阅读说明：本技术 一种生产低碳烯烃和芳烃的方法 (Method for producing low-carbon olefin and aromatic hydrocarbon ) 是由 杨超 朱根权 李红波 马文明 沙有鑫 成晓洁 于 2019-10-25 设计创作，主要内容包括：本发明涉及石油加工领域,公开了一种生产低碳烯烃和芳烃的方法,包括：(1)将催化剂自第一反应器上部引入,新鲜原料油自第一反应器底部引入,催化剂和新鲜原料油在第一反应器中逆流接触进行裂化反应,得到第一反应油气和第一反应后催化剂；(2)回炼物流自第二反应器底部引入与第一反应后催化剂接触进行裂化反应,得到第二反应油气和第二反应后催化剂；(3)将第二反应后催化剂进行汽提和再生,并将得到的再生催化剂引入所述第一反应器中循环利用。本发明提供的方法简单易行,且在催化裂化反应过程中提高低碳烯烃和芳烃的选择性,降低干气和焦炭产率。(The invention relates to the field of petroleum processing, and discloses a method for producing low-carbon olefin and aromatic hydrocarbon, which comprises the following steps: (1) introducing a catalyst from the upper part of a first reactor, introducing fresh raw oil from the bottom of the first reactor, and carrying out a cracking reaction by countercurrent contact of the catalyst and the fresh raw oil in the first reactor to obtain a first reaction oil gas and a first post-reaction catalyst; (2) introducing the recycle material flow from the bottom of the second reactor to contact with the first reacted catalyst for cracking reaction to obtain second reacted oil gas and a second reacted catalyst; (3) and (3) stripping and regenerating the catalyst after the second reaction, and introducing the obtained regenerated catalyst into the first reactor for recycling. The method provided by the invention is simple and easy to implement, the selectivity of the low-carbon olefin and the aromatic hydrocarbon is improved in the catalytic cracking reaction process, and the yield of dry gas and coke is reduced.)

1. A process for producing lower olefins and aromatics, the process comprising:

(1) introducing a catalyst from the upper part of a first reactor, introducing fresh raw oil from the bottom of the first reactor, and carrying out a cracking reaction by countercurrent contact of the catalyst and the fresh raw oil in the first reactor to obtain a first reaction oil gas and a first post-reaction catalyst;

(2) introducing the recycle material flow from the bottom of the second reactor to contact with the first reacted catalyst for cracking reaction to obtain second reacted oil gas and a second reacted catalyst;

(3) and (3) stripping and regenerating the catalyst after the second reaction, and introducing the obtained regenerated catalyst into the first reactor for recycling.

2. The method according to claim 1, wherein the first reactor is a dilute phase transport bed reactor, preferably, the average void ratio of the solid during the transport of the dilute phase in the first reactor is above 0.8, more preferably 0.8-0.9;

preferably, the first reactor is a straight pipe with equal diameter or variable diameter, or a curved pipe with equal diameter or variable diameter;

the second reactor is a dense-phase fluidized bed reactor, and preferably, the average void volume of solids in the second reactor is less than 0.6, and more preferably, 0.4 to 0.6.

3. The process of claim 1, wherein the catalyst comprises an active component and an inert component;

preferably, the catalyst is spherical, and the active component is wrapped outside the inert component;

more preferably, the catalyst has an average particle size of 70 μm to 2mm, more preferably 100 μm to 1 mm.

4. The method of claim 3, wherein the mass ratio of the inert component to the active component is 1-10: 1, preferably 3 to 7: 1;

preferably, the active components comprise zeolite, inorganic oxide and optional clay, and further preferably, the content of the zeolite is 1-60 wt%, the content of the inorganic oxide is 5-99 wt% and the content of the clay is 0-70 wt% based on the total weight of the active components; more preferably, the zeolite is selected from at least one of Y or HY type zeolite with or without rare earth, ultrastable Y type zeolite with or without rare earth, ZSM-5 series zeolite, high silica zeolite having a pentasil structure, and beta zeolite;

preferably, the inert component is selected from the group consisting of iron, copper, cobalt, nickel and SiO₂At least one of (1).

5. The process according to claim 1, wherein the mass ratio of the recycle stream to the fresh feed oil is 0.1-0.5: 1, preferably 0.15 to 0.3: 1.

