A method for processing a residual hydrodesiel fuel

Abstract

The present application relates to a method for processing residual oil hydrodesiel fuel, which is processed by using hydrocracking technology, i.e. the residual oil hydrodesiel fuel is used as raw material of a hydrocracking device, and the hydrocracking device is a light oil type hydrocracking device. The method disclosed in the present application widens the raw material source of the device, optimizes the processing route of the residual oil hydrodesiel fuel, provides a successful case for the optimized utilization of the residual oil hydrodesiel fuel, converts most of the components of the residual oil hydrodesiel fuel into gasoline components, effectively reduces the diesel component, and optimizes the product structure. The residual oil hydrodesiel fuel as the raw material of the hydrocracking device is beneficial to the increase of the cetane number of the diesel product, the reduction of the sulfur content of the diesel product, the improvement of the feed property of a reforming device, and the improvement of the product quality.

Description

Technical Field

[0001] This invention relates to a method for processing hydrogenated diesel fuel from residual oil. Background Technology

[0002] Hydrocracking units have played a certain role in reducing diesel fuel consumption. By appropriately processing diesel components such as catalytic diesel and straight-run diesel, the industrial practice of maximizing the production of non-diesel products such as light naphtha, heavy naphtha, or jet fuel is currently quite common.

[0003] Hydrogenated diesel is one of the main products of hydrogenated residue oil. How to achieve high added value utilization of hydrogenated diesel is an urgent problem for researchers and refining companies. There are no reports of cases of processing hydrogenated diesel through hydrocracking.

[0004] This invention mainly studies the processing of hydrotreated diesel fuel from residue in a hydrocracking unit, providing a reference for the processing route of hydrotreated diesel fuel from residue.

[0005] ①CN110655954A discloses an ultra-deep desulfurization method for hydrogenated diesel fuel from residual oil. The method includes the following steps: a. Fractionating the hydrogenated diesel fuel from residual oil to obtain light fraction and heavy fraction, wherein the cut-off temperature of the light fraction and the heavy fraction is 331~355℃.

[0006] b. The light fraction obtained in step a is subjected to hydrodesulfurization treatment to obtain the first part of ultra-low sulfur diesel fraction;

[0007] c. The heavy fraction obtained in step a is subjected to oxidative desulfurization treatment to obtain the second part of ultra-low sulfur diesel fraction.

[0008] This method can effectively remove sulfur compounds from hydrogenated diesel fuel. Compared with existing technologies, it reduces the harshness of diesel hydrogenation units, extends the operating time of diesel hydrogenation units, and reduces the amount of oxidant and extractant used. It also has a high oil yield and good economic benefits.

[0009] The first and second ultra-low sulfur diesel fractions were mixed to obtain an ultra-low sulfur diesel product with a sulfur content of 7.1 μg / g.

[0010] ② Xu Dahai, Niu Shikun, et al. conducted a feasibility study on the production of diesel fuel that meets the GB19147-2016 vehicle diesel standard (National V vehicle diesel standard) by blending diesel fractions produced by the fluidized bed residue hydrotreating unit into a diesel hydrotreating unit (referred to as fluidized bed hydrotreated diesel).

[0011] The results show that blending a certain proportion of fluidized bed hydrotreated diesel fraction into a conventional diesel hydrotreating unit can produce a blending component for China V standard vehicle diesel.

[0012] Straight-run diesel was blended with 30% fluidized bed hydrotreated diesel at a reaction pressure of 6.5 MPa and a volume hourly space velocity of 1.5 h⁻¹. －１ Under the conditions of reaction temperature of 360 ℃ and hydrogen-to-oil volume ratio of 500, the refined diesel oil meets the China V standard for vehicle diesel oil.

[0013] 30% of fluidized bed hydrotreated diesel was blended with a mixture of straight-run diesel, coking diesel, and catalytic cracking diesel in a mass ratio of 62:25:13, and the reaction was carried out at a reaction pressure of 7.3 MPa and a volume hourly space velocity of 1.0 h⁻¹. -1 Under the conditions of reaction temperature of 355℃ and hydrogen-to-oil volume ratio of 500, it is possible to produce automotive diesel blending components with sulfur content that meet the National V standard.

[0014] ③ Fan Siqiang, Chen Pingping, and others processed hydrogenated diesel fuel from residue oil using three routes: hydrorefining, hydromodification, and LCO blending and hydromodification. Under the experimental conditions described in the paper, the hydrorefining route only increased the cetane index of the refined oil by 2.25 units and could not reduce diesel production, so the technological advantage was not significant.

