe, and a flow meter arranged on the circulating pipeline. According to the experimental device, high-fidelity experimental characterization of the oil wax dense two-phase flow process can be achieved, and therefore a reliable verification basis is provided for a simulation calculation model.

Description

Technical Field

[0001] This application relates to the field of fluid dynamics research technology, and in particular to an experimental apparatus for studying dense two-phase flow of oil and wax particles. Background Technology

[0002] With the increasing prevalence of ambient temperature storage in crude oil tanks, the mixing and transportation of high-concentration, large-diameter wax particles in the bottom sludge of the tanks has become a key challenge to ensure the safe operation of pipelines.

[0003] In existing technologies, dense two-phase flow is mainly studied using two methods: macroscopic experiments and numerical simulations. In macroscopic experiments, water is typically used as the carrier and particles such as sand as the solid phase to construct a non-viscous solid-liquid two-phase flow loop, and particle motion is observed through a transparent pipe. In numerical simulations, a coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model is often used to analyze momentum transfer and particle distribution between the solid and liquid phases. The results of macroscopic experiments provide strong data support for the verification and correction of numerical simulation models. The development and advancement of numerical models greatly cover extreme and hazardous operating conditions, further ensuring the safety and reliability of two-phase flow.

[0004] However, existing methods are difficult to accurately reflect the dense flow characteristics of high-concentration wax particles in oil-based non-Newtonian fluids. The deposition process is mostly analyzed qualitatively, lacking quantitative characterization methods. The experimental data is out of touch with actual industrial conditions, which also limits its application value in simulation model verification. Summary of the Invention

[0005] This application provides an experimental apparatus for studying the dense two-phase flow of oil and wax particles. Through independent temperature control, visual observation, and simultaneous acquisition of multiple parameters, it achieves high-fidelity experimental characterization of the dense two-phase flow process of oil and wax, providing a reliable verification basis for simulation calculation models.

[0006] In a first aspect, this application provides an experimental apparatus for studying the dense two-phase flow of oil and wax particles. The experimental apparatus includes: a circulation pipeline, a storage tank, a detachable flow observation system, a first temperature-controlled water bath, a second temperature-controlled water bath, a peristaltic pump, and a data monitoring system.

[0007] The circulation pipeline is connected to the storage tank to form a closed loop, which is used for the circulation of the dense two-phase slurry formed by the mixing of oil and wax particles with oil.

[0008] The outer wall of the circulation pipe is spirally wound with heat exchange tubes, which are connected to the first temperature-controlled water bath to regulate the temperature of the circulation pipe.

[0009] The outer wall of the storage tank is equipped with a heat exchange jacket, which is connected to the second temperature-controlled water bath to regulate the temperature inside the storage tank.

[0010] The detachable flow observation system includes at least one transparent observation tube as a test section and a camera. The transparent observation tube is connected to the circulation pipe via a detachable connector. The inner diameter of the transparent observation tube is the same as that of the circulation pipe. The camera is aimed at the transparent observation tube to capture the flow state of particles in the slurry.

[0011] The peristaltic pump is connected to the circulation pipeline and is used to drive the slurry to circulate in a closed loop;

[0012] The data monitoring system includes pressure gauges and thermometers installed at both ends of the transparent observation tube, as well as flow meters installed on the circulation pipeline, for synchronously monitoring the pressure drop, temperature and flow rate of the slurry in the transparent observation tube;

[0013] Real-time monitoring of pressure drop, temperature, and flow rate in transparent observation tubes is used for high-fidelity characterization of the thickness and spatial distribution of viscous sediments.

[0014] In one possible design, the storage tank is equipped with a stirring component to thoroughly mix the oil and wax particles with the oil before the experiment begins, so as to form a uniform, dense two-phase slurry.

[0015] In one possible design, a pressure purging line is also connected to the circulation pipeline for purging and drying the inside of the circulation pipeline with compressed gas after the experiment.

[0016] In one possible design, the transparent observation tube is made of glass fiber, quartz, or a transparent polymer composite material, and has oil resistance, temperature resistance, and pressure resistance.

[0017] In one possible design, the camera has a frame rate of no less than 1000 frames per second to capture the transient motion trajectory, sedimentation process, and aggregation behavior of oil and wax particles in the slurry.

[0018] In one possible design, the flow meter is a mass flow meter, suitable for measuring the flow rate of non-conductive oil-based slurries.

[0019] In one possible design, both the first and second temperature-controlled water baths are equipped with independent temperature control systems to set and maintain the temperatures of the circulation pipeline and the storage tank, respectively.

[0020] In one possible design, the detachable connector is a quick-release clamp type or a flange type, which facilitates the quick disassembly and replacement of the transparent observation tube.

[0021] In one possible design, the data monitoring system also includes a data acquisition module and a host computer, used to collect, store and display pressure drop, temperature, flow rate and high-speed camera image data in real time, and to achieve time synchronization of multi-source data.

[0022] In one possible design, the transparent observation tube is located on a horizontal straight section of the circulation pipeline, and the upstream inlet end of the transparent observation tube is farther than a preset distance from the outlet of the peristaltic pump and the nearest upstream pipe bend.

