Hydrocracking method for producing heavy naphtha

Abstract

The present invention discloses a hydrocracking method for producing heavy naphtha. The method includes a hydrofining reaction zone and a hydrocracking reaction zone, and the process includes: after diesel feedstock, hydrogen and circulating oil are mixed, they pass through the hydrofining reaction zone to carry out hydrofining reaction, control the nitrogen content of the effluent of the hydrofining reaction zone to be below 25 mg / kg, the effluent of the hydrofining reaction zone is mixed with part of liquefied gas and part of light naphtha and then enters the hydrocracking reaction zone for reaction, and the effluent of the hydrocracking reaction zone is separated and fractionated to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel, wherein diesel is circulated back to the hydrofining reaction zone as the circulating oil, and part of the liquefied gas and part of the light naphtha are circulated back to the hydrocracking reaction zone. The method of the present invention can realize the maximum production of heavy naphtha by processing diesel feedstock in a single stage and in a full cycle.

Description

Technical Field

[0001] The present invention relates to a hydrocracking method, in particular to a hydrocracking method for producing heavy naphtha. Background Art

[0002] The fuel demand in the Chinese market is sluggish. Compared with the annual increase in crude oil processing volume, the proportion of diesel products in the refining product structure is decreasing year by year, and it is inevitable to convert part of the diesel raw materials into gasoline fractions and jet fuel fractions. While processing part of the diesel raw materials, hydrocracking also needs to adjust its own product structure to produce chemical raw materials in the largest amount or produce more chemical raw materials and jet fuel products, etc., while reducing diesel, it provides high-quality raw materials for catalytic reforming units and ethylene units to adapt to the rapid growth of demand for basic chemical raw materials such as aromatics and ethylene in the Chinese market.

[0003] There is an overproduction of diesel and a shortage of gasoline, and this trend is more obvious in some parts of China. Refining companies need to adapt to market demand in advance, adjust their product mix, increase production of jet fuel and gasoline, reduce diesel production, and lower the diesel-to-gasoline ratio.

[0004] At present, the overall diesel-to-gasoline ratio of China's oil refining enterprises is relatively high. The straight-run diesel produced by the atmospheric vacuum unit, the coking diesel produced by the delayed coking unit, the catalytic diesel produced by the catalytic cracking unit and a small amount of diesel fractions produced by the hydrocracking unit constitute the main components in the diesel pool.

[0005] Since hydrocracking is an optimizer for product structure adjustment and a powerful tool for reducing diesel-gasoline ratio, it is necessary to conduct catalyst and process research for hydrocracking to produce more chemical raw materials, systematically study the influence of raw material type, hydrocracking catalyst type and naphtha yield on the law of hydrocracking reaction; improve the performance of hydrocracking catalyst and extend the service life; optimize process parameters and reaction conditions to maximize the processing of diesel to produce high-quality reforming unit feed. Among the many influences mentioned above, process conditions have a great influence on increasing the production of heavy naphtha, especially how to optimize process parameters to produce more heavy naphtha when processing straight-run diesel requires in-depth research.

[0006] CN201610958509.6 discloses a hydrocracking method for producing heavy naphtha and tail oil, the method comprising: in the presence of hydrogen, reacting the raw oil through a hydrofining reactor and a hydrocracking reactor in sequence to obtain a hydrocracking effluent; then introducing the hydrocracking effluent into a separation device for gas-liquid separation and fractionation in sequence to obtain a light naphtha fraction, a heavy naphtha fraction, a kerosene fraction, a diesel fraction and a tail oil fraction; introducing at least part of the kerosene fraction and / or at least part of the diesel fraction into the first catalyst bed of the hydrocracking reactor for circulation. This method does not take into account the composition characteristics of the circulating oil, and does not control the multiple cracking of its cracking process, and the heavy oil yield is not high.

