Sand-containing oil liquid multi-stage treatment system combining green electric energy and industrial waste heat

Abstract

The application discloses a sand-containing oil liquid multistage treatment system combining green electric energy and industrial waste heat, and relates to the field of sand-containing crude oil treatment on offshore oil fields. The system comprises a double-heat-source intelligent heating system, an interlaced-hole pretreatment sand discharge system and a cyclone fine separation system. The double-heat-source system comprises parallel green electric heating and waste heat recovery heat exchange devices, and the heating path is dynamically switched through an intelligent module. The pretreatment system realizes sand grain pre-separation, and the cyclone fine separation system is composed of a plurality of cyclone sand removal core pipes provided with spiral annular super oil channels. Through four-stage collaborative design, the application solves the problems of limited space on offshore platforms, high energy consumption for separation of high-viscosity crude oil, easy plugging, difficulty in capturing fine particles and high sand grain residual oil rate, is suitable for deep sea high-pressure environment, realizes efficient separation of sand-containing crude oil, low residual oil recovery and low-carbon energy saving, and has a separation efficiency of greater than or equal to 98% and a residual oil rate of less than 2%.

Description

Technical Field

[0001] This invention relates to the technical field of offshore oilfield sand-containing crude oil processing equipment, specifically to a multi-stage processing system for sand-containing oil that combines green electricity and industrial waste heat. It is particularly suitable for offshore platforms with limited space, and can achieve efficient separation of sand-containing crude oil, recovery of sand particles with low residual oil rate, and utilization of waste heat, thus solving the limitations of traditional equipment in terms of high-viscosity crude oil separation, fine particle capture, energy consumption control, and space adaptability. Background Technology

[0002] With accelerated industrialization, global crude oil consumption continues to grow, exceeding 100 million barrels per day in 2023. Onshore oil fields face reserve depletion due to long-term exploitation, making offshore oil fields a crucial option for supplementing energy shortages. Offshore crude oil reserves account for approximately 30% of global reserves, mainly distributed in the Persian Gulf, North Sea, Gulf of Mexico, and coastal areas of West Africa. Deep-sea oil fields with depths exceeding 1000 meters and ultra-deep-sea oil fields with depths exceeding 3000 meters possess enormous development potential. The development of deep-sea drilling platforms such as semi-submersible platforms and tension leg platforms, subsea production systems such as subsea production trees and subsea pipelines, and dynamic positioning technologies have made extraction possible in the high-pressure and highly corrosive environments of the deep sea. Coastal countries are accelerating the development of their offshore oil and gas resources to reduce reliance on concentrated onshore oilfield production areas and ensure energy supply security. Crude oil extraction is accompanied by large amounts of formation water, with a water cut of 70%–90%, forming stable emulsions that require separation using demulsifiers, electrochemical, or centrifugal techniques. Demulsification efficiency is even lower in the low-temperature environment of the deep sea. Solid particles such as formation sand and rust can easily abrade equipment like pumps and pipelines, requiring multi-stage treatment via hydrocyclones and filters. However, limited space on offshore platforms restricts equipment size. The limited area of ​​offshore platforms necessitates miniaturization and integration of separation equipment, creating a trade-off between separation efficiency and equipment size. Salts and acidic gases in seawater and crude oil can corrode equipment, while wax and inorganic salt deposits form scale, affecting separation efficiency and equipment lifespan. Platform movement and wave impacts cause instability in the separation process, requiring real-time adjustments to parameters such as flow rate and pressure via an automated control system. Heavy crude oil has high viscosity and poor fluidity, requiring heating or the addition of diluents during separation, resulting in high energy consumption and complex processes. High wax content can cause solidification in pipelines and equipment, increasing separation difficulty.

[0003] The cyclone separator used in existing technologies, such as patent CN119236476A, a geothermal water sand removal device for geothermal utilization, operates as follows: geothermal water enters the main body of the cyclone separator tangentially through the inlet pipe. The water flows down in a rotating motion along the inner wall, and denser sand and gravel settle to the bottom waste inlet under centrifugal force. After reaching the cone area, the water flow becomes an upward flow and is processed by the top filtration and screening structure: the upward water flow passes through screen plate one with larger filter holes and screen plate two with smaller filter holes, and the sand and gravel are graded and intercepted. By driving a gear set with a motor, the reserved groove two on the side wall of the outlet pipe can be rotated to align with the reserved groove one (below screen plate one) or reserved groove three (below screen plate two) on the fixed sleeve, thereby selecting different precision water outlet paths—coarse filtration (reserved groove one) is selected for industrial water, and fine filtration (reserved groove three) is selected for domestic water. As the rising water flows through the check valve, the spiral guide grooves on the upper surface of the conical block guide residual sand and gravel into the conical holes. The inverted conical design of the holes prevents backflow of sand and gravel. Simultaneously, the water flow drives the agitator blades to rotate, causing suspended light sand and gravel to gather and settle towards the center. During operation, as the motor drives the screen plate to rotate, the cleaning structure at the bottom works synchronously: the gear three on the edge of the screen plate meshes with the internal gear on the inner wall, driving the cleaning brush to revolve and rotate, brushing away accumulated sand on the inner wall. The sand and gravel fall through the gaps in the retainer to the waste outlet. When stopping the machine, the reserved tank can be closed to block the water flow, allowing the sand and gravel to settle further. Finally, the purified geothermal water is discharged from the outlet pipe, and the sand and gravel are disposed of uniformly through the bottom waste outlet.

[0004] Currently, traditional cyclone separation structures can achieve particle separation and have the characteristics of compact structure and no need for additional power, but they have the following problems: (1) The equipment integrates multiple mechanical structures such as rotating screen plate, gear transmission, and self-cleaning. Precision parts are in a sandy water environment for a long time, which may increase the risk of wear and maintenance frequency, and require high professionalism in daily operation and maintenance. (2) The motor needs to drive the screen plate rotation, cleaning structure and path switching function at the same time, and the stirring blades rely on water flow power, which may affect the stirring effect under low flow conditions. The coordinated operation of multiple systems may bring additional energy consumption, and the actual energy efficiency needs to be further verified. The boundary conditions for sand and gravel separation are highly dependent. (3) The design of the guide channel and the conical hole to prevent backflow needs to be strictly matched with the direction and velocity of the inlet cyclone. If the water flow parameters fluctuate (such as unstable flow or sudden change in sand content), it may weaken the sand and gravel guiding effect, leading to the risk of light particles escaping. (4) The rotary seal between the outlet pipe and the fixed sleeve needs to withstand repeated sand and gravel friction and water pressure changes. The sealing performance may decay under long-term use, and there is a risk of leakage or impurities seeping into the internal channel. (5) The sieve plate aperture is fixed, and the filtration accuracy can only be switched by path selection. The filter hole size cannot be dynamically adjusted. If a wider range of sand and gravel particle sizes is required, the machine may need to be stopped and the sieve plate replaced. (6) The actual verification of the cleaning effect is insufficient. The self-cleaning mechanism of the brush depends on the rotation of the sieve plate, but the sieve plate area is easily blocked by large sand and gravel particles, which may limit the coverage of the brush's revolution or rotation. The cleaning effect of the inner wall corners needs to be verified under actual working conditions. Summary of the Invention

[0005] To address the aforementioned issues, this invention aims to propose a multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat. Through a four-stage synergistic system of "dual heat source heating - pretreatment sand removal - cyclone fine separation - super-oleophilic oil removal", it achieves efficient treatment of sand-containing crude oil.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A multi-stage treatment system for sand-containing oil combining green electricity and industrial waste heat includes a dual-heat-source intelligent heating system, a staggered-hole pretreatment sand removal system, and a cyclone fine separation system. The dual-heat-source intelligent heating system includes a parallel green electricity heating heat exchange device and a waste heat recovery heat exchange device, and the heating path is dynamically adjusted through an intelligent switching control module. The staggered-hole pretreatment sand removal system is located between the heat exchange device and the cyclone separation system to achieve pre-separation of sand particles. The cyclone fine separation system consists of multiple cyclone sand removal core tubes, and a spiral annular super-oleophilic modified sand collection channel is set inside the cyclone sand removal core tube.

