CN114717021A

CN114717021A - Method and reaction device for preparing olefin and aromatic hydrocarbon through catalytic cracking

Info

Publication number: CN114717021A
Application number: CN202210354015.2A
Authority: CN
Inventors: 李荻; 郭江伟; 李雪礼; 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: 2022-04-12
Filing date: 2022-04-12
Publication date: 2022-07-08

Abstract

The invention belongs to the technical field of catalytic conversion of hydrocarbon reaction raw materials, and particularly relates to a method for preparing olefin and aromatic hydrocarbon by catalytic cracking.

Description

Method and reaction device for preparing olefin and aromatic hydrocarbon through catalytic cracking

Technical Field

The invention belongs to the technical field of catalytic conversion of hydrocarbon reaction raw materials, and particularly relates to a method for preparing olefin and aromatic hydrocarbon through catalytic cracking.

Background

The low-carbon olefin represented by ethylene and propylene is the most basic raw material in chemical industry, and the existing catalytic conversion technology is used for producing gasoline and diesel oil and simultaneously producing the low-carbon olefin as a byproduct, so that the requirement of the current market on organic chemical raw materials can not be met. Aromatic hydrocarbon is an important organic chemical raw material with the yield and the scale second only to ethylene and propylene, and derivatives thereof are widely used for producing chemical products such as chemical fibers, plastics, rubber and the like and fine chemicals, and with the continuous development of petrochemical industry and textile industry, the demand of aromatic hydrocarbon in the world is continuously increased. Natural gas or light petroleum fractions are mostly used as raw materials 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 basic raw materials such as olefin, aromatic hydrocarbon and the like are produced as byproducts during the production of ethylene. Although the steam cracking technology is developed for decades and the technology is continuously improved, the steam cracking technology still has the advantages of high energy consumption, high production cost and CO₂The discharge amount is large, the product structure is not easy to adjust, and other technical limitations, and the traditional technology for producing ethylene and propylene by steam cracking is facing a severe test. The method for preparing low-carbon olefin by using catalytic conversion method, and simultaneously by-producing low-carbon olefin such as propylene, butylene and the like and chemical raw materials such as aromatic hydrocarbon and the like is a new direction for solving the problems of resource shortage and low-cost production of chemical products, and has become an important research topic and a hotspot problem at present.

The DCC technology which uses heavy oil as a raw material and propylene as a target product is developed by China petrochemical engineering scientific research institute in the last 90 th century. The technology adopts a riser and turbulent fluidized bed layer series reactor, and the heavy oil is catalyzed to prepare propylene under the conditions of weight hourly space velocity 4(1/H) -6(1/H) gas-solid fluidization. The reinforced catalytic cracking technology (DCC-PLUS) adopting a novel combined reactor system is developed by the stone institute on the basis of the DCC process, the technology is the same as the DCC process in that a riser reactor and a fluidized bed reactor are adopted, and the difference is that the DCC-PLUS process is additionally provided with a light gasoline and a C4 refining riser, and the light gasoline and the material flow after the reaction of C4 are introduced into the fluidized bed reactor. The DCC or DCC-PLUS divides the raw oil reaction into a riser and a fluidized bed layer reaction; however, DCC and DCC-PLUS control the reaction temperature of the fluidized bed zone through the regeneration dosage entering the raw oil riser reaction zone, i.e. the whole reaction process is controlled according to the conditions of the fluidized bed catalytic cracking reaction zone, so that the catalytic cracking conditions of the riser reaction zone, i.e. the heavy oil reaction zone are inevitably deviated from the ideal raw oil catalytic cracking reaction conditions, especially the thermal reaction is increased; in addition, the airspeed of the bed reaction zone of the fluidized bed with fixed raw material amount can only be controlled by the change of the material level of the catalyst in the bed of the fluidized bed; due to the requirements of catalyst carrying and gas-solid separation, a dilute phase space is arranged between a fluidized bed layer reaction zone and a gas-solid separator, a large amount of catalyst is still carried when oil gas leaves the fluidized bed layer, the residence time of the oil gas leaving the fluidized bed layer to the gas-solid separator is more than 20 seconds, the carrying of the catalyst above the catalyst material level and the residence time of the oil gas inevitably cause further side reaction stop when the fluidized bed layer is adopted for reaction, the propylene is further thermally cracked, the product distribution and the propylene selectivity are influenced, the reaction is difficult to terminate in time, the catalytic cracking reaction is inevitably limited, the thermal reaction is increased, the propylene selectivity is greatly reduced, and the dry gas and coke yield is higher.

The prior art focuses on producing propylene and is divided into two types, wherein the first type is a riser and fluidized bed series type reaction, and the second type is a double-riser parallel type reaction. Researchers believe that propylene in the heavy oil catalytic cracking reaction process is indirectly generated by secondary cracking of a gasoline fraction generated by primary cracking of heavy hydrocarbons, and C5-C8 olefin in the gasoline fraction is a main precursor of the propylene. The prior art has many common features, all of which are operated at higher reaction temperatures, catalyst-to-oil ratios and steam injection levels than conventional FCC processes to increase the cracking severity and propylene selectivity.

Disclosure of Invention

The invention aims to provide a method for preparing olefin and aromatic hydrocarbon by catalytic cracking on the basis of the prior art, which is characterized in that raw oil of a component or a heavy component with high real boiling point is subjected to two-stage catalytic cracking in a first reactor and a second reactor in sequence, different raw materials are subjected to catalytic cracking in the two reactors according to different conditions, the gas of a catalytic cracking product of the first reactor continuously enters the second reactor to perform catalytic cracking reaction, a catalyst reacted in the second reactor is relayed to enter the first reactor to continuously participate in the catalytic cracking of the first reactor, the first reactor and the second reactor respectively adopt different fluidized reaction modes according to the raw materials, and the optimization and the respective control of different molecular stage conditions are realized by the staged cracking of the raw oil; thereby realizing the environmental optimization of the catalyst, having better selectivity of reaction products and obviously increasing the proportion of propylene.

