Multiple dense phase risers for maximizing light olefin yields in naphtha catalytic cracking

Abstract

A system and method for producing light olefins by catalytic cracking of naphtha is disclosed. A naphtha feed stream and a lift gas stream are fed to a plurality of dense phase riser reactors, each of which operates at a high solid volume fraction, a high superficial velocity, and minimal backmixing. The effluent stream from each dense phase riser reactor is further separated in a secondary reactor to form a gaseous product stream and a catalyst stream. The catalyst stream is stripped to remove hydrocarbons adsorbed on the catalyst particles. The stripped catalyst is regenerated in a regenerator.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 883,059, filed on August 5, 2019, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention generally relates to systems and methods for producing light olefins. More specifically, the present invention relates to systems and methods for producing light olefins by catalytic cracking of naphtha in a dense phase riser reactor. Background Art

[0004] Light olefins (C2 to C4 olefins) are building blocks for many chemical processes. Light olefins are used to produce polyethylene, polypropylene, ethylene oxide, vinyl chloride, propylene oxide and acrylic acid, which in turn are used in various industries, such as plastic processing, construction, textiles and the automotive industry. Generally, light olefins are produced by steam cracking naphtha and dehydrogenation of paraffins.

[0005] Over the past several decades, the demand for light olefins has been increasing. For one of the conventional methods for producing light olefins, the overall efficiency is relatively low because the overall selectivity of naphtha to light olefins is limited. Therefore, the steam cracking process produces a large amount of hydrocarbons, which are recycled to the steam cracking unit. Since the hydrocarbons must be hydrogenated before being recycled back to the steam cracking unit, the large amount of hydrocarbons for recycling will require a large amount of hydrogen and energy in the hydrogenation process, resulting in high production costs.

[0006] Another method for producing light olefins includes catalytic cracking of naphtha in a conventional fluidized bed reactor. However, due to the back mixing in the fluidized bed reactor, the yield of light olefins can be relatively low. And, due to the limitation of superficial gas velocity in the fluidized bed, the conventional fluidized bed reactor of catalytic cracking is usually operated under low average solid volume fraction and low gas-solid contact efficiency. Therefore, due to the production cost of thermal cracking and increased light olefins, conventional methods often cause high methane generation. In general, although there is a method for producing light olefins, in view of at least the above-mentioned shortcomings of these methods, there is still a demand for improvement in this field. Summary of the invention

[0007] A solution to at least some of the above-mentioned problems associated with a method for producing light olefins using naphtha as a feed material has been found. The solution is a method for producing light olefins, the method comprising using a plurality of dense phase riser reactors to catalytically crack naphtha. The superficial gas velocity in each of the dense phase riser reactors is significantly higher than in conventional methods. This is at least conducive to providing a high solid volume fraction in the dense phase riser reactor, thereby reducing the occurrence of thermal cracking of naphtha. In addition, the lifting gas used in the dense phase riser reactor does not contain steam. Therefore, a zeolite-based catalyst with a higher efficiency than a non-zeolite-based catalyst can be used and will not be dealuminated by steam. In addition, the method limits backmixing in the dense phase riser reactor, characterized in that a wide residence time distribution (RTD) with a relative variance of less than 0.25 is obtained, resulting in an increase in the ratio of olefins to aromatic compounds in the effluent from each of the dense phase riser reactors. Therefore, the method of the present invention provides a technical solution to at least some of the problems associated with the above-mentioned currently available methods for producing light olefins.

[0008] Embodiments of the present invention include methods for producing light olefins. The method includes contacting naphtha with catalyst particles in a plurality of dense phase riser reactors under reaction conditions sufficient to produce a first product comprising one or more olefins. The reaction conditions include a solid volume fraction of 0.06 to 0.12 in the dense phase riser reactor. The method includes flowing a mixture of the first product, the catalyst particles, and unreacted naphtha to a cyclone separator system disposed in a secondary reactor, wherein the secondary reactor is stacked on top of a catalyst regenerator.

[0009] Embodiments of the present invention include methods for producing light olefins. The method includes contacting naphtha with catalyst particles in a plurality of dense phase riser reactors under reaction conditions sufficient to produce a first product comprising one or more olefins. The reaction conditions include a solid volume fraction of 0.06 to 0.12 in the dense phase riser reactor. The method includes flowing a mixture of the first product, catalyst particles, and unreacted naphtha from one or more of the dense phase riser reactors to a cyclone separator system disposed in a secondary reactor, wherein the secondary reactor is stacked above a catalyst regenerator. The method includes separating the first product from the catalyst particles in a cyclone separator system. The method includes stripping hydrocarbon vapor from the catalyst particles in a stripper disposed in the regenerator to produce stripped catalyst particles. The method includes regenerating the stripped catalyst particles in the regenerator. The method further includes flowing the regenerated catalyst particles to one or more of the dense phase riser reactors.