[0023] Based on the implementation methods provided in the above aspects, this application can be further combined to provide more implementation methods.

[0024] This application provides an experimental setup for studying the dense two-phase flow of oil and wax particles. A first temperature-controlled water bath, via a heat exchange tube spirally wound around the outer wall of a circulating pipe, achieves precise temperature control of the slurry within the pipe. A second temperature-controlled water bath, through a heat exchange jacket on the outer wall of a storage tank, independently regulates the temperature within the storage tank. This allows for the simulation of complex thermal boundary conditions in industrial scenarios (such as ambient temperature storage and low-temperature transport), ensuring that experimental results more closely resemble actual working conditions and improving the accuracy of simulation model verification. A transparent observation tube is connected to the circulating pipe via quick-release clamps or flange joints, facilitating rapid disassembly and replacement. A camera aimed at the transparent observation tube can capture the transient motion trajectory, sedimentation process, and aggregation behavior of wax particles in the slurry at a high frame rate. This not only improves experimental efficiency but also provides users with clear and stable visual data, contributing to a deeper understanding of the microscopic mechanisms involved in the mixing and transport of dense, viscous particles with oil flow. A peristaltic pump, as a power source, overcomes the high viscosity of oil and wax slurries, providing a stable and controllable flow output. Compared to traditional centrifugal or gear pumps, peristaltic pumps have the advantages of low shear force and small pulsation, avoiding damage to the structure of oil and wax particles and ensuring flow stability during the experiment. Pressure gauges and thermometers are respectively installed at both ends of a transparent observation tube to monitor pressure drop and temperature changes in the test section in real time. A flow meter is installed on the circulation pipeline to synchronously record the mass flow rate of the circulation pipeline. All sensor signals are synchronously acquired, stored, and displayed through a data monitoring system, constructing a multi-physics database under a unified spatiotemporal reference, providing a reliable basis for subsequent data analysis and model verification. The entire experimental setup forms a closed loop, avoiding media leakage and environmental pollution, while ensuring the stability and repeatability of the experimental process. By precisely controlling the initial mixing uniformity, temperature field distribution, and flow parameters, consistent experimental conditions are ensured for each experiment, improving the reliability and comparability of the data. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] Figure 1 This is a schematic diagram of the structure of an experimental apparatus for studying dense two-phase flow of oil and wax particles, provided in an embodiment of this application.

[0028] Figure label:

[0029] 1-Circulation pipeline; 2-Storage tank; 3-First temperature-controlled water bath; 4-Second temperature-controlled water bath; 5-Peristaltic pump; 6-Transparent observation tube; 7-Camera; 8-Pressure gauge; 9-Thermometer; 10-Flow meter; 11-Pressure purging pipeline; 12-Host computer; 201-Stirring component. Detailed Implementation

[0030] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0031] In the embodiments of this application, the terms "first" and "second" are used to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that "first" and "second" do not necessarily imply difference. It should be noted that in the embodiments of this application, the words "exemplary" or "for example" are used to indicate that something is being used as an example, illustration, or description. Any embodiment or design scheme described as "exemplary" or "for example" in this application should not be construed as being better or more advantageous than other embodiments or design schemes. Specifically, the use of "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner. In the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more.

[0032] It should be noted that the phrase "at...time" in the embodiments of this application can refer to the instant at which a certain situation occurs, or to a period of time after the occurrence of a certain situation; the embodiments of this application do not specifically limit this. Furthermore, the experimental apparatus provided in the embodiments of this application for studying dense two-phase flow of oil and wax particles is merely an example; an experimental apparatus for studying dense two-phase flow of oil and wax particles may include more or fewer components.

[0033] With increasing demands for energy conservation and emission reduction, crude oil storage tanks generally adopt ambient temperature storage, leading to the continuous enrichment of waxy components in the bottom sediments, forming a mixture of high-concentration, large-particle-size oil and wax particles (i.e., tank bottom sludge). Mixing this sludge with light oil products and transporting it via pipelines has become an important method for resource utilization. However, this process involves the flow of a dense two-phase mixture composed of a high-viscosity, non-Newtonian oil-based continuous phase and high-solids-content, large-particle-size wax particles. Its rheological behavior is complex, easily triggering operational problems such as sedimentation, blockage, or sudden pressure drops, posing a serious challenge to the safe and stable operation of long-distance pipelines.

[0034] Current technologies primarily rely on two methods to study the characteristics of dense two-phase flow: macroscopic experiments and numerical simulations. In macroscopic experiments, a low-viscosity, non-viscous solid-liquid two-phase flow loop system is typically constructed using water as the continuous phase and sand or glass beads as the solid phase. Transparent straight pipe sections combined with high-speed cameras are then used to observe particle trajectories. In numerical simulations, coupled CFD-DEM models are commonly employed. By solving the liquid phase equations and particle motion equations, the momentum exchange between the solid and liquid phases, particle spatial distribution, and sedimentation evolution are analyzed.

