Patent Description:
<CIT> relates to a method for catalytically cracking a petroleum hydrocarbon feed stock which comprises the steps of forming a disperse phase suspension of a finely divided cracking catalyst in a vaporized hydrocarbon feed stock at a temperature within the range of about <NUM> (<NUM>) and <NUM> (<NUM> F), flowing said suspension at a pressure within the range of about <NUM> to <NUM> MPa (<NUM> p. ) upwardly through a conically diverging reaction zone having a length-to-average diameter ratio within the range of about <NUM>:<NUM> to about <NUM>:<NUM> and an angle of divergence of about <NUM> (<NUM>') to <NUM> (<NUM>') at an inlet superficial velocity within the range of about <NUM> (<NUM>) to <NUM> meter per second (<NUM> feet per second) and an outlet superficial gas velocity within the range of about <NUM> (<NUM>) and <NUM> meter per second (<NUM> feet per second), maintaining a sufficient amount of catalyst in said suspension to provide in said reaction zone a weight ratio of feed per hour to catalyst within the range of about <NUM>:<NUM> to about <NUM>:<NUM> and a catalyst to oil ratio within the range of about <NUM>:<NUM> to <NUM>:<NUM> to catalytically crack said hydrocarbon feed stock to form desired hydrocarbon products, separating said hydrocarbon products from said catalyst by momentarily accelerating said suspension and then discharging said suspension only laterally and downwardly from the upper end of said conical reaction zone whereby said outlet superficial gas velocity is rapidly decelerated and the accelerated velocity of the catalyst is reduced by about <NUM> to <NUM> percent, collecting said separated catalyst exteriorly of said conical reaction zone, and thereafter injecting an additional quantity of vaporized hydrocarbon feed stock into said collected catalyst in an amount sufficient to form a dense phase suspension of said collected catalyst in said additionally injected feed stock to catalytically crack at least a portion of said additionally injected hydrocarbon feed stock.

<CIT> relates to a gas-solid reactor comprising at least one catalyst containment zone, at least one first reaction zone operating in dense or fast mode, means for supplying a primary feed to said at least one first reaction zone, at least one second reaction zone operating in transported mode, and a primary gas-solid separator wherein said second reaction zone is directly connected to said primary gas-solid separator, said primary separator comprising a series of separation chambers and stripping chambers, said separation and stripping chambers being disposed alternately around the sidewalls of said second reaction zone, each of the separation chambers communicating with said second reaction zone, via openings provided in the side walls of the second reaction zone, each of said separation chambers comprises a rounded upper wall and a substantially parallel deflector which separate, by the centrifugal effect, solid particles and largely dedusted gas, wherein said separation chamber has a lower portion which receives the separated solid particles, and said lower portion of the separation chamber is connected to a stripping zone via openings, and wherein each of said stripping chambers communicating with a separation chamber via an opening cut in the vertical wall of the separation chamber at a level located beneath the deflector, through which said largely dedusted gas is introduced into the stripping chambers, and said stripping chambers having lower portions which communicate with said stripping zone, and said stripping chambers having upper portions that communicate via line with at least one secondary gas-solid separation system.

Many reactions utilizing gas streams as reactants form additional moles of gas as a result of the reaction (i.e., when more molecules of gas exist after reaction than before). For example, dehydrogenation and cracking reactions produce additional moles of product compared to that which existed in the reactant stream. When the reactant and product are gases, changes in local gas velocities may result in the reactor by the formation of these additional molecules.

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

More specifically, it has been found that the formation of excess gas molecules following reaction with respect to the amount of gas of the feed reactant may cause increases in the gas superficial velocity and decreases to the suspension density of contents of the reactor. As used herein, "suspension density" refers to the density calculated from both solids contents (e.g., catalyst) and gas contents (e.g., gaseous reactants and products) in the reactor. For example, as more gas is produced through reaction, the superficial velocity of gases may increase, sometimes drastically, in a fluidized bed reactor. Additionally the suspension density (including the reactant and product gas and solid particulate catalyst) may decrease such that conversion is decreased due to lack of catalyst with respect to reactant gas. Since conversion is negatively affected, reactor volume may need to be increased, adding undesirable capital costs. Additionally, high gas velocity in the reactor can make it difficult to control the amount of catalyst in the system at a given time.

In order to mitigate or entirely 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 may be utilized for gas-based reactions which produce excess gas molecules. For example, a fluidized bed reactor which is more narrow in its upstream portion than its downstream portion may allow for relatively constant gas superficial velocity, suspension density, or both, in the upstream and downstream portions of the fluidized bed reactor. By contrast, conventional fluidized bed reactors with tubular shapes generally have increased gas velocity as a function of height. Proper design of the geometry to the fluidized bed reactor, such as a tapered geometry, can allow for reduced increases in gas velocity and/or losses in suspension density as the reaction progresses in downstream portions of the reactor. That is, as the reaction occurs along the height of the reactor (assuming reaction products are moving upwardly), the increase in cross-sectional area compensates for the increase in gas volume and therefore may maintain relatively constant gas velocity. The relative stability of the gas velocity, the suspension density, or both, may allow for mitigation of the problems discussed hereinabove.