The invention provides a method for preparing olefin and aromatic hydrocarbon by catalytic cracking, which adopts the following technical scheme:

carrying out two-stage catalytic cracking on the component with high actual boiling point or heavy component reaction raw oil in a first reactor and a second reactor in sequence; the method comprises the following specific processes:

(1) raw oil enters a first reactor after being atomized by steam, or raw oil is firstly subjected to hydrotreatment or/and partial aromatic hydrocarbon separation and then enters the first reactor after being atomized by steam; the catalyst enters a first reactor from a catalyst inclined tube below a raw oil inlet, catalyst conveying steam enters the first reactor from below the raw oil inlet or below a catalyst inlet, the catalyst is conveyed upwards to contact with raw oil, and the raw oil is subjected to primary catalytic cracking in the first reactor;

(2) the product material flow after the reaction of the first reactor enters a reaction settler A from the outlet of the reactor and is subjected to gas-solid separation through a settler gas-solid separator A, the reaction product gas material flow after the catalyst is separated, namely the product gas of the first reactor is sent out from the reaction settler A and enters a second-stage reactor for continuous reaction, the catalyst from a regenerator enters the second-stage reactor from a regenerated catalyst inclined tube A at the bottom or a lower cracking zone of the second-stage reactor, the steam A enters the second-stage reactor from the bottom of the reactor, and the second-stage catalytic cracking reaction of the product gas of the first reactor is realized in the second-stage reactor, namely the second-stage catalytic cracking reaction of the reacted raw oil is realized; the catalyst separated from the precipitator gas-solid separator A is precipitated to a catalyst stripper A at the lower part, and enters a regenerator from a catalyst to be regenerated inclined pipe for regeneration after being stripped by stripping steam A, and the catalyst is recycled; in specific implementation, preferably, the outlet of the first reactor adopts a first-stage or a cyclone separator as a precipitator gas-solid separator A for gas-solid separation; in the invention, the second-stage reactor is defined according to the cracking sequence without limiting the number of actual reactors, and is provided with one or more reactors; the arrangement of a plurality of parallel reactors is a measure which is easy to implement;

(3) the reaction material flow of the second stage reactor comprises a catalyst, a reaction product and steam, wherein the catalyst, the reaction product and the steam enter a precipitator gas-solid separator of a reaction precipitator from an outlet of the reactor or a product conveying pipe at the upper part of the reactor firstly and then enter a precipitator gas-solid separator of the reaction precipitator from the outlet of the reactor, the two stages of gas-solid separators are usually arranged in series, the gas material flow of the catalyst separated by the precipitator gas-solid separator, namely the cracking product gas of the second stage reactor flows out of the reaction precipitator and is sent out of a reaction device to enter a subsequent treatment system such as product fractionation, the catalyst separated by the precipitator gas-solid separator is precipitated to a catalyst stripper at the lower part and is stripped by using stripping steam, the stripped catalyst enters the first reactor from a spent catalyst conveying pipe and a catalyst inclined pipe, and the catalytic cracking reaction of the raw oil in the first reactor is continuously carried out; or the second-stage reactor is provided with a reactor passing through the reaction settler and the inside of the catalyst stripper, the second-stage reactor is provided with an expanded diameter reaction zone (namely a cracking reaction zone) above or inside the catalyst stripper, the catalyst and the gas in the lower reaction zone upwards enter the cracking reaction zone for continuous cracking, or a porous plate is arranged between the cracking reaction zone and the lower reaction zone, and the catalyst and the gas in the lower reaction zone enter the cracking reaction zone from the porous plate for continuous cracking; the lower part of the shell of the cracking reaction zone is connected with the shell of the catalyst stripper, or the shell of the cracking reaction zone is connected with the lower shell of an external reaction settler; a plurality of catalyst channels are arranged on the periphery of a shell of the pyrolysis reaction zone below an outlet of the reaction zone below the pyrolysis reaction zone or below a porous plate, the catalyst separated by a precipitator gas-solid separator firstly enters a space between the shell of the pyrolysis reaction zone and a shell of a reaction precipitator or a shell of a catalyst stripper, namely a space between the shells, then enters the catalyst stripper through the catalyst channels, and after being stripped by stripping steam in the catalyst stripper, the catalyst enters a first reactor from a conveying pipe for the catalyst to be generated and a catalyst inclined pipe; and the gas in the catalyst stripper upwards flows out of the catalyst stripper, enters the cracking reaction zone from a passage between the outer edge or the outer diameter of the porous plate and the inner diameter of the shell of the cracking reaction zone, or enters the cracking reaction zone from the porous plate A of the passage between the porous plate and the shell of the cracking reaction zone, and then enters the gas-solid separator of the settler together with the reaction product from a product conveying pipe at the upper part of the cracking reaction zone.

In the method for preparing olefin and aromatic hydrocarbon by catalytic cracking, the first reactor is further provided with a regenerated catalyst inclined pipe from the regenerator, and the regenerated catalyst inclined pipe is arranged below the raw oil inlet or above the raw oil inlet so as to introduce the regenerated catalyst from the regenerator.

In order to improve the circulation amount or the reactant oil ratio of the catalyst of the second-stage reactor, a spent catalyst conveying pipe B and a catalyst inclined pipe A are arranged between the catalyst stripper and the second-stage reactor, and part of the catalyst in the catalyst stripper returns to the second-stage reactor from the spent catalyst conveying pipe B and the catalyst inclined pipe A. Preferably, the catalyst inclined tube a is disposed above the reaction raw material inlet or above the regenerated catalyst inclined tube a.

In the invention, the raw oil or the component with high real boiling point or the heavy component is hydrocarbons with the real boiling point higher than 200 ℃ in a mass ratio of more than 90 percent, petroleum hydrocarbons with the real boiling point higher than 250 ℃ in a mass ratio of more than 90 percent are preferably selected, and the raw oil or the component with high real boiling point can be a mixture or a plurality of independent hydrocarbons, or the heavy component or the component with high real boiling point is a hydrotreated raw material or/and a raw material after partial aromatic hydrocarbon is separated; the raw oil can be a mixed component or a plurality of independent components; when the raw oil is a plurality of independent components, part or all of the raw oil can be subjected to hydrotreating or/and separation of part of aromatic hydrocarbon, and then the raw oil enters a first reactor; stratified feed of raw oil is a common practice.

