BR112020000843B1 - METHOD FOR CONVERTING A REAGENT GAS - Google Patents

Abstract

According to one or more embodiments disclosed herein, a reactant gas can be converted by a method comprising introducing the reactant gas into a fluidized bed reactor. The main reactor vessel of the fluidized bed reactor may be tapered such that the upstream portion of the main reactor vessel comprises a smaller cross-sectional area than the downstream portion of the main reactor vessel.

Description

BACKGROUND FIELD

[0001] The present disclosure refers, generally, to chemical processing and, more specifically, to reactor designs and systems used in chemical processing.

BACKGROUND OF THE TECHNIQUE

[0002] Many reactions using gas streams as reactants form additional moles of gas as a result of the reaction (that is, when there are more gas molecules after reaction than before). For example, dehydrogenation and cracking reactions produce additional moles of product compared to those that existed in the reactant stream. When the reactant and product are gases, changes in local gas velocities can result in the reactor forming these additional molecules.

BRIEF SUMMARY

[0003] When a reaction produces additional gas molecules compared to those in the reactant stream, pressure can build up in the reactor or other components of the system. These changes in pressure can result in local changes in the velocity of the gas and/or solid catalyst in a reactor, such as a fluidized bed reactor. Changes in gas velocity can also affect the density of the suspension in a local portion of the reactor, which generally correlates with the amount of catalyst per volume in the reactor at a local location. Controlling the surface fluid velocity and/or suspension density in a reactor can be important to the overall chemical conversion rate of a reaction and/or the operational specifications (e.g., size, shape, etc.) of a reactor. Therefore, there is a continuing need for methods and apparatus for processing gas streams under reaction conditions that increase the number of gas molecules, while controlling the surface velocity and/or suspension density throughout the reactor.

[0004] More specifically, it has been found that the formation of excess gas molecules following the reaction in relation to the amount of gas in the feed reactant can cause increases in the superficial gas velocity and decrease the suspension density of the reactor contents. As used herein, “suspension density” refers to the calculated density of both the solids content (e.g., catalyst) and gas content (e.g., gaseous reactants and products) in the reactor. For example, as more gas is produced through the reaction, the surface velocity of the gases can increase, sometimes dramatically, in a fluidized bed reactor. Additionally, the suspension density (including the reactant and product gas and the solid particulate catalyst) may decrease so that conversion is decreased due to the lack of catalyst relative to the reactant gas. As conversion is negatively affected, it may be necessary to increase reactor volume, adding undesirable capital costs. Additionally, the high gas velocity in the reactor can make it difficult to control the amount of catalyst in the system at a given time.

[0005] In order to mitigate or completely stop the rise in gas velocity and the decrease in suspension density, it has been discovered that a fluidized bed reactor with an increasing cross-sectional area can be utilized for gas-based reactions that produce excess gas molecules. For example, a fluidized bed reactor that is narrower in its upstream portion than its downstream portion may allow relatively constant surface gas velocity, suspension density, or both in the upstream and downstream portions of the bed reactor. fluidized. In contrast, conventional fluidized bed reactors with tubular shapes generally have high gas velocity as a function of height. Proper geometry design for the fluidized bed reactor, such as a conical geometry, can allow for reduced increases in gas velocity and/or suspension density losses as the reaction progresses in the downstream portions of the reactor. That is, when the reaction occurs along the height of the reactor (assuming the reaction products are moving upward), the increase in cross-sectional area compensates for the increase in gas volume and therefore can maintain the reaction rate. relatively constant gas. Relative stability of gas velocity, suspension density, or both may allow for mitigation of the problems discussed above.

[0006] According to one or more embodiments, a reactant gas can be converted by a method comprising introducing the reactant gas into a fluidized bed reactor, such that the reactant gas is contacted by a catalyst, catalytically reacting the reactant gas to forming a reaction product in the fluidized bed reactor and passing the reaction product and any unreacted reactant gas through a transition section. The fluidized bed reactor may comprise a main reactor vessel comprising an upstream portion and a downstream portion, and a transition section connected to the downstream portion of the main reactor vessel. The reactant gas may enter the fluidized bed reactor at or near the upstream portion of the main reactor vessel. The reaction may result in additional gas molecules in relation to the reactant gas. The main reactor vessel may be tapered so that the upstream portion of the main reactor vessel comprises a smaller cross-sectional area than the downstream portion of the main reactor vessel, so that the surface velocity of the gases in the bed reactor fluidized bed reactor in the downstream portion of the main reactor vessel may be less than or equal to 140% of the surface velocity of the gases in the fluidized bed reactor in the upstream portion of the main reactor vessel. According to one or more additional embodiments, a reactant gas may be converted by a method comprising introducing the reactant gas into a fluidized bed reactor, such that the reactant gas is contacted by a catalyst, catalytically reacting the reactant gas to form a reaction product in the fluidized bed reactor and pass the reaction product and any unreacted reactant gas through the transition section. The fluidized bed reactor may comprise a main reactor vessel comprising an upstream portion and a downstream portion, and a transition section connected to the downstream portion of the main reactor vessel. The reactant gas may enter the fluidized bed reactor at or near the upstream portion of the main reactor vessel. The reaction may result in additional gas molecules in relation to the reactant gas. The main reactor vessel may be tapered so that the upstream portion of the main reactor vessel comprises a smaller cross-sectional area than the downstream portion of the main reactor vessel, so that the suspension density in the fluidized bed reactor in the downstream portion of the main reactor vessel may be greater than or equal to 25% of the suspension density in the fluidized bed reactor in the upstream portion of the main reactor vessel.