[0010] Embodiments of the present invention include a reaction unit for producing olefins. The reaction unit includes a plurality of dense phase riser reactors. Each of the dense phase riser reactors includes a shell, a feed inlet disposed in the lower half of the shell and suitable for receiving feed materials into the shell, a lift gas inlet disposed in the lower half of the shell and suitable for receiving lift gas into the shell, a catalyst inlet disposed in the lower half of the shell and suitable for receiving catalyst into the shell, and an outlet disposed in the upper half of the shell and suitable for releasing the effluent of the dense phase riser from the shell. The reaction unit further includes a secondary reactor in fluid communication with each of the outlets of the dense phase riser reactor. The secondary reactor includes one or more cyclone separators, and the one or more cyclone separators are suitable for separating the effluent of each dense phase riser reactor to form a gaseous stream containing a gaseous product and a solid stream containing a catalyst. The reaction unit further includes a regenerator in fluid communication with the secondary reactor, the regenerator being suitable for receiving a solid stream from the secondary reactor and regenerating the catalyst of the solid stream. The regenerator is in fluid communication with the catalyst inlet of each of the dense phase riser reactors.

[0011] Included below are definitions of various terms and phrases used throughout this specification.

[0012] The term "about" or "approximately" is defined as close to, as understood by those of ordinary skill in the art. In a non-limiting embodiment, the term is defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0013] The terms "wt. %, "vol. %" or "mole %" refer to the weight percent, volume percent or mole percent of a component based on the total weight, total volume or total number of moles of the material including the component, respectively. In a non-limiting example, 10 moles of a component out of 100 moles of a material is 10 mol.% of the component.

[0014] The term "substantially" and variations thereof are defined to include ranges within 10%, within 5%, within 1% or within 0.5%.

[0015] The terms "inhibiting" or "reducing" or "preventing" or "avoiding" or any variation of these terms, when used in the claims and / or specification, include any measurable reduction or complete inhibition to achieve a desired result.

[0016] The term "effective" as used in the specification and / or claims means sufficient to achieve a desired, expected, or intended result.

[0017] The term "raffinate" as used in the specification and / or claims refers to the remaining portion of a product stream from which a target component has been removed.

[0018] The use of the word "a" or "an" when used with the terms "comprising," "including," "containing," or "having" in the claims or the specification may mean "one," but it also has the meanings of "one or more," "at least one," and "one or more than one."

[0019] The terms "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include"), or "containing" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended, and do not exclude additional, unrecited elements or method steps.

[0020] The methods of the present invention may "comprise," "consist essentially of," or "consist of" particular ingredients, components, compositions, etc. disclosed throughout this specification.

[0021] As used in the specification and / or claims, the term "mainly" refers to any one of greater than 50 wt.%, 50 mol.%, and 50 vol.%. For example, "mainly" may include 50.1 wt.% to 100 wt.% and all values ​​and ranges therebetween, 50.1 mol.% to 100 mol.% and all values ​​and ranges therebetween, or 50.1 vol.% to 100 vol.% and all values ​​and ranges therebetween.

[0022] Other objects, features and advantages of the present invention will become apparent from the following drawings, detailed descriptions and examples. However, it should be understood that, while indicating specific embodiments of the present invention, the drawings, detailed descriptions and examples are provided only by way of illustration and are not meant to be limiting. In addition, it is contemplated that changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. In other embodiments, features from a specific embodiment may be combined with features from other embodiments. For example, features from an embodiment may be combined with features from any other embodiment. In other embodiments, additional features may be added to the specific embodiments described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] For a more complete understanding, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0024] Figure 1 A schematic diagram showing a reaction unit for producing light olefins according to an embodiment of the present invention; and

[0025] Figure 2 A schematic flow chart of a method for producing light olefins according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] At present, light olefins (including ethylene, propylene, butenes) can be produced by steam cracking or catalytic cracking of naphtha. However, the total conversion rate of light olefins of steam cracked naphtha is relatively low. In addition, the production cost of steam cracked naphtha is high, because the steam cracking of naphtha produces a large amount of raffinates, which need to be hydrogenated before being recycled back to the steam cracking unit. Therefore, a large amount of raffinates cause high demand for hydrogen and energy in the hydrogenation process. The conventional method of catalytic cracking naphtha usually has a relatively low superficial gas velocity and a very high catalyst to oil ratio in the catalyst bed, which brings challenges to the pressure balance in the reactor. In addition, the catalytic cracking of conventional naphtha uses steam as a lifting gas, which prevents the use of zeolite-based catalysts (having high catalytic efficiency for light olefin production) in the reactor. The present invention provides solutions to at least some of these problems. The solution is based on a method for catalytic cracking naphtha included in a reaction unit (comprising a plurality of dense phase riser reactors). This method can keep high solid volume fraction and high superficial gas velocity in dense phase riser reactor, thereby reduces the thermal cracking of petroleum naphtha and increases the productivity of light olefins.In addition, this method limits the backmixing of catalyst and hydrocarbon in the dense phase riser reactor.Therefore, compared with conventional methods, the selectivity of light olefins is increased.In addition, this method can use the lifting gas that does not contain steam so that zeolite-based catalyst can be used in the reaction unit, thereby improves the production efficiency of light olefins.These and other non-limiting aspects of the present invention are discussed in detail in the following part.

