CN119528671A - A method for preparing light olefins - Google Patents

Abstract

The invention relates to a method for preparing low-carbon olefin, which comprises the following steps of enabling raw materials rich in olefin to be in contact with a thermal regeneration catalyst, carrying out a first catalytic conversion reaction in a dense-phase fluidized bed layer of a first reactor provided with an instant energy supplementing system, enabling reacted materials to flow through a cooling zone near the upper part in the first reactor for rapid cooling, enabling the reacted materials to be cooled to a target temperature of 450-530 ℃, and then sending the materials out of the first reactor. According to the invention, the heat is instantly supplemented for the dense-phase fluidized bed layer, so that the raw material rich in olefin 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, the light raw material is promoted to carry out single-molecule cracking reaction, and the yield and selectivity of low-carbon olefin with high added value such as ethylene in the obtained product are improved.

Description

Method for preparing low-carbon olefin

Technical Field

The invention belongs to the field of petrochemical industry, and particularly relates to a method for preparing low-carbon olefin.

Background

The low-carbon olefin represented by ethylene and propylene is a basic raw material in the chemical industry, and can be used for producing synthetic resin, rubber and various fine chemical products. At present, natural gas or light petroleum fractions are mostly used as raw materials to produce low-carbon olefins by adopting a steam cracking process, while domestic crude oil is generally heavy, and the yield of light hydrocarbon oil is difficult to meet the raw material requirements. Moreover, the steam cracking technology has the limitations of high energy consumption, high production cost, difficult regulation of product structure and the like after years of development and continuous perfection.

In order to meet the requirements of petrochemical industry, a process for preparing low-carbon olefins by cracking high-carbon olefins in a refinery is currently developed in the art, for example, CN114763483a discloses a catalytic conversion method for preparing ethylene and propylene from an olefin-rich raw material, which effectively improves the yield of ethylene and propylene and can reduce the methane selectivity in the product by cracking the olefin-rich raw material at high temperature. CN101092323a discloses a method for preparing ethylene and propylene, which uses olefin of C ₄-C₈ as raw material to make catalytic cracking, separates the product after the reaction is completed, returns the separated C ₄ fraction to the reactor to make cracking, and improves the conversion rate of olefin by recycling the C ₄ fraction.

However, the yield and selectivity of the low-carbon olefin are still low in the actual production.

Disclosure of Invention

The invention aims to further improve the yield and selectivity of low-carbon olefin.

In order to achieve the above object, the present invention provides a process for producing light olefins, comprising the steps of contacting an olefin-rich feedstock 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 supplementing system, wherein the reacted stream is rapidly cooled by a cooling zone near the upper part of the first reactor, and the reacted stream is cooled to a target temperature of 450-530 ℃ and then fed out of the first reactor.

Optionally, the instant heat supplementing system comprises a catalyst supplementing pipe for introducing additional heat into the dense-phase fluidized bed layer of the regenerated catalyst, or comprises a heater arranged in the dense-phase fluidized bed layer of the first reactor, wherein a heating medium in the heater is at least one of high-temperature steam and steam cracking gas.

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

Optionally, the reacted stream is cooled down to the target temperature of the cooled down reacted stream within 0.5-2 seconds, preferably within 0.5-1 second.

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

Optionally, the first reactor comprises a first lifting section, an expanding section, a dense-phase fluidization section, a reducing section and a second lifting section from bottom to top, wherein the included angle between the side wall of the expanding section and the axis is 5-60 degrees, the ratio of the diameter of the dense-phase fluidization section to the height is (0.1-10) 1, the included angle between the side wall of the reducing section and the axis is 5-60 degrees, the head of the first lifting section is provided with a first thermal regeneration catalyst inlet and a lifting medium inlet, the middle part of the first lifting section is provided with a raw material inlet, the tail part of the first lifting section is further provided with a gas-solid mixed fluid distributor, the cooling zone is arranged at the tail part of the dense-phase fluidization section, preferably, the cooling zone is provided with a plurality of fluid distributors for introducing the cooling agent, and the fluid distributors are annularly arranged along the circumferential direction of the first reactor, preferably, the cooling medium is a cooling agent and/or a cooled regeneration catalyst, and the cooling agent is selected from gas, diesel oil, stable diesel oil, heavy gasoline, and at least one of eight carbon atoms and at least one of water.