[0015] Hydrotreating can convert hydrogenated diesel fuel from residual oil into chemical feedstocks such as light naphtha and heavy naphtha, while significantly improving the quality of diesel products. At a treatment temperature of 375℃, a 42% heavy naphtha fraction can be obtained, with an aromatic potential of 54%, making it a high-quality feedstock for catalytic reforming. Simultaneously, 49% modified diesel fuel can be obtained, with a cetane index of 51.5 and a polycyclic aromatic hydrocarbon (PAH) mass fraction of less than 2.5%, and sulfur and nitrogen mass fractions both less than 10 μg / g, meeting the China VI diesel fuel standard. This technology has a certain degree of market competitiveness.

[0016] Combining the poor properties and high processing difficulty of LCO with the low yield and excellent properties of hydrogenated diesel from residual oil, mixing LCO with hydrogenated diesel from residual oil for hydrotreating results in low operating load, high processing capacity, and excellent product quality. This is an effective technical route for enterprises to reduce diesel production and achieve high-value-added utilization of diesel.

[0017] ④ Zhang Wei conducted a hydrogenation process test and investigation on the production of diesel fuel that meets the National VI standard by hydrogenating the diesel fraction of the fluidized bed residue oil.

[0018] The results showed that using hydrotreated diesel fraction from fluidized bed residue oil as feedstock, at a reaction pressure of 6.5–7.5 MPa and a volume hourly space velocity of 1.0–1.5 h⁻¹, the reaction was successful. -1 Under process conditions of an average reaction temperature of 350–375℃ and a hydrogen-to-oil volume ratio of 400, the refined diesel fuel (except for the cetane number) meets the China VI standard for automotive diesel fuel.

[0019] As the distillation range of the diesel fraction from the hydrotreated residue oil in the fluidized bed increases, the difficulty of hydrodesulfurization increases significantly.

[0020] It is recommended that when producing diesel fuel that meets the China VI standard, the final boiling point should be controlled to be no higher than 340℃, which is beneficial for the hydrogenation unit to achieve long-term operation under relatively mild operating conditions.

[0021] When processing fluidized bed hydrotreated diesel fractions with a higher distillation range, it is recommended to blend them into existing diesel hydrorefining or hydrotreating units in a certain proportion to reduce processing difficulty.

[0022] Through research on patents, literature and other materials, it was found that the conventional processing methods for hydrogenated diesel fuel use diesel refining or diesel hydrotreating technology to produce qualified diesel products. However, these methods have problems such as low cetane number of diesel products and low ability to convert diesel into non-diesel components. Summary of the Invention

[0023] The purpose of this invention is to provide a method for processing hydrogenated diesel fuel from residual oil. This method uses hydrocracking technology to process hydrogenated diesel fuel from residual oil, which broadens the source of raw materials for the equipment, optimizes the processing route for hydrogenated diesel fuel from residual oil, effectively reduces the composition of diesel fuel, optimizes the product structure, and improves the quality of diesel fuel products.

[0024] The objective of this invention is achieved as follows: The present invention relates to a method for processing hydrogenated diesel fuel from residual oil, wherein the method employs hydrocracking technology, that is, using hydrogenated diesel fuel from residual oil as feedstock for processing in a hydrocracking unit.

[0025] The present invention discloses a method for processing hydrogenated diesel fuel from residual oil. The method involves the hydrogenated diesel fuel from residual oil entering the intermediate tank area for diesel components, and then the diesel fuel from the intermediate tank area entering the hydrocracking unit via the start-up diesel pipeline of the hydrocracking unit.

[0026] The present invention discloses a method for processing hydrotreated diesel fuel from residual oil. The method involves the hydrotreated diesel fuel from residual oil entering the hydrocracking unit via the start-up diesel line from the intermediate diesel component tank area. It is then fed into the feedstock buffer tank along with vacuum wax oil as feedstock for the hydrocracking unit. The feedstock oil is pressurized to 18.0 MPa by a reaction feed pump and mixed with circulating hydrogen. After being heated to 350–370°C by a reaction feed heater, it enters the hydrorefining reactor for desulfurization, denitrification, and dearomatics reactions. The refining reaction temperature is 350–390°C.

