An improved process system and method for the hydrocracking reaction of wax oil.

Abstract

This invention belongs to the field of wax oil hydrocracking reaction. It is a process and method for modifying the product distribution of a wax oil hydrocracking unit by utilizing diesel products from residue hydrocracking. The feedstock in the first stage is pressurized by a first-stage feed pump and mixed with hydrogen. After being heated to the reaction temperature, it enters a first-stage refining reactor and a first-stage cracking reactor for reaction. The first-stage reaction products undergo gas-liquid separation through a fractionation system. The supervaporized oil and unconverted oil remaining after fractionation are used as feedstock for the second-stage reactor. This feedstock is mixed with high-NOx diesel as the second-stage feedstock, pressurized by a second-stage feed pump, mixed with hydrogen, heated to the reaction temperature, and then enters the second-stage cracking reactor for reaction. The second-stage reaction products undergo gas-liquid separation through a fractionation system. This invention involves blending a small amount of high-NOx diesel produced from a residue hydrocracking unit into the second-stage feedstock of a two-stage full-cycle wax oil hydrocracking unit. This passivates the activity of the second-stage cracking catalyst, improves catalyst selectivity, reduces LPG yield, and increases the C5 content of the product. + Liquid yield.

Description

Technical Field

[0001] This invention belongs to the field of wax oil hydrocracking reaction. Specifically, it is a process and method for changing the product distribution of a wax oil hydrocracking unit by utilizing diesel products from residue oil hydrocracking. Background Technology

[0002] The two-stage full-cycle wax oil hydrocracking unit has a high catalyst activity in the second-stage cracking reactor, resulting in intense secondary side reactions and a liquefied gas yield as high as 11.18%, which is 6.38% higher than the design value. In order to improve the product distribution of the unit and increase its operating economic efficiency, a process and method are proposed to change the product distribution of the wax oil hydrocracking unit by using diesel products from residue oil hydrocracking. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an improved process for the hydrocracking of wax oil. This process involves injecting high-NOx diesel fuel from a residue hydrocracking unit into the inlet of the second-stage cracking reactor. This process inhibits the activity of the second-stage cracking catalyst, improves catalyst selectivity, reduces secondary side reactions, alters the product distribution of the hydrocracking reaction, and increases the C5 content of the product. + Liquid yield.

[0004] To achieve the above objectives, the technical solution adopted in this invention is as follows: an improved process for the hydrocracking reaction of wax oil, wherein the feedstock oil is pressurized by a first-stage feed pump and mixed with hydrogen, heated to the reaction temperature, and then enters a first-stage refining reactor and a first-stage cracking reactor for reaction. The reaction products of the first stage are separated into gas and liquid by a fractionation system. The supervaporized oil and unconverted oil after fractionation are used as feedstock for the second-stage reactor, mixed with high-nitrogen diesel oil as feedstock oil for the second stage, and then pressurized by a second-stage feed pump and mixed with hydrogen, heated to the reaction temperature, and then enters the second-stage cracking reactor for reaction. The reaction products of the second stage are separated into gas and liquid by a fractionation system.

[0005] Based on the above technical solution, the first-stage refining reactor is filled with protective agents and refining catalysts, mainly for demetallization, desulfurization, denitrification, deoxygenation, and olefin saturation of the feedstock oil. The first-stage cracking reactor is filled with cracking catalysts, mainly for cracking reactions that reduce the size of large feedstock oil molecules. The second-stage cracking reactor is filled with a small amount of protective agents and refining agents, mainly for demetallization, desulfurization, denitrification, deoxygenation, and olefin saturation of the feedstock oil; the majority of the reactor is cracking catalysts, mainly for cracking reactions that reduce the size of large feedstock oil molecules.

[0006] Furthermore, the feedstock oil consists of wax oil products from an atmospheric and vacuum distillation unit, wax oil products from a residue hydrocracking unit, and deasphalted oil products from a solvent deasphalting unit; the ratio of the three is 42.11%:32.29%:25.6%.

[0007] Furthermore, the high-nitrogen diesel is high-nitrogen diesel produced by a residue hydrocracking unit, and the high-nitrogen diesel is a diesel fraction with a nitrogen content of up to 1000 ppm or more.

