Crude oil pretreatment apparatus and method

Abstract

This invention discloses a crude oil pretreatment device and method. The device includes: a static mixing unit that receives crude oil after sedimentation and separation and injects magnetic seeds and flocculants; a magnetic separation unit, which is a cylindrical structure with multiple layers of magnetically coagulating media inside. Under the action of a gradient magnetic field, the multiple layers of magnetically coagulating media adsorb flocculated precipitates in the crude oil with magnetic seeds as the core; and an oil-water deep separation unit, which has multiple layers of annularly spaced electrode plates and coalescing packing. This oil-water deep separation unit receives the magnetically separated crude oil, and the crude oil flows sequentially through the multiple layers of coalescing packing. Under the action of the electric field and the coalescing packing, the tiny water droplets in the crude oil coalesce into larger water droplets. The device and method of this invention utilize magnetic fields to remove solid impurities and salts from crude oil, while simultaneously performing deep separation of oil and water in the crude oil through electric fields and coalescing fields. This not only improves processing efficiency and makes the process environmentally friendly, but also effectively extends the operating cycle of the device.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and in particular to a crude oil pretreatment device and method. Background Technology

[0002] In recent years, with the increasing trend of crude oil becoming inferior and heavier, heavy and inferior crude oil has high salt content, high viscosity, high density, and severe emulsification. Moreover, crude oil contains certain solid impurities, which bring many problems to the subsequent dehydration, desalting, oil-water separation and subsequent processing of crude oil. The main problems are: (1) Solid impurities in crude oil are prone to causing equipment and pipeline blockage and scaling during the post-processing process, and the system pressure increases; (2) Solid impurities are not easily polarized in traditional electro-desalting, which affects the electro-desalting effect; (3) When using traditional filtration and coalescence methods to process crude oil, it is easy to cause problems such as filter element blockage and coalescence packing blockage.

[0003] In existing technologies, crude oil pretreatment generally employs electrostatic desalting. This method first injects a small amount of water into the oil to wash and dissolve the salts, and then uses electrostatic desalting technology to separate the oil and water. However, with the increasing trend of crude oil deterioration and severe emulsification, electrostatic desalting technology has low demulsification efficiency, resulting in problems such as large amounts of demulsifier required, unsatisfactory oil-water separation effect, low efficiency of oil-water separation equipment, and severe entrainment of the two phases.

[0004] For the pretreatment of heavy and low-quality crude oil, the removal of solid impurities and the effective separation of oil and water are crucial. Currently, there is a lack of efficient pretreatment processes, complete sets of equipment, and methods for heavy and low-quality crude oil, which can solve problems such as filter element and coalescing packing blockage, excessive demulsifier dosage, unsatisfactory oil-water separation, and severe phase entrainment in existing traditional processes.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a crude oil pretreatment device and method that uses a magnetic field to remove solid impurities and salts from crude oil, while simultaneously using an electric field and a coalescence field to perform deep separation of oil and water in the crude oil, which not only improves processing efficiency but also effectively extends the operating cycle of the device.

[0007] To achieve the above objectives, according to a first aspect of the present invention, the present invention provides a crude oil pretreatment apparatus, comprising: a static mixing unit that receives crude oil after sedimentation separation and injects magnetic seeds and flocculants; a magnetic separation unit that has a cylindrical structure and is internally provided with multiple layers of magnetically coagulating media, wherein the multiple layers of magnetically coagulating media adsorb flocculated precipitates in the crude oil with magnetic seeds as the core through the action of a gradient magnetic field; and an oil-water deep separation unit that is provided with multiple layers of annularly spaced electrode plates and coalescing packing, wherein the oil-water deep separation unit receives crude oil after magnetic separation, and the crude oil flows sequentially through the multiple layers of coalescing packing, wherein under the action of an electric field and the coalescing packing, the tiny water droplets in the crude oil coalesce into larger water droplets.

