Method and device for preparing residue type low-sulfur fuel oil

Abstract

The invention provides a preparation method and device of residue type low-sulfur fuel oil, and belongs to the technical field of petroleum refining processes and equipment. The method comprises the following steps: firstly, carrying out electro-desalting and passivator atomization pretreatment on raw materials, and cooperatively inhibiting the formation of a coking precursor by combining light distillate oil dilution and a passivator; then, a graded hydrodesulfurization process is adopted, macromolecular sulfides are selectively cracked through a demetallization agent and the sulfur content is controlled to be 1.0-1.8 wt% through a Co-Mo catalyst in sequence under the mild condition, and the desulfurization depth and the cracking degree are balanced; the obtained oil product is subjected to sulfolane reinforced counter-current extraction to efficiently remove colloid-coated thiophene sulfide, finally, low-sulfur hydrogenation bypass light oil is dynamically doped based on real-time NIR detection, a viscosity reducer is added, and the sulfur content and viscosity of a final product are synchronously regulated and controlled. According to the method, the coking risk is reduced through staged hydrogenation-extraction cooperation, raw material fluctuation is adapted by means of a sulfur-viscous dynamic regulation mechanism, a repeated temperature adjustment link of a traditional process is eliminated, compared with a traditional hydrogenation process, the energy consumption is reduced by 18-22%, and the operation cycle of a device is remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum refining process and equipment, and particularly relates to a preparation method and device of residual low-sulfur fuel oil. BACKGROUND

[0002] Residual fuel oil is the end product of crude oil vacuum distillation, and its yield accounts for about 15%-30% of the total amount of crude oil processing. The component is rich in asphaltene, gum and heteroatomic compounds, and the typical sulfur content is 1.5%-4.0% (mass fraction), and the kinematic viscosity (50°C) is generally higher than 500 mm 2 / s. Under the framework of increasingly stringent environmental protection regulations, the application of traditional high-sulfur residual fuel oil is fundamentally restricted, and its sulfur content must be reduced to below 0.5% to meet the mainstream market access standards. This rigid requirement has prompted the oil refining industry to accelerate the development of an economically viable desulfurization technology route.

[0003] The existing industrialized technologies are mainly divided into two paths of physical separation and chemical conversion. The physical separation method is represented by the solvent deasphalting process, which selectively removes sulfur-containing macromolecules by dissolving them in light hydrocarbon solvents such as propane or butane. However, this method produces a by-product of deoiled asphalt accounting for 20%-30% of the raw material, which is difficult to effectively utilize due to its high softening point and heavy metal content. The conventional disposal method requires a delayed coking or asphalt gasification device, significantly increasing the system complexity and operating cost. The chemical conversion path focuses on hydroprocessing technology, which removes sulfur elements through catalytic hydrogenation under high pressure and high temperature (>380°C, >12 MPa) conditions. Although this method can achieve deep desulfurization, excessive cracking leads to a loss of light component yield, and the equipment investment intensity exceeds the bearing capacity of small and medium-sized refineries.

[0004] To balance the technical economy, the industry attempts to use a combination process of visbreaking and hydrofining. The visbreaking section makes macromolecular hydrocarbons thermally cracked to reduce viscosity at 380°C-420°C, but the high-temperature environment causes asphaltene condensation reactions, generating coke that deposits on the reactor wall and heat exchange surface. Industrial practice shows that such coking can reduce the heat transfer efficiency by more than 40% in three months, forcing the device to frequently shut down for decoking. The hydrofining section can remove part of the sulfides, but the removal rate of thiophene sulfides wrapped in the gum layer is less than 40%, making it difficult to meet the sulfur content of heavy components.

[0005] The deeper problem is the fragmentation of the existing process system. Desulfurization unit, viscosity adjustment unit and stabilization unit are usually set up independently, and the intermediate material needs to undergo repeated heating and cooling process. For example, in the conventional process, the hydrogenation reaction product needs to be cooled from 380℃ to 150℃ to enter the solvent extraction tower, and the raffinate phase after extraction is heated to 220℃ for blending. This temperature cycle not only increases the energy consumption by 15%-20%, but also causes pipeline fouling due to the dissolution-precipitation behavior of asphaltene under temperature fluctuation. At the same time, when the sulfur content of the raw material fluctuates (such as 1.0%-3.5%), a single process parameter setting cannot simultaneously guarantee the dual indicators of sulfur content ≤0.5% and kinematic viscosity ≤380 cSt (50℃) of the final product.

[0006] Based on the above analysis, the industry development of residual fuel oil urgently needs to break through three technical barriers: first, develop a mild desulfurization path to inhibit the coking tendency; second, establish a sulfur-viscosity coordinated control mechanism to cope with the fluctuation of raw material properties; third, reduce the switching of intermediate links through process integration. This requires that the innovative scheme must achieve coordinated optimization from the aspects of reaction engineering and equipment design, so as to achieve the unity of economy and environmental protection. SUMMARY

[0007] The purpose of the present application is to provide a preparation method and device of residual low-sulfur fuel oil, aiming at the problems of high cost, easy coking and sulfur-viscosity control mismatch in the production of residual fuel oil.

