Method for preparing low-carbon olefin

Abstract

The invention relates to a method for preparing low-carbon olefin, which comprises the following steps: contacting an olefin-rich raw material with a thermal regeneration catalyst, and carrying out a first catalytic conversion reaction in a dense-phase fluidized bed layer of a first reactor provided with an instant energy supplement system, the reacted material flow is rapidly cooled through a cooling area, close to the upper part, in the first reactor, so that the reacted material flow is cooled to a target temperature of 450-530 DEG C and then is sent out of the first reactor. According to the method, heat is immediately supplemented for the dense-phase fluidized bed layer, so that the olefin-rich raw material is subjected to catalytic cracking reaction within a proper reaction temperature range, the influence caused by overlarge temperature drop in the reaction process is reduced, and the light raw material is promoted to be subjected to single-molecule cracking reaction; and the yield and the selectivity of low-carbon olefins with high added value, such as ethylene, in the obtained product are improved.

Description

Technical Field

[0001] The invention belongs to the field of petrochemical industry, and in particular, relates to a method for preparing low-carbon olefins. Background Art

[0002] Low-carbon olefins represented by ethylene and propylene are basic raw materials for the chemical industry and can be used to produce synthetic resins, rubber and a variety of fine chemical products. At present, low-carbon olefins are mostly produced by steam cracking process using natural gas or light petroleum fractions as raw materials. However, domestic crude oil is generally heavy, and the yield of light hydrocarbon oil cannot meet the raw material demand. Moreover, after years of development and continuous improvement, steam cracking technology still has limitations such as high energy consumption, high production costs and difficult to adjust product structure.

[0003] In order to meet the needs of the petrochemical industry, the art has currently developed a process for producing low-carbon olefins by cracking high-carbon olefins in refineries. For example, CN114763483A discloses a catalytic conversion method for producing ethylene and propylene from olefin-rich raw materials. This method effectively increases the yield of ethylene and propylene by high-temperature cracking of olefin-rich raw materials and can reduce the methane selectivity in the product. CN101092323A discloses a method for producing ethylene and propylene. This method uses C 4 -C 8 The olefins are used as raw materials for catalytic cracking, and the products after the reaction are separated and the separated C 4 The fraction is returned to the reactor for cracking, and the C 4 The distillation increases the conversion of olefins.

[0004] However, in actual production, there are still problems with low yield and selectivity of light olefins. Summary of the invention

[0005] The purpose of the present invention is to further improve the yield and selectivity of light olefins.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a method for producing low-carbon olefins, which method comprises the following steps: contacting an olefin-rich raw material with a first thermally regenerated catalyst, and carrying out a first catalytic conversion reaction in a dense phase fluidized bed of a first reactor equipped with an instant heat replenishment system, and rapidly cooling the post-reaction logistics in a cooling zone near the top of the first reactor, and sending the post-reaction logistics out of the first reactor after cooling it to a target temperature of 450-530°C.

[0007] Optionally, the instant heat replenishment system includes a catalyst replenishment pipe for introducing additional hot regenerated catalyst into the dense fluidized bed, or the instant heat replenishment system includes a heater arranged in the dense fluidized bed of the first reactor; the heating medium in the heater is at least one of high-temperature steam and steam cracking gas.

[0008] Optionally, the mass ratio of the first thermally regenerated catalyst to the mass ratio of the olefin-rich feedstock is (1-100):1, preferably (10-50):1.

[0009] Optionally, the post-reaction logistics is cooled to the target temperature after the post-reaction logistics is cooled within 0.5-2 seconds, preferably within 0.5-1 second.

[0010] Optionally, the catalyst density of the first thermally regenerated catalyst in the dense phase fluidized bed of the first reactor is 100-700 kg / m 3 , preferably 300-600kg / m 3 , more preferably 400-500kg / m 3 .

[0011] Optionally, the first reactor includes, from bottom to top, a first lifting section, an expansion section, a dense phase fluidization section, a reduction section and a second lifting section; the angle between the side wall of the expansion section and the axis is 5-60 degrees; the ratio of the diameter to the height of the dense phase fluidization section is (0.1-10):1; the angle between the side wall of the reduction section and the axis is 5-60 degrees; the head of the first lifting section is provided with a first heat regeneration catalyst inlet and a lifting medium inlet; the middle of the first lifting section is provided with a raw material inlet; the tail of the first lifting section is also provided with a gas-solid mixed fluid distributor; the cooling zone is provided at the tail of the dense phase fluidization section; preferably, the cooling zone is provided with a plurality of fluid distributors for introducing the coolant, and the fluid distributors are arranged in an annular shape along the circumference of the first reactor; preferably, the cooling medium is a coolant and / or a cooled regenerated catalyst; the coolant is selected from at least one of liquefied gas, crude gasoline, stabilized gasoline, diesel, heavy diesel, water and olefins with eight or more carbon atoms.

