A method and system for producing low sulfur fuel oil

Abstract

The application discloses a method and system for preparing low-sulfur fuel oil. The method comprises the following steps: mixing inferior heavy oil, a catalyst and hydrogen to obtain a first mixed product, performing a shallow hydrocracking reaction on the first mixed product, and performing gas-liquid separation on the product obtained after the shallow hydrocracking reaction; mixing the liquid-phase product obtained after the gas-liquid separation with a composite flocculating agent to obtain a second mixed product, continuously depositing the second mixed product to obtain overflow material and underflow material; and performing a hydrodesulfurization treatment on the overflow material to prepare low-sulfur fuel oil. The inferior heavy oil is subjected to a shallow hydrocracking reaction, the reaction depth is controlled, and coking is avoided. The composite flocculating agent is added, so that the coking precursors such as asphaltene are separated before hydrodesulfurization, the raw material adaptability of the overflow component is improved, and the prepared low-sulfur fuel oil is high in stability and low in sulfur content.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of processing of inferior oil, in particular to a method and system for preparing low-sulfur fuel oil. BACKGROUND

[0002] According to the sulfur content standard of marine fuel oil, when the ship sails in the general area of the sea, the sulfur content of marine fuel oil should not exceed 0.5%; when sailing in the emission control area, the sulfur content of marine fuel oil should not exceed 0.1%. At present, the supply of fuel oil that can meet the requirements in the market is limited, and the existing production capacity is difficult to meet the market demand. From the current actual situation, although the existing low-sulfur distillate type fuel oil resources can realize large-scale production, the oil product cannot be completely matched with the ship equipment. Once used on the medium and low speed diesel engine of the ship for a long time, it will bring great test to the fuel conversion system and equipment of the ship, and also bring greater safety risk. Moreover, the crude oil resources in the world are gradually becoming heavy and inferior, but the existing production method for producing low-sulfur fuel oil from inferior heavy oil has many deficiencies.

[0003] The existing method for preparing low-sulfur fuel oil generally includes:

[0004] The viscosity-reducing cracking is combined with the fixed bed hydrogenation device, and the overflow material is added to the fixed bed hydrogenation by the method of flocculation and precipitation to prepare low-sulfur fuel oil. The defect of this preparation method is that the processing depth of the viscosity-reducing cracking is not high, the metal removal and desulfurization and denitrification performance of the raw material are poor, the properties of the overflow material are relatively poor, the adaptability of the fixed bed raw material is poor, and the use process of the fixed bed hydrogenation device will have a great impact.

[0005] The slurry bed hydrogenation is coupled with the fixed bed hydrogenation, the wax oil fraction content in the slurry bed hydrogenation feed is adjusted, the hydrogen distributor is set, the high-activity transition metal catalyst is used, and the dry point value of the wax oil fraction in the fixed bed hydrogenation feed is limited, so that the deep hydrogenation of inferior heavy oil is realized, and low-sulfur fuel oil is prepared. However, in this preparation method, the operating temperature of the slurry bed is high, a large amount of coke will be generated when processing inferior heavy oil, which will affect the stability of the subsequent operation and the operation cycle of the device, and the desulfurization effect is also poor.

[0006] Moreover, for the method of directly producing low-sulfur fuel oil by the slurry bed which occurs hydrogen thermal cracking reaction, the stability of the prepared fuel oil is not high, and due to the process condition limitation, if inferior high-sulfur raw material is used to prepare fuel oil, the sulfur content of the fuel oil directly produced by the slurry bed is too high. Compared with the slurry bed, the fixed bed has higher requirements for raw materials, and cannot directly process inferior oil raw materials. SUMMARY

[0007] The existing method for preparing low-sulfur fuel oil has poor desulfurization effect on the preparation raw material, and has the risk of coking and blocking the reaction equipment, resulting in poor system operation stability.

[0008] In view of the above problems, the present application is proposed in order to provide a method and system for preparing low-sulfur fuel oil which overcomes the above problems or at least partially solves the above problems.

[0009] In a first aspect, the embodiments of the present application provide a method for preparing low-sulfur fuel oil, comprising:

[0010] Mixing the inferior heavy oil, the catalyst and hydrogen to obtain a first mixed product, performing a shallow hydrocracking reaction on the first mixed product, and performing gas-liquid separation on the product obtained after the shallow hydrocracking reaction;

[0011] Mixing the liquid-phase product after the gas-liquid separation and a composite flocculant to obtain a second mixed product, and performing continuous deposition on the second mixed product to obtain overflow material and underflow material;

[0012] Performing hydrodesulfurization treatment on the overflow material to prepare low-sulfur fuel oil.

[0013] In an embodiment, after obtaining the underflow material, the method further comprises:

[0014] Mixing the underflow material and an aromatic hydrocarbon component-rich mixture to obtain a third mixed product, and performing solid-liquid separation on the third mixed product;

[0015] Mixing the back-extracted material obtained by the solid-liquid separation and the inferior heavy oil and the catalyst to obtain a fourth mixed product;

[0016] Mixing the fourth mixed product and hydrogen to obtain the first mixed product.

[0017] In an embodiment, the shallow hydrocracking reaction on the first mixed product comprises:

[0018] Performing the hydrocracking reaction on the first mixed product under the conditions of a reaction temperature of 350-420℃ and a reaction pressure of 4-14Mpa, wherein the hydrogen-oil volume ratio at the reactor inlet is 600-2000, the catalyst usage per gram of inferior heavy oil is 100-10000μg, the volume space velocity is 0.5-2h -1 , and the single-pass conversion rate is 30-60wt%.