[0007] It should be understood that both the previous brief summary and the following detailed description present embodiments of the technology and should provide an overview or context for understanding the nature and character of the technology, as claimed. The accompanying drawings are included to provide a further understanding of the technology and are incorporated into this specification and constitute part thereof. The drawings illustrate various modalities and, together with the description, serve to explain the principles and operations of the technology. Additionally, the drawings and descriptions are intended to be illustrative only and are not intended to limit the scope of the claims in any way.

[0008] Additional features and advantages of the technology disclosed herein will be set forth in the following detailed description and, in part, will be readily apparent to persons skilled in the art from the description or recognized practicing the technology as described herein. including the following detailed description, the claims, as well as the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following detailed description of specific embodiments of the present disclosure may be better understood when read in combination with the following drawings, in which similar structure is indicated with similar reference numerals and in which:

[0010] FIG. 1 schematically represents a fluidized bed reactor according to one or more embodiments described herein;

[0011] FIG. 2 schematically represents another fluidized bed reactor according to one or more embodiments described herein;

[0012] FIG. 3 schematically represents an example chemical processing system that can utilize the presently described fluidized bed reactors in accordance with one or more embodiments described herein; It is

[0013] FIGS. 4A-4D represent modeled data from three example embodiments and a comparative example in accordance with one or more embodiments described herein.

[0014] It should be understood that the drawings are schematic in nature and do not include some components of a reactor system commonly employed in the art, such as, without limitation, temperature transmitters, pressure transmitters, flow meters, pumps, valves and similar. It would be known that these components are within the spirit and scope of the present disclosed embodiments. However, operational components, such as those described in the present disclosure, may be added to the embodiments described in this disclosure.

[0015] Reference will now be made in more detail to various embodiments, some embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used in all drawings to refer to the same or similar parts.

DETAILED DESCRIPTION

[0016] Embodiments relating to methods for processing chemical product streams in a fluidized bed reactor are described here. In one or more embodiments, the chemical stream that is processed may be referred to as a feed stream or reactant stream and the chemical stream that includes the product of the chemical reaction may be referred to as a product stream. It should be understood that the product stream may include various components of the feed stream when feed stream conversion is incomplete, which may be typical of many chemical reactions.

[0017] The systems and apparatus described here, such as the fluidized bed reactors described here, can be used as processing equipment for various fluidized catalytic reactions. The described methods and apparatus can be used in reactions in which a gaseous feed is converted to a gaseous product stream by contacting a solid state catalyst, such as a particulate catalyst. For example, hydrocarbons as well as other chemical stocks can be converted into desirable products through the use of fluidized bed reactors. Fluidized bed reactors serve many purposes in industry, including dehydrogenation of paraffins and/or alkyl aromatics, cracking of hydrocarbons (i.e., fluid catalytic cracking), chlorination of olefins, oxidations of naphthalene to phthalic anhydride, production of acrylonitrile from propylene, ammonia and oxygen, Fischer-Tropsch synthesis, ethylene polymerization, dehydration of hydrocarbons to form light olefins and some methanol-to-olefin (MTO) reactions.

[0018] According to one or more embodiments, some of these reactions, such as without limitation, dehydrogenation, cracking, dehydration and MTO, may form additional moles of gas molecules in relation to the moles of feed gas molecules. When the products are gaseous, the local pressure in the reactor can be elevated as the reaction progresses. Such reactions, in some embodiments, can be represented by the formula aR ^ bP + cZ, where R represents the reactant species, P represents the product species, Z represents another product species, and a, b and c each represent the relative quantity of each species used in the reaction. For example, a dehydrogenation reaction would result in hydrogen as Z, or in a dehydration reaction Z would be water. When a is less than b+c, additional molecules are formed by the reaction, which is the reaction to which the presently described methods and apparatus can be directed. As such, this reaction forms two or more product molecules from each reactant molecule that is reacted. It is noted that the above equation is only an example chemical reaction and it should be understood that other reactions are within the scope of this disclosure, such as those in which two or more products and/or reactants are present.

[0019] According to some embodiments, the fluidized bed reactors described herein can process reactant gas comprising ethane, propane, n-butane, isobutane, and ethylbenzene (e.g., at least 80% by weight, 90% by weight, 95% by weight or even 99% by weight of any of these reactant gases, or combinations thereof) to form product gas comprising isomers of ethylene, propylene, butene and butadiene, isobutene, styrene or combinations thereof (e.g., at least at least 10% by weight, at least 20% by weight, at least 30% by weight, at least 40% by weight, at least 50% by weight, at least 70% by weight or even at least 90% by weight of any of these product gases or combinations thereof). For example, gases suitable for dehydrogenation are contemplated herein.

[0020] Now, with reference to FIG. 1, an embodiment of a fluidized bed reactor is depicted which can process a feed stream by contact with a solid catalyst. According to one or more embodiments described herein, the fluidized bed reactor 202 may comprise a main reactor vessel 250, a transition section 258, and a downstream reactor section 230, such as a riser. The transition section 258 may connect the main reactor section 250 with the downstream reactor section 230. As depicted in FIG. 1, the main reactor section 250 may be positioned below the downstream reactor section 230. Such a configuration may be referred to as an upflow configuration in the fluidized bed reactor 202. A transport riser 430 may provide one or more of reactant and catalyst gas to the fluidized bed reactor 202 and the gaseous reactants and products, as well as the catalyst, may move through a feed manifold 260, through the main reactor vessel 250, through the transition section 258 and to and from through the downstream reactor section 230. As depicted in FIG. 1, the movement of the catalyst and the product and reactant gases is upward (represented by the x axis). As described here, “surface velocity” refers to the surface velocity of a material in the direction of global material flow (through the plane perpendicular to the x-axis).