[0035] However, the above methods have significant limitations. On the one hand, water-based systems cannot simulate the non-Newtonian rheological properties of oils and the oil-wax interfacial interactions. On the other hand, existing experimental setups generally lack the ability to simultaneously and accurately monitor local pressure drop, temperature field, and flow rate in the test section, and it is difficult to achieve independent temperature control in the storage and transportation stages. Therefore, existing technologies cannot realistically reproduce the complex flow behavior of dense two-phase flow of oil and wax in industrial scenarios, and the obtained experimental data is seriously out of sync with actual working conditions, which restricts the development and verification of high-fidelity simulation models.

[0036] Based on this, this application proposes an experimental apparatus for studying the dense two-phase flow of oil and wax particles, applicable to the field of fluid dynamics research, aiming to solve the aforementioned technical problems of the prior art. A closed-loop system is constructed, integrating a circulation pipeline, a storage tank, a detachable flow observation system, a first temperature-controlled water bath, a second temperature-controlled water bath, a peristaltic pump, and a data monitoring system. The circulation pipeline and the storage tank achieve precise temperature control in separate temperature zones through independent temperature-controlled water baths. The detachable flow observation system includes at least one transparent observation tube with an inner diameter matching the main pipe and a camera, supporting the visual capture of transient particle motion behavior. The data monitoring system is equipped with pressure gauges and thermometers at both ends of the transparent observation tube and a flow meter on the circulation pipeline, enabling simultaneous and accurate acquisition of pressure drop, temperature, and system flow rate in the test section. Through the above design, this experimental device can realistically simulate the dense flow process of oil and wax particles in non-Newtonian oil-based slurry, obtain high spatiotemporal resolution multiphysics experimental data, and provide a high-fidelity and repeatable experimental verification basis for high-performance simulation calculation models such as Computational Fluid Dynamics-Dense Discrete Phase Model (CFD-DDPM), thereby supporting the safety analysis and optimization design of pipeline blending and transportation processes.

[0037] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0038] Figure 1 This is a schematic diagram of an experimental apparatus for studying dense two-phase flow of oil and wax particles, provided as an embodiment of this application. Figure 1 As shown, the experimental setup includes: a circulation pipeline 1, a liquid storage tank 2, a detachable flow observation system, a first temperature-controlled water bath 3, a second temperature-controlled water bath 4, a peristaltic pump 5, and a data monitoring system.

[0039] The circulation pipeline 1 is connected to the storage tank 2 to form a closed loop for the circulation of a dense two-phase slurry formed by the mixing of oil and wax particles with oil.

[0040] The outer wall of the circulation pipe 1 is spirally wound with a heat exchange tube, which is connected to the first temperature-controlled water bath 3 and is used to regulate the temperature of the circulation pipe 1.

[0041] The outer wall of the liquid storage tank 2 is provided with a heat exchange jacket, which is connected to the second temperature-controlled water bath 4 to regulate the temperature inside the liquid storage tank 2.

[0042] The detachable flow observation system includes at least one transparent observation tube 6 as a test section and a camera 7. The transparent observation tube 6 is connected to the circulation pipe 1 via a detachable connector. The inner diameter of the transparent observation tube 6 is the same as that of the circulation pipe 1. The camera 7 is aimed at the transparent observation tube 6 to capture the flow state of particles in the slurry.

[0043] The peristaltic pump 5 is connected to the circulation pipe 1 and is used to drive the slurry to circulate in a closed loop.

[0044] The data monitoring system includes a pressure gauge 8 and a thermometer 9 installed at both ends of the transparent observation tube 6, and a flow meter 10 installed on the circulation pipe 1, for synchronously monitoring the pressure drop, temperature and flow rate of the slurry in the transparent observation tube 6.

[0045] Real-time monitoring of pressure drop, temperature, and flow rate in transparent observation tube 6 is used to quantitatively characterize the thickness and spatial distribution of viscous deposits.

[0046] Specifically, such as Figure 1 As shown, the experimental device as a whole constitutes a closed-loop circulation system, mainly including: circulation pipeline 1, liquid storage tank 2, detachable flow observation system, first temperature-controlled water bath 3, second temperature-controlled water bath 4, peristaltic pump 5, and data monitoring system.

[0047] The circulation pipeline 1 and the storage tank 2 are interconnected by pipelines to form a closed circulation loop, which is used to achieve continuous circulation of a high-concentration, non-Newtonian dense two-phase slurry formed by the mixture of oil and wax particles and light oil. This closed loop avoids media leakage and environmental pollution, while ensuring the stability and repeatability of the experimental process.

[0048] To precisely control the experimental temperature field, a heat exchange tube is spirally wound along the axial direction on the outer wall of the circulation pipe 1. The two ends of the heat exchange tube are connected to the outlet and inlet of the first temperature-controlled water bath 3, respectively, forming an independent temperature control loop. By adjusting the set temperature of the first temperature-controlled water bath 3, the slurry in the circulation pipe 1 can be heated or cooled, thereby simulating the heat exchange conditions of the pipe wall under different transport environments.

[0049] Correspondingly, the outer wall of the storage tank 2 is provided with an annular heat exchange jacket, which is connected to the second temperature-controlled water bath 4 to form another independent temperature control unit. The temperature of the slurry inside the storage tank 2 can be individually adjusted through the second temperature-controlled water bath 4, so that it can maintain the same or different temperature state as the circulation pipeline 1, so as to realistically reproduce typical working conditions such as normal temperature storage in storage tanks and low temperature transportation in pipelines in industrial environments.

