A two-stage hydrocracking method for producing more chemical raw materials

Abstract

The present invention discloses a two-stage hydrocracking method for producing more chemical raw materials. The method comprises: the raw oil and hydrogen first enter the first hydrogenation reaction zone in the two stages for reaction, the one-way conversion rate of the first hydrogenation reaction zone is controlled to be 70% to 85%, the effluent of the first hydrogenation reaction zone enters a high-pressure gas-liquid phase separator with a pressure lower than that of the first hydrogenation reaction zone and a temperature of 80 to 100°C, so that the mass ratio of hydrogen to hydrocarbons in the gas phase component obtained at the top of the high-pressure gas-liquid phase separator is 1.20 to 1.70, the liquid phase component obtained at the bottom is separated and fractionated to obtain light hydrocarbons, light naphtha, heavy naphtha, diesel and tail oil, the diesel and the gas phase component at the top of the high-pressure gas-liquid phase separator enter the second hydrogenation reaction zone in the two stages for reaction, the one-way conversion rate of the second hydrogenation reaction zone is controlled to be 40% to 80%, and the second hydrogenation reaction zone is subjected to the separation and fractionation. The method of the present invention can achieve the purpose of increasing the production of high-quality chemical raw materials by only slightly adjusting the process, and has the advantages of long-term stable operation.

Description

Technical Field

[0001] The method of the invention relates to a two-stage hydrocracking method, specifically a two-stage hydrocracking method for producing more chemical raw materials. Background Art

[0002] At present, the demand for chemical oil in China is growing very fast, much faster than the growth rate of refined oil, and the contradiction between supply and demand of chemical oil such as ethylene raw materials and aromatic raw materials is also prominent. Therefore, petrochemical enterprises must combine petrochemical refining process units in accordance with the principle of oil-chemical integration, reasonably allocate resources, and maximize the supply of high-quality chemical raw materials such as ethylene cracking and aromatics to meet the needs of the rapid increase in petrochemical development and maximize the overall benefits of the enterprise. The combined process with hydrocracking as the core production can provide a large amount of chemical raw materials by processing vacuum wax oil and heavy naphtha with high aromatic potential that is not suitable for ethylene raw materials. It is the bridge and core of the organic combination of oil and chemical.

[0003] There are three basic hydrocracking process flows, namely single-stage, single-stage series and two-stage. To meet the diversified market demand, hydrocracking patent holders have launched new hydrocracking process technologies derived from the three basic process flows, such as reverse series, staged feeding and parallel feeding, but their core is also the combination optimization of conventional processes.

[0004] Since fuel oil dominated the market demand in the early years, most of the hydrocracking units at that time adopted a single-stage double-dose or single-stage series process. With the change of capital structure in recent years, more and more downstream capital has been injected into the refining and chemical industry. Producing high-quality, cheap and large quantities of chemical raw materials has become a new direction for the development of the petrochemical industry. For example, many private refineries built recently have a single main goal of chemical raw material demand, which stimulates the change of market product structure. Under this impact, for many refining and processing units, the hydrocracking technology that can produce chemical raw materials has received more and more attention. If we distinguish carefully, the two-stage hydrocracking process has become the most preferred hydrocracking process due to its high chemical raw material yield. Chemical raw materials mainly include ethylene and reforming materials. How to further improve the total yield of the two has become the key judgment of the advancement of hydrocracking technology. Therefore, the technical means of maximizing the production of chemical raw materials has become the goal that "refiners" are tirelessly pursuing.

[0005] CN101089141A discloses a two-stage hydrocracking method. Using VGO and / or other heavy fraction oil as raw material, a two-stage process flow is adopted to obtain various high-quality clean products under hydrocracking operation conditions. At least one catalyst in the pretreatment reaction zone is a bulk catalyst, and the bulk catalyst is a composite oxide Ni x Wy O z The weight ratio of Ni and MoO3 is 1:10 to 10:1. x W y O z The oxide MoO3 accounts for 40% to 100% of the total weight of the catalyst composition. The method can effectively reduce the operation severity of a pretreatment reaction zone, increase the processing capacity of the device, extend the service life of the catalyst and improve the product quality, but its main purpose is to produce clean fuel oil.

[0006] CN1952067A discloses a two-stage hydrocracking method for producing high-quality middle distillate oil. The raw oil is mixed with hydrogen and directly enters the first stage hydrocracking reactor. The first stage hydrocracking reactor adopts a single stage two-agent, that is, two catalysts are used in the single stage hydrocracking process. The upper part is loaded with a refining agent, and the lower part is loaded with a cracking agent. The tail oil of the first stage is circulated to the inlet of the second stage hydrocracking reactor. This method is mainly used for the hydrocracking process of producing high-quality middle distillate oil using various heavy distillate oils as raw materials.

