Method and system for direct catalytic cracking of inferior crude oil

Abstract

The invention relates to a method and system for direct catalytic cracking of inferior crude oil, and the method comprises the following steps: carrying out catalytic cracking reaction on the crude oil in a first reactor, carrying out catalytic cracking reaction on components difficult to convert in a second reactor, carrying out gas-solid separation on a reaction product and a spent catalyst, and carrying out steam stripping and scorching regeneration on the spent catalyst to obtain the inferior crude oil. Part of the regenerated catalyst is returned to the first reactor for recycling, and part of the regenerated catalyst is returned to the second reactor for recycling after being subjected to reduction activation; and separating the reaction product to obtain ethylene, propylene, a difficult-to-convert component and other products, wherein the difficult-to-convert component enters the second reactor to be further subjected to catalytic cracking reaction to obtain ethylene and propylene. When the catalytic cracking method and system are used for the catalytic cracking reaction of crude oil, chemical raw materials such as ethylene and propylene can be produced with high selectivity, and efficient utilization of crude oil resources is realized.

Description

Technical Field

[0001] The present application relates to the field of petrochemical industry, and in particular, to a method and system for direct catalytic cracking of inferior crude oil. Background Art

[0002] Ethylene, propylene and BTX (benzene-toluene-xylene) are key basic organic synthetic raw materials with huge demand. They can be used to produce a variety of organic chemical products, including many important high-end organic chemical products. They are closely related to people's food, clothing, housing and transportation, and are an important guarantee for the country's high-quality and sustainable development. The existing technical route for producing propylene and BTX from petroleum is developed on the basis of the traditional petroleum refining process that mainly produces oil products. There are problems such as long production process, low chemical yield and insignificant economic benefits. The technical measures to solve this problem are to develop key core technologies that mainly produce chemicals and can direct the conversion of crude oil hydrocarbon molecules into chemicals. Therefore, in recent years, petrochemical companies at home and abroad have been actively exploring the technical route of directly producing chemicals from crude oil, so as to make the processing path from crude oil to low-carbon olefins and BTX and other chemicals shorter, with lower energy consumption and smaller investment.

[0003] WO2005113722A3 and CN200780047937.2 disclose a process for producing crude oil directly into chemicals, wherein the crude oil directly enters a steam cracking furnace, and is flash evaporated to separate light components and heavy components, the light components (gaseous components) enter the steam cracking furnace for cracking, and the heavy components (liquid components) are used as refinery raw materials.

[0004] CN 201380015214.X discloses a process for producing olefins and aromatics from crude oil by integrating hydroprocessing, steam cracking and catalytic cracking processes. After the crude oil is hydroprocessed, impurities such as sulfur and high-boiling substances are removed, and the hydrogenated products are separated by distillation. The light components enter the steam cracking unit, and the heavy components are subjected to the catalytic cracking unit to maximize the production of olefins.

[0005] CN201780078199.1 discloses a method and system for converting crude oil into petrochemicals and fuel products by integrating steam cracking and fluid catalytic cracking. Crude oil is separated into straight-run naphtha and lighter component fractions, one or more intermediate distillate fractions, and atmospheric residue fractions. Vacuum distillate oil is then separated from the atmospheric residue fraction as a catalytic cracking feedstock. The light fraction is hydrogenated and used as naphtha and diesel fuel oil.

[0006] The above crude oil processing routes all use steam cracking as the main technical means to produce light olefins. Due to the high energy consumption of steam cracking technology and the poor flexibility of product solutions, researchers are also actively developing technical solutions for producing light olefins by catalytic cracking.

[0007] The method for preparing low-carbon olefins and aromatics by catalytic cracking of crude oil disclosed in CN20181189551.1 and CN201811190135.3 comprises the following steps: after desalting and dehydrating the crude oil, the crude oil is divided into light and heavy components, and the light component, i.e., light feed, and the heavy component, i.e., heavy feed, are respectively placed in two catalytic cracking reactors, and are contacted with a high-temperature catalyst under a steam atmosphere to react to produce low-carbon olefins and aromatics. Alternatively, the light component and the heavy component react in different reaction zones of the same reactor.

[0008] CN 201810523356.1 discloses a method for processing a whole fraction of crude oil. The method separates the whole fraction of crude oil to obtain light distillate oil, middle distillate oil and heavy distillate oil. The middle distillate oil and the heavy distillate oil are reacted in a first riser, and the light distillate oil is reacted in a fluidized bed reactor connected in series with the riser. The reaction conditions in the reactor vary according to the properties of the raw materials.

[0009] Existing crude oil catalytic cracking technologies all use crude oil distillation to separate fractions, and then catalytic cracking reactions, that is, light fractions and heavy fractions enter their respective reaction zones or reactors for catalytic cracking reactions. Different catalytic cracking reaction environments are selected according to the performance differences of different fractions, which is beneficial to improving the conversion rate of crude oil molecular cracking reactions to a certain extent. However, the process of crude oil flash evaporation is still not avoided, and the real direct catalytic cracking technology route of crude oil has not been realized. In addition, when the quality of crude oil deteriorates, such as intermediate base crude oil, its heavy fraction has a large density and is not easy to gasify. The catalytic reaction selectivity is poor during the reaction, and the coke yield is high. Summary of the invention

[0010] The purpose of this application is to provide a method and system for catalytic cracking of crude oil into chemical raw materials such as light olefins and aromatics based on the current catalytic cracking technology, which will help to improve the yield and selectivity of chemical raw materials and achieve efficient utilization of crude oil resources.

[0011] A first aspect of the present invention provides a method for direct catalytic cracking of inferior crude oil, the method comprising:

[0012] (1) A first feedstock and a regenerated catalyst from a regenerator enter a first reactor for a catalytic cracking reaction, and optionally, the reaction product contacts an introduced supplemental catalyst and continues to react;

[0013] (2) the second raw material is introduced from the downstream feed section of the second reactor, and is contacted with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction, wherein the catalyst mixture includes a regenerated catalyst and a fresh catalyst;

[0014] (3) The reaction products of the first reactor and the second reactor and the catalyst to be produced enter the oil separation device for gas-solid separation, and the separated reaction oil and gas are led out of the device for further separation to obtain ethylene, propylene, difficult-to-convert components and other products;

[0015] (4) the separated catalyst to be regenerated enters the regenerator for oxygen-containing regeneration after stripping, the first part of the regenerated catalyst returns to the first reactor for reaction circulation, the second part of the regenerated catalyst enters the catalyst reducer for reduction reaction and releases energy under the action of the reducing medium, and the regenerated catalyst after reduction enters the second reactor for reaction circulation;

[0016] Wherein, the first raw material is low-quality crude oil, and the low-quality crude oil is selected from one or more of intermediate base crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate base crude oil;

[0017] The second raw material is produced by the device itself and / or other difficult-to-convert components, and the difficult-to-convert components are C4 components and / or light distillate oil with a final boiling point of less than 260-300°C.

[0018] According to the method of the first aspect, the properties of the inferior crude oil meet at least one of the following indicators: the characteristic factor K value is not less than 11.5; the relative density is not more than 935 kg / m 3 ; The residual carbon is not more than 10% by weight; The total content of nickel and vanadium is not more than 50 mg / kg.

[0019] The method according to the first aspect, wherein the difficult-to-convert components include the C4 fraction produced by the device and the gaseous hydrocarbons rich in the C4 fraction produced by other devices, wherein the content of C4 olefins in the gaseous hydrocarbons rich in the C4 fraction is greater than 50% by weight;

[0020] Preferably, the difficult-to-convert component is the C4 fraction produced by the device.

