Downflow bed reaction system and method for producing lower carbon olefins and aromatic hydrocarbons

Abstract

The present disclosure relates to a down-flow bed reaction system and method for producing low-carbon olefins and aromatic hydrocarbons by catalytic conversion of light hydrocarbon oil, which adopts a down-flow bed reactor in a counter-gravity field, can reduce gas-solid axial backmixing, provide a near plug flow flow environment for catalytic cracking of light hydrocarbon oil, and can improve the yield of low-carbon olefins and low-carbon aromatic hydrocarbons. The device for cracking reaction and the device for catalyst regeneration are independently arranged, which can improve the adaptability and safety of the system. A full-closed anti-coking cyclone assembly or a coarse-cyclone top-cyclone closed direct connection assembly is arranged in the reaction settler, which can reduce the risk of coking of high-temperature oil gas in the reaction settler, and can reduce the risk of secondary cracking, thereby improving the yield of the target product. In addition, an oil gas quencher is arranged in the system of the present disclosure, which can avoid the safety hazards caused by excessive thermal cracking and condensation coking of reaction oil gas in the reactor outlet large oil gas pipeline, and can effectively utilize the heat in the high-temperature reaction oil gas.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of petroleum chemical industry, in particular, to a down-flow bed reaction system and method for producing low-carbon olefins and aromatic hydrocarbons. BACKGROUND

[0002] Low-carbon olefins (ethylene, propylene) and low-carbon aromatic hydrocarbons (BTX) are important basic organic raw materials for petroleum chemical industry, and play an important role in the petrochemical industry.

[0003] Ethylene is a basic chemical raw material for synthetic fibers, synthetic rubber, synthetic plastics (polyethylene and polyvinyl chloride), and synthetic ethanol (alcohol), and is also used to manufacture vinyl chloride, styrene, ethylene oxide, acetic acid, acetaldehyde, and explosives. Propylene, as an important basic raw material for petroleum chemical industry next to ethylene, is widely used to produce polypropylene, acrylonitrile, isopropanol, phenol and acetone, butanol and octanol, acrylic acid and its esters, and to synthesize epoxypropane and propylene glycol, epichlorohydrin, and glycerol. Aromatic hydrocarbons are an important organic chemical basic raw material, among which benzene, toluene and xylene (including o-xylene, m-xylene and p-xylene) are widely used, and their end products are used in the fields of synthetic resins, synthetic fibers, synthetic rubber, coatings, dyes and pharmaceuticals.

[0004] In recent years, other new technologies for producing low-carbon olefins and low-carbon aromatic hydrocarbons have received more and more attention, and the technology for producing low-carbon olefins and low-carbon aromatic hydrocarbons by catalytic cracking is one of the most widely used technologies. For example, the prior art proposes a method for converting petroleum hydrocarbon raw materials into low-carbon olefins through a catalytic cracking (cracking) reaction process, but still fails to solve the problems of insufficient heat in the reaction-regeneration system, safety hazards caused by reactor wear, and high-temperature crushing and deactivation of the catalyst during the catalytic conversion of light hydrocarbon oil, and does not involve a scheme for recovering high-value low-carbon aromatic hydrocarbons and improving the yield of low-carbon aromatic hydrocarbons. SUMMARY

[0005] The purpose of the present disclosure is to provide a down-flow bed reaction system and method for producing low-carbon olefins and aromatic hydrocarbons to solve the problems of insufficient heat in the reaction-regeneration system, safety hazards caused by reactor wear, and high-temperature crushing and deactivation of the catalyst in the prior art.

[0006] To achieve the above object, the first aspect of the present disclosure provides a down-flow bed reaction system for producing low-carbon olefins and aromatic hydrocarbons, which comprises a down-flow bed reactor, a reaction product purification separation unit, an oil gas quenching device and a regenerator; the reaction product purification separation unit and the oil gas quenching device are coaxially arranged, and the oil gas quenching device is arranged at the top of the reaction product purification separation unit; the reaction product purification separation unit comprises a stripping section and a reaction settler from bottom to top, and the stripping section and the reaction settler are separated by a sealing cover plate; the down-flow bed reactor and the reaction product purification separation unit are arranged side by side; a fully-closed anti-coking cyclone assembly is arranged in the reaction settler; the fully-closed anti-coking cyclone assembly comprises a cyclone quick separation head, a closed cover and a reaction cyclone separator; the closed cover is a sealing cylinder arranged at the upper part of the reaction settler; the outlet at the upper part of the sealing cylinder is communicated with the inlet of the reaction cyclone separator through a flow guide cylinder; the lower part of the sealing cylinder extends downward into the stripping section through the sealing cover plate, and the lower part of the closed cover is provided with a notch so that the inside and outside of the closed cover are communicated only through the notch; the bottom of the down-flow bed reactor is embedded in the inside of the reaction product purification separation unit, and the bottom of the down-flow bed reactor extends into the sealing cylinder, and the cyclone quick separation head is arranged at the bottom outlet of the down-flow bed reactor; alternatively, a coarse-rotation top-rotation closed direct-connection assembly is arranged in the reaction settler; the coarse-rotation top-rotation closed direct-connection assembly comprises a coarse-rotation device, an oil gas collecting pipe, an oil gas closed guide pipe and a reaction cyclone separator; the bottom outlet of the down-flow bed reactor is communicated with the inside of the oil gas collecting pipe through the coarse-rotation device; the gas outlet of the oil gas collecting pipe is communicated with the inlet of the reaction cyclone separator; the bottom inlet of the oil gas closed guide pipe extends downward into the upper gas phase space of the stripping section through the sealing cover plate; the gas phase space at the lower part of the sealing cover plate is communicated with the oil gas collecting pipe through the oil gas closed guide pipe and the oil gas collecting pipe; the regenerator comprises a spent catalyst inlet and a regenerated catalyst outlet; the stripping section comprises a spent catalyst outlet, and the down-flow bed reactor comprises a regenerated catalyst inlet; the spent catalyst outlet of the stripping section is communicated with the spent catalyst inlet of the regenerator through a spent catalyst inclined pipe; the regenerated catalyst inlet of the down-flow bed reactor is communicated with the regenerated catalyst outlet of the regenerator through a regenerated catalyst inclined pipe.

[0007] Optionally, the down-flow bed reaction system further comprises an equal-diameter cylindrical riser; the lower part of the riser is provided with a regenerated catalyst inlet for being communicated with the outlet of the regenerated catalyst inclined pipe; the top outlet of the riser is communicated with the top inlet of the down-flow bed reactor; alternatively, the lower part of the riser is provided with a spent catalyst inlet, and the upper part of the riser is provided with a spent catalyst outlet; the spent catalyst inlet of the riser is communicated with the outlet of the spent catalyst inclined pipe, and the spent catalyst outlet of the riser is communicated with the spent catalyst inlet of the regenerator.

[0008] Optionally, the reaction settler is further provided with a reaction gas collection chamber; the outlet of the reaction gas collection chamber is communicated with the top outlet of the reaction settler; the reaction cyclone separator is two stages or more than two stages; the outlet of the draft tube is communicated with the inlet of the first stage reaction cyclone separator; the gas outlet of the last stage reaction cyclone separator is communicated with the inlet of the reaction gas collection chamber; the catalyst outlet of the reaction cyclone separator extends downward through the seal cover plate to the gas phase space formed by the outer wall of the closed cover and the seal cover plate by a leg; or, the gas outlet of the oil gas collection pipe is communicated with the inlet of the first stage reaction cyclone separator; the gas outlet of the last stage reaction cyclone separator is communicated with the inlet of the reaction gas collection chamber; the catalyst outlet of the coarse cyclone and the catalyst outlet of the reaction cyclone separator extend downward through the seal cover plate to the gas phase space by a leg.

[0009] Optionally, the stripping section comprises stripping section internals, at least one set of stripping steam rings and loosening steam rings; the stripping section internals comprise one or more of herringbone baffle, annular baffle, disc umbrella baffle, packing and grid; the stripping steam rings are located in the middle and / or lower part of the stripping section and are used for being communicated with a stripping steam source; the loosening steam rings are located in the bottom of the stripping section and are used for being communicated with a loosening steam source; the upper surface and / or lower surface of the stripping steam rings and the loosening steam rings are provided with steam wear-resistant nozzles.

