CN116925809A

CN116925809A - Method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic pyrolysis of crude oil

Info

Publication number: CN116925809A
Application number: CN202210363980.6A
Authority: CN
Inventors: 李荻; 郭江伟; 石宝珍
Original assignee: Qingdao Jingrun Petrochemical Design & Research Institute Co ltd
Current assignee: Qingdao Jingrun Petrochemical Design & Research Institute Co ltd
Priority date: 2022-04-10
Filing date: 2022-04-10
Publication date: 2023-10-24

Abstract

The invention belongs to the technical field of catalytic conversion of crude oil, and particularly relates to a method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic pyrolysis of crude oil.

Description

Method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic pyrolysis of crude oil

Technical Field

Background

The low-carbon olefin represented by ethylene and propylene is the most basic raw material in the chemical industry, and the existing catalytic conversion technology is by-product low-carbon olefin when producing gasoline and diesel oil, and can not meet the demands of the current market on organic chemical raw materials. Aromatic hydrocarbons are important organic chemical raw materials with the output and the scale being inferior to those of ethylene and propylene, and the derivatives thereof are widely used for producing chemical products and fine chemicals such as chemical fibers, plastics, rubber and the like, and are along with petrochemical industry and textile industryThe demand for aromatic hydrocarbons in the world is increasing with continued development. Natural gas or light petroleum fraction is used as raw material at home and abroad, low-carbon olefin is produced by adopting a steam cracking process in an ethylene combined device, and a large amount of other olefin, aromatic hydrocarbon and other basic raw materials are produced by producing ethylene. Although steam cracking technology has been developed for decades, the technology is perfect, but still has high energy consumption, high production cost and CO ₂ The prior art for producing ethylene and propylene by steam cracking is facing serious examination due to technical limitations such as large discharge amount and difficult regulation of product structure. The catalytic conversion method is utilized to prepare low-carbon olefin, and meanwhile, byproducts of low-carbon olefin such as propylene, butylene and the like and chemical raw materials such as aromatic hydrocarbon and the like are new directions for solving the resource shortage and low-cost production of chemical products, and become important research subjects and hot spot problems at present.

Crude oil is separated into different components under normal pressure or normal pressure, and the different components are treated separately and then are common routes for refineries, and the prior art is a scheme for how to process the fractionated components. In the aspect of preparing low-carbon olefin by catalytic conversion and byproducts of low-carbon olefin such as propylene, butylene and the like, the method mainly comprises the following ideas:

1. the different components are respectively catalyzed in different reactors. For example, CN109575982A provides a method for preparing light olefins and aromatic hydrocarbons by catalytic cracking of crude oil, which comprises desalting and dehydrating crude oil, heating in a heating furnace, and then separating the crude oil into light high boiling components in a distillation tower with a cutting point of 150-300 ℃; the low boiling point component from the top of the tower and the high boiling point component from the bottom of the tower are in contact reaction with the high temperature catalyst in two reactors under the water vapor atmosphere. Virtually all catalytic cracking feedstocks are from atmospheric and vacuum distillation, except for intermediate units that undergo heating furnaces, fractionation, cooling, liquefaction, storage, and the like.

The sauter Arabian company in CN104903427 invented a method for preparing chemicals by catalytic cracking of light and heavy components of crude oil in different downstream reactors respectively.

2. The reactor is internally provided with layered feeding reaction. As in CN1898362 there is provided a process for producing lower olefins and aromatics, wherein the feedstock is contacted with a catalytic cracking catalyst and the reaction is carried out in at least two stages according to the nature of the feedstock, and different liquid reaction products from the fractionating column, except the desired product, are returned to the reactor from different positions for reconversion. CN1215041a provides a method for preparing low-carbon olefins, propylene, aromatic hydrocarbon, etc. by directly converting multiple feed hydrocarbons, wherein multiple groups of feed inlets are arranged on the reactor, so that hydrocarbons with different properties enter the device from different feed inlets, and cracking reaction is performed under the same technological conditions of each part. CN104560154a provides a hydrocarbon catalytic conversion process for the production of higher lower olefins and lighter aromatics, comprising: contacting heavy hydrocarbon raw materials with a cracking catalyst in a reaction zone to carry out catalytic cracking reaction, and then separating to obtain a first carbon deposition catalyst and a first reaction product; injecting light hydrocarbon raw materials from the upstream of the second reactor, injecting medium hydrocarbon raw materials from the middle of the second reactor, and carrying out catalytic cracking reaction; and introducing the reaction mixture generated in the second reactor into a third reactor to continue the reaction, and separating to obtain a second carbon deposition catalyst and a second reaction product. Wherein the cracking catalyst is a cracking catalyst containing modified beta zeolite, and the modified beta zeolite is beta zeolite modified by tourmaline and transition metal M.