[0008] Furthermore, the fractionation system adopts a process of desulfurization stripping tower plus atmospheric fractionation tower. The desulfurization stripping tower desulfurizes the bottom oil of the cold and hot low-separation oil and then heats it in the fractionation heater before it enters the atmospheric tower. Crude naphtha is separated from the top of the atmospheric tower. The atmospheric tower is equipped with three side stripping towers for light fuel oil, white oil, and supervaporized oil. The light fuel oil and white oil are stripped by the side stripping towers and then sent out of the unit. The supervaporized oil and the unconverted oil at the bottom of the atmospheric tower are used as feedstock for the second-stage reactor.

[0009] Based on the above technical solution, the desulfurization stripping tower is located at the front. The reaction-generated oil can be stripped of hydrogen sulfide gas and some light hydrocarbons from the top of the tower through the desulfurization stripping tower. The bottom oil of the desulfurization stripping tower is heated by a heater and then enters an atmospheric distillation tower to separate crude naphtha, light fuel oil, white oil, supervaporized oil and unconverted oil according to the distillation range.

[0010] Furthermore, the ratio of the supervaporized oil, unconverted oil, and high-nitrogen diesel is 37.75:37.75:1 to 14:14:1.

[0011] Based on the above technical solution, the supervaporized oil and unconverted oil used as feedstock for the second-stage reactor are waxy oil fractions with temperatures above 360°C that have not undergone conversion after the first-stage feedstock has passed through the reactor. The second-stage feedstock includes supervaporized oil, unconverted oil, and high-nitrogen diesel oil.

[0012] Furthermore, the reaction temperature for the first stage is 385-420℃, and the reaction temperature for the second stage is 340-395℃.

[0013] An improved process system for the hydrocracking reaction of wax oil includes a primary reaction system, a secondary reaction system, and a fractionation system. The primary feed tank is connected to the inlet of the primary reaction system, and the outlet of the primary reaction system is connected to the inlet of a hot high-pressure separator. The secondary feed tank and a high-NOx diesel tank are connected to the inlet of the secondary reaction system, and the outlet of the secondary reaction system is connected to the inlet of the hot high-pressure separator. The outlet of the hot high-pressure separator is connected to the fractionation system, and the overvaporized oil side line and the unconverted oil outlet line of the fractionation system are connected to the secondary feed tank.

[0014] Furthermore, the first-stage reaction system includes a first-stage refining reactor and a first-stage cracking reactor, which are connected in series. A first-stage feed tank is connected in sequence to a first-stage feed pump, a first-stage feed / reaction product heat exchanger, a first-stage heater, a first-stage refining reactor, and a first-stage cracking reactor via pipelines. The outlet material of the first-stage cracking reactor is connected to a high-pressure thermal separator after heat exchange in the first-stage feed / reaction product heat exchanger.

[0015] Furthermore, the two-stage reaction system includes a two-stage cracking reactor. The high-nitrogen diesel tank is connected to the inlet of the two-stage feed pump via a reciprocating pump. The material in the two-stage feed tank and the high-nitrogen diesel are connected to the two-stage cracking reactor via the two-stage feed pump, the two-stage feed / reaction product heat exchanger, and the two-stage heater. The outlet material of the two-stage cracking reactor is connected to the hot high-pressure separator after heat exchange in the two-stage feed / reaction product heat exchanger.

[0016] Furthermore, the first-stage refining reactor is equipped with four refining beds, the first-stage cracking reactor is equipped with one refining bed and two cracking beds, and the second-stage cracking reactor is equipped with three cracking beds.

[0017] Furthermore, the fractionation system includes a desulfurized hydrogen stripping tower and an atmospheric fractionation tower. The outlet of the hot high-pressure separator is connected to the desulfurized hydrogen stripping tower. The bottom outlet of the desulfurized hydrogen stripping tower is connected to the inlet of the atmospheric fractionation tower via a bottom pump, a bottom heat exchanger, and a fractionation heater. The bottom outlet of the atmospheric fractionation tower is connected to the unconverted oil outlet device after being pressurized by an outlet pump through an unconverted oil outlet pipeline. The unconverted oil outlet pipeline is connected to the second-stage feed tank via a circulation pipeline after the outlet pump.

