Residual oil and preparation method thereof, petroleum coke and preparation method and application thereof

Abstract

The invention relates to the technical field of Shengli crude oil decalcifying agents, in particular to residual oil and a preparation method thereof, petroleum coke and a preparation method and application thereof, and the preparation method comprises the following steps: adding an emulsion containing a decalcifying agent and a glue retaining agent into crude oil, mixing, then carrying out electro-desalting treatment, and finally carrying out light component removal treatment to obtain the residual oil; wherein the particle size of liquid drops in the emulsion is 5-10 microns. The specific emulsion decalcifying agent liquid drops have good retaining ability, are not easily damaged by ultrasonic waves, can be fully and uniformly dispersed in crude oil, have a large contact area with an oil phase, and have a good decalcifying effect.

Description

Technical Field

[0001] The invention belongs to the technical field of residual oil preparation, and in particular relates to residual oil and a preparation method thereof, petroleum coke and a preparation method and application thereof. Background Art

[0002] Shengli crude oil is a high-sulfur and high-acid crude oil, and it also contains high levels of Ca and Na. Therefore, the petroleum coke produced by preparing residual oil from high-sulfur and high-acid crude oil contains high levels of Ca, Na and other elements, which makes it easy for this type of petroleum coke to cause unstable quality of prebaked anodes when used to produce prebaked anodes, and can only produce low-end prebaked anode products. Therefore, it is necessary to process the elements Ca, Na and other elements in the crude oil, and part of the calcium in the crude oil exists in the form of water-soluble salts and slightly soluble salts, and the other part exists in the form of calcium petroleum acid. In the process of electrical desalting in the refinery, most water-soluble salts and hydrophilic inorganic calcium salt particles can generally be removed, but when the viscosity of the crude oil is high, there is almost no removal effect on the lipophilic inorganic calcium salt particles and calcium petroleum acid in the oil phase. After this part of the Ca element finally enters the petroleum coke, it will cause the Ca element content in the petroleum coke to exceed the standard, thereby affecting the quality of the petroleum coke product.

[0003] Crude oil is generally decalcified by adding a decalcifying agent. The process of removing organic calcium from the decalcifying agent is a heterogeneous reaction process, and the reaction steps are as follows: (1) calcium compounds in the oil phase diffuse to the oil-water interface; (2) the decalcifying agent reacts with organic calcium at the oil-water interface to form chelates or water-soluble calcium salts; (3) the formed chelates or water-soluble calcium salts diffuse from the oil-water interface to the water phase. However, the content of colloidal asphaltene in high-viscosity crude oil is high, and the existing decalcifying agent cannot be fully dispersed in the oil phase, which is not conducive to the reaction between the lipophilic inorganic calcium salt particles and petroleum calcium acid and the effective ingredients of the decalcifying agent, resulting in poor removal effect of the decalcifying agent on the lipophilic inorganic calcium salt particles and petroleum calcium acid in the oil phase.

[0004] CN114540071A discloses a demetallization agent, a method and a device for removing metals from crude oil, which uses pyroantimonic acid and / or pyroantimonate and a phase transfer agent to remove crude oil. The method uses a phase transfer agent to overcome the energy barrier between oil and water during the removal process, but the phase transfer agent generally used is an alcohol polymer or an amine ammonium salt, and the addition of these substances may remain in the residual oil, which will affect subsequent catalytic cracking and other devices. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem that crude oil decalcification is difficult and insufficient in the prior art, and the Ca content in the prepared residual oil is high, and to provide a residual oil and a preparation method thereof, petroleum coke and a preparation method and application thereof. The preparation method can obtain residual oil with a low content of trace elements such as Ca.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a method for preparing residual oil, which comprises: adding an emulsion containing a decalcifying agent and a gel retaining agent into crude oil for mixing, then performing an electrical desalting treatment, and finally performing a light component removal treatment to obtain residual oil; wherein the droplet particle size in the emulsion is 5-10um.

[0007] The second aspect of the present invention provides a residual oil prepared by the residual oil preparation method of the present invention.

[0008] A third aspect of the present invention provides a method for preparing petroleum coke, the method comprising subjecting the residual oil of the present invention to a coking reaction.

[0009] A fourth aspect of the present invention provides a petroleum coke prepared by the petroleum coke preparation method of the present invention.

[0010] The fifth aspect of the present invention provides the use of the petroleum coke described in the present invention in the preparation of prebaked anodes.

[0011] The present invention has at least the following beneficial effects:

[0012] (1) In the preparation method of the present invention, the emulsion containing the decalcifying agent and the gel retaining agent can be fully dispersed in the crude oil, so that the decalcifying agent can fully react with the calcium in the oil to form a chelate or a water-soluble calcium salt. At the same time, the water-soluble calcium salt formed by the reaction under the action of ultrasound can more fully enter the water phase, thereby removing the generated water-soluble calcium salt to the maximum extent;

[0013] (2) In the present invention, the specific emulsion decalcifying agent droplets of the present invention have good retention ability and are not easily destroyed by ultrasound. The decalcifying agent droplets can be fully and uniformly dispersed in the crude oil, have a large contact area with the oil phase, and have a good decalcification effect. DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] The first aspect of the present invention provides a method for preparing residual oil, which comprises: adding an emulsion containing a decalcifying agent and a gel retaining agent into crude oil for mixing, then performing an electric desalting treatment under ultrasound, and finally performing a light component removal treatment to obtain residual oil; wherein the droplet particle size in the emulsion is 5-10um.