[0021] As described herein, the main reactor section 250 may include a vessel, drum, barrel, vat or other container suitable for a given chemical reaction. In one or more embodiments, the main reactor vessel 250 may have a substantially circular cross-sectional shape (which is representative of the cross-sectional view of FIG. 1). Alternatively, the main reactor vessel 250 may be non-circular in cross-section. For example, the main reactor vessel 250 may comprise cross-sectional shapes of triangles, rectangles, pentagons, hexagons, octagons, ovals, or other polygons or curved closed shapes, or combinations thereof. The main reactor vessel 250, as used throughout this disclosure, may generally include a metallic structure and may additionally include refractory linings or other materials used to protect the metallic structure and/or control process conditions. As depicted in FIG. 1, the main reactor vessel 250 may include a catalyst inlet port from the lower reactor portion 252 defining the connection of the transport riser 430 to the main reactor vessel 250.

[0022] The main reactor vessel 250 may be connected to a transport riser 430 which, in operation, may supply processed catalyst and/or reactant chemicals in a feed stream. The processed catalyst and/or reactant chemicals may be mixed with a feed distributor 260 housed in the main reactor vessel 250. In one or more embodiments, the feed distributor 260 may be operable to dispense the first feed stream and the second feed chain at all hood distributor speeds from 76.2 m/s (250 ft/s) to 24.4 m/s (80 ft/s). In such embodiments, various feed streams may be utilized while maintaining the desired reactor characteristics, such as operating as a fluidized bed, turbulent, or fast bubbling reactor in the main reactor vessel 250 and as a dilute phase riser reactor. in the downstream reactor section 230. For example, according to one or more embodiments, a hood distributor velocity of about 24.4 m/s (80 ft/s) may be utilized in the main reactor vessel 250 to naphtha feeds, while a hood distributor velocity of about 76.2 m/s (250 ft/s) can be utilized in the main reactor vessel 250 for propane feeds. In additional embodiments, some orifices could be closed in the fluidized bed reactor 202 when naphtha is used as a feed stream. “Hood distributor speed” refers to the speed at which gas exits the distributor, sometimes through a hood. For example, suitable dispensers are disclosed in US Patent 9,370,759, the teachings of which are incorporated herein by reference in their entirety.

[0023] As represented in FIG. 1, the main reactor vessel 250 may be connected to the downstream reactor section 230 via the transition section 258. The transition section 258 may be tapered from the size of the cross section of the main reactor vessel 250 to the size of the cross section of the downstream reactor section 230 such that the transition section 258 projects inwardly from the main reactor vessel 250 to the downstream reactor section 230.

[0024] In one or more embodiments, the downstream reactor section 230 may be generally cylindrical in shape (i.e., having a substantially circular cross-sectional shape) or may alternatively be non-cylindrical in shape, such as prism shape with cross-sectional shape of triangles, rectangles, pentagons, hexagons, octagons, ovals or other polygons or curved closed shapes or combinations thereof. The downstream reactor section 230, as used throughout the present disclosure, may generally include a metallic structure and may additionally include refractory linings or other materials used to protect the metallic structure and/or control process conditions.

[0025] In some embodiments, such as those where the main reactor vessel 250 and the downstream reactor section 230 have similar cross-sectional shapes, the transition section 258 may be shaped like a log. For example, for an embodiment of a reactor portion 200 comprising a main reactor vessel of cylindrical cross section 250 and cylindrical downstream reactor section 230, the transition section 258 may have a frustoconical shape. However, it should be understood that a wide variety of main reactor vessel 250 shapes are contemplated herein that connect various shapes and sizes of transition sections 258 and downstream reactor sections 230.

[0026] According to one or more embodiments, the main reactor vessel 250 may be tapered outward relative to the general flow direction of materials (i.e., the x-axis direction) in the fluidized bed reactor 202. For example , FIG. 1 depicts a linearly expanding main reactor vessel 250, which is shaped like a segment of a cone. Although the tapered geometry may be linear in some embodiments, some embodiments disclosed herein are not linearly tapered, such as that depicted in FIG. two.

[0027] With reference to FIG. 1 or 2, the main reactor vessel 250 may comprise an upstream portion 204 and a downstream portion 206. The upstream portion 204 may be the portion of the main reactor vessel 250 adjacent to the feed manifold 260 and the downstream portion 206 may be the portion of the main reactor vessel 250 adjacent to the transition section 258. A central portion 208 of the main reactor vessel 250 may be positioned equidistant between the upstream portion 204 and the downstream portion 206 (based on the height in x direction of the main reactor vessel 250). Generally, the upstream portion 204 of the main reactor vessel 250 may have a smaller cross-sectional area than the downstream portion 206 of the main reactor vessel 250, defining a bottleneck in the cross-sectional geometry of the main reactor vessel 250. According described herein, unless explicitly stated otherwise, “cross-sectional area” refers to the cross-sectional area of a portion of the reactor part in a plane substantially orthogonal to the direction of mean flow of reactants and/or products (i.e., the plane perpendicular to the x-axis in FIG. 1). For example, in FIG. 1, the cross-sectional area of the main reactor vessel 250, the transition section 258, and the downstream reactor section 230, or any portion of each, are in the direction of a plane defined by the horizontal direction and the direction toward the page (orthogonal to the direction of fluid movement, i.e., vertically upward in FIG. 1). In additional embodiments, the upstream portion 204 may have a smaller cross-sectional area than the central portion 208 and the central portion 208 may have a smaller cross-sectional area than the downstream portion 206. As such, in some embodiments, the cross-sectional area of the central portion 208 may be smaller than the cross-sectional area of the downstream portion 206 and larger than the cross-sectional area of the upstream portion 204.

