CN115322807B

CN115322807B - Method and device for preparing low-carbon olefin by catalytic conversion of crude oil

Info

Publication number: CN115322807B
Application number: CN202110508019.7A
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: 2021-05-11
Filing date: 2021-05-11
Publication date: 2023-10-27
Anticipated expiration: 2041-05-11
Also published as: CN115322807A

Abstract

The invention relates to a method for preparing low-carbon olefin by catalytic conversion of crude oil, belonging to the technical field of catalytic conversion of crude oil. The crude oil is heated by a heating furnace or a heat exchanger and then reacts in a riser reactor, and the reaction product enters a downlink reactor to carry out catalytic cracking reaction, so that the low-carbon olefin is prepared by catalytic cracking of the crude oil. The invention also provides a device for realizing the method.

Description

Method and device for preparing low-carbon olefin by catalytic conversion of crude oil

Technical Field

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

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 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 along with the continuous development of petrochemical industry and textile industry, the world demand for aromatic hydrocarbons is also continuously increasing. 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.

In the aspect of preparing low-carbon olefin by catalytic conversion and preparing low-carbon olefin such as propylene, butylene and the like as byproducts, the method mainly comprises the following steps:

1. the reaction raw materials are divided into light and heavy fractions through a distillation tower, and catalytic reactions are carried out in different reactors respectively. For example, CN109575982A provides a method for preparing low-carbon olefin and aromatic hydrocarbon by catalytic cracking of crude oil, the crude oil is desalted and dehydrated, then is heated in a heating furnace, and then is fed into a distillation tower to separate the crude oil into light and heavy components, and the cutting point is between 150 and 300 ℃; the light component from the top of the tower and the heavy component from the bottom of the tower are in contact reaction with the high-temperature catalyst in two reactors under the water vapor atmosphere.

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 riser reactor to carry out catalytic cracking reaction, and then separating to obtain a riser carbon deposition catalyst and a riser 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 phosphorus 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 lifting pipe reactor is used for carrying out 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.

4. The light raw material produces low-carbon olefin. CN104557378A discloses a method for producing propylene by catalytic pyrolysis of naphtha. The method comprises the following steps: (1) Under the pretreatment condition, naphtha is contacted with a pretreatment agent to obtain treated oil with reduced basic nitrogen content; (2) And (3) under the condition of naphtha catalytic cracking reaction, the treated oil and water obtained in the step (1) are contacted with a catalyst to obtain a catalytic cracking product.

5. To increase the yield of light olefins, the addition of "co-catalyst" suitable for cracking small molecule hydrocarbons, typically 5-8% of the heavy oil reaction catalyst, can be used, with an increase of 1-1.5% of propylene.

The reaction temperature for preparing the low-carbon olefin from the crude oil is higher and is generally higher than 650 ℃; the crude oil component is wider, and the reaction process is a process of gradually cracking and gradually reducing the molecular weight; the small molecules are difficult to activate, the higher the required reaction temperature is, the higher the temperature is, the natural reheating and cracking reaction is carried out, and the selectivity of the target product is affected; how to distribute the reaction temperature and the molecular characteristics of crude oil, balance the catalytic cracking reaction and the thermal cracking reaction, and realize the limit control of the reaction; the desirable reaction process is that the specific gravity of the catalytic reaction is increased as much as possible in the macromolecule cracking stage of heavy oil and the like, the thermal cracking is limited, the temperature is gradually increased in the lower molecule cracking stage, and the thermal cracking reaction proportion is increased; however, the heat in the reaction process of the prior art is provided in the inlet area of the reactor, the reaction is gradually cooled, especially for the reaction for preparing low-carbon olefin, the reaction temperature in the initial stage, namely the heavy oil cracking stage at the lower part of the reactor, is higher due to the high reaction temperature, and the heavy components directly perform the thermal cracking reaction, so that the effect of the catalytic cracking reaction is reduced.

Disclosure of Invention

The invention aims to provide a method for preparing low-carbon olefin by catalytic conversion of crude oil, which is characterized in that the crude oil is heated by a heating furnace or a heat exchanger and then reacts in a riser reactor, and reaction products enter a downlink reactor to perform catalytic cracking reaction, so that the high-yield preparation of the low-carbon olefin is realized. And a device for realizing the method is also provided.