[0012] Optionally, the conditions of the first catalytic conversion reaction include: a reaction temperature of 550-750°C, preferably 600-750°C, and more preferably 650-700°C; a reaction pressure of 0.1-1MPa, preferably 0.1-0.7MPa; a reaction time of 0.2-10s, preferably 0.2-0.5s; a weight ratio of the first thermally regenerated catalyst to the olefin-rich feedstock of (1-100):1, preferably (5-50):1; preferably, C in the olefin-rich feedstock is 4 -C8 The olefin content is 50-100wt%, preferably 80-100wt%, and more preferably 90-100wt%; preferably, the olefin-rich raw material is selected from C 4 The above fractions, C produced by the catalytic cracking unit of the refinery 4 The above fractions, C produced by the steam cracking unit of the ethylene plant 4 The above fractions and MTO by-product C 4 The above olefin-rich fractions and the C 4 One or more of the above olefin-rich fractions.

[0013] Optionally, based on the total weight of the first thermally regenerated catalyst, the first thermally regenerated catalyst comprises 1-50 wt% of molecular sieves, 5-99 wt% of inorganic oxides and 0-70 wt% of clay; the silicon-aluminum ratio of the molecular sieve is 10-1000; the molecular sieve is selected from one or more of ZSM-5 series molecular sieves and SAPO series molecular sieves; preferably, it is a medium-pore ZSM-5 series molecular sieve; the inorganic oxide is selected from one or more of silicon dioxide and aluminum oxide; the clay is selected from one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite.

[0014] Optionally, the method further comprises the following steps: subjecting the post-reaction logistics to gas-solid separation to obtain olefin-containing reaction oil gas and a first spent catalyst, and then charring the first spent catalyst and returning it to the first reactor.

[0015] Optionally, the method further comprises the following steps: contacting the heavy hydrocarbon oil with a second thermally regenerated catalyst in a second reactor for a second catalytic conversion reaction to obtain a reaction stream containing light oil; when the temperature of the reaction stream containing light oil in the upper region of the reaction zone of the second catalytic conversion reactor exceeds 530° C., setting a cooling zone downstream of the reaction zone to cool the reaction stream containing light oil to below 530° C.; mixing the cooled reaction stream containing light oil with the reaction stream, and performing catalyst separation on the mixed stream to obtain a mixed reaction stream and a mixed catalyst to be regenerated; performing a first separation on the mixed reaction stream to obtain dry gas, light olefins and C 4 The above distillates, for the C 4The above fraction oil is subjected to a second separation and the separated olefin-rich component is returned to the first reactor for further reaction; and the mixed catalyst to be regenerated by charring and the regenerated catalyst is returned to the first reactor and the second reactor respectively; preferably, the conditions of the first catalytic conversion reaction include: a reaction temperature of 500-650°C, preferably 550-600°C; a reaction pressure of 0.01-1MPa, preferably 0.05-1MPa; a reaction time of 0.01-80s, preferably 0.1-60s; a weight ratio of the second thermally regenerated catalyst to the heavy hydrocarbon oil of (1-100):1, preferably (3-50):1.

[0016] Through the above technical solution, the present invention has the following beneficial effects:

[0017] (1) The present invention provides instant heat supplementation for the dense phase fluidized bed layer, so that the olefin-rich raw material undergoes catalytic cracking reaction within a suitable reaction temperature range, thereby reducing the impact of excessive temperature drop during the reaction, promoting the unimolecular cracking reaction of the light raw material, and improving the yield and selectivity of high value-added low-carbon olefins such as ethylene in the obtained product;

[0018] (2) The present invention optimizes the control of catalytic cracking reaction and thermal cracking reaction by rapidly cooling the post-reaction logistics in the cooling zone through a cooling medium, which can effectively inhibit the deep reaction in the reaction process and improve the yield and selectivity of light olefins.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 A schematic diagram of an embodiment of the first reactor provided by the present invention.

[0022] Figure 2 A schematic diagram of another embodiment of the first reactor provided by the present invention.

[0023] Figure 3 A schematic diagram of an embodiment of the method provided by the present invention.

