A kind of oil purification device and method based on multi-stage gradient fiber dispersion-buoyancy extraction

Abstract

The application provides a kind of oil purification device and method based on multistage gradient fiber dispersion-buoyancy extraction.The application includes a plurality of fiber dispersion-buoyancy extraction units connected in series, the pore size of the porous fiber layer of the plurality of fiber dispersion-buoyancy extraction units gradually decreases, and in the extraction process, the oil passes through the porous fiber layer with gradually decreasing pore size in turn, and different size oil droplets are formed in each stage to enter the corresponding extraction tank for extraction, thereby realizing the gradual reduction of large particles, coarse micelles, gum, saponified substances and small and medium particles in waste oil, and the size of oil droplets is gradually reduced, which is beneficial to reduce the risk of rapid clogging of single-stage fine pore fiber and improve the extraction and separation effect; instead of stacking fibers with different pore sizes in the same module, the fiber dispersion-buoyancy extraction units are connected in series, so that each stage can independently realize the interception of pollutants, the generation of oil droplets and buoyancy extraction, thereby balancing the extraction efficiency, anti-clogging performance and oil-water separation stability.

Description

Technical Field

[0001] This invention relates to the field of oil and fat ion impurity removal technology, and in particular to an oil and fat purification device and method based on multi-level gradient fiber dispersion-flotation extraction. Background Technology

[0002] Waste oils include kitchen waste oil, frying waste oil, oil components from animal fat processing waste liquid, and other recycled oils. After appropriate pretreatment, these waste oils can be used as feedstock for biodiesel, green aviation fuel, hydrodeoxygenated fuels, or other bio-based fuels. However, waste oils typically contain metal ion impurities such as sodium, potassium, calcium, magnesium, iron, copper, zinc, and aluminum, as well as inorganic impurities such as phosphorus and chlorine. These impurities can lead to poisoning of subsequent hydrogenation catalysts, equipment corrosion, scaling, increased ash content, and decreased product quality; therefore, effective removal is necessary before they enter the deep conversion process.

[0003] Methods such as water washing, acid washing, complexation extraction, and ion exchange can be used to remove ionic impurities from waste oils. Among these, aqueous phase extraction has advantages such as low reagent cost, mild process, and ease of continuous operation. Existing filtration devices can usually only remove particulate or colloidal impurities and cannot simultaneously achieve oil phase fractionation and droplet formation and enhanced extraction mass transfer. Although existing single-stage micro-dispersion devices can generate smaller oil droplets, they are not adaptable to complex contaminants in waste oils and are prone to problems such as increased pressure drop, decreased flux, uneven droplet formation, and difficulty in cleaning after a period of operation. Some membrane dispersion or fiber dispersion devices can achieve immiscible phase dispersion, but most are single-stage structures and do not have a multi-stage gradient dispersion and extraction system for complex impurities in waste oils, resulting in poor extraction and separation effects. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of poor single-stage extraction and separation effect of existing waste oils and provide a waste oil purification device and method based on multi-stage gradient fiber dispersion-float extraction. This invention allows the oil to pass through fiber dispersion modules with different porosities or pore sizes in sequence, and forms oil droplets of different sizes at each stage that enter the corresponding extraction zone, thereby achieving graded retention, graded droplet formation and stepwise ion migration, which greatly improves the extraction and separation effect.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a waste oil purification device based on multi-stage gradient fiber dispersion-flotation extraction, comprising:

[0007] Multiple interconnected fiber dispersion-flotation extraction units, each comprising:

[0008] An extraction tank is provided inside, which is equipped with a porous fiber layer. The porous fiber layer and the extraction tank enclose an oil feeding area. An oil baffle is provided inside the extraction tank above the porous fiber layer. The oil baffle is provided with oil through holes. An oil outlet hole is opened on the side wall of the extraction tank above the oil baffle.

[0009] The extraction tank has an oil inlet port on its side wall below the porous fiber layer, which communicates with the oil inlet area.

[0010] The extraction tank has a first aqueous phase inlet and outlet port and a second aqueous phase inlet and outlet port respectively on the side wall between the porous fiber layer and the oil partition.

[0011] Among them, for any two adjacent fiber dispersion-float extraction units, the oil outlet of the previous fiber dispersion-float extraction unit is connected to the oil inlet of the next fiber dispersion-float extraction unit.

[0012] The pore size of the porous fiber layer of multiple interconnected fiber dispersion-flotation extraction units gradually decreases.

[0013] Secondly, the present invention also provides a method based on multi-level gradient fiber dispersion-float extraction, applied to the aforementioned oil purification device based on multi-level gradient fiber dispersion-float extraction, comprising the following steps:

[0014] The aqueous phase enters the extraction tank through the first aqueous phase inlet / outlet of the first fiber dispersion-flotation extraction unit;

[0015] The oil passes through the oil inlet of the first fiber dispersion-float extraction unit and enters the extraction tank through the porous fiber layer;

[0016] The aqueous phase and oil are extracted in an extraction tank to complete the first extraction. After separation, the oil after the first extraction is obtained.

[0017] After the first extraction, the oil passes through the oil inlet of the second fiber dispersion-float extraction unit, enters the extraction tank through the porous fiber layer, and is extracted in the extraction tank of the second fiber dispersion-float extraction unit. This completes the second extraction, separation, and yields the oil after the second extraction.

[0018] Repeat the above steps until the oil after the previous extraction is extracted using the last fiber dispersion-float extraction unit;

[0019] Among them, for any two adjacent fiber dispersion-float extraction units, the oil outlet of the previous fiber dispersion-float extraction unit is connected to the oil inlet of the next fiber dispersion-float extraction unit.

[0020] The pore size of the porous fiber layer of multiple interconnected fiber dispersion-flotation extraction units gradually decreases.

[0021] The waste oil purification device and method based on multi-level gradient fiber dispersion-flotation extraction of the present invention have the following advantages over the prior art:

[0022] 1. The waste oil purification device and method based on multi-stage gradient fiber dispersion-float extraction of the present invention includes multiple interconnected fiber dispersion-float extraction units, wherein the pore size of the porous fiber layers of the multiple fiber dispersion-float extraction units gradually decreases; during the extraction process, the oil passes through the porous fiber layers with progressively smaller pore sizes in sequence, and forms oil droplets of different sizes at each stage, which enter the corresponding extraction tank for extraction, thereby achieving the step-by-step reduction of large particles, coarse colloids, colloids, saponifications and small and medium-sized particles in the waste oil, while the oil droplet size decreases step by step, which helps to reduce the risk of rapid clogging of single-stage fine pore fibers and greatly improves the extraction and separation effect; by using interconnected fiber dispersion-float extraction units, instead of stacking fibers of different pore sizes in the same module, each stage can independently achieve pollutant interception, oil droplet generation and flotation extraction, thereby taking into account extraction efficiency, anti-clogging performance and oil-water separation stability;

[0023] 2. The waste oil purification device and method based on multi-level gradient fiber dispersion-float extraction of the present invention features a detachable porous fiber layer. During extraction, as the extraction process continues, the pores of the porous fiber layer are gradually blocked by oil. At this point, the porous fiber layer can be detached and regenerated or replaced. Regeneration can be performed through an electrochemical regeneration unit. When the electrochemical regeneration unit regenerates the porous fiber layer, the flowing electrolyte can flush the porous fiber layer to remove some of the oil. Simultaneously, during electrolysis, hydrogen bubbles are generated at the cathode. The disturbance of hydrogen bubbles, pore flushing, bubble peeling, bubble buoyancy entrainment, and changes in the local electrochemical environment promote the desorption and separation of oil within the porous fiber layer, thereby improving the flux recovery rate and service life of the porous fiber layer. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the waste oil purification device based on multi-level gradient fiber dispersion-float extraction according to the present invention.