6. the method of claim 1, wherein,

the reaction conditions of the first reactor include: the fresh raw oil inlet temperature is 560-650 ℃, preferably 580-630 ℃, the oil gas residence time is 0.2-5 seconds, preferably 0.5-3 seconds, and the weight ratio of the oil to the solvent is 1-50, preferably 10-30;

the reaction conditions of the second reactor include: the recycle stream inlet temperature is 550-650 ℃, preferably 580-630 ℃, and the oil gas residence time is 3-20 seconds, preferably 5-15 seconds.

7. The method according to any one of claims 1-6, wherein the fresh raw oil is a petroleum hydrocarbon and/or a mineral oil;

wherein the petroleum hydrocarbon is selected from at least one of vacuum gas oil, atmospheric gas oil, coker gas oil, deasphalted oil, vacuum residue, atmospheric residue, and hydrogenated heavy oil;

wherein the mineral oil is selected from at least one of coal liquefaction oil, oil sand oil, shale oil, synthetic oil, and partial fraction or whole fraction of animal and vegetable oil and fat.

8. The method of any one of claims 1-6, wherein the recycle stream is selected from naphtha fractions and/or diesel light fractions in the second reaction hydrocarbon;

preferably, the recycle stream is selected from naphtha fraction with the distillation range of 40-205 ℃ in the second reaction oil gas and/or diesel oil light fraction with the distillation range of 205-335 ℃ in the second reaction oil gas.

9. The method according to any one of claims 1 to 8, wherein the method further comprises introducing the regenerated catalyst obtained in step (3) into the second reactor for recycling.

10. The process according to claim 9, wherein in the second reactor, the mass ratio of the introduced amount of the regenerated catalyst to the introduced amount of the catalyst after the first reaction is from 0.1 to 0.5: 1.

Technical Field

The invention relates to the field of petroleum processing, in particular to a method for producing low-carbon olefin and aromatic hydrocarbon.

Background

From the production conditions of gasoline and diesel oil in China in recent years, the yield of gasoline and diesel oil in China, particularly the gasoline yield, keeps continuously increasing, but the apparent consumption of gasoline falls back from 2016, and the apparent consumption of diesel oil is continuously reduced. And ten million-ton-level large refineries are put into production in the next five years, and the excess of oil refining capacity leads to more intense industry competition, thereby bringing about the problems of insufficient operation, reduced profitability and the like. However, the chemical industry market counts that the domestic chemical raw materials such as olefin and aromatic hydrocarbon are still in shortage, and the transformation of oil refining enterprises from fuel type to chemical type is in the trend.

The catalytic cracking technology is an important crude oil secondary processing technology, has the characteristics of wide raw material adaptability, high heavy oil conversion rate, flexible product scheme and the like, and has an irreplaceable position in the aspect of producing light oil products and low-carbon olefins. In view of the current development and development trend of catalytic cracking technology for producing chemical raw materials in recent years, research is mainly carried out on the aspects of improving reaction severity, using a catalyst or an auxiliary agent containing a shape-selective molecular sieve, using a novel reactor structure, recycling a fraction rich in a propylene precursor and the like.

CN102899078A discloses a catalytic cracking method for producing propylene, which is based on a combined reactor composed of a double riser and a fluidized bed, and comprises the steps of firstly introducing heavy raw oil and a first strand of catalyst into a first riser reactor for reaction, and separating the oil and then introducing the oil into a separation system. Introducing the cracked heavy oil into a second riser reactor to contact and react with the catalyst introduced into the second riser reactor, introducing light hydrocarbon into the second riser reactor to contact with a mixture formed by the contact and reaction of the cracked heavy oil and a second strand of cracking catalyst, wherein the light hydrocarbon comprises C4 hydrocarbon or gasoline fraction obtained by a product separation system. And then introducing the oil gas reacted by the second riser reactor and a catalyst into the fluidized bed reactor for reaction. Through the optimization of the process scheme, the proper catalyst is prepared, the selective conversion is carried out on different feeds, and the yield of propylene and butylene is higher.

CN101531923A discloses a catalytic conversion method for preparing propylene and high-octane gasoline, which considers oil slurry, diesel oil, gasoline and hydrocarbons with 4-8 carbon atoms as raw materials which are difficult to crack, and vacuum gas oil, atmospheric gas oil, coking gas oil, deasphalted oil, vacuum residual oil, atmospheric residual oil and hydrogenated heavy oil are easy-cracking raw materials. The method contacts the raw material difficult to crack with the thermal regeneration catalytic cracking catalyst, and the reaction temperature is 600-750 ℃, the weight hourly space velocity is 100-800h^-1The cracking reaction is carried out under the condition that the reactant flow is mixed with the raw oil easy to crack, the reaction temperature is 450 ℃ and 620 ℃, and the weight hourly space velocity is 0.1-100h^-1The cracking reaction is carried out under the conditions of (1).