[0008] Furthermore, in the above technical solution, a magnetic field generating device may be provided on the outside of the cylindrical structure, and the multilayer magnetic concentrating medium may be a stainless steel grid arranged at intervals.

[0009] Furthermore, in the above technical solution, the diameter of the stainless steel wires in the grille can be 0.45 to 0.55 mm; the spacing between the stainless steel wires is 1.5 to 2.5 mm; the spacing between adjacent grille layers can be 10 to 15 mm; the extension directions of the stainless steel wires in adjacent grille layers are staggered, and the staggering angle of the extension directions can be 0 to 90°.

[0010] Furthermore, in the above technical solution, the magnetic field generating device can be an electromagnetic induction coil wound around a cylindrical structure, generating a magnetic field strength of 4500 to 5500 G.

[0011] Furthermore, in the above technical solution, the multi-layered annularly spaced electrode plates may include: a first electrode plate disposed on the outermost layer; a second electrode plate disposed on the inner side of the first electrode plate, with a first cavity between the first electrode plate and the second electrode plate, the first cavity being filled with a first coalescing filler; a third electrode plate disposed on the inner side of the second electrode plate, with a second cavity between the second electrode plate and the third electrode plate, the second cavity being filled with a second coalescing filler; and the interior of the third electrode plate being a third cavity, the third cavity being filled with a third coalescing filler.

[0012] Furthermore, in the above technical solution, crude oil flows sequentially and back through the first coalescing packing, the second coalescing packing, and the third coalescing packing, with the packing precision of the first to the third coalescing packing increasing sequentially.

[0013] Furthermore, in the above technical solution, an alternating current can be applied between the first electrode plate, the second electrode plate, and the third electrode plate; the electric field strength in the first cavity is 400–500 V / cm; and the electric field strength in the second cavity is 900–1000 V / cm.

[0014] Furthermore, in the above technical solution, the first coalescing filler, the second coalescing filler, and the third coalescing filler can be woven from oleophilic and hydrophobic polypropylene fibers and hydrophilic and oleophobic polypropylene fibers in a 1:3 ratio.

[0015] Furthermore, in the above technical solution, the pretreatment device may also include: a mixer, which receives heated crude oil and injects water and demulsifier for mixing; and a settling tank, which receives the mixed crude oil for oil-water separation and introduces the separated crude oil into a static mixing unit.

[0016] Furthermore, in the above technical solution, the pretreatment device may also include: a sedimentation unit, which is located at the rear end of the oil-water deep separation unit, for sedimentation and separation of the dehydrated crude oil.

[0017] To achieve the above objectives, according to a second aspect of the present invention, the present invention provides a crude oil pretreatment method, comprising the following steps: A. Injecting magnetic seeds and flocculants into crude oil after sedimentation and separation; B. Using a gradient magnetic field, adsorbing the flocculent precipitates with magnetic seeds as the core in the crude oil using a multilayer magnetic media to remove solid particles from the crude oil; C. Using multilayer annularly spaced electrode plates and coalescing packing, coalescing the tiny water droplets in the crude oil into large water droplets to perform deep oil-water separation of the crude oil.

[0018] Furthermore, in the above technical solution, before step A, the following steps may be included: heating the crude oil and injecting water and demulsifier to mix them, and then allowing the mixed crude oil to stand and separate the oil and water.

[0019] Furthermore, in the above technical solution, the crude oil can be heated to 70-90°C before pretreatment; the amount of water added is 0.5-20 wt% of the crude oil mass; and the amount of demulsifier added is 0.001-0.05 wt% of the crude oil mass.

[0020] Furthermore, in the above technical solution, the settling time can be 10 to 120 minutes; the settling operation conditions are as follows: temperature is 40 to 120°C; pressure is atmospheric pressure to 2.0 MPa.

