A system and method for producing light olefins from hydrocarbon oil feedstock

Abstract

The present application relates to a kind of system and method for producing low carbon olefin of hydrocarbon oil raw material, the system includes upflow reactor and downflow reactor;The oil agent outlet of upflow reactor is in fluid communication with the oil agent entrance of downflow reactor;The bottom of upflow reactor is respectively provided with raw oil feeding nozzle and first catalyst delivery pipe;The top of downflow reactor is provided with second catalyst delivery pipe;The bottom of downflow reactor is provided with oil agent separation device.The present application first carries out first catalytic cracking reaction in upflow reactor to generate a large number of olefin-rich intermediate components when hydrocarbon oil raw material produces low carbon olefin, then introduce second catalyst in downflow reactor and carry out second catalytic cracking reaction with higher temperature, the yield and selectivity of low carbon olefin are significantly improved;The combination of first uplink and then downlink makes heavy component dispersion uniform to avoid deposition, and the contact with catalyst is good, and can be applied to more extensive raw oil.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum refining and petrochemical processing, and in particular to a system and method for producing light olefins from hydrocarbon oil raw materials. Background Art

[0002] As an important secondary crude oil processing technology, catalytic cracking technology holds an irreplaceable position in the production of clean oil products and light olefins, characterized by its wide feedstock adaptability, high heavy oil conversion rate, and flexible product solutions. Recent development and trends in catalytic cracking technology for chemical feedstock production indicate that major oil companies and research institutions have shifted their focus from increasing light olefin yields to improving light olefin selectivity. In this process, researchers are developing new processes based on optimally matching hydrocarbon cracking performance with reaction temperature, reaction time, and catalyst performance.

[0003] The catalytic cracking unit is a self-heating device, where heat is transferred between the reaction and regeneration systems via the supported catalyst. This makes the regulation of reaction temperature inseparable from the circulation of the catalyst. In addition to providing the heat required for the catalytic cracking reaction, the catalyst also plays a crucial role in providing active centers for the reaction. As the cracking reaction occurs, the heat capacity of the catalyst particles decreases in tandem with the active centers. However, as the cracking reaction progresses, further cracking of small hydrocarbon molecules requires higher reaction temperatures. Researchers have also investigated how to best match reaction temperature and catalyst activity to the cracking properties of hydrocarbon molecules.

[0004] CN107557063 discloses a method for catalytic conversion of low-quality crude oil. This method utilizes a two-stage riser reactor. A portion of the spent catalyst is removed through a central expansion section, while a portion of the regenerated catalyst is added. This method allows for segmented control of the reaction depth and optimizes catalyst activity. However, this method uses a method that reduces the linear velocity and extends the reaction time in the expansion section to remove the catalyst. This increases the residence time of the oil and gas in the expansion section, significantly increases side reactions, and reduces the selectivity of the target product.

[0005] CN105368493 discloses a catalytic conversion method for producing high-octane gasoline. This method involves initially cracking the crude oil with a cooled regeneration agent at a relatively low temperature for a relatively short time. Subsequently, a higher temperature regeneration agent is added, and the cracking reaction is continued at a temperature 5-100°C higher than that in the initial reaction zone for a longer reaction time. This method controls the cracking depth by separately controlling the reaction severity in each riser reactor reaction zone. However, in this method, the carbonized catalyst after reaction in the initial reaction zone is completely transferred to the main reaction zone, which increases the proportion of hydrocarbons reacting on the deactivated catalyst and reduces the selectivity of the target product.

[0006] CN107337574 discloses a catalytic conversion method for producing olefins by cracking light hydrocarbons. This method uses spent catalyst drawn from a stripper or reacted catalyst drawn from a reactor to return to a pre-contact zone. After the light hydrocarbon feedstock is vaporized in the pre-contact zone, it enters the main reaction zone where it contacts the regenerated catalyst for high-temperature cracking. This method combines low-temperature pre-gasification with high-temperature cracking, optimizing the reactor's temperature distribution. However, due to the low reaction temperature in the pre-contact zone, this method not only vaporizes the light hydrocarbons but also hinders cracking reactions. This significantly reduces the catalyst-to-oil ratio in the main reaction zone, resulting in a low yield of low-carbon olefins from the cracking of the light hydrocarbons.

[0007] CN110240932 discloses a multi-stage fluidized catalytic reaction method and reactor for petroleum hydrocarbons. This method involves contacting and reacting feedstock oil and regenerated catalyst in a first reaction zone. After some of the catalyst is swirled out, the oil and gas continue through a delivery pipe to a second reaction zone where they react with a second catalyst replenished in a third reaction zone. The oil and gas in the first reaction zone continue to undergo cracking reactions under the new catalyst. Light hydrocarbons and light cycle oil react with the second catalyst in the third reaction zone, and the resulting oil enters the second reaction zone where it continues to undergo catalytic cracking. This method enables catalyst replacement, gradient control of the reaction temperature, and control of the carbon content of the regenerated catalyst. However, because the third reaction zone is located below the second reaction zone, the oil and gas in the first reaction zone can undergo severe thermal cracking reactions as they pass through the high-temperature third reaction zone, resulting in the production of large amounts of dry gas.