CN101579612A discloses a dense-phase fluidized bed reactor and a method for preparing olefins and aromatics by catalytic reaction, wherein the method employs a dense-phase fluidized bed reactor, in which a catalyst flows downward along the direction of gravity, and a reaction raw material flows upward, and passes through a catalyst bed layer to perform catalytic cracking reaction.

W02013/188729Al discloses a process for the conversion of crude oil whole cuts to hydrocarbon products by catalytic cracking using a moving bed reactor with a temperature profile having more than one fixed temperature zone along the operating length of the moving bed reactor. The temperature gradient is fixed and constant along the operating length of the moving bed reactor, with the lowest temperature of the temperature gradient being at the feed position of the moving bed reactor. The method can be used for obtaining low-carbon olefin and C6-C8 aromatic hydrocarbon.

The method has certain effect on the aspect of process design of producing the low-carbon olefin by catalytic cracking, but when the method is adopted, a large amount of dry gas and coke are inevitably produced while the low-carbon olefin is produced. Therefore, further intensive research is needed to improve the selectivity of lower olefins while reducing the dry gas and coke yields.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide a method for producing low-carbon olefin and aromatic hydrocarbon.

In order to achieve the above object, the present invention provides a method for producing lower olefins and aromatic hydrocarbons, the method comprising:

(1) introducing a catalyst from the upper part of a first reactor, introducing fresh raw oil from the bottom of the first reactor, and carrying out a cracking reaction by countercurrent contact of the catalyst and the fresh raw oil in the first reactor to obtain a first reaction oil gas and a first post-reaction catalyst;

(2) introducing the recycle material flow from the bottom of the second reactor to contact with the first reacted catalyst for cracking reaction to obtain second reacted oil gas and a second reacted catalyst;

(3) and (3) stripping and regenerating the catalyst after the second reaction, and introducing the obtained regenerated catalyst into the first reactor for recycling.

Preferably, the first reactor is a dilute phase transport bed reactor.

Preferably, the second reactor is a dense phase fluidized bed reactor.

Preferably, the catalyst contains an active component and an inert component; further preferably, the catalyst is spherical and the active component is coated on the outside of the inert component.

Preferably, the catalyst has an average particle size of from 70 μm to 2mm, more preferably from 100 μm to 1 mm.

The method provided by the invention adopts the mode that the catalyst is adopted in the first reactor from top to bottom along with gravity, and the fresh raw oil is subjected to countercurrent contact cracking from bottom to top, and the recycle material flow injected from the bottom is adopted in the second reactor to be contacted with the catalyst after the first reaction to generate a cracking reaction, so that the low-carbon olefin and aromatic hydrocarbon products are produced.

Drawings

FIG. 1 is a schematic flow diagram of one embodiment of the method provided by the present invention.

Description of the reference numerals

1: first reactor 2: second reactor

3: the regenerator 4: regenerated catalyst distributor

5: a stripper 6: pre-lifter

11: fresh raw oil inlet 12: first reaction oil gas outlet

13: catalyst conveying pipe

21: pre-lift medium inlet 22: recycle stream inlet

23: second reaction oil gas outlet 24: spent catalyst inclined tube

31: regeneration air inlet 32: regenerated flue gas outlet

33: first regenerated catalyst inclined tube 34: second regenerated catalyst inclined tube

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In the present invention, the use of directional terms such as "upper, lower, top, bottom" without a contrary intention, generally refers to upper, lower, top, bottom as illustrated in the accompanying drawings.

The invention provides a method for producing low-carbon olefin and aromatic hydrocarbon, which comprises the following steps:

(1) introducing a catalyst from the upper part of a first reactor, introducing fresh raw oil from the bottom of the first reactor, and carrying out a cracking reaction by countercurrent contact of the catalyst and the fresh raw oil in the first reactor to obtain a first reaction oil gas and a first post-reaction catalyst;

(2) introducing the recycle material flow from the bottom of the second reactor to contact with the first reacted catalyst for cracking reaction to obtain second reacted oil gas and a second reacted catalyst;

(3) and (3) stripping and regenerating the catalyst after the second reaction, and introducing the obtained regenerated catalyst into the first reactor for recycling.

