Special petroleum coke for prebaked anode and preparation method thereof

Abstract

The application belongs to the technical field of petroleum chemical industry, and particularly relates to a special petroleum coke for prebaked anode produced by using high-sulfur and high-acid crude oil as raw material and a preparation method thereof. The preparation method of the special petroleum coke for prebaked anode disclosed by the application uses high-sulfur and high-metal crude oil as raw material, prepares vacuum residue through vacuum distillation, then uses a metal removal agent to treat the high-sulfur and high-metal vacuum residue, and then performs mild hydrogenation treatment on the vacuum residue, so that a petroleum coke product with low metal content and sulfur content can be finally obtained. The preparation method of the special petroleum coke for prebaked anode disclosed by the application can use inferior crude oil to produce high-end special petroleum coke for prebaked anode, which not only expands the production raw material source of the petroleum coke, but also improves the added value of inferior ethylene tar.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of petrochemical industry, and particularly relates to a special petroleum coke for pre-baked anode produced from high-sulfur and high-acid crude oil and a preparation method thereof. BACKGROUND

[0002] At present, the production process of the pre-baked anode is to use the by-product petroleum coke of the oil refinery as the aggregate (usually accounting for more than 80% of the total mass of the pre-baked anode), and then use the by-product coal tar pitch of the coking plant as the binder, form the carbon block after the pitch bonding, and then perform the baking treatment to obtain the pre-baked anode. Among them, the cost of the petroleum coke and the coal tar pitch accounts for about 75% of the production cost of the pre-baked anode.

[0003] The petroleum coke is the main production raw material of the pre-baked anode, and the product quality directly affects the quality of the pre-baked anode. The main factors affecting the quality of the petroleum coke are various trace elements, for example, the oxidation speed of the trace elements such as Ni and V is relatively fast, which causes the pre-baked anode to be seriously oxidized and appear problems such as slagging and chunking, resulting in the decrease of the electrical conductivity of the pre-baked anode, the weakening of the current effect in the aluminum electrolysis cell, and the significant increase of the demand for carbon during the use of the pre-baked anode; for another example, the trace elements such as Si, Ti, Mn and Fe mainly affect the mechanical properties and purity of the finished primary aluminum; for another example, the elements S and P will cause the decrease of the quality and physical properties of the carbon products. Therefore, it is necessary to treat and control these trace elements and the sulfur contained in the petroleum coke, so as to improve the quality of the pre-baked anode and the consumption of the anode; at the same time, the reduction of the sulfur and metal content in the petroleum coke can reduce the consumption of the pre-baked anode prepared by using the petroleum coke as the raw material in the subsequent process, and reduce the emission of carbon dioxide.

[0004] At present, the petroleum coke is generally prepared by using the residual oil, and the residual oil is the heavy residual oil obtained by the vacuum distillation of the crude oil, and its source is wide. Generally speaking, when the sulfur content of the petroleum coke is relatively low, the anode consumption decreases with the increase of the sulfur content, which is mainly because the sulfur improves the coking rate of the pitch and reduces the void fraction of the pitch coking; at the same time, the sulfur element also combines with the metal impurities, which reduces the catalytic effect of the metal impurities; however, if the sulfur content is too high, it will increase the thermal brittleness of the carbon anode, and since the sulfur is mainly converted into the gaseous phase in the form of oxide during the electrolysis process, it seriously affects the electrolysis environment, the environmental protection pressure is large, and in addition, it can also generate a thin film of iron sulfide on the anode rod, which increases the voltage drop.

[0005] Therefore, in the production of the anode coke raw material, the raw material with low pitch content, low sulfur content, low metal content and low saturated fraction content should be selected. Especially with the continuous development of the oil refining industry, the crude oil processing capacity is improved year by year, and the heavy and poor quality of the crude oil is becoming more and more serious, which makes the properties of the residual oil become worse and worse, and the properties of the raw material for producing the anode coke also become worse and worse, which makes it more and more difficult to produce qualified anode coke products.