[0021] The method according to the first aspect, wherein the difficult-to-convert components include light distillate oil produced by the device with a final boiling point of less than 260-300°C and one or more of the following fractions: straight-run naphtha, straight-run kerosene, and straight-run diesel produced by other primary processing devices; topped oil, raffinate oil, hydrocracking light naphtha, pentane oil, coker gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrogenated gasoline, and hydrogenated diesel produced by other secondary processing devices.

[0022] The method according to the first aspect, wherein the catalytic cracking reaction temperature in the first reactor is 510-650°C, and the weight hourly space velocity is 1-20 hours -1 The weight ratio of catalyst to oil is (3-50):1, and the catalyst density is 120-290 kg / m 3, and / or the reaction pressure is 130-450 kPa;

[0023] Preferably, the first raw material enters the first reactor after being preheated and steam atomized, the preheating temperature is 180-350° C., and the water-oil weight ratio is (0.03-0.5):1.

[0024] The method according to the first aspect, wherein the supplementary catalyst accounts for 0-30 wt % of the total circulating amount of the catalyst in the first reactor.

[0025] The method according to the first aspect, wherein the second reactor is provided with a main reaction section and one or more difficult-to-convert component feed sections;

[0026] Preferably, the one or more difficult-to-convert component feed sections are each independently arranged in the middle and upstream of the second reactor;

[0027] Preferably, the catalyst density in the difficult-to-convert component feed section is 120-290 kg / m 3 ; and / or

[0028] Preferably, the ratio of the diameter of the difficult-to-convert component feed section to the diameter of the main reaction section is (1.2-1.5):1.

[0029] The method according to the first aspect, wherein the catalytic cracking reaction temperature in the second reactor is 580-750°C, the reaction time is 0.05-5 seconds, the catalyst-oil weight ratio is (1-50):1, and the catalyst density is 20-100 kg / m 3 , and / or the reaction pressure is 130-450 kPa;

[0030] Preferably, the second raw material is introduced into the second reactor after being steam atomized, and the water-oil weight ratio is (0.03-0.5):1.

[0031] The method according to the first aspect, wherein the weight ratio of the fresh catalyst to the regenerated catalyst in the catalyst reducer is (0.005-0.3):1.

[0032] According to the method of the first aspect, the reduction temperature in the catalyst reducer is 550-750°C,

[0033] The recovery time is 2-20 minutes; and / or

[0034] The reducing medium is refinery dry gas and / or small molecule alkane, wherein the small molecule alkane is C1-C3 alkane, preferably refinery dry gas.

[0035] The method according to the first aspect, wherein the regeneration temperature in the regenerator is 550-750°C, preferably 600-730°C, more preferably 650-720°C;

[0036] The gas superficial velocity is 0.5-3 m / s, preferably 0.8-2.5 m / s, more preferably 1-2 m / s;

[0037] The average residence time of the spent catalyst is 0.6-3 minutes, preferably 0.8-2.5 minutes, more preferably 1-2 minutes.

[0038] The method according to the first aspect, wherein the catalyst comprises 0.01-5wt%, preferably 0.005-2wt% of metal oxide based on the dry weight of the catalyst, and the metal in the metal oxide is selected from one or more of the following: tin, cobalt, iron, molybdenum, manganese, copper, barium and chromium;

[0039] Preferably, the catalyst comprises:

[0040] 0-70 parts by weight, preferably 5-60 parts by weight, more preferably 10-50 parts by weight of clay,

[0041] 5-99 parts by weight, preferably 10-80 parts by weight, more preferably 20-70 parts by weight of a binder,

[0042] 1-60 parts by weight, preferably 5-45 parts by weight, more preferably 10-40 parts by weight of zeolite, and

[0043] 0.001-5 parts by weight, preferably 0.005-2 parts by weight of a metal oxide,

[0044] The total weight of the catalyst is 100 parts by weight;

[0045] Wherein, the binder is an inorganic oxide binder, preferably silicon dioxide and / or aluminum oxide;

[0046] The zeolite comprises a medium-pore zeolite and an optional large-pore zeolite, wherein the medium-pore zeolite is a ZSM series zeolite and / or a ZRP zeolite, and the large-pore zeolite is one or more selected from rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultrastable Y-type zeolite and high-silicon Y-type zeolite. Preferably, the medium-pore zeolite accounts for 5-100% by weight, preferably 50-90% by weight, and more preferably 20-50% by weight of the total weight of the zeolite;

[0047] The clay is preferably kaolin and / or halloysite.

[0048] A second aspect of the present invention provides a catalytic cracking system, comprising:

[0049] The catalytic cracking reaction unit comprises:

[0050] The first reactor is provided with a pre-lifting medium inlet, a regenerated catalyst inlet, a supplementary catalyst inlet, a feedstock oil inlet and a first oil-agent mixture outlet;

[0051] The second reactor is provided with a pre-lifting section, a feed section, a main reaction section and an outlet section in order from bottom to top, wherein a reduction catalyst inlet and a pre-lifting medium inlet are provided at the bottom of the pre-lifting section, and a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional catalyst outlet are provided in the feed section;

[0052] an oil-agent separation device, the oil-agent separation device being connected to both the first oil-agent mixture outlet of the first reactor and the second oil-agent mixture outlet of the second reactor, so that the first oil-agent mixture from the first reactor and the second oil-agent mixture from the second reactor are separated into reaction oil gas and catalyst to be generated by the oil-agent separation device; and

[0053] A settler, used for settling and collecting the spent catalyst separated by the oil agent separation device, a stripping section is provided below the settler for stripping the spent catalyst, and the stripping section is provided with a spent catalyst outlet and a stripping medium inlet;

[0054] A reaction product separation unit, the reaction product separation unit is connected to the oil agent separation device and is used to separate the reaction oil gas separated by the oil agent separation device;

[0055] A regenerator, wherein the regenerator is provided with an inlet for regenerated catalyst, an inlet for oxygen-containing gas, a gas distributor, a cyclone separator, a regenerated flue gas pipeline and at least one regenerated catalyst outlet; the inlet for regenerated catalyst of the regenerator is fluidly connected to the outlet for regenerated catalyst of the stripping section; one regenerated catalyst outlet is connected to the inlet for regenerated catalyst of the first reactor, for recycling a part of the regenerated catalyst back to the first reactor; and

[0056] A catalyst reducer, wherein the catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a reduced catalyst outlet and a reducing medium inlet; the regenerated catalyst inlet of the catalyst reducer is connected with a regenerated catalyst outlet, so that a part of the regenerated catalyst from the regenerator is reduced in the catalyst reducer; the reduced catalyst outlet of the catalyst reducer is fluidly connected with the reduced catalyst inlet of the second reactor, so that the reduced catalyst is circulated back to the second reactor.

[0057] According to the catalytic cracking system of the second aspect, wherein the first reactor is provided with one or more supplementary catalyst inlets;

[0058] Preferably, the one or more supplemental catalyst inlets are each independently located at a height greater than 0% to 90% of the total height of the first reactor, preferably at a height of 20% to 80% of the total height of the first reactor, and more preferably at a height of 30% to 75% of the total height of the first reactor.

[0059] According to the catalytic cracking system of the second aspect, the second reactor comprises two feed sections connected in sequence, the first feed section is connected to the pre-lifting section, the second feed section is connected to the main reaction section, and an external catalyst circulation pipeline connecting the two feed sections is provided between the first feed section and the second feed section;

[0060] Preferably, the distance between the connection port of the external catalyst circulation pipe on the first feed section and the bottom of the first feed section is 0 to 10% of the height of the second feed section; and / or the distance between the catalyst outlet on the second feed section and the bottom of the second feed section is 5% to 20% of the height of the second feed section.

[0061] Compared with the prior art, the method and system of the present invention have the following beneficial effects:

[0062] 1) It can realize direct catalytic cracking of inferior crude oil, reduce the crude oil distillation process, simplify the process and reduce operating costs.