[0007] CN201911031585.2 discloses a hydrocracking method for producing heavy naphtha, the method comprising: raw materials and hydrogen are mixed into a hydrocracking pretreatment reaction zone for desulfurization, denitrogenation and aromatic saturation reaction; the reaction effluent enters the first hydrocracking reaction zone for hydrocracking reaction; the hydrogen-rich gas obtained after gas-liquid separation in a separator is used as circulating hydrogen, and the liquid phase enters a fractionation tower for fractionation to obtain gas, light naphtha, heavy naphtha and tail oil fractions; the obtained tail oil is mixed with hydrogen and enters the second hydrocracking reaction zone; the reaction effluent is mixed with the first hydrocracking reaction effluent and then separated by gas-liquid separation, and then enters a fractionation tower for separation to obtain gas, light naphtha, heavy naphtha and tail oil fractions. This method cannot avoid the problem that the circulating oil component is single, excessive cracking is prone to occur, and the yield of heavy naphtha is low.

[0008] In the above methods, either the intermediate distillate oil recycling reaction is used to increase the yield of the target product, or a two-stage reaction system is used to increase the yield of the target product. However, further research is still needed on how to produce heavy naphtha. Summary of the invention

[0009] When heavy naphtha is produced by a conventional single-stage hydrocracking method, it is usually considered to circulate the fraction heavier than heavy naphtha to the hydrocracking reactor for further cracking to increase the production of heavy naphtha, which is generally called a single-stage full-cycle hydrocracking process. The inventors of the present invention have found through extensive research that on the basis of a single-stage full-cycle hydrocracking process, the fraction heavier than heavy naphtha is circulated to the hydrofining reactor, and part of the liquefied gas and light naphtha fraction is circulated back to the hydrocracking reactor and the circulation amount is controlled. The circulated liquefied gas and light naphtha fraction can effectively control the reaction balance of the whole fraction, and can achieve the purpose of increasing the production of heavy naphtha and improving the quality of heavy naphtha, thereby realizing the present invention.

[0010] In view of the problems existing in the prior art, the present invention provides a hydrocracking method for producing heavy naphtha. The present invention can realize the maximum production of heavy naphtha by processing diesel raw materials in a single stage and full cycle.

[0011] The invention provides a hydrocracking method for producing heavy naphtha, which comprises a hydrofining reaction zone and a hydrocracking reaction zone. The process comprises: after diesel feedstock, hydrogen and circulating oil are mixed, they pass through the hydrofining reaction zone to carry out hydrofining reaction, control the nitrogen content of the effluent of the hydrofining reaction zone to be below 25 mg / kg, preferably 1-15 mg / kg, the effluent of the hydrofining reaction zone is mixed with part of liquefied gas and part of light naphtha and then enters the hydrocracking reaction zone for reaction, and the effluent of the hydrocracking reaction zone is separated and fractionated to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel, wherein the diesel is circulated back to the hydrofining reaction zone as the circulating oil, and part of the liquefied gas and part of the light naphtha are circulated back to the hydrocracking reaction zone.

[0012] In the hydrocracking method, the diesel is a fraction heavier than heavy naphtha, generally a fraction with an initial distillation point higher than 175°C.

[0013] In the hydrocracking method, the hydrocracking reaction zone is provided with a plurality of hydrocracking catalyst beds, preferably more than 3, and further preferably 4 to 5. The beds can be divided by a cold hydrogen box.

[0014] In the hydrocracking method, hydrogen is separated at the top of the separation system and can be circulated back to the hydrofining reaction zone and the hydrocracking reaction zone as circulating hydrogen.

[0015] In the hydrocracking method, the hydrorefining reaction zone is filled with a hydrorefining catalyst, which includes a carrier and a hydrogenation active metal; the hydrogenation active metal includes a Group VIB metal and / or a Group VIII metal, and the carrier is an inorganic refractory oxide, which can be selected from one or more of alumina, amorphous silica-alumina, silicon dioxide, titanium oxide, etc. The Group VIB metal is preferably W and / or Mo, and the Group VIII metal is preferably Ni and / or Co. Based on the weight of the catalyst, the content of the Group VIB metal in terms of oxide is 12% to 37%, preferably 15% to 32%, and the content of the Group VIII metal in terms of oxide is 0.5% to 7.5%, preferably 1% to 7%. The hydrorefining catalyst can be various commercial catalysts, or it can be prepared according to the prior art in the art. When the hydroprocessing catalyst is prepared according to the prior art in the art, the catalyst carrier is generally prepared first, and then the active metal component is loaded by impregnation. Commercial hydrotreating catalysts mainly include: 3926, 3936, CH-20, FF-14, FF-18, FF-24, FF-26, FF-36, FF-66, FH-98, FH-UDS, FZC-41 and other hydrotreating catalysts developed by Dalian Petrochemical Research Institute, HR-416, HR-448 and other hydrotreating catalysts of IFP, ICR174, ICR178, ICR 179 and other hydrotreating catalysts of CLG, HC-P, HC-K UF-210 / 220 newly developed by UOP, TK-525, TK-555, TK-557 and other hydrotreating catalysts of Topsoe, KF-752, KF-840, KF-848, KF-901, KF-907 and other hydrotreating catalysts of AKZO.

