Method and apparatus for catalytic cracking of hydrocarbon feedstock oil to produce low-carbon olefins and BTX

Abstract

A method and apparatus for producing low-carbon olefins and BTX by catalytic cracking of hydrocarbon-containing feedstock oil. The method includes: cutting the hydrocarbon-containing feedstock oil into light distillate oil and heavy distillate oil; introducing the light distillate oil and a first catalyst stream into a downflow reactor for catalytic cracking to obtain a first catalytic cracked product; performing gas-solid separation on the first catalytic cracked product to obtain a first reactive oil-gas and a first precursor catalyst; or, feeding the first catalytic cracked product into a fluidized bed reactor for catalytic cracking, followed by gas-solid separation to obtain a second reactive oil-gas and a second precursor catalyst; introducing a continuous catalyst, heavy distillate oil, and a second catalyst stream into an upflow reactor for catalytic cracking, followed by gas-solid separation to obtain a third oil-gas and a third precursor catalyst; separating low-carbon olefins and light aromatics from the reactive oil-gas, and separating the light olefin fraction, returning the light olefin fraction to the fluidized bed reactor or the upflow reactor. This method can significantly improve the yield of low-carbon olefins and light aromatics and the economic efficiency of the equipment.

Description

Technical Field

[0001] This application relates to petroleum refining and petrochemical processing, specifically to a method and apparatus for the catalytic cracking of full-fraction hydrocarbon feedstock to produce low-carbon olefins and BTX. Background Technology

[0002] With the continued slowdown in the growth rate of refined oil consumption, the demand for basic organic feedstocks, such as low-carbon olefins and aromatics, is growing rapidly, making chemical feedstock refineries a future development trend. Currently, chemical feedstock refineries mainly have three configurations: First, crude oil undergoes pretreatment such as solvent deasphalting or hydrorefining before directly entering the steam cracking unit to produce chemical feedstocks; however, this method is generally limited to light crude oil. Second, heavy naphtha is maximized through hydrocracking of various crude oil fractions, followed by maximum aromatics production through a reforming unit. Third, the light fraction of crude oil enters the steam cracking unit, while the heavy fraction enters the catalytic cracking unit to maximize the production of low-carbon olefins. All three methods have been industrialized, with chemical yields ranging from 35% to 55%. It can be seen that the existing chemical feedstock refinery configuration mainly relies on a combination of multiple core units, including steam cracking, reforming, hydrorefining, hydrocracking, and catalytic cracking. Among these, catalytic cracking technology has unique advantages in terms of chemical feedstock production and feedstock adaptability, and can simultaneously produce propylene, ethylene, and BTX.

[0003] Chinese patent CN1978411B discloses a combined process for producing small molecule olefins. In this method, a catalytic cracking catalyst and cracking feedstock are mixed and contacted in a reactor. The spent catalyst and reaction oil / gas are separated. The spent catalyst is sent to a regenerator for coking regeneration. The regenerated hot catalyst is divided into two parts. One part of the regenerated hot catalyst is returned to the reactor mentioned above. The other part of the regenerated hot catalyst is first mixed and contacted with heavy petroleum hydrocarbons in another reactor for pre-coking. The C4-C8 olefin feedstock is then mixed and contacted with the coked catalyst to undergo a catalytic cracking reaction, separating the spent catalyst reaction oil / gas. This spent catalyst, along with the spent catalyst from the previous step, is sent to the regenerator for coking regeneration. The separation of the reaction oil / gas yields the target product, propylene, and other small molecule olefins. This method can highly selectively convert olefin-rich light feedstocks into small molecule olefin products such as propylene, while maintaining the thermal balance of the equipment itself.

[0004] Chinese patent CN102899078A discloses a catalytic cracking method for propylene production. This method is based on a combined reactor consisting of a dual riser and a fluidized bed. First, heavy feedstock oil and a first catalyst are introduced into a first riser reactor for reaction. After oil-catalyst separation, the oil enters a separation system. Cracked heavy oil is then introduced into a second riser reactor to react with the catalyst introduced into the second riser reactor. Light hydrocarbons are also introduced into the second riser reactor to react with the mixture formed by the reaction of the cracked heavy oil and the second cracking catalyst. These light hydrocarbons include C4 hydrocarbons or gasoline fractions obtained from the product separation system. Finally, the oil and gas mixture from the second riser reactor is introduced into a fluidized bed reactor for further reaction with the catalyst. Through process optimization and the use of a suitable catalyst, selective conversion of different feedstocks is achieved, resulting in high propylene and butene yields.

[0005] Chinese patent CN101045667B discloses a combined catalytic conversion method for producing high yields of low-carbon olefins. In this method, heavy oil feedstock is contacted with a regenerated catalyst and optionally a coking catalyst in a downflow reactor. At least a portion of the separated products, excluding low-carbon olefins, is introduced into a riser reactor to react with the regenerated catalyst. After the riser reaction, the catalyst is introduced into the pre-rise section of the downflow reactor, mixed with the regenerated catalyst entering the downflow reactor, and then contacted with the heavy oil feedstock. This method employs a combined reactor configuration where the heavy oil feedstock reacts in a downflow reactor and the intermediate olefin product reacts in a riser reactor, thereby increasing the yield of low-carbon olefins.

[0006] Chinese patent CN109370644A discloses a method for producing low-carbon olefins and aromatics through catalytic cracking of crude oil. This method separates crude oil into light and heavy fractions with a cutting point between 150℃ and 300℃. The light and heavy fractions react in different reaction zones within the same reactor. The catalyst primarily consists of aluminosilicates composed of silica and alumina, including alkali metal oxides, alkaline earth metal oxides, titanium and iron oxides, and oxides of vanadium and nickel. This method is a solution proposed for the catalytic cracking of crude oil to produce low-carbon olefins, based on a dense-phase conveyed bed reactor for heavy oil catalytic cracking.

[0007] The above methods have been studied from aspects such as the development of new reactor structures, the research and development of new catalytic materials, and the control of reaction depth to improve propylene selectivity. They have proposed methods for catalytic cracking to produce low-carbon olefins and aromatics, but there are still no preparation methods and reactor structures for maximizing the production of chemical feedstocks from crude oil. Summary of the Invention

[0008] The purpose of this disclosure is to propose an apparatus and method suitable for processing hydrocarbon feedstocks for catalytic cracking, in order to maximize the utilization of hydrocarbon feedstocks to produce low-carbon olefins and BTX, taking into account the different hydrocarbon compositions and cutting temperatures of various hydrocarbon feedstocks.

[0009] To achieve the above objectives, this disclosure provides a method for producing low-carbon olefins and light aromatics through catalytic cracking of hydrocarbon feedstock oil, the method comprising the following steps:

[0010] S1. The hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil, wherein the weight ratio of the light distillate oil to the heavy distillate oil (light distillate oil / heavy distillate oil) is X;

[0011] S2. The light distillate oil and the first catalyst are introduced into the first downward reactor to carry out the first catalytic cracking to obtain the material after the first catalytic cracking.

[0012] Optionally, in S2', the material after the first catalytic cracking is introduced into a fluidized bed reactor for a second catalytic cracking to obtain the material after the second catalytic cracking.

[0013] S3. Perform gas-solid separation on the material after the first catalytic cracking to obtain the first reaction oil and gas and the first catalyst to be generated, or perform gas-solid separation on the material after the second catalytic cracking to obtain the second reaction oil and gas and the second catalyst to be generated.

[0014] S4. The continuous catalyst, the heavy distillate oil, and the second catalyst are introduced into the second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain third reaction oil and gas and third catalyst to be generated; the continuous catalyst is at least a portion of the first catalyst to be generated or at least a portion of the second catalyst to be generated; the weight ratio of the second catalyst to the continuous catalyst (second catalyst / continuous catalyst) is R.

[0015] S5. Separate low-carbon olefins and light aromatics from any one of the first, second, and third reacting oil and gas, or a mixture of the first and third reacting oil and gas, or a mixture of the second and third reacting oil and gas, and separate the light olefin fraction, returning the light olefin fraction to the second upward reactor in step S4 or the fluidized bed reactor in step S2'.

[0016] The R and X satisfy the following relationship:

[0017] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0018] T0 is the temperature (in °C) when the second catalyst enters step S4, and T3 is the outlet temperature (in °C) of the second upward reactor.

[0019] Optionally, in the method of this disclosure, the outlet temperature T3 of the second upward reactor is 530-650°C, preferably 560-640°C, more preferably 580-630°C, and even more preferably 600-630°C; and / or, the temperature T0 when the second catalyst enters step S4 is 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C.

[0020] Optionally, in the method of this disclosure, in step S1, the hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil at any temperature between the cutting point and 100-400°C, such that the weight ratio of the light distillate oil to the heavy distillate oil (light distillate oil / heavy distillate oil) is X.

[0021] Optionally, in the method of this disclosure, the conditions for the first catalytic cracking in the first downward-flowing reactor include: an outlet temperature of 610-720°C, a gas-solid residence time of 0.1-3.0 seconds, and a catalyst-to-oil ratio of 15-80; and / or, the conditions for the second catalytic cracking in the fluidized bed reactor include: a reaction temperature of 600-690°C and a mass hourly space velocity of 2-20 h⁻¹. -1 ; and / or, in the second upward reactor, the conditions for the third catalytic cracking include: a gas-solid residence time of 0.5-8 seconds and an agent-to-oil ratio of 8-40.

[0022] Optionally, in the method of this disclosure, the conditions for the first catalytic cracking in the first downward-flowing reactor include: an outlet temperature of 650-690°C, a gas-solid residence time of 0.5-1.5 seconds, and a catalyst-to-oil ratio of 25-65; and / or, the conditions for the second catalytic cracking in the fluidized bed reactor include: a reaction temperature of 640-670°C and a mass hourly space velocity (MSV) of 4-12 h⁻¹. -1 ; and / or, in the second upward reactor, the conditions for the third catalytic cracking include: a gas-solid residence time of 1.5-5 seconds and an agent-to-oil ratio of 10-30.

[0023] Optionally, in the method of this disclosure, in step S4, the continuous catalyst is first mixed with the second catalyst, and then a subsequent catalytic cracking reaction is carried out; and / or, if step S2' exists, in the gas-solid separation of step S3, the separated catalyst is stripped to obtain a second catalyst to be produced; and / or, in step S4, the light olefin fraction from step S5 is contacted with the mixture of the second catalyst and the continuous catalyst before the heavy distillate oil for catalytic cracking; preferably, the light olefin fraction is contacted with the mixture of the second catalyst and the continuous catalyst 0.3-1.0 seconds before the heavy distillate oil for catalytic cracking, more preferably, the light olefin fraction is contacted with the mixture of the second catalyst and the continuous catalyst 0.4-0.8 seconds before the heavy distillate oil for catalytic cracking; and / or, the method has a step S0 before step S1, wherein the hydrocarbon feedstock oil is desalted and dehydrated, and the resulting dehydrated and desalted hydrocarbon feedstock oil is introduced into step S1 for cutting.