[0019] In an embodiment, the shallow hydrocracking reaction on the first mixed product comprises:

[0020] The first mixed product is subjected to a hydrocracking reaction under the conditions of a reaction temperature of 400-420 DEG C and a reaction pressure of 10-12 MPa, wherein the hydrogen-oil volume ratio at the reactor inlet is 1000-1500, the catalyst usage corresponding to per gram of poor heavy oil is 100-5000 mu g, the volume space velocity is 1-1.5 h -1 , and the single-pass conversion rate is 40-50 wt%.

[0021] In one embodiment, the composite flocculant is added in an amount of 0.01-0.2% of the weight of the liquid phase product;

[0022] The composite flocculant comprises: a quaternary ammonium salt surfactant, an organic high molecular flocculant, an inorganic high molecular flocculant, and a reverse oil-soluble demulsifier, and the weight ratio of the four is 1-10:1-5:10-200:1-100;

[0023] The quaternary ammonium salt surfactant comprises one or a combination of several of: dicetyl dimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, alkyl dimethyl ammonium chloride, and octadecyl trimethyl ammonium bromide;

[0024] The organic high molecular flocculant comprises one or a combination of several of: cationic polyacrylamide, sodium polyacrylate, polyvinylpyridine, and polyethyleneimine;

[0025] The inorganic high molecular flocculant comprises one or a combination of several of: polymeric aluminum ferric silicate, polymeric aluminum ferric sulfate, polymeric aluminum silicate, and polymeric aluminum ferric phosphate;

[0026] The reverse oil-soluble demulsifier comprises one or a combination of several of: a polyether reverse oil-soluble demulsifier, a polypropylene oxide reverse oil-soluble demulsifier, a polyamide reverse oil-soluble demulsifier, and a polytriethanolamine reverse oil-soluble demulsifier.

[0027] In one embodiment, the composite flocculant is added in an amount of 0.05-0.1% of the weight of the liquid phase product;

[0028] The composite flocculant comprises: dicetyl dimethyl ammonium bromide, cationic polyacrylamide, polyaluminum silicate, and a polyether reverse oil-soluble demulsifier, and the weight ratio of the four is 5-10:1-3:50-100:10-50.

[0029] In one embodiment, the continuous deposition of the second mixed product comprises: using a continuous deposition device, and performing continuous deposition at a temperature of 100-200 DEG C through liquid-liquid separation.

[0030] In one embodiment, the inferior heavy oil includes one or a combination of atmospheric residue, vacuum residue, deasphalted oil, oil sand bitumen, high-viscosity crude oil, coal tar, and coal liquefaction heavy oil.

[0031] In one embodiment, the catalyst is a solid powder catalyst, a water-soluble catalyst, an oil-soluble catalyst, or a microemulsion catalyst.

[0032] In one embodiment, the overflow material is subjected to hydrodesulfurization treatment, including: using one or a combination of a hydrogen protective agent, a hydrodemetallization catalyst, and a hydrodesulfurization catalyst to treat the overflow material; the hydrodemetallization catalyst and the hydrodesulfurization catalyst contain an active metal and a carrier; the active metal contains at least one of a Group VI metal and / or a Group VIII metal; the carrier contains at least one of alumina, amorphous silica-alumina, and silicon dioxide.

[0033] In one embodiment, the mass ratio of the underflow material to the aromatic component-rich material is 1:1-10.

[0034] The aromatic component-rich material includes one or a combination of catalytic diesel, catalytic slurry oil, and naphthenic base crude oil.

[0035] In one embodiment, the third mixture is subjected to solid-liquid separation, including: using a solid-liquid separation device to perform solid-liquid separation treatment at an operating temperature of 100-200°C.

[0036] In a second aspect, an embodiment of the present application provides a system for preparing low-sulfur fuel oil, including: an enhanced hydrogen mixing device, a slurry bed reactor, a gas-liquid separation device, a continuous deposition device, and a fixed bed reactor.

[0037] The enhanced hydrogen mixing device is configured to mix inferior heavy oil, a catalyst, and hydrogen to obtain a first mixture.

[0038] The slurry bed reactor is connected to the enhanced hydrogen mixing device and is configured to perform a shallow hydrocracking reaction on the first mixture.

[0039] The gas-liquid separation device is connected to the slurry bed reactor and is configured to perform gas-liquid separation on the product obtained after the shallow hydrocracking reaction.

[0040] The continuous deposition device is connected to the gas-liquid separation device and is configured to mix the liquid-phase product obtained after the gas-liquid separation with a composite flocculant to obtain a second mixture, and to perform continuous deposition on the second mixture to obtain overflow material and underflow material.

[0041] The fixed bed reactor is configured to perform hydrodesulfurization treatment on the overflow material to prepare low-sulfur fuel oil.

[0042] In one embodiment, the system for preparing low-sulfur fuel oil further comprises a solid-liquid separation device and a mixing device;

[0043] The solid-liquid separation device is connected with the continuous deposition device, and is used for mixing the underflow material and the aromatic hydrocarbon component to obtain a third mixed product; and the third mixed product is subjected to solid-liquid separation;

[0044] The mixing device is connected with the solid-liquid separation device, and is used for mixing the recycled material obtained through solid-liquid separation, the inferior heavy oil and the catalyst to obtain a fourth mixed product;

[0045] The enhanced hydrogen mixing device is further used for mixing the fourth mixed product and hydrogen to obtain a first mixed product.

[0046] In a third aspect, an embodiment of the present application provides a low-sulfur fuel oil prepared by using the method for preparing low-sulfur fuel oil as described above.