3. Outside the raw oil lifting pipe, a reactor is additionally built to make different fractions catalytically converted again, namely, a multi-reactor form is adopted, the reaction zone carries out the conventional raw oil reaction, and one or more fractions such as crude gasoline enter the reactor to be further converted after fractionation to obtain a target product; for example, CN1388216 discloses a catalytic conversion method for preparing propylene, butene and gasoline with low olefin content, which comprises the following steps: (1) Injecting preheated hydrocarbon oil (still liquid) into a riser, contacting and reacting with a catalyst containing pentasil zeolite and Y-type zeolite, and allowing an oil mixture to enter a fluidized bed through the riser; (2) Gasoline is injected into the fluidized bed, contacted and reacted with catalyst from the riser; (3) Separating the oil mixture, and feeding the reacted catalyst into a regenerator for regeneration after steam stripping, wherein the regenerated catalyst returns to the riser for recycling. The method can increase the yield of low-carbon olefin and can also produce high-quality gasoline with low olefin content. CN1258580C discloses a method and system for modifying catalytic gasoline by deep reduction of olefins and octane number, which is to add a catalytic modifying reactor in the reaction-regeneration system of heavy oil catalytic conversion device to make catalytic modifying reaction on catalytic converted gasoline fraction. The upgraded catalytic conversion gasoline fraction may be a whole crude gasoline fraction, a light crude gasoline fraction or a heavy crude gasoline fraction, which are obtained by establishing a secondary condensing system at the top of a fractionating tower.

Crude oil distillation fractionation is a common process and is well known; the catalytic cracking or catalytic cracking raw material mainly comes from a crude oil fractionation device, such as normal pressure heavy oil comes from normal pressure distillation separation, wax oil comes from reduced pressure distillation separation, and naphtha catalytic cracking naphtha comes from normal pressure distillation separation; although catalytic cracker feedstocks are primarily derived from crude oil distillative separations, existing catalytic cracking or cracking techniques have been developed primarily around how to enhance the catalytic cracking effect; there is basically no question concerning how crude oil and catalytic cracking can be directly combined.

The prior art or the patent has the expression that crude oil is separated into heavy components and light components and catalytic cracking is carried out respectively, but the description of how to connect with the catalytic cracking is not suggested, and how to shorten the flow, reduce the investment, reduce the energy consumption and reduce the carbon emission is not related; conventional crude oil distillation separation is a mature and general technology, but the existing crude oil distillation technology cannot realize the intermodal transportation with catalytic cracking, only the separated product can be cooled and liquefied again, and is conveyed to a tank area through a pump to be pressurized by the pump for catalytic cracking; how to realize the crude oil pressurized separation needed by the crude oil distillation and the catalytic cracking intermodal transportation and how to realize the separation proportion and the separation precision adjustment without arranging a side line heat exchange system are the problems which must be solved by the crude oil catalytic cracking.

This expression of the prior art is applicable to all existing catalytic cracking units, all catalytic cracking units, even all secondary processing units such as hydrocracking, are all raw materials from a crude oil fractionation unit, and can be said to be "crude oil fractionation is carried out and enters a certain unit", which is a basic process of oil refining, and technical measures and embodiments are not involved. The patent is a technical link, and a specific technical measure is the core of technical progress.

The existing crude oil fractionation is realized by low pressure and even negative pressure, and is carried out under normal pressure and even reduced pressure (negative pressure), but the catalytic cracking device is pressurized, when the crude oil distillation is directly connected with the catalytic cracking or cracking device, the crude oil separation pressure must be higher than the catalytic cracking reaction pressure, although the crude oil can be separated into different components by the general use of the crude oil written in light of the text to respectively carry out catalytic cracking, the specific technical scheme is not involved, and the existing distillation technology cannot be directly used for crude oil separation and catalytic cracking combined transportation; in addition, the existing crude oil fractionation process realizes crude oil separation by cold reflux through side-line heat extraction and cooling, and a heating furnace and a large amount of heat exchange equipment are required outside a crude oil distillation tower, so that the process is complex, the investment is large, the energy consumption is high, and the carbon emission is high;

the existing flash tower in industry can realize partial component separation without a side line heat exchange part, but the existing flash tower can only separate gas and light naphtha components in a small amount of crude oil due to the reason of no side line heat exchange and the like, and the existing flash tower needs to be realized under normal pressure, so that the component separation precision is low, and the separated components generally enter a distillation tower; especially, the random adjustment of the light and heavy components of crude oil can not be realized, and the crude oil can not be transported together with a catalytic cracking device.

The Exxon Mobil company creatively designs the combination of crude oil fractionation and steam cracking, utilizes the heat of a convection section of a steam cracking furnace to heat crude oil, and separates naphtha components from the crude oil to directly carry out steam cracking, thereby starting the new field of 'crude oil directly preparing olefin or chemicals' worldwide; the scheme becomes a marked milestone technology for directly preparing chemicals from crude oil. The essence of the technology is to combine the design of crude oil fractionation and steam cracking, each part is that the refinery has, and the technology does not relate to new theory or new principle. But the combined design obviously shortens outflow, reduces investment and energy consumption and improves economy. The core progress of the chemical technology is economical.