[0008] CN108753356 discloses a multi-stage countercurrent catalytic cracking / cracking system and method. This method utilizes at least two descending fluidized bed reactors and at least two gas-solid rapid separation devices arranged in a stepped configuration. The discharge port of each descending fluidized bed reactor is connected to the gas-solid mixed phase inlet of the corresponding gas-solid rapid separation device, and the gas outlet of the corresponding gas-solid rapid separation device of each descending fluidized bed reactor is connected to the feed port of the corresponding descending fluidized bed reactor of the previous stage. This method can provide different temperature fields and catalyst activity fields for each stage of the reaction, which is beneficial for improving the selectivity of hydrocarbon catalytic cracking / cracking. However, this method cannot flexibly control the temperature and catalyst activity according to the hydrocarbon cracking performance, which has significant operational limitations.

[0009] In the process of producing light olefins from hydrocarbon oil raw materials, how to match the cracking properties of hydrocarbon molecules and flexibly control the reaction temperature and catalyst activity to improve the yield and selectivity of light olefins is a technical problem that needs to be solved urgently. Summary of the Invention

[0010] The purpose of the present invention is to provide a system and method for producing light olefins from hydrocarbon oil feedstock, so as to improve the yield and selectivity of light olefins.

[0011] In a first aspect, the present application relates to a system for producing low-carbon olefins from a hydrocarbon oil feedstock, the system comprising an upflowing reactor and a downflowing reactor; an oil agent outlet of the upflowing reactor is in fluid communication with an oil agent inlet of the downflowing reactor; a bottom of the upflowing reactor is provided with a feedstock oil feed nozzle and a first catalyst delivery pipe, respectively; a top of the downflowing reactor is provided with a second catalyst delivery pipe; a bottom of the downflowing reactor is provided with an oil agent separation device, an oil agent inlet of the oil agent separation device is in communication with an oil agent outlet of the downflowing reactor, the oil agent separation device is provided with an oil gas output pipe and a second spent catalyst output pipe; the oil gas output pipe is connected with an oil gas separation device; the upflowing reactor and the downflowing reactor are configured such that an outlet temperature of the downflowing reactor is 10-100°C higher than an outlet temperature of the upflowing reactor.

[0012] Optionally, the oil agent outlet of the upflowing reactor and the oil agent inlet of the downflowing reactor are in communication through an oil agent delivery pipe; the second spent catalyst output pipe is connected with a first stripper and a first regenerator; the first catalyst delivery pipe and the second catalyst delivery pipe are respectively connected with a catalyst outlet of the first regenerator.

[0013] Optionally, the system is further provided with a gas-solid quick separation device, an inlet of the gas-solid quick separation device is in communication with the oil agent outlet of the upflowing reactor, a gas outlet of the gas-solid quick separation device is in communication with the oil agent inlet of the downflowing reactor; preferably, the system is further provided with a second stripper and a second regenerator, the second stripper is provided with a stripping vapor input pipe, a first spent catalyst output pipe and a stripped oil gas delivery pipe, a solid outlet of the gas-solid quick separation device is in communication with a solid inlet of the second stripper, an outlet of the first spent catalyst output pipe is in communication with an inlet of the second regenerator, the stripped oil gas delivery pipe is in communication with an upper portion of the downflowing reactor.

[0014] Optionally, the second spent catalyst output pipe is connected with a third stripper and a third regenerator; an inlet of the first catalyst delivery pipe is in communication with a catalyst outlet of the second regenerator, a catalyst outlet of the third regenerator and the second spent catalyst output pipe, respectively; an inlet of the second catalyst delivery pipe is in communication with the catalyst outlet of the second regenerator and the catalyst outlet of the third regenerator, respectively.

[0015] Optionally, the upflowing reactor is a single or composite reactor of an equal-diameter or variable-diameter riser reactor and a fast bed reactor, and the downflowing reactor is an equal-diameter or variable-diameter straight pipe.

[0016] In a second aspect, the present application relates to a method for producing low-carbon olefins from a hydrocarbon oil feedstock, the method comprising:

[0017] (1) contacting a feedstock oil with a first catalyst in an upward reactor to carry out a first catalytic cracking reaction to obtain a first oil-agent mixture, wherein the first oil-agent mixture comprises a first reaction oil gas and a first catalyst to be regenerated; (2) contacting the first reaction oil gas with a second catalyst in a downward reactor to carry out a second catalytic cracking reaction to obtain a second oil-agent mixture; (3) separating the second oil-agent mixture to obtain a second reaction oil gas and a second catalyst to be regenerated, and separating the second reaction oil gas to obtain light olefins; wherein the outlet temperature of the downward reactor is 10-100°C higher than the outlet temperature of the upward reactor.

[0018] Optionally, the upward reactor and the downward reactor are directly connected through an oil agent delivery pipe, and the first oil agent mixture containing the first reaction oil gas is directly delivered to the downward reactor through the oil agent delivery pipe, so that the first reaction oil gas contacts the second catalyst in the downward reactor to carry out the second catalytic cracking reaction.

[0019] Optionally, the method further comprises: stripping and regenerating the second spent catalyst; and the first catalyst and the second catalyst are each independently selected from a regenerated catalyst and / or a cooled regenerated catalyst.

[0020] Optionally, a gas-solid quick separation device is provided between the upward reactor and the downward reactor, and the first oil agent mixture is separated into the first reaction oil gas and the first catalyst to be generated through the gas-solid quick separation device; the first reaction oil gas is transported to the downward reactor so that the first reaction oil gas and the second catalyst contact in the downward reactor to carry out the second catalytic cracking reaction.

