A method for producing light olefins and aromatics by catalytic cracking of crude oil

Abstract

This invention belongs to the field of crude oil catalytic conversion technology, and specifically relates to a method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil. Through the integrated design of crude oil separation and catalytic cracking, the two components of crude oil are separated by utilizing the heat of catalytic cracking products. The light and heavy components of crude oil are catalytically cracked in their respective cracking reactors under the required conditions. The light components of crude oil are directly catalytically cracked in the gas phase, thereby realizing the catalytic cracking of all components of crude oil to produce ethylene and propylene.

Description

Technical Field

[0001] This invention belongs to the field of crude oil catalytic conversion technology, and specifically relates to a method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil. Background Technology

[0002] Low-carbon olefins, represented by ethylene and propylene, are the most basic raw materials in the chemical industry. Current catalytic conversion technologies produce low-carbon olefins as a byproduct of gasoline and diesel production, which is far from meeting the current market demand for organic chemical raw materials. Aromatics are an important organic chemical raw material, second only to ethylene and propylene in terms of production volume and scale. Their derivatives are widely used in the production of chemical fibers, plastics, rubber, and other chemical products and fine chemicals. With the continuous development of the petrochemical and textile industries, the global demand for aromatics is also constantly increasing. Domestically and internationally, low-carbon olefins are mostly produced using natural gas or light petroleum distillates as raw materials, employing steam cracking processes in ethylene complexes. This process produces large quantities of other olefins and aromatics as byproducts of ethylene production. Although steam cracking technology has been developed and improved over decades, it still suffers from limitations such as high energy consumption, high production costs, large CO2 emissions, and difficulty in adjusting product structure. Traditional steam cracking technologies for producing ethylene and propylene are facing severe challenges. Utilizing catalytic conversion methods to produce low-carbon olefins, while simultaneously producing byproducts such as propylene, butene, and aromatics, represents a new direction for solving resource shortages and achieving low-cost production of chemical products, and has become an important research topic and hot issue.

[0003] The common approach in refineries is to first separate crude oil into different components under atmospheric or vacuum pressure, and then process these components separately. Existing technologies primarily focus on processing these fractionated components. Regarding the catalytic conversion to produce low-carbon olefins, with byproducts such as propylene and butene, the main approaches are as follows:

[0004] 1. Different components undergo catalytic reactions in separate reactors. For example, CN109575982A provides a method for catalytic cracking of crude oil to produce low-carbon olefins and aromatics. After desalting and dehydration, the crude oil is heated in a furnace and then fed into a distillation column, where it is separated into light, high-boiling-point components with cut-off points between 150 and 300°C. The low-boiling-point components from the top of the column and the high-boiling-point components from the bottom of the column react with a high-temperature catalyst in a steam atmosphere in two separate reactors. In fact, almost all catalytic cracking feedstocks are produced in this way. All catalytic cracking feedstocks come from atmospheric and vacuum distillation, only undergoing intermediate processes such as heating furnaces, fractionation, cooling, liquefaction, and storage.

[0005] A Saudi Arabian company invented a method for producing chemicals by catalytic cracking of light and heavy components of crude oil in separate downflow reactors, as described in CN104903427.

[0006] 2. Layered feed reaction within the reactor. For example, CN1898362 provides a method for producing low-carbon olefins and aromatics. The feedstock contacts a catalytic cracking catalyst, and the reaction is carried out in at least two layers depending on the properties of the feedstock. In addition to the target product, different liquid reaction products from the fractionation tower are returned to the reactor for further conversion from different locations. CN1215041A provides a method for the direct conversion of multiple feed hydrocarbons to produce olefins, including low-carbon olefins, propylene, and aromatics. The reactor is equipped with multiple feed ports, allowing hydrocarbons with different properties to enter the unit from different feed ports and undergo cracking reactions under the same process conditions in each section. CN104560154A provides a method for catalytic conversion of hydrocarbons to produce high yields of low-carbon olefins and light aromatics. The method includes: contacting a heavy hydrocarbon feedstock with a cracking catalyst in a reaction zone for catalytic cracking, then separating a first coking catalyst and a first reaction product; injecting a light hydrocarbon feedstock upstream of a second reactor and a medium hydrocarbon feedstock from the middle of the second reactor for catalytic cracking; introducing the reaction mixture generated in the second reactor into a third reactor for further reaction, then separating a second coking catalyst and a second reaction product. The cracking catalyst is a cracking catalyst containing modified β-zeolite, wherein the modified β-zeolite is β-zeolite modified with linylene and transition metal M.

