Hybrid circulating fluidized bed fluid catalytic cracking reactor for catalytic cracking of hydrocarbon feedstocks

Abstract

Systems and methods are presented for a hybrid circulating fluidized bed fluid catalytic cracking (CFB-FCC) system capable of accommodating and cracking feedstocks that are difficult for existing FCC designs to process, while also yielding a greater quantity of light olefins (e.g., ethylene, propylene and butenes) and / or aromatics. Such feedstocks contain C4+ hydrocarbons, have an API gravity ranging from 40-80 and a feed density ranging from 0.6 grams per cubic centimeter (g / cc) to 0.8 g / cc. The disclosed two-stage, hybrid CFB-FCC design involves the use of a low-velocity, dense-phase reactor pot for primary catalytic cracking reactions, in combination with the use of a higher-velocity, dilute-phase riser for secondary cracking reactions, with predetermined residence times and a high average catalyst solid fraction. Accordingly, the disclosed two-stage, hybrid FCC designs enable the production of high-value chemicals.

Description

24CHEM0016-WO-ORD1HYBRID CIRCULATING FLUIDIZED BED FLUID CATALYTIC CRACKING REACTOR FOR CATALYTIC CRACKING OF HYDROCARBON FEEDSTOCKSTECHNICAL FIELD

[0001] The present disclosure generally relates to systems and methods for fluid catalytic cracking. More specifically, the present disclosure relates to hybrid fluid catalytic cracker designs and operational parameters for catalytic cracking of hydrocarbon feedstocks, thereby to yield useful hydrocarbon products, such as olefins and aromatics, at a pilot scale or at a commercial scale.BACKGROUND

[0002] Petrochemical industries are predominantly based on ethylene, propylene, benzene, toluene, xylenes, butadiene, and butenes, which are often referred to as the basic building blocks for petrochemicals. Saudi Arabia has an abundance of liquid feedstock, liquid hydrocarbons, condensates and / or light crudes, which can be utilized as a feedstock to petrochemical industries. In addition, refineries are gradually shifting to minimize gasoline production from fluid catalytic cracking (FCC). Conventionally, most of these light feedstocks / crudes are processed via thermal or steam cracking to primarily be converted into smaller hydrocarbons / petrochemical products. However, thermal or steam cracking process is an energy intensive technology and requires high temperatures typically in the range of 400 degrees Celsius (°C) to 900 °C. Thermal cracking of liquid feedstocks produces a maximum propylene to ethylene weight ratio of about 0.5 and also a substantial amount of dry gas (e.g., about 10 weight percent (wt. %) to about 20 wt. %). As an alternative, catalytic cracking can be performed at a lower reaction temperature (e.g., from about 580 °C to about 700 °C), and gives a higher yield of light olefins with a 1 :1 weight ratio of propylene: ethylene and a smaller amount of dry gas (e.g., less than about 10 wt. %).

[0003] A circulating fluidized bed (CFB) reactor unit is a type of FCC design that is used for catalytic cracking purposes. Typically, a hot catalyst is fed together with the feed and steam for fluidization in an adiabatic riser reactor. The heat for the endothermic cracking reaction is provided, to a large extent, by the temperature of the hot catalyst. During the cracking reaction, the catalyst cools and coke is deposited on the surface of the catalyst particles. At the end of the riser reactor, the catalyst is separated from the gases and sent to the regenerator. In the regenerator, hot air is used to burn off the coke and re-heat the catalyst, after which the catalyst can be re-used for the cracking reactor in the riser reactor. A small amount of catalyst is purged from the system24CHEM0016-WO-ORD2 continuously and fresh catalyst is added to maintain a constant catalyst activity. Current FCCs are used to process and crack heavy feedstocks, such as vacuum residue, atmosphere residue, and / or feedstocks having boiling points of 350 °C or more. It is recognized that it is difficult to perform high-volume processing of the whole feed of certain feedstocks, such as a feedstock that contains hydrocarbons ranging from C4 hydrocarbons up to hydrocarbons having a boiling range of 500 °C to 650 °C and having an American Petroleum Institute (API) gravity ranging from 40 to 80.SUMMARY

[0004] To address the shortcomings set forth above, among others, embodiments of novel CFB- FCC designs are disclosed herein that can accommodate and crack feedstocks that are difficult for existing FCC designs to process, while also yielding a greater quantity of light olefins (e.g., ethylene, propylene, and butenes) and / or aromatics. Embodiments disclosed herein include systems and methods involving a novel reactor pot, riser, and fluidized bed reactor design, as well as process configurations, to facilitate the catalytic cracking of hydrocarbon feedstocks (e.g., light and / or heavy naphtha, condensates and / or light crudes / light crude oil) to produce high value chemicals, such as light olefins and / or aromatics, at either a pilot scale or commercial scale. In general, the disclosed systems and methods relate to the processing of feedstocks containing C4+ hydrocarbons and that have an API gravity ranging from 40-80 and a feed density ranging from 0.6 grams per cubic centimeter (g / cc) to 0.8 g / cc. The disclosed systems and methods generally relate to the use of a circulating fluidized bed (CFB) design with a reactor pot and a riser to catalytically crack feedstock to produce light olefins and / or aromatics using a catalyst or catalyst mixture (e.g., a mixture of USY+ ZSM-5) at reaction temperature ranging from about 600 °C to about 750 °C. The disclosed systems and methods generally relate to a two-stage, hybrid CFB- FCC design that involves the use of a low-velocity, dense-phase reactor pot for primary catalytic cracking reactions, in combination with the use of a higher-velocity, dilute-phase riser for secondary cracking reactions, with predetermined residence times and a high average catalyst solid fraction. Accordingly, the disclosed two-stage, hybrid CFB-FCC designs enable the production of high-value chemicals (e.g., light olefins and / or aromatics) at pilot scale or at commercial scale.