According to one or more embodiments, a reactant gas is converted by a method comprising introducing the reactant gas to a fluidized bed reactor such that the reactant gas is contacted by a catalyst,
wherein the fluidized bed reactor comprises 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 and wherein the reactant gas enters the fluidized bed reactor at the upstream portion of the main reactor vessel, and wherein the transition section projects inwardly from the main reactor vessel to a riser; catalytically reacting the reactant gas to form a reaction product in the fluidized bed reactor, wherein the reaction results in additional gas molecules relative to the reactant gas; and passing the reaction product and any unreacted reactant gas through the transition section and into the riser, wherein the riser is connected to the transition section; wherein the main reactor vessel is tapered such that the upstream portion of the main reactor vessel comprises a lesser cross-section area than the downstream portion of the main reactor vessel. The main reactor vessel may be tapered such that the upstream portion of the main reactor vessel comprises a lesser cross-sectional area than the downstream portion of the main reactor vessel such that the superficial velocity of the gases in the fluidized bed reactor at the downstream portion of the main reactor vessel may be less than or equal to <NUM>% of the superficial velocity of the gases in the fluidized bed reactor at the upstream portion of the main reactor vessel. The main reactor vessel may be tapered such that the upstream portion of the main reactor vessel comprises a lesser cross-section area than the downstream portion of the main reactor vessel such that the suspension density in the fluidized bed reactor at the downstream portion of the main reactor vessel may be greater than or equal to <NUM>% of the suspension density in the fluidized bed reactor at the upstream portion of the main reactor vessel.

It is to be understood that both the foregoing brief summary and the following detailed description present embodiments of the technology, and are intended to provide an overview or framework for understanding the nature and character of the technology as it is claimed. The accompanying drawings are included to provide a further understanding of the technology, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments and, together with the description, serve to explain the principles and operations of the technology. Additionally, the drawings and descriptions are meant to be merely illustrative, and are not intended to limit the scope of the claims in any manner.

Additional features and advantages of the technology disclosed herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the technology as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

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 the like. It would be known that these components are within the spirit and scope of the present embodiments disclosed. However, operational components, such as those described in the present disclosure, may be added to the embodiments described in this disclosure.

Embodiments related to methods for processing chemical streams in fluidized bed reactor are described herein. 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 which 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 conversion of the feed stream is incomplete, which may be typical of many chemical reactions.

The systems and apparatuses described herein, such as the fluidized bed reactors described herein, may be utilized as processing equipment for various fluidized catalytic reactions. The methods and apparatuses described may be utilized in reactions wherein a gaseous feed is converted to a gaseous product stream by contact with a solid state catalyst, such as a particulate catalyst. For example, hydrocarbons, as well as other chemical feedstocks, can be converted into desirable products through 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, polymerization of ethylene, dehydration of hydrocarbons to form light olefins, and some methanol to olefin (MTO) reactions.

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 with respect to the moles of feed gas molecules. When the products are gaseous, the local pressure in the reactor may be increased as the reaction progresses. Such reactions, in some embodiments, may be represented by the formula aR → bP + cZ, where R represented the reactant species, P represented the product species, Z represents another product species, and a, b, and c each represent the relative amount of each species utilized 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 are the reactions for which the presently described methods are apparatuses may be directed. As such, these reaction forms two or more product molecules from each reactant molecule which is reacted. It is noted that the above equation is only one example chemical reaction, and it should be understood that other reactions are within the scope of this disclosure, such as those where two or more products and/or reactants are present.

According to some embodiments, the fluidized bed reactors described herein may process reactant gas comprising ethane, propane, n-butane, isobutane, and ethylbenzene (for example, at least <NUM> wt. %, <NUM> wt. %, <NUM> wt. %, or even <NUM> wt. % of any of these reactant gases, or combinations thereof) to form product gas comprising ethene, propene, butene isomers and butadiene, isobutene, styrene, or combinations thereof (for example, at least at least <NUM> wt%, at least <NUM> wt. %, at least <NUM> wt. %, at least <NUM> wt. %, at least <NUM> wt. %, at least <NUM> wt. % or even at least <NUM> wt. % of any of these product gases, or combinations thereof). For example, gases suitable for dehydrogenation are contemplated herein.