The technical scheme of the invention is as follows:

the method for preparing low-carbon olefin by catalytic conversion of crude oil comprises preheating/heating desalted and dehydrated crude oil in a heating furnace or a heat exchanger, and performing catalytic cracking on the device for preparing low-carbon olefin by catalytic conversion; the device for preparing the low-carbon olefin through catalytic conversion is provided with a reaction system and a catalyst regeneration system; the reaction system is provided with at least one riser reactor and one downlink reactor; the catalyst regeneration system is provided with a regenerator, and the specific process is as follows:

(1) The desalted and dehydrated crude oil is directly or preheated and then is subjected to catalytic cracking reaction in a riser reactor, and a regenerated catalyst from a regenerator enters the riser reactor from a regenerator inlet of the riser reactor at the bottom to provide catalyst environment and heat; the product generated by the reaction is subjected to gas-solid separation in a settler through a cyclone separator, the separated catalyst is settled to a stripping section below for steam stripping, the stripped catalyst is returned to a regenerator for regeneration, and the regenerated catalyst enters a riser reactor for recycling; the reaction product of the riser reactor after the catalyst is separated is sent into a downlink reactor for continuous reaction;

when the method is implemented, steam is added before crude oil is preheated, and the crude oil is atomized by the steam before entering a riser reactor;

further, the riser reactor is supplemented with steam accounting for 10 to 50 percent of the mass ratio of the reaction raw materials in the riser reactor:

furthermore, the crude oil can exchange heat with the reaction product of the down reactor or the reaction product of the riser reactor, so as to preheat the crude oil;

(2) The reaction product of the riser reactor after separating the catalyst enters a downlink reactor for catalytic cracking reaction, the regenerated catalyst from the regenerator enters the downlink reactor from the top, the reaction product of the downlink reactor flows out of the downlink reactor downwards, the reaction product of the downlink reactor flows out of a settler of a downlink reaction system after being separated from the catalyst, the separated catalyst is stripped in a stripping section of the downlink reaction system, and the stripped catalyst enters the regenerator for regeneration from a to-be-regenerated catalyst conveying pipe and enters the downlink reactor for recycling after regeneration. In the specific implementation, steam can be added into the reaction product of the riser reactor or the downlink reactor, and the steam addition amount accounts for 0-50% of the raw oil amount.

In the method for preparing the low-carbon olefin by catalytic conversion of the crude oil, preferably, C4 and/or light hydrocarbon components react in a downlink reactor; or the C4 and/or light hydrocarbon component and the reaction product of the riser reactor react in a common downlink reactor respectively, or the C4 and/or light hydrocarbon component is mixed with the reaction product of the riser reactor and then enters the downlink reactor for reaction, or the C4 and/or light hydrocarbon component reacts in an independent downlink reactor; the regenerated catalyst is provided from separate regeneration risers or from a common regeneration riser as the different component feeds react in different downgoing reactors. More preferably, the light hydrocarbon components having an external boiling point below 360 ℃ are reacted in a downstream reactor; the light hydrocarbon component and the reaction product of the riser reactor react in a common downlink reactor, or the light hydrocarbon component is firstly mixed with the reaction product of the riser reactor and then reacts in the same downlink reactor, or the light hydrocarbon component reacts in an independent downlink reactor, and when different component raw materials react in different downlink reactors, the regenerated catalyst is provided from respective regenerated risers or from common regenerated risers. Or more preferably, the components with boiling points lower than 360 ℃ in the reaction product of the downlink reactor are hydrogenated and then reacted in the downlink reactor, and when the method is implemented, the components with boiling points lower than 280 ℃ in the reaction product of the downlink reactor are preferably reacted in the downlink reactor. In specific implementation, the light hydrocarbon component is petroleum hydrocarbon with a boiling point lower than 360 ℃, including but not limited to external light hydrocarbon, light hydrocarbon separated from a riser reactor reaction product or a downgoing reactor reaction product, and the light hydrocarbon includes but not limited to a C4 component, a naphtha component, a component after heavy gasoline hydrogenation and a component after diesel hydrogenation.

When the method is implemented, the components with boiling points higher than 200 ℃ in the reaction products of the downlink reactor are recycled in the riser reactor, or the components are recycled in the riser reactor after hydrogenation; preferably components having boiling points above 350 ℃ are recycled in the riser reactor.

