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 first thermal regeneration catalyst, and carrying out first catalytic conversion reaction in a dense-phase fluidized bed layer of a first catalytic conversion reactor, and the reacted material flow is in contact with a heat collector arranged above the reaction area in the first catalytic conversion reactor for rapid cooling, 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 catalytic conversion reactor. According to the present invention, the olefin-rich raw material is contacted with the hot regeneration catalyst, the reaction is performed in the dense phase fluidized bed layer, and the reacted material flow is rapidly cooled in the cooling zone through the cooling medium, such that the control on the catalytic cracking reaction and the thermal cracking reaction is optimized, the deep reaction in the reaction process can be effectively inhibited, and the product quality is improved. The yield and the selectivity of the low-carbon olefin 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 generally refer to ethylene, propylene and butene, which are important chemicals in the petrochemical industry. They are mainly used in the production of organic chemical raw materials and in the preparation of fine chemicals such as synthetic resins and synthetic rubber.

[0003] The technologies for producing low-carbon olefins from petroleum as raw materials include steam cracking, catalytic cracking, alkane dehydrogenation and olefin disproportionation. The traditional method for producing low-carbon olefins is to produce ethylene and propylene through steam cracking. This typical process consumes a large amount of light hydrocarbons or chemical light hydrocarbons such as naphtha. However, the quality of domestic crude oil is relatively heavy, and the production capacity of chemical light oil is insufficient to meet the demand for producing low-carbon olefin raw materials. In addition, the existing steam cracking process for producing low-carbon olefins has high energy consumption, low olefin product yield, and a large proportion of dry gas in the product.

[0004] In this regard, CN114763483A provides a catalytic conversion method for producing ethylene and propylene from olefin-rich raw materials. Compared with the traditional cracking of alkane raw materials to produce low-carbon olefins, high-temperature cracking of olefin-rich raw materials can effectively increase the yield of ethylene and propylene and reduce the selectivity of methane in the product.

[0005] In order to meet the needs of the petrochemical industry while taking into account the goal of improving quality and efficiency of enterprises, the field has developed a process route for cracking high-carbon olefins with carbon atoms greater than or equal to 4 in the refinery process to produce low-carbon olefins. However, the yield and selectivity of low-carbon olefins in the existing process still need to be further improved. Summary of the invention

[0006] The object of the present invention is to further improve the yield of light olefins in the cracking process of olefin-containing raw materials.

[0007] In order to achieve the above object, the present invention provides a method for preparing light olefins, which comprises the following steps:

[0008] The olefin-rich feedstock is brought into contact with the first thermally regenerated catalyst and a first catalytic conversion reaction is carried out in the dense fluidized bed of the first catalytic conversion reactor. The post-reaction logistics is brought into contact with a heat collector disposed above the reaction zone in the first catalytic conversion reactor for rapid cooling. The post-reaction logistics is cooled to a target temperature of 450-530°C and then sent out of the first catalytic conversion reactor.

[0009] Optionally, the reacted logistics is cooled to the target temperature 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 catalytic conversion reactor is 100-700 kg / m 3 , preferably 300-600kg / m 3 , more preferably 400-500kg / m 3 .

[0011] Optionally, the first catalytic conversion 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 (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

[0012] Optionally, the heat exchanger is arranged along the circumference of the tail of the first catalytic conversion reactor; the cooling medium in the heat exchanger 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.

[0013] Optionally, the conditions of the catalytic cracking reaction include: a reaction temperature of 500-800°C, preferably 600-700°C, and further preferably 650-700°C; a reaction time of 0.1-20s, preferably 0.1-10s, and further preferably 0.2-0.5s; a reaction pressure of 0.05-2MPa, preferably 0.1-0.6MPa; and a weight ratio of the first thermally regenerated catalyst to the olefin-rich feedstock of (1-200):1, preferably (10-100):1.

[0014] Optionally, the olefin-rich feedstock is a gaseous feed; 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 feedstock is selected from the fractions with a carbon number of four or more produced by alkane dehydrogenation, crude oil catalytic cracking, ethylene steam cracking, MTO and MTP.