[0006] Research shows that high-sulfur high-metal crude oil contains a high content of elements such as Ca, Na, Ni, V and sulfur content, therefore, the petroleum coke produced by the residual oil produced from such crude oil also contains a high content of elements such as Ca, Na, Ni, V, which causes the prebaked anode to be unstable in quality when used to produce prebaked anodes, and only low-end prebaked anode products can be produced. Therefore, the trace elements Ca, Na, Ni and sulfur in the crude oil need to be treated. However, part of the Ca and Na in the crude oil exists in the form of water-soluble salt and slightly soluble salt, and another part exists in the form of calcium petroleum acid. In the electric desalting process of the refinery, most of the water-soluble salt and hydrophilic inorganic salt particles can be removed, but the lipophilic inorganic calcium salt particles, calcium petroleum acid and organic nickel, vanadium and other elements existing in the oil phase have almost no removal effect. The trace elements in this part eventually enter the petroleum coke, which will cause the content of Ca, Na, Ni, V and other elements in the petroleum coke to 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 enriched in the petroleum coke during the vacuum distillation and coking reaction, so the sulfur content in the petroleum coke will be high.

[0007] Generally, crude oil demetallization generally adopts the method of adding a demetallizing agent, such as Chinese patent CN114540071A discloses a demetallizing agent, a method and device for removing metals from crude oil, which uses antimony pyrocatechuic acid and / or antimony pyrocatechuic acid salt, and a phase transfer agent to remove the crude oil. In the removal process, a phase transfer agent is used to overcome the energy barrier between oil and water. However, the commonly used phase transfer agent is a polymer of alcohol or an amine ammonium salt, and the addition of these substances may be left in the residual oil, which will affect the subsequent catalytic cracking device. Therefore, it is expected in the art to develop a special petroleum coke for producing prebaked anodes based on residual oil produced from Shengli crude oil, which has a positive significance for the development and production of prebaked anodes. SUMMARY

[0008] To this end, the technical problem to be solved by the present application is to provide a special petroleum coke for prebaked anodes produced from high-sulfur high-acid crude oil, which not only expands the production raw material source of petroleum coke, but also improves the added value of inferior ethylene tar.

[0009] The second technical problem to be solved by the present application is to provide a preparation method of the special petroleum coke for prebaked anodes.

[0010] To solve the above technical problems, the preparation method of the special petroleum coke for prebaked anodes provided by the present application comprises the following steps:

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

[0012] (2) adding a demetallization agent into the vacuum residue, mixing, collecting the reaction product, and removing the product generated by the reaction between the demetallization agent and trace elements through extraction and filtration to obtain purified vacuum residue;

[0013] (3) subjecting the vacuum residue to hydroprocessing to obtain hydroprocessed vacuum residue;

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

[0015] Specifically, in the step (1), the high-sulfur and high-metal crude oil is subjected to vacuum distillation.

[0016] Preferably, the condition parameters of the vacuum distillation step include a cutting temperature of 400-540°C and a vacuum degree of 30-50 Pa.

[0017] Preferably, the high-sulfur and high-metal crude oil has the following property parameters: a sulfur content of 2.0-3.5 wt%, a Ca content of 40-60 mg·kg -1 , a Fe content of 20-30 mg·kg -1 , a Ni content of 30-50 mg·kg -1 , a Si content of 2-5 mg·kg -1 , and a V content of 10-15 mg·kg -1 .

[0018] Preferably, the vacuum residue has the following property parameters: a sulfur content of 3-4.5 wt%, a Ca content of 60-80 mg·kg -1 , a Fe content of 40-60 mg·kg -1 , a Ni content of 50-65 mg·kg -1 , a Si content of 3-8 mg·kg -1 , and a V content of 20-35 mg·kg -1 .

[0019] Specifically, in the step (2), the demetallization agent includes a chelating agent, and the demetallization agent reacts with Ca and Na salts in the residue to form water-soluble products.

[0020] Preferably, the demetallization agent includes oxalic acid and / or EDTA.

[0021] Preferably, the demetallization agent includes 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 demetallizing agent is added in an amount of 100-200 mg·kg -1 ;

[0024] Preferably, the time for the demetallizing agent to react is 2-3 h.

[0025] Specifically, in the preparation method of the petroleum coke for special use in prebaked anodes, in the step (2), the extraction step comprises a step of adding an extractant to perform extraction, and 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 to perform filtration.

[0026] Preferably, the extractant comprises a polyhydric alcohol solvent.

[0027] Preferably, the extractant comprises ethylene glycol.

[0028] Specifically, in the preparation method of the petroleum coke for special use in prebaked anodes, in the step (2), the vacuum residue is further preheated to 60-80 ℃.

[0029] Preferably, the filtration step comprises a step of filtration performed by an inorganic membrane filter.