[0016] In the present invention, the specific emulsion of the present invention can make the decalcifying agent diffuse to the oil-water interface, so that the decalcifying agent can fully react with the calcium in the crude oil to form a chelate or a water-soluble calcium salt. At the same time, the demulsification characteristics of ultrasound can be used to fully demulsify the water phase in the crude oil, so that the water-soluble calcium salt formed by the reaction can more fully enter the water phase, and the generated water-soluble calcium salt can be removed to the maximum extent. In addition, the retention capacity of the decalcifying agent droplets is enhanced under the action of the gel retaining agent, and it is not easy to be destroyed by ultrasound. In this way, the decalcifying agent droplets can be fully and uniformly dispersed in the crude oil, increase the contact area between the decalcifying agent and the oil phase, enhance the decalcification effect, and achieve excellent decalcification effect without using other phase transfer agents (alcohol polymers or amine ammonium salts), which not only reduces the cost of three agents, but also eliminates the influence of the three agents on subsequent production.

[0017] In the present invention, the particle size of droplets in the emulsion is obtained by testing with a particle size analyzer.

[0018] In the present invention, as long as the purpose of the present invention can be achieved, the amount of the emulsion is not particularly limited. According to a preferred embodiment of the present invention, the amount of the emulsion is 1-5wt% of the mass of the crude oil, for example, 1wt%, 2wt%, 3wt%, 4wt% or 5wt%.

[0019] According to a preferred embodiment of the present invention, the decalcifying agent is selected from the group consisting of COOH - and / or PO4 3- Acid or its acid salt.

[0020] According to a preferred embodiment of the present invention, the decalcifying agent is selected from at least one of acetic acid, oxalic acid, phosphoric acid and citric acid and their acid salts. The decalcifying agent in the aforementioned embodiment can be more fully dispersed in the oil phase.

[0021] According to a preferred embodiment of the present invention, the decalcifying agent is oxalic acid.

[0022] According to a preferred embodiment of the present invention, the gel retainer is selected from polyvinyl alcohol gel retainers and / or cellulose gel retainers.

[0023] According to a preferred embodiment of the present invention, the gel retaining agent is selected from at least one of polyvinyl alcohol, hydroxyethyl cellulose and methyl cellulose with a degree of alcoholysis of 78%-88%. The aforementioned embodiment enhances the retention capacity of the decalcifying agent droplets, making the droplets in the emulsion less likely to be destroyed by ultrasound, further increasing the deionization effect.

[0024] According to a particularly preferred embodiment of the present invention, the gel retaining agent is a composition of hydroxyethyl cellulose and polyvinyl alcohol with an alcoholysis degree of 78%.

[0025] In the present invention, as long as the purpose of the present invention can be achieved, the amount of hydroxyethyl cellulose and polyvinyl alcohol with a degree of alcoholysis of 78% is not particularly limited, and is preferably (0.5-2):1, for example, 0.5:1, 1:1, 1.5:1, 2:1.

[0026] According to a particularly preferred embodiment of the present invention, in the emulsion, the content of the decalcifying agent is 1-1.5 wt%, for example, 1 wt%, 1.2 wt% or 1.5 wt%.

[0027] According to a particularly preferred embodiment of the present invention, in the emulsion, the content of the gel retaining agent is 0.5-1 wt%, for example, 0.5 wt%, 0.7 wt% or 1 wt%.

[0028] In the present invention, the emulsion containing the decalcifying agent and the gel retaining agent refers to an emulsion in which the decalcifying agent, the gel retaining agent and water are mixed. As long as the purpose of the present invention can be achieved, the preparation method of the emulsion is not particularly limited. For example, the decalcifying agent, the surfactant and water are sheared and mixed using a high-speed shearing machine. Specifically, the decalcifying agent and the surfactant are added to water together, and then high-speed shearing is performed using a high-speed shearing machine; preferably, the shear rate is 5000-7000rpm, the preferred shearing time is 3-8min, and the preferred shearing temperature is 20-30°C.

[0029] According to a preferred embodiment of the present invention, the temperature of the crude oil is 60-80° C. In the present invention, the crude oil can be preheated to 60-80° C. by conventional preheating methods.

[0030] According to a preferred embodiment of the present invention, the density of the crude oil at 25°C is 0.934-0.942 g·cm -3 .

[0031] According to a preferred embodiment of the present invention, the crude oil has a Ca content of 20.67-25.02 mg·kg -1 .

[0032] According to a preferred embodiment of the present invention, the crude oil has a Na content of 26.56-31.15 mg·kg -1 .

[0033] According to a preferred embodiment of the present invention, the sulfur content in the crude oil is 1.51-1.72wt%.

[0034] In the present invention, the method of the present invention can be used to process high-sulfur and high-acid crude oil. For example, Shengli crude oil is a high-sulfur and high-acid crude oil. At the same time, the crude oil contains relatively high contents of elements such as Ca and Na. The method of the present invention can significantly reduce the relatively high contents of elements such as Ca and Na in the crude oil.