In the present invention, the "aromatic hydrocarbon" is preferably a hydrocarbon having a carbon number of not more than 8 and containing a benzene ring structure, and specifically may be at least one of benzene, toluene, o-xylene, m-xylene, and p-xylene.

According to the present invention, preferably, the first reactor is a dilute phase transport bed reactor; further preferably, the average void fraction of solids during dilute phase transport in the first reactor is 0.8 or more, and still more preferably 0.8 to 0.9.

According to a preferred embodiment of the invention, the first reactor is a riser reactor.

According to the present invention, preferably the second reactor is a dense phase fluidized bed reactor, further preferably the average void volume of solids in the second reactor is below 0.6, further preferably between 0.4 and 0.6.

According to the method provided by the present invention, the first reactor and the second reactor are not particularly limited in structure, and the first reactor and the second reactor may be of the same diameter, variable diameter, straight pipe or curved pipe. Preferably, the first reactor and the second reactor are each independently straight tubes of equal or varying diameter, or are each independently curved tubes of equal or varying diameter. Further preferably, the first reactor and the second reactor are straight pipes of equal diameter.

The present invention is not particularly limited with respect to the inner diameter and height of the first and second reactors, and those skilled in the art can appropriately select them according to the material throughput and material residence time, and preferably, the ratio of the height to the diameter of the first reactor is 40 to 200: 1, the height-diameter ratio of the second reactor is 5-30: 1.

according to a preferred embodiment of the invention, the catalyst contains an active component and an inert component. The preferred embodiment is more beneficial to the counter-current contact reaction in the first reactor, and can ensure the exertion of the catalyst activity.

Preferably, the catalyst is spherical and the active component is wrapped outside the inert component. The spherical shape of the present invention also includes a spheroidal shape without specific reference.

More preferably, the catalyst has an average particle size of 70 μm to 2mm, more preferably 100 μm to 1 mm. The average particle diameter referred to herein refers to the linear average diameter of the catalyst.

According to a preferred embodiment of the present invention, the mass ratio of the inert component to the active component is 1 to 10: 1, preferably 3 to 7: 1.

the active ingredients are selected from a wide range of materials, preferably comprising zeolites, inorganic oxides and optionally clays. By "optional" is meant that the active ingredient may or may not contain clay.

Preferably, the content of the zeolite is 1-60 wt%, the content of the inorganic oxide is 5-99 wt%, and the content of the clay is 0-70 wt% based on the total amount of the active components; further preferably, the content of the zeolite is 30 to 60 wt%, the content of the inorganic oxide is 10 to 50 wt%, and the content of the clay is 10 to 40 wt%.

The zeolite may be at least one selected from the group consisting of rare earth-containing or non-rare earth-containing Y or HY type zeolite, rare earth-containing or non-rare earth-containing ultrastable Y type zeolite, ZSM-5 series zeolite, high-silica zeolite having a pentasil structure, and beta zeolite. The inorganic oxide is used asIs a binder, preferably selected from silicon dioxide (SiO)₂) And/or aluminum oxide (Al)₂O₃). The clay may be various clays conventionally used in the art, such as kaolin and/or halloysite.

According to a preferred embodiment of the invention, the inert component is selected from the group consisting of iron, copper, cobalt, nickel and SiO₂At least one of (1).

The catalyst with the structure and the composition can further improve the selectivity of the low-carbon olefin and the aromatic hydrocarbon and further reduce the yield of dry gas and coke. The method for preparing the catalyst is not particularly limited, and the present invention provides an exemplary illustration of a specific method of the above catalyst, and is not intended to limit the present invention.

The catalyst can be prepared by the following method, the preparation method of the micron-sized inert component belongs to the technical field of powder metallurgy, and preferably, the method comprises the following steps: the micron-sized inert component (for example, 70-2 mm) is placed in a rotating disc inclined at 30-60 degrees, active component powder and a mist-shaped binder (preferably water) are sprayed, the inert component gradually grows into larger round balls along with the continuous rotation of the rotating disc, the friction coefficient of the larger round balls is small, the inert component floats on the surface and rolls out from the lower edge of the rotating disc when the particle size requirement is met, and therefore the required catalyst is prepared.