In the above method for producing light olefins by catalytic conversion of crude oil, heavy oil or heavy cycle oil or fuel oil is preferably supplemented at a single or multiple positions of the stripping section of the downgoing reaction system before the outlet of the riser reactor, before the outlet of the downgoing reactor. Because the reaction heat required for preparing the low-carbon olefin is more, when the heat provided by the raw coke regeneration of the crude oil reaction can not meet the reaction requirement, heavy oil is supplemented at the single or multiple positions so as to increase the raw coke amount and improve the heat supply capability of catalyst regeneration.

In the method, preferably, the fuel is supplemented in the regenerator, and when the regeneration of the raw coke for preparing the low-carbon olefin by the crude oil is insufficient to provide the heat required by the reaction, the heat is supplemented to the reaction system by supplementing the fuel in the regenerator.

In the method for preparing the low-carbon olefin by catalytic conversion of the crude oil, preferably, the reaction pressure gauge pressure of the riser reactor is 0.10-0.20 Mpa, the reaction outlet temperature is 550-670 ℃, and the reaction time is 1.0-3.0 seconds; the reaction temperature of the downlink reactor is 620-720 ℃, and the reaction time is 0.1-1.5 seconds.

According to the method for preparing the low-carbon olefin by catalytic conversion of the crude oil, further, the crude oil is subjected to hydrotreatment to remove heavy metal, sulfur and basic nitrogen elements, and after the hydrogen content improvement property is improved, the crude oil enters a device for preparing the low-carbon olefin by catalytic conversion to prepare the low-carbon olefin by catalytic conversion. The crude oil hydrotreating engineering company technicians are well known and the product separation column liquid product hydrogenation can be performed by the engineering company technicians.

The invention also provides a device for preparing low-carbon olefin by catalytic conversion of crude oil, wherein a reaction system and a catalyst regeneration system are arranged at the downstream of a heating furnace or a heat exchanger;

the reaction system is provided with a riser reactor, a settler, a stripping section and a downstream reactor, a downstream reaction system settler and a downstream reaction system stripping section; the catalyst regeneration system is provided with a regenerator;

the riser reactor comprises a riser reactor reaction zone; the riser reactor regenerant inlet at the lower part of the riser reactor reaction zone is communicated with the first regenerant outlet of the regenerator through a first regeneration vertical pipe; a crude oil inlet is arranged at the lower part of the riser reactor, and the crude oil inlet is communicated with the heating furnace or the heat exchanger; a downlink reaction raw material inlet is arranged at the top of the downlink reactor and is communicated with a reaction product outlet of a riser reactor arranged at the top of the settler;

the upper part of the descending reactor is provided with a regenerated catalyst inlet which is communicated with the regenerator through a second regenerated vertical pipe; the outlet of the lower part of the descending reactor is connected with a gas-solid separator in a settler of the descending reaction system, and when the descending reactor is implemented, the outlet of the descending reactor is connected with a cyclone gas-solid separator to serve as a primary gas-solid separator, and the cyclone gas-solid separator is well known to technicians; the stripping section of the descending reaction system is arranged below the settler of the descending reaction system.

Preferably, the device for preparing the low-carbon olefin by catalytic conversion of crude oil further comprises a plurality of downlink reactors which are arranged in parallel with the downlink reactor (R20), wherein the raw material inlets at the top of each downlink reactor are respectively communicated with different raw material pipelines so as to realize the reaction of different raw materials in different downlink reactors.

In the device for preparing the low-carbon olefin by catalytic conversion of crude oil, preferably, a regenerated catalyst distributor is arranged at the top of the downstream reactor, the regenerated catalyst inlet is arranged at the top of the regenerated catalyst distributor, and the regenerated catalyst firstly enters the regenerated catalyst distributor and then enters the downstream reactor.

The method adopts the scheme of different conditions for processing the components of the crude oil, optimizes the reaction conditions, exerts the characteristics of catalytic reaction and thermal reaction, and forms a combined scheme, thereby increasing the reaction and product selectivity and improving the efficiency.