[0015] Optionally, based on the total weight of the first thermally regenerated catalyst, the catalyst comprises 1-50 wt% of molecular sieves, 5-99 wt% of inorganic oxides and 0-70 wt% of clay; the molecular sieves are selected from one or more of ZSM-5 series molecular sieves and SAPO series molecular sieves; the inorganic oxides are selected from one or more of silica and alumina; the clay is selected from one or more of kaolin and halloysite.

[0016] Optionally, the method further includes the following steps: subjecting the post-reaction logistics to gas-solid separation to obtain a first reaction oil gas and a first regenerated catalyst, then charring and regenerating the first regenerated catalyst, and returning the obtained regenerated catalyst to the first catalytic conversion reactor.

[0017] Optionally, the method further comprises the following steps: contacting the heavy feedstock with a second thermally regenerated catalyst in a second catalytic conversion reactor for a second catalytic conversion reaction to obtain a reaction oil gas containing light oil and a second catalyst to be regenerated; when the temperature of the reaction oil gas containing light oil and the second catalyst to be regenerated in the middle and upper area of ​​the reaction zone of the second catalytic conversion reactor exceeds 530°C, a cooling zone is provided downstream of the reaction zone, and the reaction oil gas containing light oil and the second catalyst to be regenerated are cooled to below 530°C; then the cooled reaction oil gas containing light oil and the second catalyst to be regenerated are mixed with the reacted flow, and the obtained mixed flow is subjected to a first separation to obtain a reaction flow containing light olefins and a catalyst to be regenerated; distilling the reaction flow containing light olefins to separate dry gas, light olefins and C4 and above fractions, performing a second separation on the C4 and above fractions and returning the separated olefin-rich components to the first catalytic conversion reactor; and charring and regenerating the catalyst to be regenerated and returning the regenerated catalyst to the first catalytic conversion reactor and the second catalytic conversion reactor.

[0018] Through the above technical scheme, the present invention optimizes the control of catalytic cracking reaction and thermal cracking reaction by bringing the olefin-rich raw material into contact with the hot regenerated catalyst and reacting in a dense fluidized bed, and then rapidly cooling the post-reaction logistics in a cooling zone through a cooling medium, thereby effectively inhibiting the deep reaction in the reaction process and improving 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 catalytic conversion reactor provided by the present invention.

[0022] Figure 2 A schematic diagram of another embodiment of the first catalytic conversion 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 Feed pipeline 5 Gas-solid mixed fluid distributor 6 Feed fluid distributor

[0028] 7 first catalytic conversion reaction zone 8 pipeline 9 heat collector

[0029] 10 Cooling zone 11 Second lifting section 12 Horizontal pipe

[0030] 13 pipeline 14 pipeline 15 pipeline

[0031] 16 Riser 17 Second catalytic conversion reaction zone 18 Pipeline

[0032] 19 stripping section 20 pipeline 21 outlet pipe

[0033] 22 settler 23 gas collecting chamber 24 pipeline

[0034] 25 regenerator 26 pipeline 27 fractionation tower

[0035] 28 pipeline 29 pipeline 30 pipeline

[0036] 31 pipeline 32 pipeline 33 pipeline

[0037] 34 Alkane-Olefin Separation Unit 35 Pipeline 36 Pipeline

[0038] 37 pipeline 38 pipeline DETAILED DESCRIPTION

[0039] 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.

[0040] 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 catalytic conversion reactor, contacting the post-reaction logistics with a heat collector disposed above a reaction zone in the first catalytic conversion reactor for rapid cooling, and cooling the post-reaction logistics to a target temperature of 450-530°C before sending the first catalytic conversion reactor.

[0041] The present invention optimizes the control of catalytic cracking reaction and thermal cracking reaction by bringing the olefin-rich raw material into contact with the heat-regenerated catalyst and reacting in a dense phase fluidized bed, and then rapidly cooling the post-reaction logistics in a cooling zone via a cooling medium, thereby effectively inhibiting the deep reaction in the reaction process and improving the yield and selectivity of light olefins.