Now referring to <FIG>, an embodiment of a fluidized bed reactor is depicted, which may process a feed stream by contact with a solid catalyst. According to one or more embodiments described herein, the fluidized bed reactor <NUM> comprises a main reactor vessel <NUM>, a transition section <NUM>, and a downstream reactor section <NUM>, such as a riser. The transition section <NUM> connects the main reactor vessel <NUM> with the downstream reactor section <NUM>. As depicted in <FIG>, the main reactor vessel <NUM> may be positioned below the downstream reactor section <NUM>. Such a configuration may be referred to as an upflow configuration in the fluidized bed reactor <NUM>. A transport riser <NUM> may supply one or more of reactant gas and catalyst to the fluidized bed reactor <NUM>, and the gaseous reactants and products, as well as the catalyst, may move through a feed distributor <NUM>, through the main reactor vessel <NUM>, through the transition section <NUM>, and into and through the downstream reactor section <NUM>. As depicted in <FIG>, the movement of the catalyst and product and reactant gases is upward (depicted by the x-axis). As described herein, "superficial velocity" refers to the superficial velocity of a material in the direction of overall material flow (through the plane perpendicular to the x-axis).

As described herein, the main reactor vessel <NUM> 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 <NUM> may have a substantially circular cross-sectional shape (which is representative of the cross-sectional view of <FIG>). Alternatively, the main reactor vessel <NUM> may be non-circular in cross-section. For example, the main reactor vessel <NUM> 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 <NUM>, as used throughout this disclosure, may generally include a metallic frame, and may additionally include refractory linings or other materials utilized to protect the metallic frame and/or control process conditions. As depicted in <FIG>, the main reactor vessel <NUM> may include a lower reactor portion catalyst inlet port <NUM> defining the connection of transport riser <NUM> to the main reactor vessel <NUM>.

The main reactor vessel <NUM> may be connected to a transport riser <NUM> which, in operation, may provide processed catalyst and/or reactant chemicals in a feed stream. The processed catalyst and/or reactant chemicals may be mixed with a feed distributor <NUM> housed in the main reactor vessel <NUM>. In one or more embodiments, the feed distributor <NUM> may be operable to dispense the first feed stream and the second feed stream at all shroud distributor velocities from <NUM>/s (<NUM> ft/s) to <NUM>/s (<NUM> ft/s). In such embodiments, various feed streams may be utilized while maintaining the desired reactor characteristics, such as operating as a fast fluidized, turbulent, or bubbling bed reactor in the main reactor vessel <NUM> and as a dilute phase riser reactor in the downstream reactor section <NUM>. For example, according to one or more embodiments, a shroud distributor velocity of about <NUM>/s (<NUM> ft/s) may be utilized in the main reactor vessel <NUM> for naphtha feeds, while a shroud distributor velocity of about <NUM>/s (<NUM> ft/s) may be utilized in the main reactor vessel <NUM> for propane feeds. In additional embodiments, some orifices could be closed in the fluidized bed reactor <NUM> when naphtha is utilized as a feed stream. The "shroud distributor velocity" refers the velocity at which the gas exits the distributor, sometimes through a shroud. For example, suitable distributors are disclosed in <CIT>.

As depicted in <FIG>, the main reactor vessel <NUM> is connected to the downstream reactor section <NUM> via the transition section <NUM>. The transition section <NUM> is tapered from the size of the cross-section of the main reactor vessel <NUM> to the size of the cross-section of the downstream reactor section <NUM> such that the transition section <NUM> projects inwardly from the main reactor vessel <NUM> to the downstream reactor section <NUM>.

In one or more embodiments, the downstream reactor section <NUM> may be generally cylindrical in shape (i.e., having a substantially circular cross-sectional shape), or may alternately be non-cylindrically shaped, such as prism shaped 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 <NUM>, as used throughout this disclosure, may generally include a metallic frame, and may additionally include refractory linings or other materials utilized to protect the metallic frame and/or control process conditions.

In some embodiments, such as those where the main reactor vessel <NUM> and the downstream reactor section <NUM> have similar cross-sectional shapes, the transition section <NUM> may be shaped as a frustum. For example, for an embodiment of a reactor portion <NUM> comprising a circular cross-sectioned main reactor vessel <NUM> and cylindrical downstream reactor section <NUM>, the transition section <NUM> may be shaped as a conical frustum. However, it should be understood that a wide variety of main reactor vessel <NUM> shapes are contemplated herein which connect various shapes and sizes of transition sections <NUM> and downstream reactor sections <NUM>.

According to one or more embodiments, the main reactor vessel <NUM> may be tapered outwardly with respect to the direction of general flow of materials (i.e., the direction of the x-axis) in the fluidized bed reactor <NUM>. For example, <FIG> depicts a linearly expanding main reactor vessel <NUM>, which has the shape of a segment of a cone. While the tapered geometry may be linear in some embodiments, some embodiments disclosed herein are not linearly tapered, such as that depicted in <FIG>.