The method for obtaining the micron-sized inert component is not particularly limited, and may be any suitable conventional technique, for example, by heating inert component powder to form molten droplets, rapidly cooling, solidifying to form spherical inert powder (which may be carried out in a conveying reactor), and sieving the micron-sized inert component (which may be carried out in a fluidized bed) as described above.

According to the invention, the average particle size and the active component content of the prepared catalyst can be controlled by adjusting the inclination angle and the rotating speed of the rotating disc. On the basis of the above disclosure, the person skilled in the art knows how to prepare catalysts of fixed size and specific active component content.

According to the invention, preferably, the mass ratio of the recycle stream to the fresh raw oil is 0.1-0.5: 1, preferably 0.15 to 0.3: 1.

according to a preferred embodiment of the present invention, the reaction conditions of the first reactor comprise: the fresh raw oil inlet temperature is 560-650 ℃, more preferably 580-630 ℃, the oil-gas retention time is 0.2-5 seconds, more preferably 0.5-3 seconds, and the weight ratio of the oil to the solvent is 1-50, more preferably 10-30.

According to a preferred embodiment of the present invention, the reaction conditions of the second reactor comprise: the recycle stream inlet temperature is 550 ℃ and 650 ℃, more preferably 580 ℃ and 630 ℃, and the oil gas residence time is 3-20 seconds, more preferably 5-15 seconds.

According to a most preferred embodiment of the present invention, a method for producing lower olefins and aromatics comprises:

(1) introducing a catalyst from the upper part of a first reactor, introducing fresh raw oil from the bottom of the first reactor, and carrying out a cracking reaction by countercurrent contact of the catalyst and the fresh raw oil in the first reactor to obtain a first reaction oil gas and a first post-reaction catalyst, wherein the reaction conditions of the first reactor comprise: the fresh raw oil inlet temperature is 560-650 ℃, preferably 580-630 ℃, the oil gas residence time is 0.2-5 seconds, preferably 0.5-3 seconds, and the weight ratio of the oil to the solvent is 1-50, preferably 10-30;

(2) introducing the recycle material flow from the bottom of the second reactor to contact with the first reacted catalyst for cracking reaction to obtain a second reacted oil gas and a second reacted catalyst, wherein the reaction conditions of the second reactor comprise: the inlet temperature of the recycle stream is 550-650 ℃, preferably 580-630 ℃, and the oil gas residence time is 3-20 seconds, preferably 5-15 seconds;

(3) stripping and regenerating the catalyst after the second reaction, and introducing the obtained regenerated catalyst into the first reactor for recycling;

wherein the catalyst contains an active component and an inert component; the catalyst is spherical, and the active component is wrapped outside the inert component.

The inventor of the invention discovers in the research process that the selectivity of low-carbon olefin and aromatic hydrocarbon can be further improved by uniquely designing the catalyst and adopting a reactor form that the catalyst is in countercurrent contact with oil and gas from bottom to top along with the gravity in a first reactor, wherein the first reactor adopts a high-temperature, short-retention time and high-activity catalyst to process fresh raw oil, and the second reactor adopts a dense-phase fluidized bed reactor to process difficult-cracking remixed material at proper temperature and reaction time. By adopting the preferred embodiment, the selectivity of the low-carbon olefin and the aromatic hydrocarbon can be further improved, and the yield of dry gas and coke can be obviously reduced.

According to the invention, the fresh raw oil is preferably petroleum hydrocarbon and/or mineral oil; wherein the petroleum hydrocarbon is selected from at least one of vacuum gas oil, atmospheric gas oil, coker gas oil, deasphalted oil, vacuum residue, atmospheric residue, and hydrogenated heavy oil; wherein the mineral oil is selected from at least one of coal liquefaction oil, oil sand oil, shale oil, synthetic oil, and partial fraction or whole fraction of animal and vegetable oil and fat. In the present invention, the fresh feedstock refers to the feedstock which is reacted for the first time in the process of the present invention.

According to the present invention, preferably, the recycle stream is a fraction of the cracked product that can be further cracked into lower olefins and light aromatics. Further preferably, the recycle stream is selected from naphtha fractions and/or diesel light fractions in the second reaction oil gas. The recycle stream may be a portion or all of the naphtha fraction and/or the diesel light fraction.

According to a preferred embodiment of the invention, the recycle stream is selected from the naphtha fraction with a distillation range of 40-205 ℃ in the second reaction oil gas and/or the diesel oil light fraction with a distillation range of 205-335 ℃ in the second reaction oil gas.