[0008] To achieve the above purpose, the present application provides the following technical scheme: a preparation method of residual low-sulfur fuel oil, comprising the following steps: Step one: metal removal and lightening pretreatment of raw material: vacuum residue is pumped into an electric desalting device for desalting treatment, and the desalted residue oil is injected into 0.01%-0.03% of organic tin passivator by an ultrasonic atomizing nozzle, the desalted and passivated residue oil is mixed with light distillate oil with a distillation range of 200-350℃ by a static mixer at a mass ratio of 83:17-87:13 to obtain a premixed raw material oil; Step two: variable-diameter staged hydrogenation desulfurization: the premixed raw material oil prepared in step one is pumped into a variable-diameter fixed bed reactor, the material is first contacted with a large-pore alumina metal removal agent in a large-diameter bed layer to control the metal impurity content at the outlet; then the material passes through a 7±0.5 conical transition section into a small-diameter bed layer to perform hydrogenation desulfurization reaction on a Co-Mo / Al2O3 catalyst to control the sulfur content at the outlet and the system pressure drop, and the reactor effluent is separated in a high-pressure separator to obtain top hydrogenation bypass light oil and bottom hydrogenation desulfurization raw material oil for storage; Step three: spin disk enhanced solvent extraction: the hydrogen desulfurization feedstock prepared in step two is put into a spin disk extraction tower, and three-stage countercurrent extraction is carried out with sulfolane as a solvent, the solvent to oil ratio is 1.2:1, the rotation speed of the tower tray is controlled in the range of 120±20 rpm, the operating temperature is maintained at 105±3℃, and the sulfur content of the raffinate phase is ensured to be ≤0.25wt%, and the raffinate phase oil product is obtained for standby; Step four: blending and self-cleaning: the raffinate phase oil product prepared in step three and 22-25wt% hydrogen bypass light oil prepared in step two are pumped into a blending system, the sulfur content of the mixed oil product is detected in real time, the proportion of light oil injection is dynamically adjusted, and 0.15±0.05% of ethylene-vinyl acetate copolymer viscosity reducer based on the mass of the final mixed oil product is injected; the product after blending is output through a double self-cleaning filter to prepare a residual low-sulfur fuel oil.

[0009] As a further scheme of the present application: the vacuum residue in step one has a sulfur content of 1.5-3.5wt%, a 50℃ kinematic viscosity of 800-1500cSt, a total amount of metals Ni+V≤300ppm, Ca 2+ / Na + ≤80ppm; the organic tin passivator is any one of dibutyl tin oxide, dibutyl tin dilaurate or the like, the desalting treatment is carried out under the conditions of 130±5℃ / 0.4±0.05MPa, an electric field of 3.5kV / cm is applied for 40±5min, and the residual Ca 2+ / Na + after desalting is controlled to be ≤15ppm.

[0010] As a further scheme of the present application: the large-diameter bed in step two has an inner diameter of Φ2.8m, a large-pore alumina demetallization agent is used, and the operating conditions are: temperature 342±5℃, pressure 6.8±0.2MPa, liquid hourly space velocity (LHSV) 0.8±0.1h -1 , and the total amount of Ni+V at the outlet is controlled to be ≤60ppm; the large-pore alumina demetallization agent is any one of BASF FDM-778, Albemarle ADM-740 or Clariant HDM-305, and meets the following physical and chemical indexes: specific surface area 320-350m 2 / g; pore volume 0.85-0.95cm 3 / g; most probable pore diameter 17-20nm; side pressure strength ≥35N / mm; The small-diameter bed has an inner diameter of Φ1.6m, a Co-Mo / Al2O3 catalyst is used, and the operating conditions are: temperature 350±5℃, pressure 7.0±0.2MPa, liquid hourly space velocity (LHSV) 1.2±0.05h -1 , the sulfur content at the outlet is controlled to be 1.0~1.8wt%, and the system pressure drop is ≤0.15MPa.

[0011] The utility model provides a preparation device of residue type low sulfur fuel oil, rotary disc extraction tower includes tower body, one side of tower body is connected with heavy liquid inlet and light liquid inlet fixedly, the other side of tower body is connected with light liquid outlet and heavy liquid outlet fixedly, the inner chamber of tower body is provided with upper grid and lower grid, light liquid outlet is located the top of upper grid, heavy liquid inlet is located the below of upper grid, light liquid inlet is located the top of lower grid, heavy liquid outlet is located the below of lower grid, the top of tower body is installed top plate, the top of top plate is installed motor, the inner chamber rotationally connected with rotating shaft of tower body is through upper grid and lower grid, the outer wall of rotating shaft is fixedly connected with rotary disc, the inner chamber of tower body is installed fixed plate between upper grid and lower grid, fixed plate and lower grid are positioned through positioning mechanism, top plate and upper grid are installed through mounting mechanism.

[0012] As a further aspect of the present application: the positioning mechanism includes a fixed ring, the fixed ring is fixedly connected to the inner wall of the tower body, the inner wall of the tower body is symmetrically provided with a vertical slot, the inner wall of the vertical slot is slidably connected with a vertical rod, the outer wall of the vertical rod is fixedly connected with a clamping block and a supporting block, the clamping block is located below the supporting block, the outer wall of the fixed plate is symmetrically fixedly connected with a connecting block, the outer wall of the connecting block is provided with a clamping groove, the outer wall of the vertical rod is provided with a connecting groove for inserting the connecting block, the top end of the vertical rod is rotatably connected with a rotating column, the bottom end of the rotating column is fixedly connected with a first threaded rod, the outer wall of the first threaded rod is slidably connected with a displacement block, the displacement block is slidably connected inside the vertical rod, the top end of the displacement block is fixedly connected with a clamping block, the clamping block is located below the connecting groove.

