Anti-thermal convection settling tank based on flow field regulation and settling method

Abstract

The present application relates to the technical field of oil recovery water treatment equipment, and particularly provides an anti-thermal convection settling tank based on flow field regulation and a settling method, which comprises a tank body and a pipeline system, the pipeline system is communicated with the tank body, and further comprises: a heat insulation inner cylinder arranged in the tank body and used for separating the internal space of the tank body into a main settling zone on the inner side of the heat insulation inner cylinder and an annular boundary layer zone on the outer side; and a slow flow component arranged between the heat insulation inner cylinder and the tank body and used for increasing the flow resistance of the fluid sinking along the tank wall; wherein the pipeline system is configured to directly introduce the mixture to be settled into the main settling zone. Through this design, a double mechanism of "thermal shielding-flow field decoupling" is constructed, so that the thermal convection interference can be effectively inhibited, the internal flow field can be maintained stable, and the separation efficiency can be guaranteed in a low-temperature and large-temperature-difference environment.

Description

Technical Field

[0001] This invention relates to the field of oil recovery water treatment technology and equipment, and in particular to a heat-resistant convection settling tank and settling method based on flow field regulation. Background Technology

[0002] In oil extraction and gathering processes, settling tanks are the core equipment for achieving three-phase gravity separation of oil, water, and slag. Their working principle primarily utilizes the density difference between the dispersed and continuous phases, causing the dispersed phase droplets to overcome fluid resistance and float or sink under gravity, thus completing phase separation. To ensure good fluidity of the crude oil and promote the coalescence of fine water droplets, the settling process is typically conducted under conditions maintaining a certain temperature (e.g., 40℃-70℃).

[0003] However, in northern my country or high-latitude cold regions, winter temperatures are extremely low, often reaching -20°C or even lower. For large settling tanks that rely primarily on gravity settling, this extreme temperature difference presents a severe challenge to the settling process.

[0004] In existing technologies, settling tanks are typically single-walled metal structures, directly exposed to the external atmosphere. Although the outer wall of the tank is usually covered with an insulation layer, a significant heat exchange still occurs between the fluid inside the tank and the external environment due to the large temperature difference between the inside and outside. This heat exchange results in the fluid temperature immediately adjacent to the inner wall being significantly lower than the fluid temperature in the central region of the tank. According to the principles of fluid mechanics and thermodynamics, a decrease in fluid temperature leads to an increase in its density. Therefore, under the influence of gravity, the cooled and heavier fluid near the tank wall forms a natural convection boundary layer that gradually accelerates downwards along the tank wall.

[0005] This temperature-driven wall-mounted flow can induce the following technical problems in practical engineering applications: First, the full-tank scale thermal convection circulation disrupts the laminar settling environment. The wall flow, with its large downward momentum, forces the fluid in the central region of the tank to undergo compensatory upward movement upon reaching the bottom. This large-scale circulation throughout the entire tank not only disturbs the originally calm horizontal flow field and introduces vertical interference velocities, but also interferes with the settling or floating process of fine droplets following Stokes' law, leading to a longer effective settling distance and reduced separation efficiency. Second, the cold fluid accelerating down the tank wall often has a high velocity when it reaches the bottom. This high-speed fluid directly impacts the bottom, easily causing a "scouring effect" and "entrainment effect" on the already settled sludge or water layer. This can cause the bottom sludge to be resuspended and entrained into the outlet with the water flow, or it can carry oil droplets that should float to the surface into the bottom water phase, increasing the risk of oil phase being mistakenly discharged through the bottom outlet and severely affecting the effluent quality. Finally, the lack of effective isolation in the cold wall surface directly leads to a decrease in the oil phase temperature at the liquid surface and edge areas. For crude oil with high wax content or high viscosity, the decrease in edge temperature will cause a sharp increase in the dynamic viscosity of the crude oil, and even wax precipitation and solidification may occur near the tank wall, further reducing the effective settling volume and potentially leading to poor oil drainage or the formation of "dead oil zones".

[0006] Therefore, how to provide a thermal convection-resistant settling tank that can effectively suppress thermal convection interference, maintain internal flow field stability, and ensure separation efficiency in low-temperature and large-temperature-difference environments has become an urgent problem to be solved. Summary of the Invention

[0007] The present invention aims to provide a heat-resistant convection settling tank and settling method based on flow field control, so as to effectively suppress heat convection interference, maintain internal flow field stability and ensure separation efficiency in low temperature and large temperature difference environments.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A heat-resistant convection settling tank based on flow field control includes a tank body and a piping system. The piping system connects to the tank body and further includes: an insulated inner cylinder disposed within the tank body to divide the internal space of the tank body into a main settling zone inside the insulated inner cylinder and an annular boundary layer zone outside the inner cylinder; and a flow-slowing component disposed between the insulated inner cylinder and the tank body to increase the flow resistance of the fluid settling along the tank wall. The piping system is configured to directly introduce the mixture to be settled into the main settling zone.