[0021] Optionally, the method further includes: stripping and regenerating the first spent catalyst separated by the gas-solid quick separation equipment; stripping and regenerating the second spent catalyst; the second catalyst is a regenerated catalyst and / or a cooled regenerated catalyst.

[0022] Optionally, the first catalyst is selected from a combination of one or more of a regenerated catalyst, a cooled regenerated catalyst and the second catalyst to be regenerated; preferably, the first catalyst is a combination of the regenerated catalyst and the second catalyst to be regenerated; further preferably, the first catalyst is the second catalyst to be regenerated.

[0023] Optionally, the residence time of the first oil-agent mixture in the gas-solid quick separation device is less than 0.05 s; preferably, the residence time of the first oil-agent mixture in the gas-solid quick separation device is less than 0.03 s.

[0024] Optionally, in step (1), the outlet temperature of the upward reactor is 500-650°C, the oil and gas residence time is 0.5-5s; the weight ratio of the first catalyst to the feedstock oil is (1-50):1; preferably, the outlet temperature of the upward reactor is 530-600°C, the oil and gas residence time is 1.0-2.0s; the weight ratio of the first catalyst to the feedstock oil is (10-30):1.

[0025] Optionally, in step (2), the outlet temperature of the downward reactor is 550-700° C., the oil and gas residence time is 0.1-2 s; the weight ratio of the second catalyst to the feedstock oil is (5-50):1;

[0026] Preferably, the outlet temperature of the downward reactor is 560-650° C., the oil and gas residence time is 0.5-1.0 s; and the weight ratio of the second catalyst to the feedstock oil is (10-30):1.

[0027] Optionally, the feedstock oil is selected from a combination of one or more of crude oil, atmospheric wax oil, vacuum wax oil, atmospheric residue oil, vacuum residue oil, deasphalted oil, hydrogenated heavy oil and coker wax oil; or is selected from a combination of partial fractions or full fractions of one or more of coal liquefaction oil, oil sands oil, shale oil, synthetic oil, animal and plant oils and fats.

[0028] Beneficial effects:

[0029] 1. The present invention produces light olefins from hydrocarbon oil feedstock by first undergoing a first catalytic cracking reaction in an ascending reactor to generate a large amount of olefin-rich intermediate components. A second catalyst is then introduced into a descending reactor to undergo a second catalytic cracking reaction at a higher temperature to convert the intermediate components into light olefins with high selectivity, significantly improving the yield and selectivity of light olefins.

[0030] 2. The upward and then downward combination method can evenly disperse the heavy components to avoid sedimentation, has good contact with the catalyst, and can be applied to a wider range of crude oils. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of a specific embodiment of the system for producing light olefins from hydrocarbon oil feedstock of the present invention;

[0032] Figure 2 This is a schematic structural diagram of another specific embodiment of the system for producing light olefins from hydrocarbon oil feedstock of the present invention;

[0033] Description of Reference Numerals

[0034] 1 Upward reactor; 2 Downward reactor; 3 Oil delivery pipe; 4 Second stripper;

[0035] 5 oil agent separation device; 11 raw oil feed nozzle; 12 first catalyst delivery pipe;

[0036] 13 gas-solid quick separation equipment; 21 second catalyst delivery pipe; 41 stripping steam input pipe;

[0037] 42 first catalyst to be generated output pipe; 43 stripping oil and gas transmission pipe; 51 oil and gas output pipe;

[0038] 52 is a second catalyst output pipe to be generated. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below through the accompanying drawings and examples, through which the features and advantages of the present application will become more clear and distinct.

[0040] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0041] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0042] In the first aspect, the present invention relates to a system for producing light olefins from hydrocarbon oil feedstock, such as Figure 1 and 2 As shown, the system includes an upward reactor 1 and a downward reactor 2; the oil agent outlet of the upward reactor 1 is fluidically connected to the oil agent inlet of the downward reactor 2; the bottom of the upward reactor 1 is respectively provided with a raw oil feed nozzle 11 and a first catalyst delivery pipe 12; the top of the downward reactor 2 is provided with a second catalyst delivery pipe 21; the bottom of the downward reactor 2 is provided with an oil agent separation device 5, the oil agent inlet of the oil agent separation device 5 is connected to the oil agent outlet of the downward reactor 2, and the oil agent separation device 5 is provided with an oil and gas output pipe 51 and a second catalyst output pipe 52 to be generated; the oil and gas output pipe 51 is connected to the oil and gas separation device; the upward reactor 1 and the downward reactor 2 are configured so that the outlet temperature of the downward reactor 2 is 10-100°C higher than the outlet temperature of the upward reactor 1.

[0043] In a second aspect, the present invention relates to a method for producing light olefins from a hydrocarbon oil feedstock, the method comprising: (1) contacting the feedstock oil with a first catalyst in an upward reactor to carry out a first catalytic cracking reaction to obtain a first oil-agent mixture, wherein the first oil-agent mixture comprises a first reaction oil gas and a first catalyst to be regenerated; (2) contacting the first reaction oil gas with a second catalyst in a downward reactor to carry out a second catalytic cracking reaction to obtain a second oil-agent mixture; (3) separating the second oil-agent mixture to obtain a second reaction oil gas and a second catalyst to be regenerated, and separating the second reaction oil gas to obtain light olefins; wherein the outlet temperature of the downward reactor is 10-100°C higher than the outlet temperature of the upward reactor.