Optionally, the conditions of the first catalytic conversion reaction comprise a reaction temperature of 550-750 ℃, preferably 600-750 ℃, further preferably 650-700 ℃, 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 C ₄-C₈ olefin in the olefin-rich feedstock is 50-100wt%, preferably 80-100wt%, further preferably 90-100wt%, preferably, the olefin-rich feedstock is selected from one or more of a C ₄ fraction produced by an alkane dehydrogenation device, a C ₄ fraction produced by a refinery catalytic cracking device, a C ₄ fraction produced by an ethylene plant steam cracking device, a C ₄ olefin-rich fraction produced by MTO byproduct and a C ₄ -rich olefin byproduct by-product.

Optionally, the first thermally regenerated catalyst comprises 1-50 wt% of a molecular sieve, 5-99 wt% of an inorganic oxide and 0-70 wt% of clay, wherein 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 a mesoporous ZSM-5 series molecular sieve, the inorganic oxide is selected from one or more of silica and aluminum oxide, and the clay is selected from one or more of kaolin, halloysite, montmorillonite, diatomite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite.

Optionally, the method further comprises the steps of carrying out gas-solid separation on the reacted material flow to obtain reaction oil gas containing olefin and a first spent catalyst, and then burning the first spent catalyst and returning the first spent catalyst to the first reactor.

Optionally, the method further comprises the steps of enabling heavy hydrocarbon oil to contact with a second thermal regeneration catalyst in a second reactor to carry out a second catalytic conversion reaction to obtain a light oil-containing reactant stream, setting a cooling zone at the downstream of a reaction zone when the temperature of the upper region of the light oil-containing reactant stream in the reaction zone of the second catalytic conversion reactor exceeds 530 ℃, cooling the light oil-containing reactant stream to below 530 ℃, mixing the cooled light oil-containing reactant stream with the reacted reactant stream, carrying out catalyst separation on the mixed reactant stream to obtain a mixed reactant stream and a mixed to-be-produced catalyst, carrying out first separation on the mixed reactant stream to obtain dry gas, light olefins and distillate oil with the temperature of more than ₄ ℃, carrying out second separation on the distillate oil with the temperature of more than ₄ and returning the separated olefin-rich components to the first reactor to continue the reaction, carrying out burning regeneration on the mixed to-be-produced catalyst and carrying out the regeneration on the mixed to obtain the regenerated catalyst, and carrying out the catalyst, wherein the mixed reactant stream and the mixed reactant stream are subjected to the first catalytic conversion reaction and the distillate oil-rich components with the temperature of more than ₄ ℃ and the distillate oil, and the temperature of the mixed reactant stream are preferably returned to the first reactor at the temperature of between 0 and 0 ℃ and 0.0-1, preferably between the preferred temperature and 0-1 and 0.0 MPa, and 1-1, and preferably between the preferred temperature and 0.0.0-1, and 0.0-1, and preferably between the preferred temperature.

Through the technical scheme, the invention has the following beneficial effects:

(1) According to the invention, the heat is instantly supplemented for the dense-phase fluidized bed layer, so that the raw material rich in olefin 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, the light raw material is promoted to carry out single-molecule cracking reaction, and the yield and selectivity of low-carbon olefin with high added value such as ethylene in the obtained product are improved;

(2) According to the invention, the reacted material flow is rapidly cooled in the cooling zone through the cooling medium, so that the control of the catalytic cracking reaction and the thermal cracking reaction is optimized, the deep reaction in the reaction process can be effectively inhibited, and the yield and the selectivity of the low-carbon olefin are improved.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:

FIG. 1 is a schematic diagram of one embodiment of a first reactor provided by the present invention.