[0016] In the hydrocracking method, the hydrocracking reaction zone is loaded with a hydrocracking catalyst. The hydrocracking catalyst includes a cracking component, a hydrogenation component and a binder. The cracking component includes amorphous silicon aluminum and / or a molecular sieve, and the molecular sieve includes but is not limited to a Y-type molecular sieve, such as a USY-type molecular sieve. The binder can be aluminum oxide and / or silicon oxide. The hydrogenation component is selected from one or more of the metals, metal oxides or metal sulfides of Group VI, Group VII, and Group VIII, preferably one or more of iron, chromium, molybdenum, tungsten, cobalt, nickel, or their sulfides or oxides. Based on the weight of the catalyst, the content of the hydrogenation component is 12wt% to 42wt% in terms of oxide, preferably 18wt% to 38wt%, and the content of the molecular sieve is 1wt to 30wt%. The hydrocracking catalyst can be selected from an existing commercial hydrocracking catalyst, or a specific hydrocracking catalyst can be prepared as needed. The commercial hydrocracking catalyst can be FC-50, FC-60, etc. developed by Dalian Petrochemical Research Institute.

[0017] In the hydrocracking method, the present invention can process diesel raw materials suitable for hydrocracking technology, and the diesel raw materials can be one or more of straight-run diesel, catalytic diesel, ebullated-bed hydrogenated diesel, coking diesel, etc., preferably containing straight-run diesel raw materials, and further, the straight-run diesel accounts for more than 25wt% of the total mass of the diesel raw materials, preferably 26wt% to 100wt%.

[0018] In the hydrocracking method, the nitrogen content in the straight-run diesel is generally below 0.04wt%, preferably below 0.01wt%, further 0.001wt% to 0.0099wt%, and there is no special requirement for the sulfur content. The initial distillation point is generally 150 to 250°C, the final distillation point is generally 310 to 380°C, and the aromatics content is 5wt% to 35wt%, preferably 10wt% to 30wt%. The straight-run diesel raw material can be selected from various atmospheric diesels (normal second and third lines) obtained by processing suitable crude oil, and can be one or more of various atmospheric diesels (normal second and third lines) obtained by processing Iranian crude oil or Saudi crude oil, such as one or more of Iranian normal second and third lines, Saudi normal second and third lines, etc., or can be one or more of various atmospheric diesels (normal third line) obtained by processing Daqing crude oil or Liaohe crude oil, such as one or more of Daqing normal second and third lines, Liaohe normal second and third lines, etc. Any liquid straight-run diesel oil product suitable as a raw material for a hydrocracking unit is within the applicable scope.

[0019] In the hydrocracking method, in order to further reduce the concentrated cracking of saturated hydrocarbons during the reaction of straight-run diesel feedstock and to achieve the increase in the output of heavy naphtha in the present invention, catalytic diesel can be mixed and refined in the straight-run diesel feedstock, and the catalytic diesel accounts for less than 65wt% of the total mass of the diesel feedstock, preferably 1wt% to 65wt%. The initial boiling point of catalytic diesel is generally 110 to 230°C, preferably 120 to 220°C, the final boiling point is generally 310 to 390°C, preferably 320 to 380°C, the aromatic content is above 65wt%, preferably above 70wt%, and further 71wt% to 90wt%; the density (20°C) of the catalytic diesel feedstock is generally 0.91g·cm -3 Above, preferably 0.92 g·cm -3 Above, further 0.92 g·cm -3 ~0.97g·cm -3 The catalytic diesel raw material can be a catalytic cracking product oil obtained by processing any suitable crude oil, such as a catalytic diesel component using Middle East crude oil as a raw material, specifically, it can be a catalytic diesel obtained by processing Iranian crude oil, Saudi crude oil, etc., or it can be a catalytic diesel component using Chinese crude oil as a raw material, specifically, it can be a catalytic diesel obtained by processing Daqing crude oil, Liaohe crude oil, etc.

