A method and system for hydrocracking high-nitrogen raw materials

Abstract

The present invention provides a method and system for hydrocracking of high-nitrogen raw materials. The hydrocracking system includes a hydrogenation reaction unit, a separation unit, and a second fractionation tower; wherein the hydrogenation reaction unit includes a hydrofining reaction zone and a hydrocracking reaction zone; and the separation unit includes a gas-liquid separator and a first fractionation tower. The method for hydrocracking of high-nitrogen raw materials includes the following steps: high-nitrogen raw oil and hydrogen are mixed and sequentially enter the hydrofining reaction zone and the hydrocracking reaction zone for reaction, and the hydrocracking product oil obtained after the reaction is separated to obtain gas, light naphtha, heavy naphtha, jet fuel, diesel, and tail oil. The method of the present invention not only improves the yield of intermediate distillate oil but also solves the problem of substandard quality of the jet fuel fraction generated by processing high-nitrogen raw materials, providing favorable technical support for the stable and efficient production of enterprises.

Description

Technical Field

[0001] The present invention belongs to the technical field of petrochemical industry, and relates to a hydrocracking method and system, in particular to a single-stage full-cycle hydrocracking method and system for processing high-nitrogen raw materials for hydrocracking to produce more middle distillate oil. Background Art

[0002] With the structural adjustment of energy demand and product market, reducing diesel-to-gasoline ratio and reducing oil consumption and increasing chemical production are the current mainstream development trends. However, the current market demand for fuel products is still diversified, especially for diesel products, which have specific market demand, large transportation demand, diesel demand in northern my country and even in cold regions such as Europe. Generally speaking, the production process of increasing the production of intermediate distillate oil using wax oil as raw material still has a broad application market.

[0003] CN109988629A discloses a wax oil hydrocracking method, which is characterized in that the hydrorefined oil is separated into two parts after contact with a first hydrocracking catalyst, the product obtained by passing one part through a second hydrocracking catalyst is fractionated, and the hydrocracking tail oil obtained by the fractionation is mixed with the first hydrocracking stream and contacted with a hydroisomerization catalyst to obtain naphtha products, aviation kerosene products, etc. of different specifications.

[0004] CN109988629A discloses a two-stage hydrocracking method. This patent involves processing low-quality crude oil and hydrogen for a hydrorefining reaction, obtaining a hydrorefining effluent that undergoes gas-liquid separation. The liquid product enters an enhanced cracking reaction zone. The hydrocracking reaction zone contains two hydrocracking catalysts with different molecular sieve contents. The two catalysts work synergistically to significantly improve the quality of the hydrocracking products, particularly raising the smoke point of the jet fuel fraction.

[0005] CN111763533A discloses a method for processing heavy distillate oil. The ratio of the hydrogenation activity to the cracking activity of the hydrocracking catalyst in the hydrocracking reaction zone shows an increasing trend. This method can increase the yield of the jet fuel fraction while maintaining or even improving the quality of the jet fuel fraction. However, there is no significant improvement in the iodine value properties of the jet fuel. Summary of the Invention

[0006] During the research on the hydrocracking process, the applicant discovered that the full-cycle hydrocracking process for processing high-nitrogen feedstocks to produce the maximum amount of middle distillates using existing process methods has difficult-to-overcome technical bottlenecks, which are mainly reflected in the following aspects: on the one hand, the nitrogen content of the high-nitrogen feedstock is high (usually greater than 2500ppm) and the overall processing is difficult. To ensure the depth of conversion, it is necessary to operate at a relatively high reaction temperature. Operating at such a high temperature will cause the acidic sites of the carrier in the supplementary hydrorefining catalyst (mainly used for olefin hydrogenation and saturation) at the tail of the hydrocracking reactor to play a cracking role, and some saturated hydrocarbons will undergo cracking reactions to produce unsaturated hydrocarbons. The supplementary hydrorefining catalyst cannot fully achieve the saturation effect on the olefins in the feed, which in turn causes the iodine value of the jet fuel product to exceed the standard and fail to meet the use requirements. On the other hand, the operation of the hydrocracking unit at a relatively high reaction temperature, especially the operation of the last catalyst bed at a high reaction temperature, will cause more components to be excessively cracked to produce naphtha fractions, thereby reducing the yield of middle distillates.