[0024] Figure 4 A schematic diagram of another embodiment of the method provided by the present invention.

[0025] Description of Reference Numerals

[0026] 1 pipeline 2 first lifting section 3 regeneration inclined pipe

[0027] 4 Feeding pipeline 5 Gas-solid mixed fluid distributor 6 Pipeline

[0028] 7 pipeline 8 feed fluid distributor 9 heater

[0029] 10 Feed pipeline 11 First catalytic conversion reaction zone 12 Pipeline

[0030] 13 fluid distributor 14 cooling zone 15 second lifting section

[0031] 16 horizontal pipe 17 pipeline 18 pre-lift medium

[0032] 19 Feed pipeline 20 Pre-lift section 21 Second catalytic conversion reaction zone

[0033] 22 Stripping steam 23 Stripping section 24 Waiting for production inclined tube

[0034] 25 outlet section 26 settler 27 gas collecting chamber

[0035] 28 pipeline 29 regenerator 30 regeneration inclined tube

[0036] 31 distillation tower 32 pipeline 33 pipeline

[0037] 34 pipeline 35 pipeline 36 pipeline

[0038] 37 pipeline 38 alkane olefin separation unit 39 pipeline

[0039] 40 pipeline 41 pipeline 42 pipeline DETAILED DESCRIPTION

[0040] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0041] The inventors found that when catalytic cracking of olefin-rich raw materials is used to prepare light olefins, small molecules require a higher reaction temperature for activation. As the reaction proceeds, the temperature of the reaction material gradually drops below the optimum reaction temperature. When the temperature drops to a large extent, the olefin raw materials are prone to polymerization, and the cracking of light raw materials gradually tends to bimolecular cracking, which leads to a decrease in the yield of ethylene and the like, while an increase in the yield of butene and olefins with a higher carbon number. Therefore, the present invention is specially proposed.

[0042] The present invention provides a method for preparing low-carbon olefins, which comprises the following steps: contacting an olefin-rich raw material with a first thermally regenerated catalyst, and performing a first catalytic conversion reaction in a dense phase fluidized bed of a first reactor provided with an instant heat replenishment system, and rapidly cooling the post-reaction logistics in a cooling zone near the top of the first reactor, and sending the post-reaction logistics out of the first reactor after cooling the logistics to a target temperature of 450-530°C.

[0043] The present invention can make the olefin-rich raw material undergo catalytic cracking reaction within a suitable reaction temperature range by instantly replenishing heat for the dense phase fluidized bed, thereby reducing the impact of excessive temperature drop during the reaction, promoting the unimolecular cracking reaction of the light raw material, and improving the yield and selectivity of low-carbon olefins with high added value such as ethylene in the obtained product. At the same time, by rapidly cooling the post-reaction logistics in the cooling zone through the cooling medium, the control of the catalytic cracking reaction and the thermal cracking reaction is optimized, the deep reaction during the reaction can be effectively suppressed, and the yield and selectivity of the low-carbon olefins can be improved.

[0044] Wherein, the instant heat supplement system includes a catalyst supplement pipe for introducing additional hot regenerated catalyst into the dense fluidized bed, or the instant heat supplement system includes a heater arranged in the dense fluidized bed of the first reactor; the heating medium in the heater is at least one of high-temperature steam and steam cracking gas. By instantly supplementing heat to the dense fluidized bed, the polymerization reaction of olefin molecules under low temperature conditions can be significantly inhibited, the generation of large molecular olefin products can be reduced, and the selectivity and yield of low-carbon olefins, especially ethylene products, in the product can be improved, thereby obtaining high-quality and high-selectivity target products.

[0045] The mass ratio of the first thermally regenerated catalyst after regeneration to the olefin-rich feedstock is (1-100):1, preferably (10-50):1.

[0046] The post-reaction logistics is cooled to the target temperature within 0.5-2 seconds, preferably within 0.5-1 second.

[0047] The catalyst density of the first thermally regenerated catalyst in the dense phase fluidized bed of the first reactor is 100-700 kg / m 3 , preferably 300-600kg / m 3 , more preferably 400-500kg / m 3 .

[0048] in, Figure 1 A schematic diagram of an embodiment of the first reactor provided by the present invention is as follows Figure 1As shown, the first reactor includes, from bottom to top, a first lifting section, an expansion section, a dense phase fluidization section, a reduction section, and a second lifting section. The angle between the side wall of the expansion section and the axis is 5-60 degrees; the ratio of the diameter to the height of the dense phase fluidization section is (0.1-10): 1; the angle between the side wall of the reduction section and the axis is 5-60 degrees.