[0010] Optionally, the oil gas quencher comprises an oil gas distributor, a quencher baffle, a quenching medium distributor and a stirring steam ring; the oil gas distributor is located at the bottom of the oil gas quencher and the top outlet of the reaction settler is communicated with the inlet of the oil gas distributor; the quencher baffle is located above the oil gas distributor; the quencher baffle has 1-20 layers; the quenching medium distributor is located above the quencher baffle; the lower surface of the quenching medium distributor is provided with injection holes, the airflow direction of the injection holes of the quenching medium distributor is vertical downward and / or oblique downward; the stirring steam ring is located in the lower part of the oil gas quencher; the upper surface of the stirring steam ring is provided with injection holes, the airflow direction of the injection holes of the stirring steam ring is vertical upward and / or oblique upward.

[0011] The second aspect of the present disclosure adopts the down-flow bed reaction system of the first aspect of the present disclosure to produce low-carbon olefins and aromatics from catalytic conversion of light hydrocarbon oil. The method comprises: feeding the light hydrocarbon oil feedstock into the down-flow bed reactor to contact with the regenerated catalyst for cracking reaction to obtain a reaction material containing cracking reaction products and spent catalyst; feeding the reaction material through the outlet of the down-flow bed reactor into the full-closed anti-coking cyclone assembly or the coarse-rotation top-rotation closed direct connection assembly in the reaction settler for separation and treatment to obtain high-temperature reaction oil gas and spent catalyst material; feeding the spent catalyst material into the stripping section for stripping treatment to obtain spent catalyst; feeding the spent catalyst through the spent catalyst inclined pipe into the regenerator for regeneration treatment to obtain regenerated catalyst; feeding the regenerated catalyst back to the down-flow bed reactor through the regenerated catalyst inclined pipe; feeding the high-temperature reaction oil gas into the oil gas quencher to exchange heat with the quenching medium to obtain low-temperature reaction oil gas; and further separating the low-temperature reaction oil to obtain low-carbon olefins and low-carbon aromatics.

[0012] Optionally, the light hydrocarbon oil feedstock is selected from one or more of light distillate with a distillation range of 20-300°C, preferably catalytic cracking gasoline, catalytic cracking gasoline, straight-run naphtha, coking naphtha, thermal cracking naphtha, thermal cracking naphtha, hydrogenated naphtha, reforming raffinate, straight-run kerosene, and hydrogenated kerosene; the regenerated catalyst comprises zeolite, inorganic oxide, and clay; the content of zeolite is 0.5-90% by weight, the content of inorganic oxide is 1-99% by weight, and the content of clay is 0-80% by weight, based on the total weight of the regenerated catalyst; the zeolite comprises mesoporous zeolite, medium-pore zeolite, and optional macroporous zeolite; the content of mesoporous zeolite is 10-90% by weight, the content of medium-pore zeolite is 10-90% by weight, and the content of macroporous zeolite is 0-50% by weight, based on the total weight of the zeolite; and the quenching medium is selected from heavy oil products with an initial boiling point of above 300°C, preferably one or more of cracking heavy oil, catalytic cracking slurry, catalytic cracking slurry, coking slurry, atmospheric residue, and vacuum residue.

[0013] Optionally, the reaction conditions of the cracking reaction include: preheating temperature of 40-600°C, reaction temperature of 400-900°C, reaction pressure of 0.01-1.0 MPa(g), reaction time of 0.1-30 s, mass flow rate ratio of the regenerated catalyst to the light hydrocarbon oil feedstock of 1-100, and mass flow rate ratio of water vapor to the light hydrocarbon oil feedstock of 0.05-2; the operating conditions of the stripping section include: average gas superficial linear velocity of 0.05-1 m / s and average catalyst residence time of 0.5-10 min; and the operating conditions of the oil gas quencher include: outlet reaction oil gas temperature of 200-550°C, bottom liquid temperature of 200-500°C, and bottom liquid residence time of 0-15 min.

[0014] Optionally, the regenerated catalyst is made to pass through the regeneration inclined pipe into the lower part of the riser pipe and enter the downer reactor under the action of the lifting medium to contact with the light hydrocarbon oil feedstock to perform the cracking reaction; or the spent catalyst is made to pass through the spent inclined pipe into the lower part of the riser pipe and enter the regenerator to perform the regeneration treatment under the action of the lifting medium.

[0015] Optionally, the method further comprises making the reaction material pass through the cyclone quick separation head at the outlet of the downer reactor to perform first separation to obtain a coarse separation oil gas and first spent catalyst; making the first spent catalyst flow downward in the internal space of the closed cover and flow into the stripping section; making the coarse separation oil gas flow upward along the internal space of the closed cover and pass through the flow guide cylinder to enter the reaction cyclone separator to perform separation to obtain the high-temperature reaction oil gas and the second spent catalyst; making the high-temperature reaction oil gas enter the oil gas quenching device from the gas phase outlet of the reaction cyclone separator; and making the second spent catalyst of the reaction cyclone separator flow into the gas phase space formed by the outer wall of the closed cover and the sealing cover plate and finally enter the stripping section through the slot.

[0016] By the above technical solution, the downer reactor in the order of gravity field is adopted, the gas-solid transfer characteristics are good, the gas-solid axial back mixing can be reduced, a near plug flow flow environment is provided for the catalytic cracking of light hydrocarbon oil, the yield of low-carbon olefins and low-carbon aromatic hydrocarbons can be improved, the device for cracking reaction and the device for catalyst regeneration are independently arranged, the adaptability and safety of the system can be improved, the full-closed anti-coking cyclone assembly or the coarse-rotation top-rotation closed direct-connection assembly is arranged in the reaction settler, the risk of coking of high-temperature oil gas in the reaction settler can be reduced, the risk of secondary cracking can be reduced, and the yield of the target product can be improved. In addition, the oil gas quenching device is arranged in the system of the present application, the temperature of the reaction oil gas at the outlet of the reactor can be quickly reduced, the safety hidden danger caused by excessive thermal cracking and condensation coking of the reaction oil gas in the large oil gas pipeline at the outlet of the reactor can be avoided, and the heat in the high-temperature reaction oil gas can be effectively utilized.

[0017] Other features and advantages of the present disclosure will be described in detail in the following detailed description section. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and serve to explain the principles of the present disclosure, but are not intended to limit the present disclosure. In the drawings:

[0019] Figure 1 is a schematic diagram of a downflow bed reaction system for producing low carbon olefins and aromatic hydrocarbons in Embodiment 1 of the present disclosure.

[0020] Figure 2 is a schematic diagram of a downflow bed reaction system for producing low carbon olefins and aromatic hydrocarbons in Embodiment 2 of the present disclosure.

[0021] Figure 3 is a schematic diagram of a downflow bed reaction system for producing low carbon olefins and aromatic hydrocarbons in Embodiment 3 of the present disclosure.

[0022] Figure 4 is a schematic diagram of a downflow bed reaction system for producing low carbon olefins and aromatic hydrocarbons in Embodiment 4 of the present disclosure.

[0023] BRIEF DESCRIPTION OF DRAWINGS

[0024] 1, riser; 2, downflow bed reactor; 3, stripping section; 4, reaction settler; 5, oil gas quencher; 6, regenerator; 11, regenerated inclined pipe; 12, regenerated slide valve; 13, spent inclined pipe; 14, spent slide valve; 15, main air distributor; 16, regenerated cyclone separator; 17, regenerated plenum; 18, stripping steam ring; 19, loosening steam ring; 21, cyclone quick separation head; 22, closure cover; 23, sealing cover plate; 24, slot; 25, reaction cyclone separator; 26, anti-coking steam ring; 27, reaction plenum; 28, oil gas distributor; 29, quencher baffle; 30, quenching medium distributor; 31, stirring steam ring; 100, pre-lifting medium; 101, back-mixing medium; 102, light hydrocarbon oil feedstock; 103, dilution steam; 104, loosening steam; 105, stripping steam; 106, anti-coking steam; 107, heat-exchanged quencher medium; 108, stirring steam; 109, quenching medium; 110, temperature-reduced reaction oil gas; 121, coarse cyclone; 122, oil gas collecting pipe; 124, oil gas closed guide pipe. DETAILED DESCRIPTION

[0025] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present disclosure, and are not intended to limit the present disclosure.