[0007] 3. In addition to the feedstock riser, a separate reactor is built to catalytically convert different fractions again. That is, a multi-reactor form is adopted. The conventional feedstock reaction is carried out in the reaction zone. After fractionation, one or more fractions, such as crude gasoline, enter the separate reactor for further conversion to obtain the target product. For example, CN1388216 discloses a catalytic conversion method for producing propylene, butene and low-olefin gasoline, including the following steps: (1) The preheated hydrocarbon oil (still liquid) is injected into the riser and reacts with the catalyst containing five-membered ring high-silica zeolite and Y-type zeolite. The oil-catalyst mixture enters the fluidized bed through the riser; (2) The gasoline is injected into the fluidized bed and reacts with the catalyst from the riser; (3) The oil-catalyst mixture is separated. The catalyst after reaction is stripped and sent to the regenerator for regeneration. The regenerated catalyst is returned to the riser for recycling. This method can increase the production of low-carbon olefins and produce high-quality gasoline with low olefin content. CN1258580C discloses a method and system for deep olefin reduction and octane number enhancement of catalytic converter gasoline. This method involves adding a catalytic reforming reactor to the reaction-regeneration system of a heavy oil catalytic converter to perform catalytic reforming reactions on catalytic converter gasoline fractions. The reformed catalytic converter gasoline fractions can be crude gasoline full fraction, crude gasoline light fraction, or crude gasoline heavy fraction, obtained by establishing a two-stage condensation system at the top of the fractionation tower.

[0008] Crude oil distillation and fractionation are common and well-known processes; catalytic cracking or catalytic pyrolysis feedstocks mainly come from crude oil fractionation units, such as atmospheric heavy oil from atmospheric distillation, wax oil from vacuum distillation, and naphtha from atmospheric distillation in catalytic pyrolysis. Although the feedstocks for catalytic pyrolysis units mainly come from crude oil distillation, existing catalytic cracking or pyrolysis technologies are basically focused on how to improve the catalytic pyrolysis effect; they have not addressed how to directly combine crude oil and catalytic pyrolysis.

[0009] Many existing technologies or patents describe the separation of crude oil into heavy and light components for separate catalytic cracking, but they fail to address how to connect these components with catalytic cracking, let alone how to shorten the process, reduce investment, lower energy consumption, or reduce carbon emissions. Conventional crude oil distillation is a mature and widely used technology, but existing crude oil distillation technologies cannot be combined with catalytic cracking. They can only cool and liquefy the separated products, pump them to the tank farm, and then pressurize them for catalytic cracking. How to achieve the pressurized separation of crude oil required for combined crude oil distillation and catalytic cracking, and how to adjust the separation ratio and accuracy without setting up a side-stream heat exchange system, are problems that must be solved in crude oil catalytic cracking.

[0010] In fact, this kind of description of existing technology applies to all existing catalytic cracking units. All catalytic cracking, and even all secondary processing units, such as hydrocracking, use crude oil fractionation units as feedstock. It can all be described as "crude oil fractionation followed by entry into a certain unit." This is the basic process of oil refining and does not involve technical measures or implementation plans. Patents are a technical aspect; specific technical measures are the core of technological progress.

[0011] Existing crude oil fractionation is achieved under low or even negative pressure, at atmospheric or even reduced pressure (negative pressure). However, catalytic cracking units are pressurized. When crude oil distillation is directly coupled with catalytic cracking or pyrolysis units, the crude oil separation pressure must be higher than the catalytic cracking reaction pressure. Although this can be described in a general way as "crude oil is separated into different components and then subjected to catalytic cracking," it clearly does not involve specific technical solutions. Existing distillation technology cannot be directly used for crude oil separation and catalytic cracking. In addition, existing crude oil fractionation processes achieve crude oil separation through side-stream heat extraction and cooling to achieve cold reflux. Crude oil distillation towers require external heating furnaces and a large number of heat exchange equipment, resulting in complex processes, large investments, high energy consumption, and high carbon emissions.

[0012] Existing industrial flash distillation towers can achieve partial component separation without side-stream heat exchange. However, due to the lack of side-stream heat exchange and other reasons, existing flash distillation towers can only separate a small amount of gas and light naphtha components from crude oil, and this needs to be done at atmospheric pressure. The component separation accuracy is low, and the separated components generally re-enter the distillation tower. In particular, it is impossible to arbitrarily adjust the light and heavy components of crude oil, and it is even more impossible to operate in conjunction with catalytic cracking units.