[0020] In the hydrocracking method, the main process conditions of the hydrotreating reaction zone are as follows: average reaction temperature 280°C to 400°C, inlet hydrogen to oil volume ratio 200:1 to 900:1, operating pressure 6.0MPa to 10.0MPa, liquid hourly volume space velocity 0.5h -1 ~5.0h -1 Preferably, the average reaction temperature is 300°C to 380°C, the inlet hydrogen-to-oil volume ratio is 300:1 to 800:1, the operating pressure is 6.5MPa to 9.5MPa, and the liquid hourly volume space velocity is 0.8h -1 ~4.5h -1 .

[0021] In the hydrocracking method, the main process conditions of the hydrocracking reaction zone are as follows: average reaction temperature 310°C to 410°C, inlet hydrogen-oil volume ratio 400:1 to 1100:1, operating pressure 6.0MPa to 10.0MPa, liquid hourly volume space velocity 0.5h -1 ~5.0h -1 Preferably, the average reaction temperature is 320°C to 400°C, the inlet hydrogen-oil volume ratio is 500:1 to 1000:1, the operating pressure is 6.5MPa to 9.5MPa, and the liquid hourly volume space velocity is 0.8h -1 ~4.5h -1 .

[0022] In the hydrocracking method, the separation and fractionation processes are all knowledge that technicians in the field should know and are familiar with, and there are no additional requirements, so they will not be described in detail.

[0023] In the hydrocracking method, the main components of the liquefied gas are C3 and C4 components, and the light naphtha is preferably a fraction with a distillation temperature higher than that of the liquefied gas and less than 65°C in the hydrocracking product. After the two are circulated, they can inhibit excessive cracking of the heavy naphtha in the cracking section, thereby increasing the production of the target product, while their own consumption is relatively low.

[0024] In the hydrocracking method, based on the heavy naphtha output, the mass fraction of the circulating amount of liquefied gas to the heavy naphtha output is 7wt% to 10wt%; the mass fraction of the circulating amount of light naphtha to the heavy naphtha output is 13wt% to 17wt%.

[0025] Compared with the prior art, it has the following beneficial effects:

[0026] (1) The hydrocracking method of the present invention uses straight-run diesel as a raw material to perform deep cracking and cyclic operation to produce more heavy naphtha. In this process, by introducing reasonable materials, the dispersion of the components in the reaction process is achieved, the difference in the raw material structure is improved, thereby avoiding the excessive reaction of a single straight-run saturated component and improving the yield of the target product heavy naphtha.

[0027] (2) The diesel component of the hydrocracking method of the present invention is recycled to the refining section, which can minimize the accumulation of polycyclic aromatic hydrocarbons in the whole cycle process under medium and low pressure conditions; the liquefied gas and light naphtha are recycled to the cracking section, which will inhibit the excessive cracking of heavy naphtha. This process fundamentally introduces the full fraction generated by the side reaction, and utilizes the principle of full product suppression to maximize the retention of heavy naphtha, thereby improving the quality of heavy naphtha.

[0028] (3) The hydrocracking method of the present invention can achieve the purpose of maximizing the production of high-quality heavy naphtha. It has the advantages of small investment, great effect, easy operation, etc., which is very consistent with the general direction of the current refining process layout adjustment. It is applicable to both the design of new equipment and the transformation of old equipment. It can reduce the low-demand diesel and increase the high-demand heavy naphtha, and has broad application prospects.

[0029] (4) In the process operation of the present invention, a hydrocracking catalyst with a low molecular sieve content is used according to the characteristics of the reaction raw materials, and multiple hydrocracking catalyst beds are used to reduce the reaction temperature. In addition to extending the operation cycle, the production of the target product can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0031] The method of the present invention is described below in conjunction with the accompanying drawings. Some conventional unit diagrams that are not necessary for description are integrated and summarized as a separation system and a fractionation system.