[0026] The first aspect of the present disclosure provides a down-flow bed reaction system for producing low-carbon olefins and aromatic hydrocarbons, which comprises a down-flow bed reactor 2, a reaction product purification separation unit, an oil gas quenching device 5 and a regenerator 6; the reaction product purification separation unit and the oil gas quenching device 5 are coaxially arranged, and the oil gas quenching device 5 is arranged at the top of the reaction product purification separation unit; the reaction product purification separation unit comprises a stripping section 3 and a reaction settler 4 from bottom to top, and the stripping section 3 and the reaction settler 4 are separated by a sealing cover plate 23; the down-flow bed reactor 2 and the reaction product purification separation unit are arranged side by side.

[0027] The reaction settler 4 is provided with a fully-closed anti-coking cyclone assembly; the fully-closed anti-coking cyclone assembly comprises a cyclone quick separation head 21, a closed cover 22 and a reaction cyclone separator 25; the closed cover 22 is a sealing cylinder arranged at the upper part of the reaction settler 4; the outlet at the upper part of the sealing cylinder is communicated with the inlet of the reaction cyclone separator 25 through a flow guide cylinder, so that the reaction product can be separated into spent catalyst and reaction oil gas through the reaction cyclone separator 25; the lower part of the sealing cylinder extends downward into the stripping section 3 through the sealing cover plate 23, and the lower part of the closed cover 22 is provided with a notch 24, so that the inner side and the outer side of the closed cover 22 are only communicated through the notch 24, so that the spent catalyst can enter the stripping section 3 from the notch 24; the bottom of the down-flow bed reactor 2 is embedded inside the reaction product purification separation unit, and the bottom of the down-flow bed reactor 2 extends into the sealing cylinder, and the cyclone quick separation head 21 is arranged at the bottom outlet of the down-flow bed reactor 2; or,

[0028] The reaction settler 4 is provided with a coarse cyclone top cyclone sealing direct connection assembly; the coarse cyclone top cyclone sealing direct connection assembly comprises a coarse cyclone 121, an oil gas collecting pipe 122, an oil gas sealing guide pipe 124 and a reaction cyclone separator 25; the bottom outlet of the down-flow bed reactor 2 is communicated with the inside of the oil gas collecting pipe 122 through the coarse cyclone 121, so that the reaction product can enter the coarse cyclone 121 for first separation; the gas outlet of the oil gas collecting pipe 122 is communicated with the inlet of the reaction cyclone separator 25, so that the reaction oil gas can be subjected to second separation; the bottom inlet of the oil gas sealing guide pipe 124 extends downward to the upper gas phase space of the stripping section 3 through the sealing cover plate 23; the gas phase space at the lower part of the sealing cover plate 23 is communicated with the oil gas collecting pipe 122 through the oil gas sealing guide pipe 124 and the oil gas collecting pipe 122; so that the spent catalyst separated by the coarse cyclone 121 and the reaction cyclone separator 25 can enter the stripping section 3 through the legs of the coarse cyclone 121 and the reaction cyclone separator 25, and the oil gas stripped out of the stripping section 3 and the oil gas carried by the catalyst discharged from the legs of the coarse cyclone 121 and the reaction cyclone separator 25 can enter the oil gas collecting pipe 122 through the oil gas sealing guide pipe 124.

[0029] The regenerator 6 comprises a spent catalyst inlet and a regenerated catalyst outlet; the stripping section 3 comprises a spent catalyst outlet, and the down-flow bed reactor 2 comprises a regenerated catalyst inlet; the spent catalyst outlet of the stripping section 3 is communicated with the spent catalyst inlet of the regenerator 6 through a spent catalyst inclined pipe 13, so that the spent catalyst of the stripping section 3 can enter the regenerator 6 through the spent catalyst inclined pipe 13 for regeneration treatment; the regenerated catalyst inlet of the down-flow bed reactor 2 is communicated with the regenerated catalyst outlet of the regenerator 6 through a regenerated catalyst inclined pipe 11, so that the regenerated catalyst can enter the down-flow bed reactor 2 through the regenerated catalyst inclined pipe 11 to participate in the reaction.

[0030] Wherein, a spent catalyst slide valve 14 is further arranged on the spent catalyst inclined pipe 13, for flexibly controlling the feed amount of the spent catalyst into the regenerator 6; a regenerated catalyst slide valve 12 is further arranged on the regenerated catalyst inclined pipe 11, for flexibly controlling the feed amount of the regenerated catalyst into the riser 1.

[0031] Through the above technical solution, the down-flow bed reactor 2 in the gravitational field is adopted, the gas-solid transfer characteristics are good, the gas-solid axial back mixing can be reduced, a near plug flow flow environment can be provided for the catalytic cracking of light hydrocarbon oil, and the yield of low-carbon olefins and low-carbon aromatic hydrocarbons can be improved. The device for cracking reaction and the device for catalyst regeneration are independently arranged, which can improve the adaptability and safety of the system. The full-closed anti-coking cyclone assembly or the coarse-rotation top-rotation closed direct connection assembly is arranged in the reaction settler 4, which can reduce the risk of coking of high-temperature oil gas in the reaction settler 4, and can reduce the risk of secondary cracking, thereby improving the yield of the target product. In addition, the oil gas quencher 5 is arranged in the system of the present application, which can quickly reduce the temperature of the reaction oil gas, avoid the safety hidden danger caused by excessive thermal cracking and coking of the reaction oil gas in the pipeline, and effectively utilize the heat in the high-temperature reaction oil gas.

[0032] As shown in Figure 1 The down-flow bed reaction system further comprises an equal-diameter cylindrical riser 1; wherein the riser 1 can be combined with the down-flow bed reactor 2, specifically, the lower part of the riser 1 is provided with a regenerated catalyst inlet for communicating with the outlet of the regenerated catalyst inclined pipe 11, and the top outlet of the riser 1 is communicated with the top inlet of the down-flow bed reactor 2, so that the regenerated catalyst transported by the regenerated catalyst inclined pipe 11 can enter the down-flow bed reactor 2 through the riser 1.

[0033] Wherein, a lifting medium nozzle is arranged at the bottom of the riser 1, and the lifting medium nozzle is communicated with a pre-lifting medium source, so that the regenerated catalyst entering the lower part of the riser 1 can enter the down-flow bed reactor 2 with the pre-lifting medium 100 to participate in the reaction.

[0034] Wherein, the back mixing medium nozzle is arranged in the middle part of the riser 1, and the back mixing medium nozzle is communicated with the back mixing medium source, so that the back mixing medium 101 entering the middle part of the riser 1 can be recycled with the lifting medium entering the down-flow bed reactor 2.

[0035] Wherein, the light hydrocarbon oil raw material nozzle is arranged at the top of the down-flow bed reactor 2, and the light hydrocarbon oil raw material nozzle is communicated with the light hydrocarbon oil raw material source to introduce the reaction raw material.

[0036] Wherein, the dilution steam nozzle is arranged in the middle part of the down-flow bed reactor 2, and the dilution steam nozzle is communicated with the dilution steam source to dilute the reaction material and improve the reaction performance.

[0037] As shown in Figure 3 The lower part of the riser 1 is provided with a spent catalyst inlet, and the upper part is provided with a spent catalyst outlet; the spent catalyst inlet of the riser 1 is communicated with the outlet of the spent catalyst inclined pipe 13, and the spent catalyst outlet of the riser 1 is communicated with the spent catalyst inlet of the regenerator 6, so that the spent catalyst first enters the riser 1 through the spent catalyst inclined pipe 13, and then enters the regenerator 6 under the action of the lifting medium for regeneration treatment.