[0013] ExxonMobil innovatively combined crude oil fractionation and steam cracking in its design. Utilizing the heat from the convection section of a steam cracking furnace to heat the crude oil, the naphtha components are separated and directly subjected to steam cracking, thus opening up a new field of "direct crude oil to olefins or chemicals" worldwide. This approach became a landmark milestone in the direct crude oil to chemical production technology. Essentially, this technology combines crude oil fractionation and steam cracking; each component is already used in refineries and does not involve new theories or principles. However, the combined design significantly shortens outflow, reduces investment and energy consumption, and improves economic efficiency. Economic efficiency is a core advancement in chemical technology. Summary of the Invention

[0014] Purpose of the Invention: In any field, being "usable" or "roughly" simple is challenging, but improving efficiency is difficult. Technological advancements address the problem of improving efficiency. Catalytic cracking for ethylene production often suffers from insufficient heat in the cracking reaction phase and the difficulty in utilizing the large amount of heat in the cracking product gases. This invention aims to provide a method with high heat utilization efficiency, achieving low-investment, low-energy-consumption pressurized two-component distillation separation of crude oil, while simultaneously allowing the different components after crude oil separation to undergo independent selective catalytic cracking, crude oil separation, and catalytic cracking thermal co-transport under required conditions. This simplifies and shortens the process, reducing investment and energy consumption.

[0015] Specifically, this invention provides a method for producing low-carbon olefins and aromatics through catalytic cracking of crude oil. This method achieves two-component distillation separation of crude oil and direct selective catalytic cracking of these components to produce low-carbon olefins and aromatics within a single integrated unit. The technical solution is as follows: The heat from the catalytic cracking products is used to distill and separate crude oil into two components for catalytic cracking, achieving direct thermal coupling and integrated operation of crude oil separation and catalytic cracking. In the separation tower, crude oil is countercurrently mixed with a portion of the catalytic cracking product gas, resulting in the vaporization of the component with the lower actual boiling point. The crude oil and the catalytic cracking product gas entering the separation tower form a mixed component consisting of a light component with a lower actual boiling point and a heavy component with a higher actual boiling point. The light component, or light component mixture (actually a mixture, including not only components from the crude oil but also components from the stream entering the separation tower), and the heavy component, or heavy component mixture, undergo catalytic cracking. The process is as follows:

[0016] (1) Using catalytic cracking reaction products as the heat source for crude oil separation, some of the catalytic cracking product gas enters the separation tower from the bottom and flows upward, providing the heat required for crude oil distillation or the vaporization of components with low true boiling points. Crude oil enters the separation tower above the catalytic cracking product gas. Specifically, liquid crude oil enters the separation tower from above the crude oil inlet or from the top of the separation tower. The crude oil descends due to gravity within the separation tower and mixes with the rising gas stream. The crude oil comes into contact with the catalytic cracking product gas or the upward-flowing gas, and is heated by the catalytic cracking product gas or the upward-flowing gas to achieve the vaporization of components with low true boiling points. The liquid component with a high actual boiling point flows downward and contacts the catalytic cracking product gas or the upward-flowing gas; at the same time, the catalytic cracking product gas or the upward-flowing gas is cooled down, in which the heavy components or components with a high actual boiling point are liquefied. The liquefied components with a high actual boiling point in the catalytic cracking product gas or the upward-flowing gas mix with the unvaporized liquid components with a high actual boiling point in the crude oil and flow downward, forming heavy components that flow out from the bottom of the separation tower. The light components or components with a low actual boiling point in the catalytic cracking product gas mix with the components with a low actual boiling point in the crude oil and the steam to form light components that flow upward out of the separation tower, that is, out from the top of the separation tower.

[0017] (2) The high-boiling-point liquid phase component, i.e. the heavy component, flowing out from the bottom of the separation tower is pressurized and transported to the catalytic cracking reactor by a pump. After being atomized by steam, it enters the fluidized catalytic cracking reactor for catalytic cracking reaction. The low-boiling-point gas phase component, i.e. the light component, separated from the separation tower is directly or after being heated to a higher temperature and then transported into the fluidized catalytic cracking reactor for fluidized catalytic cracking, thereby reducing the heat required for the catalytic cracking reaction.

[0018] In specific implementation, the heating temperature of the light component shall not exceed 600°C; the heating temperature of the heavy component shall not exceed 380°C, preferably not exceed 350°C.

[0019] (3) The catalyst from the regenerator enters the catalytic cracking reactor, and after the reaction, it flows out of the reactor together with the catalytic cracking reaction products to realize the catalytic cracking reaction of crude oil; the regenerator is well known to technicians.

[0020] (4) The catalyst is separated from the product after the catalytic cracking reaction in the reactor. The catalyst is stripped and returned to the regenerator for regeneration and reuse. The reaction product after catalyst separation flows out from the settling tank and enters the subsequent product separation section. The settling tank and stripping tank are well known to the technicians.