Fig. 2 is a schematic view of yet another embodiment of the first reactor provided by the present invention.

FIG. 3 is a schematic diagram of one embodiment of the method provided by the present invention.

Fig. 4 is a schematic diagram of yet another embodiment of the method provided by the present invention.

Description of the reference numerals

1 Pipeline 2 first lifting section 3 regeneration inclined tube

4 Feed line 5 gas-solid mixed fluid distributor 6 line

7 Pipeline 8 feeding fluid distributor 9 heater

10 Feed line 11 first catalytic conversion reaction zone 12 line

13 Fluid distributor 14 cooling zone 15 second lifting section

16 Horizontal pipe 17 pipeline 18 pre-lifting medium

19 Feed line 20 pre-lift section 21 second catalytic conversion reaction zone

22 Stripping steam 23 stripping section 24 waiting inclined tube

25 Outlet section 26 settler 27 plenum

28 Pipeline 29 regenerator 30 regeneration inclined tube

31 Fractionation column 32 line 33 line

34 Line 35 line 36 line

37 Line 38 alkane-alkene separation plant 39 line

40 Line 41 line 42 line

Detailed Description

The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.

The inventors found that when the low-carbon olefin is prepared by catalytic cracking of an olefin-rich feedstock, a higher reaction temperature is required for the activation of the small molecules, as the reaction proceeds, the temperature of the reaction mass is gradually lower than the optimum reaction temperature, and when the temperature is lowered to a large extent, the olefin feedstock is liable to polymerize, the cracking of the light feedstock gradually tends to bimolecular cracking, resulting in a decrease in the yield of ethylene or the like, and the yield of butene and higher-carbon-atom-number olefins increases. Accordingly, the present invention has been made.

The invention provides a method for preparing low-carbon olefin, which comprises the following steps of enabling a raw material rich in olefin to be in contact with a first thermal regeneration catalyst, carrying out a first catalytic conversion reaction in a dense-phase fluidized bed layer of a first reactor provided with an instant heat supplementing system, enabling a reacted material flow to rapidly cool in a cooling zone near the upper part in the first reactor, enabling the reacted material flow to cool to a target temperature of 450-530 ℃ and then sending the material flow out of the first reactor.

According to the invention, the heat is instantly supplemented for the dense-phase fluidized bed layer, so that the raw material rich in olefin 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, the light raw material is promoted to carry out single-molecule cracking reaction, and the yield and selectivity of low-carbon olefin with high added value such as ethylene in the obtained product are improved. Meanwhile, the reacted material flow is rapidly cooled in a cooling zone through a cooling medium, so 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 yield and the selectivity of the low-carbon olefin are improved.

The instant heat supplementing system comprises a catalyst supplementing pipe for introducing additional heat into the dense-phase fluidized bed layer of the regenerated catalyst, or comprises a heater arranged in the dense-phase fluidized bed layer of the first reactor, wherein a heating medium in the heater is at least one of high-temperature steam and steam cracking gas. The heat is instantly supplied to the dense phase fluidized bed, so that the olefin molecular polymerization reaction under the low temperature condition can be obviously inhibited, the generation of macromolecular olefin products is reduced, and the selectivity and the yield of low-carbon olefin, especially ethylene products in the products are improved, thereby obtaining the target products with high quality and high selectivity.

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

Wherein the reacted stream is cooled to the cooled target temperature in 0.5-2 seconds, preferably in 0.5-1 second.

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

Fig. 1 is a schematic diagram of an embodiment of a first reactor provided by the present invention, and as shown in fig. 1, the first reactor includes a first lifting section, a diameter-expanding section, a dense-phase fluidizing section, a diameter-reducing section and a second lifting section from bottom to top. The included angle between the side wall of the expanding section and the axis is 5-60 degrees, the ratio of the diameter of the dense phase fluidization section to the height is (0.1-10): 1, and the included angle between the side wall of the reducing section and the axis is 5-60 degrees.