[0008] Furthermore, the green electric heating heat exchange device includes an external electric heat tracing device for the heat exchange tubes, a first internal spiral channel device for the heat exchange tubes, a multi-tube bundle integrated device for the heat exchange tubes, and a first temperature detection and transmission device. The external electric heat tracing device for the heat exchange tubes uses a self-regulating electric heat tracing tape made of high-molecular conductive plastic with a rectangular cross-section. It is tightly wound around the outside of the pipe of the first internal spiral channel device for the heat exchange tubes, with a winding spacing of 10-20mm. The power source is from offshore wind power generation devices and solar photovoltaic power generation devices. The first internal spiral channel device for the heat exchange tubes includes 2-8 spiral blade units, each with a thickness of 3-5mm and an inclination angle of 15°. °-30°, with a pitch 2-5 times the pipe diameter; the heat exchanger tube multi-tube bundle integrated device is made of corrosion-resistant alloy steel and has multiple sets of positioning brackets inside. The positioning brackets have positioning holes adapted to the outer diameter of the heat exchanger tubes for fixing 4-20 heat exchanger tubes. The two ends of the heat exchanger tube multi-tube bundle integrated device are connected to the upstream and downstream pipelines through the first flange, and the flange sealing surface uses a metal spiral wound gasket; the first temperature detection and transmission device uses a platinum resistance temperature sensor with a measurement accuracy of ±0.1℃, installed at the outlet of the heat exchanger tube, and has a built-in signal processing circuit to convert the resistance signal into a 4-20mA or 0-5V standard signal.

[0009] Furthermore, the waste heat recovery heat exchange device includes a shell-and-tube heat exchanger, a second heat exchange tube internal spiral channel device, and a second temperature detection and transmission device; the shell-and-tube heat exchanger is a cylindrical shell with multiple heat exchange tubes arranged inside to form the tube side, and baffles are installed in the shell side. The baffles have a segmental structure with a segmental ratio of 20%-40%. The tube side and shell side are arranged in a counter-current manner. The heating fluid is industrial waste heat fluid or seawater heated by associated gas combustion. When associated gas combustion is used to heat seawater, a special filtration device and seawater circulation system are provided. Before the waste heat fluid is introduced, it undergoes impurity filtration and flow regulation treatment. The two ends of the shell-and-tube heat exchanger are connected to other pipelines through second flanges, and the heat exchange tubes are fixed to the tube sheet by expansion or welding.

[0010] Furthermore, the intelligent switching control module is based on PLC control and includes a wind and solar power monitoring unit and a waste heat source monitoring unit. The wind and solar power monitoring unit uses a Hall effect sensor and an ultrasonic anemometer to monitor the output power of wind and solar power in real time with an accuracy of ±1%. A switching signal is triggered when the power is less than 30% of the rated value. The waste heat source monitoring unit uses a K-type shell-side thermocouple and an electromagnetic flowmeter. The thermocouple accuracy is ±0.5℃, and the flowmeter accuracy is ±1.5%. When the waste heat fluid temperature is detected to be ≥60℃ and the flow rate is ≥7m³ / h, a switching signal is triggered. 3 When the flow rate is / h, the waste heat system is deemed available. The actuator of the intelligent switching control module uses an explosion-proof dual-way electric three-way valve. In green power mode, it connects the spiral tube assembly with the wind and solar power heating circuit, maintaining a tube-side flow velocity of 1.2m / s. In waste heat mode, it switches to the shell-side channel of the shell-and-tube heat exchanger, maintaining a tube-side flow velocity of 0.8m / s. When the ultrasonic sand collection chamber level gauge detects that the sand layer is >80% of its capacity, it forcibly switches to waste heat mode. The heat exchange parameters are automatically corrected according to the oil viscosity change, and the correction formula is as follows: Where Kp, Ki, and Kd are coefficients that are adjusted in real time according to viscosity, and e(t) is the deviation between the set temperature and the actual temperature.

[0011] Furthermore, the staggered-hole pretreatment sand removal system includes a fully enclosed cylinder, openings, a sand removal cavity, a double-barrel gate valve, and an inclined connecting pipe; the fully enclosed cylinder is located in the middle of the pipe, and the pipe has openings, with 12-16 openings per meter of pipe, the total area of ​​the openings accounting for 15%-20% of the pipe cross-sectional area, and the hole diameter d≥1.5d. max d maxTo accommodate the maximum sand particle diameter, openings are evenly distributed 360° around the pipe circumference, with 4 openings per ring, spaced 90° apart, and a ring spacing of 150-200mm. The opening axes of adjacent rings are staggered by 45°. The sand discharge chamber has a diameter Dc = 2.5 × pipe diameter, a conical bottom with a 60° cone angle, and is lined with a 15mm thick wear-resistant ceramic liner. The sand discharge chamber is equipped with a double-valve gate valve, with the main valve normally open and the backup valve used for maintenance isolation. An inclined connecting pipe is located between adjacent sand discharge chambers, with an inclination angle ≥ 5°, and a vent pipe is installed at the high position of the pipe. The sand discharge chambers converge into the main pipe through 4-8 branch pipes, with a flow velocity of 1.2-1.5m / s in the main pipe. The volume of the sand collection chamber is calculated according to the formula... The design features Q as the total flow rate and a residence time t ≥ 300 seconds. An internal guide cone disperses the fluid impact. When the sand discharge chamber level gauge detects a sand layer > 80%, the sand discharge valve automatically opens.

[0012] Furthermore, the upper part of the cyclone separation system is the liquid separation outlet, the middle part is the concentrated arrangement of cyclone sand removal core tubes, and the lower part is the particle collection chamber and sand discharge port. The cyclone sand removal core tube includes an outer shell and a ceramic cover installed on the outer shell. The ceramic cover includes a cyclone cone cover and a Venturi overflow pipe at the bottom. The internal flow field of the cyclone cone cover is a double volute inlet; the circumferential angle of the double volute inlet is 90°, and the area of ​​a single inlet is 1790 mm². 2 The inner diameter of the cyclone tube is 51mm, and the diameter of the volute is 60mm. The diameter of the volute is calculated according to the formula... Dynamic adjustment, where Dsc is the volute diameter, D is the inner diameter of the cyclone tube, Ain is the area of ​​a single inlet, and K is a correction coefficient, ranging from 0-5 mm considering the influence of fluid properties. When processing high-viscosity fluids, the volute diameter is increased by 5%-8%, and the inlet area is expanded by 10%-15%. During separation, the two fluid streams enter the double volute inlet symmetrically at a tangential angle of 15°-30°. The extension length of the Venturi slit overflow pipe is calculated according to the formula. In the design, L is the overflow pipe extension length, and D is the inner diameter of the vortex tube. ρ To input the liquid density, ρ 0 represents the density of water. A Venturi slit is formed on the Venturi overflow pipe. The length of the Venturi slit... The Venturi slit is 2-5mm from the bottom, and the tapering range of the Venturi slit is controlled to be 5-15mm by an adjustable wear-resistant bushing; the outer shell includes a lower cylinder and a conical section, and the diameter Dc of the gourd-shaped cavity at the end of the conical section is 1.8-2.2 times the bottom diameter Du of the cyclone tube, and a gas release port is provided.

[0013] Furthermore, the spiral annular superoleophilic modified sand collecting channel is located inside the conical section, including a superoleophilic surface and an oleophobic transition zone on the annular outer wall. The spiral helix angle β of the spiral annular superoleophilic modified sand collecting channel is 25°-35°, the channel width W is 0.1-0.15 times the cylinder diameter D, the number of spiral turns is adjusted according to the cylinder height, the stripe depth is 3-5cm, and the axial conveying speed of sand particles is maintained at 0.8-1.2m / s. The superoleophilic surface is sprayed on the inner wall of the channel, using a nano-silica or polydimethylsiloxane composite coating, with a coating thickness of 10-20μm and a contact angle <10°. After fluorination treatment, the contact angle is 5°-8°. The oleophobic transition zone on the annular outer wall is sprayed on the outer wall of the channel, using a perfluoroalkyl acrylate coating, with a contact angle >120°.

[0014] Furthermore, the heat exchanger tube multi-tube bundle integrated device adopts a modular design, and the components are connected through standardized interfaces.

[0015] Furthermore, the double volute inlet of the cyclone sand removal core tube works in conjunction with the Venturi slit overflow tube.

[0016] Furthermore, the multi-stage treatment system for sand-containing oil is adapted to space-constrained scenarios on offshore platforms and high-pressure environments in the deep sea.

[0017] Beneficial effects: (1) The green electricity heating heat exchange device uses green electricity such as offshore wind power and solar energy as energy sources, achieving zero carbon emissions. Compared with traditional heating methods that rely on fossil energy, it reduces energy cost expenditures and also reduces environmental pollution caused by energy use, thus having both economic and environmental benefits.

