A tank cleaning oil-electric desalination and dehydration equipment and method

Abstract

This invention provides an electrostatic desalting and dehydration device and method for tank washing oil. The device includes two or more electrostatic desalting tanks, an emulsifier tank, and a water storage tank. The emulsifier tank is connected to the oil inlet of each electrostatic desalting tank via a corresponding demulsifier pipeline. Each electrostatic desalting tank's oil inlet is connected to an incoming oil pipeline, and each electrostatic desalting tank's oil outlet is connected to an external oil export pipeline. The electrostatic desalting tanks are connected in series or in parallel. Each electrostatic desalting tank's incoming oil pipeline is connected to a heat exchanger, a mixer, and a high-frequency induction heating coil. The mixer is located downstream of the heat exchanger, and the high-frequency induction heating coil is also located downstream of the mixer. The high-frequency induction heating coil is connected in series in the loop between the power control cabinet and the transformer to further assist in heating the mixture after it has been heated by the heat exchanger. The high-frequency induction heating coil assists in heating, improving the desalting and dehydration effect and limiting the peak current output of the transformer primary side. This device can adjust its unit processing capacity according to the salt content and water content of the tank washing oil.

Description

Technical Field

[0001] This invention relates to the field of tank cleaning oil treatment technology, and in particular to a tank cleaning oil electrostatic desalination and dehydration equipment and method. Background Technology

[0002] With the rapid development of global industry, the demand for petroleum resources is constantly increasing worldwide. However, as a non-renewable natural resource, petroleum is becoming increasingly scarce due to continuous extraction. Simultaneously, shipping volume is growing rapidly, and offshore oil fields are expanding daily. During cargo loading and unloading, some cargo often remains on the bottom of the cargo holds, bulkheads, fairings, and ship structures. During navigation, oil leaks, spills, or oil pollution caused by mechanical failures can also occur. Therefore, when cleaning cargo holds, these residues and oil contaminants combine with the cleaning water to form large quantities of tank cleaning oil. The worst types of oil have a salt content as high as 1200 mg NaCl / L and a water content of up to 25% wt. Furthermore, they contain high levels of gum, asphaltene, nitrogen, and sulfur. If discharged directly or exceeding standards into water bodies, they will cause serious pollution to marine and river environments, making desalination and dehydration treatment of tank cleaning oil urgently necessary.

[0003] Tank washing oil separation and treatment processes include tank washing oil dehydration and desalination. Typically, after electro-desalination, the oil content must be ≤3 mg / L, the water content ≤0.2%, and the discharged wastewater oil content ≤150 ppm. The tank washing oil electro-desalination and dehydration process usually requires an electro-desalter and an electro-dehydrator. The electro-desalter can be considered as an electro-dehydrator with added dilution water injection and oil-water mixing equipment.

[0004] In existing tank washing oil separation and treatment devices, the oil to be treated mixed with water is passed into a separator for separation.

[0005] The applicant has discovered that the prior art has at least the following technical problems: the existing tank washing oil separation and treatment device cannot adjust the amount of oil processed per unit time according to the salt content and water content in the oil, resulting in energy loss or low processing efficiency; and the temperature of the tank washing oil entering the separator is low, resulting in poor desalination and dehydration of the tank washing oil. Summary of the Invention

[0006] The purpose of this invention is to provide an electro-desalination and dehydration device and method for tank washing oil, in order to solve the technical problems existing in the prior art where the temperature of the tank washing oil entering the tank washing oil separation and treatment device is too low, and the tank washing oil separation and treatment device cannot adjust the processing capacity of the oil per unit time according to the salt content and water content in the oil. 。 The preferred technical solutions among the many technical solutions provided by this invention can produce a variety of technical effects, which are described in detail below.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The tank cleaning oil electro-desalination and dehydration equipment provided by this invention includes two or more electro-desalination tanks, an emulsifier tank, and a water storage tank, wherein:

[0009] The emulsifier tank is connected to the oil inlet of each of the electro-desalting tanks via a corresponding demulsifier pipeline;

[0010] The water storage tank is connected to the oil inlet of the corresponding electric desalination tank through a water injection pipeline, or the water outlet of the latter electric desalination tank is connected to the oil inlet of the former electric desalination tank through a return water pipeline.

[0011] Each of the electric desalting tanks has an oil inlet connected to an oil supply pipeline, and each of the electric desalting tanks has an oil outlet connected to an external oil supply pipeline. The electric desalting tanks are connected in series or in parallel.

[0012] Preferably, each of the electric desalting tanks has a heat exchanger, a mixer, and a high-frequency induction heating coil connected to its oil inlet pipeline. The heat exchanger is used to heat the mixture of oil, water, and demulsifier. The mixer is located downstream of the heat exchanger, and the high-frequency induction heating coil is located downstream of the mixer. The high-frequency induction heating coil is connected in series in the loop of the power control cabinet and the transformer to further assist in heating the mixture after it has been heated by the heat exchanger.

[0013] Preferably, in the series-connected desalting tanks, along the oil flow direction, the oil inlet pipeline of the first desalting tank is directly connected to the tank washing oil source, and the oil outlet pipeline of the preceding desalting tank is connected to the oil inlet pipeline of the following desalting tank.

[0014] In the parallel state of the electric desalting tanks, the oil inlet pipelines of all the electric desalting tanks are directly connected to the washing tank oil source, and the oil outlet pipelines of all the electric desalting tanks are connected.

[0015] Preferably, the electro-desalination tank includes a primary electro-desalination tank, a secondary electro-desalination tank, and a tertiary electro-desalination tank. The primary, secondary, and tertiary electro-desalination tanks are connected in series, or the primary and secondary electro-desalination tanks are connected in parallel and in series with the tertiary electro-desalination tank, or the primary, secondary, and tertiary electro-desalination tanks are connected in parallel.

[0016] Preferably, the oil supply pipeline includes a first oil supply pipeline, a second oil supply pipeline, and a third oil supply pipeline that are respectively connected to the oil inlet of the first-stage electric desalting tank, the oil inlet of the second-stage electric desalting tank, and the oil inlet of the third-stage electric desalting tank;

[0017] The external oil pipeline includes a first external oil pipeline, a second external oil pipeline, and a third external oil pipeline, which are respectively connected to the oil outlet of the first-stage electric desalting tank, the oil outlet of the second-stage electric desalting tank, and the oil outlet of the third-stage electric desalting tank.

[0018] in:

[0019] The first oil inlet pipeline is connected to the tank washing oil source, the first oil outlet pipeline is connected to the second oil inlet pipeline, and the second oil outlet pipeline is connected to the third oil inlet pipeline.

[0020] Alternatively, the first oil inlet pipeline and the second oil inlet pipeline are both connected to the tank washing oil source, and the first external oil outlet pipeline and the second external oil outlet pipeline are both connected to the third oil inlet pipeline.