[0009] This design establishes a dual mechanism of "thermal shielding and flow field decoupling." At the thermodynamic level, the insulated inner cylinder uses physical heat to isolate the tank wall region, significantly affected by the low temperature of the external environment, from the main settling zone where the core separation process occurs. This reduces the radial temperature gradient within the main settling zone, thereby suppressing natural convection caused by temperature differences and maintaining a stable temperature field conducive to gravity separation. At the fluid dynamic level, the annular boundary layer region is defined as a "sacrificial zone" or "buffer zone," used to accommodate the denser descending fluid (wall flow) generated by the cooling of the tank wall. The introduction of the flow-slowing component increases frictional resistance, disrupting the continuity of fluid descending along the tank wall, effectively dissipating the kinetic energy of the descending fluid, and preventing high-velocity cold fluid from directly impacting the bottom of the tank and affecting the settled sludge or disrupting the bottom stratification structure.

[0010] Furthermore, the piping system includes: an inlet that penetrates the tank body and extends into the insulated inner cylinder to provide a passage for the mixture to be settled to enter the settling tank; an oil outlet and a water outlet, both of which are connected to the insulated inner cylinder and penetrate the tank body.

[0011] This design achieves spatial decoupling between the core separation process and the external thermal disturbance zone. The feeding, sedimentation separation, and post-phase separation discharge processes are confined as much as possible within the relatively constant thermal environment of the insulated inner cylinder. The liquid inlet extends directly into the insulated inner cylinder, preventing the high-temperature mixture to be separated from passing through the low-temperature annular zone on the outside during the initial entry phase. This reduces the increase in viscosity of the mixture or the stabilization of the emulsion system due to temperature drop, promoting droplet coalescence and sedimentation. Simultaneously, the oil and water outlets are directly discharged from the insulated inner cylinder, ensuring that the produced oil and water phases are effectively separated through sedimentation and are not contaminated by "backmixing" from the external cold fluid, thus helping to guarantee separation efficiency and the quality of the separated products.

[0012] Furthermore, the heat-insulating inner cylinder includes: a cylinder body having a through-cavity extending along the axial direction; an overflow collection assembly located at the upper end of the cylinder body for collecting the separated crude oil; and a flow stabilizing port penetrating the side wall of the cylinder body for providing a fluid communication channel between the through-cavity and the annular boundary layer region; wherein the oil outlet is connected to the overflow collection assembly, and the water outlet is connected to the through-cavity.

[0013] This design establishes a dynamic pressure balance based on the principle of communicating vessels, while simultaneously defining the path for fluid exchange. Technically, the overflow collection component utilizes the weir principle to collect only the relatively pure oil phase with low water content from the liquid surface, reducing water entrainment. The flow stabilizing port acts as a "pressure balancing valve." When the fluid within the annular boundary layer contracts in volume due to temperature decreases or experiences localized pressure changes due to sinking flow, the fluid in the main settling zone can compensate for the pressure through the flow stabilizing port, maintaining a relative balance of liquid levels inside and outside the insulated inner cylinder.

[0014] Furthermore, the overflow collection assembly includes: an overflow platform, which is arranged around the upper end of the cylinder; and a collection tank, which is configured in conjunction with the overflow platform to store crude oil overflowing from the overflow platform; wherein the oil outlet is connected to the collection tank.

[0015] This design clarifies the structure of the overflow collection assembly. The surrounding overflow platform ensures that the oil phase forms a relatively uniform laminar layer upon overflow. The collection tank acts as a buffer and temporary storage container, collecting intermittent or continuous overflows of crude oil before discharging them through the outlet.

[0016] Furthermore, the heat-insulating inner cylinder is connected to the tank body via a connecting assembly, which includes: a hollow disc connected to the inner wall of the tank; multiple suspension columns disposed on the hollow disc and connected to the top of the cylinder; and a radial guide assembly disposed along the circumference of the tank body to limit the radial displacement of the heat-insulating inner cylinder relative to the tank body and to allow relative thermal expansion displacement.

[0017] This design clarifies the connection method between the insulated inner cylinder and the tank body. Since the tank body is directly exposed to the external environment, while the insulated inner cylinder is immersed in a high-temperature medium, a significant temperature difference inevitably exists between them, leading to different thermal expansion rates. If a fully rigid connection were used, the enormous thermal stress could cause structural tearing or weld cracking. This design uses suspension columns to bear the weight, in conjunction with radial guide components, ensuring the coaxiality of the insulated inner cylinder and the outer tank body while allowing relative sliding between them at the radial guide components. This improves the mechanical integrity and safety of the unit under long-term thermal cycling conditions.