[0013] As a further scheme of the present application: the installation mechanism comprises a lower installation block, the lower installation block is symmetrically fixedly connected to the top of the tower body, a slot is formed in the outer wall of the lower installation block, the outer wall of the top plate is symmetrically fixedly connected with an upper installation block, the bottom end of the upper installation block is fixedly connected with an insertion block, the top end of the upper installation block is rotatably connected with a rotating block, the bottom end of the rotating block is fixedly connected with a second threaded rod, the outer wall of the second threaded rod is slidably connected with a sliding block, the sliding block is slidably connected in the interiors of the upper installation block and the insertion block, the bottom end of the sliding block is rotatably connected with a connecting rod, the bottom end of the connecting rod is rotatably connected with a fixed block, the fixed block is slidably connected in the interior of the insertion block and extends out of the insertion block, the output end of the motor is connected with a butt joint block, a square groove is formed in the bottom end of the butt joint block, the top end of the rotating shaft is fixedly connected with a square block, a positioning block is slidably connected in the interior of the tower body and extends into the inner cavity of the tower body, springs are connected between the positioning block and the tower body, a pressing rod is slidably connected in the interior of the tower body above the positioning block, and the pressing rod extends above the tower body.

[0014] As a further scheme of the present application: the outer wall of the connecting block is matched with the inner wall of the connecting slot, and the outer wall of the displacement block is provided with a first threaded hole matched with the first threaded rod.

[0015] As a further scheme of the present application: the outer wall of the clamping block is matched with the inner wall of the clamping slot, and the outer wall of the vertical rod is matched with the inner wall of the vertical slot.

[0016] As a further scheme of the present application: the inner wall of the slot is matched with the outer wall of the insertion block, the top end of the sliding block is provided with a second threaded hole matched with the second threaded rod, and the inner wall of the square groove is matched with the outer wall of the square block.

[0017] As a further scheme of the present application: the top end of the positioning block is provided with an inclined surface, and the bottom end of the pressing rod is in contact with the inclined surface.

[0018] Compared with the prior art, the present application has the following advantages: 1. The preparation method of the residue type low-sulfur fuel oil adopts a hierarchical hydrogenation and solvent extraction synergistic process to realize deep desulfurization under mild conditions: the front-stage metal removal reaction selectively cracks macromolecular sulfides, the rear-stage hydrogenation precisely controls the sulfur content to 1.0-1.8wt%, and then the rotating disc is used for reinforced countercurrent extraction to efficiently remove thiophene sulfur wrapped by colloid, the sulfur content of the raffinate phase is stably ≤0.25wt%, the coking tendency is significantly reduced in the whole process, and the continuous operation period of the device is significantly prolonged. 2. The preparation method of the residue type low-sulfur fuel oil is based on real-time online blending of hydrogen bypass light oil (sulfur content is less than or equal to 0.15wt%) and raffinate phase oil, the light oil blending ratio (22wt%-25wt%) and the amount of viscosity reducer added are dynamically adjusted through the embedded NIR probe, and the sulfur content of the final product is reduced to less than or equal to 0.50wt%, and the 40 DEG C viscosity is controlled to less than or equal to 380cSt, so that the double-index limit value is met at one time, the repeated temperature adjustment and intermediate cooling link of the traditional process are avoided, and the comprehensive energy consumption is reduced by 18%-22%; 3. By setting the positioning mechanism and the mounting mechanism, the top plate is disassembled, the positioning block is separated from the upper grid plate under the action of the spring elastic force, the fixing of the upper grid plate is cancelled, the upper grid plate can be taken out from the tower body, then the rotating shaft is taken out from the tower body, the sliding vertical rod is moved out from the vertical groove, the disassembly of the fixed plate is completed, after the completion, the lower grid plate is taken out from the tower body, the parts in the tower body can be quickly disassembled, so that the tower body can be conveniently cleaned, and the solution is prevented from remaining between the fixed plate and the tower body during the washing of the tower body. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The process flow chart for preparing the fraction type fuel oil from the waste mineral oil is shown in the figure; Figure 2 The structure diagram of the tower body is shown in the figure; Figure 3 The sectional view of the tower body is shown in the figure; Figure 4 The installation diagram of the vertical rod is shown in the figure; Figure 5 The sectional view of the vertical rod is shown in the figure; Figure 6 The installation diagram of the top plate is shown in the figure; Figure 5 The enlarged view of A in the figure; Figure 7 The installation diagram of the top plate is shown in the figure; Figure 8 The enlarged view of B in the figure; Figure 7 The enlarged view of B in the figure; Figure 9 The sectional view of the top plate is shown in the figure.

[0020] In the figure: 1, tower body; 2, heavy liquid inlet; 3, light liquid inlet; 4, light liquid outlet; 5, heavy liquid outlet; 6, upper grid plate; 7, lower grid plate; 8, positioning mechanism; 801, fixed ring; 802, vertical groove; 803, vertical rod; 804, clamping block; 805, supporting block; 806, connecting block; 807, clamping groove; 808, connecting groove; 809, rotating column; 810, first threaded rod; 811, displacement block; 812, clamping block; 9, mounting mechanism; 901, lower mounting block; 902, insertion groove; 903, upper mounting block; 904, insertion block; 905, rotating block; 906, second threaded rod; 907, sliding block; 908, connecting rod; 909, fixed block; 910, butt joint block; 911, square groove; 912, square block; 913, positioning block; 914, spring; 915, extrusion rod; 10, fixed plate; 11, motor; 12, rotating shaft; 13, rotating disc; 14, top plate. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0022] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "setting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. The embodiments of the present application will be described below according to the overall structure of the present application. Embodiment 1

[0023] Please refer to Figures 1 to 7 In the embodiments of the present application, a preparation method of a residue type low-sulfur fuel oil comprises the following steps: Step one, removal of raw material metal and light weight pretreatment The vacuum residue with sulfur content of 2.5wt%, kinematic viscosity of 1200cSt at 50℃, total metal content (Ni+V) of 220ppm, Ca 2+ / Na + 65ppm was pumped into an electric desalting device, and treated under the condition of 3.5kV / cm electric field at 132℃ / 0.41MPa for 42min, with the control of Ca 2+ / Na + 11ppm after desalting. The desalted residue was injected into an ultrasonic atomizing nozzle with 0.02% of dibutyltin dilaurate as a passivator by mass, and the desalted and passivated residue was mixed with light distillate oil of 200-350℃ distillation range in a static mixer at a mass ratio of 85:15, to obtain the pre-mixed feedstock oil.