[0007] In response to the aforementioned issues, the present invention primarily aims to provide a method and system for hydrocracking high-nitrogen feedstocks. This method proposes recycling a heavy naphtha fraction composed of a specific fraction back to the hydrocracking reactor via a specific location. This reduces the reaction temperature of the tail catalyst bed, and because the heavy naphtha fraction contains a relatively high amount of aromatic components, it competes with the aviation kerosene fraction for adsorption on the acidic sites of the supplemental hydrorefining catalyst, significantly reducing the unsaturated components in the aviation kerosene product fraction. Furthermore, the dynamic inhibition present during the reaction reduces the tendency of the aviation kerosene fraction to split into heavy naphtha components. This method not only increases the yield of intermediate distillate oil but also addresses the issue of excessively high iodine values ​​in the aviation kerosene fraction generated by processing high-nitrogen feedstocks, providing advantageous technical support for stable and efficient production in enterprises.

[0008] In order to achieve the above-mentioned object of the invention, the first aspect of the present invention provides a method for hydrocracking of a high-nitrogen feedstock, comprising the following steps:

[0009] (1) The high nitrogen feedstock oil and hydrogen are mixed and sequentially enter the hydrorefining reaction zone and the hydrocracking reaction zone for reaction to obtain hydrocracking product oil;

[0010] (2) Separating the hydrocracking product oil obtained in step (1) to obtain gas, light naphtha, heavy naphtha, jet fuel, diesel, and tail oil;

[0011] (3) The heavy naphtha obtained in step (2) is fractionated to obtain a light heavy naphtha fraction, a heavy naphtha product, and a heavy heavy naphtha fraction, wherein the light heavy naphtha fraction and the heavy heavy naphtha fraction are recycled back to the middle and lower parts of the hydrocracking reaction zone.

[0012] Preferably, in the above-mentioned hydrocracking method of high-nitrogen feedstock, the tail oil obtained in step (2) is recycled back to the hydrorefining reaction zone.

[0013] Preferably, in the above-mentioned hydrocracking method of high-nitrogen feedstock, the distillation range of the high-nitrogen feedstock is generally 350°C to 570°C, the nitrogen content is greater than 2500ppm, and there is usually no special restriction on the sulfur content. Under normal circumstances, the sulfur content is not more than 3.0wt%. More specifically, the high-nitrogen feedstock can be selected from one or a mixture of straight-run wax oil, ebullated-bed wax oil, coker wax oil, etc.

[0014] Preferably, in the above-mentioned hydrocracking method for high-nitrogen feedstock, the hydrofining reaction zone is provided with more than one hydrofining reactor; and the hydrocracking reaction zone is provided with more than one hydrocracking reactor.

[0015] Preferably, in the above-mentioned high-nitrogen feedstock hydrocracking method, the hydrorefining reaction zone in step (1) is provided with at least one hydrorefining catalyst bed, preferably 1 to 3 hydrorefining catalyst beds; each hydrorefining catalyst bed can be loaded with the same and / or different hydrorefining catalysts. Generally, the hydrorefining catalyst comprises a carrier and a hydrogenation-active metal component, the hydrogenation-active metal component being supported on the carrier, and the hydrogenation-active metal can be at least one selected from Group VIB, Group VIIB, and Group VIII metal elements, preferably two or more metals selected from Co, Mo, Ni, and W as active components. Specifically, commercial hydrorefining catalysts such as FF-12, FF-56, FF-66, and FHUDS-8 developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. can be selected, and can also be prepared according to common knowledge in the art as needed.

[0016] Preferably, in the above-mentioned hydrocracking method for high-nitrogen feedstock, the hydrocracking reaction zone in step (1) is provided with at least two hydrocracking catalyst beds, preferably 2 to 3 hydrocracking catalyst beds; in terms of the material flow direction, the lowermost hydrocracking catalyst bed comprises a hydrocracking catalyst and a supplementary hydrorefining catalyst, and in terms of the material flow direction, the hydrocracking catalyst is above the supplementary hydrorefining catalyst; each hydrocracking catalyst bed can be loaded with the same and / or different hydrocracking catalysts.