Referring to <FIG>, the main reactor vessel <NUM> comprises an upstream portion <NUM> and a downstream portion <NUM>. The upstream portion <NUM> may be the portion of the main reactor vessel <NUM> adjacent the feed distributor <NUM> and the downstream portion <NUM> may be the portion of the main reactor vessel <NUM> adjacent the transition section <NUM>. A central portion <NUM> of the main reactor vessel <NUM> may be positioned equidistant between the upstream portion <NUM> and the downstream portion <NUM> (based on the height in the x-direction of the main reactor vessel <NUM>). The upstream portion <NUM> of the main reactor vessel <NUM> has a lesser cross-sectional area than the downstream portion <NUM> of the main reactor vessel <NUM>, defining a taper in the cross-sectional geometry of the main reactor vessel <NUM>. As described herein, unless otherwise explicitly stated, the "cross-sectional area" refers to the area of the cross section of a portion of the reactor part in a plane substantially orthogonal to the direction of average flow of reactants and/or products (i.e., the plane perpendicular to the x-axis in <FIG>). For example, in <FIG>, the cross sectional area of the main reactor vessel <NUM>, the transition section <NUM>, and the downstream reactor section <NUM>, or any portion of each, is in the direction
of a plane defined by the horizontal direction and the direction into the page (orthogonal to the direction of fluid motion, i.e., vertically upward in <FIG>). In additional embodiments, the upstream portion <NUM> may have a lesser cross-sectional area than the central portion <NUM>, and the central portion <NUM> may have a lesser cross-sectional area than the downstream portion <NUM>. As such, in some embodiments, the cross-sectional area of the central portion <NUM> may be less than the cross-sectional area of the downstream portion <NUM> and greater than the cross-sectional area of the upstream portion <NUM>.

In one or more embodiments, the cross-sectional area of the downstream portion <NUM> of the main reactor vessel <NUM> may be from <NUM> to <NUM> times that of the upstream portion <NUM> of the main reactor vessel <NUM> (e.g., from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>). According to one or more embodiments, the main reactor vessel <NUM> may have a height of from <NUM> (<NUM> ft) to <NUM> (<NUM> ft) (e.g., from <NUM> (<NUM> ft) to <NUM> (<NUM> ft), from <NUM> (<NUM> ft) to <NUM> (<NUM> ft), from <NUM> (<NUM> ft) to <NUM> (<NUM> ft), from <NUM> (<NUM> ft) to <NUM> (<NUM> ft), or from <NUM> (<NUM> ft) to <NUM> (<NUM> ft)).

In one or more embodiments, the taper of the main reactor vessel <NUM> may be described by a slope at a particular portion of the main reactor vessel <NUM>. For example, the main reactor vessel <NUM> may have a measurable slope (i.e., half the width change divided by the height change) at the upstream portion <NUM>, the downstream portion <NUM>, and the central portion <NUM>. That is, a constant cross-sectional shape would have a slope of <NUM>. In the embodiment of <FIG>, the slope may be substantially constant across the main reactor vessel <NUM>, such as substantially constant with respect to the upstream portion <NUM>, the downstream portion <NUM>, and the central portion <NUM>. Such a substantially constant slope corresponds to a linear profile of the main reactor vessel <NUM>. In additional embodiments, such as that of <FIG>, the main reactor vessel <NUM> may comprise a slope that is less at or near the downstream portion <NUM> than at or near the upstream portion <NUM> of the main reactor vessel <NUM>. In such embodiments, the slope at the central portion <NUM> may be less than that of the upstream portion <NUM> and greater than that of the downstream portion <NUM>. As is explained in the Examples which follow, the slope and relative shape of the main reactor vessel <NUM> may affect the superficial gas velocity and/or the suspension density at local positioned within the main reactor vessel <NUM>.

As depicted in <FIG>, the inwardly tapered transition section <NUM> and outwardly tapered main reactor vessel <NUM> form a geometric configuration of the fluidized bed reactor <NUM> in which the portion of the fluidized bed reactor <NUM> with the largest cross-sectional area is at the point where the transition section <NUM> and main reactor vessel <NUM> are connected (i.e., at or near the downstream portion <NUM> of the main reactor vessel <NUM>). The downstream reactor section <NUM> may have a lesser cross-sectional area than the transition section <NUM> and the main reactor vessel <NUM>. In one or more embodiments, the downstream reactor section <NUM> may have a smaller cross-sectional area than the upstream portion <NUM> of the main reactor vessel <NUM>.

According to the embodiments described herein, at least one purpose of the outwardly tapered main reactor vessel <NUM> is its effect upon the gas superficial velocity and/or suspension density at local positions in the main reactor vessel <NUM>. It may be desirable to have relatively constant gas superficial velocity and/or suspension density along the height of the main reactor vessel <NUM>. For example, it may be desirable to have similar gas superficial velocity and/or suspension density at two or more of the upstream portion <NUM> as at the downstream portion <NUM> or central portion <NUM>.

