Reactor system for dehydrogenation of saturated C3-C6 hydrocarbons

Abstract

A reactor system and method for the catalytic dehydrogenation of saturated C3-C6 hydrocarbons within a reactor placed within a reactor settler, where the reactor is open at its bottom and open to the settler, and the outlet riser of the reactor is not rigidly coupled to at least one downstream cyclone. This configuration allows the amount of catalyst within the reactor to be controlled by varying the catalyst level in a reactor settler external to the reactor, and allows the total catalyst retention amount and / or weight hourly space velocity (WHSV) to be controlled independently of the catalyst flow from the catalyst regenerator.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 17 / 829,818, filed on June 1, 2022, which is incorporated herein by reference. Technical field

[0003] The present invention relates to systems and methods for dehydrogenating saturated C3 - C6 hydrocarbons, and more particularly, to systems and methods for dehydrogenating saturated C3 - C6 hydrocarbons that have better control over catalyst residence time and gas residence time.

[0004] Background

[0005] Techniques and the required catalysts for carrying out dehydrogenation reactions of saturated hydrocarbons in FCC - type (fluid catalytic cracking) converters have been developed. In this discussion, the term "Cx" will be used as a representative molecule of saturated hydrocarbons in subsequent discussions. For example, in one non - limiting embodiment, Cx refers to all C3 to C6 molecules, i.e., propane (C3), butane (C4), pentane (C5), and hexane (C6).

[0006] In a conventional FCC - type reactor design, the reaction occurs in a dilute - phase fluidized riser where the residence time is generally 2 - 3 seconds and the gas velocity is in the range of about 45 - 60 feet per second. In a typical riser design, the WHSV (weight hourly space velocity, which is the ratio of the feed mass flow rate to the catalyst mass in the reactor) is very high, generally greater than 50 hours -1 . One non - limiting embodiment of this type of FCC - type reactor design is KBR's ORTHOFLOW TM FCC.

[0007] Although the concept of WHSV is typically used for fixed - bed reactors where a fixed amount of catalyst is loaded into the reactor, for FCC - type reactors, the effective or instantaneous WHSV can be defined based on the amount of catalyst in contact with the feed at any given time. To achieve a desired conversion (in one non - limiting embodiment, 45% conversion) under favorable reactor temperature and pressure conditions, the WHSV should be much lower, generally in the range of 5 - 15 hours -1 , while maintaining a gas contact time range of 2 - 3 seconds in the primary reaction zone. These conditions are not easily accommodated in FCC - type reactors with a conventional riser design.

[0008] A fluidized bed reactor has the ability to handle large amounts of fluid. Fluidization occurs when small solid catalyst particles are suspended in an upward flowing fluid (gas) stream. The fluid velocity is sufficient to suspend the particles but not large enough to carry them out of the vessel. The solid particles rotate rapidly around the bed, resulting in excellent mixing with the fluid. The characteristics and behavior of the fluidized bed strongly depend on both the solid properties and the liquid or gas properties.

[0009] Commercial reactor technology typically uses a fixed bed recycle reactor system where multiple reactor beds alternate between reaction and regeneration operations, or a moving bed continuous catalyst regeneration system with intermediate heating. In these systems, the operation is semi-batch, with multiple reactors and associated valves required to simulate continuous operation.

[0010] Accordingly, it is desirable to maintain true continuous operation while employing a single reactor / regenerator system that is readily provided by an FCC-type reactor / regenerator configuration.

[0011] Overview

[0012] In one non-limiting embodiment, a reactor system for the catalytic dehydrogenation of saturated Cx hydrocarbons is provided, where the reactor system includes a reactor settler, a reactor within the reactor settler, where the reactor includes a reactor zone, a catalyst riser that is in fluid communication with the reactor at the upper end of the catalyst riser and in fluid communication with a regenerated catalyst stripper and a steam source at the lower end of the catalyst riser, an outlet riser that is in fluid communication with the upper end of the reactor, the outlet riser being in fluid communication with at least one cyclone separator adapted to separate catalyst from the reactor effluent, where the reactor includes a lower portion thereof that is open and not rigidly coupled to at least one cyclone separator,