[0049] The head of the first lifting section is provided with a first heat regeneration catalyst inlet and a lifting medium inlet, and the middle is provided with a raw material inlet; the tail of the first lifting section is also provided with a gas-solid mixed fluid distributor, which includes a transversely arranged distribution plate with a plurality of openings and a distribution pipe connected to the openings. The side wall of the expansion section is provided with an inlet for introducing a heat regeneration catalyst to instantly supplement heat to the reaction system.

[0050] In the present invention, the cooling zone is arranged at the tail of the dense phase fluidization section;

[0051] Specifically, a heat collector for cooling the post-reaction logistics is provided in the cooling zone. Preferably, the cooling zone is provided with a plurality of fluid distributors for introducing the coolant, and the fluid distributors are arranged in a ring shape along the circumference of the first reactor.

[0052] As a preferred embodiment, the heat collector is arranged along the circumference of the cooling zone, or the heat collector is annular. The medium in the heat collector flows to remove part of the heat of the reactant flow, thereby achieving the purpose of inhibiting thermal cracking, secondary cracking and deep reaction of the reactant.

[0053] Preferably, the cooling medium is a coolant and / or a cooled regenerated catalyst. Specifically, the coolant is selected from at least one of liquefied gas, crude gasoline, stabilized gasoline, diesel, heavy diesel, water and olefins with eight or more carbon atoms.

[0054] Specifically, the second lifting section may be cylindrical, and preferably, a horizontal pipe is connected to the end of the second lifting section to connect to a subsequent catalyst separation device. The diameter or shape of the second lifting section and the horizontal pipe may be determined according to actual needs.

[0055] Among them, the conditions of the first catalytic conversion reaction include: reaction temperature of 550-750°C, preferably 600-750°C, further preferably 650-700°C; reaction pressure of 0.1-1MPa, preferably 0.1-0.7MPa; reaction time of 0.2-10s, preferably 0.2-0.5s; weight ratio of the first thermally regenerated catalyst to the olefin-rich feedstock is (1-100):1, preferably (5-50):1.

[0056] Preferably, the olefin-rich feedstock contains C 4 -C8 The content of olefin is 50-100 wt %, preferably 80-100 wt %, and more preferably 90-100 wt %.

[0057] Preferably, the olefin-rich raw material is selected from C 4 The above fractions, C produced by the catalytic cracking unit of the refinery 4 The above fractions, C produced by the steam cracking unit of the ethylene plant 4 The above fractions, MTO (methanol to olefins) by-product C 4 The above olefin-rich fractions and the C 4 One or more of the above olefin-rich fractions.

[0058] In a preferred embodiment of the present invention, the alkane dehydrogenation to produce the olefin-rich raw material can come from at least one of naphtha, aromatic raffinate or other light hydrocarbons; in actual production, alkane products produced by other different petrochemical plants can also be used.

[0059] Wherein, based on the total weight of the first thermally regenerated catalyst, the first thermally regenerated catalyst comprises 1-50 wt% of molecular sieve, 5-99 wt% of inorganic oxide and 0-70 wt% of clay; the silicon-aluminum ratio of the molecular sieve is 10-1000.

[0060] Preferably, the molecular sieve is selected from one or more of the ZSM-5 series molecular sieves and the SAPO series molecular sieves; preferably, it is the medium-pore ZSM-5 series molecular sieves; the inorganic oxide is selected from one or more of silicon dioxide and aluminum oxide; the clay is selected from one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite.

[0061] The method further comprises the following steps: subjecting the post-reaction logistics to gas-solid separation to obtain reaction oil gas containing olefins and a first spent catalyst, and then charring the first spent catalyst and returning it to the first reactor.

[0062] The method further comprises the following steps: contacting the heavy hydrocarbon oil with the second thermally regenerated catalyst in the second reactor for a second catalytic conversion reaction to obtain a reaction stream containing light oil; when the temperature of the reaction stream containing light oil in the upper region of the reaction zone of the second catalytic conversion reactor exceeds 530° C., setting a cooling zone downstream of the reaction zone to cool the reaction stream containing light oil to below 530° C.; mixing the cooled reaction stream containing light oil with the reaction stream, and performing catalyst separation on the mixed stream to obtain a mixed reaction stream and a mixed catalyst to be regenerated; performing a first separation on the mixed reaction stream to obtain dry gas, light olefins and C 4 The above distillates, for the C 4 The above distillate oil is subjected to a second separation and the separated olefin-rich component is returned to the first reactor for further reaction; and the mixed catalyst to be regenerated by charring and the regenerated catalyst is returned to the first reactor and the second reactor respectively; preferably, the conditions of the second catalytic conversion reaction include: a reaction temperature of 500-600°C, preferably 530-580°C; a reaction pressure of 0.01-1MPa, preferably 0.05-1MPa; a reaction time of 0.01-80s, preferably 0.1-60s; a weight ratio of the second thermally regenerated catalyst to the heavy hydrocarbon oil of (1-100):1, preferably (3-50):1.