[0021] Furthermore, in the above technical solution, the magnetic seed can be metallic Fe, and the amount added can be 0.01 to 0.5 wt% of the crude oil mass; the flocculant can be one or a mixture of two or more of polyacrylamide, polyoxypropylene, polyvinyl alcohol, and polyethylene glycol, and the amount added can be 0.01 to 0.5 wt% of the crude oil mass.

[0022] Furthermore, in the above technical solution, the operating conditions for step B are as follows: temperature is 80-90℃, and pressure is atmospheric pressure to 0.5MPa.

[0023] Furthermore, in the above technical solution, the electric field strength formed in step C can be 300 to 1800 V / cm; the flow velocity of crude oil in the coalescing packing can be 0.001 to 0.1 m / s.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) According to the inventors' research, the mesh-type grid has a good separation effect. Since heavy, low-quality crude oil has high viscosity and is prone to clogging, a horizontally staggered grid is used for separation. The magnetic separation unit in this invention uses a layered grid built into the magnetic filter cylinder, with the stainless steel wires of each layer staggered at an angle, making it less prone to clogging when crude oil passes through. When the grid size, arrangement angle, and arrangement interval are within the preferred range of this invention, the interaction between the stainless steel wires is strong. This strong interaction bends the magnetic lines of force in the space as much as possible, resulting in a wider distribution of magnetic field strength on the plane. The multi-layered grids are staggered and magnetized in the magnetic field, and their surfaces can generate a gradient magnetic field (i.e., a non-uniform magnetic field along the radial direction of the magnetic filter cylinder), which can effectively separate solid impurities in the crude oil.

[0026] 2) In the crude oil dehydration process, the deep oil-water separation unit of this invention utilizes an electric field to drive the rapid migration of tiny water droplets. Through media interception and wetting / coalescing, it provides a wide range of media sites for droplet coalescence. The combined effect of the electric field and the coalescence field makes it easier for tiny water droplets to coalesce into larger droplets, which are then separated during subsequent settling, achieving deep dehydration of the crude oil. The crude oil dehydration process employs physical demulsification, offering advantages such as high efficiency, energy saving, and environmental friendliness.

[0027] 3) The device of the present invention couples magnetic fields, electric fields, coalescence fields, etc., and realizes the concentration and deep separation of oil and water through a set of devices, while effectively removing solid impurities from crude oil.

[0028] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0029] Figure 1 This is a schematic flowchart of the crude oil pretreatment method of the present invention.

[0030] Figure 2 This is a schematic diagram of the crude oil pretreatment device of the present invention.

[0031] Figure 3 This is a cross-sectional schematic diagram of the magnetic separation unit in the crude oil pretreatment device of the present invention.

[0032] Figure 4 This is a schematic diagram of the multi-layer stainless steel grid arrangement of the magnetic separation unit of the present invention.

[0033] Figure 5 This is a cross-sectional schematic diagram of an embodiment 1 of the oil-water deep separation unit in the crude oil pretreatment device of the present invention (showing the annular electrode plates of each layer and the coalescing packing between the electrode plates).

[0034] Figure 6 yes Figure 5 A schematic cross-sectional view of Comparative Example 1 of Example 1.

[0035] Figure 7 This is a schematic diagram of the longitudinal section of the oil-water deep separation unit of the present invention (showing the direction of crude oil flow).

[0036] Explanation of key figure labels:

[0037] 1-Crude oil inlet, 2-First distribution orifice plate, 3-DC power supply, 4-Magnetic separation unit, 41-Magnetic filter cylinder, 42-Electromagnetic induction coil, 43-Stainless steel grid, 5-Solid slag outlet, 6-First-stage baffle, 7-Second distribution orifice plate, 8-AC power supply, 9-Deep oil-water separation unit, 91-First coalescing packing, 92-Second coalescing packing, 93-Third coalescing packing, 94-First electrode plate, 95-Second electrode plate, 96-Third electrode plate, 10-Second-stage baffle, 11-Purified crude oil outlet, 12-Liquid level gauge, 13-Unit water tank, 14-Aqueous phase outlet. Detailed Implementation

[0038] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0039] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0040] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0041] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0042] The crude oil pretreatment device of this invention mainly includes a static mixing unit for injecting magnetic seeds and flocculants, a magnetic separation unit for separating solid particles in crude oil, and an oil-water deep separation unit for deep separation of crude oil. The device may also include a mixer for injecting water and demulsifiers, a settling tank, and a settling unit after deep oil-water separation. The connection sequence of each unit or device is described below. Figure 1 The above units or equipment will be described below according to the direction of crude oil flow.