[0017] Preferably, in the above-mentioned high-nitrogen feedstock hydrocracking method, the hydrocracking catalyst comprises a hydrogenation metal component and a support. The hydrogenation metal component can generally be selected from at least one of Group VIB, Group VIIB, and Group VIII metal elements, preferably two or more of Co, Mo, Ni, and W; and the support is selected from at least one of Y molecular sieve, β molecular sieve, modified Y molecular sieve, modified β molecular sieve, alumina, and amorphous silica-alumina. Typically, the hydrogenation metal component is present in an oxide content of 18 wt% to 40 wt% based on the weight of the catalyst. Specifically, commercial hydrocracking catalysts such as FC-50 and FC-60 developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. can be selected, or can be prepared according to common knowledge in the art as needed.

[0018] Preferably, in the above-mentioned high-nitrogen feedstock hydrocracking method, the supplemental hydrorefining catalyst comprises a support and a hydrogenation-active metal component, wherein the hydrogenation-active metal component is supported on the support. The hydrogenation-active metal can be at least one metal selected from Group VIB, Group VIIB, and Group VIII, preferably two or more metals selected from Co, Mo, Ni, and W as the active component. Specifically, commercial hydrorefining catalysts such as FF-12, FF-66, and FHUDS-8 developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. can be used, and can also be prepared according to common knowledge in the art as needed.

[0019] Preferably, in the above-mentioned hydrocracking method for high-nitrogen feedstock, the separation in step (2) includes two processes: gas-liquid separation and fractionation. The hydrocracking product oil obtained in step (1) is first subjected to gas-liquid separation to obtain a gas phase stream and a liquid phase stream after separation. The obtained gas phase stream is further purified and compressed by a circulating hydrogen compressor to obtain hydrogen, which can be circulated back to the hydrorefining reaction zone and / or the hydrocracking reaction zone for use. Generally, the purification treatment refers to removing sulfur-containing compounds (such as hydrogen sulfide) in the gas phase stream. The purification treatment can adopt any of the existing processes for removing hydrogen sulfide.

[0020] Preferably, in the above-mentioned hydrocracking method of high-nitrogen feedstock, the distillation range of the light and heavy naphtha fraction in step (3) is 55-100°C, preferably 65-72°C.

[0021] Preferably, in the above-mentioned hydrocracking method of high-nitrogen feedstock, the distillation range of the heavy naphtha fraction in step (3) is 150-190°C, preferably 160-172°C.

[0022] Preferably, in the above-mentioned hydrocracking method of high-nitrogen feedstock, the heavy naphtha fraction enters the hydrocracking reaction zone through a feed port between any two adjacent hydrocracking catalyst beds in the hydrocracking reaction zone, preferably enters the hydrocracking reaction zone through a feed port between two adjacent hydrocracking catalyst beds at the rear end of the liquid phase material flow direction.

[0023] Preferably, in the above-mentioned hydrocracking method for high-nitrogen feedstock, the light and heavy naphtha fraction enters the hydrocracking reaction zone through a feed port between any two adjacent hydrocracking catalyst beds in the hydrocracking reaction zone, preferably enters the hydrocracking reaction zone through a feed port between two adjacent hydrocracking catalyst beds at the rear end of the liquid phase material flow direction.

[0024] Preferably, in the above-mentioned hydrocracking method of high-nitrogen feedstock, the light heavy naphtha fraction and the heavy heavy naphtha fraction are mixed and then enter the hydrocracking reaction zone through a feed port between any two adjacent hydrocracking catalyst beds in the hydrocracking reaction zone, preferably through a feed port between two adjacent hydrocracking catalyst beds at the rear end of the liquid phase material flow direction.

[0025] Preferably, in the above-mentioned high nitrogen feedstock hydrocracking method, the process conditions of the hydrotreating reaction zone in step (1) are generally as follows: reaction temperature is 320-430°C, preferably 370-420°C; reaction pressure is 8.0-18.0 MPa, preferably 12.0-17.0 MPa; volume space velocity is 0.5-10.0 h -1 , preferably 0.8 to 2.0 h -1 ; The volume ratio of hydrogen to oil is 100 to 2500, preferably 600 to 1500.

[0026] Preferably, in the hydrocracking method of the high nitrogen feedstock, the process conditions of the hydrocracking reaction zone in step (1) are generally as follows: reaction temperature is 330-435°C, preferably 370-425°C; reaction pressure is 8.0-18.0 MPa, preferably 12.0-17.0 MPa; volume space velocity is 0.5-8.0 h -1 , preferably 0.6~2.0h -1 ; The hydrogen-to-oil volume ratio is 100-2500, preferably 600-1800.