[0027] A. System for catalytic cracking of naphtha to produce light olefins

[0028] In an embodiment of the present invention, a reaction unit for producing light olefins by catalytic cracking of naphtha comprises a plurality of dense phase riser reactors, a secondary reactor for gas-solid separation, and a regenerator. Figure 1, a schematic diagram of a reaction unit 100 is shown, which is configured to produce light olefins (e.g., C2 to C4 olefins), and has improved production efficiency and light olefin yield compared to conventional steam cracking or catalytic cracking methods. According to an embodiment of the present invention, reaction unit 100 includes multiple dense phase riser reactors (e.g., dense phase riser reactors 101 and 101 '). In an embodiment of the present invention, reaction unit 100 includes 2 to 4 dense phase riser reactors. Each dense phase riser reactor (e.g., dense phase riser reactor 101) can include a shell 102, a feed inlet 103, a lift gas inlet 104, a catalyst inlet 105, and an effluent outlet 106. In an embodiment of the present invention, each dense phase riser reactor 101 includes a fluidized bed reactor.

[0029] In an embodiment of the present invention, the shell 102 is made of carbon steel, refractory material or a combination thereof. The shell 102 is suitable for carrying the catalytic cracking of naphtha. According to an embodiment of the present invention, the feed inlet 103 can be arranged at the lower half of the shell 102 and is suitable for receiving the feed stream therein. In an embodiment of the present invention, the feed stream includes naphtha. In an embodiment of the present invention, the lifting gas inlet 104 is arranged at the lower half of the shell 102 and is suitable for receiving the lifting gas stream into the shell 102. In an embodiment of the present invention, the lifting gas inlet 104 can be arranged below the feed inlet 103. The lifting gas stream can include nitrogen, methane, any inert gas or a combination thereof. In an embodiment of the present invention, the catalyst inlet 105 is arranged at the lower half of the shell 102. The catalyst inlet 105 can be suitable for receiving catalyst particles into the shell 102. Non-limiting examples of catalyst particles can include zeolites. According to an embodiment of the present invention, the catalyst particles have a particle size in the range of 75 to 120 μm and all ranges and values ​​therebetween, including 75 to 78 μm, 78 to 81 μm, 81 to 84 μm, 84 to 87 μm, 87 to 90 μm, 90 to 93 μm, 93 to 96 μm, 96 to 99 μm, 99 to 102 μm, 102 to 105 μm, 105 to 108 μm, 108 to 111 μm, 111 to 114 μm, 114 to 117 μm and 117 to 120 μm. The catalyst particles have a particle size in the range of 1000 to 1700 kg / m 3 Density within the range and all ranges and values ​​therebetween, inclusive, 1000 to 1100 kg / m 3 1100 to 1200kg / m 3 1200 to 1300kg / m 3 1300 to 1400kg / m 3 1400 to 1500kg / m 3 1500 to 1600 kg / m3 , and 1600 to 1700kg / m 3 The fluidized bed in each dense phase riser reactor 101 may have a fluid pressure of 70 to 145 kg / m 3 The total bulk density within the range and all ranges and values ​​therebetween, inclusive, 70 to 75 kg / m 3 , 75 to 80 kg / m 3 , 80 to 85 kg / m 3 , 85 to 90 kg / m 3 , 90 to 95 kg / m 3 , 95 to 100 kg / m 3 100 to 105 kg / m 3 105 to 110 kg / m 3 110 to 115 kg / m 3 115 to 120 kg / m 3 120 to 125 kg / m 3 125 to 130 kg / m 3 130 to 135 kg / m 3 135 to 140 kg / m 3 and 140 to 145 kg / m 3 In an embodiment of the present invention, the catalyst inlet 105 may be disposed above the lift gas inlet 104. According to an embodiment of the present invention, the lift gas inlet 104 is disposed below the feed inlet 103 and the catalyst inlet 105.

[0030] In an embodiment of the present invention, each dense phase riser reactor 101 can be substantially cylindrical. Each dense phase riser reactor 101 can have a height to diameter ratio in the range of 8 to 27 and all ranges and values ​​therebetween, including the ranges of 8 to 9, 9 to 11, 11 to 13, 13 to 15, 15 to 17, 17 to 19, 19 to 21, 21 to 23, 23 to 25, and 25 to 27. In an embodiment of the present invention, each dense phase riser reactor 101 has an inner diameter in the range of 2.0 to 2.75 m and all ranges and values ​​therebetween. According to an embodiment of the present invention, each dense phase riser reactor 101 includes an outlet 106 (or outlet 106') that is fluidly connected to the secondary reactor 107 so that the effluent of each dense phase riser reactor 107 flows from the dense phase riser reactor 107 to the secondary reactor 107.