[0047] The beneficial effects of the above technical solutions provided by the embodiments of the present application at least include:

[0048] The method and system for preparing low-sulfur fuel oil provided by the embodiments of the present application control the reaction depth by using a slurry bed hydrogenation reactor to perform shallow hydrogenation cracking reaction on inferior heavy oil through a lower temperature and a higher space velocity, avoid the generation of coke, add a composite flocculating agent by using the characteristics that the shallow hydrogenation cracking residue oil has poor compatibility and the colloidal system is unstable, further destroy the colloidal stability, improve the separation speed and separation efficiency, make the asphaltene and other easy-coking precursors aggregate and separate before entering the fixed bed hydrogenation reactor, separate most of the asphaltene, obtain overflow material with greatly reduced asphaltene content, so that the overflow material from which most of the asphaltene is removed becomes a good fixed bed hydrogenation raw material, improves the adaptability of the fixed bed raw material, improves the stability of the fixed bed operation, increases the operation cycle, and the prepared low-sulfur fuel oil is removed from most of the asphaltene, has higher stability and lower sulfur content.

[0049] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure particularly pointed out in the written description, claims, and drawings.

[0050] The technical solutions of the present application will be further described in detail below with the help of drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0051] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and are used to explain the present application, but are not intended to limit the present application. In the drawings:

[0052] Figure 1 Flow chart of the method for preparing low-sulfur fuel oil in the embodiment of the present application;

[0053] Figure 2 Process flow chart of the system for preparing low-sulfur fuel oil in the embodiment of the present application;

[0054] Explanation of reference signs:

[0055] 1 - hydrogenation device, 2 - slurry bed reactor, 3 - gas-liquid separation device,

[0056] 4 - continuous deposition device, 5 - solid-liquid separation device, 6 - fixed bed reactor, 7 - raw oil (low-quality heavy oil), 8 - catalyst, 9 - hydrogen, 10 - composite flocculant, 11 - aromatic component-rich. DETAILED DESCRIPTION

[0057] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and so that the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0058] The embodiment of the present application provides a method for preparing low-sulfur fuel oil, the flow chart thereof is shown in Figure 1 and includes:

[0059] S11, mixing low-quality heavy oil, catalyst and hydrogen to obtain a first mixed product, performing a shallow hydrocracking reaction on the first mixed product, and performing gas-liquid separation on the product obtained after the shallow hydrocracking reaction;

[0060] S12, mixing the liquid phase product after the gas-liquid separation with a composite flocculant to obtain a second mixed product, performing continuous deposition on the second mixed product to obtain overflow material and underflow material;

[0061] S13, performing a hydrodesulfurization treatment on the overflow material to prepare low-sulfur fuel oil.

[0062] The method for preparing low-sulfur fuel oil in the embodiment of the present application utilizes the unstable characteristics of the shallow thermal cracking residue colloid system to separate the asphaltene and other coking precursors before hydrogenation desulfurization treatment, so that the overflow material is separated from most of the asphaltene, the properties of the overflow material are improved, the coking risk is greatly reduced, the prepared low-sulfur fuel oil has a lower sulfur content and more stable properties.

[0063] In the above method, the liquid phase product after gas-liquid separation is mixed with the composite flocculant, and the treatment process of the gas phase product obtained after gas-liquid separation is not limited.

[0064] Optionally, after obtaining the underflow material in the above step S12, the following steps can be further included:

[0065] The underflow material is mixed with the aromatic hydrocarbon component to obtain a third mixed product; and the third mixed product is subjected to solid-liquid separation;

[0066] The back-extracted material obtained by the solid-liquid separation is mixed with the inferior heavy oil and the catalyst to obtain a fourth mixed product;

[0067] The fourth mixed product is mixed with hydrogen to obtain the first mixed product.

[0068] In the above method, the underflow material contains flocculated asphaltene and coking particles, and mixing the underflow material with the aromatic hydrocarbon component can cause most of the asphaltene to be redissolved in the aromatic hydrocarbon component, thereby reducing the coking in the subsequent reaction. In addition, the underflow material and the aromatic hydrocarbon component contain some solid impurity particles, and the solid-liquid separation can remove these solid impurity particles. The product obtained after removing the solid impurity particles is the back-extracted material. The back-extracted material is mixed with the inferior heavy oil and the catalyst again, and then the obtained mixture is mixed with hydrogen to obtain the first mixed product, which can be back-extracted again through the steps of S11, S12 and S13. Through back-extraction, the overall product yield can be improved.

[0069] The first mixed product can be a mixed product of the inferior heavy oil, the catalyst and hydrogen, or a mixed product of the inferior heavy oil, the catalyst, hydrogen and the back-extracted material.

[0070] Optionally, in the above step S11, the first mixed product is subjected to shallow hydrogenation cracking reaction, for example, under the following reaction conditions:

[0071] The first mixed product is subjected to hydrogenation cracking reaction under the conditions of a reaction temperature of 350-420 DEG C and a reaction pressure of 4-14 MPa, wherein the hydrogen / oil volume ratio at the reactor inlet is 600-2000, the catalyst dosage corresponding to each gram of inferior heavy oil is 100-10000 ug, and the volume space velocity is 0.5-2 h-1.-1 The single pass conversion rate is 30-60wt%.

[0072] The catalyst dosage is calculated based on the metal content, for example, the Mo catalyst dosage is 300ppm, i.e. 300ug of Mo per gram of poor heavy oil.