[0026] Figure 2This is a schematic diagram of the structure of multiple interconnected fiber dispersion-float extraction units of the present invention;

[0027] Figure 3 This is a schematic diagram of the extraction vessel of the present invention;

[0028] Figure 4 This is a schematic diagram of the electrochemical regeneration unit for regenerating porous fiber layers according to the present invention;

[0029] Figure 5 The results of cumulative retention rate of particulate colloids, cumulative total metal removal rate, and total metal content of each stage of the fiber dispersion-float extraction unit in Example 1 of the present invention are as follows:

[0030] Figure 6 This is a comparison diagram of single-stage fiber dispersion and multi-stage fiber dispersion-flotation extraction in Example 2 of the present invention;

[0031] Figure 7 This diagram illustrates the impact of different regeneration methods on the performance recovery of the porous fiber layer in Example 4 of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0035] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms such as "above" is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use, or the orientation or positional relationship in which those skilled in the art are usually understood. It is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0036] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] This application provides a waste oil purification device based on multi-level gradient fiber dispersion-float extraction, such as... Figures 1-4 As shown, it includes:

[0039] Multiple interconnected fiber dispersion-flotation extraction units, each comprising:

[0040] An extraction tank 1 is provided inside a porous fiber layer 2. The porous fiber layer 2 and the extraction tank 1 enclose an oil feeding area 10. An oil partition 11 is provided inside the extraction tank 1 above the porous fiber layer 2. An oil through hole is provided on the oil partition 11. An oil discharge hole 15 is provided on the side wall of the extraction tank 1 above the oil partition 11.

[0041] The extraction tank 1 has an oil inlet hole 14 on its side wall below the porous fiber layer 2, which communicates with the oil inlet zone 10;

[0042] The extraction tank 1 has a first aqueous phase inlet / outlet hole 12 and a second aqueous phase inlet / outlet hole 13 respectively on the side wall between the porous fiber layer 2 and the oil partition 11.

[0043] Among them, for any two adjacent fiber dispersion-float extraction units, the oil outlet 15 of the previous fiber dispersion-float extraction unit is connected to the oil inlet 14 of the next fiber dispersion-float extraction unit.

[0044] The pore size of the porous fiber layer 2, consisting of multiple interconnected fiber dispersion-flotation extraction units, gradually decreases.

[0045] The waste oil purification device based on multi-stage gradient fiber dispersion-flotation extraction of the present invention includes multiple fiber dispersion-flotation extraction units connected in series. Specifically, the number of fiber dispersion-flotation extraction units is n (n is a positive integer, n≥2), for example, n is 2~8. Each fiber dispersion-flotation extraction unit includes: an extraction tank 1 and a porous fiber layer 2 located inside the extraction tank 1. The porous fiber layer 2 and the extraction tank 1 enclose an oil feeding area 10. An oil baffle 11 is provided above the porous fiber layer 2 inside the extraction tank 1. The oil baffle 11 has oil through holes. The side wall of the extraction tank 1 above the oil baffle 11 is... The extraction tank 1 has an oil discharge port 15; the side wall below the porous fiber layer 2 of the extraction tank 1 has an oil inlet port 14 that communicates with the oil inlet area 10; the side wall between the porous fiber layer 2 and the oil partition 11 of the extraction tank 1 has a first aqueous phase inlet port 12 and a second aqueous phase inlet port 13 respectively; wherein, for any two adjacent fiber dispersion-float extraction units, the oil discharge port 15 of the previous fiber dispersion-float extraction unit is connected to the oil inlet port 14 of the next fiber dispersion-float extraction unit; the pore size of the porous fiber layer 2 of the multiple interconnected fiber dispersion-float extraction units gradually decreases.

[0046] The working principle of the waste oil purification device based on multi-stage gradient fiber dispersion-flotation extraction of the present invention is as follows: The aqueous phase enters the extraction tank through the first aqueous phase inlet / outlet of the first fiber dispersion-flotation extraction unit; the oil enters the extraction tank through the oil inlet of the first fiber dispersion-flotation extraction unit and through a porous fiber layer; as the oil passes through the porous fiber layer, it forms oil droplets 20; the aqueous phase and oil droplets 20 are extracted in the extraction tank, thus completing the first extraction and separation, obtaining the oil after the first extraction; the oil after the first extraction enters the extraction tank through the oil inlet of the second fiber dispersion-flotation extraction unit and through a porous fiber layer, and is extracted in the extraction tank of the second fiber dispersion-flotation extraction unit, thus completing the second extraction and separation. The oil obtained after the second extraction is obtained; the above steps are repeated until the oil after the previous extraction is extracted using the last fiber dispersion-float extraction unit; the pore size of the porous fiber layers of multiple interconnected fiber dispersion-float extraction units gradually decreases; the porous fiber layer of the first fiber dispersion-float extraction unit has the largest pore size, which is used to retain charred particles, food residues and coarse colloids in the oil and form larger oil droplets; the porous fiber layers of the middle fiber dispersion-float extraction units have medium pore sizes, which are used to further retain gums, saponifications and small and medium-sized particles in the oil and form smaller oil droplets; the porous fiber layer of the last fiber dispersion-float extraction unit has the smallest pore size, which is used to form even smaller micro oil droplets and enhance the migration of ionic impurities to the extraction aqueous phase, thereby improving the extraction and separation effect. This invention relates to a waste oil purification device based on multi-stage gradient fiber dispersion-float extraction. Waste oil passes through a porous fiber layer with progressively smaller pore sizes, forming oil droplets of different sizes at each stage before entering the corresponding extraction tank for extraction. This process achieves the gradual reduction of large particles, coarse colloids, colloids, saponifications, and small to medium-sized particles in the waste oil. At the same time, the progressively smaller oil droplet size helps reduce the risk of rapid clogging of single-stage fine-pored fibers and greatly improves the extraction and separation effect.

