A system for producing low-carbon olefins from methanol and a method for preparing the same

Abstract

The application provides a system for producing low-carbon olefins from methanol and a preparation method thereof, and belongs to the technical field of petroleum chemical industry, and solves the problems of small processing capacity, small operation flexibility and high energy consumption of the existing fluidized dense bed layer methanol low-carbon olefin device. It comprises a riser reactor, the riser reactor is connected with a reaction settler, the reaction settler is communicated with a regenerator, the bottom of the regenerator is connected with a regeneration inclined pipe communicated with the riser reactor, the reaction settler is communicated with a first external heat exchanger, and the first external heat exchanger is communicated with the riser reactor. The mixed gas generated by the reaction enters the reaction settler for separation of products and catalysts, the regenerator performs decoking treatment on the catalyst, and finally the catalyst is introduced into the riser reactor again to continue the reaction; the first external heat exchanger is arranged to introduce part of the cooled catalyst into the riser reactor to reduce the temperature, and the reaction time and the requirement of reaction depth can be flexibly adjusted according to the change of the methanol processing capacity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of petrochemical industry, and particularly relates to a system for producing low-carbon olefins from methanol and a preparation method thereof. BACKGROUND

[0002] Ethylene, propylene and butene are important basic chemicals in the field of petrochemical industry and are widely used in the fields of plastics, fibers, medicines and textiles. Ethylene, propylene and butene can be produced by catalytic cracking, naphtha steam cracking, dehydrogenation of ethane, propane and butane, and methanol-to-ethylene, methanol-to-propylene and methanol-to-butene. Among them, the method of producing low-carbon olefins such as ethylene, propylene and butene from methanol is attracting more and more attention due to its wide range of raw materials, low investment and close combination of coal chemical industry and petroleum chemical industry. The reaction of methanol-to-low-carbon alkane is a strong exothermic reaction with short reaction time. Once the "carbon pool" is formed in the methanol-to-low-carbon olefin reaction, the reaction of methanol conversion to low-carbon olefins can be completed in less than 0.2S, and a large amount of heat is released. Ethylene, propylene and butene produced by methanol conversion are very active, and can further generate saturated hydrocarbons, C6+ olefins and coke through cyclization, dehydrogenation, hydrogen transfer, condensation and alkylation under the acid catalysis of molecular sieves. Controlling the reaction time and timely heat removal are the keys to producing low-carbon olefins from methanol. In the already industrialized production device, the main method is to use a dense-phase fluidized bed reactor and a special catalyst based on small-pore SAPO molecular sieves.

[0003] The existing industrialized methanol-to-low-carbon olefin is based on the reaction form of a fluidized catalytic device, and a special catalyst based on small-pore SAPO molecular sieves and a dense-phase fluidized bed reactor are used according to the specific characteristics of methanol-to-low-carbon olefin. This kind of dense-phase fluidized bed reactor needs to maintain a good catalyst dense-phase bed height and a certain reaction time, and lacks good operation flexibility, so the device processing capacity is low.

[0004] The existing special catalyst based on small-pore SAPO molecular sieves has high activity, so that the circulating amount of catalyst between the dense-phase fluidized bed reactor and the regenerator is small, and the respective characteristics of the reactor and the regenerator cannot be exerted through a large amount of catalyst circulation.

[0005] Patent No. CN114133309A discloses a two-stage fluidized bed reactor, in which the upper stage is an MTO reaction stage and the lower stage is a C4C5 reaction stage. Both reactors are fluidized bed reactors, which limit the change of processing scale of the dense-phase bed reactor, and the heat removal equipment is arranged in the dense-phase bed, which is complicated in operation and limits the flexibility of the device.

[0006] Patent No. CN114377729A discloses a fluidized bed regenerator, a device for preparing low-carbon olefins and its application. The fluidized bed regenerator comprises a second activation zone, a first activation zone and a gas-solid separation zone from bottom to top. The invention is also a dense-phase fluidized bed reactor, and the equipment involved in the invention is complex, and the engineering difficulty is large. The obvious shortcomings are that the device processing scale is limited, the operation difficulty is large, and the energy consumption is high.