[0073] Optionally, in the step S11, the first mixed product is subjected to a shallow hydrocracking reaction, which can be carried out under the following reaction conditions, which are the preferred reaction conditions:

[0074] The first mixed product is subjected to a hydrocracking reaction under the conditions of a reaction temperature of 400-420℃ and a reaction pressure of 10-12MPa, wherein the hydrogen oil volume ratio at the reactor inlet is 1000-1500, the catalyst dosage corresponding to each gram of poor heavy oil is 100-5000ug, and the volume space velocity is 1-1.5h -1 The single pass conversion rate is 40-50wt%.

[0075] Optionally, in the step S12, the composite flocculant is added in an amount of 0.01-0.2% of the weight of the liquid phase product;

[0076] The composite flocculant can include, for example, a quaternary ammonium salt surfactant, an organic polymer flocculant, an inorganic polymer flocculant, and a reverse oil-soluble demulsifier, in a weight ratio of 1-10:1-5:10-200:1-100;

[0077] The quaternary ammonium salt surfactant can include, for example, one or a combination of several of dicetyl dimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, alkyl dimethyl ammonium chloride, and octadecyl trimethyl ammonium bromide;

[0078] The organic polymer flocculant can include, for example, one or a combination of several of cationic polyacrylamide, sodium polyacrylate, polyvinylpyridine salt, and polyethyleneimine;

[0079] The inorganic polymer flocculant can include, for example, one or a combination of several of polymeric aluminum ferric silicate, polymeric aluminum ferric sulfate, polymeric aluminum silicate, and polymeric aluminum ferric phosphate;

[0080] The reverse oil-soluble demulsifier can include, for example, one or a combination of several of a polyether reverse oil-soluble demulsifier, a polypropylene oxide reverse oil-soluble demulsifier, a polyamide reverse oil-soluble demulsifier, and a polytriethanolamine reverse oil-soluble demulsifier.

[0081] Optionally, in the step S12, the composite flocculant is added in an amount of 0.05-0.1% of the weight of the liquid phase product;

[0082] The composite flocculant may include, for example, dihexadecyl dimethyl ammonium bromide, cationic polyacrylamide, polyaluminum ferric silicate, and polyether reverse oil-soluble demulsifier, and the weight ratio of the four is 5-10:1-3:50-100:10-50.

[0083] The dihexadecyl dimethyl ammonium bromide can make the asphaltene polymer long-chain curl or agglomerate to reduce viscosity, the polyether reverse oil-soluble demulsifier can make the colloid-wrapped asphaltene demulsify, and the polyaluminum ferric silicate and the cationic polyacrylamide can enhance the flocculation effect, so that the flocculation body of the agglomerated asphaltene is flocculated and settled, and the asphaltene is separated.

[0084] Optionally, in the step S12, the second mixed product is continuously deposited, for example, a continuous deposition device can be used, and the continuous deposition is performed at a temperature of 100-200°C by liquid-liquid separation, for example, the weight yield of the overflow material is 70-90% based on 100% of the total weight of the second mixed product.

[0085] Optionally, in the step S11, the inferior heavy oil may include, for example, one or a combination of several of atmospheric residue, vacuum residue, deasphalted oil, oil sand bitumen, high-viscosity crude oil, coal tar, and coal liquefaction heavy oil.

[0086] In the inferior heavy oil, the total weight of the metal content is greater than 200ug / g based on the total weight of Ni and V, and the total content of colloid and asphaltene is greater than 30wt%.

[0087] The catalyst may be a slurry bed catalyst commonly used in the art, for example, a solid powder catalyst, a water-soluble catalyst, an oil-soluble catalyst, or a microemulsion catalyst, and the particle size of the catalyst is 0.01-100μm. In the embodiments of the present application, the catalyst may be, for example, an oil-soluble molybdenum catalyst.

[0088] Optionally, in the step S13, the overflow material is subjected to hydrodesulfurization treatment, for example, one or several of a hydrogenation protective agent, a hydrodemetallization catalyst, and a hydrodesulfurization catalyst can be used to treat the overflow material; the hydrodemetallization catalyst and the hydrodesulfurization catalyst contain active metals and carriers; the active metals contain at least one of Group VI metals and / or Group VIII metals; and the carrier contains at least one of alumina, amorphous silica-alumina, and silicon dioxide.

[0089] Optionally, in the method, the mass ratio of the underflow material to the aromatic hydrocarbon component-rich material is 1:1-10; the aromatic hydrocarbon component-rich material may include, for example, one or several of catalytic diesel, catalytic slurry oil, and naphthenic base crude oil.

[0090] Optionally, in the above method, the third mixture is subjected to solid-liquid separation, for example, a solid-liquid separation device can be used, and the solid-liquid separation is performed at a temperature of 100-200 DEG C in a solid-liquid separation mode, and the solid-liquid separation device can be a continuous solid-liquid separation device.

[0091] Optionally, in the above method, the gas-liquid separation operation and its process conditions are not limited, for example, the gas-liquid separation can be performed by thermal high separation or other modes.

[0092] The embodiment of the present application also provides a system for preparing low-sulfur fuel oil, comprising: a reinforced hydrogen mixing device 1, a slurry bed reactor 2, a gas-liquid separation device 3, a continuous deposition device 4 and a fixed bed reactor 6.

[0093] The reinforced hydrogen mixing device 1 is used for mixing inferior heavy oil 7, a catalyst 8 and hydrogen 9 to obtain a first mixture.

[0094] The slurry bed reactor 2 is connected with the reinforced hydrogen mixing device 1, and is used for performing a shallow hydrocracking reaction on the first mixture.

[0095] The gas-liquid separation device 3 is connected with the slurry bed reactor 2, and is used for performing gas-liquid separation on the product obtained after the shallow hydrocracking reaction.