[0047] In some embodiments, the number of fiber dispersion-flotation extraction units is three;

[0048] The average pore size of the porous fiber layer in the first fiber dispersion-flotation extraction unit is 300~1000 μm, and the average porosity is 80~95%. After passing through the porous fiber layer of the first fiber dispersion-flotation extraction unit, the oil droplets formed have a characteristic diameter of 1.0~3.0 mm.

[0049] The average pore size of the porous fiber layer in the second fiber dispersion-flotation extraction unit is 100~300 μm, and the average porosity is 70~90%. After passing through the porous fiber layer of the second fiber dispersion-flotation extraction unit, the oil droplets formed have a characteristic diameter of 0.5~1.5 mm.

[0050] The average pore size of the porous fiber layer in the third fiber dispersion-flotation extraction unit is 20~100 μm, and the average porosity is 50~85%; the characteristic diameter of the oil droplets formed after passing through the porous fiber layer of the third fiber dispersion-flotation extraction unit is 0.1~0.8 mm.

[0051] In some embodiments, each fiber dispersion-float extraction unit further includes:

[0052] Aqueous phase storage tank 3, the upper end of which is connected to the first aqueous phase inlet / outlet 12 via a pipe, and the lower end of which is connected to the second aqueous phase inlet / outlet 13 via a pipe;

[0053] Oil phase storage tank 4, which is connected to oil discharge port 15;

[0054] The upper end of the oil phase storage tank 4 of the previous fiber dispersion-flotation extraction unit is connected to the oil feed port 14 of the next fiber dispersion-flotation extraction unit.

[0055] In the above embodiments, each fiber dispersion-float extraction unit further includes: an aqueous phase storage tank 3 and an oil phase storage tank 4. The aqueous phase storage tank 3 stores an aqueous phase (as an extractant). The aqueous phase storage tank 3 is connected to a first aqueous phase inlet / outlet 12 and a second aqueous phase inlet / outlet 13. If the first aqueous phase inlet / outlet 12 is located above the second aqueous phase inlet / outlet 13, the aqueous phase enters through the first aqueous phase inlet / outlet 12 and exits through the second aqueous phase inlet / outlet 13, and the aqueous phase and oil are extracted countercurrently in the extraction tank. If the first aqueous phase inlet / outlet 12 is located below the second aqueous phase inlet / outlet 13, the aqueous phase enters through the first aqueous phase inlet / outlet 12 and exits through the second aqueous phase inlet / outlet 13, and the aqueous phase and oil are extracted cocurrently in the extraction tank. In this invention, the first aqueous phase inlet / outlet 12 is located... Above the second aqueous phase inlet / outlet 13, the aqueous phase and oil are extracted countercurrently in the extraction tank; the aqueous phase storage tank 3 is connected to the first aqueous phase inlet / outlet 12 and the second aqueous phase inlet / outlet 13 through a pipe, and a metering pump 30 is installed on the pipe to regulate the flow rate of the aqueous phase; in this invention, metering pumps are installed on other pipes to regulate the flow rate of the corresponding materials, and valves can also be installed; the extracted oil flows into the oil phase storage tank 4 through the oil outlet 15, and the upper end of the oil phase storage tank 4 of the previous fiber dispersion-float extraction unit is connected to the oil inlet 14 of the next fiber dispersion-float extraction unit, that is, the oil after the previous extraction enters the extraction tank again through the oil inlet 14 of the next fiber dispersion-float extraction unit for extraction.

[0056] In some embodiments, a first supporting porous plate 21 and a second supporting porous plate 22 are respectively provided above and below the porous fiber layer 2 in the extraction tank 1;

[0057] The porous fiber layer 2 is located between the first supporting porous plate 21 and the second supporting porous plate 22, and the side wall of the extraction tank 1 is hollowed out at the location corresponding to the porous fiber layer 2.

[0058] A sleeve 24 is fitted onto the corresponding hollow part of the extraction tank 1, and the sleeve 24 is detachably and fixedly connected to the side wall of the extraction tank.

[0059] The porous fiber layer 2 is covered with a sealing ring 23, and the porous fiber layer 2 can be removed from the hollow part;

[0060] Multiple holes are provided on both the first and second support porous plates. The hole diameter is 0.2~10 mm and the opening rate is 20~90%. The outer diameter of the first and second support porous plates matches the inner diameter of the extraction tank.

[0061] In the above embodiment, a first supporting porous plate 21 and a second supporting porous plate 22 are respectively provided above and below the porous fiber layer 2 inside the extraction tank 1. The porous fiber layer 2 is located between the first supporting porous plate 21 and the second supporting porous plate 22. The side wall of the extraction tank 1 is completely hollowed out at the location corresponding to the porous fiber layer 2. A sealing ring 23 is fitted around the outer periphery of the porous fiber layer 2. A sleeve 24 is fitted around the hollowed-out location of the extraction tank 1. The sleeve 24 completely covers the hollowed-out location, and its upper and lower ends extend vertically and cover the upper and lower parts of the side wall of the hollowed-out location. The diameter of the sleeve 24 is greater than [missing information]. The diameter of the extraction tank 1 is such that the sleeve 24 is detachably fixed to the side wall of the extraction tank 1, for example, the sleeve 24 is fixed to the side wall of the extraction tank 1 by screws; the sealing ring 23 on the outer periphery of the porous fiber layer 2 plays a sealing role to prevent grease and water phase from leaking out from the perforation; when the porous fiber layer 2 needs to be replaced or regenerated, first remove the sleeve 24 (for example, remove the screws), move the sleeve 24 up or down to expose the perforation, take out the porous fiber layer 2 along with the sealing ring 23, and then replace or regenerate the porous fiber layer 2.

[0062] In some embodiments, the last fiber dispersion-float extraction unit further includes a phase separation tank 41;

[0063] The phase separation tank 41 is equipped with a fiber coalescing packing 42, which is made of hydrophilic fibers through weaving.

[0064] Phase separation tank 41 is connected to the upper end of oil phase storage tank 4. The lower end of phase separation tank 41 is provided with water phase outlet and the upper end is provided with oil phase outlet.

[0065] In the above embodiment, the last fiber dispersion-float extraction unit also includes a phase separation tank 41, which is connected to the upper end of the corresponding oil phase storage tank 4. The phase separation tank 41 is provided with fiber coalescing packing 42, which is made of hydrophilic fibers through weaving.

[0066] Tiny water droplets entrained in the oil phase are trapped, aggregated, and discharged on the surface of the hydrophilic water-capturing fiber packing to obtain a purified oil phase product with low water content. Finally, the tiny water droplets entrained in the oil phase are discharged through the water phase outlet at the lower end of the phase separation tank 41 after agglomeration, while the finally purified oil phase is discharged through the oil phase outlet at the upper end of the phase separation tank 41 and the purified oil phase product is collected.