[0024] Optionally, the method of this disclosure further includes: in the gas-solid separation of step S4, stripping the separated catalyst to obtain a third regenerated catalyst; and / or, subjecting the third regenerated catalyst and optionally a first or second regenerated catalyst that did not enter the second upward reactor to coke regeneration at a temperature of 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C, to obtain a regenerated catalyst; and / or, any one of the first reaction gas, the second reaction gas, and the third reaction gas, or a mixture of the first and third reaction gas, or the second reaction gas. The mixture of the first and third reaction oil and gas is separated to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel and slurry, from which low-carbon olefins and light aromatics are separated, and a light olefin fraction is separated; and / or, if step S2' is not present, in step S5, a light olefin fraction is separated from either the first or third reaction oil and gas or a mixture of both, and the light olefin fraction is returned to the second upward reactor of step S4; if step S2' is present, in step S5, a light olefin fraction is separated from either the second or third reaction oil and gas or a mixture of both, and the light olefin fraction is returned to the fluidized bed reactor of step S2'.

[0025] Optionally, in the method of this disclosure, the hydrocarbon-containing feedstock is one or a mixture of two or more of crude oil, coal liquefaction oil, synthetic oil, oil sands oil, shale oil, tight oil and animal and vegetable oils, or hydrotreated oils of each of their respective fractions or their respective heavy fractions.

[0026] Optionally, in the method disclosed herein, the first catalyst and the second catalyst each independently comprise an active component and a support, wherein the active component is at least one selected from ultrastable Y-type zeolite with or without rare earth elements, ZSM-5 series zeolite, high-silica zeolite with a five-membered ring structure, and β-zeolite, and the support is at least one selected from alumina, silicon oxide, amorphous aluminosilicate, zirconium oxide, titanium oxide, boron oxide, and alkaline earth metal oxides.

[0027] Optionally, in the method of this disclosure, the first catalyst and the second catalyst each independently include a regenerated catalyst, preferably the first catalyst and the second catalyst are regenerated catalysts, and / or, all of the first catalyst to be regenerated or all of the second catalyst to be regenerated are used as continuous catalysts.

[0028] This disclosure also provides an apparatus for the catalytic cracking of hydrocarbon feedstock to produce low-carbon olefins and light aromatics, the apparatus comprising the following units:

[0029] A hydrocarbon-containing feedstock cutting unit cuts the hydrocarbon-containing feedstock into light distillate and heavy distillate, such that the weight ratio of the light distillate to the heavy distillate (light distillate / heavy distillate) is X.

[0030] In the first downward reaction unit, the light distillate oil and the first catalyst are introduced from above the reaction unit to carry out the first catalytic cracking, and the material after the first catalytic cracking is obtained below the reaction unit.

[0031] An optional fluidized bed reaction unit is used, wherein the material after the first catalytic cracking is introduced and subjected to a second catalytic cracking to obtain the material after the second catalytic cracking;

[0032] The first gas-solid separation unit introduces the material after the first catalytic cracking for gas-solid separation to obtain the first reactive oil and gas and the first catalyst to be generated, or introduces the material after the second catalytic cracking for gas-solid separation to obtain the second reactive oil and gas and the second catalyst to be generated.

[0033] In the second upward-flowing reaction unit, a continuous catalyst, a second catalyst stream, and the heavy distillate oil are introduced from below the reaction unit for third catalytic cracking. The product after the third catalytic cracking is obtained above the reaction unit. The continuous catalyst is at least a portion of the first spent catalyst or at least a portion of the second spent catalyst. The weight ratio of the second catalyst stream to the continuous catalyst (second catalyst stream / continuous catalyst) is R.

[0034] The second gas-solid separation unit introduces the material after the third catalytic cracking for gas-solid separation to obtain the third reaction oil and gas and the third catalyst to be generated.

[0035] The separation unit introduces any one of the first reaction oil and gas, the second reaction oil and gas, and the third reaction oil and gas, or a mixture of the first reaction oil and gas and the third reaction oil and gas, or a mixture of the second reaction oil and gas and the third reaction oil and gas, to separate low-carbon olefins and light aromatics, and to separate the light olefin fraction, and to return the light olefin fraction to the second upward reaction unit or the fluidized bed reaction unit.

[0036] Wherein, R and X satisfy the following relationship:

[0037] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0038] T0 is the temperature (in °C) when the second catalyst enters the second upward reaction unit, and T3 is the outlet temperature (in °C) of the second upward reaction unit.

[0039] Optionally, the apparatus of this disclosure further includes a regeneration unit, wherein the third spent catalyst and optionally a first or second spent catalyst that has not entered the second upward reactor are introduced and subjected to coke burn-off regeneration at a temperature of 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C, to obtain a regenerated catalyst.

[0040] Optionally, in the apparatus disclosed herein, when the apparatus includes a fluidized bed reaction unit, the first gas-solid separation unit further includes a stripping unit, wherein the catalyst obtained from the gas-solid separation is stripped to obtain a second catalyst to be produced.

[0041] The second gas-solid separation unit also includes a stripping unit, wherein the catalyst obtained from the gas-solid separation is stripped to obtain a third catalyst to be produced.

[0042] Optionally, in the apparatus disclosed herein, the apparatus further includes a dehydration and desalting unit, wherein the hydrocarbon-containing feedstock oil is subjected to desalting and dehydration treatment, and the resulting dehydrated and desalted hydrocarbon-containing feedstock oil is introduced into a hydrocarbon-containing feedstock oil cutting unit for cutting.

[0043] Optionally, in the apparatus of this disclosure, the location of the continuous catalyst and the second stream of catalyst in the second upward reaction unit is upstream of the feed inlet of the light olefin fraction.

[0044] Optionally, in the apparatus of this disclosure, in the second upward reaction unit, the feed inlet of the light olefin fraction from the separation unit is upstream of the feed inlet of the heavy distillate oil.

[0045] Technical effect

[0046] In this disclosure, using the specific method described above, based on the hydrocarbon composition characteristics and cracking reaction properties of different fractions of the hydrocarbon-containing feedstock, the feedstock is divided into light and heavy fractions. The light fraction is cracked in a downflow reactor at high temperature and with a short residence time, which can selectively produce low-carbon olefins and BTX while significantly reducing methane formation. Meanwhile, for the heavy fraction, using an upflow reactor maximizes the production of low-carbon olefins and BTX.

[0047] In addition, in this disclosure, by setting a fluidized bed reactor at the bottom of the first downward-flowing reactor, the light olefins in the catalytically cracked material can be further converted, thereby maximizing the production of low-carbon olefins.

[0048] In this disclosure, the light distillate oil has a short residence time in the first downward-flowing reactor, resulting in low coke formation and high yields of low-carbon olefins and BTX. Furthermore, in the fluidized bed reactor, the light olefin fraction is further converted. Therefore, the first spent catalyst exiting the first downward-flowing reactor or the second spent catalyst exiting the fluidized bed reactor still possesses high activity, and coke is loaded onto the catalyst. When this catalyst is used for the catalytic cracking of heavy distillate oil in the second upward-flowing reactor, the yield of low-carbon olefins can be increased, and the formation of dry gas and coke can be suppressed.

[0049] More importantly, in this disclosure, by ensuring that the weight ratio (X) of the light distillate oil and the heavy distillate oil obtained from the cutting meets a specific relationship with the weight ratio (R) of the second catalyst and the continuous catalyst, the cutting ratio can be flexibly adjusted according to the different types of hydrocarbon feedstock oil. Correspondingly, the weight ratio of the second catalyst and the continuous catalyst can be adjusted so that the catalyst activity in the second upward reactor is more matched with the composition of the heavy distillate oil. This can maximize the production of low-carbon olefins and BTX while significantly reducing the yield of by-products such as dry gas and coke.

[0050] In addition, through the above technical solution, the method for producing low-carbon olefins and BTX by catalytic cracking of hydrocarbon feedstock provided in this disclosure can significantly improve the yield of low-carbon olefins and light aromatics and the economic efficiency of the equipment.

[0051] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0052] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0053] Figure 1 This is a schematic diagram of one embodiment of the apparatus disclosed herein.

[0054] Figure 2 This is a schematic diagram of another embodiment of the apparatus disclosed herein.

[0055] Explanation of reference numerals in the attached figures

[0056] Detailed Implementation

[0057] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0058] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0059] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0060] In this application, except where expressly stated, any matters or issues not mentioned are directly applicable to those known in the art without any modification. Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or concepts shall be considered part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider such combination to be clearly unreasonable.

[0061] This disclosure provides a method for producing low-carbon olefins and light aromatics by catalytic cracking of hydrocarbon feedstock, the method comprising the following steps:

[0062] S1. The hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil, wherein the weight ratio of the light distillate oil to the heavy distillate oil (light distillate oil / heavy distillate oil) is X;

[0063] S2. The light distillate oil and the first catalyst are introduced into the first downward reactor to carry out the first catalytic cracking to obtain the material after the first catalytic cracking.

[0064] Optionally, in S2', the material after the first catalytic cracking is introduced into a fluidized bed reactor for a second catalytic cracking to obtain the material after the second catalytic cracking.

[0065] S3. Perform gas-solid separation on the material after the first catalytic cracking to obtain the first reaction oil and gas and the first catalyst to be generated, or perform gas-solid separation on the material after the second catalytic cracking to obtain the second reaction oil and gas and the second catalyst to be generated.

[0066] S4. The continuous catalyst, the heavy distillate oil, and the second catalyst are introduced into the second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain third reaction oil and gas and third catalyst to be generated; the continuous catalyst is at least a portion of the first catalyst to be generated or at least a portion of the second catalyst to be generated; the weight ratio of the second catalyst to the continuous catalyst (second catalyst / continuous catalyst) is R.

[0067] S5. Separate low-carbon olefins and light aromatics from any one of the first, second, and third reacting oil and gas, or a mixture of the first and third reacting oil and gas, or a mixture of the second and third reacting oil and gas, and separate the light olefin fraction, returning the light olefin fraction to the second upward reactor in step S4 or the fluidized bed reactor in step S2'.

[0068] The R and X satisfy the following relationship:

[0069] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0070] T0 is the temperature (in °C) when the second catalyst enters step S4, and T3 is the outlet temperature (in °C) of the second upward reactor.

[0071] In this disclosure, the first reaction oil gas, the second reaction oil gas and the third reaction oil gas, or a mixture of any one or more thereof, are sometimes referred to simply as reaction oil gas.

[0072] In this disclosure, low-carbon olefins refer to ethylene, propylene, butene, and their isomers. Light aromatics refer to BTX, namely benzene, toluene, and xylene. In this disclosure, low-carbon olefins can be separated from dry gas, C3 fraction, and C4 fraction; light aromatics can be separated from light gasoline and heavy gasoline.

[0073] In this disclosure, C3 fraction refers to hydrocarbons with three carbon atoms in the reacted oil and gas, including propane and propylene; C4 fraction refers to hydrocarbons with four carbon atoms in the reacted oil and gas, including butane, butene and their isomers; light gasoline refers to all or part of the fractions in the reacted oil and gas with a distillation range of 30-90°C, wherein "partial fraction" refers to a fraction with a distillation range of a portion of the temperature range between 30-90°C (e.g., a distillation range of 30-60°C, 40-60°C, or 60-90°C); heavy gasoline refers to the fractions in the reacted oil and gas with a distillation range of 30-200°C, excluding light gasoline.

