A method for combined hydrotreating and hydrocracking of light distillate oil with hydrogen supply

Abstract

The present disclosure relates to a method for combined hydrogen supply and hydrocracking treatment of light distillate oil. The method includes: mixing the light distillate oil with a hydrogen supply agent and then entering a hydrocracking unit to contact with a hydrocracking catalyst for a hydrocracking reaction to obtain a hydrocracking reaction product; feeding the hydrocracking reaction product into a separation unit for a first separation to obtain a hydrogen supply agent after hydrogen supply, a gas product, a liquid product, and unconverted oil; subjecting the hydrogen supply agent after hydrogen supply to a hydrogen supply agent regeneration treatment, mixing the excess hydrogen with fresh hydrogen, and then returning it to the hydrogen supply agent hydrogenation reactor; and returning the unconverted oil to the hydrocracking unit. By using the method of the present disclosure, coking can be reduced, the light oil yield can be increased, the reaction system pressure can be reduced, and the safety of the device can be improved; at the same time, the hydrogen supply agent after hydrogen supply can be recycled after restoring its hydrogen supply performance, which can effectively increase economic benefits.

Description

Technical Field

[0001] The present disclosure relates to the field of petrochemical industry, and particularly to a method for combined hydrogen supply and hydrocracking treatment of light distillate oil. Background Art

[0002] Petroleum resources in China are relatively scarce, and the demand for light crude oil in the petroleum refining process is relatively high. The cracking process of petroleum is mainly based on hydrocatalysis. The hydrocatalysis technology can increase the yield of light oil products, meet the market demand, improve the economic benefits of the petroleum industry in China, and at the same time minimize environmental pollution as much as possible.

[0003] At present, the hydrocracking process is widely used in desulfurization of oil products and lightening of oil products, but its reaction system has high pressure, high chemical hydrogen consumption, and high equipment investment. Therefore, reducing the pressure of the reaction system is of crucial significance for energy conservation and consumption reduction of the whole device.

[0004] In the hydrocracking process, the reaction system is in a high-pressure and hydrogen-rich state. Since the molecular weight of hydrogen is low, it is very easy to escape and leak, causing great safety risks. At the same time, under high-pressure conditions, the device has high equipment investment and high safety risks, which bring great troubles to the stable, safe and long-term operation of the existing hydrocracking process device.

[0005] CN1388219A discloses a catalytic conversion method for reducing the olefin content of gasoline by using a hydrogen supply component, which is characterized by applying a fluid catalytic cracking process to saturate light raw materials and improve product properties, but the fluid catalytic cracking reactor is not suitable for the hydrocracking process.

[0006] CN1393524A and CN105567319B respectively disclose a method for lightening heavy oil and a method for treating heavy oil, which are characterized by using distillate oil as a hydrogen donor, mixing with raw materials and catalysts under the action of hydrogen, and then performing high-pressure hydrotreating or hydrocracking, and the hydrogen donor is subjected to fixed-bed hydrogenation and recycled, which can treat heavy residue oil. However, hydrogen and the hydrogen donor participate in the reaction at the same time, the reaction pressure of the hydrogen-rich reaction is high, and the hydrogen donor is used as an additive or auxiliary agent, which is not conducive to energy conservation and consumption reduction of the device, and the device operation is difficult.

[0007] CN102504862A and CN105505449A respectively disclose a hydrogen supply thermal cracking method and a hydrogen supply coking method, which are characterized by using distillate oil as a hydrogen donor, mixing with heavy raw materials and heating to a relatively high temperature to thermally crack the raw materials, reduce the viscosity of the raw materials and reduce the coke yield. However, this method does not add a catalyst, the loss of the hydrogen donor is large during the thermal cracking process, and the efficiency is low.