Disclosure of Invention

The invention aims to: the method is simple in all fields, such as "can be used" and "approximately", and has difficult improvement effect. The technical progress solves the problem of improving the effect. The preparation of ethylene by catalytic pyrolysis is often accompanied with the difficult problem that the heat of the part of the pyrolysis reaction is insufficient and a large amount of heat of the pyrolysis reaction product gas is not well utilized. The invention aims to provide a method for realizing the low-investment low-energy-consumption pressurizing two-component distillation separation of crude oil with high heat utilization rate, simultaneously enabling different components after the crude oil separation to directly perform independent selective catalytic cracking, crude oil separation and catalytic cracking heat intermodal transportation according to the required conditions, simplifying and shortening the flow, and reducing the investment and energy consumption;

specifically: the invention provides a method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic pyrolysis of crude oil, which realizes the distillation separation of two components of crude oil and the preparation of the low-carbon olefin and the aromatic hydrocarbon by direct selective catalytic pyrolysis according to the components in a combined device; the technical scheme adopted is as follows: the crude oil is distilled and separated into two components by utilizing the heat of the catalytic cracking product to carry out catalytic cracking reaction, so that the direct thermal coupling integrated operation of crude oil separation and catalytic cracking is realized; the crude oil is in countercurrent contact and mixing with part of catalytic cracking product gas in the separation tower, so that the gasification of components with low true boiling point of the crude oil is realized, and the crude oil and the catalytic cracking product gas entering the separation tower form two mixed components, namely a light component with low true boiling point and a heavy component with high true boiling point; the light component or light component mixture (actually, the mixture is not only the component in crude oil, but also the material flow entering the separation tower is mixed with the crude oil component) and the heavy component or the weighing component mixture are subjected to catalytic cracking; the process is as follows:

(1) The catalytic cracking reaction product is used as a heat source for crude oil separation, part of catalytic cracking product gas enters a separation tower from the lower part and flows upwards to provide heat required by crude oil distillation or component gasification with low true boiling point, crude oil enters the separation tower above the catalytic cracking product gas, specifically, crude oil liquid enters the separation tower from the upper part of a crude oil inlet or the upper part of the separation tower, the crude oil is dropped by gravity in the separation tower and is mixed with an ascending gas stream, the crude oil is mixed and contacted with the catalytic cracking product gas or the ascending gas, the crude oil is heated by the catalytic cracking product gas or the ascending gas to realize component gasification with low true boiling point, and component liquid with high true boiling point in the crude oil flows downwards and is contacted with the catalytic cracking product gas or the ascending gas; meanwhile, the catalytic cracking product gas or the ascending gas is cooled by cooling, wherein the heavy component or the component with high solid boiling point is liquefied, the liquefied component with high solid boiling point in the catalytic cracking product gas or the ascending gas and the unvaporized liquid component with high solid boiling point in the crude oil are mixed and flow downwards, the heavy component is formed to flow out from the bottom of the separation tower, and the light component or the component with low solid boiling point in the catalytic cracking product gas and the component with low solid boiling point in the crude oil are mixed together to form the light component to flow out of the separation tower upwards, namely flow out from the top of the separation tower;

(2) The high-boiling point liquid phase component flowing out of the bottom of the separation tower, namely heavy component, is pressurized and conveyed to a catalytic cracking reactor by a pump, and enters the fluidized catalytic cracking reactor for catalytic cracking reaction after being atomized by steam; the gas phase low boiling point component separated from the separating tower, namely the light component, is directly or after being reheated and heated, the gas phase is conveyed into a fluidized catalytic cracking reactor for fluidized catalytic cracking, and the heat required by the catalytic cracking reaction is reduced;

in specific implementation, the heating temperature of the light component is not higher than 600 ℃; the heavy component temperature is not higher than 380 ℃, preferably not higher than 350 ℃;

(3) The catalyst from the regenerator enters a catalytic cracking reactor, and flows out of the reactor together with catalytic cracking reaction products after reaction, so that the catalytic cracking reaction of crude oil is realized; the regenerator technicians are well known;

(4) Separating a catalyst from a product after catalytic cracking reaction in the reactor, and returning the catalyst to a regenerator for regeneration after steam stripping for recycling; the reaction product after separating the catalyst flows out of the settler and enters the subsequent product separation part; the settler and stripper technicians are well known;

in specific implementation, the catalytic cracking reaction pressure is 90kpa (gauge pressure) to 200kpa (gauge pressure), and the separation column top pressure is 100kpa (gauge pressure) to 200kpa (gauge pressure).