[0007] In the above technologies, either the severity of the operation of a pre-treatment reaction zone is reduced to produce high-quality clean fuel, or various heavy distillate oils are used as raw materials to produce high-quality middle distillate oils. However, there is still room for further improvement in how to increase the total yield of chemical raw materials. Summary of the invention

[0008] The inventor of the present invention has found through extensive research that by adopting a two-stage hydrocracking method, the conversion depth of the hydrocracking in the first stage (i.e., the first hydrogenation reaction zone) and the mass ratio of hydrogen to hydrocarbons in the gas phase component at the top of the high-pressure gas-liquid phase separator are controlled. Due to the specific hydrogen-to-hydrocarbon ratio, hydrogen sulfide and ammonia contained in this gas phase component, this gas phase component enters the second stage (i.e., the second hydrogenation reaction zone) as a gas phase feed, and cooperates with the circulating non-ideal components as liquid phase feed for hydrocracking, which not only improves the performance of the second stage hydrocracking catalyst, suppresses the occurrence of adverse reactions, and promotes the catalytic performance of the target product, but also cooperates with the optimized reaction atmosphere, thereby jointly promoting the purpose of suppressing adverse reactions and increasing the production of chemical raw materials, and at the same time can improve the operation cycle of the device, thereby realizing the present invention. When the conventional two-stage hydrocracking method is adopted, the existing hot high-fraction gas is directly used to be injected into the second stage reactor. Due to the pressure difference, it will not be able to circulate back to the existing high-fraction, and the parameters of the high-pressure separator are completely different from the preset parameters of the present invention. Therefore, auxiliary facilities must be added, but the existing equipment is unable to pressurize the mixed gas-liquid phase under high sulfur, high nitrogen, high hydrocarbon and high temperature conditions, and the light components cannot be discharged from the existing devices, so it is difficult to directly utilize high-fraction gas in the current technical field.

[0009] The present invention provides a two-stage hydrocracking method for producing more chemical raw materials. The method can achieve the purpose of increasing the production of high-quality chemical raw materials by only slightly adjusting the process, and has the advantage of long-term stable operation.

[0010] The present invention provides a two-stage hydrocracking method for producing more chemical raw materials, wherein the method includes a first hydrogenation reaction zone and a second hydrogenation reaction zone, and the process includes: the raw oil and hydrogen first enter the first hydrogenation reaction zone for reaction, and the single-pass conversion rate of the first hydrogenation reaction zone is controlled to be 70% to 85%, and the effluent of the first hydrogenation reaction zone enters a high-pressure gas-liquid phase separator, the pressure controlled in the high-pressure gas-liquid phase separator is lower than the reaction pressure of the first hydrogenation reaction zone, and the temperature is 80 to 100°C, preferably 85 to 95°C, so that the gas phase components obtained at the top of the high-pressure gas-liquid phase separator The mass ratio of hydrogen to hydrocarbons is 1.20 to 1.70, preferably 1.25 to 1.65. All heavy liquid components obtained at the bottom of the high-pressure gas-liquid phase separator enter the separation and fractionation system to obtain light hydrocarbons, light naphtha, heavy naphtha, diesel and tail oil. The diesel obtained by fractionation and the gaseous components obtained at the top of the high-pressure gas-liquid phase separator enter the second hydrogenation reaction zone for reaction. The single-pass conversion rate of the second hydrogenation reaction zone is controlled to be 40% to 80%, preferably 60% to 70%. The effluent from the second hydrogenation reaction zone enters the separation and fractionation system.

[0011] In the above hydrocracking method, the upper part of the first hydrogenation reaction zone is the hydrogenation pretreatment section, and the lower part is the hydrocracking section, and the upper part of the second hydrogenation reaction zone is the hydrocracking section, and the lower part is the hydrogenation post-treatment section.

[0012] In the above hydrocracking method, heavy naphtha can be used as a chemical raw material for catalytic reforming, and tail oil can be used as a chemical raw material for steam cracking to produce ethylene.

[0013] In the above hydrocracking method, a fixed bed hydrogenation process is adopted, and both the first hydrogenation reaction zone and the second hydrogenation reaction zone adopt an upper feeding and lower discharging operation mode.

[0014] In the above hydrocracking method, the fresh feedstock oil can be selected from the straight run or secondary fractions obtained by processing crude oils of different basic properties (for example, at least one of cycloalkyl, intermediate, and paraffinic crude oils), such as wax oil. The properties of the wax oil are as follows: the initial distillation point is 250-350°C, the final distillation point is 460-560°C, preferably 470-550°C, and the density is not more than 0.93 g / cm 3 , preferably not more than 0.92 g / cm 3 , further 0.87~0.92g / cm 3The sulfur content by mass is not less than 0.2%, preferably 0.2% to 2%, and the nitrogen content by mass is not less than 0.05%, preferably not less than 0.08%, preferably 0.08% to 0.2%.

[0015] In the above hydrocracking method, in the first hydrogenation reaction zone, the hydropretreatment section is loaded with a hydropretreatment catalyst, and the hydrocracking section is loaded with a hydrocracking catalyst; in the second hydrogenation reaction zone, the hydrocracking section is loaded with a hydrocracking catalyst, and the hydroposttreatment section is loaded with a hydroposttreatment catalyst.

[0016] In the above hydrocracking method, the hydrogenation pretreatment catalyst and the hydrogenation post-treatment catalyst can adopt the hydrogenation pretreatment catalyst, and various conventional commercial catalysts that have been industrialized can be selected, or they can be prepared according to the actual needs of the scheme in accordance with the conventional knowledge in the field. The hydrogenation pretreatment catalyst includes a carrier and a hydrogenation active metal; the hydrogenation active metal includes a Group VIB metal (such as tungsten and / or molybdenum) and a Group VIII metal (such as nickel and / or cobalt); the carrier is an inorganic refractory oxide, which can be selected from alumina, amorphous silica-alumina, silicon dioxide, titanium oxide, etc., preferably alumina. Based on the weight of the catalyst, the content of the Group VIB metal in terms of oxide is 10% to 30%, preferably 15% to 30%; the content of the Group VIII metal in terms of oxide is 0.5% to 7.5%, preferably 1.5% to 6.5%. Conventional commercial catalysts such as FF-36, FH-UDS, FF-66 and other hydrocracking pretreatment catalysts developed by Fushun Petrochemical Research Institute (FRIPP). The hydrogenation pretreatment catalyst and the hydrogenation post-treatment catalyst may be the same or different, and the same catalyst is preferred in the present invention.