In the method for preparing olefin and aromatic hydrocarbon by catalytic cracking, further, components with a lower actual boiling point relative to the raw oil, namely the reaction raw material with a lower actual boiling point relative to the raw oil, enter a second-stage reactor for catalytic cracking;

the reaction raw material with low relative raw material actual boiling point, gas phase or liquid phase enters a second-stage reactor above or below the regenerated catalyst inclined tube A; the component with low relative raw oil true boiling point or the reaction raw material entering the second-stage reactor is mainly a component with more than 90% of true boiling point lower than 350 ℃ in mass ratio, and preferably a component with more than 90% of true boiling point lower than 300 ℃, the component with low relative raw oil true boiling point is a mixture or a plurality of independent material flows, and the layered feeding of a plurality of components is a common measure; when the reaction raw materials are a plurality of independent components, part or all of the components can be subjected to hydrogenation treatment or aromatic hydrocarbon separation treatment;

in the invention, when the hydrocarbon raw oil is crude oil, components with high true boiling points or heavy components separated from the crude oil are firstly cracked in a first reactor as the raw oil, and light components separated from the crude oil are cracked in a second reactor as reaction raw materials; preferably, the reaction raw material entering the second-stage reactor enters the second-stage reactor below the product gas of the first reactor to perform a catalytic cracking reaction first, that is, the reaction raw material contacts a regenerated catalyst to perform a catalytic cracking reaction first, or the reaction raw material enters an independent reactor of the second-stage reactor to perform a reaction; in specific implementation, the reaction raw materials comprise C5-below carbon number fraction, light gasoline fraction, naphtha fraction, diesel fraction and LCO fraction (light cycle oil or diesel fraction); can be one raw material or a mixture of a plurality of raw materials; or the reaction raw materials are separated or independent multiple different raw materials; (C5 is a hydrocarbon of 5 carbon atoms, C4 is a hydrocarbon of 4 carbon atoms;); further, when the reaction raw materials are a plurality of separated raw materials with different real boiling points, the reaction raw materials preferentially enter a second-stage reactor in a layering manner, and sequentially enter the reactors according to the order of the real boiling points or the number C of molecules, and the raw materials with low real boiling points or the components with less number C preferentially enter the second-stage reactor below for reaction; when the reaction raw material is gas, the gas enters the second-stage reactor preferentially below the regenerated catalyst inclined tube A.

In order to reduce energy consumption and prevent coking of oil gas system equipment behind a reaction settler from influencing the operation of the device, the method of shunting partial catalyst from the second-stage reactor is adopted, and the shunted catalyst enters a catalyst stripper from a catalyst conveying pipe; and the gas and the catalyst after partial catalyst flows out of the second-stage reactor enter a precipitator gas-solid separator in a reaction precipitator through a product conveying pipe above or at the downstream of the second-stage reactor for gas-solid separation, the cracked product gas of the second-stage reactor flows out of the reaction precipitator, and the catalyst is precipitated to a catalyst stripper for steam stripping.

Furthermore, introducing a material flow entering the product conveying pipe into the product conveying pipe, and enabling the material flow entering the product conveying pipe to enter a second-stage reactor after a part of catalyst is shunted out or a product conveying pipe above the catalyst is shunted out, so that the temperature of a reaction material flow entering the product conveying pipe is reduced, and the termination of the material flow reaction in the second-stage reactor and the delayed coke formation and removal are realized; in specific practice, the stream entering the product transport pipe is liquid hydrocarbon or water, and the temperature is lower than 300 ℃.

According to the invention, when recycling is required, for example, non-target chemical products in the product of the method are recycled or other device streams are processed in the device, more than 90% of light hydrocarbons with the boiling point lower than 300 ℃ are preferentially catalytically cracked in the second-stage reactor; the stream with the boiling point higher than 350 ℃ of more than 90 percent is preferentially catalytically cracked in a first reactor;

in specific implementation, when the mixed C4 component, the light gasoline component or the LCO component needs to be remixed, the mixed C4 component, the light gasoline component or the LCO component returns to the second-stage reactor or the first reactor for remixing, and is preferentially remixed in the second-stage reactor 20; the raw oil enters the reactor below the raw oil or below the reaction raw material, and is further preferentially recycled in the second-stage reactor; when part of C4 or light gasoline is recycled in the first reactor, the part of C4 or light gasoline enters the reactor below the raw oil; the light gasoline is preferably selected from components with olefin content of more than 50% or with a true boiling point of less than 100 ℃.

The invention also provides a reaction device for preparing olefin and aromatic hydrocarbon by catalytic cracking, which is provided with two reaction systems, wherein each reaction system is provided with an independent reactor, a reaction settler, a settler gas-solid separator and a catalyst stripper; specifically, the first reaction system comprises a first reactor, a reaction settler A, a settler gas-solid separator A and a catalyst stripper A, the second reaction system comprises a second-stage reactor, a reaction settler, a settler gas-solid separator and a catalyst stripper, and the first reaction system and the second reaction system are arranged in parallel;

a gas conveying pipeline is arranged between the reaction settler A of the first reaction system and the second-stage reactor of the second reaction system, so that reaction product gas of the first reaction system, namely the first-reactor product gas, enters the second-stage reactor of the second reaction system from the gas conveying pipeline to carry out second-stage catalytic cracking reaction;

a catalyst stripper A of the first reaction system is provided with a spent catalyst inclined tube, so that the catalyst after reaction is stripped and enters a regenerator for regeneration from the spent catalyst inclined tube;

a spent catalyst conveying pipe and a catalyst inclined pipe are arranged between the catalyst stripper of the second reaction system and the first reactor of the first reaction system, so that the catalyst reacted in the second reaction system enters the first reactor from the catalyst stripper through the spent catalyst conveying pipe and the catalyst inclined pipe to perform catalytic cracking reaction on the raw oil;

the second-stage reactor is provided with a regenerated catalyst inclined tube A from the regenerator, and the catalyst from the regenerator enters the second-stage reactor from the regenerated catalyst inclined tube A. Settlers, strippers, gas-solid separators, catalyst regenerators are well known to those skilled in the art.