The method for preparing the low-carbon olefin and the aromatic hydrocarbon by the catalytic pyrolysis of the crude oil, and further, the crude oil enters the separation tower from the upper part of the separation tower;

or, crude oil enters the separation tower in layers at different height positions, crude oil is distributed by entering the separation tower in layers, crude oil is provided for the separation tower in layers, the layered cooling of ascending gas material flows in the separation tower is realized, the effect of reflux after the conventional distillation tower is heated through a side line is achieved, and finally, the temperature control in the separation tower and the separation of two components of crude oil are realized; or, the crude oil enters the separation tower in a layered manner after heat exchange to different temperatures, specifically, or the crude oil entering the separation tower in a layered manner after heating from the heat exchanger enters the separation tower in a layered manner, or the crude oil entering the separation tower in a layered manner is subjected to separate heat exchange, and enters the separation tower in a layered manner at different temperatures after heat exchange, wherein the crude oil with high temperature enters the separation tower in a lower layer.

The method for preparing the light olefins and the aromatic hydrocarbons by the catalytic pyrolysis of the crude oil further comprises the steps of entering a liquid stream above the entering position of the crude oil or at the top of the separation tower, entering the separation tower once or in layers, and further reducing the proportion of heavy components or high-boiling components, namely high-boiling components, in the light components or the low-boiling-point light component mixture which are separated from the top and flow out of the separation tower;

in practice, the liquid stream is a liquid having a true boiling point of 90% or more of the components below 360 ℃, preferably 90% or more of the components are hydrocarbons having a true boiling point below 360 ℃; further, the liquid stream is a gasoline component, diesel oil, or a mixture of gasoline and diesel oil or LCO component, or the liquid stream is derived from gasoline, LCO, or a mixture of gasoline and LCO components of a catalytic cracking reaction product fractionating tower; LCO is light cycle oil;

further, the temperature of the liquid stream is not greater than 250 ℃, preferably not greater than 150 ℃;

the liquid streams enter the separation column in layers at different locations.

In order to improve the crude oil separation precision and reduce the component overlapping, a tray is arranged in the separation tower, and the tray is well known to the skilled person; in practice, trays are preferably positioned below the crude oil inlet, or both below and above the crude oil inlet, or below the liquid stream inlet and below the crude oil inlet. In practice, no more than 6 trays are arranged above each crude oil inlet or/and above each crude oil inlet in order to further reduce pressure drop and energy consumption and improve separation effect. In practice, crude oil and liquid streams are distributed into the separation column via a liquid distributor; liquid distributors are well known to the skilled person.

In the method for preparing the low-carbon olefin and the aromatic hydrocarbon by catalytic pyrolysis of the crude oil, two reactors are further arranged, and the heavy component and the light component are respectively subjected to catalytic pyrolysis reaction in the independent reactors; the light component separated from the separation tower directly enters a gas phase or enters a second reactor for catalytic cracking reaction after being reheated and heated; heavy components separated from the bottom of the separation tower are atomized by steam and then enter the first reactor for catalytic cracking reaction.

In the method for preparing the low-carbon olefin and the aromatic hydrocarbon by catalytic pyrolysis of the crude oil, further, after the catalyst is separated from the reaction product of the catalytic pyrolysis of the first reactor, namely the heavy component catalytic pyrolysis product, directly or after heat exchange, the gas phase continuously enters the second reactor for further catalytic pyrolysis; specifically, after the catalyst is separated from the heavy component catalytic cracking product, the heavy component catalytic cracking product continuously enters a second reactor, namely, a light component reactor for cracking;

further, after the catalyst is separated from the reaction product of the catalytic cracking in the first reactor, namely the heavy component catalytic cracking product, the reaction product is continuously subjected to the cracking reaction downstream of the light component inlet (namely above the inlet) or the light component is subjected to the cracking reaction for 0.2 to 1.5 seconds and then enters the second reactor for further catalytic cracking;

or after the catalyst is separated from the heavy component catalytic cracking product, the heavy component catalytic cracking product continuously enters the second reactor upstream (namely below the inlet) of the light component inlet or before the light component reaction, and further catalytic cracking is carried out, specifically, the heavy component catalytic cracking product is reacted again in the second reactor, and then the light component reaction is carried out.

In the method for preparing the low-carbon olefin and the aromatic hydrocarbon by catalytic pyrolysis of the crude oil, the first reactor and the second reactor are in an ascending mode, the catalyst and the reaction raw materials enter the reactor from the lower part and flow upwards, and flow out of the reactor after the reaction is finished; the heavy component and the light component react in an uplink reactor or an uplink reaction zone, the catalyst and the reaction raw materials enter the reactor or the reaction zone from the lower part, and the reaction raw materials or the products convey the catalyst to flow out of the reactor from the upper part;

alternatively, the first reactor and the second reactor are in a descending form, the catalyst and the reaction raw materials enter the reactor from the upper part, and flow out of the reactor from the bottom; the heavy component and the light component react in a downlink reactor or a downlink reaction zone, the catalyst and the reaction raw materials enter the reactor or the reaction zone from the upper part, and the reaction raw materials or the products convey the catalyst to flow out of the reactor from the lower part or the bottom;