[0030] As an implementable scheme, the inorganic membrane filter is made of ceramic material, and a hydrophilic layer is plated on the inner surface of the inorganic membrane filter. The pore size of the ceramic filter membrane is 50-100 um, and the use pressure is 1-1.5 MPa. After the demetallizing agent is added into the vacuum residue to perform mixing reaction, the water-soluble products generated by the reaction of the salts in the vacuum residue and the demetallizing agent permeate through the hydrophilic layer on the surface of the inorganic membrane filter and seep out from the outside of the inorganic membrane filter under the action of pressure, while the vacuum residue passes through the inside of the inorganic membrane filter. In this way, the Ca and Na salts in the vacuum residue are removed, and only Ni and V trace elements are contained in the vacuum residue.

[0031] As an implementable scheme, the hydrophilic layer on the surface of the inorganic membrane filter is polytetrafluoroethylene after modification, and the modified groups are amino groups, carboxyl groups or sulfonic acid groups generated by hydrolytic condensation or radical polymerization on the polytetrafluoroethylene.

[0032] As an implementable scheme, the physical structure of the inorganic membrane filter is that the pore size of the surface of the inner wall of the membrane filter is large, and the pore size becomes smaller and smaller as the outer wall of the membrane filter is approached. This is beneficial to the separation of different sizes of salt-containing droplets extracted from the vacuum residue.

[0033] Specifically, the preparation method of the special petroleum coke for prebaked anode, in the step (3), the hydrogenation treatment step includes the step of contacting the vacuum residue with a hydrogenation guard agent and a hydrogenation refining agent in sequence. -1 -2h -1 , and the hydrogen-oil volume ratio is 300-400:1.

[0034] Specifically, the preparation method of the special petroleum coke for prebaked anode, in the step (3), the hydrogenation treatment step includes the step of contacting the vacuum residue with a hydrogenation guard agent and a hydrogenation refining agent in sequence.

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

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

[0037] As an implementable scheme, the hydrogenation guard agent is a Raschig ring, contains an alumina carrier and molybdenum and / or tungsten and nickel and / or cobalt supported on the alumina carrier, the content of the molybdenum and / or tungsten is 1 wt%-10 wt% and the content of the nickel and / or cobalt is 0.5-3 wt% based on the total weight of the hydrogenation guard agent and in terms of oxides; the alumina is γ-alumina, and the pore volume of the hydrogenation guard agent is not less than 0.50 ml / g, preferably not less than 0.60 ml / g. The use of the hydrogenation guard agent can protect the main catalyst and prolong the running time of the hydrogenation treatment device.

[0038] As an implementable scheme, the hydrogenation refining catalyst contains a carrier and molybdenum and / or tungsten and nickel and / or cobalt supported on the carrier, the content of the molybdenum and / or tungsten is 8-20 wt% and the content of the nickel and / or cobalt is 0.3-8 wt% based on the total weight of the catalyst and in terms of oxides, and the carrier is alumina and optionally silicon oxide; the pore distribution of the carrier is that the pore volume with a diameter of 60 angstroms-100 angstroms accounts for 75%-98% of the total pore volume, and the pore volume of the hydrogenation refining catalyst is not less than 0.40 ml / g.

[0039] Specifically, in the step (3), the hydrogenation treatment step comprises a step of hydrogenation treatment based on a fixed-bed hydrogenation reactor; when the vacuum residue after removal of metals is subjected to hydrogenation treatment, the raw oil pump is pressurized and mixed with hydrogen, and then enters a heating furnace, and after heating, enters the fixed-bed hydrogenation reactor, and is sequentially contacted with a hydrogenation guard agent and a hydrogenation refining agent; the hydrogenation product oil is subjected to gas-liquid separation 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.

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

[0041] The method can not only remove most of the sulfur in the residue oil, but also remove trace elements such as Ni and V in the residue oil. In addition, since most of the Ca and Na in the residue oil have been removed in step (2), the influence of Ca and Na metals on the hydrogenation guard agent can be reduced, the service life of the hydrogenation guard agent can be prolonged, and the cost of the device can be reduced.

[0042] Specifically, in the step (4), the parameters of the thermal cracking reaction step include: heating furnace outlet temperature 420-530℃, coke drum pressure 0.2-1MPa, and circulation ratio 0.5-1.

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

[0044] The application further discloses the petroleum coke for pre-baked anodes prepared by the method.