[0008] In the prior art, hydrogen-donating thermal cracking has been widely applied in the visbreaking of crude oil. Common hydrogen donors include its own distillate oil, alcohols, formic acid and its salts, cyclohexene, hydrazine hydrate, triethylsilane, water, etc. The methods used include hydrogen-donating thermal cracking, microwave thermal cracking, hydrocracking, hydrofining, etc. Among them, for hydrocracking or hydrofining, external hydrogen needs to be introduced and the operation is carried out under hydrogenation conditions. The catalysts used are often solid catalysts, and fixed-bed reactors are adopted. The hydrogen donor uses its own distillate oil or is injected with chemicals at one time. The consumption of a large amount of chemicals and the recycling of a large amount of hydrogen lead to an increase in investment. The by-products of some hydrogen donors may be difficult to separate from the products, resulting in unqualified product indicators. Summary of the Invention

[0009] The object of the present disclosure is to provide a method for treating oil products to solve the problems of high reaction system pressure, low device safety, more coking and low light oil yield in the traditional process.

[0010] To achieve the above object, the present disclosure provides a method for combined hydrogen-donating hydrocracking treatment of light distillate oil, which includes: mixing the light distillate oil with a hydrogen donor and then entering a hydrocracking unit to contact with a hydrocracking catalyst for hydrocracking reaction to obtain a hydrocracking reaction product; entering the hydrocracking reaction product into a flash tank to obtain a gas product and a bottom oil of the flash tank, and performing a first separation on the bottom oil of the flash tank to obtain a hydrogen donor after hydrogen supply, a gas product, a liquid product and unconverted oil; mixing the hydrogen donor after hydrogen supply with fresh hydrogen and then entering a hydrogen donor hydrogenation reactor for hydrogen donor regeneration treatment, and then performing a second separation to obtain a hydrogen donor with restored hydrogen supply performance and excess hydrogen; mixing the excess hydrogen with the fresh hydrogen and then returning it to the hydrogen donor hydrogenation reactor; and returning the unconverted oil to the hydrocracking unit.

[0011] Optionally, the light distillate oil is selected from one or more of wax oil, diesel oil and kerosene.

[0012] Optionally, the hydrogen donor is selected from one or more of cyclohexane, cyclohexene, cyclohexadiene, methylcyclohexane and decalin, and preferably cyclohexane.

[0013] Optionally, the hydrocracking catalyst is selected from non-noble metal catalysts and / or noble metal catalysts; the non-noble metals in the non-noble metal catalysts are selected from one or more of nickel, molybdenum and chromium, and the noble metals in the noble metal catalysts are selected from one or more of platinum, palladium and rhodium; preferably a Ni-Mo series non-noble metal catalyst.

[0014] Optionally, the form of the reactor in the hydrocracking unit is one or more of a fixed-bed reactor, a fluidized-bed reactor and a moving-bed reactor, and preferably a fixed-bed reactor.

[0015] Optionally, the conditions for the hydrocracking reaction are as follows: the reaction temperature is 150 to 450 °C, preferably 420 to 430 °C; the reaction pressure is 5 to 100 bar, preferably 35 to 50 bar; the feed ratio of the light distillate oil to the hydrogen donor is 0.5 to 100:1% by weight, preferably 1 to 50% by weight.

[0016] Optionally, the method further includes, before the hydrocracking reaction, first mixing the light distillate oil and the hydrogen donor, and then heating to 150 to 450 °C, preferably 420 to 430 °C; increasing the pressure to 5 to 100 bar, preferably 35 to 50 bar.

[0017] Optionally, the temperature in the flash tank is 200 to 420 °C, and the pressure in the flash tank is 10 to 20 bar; the first separation is carried out in a distillation column; the fractionation cut-off point between the hydrogen donor after hydrogen supply and the liquid product is 130 to 160 °C; the fractionation cut-off point between the liquid product and the unconverted oil is 250 to 320 °C.

[0018] Optionally, the reaction conditions for the regeneration treatment of the hydrogen donor include: the reaction temperature is 150 to 300 °C, preferably 180 to 250 °C; the reaction pressure is 5 to 70 bar, preferably 20 to 35 bar; the mass ratio of the fresh hydrogen to the hydrogen donor after hydrogen supply is 0.01 to 0.08:1, preferably 0.03 to 0.05:1.