[0038] Wherein, the lifting medium nozzle is arranged at the bottom of the riser 1, and the light hydrocarbon oil raw material nozzle, the dilution steam nozzle and the back mixing medium nozzle are arranged in the down-flow bed reactor 2 from top to bottom.

[0039] As shown in Figure 1 The reaction settler 4 is also provided with a reaction gas collecting chamber 27; the outlet of the reaction gas collecting chamber 27 is communicated with the top outlet of the reaction settler 4, and is used to send the high-temperature oil gas entering the reaction gas collecting chamber 27 into the reaction quencher for cooling.

[0040] As shown in Figure 1 The closed cover 22 in the full-closed anti-coking cyclone assembly used by the present disclosure is a cylinder with a closed top, wherein the cylinder of the closed cover 22 includes a lower end cylinder, a variable diameter section cylinder and a top cylinder which are communicated in sequence from bottom to top.

[0041] The reaction cyclone separator 25 is two or more stages, the outlet of the guide cylinder is in communication with the inlet of the first stage reaction cyclone separator, so that the oil gas material in the reaction product from the down-flow bed reactor 2 can enter the reaction cyclone separator 25 for separation, and high-temperature reaction oil gas and spent catalyst material are obtained; the gas outlet of the last stage reaction cyclone separator is in communication with the inlet of the reaction gas collecting chamber 27, so that the reaction oil gas can enter the reaction gas collecting chamber 27 for use; the catalyst outlet of the reaction cyclone separator 25 extends downward through the sealing cover plate 23 to the gas phase space formed by the outer wall of the closed cover 22 and the sealing cover plate 23, so that the catalyst can enter the stripping section 3 through the slot 24 at the bottom of the closed cover 22.

[0042] As shown in FIG. 1, the down-flow bed reactor 2 is in communication with the stripping section 3 through the full-closed anti-coking cyclone assembly or the rough cyclone top cyclone closed direct connection assembly. Figure 3

[0043] The reaction cyclone separator 25 is two or more stages, the gas outlet of the oil gas collecting pipe 122 is in communication with the inlet of the first stage reaction cyclone separator; the gas outlet of the last stage reaction cyclone separator is in communication with the inlet of the reaction gas collecting chamber 27, so that the oil gas material in the reaction product from the down-flow bed reactor 2 can enter the reaction cyclone separator 25 for separation, and high-temperature reaction oil gas and spent catalyst material are obtained, and the reaction oil gas can enter the reaction gas collecting chamber 27 for use; the catalyst outlet of the rough cyclone 121 and the catalyst outlet of the reaction cyclone separator 25 extend downward through the sealing cover plate 23 to the upper gas phase space of the stripping section 3, so that the catalyst can enter the stripping section 3.

[0044] In the above embodiment, the full-closed anti-coking cyclone assembly or the rough cyclone top cyclone closed direct connection assembly is arranged at the outlet of the down-flow bed reactor 2, so that the reaction product obtained by the reaction of the down-flow bed reactor 2 can directly enter the reaction cyclone separator 25 for separation under the action of the closed cover 22 or the oil gas collecting pipe 122, on the one hand, the residence time of the reaction product in the reaction settler 4 with large volume can be avoided, and the secondary cracking reaction can be avoided, thereby the yield of low-carbon olefin and / or low-carbon aromatic hydrocarbon product can be improved; on the other hand, the reaction product can be avoided from coking in the reaction settler 4, and the phenomenon that the device has poor anti-fluctuation can be avoided. In order to further prevent the coking phenomenon in the reaction settler 4, the rough cyclone 121 and the oil gas collecting pipe 122 in the full-closed anti-coking cyclone assembly or the rough cyclone top cyclone closed direct connection assembly are in closed communication with the outlet of the down-flow bed reactor 2. Figure 1 ​As shown, the anti-coking steam ring 26 is arranged below the reaction plenum 27 and above the closure hood 22 or the oil-gas header 122; the inlet of the anti-coking steam ring 26 is used to communicate with the anti-coking steam source; the lower surface and / or the upper surface of the anti-coking steam ring 26 can be provided with steam wear-resistant nozzles to enable the anti-coking steam 106 to pass through the anti-coking steam ring 26 and spray steam through the steam wear-resistant nozzles.

[0045] The material and arrangement position of the sealing cover plate 23 used in the present disclosure are conventional choices in the art, which only need to provide holes at different positions according to the components used in the reaction settler 4, for example, when the full-closed anti-coking cyclone component is used in the reaction settler 4, the sealing cover plate 23 is tightly combined with the outer wall of the closure hood 22, the inner wall of the reaction settler 4, and the leg outer wall of the reaction cyclone separator 25, or a gap is left therebetween; when the coarse-rotation top-rotation sealing direct-connection component is used in the reaction settler 4, the sealing cover plate 23 is tightly combined with the outer wall of the downflow bed reactor 2, the inner wall of the reaction settler 4, the leg outer wall of the coarse-rotation 121, the leg outer wall of the reaction cyclone separator 25, and the outer wall of the oil-gas sealing guide pipe 124, or a gap is left therebetween. In addition, the sealing cover plate 23 can be uniformly provided with a plurality of circular holes to enable the fluid communication between the stripping section 3 and the reaction settler 4, wherein the diameter of the circular hole is 1-100 mm.

[0046] The stripping section 3 includes the stripping section inner member 18, at least one set of stripping steam ring 19 and loosening steam ring 20; the stripping section inner member 18 includes one or more of the herringbone baffle, the ring baffle, the disc umbrella baffle, the packing, and the grid; the stripping steam ring 19 is located in the middle and / or the lower part of the stripping section 3 and is used to communicate with the stripping steam source; the loosening steam ring 20 is located at the bottom of the stripping section 3 and is used to communicate with the loosening steam source; the upper surface and / or the lower surface of the stripping steam ring 19 and the loosening steam ring 20 are provided with steam wear-resistant nozzles.

[0047] The oil gas quencher 5 comprises an oil gas distributor 28, a quencher baffle 29, a quenching medium distributor 30 and a stirring steam ring 31. The oil gas distributor 28 is located at the bottom of the oil gas quencher 5, and the top outlet of the reaction settler 4 is communicated with the inlet of the oil gas distributor 28 to enable the reaction oil gas to enter the oil gas distributor 28 for distribution. The quencher baffle 29 is located above the oil gas distributor 28. The quencher baffle 29 has 1-20 layers, preferably 3-10 layers, and more preferably 4-8 layers. The quenching medium distributor 30 is located at the upper part of the quencher baffle 29. The lower surface of the quenching medium distributor 30 is provided with a plurality of injection holes, and the airflow direction of the injection holes of the quenching medium distributor 30 is vertically downward and / or obliquely downward. The stirring steam ring 31 is located at the lower part of the oil gas quencher 5. The upper surface of the stirring steam ring 31 is provided with a plurality of injection holes, and the airflow direction of the injection holes of the stirring steam ring 31 is vertically upward and / or obliquely upward.

[0048] In this embodiment, the quenching medium 109 is heavy oil with an initial boiling point > 300℃, including but not limited to one or more combinations of self-produced cracking heavy oil, catalytic cracking slurry oil, catalytic cracking slurry oil, coking slurry oil, atmospheric residue, vacuum residue. The use of heavy oil can control the liquid temperature at the bottom of the oil gas quencher 5 to be above 300℃, and this part of high-temperature liquid can be used to heat light and heavy hydrocarbon oil feedstock or generate steam, better utilize the high-temperature heat in the high-temperature reaction oil gas, and reduce the energy consumption of the device. The oil gas quencher 5 is directly arranged above the reaction settler 4 and integrated with the reaction settler 4, or the oil gas quencher 5 is separately arranged near the reaction settler 4, so that the reaction oil gas can be cooled down in the shortest possible time to avoid coking of high-temperature oil gas. Due to the fact that the catalytic cracking gas yield of light hydrocarbon oil is much higher than that of conventional catalytic cracking, the total amount of catalyst fines entrained by the reaction oil gas is relatively large, and the slurry oil yield is much lower than that of conventional catalytic cracking, which will lead to a high solid content in the slurry oil. In order to reduce the catalyst content in the quenching medium 109, reduce the wear of equipment and pipelines, and ensure the long-term safe and stable operation of the device, the heat-exchanged quenching medium 107 is cooled by heat exchange and all or part of it enters the catalyst removal system to reduce the solid content and then circulates back to the oil gas quencher 5. The catalyst removal system includes but is not limited to one or more combinations of filters, cyclones, centrifugal separators and electric filters.