[0074] In this disclosure, light distillate oil and heavy distillate oil refer to the light fraction obtained after cutting hydrocarbon-containing feedstock oil at a certain cutting temperature, and the remaining portion is called heavy distillate oil. Those skilled in the art can cut hydrocarbon-containing feedstock oil according to methods known in the art (including but not limited to fractionation, distillation, etc.), as long as the weight ratio of the light distillate oil to the heavy distillate oil (light distillate oil / heavy distillate oil) is X, and X satisfies the following relationship of this disclosure. In one embodiment of this disclosure, X is between any two values ​​selected from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0. In one embodiment of this disclosure, X is 0.1-2.0, preferably 0.12-1.0, and more preferably 0.15-0.6.

[0075] In one embodiment of this disclosure, in step S1, the hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil at any temperature between 100-400°C, such that the weight ratio of the light distillate oil to the heavy distillate oil (light distillate oil / heavy distillate oil) is X. In one embodiment of this disclosure, the cutting point is, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, or 400°C.

[0076] In this disclosure, the hydrocarbon-containing feedstock can be any type of feedstock known in the art (in this invention, hydrocarbon-containing feedstock is sometimes simply referred to as feedstock), for example, it can be one or a mixture of two or more of crude oil, coal liquefaction oil, synthetic oil, oil sands oil, shale oil, tight oil, and animal and vegetable oils, or hydrotreated oils of a portion of each of these, or hydrotreated oils of a heavy fraction of each of these. In one embodiment of this disclosure, the hydrocarbon-containing feedstock is preferably crude oil, a portion of crude oil, or hydrotreated oils of heavy oil derived from crude oil. Those skilled in the art know that a "portion of oil" can be obtained by conventional processing of the feedstock, including but not limited to atmospheric distillation and vacuum distillation. Those skilled in the art can determine the method of conventional processing as needed. In one embodiment of this disclosure, crude oil can be used as the hydrocarbon-containing feedstock of this disclosure. Alternatively, crude oil can be subjected to atmospheric or vacuum distillation, and the remaining fraction after extracting a portion of the fraction (the portion of crude oil) can be used as the hydrocarbon-containing feedstock of this disclosure. Or, the product of hydrotreated heavy oil derived from crude oil (hydrotreated oil of heavy oil) can be used as the hydrocarbon-containing feedstock of this disclosure. It is known in the art that hydrotreating includes, but is not limited to, hydrodesulfurization, hydronitrogenation, hydrodemetallization, and hydrosaturation.

[0077] In one embodiment of this disclosure, the method has a step S0 before step S1, wherein the hydrocarbon-containing feedstock oil is desalted and dehydrated, and the resulting dehydrated and desalted hydrocarbon-containing feedstock oil is introduced into step S1 for cutting.

[0078] According to this disclosure, in step S2, the conditions for the first catalytic cracking in the first downward-flowing reactor include: the outlet temperature of the first downward-flowing reactor is 610-720°C, preferably 650-690°C. The conditions for the first catalytic cracking also include: a gas-solid residence time of 0.1-3.0 seconds, preferably 0.5-1.5 seconds. In the first downward-flowing reactor, the catalyst-to-oil ratio can be a commonly used catalyst-to-oil ratio in catalytic cracking (based on the weight ratio of catalyst / light distillate oil), for example, 15-80, preferably 25-65.

[0079] In this disclosure, there are no limitations on the method by which the light distillate oil and the first catalyst are introduced into the first downward-flowing reactor, as long as they are introduced at the top of the first downward-flowing reactor. Preferably, the light distillate oil and the first catalyst are introduced into the first downward-flowing reactor through different feed inlets.

[0080] In this disclosure, the first catalyst is not limited and can be any catalyst known in the art that can be used for catalytic cracking of crude oil. For example, the first catalyst may include an active component and a support, wherein the active component is at least one selected from ultrastable Y-type zeolite with or without rare earth elements, ZSM-5 series zeolite, high-silica zeolite with a five-membered ring structure, and β-zeolite. The support is at least one selected from alumina, silica, amorphous aluminosilicate, zirconium oxide, titanium oxide, boron oxide, and alkaline earth metal oxides.

[0081] In one embodiment of this disclosure, the structure of the first downward-flowing reactor is not particularly limited, as long as it can be fed from the top and discharged from the bottom. For example, it can be a downward-flowing tube reactor with constant or variable diameter.

[0082] In this disclosure, since no additional heat source is used in the first downward-flowing reactor, the outlet temperature of the first downward-flowing reactor reflects the reaction temperature in the reactor. In this disclosure, the degree of catalytic cracking of the light distillate oil in the first downward-flowing reactor can be adjusted by regulating conditions such as the temperature of the first catalyst stream, the gas-solid residence time in the reactor, and the outlet temperature of the first downward-flowing reactor.

[0083] In one embodiment of this disclosure, the first catalyst stream is a fresh catalyst. In another embodiment of this disclosure, the first catalyst stream comprises a regenerated catalyst from a regenerator. Preferably, the first catalyst stream is a regenerated catalyst from a regenerator.

[0084] In this disclosure, there is no particular limitation on the temperature of the first catalyst entering the downflow reactor, as long as it can undergo catalytic cracking upon contact with the light distillate oil and meets the first catalytic cracking conditions described above. When using a regenerated catalyst as the first catalyst, the first catalyst is directly fed into the regenerator via a first catalyst (regenerated catalyst) feed pipe. Since the feed pipe between the regenerator and the first downflow reactor is short, the temperature of the first catalyst can be considered as the temperature of the regenerator or the temperature at which the regenerated catalyst leaves the regenerator (the temperature at the regenerator outlet). In one embodiment of this disclosure, the temperature of the first catalyst entering the downflow reactor is the temperature of the regenerator or the temperature at which the regenerated catalyst leaves the regenerator (the temperature at the regenerator outlet), typically 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C. Furthermore, the catalyst from the regenerator can be further heated or cooled as needed before being fed into the first downflow reactor. In the method of this disclosure, during start-up, fresh catalyst can be heated to the required temperature and then introduced into the first downflow reactor; thereafter, regenerated catalyst from the regenerator can be used directly. In one embodiment of this disclosure, the first stream of catalyst is preferably fed directly into the regenerator without further heating or cooling.

[0085] In this disclosure, when introducing the light distillate oil into the first downward-flowing reactor, the light distillate oil can be preheated as needed. The temperature of the preheated light distillate oil is, for example, 30-100°C. Alternatively, the light distillate oil can be atomized with water vapor before being introduced into the first downward-flowing reactor using water vapor as a carrier.

[0086] In this disclosure, the feedstock after the first catalytic cracking includes a first reactive oil and gas obtained from the catalytic cracking of light distillate oil and a first spent catalyst after the first catalyst has been coked (carbonized). This first spent catalyst still possesses high activity and is loaded with coke. When introduced as a continuous catalyst into the subsequent second upflow reactor, it facilitates the catalytic cracking of heavy distillate oil, increases the yield of low-carbon olefins, and suppresses the formation of dry gas and coke.

[0087] In this disclosure, in step S3, the material after the first catalytic cracking is subjected to gas-solid separation to obtain a first reaction oil and gas and a first catalyst to be generated. The method of gas-solid separation is not particularly limited, and methods known in the art can be used, such as using a settling tank or a cyclone separator to separate the catalyst from the first reaction oil and gas.

[0088] In one embodiment of this disclosure, the first reaction oil and gas are separated to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry, from which low-carbon olefins and light aromatics are separated, and a light olefin fraction is also separated. The C4 fraction and / or light gasoline are the light olefin fraction. In one embodiment of this disclosure, the first reaction oil and gas are introduced into a fractionating device or a gas separator for fractionation to achieve the above separation. In one embodiment of this disclosure, the light olefin fraction is introduced into the second upward reactor in step S4 below.

[0089] In one embodiment of this disclosure, at least a portion of the first awaiting catalyst is introduced as a continuous catalyst into the second upward reactor. In another embodiment of this disclosure, the first awaiting catalyst that does not enter the second upward reactor is introduced into a regeneration step, where catalyst regeneration is performed. Preferably, all of the first awaiting catalyst is introduced as a continuous catalyst into the second upward reactor, in which case the amount of the first awaiting catalyst as a continuous catalyst substantially corresponds to the amount of the first catalyst stream.

[0090] In one embodiment of this disclosure, the material after the first catalytic cracking is subjected to gas-solid separation, and the separated catalyst is further stripped to remove the adsorbed hydrocarbon products to obtain the first catalyst to be generated.

[0091] In one embodiment of this disclosure, step S2' may be included after step S2 and before step S3, wherein the material after the first catalytic cracking is introduced into a fluidized bed reactor for a second catalytic cracking to obtain the material after the second catalytic cracking. Thus, the light olefin fraction can be further converted, and the production of low-carbon olefins can be maximized.

[0092] In this disclosure, the "fluidized bed reactor" is also referred to as a "fluidized bed reactor," and its catalyst density is 150-450 kg / m³. 3 between.

[0093] According to this disclosure, in step S2', the conditions for the second catalytic cracking in the fluidized bed reactor include: a reaction temperature of 600-690°C, preferably 640-670°C. The conditions for the second catalytic cracking also include: a mass hourly space velocity (HHSV) of 2-20 h⁻¹. -1 4-12h preferred -1 .

[0094] According to one embodiment of this disclosure, instead of introducing a new catalyst, the material after the first catalytic cracking is directly introduced into the fluidized bed for catalytic cracking. According to another embodiment of this disclosure, no additional heat source is applied to the fluidized bed; instead, the heat from the material after the first catalytic cracking is utilized directly. The introduced material after the first catalytic cracking includes a first reaction oil-gas obtained from the catalytic cracking of light distillate oil and a first spent catalyst after the first catalyst has been coked (carbonized). This first spent catalyst still possesses high activity and can further deepen the catalytic cracking process in the fluidized bed reactor, further converting the light olefin fraction into low-carbon olefins.

[0095] According to one embodiment of this disclosure, a light olefin fraction is separated from the reaction oil and gas, and the light olefin fraction is returned to the fluidized bed reactor for further conversion into low-carbon olefins. More specifically, the reaction oil and gas is separated to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry, from which low-carbon olefins and light aromatics are separated, and the light olefin fraction is also separated. The C4 fraction and / or light gasoline are the light olefin fraction. In one embodiment of this disclosure, the reaction oil and gas are introduced into a fractionation unit or a gas separation unit to achieve the above separation.

[0096] In this disclosure, the feedstock after the second catalytic cracking includes a second reactive oil and gas and a second spent catalyst. This second spent catalyst still possesses high activity and is loaded with coke. When introduced as a continuous catalyst into the subsequent second upflow reactor, it facilitates the catalytic cracking of heavy distillate oil, increases the yield of low-carbon olefins, and inhibits the formation of dry gas and coke.