[0028] In one or more embodiments, the cross-sectional area of the downstream portion 206 of the main reactor vessel 250 may be 1.2 to 1.8 times that of the upstream portion 204 of the main reactor vessel 250 (e.g. example, from 1.2 to 1.4, from 1.4 to 1.6 or from 1.6 to 1.8). According to one or more embodiments, the main reactor vessel 250 may have a height of 0.6 m to 3.6 m (2 ft to 12 ft) (e.g., 0.6 m to 1.2 m (2 ft). to 4 ft), from 1.2 m to 1.8 m (4 ft to 6 ft), from 1.8 m to 2.4 m (6 ft to 8 ft), from 2.4 m to 3.0 m (8 ft to 10 ft), or from 3.0 m to 3.7 m (10 ft to 12 ft)).

[0029] In one or more embodiments, the taper of the main reactor vessel 250 may be described by a slope in a particular portion of the main reactor vessel 250. For example, the main reactor vessel 250 may have a measurable slope (i.e. is, half the width change divided by the height change) in the upstream portion 204, the downstream portion 206, and the central portion 208. That is, a constant cross-sectional shape would have a slope of 0. In the embodiment of FIG. 1, the slope may be substantially constant throughout the main reactor vessel 250, such as substantially constant with respect to the upstream portion 204, the downstream portion 206, and the central portion 208. Such substantially constant slope corresponds to a linear profile of the vessel. of main reactor 250. In additional embodiments, such as that of FIG. 2, the main reactor vessel 250 may comprise a slope that is less at or near the downstream portion 206 than that at or near the upstream portion 204 of the main reactor vessel 250. In such embodiments, the slope at the central portion 208 may be less than that of the upstream portion 204 and greater than that of the downstream portion 206. As explained in the Examples below, the slope and relative shape of the main reactor vessel 250 may affect the surface gas velocity and/or or the suspension density at the location positioned within the main reactor vessel 250.

[0030] As depicted in FIGS. 1 and 2, the inwardly tapered transition section 258 and the outwardly tapered main reactor vessel 250 form a geometric configuration of the fluidized bed reactor 202 in which the portion of the fluidized bed reactor 202 with the largest cross-sectional area is at the point where the transition section 258 and the main reactor vessel 250 are connected (i.e., at or near the downstream portion 206 of the main reactor vessel 250). The downstream reactor section 230 may have a smaller cross-sectional area than the transition section 258 and the main reactor vessel 250. In one or more embodiments, the downstream reactor section 230 may have a smaller cross-sectional area. than the upstream portion 204 of the main reactor vessel 250.

[0031] According to the embodiments described herein, at least one purpose of the outwardly tapered main reactor vessel 250 is its effect on the superficial gas velocity and/or suspension density at local positions in the main reactor vessel 250. It may be desirable to have relatively constant surface gas velocity and/or suspension density throughout the height of the main reactor vessel 250. For example, it may be desirable to have similar surface gas velocity and/or suspension density at two or more of the upstream portion 204 as well as the downstream portion 206 or the central portion 208.

[0032] According to one or more embodiments, the surface velocity of gases in the fluidized bed reactor in the downstream portion 206 of the main reactor vessel 250 may be less than or equal to 140% (such as, for example, less than or equal to to 130%, less than or equal to 120%, less than or equal to 110%, less than or equal to 100%, less than or equal to 90% or even less than or equal to 80%) of the surface velocity of the gases in the fluidized bed reactor in the upstream portion 204 of the main reactor vessel 250. For example, in additional embodiments, the surface velocity of gases in the fluidized bed reactor in the downstream portion 206 of the main reactor vessel 250 may be 60% to 140%, from 70% to 130%, 80% to 120%, or even 90% to 110% of the superficial gas velocity in the fluidized bed reactor in the upstream portion 204 of the main reactor vessel. In additional embodiments, the surface velocity of gases in the fluidized bed reactor in the downstream portion 206 of the main reactor vessel 250, in the upstream portion 204 of the main reactor vessel 250, or both, may be less than or equal to 140% (such as, for example, less than or equal to 130%, less than or equal to 120%, less than or equal to 110%, less than or equal to 100%, less than or equal to 90% or even less than or equal to 80%) of the surface velocity of gases in the fluidized bed reactor in the central portion 208 of the main reactor vessel 250. For example, the surface velocity of gases in the fluidized bed reactor in the downstream portion 206 of the main reactor vessel 250, in the upstream portion 204 of the main reactor vessel 250, or both, may be 60% to 140%, 70% to 130%, 80% to 120%, or even 90% to 110% of the surface velocity of the gases in the reactor. fluidized bed in the central portion 208 of the main reactor vessel 250.