[0019] Optionally, the method further includes mixing the fresh hydrogen and the hydrogen donor after hydrogen supply and contacting with the regeneration catalyst for the regeneration treatment of the hydrogen donor; the regeneration catalyst is selected from non-noble metal catalysts and / or noble metal catalysts; the non-noble metals in the non-noble metal catalysts are selected from one or more of nickel, molybdenum, and chromium, and the noble metals in the noble metal catalysts are selected from one or more of platinum, palladium, and rhodium; preferably a Pt noble metal catalyst.

[0020] Through the above technical solution, using a hydrogen donor to replace hydrogen as the reactant in the hydrocracking reaction can reduce coking through the hydrogen-donating hydrocracking unit, improve the light oil yield, and also reduce the reaction system pressure. Furthermore, it can improve the safety of the device and is beneficial to the long-term operation of the device. At the same time, the hydrogen donor after hydrogen supply can be recycled back to the hydrocracking unit after restoring its hydrogen supply performance, which can effectively increase economic benefits.

[0021] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. Description of the Drawings

[0022] The accompanying drawings are used to provide a further understanding of the present disclosure and form a part of the specification. Together with the following detailed description, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the accompanying drawings:

[0023] Figure 1 It is a process flow diagram of an embodiment of the method for combined treatment of light distillate oil by hydrogen supply and hydrocracking of the present invention.

[0024] Explanation of reference numerals in the accompanying drawings

[0025] 1. Hydrocracking unit; 2. Separation unit; 3. Hydrogen supply agent hydrogen separation unit; 10. Light distillate oil; 11. Hydrogen supply agent; 12. Hydrocracking reaction product; 13. Fresh hydrogen; 14. Hydrogen supply agent after hydrogen supply; 15. Excess hydrogen; 16. Hydrogen supply agent with restored hydrogen supply performance; 17. Gas product; 18. Liquid product; 19. Unconverted oil. Detailed description of specific embodiments

[0026] The following provides a detailed description of the specific embodiments of the present disclosure with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not used to limit the present disclosure.

[0027] In the present disclosure, unless otherwise stated, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0028] The present disclosure provides a method for combined treatment of light distillate oil by hydrogen supply and hydrocracking. The method includes: mixing the light distillate oil with a hydrogen supply agent and then entering a hydrocracking unit to contact with a hydrocracking catalyst for hydrocracking reaction to obtain a hydrocracking reaction product; feeding the hydrocracking reaction product into a flash tank to obtain a gas product and a flash tank bottom oil, and performing a first separation on the flash tank bottom oil to obtain a hydrogen supply agent after hydrogen supply, a gas product, a liquid product, and an unconverted oil; mixing the hydrogen supply agent after hydrogen supply with fresh hydrogen and then entering a hydrogen supply agent hydrogenation reactor for hydrogen supply agent regeneration treatment, and then performing a second separation to obtain a hydrogen supply agent with restored hydrogen supply performance and excess hydrogen; mixing the excess hydrogen with the fresh hydrogen and then returning it to the hydrogen supply agent hydrogenation reactor; and returning the unconverted oil to the hydrocracking unit.

[0029] Through the above technical solution, a hydrogen donor is used to replace hydrogen as the reactant in the hydrocracking reaction. The hydrogen donor hydrocracking unit can reduce coking, increase the light oil yield, and also reduce the reaction system pressure. Furthermore, it can improve the safety of the device and is conducive to the long-term operation of the device. At the same time, the hydrogen donor after hydrogen supply can be recycled back to the hydrocracking unit after restoring its hydrogen supply performance, which can effectively increase economic benefits.

[0030] In one embodiment, the light distillate oil is selected from one or more of wax oil, diesel oil, and kerosene. In this embodiment, the light distillate oil is a distillate oil with a boiling point below 350 °C.

[0031] In one embodiment, the hydrogen donor is selected from one or more of cyclohexane, cyclohexene, cyclohexadiene, methylcyclohexane, and decalin, and preferably cyclohexane.