[0021] Alternatively, the first oil inlet pipeline, the second oil inlet pipeline, and the third oil inlet pipeline are all connected to the tank washing oil source, and the first external oil outlet pipeline, the second external oil outlet pipeline, and the third external oil outlet pipeline are all connected to the next oil processing unit.

[0022] Preferably, the return water pipeline includes a first return water pipeline, a second return water pipeline, and a third return water pipeline, which are respectively connected to the outlets of the primary electro-desalination tank, the secondary electro-desalination tank, and the tertiary electro-desalination tank, wherein:

[0023] When the primary desalination tank, the secondary desalination tank, and the tertiary desalination tank are connected in series, the second return water pipeline is connected to the first oil inlet pipeline, the third return water pipeline is connected to the second oil inlet pipeline, and the first return water pipeline is connected to the sewage treatment equipment.

[0024] When the primary desalination tank and the secondary desalination tank are connected in parallel and the tertiary desalination tank is connected in series, the third return water pipeline is connected to the first oil inlet pipeline and the second oil inlet pipeline, and the first return water pipeline and the second return water pipeline are both connected to the sewage treatment equipment.

[0025] When the primary desalination tank, the secondary desalination tank, and the tertiary desalination tank are connected in parallel, the water storage tank is connected to the first oil inlet pipe, the second oil inlet pipe, and the third oil inlet pipe through the first water inlet pipe, the second water inlet pipe, and the third oil inlet pipe, respectively, and the second return water pipe, the third return water pipe, and the first return water pipe are all connected to the sewage treatment equipment.

[0026] Preferably, the electro-desalination tank is provided with electrode plates, which are vertically arranged, and the electrode plates electrically connected to the positive terminal of the power supply and the electrode plates electrically connected to the negative terminal of the power supply are arranged at intervals along the length of the electro-desalination tank.

[0027] Preferably, a high-frequency AC pulse electric field is formed in the primary desalination tank and the secondary desalination tank, and a high-frequency AC / DC pulse electric field is formed in the tertiary desalination tank.

[0028] Preferably, each of the electric desalting tanks is provided with a crude oil distributor at the bottom of its inner cavity, and the oil supply pipeline is connected to the crude oil distributor.

[0029] The present invention also provides a method for tank cleaning oil electro-desalination and dehydration, using the above-mentioned tank cleaning oil electro-desalination and dehydration equipment, the method comprising:

[0030] The processing efficiency is adjusted by controlling whether the electric desalting tanks are connected in series or in parallel according to the salt content and water content in the tank washing oil.

[0031] The tank washing oil to be treated is mixed with the demulsifier in the demulsifier pipeline, so that the water storage tank is connected to the oil inlet of the corresponding electric desalting tank through the water injection pipeline, or the water outlet of the latter electric desalting tank is connected to the oil inlet of the former electric desalting tank through the return water pipeline.

[0032] The mixture is heated sequentially by the heat exchanger and the high-frequency induction heating coil, and then injected into all the electric desalination tanks that are connected in series or in parallel. After being treated by a high-frequency AC pulse electric field, the saline wastewater settles to the bottom of the tank and is discharged to the wastewater treatment equipment.

[0033] Preferably, the electrostatic desalination tank includes a primary electrostatic desalination tank, a secondary electrostatic desalination tank, and a tertiary electrostatic desalination tank;

[0034] When the salt content and water content in the tank cleaning oil are higher than the first set amount, the first-stage electric desalting tank, the second-stage electric desalting tank and the third-stage electric desalting tank are connected in series, so that the tank cleaning oil to be treated is mixed with demulsifier and water, and then heated by the heat exchanger and the high-frequency induction heating coil in sequence, and then flows through the first-stage electric desalting tank, the second-stage electric desalting tank and the third-stage electric desalting tank in sequence for treatment;

[0035] When the salt content and water content in the tank cleaning oil are higher than the second set amount but lower than the first set amount, the first-stage electric desalting tank and the second-stage electric desalting tank are connected in parallel and connected in series with the third-stage electric desalting tank. The tank cleaning oil to be treated is mixed with demulsifier and water, and then heated sequentially by the heat exchanger and the high-frequency induction heating coil. After flowing through the first-stage electric desalting tank and the second-stage electric desalting tank, it flows into the third-stage electric desalting tank for treatment. The second set amount is lower than the first set amount.

[0036] When the salt content and water content in the tank cleaning oil are less than the second set amount, the primary electric desalting tank, the secondary electric desalting tank, and the tertiary electric desalting tank are connected in parallel. The tank cleaning oil to be treated is mixed with demulsifier and water, and then heated sequentially by the heat exchanger and the high-frequency induction heating coil before flowing through the parallel primary electric desalting tank, the secondary electric desalting tank, and the tertiary electric desalting tank for treatment.

[0037] The electrostatic desalting and dehydration equipment and method for tank washing oil provided by this invention has the following advantages compared with the prior art: It sets up two or more electrostatic desalting tanks. Under the synergistic effect of an electric field, high temperature, and chemical demulsifier, the dispersed water particles in the tank washing oil aggregate and grow, then settle to the bottom of the electrostatic desalting tank by gravity and separate, thereby achieving the purpose of dehydration and desalination. The electrostatic desalting tanks can be controlled to be connected in series or in parallel according to the salt content and water content in the tank washing oil, thereby adjusting the oil processing capacity per unit time. When the salt content and water content in the tank washing oil are high, the electrostatic desalting tanks are connected in series; when the salt content and water content are low, the electrostatic desalting tanks are connected in parallel. A high-frequency induction heating coil is fitted outside the oil inlet pipeline of each stage of the electrostatic desalting tank, which can further assist in heating the tank washing oil mixture after it has been heated by the heat exchanger, improving the desalination and dehydration effect. Furthermore, the high-frequency induction heating coil also has the function of limiting the peak output current of the transformer primary side.

[0038] The equipment and method for desalting and dehydrating tank cleaning oil can adjust its unit processing capacity according to the salt content and water content of the tank cleaning oil, ensuring the efficiency of salt and water treatment in the tank cleaning oil and reducing the cost of tank cleaning oil treatment. Attached Figure Description

[0039] 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.

[0040] Figure 1 This is a schematic diagram of the overall structure of the tank cleaning, oil-electric desalination, and dehydration equipment;

[0041] Figure 2 This is a schematic diagram of the structure when a primary electrostatic desalination tank, a secondary electrostatic desalination tank, and a tertiary electrostatic desalination tank are connected in series.

[0042] Figure 3 This is a schematic diagram of the structure when the primary and secondary electric desalination tanks are connected in parallel and connected in series with the tertiary electric desalination tank.

[0043] Figure 4 This is a schematic diagram of the structure when a primary, secondary, and tertiary electrostatic desalination tank are connected in parallel.

[0044] Figure 5 This is a schematic diagram of the structure of a primary electric desalination tank;

[0045] Figure 6 This is a schematic diagram of the structure of a two-stage electric desalination tank;

[0046] Figure 7 This is a schematic diagram of a three-stage electric desalination tank.

