A process and apparatus for the production of a low sulphur marine fuel oil

Abstract

The application provides a production method and device of low-sulfur marine fuel oil, in which a first bubble breaking unit breaks raw material hydrogen into micro-bubbles, which can effectively increase the phase boundary area of hydrogen and raw material heavy oil, enhance the hydrogen dissolving process, thereby enhancing the hydrogenation reaction process, reducing the reaction pressure, reducing the equipment investment and improving the hydrogen utilization rate; a second separation unit can effectively remove H2S gas in the first gas phase product generated in the slurry bed reactor, avoids the hindering of the H2S gas to the second hydrogenation reaction of the fixed bed reactor, and improves the product quality; in addition, the first reaction product from the slurry bed reactor is separated to obtain light distillate products and first heavy distillate, which are respectively introduced into the fixed bed reactor for hydrogenation refining, thereby avoiding the rapid deactivation of the catalyst at the front end of the fixed bed reactor and prolonging the operation cycle of the equipment.

Description

Technical Field

[0001] This invention relates to a method and apparatus for producing low-sulfur marine fuel oil. Background Technology

[0002] To address global environmental issues, the International Maritime Organization (IMO) has imposed stringent regulations on the sulfur content of marine fuel oil. For general maritime navigation, the sulfur content of marine fuel oil must not exceed 0.5%, and in some emission control areas, it is even required to be no higher than 0.1%. Currently, low-sulfur marine fuel oil is mainly produced by blending low-sulfur feedstocks after simple distillation. However, due to the scarcity of low-sulfur feedstock resources and the current trend towards heavier and lower-quality petroleum resources, the proportion of high-sulfur feedstocks is gradually increasing. Therefore, how to produce marine fuel oil using high-sulfur feedstocks is a pressing issue. The main method for producing marine fuel oil from high-sulfur feedstocks is residue hydrotreating. Existing residue hydrotreating technologies include fixed-bed, fluidized-bed, and slurry-bed hydrotreating. Two existing technologies for low-sulfur marine fuel oil production are described below:

[0003] Patent CN 113122332 A (published on July 16, 2021) discloses a method for producing low-sulfur marine fuel oil. Specifically, inferior heavy oil feedstock enters a pretreatment reactor and reacts with a pretreatment agent packed within the reactor. The reaction effluent is separated to obtain a first liquid phase, which is then mixed with hydrogen feedstock and enters a hydrogenation reaction zone. The hydrogenation reaction product is fractionated at atmospheric pressure to obtain light and heavy fractions. The heavy fraction is divided into two streams: one stream is used to produce 180# marine fuel oil, and the other stream is fractionated under reduced pressure to obtain reduced pressure distillate and tail oil. The light fraction and tail oil are mixed to obtain 360# marine fuel oil. This method requires the hydrogenation reaction zone to operate under relatively high pressure, making the reaction conditions relatively harsh. Furthermore, this method has a certain degree of adaptability to the properties of the feedstock.

[0004] Patent CN 113046125 A (published on June 29, 2021) discloses a method for producing gasoline and low-sulfur marine fuel. Specifically, residual oil feedstock undergoes a single hydrotreating process using both a fluidized bed hydrotreating reactor and a fixed bed hydrotreating reactor to obtain hydrotreating products. These products are then subjected to gas-liquid separation. The resulting liquid phase is not fractionated; a portion is used as low-sulfur marine fuel oil, and the remainder is subjected to catalytic cracking to produce gasoline. In this method, both the fluidized bed and fixed bed reactors operate at relatively high reaction pressures, and the effluent from the fluidized bed reactor directly enters the fixed bed reactor. The H2S in the mixture effluent from the fluidized bed reactor can negatively impact the desulfurization efficiency of the fixed bed reactor. Summary of the Invention

[0005] The applicant of this invention has discovered that the existing production methods for low-sulfur marine fuel oil require high pressure, resulting in high equipment costs, or the H2S gas generated earlier hinders the deep desulfurization reaction in the fixed-bed reactor, leading to lower product quality.

[0006] In view of the above problems, it is necessary to propose a method for producing low-sulfur marine fuel oil to solve or partially solve these problems. The technical solution proposed by this invention is as follows:

[0007] In a first aspect, the present invention provides a method for producing low-sulfur marine fuel oil, comprising:

[0008] The raw material hydrogen and the raw material heavy oil containing the first catalyst are preheated and then enter the first bubble breaking unit. The raw material hydrogen is broken into microbubbles by the first bubble breaking unit and dispersed in the raw material heavy oil. The raw material heavy oil and raw material hydrogen mixture coming out of the first bubble breaking unit are preheated and then enter the slurry bed reactor to undergo the first hydrogenation reaction to obtain the first reaction product.