[0007] Patent No. CN112546974A discloses a fluidized bed reactor for methanol to olefins. It comprises a fast bed reactor, a double dense bed and a cross-type feed distributor, which comprises one or more horizontal feed distribution branches, one or more inclined feed distribution branches and a feed main pipe, wherein the horizontal feed distribution branch and the inclined feed distribution branch are connected with the feed main pipe, and the connection port of the feed main pipe with the fast bed reactor is arranged at the lower part of the fast bed reactor. When the fluidized bed reactor of the invention is used for methanol to olefins, it has the advantage of high oxide conversion rate during oxide recycling. The invention mainly solves the difficulty of improving the conversion rate of oxide during recycling, and has great improvement compared with the previous fluidized bed bed layer reaction, but for methanol raw material, it still has small operation flexibility and cannot adjust the change of reaction heat in time. SUMMARY

[0008] In view of the problems of small processing capacity, small operation flexibility and high energy consumption of the existing fluidized dense-phase bed layer methanol to low-carbon olefins device, the purpose of the present invention is to provide a system for producing low-carbon olefins from methanol and a preparation method thereof. Methanol reacts with catalyst in the riser reactor, the mixed gas generated enters the reaction settler for separation of products and catalyst, the regenerated catalyst is subjected to decoking treatment in the regenerator to restore the activity of the catalyst, and finally the regenerated catalyst is introduced into the riser reactor to continue the reaction. A first external heat exchanger is arranged to recover the heat in the reaction settler, and a part of the cooled catalyst is introduced into the riser reactor to reduce the temperature in the riser reactor. The reaction time and reaction depth requirements can be flexibly adjusted according to the change of methanol processing capacity.

[0009] The technical scheme adopted by the present invention is as follows:

[0010] A system for producing low-carbon olefins from methanol, comprising a riser reactor, wherein the gas outlet end of the riser reactor is connected with a reaction settler, the reaction settler is communicated with a regenerator, the bottom of the regenerator is connected with a regeneration inclined pipe, the regenerator is communicated with the riser reactor through the regeneration inclined pipe, the reaction settler is communicated with a first external heat exchanger, the first external heat exchanger is connected with a downpipe, and the downpipe is communicated with the riser reactor.

[0011] Preferably, the connection between the downpipe and the riser reactor is located above the connection between the regeneration inclined pipe and the riser reactor.

[0012] Preferably, the first external heat exchanger is connected with a return pipe, which is communicated with the reaction settler.

[0013] Preferably, the riser reactor comprises a vertical pipe and a horizontal pipe connected to the upper end of the vertical pipe, the bottom of the vertical pipe is provided with a first lifting medium inlet, and the vertical pipe is provided with a feeding port above the first lifting medium inlet.

[0014] Preferably, the reaction settler comprises a reaction settler shell, a coarse cyclone and a single-stage cyclone are arranged in the reaction settler shell, the gas inlet end of the coarse cyclone is connected with the gas outlet end of the riser reactor, and the inner lower end of the reaction settler shell is provided with a first stripping section.

[0015] Preferably, the regenerator comprises a regenerator shell and a guide pipe penetrating through the bottom of the regenerator shell, the bottom of the guide pipe is provided with a second lifting medium inlet, the guide pipe is communicated with a spent catalyst inclined pipe, the spent catalyst inclined pipe is communicated with the first stripping section, and the inner lower end of the regenerator shell is provided with a second stripping section.

[0016] Preferably, the upper end of the guide pipe is connected with a spent catalyst distributor, and the regenerator shell is connected with a main air distributor below the spent catalyst distributor.

[0017] Preferably, the regenerator shell is provided with a cyclone group.

[0018] A preparation method of producing low-carbon olefins from methanol, comprising the following steps:

[0019] S1, inputting methanol and catalyst into the riser reactor, and conveying the reaction gas generated by the reaction to the reaction settler by the lifting medium;

[0020] S2, the reaction gas enters the coarse cyclone and the single-stage cyclone in sequence, and the spent catalyst is separated and obtained, part of the spent catalyst enters the regenerator after stripping, and the other part of the spent catalyst enters the first external heat exchanger for cooling, and then enters the riser reactor through the discharge pipe;

[0021] S3, the spent catalyst in the regenerator is burned to obtain regenerated catalyst, and the regenerated catalyst flows into the riser reactor from the regenerated inclined pipe after stripping.

