Petroleum coke special for prebaked anode and preparation method of petroleum coke

Abstract

The invention belongs to the technical field of petrochemical engineering, and particularly relates to petroleum coke special for a prebaked anode produced by taking high-sulfur high-acid crude oil as a raw material and a preparation method of the petroleum coke. According to the preparation method of the special petroleum coke for the prebaked anode, high-sulfur and high-metal crude oil is taken as a raw material, vacuum residue is prepared through reduced pressure distillation, then the high-sulfur and high-metal vacuum residue is treated by using a demetallization agent, and then the vacuum residue is subjected to mild hydrotreatment, so that a petroleum coke product with low metal content and sulfur content can be finally obtained. According to the preparation method of the special petroleum coke for the prebaked anode, the special petroleum coke for the high-end prebaked anode can be produced by utilizing inferior crude oil, so that the production raw material source of the petroleum coke is expanded, and the additional value of inferior ethylene tar is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and in particular relates to a prebaked anode-specific petroleum coke produced by taking high-sulfur and high-acid crude oil as raw material and a preparation method thereof. Background Art

[0002] Currently, the production process for prebaked anodes uses petroleum coke, a byproduct of oil refineries, as the aggregate (typically accounting for over 80% of the total mass of the prebaked anode), and coal tar, a byproduct of coking plants, as the binder. The coal tar is then bonded together to form a carbon block, which is then calcined to produce the prebaked anode. The cost of petroleum coke and coal tar accounts for approximately 75% of the production cost of the prebaked anode.

[0003] As the primary raw material for prebaked anodes, petroleum coke's product quality directly impacts the quality of the prebaked anodes. The main factors influencing petroleum coke quality are various trace elements. For example, trace elements such as Ni and V oxidize quickly, causing severe oxidation of the prebaked anodes and resulting in problems such as slagging and lumping. This reduces their conductivity and weakens the current effect within the aluminum electrolysis cell. This significantly increases the demand for carbon during the use of the prebaked anodes. Trace elements such as Si, Ti, Mn, and Fe primarily affect the mechanical properties and purity of the finished raw aluminum. Furthermore, elements such as S and P can reduce the quality and physical properties of carbon products. Therefore, these trace elements and the sulfur they contain in petroleum coke need to be processed and controlled to improve the quality of the prebaked anodes and reduce anode consumption. Furthermore, reducing the sulfur and metal content in petroleum coke can reduce the consumption of subsequent prebaked anodes prepared using petroleum coke as raw material, thereby reducing carbon dioxide emissions.

[0004] Currently, petroleum coke is generally produced from residual oil, a heavy oil obtained through vacuum distillation of crude oil. Residual oil is widely available. Generally speaking, when the sulfur content of petroleum coke is relatively low, anode consumption decreases as the sulfur content increases. This is primarily because sulfur increases the coking rate of the asphalt and reduces the porosity of the asphalt coke. Furthermore, sulfur combines with metallic impurities, reducing their catalytic effect. However, excessive sulfur content increases the thermal brittleness of the carbon anode. Furthermore, since sulfur primarily transforms into a gaseous phase as oxides during electrolysis, this can severely impact the electrolysis environment and pose significant environmental pressures. Furthermore, it can also form an iron sulfide film on the anode rod, increasing voltage drop.

[0005] Therefore, when producing anode coke, raw materials with low asphaltene, sulfur, metal content, and relatively low saturates should be selected. Especially with the continuous development of the oil refining industry and the annual increase in crude oil processing capacity, the degree of heaviness and inferiority of crude oil has become increasingly serious, resulting in increasingly poor residual oil properties, manifested in increasing metal, carbon residue, asphaltene, sulfur, and nitrogen contents. This leads to the deterioration of the raw material properties for anode coke production, making it increasingly difficult to produce qualified anode coke products.

[0006] Studies have shown that high-sulfur, high-metal crude oil contains high levels of elements such as Ca, Na, Ni, and V, as well as sulfur. Therefore, the petroleum coke produced by preparing residual oil from this crude oil also contains high levels of elements such as Ca, Na, Ni, and V. As a result, when this type of petroleum coke is used to produce prebaked anodes, the quality of the prebaked anodes is easily unstable, and only low-end prebaked anode products can be produced. Therefore, it is necessary to treat trace elements such as Ca, Na, Ni, and sulfur in crude oil. However, part of the Ca and Na in crude oil exists in the form of water-soluble salts or slightly soluble salts, while the other part exists in the form of calcium petroleum acid salts. The electrical desalination process in refineries can generally remove most water-soluble salts and hydrophilic inorganic salt particles, but there is almost no removal effect on lipophilic inorganic calcium salt particles, calcium petroleum acid salts, and organic elements such as nickel and vanadium that exist in the oil phase. When these trace elements eventually enter the petroleum coke, the content of elements such as Ca, Na, Ni, and V in the petroleum coke will exceed the standard, thereby affecting the quality of the petroleum coke product. At the same time, the sulfur in the crude oil will also be mostly enriched in the petroleum coke during the vacuum distillation and coking reaction, which will also lead to a higher sulfur content in the petroleum coke.