[0031] The effluent from each of the dense phase riser reactors 101 may include unreacted naphtha, light olefins, lifting gas, spent catalyst particles, and any other byproducts. The effluent from each dense phase riser reactor 101 may further include aromatic compounds. According to an embodiment of the present invention, the secondary reactor 107 is suitable for separating the effluent from each riser reactor 101 to form a product gas stream and a spent catalyst stream. The product gas stream may include light olefins, unreacted naphtha, aromatic compounds, lifting gas, byproducts, or a combination thereof. The spent catalyst stream may include spent catalyst particles, hydrocarbons adsorbed on the spent catalyst particles, lifting gas, or a combination thereof.

[0032] According to an embodiment of the present invention, the secondary reactor 107 includes a secondary reactor shell 108 and one or more cyclone separators 109, which are suitable for separating the effluent from each dense phase riser reactor 101 to form a spent catalyst stream containing spent catalyst particles and a product gas stream containing product gas from each dense phase riser reactor 101. In an embodiment of the present invention, each cyclone separator 109 in the secondary reactor 107 is a single-stage or multi-stage cyclone separator. Each cyclone separator 109 can be connected to a feed leg fluid. The feed leg is suitable for transferring catalyst particles from the cyclone separator to a dense phase bed near the bottom of the secondary reactor 107. In an embodiment of the present invention, the feed leg of each cyclone separator 109 is further connected to a splash plate and / or a drip valve fluid. The splash plate and / or the drip valve can be suitable for avoiding gas bypassing the feed leg of the cyclone separator.

[0033] In an embodiment of the present invention, the bottom end of the secondary reactor 107 may be in fluid communication with the regenerator 110 so that the spent catalyst stream flows from the secondary reactor 107 to the catalyst regenerator 110. In an embodiment of the present invention, the regenerator 110 is suitable for stripping hydrocarbons adsorbed on the spent catalyst particles and regenerating the spent catalyst after the stripping process. The regenerator 110 may be further suitable for separating flue gas from the catalyst. According to an embodiment of the present invention, the secondary reactor 107 is stacked on top of the regenerator 110 so that the spent catalyst particles can flow directly from the secondary reactor 107 to the regenerator 110 without any additional driving force other than gravity.

[0034] According to an embodiment of the present invention, the regenerator 110 includes a stripper 111, which is configured to strip hydrocarbons adsorbed on the spent catalyst particles. The stripper 111 may include a stripping gas injector 112, which is configured to release a stripping gas to contact the spent catalyst. Non-limiting examples of stripping gas may include nitrogen, methane, flue gas and combinations thereof. The stripper 111 may further include a stripper internal 113, which is configured to enhance the countercurrent contact between the downwardly flowing stream (emulsion phase) and the upwardly flowing bubble stream in the stripper 111. The stripper internal 113 may include a disc-shaped structure internal, a V-shaped structure internal, a packing internal, a subway grating internal or a combination thereof. The stripper internals 113 may further include a riser 114 adapted to transfer catalyst particles from the stripper 111 to the regenerator 110 and a slide valve adapted to control the flow rate of catalyst particles from the stripper 111 to the regenerator 110. In an embodiment of the present invention, the regenerator 110 further includes an air inlet 115, the air inlet 115 being in fluid communication with an air injector 116, the air injector 116 being disposed in the catalyst regeneration unit 112 so that air is supplied to the regenerator 110 through the air inlet 115 and the air injector 116. According to an embodiment of the present invention, the regenerator 110 further includes one or more cyclone separators (e.g., cyclone separator 118) adapted to separate flue gas from the catalyst. The flue gas may include flue gas generated during the catalyst regeneration process. According to an embodiment of the present invention, the regenerator 110 includes multiple catalyst outlets (for example, catalyst outlets 117 and 117'), each of which is fluidly connected to the catalyst inlet 105 (or catalyst inlet 105') of each dense phase riser reactor 101 (or dense phase riser reactor 101') so that the regenerated catalyst flows from the regenerator 110 to each dense phase riser reactor 101.

[0035] The dense phase riser reactors (e.g., dense phase riser reactors 101 and 101') can be operated in parallel. According to an embodiment of the present invention, each dense phase riser reactor includes an outlet in fluid communication with the cyclone separator system 109 of the secondary reactor 107 so that the effluent from each dense phase riser reactor flows into the cyclone separator system 109. For example, Figure 1As shown, the dense phase riser reactor 101 may include an outlet 106 in fluid communication with the cyclone separator system 109. The dense phase riser reactor 101 may include an outlet 106' in fluid communication with the cyclone separator system 109. According to an embodiment of the present invention, each dense phase riser reactor includes a catalyst inlet in fluid communication with the catalyst outlet so that the regenerated catalyst flows from the regenerator 110 to each dense phase riser reactor. For example, Figure 1 As shown, Figure 1 As shown, the dense phase riser reactor 101 may include a catalyst inlet 105 in fluid communication with a catalyst outlet 117 of the regenerator 110. The dense phase riser reactor 101′ may include a catalyst inlet 105′ in fluid communication with a catalyst outlet 117′ of the regenerator 110. Two or more dense phase riser reactors of the reaction unit 100 may be configured to share a secondary reactor 107 and a regenerator 110 to reduce capital expenditures and energy consumption compared to using one secondary reactor and one regenerator for each dense phase riser reactor. Although Figure 1 Two dense phase riser reactors are shown, but in embodiments of the present invention, the reaction unit 100 may include three or more dense phase riser reactors operating together with a set of secondary reactors 107 and regenerators 110.