[0049] As Figure 1The regenerator 6 used in the present disclosure is a conventional selection in the art, and the present application does not make special requirements. For example, the regenerator 6 used in the present application includes a main air distributor 15 arranged at the bottom thereof, which is used to introduce main air to enable the spent catalyst to be incinerated in the presence of the main air; at least two stages of regeneration cyclone separators 16 arranged at the upper portion thereof, which are used to separate flue gas and part of the catalyst mixed in the flue gas; and a regeneration gas collecting chamber 17, which is in communication with the outlets of the regeneration cyclone separators 16, so that the flue gas after the removal of impurities is stored in the regeneration gas collecting chamber 17 or discharged from the device through the regeneration gas collecting chamber 17.

[0050] The structure type of the main air distributor 15 includes, but is not limited to, one or more combinations of a dendritic distribution pipe, a distribution ring, and a distribution nozzle.

[0051] The second aspect of the present disclosure adopts the down-flow bed reaction system of the first aspect of the present disclosure to perform a method for producing low-carbon olefins and aromatic hydrocarbons by catalytic conversion of light hydrocarbon oil, which includes: introducing a light hydrocarbon oil raw material 102 into a down-flow bed reactor 2 to contact with regenerated catalyst to perform a cracking reaction, to obtain a reaction material containing a cracking reaction product and spent catalyst; introducing the reaction material into a full-closed anti-coking cyclone assembly or a coarse-rotation top-rotation closed direct-connection assembly in a reaction settler 4 through the outlet of the down-flow bed reactor 2 to perform separation treatment, to obtain high-temperature reaction oil gas and spent catalyst material; introducing the spent catalyst material into a stripping section 3 to perform stripping treatment, to obtain spent catalyst; introducing the spent catalyst into a regenerator 6 through a spent catalyst inclined pipe 13 to perform regeneration treatment, to obtain regenerated catalyst; introducing the regenerated catalyst into the down-flow bed reactor 2 through a regenerated catalyst inclined pipe 11; introducing the high-temperature reaction oil gas into an oil gas quenching device 5 to exchange heat with a quenching medium 109, to obtain a cooled reaction oil gas 110; further separating the low-temperature reaction oil, to obtain low-carbon olefins and low-carbon aromatic hydrocarbons, as well as other products and a back-fining medium 101.

[0052] By the above technical scheme, first, the down-flow bed reactor 2 in the gravity field has good gas-solid transfer characteristics, significantly reduces the gas-solid axial back mixing, provides a nearly plug flow environment for the catalytic cracking of light hydrocarbon oil, and can improve the yield of low-carbon olefins and low-carbon aromatic hydrocarbons. Second, the reaction system is independently arranged, has a wide application range, is suitable for small and medium-sized devices, and is also suitable for large and super-large devices, and avoids the safety hidden danger caused by arranging the reactor inside the regenerator 6. Third, the reactor is provided with a fully-closed anti-coking cyclone assembly, which significantly shortens the residence time of high-temperature reaction oil gas in the reaction settler 4, effectively avoids the coking of high-temperature oil gas in the reaction settler 4, and can reduce the non-ideal secondary cracking reaction, improve the yield of the target product, and enhance the anti-fluctuation ability of the device. Fourth, the reaction system is provided with an oil gas quenching device 5, which uses heavy oil as a quenching medium 109, can quickly reduce the temperature of the reaction oil gas, avoids the safety hidden danger caused by excessive thermal cracking and condensation coking of the cooling reaction oil gas 110 in the pipeline, and can effectively utilize the heat in the high-temperature reaction oil gas. Fifth, under the background of the rapid development of electric vehicles, the present application can maximize the catalytic conversion of fuels such as gasoline, naphtha and kerosene into low-carbon olefins (ethylene + propylene) and low-carbon aromatic hydrocarbons (benzene, toluene, xylene) and other basic chemicals, so that the traditional fuel-type refinery or fuel-lubricating oil-type refinery can be transformed into a chemical-type refinery, and the refinery can develop and extend from a single oil refinery to a chemical raw material production, which not only solves the problem of excess finished oil, but also increases the problem of shortage of chemical raw materials, and significantly improves the economic benefit of the enterprise.

[0053] The light hydrocarbon oil feedstock 102 used in the present disclosure is selected from a light fraction with a distillation range of 20-300°C, and is preferably one or more of catalytic cracking gasoline, catalytic cracking gasoline, straight-run naphtha, coking naphtha, thermal cracking naphtha, thermal cracking naphtha, hydrogenated naphtha, reforming raffinate, straight-run kerosene and hydrogenated kerosene.

[0054] The catalyst used in the present disclosure is conventionally selected in the art, and the present application does not have special requirements. For example, the regenerated catalyst includes zeolite, inorganic oxide and clay; the content of the zeolite is 0.5-90% by weight, the content of the inorganic oxide is 1-99% by weight, and the content of the clay is 0-80% by weight, based on the total weight of the regenerated catalyst; the zeolite includes mesoporous zeolite, medium-pore zeolite and optional macroporous zeolite; the content of the mesoporous zeolite is 10-90% by weight, the content of the medium-pore zeolite is 10-90% by weight, and the content of the macroporous zeolite is 0-50% by weight, based on the total weight of the zeolite. The inorganic oxide includes but is not limited to Al2O3, Na2O and SiO2, etc.

[0055] In one embodiment, the method further comprises introducing the recycle medium 101, the regenerated catalyst, the light hydrocarbon oil feedstock 102 and the dilution steam 103 into a downflow bed reactor 2 and moving upwardly through the action of the pre-lift medium 100 and reacting. The downflow bed reactor 2 is operated at the following conditions: the light hydrocarbon oil feedstock 102 preheating temperature is 40-600°C, preferably 100-400°C, more preferably 200-300°C; the reaction temperature is 400-900°C, preferably 500-800°C, more preferably 550-700°C; the reaction pressure is 0.01-1.0 MPa(g), preferably 0.05-0.4 MPa(g), more preferably 0.1-0.2 MPa(g); the reaction time is 0.1-30 s, preferably 1-10 s, more preferably 2-4 s; the mass flow ratio of the regenerated catalyst to the light hydrocarbon oil feedstock 102 is 1-100, preferably 10-50, more preferably 20-40; and the mass flow ratio of the injected steam to the light hydrocarbon oil feedstock 102 is 0.05-2, preferably 0.1-0.5, more preferably 0.2-0.4.

[0056] The pre-lift medium 100 is selected from one or more of the following: steam, nitrogen, catalytic dry gas, self-produced methane hydrogen gas, and light hydrocarbon oil feedstock 102 gas.

[0057] In one embodiment, the operating conditions of the stripping section 3 include: the average gas superficial linear velocity is 0.05-1 m / s, preferably 0.1-0.5 m / s, more preferably 0.2-0.4 m / s; and the average catalyst residence time is 0.5-10 min, preferably 1-5 min, more preferably 2-4 min.

[0058] In one embodiment, the operating conditions of the reaction settler 4 include: the average gas superficial linear velocity is 0.01-1 m / s, preferably 0.03-0.5 m / s, more preferably 0.05-0.2 m / s; and the pressure of the reaction settler 4 is 0-20 kPa higher than that of the stripping section 3, preferably 0.02-10 kPa, more preferably 0.05-5 kPa.