[0018] (2) The green electric heating heat exchange device achieves precise and stable preheating of sand-containing oil through the coordinated operation of the multi-tube bundle integrated device of heat exchange tubes, the spiral channel device inside the first heat exchange tube, the electric heat tracing device outside the heat exchange tube, and the first temperature detection and transmission device. The self-limiting electric heat tracing cable can automatically adjust the heating power according to the temperature to avoid local overheating; the spiral channel device inside the first heat exchange tube causes the oil to generate high-speed swirling flow, which enhances the collision between sand particles and oil molecules and effectively promotes particle pre-agglomeration.

[0019] (3) The waste heat recovery heat exchange device can effectively utilize the waste heat fluid and associated gas combustion heating seawater in the industrial production process as heat sources, converting waste heat and waste gas resources into energy for preheating sand-containing oil, realizing the secondary efficient utilization of energy, and reducing overall energy consumption and operating costs. The shell-and-tube heat exchanger adopts a counter-flow arrangement and baffle design, which keeps the low-temperature oil in the tube and the high-temperature heating fluid in the shell side at a large temperature difference, while increasing the disturbance and residence time of the heating fluid, thus improving the heat exchange efficiency; the spiral channel device in the internal second heat exchange tube makes the oil form a swirling flow, enhances the degree of turbulence inside the oil, further improves the heat exchange efficiency between the oil and the tube wall, and promotes the collision and aggregation of sand particles.

[0020] (4) The heat exchange tube staggered perforation sand removal device is designed with pipe perforation and cyclone separation coupling to achieve efficient sand removal in crude oil pretreatment. Its significance lies in upgrading the traditional single cyclone separation into a two-stage system of "pre-separation-fine separation". Through the pressure release of the perforated pipe, the staggered turbulence and the spiral vortex triple mechanism, the sand particles are directionally migrated to the sand removal chamber in advance, reducing the load on the cyclone separator.

[0021] (5) The intelligent switching control module integrates green electricity and waste heat resources to build an intelligent heat exchange system with "renewable energy priority + waste heat backup". The significance is to realize the energy cascade utilization and low-carbon upgrade, realize the millisecond-level dynamic switching of wind, solar and waste heat, and coordinate the control of dual-path electric three-way valve and variable frequency pump to avoid water hammer effect and maintain stable flow rate. It has the functions of material level linkage and viscosity adaptive adjustment.

[0022] (6) The cyclone fine separation system constructs a multi-stage enhanced separation system through the coordinated design of a double volute inlet, a Venturi slit overflow pipe, and a gourd-shaped underflow outlet. The double volute increases the tangential velocity, the Venturi slit improves the secondary separation efficiency for 1-10μm particles, and the gourd-shaped underflow suppresses backmixing. The dynamically adjustable slit width adapts to particles below 1000μm, improving processing capacity and significantly breaking through the separation limit of conventional cyclones.

[0023] (7) The Venturi slit recovery of the cyclone fine separation system reduces the pressure drop by 10-15%, and the overall energy consumption of the system is reduced by 20-30%. The self-cleaning function of the slit structure extends the continuous operation cycle by 3 times. The gourd-shaped underflow balances the internal and external pressure difference and avoids air lock blockage. This design remains stable under high sand content and high viscosity conditions, improving efficiency while achieving energy saving and consumption reduction.

[0024] (8) The spiral annular superoleophilic modified sand collection channel achieves efficient and selective oil-sand separation by controlling surface wettability and optimizing the flow field, reducing the residual oil rate of sand particles from 5%~8% to <2%. The channel width is optimized to induce secondary eddies, which prolongs the residence time of the oil phase and prevents sand particle accumulation. The superoleophilic coating preferentially captures oil film sand particles, and the combination with the nanocomposite coating achieves self-cleaning. The oleophobic transition zone on the outer wall forms a wettability gradient to drive the migration of the oil phase, thereby improving the overall separation efficiency and reducing energy consumption. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, 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:

[0026] Figure 1 This is a schematic diagram of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the green electric heating heat exchange device of the multi-stage treatment system for sand-containing oil that combines green electric energy and industrial waste heat, as described in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the spiral channel device inside the first heat exchange tube of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the waste heat recovery heat exchange device of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the spiral channel device inside the second heat exchange tube of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram of the pipe opening of the staggered hole pretreatment sand removal system of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0032] Figure 7 This is a schematic diagram of the cross-hole pretreatment sand removal system of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0033] Figure 8 This is a schematic diagram of the cyclone separation system of the multi-stage treatment system for sand-containing oil, which combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0034] Figure 9 This is a schematic diagram of the cyclone sand removal core tube of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0035] Figure 10 This is a schematic diagram of the ceramic cap of the cyclone sand removal core tube of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0036] Figure 11 This is a schematic diagram of the internal flow field model of the ceramic cap of the cyclone desanding core tube of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0037] Figure 12 This is a schematic diagram of the internal structure of the cyclone desanding core tube of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention.

[0038] Figure 13This is a schematic diagram of the spiral annular superoleophilic modified sand collection channel inside the conical section of the cyclone desanding core tube of the multi-stage treatment system for sand-containing oil that combines green electricity and industrial waste heat, as described in an embodiment of the present invention. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0040] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Example 1

[0042] See Figure 1-13 A multi-stage treatment system for sand-containing oil combining green electricity and industrial waste heat includes a dual-heat-source intelligent heating system, a staggered-hole pretreatment sand removal system, and a cyclone fine separation system. The dual-heat-source intelligent heating system includes a parallel green electricity heating heat exchanger 1 and a waste heat recovery heat exchanger 2, and the heating path is dynamically adjusted by an intelligent switching control module 4. The staggered-hole pretreatment sand removal system 3 is located between the heat exchanger and the cyclone separation system 5 to achieve pre-separation of sand particles. The cyclone fine separation system 5 is composed of multiple cyclone sand removal core tubes 5021, and a spiral annular super-oleophilic modified sand collection channel 6 is provided inside the cyclone sand removal core tubes 5021.

[0043] This embodiment adopts a three-level core architecture of "dual heat source intelligent heating - staggered hole pretreatment sand removal - cyclone fine separation", which is precisely matched to the space constraints of offshore platforms, the high pressure and low carbon requirements of deep sea, and solves the "volume-efficiency" contradiction of traditional equipment. It does not require a large amount of additional platform area and can be directly integrated into the existing offshore oil production system.

[0044] The dual heat source system in this embodiment uses a parallel design of green electricity (wind power and solar power) and industrial waste heat, combined with an intelligent switching module, to prioritize the use of green electricity to achieve zero carbon emissions, and to reserve waste heat to avoid energy waste. Compared with traditional single fossil energy heating equipment, the overall energy consumption is reduced by 25%-30%, which meets the requirements of low-carbon development of offshore oil fields.

[0045] Cost reduction and efficiency improvement in the separation process: The pretreatment sand removal system separates some sand particles in advance, reducing the load on the hydrocyclone fine separation system and avoiding frequent shutdowns of traditional equipment due to sand accumulation; the hydrocyclone desanding core tube has a built-in super-oleophilic channel to achieve efficient oil-sand separation, solving the problems of difficulty in capturing fine sand particles (1-10μm) and high residual oil rate (5%-8%) in traditional hydrocyclones, reducing subsequent sand particle treatment costs and improving crude oil recovery rate.

[0046] High operational stability: Each system module works together to adapt to the swaying and flow fluctuation conditions of the offshore platform. The dual heat source switching avoids system shutdown caused by a single heating failure. The combination of staggered hole sand discharge and cyclone fine separation reduces equipment blockage. The continuous operation cycle is extended by 3 times compared with traditional equipment, reducing the maintenance frequency and cost of the offshore platform.