[0036] B. Process for producing aromatic compounds and olefins

[0037] A method for producing light olefins by catalytic cracking of naphtha has been discovered. Compared to conventional methods of catalytic cracking of naphtha, embodiments of the method can increase the solid volume fraction in the reaction unit and minimize the occurrence of thermal cracking of hydrocarbons. Therefore, compared to conventional methods, the method can significantly increase the efficiency of light olefin production. Figure 2 As shown, an embodiment of the present invention includes a method 200 for producing light olefins. The method 200 may be as follows: Figure 1 The reaction unit 100 is shown implemented.

[0038] According to an embodiment of the present invention, as shown in box 201, method 200 may include contacting naphtha with catalyst particles in multiple dense phase riser reactors under reaction conditions sufficient to produce a first product comprising one or more olefins. In an embodiment of the present invention, the contacting of box 201 includes injecting a lift gas via a lift gas inlet 104, naphtha via a feed inlet 103, and / or a catalyst via a catalyst inlet 105 into each dense phase riser reactor 101 so that the catalyst particles and naphtha contact each other, and the material in each dense phase riser reactor 101 moves upward. In an embodiment of the present invention, the naphtha in the contacting step of box 201 includes a hydrocarbon mixture having a final boiling point below 350°C. In an embodiment of the invention, the reaction conditions of box 201 may include a superficial gas velocity (SGV) in the fluidized bed of each riser reactor 101 greater than 6.5 m / s and preferably 12 to 21 m / s and all ranges and values ​​therebetween, including ranges of 12 to 13 m / s, 13 to 14 m / s, 14 to 15 m / s, 15 to 16 m / s, 16 to 17 m / s, 17 to 18 m / s, 18 to 19 m / s, 19 to 20 m / s, and 20 to 21 m / s. According to an embodiment of the present invention, the reaction conditions of block 201 include a solid volume fraction (SVF) of the fluidized catalyst bed of each dense phase riser reactor in the range of 0.06 to 0.12 and all ranges and values ​​therebetween, including the ranges of 0.06 to 0.07, 0.07 to 0.08, 0.08 to 0.09, 0.09 to 0.10, 0.10 to 0.11, and 0.11 to 0.12. The reaction conditions of block 201 may include a reaction temperature in the range of 670 to 730°C and all ranges and values ​​therebetween, including the ranges of 670 to 680°C, 680 to 690°C, 690 to 700°C, 700 to 710°C, 710 to 720°C, and 720 to 730°C. The reaction conditions of frame 201 may further include a reaction pressure of 1 to 3 bar and all ranges and values ​​therebetween, including a range of 1 to 1.5 bar, 1.5 to 2.0 bar, 2.0 to 2.5 bar, and 2.5 to 3.0 bar. The reaction conditions of frame 201 may further include an average residence time of 1 to 15 s and all ranges and values ​​therebetween (1 to 3 s, 3 to 6 s, 6 to 9 s, 9 to 12 s, and 12 to 15 s) in each dense phase riser reactor 101. The reaction conditions of frame 201 may further include an average residence time of 0.3 to 3 hr -1 Weight hourly space velocity within the range and all ranges and values ​​therebetween, including 0.3 to 0.6 hr -1 , 0.6 to 0.9 hr -1 , 0.9 to 1.2 hr -1 , 1.2 to 1.5 hours -1 , 1.5 to 1.8 hours -1, 1.8 to 2.1 hr -1 , 2.1 to 2.4 hours -1 , 2.4 to 2.7 hours -1 and 2.7 to 3.0hr -1 range.