[0043] Mixers and settling tanks:

[0044] like Figure 1 As shown, the mixer is used to receive heated crude oil and inject water and demulsifier for mixing. This mixer is a static mixer. The crude oil is heated to 70℃~90℃, and water and demulsifier are injected and thoroughly mixed in the mixer. The amount of water added can be 0.5~20wt% of the crude oil mass, and the demulsifier can be polyoxyethylene polyoxypropylene alcohol ether, with an addition amount of 0.001~0.05wt% of the crude oil mass. The settling tank is used to receive the mixed crude oil for oil-water separation and introduces the separated crude oil into the subsequent static mixing unit. The operating conditions can be: settling time of 10~120min, settling temperature of 40~120℃, and settling pressure of atmospheric pressure~2.0MPa.

[0045] Static mixing unit:

[0046] The static mixing unit receives crude oil after sedimentation and separation, and injects magnetic seeds and flocculants therein. Specifically, crude oil that has undergone preliminary dehydration and slag removal after sedimentation can be introduced into this static mixing unit and thoroughly mixed with flocculant polyacrylamide and magnetic seeds Fe. The flocculant can be one or a mixture of two or more of polyacrylamide, polyoxypropylene, polyvinyl alcohol, and polyethylene glycol, and the amount added can be 0.01 to 0.5 wt% of the crude oil mass. The amount of magnetic seeds added can also be 0.01 to 0.5 wt% of the crude oil mass. After mixing, the mixture is introduced into the magnetic separation unit of the multi-field synergistic enhanced crude oil pretreatment device of this invention.

[0047] Magnetic separation unit:

[0048] like Figures 2 to 4 As shown, the magnetic separation unit 4 of the present invention has a cylindrical structure and is internally equipped with multiple layers of magnetically concentrated media. This magnetic separation unit 4, through the action of a gradient magnetic field, utilizes the multiple layers of magnetically concentrated media to adsorb flocculated precipitates in crude oil with magnetic seeds as the core. Specifically, after static mixing, the crude oil enters the cylindrical structure (i.e., magnetic filter cylinder 41, preferably an aluminum cylinder) of the magnetic separation unit 4 through the first distribution perforated plate 2 from the crude oil inlet 1. The magnetic filter cylinder 41 is fixed on the first distribution perforated plate 2, and multiple cylinders can be arranged as needed, with the arrangement direction parallel to the flow direction of the crude oil. A magnetic field generating device can be provided outside the magnetic filter cylinder 41. The magnetic field generating device is an electromagnetic induction coil 42 wound around the magnetic filter cylinder 41 (which generates a magnetic field by being energized by a DC power supply 3). See [link to relevant documentation]. Figure 3 The generated magnetic field strength ranges from 0 to 6000 G, with a preferred range of 4500 to 5500 G used in this invention. The multilayer magnetic concentrating medium can be a spaced-apart stainless steel grid 43 (made of SUS430 stainless steel). The diameter of the stainless steel wires in the grid is preferably 0.45 to 0.55 mm. Further... Figure 4 As shown, the spacing d between the stainless steel wires is preferably 1.5 to 2.5 mm; the spacing L between adjacent grid layers is preferably 10 to 15 mm, and the extension directions of the stainless steel wires in adjacent grid layers are staggered (i.e., Figure 4 The extension directions of the magnetic filter cylinder 43a, 43b, 43c, and 43d are staggered at an angle of 0 to 90°, preferably 30°. The operating conditions of the magnetic filter cylinder 41 are as follows: temperature 80 to 90°C, pressure atmospheric pressure to 0.5 MPa.