[0033] According to additional embodiments, the suspension density in the fluidized bed reactor in the downstream portion 206 of the main reactor vessel 250 may be greater than or equal to 25% (such as greater than or equal to 35%, greater than or equal to at 50%, or even greater than or equal to 75%), of the suspension density in the fluidized bed reactor in the upstream portion 204 of the main reactor vessel 250. For example, in additional embodiments, the suspension density in the fluidized bed reactor in the downstream portion 206 of the main reactor vessel 250 may be 25% to 175%, 50% to 150%, 80% to 120%, or even 90% to 110% of the suspension density in the bed reactor. fluidized in the upstream portion 204 of the main reactor vessel. In additional embodiments, the suspension density in the fluidized bed reactor in the central portion 208 of the main reactor vessel 250 may be greater than or equal to 40%, 50%, 60%, 70%, or even 80% of the suspension density in the fluidized bed reactor. fluidized bed reactor in the upstream portion 204 of the main reactor vessel 250.

[0034] As described herein, the surface velocity in the upstream portion 204 and the downstream portion 206 of the main reactor vessel 250 can be determined using known equations, such as the perfect gas law with measurable properties of the currents within the reactor. of fluidized bed 202. The temperature and pressure in the upstream portion 204 and the downstream portion 206 of the main reactor vessel 250, respectively, as well as the mass flow rates and gas compositions entering and leaving the main reactor vessel 250, can be used to determine the surface velocity in the upstream portion 204 and the downstream portion 206 of the main reactor vessel 250. For example, temperature and pressure probes can be used within the fluidized bed reactor and side streams at heights throughout the fluidized bed reactor can be determinants of the gas composition as a particular height. Additionally, the suspension density can be determined by comparing the pressure at two reactor heights and applying known equations. It should be understood that since two measurements may be necessary to determine the suspension density, the suspension density in the upstream portion 204 may be measured by data collected from the area adjacent to the distributor and one foot downstream (e.g., above) from the distributor. Likewise, the suspension density in the downstream portion 206 can be measured by data collected from the area adjacent to the transition section 258 and one foot upstream (e.g., below) the transition section 258.

[0035] In one or more embodiments, based on the shape, size, and other processing conditions, such as temperature and pressure, in the main reactor vessel 250 and the downstream reactor section 230, the main reactor vessel 250 may operate in a manner that is or approaches isothermal, such as in a fluidized bed, turbulent, or fast bubbling reactor, although the downstream reactor section 230 may operate in more than one obstruction flow manner, such as in a dilute phase riser reactor. For example, the fluidized bed reactor 202 of FIG. 1 may comprise a main reactor vessel 250 operating as a fast bubbling, turbulent or fluidized bed reactor and a downstream reactor section 230 operating as a dilute phase riser reactor, with the result that the flow of catalyst and of medium gas moves concomitantly upward. As the term is used herein, “average flow” refers to the net flow, that is, the total upward flow minus the retrograde or reverse flow, as is typical of the behavior of fluidized particles generally. As described herein, a “fast fluidized” reactor may refer to a reactor utilizing a fluidization regime in which the surface velocity of the gas phase is greater than the choke velocity and may be semi-dense in operation. As described herein, a “turbulent” reactor may refer to a fluidization regime in which the surface velocity is less than the choke velocity and is denser than the fast fluidized regime. As described herein, a “bubbling bed” reactor can refer to a fluidization regime in which well-defined bubbles in a highly dense bed are present in two distinct phases. “Choke speed” refers to the minimum speed required to maintain solids in dilute phase mode in a vertical conveying line. As described herein, a “dilute phase riser” may refer to a riser reactor operating at transport velocity, wherein the gas and catalyst have approximately the same velocity in a dilute phase.

[0036] In one or more embodiments, the pressure in the fluidized bed reactor 202 can vary from 0.41 MPa to 0.31 MPa (6.0 to 44.7 pounds per square inch absolute) (psia, about 41 .4 kilopascals, (kPa) to about 308.2 kPa), but in some embodiments, a narrower range is selected, such as from 0.10 MPa to 0.24 MPa (15.0 psia to 35.0 psia) , (from about 103.4 kPa to about 241.3 kPa), can be employed. For example, the pressure may be from 0.10 MPa to 0.21 MPa (15.0 psia to 30.0 psia) (from about 103.4 kPa to about 206.8 kPa), from 0.12 MPa to 0.19 MPa (17.0 psia to 28.0 psia) (from about 117.2 kPa to about 193.1 kPa) or from 0.13 MPa to 0.17 MPa (19.0 psia to 25 .0 psia) (from about 131.0 kPa to about 172.4 kPa). Unit conversions from standard (non-SI) to metric (SI) expressions in this document include “about” to indicate rounding that may be present in metric (SI) expressions as a result of the conversions.

[0037] In additional embodiments, the weight hourly space velocity (WHSV) for the disclosed process can range from 12.6 mg/s to 12.6 g/s (0.1 pound (lb) to 100 lb) of product feed chemical per hour (h) per lb of catalyst in the reactor (lb of feed/h/lb of catalyst). For example, when a reactor comprises a main reactor section 250 that operates as a fast bubbling, turbulent, or fluidized bed reactor and a downstream reactor section 230 that operates as a riser reactor, the surface gas velocity may vary. from 2 feet per second (ft/s, about 0.61 meter per second, m/s) to 80 ft/s (about 24.38 m/s), such as from 2 ft/s (about 0 .61 m/s) to 10 ft/s (about 3.05 m/s) in the main reactor vessel 250 and from 30 ft/s (about 9.14 m/s) to 70 ft/s ( about 21.31 m/s) in the downstream reactor section 230. In additional embodiments, a reactor configuration that is completely of a riser type may operate at a single high surface gas velocity, e.g., in some modalities at least 30 ft/s (about 9.15 m/s) entirely.