[0042] The post-reaction logistics is cooled to the target temperature within 0.5-2 seconds, preferably within 0.5-1 second.

[0043] The catalyst density of the first thermally regenerated catalyst in the dense phase fluidized bed of the first catalytic conversion reactor is 100-700 kg / m 3 , preferably 300-600kg / m 3 , more preferably 400-500kg / m 3 .

[0044] The first catalytic conversion 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 (1-10): 1; the angle between the side wall of the reduction section and the axis is 5-60 degrees. For example, it can be 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, or other values ​​within the above range.

[0045] Among them, 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.

[0046] Preferably, the heat exchanger is arranged along the circumference of the tail of the first catalytic conversion reactor; the cooling medium in the heat exchanger 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.

[0047] Among them, the conditions of the first catalytic conversion reaction include: reaction temperature of 500-800°C, preferably 600-700°C, and more preferably 650-700°C; reaction time of 0.1-20s, preferably 0.1-10s, and more preferably 0.2-0.5s; reaction pressure of 0.05-2MPa, preferably 0.1-0.6MPa; the weight ratio of the first thermal regeneration catalyst to the olefin-rich feedstock is (1-200):1, preferably (10-100):1.

[0048] Wherein, the olefin-rich raw material is a gaseous feed; the content of C4-C8 olefins in the olefin-rich raw material is 50-100wt%, preferably 80-100wt%, and more preferably 90-100wt%; preferably, the olefin-rich raw material is selected from the fractions with a carbon number of four or more produced by alkane dehydrogenation, crude oil catalytic cracking, ethylene steam cracking, MTO and MTP.

[0049] Wherein, based on the total weight of the first thermally regenerated catalyst, the catalyst includes 1-50 weight % of molecular sieves, 5-99 weight % of inorganic oxides and 0-70 weight % of clay; the molecular sieve is selected from one or more of ZSM-5 series molecular sieves and SAPO 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 and halloysite.

[0050] The method further comprises the following steps: performing gas-solid separation on the post-reaction logistics to obtain a first reaction oil gas and a first spent catalyst, then charring and regenerating the first spent catalyst, and returning the obtained regenerated catalyst to the first catalytic conversion reactor.

[0051] The method further comprises the following steps: contacting the heavy feedstock with a second thermally regenerated catalyst in a second catalytic conversion reactor to perform a second catalytic conversion reaction to obtain a reaction gas containing light oil and a second catalyst to be regenerated; when the temperature of the reaction gas containing light oil and the second catalyst to be regenerated 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, and cooling the reaction gas containing light oil and the second catalyst to be regenerated to below 530° C.;

[0052] Then, the cooled reaction oil gas containing light oil, the second catalyst to be regenerated and the post-reaction flow are mixed, and the obtained mixed flow is subjected to a first separation to obtain a reaction flow containing light olefins and a catalyst to be regenerated; the reaction flow containing light olefins is distilled to separate dry gas, light olefins and C4 and above fractions, and the C4 and above fractions are subjected to a second separation and the separated olefin-rich components are returned to the first catalytic conversion reactor; and the catalyst to be regenerated is subjected to charring and the regenerated catalyst is returned to the first catalytic conversion reactor and the second catalytic conversion reactor.

[0053] Figure 1 The first catalytic conversion reactor of a specific embodiment of the present invention is shown below. Figure 1 The first catalytic conversion reactor of the present invention is specifically described. The pre-lifting medium enters the first lifting section 2 through the pipeline 1, and moves upward together with the first hot regeneration catalyst from the regeneration inclined tube 3. The preheated olefin-rich raw material is introduced from the first lifting section through the feed pipeline 4, and enters the first catalytic conversion reaction zone 7 after being distributed by the gas-solid mixed fluid distributor 5. The preheated olefin-rich raw material contacts the first hot regeneration catalyst in the first catalytic conversion reaction zone 7 to undergo catalytic cracking reaction to obtain the reacted logistics. The cooling medium from other sections is introduced into the heat collector 9 provided in the cooling zone 10 through the pipeline 8. The reacted logistics contacts the heat collector for cooling. The reacted logistics with part of the heat removed is accelerated by the second lifting section 11 and enters the subsequent catalyst separation device through the horizontal pipe 12.