alternatively, the first reactor and the second reactor are in a descending form, and the catalyst and the reactants enter the reactors from the upper part and flow out of the reactors from the lower part; the other reactor is in an upward form, the catalyst and the reaction raw materials enter the reactor from the lower part and flow out of the reactor from the upper part; specifically, one raw material of the heavy component and the light component reacts in an uplink reactor, a catalyst and a reaction raw material enter the reactor from the lower part, a reaction raw material or a product conveying catalyst flows out of the reactor from the upper part, the other raw material reacts in a downlink reactor, the catalyst and the reaction raw material enter the reactor from the upper part, and the reaction raw material or the product conveying catalyst flows out of the reactor from the lower part;

the light component or the second reactor has a catalytic cracking temperature of 580 ℃ to 700 ℃, and the heavy component or the first reactor has a catalytic cracking reaction temperature of 550 ℃ to 670 ℃.

Further, when the first reactor and the second reactor are in the "ascending" form, it is preferable that the first reactor adopts a reaction mode in which the pneumatic transport fluidization form or the pneumatic transport fluidization form is connected in series with a fast fluidized bed or a turbulent fluidized bed in the middle or upper portion of the reactor. In the specific implementation, when the heavy component mixture reacts in the ascending reactor, namely, when the first reactor adopts an ascending reaction form, the first reactor can adopt a 'riser' or pneumatic conveying fluidization form for reaction, or adopts a series connection form of pneumatic conveying and a fast fluidized bed or a turbulent fluidized bed, wherein the fast fluidized bed or the turbulent fluidized bed is arranged in the middle of the reactor; preferably, the fast or turbulent fluidized bed reaction zone catalyst weight hourly space velocity is from 3 (1/h) to 20 (1/h).

The invention is implemented by:

steam is injected into the reactor to reduce the partial pressure of hydrocarbon (the first reactor or the second reactor can be used for reducing the partial pressure of hydrocarbon), and the yield of low-carbon olefin, especially propylene, is increased; specifically, decreasing the partial pressure is beneficial to increasing propylene; the efficiency of injecting steam into the first reactor is high, firstly, the molecular weight of heavy components is large, the effect of injecting steam is obvious, and secondly, the steam injected into the first reactor can continuously enter the second reactor; the injected steam amount is controlled according to the condition that the total steam in the reactor is not more than 60 percent (mass ratio) of the reaction raw materials;

further, non-propylene, ethylene and light aromatic components, such as gasoline components, LCO components, C5 components, C4 components, propane and ethane components, in the reaction products are separated from a subsequent catalytic cracking product separation system, and returned to the reactor for continuous refining and cracking; returning the recycled component to the second reactor or simultaneously partially returning the recycled component to the first reactor for cracking and partially returning the recycled component to the second reactor for cracking; the components with carbon numbers of C5 and below are firstly cracked at the bottom of the reactor when the reactor is recycled;

when C5 and below hydrocarbons are cracked at the bottom of the reactor, the hydrocarbons are in a riser form, or in a fast fluidized bed form or a turbulent fluidized bed form; c4 and the like are common techniques; c5 is a hydrocarbon of 5C atoms and C4 is a hydrocarbon of 4C atoms;

the "riser", pneumatic conveying, fast fluidized bed, turbulent fluidized bed are well known to the skilled person;

in the invention, when recycling is needed, for example, recycling of non-target chemical products in the product of the method or petroleum hydrocarbon of other devices is cracked in the reactor, and light hydrocarbon with the composition of more than 95% and the true boiling point lower than 360 ℃ is catalyzed and cracked in the second reactor preferentially; more than 95% of the stream having a true boiling point above 300 ℃ is preferentially catalytically cracked in the first reactor.

The beneficial effects are that:

in the process of preparing the low-carbon olefin by high-temperature catalytic pyrolysis, because the heat required by the reaction is large, the heat required by the reaction cannot be generally provided by the regeneration of the raw coke, and the heat is often required to be supplemented, and the heat required by the reaction and the excessive heat of the reaction product are balanced, so that the economic benefit is improved; the crude oil has wide components, and the cracking conditions required by naphtha and heavy components are greatly different, so that the crude oil is subjected to selective cracking after light and heavy components are separated, and the cracking efficiency is improved; the invention well solves the problems of crude oil separation and selective catalytic cracking of different components, reduces the investment and energy consumption of crude oil separation, reduces the heat required by catalytic cracking, and has good economic effect.

Drawings

The drawings are merely illustrative of embodiments of the present invention and the implementations are not limited in scope.

FIG. 1 is a schematic process diagram of an embodiment of the present invention;

FIG. 2 is a schematic diagram of a second embodiment of the present invention;

fig. 3 is a schematic diagram of an embodiment.