[0022] The temperature in the riser reactor is 350-550℃, the pressure is 0.1-0.5MPa, and the reaction time is 0.5-5s; the temperature in the regenerator is 550-700℃.

[0023] In summary, by using the technical scheme, the application has the following advantages:

[0024] Methanol is reacted with catalyst in the riser reactor, the mixed gas generated is introduced into the reaction settler for separation of products and catalyst, the separated catalyst is subjected to decoking treatment in the regenerator to restore the activity of the catalyst, and finally the regenerated catalyst is introduced into the riser reactor to continue the reaction, the first external heat exchanger is arranged to recover the heat in the reaction settler, and a part of the cooled catalyst is introduced into the riser reactor to reduce the temperature in the riser reactor, the requirements of reaction time and reaction depth can be flexibly adjusted according to the change of methanol treatment capacity, the operation flexibility is increased, and the methanol treatment capacity can be increased. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical scheme of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0026] Figure 1 The flowchart is provided for the first embodiment of the application;

[0027] Figure 2 The flowchart is provided for the second embodiment of the application;

[0028] Figure 3 The flowchart is provided for the third embodiment of the application;

[0029] Figure 4 The flowchart is provided for the fourth embodiment of the application.

[0030] BRIEF DESCRIPTION OF DRAWINGS: 1-riser reactor; 2-regeneration flue gas outlet; 3-horizontal pipe; 4-coarse cyclone separator; 5-reaction settler; 6-cyclone separator group; 7-reaction oil gas collecting chamber; 8-first feeding pipe; 9-return pipe; 10-first external heat exchanger; 11-first fluidization air inlet; 12-discharge pipe; 13-first stripping section; 14-green catalyst inclined pipe; 15-feeding port; 16-first lifting medium inlet; 17-regenerated catalyst inclined pipe; 18-third slide valve; 19-second lifting medium inlet; 20-second slide valve; 21-main air distributor; 22-second stripping section; 23-second fluidization air inlet; 24-second feeding pipe; 25-second external heat exchanger; 26-green catalyst distributor; 27-regenerator; 28-first slide valve; 29-introduction pipe; 30-single-stage cyclone separator; 31-collection partition. DETAILED DESCRIPTION

[0031] So that the purposes, technical solutions and advantages of the embodiments of the present application are more apparent, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0033] In the description of the present application, it should be noted that if the terms “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, “outer” and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship of the product of the application when it is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0034] The present application will be described in detail below. Figures 1-4 The present application will be described in detail below.

[0035] Embodiment

[0036] Embodiment 1:

[0037] A system for producing low-carbon olefins from methanol comprises a riser reactor 1, a reaction settler 5 connected to the gas outlet end of the riser reactor 1, a regenerator 27 communicated with the reaction settler 5, a regenerative inclined pipe 17 connected to the bottom of the regenerator 27, the regenerator 27 communicated with the riser reactor 1 through the regenerative inclined pipe 17, a first external heat exchanger 10 communicated with the reaction settler 5, a downcomer 12 connected to the first external heat exchanger 10, and the downcomer 12 communicated with the riser reactor 1.

[0038] As shown, the spent catalyst (the carbon content on the spent catalyst is 1-7%) is introduced into the riser reactor 1 through the downcomer 12 and the regenerative inclined pipe 17, which ensures the concentration of the catalyst in the riser reactor 1, provides the required temperature for producing low-carbon olefins from methanol, and maintains a large catalyst circulation amount to maintain the reaction heat capacity of the catalyst in the riser reactor 1, so that the temperature of the riser reactor 1 is controllable and adjustable, and can be flexibly adjusted according to the change of the methanol treatment amount. Figure 1 ​

[0039] The outlet of the downcomer 12 can be arranged above or below the outlet of the regenerative inclined pipe 17, and in order to better react the methanol and reduce energy loss, the connection between the downcomer 12 and the riser reactor 1 is arranged above the connection between the regenerative inclined pipe 17 and the riser reactor 1, so that the high-temperature catalyst is first contacted with the methanol to heat the methanol to about 350°C, reaching the initial reaction temperature of the methanol, and then contacted with the low-temperature catalyst containing carbon pool to make the methanol react rapidly.