[0038] In additional embodiments, the ratio of catalyst to feed stream in the fluidized bed reactor 202 can range from 5 to 100 on a weight-to-weight (w/w) basis. In some embodiments, the ratio may vary from 10 to 40, such as 12 to 36 or 12 to 24.

[0039] In additional embodiments, the catalyst flow can be from 1 pound per square foot-second (lb/ft2-s) (about 4.89 kg/m2-s) to 20 lb/ft2-s (about of 97.7 kg/m2-s) in the main reactor vessel 250, and from 10 lb/ft2-s (about 48.9 kg/m2-s) to 100 lb/ft2-s (about 489 kg/m2-s) m2-s) in the downstream reactor section 230.

[0040] According to additional embodiments, the fluidized bed reactor 202 may include internal structures, such as those described in US Publication 2016/0375419, the contents of which are incorporated by reference in their entirety.

[0041] Now referring to FIG. 3, an exemplary reactor system 102 that may incorporate a fluidized bed reactor (such as that of FIG. 1 or FIG. 2) and be suitable for use with the methods described herein is represented schematically. It should be understood that the system of FIG. 3 is just an example system and other systems can be used with the fluidized bed reactors described here.

[0042] The reactor system 102 generally comprises multiple system components, such as a reactor portion 200 and/or a catalyst processing portion 300. As used herein in the context of FIG. 2, reactor portion 200 generally refers to the portion of a reactor system 102 in which the main process reaction occurs, such as a dehydrogenation reaction, a cracking reaction, a dehydration reaction, or a methanol to olefin reaction. , for example, to form light olefins. The reactor portion 200 comprises a fluidized bed reactor 202 that may include a downstream reactor section 230 and a main reactor vessel 250. In accordance with one or more embodiments, as depicted in FIG. 3, the reactor portion 200 may additionally include a catalyst separation section 210 that serves to separate the catalyst from chemicals formed in the fluidized bed reactor 202. Additionally, as used herein, the catalyst processing portion 300 refers generally to that portion of a reactor system 102 where the catalyst is processed in some way, such as by combustion. The catalyst processing portion 300 may comprise a combustor 350 and a riser 330 and may optionally comprise a catalyst separation section 310. In some embodiments, the catalyst may be regenerated by burning contaminants such as coke in the catalyst processing portion 300. In additional embodiments, the catalyst may be heated in the catalyst processing portion 300. A supplemental fuel may be used to heat the catalyst in the catalyst processing portion 300 if coke or other combustible material is not formed in the catalyst or an amount of coke formed in the catalyst is not enough to burn to heat the catalyst to a desired temperature. In one or more embodiments, the catalyst separation section 210 may be in fluid communication with the combustor 350 (e.g., via standpipe 426) and the catalyst separation section 310 may be in fluid communication with the combustion vessel. main reactor 250 (e.g., via standpipe 424 and transport riser 430).

[0043] As described with respect to FIG. 3, the feed stream may enter a transport riser 430 and the product stream may exit the reactor system 102 via tube 420. According to one or more embodiments, the reactor system 102 may be operated by feeding a feed of chemical (e.g., in a feed stream) and a fluidized catalyst to the main reactor vessel 250. The chemical feed contacts the catalyst in the main reactor vessel 250 and each flows up and through the feed section. downstream reactor 230 to produce a chemical. The chemical and catalyst may be passed out of the downstream reactor section 230 to a separation device 220 in the catalyst separation section 210, where the catalyst is separated from the chemical, which is conveyed out of the separation section. of catalyst 210. The separated catalyst is passed from the catalyst separation section 210 to the combustor 350. In the combustor 350, the catalyst can be processed, for example, by combustion. For example, and without limitation, the catalyst may be decoked and/or supplemental fuel may be burned to heat the catalyst. Next, the catalyst is passed out of the combustor 350 and through the riser 330 to a riser termination separator 378, where the gas and solid components of the riser 330 are at least partially separated. The remaining vapor and solids are transported to a secondary separation device 320 in the catalyst separation section 310 where the remaining catalyst is separated from the catalyst processing gases (e.g., gases emitted by the combustion of spent catalyst or supplemental fuel). The separated catalyst is then passed from the catalyst separation section 310 (via portion 312) to the main reactor vessel 250 via standpipe 424 and a transport riser 430, where it is further utilized in a catalytic reaction. Thus, the catalyst, in operation, may cycle between the reactor portion 200 and the catalyst processing portion 300. In general, the processed chemical streams, including the feed streams and product streams, may be gaseous, and the catalyst may be fluidized particulate solid.

[0044] The catalyst entering the main reactor vessel 250 via transport riser 430 may be passed through the vertical tube 424 to a transport riser 430, thereby reaching the catalyst processing portion 300. In some embodiments, the Catalyst may come directly from the catalyst separation section 210 via standpipe 422 and to a transport riser 430, where it enters the main reactor vessel 250. This catalyst may be deactivated slightly, but may still, in some embodiments, be suitable for reaction in the main reactor vessel 250. As used herein, “deactivated” may refer to a catalyst that is contaminated with a substance, such as coke, or is cooler in temperature than desired. Regeneration can move contaminant such as coke, raise the catalyst temperature, or both.