[0021] In specific implementation, the catalytic cracking reaction pressure is 90 kPa (gauge pressure) to 200 kPa (gauge pressure), and the top pressure of the separation tower is 100 kPa (gauge pressure) to 200 kPa (gauge pressure).

[0022] In the above-mentioned method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil, the crude oil further enters the separation tower from the top of the separation tower;

[0023] Alternatively, crude oil can be introduced into the separation tower in stratified layers at different heights. Through this stratified distribution, crude oil is supplied to the separation tower in stratified layers, achieving stratified cooling of the rising gas stream within the tower. This achieves the same effect as the reflux of heat extracted via a side stream in a conventional distillation tower, ultimately realizing temperature control within the separation tower and the separation of the two components of the crude oil. Alternatively, crude oil can be introduced into the separation tower in stratified layers after being heated to different temperatures. Specifically, the crude oil introduced into the separation tower in stratified layers can be heated by a heat exchanger before being introduced into the separation tower in stratified layers, or the crude oil introduced in stratified layers can be heat-exchanged separately and then introduced into the separation tower in stratified layers at different temperatures, with the higher-temperature crude oil entering at the lower layer.

[0024] The above-mentioned method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil is further improved by introducing a liquid stream above the crude oil inlet or at the top of the separation tower. The liquid stream enters the separation tower either once or in layers, further reducing the proportion of heavy components or high-boiling-point components (i.e., components with high actual boiling points) in the light components or low-actual-boiling-point light component mixture that flows out of the separation tower from the top.

[0025] In specific implementation, the liquid stream is a liquid with more than 90% of its components having a true boiling point below 360°C, preferably hydrocarbons with more than 90% of their components having a true boiling point below 360°C; further, the liquid stream is a gasoline component, diesel, or a mixture of gasoline and diesel or LCO component, or the liquid stream is a gasoline, LCO, or a mixture of gasoline and LCO from a catalytic cracking reaction product fractionation tower; LCO is light cycle oil;

[0026] Furthermore, the temperature of the liquid stream is not greater than 250°C, preferably not greater than 150°C;

[0027] The liquid stream enters the separation tower in stratified layers at different locations.

[0028] To improve crude oil separation accuracy and reduce component overlap, trays are installed within the separation tower; these trays are familiar to technicians. In practice, trays are preferably placed below the crude oil inlet, or simultaneously below and above the crude oil inlet, or below both the liquid stream inlet and the crude oil inlet. Further to reduce pressure drop and energy consumption, and improve separation efficiency, no more than six trays are placed above and / or above each crude oil inlet. In practice, the crude oil and liquid streams are distributed into the separation tower via a liquid distributor; this liquid distributor is familiar to technicians.

[0029] The above-mentioned method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil is further improved by setting up two reactors, wherein the heavy components and the light components are respectively subjected to catalytic cracking reactions in independent reactors; the light components separated from the separation tower are directly introduced into the gas phase or reheated and then introduced into the gas phase into the second reactor for catalytic cracking reactions; the heavy components separated from the bottom of the separation tower are atomized by steam and then introduced into the first reactor for catalytic cracking reactions.

[0030] The above-mentioned method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil is further described in the following way: after the catalyst is separated from the reaction product of the catalytic cracking of the first reactor, i.e. the heavy component catalytic cracking product, the gas phase of which is directly or after heat exchange continues to enter the second reactor for further catalytic cracking; specifically, after the catalyst is separated from the heavy component catalytic cracking product, it continues to enter the second reactor, i.e. the light component reactor, for cracking.

[0031] Furthermore, after the catalyst is separated from the reaction product of the catalytic cracking of the first reactor, namely the heavy component catalytic cracking product, it continues to enter the second reactor downstream of the light component inlet (i.e. above the inlet) or after the light component undergoes a cracking reaction of 0.2 seconds to 1.5 seconds, for further catalytic cracking.

[0032] Alternatively, after the catalyst is separated from the catalytic cracking products of the heavy components, they can continue to enter the second reactor upstream (i.e. below the inlet) or before the reaction of the light components for further catalytic cracking. Specifically, the catalytic cracking products of the heavy components are reacted first in the second reactor, and then the light components are reacted.

[0033] In the above-mentioned method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil, the first and second reactors are in an "upward" configuration, with the catalyst and reactants entering the reactor from the bottom and flowing upward, and exiting the reactor after the reaction is completed; the heavy components and light components react in the upward reactor or upward reaction zone, with the catalyst and reactants entering the reactor or reaction zone from the bottom, and the reactants or products flowing out of the reactor from the top, carrying the catalyst.