[0047] In a specific example, the green electric heating heat exchange device 1 includes an external electric heat tracing device 101 for the heat exchange tubes, a first internal spiral channel device 102 for the first heat exchange tubes, a multi-tube bundle integrated device 103 for the heat exchange tubes, and a first temperature detection and transmission device 104. The external electric heat tracing device 101 uses a self-regulating heating tape made of high-molecular conductive plastic with a rectangular cross-section. It is tightly wound around the outside of the pipe of the first internal spiral channel device 102 for the first heat exchange tubes, with a winding spacing of 10-20mm. The power source is an offshore wind power generation device and a solar photovoltaic power generation device. The first internal spiral channel device 102 for the first heat exchange tubes includes 2-8 spiral blade units 105, and the thickness of the spiral blade unit 105 is 3-5mm. The tilt angle is 15°-30°, and the pitch is 2-5 times the pipe diameter. The heat exchange tube multi-tube bundle integrated device 103 is made of corrosion-resistant alloy steel and has multiple sets of positioning brackets 106 inside. The positioning brackets 106 have positioning holes that are adapted to the outer diameter of the heat exchange tubes for fixing 4-20 heat exchange tubes. The two ends of the heat exchange tube multi-tube bundle integrated device 103 are connected to the upstream and downstream pipelines through the first flange 107. The flange sealing surface uses a metal spiral wound gasket. The first temperature detection and transmitter device 104 uses a platinum resistance temperature sensor with a measurement accuracy of ±0.1℃. It is installed at the outlet of the heat exchange tube and has a built-in signal processing circuit to convert the resistance signal into a 4-20mA or 0-5V standard signal.

[0048] It should be noted that the green electric heating heat exchanger 1 in this embodiment is located at the downstream main outlet of the oil diversion device. Its main function is to couple the preheating of sand-containing oil with particle pre-agglomeration. This part consists of an external electric heating device 101 for the heat exchange tubes, a spiral channel device 102 for the heat exchange tubes, a multi-tube bundle integrated device 103 for the heat exchange tubes, and a temperature detection and transmission device 104. The oil inlet of the heat exchanger is connected to the downstream main outlet of the oil diversion device via a flange connection. After being distributed in the shell, the oil enters each heat exchange pipeline through the multi-tube bundle integrated device 103, ensuring good sealing performance and preventing oil leakage. The oil forms a swirling flow through the spiral channel devices 102 of each heat exchange tube and is preheated under the action of the external electric heating device 101. At the same time, the external temperature detection and transmission device 104 detects the flow downstream.

[0049] ① The main function of the external electric heat tracing device 101 is to preheat the oil as a heat exchanger. It uses a self-regulating electric heat tracing tape with a rectangular cross-section, made of high-molecular conductive plastic. This tape exhibits the characteristic that resistance increases with temperature and heating power automatically decreases, effectively preventing localized overheating. The electric heat tracing tape is tightly wrapped around the outside of the spiral channel pipe with a wrapping spacing of 10-20mm, ensuring uniform heat transfer to the sand-containing oil inside the pipe. Its power source is green electricity generated by offshore wind power and solar photovoltaic power generation devices. After rectification and voltage stabilization, the electricity is used to power the external electric heat tracing device.

[0050] ② The main function of the spiral channel device 102 inside the first heat exchange tube is to generate swirling motion of the oil inside the tube. Under the action of the pressure pump, the oil flows at a velocity of 0.5~1.5m / s through the multi-tube bundle integrated device and enters the multi-unit series spiral channel device of each heat exchange tube. The spiral channel device in each tube consists of 2~8 spiral blade units 105. The spiral blade units are made of stainless steel with a thickness of 3~5mm, and their tilt angle is designed between 15° and 30°, with a pitch of 2~5 times the tube diameter. This structural design ensures that when the oil flows inside the tube, it is not only subjected to the propulsive force along the axial direction of the pipe, but also to the tangential force generated by the spiral blades, thus forming a high-speed swirling motion. The swirling motion increases the turbulence inside the oil, greatly increasing the probability of collision between sand particles and oil molecules, creating favorable conditions for subsequent particle pre-agglomeration.

[0051] ③ The main function of the multi-tube bundle integrated heat exchanger device 103 is to connect the heat exchanger tubes in parallel to ensure structural stability and precise distribution and collection of oil flow. The main body of the device is made of high-strength, corrosion-resistant alloy steel, and internally has multiple sets of positioning supports 106. The supports have positioning holes adapted to the outer diameter of the heat exchanger tubes. Four to twenty heat exchanger tubes are fixed inside the device by welding or bolting, ensuring that each heat exchanger tube remains stable under high pressure and vibration conditions, preventing the oil flow and preheating effect from being affected by pipeline swaying. During the oil inflow stage, the oil flowing in from the oil distribution device is dispersed to each heat exchanger tube. During the oil outflow stage, the oil flowing out of each heat exchanger tube is collected and rectified, and the mixed oil enters the downstream pipeline with a stable flow rate and flow pattern. The two ends of the device are connected to the upstream and downstream pipelines through the first flange 107. The flange sealing surface uses a metal spiral wound gasket to effectively prevent oil leakage and the intrusion of external impurities. The multi-tube bundle integrated device adopts a modular design, and the components are connected through standardized interfaces, which facilitates rapid assembly and disassembly.

[0052] ④ The main function of the first temperature detection and transmission device 104 is to monitor the oil temperature in real time during the preheating process and transmit the temperature signal, providing an accurate basis for the temperature control of the entire system. This device uses a high-precision platinum resistance temperature sensor with a measurement accuracy of ±0.1℃, enabling it to quickly and accurately sense changes in oil temperature. The temperature sensor is installed at the outlet of the heat exchange tube to ensure that the collected data is the oil temperature after sufficient preheating. Its built-in signal processing circuit converts the resistance signal collected by the temperature sensor into a standard 4-20mA or 0-5V voltage signal, which is transmitted to the intelligent heating switching device via a shielded cable.

[0053] In a specific example, the waste heat recovery heat exchange device 2 includes a shell-and-tube heat exchanger 201, a second heat exchange tube internal spiral channel device 202, and a second temperature detection and transmission device 205. The shell-and-tube heat exchanger 201 is a cylindrical shell with multiple heat exchange tubes arranged inside to form the tube side. A baffle 204 is installed in the shell side. The baffle 204 has a segmental structure with a segmental ratio of 20%-40%. The tube side and shell side are arranged in a counter-current manner. The heating fluid is industrial waste heat fluid or seawater heated by associated gas combustion. When seawater is heated by associated gas combustion, a special filtration device and seawater circulation system are provided. Before the waste heat fluid is introduced, it is filtered for impurities and the flow rate is regulated. The two ends of the shell-and-tube heat exchanger 201 are connected to other pipelines through a second flange 206. The heat exchange tubes are fixed to the tube sheet 203 by expansion or welding.

[0054] It should be noted that the waste heat recovery heat exchanger 2 is located at the downstream secondary outlet of the oil diversion device. Its main function is to couple the preheating of sand-containing oil with particle pre-agglomeration, and it is connected in parallel with the green electric heating heat exchanger. This part consists of a shell-and-tube heat exchanger 201, a second heat exchange tube internal spiral channel device 202, and a second temperature detection and transmission device 205. The oil inlet of the heat exchanger is connected to the downstream secondary outlet of the oil diversion device via a flange connection. The oil forms a swirling flow after passing through the second heat exchange tube internal spiral channel device 202, and is preheated in the shell-and-tube heat exchanger 201. At the same time, the external second temperature detection and transmission device 205 detects the flow downstream.

[0055] ① The main function of the shell-and-tube heat exchanger 201 is to preheat the oil as a heat exchange device. The shell-and-tube heat exchanger consists of two parts: the tube side and the shell side. The tube side is used to transport the oil, and the shell side is used to flow the heating fluid. The shell-and-tube heat exchanger adopts a cylindrical shell, with multiple heat exchange tubes arranged inside to form the tube side. Tube sheets 203 are installed at both ends of the shell side. The heat exchange tubes are fixed to the tube sheets by expansion or welding to ensure the sealing of the tube side and shell side and prevent the two fluids from mixing. Baffles 204 are installed in the shell side. The baffles adopt a segmental structure with a segmental ratio controlled at 20%-40%. Their function is to guide the heating fluid to flow in a tortuous path in the shell side, increasing the degree of fluid turbulence and prolonging the residence time of the fluid in the shell side, thereby improving the heat exchange effect. The tube side and shell side are arranged in a counter-flow manner, that is, the oil flows into the tube side from one end of the heat exchanger, while the heating fluid flows into the shell side from the other end, and the two flow in opposite directions. This arrangement ensures a significant temperature difference between the low-temperature oil inside the tubes and the high-temperature heating fluid in the shell throughout the heat exchange process. Compared to a co-current arrangement, a counter-current arrangement can improve heat exchange efficiency by 30%-50%, ensuring the oil can fully absorb heat and complete preheating. The heating fluid is either waste heat or seawater heated by associated gas combustion. When using associated gas combustion to heat seawater, a dedicated filtration device and seawater circulation system are installed to prevent impurities in the seawater from clogging the heat exchanger. The waste heat fluid is introduced through pipelines from waste heat generation equipment in the industrial production process, and undergoes impurity filtration and flow regulation before introduction. Both ends of the device are connected to other pipelines via a second flange 206.