[0045] Preferably, the yield of the petroleum coke (green coke) is greater than 45wt% (based on the coking raw material), 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%, the Ca content of the petroleum coke is <100mg·kg -1 , the Fe content of the petroleum coke is <100mg·kg -1 , the Na content of the petroleum coke is <50mg·kg -1 , the Ni content of the petroleum coke is <100mg·kg -1 , the Si content of the petroleum coke is <30mg·kg -1 , and the V content of the petroleum coke is <50mg·kg-1 .

[0046] The preparation method of the special petroleum coke for prebaked anode disclosed in the application uses high-sulfur and high-metal crude oil as raw material, prepares vacuum residue through vacuum distillation, and then uses a demetallization agent to treat the high-sulfur and high-metal vacuum residue, so that the organic Ca and Na salts in the vacuum residue are reacted to form inorganic salts soluble in water, and then an inorganic filter membrane with a hydrophilic modified internal surface is used to filter the demetallized vacuum residue, so that most of the Ca and Na salts in the residue are removed, and then the vacuum residue is subjected to mild hydrogenation treatment to remove most of Ni, V and S in the vacuum residue, and at the same time, the service life of the hydrogenation protective agent is extended, and finally a petroleum coke product with low metal content and sulfur content can be obtained. The preparation method of the special petroleum coke for prebaked anode disclosed in the application uses the above-mentioned combined process to produce high-end special petroleum coke for prebaked anode from inferior crude oil, which not only expands the source of petroleum coke production raw materials, but also improves the added value of inferior ethylene tar.

[0047] The preparation method of the special petroleum coke for prebaked anode disclosed in the application first uses a demetallization agent to treat high-sulfur and high-metal vacuum residue, so that the organic Ca and Na salts in the vacuum residue are reacted to form inorganic salts soluble in water, and then inorganic alcohol is added to precipitate and extract the inorganic salts formed by the reaction, and then an inorganic filter membrane with a hydrophilic modified internal surface is used to filter the demetallized vacuum residue, so that most of the Ca and Na salts in the residue are removed, and then the vacuum residue is subjected to mild hydrogenation treatment to remove most of Ni, V and S in the vacuum residue, and the treated vacuum residue is used as a coking raw material to finally prepare low-emission petroleum coke with low metal content and sulfur content, which can meet the use requirements of high-end prebaked anode.

[0048] The preparation method of the special petroleum coke for prebaked anode disclosed in the application first removes most of the Na and Ca salts in the vacuum residue through the treatment of a demetallization agent and an inorganic filter membrane, and then performs mild hydrogenation, so that the total metal content in the hydrogenation raw material is reduced, the influence of metal substances on the hydrogenation protective agent is reduced, the service life of the hydrogenation protective agent is extended, and the operation cost of the device is reduced.

[0049] The preparation method of the special petroleum coke for prebaked anode disclosed in the application uses an inorganic filter membrane with a hydrophilically modified surface, and the pore size gradually changes from large to small from the inner wall to the outer wall of the inorganic membrane, which is beneficial to the removal of salt-containing extraction liquid with different droplet sizes.

[0050] The special petroleum coke for prebaked anode has the advantages of high metal content, low sulfur content and low emission, can meet the use demand of high-end prebaked anode, and effectively solves the problems that the petroleum coke product obtained by using the vacuum residue prepared from traditional high-sulfur high-metal crude oil to produce petroleum coke has high metal content, high sulfur content, high metal content, low strength, and high amount of powder coke, and can only be sold as ordinary petroleum coke, thereby causing resource waste. DETAILED DESCRIPTION

[0051] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application.

[0052] In the following embodiments of the present application, as an exemplary embodiment, the filtering step is a step of filtering by using an inorganic membrane filter. As an exemplary embodiment, the inorganic membrane filter is made of ceramic material, and has a hydrophilic layer plated on the inner surface thereof, and the pore size of the ceramic filter membrane is 50-100 μm. After the residue oil to which a demetallization agent is added is mixed and reacted, the residue oil enters the inside of the inorganic membrane, and the water-soluble product generated by the reaction of the salt in the residue oil and the demetallization agent permeates 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 residue oil passes through the inside of the inorganic membrane. In this way, the Ca and Na salt substances in the residue oil are removed, and only the Ni and V trace elements are contained in the residue oil.

[0053] As an exemplary embodiment, the hydrophilic layer on the surface of the inorganic membrane is polytetrafluoroethylene after modification. As an implementable solution, the physical structure of the inorganic membrane is that the pore size of the surface of the inner wall of the membrane is large, and the pore size of the outer wall of the membrane is small. This is beneficial to the separation of the salt-containing droplets of different sizes extracted from the residue oil.