[0027] A second aspect of the present invention provides a high-nitrogen feedstock hydrocracking system, the hydrocracking system comprising:

[0028] The hydrogenation reaction unit includes a hydrorefining reaction zone and a hydrocracking reaction zone, which is used to receive high-nitrogen feedstock and hydrogen and obtain hydrocracking product oil after reaction;

[0029] The separation unit includes a gas-liquid separator and a first fractionating tower, which is used to receive and separate the hydrocracking oil to obtain gas, light naphtha, heavy naphtha, jet fuel, diesel and tail oil after separation;

[0030] The second fractionating tower is used to receive and separate the heavy naphtha, and obtain a light heavy naphtha fraction, a heavy naphtha product, and a heavy heavy naphtha fraction after fractionation.

[0031] Preferably, in the hydrocracking system of the high-nitrogen feedstock, the tail oil is circulated back to the hydrorefining reaction zone through a pipeline for cyclic treatment.

[0032] Preferably, in the hydrocracking system for the high-nitrogen feedstock, the hydrofining reaction zone is provided with at least one hydrofining reactor; and the hydrocracking reaction zone is provided with at least one hydrocracking reactor.

[0033] Preferably, in the hydrocracking system of the high-nitrogen feedstock, the hydrorefining reaction zone in step (1) is provided with at least one hydrorefining catalyst bed, preferably 1 to 3 hydrorefining catalyst beds; each hydrorefining catalyst bed can be loaded with the same and / or different hydrorefining catalysts.

[0034] Preferably, in the hydrocracking system for the high-nitrogen feedstock, the hydrocracking reaction zone in step (1) is provided with at least two hydrocracking catalyst beds, preferably 2 to 3 hydrocracking catalyst beds; in terms of the material flow direction, the lowermost hydrocracking catalyst bed comprises a hydrocracking catalyst and a supplementary hydrorefining catalyst, and in terms of the liquid-phase material flow direction, the hydrocracking catalyst is above the supplementary hydrorefining catalyst; each hydrocracking catalyst bed may be loaded with the same and / or different hydrocracking catalysts.

[0035] Preferably, in the hydrocracking system for the high-nitrogen feedstock, the light and heavy naphtha fractions enter the hydrocracking reaction zone through a feed port between any two adjacent hydrocracking catalyst beds in the hydrocracking reaction zone.

[0036] Preferably, in the above-mentioned hydrocracking system for high-nitrogen feedstock, the heavy naphtha fraction enters the hydrocracking reaction zone through a feed port between any two adjacent hydrocracking catalyst beds in the hydrocracking reaction zone, preferably enters the hydrocracking reaction zone through a feed port between the two adjacent hydrocracking catalyst beds at the rear end in the direction of liquid phase material flow.

[0037] Preferably, in the above-mentioned hydrocracking method of high-nitrogen feedstock, the light heavy naphtha fraction and the heavy heavy naphtha fraction are mixed and then enter the hydrocracking reaction zone through a feed port between any two adjacent hydrocracking catalyst beds in the hydrocracking reaction zone, preferably through a feed port between two adjacent hydrocracking catalyst beds at the rear end of the liquid phase material flow direction.

[0038] Compared with the existing hydrocracking process for the largest production of middle distillates, the technical advantages and effects of the hydrocracking method and system for high-nitrogen feedstocks provided by the present invention are mainly reflected in the following aspects:

[0039] (1) In the hydrocracking method of high-nitrogen raw materials provided by the present invention, heavy naphtha is fractionated to obtain a light heavy naphtha fraction, a heavy naphtha product, and a heavy heavy naphtha fraction, and the light heavy naphtha fraction and the heavy heavy naphtha fraction are further circulated to the middle and lower part of the hydrocracking reactor. On the one hand, the circulation of these fractions back to the hydrocracking reactor can adjust the catalyst bed temperature in the middle and lower part of the reactor, and the acidic activity of the supplementary hydrorefining catalyst is suppressed, thereby reducing the generation of unsaturated components; on the other hand, the light heavy naphtha fraction and the heavy heavy naphtha fraction have high aromatic hydrocarbon content and short-chain paraffin content, and form a competitive relationship with the aviation kerosene fraction in the catalyst bed at the bottom, which can reduce the generation of unsaturated hydrocarbons in the aviation kerosene fraction, thereby ensuring that the iodine value of the aviation kerosene product is qualified.