[0007] Conventionally, crude oil demetallization generally adopts the method for adding demetallizing agent, as Chinese patent CN114540071A discloses a kind of demetallizing agent, the method and device of removing metal in crude oil, it adopts pyroantimonic acid and / or pyroantimonate, and phase-transfer agent to carry out crude oil removal, and this method has used phase-transfer agent to overcome the energy barrier between oil and water in the removal process.But generally used phase-transfer agent is in the polymer or amine ammonium salt of alcohols, and the adding of these materials may remain in the residual oil, can affect the devices such as subsequent catalytic cracking.Therefore, this area expects to develop a kind of take victory crude oil as raw material, produces the special petroleum coke that is applicable to prepare prebaked anode based on residual oil, has positive significance for the development and production of prebaked anode. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to provide a pre-baked anode special petroleum coke produced from high-sulfur and high-acid crude oil, which not only expands the raw material source of petroleum coke production, but also increases the added value of inferior ethylene tar;

[0009] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned prebaked anode-specific petroleum coke.

[0010] In order to solve the above technical problems, the present invention provides a method for preparing prebaked petroleum coke for anodes, comprising the following steps:

[0011] (1) preparing vacuum residue oil from high-sulfur and high-metal crude oil as a raw material, and using the prepared vacuum residue oil as a coking raw material to prepare petroleum coke;

[0012] (2) adding a demetallizing agent to the vacuum residue and mixing, collecting the reaction product, extracting and filtering, removing the product generated by the reaction of the demetallizing agent and the trace elements, and collecting the purified vacuum residue;

[0013] (3) subjecting the vacuum residue to hydrogenation treatment to obtain hydrogenated vacuum residue;

[0014] (4) subjecting the obtained hydrogenated vacuum residue to thermal cracking reaction to obtain coking dry gas, coking gasoline, coking diesel, coking gas oil and petroleum coke, respectively.

[0015] Specifically, the method for preparing the prebaked anode-specific petroleum coke comprises the step (1) of performing vacuum distillation on the high-sulfur and high-metal crude oil;

[0016] Preferably, the condition parameters of the reduced pressure distillation step include: cutting temperature 400-540°C, vacuum degree 30-50Pa;

[0017] Preferably, the properties of the high-sulfur and high-metal crude oil are as follows: sulfur content 2.0-3.5wt%, Ca content 40-60mg·kg -1 , Fe content 20-30 mg·kg -1 , Ni content 30-50 mg·kg -1 , Si content 2-5 mg·kg -1 , V content 10-15 mg·kg -1 ;

[0018] Preferably, the properties of the vacuum residue are as follows: sulfur content 3-4.5wt%, Ca content 60-80mg·kg -1 , Fe content 40-60 mg·kg -1 , Ni content 50-65 mg·kg -1 , Si content 3-8 mg·kg -1 , V content 20-35 mg·kg -1 .

[0019] Specifically, in the method for preparing the prebaked anode-specific petroleum coke, in the step (2), the demetallizing agent includes a chelating agent, and the demetallizing agent reacts with Ca and Na salts in the residual oil to form a water-soluble product;

[0020] Preferably, the demetallizing agent comprises oxalic acid and / or EDTA;

[0021] Preferably, the demetallizing agent comprises a mixture of oxalic acid and EDTA;

[0022] Preferably, the demetallizing agent comprises a mixture of oxalic acid and EDTA in a mass ratio of 1-3:1;

[0023] Preferably, the amount of the demetallizing agent added is 100-200 mg·kg -1 ;

[0024] Preferably, the reaction time of adding the demetallizing agent is 2-3 hours.

[0025] Specifically, in the method for preparing prebaked anode-specific petroleum coke, in step (2), the extraction step includes adding an extractant for extraction, wherein the extractant can react with the demetallizing agent and Ca and Na salts to generate water-soluble products and remove them, and then the vacuum residue is introduced into an inorganic membrane filter for filtration;

[0026] Preferably, the extractant comprises a polyol solvent;

[0027] Preferably, the extractant comprises ethylene glycol.

[0028] Specifically, the method for preparing prebaked anode-specific petroleum coke, in step (2), further comprises the step of preheating the vacuum residue to 60-80° C.;

[0029] Preferably, the filtering step includes filtering using an inorganic membrane filter.

[0030] As a feasible solution, the inorganic membrane filter is made of ceramic material and is coated with a hydrophilic layer on its inner surface. The pore size of the ceramic filter membrane is 50-100um, and the operating pressure is 1-1.5MPa. After the residual oil with the demetallizing agent is added for mixed reaction, it enters the interior of the inorganic membrane. The water-soluble product generated by the reaction of the salt in the residual oil with the demetallizing agent passes through the hydrophilic membrane on the surface of the inorganic membrane and seeps out from the outside of the inorganic membrane under the action of pressure, while the residual oil passes through the inside of the inorganic membrane. In this way, the Ca and Na salt substances in the residual oil are removed, and the residual oil only contains Ni and V trace elements.