[0047] In the diagram: D1001, Primary electrostatic desalination tank; D1002, Secondary electrostatic desalination tank; D1003, Tertiary electrostatic desalination tank; D1101, Emulsifier tank; D1102, Water storage tank; D1103, Wastewater treatment equipment; 1, Oil phase layer; 2, Emulsion layer; 3, Aqueous phase layer; 4, First oil inlet pipeline; 5, Demulsifier pipeline; 6, Second return water pipeline; 7, Mixer; 8, Mixing valve; 9, Crude oil distributor; 10, High-voltage electrode plate; 11, Grounding electrode plate; 12, Transformer; 13, Power control cabinet; 14, Electrode plate; 15, DC high-voltage electric field; 6. DC medium electric field; 17. AC weak electric field; 18. Oil-water interface; 19. Backwasher; 20. Drain pipe; 21. Sediment flushing manifold; 22. Crude oil outlet manifold; 23. First external oil pipeline; 24. High-frequency induction heating coil; 25. Second external oil pipeline; 26. Third external oil pipeline; 27. Third return water pipeline; 28. Third water injection pipeline; 29. ​​Rectifier diode; 30. Heat exchanger; 31. Second incoming oil pipeline; 32. Third incoming oil pipeline; 33. First return water pipeline; 34. First water injection pipeline; 35. Second water injection pipeline. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] In the description of this invention, it should be understood that the terms "center," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0050] This invention provides an electro-desalination and dehydration device for tank cleaning oil, which can adjust the processing capacity according to the salt content and water content of the tank cleaning oil, ensuring the treatment efficiency of salt and water in the tank cleaning oil and reducing the cost of tank cleaning oil treatment.

[0051] The following is combined Figures 1-7 The technical solution provided by this invention will be described in more detail below.

[0052] The present invention provides an electrostatic desalting and dehydration device for tank cleaning oil, comprising two or more electrostatic desalting tanks, an emulsifier tank D1101, and a water storage tank D1102, wherein: the emulsifier tank D1101 is connected to the oil inlet of each electrostatic desalting tank via a corresponding demulsifier pipeline 5; the water storage tank D1102 is connected to the oil inlet of the corresponding electrostatic desalting tank via a water injection pipeline, or the outlet of the subsequent electrostatic desalting tank is connected to the oil inlet of the preceding electrostatic desalting tank via a return water pipeline; the oil inlet of each electrostatic desalting tank is connected to a... The oil pipeline system connects the oil outlet of each electrostatic desalination tank to an external oil supply pipeline. The electrostatic desalination tanks can be connected in series or in parallel. In the series connection, along the oil flow direction, the oil supply pipeline of the first electrostatic desalination tank is directly connected to the tank washing oil source, and the external oil supply pipeline of the preceding electrostatic desalination tank is connected to the oil supply pipeline of the following electrostatic desalination tank. In the parallel connection, the oil supply pipelines of all electrostatic desalination tanks are directly connected to the tank washing oil source, and the external oil supply pipelines of all electrostatic desalination tanks are connected.

[0053] The structure of the electrostatic desalination tank will be explained below:

[0054] See Figures 5-7 As shown, each electric desalting tank has a heat exchanger 30, a mixer 7, and a high-frequency induction heating coil 24 connected to its oil inlet pipeline. The heat exchanger 30 is used to heat the mixture of oil, water, and demulsifier. The mixer 7 is located downstream of the heat exchanger 30. The high-frequency induction heating coil 24 is located downstream of the mixer 7. The high-frequency induction heating coil 24 is connected in series in the loop between the power control cabinet 13 and the transformer 12 to further assist in heating the mixture after it has been heated by the heat exchanger 30.

[0055] When the washing oil, demulsifier and water mixture is running in the washing tank desalting and dehydration equipment, the high-frequency induction heating coil 24 heats the mixture formed by washing oil, demulsifier and water to a certain temperature through heat exchanger 30, and then further assists in heating it into each stage of electric desalting tank D1001 through this high-frequency induction heating coil 24. The high-frequency induction heating coil 24 is connected in series between the output port of power control cabinet 13 and the primary input port of transformer 12. This high-frequency induction heating coil 24 also has the function of limiting the peak output current of the primary side of transformer 12.

[0056] The power control cabinet 13 provides a high-frequency / high-voltage pulsed AC power supply. The electric field parameters of this power supply can be set according to the physicochemical properties of the crude oil and intermediate oil-water emulsion being processed. The optimal electric field parameters can be set based on the water content of the tank washing oil. The voltage of its power system can be steplessly adjusted within the range of 0–20kV, the frequency within the range of 50–5000Hz, and the duty cycle within the range of 10%–90%. The waveform can be switched between sawtooth waves, triangular waves, and pulsed square waves.

[0057] The oil inlet pipeline carries a mixture of tank washing oil, dilution water, and demulsifier into the electrostatic desalting tank via static mixing valve 8. Inside the electrostatic desalting tank, from top to bottom, are the oil phase layer 1, the emulsion layer 2, and the aqueous phase layer 3.

[0058] The high-frequency induction heating coil 24 is connected in series in the loop between the power control cabinet 13 and the transformer 12. The high-frequency induction heating coil 24 can not only assist in heating the mixture, but also limit the peak output current of the primary side of the transformer 12.

[0059] The high-frequency induction heating coil 24 is installed on the outside of the oil inlet pipeline of each stage of electric desalting tank, which can further assist in heating the tank washing oil mixture after it has been heated by the heat exchanger, thereby improving the desalting and dehydration effect; and the high-frequency induction heating coil also has the function of limiting the peak output current of the transformer primary side.

[0060] The electrostatic desalting tank generates an electric field. During electrostatic desalting, the heated tank washing oil produced fluid is mixed with dilution water in a specific ratio. This mixture is then passed through a mixing and shearing device to form a homogeneous oil-water mixture with a low to medium water content. Most of the inorganic salts carried in the tank washing oil are extracted and transferred to the dilution water during this process. The homogeneous oil-water mixture then enters the electrostatic desalting tank. Under the synergistic effect of the electric field, high temperature, and chemical demulsifier, the dispersed water particles aggregate and grow, then settle to the bottom of the separator under gravity, achieving dehydration and desalination. After thorough desalting and dehydration of the tank washing oil, the crude oil can be recycled, saving resources and better protecting the environment.

[0061] The tank washing oil electrostatic desalination and dehydration equipment in this embodiment is equipped with two or more electrostatic desalination tanks. Under the synergistic effect of electric field, high temperature and chemical demulsifier, the dispersed phase water particles in the tank washing oil aggregate and grow, and then settle to the bottom of the electrostatic desalination tank by gravity and separate out, thereby achieving the purpose of dehydration and desalination. The electrostatic desalination tanks can be controlled to be in series or parallel according to the salt content and water content in the tank washing oil, thereby adjusting the oil processing capacity per unit time. When the salt content and water content in the tank washing oil are high, the electrostatic desalination tanks are controlled to be in series, and when the salt content and water content in the tank washing oil are low, the electrostatic desalination tanks are controlled to be in parallel.