In order to reduce investment, the gas-solid separator A of the settler arranged in the reaction settler A of the first reaction system is one or one stage of cyclone separator arranged at the outlet of the first reactor, so that the gas-solid separation of the material flow at the outlet of the first reactor is carried out through the cyclone separator, namely the gas-solid separation of the product after the reaction of the first reactor is carried out;

in specific implementation, the diameter (inner diameter) of the reaction settler A is designed according to the calculated apparent flow rate of a gas stream corresponding to the outlet of the first reactor and is not lower than 1.5m/s, namely the product gas volume flow of the first reactor is divided by the cross-sectional area of the reaction settler A and is not lower than 1.5 m/s; preferably, the diameter (internal diameter) of the reaction settler A is designed such that the superficial flow velocity calculated for the gas stream at the outlet of the corresponding first reactor is not lower than 2.5m/s to 5.0 m/s;

in specific implementation, the gas-solid separator of the settler of the second reaction system is a two-stage series gas-solid separator, and preferably uses a cyclone separator, or uses a cyclone separator at the first stage and a cyclone separator at the second stage.

In the reaction apparatus for preparing olefin and aromatic hydrocarbon by catalytic cracking, the second-stage reactor is in a riser tube form or a catalyst pneumatic conveying fluidization form, or a gas-solid fast fluidized bed form, or a turbulent fluidized bed form, or two or more different forms of a riser tube, a fast fluidized bed and a turbulent fluidized bed are combined in series to form a combination of different fluidization forms;

when the reaction raw material with the actual boiling point lower than that of the raw oil in the first reaction system enters a second-stage reactor as liquid for catalytic cracking, the second-stage reactor adopts a riser and a fast fluidized bed series connection mode or a riser and a turbulent fluidized bed series connection mode. When the riser and the turbulent fluidized bed are combined in series, the reaction raw materials react in a riser-type reaction zone and then react in a turbulent fluidized bed-type reaction zone;

when the product gas of the first reactor reacts in the second reactor, the second reactor preferentially uses a bottom-up riser and is connected with a fast fluidized bed or a turbulent fluidized bed in series; when the reaction raw material is a gas-phase raw material, the lower cracking zone of the second-stage reactor is preferentially selected to be in a fast fluidized bed form;

in specific implementation, the riser or pneumatic conveying mode is that the average gas flow velocity is more than 5 m/s; the fast fluidized bed is in the form of gas with an average flow velocity of 1.0m/s to 5.0 m/s; the turbulent fluidized bed is in the form of a gas average flow velocity of less than 1.0 m/s.

In the reaction apparatus for preparing olefin and aromatic hydrocarbon by catalytic cracking, the first reactor is further provided with a regenerated catalyst inclined tube from the regenerator, so that the catalyst from the regenerator enters the first reactor from the regenerated catalyst inclined tube. Preferably, the regenerated catalyst inclined tube from the regenerator is arranged above the raw oil inlet, and preferably, the regenerated catalyst inclined tube from the regenerator is arranged above the catalyst inclined tube.

In the reaction apparatus for preparing olefin and aromatic hydrocarbon by catalytic cracking, the second-stage reactor passes through the interior of the reaction settler and the catalyst stripper, or the second-stage reactor, the reaction settler and the catalyst stripper are coaxially arranged, the second-stage reactor is provided with an expanded diameter reaction zone, namely a cracking reaction zone, in the reaction settler or above or in the catalyst stripper, and a reaction stream below the second-stage reactor comprises a catalyst and gas which upwards enter the cracking reaction zone for continuous reaction; a product conveying pipe is arranged above the cracking reaction zone and is connected with the gas-solid separator of the settler;

the lower part of the shell of the cracking reaction zone is hermetically connected with the shell of the catalyst stripper, or the shell of the cracking reaction zone is hermetically connected with the lower shell of an external reaction settler, so that gas in the second-stage reactor is prevented from entering the shell of the reaction settler;

an inter-shell space is formed between the shell of the cracking reaction zone and the shell of the reaction settler, or an inter-shell space is formed between the shell of the cracking reaction zone and the shell of the catalyst stripper; in particular embodiments, steam is supplied to the space between the shells to maintain the catalyst fluidized; in specific implementation, a gas leading-out opening or a channel is arranged on the product conveying pipe, and gas in the space between the hollow shells or in the gas settler enters the product conveying pipe through the gas leading-out opening or the channel;

a porous plate is arranged between the cracking reaction zone and the reaction zone below the cracking reaction zone, and material flow, including a catalyst, a reaction product and steam, of the second-stage reactor below the cracking reaction zone enters the cracking reaction zone through a pore channel of the porous plate; the method comprises the following steps that a plurality of catalyst channels are arranged on the periphery of a shell of a cracking reaction zone below an outlet of the reaction zone below the cracking reaction zone or below a porous plate, and catalyst separated by a precipitator gas-solid separator in a reaction precipitator enters a catalyst stripper from the outside through the catalyst channels; the catalyst is stripped by stripping steam in the stripper and then enters the first reactor for relay use from the spent catalyst conveying pipe and the catalyst inclined pipe;

a channel is reserved between the outer edge or the outer diameter or the periphery of the porous plate and the shell of the cracking reaction zone, gas in the catalyst stripper upwards flows out of the stripper through the channel, enters the cracking reaction zone and then enters a gas-solid separator of the settler together with a reaction product from a product conveying pipe; or further, a porous plate A is arranged on the channel between the outer edge or the outer diameter or the periphery of the porous plate and the shell of the cracking reaction zone, and gas in the catalyst stripper enters the cracking reaction zone from the pore channels or openings on the porous plate A. Or the inner side of the porous plate A is connected with the shell of the cracking reaction zone below the porous plate or connected with the porous plate, and the outer side of the porous plate A is connected with the shell of the cracking reaction zone or connected with the shell of the catalyst stripper or the shell of the reaction settler;

in specific implementation, the flow velocity of gas passing through the perforated plate and the holes on the perforated plate A is not more than 40 m/s;

in particular embodiments, the catalyst stripper may also be disposed around the second stage reactor, or the catalyst stripper may be disposed above and below around and outside the second stage reactor.

In the invention, in order to improve the yield of olefin, in particular to propylene, the first reactor and/or the second reactor inject steam, and the injection amount of the steam is set according to the mass ratio of the steam in each reactor to raw oil or reaction raw material not more than 60 percent; steam addition to the reaction zone is a common practice;

the carbon content of the catalyst from the regenerator is not more than 0.4 percent, and the temperature is not more than 780 ℃; preferably, the carbon content is not more than 0.25%, and the temperature is not more than 760 ℃;

the settler or reactor outlet pressure of the first reaction system is from 100kpa to 300kpa (gauge pressure), the settler or reactor outlet pressure of the second reaction system is from 90kpa to 280kpa (gauge pressure); the reaction temperature of the first reaction system is 450-630 ℃, and the reaction temperature of the second reaction system is 550-680 ℃; the reaction temperature of the reaction raw materials entering the second-stage reactor is 630-720 ℃.