[0032] In the above embodiment, using a hydrogen donor to replace hydrogen in the prior art can reduce the pressure of the hydrocracking reaction, further enhance the safety of the reaction, and at the same time, the hydrocracking reaction effect is not much different from that of the reaction with hydrogen.

[0033] In one embodiment, the hydrocracking catalyst is selected from non-noble metal catalysts and / or noble metal catalysts; the non-noble metals in the non-noble metal catalysts are selected from one or more of nickel, molybdenum, and chromium, and the noble metals in the noble metal catalysts are selected from one or more of platinum, palladium, and rhodium; preferably a Ni-Mo series non-noble metal catalyst. In this embodiment, using a hydrocracking catalyst can enhance the reaction activity of the hydrocracking reaction, and thus can increase the light oil yield.

[0034] In one embodiment, the form of the reactor in the hydrocracking unit is one or more of a fixed-bed reactor, a fluidized-bed reactor, and a moving-bed reactor, and preferably a fixed-bed reactor.

[0035] In one embodiment, the reaction conditions of the hydrocracking reaction are as follows: the reaction temperature is 150 - 450 °C, preferably 420 - 430 °C; the reaction pressure is 5 - 100 bar, preferably 35 - 50 bar; the reaction time is 0.5 - 10 h, preferably 1 - 2 h; the feed ratio of the light distillate oil to the hydrogen donor is 0.5 - 100:1 wt%, preferably 1 - 50 wt%.

[0036] In this embodiment, through the above reaction conditions, the reaction activity of the hydrocracking reaction can be enhanced. In order to further enhance the reaction activity of the hydrocracking reaction, the hydrocracking reaction conditions are further optimized.

[0037] In one embodiment, the method further includes, before the hydrocracking reaction, mixing the light distillate oil and the hydrogen donor and then heating the mixture to 150 - 450°C, preferably 420 - 430°C; and increasing the pressure to 5 - 100 bar, preferably 35 - 50 bar.

[0038] In one embodiment, the temperature in the flash tank is 200 - 420°C, and the pressure in the flash tank is 10 - 20 bar; the first separation is carried out in a distillation column; the fractionation cut-off point between the hydrogen donor after hydrogen supply and the liquid product is 130 - 160°C; the fractionation cut-off point between the liquid product and the unconverted oil is 250 - 320°C.

[0039] In one embodiment, the reaction conditions for the regeneration treatment of the hydrogen donor include: the reaction temperature is 150 - 300°C, preferably 180 - 250°C; the reaction pressure is 5 - 70 bar, preferably 20 - 35 bar; the mass ratio of the fresh hydrogen to the hydrogen donor after hydrogen supply is 0.01 - 0.08:1, preferably 0.03 - 0.05:1.

[0040] In this embodiment, the method for regenerating the hydrogen donor is a conventional method in the art. For example, the hydrogen donor after hydrogen supply and hydrogen are sent into a hydrogen donor hydro-separation unit to contact with a regeneration catalyst for the regeneration treatment of the hydrogen donor, so as to obtain a hydrogen donor with restored hydrogen supply performance; and the hydrogen donor with restored hydrogen supply performance is returned to the hydrocracking unit to participate in the reaction.

[0041] In one embodiment, the flow rate ratio of the regenerated hydrogen donor returned to the slurry bed reactor to the fresh hydrogen donor is 0.1 - 99:1.

[0042] In one embodiment, the method further includes mixing the fresh hydrogen with the hydrogen donor after hydrogen supply and then contacting the mixture with a regeneration catalyst for the regeneration treatment of the hydrogen donor; the regeneration catalyst is selected from non-noble metal catalysts and / or noble metal catalysts; the non-noble metals in the non-noble metal catalysts are selected from one or more of nickel, molybdenum, and chromium, and the noble metals in the noble metal catalysts are selected from one or more of platinum, palladium, and rhodium; preferably a Pt noble metal catalyst.