[0024] Step two, variable diameter staged hydrodesulfurization The pre-mixed feedstock oil was pumped into a variable diameter fixed bed reactor, and the material was contacted with Albemarle ADM-740 large-pore alumina metal removal agent in a Φ2.8m bed at 340℃ / 6.75MPa / liquid hourly space velocity of 0.82h -1 , with the control of total Ni+V content of 48ppm at the outlet; then the material entered a Φ1.6m bed through a 7° conical section, and reacted on a Co-Mo / Al2O3 catalyst at 348℃ / 7.05MPa / liquid hourly space velocity of 1.18h -1 , with the control of sulfur content of 1.3wt% at the outlet and system pressure drop of 0.12MPa; the reactor effluent was separated in a high-pressure separator at 195℃ / 4.95MPa, to obtain hydrogenated bypass light oil (distillation range 200-300℃) with sulfur content of 0.15wt% and hydrogenated desulfurized feedstock oil.

[0025] Step three, rotating disc enhanced solvent extraction The hydrogenated desulfurized feedstock oil was passed into a rotating disc extraction column, and three-stage countercurrent extraction was carried out with sulfolane as the solvent at a solvent to oil ratio of 1.2:1, with the control of disc rotation speed of 125rpm and operating temperature of 104℃, to ensure the sulfur content of 0.21wt% in the raffinate phase, and to obtain the raffinate phase oil for standby use.

[0026] Step four, online intelligent blending and self-cleaning The residual phase oil product is pumped into a blending system with 23wt% hydrogenated bypass light oil, the sulfur content of the mixed oil product is detected in real time by an embedded NIR probe, the proportion of light oil injection is dynamically adjusted, and 0.15% of the final mixed oil product is injected into the ethylene-vinyl acetate copolymer viscosity reducer; the product after blending is output through a double self-cleaning filter, a 0.5MPa light oil pulse backflush is triggered (execution time 1.8 seconds), and finally a residual low-sulfur fuel oil with a sulfur content of 0.42wt% and a viscosity of 365cSt at 50°C is obtained. (Due to the partial dissociation of residual sulfides in the gum component during the blending process, the actual final product sulfur content is slightly higher than the theoretical calculated value).

[0027] In this embodiment: the preparation method of the residual low-sulfur fuel oil of the present application adopts a staged hydrogenation and solvent extraction cooperative process to achieve deep desulfurization under mild conditions: the front-stage demetallization reaction selectively cracks macromolecular sulfides, the rear-stage hydrogenation precisely controls the sulfur content to 1.0~1.8wt%, and then the thiofuran sulfur wrapped by gum is efficiently removed through a rotating disc enhanced countercurrent extraction, the sulfur content of the residual phase is stably ≤0.25wt%, the coking tendency is significantly reduced throughout the process, and the continuous operation cycle of the device is significantly prolonged; The preparation method of the residual low-sulfur fuel oil of the present application is based on real-time online blending of hydrogenated bypass light oil (sulfur content ≤0.15wt%) and residual phase oil product, dynamically adjusting the light oil blending ratio (22~25wt%) and the amount of viscosity reducer added through an embedded NIR probe, simultaneously reducing the sulfur content of the final product to ≤0.50wt% and controlling the viscosity at 40°C to ≤380cSt, one-time meeting the dual-index limit, avoiding repeated temperature adjustment and intermediate cooling steps in traditional processes, and reducing overall energy consumption by 18~22%.

[0028] A residual low-sulfur fuel oil preparation device, the rotating disc extraction tower comprises a tower body 1, one side of the tower body 1 is fixedly connected with a heavy liquid inlet 2 and a light liquid inlet 3, the other side of the tower body 1 is fixedly connected with a light liquid outlet 4 and a heavy liquid outlet 5, an inner cavity of the tower body 1 is provided with an upper grid plate 6 and a lower grid plate 7, the light liquid outlet 4 is located above the upper grid plate 6, the heavy liquid inlet 2 is located below the upper grid plate 6, the light liquid inlet 3 is located above the lower grid plate 7, and the heavy liquid outlet 5 is located below the lower grid plate 7, a top plate 14 is installed at the top end of the tower body 1, a motor 11 is installed at the top end of the top plate 14, a rotating shaft 12 penetrating through the upper grid plate 6 and the lower grid plate 7 is rotationally connected in the inner cavity of the tower body 1, the rotating shaft 12 is fixedly connected with a rotating disc 13, a fixed plate 10 is installed between the upper grid plate 6 and the lower grid plate 7 in the inner cavity of the tower body 1, the fixed plate 10 and the lower grid plate 7 are positioned through a positioning mechanism 8, and the top plate 14 and the upper grid plate 6 are installed through an installation mechanism 9.