In specific implementation, the catalyst from the regenerator is replaced with the catalyst carrying gas before entering the reactor, so that the amounts of non-condensable gases such as oxygen, CO2, N2 and the like entering the reactor are reduced; catalyst stripping with steam or catalyst carry-over gas displacement with nitrogen.

Has the advantages that:

because the high boiling point component is relatively easy to catalyze and crack, the cracking temperature required by the low boiling point component is higher; the invention adopts a relay two-stage cracking method in two reactors, heavy component macromolecules are firstly catalytically cracked in a first reactor, the macromolecules are cracked into middle and small molecules, and then the medium and small molecules are continuously cracked in a second reactor in a harsher environment after the catalyst is replaced; when raw oil with high true boiling point and reaction raw material with low true boiling point exist at the same time, different reaction environments are adopted for different raw materials, and the efficiency of olefin and aromatic hydrocarbon is improved;

because petroleum hydrocarbon, especially heavy components, are catalytically cracked to prepare ethylene and propylene, the molecular change links are many, the invention realizes the optimization and the respective control of different molecular stage conditions through the staged cracking of the raw oil; the cracking metal content and coke formation of molecules in different stages are greatly different, the environment optimization of the catalyst is realized by the selective use of the catalyst after cracking in different stages, and the selectivity of reaction products is better; the proportion of propylene can be increased in particular markedly by fractional cracking.

Drawings

The drawings are only schematic representations of embodiments of the invention, and are not intended to limit the invention to the particular embodiments described herein.

FIG. 1 is a schematic view of the process scheme of example 1 of the present invention;

FIG. 2 is a schematic view of the process scheme of example 2 of the present invention;

FIG. 3 is a schematic view of a process scheme in example 3 of the present invention;

FIG. 4 is a schematic view of a perforated plate structure provided in the second stage reactor of the present invention;

FIG. 5 is a schematic diagram showing a process scheme for arranging catalyst split flows in a second-stage reactor in example 4 of the present invention;

the numbering marks in the figure are as follows:

10 a first reactor or heavy component reactor, 20 a second reactor or light component reactor; 30 reaction settler, 30A reaction settler a; 40 catalyst stripper, 40A catalyst stripper a;

11 steam, 21 steam a; 16 regeneration slide valve, 26 regeneration slide valve a; 16A catalyst slide valve, 26A catalyst slide valve a; 17 a perforated plate; 19 regenerated catalyst ramps (catalyst ramps from regenerator), 29 regenerated catalyst ramps a; 19A catalyst chute, 29A catalyst chute a; 22 (second stage reactor) lower cracking zone; 24 (second stage reactor) cracking reaction zone, or (second stage reactor) fluidized bed or fast fluidized bed reaction zone; 25 (second stage reactor) product transfer line or zone; 28 shell of the cracking reaction zone; 31 settler gas-solid separator, 31A settler gas-solid separator a; 32 inter-shell spaces, i.e. the space between the cracking reaction zone and the reaction settler shell or the catalyst stripper shell (separated by the cracking reaction zone shell); 33 (on the shell of the cracking reaction zone), i.e. a channel communicating the space between the cracking reaction zone and the shell; 33A dilute phase space; 34 (in the reaction settler and catalyst stripper) gas withdrawal ports or channels; 41 stripper internals, 41A stripper internals a; a spent catalyst conveying pipe 42, a spent catalyst inclined pipe 42A (to the regenerator), and a spent catalyst conveying pipe 42B; 43 catalyst stripper shell; 44 porous plates a, 45 (on porous plate a) channels or openings; 46 catalyst transfer line (de-catalyst stripper), 46A transfer line slide valve;

f11 raw material oil or heavy component raw material oil, or a tower bottom component separated from a hydrocarbon reaction raw material; f22 (entering the second-stage reactor) reaction raw material or light hydrocarbon, and F23 enters the stream of the product conveying pipe; f04 (exiting reaction settler a) first reactor product gas, F06 (exiting reaction settler) second stage reactor cleavage product gas; f41 stripping steam, F42 stripping steam A, F41A catalyst stripper gas, or catalyst stripper gas entering a cracking reaction zone (containing steam and oil gas); d1 is the outer diameter of the perforated plate; d2 is the cleavage reaction zone diameter.

Detailed Description

The technical solutions of the present invention are described below with specific examples, but the scope of the present invention is not limited thereto.

According to the invention, as shown in fig. 1-5, two reaction systems are provided, wherein the first reaction system comprises a first reactor 10, a reaction settler A30A, a settler gas-solid separator A31A and a catalyst stripper A40A, the second reaction system comprises a second-stage reactor 20, a reaction settler 30, a settler gas-solid separator 31 and a catalyst stripper 40, and the first reaction system and the second reaction system are arranged in parallel; a gas conveying pipeline is arranged between the reaction settler A30A and the second-stage reactor 20; the catalyst stripper A40A is provided with a spent catalyst inclined tube 42A; a spent catalyst conveying pipe 42 and a catalyst inclined pipe 19A are arranged between the catalyst stripper 40 and the first reactor 10, and a catalyst slide valve 16A is arranged between the spent catalyst conveying pipe 42 and the catalyst inclined pipe 19A; the second-stage reactor 20 is provided with a regenerated catalyst inclined tube A29 from a regenerator (not shown in the figure), and a regenerated slide valve A is arranged on the regenerated catalyst inclined tube A29;