[0044] It should be noted that the system described in the first aspect of the present invention is applicable to the method described in the second aspect of the present invention. During catalytic cracking, first, feedstock enters the ascending reactor 1 through the feedstock feed nozzle 11 under the water vapor atomizing medium. The first catalyst enters the ascending reactor 1 through the first catalyst delivery pipe 12. The feedstock and the first catalyst rapidly contact in the ascending reactor to undergo a first catalytic cracking reaction, producing a first oil-agent mixture comprising the first reaction oil gas and the first spent catalyst. Then, the first reaction oil gas (the first oil-agent mixture comprising the first reaction oil gas and the first spent catalyst, or the separated first reaction oil gas) contacts the second catalyst introduced through the second catalyst delivery pipe 21 in the descending reactor 2 to undergo a second catalytic cracking reaction, producing a second oil-agent mixture. The second oil-agent mixture is separated into the second reaction oil gas and the second spent catalyst by the oil-agent separation device 5. The second reaction oil gas is delivered to the oil-gas separation device via the oil-gas output pipe 51, where it is separated into dry gas, liquefied gas, gasoline, diesel, and oil slurry. The second spent catalyst is discharged via the second spent catalyst output pipe 52.

[0045] It should be noted that during the catalytic cracking process, heavy components such as colloids and asphaltenes in the crude oil are preferentially adsorbed on the active centers of the catalyst, but these colloids and asphaltenes often cover the active centers in the form of coke, resulting in reduced catalyst activity and reduced selectivity for cracking of other hydrocarbons. The present invention first pre-cracks hydrocarbons in an upward reactor to generate a large amount of olefin-rich intermediate components, namely the first reaction oil and gas, and at the same time supplements a second catalyst, using a higher reaction temperature to further convert the intermediate components into light olefins with high selectivity. The present invention adopts a combined reactor type of an upward reactor and a downward reactor, and at the same time, a high-temperature and high-activity second catalyst can be introduced into the downward reactor to allow a higher temperature catalytic cracking reaction to be carried out in the downward reactor, and the reaction temperature and catalyst activity can be flexibly adjusted to match the cracking performance of different hydrocarbon molecules in the catalytic cracking process, which is beneficial to improving the yield and selectivity of light olefins.

[0046] It should be noted that the present invention's approach of first conducting a first catalytic cracking reaction in the ascending reactor 1 and then conducting a second catalytic cracking reaction in the descending reactor 2 has broader applicability, enabling successful catalytic cracking reactions with both feedstocks containing a high proportion of light components and feedstocks containing a high proportion of heavy components. Because the feedstock first enters the ascending reactor 1 and moves upward before entering the descending reactor 2, even the heavy components are able to effectively contact the catalyst. The entire catalytic cracking process avoids the accumulation of heavy components, thereby enabling successful catalytic cracking reactions and achieving high yields and selectivities of light olefins.

[0047] As a first embodiment of the first aspect of the present invention, Figure 1 As shown, the oil agent outlet of the upward reactor 1 and the oil agent inlet of the downward reactor 2 are connected through the oil agent delivery pipe 3; the second catalyst output pipe 52 is connected to the first stripper and the first regenerator; the first catalyst delivery pipe 12 and the second catalyst delivery pipe 21 are respectively connected to the catalyst outlet of the first regenerator.

[0048] As a first embodiment of the second aspect of the present invention, the upward reactor and the downward reactor are directly connected through an oil agent delivery pipe, and the first oil agent mixture containing the first reaction oil gas is directly delivered to the downward reactor through the oil agent delivery pipe, so that the first reaction oil gas and the second catalyst contact in the downward reactor to carry out the second catalytic cracking reaction.

[0049] According to a first embodiment of the second aspect of the present invention, the method further comprises: stripping and regenerating the second spent catalyst; the first catalyst and the second catalyst are each independently selected from a regenerated catalyst and / or a cooled regenerated catalyst.

[0050] It should be noted that the system of the first embodiment of the first aspect of the present invention is applicable to the method of the first embodiment of the second aspect of the present invention. The first oil mixture obtained by the reaction in the upward reactor 1 enters the downward reactor 2 through the oil delivery pipe 3, so that the first reaction oil gas and the second catalyst contact in the downward reactor to carry out a second catalytic cracking reaction to obtain a second oil mixture. The second catalyst to be regenerated separated from the second oil mixture by the oil separation device 5 is transported to the first stripper through the second catalyst output pipe 52 for stripping, and then enters the first regenerator for regeneration to obtain a regenerated catalyst. The obtained regenerated catalyst can be transported to the upward reactor 1 and the downward reactor 2 respectively through the first catalyst delivery pipe 12 and the second catalyst delivery pipe 21 to be recycled as the first catalyst and the second catalyst respectively. This embodiment can form a good self-circulating system.

[0051] As a second embodiment of the first aspect of the present invention, Figure 2 As shown, the system is further provided with a gas-solid quick separation device 13, the inlet of the gas-solid quick separation device 13 is connected to the oil agent outlet of the upward reactor 1, and the gas outlet of the gas-solid quick separation device 13 is connected to the oil agent inlet of the downward reactor 2 (which can be connected through the oil agent delivery pipe 3); preferably, the system is further provided with a second stripper 4 and a second regenerator, the second stripper 4 is provided with a stripping steam input pipe 41, a first catalyst to be regenerated output pipe 42 and a stripping oil and gas delivery pipe 43, the solid outlet of the gas-solid quick separation device 13 is connected to the solid inlet of the second stripper 4, the outlet of the first catalyst to be regenerated output pipe 42 is connected to the inlet of the second regenerator, and the stripping oil and gas delivery pipe 43 is connected to the upper part of the downward reactor 2.