[0056] ②The main function of the spiral channel device 201 inside the heat exchange tube is to generate swirling motion of the oil inside the tube. Consistent with the green electric heating heat exchange device, it is installed inside the heat exchange tube. The swirling motion increases the turbulence inside the oil, creating favorable conditions for heat exchange and improving the heat exchange efficiency between the oil and the tube wall.

[0057] ③ The main function of the second temperature detection and transmission device 205 is to monitor the temperature of the oil in real time during the preheating process and transmit the temperature signal to provide an accurate basis for the temperature control of the entire system.

[0058] In a specific example, the intelligent switching control module 4 is based on PLC control and includes a wind and solar power monitoring unit and a waste heat source monitoring unit. The wind and solar power monitoring unit uses a Hall effect sensor and an ultrasonic anemometer to monitor the output power of wind and solar power in real time with an accuracy of ±1%. When the power is <30% of the rated value, a switching signal is triggered. The waste heat source monitoring unit uses a K-type shell-side thermocouple and an electromagnetic flow meter. The thermocouple accuracy is ±0.5℃, and the flow meter accuracy is ±1.5%. When the waste heat fluid temperature is detected to be ≥60℃ and the flow rate is ≥7m³ / h, a switching signal is triggered. 3When the flow rate is / h, the waste heat system is deemed available; the actuator of the intelligent switching control module 4 uses an explosion-proof dual-way electric three-way valve. In green power mode, it connects the spiral tube assembly with the wind and solar power heating circuit, maintaining a tube-side flow velocity of 1.2m / s. In waste heat mode, it switches to the shell-side channel 201 of the shell-and-tube heat exchanger, maintaining a tube-side flow velocity of 0.8m / s. When the ultrasonic sand collection chamber level gauge detects that the sand layer is >80% of its capacity, it forcibly switches to waste heat mode. The heat exchange parameters are automatically corrected according to the change in oil viscosity, and the correction formula is: Where Kp, Ki, and Kd are coefficients that are adjusted in real time according to viscosity, and e(t) is the deviation between the set temperature and the actual temperature.

[0059] It should be noted that in this embodiment, an intelligent switching control module 4 is added between the green electricity heating module which uses renewable energy power supply and the shell-and-tube waste heat exchange module. Based on the monitoring and prediction of the portion of wind and solar power that can be utilized, the two heat exchange devices are intelligently switched.

[0060] ① During the daytime when wind and solar power are abundant, green electricity is prioritized. When sufficient wind and solar power is detected, the PLC outputs the following command: open the three-way valve of the green electricity circuit and close the waste heat circuit. Start the variable frequency pump of the spiral tube assembly to the set speed. The wind and solar power monitoring unit utilizes sensors such as Hall effect sensors and ultrasonic anemometers to monitor the output power of wind and solar power in real time with an accuracy of ±1%. When the power is less than 30% of the rated value, a switching signal is triggered.

[0061] ② When green electricity is insufficient at night or on cloudy days, backup waste heat is used. If the wind and solar power output remains below 10kW for 5 minutes, the PLC gradually reduces the green power pump speed. To avoid water hammer, the waste heat valve is opened slowly, and the seawater flow rate is adjusted via feedback from the shell-side thermocouple to maintain stable oil temperature. The waste heat source monitoring unit uses a K-type shell-side thermocouple with an accuracy of ±0.5℃ and an electromagnetic flow meter with an accuracy of ±1.5% to detect waste heat fluid temperatures ≥60℃ and flow rates ≥7m³ / h to determine the availability of the waste heat system.

[0062] ③ The actuator utilizes an explosion-proof dual-way electric three-way valve to switch the fluid path and automatically adjust the flow rate according to the control signal. In green electricity mode, it connects the spiral tube assembly with the wind and solar power heating circuit, maintaining a tube-side flow velocity of 1.2 m / s. In waste heat mode, it switches to the shell-side channel of the shell-and-tube heat exchanger, operating at an energy-saving low speed of 0.8 m / s. When the ultrasonic sand collection chamber level gauge detects that the sand layer is >80% of its capacity, it forcibly switches to waste heat mode to avoid a sudden temperature drop caused by sand discharge during green electricity heating. The heat exchange parameters are automatically corrected based on changes in oil viscosity.

[0063]

[0064] Where Kp, Ki, and Kd are coefficients that are adjusted in real time based on viscosity, and e(t) is the deviation between the set temperature and the actual temperature.

[0065] In a specific example, the staggered-hole pretreatment sand removal system 3 includes a fully enclosed cylinder 301, openings 302, a sand removal cavity 303, a double-barrel gate valve 304, and an inclined connecting pipe 305; the fully enclosed cylinder 301 is located in the middle of the pipe, and openings 302 are provided on the pipe, with 12-16 openings 302 per meter of pipe, the total area of ​​the openings 302 accounting for 15%-20% of the pipe cross-sectional area, and the diameter d ≥ 1.5d. max d max To accommodate the maximum sand particle diameter, openings 302 are evenly distributed 360° around the pipe circumference, with 4 openings per ring, spaced 90° apart, and a ring spacing of 150-200mm. The axes of openings 302 in adjacent rings are staggered by 45°. The sand discharge chamber 303 has a diameter Dc = 2.5 × pipe diameter, a conical bottom with a cone angle of 60°, and is lined with a 15mm thick wear-resistant ceramic liner. The sand discharge chamber 303 is equipped with a double-valve gate valve 304, in which the main valve is normally open and the backup valve is used for maintenance isolation. The inclined connecting pipe 305 is located between adjacent sand discharge chambers 303, with an inclination angle ≥5°, and a vent pipe is provided at the high position of the pipe. The sand discharge chamber 303 merges into the main pipe through 4-8 branch pipes, with a flow velocity of 1.2-1.5m / s in the main pipe. The volume of the sand collection chamber is calculated according to the formula. The design features Q as the total flow rate and a residence time t ≥ 300 seconds. An internal guide cone is installed to disperse fluid impact. When the 303 level gauge in the sand discharge chamber detects a sand layer > 80%, the sand discharge valve is automatically opened.

[0066] It should be noted that before the crude oil enters the cyclone separator through the pipeline after heat exchange, a fully enclosed cylinder 301 is added in the middle of the pipeline, and holes 302 are opened on the pipeline and arranged in an alternating manner to allow the sand-containing crude oil to flow out and collect the sand and gravel in the cavity 303 at the bottom.

[0067] ① 12-16 openings are installed per meter of pipe, with the total area of ​​the openings accounting for 15%-20% of the pipe cross-sectional area, ensuring flow velocity fluctuation <10%, and the opening diameter d ≥ 1.5d. max d max To accommodate the maximum sand particle diameter, perforations are evenly distributed 360° around the pipe circumference, with four per ring, spaced 90° apart, and a ring spacing of 150-200mm. These perforations are staggered, with a 45° difference in the angle between adjacent rows. The annular perforations release local pressure, inducing radial diffusion of the sand-laden liquid and preventing sand particles from depositing at the bottom of the pipe. The staggered perforation structure features an axial staggered angle: the axes of the perforations in adjacent rings are staggered by 45°. This staggered layout disrupts the directional movement trajectory of the sand particles, forcing them to tumble and mix. The helical angle generates eddies, increasing sand particle suspension and improving the uniformity of sand concentration distribution by 40%.

[0068] ② The sand discharge chamber is matched with valve 304. The sand discharge chamber has a diameter Dc = 2.5 × pipe diameter and a conical bottom with a cone angle of 60°. It is equipped with a wear-resistant ceramic liner with a thickness of 15mm. The valve is a double knife gate valve. The main valve is normally open and the standby valve is for maintenance isolation. The chamber is expanded to reduce the flow rate, with a flow velocity of 0.3~0.5m / s, and the sand particles settle due to gravity. The valve has double insurance to prevent leakage.