According to one more embodiments, the superficial velocity of the gases in the fluidized bed reactor at the downstream portion <NUM> of the main reactor vessel <NUM> may be less than or equal to <NUM>% (such as, e.g., less than or equal to <NUM>%, less than or equal to <NUM>%, less than or equal to <NUM>%, less than or equal to <NUM>%, less than or equal to <NUM>%, or even less than or equal to <NUM>%) of the superficial velocity of the gases in the fluidized bed reactor at the upstream portion <NUM> of the main reactor vessel <NUM>. For example, in additional embodiments, the superficial velocity of the gases in the fluidized bed reactor at the downstream portion <NUM> of the main reactor vessel <NUM> may be from <NUM>% to <NUM>%, from <NUM>% to <NUM>%, from <NUM>% to <NUM>%, or even from <NUM>% to <NUM>% of the superficial velocity of the gases in the fluidized bed reactor at the upstream portion <NUM> of the main reactor vessel. In additional embodiments, the superficial velocity of the gases in the fluidized bed reactor at the downstream portion <NUM> of the main reactor vessel <NUM>, at the upstream portion <NUM> of the main reactor vessel <NUM>, or both, may be less than or equal to <NUM>% (such as, e.g., less than or equal to <NUM>%, less than or equal to <NUM>%, less than or equal to <NUM>%, less than or equal to <NUM>%, less than or equal to <NUM>%, or even less than or equal to <NUM>%) of the superficial velocity of the gases in the fluidized bed reactor at the central portion <NUM> of the main reactor vessel <NUM>. For example, the superficial velocity of the gases in the fluidized bed reactor at the downstream portion <NUM> of the main reactor vessel <NUM>, at the upstream portion <NUM> of the main reactor vessel <NUM>, or both, may be from <NUM>% to <NUM>%, from <NUM>% to <NUM>%, from <NUM>% to <NUM>%, or even from <NUM>% to <NUM>% of the superficial velocity of the gases in the fluidized bed reactor at the central portion <NUM> of the main reactor vessel <NUM>.

According to additional embodiments, the suspension density in the fluidized bed reactor at the downstream portion <NUM> of the main reactor vessel <NUM> may greater than or equal to <NUM>% (such as greater than or equal to <NUM>%, greater than or equal to <NUM>%, or even greater than or equal to be from <NUM>%) of the suspension density in the fluidized bed reactor at the upstream portion <NUM> of the main reactor vessel <NUM>. For example, in additional embodiments, the suspension density in the fluidized bed reactor at the downstream portion <NUM> of the main reactor vessel <NUM> may be from <NUM>% to <NUM>%, from <NUM>% to <NUM>%, from <NUM>% to <NUM>%, or even from <NUM>% to <NUM>% of the suspension density in the fluidized bed reactor at the upstream portion <NUM> of the main reactor vessel. In additional embodiments, the suspension density in the fluidized bed reactor at the central portion <NUM> of the main reactor vessel <NUM> may be from greater than or equal to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>% of the suspension density in the fluidized bed reactor at the upstream portion <NUM> of the main reactor vessel <NUM>.

As described herein, the superficial velocity at the upstream portion <NUM> and the downstream portion <NUM> of the main reactor vessel <NUM> may be determined by utilizing known equations such as the ideal gas law with measurable properties of the streams within the fluidized bed reactor <NUM>. The temperature and pressure at the upstream portion <NUM> and the downstream portion <NUM> of the main reactor vessel <NUM>, respectively, as well as the mass flowrates and gas compositions entering and exiting the main reactor vessel <NUM> may be utilized to determine the superficial velocity at the upstream portion <NUM> and the downstream portion <NUM> of the main reactor vessel <NUM>. For example, temperature and pressure probes may be used within the fluidized bed reactor and slip streams at heights along the fluidized bed reactor can be determinative of the gas composition as a particular height. Additionally, the suspension density may be determined by comparing the pressure at two reactor heights and applying known equations. It should be understood that since two measurements may be required to determine the suspension density, the suspension density at the upstream portion <NUM> may be measured by data collected from the area adjacent the distributor and one foot downstream of (e.g., above) the distributor. Similarly, the suspension density at the downstream portion <NUM> may be measured by data collected from the area adjacent the transition section <NUM> and one foot upstream of (e.g., below) the transition section <NUM>.