[0096] The continuous deposition device 4 is connected with the gas-liquid separation device 3, and is used for mixing the liquid-phase product after the gas-liquid separation with a composite flocculant 10 to obtain a second mixture, and performing continuous deposition on the second mixture to obtain overflow material and underflow material.

[0097] The fixed bed reactor 6 is used for performing a hydrodesulfurization treatment on the overflow material to prepare low-sulfur fuel oil.

[0098] The embodiment of the present application uses the reinforced hydrogen mixing device 1, increases the hydrogen mass transfer efficiency, and reduces the reaction pressure.

[0099] The system for preparing low-sulfur fuel oil provided by the embodiment of the present application can also solve the following problems: for general thermal cracking reaction, with the reaction proceeding, the saturated components and the asphaltene increase with the cracking and polymerization of the aromatic components and the resin, while the structural change of each component occurs, the mass flow also exists between each component, such as the disproportionation reaction of the resin which converts the resin into the saturated components and the asphaltene, the conversion of the aromatic components into the asphaltene, etc., which will result in the destruction of the adsorption balance between the asphaltene and the resin, the loss of the peptization state of the asphaltene and the formation of the flocculation state of the precipitate, the formation of the so-called second liquid phase, the deposition on the surface of the furnace tube and the reactor wall, and the conversion into coke. For the above problems, the embodiment of the present application controls the reaction depth by performing the shallow hydrocracking of the inferior heavy oil 7 in the slurry bed reactor 2 at a lower temperature and a higher space velocity, avoids the further condensation of the coking precursor (the so-called second liquid phase) to produce coke, and adds the composite flocculating agent 10 to further destroy the colloidal stability and improve the separation speed and the separation efficiency of the inferior heavy oil 7 by using the poor compatibility of the shallow hydrocracking residue and the unstable colloidal system, so that the asphaltene and other coking precursors are separated and gathered before entering the fixed bed reactor 6. Since most of the sulfur, nitrogen, oxygen and metals in the residue are concentrated in the heavy resin and the asphaltene, the overflow component separated from the asphaltene becomes a good fixed bed hydrogenation raw material, the stability of the fixed bed operation is improved, the operation cycle is increased, and the stability of the low-sulfur fuel oil generated is also greatly improved due to the removal of most of the asphaltene.

[0100] Optionally, the system for preparing low-sulfur fuel oil can further comprise a solid-liquid separation device 5 and a mixing device.

[0101] The solid-liquid separation device 5 is connected with the continuous deposition device 4, and is used for mixing the underflow material with the aromatic component-rich component 11 to obtain a third mixed product; and performing solid-liquid separation on the third mixed product.

[0102] The mixing device is connected with the solid-liquid separation device 5, and is used for mixing the recycled material obtained by the solid-liquid separation with the inferior heavy oil 7 and the catalyst 8 to obtain a fourth mixed product.

[0103] The enhanced hydrogen mixing device 1 is further used for mixing the fourth mixed product with the hydrogen 9 to obtain the first mixed product.

[0104] The mixing device is an optional device, and in actual application, the mixing device can also not be arranged, and the recycled material after the solid-liquid separation is mixed with the inferior heavy oil 7 and the catalyst 8 respectively to enter the enhanced hydrogen mixing device 1 to be mixed with the hydrogen 9.

[0105] The present application mixes the deposited asphaltene and other heavy components in the continuous deposition device 4 with the catalytic oil slurry and other components rich in aromatic hydrocarbons, since the catalytic oil slurry and other components such as catalytic diesel oil are rich in gum and aromatic hydrocarbons, after adding the deposited asphaltene and other heavy components, the whole colloidal system reaches a new phase state stability, and can return to the slurry bed reactor 2 for shallow hydrocracking and coking inhibition, and can also solve the outlet problem of the catalytic oil slurry and other difficult-to-process secondary conversion generated oil.

[0106] Referring to Figure 2 As shown in the figure, Figure 2 The process flow diagram of the system for preparing low-sulfur fuel oil in the embodiment of the present application, the enhanced hydrogen mixing device 1 is provided with a first inlet, a second inlet and an outlet, the inferior heavy oil raw material 7 and the catalyst 8 enter from the first inlet, the slurry bed reactor 2 is provided with an inlet and an outlet, the outlet of the enhanced hydrogen mixing device 1 is in communication with the inlet of the slurry bed reactor 2, the outlet of the slurry bed reactor 2 is in communication with the inlet of the gas-liquid separation device 3, the liquid phase outlet of the gas-liquid separation device 3 is in communication with the inlet of the continuous deposition device 4, the overflow material outlet of the continuous deposition device 4 is in communication with the inlet of the fixed bed reactor 6, the underflow material outlet of the continuous deposition device 4 is in communication with the inlet of the solid-liquid separation device 5, the liquid outlet of the solid-liquid separation device 5 is in communication with the inlet of the mixing device (not shown in the figure), and the outlet of the mixing device is in communication with the first inlet of the enhanced hydrogen mixing device 1. Figure 2

[0107] The enhanced hydrogen mixing device 1 may, for example, be a micro-channel device, a supergravity device, a jet device or an ultrasonic device.

[0108] The continuous deposition device 4 may, for example, be a conical thickener or a high-efficiency thickener.

[0109] The gas-liquid separation device 3 may, for example, be a hydrocyclone.

[0110] In the present application, the enhanced hydrogen mixing device 1, the slurry bed reactor 2, the gas-liquid separation device 3 (for example: thermal high separation), the continuous deposition device 4, the solid-liquid separation device 5 and the fixed bed reactor 6 may all be conventional devices used in the art, and the operating conditions of the fixed bed reactor 6 may be general industrial conditions.

[0111] The embodiment of the present application also provides a low-sulfur fuel oil prepared by using the method for preparing low-sulfur fuel oil as described above.