[0009] The first reaction product from the slurry bed reactor is separated by the first separation unit to obtain a preliminary light fraction and a first heavy fraction;

[0010] The initial light fraction is separated by the second separation unit to obtain a first gaseous product and a light fraction product;

[0011] The first heavy fraction and the light fraction product are respectively mixed with the feed hydrogen and then fed into the fixed bed reactor to carry out a second hydrogenation reaction to obtain the second reaction product;

[0012] The second reaction product from the fixed-bed reactor is separated into a second gaseous product and a liquid product by a third separation unit.

[0013] The liquid phase product is divided into a first stream and a second stream according to a preset ratio. The first stream enters a distillation tower for distillation to obtain dry gas, naphtha, diesel oil, and a second heavy fraction. The second stream flows out from the third separation unit.

[0014] Furthermore, the separation of the first reaction product from the slurry bed reactor into a preliminary light fraction and a first heavy fraction by the first separation unit includes: the first reaction product from the slurry bed reactor enters a desolidification unit for desolidification, and the desolidified first reaction product is separated into a preliminary light fraction and a first heavy fraction by the first separation unit.

[0015] Furthermore, the first heavy fraction and the light fraction product are respectively mixed with feed hydrogen and then enter the fixed-bed reactor, including: after the first heavy fraction is mixed with feed hydrogen, the feed hydrogen is broken into microbubbles by a second bubble breaking unit and dispersed in the first heavy fraction, and the mixture of the first heavy fraction and feed hydrogen exiting the second bubble breaking unit enters the fixed-bed reactor; after the light fraction product is mixed with feed hydrogen, the feed hydrogen is broken into microbubbles by a third bubble breaking unit and dispersed in the light fraction product, and the mixture of the light fraction product and feed hydrogen exiting the third bubble breaking unit enters the fixed-bed reactor.

[0016] Furthermore, the light distillate product and the raw hydrogen mixture from the third bubble crushing unit enter the fixed bed reactor, including: the light distillate product and the raw hydrogen mixture from the third bubble crushing unit are a single stream or divided into multiple streams;

[0017] When the light distillate product and feed hydrogen mixture are a single stream, the light distillate product and feed hydrogen mixture enters from the middle of the fixed bed reactor;

[0018] When the light distillate product and the feed hydrogen mixture are divided into multiple streams, the light distillate product and the feed hydrogen mixture enter from the upper, middle and lower parts of the fixed bed reactor, respectively.

[0019] Furthermore, when the light distillate product and the raw hydrogen mixture are divided into multiple streams, each stream accounts for 10-50% of the total stream.

[0020] Furthermore, it also includes: the first gaseous product is desulfurized to obtain a first recycled feedstock hydrogen, and the first recycled feedstock hydrogen is mixed with new feedstock hydrogen and enters the slurry bed reactor as feedstock hydrogen; the second gaseous product is desulfurized to obtain a second recycled feedstock hydrogen, and the second recycled feedstock hydrogen is mixed with new feedstock hydrogen and enters the fixed bed reactor as feedstock hydrogen.

[0021] Furthermore, the size of the microbubbles is less than 1 mm.

[0022] Furthermore, the initial light distillate is a fraction with a boiling point <360°C.

[0023] Furthermore, the second stream and the second heavy fraction are used as different grades of marine fuel oil, or as raw materials for blending marine fuel oil.

[0024] Furthermore, the ratio of the first material to the second material is 1:9 to 9:1.

[0025] Furthermore, the material flow direction within the fixed-bed reactor is either from top to bottom or from bottom to top.

[0026] Furthermore, the fixed-bed reactor is filled with at least two catalyst beds, with at least one catalyst bed in the lower part and at least one catalyst bed in the upper part.

[0027] Furthermore, the fixed-bed reactor is packed with a second catalyst, which is one or more of a hydrogenation protective agent, a hydrogenation demetallization catalyst, a hydrogenation desulfurization catalyst, and a hydrogenation decarbonization catalyst. The second catalyst contains an active metal and a support. The active metal contains at least one of a Group VI metal and / or a Group VIII metal, and the support contains at least one of alumina, amorphous aluminum silicate, and silica.

[0028] Furthermore, the reaction conditions of the fixed-bed reactor are as follows: reaction temperature 360–400℃, reaction pressure 8–14 MPa, and liquid hourly space velocity 0.3–1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 600–1600.

[0029] Furthermore, the reaction conditions of the slurry bed reactor are as follows: reaction temperature of 400–460℃, reaction pressure of 10–16 MPa, and liquid hourly space velocity of 0.1–1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 800–1600, the concentration of the first catalyst is 800–2000 ppm, and the concentration of the first catalyst is measured by the content of active metal in the first catalyst.

[0030] Furthermore, the hydrodesulfurization rate of the slurry bed reactor is 50-80%, the residual carbon removal rate is 60-80%, and the content of nickel and vanadium in the hydrogenation products is <180ppm.