[0027] It then enters a hydrocracking reactor for cracking reaction at a temperature of 350–400°C.

[0028] After the reaction products are separated into gas and liquid by a high-low pressure separator and a stripping tower, the bottom oil of the stripping tower is heated to 350-370°C in a fractionation feed heater and then enters the fractionation tower for separation to produce naphtha, jet fuel and diesel products.

[0029] The present invention relates to a method for processing hydrogenated diesel fuel from residual oil. The hydrogenated diesel fuel is introduced into the unit from the intermediate diesel component tank area through the start-up diesel line of the hydrocracking unit. It enters the feedstock buffer tank together with vacuum wax oil. The blending ratio of hydrogenated diesel fuel is 21.4%. The feedstock oil is pressurized by the reaction feed pump and then mixed with circulating hydrogen. The hydrogen-to-oil ratio is greater than 1137.

[0030] The present invention relates to a method for processing hydrotreated diesel fuel from residual oil. The hydrocracking unit is a light oil type hydrocracking unit, which consists of reaction, fractionation, desulfurization and utilities sections. It adopts a single-stage full-cycle hydrocracking process. The unit uses vacuum wax oil as the main feedstock. The hydrorefining catalysts are HYT-6219-1.3T and KF-848-1.3Q, and the hydrocracking catalysts are HC-24L and HC-120. The operating pressure is 14.7 MPa.

[0031] The products are crude liquefied petroleum gas, light naphtha, heavy naphtha, aviation kerosene, and diesel oil, with a cetane number of ≥60.

[0032] The method for processing hydrogenated diesel fuel from residual oil according to the present invention uses a high-pressure hydrocracking unit with an operating pressure of 14.7 MPa.

[0033] The present invention relates to a method for processing hydrogenated diesel fuel from residual oil, wherein the hydrogenated diesel fuel is one of the products of a fixed-bed residual oil hydrogenation unit and belongs to diesel fuel components.

[0034] The present invention relates to a method for processing hydrogenated diesel fuel from residual oil. After being processed by a hydrocracking unit, the hydrogenated diesel fuel from residual oil is mostly converted into non-diesel components, including naphtha, jet fuel, and liquefied petroleum gas.

[0035] Introducing hydrotreated diesel fuel from residual oil into a hydrocracking unit with higher operating pressure improves hydrorefining efficiency and facilitates reactions such as aromatic saturation and heteroatom removal, resulting in high-quality diesel products. Furthermore, it leverages the hydrocracking reaction to crack the hydrotreated diesel fuel, simultaneously yielding high-value-added components such as jet fuel and gasoline. Therefore, hydrocracking technology is the preferred process route for processing hydrotreated diesel fuel from residual oil.

[0036] Compared with existing methods, the advantages of the method provided by this invention are mainly as follows: (1) The hydrocracking unit processes hydrogenated diesel from residue oil, which broadens the source of raw materials for the unit, optimizes the processing route of hydrogenated diesel from residue oil, and provides a successful case for the optimized utilization of hydrogenated diesel from residue oil.

[0037] (2) After processing the residue into hydrodiesel by the hydrocracking unit, the yield of light naphtha + heavy naphtha was 38.13%, which was 21.72% higher than the yield of hydrotreated naphtha of 16.41%.

[0038] The apparent conversion rate of hydrogenated residue diesel is 67.11% (conversion rate = 1 - diesel unconverted rate = 1 - diesel yield). Apparently, most of the hydrogenated residue diesel components are converted into non-diesel components, effectively reducing the diesel component and optimizing the product structure.

[0039] There is still some room for adjustment in the product yield of the unit. The yields of diesel, jet fuel, and naphtha can be further adjusted according to the company's production and operation situation.

[0040] (3) After the hydrocracking unit processes the residue oil into hydro-diesel, the cetane number of the diesel product is 62.7, but compared with the designed cetane number of 49.6 for hydro-modified diesel products, the cetane number of diesel is significantly increased.

[0041] Compared to the cetane number of 40.8 for hydrotreated diesel fuel (see Table 1), the cetane number increased by 21.9 units.

[0042] The aromatic potential of heavy naphtha increased by 2.2 units.

[0043] (4) Before and after the hydrocracking unit blended residue oil into hydrogenated diesel, the sulfur and nitrogen content of the diesel product were 1.3 mg / kg and <0.3 mg / kg, respectively, which is a significant improvement compared to the sulfur content of 1.8 mg / kg of the diesel product from the diesel hydrotreating unit.