[0032] like Figure 1 As shown, the process flow of the present invention is as follows:

[0033] The raw oil 1, the circulating oil 14 and the circulating hydrogen 7 are mixed and enter the hydrorefining reaction zone 2 filled with a hydrorefining catalyst for hydrorefining reaction. The reaction effluent 3 enters the hydrocracking reaction zone 4 filled with a multi-bed hydrocracking catalyst for hydrocracking reaction. The reaction effluent 5 enters the separation system 6 for separation. The circulating hydrogen 7 obtained at the top is circulated back to the hydrorefining reaction zone 2. The reaction stream 8 discharged from the bottom enters the subsequent fractionation system 9 for product fractionation. From top to bottom, dry gas 10, liquefied gas 11, light naphtha 12, heavy naphtha 13 and circulating oil (diesel) 14 are obtained in sequence, wherein the liquefied gas 11 and the light naphtha 12 are partially produced and returned to the hydrocracking reaction zone 4 for reaction, and the circulating oil 14 is produced and returned to the hydrorefining reaction zone 2 for reaction. The final product of the present invention is mainly heavy naphtha 13, thereby achieving an increase in the production of heavy naphtha.

[0034] The method of the present invention is further described below with reference to the embodiments and comparative examples.

[0035] In the present invention, unless otherwise specified, percentages refer to mass fractions.

[0036] The process of the method of the present invention is as follows: Figure 1 The properties of the raw oil involved are shown in Table 1, the main physical and chemical properties of the catalyst are shown in Table 2, the relevant control conditions are shown in Table 3, and the effect comparison is shown in Table 4.

[0037] Example 1

[0038] This embodiment is based on the method and Figure 1 The process operation is to process the crude oil 1 in Table 1, the hydrotreating reaction zone is filled with FF-66, the hydrocracking reaction zone is filled with FC-50, and the liquid hourly volume space velocity in the hydrotreating reaction zone is 2.0h -1 The reaction temperature is 348°C, the reaction pressure is 9.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 3mg / kg, and the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction. Four beds are set in the hydrocracking reaction zone. The reaction conditions are liquid hourly volume space velocity of 2.0h -1 , the reaction temperature is 370℃, the reaction pressure is 9.2MPa, the hydrogen-to-oil volume ratio is 800, the single-pass conversion rate is 60%, and the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction is circulated back to the hydrofining reaction zone for further reaction. The liquefied gas and light naphtha are circulated back to the hydrocracking reaction zone for further reaction, wherein the circulating liquefied gas accounts for 8% of the weight of the heavy naphtha, and the circulating light naphtha accounts for 14% of the weight of the heavy naphtha.

[0039] Example 2

[0040] This embodiment is based on the method and Figure 1 The process operation is to process the crude oil 2 in Table 1, the hydrotreating reaction zone is filled with FF-66, the hydrocracking reaction zone is filled with FC-50, and the liquid hourly volume space velocity in the hydrotreating reaction zone is 2.0h -1 The reaction temperature is 340℃, the reaction pressure is 9.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 3mg / kg, the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction, and 4 beds are set in the hydrocracking reaction zone. The reaction conditions are liquid hourly volume space velocity of 2.0h -1, the reaction temperature is 365℃, the reaction pressure is 9.2MPa, the hydrogen-to-oil volume ratio is 800, the single-pass conversion rate is 60%, and the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction is circulated back to the hydrorefining reaction zone for further reaction. The liquefied gas and light naphtha are circulated back to the hydrocracking reaction zone for further reaction, wherein the circulating liquefied gas accounts for 8% of the weight of the heavy naphtha, and the circulating light naphtha accounts for 14% of the weight of the heavy naphtha.

[0041] Example 3

[0042] This embodiment is based on the method and Figure 1 The process operation is to process the feedstock 1 in Table 1, the hydrotreating reaction zone is filled with FF-66, the hydrocracking reaction zone is filled with FC-50, and the liquid hourly volume space velocity in the hydrotreating reaction zone is 2.2h -1 The reaction temperature is 352°C, the reaction pressure is 8.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 3mg / kg, and the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction. Four beds are set in the hydrocracking reaction zone. The reaction conditions are liquid hourly volume space velocity of 2.0h -1 , the reaction temperature is 373℃, the reaction pressure is 8.2MPa, the hydrogen-to-oil volume ratio is 800, the single-pass conversion rate is 60%, and the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction is circulated back to the hydrofining reaction zone for further reaction. The liquefied gas and light naphtha are circulated back to the hydrocracking reaction zone for further reaction, wherein the circulating liquefied gas accounts for 8% of the weight of the heavy naphtha, and the circulating light naphtha accounts for 14% of the weight of the heavy naphtha.