[0018] Furthermore, the radial guide assembly includes: multiple limiting guide blocks, which are evenly arranged along the circumference of the tank; multiple limiting guide rails, which are disposed on the inner wall of the tank and correspond one-to-one with the multiple limiting guide blocks; wherein, a fitting gap is provided between the limiting guide blocks and the corresponding limiting guide rails.

[0019] This design clarifies the structure of the radial guide assembly. It's important to note that the clearance between the guide block and the guide rail needs to be determined through routine testing based on the dimensions of the settling pipe. This clearance must allow for radial thermal expansion while limiting the sway of the inner insulation cylinder under liquid flow impact or external vibration. The limiting guide rail can be a U-shaped rail; this structure is simple and reliable, facilitates the hoisting of the inner insulation cylinder during production, and effectively resists lateral forces caused by uneven fluid flow. Combined with the limiting guide block, it keeps the inner insulation cylinder centered, improving the uniformity of the annular boundary layer width and thus enhancing the flow field symmetry.

[0020] Furthermore, the flow-retarding component includes: a plurality of first guide vanes, which are uniformly arranged circumferentially along the outer wall of the heat-insulating inner cylinder and axially along the inner cylinder; a plurality of second guide vanes, which are uniformly arranged circumferentially along the inner wall of the tank and axially along the tank; wherein the first guide vanes and the second guide vanes are axially staggered along the annular boundary layer region.

[0021] This design creates a tortuous flow channel within the annular boundary layer region. Multiple staggered first and second guide vanes force the fluid descending along the tank wall to continuously change its flow direction, increasing the path length of the fluid flow. This dissipates the kinetic energy of the descending fluid. It significantly reduces the vertical velocity component of the fluid reaching the bottom of the tank, allowing it to enter the bottom region at a gentler, lower speed, thus avoiding impact and entrainment on the bottom sediment layer.

[0022] Furthermore, the settling tank also includes a flow guiding structure located at the bottom of the insulated inner cylinder, the flow guiding structure having a guide surface extending radially outward along the insulated inner cylinder.

[0023] This design enhances the directional flow field at the bottom and improves hydraulic transport. When the fluid, slowed by the flow-decelerating components, reaches the bottom of the insulated inner cylinder, the guide surface smoothly transforms its vertical downward flow into a horizontal or oblique flow radially outward along the tank bottom. This change in flow direction further prevents the resuspension of sediments that might occur if the fluid directly reaches the center of the tank bottom. Furthermore, the residual kinetic energy of the fluid creates a "hydraulic cleaning layer" close to the tank bottom, which helps to move the sludge settled at the bottom towards the sludge discharge port, thus assisting in sludge discharge and reducing accumulation in dead corners at the tank edges.

[0024] The present invention also provides a sedimentation method for separating mixtures using the sedimentation tank as described above. The method includes: directly introducing the mixture to be sedimented into the main sedimentation zone inside the insulated inner cylinder through a pipeline system, and performing gravity separation under the thermal shielding of the insulated inner cylinder; allowing part of the fluid in the main sedimentation zone to enter the annular boundary layer zone between the insulated inner cylinder and the tank body; using a slow-flow component in the annular boundary layer zone to decelerate the descending fluid generated by the cooling of the tank wall, thereby reducing the kinetic energy of the descending fluid; the decelerated descending fluid reaching the bottom of the tank body and forming a hydraulic transport layer, carrying the sludge settled from the main sedimentation zone and discharging it through the sludge discharge port at the bottom of the tank body.

[0025] Furthermore, the fluid within the main settling zone is allowed to enter the annular boundary layer region between the insulated inner cylinder and the tank body: some fluid enters the annular boundary layer from the channel below the designed oil-water interface of the insulated inner cylinder.

[0026] By placing the connecting channel (i.e., the aforementioned flow stabilization port, etc.) below the designed oil-water interface, it is possible to ensure that only the water phase can enter the outer annular boundary layer region, thus guaranteeing the crude oil recovery rate to a certain extent.