[0054] like Figure 2 As shown, in another specific embodiment of the present invention, it is Figure 1 The difference between the processes shown is that the feed position of the olefin-rich raw material is different. The olefin-rich raw material is introduced through the feed pipeline 4 on the side of the first catalytic conversion reaction zone, and under the distribution of the feed fluid distributor 6, the olefin-rich raw material is fully contacted with the first thermally regenerated catalyst with a temperature of more than 650° C. to carry out the first catalytic conversion reaction.

[0055] Figure 3 A specific implementation of the method of the present invention is shown. Figure 3In the process, the pre-lifting medium passes through the first lifting section 2 via pipeline 1, and the first hot regenerated catalyst from the regeneration inclined tube 3 goes up under the lifting effect of the pre-lifting medium. The preheated olefin-rich raw material is introduced from the first lifting section of the first catalytic conversion reactor via the feed pipeline 4, and then enters the first catalytic conversion reaction zone 7 through the action of the feed fluid distributor, and contacts with the first hot regenerated catalyst in the first catalytic conversion reaction zone 7 to catalyze the first catalytic conversion reaction. The cooling medium from other sections is introduced into the heat collector 9 provided in the cooling zone 10 via pipeline 8, and the reacted logistics contacts with the heat collector for cooling. The reacted logistics, which has part of the heat removed by the cooling medium in the heat collector, is accelerated through the second lifting section and enters the catalyst separation device.

[0056] In the catalyst separation device, the post-reaction logistics enters the cyclone separator of the settler 22 for separation, and the separated first spent catalyst enters the stripping section 19, contacts with the stripping steam from the pipeline 18 to strip out the remaining reaction oil and gas on the spent catalyst, and the first spent catalyst after stripping enters the regenerator 25 through the pipeline 20 for regeneration treatment, and the charred regenerated first thermally regenerated catalyst returns to the first catalytic conversion reactor through the pipeline 3.

[0057] The separated first reaction oil and gas containing low-carbon olefins enters the distillation tower 27 through pipeline 24 for the first separation, the separated hydrogen, methane and ethane are led out through pipeline 28, ethylene is led out through pipeline 29, propylene is led out through pipeline 30, butene is led out through pipeline 31, propane and butane are led out through pipeline 32, and the other components enter the alkane-olefin separation device 34 through pipeline 33 for the second separation, the separated olefin-free logistics leaves the reaction system through pipeline 35, and the separated olefin product is returned to the first catalytic conversion reactor through pipeline 36 and the olefin-rich feedstock from pipeline 37 for further reaction.

[0058] Figure 4 Another specific embodiment of the present invention is shown. Figure 4 In the process, the pre-lifting medium enters the first lifting section 2 of the first catalytic conversion reactor through pipeline 1, the first hot regenerated catalyst from the regeneration inclined tube 3 goes up under the action of the pre-lifting medium, the olefin-rich feedstock enters the first catalytic conversion reaction zone 7 through pipeline 4 and contacts with the first hot regenerated catalyst to carry out the first catalytic conversion reaction, and the post-reaction logistics enters the catalyst separation device through the second lifting section 11 after being cooled in contact with the heat collector 9 in the cooling zone 10.