The numbering in the figures is as follows: 10 first or heavy ends reactor, 20 second or light ends reactor, 30 first settling stripper, 30A second settling stripper, 40 separation column (or flash column);

11 first steam, 21 second steam; 12a first catalyst valve, 22a second catalyst valve; 12A first reactor catalyst inlet, 22A second reactor catalyst inlet; 13 a first catalyst transfer line, 23 a second catalyst transfer line; 16 first reaction feed, 26 second reaction feed; 25 steam; 27 (second reactor) a fast fluidized bed or turbulent fluidized bed reaction zone; 35A first catalyst stripping section, 35A second catalyst stripping section; 38A first spent catalyst transfer pipe, 38A second spent catalyst transfer pipe;

f0 crude oil, F1 (separation overhead) liquid stream; f01 catalytic cracking product gas (catalytic cracking product entering a separation tower), F02 separating tower bottom stream or heavy component mixture, F03 separating tower top stream or light component mixture, F06 heavy component catalytic cracking product or effluent first sedimentation stripper reaction product, F06B separating heavy component catalytic cracking product (sent out of a reaction system or continuous reaction), F07 second reactor cracking reaction product or light component cracking reaction product; an FC catalyst; FRC traffic signal.

Detailed Description

The following specific examples are given to illustrate the technical aspects of the present invention, but the scope of the present invention is not limited thereto.

The specific implementation process is as follows:

embodiment one:

the method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic cracking of crude oil as shown in fig. 1 is characterized in that two catalytic cracking reaction systems or reactors of a first reactor 10 and a second reactor 20 are arranged, crude oil F0 after desalination and dehydration treatment is subjected to pressure by a pump at a temperature of 110-160 ℃, and a reflux stream of a separation tower enters a separation tower 40; a part of the reaction product of the heavy component F02, i.e., the heavy component catalytic cracking product F06, from the bottom of the separation column enters the separation column 40 as catalytic cracking product gas F01; crude oil F0 enters the separation column 40 above the catalytic cracking product gas F01; liquid stream F1 having a temperature below 250 ℃ enters the separation column 40 from the top of the separation column; crude oil F0 and catalytic cracking product gas F01 entering a separation tower 40 are separated into light component F03 and heavy component F02 through mixing and mass transfer;

a first reactor 10 for cracking heavy component F02 and a second reactor 20 for cracking light component F03 are arranged beside the separation tower 40, and the first reactor 10 and the second reactor 20 are in a descending form; the light component F03 separated from the top of the separation tower is atomized by steam 25 and then directly enters a light component reactor, namely a second reactor 20, as a second reaction raw material 26 in a gas phase, and a light component cracking reaction product F07 is separated from a catalyst and then flows out of the second reactor 20; atomizing heavy component F02 flowing out from the bottom of the separation tower by steam, and then entering a heavy component reactor, namely a first reactor 10 for catalytic pyrolysis; the first steam 11 is respectively introduced into the first reactor 10, the second steam 21 is introduced into the second reactor 20, and fluidization in the reactors is realized;

after the catalyst is separated from the heavy component catalytic cracking product F06, a part of the heavy component catalytic cracking product F06B flows out of the first reactor 10 as a separated heavy component catalytic cracking product F06B and is sent out of the reaction system, and a part of the heavy component catalytic cracking product F06B enters the separation tower 40 as a catalytic cracking product gas F01 to provide a heat source for crude oil separation; in practice, the catalytic cracking product gas F01 can also come from a light component cracking reaction product F07; the crude oil F0 temperature is 100 ℃ to 250 ℃, the reaction pressure of the first reactor 10 is 120kpa to 200kpa, the reaction pressure of the second reactor 20 is 90kpa to 160kpa, and the pressure of the separation column top is 120kpa to 180 kpa.

Embodiment two:

a method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic cracking of crude oil as shown in figure 2,

after the catalyst is separated from the heavy component catalytic cracking product F06 in the first reactor 10, a part of the heavy component catalytic cracking product F06 enters the separation tower 40 as catalytic cracking product gas F01, and a part of the heavy component catalytic cracking product F06B continuously enters the second reactor 20 for continuous reaction and further catalytic cracking;

the reaction pressure of the first reactor 10 is 130 kpa to 180kpa, the top pressure of the separation column 40 is lower than the reaction pressure of the first reactor 10 by 5kpa to 15kpa, and the reaction pressure of the second reactor 20 is lower than the reaction pressure of the first reactor 10 by 30kpa to 45kpa;

other embodiments are the same as in the first embodiment.