[0018] Furthermore, crude naphtha is separated at the top of the atmospheric distillation tower and sequentially connected to a naphtha stabilization tower and a naphtha separation tower. The naphtha separation tower is connected to a light naphtha outlet device and a heavy naphtha outlet device, respectively. The atmospheric distillation tower is equipped with a light fuel oil side stream, a white oil side stream, and a supervaporized oil side stream. The light fuel oil side stream is connected to the light fuel oil outlet device, the white oil side stream is connected to the white oil outlet device, and the supervaporized oil side stream is connected to the second-stage feed tank through a circulation pipeline.

[0019] Furthermore, the system also includes a circulating hydrogen compressor, which is connected to a first-stage reaction system and a second-stage reaction system via a circulating hydrogen line.

[0020] The beneficial effects of this invention are as follows: This invention involves blending a small amount of high-nitrogen diesel produced by a residue hydrocracking unit into the second-stage feedstock of a two-stage full-cycle wax oil hydrocracking unit. The high-nitrogen diesel deactivates the second-stage cracking catalyst, improving catalyst selectivity, reducing LPG yield, and increasing the C5 of the product. + Liquid yield. Attached Figure Description

[0021] Figure 1 This is a flow chart of the wax oil hydrocracking reaction process system of the present invention;

[0022] Figure 2 A trend chart of low-separation gas and liquefied gas yields;

[0023] Figure 3 A trend chart showing the yield of light and heavy naphtha;

[0024] Figure 4 A trend chart of light fuel oil yield;

[0025] Figure 5 C5 + Liquid product yield trend chart;

[0026] Figure 6 This is a diagram of the inlet temperature of a cracking bed.

[0027] Figure 7 This is a temperature rise diagram of a cracking catalyst bed.

[0028] Figure 8 This is a WABT temperature diagram of a section of a cracking catalyst bed;

[0029] Figure 9 This is a temperature rise diagram of the catalyst bed in the second stage of cracking;

[0030] Figure 10 This is a diagram showing the inlet temperature of the two-stage cracking bed.

[0031] Figure 11 This is a WABT temperature diagram of the two-stage cracking catalyst bed;

[0032] In the diagram: 1. First-stage refining reactor; 2. First-stage cracking reactor; 3. Second-stage cracking reactor; 4. First-stage feed tank; 5. Second-stage feed tank; 6. High-NOx diesel tank; 7. First-stage feed pump; 8. First-stage feed / reaction product heat exchanger; 9. First-stage heater; 10. Reciprocating pump; 11. Second-stage feed pump; 12. Second-stage feed / reaction product heat exchanger; 13. Second-stage heater; 14. Desulfurized hydrogen stripping tower; 15. Atmospheric distillation tower; 16. Bottom pump; 17. Bottom heat exchanger; 18. Distillation heater; 19. 20. Unconverted oil outlet pipeline, 21. Outlet pump, 22. Circulation pipeline, 23. Naphtha stabilizer tower, 24. Naphtha separator, 25. Light fuel oil side line, 26. White oil side line, 27. Supervaporized oil side line, 28. Circulating hydrogen compressor, 29. Circulating hydrogen line, 30. Hot high-pressure separator, 31. Hot low-pressure separator; A. Light fuel oil outlet unit, B. White oil outlet unit, C. Unconverted oil outlet unit, D. Light naphtha outlet unit, E. Heavy naphtha outlet unit, F. LPG to light hydrocarbon recovery, G. Primary feedstock. Detailed Implementation

[0033] To make the structure and function of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0034] The two-stage full-cycle wax oil hydrocracking unit exhibits high catalyst activity in the second-stage cracking reactor, leading to severe secondary side reactions and a liquefied petroleum gas (LPG) yield as high as 11.18%, exceeding the design value by 6.38%. To improve the unit's product distribution and operational efficiency, high-NOx diesel fuel produced from the residue hydrocracking unit is injected into the inlet of the second-stage cracking reactor. This process suppresses catalyst activity, improves catalyst selectivity, reduces secondary side reactions, alters the hydrocracking product distribution, and increases the C5 content of the product. + Liquid yield.