According to the invention, in particular, the method further comprises: and carrying out gas-solid separation on the first reaction oil gas and/or the second reaction oil gas, and sending the separated oil gas to a subsequent separation system. Preferably, the first reaction oil gas and the second reaction oil gas are mixed for gas-solid separation, and the separated oil gas is sent to a subsequent separation system.

According to the invention, specifically, the catalyst obtained by gas-solid separation is mixed with the catalyst after the second reaction, and the steam stripping and the regeneration in the step (3) are carried out together.

The stripping and regeneration method in step (3) is not particularly limited, and the stripping and regeneration method is well known to those skilled in the art and will not be described herein.

According to the invention, step (2) comprises in particular: after the catalyst after the first reaction is pre-lifted, the catalyst is introduced from the bottom of the second reactor to contact with the recycle stream for cracking reaction. The pre-lifting may be performed using a pre-lifter.

According to the method provided by the invention, preferably, the method further comprises introducing the regenerated catalyst obtained in the step (3) into the second reactor for recycling. In this preferred embodiment, the regenerated catalyst obtained in step (3) and the catalyst after the first reaction are introduced together into the second reactor and used as a catalyst.

Further preferably, in the second reactor, the mass ratio of the introduced amount of the regenerated catalyst to the introduced amount of the catalyst after the first reaction is from 0.1 to 0.5: 1, more preferably 0.1 to 0.2: 1.

the method provided by the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited thereto.

As shown in fig. 1, the regenerated catalyst enters the regenerated catalyst distributor 4 of the first reactor 1 through the first regenerated catalyst inclined tube 33, the catalyst flows from top to bottom under the action of gravity, the fresh raw oil is injected from the bottom of the first reactor 1 through the fresh raw oil inlet 11, and contacts and cracks with the catalyst along the first reactor 1 in a countercurrent and upward manner, and the cracked product flows out from the first reaction oil gas outlet 12. The catalyst after the first reaction at the outlet of the first reactor 1 enters the pre-lifting device 6 through the catalyst conveying pipe 13, the pre-lifting medium fed through the pre-lifting medium inlet 21 is lifted and then enters the second reactor 2, the recycle material flow is injected from the bottom of the second reactor 2 through the recycle material inlet 22 and contacts with the catalyst to generate a cracking reaction, the regenerated catalyst can also be directly fed into the second reactor 2 through the second regenerated catalyst inclined pipe 34, and the cracked product of the second reactor 2 flows out from the second reaction oil gas outlet 23. The catalyst reacted in the second reactor 2 is stripped by a gas medium in a stripper 5 and then enters a regenerator 3 through a spent catalyst inclined tube 24 for coke burning regeneration, and the regenerated catalyst returns to the first reactor 1 and the optional second reactor 2 for recycling. And carrying out gas-solid separation on the first reaction oil gas and the second reaction oil gas, feeding the separated catalyst into a regenerator for coke burning regeneration after steam stripping, and introducing the oil gas into a product separation system.

The process according to the invention is further illustrated by the following examples, without the invention being restricted thereby.

The basic properties of the fresh raw oil used in the examples and comparative examples are shown in Table 1. The basic properties of the recycle stream used are shown in Table 2.

TABLE 1

TABLE 2

Example 1

The process is carried out in a medium-sized apparatus for continuous reaction-regeneration operation, as shown in FIG. 1, wherein the first reactor 1 is a riser reactor having an inner diameter (diameter) of 60 mm and a height of 6 m. The second reactor 2 was a fluidized bed reactor having an inner diameter (diameter) of 84 mm at the outlet and a height of 1 m. The medium-sized devices use electrical heating to maintain the temperature of the reaction-regeneration system.

The catalyst used in this example consisted of an active component and an inert component, wherein the inert component was spherical iron having an average particle size of 110 μm, and the active component was a powder consisting of 55 wt% of ZSM-5 zeolite, 20 wt% of kaolin and 25 wt% of alumina. The spherical iron was placed in a 50 ° inclined turntable, and active ingredient powder and atomized water were sprayed in at a turntable speed of 100 rpm. With the continuous rotation of the rotating disc, the active component is wrapped outside the spherical iron, the spherical iron gradually grows into larger spheres, the spheres float on the surface of the rotating disc and roll, and the spheres with the diameter of 140-170 μm roll out from the lower edge of the rotating disc to form the catalyst. The average particle size of the catalyst was 158 μm, and the mass ratio of the inert component to the active component of the catalyst was 3: 1. The catalyst was subjected to hydrothermal aging with saturated steam at 800 ℃ for 14 hours before use.