[0059] The pre-lifting medium enters the lifting pipe 16 through the pipeline 14, and goes up to the second catalytic conversion reaction zone 17 together with the second thermally regenerated catalyst from the pipeline 26. The heavy hydrocarbon oil feedstock enters the second catalytic conversion reaction zone 17 through the pipeline 15, contacts with the second thermally regenerated catalyst, and undergoes a second catalytic conversion reaction. The reaction oil gas containing light oil and the second catalyst to be regenerated obtained by the reaction in the second catalytic conversion reactor are cooled by the cooling medium from the pipeline 38 when the temperature is higher than 530°C, and then enter the catalyst separation device through the outlet pipe 21. In the catalyst separation device, the reacted flow from the first catalytic conversion reactor is mixed with the reaction oil gas containing light oil and the second catalyst to be regenerated from the second catalytic conversion reactor, and then enters the cyclone separator of the settler 22 for the first separation, so as to separate the catalyst to be regenerated from the reaction product. The separated regenerated catalyst enters the stripping section 19 and contacts with the stripping steam from the pipeline 18 to strip out the remaining reaction oil and gas on the catalyst. The regenerated catalyst after stripping enters the regenerator 25 for charring regeneration. The regenerated catalyst after charring treatment returns to the first catalytic conversion reactor and the second catalytic conversion reactor via the pipeline 3 and the pipeline 26 respectively.

[0060] The separated olefin-containing reaction stream enters the distillation tower 27 via pipeline 24 for the first separation, the separated hydrogen, methane and ethane are led out via pipeline 28, ethylene is led out via pipeline 29, propylene is led out via pipeline 30, butene is led out via pipeline 31, propane and butane are led out via pipeline 32, and the other components enter the alkane-olefin separation device 34 via pipeline 33 to enter the second separation, the olefin-free stream leaves the reaction system via pipeline 35, and the separated olefin-rich component is mixed with the olefin-rich feedstock from pipeline 37 via pipeline 36 and returned to the first catalytic conversion reactor to continue the reaction.

[0061] 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 commercial brand of the catalyst used in the examples and comparative examples is TCC-1, which is an industrial product produced by the Qilu Branch of Sinopec Catalyst Co., Ltd. The properties of the heavy hydrocarbon oil I used are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] Example 1

[0066] This embodiment follows Figure 3 The process shown is tested on a medium-sized device of the first catalytic conversion reactor, the reaction raw material is 1-octene, and the catalyst is TCC-1. The structural parameters of the first catalytic conversion reactor include:

[0067] The total height of the first lifting section, expansion section, dense phase fluidization section, reduction section and second lifting section is 11.5 meters, among which the diameter of the first lifting section is 0.25 meters and the height is 1.5 meters; the angle between the side wall of the expansion section and the axis is 45 degrees, and the height of the expansion section is 1 meter; the diameter of the dense phase fluidization section is 2.5 meters and the height is 5 meters; the angle between the side wall of the reduction section and the axis is 45 degrees, and the height is 1.0 meter; the diameter of the second lifting section is 0.5 meters and its height is 3 meters.

[0068] The raw material 1-octene enters the first catalytic conversion reactor from the feed pipeline at the bottom of the reaction zone, enters the reaction zone through the gas-solid mixed fluid distributor, and contacts with the TCC-1 catalyst in the reaction zone for catalytic cracking reaction. The catalyst density in the reaction zone is 400kg / m 3 , reaction temperature is 650℃, reaction pressure is 0.2MPa, reaction time is 0.5s, weight ratio of catalyst TCC-1 and 1-octene is 30:1, and the post-reaction flow is cooled by cooling medium in the heat exchanger in the cooling zone. Reaction conditions and product distribution are shown in Table 2.

[0069] Comparative Example 1

[0070] This comparative ratio is based on Figure 3 The process shown was tested on a medium-sized device for catalytic conversion reaction, the reaction raw material was 1-octene, and the catalyst was TCC-1. The reaction process of Comparative Example 1 is similar to that of Example 1, except that the structure of the catalytic conversion reaction device is different. Among them, the structural parameters of the first catalytic conversion reactor include:

[0071] The total height of the first lifting section, expansion section, dense phase fluidization section, reduction section and second lifting section of the reactor is 15.5 meters, among which the diameter of the first lifting section is 0.5 meters and the height is 1.5 meters; the angle between the side wall of the expansion section and the axis is 45 degrees, and the height of the expansion section is 0.5 meters; the diameter of the dense phase fluidization section is 1.5 meters and the height is 10 meters; the angle between the side wall of the reduction section and the axis is 45 degrees, and the height of the reduction section is 0.5 meters; the diameter of the second lifting section is 0.5 meters and the height is 3 meters.