[0050] The detachable flow observation system is the core observation module of this device, comprising at least one transparent observation tube 6 serving as a test section and a camera 7. The transparent observation tube 6 can be connected to a designated location in the circulation pipe 1 via a quick-connect detachable joint (such as a clamp or flange). Its inner diameter is identical to that of the circulation pipe 1 to ensure no abrupt changes in the flow path and no additional local resistance, thus guaranteeing the authenticity of the flow state. The camera 7 is positioned directly opposite the transparent observation tube 6 to capture in real-time the movement trajectory, sedimentation behavior, aggregation / dispersion dynamics, and other micro-flow characteristics of the oil and wax particles in the slurry.

[0051] A peristaltic pump 5 is connected in series in the circulation pipeline 1, serving as a power source to drive the dense two-phase slurry to circulate stably in a closed loop. Due to the high viscosity and solid phase content of the oil and wax slurry, the peristaltic pump effectively avoids shear damage to the particle structure while providing a stable and controllable flow output.

[0052] The data monitoring system is used to achieve synchronous acquisition and monitoring of multiple physical quantities. Specifically, it includes a pressure gauge 8 and a thermometer 9 installed at both ends of the transparent observation tube 6 to accurately measure the pressure drop and temperature difference in the test section. The data monitoring system also includes a flow meter 10 (preferably a mass flow meter) installed on the circulation pipe 1 to acquire the system flow rate in real time. All the above sensor signals are connected to the data acquisition system, which can synchronously record changes in pressure drop, temperature, and flow rate over time, providing high-precision experimental data for subsequent analysis of particle concentration distribution, flow resistance characteristics, and model verification.

[0053] The experimental setup provided in this embodiment is based on a closed-loop circulating flow platform. It can achieve high-fidelity experimental simulation of the dense two-phase flow behavior of oil and wax particles in a non-Newtonian oil-based medium by precisely controlling the slurry properties, flow conditions, and thermal boundary conditions. Its working principle includes the following key steps. First, in the experimental preparation stage, the entire loop system is cleaned and calibrated. Residues inside the pipes are removed, and the initial readings of sensors such as flowmeter 10, thermometer 9, and pressure gauge 8 are reset to zero to eliminate system errors. Simultaneously, the first temperature-controlled water bath 3 and the second temperature-controlled water bath 4 are activated to stabilize the temperature of the circulating pipe 1 and the storage tank 2 at a preset temperature (e.g., 20 degrees Celsius), ensuring the experiment is conducted under constant temperature conditions.

[0054] Subsequently, oil and wax particles with a preset particle size distribution are weighed according to the target solid phase mass concentration and added to the storage tank 2 along with the base oil. The stirring component (such as a stirring motor) in the storage tank 2 is started, and the mixture is thoroughly mixed at a speed of 500 revolutions per minute (r / min) to form a uniform, stable, and dense two-phase slurry. This stirring process ensures the uniformity of the initial solid phase distribution and avoids distortion of the flow state due to sedimentation or agglomeration.

[0055] Next, the peristaltic pump 5 is started, driving the mixed slurry from the storage tank 2 into the circulation pipe 1, forming a closed-loop flow. By adjusting the speed of the peristaltic pump 5, the average flow rate of the slurry can be precisely controlled, thereby simulating different conveying conditions (such as low-flow-rate sedimentation zones and high-flow-rate suspension conveying zones). Because the peristaltic pump 5 has the advantages of low pulsation, low shear force, and resistance to highly viscous solid media, it can stably convey high-concentration oil and wax slurry without damaging the particle structure.

[0056] During the flow process, pressure gauges 8 and thermometers 9 located at both ends of the transparent observation tube 6 collect real-time pressure drop and temperature data of the test section, while flow meter 10 on the circulation pipe 1 records the mass flow rate simultaneously. Meanwhile, a camera is aimed at the transparent observation tube 6 to continuously capture the motion trajectory, settling velocity, aggregation morphology, and local flow field structure of the oil and wax particles. All sensor signals can be synchronously acquired, stored, and displayed through a data monitoring system, constructing a multi-physics coupled experimental database.

[0057] Finally, by comparing the pressure drop characteristics, particle distribution behavior, and flow stability under different solid mass concentrations and average flow velocities, the transport performance of dense two-phase flow of oil and wax can be quantitatively analyzed, and a high-precision verification basis can be provided for numerical models such as CFD-DDPM.

[0058] Therefore, this experimental setup, through the synergistic effect of independent temperature control, uniform mixing, visual observation, and simultaneous monitoring of multiple parameters, achieves high-fidelity experimental reproduction of industrial oil and wax blending and transportation conditions, overcoming the technical bottleneck that existing water-based or dilute-phase experimental systems cannot reflect the true dense two-phase flow characteristics of oil-based materials. In other words, the experimental setup in this embodiment, through two independent temperature controls, a visual testing section, high-fidelity sensors, and a closed-loop circulation design, enables a realistic, stable, and quantifiable experimental study of the dense two-phase flow behavior of oil and wax particles in non-Newtonian oil-based slurries, providing a reliable hardware platform for the development and verification of relevant numerical models (such as CFD-DDPM).