[0067] In some embodiments, supports are spaced apart within the phase separation tank, and fiber coalescing packing is installed between two supports. The fiber coalescing packing is a porous fiber coalescing packing formed by weaving, winding, stacking, or pressing hydrophilic fibers. It is used to intercept, capture, and coalesce entrained micro water droplets under continuous oil phase flow conditions, allowing the coalesced water droplets to be discharged through the aqueous phase outlet under gravity. The porosity of the fiber coalescing packing is 60%~98%, preferably 80%~95%; the pore size distribution is 1~500 μm, preferably 10~100 μm; the average fiber diameter of the hydrophilic fibers is 1~500 μm, preferably 5~100 μm. The hydrophilic water-capturing fibers include one or more of the following: cotton fibers, wood pulp fibers, viscose fibers, polyamide fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, hydrophilic modified polyester fibers, hydrophilic modified glass fibers, stainless steel fibers, ceramic fibers, or modified fibers with hydroxyl, carboxyl, amide, or sulfonic acid groups on their surface.

[0068] In some embodiments, the porous fiber layer is made of at least one of polypropylene fiber, polytetrafluoroethylene fiber, polyester fiber, glass fiber, stainless steel fiber felt, titanium fiber felt, carbon fiber felt, nickel foam, titanium foam, copper foam, and conductive carbon felt.

[0069] In some embodiments, if the porous fiber layer is made of a conductive material, the grease purification device further includes an electrochemical regeneration unit for electrochemically regenerating the porous fiber layer. The electrochemical regeneration unit includes:

[0070] Electrolytic cell 6 is provided with a diaphragm 61, an anode 62 and a cathode 2, wherein the cathode is a porous fiber layer;

[0071] Power supply 63, which is used to connect anode 62 and cathode 2;

[0072] An electrolyte storage tank 64 is connected to an electrolytic cell 6 and is used to introduce electrolyte into the electrolytic cell 6;

[0073] Hydrogen collection tank 65 is connected to electrolyzer 6 and is used to collect hydrogen generated during the regeneration process;

[0074] Oil trap 66 is connected to electrolytic cell 6 and is used to collect oil generated during the regeneration process.

[0075] Specifically, the electrochemical regeneration unit includes an electrolytic cell 6, an electrolyte storage tank 64, a hydrogen collection tank 65, and an oil trap storage tank 66. The electrolytic cell 6 is a hollow rectangular chamber structure. Inside the electrolytic cell 6 are a diaphragm 61, an anode 62, and a cathode 2. A power supply 63 passes through the upper wall of the electrolytic cell with wires and is connected to the anode 62 (connected to the positive terminal of the power supply) and the cathode 2 (connected to the negative terminal of the power supply). The cathode 2 is a porous fiber layer. The diaphragm 61 is specifically an ion exchange membrane. The lower end of the electrolytic cell 6 has an electrolyte inlet 69 and an electrolyte outlet 60. The electrolyte storage tank 64 is connected to the electrolyte inlet 69 and the electrolyte outlet 60 via pipes. A hydrogen collection tank is located on the electrolytic cell 6. Hydrogen outlet 67 is connected to hydrogen collection tank 65; an oil outlet 68 is provided on electrolytic cell 6, and an oil trap storage tank 66 is connected to oil outlet 68; during extraction, as the extraction process continues, the pores of the porous fiber layer are gradually blocked by oil, at which point the porous fiber layer needs to be regenerated or replaced. Regeneration can be carried out through the above-mentioned electrochemical regeneration unit. Specifically, power supply 63 is connected to anode 62 and cathode 2 for electrolysis, and the electrolyte in electrolyte storage tank 64 flows into electrolytic cell 6 through electrolyte inlet 69; when rinsing and regeneration are required, the electrolyte can flow back into electrolyte storage tank 64 through electrolyte outlet 60, thereby forming a circulating flow (e.g. Figure 4 As shown by the middle arrow 71, the electrolyte flow can flush the porous fiber layer to remove some of the oil sludge 70. At the same time, during electrolysis, hydrogen bubbles 72 are generated at the cathode. The disturbance of the hydrogen bubbles 72, the flushing of the pores, the peeling of the bubbles, the buoyancy of the bubbles and the changes in the local electrochemical environment promote the desorption and separation of oil sludge in the porous fiber layer, thereby improving the flux recovery rate and service life of the porous fiber layer.

[0076] In one specific embodiment, the ion exchange membrane is a cation exchange membrane, including but not limited to Nafion NR211, Nafion N117, or Nafion NR212; in other embodiments, the ion exchange membrane may also be an anion exchange membrane, a cation exchange membrane, or a bipolar membrane, such as Fumatech FAA-3-PK-130 anion exchange membrane, Nafion series cation exchange membranes, or Fumatech FBM-PK bipolar membrane.

[0077] In some embodiments, the first fiber dispersion-float extraction unit further includes: an oil phase raw material tank 5 for storing oil; the oil phase raw material tank 5 is connected to an oil feed port 14; the oil phase raw material tank 5 stores oil to be processed, and the oil to be processed enters the oil feed area 10 through a pipe and the oil feed port 14, and a metering pump is provided on the pipe to regulate the flow rate of the oil.

[0078] Based on the same inventive concept, this invention also provides a method for purifying oils based on multi-level gradient fiber dispersion-float extraction, applied to the aforementioned oil purification device based on multi-level gradient fiber dispersion-float extraction, comprising the following steps:

[0079] S1. The aqueous phase enters the extraction tank through the first aqueous phase inlet / outlet of the first fiber dispersion-float extraction unit;

[0080] S2. The oil passes through the oil inlet of the first fiber dispersion-float extraction unit and enters the extraction tank through the porous fiber layer;

[0081] S3. The aqueous phase and oil are extracted in the extraction tank to complete the first extraction. After separation, the oil after the first extraction is obtained.

[0082] S4. The oil after the first extraction passes through the oil inlet of the second fiber dispersion-float extraction unit, enters the extraction tank through the porous fiber layer, and is extracted in the extraction tank of the second fiber dispersion-float extraction unit. This completes the second extraction and separation, and the oil after the second extraction is obtained.

[0083] Repeat the above steps until the oil after the previous extraction is extracted using the last fiber dispersion-float extraction unit;

[0084] Among them, for any two adjacent fiber dispersion-float extraction units, the oil outlet of the previous fiber dispersion-float extraction unit is connected to the oil inlet of the next fiber dispersion-float extraction unit.

[0085] The pore size of the porous fiber layer of multiple interconnected fiber dispersion-flotation extraction units gradually decreases.

[0086] Specifically, in the multi-level gradient fiber dispersion-flotation extraction method of the present invention, the aqueous phase enters the extraction tank through the first aqueous phase inlet / outlet of the fiber dispersion-flotation extraction unit; the oil enters the oil feed zone through the oil feed inlet, and then enters the extraction tank through the porous fiber layer; when the oil passes through the porous fiber layer, it forms oil droplets; the aqueous phase and oil droplets are extracted in the extraction tank; the above steps are repeated until the last fiber dispersion-flotation extraction unit is used to extract the oil after the previous extraction; finally, the extracted oil enters the phase separation tank, where water is removed under the action of the fiber coalescing packing to obtain a low-water-content purified oil phase product.