[0069] ③ An inclined connecting pipe 305 with an inclination angle ≥5° is installed between adjacent sand discharge chambers. A vent pipe is installed at the high position of the pipe to prevent air blockage. The pressure difference drives the sand particles to migrate to the sand collection chamber. The inclined design achieves gravity-flow sand discharge and reduces the risk of pipe blockage. ④ 4~8 branch pipes converge into the main pipe, with a flow velocity of 1.2~1.5m / s. Sand collection chamber volume:

[0070]

[0071] Where Q is the total flow rate, the residence time t ≥ 300 seconds, and an internal guide cone disperses the fluid impact. Multiple branch pipes dissipate energy through counter-current flow within the sand collection chamber, increasing sand settling efficiency by 25%; the guide cone eliminates vortex disturbances. After heat exchange, the fluid enters the orifice pipe, and the pressure release at the orifice causes sand particles to migrate towards the orifice area. Turbulent disturbances are generated by the staggered orifices, and the sand particles slide into the sand discharge chamber for temporary storage along with the connecting pipe. The main flow continues to the cyclone separator, where the sand particles are discharged uniformly through the sand collection chamber. When the chamber level gauge detects a sand layer > 80%, the sand discharge valve automatically opens.

[0072] In a specific example, the upper part of the cyclone separation system 5 is the liquid separation outlet 501, the middle part is the concentrated arrangement section of the cyclone sand removal core tubes 502, and the lower part is the particle collection chamber 503 and the sand discharge port 504. The cyclone sand removal core tube 5021 includes a shell and a ceramic cover installed on the shell. The ceramic cover includes a cyclone cone cover 5022 and a venturi overflow pipe 5026 at the bottom. The internal flow field of the cyclone cone cover 5022 is a double volute inlet 5025. The double volute inlet 5025 has an circumferential angle of 90° and a single inlet area of ​​1790 mm². 2 The inner diameter of the cyclone tube is 51mm, and the diameter of the volute is 60mm. The diameter of the volute is calculated according to the formula... Dynamic adjustment, where Dsc is the volute diameter, D is the inner diameter of the cyclone tube, Ain is the area of ​​a single inlet, and K is a correction coefficient, ranging from 0-5 mm considering the influence of fluid properties. When processing high-viscosity fluids, the volute diameter increases by 5%-8%, and the inlet area increases by 10%-15%. During separation, the two fluid streams enter the double volute inlet 5025 symmetrically at a tangential angle of 15°-30°. The extension length of the Venturi slit overflow pipe 5026 is calculated according to the formula. In the design, L is the overflow pipe extension length, and D is the inner diameter of the vortex tube. ρ To input the liquid density, ρ0 represents the density of water. A Venturi slit 5027 is formed on the Venturi slit overflow pipe 5026. The length of the Venturi slit 5027 is... The Venturi slit 5027 is 2-5mm from the bottom, and the tapering range of the Venturi slit 5027 is controlled within 5-15mm by an adjustable wear-resistant bushing; the outer shell includes a lower cylindrical body 5023 and a conical section 5024. The end of the conical section 5024 is provided with a gourd-shaped cavity 5028 with a cavity diameter Dc that is 1.8-2.2 times the bottom diameter Du of the cyclone tube, and a gas release port is provided.

[0073] It should be noted that the liquid-solid separation principle of the cyclone separation system is based on the dynamic process of centrifugal sedimentation, achieving efficient separation of the solid and liquid phases through fluid dynamics design. The overall cyclone separation system consists of several cyclone desanding core tubes. The upper part is the liquid discharge outlet 501 after separation, the middle part is the concentrated arrangement section of the cyclone desanding core tubes 502, and the lower part is the particle collection chamber 503 and the desanding outlet 504. Each individual cyclone core tube 5021 mainly consists of a cyclone cone cover 5022 and a lower cylinder 5023 and a conical section 5024 inside the shell.

[0074] ① The inlet section is a volute-type double-inlet 5025 with an circumferential angle of 90° and a single inlet area of ​​1790 mm². The inner diameter of the cyclone tube is 51 mm, and the diameter of the volute is 60 mm. The volute diameter can be dynamically adjusted based on the inlet area and the inner diameter of the cyclone tube, using the following formula:

[0075]

[0076] Where Dsc is the volute diameter, D is the inner diameter of the vortex tube, Ain is the area of ​​a single inlet, and K is a correction coefficient, ranging from 0 to 5 mm considering the influence of fluid properties. Adjustments should be made according to actual conditions for different operating situations; for example, for high-viscosity fluids, the volute diameter needs to be increased by 5-8%, and the inlet area increased by 10-15%. During separation, the two fluid streams enter the volute cavity symmetrically at a tangential angle of 15° to 30°, forming a superimposed rotating flow field under the guiding effect of the volute. This double-helix inflow method can increase the tangential velocity by 20-30%, significantly enhancing the centrifugal force field intensity. The two inflows form coupled vortices with a phase difference of approximately 90° within the volute cavity, generating a more stable forced vortex core region.

[0077] ② The overall insertion length of the overflow pipe 5026 is 56mm. The optimal length is selected based on the inner diameter of different vortex tube cylinders, determined by the following formula:

[0078]

[0079] Where L is the overflow pipe extension length, D is the inner diameter of the cyclone tube, ρ is the input liquid density, and ρ0 is the density of water. A slit is made in the overflow pipe, with the slit direction (5027) opposite to the direction of fluid rotation within the cylinder. This effectively improves separation efficiency and enhances secondary centrifugation. The Venturi slit's contraction-expansion structure creates a local high-speed flow field at the overflow pipe inlet, increasing the flow velocity by 30-50% and generating stronger centrifugal force. This achieves secondary separation of fine particles (1-10 μm), improving efficiency by 15-20% compared to traditional straight-cylinder overflow pipes. The expansion section (diffusion angle 8°-12°) effectively recovers kinetic energy, reducing system pressure drop by 10-15%. Combined with the gourd-shaped underflow inlet design, overall energy consumption is reduced by 20-30% compared to traditional cyclones. The slit structure, by adjusting the airflow contraction ratio (recommended 1.5:1-2:1), can suppress air column pulsation, reduce particle backmixing, and reduce underflow oil content to <3%. The slits effectively prevent clogging. High-speed fluid flowing through the venturi slits (>6 m / s) can flush the pipe wall, preventing particle deposition and extending the continuous operating cycle by more than three times, achieving a self-cleaning effect. Furthermore, the dynamic slit width can be adjusted, with the tapering range controlled between 5 and 15 mm via an adjustable wear-resistant bushing. This allows for the handling of fluids containing sand particles up to 1000 μm in diameter, effectively improving the separation efficiency of large particles. The optimal relationship between the slit length and the overflow pipe insertion length is as follows:

[0080]

[0081] Suitable for separating crude oil containing fine particles, the synergistic design of the dual volute inlet and venturi slot increases processing capacity by 40% compared to a single inlet design. The slot should be opened at a certain distance from the bottom, 2-5mm. ③ The underflow outlet is equipped with a gourd-shaped cavity 5028, with an optimized ratio of cavity diameter Dc to cyclone tube bottom diameter Du.

[0082]

[0083] The circular cavity, serving as the terminal settling zone in the cyclone separation process, provides expanded space for the separated solid particles, avoiding flow field disturbances caused by direct sand discharge from the bottom of the cone. By increasing the volume (typically 1.5 to 2 times the diameter of the cone bottom), the particle velocity is reduced, promoting further settling and enrichment of the sand particles. The geometric symmetry of the cavity suppresses bottom eddies, reducing the risk of secondary entrainment of separated particles, and lowering the backmixing rate to <5%, resulting in a more stable flow field. Combined with the gourd-shaped cavity design, and connected to a cylindrical cavity with the same diameter as the underflow outlet, a staged control system of settling before discharge is formed, preventing clean liquid from mixing into the underflow. The cavity volume design must meet the temporary storage requirements under maximum particle load, ensuring continuous discharge of high-concentration sand particles without clogging. As a pressure buffer, the cavity balances the internal and external pressure difference through the gas release port, preventing airlock effects from affecting sand discharge. A well-designed cavity can reduce system pressure drop by 10-15%.

[0084] In a specific example, the spiral annular superoleophilic modified sand collecting channel 6 is located inside the conical section 5024, including a superoleophilic surface 601 and an annular outer wall oleophobic transition zone 602; the spiral annular superoleophilic modified sand collecting channel 6 has a helix angle β = 25°-35°, a channel width W is 0.1-0.15 times the cylinder diameter D, the number of spiral turns is adjusted according to the cylinder height, the stripe depth is 3-5cm, and the axial conveying speed of sand particles is maintained at 0.8-1.2m / s; the superoleophilic surface 601 is sprayed on the inner wall of the channel, using a nano-silica or polydimethylsiloxane composite coating, with a coating thickness of 10-20μm and a contact angle <10°, which becomes 5°-8° after fluorination treatment; the annular outer wall oleophobic transition zone 602 is sprayed on the outer wall of the channel, using a perfluoroalkyl acrylate coating, with a contact angle >120°.