[0017] In the above hydrocracking method, the hydrocracking catalysts contained in the two hydrogenation reaction zones can be selected from various existing commercial catalysts, or specific hydrocracking catalysts can be prepared according to the common sense in the field as needed. Generally speaking, the hydrocracking catalysts in the two hydrogenation reaction zones can be the same or different, and the present invention preferably uses the same catalyst. The hydrocracking catalyst includes a cracking component and a hydrogenation active metal component; the hydrogenation active metal is selected from at least one of the non-precious metals of Group VIB, Group VII or Group VIII, preferably one or more of iron, chromium, molybdenum, tungsten, cobalt, and nickel; the cracking component includes 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 hydrocracking catalyst also contains a binder, which is usually aluminum oxide or silicon oxide. Based on the weight of the catalyst, the content of the hydrogenation active metal component in terms of oxide is 9% to 31%, preferably 14% to 26%, and the content of the molecular sieve is 40% to 65%, preferably 50% to 65%. The main commercial hydrocracking catalysts include FC-52, FC-46, FC-24 and other catalysts developed by FRIPP.

[0018] In the above hydrocracking method, the operating conditions of the first hydrogenation reaction zone are as follows:

[0019] Hydrogenation pretreatment section: reaction temperature 300℃~440℃, hydrogen-oil volume ratio 500:1~1100:1, operating pressure 11.0MPa~17.0MPa, liquid hourly volume space velocity 0.3h -1 ~5.0h -1 Preferably, the reaction temperature is 320°C to 410°C, the hydrogen-to-oil volume ratio is 600:1 to 1000:1, the operating pressure is 12.0MPa to 16.0MPa, and the liquid hourly volume space velocity is 0.4h -1 ~4.0h -1 .

[0020] Hydrocracking section: reaction temperature 320℃~450℃, hydrogen-oil volume ratio 800:1~1500:1, operating pressure 10.5MPa~16.5MPa, liquid hourly volume space velocity 0.4h -1 ~4.5h -1 Preferably, the reaction temperature is 330°C to 400°C, the hydrogen-to-oil volume ratio is 900:1 to 1400:1, the operating pressure is 11.0MPa to 16.0MPa, and the liquid hourly volume space velocity is 0.5h -1 ~4.0h -1 .

[0021] In the above hydrocracking method, in the second reaction zone, the loading volume ratio of the hydrocracking catalyst to the hydrogenation post-treatment catalyst is 7 to 13, preferably 8 to 12, and the operating conditions of the second hydrogenation reaction zone are: reaction temperature 260°C to 380°C, hydrogen-oil volume ratio 700:1 to 1400:1, operating pressure 9.5MPa to 15.5MPa, liquid hourly volume space velocity 0.5h -1 ~5.0h -1 Preferably, the reaction temperature is 280°C to 360°C, the hydrogen-to-oil volume ratio is 800:1 to 1300:1, the operating pressure is 10.0MPa to 15.0MPa, and the liquid hourly volume space velocity is 0.6h -1 ~5.0h -1 The hydrogen-to-oil volume ratio refers to the volume ratio of hydrogen gas in the mixed feed to the volume ratio of liquid feed.

[0022] In the above hydrocracking method, the one-way conversion rate (by mass) must be controlled for both the first hydrogenation reaction zone and the second hydrogenation reaction zone, and a certain temperature point must be corresponded when the conversion rate is involved. In the present invention, the temperature point corresponding to the one-way conversion rate of the first hydrogenation reaction zone is 330°C to 370°C, preferably 340°C to 360°C, and its depth can be achieved by adjusting the reaction temperature of the hydrocracking section of the first hydrogenation reaction zone; the temperature point corresponding to the one-way conversion rate of the second hydrogenation reaction zone is 175°C to 177°C, and its depth can be achieved by adjusting the reaction temperature of the hydrocracking section of the second hydrogenation reaction zone.

[0023] In the above-mentioned hydrocracking method, the high-pressure gas-liquid phase separator can make the gas phase components in the separator coexist by controlling the conditions, i.e., adjusting the temperature and pressure, and only plays a one-time separation role; the gas phase components in the gas-liquid phase separator are discharged from the top, and the heavy liquid phase components are discharged from the bottom, wherein the gas phase components include hydrogen, hydrogen sulfide, ammonia and light hydrocarbons, wherein the light hydrocarbons mainly contain dry gas, liquefied gas and light naphtha fractions, the coexistence of gas phase components means that hydrogen sulfide, ammonia and light hydrocarbons will not precipitate and will not change in phase state, and the heavy liquid phase components include heavy naphtha, diesel and tail oil effluent after separation. The inventor found through experimental research that the mass ratio of hydrogen component to light hydrocarbons in the gas phase components at the top of the high-pressure gas-liquid phase separator is controlled to be 1.20-1.70, preferably 1.25-1.65, and the gas phase components enter the second hydrogenation reaction zone as gas phase feed, which can play a good promoting role, is conducive to increasing the production of chemical raw materials, and can operate stably for a long period of time. The operating conditions of the high-pressure gas-liquid phase separator are as follows: pressure is 10.0MPa-16.0MPa, preferably 10.5MPa-15.5MPa, temperature is 80℃-100℃, preferably 85℃-95℃, and the high-pressure gas-liquid phase separator is a gas-liquid flash separation device.