[0052] As a second embodiment of the second aspect of the present invention, a gas-solid quick separation device is provided between the upward reactor and the downward reactor, and the first oil agent mixture is separated into the first reaction oil and gas and the first catalyst to be generated through the gas-solid quick separation device; the first reaction oil and gas is transported to the downward reactor so that the first reaction oil and gas contact the second catalyst in the downward reactor to carry out the second catalytic cracking reaction.

[0053] According to a second embodiment of the second aspect of the present invention, the method further comprises: stripping and regenerating the first spent catalyst separated by the gas-solid quick separation device.

[0054] It should be noted that the system of the second embodiment of the first aspect of the present invention is applicable to the method of the second embodiment of the second aspect of the present invention. The gas-solid quick separation device 13 can be any device capable of separating oil, gas, and catalyst, such as a cyclone quick separation device. The first oil mixture obtained by the reaction in the ascending reactor 1 is directly fed into the gas-solid quick separation device 13 for separation, yielding the first reaction oil and gas and the first regenerated catalyst. The resulting first reaction oil and gas enter the descending reactor 2 through the gas outlet of the gas-solid quick separation device 13 to continue the catalytic cracking reaction. The resulting first regenerated catalyst enters the second stripper 4 through the solid outlet of the gas-solid quick separation device 13 for stripping to remove hydrocarbons adsorbed on the catalyst. The stripped oil and gas are then transported to the descending reactor 2 via the stripping oil and gas delivery pipe 43. The first reaction oil and gas also enter the descending reactor 2, where they contact the second catalyst and undergo catalytic cracking at a higher reaction temperature. The stripped catalyst enters the second regenerator through the first regenerated catalyst outlet pipe 42 for regeneration, yielding regenerated catalyst. The regenerated catalyst can be returned to the system for recycling.

[0055] It should be noted that in the first catalytic cracking reaction, heavy components such as colloids and asphaltenes in the feedstock oil are preferentially adsorbed on the active centers of the catalyst, but these colloids and asphaltenes often cover the active centers in the form of coke, resulting in reduced catalyst activity and reduced selectivity for cracking of other hydrocarbons. This embodiment first pre-cracks the hydrocarbons in the upward reactor 1 to generate a large amount of olefin-rich intermediate components, namely the first reaction oil and gas, and separates or replaces the deactivated catalyst, namely the first catalyst to be regenerated, through the gas-solid quick separation device 13. Then, in the downward reactor 2, a higher reaction temperature, a shorter residence time and the introduction of a second catalyst can be used to further convert the intermediate components, namely the first reaction oil and gas, into light olefins with high selectivity. This embodiment can further make the reaction temperature and catalyst activity more closely match the cracking performance of different hydrocarbon molecules in the catalytic cracking process, and further increase the yield and selectivity of light olefins.

[0056] According to a second embodiment of the second aspect of the present invention, the residence time of the first oil mixture in the gas-solid fast separation device is less than 0.05s; preferably, the residence time of the first oil mixture in the gas-solid fast separation device is less than 0.03s.

[0057] It should be noted that, under the above-mentioned residence time, the first oil mixture can undergo good gas-solid separation in the gas-solid quick separation equipment to obtain the first reaction oil and gas and the first catalyst to be generated. The first reaction oil and gas can quickly enter the downward reactor 2 to continue the catalytic cracking reaction.

[0058] According to a second embodiment of the first aspect of the present invention, the second catalyst output pipe 52 to be regenerated is connected to a third stripper and a third regenerator; the inlet of the first catalyst delivery pipe 12 is respectively connected to the catalyst outlet of the second regenerator, the catalyst outlet of the third regenerator and the second catalyst output pipe 52 to be regenerated; the inlet of the second catalyst delivery pipe 21 is respectively connected to the catalyst outlet of the second regenerator and the catalyst outlet of the third regenerator.

[0059] According to a second embodiment of the second aspect of the present invention, the second spent catalyst is stripped and regenerated; the second catalyst is a regenerated catalyst and / or a cooled regenerated catalyst.

[0060] According to a second embodiment of the second aspect of the present invention, the first catalyst is selected from a combination of one or more of a regenerated catalyst, a cooled regenerated catalyst and the second catalyst to be regenerated; preferably, the first catalyst is a combination of the regenerated catalyst and the second catalyst to be regenerated; further preferably, the first catalyst is the second catalyst to be regenerated.

[0061] It should be noted that the second regenerated catalyst can be transported to the third stripper via the second regenerated catalyst output pipe 52 for stripping, and then enter the third regenerator for char regeneration to obtain a regenerated catalyst. The obtained regenerated catalyst can be returned to the system for recycling. The first catalyst can be selected from a combination of one or more of the regenerated catalyst obtained from the second regenerator, the regenerated catalyst obtained from the third regenerator, and the second regenerated catalyst. The second catalyst can be selected from the regenerated catalyst obtained from the second regenerator and / or the regenerated catalyst obtained from the third regenerator.