[0035] According to a preferred embodiment of the present invention, the conditions of the electrical desalting treatment include: current 40-60mA. Using the above embodiment, under the current, voltage and ultrasonic conditions, when the crude oil is mixed with the emulsion, the small droplets in the emulsion can better convert the salt-containing water droplets in the oil into large droplets, and the emulsified water in the crude oil can be demulsified and removed to the maximum extent, so that the oil and the oil are separated, thereby better removing elements such as Ca and Na in the crude oil.

[0036] According to a preferred embodiment of the present invention, the conditions of the electrical desalting treatment include: the voltage is 200-300 V. Using the above embodiment, under the current, voltage and ultrasonic conditions, when the crude oil is mixed with the emulsion, the small droplets in the emulsion can better react with the salt-containing water droplets in the oil to become large droplets, and the emulsified water in the crude oil can be demulsified and removed to the maximum extent, so that the oil and the oil are separated, thereby better removing elements such as Ca and Na in the crude oil.

[0037] According to a preferred embodiment of the present invention, the ultrasonic condition includes: the ultrasonic power is 1000-2500 W. Using the above embodiment, under the current, voltage and ultrasonic conditions, when the crude oil is mixed with the emulsion, the small droplets in the emulsion can better convert the salt-containing water droplets in the oil into large droplets, and the emulsified water in the crude oil can be demulsified and removed to the maximum extent, so that the oil and the oil are separated, thereby better removing elements such as Ca and Na in the crude oil.

[0038] According to a preferred embodiment of the present invention, the ultrasonic conditions include: the ultrasonic time is 5-15 minutes. Using the above embodiment, under the current, voltage and ultrasonic conditions, when the crude oil is mixed with the emulsion, the small droplets in the emulsion can better convert the salt-containing water droplets in the oil into large droplets, and the emulsified water in the crude oil can be demulsified and removed to the maximum extent, so that the oil and the oil are separated, thereby better removing elements such as Ca and Na in the crude oil.

[0039] According to a preferred embodiment of the present invention, the Ca content in the treated crude oil is 1-8 mg·kg -1 , for example, 1 mg kg -1 , 1.5mg·kg -1 , 3.2mg·kg -1 , 4.2mg·kg -1 , 5mg·kg -1 , 6mg·kg -1 , 7mg·kg -1 or 8 mg kg -1 , preferably 1.5-5 mg·kg -1 .

[0040] In the present invention, crude oil contains light components such as gasoline, diesel and wax oil, and residual oil can be obtained after removing the light components. As long as the purpose of the present invention can be achieved, the method of removing the light components is not particularly limited, such as atmospheric and vacuum treatment, cutting and removing light components with an initial distillation point of (0°C) to 520°C, and then obtaining residual oil components. Specifically, the atmospheric vacuum degree is 13300kpa, and the reduced vacuum degree is 50kpa. Among them, gasoline cutting is generally carried out at 0-210°C, diesel cutting is carried out at 210-350°C, and wax oil cutting is carried out at 350-520°C. Removing light components is a conventional operating method, and no further elaboration is given in the present invention.

[0041] A second aspect of the present invention provides a residual oil, which is prepared by the residual oil preparation method of the present invention.

[0042] In the present invention, the content of each element in the residual oil prepared by the preparation method of the present invention can meet the requirements, and the residual oil can be used to prepare petroleum coke with excellent performance for high-end prebaked anodes.

[0043] According to a preferred embodiment of the present invention, the residual oil has a Ca content of <50 mg·kg -1 , preferably 10-40 mg·kg -1 , more preferably 10-35 mg·kg -1 .

[0044] According to a preferred embodiment of the present invention, the Fe content in the residual oil is less than 15 mg·kg -1 , preferably 2-14 mg·kg -1 , more preferably 2-10 mg·kg -1 .

[0045] According to a preferred embodiment of the present invention, the Na content in the residual oil is less than 4 mg·kg -1 , preferably 1-2 mg·kg -1 .

[0046] According to a preferred embodiment of the present invention, the Ni content in the residual oil is less than 60 mg·kg -1 , preferably 40-50 mg·kg -1 , more preferably 40-42 mg·kg -1 .

[0047] According to a preferred embodiment of the present invention, the Si content in the residual oil is less than 2 mg·kg -1 , preferably 1.5-2 mg·kg -1 .

[0048] According to a preferred embodiment of the present invention, the V content in the residual oil is less than 15 mg·kg -1 , preferably 10-14 mg·kg -1 , more preferably 10-12 mg·kg -1 .

[0049] A third aspect of the present invention provides a method for preparing petroleum coke, which comprises subjecting the residual oil of the present invention to a coking reaction.

[0050] In the present invention, the residual oil of the present invention is used for coking reaction to obtain special petroleum coke that meets the requirements of high-end prebaked anodes.

[0051] The device for carrying out the coking reaction in the present invention is not particularly limited, and can be a conventional coke tower in the art.

[0052] According to the present invention, as long as the purpose of the present invention can be achieved, the conditions of the coking reaction are not particularly limited, and can ensure normal coking. According to a preferred embodiment of the present invention, the conditions of the coking reaction include: a temperature of 490-495°C, and / or an operating pressure of 0.1-0.3Mpa. In the present invention, the temperature required for the coking reaction can be controlled by the outlet temperature of the heating furnace, and the operating pressure is the operating pressure of the coke drum. Under this temperature and operating pressure, normal coking can be achieved, and petroleum coke with qualified performance can be produced.