[0054] In the following embodiments of the present application, as an exemplary embodiment, the hydroprocessing step is based on a fixed-bed hydrogenation reactor, that is, the vacuum residue is sequentially contacted with a hydrogenation preservative agent and a hydrogenation refining agent to realize hydroprocessing.

[0055] As an exemplary embodiment, the hydrogenation preservative agent is a lacunary ring, contains a gamma-alumina carrier and molybdenum and tungsten supported on the alumina carrier, and nickel and cobalt, and the content of molybdenum and tungsten is 5 wt% and the content of nickel and cobalt is 2 wt% respectively, based on the total weight of the hydrogenation preservative agent and in terms of oxides; the pore volume of the hydrogenation preservative agent is not less than 0.50 ml / g. The use of the hydrogenation preservative agent can protect the main catalyst and prolong the running time of the hydroprocessing device.

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

[0057] As an exemplary embodiment, the volume percentage of the hydroprotection agent and the hydrofining agent filled in the fixed bed reactor is 20% and 85% respectively based on the total filling volume of the catalyst in the fixed bed reactor.

[0058] As an exemplary embodiment, the hydroprocessing step includes the step of hydroprocessing based on a fixed bed hydrogenation reactor; when hydroprocessing the demetallized vacuum residue, the raw oil pump is pressurized and mixed with hydrogen, then enters a heating furnace, and after heating, enters the fixed bed hydrogenation reactor, and is sequentially contacted with the hydroprotection agent and the hydrofining agent; the hydroprocessed oil is subjected to gas-liquid separation in 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 mixed with the raw oil.

[0059] Example 1

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

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

[0062] Analysis item sulfur content, m% 2.0 Ca, mg kg -1 ]] 40.2 Ni, mg·kg -1 ]] 30.3 V, mg·kg -1 ]]> 10.6 Fe, mg kg -1 ]] 20.5 Si, mg kg -1 ]] 2.1

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

[0064]

[0065]

[0066] The obtained vacuum residue is preheated to 60°C, and oxalic acid is added as a demetallizing agent, the amount of which is 100 mg·kg -1 , and the mixture is uniformly mixed for 2 hours, then ethylene glycol is added as a polyhydric alcohol extraction liquid, and the vacuum residue is introduced into an inorganic membrane filter, the pore size of the ceramic filter membrane is selected to be 50 μm, and the operating pressure is controlled to be 1 MPa, so that the products generated by the reaction of the demetallizing agent and trace elements can be removed, and the purified vacuum residue is obtained.

[0067] The above-mentioned vacuum residue after removing metal is sent into a fixed bed hydrogenation reactor for hydrogenation treatment, and the hydrogenation reaction conditions are controlled as follows: the reaction temperature is 280℃, the hydrogen partial pressure is 1.5MPa, the volume space velocity is 0.5h -1 , and the hydrogen / oil volume ratio is 500Nm 3 / m 3 , to obtain hydrogenated vacuum residue.

[0068] The hydrogenated vacuum residue is input into a delayed coking device for thermal cracking reaction, and the parameters of the thermal cracking reaction step are controlled as follows: the heating furnace outlet temperature is 420℃, the coke tower pressure is 1MPa, and the circulation ratio is 0.5, to obtain coking dry gas, coking gasoline and coking diesel, coking gas oil and petroleum coke, respectively.

[0069] The properties of the petroleum coke are shown in Table 3, which shows that high-quality petroleum coke products can be prepared after the high-sulfur and high-metal crude oil is processed by the combined process of vacuum distillation-acid removal treatment-hydrogenation refining-delayed coking.

[0070] Table 3 Properties of petroleum coke products

[0071]

[0072] Example 2

[0073] In this example, high-sulfur and high-metal crude oil is used as raw material, and vacuum residue is prepared by vacuum distillation (the cutting temperature is controlled at 400℃, and the vacuum degree is 50Pa), wherein 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 item sulfur content, m% 3.5 Ca, mg kg -1 ]]> 60.5 Ni, mg·kg -1 ]]> 50.2 V, mg·kg -1 ]]> 15.1 Fe, mg kg -1 ]] 30.5 Si, mg kg -1 ]] 5.7

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

[0077] Analysis item sulfur content, m% 4.5 Ca, mg kg -1 ]] 80.9 Ni, mg·kg -1 ]]> 65.4 V, mg·kg -1 ]]> 35.8 Fe, mg kg -1 ]] 60.6 Si, mg kg -1 ]] 8.8

[0078] After the obtained vacuum residue is preheated to 80℃, glycol is added as a polyhydric alcohol extraction liquid, and oxalic acid is added to the vacuum residue, and the amount of addition is 200mg·kg -1 , and after being uniformly mixed for 4h, the vacuum residue is introduced into an inorganic membrane filter, the pore size of the ceramic filter membrane is selected to be 100μm, and the operating pressure is 1.5MPa, to remove the products generated by the reaction of the demetallizing agent and trace elements, to obtain purified vacuum residue.