[0031] Furthermore, the feedstock heavy oil can be one or more of atmospheric residue, vacuum residue, heavy oil, oil sands bitumen, and coal tar.

[0032] Furthermore, the first catalyst is a solid powder catalyst with molybdenum as the active metal.

[0033] Secondly, this invention proposes a production apparatus for low-sulfur marine fuel oil, comprising a first bubble breaking unit, a slurry bed reactor, a first separation unit, a second separation unit, a fixed bed reactor, a third separation unit, and a distillation column, wherein:

[0034] The first bubble breaking unit is used to break the incoming raw material hydrogen into microbubbles, disperse them in the incoming raw material heavy oil, and then transport them to the slurry bed reactor.

[0035] The slurry bed reactor is used to perform a first hydrogenation reaction on the feedstock heavy oil and feedstock hydrogen from the first bubble crushing unit to obtain a first reaction product and deliver it to the first separation unit.

[0036] The first separation unit is used to separate the first reaction product to obtain a preliminary light fraction and a first heavy fraction, and to transport the preliminary light fraction to the second separation unit, and to mix the first heavy fraction with the feed hydrogen and then transport it to the fixed bed reactor;

[0037] The second separation unit is used to separate the preliminary light fraction to obtain a first gaseous product and a light fraction product, and to mix the light fraction product with the feed hydrogen and then transport it to the fixed bed reactor.

[0038] The fixed-bed reactor is used to perform a second hydrogenation reaction on the first heavy fraction and the light fraction product to obtain a second reaction product, which is then transported to a third separation unit.

[0039] The third separation unit is used to separate the second reaction product to obtain a second gaseous product and a liquid product, divide the liquid product into a first stream and a second stream according to a preset ratio, and send the first stream into a distillation column and discharge the second stream.

[0040] The distillation tower is used to distill the first stream of material to obtain dry gas, naphtha, diesel oil, and a second heavy fraction, and to discharge the second heavy fraction from the bottom.

[0041] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0042] The method for producing low-sulfur marine fuel oil proposed in this invention involves a first bubble-breaking unit that breaks down the raw material hydrogen into microbubbles, effectively increasing the interphase area between hydrogen and the raw material heavy oil, enhancing the hydrogen dissolution process, thereby strengthening the hydrogenation reaction, reducing reaction pressure, decreasing equipment investment, and improving hydrogen utilization. The second separation unit effectively removes H2S gas from the first gaseous product generated in the slurry-bed reactor, preventing H2S gas from hindering the second hydrogenation reaction in the fixed-bed reactor and improving product quality. Furthermore, the first reaction product exiting the slurry-bed reactor is separated into a light fraction and a first heavy fraction, which are then fed into the fixed-bed reactor for hydrorefining, avoiding rapid catalyst deactivation at the fixed-bed front end and extending the equipment operating cycle. Attached Figure Description

[0043] Figure 1 This is a schematic flowchart of a method for producing low-sulfur marine fuel oil in an embodiment of the present invention.

[0044] Figure 2This is a schematic diagram of the production device for low-sulfur marine fuel oil in an embodiment of the present invention.

[0045] Figure 2 In this diagram, 1: slurry bed reactor; 2: fixed bed reactor; 3: distillation column; 4-1: first separation unit; 4-2: second separation unit; 4-3: third separation unit; 5-1: first bubble breaking unit; 5-2: second bubble breaking unit; 5-3: third bubble breaking unit; 6: desolidification unit; 7: feedstock heavy oil; 8-1: feedstock hydrogen; 8-2: feedstock hydrogen; 8-3: feedstock hydrogen; 9-1: first gaseous product; 9-2: second gaseous product; 10: second stream of material; 11: dry gas; 12: naphtha; 13: diesel oil; 14: second heavy fraction. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] This invention provides a method for producing low-sulfur marine fuel oil, such as... Figure 1 As shown, it includes:

[0048] Step S101: The raw material hydrogen and the raw material heavy oil containing the first catalyst are preheated and then enter the first bubble breaking unit. The raw material hydrogen is broken into microbubbles by the first bubble breaking unit and dispersed in the raw material heavy oil. The mixture of raw material heavy oil and raw material hydrogen exiting the first bubble breaking unit is preheated and then enters the slurry bed reactor to undergo the first hydrogenation reaction to obtain the first reaction product. The microbubble size is less than 1 mm.

[0049] Step S102: The first reaction product from the slurry bed reactor is separated by a first separation unit to obtain a preliminary light fraction and a first heavy fraction. The preliminary light fraction is a fraction with a boiling point <360℃.

[0050] Step S103: The preliminary light fraction is separated by the second separation unit to obtain the first gas phase product and the light fraction product.