[0043] Example 4

[0044] This embodiment is based on the method and Figure 1 The process operation is to process the crude oil 1 in Table 1, the hydrotreating reaction zone is filled with FF-66, the hydrocracking reaction zone is filled with FC-50, and the liquid hourly volume space velocity in the hydrotreating reaction zone is 2.0h -1 The reaction temperature is 353°C, the reaction pressure is 9.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 10mg / kg, and the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction. Four beds are set in the hydrocracking reaction zone, and the reaction conditions are liquid hourly volume space velocity of 2.0h -1, the reaction temperature is 372℃, the reaction pressure is 9.2MPa, the hydrogen-to-oil volume ratio is 800, the single-pass conversion rate is 60%, and the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction is circulated back to the hydrofining reaction zone for further reaction. The liquefied gas and light naphtha are circulated back to the hydrocracking reaction zone for further reaction, wherein the circulating liquefied gas accounts for 9% of the weight of the heavy naphtha, and the circulating light naphtha accounts for 15% of the weight of the heavy naphtha.

[0045] Comparative Example 1

[0046] This comparative example is operated according to the conventional single-stage full-cycle process to process the crude oil 1 in Table 1. The hydrofining reaction zone is filled with FF-66 and the hydrocracking reaction zone is filled with FC-50. The crude oil and hydrogen are fed from the top of the hydrofining reaction zone. The liquid hourly volume space velocity of the hydrofining reaction zone is 2.0 h -1 The reaction temperature is 348°C, the reaction pressure is 9.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 3mg / kg, and the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction. Four beds are set in the hydrocracking reaction zone. The reaction conditions are liquid hourly volume space velocity of 2.0h -1 , reaction temperature is 370℃, reaction pressure is 9.2MPa, hydrogen-oil volume ratio is 800, single-pass conversion rate is 60%, the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction is recycled back to the hydrofining reaction zone for further reaction.

[0047] Comparative Example 2

[0048] In this comparative example, the raw oil 1 in Table 1 was processed according to the method of the present invention. The hydrofining reaction zone was filled with FF-66 and the hydrocracking reaction zone was filled with FC-50. The liquid hourly volume space velocity in the hydrofining reaction zone was 2.0 h -1 The reaction temperature is 348°C, the reaction pressure is 9.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 3mg / kg, and the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction. Four beds are set in the hydrocracking reaction zone. The reaction conditions are liquid hourly volume space velocity of 2.0h -1, reaction temperature is 370℃, reaction pressure is 9.2MPa, hydrogen-oil volume ratio is 800, single-pass conversion rate is 60%, the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction, liquefied gas and light naphtha are circulated back to the hydrocracking reaction zone for further reaction, of which the circulating liquefied gas accounts for 8% of the weight of the heavy naphtha, and the circulating light naphtha accounts for 14% of the weight of the heavy naphtha.

[0049] Comparative Example 3

[0050] In this comparative example, the raw oil 1 in Table 1 was processed according to the method of the present invention. The hydrofining reaction zone was filled with FF-66 and the hydrocracking reaction zone was filled with FC-50. The liquid hourly volume space velocity in the hydrofining reaction zone was 2.0 h -1 The reaction temperature is 348°C, the reaction pressure is 9.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 3mg / kg, and the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction. Four beds are set in the hydrocracking reaction zone. The reaction conditions are liquid hourly volume space velocity of 2.0h -1 , the reaction temperature is 370℃, the reaction pressure is 9.2MPa, the hydrogen-to-oil volume ratio is 800, the single-pass conversion rate is 60%, and the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction is circulated back to the hydrocracking reaction zone for further reaction. The liquefied gas and light naphtha are circulated back to the hydrorefining reaction zone for further reaction, wherein the circulating liquefied gas accounts for 8% of the weight of the heavy naphtha, and the circulating light naphtha accounts for 14% of the weight of the heavy naphtha.