[0034] Alternatively, the first and second reactors are in a downward configuration, with the catalyst and reactants entering the reactor from above and exiting from the bottom; the heavy and light components react in the downward reactor or downward reaction zone, with the catalyst and reactants entering the reactor or reaction zone from above, and the reactants or products carrying the catalyst exiting the reactor from below or the bottom.

[0035] Alternatively, in the first and second reactors, one reactor is in a downward configuration, where the catalyst and reactants enter from the top and exit from the bottom; the other reactor is in an upward configuration, where the catalyst and reactants enter from the bottom and exit from the top. Specifically, one of the heavy and light components reacts in the upward reactor, where the catalyst and reactants enter from the bottom, and the reactants or products, along with the catalyst, exit from the top; the other component reacts in the downward reactor, where the catalyst and reactants enter from the top, and the reactants or products, along with the catalyst, exit from the bottom.

[0036] The catalytic cracking temperature of the light component or the second reactor is 580°C to 700°C, and the catalytic cracking reaction temperature of the heavy component or the first reactor is 550°C to 670°C.

[0037] Furthermore, when the first and second reactors are in an "upward" configuration, the first reactor preferably employs pneumatic conveying fluidization, or a reaction mode combining pneumatic conveying fluidization with a fast fluidized bed or turbulent fluidized bed in series, wherein the fast fluidized bed or turbulent fluidized bed is located in the middle or upper part of the reactor. Specifically, when the heavy component mixture reacts in the upward reactor, i.e., when the first reactor adopts an upward reaction configuration, the first reactor can employ a "lift pipe" or pneumatic conveying fluidization, or a reaction mode combining pneumatic conveying with a fast fluidized bed or turbulent fluidized bed in series, wherein the fast fluidized bed or turbulent fluidized bed is located in the middle of the reactor; preferably, the catalyst weight hourly space velocity in the fast fluidized bed or turbulent fluidized bed reaction zone is 3 (1 / h) to 20 (1 / h).

[0038] In specific implementation of this invention:

[0039] Injecting steam into the reactor reduces the partial pressure of hydrocarbons (either the first or second reactor can be used) and increases the yield of low-carbon olefins, especially propylene. Specifically, reducing the partial pressure is beneficial for increasing propylene yield. Injecting steam into the first reactor is highly efficient because, firstly, the molecular weight of heavy components is large, and the effect of steam injection is obvious; secondly, the steam injected into the first reactor will continue to enter the second reactor. The amount of steam injected should be controlled so that the total steam in the reactor does not exceed 60% (by mass) of the reaction feedstock.

[0040] Furthermore, non-propylene, non-ethylene, and non-light aromatic components, such as gasoline components, LCO components, C5 components, C4 components, propane, and ethane components, are separated from the reaction products by the subsequent catalytic cracking product separation system and returned to the reactor for further reprocessing and cracking. The reprocessed components are returned to the second reactor or simultaneously partially returned to the first reactor for cracking and partially returned to the second reactor for cracking. Components with C5 and fewer carbon numbers are cracked at the bottom of the reactor during the reprocessing process.

[0041] Hydrocarbons with C5 and fewer carbon atoms are cracked at the bottom of the reactor using riser, rapid fluidized bed, or turbulent fluidized bed methods; reprocessing of C4 and other hydrocarbons is a common technique; C5 hydrocarbons have 5 carbon atoms, and C4 hydrocarbons have 4 carbon atoms.

[0042] The "lift pipe", pneumatic conveying, rapid fluidized bed, and turbulent fluidized bed mentioned above are familiar to those skilled in the art;

[0043] In this invention, when reprocessing is required, for example, when non-target chemical products in the product of this invention are reprocessed or petroleum hydrocarbons in other devices are cracked in the reactor of this invention, light hydrocarbons with a true boiling point below 360°C or more are preferentially catalytically cracked in the second reactor; and streams with a true boiling point above 300°C or more are preferentially catalytically cracked in the first reactor.

[0044] Beneficial effects:

[0045] In the process of high-temperature catalytic cracking to produce low-carbon olefins, the reaction requires a large amount of heat, and the regeneration of the reaction coke generally cannot provide the heat required for the reaction, often requiring supplemental heating. However, the cracking product gas contains excess heat. Balancing the heat required for the reaction and the excess heat of the reaction products is beneficial to improving economic efficiency. Crude oil has a wide range of components, and naphtha and heavy components require significantly different cracking conditions. Separating the light and heavy components of crude oil and then selectively cracking them separately is beneficial to improving cracking efficiency. This invention effectively solves the relationship between crude oil separation and selective catalytic cracking of different components, reduces the investment and energy consumption of crude oil separation, reduces the heat required for catalytic cracking, and has good economic benefits. Attached Figure Description

[0046] The accompanying drawings are merely illustrative of embodiments of the present invention, and the specific implementation is not limited to these.