Drawings

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

The numbering in the figures is as follows:

r10 riser reactor; the R11 riser catalyst lift gas; an R11A riser catalyst lift gas inlet, an R12 riser reactor reactant feed stream, an R12A crude oil inlet; r14 riser reactor reaction product, R14A riser reactor regenerant inlet, R15 steam, R16 light hydrocarbon component (external component or recycled component in the product), R17 riser reactor reaction zone; r19 heavy petroleum hydrocarbons or heavy cycle oil; r20 downgoing reactor, R21 steam a, R24 downgoing reactor reaction product;

s10 (riser reaction system) stripping section, S11 stripping component; s12, a standby vertical pipe and a VD1 standby agent slide valve; s19 heavy petroleum hydrocarbon or heavy cycle oil a; s20, a stripping section of a downlink reaction system, S22, a spent catalyst conveying pipe; s29 heavy petroleum hydrocarbons or heavy cycle oil B;

d1 regenerated catalyst distributor; d10 (riser reaction system) settler, D11 settling cyclone, D12A riser reactor reaction product outlet, D20 downgoing reaction system settler; a0 heating furnace or heat exchanger;

a G10 regenerator, a G11 catalyst regeneration gas, a G11A regeneration gas inlet, a G12 dense phase fluidized bed regeneration zone, a G12A spent agent inlet, a G13 fuel oil A, a G14 first regeneration vertical pipe (riser regenerated catalyst conveying pipe), a VG1 regeneration slide valve, a G14A first regeneration agent outlet, a G15 regenerator dilute phase zone, a G16 regenerator cyclone separator, a G17 burnt flue gas and a G17A flue gas outlet; g18 fuel, G19 regenerator char region; g24 second regeneration riser (downgoing reactor regenerated catalyst transfer line). F0 crude, TI temperature indication, TC temperature control signal.

Description of the embodiments

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:

pressurizing desalted and dehydrated crude oil F0 to 0.8-1.6 MPa by a pump, heating to 220-370 ℃ in a crude oil heating furnace or a heat exchanger A0, and introducing the heated crude oil into a device for preparing low-carbon olefin by catalytic cracking for fluidization catalysis, or introducing the hydrotreated crude oil into a device for preparing low-carbon olefin by catalytic cracking for fluidization catalysis;

crude oil firstly enters a riser reactor R10 to carry out heavy component macromolecule catalytic cracking reaction, the reaction temperature is about 550-670 ℃, the reaction time is 1.0-3.0 seconds, then the reaction product gas and the catalyst are carried out gas-solid separation in a settler together, and the riser reactor reaction product after the catalyst is separated out flows out of the settler D10;

the reaction product R14 of the riser reactor enters the downlink reactor R20 again for continuous reaction; the reaction temperature is 620-720 ℃, and the reaction time is 0.1-1.5 seconds; and (3) carrying out gas-solid separation on the reacted product in the descending reaction system settler D20, and enabling the catalyst-separated descending reactor reaction product R24 to flow out of the descending reaction system settler D20.

Embodiment one:

the method for preparing low-carbon olefin by catalytic conversion of crude oil of the embodiment adopts the device shown in fig. 1, and a reaction system and a catalyst regeneration system are arranged at the downstream of a crude oil heating furnace or a heat exchanger A0; the reaction system comprises a riser reaction system and a downlink reaction system; the riser reaction system comprises a riser reactor R10, a settler D10 and a stripping section S10; the downstream reaction system comprises a downstream reactor R20, a downstream reaction system settler D20 and a downstream reaction system stripping section S20; the catalyst regeneration system is provided with a regenerator G10; the crude oil F0 is adopted as a raw material, the desalted and dehydrated crude oil F0 is pressurized and preheated in a crude oil heating furnace or a heat exchanger A0, a riser reactor R10 is first used after steam atomization, a reaction product is separated out of a catalyst, the obtained riser reactor reaction product R14 is then fed into a downlink reactor R20 for reaction, and regenerated catalyst is respectively fed into the riser reactor R10 and the downlink reactor R20 from a first regeneration vertical pipe G14 and a second regeneration vertical pipe G24;