[0043] In one embodiment, as Figure 1 shown, the method for treating light distillate oil includes:

[0044] After mixing the light distillate oil 10 with the hydrogen donor 11, the pressure is increased and the temperature is raised to 5 - 100 barg and 150 - 450 °C, and then it enters the hydrocracking unit 1 for hydrocracking reaction to obtain the hydrocracking reaction product 12; the hydrocracking reaction product 12 is sent to the separation unit 2 and fed into a flash tank for flashing to obtain the gas product 17 and the bottom oil of the flash tank; the bottom oil of the flash tank is sent to the fractionating tower in the separation unit 2 and separated according to different boiling points to obtain the hydrogen donor 14 after hydrogen supply, the liquid product 18 and the unconverted oil 19; the fresh hydrogen 13 is mixed with the hydrogen donor 14 after hydrogen supply and then enters the hydrogen donor hydro-separation unit 3, the temperature is raised and the pressure is increased to 150 - 350 °C, 5 - 60 bar, and a mixture of excess hydrogen 15 and the hydrogen donor 16 with restored hydrogen supply performance is obtained, cooled to below 50 - 120 °C and the excess hydrogen 15 is separated through a flash tank, the excess hydrogen 15 is mixed with the fresh hydrogen 13, and the hydrogen donor 16 with restored hydrogen supply performance is mixed with the hydrogen donor 11 for recycling; the unconverted oil 19 is returned to the hydrocracking unit.

[0045] Regarding the device in the above embodiments, the specific ways in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0046] Except as otherwise specified, all reagents used below are chemically pure reagents. Among them, the hydrocracking catalyst used in the examples is the Ni / Mo@Al2O3 catalyst.

[0047] Example 1

[0048] After mixing light distillate oil 10 (light wax oil, 100 t / h) with hydrogen donor 11 (cyclohexane, with a one-time addition of 100 t and a stabilized flow rate of 10 t / h), the pressure is increased and the temperature is raised to 40 barg and 425 °C, and then it enters the hydrocracking unit 1 to contact with the Ni / Mo@Al2O3 catalyst for hydrocracking reaction, obtaining the hydrocracking reaction product 12; the hydrocracking reaction product 12 is sent into a flash tank for flashing to obtain gas product 17 and the bottom oil of the flash tank; the bottom oil of the flash tank is sent into the fractionating tower in the separation unit 2 and separated according to different boiling points to obtain gas product 17 (boiling range < 80 °C), hydrogen donor 14 after hydrogen supply (boiling range 80 - 140 °C), liquid product 18 (boiling range 140 - 320 °C) and unconverted oil 19 (boiling range > 320 °C); fresh hydrogen 13 and hydrogen donor 14 after hydrogen supply are mixed according to a molar ratio of fresh hydrogen to hydrogen donor after hydrogen supply of 4:1 and then enter the hydrogen donor hydro-separation unit 3, the temperature is raised and the pressure is increased to 200 °C and 30 bar, and a mixture of excess hydrogen 15 and hydrogen donor 16 with restored hydrogen supply performance is obtained, cooled to below 80 °C and the excess hydrogen 15 is separated through a flash tank, the excess hydrogen 15 is mixed with fresh hydrogen 13, and hydrogen donor 16 with restored hydrogen supply performance is mixed with hydrogen donor 11 for recycling, and the total stabilized flow rate is 100 t / h; the unconverted oil 19 is returned to the hydrocracking unit. The product properties are shown in Table 1.

[0049] Comparative Example 1

[0050] A method for hydrocracking treatment of oil products with low hydrogen supply pressure using a traditional hydroprocessing process, wherein the traditional process includes:

[0051] Feeding light distillate oil and hydrogen into a hydrocracking reaction device to contact with a hydrocracking catalyst for hydrocracking reaction; the temperature of the hydrogenation reaction is 360 - 380 °C, the pressure is 16 MPa, the hydrogen partial pressure is 12 - 14 MPa, and the catalyst-oil ratio is 200 ppm. The comparison of product properties with those of Example 1 is shown in Table 1.