[0029] In the embodiment, the light liquid enters the tower body 1 through the light liquid inlet 3 and is discharged from the light liquid outlet 4, the heavy liquid enters the tower body 1 through the heavy liquid inlet 2 and is discharged from the heavy liquid outlet 5, and the motor 11 drives the rotating shaft 12 to rotate, and the rotating shaft 12 drives the rotating disc 13 to rotate, so that the liquid is fully contacted.

[0030] Please refer to Figures 2 to 5 The positioning mechanism 8 comprises a fixed ring 801 fixedly connected to the inner wall of the tower body 1, the inner wall of the tower body 1 is symmetrically provided with a vertical groove 802, the inner wall of the vertical groove 802 is slidably connected with a vertical rod 803, the outer wall of the vertical rod 803 is fixedly connected with a clamping block 804 and a supporting block 805, the clamping block 804 is located below the supporting block 805, the outer wall of the fixed plate 10 is symmetrically fixedly connected with a connecting block 806, the outer wall of the connecting block 806 is provided with a clamping groove 807, the outer wall of the vertical rod 803 is provided with a connecting groove 808 for inserting the connecting block 806, the top end of the vertical rod 803 is rotatably connected with a rotating column 809, the bottom end of the rotating column 809 is fixedly connected with a first threaded rod 810, the outer wall of the first threaded rod 810 is slidably connected with a displacement block 811, the displacement block 811 is slidably connected in the vertical rod 803, the top end of the displacement block 811 is fixedly connected with a clamping block 812, and the clamping block 812 is located below the connecting groove 808.

[0031] In the embodiment, when the lower lattice plate 7 and the fixed plate 10 are installed, the lower lattice plate 7 is placed into the inner cavity of the tower body 1, and the bottom end of the lower lattice plate 7 is in contact with the fixed ring 801; then the vertical rod 803 is installed on both sides of the fixed plate 10, the connecting block 806 is inserted into the connecting groove 808, then the rotating column 809 is rotated, the rotating column 809 drives the first threaded rod 810 to rotate, the first threaded rod 810 drives the displacement block 811 to displace, the displacement block 811 drives the clamping block 812 to displace, and the clamping block 812 is inserted into the clamping groove 807 to fix the vertical rod 803 and the fixed plate 10; then the vertical rod 803 is connected into the vertical groove 802, at this time, the clamping block 804 is in contact with the top end of the lower lattice plate 7, so that the position of the lower lattice plate 7 is positioned, and the lower lattice plate 7 and the fixed plate 10 are positioned. After the lower lattice plate 7 and the fixed plate 10 are positioned, the rotating shaft 12 is connected into the inner cavity of the tower body 1, and the rotating shaft 12 penetrates the lower lattice plate 7, then the upper lattice plate 6 is connected into the inner cavity of the tower body 1, and the bottom end of the upper lattice plate 6 is in contact with the supporting block 805.

[0032] Please refer to Figures 6 to 8The mounting mechanism 9 comprises a lower mounting block 901 symmetrically fixedly connected to the top of the tower body 1, the outer wall of the lower mounting block 901 is provided with a slot 902, the outer wall of the top plate 14 is symmetrically fixedly connected with an upper mounting block 903, the bottom end of the upper mounting block 903 is fixedly connected with a plug block 904, the top end of the upper mounting block 903 is rotatably connected with a rotating block 905, the bottom end of the rotating block 905 is fixedly connected with a second threaded rod 906, the outer wall of the second threaded rod 906 is slidably connected with a sliding block 907, the sliding block 907 is slidably connected in the interiors of the upper mounting block 903 and the plug block 904, the bottom end of the sliding block 907 is rotatably connected with a connecting rod 908, the bottom end of the connecting rod 908 is rotatably connected with a fixed block 909, the fixed block 909 is slidably connected in the interior of the plug block 904 and extends out of the plug block 904, the output end of the motor 11 is connected with a butt joint block 910, the bottom end of the butt joint block 910 is provided with a square slot 911, the top end of the rotating shaft 12 is fixedly connected with a square block 912, the interior of the tower body 1 is slidably connected with a positioning block 913 extending into the inner cavity of the tower body 1, the positioning block 913 is connected with a spring 914 between the tower body 1, the interior of the tower body 1 is slidably connected with an extrusion rod 915 above the positioning block 913, the extrusion rod 915 extends above the tower body 1.

[0033] In the embodiment, when the top plate 14 is installed, the plug block 904 is inserted into the slot 902, then the rotating block 905 is rotated, the rotating block 905 drives the second threaded rod 906 to rotate, the second threaded rod 906 drives the sliding block 907 to displace, the sliding block 907 drives the fixed block 909 to displace through the connecting rod 908, the fixed block 909 displaces to make the plug block 904 contact the bottom end of the lower mounting block 901, so as to fix the top plate 14; at this time, the square block 912 is inserted into the square slot 911, so that the motor 11 drives the butt joint block 910 to rotate when the motor 11 operates, the butt joint block 910 drives the rotating shaft 12 to rotate through the square block 912; In the process that the top plate 14 contacts the tower body 1, the top plate 14 contacts the extrusion rod 915, the extrusion rod 915 is pushed to displace, the extrusion rod 915 drives the positioning block 913 to displace, the spring 914 is extruded, the positioning block 913 displaces to enter the inner cavity of the tower body 1 and contact the top end of the upper lattice plate 6, so as to automatically fix the upper lattice plate 6, which is convenient for fixing and installing the top plate 14 and the upper lattice plate 6; When the parts in the tower body 1 are disassembled, the top plate 14 is removed, at this time the positioning block 913 is separated from the upper grid plate 6 under the elastic force of the spring 914, the fixing of the upper grid plate 6 is cancelled, at this time the upper grid plate 6 can be taken out from the tower body 1, then the rotating shaft 12 is taken out from the tower body 1, the sliding vertical rod 803 is removed from the vertical slot 802, the disassembly of the fixed plate 10 is completed, and after the completion, the lower grid plate 7 is taken out from the tower body 1, so that the parts in the tower body 1 can be quickly disassembled, thereby facilitating the cleaning operation of the tower body 1, and avoiding that when the tower body 1 is washed, the solution is difficult to be cleaned because it is left between the fixed plate 10 and the tower body 1.