[0031] As an practicable solution, the hydrophilic layer on the surface of the inorganic membrane is modified polytetrafluoroethylene, and the modified groups are amino, carboxyl or sulfonic acid groups obtained by hydrolysis and condensation or free radical polymerization on the polytetrafluoroethylene.

[0032] As a feasible solution, the physical structure of the inorganic membrane is that the surface pore size of the inner wall of the membrane is larger and the pore size becomes smaller as it approaches the outer wall of the membrane. This is conducive to separating salt droplets of different sizes extracted from the residual oil.

[0033] Specifically, in the preparation method of the prebaked anode-specific petroleum coke, in the step (3), the hydrogenation reaction conditions of the hydrogenation treatment step include: a reaction temperature of 250°C-350°C, a hydrogen partial pressure of 1MPa-5MPa, and a volume space velocity of 1h -1 -2h -1 , hydrogen-oil volume ratio 300-400:1.

[0034] Specifically, in the method for preparing the prebaked anode-specific petroleum coke, in the step (3), the hydrotreating step includes the step of sequentially contacting the vacuum residue with a hydroprotectant and a hydrofining agent;

[0035] Preferably, the hydrogenation protective agent comprises an alumina carrier and molybdenum and / or tungsten and nickel and / or cobalt supported on the alumina carrier; preferably, based on the total weight of the hydrogenation protective agent and calculated as oxides, the content of molybdenum and / or tungsten is 1-10wt%, and the content of nickel and / or cobalt is 0.5-3wt%;

[0036] Preferably, the hydrotreating catalyst contains a carrier and molybdenum and / or tungsten and nickel and / or cobalt supported on the carrier; preferably, based on the total weight of the catalyst and calculated as oxides, the content of molybdenum and / or tungsten is 8-20wt%, and the content of nickel and / or cobalt is 0.3-8wt%; preferably, the carrier is aluminum oxide and / or silicon oxide.

[0037] As an operative solution, the hydrogenation protectant is in the form of Raschig rings and contains an alumina carrier and molybdenum and / or tungsten, as well as nickel and / or cobalt, supported on the alumina carrier. The molybdenum and / or tungsten content, calculated as oxides, is 1-10% by weight, and the nickel and / or cobalt content is 0.5-3% by weight, based on the total weight of the hydrogenation protectant. The alumina is γ-alumina, and the pore volume of the hydrogenation protectant is not less than 0.50 ml / g, preferably not less than 0.60 ml / g. This hydrogenation protectant can protect the primary catalyst and extend the operating time of the hydroprocessing unit.

[0038] As an practicable scheme, the hydrotreating catalyst contains a carrier and molybdenum and / or tungsten, and nickel and / or cobalt supported on the carrier. Based on the total weight of the catalyst and calculated as oxides, the content of molybdenum and / or tungsten is 8-20wt%, and the content of nickel and / or cobalt is 0.3-8wt%. The carrier is aluminum oxide and optionally silicon oxide. The pore distribution of the carrier is such that the volume of pores with a diameter of 60 angstroms to 100 angstroms accounts for 75% to 98% of the total pore volume. The pore volume of the hydrotreating catalyst is not less than 0.40 ml / g.

[0039] Specifically, in the preparation method of the prebaked anode-specific petroleum coke, in the step (3), the hydrogenation step includes a step of performing hydrogenation based on a fixed-bed hydrogenation reactor; when the vacuum residue oil after metal removal is hydrogenated, the raw oil is pressurized by a pump and mixed with hydrogen and then enters a heating furnace, and after heating, enters a fixed-bed hydrogenation reactor and sequentially contacts with a hydrogenation protective agent and a hydrogenation refining agent; the hydrogenated oil is separated into gas and liquid by a high-pressure separator, and the liquid product exits the device, and the gas is compressed by a compressor and mixed with new hydrogen and then mixed with the raw oil.

[0040] Preferably, based on the total loading volume of the catalyst in the fixed bed reactor, the volume percentages of the hydrogenation protective agent and the hydrogenation refining agent are 2%-30% and 70%-98% respectively.

[0041] The method of the present invention adopts the above-mentioned mild hydrogenation conditions and hydrogenation catalyst to hydrogenate the vacuum residue in step (2), which can not only remove most of the sulfur in the residue, but also remove trace elements such as Ni and V in the residue. At the same time, since most of the Ca and Na in the residue have been removed in step (2), the influence of Ca and Na metals on the hydrogenation protective agent can be reduced, the service life of the hydrogenation protective agent can be extended, and the cost of the device can be reduced.

[0042] Specifically, in the method for preparing prebaked anode-specific petroleum coke, in step (4), the parameters of the thermal cracking reaction step include: a heating furnace outlet temperature of 420°C-530°C, a coke drum pressure of 0.2MPa-1MPa, and a circulation ratio of 0.5-1;

[0043] Preferably, the thermal cracking reaction step is carried out based on a delayed coking device. As is common knowledge in the technical field, a delayed coking device at least includes a heating furnace, two coke towers and a fractionating tower.