[0040] (2) During the research process, the applicant discovered that the hydrocracking reaction has a dynamic inhibition and guidance phenomenon in the cracking reaction zone, that is, in the hydrocracking process of the full-fraction reactants, the introduction of substances with a distillation range of A to B ° C will promote the reaction of substances with a distillation range of less than B ° C, while inhibiting the reaction of substances with a distillation range of more than B ° C. The light heavy naphtha fraction and the heavy heavy naphtha fraction are circulated to the bottom of the hydrocracking reactor to create a high-heavy naphtha atmosphere area, inhibiting the conversion of the jet fuel fraction to the heavy naphtha fraction, thereby increasing the yield of the intermediate distillate oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the hydrocracking method of high-nitrogen feedstock in an embodiment of the present invention.

[0042] Figure 2 Schematic diagram of the hydrocracking method of high nitrogen feedstock in a comparative example of the present invention. DETAILED DESCRIPTION

[0043] The technical solutions and technical effects of the present invention are further described below with reference to the accompanying drawings and specific implementations.

[0044] Unless expressly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising” will be understood to include the stated elements or components but not to exclude other elements or components.

[0045] In this document, for ease of description, spatially relative terms such as "below," "beneath," "down," "above," "above," etc. may be used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that the spatially relative terms are intended to encompass different orientations of an object in use or operation in addition to the orientation depicted in the drawings. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above directions. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatially relative terms used herein should be interpreted accordingly.

[0046] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit specific positions or relative relationships. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable with each other.

[0047]

[0046] All numerical values ​​for parameters (eg, amounts or conditions) herein are to be understood as being modified in all instances by the term "about," whether or not "about" actually precedes the numerical value.

[0048] The following further describes the embodiment of the hydrocracking method of high nitrogen feedstock provided by the present invention. Figure 1 As shown, the working process of the hydrocracking method of high nitrogen feedstock of the present invention is as follows: under the condition of the presence of new hydrogen 17, the feedstock 1 is mixed with the circulating hydrogen 16 and then enters the hydrogenation reaction unit, first enters the hydrofining reactor 2 for reaction, the refined product 3 obtained after the reaction enters the hydrocracking reactor 4 for reaction, and the hydrocracking product oil obtained after the reaction enters the separation unit, which includes a gas-liquid separator 5 and a first fractionating tower 7. After separation by the gas-liquid separator 5, a gas phase stream 14 and a liquid phase stream 6 are obtained, wherein the gas phase stream 14 is purified and then subjected to the first fractionating tower 7. After the circulating hydrogen compressor 15 is activated, it is circulated as circulating hydrogen 16. The liquid stream 6 enters the first distillation tower 7 for separation to obtain gas 8, light naphtha 9, heavy naphtha 10, jet fuel 11, diesel 12 and tail oil 13. The tail oil 13 can be circulated to the hydrotreating reactor for treatment. The heavy naphtha 10 enters the second distillation tower 22 for separation to obtain a light-heavy naphtha fraction 18, a heavy naphtha product 19, and a heavy-heavy naphtha fraction 20. The light-heavy naphtha fraction 18 and the heavy-heavy naphtha fraction 19 are circulated to the middle and lower part of the hydrocracking reactor 4.

[0049] The properties of the raw oils used in the examples of the present invention and the comparative examples are shown in Table 1.

[0050] Table 1 Properties of crude oil

[0051] project wax oil <![CDATA[Density (20 °C), kg / m 3 > 934.2 Nitrogen content, mg / kg 2889 Sulfur content, mg / kg 22800 Distillation range, ℃ 325～556 Freezing point, ℃ 27 Aromatic content, wt% 49.6