[0051] Step S104: The first heavy fraction and the light fraction product are mixed with the raw material hydrogen and then fed into the fixed bed reactor to carry out the second hydrogenation reaction to obtain the second reaction product.

[0052] Step S105: The second reaction product from the fixed bed reactor is separated into a second gaseous product and a liquid product by the third separation unit.

[0053] Step S106: The liquid phase product is divided into a first stream and a second stream according to a preset ratio. The first stream enters a distillation tower for distillation to obtain dry gas, naphtha, diesel oil, and a second heavy fraction. The second stream flows out from the third separation unit.

[0054] In this embodiment, the first reaction product obtained from the slurry bed reactor is divided into a preliminary light fraction and a first heavy fraction. The first heavy fraction preferentially enters the fixed bed reactor from the top of the reactor (when the material flows from top to bottom) or the bottom of the reactor (when the material flows from bottom to top). Thus, the catalyst at the front end of the fixed bed reactor mainly treats impurities in the first heavy fraction. The light fraction product separated from the preliminary light fraction enters the fixed bed reactor from the upper to lower middle section of the reactor. This segmentally removes impurities from the first reaction product of the slurry bed reactor. On the one hand, it avoids the accelerated coking of the catalyst in the first half due to the large heat release at the front end of the fixed bed reactor, thus extending the overall service life of the catalyst in the reactor and extending the equipment operation cycle. On the other hand, it can better remove impurities from the heavy fraction.

[0055] The method for producing low-sulfur marine fuel oil proposed in this invention involves a first bubble-breaking unit that breaks down the raw material hydrogen into microbubbles, effectively increasing the interphase area between hydrogen and the raw material heavy oil, enhancing the hydrogen dissolution process, thereby strengthening the hydrogenation reaction, reducing reaction pressure, decreasing equipment investment, and improving hydrogen utilization. The second separation unit effectively removes H2S gas from the first gaseous product generated in the slurry-bed reactor, preventing H2S gas from hindering the second hydrogenation reaction in the fixed-bed reactor and improving product quality. Furthermore, the first reaction product exiting the slurry-bed reactor is separated into a light fraction and a first heavy fraction, which are then fed into the fixed-bed reactor for hydrorefining, avoiding rapid catalyst deactivation at the fixed-bed front end and extending the equipment operating cycle.

[0056] In one embodiment, step S102, in which the first reaction product from the slurry bed reactor is separated into a preliminary light fraction and a first heavy fraction by a first separation unit, includes: the first reaction product from the slurry bed reactor enters a desolidification unit for desolidification, and the desolidified first reaction product is separated into a preliminary light fraction and a first heavy fraction by the first separation unit.

[0057] In one embodiment, in step S104, the first heavy fraction and the light fraction product are respectively mixed with feed hydrogen and then enter the fixed-bed reactor. This includes: after the first heavy fraction is mixed with the feed hydrogen, the feed hydrogen is broken into microbubbles by a second bubble-breaking unit and dispersed in the first heavy fraction; the mixture of the first heavy fraction and feed hydrogen exiting the second bubble-breaking unit then enters the fixed-bed reactor. After the light fraction product is mixed with the feed hydrogen, the feed hydrogen is broken into microbubbles by a third bubble-breaking unit and dispersed in the light fraction product; the mixture of the light fraction product and feed hydrogen exiting the third bubble-breaking unit then enters the fixed-bed reactor. The size of the microbubbles is less than 1 mm.

[0058] In one embodiment, the light distillate product and feed hydrogen mixture exiting the third bubble crushing unit enters the fixed-bed reactor, comprising: the light distillate product and feed hydrogen mixture exiting the third bubble crushing unit being a single stream or divided into multiple streams; when the light distillate product and feed hydrogen mixture are a single stream, the light distillate product and feed hydrogen mixture enter from the middle of the fixed-bed reactor; when the light distillate product and feed hydrogen mixture are divided into multiple streams, the light distillate product and feed hydrogen mixture enter from the upper, middle and lower parts of the fixed-bed reactor, respectively.

[0059] In a further embodiment, when the light distillate product and the raw hydrogen mixture are divided into multiple streams, each stream accounts for 10-50% of the total stream.

[0060] In one embodiment, the first gaseous product is desulfurized to obtain a first recycled feedstock hydrogen, which is mixed with new feedstock hydrogen and enters the slurry bed reactor as feedstock hydrogen; the second gaseous product is desulfurized to obtain a second recycled feedstock hydrogen, which is mixed with new feedstock hydrogen and enters the fixed bed reactor as feedstock hydrogen.

[0061] In one embodiment, the second stream and the second heavy fraction are used as different grades of marine fuel oil, or as a blending feedstock for marine fuel oil.

[0062] In one embodiment, the ratio of the first material to the second material is 1:9 to 9:1.