[0062] As an optional embodiment, an electrode plate 14 is provided inside the electro-desalination tank. The electrode plate 14 is vertically arranged, and the electrode plate 14 electrically connected to the positive terminal of the power supply and the electrode plate 14 electrically connected to the negative terminal of the power supply are arranged at intervals along the length direction of the electro-desalination tank.

[0063] A high-frequency / high-voltage pulse AC power supply is used in conjunction with a vertically mounted variable-gap electrode plate 14 to form an electric field inside the electric desalting tank; the oil inlet pipeline is located at the bottom of the electric desalting tank and connected to the crude oil distributor 9 inside the electric desalting tank, and a demulsifying electrode is located above the crude oil distributor 9.

[0064] In this embodiment, see Figures 1-4 As shown, the electrostatic desalination tank includes a primary electrostatic desalination tank D1001, a secondary electrostatic desalination tank D1002, and a tertiary electrostatic desalination tank D1003. The primary electrostatic desalination tanks D1001, D1002, and D1003 are connected in series, or the primary electrostatic desalination tanks D1001 and D1002 are connected in parallel and connected in series with the tertiary electrostatic desalination tank D1003, or the primary electrostatic desalination tanks D1001, D1002, and D1003 are connected in parallel.

[0065] See Figure 5 and Figure 6 As shown, a high-frequency AC pulsed electric field is formed inside the primary electrostatic desalination tank and the secondary electrostatic desalination tank. (See attached image.) Figure 7 As shown, a high-frequency AC / DC pulsed electric field is formed inside the three-stage electro-desalting tank.

[0066] This configuration reduces the likelihood of short-circuit breakdown between the electrodes, improving the reliability and stability of the equipment. It also enhances the effect of the electric field, significantly improving the processing performance of the electrostatic desalination unit.

[0067] All electrode plates 14 electrically connected to the positive terminal of the power supply are electrically connected to the high-voltage electrode plate 10, and all electrode plates 14 electrically connected to the negative terminal of the power supply are electrically connected to the ground electrode plate 11. See also Figure 7 As shown, transformer 12 is electrically connected to rectifier diode 29, forming an AC / DC electric field inside the three-stage desalination tank.

[0068] See Figures 5-7 As shown, within the corresponding electrostatic desalting tank, under the influence of an electric field, there exist, from top to bottom, an oil phase layer 1, an emulsion layer 2, and an aqueous phase layer 3. An oil-water interface 18 exists between the emulsion layer 2 and the aqueous phase layer 3. The aqueous phase layer is connected to a drain pipe 20 via a backwasher 19 and a sediment flushing manifold 21. The oil phase layer 1 is connected to the corresponding external oil pipeline via a crude oil outlet manifold 22.

[0069] Specifically, when the salt and water content of the washing oil is high, the primary desalting tank D1001, the secondary desalting tank D1002, and the tertiary desalting tank D1003 are connected in series; when the salt and water content of the washing oil is slightly high, the primary desalting tank D1001 and the secondary desalting tank D1002 are connected in parallel and connected in series with the tertiary desalting tank D1003; when the salt and water content of the washing oil is low, the primary desalting tank D1001, the secondary desalting tank D1002, and the tertiary desalting tank D1003 are connected in parallel.

[0070] This configuration allows the tank cleaning oil desalination and dehydration equipment to adjust its processing capacity based on the salt and water content of the tank cleaning oil, ensuring efficient treatment of salt and water and reducing the cost of tank cleaning oil treatment. Specifically, it prevents the difficulty in effectively treating salt in the oil when the salt and water content is high, and also prevents high costs and energy waste caused by using a larger capacity device when the salt and water content of the tank cleaning oil is low.

[0071] See Figures 1-4 As shown, the oil inlet pipeline is for the input of a mixture of oil, demulsifier, and water to the corresponding electrostatic desalting tank. The oil inlet pipeline includes a first oil inlet pipeline 4, a second oil inlet pipeline 31, and a third oil inlet pipeline 32, which are respectively connected to the oil inlet of the first-stage electrostatic desalting tank D1001, the oil inlet of the second-stage electrostatic desalting tank D1002, and the oil inlet of the third-stage electrostatic desalting tank D1003.

[0072] See Figures 1-4 As shown, the external oil pipeline transports the oil processed by the corresponding electrostatic desalination tank to the outside. The external oil pipeline includes a first external oil pipeline 23, a second external oil pipeline 25, and a third external oil pipeline 26, which are respectively connected to the oil outlet of the first-stage electrostatic desalination tank D1001, the oil outlet of the second-stage electrostatic desalination tank D1002, and the oil outlet of the third-stage electrostatic desalination tank D1003.

[0073] See Figures 1-4 As shown, the return water pipeline connects the water obtained after treatment in the corresponding electrostatic desalination tank to the previous stage electrostatic desalination tank D1001, thereby saving water resources; or, it connects the water obtained after treatment in the corresponding electrostatic desalination tank to the wastewater treatment equipment D1103. The return water pipeline includes a first return water pipeline 33, a second return water pipeline 6, and a third return water pipeline 27, which are respectively connected to the outlets of the first-stage electrostatic desalination tank D1001, the second-stage electrostatic desalination tank D1002, and the third-stage electrostatic desalination tank D1003.

[0074] Example 1:

[0075] In this embodiment, the primary desalting tank D1001, the secondary desalting tank D1002, and the tertiary desalting tank D1003 are connected in series, which is suitable for treating tank washing oil with high salt and water content.

[0076] Figure 2To clearly illustrate the state when the primary electrostatic desalination tank D1001, the secondary electrostatic desalination tank D1002, and the tertiary electrostatic desalination tank D1003 are connected in series, the following will be shown: Figure 1 The pipelines for unloading (pipelines with valves closed) are omitted.

[0077] See Figure 2 As shown, Figure 2 and Figure 1 In comparison, the first oil inlet pipeline 4 is connected to the tank washing oil source, the first external oil outlet pipeline 23 is connected to the second oil inlet pipeline 31, and the second external oil outlet pipeline 25 is connected to the third oil inlet pipeline 32. The second return water pipeline 6 is connected to the first oil inlet pipeline 4, the third return water pipeline 27 is connected to the second oil inlet pipeline 31, and the first return water pipeline 33 is connected to the sewage treatment equipment D1103.