[0052] Example 1

[0053] use Figure 1 The hydrocracking method shown in the figure uses feedstock properties as shown in Table 1. The hydrotreating reactor is loaded with FF-66 catalyst, and the hydrocracking reactor has three catalyst beds: the first, second, and third catalyst beds, respectively, in the direction of liquid flow. The hydrocracking catalyst is FC-50, and the final catalyst bed includes both a hydrocracking catalyst and a supplemental hydrotreating catalyst: the FC-50 catalyst and the FF-12 catalyst. The light-heavy naphtha fraction and the heavy-heavy naphtha fraction are recycled to the lower feed port of the hydrocracking reactor, located between the second and third catalyst beds. The distillation range of the light-heavy naphtha fraction is 66-72°C. The distillation range of the heavy-heavy naphtha fraction is 165-170°C. The reaction conditions of the hydrotreating reactor are as follows: reaction pressure of 16.0 MPa, reaction temperature of 390 °C, volume space velocity of 1.0 h -1 The hydrogen-to-oil volume ratio is 1200. The reaction conditions of the hydrocracking reactor are as follows: the reaction pressure is 16.0 MPa, the volume space velocity of the hydrocracking catalyst is 1.2 h -1 , the volume space velocity of the supplementary hydrorefining catalyst is 20h -1 The hydrogen-to-oil volume ratio was 1500, and the temperature of the hydrocracking reactor was adjusted to control the conversion rate to 98%. The reaction results are shown in Table 2.

[0054] Example 2

[0055] use Figure 1The hydrocracking method shown in the figure uses feedstock properties as shown in Table 1. The hydrotreating reactor is loaded with FF-66 and FF-76 catalysts in a graded, top-down configuration, with a volume ratio of 1:2. The hydrocracking reactor is equipped with four catalyst beds: the first, second, third, and fourth beds, respectively, in the direction of liquid flow. The hydrocracking catalyst is FC-14. The final catalyst bed contains both a hydrocracking catalyst and a supplemental hydrotreating catalyst: FC-14 and FF-66, respectively. The light-heavy naphtha fraction is mixed with the heavy-heavy naphtha fraction and then recycled to the hydrocracking reactor through a feed port located in the lower middle section of the reactor, between the third and fourth catalyst beds. The distillation range of the light-heavy naphtha fraction is 65-70°C. The distillation range of the heavy naphtha fraction is 160-168°C. The reaction conditions of the hydrotreating reactor are as follows: reaction pressure of 12.0 MPa, reaction temperature of 399°C, volume space velocity of 0.6 h -1 , the hydrogen-oil volume ratio is 1500. The reaction conditions of the hydrocracking reactor are as follows: the reaction pressure is 12.0 MPa, the volume space velocity of the hydrocracking catalyst is 0.8 h -1 , the volume space velocity of the supplementary hydrofining catalyst is 18h -1 The hydrogen-to-oil volume ratio was 1600, and the temperature of the hydrocracking reactor was adjusted to control the conversion rate to 98%. The reaction results are shown in Table 2.

[0056] Example 3

[0057] use Figure 1The hydrocracking method shown in the figure uses feedstock properties as shown in Table 1. The hydrotreating reactor is loaded with FF-66 catalyst; the hydrocracking reactor is equipped with three catalyst beds: the first, second, and third catalyst beds, respectively, in the direction of liquid flow. The hydrocracking catalyst is FC-60, and the final catalyst bed includes a hydrocracking catalyst and a supplemental hydrotreating catalyst, the latter being FC-60 and FF-56. The light-heavy naphtha fraction is circulated back to the hydrocracking reactor through the lower feed port (located between the second and third catalyst beds within the hydrocracking reactor), while the heavy-heavy naphtha fraction is circulated back to the hydrocracking reactor through the middle feed port (located between the first and second catalyst beds within the hydrocracking reactor). The distillation range of the light heavy naphtha fraction is 65-72°C, and the distillation range of the heavy heavy naphtha fraction is 160-172°C. The reaction conditions of the hydrotreating reactor are as follows: reaction pressure of 17.0 MPa, reaction temperature of 392°C, volume space velocity of 0.8 h -1 The hydrogen-to-oil volume ratio is 1100. The reaction conditions of the hydrocracking reactor are as follows: the reaction pressure is 17.0 MPa, the volume space velocity of the hydrocracking catalyst is 0.6 h -1 , the volume space velocity of the supplementary hydrofining catalyst is 16h -1 The hydrogen-to-oil volume ratio was 1200, and the temperature of the hydrocracking reactor was adjusted to control the conversion rate to 95%. The reaction results are shown in Table 2.