[0035] Currently, the main purpose of blending coking cracked diesel or catalytic cracked diesel in wax oil hydrocracking units is to reduce the diesel-to-gasoline ratio in refineries and increase the added value of catalytic cracked diesel. Two-stage hydrocracking units do not utilize high-nitrogen-content diesel to significantly improve the product distribution of the unit.

[0036] This invention involves blending a small amount of high-NOx diesel produced from a residue hydrocracking unit into the second-stage feedstock of a two-stage full-cycle wax oil hydrocracking unit. The high-NOx diesel deactivates the second-stage cracking catalyst, improving catalyst selectivity, reducing LPG yield, and increasing the product's C5 content. + Liquid yield.

[0037] For detailed processes, please refer to the appendix. Figure 1 An improved process system for the hydrocracking reaction of wax oil includes a primary reaction system, a secondary reaction system, and a fractionation system. A primary feedstock tank 4 is connected to the inlet of the primary reaction system, and the outlet of the primary reaction system is connected to the inlet of a high-pressure separator. A secondary feedstock tank 5 and a high-nitrogen diesel tank 6 are connected to the inlet of the secondary reaction system, and the outlet of the secondary reaction system is connected to the inlet of the high-pressure separator. The outlet of the high-pressure separator is connected to the fractionation system, and the overvaporized oil side line and unconverted oil outlet line of the fractionation system are connected to the secondary feedstock tank. The system also includes a circulating hydrogen compressor 27, which is connected to the primary and secondary reaction systems via a circulating hydrogen line 28.

[0038] Further, the first-stage reaction system includes a first-stage refining reactor 1 and a first-stage cracking reactor 2, which are connected in series. A first-stage feed tank 4 is connected sequentially via pipelines to a first-stage feed pump 7, a first-stage feed / reaction product heat exchanger 8, a first-stage heater 9, the first-stage refining reactor, and the first-stage cracking reactor 2. The outlet material of the first-stage cracking reactor 2 is connected to a high-pressure separator after heat exchange in the first-stage feed / reaction product heat exchanger 8. The second-stage reaction system includes a second-stage cracking reactor 3, high-nitrogen diesel... Oil tank 6 is connected to the inlet of the second-stage feed pump via reciprocating pump 10. The material in the second-stage feed tank 5 and the high-nitrogen diesel oil are connected to the second-stage cracking reactor 3 via the second-stage feed pump 11, the second-stage feed / reaction product heat exchanger 12, and the second-stage heater 13. The outlet material of the second-stage cracking reactor 3 is connected to the hot high-pressure separator after heat exchange in the second-stage feed / reaction product heat exchanger 12. The first-stage refining reactor 1 is equipped with four refining beds, the first-stage cracking reactor 2 is equipped with one refining bed and two cracking beds, and the second-stage cracking reactor 3 is equipped with three cracking beds.

[0039] Based on the above technical solution, the first-stage refining reactor is filled with protective agents and refining catalysts, mainly for demetallization, desulfurization, denitrification, deoxygenation, and olefin saturation of the feedstock oil. The first-stage cracking reactor is filled with cracking catalysts, mainly for cracking reactions that reduce the size of large feedstock oil molecules. The second-stage cracking reactor is filled with a small amount of protective agents and refining agents, mainly for demetallization, desulfurization, denitrification, deoxygenation, and olefin saturation of the feedstock oil; the majority of the reactor is cracking catalysts, mainly for cracking reactions that reduce the size of large feedstock oil molecules.

[0040] Further, the fractionation system includes a desulfurization stripping tower 14 and an atmospheric fractionation tower 15. The outlet of the hot high-pressure separator is connected to the desulfurization stripping tower 14. The bottom outlet of the desulfurization stripping tower 14 is connected to the inlet of the atmospheric fractionation tower 15 via a bottom pump 16, a bottom heat exchanger 17, and a fractionation heater 18. The bottom outlet of the atmospheric fractionation tower 15 is connected to the unconverted oil outlet device via an unconverted oil outlet pipeline 19, pressurized by an outlet pump 20. The unconverted oil outlet pipeline 19 is connected to the secondary unconverted oil outlet device via a circulation pipeline 21 after the outlet pump 20. The first-stage feedstock tank 5; the atmospheric distillation tower 15 separates crude naphtha at the top and is sequentially connected to the naphtha stabilization tower 22 and the naphtha separation tower 23. The naphtha separation tower 23 is connected to the light naphtha outlet device and the heavy naphtha outlet device respectively; the atmospheric distillation tower 15 is provided with a light fuel oil side stream 24, a white oil side stream 25 and a supervaporized oil side stream 26. The light fuel oil side stream 24 is connected to the light fuel oil outlet device, the white oil side stream 25 is connected to the white oil outlet device, and the supervaporized oil side stream 26 is connected to the second-stage feedstock tank 5 through the circulation pipeline 21.