[0063] In one embodiment, the material flow direction within the fixed-bed reactor is either from top to bottom or from bottom to top.

[0064] In one embodiment, the fixed-bed reactor is filled with at least two catalyst beds, with at least one catalyst bed at the bottom and at least one catalyst bed at the top.

[0065] In one embodiment, the fixed-bed reactor is packed with a second catalyst, which is one or more of a hydroprotective agent, a hydrodemetallization catalyst, a hydrodesulfurization catalyst, and a hydrodecarbonization catalyst. The second catalyst contains an active metal and a support, wherein the active metal contains at least one of a Group VI metal and / or a Group VIII metal, and the support contains at least one of alumina, amorphous aluminum silicate, and silica.

[0066] In one embodiment, the reaction conditions of the fixed-bed reactor are: reaction temperature of 360–400°C, reaction pressure of 8–14 MPa, and liquid hourly space velocity of 1.0–2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 600–1600.

[0067] In one embodiment, the reaction conditions of the slurry bed reactor are: a reaction temperature of 400–460°C, a reaction pressure of 10–16 MPa, and a liquid hourly space velocity of 0.1–1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 800–1600, the concentration of the first catalyst is 800–2000 ppm, and the concentration of the first catalyst is measured by the content of active metal in the first catalyst.

[0068] In one embodiment, the hydrodesulfurization rate of the slurry bed reactor is 50-80%, the residual carbon removal rate is 60-80%, and the content of nickel and vanadium in the hydrogenation product is <180ppm.

[0069] In one embodiment, the feedstock heavy oil may be one or more of atmospheric residue, vacuum residue, heavy oil, oil sands bitumen, and coal tar.

[0070] In one embodiment, the first catalyst is a solid powder catalyst with molybdenum as the active metal.

[0071] In the embodiments and comparative examples of this invention, the feedstock heavy oil is vacuum residue, the properties of which are shown in Table 1. This invention presents four embodiments and two comparative examples:

[0072]

[0073]

[0074] Table 1

[0075] Example 1

[0076] This embodiment uses vacuum residue as feedstock. First, the vacuum residue and feedstock hydrogen enter the first bubble crushing unit, where the hydrogen is broken into microbubbles with a size of 1 mm or less. Then, the mixture enters a slurry bed reactor for the first hydrogenation reaction, yielding the first reaction product. The operating conditions of the slurry bed reactor are: reaction temperature 400℃, reaction pressure 10 MPa, hydrogen-to-oil ratio 800, and liquid hourly space velocity (LISH) 0.1 h⁻¹. -1 The first catalyst concentration is 2000 ppm. The first reaction product from the slurry-bed reactor is desolidified in the desolidification unit and then enters the first separation unit to obtain a preliminary light fraction and a first heavy fraction. The first heavy fraction and feed hydrogen enter the second bubble-breaking unit, and then enter the fixed-bed reactor for further hydrogenation and refining. The aforementioned preliminary light fraction enters the second separation unit to obtain a light fraction product and a first gaseous product. The light fraction product and feed hydrogen enter the third bubble-breaking unit, and then enter the fixed-bed reactor from the middle of the fixed bed for further hydrogenation and refining. A second hydrogenation reaction occurs in the fixed-bed reactor to obtain the second reaction product. The operating conditions of the fixed-bed reactor are: reaction temperature 400℃, reaction pressure 14 MPa, hydrogen-to-oil ratio 1600, and liquid hourly space velocity 1 h⁻¹. -1 The second reaction product obtained from the fixed-bed reactor is separated in the third separation unit to obtain a liquid product and a second gaseous product. Finally, part of the liquid product is separated by a distillation column to obtain dry gas, naphtha, diesel oil, and a second heavy fraction. The first and second gaseous products are then used for hydrogen recycling after H2S removal and other impurity removal operations. The reaction results are shown in Table 2.

[0077]

[0078]

[0079] Table 2

[0080] Example 2

[0081] The difference between this embodiment and Embodiment 1 is that the operating conditions of the slurry bed reactor are as follows: reaction temperature 460℃, reaction pressure 16 MPa, hydrogen-to-oil ratio 1600, and liquid hourly space velocity 1.0 h⁻¹. -1 The first catalyst concentration was 800 ppm. The fixed-bed reactor operating conditions were: reaction temperature 360℃, reaction pressure 8 MPa, hydrogen-to-oil ratio 600, and liquid hourly space velocity 0.3 h⁻¹. -1 The reaction results are shown in Table 2.