[0034] Please refer to Figures 2 to 5 The outer wall of the connecting block 806 is matched with the inner wall of the connecting groove 808, and the outer wall of the displacement block 811 is provided with a first threaded hole matched with the first threaded rod 810.

[0035] In this embodiment, the connecting block 806 is inserted into the connecting groove 808, then the rotating column 809 is rotated, the rotating column 809 drives the first threaded rod 810 to rotate, and the first threaded rod 810 drives the displacement block 811 to displace.

[0036] Please refer to Figures 2 to 5 The outer wall of the clamping block 812 is matched with the inner wall of the clamping groove 807, and the outer wall of the vertical rod 803 is matched with the inner wall of the vertical slot 802.

[0037] In this embodiment, the displacement of the displacement block 811 drives the clamping block 812 to displace, the clamping block 812 is inserted into the clamping groove 807 to fix the vertical rod 803 and the fixed plate 10, then the vertical rod 803 is connected into the vertical slot 802.

[0038] Please refer to Figures 6 to 8 The inner wall of the insertion groove 902 is matched with the outer wall of the insertion block 904, the top end of the sliding block 907 is provided with a second threaded hole matched with the second threaded rod 906, and the inner wall of the square groove 911 is matched with the outer wall of the square block 912.

[0039] In this embodiment, the insertion block 904 is inserted into the insertion groove 902, then the rotating block 905 is rotated, the rotating block 905 drives the second threaded rod 906 to rotate, the second threaded rod 906 drives the sliding block 907 to displace, the sliding block 907 drives the fixed block 909 to displace through the connecting rod 908, the fixed block 909 is in contact with the bottom end of the lower mounting block 901, so as to fix the top plate 14, at this time the square block 912 is inserted into the square groove 911, so that the motor 11 drives the abutting block 910 to rotate when the motor 11 operates, and the abutting block 910 drives the rotating shaft 12 to rotate through the square block 912.

[0040] Please pay attention to Figures 6 to 8 The top end of the positioning block 913 is provided with an inclined surface, and the bottom end of the extrusion rod 915 is in contact with the inclined surface.

[0041] In this embodiment: in the process of the top plate 14 contacting the tower body 1, the top plate 14 contacts the extrusion rod 915, pushes the extrusion rod 915 to displace, the extrusion rod 915 displaces to push the positioning block 913 to displace, and the positioning block 913 displaces into the inner cavity of the tower body 1 and contacts the top end of the upper grid plate 6. Example 2

[0042] Step one: vacuum residue with sulfur content of 3.5wt%, viscosity of 1450cSt, and Ni+V of 290ppm, after electric desalting, residual Ca 2 + / Na + 14ppm, 0.03% dibutyl tin oxide is injected, and the mixture ratio is 83:17.

[0043] Step two: demetallization outlet Ni+V of 57ppm; hydrogenation outlet sulfur content of 1.8wt% (pressure drop of 0.15MPa); hydrogenation bypass light oil sulfur content of 0.14wt%.

[0044] Step three: tray rotation speed of 140rpm, raffinate phase sulfur content of 0.25wt%.

[0045] Step four: dynamic blending of 25wt% hydrogenation bypass light oil, final product sulfur content of 0.50wt%, viscosity of 380cSt.

[0046] The rest is the same as example 1, which will not be repeated here. Example 3

[0047] Step one: sulfur content of 1.5wt%, viscosity of 850cSt, Ni+V of 180ppm, after electric desalting, residual Ca 2+ / Na + 9ppm, 0.01% dibutyltin dilaurate is injected, and the mixture ratio is 87:13.

[0048] Step two: demetallization outlet Ni+V of 35ppm; hydrogenation outlet sulfur content of 1.0wt% (pressure drop of 0.08MPa); hydrogenation bypass light oil sulfur content of 0.10wt%.

[0049] Step three: tray rotation speed of 100rpm, raffinate phase sulfur content of 0.18wt%.

[0050] Step four: blending of 22wt% hydrogenation bypass light oil, final product sulfur content of 0.38wt%, viscosity of 345cSt.

[0051] The rest is the same as Example 1, which will not be repeated here.

[0052] Comparative Example 1 Traditional single-stage hydrogenation Step two replacement: premixed raw oil into a single Φ2.8m Co-Mo / Al2O3 bed (375℃ / 12.0MPa / LHSV 0.6h -1 ), the outlet sulfur content is 1.6wt%, and the pressure drop is 0.35MPa after 48h.

[0053] Step three replacement: fixed bed extraction column (sulfolane, solvent oil ratio 1.5:1, static operation), the raffinate phase sulfur content is 0.43wt%.

[0054] Step four replacement: fixed blending 20wt% light distillate oil, the final product sulfur content is 0.71wt%, and the viscosity is 310cSt.

[0055] It is calculated that the comprehensive energy consumption of traditional single-stage hydrogenation process is 1.05GJ / t.

[0056] The rest is the same as Example 1, which will not be repeated here.

[0057] Comparative Example 2 Without passivator Step one replacement: the desalted residual oil is not added with passivator, and is directly mixed with light distillate oil.