[0005] One such embodiment of a system is a hybrid circulating fluidized bed (CFB) fluid catalytic cracking (FCC) system that includes a first reactor stage having a first diameter, the first reactor stage configured to combine a liquid hydrocarbon feedstock, steam, and a zeolite catalyst to form a lower-velocity, higher-density fluid that facilitates catalytic cracking of long chain-length24CHEM0016-WO-ORD3 hydrocarbons in the liquid hydrocarbon feedstock. The CFB-FCC system includes a second reactor stage directly connected to and extending vertically above the first reactor stage, the second reactor stage having a second diameter that is less than the first diameter, and the second reactor stage configured to receive and transform a first effluent from the first reactor stage into a higher- velocity, lower-density fluid that facilitates catalytic cracking of medium chain-length hydrocarbons in the first effluent. The CFB-FCC system includes a stripping unit connected to the second reactor stage and configured to receive a second effluent from the second reactor stage and to separate coked zeolite catalyst from hydrocarbon products, the hydrocarbon products including olefins, aromatics, or any combination thereof. The CFB-FCC system includes a regenerator connected to the stripping unit and to the first reactor stage, the regenerator configured to receive and combine the coked zeolite catalyst with an oxygen-containing gas to regenerate the coked zeolite catalyst and to provide regenerated zeolite catalyst to the first reactor stage.

[0006] In some embodiments, a ratio of the first diameter to the second diameter ranges from 2: 1 to 3: 1. In some embodiments, a ratio of a vertical height of the first reactor stage to a vertical height of the second reactor stage is 1 :3.5 to 1 :4.5. In some embodiments, the liquid hydrocarbon feedstock (i) includes C4 to C20 hydrocarbons, (ii) has an American Petroleum Institute (API) gravity ranging from 40 to 80, and (iii) has a feed density from 0.6 grams per cubic centimeter (g / cc) to 0.8 g / cc. In some embodiments, the zeolite catalyst is a physical mixture of (i) a rare earth-modified Ultrastable Y (USY)-based, spray-dried catalyst, and (ii) an alkali-treated, mesoporous Zeolite Socony Mobil-5 (ZSM-5)-based, spray-dried additive catalyst. In some embodiments, a ratio of a gas velocity of the lower-velocity, higher-density fluid within the first reactor stage to a gas velocity of the higher-velocity, lower-density fluid within the second reactor stage ranges from 1 :5 to 1 : 10. In some embodiments, a ratio of a concentration of zeolite catalyst in the lower-velocity, higher-density fluid within the first reactor stage to a concentration of zeolite catalyst in the higher-velocity, lower-density fluid within the second reactor stage ranges from 20: 1 to 25 : 1. In some embodiments, the liquid hydrocarbon feedstock includes a light hydrocarbon feedstock, in which the long chain-length hydrocarbons that are catalytically cracked in the first reactor stage include at least C10+ hydrocarbons, and in which the medium chain-length hydrocarbons that are catalytically cracked in the second reactor stage include at least C5-C9 hydrocarbons. In some embodiments, the liquid hydrocarbon feedstock includes a heavy hydrocarbon feedstock, in which the long chain-length hydrocarbons that are catalytically cracked24CHEM0016-WO-ORD4 in the first reactor stage include at least C15+ hydrocarbons, and in which the medium chain-length hydrocarbons that are catalytically cracked in the second reactor stage include at least C5-C14 hydrocarbons. In some embodiments, reaction temperatures within the first and second reactor stages range from 600 degrees Celsius (°C) to 750 °C, and reaction pressures within the first and second reactor stages range from 1 bar gauge (barg) to 4 barg. In some embodiments, a gas residence time within the first reactor stage is 2 seconds to 2.5 seconds and a gas residence time within the second reactor stage is 1 second to 1.5 seconds. In some embodiments, a feed rate of the liquid hydrocarbon feedstock ranges from 365 kilograms per hour (kg / hr) to 375 kg / hr. In some embodiments, a weight ratio of the steam to the liquid hydrocarbon feedstock within the first reactor stage ranges from 1 : 10 to 1 :5. In some embodiments, a weight ratio of the zeolite catalyst to the liquid hydrocarbon feedstock in the first reactor stage ranges from 30: 1 to 40: 1. In some embodiments, a particle density of the zeolite catalyst ranges from 900 kilograms per cubic meter (kg / m3) and 1500 kg / m3. In some embodiments, the zeolite catalyst has an average particle size ranging from 70 micrometers (pm) to 150 pm.

[0007] One such embodiment of a method includes the step of combining liquid hydrocarbon feedstock, steam, and zeolite catalyst in a first reactor stage of a hybrid circulating fluidized bed fluid catalytic cracking (CFB-FCC) system to form a lower-velocity, higher-density fluid in which long chain-length hydrocarbons of the liquid hydrocarbon feedstock are primarily cracked, thereby yielding medium chain-length hydrocarbons in a first effluent. The method includes the step of providing the first effluent from the first reactor stage into a second reactor stage of the hybrid CFB-FCC system to form a higher-velocity, lower-density fluid in which medium chain-length hydrocarbons are primarily cracked, thereby yielding short chain-length hydrocarbons in a second effluent. The method includes the step of stripping the second effluent from the second reactor stage to separate spent zeolite catalyst from hydrocarbon products. The method includes the step of combining the spent catalyst and an oxygen-containing gas to oxidize coke from surfaces of the spent zeolite catalyst, thereby yielding regenerated zeolite catalyst that is recycled to the first reactor stage. The method includes the step of separating the hydrocarbon products into one or more olefin product streams, one or more aromatic product streams, and / or one or more gasoline product streams. In some embodiments, a ratio of a first diameter of the first reactor stage to a second diameter of the second reactor stage ranges from 2: 1 to 3: 1 to transform the first effluent into the higher-velocity, lower-density fluid within the second reactor stage. In some embodiments,24CHEM0016-WO-ORD5 the method includes the step of recycling the one or more gasoline product streams to be combined with the liquid hydrocarbon feedstock, the steam, and the zeolite catalyst in the first reactor stage.