[0082] Example 3

[0083] The difference between this embodiment and Embodiment 1 is that the operating conditions of the slurry bed reactor are: reaction temperature of 430℃, reaction pressure of 14 MPa, hydrogen-to-oil ratio of 1200, and liquid hourly space velocity of 0.3 h⁻¹. -1The first catalyst concentration was 1400 ppm; the fixed-bed reactor operating conditions were: reaction temperature 380℃, reaction pressure 12 MPa, hydrogen-to-oil ratio 1200, and liquid hourly space velocity 0.6 h⁻¹. -1 The reaction results are shown in Table 2.

[0084] Example 4

[0085] The difference between this embodiment and Embodiment 3 is that the preliminary light fraction obtained after separation by the first separation unit is mixed with hydrogen by the third bubble crushing unit and then divided into three streams that enter the upper, middle, and lower parts of the fixed-bed reactor, respectively. The reaction results are shown in Table 2.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 3 is that the first bubble breaking unit, the second bubble breaking unit, and the third bubble breaking unit are not used. The reaction results are shown in Table 2.

[0088] As can be seen from Table 2, the S content in the first reaction product obtained by the slurry bed reactor in Comparative Example 1 is higher than that in Example 3, and the S content in the second reaction product obtained by the fixed bed reactor in Comparative Example 1 is higher than that in Example 3. Therefore, the hydrogenation reaction in Example 3 is more complete. The use of the first bubble breaking unit, the second bubble breaking unit and the third bubble breaking unit to break the raw material hydrogen into microbubbles can effectively increase the phase interface area between hydrogen and raw material heavy oil, enhance the hydrogen dissolution process, and thus enhance the first and second hydrogenation reaction processes.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 3 is that the first bubble breaking unit, the second bubble breaking unit, and the third bubble breaking unit are not used; and the first separation unit is not used to separate the first reaction product obtained from the slurry bed reactor into a preliminary light fraction and a first heavy fraction. After gas-liquid separation, the liquid phase product and the raw material hydrogen are mixed in the pipeline and then directly enter the fixed bed reactor. The reaction results are shown in Table 2.

[0091] As shown in Table 2, the sulfur (S) content in the first reaction product obtained from the slurry-bed reactor in Comparative Example 2 and the second reaction product obtained from the fixed-bed reactor are higher than those in Example 3; and the content of impurities such as sulfur in the second reaction product obtained from the fixed-bed reactor is higher than that in Comparative Example 1. Therefore, the use of the bubble breaking unit can effectively enhance the first and second hydrogenation reaction processes; and the use of the first separation unit to separate the first reaction product obtained from the slurry-bed reactor into a preliminary light fraction and a first heavy fraction can remove impurities such as sulfur from the first reaction product of the slurry-bed reactor in stages, thereby improving product quality.

[0092] Based on the same inventive concept, embodiments of the present invention also propose a production apparatus for low-sulfur marine fuel oil, such as... Figure 2 As shown, it includes a first bubble breaking unit 5-1, a slurry bed reactor 1, a first separation unit 4-1, a second separation unit 4-2, a fixed bed reactor 2, a third separation unit 4-3, and a distillation column 3, wherein:

[0093] The first bubble breaking unit 5-1 is used to break the incoming raw material hydrogen gas 8-1 into microbubbles, disperse them in the incoming raw material heavy oil 7, and then transport them to the slurry bed reactor 1.

[0094] The slurry bed reactor 1 is used to perform a first hydrogenation reaction on the feedstock heavy oil 7 and the feedstock hydrogen 8-1 from the first bubble breaking unit 5-1 to obtain a first reaction product and transport it to the first separation unit 4-1.

[0095] The first separation unit 4-1 is used to separate the first reaction product to obtain a preliminary light fraction and a first heavy fraction, and to transport the preliminary light fraction to the second separation unit 4-2, and to mix the first heavy fraction with the raw material hydrogen gas 8-2 and then transport it to the fixed bed reactor 2.

[0096] The second separation unit 4-2 is used to separate the preliminary light fraction to obtain the first gaseous product 9-1 and the light fraction product, and then mix the light fraction product with the raw material hydrogen 8-3 and transport it to the fixed bed reactor 2.

[0097] The fixed-bed reactor 2 is used to perform a second hydrogenation reaction on the first heavy fraction and the light fraction products to obtain a second reaction product, which is then transported to the third separation unit 4-3.

[0098] The third separation unit 4-3 is used to separate the second reaction product to obtain a second gaseous product 9-2 and a liquid product. The liquid product is divided into a first material and a second material 10 according to a preset ratio. The first material is sent into the distillation tower 3 and the second material 10 is discharged.

[0099] The distillation tower 3 is used to distill the first stream of material to obtain dry gas 11, naphtha 12, diesel oil 13, and a second heavy fraction 14, and to discharge the second heavy fraction 14 from the bottom.

[0100] In one embodiment, the low-sulfur marine fuel oil production apparatus further includes a desolidification unit 6, which is connected to the slurry bed reactor 1 and the first separation unit 4-1, respectively, for desolidifying the first reaction product from the slurry bed reactor 1 and conveying the desolidified first reaction product to the first separation unit 4-1.