[0063] 2) In the process of catalytic cracking of crude oil, the single-pass conversion rate is not pursued. The light distillate oil that is difficult to convert is recycled. By setting up specific reaction zones, a higher overall conversion rate and higher target product selectivity can be achieved.

[0064] 3) According to the reaction performance of the difficult-to-convert component, it is introduced into the reactor in a specific feed section of the second reactor. The higher catalyst density and higher catalyst activity in the feed section are conducive to improving the reaction conversion rate and catalytic reaction selectivity of the difficult-to-convert component.

[0065] 4) The catalyst in the second feed section can be selectively returned to the first feed section to improve the catalyst-oil ratio of the first feed section, and can also be selectively removed from the reactor according to the degree of carbonization of the catalyst, which helps to improve the catalyst activity in the reactor.

[0066] 5) A regenerated catalyst reducer is provided. The catalyst contains a variable-valence metal. Energy is stored and released through the gain and loss of electrons or the shift of common electron pairs between the metal and the metal oxide, providing heat for the catalytic cracking reaction of the difficult-to-convert components, thereby solving the problem of high heat demand for the reaction of the difficult-to-convert components.

[0067] By adopting the catalytic cracking method of the present application, chemical raw materials such as ethylene and propylene can be efficiently produced directly from crude oil, achieving efficient utilization of crude oil resources, alleviating the situation of excess refined oil, and helping refineries to transform, develop and extend from oil refining to chemical raw material production, reducing production costs and increasing refineries' profit margins. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present application but do not constitute a limitation to the present application. In the accompanying drawings:

[0069] Figure 1 A schematic diagram of a process for producing light olefins and aromatics by catalytic cracking of inferior crude oil according to an embodiment of the present application.

[0070] Description of reference numerals:

[0071] 100, first reactor; 101, first pre-lift medium pipeline; 102, first reactor feed pipeline; 103, catalyst supplement pipeline; 104, first reactor outlet section; 200, settler; 201, lower part of the settler stripping section; 202, gas medium pipeline; 203, waiting inclined pipe; 204, oil agent separation device; 205, gas collecting chamber; 206, large oil and gas pipeline; 300, second reactor; 301, second pre-lift medium pipeline; 303, second reactor first feed pipeline; 304, second reactor second feed pipeline; 305, second reactor third feed pipeline; 306, second reactor External catalyst circulation pipeline; 307, catalyst outlet; 308, second reactor outlet section; 309, second reactor pre-lift section; 310, second reactor main reaction section; 311, second reactor first feed section; 312, second reactor second feed section; 400, regenerator; 401, oxygen-containing gas inlet; 402, gas distributor; 403, first regeneration inclined pipe; 404, cyclone separator; 405, regeneration flue gas recovery pipeline; 406, second regeneration inclined pipe; 500, catalyst reducer; 501, reducing medium pipeline; 503, reduced catalyst inclined pipe; 504, fresh catalyst pipeline. DETAILED DESCRIPTION

[0072] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0073] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0074] Any specific numerical value (including the endpoint of the numerical range) disclosed in this application is not limited to the exact value of the numerical value, but should be understood to also cover values ​​close to the exact value, such as all possible values ​​within the range of ±5% of the exact value. In addition, for the disclosed numerical range, the endpoint values ​​of the range, the endpoint values ​​and the specific point values ​​in the range, and the specific point values ​​can be arbitrarily combined to obtain one or more new numerical ranges, and these new numerical ranges should also be regarded as specifically disclosed herein.

[0075] In the present application, the terms "upstream" and "downstream" are based on the flow direction of the reactants. For example, when the reactants flow from bottom to top, "upstream" means the position below, while "downstream" means the position above.

[0076] In this article, low-carbon olefins are a general term for ethylene, propylene and butene, and light aromatics (BTX) are a general term for benzene (BTX), toluene (T) and xylene (X).

[0077] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition herein shall prevail.

[0078] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0079] The present invention provides a method for direct catalytic cracking of inferior crude oil, the method comprising:

[0080] (1) A first feedstock and a regenerated catalyst from a regenerator enter a first reactor for a catalytic cracking reaction, and optionally, the reaction product contacts an introduced supplemental catalyst and continues to react;

[0081] (2) the second raw material is introduced from the downstream feed section of the second reactor, and is contacted with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction, wherein the catalyst mixture includes a regenerated catalyst and a fresh catalyst;

[0082] (3) The reaction products of the first reactor and the second reactor and the catalyst to be produced enter the oil separation device for gas-solid separation, and the separated reaction oil and gas are led out of the device for further separation to obtain ethylene, propylene, difficult-to-convert components and other products;

[0083] (4) the separated catalyst to be regenerated enters the regenerator for oxygen-containing regeneration after stripping, the first part of the regenerated catalyst returns to the first reactor for reaction circulation, the second part of the regenerated catalyst enters the catalyst reducer for reduction reaction and releases energy under the action of the reducing medium, and the regenerated catalyst after reduction enters the second reactor for reaction circulation;

[0084] Wherein, the first raw material is low-quality crude oil, and the low-quality crude oil is selected from one or more of intermediate base crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate base crude oil;

[0085] The second raw material is produced by the device itself and / or other difficult-to-convert components, and the difficult-to-convert components are C4 components and / or light distillate oil with a final boiling point of less than 260-300°C.

[0086] The present application will be further described below with reference to the preferred implementation modes shown in the accompanying drawings, but the present application is not limited thereby.

[0087] Figure 1 A preferred embodiment of the catalytic cracking method of low-quality crude oil of the present application is provided, wherein the catalytic cracking reactor comprises a first reactor 100 and a second reactor 300. The second reactor 300 is provided with a pre-lifting section 309, a first feed section 311, a second feed section 312, a main reaction section 310 and an outlet section 308.

[0088] The pre-lifting medium enters the bottom of the first reactor 100 through the first pre-lifting medium pipeline 101. The lifting medium can be dry gas, water vapor or a mixture thereof, which is mixed with the hot regenerated catalyst from the first regeneration inclined tube 403 and moves upward. The reaction raw materials such as preheated crude oil and atomized steam are injected into the lower part of the first reactor 100 through the first reactor feed pipeline 102, mixed with the high-temperature regenerated catalyst and subjected to catalytic cracking reaction. The first reactor is also provided with a supplementary catalyst pipeline 103 for supplementing the catalyst.

[0089] The hot regenerated catalyst from the second regeneration inclined tube 406 and the fresh catalyst from the fresh catalyst pipeline 504 enter the reducer 500. Under the action of the reducing medium introduced through the reducing medium pipeline 501, the metal oxide reduction reaction on the catalyst occurs, releasing energy. The high-temperature regenerated catalyst enters the bottom of the second reactor through the reducing catalyst inclined tube 503, moves upward under the lifting action of the pre-lifting medium from the second pre-lifting medium pipeline 301, and the pre-lifting medium can be steam or refinery dry gas, and enters the first feed section of the second reactor;

[0090] The difficult-to-convert raw material and the atomized steam are injected into the lower part of the first feed section 311 of the second reactor through the first feed line 303 of the second reactor, and are mixed and contacted with the existing catalyst in the catalytic cracking reactor. The oil-agent mixture moves upward, and optionally, is mixed with part of the difficult-to-convert group injected through the second feed line 304 of the second reactor and the third feed line 305 of the second reactor and enters the upstream of the second feed section 312. Optionally, part of the difficult-to-convert raw material enters the downstream of the second feed section 312 through the pipeline 305, and the oil-agent mixture enters the main reaction section 310, and the cracking reaction occurs fully. The catalyst-to-oil ratio and activity of the catalyst in the first feed section 311 and the second feed section 312 can be adjusted according to the reaction requirements by adjusting the flow of the external catalyst circulation pipeline 306 and the catalyst outlet pipeline 307. The reaction oil gas and the catalyst to be generated by the catalytic cracking reaction of the first reactor and the second reactor flow upward respectively through the first reactor outlet section 104 and the second reactor outlet section 308 to enter the oil-agent separation device 204 such as a cyclone separator for gas-solid separation. The reaction oil and gas obtained by separation are led out of the gas collecting chamber 205 and the large oil and gas pipe 206 and enter the subsequent separation system; the catalyst to be regenerated obtained by separation enters the lower stripping section 201 of the settler 200, and after being stripped by the stripping medium from the stripping medium pipeline 202, it enters the regenerator 400 through the inclined pipe 203 to be regenerated.