[0047] Figure 1 This is a process diagram of Embodiment 1 of the present invention;

[0048] Figure 2 This is a schematic diagram of the process in Embodiment 2 of the present invention;

[0049] Figure 3 This is a schematic diagram of an embodiment.

[0050] The numbering labels in the diagram are as follows: 10 First reactor or heavy component reactor, 20 Second reactor or light component reactor, 30 First settling stripper, 30A Second settling stripper, 40 Separation tower (or flash tower).

[0051] 11 First steam, 21 Second steam; 12 First catalyst valve, 22 Second catalyst valve; 12A First reactor catalyst inlet, 22A Second reactor catalyst inlet; 13 First catalyst delivery pipeline, 23 Second catalyst delivery pipeline; 16 First reaction feedstock, 26 Second reaction feedstock; 25 Steam; 27 (Second reactor) Rapid fluidized bed or turbulent fluidized bed reaction zone; 35 First catalyst stripping section, 35A Second catalyst stripping section; 38 First awaiting catalyst delivery pipe, 38A Second awaiting catalyst delivery pipe;

[0052] F0 Crude oil; F1 (top of the separator) liquid stream; F01 Catalytic cracking product gas (catalytic cracking product entering the separator); F02 Bottom stream of the separator or heavy component or mixture of heavy components; F03 Top stream of the separator or light component or mixture of light components; F06 Heavy component catalytic cracking product or reaction product flowing out of the first settling stripper; F06B Separation of heavy component catalytic cracking product (sent out of the reaction system or for further reaction); F07 Second reactor cracking reaction product or light component cracking reaction product; FC catalyst; FRC flow signal. Detailed Implementation

[0053] The technical solution of the present invention will be described below with specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0054] The specific implementation process is as follows:

[0055] Implementation Method 1:

[0056] like Figure 1 The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil, as shown, involves two catalytic cracking reaction systems or reactors: a first reactor 10 and a second reactor 20. Crude oil F0, after desalting and dehydration treatment, at a temperature of 110°C to 160°C, is pressurized by a pump and enters separation tower 40 as a reflux stream. A portion of the reaction product of the heavy component F02 from the bottom of the separation tower, i.e., the heavy component catalytic cracking product F06, enters separation tower 40 as catalytic cracking product gas F01. Crude oil F0 enters separation tower 40 above catalytic cracking product gas F01. Liquid stream F1, with a temperature below 250°C, enters separation tower 40 from the top. Crude oil F0 and catalytic cracking product gas F01 entering separation tower 40 are mixed and separated by mass transfer into light component F03 and heavy component F02.

[0057] Next to the separation tower 40, a first reactor 10 for the cracking of heavy component F02 and a second reactor 20 for the cracking of light component F03 are set up. Both the first reactor 10 and the second reactor 20 are in a downward configuration. The light component F03 separated from the top of the separation tower is atomized with steam 25 and directly enters the light component reactor, i.e., the second reactor 20, as the second reaction feedstock 26. The light component cracking reaction product F07 is separated from the catalyst and flows out of the second reactor 20. The heavy component F02 flowing out from the bottom of the separation tower is atomized with steam and enters the heavy component reactor, i.e., the first reactor 10, for catalytic cracking. First steam 11 is introduced into the first reactor 10 and second steam 21 is introduced into the second reactor 20 to achieve fluidization within the reactor.

[0058] After the catalyst is separated from the heavy component catalytic cracking product F06, part of it flows out of the first reactor 10 as the separated heavy component catalytic cracking product F06B and is sent out of the reaction system, while part of it enters the separation tower 40 as the catalytic cracking product gas F01 to provide a heat source for crude oil separation. In specific implementation, the catalytic cracking product gas F01 can also come from the light component cracking reaction product F07. The temperature of crude oil F0 is 100℃ to 250℃, the reaction pressure of the first reactor 10 is 120 kPa to 200 kPa, the reaction pressure of the second reactor 20 is 90 kPa (gauge pressure) to 160 kPa (gauge pressure), and the top pressure of the separation tower is 120 kPa (gauge pressure) to 180 kPa (gauge pressure).

[0059] Implementation Method Two:

[0060] like Figure 2 The method shown is for the catalytic cracking of crude oil to produce low-carbon olefins and aromatics.

[0061] In the first reactor 10, after the catalyst is separated from the heavy component catalytic cracking product F06, part of it enters the separation tower 40 as the catalytic cracking product gas F01, and part of it continues to enter the second reactor 20 as the separated heavy component catalytic cracking product F06B to continue the reaction and further catalytic cracking.