[0044] The present invention also discloses pre-baked petroleum coke for anodes prepared by the method;

[0045] Preferably, the yield of the petroleum coke (green coke) is greater than 45 wt% (accounting for the coking raw materials), and the density of the petroleum coke is 2.08-2.13 g / cm 3 The sulfur content of the petroleum coke is less than 0.5wt%, and the Ca content of the petroleum coke is less than 100mg·kg -1 , the Fe content of the petroleum coke is less than 100 mg·kg -1 The Na content of the petroleum coke is less than 50 mg kg -1 , the Ni content of the petroleum coke is less than 100 mg·kg -1 , the Si content of the petroleum coke is less than 30 mg·kg -1 The V content of the petroleum coke is less than 50 mg kg-1 .

[0046] The method for preparing prebaked anode-specific petroleum coke of the present invention uses high-sulfur, high-metal crude oil as a raw material, produces vacuum residue through vacuum distillation, then treats the high-sulfur, high-metal vacuum residue with a demetallizing agent to react organic Ca and Na salts in the vacuum residue to form water-soluble inorganic salts. The demetallized vacuum residue is then filtered with an inorganic filter membrane with a hydrophilic modified internal surface to remove most of the Ca and Na salts in the residue. The vacuum residue is then subjected to a mild hydrogenation treatment to remove most of the Ni, V, and S in the vacuum residue, while also extending the service life of the hydrogenation protective agent. Ultimately, a petroleum coke product with low metal and sulfur content is obtained. The method for preparing prebaked anode-specific petroleum coke of the present invention utilizes the combined treatment of the above processes to produce high-end prebaked anode-specific petroleum coke from low-quality crude oil, thereby expanding the raw material source for petroleum coke production and increasing the added value of low-quality ethylene tar.

[0047] The method for preparing petroleum coke for prebaked anodes disclosed by the present invention comprises the following steps: firstly treating high-sulfur and high-metal vacuum residue with a demetallizing agent, reacting organic Ca and Na salts in the vacuum residue to generate water-soluble inorganic salts, then adding inorganic alcohol to extract the inorganic salt precipitate formed by the reaction, filtering the demetallized vacuum residue with an inorganic filter membrane having a hydrophilic modified internal surface to remove most of the Ca and Na salts in the residue, then subjecting the vacuum residue to a mild hydrogenation treatment to remove most of the Ni, V and S in the vacuum residue, and finally using the treated vacuum residue as a coking raw material to prepare low-emission petroleum coke with low metal and sulfur contents, thereby meeting the use requirements of high-end prebaked anodes.

[0048] The method for preparing prebaked anode-specific petroleum coke of the present invention first removes most of the Na and Ca salts in the vacuum residue by means of a demetallizing agent and an inorganic filtration membrane treatment, and then performs a mitigation and reduction, thereby reducing the total metal content in the hydrogenation raw material, alleviating the impact of metal substances on the hydrogenation protective agent, extending the service life of the hydrogenation protective agent, and reducing the operating cost of the device.

[0049] In the preparation method of prebaked anode-specific petroleum coke of the present invention, the surface of the inorganic filter membrane is hydrophilically modified, and the pore size from the inner wall to the outer wall of the inorganic membrane gradually changes from large to small, which is conducive to removing salt-containing extracts of different droplet sizes.

[0050] The petroleum coke specially used for prebaked anodes described in the present invention has the advantages of high metal content, low sulfur content and low emissions, can meet the demand for use of high-end prebaked anodes, and effectively solves the problem that the traditional use of vacuum residue oil prepared from high-sulfur and high-metal crude oil to produce petroleum coke has problems such as high metal content, high sulfur content, high metal content, low strength, and a large amount of fine coke, and the obtained petroleum coke product can only be sold as ordinary petroleum coke, resulting in a waste of resources. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention.

[0052] In the following examples of the present invention, as an exemplary embodiment, the filtration step is performed using an inorganic membrane filter. As an exemplary embodiment, the inorganic membrane filter is made of ceramic, coated with a hydrophilic layer on its inner surface, and the ceramic filter membrane has a pore size of 50-100 μm. The operating pressure is 1-1.5 MPa. After the residual oil is mixed with the demetallizing agent and reacts, it enters the inorganic membrane. The salts in the residual oil react with the demetallizing agent to form a water-soluble product that permeates the hydrophilic membrane on the surface of the inorganic membrane and, under the action of pressure, seeps out of the inorganic membrane while the residual oil passes through the inorganic membrane. This removes Ca and Na salts from the residual oil, leaving only trace elements Ni and V in the residual oil.

[0053] As an exemplary embodiment, the hydrophilic layer on the surface of the inorganic membrane is modified polytetrafluoroethylene. As a feasible solution, the physical structure of the inorganic membrane is characterized by larger pores on the inner wall and smaller pores toward the outer wall. This facilitates the separation of salt droplets of varying sizes extracted from residual oil.

[0054] In the following examples of the present invention, as an exemplary embodiment, the hydroprocessing step is performed based on a fixed-bed hydrogenation reactor, that is, the vacuum residue is sequentially contacted with a hydroprocessing protective agent and a hydroprocessing refining agent to achieve hydroprocessing.