the regenerator G10 and the settler D10 are arranged in parallel, the downlink reaction system is arranged in parallel with the regenerator G10, the outlet of the riser reactor R10 is communicated with a sedimentation cyclone separator D11 in the settler D10, and the outlet of the downlink reactor R20 is also communicated with a gas-solid separator in a settler D20 of the downlink reaction system; the stripping section S10 is arranged below the settler D10, and a stripping component S11 is arranged in the stripping section S10; the lower part of the stripping section S10 is communicated with a regenerator G10 through a spent riser S12 through a spent agent inlet G12A, and a spent agent slide valve VD1 is arranged on the spent riser S12; the downstream reaction system stripping section S20 is arranged below the downstream reaction system settler D20, and a stripping component is arranged in the downstream reaction system stripping section S20; the lower part of the stripping section S20 of the downlink reaction system is communicated with a regenerator G10 through a spent catalyst conveying pipe S22, and a spent catalyst sliding valve is arranged on the spent catalyst conveying pipe S22;

the riser reactor regenerant inlet R14A at the lower part of the riser reactor R10 is communicated with the first regenerant outlet G14A of the regenerator G10 through a first regeneration vertical pipe G14, and a regeneration slide valve VG1 is arranged on the first regeneration vertical pipe G14; a riser catalyst lifting gas inlet R11A is arranged at the bottom of the riser reactor R10 to introduce a riser catalyst lifting gas R11; a crude oil inlet R12A is arranged at the lower part of the riser reactor R10, and steam R15 enters the riser reactor R10; riser reactor reaction product R14 flows out of riser reactor reaction product outlet D12A at the top of settler D10; the reaction product R24 of the downlink reactor flows out from the upper part of a settler D20 of the downlink reaction system, a regenerated catalyst distributor D1 is arranged at the top of the downlink reactor R20, a regenerated catalyst inlet is arranged at the top of the regenerated catalyst distributor D1, and the regenerated catalyst firstly enters the regenerated catalyst distributor D1 and then enters the downlink reactor R20;

in specific implementation, as shown in fig. 1, steam, C4 and/or naphtha light hydrocarbon component R16 are added into the material flow of the reaction product R14 of the riser reactor, wherein the steam addition amount is 5% -50% of the reaction product R14 of the riser reactor;

in the concrete implementation, the regenerator G10 adopts a coke-burning tank rapid fluidized bed and dense-phase fluidized bed regeneration mode, and the catalyst introduced into the riser reactor R10 is led out from a dense-phase fluidized bed regeneration zone G12 at the upper part of the regenerator G10; a regenerator cyclone separator G16 is arranged in a regenerator dilute phase zone G15 of the regenerator G10, the burnt flue gas G17 is discharged from a flue gas outlet G17A at the top of the regenerator G10, catalyst regeneration gas G11 is introduced from a regeneration gas inlet G11A at the bottom of the regenerator G10, fuel G18 is supplemented in a dense phase fluidized bed regeneration zone G12 at the upper part, fuel oil A G is supplemented in a regenerator burnt zone G19 at the lower part, and heat supplementing of the regenerator is realized; the top of the settler D10 is provided with a riser reactor reaction product outlet D12A for leading out a riser reactor reaction product R14; in specific implementation, the heavy petroleum hydrocarbon or heavy cycle oil R19 can be supplemented before the outlet of the riser reactor R10, the heavy petroleum hydrocarbon or heavy cycle oil AS19 can be supplemented in the stripping section S10, the heavy petroleum hydrocarbon or heavy cycle oil BS29 can be supplemented in the stripping section S20 of the downstream reaction system, and the heavy petroleum hydrocarbon or heavy cycle oil can be supplemented before the outlet of the downstream reactor R20, and the heavy petroleum hydrocarbon or heavy cycle oil supplemented in the above parts can be the same or different heavy oil or heavy cycle oil or fuel oil, so that the coke formation amount on the catalyst can be increased.

The method for preparing low-carbon olefin by catalytic conversion of crude oil in the embodiment comprises the following specific process flows:

(1) After the crude oil F0 is heated, the crude oil enters a riser reactor reaction zone R17 of a riser reactor R10, and catalytic cracking reaction is carried out under the catalyst environment introduced from a regenerator G10 through a first regeneration vertical pipe G14; the reaction temperature of the reaction zone R17 of the riser reactor is 550-670 ℃, the reaction time is 0.5-3.0 s, and the reaction pressure gauge pressure is 0.10-0.20 Mpa;

(2) Feeding the material flow after the reaction of the riser reactor R10 into a settler D10 for gas-solid separation to obtain a riser reactor reaction product R14, and feeding the separated catalyst into a regenerator G10 for regeneration after the steam stripping of a steam stripping section S10 for recycling; the reaction product R14 of the riser reactor continuously enters a downlink reactor R20 for reaction, the material flow after the reaction of the downlink reactor R20 is subjected to gas-solid separation in a downlink reaction system settler D20, the catalyst is separated, the reaction product R24 of the downlink reactor is obtained, and the separated catalyst enters a regenerator G10 for regeneration after being stripped in a stripping section S20 of the downlink reaction system for recycling.