The tail part of the first lifting section is also provided with a gas-solid mixed fluid distributor, and the gas-solid fluid distributor comprises a transverse distribution plate with a plurality of openings and a distribution pipe connected with the openings. The side wall of the expanding section is provided with an inlet for introducing a thermal regeneration catalyst so as to supplement heat for the reaction system in time.

In the invention, the cooling zone is arranged at the tail part of the dense phase fluidization section;

Specifically, a heat collector for cooling the reacted material flow is arranged 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 annularly arranged along the circumferential direction of the first reactor.

As a preferred embodiment, the heat extractors are arranged in the circumferential direction of the cooling zone, or the heat extractors are ring-shaped. The medium in the heat collector flows to remove part of heat of the reactant flow, thereby achieving the purpose of inhibiting thermal cracking, secondary cracking and deep reaction of the reactant.

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

In particular, the second lifting section may be cylindrical, preferably with a horizontal tube connected to the end of the second lifting section for connection with a subsequent catalyst separation device. The diameter or shape of the second lifting section and the horizontal tube may be determined according to actual needs.

Wherein the conditions of the first catalytic conversion reaction comprise a reaction temperature of 550-750 ℃, preferably 600-750 ℃, further preferably 650-700 ℃, a reaction pressure of 0.1-1MPa, preferably 0.1-0.7MPa, a reaction time of 0.2-10s, preferably 0.2-0.5s, and a weight ratio of the first thermally regenerated catalyst to the olefin-rich feedstock of (1-100): 1, preferably (5-50): 1.

Preferably, the C ₄-C₈ olefin content of the olefin-rich feedstock is from 50 to 100 wt.%, preferably from 80 to 100 wt.%, further preferably from 90 to 100 wt.%.

Preferably, the olefin-rich raw material is selected from one or more of C ₄ or more fractions generated by an alkane dehydrogenation device, C ₄ or more fractions generated by a catalytic cracking device of an oil refinery, C ₄ or more fractions generated by a steam cracking device of an ethylene plant, C ₄ or more olefin-rich fractions generated by MTO (methanol to olefin) byproducts and C ₄ or more olefin-rich fractions generated by MTP (methanol to propylene) byproducts.

In a preferred embodiment of the invention, the olefin-rich feedstock can be derived from at least one of naphtha, aromatic raffinate or other light hydrocarbons, and in practice, the resulting alkane product can also be produced using different petrochemical plants.

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

Preferably, the molecular sieve is selected from one or more of ZSM-5 series molecular sieve and SAPO series molecular sieve, preferably mesoporous ZSM-5 series molecular sieve, the inorganic oxide is selected from one or more of silicon dioxide and aluminum oxide, and the clay is selected from one or more of kaolin, halloysite, montmorillonite, diatomite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite.

The method further comprises the steps of carrying out gas-solid separation on the reacted material flow to obtain reaction oil gas containing olefin and a first spent catalyst, and then, burning the first spent catalyst and returning the first spent catalyst to the first reactor.

The method further comprises the steps of enabling heavy hydrocarbon oil to be in contact with a second thermal regeneration catalyst in a second reactor to carry out second catalytic conversion reaction to obtain a light oil-containing reactant stream, when the temperature of the upper middle region of the light oil-containing reactant stream in the reaction region of the second catalytic conversion reactor exceeds 530 ℃, setting a cooling region at the downstream of the reaction region, cooling the light oil-containing reactant stream to below 530 ℃, mixing the cooled light oil-containing reactant stream with the reacted reactant stream, carrying out catalyst separation on the mixed reactant stream to obtain a mixed reactant stream and a mixed to-be-produced catalyst, carrying out first separation on the mixed reactant stream to obtain dry gas, light olefins and distillate with the temperature of more than ₄, carrying out second separation on the distillate with the temperature of more than ₄, returning the separated olefin-rich components to the first reactor to continue reaction, carrying out coke burning regeneration on the mixed to the regenerated catalyst, and carrying out thermal conversion on the mixed to the regenerated catalyst, wherein the mixed to the first reactor and the second reactor, and the temperature of the mixed reactant stream is preferably equal to or more than 3 MPa, and the temperature is preferably equal to or less than 0.0.0-1, and the preferred temperature is preferably equal to 1-1, and the preferred temperature is preferably equal to 1-1.0-1, and the preferred 1-0.0 MPa.