[0091] The catalyst to be regenerated contacts with the oxygen-containing gas injected through the oxygen-containing gas inlet 401 and the gas distributor 402 and undergoes a complete combustion reaction, releasing heat. After the catalyst is regenerated, part of the regenerated catalyst is supplied to the first reactor through the first regeneration inclined pipe 403, and part of the regenerated catalyst is injected into the reducer through the second regeneration inclined pipe 406, and returned to the second reactor for recycling after reduction. The regenerated flue gas is separated from the entrained catalyst by the cyclone separator 404 and enters the energy recovery system through the regeneration flue gas recovery pipeline 405.

[0092] The crude oil applicable to the catalytic cracking method provided in the present application is selected from one or more mixed crude oils of intermediate base crude oil, intermediate-cycloalkyl crude oil or cycloalkyl-intermediate base crude oil. Any component in the first key component and the second key group of the intermediate base crude oil belongs to the intermediate base attribute; the first key component of the intermediate-cycloalkyl crude oil is the intermediate base attribute and the second key group is the cycloalkyl attribute; the first key component of the cycloalkyl-intermediate base crude oil is the cycloalkyl attribute and the second key group is the intermediate base attribute.

[0093] In one embodiment, the properties of the first raw material low-quality crude oil meet at least one of the following indicators: the characteristic factor K value is not less than 11.5; the relative density is not more than 935 kg / m 3 ; The residual carbon is not more than 10% by weight; The total content of nickel and vanadium is not more than 50 mg / kg.

[0094] In one embodiment, the difficult-to-convert components include the C4 fraction produced by the device and the gaseous hydrocarbons rich in C4 fraction produced by other devices, wherein the content of C4 olefins in the gaseous hydrocarbons rich in C4 fraction is greater than 50% by weight;

[0095] Preferably, the difficult-to-convert component is the C4 fraction produced by the device.

[0096] The C4 component described in the present application refers to low molecular hydrocarbons that exist in gaseous form at room temperature and pressure with C4 fraction as the main component, including alkanes, olefins and alkynes with 4 carbon atoms in the molecule. It includes gaseous hydrocarbon products rich in C4 fraction produced by the device of the present invention, and may also include gaseous hydrocarbons rich in C4 fraction produced by other device processes, among which the C4 fraction produced by the device of the present invention is preferred. The C4 hydrocarbons are preferably C4 fractions rich in olefins, wherein the content of C4 olefins is greater than 50% by weight, preferably greater than 60% by weight, and preferably above 70% by weight.

[0097] In one embodiment, the difficult-to-convert components include light distillate oil produced by the device with a final boiling point of less than 260-300°C and optionally one or more of the following fractions: straight-run naphtha, straight-run kerosene, and straight-run diesel produced by other primary processing devices; topped oil, raffinate oil, hydrocracking light naphtha, pentane oil, coker gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrogenated gasoline, and hydrogenated diesel produced by other secondary processing devices.

[0098] In the present application, the catalytic cracking reaction temperature of the reactor refers to the reactor outlet temperature.

[0099] In one embodiment, the catalytic cracking reaction temperature in the first reactor is 510-650°C, and the weight hourly space velocity is 1-20 hours. -1 The weight ratio of catalyst to oil is (3-50):1, and the catalyst density is 120-290 kg / m 3 , and / or the reaction pressure is 130-450 kPa;

[0100] Preferably, the first raw material enters the first reactor after being preheated and steam atomized, the preheating temperature is 180-350° C., and the water-oil weight ratio is (0.03-0.5):1.

[0101] In one embodiment, the catalyst is supplemented into the first reactor to carry out the cracking reaction, and the supplemented catalyst accounts for 0-30 wt % of the total circulating amount of the catalyst in the first reactor.

[0102] In some embodiments, the supplemental catalyst may account for 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 5 wt%, or 30 wt% of the total catalyst circulation in the first reactor.

[0103] According to the present application, the catalyst is added into the first reactor from one or more supplementary catalyst inlets provided on the side wall of the first reactor, mixed with the reaction product of the feedstock oil and the regenerated catalyst, and the catalytic cracking reaction is continued; wherein, the supplementary catalyst can be one or more selected from the group consisting of a regenerated catalyst, a catalyst to be regenerated, and a semi-regenerated catalyst. The added catalyst can account for 0-30% by weight of the total circulation amount of the catalyst in the first reactor, and the positions of the one or more supplementary catalyst inlets are independently located at a height greater than 0% to 90% of the total height of the first reactor, preferably at a height of 20% to 80% of the total height of the first reactor, and more preferably at a height of 30% to 75%. Supplementing the catalytic cracking catalyst in the fast fluidized bed can adjust the agent-oil ratio within a large range, provide more active centers for the cracking reaction, and at the same time, enhance the flexibility of the reaction temperature regulation, and effectively adjust the gradient of the temperature and catalyst activity in the fast fluidized bed. In addition, supplementing the catalytic cracking catalyst in the fast fluidized bed can maintain the uniformity of the catalyst density of the reactor as much as possible, effectively adjust the catalyst density distribution, ensure that the cracking reaction is fully and effectively carried out, and improve the selectivity of the target product.

[0104] In one embodiment, the second reactor is provided with a main reaction section and one or more difficult-to-convert component feed sections;

[0105] Preferably, the one or more difficult-to-convert component feed sections are each independently arranged in the middle and upstream of the second reactor;

[0106] Preferably, the catalyst density in the difficult-to-convert component feed section is 120-290 kg / m 3 ; and / or

[0107] Preferably, the ratio of the diameter of the difficult-to-convert component feed section to the diameter of the main reaction section is (1.2-1.5):1.

[0108] In one embodiment, one or more of the difficult-to-convert components may be fed into at least one or more identical positions in the feed section of the second reactor, or may be fed into different positions.

[0109] The present invention does not pursue the single-pass conversion rate in the crude oil catalytic cracking process, but adopts the method of recycling the light distillate oil that is difficult to convert, and achieves a higher total conversion rate and a higher selectivity of the target product by setting a specific reaction zone. According to the reaction performance of the difficult-to-convert component, it is introduced into the reactor in the specific feed section of the second reactor. The higher catalyst density and higher catalyst activity in the feed section are conducive to improving the reaction conversion rate and catalytic reaction selectivity of the difficult-to-convert component.

[0110] In one embodiment, the catalytic cracking reaction temperature in the second reactor is 580-750°C, the reaction time is 0.05-5 seconds, the catalyst-oil weight ratio is (1-50):1, and the catalyst density is 20-100 kg / m 3 , and / or the reaction pressure is 130-450 kPa;

[0111] Preferably, the second raw material is introduced into the second reactor after being steam atomized, and the water-oil weight ratio is (0.03-0.5):1.

[0112] In one embodiment, the weight ratio of fresh catalyst to regenerated catalyst in the catalyst reducer is (0.005-0.3):1.