[0063] exist Figure 1 In the first reactor shown, the pre-lifting medium enters the first lifting section 2 through pipeline 1, and the first hot regenerated catalyst from the regeneration inclined tube 3 goes up under the action of the pre-lifting medium, and then enters the first catalytic conversion reaction zone 11 through the distribution action of the gas-solid mixed fluid distributor 5. The olefin-rich raw material is introduced into the first reactor through the pipeline 10 on the side of the first reactor, and enters the first catalytic conversion reaction zone under the action of the gas-solid mixed fluid distributor 5 to contact with the first hot regenerated catalyst to undergo catalytic cracking reaction. The additional first hot regenerated catalyst from the regenerator enters the first reactor from the bottom of the first catalytic conversion reaction zone through pipeline 7 to immediately supplement heat for the catalytic cracking reaction of the olefin-rich raw material. The cooling medium from other sections enters the annular fluid distributor 13 through pipeline 12 and enters the cooling zone 14 to take away part of the heat of the post-reaction logistics. The post-reaction logistics after cooling is accelerated through the second lifting section 15 and enters the subsequent catalyst separation system through the horizontal pipe 16.

[0064] In another specific embodiment, Figure 2 As shown, it is Figure 1The difference is that the olefin-rich raw material is introduced through the pipeline 4 on the side of the first lifting section 2, and enters the first catalytic conversion reaction zone 11 under the action of the gas-solid mixed fluid distributor 5 to contact the first thermal regeneration catalyst for catalytic cracking reaction. A heat supply 9 is provided in the first catalytic conversion reaction zone 11, and the heating medium is introduced into the heat supply 9 through the pipeline 6 to supplement the heat of the reaction system.

[0065] In another specific embodiment, Figure 3 As shown, the pre-lifting medium enters the first lifting section 2 through pipeline 1, and the first hot regenerated catalyst from the regeneration inclined tube 3 goes up under the action of the pre-lifting medium, and then enters the first catalytic conversion reaction zone 11 through the distribution action of the gas-solid mixed fluid distributor 5. The olefin-rich raw material is introduced into the first reactor through the pipeline 10 on the side of the first reactor, and enters the first catalytic conversion reaction zone under the action of the gas-solid mixed fluid distributor 5 to contact the first hot regenerated catalyst to undergo catalytic cracking reaction. The heating medium from other sections enters the heater 9 through pipeline 6 to immediately supplement heat for the reaction system to suppress the polymerization reaction of the olefin raw material under low temperature conditions; the cooling medium from other sections is introduced into the fluid distributor through pipeline 12 and enters the cooling zone 14 to quickly reduce the temperature of the reacted logistics. The reaction flow after cooling treatment is accelerated through the second lifting section 25 and enters the catalyst separation device. In the catalyst separation device, the post-reaction logistics enters the cyclone separator of the settler 26 to separate the first catalyst to be regenerated from the first reaction oil gas; after settling, the first catalyst to be regenerated flows to the stripping section 23, contacts with the stripping steam from the pipeline 22 to strip out the remaining reaction oil gas on the first catalyst to be regenerated, and the first catalyst to be regenerated after stripping enters the regenerator 29 via the pipeline 24 for char regeneration, and the regenerated first catalyst returns to the first reactor via the pipeline 3.

[0066] The first reaction oil and gas separated by the cyclone separator enters the gas collecting chamber 27, and then enters the distillation tower 31 through pipeline 28 for the first separation, the separated hydrogen, methane and ethane are led out through pipeline 32, ethylene is led out through pipeline 33, propylene is led out through pipeline 34, butene is led out through pipeline 35, propane and butane are led out through pipeline 36, and other components enter the alkane-olefin separation device 38 through pipeline 37 for the second separation, the separated olefin-free logistics is sent to the alkane processing device through pipeline 39, and the olefin-containing fraction is mixed with the olefin-rich raw material from pipeline 41 through pipeline 40 and returned to the first reactor to continue to participate in the reaction.