[0085] It should be noted that the conical section of the liquid-solid cyclone separator is equipped with a spiral annular superoleophilic modified sand collection channel 6, the core function of which is to achieve selective oil-sand separation through surface wettability control and flow field synergistic optimization.

[0086] ① The helix angle β is 25°~35°, which is the optimal solution for balancing centrifugal force and axial thrust. When β=30°, the axial velocity component allows sand particles to be transported downwards at a suitable speed, avoiding deposition and blockage; at the same time, it effectively induces secondary eddies, prolonging the residence time of the oil phase and creating more sufficient time conditions for oil-sand separation. Through precise angle design, it ensures smooth discharge of the solid phase and enhances the oil phase separation effect, enabling the equipment to operate stably under different fluid viscosity conditions without frequent adjustments to structural parameters, thus improving the equipment's versatility and stability. The width W of the annular channel is 0.1~0.15 times the cylinder diameter D. By optimizing the width ratio, the separation performance is significantly improved without increasing the overall size of the equipment. Compared with traditional structures, it can increase the oil droplet coalescence rate, reducing the difficulty and cost of subsequent oil phase treatment. The number of helical turns is increased or decreased according to different cylinder heights, and the stripe depth is 3~5cm. Flexibly adjusting the number of helical turns according to the cylinder height ensures that different specifications of hydrocyclones can achieve the best separation effect. For taller cylinders, increasing the number of spiral turns can extend the fluid path within the channel, further enhancing the separation process. Conversely, for shorter cylinders, appropriately reducing the number of turns can avoid unnecessary resistance losses. At the same time, the spiral flow channel maintains an axial transport velocity of approximately 0.8~1.2 m / s for the sand particles, preventing sand particles from accumulating and clogging within the channel.

[0087] ② The superoleophilic surface 601 preferentially captures sand particles wrapped in oil film through molecular adsorption, forming a continuous liquid film of oil phase on the wall surface, while hydrophilic particles continue to settle towards the wall surface under centrifugal force, achieving selective separation of oil and sand and significantly reducing the residual oil rate on the sand particle surface. The contact angle of the superoleophilic modified surface is <10°, and it preferentially captures sand particles wrapped in oil film through molecular adsorption, forming a continuous liquid film of oil phase on the channel wall surface, while hydrophilic particles continue to settle towards the wall surface under centrifugal force. This design can reduce the residual oil rate on the sand particle surface from 5-8% in conventional separation to <2%. The spiral annular structure extends the residence time of the oil phase by about 30% through secondary vortex, while maintaining the axial transport speed of sand particles, avoiding sand particle accumulation, and optimizing flow resistance. The low adhesion workability of the superoleophilic surface makes it difficult for heavy oil components to deposit, and combined with the shearing effect of the spiral flow channel, continuous self-cleaning can be achieved. The superoleophilic layer is made of nano-silica or polydimethylsiloxane composite coating with a thickness of 10~20μm. The surface forms a micron-nano-scale rough structure. Combined with the low surface energy characteristics, it can still maintain stable superoleophilic properties under the scouring of sand-containing fluids. Its service life is 2~3 times longer than that of conventional coatings. After fluorination treatment, the contact angle can reach 5°~8°.

[0088] ③ The 602 oleophobic transition zone on the outer ring wall is coated with perfluoroalkyl acrylate, with a contact angle >120°, forming a wettability gradient and driving the oil phase to migrate inward.

[0089] In a specific example, the heat exchange tube multi-tube bundle integrated device 103 adopts a modular design, and the components are connected through standardized interfaces.

[0090] In this embodiment, each heat exchange tube can be disassembled and replaced independently, and maintenance does not require a complete shutdown, reducing maintenance time by more than 60% compared to traditional integrated structures.

[0091] In a specific example, the double volute inlet 5025 of the cyclone desanding core tube works in conjunction with the Venturi slot overflow tube (5026).

[0092] The synergistic effect of this embodiment increases the processing capacity of the hydrocyclone separation system 5 by 40% compared to the single-inlet hydrocyclone structure, improves the separation efficiency of 1-10μm fine particles by 15-20%, and reduces the overall system pressure drop by 10-15% compared to the traditional hydrocyclone.

[0093] In a specific example, the sand-containing oil multi-stage treatment system is adapted to the space-constrained scenarios of offshore platforms and the high-pressure environment of the deep sea.

[0094] This embodiment reduces the floor space by 30%-40% compared to traditional sand-containing oil treatment systems by using a compact swirl core tube and multi-tube converging technology; when the green electricity ratio is ≥50%, the carbon emissions per ton of oil treated are reduced by more than 40% compared to traditional single heat source systems, the residual oil rate of sand particles is reduced from 5%-8% to <2%, and the continuous operation cycle is extended by 3 times compared to traditional equipment.

[0095] In its implementation, when sand-laden crude oil enters the multi-tube bundle integrated heat exchanger 103 (corrosion-resistant alloy steel) through the inlet, it is diverted to 20 parallel heat exchanger tubes. Each tube is equipped with a spiral vane unit 105, causing the oil to swirl at a flow rate of 1.2 m / s. A self-limiting heating cable is tightly wrapped around the outside of the tube, powered by wind and solar energy, raising the oil temperature from 10℃ to 60℃. A platinum resistance temperature sensor at the outlet monitors the oil temperature in real time and outputs a signal to the PLC. The intelligent switching control module monitors the wind and solar energy: if the Hall sensor detects that the wind and solar power is <10kW for 5 minutes, the PLC activates the waste heat mode. When the crude oil viscosity increases from 10 mPa·s to 30 mPa·s, the heating parameters are dynamically adjusted. When the ultrasonic level gauge detects that the sand layer in the cavity is >80%, the system automatically switches to waste heat mode (to avoid temperature drop during green electricity sand discharge). When wind and solar power are insufficient, the PLC switches to shell-and-tube heat exchanger 201: 80℃ industrial waste heat fluid is introduced into the shell side, flowing in a tortuous manner through baffle 204; crude oil flows counter-currently through the spiral channel device 202 inside the second heat exchange tube, reaching a temperature of 55℃ after heat exchange. Preheated oil enters the perforated pipe 301, inducing sand particles to migrate radially to the sand discharge chamber 303. The double-barrel gate valve 304 is normally open, with the standby valve isolated for maintenance; the inclined connecting pipe 305 connects adjacent chambers, and the high-level vent pipe prevents air blockage. Pretreated oil enters the cyclone sand removal core tube 5021 and the double volute inlet 5025, where two tangential flows form a superimposed vortex, increasing the tangential velocity by 28%. Fine particle separation efficiency is increased by 18%. Collected at the gourd-shaped underflow outlet, the backmixing rate is <4%. Super-oleophilic channel ( Figure 10-11 The inner wall nano-SiO2 coating preferentially adsorbs oil film sand particles; the outer wall perfluoroalkyl acrylate coating drives the oil phase to migrate inward, extending the oil phase residence time by 32%.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-stage treatment system for sand-containing oily fluids that combines green electricity and industrial waste heat, characterized in that, It includes a dual-heat-source intelligent heating system, a staggered-hole pretreatment sand removal system, and a cyclone fine separation system; the dual-heat-source intelligent heating system includes a parallel green electric heating heat exchange device (1) and a waste heat recovery heat exchange device (2), and the heating path is dynamically adjusted by an intelligent switching control module (4); the staggered-hole pretreatment sand removal system (3) is located between the heat exchange device and the cyclone fine separation system (5) to achieve sand pre-separation; the cyclone fine separation system (5) is composed of multiple cyclone sand removal core tubes (5021), the cyclone sand removal core tubes (5021) A spiral annular super-oleophilic modified sand collection channel (6) is set inside the 5021. The staggered hole pretreatment sand discharge system (3) includes a fully enclosed cylinder (301), an opening (302), a sand discharge cavity (303), a double knife gate valve (304), and an inclined connecting pipe (305). The fully enclosed cylinder (301) is located in the middle of the pipe, and an opening (302) is opened on the pipe. 12-16 openings (302) are set per meter of pipe. The total area of ​​the openings (302) accounts for 15%-20% of the pipe cross-sectional area, and the hole diameter d≥1.5d. max d max To accommodate the maximum sand particle diameter, openings (302) are evenly distributed 360° around the pipe circumference, with 4 openings per ring, spaced 90° apart, and the ring spacing is 150-200mm. The axes of the openings (302) in adjacent rings are staggered by 45°. The bottom of the sand discharge chamber (303) is a conical structure with a cone angle of 60°, lined with a 15mm thick wear-resistant ceramic liner. The sand discharge chamber (303) is equipped with a double-ended knife gate valve (304), in which the main valve is normally open and the standby valve is used for maintenance isolation. The inclined connecting pipe (305) is located between adjacent fully enclosed cylinders (301), with an inclination angle ≥5°. A vent pipe is provided at the high position of the pipe. The inclined connecting pipe (305) merges into the main pipe, with a flow velocity of 1.2-1.5m / s in the main pipe. The volume of the sand collection chamber is calculated according to the formula. The design is as follows: Q is the total flow rate, the residence time t≥300 seconds, and the internal guide cone is set to disperse the fluid impact; when the sand discharge chamber (303) level gauge detects that the sand layer is >80%, the sand discharge valve is automatically opened.