[0055] As an exemplary embodiment, the hydrogenation protectant is in the form of Raschig rings and contains a γ-alumina carrier and molybdenum, tungsten, nickel, and cobalt supported on the alumina carrier. Based on the total weight of the hydrogenation protectant, the molybdenum and tungsten content is 5 wt%, and the nickel and cobalt content is 2 wt%, respectively. The pore volume of the hydrogenation protectant is no less than 0.50 ml / g. This hydrogenation protectant can protect the main catalyst and extend the operating time of the hydroprocessing unit.

[0056] As an exemplary embodiment, the hydrotreating catalyst contains an alumina carrier and molybdenum and tungsten, as well as nickel and cobalt supported on the carrier, with the content of molybdenum and tungsten being 15 wt% and the content of nickel and cobalt being 4 wt% based on the total weight of the catalyst and calculated as oxides; the pore distribution of the carrier is such that the volume of pores with a diameter of 60 angstroms to 100 angstroms accounts for 90% of the total pore volume, and the pore volume of the hydrotreating catalyst is not less than 0.40 ml / g.

[0057] As an exemplary embodiment, based on the total loading volume of the catalyst in the fixed bed reactor, the loading volume percentages of the hydrogenation protectant and the hydrogenation finishing agent are 20% and 85% respectively.

[0058] As an exemplary embodiment, the hydroprocessing step includes a step of performing hydroprocessing based on a fixed-bed hydroprocessing reactor; when the vacuum residue oil after metal removal is hydroprocessed, the raw oil is pressurized by a pump and mixed with hydrogen and then enters a heating furnace, and after heating, enters a fixed-bed hydroprocessing reactor, and sequentially contacts with a hydroprocessing protective agent and a hydroprocessing refining agent; the hydrogenated oil is separated into gas and liquid by a high-pressure separator, and the liquid product is discharged from the device, and the gas is compressed by a compressor, mixed with new hydrogen, and then mixed with the raw oil.

[0059] Example 1

[0060] In this example, high-sulfur and high-metal crude oil was used as raw material, and vacuum residue was prepared by vacuum distillation (controlling the cutting temperature at 480° C. and the vacuum degree at 40 Pa). The specific properties of the crude oil are shown in Table 1, and the properties of the obtained vacuum residue are shown in Table 2.

[0061] Table 1 Properties of high sulfur and high metal crude oil

[0062] Analysis Project Sulfur content, m% 2.0 <![CDATA[Ca,mg·kg -1 ]]> 40.2 <![CDATA[Ni,mg·kg -1 ]]> 30.3 <![CDATA[V,mg·kg -1 ]]> 10.6 <![CDATA[Fe,mg·kg -1 ]]> 20.5 <![CDATA[Si,mg·kg -1 ]]> 2.1

[0063] Table 2 Properties of high sulfur and high metal crude oil after vacuum distillation

[0064]

[0065]

[0066] After preheating the vacuum residue to 60°C, oxalic acid was added to the vacuum residue as a demetallizing agent in an amount of 100 mg kg -1 After mixing evenly for 2 hours, ethylene glycol is added as the polyol extract, and the vacuum residue oil is introduced into the inorganic membrane filter. The pore size of the ceramic filter membrane is selected to be 50μm, and the operating pressure is controlled to be 1MPa. The products generated by the reaction of the demetallizing agent and trace elements can be removed to obtain the purified vacuum residue oil.

[0067] The vacuum residue after metal removal was sent to a fixed bed hydrogenation reactor for hydrogenation treatment. The hydrogenation reaction conditions were controlled as follows: reaction temperature of 280°C, hydrogen partial pressure of 1.5 MPa, volume space velocity of 0.5 h -1 , hydrogen to oil volume ratio 500Nm 3 / m 3 , to obtain hydrogenated vacuum residue.

[0068] The hydrogenated vacuum residue is fed into a delayed coking unit for thermal cracking reaction. Parameters controlling the thermal cracking reaction step include: a heating furnace outlet temperature of 420°C, a coke drum pressure of 1 MPa, and a circulation ratio of 0.5. Coking dry gas, coking gasoline, coking diesel, coking gas oil, and petroleum coke can be obtained respectively.

[0069] The properties of the petroleum coke are shown in Table 3 below, indicating that high-sulfur and high-metal crude oil can be processed into high-quality petroleum coke products through a combined process of vacuum distillation-deacidification-hydrorefining-delayed coking.

[0070] Table 3 Petroleum coke product properties

[0071]

[0072] Example 2

[0073] In this example, high-sulfur, high-metal crude oil was used as raw material and vacuum residue was prepared by vacuum distillation (controlling the cutting temperature at 400° C. and the vacuum degree at 50 Pa). The specific properties of the crude oil are shown in Table 4, and the properties of the prepared vacuum residue are shown in Table 5.