[0039] According to an embodiment of the present invention, the catalyst of the dense phase riser reactor 101 comprises zeolite. The catalyst particles may have a mass fraction of 1000 to 1200 kg / m 3 Density within the range and all ranges and values ​​therebetween, inclusive, 1000 to 1010 kg / m 3 1010 to 1020 kg / m 3 1020 to 1030 kg / m 3 1030 to 1040 kg / m 3 1040 to 1050 kg / m 3 1050 to 1060 kg / m 3 , 1060 to 1070 kg / m 3 1070 to 1080 kg / m 3 1080 to 1090 kg / m 3 1090 to 1100 kg / m 3 1100 to 1110 kg / m 3 1110 to 1120 kg / m 3 1120 to 1130 kg / m 3 1130 to 1140 kg / m 3 1140 to 1150 kg / m 3 1150 to 1160 kg / m 3 1160 to 1170 kg / m 3 1170 to 1180 kg / m 3 1180 to 1190 kg / m 3 , and 1190 to 1200kg / m 3 Each dense phase riser reactor 101 of frame 201 can be in the range of 70 to 145 kg / m 3 The catalyst bed bulk density within the range and all ranges and values ​​therebetween (70 to 75 kg / m 3 , 75 to 80 kg / m 3 , 80 to 85 kg / m 3 , 85 to 90 kg / m 3 , 90 to 95 kg / m 3 , 95 to 100 kg / m 3 100 to 105 kg / m 3 105 to 110 kg / m3 110 to 115 kg / m 3 115 to 120 kg / m 3 120 to 125 kg / m 3 125 to 130 kg / m 3 130 to 135 kg / m 3 135 to 140 kg / m 3 and 140 to 145 kg / m 3 range).

[0040] According to an embodiment of the present invention, the lift gas and naphtha of the block 201 flow into each dense phase riser reactor 101 at a volume ratio of 0.4 to 0.8 and all ranges and values ​​therebetween, including the ranges of 0.4 to 0.5, 0.5 to 0.6, 0.6 to 0.7, and 0.7 to 0.8. Each dense phase riser reactor 101 may include a catalyst bed having a catalyst to oil ratio of 10 to 50 and all ranges and values ​​therebetween, including the ranges of 10 to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, and 45 to 50.

[0041] According to an embodiment of the present invention, as shown in block 202, the method 200 further includes flowing the effluent (including a mixture of the first product, catalyst particles and unreacted naphtha) from each dense phase riser reactor 101 to a cyclone separator system disposed in the secondary reactor 107. The effluent from each dense phase riser reactor 101 may further include a lifting gas. In an embodiment of the present invention, the flow of block 202 is driven by a lifting gas and / or feed. Non-limiting examples of lifting gases may include nitrogen, methane, any inert gas, steam, or a combination thereof.

[0042] According to an embodiment of the present invention, as shown in frame 203, method 200 further includes separating the first product from the catalyst particles in the cyclone separator system of the secondary reactor 107. In an embodiment of the present invention, the separation of frame 203 includes gas-solid separation to produce a gas product stream and a spent catalyst stream. According to an embodiment of the present invention, the gas product stream comprises a first product. In an embodiment of the present invention, the first product includes light olefins (C2 to C4 olefins), unreacted naphtha, aromatic compounds, lifting gas, by-products or a combination thereof. The first product may further include unreacted naphtha, lifting gas, aromatic compounds (including BTX), or a combination thereof. The first product may have a weight ratio of light olefins to BTX in the range of 2 to 4 and all ranges and values ​​therebetween, including 2 to 2.2, 2.2 to 2.4, 2.4 to 2.6, 2.6 to 2.8, 2.8 to 3.0, 3.0 to 3.2, 3.2 to 3.4, 3.4 to 3.6, 3.6 to 3.8, and 3.8 to 4.0. The yield of light olefins can be in the range of 45 to 48% and all ranges and values ​​therebetween, including the ranges of 45 to 46%, 46 to 47%, and 47 to 48%. The separation of block 203 can include passing the effluent of each dense phase riser reactor 101 through one or more cyclone separators of the separation secondary reactor 107. In an embodiment of the invention, the product gas stream comprises 45 to 48 wt.% light olefins.

[0043] According to an embodiment of the present invention, as shown in block 204, the method 200 includes stripping hydrocarbon vapor from catalyst particles in a stripper 111 disposed in the regenerator 110 to produce stripped catalyst particles. In an embodiment of the present invention, the hydrocarbon vapor is adsorbed on the catalyst particles prior to the stripping of block 204. In an embodiment of the present invention, the volume ratio of the stripping gas to the catalyst particles in block 204 is in the range of 0.02 to 0.65 and all ranges and values ​​therebetween, including the ranges of 0.02 to 0.09, 0.09 to 0.16, 0.16 to 0.23, 0.23 to 0.30, 0.30 to 0.37, 0.37 to 0.44, 0.44 to 0.51, 0.51 to 0.58, and 0.58 to 0.65.

[0044] According to an embodiment of the present invention, as shown in box 205, method 200 includes regenerating the stripped catalyst particles in regenerator 110. In an embodiment of the present invention, the catalyst particles of box 205 are regenerated in the presence of air. The regeneration of box 205 can be carried out at a regeneration temperature of 680 to 750°C and all ranges and values ​​therebetween (including the ranges of 680 to 690°C, 690 to 700°C, 700 to 710°C, 710 to 720°C, 720 to 730°C, 730 to 740°C, and 740 to 750°C). In an embodiment of the present invention, the regeneration of box 205 produces regenerated catalyst and flue gas. The flue gas can be separated from the regenerated catalyst in a cyclone separator 118. In an embodiment of the present invention, the regenerated catalyst flows to each dense phase riser reactor 101 via a catalyst outlet 117 (and / or 117') and a catalyst inlet 105 (and / or 105'). In an embodiment of the present invention, the catalytic cracking of process 200 has a yield of light olefins greater than 45%.