[0101] In one embodiment, the low-sulfur marine fuel oil production apparatus further includes a second bubble breaking unit 5-2 and a third bubble breaking unit 5-3;

[0102] The second bubble breaking unit 5-2 is connected to the first separation unit 4-1 and the fixed bed reactor 2 respectively, and is used to break the raw material hydrogen 8-2 into microbubbles and disperse them in the first heavy fraction delivered by the first separation unit 4-1, and to deliver the mixture of the first heavy fraction and the raw material hydrogen 8-2 to the fixed bed reactor 2.

[0103] The third bubble breaking unit 5-3 is connected to the second separation unit 4-2 and the fixed bed reactor 2, respectively. It is used to break the raw material hydrogen gas 8-3 into microbubbles and disperse them in the light distillate product delivered by the second separation unit 4-2, and to introduce the mixture of the light distillate product and the raw material hydrogen gas 8-3 into the fixed bed reactor 2.

[0104] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0105] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A method for producing low-sulfur marine fuel oil, characterized in that, include: The raw material hydrogen and the raw material heavy oil containing the first catalyst are preheated and then enter the first bubble breaking unit. The raw material hydrogen is broken into microbubbles by the first bubble breaking unit and dispersed in the raw material heavy oil. The raw material heavy oil and raw material hydrogen mixture coming out of the first bubble breaking unit are preheated and then enter the slurry bed reactor to undergo the first hydrogenation reaction to obtain the first reaction product. The first reaction product from the slurry bed reactor enters the desolidification unit for desolidification, and the desolidified first reaction product is separated by the first separation unit to obtain a preliminary light fraction and a first heavy fraction. The initial light fraction is separated by a second separation unit to obtain a first gaseous product and a light fraction product; the second separation unit removes H2S gas from the first gaseous product generated in the slurry bed reactor; the first gaseous product is desulfurized to obtain a first recycled feedstock hydrogen, and the first recycled feedstock hydrogen is mixed with new feedstock hydrogen and enters the slurry bed reactor as feedstock hydrogen. The first heavy fraction and the light fraction product are respectively mixed with the feed hydrogen and then fed into a fixed bed reactor to carry out a second hydrogenation reaction to obtain the second reaction product; The second reaction product from the fixed bed reactor is separated into a second gaseous product and a liquid product by a third separation unit; the second gaseous product is desulfurized to obtain a second recycled feedstock hydrogen, which is mixed with new feedstock hydrogen and enters the fixed bed reactor as feedstock hydrogen. The liquid product is divided into a first stream and a second stream according to a preset ratio. The first stream enters a distillation tower for distillation to obtain dry gas, naphtha, diesel, and a second heavy fraction. The second stream flows out from the third separation unit. The first heavy fraction enters the fixed-bed reactor from the top or bottom of the reactor, while the light fraction product enters the fixed-bed reactor from the upper to lower middle section of the reactor. The second stream and the second heavy fraction are used as different grades of marine fuel oil, or as raw materials for blending marine fuel oil.

2. The method as described in claim 1, characterized in that, The first heavy fraction and the light fraction product are respectively mixed with feed hydrogen and then enter the fixed-bed reactor. The process includes: after the first heavy fraction is mixed with feed hydrogen, the feed hydrogen is broken into microbubbles by a second bubble breaking unit and dispersed in the first heavy fraction. The mixture of the first heavy fraction and feed hydrogen exiting the second bubble breaking unit enters the fixed-bed reactor. After the light fraction product is mixed with feed hydrogen, the feed hydrogen is broken into microbubbles by a third bubble breaking unit and dispersed in the light fraction product. The mixture of the light fraction product and feed hydrogen exiting the third bubble breaking unit enters the fixed-bed reactor.

3. The method as described in claim 2, characterized in that, The light distillate product and the raw hydrogen mixture from the third bubble crushing unit enter the fixed bed reactor, including: the light distillate product and the raw hydrogen mixture from the third bubble crushing unit are a single stream or divided into multiple streams; When the light distillate product and feed hydrogen mixture are a single stream, the light distillate product and feed hydrogen mixture enters from the middle of the fixed bed reactor; When the light distillate product and the feed hydrogen mixture are divided into multiple streams, the light distillate product and the feed hydrogen mixture enter from the upper, middle and lower parts of the fixed bed reactor, respectively.

4. The method as described in claim 3, characterized in that, The size of the microbubbles is less than 1 mm.

5. The method as described in claim 4, characterized in that, The initial light distillate is a fraction with a boiling point <360℃.

6. The method as described in claim 5, characterized in that, The material flow direction in the fixed-bed reactor is either from top to bottom or from bottom to top.