In the first reactor shown in fig. 1, the pre-lift medium enters the first lift section 2 through the pipeline 1, the first thermal regenerated catalyst from the regeneration inclined pipe 3 ascends under the action of the pre-lift medium, and then enters the first catalytic conversion reaction zone 11 through the distribution action of the gas-solid mixed fluid distributor 5. The raw material rich in olefin is introduced into the first reactor through a pipeline 10 at the side of the first reactor, enters the first catalytic conversion reaction zone under the action of a gas-solid mixed fluid distributor 5 and contacts with the first thermal regenerated catalyst to generate catalytic cracking reaction. Additional first thermally regenerated catalyst from the regenerator enters the first reactor from the bottom of the first catalytic conversion reaction zone via line 7 to immediately supplement the heat for the catalytic cracking reaction of the olefin-rich feedstock. The cooling medium from the other sections enters the annular flow distributor 13 via line 12 into cooling zone 14 to remove some of the heat from the reacted stream. The cooled reacted stream is accelerated by the second lifting section 15 and enters the subsequent catalyst separation system through the horizontal pipe 16.

In another embodiment, as shown in FIG. 2, the difference from FIG. 1 is that the olefin-rich feedstock is introduced via line 4 on the side of the first riser 2 and enters the first catalytic conversion reaction zone 11 under the influence of the gas-solid mixed fluid distributor 5 to contact the first thermally regenerated catalyst for catalytic cracking reaction. A heater 9 is arranged in the first catalytic conversion reaction zone 11, and a heating medium is introduced into the heater 9 through a pipeline 6 to supplement heat for the reaction system.

In another embodiment, as shown in fig. 3, the pre-lifting medium enters the first lifting section 2 through the pipeline 1, the first thermal regenerated catalyst from the regeneration inclined pipe 3 ascends 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 raw material rich in olefin is introduced into the first reactor through a pipeline 10 at the side of the first reactor, enters the first catalytic conversion reaction zone under the action of a gas-solid mixed fluid distributor 5 and contacts with the first thermal regenerated catalyst to generate catalytic cracking reaction. The heating medium from the other sections is introduced into the heater 9 through the line 6 to instantaneously supplement the heat for the reaction system to inhibit the polymerization of the olefin feedstock at low temperature, and the cooling medium from the other sections is introduced into the fluid distributor through the line 12 and into the cooling zone 14 to rapidly reduce the temperature of the reacted stream. The reactant after the cooling treatment flows through the second lifting section 25 to be accelerated and then enters the catalyst separation device. In the catalyst separation device, the reacted material flow enters a cyclone separator of a settler 26 to separate a first spent catalyst from first reaction oil gas, the first spent catalyst flows to a stripping section 23 after being settled and contacts stripping steam from a pipeline 22 to strip residual reaction oil gas on the first spent catalyst, the stripped first spent catalyst enters a regenerator 29 through a pipeline 24 to be burnt and regenerated, and the regenerated first catalyst returns to the first reactor through a pipeline 3.

The first reaction oil gas separated by the cyclone separator enters a gas collection chamber 27, then enters a fractionating tower 31 through a pipeline 28 for first separation, the separated hydrogen, methane and ethane are led out through a pipeline 32, the ethylene is led out through a pipeline 33, the propylene is led out through a pipeline 34, the butylene is led out through a pipeline 35, the propane and butane are led out through a pipeline 36, the other components enter an alkane-alkene separation device 38 through a pipeline 37 for second separation, the separated olefin-free material flow is sent to an alkane treatment device through a pipeline 39, and the olefin-containing fraction is mixed with the olefin-rich raw material from a pipeline 41 through a pipeline 40 and returned to the first reactor for continuous participation in the reaction.