[0041] Based on the above technical solution, the desulfurization stripping tower is located at the front. The reaction-generated oil can be stripped of hydrogen sulfide gas and some light hydrocarbons from the top of the tower through the desulfurization stripping tower. The bottom oil of the desulfurization stripping tower is heated by a heater and then enters an atmospheric distillation tower to separate crude naphtha, light fuel oil, white oil, supervaporized oil and unconverted oil according to the distillation range.

[0042] Furthermore, the reaction products from the second-stage reactor enter the hot high-pressure separator 29 after heat exchange in the second-stage feed / reaction product heat exchangers E107 and E109. After gas-liquid separation in the hot high-pressure separator 29, the hot high-pressure oil enters the hot low-pressure separator 30. After gas-liquid separation again in the hot low-pressure separator 30, the hot low-pressure oil enters the desulfurization stripping tower 14.

[0043] The working process of this system is as follows:

[0044] 1. This unit adopts a two-stage full-cycle hydrocracking process. The feedstock is pressurized by the feed pump 7 and mixed with hydrogen. It is then heated by the feed / reaction product heat exchanger 8 and heated to the required reaction temperature by the furnace 9 before entering the refining reactor 1 and the cracking reactor 2. The reaction products are cooled by heat exchange with the feedstock and then enter the hot high-pressure separator.

[0045] 2. The supervaporized oil and unconverted oil from the second-stage feedstock separation system are mixed and fed into the second-stage feedstock tank 5. After being pressurized by the second-stage feed pump 11, they are mixed with hydrogen and then heat-exchanged by the second-stage feedstock / reaction product heat exchanger 12. After being heated to the required reaction temperature by the second-stage heater 13, they enter the second-stage cracking reactor 3. After the reaction products are cooled by heat exchange with the second-stage feedstock, they enter the hot high-pressure separator.

[0046] 3. The high-nitrogen diesel produced by the fluidized bed residue hydrocracking unit is pressurized by reciprocating pump 10 and then enters the inlet of the second-stage feed pump 11 to mix with the second-stage feedstock oil and enter the second-stage cracking reactor 3 for reaction.

[0047] The process of this invention is still as follows: the first-stage feedstock oil is pressurized by a first-stage feed pump and mixed with hydrogen. After being heated to the reaction temperature, it enters a first-stage refining reactor and a first-stage cracking reactor for reaction. The first-stage reaction products are separated into gas and liquid by a fractionation system. The supervaporized oil and unconverted oil after fractionation are used as feedstock for the second-stage reactor and mixed with high-nitrogen diesel oil as the second-stage feedstock oil. After being pressurized by a second-stage feed pump and mixed with hydrogen, it enters a second-stage cracking reactor for reaction. The second-stage reaction products are separated into gas and liquid by a fractionation system.

[0048] Furthermore, the feedstock oil consists of wax oil products from an atmospheric and vacuum distillation unit, wax oil products from a residue hydrocracking unit, and deasphalted oil products from a solvent deasphalting unit; the ratio of the three is 42.11%:32.29%:25.6%.

[0049] Furthermore, the high-nitrogen diesel is high-nitrogen diesel produced by a residue hydrocracking unit, and the high-nitrogen diesel is a diesel fraction with a nitrogen content of up to 1000 ppm or more.

[0050] Furthermore, the fractionation system adopts a process of desulfurization stripping tower plus atmospheric fractionation tower. The desulfurization stripping tower desulfurizes the bottom oil of the cold and hot low-separation oil and then heats it in the fractionation heater before it enters the atmospheric tower. Crude naphtha is separated from the top of the atmospheric tower. The atmospheric tower is equipped with three side stripping towers for light fuel oil, white oil, and supervaporized oil. The light fuel oil and white oil are stripped by the side stripping towers and then sent out of the unit. The supervaporized oil and the unconverted oil at the bottom of the atmospheric tower are used as feedstock for the second-stage reactor.