[0072] The raw material 1-octene enters the first catalytic conversion reactor from the feed pipeline at the bottom of the reaction zone, enters the reaction zone through the gas-solid mixed fluid distributor, and contacts with the hot TCC-1 catalyst to undergo catalytic cracking reaction. The catalyst density in the reaction zone is 90 kg / m 3 , and no heat collector was set, and the weight ratio of catalyst TCC-1 and 1-octene was 20:1. The reaction conditions and product distribution are shown in Table 2.

[0073] Table 2

[0074]

[0075]

[0076] Example 2

[0077] This embodiment refers to Figure 4 The process shown in the figure was used for the experiment. The reaction raw material of the first catalytic conversion reactor was 1-octene, the raw material of the second catalytic conversion reactor was heavy oil I, and the catalyst was TCC-1.

[0078] The raw material 1-octene enters the first catalytic conversion reactor from the feed pipeline on the side of the reaction zone of the first catalytic conversion reactor, enters the reaction zone through the annular gas-solid mixed fluid distributor, and contacts with the hot TCC-1 catalyst in the reaction zone of the first catalytic conversion reactor for catalytic cracking reaction. The catalyst density in the reaction zone is 400kg / m 3 The reaction temperature is 600°C, the reaction pressure is 0.2MPa, the reaction time is 0.3s, the weight ratio of catalyst TCC-1 and 1-octene is 30:1, and the post-reaction logistics is cooled in the cooling zone by the cooling medium in the heat exchanger.

[0079] Heavy oil I contacts and reacts with TCC-1 catalyst in the reaction zone of the second catalytic conversion reactor to obtain a second reaction flow; wherein the reaction temperature is 560°C, the reaction pressure is 0.2MPa, the reaction time is 5s, and the weight ratio of the catalytic conversion catalyst TCC-1 to the heavy oil I is 10:1.

[0080] The reaction conditions and product distribution are shown in Table 3.

[0081] Comparative Example 2

[0082] This comparative example refers to Figure 4 The process shown in the figure is used for the test, the reaction raw material of the first catalytic conversion reactor is 1-octene, the raw material of the second catalytic conversion reactor is heavy oil I, and the catalyst is TCC-1. The difference between Comparative Example 2 and Example 2 is that no cooling medium is introduced into the heat extractor in the cooling zone to remove heat.

[0083] The raw material 1-octene enters the first catalytic conversion reactor from the feed pipeline on the side of the reaction zone of the first catalytic conversion reactor, enters the reaction zone through the annular gas-solid mixed fluid distributor, and contacts with the hot TCC-1 catalyst in the reaction zone of the cracking reactor for catalytic cracking reaction. The catalyst density in the reaction zone is 90kg / m 3 , and no heat collector is set, the reaction temperature is 600°C, the reaction pressure is 0.2MPa, the reaction time is 0.3s, and the weight ratio of catalyst TCC-1 and 1-octene is 20:1.

[0084] Heavy oil I contacts and reacts with TCC-1 catalyst in the reaction zone of the second catalytic conversion reactor to obtain a second reaction flow; wherein the reaction temperature is 560°C, the reaction pressure is 0.2MPa, the reaction time is 5s, and the weight ratio of the catalytic conversion catalyst TCC-1 to the heavy oil I is 10:1.

[0085] Table 3

[0086]

[0087]

[0088] In summary, it can be seen from the data in Table 2 and Table 3 that the method provided by the present invention can significantly increase the content of light olefins in the product of the cracking reaction of olefin-rich raw materials by increasing the catalyst bed density and shortening the residence time of the reactants; the introduction of the cooling medium in the heat extractor can significantly inhibit the occurrence of side reactions such as thermal cracking and secondary reactions by quickly lowering the temperature of the reaction materials; the coupling of the heavy raw material cracking process with the olefin-rich raw material cracking process also optimizes the entire process flow and improves the raw material utilization efficiency.