7. The method as described in claim 6, characterized in that, The fixed-bed reactor is filled with at least two catalyst beds, with at least one catalyst bed at the bottom and at least one catalyst bed at the top.

8. The method as described in claim 7, characterized in that, The fixed-bed reactor is packed with a second catalyst, which is one or more of the following: a hydrogenation protective agent, a hydrogenation demetallization catalyst, a hydrogenation desulfurization catalyst, and a hydrogenation decarbonization catalyst. The second catalyst contains an active metal and a support. The active metal of the second catalyst contains at least one of a Group VI metal and / or a Group VIII metal, and the support of the second catalyst contains at least one of alumina, amorphous silica-alumina, and silica.

9. The method according to any one of claims 1-8, characterized in that, The reaction conditions of the fixed-bed reactor are as follows: reaction temperature 360~400℃, reaction pressure 8~14 MPa, and liquid hourly space velocity 0.3~1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 600-1600.

10. The method according to any one of claims 1-8, characterized in that, The reaction conditions of the slurry bed reactor are as follows: reaction temperature 400~460℃, reaction pressure 10~16 MPa, and liquid hourly space velocity 0.1~1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 800-1600, the concentration of the first catalyst is 800-2000 ppm, and the concentration of the first catalyst is measured by the content of active metal in the first catalyst.

11. The method according to any one of claims 1-8, characterized in that, The slurry bed reactor has a hydrodesulfurization rate of 50-80%, a residual carbon removal rate of 60-80%, and the content of nickel and vanadium in the hydrogenation products is <180 ppm.

12. The method according to any one of claims 1-8, characterized in that, The raw material heavy oil is viscous heavy oil.

13. The method according to any one of claims 1-8, characterized in that, The raw material heavy oil is one or more of atmospheric residue, vacuum residue, oil sands asphalt, and coal tar.

14. The method according to any one of claims 1-8, characterized in that, The first catalyst is a solid powder catalyst with molybdenum as the active metal.

15. A production apparatus for low-sulfur marine fuel oil, characterized in that, It includes a first bubble breaking unit, a slurry bed reactor, a desolidification unit, a first separation unit, a second separation unit, a fixed bed reactor, a third separation unit, and a distillation column, wherein: The first bubble breaking unit is used to break the incoming raw material hydrogen into microbubbles, disperse them in the incoming raw material heavy oil, and transport them to the slurry bed reactor. The slurry bed reactor is used to perform a first hydrogenation reaction on the feedstock heavy oil and feedstock hydrogen from the first bubble crushing unit to obtain a first reaction product and deliver it to the first separation unit. The desolidification unit is connected to the slurry bed reactor and the first separation unit respectively, and is used to desolidify the first reaction product from the slurry bed reactor and transport the desolidified first reaction product to the first separation unit. The first separation unit is used to separate the first reaction product to obtain a preliminary light fraction and a first heavy fraction, and to transport the preliminary light fraction to the second separation unit, and to mix the first heavy fraction with the feed hydrogen and then transport it to the fixed bed reactor; The second separation unit is used to separate the preliminary light fraction to obtain a first gaseous product and a light fraction product, and to mix the light fraction product with the feed hydrogen and then transport it to the fixed bed reactor; the second separation unit removes H2S gas from the first gaseous product generated in the slurry bed reactor; The fixed-bed reactor is used to perform a second hydrogenation reaction on the first heavy fraction and the light fraction product to obtain a second reaction product, which is then transported to a third separation unit. The third separation unit is used to separate the second reaction product to obtain a second gaseous product and a liquid product, divide the liquid product into a first stream and a second stream according to a preset ratio, and send the first stream into a distillation column and discharge the second stream. The distillation column is used to distill the first stream of material to obtain dry gas, naphtha, diesel oil and a second heavy fraction, and to discharge the second heavy fraction from the bottom. The first heavy fraction enters the fixed-bed reactor from the top or bottom of the reactor, while the light fraction product enters the fixed-bed reactor from the upper to lower middle section of the reactor. The second stream and the second heavy fraction are used as different grades of marine fuel oil, or as raw materials for blending marine fuel oil.

16. The apparatus as claimed in claim 15, characterized in that, It also includes a second bubble breaking unit and a third bubble breaking unit; The second bubble breaking unit is connected to the first separation unit and the fixed bed reactor respectively, and is used to break the raw material hydrogen into microbubbles and disperse them in the first heavy fraction delivered by the first separation unit, and to deliver the mixture of the first heavy fraction and the raw material hydrogen to the fixed bed reactor. The third bubble breaking unit is connected to the second separation unit and the fixed bed reactor, respectively, and is used to break the raw hydrogen into microbubbles and disperse them in the light distillate product delivered by the second separation unit, and to introduce the mixture of the light distillate product and the raw hydrogen into the fixed bed reactor.

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