[0024] In the above hydrocracking method, the separation and fractionation units are common knowledge of technicians in this field and do not need to be described in detail. The products discharged from the system of the method of the present invention mainly include dry gas, liquefied gas, light naphtha, heavy naphtha and tail oil products. The intermediate distillate oil is separated by the fractionation tower and all enters the second hydrogenation reaction zone as liquid feed, and is processed together with the gas phase components at the top of the high-pressure gas-liquid phase separator, and converted into chemical raw materials through hydrocracking reaction. The liquid phase components obtained by the high-pressure gas-liquid phase separator and the effluent of the second hydrogenation reaction zone share a set of separation and fractionation systems.

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

[0026] The hydrocracking method of the present invention adopts a two-stage hydrocracking process, by adding a high-pressure gas-liquid phase separator after the first hydrogenation reaction zone, controlling the hydrogen-to-hydrocarbon ratio in the gas phase obtained at the top of the high-pressure gas-liquid phase separator, and using this gas phase as the gas phase feed of the second hydrogenation reaction zone, using the circulating intermediate distillate oil as the liquid phase feed of the second hydrogenation reaction zone, and utilizing hydrogen sulfide, ammonia, and hydrogen with a specific hydrogen-to-hydrocarbon ratio and coexisting gas of light hydrocarbon components in the gas phase, not only can the performance of the second-stage hydrocracking catalyst be improved, the occurrence of adverse reactions can be suppressed, and the catalytic performance of the target product can be promoted, and the optimized reaction atmosphere can be used to jointly promote the suppression of adverse reactions and increase the yield of the target product chemical raw materials, extend the operation cycle of the device, and improve the overall reaction effect. The present invention uses existing logistics for reasonable configuration, makes full use of the characteristics of different reaction stages, and only reasonably configures the logistics of the first and second hydrogenation reaction zones, does not require the introduction of additional logistics, and can not only operate stably for a long period of time, but also achieve the purpose of producing chemical raw materials in the largest amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the principle flow of a two-stage hydrocracking method for producing more chemical raw materials according to the present invention;

[0028] Figure 2 It is a schematic diagram of the principle flow chart of the conventional two-stage hydrocracking method. DETAILED DESCRIPTION

[0029] 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.

[0030] In the present invention, the chemical raw materials include heavy naphtha as reforming feed, whose initial distillation point is 60°C to 90°C and whose final distillation point is 160°C to 190°C, and also include tail oil as raw material for steam cracking to produce ethylene, whose initial distillation point is 250°C to 380°C and whose final distillation point is 400°C to 500°C.

[0031] In the present invention, the middle distillate oil refers to the diesel fraction, which has an initial distillation point of 160°C to 190°C and a final distillation point of 360°C to 380°C.

[0032] In the present invention, the definition of conversion rate is:

[0033] Conversion rate of the first hydrogenation reaction zone (%) = [1-(unconverted oil amount / fresh feed amount)] × 100%;

[0034] The conversion rate of the second hydrogenation reaction zone (%) = {1-[circulating oil amount / (fresh feed amount+circulating oil amount)]}×100%.

[0035] like Figure 1As shown, the process flow of the present invention is as follows:

[0036] The feedstock 1 and the circulating hydrogen 16 are mixed and then enter the first hydrogenation reaction zone 2 filled with a hydrogenation pretreatment catalyst and a hydrocracking catalyst for hydrogenation pretreatment and hydrocracking reaction. The reaction effluent 3 enters the high-pressure separator 4 for separation of gas phase and liquid phase. A gas phase component 5 is obtained at the top and a liquid phase component 6 is obtained at the bottom. The liquid phase component 6 enters the subsequent separation system 15. The discharged liquid phase logistics 17 enters the fractionation system 7. In the fractionation system 7, light hydrocarbons 8, light naphtha 9, heavy naphtha 10, diesel 11 and tail oil 12 are discharged from top to bottom in sequence. The diesel 11 is circulated and mixed with the gas phase component 5 and then enters the second hydrogenation reaction zone 13 for hydrocracking reaction. The reaction effluent 14 enters the subsequent separation system 15. The obtained gas phase 16 is mixed with the feedstock 1 as circulating hydrogen to react again. The obtained liquid phase logistics 17 enters the fractionation system 7 and then undergoes product fractionation and circulation again, thereby achieving increased production of chemical raw materials. Among them, heavy naphtha can be used as a raw material for catalytic reforming, and tail oil can be used as a raw material for steam cracking to produce ethylene.

[0037] like Figure 2 The process flow of conventional two-stage hydrocracking is as follows:

[0038] The feedstock 1 is mixed with the recycled hydrogen 16 and then enters the first hydrogenation reaction zone 2 filled with a hydrogenation pretreatment catalyst and a hydrocracking catalyst for hydrogenation pretreatment and hydrocracking reaction. The reaction effluent 3 enters the separation system 15 for separation to obtain the circulating hydrogen 16 and the liquid phase stream 17. The liquid phase stream 17 enters the fractionation system 7 for fractionation. In the fractionation system 7, light hydrocarbons 8, light naphtha 9, heavy naphtha 10, diesel 11 and tail oil 12 are obtained at the top. The diesel 11 is mixed with the circulating hydrogen 16 and then circulated back to the second hydrogenation reaction zone 13, and enters the second hydrogenation reaction zone 13 filled with a hydrocracking catalyst and a hydrogenation post-treatment catalyst for reaction. The reaction effluent 14 enters the separation system 15, and the obtained gas phase 16 is mixed with the feedstock 1 as circulating hydrogen to react again. The obtained liquid phase stream 17 enters the fractionation system 7 and then undergoes product fractionation and circulation again.

[0039] The method of the present invention is further described below with reference to embodiments and comparative examples.