[0051] Furthermore, the ratio of supervaporized oil, unconverted oil, and high-nitrogen diesel is 37.75:37.75:1 to 14:14:1.

[0052] Based on the above technical solution, the supervaporized oil and unconverted oil used as feedstock for the second-stage reactor are waxy oil fractions with temperatures above 360°C that have not undergone conversion after the first-stage feedstock has passed through the reactor. The second-stage feedstock includes supervaporized oil, unconverted oil, and high-nitrogen diesel oil.

[0053] Furthermore, the reaction temperature for the first stage is 385-420℃, and the reaction temperature for the second stage is 340-395℃.

[0054] The mixed wax oil hydrocracking unit of this invention uses wax oil products from an atmospheric and vacuum distillation unit, wax oil products from a residue hydrocracking unit, and deasphalted oil products from a solvent deasphalting unit as raw materials, with a designed processing ratio of 42.11%:32.29%:25.6%. The reaction section adopts a two-stage full-cycle process. The first stage reaction has two reactors connected in series, the first stage refining reactor has four refining beds, and the first stage refining / cracking reactor has one refining bed and two cracking beds. The second stage cracking reactor has three cracking beds. The fractionation system adopts a main stripping tower plus an atmospheric tower process. The main stripping tower heats the bottom oil after desulfurization of cold and hot low-fraction oil in a fractionation heater before feeding it into the atmospheric tower. Crude naphtha is separated at the top of the atmospheric tower. The atmospheric tower has three side-stream stripping towers for light fuel oil, white oil, and supervaporized oil. The light fuel oil and white oil are stripped through the side-stream towers and then sent out of the unit. The supervaporized oil and unconverted oil from the bottom of the atmospheric tower are used as feedstock for the second stage reactor.

[0055] This invention explores ways to change the product distribution of a wax oil hydrocracking unit and improve the unit's C5. + A method for liquid yield is proposed. A small amount of high-NOx diesel oil produced by a residue hydrocracking unit is added to the feed of the two-stage cracking reactor. Hydrodenitrification occurs on the catalyst bed in the reactor, generating ammonia. The presence of a certain concentration of ammonia partial pressure in the reactor can inhibit the cracking activity of the hydrocracking catalyst, reduce the occurrence of secondary side reactions, and change the selectivity of the catalyst, thereby altering the product distribution.

[0056] The process and beneficial effects of this invention are explained below through specific experimental procedures:

[0057] Starting at 16:40 on February 13, 2023, 4 t / h of high-nitrogen diesel produced by the residue hydrocracking unit was added to the feed of the second-stage cracking reactor, and the addition was stopped at 12:00 on February 17.

[0058] The properties of a portion of the crude oil are shown in the table below:

[0059]

[0060] The properties of the second-stage feedstock oil are shown in the table below:

[0061] The reaction conditions are shown in the table below:

[0062] The properties of high-nitrogen diesel produced by residue hydrocracking are shown in the table below.

[0063]

[0064] The nitrogen content of the mixed feed after adding high-nitrogen diesel is calculated as follows:

[0065]

[0066] While maintaining a constant conversion rate in the primary cracking reactor, blending high-NOx diesel produced from the hydrocracking of fluidized bed residue oil into the secondary cracking reactor can improve product distribution and increase C5 content. + Product liquid yield.

[0067] (1) The yield of low-grade gas decreased by 0.07%, and the yield of liquefied petroleum gas (LPG) decreased by 2.26%; see also Figure 2 Trend chart of low-separation gas and liquefied gas yield.

[0068] (2) The yield of light naphtha increased by 0.59%, and the yield of heavy naphtha increased by 1.14%; see also Figure 3 Trend chart of light and heavy naphtha yield.

[0069] (3) The yield of light fuel oil increased by 0.63%; see also Figure 4 Light fuel oil yield trend chart.

[0070] (4)C5 + Liquid product yield increased by 2.04%; see also Figure 5 C5 + Liquid product yield trend chart.