[0067] In another embodiment of the present invention, the catalytic cracking process of the heavy feedstock and the catalytic conversion process of the olefin-rich feedstock can be coupled. Figure 4, the pre-lifting medium enters the first lifting section 2 through pipeline 1, and the first hot regenerated catalyst from the regeneration inclined tube 3 goes up under the action of the pre-lifting medium, and then enters the first catalytic conversion reaction zone 11 through the distribution action of the gas-solid mixed fluid distributor 5. The olefin-rich raw material is introduced into the first reactor through the pipeline 10 on the side of the first reactor, and enters the first catalytic conversion reaction zone under the action of the gas-solid mixed fluid distributor 5 to contact the first hot regenerated catalyst for catalytic cracking reaction. The high-temperature regenerated catalyst from the regenerator enters the first reactor through pipeline 7 to immediately supplement heat for the reaction system. The reacted logistics is cooled in the cooling zone 14 by the cooling medium from pipeline 12 and enters the catalyst separation device through the second lifting section 15.

[0068] The pre-lifting medium enters the first lifting section 20 through pipeline 18 and moves upward together with the regenerated catalyst from pipeline 30. The heavy feedstock enters the second reactor through pipeline 19 and contacts the second hot regenerated catalyst to undergo a catalytic conversion reaction in the reaction zone of the second reactor. The reaction flow containing light oil obtained by the reaction has a temperature higher than 530°C. After being cooled by the cooling medium from pipeline 42, it enters the catalyst separation device through the outlet section 25.

[0069] In the catalyst separation device, the reacted flow from the first reactor is mixed with the reaction flow containing light oil from the second reactor and then enters the cyclone separator of the settler 26 to separate the regenerated catalyst from the reaction oil gas. After settling, the regenerated catalyst flows to the stripping section 23, contacts with the stripping steam from the pipeline 22, and then enters the regenerator 29 through the pipeline 24 for char regeneration. The regenerated catalyst is returned to the first reactor and the second reactor through the pipeline 3 and the pipeline 30 respectively.

[0070] The separated mixed reaction flow enters the gas collecting chamber 27 and is introduced into the distillation tower 31 through the pipeline 28 for the first separation, the separated hydrogen, methane and ethane are led out through the pipeline 32, ethylene is led out through the pipeline 33, propylene is led out through the pipeline 34, butene is led out through the pipeline 35, propane and butane are led out through the pipeline 36, and the other components enter the alkane-olefin separation device 38 through the pipeline 37 for the second separation, the separated olefin-free flow is sent to the alkane processing system through the pipeline 39, and the olefin-containing fraction is mixed with the olefin-rich feedstock from the pipeline 41 through the pipeline 40 and then enters the first reactor to continue the reaction.

[0071] The present invention is further described in detail by examples. The raw materials used in the examples can be obtained through commercial channels. Among them, the catalyst used in the examples and comparative examples is an industrial product produced by Qilu Branch of Sinopec Catalyst Co., Ltd., and the trade name is TCC-1. The properties of the heavy hydrocarbon oil I used are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] Example 1

[0076] This embodiment Figure 1 The fluidized bed catalytic conversion reaction device shown in the figure was tested, wherein the raw material was 1-hexene and the catalyst was TCC-1. The reaction raw material 1-hexene entered the fluidized bed catalytic conversion reaction device through the side feed pipeline of the reaction zone, and then entered the reaction zone through the feed fluid distributor, and contacted with the TCC-1 catalyst at 650°C to cause cracking reaction. The catalyst density in the reaction zone was 400kg / m 3 At the same time, the hot regeneration catalyst TCC-1 with a temperature of 700°C was additionally introduced into the bottom of the reactor. The reacted stream was cooled by the cooling medium introduced into the cooling zone. The weight ratio of the catalyst to 1-hexene was 30:1. The operating conditions and product distribution are shown in Table 2.

[0077] Example 2

[0078] This embodiment Figure 2 The fluidized bed catalytic conversion reaction device shown in the figure was tested, wherein the raw material was 1-hexene and the catalyst was TCC-1. The reaction raw material 1-hexene entered the fluidized bed catalytic conversion reaction device from the bottom feed pipeline of the reaction zone, and then entered the reaction zone through the annular gas-solid mixed fluid distributor, and contacted with the TCC-1 catalyst at 650°C to cause cracking reaction. The catalyst density in the reaction zone was 400kg / m 3 The heat was immediately supplemented by heaters on both sides of the reaction zone. The weight ratio of catalyst TCC-1 to 1-hexene was 30:1. The operating conditions and product distribution are shown in Table 2.