[0053] According to a preferred embodiment of the present invention, the preparation method further comprises decoking and coke washing after the coking reaction.

[0054] According to the present invention, decoking refers to stripping the solid material obtained by the coking reaction from the coke tower. According to a preferred embodiment of the present invention, the decoking method includes using water to wash the solid material obtained by coking; specifically, using high-pressure water washing to strip the solid material obtained by the coking reaction from the coke tower. This method is a conventional method in the art and the present invention will not elaborate on it.

[0055] According to the present invention, the water after decoking is called decoking water. According to a preferred embodiment of the present invention, the Ca content in the decoking water after decoking is less than 30 mg kg -1 .

[0056] According to a preferred embodiment of the present invention, the Na content in the decoking water after decoking is less than 20 mg kg -1 .

[0057] According to the present invention, coke washing refers to washing the solid material obtained by decoking with water to remove powder and other impurities therein. According to a preferred embodiment of the present invention, the coke washing method includes washing the solid material obtained by decoking with water. Coke washing is a conventional method in the art, and the present invention will not elaborate on it in detail.

[0058] According to the present invention, the water after the coke washing treatment is called coke washing water. According to a preferred embodiment of the present invention, the Ca content in the coke washing water after the coke washing treatment is less than 30 mg·kg -1 .

[0059] According to a preferred embodiment of the present invention, the Na content in the coke washing water after coke washing is less than 20 mg kg -1 .

[0060] A fourth aspect of the present invention provides a petroleum tar, which is prepared by the petroleum tar preparation method of the present invention.

[0061] In the present invention, when the petroleum tar prepared by the petroleum tar preparation method of the present invention is used to produce prebaked anodes, high-end prebaked anode products with unstable quality can be obtained.

[0062] According to a preferred embodiment of the present invention, the petroleum coke has a Ca content of <300 mg·kg -1 , preferably 200-298 mg·kg -1 , more preferably 200-280 mg·kg -1 .

[0063] According to a preferred embodiment of the present invention, the petroleum coke contains: Fe content < 200 mg·kg -1 , preferably 85-180 mg·kg -1 , more preferably 85-105 mg·kg -1 .

[0064] According to a preferred embodiment of the present invention, the petroleum coke has a Na content of <100 mg·kg -1 , preferably 60-95 mg·kg -1 , more preferably 60-90 mg·kg -1 .

[0065] According to a preferred embodiment of the present invention, the petroleum coke contains: Ni content < 200 mg·kg -1 , preferably 180-190 mg·kg -1 .

[0066] According to a preferred embodiment of the present invention, the petroleum coke contains: Si content < 200 mg·kg -1, preferably 30-70 mg·kg -1 , more preferably 35-50 mg·kg -1 .

[0067] According to a preferred embodiment of the present invention, the petroleum coke has a V content of <200 mg·kg -1 , preferably 60-100 mg·kg -1 , more preferably 75-90 mg·kg -1 .

[0068] A fifth aspect of the present invention provides the use of the petroleum coke of the present invention in the preparation of prebaked anodes.

[0069] In the present invention, when the petroleum tar of the present invention is used to produce prebaked anodes, high-end prebaked anode products with unstable quality can be obtained.

[0070] The present invention will be described in detail below through examples. In the following examples, the content of elements is measured by inductively coupled plasma chromatography (ICP) method.

[0071] Example 1

[0072] Residue oil is prepared from Shengli crude oil:

[0073] (1) The physical properties of crude oil are as follows: Ca content: 20.67 mg kg -1 、Na content: 26.56mg·kg -1 , sulfur content: 1.51wt%; the density of crude oil at 25℃ is 0.934g·cm -3 .

[0074] (2) After adding the decalcifying agent (oxalic acid, added in an amount of 1 wt%) and the surfactant (88% alcoholysis degree polyvinyl alcohol, added in an amount of 0.5 wt%) into deionized water, a high-speed shearing machine was used for high-speed shearing at a shear rate of 6000 rpm, a shearing time of 3 min, and a shearing temperature of 20° C., the droplet particle size in the formed emulsion was 5-8 μm.

[0075] (3) After the crude oil is preheated to 60°C, the obtained emulsion (the amount added is 3 wt% of the crude oil) is added to the crude oil and mixed thoroughly. After the mixing is completed, it enters the electric desalting tank for desalting treatment (current is 40 mA, voltage is 200 V). During the desalting process, ultrasonic waves are turned on to treat the crude oil synchronously. The ultrasonic power is 1500 W and the treatment time is 10 min. The Ca content in the treated crude oil is 5 mg kg -1 .

[0076] (4) The desalted crude oil is subjected to atmospheric and vacuum treatment (the atmospheric vacuum degree is 13300 kPa, the vacuum degree is 50 kPa, and the cutting temperature is from the initial distillation point to 520°C) to cut out the light components and obtain vacuum residue oil, wherein the content of each element in the residue oil is: Ca: 32 mg kg -1 , Fe: 9 mg kg -1 , Na: 2 mg kg -1 , Ni: 42 mg kg -1 , Si: 2 mg kg -1 , V: 12 mg kg -1 .