[0059] This embodiment provides an experimental setup for studying dense two-phase flow of oil and wax particles. A first temperature-controlled water bath 3, via a heat exchange tube spirally wound around the outer wall of a circulation pipe 1, achieves precise temperature control of the slurry within the pipe. A second temperature-controlled water bath 4, through a heat exchange jacket on the outer wall of a storage tank 2, independently regulates the temperature within the storage tank 2. This allows for the simulation of complex thermal boundary conditions in industrial scenarios (such as room temperature storage and low-temperature transport), ensuring that experimental results more closely approximate actual working conditions and improving the accuracy of simulation model verification.

[0060] The transparent observation tube 6 is connected to the circulation pipe 1 via quick-release clamps or flange joints, facilitating rapid disassembly and replacement. The camera 7, aimed at the transparent observation tube 6, can capture the transient motion trajectory, sedimentation process, and aggregation behavior of oil and wax particles in the slurry at a high frame rate. This not only improves experimental efficiency but also provides users with clear and stable visual data, contributing to a deeper understanding of the microscopic mechanisms involved in the mixing and transport of dense, viscous particles with oil flow.

[0061] As a power source, the peristaltic pump 5 can overcome the high viscosity characteristics of oil and wax slurry and provide a stable and controllable flow output. Compared with traditional centrifugal pumps or gear pumps, the peristaltic pump has the advantages of low shear force and small pulsation, which avoids damage to the structure of oil and wax particles and ensures the flow stability during the experiment.

[0062] Pressure gauge 8 and thermometer 9 are respectively installed at both ends of the transparent observation tube 6 to monitor the pressure drop and temperature changes of the test section in real time. Flow meter 10 (preferably a mass flow meter) is installed on the circulation pipe 1 to synchronously record the mass flow rate of the circulation pipe 1. All sensor signals are synchronously acquired, stored, and displayed through a data monitoring system, constructing a multiphysics database under a unified spatiotemporal reference, providing a reliable basis for subsequent data analysis and model verification.

[0063] The entire experimental setup forms a closed loop, preventing media leakage and environmental pollution, while ensuring the stability and repeatability of the experimental process. Precise control of initial mixing uniformity via a stirring component, temperature field distribution via a dual temperature control system, and flow parameters via a peristaltic pump 5 ensure consistent experimental conditions for each experiment, enhancing the reliability and comparability of the data.

[0064] This experimental setup can realistically reproduce the complex flow behavior of dense two-phase flow of oil and wax particles in industrial scenarios, and acquire multiphysics experimental data with high spatiotemporal resolution. This data provides a high-fidelity, repeatable experimental verification basis for high-performance simulation models such as CFD-DDPM, thereby supporting the safety analysis and optimization design of pipeline blending and transportation processes.

[0065] In one possible design, the storage tank 2 is equipped with a stirring component 201 to fully mix the oil wax particles with the oil before the experiment begins, so as to form a uniform, dense two-phase slurry.

[0066] Specifically, the storage tank 2 is equipped with a stirring component 201, which can be a mechanical stirring paddle, a magnetic stirring bar, or an impeller-type stirrer driven by a motor. It can be installed at the bottom, top, or side wall of the storage tank 2 and connected to an external speed-regulating motor.

[0067] Before the experiment, pre-weighed oil and wax particles and base oil were added to storage tank 2. The stirring unit 201 was started and stirred thoroughly at a set speed (e.g., 500 r / min) to ensure that the oil and wax particles were evenly dispersed in the oil, preventing sedimentation, agglomeration, or excessively high local concentrations. This resulted in a dense two-phase slurry with stable physical properties and uniform concentration distribution. This uniform mixing process is a key prerequisite for ensuring the reliability and repeatability of subsequent circulating flow experimental data, effectively simulating the initial state of the slurry during industrial blending and transportation.

[0068] In one possible design, a pressure purging line 11 is also connected to the circulation pipeline 1 for purging and drying the inside of the circulation pipeline 1 with compressed gas after the experiment.

[0069] Specifically, a pressure purging line 11 is also connected to the circulation pipeline 1. The pressure purging line 11 can be connected to the circulation pipeline 1 through a tee or quick-connect interface and is equipped with a control valve. Its inlet end can be connected to an external source of compressed air or inert gas (such as nitrogen).

[0070] After each experiment, the control valve is opened and compressed gas at a set pressure (e.g., 0.3 MPa to 0.6 MPa) is introduced to purge the inside of circulation pipe 1 under positive pressure, removing residual high-viscosity oil and wax slurry from the pipe walls and bends. Because oil-based slurries have strong adhesion and are not easily volatile, simply venting is insufficient for thorough cleaning. Purge with compressed gas not only effectively removes residues but also accelerates the drying of the pipe walls, preventing wax deposition and solidification or microbial growth. This significantly improves the maintainability and continuous experimental capability of the experimental setup, avoiding the impact of pipe blockage or cross-contamination on the accuracy of subsequent test results.

[0071] In one possible design, the transparent observation tube 6 is made of glass fiber, quartz, or a transparent polymer composite material, and has oil resistance, temperature resistance, and pressure resistance.