[0059] In one embodiment, the operating conditions of the oil and gas quenching device 5 include: the temperature of the cooled reaction oil and gas at the outlet is 200-550°C, the temperature of the bottom liquid is 200-500°C, and the residence time of the bottom liquid is 0-15 min.

[0060] In one embodiment, the operating conditions of the regenerator 6 include: a temperature of 450℃ to 850℃, preferably 600℃ to 800℃, more preferably 650℃ to 750℃; a pressure of 0.01 to 1.0 MPa(g), preferably 0.1 to 0.4 MPa(g), more preferably 0.12 to 0.28 MPa(g). The main air of the coking drum includes one or more of a mixture of air, oxygen, nitrogen, flue gas, and carbon dioxide.

[0061] In order to reduce the difficulty of device modification, a riser 1 can be added to the device, and the arrangement of the riser 1 can be determined according to the relative elevation of the reactor and the regenerator 6. For example, in one embodiment, the regenerated catalyst enters the lower part of the riser 1 through the regeneration inclined pipe 11, and enters the downflow bed reactor 2 under the action of the lifting medium to contact the light hydrocarbon oil feedstock 102 to perform the cracking reaction. In another embodiment, the spent catalyst enters the lower part of the riser 1 through the spent inclined pipe 13, and enters the regenerator 6 under the action of the lifting medium to perform the regeneration treatment.

[0062] In one embodiment, the method further comprises, when a full-closed anti-coking cyclone assembly is used in the reaction settler 4, the reaction material is subjected to first separation by the cyclone quick separation head 21 at the outlet of the downflow bed reactor 2 to obtain a coarse separation oil gas and a first spent catalyst; the first spent catalyst flows downward in the internal space of the closed cover 22 and flows into the stripping section 3; the coarse separation oil gas flows upward along the internal space of the closed cover 22 and enters the reaction cyclone separator 25 through the flow guide cylinder to perform second separation, to obtain the high-temperature reaction oil gas and the second spent catalyst; after the high-temperature reaction oil gas enters the reaction gas collecting chamber 27 from the gas phase outlet of the reaction cyclone separator 25, it enters the oil gas quenching device 5, and the second spent catalyst flows into the gas phase space formed by the outer wall of the closed cover 22 and the sealing cover plate 23 from the catalyst outlet of the reaction cyclone separator 25, and finally enters the stripping section 3 through the slot 24.

[0063] In one embodiment, the method further comprises, when a full-closed anti-coking cyclone assembly is used in the reaction settler 4, the reaction material is subjected to first separation by the cyclone quick separation head 21 at the outlet of the downflow bed reactor 2 to obtain a coarse separation oil gas and a first spent catalyst; the first spent catalyst flows downward in the internal space of the closed cover 22 and flows into the stripping section 3; the coarse separation oil gas flows upward along the internal space of the closed cover 22 and enters the reaction cyclone separator 25 through the flow guide cylinder to perform second separation, to obtain the high-temperature reaction oil gas and the second spent catalyst; after the high-temperature reaction oil gas enters the reaction gas collecting chamber 27 from the gas phase outlet of the reaction cyclone separator 25, it enters the oil gas quenching device 5, and the second spent catalyst flows into the gas phase space formed by the outer wall of the closed cover 22 and the sealing cover plate 23 from the catalyst outlet of the reaction cyclone separator 25, and finally enters the stripping section 3 through the slot 24.

[0064] In the above-mentioned embodiments, in the state that the stripping section 3 is in normal operation, the loosening steam 104 and the stripping steam 105 can be introduced into the stripping section 3 to participate in the stripping treatment; in the state that the reaction settler 4 is in normal operation, the anti-coking steam 106 can be introduced into the reaction settler 4 to prevent coking; in the state that the oil-gas quencher 5 is in normal operation, the stirring steam 108 can be introduced into the oil-gas quencher 5 to perform stirring treatment. The loosening steam 104, the stripping steam 105, the anti-coking steam 106 and the stirring steam 108 are selected from 0.7-1.6 MPa(g) low-pressure steam and / or 1.6-4.6 MPa(g) medium-pressure steam, and are further superheated to 400-700°C, preferably superheated to 480-600°C.

[0065] In one embodiment, in which the reaction product is mixed C4 and / or mixed C5 and / or cracked naphtha, the mixed C4 and / or mixed C5 and / or cracked naphtha is returned to the down-flow bed reactor 2 for reprocessing; the position at which the mixed C4 and / or mixed C5 and / or cracked naphtha is introduced into the down-flow bed reactor 2 is before and / or after the light hydrocarbon oil feedstock nozzle; through reprocessing of the mixed C4, mixed C5 and cracked naphtha, the yield of low-carbon olefins and low-carbon aromatic hydrocarbons can be further improved.

[0066] The method provided by the present application is further described below through specific examples, but the present application is not limited by the examples. The catalyst used in the examples has the properties shown in Table 1, and the feedstock used in the examples has the properties shown in Table 2.

[0067] Table 1 Catalyst properties

[0068]

[0069] Table 2 Properties of light hydrocarbon oil feedstock

[0070]

[0071] Example 1

[0072] The system for catalytically converting the light hydrocarbon oil used in the example to produce low-carbon olefins and aromatic hydrocarbons is shown in Figure 1

[0073] Taking the light hydrocarbon oil feedstock 102 (mixed components of straight-run naphtha, straight-run kerosene and coking naphtha) with a feedstock amount of 0.9 million tons / year as an example, the method for catalytically converting the light hydrocarbon oil to produce low-carbon olefins and aromatic hydrocarbons includes:

[0074] After the light hydrocarbon oil feedstock 102 is preheated to 300°C, the light hydrocarbon oil feedstock 102 is introduced into the down-flow bed reactor 2 to contact with the regenerated catalyst to perform a cracking reaction, and a reaction material containing a cracking reaction product and spent catalyst is obtained.

[0075] ​The reaction material is subjected to a first separation by a cyclone quick separation head 21 at the outlet of the downflow bed reactor 2 to obtain a crude separation oil gas and a first spent catalyst; the first spent catalyst is allowed to flow downward in the interior space of the closed cover 22 and flows into the stripping section 3; the crude separation oil gas is allowed to flow upward along the interior space of the closed cover 22 and enters the reaction cyclone separator 25 to be separated to obtain the high-temperature reaction oil gas and the second spent catalyst; the high-temperature reaction oil gas enters the reaction gas collection chamber 27 from the gas phase outlet of the reaction cyclone separator 25, and the second spent catalyst flows into the gas phase space formed by the outer wall of the closed cover 22 and the sealing cover plate 23 from the catalyst outlet of the reaction cyclone separator 25 and finally enters the stripping section 3 through the slot 24.

[0076] The high-temperature reaction oil gas enters the oil gas quenching device 5 from the reaction gas collection chamber 27, is cooled to 350°C by the heat-removed oil slurry, and then enters the product separation unit to be separated to obtain low-carbon olefins (ethylene, propylene), low-carbon aromatic hydrocarbons (benzene, toluene, xylene), methane hydrogen, ethane, propane, mixed carbon four, mixed carbon five, cracked naphtha, cracked light oil, cracked heavy oil, and other products. Part of the mixed carbon four, mixed carbon five, and cracked naphtha is returned to the downflow bed reactor 2 for reprocessing to increase the yield of low-carbon olefins and low-carbon aromatic hydrocarbons. The spent catalyst separated by the fully-closed anti-coking cyclone assembly flows downward into the stripping section 3, is stripped of the entrained oil gas, and then flows into the regeneration device through the spent catalyst inclined pipe 13, is introduced into the coking main air through the main air distributor 15 for coking regeneration, and then the obtained regenerated catalyst flows into the riser 1 through the regenerated catalyst inclined pipe 11 and is returned to the downflow bed reactor 2 through the lifting medium for circulation.

[0077] The operating conditions of the method are shown in Table 3, and the product distribution of the device is shown in Table 4.