In another embodiment of the invention, the catalytic cracking process of the heavy feedstock and the catalytic conversion process of the olefin-rich feedstock can also be coupled, and referring to fig. 4, the pre-lift medium is introduced into the first lift section 2 through the pipeline 1, the first thermal regenerated catalyst from the regeneration chute 3 is lifted by the pre-lift medium, and then introduced into the first catalytic conversion reaction zone 11 through the distribution of the gas-solid mixed fluid distributor 5. The raw material rich in olefin is introduced into the first reactor through a pipeline 10 at the side of the first reactor, enters the first catalytic conversion reaction zone under the action of a gas-solid mixed fluid distributor 5 and contacts with the first thermal regenerated catalyst to generate catalytic cracking reaction. The high temperature regenerated catalyst from the regenerator enters the first reactor via line 7 to immediately supplement the heat for the reaction system. The reacted stream is cooled in cooling zone 14 by cooling medium from line 12 and passed to a catalyst separation unit via a second lift section 15.

The pre-lift medium enters the first lift section 20 via line 18 and moves upwardly with the regenerated catalyst from line 30, and the heavy feedstock enters the second reactor via line 19 and contacts the second thermally regenerated catalyst to undergo catalytic conversion in the reaction zone of the second reactor, the reacted light oil-containing reactant stream being cooled at a temperature above 530 ℃ by cooling medium from line 42 and entering the catalyst separation device via outlet section 25.

In the catalyst separation device, the reacted stream from the first reactor is mixed with the light oil-containing reactant stream from the second reactor and then passed into the cyclone of the settler 26 for separation of spent catalyst from the reaction oil and gas. Spent catalyst is settled and then flows to the stripping section 23 to contact stripping steam from the pipeline 22, and then enters the regenerator 29 through the pipeline 24 for burning regeneration, and the obtained regenerated catalyst is returned to the first reactor and the second reactor through the pipeline 3 and the pipeline 30 respectively.

The separated mixed reactant stream enters a gas collection chamber 27 and is led into a fractionating tower 31 through a pipeline 28 for first separation, the separated hydrogen, methane and ethane are led out through a pipeline 32, the ethylene is led out through a pipeline 33, the propylene is led out through a pipeline 34, the butylene is led out through a pipeline 35, the propane and butane are led out through a pipeline 36, other components enter an alkane-alkene separation device 38 through a pipeline 37 for second separation, the separated olefin-free stream is sent to an alkane treatment system through a pipeline 39, and the olefin-containing fraction is mixed with the olefin-rich raw material from a pipeline 41 through a pipeline 40 and then enters the first reactor for continuous reaction.

The invention is illustrated in further detail by the following examples. The starting materials used in the examples are all available commercially. The catalyst used in the examples and comparative examples was an industrial product produced by Qilu division of China petrochemical catalyst Co., ltd, and the trade name was TCC-1. The properties of the heavy hydrocarbon oil I used are shown in Table 1.

TABLE 1

Example 1

This example was conducted in a fluidized-bed catalytic conversion reaction apparatus shown in FIG. 1, wherein 1-hexene was used as a raw material and TCC-1 was used as a catalyst. The reaction raw material 1-hexene enters a fluidized bed catalytic conversion reaction device from a side feed pipeline of a reaction zone, then enters the reaction zone through a feed fluid distributor, contacts with a TCC-1 catalyst at 650 ℃ to carry out cracking reaction, the catalyst density of the reaction zone is 400kg/m ³, and meanwhile, the bottom of the reactor is additionally fed with a thermal regenerated catalyst TCC-1 at 700 ℃. And cooling the reacted material flow by a cooling medium introduced by a cooling zone. The weight ratio of catalyst to 1-hexene was 30:1, and the operating conditions and product distribution are shown in Table 2.