[0079] Comparative Example 1

[0080] This comparative example Figure 1 The fluidized bed catalytic conversion reaction device shown in the figure was tested, wherein the raw material was 1-hexene and the catalyst was TCC-1. The reaction raw material 1-hexene entered the fluidized bed catalytic conversion reaction device through the side feed pipeline of the reaction zone, entered the reaction zone through the annular gas-solid mixed fluid distributor, and contacted with the TCC-1 catalyst at 650°C to cause cracking reaction. The catalyst density in the reaction zone was 90kg / m 3 , and no supplementary heat and heat extraction equipment were set up. The weight ratio of catalyst TCC-1 and 1-hexene was 20:1. The operating conditions and product distribution are shown in Table 2.

[0081] Table 2

[0082]

[0083]

[0084] Example 3

[0085] This embodiment Figure 4 The reaction is carried out on the fluidized catalytic conversion reaction device shown in the figure. The reaction raw material of the first catalytic conversion reactor is 1-hexene, the reaction raw material of the second catalytic conversion reactor is heavy oil I, and the catalyst is TCC-1.

[0086] The raw material 1-hexene enters the first catalytic conversion reactor through the feed pipeline on the side of the reaction zone, and then enters the first catalytic conversion reaction zone through the annular gas-solid mixed fluid distributor, and contacts with the TCC-1 catalyst at 650°C for the first catalytic conversion reaction. The catalyst density in the reaction zone is 400kg / m 3 The reaction time was 0.5 s, and a hot regenerated catalyst at a temperature of 700° C. was introduced into the bottom of the reactor. The weight ratio of the catalyst TCC-1 to the raw material 1-hexene was 30:1.

[0087] Heavy oil I contacts the TCC-1 catalyst in the reaction zone of the second catalytic conversion reactor to undergo a catalytic conversion reaction to obtain a second reactant stream. The reaction temperature is 550° C., the reaction pressure is 0.2 MPa, the reaction time is 5 s, and the weight ratio of the catalytic conversion catalyst TCC-1 to the heavy oil I is 10:1.

[0088] The reaction conditions and product distribution are shown in Table 3.

[0089] Comparative Example 2

[0090] This comparative example Figure 4 The reaction is carried out on the catalytic conversion reaction device shown in the figure. The reaction raw material of the first catalytic conversion reactor is 1-hexene, the reaction raw material of the second catalytic conversion reactor is heavy oil I, and the catalyst is TCC-1.

[0091] The difference from Example 3 is that the hot regenerated TCC-1 catalyst is not injected into the bottom of the first catalytic conversion reactor, and no heat extraction equipment is set at the top. The reaction conditions and product distribution are shown in Table 3.

[0092] Table 3

[0093]

[0094] As shown in Tables 2 and 3, the method of the present invention suppresses the polymerization reaction of olefin raw materials under low temperature conditions to a certain extent by instantly supplementing heat to the reaction zone of the fluidized bed catalytic conversion reaction device, reduces the production of large molecular olefin products, and improves the selectivity and yield of low-carbon olefin products, especially high value-added products such as ethylene.

[0095] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0096] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0097] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing light olefins, characterized in that: The method comprises the following steps: The olefin-rich feedstock is brought into contact with a first thermally regenerated catalyst, and a first catalytic conversion reaction is carried out in a dense phase fluidized bed of a first reactor equipped with an instant heat replenishment system. The post-reaction logistics is rapidly cooled in a cooling zone near the top of the first reactor, and the post-reaction logistics is cooled to a target temperature of 450-530°C before being sent out of the first reactor.

2. The method according to claim 1, wherein: The instant heat supplement system comprises a catalyst supplement pipe for introducing additional hot regenerated catalyst into the dense fluidized bed, or the instant heat supplement system comprises a heat supplier arranged in the dense fluidized bed of the first reactor; The heating medium in the heater is at least one of high-temperature steam and steam cracking gas.

3. The method according to claim 2, wherein: The mass ratio of the regenerated catalyst to the olefin-rich feedstock is (1-100):1, preferably (10-50):

1.

4. The method according to claim 1, wherein the temperature of the post-reaction logistics is reduced to the target temperature after the post-reaction logistics is cooled within 0.5-2 seconds, preferably within 0.5-1 second.