[0078] For details, see Figure 1 and Figure 2 As shown, valve FIC1015 on the pipeline between the secondary electric desalting tank D1002 and the tank washing oil source is closed, valve FIC1011 on the first external oil supply pipeline 23 is opened, and valve FIC1013 on the pipeline between the first external oil supply pipeline 23 and the second external oil supply pipeline 25 is closed; valve FIC1016 on the pipeline between the tertiary electric desalting tank D1003 and the tank washing oil source is closed, valve FIC1012 on the pipeline between the second external oil supply pipeline 25 and the third incoming oil pipeline 32 is opened, valve FIC1014 on the pipeline between the second external oil supply pipeline 25 and the third external oil supply pipeline 26 is closed, valve FIC1004 on the third water injection pipeline 28 is opened, valve FIC1008 on the third return water pipeline 27 is opened, valve FIC1009 on the second return water pipeline 6 is closed, and valve FIC1017 on the pipeline between the third return water pipeline 27 and the first incoming oil pipeline 4 is closed. The FIC1005 valve on the second water injection line 35 is closed, the FIC1007 valve between the second return water line 6 and the first oil inlet line 4 is opened, the FIC1010 valve on the first return water line 33 is closed, and the FIC1006 valve on the first water injection line 34 is closed, forming a three-stage electrostatic desalting system. At this time, the first-stage electrostatic desalting tank D1001, the second-stage electrostatic desalting tank D1002, and the third-stage electrostatic desalting tank D1003 are connected in series to treat tank washing oil with high salt and water content.

[0079] The tank washing oil to be treated in the crude oil pipeline is mixed with the demulsifier in the demulsifier pipeline, and then mixed with dilution water from the second return water pipeline 6. After being heated by the heat exchanger 30, it is fully mixed under the action of the static mixer 7 and the mixing valve 8. After being further heated by the high-frequency induction heating coil, it enters the bottom inlet of the first-stage electric desalting tank D1001. During the mixing process, the dilution water extracts the salt in the crude oil. The oil-water mixture is distributed to the vicinity of the electric field action area of ​​the electric desalting tank through the bottom crude oil distributor 9. Desalination and dehydration occur in the primary electrostatic desalination tank D1001. After being treated by the high-frequency, high-voltage AC electric field provided by the primary electrostatic desalination tank D1001, the saline wastewater settles to the bottom of the tank and is discharged outside the tank to the wastewater treatment device through drain pipe 20. The tank washing oil treated by the primary electrostatic desalination tank D1001 comes out from the first external oil pipe 23 at the top of the primary electrostatic desalination tank D1001 and mixes with the circulating water in the third return water pipe 27 of the tertiary electrostatic desalination tank D1003 and the demulsifier in the demulsifier pipe. The mixture is then heated by heat exchanger 30. Afterwards, the mixture is fully mixed under the action of static mixer 7 and mixing valve 8, and then further heated by high-frequency induction heating coil 24 before entering the secondary electric desalination tank D1002 for desalination and dewatering. After being treated by the high-frequency high-voltage AC electric field provided by the secondary electric desalination tank D1002, the saline wastewater settles to the bottom of the secondary electric desalination tank D1002 and is discharged outside the tank through the second return water pipeline 6 of the secondary electric desalination tank D1002. After being pressurized by the primary circulating water injection pump P105, it is reinjected back to the mixing valve 8 of the primary electric desalination tank D1001. The treated tank washing oil exits from the top of the secondary electric desalination tank D1002, where it mixes with water from the third water injection line 28 of the tertiary water injection pump P103 and demulsifier from the demulsifier line. After being heated by the heat exchanger 30, it is thoroughly mixed under the action of the static mixer 7 and the mixing valve 8. Then, after being assisted by the high-frequency induction heating coil 24, it enters the tertiary electric desalination tank D1003. The mixture sequentially passes through the AC weak electric field 17, the DC medium electric field 16, and the DC strong electric field 15 for desalination and dehydration. The saline wastewater settles to the bottom of the electric desalination tank and is pressurized by the secondary circulating water injection pump P104 before being injected into the mixing valve 8 of the secondary electric desalination tank D1002. The treated tank washing oil exits from the third external oil pipeline 26 at the top of the tertiary desalination tank and proceeds to the subsequent processing unit.

[0080] Example 2:

[0081] The difference between Example 2 and Example 1 is as follows: See Figure 1 and Figure 3 As shown, Figure 3 To clearly illustrate the state when the primary electrostatic desalination tank D1001 and the secondary electrostatic desalination tank D1002 are connected in parallel and then connected in series with the tertiary electrostatic desalination tank D1003, the following will be shown: Figure 1 The pipelines for unloading (pipelines with valves closed) are omitted.

[0082] In this embodiment, the primary desalting tank D1001 and the secondary desalting tank D1002 are connected in parallel and connected in series with the tertiary desalting tank D1003, which is suitable for treating tank washing oil with slightly high salt and water content.

[0083] The first oil inlet pipeline 4 and the second oil inlet pipeline 31 are both connected to the tank washing oil source; the first external oil outlet pipeline 23 and the second external oil outlet pipeline 25 are both connected to the third oil inlet pipeline 32; the third return water pipeline 27 is connected to the first oil inlet pipeline 4 and the second oil inlet pipeline 31; the first return water pipeline 33 and the second return water pipeline 6 are both connected to the sewage treatment equipment D1103.

[0084] Specifically, such as Figure 3 As shown, the FIC1015 valve on the pipeline between the secondary electric desalting tank D1002 and the tank washing oil source is opened, the FIC1011 valve on the first external oil supply pipeline 23 is closed, and the FIC1013 valve on the pipeline between the first external oil supply pipeline 23 and the second external oil supply pipeline 25 is opened; the FIC1016 valve on the pipeline between the tertiary electric desalting tank D1003 and the tank washing oil source is closed, the FIC1012 valve on the pipeline between the second external oil supply pipeline 25 and the third incoming oil pipeline 32 is opened, the FIC1014 valve on the pipeline between the second external oil supply pipeline 25 and the third external oil supply pipeline 26 is closed, the FIC1004 valve on the third water injection pipeline 28 is opened, the FIC1008 valve on the third return water pipeline 27 is opened, the FIC1009 valve on the second return water pipeline 6 is closed, and the FIC1017 valve on the pipeline between the third return water pipeline 27 and the first incoming oil pipeline 4 is opened. When the FIC1005 valve on the second water injection line 35 is closed, the FIC1007 valve between the second return water line 6 and the first oil supply line 4 is closed, the FIC1010 valve on the first return water line 33 is opened, and the FIC1006 valve on the first water injection line 34 is closed, at this time, the first-stage electric desalting tank D1001 and the second-stage electric desalting tank D1002 are connected in parallel and connected in series with the third-stage electric desalting tank D1003 to treat tank washing oil with slightly higher salt and water content.