[0097] In this disclosure, in step S3, the material after the second catalytic cracking is subjected to gas-solid separation to obtain the second reaction oil and gas and the second catalyst to be generated. The method of gas-solid separation is not particularly limited, and methods known in the art can be used, such as using a settling tank or a cyclone separator to separate the catalyst from the second reaction oil and gas.

[0098] In one embodiment of this disclosure, the second reaction oil and gas are separated to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry, from which low-carbon olefins and light aromatics are separated, and a light olefin fraction is also separated. The C4 fraction and / or light gasoline are the light olefin fraction. In one embodiment of this disclosure, the second reaction oil and gas are introduced into a fractionation unit or a gas separation unit to achieve the above separation.

[0099] In one embodiment of this disclosure, the material after the second catalytic cracking is subjected to gas-solid separation, and the separated catalyst is further stripped to remove adsorbed hydrocarbon products, thereby obtaining a second spent catalyst. In this disclosure, at least a portion of the second spent catalyst is introduced as a continuous catalyst into the second upward reactor described below.

[0100] In one embodiment of this disclosure, a second batch of spent catalyst that has not yet entered the second upward reactor is introduced into a regeneration step, where catalyst regeneration is performed. Preferably, all of the second batch of spent catalyst is introduced into the second upward reactor as a continuous catalyst, wherein the amount of the second batch of spent catalyst as a continuous catalyst substantially corresponds to the amount of the first catalyst stream.

[0101] In this disclosure, in step S4, a continuous catalyst, the heavy distillate oil, and a second catalyst are introduced into a second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain a third reaction oil and gas and a third catalyst to be generated; the continuous catalyst is at least a portion of the first catalyst to be generated or at least a portion of the second catalyst to be generated.

[0102] In one embodiment of this disclosure, the conditions for the third catalytic cracking in the second upward reactor include: the outlet temperature T3 of the second upward reactor is 530-650°C, preferably 560-640°C, more preferably 580-630°C, and even more preferably 600-630°C. The conditions for the third catalytic cracking also include: a gas-solid residence time of 0.5-8 seconds, preferably 1.5-5 seconds. In the second upward reactor, the catalyst-to-oil ratio can be a commonly used catalyst-to-oil ratio in catalytic cracking (based on the weight ratio of catalyst / heavy distillate oil), for example, 8-40, preferably 10-30.

[0103] In one embodiment of this disclosure, in step S4, the continuous catalyst is first mixed with the second catalyst stream before subsequent catalytic cracking reaction. More specifically, in one embodiment of this disclosure, the continuous catalyst and the second catalyst stream are each independently fed to the bottom of the second upward reactor, mixed, and the mixed catalyst (hereinafter sometimes referred to as catalyst mixture or mixed catalyst) is used for catalytic cracking reaction in the second upward reactor. In one embodiment of this disclosure, after the continuous catalyst and the second catalyst stream are mixed in the bottom region of the second upward reactor, a pre-lifting medium is used to lift the mixed catalyst in the second upward reactor for downstream catalytic cracking reaction. In one embodiment of this disclosure, the pre-lifting medium can be dry gas, water vapor, or a mixture thereof.

[0104] In one embodiment of this disclosure, in step S4, the second catalyst is not limited and can be any catalyst known in the art that can be used for catalytic cracking of crude oil. For example, the second catalyst includes an active component and a support. The active component is at least one selected from ultrastable Y-type zeolite with or without rare earth elements, ZSM-5 series zeolite, high-silica zeolite with a five-membered ring structure, and β-zeolite. The support is at least one selected from alumina, silica, amorphous aluminosilicate, zirconium oxide, titanium oxide, boron oxide, and alkaline earth metal oxides.

[0105] In one embodiment of this disclosure, the structure of the second upward reactor is not particularly limited, as long as it can be fed from the bottom and discharged from the top. For example, it can be a riser reactor with equal or variable diameter, a riser reactor with equal or variable diameter, or a fluidized bed composite reactor.

[0106] In one embodiment of this disclosure, the second catalyst is a fresh catalyst. In one embodiment of this disclosure, the second catalyst includes a regenerated catalyst from a regenerator. In one embodiment of this disclosure, the second catalyst is a regenerated catalyst from a regenerator. When a fresh catalyst is used as the second catalyst, the catalyst needs to be preheated so that the temperature of the fresh catalyst entering step S4 satisfies the relationship of this disclosure. Preferably, the second catalyst is a regenerated catalyst from a regenerator.

[0107] In this disclosure, the weight ratio of the second catalyst to the continuous catalyst (second catalyst / continuous catalyst) is R, and R and X satisfy the following relationship:

[0108] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0109] T0 is the temperature (in °C) when the second catalyst enters step S4, and T3 is the outlet temperature (in °C) of the second upward reactor.

[0110] The inventors of this disclosure have surprisingly discovered that by making the cut ratio of light and heavy distillate oils of the hydrocarbon feedstock in step S1 (weight ratio of light distillate oil to heavy distillate oil) satisfy the above-mentioned relationship with the weight ratio of the second catalyst and the continuous catalyst (second catalyst to continuous catalyst), the hydrocarbon feedstock composition, cut ratio, and catalyst activity (especially the catalyst activity in the second upward reactor) can be better matched. This allows for maximizing the production of low-carbon olefins and BTX while significantly reducing the yield of dry gas and coke. Without being limited by any theory, the inventors of this disclosure speculate that the catalyst, as a continuous catalyst, is derived from a first or second spent catalyst. Due to the low coking in the first downflow reactor and the fluidized bed reactor, both the first and second spent catalysts possess high catalytic activity while being loaded with a certain amount of coke. This catalyst is mixed with a second stream catalyst (fresh catalyst or regenerated catalyst from a regenerator) in a certain proportion, and the mixing ratio is matched with the cutting ratio of the hydrocarbon feedstock, satisfying the above-mentioned relationship of this disclosure. The resulting catalyst maintains excellent catalytic activity without causing excessive coking of the heavy distillate due to excessively high catalyst activity, nor causing insufficient catalytic cracking of the heavy distillate due to excessively low catalyst activity. In this disclosure, the ratio of hydrocarbon feedstock cutting into light and heavy distillate oils satisfies a specific relationship with the mixing ratio of the continuous catalyst and the second stream catalyst. The activity of the mixed catalyst in the second upflow reactor can be adjusted according to the composition and cutting ratio of the hydrocarbon feedstock, thereby maximizing the yield of low-carbon olefins and BTX from the heavy distillate oil.

[0111] In one embodiment of this disclosure, (4.84×T0-3340) / (780+5×T0-6×T3) is greater than 0. In this disclosure, T0 is greater than T3.

[0112] In this disclosure, T0 refers to the temperature at which the second catalyst enters step S4. Specifically, it refers to the temperature at which the second catalyst (fresh or regenerated catalyst) enters the second upward reactor, that is, its temperature at the bottom of the second upward reactor before mixing with the continuous catalyst. When a regenerated catalyst is used as the second catalyst, since the conveying pipe between the regenerator and the second upward reactor is short, the temperature of the regenerator or the temperature of the catalyst when it exits the regenerator (the temperature at the regenerator outlet) can be considered as the temperature at which the second catalyst enters step S4.

[0113] In one embodiment of this disclosure, the outlet temperature T3 of the second upward reactor is 530-650°C, preferably 560-640°C, more preferably 580-630°C, and even more preferably 600-630°C; and / or, the temperature T0 of the second catalyst entering step S4 is 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C.

[0114] In one embodiment of this disclosure, the third reaction oil and gas are separated to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry, from which low-carbon olefins and light aromatics are separated, and a light olefin fraction is also separated. The C4 fraction and / or light gasoline are the light olefin fraction. In one embodiment of this disclosure, the third reaction oil and gas are introduced into a fractionation unit or a gas separation unit to achieve the above separation.

[0115] In this disclosure, when step S2' is absent, in step S5, low-carbon olefins and light aromatics are separated from either the first reaction oil and gas or the third reaction oil and gas or a mixture of both, and the separated light olefin fraction is returned to the second upward reactor.

[0116] In this disclosure, when step S2' is present, in step S5, low-carbon olefins and light aromatics are separated from either the second reaction oil and gas or the third reaction oil and gas or a mixture of both, and the separated light olefin fraction is returned to the fluidized bed reactor.

[0117] In one embodiment of this disclosure, in step S4, the light olefin fraction from step S5 below contacts the catalyst mixture before the heavy distillate oil, undergoing a catalytic cracking reaction, and then the heavy distillate oil contacts the catalyst mixture again, undergoing a catalytic cracking reaction. Preferably, the light olefin fraction contacts the catalyst mixture 0.3-1.0 seconds before the heavy distillate oil. More preferably, the light olefin fraction contacts the catalyst mixture 0.4-0.8 seconds before the heavy distillate oil.

[0118] In one embodiment of this disclosure, the products of the third catalytic cracking are subjected to gas-solid separation to obtain a third reactive oil-gas and a third catalyst to be generated. The method of gas-solid separation is not particularly limited, and methods known in the art can be used, such as using a settling tank or a cyclone separator to separate the catalyst from the third reactive oil-gas.

[0119] In one embodiment of this disclosure, the material after third catalytic cracking is subjected to gas-solid separation. The separated catalyst is further stripped to remove adsorbed hydrocarbon products, yielding a third regenerated catalyst. In another embodiment of this disclosure, the third regenerated catalyst is fed into a regenerator for catalyst regeneration.

[0120] In one embodiment of this disclosure, the temperature of the regenerator is a temperature commonly used in the art, which can be 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C. In one embodiment of this disclosure, the temperature of the regenerator or the temperature of the catalyst when the regenerated catalyst exits the regenerator (the temperature at the regenerator outlet) can be regarded as the temperature at which the second stream of catalyst enters step S4. Therefore, in one embodiment of this disclosure, the temperature T0 at which the second stream of catalyst enters step S4 can be 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C.

[0121] In one embodiment of this disclosure, the regenerated catalyst is used as a first-stream catalyst and a second-stream catalyst.

[0122] In this disclosure, in step S5, low-carbon olefins and light aromatics are separated from any one of the first, second, and third reaction gases, or a mixture of the first and third reaction gases, or a mixture of the second and third reaction gases, and a light olefin fraction is separated and returned to the second upward reactor in step S4 or the fluidized bed reactor in step S2'. More specifically, the reaction gases are separated to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry, from which low-carbon olefins and light aromatics are separated, and a light olefin fraction is separated. The C4 fraction and / or light gasoline are the light olefin fraction. Preferably, the reaction gases are introduced into a fractionation unit or a gas separation unit to achieve the above separation. In step S5, the first reaction oil and gas and the third reaction oil and gas can be separated separately, or they can be combined and then separated together; or the second reaction oil and gas and the third reaction oil and gas can be separated separately, or they can be combined and then separated together.