[0008] Aspects and advantages of these exemplary embodiments and other embodiments are discussed in detail herein. Moreover, it is to be understood that both the foregoing information and the following detailed description provide merely illustrative examples of various aspects and embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed aspects and embodiments. Accordingly, these and other objects, along with advantages and features of the present disclosure, will become apparent through reference to the following description and the accompanying drawings. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and may exist in various combinations and permutations.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present disclosure, are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure, and together with the detailed description, serve to explain principles of the embodiments discussed herein. No attempt is made to show structural details of this disclosure in more detail than may be necessary for a fundamental understanding of the embodiments discussed herein and the various ways in which they may be practiced. According to common practice, the various features of the drawings discussed below are not necessarily drawn to scale. Dimensions of various features and elements in the drawings may be expanded or reduced to more clearly illustrate embodiments of the disclosure.

[0010] FIG. 1A is a diagrammatic representation of an embodiment of a hydrocarbon processing system designed to process liquid hydrocarbon feedstock into useful hydrocarbon products, including olefins and / or aromatics, according to an embodiment.

[0011] FIG. IB is a diagrammatic representation of a first reactor stage and a second reactor stage of an example hybrid FCC system, according to an embodiment.

[0012] FIG. 2 is a diagrammatic representation of a method of operating the hydrocarbon processing system to process hydrocarbon feedstock into useful hydrocarbon products, according to an embodiment.

[0013] FIG. 3 is a diagrammatic representation of a pilot-scale hybrid FCC system, according to an embodiment.24CHEM0016-WO-ORD6

[0014] FIG. 4 is a diagrammatic representation of a half treatment train of a commercial-scale embodiment of the FCC hybrid system, according to an embodiment.DETAILED DESCRIPTION

[0015] The present disclosure describes various embodiments related to systems and methods for a CFB-FCC system capable of catalytically cracking hydrocarbon feedstocks to yield useful hydrocarbon products, including olefins and aromatics. The description may use the phrases “in certain embodiments,” “in various embodiments,” “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous. The term “plurality” as used herein refers to two or more items or components. The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, these terms are defined to be within 10 %, preferably within 5 %, more preferably within 1 %, and most preferably within 0.5 %.

[0016] The terms “removing,” “removed,” “reducing,” “reduced,” or any variation thereof, when used in the claims and / or the specification includes any measurable decrease of one or more components in a mixture to achieve a desired result. The use of the words “a” or “an” when used in conjunction with any of the terms “comprising,” “including,” “containing,” or “having,” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The terms “wt. %”, “vol. %”, or “mol. %” refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, which includes the component. In a nonlimiting example, 10 grams of a component in 100 grams of the material is 10 wt. % of the component.

[0017] As used herein, the term “Cx-Cycompounds,” in which x and y are positive integer values, refers to hydrocarbon-based compounds, each compound containing between x and y carbon atoms, with x and y being inclusive. For example, a C2-C5 stream refers to a mixture that substantially contains or entirely contains hydrocarbon-based compounds, each compound containing 2, 3, 4, or 5 carbon atoms. As used herein, the term “Cx+ compounds,” in which x is a positive integer value, refers to hydrocarbon-based compounds, each compound containing at least x carbon atoms. For example, a C3+ stream refers to a mixture that substantially contains or entirely24CHEM0016-WO-ORD7 contains hydrocarbon-based compounds, each compound containing 3 or more (e.g., 3, 4, 5, 6, and so forth) carbon atoms.

[0018] In typical or conventional fluid catalytic crackers (FCCs), a hydrocarbon feed comes into a transport bed reactor / riser through feed atomizing nozzles and is exposed to the catalyst from the regenerator. The feed is subjected to vaporization and cracks down into products as it moves upwards along with the catalyst in a fluid-like fashion. Feed composition, residence time, reaction temperature, catalyst-to-oil (C / O) ratio, hydrocarbon partial pressure, catalyst properties, riser hydrodynamics, average solid fraction, and the reactor design, can all influence conversion and product yields. Currently, existing FCCs typically process heavy feedstocks, such as vacuum gas oil and feedstock having a boiling point range greater than 350 °C, and are operated at low severe conditions, such as a reaction temperature less than 600 °C, with a catalyst: oil weight ratio in the range of 5 wt. % to 10 wt. %.

[0019] However, it is presently recognized that lighter feedstocks, such as naphtha, condensates, and / or light crudes having an API gravity range from about 40 to about 80, are difficult to process in high volumes using conventional FCC designs and process parameters. Present embodiments include hybrid CFB-FCC designs and process parameters capable of accommodating and cracking such lighter feedstocks, while also advantageously yielding a higher proportion of light olefins (e.g., ethylene, propylene, and butenes) and / or aromatics than was possible with previous FCC designs and process parameters. It is presently recognized that, to process the feedstock via fluid catalytic cracking, it is important to continuously circulate catalyst particles at relatively high mass flow rates between the regenerator(s) and the strippers (e.g., about 4 kilograms per second (kg / s) when the catalyst-to-feed ratio of about 40 in a pilot-scale unit, and about 760 kg / s when catalyst- to-feed ratio is about 30 in a commercial-scale unit) in a controlled and reliable fashion. It is also recognized that it is important for the slide valve(s) design to be able to control low to high catalyst circulation rates, and also for the standpipe(s) to have sufficient diameter and length, such that sufficient pressure will be generated to circulate the catalyst without undesirable bridging. Additionally, it is presently recognized that it is important to minimize particle attrition and surface erosion of the catalyst in order to produce higher light olefins and / or aromatics with the desired residence times. Accordingly, the disclosed hybrid CFB-FCC designs and process parameters enable sufficient catalyst circulation, gas flow rates, and other process parameters, such as average24CHEM0016-WO-ORD8 solids volume fractions in the order of about 0.1 to about 0.2, catalyst-to-oil ratios of the order of about 20 to about 100, and contact time of the order of 1 second to 6 seconds.