[0072] Specifically, the transparent observation tube 6 can be made of glass fiber reinforced composite material, fused silica, or high-performance transparent polymer composite material (such as optically transparent polyetheretherketone, modified polymethyl methacrylate, or transparent fluoropolymer). All of these materials undergo rigorous screening and possess excellent oil resistance (does not swell or crack after long-term immersion in crude oil, light oil, and waxy media), temperature resistance (maintains structural stability and optical transparency within a temperature range of 10°C to 80°C or even higher), and pressure resistance (can withstand typical operating pressures within the circulation pipeline 1, such as 0.1 MPa to 1.0 MPa, and resists the mechanical impact of oil and wax particles and the pulsation of the peristaltic pump 5).

[0073] Because the dense two-phase slurry of oil and wax has high viscosity, strong adhesion, and potential abrasiveness, ordinary transparent materials (such as ordinary glass or ordinary plastic) are prone to stress cracking, fogging, or chemical corrosion, leading to observation failure. However, the material selected in this embodiment not only ensures the long-term reliable operation of the transparent observation tube 6 under harsh conditions but also maintains high optical clarity, providing a clear imaging window for the camera 7, thereby guaranteeing the accurate capture and analysis of the flow behavior of oil and wax particles.

[0074] In one possible design, the camera 7 has a frame rate of no less than 1000 frames per second, used to capture the transient motion trajectory, sedimentation process and aggregation behavior of oil and wax particles in the slurry.

[0075] Specifically, the camera 7 has a frame rate of no less than 1000 frames per second (fps), preferably between 1000 fps and 10000 fps, for capturing the dynamic behavior of oil-wax particles in a high-viscosity oil-based slurry within the transparent observation tube 6 with high spatiotemporal resolution. Because the oil-wax particles move at high speeds in the pipe flow, and their settling, collision, aggregation, or resuspension processes often occur within millisecond timescales, using ordinary camera equipment (such as 30 fps to 200 fps) would result in insufficient temporal resolution to accurately record the transient trajectories and interaction details of the particles.

[0076] By configuring a high-speed camera with a frame rate of ≥1000fps and using a high-brightness backlight or side illumination system, the continuous displacement sequence of particles in a dense two-phase flow field can be clearly acquired. Then, image processing algorithms (such as particle tracking velocimetry) can be used to quantitatively analyze the velocity distribution, local concentration evolution, and aggregation dynamics of oil and wax particles. This high-frame-rate observation capability is a key experimental foundation for revealing the microscopic mechanism of dense two-phase flow in oil and wax and verifying the accuracy of particle phase behavior prediction in the CFD-DDPM simulation model.

[0077] In one possible design, the flow meter 10 is a mass flow meter suitable for measuring the flow rate of non-conductive oil-based slurries.

[0078] Specifically, flow meter 10 can be a mass flow meter, such as a Coriolis mass flow meter. Flow meter 10 is installed on the circulating pipeline 1 and is used to directly measure the mass flow rate of a dense two-phase slurry of oil and wax. Since the medium used in this experiment is an oil-based slurry (with crude oil or light oil as the continuous phase), it has the characteristics of non-conductivity, high viscosity, and the presence of solid particles. Traditional electromagnetic flow meters are unsuitable because they rely on the conductivity of the fluid, while turbine or ultrasonic volumetric flow meters are easily affected by viscosity changes, particle erosion, or bubble interference, leading to a significant increase in measurement error.

[0079] The Coriolis mass flow meter, based on the Coriolis effect, directly obtains the mass flow rate by detecting the phase difference caused by fluid flow in the vibrating tube. It does not rely on the fluid's conductivity, density, or velocity distribution, and exhibits good adaptability to non-Newtonian fluids and two-phase flows containing solids (especially under conditions of moderate solid concentration and controllable particle size). Furthermore, the mass flow meter can simultaneously output fluid density and temperature signals, facilitating subsequent calculation of volumetric flow rate or correction of physical property parameters.

[0080] Therefore, using a mass flow meter as the flow monitoring unit not only solves the problem of accurate metering of non-conductive oil-based slurry, but also improves the reliability and industrial applicability of the entire data monitoring system, providing high-precision input data for pressure drop and flow characteristic analysis and simulation model verification.

[0081] In one possible design, the first temperature-controlled water bath 3 and the second temperature-controlled water bath 4 are both equipped with independent temperature control systems, which are used to set and maintain the temperature of the circulation pipeline 1 and the storage tank 2 respectively.

[0082] Specifically, both the first temperature-controlled water bath 3 and the second temperature-controlled water bath 4 are equipped with independent temperature control systems, each including a temperature sensor, a heating / cooling unit, a circulating pump, and an intelligent controller, such as a proportional-integral-derivative (PID) temperature control system. The first temperature-controlled water bath 3 can precisely regulate the temperature of the heat transfer medium flowing through the heat exchange tubes on the outer wall of the circulating pipe 1 through its independent system, thereby setting and maintaining the delivery temperature of the slurry within the circulating pipe 1. The second temperature-controlled water bath 4 can adjust the temperature of the medium in the heat exchange jacket on the outer wall of the storage tank 2 through its dedicated control system, thereby independently controlling the storage temperature of the slurry inside the storage tank 2.