In the specific implementation, steam is added into a reaction product R14 of the riser reactor and then enters a downlink reactor R20, so that the partial pressure of the reacted hydrocarbon is reduced, and the yield of the low-carbon olefin is increased; c4 and/or naphtha light hydrocarbon component R16 enter a downlink reactor R20 to react at the same time or react in a separate downlink reactor; regenerated catalyst from the regenerator G10 introduced via a second regeneration riser G24 provides catalyst and heat to the downgoing reactor R20, and the reaction temperature in the downgoing reactor R20 is 650-720 ℃ and the reaction time is 0.1 seconds to 1.5 seconds.

Example 1

Using the device shown in figure 1, preparing low-carbon olefin by catalytic conversion of crude oil;

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

The temperature of crude oil is 135 ℃, and the crude oil is heated to 360 ℃ by heat exchange with the reaction product of a downstream reactor;

a riser reactor and a downlink reactor are arranged;

riser reactor reaction conditions:

the reaction temperature in the reaction zone is 620 ℃ and the reaction time is 1.2 seconds; atomized steam accounts for 10% of the crude oil weight; the total steam amount of the riser reactor is 35% of the heavy components of crude oil;

reaction conditions of the downlink reactor:

injecting steam and recycling C4, wherein the steam of the lower reactor is 50% of crude oil, and the recycling C4 is 7% of crude oil; the reaction time is 0.4 seconds, and the reaction temperature is 700 ℃;

a regenerator: the dense phase fluidized bed zone is replenished with fuel oil, and the fuel oil quantity is controlled according to the regeneration temperature of 760 ℃.

The pressure of the reaction settler D10 is 120kpa (gauge); the slurry oil enters the stripping section to increase the coke making, which accounts for 4% of the crude oil.

Example 1 the product distribution is shown in table 1.

Table 1 example 1 product distribution

Component (A)	Unit (weight)
		Dry gas	37
Methane	8.6
		Ethylene	24.2
Liquefied gas	32
		Propylene	17.2
Gasoline component	13.8
		Circulating oil	9.4
Coke	7.8

Claims

1. A method for preparing low-carbon olefin by catalytic conversion of crude oil is characterized in that after desalted and dehydrated crude oil (F0) is preheated in a heating furnace or a heat exchanger (A0), catalytic cracking is carried out in a device for preparing low-carbon olefin by catalytic conversion to prepare low-carbon olefin; the device for preparing the low-carbon olefin through catalytic conversion is provided with a riser reactor (R10), a downlink reactor (R20) and a catalyst regenerator (G10); the specific process is as follows:

(1) Heating desalted and dehydrated crude oil (F0) through a heating furnace or a heat exchanger (A0) and then atomizing with steam to form a riser reactor reaction raw material flow (R12), or mixing the desalted and dehydrated crude oil with steam before heating, and then forming the riser reactor reaction raw material flow (R12) after atomizing with steam, and entering a riser reactor (R10) to perform catalytic cracking conversion; regenerated catalyst from regenerator (G10) enters riser reactor (R10) from riser reactor regenerator inlet (R14A), providing catalyst environment and heat; carrying out gas-solid separation on the reacted material flow in a settler (D10), and enabling a gas riser reactor reaction product (R14) after the catalyst is separated to flow out of the settler (D10); the separated catalyst is settled to a stripping section (S10) below, the stripped catalyst enters a regenerator (G10) for regeneration, and the regenerated catalyst enters a riser reactor (R10) for recycling;

(2) The reaction product (R14) of the riser reactor after separating the catalyst enters a downlink reactor (R20) for catalytic cracking reaction, the regenerated catalyst from a regenerator (G10) enters the downlink reactor (R20) from the top, the reaction product (R24) of the downlink reactor flows downwards out of the downlink reactor (R20) and flows out of a settler (D20) of a downlink reaction system after being separated from the catalyst, the separated catalyst is stripped in a stripping section (S20) of the downlink reaction system, the stripped catalyst enters the regenerator (G10) from a to-be-regenerated catalyst conveying pipe (S22) for regeneration, and the regenerated catalyst enters the downlink reactor (R20) for recycling.