[0062] The reaction pressure of the first reactor 10 is 130 kPa (gauge pressure) to 180 kPa (gauge pressure), the top pressure of the separation tower 40 is 5 kPa to 15 kPa lower than the reaction pressure of the first reactor 10, and the reaction pressure of the second reactor 20 is 30 kPa to 45 kPa lower than the reaction pressure of the first reactor 10.

[0063] The rest is the same as in Implementation Method 1.

[0064] Example:

[0065] like Figure 3 The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil shown in the diagram has both the first reactor 10 and the second reactor 20 being in an upward configuration.

[0066] The first reactor 10 adopts a riser reaction form, and the second reactor 20 adopts a fast fluidized bed or turbulent fluidized bed reaction zone 27 and a riser in series, with the fast fluidized bed or turbulent fluidized bed reaction zone 27 below.

[0067] The first reactor catalyst inlet 12A at the bottom of the first reactor 10 is connected to the first catalyst delivery pipe 38 of the first catalyst stripping section 35 via the first catalyst delivery pipeline 13. The outlet of the first reactor 10 is connected to the gas-solid separator in the first settling stripper 30. The first catalyst valve 12 is provided on the first reactor catalyst inlet 12A.

[0068] The catalyst inlet 22A of the second reactor 20, located below the rapid fluidized bed or turbulent fluidized bed reaction zone 27, is connected to the second catalyst delivery pipe 38A of the second catalyst stripping section 35A via the second catalyst delivery pipeline 23. The outlet of the second reactor 20 is connected to the gas-solid separator in the second settling stripper 30A. A second catalyst valve 22 is provided on the catalyst inlet 22A of the second reactor.

[0069] The heavy component F02 flowing out from the bottom of the separation tower is atomized with steam and then enters the first reactor 10 as the first reaction feedstock 16 for catalytic cracking.

[0070] The structure of other parts is the same as in Implementation Method 1;

[0071] use Figure 3 The reaction system shown uses crude oil to produce low-carbon olefins via catalytic conversion;

[0072] Crude oil F0 properties: density 0.85, hydrogen content 13.0, K value 12.5, Ni content less than 3.0 ppm, V content 0.3 ppm;

[0073] Crude oil separation conditions: Crude oil F0 temperature 125℃; Liquid stream F1 is a 40℃ gasoline component from the catalytic cracking product fractionation tower, and the flow rate of liquid stream F1 is 5% of that of crude oil F0; Separation tower 40 has 3 trays below and above the crude oil inlet; Separation tower 40 pressure 155kpa (gauge pressure), top temperature 270℃, bottom temperature 350℃;

[0074] Reaction conditions:

[0075] The first reactor 10 adopts a riser reaction mode. The first settling stripper 30 operates at a pressure of 165 kPa, the separation tower 40 operates at a pressure of 155 kPa (gauge pressure), the reaction temperature of the first reactor 10 is 620℃, the reaction time is 1.8 seconds, and the steam ratio of the first reactor 10 is 35% of the amount of heavy component FO2. The second settling stripper 30A operates at a pressure of 115 kPa (gauge pressure). The main reaction zone of the second reactor 20, namely the rapid fluidized bed or turbulent fluidized bed reaction zone 27, adopts the rapid fluidized bed mode, the gas velocity is 1.5 m / s, the reaction time is 2.0 seconds, the reaction temperature is 650℃, and the steam ratio is 40%.

[0076] Regenerator (not shown in the figure): Regeneration temperature controlled at 720°C. Table 1 shows the predicted single-pass conversion gas product distribution of the example.

[0077] Table 1 Distribution of single-pass conversion gas products in the example.

[0078] Components Unit: % (weight) dry air 20 methane 3.0 ethylene 13.6 Liquefied gas 43 propylene 21.6