[0045] In operation, the catalyst may move upward through the downstream reactor section 230 (from the main reactor vessel 250) and to the separation device 220. In some embodiments, the downstream reactor section 230 may comprise an inner portion 234 (i.e., within the catalyst separation section 210) and an outer portion 232. The separated vapors may be removed from the reactor system 102 via a tube 420 into a gas outlet port 216 of the separation section. of catalyst 210. According to one or more embodiments, the separation device 220 may be a cyclonic separation system, which may include two or more cyclonic separation stages. In embodiments in which the separation device 220 comprises more than one cyclonic separation stage, the first separation device into which the fluidized stream enters is called a primary cyclonic separation device. The fluidized effluent from the primary cyclonic separation device may enter a secondary cyclonic separation device for further separation. Primary cyclonic separation devices may include, for example, primary cyclones and systems commercially available under the names VSS (commercially available from UOP), LD2 (commercially available from Stone and Webster) and RS2 (commercially available from Stone and Webster). Primary cyclones are described, for example, in US Patents 4,579,716; 5,190,650 and 5,275,641, which are each incorporated by reference in their entirety in this document. In some separation systems that utilize primary cyclones as the primary cyclonic separation device, one or more sets of additional cyclones, e.g., secondary cyclones and tertiary cyclones, are employed for further separation of the catalyst from the product gas. It should be understood that any primary cyclonic separation device can be used in embodiments of the invention.

[0046] According to one or more embodiments, following the separation of vapors in the separation device 220, the catalyst may generally move through the separator 224 to the catalyst outlet port 222 where the catalyst is transferred out of the reactor 200 via standpipe 426 and to the catalyst processing portion 300. Optionally, the catalyst may also be transferred directly back to the main reactor vessel 250 via standpipe 422. Alternatively, the catalyst may be pre-mixed with the catalyst processed in transport riser 430.

[0047] According to one or more embodiments, the operation of the chemical process, such as in the reactor system 102, may comprise recycling the catalyst used in the chemical process by passing the catalyst from the fluidized bed reactor 202 to a regeneration unit (such such as the combustor 350 of the embodiment of FIG. 2), process the respective catalyst in the regeneration unit and pass the first catalyst from the regeneration unit to the fluidized bed reactor 202.

[0048] Referring now to the catalyst processing portion 300, as depicted in FIG. 3, the combustor 350 of the catalyst processing portion 300 may include one or more lower reactor section inlet ports 352 and may be in fluid communication with the riser 330. The combustor 350 may be in fluid communication with the catalyst separation section 210 through vertical tube 426 which can feed spent catalyst from the reactor portion 200 to the catalyst processing portion 300 for regeneration. The combustor 350 may include an additional lower reactor section inlet port 352 where the air inlet 428 connects to the combustor 350. The air inlet 428 may supply reactive gases that can react with the spent catalyst or a supplemental fuel to regenerate. at least partially the catalyst. For example, the catalyst may be coked after reactions in the main reactor vessel 250, and the coke may be removed from the catalyst (i.e., regenerating the catalyst) by a combustion reaction. For example, oxidizer (such as air) may be fed to the combustor 350 via the air inlet 428. Alternatively or additionally, such as when coke is not formed in the catalyst, a supplemental fuel may be injected into the combustor 350, which may be burned to heat the catalyst. Following combustion, the processed catalyst may be separated in the catalyst separation section 310 and supplied back to the reactor portion 200 via standpipe 424.

EXAMPLES

[0049] The following examples are illustrative in nature and should not serve to limit the scope of the present application.

[0050] A model was constructed to calculate expected suspension density, conversion and surface gas velocity in a fluidized bed reactor as a function of reactor geometry. The fluidized bed reactors had geometry similar to that in FIG. 1 or FIG. 2, but with specified tapering of the main reactor vessel. Specifically, suspension density, conversion, and surface gas velocity were calculated as a function of height for varying reactor geometries with externally tapering walls. Calculations for hydrodynamics were based on the methods disclosed in Kunii, D., and Levenspiel, O., Entrainment of solids from fluidized beds, Powder Technology, 61, 1990, 193-206. The model simulated a reaction in which two product gas molecules were formed for each reactant gas molecule. The gas velocity at the bottom of the reactor was 1.07 m/s (3.5 ft/s).

[0051] In a first tested embodiment (a comparative example), a constant reactor diameter was tested. Lines 502 in FIGS. 4A, 4B and 4C represent suspension density, conversion and surface gas velocity, respectively, as a function of reactor height. FIG 4D represents at line 502 the constant diameter of the main reactor vessel. The results showed that, with constant diameter, the suspension density was significantly reduced at high heights, while the surface gas velocity was significantly increased at increasing heights.

[0052] A second tested embodiment is represented as line 504 in FIGS 4A, 4B, 4C and 4D. In this embodiment, the geometry of the main reactor vessel allows constant surface gas velocity as a function of reactor height. In such a configuration, the suspension density remains higher at all heights compared to the constant diameter comparative example. The geometric profile of the main reactor vessel can be seen in FIG. 4D for such an embodiment, in which the slope of the profile increases with increasing height and the upper half of the main reactor vessel is almost cylindrical.

[0053] A third tested embodiment is represented as line 506 in FIGS 4A, 4B, 4C and 4D. In this embodiment, the geometry of the main reactor vessel is linear, where the diameter in the downstream portion of the main reactor vessel is the same as that of the second tested embodiment. In such a configuration, the suspension density and surface gas velocity are both more desirable than in the comparative example.