2. The method for producing light olefins by catalytic conversion of crude oil according to claim 1, wherein C4 and/or light hydrocarbon component (R16) is reacted in a downstream reactor; either the C4 and/or light hydrocarbon component (R16) and the riser reactor reaction product (R14) are respectively reacted in a common downlink reactor (R20), or the C4 and/or light hydrocarbon component (R16) is firstly mixed with the riser reactor reaction product (R14) and then enters the downlink reactor (R20) for reaction, or the C4 and/or light hydrocarbon component (R16) is reacted in an independent downlink reactor; the regenerated catalyst is provided from separate regeneration risers or from a common regeneration riser as the different component feeds react in different downgoing reactors.

3. The method for producing light olefins by catalytic conversion of crude oil according to claim 2, wherein light hydrocarbon component (R16) having an external boiling point lower than 360 ℃ is reacted in a downstream reactor; or the light hydrocarbon component (R16) reacts with the riser reactor reaction product (R14) in a common downlink reactor (R20), or the light hydrocarbon component (R16) reacts with the riser reactor reaction product (R14) in the same downlink reactor (R20) after being mixed, or the light hydrocarbon component (R16) reacts in an independent downlink reactor.

4. The process for the catalytic conversion of crude oil to lower olefins according to claim 1 or 2, characterized in that heavy oil or heavy cycle oil or fuel oil is supplemented at a single or multiple locations before the riser reactor (R10) outlet, before the downgoing reactor outlet, the stripping section (S10), the downgoing reaction system stripping section (S20).

5. The method for preparing low-carbon olefin by catalytic conversion of crude oil according to claim 1, wherein the reaction pressure gauge pressure of the riser reactor (R10) is 0.10-0.20 Mpa, the reaction outlet temperature is 550-670 ℃, and the reaction time is 1.0-3.0 seconds; the reaction temperature of the downlink reactor is 620-720 ℃, and the reaction time is 0.1-1.5 seconds.

6. A device for preparing low-carbon olefin by catalytic conversion of crude oil is characterized in that:

a reaction system and a catalyst regeneration system are arranged at the downstream of the heating furnace or the heat exchanger (A0);

the reaction system is provided with a riser reactor (R10), a settler (D10) and a stripping section (S10), a downlink reactor (R20), a downlink reaction system settler (D20) and a downlink reaction system stripping section (S20); the catalyst regeneration system is provided with a regenerator (G10);

the riser reactor (R10) comprises a riser reactor reaction zone (R17); a riser reactor regenerant inlet (R14A) in the lower part of the riser reactor reaction zone (R17) communicates with a first regenerant outlet (G14A) of the regenerator (G10) via a first regeneration riser (G14); a crude oil inlet (R12A) is arranged at the lower part of the riser reactor (R10), and the crude oil inlet (R12A) is communicated with the heating furnace or the heat exchanger (A0); a downlink reaction raw material inlet is arranged at the top of the downlink reactor (R20), and is communicated with a riser reactor reaction product outlet (D12A) arranged at the top of the settler (D10);

the upper part of the descending reactor (R20) is provided with a regenerated catalyst inlet which is communicated with the regenerator (G10) through a second regenerated vertical pipe (G24); the lower outlet of the descending reactor (R20) is connected with a gas-solid separator in a descending reaction system settler (D20); the stripping section (S20) of the downlink reaction system is arranged below the settler (D20) of the downlink reaction system.

7. The apparatus for producing light olefins by catalytic conversion of crude oil as claimed in claim 6, further comprising a plurality of downgoing reactors arranged in parallel with the downgoing reactor (R20), wherein the feed inlet at the top of each downgoing reactor is in communication with a different feed line.

8. The apparatus for producing light olefins by catalytic conversion of crude oil according to claim 6 or 7, wherein a regenerated catalyst distributor is disposed at the top of the downstream reactor, and the regenerated catalyst inlet is disposed at the top of the regenerated catalyst distributor.