Claims

1. A method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil, characterized in that, The heat from the catalytic cracking product gas (F01) is used to distill and separate crude oil (F0) into two components for catalytic cracking, achieving direct thermal coupling and integrated operation of crude oil (F0) separation and catalytic cracking. In the separation tower, crude oil (F0) is mixed with a portion of the catalytic cracking product gas (F01) in a countercurrent flow, resulting in the vaporization of the component with the lower actual boiling point. This vaporizes the component with the catalytic cracking product gas entering the separation tower, forming a mixed component consisting of a light component with a lower actual boiling point and a heavy component with a higher actual boiling point. The light and heavy components then undergo catalytic cracking. The process is as follows: (1) Part of the catalytic cracking product gas (F01) enters the separation tower (40) and flows upward, providing the heat required for crude oil distillation or the vaporization of components with low actual boiling points. Crude oil (F0) enters the separation tower (40) above the catalytic cracking product gas (F01). Crude oil (F0) mixes and contacts with the catalytic cracking product gas (F01) or the upward-flowing gas. Crude oil (F0) is heated by the catalytic cracking product gas (F01) to achieve the vaporization of components with low actual boiling points. Components with high actual boiling points in the crude oil flow downward and react with the catalytic cracking product gas. The catalytic cracking product gas (F01) is in contact with the crude oil; at the same time, the catalytic cracking product gas (F01) is cooled, the high-boiling-point component in the catalytic cracking product gas is liquefied, the liquefied component of the catalytic cracking product gas (F01) and the high-boiling-point component in the crude oil (F0) mix and flow downwards, forming a heavy component (F02) which flows out from the bottom of the separation tower, and the low-boiling-point component in the catalytic cracking product gas (F01) and the low-boiling-point component in the crude oil (F0) mix with the steam to form a light component (F03) which flows upwards out of the separation tower (40). (2) The heavy component (FO2) flowing out from the bottom of the separation tower is transported to the catalytic cracking reactor, atomized by steam and then enters the catalytic cracking reactor for catalytic cracking reaction; the light component (FO3) enters the catalytic cracking reactor directly or after reheating in the gas phase for fluidized catalytic cracking. (3) The catalyst (FC) from the regenerator enters the catalytic cracking reactor, and after the reaction, it flows out of the reactor together with the reaction products to realize the catalytic cracking reaction of crude oil; (4) The catalyst (FC) is separated from the product after the reaction in the reactor. The catalyst (FC) is stripped and returned to the regenerator for regeneration and recycling. The reaction product after separating the catalyst (FC) flows out from the settling tank.

2. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 1, characterized in that: The crude oil (F0) enters the separation tower (40) from the top of the separation tower. Alternatively, the crude oil (F0) may enter the separation tower (40) in layers at different locations, and the temperature inside the separation tower (40) may be controlled by the layered distribution of the crude oil (F0); or, the crude oil (F0) may enter the separation tower (40) in layers after being heated to different temperatures.

3. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 1, characterized in that: A liquid stream (F1) enters above the crude oil (F0) or at the top of the separation tower (40), and the liquid stream (F1) enters the separation tower (40) either once or in layers, further reducing the high-boiling-point components in the light components (F03) flowing out of the separation tower (40) from the top.

4. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 1, characterized in that: Two reactors are set up. The light component (F03) separated from the separation tower (40) is directly gas-phase or reheated and then gas-phased into the second reactor (20) for catalytic cracking. The heavy component (F02) separated from the bottom of the separation tower (40) is atomized by steam and then enters the first reactor (10) for catalytic cracking reaction to obtain the heavy component catalytic cracking product (F06).

5. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 4, characterized in that: After the catalyst is separated from the catalytic cracking product (F06) of the heavy component, it continues to enter the second reactor (20) directly or after heat exchange in the gas phase for further catalytic cracking.

6. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 5, characterized in that: After the catalyst is separated from the heavy component catalytic cracking product (F06), it continues to enter the second reactor (20) downstream of the light component inlet or after the light component (F03) reaction for further catalytic cracking; Alternatively, after the catalyst is separated from the heavy component catalytic cracking product (F06), it continues to enter the second reactor (20) upstream of the light component inlet or before the light component (F03) reacts for further catalytic cracking.

7. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 4, characterized in that: The first reactor (10) and the second reactor (20) are in an upward form. The catalyst and reactants enter the reactor from the bottom and flow upward. After the reaction is completed, they flow out of the reactor. Alternatively, the first reactor (10) and the second reactor (20) are in a downward configuration, with the catalyst and reactants entering the reactor from above and exiting from the bottom.

8. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 4, characterized in that: The first reactor (10) and the second reactor (20) are of different configurations. One reactor is in a downward configuration, where the catalyst and reactants enter the reactor from the top and exit the reactor from the bottom. The other reactor is in an upward configuration, where the catalyst and reactants enter the reactor from the bottom and exit the reactor from the top.

9. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 7 or 8, characterized in that: When the first reactor (10) is in an upward form, the first reactor (10) is a pneumatic conveying fluidized bed, or a reaction mode in which pneumatic conveying fluidized bed and fast fluidized bed or turbulent fluidized bed are connected in series, wherein the fast fluidized bed or turbulent fluidized bed is in the middle or upper part of the reactor.

10. The method for producing low-carbon olefins and aromatics by catalytic cracking of crude oil as described in claim 1 or 3, characterized in that: Inside the separation tower (40), a tray is set below the crude oil inlet, or a tray is set both below and above the crude oil inlet, or a tray is set below the liquid stream inlet and below the crude oil inlet.

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