[0079] The vacuum residue after removing metal is subjected to hydrogenation treatment, and the hydrogenation reaction conditions are as follows: the reaction temperature is 300℃, the hydrogen partial pressure is 2MPa, the volume space velocity is 0.6h -1 , and the hydrogen / oil volume ratio is 550Nm3 / m 3 , to obtain the hydro-reduced residue oil.

[0080] The hydro-reduced residue oil is input into a delayed coking device for thermal cracking reaction, and parameters of the thermal cracking reaction step are controlled to include: heating furnace outlet temperature 530℃, coke tower pressure 0.2MPa, and circulation ratio 1; coking dry gas, coking gasoline and coking diesel, coking gas oil and petroleum coke can be obtained respectively.

[0081] The properties of the petroleum coke obtained are shown in Table 6, indicating that high-quality petroleum coke products can be prepared after the high-sulfur and high-metal crude oil is processed by the combined process of vacuum distillation-acid removal treatment-hydrorefining-delayed coking.

[0082] Table 6 Properties of petroleum coke products

[0083]

[0084]

[0085] Example 3

[0086] In this example, a high-sulfur and high-metal crude oil is used as a raw material, and a vacuum residue is prepared by vacuum distillation (cutting temperature controlled at 540℃, vacuum degree 30Pa), wherein 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 item sulfur content, m% 3.0 Ca, mg-kg -1 ]] 50.2 Ni, mg·kg -1 ]]> 45.2 V, mg·kg -1 ]]> 12.3 Fe, mg kg -1 ]] 25.3 Si, mg kg -1 ]] 3.5

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

[0090] Analysis item sulfur content, m% 4.1 Ca, mg-kg -1 ]] 71.6 Ni, mg·kg -1 ]]> 60.5 V, mg·kg -1 ]]> 28.2 Fe, mg kg -1 ]] 50.2 Si, mg kg -1 ]] 5.2

[0091] After the vacuum residue is preheated to 70℃, oxalic acid and EDTA (mass ratio 2:1) are added to the vacuum residue as a demetallization agent, and the amount of addition is 150mg·kg -1 , and after mixing uniformly for 3h, ethylene glycol is added as a polyhydric alcohol extraction liquid, and then the vacuum residue is introduced into an inorganic membrane filter, the pore size of the ceramic filter membrane is selected to be 75μm, and the operating pressure is 1.2MPa, to remove the products generated by the reaction of the demetallization agent and trace elements, to obtain the purified vacuum residue.

[0092] The vacuum residue after removal of the metal is subjected to hydroprocessing, and the hydroprocessing reaction conditions are: reaction temperature 295℃, hydrogen partial pressure 1.7MPa, volume space velocity 0.55h -1 , hydrogen oil volume ratio 530Nm 3 / m 3 , to obtain the hydro-reduced residue oil.

[0093] The hydro-reduced residue is input into a delayed coking device for thermal cracking reaction, and the parameters of the thermal cracking reaction step are controlled to include: heating furnace outlet temperature 480°C, coke tower pressure 0.8 MPa, and circulation ratio 0.8; coking dry gas, coking gasoline and coking diesel, coking gas oil and petroleum coke can be obtained.

[0094] The properties of the petroleum coke are shown in Table 9, which shows that high-quality petroleum coke products can be prepared after the high-sulfur and high-metal crude oil is processed by the combined process of vacuum distillation-acid removal treatment-hydrorefining-delayed coking.