[0085] The tank washing oil to be treated is mixed with the demulsifier in the demulsifier line through the first oil inlet line 4 of the primary electric desalting tank D1001 and the second oil inlet line 31 of the secondary electric desalting tank D1002, respectively. Then it is mixed with dilution water in the corresponding water injection line. After being heated by the heat exchanger 30, it is fully mixed under the action of the static mixer 7 and the mixing valve 8. After being further heated by the high-frequency induction heating coil 24, it enters the bottom inlet of the primary electric desalting tank D1001 and the secondary electric desalting tank D1002. During the mixing process, the dilution water extracts the salt in the crude oil. The oil-water mixture is distributed to the vicinity of the electric field action area of ​​the electric desalting unit through the bottom crude oil distributor 9. Desalination and dehydration are carried out in the primary desalination tank D1001 and the secondary desalination tank D1002. After being treated by the high-frequency, high-voltage AC electric field provided by the primary and secondary desalination tanks D1001 and D1002, the saline wastewater settles to the bottom of the desalination tank and is discharged outside the tank to the wastewater treatment device through the drain pipe 20. The treated tank washing oil comes out from the first external oil pipe 23 of the primary desalination tank D1001 and the second external oil pipe 25 on the top of the secondary desalination tank D1002, and enters the third oil inlet pipe 32 of the tertiary desalination tank D1003, where it meets the water and demulsifier in the third water injection pipe 28. The demulsifier in the pipeline is mixed and heated by the heat exchanger 30. Under the action of the static mixer 7 and the mixing valve 8, it is fully mixed and then heated by the high-frequency induction heating coil 24 before entering the three-stage electric desalination tank D1003. The mixture is then desalinated and dehydrated by passing through the AC weak electric field 17, the DC medium electric field 16, and the DC strong electric field 15 in sequence. The saline wastewater settles to the bottom of the three-stage electric desalination tank D1003 and is discharged from the tank to the wastewater treatment device through the drain pipe 20. The treated tank washing oil comes out from the third external oil pipe 26 on the top of the three-stage desalination tank and goes to the subsequent treatment unit.

[0086] Example 3:

[0087] The difference between Example 3 and Example 1 is as follows:

[0088] In this embodiment, the primary desalting tank D1001, the secondary desalting tank D1002, and the tertiary desalting tank D1003 are connected in parallel, which is suitable for processing tank washing oil with low salt content and water content.

[0089] Figure 4 To clearly illustrate the state of the primary electrostatic desalination tank D1001, the secondary electrostatic desalination tank D1002, and the tertiary electrostatic desalination tank D1003 connected in parallel, the following will be shown: Figure 1 The pipelines for unloading (pipelines with valves closed) are omitted.

[0090] See Figure 4As shown, the first oil inlet pipeline 4, the second oil inlet pipeline 31, and the third oil inlet pipeline 32 are all connected to the tank washing oil source, and the first external oil outlet pipeline 23, the second external oil outlet pipeline 25, and the third external oil outlet pipeline 26 are all connected to the next oil processing unit. The water storage tank is connected to the first oil inlet pipeline 4, the second oil inlet pipeline 31, and the third oil inlet pipeline 32 through the first water inlet pipeline 34, the second water inlet pipeline 35, and the third water inlet pipeline 28, respectively, and the second return water pipeline 6, the third return water pipeline 27, and the first return water pipeline 33 are all connected to the sewage treatment equipment D1103.

[0091] For details, see Figure 1 and Figure 4 As shown, the FIC1015 valve on the pipeline between the secondary electric desalting tank D1002 and the tank washing oil source is opened, the FIC1011 valve on the first external oil supply pipeline 23 is closed, and the FIC1013 valve on the pipeline between the first external oil supply pipeline 23 and the second external oil supply pipeline 25 is opened; the FIC1016 valve on the pipeline between the tertiary electric desalting tank D1003 and the tank washing oil source is opened, the FIC1012 valve on the pipeline between the second external oil supply pipeline 25 and the third incoming oil pipeline 32 is closed, the FIC1014 valve on the pipeline between the second external oil supply pipeline 25 and the third external oil supply pipeline 26 is opened, the FIC1004 valve on the third water injection pipeline 28 is opened, the FIC1008 valve on the third return water pipeline 27 is closed, and the FIC1009 valve on the second return water pipeline 6 is opened. The FIC1005 valve on the second water injection pipeline 35 is opened, the FIC1007 valve between the second return water pipeline 6 and the first oil supply pipeline 4 is closed, the FIC1010 valve on the first return water pipeline 33 is opened, and the FIC1006 valve on the first water injection pipeline 34 is opened, forming a single-stage electric desalting system. At this time, the first-stage electric desalting tank D1001, the second-stage electric desalting tank D1002, and the third-stage electric desalting tank D1003 are connected in parallel to treat the washing oil with low salt content and water content.

[0092] The tank washing oil to be treated is mixed with the demulsifier in the corresponding oil inlet pipeline and then with the dilution water in the corresponding water injection pipeline. After being heated by the heat exchanger 30, it is fully mixed under the action of the static mixer 7 and the mixing valve 8. After being further heated by the high-frequency induction heating coil, it enters the bottom inlet of each stage of the electric desalting tank. During the mixing process, the dilution water extracts salt from the crude oil. The oil-water mixture is distributed to the vicinity of the electric field action area of ​​the electric desalting tank by the bottom crude oil distributor 9. Desalting and dehydration are carried out in each stage of the electric desalting tank. After being treated by the high-frequency high-voltage electric field, the saline wastewater settles to the bottom of the electric desalting tank and is discharged from the tank to the wastewater treatment equipment D1103 through the drain pipe 20. The treated tank washing oil comes out from the first external oil outlet pipe 23 of the first-stage electric desalting tank D1001, the second external oil outlet pipe 25 of the second-stage electric desalting tank D1002, and the third external oil outlet pipe 26 of the third-stage electric desalting tank D1003, and goes to the subsequent treatment unit.

[0093] This tank cleaning and desalination equipment has the following advantages:

[0094] (1) The three-stage electro-desalting system enhances the desalting and dehydration effect of the tank cleaning oil, and can remove salt and water from the tank cleaning oil more efficiently.

[0095] (2) Using high-frequency high-voltage AC pulse electric field and high-frequency high-voltage AC-DC pulse electric field can make it less likely for short circuit breakdown to occur between the plates, thus improving the reliability and stability of the equipment. At the same time, it can also enhance the effect of the electric field, thus significantly improving the processing performance of the desalination unit.

[0096] (3) The high-frequency induction heating coil 24 is connected in series in the loop between the power control cabinet 13 and the transformer 12. It can assist in heating the tank washing oil mixture after each stage is heated by the heat exchanger 30. At the same time, it has the function of limiting the peak output current of the primary side of the transformer 12 to protect the stable operation of the equipment.

[0097] (4) By controlling the opening and closing of the control valves between each electric desalting tank, the connection mode of the three electric desalting tanks can be switched, which can increase the processing capacity of the tank washing oil per unit time and reduce the cost of tank washing oil treatment.

[0098] Example 4:

[0099] This embodiment provides a method for tank cleaning oil electro-hydraulic desalination and dehydration using the aforementioned tank cleaning oil electro-hydraulic desalination and dehydration equipment. The method includes:

[0100] The processing efficiency is adjusted by controlling whether the electric desalting tanks are connected in series or in parallel according to the salt content and water content in the tank washing oil.