[0113] In one embodiment, the reduction temperature in the catalyst reducer is 550-750° C., and the reduction time is 2-20 minutes; and / or

[0114] The reducing medium is refinery dry gas and / or small molecule alkane, wherein the small molecule alkane is C1-C3 alkane, preferably refinery dry gas.

[0115] In one embodiment, the spent catalyst with coke separated by the oil separation device enters the regenerator after stripping, and contacts with the oxygen-containing gas injected into the regenerator to generate a combustion reaction.

[0116] In the regenerator, the regeneration temperature is 550-750°C, preferably 600-730°C, more preferably 650-720°C;

[0117] The gas superficial velocity is 0.5-3 m / s, preferably 0.8-2.5 m / s, more preferably 1-2 m / s;

[0118] The average residence time of the spent catalyst is 0.6-3 minutes, preferably 0.8-2.5 minutes, more preferably 1-2 minutes.

[0119] In one embodiment, the catalyst comprises 0.01-5wt%, preferably 0.005-2wt% of a metal oxide, based on the dry weight of the catalyst, wherein the metal in the metal oxide is selected from one or more of the following: tin, cobalt, iron, molybdenum, manganese, copper, barium and chromium;

[0120] Preferably, the catalyst comprises:

[0121] 0-70 parts by weight, preferably 5-60 parts by weight, more preferably 10-50 parts by weight of clay,

[0122] 5-99 parts by weight, preferably 10-80 parts by weight, more preferably 20-70 parts by weight of a binder,

[0123] 1-60 parts by weight, preferably 5-45 parts by weight, more preferably 10-40 parts by weight of zeolite, and

[0124] 0.001-5 parts by weight, preferably 0.005-2 parts by weight of a metal oxide,

[0125] The total weight of the catalyst is 100 parts by weight;

[0126] Wherein, the binder is an inorganic oxide binder, preferably silicon dioxide and / or aluminum oxide;

[0127] The zeolite comprises a medium-pore zeolite and an optional large-pore zeolite, wherein the medium-pore zeolite is a ZSM series zeolite and / or a ZRP zeolite, and the large-pore zeolite is one or more selected from rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultrastable Y-type zeolite and high-silicon Y-type zeolite. Preferably, the medium-pore zeolite accounts for 5-100% by weight, preferably 50-90% by weight, and more preferably 20-50% by weight of the total weight of the zeolite;

[0128] The clay is preferably kaolin and / or halloysite.

[0129] In the catalyst used in the present invention, clay is used as a catalyst matrix (ie, a carrier) and an inorganic oxide is used as a binder.

[0130] In the present application, medium-pore zeolite and large-pore zeolite follow the conventional definition in the art, that is, the average pore diameter of medium-pore zeolite is about 0.5-0.6 nm, and the average pore diameter of large-pore zeolite is about 0.7-1.0 nm.

[0131] As an example, the large-pore zeolite can be selected from one or more of rare earth Y (REY) type zeolite, rare earth hydrogen Y (REHY) type zeolite, ultrastable Y type zeolite obtained by different methods and high silicon Y type zeolite. The medium-pore zeolite can be selected from zeolites with MFI structure, such as ZSM series zeolites and / or ZRP zeolites. Optionally, the above-mentioned medium-pore zeolites can also be modified with non-metallic elements such as phosphorus and / or transition metal elements such as iron, cobalt, and nickel. A more detailed description of ZRP zeolite can be found in U.S. Patent No. 5,232,675A. ZSM series zeolites are preferably selected from one or more mixtures of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and other zeolites of similar structure. A more detailed description of ZSM-5 can be found in U.S. Patent No. 3,702,886A.

[0132] The catalyst of the present invention contains variable valence metals, which store and release energy through the gain and loss of electrons or the offset of common electron pairs between the metal and the metal oxide, and provide heat for the catalytic cracking reaction of the difficult-to-convert components, thereby solving the problem of high heat demand for the reaction of the difficult-to-convert components.

[0133] In the method provided by the present invention, the catalyst preparation method adopts the preparation method of conventional catalytic cracking catalyst, which is a preparation method well known to those skilled in the art. The metal can be loaded on the catalyst by impregnation method or slurry method, preferably impregnation method, which are well known to those skilled in the art.

[0134] According to the present application, the separation of the reaction product and the catalyst to be produced is well known to those skilled in the art, for example, it can be carried out using a cyclone separator in a settler, and the method of further separating the reaction oil and gas to obtain dry gas, liquefied gas, light distillate oil in difficult-to-convert components, and cracked heavy oil is also well known to those skilled in the art. The dry gas and liquefied gas can be further separated by conventional separation means in the art to obtain target products such as ethylene and propylene and a C4 fraction.

[0135] The present invention arranges a catalyst reducer in the reaction system, and the catalyst portion regenerated by the regenerator enters the reducer and is mixed with a fresh catalyst. Under the action of a reducing medium (such as refinery dry gas and / or small molecule alkanes), the variable valence metal oxide in the mixed catalyst is reduced and releases energy, and the reduced and regenerated catalyst carries the energy into the second reactor to participate in the reaction, thereby providing heat for the catalytic cracking reaction of the difficult-to-convert components in the second reactor, thereby solving the problem of high heat demand for the reaction of the difficult-to-convert components in the second reactor.

[0136] The present invention also provides a catalytic cracking system, comprising:

[0137] The catalytic cracking reaction unit comprises:

[0138] The first reactor is provided with a pre-lifting medium inlet, a regenerated catalyst inlet, a supplementary catalyst inlet, a feedstock oil inlet and a first oil-agent mixture outlet;

[0139] The second reactor is provided with a pre-lifting section, a feed section, a main reaction section and an outlet section in order from bottom to top, wherein a reduction catalyst inlet and a pre-lifting medium inlet are provided at the bottom of the pre-lifting section, and a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional catalyst outlet are provided in the feed section;

[0140] an oil-agent separation device, the oil-agent separation device being connected to both the first oil-agent mixture outlet of the first reactor and the second oil-agent mixture outlet of the second reactor, so that the first oil-agent mixture from the first reactor and the second oil-agent mixture from the second reactor are separated into reaction oil gas and catalyst to be generated by the oil-agent separation device; and

[0141] A settler, used for settling and collecting the spent catalyst separated by the oil agent separation device, a stripping section is provided below the settler for stripping the spent catalyst, and the stripping section is provided with a spent catalyst outlet and a stripping medium inlet;

[0142] A reaction product separation unit, the reaction product separation unit is connected to the oil agent separation device and is used to separate the reaction oil gas separated by the oil agent separation device;

[0143] A regenerator, wherein the regenerator is provided with an inlet for regenerated catalyst, an inlet for oxygen-containing gas, a gas distributor, a cyclone separator, a regenerated flue gas pipeline and at least one regenerated catalyst outlet; the inlet for regenerated catalyst of the regenerator is fluidly connected to the outlet for regenerated catalyst of the stripping section; one regenerated catalyst outlet is connected to the inlet for regenerated catalyst of the first reactor, for recycling a part of the regenerated catalyst back to the first reactor; and

[0144] A catalyst reducer, wherein the catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a reduced catalyst outlet and a reducing medium inlet; the regenerated catalyst inlet of the catalyst reducer is connected with a regenerated catalyst outlet, so that a part of the regenerated catalyst from the regenerator is reduced in the catalyst reducer; the reduced catalyst outlet of the catalyst reducer is fluidly connected with the reduced catalyst inlet of the second reactor, so that the reduced catalyst is circulated back to the second reactor.

[0145] In one embodiment, the first reactor is provided with one or more supplementary catalyst inlets;

[0146] Preferably, the one or more supplemental catalyst inlets are each independently located at a height greater than 0% to 90% of the total height of the first reactor, preferably at a height of 20% to 80% of the total height of the first reactor, and more preferably at a height of 30% to 75% of the total height of the first reactor.