[0078] Example 2

[0079] The system for catalytically converting light hydrocarbon oil to produce low-carbon olefins and aromatic hydrocarbons used in this example is shown in Figure 2 ;

[0080] The method for catalytically converting light hydrocarbon oil to produce low-carbon olefins and aromatic hydrocarbons is the same as in Example 1, except that the reaction material is subjected to treatment by a coarse cyclone top cyclone closed direct connection assembly, which specifically includes: the reaction material is subjected to a first separation by a coarse cyclone 121 to obtain a crude separation oil gas and a first spent catalyst; the crude separation oil gas is subjected to separation by a reaction cyclone separator 25 to obtain the high-temperature reaction oil gas and the second spent catalyst; the high-temperature reaction oil gas enters the reaction gas collection chamber 27 from the gas phase outlet of the reaction cyclone separator 25; and the first spent catalyst and the second spent catalyst at the catalyst outlet of the coarse cyclone 121 and the catalyst outlet of the reaction cyclone separator 25 enter the stripping section 3.

[0081] The operating conditions of the process are shown in Table 3; the product distribution of the unit is shown in Table 4.

[0082] Example 3

[0083] The system for catalytic conversion of light hydrocarbon oil to produce low carbon olefins and aromatic hydrocarbons used in this example is shown in Figure 3 ;

[0084] The process for catalytic conversion of light hydrocarbon oil to produce low carbon olefins and aromatic hydrocarbons is the same as in Example 1, except that,

[0085] The spent catalyst is made to enter the riser 1 through the spent catalyst inclined pipe 13 and enter the regeneration device for coke burning regeneration under the action of the lifting medium; the regenerated catalyst is directly made to enter the downflow bed reactor 2 for reaction through the regenerated inclined pipe 11.

[0086] The operating conditions of the process are shown in Table 3; the product distribution of the unit is shown in Table 4.

[0087] Example 4

[0088] The system for catalytic conversion of light hydrocarbon oil to produce low carbon olefins and aromatic hydrocarbons used in this example is shown in Figure 4 ;

[0089] The process for catalytic conversion of light hydrocarbon oil to produce low carbon olefins and aromatic hydrocarbons is the same as in Example 2, except that,

[0090] The spent catalyst is made to enter the riser 1 through the spent catalyst inclined pipe 13 and enter the regeneration device for coke burning regeneration under the action of the lifting medium; the regenerated catalyst is directly made to enter the downflow bed reactor 2 for reaction through the regenerated inclined pipe 11.

[0091] The operating conditions of the process are shown in Table 3; the product distribution of the unit is shown in Table 4.

[0092] Comparative Example 1

[0093] The method for producing low-carbon olefins and aromatic hydrocarbons by catalytic conversion of light hydrocarbon oil according to the method of patent CN103509589A specifically comprises: using straight-run naphtha as a raw material, performing a test on a middle-sized device of a riser reactor, preheating the raw material oil to enter the bottom of the riser reactor, performing a cracking reaction under the conditions of a reaction temperature of 675 DEG C, a reaction time of 2 seconds, a weight ratio of the catalytic cracking catalyst to the raw material oil of 25, and a weight ratio of the water vapor to the raw material oil of 0.55, the reaction product, water vapor, and spent catalyst entering a closed cyclone from the outlet of the reactor, rapid separation of the reaction product and the catalyst, the reaction product being cut according to the distillation range after heat exchange with the raw material in a separation system, so as to obtain dry gas, propylene, carbon four, and gasoline fractions, etc. The spent catalyst enters a regenerator under the action of gravity, and is regenerated by contacting with air. The regenerated catalyst enters a degassing tank to remove non-hydrocarbon gas impurities adsorbed and carried by the regenerated catalyst. The stripped regenerated catalyst is returned to the riser reactor for recycling.

[0094] The operating conditions of the method are shown in Table 3; and the product distribution of the device is shown in Table 4.

[0095] Table 3 Operating conditions

[0096]

[0097] Table 4 Product distribution of the device

[0098]

[0099] As shown in Table 4, according to the comparison of the data of Examples 1-4 and Comparative Example 1, it can be known that, by using the technical solution of the present disclosure, the production of low-carbon olefins and aromatic hydrocarbons by catalytic conversion of light hydrocarbon oil can be realized, and the risk of coking of high-temperature oil gas in the reaction settler can be reduced, and at the same time, the yield of the target product can be improved.

[0100] The preferred embodiments of the present disclosure are described in detail above in combination with the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solution of the present disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0101] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combination manners are not described again in the present disclosure.

[0102] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed by the present disclosure.

Claims

1. A descending bed reaction system for the catalytic conversion of light hydrocarbon oils to produce low-carbon olefins and aromatics, characterized in that, The descending bed reaction system includes a descending bed reactor (2), a reaction product purification and separation unit, an oil-gas quencher (5), and a regenerator (6); the reaction product purification and separation unit and the oil-gas quencher (5) are coaxially arranged, and the oil-gas quencher (5) is located at the top of the reaction product purification and separation unit; the reaction product purification and separation unit includes a stripping section (3) and a reaction settling tank (4) from bottom to top, and the stripping section (3) and the reaction settling tank (4) are separated by a sealing cover plate (23); the descending bed reactor (2) and the reaction product purification and separation unit are arranged side by side; The reaction settling tank (4) is equipped with a fully enclosed anti-coking cyclone assembly; the fully enclosed anti-coking cyclone assembly includes a cyclone fast separator head (21), a sealing cover (22), and a reaction cyclone separator (25); the sealing cover (22) is a sealed cylinder located on the upper part of the reaction settling tank (4); the outlet of the upper part of the sealing cylinder is connected to the inlet of the reaction cyclone separator (25) through a guide tube; the lower part of the sealing cylinder extends downward through the sealing cover plate (23) into the stripping section (3), and the lower part of the sealing cover (22) is provided with a slot (24) so ​​that the inner and outer sides of the sealing cover (22) are connected only through the slot (24); the bottom of the descending bed reactor (2) is embedded inside the reaction product purification and separation unit, and the bottom of the descending bed reactor (2) extends into the sealing cylinder, and the cyclone fast separator head (21) is located at the bottom outlet of the descending bed reactor (2); or, The reaction settling tank (4) is equipped with a coarse vortex top-vortex sealed direct connection assembly; the coarse vortex top-vortex sealed direct connection assembly includes a coarse vortex (121), an oil-gas manifold (122), an oil-gas sealed guide pipe (124), and a reaction cyclone separator (25); the bottom outlet of the descending bed reactor (2) is connected to the interior of the oil-gas manifold (122) through the coarse vortex (121); the gas outlet of the oil-gas manifold (122) is connected to the inlet of the reaction cyclone separator (25); the bottom inlet of the oil-gas sealed guide pipe (124) extends downward through the sealing cover plate (23) to the upper gas phase space of the stripping section (3); the gas phase space below the sealing cover plate (23) is connected to the oil-gas manifold (122) through the oil-gas sealed guide pipe (124) and the oil-gas manifold (122); The regenerator (6) includes a catalyst inlet and a catalyst outlet; the stripping section (3) includes a catalyst outlet, and the descending bed reactor (2) includes a catalyst inlet; the catalyst outlet of the stripping section (3) is connected to the catalyst inlet of the regenerator (6) through a catalyst inlet tube (13); the catalyst inlet of the descending bed reactor (2) is connected to the catalyst outlet of the regenerator (6) through a catalyst inlet tube (11).

2. The descending bed reaction system according to claim 1, characterized in that, The downward bed reaction system also includes a riser tube (1) of equal diameter cylindrical shape; The lower part of the riser (1) is provided with a regenerated catalyst inlet for communication with the outlet of the regenerated inclined tube (11); the top outlet of the riser (1) is connected to the top inlet of the descending bed reactor (2); or, The lower part of the riser tube (1) is provided with a catalyst inlet and the upper part is provided with a catalyst outlet; the catalyst inlet of the riser tube (1) is connected to the outlet of the catalyst inclined tube (13), and the catalyst outlet of the riser tube (1) is connected to the catalyst inlet of the regenerator (6).