[0101] The tank washing oil to be treated is mixed with the demulsifier in the demulsifier pipeline 5, so that the water storage tank is connected to the oil inlet of the corresponding electric desalting tank through the water injection pipeline, or the water outlet of the subsequent electric desalting tank is connected to the oil inlet of the previous electric desalting tank through the return water pipeline.

[0102] The mixture is heated sequentially by a heat exchanger and a high-frequency induction heating coil 24, and then injected into all the electric desalination tanks that are connected in series or in parallel. After being treated by a high-frequency AC pulse electric field, the saline wastewater settles to the bottom of the tank and is discharged into the wastewater treatment equipment D1103.

[0103] As an optional implementation, the electrostatic desalination tank includes a primary electrostatic desalination tank D1001, a secondary electrostatic desalination tank D1002, and a tertiary electrostatic desalination tank D1003;

[0104] When the salt content and water content in the tank washing oil are higher than the first set amount, the primary electric desalting tank D1001, the secondary electric desalting tank D1002 and the tertiary electric desalting tank D1003 are connected in series, so that the tank washing oil to be treated is mixed with demulsifier and water, and then heated by the heat exchanger and the high-frequency induction heating coil in sequence, and then flows through the primary electric desalting tank D1001, the secondary electric desalting tank D1002 and the tertiary electric desalting tank D1003 in sequence for treatment;

[0105] When the salt content and water content in the tank washing oil are higher than the second set amount but lower than the first set amount, the primary electric desalting tank D1001 and the secondary electric desalting tank D1002 are connected in parallel and connected in series with the tertiary electric desalting tank D1003. The tank washing oil to be treated is mixed with demulsifier and water, and then heated sequentially through the heat exchanger and the high-frequency induction heating coil. After flowing through the primary electric desalting tank D1001 and the secondary electric desalting tank D1002, it flows into the tertiary electric desalting tank D1003 for treatment. The second set amount is lower than the first set amount.

[0106] When the salt content and water content in the tank cleaning oil are less than the second set amount, the primary electric desalting tank D1001, the secondary electric desalting tank D1002, and the tertiary electric desalting tank D1003 are connected in parallel. The tank cleaning oil to be treated is mixed with demulsifier and water, and then heated sequentially through the heat exchanger and the high-frequency induction heating coil before flowing through the parallel primary electric desalting tank D1001, the secondary electric desalting tank D1002, and the tertiary electric desalting tank D1003 for treatment.

[0107] The first and second settings can be set according to the actual situation, and are not limited here.

[0108] Specifically, the method for desalting and dehydrating tank cleaning oil with high salt and water content is characterized by the following steps:

[0109] When the primary electrostatic desalination tank D1001, the secondary electrostatic desalination tank D1002, and the tertiary electrostatic desalination tank D1003 are connected in series, the following steps are included:

[0110] A. The washing oil to be treated in the crude oil pipeline is mixed with the demulsifier in the demulsifier pipeline. Then, circulating water is injected into the mixture. The mixture is first heated to an appropriate temperature by heat exchanger 30. After passing through static mixer 7 and mixing valve 8, it is further assisted by high-frequency electromagnetic induction heating coil in energy-saving auxiliary heating system. Then, it is injected into the first-stage electric desalting tank D1001. After being treated by the high-frequency AC pulse electric field provided by the first-stage electric desalting tank D1001, the saline wastewater settles to the bottom of the tank and is discharged to the wastewater treatment device.

[0111] B. The washing oil after being treated by the primary desalting tank D1001 is output from the top of the primary desalting tank D1001, mixed with demulsifier and circulating water in the second oil inlet pipeline, and after being heated by heat exchanger 30 and assisted by high-frequency induction heating coil, it enters the secondary desalting tank D1002. After being treated by the high-frequency AC pulse electric field provided by the secondary desalting tank D1002, the saline wastewater flows back to the primary oil inlet pipeline 4 through the second return water pipeline 6.

[0112] C. The washing oil treated by the secondary electric desalting tank D1002 is output from the second external oil supply pipe 25, mixed with demulsifier and dilution water from the third water injection pipe 28, heated by the heat exchanger 30 and assisted by the high-frequency induction heating coil, and then enters the tertiary electric desalting tank D1003. The mixture is then desalted and dehydrated by passing through the AC weak electric field 17, the DC medium electric field 16, and the DC strong electric field 15 in sequence. The saline wastewater is reinjected into the second oil supply pipe 31 through the third return water pipe 27. The treated washing oil comes out from the third external oil supply pipe 26 of the tertiary electric desalting tank D1003 and goes to the subsequent processing unit.

[0113] The primary electrostatic desalination tank D1001 serves as the pretreatment unit for the secondary electrostatic desalination tank D1002, and the secondary electrostatic desalination tank D1002 serves as the pretreatment unit for the tertiary electrostatic desalination tank D1003.

[0114] The demulsifier is pumped to the emulsifier tank via a demulsifier addition pump. The demulsifier, originating from the emulsifier tank, is pressurized by the demulsifier pump and injected before the primary electro-desalination mixing valve 8. Secondary and tertiary electro-desalination mixing valves 8 are also pre-installed. The electro-desalination and dehydration method for tank washing oil in this embodiment can adjust the treatment volume according to the salt and water content of the tank washing oil, ensuring efficient treatment of salt and water in the tank washing oil and reducing the cost of tank washing oil treatment.

[0115] The specific features, structures, or characteristics described in this specification may be combined in any suitable manner in one or more embodiments or examples.

[0116] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0117] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A tank cleaning oil electric desalting and dewatering apparatus, characterized by, Includes two or more electrostatic desalination tanks, emulsifier tanks, and water storage tanks, wherein: The emulsifier tank is connected to the oil inlet of each of the electro-desalting tanks via a corresponding demulsifier pipeline; The water storage tank is connected to the oil inlet of the corresponding electric desalination tank through a water injection pipeline, or the water outlet of the latter electric desalination tank is connected to the oil inlet of the former electric desalination tank through a return water pipeline. Each of the electric desalting tanks has an oil inlet connected to an oil supply pipeline, and each of the electric desalting tanks has an oil outlet connected to an external oil supply pipeline. The electric desalting tanks are connected in series and / or in parallel. Each of the aforementioned electric desalting tanks has a heat exchanger, a mixer, and a high-frequency induction heating coil connected to its oil inlet pipeline. The heat exchanger is used to heat the mixture of oil, water, and demulsifier. The mixer is located downstream of the heat exchanger, and the high-frequency induction heating coil is located downstream of the mixer. The high-frequency induction heating coil is connected in series in the loop of the power control cabinet and the transformer to further assist in heating the mixture after it has been heated by the heat exchanger. In the series-connected desalting tanks, along the oil flow direction, the oil inlet pipeline of the first desalting tank is directly connected to the tank washing oil source, and the oil outlet pipeline of the preceding desalting tank is connected to the oil inlet pipeline of the following desalting tank. In the parallel state of the electric desalting tanks, the oil inlet pipelines of all the electric desalting tanks are directly connected to the washing tank oil source, and the oil outlet pipelines of all the electric desalting tanks are connected.