[0058] like Figure 2 As shown, the working process of the hydrocracking method provided in the comparative example of the present invention is as follows: in the presence of new hydrogen 17, the raw oil 1 is mixed with the circulating hydrogen 16 and then enters the hydrogenation reaction unit, first entering the hydrofining reactor 2 for reaction, and the refined product 3 obtained after the reaction enters the hydrocracking reactor 4 for reaction, and the hydrocracking product oil obtained after the reaction enters the separation unit, the separation unit includes a gas-liquid separator 5 and a first distillation tower 7, and after separation by the gas-liquid separator 5, a gas phase stream 14 and a liquid phase stream 6 are obtained, wherein the gas phase stream 14 is purified and then recycled as the circulating hydrogen 16 after the action of the circulating hydrogen compressor 15, and the liquid phase stream 6 enters the first distillation tower 7 for separation to obtain gas 8, light naphtha 9, heavy naphtha 10, jet fuel 11, diesel 12 and tail oil 13, and the tail oil 13 can be recycled to the hydrofining reactor for treatment.

[0059] Comparative Example 1

[0060] use Figure 2The hydrocracking method shown in Table 1 uses feedstock properties. The hydrotreating reactor is loaded with FF-66 catalyst, the hydrocracking reactor is loaded with FC-50 catalyst, and the supplemental hydrotreating catalyst is FF-12 catalyst. The reaction conditions in the hydrotreating reactor are as follows: reaction pressure of 16.0 MPa, reaction temperature of 390°C, and volume space velocity of 1.0 h -1 The hydrogen-to-oil volume ratio is 1200. The reaction conditions of the hydrocracking reactor are as follows: the reaction pressure is 16.0 MPa, the volume space velocity of the hydrocracking catalyst is 1.2 h -1 , the volume space velocity of the supplementary hydrorefining catalyst is 20h -1 The hydrogen-to-oil volume ratio was 1500, and the temperature of the hydrocracking reactor was adjusted to control the conversion rate to 98%. The reaction results are shown in Table 2.

[0061] Comparative Example 2

[0062] use Figure 2 The hydrocracking method shown in Table 1 uses feedstock properties processed. The hydrotreating reactor is loaded with FF-66 and FF-76 catalysts in a graded, top-down configuration, with a volume ratio of 1:2. The hydrocracking reactor is loaded with FC-14 catalyst, supplemented with FF-66 catalyst. The hydrotreating reactor has four beds, and the reaction conditions are as follows: a reaction pressure of 12.0 MPa, a reaction temperature of 399°C, and a volume space velocity of 0.6 h / min. -1 , the hydrogen-oil volume ratio is 1500. The reaction conditions of the hydrocracking reactor are as follows: the reaction pressure is 12.0 MPa, the volume space velocity of the hydrocracking catalyst is 0.8 h -1 , the volume space velocity of the supplementary hydrorefining catalyst is 18.0h -1 The hydrogen-to-oil volume ratio was 1600, and the temperature of the hydrocracking reactor was adjusted to control the conversion rate to 98%. The reaction results are shown in Table 2.

[0063] Comparative Example 3

[0064] use Figure 2 The hydrocracking process shown in Table 1 uses the following properties for the processed wax feedstock. The refining reactor is loaded with FF-66 catalyst, the hydrocracking reactor is loaded with FC-60 catalyst, and the hydrorefining supplemental catalyst is FF-56 catalyst. The hydrocracking reactor has three beds. The hydrorefining reactor reaction conditions are as follows: reaction pressure of 17.0 MPa, reaction temperature of 392°C, and volumetric space velocity of 0.8 h / min. -1 The hydrogen-to-oil volume ratio is 1100. The reaction conditions of the hydrocracking reactor are as follows: the reaction pressure is 17.0 MPa, the volume space velocity of the hydrocracking catalyst is 0.6 h -1 The volumetric space velocity of the hydrogenation refining catalyst is 16.0h-1 The hydrogen-to-oil volume ratio was 1200, and the temperature of the hydrocracking reactor was adjusted to control the conversion rate to 95%. The reaction results are shown in Table 2.

[0065] Table 2 Reaction results of Examples and Comparative Examples

[0066]

[0067]

[0068] The experimental results of the above examples and comparative examples demonstrate that the hydrocracking method for treating high-iodine-value jet fuel significantly reduces the iodine value of the jet fuel product while significantly increasing the yield of middle distillate oil and liquid products. This method not only meets the production needs of enterprises but also improves production economic benefits. This method will help refineries improve quality and efficiency, providing refineries with sufficient high-value fuel products.