5. The method according to claim 1, wherein: The catalyst density of the first thermally regenerated catalyst in the dense phase fluidized bed of the first reactor is 100-700 kg / m 3 , preferably 300-600kg / m 3 , more preferably 400-500kg / m 3 .

6. The method according to claim 1, wherein: The first reactor comprises, from bottom to top, a first lifting section, an expansion section, a dense phase fluidization section, a reduction section, and a second lifting section; the angle between the side wall of the expansion section and the axis is 5-60 degrees; the ratio of the diameter to the height of the dense phase fluidization section is (0.1-10):1; the angle between the side wall of the reduction section and the axis is 5-60 degrees; The head of the first lifting section is provided with a first heat regeneration catalyst inlet and a lifting medium inlet; A raw material inlet is provided in the middle of the first lifting section; A gas-solid mixed fluid distributor is also provided at the tail of the first lifting section; The cooling zone is arranged at the tail of the dense phase fluidization section; Preferably, the cooling zone is provided with a plurality of fluid distributors for introducing the coolant, and the fluid distributors are arranged in a ring shape along the circumference of the first reactor; Preferably, the cooling medium is a coolant and / or a cooled regenerated catalyst; the coolant is selected from at least one of liquefied gas, crude gasoline, stabilized gasoline, diesel, heavy diesel, water and olefins with eight or more carbon atoms.

7. The method according to claim 1, wherein: The conditions of the first catalytic conversion reaction include: a reaction temperature of 550-750°C, preferably 600-750°C, and more preferably 650-700°C; a reaction pressure of 0.1-1MPa, preferably 0.1-0.7MPa; a reaction time of 0.2-10s, preferably 0.2-0.5s; a weight ratio of the first thermally regenerated catalyst to the olefin-rich feedstock of (1-100):1, preferably (5-50):1; Preferably, the content of C4-C8 olefins in the olefin-rich feedstock is 50-100wt%, preferably 80-100wt%, and more preferably 90-100wt%; Preferably, the olefin-rich raw material is selected from one or more of the C4 and above fractions produced by an alkane dehydrogenation unit, the C4 and above fractions produced by a catalytic cracking unit in a refinery, the C4 and above fractions produced by a steam cracking unit in an ethylene plant, the C4 and above olefin-rich fractions produced as a by-product of MTO, and the C4 and above olefin-rich fractions produced as a by-product of MTP.

8. The method according to claim 1, wherein: Based on the total weight of the first thermally regenerated catalyst, the first thermally regenerated catalyst comprises 1-50 wt% of molecular sieve, 5-99 wt% of inorganic oxide and 0-70 wt% of clay; The silicon-aluminum ratio of the molecular sieve is 10-1000; The molecular sieve is selected from one or more of the ZSM-5 series molecular sieves and the SAPO series molecular sieves; preferably the medium-pore ZSM-5 series molecular sieves; The inorganic oxide is selected from one or more of silicon dioxide and aluminum oxide; the clay is selected from one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite.

9. The method according to claim 1, wherein: The method further comprises the following steps: subjecting the post-reaction logistics to gas-solid separation to obtain reaction oil gas containing olefins and a first spent catalyst, and then charring the first spent catalyst and returning it to the first reactor.

10. The method according to claim 1, wherein: The method further comprises the following steps: The heavy hydrocarbon oil is contacted with a second heat-regenerated catalyst in a second reactor to perform a second catalytic conversion reaction to obtain a reaction stream containing light oil, and when the temperature of the reaction stream containing light oil in the upper region of the reaction zone of the second catalytic conversion reactor exceeds 530° C., a cooling zone is provided downstream of the reaction zone to cool the reaction stream containing light oil to below 530° C.; The cooled light oil-containing reaction stream is mixed with the reaction stream, and the catalyst is separated from the mixed stream to obtain a mixed reaction stream and a mixed catalyst to be produced; Performing a first separation on the mixed reaction stream to obtain dry gas, light olefins and C4 and above distillates, performing a second separation on the C4 and above distillates and returning the separated olefin-rich components to the first reactor for further reaction; and Carrying out char regeneration on the mixed spent catalyst and returning the regenerated catalyst to the first reactor and the second reactor respectively; Preferably, the conditions of the second catalytic conversion reaction include: reaction temperature of 500-600°C, preferably 530-580°C; reaction pressure of 0.01-1MPa, preferably 0.05-1MPa; reaction time of 0.01-80s, preferably 0.1-60s; weight ratio of the second thermal regeneration catalyst to the heavy hydrocarbon oil is (1-100):1, preferably (3-50):1.

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