[0040] In the present invention, unless otherwise specified, % refers to mass fraction.

[0041] In the embodiments of the present invention and the comparative examples, the conversion rate temperature cut point corresponding to the first hydrogenation reaction zone is 350°C, and the conversion rate temperature cut point corresponding to the second hydrogenation reaction zone is 177°C.

[0042] In the embodiments and comparative examples of the present invention, the distillation range of the middle distillate diesel is 177-350°C, and the tail oil cut point is 350°C.

[0043] The embodiment of the present invention is according to Figure 1 The comparative example was operated according to the conventional two-stage hydrocracking process as shown in Figure 2 The properties of the raw oil involved are shown in Table 1, the main physical properties of various catalysts are shown in Table 2, the main operating conditions are shown in Table 3 and Table 4, the comparison of their advantages and effects is shown in Table 5, and the properties of the heavy naphtha and tail oil obtained in each example are shown in Table 6.

[0044] Example 1

[0045] The raw material 1 in Table 1 was used as the raw material oil. The first hydrogenation reaction zone was graded from top to bottom with FF-66 hydrogenation pretreatment catalyst and FC-24 hydrocracking catalyst (the loading volume ratio of the two was 5:3), and the second hydrogenation reaction zone was loaded with FC-24 (hydrocracking catalyst) and FF-66 (hydrogenation post-treatment catalyst) (the loading volume ratio of the two was 8:1); the reaction temperature of the pretreatment section of the first hydrogenation reaction zone was 381°C, the reaction pressure was 14.0 MPa, the hydrogen-oil volume ratio was 700:1, and the liquid hourly volume space velocity was 0.9 h -1 The reaction temperature of the cracking section is 367°C, the reaction pressure is 13.5MPa, the hydrogen-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1 ; Control the conversion rate at >350℃ to 80%, the reaction effluent enters the high-pressure gas-liquid separator, the operating pressure is 13.5MPa, the temperature is 95℃, and the mass ratio of hydrogen to hydrocarbons in the top gas phase is controlled to be 1.46. The liquid phase discharged from the bottom of the separator enters the separation and fractionation system for component separation, and the liquid intermediate distillate oil in the middle of the fractionation system and the gas phase at the top of the separator enter the second hydrogenation reaction zone together, the reaction temperature is 323℃, the reaction pressure is 13.0MPa, the hydrogen-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1 , the single-pass conversion rate of the second stage>177℃ is controlled to be 65%, and the liquid phase after the reaction enters the above-mentioned separation and distillation system to obtain light hydrocarbons, light naphtha, heavy naphtha, middle distillate diesel and tail oil, among which the middle distillate oil is used as circulating oil, the heavy naphtha is used as a chemical raw material, and the tail oil is used as a raw material for steam cracking to produce ethylene.

[0046] Example 2

[0047] The raw material 1 in Table 1 was used as the feed. The first hydrogenation reaction zone was graded from top to bottom with FF-66 hydrogenation pretreatment catalyst and FC-24 hydrocracking catalyst (the filling volume ratio of the two was 5:3), and the second hydrogenation reaction zone was filled with FC-24 (hydrocracking catalyst) and FF-66 (hydrogenation post-treatment catalyst) (the filling volume ratio of the two was 8:1); the reaction temperature of the pretreatment section of the first hydrogenation reaction zone was 379°C, the reaction pressure was 15.5MPa, the hydrogen-oil volume ratio was 800:1, and the liquid hourly volume space velocity was 0.9h -1 The reaction temperature of the cracking section is 365°C, the reaction pressure is 15.0MPa, the hydrogen-oil volume ratio is 1000:1, and the liquid hourly volume space velocity is 1.5h -1 , control> 350℃ conversion rate to 80%, the reaction effluent enters the high-pressure gas-liquid separator, its operating pressure is 15.0MPa, the temperature is 90℃, and the mass ratio of hydrogen to hydrocarbons in the top gas phase is controlled to be 1.51. The liquid phase discharged from the bottom of the separator enters the separation and fractionation system for component separation. The liquid intermediate distillate oil in the middle of the fractionation system and the gas phase at the top of the separator enter the second hydrogenation reaction zone together, the reaction temperature is 321℃, the reaction pressure is 14.5MPa, the hydrogen-oil volume ratio is 1000:1, and the liquid hourly volume space velocity is 1.5h -1 , the single-pass conversion rate of the second stage>177℃ is controlled to be 62%. The liquid phase after the reaction enters the above-mentioned separation and distillation system to obtain light hydrocarbons, light naphtha, heavy naphtha, middle distillate diesel and tail oil, among which the middle distillate oil is used as circulating oil, the heavy naphtha is used as a chemical raw material, and the tail oil is used as a raw material for steam cracking to produce ethylene.