[0020] For the embodiments disclosed herein, the process parameters for processing feedstocks include a feed rate ranging from about 365 kilograms per hour (kg / h) to about 375 kg / hr for the pilot-scale embodiments. For the commercial-scale embodiments, the process parameters include a feed rate ranging from about 365 tons per hour (t / h) (about 331,000 kg / h) to about 375 t / hr (about 340,000 kg / h) to yield about 1000 kilotons per annum (KT A) of ethylene product as the commercial target. In some embodiments, the disclosed process parameters include the use of a suitable zeolite-based catalyst (e.g., USY + ZSM-5) having a particle density ranging from about 900 kilograms per cubic meter (kg / m3) to about 1500 kg / m3and an average solid particle size ranging from about 70 micrometers (pm) to about 150 pm. As used herein, “USY + ZSM-5” refers to a physical mixture of two zeolite catalysts - namely, a mixture of (i) a rare earth-modified Ultrastable Y (USY)-based, spray-dried catalyst, and (ii) an alkali-treated, mesoporous Zeolite Socony Mobil-5 (ZSM-5)-based, spray-dried additive catalyst. In other embodiments, other zeolite catalysts with similar properties (e.g., acidity and pore size) may be used. In some embodiments, the disclosed process parameters include reaction temperatures ranging from about 675 °C to about 750 °C, a reaction pressure ranging from about 1 bar gauge (barg) to about 4 barg, a catalyst-to- oil ratio ranging from about 25 wt. % to about 60 wt. %, a gas residence time ranging from about 1 second to about 6 seconds, coke formation ranging from about 0.3 wt. % to about 2.0 wt. %, and steam -to-feed ratio from about 10 wt. % to about 20 wt. %.

[0021] It is presently recognized that, to accommodate these process parameters, a conventional FCC design (with two side-by-side vessels, two standpipes, and a single riser) would be too large and would require equipment sizes beyond those typically used or accepted within the field (e.g., a riser diameter greater than 9 feet (ft) or 2.74 meters (m)). As such, pilot-scale and commercialscale embodiments of the disclosed hybrid FCC design enable a high-volume fraction of solids in the reactor pot, while commercial-scale embodiments include multiple risers to ensure that the riser diameter remains in accordance with accepted industry practices. For commercial-scale embodiments of the hybrid FCC design, two parallel treatment trains are implemented to achieve 1000 KTA ethylene product, where each treatment train includes two reactor pots and two risers, in accordance with the hybrid concept, as well as two stripping units and a single regenerator. As such, the disclosed hybrid CFB-FCC designs enable the aforementioned process parameters to be24CHEM0016-WO-ORD9 implemented to convert feedstocks into light olefins and / or aromatics at a pilot scale and at a commercial scale, while ensuring that the dimensions of the FCC components remain in accordance with accepted industry practices.

[0022] FIG. 1A is a diagrammatic representation of an embodiment of a hydrocarbon processing system 100 designed to process liquid hydrocarbon feedstock into useful hydrocarbon products, including olefins and / or aromatics. For the illustrated embodiment, the hydrocarbon processing system 100 includes a hybrid circulating fluidized bed fluid catalytic cracking (CFB-FCC) system 102 (also referred to herein as “hybrid FCC system”) that is integrated with other processing equipment, such as separation unit(s) 104, a hydrogenator 106, and a steam cracker 108. A liquid hydrocarbon feedstock 110 (also referred to herein as “feedstock”) is provided as input to the hybrid FCC system 102. The feedstock 110 generally includes or consists essentially of hydrocarbons having from four to twenty carbon atoms (i.e., C4-C20), has an API gravity ranging from 40-80, and has a feed density ranging from 0.6 grams per cubic centimeter (g / cc) to 0.8 g / cc. For example, in some embodiments, the feedstock 110 is a light crude oil feedstock, a heavy naphtha feedstock, and / or a condensates feedstock. The hybrid FCC system 102 catalytically cracks the feedstock 110 to yield a mixture of hydrocarbon products 112. While referred to herein as hydrocarbon products 112, those skilled in the art will appreciate that the mixture of hydrocarbons that exit the hybrid FCC system 102 may also include certain unreacted hydrocarbons from the hydrocarbon feedstock 110.

[0023] Table 1: Example feedstocks, properties, and designations.24CHEM0016-WO-ORD10| Long chain-length hydrocarbons | _ Cio+ _ | _ Cio+ _ | _ C15+ _ |

[0024] Table 1 indicates some example hydrocarbon feedstocks that may be processed by the system 100, as well as corresponding properties and designations for each of these feedstocks. It should be appreciated that the feedstocks indicated in Table 1 are merely examples, and in other embodiments, other feedstocks may be used, in accordance with the present disclosure. For example, when a hydrocarbon feedstock 110 corresponds to a light feedstock, such as the Full Range Naphtha or the Khuff Gas Condensates indicated in Table 1, or another similar feedstock that substantially includes C4 to C12 hydrocarbons (e.g., 90 wt. % or more) and a limited amount of C1-C4 hydrocarbons (e.g., from about 0.5 wt.% to about 5 wt. %), then the term “long chainlength hydrocarbons” refers to C10+ hydrocarbons, the term “medium chain-length hydrocarbons” refers to C5-C9 hydrocarbons, and the term “short chain-length hydrocarbons” refers to C2-C4 hydrocarbons. When a hydrocarbon feedstock 110 corresponds to a heavy feedstock, such as the Heavy Condensate indicated in Table 1 or another similar feedstock that includes substantial quantities of C4 to C12 hydrocarbons (e.g., 35 wt. % or more), a limited amount of C1-C4 hydrocarbons (e.g., 0.25 wt.% or more), as well as appreciable amounts of C12 to Ci6 hydrocarbons (e.g., 15 wt. % or more), Ci6 to C20 hydrocarbons (e.g., 20 wt.% or more), and C20+ hydrocarbons (e.g., 12 wt. % or more), then the term “long chain-length hydrocarbons” refers to C15+ hydrocarbons, the term “medium chain-length hydrocarbons” refers to C5-C14 hydrocarbons, and the term “short chain-length hydrocarbons” refers to C2-C4 hydrocarbons.