In one or more embodiments, based on the shape, size, and other processing conditions such as temperature and pressure in the main reactor vessel <NUM> and the downstream reactor section <NUM>, the main reactor vessel <NUM> may operate in a manner that is or approaches isothermal, such as in a fast fluidized, turbulent, or bubbling bed reactor, while the downstream reactor section <NUM> may operate in more of a plug flow manner, such as in a dilute phase riser reactor. For example, the fluidized bed reactor <NUM> of <FIG> may comprise a main reactor vessel <NUM> operating as a fast fluidized, turbulent, or bubbling bed reactor and a downstream reactor section <NUM> operating as a dilute phase riser reactor, with the result that the average catalyst and gas flow moves concurrently upward. As the term is used herein, "average flow" refers to the net flow, i.e., the total upward flow minus the retrograde or reverse flow, as is typical of the behavior of fluidized particles in general. As described herein, a "fast fluidized" reactor may refer to a reactor utilizing a fluidization regime wherein the superficial velocity of the gas phase is greater than the choking velocity and may be semi-dense in operation. As described herein, a "turbulent" reactor may refer to a fluidization regime where the superficial velocity of less than the choking velocity and is more dense than the fast fluidized regime. As described herein, a "bubbling bed" reactor may refer to a fluidization regime wherein well defined bubbles in a highly dense bed are present in two distinct phases. The "choking velocity" refers to the minimum velocity required to maintain solids in the 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, where the gas and catalyst have about the same velocity in a dilute phase.

In one or more embodiments, the pressure in the fluidized bed reactor <NUM> may range from about <NUM> kilopascals, kPa, to about <NUM> kPa (<NUM> to <NUM> pounds per square inch absolute (psia)), but in some embodiments, a narrower selected range, such as from about <NUM> kPa to about <NUM> kPa (<NUM> psia to <NUM> psia), may be employed. For example, the pressure may be from about <NUM> kPa to about <NUM> kPa (<NUM> psia to <NUM> psia), from about <NUM> kPa to about <NUM> kPa (<NUM> psia to <NUM> psia), or from about <NUM> kPa to about <NUM> kPa (<NUM> psia to <NUM> psia). Unit conversions from standard (non-SI) to metric (SI) expressions herein include "about" to indicate rounding that may be present in the metric (SI) expressions as a result of conversions.

In additional embodiments, the weight hourly space velocity (WHSV) for the disclosed process may range from <NUM> (<NUM> pound (lb)) to <NUM> (<NUM> lb) of chemical feed per hour (h) per kg (lb) of catalyst in the reactor (kg feed/h/kg catalyst) ((lb feed/h/lb catalyst)). For example, where a reactor comprises a main reactor vessel <NUM> that operates as a fast fluidized, turbulent, or bubbling bed reactor and a downstream
reactor section <NUM> that operates as a riser reactor, the superficial gas velocity may range therein from about <NUM> meters per second, m/s (<NUM> feet per second (ft/s)) to about <NUM>/s (<NUM> ft/s), such as from about <NUM>/s (<NUM> ft/s) to about <NUM>/s (<NUM> ft/s) in the main reactor vessel <NUM>, and from about <NUM>/s (<NUM> ft/s) to about <NUM>/s (<NUM> ft/s) in the downstream reactor section <NUM>. In additional embodiments, a reactor configuration that is fully of a riser type may operate at a single high superficial gas velocity, for example, in some embodiments at least about <NUM>/s (<NUM> ft/s) throughout.

In additional embodiments, the ratio of catalyst to feed stream in the fluidized bed reactor <NUM> may range from <NUM> to <NUM> on a weight to weight (w/w) basis. In some embodiments, the ratio may range from <NUM> to <NUM>, such as from <NUM> to <NUM>, or from <NUM> to <NUM>.

In additional embodiments, the catalyst flux may be from about <NUM>/m<NUM>-s (<NUM> pound per square foot-second (lb/ft<NUM>-s)) to about <NUM>/m<NUM>-s (<NUM> lb/ft<NUM>-s) in the main reactor vessel <NUM>, and from about <NUM>/m<NUM>-s (<NUM> lb/ft<NUM>-s) to about <NUM>/m<NUM>-s <NUM> lb/ft<NUM>-s) in the downstream reactor section <NUM>.

According to additional embodiments, the fluidized bed reactor <NUM> may include internal structures such as those described in <CIT>.

Now referring to <FIG>, an example reactor system <NUM> which may incorporate a fluidized bed reactor (such as that of <FIG>) and be suitable for use with the methods described herein is schematically depicted. It should be understood that the system of <FIG> is only an example system, and other systems may be utilized with the fluidized bed reactors described herein.