[0052] Table 1 Product Properties

[0053]

[0054]

[0055] As can be seen from the data in the table, using the method of the present disclosure can increase the liquid product volume and light oil yield while reducing the coking amount.

[0056] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0057] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination manners.

[0058] Furthermore, any combinations can be made among the various different embodiments of the present disclosure, as long as they do not violate the idea of the present disclosure, and they should equally be regarded as the content disclosed by the present disclosure.

Claims

1. A method for combined hydrotreating and hydrocracking of light distillate oil with hydrogen supply, characterized in that, The method includes: Mixing light distillate oil with a hydrogen donor and then feeding the mixture into a hydrocracking unit to contact with a hydrocracking catalyst for a hydrocracking reaction to obtain a hydrocracking reaction product; Feeding the hydrocracking reaction product into a flash drum to obtain a gas product and a bottom oil of the flash drum, and subjecting the bottom oil of the flash drum to a first separation to obtain a hydrogen donor after hydrogen supply, a liquid product and unconverted oil; Mixing the hydrogen donor after hydrogen supply with fresh hydrogen and then feeding the mixture into a hydrogen donor hydrogenation reactor for hydrogen donor regeneration treatment, and then through a second separation to obtain a hydrogen donor with restored hydrogen supply performance and excess hydrogen; mixing the excess hydrogen with the fresh hydrogen and then returning the mixture to the hydrogen donor hydrogenation reactor; Returning the unconverted oil to the hydrocracking unit; The form of the reactor in the hydrocracking unit is a fixed bed reactor; The hydrogen donor is cyclohexane; The hydrocracking catalyst is a Ni-Mo series non-noble metal catalyst; The conditions of the hydrocracking reaction are: the reaction temperature is 420 - 430 °C, the reaction pressure is 35 - 50 bar, and the feed weight ratio of the light distillate oil to the hydrogen donor is 1 - 50:

1.

2. The method according to claim 1, characterized in that, The light distillate oil is selected from one or more of wax oil, diesel oil and kerosene.

3. The method according to claim 1, wherein The method further includes, before carrying out the hydrocracking reaction, first mixing the light distillate oil and the hydrogen donor and then heating to 150 - 450 °C and increasing the pressure to 5 - 100 bar.

4. The method according to claim 3, wherein Before carrying out the hydrocracking reaction, first mixing the light distillate oil and the hydrogen donor and then heating to 420 - 430 °C and increasing the pressure to 35 - 50 bar.

5. The method according to claim 1, wherein The temperature in the flash drum is 200 - 420 °C, and the pressure in the flash drum is 10 - 20 bar; the first separation is carried out in a distillation column; the fractionation cut-off point of the hydrogen donor after hydrogen supply and the liquid product is 130 - 160 °C; the fractionation cut-off point of the liquid product and the unconverted oil is 250 - 320 °C.

6. The method according to claim 1, characterized in that, The reaction conditions for the hydrogen donor regeneration treatment include: the reaction temperature is 150 - 300 °C, the reaction pressure is 5 - 70 bar, and the mass ratio of the fresh hydrogen to the hydrogen donor after hydrogen supply is 0.01 - 0.08:

1.

7. The method according to claim 6, wherein The reaction conditions for the hydrogen donor regeneration treatment include: the reaction temperature is 180 - 250 °C, the reaction pressure is 20 - 35 bar, and the mass ratio of the fresh hydrogen to the hydrogen donor after hydrogen supply is 0.03 - 0.05:

1.

8. The method according to claim 1, characterized in that, The method further includes mixing the fresh hydrogen with the hydrogen donor after hydrogen supply and then contacting with a regeneration catalyst for the hydrogen donor regeneration treatment; The regeneration catalyst is selected from non-noble metal series catalysts and / or noble metal series catalysts; the non-noble metals in the non-noble metal series catalysts are selected from one or more of nickel, molybdenum and chromium, and the noble metals in the noble metal series catalysts are selected from one or more of platinum, palladium, rhodium and gold.

9. The method according to claim 8, wherein The noble metal series catalyst is a Pt noble metal catalyst.

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