[0087] In some embodiments, the aqueous phase includes water, an acidic aqueous solution, or an aqueous solution containing a complexing agent;

[0088] The acid in the acidic aqueous solution is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, citric acid, oxalic acid, and lactic acid. The concentration of the acid in the acidic aqueous solution is 0.001~2 mol / L, preferably 0.005~0.5 mol / L.

[0089] The complexing agent in the aqueous solution is selected from one or more of citrate, acetate, EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), NTA (nitrotriacetic acid), aminocarboxylic acid compounds or their salts, and the concentration of the complexing agent in the aqueous solution is 0.0001~1 mol / L, preferably 0.001~0.2 mol / L;

[0090] The extraction temperature is 20~95℃;

[0091] The flow rate of the oil entering the extraction tank through the oil inlet through the porous fiber layer is 1~500 mL / min;

[0092] The flow rate of the aqueous phase entering the extraction tank through the first aqueous phase inlet / outlet is 1~5000 mL / min.

[0093] The oil to be processed in this invention is waste oil, specifically kitchen waste oil, swill oil, waste animal and vegetable oil, frying waste oil, acidified oil, oil refining byproducts, palm oil processing waste oil, or a mixture thereof; the ionic impurities in the oil include Na. + K + Ca 2+ Mg 2+ Fe 2+ Fe 3+ Cu 2+ Zn 2+ Al 3+ Mn 2+ Ni 2+ Cr 3+ One or more metal ions, as well as chlorine-, phosphorus-, sulfur-containing ionic compounds, salts, metal soaps, ash precursors, or combinations thereof.

[0094] In some embodiments, the process further includes regenerating the porous fiber layer, specifically:

[0095] The porous fiber layer to be regenerated is removed, and then used as a cathode. The porous fiber layer is regenerated using an electrochemical regeneration unit. The specific steps include:

[0096] Remove the porous fiber layer to be regenerated and place it in the electrolytic cell of the electrochemical regeneration unit. When the porous fiber layer is a conductive material, use it as the cathode and connect it to the negative terminal of the power supply, and connect the anode to the positive terminal of the power supply. Introduce electrolyte into the electrolytic cell at a voltage of 1–30 V and a current density of 1–200 mA / cm². 2 Electrolysis for 1~60 min desorbs oil stains from the surface and pores of the porous fiber layer, which are then discharged with the flow of electrolyte and the rising of hydrogen bubbles.

[0097] The electrolyte includes at least one of sodium sulfate solution, sodium chloride solution, sodium carbonate solution, sodium hydroxide solution, sulfuric acid solution, hydrochloric acid solution, and citric acid solution;

[0098] The electrolyte concentration is 0.001~1 mol / L;

[0099] During regeneration, the electrolyte in the electrolyte storage tank flows into the electrolytic cell through the electrolyte inlet, and the electrolyte can flow back into the electrolyte storage tank through the electrolyte outlet; when flushing and regeneration are required, the electrolyte can be circulated.

[0100] The present invention relates to a multi-stage gradient fiber dispersion-flotation extraction method. In this method, the pore size of the porous fiber layers in the interconnected fiber dispersion-flotation extraction units gradually decreases. During extraction, the oil sequentially passes through the progressively smaller pore size of the porous fiber layers, forming oil droplets of different sizes at each stage before entering the corresponding extraction tank for extraction. This achieves the step-by-step reduction of large particles, coarse micelles, colloids, saponifications, and small to medium-sized particles in waste oil. Simultaneously, the progressively smaller oil droplet size helps reduce the risk of rapid clogging of single-stage fine-pore fibers and significantly improves the extraction and separation effect. The use of interconnected fiber dispersion-flotation extraction units...

[0101] Instead of simply stacking fibers of different pore sizes in the same module, this invention enables each stage to independently achieve contaminant retention, oil droplet generation, and flotation extraction. The oil completes one oil-water contact and ion migration in each stage of flotation extraction before entering the next stage for further refinement and deep extraction, thus taking into account mass transfer efficiency, emulsification risk, and oil-water separation stability.

[0102] The present invention relates to a multi-level gradient fiber dispersion-float extraction method. The porous fiber layer is detachable. During extraction, as the extraction process continues, the pores of the porous fiber layer are gradually blocked by oil. At this point, the porous fiber layer can be detached and regenerated or replaced. Regeneration can be performed through an electrochemical regeneration unit. When the electrochemical regeneration unit regenerates the porous fiber layer, the flowing electrolyte can flush the porous fiber layer to remove some of the oil. At the same time, during electrolysis, hydrogen bubbles are generated at the cathode. The hydrogen bubble disturbance, pore flushing, bubble peeling, bubble buoyancy entrainment, and local electrochemical environment changes promote the desorption and separation of oil in the porous fiber layer, thereby improving the flux recovery rate and service life of the porous fiber layer.

[0103] The waste oil purification device based on multi-level gradient fiber dispersion-float extraction of the present invention is further illustrated below with specific embodiments. This section further illustrates the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0104] In the following examples, unless otherwise specified, the extraction temperature was 45 °C; during extraction, the aqueous phase was a mixed aqueous solution of 0.03 mol / L citric acid and 0.02 mol / L sodium chloride, and the pH was adjusted to 3.0 with hydrochloric acid; the oil flow rate was 60 mL / min, the flow rate of each stage of the aqueous phase was 180 mL / min, and the volumetric flow rate ratio of the extraction aqueous phase to the oil was 3:1. The first-stage porous fiber layer had an average pore size of 600 μm, a porosity of 90%, and a thickness of 5 mm; the second-stage porous fiber layer had an average pore size of 200 μm, a porosity of 82%, and a thickness of 3 mm; the third-stage porous fiber layer had an average pore size of 80 μm, a porosity of 70%, and a thickness of 2 mm. Both the first and second supporting porous plates were made of stainless steel porous plates with a thickness of 1.0 mm, an opening diameter of 1.0 mm, and an opening rate of 45%. The fiber coalescing packing is woven from polyamide fibers with an average pore size of 40 μm and an average porosity of 85%. The membrane in the electrochemical regeneration unit is an ion exchange membrane, specifically a Nafion NR211 cation exchange membrane.