[0051] Comparative Example 4

[0052] This comparative example is based on the method of the present invention and Figure 1 The process operation is to process the crude oil 1 in Table 1, the hydrotreating reaction zone is filled with FF-66, the hydrocracking reaction zone is filled with FC-50, and the liquid hourly volume space velocity in the hydrotreating reaction zone is 2.0h -1 The reaction temperature is 348°C, the reaction pressure is 9.5MPa, the hydrogen-oil volume ratio is 600, the nitrogen content of the oil generated in the refining reaction zone is controlled to be 3mg / kg, and the hydrorefined oil generated after the raw oil reacts in the hydrorefining reaction zone enters the top of the hydrocracking reactor for hydrocracking reaction. Four beds are set in the hydrocracking reaction zone. The reaction conditions are liquid hourly volume space velocity of 2.0h -1, the reaction temperature is 370℃, the reaction pressure is 9.2MPa, the hydrogen-to-oil volume ratio is 800, the single-pass conversion rate is 60%, and the product enters the subsequent separation and fractionation system to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel components. The diesel fraction is circulated back to the hydrorefining reaction zone for further reaction. The liquefied gas and light naphtha are circulated back to the hydrocracking reaction zone for further reaction, wherein the circulating liquefied gas accounts for 3% of the weight of the heavy naphtha, and the circulating light naphtha accounts for 5% of the weight of the heavy naphtha.

[0053] Table 1 Raw oil properties

[0054]

[0055]

[0056] *The blend contains 30wt% catalytic diesel and 70wt% straight run diesel.

[0057] Table 2 Main physical and chemical properties of catalysts

[0058] project FF-66 FC-50 Chemical composition Mo-Ni W-Ni Physical properties Appearance and shape Shamrock Cylindrical Bar Crushing strength, N / cm ≥150 ≥150 Particle diameter, mm 1.0～1.4 1.4～1.8 Molecular sieve type / content, wt% -- Y-type molecular sieve / 20

[0059] Table 3 Main reaction conditions for each example

[0060]

[0061] Table 4 Comparison of the effects obtained in each case

[0062]

[0063]

Claims

1. A hydrocracking method for producing heavy naphtha, the method comprising a hydrofining reaction zone and a hydrocracking reaction zone, the process comprising: The diesel feedstock, hydrogen and circulating oil are mixed and passed through a hydrofining reaction zone to carry out a hydrofining reaction, wherein the nitrogen content of the effluent from the hydrofining reaction zone is controlled to be below 25 mg / kg, and the effluent from the hydrofining reaction zone is mixed with part of the liquefied gas and part of the light naphtha and then enters a hydrocracking reaction zone for reaction, and the effluent from the hydrocracking reaction zone is separated and fractionated to obtain dry gas, liquefied gas, light naphtha, heavy naphtha and diesel, wherein the diesel is circulated back to the hydrofining reaction zone as the circulating oil, and part of the liquefied gas and part of the light naphtha are circulated back to the hydrocracking reaction zone; Based on the output of heavy naphtha, the mass fraction of the circulating volume of liquefied gas to the output of heavy naphtha is 7wt%~10wt%; the mass fraction of the circulating volume of light naphtha to the output of heavy naphtha is 13wt%~17wt%; The hydrocracking reaction zone is provided with more than three hydrocracking catalyst beds.

2. The method according to claim 1, characterized in that A hydrofining reaction is carried out through the hydrofining reaction zone, and the nitrogen content of the effluent from the hydrofining reaction zone is controlled to be 1-15 mg / kg.

3. The method according to claim 1, characterized in that The hydrotreating reaction zone is loaded with a hydrotreating catalyst, wherein the hydrotreating catalyst has a content of 12% to 37% of Group VIB metal in terms of oxide and a content of 0.5% to 7.5% of Group VIII metal in terms of oxide based on the weight of the catalyst.

4. The method according to claim 3, characterized in that The hydrotreating reaction zone is loaded with a hydrotreating catalyst, wherein the hydrotreating catalyst has a content of 15% to 32% of Group VIB metal in terms of oxide and a content of 1% to 7% of Group VIII metal in terms of oxide based on the weight of the catalyst.