in specific implementation, according to needs, a regenerated catalyst inclined pipe 19 from a regenerator is arranged in the first reactor 10, the regenerated catalyst inclined pipe 19 is arranged below the raw oil inlet or above the raw oil inlet, and the regenerated catalyst inclined pipe 19 is provided with a regenerated slide valve 16; according to the requirement, a spent catalyst conveying pipe B42B and a catalyst inclined pipe A29A can be arranged between the catalyst stripper 40 and the second-stage reactor 20, and a catalyst slide valve A26A is arranged on the spent catalyst conveying pipe B42B and the catalyst inclined pipe A29A; according to the requirement, the second-stage reactor 20 can pass through the reaction settler 30 and the catalyst stripper 40, an expanded diameter reaction zone, namely a cracking reaction zone 24, is arranged above the catalyst stripper 40 in the second-stage reactor 20, a product conveying pipe 25 is arranged above the cracking reaction zone 24, a porous plate 17 and a corresponding catalyst channel 33 are arranged in the cracking reaction zone 24, or a porous plate A44 is also arranged, so that the gas material flow and the catalyst are conveyed up and down in the reaction process; according to the requirement, a catalyst conveying pipe 46 is arranged between the lower part of the product conveying pipe 25 of the second-stage reactor 20 and the catalyst stripper 40, a part of the catalyst is separated from the second-stage reactor 20 and enters the catalyst stripper 40, and the catalyst conveying pipe 46 is provided with a conveying pipe slide valve 46A; in specific implementation, the corresponding stripper is provided with stripper internals, stripping steam is introduced, corresponding fluidization steam is introduced at different positions according to fluidization requirements, and a settler, the stripper, a gas-solid separator, a catalyst regenerator and other parts which are not described in detail are well known by technical personnel and are not described again;

the specific implementation process is as follows:

in specific implementation, raw oil F11 is heated to 200-350 ℃, steam with 5-10% of the raw oil is atomized and then enters the first reactor 10, and the gas state of the product gas F04 of the first reactor directly enters the second-stage reactor 20 to replace the catalyst and then continues to be cracked;

when a reaction raw material F22 with an actual boiling point lower than that of raw material oil F11 is cracked in a reactor, the reaction raw material F22 enters a second-stage reactor 20 below a first-reactor product gas F04 to be cracked, preferably, the reaction raw material F22 is reacted for 0.5-1.5 seconds and then cracked of a first-reactor product gas F04;

when the mixed C4 is recycled, the mixed C4 is preferentially fed into the lowest part of the second-stage reactor 20, and C4 is preferentially fed into the reactor after being gasified; the reaction feed F22 entering the second stage reactor 20 comprises naphtha, gasoline or diesel components, entering in liquid or gas phase, preferably in gas phase; the steam stripping multi-point entering of the steam stripping device is a common design, the steam stripping amount is designed according to 2.0-3.0kg/(t catalyst), and is a common condition; the settler pressure is preferably in the range of 110kpa to 140 kpa;

the reaction time of the first reactor 10 is preferably set to not more than 1.5 seconds, and the reaction temperature is preferably controlled to not more than 600 ℃;

the total reaction time of the second-stage reactor 20 is preferably designed according to the time not less than 2.0 seconds, and the reaction temperature is preferably controlled according to the temperature of 630-650 ℃;

the catalyst from the regenerator enters the first reactor 10 from the regenerated catalyst inclined tube 19, and preferably, the raw oil F11 enters the first reactor 10 after 0.5-1.5 seconds of reaction time under the catalyst environment entering from the catalyst inclined tube 19A.

Example 1:

adopting the reaction method shown in FIG. 1 to prepare olefin and aromatic hydrocarbon, wherein raw oil F11 is atmospheric heavy oil; properties of feed oil F11: density 0.89, hydrogen content 12.9, temperature 280 ℃; the steam amount of the first reactor is 25% of the raw oil F11, and the steam amount entering the second stage reactor is 30% of the raw oil F11; the catalyst temperature from the regenerator is 720 ℃, and the carbon content is 0.2 percent;

first reaction system conditions:

the first reactor 10 uses a riser reaction mode, the reaction time is 1.2 seconds, the reaction temperature is 580 ℃, and the operation pressure of a reaction settler A30A is 130 kpa; steam 11 is 3 percent of the raw oil F11; the atomized steam of the raw oil F11 is 7 percent of the raw oil F11; stripping steam AF42 is 3% of the raw oil F11; the outlet of the reactor is provided with a first-stage cyclone separator, the inner diameter of the reaction settler A30A calculates the apparent flow velocity of the cross-sectional area according to the product gas F04 of the corresponding first reactor, and the height of the reaction settler A30A above the cyclone separator is 1.0 meter; the catalyst from the catalyst stripper 40 enters the first reactor 10 from the catalyst inclined tube 19A below the raw oil inlet;

second reaction system conditions:

the second-stage reactor 20 adopts a riser reaction mode, the reaction time is 2.5 seconds, the reaction temperature is 650 ℃, and the operating pressure of the reaction settler 30 is 110 kpa; steam A21 is 2% of the raw oil F11; stripping steam F41 is 1.5 percent of the raw oil F11; the inner diameter of the reaction settler 30 calculates the apparent flow velocity of the cross-sectional area of the gas F06 corresponding to the cracked product of the second-stage reactor to be 0.6m/s, and the height of the reaction settler is in accordance with the installation requirement of a two-stage cyclone separator, namely a dipleg; the flow rate of the first reactor product gas oil gas pipeline between the reaction settler A30A and the second stage reactor 20 is 30 m/s; the first reactor product gas F04 enters the second stage reactor 20 above the regenerated catalyst chute a29 from the regenerator; example 1 gas product prediction is shown in table 1.

Table 1 example 1 gas product prediction

Components	Unit% (weight)
		Dry gas	29
Methane	7.8
		Ethylene	17.5
Liquefied gas	55
		Propylene (PA)	23.6

Example 2:

preparing olefin and aromatic hydrocarbon by adopting the method shown in FIG. 2;

the raw oil F11 is a component with high true boiling point separated from Daqing crude oil, and comprises heavy diesel oil and normal pressure heavy oil; the initial boiling point is 220 ℃; the reaction raw material F22, namely light hydrocarbon is a component with low true boiling point separated from Daqing crude oil, and comprises naphtha and light diesel oil, and the final boiling point is 300 ℃; the reaction raw material F22 is in a gas phase state, and the temperature is 287 ℃;

the first reactor 10 adopts a riser form, the reaction temperature is 600 ℃, and the reaction time is 1.1 second; the pressure of the reaction settler A30A is 250 kpa; the flow of the catalyst from the regenerator entering through the regenerated catalyst inclined tube 19 is 9 times of the flow of the raw material oil F11, the catalyst from the regenerator is a regenerant, the temperature is 720 ℃, and the carbon content is 0.02 percent; the total steam amount is controlled according to 25 percent of the raw oil F11, wherein the steam 11 is 3 percent of the raw oil F11, and the atomized steam is 5 percent of the raw oil F11; additional steam to make up steam enters the first reactor 10;