[0123] In one embodiment of this disclosure, the method for separating the light olefin fraction from the reaction oil and gas is not limited, and separation can be performed using methods known in the art, including but not limited to the following: after the reaction oil and gas enters the fractionation and absorption stabilization unit, liquefied petroleum gas (LPG) and stabilized gasoline are separated; the LPG enters a subsequent gas separation unit to separate C3 and C4 fractions; and the stabilized gasoline enters a light and heavy gasoline separation tower to separate light gasoline and heavy gasoline. The C4 fraction and / or light gasoline are the light olefin fraction. Low-carbon olefins and light aromatics can be separated from it.

[0124] More specifically, in one embodiment of this disclosure, a method for producing low-carbon olefins and light aromatics by catalytic cracking of hydrocarbon feedstock is provided, the method comprising the following steps:

[0125] S1. The hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil, wherein the weight ratio of the light distillate oil to the heavy distillate oil (light distillate oil / heavy distillate oil) is X;

[0126] S2. The light distillate oil and the first catalyst are introduced into the first downward reactor to carry out the first catalytic cracking to obtain the material after the first catalytic cracking.

[0127] S3. Perform gas-solid separation on the material after the first catalytic cracking to obtain the first reaction oil and gas and the first catalyst to be generated;

[0128] S4. The continuous catalyst, the heavy distillate oil, and the second catalyst are introduced into the second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain third reaction oil and gas and third catalyst to be generated; the continuous catalyst is at least a part of the first catalyst to be generated; the weight ratio of the second catalyst to the continuous catalyst (second catalyst / continuous catalyst) is R.

[0129] S5. Separate low-carbon olefins and light aromatics from either or a mixture of the first and third reaction oils and gases, and separate the light olefin fraction, returning the light olefin fraction to the second upward reactor in step S4.

[0130] The R and X satisfy the following relationship:

[0131] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0132] T0 is the temperature (in °C) when the second catalyst enters step S4, and T3 is the outlet temperature (in °C) of the second upward reactor.

[0133] More specifically, in one embodiment of this disclosure, a method for producing low-carbon olefins and light aromatics by catalytic cracking of hydrocarbon feedstock is provided, the method comprising the following steps:

[0134] S1. The hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil, wherein the weight ratio of the light distillate oil to the heavy distillate oil (light distillate oil / heavy distillate oil) is X;

[0135] S2. The light distillate oil and the first catalyst are introduced into the first downward reactor to carry out the first catalytic cracking to obtain the material after the first catalytic cracking.

[0136] S2', The material after the first catalytic cracking is introduced into a fluidized bed reactor for the second catalytic cracking to obtain the material after the second catalytic cracking;

[0137] S3. Perform gas-solid separation on the material after the second catalytic cracking to obtain the second reaction oil and gas and the second catalyst to be generated.

[0138] S4. The continuous catalyst, the heavy distillate oil, and the second catalyst are introduced into the second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain third reaction oil and gas and third catalyst to be generated; the continuous catalyst is at least a part of the second catalyst to be generated; the weight ratio of the second catalyst to the continuous catalyst (second catalyst / continuous catalyst) is R.

[0139] S5. Separate low-carbon olefins and light aromatics from either or a mixture of the second and third reaction oil gases, and separate the light olefin fraction, returning the light olefin fraction to the fluidized bed reactor of step S2'.

[0140] The R and X satisfy the following relationship:

[0141] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0142] T0 is the temperature (in °C) when the second catalyst enters step S4, and T3 is the outlet temperature (in °C) of the second upward reactor.

[0143] In one embodiment of this disclosure, the light olefin fraction is the C4 fraction in the reacted oil and / or the light gasoline.

[0144] This disclosure also provides the following technical solutions:

[0145] A1. A method for producing low-carbon olefins and light aromatics by catalytic cracking of hydrocarbon feedstock, the method comprising the following steps:

[0146] S1. The desalted and dehydrated hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil; the cutting point is any temperature between 100-400℃;

[0147] S2. The light distillate oil and the first catalyst are introduced into the first downward reactor to carry out the first catalytic cracking to obtain the material after the first catalytic cracking.

[0148] Optionally, in S2', the material after the first catalytic cracking is fed into a fluidized bed reactor for a second catalytic cracking to obtain the material after the second catalytic cracking.

[0149] S3. Perform gas-solid separation on the material after the first catalytic cracking to obtain the first reaction oil and gas and the first catalyst to be generated, or perform gas-solid separation on the material after the second catalytic cracking to obtain the second reaction oil and gas and the second catalyst to be generated.

[0150] S4. The continuous catalyst, the heavy distillate oil, and the second catalyst are introduced into the second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain third reaction oil and gas and third catalyst to be generated; the continuous catalyst is either the first catalyst to be generated or the second catalyst to be generated; the weight ratio of the second catalyst to the continuous catalyst is 0.2-5:1.

[0151] S5. Separate the light olefin fraction from the first and second reaction oil and gas, and return the light olefin fraction to the fluidized bed reactor or the second upflow reactor.

[0152] A2. According to the method described in A1, in step S1, the cutting point is any temperature between 200-380℃.

[0153] A3. According to the method described in A1, wherein in step S4, the weight ratio of the second catalyst to the continuous catalyst is 0.5-3:1.

[0154] A4. The method according to claim A1, wherein,

[0155] In the first downward-flowing reactor, the conditions for the first catalytic cracking include: the outlet temperature of the first downward-flowing reactor is 610-720℃, and the gas-solid residence time is 0.1-3.0 seconds;

[0156] In the fluidized bed reactor, the conditions for the second catalytic cracking include: a reaction temperature of 600-670℃ and a mass hourly space velocity of 2-20 h⁻¹. -1 ;

[0157] In the second upward reactor, the conditions for the third catalytic cracking include: the outlet temperature of the second upward reactor is 530-650℃, and the gas-solid residence time is 0.5-8 seconds.

[0158] A5. According to the method described in A4, where,

[0159] In the first downward-flowing reactor, the conditions for the first catalytic cracking include: the outlet temperature of the first downward-flowing reactor is 650-690℃, and the gas-solid residence time is 0.5-1.5 seconds;

[0160] In the fluidized bed reactor, the conditions for the second catalytic cracking include: a reaction temperature of 620-640℃ and a mass hourly space velocity of 4-12 h⁻¹. -1 ;

[0161] In the second upward reactor, the conditions for the third catalytic cracking include: the outlet temperature of the second upward reactor is 560-640℃, and the gas-solid residence time is 1.5-5 seconds.

[0162] A6. According to the method described in A1, where,

[0163] The light olefin fraction is catalytically cracked with the second catalyst 0.3-1.0 seconds before the heavy distillate oil; preferably, the light olefin fraction is catalytically cracked with the second catalyst 0.4-0.8 seconds before the heavy distillate oil.

[0164] A7. According to the method described in A1, the method further includes:

[0165] The third spent catalyst is regenerated by coking to obtain a regenerated catalyst;

[0166] The first oil and gas and the second oil and gas are separated to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel and oil slurry;

[0167] The light olefin fraction is the C4 fraction in the first oil and gas and the second oil and gas and / or the fraction in the first oil and gas and the second oil and gas within the range of 30-90°C.

[0168] A8. According to the method described in A1, the hydrocarbon-containing feedstock oil is one or a mixture of several of the following: conventional mineral oil, coal liquefaction oil, synthetic oil, oil sands oil, shale oil, tight oil, and animal and vegetable oils.

[0169] A9. According to the method described in A1, wherein the first catalyst and the second catalyst each independently comprise an active component and a support, wherein the active component is at least one selected from ultrastable Y-type zeolite with or without rare earth elements, ZSP series zeolite, high-silica zeolite with a five-membered ring structure, and β-zeolite.

[0170] A10. According to the method of A1, wherein the first catalyst and the second catalyst each independently comprise the regenerated catalyst.

[0171] This disclosure also provides an apparatus for the catalytic cracking of hydrocarbon feedstock to produce low-carbon olefins and light aromatics, the apparatus comprising the following units:

[0172] A hydrocarbon-containing feedstock cutting unit cuts the hydrocarbon-containing feedstock into light distillate and heavy distillate, such that the weight ratio of the light distillate to the heavy distillate (light distillate / heavy distillate) is X.

[0173] In the first downward reaction unit, the light distillate oil and the first catalyst are introduced from above the reaction unit to carry out the first catalytic cracking, and the material after the first catalytic cracking is obtained below the reaction unit.

[0174] An optional fluidized bed reaction unit is used, wherein the material after the first catalytic cracking is introduced and subjected to a second catalytic cracking to obtain the material after the second catalytic cracking;

[0175] The first gas-solid separation unit introduces the material after the first catalytic cracking for gas-solid separation to obtain the first reactive oil and gas and the first catalyst to be generated, or introduces the material after the second catalytic cracking for gas-solid separation to obtain the second reactive oil and gas and the second catalyst to be generated.

[0176] In the second upward-flowing reaction unit, a continuous catalyst, a second catalyst stream, and the heavy distillate oil are introduced from below the reaction unit for third catalytic cracking. The product after the third catalytic cracking is obtained above the reaction unit. The continuous catalyst is at least a portion of the first spent catalyst or at least a portion of the second spent catalyst. The weight ratio of the second catalyst stream to the continuous catalyst (second catalyst stream / continuous catalyst) is R.

[0177] The second gas-solid separation unit introduces the material after the third catalytic cracking for gas-solid separation to obtain the third reaction oil and gas and the third catalyst to be generated.

[0178] The separation unit introduces any one of the first reaction oil and gas, the second reaction oil and gas, and the third reaction oil and gas, or a mixture of the first reaction oil and gas and the third reaction oil and gas, or a mixture of the second reaction oil and gas and the third reaction oil and gas, to separate low-carbon olefins and light aromatics, and to separate the light olefin fraction, and to return the light olefin fraction to the second upward reaction unit or the fluidized bed reaction unit.

[0179] Wherein, R and X satisfy the following relationship:

[0180] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0181] T0 is the temperature (in °C) when the second catalyst enters the second upward reaction unit, and T3 is the outlet temperature (in °C) of the second upward reaction unit.

[0182] In this disclosure, T0 is the temperature (in °C) when the second catalyst enters the second upward reaction unit. Specifically, it refers to the temperature when the second catalyst enters the bottom of the second upward reaction unit, before mixing with the continuous catalyst.

[0183] In one embodiment of this disclosure, the apparatus further includes a regeneration unit, wherein the third spent catalyst and optionally a first or second spent catalyst that did not enter the second upward reactor are introduced for coke regeneration to obtain a regenerated catalyst. Preferably, only the third spent catalyst is introduced into the regeneration unit. In one embodiment of this disclosure, the temperature of the regeneration unit is a temperature commonly used in the art, which can be 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C.

[0184] In one embodiment of this disclosure, the outlet temperature T3 of the second upward reaction unit is 530-650°C, preferably 560-640°C, more preferably 580-630°C, and even more preferably 600-630°C.

[0185] In one embodiment of this disclosure, the temperature T0 when the second catalyst enters the second upward reaction unit is 690-750°C, preferably 700-740°C, more preferably 705-730°C, and even more preferably 710-725°C.