The reactor system <NUM> generally comprises multiple system components, such as a reactor portion <NUM> and/or a catalyst processing portion <NUM>. As used herein in the context of <FIG>, the reactor portion <NUM> generally refers to the portion of a reactor system <NUM> in which the major process reaction takes place, such as a dehydrogenation reaction, a cracking reaction, a dehydration reaction, or a methanol-to-olefin reaction to, for example, form light olefins. The reactor portion <NUM> comprises a fluidized bed reactor <NUM> which may include a downstream reactor section <NUM> and a main reactor vessel <NUM>. According to one or more embodiments, as depicted in <FIG>, the reactor portion <NUM> may additionally include a catalyst separation section
<NUM> which serves to separate the catalyst from the chemical products formed in the fluidized bed reactor <NUM>. Also, as used herein, the catalyst processing portion <NUM> generally refers to the portion of a reactor system <NUM> where the catalyst is in some way processed, such as by combustion. The catalyst processing portion <NUM> may comprise a combustor <NUM> and a riser <NUM>, and may optionally comprise a catalyst separation section <NUM>. In some embodiments, the catalyst may be regenerated by burning off contaminants like coke in the catalyst processing portion <NUM>. In additional embodiments, the catalyst may be heated in the catalyst processing portion <NUM>. A supplemental fuel may be utilized to heat the catalyst in the catalyst processing portion <NUM> if coke or another combustible material is not formed on the catalyst, or an amount of coke formed on the catalyst is not sufficient to burn off to heat the catalyst to a desired temperature. In one or more embodiments, the catalyst separation section <NUM> may be in fluid communication with the combustor <NUM> (e.g., via standpipe <NUM>) and the catalyst separation section <NUM> may be in fluid communication with the main reactor vessel <NUM> (e.g., via standpipe <NUM> and transport riser <NUM>).

As depicted with respect to <FIG>, the feed stream may enter a transport riser <NUM>, and the product stream may exit the reactor system <NUM> via pipe <NUM>. According to one or more embodiments, the reactor system <NUM> may be operated by feeding a chemical feed (e.g., in a feed stream) and a fluidized catalyst into the main reactor vessel <NUM>. The chemical feed contacts the catalyst in the main reactor vessel <NUM>, and each flow upwardly into and through the downstream reactor section <NUM> to produce a chemical product. The chemical product and the catalyst may be passed out of the downstream reactor section <NUM> to a separation device <NUM> in the catalyst separation section <NUM>, where the catalyst is separated from the chemical product, which is transported out of the catalyst separation section <NUM>. The separated catalyst is passed from the catalyst separation section <NUM> to the combustor <NUM>. In the combustor <NUM>, the catalyst may be processed by, for example, combustion. For example, and without limitation, the catalyst may be de-coked and/or supplemental fuel may be combusted to heat the catalyst. The catalyst is then passed out of the combustor <NUM> and through the riser <NUM> to a riser termination separator <NUM>, where the gas and solid components from the riser <NUM> are at least partially separated. The vapor and remaining solids are transported to a secondary separation device <NUM> in the catalyst separation section <NUM> where the remaining catalyst is separated from the gases from the catalyst processing (e.g., gases emitted by combustion of spent catalyst or supplemental fuel). The separated catalyst is then passed from the catalyst separation section <NUM> (via portion <NUM>) to the main reactor vessel <NUM> via standpipe <NUM> and transport riser <NUM>, where it is further utilized in a catalytic reaction. Thus, the catalyst, in operation, may cycle between the reactor portion <NUM> and the catalyst processing portion <NUM>. In general, the processed chemical streams, including the feed streams and product streams may be gaseous, and the catalyst may be fluidized particulate solid.

The catalyst entering the main reactor vessel <NUM> via transport riser <NUM> may be passed through standpipe <NUM> to a transport riser <NUM>, thus arriving from the catalyst processing portion <NUM>. In some embodiments, catalyst may come directly from the catalyst separation section <NUM> via standpipe <NUM> and into a transport riser <NUM>, where it enters the main reactor vessel <NUM>. This catalyst may be slightly deactivated, but may still, in some embodiments, be suitable for reaction in the main reactor vessel <NUM>. As used herein, "deactivated" may refer to a catalyst which is contaminated with a substance such as coke, or is cooler in temperature than desired. Regeneration may remove the contaminant such as coke, raise the temperature of the catalyst, or both.

In operation, the catalyst may move upward through the downstream reactor section <NUM> (from the main reactor vessel <NUM>), and into the separation device <NUM>. In some embodiments, the downstream reactor section <NUM> may comprise an internal portion <NUM> (i.e., within the catalyst separation section <NUM>) and an external portion <NUM>. The separated vapors may be removed from the reactor system <NUM> via a pipe <NUM> at a gas outlet port <NUM> of the catalyst separation section <NUM>. According to one or more embodiments, the separation device <NUM> may be a cyclonic separation system, which may include two or more stages of cyclonic separation. In embodiments where the separation device <NUM> comprises more than one cyclonic separation stages, the first separation device into which the fluidized stream enters is referred to a primary cyclonic separation device. The fluidized effluent from the primary cyclonic separation device may enter into 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 <CIT>; <CIT>; and <CIT>. In some separation systems utilizing primary cyclones as the primary cyclonic separation device, one or more set 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 may be used in embodiments of the invention.