[0027] The present invention has at least one of the following beneficial effects: 1. This invention constructs a "thermal shielding" mechanism in physical space by setting up an insulated inner cylinder, isolating the tank wall region (annular boundary layer region) significantly affected by the low temperature of the external environment from the main settling zone where the core separation process occurs. Macroscopically, it blocks the path of direct heat conduction from the tank wall cold source to the settling center, reducing the radial temperature gradient within the main settling zone, thereby suppressing the natural convection circulation driven by temperature difference within the main settling zone and helping to maintain a laminar flow environment. Simultaneously, a flow-slowing component is installed within the annular boundary layer region. For the inevitable downward flow on the tank wall due to tank wall cooling, the flow-slowing component effectively dissipates the kinetic energy of the downward fluid by increasing the frictional resistance, disrupting its continuous accelerated descent. This not only prevents the impact and entrainment of high-velocity cold fluid on the bottom sediment layer but also avoids backmixing caused by compensating upflow, thus significantly improving the flow field stability under temperature difference conditions.

[0028] 2. By configuring a pipeline system to directly introduce the mixture to be settled into the main settling zone of the insulated inner cylinder, and connecting the oil outlet and water outlet to the insulated inner cylinder, this invention achieves spatial decoupling between the separation process and the external thermal disturbance zone. The mixture to be separated avoids flowing through the low-temperature annular boundary layer region in the initial stage, thus maintaining a higher fluid temperature and lower dynamic viscosity, which is conducive to the coalescence and settling of fine droplets. Furthermore, the produced oil and water phases are directly discharged from the thermally stable insulated inner cylinder, effectively preventing the separated components from being recontaminated or emulsified by any unseparated cold fluid that may be present on the outside. This helps maintain good fluidity and separation quality when processing high-wax or high-viscosity crude oil.

[0029] 3. Utilizing the descending fluid slowed down by the flow-regulating components within the annular boundary layer region. Through the bottom guiding structure, the residual kinetic energy of this fluid is converted from the vertical direction into a horizontal or oblique flow radially outward along the tank bottom, forming a "hydraulic transport layer" close to the tank bottom. This transforms the "cold wall surface descending flow," typically considered a disruptive factor in existing technologies, into a beneficial "hydraulic cleaning force," applying thrust to the sludge settled at the tank bottom and assisting its migration towards the discharge port. This, to some extent, solves the problem of sludge accumulation dead zones easily forming at the bottom edge of the settling tank, extending the equipment's cleaning cycle.

[0030] 4. Considering the significant temperature difference between the insulated inner cylinder and the tank body and the resulting differential thermal expansion, this invention employs a radially flexible guiding connection strategy. The radial guiding assembly restricts the radial displacement of the insulated inner cylinder to ensure coaxiality, while allowing the insulated inner cylinder to undergo axial free thermal expansion or contraction relative to the tank body. This effectively releases structural thermal stress caused by the temperature difference, avoids the risk of weld tearing or structural deformation that may result from rigid connections, and improves the mechanical integrity and safety of the device during long-term operation. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of the heat-resistant convection settling tank based on flow field control according to the present invention; Figure 2 This is a side view of the heat-resistant convection settling tank based on flow field control according to the present invention. Figure 3 This is a cross-sectional view of the heat-resistant convection settling tank based on flow field control according to the present invention. Figure 4 This is a cross-sectional view of the tank body of the present invention; Figure 5 This is a schematic diagram of the structure of the heat-insulating inner cylinder and connecting components of the present invention; Figure 6 This is a schematic diagram of the structure of the heat-insulating inner cylinder of the present invention; Figure 7 This is a side view of the heat-insulating inner cylinder of the present invention; Figure 8 This is a three-dimensional sectional view of the heat-insulating inner cylinder of the present invention; Figure 9 This is a schematic diagram of the overflow collection component of the present invention; Figure 10 This is a side view of the overflow collection assembly of the present invention; Figure 11 This is a schematic diagram of the flow guiding structure of the present invention; Figure 12 This is a schematic diagram of the radial guide assembly of the present invention.