[0095] Table 9 Properties of petroleum coke products

[0096]

[0097] Comparative Example 1

[0098] In this example, a high-sulfur and high-metal crude oil is used as a raw material, and a vacuum residue is prepared by vacuum distillation (cutting temperature controlled at 480°C, vacuum degree 40 Pa), wherein 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 item sulfur content, m% 3.0 Ca, mg kg -1 ]] 50.2 Ni, mg·kg -1 ]] 45.2 V, mg·kg -1 ]]> 12.3 Fe, mg kg -1 ]] 25.3 Si, mg kg -1 ]] 3.5

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

[0102] Analysis item sulfur content, m% 4.1 Ca, mg kg -1 ]] 71.6 Ni, mg·kg -1 ]]> 60.5 V, mg·kg -1 ]]> 28.2 Fe, mg kg -1 ]] 50.2 Si, mg kg -1 ]] 5.2

[0103] The above vacuum residue is directly input into a coking device to produce petroleum coke, and the properties of the petroleum coke are shown in Table 12.

[0104] Table 12 Properties of petroleum coke products

[0105]

[0106] Comparative Example 2

[0107] In this example, a high-sulfur and high-metal crude oil is used as a raw material, and a vacuum residue is prepared by vacuum distillation (cutting temperature controlled at 480°C, vacuum degree 40 Pa), wherein 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 item sulfur content, m% 3.0 Ca, mg·kg -1 ]] 50.2 Ni, mg·kg -1 ]]> 45.2 V, mg·kg -1 ]]> 12.3 Fe, mg kg -1 ]]> 25.3 Si, mg kg -1 ]] 3.5

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

[0111] Analysis item sulfur content, m% Analysis item sulfur content, m% 4.1 Ca, mg kg -1 ]] 71.6 Ni, mg·kg -1 ]]> 60.5 V, mg·kg -1 ]]> 28.2 Fe, mg kg -1 ]] 50.2 Si, mg kg -1 ]] 5.2

[0112] After the vacuum residue is preheated to 70 DEG C, oxalic acid and EDTA (mass ratio 2:1) are added into the vacuum residue as demetallization agent, and the addition amount is 150 mg·kg -1 After mixing for 3 h, ethylene glycol is added as polyhydric alcohol extraction liquid, and then the vacuum residue is introduced into an inorganic membrane filter, the pore size of the ceramic filter membrane is 75 um, and the operating pressure is 1.2 MPa, so that the products generated by the reaction of the demetallization agent and trace elements are removed, and the purified vacuum residue is obtained.

[0113] Then, the obtained vacuum residue is directly introduced into a coking device to produce petroleum coke without hydrogenation treatment, and the properties of the petroleum coke are shown in Table 15.

[0114] Table 15 Product performance of petroleum coke

[0115]

[0116] As can be seen from the schemes of Comparative Examples 1 and 2, the petroleum coke prepared by directly introducing the vacuum residue obtained by hydrogenation treatment without demetallization into a coking device has high content of various metal elements, and the content of metal elements such as Na, V and Ni in the petroleum coke prepared by directly introducing the vacuum residue obtained by hydrogenation treatment of the crude oil only with demetallization into a coking device is still high.

[0117] It can be seen that the preparation method of the petroleum coke for special pre-baked anode provided by the application uses high-sulfur and high-metal crude oil as raw material, prepares vacuum residue by vacuum distillation, then uses a demetallization agent to treat the high-sulfur and high-metal vacuum residue, reacts organic Ca and Na salts in the vacuum residue to generate inorganic salts soluble in water, then uses an inorganic filter membrane with a hydrophilic modified internal surface to filter the demetallization-treated vacuum residue, removes most of the Ca and Na salts in the vacuum residue, then performs mild hydrogenation treatment on the vacuum residue, removes most of Ni, V and S in the vacuum residue, and at the same time, prolongs the service life of the hydrogenation protectant, so that the petroleum coke product with low metal content and sulfur content can be finally obtained. The preparation method of the petroleum coke for special pre-baked anode provided by the application uses the combination of the above processes for treatment, can use inferior crude oil to produce high-end petroleum coke for special pre-baked anode, expands the production raw material source of the petroleum coke, and improves the added value of inferior ethylene tar.

[0118] The above has carried out the detailed introduction to the embodiment of the application, the principle and implementation mode of the application have been described by applying specific examples in this paper, the above embodiment description is only used for helping understanding the method of the application and its core idea; at the same time, for the general technical personnel in the art, according to the idea of the application, there will be changes in specific implementation mode and application range, and the above is described, the content of the specification should not be understood as the limitation of the application.