[0062] It should be noted that the second regenerator and the third regenerator can be the same regenerator or different regenerators. The method and system of this embodiment can form a good self-circulating system.

[0063] It should be noted that the use of the second catalyst to be regenerated as the first catalyst is a preferred embodiment. The first catalyst is in contact with the crude oil for catalytic cracking. During the first catalytic cracking reaction, many active sites in the first catalyst are covered by coke formed by heavy components, so the first catalyst to be regenerated is seriously deactivated; however, the first reaction oil and gas entering the downward reactor 2 is olefin-rich oil and gas with a significantly reduced content of heavy components, and the second catalyst rarely has the above-mentioned coke coverage. Therefore, the second catalyst to be regenerated is a catalyst that still maintains a certain good activity and has a certain temperature. Studies have found that using the second catalyst to be regenerated as the first catalyst can further enable the catalytic cracking reaction to proceed better, and directly using the second catalyst to be regenerated as the first catalyst enables the entire system or method to circulate better.

[0064] According to the first embodiment or the second embodiment of the first aspect of the present invention, the upward reactor is a single or composite reactor of a riser reactor of equal or variable diameter and a fast bed reactor, and the downward reactor is a straight tube of equal or variable diameter.

[0065] It should be noted that the system of the present invention has an ingenious design and a simple assembly process, and has the potential for large-scale production.

[0066] According to the first embodiment or the second embodiment of the second aspect of the present invention, in step (1), the outlet temperature of the upward reactor is 500-650°C, and the oil and gas residence time is 0.5-5s; the weight ratio of the first catalyst to the feedstock oil is (1-50):1; preferably, the outlet temperature of the upward reactor is 530-600°C, and the oil and gas residence time is 1.0-2.0s; the weight ratio of the first catalyst to the feedstock oil is (10-30):1.

[0067] It should be noted that the outlet temperature of the upward reactor can be controlled by the temperature of the introduced first catalyst and / or can be controlled by externally heating the upward reactor.

[0068] According to the first embodiment or the second embodiment of the second aspect of the present invention, in step (2), the outlet temperature of the down-type reactor is 550-700°C, and the oil and gas residence time is 0.1-2s; the weight ratio of the second catalyst to the feed oil is (5-50):1; preferably, the outlet temperature of the down-type reactor is 560-650°C, and the oil and gas residence time is 0.5-1.0s; the weight ratio of the second catalyst to the feed oil is (10-30):1.

[0069] It should be noted that the outlet temperature of the down-type reactor can be controlled by the temperature of the introduced second catalyst and / or by externally heating the down-type reactor.

[0070] According to the first embodiment or the second embodiment of the second aspect of the present invention, the feedstock oil is selected from a combination of one or more of crude oil, atmospheric wax oil, vacuum wax oil, atmospheric residue oil, vacuum residue oil, deasphalted oil, hydrogenated heavy oil and coker wax oil; or is selected from a combination of partial fractions or full fractions of one or more of coal liquefaction oil, oil sands oil, shale oil, synthetic oil, and animal and plant oils and fats.

[0071] It should be noted that crude oil, atmospheric gas oil, vacuum gas oil, etc. are petroleum hydrocarbons, while coal liquefaction oil, oil sands oil, shale oil, etc. are mineral oils. The method of producing light olefins from hydrocarbon oil feedstocks of the present invention has wide applicability, can effectively catalytically crack a variety of feedstock oils to obtain high light olefin yields and selectivities, and does not require pre-separation of the feedstock oils. The method is simple and energy-efficient.

[0072] The present invention is further described in detail below by way of examples, but the present invention is not limited thereto.

[0073] The catalytic cracking catalyst used in the following examples and comparative examples was produced by the Qilu Branch of Sinopec Catalyst Co., Ltd., under the trade designation EP-3B. This catalyst contains a ZSP molecular sieve with an average pore size of less than 0.7 nanometers and an ultrastable Y-type molecular sieve. Prior to use, the catalyst was hydrothermally aged at 800°C with saturated steam for 17 hours. The main physicochemical properties of the catalyst are shown in Table 1. The properties of the feedstock oils used in the examples and comparative examples are listed in Table 2.

[0074] In the following examples and comparative examples, the calculation method and the like are described as follows:

[0075] The product distribution values ​​of dry gas, liquefied gas and gasoline in the table represent mass fractions; among them, the dry gas yield is the sum of the mass fractions of H2, CH4 and C2 hydrocarbons in the product; the liquefied gas yield is the sum of the mass fractions of C3 and C4 hydrocarbons in the product; the gasoline yield is the yield of liquids with a boiling point less than 221°C in the product; the diesel yield is the yield of liquids with a boiling point of 221°C to 331°C in the product; and the slurry oil yield is the yield of liquids with a boiling point greater than 331°C in the product.

[0076] Conversion rate (%) = 100% - diesel yield - slurry yield;

[0077] Triene yield (%) = ethylene yield + propylene yield + butene yield;

[0078] Triene selectivity = triene yield ÷ conversion rate.

[0079] Table 1

[0080]

[0081] Table 2

[0082]

[0083]

[0084] Example 1

[0085] The experiment was carried out using a modified medium-sized unit with continuous reaction-regeneration operation, such as Figure 1 As shown in the figure, in this medium-sized unit, the ascending reactor 1 is a riser reactor with an inner diameter of 36 mm and a length of 4600 mm, while the descending reactor 2 is a straight tube with an inner diameter of 30 mm and a length of 1200 mm. The ascending reactor 1 and the descending reactor 2 are directly connected by an oil transfer pipe.