[0040] The first external heat exchanger 10 is connected with the first feeding pipe 8 which is communicated with the reaction settler 5, and the first feeding pipe 8 is arranged obliquely to the first external heat exchanger 10 to facilitate the flow of catalyst into the first external heat exchanger 10. The first external heat exchanger 10 is also connected with a heat extraction pipe which evaporates water in the pipe to extract heat after absorbing heat. The bottom of the first external heat exchanger 10 is also provided with a first fluidization air inlet 11 which introduces gas to keep the catalyst in the first external heat exchanger 10 and the reaction settler 5 in a flowing state, ensuring that the pipeline will not be blocked. The return pipe 9 which is communicated with the reaction settler 5 can introduce excess fluidization air into the first external heat exchanger 10 again for reuse, increasing the utilization rate of fluidization air.

[0041] The riser reactor 1 includes a vertical pipe and a horizontal pipe 3 connected to the upper end of the vertical pipe, and the bottom of the vertical pipe is provided with a first lifting medium inlet 16, and the vertical pipe is provided with a feeding port 15 above the first lifting medium inlet 16. Methanol is introduced into the vertical pipe through the feeding port 15, and the first lifting medium inlet 16 inputs lifting gas to mix and react the methanol and catalyst, and the reaction gas enters the reaction settler 5 through the horizontal pipe 3.

[0042] The reaction settler 5 comprises a reaction settler shell, a rough cyclone 4 and a single-stage cyclone 30 are arranged in the reaction settler shell, the gas inlet end of the rough cyclone 4 is connected with the gas outlet end of the riser reactor 1, and the inner lower end of the reaction settler shell is provided with a first stripping section 13. The rough cyclone 4 separates the catalyst from the reaction gas generated by the riser reactor 1; in the rough cyclone 4, the reaction gas and the catalyst are separated in a very short time, greatly reducing the side reactions (cracking, condensation, coking and other reactions of the reaction gas rich in olefins), and ensuring the selectivity of the methanol-to-olefin process. The separated catalyst falls into the first stripping section 13, steam is introduced into the first stripping section 13 to replace the reaction gas entrained in the catalyst, preventing the reaction gas of methanol from being entrained into the regenerator 27 or the riser reactor 1, causing waste of raw materials and increasing the cracking of olefins in the reaction product. The rough cyclone 4 and the single-stage cyclone 30 are not connected, which facilitates the entry of other gases in the reaction settler 5 into the single-stage cyclone 30; the gas first enters the rough cyclone 4 for separation of large-particle catalyst, and the gas discharged from the rough cyclone 4 enters the single-stage cyclone 30 again for separation; the gas outlet of the single-stage cyclone 30 is connected with a reaction oil gas collecting chamber 7, and the reaction oil gas collecting chamber 7 collects the reaction gas. The efficiencies of the rough cyclone 4 and the single-stage cyclone 30 are both above 90%, and the rough cyclone 4 and the single-stage cyclone 30 are provided with 6 groups or 8 groups, and the total separation efficiency is above 99.99%.

[0043] The regenerator 27 comprises a regenerator shell and a lead-in pipe 29 penetrating through the bottom of the regenerator shell, the bottom of the lead-in pipe 29 is provided with a second lifting medium inlet 19, the lead-in pipe 29 is communicated with a spent catalyst inclined pipe 14, the spent catalyst inclined pipe 14 is communicated with the first stripping section 13, and the inner lower end of the regenerator shell is provided with a second stripping section 22. The spent catalyst flows into the lower end of the lead-in pipe 29 through the spent catalyst inclined pipe 14, the spent catalyst is transported into the regenerator 27 by inputting lifting gas through the second lifting medium inlet 19 to perform a coking operation to obtain regenerated catalyst (the carbon content on the regenerated catalyst is 0.1-1%); since the spent catalyst is transported by using lifting gas, the spent catalyst can be dispersed into the regenerator 27, ensuring the coking effect; the second stripping section 22 replaces the air in the coked catalyst, preventing the air from being entrained into the regenerated inclined pipe 17. The first stripping section 13 and the second stripping section 22 are provided with annular and disc-shaped gratings, the gratings can break bubbles, increase the gas-solid contact probability, and improve the stripping effect.