[0048] Example 3

[0049] The raw material 1 in Table 1 was used as the feed. The first hydrogenation reaction zone was graded from top to bottom with FF-66 hydrogenation pretreatment catalyst and FC-24 hydrocracking catalyst (the filling volume ratio of the two was 5:3), and the second hydrogenation reaction zone was filled with FC-24 (hydrocracking catalyst) and FF-66 (hydrogenation post-treatment catalyst) (the filling volume ratio of the two was 8:1); the reaction temperature of the pretreatment section of the first hydrogenation reaction zone was 387°C, the reaction pressure was 12.5 MPa, the hydrogen-oil volume ratio was 800:1, and the liquid hourly volume space velocity was 1.2 h -1 The reaction temperature of the cracking section is 375°C, the reaction pressure is 12.0 MPa, the hydrogen-oil volume ratio is 1000:1, and the liquid hourly volume space velocity is 2.0 h -1, control> 350℃ conversion rate to 75%, the reaction effluent enters the high-pressure gas-liquid separator, its operating pressure is 11.5MPa, temperature is 90℃, and the mass ratio of hydrogen to hydrocarbons in the top gas phase is controlled to be 1.44. The liquid phase discharged from the bottom of the separator enters the separation and fractionation system for component separation. The liquid intermediate distillate oil in the middle of the fractionation system and the gas phase at the top of the separator enter the second hydrogenation reaction zone together, the reaction temperature is 334℃, the reaction pressure is 11.0MPa, the hydrogen-oil volume ratio is 1000:1, and the liquid hourly volume space velocity is 2.0h -1 , the single-pass conversion rate of the second stage>177℃ is controlled to be 68%, and the liquid phase after the reaction enters the above-mentioned separation and distillation system to obtain light hydrocarbons, light naphtha, heavy naphtha, middle distillate diesel and tail oil, among which the middle distillate oil is used as circulating oil, the heavy naphtha is used as a chemical raw material, and the tail oil is used as a raw material for steam cracking to produce ethylene.

[0050] Example 4

[0051] The raw material 2 in Table 1 was used as the feed. The first hydrogenation reaction zone was graded from top to bottom with FF-66 hydrogenation pretreatment catalyst and FC-24 hydrocracking catalyst (the loading volume ratio of the two was 5:3), and the second hydrogenation reaction zone was loaded with FC-24 (hydrocracking catalyst) and FF-66 (hydrogenation post-treatment catalyst) (the loading volume ratio of the two was 10:1); the reaction temperature of the pretreatment section of the first hydrogenation reaction zone was 376°C, the reaction pressure was 14.0 MPa, the hydrogen-to-oil volume ratio was 800:1, and the liquid hourly volume space velocity was 0.9 h -1 The reaction temperature of the cracking section is 360°C, the reaction pressure is 13.5MPa, the hydrogen-oil volume ratio is 1000:1, and the liquid hourly volume space velocity is 1.5h -1 , control> 350℃ conversion rate to 70%, the reaction effluent enters the high-pressure gas-liquid separator, its operating pressure is 13.5MPa, temperature is 95℃, and the mass ratio of hydrogen to hydrocarbons in the top gas phase is controlled to be 1.61. The liquid phase discharged from the bottom of the separator enters the separation and fractionation system for component separation. The liquid intermediate distillate oil in the middle of the fractionation system and the gas phase at the top of the separator enter the second hydrogenation reaction zone together, the reaction temperature is 322℃, the reaction pressure is 13.0MPa, the hydrogen-oil volume ratio is 1000:1, and the liquid hourly volume space velocity is 1.5h -1 , the single-pass conversion rate of the second stage>177℃ is controlled to be 65%, and the liquid phase after the reaction enters the above-mentioned separation and distillation system to obtain light hydrocarbons, light naphtha, heavy naphtha, middle distillate diesel and tail oil, among which the middle distillate oil is used as circulating oil, the heavy naphtha is used as a chemical raw material, and the tail oil is used as a raw material for steam cracking to produce ethylene.

[0052] Comparative Example 1

[0053] The raw material 1 in Table 1 was processed. The first hydrogenation reaction zone was graded from top to bottom with FF-66 hydrogenation pretreatment catalyst and FC-24 hydrocracking catalyst (the loading volume ratio of the two was 5:3), and the second hydrogenation reaction zone was loaded with FC-24 (hydrocracking catalyst) and FF-66 (hydrogenation post-treatment catalyst) (the loading volume ratio of the two was 8:1); the reaction temperature of the pretreatment section of the first hydrogenation reaction zone was 381°C, the reaction pressure was 14.0 MPa, the hydrogen-oil volume ratio was 700:1, and the liquid hourly volume space velocity was 0.9 h -1 The reaction temperature of the cracking section is 367°C, the reaction pressure is 13.5MPa, the hydrogen-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1 , control>350℃ conversion rate to 80%, the liquid components produced enter the separation and fractionation system, the liquid phase middle distillate oil and hydrogen in the middle of the fractionation enter the second hydrogenation reaction zone, the reaction temperature is 311℃, the reaction pressure is 13.0MPa, the hydrogen-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1 , the single-pass conversion rate of the second stage>177℃ is controlled to be 65%, and the liquid phase after the reaction enters the above-mentioned separation and distillation system to obtain light hydrocarbons, light naphtha, heavy naphtha, middle distillate diesel and tail oil, among which the middle distillate oil is used as circulating oil, the heavy naphtha is used as a chemical raw material, and the tail oil is used as a raw material for steam cracking to produce ethylene.

[0054] Comparative Example 2

[0055] The raw material 1 in Table 1 was processed. The first hydrogenation reaction zone was graded from top to bottom with FF-66 hydrogenation pretreatment catalyst and FC-24 hydrocracking catalyst (the loading volume ratio of the two was 5:3), and the second hydrogenation reaction zone was loaded with FC-24 (hydrocracking catalyst) and FF-66 (hydrogenation post-treatment catalyst) (the loading volume ratio of the two was 8:1); the reaction temperature of the pretreatment section of the first hydrogenation reaction zone was 381°C, the reaction pressure was 14.0 MPa, the hydrogen-oil volume ratio was 700:1, and the liquid hourly volume space velocity was 0.9 h -1 The reaction temperature of the cracking section is 367°C, the reaction pressure is 13.5MPa, the hydrogen-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1 , control> 350℃ conversion rate is 80%, the output liquid components enter the separation and fractionation system, the liquid phase middle distillate oil and hydrogen in the middle of the fractionation enter the second hydrogenation reaction zone, the second stage gas phase is sulfurized, the hydrogen sulfide concentration is controlled to be 1000μl / l, the reaction temperature is 308℃, the reaction pressure is 13.0MPa, the hydrogen-to-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1, the single-pass conversion rate of the second stage>177℃ is controlled to be 65%, and the liquid phase after the reaction enters the above-mentioned separation and distillation system to obtain light hydrocarbons, light naphtha, heavy naphtha, middle distillate diesel and tail oil, among which the middle distillate oil is used as circulating oil, the heavy naphtha is used as a chemical raw material, and the tail oil is used as a raw material for steam cracking to produce ethylene.