[0058] Step two: the Ni+V of demetallization outlet is 198ppm; the sulfur removal rate of hydrogenation bed decreases by 22% after 48h, and the outlet sulfur content is 2.1wt%.

[0059] Step four: the final product sulfur content is 0.65wt%, and the viscosity is 420cSt.

[0060] The rest is the same as Example 1, which will not be repeated here.

[0061] Performance test The fuel oil prepared in Examples 1-3 and Comparative Examples 1-2 is tested for sulfur content, 50℃ kinematic viscosity, carbon residue value, metal removal rate and device pressure drop: The sulfur content is determined according to ASTM D4294; The kinematic viscosity is determined according to ASTM D445; The carbon residue value is determined according to ASTM D4530; The hydrogenation metal removal rate is calculated according to ASTM D5708 (raw material metal content-hydrogenation outlet metal content) / raw material metal content×100%; The device pressure drop is the value of 48h operation of the staged hydrogenation system.

[0062] The test results are shown in Table 1 below: Table 1 Comparison of key performance indicators of residual low-sulfur fuel oil

[0063] In summary, the present application successfully solves the problems of high-pressure coking, sulfur viscosity mismatch and high energy consumption in the production of residual fuel oil by four-in-one technical innovation of synergistic inhibition of coking by passivator-light fraction, deep desulfurization by variable-diameter staged hydrogenation, removal of gum sulfur by rotary disc intensified countercurrent extraction, and online dynamic regulation of sulfur-viscosity, realizes stable sulfur content ≤0.50wt% (adaptation to raw material sulfur content 1.5-3.5wt% fluctuation), precise control of viscosity to 345-380cSt (100% compliance rate), device pressure drop maintained at ≤0.15MPa (66% lower than traditional process), while the comprehensive energy consumption is reduced to 0.82-0.86GJ / t (18~22% lower than traditional process 1.05GJ / t), providing a high economic solution for the clean conversion of refinery heavy residual oil.

[0064] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical scheme and inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for preparing residual low-sulfur fuel oil, characterized in that The following steps are involved: Step 1: Pretreatment of the raw material for metal removal and lightening: The vacuum residue is pumped into an electrical desalter for desalination. An organotin passivating agent (0.01% to 0.03% by weight) is injected into the desalted residue through an ultrasonic atomizing nozzle. The desalted and passivated residue is then mixed with a light distillate oil with a distillation range of 200-350°C in a static mixer at a mass ratio of 83:17 to 87:13 to obtain a premixed raw material. Step 2: Variable Diameter Staged Hydrodesulfurization: The premixed feedstock produced in Step 1 is pumped into a variable diameter fixed-bed reactor. The material first reacts with a macroporous alumina demetallizer in the large-diameter bed to control the metallic impurity content at the outlet. The material then passes through a 7±0.5° tapered transition section into the small-diameter bed, where it undergoes hydrodesulfurization over a Co-Mo / Al2O3 catalyst to control the outlet sulfur content and system pressure drop. The reactor effluent enters a high-pressure separator for separation, yielding overhead hydrodesulfurization bypass light oil and bottom hydrodesulfurization feedstock, which are stored for future use. Step 3, Rotating Disc Enhanced Solvent Extraction: The hydrodesulfurized feedstock oil obtained in Step 2 is passed into a rotary disc extraction tower, and sulfolane is used as a solvent. A three-stage countercurrent extraction is performed at a solvent-to-oil ratio of 1.2:

1. The tray speed is controlled within the range of 120±20 rpm, and the operating temperature is maintained at 105±3°C. The sulfur content of the raffinate phase after the three-stage countercurrent extraction is ≤0.25wt%, and the raffinate phase oil product is obtained for later use; Step 4, blending and self-cleaning: The raffinate phase oil obtained in step 3 and the 22-25wt% hydrogenation bypass light oil prepared in step 2 are pumped into the blending system. By real-time detection of the sulfur content of the mixed oil, the injection ratio of the hydrogenation bypass light oil is dynamically adjusted, and an ethylene-vinyl acetate copolymer viscosity reducer accounting for 0.15±0.05% of the mass of the final mixed oil is injected; the blended product is output through a double self-cleaning filter to obtain residual low-sulfur fuel oil.

2. A method for preparing residual low-sulfur fuel oil according to claim 1, characterized in that: The vacuum residue oil of step 1 has a sulfur content of 1.5-3.5wt%, a kinematic viscosity of 800-1500cSt at 50°C, a total metal content (Ni+V) ≤300ppm, and a Ca 2+ / Na + ≤80ppm; the organic tin passivator is any one of dibutyltin oxide and dibutyltin dilaurate, wherein the desalination treatment is performed under the conditions of 130±5℃ / 0.4±0.05MPa with an electric field of 3.5kV / cm for 40±5min, and the residual Ca²⁺ / Na⁺ after desalination is controlled to be ≤15ppm.

3. A method for preparing residual low-sulfur fuel oil according to claim 1, characterized in that: The inner diameter of the large-diameter bed in step 2 is Φ2.8m, and a macroporous alumina demetallization agent is used. The operating conditions are: temperature 342±5℃, pressure 6.8±0.2MPa, liquid hourly space velocity (LHSV) 0.8±0.1h -1 , controlling the total amount of Ni+V at the outlet to ≤60ppm; the macroporous alumina demetallizing agent is selected from any one of BASF FDM-778, Albemarle ADM-740 or Clariant HDM-305; The inner diameter of the small-diameter bed is Φ1.6m, and the catalyst used is Co-Mo / Al2O3. The operating conditions are: temperature 350±5℃, pressure 7.0±0.2MPa, liquid hourly space velocity (LHSV) 1.2±0.05h -1 , control the outlet sulfur content to 1.0~1.8wt% and the system pressure drop ≤ 0.15MPa.