[0089] 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.

[0090] 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.

[0091] 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 the first thermally regenerated catalyst and a first catalytic conversion reaction is carried out in the dense fluidized bed of the first catalytic conversion reactor. The post-reaction logistics is brought into contact with a heat collector disposed above the reaction zone in the first catalytic conversion reactor for rapid cooling. The post-reaction logistics is cooled to a target temperature of 450-530°C and then sent out of the first catalytic conversion reactor.

2. The method according to claim 1, wherein: The reacted logistics is cooled to the target temperature within 0.5-2 seconds, preferably within 0.5-1 second.

3. 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 catalytic conversion reactor is 100-700 kg / m 3 , preferably 300-600kg / m 3 , more preferably 400-500kg / m 3 .

4. The method according to claim 1, wherein: The first catalytic conversion 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 (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.

5. The method according to claim 1, wherein: The heat collector is arranged along the circumference of the tail of the first catalytic conversion reactor; The cooling medium in the heat collector 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.

6. The method according to claim 1, wherein: The conditions of the first catalytic conversion reaction include: reaction temperature of 500-800°C, preferably 600-700°C, more preferably 650-700°C; reaction time of 0.1-20s, preferably 0.1-10s, more preferably 0.2-0.5s; reaction pressure of 0.05-2MPa, preferably 0.1-0.6MPa; The weight ratio of the first thermally regenerated catalyst to the olefin-rich feedstock is (1-200):1, preferably (10-100):

1.

7. The method according to claim 1, wherein: The olefin-rich raw material is a gas phase feed; The content of C4-C8 olefins in the olefin-rich raw material is 50-100wt%, preferably 80-100wt%, and more preferably 90-100wt%; Preferably, the olefin-rich feedstock is selected from the fractions with a carbon number of four or more produced by alkane dehydrogenation, crude oil catalytic cracking, ethylene steam cracking, MTO and MTP.

8. The method according to claim 1, wherein: Based on the total weight of the first thermally regenerated catalyst, the catalyst comprises 1-50 wt% of a molecular sieve, 5-99 wt% of an inorganic oxide and 0-70 wt% of clay; The molecular sieve is one or more of a ZSM-5 series molecular sieve and a SAPO 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 and halloysite.

9. The method according to claim 1, wherein: The method also includes the following steps: subjecting the post-reaction logistics to gas-solid separation to obtain a first reaction oil gas and a first spent catalyst, then charring and regenerating the first spent catalyst, and returning the obtained regenerated catalyst to the first catalytic conversion reactor.

10. The method according to claim 1, wherein: The method further comprises the following steps: contacting the heavy feedstock with a second thermally regenerated catalyst in a second catalytic conversion reactor to perform a second catalytic conversion reaction to obtain a reaction gas containing light oil and a second catalyst to be regenerated; when the temperature of the reaction gas containing light oil and the second catalyst to be regenerated in the middle and upper region of the reaction zone of the second catalytic conversion reactor exceeds 530° C., providing a cooling zone downstream of the reaction zone, and cooling the reaction gas containing light oil and the second catalyst to be regenerated to below 530° C.; Then, the cooled reaction oil gas containing light oil, the second catalyst to be regenerated and the post-reaction stream are mixed, and the obtained mixed stream is subjected to a first separation to obtain a reaction stream containing light olefins and a catalyst to be regenerated; The reaction flow containing light olefins is distilled to separate dry gas, light olefins and C4 and above distillates, the C4 and above distillates are subjected to a second separation and the separated olefin-rich components are returned to the first catalytic conversion reactor; and the spent catalyst is charred and regenerated and the regenerated catalyst is returned to the first catalytic conversion reactor and the second catalytic conversion reactor.

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