[0056] Comparative Example 3

[0057] The raw material 1 in Table 1 was processed. The first hydrogenation reaction zone was graded from top to bottom with FF-66 hydrogenation pretreatment catalyst and FC-24 hydrocracking catalyst (the loading volume ratio of the two was 5:3), and the second hydrogenation reaction zone was loaded with FC-24 (hydrocracking catalyst) and FF-66 (hydrogenation post-treatment catalyst) (the loading volume ratio of the two was 8:1); the reaction temperature of the pretreatment section of the first hydrogenation reaction zone was 381°C, the reaction pressure was 14.0 MPa, the hydrogen-oil volume ratio was 700:1, and the liquid hourly volume space velocity was 0.9 h -1 The reaction temperature of the cracking section is 368°C, the reaction pressure is 13.4MPa, the hydrogen-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1 , control> 350℃ conversion rate to 80%, the output liquid components enter the separation and fractionation system, the liquid phase middle distillate oil and hydrogen in the middle of the fractionation enter the second hydrogenation reaction zone, the second stage gas phase is used for sulfur and ammonia supplementation, the hydrogen sulfide concentration is controlled to be 1000μl / l, the ammonia concentration is controlled to be 500μl / l, the reaction temperature is 317℃, the reaction pressure is 12.9MPa, the hydrogen-to-oil volume ratio is 900:1, and the liquid hourly volume space velocity is 1.5h -1 The single-pass conversion rate of the second stage is controlled to be 65%, and the liquid phase after the reaction enters the above-mentioned separation and fractionation system to obtain light hydrocarbons, light naphtha, heavy naphtha, middle distillate diesel and tail oil, among which the middle distillate is used as circulating oil, the heavy naphtha is used as chemical raw material, and the tail oil is used as raw material for steam cracking to produce ethylene.

[0058] Table 1 Properties of crude oil

[0059]

[0060]

[0061] Table 2 Main physicochemical properties of the catalysts used in each example

[0062] project FF-66 FC-24 Active metal composition Mo-Ni Mo-Ni <![CDATA[MoO3,%]]> 22.2 14.9 NiO, % 4.2 5.5 Y molecular sieve content, % -- 51 Physical properties Appearance and shape Shamrock Strips Cylindrical Bar Crushing strength, N / cm ≥150 >180 Particle diameter, mm 1.0～1.4 1.5～1.7

[0063] Table 3 Main reaction conditions of each example

[0064]

[0065] Table 4 Main reaction conditions of each comparative example

[0066] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Conversion rate of the first hydrogenation reaction zone, % 80 80 80 Gas phase hydrogen / hydrocarbon mass ratio in the second hydrogenation reaction zone 1.11 1.13 1.14

[0067] Table 5 Comparison of the effects of different conditions used in each case

[0068]

[0069] Table 6 Main properties of chemical raw materials obtained in Example

[0070] project Example 1 Example 2 Example 3 Example 4 Heavy naphtha aromatic potential, % 47.6 46.4 49.8 48.1 Tail oil BMCI 12.1 11.2 13.3 12.5

[0071] As can be seen from Table 6, the heavy naphtha and tail oil obtained in the embodiments of the present invention have good properties as chemical raw materials.

Claims

1. A two-stage hydrocracking method for producing more chemical raw materials, wherein: The method comprises a first hydrogenation reaction zone and a second hydrogenation reaction zone, and the process comprises: feedstock oil and hydrogen first enter the first hydrogenation reaction zone for reaction, the one-way conversion rate of the first hydrogenation reaction zone is controlled to be 70%-85%, the effluent of the first hydrogenation reaction zone enters a high-pressure gas-liquid phase separator, the pressure controlled in the high-pressure gas-liquid phase separator is lower than the reaction pressure of the first hydrogenation reaction zone, the temperature is 80-100°C, the mass ratio of hydrogen to hydrocarbons in the gas phase components obtained at the top of the high-pressure gas-liquid phase separator is 1.20-1.70, all heavy liquid phase components obtained at the bottom of the high-pressure gas-liquid phase separator enter a separation and fractionation system to obtain light hydrocarbons, light naphtha, heavy naphtha, diesel and tail oil, the diesel obtained by fractionation and the gas phase components obtained at the top of the high-pressure gas-liquid phase separator enter the second hydrogenation reaction zone together for reaction, the one-way conversion rate of the second hydrogenation reaction zone is controlled to be 40%-80%, and the effluent of the second hydrogenation reaction zone enters the separation and fractionation system; Among them, heavy naphtha is used as a chemical raw material for catalytic reforming, and tail oil is used as a chemical raw material for steam cracking to produce ethylene; The raw material oil is selected from wax oil; The temperature point corresponding to the one-way conversion rate of the first hydrogenation reaction zone is 330°C to 370°C, and the temperature point corresponding to the one-way conversion rate of the second hydrogenation reaction zone is 175°C to 177°C; The liquid phase component obtained from the high-pressure gas-liquid phase separator and the effluent from the second hydrogenation reaction zone share a set of separation and fractionation systems.