[0186] In one embodiment of this disclosure, the apparatus further includes a dehydration and desalting unit, wherein the hydrocarbon-containing feedstock oil is subjected to desalting and dehydration treatment, and the resulting dehydrated and desalted hydrocarbon-containing feedstock oil is introduced into a hydrocarbon-containing feedstock oil cutting unit for cutting.

[0187] In one embodiment of this disclosure, the structure of the first downward reaction unit is not particularly limited, as long as it can be fed from the top and discharged from the bottom. For example, it can be a downward tube reactor with constant or variable diameter.

[0188] In one embodiment of this disclosure, when there is no fluidized bed reaction unit, low-carbon olefins and light aromatics are separated from either the first reaction oil and gas or the third reaction oil and gas or a mixture thereof in the separation unit, and the separated light olefin fraction is returned to the second upward reaction unit.

[0189] In this disclosure, when a fluidized bed reactor unit is present, low-carbon olefins and light aromatics are separated from either the second reaction oil and gas or the third reaction oil and gas or a mixture thereof in a separation unit, and the separated light olefin fraction is returned to the fluidized bed reactor.

[0190] In one embodiment of this disclosure, the first gas-solid separation unit and the second gas-solid separation unit include devices known in the art that can achieve gas-solid separation, such as sedimentation tanks or cyclone separators.

[0191] In one embodiment of this disclosure, the apparatus further includes at least one stripping unit, which may be disposed in a gas-solid separation unit, wherein the catalyst obtained from gas-solid separation is stripped to remove the hydrocarbon products adsorbed therein.

[0192] More specifically, in one embodiment of this disclosure, when the apparatus includes a fluidized bed reaction unit, the first gas-solid separation unit further includes a stripping unit, wherein the catalyst obtained from the gas-solid separation is stripped to remove adsorbed hydrocarbon products, yielding a second catalyst to be produced. In one embodiment of this disclosure, the second gas-solid separation unit further includes a stripping unit, wherein the catalyst obtained from the gas-solid separation is stripped to remove adsorbed hydrocarbon products, yielding a third catalyst to be produced.

[0193] In one embodiment of this disclosure, a continuous catalyst and a second catalyst are introduced into the bottom of a second upward reaction unit, mixed, and then the mixed catalyst is used for subsequent catalytic cracking reactions.

[0194] In one embodiment of this disclosure, in the second upward reaction unit, the continuous catalyst and the second stream of catalyst are introduced upstream of the light olefin fraction feed inlet.

[0195] In one embodiment of this disclosure, in the second upward reaction unit, the light olefin fraction feed inlet is upstream of the heavy distillate oil feed inlet.

[0196] In one embodiment of this disclosure, the structure of the second upward reactor is not particularly limited, as long as it can be fed from the bottom and discharged from the top. For example, it can be a riser reactor with equal or variable diameter, a riser reactor with equal or variable diameter, or a fluidized bed composite reactor.

[0197] More specifically, this disclosure provides an apparatus for the catalytic cracking of hydrocarbon feedstock to produce low-carbon olefins and light aromatics, the apparatus comprising the following units:

[0198] A hydrocarbon-containing feedstock cutting unit cuts the hydrocarbon-containing feedstock into light distillate and heavy distillate, such that the weight ratio of the light distillate to the heavy distillate (light distillate / heavy distillate) is X.

[0199] In the first downward reaction unit, the light distillate oil and the first catalyst are introduced from above the reaction unit to carry out the first catalytic cracking, and the material after the first catalytic cracking is obtained below the reaction unit.

[0200] The first gas-solid separation unit introduces the material after the first catalytic cracking for gas-solid separation to obtain the first reaction oil and gas and the first catalyst to be generated.

[0201] In the second upward-flowing reaction unit, a continuous catalyst, a second catalyst stream, and the heavy distillate oil are introduced from below the reaction unit for third catalytic cracking. The product after the third catalytic cracking is obtained above the reaction unit. The continuous catalyst is at least a portion of the first catalyst to be generated. The weight ratio of the second catalyst stream to the continuous catalyst (second catalyst stream / continuous catalyst) is R.

[0202] The second gas-solid separation unit introduces the material after the third catalytic cracking for gas-solid separation to obtain the third reaction oil and gas and the third catalyst to be generated.

[0203] A separation unit is provided in which either or a mixture of the first reaction oil and gas and the third reaction oil and gas is introduced to separate low-carbon olefins and light aromatics, and to separate the light olefin fraction and return the light olefin fraction to the second upward reaction unit.

[0204] Wherein, R and X satisfy the following relationship:

[0205] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0206] T0 is the temperature (in °C) when the second catalyst enters the second upward reaction unit, and T3 is the outlet temperature (in °C) of the second upward reaction unit.

[0207] More specifically, this disclosure provides an apparatus for the catalytic cracking of hydrocarbon feedstock to produce low-carbon olefins and light aromatics, the apparatus comprising the following units:

[0208] A hydrocarbon-containing feedstock cutting unit cuts the hydrocarbon-containing feedstock into light distillate and heavy distillate, such that the weight ratio of the light distillate to the heavy distillate (light distillate / heavy distillate) is X.

[0209] In the first downward reaction unit, the light distillate oil and the first catalyst are introduced from above the reaction unit to carry out the first catalytic cracking, and the material after the first catalytic cracking is obtained below the reaction unit.

[0210] A fluidized bed reaction unit, wherein the material after the first catalytic cracking is introduced and subjected to a second catalytic cracking to obtain the material after the second catalytic cracking;

[0211] The first gas-solid separation unit introduces the material after the second catalytic cracking for gas-solid separation to obtain the second reaction oil and gas and the second catalyst to be generated.

[0212] In the second upward-flowing reaction unit, a continuous catalyst, a second catalyst stream, and the heavy distillate oil are introduced from below the reaction unit for third catalytic cracking. The product after the third catalytic cracking is obtained above the reaction unit. The continuous catalyst is at least a portion of the second catalyst to be produced, and the weight ratio of the second catalyst stream to the continuous catalyst (second catalyst stream / continuous catalyst) is R.

[0213] The second gas-solid separation unit introduces the material after the third catalytic cracking for gas-solid separation to obtain the third reaction oil and gas and the third catalyst to be generated.

[0214] A separation unit is provided in which either or a mixture of the second and third reaction gases is introduced to separate low-carbon olefins and light aromatics, and a light olefin fraction is separated and returned to the fluidized bed reaction unit.

[0215] Wherein, R and X satisfy the following relationship:

[0216] (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3)

[0217] T0 is the temperature (in °C) when the second catalyst enters the second upward reaction unit, and T3 is the outlet temperature (in °C) of the second upward reaction unit.

[0218] The apparatus disclosed herein for the catalytic cracking of hydrocarbon feedstock to produce low-carbon olefins and light aromatics is used to implement the method disclosed herein for the catalytic cracking of hydrocarbon feedstock to produce low-carbon olefins and light aromatics.

[0219] The following is for reference Figure 1 and Figure 2 The two embodiments of this disclosure will be described in detail, but this disclosure is not limited thereto.

[0220] One specific embodiment of this disclosure is as follows: Figure 1 As shown, the hot first catalyst (regenerated catalyst) is conveyed to the first downward-flowing reactor 1 through the first catalyst delivery pipe (regenerated catalyst delivery pipe) 12. Light distillate oil is injected into the first downward-flowing reactor 1 through the feed nozzle 11, contacting the first catalyst and undergoing catalytic cracking. The material after the first catalytic cracking reaction is separated from the oil and gas in the gas-solid separator 7. The resulting first reaction oil and gas is introduced into a separation device (not shown in the figure) through the oil and gas outlet of the downward-flowing reactor. The first spent catalyst is introduced into the bottom of the second upward-flowing reactor 3 as a continuous catalyst through the continuous catalyst delivery pipe 31. The second catalyst (regenerated catalyst) is introduced into the bottom of the second upward-flowing reactor 3 through the second catalyst delivery pipe (regenerated catalyst delivery pipe) 32. The catalyst after mixing the first spent catalyst (continuous catalyst) and the second catalyst is lifted upwards through a pre-lifting medium. Light olefin fraction is injected into the second upward-flowing reactor 3 through the light olefin fraction feed nozzle 21, contacting the catalyst and reacting. Heavy distillate oil is injected into the second upward reactor 3 through the heavy distillate oil feed nozzle 33 and reacts with the oil-catalyst mixture from the bottom. After the reaction, the material obtained after the third catalytic cracking enters the settling tank 4. In the settling tank 4, the third reactive catalyst and the third reaction oil gas are separated. The third reaction oil gas enters the separation device (not shown in the figure) through the oil gas outlet 41 of the third reactor. The third reactive catalyst enters the stripper 5, where the adsorbed hydrocarbon products are stripped. The third reactive catalyst is then sent to the regenerator 6 for regeneration through the conveying pipe 53. The regenerated catalyst is returned to the first downward reactor and the second upward reactor for reuse. The reaction oil gas (first reaction oil gas and third reaction oil gas) is separated by the separation device (preferably a fractionation device or a gas separation device) to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry. Low-carbon olefins and light aromatics are separated from these. In addition, a light olefin fraction is separated from the reaction oil gas and introduced into the second upward reactor 3 through the light olefin fraction feed nozzle 21.

[0221] Another specific embodiment of this disclosure is as follows: Figure 2 As shown, the hot first catalyst (regenerated catalyst) is conveyed to the first downward reactor 1 through the first catalyst delivery pipe (regenerated catalyst delivery pipe) 12. Light distillate oil is injected into the first downward reactor 1 through the feed nozzle 11, where it contacts the first catalyst and undergoes a catalytic cracking reaction. The material after the first catalytic cracking reaction is introduced into the fluidized bed reactor 2 through the mushroom head distributor 13 at the outlet of the first downward reactor. The cracking reaction continues in the fluidized bed reactor, and the second catalytic cracking material is obtained after the reaction. This material is then separated by cyclone separation to obtain the second reaction oil and gas and the second spent catalyst. The second reaction oil and gas is introduced into a separation device (not shown in the figure) through the second reaction oil and gas outlet 22. After the second spent catalyst enters the first stripper 51 to remove the adsorbed hydrocarbon products, it is introduced as a continuous catalyst into the bottom of the second upward reactor 3 through the continuous catalyst delivery pipe 31. The second catalyst (regenerated catalyst) is introduced into the bottom of the second upward reactor 3 through the second catalyst delivery pipe (regenerated catalyst delivery pipe) 32. The catalyst after the second spent catalyst (continuous catalyst) and the second catalyst are mixed is lifted upward through a pre-lifting medium. Heavy distillate oil is injected into the second upward reactor 3 through the heavy distillate oil feed nozzle 33 to react with the catalyst. After the reaction, the material obtained after the third catalytic cracking enters the settling tank 4, where the third reactive catalyst and the third reaction oil and gas are separated. The third reaction oil and gas is introduced into a separation device (not shown in the figure) through the oil and gas outlet 41 of the third reactor. The third reactive catalyst enters the second stripper 52, where the adsorbed hydrocarbon products are stripped. The third reactive catalyst is then sent to the regenerator 6 for regeneration through the third reactive catalyst conveying pipe 53. The regenerated catalyst is returned to the first downward reactor and the second upward reactor for reuse. The reaction oil and gas (second reaction oil and gas, third reaction oil and gas) is separated by a separation device (preferably a fractionation device or a gas separation device) to obtain dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry, from which low-carbon olefins and light aromatics are separated. In addition, a light olefin fraction is separated from the reaction oil and gas and returned to the fluidized bed reactor 2 through the light olefin fraction feed nozzle 21. Example

[0222] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available. The catalytic cracking catalyst used in the examples and comparative examples of this disclosure was industrially produced by the Catalyst Branch of China Petroleum & Chemical Corporation (Sinopec), with the commercial brand name DMMC-2. This catalyst contains ZSM-5 zeolite with an average pore size of less than 0.7 nm and ultrastable Y-type zeolite. Before use, the catalyst was subjected to saturated steam hydrothermal aging at 800°C for 17 hours. The main physicochemical properties of the catalyst are shown in Table 1. The hydrocarbon feedstock used in the examples and comparative examples is crude oil from Jiangsu Oilfield, and its properties are listed in Table 2.