[0044] (5) Hydrogenated diesel oil is processed using hydrocracking technology, which is beneficial to improving the cetane number of diesel oil in the whole plant, reducing the sulfur content of diesel products, improving the feed properties of the reforming unit, and improving the overall product quality of the plant. Attached Figure Description

[0045] Figure 1 This is a process flow diagram for processing hydrogenated diesel fuel from residual oil. Detailed Implementation

[0046] Figure 1 In the process, the components are: 1. Hydrogenated diesel oil; 2. Vacuum-reduced wax oil; 3. Feedstock buffer tank; 4. Reactor feed pump; 5. Reactor feed heater; 6. Hydrogenation refining reactor; 7. Hydrogenation cracking reactor; 8. Fractionation feed heater; 9. Fractionation tower; 10. Naphtha; 11. Aviation kerosene; 12. Diesel; and 13. Tail oil.

[0047] Hydrogenated diesel oil 1 and vacuum wax oil 2 are fed into feedstock buffer tank 3 as feedstock for hydrocracking unit (the blending ratio of hydrogenated diesel oil is 21.4%). The feedstock is pressurized to 18.0 MPa by reaction feed pump 4 and then mixed with circulating hydrogen (hydrogen-to-oil ratio greater than 1137). After being heated to 350-370°C by reaction feed heater 5, it enters hydrorefining reactor 6 for desulfurization, denitrification, and dearomatics reactions. The refining reaction temperature is 350-390°C.

[0048] It then enters the hydrocracking reactor 7 for cracking reaction at a temperature of 350–400°C.

[0049] After the reaction products are separated into gas and liquid by a high-low pressure separator and a stripping tower, the bottom oil of the stripping tower is heated to 350-370°C by a fractionation feed heater 8 and then enters the fractionation tower 9 for separation to produce naphtha 10, jet fuel 11, and diesel product 12.

[0050] The first trial of hydrocracking unit processing residue hydrodiesel was conducted. The blending rate of residue hydrodiesel was 30 t / h, the total feed rate of the unit was 140 t / h, and the blending ratio was 21.4%. The specific implementation steps are as follows: The amount of hydrotreated diesel fuel blended with residual oil was increased by 5t / h. As the amount of hydrotreated diesel fuel feed increased, the amount of vacuum wax oil feed was reduced simultaneously to keep the total feed of the unit constant at 140t / h.

[0051] After the unit is blended with 10 t / h of hydrotreated diesel fuel, the operating conditions are controlled as follows: reaction pressure 14.7 MPa, average refining reaction temperature 360 ​​℃, average cracking reaction temperature 359 ℃, hydrogen-to-oil volume ratio 1160, single-bed temperature rise of hydrorefining reactor 6 ≤ 42 ℃, single-bed temperature rise of hydrocracking reactor 7 ≤ 28 ℃, cold hydrogen valve opening ≤ 65%, liquid levels in high and low separation tanks, stripping tower, and fractionation tower 9 controlled at 55%, and outlet temperature of fractionation feed heater 8 controlled at 360 ℃.

[0052] Adjust the refining reaction temperature and cracking reaction temperature appropriately to stabilize the reaction depth, maintain the heavy naphtha yield at 36%, and operate stably for 24 hours.

[0053] The amount of hydrotreated diesel fuel blended with residual oil was increased by 5t / h. As the amount of hydrotreated diesel fuel feed increased, the amount of vacuum wax oil feed was reduced simultaneously to keep the total feed of the unit constant at 140t / h.

[0054] After the unit is blended with 20 t / h of hydrotreated diesel fuel, the operating conditions are controlled as follows: reaction pressure 14.7 MPa, average refining reaction temperature 360 ​​℃, cracking reaction temperature 357 ℃, hydrogen-to-oil volume ratio 1187, single-bed temperature rise of hydrorefining reactor 6 ≤ 42 ℃, single-bed temperature rise of hydrocracking reactor 7 ≤ 28 ℃, cold hydrogen valve opening ≤ 65%, liquid levels in high and low separation tanks, stripping tower, and fractionation tower 9 controlled at 55%, and outlet temperature of fractionation feed heater 8 controlled at 360 ℃.

[0055] Adjust the refining reaction temperature and cracking reaction temperature appropriately to stabilize the reaction depth, maintain the heavy naphtha yield at 36%, and operate stably for 24 hours.