[0105] Example 1

[0106] This embodiment provides a method based on multi-level gradient fiber dispersion-flotation extraction. Using waste cooking oil as the treatment target, ICP-OES analysis revealed the following main metal ion contents: Na 14.0 mg / kg, K 7.5 mg / kg, Ca 23.0 mg / kg, Mg 5.8 mg / kg, Fe 1.7 mg / kg, and total metals 52.0 mg / kg. The method employs... Figure 1 The apparatus (comprising three interconnected fiber dispersion-float extraction units) processes the aforementioned oils, including the following steps:

[0107] S1. The aqueous phase enters the extraction tank through the first aqueous phase inlet / outlet of the first fiber dispersion-float extraction unit;

[0108] S2. The oil passes through the oil inlet of the first fiber dispersion-float extraction unit and enters the extraction tank through the porous fiber layer;

[0109] S3. The aqueous phase and oil are extracted in the extraction tank to complete the first countercurrent extraction, and then separated to obtain the oil after the first extraction.

[0110] S4. The oil after the first extraction passes through the oil inlet of the second fiber dispersion-float extraction unit, enters the extraction tank through the porous fiber layer, and is extracted in the extraction tank of the second fiber dispersion-float extraction unit. This completes the second countercurrent extraction and separation, and the oil after the second extraction is obtained.

[0111] S5. The oil after the second extraction passes through the oil inlet of the third fiber dispersion-float extraction unit, enters the extraction tank through the porous fiber layer, and is extracted in the extraction tank of the third fiber dispersion-float extraction unit. This completes the third countercurrent extraction, separation, and the oil after the third extraction.

[0112] S6. The oil after the third extraction enters the phase separation tank, where water is removed by the fiber coalescing packing to obtain a purified oil phase product with low water content.

[0113] The porous fiber layer of the first fiber dispersion-flotation extraction unit is made of polypropylene fiber felt with an average pore size of 600 μm, a porosity of 90%, and a thickness of 5 mm. When the oil passes through the porous fiber layer of the first fiber dispersion-flotation extraction unit, the oil droplets formed have a characteristic diameter of 1.7 mm.

[0114] The porous fiber layer of the second fiber dispersion-flotation extraction unit is made of stainless steel fiber with an average pore size of 200 μm, a porosity of 82%, and a thickness of 3 mm. The oil after the first extraction passes through the porous fiber layer of the second fiber dispersion-flotation extraction unit again, and the oil droplets formed have a characteristic diameter of 0.9 mm.

[0115] The porous fiber layer of the third fiber dispersion-flotation extraction unit is made of nickel foam conductive fiber layer with an average pore size of 80 μm, a porosity of 70%, and a thickness of 2 mm. The oil after the second extraction passes through the porous fiber layer of the third fiber dispersion-flotation extraction unit again, and the oil droplets formed have a characteristic diameter of 0.4 mm.

[0116] For each extraction, the aqueous phase used was a mixed aqueous solution of 0.03 mol / L citric acid and 0.02 mol / L sodium chloride, and the pH was adjusted to 3.0 with hydrochloric acid.

[0117] The extraction temperature was 45 ℃ for each extraction, and the flow rate of the oil through the oil inlet was 60 mL / min for each extraction. The flow rate of the aqueous phase entering the extraction tank through the first aqueous phase inlet / outlet was 180 mL / min for each extraction.

[0118] Following the method in Example 1, the cumulative retention rate of particulate matter, cumulative total metal removal rate, and total metal content of the oil were further investigated after passing through the first fiber dispersion-float extraction unit (i.e., after primary extraction), the second fiber dispersion-float extraction unit (i.e., after secondary extraction), and the third fiber dispersion-float extraction unit (i.e., after tertiary extraction). The results are as follows: Figure 5 As shown in Table 1.

[0119] Table 1 - Cumulative Retention Rate of Particulate Matter and Cumulative Total Metal Removal Rate at Each Extraction Stage

[0120]

[0121] Depend on Figure 5As shown in Table 1, when the oil passes through the porous fiber layer of the first fiber dispersion-flotation extraction unit, it mainly retains coarse particles and micelles, while simultaneously achieving initial ion migration by forming larger oil droplets. After the first extraction, the oil passes through the porous fiber layer of the second fiber dispersion-flotation extraction unit, further retaining colloids and saponifies, reducing the oil droplet size to 0.86 mm and the total metal content to 17.8 mg / kg. After the second extraction, the oil passes through the porous fiber layer of the third fiber dispersion-flotation extraction unit, forming 0.42 mm micro-droplets and achieving deep extraction, further reducing the total metal content to 8.9 mg / kg. These results indicate that multi-stage fiber dispersion-flotation extraction achieves high ion removal efficiency by progressively reducing oil droplet size and contaminants.

[0122] Furthermore, following the method in Example 1, the removal effect of three-stage fiber dispersion-flotation extraction on different ionic impurities was investigated, and the results are shown in Table 2 below.

[0123] Table 2 - Removal effect of three-stage fiber dispersion-flotation extraction on different ionic impurities

[0124]

[0125] As shown in Table 2, the three-stage fiber dispersion-flotation extraction exhibits high removal rates for polyvalent metal ions such as Ca, Mg, and Fe, and also demonstrates significant removal effects for monovalent metal ions such as Na and K. The total metal content decreased from 52.0 mg / kg to 8.9 mg / kg, with a total metal removal rate of 82.9%. This indicates that multi-stage fiber dispersion-flotation extraction, by progressively forming smaller oil droplets and prolonging the oil-water contact process, can significantly promote the migration of ionic impurities into the aqueous phase.

[0126] Following the method in Example 1, after three-stage extraction, the total metal ion content in the purified oil phase decreased from the initial 52.0 mg / kg to 8.9 mg / kg, with a total metal removal rate of 82.9%. After extraction by the third fiber dispersion-float extraction unit, the turbidity of the oil-water mixture before phase separation flowing out of the oil outlet was 310 NTU, and the thickness of the emulsion layer after standing and phase separation was 3.5 mm.

[0127] Example 2

[0128] This embodiment provides a comparison between single-stage fiber dispersion and three-stage fiber dispersion-flotation extraction.

[0129] This embodiment compares the effects of single-stage fine fiber dispersion, single-stage coarse fiber dispersion, and three-stage fiber dispersion-flotation extraction on droplet formation, pressure drop, ion removal, and continuous operation stability; wherein, single-stage fine fiber dispersion and single-stage coarse fiber dispersion are employed... Figure 1The apparatus shown differs in that it contains only one fiber dispersion-float extraction unit; the porous fiber layer used in the single-stage coarse fiber extraction is made of polypropylene fiber felt with an average pore size of 600 μm, a porosity of 90%, and a thickness of 5 mm; the porous fiber layer used in the single-stage fine fiber extraction is made of nickel foam conductive fiber layer with an average pore size of 80 μm, a porosity of 70%, and a thickness of 2 mm; the three-stage fiber dispersion-float extraction is performed according to the method in Example 1; the extraction temperature, aqueous phase composition, oil flow rate, and aqueous phase flow rate are the same as in Example 1 for single-stage fine fiber dispersion, single-stage coarse fiber dispersion, and three-stage fiber dispersion-float extraction, and the extraction results are shown in Table 3 below. Figure 6 As shown.