[0112] The present application will be further described in detail below in combination with specific examples, and the implementability of the method for preparing low-sulfur fuel oil in the present application will be illustrated by experimental data. However, the embodiments of the present application are not limited thereto:

[0113] The properties of the vacuum residue raw material are shown in Table 1:

[0114] ​Table 1 Properties of vacuum residue feedstock

[0115]

[0116]

[0117] Examples 1-6 and Comparative Examples 1-3 adopted Figure 2 The process flow for preparing low-sulfur fuel oil, combined with Figure 2 The actual operation process of the embodiments and comparative examples of the present invention will be described in detail.

[0118] Example 1

[0119] The vacuum residue feedstock and oil-soluble molybdenum catalyst (a conventional catalyst used in the art), namely feedstock oil 7 and catalyst 8, are fed into the enhanced hydrogen mixing unit 1 and fully mixed with hydrogen 9 in the enhanced hydrogen mixing unit 1. The resulting mixture is fed into the slurry bed reactor 2 for shallow hydrocracking reaction. The product obtained from the reaction is subjected to high-pressure gas-liquid separation in the gas-liquid separation unit 3 to obtain the liquid phase product. The property parameters of the liquid phase product obtained in this embodiment are shown in Table 3.

[0120] A composite flocculant 10 is added to the liquid phase product. The amount of composite flocculant 10 added is 0.05% of the weight of the liquid phase product. The composite flocculant 10 is composed of a mixture of hexadecyl dimethyl ammonium bromide, cationic polyacrylamide, polyaluminum ferric silicate, and polyether-based reverse oil-soluble demulsifier in a weight ratio of 6:1:50:40. The resulting mixture is subjected to continuous deposition separation in a continuous deposition apparatus 4 at an operating temperature of 150°C. After the operation, overflow material is obtained at the overflow material outlet of the continuous deposition apparatus 4 with a weight yield of 80%. Underflow material is obtained at the underflow material outlet of the continuous deposition apparatus 4. The underflow material is oil rich in asphaltene.

[0121] The underflow material is sent to the solid-liquid separation device 5 and mixed with the catalytic oil slurry 11. The operating temperature is 150°C and the mass ratio of the underflow material to the catalytic oil slurry 11 is 1:2. After filtering out solid impurities, the resulting mixture is sent to the enhanced hydrogen mixing device 1 and fully mixed with hydrogen in the enhanced hydrogen mixing device 1. The resulting mixture is then sent to the slurry bed reactor 2 for reprocessing.

[0122] The overflow material is fed into a fixed-bed reactor 6 for hydrodesulfurization. The fixed-bed reactor 6 is filled with a hydroprotectant, a hydrodemetallization catalyst, and a hydrodesulfurization catalyst to produce low-sulfur fuel oil.

[0123] Example 2

[0124] The difference between Example 2 and Example 1 is that the amount of composite flocculant 10 added is 0.07% of the weight of the liquid product. The weight ratio of dihexadecyldimethylammonium bromide, cationic polyacrylamide, polyaluminum ferric silicate, and polyether-based reverse oil-soluble demulsifier in composite flocculant 10 is 3:1:25:20. The difference in reaction conditions between the slurry bed reactors of Example 2 and Example 1 is shown in Table 2. The property parameters of the liquid product obtained in this example are shown in Table 3.

[0125] Example 3

[0126] The difference between Example 3 and Example 1 is that the amount of composite flocculant 10 added is 0.1% of the weight of the liquid product. The weight ratio of the composite flocculant 10, namely, dihexyldimethylammonium bromide, cationic polyacrylamide, polyaluminum ferric silicate, and polyether-based reverse oil-soluble demulsifier, is 10:1:50:50. The difference in reaction conditions between the slurry bed reactors of Example 3 and Example 1 is shown in Table 2. The property parameters of the liquid product obtained in this example are shown in Table 3.

[0127] Example 4

[0128] The difference between Example 4 and Example 1 is that the amount of composite flocculant 10 added is 0.01% of the weight of the liquid product, the operating temperature of the continuous deposition device 4 is 100°C, the weight yield of the overflow material is 70%, and the operating temperature of the solid-liquid separation device 5 is 100°C. The difference in reaction conditions between the slurry bed reactors of Example 4 and Example 1 is shown in Table 2. The property parameters of the liquid product obtained in this example are shown in Table 3.

[0129] Example 5

[0130] The difference between Example 5 and Example 1 is that the amount of composite flocculant 10 added is 0.2% of the weight of the liquid phase product, the operating temperature of the continuous deposition device 4 is 200°C, the weight yield of the overflow material is 90%, and the operating temperature of the solid-liquid separation device 5 is 200°C. The property parameters of the liquid phase product obtained in this example are shown in Table 3.

[0131] Example 6

[0132] The only difference between Example 6 and Example 1 is that the reaction conditions of the slurry bed reactor are different. The difference in reaction conditions of the slurry bed reactor between Example 6 and Example 1 is shown in Table 2. The property parameters of the liquid phase product obtained in this example are shown in Table 3.

[0133] Comparative Example 1

[0134] The difference between Comparative Example 1 and Example 1 is that the operating conditions of the slurry bed reactor are not mild hydrocracking conditions. The specific operating conditions are shown in Table 2. The property parameters of the liquid phase product obtained in this comparative example are shown in Table 3.

[0135] Comparative Example 2

[0136] The difference between Comparative Example 2 and Example 1 is that the added composite flocculant 10 contains only cationic polyacrylamide and polyaluminum ferric silicate, and the weight ratio of the two is 1:50.