[0056] The amount of hydrotreated diesel fuel blended with residual oil was increased by 5t / h. As the amount of hydrotreated diesel fuel feed increased, the amount of vacuum wax oil feed was reduced simultaneously to keep the total feed of the unit constant at 140t / h.

[0057] After the unit is blended with 30 t / h of hydrotreated diesel fuel, the operating conditions are controlled as follows: reaction pressure 14.7 MPa, average refining reaction temperature 360 ​​℃, average cracking reaction temperature 355.4 ℃, hydrogen-to-oil volume ratio 120:1, single-bed temperature rise of hydrorefining reactor 6 ≤ 42 ℃, single-bed temperature rise of hydrocracking reactor 7 ≤ 28 ℃, cold hydrogen valve opening ≤ 65%, liquid levels in high and low separation tanks, stripping tower, and fractionation tower 9 controlled at 55%, and outlet temperature of fractionation feed heater 8 controlled at 360 ℃.

[0058] Adjusting the refining and cracking reaction temperatures appropriately stabilizes the reaction depth (reference hydrogen consumption per ton of oil: 330–345 Nm). 3 / h), maintaining the naphtha yield at 33%-37%.

[0059] During the blending process, the speed of the circulating hydrogen generator is gradually adjusted to 7700rpm~8200rpm based on the bed temperature rise and the opening of the cold hydrogen valve to ensure the cold hydrogen capacity and a suitable hydrogen-to-oil ratio (1137~1400Nm). 3 / m 3 The opening of the cold hydrogen valve in the cracking reactor must not exceed 65% under any circumstances.

[0060] (5) After the blended residue oil and hydrogenated diesel are stabilized, the raw materials and products are sampled and analyzed, and data is collected;

[0061] The material balance and energy consumption of the equipment are statistically analyzed, and the process parameters are fine-tuned according to the product distribution.

[0062] Raw material changes The properties of hydrogenated diesel fuel from residual oil are shown in Table 1. Table 1 Properties of Hydrogenated Diesel Oil from Residue After the hydrocracking unit blends residue oil with hydrodiesel, the distillation range, sulfur, and nitrogen of the mixed feedstock decrease slightly, while other parameters remain largely unchanged, meeting the feedstock requirements of the hydrocracking unit. See Table 2 for details.

[0063] Table 2. Changes in the properties of the mixed feedstock oils Process parameters After the hydrocracking unit blends residue oil with hydrodiesel, the temperature rise of the refining bed decreases due to the reduction in sulfur and nitrogen content in the feedstock. Therefore, the inlet temperature of the refining bed is appropriately increased to ensure that the average refining reaction temperature remains basically unchanged.

[0064] To ensure an appropriate yield of diesel products, the temperature of the cracking catalyst bed was reduced;

[0065] Due to changes in raw materials and reaction depth, the consumption of new hydrogen decreased by 4400 Nm. 3 The process parameters change per hour, as shown in Table 3: Table 3 Main process parameters of the unit Comparative Example 1 The original design for hydrogenated diesel fuel was to process it in a diesel hydrotreating unit in order to remove sulfur and nitrogen and increase the cetane number of the diesel fuel.

[0066] Table 4 shows a comparison of key data between hydrocracking units and diesel hydrotreating units: Table 4 Comparison of key data between hydrocracking and diesel hydrotreating units Example 1

[0067] Product distribution: The yields of each product in the hydrocracking unit after blending residue oil with hydrodiesel are shown in Table 5. Table 5 Comparison of Product Yields from Residue Hydrogenation Diesel Units Due to the impact of the pandemic, the consumption of jet fuel products has dropped significantly. The final boiling point of jet fuel products in hydrocracking units has been controlled from around 250°C to around 230°C. This has resulted in some jet fuel components being forced into diesel products, leading to a jet fuel yield lower than the design value and a diesel yield higher than the design value.

[0068] Meanwhile, due to the high cetane number and good product quality of the hydrocracking unit, the company ensured an appropriate diesel yield and appropriately reduced the depth of cracking reaction according to its production needs. This resulted in a 4.22% increase in diesel yield, a 3.09% decrease in heavy naphtha yield, a 1.52% decrease in light naphtha yield, a 0.83% decrease in LPG yield, and little change in the yields of other products.