2. The method according to claim 1, characterized in that The temperature in the high-pressure gas-liquid phase separator is controlled at 85~95°C.

3. The method according to claim 1, characterized in that In the gas phase components obtained at the top of the high-pressure gas-liquid phase separator, the mass ratio of hydrogen to hydrocarbons is 1.25~1.

65.

4. The method according to claim 1, characterized in that The single-pass conversion rate of the second hydrogenation reaction zone is controlled to be 60%~70%.

5. The method according to claim 1, characterized in that The upper part of the first hydrogenation reaction zone is a hydrogenation pretreatment section, and the lower part is a hydrocracking section; the upper part of the second hydrogenation reaction zone is a hydrocracking section, and the lower part is a hydrogenation post-treatment section.

6. The method according to claim 5, characterized in that The hydrogenation pretreatment section is filled with a hydrogenation pretreatment catalyst, and the hydrogenation posttreatment section is filled with a hydrogenation posttreatment catalyst; the hydrogenation pretreatment catalyst or the hydrogenation posttreatment catalyst, based on the weight of the catalyst, has a Group VIB metal content of 10% to 30% in terms of oxide; and a Group VIII metal content of 0.5% to 7.5% in terms of oxide.

7. The method according to claim 6, characterized in that The hydrogenation pretreatment catalyst or hydrogenation posttreatment catalyst has a Group VIB metal content of 15% to 30% in terms of oxide, and a Group VIII metal content of 1.5% to 6.5% in terms of oxide, based on the weight of the catalyst.

8. The method according to claim 5 or 6, characterized in that The hydrocracking sections in the first hydrogenation reaction zone and the second hydrogenation reaction zone are loaded with a hydrocracking catalyst; the hydrocracking catalyst has a hydrogenation active metal component content of 9% to 31% in terms of oxide and a molecular sieve content of 40% to 65% based on the weight of the catalyst.

9. The method according to claim 8, characterized in that The hydrocracking catalyst has a hydrogenation active metal component content of 14% to 26% in terms of oxide, and a molecular sieve content of 50% to 65%, based on the weight of the catalyst.

10. The method according to claim 1, characterized in that The properties of the wax oil are: the initial distillation point is 250-350°C, the final distillation point is 460-560°C, and the density at 20°C is not more than 0.93 g / cm 3 , the sulfur content by mass shall not be less than 0.2%, and the nitrogen content by mass shall not be less than 0.05%.

11. The method according to claim 10, characterized in that The properties of the wax oil are: the final distillation point is 470°C to 550°C, and the density at 20°C is not more than 0.92g / cm 3 The sulfur content by mass is 0.2%~2%, and the nitrogen content by mass is not less than 0.08%.

12. The method according to claim 10, characterized in that The properties of the wax oil are: density at 20°C is 0.87-0.92 g / cm 3 , the nitrogen mass content is 0.08%~0.2%.

13. The method according to claim 5, characterized in that The operating conditions of the hydrogenation pretreatment stage are: reaction temperature 300°C~440°C, hydrogen-oil volume ratio 500:1~1100:1, pressure 11.0MPa~17.0MPa, liquid hourly volume space velocity 0.3h -1 ~5.0h -1 .

14. The method according to claim 13, characterized in that The operating conditions of the hydrogenation pretreatment stage are: reaction temperature 320°C~410°C, hydrogen-to-oil volume ratio 600:1~1000:1, pressure 12.0MPa~16.0MPa, liquid hourly volume space velocity 0.4h -1 ~4.0h -1 .

15. The method according to claim 5, characterized in that In the first hydrogenation reaction zone, the operating conditions of the hydrocracking section are: reaction temperature 320°C~450°C, hydrogen-oil volume ratio 800:1~1500:1, pressure 10.5MPa~16.5MPa, liquid hourly volume space velocity 0.4h -1 ~4.5h -1 .

16. The method according to claim 15, characterized in that In the first hydrogenation reaction zone, the operating conditions of the hydrocracking section are: reaction temperature 330°C~400°C, hydrogen oil volume ratio 900:1~1400:1, pressure 11.0MPa~16.0MPa, liquid hourly volume space velocity 0.5h -1 ~4.0h -1 .

17. The method according to claim 5 or 15, characterized in that In the second hydrogenation reaction zone, the loading volume ratio of the hydrocracking catalyst to the hydrogenation post-treatment catalyst is 7-13, and the operating conditions of the second hydrogenation reaction zone are: reaction temperature 260°C-380°C, hydrogen-oil volume ratio 700:1-1400:1, pressure 9.5MPa-15.5MPa, liquid hourly volume space velocity 0.5h -1 ~5.0h -1 .

18. The method according to claim 17, characterized in that In the second hydrogenation reaction zone, the loading volume ratio of the hydrocracking catalyst to the hydrogenation post-treatment catalyst is 8-12, and the operating conditions of the second hydrogenation reaction zone are: reaction temperature 280°C-360°C, hydrogen-oil volume ratio 800:1-1300:1, and pressure 10.0MPa-15.0MPa.

19. The method according to claim 1, characterized in that The temperature point corresponding to the single-pass conversion rate of the first hydrogenation reaction zone is 340°C~360°C.

20. The method according to claim 1, 2 or 3, characterized in that: The pressure of the high-pressure gas-liquid phase separator is 10.0 MPa to 16.0 MPa.

21. The method according to claim 20, characterized in that The pressure of the high-pressure gas-liquid phase separator is 10.5MPa~15.5MPa.

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