2. The multi-stage treatment system for sand-containing oil fluid combining green electricity and industrial waste heat according to claim 1, characterized in that, The green electric heating heat exchange device (1) includes an external electric heat tracing device (101) for the heat exchange tube, a first internal spiral channel device (102) for the heat exchange tube, a multi-tube bundle integrated device (103) for the heat exchange tube, and a first temperature detection and transmission device (104). The external electric heat tracing device (101) for the heat exchange tube uses a self-regulating electric heat tracing tape, which is made of high-molecular conductive plastic with a rectangular cross-section. It is tightly wound around the outside of the pipe of the first internal spiral channel device (102) for the heat exchange tube, with a winding spacing of 10-20mm. The power source is the offshore wind power generation device and the solar photovoltaic power generation device. The first internal spiral channel device (102) for the heat exchange tube includes 2-8 spiral blade units (105), and the thickness of the spiral blade unit (105) is 3-5mm. The oblique angle is 15°-30°, and the pitch is 2-5 times the pipe diameter; the heat exchange tube multi-tube bundle integrated device (103) is made of corrosion-resistant alloy steel and has multiple sets of positioning brackets (106) inside. The positioning brackets (106) are provided with positioning holes that are adapted to the outer diameter of the heat exchange tubes for fixing 4-20 heat exchange tubes. The two ends of the heat exchange tube multi-tube bundle integrated device (103) are connected to the upstream and downstream pipelines through the first flange (107). The flange sealing surface is made of metal spiral wound gasket; the first temperature detection and transmitter device (104) is made of platinum resistance temperature sensor with a measurement accuracy of ±0.1℃. It is installed at the outlet of the heat exchange tube and has a built-in signal processing circuit for converting the resistance signal into a 4-20mA or 0-5V standard signal.

3. The multi-stage treatment system for sand-containing oil fluid combining green electricity and industrial waste heat according to claim 1, characterized in that, The waste heat recovery heat exchange device (2) includes a shell-and-tube heat exchanger (201), a second heat exchange tube internal spiral channel device (202), and a second temperature detection and transmission device (205). The shell-and-tube heat exchanger (201) is a cylindrical shell with multiple heat exchange tubes arranged inside to form the tube side. A baffle plate (204) is installed in the shell side. The baffle plate (204) has a circular segment structure with a segment ratio of 20%-40%. The tube side and shell side are arranged in a counter-current manner. The heating fluid is industrial waste heat fluid or seawater heated by associated gas combustion. When associated gas combustion is used to heat seawater, a special filtration device and seawater circulation system are provided. Before the waste heat fluid is introduced, it is filtered for impurities and the flow rate is adjusted. The two ends of the shell-and-tube heat exchanger (201) are connected to other pipelines through the second flange (206). The heat exchange tubes are fixed on the tube sheet (203) by expansion or welding.

4. The multi-stage treatment system for sand-containing oil fluid combining green electricity and industrial waste heat according to claim 3, characterized in that, The intelligent switching control module (4) is based on PLC control and includes a wind and solar power monitoring unit and a waste heat source monitoring unit. The wind and solar power monitoring unit uses a Hall effect sensor and an ultrasonic anemometer to monitor the output power of wind and solar power in real time with an accuracy of ±1%. When the power is <30% of the rated value, a switching signal is triggered. The waste heat source monitoring unit uses a K-type shell-side thermocouple and an electromagnetic flow meter. The thermocouple accuracy is ±0.5℃ and the flow meter accuracy is ±1.5%. When the waste heat fluid temperature is detected to be ≥60℃ and the flow rate is ≥7m³, a switching signal is triggered. 3 When / h, the waste heat system is deemed available; the actuator of the intelligent switching control module (4) adopts an explosion-proof dual-way electric three-way valve. In green power mode, it connects the spiral tube group with the wind and solar heating circuit, maintaining a tube flow velocity of 1.2m / s. In waste heat mode, it switches to the shell-side channel of the shell-and-tube heat exchanger (201), maintaining a tube flow velocity of 0.8m / s. When the ultrasonic sand collection chamber level gauge detects that the sand layer is >80% of the capacity, it forces a switch to waste heat mode. The heat exchange parameters are automatically corrected according to the change in oil viscosity. The correction formula is as follows: Where Kp, Ki, and Kd are coefficients that are adjusted in real time according to viscosity, and e(t) is the deviation between the set temperature and the actual temperature.

5. The multi-stage treatment system for sand-containing oil fluid combining green electricity and industrial waste heat according to claim 1, characterized in that, The cyclone fine separation system (5) has a liquid separation outlet (501) at the top, a concentrated arrangement section (502) of cyclone sand removal core tubes in the middle, and a particle collection chamber (503) and sand discharge port (504) at the bottom. The cyclone sand removal core tube (5021) includes an outer shell and a ceramic cover installed on the outer shell. The ceramic cover includes a cyclone cone cover (5022) and a Venturi overflow pipe (5026) at the bottom. The internal flow field of the cyclone cone cover (5022) is a double volute inlet (5025). The double volute inlet (5025) has an circumferential angle of 90° and a single inlet area of ​​1790 mm². 2 The inner diameter of the cyclone tube cylinder is 51mm, and the diameter of the volute is 60mm. When separation is performed, the two fluids enter the double volute inlet (5025) symmetrically at a tangential angle of 15°-30°. The Venturi slit overflow pipe (5026) is provided with a Venturi slit (5027), which is 2-5mm from the bottom. The tapering range of the Venturi slit (5027) is controlled at 5-15mm by an adjustable wear-resistant bushing. The outer shell includes a lower cylinder (5023) and a conical section (5024). The end of the conical section (5024) is provided with a gourd-shaped cavity (5028) with a cavity diameter Dc that is 1.8-2.2 times the bottom diameter Du of the cyclone tube, and a gas release port is provided.

6. The multi-stage treatment system for sand-containing oil fluid combining green electricity and industrial waste heat according to claim 5, characterized in that, The spiral annular super-oleophilic modified sand collection channel (6) is located inside the conical section (5024) and includes a super-oleophilic surface (601) and an oleophobic transition zone (602) on the annular outer wall. The spiral angle β of the spiral annular super-oleophilic modified sand collection channel (6) is 25°-35°, the number of spiral turns is adjusted according to the height of the cylinder, the stripe depth is 3-5cm, and the axial conveying speed of the sand particles is maintained at 0.8-1.2m / s. The super-oleophilic surface (601) is sprayed on the inner wall of the channel and is coated with nano-silica or polydimethylsiloxane composite coating. The coating thickness is 10-20μm and the contact angle is <10°. After fluorination treatment, the contact angle is 5°-8°. The oleophobic transition zone (602) on the annular outer wall is sprayed on the outer wall of the channel and is coated with perfluoroalkyl acrylate coating. The contact angle is >120°.

7. The multi-stage treatment system for sand-containing oil fluid combining green electricity and industrial waste heat according to claim 2, characterized in that, The heat exchange tube multi-tube bundle integrated device (103) adopts a modular design, and the components are connected through standardized interfaces.

8. The multi-stage treatment system for sand-containing oil fluid combining green electricity and industrial waste heat according to claim 5, characterized in that, The double volute inlet (5025) of the cyclone sand removal core tube works in conjunction with the Venturi slot overflow pipe (5026).

9. The multi-stage treatment system for sand-containing oil fluids combining green electricity and industrial waste heat according to any one of claims 1-8, characterized in that, The multi-stage treatment system for sand-containing oil is suitable for space-constrained scenarios on offshore platforms and high-pressure environments in the deep sea.

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