Example 2

This example was conducted in a fluidized-bed catalytic conversion reaction apparatus shown in FIG. 2, wherein 1-hexene was used as a raw material and TCC-1 was used as a catalyst. The reaction raw material 1-hexene enters a fluidized bed catalytic conversion reaction device from a feed pipeline at the bottom of a reaction zone, then enters the reaction zone through an annular gas-solid mixed fluid distributor, contacts with a TCC-1 catalyst at 650 ℃ to carry out cracking reaction, the catalyst density of the reaction zone is 400kg/m ³, and heat is instantly supplemented at two sides of the reaction zone through a heater. The weight ratio of catalyst TCC-1 to 1-hexene was 30:1, and the operating conditions and product distribution are shown in Table 2.

Comparative example 1

This comparative example was conducted in a fluidized-bed catalytic conversion reaction apparatus shown in FIG. 1, in which 1-hexene was used as a raw material and TCC-1 was used as a catalyst. The reaction raw material 1-hexene enters a fluidized bed catalytic conversion reaction device from a side feed pipeline of a reaction zone, enters the reaction zone through an annular gas-solid mixed fluid distributor, contacts with a TCC-1 catalyst at 650 ℃ to carry out cracking reaction, the catalyst density of the reaction zone is 90kg/m ³, no heat supplementing and heat taking equipment is arranged, the weight ratio of the catalyst TCC-1 to the 1-hexene is 20:1, and the operating conditions and the product distribution are shown in the table 2.

TABLE 2

Example 3

This example was carried out on a fluidized catalytic conversion reaction apparatus shown in fig. 4. Wherein, 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.

Raw material 1-hexene enters a first catalytic conversion reactor from a feed pipeline at the side of a reaction zone, then enters the first catalytic conversion reaction zone through an annular gas-solid mixed fluid distributor, contacts with a TCC-1 catalyst at 650 ℃ to carry out a first catalytic conversion reaction, the catalyst density of the reaction zone is 400kg/m ³, the reaction time is 0.5s, and simultaneously, the bottom of the reactor is filled with a thermally regenerated catalyst at 700 ℃. The weight ratio of catalyst TCC-1 to raw material 1-hexene was 30:1.

The heavy oil I contacts with a TCC-1 catalyst in a reaction zone of a second catalytic conversion reactor to carry out catalytic conversion reaction to obtain a second reactant flow, wherein the reaction temperature is 550 ℃, 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.

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

Comparative example 2

This comparative example was carried out on the catalytic conversion reaction apparatus shown in fig. 4. Wherein, 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.

The difference from example 3 is that the bottom of the first catalytic conversion reactor is not injected with thermally regenerated TCC-1 catalyst and the top is not provided with a heat-extracting device. The reaction conditions and product distribution are shown in Table 3.

TABLE 3 Table 3

As shown in tables 2 and 3, the method of the invention can inhibit the polymerization reaction of olefin raw materials under the low temperature condition to a certain extent by instantly supplementing heat to the reaction zone of the fluidized bed catalytic conversion reaction device, reduce the generation of macromolecular olefin products, and improve the selectivity and yield of low-carbon olefin products, especially products with high added value such as ethylene.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.

In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition.

Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.

Claims (10)

1. A method for preparing low-carbon olefin, which is characterized by comprising the following steps:

The method comprises the steps of enabling a raw material rich in olefin to be in contact with a first thermal regeneration catalyst, carrying out a first catalytic conversion reaction in a dense-phase fluidized bed layer of a first reactor provided with an instant heat supplementing system, enabling a reacted material flow to quickly cool in a cooling zone close to the upper part in the first reactor, enabling the reacted material flow to cool to a target temperature of 450-530 ℃ and then sending the material flow out of the first reactor.