[0025] For the embodiment illustrated in FIG. 1A, the mixture of hydrocarbon products 112 that exits the hybrid FCC system 102 proceeds to one or more separation units 104 designed to separate the hydrocarbons based on boiling points, carbon number, and or functionality (e.g., paraffins, olefins, aromatics). For example, in some embodiments, the one or more separation units 104 may include one or more fractionation columns, one or more vacuum distillation columns, one or more deethanizers, one or more depropanizers, one or more debutanizers, one or more depentanizers, and / or one or more dehexanizers, or the like. For the illustrated embodiment, the one or more separation units 104 separate the mixture of hydrocarbon products 112 into one or more olefin product streams 116 primarily containing olefins (e.g., ethylene, propylene), one or more aromatic product streams 118 primarily containing aromatics (e.g., benzene, toluene, xylenes (BTX)), and a gasoline product stream 120 primarily containing paraffins ranging from C5 paraffins to paraffins having a boiling point of about 216 °C or 421 degrees Fahrenheit (°F). The olefin product streams24CHEM0016-WO-ORD11116 and the aromatic streams 118 may be used, for example, in the manufacture of polymers or fuel blends. In some embodiments, the gasoline streams 120 may be (i) collected and used in the manufacture of fuel blends, (ii) provided as input to the hydrogenator 106 for hydrogenation and then to the steam cracker 108 for steam cracking to produce shorter-chain hydrocarbons (e.g., olefins), or (iii) combined with the hydrocarbon feedstock 110 and recycled back to the hybrid FCC system 102 to further increase the yield of the olefin product streams 116 and / or the aromatic product streams 118.

[0026] For the embodiment illustrated in FIG. 1A, the hybrid FCC system 102 receives a flow of fresh catalyst 122 and steam 123 in addition to the hydrocarbon feedstock 110. When combined with the regenerated catalyst (as discussed below), a mixture 124 of feedstock, steam, and catalyst is formed. The mixture 124 of feedstock, steam, and catalyst is provided as input to one or more first reactor stages 126 (also referred to herein as “reactor pots”) before proceeding to one or more second reactor stages 128 (also referred to herein as “risers” or “riser reactors”). While those skilled in the art will appreciate that a variety of catalytic cracking reactions can occur within either reactor stages 126 and 128, the one or more first reactor stages 126 are designed to primarily or predominantly crack the long chain-length (e.g., C15+) hydrocarbons of the hydrocarbon feedstock 110 into medium chain-length (e.g., C5-C14) hydrocarbons, while the one or more second reactor stages 128 are designed to primarily or predominantly crack medium chain-length hydrocarbons (e.g., C5-C14 hydrocarbons formed in the first reactor stage(s) 126 or present within the hydrocarbon feedstock 110) into short chain-length (e.g., C2-C4) hydrocarbons. As discussed in greater detail below, the dimensions and reaction conditions of the first reactor stage(s) 126 and the second reactor stage(s) 128 differ from one another, which enables these stages to perform the aforementioned chemical conversions.

[0027] For the embodiment illustrated in FIG. 1A, a mixture 130 of spent catalyst and hydrocarbon products exits the second reactor stage(s) 128 and is provided as input to one or more stripping units 131 (also referred to herein as “strippers”). The one or more stripping units 131, which may include cyclone separators, separate the hydrocarbon products 112 from the spent catalyst 132. The spent catalyst 132 is provided as input to one or more regenerators 134, where it is mixed with an oxygen-containing gas (e.g., air, oxygen-enriched air, oxygen) and a layer of coke formed on the surface of the catalyst particles is oxidized and removed, thereby yielding regenerated catalyst 136 that is subsequently recycled into the mixture 124 of feedstock, steam,24CHEM0016-WO-ORD12 and catalyst. Because the oxidation of coke is exothermic, the regenerated catalyst 136 provides a substantial portion of the heat to ensure that the mixture 124 of feedstock, steam, and catalyst is within a desired temperature (e.g., ranging from about 650 °C to about 750 °C) before being introduced into the first reactor stage(s) 126.

[0028] FIG. IB is a diagrammatic representation of a first reactor stage 126A and a second reactor stage 128A of an embodiment of the hybrid FCC system 102. The first reactor stage 126A and the second reactor stage 126A are connected together in series, with the second reactor stage 128A extending vertically upward from the first reactor stage 126A. The first reactor stage 126A has a diameter 150, and the second reactor stage 128A has a diameter 152 smaller than the diameter 150. As a result, the mixture 124 of feedstock, steam, and catalyst that is introduced into the first reactor stage 126A at a temperature ranging from about 650 °C to about 750 °C forms a lower- velocity, higher-density fluid 154 having a temperature ranging from about 675 °C to about 750 °C. This lower-velocity, higher density fluid 154 is then transformed in the second reactor stage 128A into a higher-velocity, lower-density fluid 156 having a temperature ranging from about 650 °C to about 725 °C. Accordingly, the mixture 130 of spent catalyst and hydrocarbon products that exit the top of the second reactor stage 128A has a temperature ranging from about 600 °C to about 700 °C.

[0029] In some embodiments, the diameter 150 of the first reactor stage 126A is about two to three times (2x to 3x) larger than the diameter 152 of the second reactor stage 128A. As a result, the concentration of catalyst particles in the lower-velocity, higher-density fluid 154 within the first reactor stage 126A is twenty to twenty-five times (20x to 25x) greater than the concentration of catalyst particles in the higher-velocity, lower-density fluid 156 within the second reactor stage 128A. For example, in an embodiment, the concentration of catalyst particles within the first reactor stage 126A is about 320 kilograms per cubic meter (kg / m3) to 420 kg / m3, while the concentration of catalyst particles within the second reactor stage 128A is about 14 kilograms per cubic meter (kg / m3) to 20 kg / m3. In some embodiments, the gas velocity at the top of the second reactor stage 128A is five to ten times (5x to lOx) the gas velocity in the first reactor stage 126A. In this manner, the disclosed hybrid FCC system 102 promotes the aforementioned reactions in each of the first reactor stage 126A and the second reactor stage 128A to enable the conversion of the hydrocarbon feedstock 110 into useful hydrocarbon products 112. It may be noted that, unlike certain other FCC designs, such as fast fluidized bed reactor designs, the disclosed hybrid FCC24CHEM0016-WO-ORD13 system 102 lacks a disengagement unit at the top of the second reactor stage 128A or riser, which may desirably reduce the complexity and the installation and / or operational costs of the hybrid FCC system 102.