the second-stage reactor 20 adopts a combination form of a fast fluidized bed, a riser and a fast fluidized bed; the lower cracking zone 22 is in the form of a fast fluidized bed, the diameter is designed according to the gas flow rate of 2.5m/s, and the reaction time is 1.0 second; the cracking reaction zone 24 in the middle is a fast fluidized bed reaction zone, the diameter is designed according to the flow rate of 1.8m/s, the reaction time is 2.5 seconds, and the reaction temperature is controlled according to 645 ℃; the catalyst entering from the catalyst inclined tube A29A is designed according to 3 times of the total amount of the raw oil F11 and the reaction raw material F22;

part of the catalyst from the catalyst stripper 40 enters the second stage reactor 20 from the catalyst inclined tube a29A, and the catalyst enters above the regenerated catalyst inclined tube a29 from the regenerator;

the rest is the same as in example 1.

Example 3:

preparing olefin and aromatic hydrocarbon by adopting the method shown in FIG. 3; the reaction raw materials are the same as example 2;

the first reactor 10 is in the form of a riser;

the second-stage reactor 20, the reaction settler 30 and the catalyst stripper 40 are coaxially arranged, the second-stage reactor 20 is provided with an expanded pyrolysis reaction zone 24 above the catalyst stripper 40, and the pyrolysis reaction zone 24 is arranged in the reaction settler 30;

the shell 28 of the cracking reaction zone is connected with the lower shell of an external reaction settler 30; a porous plate 17 is arranged between the cracking reaction zone 24 and the reaction zone below, and the total opening area of the porous plate 17 is 25m/s according to the stripping flow rate; a plurality of catalyst channels 33 are arranged on the circumference of the shell 28 of the cracking reaction zone below the porous plate 17, the catalyst channels 33 are rectangles with the width of 100mm and the height of 300mm, and the number of the catalyst channels is determined according to the flow velocity of the catalyst of 0.5 m/s; a channel is arranged between the shell 28 of the cracking reaction zone and the porous plate 17, and the area of the channel is designed according to the gas flow velocity of 4.0 m/s;

the product conveying pipe material flow F23 introduced from the product conveying pipe 25 above the cracking reaction zone 24 is LCO component from the product fractionating tower, and the flow rate is 5% of the sum of the raw material oil F11 and the reaction raw material F22;

the rest is the same as the embodiment 1;

in particular, as shown in FIG. 4, perforated plate A44 may be provided between perforated plate 17 and cracking reaction zone shell 28, and gas F41A in the catalyst stripper may enter cracking reaction zone 24 through holes or openings 45 in perforated plate A44.

Example 4:

preparing olefins and aromatics by using the method shown in FIG. 5;

after the second-stage reactor reacts, 80% of catalyst is shunted out of the reactor, the shunted catalyst enters a catalyst stripper 40 from a catalyst conveying pipe 46, the rest 20% of catalyst and product gas enter a product conveying pipe 25 above the reactor, and meanwhile, a product conveying pipe material flow F23 is introduced into the product conveying pipe 25, so that the temperature reduction of the second-stage reactor reactant flow is realized; the material flow F23 entering the product conveying pipe is a part of raw material oil F11, or a product with a true boiling point lower than 360 ℃ fractionated from the cracked product gas F06 of the second-stage reactor, or a remixed gasoline component or a remixed LCO component. The rest is the same as in example 1.

Claims

1. A method for preparing olefin and aromatic hydrocarbon by catalytic cracking is characterized in that a component with high real boiling point or heavy component reaction raw oil (F11) is subjected to two-stage catalytic cracking in a first reactor (10) and a second reactor (20) in sequence; the specific process is as follows:

(1) the raw oil (F11) is atomized by steam and then enters the first reactor (10), or the raw oil (F11) is firstly hydrotreated or/and separated from partial aromatic hydrocarbon and then atomized by steam and then enters the first reactor (10); the catalyst enters a first reactor (10) from a catalyst inclined tube (19A) below a raw oil inlet, catalyst conveying steam (11) enters the first reactor (10) from below the raw oil inlet or below a catalyst inlet, and raw oil (F11) is firstly subjected to primary catalytic cracking in the first reactor (10);

(2) the product after the reaction of the first reactor is subjected to gas-solid separation in a reaction settler A (30A) through a settler gas-solid separator A (31A), the gas stream of the reaction product, namely the first reactor product gas (F04), enters a second-stage reactor (20) from the reaction settler A (30A) for continuous reaction, and the catalyst from the regenerator enters the second-stage reactor (20) from a regenerated catalyst inclined tube A (29) at the bottom or a lower cracking zone (22) to realize the second-stage catalytic cracking reaction of the raw oil; the catalyst separated from the gas-solid separator A (31A) of the settler is settled to a catalyst stripper A (40A) at the lower part, and is stripped by stripping steam A (F42) and then enters a regenerator from a spent catalyst inclined tube (42A) for regeneration and recycling;

(3) the reactant flow of the second-stage reactor comprises a catalyst, a reaction product and steam, wherein the catalyst, the reaction product and the steam enter a settler gas-solid separator (31) of a reaction settler (30) from an outlet of the reactor or pass through a product conveying pipe (25) at the upper part of the reactor firstly and then enter a settler gas-solid separator (31) of the reaction settler (30) from the outlet of the reactor, the gas flow separated by the settler gas-solid separator (31), namely second-stage reactor cracking product gas (F06), flows out of the reaction settler (30), the catalyst is settled to a catalyst stripper (40) at the lower part, stripping is carried out by using stripping steam (F41), the stripped catalyst enters a first reactor (10) from a spent catalyst conveying pipe (42) and a catalyst inclined pipe (19A) to carry out catalytic cracking reaction on raw oil (F11);