[0049] A magnetic filter cylinder is used to separate magnetic flocs from crude oil. The inventors found that grid-type screens offer good separation performance. However, due to the high viscosity and tendency to clog heavy, low-quality crude oil, a horizontally staggered grid arrangement is employed. The grids are arranged regularly at a specific angle within the magnetic filter cylinder. When the grid size, angle, and spacing are within the preferred ranges, the interaction between the stainless steel wires is strong. This strong interaction bends the magnetic field lines in space, resulting in a wider distribution of the magnetic field strength across the plane. The multi-layered grids are staggered and magnetized in the magnetic field, generating a gradient magnetic field (i.e., a non-uniform magnetic field along the radial direction of the magnetic filter cylinder), effectively separating solid impurities from the crude oil. After a period of adsorption, the DC power supply is turned off, and the solid impurities fall off and are discharged from the solid residue outlet 5.

[0050] The magnetic separation unit of this invention incorporates horizontally staggered stainless steel grids. These grids are magnetized in a magnetic field, generating a gradient magnetic field on their surface. Solid particles in the crude oil mix evenly with the magnetic seeds and flocculant, forming flocculent precipitates with the magnetic seeds at their core. During flow, these precipitates are adsorbed onto the grids, achieving separation of solid impurities from the crude oil with higher efficiency. The magnetically separated crude oil overflows through a primary baffle 6 and flows from the top to the deep oil-water separation unit.

[0051] Oil-water deep separation unit:

[0052] like Figure 2 , 5 As shown in Figure 7, the crude oil after magnetic separation is received and subjected to deep oil-water separation. The deep oil-water separation unit 9 is fixed on the second orifice plate 7 and is equipped with multiple layers of annularly spaced electrode plates and coalescing packing. The crude oil flows sequentially through the multiple layers of coalescing packing. Under the combined action of the electric field and the coalescing packing, tiny water droplets in the crude oil can coalesce into larger water droplets. Specifically, the separation cylinder of the deep oil-water separation unit 9 of this invention can be configured as multiple cylinders arranged laterally, such as... Figure 2 As shown, the separation cylinder consists of three layers of annularly spaced electrode plates and coalescing filler. The electrode plates include a first electrode plate 94, a second electrode plate 95, and a third electrode plate 96. The first electrode plate 94 is annular and located on the outermost layer. The second electrode plate 95 is also annular and located inside the first electrode plate 94. A first cavity is provided between the first electrode plate 94 and the second electrode plate 95, and this first cavity is filled with first coalescing filler 91. The third electrode plate 96 is also annular and located inside the second electrode plate 95. A second cavity is provided between the second electrode plate 95 and the third electrode plate 96, and this second cavity is filled with second coalescing filler 92. The interior of the third electrode plate 96 is a third cavity, which is filled with third coalescing filler 93. An alternating current (AC) is applied between the electrode plates. Figure 2The AC power supply 8 is used in the system. Specifically, the first electrode plate 94 and the third electrode plate 96 are grounded, and the second electrode plate 95 is connected to the live wire. After power is applied, the electric field strength in the first cavity is 400-500 V / cm; the electric field strength in the second cavity is 900-1000 V / cm. The crude oil channels between the annular electrode plates (i.e., the three cavities) are filled with coalescing filler, with the filler precision increasing sequentially from the outer layer to the inner layer. The coalescing filler is woven from a mixture of oleophilic and hydrophobic polypropylene fibers and hydrophilic and oleophobic polypropylene fibers in a 1:3 ratio. Crude oil enters from the inlet, flows back through the three cavities sequentially, and is discharged from the outlet of the innermost channel (i.e., the third cavity).