[0086] The 670°C high-temperature regenerated catalyst is introduced to the bottom of the riser reactor via the regeneration inclined tube and the first catalyst delivery tube 12. The preheated crude oil, after being atomized with steam, enters the riser reactor through the crude oil feed nozzle 11, where it contacts the hot regenerated catalyst for a catalytic cracking reaction. The reacted crude oil enters the top of the descender reactor, where it contacts the 670°C high-temperature regenerated catalyst introduced via the second catalyst delivery tube 21 to continue the cracking reaction. The reacted crude oil is then introduced into the crude oil separation system (i.e., crude oil separation device 5). The separated reaction oil gas is introduced into the product separation system (i.e., oil-gas separation device) for separation into gaseous and liquid products. The separated catalyst is also stripped and then introduced into the regenerator for char regeneration. The regenerated catalyst is returned to the reactor via the regeneration inclined tube (entering the first catalyst delivery tube 12 and the second catalyst delivery tube 21) for recycling. The medium-sized unit uses electric heating to maintain the temperature of the reaction-regeneration system.

[0087] The main operating conditions and results are listed in Table 3.

[0088] Comparative Example 1

[0089] Comparative Example Description: The test was carried out with the same raw materials, catalyst, apparatus and reaction conditions as in Example 1, except that the outlet temperature of the down-type reactor was lower than the outlet temperature of the riser reactor.

[0090] The main operating conditions and results are listed in Table 3.

[0091] Table 3

[0092] Item Example 1 Comparative Example 1 Riser reactor outlet temperature / °C 550 590 Riser reactor catalyst to oil mass ratio 10 10 Riser reactor reaction time / s 1.2 1.2 Downer reactor outlet temperature / °C 590 550 Downer reactor catalyst to oil mass ratio 15 10 Downer reactor reaction time / s 0.8 0.8 Product distribution / % Product distribution / % Dry gas 11.14 9.77 LPG 47.25 44.38 Gasoline 25.30 27.93 Diesel 7.25 7.83 Slurry oil 3.67 4.15 Coke 5.39 5.94 Total 100.00 100.00 Conversion / % 89.08 88.02 Ethylene yield / % 8.10 6.62 Propylene yield / % 21.44 19.04 Butylenes yield / % 17.52 17.14 Trienes yield / % 47.06 42.80 Trienes selectivity 0.528 0.486

[0093] Note: The reaction time of the riser reactor and the reaction time of the down-type reactor refer to the oil and gas residence time in the reactor respectively.

[0094] As can be seen from the data in Table 3, the method and system for producing light olefins using the hydrocarbon oil feedstock provided by the present invention in Example 1 not only has a high triene yield but also a high triene selectivity.

[0095] Example 2

[0096] The experiment was carried out using a modified medium-sized unit with continuous reaction-regeneration operation, such as Figure 2 In this medium-sized device, the ascending reactor 1 is a riser reactor with an inner diameter of 36 mm and a length of 4600 mm. The descending reactor 2 is a straight tube with an inner diameter of 30 mm and a length of 1200 mm. A cyclonic rapid separation device (i.e., gas-solid rapid separation device 13) is used between the ascending reactor 1 and the descending reactor 2 to separate the oil solution.

[0097] The high-temperature regenerated catalyst at 670°C is introduced into the bottom of the riser reactor through the regeneration inclined pipe and the first catalyst delivery pipe 12. The preheated raw oil is atomized by water vapor and enters the riser reactor through the raw oil feed nozzle to contact with the hot regenerated catalyst for catalytic cracking reaction. The reacted oil agent is separated into reaction oil gas and catalyst to be regenerated through cyclone fast separation (i.e., gas-solid fast separation equipment 13). The residence time of the reacted oil agent in the cyclone fast separation is 0.03s. The catalyst to be regenerated is introduced into the regenerator for char regeneration after stripping.

[0098] The reaction oil and gas immediately enter the top of the descending reactor, where they come into contact with the 670°C high-temperature regenerated catalyst introduced through the second catalyst delivery pipe 21 to continue the cracking reaction. The reacted oil is then introduced into the oil separation system (i.e., the oil separation device 5). The separated reaction oil and gas are then introduced into the product separation system (i.e., the oil-gas separation device) for separation into gaseous and liquid products. The separated catalyst is also stripped and then introduced into the regenerator for char regeneration. The regenerated catalyst is returned to the reactor through the regeneration inclined pipe (entering the first catalyst delivery pipe 12 and the second catalyst delivery pipe 21) for recycling. The medium-sized unit uses electric heating to maintain the temperature of the reaction-regeneration system.

[0099] The main operating conditions and results are listed in Table 4.

[0100] Example 3

[0101] Catalytic cracking was performed to produce light olefins using the same raw materials, catalysts, apparatus, and reaction conditions as in Example 2, except that the first catalyst used in the riser reactor was entirely separated from the reaction in the descending reactor (second spent catalyst). The temperature of the second spent catalyst entering the riser reactor was 620°C, the outlet temperature of the descending reactor was 620°C, and the catalyst-to-oil mass ratio in the descending reactor was 14.

[0102] The main operating conditions and results are listed in Table 4.