Claims

1. A method for producing a special petroleum coke for prebaked anodes, characterized in that, The method comprises the following steps: (1) preparing vacuum residue by using high-sulfur and high-metal crude oil as raw material; (2) adding a metal removal agent into the vacuum residue, mixing, collecting the reaction product, and collecting the purified vacuum residue after extraction and filtration; the metal removal agent comprises oxalic acid and / or EDTA; (3) performing hydroprocessing on the purified vacuum residue to obtain hydroprocessed vacuum residue; (4) performing thermal cracking reaction on the obtained hydroprocessed vacuum residue to obtain petroleum coke; The property parameters of the vacuum residue are as follows: sulfur content 3-4.5 wt%, Ca content 60-80 mg·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 .

2. The method of producing the petroleum coke for the prebaked anode according to claim 1, characterized by, In the step (1), the high-sulfur and high-metal crude oil is subjected to vacuum distillation; The condition parameters of the vacuum distillation step include: cutting temperature of 400-540 ℃, and vacuum degree of 30-50 Pa; The property parameters of the high-sulfur and high-metal crude oil are as follows: sulfur content 2.0-3.5 wt%, Ca content 40-60 mg·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 .

3. The method of producing the petroleum coke for the prebaked anode according to claim 1 or 2, characterized by, In the step (2), the metal removal agent comprises a mixture of oxalic acid and EDTA; The metal removal agent comprises a mixture of oxalic acid and EDTA with a mass ratio of 1-3:1; The de-metallizing agent is added in an amount of 100-200 mg·kg -1 .

4. The method of producing the petroleum coke for the prebaked anode according to claim 3, characterized by, In the step (2), the extraction step comprises the step of adding an extractant for extraction; The extractant comprises a polyhydric alcohol solvent; The polyhydric alcohol solvent comprises ethylene glycol.

5. The method of producing the petroleum coke for the prebaked anode according to claim 3, characterized by, In the step (2), the vacuum residue is further subjected to preheating to 60-80 ℃; The filtration step comprises the step of filtering by using an inorganic membrane filter.

6. The process for the preparation of petroleum coke for prebaked anodes according to any one of claims 1-2, characterized in that, The hydrogenation reaction conditions in the step (3) include: reaction temperature 250-350℃, hydrogen partial pressure 1-5MPa, volume space velocity 1-10h -1 -2h -1 , hydrogen / oil volume ratio 300-400:

1.

7. The method of producing the petroleum coke for the prebaked anode according to claim 6, characterized by, In the step (3), the hydroprocessing step comprises the step of sequentially contacting the vacuum residue with a hydroprocessing guard catalyst and a hydrofining catalyst; The hydroprocessing guard catalyst comprises an alumina carrier and molybdenum and / or tungsten and nickel and / or cobalt supported on the alumina carrier; based on the total weight of the hydroprocessing guard catalyst, the content of the molybdenum and / or tungsten is 1-10 wt%, and the content of the nickel and / or cobalt is 0.5-3 wt% in terms of oxides; The hydrofining catalyst comprises a carrier and molybdenum and / or tungsten and nickel and / or cobalt supported on the carrier; based on the total weight of the catalyst, the content of the molybdenum and / or tungsten is 8-20 wt%, and the content of the nickel and / or cobalt is 0.3-8 wt% in terms of oxides; the carrier is alumina and / or silicon oxide.

8. The method of producing the petroleum coke for the prebaked anode according to claim 7, characterized by, In the step (3), the hydroprocessing step comprises the step of performing hydroprocessing based on a fixed-bed hydrogenation reactor; Based on the total loading volume of the catalyst in the fixed-bed hydrogenation reactor, the volume percentage of the hydroprocessing guard catalyst and the hydrofining catalyst is 2%-30% and 70%-98%, respectively.

9. The process for the preparation of petroleum coke for prebaked anodes according to any one of claims 1-2, characterized in that, In the step (4), the parameters of the thermal cracking reaction step include: heating furnace outlet temperature of 420 ℃-530 ℃, coke drum pressure of 0.2-1 MPa, and circulation ratio of 0.5-1; The thermal cracking reaction step is based on a delayed coking device.

10. A petroleum coke for special prebaked anodes, which is prepared by the method of any one of claims 1-9. The yield of the petroleum coke is greater than 45 wt%, the density of the petroleum coke is 2.08-2.13 g / cm 3 , the sulfur content of the petroleum coke is less than 0.5 wt%, the Ca content of the petroleum coke is <100 mg·kg -1 , the Fe content of the petroleum coke is <100 mg·kg -1 , the Na content of the petroleum coke is <50 mg·kg -1 , the Ni content of the petroleum coke is <100 mg·kg -1 , the Si content of the petroleum coke is <30 mg·kg -1 , the V content of the petroleum coke is <50 mg·kg -1 .

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