[0077] (5) The residual oil feedstock enters the coke tower for coking reaction. The outlet temperature of the heating furnace is 490°C and the operating pressure of the coke tower is 0.1 MPa. The generated ordinary petroleum coke remains in the coke tower. The petroleum coke is stripped from the coke tower by high-pressure water washing. The Ca content in the decoking water is 22 mg kg -1 , Na content is 15 mg kg -1 The stripped petroleum coke is then treated with coke washing water to remove the powder, etc. After coke washing, the Ca content in the coke washing water is 22 mg kg -1 , Na content is 15 mg kg -1 Finally, we obtained a special petroleum coke made of Shengli crude oil that meets the requirements of high-end pre-baked anodes. The content of each element in the petroleum coke is: Ca: 278 mg kg -1 , Fe: 103 mg kg -1 ,Na:86mg·kg -1 , Ni: 192 mg kg -1 , Si: 50 mg kg -1 , V: 89 mg kg -1 .

[0078] Example 2

[0079] Residue oil is prepared from Shengli crude oil:

[0080] (1) The physical properties of crude oil are as follows: Ca content: 25.02 mg kg -1 、Na content: 31.15mg·kg -1 , sulfur content: 1.72wt%, the density of crude oil at 25℃ is 0.939g·cm -3 .

[0081] (2) After adding the decalcifying agent (phosphoric acid, added in an amount of 1.5 wt%) and the surfactant (hydroxyethyl cellulose, added in an amount of 1 wt%) into deionized water, a high-speed shearing machine was used for high-speed shearing. The shear rate was 6000 rpm, the shear time was 5 min, the shear temperature was 30°C, and the droplet particle size in the formed emulsion was 5-8 um.

[0082] (3) After the crude oil is preheated to 80°C, the obtained emulsion (the amount added is 3 wt% of the crude oil) is added to the crude oil and mixed thoroughly. After the mixing is completed, the crude oil enters the electric desalting tank for desalting treatment (current is 60 mA, voltage is 300 V). During the desalting process, ultrasonic waves are turned on to treat the crude oil synchronously. The ultrasonic power is 2000 W and the treatment time is 5 min. The Ca content in the treated crude oil is 3 mg kg -1 .

[0083] (4) The desalted crude oil is subjected to atmospheric and vacuum treatment (the atmospheric vacuum degree is 13300 kPa, the reduced vacuum degree is 50 kPa, and the cutting temperature is from the initial distillation point to 520°C) to cut out the light components and obtain the residual oil, wherein the content of each element in the residual oil is: Ca: 25 mg·kg -1 , Fe: 6 mg kg -1 ,Na: 1.3mg·kg -1 , Ni: 42 mg kg -1 , Si: 2 mg kg -1 , V: 12 mg kg -1 .

[0084] (5) The residual oil feedstock enters the coke tower for coking reaction. The outlet temperature of the heating furnace is 495°C and the operating pressure of the coke tower is 0.3 MPa. The generated ordinary petroleum coke remains in the coke tower. The petroleum coke is stripped from the coke tower by high-pressure water washing. The Ca content in the decoking water is 20 mg kg -1 , Na content is 12 mg kg -1 The stripped petroleum coke was then treated with coke washing water. The Ca content in the coke washing water was 19 mg kg -1 , Na content is 11 mg kg -1 After removing the powder, we finally got the special petroleum coke which uses Shengli crude oil as raw material and meets the requirements of high-end pre-baked anode. The content of each element in the petroleum coke is: Ca: 251 mg kg -1 , Fe: 92 mg kg -1 ,Na: 67mg·kg -1 , Ni: 192 mg kg -1 , Si: 50 mg kg -1 , V: 89 mg kg -1 .

[0085] Example 3

[0086] Residue oil is prepared from Shengli crude oil:

[0087] (1) The physical properties of crude oil are as follows: Ca content: 22.19 mg kg -1 、Na content: 29.13 mg·kg -1 , sulfur content: 1.64wt%, the density of crude oil at 25℃ is 0.942g·cm -3 .

[0088] (2) After adding the decalcifying agent (citric acid, added in an amount of 1.2 wt%) and the surfactant (methyl cellulose, added in an amount of 0.7 wt%) into deionized water, a high-speed shearing machine was used for high-speed shearing. The shear rate was 6000 rpm, the shear time was 8 min, the shear temperature was 25°C, and the droplet particle size in the formed emulsion was 5-8 um.

[0089] (3) After the crude oil is preheated to 80°C, the obtained emulsion (the amount added is 3 wt% of the crude oil) is added to the crude oil and mixed thoroughly. After the mixing is completed, it enters the electric desalting tank for desalting treatment (current is 50 mA, voltage is 245 V). During the desalting process, ultrasonic waves are turned on to synchronously treat the crude oil. The ultrasonic power is 1700 W and the treatment time is 7 min. The Ca content in the treated crude oil is 4.2 mg kg -1 .

[0090] (4) After desalting Shengli crude oil, the content of each element in the vacuum residue is as follows: Ca: 27 mg kg -1 , Fe: 8 mg kg -1 ,Na: 1.6mg·kg -1 , Ni: 42 mg kg -1 , Si: 2 mg kg -1 , V: 12 mg kg -1 .