[0032] The components include: 1. Tank body; 11. Liquid inlet; 12. Oil outlet; 13. Water outlet; 14. Sewage outlet; 15. Manhole; 2. Insulated inner cylinder; 21. Cylinder body; 22. Overflow collection assembly; 221. Overflow platform; 222. Collection tank; 23. Flow stabilizing port; 3. Flow slowing assembly; 31. First guide vane; 32. Second guide vane; 41. Hollow disc; 42. Suspension column; 43. Radial guide assembly; 431. Limiting guide block; 432. Limiting guide rail; 5. Flow guiding structure. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "front end", "rear end", "inner side", "outer side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0035] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] Example 1 This embodiment provides a heat-resistant convection settling tank based on flow field control, such as... Figures 1 to 12As shown, the system includes a tank 1 and a piping system connected to it. An insulated inner cylinder 2 is installed inside the tank 1, physically dividing the fluid space inside the tank 1 into a main settling zone located inside the inner cylinder 2 and an annular boundary layer zone located outside the inner cylinder 2. Simultaneously, a flow-retarding component 3 is installed between the inner cylinder 2 and the tank 1. The piping system is configured to directly introduce the mixture to be settled into the main settling zone. This structural layout establishes a dual mechanism of "thermal shielding-flow field decoupling." At the thermodynamic level, the inner cylinder 2 utilizes physical thermal insulation to separate the tank wall region, which is significantly affected by the low temperature of the external environment, from the main settling zone where the core separation process occurs. This significantly reduces the radial temperature gradient within the main settling zone, thereby suppressing natural convection caused by temperature differences within the main settling zone and helping to maintain a stable temperature field favorable for gravity separation within the main settling zone. At the fluid dynamics level, the annular boundary layer region is defined as a "sacrificial zone" or "buffer zone" specifically designed to accommodate the denser descending fluid (i.e., wall flow) generated by the cooling effect of the tank wall. The slow-flow component 3 is designed to increase the flow resistance of the fluid descending along the tank wall, disrupt the continuity of the fluid's accelerated descent along the tank wall, thereby effectively dissipating the kinetic energy of the descending fluid and preventing the high-velocity cold fluid from directly impacting the bottom of the tank, thus avoiding disturbance to the settled sludge layer or damage to the bottom stratification structure.

[0037] Furthermore, the piping system includes a liquid inlet 11, an oil outlet 12, and a water outlet 13. The liquid inlet 11 penetrates the wall of the tank 1 and extends further inward into the insulated inner cylinder 2, providing an independent channel for the mixture to be settled to enter the main settling zone of the settling tank. The oil outlet 12 and water outlet 13 are also connected to the insulated inner cylinder 2 and extend through the tank 1 to the outside. This arrangement achieves spatial decoupling of the core separation process from the external thermal disturbance zone, effectively confining the feeding, settling separation, and post-phase separation discharge processes within the relatively constant thermal environment of the insulated inner cylinder 2. The liquid inlet 11 extends directly into the insulated inner cylinder 2, preventing the high-temperature mixture to be separated from flowing through the low-temperature annular zone on the outside during the initial entry stage. This reduces the increase in viscosity of the mixture or the stabilization of the emulsion system caused by temperature drop, facilitating droplet coalescence and settling according to Stokes' law. Meanwhile, the oil outlet 12 and water outlet 13 are directly sampled and discharged from the heat-insulated inner cylinder 2, so that the produced oil phase and water phase are both fluids that have been effectively separated by sedimentation and have not been contaminated by the "back-mixing" of the external cold fluid, which helps to ensure the separation efficiency and the quality of the final separation product.

[0038] Specifically, in specific implementations, the tank also includes a drain outlet 14, a manhole 15, etc. Other conventional structures are also provided on the tank body. Those skilled in the art should know that these conventional features are obviously within the protection scope of this application.

[0039] In some embodiments, the specific structure of the insulated inner cylinder 2 includes a cylinder 21 extending axially through the inner cavity, an overflow collection assembly 22 located at the upper end of the cylinder 21, and a flow stabilizing port 23 penetrating the side wall of the cylinder 21. The oil outlet 12 communicates with the overflow collection assembly 22, and the water outlet 13 communicates with the inner cavity. The flow stabilizing port 23 provides a fluid communication channel between the inner cavity and the annular boundary layer region. This structure establishes a dynamic pressure balance system based on the principle of communicating vessels, while defining a specific path for fluid exchange. Technically, the overflow collection assembly 22 utilizes the weir principle, tending to collect only the relatively pure oil phase with low water content from the liquid surface, reducing water entrainment. The flow stabilizing port 23 acts as a "pressure balancing valve." When the fluid in the annular boundary layer region shrinks in volume due to temperature reduction or changes in local pressure due to sinking flow, the fluid in the main settling zone can undergo appropriate pressure compensation through the flow stabilizing port 23, thereby maintaining the relative balance of liquid levels inside and outside the heat-insulating inner cylinder 2 and preventing the heat-insulating inner cylinder 2 from deforming due to excessive pressure difference.

[0040] Furthermore, the overflow collection assembly 22 specifically includes an overflow platform 221 circumferentially disposed on the upper end of the cylinder 21 and a collection trough 222 configured in conjunction with the overflow platform 221. The oil outlet 12 is connected to the collection trough 222. The circumferential overflow platform 221 allows the oil phase to form a relatively uniform laminar thin layer along the circumference when overflowing, avoiding interface disturbances caused by point-like suction. The collection trough 222 serves as a buffer and temporary storage container, collecting intermittent or continuous overflowing crude oil before discharging it through the oil outlet 12, which is beneficial to the stability of the output flow rate.