4. The preparation device of the method for preparing residual low-sulfur fuel oil according to any one of claims 1 to 3, characterized in that: The rotary disc extraction tower comprises a tower body (1), one side of the tower body (1) is fixedly connected with a heavy liquid inlet (2) and a light liquid inlet (3), the other side of the tower body (1) is fixedly connected with a light liquid outlet (4) and a heavy liquid outlet (5), the inner cavity of the tower body (1) is provided with an upper grid plate (6) and a lower grid plate (7), the light liquid outlet (4) is located above the upper grid plate (6), the heavy liquid inlet (2) is located below the upper grid plate (6), the light liquid inlet (3) is located above the lower grid plate (7), the heavy liquid outlet (5) is located below the lower grid plate (7), and the tower body (1) is fixedly connected with a heavy liquid inlet (2) and a light liquid outlet (5). A top plate (14) is installed at the top of the tower body (1), a motor (11) is installed at the top of the top plate (14), the inner cavity of the tower body (1) is rotatably connected to a rotating shaft (12) that passes through the upper lattice plate (6) and the lower lattice plate (7), the outer wall of the rotating shaft (12) is fixedly connected to a turntable (13), the inner cavity of the tower body (1) is located between the upper lattice plate (6) and the lower lattice plate (7), a fixed plate (10) is installed, the fixed plate (10) and the lower lattice plate (7) are positioned by a positioning mechanism (8), and the top plate (14) and the upper lattice plate (6) are installed by an installation mechanism (9).

5. The preparation device of the method for preparing residual low-sulfur fuel oil according to claim 4, characterized in that: The positioning mechanism (8) includes a fixing ring (801), the fixing ring (801) is fixedly connected to the inner wall of the tower body (1), the inner wall of the tower body (1) is symmetrically provided with vertical slots (802), the inner wall of the vertical slot (802) is slidably connected to a vertical rod (803), the outer wall of the vertical rod (803) is fixedly connected to a clamping block (804) and a support block (805), the clamping block (804) is located below the support block (805), the outer wall of the fixing plate (10) is symmetrically fixedly connected to a connecting block (806), the outer wall of the connecting block (806) is provided with a clamping slot (80 7), the outer wall of the vertical rod (803) is provided with a connecting groove (808) for inserting the connecting block (806), the top end of the vertical rod (803) is rotatably connected to a rotating column (809), the bottom end of the rotating column (809) is fixedly connected to a first threaded rod (810), the outer wall of the first threaded rod (810) is slidably connected to a displacement block (811), the displacement block (811) is slidably connected to the inside of the vertical rod (803), the top end of the displacement block (811) is fixedly connected to a clamping block (812), and the clamping block (812) is located below the connecting groove (808).

6. The preparation device of the method for preparing residual low-sulfur fuel oil according to claim 5, characterized in that: The mounting mechanism (9) comprises a lower mounting block (901), the lower mounting block (901) is symmetrically fixedly connected to the top of the tower body (1), a slot (902) is provided on the outer wall of the lower mounting block (901), an upper mounting block (903) is symmetrically fixedly connected to the outer wall of the top plate (14), an insert block (904) is fixedly connected to the bottom end of the upper mounting block (903), a rotating block (905) is rotatably connected to the top end of the upper mounting block (903), a second threaded rod (906) is fixedly connected to the bottom end of the rotating block (905), a slider (907) is slidably connected to the outer wall of the second threaded rod (906), the slider (907) is slidably connected to the interior of the upper mounting block (903) and the insert block (904), and the bottom end of the slider (907) is rotatably connected to the connecting rod (90 8), the bottom end of the connecting rod (908) is rotatably connected to a fixed block (909), the fixed block (909) is slidably connected to the inside of the plug block (904) and extends out of the plug block (904), the output end of the motor (11) is connected to a docking block (910), the bottom end of the docking block (910) is provided with a square groove (911), the top end of the rotating shaft (12) is fixedly connected to a square block (912), the interior of the tower body (1) is slidably connected to a positioning block (913) extending to the inner cavity of the tower body (1), a spring (914) is connected between the positioning block (913) and the tower body (1), the interior of the tower body (1) is located above the positioning block (913) and is slidably connected to an extrusion rod (915), and the extrusion rod (915) extends to the top of the tower body (1).

7. The preparation device of the method for preparing residual low-sulfur fuel oil according to claim 5, characterized in that: The outer wall of the connecting block (806) fits in contact with the inner wall of the connecting groove (808), and the outer wall of the displacement block (811) is provided with a first threaded hole, which matches the first threaded rod (810).

8. The preparation device of the method for preparing residual low-sulfur fuel oil according to claim 5, characterized in that: The outer wall of the clamping block (812) fits in contact with the inner wall of the clamping slot (807), and the outer wall of the vertical rod (803) fits in contact with the inner wall of the vertical slot (802).

9. The preparation device of the method for preparing residual low-sulfur fuel oil according to claim 6, characterized in that: The inner wall of the slot (902) fits with the outer wall of the insert block (904), a second threaded hole is provided at the top of the slider (907), the second threaded hole matches the second threaded rod (906), and the inner wall of the square slot (911) fits with the outer wall of the square block (912).

10. The preparation device of the method for preparing residual low-sulfur fuel oil according to claim 6, characterized in that: The top end of the positioning block (913) is provided with an inclined surface, and the bottom end of the extrusion rod (915) is in contact with the inclined surface.

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