[0030] FIG. 2 is a diagrammatic representation of a method 200 of operating the hydrocarbon processing system 100 to process hydrocarbon feedstock into useful hydrocarbon products. The method 200 is discussed with reference to elements illustrated in FIGS. 1A and IB. While the method 200 is discussed with reference to an example liquid hydrocarbon feedstock 110 that corresponds to a heavy feedstock, such as the Heavy Condensate indicated in Table 1, in other embodiments, a light feedstock (e.g., Full Range Naphtha, Khuff Gas Condensate) may instead be used. The method 200 begins with the step 202 of flowing a mixture 124 of feedstock, steam, and catalyst into the first reactor stage(s) 126 to form the lower-velocity, higher density fluid 154 in which the long chain-length hydrocarbons (e.g., C15+) of the feedstock 110 are primarily cracked, yielding medium chain-length hydrocarbons (e.g., C5-C14). The method 200 continues with the step 204 of flowing effluent from the first reactor stage(s) 126 into the second reactor stage(s) 128 to form the higher-velocity, lower-density fluid 156 in which medium chain-length hydrocarbons (e.g., C5-C14) are primarily cracked, yielding short chain-length hydrocarbons (e.g., C2-C4). The method 200 continues with the step 206 of flowing effluent from the second reactor stage(s) 128 (i.e., the mixture 130 of spent catalyst and hydrocarbon products) into one or more stripping units 131 to separate the spent catalyst 132 from the hydrocarbon products 112.

[0031] For the embodiment illustrated in FIG. 2, the method 200 continues with the step 208 of flowing the spent catalyst 132 and an oxygen-containing gas into the regenerator(s) 134 to oxidize coke from surfaces of the spent catalyst to regenerate the spent catalyst, thereby yielding regenerated catalyst 136. The method 200 also includes the step 210 of recycling the regenerated catalyst 136 back to the first reactor stage(s) 126. The method 200 includes the step 212 of providing the hydrocarbon products 112 to one or more separation units 104 to separate one or more olefin product streams 116, one or more aromatic product streams 118, and / or one or more gasoline product streams 120. For the illustrated embodiment, the method 200 further includes the step 214 of recycling the gasoline product stream(s) 120 back to the first reactor stage(s) 126. As noted, in other embodiments, the gasoline product streams 120 may alternatively be provided to the hydrogenator 106 and / or the steam cracker 108 for further processing.24CHEM0016-WO-ORD14

[0032] FIG. 3 is a diagrammatic representation of a pilot-scale embodiment of the FCC hybrid system 300. FIG. 3 is discussed with reference to elements illustrated in FIG. 1A and IB. In some embodiments, the FCC hybrid system 300 may be operated based on targeted process parameters, such as a typical gas velocity of about 10 meters per second (m / sec) at the top of the second reactor stage (riser), a gas velocity of about 1.5 m / sec in the first reactor stage (reactor pot), and including a regenerator and stripping units for the closed circulating fluidized bed system for pilot-scale operation for processing a typical liquid hydrocarbon feedstock composition. In some embodiments, the pilot-scale FCC hybrid system 300 is implemented using the design and process parameters indicated in Table 2.

[0033] For the pilot-scale embodiment illustrated in FIG. 3, the mixture 124 of feedstock, steam, and catalyst 124 is introduced below the first reactor stage 302 (reactor pot), as indicated by the arrow 304. The mixture 124 forms the lower-velocity, higher-density fluid 154 to promote the catalytic cracking of long chain-length hydrocarbons (e.g., C15+) into medium chain-length hydrocarbons (e.g., C5-C14) within the first stage reactor 302. The effluent from the first reactor stage 302 is then introduced into the second reactor stage 306 (riser), where it is transformed into the higher-velocity, lower-density fluid 156 to promote the catalytic cracking of medium chainlength hydrocarbons (e.g., C5-C14) into short chain-length hydrocarbons (e.g., C2-C4). The higher- velocity, lower-density fluid 156 travels to the top of the second reactor stage 306, and the mixture 130 of spent catalyst and hydrocarbon products is subsequently introduced into one or more stripping units 308, which may include one or more cyclone units, to separate the spent catalyst 132 from the hydrocarbon products 112. The hydrocarbon products 112 may be collected via the outlet(s) 310 of the one or more stripping units 308, while, under the force of gravity, the spent catalyst 132 falls and is delivered to the regenerator 312 via a standpipe 314. An oxygen-containing gas (e.g., air) is introduced into the regenerator 312, as indicated by the arrow 316, and combined with the spent catalyst 132 to oxidize a layer of coke from the surfaces of the catalyst. The regenerator 312 includes one or more cyclone separators 318 to separate the regenerating catalyst from the flue gas that is generated during coke oxidation, such that the flue gases exit via outlet 320. Subsequently, the hot, regenerated catalyst 136 collects in a standpipe 322, and is then recycled back to the first reactor stage 302.

[0034] Table 2 Process and design parameters for an example embodiment of the pilot-scale, hybrid FCC design.24CHEM0016-WO-ORD15

[0035] FIG. 4 is a diagrammatic representation of a half treatment train 400 of a commercialscale embodiment of the FCC hybrid system 402. FIG. 4 is discussed with reference to elements illustrated in FIG. 1A and IB. In some embodiments, the commercial-scale FCC hybrid system 402 may be operated based on targeted process parameters, such as a typical gas velocity of about15 meters per second (m / sec) at the top of the second reactor stage (riser), a gas velocity of about24CHEM0016-WO-ORD161.7 m / sec in the first reactor stage (reactor pot), with the system including regenerators and stripping units for the closed circulating fluidized bed system for commercial-scale operation for processing a typical hydrocarbon (e.g., condensate) feedstock composition. In some embodiments, the commercial-scale FCC hybrid system 402 is implemented using the design and process parameters indicated in Table 3.