[0041] In terms of the connection structure, the insulated inner cylinder 2 is connected to the tank body 1 via a connecting assembly. This connecting assembly includes a hollow disk 41 connected to the inner wall of the tank body 1, multiple suspension columns 42 disposed on the hollow disk 41 and connected to the top of the cylinder 21, and a radial guide assembly 43 arranged circumferentially along the tank body 1. The radial guide assembly 43 is used to limit the radial displacement of the insulated inner cylinder 2 relative to the tank body 1 and is configured to allow relative thermal expansion displacement between the two. Since the tank body 1 is directly exposed to the external environment, while the insulated inner cylinder 2 is immersed in a high-temperature medium, there is usually a significant temperature difference between the two under operating conditions, leading to a difference in axial thermal expansion. If a fully rigid connection is used, the enormous thermal stress may lead to structural tearing or weld cracking risks. In this embodiment, the weight of the heat-insulating inner cylinder 2 is borne by the suspension column 42. With the help of the radial guide component 43, while ensuring the coaxiality of the heat-insulating inner cylinder 2 and the outer tank 1, the heat-insulating inner cylinder 2 and the tank 1 are allowed to slide relative to each other axially at the radial guide component 43, thereby significantly improving the mechanical integrity and safety of the device under long-term thermal cycling conditions.

[0042] In a preferred embodiment, the radial guide assembly 43 includes a plurality of limiting guide blocks 431 uniformly arranged along the circumference of the tank body 1, and a plurality of limiting guide rails 432 disposed on the inner wall of the tank body 1 and corresponding one-to-one with the limiting guide blocks 431. A fitting gap is provided between the limiting guide blocks 431 and the corresponding limiting guide rails 432. The size of this fitting gap is usually determined by conventional calculation or experiment based on the size of the settling tank and the thermal expansion coefficient of the material, aiming to both allow for radial thermal expansion and limit the swaying amplitude of the insulated inner cylinder 2 under liquid flow impact or external vibration. The limiting guide rails 432 can be U-shaped guide rails or other profiles with limiting functions. This structure is simple and reliable, facilitates the hoisting and positioning of the insulated inner cylinder 2 during production, and can effectively resist lateral forces caused by uneven fluid flow. Together with the limiting guide blocks 431, it keeps the insulated inner cylinder 2 centered, helping to improve the width uniformity of the annular boundary layer region, thereby improving the symmetry of the overall flow field.

[0043] The specific structure of the flow-slowing component 3 includes multiple first guide vanes 31 uniformly arranged circumferentially and axially along the outer wall of the insulated inner cylinder 2, and multiple second guide vanes 32 uniformly arranged circumferentially and axially along the inner wall of the tank 1. The first guide vanes 31 and the second guide vanes 32 are axially staggered along the annular boundary layer region. This staggered distribution design creates a tortuous flow channel within the annular boundary layer region. When the descending fluid passes through the first guide vanes 31 and the second guide vanes 32, the path length of the fluid flow is significantly increased. This process can effectively consume the kinetic energy of the descending fluid through wall friction, thereby significantly reducing the vertical velocity component of the fluid when it reaches the bottom of the tank, allowing it to enter the bottom region at a relatively gentle and low speed, thus avoiding the impact and entrainment of high-speed fluid on the bottom sediment layer.

[0044] In addition, the settling tank also includes a flow guiding structure 5 located at the bottom of the insulated inner cylinder 2. The flow guiding structure 5 has a guide surface (which can be a skirt-shaped or conical structure) extending radially outward along the insulated inner cylinder 2. When the fluid, after being slowed down by the flow slowing component 3, reaches the bottom of the insulated inner cylinder 2, the guide surface smoothly transforms it from a vertically downward flow to a horizontal or oblique flow radially outward along the bottom of the tank, thereby enhancing the directional sorting of the bottom flow field and the hydraulic transport function. This change in flow direction, on the one hand, further avoids the resuspension of sediments that may be caused by the fluid directly impacting the center of the tank bottom; on the other hand, it utilizes the residual kinetic energy of the fluid to form a "hydraulic cleaning layer" that diffuses outward close to the bottom of the tank, which helps to push the sludge settled at the bottom of the tank toward the sludge discharge port, playing an auxiliary role in sludge discharge and reducing sludge accumulation in the dead corners of the tank body 1.

[0045] Example 2 This embodiment provides a sedimentation method for separating mixtures using the sedimentation tank of Embodiment 1. The sedimentation method mainly includes: The mixture to be settled is directly introduced into the main settling zone inside the insulated inner cylinder 2 through the pipeline system. Gravity separation is carried out under the thermal shielding environment provided by the insulated inner cylinder 2, so that the oil, water and slag phases are separated under the interference of a small temperature gradient.