The regenerated catalyst with the temperature of about 680 ℃ enters a regenerated catalyst distributor 4 of a first reactor 1 through a first regenerated catalyst inclined pipe 33, the catalyst flows from top to bottom under the action of gravity, fresh raw oil is preheated to 260 ℃ and is injected from the bottom of the first reactor 1 through a fresh raw oil inlet 11 under the action of atomized steam, the catalyst and the fresh raw oil are subjected to contact cracking along the first reactor 1 in a countercurrent upward direction, and the reaction conditions in the first reactor are listed in Table 3. The first reaction oil gas flows out from the first reaction oil gas outlet 12. The average void fraction of solids during dilute phase transport in the first reactor was 0.82.

The catalyst reacted in the first reactor 1 enters the pre-lifting device 6 through the catalyst conveying pipe 13, enters the second reactor 2 under the pre-lifting action of the steam fed from the pre-lifting medium inlet 21, part of the regenerated catalyst is directly fed into the second reactor 2 through the second regenerated catalyst inclined pipe 34, and the recycle material flow is injected into the second reactor 2 from the bottom through the recycle material flow inlet 22 and contacts with the catalyst to carry out cracking reaction. The oil gas after the reaction in the second reactor 2 flows out from the second reaction oil gas outlet 23. The average void fraction of solids during dense phase transport in the second reactor was 0.48.

The catalyst reacted in the second reactor 2 is stripped by steam in a stripper 5, enters a regenerator 3 through a spent catalyst inclined pipe 24 and contacts with heated air injected from a regeneration air inlet 31 for regeneration at 700 ℃, regenerated flue gas is discharged from a regenerated flue gas outlet 32, and the regenerated catalyst which is burnt, regenerated and recovered in activity is returned to the first reactor 1 and the second reactor 2 for recycling.

The first reaction oil gas and the second reaction oil gas are subjected to gas-solid separation, and the separated catalyst is also fed into the regenerator 3 after steam stripping; the separated reaction oil gas is further separated into dry gas, liquefied gas, gasoline fraction, diesel oil fraction and heavy oil fraction. The results are shown in Table 3.

Example 2

The procedure of example 1 was followed except that the inert component of the catalyst was spherical iron having an average particle size of 440 μm, the spherical iron was placed in a rotating disk inclined at 50 ℃ and the active component powder and atomized water were sprayed in at a rotating speed of 105rpm to obtain a catalyst having an average particle size of 600 μm, and the mass ratio of the inert component to the active component of the catalyst was 3: 1. Wherein the active component is powder consisting of 55 wt% of ZSM-5 zeolite, 20 wt% of kaolin and 25 wt% of alumina. The results are shown in Table 3.

Example 3

The process of example 1 was followed except that the catalyst in the second reactor 2 was entirely from the catalyst after the reaction in the first reactor 1. The results are shown in Table 3.

Example 4

The procedure of example 1 was followed except that the inert component of the catalyst was spherical copper having an average particle diameter of 170 μm, the spherical copper was placed in a rotating disk inclined at 50 ℃ and active component powder and atomized water were sprayed in at a rotating speed of 95rpm to obtain a catalyst having an average particle diameter of 200 μm, and the mass ratio of the inert component to the active component of the catalyst was 7: 1. Wherein the active component is powder consisting of 60 wt% of ZSM-5 zeolite, 25 wt% of kaolin and 15 wt% of alumina. The results are shown in Table 3.

Comparative example 1

The process of example 1 was followed, except that the first reactor 1 was fed with the regenerated catalyst from the bottom up together with fresh feed oil, the catalyst used did not include inert components, and the average particle diameter was 78 μm. The results are shown in Table 3.

Comparative example 2

The process of example 1 was followed except that the first reactor 1 and the second reactor 2 both used regenerated catalyst, i.e., the catalyst reacted in the first reactor 1 was directly fed to the regenerator for regeneration. The results are shown in Table 3.

TABLE 3

As can be seen from the data in Table 3, the method for producing low-carbon olefins and aromatics by catalytic cracking provided by the invention can significantly improve the yield of propylene and obviously reduce the yield of dry gas and coke.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.