[0053] The specific number of electrode plates and coalescing packing can be adjusted according to the water content and emulsification degree of the crude oil to be treated. Channels for crude oil flow are formed between the electrode plates, and these channels are filled with coalescing packing. The crude oil flows sequentially and back through each layer of channels, and under the influence of the electric field, the emulsified micro-droplets migrate rapidly within the electric field, accelerating the capture, coalescence, and growth of these micro-droplets in the coalescing fiber layer. The packing precision increases sequentially from the outer layer to the inner layer, allowing the unseparated micro-droplets in the outer layer (i.e., the first cavity) to undergo deep coalescence and separation in the subsequent packing (i.e., the packing in the second and third cavities), ultimately achieving deep dehydration of the crude oil. Preferably, but not limitingly, the flow velocity of the crude oil in the channels is 0.001–0.1 m / s.

[0054] The oil-water deep separation unit of this invention utilizes an electric field to drive the rapid migration of tiny water droplets. By leveraging the effects of media interception and wetting coalescing, it provides a wide range of media sites for droplet coalescence, solving the problem of low droplet collision interception efficiency in electric field coalescence. Through the combined action of the electric field and the coalescence field, tiny water droplets more easily coalesce into larger droplets, which are then separated during subsequent sedimentation. All of the above processes employ physical demulsification, offering advantages such as high efficiency, energy saving, and environmental friendliness.

[0055] Settlement unit:

[0056] A settling unit is located at the rear end of the deep oil-water separation unit 9, and is used to separate the crude oil after deep oil-water separation. The settling unit is equipped with vertically arranged secondary baffles 10. The purified crude oil after deep separation and dehydration flows out from the purified crude oil outlet 11 at the top of the settling unit, while the water after deep separation flows out from the aqueous phase outlet 14 at the water tank 13, achieving the settling separation of crude oil and water after deep separation. A level gauge 12 can be installed at the water tank 13 to monitor the liquid level of the aqueous phase.

[0057] The crude oil pretreatment method of the present invention uses the aforementioned apparatus and includes the following steps: heating the crude oil and injecting water and demulsifier for mixing, and then allowing the mixed crude oil to stand and separate oil and water; injecting magnetic seeds and flocculants into the crude oil after sedimentation and separation; using a gradient magnetic field, adsorbing the flocculent precipitates with magnetic seeds as the core in the crude oil using a multilayer magnetic medium to remove solid particles from the crude oil; and using multilayer annularly spaced electrode plates and coalescing packing to coalesce the tiny water droplets in the crude oil into large water droplets, thereby performing deep oil-water separation of the crude oil.

[0058] Example 1

[0059] The properties of the crude oil in Example 1 are shown in Table 1. It is characterized by high density, high viscosity, and severe emulsification.

[0060] Table 1 Crude Oil Properties Data

[0061]

[0062] Crude oil is heated to 75℃~85℃, and water and demulsifier polyoxyethylene polyoxypropylene alcohol ether are injected and thoroughly mixed in a mixer. The amount of water added is 10wt% of the crude oil mass; the amount of demulsifier added is 0.005~0.01wt% of the crude oil mass. The crude oil mixture is then introduced into a settling tank for oil-water separation. The settling time is 40min, the settling temperature is 80~90℃, and the settling pressure is atmospheric pressure~0.5MPa. The crude oil, after preliminary dehydration and slag removal, is introduced into a static mixing unit and thoroughly mixed with flocculant polyacrylamide and magnetic seed Fe. The amount of flocculant added is 0.05~0.1wt% of the crude oil mass, and the amount of magnetic seed added is 0.05~0.1wt% of the crude oil mass. After mixing, the mixture is introduced into a multi-field synergistic enhanced magnetic separation unit and a deep oil-water separation unit.