3. The descending bed reaction system according to claim 1, characterized in that, The reaction settling device (4) is also provided with a reaction gas collection chamber (27); the outlet of the reaction gas collection chamber (27) is connected to the top outlet of the reaction settling device (4); The reaction cyclone separator (25) is two-stage or more; The outlet of the guide tube is connected to the inlet of the first-stage reaction cyclone separator; the gas outlet of the last-stage reaction cyclone separator is connected to the inlet of the reaction gas collection chamber (27); the catalyst outlet of the reaction cyclone separator (25) extends downward through the material leg through the sealing cover plate (23) to the outer wall of the enclosure (22) and the gas phase space formed by the sealing cover plate (23); or, The gas outlet of the oil and gas manifold (122) is connected to the inlet of the first-stage reaction cyclone separator; the gas outlet of the last-stage reaction cyclone separator is connected to the inlet of the reaction gas collection chamber (27); the catalyst outlet of the coarse cyclone (121) and the catalyst outlet of the reaction cyclone separator (25) extend downward to the gas phase space through the material leg through the sealing cover plate (23).

4. The descending bed reaction system according to claim 1, characterized in that, The stripping section (3) includes stripping section internal components (18), at least one set of stripping steam rings (19) and loose steam rings (20); The stripping section internal components (18) include one or more of the following: herringbone baffle, annular baffle, disc-shaped baffle, packing and grid; The stripping steam ring (19) is located in the middle and / or lower part of the stripping section (3) and the stripping steam ring (19) is used to communicate with the stripping steam source; The loose steam ring (20) is located at the bottom of the stripping section (3) and the loose steam ring (20) is used to communicate with the loose steam source; The upper and / or lower surfaces of the stripping steam ring (19) and the loosening steam ring (20) are provided with steam wear-resistant nozzles.

5. The descending bed reaction system according to claim 1, characterized in that, The oil-gas quencher (5) includes an oil-gas distributor (28), a quencher baffle (29), a quenching medium distributor (30), and a stirring steam ring (31). The oil-gas distributor (28) is located at the bottom of the oil-gas quencher (5) and the top outlet of the reaction settling device (4) is connected to the inlet of the oil-gas distributor (28). The quench cooler baffle (29) is located above the oil-gas distributor (28); the number of layers of the quench cooler baffle (29) is 1 to 20. The quench medium distributor (30) is located above the quench baffle (29); the lower surface of the quench medium distributor (30) has injection holes, and the airflow direction of the injection holes of the quench medium distributor (30) is vertically downward and / or obliquely downward. The stirring steam ring (31) is located at the lower part of the oil-gas quencher (5); the upper surface of the stirring steam ring (31) is provided with injection holes, and the airflow direction of the injection holes of the stirring steam ring (31) is vertically upward and / or obliquely upward.

6. A method for catalytic conversion of light hydrocarbon oils to produce low-carbon olefins and aromatics using the descending bed reaction system according to any one of claims 1 to 5, characterized in that, The method includes: Light hydrocarbon oil feedstock is fed into a downward bed reactor (2) and comes into contact with a regenerated catalyst to carry out a cracking reaction, thereby obtaining a reaction material containing cracking reaction products and a regenerated catalyst. The reactants are separated by a fully enclosed anti-coking cyclone assembly or a coarse cyclone top cyclone closed direct connection assembly in the reaction settling tank (4) through the outlet of the downflow bed reactor (2) to obtain high-temperature reaction oil and gas and catalyst material to be generated. The raw catalyst material is fed into the stripping section (3) for stripping treatment to obtain the raw catalyst; the raw catalyst is fed into the regenerator (6) through the raw catalyst inclined tube (13) for regeneration treatment to obtain the regenerated catalyst; the regenerated catalyst is returned to the descending bed reactor (2) through the regeneration inclined tube (11). The high-temperature reaction oil and gas are introduced into the oil and gas quencher (5) to exchange heat with the quenching medium, and the cooled reaction oil and gas are obtained; the cooled reaction oil and gas are further separated to obtain low-carbon olefins and low-carbon aromatics.

7. The method according to claim 6, characterized in that, The light hydrocarbon oil feedstock is selected from light fractions with a distillation range of 20–300°C; The regenerated catalyst comprises zeolite, inorganic oxides, and clay; based on the total weight of the regenerated catalyst, the zeolite content is 0.5–90 wt%, the inorganic oxide content is 1–99 wt%, and the clay content is 0–80 wt%; the zeolite comprises mesoporous zeolite and mesoporous zeolite; based on the total weight of the zeolite, the mesoporous zeolite content is 10–90 wt%, and the mesoporous zeolite content is 10–90 wt%. The quenching medium is selected from heavy oil products with an initial boiling point of 300°C or higher.

8. The method according to claim 7, characterized in that, The light hydrocarbon oil feedstock is selected from one or more of the following: catalytic cracking gasoline, catalytic pyrolysis gasoline, straight-run naphtha, coking naphtha, thermally cracked naphtha, thermally cracked naphtha, hydrotreated naphtha, reforming residue oil, straight-run kerosene, and hydrotreated kerosene. The zeolite also includes macroporous zeolite; based on the total weight of the zeolite, the content of macroporous zeolite is 0-50% by weight%. The quenching medium is selected from one or more of the following: cracked heavy oil, catalytic cracking slurry oil, catalytic cracking slurry oil, coking slurry oil, atmospheric residue oil, and vacuum residue oil.

9. The method according to claim 6, characterized in that, The reaction conditions for the pyrolysis reaction include: a preheating temperature of 40–600°C, a reaction temperature of 400–900°C, a reaction pressure of 0.01–1.0 MPaG, a reaction time of 0.1–30 s, a mass flow rate ratio of the regenerated catalyst to the light hydrocarbon feedstock of 1–100, and a mass flow rate ratio of steam to the light hydrocarbon feedstock of 0.05–2. The operating conditions of the stripping section (3) include: the average apparent linear velocity of the gas is 0.05 to 1 m / s, and the average residence time of the catalyst is 0.5 to 10 min; The operating conditions of the oil-gas quencher (5) include: the outlet reaction oil-gas temperature is 200-550℃, the bottom liquid temperature is 200-500℃, and the bottom liquid residence time is 0-15min.

10. The method according to claim 6, characterized in that, The regenerated catalyst is introduced into the lower part of the riser (1) through the regeneration inclined tube (11), and then enters the descending bed reactor (2) under the action of the lifting medium to contact the light hydrocarbon feedstock for the cracking reaction; or, The catalyst to be generated is introduced into the lower part of the riser tube (1) through the prepared inclined tube (13), and then enters the regenerator (6) for regeneration under the action of the rising medium.

11. The method according to claim 6, characterized in that, The method further includes: allowing the reactants to undergo a first separation through a cyclone separator (21) at the outlet of the downflow bed reactor (2) to obtain coarse oil gas and a first catalyst to be generated; allowing the first catalyst to flow downward through the internal space of the sealed cover (22) and into the stripping section (3); allowing the coarse oil gas to flow upward along the internal space of the sealed cover (22) and enter the reaction cyclone separator (25) through the guide tube for a second separation to obtain the high-temperature reaction oil gas and the second catalyst to be generated; allowing the high-temperature reaction oil gas to enter the oil gas quencher (5) from the gas phase outlet of the reaction cyclone separator (25), and allowing the second catalyst to flow from the catalyst outlet of the reaction cyclone separator (25) into the gas phase space formed by the outer wall of the sealed cover (22) and the sealing cover plate (23), and finally enter the stripping section (3) through the slot (24); or, The method further includes: subjecting the reactants to a first separation via a coarse cyclone (121) to obtain coarse oil and gas and a first catalyst to be generated; subjecting the coarse oil and gas to a second separation via a reaction cyclone separator (25) to obtain the high-temperature reaction oil and gas and the second catalyst to be generated; subjecting the high-temperature reaction oil and gas to an oil and gas quencher (5) via the gas phase outlet of the reaction cyclone separator (25); and subjecting the first catalyst to be generated at the catalyst outlet of the coarse cyclone (121) and the second catalyst to be generated at the catalyst outlet of the reaction cyclone separator (25) to the stripping section (3).

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