[0069] After the hydrocracking unit processes the residue oil into hydrodiesel, the apparent conversion rate of the residue oil into hydrodiesel is 67.11% (conversion rate = 1 - diesel unconverted rate = 1 - diesel yield), which means that most of the residue oil hydrodiesel is converted into non-diesel components.

[0070] Given the flexibility of hydrocracking units, the reaction temperature has considerable room for adjustment, and the yields of diesel and naphtha can be adjusted and optimized according to the company's production and operation.

[0071] Product quality: During the processing of hydrogenated diesel fuel from residual oil, the main indicators examined were cetane number, sulfur, and nitrogen content. Specific data are shown in Table 6. Table 6 Product Quality Comparison Because hydrotreated diesel fuel contains a large amount of alkanes and monocyclic cycloalkanes, the cetane number of diesel fuel does not change much before and after blending hydrotreated diesel fuel in the hydrocracking unit, but it is significantly improved compared to the design value of 44.5 for diesel fuel in the hydroreforming unit.

[0072] Compared to the cetane number of 40.8 for hydrotreated diesel fuel (see Table 1), the cetane number increased by 21.9 units.

[0073] Before and after hydrocracking of residue oil in the hydrocracking unit, the sulfur and nitrogen contents of the diesel products were 1.3 mg / kg and <0.3 mg / kg, respectively, but this was significantly higher than the sulfur content of 1.8 mg / kg in the diesel products from the diesel hydrotreating unit.

[0074] The aromatic potential of heavy naphtha increased from 33.6 to 35.8. The main reason is that during the refining of residue oil into hydrogenated diesel, the temperature of the cracking bed was reduced to ensure an appropriate yield of diesel products. The reduced temperature is not conducive to the saturation of aromatics and the ring-opening and chain-breaking reactions, which leads to an increase in the aromatic potential of heavy naphtha.

[0075] Unit energy consumption: Before and after the hydrocracking unit was blended with residue oil and hydrodiesel, the unit energy consumption decreased by 1.47 kgEO / t. The main reasons are the decrease in sulfur and nitrogen content of the feedstock, the decrease in temperature rise of the refining bed, the decrease in cold hydrogen, and the decrease in steam consumption of the circulating hydrogen compressor by 1.39 kgEO / t.

[0076] The yield of light components such as light and heavy naphtha decreased, which reduced the top load of the fractionation system and reduced the consumption of air and water cooling.

[0077] The decrease in new hydrogen consumption has led to a reduction in the power consumption of the new hydrogen compressor.

[0078] The energy consumption of the device is shown in Table 7.

[0079] Table 7. Changes in device energy consumption By comparing the comparative examples and the implementation examples, it can be seen that: (1) After processing the residue into hydrodiesel by the hydrocracking unit, the yield of light naphtha + heavy naphtha was 38.13%, which was 21.72% higher than the yield of hydrotreated naphtha of 16.41%.

[0080] The apparent conversion rate of hydrogenated residue diesel is 67.11% (conversion rate = 1 - diesel unconverted rate = 1 - diesel yield). Apparently, most of the hydrogenated residue diesel components are converted into non-diesel components, effectively reducing the diesel component and optimizing the product structure.

[0081] (2) After the hydrocracking unit processes the residue oil into hydrotreated diesel, the cetane number of the diesel product is 62.7, which is significantly higher than that of hydrotreated diesel, which has a cetane number of 44.5.

[0082] Compared to the cetane number of 40.8 for hydrotreated diesel fuel (see Table 1), the cetane number increased by 21.9 units.

[0083] Before and after hydrocracking of residue oil in the hydrocracking unit, the sulfur and nitrogen contents of the diesel products were 1.3 mg / kg and <0.3 mg / kg, respectively, which is a certain increase compared with the sulfur content of 1.8 mg / kg in the diesel products from the diesel hydrotreating unit.

[0084] The aromatic potential of heavy naphtha increased by 2.2 units.

[0085] Using hydrotreated diesel fuel as feedstock for hydrocracking units is beneficial for increasing the cetane number of diesel fuel throughout the plant, improving the feed properties of reforming units, and enhancing the overall product quality of the plant. Example 2

[0086] According to the company's production needs, the hydrocracking unit processes residue hydrotreated diesel under high load conditions (95% load). The total feed of the unit is 240 t / h, of which 30 t / h is residue hydrotreated diesel, with a blending ratio of 12.5%.