or the second-stage reactor (20) passes through the reaction settler (30) and the inside of the catalyst stripper (40), an expanded diameter reaction zone, namely a cracking reaction zone (24), is arranged above or in the catalyst stripper (40) of the second-stage reactor (20), the catalyst and the gas in the lower reaction zone upwards enter the cracking reaction zone (24) for continuous cracking, or a porous plate (17) is arranged between the cracking reaction zone (24) and the lower reaction zone, and the catalyst and the gas in the lower reaction zone enter the cracking reaction zone (24) from the porous plate (17) for continuous cracking; the lower part of the shell (28) of the cracking reaction zone (24) is connected with a catalyst stripper shell (43), or the shell (28) of the cracking reaction zone is connected with the lower shell of an external reaction settler (30); a plurality of catalyst channels (33) are arranged on the circumference of a shell (28) of the cracking reaction zone below an outlet of the reaction zone below a cracking reaction zone (24) or below a porous plate (17), a catalyst separated by a precipitator gas-solid separator (31) firstly enters a space between the shell (28) of the cracking reaction zone and a shell of a reaction precipitator or a catalyst stripper, namely a shell space (32), and then enters a catalyst stripper (40) through the catalyst channels (33), and after being stripped by stripping steam (F41) in the catalyst stripper (40), the catalyst enters a first reactor (10) from a spent catalyst conveying pipe (42) and a catalyst inclined pipe (19A); and the gas (F41A) in the catalyst stripper (40) flows upwards out of the catalyst stripper (40), enters the cracking reaction zone (24) from a passage between the outer edge or the outer diameter of the porous plate (17) and the inner diameter of the shell (28) of the cracking reaction zone, or enters the cracking reaction zone (24) from a porous plate A (44) of the passage between the porous plate (17) and the shell (28) of the cracking reaction zone, and then enters the gas-solid separator (31) of the settler from a product conveying pipe (25) at the upper part of the cracking reaction zone (24) together with the reaction product.

2. The method for producing olefins and aromatics by catalytic cracking according to claim 1, wherein: the first reactor (10) is provided with a regenerated catalyst inclined pipe (19) from a regenerator, and the regenerated catalyst inclined pipe (19) is arranged below the raw oil inlet or above the raw oil inlet.

3. The method for producing olefins and aromatics by catalytic cracking according to claim 1, wherein: a spent catalyst conveying pipe B (42B) and a catalyst inclined pipe A (29A) are arranged between the catalyst stripper (40) and the second-stage reactor (20), and part of the catalyst in the catalyst stripper (40) returns to the second-stage reactor (20) from the spent catalyst conveying pipe B (42B) and the catalyst inclined pipe A (29A).

4. The method for producing olefins and aromatics by catalytic cracking according to claim 1, wherein: the reaction raw material (F22) with the boiling point lower than the raw oil real boiling point enters a second-stage reactor (20) for catalytic cracking;

the reaction raw material (F22), gas phase or liquid phase enters the second-stage reactor (20) above or below the regenerated catalyst inclined tube A (29).

5. The method for producing olefins and aromatics by catalytic cracking according to claim 1, wherein: withdrawing a portion of the catalyst from the second stage reactor (20), the withdrawn catalyst passing from a catalyst transfer line (46) to a catalyst stripper (40); and the gas and the catalyst after partial catalyst flow out in the second-stage reactor (20) enter a precipitator gas-solid separator (31) in a reaction precipitator (30) through a product conveying pipe (25) above or downstream the second-stage reactor (20) for gas-solid separation, the cracked product gas (F06) of the second-stage reactor flows out of the reaction precipitator (30), and the catalyst is precipitated in a catalyst stripper (40) for steam stripping.

6. The method for producing olefins and aromatics by catalytic cracking according to claim 1 or 5, wherein: introducing an incoming product transfer line stream (F23) to the product transfer line (25), the incoming product transfer line stream (F23) being liquid hydrocarbons or water at a temperature of less than 300 ℃.

7. The method for producing olefins and aromatics by catalytic cracking according to claim 1, wherein: the component or the heavy component with the high real boiling point is petroleum hydrocarbon with the real boiling point higher than 200 ℃ and the mass ratio of more than 90 percent, or the petroleum hydrocarbon after partial aromatic hydrocarbon is separated.

8. A reaction unit for preparing olefin and aromatic hydrocarbon by catalytic cracking is characterized in that: two reaction systems are arranged, and each reaction system is provided with an independent reactor, a reaction settler, a settler gas-solid separator and a catalyst stripper;

a gas conveying pipeline is arranged between the reaction settler A (30A) of the first reaction system and the second-stage reactor (20) of the second reaction system, so that the reaction product gas of the first reaction system, namely the first-stage reactor product gas (F04), enters the second-stage reactor (20) of the second reaction system from the gas conveying pipeline to carry out second-stage catalytic cracking reaction;

a catalyst stripper A (40A) of the first reaction system is provided with a spent catalyst inclined pipe (42A), so that the catalyst after reaction is stripped and enters a regenerator from the spent catalyst inclined pipe (42A);

a spent catalyst conveying pipe (42) and a catalyst inclined pipe (19A) are arranged between the catalyst stripper (40) of the second reaction system and the first reactor (10) of the first reaction system, so that the catalyst reacted in the second reaction system enters the first reactor (10) from the catalyst stripper (40) through the spent catalyst conveying pipe (42) and the catalyst inclined pipe (19A);

the second stage reactor (20) is provided with a regenerated catalyst inclined tube A (29) from the regenerator.

9. The reactor of claim 8, wherein the catalytic cracking reaction unit comprises:

the gas-solid separator A (31A) of the settler arranged in the reaction settler A (30A) of the first reaction system is a cyclone separator arranged at the outlet of the first reactor (10) so as to carry out gas-solid separation on material flow at the outlet of the first reactor through the cyclone separator.

10. The reactor of claim 8, wherein the catalytic cracking reaction unit comprises: the second-stage reactor (20) is in a riser tube form, or a rapid fluidized bed or a turbulent fluidized bed form, or is combined in series in different forms in a riser tube, a rapid fluidized bed and a turbulent fluidized bed;

when the reaction raw material (F22) with the boiling point lower than the raw material oil actual boiling point of the first reaction system enters the second-stage reactor (20) as liquid for catalytic cracking, the second-stage reactor (20) adopts a riser and fast fluidized bed series connection mode or a riser and turbulent fluidized bed series connection mode.

11. The reaction unit of claim 8 for producing olefins and aromatics by catalytic cracking, wherein: the first reactor (10) is provided with a regenerated catalyst inclined pipe (19) from a regenerator.