[0091] (5) The residual oil feedstock enters the coke tower for reaction. The outlet temperature of the heating furnace is 495°C and the operating pressure of the coke tower is 0.3 MPa. The generated ordinary petroleum coke remains in the coke tower. The petroleum coke is stripped from the coke tower by high-pressure water washing. The Ca content in the decoking water is 20 mg kg -1 , Na content is 12 mg kg -1The stripped petroleum coke is then treated with coke washing water to remove the powder, etc. After coke washing, the Ca content in the coke washing water is 19 mg kg -1 , Na content is 11 mg kg -1 After removing the powder, we finally got the special petroleum coke which uses Shengli crude oil as raw material and meets the requirements of high-end pre-baked anode. The content of each element in the petroleum coke is: Ca: 263mg·kg -1 , Fe: 102 mg kg -1 ,Na:75mg·kg -1 , Ni: 192 mg kg -1 , Si: 50 mg kg -1 , V: 89 mg kg -1 .

[0092] Example 4

[0093] Residue oil is prepared from Shengli crude oil:

[0094] (1) Shengli crude oil was fractionated to obtain vacuum residue oil. The properties of the crude oil are as follows: Ca content: 23.02 mg kg -1 、Na content: 30.12mg·kg -1 , sulfur content: 1.59wt%, the density of crude oil at 25℃ is 0.939g·cm -3 .

[0095] (2) After adding the decalcifying agent (acetic acid, added in an amount of 1.2 wt%) and the surfactant (hydroxycellulose, added in an amount of 0.6 wt%) into deionized water, a high-speed shearing machine was used for high-speed shearing. The shear rate was 6000 rpm, the shear time was 8 min, the shear temperature was 25°C, and the droplet particle size in the formed emulsion was 5-8 um.

[0096] (3) After the crude oil is preheated to 80°C, the obtained emulsion (the amount added is 3 wt% of the amount of crude oil added) is added to the crude oil and mixed thoroughly. After the mixing is completed, it enters the electric desalting tank for desalting treatment (current is 40 mA, voltage is 200 V). During the desalting process, ultrasonic waves are turned on to synchronously treat the crude oil. The ultrasonic power is 1800 W and the treatment time is 7 min. The Ca content in the treated crude oil is 3.2 mg kg -1 .

[0097] (4) After desalting Shengli crude oil, the content of each element in the vacuum residue is as follows: Ca: 22 mg kg -1 , Fe: 4.2 mg kg-1 , Na: 1.5 mg kg -1 , Ni: 42 mg kg -1 , Si: 2 mg kg -1 , V: 12 mg kg -1 .

[0098] (5) The residual oil feedstock enters the coke tower for reaction. The outlet temperature of the heating furnace is 495°C and the operating pressure of the coke tower is 0.3 MPa. The generated ordinary petroleum coke remains in the coke tower. The petroleum coke is stripped from the coke tower by high-pressure water washing. The Ca content in the decoking water is 20 mg kg -1 , Na content is 12 mg kg -1 The stripped petroleum coke is then treated with coke washing water to remove the powder, etc. After coke washing, the Ca content in the coke washing water is 19 mg kg -1 , Na content is 11 mg kg -1 After removing the powder, we finally got the special petroleum coke which uses Shengli crude oil as raw material and meets the requirements of high-end pre-baked anode. The content of each element in the petroleum coke is: Ca: 265mg·kg -1 , Fe: 103 mg kg -1 ,Na: 67mg·kg -1 , Ni: 192 mg kg -1 , Si: 50 mg kg -1 , V: 89 mg kg -1 .

[0099] Example 5

[0100] According to the method of Example 1, the difference is that

[0101] The adhesive retaining agent is a composition of polyvinyl alcohol with an alcoholysis degree of 78% and hydroxyethyl cellulose, and the mass ratio thereof is 1:1.

[0102] The Ca content in the treated crude oil is 1.5 mg kg -1 .

[0103] The content of each element in the obtained residual oil is: Ca: 11 mg kg -1 , Fe: 2.6 mg kg -1 ,Na: 1.1mg·kg -1 , Ni: 40 mg kg -1 , Si: 1.8 mg kg -1 , V: 11 mg kg -1 .

[0104] The content of each element in petroleum coke is: Ca: 212 mg kg -1, Fe: 85 mg kg -1 ,Na: 62mg·kg -1 , Ni: 184 mg kg -1 , Si: 36 mg kg -1 , V: 75 mg kg -1 .

[0105] Example 6

[0106] The method of Example 1 is followed, except that the power of ultrasound in step (3) is 2500 W and the treatment time is 15 min.

[0107] The Ca content in the treated crude oil is 6.8 mg kg -1 .

[0108] The content of each element in the obtained residual oil is: Ca: 37 mg kg -1 , Fe: 12 mg kg -1 , Na: 4 mg kg -1 , Ni: 44 mg kg -1 , Si: 5 mg kg -1 , V: 14 mg kg -1 .

[0109] The content of each element in petroleum coke is: Ca: 296 mg kg -1 , Fe: 119 mg kg -1 ,Na:96mg·kg -1 ,Ni:203mg·kg -1 , Si: 56 mg kg -1 , V: 93 mg kg -1 .