According to one or more embodiments, following separation from vapors in the separation device <NUM>, the catalyst may generally move through the stripper <NUM> to the catalyst outlet port <NUM> where the catalyst is transferred out of the reactor portion <NUM> via standpipe <NUM> and into the catalyst processing portion <NUM>. Optionally, the catalyst may also be transferred directly back into the main reactor vessel <NUM> via standpipe <NUM>. Alternatively, the catalyst may be premixed with processed catalyst in the transport riser <NUM>.

According to one or more embodiments, operating the chemical process, such as in reactor system <NUM>, may comprise recycling the catalyst utilized in the chemical process by passing the catalyst from the fluidized bed reactor <NUM> to a regeneration unit (such as the combustor <NUM> of the embodiment of <FIG>), processing the respective catalyst in the regeneration unit, and passing the first catalyst from the regeneration unit to the fluidized bed reactor <NUM>.

Referring now to the catalyst processing portion <NUM>, as depicted in <FIG>, the combustor <NUM> of the catalyst processing portion <NUM> may include one or more lower reactor section inlet ports <NUM> and may be in fluid communication with the riser <NUM>. The combustor <NUM> may be in fluid communication with the catalyst separation section <NUM> via standpipe <NUM>, which may supply spent catalyst from the reactor portion <NUM> to the catalyst processing portion <NUM> for regeneration. The combustor <NUM> may include an additional lower reactor section inlet port <NUM> where air inlet <NUM> connects to the combustor <NUM>. The air inlet <NUM> may supply reactive gases which may react with the spent catalyst or a supplemental fuel to at least partially regenerate the catalyst. For example, the catalyst may be coked following the reactions in the main reactor vessel <NUM>, 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 into the combustor <NUM> via the air inlet <NUM>. Alternatively or additionally, such as when coke is not formed on the catalyst, a supplemental fuel may be injected into the combustor <NUM>, which may be burned to heat the catalyst. Following combustion, the processed catalyst may be separated in the catalyst separation section <NUM> and delivered back into the reactor portion <NUM> via standpipe <NUM>.

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

A model was constructed to calculate expected suspension density, conversion, and superficial gas velocity in a fluidized bed reactor as a function of reactor geometry. The fluidized bed reactors had geometry similar to that of <FIG>, but with specified tapering of the main reactor vessel. Specifically, the suspension density, conversion, and superficial gas velocity were calculated as a function of height for varying reactor geometries with outwardly tapering walls. Calculations for hydrodynamics were based on the methods disclosed in<NPL>. The model simulated a reaction where two molecules of product gas was formed per each molecule of reactant gas. The gas velocity at the bottom of the reactor was <NUM>/s (<NUM> ft/s).

In a first tested embodiment (a comparative example), a constant reactor diameter was tested. Lines <NUM> in <FIG> depict the suspension density, conversion, and superficial gas velocity respectively as a function of height of the reactor. <FIG> depicts in line <NUM> the constant diameter of the main reactor vessel. The results shown that with constant diameter, the suspension density was significantly reduced at increased heights while the superficial gas velocity was significantly increased at increasing heights.

A second tested embodiment is depicted as line <NUM> in <FIG>. In this embodiment, the geometry of the main reactor vessel allows for constant superficial gas velocity as a function of reactor height. In such a configuration, suspension density remains greater at all heights as compared to the constant diameter comparative example. The geometric profile of the main reactor vessel can be seen in <FIG> for such an embodiment, where slope of the profile increases with increasing height, and the upper half of the main reactor vessel is nearly cylindrical.

A third tested embodiment is depicted as line <NUM> in <FIG>. In this embodiment, the geometry of the main reactor vessel is linear, where the diameter at the downstream portion of the main reactor vessel is equal to that of the second tested embodiment. In such a configuration, suspension density and superficial gas velocity are both more desirable than in the comparative example.

A fourth tested embodiment is depicted as line <NUM> in <FIG>. In this embodiment, the geometry of the main reactor vessel was linear like the third example embodiment, but was wider at the downstream portion so that conversion of <NUM> could be achieved. This embodiment also increased suspension density and reduced superficial gas velocity as compared with the comparative example.

The residence time and average density for the first, second, third, and fourth example embodiments was calculated, and is depicted in Table <NUM>, below.

Claim 1:
A method for converting a reactant gas, the method comprising:
introducing the reactant gas to a fluidized bed reactor such that the reactant gas is contacted by a catalyst, wherein the fluidized bed reactor comprises 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, and wherein the reactant gas enters the fluidized bed reactor at the upstream portion of the main reactor vessel, and wherein the transition section projects inwardly from the main reactor vessel to a riser;
catalytically reacting the reactant gas to form a reaction product in the fluidized bed reactor, wherein the reaction results in additional gas molecules relative to the reactant gas; and
passing the reaction product and any unreacted reactant gas through the transition section and into the riser, wherein the riser is connected to the transition section;
wherein the main reactor vessel is tapered such that the upstream portion of the main reactor vessel comprises a lesser cross-sectional area than the downstream portion of the main reactor vessel.