[0137] Comparative Example 3

[0138] The difference between Comparative Example 3 and Example 1 is that the underflow material was not mixed with the catalytic oil slurry, but was directly returned to the slurry bed reactor 2 for reprocessing. The property parameters of the liquid phase product obtained in this comparative example are shown in Table 3.

[0139] The operating conditions of the slurry bed reactor are shown in Table 2 below, the property parameters of the liquid phase product are shown in Table 3 below, the property parameters of the overflow material are shown in Table 4 below, the operating conditions and product properties of the fixed bed reactor are shown in Table 5 below, and the standards for residual fuel oil are shown in Table 6 below.

[0140] Table 2 Operating conditions of slurry bed reactor

[0141]

[0142] Table 3. Property parameters of liquid phase products

[0143]

[0144]

[0145] Table 4. Properties of Overflow Material

[0146]

[0147]

[0148] Table 5 Operating conditions and product properties of fixed-bed reactors

[0149]

[0150] Table 6 Residual Fuel Oil Standard (GB17411)

[0151]

[0152] The feed requirements for fixed-bed reactor 6 are generally metal (Ni+V) ≤120ug / g and residual carbon ≤12wt%. As shown in the results of the examples in Table 4, high-carbon, high-metal-content inferior heavy oil, which cannot be processed by fixed-bed hydrocracking, yields overflow material with good properties after continuous settling using the method of this invention (i.e., moderate hydrocracking and composite modifiers), meeting the feedstock requirements of the fixed-bed hydrocracking process. Furthermore, as can be seen from Table 5 (fixed-bed product properties) and Table 6, the method of this invention can produce Group II low-sulfur fuel oil that meets national standards.

[0153] By comparing the operating conditions of Example 1 and Comparative Example 1 shown in Table 2, it can be seen that the slurry bed in Example 1 of this invention uses mild hydrocracking process conditions, while Comparative Example 1 uses conventional hydrocracking conditions in general industry. As can be seen from the toluene insoluble content of the products of Example 1 and Comparative Example 1 in Table 3, the toluene insoluble content of the liquid phase product obtained in Example 1 is only 0.05 wt%, while the toluene insoluble content of the liquid phase product of Comparative Example 1 is 2.12 wt%. Excessive toluene insoluble content will easily lead to coking and blockage of subsequent pipelines and rapid coking of subsequent fixed bed catalysts, resulting in a rapid increase in bed pressure drop, which in turn affects the operation cycle of the entire unit.

[0154] Comparing the experimental data of Example 1 and Comparative Example 2 shown in Tables 4 and 5 above, it can be seen that the composite modified flocculant used in Example 1 of this invention, compared with the industrially commonly used cationic metal flocculant used in Comparative Example 2, enhances the flocculation effect of the cationic flocculant, causing the agglomerated asphaltene flocs to flocculate and settle, significantly reducing the asphaltene content in the overflow component. Since most of the difficult-to-remove sulfides in residual oil are present in asphaltene, under the same fixed-bed operating conditions, the sulfur content of the final product of Example 1 is 0.37 wt%, meeting the national standard requirement of less than 0.5 wt%. However, due to less asphaltene flocculation, the sulfur content of the product of Comparative Example 2 is 0.63 wt%, exceeding the national standard requirement.

[0155] To ensure the overall liquid yield of the system, the underflow component (accounting for 10-30 wt% of the total feed) is usually recycled. As can be seen from the comparison between Example 1 and Comparative Example 3 in Table 3, the toluene-insoluble content of the liquid phase product obtained in Example 1 is only 0.05 wt%, while the toluene-insoluble content of the liquid phase product in Comparative Example 3 is 1.56 wt%. This is because flocculated asphaltene is a precursor to coke. If the asphaltene-rich underflow component is directly recycled, it will lead to the enrichment of asphaltene in the slurry bed reaction, resulting in the generation of a large amount of toluene-insoluble matter under the same operating conditions. However, Example 1 uses the aromatic hydrocarbon-rich component to mix with the underflow component, so that the flocculated asphaltene is redissolved in the aromatic hydrocarbon component, and the entire colloidal system is restored to phase equilibrium. Therefore, the amount of coke generated during the reaction process is greatly reduced.

[0156] The above embodiments are typical examples listed to illustrate the technical solution of the present invention in detail. The present invention shall be subject to the protection scope of the claims and the specification, and shall not be limited by the described embodiments. Simple substitutions or modifications to the present invention shall still be within the protection scope of the present invention.

[0157] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing low-sulfur fuel oil, characterized in that, include: Inferior heavy oil, catalyst and hydrogen are mixed to obtain a first mixed product. The first mixed product is subjected to shallow hydrocracking reaction. The product obtained after shallow hydrocracking reaction is subjected to gas-liquid separation. The liquid phase product after gas-liquid separation is mixed with a composite flocculant to obtain a second mixed product. The second mixed product is continuously deposited to obtain overflow material and underflow material. The composite flocculant includes: quaternary ammonium salt surfactant, organic polymer flocculant, inorganic polymer flocculant and reverse oil-soluble demulsifier, with a weight ratio of 1-10:1-5:10-200:1-100. The overflow material is subjected to hydrodesulfurization treatment to produce low-sulfur fuel oil.

2. The method as described in claim 1, characterized in that, After obtaining the underflow material, the process also includes: The underflow material is mixed with an aromatic hydrocarbon-rich component to obtain a third mixed product; the third mixed product is then subjected to solid-liquid separation. The recycled material obtained from solid-liquid separation is mixed with the inferior heavy oil and catalyst to obtain a fourth mixed product; The fourth mixture is mixed with hydrogen to obtain the first mixture.