2. The method of claim 1, wherein the instant heat make-up system comprises a catalyst make-up tube for introducing additional hot regenerated catalyst to the dense-phase fluidized bed, or comprises a heater disposed in the dense-phase 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 process 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. A process according to claim 1, wherein the reacted stream is cooled down to the target temperature of the reacted stream within 0.5-2 seconds, preferably within 0.5-1 seconds.

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

6. The method of claim 1, wherein the first reactor comprises a first lifting section, an expanding section, a dense-phase fluidizing section, a reducing section and a second lifting section from bottom to top, wherein an included angle between the side wall of the expanding section and an axis is 5-60 degrees, a ratio of the diameter of the dense-phase fluidizing section to the height is (0.1-10): 1, and an included angle between the side wall of the reducing section and the axis is 5-60 degrees;

the head of the first lifting section is provided with a first thermal regenerated catalyst inlet and a lifting medium inlet;

the middle part of the first lifting section is provided with a raw material inlet;

the tail part of the first lifting section is also provided with a gas-solid mixed fluid distributor;

the cooling area is arranged at the tail part 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 annularly arranged along the circumferential direction of the first reactor;

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

7. The process according to claim 1, wherein the conditions of the first catalytic conversion reaction comprise a reaction temperature of 550-750 ℃, preferably 600-750 ℃, further preferably 650-700 ℃, 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 C ₄-C₈ olefin content of the olefin-rich feedstock is from 50 to 100wt%, preferably from 80 to 100wt%, further preferably from 90 to 100wt%;

Preferably, the olefin-rich feedstock is selected from one or more of a C ₄ or more fraction produced by an alkane dehydrogenation device, a C ₄ or more fraction produced by a catalytic cracking device of an oil refinery, a C ₄ or more fraction produced by a steam cracking device of an ethylene plant, an olefin-rich fraction of C ₄ or more by-product MTO, and an olefin-rich fraction of C ₄ or more by-product MTP.

8. The process of claim 1, wherein the first thermally regenerated catalyst comprises 1-50 wt.% molecular sieve, 5-99 wt.% inorganic oxide, and 0-70 wt.% clay, based on the total weight of the first thermally regenerated catalyst;

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 mesoporous ZSM-5 series molecular sieves;

the inorganic oxide is selected from one or more of silicon dioxide and aluminum oxide, and the clay is selected from one or more of kaolin, halloysite, montmorillonite, kieselguhr, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite.

9. The process of claim 1, further comprising the step of subjecting the reacted stream to a gas-solid separation to obtain a reaction oil gas containing olefins and a first spent catalyst, and then returning the first spent catalyst to the first reactor after being burned.

10. The method of claim 1, wherein the method further comprises the steps of:

Contacting heavy hydrocarbon oil with a second thermal regeneration catalyst in a second reactor to perform a second catalytic conversion reaction to obtain a light oil-containing reactant stream, and when the temperature of the upper region of the light oil-containing reactant stream in the reaction region of the second catalytic conversion reactor exceeds 530 ℃, setting a cooling region at the downstream of the reaction region, and cooling the light oil-containing reactant stream to below 530 ℃;

Mixing the cooled reactant flow containing the light oil with the reacted flow, and carrying out catalyst separation on the mixed flow to obtain a mixed reactant flow and a mixed spent catalyst;

Performing a first separation on the mixed reactant stream to obtain dry gas, low-carbon olefin and distillate with more than C ₄, performing a second separation on the distillate with more than C ₄ and returning the separated components rich in olefin to the first reactor for continuous reaction, and

Carrying out burning 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 a reaction temperature of 500-600 ℃, preferably 530-580 ℃, a reaction pressure of 0.01-1MPa, preferably 0.05-1MPa, a reaction time of 0.01-80s, preferably 0.1-60s, and a weight ratio of the second thermally regenerated catalyst to the heavy hydrocarbon oil of (1-100): 1, preferably (3-50): 1.