[0147] The total height of the first reactor is the total height from the feedstock oil inlet to the first oil mixture outlet. Figure 1 Marked as H1.

[0148] In one embodiment, a gas distributor is provided at the bottom of the regenerator, so that the oxygen-containing gas injected through the oxygen-containing gas inlet of the regenerator enters the regenerator through the gas distributor. According to the present application, the gas distributor can adopt a main air distributor well known to those skilled in the art. For example, the main air distributor can be a distribution plate and a distribution pipe. Preferably, the distribution pipe is an annular distribution pipe and a dendrite distribution pipe.

[0149] In one embodiment, the second reactor comprises two feed sections connected in sequence, the first feed section is connected to the pre-lifting section, the second feed section is connected to the main reaction section, and an external catalyst circulation pipeline connecting the two feed sections is arranged between the first feed section and the second feed section;

[0150] Preferably, the distance between the connection port of the external catalyst circulation pipe on the first feed section and the bottom of the first feed section is 0 to 10% of the height of the second feed section; and / or the distance between the catalyst outlet on the second feed section and the bottom of the second feed section is 5% to 20% of the height of the second feed section.

[0151] The catalyst in the second feed section can be selectively returned to the first feed section to improve the catalyst-oil ratio of the first feed section, and can also be selectively removed from the reactor according to the degree of carbonization of the catalyst, which helps to improve the catalyst activity in the reactor.

[0152] The catalytic cracking system of the present application comprises a first reactor and a second reactor, an oil agent separation device, a reaction product separation device, a catalyst regenerator and a reducer, wherein the first reactor and the second reactor are connected to the oil agent separation device, a fluid-connected settler is arranged above the first reactor, and a fluid-connected stripping section is arranged below the first reactor;

[0153] The first reactor is provided with a catalyst inlet, a supplementary catalyst inlet, a feedstock oil inlet and an oil-agent mixture outlet, the stripping section is provided with a catalyst outlet, the settler is provided with a reaction product outlet and an optional oil-agent inlet; the oil-agent separation device is provided with an oil-agent inlet, a catalyst outlet and a reaction product outlet; the second reactor is provided with a pre-lifting section, a first feed section, an optional and second feed section, a main reaction section and an outlet section from bottom to top, the pre-lifting section is provided with a regenerated catalyst inlet and a pre-lifting medium inlet at the bottom, the first feed section is provided with a catalyst inlet, a difficult-to-convert feedstock inlet, a circulating catalyst inlet and an oil-agent mixture outlet, the second feed section is provided with a difficult-to-convert feedstock inlet, a circulating catalyst outlet and an optional catalyst outlet, and an external catalyst circulation pipeline connecting the first feed section and the second feed section is provided between the first feed section and the second feed section;

[0154] The catalyst inlets of the catalyst reducer and the second reactor are fluidly connected to the catalyst outlet of the regenerator, the first reactor and the second reactor are arranged in parallel and connected through an oil agent separation device, the reaction product outlet of the settler is fluidly connected to the oil agent inlet of the oil agent separation device, the oil agent outlet of the first reactor is fluidly connected to the oil agent inlet of the settler or to the oil agent inlet of the oil agent separation device, the reaction product outlet of the oil agent separation device is fluidly connected to the reaction product inlet of the reaction product separation device, and the catalyst outlet of the stripping section is fluidly connected to the catalyst inlet of the regenerator;

[0155] The catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a catalyst outlet and a reducing medium inlet; the catalyst reducer and the second reactor can be arranged in parallel or coaxially.

[0156] According to the present application, the oil agent separation equipment and the reaction product separation equipment are both well known to those skilled in the art. For example, the oil agent separation equipment may include a cyclone separator, a settler and a stripper, etc., and the reaction product separation equipment may be a distillation tower, etc.

[0157] The following examples will further illustrate the present application, but are not intended to limit the present application.

[0158] The raw material oil used in the following examples and comparative examples is imported crude oil, which is an intermediate base crude oil collected from a branch of Sinopec, and its properties are shown in Table 1. The catalyst used in the examples is a DMMC-1 catalyst containing CuO, and the amount of CuO used is 1.0 weight % based on the total weight of the catalyst.

[0159] Example 1

[0160] Using the feedstock oil shown in Table 1 and the DMMC-1 catalyst containing CuO, Figure 1 The experiment was carried out on the pilot plant shown in the figure, wherein the structure of the reactor used is as follows:

[0161] The total height of the first reactor is 7 meters and the inner diameter is 0.3 meters. The height of the second reactor is 5 meters and the inner diameter is 0.2 meters. Two feed sections are set at the lower part. Each feed section is 0.2 meters high and has an inner diameter of 0.3 meters. The first feed section is set with one feed inlet and the second feed section is set with one feed inlet.

[0162] The hot regenerated catalyst of the first regeneration inclined tube 403 enters the lower part of the first reactor and moves upward under the action of the pre-lifting medium. The preheated crude oil and atomized steam are injected into the lower part of the first reactor through the feed pipeline, with a water-oil weight ratio of 0.2:1, and mixed with the existing catalyst in the catalytic cracking reactor to carry out catalytic cracking reaction. The post-reaction logistics enters the subsequent oil agent separation device 204 and the product separation device, wherein a stream of hot regenerated catalyst is added to the first reactor, and its supplement position is located at 50% of the height of the first reactor, wherein the amount of regenerated catalyst added accounts for 10% by weight of the catalyst circulation amount of the reactor;

[0163] The hot regenerated catalyst of the second regeneration inclined tube 406 and the fresh catalyst of the fresh catalyst pipeline 504 enter the catalyst reducer 500, and a reduction reaction occurs under the action of the reducing medium injected through the reducing medium pipeline 501. The reduced high-temperature regenerated catalyst is injected into the pre-lifting section at the bottom of the second reactor through the reducing catalyst inclined tube 503, and moves upward under the action of the pre-lifting medium injected through the second pre-lifting medium pipeline 301. The C4 fraction from the fractionation device and the light distillate oil with a distillation range of less than 300°C enter the bottom of the first feed section through the first feed pipeline 303 of the second reactor, with a water-oil weight ratio of 0.25:1, contact with the existing catalyst in the reactor and move upward, enter the main reaction section 310 and undergo a catalytic cracking reaction, and the reaction oil-agent mixture moves upward. The post-reaction logistics enters the subsequent oil-agent separation equipment and product separation equipment.

[0164] The catalyst with coke obtained from the first reactor and the second reactor and the reaction oil and gas enter the oil agent separation device 204 such as a cyclone separator for gas-solid separation. The reaction oil and gas obtained by separation are led out of the device through the gas collecting chamber 205 and the large oil and gas pipe 206 and enter the subsequent separation system; the catalyst with coke obtained by separation enters the lower part of the settler 200 and enters the regenerator 400 through the inclined pipe 203 to be regenerated.

[0165] The catalyst with coke enters the regenerator and reacts with air to cause a combustion reaction. Part of the regenerated catalyst is returned to the first reactor for reaction circulation, and part of the regenerated catalyst enters the reducer. The regenerated catalyst after reduction is returned to the second reactor for reaction circulation. The regenerated flue gas enters the energy recovery system through the regenerated flue gas recovery pipeline 405.

[0166] The operating conditions and product distribution are listed in Tables 2 and 3. As can be seen from Table 3, the yield of light olefins and light aromatics in this embodiment reaches 47.84% by weight, and accordingly, the total selectivity of light olefins and light aromatics can reach 58.12% by weight.