Examples:

the method for preparing light olefins and aromatic hydrocarbons by catalytic cracking of crude oil as shown in fig. 3, the first reactor 10 and the second reactor 20 are both in an upstream form;

the first reactor 10 adopts a riser reaction mode, the second reactor 20 adopts a rapid fluidized bed or turbulent fluidized bed reaction zone 27 and a riser series mode, and the rapid fluidized bed or turbulent fluidized bed reaction zone 27 is arranged below;

the first reactor catalyst inlet 12A arranged at the bottom of the first reactor 10 is communicated with a first spent catalyst conveying pipe 38 of the first catalyst stripping section 35 through a first catalyst conveying pipeline 13, the outlet of the first reactor 10 is communicated with a gas-solid separator in the first sedimentation stripper 30, and the first reactor catalyst inlet 12A is provided with a first catalyst valve 12;

a second reactor catalyst inlet 22A arranged below the fast fluidized bed or turbulent fluidized bed reaction zone 27 of the second reactor 20 is communicated with a second spent catalyst conveying pipe 38A of a second catalyst stripping section 35A through a second catalyst conveying pipeline 23, an outlet of the second reactor 20 is communicated with a gas-solid separator in a second sedimentation stripper 30A, and a second catalyst valve 22 is arranged on the second reactor catalyst inlet 22A;

the heavy component F02 flowing out from the bottom of the separation tower is atomized by steam and then enters the first reactor 10 as a first reaction raw material 16 for catalytic cracking;

the other part is the same as the first embodiment;

the reaction system shown in figure 3 is adopted to prepare low-carbon olefin by catalytic conversion of crude oil;

crude oil F0 properties: density 0.85, hydrogen content 13.0, K value 12.5, ni content less than 3.0ppm, V content 0.3ppm;

crude oil separation conditions: crude oil F0 temperature 125 ℃; liquid stream F1 is 40 ℃ gasoline component from the catalytic cracking product fractionation column, liquid stream F1 flow is 5% of crude oil F0; the separation column 40 has 3 trays below and above the crude inlet, respectively; the pressure of the separation column 40 is 155kpa (gauge pressure), the temperature of the top of the column is 270 ℃, and the temperature of the bottom of the column is 350 ℃;

reaction conditions:

the first reactor 10 adopts a riser reaction mode, the operating pressure of the first sedimentation stripper 30 is 165kpa, the pressure of the separation tower 40 is 155kpa (gauge pressure), the reaction temperature of the first reactor 10 is 620 ℃, the reaction time is 1.8 seconds, and the steam proportion of the first reactor 10 is 35% of the amount of the heavy component F02; the second settling stripper 30A operates at a pressure of 115kpa (gauge pressure), the primary reaction zone of the second reactor 20, i.e., the fast fluidized bed or turbulent fluidized bed reaction zone 27, takes the form of a fast fluidized bed with a gas flow rate of 1.5m/s, a reaction time of 2.0 seconds, a reaction temperature of 650 ℃, and a steam ratio of 40%;

regenerator (not shown): the regeneration temperature is controlled at 720 ℃. Table 1 is example single pass conversion gas product distribution (predictions).

Table 1 example single pass conversion gas product distribution

Component (A)	Unit (weight)
		Dry gas	20
Methane	3.0
		Ethylene	13.6
Liquefied gas	43
		Propylene	21.6

Claims

1. A method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic pyrolysis of crude oil is characterized in that the heat of a catalytic pyrolysis product is utilized to make the crude oil distilled and separated into two components for catalytic pyrolysis reaction, so that direct thermal coupling integrated operation of crude oil separation and catalytic pyrolysis is realized; the crude oil is in countercurrent contact and mixing with part of catalytic cracking product gas in the separation tower, so that the gasification of components with low true boiling point of the crude oil is realized, and the crude oil and the catalytic cracking product gas entering the separation tower form two mixed components, namely a light component with low true boiling point and a heavy component with high true boiling point; catalytically cracking the light component and the heavy component; the process is as follows:

(1) Part of the catalytic cracking product gas (F01) enters a separation tower (40) and flows upwards to provide heat required by distillation of crude oil or gasification of components with low true boiling point, crude oil (F0) enters the separation tower (40) above the catalytic cracking product gas (F01), the crude oil (F0) is in mixed contact with the catalytic cracking product gas (F01) or the ascending gas, the crude oil (F0) is heated by the catalytic cracking product gas (F01) or the ascending gas to realize gasification of components with low true boiling point, and component liquid with high true boiling point in the crude oil flows downwards to be in contact with the catalytic cracking product gas (F01) or the ascending gas; simultaneously, the catalytic cracking product gas (F01) or the ascending gas is cooled, wherein the heavy component or the component with high solid boiling point is liquefied, the liquefied component in the catalytic cracking product gas (F01) or the ascending gas and the component with high solid boiling point in the crude oil are mixed and flow downwards, and form heavy component (F02) which flows out from the bottom of the separation tower, and the light component or the component with low solid boiling point in the catalytic cracking product gas (F01) and the component with low solid boiling point in the crude oil are mixed together with steam to form light component (F03) which flows upwards out of the separation tower (40);