[0083] This dual-loop independent temperature control design is of great significance. In actual crude oil blending and transportation operations, the storage tank is often stationary at room temperature (e.g., 20°C to 25°C), while the pipeline may be at a lower temperature (e.g., 10°C to 15°C) due to underground burial or environmental heat dissipation, resulting in a significant temperature difference between the two. If a single water bath or linked temperature control is used, it is impossible to reproduce such non-uniform thermal boundary conditions, which will cause the slurry viscosity, wax precipitation behavior, and particle settling characteristics to deviate from reality. However, the experimental device in this embodiment uses two independent temperature control systems to flexibly set any combination of temperature differences (e.g., storage tank 2 temperature is 25°C, pipeline temperature is 15°C), accurately simulating the complex thermal environment of the industrial site, thereby ensuring the engineering representativeness of the experimental data and the reliability of the simulation model verification.

[0084] In addition, each temperature control system can dynamically maintain the preset temperature during the experiment, effectively suppressing temperature fluctuations caused by slurry circulation or environmental disturbances, thereby ensuring the stability of the flow conditions.

[0085] In one possible design, the detachable connector is a quick-release clamp connector or a flange connector, which facilitates the quick disassembly and replacement of the transparent observation tube 6.

[0086] Specifically, the transparent observation tube 6 is connected to the circulation pipe 1 via a detachable connector. This detachable connector can be a quick-connect clamp connector (such as a sanitary clamp connector) or a flange connector (such as a flat-face flange with a sealing gasket). The quick-connect clamp connector uses a clamp locking structure, combined with a silicone or fluororubber sealing ring, and only requires manual tightening of the clamp bolts to achieve a sealed connection, without welding or complex tools. The flange connector can use bolts to press the two flanges together to seal the gasket, suitable for high-pressure or frequently disassembled operating conditions.

[0087] This design significantly improves the convenience and efficiency of experimental operations. Before and after each experiment, users can disassemble, clean, replace, or repair the transparent observation tube 6 within minutes, effectively avoiding contamination of the observation window or pipe blockage caused by the solidification of high-viscosity oil and wax residue. Simultaneously, because the inner diameter of the flow channel at the joint is consistent with that of the circulation pipe 1 and the transparent observation tube 6, without steps or necking, the continuity of the flow field is ensured, avoiding additional flow disturbances caused by local abrupt changes, thus guaranteeing the authenticity of the flow state in the test section and the reliability of the measurement data. Furthermore, the two joint types can be flexibly selected according to the experimental pressure level, medium characteristics, and frequency of use, ensuring both sealing and safety while also considering practicality.

[0088] In one possible design, the data monitoring system also includes a data acquisition module and a host computer 12, which are used to collect, store and display pressure drop, temperature, flow rate and high-speed camera image data in real time, and realize time synchronization of multi-source data.

[0089] Specifically, the data monitoring system may also include a data acquisition module and a host computer 12. The data acquisition module consists of a multi-channel signal conditioning circuit, a high-precision analog-to-digital converter (ADC), and a synchronous triggering unit. It is electrically connected to the pressure gauge 8, thermometer 9, flow meter 10 on the circulation pipe 1, and camera 7 at both ends of the transparent observation tube 6, respectively, and is used to convert the analog or digital signals output by various sensors into a unified format digital data stream in real time. The host computer 12 is an industrial control computer or embedded industrial control computer, running dedicated data acquisition and analysis software to receive and process data from the data acquisition module.

[0090] During the experiment, the host computer 12 can collect, store, and synchronously display the pressure drop, temperature, mass flow rate, and high-speed camera image sequence of the test section in real time. To ensure strict alignment of multi-source heterogeneous data in the time dimension, a hardware-level time synchronization mechanism can be adopted. For example, the host computer 12 can issue a unified trigger signal to synchronously start the image acquisition of camera 7 and the data recording of each sensor, or use a high-precision real-time clock (RTC) or precision time protocol (PTP) to accurately timestamp each frame of image and each sensor sampling point. The time synchronization database constructed in this way can accurately correlate the movement behavior of oil and wax particles (such as sedimentation and agglomeration) with the corresponding instantaneous pressure drop, flow rate fluctuations, and other macroscopic parameters, providing a high-fidelity, high spatiotemporal resolution verification basis for subsequent CFD-DDPM and other simulation models.

[0091] In addition, the host computer 12 can also support data playback, trend analysis, anomaly alarm and remote monitoring functions, thereby significantly improving the level of automation of experiments and data utilization efficiency.

[0092] In one possible design, the transparent observation tube 6 is located on a horizontal straight section of the circulation pipe 1, and the upstream inlet end of the transparent observation tube 6 is farther than a preset distance from the outlet of the peristaltic pump 5 and the nearest upstream pipe bend.

[0093] Specifically, the transparent observation tube 6 can be installed on a horizontal straight section of the circulation pipe 1, and its upstream inlet end (i.e. the end where the slurry first enters the transparent observation tube 6) is more than a preset distance from the outlet of the peristaltic pump 5 and the nearest upstream pipe bend (such as a 90-degree bend or a diverter connecting the storage tank 2) in the circulation pipe 1.