[0044] A first slide valve 28 is installed in the feed pipe 12 to prevent gas in the riser reactor 1 from entering the first external heat exchanger 10; a second slide valve 20 is installed in the regeneration inclined pipe 17 to prevent gas in the riser reactor 1 from entering the regenerator 27; a third slide valve 18 is installed in the waiting inclined pipe 14 to prevent gas in the regenerator 27 from entering the reaction settling tank 5.

[0045] To further enhance the coking effect of the catalyst, it is necessary to increase the contact area between the catalyst and air. Therefore, a catalyst distributor 26 is connected to the upper end of the inlet pipe 29, and a main air distributor 21 located below the catalyst distributor 26 is connected to the regenerator shell. The distributor evenly disperses the catalyst and air, ensuring uniform mixing and thus improving the coking efficiency. The outlets of the catalyst distributor 26 and the main air distributor 21 are positioned opposite each other, allowing the catalyst and air to mix counter-currently during coking, ensuring both coking time and coking effect.

[0046] A cyclone separator assembly 6 is installed inside the regenerator housing. The cyclone separator assembly 6 further separates the catalyst from the gas, reducing catalyst loss. The outlet of the cyclone separator assembly 6 is connected to the regeneration flue gas outlet 2, from which excess gas is discharged and then discharged to the waste heat recovery unit.

[0047] Setting up cyclone separator group 6 as a two-stage cyclone separator can ensure the separation effect of the catalyst; the gas enters from the inlet of the first-stage cyclone separator, undergoes preliminary separation, and then enters the second-stage cyclone separator through the pipeline for further separation.

[0048] The regenerator 27 is connected to the second external heat exchanger 25, which recovers and reuses the heat in the regenerator 27. The second external heat exchanger 25 is connected to a second feed pipe 24, which communicates with the regenerator 27. The second external heat exchanger 25 is also connected to a heat exchange tube, which absorbs heat and causes the water in the tube to evaporate, thereby extracting heat. The bottom of the second external heat exchanger 25 is also provided with a second fluidizing air inlet 23, which introduces gas to keep the catalyst in the second external heat exchanger 25 and the regenerator 27 in a flowing state, ensuring that the pipeline is not blocked.

[0049] Example 2:

[0050] The second arrangement of the riser reactor 1, the reaction settling tank 5, and the regenerator 27 in this application is as follows: Figure 2 As shown. Figure 2 The diagram shows a coaxial arrangement of the riser reactor 1 and the reaction settling tank 5. The riser reactor 1 extends from the bottom of the reaction settling tank 5 and into it, and is connected to the coarse cyclone separator 4. In this configuration, the riser reactor 1 is an externally folded riser.

[0051] After the reaction gas is separated by the coarse cyclone separator 4 and the single-stage cyclone separator 30, the catalyst to be generated is obtained. After being stripped by the first stripping section 13, the catalyst enters the regenerator 27 through the catalyst inclined tube 14. Since the outlet of the catalyst inclined tube 14 is located above the main air distributor 21, the catalyst to be generated can flow directly to the main air distributor 21 and mix with air for coking.

[0052] This layout structure has the advantages of simple operation, strong resistance to accidents, and small footprint.

[0053] Example 3:

[0054] The third arrangement of the riser reactor 1, the reaction settling tank 5, and the regenerator 27 in this application is as follows: Figure 3 As shown. Compared to the second arrangement, the difference in the third arrangement is the increase in the dilute phase section and dense phase section of the regenerator 27, so that the regenerator 27 and the reaction settling tank 5 are at the same height. The second or third arrangement can be adopted according to the pressure balance.

[0055] Example 4:

[0056] The fourth arrangement of the riser reactor 1, the reaction settling tank 5, and the regenerator 27 in this application is as follows: Figure 4 As shown. The fourth arrangement structure, like the first arrangement structure, uses an external riser reactor 1. The fourth arrangement structure combines the reaction settling tank 5 and the regenerator 27, which can also reduce the footprint of the equipment.