[0046] A portion of the fluid within the main settling zone is allowed to enter the annular boundary layer region between the insulated inner cylinder 2 and the tank body 1. Specifically, a portion of the fluid enters the annular boundary layer through a channel (i.e., the aforementioned flow stabilizing port 23) located below the designed oil-water interface in the insulated inner cylinder 2. By placing the connecting channel below the designed oil-water interface, and utilizing the principle of oil-water density difference, it is possible for virtually only the water phase (or a low-oil-content water phase) to enter the outer annular boundary layer region, thereby forming a liquid seal and preventing the upper crude oil from entering the low-temperature region, thus ensuring the crude oil recovery rate to a certain extent.

[0047] The flow-slowing component 3 in the annular boundary layer region is used to slow down the descending fluid generated by the cooling of the tank wall 1, thereby reducing the kinetic energy of the descending fluid.

[0048] After being slowed down, the descending fluid reaches the bottom of the tank 1 and forms a hydraulic transport layer under the guidance of the flow guiding structure 5. The sludge that has settled from the main settling area and slid down to the bottom is discharged through the sludge discharge port at the bottom of the tank 1.

[0049] Working principle: The working principle of the heat-resistant convection settling tank described in this invention is as follows: 1. During separation, the mixture to be separated (such as water-containing crude oil) is directly introduced into the main settling zone inside the insulated inner cylinder 2 through the inlet 11 of the pipeline system. Due to the physical presence of the insulated inner cylinder 2, its cylinder wall acts as a thermal resistance layer, effectively blocking or delaying the heat conduction from the external low-temperature environment to the center of the main settling zone through the tank wall. Therefore, a relatively high fluid temperature can be maintained in the main settling zone. According to the principles of fluid mechanics, a higher temperature helps to reduce the dynamic viscosity of the mixture, thereby reducing the frictional resistance of the dispersed phase droplets settling or floating in the continuous phase. In this stable high-temperature, low-disturbance environment, the mixture undergoes gravity stratification: the less dense oil phase gathers at the top, the denser water phase settles downwards, and the heavier solid impurities (sludge) settle to the bottom.

[0050] 2. During the separation process, the main settling zone and the outer annular boundary layer zone are kept in fluid communication through the stabilizing port 23. Since the stabilizing port 23 is positioned below the designed oil-water interface and in the aqueous phase region, according to the principle of communicating vessels and hydrostatic equilibrium, the hot oil phase separated from the upper layer is restricted from entering the low-temperature annular boundary layer region on the outside, preventing the crude oil from solidifying or adhering to the wall due to cooling. Simultaneously, when fluctuations in operating conditions (such as changes in feed flow rate or volume expansion / contraction caused by temperature) result in a small pressure difference between the inner and outer regions, the aqueous phase fluid can flow bidirectionally through the stabilizing port 23 to compensate for the flow, thereby dynamically maintaining the liquid level and pressure balance inside and outside the insulated inner cylinder 2.

[0051] 3. The annular boundary layer region located outside the insulated inner cylinder 2 directly contacts the tank wall, which is affected by the external environment. When the tank wall temperature is lower than the fluid temperature, the fluid layer adjacent to the tank wall increases in density due to cooling, forming natural convection (wall flow) that accelerates downwards along the wall. The flow-slowing components 3 distributed within the annular boundary layer region begin to function. The staggered first guide vane 31 and second guide vane 32 force the descending fluid to continuously change its direction, transforming the vertically downward straight flow into a tortuous labyrinthine flow. This process significantly increases the frictional resistance and local shape resistance of the fluid, dissipating the gravitational potential energy accumulated in the descending flow. Therefore, the fluid velocity reaching the bottom is significantly reduced, avoiding impact on the flow field at the bottom of the tank.

[0052] 4. After being slowed down by the flow-retarding component 3, the fluid finally reaches the bottom area of ​​tank 1. At this point, the flow-guiding structure 5 located at the bottom of the insulated inner cylinder 2 uses its outward-extending guide surface to smoothly guide the originally vertically downward residual flow field into a horizontal or oblique flow field radially outward along the bottom of the tank. A layer of outward-diffusing "hydraulic transport layer" is formed at the bottom of the tank. The transport layer applies tangential thrust to the sludge settled at the bottom of the tank, helping the sludge overcome the bottom friction and move towards the sludge discharge port at the bottom of tank 1 for discharge. The thermal convection effect, which was originally harmful to the separation process, is transformed into an auxiliary force that is beneficial to bottom sludge removal, completing the closed-loop working process of self-cleaning and separation of the settling tank.