[0110] Example 7

[0111] The method of Example 1 is followed, except that the power of ultrasound in step (3) is 1400 W and the treatment time is 5 min.

[0112] The Ca content in the treated crude oil is 7.2 mg kg -1 .

[0113] The content of each element in the obtained residual oil is: Ca: 39 mg kg -1 , Fe: 14 mg kg -1 ,Na:6mg·kg -1 , Ni: 46 mg kg -1 , Si: 6 mg kg -1 , V: 15 mg kg -1 .

[0114] The content of each element in petroleum coke is: Ca: 301 mg kg -1 , Fe: 121 mg kg -1 ,Na:104mg·kg -1 , Ni: 204 mg kg -1 , Si: 67 mg kg -1 , V: 96 mg kg -1 .

[0115] Comparative Example 1

[0116] (1) Shengli crude oil is used as raw material. The physical properties of crude oil are as follows: Ca content: 20.67 mg kg -1 、Na content: 26.56mg·kg -1 , sulfur content: 1.51wt%, the density of crude oil at 25℃ is 0.937g·cm -3 .

[0117] (2) Deionized water (3 wt% of crude oil), 25 ppm of BP2040 demulsifier, 150 ppm of 8-hydroxyquinoline chelating agent and 40 ppm of quaternary ammonium salt were mixed with Shengli crude oil and subjected to an electric field of 1000 V at 60°C for 6 min. The crude oil and water were then separated and the Ca content in the crude oil was tested. The Ca content was 9 mg kg -1 .

[0118] Comparative Example 2

[0119] (1) Shengli crude oil is used as raw material. The physical properties of crude oil are as follows: Ca content: 20.67 mg kg -1 、Na content: 26.56mg·kg -1 , sulfur content: 1.51wt%, the density of crude oil at 25℃ is 0.939g·cm -3 .

[0120] (2) Deionized water (3 wt% of crude oil), 25 ppm of BP2040 demulsifier, 60 ppm of 4,8-dihydroxyquinoline chelating agent and 40 ppm of crown ether were mixed with Shengli crude oil and subjected to an electric field of 1000 V / cm at 60°C for 6 min. The crude oil and water were then separated and the Ca content in the crude oil was tested. The Ca content was 9 mg kg -1 .

[0121] Comparative Example 3

[0122] The method of Example 1 is followed, except that no gel retaining agent is added.

[0123] The Ca content in the treated crude oil is 9.3 mg kg -1 .

[0124] The content of each element in the obtained residual oil is: Ca: 46 mg kg -1 , Fe: 21 mg kg -1 ,Na:9mg·kg -1 , Ni: 49mg·kg -1 , Si: 8 mg kg -1 , V: 17 mg kg -1 .

[0125] The content of each element in petroleum coke is: Ca: 385 mg kg -1 , Fe: 167 mg kg -1 ,Na:135mg·kg -1 , Ni: 212 mg kg -1 , Si: 85 mg kg -1 , V: 116 mg kg -1 .

[0126] Comparative Example 4

[0127] The method of Example 1 is followed, except that the amount of the gel retainer added is 1.4 wt %, and the droplet particle size of the formed emulsion is 3-4 um.

[0128] The Ca content in the treated crude oil is 8.7 mg kg -1 .

[0129] The content of each element in the obtained residual oil is: Ca: 43 mg kg -1 , Fe: 19 mg kg -1 ,Na:8mg·kg -1 , Ni: 46 mg kg -1 , Si: 6 mg kg -1 , V: 15 mg kg -1 .

[0130] The content of each element in petroleum coke is: Ca: 365 mg kg -1 , Fe: 152 mg kg -1 ,Na:126mg·kg -1 , Ni: 206 mg kg -1 , Si: 78 mg kg -1 , V: 103 mg kg -1 .

[0131] Comparative Example 5

[0132] The method of Example 1 is followed, except that the amount of the gel retainer added is 0.3 wt % and the droplet particle size of the formed emulsion is 10-12 um.

[0133] The Ca content in the treated crude oil is 9.3 mg kg -1 .

[0134] The content of each element in the obtained residual oil is: Ca: 47 mg kg -1 , Fe: 22 mg kg -1 , Na: 10 mg kg -1 , Ni: 48 mg kg -1 , Si: 8 mg kg -1 , V: 17 mg kg -1 .

[0135] The content of each element in petroleum coke is: Ca: 378 mg kg -1 , Fe: 165 mg kg -1 ,Na:139mg·kg -1 , Ni: 213 mg kg -1 , Si: 87 mg kg -1 , V: 123 mg kg -1 .

[0136] Comparative Example 6

[0137] Residue oil is prepared from Shengli crude oil:

[0138] (1) The physical properties of crude oil are the same as those in Example 1.

[0139] (2) After the crude oil is preheated to 60°C, a decalcifying agent (oxalic acid, added in an amount of 1 wt% of deionized water), a surfactant (methyl cellulose, added in an amount of 1 wt% of deionized water) and deionized water (added in an amount of 3 wt% of the crude oil) are added to the crude oil and mixed thoroughly. After mixing, the crude oil enters an electric desalting tank for desalting treatment (current of 40 mA and voltage of 200 V). During the desalting process, ultrasonic waves are turned on to synchronously treat the crude oil. The ultrasonic power is 1500 W and the treatment time is 10 min. The Ca content in the treated crude oil is 9.8 mg kg -1 .