[0036] For the embodiment of FIG. 4, it should be appreciated that the full treatment train of the FCC hybrid system 402 includes two of the illustrated half treatment trains 400 implemented in parallel in order to achieve the desired 1000 KTA ethylene commercial target. This desirably enables one half treatment train 400 of the FCC hybrid system 402 to be intermittently taken offline for maintenance and / or repair while the other half treatment train 400 remains operational. The illustrated embodiment of the half treatment train 400 includes two first reactor stages (reactor pots) 404A and 404B, two second reactor stages (risers) 406A and 406B, and two separation units 408A and 408B implemented in parallel, with a shared or common regenerator 410. As such, it may be appreciated that, for the illustrated embodiment, the full treatment train of the FCC hybrid system 402 includes four first reactor stages, four second reactor stages, four separation units, and two regenerators in total.

[0037] For the embodiment of the half treatment train 400 illustrated in FIG. 4, the mixture 124 of feedstock, steam, and catalyst 124 is introduced below the first reactor stages 404A, 404B (reactor pots), as indicated by arrows 412A, 412B. The mixture 124 forms the lower-velocity, higher-density fluid 154 to promote the catalytic cracking of long chain-length hydrocarbons (e.g., C15+) into medium chain-length hydrocarbons (e.g., C5-C14) within the first reactor stages 404A, 404B. The effluent from the first reactor stages 404A, 404B is then introduced into the second reactor stages 406A, 406B (riser), where it is transformed into the higher-velocity, lower-density fluid 156 to promote the catalytic cracking of medium chain-length hydrocarbons (e.g., C5-C14) into short chain-length hydrocarbons (e.g., C2-C4).

[0038] The higher-velocity, lower-density fluid 156 travels to the top of the second reactor stages 406A, 406B, and the mixture 130 of spent catalyst and hydrocarbon products is subsequently introduced into the stripping units 408A, 408B, which may include one or more cyclone units, to separate the spent catalyst 132 from the hydrocarbon products 112. The hydrocarbon products 112 may be collected via the outlets 414A, 414B of the stripping units 408A, 408B, while, under the force of gravity, the spent catalyst 132 falls and is delivered to the regenerator 410 via standpipes24CHEM0016-WO-ORD17416A, 416B. An oxygen-containing gas is introduced into the regenerator 410, as indicated by the arrow 418, and combined with the spent catalyst 132 to oxidize a layer of coke from the surfaces of the catalyst. The regenerator 410 includes cyclone separators 420 to separate the regenerating catalyst from the flue gas that is generated during coke oxidation, such that the flue gases exit via outlet 422. Subsequently, the hot, regenerated catalyst 136 collects in standpipes 424A, 424B, and is subsequently recycled back to the first reactor stages 404A, 404B.

[0039] Table 3. Process and design parameters for an example embodiment of the commercialscale, hybrid FCC design having a full treatment train having four reactor pots, four risers, and two regenerators.24CHEM0016-WO-ORD18

[0040] Experimental Results

[0041] Laboratory scale tests performed in fixed-bed reactors and small-scale risers (e.g., under 1-inch inner diameter) have proven the concept of conducting the desired conversion for the cracking chemistry in circulating fluidized bed (CFB) reactor systems. In a model experiment, a lab-scale, 1-inch inner diameter second reactor stage (riser) was used to prove the initial concept for catalytic cracking via CFB reactor system to optimize process conditions. The laboratory scale tests were performed using Khuff gas condensate as the hydrocarbon feedstock, with the Khuff gas condensate having the parameters and composition indicated in Tables 4 and 5. Table 6 indicates single-pass conversion and product yields distribution with Khuff gas condensate in the model catalytic cracker based on certain process parameters, including a reaction temperature of 675 °C, a steam -to-oil feed ratio of 25 wt. %, and a catalyst-to-feed weight ratio of 25 wt. %, using the lab-scale riser reactor.

[0042] Table 4 Parameters of an Example Hydrocarbon Feedstock (Khuff gas condensate).

[0043] Table 5. Compositional Breakdown of Example Typical Hydrocarbon Feedstock (Khuff gas condensate).24CHEM0016-WO-ORD19

[0044] Table 6. Example hydrocarbon product breakdown when Khuff gas condensate is used as the feedstock.24CHEM0016-WO-ORD20

[0045] As such, studies in small-scale reactive systems have shown that the light olefin (e.g., ethylene + propylene + butenes) yields can be maximized while minimizing methane formation under general conditions that include dense-phase flows (e.g., an average solids volume fractions in the riser of the order of 0.1-0.2, using a catalyst-to-oil ratio of the order of 20-100, and contact time of the order of 1-6 seconds with minimal back-mixing). In addition, it is presently recognized that the aromatics yields are typically maximized under similar conditions, except that back- mixing favors the formation of aromatics. It may be appreciated that, for embodiments in which the gasoline streams are recycled back to the hybrid FCC system for further cracking, the yield of high value olefines (e.g., ethylene, propylene, n-butenes) may be further increased.