[0063] Crude oil flows through the first distribution orifice plate 2 and enters the magnetic separation unit 4. The magnetic separation unit consists of a magnetic filter cylinder 41 and an electromagnetic induction coil 42 wound around it, generating a magnetic field strength of 4500–5500 G. Inside the cylinder, four stainless steel grids 43 are arranged in a 30° staggered transverse direction. The diameter of the stainless steel wire is 0.5 mm; the wire spacing is 2 mm; and the spacing between the upper and lower layers of the grids is 10–15 mm. The operating conditions of the magnetic filter cylinder 41 are as follows: temperature 80–90℃, pressure atmospheric pressure to 0.5 MPa.

[0064] After magnetic separation, the crude oil passes through a primary baffle 6 and then through a second distribution orifice plate 7 to enter a deep oil-water separation unit enhanced by the synergistic effect of electric and coalescence fields. This unit consists of three separation cylinders fixed to the second distribution orifice plate 7. Each separation cylinder comprises three layers of inner and outer annularly spaced electrode plates and coalescing packing. Alternating current is applied between the electrode plates; the first electrode plate 94 and the third electrode plate 96 are grounded, and the second electrode plate 95 is connected to the power supply live wire. The electric field strength in the first chamber is 400–500 V / cm; the electric field strength in the second chamber is 900–1000 V / cm. The three chambers between the annular electrode plates are filled with coalescing packing, with the packing density increasing sequentially from the outermost layer to the innermost layer. The coalescing packing is woven from a 1:3 mixture of oleophilic and hydrophobic polypropylene fibers and hydrophilic and oleophobic polypropylene fibers. The crude oil enters through the inlet, flows through the three chambers sequentially, and exits through the outlet of the innermost channel.

[0065] Using the crude oil pretreatment method of Example 1, the treated crude oil had a solid content of 0.05–0.07 wt%, a salt content of 2.6–2.8 mg / L, and a water content of 0.27–0.30 wt%.

[0066] Comparative Example 1

[0067] Unlike Embodiment 1 of the present invention, only the third cavity (i.e., the innermost channel) in the oil-water deep separation unit's separation cylinder is filled with coalescing packing, see [link to previous embodiment]. Figure 6 That is, neither the first cavity nor the second cavity is filled with coalescing filler, and the two cavities only have the coalescing effect of the electric field alone.

[0068] Using the crude oil pretreatment method of Comparative Example 1, the treated crude oil had a solid content of 0.05–0.07 wt%, a salt content of 7.2–8.6 mg / L, and a water content of 0.98–1.30 wt%.

[0069] Data shows that when oil and water are separated by the combined use of electric field and coalescence field in Example 1 of this invention, the salt content and water content of the treated crude oil are significantly lower than those in Comparative Example 1, which only uses an electric field.

[0070] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A crude oil pretreatment device, characterized in that, include: The static mixing unit receives crude oil after sedimentation and separation and injects magnetic seeds and flocculants; The magnetic separation unit is a cylindrical structure with multiple layers of magnetic media inside. Under the action of a gradient magnetic field, the multiple layers of magnetic media adsorb the flocculent precipitates with magnetic seeds as the core in the crude oil, thus removing solid particles from the crude oil. The cylindrical structure is equipped with a magnetic field generating device on the outside. The multiple layers of magnetic media are stainless steel grids arranged at intervals. The stainless steel wires of adjacent grids extend in an interlaced direction. An oil-water deep separation unit is provided with multiple layers of annularly spaced electrode plates and coalescing packing. The oil-water deep separation unit receives the crude oil after magnetic separation. The crude oil flows through multiple layers of the coalescing packing in sequence. Under the action of the electric field and the coalescing packing, the tiny water droplets in the crude oil coalesce into larger water droplets. The multiple layers of annularly spaced electrode plates include: a first electrode plate, which is located on the outermost layer. A second electrode plate is disposed inside the first electrode plate, and a first cavity is provided between the first electrode plate and the second electrode plate, the first cavity being filled with a first coalescing filler; a third electrode plate is disposed inside the second electrode plate, and a second cavity is provided between the second electrode plate and the third electrode plate, the second cavity being filled with a second coalescing filler; the interior of the third electrode plate is a third cavity, the third cavity being filled with a third coalescing filler; crude oil flows sequentially and in reverse through the first coalescing filler, the second coalescing filler, and the third coalescing filler.