[0057] In this arrangement, the regenerator 27 is located below the reaction settling tank 5. The pre-regenerated inclined tube 14 is replaced by a vertical tube directly connected to the first stripping section 13 and the inlet pipe 29. After being stripped by the first stripping section 13, the pre-regenerated catalyst falls into the inlet pipe 29. The second lifting medium inlet 19 inputs the lifting medium to transport the pre-regenerated catalyst to the pre-regenerated catalyst distributor 26, and sprays it evenly from the pre-regenerated catalyst distributor 26 to ensure that the pre-regenerated catalyst is fully combusted. After the pre-regenerated catalyst is charred, the regenerated catalyst is obtained. After being stripped by the second stripping section 22, the regenerated catalyst flows into the riser reactor 1 from the regeneration inclined tube 17.

[0058] The reaction settling device 5 is equipped with a collection baffle 31, which forms a collection trough structure with the outer shell of the reaction settling device, so that the catalyst separated by the coarse cyclone separator 4 can enter the first feed pipe 8.

[0059] A method for producing low-carbon olefins from methanol includes the following steps:

[0060] S1, inputting methanol and catalyst into the riser reactor 1, and transporting the reaction gas generated by the reaction to the reaction settler 5 by the lifting medium;

[0061] S2, the reaction gas enters the rough cyclone separator 4 and the single-stage cyclone separator 30 in sequence, and the spent catalyst is separated, wherein a part of the spent catalyst enters the regenerator 27 after stripping, and the other part of the spent catalyst enters the first external heat exchanger 10 for cooling, the temperature of the spent catalyst is reduced by 50-150℃, and the spent catalyst enters the riser reactor 1 through the downcomer 12, and the part of the spent catalyst accounts for 30-80w% of the amount of catalyst in the riser reactor 1;

[0062] S3, the spent catalyst in the regenerator 27 is burned to obtain regenerated catalyst, and the regenerated catalyst flows into the riser reactor 1 from the regeneration inclined pipe 17 after stripping.

[0063] The temperature in the riser reactor 1 is 350-550℃, the pressure is 0.1-0.5MPa, and the reaction time is 0.5-5s; the preferred temperature in the riser reactor 1 is 450-500℃, the pressure is 0.1-0.25MPa, and the reaction time is 1-2s. The temperature in the regenerator 27 is 550-700℃, which can ensure that the waste heat recovery of the rear regeneration flue gas does not need a CO incinerator and the like, reduces the investment, and increases the stability of the device operation; after complete combustion, the performance of the catalyst can be well played, and the efficiency of the catalyst can be increased. The methanol-to-light olefin reaction is carried out under the condition that the catalyst-to-methanol ratio is 0.1-8, the reaction can be quickly completed, and the preferred catalyst-to-methanol ratio is 0.2-6.

[0064] The catalyst used in the application is a methanol-to-light olefin acidic catalyst based on small-pore SAPO molecular sieve, which is used in a riser fluidized bed, the reaction pressure is 0.01-1 MPa, the temperature is 350-550 DEG C, the mass space velocity is 0.3-8 h; the methanol-to-light olefin catalyst comprises the following components by mass fraction based on the total mass of the methanol-to-light olefin catalyst dry basis: 0.1-30% of alumina, 0.1-10% of a first additive, 0.1-60% of a second additive, and the balance is a fluidized bed carrier; the first additive is SAPO molecular sieve with good pore size distribution, so that the catalyst has higher target product selectivity; the second additive is an inert agent, which significantly enhances the strength and stability of the catalyst, the catalyst has a longer service life, and the catalyst circulation amount is increased, the catalyst circulation amount is increased from less than 100 t / h to about 1000 t / h, the operation of a large catalyst to oil ratio similar to a catalytic cracking device is realized; due to the increase of the catalyst circulation amount, the heat capacity of the catalyst in the riser reactor 1 is improved, the operation of a large catalyst to oil ratio similar to a catalytic cracking device can be truly realized, the riser reactor 1 reaction temperature control can be adjusted in time, the processing scale of a single device is greatly increased, and the excellent selectivity and stability of the catalyst are also increased.