[0140] (3) The desalted crude oil is subjected to atmospheric and vacuum treatment (the atmospheric vacuum degree is 13300 kPa, the vacuum degree of the reduced pressure is 50 kPa, and the cutting temperature is from the initial distillation point to 520°C) to cut out the light components and obtain the residual oil, wherein the content of each element in the residual oil is: Ca: 49 mg·kg -1 , Fe: 25 mg kg -1,Na:12mg·kg -1 , Ni: 51 mg kg -1 , Si: 9 mg kg -1 , V: 19 mg kg -1 .

[0141] (4) The residual oil feedstock enters the coke tower for coking reaction. The outlet temperature of the heating furnace is 490°C and the operating pressure of the coke tower is 0.1 MPa. The generated ordinary petroleum coke remains in the coke tower. The petroleum coke is stripped from the coke tower by high-pressure water washing. The Ca content in the decoking water is 22 mg kg -1 , Na content is 15 mg kg -1 The peeled petroleum coke is then treated with water to remove the powder, etc. The Ca content in the coke washing water is 22 mg kg -1 , Na content is 15 mg kg -1 Finally, petroleum coke prepared from Shengli crude oil was obtained. The content of each element in the petroleum coke was: Ca: 386 mg kg -1 , Fe: 175 mg kg -1 ,Na:142mg·kg -1 , Ni: 221 mg kg -1 , Si: 91 mg kg -1 , V: 131 mg kg -1 .

[0142] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing residual oil, characterized in that: The preparation method comprises: An emulsion containing a decalcifying agent and a gel retaining agent is added to crude oil for mixing, and then subjected to an electrical desalting treatment under ultrasonic waves, and finally subjected to a light component removal treatment to obtain residual oil; wherein the droplet particle size in the emulsion is 5-10 um.

2. The method according to claim 1, wherein: The amount of the emulsion is 1-5wt% of the crude oil mass; and / or The decalcifying agent is selected from the group consisting of COOH - and / or PO4 3- Acid or its acid salt, preferably at least one selected from acetic acid, oxalic acid, phosphoric acid and citric acid and their acid salts, more preferably oxalic acid; and / or The gel retainer is selected from polyvinyl alcohol gel retainers and / or cellulose gel retainers, preferably at least one selected from polyvinyl alcohol with an alcoholysis degree of 78%-88%, hydroxyethyl cellulose and methyl cellulose, and more preferably a combination of hydroxyethyl cellulose and polyvinyl alcohol with an alcoholysis degree of 78%; and / or In the emulsion, the content of the decalcifying agent is 1-1.5wt%; and / or In the emulsion, the content of the gel retaining agent is 0.5-1wt%.

3. The method according to claim 1 or 2, wherein: The temperature of the crude oil is 60-80°C; and / or The density of the crude oil at 25°C is 0.934-0.942 g·cm -3 ; and / or In the crude oil: Ca content is 20.67-25.02 mg kg -1 ; and / or Na content: 26.56-31.15 mg kg -1 ; and / or The sulfur content is 1.51-1.72wt%.

4. The preparation method according to any one of claims 1 to 3, wherein The conditions of the electrical desalination treatment include: The current is 40-60mA; and / or Voltage is 200-300V; and / or The conditions for ultrasound include: Ultrasonic power of 1000-2500W; and / or The ultrasonic time is 5-15min.

5. A residual oil, characterized in that: The residual oil is prepared by the method described in any one of claims 1 to 4; Preferably, in the residual oil: Ca content<50mg·kg -1 ; and / or Fe content<15mg·kg -1 ; and / or Na content<4mg·kg -1 ; and / or Ni content<60mg·kg -1 ; and / or Si content<2mg·kg -1 ; and / or V content<15mg·kg -1 .

6. A method for preparing petroleum coke, characterized in that: The preparation method comprises: subjecting the residual oil according to claim 5 to a coking reaction.

7. The preparation method according to claim 6, wherein: The conditions of the coking reaction include: A temperature of 490-495°C; and / or The operating pressure is 0.1-0.3Mpa.

8. The preparation method according to claim 6 or 7, wherein: The preparation method also includes: After the coking reaction, decoking and coke washing are carried out; Preferably, The decoking method comprises: using water to wash the solid material obtained by the coking reaction, preferably the decoking water after decoking has a Ca content of less than 30 mg·kg -1 ; and / or Na content <20 mg kg -1 ; and / or The coke washing method comprises: washing the solid material obtained by decoking with water, preferably, the coke washing water after the coke washing has a Ca content of less than 30 mg·kg -1 ; and / or Na content <20 mg kg -1 .

9. A petroleum coke, characterized in that: The petroleum coke is prepared by the preparation method according to any one of claims 6 to 8; Preferably, in the petroleum coke: Ca content <300 mg kg -1 ; and / or Fe content <200 mg kg -1 ; and / or Na content <100 mg kg -1 ; and / or Ni content <200 mg kg -1 ; and / or Si content <200 mg kg -1 ; and / or V content <200 mg kg -1 .

10. Use of the petroleum coke according to claim 9 in preparing prebaked anodes.