[0074] Table 4 Properties of high sulfur and high metal crude oil

[0075] Analysis Project Sulfur content, m% 3.5 <![CDATA[Ca,mg·kg -1 ]]> 60.5 <![CDATA[Ni,mg·kg -1 ]]> 50.2 <![CDATA[V,mg·kg -1 ]]> 15.1 <![CDATA[Fe,mg·kg -1 ]]> 30.5 <![CDATA[Si,mg·kg -1 ]]> 5.7

[0076] Table 5 Properties of high sulfur and high metal crude oil after vacuum distillation

[0077] Analysis Project Sulfur content, m% 4.5 <![CDATA[Ca,mg·kg -1 ]]> 80.9 <![CDATA[Ni,mg·kg -1 ]]> 65.4 <![CDATA[V,mg·kg -1 ]]> 35.8 <![CDATA[Fe,mg·kg -1 ]]> 60.6 <![CDATA[Si,mg·kg -1 ]]> 8.8

[0078] After preheating the vacuum residue to 80°C, ethylene glycol was added as a polyol extract, and oxalic acid was added to the vacuum residue in an amount of 200 mg kg -1 After mixing evenly for 4 hours, the vacuum residue oil is introduced into the inorganic membrane filter. The pore size of the ceramic filter membrane is selected to be 100μm, and the operating pressure is 1.5MPa. The product generated by the reaction of the demetallizing agent and the trace elements is removed to obtain the purified vacuum residue oil.

[0079] The vacuum residue after metal removal was hydrogenated. The hydrogenation reaction conditions were: reaction temperature 300℃, hydrogen partial pressure 2MPa, volume space velocity 0.6h -1 , hydrogen oil volume ratio 550Nm3 / m 3 , to obtain hydrogenated vacuum residue.

[0080] The hydrogenated vacuum residue is fed into a delayed coking unit for thermal cracking reaction. Parameters controlling the thermal cracking reaction step include: a heating furnace outlet temperature of 530° C., a coke drum pressure of 0.2 MPa, and a circulation ratio of 1. Coking dry gas, coking gasoline, coking diesel, coking gas oil, and petroleum coke can be obtained respectively.

[0081] The properties of the obtained petroleum coke are shown in Table 6, indicating that high-sulfur and high-metal crude oil can be processed into high-quality petroleum coke products through a combined process of vacuum distillation-deacidification treatment-hydrorefining-delayed coking.

[0082] Table 6 Petroleum coke product properties

[0083]

[0084]

[0085] Example 3

[0086] In this example, high-sulfur, high-metal crude oil was used as raw material and vacuum distilled (controlling the cutting temperature at 540° C. and the vacuum degree at 30 Pa) to prepare vacuum residue. The specific properties of the crude oil are shown in Table 7, and the properties of the prepared vacuum residue are shown in Table 8.

[0087] Table 7 Properties of high sulfur and high metal crude oil

[0088] Analysis Project Sulfur content, m% 3.0 <![CDATA[Ca,mg·kg -1 ]]> 50.2 <![CDATA[Ni,mg·kg -1 ]]> 45.2 <![CDATA[V,mg·kg -1 ]]> 12.3 <![CDATA[Fe,mg·kg -1 ]]> 25.3 <![CDATA[Si,mg·kg -1 ]]> 3.5

[0089] Table 8 Properties of high sulfur and high metal crude oil after vacuum distillation

[0090] Analysis Project Sulfur content, m% 4.1 <![CDATA[Ca,mg·kg -1 ]]> 71.6 <![CDATA[Ni,mg·kg -1 ]]> 60.5 <![CDATA[V,mg·kg -1 ]]> 28.2 <![CDATA[Fe,mg·kg -1 ]]> 50.2 <![CDATA[Si,mg·kg -1 ]]> 5.2

[0091] After preheating the vacuum residue to 70°C, oxalic acid and EDTA (mass ratio 2:1) were added to the vacuum residue as demetallization agents. The addition amount was 150 mg kg -1 After mixing evenly for 3 hours, ethylene glycol is added as the polyol extract, and the vacuum residue oil is introduced into the inorganic membrane filter. The pore size of the ceramic filter membrane is selected to be 75μm, and the operating pressure is 1.2MPa. The product generated by the reaction of the demetallizing agent and the trace elements is removed to obtain the purified vacuum residue oil.

[0092] The vacuum residue after metal removal was hydrotreated. The hydrogenation reaction conditions were: reaction temperature 295 ° C, hydrogen partial pressure 1.7 MPa, volume space velocity 0.55 h -1 , hydrogen-to-oil volume ratio 530Nm 3 / m 3 , to obtain hydrogenated vacuum residue.

[0093] The hydrogenated vacuum residue is fed into a delayed coking unit for thermal cracking reaction. Parameters controlling the thermal cracking reaction step include: a heating furnace outlet temperature of 480° C., a coke drum pressure of 0.8 MPa, and a circulation ratio of 0.8. Coking dry gas, coking gasoline, coking diesel, coking gas oil, and petroleum coke can be obtained.

[0094] Among them, the properties of petroleum coke are shown in Table 9, which shows that high-sulfur and high-metal crude oil can be processed into high-quality petroleum coke products after vacuum distillation-deacidification treatment-hydrorefining-delayed coking combined process.

[0095] Table 9 Petroleum coke product properties

[0096]

[0097] Comparative Example 1

[0098] In this example, high-sulfur, high-metal crude oil was used as the raw material and vacuum residue was prepared by vacuum distillation (controlling the cutting temperature at 480° C. and the vacuum degree at 40 Pa). The specific properties of the crude oil are shown in Table 10, and the properties of the prepared vacuum residue are shown in Table 11.