5. The method according to claim 1, characterized in that The hydrocracking reaction zone is filled with a hydrocracking catalyst, with the hydrogenation component content being 12wt% to 42wt% in terms of oxide and the molecular sieve content being 1wt% to 30wt% based on the weight of the catalyst; the hydrogenation component being selected from one or more of Group VIB, Group VIIB, Group VIII metals, metal oxides or metal sulfides.

6. The method according to claim 5, characterized in that The hydrocracking reaction zone is filled with a hydrocracking catalyst, and the content of the hydrogenation component is 18wt% to 38wt% in terms of oxide, based on the weight of the catalyst.

7. The method according to claim 1, characterized in that The diesel raw material is one or more of straight-run diesel, catalytic diesel, ebullated-bed hydrogenated diesel and coking diesel.

8. The method according to claim 7, characterized in that The diesel raw material is a raw material containing straight-run diesel, and the straight-run diesel accounts for more than 25wt% of the total mass of the diesel raw material.

9. The method according to claim 7, characterized in that: The straight-run diesel has a nitrogen content of less than 0.04 wt%, an initial distillation point of 150-250° C., a final distillation point of 310-380° C., and an aromatics content of 5 wt%-35 wt%.

10. The method according to claim 9, characterized in that The straight-run diesel has a nitrogen content of less than 0.01 wt% and an aromatics content of 10 wt% to 30 wt%.

11. The method according to claim 9, characterized in that The straight-run diesel has a nitrogen content of 0.001 wt% to 0.0099 wt%.

12. The method according to claim 7, characterized in that Catalytic diesel is blended into the diesel raw material, and the catalytic diesel accounts for less than 65wt% of the total mass of the diesel raw material.

13. The method according to claim 12, characterized in that The initial boiling point of the catalytic diesel is 110-230°C, the final boiling point is 310-390°C, and the aromatic content is above 65wt%; the density of the catalytic diesel is 0.91g·cm -3 above.

14. The method according to claim 13, characterized in that The initial boiling point of the catalytic diesel is 120-220°C, the final boiling point is 320-380°C, and the aromatic content is above 70wt%. The density of the catalytic diesel is 0.92g·cm -3 above.

15. The method according to claim 13, characterized in that The aromatic content of the catalytic diesel is 71wt% to 90wt%; the density of the catalytic diesel is 0.92g·cm -3 ~0.97g·cm -3 .

16. The method according to claim 1, characterized in that The process conditions of the hydrotreating reaction zone are as follows: average reaction temperature 280℃~400℃, inlet hydrogen-oil volume ratio 200:1~900:1, operating pressure 6.0MPa~10.0MPa, liquid hourly volume space velocity 0.5h -1 ~5.0h -1 .

17. The method according to claim 16, characterized in that The process conditions of the hydrotreating reaction zone are as follows: average reaction temperature 300℃~380℃, inlet hydrogen-oil volume ratio 300:1~800:1, operating pressure 6.5MPa~9.5MPa, liquid hourly volume space velocity 0.8h -1 ~4.5h -1 .

18. The method according to claim 1, characterized in that The hydrocracking reaction zone is provided with 4 to 5 hydrocracking catalyst beds.

19. The method according to claim 1, characterized in that The process conditions of the hydrocracking reaction zone are as follows: average reaction temperature 310℃~410℃, inlet hydrogen oil volume ratio 400:1~1100:1, operating pressure 6.0MPa~10.0MPa, liquid hourly volume space velocity 0.5h -1 ~5.0h -1 .

20. The method according to claim 19, characterized in that The process conditions of the hydrocracking reaction zone are as follows: average reaction temperature 320℃~400℃, inlet hydrogen oil volume ratio 500:1~1000:1, operating pressure 6.5MPa~9.5MPa, liquid hourly volume space velocity 0.8h -1 ~4.5h -1 .

21. The method according to claim 1, characterized in that The effluent from the hydrocracking reaction zone is separated by a separation system, and hydrogen is separated from the top of the separation system and circulated back to the hydrofining reaction zone and the hydrocracking reaction zone as circulating hydrogen.

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