2. The electrical desalting and dewatering apparatus for cleaning the oil tank according to claim 1, characterized by, The electro-desalination tank includes a primary electro-desalination tank, a secondary electro-desalination tank, and a tertiary electro-desalination tank. The primary, secondary, and tertiary electro-desalination tanks are connected in series, or the primary and secondary electro-desalination tanks are connected in parallel and connected in series with the tertiary electro-desalination tank, or the primary, secondary, and tertiary electro-desalination tanks are connected in parallel.

3. The electrical desalting and dewatering apparatus for cleaning the oil tank according to claim 2, characterized in that, The oil supply pipeline includes a first oil supply pipeline, a second oil supply pipeline, and a third oil supply pipeline, which are respectively connected to the oil inlet of the first-stage electric desalination tank, the oil inlet of the second-stage electric desalination tank, and the oil inlet of the third-stage electric desalination tank. The external oil pipeline includes a first external oil pipeline, a second external oil pipeline, and a third external oil pipeline, which are respectively connected to the oil outlet of the first-stage electric desalting tank, the oil outlet of the second-stage electric desalting tank, and the oil outlet of the third-stage electric desalting tank. in: The first oil inlet pipeline is connected to the tank washing oil source, the first oil outlet pipeline is connected to the second oil inlet pipeline, and the second oil outlet pipeline is connected to the third oil inlet pipeline. Alternatively, the first oil inlet pipeline and the second oil inlet pipeline are both connected to the tank washing oil source, and the first external oil outlet pipeline and the second external oil outlet pipeline are both connected to the third oil inlet pipeline. Alternatively, the first oil inlet pipeline, the second oil inlet pipeline, and the third oil inlet pipeline are all connected to the tank washing oil source, and the first external oil outlet pipeline, the second external oil outlet pipeline, and the third external oil outlet pipeline are all connected to the next oil processing unit.

4. The tank cleaning, oil-electric desalination, and dehydration equipment according to claim 3, characterized in that, The return water pipeline includes a first return water pipeline, a second return water pipeline, and a third return water pipeline, which are respectively connected to the outlets of the primary electro-desalination tank, the secondary electro-desalination tank, and the tertiary electro-desalination tank, wherein: When the primary desalination tank, the secondary desalination tank, and the tertiary desalination tank are connected in series, the second return water pipeline is connected to the first oil inlet pipeline, the third return water pipeline is connected to the second oil inlet pipeline, and the first return water pipeline is connected to the sewage treatment equipment. When the primary desalination tank and the secondary desalination tank are connected in parallel and the tertiary desalination tank is connected in series, the third return water pipeline is connected to the first oil inlet pipeline and the second oil inlet pipeline, and the first return water pipeline and the second return water pipeline are both connected to the sewage treatment equipment. When the primary desalination tank, the secondary desalination tank, and the tertiary desalination tank are connected in parallel, the water storage tank is connected to the first oil inlet pipe, the second oil inlet pipe, and the third oil inlet pipe through the first water inlet pipe, the second water inlet pipe, and the third oil inlet pipe, respectively, and the second return water pipe, the third return water pipe, and the first return water pipe are all connected to the sewage treatment equipment.

5. The tank cleaning, oil-electric desalination, and dehydration equipment according to claim 1, characterized in that, Each of the electro-desalination tanks is provided with an electrode plate, which is vertically arranged, and the electrode plate electrically connected to the positive terminal of the power supply and the electrode plate electrically connected to the negative terminal of the power supply are arranged at intervals along the length of the electro-desalination tank.

6. The tank cleaning, oil-electric desalination, and dehydration equipment according to claim 2, characterized in that, A high-frequency AC pulse electric field is formed in the primary and secondary electro-desalination tanks, and a high-frequency AC / DC pulse electric field is formed in the tertiary electro-desalination tank.

7. The tank cleaning, oil-electric desalination, and dehydration equipment according to claim 1, characterized in that, Each of the aforementioned desalting tanks is equipped with a crude oil distributor at the bottom of its inner cavity, and the oil supply pipeline is connected to the crude oil distributor.

8. A method for desalting and dehydrating tank oil using an electrostatic method, characterized in that, Using the tank cleaning, oil-electric desalting, and dehydration equipment according to any one of claims 1-7, the method comprises: The processing efficiency is adjusted by controlling whether the electric desalting tanks are connected in series or in parallel according to the salt content and water content in the tank washing oil. The tank washing oil to be treated is mixed with the demulsifier in the demulsifier pipeline, so that the water storage tank is connected to the oil inlet of the corresponding electric desalting tank through the water injection pipeline, or the water outlet of the latter electric desalting tank is connected to the oil inlet of the former electric desalting tank through the return water pipeline. The mixture is heated sequentially by the heat exchanger, the mixer, and the high-frequency induction heating coil, and then injected into all the electric desalination tanks that are connected in series or in parallel. After being treated by a high-frequency AC pulse electric field, the saline wastewater settles to the bottom of the tank and is discharged to the wastewater treatment equipment.

9. The tank cleaning oil electro-desalination and dehydration method according to claim 8, characterized in that, The electrostatic desalination tank includes a primary electrostatic desalination tank, a secondary electrostatic desalination tank, and a tertiary electrostatic desalination tank; When the salt content and water content in the tank cleaning oil are higher than the first set amount, the primary electric desalting tank, the secondary electric desalting tank and the tertiary electric desalting tank are connected in series, so that the tank cleaning oil to be treated is mixed with demulsifier and water, and then heated in sequence by the heat exchanger, the mixer and the high-frequency induction heating coil, and then flows in sequence through the primary electric desalting tank, the secondary electric desalting tank and the tertiary electric desalting tank for treatment; When the salt content and water content in the tank cleaning oil are higher than the second set amount but lower than the first set amount, the first-stage electric desalting tank and the second-stage electric desalting tank are connected in parallel and connected in series with the third-stage electric desalting tank. The tank cleaning oil to be treated is mixed with demulsifier and water, and then heated sequentially through the heat exchanger, the mixer, and the high-frequency induction heating coil. After flowing through the first-stage electric desalting tank and the second-stage electric desalting tank, it flows into the third-stage electric desalting tank for treatment. The second set amount is lower than the first set amount. When the salt content and water content in the tank cleaning oil are less than the second set amount, the primary electric desalting tank, the secondary electric desalting tank, and the tertiary electric desalting tank are connected in parallel. The tank cleaning oil to be treated is mixed with demulsifier and water, and then heated sequentially by the heat exchanger, the mixer, and the high-frequency induction heating coil before flowing through the parallel primary electric desalting tank, the secondary electric desalting tank, and the tertiary electric desalting tank for processing.

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