[0167] Example 2

[0168] Using the feedstock oil shown in Table 1 and the DMMC-1 catalyst containing CuO, Figure 1 The experiment was carried out on the pilot plant shown in the figure, wherein the structure of the reactor used is as follows:

[0169] The total height of the first reactor is 7 meters and the inner diameter is 0.3 meters. The height of the second reactor is 5 meters and the inner diameter is 0.2 meters. Two feed sections are set at the lower part. Each feed section is 0.2 meters high and has an inner diameter of 0.3 meters. The first feed section is provided with one feed inlet and the second feed section is provided with two feed inlets.

[0170] The hot regenerated catalyst in the first regeneration inclined tube 403 enters the lower part of the first reactor and moves upward under the action of the pre-lifting medium. The preheated crude oil and atomized steam are injected into the lower part of the first reactor through the feed pipeline, with a water-oil weight ratio of 0.2:1, and mixed with the existing catalyst in the catalytic cracking reactor to carry out catalytic cracking reaction. The post-reaction logistics enters the subsequent oil separation equipment and product separation equipment, wherein a stream of hot regenerated catalyst is added to the first reactor, and its supplement position is located at 50% of the height of the first reactor, wherein the amount of regenerated catalyst added accounts for 10% by weight of the catalyst circulation amount in the reactor;

[0171] The hot regenerated catalyst of the second regeneration inclined tube 406 and the fresh catalyst of the fresh catalyst pipeline 504 enter the catalyst reducer 500, and a reduction reaction occurs under the action of the reducing medium injected through the reducing medium pipeline 501. The reduced high-temperature regenerated catalyst is injected into the pre-lifting section at the bottom of the second reactor through the reducing catalyst inclined tube 503, and moves upward under the action of the pre-lifting medium injected through the second pre-lifting medium pipeline 301. The C4 fraction enters the bottom of the first feed section through the first feed pipeline 303 of the second reactor, contacts the existing catalyst in the reactor and moves upward. The light distillate oil with a water-to-oil weight ratio of 0.25:1 and a distillation range of less than 300°C enters the bottom of the second feed section through the second feed pipeline 304 of the second reactor, contacts the existing catalyst in the reactor and moves upward, enters the main reaction section 310 and undergoes a catalytic cracking reaction. The reaction oil agent mixture moves upward, and the post-reaction logistics enters the subsequent oil agent separation equipment and product separation equipment.

[0172] The catalyst with coke obtained from the first reactor and the second reactor and the reaction oil and gas enter the oil agent separation device 204 such as a cyclone separator for gas-solid separation. The reaction oil and gas obtained by separation are led out of the device through the gas collecting chamber 205 and the large oil and gas pipe 206 and enter the subsequent separation system; the catalyst with coke obtained by separation enters the lower part of the settler 200 and enters the regenerator 400 through the inclined pipe 203 to be regenerated.

[0173] The catalyst with coke enters the regenerator and reacts with air to cause a combustion reaction. Part of the regenerated catalyst is returned to the first reactor for reaction circulation, and part of the regenerated catalyst enters the reducer. The regenerated catalyst after reduction is returned to the second reactor for reaction circulation. The regenerated flue gas enters the energy recovery system through the regenerated flue gas recovery pipeline 405.

[0174] The operating conditions and product distribution are listed in Table 2 and Table 3. As can be seen from Table 3, the yield of light olefins and light aromatics in this embodiment reaches 49.70% by weight, and accordingly, the total selectivity of light olefins and light aromatics can reach 58.20% by weight.

[0175] Comparative Example 1

[0176] The catalyst used in the comparative example is a commercial catalytic cracking catalyst purchased from the Catalyst Branch of Sinopec Co., Ltd., with a trade name of DMMC-1. The crude oil and DMMC-1 catalyst shown in Table 1 were used to conduct experiments on a medium-sized device. The first reactor was a conventional riser reactor connected in series with a fluidized bed reactor, and the second reactor was a riser reactor. The preheated crude oil enters the riser reaction zone and the fluidized bed reactor in turn to contact with the catalytic cracking catalyst for catalytic cracking reaction. After the reaction, the logistics enters the subsequent oil separation device and product separation equipment. The separated C4 fraction and the light distillate oil with a distillation range of less than 300 enter the second reactor to contact with the catalytic cracking catalyst for catalytic cracking reaction. After the reaction, the logistics enters the oil separation device of the first reactor; the separated catalyst to be regenerated enters the lower part of the regenerator, contacts with the air distributed into the regenerator through the main air distributor to cause a scorching reaction, and the regenerated catalyst returns to the reactor for recycling. The operating conditions and product distribution are listed in Tables 2 and 3.

[0177] It can be seen from the results in Table 3 that the yield of light olefins and light aromatics in this comparative example reaches 35.28% by weight, and the total selectivity of light olefins and light aromatics is 45.40% by weight.

[0178] It can be seen from the results of the above examples and comparative examples that when the catalytic cracking method and system of the present application are used to carry out catalytic cracking reaction of crude oil, the utilization rate of crude oil atoms is high and the yield of light olefins and aromatics is significantly improved.

[0179] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0180] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

[0181] Table 1 Properties of crude oil used

[0182] Crude oil classification Intermediate base crude oil Characteristic factor K value 11.9 <![CDATA[Density (20 °C) / (kg / m 3 )]]> 880.2 Carbon content / weight% 85.91 Hydrogen content / weight% 12.62 Sulfur content / weight% 0.865 Nitrogen content / weight% 0.23 Carbon residue value / weight% 4.09 Metal content / (mg / kg) Fe 3.3 Ni 14 V 12 Na 0.1 Ca 0.3

[0183] Table 2 Reaction conditions of Examples 1, 2 and Comparative Example 1

[0184]

[0185]

[0186] Table 3 Comparison of reaction results of Examples 1, 2 and Comparative Example 1

[0187] Example 1 Example 2 Comparative Example 1 Product distribution, weight % gas 52.05 55.12 40.36 Ethylene 9.06 9.88 3.97 Of which propylene 23.97 24.81 16.51 Of which butene 4.98 5.43 10.59 liquid 38.34 34.98 49.87 Among them, light aromatics 9.83 9.57 7.87 total 100.00 100.00 100.00 Conversion rate, % 82.31 85.39 77.71 Yield of light olefins and light aromatics, % 47.84 49.70 35.28 Selectivity of light olefins and light aromatics, % 58.12 58.20 45.40

Claims

1. A method for direct catalytic cracking of low-quality crude oil, characterized in that: The method comprises: (1) A first feedstock and a regenerated catalyst from a regenerator enter a first reactor for a catalytic cracking reaction, and optionally, the reaction product contacts an introduced supplemental catalyst and continues to react; (2) the second raw material is introduced from the downstream feed section of the second reactor, and is contacted with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction, wherein the catalyst mixture includes a regenerated catalyst and a fresh catalyst; (3) The reaction products of the first reactor and the second reactor and the catalyst to be produced enter the oil separation device for gas-solid separation, and the separated reaction oil and gas are led out of the device for further separation to obtain ethylene, propylene, difficult-to-convert components and other products; (4) the separated catalyst to be regenerated enters the regenerator for oxygen-containing regeneration after stripping, the first part of the regenerated catalyst returns to the first reactor for reaction circulation, the second part of the regenerated catalyst enters the catalyst reducer for reduction reaction and releases energy under the action of the reducing medium, and the regenerated catalyst after reduction enters the second reactor for reaction circulation; Wherein, the first raw material is low-quality crude oil, and the low-quality crude oil is selected from one or more of intermediate base crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate base crude oil; The second raw material is produced by the device itself and / or other difficult-to-convert components, and the difficult-to-convert components are C4 components and / or light distillate oil with a final boiling point of less than 260-300°C.

2. The method according to claim 1, characterized in that The properties of the inferior crude oil meet at least one of the following indicators: the characteristic factor K value is not less than 11.5; the relative density is not more than 935 kg / m 3 ; The residual carbon is not more than 10% by weight; The total content of nickel and vanadium is not more than 50 mg / kg.