[0071] According to the test data, the yield of liquefied petroleum gas (LPG) decreased by 2.26%, and the output decreased by 10 tons per hour. The yield of heavy naphtha increased by 1.14%, and the output increased by 7 tons per hour. Based on market prices of 4,000 yuan / ton for LPG and 7,000 yuan / ton for heavy naphtha, and with the unit operating at 100% processing load, it can generate approximately 78.84 million yuan in revenue for the company annually.

[0072] I. Test conditions for this invention:

[0073] (1) The feed rate of the first stage is 480t / h, and the feed rate of the second stage is 290t / h, which remains unchanged.

[0074] (2) The reaction temperature of the first stage of the refining catalyst and the cracking catalyst remains constant.

[0075] (3) To maintain the total conversion rate of the reaction, adjust the temperature of the two-stage cracking reactor.

[0076] (4) The high-nitrogen diesel fuel injection rate remains constant at 4t / h, and the flow rate can be accurately measured by a reciprocating pump.

[0077] (5) High-nitrogen diesel refueling time is from 16:40 on February 13, 2023 to 12:00 on February 17, 2023.

[0078] II. Reactor Temperature Control

[0079] (1) Control the inlet temperature of the first-stage cracking catalyst bed to 395.3℃, the temperature rise to 13.8℃, and the WABT temperature.

[0080] 402.2℃; the inlet temperature of the second bed is 390.1℃, with a temperature rise of 17.0℃, and the WABT temperature remains unchanged at 398.6℃. This is to eliminate the influence of the temperature change of the first-stage cracking catalyst on the product distribution. See [link / reference]. Figure 6 A section of the cracking bed inlet temperature diagram. Figure 7 Temperature rise diagram of a cracking catalyst bed Figure 8 WABT temperature diagram of a cracking catalyst bed.

[0081] (2) The blending of high-nitrogen diesel fuel inhibits the activity of the secondary cracking catalyst, resulting in a significant decrease in the temperature rise of the secondary cracking catalyst bed. The temperature rise of the first secondary cracking bed decreased by 3.52℃, the temperature rise of the second secondary cracking bed decreased by 1.88℃, and the temperature rise of the third secondary cracking bed decreased by 1.53℃. (See [reference needed]) Figure 9 Temperature rise diagram of the two-stage cracking catalyst bed.

[0082] (3) To maintain a constant overall conversion rate, the inlet temperature of the secondary cracking catalyst bed needs to be increased to raise the mass average temperature of each bed. The inlet temperature of the first secondary cracking bed is increased by 3.52℃, and the WABT temperature is increased by 3.39℃; the inlet temperature of the second secondary cracking bed is increased by 1.41℃, and the WABT temperature is increased...

[0083] 1.91℃; the inlet temperature of the second-stage cracking three-bed layer increased by 0.91℃, and the WABT temperature increased by 1.05℃. See [reference needed]. Figure 10 Inlet temperature diagram of the second-stage cracking bed and Figure 11 WABT temperature diagram of the two-stage cracking catalyst bed.

[0084] It should be noted that the parts of this invention not described in detail are prior art.

[0085] The above examples are merely preferred embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A process for improving the performance of a wax oil hydrocracking reaction, characterized by: The feedstock oil is pressurized by a first-stage feed pump and mixed with hydrogen. After being heated to the reaction temperature, it enters a first-stage refining reactor and a first-stage cracking reactor for reaction. The reaction products of the first stage are separated into gas and liquid by a fractionation system. The supervaporized oil and unconverted oil after fractionation are used as feedstock for the second-stage cracking reactor. They are mixed with high-nitrogen diesel oil as feedstock oil for the second stage. After being pressurized by a second-stage feed pump and mixed with hydrogen, it enters the second-stage cracking reactor for reaction. The reaction products of the second stage are separated into gas and liquid by the fractionation system. The feedstock oil in this section is wax oil product from atmospheric and vacuum distillation unit, wax oil product from residue hydrocracking unit, and deasphalted oil product from solvent deasphalting unit; The proportions of wax oil products from the atmospheric and vacuum distillation unit, wax oil products from the residue hydrocracking unit, and deasphalted oil products from the solvent deasphalting unit in the feedstock are 42.11%:32.29%:25.6%. The high-nitrogen diesel oil is produced by a residue hydrocracking unit; The fractionation system adopts a process of desulfurization stripping tower plus atmospheric fractionation tower. The desulfurization stripping tower desulfurizes the bottom oil of the cold and hot low-separation oil and then heats it in the fractionation heater before it enters the atmospheric tower. Crude naphtha is separated from the top of the atmospheric tower. The atmospheric tower is equipped with three side stripping towers for light fuel oil, white oil and supervaporized oil. The light fuel oil and white oil are stripped in the side stripping towers and then sent out of the unit. The supervaporized oil and the unconverted oil at the bottom of the atmospheric tower are used as feedstock for the second-stage cracking reactor after stripping. The ratio of supervaporized oil, unconverted oil and high-nitrogen diesel used as feedstock in the second stage is 37.75:37.75:1 to 14:14:

1. The nitrogen content of the high-nitrogen diesel oil is 863 mg / kg.

2. A process for improving the performance of a gas oil hydrocracking reaction according to claim 1, characterized in that: The reaction temperature for the first stage is 385-420℃, and the reaction temperature for the second stage is 340-395℃.

3. A process for improving the performance of a gas oil hydrocracking reaction according to claim 1 or 2, characterized in that: The process system employed in the method includes a primary reaction system, a secondary reaction system, and a fractionation system. The primary reaction system comprises a primary refining reactor and a primary cracking reactor. A primary feedstock tank is connected to the inlet of the primary reaction system, and the outlet of the primary reaction system is connected to the inlet of a high-pressure thermal separator. The secondary reaction system comprises a secondary cracking reactor. A secondary feedstock tank and a high-NOx diesel tank are connected to the inlet of the secondary reaction system, and the outlet of the secondary reaction system is connected to the inlet of the high-pressure thermal separator. The outlet of the high-pressure thermal separator is connected to the fractionation system, and the stripping tower for the vaporized oil side stream and the unconverted oil outlet pipeline of the fractionation system are connected to the secondary feedstock tank.

4. A process for improving the performance of a gas oil hydrocracking reaction according to claim 3, characterized in that: The first-stage reaction system includes a refining reactor and a cracking reactor connected in series. A feed tank is sequentially connected via pipelines to a feed pump, a feed / reaction product heat exchanger, a heater, the refining reactor, and the cracking reactor. The outlet material of the cracking reactor is connected to the high-pressure separator after heat exchange in the feed / reaction product heat exchanger. The second-stage reaction system includes a second-stage cracking reactor. A high-NOx diesel tank is connected to the inlet of the second-stage feed pump via a reciprocating pump. The material in the second-stage feed tank and the high-NOx diesel are connected to the second-stage cracking reactor via the feed pump, the feed / reaction product heat exchanger, and the heater. The outlet material of the second-stage cracking reactor is connected to the high-pressure separator after heat exchange in the feed / reaction product heat exchanger. The first-stage refining reactor has four refining beds, the first-stage cracking reactor has one refining bed and two cracking beds, and the second-stage cracking reactor has three cracking beds.

5. A process for improving the performance of a gas oil hydrocracking reaction according to claim 3, characterized in that: The fractionation system includes a desulfurization stripping tower and an atmospheric fractionation tower. The outlet of the hot high-pressure separator is connected to the desulfurization stripping tower. The bottom outlet of the desulfurization stripping tower is connected to the inlet of the atmospheric fractionation tower via a bottom pump, a bottom heat exchanger, and a fractionation heater. The bottom outlet of the atmospheric fractionation tower is connected to the unconverted oil outlet device via an unconverted oil outlet pipeline after being pressurized by an outlet pump. The unconverted oil outlet pipeline is connected to the second-stage feed tank via a circulation pipeline after the outlet pump. Crude naphtha is separated at the top of the atmospheric fractionation tower and sequentially connected to a naphtha stabilization tower and a naphtha separation tower. The naphtha separation tower is connected to a light naphtha outlet device and a heavy naphtha outlet device, respectively.

6. A process for improving the performance of a gas oil hydrocracking reaction according to claim 3, characterized in that: It also includes a circulating hydrogen compressor, which is connected to a first-stage reaction system and a second-stage reaction system via a circulating hydrogen line.

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