[0045] Although referenced Figure 2 The blocks of the present invention describe embodiments of the present invention, but it should be understood that the operation of the present invention is not limited to Figure 2 Therefore, embodiments of the present invention may be implemented in the same manner as Figure 2 The various blocks may be used in different orders to provide the functionality described herein.

[0046] The systems and methods described herein may also include various devices not shown and known to those skilled in the art of chemical processing, such as controllers, pipes, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and other devices that may not be shown.

[0047] As part of the present disclosure, specific examples are included below. This example is for illustrative purposes only and is not intended to limit the present invention. One of ordinary skill in the art will readily recognize that parameters that can be changed or modified to produce substantially the same results.

[0048] Example 1

[0049] (Production of light olefins by catalytic cracking)

[0050] The test of producing light olefins by catalytic cracking was carried out in the pilot reaction unit of the present invention. The dense phase riser reactor in the pilot reaction unit was operated at a high solid volume fraction and a minimum backmixing to maximize the light olefin yield. The feed components used in these tests are shown in Table 1.

[0051] Table 1. Raw material composition

[0052]

[0053] The reaction conditions of the reactive unit include a reaction temperature of 700°C, a catalyst regeneration temperature of 710°C, a reaction pressure of 1.50 atm, a contact time of 1.03 to 1.16 seconds, a catalyst to oil ratio of 30, and a reaction temperature of 1.9 hours. -1 Table 2 shows the yield results of each major product of the experiment.

[0054] Table 2 Results from pilot tests

[0055]

[0056] The composition of the product stream produced in the pilot plant is shown in Table 2. The results show that light olefins (including C2 to C4 olefins) have an overall yield of greater than 46%.

[0057] In the context of the present invention, at least the following 19 embodiments are described. Embodiment 1 is a method for producing light olefins. The method includes contacting naphtha with catalyst particles in a plurality of dense phase riser reactors under reaction conditions sufficient to produce a first product containing one or more olefins, wherein the reaction conditions include a solid volume fraction of 0.06 to 0.12 in each of the dense phase riser reactors. The method further includes flowing a mixture of the first product, catalyst particles and unreacted naphtha to a cyclone separator system disposed in a secondary reactor, wherein the secondary reactor is stacked on top of a catalyst regenerator. Embodiment 2 is a method as described in Embodiment 1, wherein the reaction conditions include a contact time between naphtha and catalyst particles in the range of 1 to 2 seconds. Embodiment 3 is a method as described in any one of Embodiments 1 or 2, wherein the first reaction conditions include a superficial gas velocity in the range of 12 to 21 m / s in the dense phase riser reactor. Embodiment 4 is a method as described in any one of Embodiments 1 to 3, wherein the reaction conditions further include a reaction temperature in the range of 670 to 600°C, a reaction pressure in the range of 1 to 3 bar and a reaction temperature in the range of 0.3 to 3hr -1. Embodiment 5 is a method as described in any one of embodiments 1 to 4, wherein the dense phase riser reactor is operated so that there is substantially no backmixing of materials in the dense phase riser reactor. Embodiment 6 is a method as described in any one of embodiments 1 to 5, wherein the dense phase riser reactor is operated so that the reaction kinetics in the dense phase riser reactor substantially follow those of a plug flow reactor. Embodiment 7 is a method as described in any one of embodiments 1 to 6, further comprising separating the first product from the catalyst particles in a cyclone separator system. The method further comprises stripping hydrocarbon vapor from the catalyst particles in a stripper disposed in a catalyst regenerator to produce stripped catalyst particles. The method further comprises regenerating the stripped catalyst particles in a catalyst regenerator. Embodiment 8 is a method as described in any one of embodiments 1 to 7, wherein the dense phase riser reactor is operated using a lifting gas selected from the group consisting of nitrogen, methane, steam, any inert gas, and combinations thereof. Embodiment 9 is a method as described in embodiment 8, wherein the lifting gas contains less than 10 wt.% steam. Embodiment 10 is a method as described in any one of embodiments 1 to 9, wherein the catalyst contains a zeolite-based catalyst. Embodiment 11 is a method as described in any one of embodiments 1 to 10, wherein the catalyst comprises particles with an average diameter in the range of 75 to 120 μm. Embodiment 12 is a method as described in any one of embodiments 1 to 11, wherein the catalyst has a mass fraction of 1000 to 1200 kg / m 3 Embodiment 13 is the method of any one of Embodiments 1 to 12, wherein each of the dense phase riser reactors comprises a fluidized bed having a catalyst to oil ratio of 10 to 50. Embodiment 14 is the method of any one of Embodiments 1 to 13, wherein the fluidized bed of each dense phase riser reactor has a catalyst to oil ratio of 70 to 145 kg / m 3 Embodiment 15 is the method of any one of embodiments 1 to 14, wherein the dense phase riser reactor is operated at a volume ratio of feed to lift gas in the range of 1.25 to 2.5.