[0099] Table 10 Properties of high sulfur and high metal crude oil

[0100] Analysis Project Sulfur content, m% 3.0 <![CDATA[Ca,mg·kg -1 ]]> 50.2 <![CDATA[Ni,mg·kg -1 ]]> 45.2 <![CDATA[V,mg·kg -1 ]]> 12.3 <![CDATA[Fe,mg·kg -1 ]]> 25.3 <![CDATA[Si,mg·kg -1 ]]> 3.5

[0101] Table 11 Properties of high sulfur and high metal crude oil after vacuum distillation

[0102] Analysis Project Sulfur content, m% 4.1 <![CDATA[Ca,mg·kg -1 ]]> 71.6 <![CDATA[Ni,mg·kg -1 ]]> 60.5 <![CDATA[V,mg·kg -1 ]]> 28.2 <![CDATA[Fe,mg·kg -1 ]]> 50.2 <![CDATA[Si,mg·kg -1 ]]> 5.2

[0103] The above vacuum residue oil was directly fed into the coking unit as raw material to produce petroleum coke. The properties of the obtained petroleum coke are shown in Table 12.

[0104] Table 12 Petroleum coke product properties

[0105]

[0106] Comparative Example 2

[0107] In this example, high-sulfur, high-metal crude oil was used as raw material and vacuum residue was prepared by vacuum distillation (controlling the cutting temperature at 480° C. and the vacuum degree at 40 Pa). The specific properties of the crude oil are shown in Table 13, and the properties of the prepared vacuum residue are shown in Table 14.

[0108] Table 13 Properties of high sulfur and high metal crude oil

[0109] Analysis Project Sulfur content, m% 3.0 <![CDATA[Ca,mg·kg -1 ]]> 50.2 <![CDATA[Ni,mg·kg -1 ]]> 45.2 <![CDATA[V,mg·kg -1 ]]> 12.3 <![CDATA[Fe,mg·kg -1 ]]> 25.3 <![CDATA[Si,mg·kg -1 ]]> 3.5

[0110] Table 14 Properties of high sulfur and high metal crude oil after vacuum distillation

[0111] Analysis Project Sulfur content, m% 4.1 <![CDATA[Ca,mg·kg -1 ]]> 71.6 <![CDATA[Ni,mg·kg -1 ]]> 60.5 <![CDATA[V,mg·kg -1 ]]> 28.2 <![CDATA[Fe,mg·kg -1 ]]> 50.2 <![CDATA[Si,mg·kg -1 ]]> 5.2

[0112] After preheating the vacuum residue to 70°C, oxalic acid and EDTA (mass ratio 2:1) were added to the vacuum residue as demetallization agents. The addition amount was 150 mg kg -1 After mixing evenly for 3 hours, ethylene glycol is added as the polyol extract, and the vacuum residue oil is introduced into the inorganic membrane filter. The pore size of the ceramic filter membrane is selected to be 75μm, and the operating pressure is 1.2MPa. The product generated by the reaction of the demetallizing agent and the trace elements is removed to obtain the purified vacuum residue oil.

[0113] The vacuum residue obtained is then directly fed into the coking unit to produce petroleum coke without undergoing hydrogenation treatment. The properties of the obtained petroleum coke are shown in Table 15.

[0114] Table 15 Petroleum coke product properties

[0115]

[0116] It can be seen from Comparative Examples 1 and 2 that the petroleum coke prepared by directly feeding the residual oil obtained from the high-sulfur and high-metal element crude oil into the coking unit without undergoing demetallization and hydrogenation treatment has high contents of various metal elements. However, the petroleum coke prepared by directly feeding the residual oil obtained from the crude oil into the coking unit without undergoing hydrogenation treatment still has high contents of metal elements such as Na, V, and Ni.

[0117] As can be seen, the method for preparing prebaked anode-specific petroleum coke of the present invention uses high-sulfur, high-metal crude oil as raw material, prepares vacuum residue through vacuum distillation, then treats the high-sulfur, high-metal vacuum residue with a demetallizing agent to react organic Ca and Na salts in the vacuum residue to form water-soluble inorganic salts, then filters the demetallized vacuum residue with an inorganic filter membrane with a hydrophilic modified internal surface to remove most of the Ca and Na salts in the residue, and then performs a mild hydrogenation treatment on the vacuum residue to remove most of the Ni, V, and S in the vacuum residue, while also extending the service life of the hydrogenation protective agent, ultimately obtaining a petroleum coke product with low metal and sulfur content. The method for preparing prebaked anode-specific petroleum coke of the present invention utilizes the combined treatment of the above processes to produce high-end prebaked anode-specific petroleum coke from low-quality crude oil, thereby expanding the source of raw materials for petroleum coke production and increasing the added value of low-quality ethylene tar.