(2) The high-boiling point liquid phase component (F02) flowing out of the bottom of the separation tower is conveyed to a catalytic cracking reactor to be atomized by steam and then enters the catalytic cracking reactor to carry out catalytic cracking reaction; the gas phase low boiling point component, namely the light component (F03), directly or after reheating, enters a catalytic cracking reactor to carry out fluidization catalytic cracking;

(3) The catalyst (FC) from the regenerator enters a catalytic cracking reactor, and flows out of the reactor together with a reaction product after the reaction to realize the catalytic cracking reaction of crude oil;

(4) Separating a catalyst (FC) from the product after the reaction in the reactor, and returning the catalyst (FC) to a regenerator for regeneration after steam stripping for recycling; the reaction product after separation of the catalyst (FC) is discharged from the settler.

2. The method for preparing light olefins and aromatic hydrocarbons by catalytic cracking of crude oil according to claim 1, wherein the method comprises the following steps: the crude oil (F0) enters a separation tower (40) from the upper part of the separation tower;

alternatively, the crude oil (F0) enters the separation tower (40) in layers at different positions, and the temperature control in the separation tower (40) is realized through the layered distribution of the crude oil (F0); alternatively, crude oil (F0) is subjected to heat exchange to different temperatures and then enters the separation tower (40) in a layered manner.

3. The method for preparing light olefins and aromatic hydrocarbons by catalytic cracking of crude oil according to claim 1, wherein the method comprises the following steps: a liquid stream (F1) is introduced above the crude oil (F0) or at the top of the separation column (40), said liquid stream (F1) entering the separation column (40) either once or in layers, further reducing the high boiling components in the light components (F03) exiting the separation column (40) from the top.

4. The method for preparing light olefins and aromatic hydrocarbons by catalytic cracking of crude oil according to claim 1, wherein the method comprises the following steps: two reactors are arranged, and light components (F03) separated from the separation tower (40) directly enter a gas phase or enter a second reactor (20) for catalytic pyrolysis after reheating and heating; heavy component (F02) separated from the bottom of the separation tower is atomized by steam and then enters the first reactor (10) for catalytic cracking reaction.

5. The method for preparing light olefins and aromatic hydrocarbon by catalytic cracking of crude oil according to claim 4, wherein the method comprises the following steps: after the catalyst is separated from the reaction product of the catalytic pyrolysis of the first reactor, namely the heavy component catalytic pyrolysis product (F06), directly or after heat exchange, the gas phase continuously enters the second reactor (20) for further catalytic pyrolysis.

6. The method for preparing light olefins and aromatic hydrocarbon by catalytic cracking of crude oil according to claim 5, wherein the method comprises the following steps: after the catalyst is separated from the heavy component catalytic cracking product (F06), the heavy component catalytic cracking product continuously enters a second reactor (20) downstream of a light component inlet or after the light component (F03) reacts, and is subjected to further catalytic cracking;

or after the catalyst is separated from the heavy component catalytic cracking product (F06), the heavy component catalytic cracking product is continuously fed into the second reactor (20) upstream of a light component inlet or before the light component (F03) reacts, and further catalytic cracking is performed.

7. The method for preparing light olefins and aromatic hydrocarbon by catalytic cracking of crude oil according to claim 4, wherein the method comprises the following steps: the first reactor (10) and the second reactor (20) are in an 'upward' form, the catalyst and the reaction raw materials enter the reactors from the lower part and flow upwards, and the reaction raw materials flow out of the reactors after the reaction is completed;

alternatively, the first reactor (10) and the second reactor (20) are in a descending form, the catalyst and the reaction raw materials enter the reactors from the upper part, and flow out of the reactors from the bottom.

8. The method for preparing light olefins and aromatic hydrocarbon by catalytic cracking of crude oil according to claim 4, wherein the method comprises the following steps: the first reactor (10) and the second reactor (20), wherein one reactor is in a descending form, the catalyst and the reactants enter the reactor from the upper part and flow out of the reactor from the lower part; the other reactor is in an upward form, the catalyst and the reaction raw materials enter the reactor from the lower part and flow out of the reactor from the upper part.

9. The method for preparing light olefins and aromatic hydrocarbons by catalytic cracking of crude oil according to claim 7 or 8, wherein: when the first reactor (10) is in an 'upward' form, the first reactor (10) is in a pneumatic conveying fluidization form or a reaction mode of connecting a pneumatic conveying fluidization form and a fast fluidized bed or a turbulent fluidized bed in series, wherein the fast fluidized bed or the turbulent fluidized bed is arranged in the middle part or the upper part of the reactor.

10. A method for preparing light olefins and aromatic hydrocarbons by catalytic cracking of crude oil according to claims 1 and 3, wherein: in the separation tower (40), trays are arranged below the crude oil inlet, or are arranged below the crude oil inlet and above the crude oil inlet at the same time, or are arranged below the liquid stream inlet and below the crude oil inlet.