[0058] Embodiment 16 is a reaction unit for producing aromatic compounds. The reaction unit includes a plurality of dense phase riser reactors, wherein each dense phase riser reactor includes a shell. The reaction unit further includes a feed inlet disposed at the lower half of the shell and adapted to receive feed material into the shell. The method further includes a lift gas inlet disposed at the bottom of the shell and adapted to receive lift gas into the shell. The reaction unit also includes a catalyst inlet disposed at the bottom of the shell and adapted to receive catalyst into the shell. In addition, the reaction unit includes an outlet disposed at the top of the shell and adapted to release the effluent of the dense phase riser from the shell. The reaction unit further includes a secondary reactor connected to the outlet fluid of each dense phase riser reactor, wherein the secondary reactor includes one or more cyclone separators, and the one or more cyclone separators are adapted to separate the effluent of each dense phase riser reactor to form a gas stream containing gaseous products and a solid stream containing catalyst. The reaction unit further includes a regenerator in fluid communication with the secondary reactor, the regenerator being suitable for receiving a solid stream from the secondary reactor and regenerating the catalyst of the solid stream, wherein the secondary reactor is stacked on top of the regenerator and the regenerator is in fluid communication with the catalyst inlet of each dense phase riser reactor. Embodiment 17 is a reaction unit as described in Embodiment 16, wherein the regenerator further includes a stripper, the stripper being suitable for stripping hydrocarbons adsorbed on catalyst particles of the solid stream using a stripping gas before catalyst regeneration. Embodiment 18 is a reaction unit as described in Embodiment 17, wherein the stripping gas contains nitrogen, methane, flue gas, or a combination thereof. Embodiment 19 is a reaction unit as described in any one of Embodiments 16 to 18, wherein the regenerator further includes one or more cyclone separators suitable for separating flue gas from the catalyst.

[0059] Although the embodiments and advantages thereof of the present application have been described in detail, it should be understood that various changes, substitutions and variations can be made here without departing from the spirit and scope of the embodiments defined by the appended claims. In addition, the scope of the present application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, material compositions, devices, methods and steps described in the specification. As will be readily understood by those of ordinary skill in the art from the above disclosure, processes, machines, manufactures, material compositions, devices, methods or steps that currently exist or will be developed later to perform functions substantially the same as the corresponding embodiments described herein or to achieve substantially the same results can be utilized. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, devices, methods or steps within their scope.

Claims

1. A method for producing light olefins, the method comprising: contacting the naphtha with catalyst particles in a plurality of dense phase riser reactors under reaction conditions sufficient to produce a first product comprising one or more olefins, wherein the reaction conditions include a solids volume fraction of 0.06 to 0.12 in each of the dense phase riser reactors; flowing the mixture of the first product, catalyst particles, and unreacted naphtha to a cyclone separator system disposed in a secondary reactor, wherein the secondary reactor is stacked on top of a catalyst regenerator; wherein the reaction conditions further include a reaction temperature in the range of 670 to 730°C and a reaction pressure in the range of 1 to 3 bar; wherein the dense phase riser reactor is operated such that there is substantially no backmixing of material in the dense phase riser reactor; and wherein the reaction conditions include a superficial gas velocity in the dense phase riser reactor in the range of 12 to 21 m / s.

2. The process of claim 1, wherein the reaction conditions include a contact time between the naphtha and the catalyst particles in the range of 1 to 2 seconds.

3. The method of any one of claims 1 and 2, wherein the reaction conditions further include a 0.3 to 3 hr -1 Weight hourly space velocity in the range.

4. The method according to any one of claims 1 and 2, further comprising: separating the first product from the catalyst particles in a cyclone separator system; stripping hydrocarbon vapors from catalyst particles in a stripper disposed in the catalyst regenerator to produce stripped catalyst particles; and The stripped catalyst particles are regenerated in a catalyst regenerator.

5. The process of any one of claims 1 and 2, wherein the dense phase riser reactor is operated using a lift gas selected from the group consisting of nitrogen, methane, steam, any inert gas, and combinations thereof.

6. The method of claim 5, wherein the lift gas contains less than 10 wt.% steam.

7. The process of any one of claims 1 and 2, wherein the catalyst comprises a zeolite-based catalyst.

8. The method of any one of claims 1 and 2, wherein the catalyst comprises particles having an average diameter in the range of 75 to 120 μm.

9. The process of any one of claims 1 and 2, wherein the catalyst has a mass fraction of 1000 to 1200 kg / m 3 of particle density.

10. The process of any one of claims 1 and 2, wherein each of the dense phase riser reactors comprises a fluidized bed having a catalyst to oil ratio of 10 to 50.

11. The process of claim 10, wherein the fluidized bed of each dense phase riser reactor has a fluid pressure of 70 to 145 kg / m 3 Bulk density within the range.

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