[0118] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing prebaked petroleum coke for anode, characterized in that: The steps include: (1) Using high-sulfur and high-metal crude oil as raw material to prepare vacuum residue oil; (2) adding a demetallizing agent to the vacuum residue and mixing, collecting the reaction product, extracting and filtering, and collecting the purified vacuum residue; (3) subjecting the vacuum residue to hydrogenation treatment to obtain hydrogenated vacuum residue; (4) subjecting the obtained hydrogenated vacuum residue to thermal cracking reaction to obtain.

2. The method for preparing prebaked petroleum coke for anode according to claim 1, characterized in that: The step (1) includes the step of performing vacuum distillation on the high-sulfur and high-metal crude oil; Preferably, the condition parameters of the reduced pressure distillation step include: cutting temperature 400-540°C, vacuum degree 30-50Pa; Preferably, the property parameters of the high-sulfur and high-metal crude oil are as follows: sulfur content 2.0-3.5wt%, Ca content 40-60mg·kg -1 , Fe content 20-30 mg kg -1 , Ni content 30-50mg·kg -1 , Si content 2-5 mg·kg -1 , V content 10-15 mg kg -1 ; Preferably, the properties of the vacuum residue are as follows: sulfur content 3-4.5wt%, Ca content 60-80mg·kg -1 , Fe content 40-60 mg kg -1 , Ni content 50-65 mg kg -1 , Si content 3-8 mg kg -1 , V content 20-35 mg kg -1 .

3. The method for preparing prebaked petroleum coke for anode according to claim 1 or 2, characterized in that: In the step (2), the demetallizing agent comprises a chelating agent; Preferably, the demetallizing agent comprises oxalic acid and / or EDTA; Preferably, the demetallizing agent comprises a mixture of oxalic acid and EDTA; Preferably, the demetallizing agent comprises a mixture of oxalic acid and EDTA in a mass ratio of 1-3:1; Preferably, the amount of the demetallizing agent added is 100-200 mg·kg -1 .

4. The method for preparing prebaked petroleum coke for anode according to claim 3, characterized in that: In the step (2), the extraction step includes the step of adding an extractant for extraction; Preferably, the extractant comprises a polyol solvent; Preferably, the extractant comprises ethylene glycol.

5. The method for preparing prebaked petroleum coke for anode according to claim 3 or 4, characterized in that: The step (2) further includes preheating the vacuum residue to 60-80° C. Preferably, the filtering step includes the step of filtering with an inorganic membrane filter.

6. The method for preparing prebaked petroleum coke for anode according to any one of claims 1 to 5, characterized in that: In step (3), the hydrogenation reaction conditions of the hydrogenation step include: reaction temperature of 250°C-350°C, hydrogen partial pressure of 1MPa-5MPa, volume space velocity of 1h -1 -2h -1 , hydrogen-oil volume ratio 300-400:

1.

7. The method for preparing prebaked petroleum coke for anode according to claim 6, characterized in that: In the step (3), the hydroprocessing step includes the step of contacting the vacuum residue oil with a hydroprotectant and a hydrofining agent in sequence; Preferably, the hydrogenation protective agent contains an alumina carrier and molybdenum and / or tungsten and nickel and / or cobalt supported on the alumina carrier; preferably, based on the total weight of the hydrogenation protective agent and calculated as oxides, the content of the molybdenum and / or tungsten is 1-10wt%, and the content of the nickel and / or cobalt is 0.5-3wt%; Preferably, the hydrotreating catalyst contains a carrier and molybdenum and / or tungsten and nickel and / or cobalt loaded on the carrier; preferably, based on the total weight of the catalyst and calculated as oxides, the content of molybdenum and / or tungsten is 8-20wt%, and the content of nickel and / or cobalt is 0.3-8wt%; preferably, the carrier is aluminum oxide and / or silicon oxide.

8. The method for preparing prebaked petroleum coke for anode according to claim 6 or 7, characterized in that: In the step (3), the hydroprocessing step includes a step of performing hydroprocessing based on a fixed bed hydrogenation reactor; Preferably, based on the total loading volume of the catalyst in the fixed bed reactor, the loading volume percentages of the hydrogenation protective agent and the hydrogenation refining agent are 2%-30% and 70%-98% respectively.

9. The method for preparing prebaked petroleum coke for anode according to any one of claims 1 to 8, characterized in that: In step (4), the parameters of the thermal cracking reaction step include: heating furnace outlet temperature 420°C-530°C, coke drum pressure 0.2MPa-1MPa, circulation ratio 0.5-1; Preferably, the thermal cracking reaction step is carried out based on a delayed coking unit.

10. A prebaked petroleum coke for anode prepared by the method according to any one of claims 1 to 9; Preferably, the yield of the petroleum coke (green coke) is greater than 45wt% (accounting for the coking raw materials), and the density of the petroleum coke is 2.08-2.13g / cm 3 The sulfur content of the petroleum coke is less than 0.5wt%, and the Ca content of the petroleum coke is less than 100mg·kg -1 , the Fe content of the petroleum coke is less than 100 mg kg -1 , the Na content of the petroleum coke is less than 50 mg·kg -1 The Ni content of the petroleum coke is less than 100 mg kg -1 , the Si content of the petroleum coke is less than 30 mg·kg -1 , the V content of the petroleum coke is less than 50 mg·kg -1 .

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