[0094] This preset distance can be determined based on fully developed flow theory in fluid mechanics and experimental experience with dense two-phase flow. Specifically, it can be a preset value of not less than 10 times the inner diameter of the pipe, where the inner diameter of the pipe refers to the inner diameter of the circulation pipe 1. For example, when the inner diameter of the circulation pipe 1 is 25 mm, the upstream inlet end of the transparent observation tube 6 should be at least 250 mm away from the aforementioned disturbance source, and the preset distance can be 250 mm.

[0095] This arrangement has significant fluid dynamic implications. The peristaltic pump 5 generates periodic pressure pulsations and non-uniform velocity profiles during operation, while the upstream bend induces complex flow structures such as secondary flow, flow separation, and lateral particle migration. If the observation window is placed within these disturbance areas, the captured particle trajectories, local concentration distributions, and pressure drop data will be significantly interfered with, failing to accurately reflect the intrinsic characteristics of the dense two-phase flow of oil and wax under stable transport conditions. By ensuring that the transparent observation tube 6 is located on a straight pipe section sufficiently far from the disturbance source, the slurry can undergo flow adjustment before entering the test area, forming a fully developed flow field with stable velocity distribution and uniform particle suspension. This significantly improves the accuracy, repeatability, and engineering representativeness of high-speed camera observations and sensor measurements.

[0096] In addition, adopting a horizontal layout can avoid the rapid stratification of particles caused by gravity settlement in vertical pipe sections, which is more in line with the actual working conditions of horizontal buried oil pipelines in industry, making the experimental results more valuable for application.

[0097] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An experimental apparatus for studying dense two-phase flow of oil and wax particles, characterized in that, include: The system includes a circulation pipeline, a storage tank, a detachable flow observation system, a first temperature-controlled water bath, a second temperature-controlled water bath, a peristaltic pump, and a data monitoring system. The circulation pipeline is connected to the storage tank to form a closed loop for the circulation of a dense two-phase slurry formed by mixing oil and wax particles with oil. The outer wall of the circulation pipe is spirally wound with a heat exchange tube, which is connected to the first temperature-controlled water bath and is used to regulate the temperature of the circulation pipe. The outer wall of the liquid storage tank is provided with a heat exchange jacket, which is connected to the second temperature-controlled water bath and is used to regulate the temperature inside the liquid storage tank. The detachable flow observation system includes at least one transparent observation tube as a test section and a camera. The transparent observation tube is connected to the circulation pipe via a detachable connector. The inner diameter of the transparent observation tube is the same as that of the circulation pipe. The camera is aimed at the transparent observation tube to capture the flow state of particles in the slurry. The peristaltic pump is connected to the circulation pipe and is used to drive the slurry to circulate in a closed loop; The data monitoring system includes pressure gauges and thermometers installed at both ends of the transparent observation tube, and a flow meter installed on the circulation pipeline, for synchronously monitoring the pressure drop, temperature and flow rate of the slurry in the transparent observation tube; The real-time monitoring of pressure drop, temperature, and flow rate in the transparent observation tube is used to quantitatively characterize the thickness and spatial distribution of viscous deposits.

2. The experimental apparatus according to claim 1, characterized in that, The storage tank is equipped with a stirring component to fully mix the oil and wax particles with the oil before the experiment begins, so as to form a uniform, dense two-phase slurry.

3. The experimental apparatus according to claim 1 or 2, characterized in that, The circulation pipeline is also connected to a pressure purging pipeline, which is used to purge and dry the inside of the circulation pipeline with compressed gas after the experiment.

4. The experimental apparatus according to claim 1, characterized in that, The transparent observation tube is made of glass fiber, quartz or a transparent polymer composite material, and has oil resistance, temperature resistance and pressure resistance.

5. The experimental apparatus according to claim 1, characterized in that, The camera has a frame rate of no less than 1000 frames per second and is used to capture the transient motion trajectory, sedimentation process, and aggregation behavior of the oil and wax particles in the slurry.

6. The experimental apparatus according to claim 1, characterized in that, The flow meter is a mass flow meter, suitable for measuring the flow rate of non-conductive oil-based slurries.

7. The experimental apparatus according to claim 1, characterized in that, Both the first and second temperature-controlled water baths are equipped with independent temperature control systems to set and maintain the temperatures of the circulation pipeline and the storage tank, respectively.

8. The experimental apparatus according to claim 1, characterized in that, The detachable connector is a quick-release clamp type connector or a flange type connector, which facilitates the quick disassembly and replacement of the transparent observation tube.

9. The experimental apparatus according to claim 1, characterized in that, The data monitoring system also includes a data acquisition module and a host computer, which are used to collect, store and display the pressure drop, temperature, flow rate and high-speed camera image data in real time, and realize the time synchronization of multi-source data.

10. The experimental apparatus according to claim 1, characterized in that, The transparent observation tube is located on the horizontal straight section of the circulation pipeline, and the upstream inlet end of the transparent observation tube is farther than a preset distance from the outlet of the peristaltic pump and the nearest upstream pipeline bend.

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