[0130] It should be noted that in the single-stage coarse fiber and single-stage fine fiber experiments, the raw waste oil directly enters the single-fiber dispersion-flotation extraction unit; in the three-stage fiber dispersion-flotation extraction experiment, the oil passes through the first, second, and third-stage fiber dispersion-flotation extraction units sequentially, with each subsequent stage processing the oil phase collected after the previous stage's extraction. Therefore, the basic operating conditions are the same for all groups of experiments, but the feed contamination load and pressure drop accumulation methods experienced by each fiber layer differ.

[0131] Table 3 - Results of Single-Stage Fiber Dispersion and Tertiary-Stage Fiber Dispersion-Flotation Extraction

[0132]

[0133] In Table 3, the initial pressure drop refers to the pressure difference before and after the oil passes through the corresponding porous fiber layer during the initial extraction. The pressure drop after 6 hours of operation refers to the pressure difference before and after the oil passes through the corresponding porous fiber layer after 6 hours of extraction. For example, 4.0 / 7.5 / 12.0 in Table 3 means that the pressure drops of the oil passing through the first, second, and third porous fiber layers are 4.0 kPa, 7.5 kPa, and 12.0 kPa, respectively. The continuous stable operating time refers to the normal operating time of the extraction process.

[0134] From Table 3 and Figure 6 It is evident that single-stage coarse fiber exhibits good anti-clogging performance, but produces larger oil droplets, resulting in a total metal removal rate of only 52.0%. Single-stage fine fiber can form 0.45 mm oil droplets, increasing the total metal removal rate to 76.5%, but it suffers from a high initial pressure drop, rising to 48.0 kPa after 6 hours of operation, with the effluent turbidity reaching 560 NTU, indicating a higher risk of clogging and emulsification. Three-stage fiber dispersion-flotation extraction, through step-by-step droplet formation and extraction, achieves a total metal removal rate of 82.9%, with pressure drop shared across stages, and a continuous stable operating time of 12.0 h, demonstrating that multi-stage independent fiber dispersion-flotation extraction is superior to single-stage fiber dispersion.

[0135] Example 3

[0136] The extraction was performed according to the method in Example 1 (the difference from Example 1 is that each porous fiber layer used a foamed nickel conductive fiber layer with corresponding average pore size and porosity, while the other conditions were the same as in Example 1), for 0-12 h, 12-24 h, and 24-36 h respectively. During the extraction process, each fiber dispersion-float extraction unit had two porous fiber layers, denoted as A and B, with one working and the other regenerated for backup. During regeneration, the contaminated porous fiber layer was removed and placed in an electrolytic cell, using a 0.05 mol / L Na2SO4 aqueous solution as the electrolyte, the porous fiber layer as the cathode, and a stainless steel plate as the anode, under constant current mode at 20 mA / cm². 2 Electrolysis was performed at a current density of 3.0–5.0 V, with regeneration lasting 8 min. During regeneration, the electrolyte was circulated at a flow rate of 100 mL / min. The average total metal removal rate was measured at 0–12 h, 12–24 h, and 24–36 h, and the results are shown in Table 4 below.

[0137] Table 4 - Average Total Metal Removal Rate during 0~12h, 12~24h, and 24~36h of Operation

[0138]

[0139] The above results show that by alternating the operation of two porous fiber layers, the fiber dispersion-flotation extraction units at each level can complete the replacement and regeneration of the contaminated module without changing the main feed path of the oil phase. During 36 hours of continuous operation, the average oil phase flow rate was maintained at 59.2 mL / min to 60.5 mL / min, and the total metal removal rate was maintained at 81.8% to 82.9%, indicating that the device has the capability for continuous operation.

[0140] Example 4

[0141] This embodiment investigated the performance recovery effect of a contaminated porous fiber layer after detachment from the fiber dispersion-flotation extraction unit and different regeneration methods in an independent regeneration unit. After running for 12 hours according to the method in Example 1, the pressure drop of the third porous fiber layer (specifically, the nickel foam conductive fiber layer) increased from the initial 12.0 kPa to 35.0 kPa, and the oil phase flux decreased to 52% of the initial flux. Subsequently, water backwashing, acidic water backwashing, electrically assisted gas generation regeneration, and a combination of electrically assisted gas generation and electrolyte washing were employed for regeneration. Specifically, water backwashing involved placing the contaminated porous fiber layer in the regeneration tank and backwashing with deionized water from the oil outlet side to the oil inlet side for 10 minutes at a flow rate of 100 mL / min; acidic water backwashing involved backwashing with a pH 3.0 hydrochloric acid aqueous solution for 10 minutes at a flow rate of 100 mL / min; and electrically assisted gas generation regeneration involved using 0.05 mol / L... Na₂SO₄ was used as the electrolyte, a porous fiber layer served as the cathode, and a stainless steel plate served as the anode. The current was applied in constant current mode at 20 mA / cm². 2 Electrolysis was performed at a current density of 3.0–5.0 V, with the cell voltage maintained at 3.0–5.0 V for 8 min, during which the electrolyte remained stationary. Combined regeneration with electrically assisted gas generation and electrolyte rinsing involved circulating the electrolyte at a rate of 100 mL / min under the aforementioned electrically assisted gas generation regeneration conditions. Hydrogen microbubbles were generated within the pores of the nickel foam fibers. These microbubbles nucleated, grew, and desorbed within the fiber pores, promoting the removal of contaminants from the fiber surface and pores. Simultaneously, as the hydrogen microbubbles rose, they carried desorbed oil, colloids, and saponified contaminants to the surface of the regeneration liquid, thereby enhancing the separation of contaminants from the conductive nickel foam fiber layer. The results of different regeneration methods are shown in Table 5 below.

[0142] Table 5 - Results of different regeneration methods

[0143]

[0144] Table 5 shows that simple water backwashing has limited effectiveness in removing colloidal and saponified contaminants from the fiber channels, with a flux recovery rate of only 62.0%. Electric-assisted gas generation regeneration can increase the flux recovery rate to 91.0% and the pressure drop recovery rate to 86.0%. When electric-assisted gas generation is used in conjunction with electrolyte flushing, the flux recovery rate reaches 96.0%, the pressure drop recovery rate reaches 92.0%, and the continuous operating time after regeneration recovers to 12.0 h. This indicates that electric-assisted gas generation in conductive fiber modules can promote contaminant desorption and separation through microbubble agitation, peeling, and buoyancy entrainment, thereby improving the regeneration efficiency of the fiber modules.