[0223] Table 1

[0224] catalyst catalyst Physical properties <![CDATA[Specific surface area / m 2 ·g -1 > 125 <![CDATA[Pore volume / cm -3 ·g -1 > 0.197 <![CDATA[Apparent density g·cm -3 > 0.86 Chemical composition <![CDATA[Al2O3 / %]]> 56.8 <![CDATA[SiO2 / %]]> 42.9 Microreactive / % 68

[0225] Table 2

[0226] project Crude Oil A <![CDATA[Density (20 °C) / (g·cm -3 )]]> 0.849 Freezing point / °C 35 <![CDATA[Kinematic viscosity (80 °C) / (mm 2 / s)]]> 6.8 Carbon residue / % 3.5 Gum content / % 8.4 Asphalt content / % 0.2 Mass fraction of fraction below 250℃ / % 16.3 Mass fraction of fraction below 320℃ / % 28.6 Mass fraction of fraction below 350℃ / % 34.6

[0227] Example 1

[0228] In this embodiment, the cutting point of the light and heavy distillate oil of crude oil A processed is 320°C, and the cutting ratio is 0.4 (weight ratio of light distillate oil to heavy distillate oil).

[0229] The experiment was conducted using a modified medium-sized unit with a continuous reaction-regeneration operation, the process flow of which is shown in the attached figure. Figure 1As shown, a high-temperature regenerated catalyst at 720℃ is introduced into the top of the first downward-flowing reactor 1 via a regenerator through a regeneration inclined tube. Light distillate oil, preheated to 45℃, is atomized with steam and then enters the first downward-flowing reactor 1 through a feed nozzle to contact the first catalyst stream for catalytic cracking. The catalyst-to-oil ratio is 40, the reactor outlet temperature is 665℃, and the gas-solid residence time is 0.8s. The material after the first catalytic cracking is separated into first reaction oil and gas and first spent catalyst by a cyclone separator. The first reaction oil and gas enters the separation system, and all the first spent catalyst is introduced into the bottom of the second upward-flowing reactor 3. Simultaneously, a regenerated catalyst at 720℃ (the second catalyst stream) is introduced into the bottom of the second upward-flowing reactor 3 via a regenerated catalyst delivery pipe 32 from the regenerator. The weight ratio of the second catalyst to the first catalyst (second catalyst / first catalyst) is 0.25. After the first catalyst and the second catalyst are mixed at the bottom of the second upward reactor 3, the mixed catalyst flows upward under the action of pre-lifting steam. At the same time, the light olefin fraction enters the lower part of the second upward reactor 3 through the light olefin fraction feed nozzle under the atomized water vapor medium, and reacts with the mixed catalyst. The heavy distillate oil nozzle is located 800 mm above the light olefin fraction feed nozzle. After being atomized by water vapor, the heavy distillate oil is sprayed into the riser through the heavy distillate oil feed nozzle to react and undergo catalytic cracking. The catalyst-to-oil ratio is 20, the reactor outlet temperature T3 is 610℃, and the gas-solid residence time in the reactor is 1.5s. The material after catalytic cracking is introduced into a settling tank for oil-catalyst separation, which separates into third reaction oil gas and third catalyst. The third reaction oil gas is introduced into the separation system. The first reaction oil gas and the third reaction oil gas are separated into cracked gas, light gasoline, heavy gasoline, diesel, and slurry in the separation system. A portion of the light gasoline fraction (distillation range 30-60℃) is returned to the second upward reactor 3 via the light olefins feed nozzle. The third spent catalyst enters the stripper, where the hydrocarbon products adsorbed on it are stripped. The stripped catalyst then enters the regenerator through the spent catalyst inclined tube, where it is regenerated by coking at 720℃ in contact with air. The regenerated catalyst is returned to the reactor for recycling via the regeneration inclined tube. The medium-sized unit uses electric heating to maintain the temperature of the reaction-regeneration system. After the unit stabilizes (product composition remains essentially unchanged), the composition of the cracked gas and gasoline obtained from the reaction oil and gas is analyzed to obtain the yields of low-carbon olefins (hereinafter referred to as trienes) and light aromatics (hereinafter referred to as BTX) in the products.

[0230] The main operating conditions and results are listed in Table 3.

[0231] Example 2

[0232] The same apparatus and reaction steps as in Example 1 were used, except that the light and heavy component cut-off point of the crude oil A being processed was 250°C, the cut-off ratio (weight ratio of light distillate oil to heavy distillate oil) was 0.195, the weight ratio of the second catalyst to the first catalyst (second catalyst / first catalyst) was 0.03, the temperature of the regenerator was 700°C (i.e., the temperature T0 when the second catalyst enters step S4 is 700°C), and the outlet temperature T3 of the second upward reactor was 570°C.

[0233] The remaining main operating conditions and results are listed in Table 3.

[0234] Example 3

[0235] The same apparatus and reaction steps as in Example 1 were used, except that the light and heavy component cut-off point of the crude oil A being processed was 350°C, the cut-off ratio (weight ratio of light distillate oil to heavy distillate oil) was 0.529, the weight ratio of the second catalyst to the first catalyst (second catalyst / first catalyst) was 0.6, the temperature of the regenerator was 740°C (i.e., the temperature T0 when the second catalyst enters step S4 was 740°C), and the outlet temperature T3 of the second upward reactor was 630°C.

[0236] The remaining main operating conditions and results are listed in Table 3.

[0237] Example 4

[0238] The same apparatus and reaction steps as in Example 1 were used.

[0239] In this embodiment, the cutting point of the light and heavy distillate oil of crude oil A processed is 250°C, and the cutting ratio is 0.195 (weight ratio of light distillate oil to heavy distillate oil).

[0240] Except for the conditions listed in Table 3, the same conditions as in Example 1 were used.

[0241] The results are listed in Table 3.

[0242] Example 5

[0243] The same apparatus and reaction steps as in Example 1 were used.

[0244] In this embodiment, the cutting point of the light and heavy distillate oils of crude oil A processed is 350°C, and the cutting ratio (weight ratio of light distillate oil to heavy distillate oil) is 0.529.

[0245] Except for the conditions listed in Table 3, the same conditions as in Example 1 were used.

[0246] The results are listed in Table 3.

[0247] Example 6

[0248] The cut point of the processed crude oil A light and heavy distillate oil is 320℃, and the cut ratio (weight ratio of light distillate oil to heavy distillate oil) is 0.4.

[0249] The experiment was conducted using a modified medium-sized unit with a continuous reaction-regeneration operation, the process flow of which is shown in the attached figure. Figure 2 As shown, a high-temperature regenerated catalyst at 720℃ is introduced into the top of the first downward-flowing reactor 1 via a regenerator through a regeneration inclined tube. Light distillate oil, preheated to 45℃, is atomized with steam and enters the first downward-flowing reactor 1 through a feed nozzle, where it contacts the first stream of catalyst for catalytic cracking. The catalyst-to-oil ratio is 40, the reactor outlet temperature is 670℃, and the gas-solid residence time is 0.6 s. The material after the first catalytic cracking enters the fluidized bed reactor 2 through an outlet distributor for further catalytic cracking at a reaction temperature of 655℃ and a mass hourly space velocity (HHSV) of 4 h⁻¹. -1 Additionally, the light olefin fraction, after being atomized with steam, enters the bottom of the fluidized bed reactor 2 through the feed nozzle 21, where it reacts with the hot catalyst. The material after the second catalytic cracking is then separated by cyclone separation to obtain the second reaction oil and gas and the second spent catalyst. The second reaction oil and gas is introduced into the subsequent separation system, and the separated second spent catalyst is stripped and then introduced entirely into the bottom of the second upward reactor 3. Simultaneously, the regenerated catalyst (the second stream of catalyst) at a temperature of 720°C is introduced into the bottom of the second upward reactor 3 via the regenerated catalyst delivery pipe 32 from the regenerator. The weight ratio of the second catalyst to the second spent catalyst (second catalyst / second spent catalyst) is 0.25. After the second spent catalyst and the second catalyst are mixed at the bottom of the second upward reactor 3, the mixed catalyst flows upward under the action of pre-lifting steam. The heavy distillate oil is atomized by water vapor and sprayed into the second upward reactor 3 through the heavy distillate oil nozzle, where it contacts the catalyst and undergoes a catalytic cracking reaction. The catalyst-to-oil ratio is 20, the reactor outlet temperature T3 is 610℃, and the gas-solid residence time in the reactor is 1.5s. The material after catalytic cracking is introduced into a settling tank for oil-catalyst separation, separating into third reaction oil gas and third spent catalyst. The reaction oil gas is introduced into the separation system. The second and third reaction oil gas are separated into cracked gas, light gasoline, heavy gasoline, diesel, and slurry in the separation system. A portion of the light gasoline fraction (distillation range 30-60℃) is returned to the fluidized bed reactor 2 as light olefin fraction. The third-generation catalyst enters the stripper, where it strips off the hydrocarbon products adsorbed by the catalyst. The stripped catalyst then enters the regenerator through a regenerator tube, where it is regenerated by coking with air at 720°C. The regenerated catalyst is returned to the reactor for recycling via a regeneration tube. The medium-sized unit uses electric heating to maintain the temperature of the reaction and regeneration systems. Once the unit is running stably (with the product composition remaining essentially unchanged), the composition of the cracked gas and gasoline obtained from the reaction oil and gas is analyzed to determine the yields of trienes and BTX in the products.

[0250] The main operating conditions and results are listed in Table 3.

[0251] Example 7

[0252] The same apparatus and reaction steps as in Example 6 were used, except that the light and heavy component cut-off point of the crude oil A being processed was 250°C, the cut-off ratio (weight ratio of light distillate oil to heavy distillate oil) was 0.195, the weight ratio of the second catalyst to the second spent catalyst (second catalyst / second spent catalyst) was 0.03, the temperature of the regenerator was 700°C (i.e., the temperature T0 when the second catalyst enters step S4 is 700°C), and the outlet temperature T3 of the second upward reactor was 570°C.