[0103] Comparative Example 2

[0104] Catalytic cracking was carried out to produce light olefins using the same raw materials, catalysts, equipment and reaction conditions as in Example 2, except that the outlet temperature of the down-type reactor was lower than the outlet temperature of the riser reactor.

[0105] The main operating conditions and results are listed in Table 4.

[0106] Table 4

[0107] Item Example 2 Example 3 Comparative Example 2 Riser reactor outlet temperature / °C 550 550 590 Riser reactor catalyst to oil mass ratio 10 14 10 Riser reactor reaction time / s 1.2 1.2 1.2 Downer reactor outlet temperature / °C 590 620 550 Downer reactor catalyst to oil mass ratio 10 14 10 Downer reactor reaction time / s 0.8 0.8 0.8 Product distribution / % Product distribution / % Product distribution / % Dry gas 10.90 9.52 11.52 LPG 46.91 48.21 45.37 Gasoline 21.43 21.80 21.66 Diesel 7.68 7.94 7.94 Slurry oil 3.14 3.25 3.27 Coke 9.94 9.28 10.24 Total 100.00 100.00 100.00 Conversion / % 89.18 88.81 88.79 Ethylene yield / % 7.78 7.22 7.33 Propylene yield / % 23.10 25.34 21.14 Butylenes yield / % 17.21 18.24 16.87 Trienes yield / % 48.09 50.80 45.34 Trienes selectivity 0.539 0.572 0.511

[0108] Note: The reaction time of the riser reactor and the reaction time of the down-type reactor refer to the oil and gas residence time in the reactor respectively.

[0109] As can be seen from the data in Table 4, Examples 2 and 3 use the method and system for producing light olefins from hydrocarbon oil feedstocks provided by the present invention, which not only achieves high triene yields but also high triene selectivity. In particular, in Example 3, the first catalyst used in the riser reactor is entirely the catalyst (second spent catalyst) obtained by separation after the reaction in the descending reactor, which achieves higher triene yields and triene selectivity.

[0110] In the description of this application, it should be noted that the terms "upper", "lower", "inside", "outside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on this application.

[0111] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0112] The present application has been described above in conjunction with preferred embodiments, but these embodiments are merely exemplary and serve only as an illustrative example. On this basis, various replacements and improvements can be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A method for producing light olefins from hydrocarbon oil feedstock, wherein: The method includes: (1) contacting the feedstock oil with a first catalyst in an ascending reactor to perform a first catalytic cracking reaction to obtain a first oil-agent mixture, wherein the first oil-agent mixture comprises a first reaction oil gas and a first catalyst to be generated; (2) contacting the first reaction oil and gas with a second catalyst in a down-flow reactor to perform a second catalytic cracking reaction to obtain a second oil mixture; (3) separating the second oil mixture to obtain a second reaction oil gas and a second spent catalyst, and separating the second reaction oil gas to obtain light olefins; wherein the outlet temperature of the down-flow reactor is 10-100°C higher than the outlet temperature of the up-flow reactor, and a gas-solid quick separation device is provided between the up-flow reactor and the down-flow reactor, and the first oil mixture is separated into the first reaction oil gas and the first catalyst to be generated via the gas-solid quick separation device; the first reaction oil gas is transported to the down-flow reactor so that the first reaction oil gas contacts the second catalyst in the down-flow reactor to perform the second catalytic cracking reaction, wherein the residence time of the first oil mixture in the gas-solid quick separation device is less than 0.05s, and The first catalyst used in the upward reactor is entirely the second spent catalyst.

2. The method according to claim 1, wherein The method further comprises: stripping and regenerating the first spent catalyst separated by the gas-solid quick separation device; stripping and regenerating the second spent catalyst; The second catalyst is a regenerated catalyst and / or a cooled regenerated catalyst.

3. The method according to claim 1, wherein The residence time of the first oil agent mixture in the gas-solid quick separation equipment is less than 0.03s.

4. The method according to claim 1, wherein In step (1), the outlet temperature of the upward reactor is 500-650° C., the oil and gas residence time is 0.5-5 s; and the weight ratio of the first catalyst to the feedstock oil is (1-50):

1.

5. The method according to claim 4, wherein The outlet temperature of the upward reactor is 530-600° C., and the oil and gas residence time is 1.0-2.0 s. The weight ratio of the first catalyst to the feedstock oil is (10-30):

1.

6. The method according to claim 1, wherein In step (2), the outlet temperature of the downward reactor is 550-700° C., the oil and gas residence time is 0.1-2 s; and the weight ratio of the second catalyst to the feedstock oil is (5-50):

1.

7. The method according to claim 6, wherein: The outlet temperature of the downward reactor is 560-650° C., and the oil and gas residence time is 0.5-1.0 s. The weight ratio of the second catalyst to the feedstock oil is (10-30):

1.

8. The method according to claim 1, wherein The raw oil is selected from one or more of crude oil, atmospheric wax oil, vacuum wax oil, atmospheric residue oil, vacuum residue oil, deasphalted oil, hydrogenated heavy oil and coker wax oil; or is selected from partial fractions or full fractions of one or more of oil sands oil, shale oil, synthetic oil, animal and plant oils and fats.

9. The method according to claim 1, wherein The raw oil is coal liquefaction oil.

10. The method according to claim 1, wherein The upward reactor is a single or composite reactor of a riser reactor with a constant or variable diameter and a fast bed reactor, and the downward reactor is a straight tube with a constant or variable diameter.

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