Claims

1. A method for hydrocracking a high-nitrogen feedstock, comprising the following steps: (1) The high nitrogen feedstock and hydrogen are mixed and sequentially fed into the hydrotreating reaction zone and the hydrocracking reaction zone for reaction, and hydrocracking oil is obtained after the reaction; the distillation range of the high nitrogen feedstock is 350°C to 570°C, and the nitrogen content is greater than 2500ppm; (2) Separating the hydrocracking product oil obtained in step (1) to obtain gas, light naphtha, heavy naphtha, jet fuel, diesel and tail oil; (3) The heavy naphtha obtained in step (2) is fractionated to obtain a light heavy naphtha fraction, a heavy naphtha product, and a heavy heavy naphtha fraction, wherein the light heavy naphtha fraction and the heavy heavy naphtha fraction are recycled to the middle and lower parts of the hydrocracking reaction zone; the distillation range of the light heavy naphtha fraction is 55 to 100° C.; and the distillation range of the heavy heavy naphtha fraction is 150 to 190° C.; The hydrocracking reaction zone is provided with at least two hydrocracking catalyst beds. In the direction of material flow, the lowermost hydrocracking catalyst bed includes a hydrocracking catalyst and a supplemental hydrorefining catalyst. In the direction of material flow, the hydrocracking catalyst is above the supplemental hydrorefining catalyst. The heavy naphtha fraction enters the hydrocracking reaction zone through the feed port between two adjacent hydrocracking catalyst beds at the rear end of the liquid phase material flow direction; The light and heavy naphtha fractions enter the hydrocracking reaction zone through a feed port between two adjacent hydrocracking catalyst beds at the rear end of the liquid phase material flow direction.

2. The hydrocracking method of high nitrogen feedstock according to claim 1, wherein: The tail oil obtained in step (2) is circulated back to the hydrotreating reaction zone.

3. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The high nitrogen raw material is selected from one or more of straight-run wax oil, ebullated bed wax oil and coking wax oil.

4. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The hydrofining reaction zone is provided with more than one hydrofining reactor; the hydrocracking reaction zone is provided with more than one hydrocracking reactor.

5. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The hydrorefining reaction zone in step (1) is provided with at least one hydrorefining catalyst bed, and each hydrorefining catalyst bed is loaded with the same and / or different hydrorefining catalysts.

6. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The hydrotreating reaction zone in step (1) is provided with 1 to 3 hydrotreating catalyst beds.

7. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The hydrocracking reaction zone in step (1) is provided with 2 to 3 hydrocracking catalyst beds; each hydrocracking catalyst bed is loaded with the same and / or different hydrocracking catalysts.

8. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The separation in step (2) includes two processes: gas-liquid separation and fractionation.

9. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The distillation range of the light and heavy naphtha fractions in step (3) is 65-72°C.

10. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The distillation range of the heavy naphtha fraction in step (3) is 160-172°C.

11. The method for hydrocracking high-nitrogen feedstock according to claim 1, wherein: The light heavy naphtha fraction and the heavy heavy naphtha fraction are mixed and enter the hydrocracking reaction zone through the feed port between two adjacent hydrocracking catalyst beds at the last end of the liquid phase material flow direction.

12. The method for hydrocracking high-nitrogen feedstock according to claim 1, wherein: The process conditions of the hydrofining reaction zone in step (1) are as follows: reaction temperature is 320-430°C; reaction pressure is 8.0-18.0 MPa; volume space velocity is 0.5-10.0 h -1 ; The volume ratio of hydrogen to oil is 100~2500.

13. The hydrocracking method for high nitrogen feedstock according to claim 1, wherein: The process conditions of the hydrofining reaction zone in step (1) are as follows: reaction temperature is 370-420°C; reaction pressure is 12.0-17.0 MPa; volume space velocity is 0.8-2.0 h -1 ; The volume ratio of hydrogen to oil is 600~1500.

14. The hydrocracking method for high-nitrogen feedstock according to claim 1, wherein: The process conditions of the hydrocracking reaction zone in step (1) are as follows: reaction temperature is 330-435°C; reaction pressure is 8.0-18.0 MPa; volume space velocity is 0.5-8.0 h -1 ; The volume ratio of hydrogen to oil is 100~2500.

15. The method for hydrocracking high-nitrogen feedstock according to claim 1, wherein: The process conditions of the hydrocracking reaction zone in step (1) are as follows: reaction temperature of 370-425°C; reaction pressure of 12.0-17.0 MPa; volume space velocity of 0.6-2.0 h -1 ; The volume ratio of hydrogen to oil is 600~1800.

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