2. The crude oil pretreatment device according to claim 1, characterized in that, The diameter of the stainless steel wires in the grille is 0.45 to 0.55 mm; the spacing between the stainless steel wires is 1.5 to 2.5 mm; the spacing between adjacent grille layers is 10 to 15 mm; the intersecting angle of the extension directions of the stainless steel wires in adjacent grille layers is 0 to 90°, and the intersecting angle is not zero.

3. The crude oil pretreatment device according to claim 2, characterized in that, The magnetic field generating device is an electromagnetic induction coil wound around the cylindrical structure, which generates a magnetic field strength of 4500-5500G.

4. The crude oil pretreatment device according to claim 1, characterized in that, An alternating current is applied between the first electrode plate, the second electrode plate, and the third electrode plate; the electric field strength in the first cavity is 400–500 V / cm; and the electric field strength in the second cavity is 900–1000 V / cm.

5. The crude oil pretreatment apparatus according to claim 1, characterized in that, The first coalescing filler, the second coalescing filler and the third coalescing filler are woven from a mixture of oleophilic and hydrophobic polypropylene fibers and hydrophilic and oleophobic polypropylene fibers in a 1:3 ratio.

6. The crude oil pretreatment apparatus according to claim 1, characterized in that, The pretreatment device further includes: A mixer that receives heated crude oil and injects water and demulsifier for mixing; A settling tank receives the mixed crude oil, allows it to settle and separate oil and water, and then introduces the settled crude oil into the static mixing unit.

7. The crude oil pretreatment apparatus according to claim 1, characterized in that, The pretreatment device further includes: A settling unit, located at the rear end of the oil-water deep separation unit, is used to settling and separating the dehydrated crude oil.

8. A crude oil pretreatment method, characterized in that, Using the apparatus as described in any one of claims 1 to 7, the method includes the following steps: A. Inject the crude oil, after sedimentation and separation, into magnetic seed and flocculant; B. By using a gradient magnetic field, multilayer magnetic media adsorb the flocculent precipitate with magnetic seeds as the core in crude oil, thereby removing solid particles from the crude oil. C. Through multi-layered annularly spaced electrode plates and coalescing packing, tiny water droplets in crude oil are coalesced into larger water droplets, enabling deep oil-water separation of crude oil.

9. The crude oil pretreatment method according to claim 8, characterized in that, Before step A, the process further includes: heating the crude oil and injecting water and demulsifier to mix them, and then allowing the mixed crude oil to stand and separate the oil and water.

10. The crude oil pretreatment method according to claim 9, characterized in that, The crude oil is heated to 70-90°C before pretreatment; the amount of water added is 0.5-20 wt% of the crude oil mass; the amount of demulsifier added is 0.001-0.05 wt% of the crude oil mass.

11. The crude oil pretreatment method according to claim 8, characterized in that, The settling time is 10 to 120 minutes; the settling operation conditions are as follows: temperature is 40 to 120°C; pressure is atmospheric pressure to 2.0 MPa.

12. The crude oil pretreatment method according to claim 8, characterized in that, The magnetic seed is metallic Fe, and the amount added is 0.01 to 0.5 wt% of the crude oil mass; the flocculant is one or a mixture of two or more of polyacrylamide, polyvinyl alcohol, and polyethylene glycol, and the amount added is 0.01 to 0.5 wt% of the crude oil mass.

13. The crude oil pretreatment method according to claim 8, characterized in that, The operating conditions for step B are as follows: temperature is 80-90°C, and pressure is atmospheric pressure to 0.5MPa.

14. The crude oil pretreatment method according to claim 8, characterized in that, The electric field strength formed in step C is 300–1800 V / cm; the flow velocity of crude oil in the coalescing packing is 0.001–0.1 m / s.

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