[0253] The remaining main operating conditions and results are listed in Table 3.

[0254] Example 8

[0255] The same apparatus and reaction steps as in Example 6 were used, except that the light and heavy component cut-off point of the crude oil A being processed was 350°C, the cut-off ratio (weight ratio of light distillate oil to heavy distillate oil) was 0.529, the weight ratio of the second catalyst to the second spent catalyst (second catalyst / second spent catalyst) was 0.6, the temperature of the regenerator was 740°C (i.e., the temperature T0 when the second catalyst enters step S4 is 740°C), and the outlet temperature T3 of the second upward reactor was 630°C.

[0256] The remaining main operating conditions and results are listed in Table 3.

[0257] Comparative Example 1

[0258] The same apparatus, reaction steps, and reaction conditions as in Example 1 were used, except that the light olefin fraction separated from the reaction oil and gas was not refluxed to the second upward reactor 3.

[0259] The remaining main operating conditions and results are listed in Table 3.

[0260] Comparative Example 2

[0261] The same apparatus and reaction steps as in Example 1 were used, except that the weight ratio of the second catalyst to the first catalyst (second catalyst / first catalyst) was 0.1, the temperature of the regenerator was 740°C (i.e., the temperature T0 when the second catalyst enters step S4 was 740°C), and the outlet temperature T3 of the second upward reactor was 610°C.

[0262] The remaining main operating conditions and results are listed in Table 3.

[0263] Comparative Example 3

[0264] The same apparatus and reaction steps as in Example 1 were used, except that the weight ratio of the second catalyst to the first catalyst (second catalyst / first catalyst) was 0.5, the temperature of the regenerator was 700°C (i.e., the temperature T0 when the second catalyst enters step S4 was 700°C), and the outlet temperature T3 of the second upward reactor was 610°C.

[0265] The remaining main operating conditions and results are listed in Table 3.

[0266] Comparative Example 4

[0267] The same apparatus, reaction steps, and reaction conditions as in Example 1 were used, except that a second catalyst was not introduced into the lower part of the second upward reactor 3, and only the first catalyst was used.

[0268] The remaining main operating conditions and results are listed in Table 3.

[0269] Comparative Example 5

[0270] The same apparatus, reaction steps, and reaction conditions as in Example 1 were used, except that the first catalyst was not introduced into the lower part of the second upward reactor 3, and only the second catalyst was used.

[0271] The remaining main operating conditions and results are listed in Table 3.

[0272] Comparative Example 6

[0273] The same apparatus, reaction steps, and reaction conditions as in Example 1 were used, except that the light distillate oil entered the second upward reactor, that is, the first downward reactor 1 became the second upward reactor (the parameters of the first downward reactor in Table 3 represent the parameters of the upward tubular reactor in Comparative Example 6).

[0274] The remaining main operating conditions and results are listed in Table 3.

[0275]

[0276]

[0277] As can be seen from the data in Table 3, the method for producing low-carbon olefins and BTX by catalytic cracking of hydrocarbon feedstock provided in this disclosure can significantly improve the yield of low-carbon olefins and light aromatics, while suppressing the yield of by-products such as dry gas and coke.

[0278] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0279] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0280] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for producing low-carbon olefins and light aromatics by catalytic cracking of hydrocarbon feedstock oil, the method comprising the following steps: S1. The hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil, wherein the weight ratio of the light distillate oil to the heavy distillate oil is X; S2. The light distillate oil and the first catalyst are introduced into the first downward reactor to carry out the first catalytic cracking to obtain the material after the first catalytic cracking. S3. Perform gas-solid separation on the material after the first catalytic cracking to obtain the first reaction oil and gas and the first catalyst to be generated; S4. The continuous catalyst, the heavy distillate oil, and the second catalyst are introduced into the second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain third reaction oil and gas and third catalyst to be generated; the continuous catalyst is at least a portion of the first catalyst to be generated; the weight ratio of the second catalyst to the continuous catalyst is R. S5. Separate low-carbon olefins and light aromatics from either the first reactant gas and the third reactant gas, or a mixture of the first reactant gas and the third reactant gas, and separate the light olefin fraction, returning the light olefin fraction to the second upward reactor in step S4. R and X satisfy the following relationship: (4.84×T0-3340) / (780+5×T0-6×T3) <R / X<(0.968×T0-630) / (668+0.2×T0-1.2×T3) T0 is the temperature at which the second catalyst enters step S4, in °C, and T3 is the outlet temperature of the second upward reactor, in °C.

2. The method according to claim 1, wherein, The outlet temperature T3 of the second upward reactor is 530-650℃; and / or The temperature T0 when the second catalyst enters step S4 is 690-750℃.

3. The method according to claim 1 or 2, wherein, In step S1, the hydrocarbon-containing feedstock oil is cut into light distillate oil and heavy distillate oil at any temperature between 100-400℃, such that the weight ratio of the light distillate oil to the heavy distillate oil is X.

4. The method according to claim 1 or 2, wherein, In the first downward-flowing reactor, the conditions for the first catalytic cracking include: an outlet temperature of 610-720°C, a gas-solid residence time of 0.1-3.0 seconds, and a catalyst-to-oil ratio of 15-80; and / or In the second upward reactor, the conditions for the third catalytic cracking include: a gas-solid residence time of 0.5-8 seconds and a catalyst-to-oil ratio of 8-40.

5. The method according to claim 1 or 2, wherein, In the first downward-flowing reactor, the conditions for the first catalytic cracking include: an outlet temperature of 650-690°C, a gas-solid residence time of 0.5-1.5 seconds, and a catalyst-to-oil ratio of 25-65; and / or In the second upward reactor, the conditions for the third catalytic cracking include: a gas-solid residence time of 1.5-5 seconds and an agent-to-oil ratio of 10-30.

6. The method according to claim 1 or 2, wherein, In step S4, the continuous catalyst is first mixed with the second catalyst stream, and then the subsequent catalytic cracking reaction is carried out; and / or In step S4, the light olefin fraction from step S5 is contacted with the mixture of the second catalyst and the continuous catalyst before the heavy distillate oil; and / or The method has a step S0 before step S1, wherein the hydrocarbon-containing feedstock oil is desalted and dehydrated, and the resulting dehydrated and desalted hydrocarbon-containing feedstock oil is introduced into step S1 for cutting.

7. The method according to claim 1 or 2, wherein, The method also includes: In the gas-solid separation of step S4, the separated catalyst is stripped to obtain a third catalyst to be produced; and / or The third spent catalyst and the first spent catalyst that did not enter the second upward reactor are subjected to coke regeneration at a temperature of 690-750°C to obtain a regenerated catalyst; and / or Separating either the first reacted oil and gas or the third reacted oil and gas, or a mixture thereof, yields dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry oil. Low-carbon olefins and light aromatics are separated from these components, and a light olefin fraction is also separated. In step S5, a light olefin fraction is separated from either the first reaction oil and gas, the third reaction oil and gas, or a mixture of both, and the light olefin fraction is returned to the second upward reactor in step S4.

8. The method according to claim 1 or 2, wherein, The hydrocarbon-containing feedstock is one or a mixture of two or more of crude oil, coal liquefaction oil, synthetic oil, oil sands oil, shale oil, tight oil, and animal and vegetable oils, or a portion of their respective distillates or their respective heavy distillates, which are hydrotreated and upgraded.

9. The method according to claim 1 or 2, wherein, The first catalyst and the second catalyst each independently include an active component and a support. The active component is selected from at least one of ultrastable Y-type zeolite with or without rare earth elements, ZSM-5 series zeolite, high-silica zeolite with a five-membered ring structure, and β-zeolite. The support is selected from at least one of alumina, silicon oxide, amorphous aluminum silicate, zirconium oxide, titanium oxide, boron oxide, and alkaline earth metal oxides.

10. The method according to claim 1 or 2, wherein, The first and second catalyst streams each independently include a regenerated catalyst, and / or The entirety of the first catalyst to be produced is used as a continuous catalyst.

11. The method according to claim 1, wherein, After step S2, step S2' is performed, in which the material after the first catalytic cracking is introduced into a fluidized bed reactor for second catalytic cracking to obtain the material after the second catalytic cracking. In step S3, the material after the second catalytic cracking is subjected to gas-solid separation to obtain the second reaction oil and gas and the second catalyst to be generated; In step S4, the continuous catalyst, the heavy distillate oil, and the second catalyst are introduced into the second upward reactor for third catalytic cracking, followed by gas-solid separation to obtain the third reaction oil and gas and the third catalyst to be generated; the continuous catalyst is at least a part of the second catalyst to be generated. In step S5, low-carbon olefins and light aromatics are separated from either the second reaction oil and gas or the third reaction oil and gas or a mixture thereof, and a light olefin fraction is separated and returned to the second upward reactor in step S4 or to the fluidized bed reactor in step S2'.

12. The method according to claim 11, wherein, In the fluidized bed reactor, the conditions for the second catalytic cracking include: a reaction temperature of 600-690℃ and a mass hourly space velocity of 2-20 h⁻¹. -1 ; and / or In step S2', during the gas-solid separation in step S3, the separated catalyst is stripped to obtain a second catalyst to be produced; and / or The entirety of the second catalyst to be generated is used as a continuous catalyst; and / or Separating either the second or third reacted oil and gas, or a mixture thereof, yields dry gas, C3 fraction, C4 fraction, light gasoline, heavy gasoline, diesel, and slurry oil. Low-carbon olefins and light aromatics are separated from these fractions, along with a light olefin fraction; and / or In step S5, a light olefin fraction is separated from either the second or third reaction oil / gas, or a mixture of both, and the light olefin fraction is returned to the fluidized bed reactor of step S2'; and / or The third spent catalyst and the second spent catalyst that did not enter the second upward reactor were coked and regenerated at a temperature of 690-750°C to obtain a regenerated catalyst.

13. The method according to claim 11 or 12, wherein, In the fluidized bed reactor, the conditions for the second catalytic cracking include: a reaction temperature of 640-670°C and a mass hourly space velocity (HHSV) of 4-12 h⁻¹. -1 .

14. The method according to claim 1 or 2, wherein, At least one of the following conditions must be met: The outlet temperature T3 of the second upward reactor is 600-630℃; and / or The temperature T0 when the second catalyst enters step S4 is 710-725℃; and / or In step S4, the light olefin fraction is contacted with the mixture of the second catalyst and the continuous catalyst 0.4-0.8 seconds before the heavy distillate oil; and / or The third unregenerated catalyst is regenerated by coking at a temperature of 710-725°C to obtain a regenerated catalyst; and / or The first and second catalyst streams are regenerated catalysts.

15. The method according to claim 1 or 2, wherein, The third spent catalyst and the first spent catalyst that did not enter the second upward reactor were coked and regenerated at a temperature of 710-725°C to obtain a regenerated catalyst.

16. The method according to claim 11 or 12, wherein, The third spent catalyst and the second spent catalyst that did not enter the second upward reactor were coked and regenerated at a temperature of 710-725°C to obtain a regenerated catalyst.

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