[0054] A fourth tested modality is represented as line 508 in FIGS 4A, 4B, 4C and 4D. In this embodiment, the geometry of the main reactor vessel was linear like the third example embodiment, but was wider in the downstream portion, so that 0.5 conversion could be achieved. This embodiment also increased the suspension density and reduced the surface gas velocity compared to the comparative example.

[0055] The residence time and average density for the first, second, third and fourth example modalities were calculated and are represented in Table 1 below. Table 1:

[0056] As shown in FIG. 4B, reactor designs with tapered geometry have higher conversion at lower heights. Therefore, it is contemplated that the tapered geometry designs disclosed herein may be used to construct and operate reactors that are shorter than conventional reactors (relative to overall feed rate). Additionally, without being bound by theory, it is believed that the shorter reactor may result in a reduced residence time, which may result in higher selectivity for dehydrogenation reactions due to reduced thermal cracking reactions.

[0057] It will be evident to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Since modifications, combinations, subcombinations and variations of the disclosed embodiments embodying the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed as including everything within the scope of the appended claims and their equivalents.

Claims (14)

1. Method for converting a reactant gas, the method characterized by the fact that it comprises: - introducing the reactant gas into a fluidized bed reactor (202), so that the reactant gas is contacted by a catalyst, the bed reactor being fluidized vessel (202) comprises a main reactor vessel comprising an upstream portion (204) and a downstream portion (206), and a transition section (258) connected to the downstream portion (206) of the main reactor vessel (250 ), and wherein the reactant gas enters the fluidized bed reactor (202) at or near the upstream portion (204) of the main reactor vessel, and wherein the transition section (258) projects internally from the vessel from the main reactor (250) to a riser (230); - catalytically reacting the reactant gas to form a reaction product in the fluidized bed reactor (202), wherein the reaction results in additional gas molecules in relation to the reactant gas; and - passing the reaction product and any unreacted reactant gas through the transition section (258), and into the riser tube (230), the riser tube (230) being connected to the transition section (258); wherein the main reactor vessel is tapered such that the upstream portion (204) of the main reactor vessel (250) comprises a smaller cross-sectional area than the downstream portion (206) of the main reactor vessel (250). ). 2. Method according to claim 1, characterized in that the surface velocity of the gases in the fluidized bed reactor (202) in the downstream portion (206) of the main reactor vessel (250) is less than or equal to 140 % of the surface velocity of the gases in the fluidized bed reactor (202) in the upstream portion (204) of the main reactor vessel (250). 3. Method according to claim 1, characterized in that the suspension density in the fluidized bed reactor (202) in the downstream portion (206) of the main reactor vessel (250) is greater than or equal to 25% of the suspension density of gases in the fluidized bed reactor (202) in the upstream portion (204) of the main reactor vessel (250). 4. Method according to claim 1, characterized in that the reaction product is a dehydrogenation product of the reactant gas. 5. Method according to claim 4, characterized in that the reactant gas comprises one or more of ethane, propane, n-butane, isobutane and ethylbenzene. 6. Method according to claim 1, characterized in that the main reactor vessel (250) comprises a central portion between the downstream portion (206) and the upstream portion (204), and wherein the superficial velocity of the gases in the fluidized bed reactor (202) in the central portion of the main reactor vessel (250) is 60% to 140% of the surface velocity of the gases in the fluidized bed reactor (202) in the upstream portion (204) of the vessel of main reactor (250). 7. Method according to claim 1, characterized in that the main reactor vessel (250) comprises a central portion between the downstream portion (206) and the upstream portion (204), and in which the superficial velocity of the gases in the fluidized bed reactor (202) in the central portion of the main reactor vessel (250) is 80% to 120% of the surface velocity of the gases in the fluidized bed reactor (202) in the upstream portion (204) of the vessel of main reactor (250). 8. Method according to claim 1, characterized in that the surface velocity of the gases in the fluidized bed reactor (202) in the downstream portion (206) of the main reactor vessel (250) is 80 to 120% of the surface velocity of gases in the fluidized bed reactor (202) in the upstream portion (204) of the main reactor vessel (250). 9. Method according to claim 1, characterized in that the main reactor vessel (250) comprises a slope that is substantially constant. 10. The method of claim 1, wherein the main reactor vessel (250) comprises a slope that is less at or near the downstream portion (206) than at or near the upstream portion ( 204). 11. Method according to claim 1, characterized in that the main reactor vessel (250) comprises a central portion between the downstream portion (206) and the upstream portion (204), and wherein an area of cross-section of the central portion is smaller than the cross-sectional area of the downstream portion (206) and larger than the cross-sectional area of the upstream portion (204). 12. Method according to claim 1, characterized in that the surface velocity of the gases in the fluidized bed reactor (202) in the downstream portion (206) of the main reactor vessel (250) is less than or equal to 140 % of the surface velocity of the gases in the fluidized bed reactor (202) in the upstream portion (204) of the main reactor vessel (250), or the suspension density in the fluidized bed reactor (202) in the downstream portion (206) of the main reactor vessel (250) is greater than or equal to 25% of the suspension density of the gases in the fluidized bed reactor (202) in the upstream portion (204) of the main reactor vessel (250), or both. 13. Method according to claim 12, characterized in that the reaction product is a dehydrogenation product of the reactant gas. 14. Method according to claim 13, characterized in that the reactant gas comprises one or more of ethane, propane, n-butane, isobutane and ethylbenzene.