3. The method as described in claim 1, characterized in that, The first mixed product is subjected to a shallow hydrocracking reaction, including: The first mixed product was subjected to hydrocracking at a reaction temperature of 350-420℃ and a reaction pressure of 4-14 MPa. The hydrogen-to-oil volume ratio at the reactor inlet was 600-2000, the catalyst dosage per gram of low-quality heavy oil was 100-10000 μg, and the volume hourly space velocity (WHSV) was 0.5-2 h⁻¹. -1 The single-pass conversion rate is 30-60 wt%.

4. The method as described in claim 1, characterized in that, The first mixed product is subjected to a shallow hydrocracking reaction, including: The first mixed product was subjected to hydrocracking at a reaction temperature of 400-420℃ and a reaction pressure of 10-12 MPa. The hydrogen-to-oil volume ratio at the reactor inlet was 1000-1500, the catalyst dosage per gram of low-quality heavy oil was 100-5000 μg, and the volume hourly space velocity (HSV) was 1-1.5 h⁻¹. -1 The single-pass conversion rate is 40-50 wt%.

5. The method as described in claim 1, characterized in that, The amount of the composite flocculant added is 0.01-0.2% of the weight of the liquid product; The quaternary ammonium salt surfactant includes one or a combination of several of the following: dihexadecyl dimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, alkyl dimethyl ammonium chloride, and octadecyl trimethyl ammonium bromide; The organic polymeric flocculant includes one or a combination of several of the following: cationic polyacrylamide, sodium polyacrylate, polyvinylpyridine salt, and polyethyleneimine. The inorganic polymeric flocculant includes one or a combination of several of the following: polyaluminum ferric silicate, polyaluminum ferric sulfate, polyaluminum silicate, and polyaluminum ferric phosphate. The reverse oil-soluble demulsifier includes one or a combination of several of the following: polyether-based reverse oil-soluble demulsifiers, polyoxypropylene-based reverse oil-soluble demulsifiers, polyamide-based reverse oil-soluble demulsifiers, and polytriethanolamine-based reverse oil-soluble demulsifiers.

6. The method as described in claim 1, characterized in that, The amount of the composite flocculant added is 0.05-0.1% of the weight of the liquid product; The composite flocculant includes: dihexadecyldimethylammonium bromide, cationic polyacrylamide, polyaluminum ferric silicate, and polyether-based reverse oil-soluble demulsifier, with a weight ratio of 5-10:1-3:50-100:10-50.

7. The method as described in claim 1, characterized in that, Continuous deposition of the second mixture includes: using a continuous deposition apparatus, performing continuous deposition at a temperature of 100-200°C by liquid-liquid separation.

8. The method as described in claim 1, characterized in that, The inferior heavy oil includes one or a combination of several of the following: atmospheric residue, vacuum residue, deasphalted oil, oil sands asphalt, high-viscosity crude oil, coal tar, and coal liquefaction heavy oil.

9. The method as described in claim 1, characterized in that, The catalyst is a solid powder catalyst, a water-soluble catalyst, an oil-soluble catalyst, or a microemulsion catalyst.

10. The method as described in claim 1, characterized in that, The overflow material is subjected to hydrodesulfurization treatment, including: The overflow material is subjected to hydrodesulfurization treatment using one or more of the following: hydroprotective agent, hydrodemetallization catalyst, and hydrodesulfurization catalyst. The hydrodemetallization catalyst and the hydrodesulfurization catalyst contain an active metal and a support; the active metal contains at least one of Group VI metals and / or Group VIII metals; the support contains at least one of alumina, amorphous aluminum silica, and silicon dioxide.

11. The method as described in claim 2, characterized in that, The mass ratio of the underflow material to the aromatic-rich component is 1:1-10; The aromatic-rich components include one or more of catalytic diesel, catalytic slurry, and naphthenic crude oil.

12. The method as described in claim 2, characterized in that, Solid-liquid separation of the third mixed product includes: using a solid-liquid separation device to perform solid-liquid separation treatment at an operating temperature of 100-200°C.

13. The method according to any one of claims 1-12, characterized in that, This is achieved through a system for producing low-sulfur fuel oil, which includes: an enhanced hydrogen mixing unit, a slurry bed reactor, a gas-liquid separation unit, a continuous deposition unit, and a fixed bed reactor; The enhanced hydrogen mixing device is used to mix inferior heavy oil, catalyst and hydrogen to obtain a first mixed product; The slurry bed reactor is connected to the enhanced hydrogen mixing device and is used to perform a shallow hydrocracking reaction on the first mixed product. The gas-liquid separation device is connected to the slurry bed reactor and is used to separate the product obtained after shallow hydrocracking reaction into gas and liquid components. The continuous deposition device is connected to the gas-liquid separation device and is used to mix the liquid phase product after gas-liquid separation with the composite flocculant to obtain a second mixed product. The second mixed product is then continuously deposited to obtain overflow material and underflow material. The fixed-bed reactor is used to perform hydrodesulfurization treatment on the overflow material to produce low-sulfur fuel oil.

14. The method as described in claim 13, characterized in that, Also includes: Solid-liquid separation device and mixing device; The solid-liquid separation device is connected to the continuous deposition device and is used to mix the underflow material with aromatic hydrocarbon-rich components to obtain a third mixed product. The third mixture is subjected to solid-liquid separation; The mixing device is connected to the solid-liquid separation device and is used to mix the recycled material obtained from solid-liquid separation with the inferior heavy oil and catalyst to obtain a fourth mixed product. The enhanced hydrogen mixing device is also used to mix the fourth mixed product with hydrogen to obtain the first mixed product.

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