[0065] The present riser fluidized bed reactor can rapidly increase the single device methanol processing scale from 2 million tons / year to 5 million tons / year, and this reaction form can greatly reduce investment, reduce energy consumption, and ensure the selectivity of methanol-to-olefin.

[0066] The above is only a preferred embodiment of the present application and is not used to limit the present application, and for those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A system for producing low-carbon olefins from methanol, comprising a riser reactor (1), wherein a reaction settling device (5) is connected to the outlet end of the riser reactor (1), the reaction settling device (5) is connected to a regenerator (27), the bottom of the regenerator (27) is connected to a regeneration inclined tube (17), and the regenerator (27) is connected to the riser reactor (1) through the regeneration inclined tube (17), characterized in that, The reaction settling device (5) is connected to a first external heat exchanger (10), and the first external heat exchanger (10) is connected to a feed pipe (12). The feed pipe (12) is connected to the riser reactor (1). The reaction settling device (5) includes a reaction settling device shell. A coarse cyclone separator (4) and a single-stage cyclone separator (30) are provided inside the reaction settling device shell. The air inlet of the coarse cyclone separator (4) is connected to the air outlet of the riser reactor (1). A first stripping section (13) is provided at the lower end of the interior of the reaction settling device shell. The connection between the feed pipe (12) and the riser reactor (1) is located above the connection between the regeneration inclined pipe (17) and the riser reactor (1), so that the high-temperature catalyst first contacts the methanol, thereby heating the methanol to the initial reaction temperature of methanol, and then contacts the low-temperature catalyst. The low-temperature catalyst contains carbon pools, which makes the methanol react rapidly. The riser reactor (1) includes a riser and a horizontal pipe (3) connected to the upper end of the riser. The bottom of the riser is provided with a first riser medium inlet (16), and the riser is provided with a feed inlet (15) located above the first riser medium inlet (16).

2. The system for producing low-carbon olefins from methanol according to claim 1, characterized in that, The first external heat exchanger (10) is connected to a return pipe (9), which is connected to the reaction settling device (5).

3. The system for producing low-carbon olefins from methanol according to claim 1, characterized in that, The regenerator (27) includes a regenerator housing and an inlet pipe (29) that penetrates the bottom of the regenerator housing. The bottom of the inlet pipe (29) is provided with a second lifting medium inlet (19). The inlet pipe (29) is connected to a pre-generation inclined pipe (14). The pre-generation inclined pipe (14) is connected to a first stripping section (13). The lower end of the interior of the regenerator housing is provided with a second stripping section (22).

4. A system for producing low-carbon olefins from methanol according to claim 3, characterized in that, The upper end of the inlet pipe (29) is connected to the catalyst distributor (26), and the regenerator shell is connected to the main air distributor (21) located below the catalyst distributor (26).

5. A system for producing low-carbon olefins from methanol according to claim 3, characterized in that, The regenerator housing is equipped with a cyclone separator assembly (6).

6. A method for preparing low-carbon olefins from methanol, characterized in that, Using the system according to any one of claims 1-5 includes the following steps: S1. Methanol and catalyst are introduced into the riser reactor (1), and the reaction gas generated by the reaction is transported to the reaction settling tank (5) by the riser medium. S2. The reaction gas enters the coarse cyclone separator (4) and the single-stage cyclone separator (30) in sequence to separate the catalyst to be generated. Part of the catalyst is stripped and then enters the regenerator (27), while the other part of the catalyst is cooled in the first external heat exchanger (10) and enters the riser reactor (1) through the feed pipe (12). S3. The catalyst to be generated in the regenerator (27) is coked to obtain the regenerated catalyst. After stripping, the regenerated catalyst flows from the regenerated inclined tube (17) into the riser reactor (1).

7. The method for preparing low-carbon olefins from methanol according to claim 6, characterized in that, The temperature in the riser reactor (1) is 350-550℃, the pressure is 0.1-0.5MPa, and the reaction time is 0.5-5s; the temperature in the regenerator (27) is 550-700℃.

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