[0145] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0146] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. An oil purification device based on multi-stage gradient fiber dispersion-float extraction, characterized in that, include: Multiple interconnected fiber dispersion-flotation extraction units, each comprising: An extraction tank is provided inside, which is equipped with a porous fiber layer. The porous fiber layer and the extraction tank enclose an oil feeding area. An oil baffle is provided inside the extraction tank above the porous fiber layer. The oil baffle is provided with oil through holes. An oil outlet hole is opened on the side wall of the extraction tank above the oil baffle. The extraction tank has an oil inlet port on its side wall below the porous fiber layer, which communicates with the oil inlet area. The extraction tank has a first aqueous phase inlet and outlet port and a second aqueous phase inlet and outlet port respectively on the side wall between the porous fiber layer and the oil partition. Among them, for any two adjacent fiber dispersion-float extraction units, the oil outlet of the previous fiber dispersion-float extraction unit is connected to the oil inlet of the next fiber dispersion-float extraction unit. The pore size of the porous fiber layer of multiple interconnected fiber dispersion-flotation extraction units gradually decreases.

2. The grease purification device as described in claim 1, characterized in that, The number of fiber dispersion-flotation extraction units is 3; The porous fiber layer of the first fiber dispersion-flotation extraction unit has an average pore size of 300–1000 μm and an average porosity of 80–95%. The porous fiber layer of the second fiber dispersion-flotation extraction unit has an average pore size of 100–300 μm and an average porosity of 70–90%. The average pore size of the porous fiber layer in the third fiber dispersion-flotation extraction unit is 20~100 μm, and the average porosity is 50~85%.

3. The grease purification device as described in claim 1, characterized in that, Each of the fiber dispersion-flotation extraction units also includes: A water phase storage tank, which is connected to the first water phase inlet and outlet port and the second water phase inlet and outlet port respectively; An oil phase storage tank, which is connected to the oil discharge port; The upper end of the oil phase storage tank of the previous fiber dispersion-flotation extraction unit is connected to the oil feed port of the next fiber dispersion-flotation extraction unit.

4. The grease purification device as described in claim 1, characterized in that, The extraction tank is provided with a first support porous plate and a second support porous plate located above and below the porous fiber layer, respectively; The porous fiber layer is located between the first supporting porous plate and the second supporting porous plate, and the side wall of the extraction tank is hollowed out at the location corresponding to the porous fiber layer; The extraction tank is fitted with a sleeve at the corresponding hollow part, and the sleeve is detachably and fixedly connected to the side wall of the extraction tank. Both the first and second perforated support plates have multiple holes with a diameter of 0.2 to 10 mm and an opening rate of 20% to 90%. The porous fiber layer is fitted with a sealing ring, and the porous fiber layer can be removed from the cutout.

5. The grease purification device as described in claim 3, characterized in that, The final fiber dispersion-float extraction unit also includes a phase separation tank; The phase separation tank is equipped with fiber coalescing packing material, which is made of hydrophilic fibers through weaving. The phase separation tank is connected to the upper end of the oil phase storage tank. The lower end of the phase separation tank is provided with a water phase outlet, and the upper end is provided with an oil phase outlet.

6. The grease purification device as described in claim 1, characterized in that, The porous fiber layer is made of at least one of the following: polypropylene fiber, polytetrafluoroethylene fiber, polyester fiber, glass fiber, stainless steel fiber felt, titanium fiber felt, carbon fiber felt, nickel foam, titanium foam, copper foam, and conductive carbon felt.

7. The grease purification device as described in claim 6, characterized in that, If the porous fiber layer is made of a conductive material, the grease purification device further includes an electrochemical regeneration unit for electrochemically regenerating the porous fiber layer. The electrochemical regeneration unit includes: An electrolytic cell, wherein a diaphragm, an anode, and a cathode are provided inside the electrolytic cell, wherein the cathode is a porous fiber layer; A power source, which is used to connect the anode and cathode; An electrolyte storage tank, which is connected to the electrolytic cell and is used to introduce electrolyte into the electrolytic cell; A hydrogen collection tank, which is connected to the electrolyzer and is used to collect hydrogen generated during the regeneration process; An oil spill containment tank is connected to the electrolytic cell and is used to collect oil spills generated during the regeneration process.

8. A method for purifying oils based on multi-level gradient fiber dispersion-float extraction, applied to the oil purification apparatus based on multi-level gradient fiber dispersion-float extraction as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The aqueous phase enters the extraction tank through the first aqueous phase inlet / outlet of the first fiber dispersion-flotation extraction unit; The oil passes through the oil inlet of the first fiber dispersion-float extraction unit and enters the extraction tank through the porous fiber layer; The aqueous phase and oil are extracted in an extraction tank to complete the first extraction. After separation, the oil after the first extraction is obtained. After the first extraction, the oil passes through the oil inlet of the second fiber dispersion-float extraction unit, enters the extraction tank through the porous fiber layer, and is extracted in the extraction tank of the second fiber dispersion-float extraction unit. This completes the second extraction, separation, and yields the oil after the second extraction. Repeat the above steps until the oil after the previous extraction is extracted using the last fiber dispersion-float extraction unit; Among them, for any two adjacent fiber dispersion-float extraction units, the oil outlet of the previous fiber dispersion-float extraction unit is connected to the oil inlet of the next fiber dispersion-float extraction unit. The pore size of the porous fiber layer of multiple interconnected fiber dispersion-flotation extraction units gradually decreases.

9. The oil purification method based on multi-level gradient fiber dispersion-float extraction as described in claim 8, characterized in that, The aqueous phase includes water, acidic aqueous solution, and aqueous solution containing a complexing agent; The acid in the acidic aqueous solution is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, citric acid, oxalic acid, and lactic acid, and the concentration of the acid in the acidic aqueous solution is 0.001~2 mol / L; The complexing agent in the aqueous solution is selected from one or more of citrate, acetate, EDTA, DTPA, NTA, aminocarboxylic acid compounds or their salts, and the concentration of the complexing agent in the aqueous solution is 0.0001~1 mol / L; The extraction temperature is 20~95℃; The flow rate of the oil entering the extraction tank through the oil inlet through the porous fiber layer is 1~500 mL / min; The flow rate of the aqueous phase entering the extraction tank through the first aqueous phase inlet / outlet is 1~5000 mL / min.

10. The oil purification method based on multi-level gradient fiber dispersion-flotation extraction as described in claim 8, characterized in that, This also includes the regeneration of the porous fiber layer, specifically: Remove the porous fiber layer to be regenerated and place it in the electrolytic cell of the electrochemical regeneration unit. When the porous fiber layer is a conductive material, use it as the cathode and connect it to the negative terminal of the power supply, connect the anode to the positive terminal of the power supply, and introduce electrolyte into the electrolytic cell. Maintain a voltage of 1–30 V and a current density of 1–200 mA / cm². 2 Electrolysis for 1~60 min; The electrolyte includes at least one of sodium sulfate solution, sodium chloride solution, sodium carbonate solution, sodium hydroxide solution, sulfuric acid solution, hydrochloric acid solution, and citric acid solution. The electrolyte concentration is 0.001~1 mol / L.

Images