3. The method according to claim 1, characterized in that: The difficult-to-convert components include the C4 fraction produced by the device and the gaseous hydrocarbons rich in C4 fraction produced by other devices, wherein the content of C4 olefins in the gaseous hydrocarbons rich in C4 fraction is greater than 50% by weight; Preferably, the difficult-to-convert component is the C4 fraction produced by the device.

4. The method according to claim 1, characterized in that The difficult-to-convert components include light distillate oil produced by the device with a final boiling point of less than 260-300°C and one or more of the following fractions: straight-run naphtha, straight-run kerosene, and straight-run diesel produced by other primary processing devices; topped oil, raffinate oil, hydrocracking light naphtha, pentane oil, coker gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrogenated gasoline, and hydrogenated diesel produced by other secondary processing devices.

5. The method according to claim 1, characterized in that: The catalytic cracking reaction temperature in the first reactor is 510-650°C, and the weight hourly space velocity is 1-20 hours -1 The weight ratio of catalyst to oil is (3-50):1, and the catalyst density is 120-290 kg / m 3 , and / or the reaction pressure is 130-450 kPa; Preferably, the first raw material enters the first reactor after being preheated and steam atomized, the preheating temperature is 180-350° C., and the water-oil weight ratio is (0.03-0.5):

1.

6. The method according to claim 1, characterized in that The supplementary catalyst accounts for 0-30 wt % of the total catalyst circulation in the first reactor.

7. The method according to claim 1, characterized in that The second reactor is provided with a main reaction section and one or more difficult-to-convert component feeding sections; Preferably, the one or more difficult-to-convert component feed sections are each independently arranged in the middle and upstream of the second reactor; Preferably, the catalyst density in the difficult-to-convert component feed section is 120-290 kg / m 3 ; and / or Preferably, the ratio of the diameter of the difficult-to-convert component feed section to the diameter of the main reaction section is (1.2-1.5):

1.

8. The method according to claim 1, characterized in that: The catalytic cracking reaction temperature in the second reactor is 580-750°C, the reaction time is 0.05-5 seconds, the catalyst-oil weight ratio is (1-50):1, and the catalyst density is 20-100 kg / m 3 , and / or the reaction pressure is 130-450 kPa; Preferably, the second raw material is introduced into the second reactor after being steam atomized, and the water-oil weight ratio is (0.03-0.5):

1.

9. The method according to claim 1, characterized in that: The weight ratio of the fresh catalyst to the regenerated catalyst in the catalyst reducer is (0.005-0.3):

1.

10. The method according to claim 1, characterized in that The reduction temperature in the catalyst reducer is 550-750°C. The recovery time is 2-20 minutes; and / or The reducing medium is refinery dry gas and / or small molecule alkane, wherein the small molecule alkane is C1-C3 alkane, preferably refinery dry gas.

11. The method according to claim 1, characterized in that: In the regenerator, the regeneration temperature is 550-750°C, preferably 600-730°C, more preferably 650-720°C; The gas superficial velocity is 0.5-3 m / s, preferably 0.8-2.5 m / s, more preferably 1-2 m / s; The average residence time of the spent catalyst is 0.6-3 minutes, preferably 0.8-2.5 minutes, more preferably 1-2 minutes.

12. The method according to claim 1, characterized in that Based on the dry weight of the catalyst, the catalyst comprises 0.01-5wt%, preferably 0.005-2wt% of a metal oxide, wherein the metal in the metal oxide is selected from one or more of the following: tin, cobalt, iron, molybdenum, manganese, copper, barium and chromium; Preferably, the catalyst comprises: 0-70 parts by weight, preferably 5-60 parts by weight, more preferably 10-50 parts by weight of clay, 5-99 parts by weight, preferably 10-80 parts by weight, more preferably 20-70 parts by weight of a binder, 1-60 parts by weight, preferably 5-45 parts by weight, more preferably 10-40 parts by weight of zeolite, and 0.001-5 parts by weight, preferably 0.005-2 parts by weight of a metal oxide, The total weight of the catalyst is 100 parts by weight; Wherein, the binder is an inorganic oxide binder, preferably silicon dioxide and / or aluminum oxide; The zeolite comprises a medium-pore zeolite and an optional large-pore zeolite, wherein the medium-pore zeolite is a ZSM series zeolite and / or a ZRP zeolite, and the large-pore zeolite is one or more selected from rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultrastable Y-type zeolite and high-silicon Y-type zeolite. Preferably, the medium-pore zeolite accounts for 5-100% by weight, preferably 50-90% by weight, and more preferably 20-50% by weight of the total weight of the zeolite; The clay is preferably kaolin and / or halloysite.

13. A catalytic cracking system comprising: The catalytic cracking reaction unit comprises: The first reactor is provided with a pre-lifting medium inlet, a regenerated catalyst inlet, a supplementary catalyst inlet, a feedstock oil inlet and a first oil-agent mixture outlet; The second reactor is provided with a pre-lifting section, a feed section, a main reaction section and an outlet section in order from bottom to top, wherein a reduction catalyst inlet and a pre-lifting medium inlet are provided at the bottom of the pre-lifting section, and a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional catalyst outlet are provided in the feed section; an oil-agent separation device, the oil-agent separation device being connected to both the first oil-agent mixture outlet of the first reactor and the second oil-agent mixture outlet of the second reactor, so that the first oil-agent mixture from the first reactor and the second oil-agent mixture from the second reactor are separated into reaction oil gas and catalyst to be generated by the oil-agent separation device; and A settler, used for settling and collecting the spent catalyst separated by the oil agent separation device, a stripping section is provided below the settler for stripping the spent catalyst, and the stripping section is provided with a spent catalyst outlet and a stripping medium inlet; A reaction product separation unit, the reaction product separation unit is connected to the oil agent separation device and is used to separate the reaction oil gas separated by the oil agent separation device; A regenerator, wherein the regenerator is provided with an inlet for regenerated catalyst, an inlet for oxygen-containing gas, a gas distributor, a cyclone separator, a regenerated flue gas pipeline and at least one regenerated catalyst outlet; the inlet for regenerated catalyst of the regenerator is fluidly connected to the outlet for regenerated catalyst of the stripping section; one regenerated catalyst outlet is connected to the inlet for regenerated catalyst of the first reactor, for recycling a part of the regenerated catalyst back to the first reactor; and A catalyst reducer, wherein the catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a reduced catalyst outlet and a reducing medium inlet; the regenerated catalyst inlet of the catalyst reducer is connected with a regenerated catalyst outlet, so that a part of the regenerated catalyst from the regenerator is reduced in the catalyst reducer; the reduced catalyst outlet of the catalyst reducer is fluidly connected with the reduced catalyst inlet of the second reactor, so that the reduced catalyst is circulated back to the second reactor.

14. The system according to claim 13, characterized in that The first reactor is provided with one or more supplementary catalyst inlets; Preferably, the one or more supplemental catalyst inlets are each independently located at a height greater than 0% to 90% of the total height of the first reactor, preferably at a height of 20% to 80% of the total height of the first reactor, and more preferably at a height of 30% to 75% of the total height of the first reactor.

15. The system according to claim 13, characterized in that The second reactor comprises two feed sections connected in sequence, the first feed section is connected to the pre-lifting section, the second feed section is connected to the main reaction section, and an external catalyst circulation pipeline connecting the two feed sections is arranged between the first feed section and the second feed section; Preferably, the distance between the connection port of the external catalyst circulation pipe on the first feed section and the bottom of the first feed section is 0 to 10% of the height of the second feed section; and / or the distance between the catalyst outlet on the second feed section and the bottom of the second feed section is 5% to 20% of the height of the second feed section.

Images