[0053] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A heat-resistant convection settling tank based on flow field control, comprising a tank body (1) and a piping system, wherein the piping system is connected to the tank body (1), characterized in that, Also includes: The heat-insulating inner cylinder (2) is located inside the tank body (1) and is used to divide the internal space of the tank body (1) into the main settling zone inside the heat-insulating inner cylinder (2) and the annular boundary layer zone outside the tank body (1). The flow-retarding component (3) is disposed between the heat-insulating inner cylinder (2) and the tank body (1) to increase the flow resistance of the fluid as it sinks along the tank wall; The pipeline system is configured to directly introduce the mixture to be settled into the main settling zone.

2. The settling tank according to claim 1, characterized in that, The piping system includes: The inlet (11) penetrates the tank body (1) and extends into the heat-insulating inner cylinder (2) to provide a channel for the mixture to be settled to enter the settling tank; Oil outlet (12) and water outlet (13) are connected to the heat-insulating inner cylinder (2) and pass through the tank body (1).

3. The settling tank according to claim 2, characterized in that, The heat-insulating inner cylinder (2) includes: The cylindrical body (21) has a through-cavity extending along the axial direction; An overflow collection assembly (22) is located at the upper end of the cylinder (21) and is used to collect the separated crude oil. A flow stabilizing port (23) penetrates the side wall of the cylinder (21) and is used to provide a fluid communication channel between the penetrating inner cavity and the annular boundary layer region; The oil outlet (12) is connected to the overflow collection assembly (22), and the water outlet (13) is connected to the through cavity.

4. The settling tank according to claim 3, characterized in that, The overflow collection component (22) includes: An overflow platform (221) is arranged around the upper end of the cylinder (21); A collection tank (222) is provided in conjunction with the overflow platform (221) for storing crude oil overflowing from the overflow platform (221); The oil outlet (12) is connected to the collection tank (222).

5. The settling tank according to claim 3, characterized in that, The heat-insulating inner cylinder (2) is connected to the tank body (1) via a connecting assembly, the connecting assembly comprising: Hollow disc (41) is connected to the inner wall of the tank (1); Multiple suspension columns (42) are provided on the hollow disk (41) and connected to the top of the cylinder (21); A radial guide assembly (43), arranged circumferentially along the tank body (1), is used to limit the radial displacement of the heat-insulating inner cylinder (2) relative to the tank body (1) and allow axial relative thermal expansion displacement.

6. The settling tank according to claim 5, characterized in that, The radial guide assembly (43) includes: Multiple limiting guide blocks (431) are evenly arranged along the circumference of the tank body (1); Multiple limiting guide rails (432) are provided on the inner wall of the tank (1) and correspond one-to-one with multiple limiting guide blocks (431); The limiting guide block (431) and the corresponding limiting guide rail (432) are provided with a fitting gap.

7. The settling tank according to claim 1, characterized in that, The slow-flow component (3) includes: Multiple first guide vanes (31) are uniformly arranged circumferentially along the outer wall of the heat-insulating inner cylinder (2) and uniformly arranged axially along the inner cylinder (2); Multiple second guide vanes (32) are uniformly arranged circumferentially along the inner wall of the tank (1) and uniformly arranged axially along the tank (1); The first guide vane (31) and the second guide vane (32) are axially misaligned along the annular boundary layer region.

8. The settling tank according to claim 1, characterized in that, Also includes: A flow guiding structure (5) is provided at the bottom of the heat-insulating inner cylinder (2), and the flow guiding structure has a guide surface that extends radially outward along the heat-insulating inner cylinder (2).

9. A sedimentation method for separating mixtures using the sedimentation tank according to any one of claims 1-8, characterized in that, Settlement methods include: The mixture to be settled is directly introduced into the main settling zone inside the insulated inner cylinder (2) through the pipeline system, and gravity separation is carried out under the thermal shielding of the insulated inner cylinder (2); Allow some fluid in the main settling zone to enter the annular boundary layer zone between the insulated inner cylinder (2) and the tank body (1); The slow-flow component (3) in the annular boundary layer region is used to decelerate the sinking fluid generated by the cooling of the tank wall (1) and reduce the kinetic energy of the sinking fluid. The decelerated sinking fluid reaches the bottom of the tank and forms a hydraulic transport layer, carrying the sludge that has settled from the main settling zone and is discharged through the sludge discharge port at the bottom of the tank (1).

10. The method according to claim 9, characterized in that, The provision allows a portion of the fluid within the main settling zone to enter the annular boundary layer region between the insulated inner cylinder (2) and the tank body (1), wherein: The fluid enters the annular boundary layer from the channel below the oil-water interface of the heat-insulating inner cylinder (2).

Images