[0087] The operating conditions are as follows: reaction pressure 14.7 MPa, refining reaction temperature 377℃, cracking reaction temperature 380℃, hydrogen-to-oil volume ratio 1250, temperature rise of a single bed in the refining reactor ≤42℃, temperature rise of a single bed in the cracking reactor ≤28℃, cold hydrogen valve opening ≤65%, liquid levels in the high and low separation tanks, stripping tower, and fractionation tower controlled at 55%, and outlet temperature of the fractionation feed heater controlled at 363℃.

[0088] The yields of various products from the hydrocracking unit after blending residue oil with hydrodiesel are shown in Table 8. Table 8 Product Yields of Hydrogenated Diesel Unit for Residue Blending After the hydrocracking unit processes the residue oil into hydrodiesel, the apparent conversion rate of the residue oil into hydrodiesel is 69.09% (conversion rate = 1 - diesel unconverted rate = 1 - diesel yield). Apparently, most of the residue oil hydrodiesel components are converted into non-diesel components, effectively reducing the diesel component.

[0089] Given the flexibility of hydrocracking unit production, there is still considerable room for adjustment in reaction temperature and product yield. The yields of diesel and naphtha can be adjusted and optimized according to the company's production and operation situation to further increase the conversion rate of hydrotreated diesel from residue.

[0090] During the processing of hydrogenated diesel fuel from residual oil, the main indicators examined included cetane number, sulfur, and nitrogen content. Specific data are shown in Table 9. Table 9 Product Quality Comparison Before and after the hydrocracking unit blended residue oil with hydrogenated diesel, the cetane number of the diesel product was 61.9, which is a significant improvement compared to the diesel hydrotreating unit.

[0091] The sulfur and nitrogen content of the diesel product is 1.6 mg / kg and <0.3 mg / kg, respectively, but this is a certain increase compared to the sulfur content of 1.8 mg / kg in the diesel product from the diesel hydrotreating unit.

[0092] The cetane number of the diesel product decreased slightly compared to Example 1, while the sulfur content increased slightly, mainly due to the high unit load, but it showed some improvement compared to the diesel hydrotreating unit.

Claims

1. A method for processing hydrogenated diesel fuel from residual oil, characterized in that: This method employs hydrocracking technology, using hydrotreated diesel fuel (1) as feedstock for the hydrocracking unit. The hydrotreated diesel fuel (1) enters the intermediate diesel component tank area, and then enters the hydrocracking unit through the start-up diesel pipeline. Together with vacuum wax oil (2), it enters the feedstock buffer tank (3) as feedstock for the hydrocracking unit. The blending ratio of hydrotreated diesel fuel is 21.4%. The feedstock is pressurized to 18.0 MPa by the reaction feed pump (4) and then mixed with circulating hydrogen. The hydrogen-to-oil ratio is greater than 1137. After the furnace (5) is heated to 350-370°C, it enters the hydrorefining reactor (6) for desulfurization, denitrification and dearomatics reaction, with a refining reaction temperature of 350-390°C; then it enters the hydrocracking reactor (7) for cracking reaction, with a cracking reaction temperature of 350-400°C; after the reaction products are separated into gas and liquid by the high and low pressure separator and the stripping tower, the bottom oil of the stripping tower is heated to 350-370°C by the fractionation feed heater (8) and then enters the fractionation tower (9) for separation to produce naphtha (10), jet fuel (11) and diesel (12) products; The hydrocracking unit is a light oil type hydrocracking unit, which consists of reaction, fractionation, desulfurization and utility engineering sections. It adopts a one-stage full-cycle hydrocracking process. The unit uses vacuum wax oil (2) as the main raw material. The hydrorefining catalyst is HYT-6219-1.3T or KF-848-1.3Q, and the hydrocracking catalyst is HC-24L or HC-120. The operating pressure is 14.7 MPa. The products are crude liquefied petroleum gas, light naphtha, heavy naphtha, aviation kerosene and diesel oil. The cetane number index is ≥60.

2. The method for processing hydrogenated diesel oil from residual oil as described in claim 1, characterized in that: The aforementioned hydrogenated diesel oil (1) is one of the products of a fixed-bed hydrogenation unit for residue oil and belongs to diesel oil components.

3. The method for processing hydrotreated diesel oil from residual oil as described in claim 1, characterized in that: After being processed by a hydrocracking unit, the hydrotreated diesel fuel (1) is mostly converted into non-diesel components, including naphtha, jet fuel, and liquefied petroleum gas.

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