[0046] Other objects, features, and advantages of the disclosure will become apparent from the foregoing figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the disclosure, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from the detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

Claims

24CHEM0016-WO-ORD21CLAIMS1. A hybrid circulating fluidized bed fluid catalytic cracking (CFB-FCC) system comprising: a first reactor stage having a first diameter, the first reactor stage configured to combine a liquid hydrocarbon feedstock, steam, and a zeolite catalyst to form a lower-velocity, higher-density fluid that facilitates catalytic cracking of long chain-length hydrocarbons in the liquid hydrocarbon feedstock; a second reactor stage directly connected to and extending vertically above the first reactor stage, the second reactor stage having a second diameter that is less than the first diameter, and the second reactor stage configured to receive and transform a first effluent from the first reactor stage into a higher-velocity, lower-density fluid that facilitates catalytic cracking of medium chainlength hydrocarbons in the first effluent; a stripping unit connected to the second reactor stage and configured to receive a second effluent from the second reactor stage and to separate coked zeolite catalyst from hydrocarbon products, the hydrocarbon products including olefins, aromatics, or any combination thereof; and a regenerator connected to the stripping unit and to the first reactor stage, the regenerator configured to receive and combine the coked zeolite catalyst with an oxygen-containing gas to regenerate the coked zeolite catalyst and to provide regenerated zeolite catalyst to the first reactor stage.

2. The hybrid CFB-FCC system of claim 1, wherein a ratio of the first diameter to the second diameter ranges from 2: 1 to 3 : 1.

3. The hybrid CFB-FCC system of any of claims 1 or 2, wherein a ratio of a vertical height of the first reactor stage to a vertical height of the second reactor stage is 1 :3.5 to 1 :4.5.

4. The hybrid CFB-FCC system of any one of claims 1-3, wherein the liquid hydrocarbon feedstock (i) includes C4 to C20 hydrocarbons, (ii) has an American Petroleum Institute (API) gravity ranging from 40 to 80, and (iii) has a feed density from 0.6 grams per cubic centimeter (g / cc) to 0.8 g / cc.

5. The hybrid CFB-FCC system of any one of claims 1-4, wherein the zeolite catalyst is a physical mixture of (i) a rare earth-modified Ultrastable Y (USY)-based, spray-dried catalyst, and (ii) an alkali-treated, mesoporous Zeolite Socony Mobil-5 (ZSM-5)-based, spray-dried additive catalyst.24CHEM0016-WO-ORD226. The hybrid CFB-FCC system of any one of claims 1-5, wherein a ratio of a gas velocity of the lower-velocity, higher-density fluid within the first reactor stage to a gas velocity of the higher- velocity, lower-density fluid within the second reactor stage ranges from 1 :5 to 1 : 10, and wherein a ratio of a concentration of zeolite catalyst in the lower-velocity, higher-density fluid within the first reactor stage to a concentration of zeolite catalyst in the higher-velocity, lower-density fluid within the second reactor stage ranges from 20: 1 to 25 : 1.

7. The hybrid CFB-FCC system of any one of claims 1-6, wherein the liquid hydrocarbon feedstock comprises a light hydrocarbon feedstock, wherein the long chain-length hydrocarbons that are catalytically cracked in the first reactor stage include at least Cio+ hydrocarbons, and wherein the medium chain-length hydrocarbons that are catalytically cracked in the second reactor stage include at least C5-C9 hydrocarbons.

8. The hybrid CFB-FCC system of any one of claims 1-6, wherein the liquid hydrocarbon feedstock comprises a heavy hydrocarbon feedstock, wherein the long chain-length hydrocarbons that are catalytically cracked in the first reactor stage include at least C15+ hydrocarbons, and wherein the medium chain-length hydrocarbons that are catalytically cracked in the second reactor stage include at least C5-C14 hydrocarbons.

9. The hybrid CFB-FCC system of any one of claims 1-8, wherein reaction temperatures within the first and second reactor stages range from 600 degrees Celsius (°C) to 750 °C, and wherein reaction pressures within the first and second reactor stages range from 1 bar gauge (barg) to 4 barg.

10. The hybrid CFB-FCC system of any one of claims 1-9, wherein a gas residence time within the first reactor stage is 2 seconds to 2.5 seconds and a gas residence time within the second reactor stage is 1 second to 1.5 seconds.

11. The hybrid CFB-FCC system of any one of claims 1-10, wherein a feed rate of the liquid hydrocarbon feedstock ranges from 365 kilograms per hour (kg / hr) to 375 kg / hr, and wherein a weight ratio of the steam to the liquid hydrocarbon feedstock within the first reactor stage ranges from 1 : 10 to 1 :5.

12. The hybrid CFB-FCC system of any one of claims 1-11, wherein a weight ratio of the zeolite catalyst to the liquid hydrocarbon feedstock in the first reactor stage ranges from 30: 1 to 40: 1, and wherein a particle density of the zeolite catalyst ranges from 900 kilograms per cubic meter (kg / m3) and 1500 kg / m3, and wherein the zeolite catalyst has an average particle size ranging from 7024CHEM0016-WO-ORD23 micrometers (pm) to 150 pm.

13. A method comprising: combining liquid hydrocarbon feedstock, steam, and zeolite catalyst in a first reactor stage of a hybrid circulating fluidized bed fluid catalytic cracking (CFB-FCC) system to form a lower- velocity, higher-density fluid in which long chain-length hydrocarbons of the liquid hydrocarbon feedstock are primarily cracked, thereby yielding medium chain-length hydrocarbons in a first effluent; providing the first effluent from the first reactor stage into a second reactor stage of the hybrid CFB-FCC system to form a higher-velocity, lower-density fluid in which medium chainlength hydrocarbons are primarily cracked, thereby yielding short chain-length hydrocarbons in a second effluent; stripping the second effluent from the second reactor stage to separate spent zeolite catalyst from hydrocarbon products; combining the spent catalyst and an oxygen-containing gas to oxidize coke from surfaces of the spent zeolite catalyst, thereby yielding regenerated zeolite catalyst that is recycled to the first reactor stage; and separating the hydrocarbon products into one or more olefin product streams, one or more aromatic product streams, and / or one or more gasoline product streams.

14. The method of claim 13, wherein a ratio of a first diameter of the first reactor stage to a second diameter of the second reactor stage ranges from 2: 1 to 3: 1 to transform the first effluent into the higher-velocity, lower-density fluid within the second reactor stage.

15. The method of any of claims 13 or 14, further comprising recycling the one or more gasoline product streams to be combined with the liquid hydrocarbon feedstock, the steam, and the zeolite catalyst in the first reactor stage.

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