[0013] Furthermore, a method for the catalytic dehydrogenation of saturated Cx hydrocarbons is provided, which includes feeding a saturated Cx hydrocarbon and a dehydrogenation catalyst into a reactor within a reactor settler, where the reactor includes a reactor zone that includes a lower portion thereof, dehydrogenating the saturated Cx hydrocarbon in the presence of the dehydrogenation catalyst to obtain a reactor effluent that is fed through an outlet riser to at least one cyclone separator, separating the dehydrogenated product from the spent catalyst in at least one cyclone separator, flowing the spent catalyst downward along an annular space between the reactor and the reactor settler to a spent catalyst stripper located below the reactor, where the lower portion of the reactor is open to the settler and in fluid communication with the spent catalyst flowing downward along the annular space from at least one cyclone separator, and the method further includes controlling the amount of catalyst within the reactor by varying the catalyst level in the annular space between the reactor and the reactor settler. Brief Description of the Drawings

[0015] Figure 1 is a non-limiting schematic view of a conventional reactor system for the catalytic dehydrogenation of saturated Cx hydrocarbons;

[0016] Figure 2 is a non-limiting schematic view of one version of a reactor system for the catalytic dehydrogenation of saturated Cx hydrocarbons described and illustrated herein;

[0017] Figure 3 is a different, non-limiting schematic view of another embodiment of a reactor system for the catalytic dehydrogenation of saturated Cx hydrocarbons described and illustrated herein

[0018] Figure 4 is another non-limiting schematic view schematically showing different embodiments of reactor systems in a side-by-side configuration.

[0019] It will be understood that the drawings are schematic illustrations and the present invention is not limited to the designs, ratios or specific equipment shown in the drawings.

[0020] Detailed description

[0021] The object of the present invention is to provide a reactor for Cx dehydrogenation, wherein the WHSV can be operated in the range of 5 - 15 hours -1 while being able to obtain most (if not all) of the benefits of conventional FCC-type conversion systems such as KBR FCC ORTHOFLOW TM design, to give a non-limiting example. Figure 1 shows a schematic view of such a conventional reactor system. The present invention solves the following:

[0022] · How to achieve a low WHSV in the range of 5 - 15 hours with a gas contact time of 2 - 3 seconds in an FCC-type dilute-phase fluidized reactor -1 range.

[0023] · How to provide a method for adjusting the reaction WHSV without affecting the overall reactor heat balance.

[0024] Another important parameter in reactor design is the gas residence time, wherein in one non-limiting embodiment, the goal is in the range of 1 - 2 seconds in the reactor zone. The gas residence time is the reciprocal of the gas space velocity (GHSV), and for the external riser reactor 116, it is defined based on the volume of the riser (see Figure 1). The gas residence time is also a function of the gas void fraction, expressed as (reactor volume × gas void fraction) / volume flow rate.

[0025] Part of the concept of the systems and methods described herein is to increase the relatively large-diameter reactor section, which achieves a fluidized catalyst bed density much higher than that achieved by a conventional riser by reducing the gas velocity moving upward through the reaction zone, i.e., by transitioning from a dilute phase to a fast fluidization state. This design provides the desired WHSV and gas residence time. In one non-limiting embodiment, the desired WHSV can be in the range of about 5 to about 15 hours -1 ; alternatively, the WHSV is about 10 - 15 hours -1 . In another non-limiting version, the desired gas residence time can be in the range of about 0.5 to about 3 seconds; alternatively, about 1 to about 2 seconds; and in another non-limiting embodiment, less than 1 second within the reactor.

[0026] As defined herein, a "relatively large-diameter reactor" means that the reactor has a length and a diameter, and the ratio of length to diameter L / D independently ranges from about 1:1 to about 5:1; alternatively, independently ranges from about 2:1 to about 3:1. That is, the reactor is of the general shape of a vessel, rather than the general shape of a riser or a pipe. As used herein with respect to ranges, the word "independently" means that any endpoint can be used with any other endpoint to give a suitable alternative range.

[0027] It should be understood that although these challenges of FCC-type reactors are addressed in the designs for dehydrogenation reactions discussed herein, these designs and methods are not limited to dehydrogenation reactions and are expected to be applicable to other reactions.

[0028] It is recognized that other reactor designs include the possible concept of a large-diameter reaction section at the top or bottom of a riser. However, this design and method differ from other designs and methods in the following features.

[0029] Stacked reactor-regenerator configuration

[0030] Referring Figure 2 , which illustrates a non-limiting schematic version of a reactor system 210 for the catalytic dehydrogenation of saturated C3 - C6 hydrocarbons:

[0031] a) As Figure 2 shown, the reactor section 212 is located inside the reactor settler 214 (stacked reactor - regenerator configuration), as opposed to the top or bottom of an external riser.

[0032] b) The external riser 216 is not used for reaction but only for transporting the catalyst from the regenerator 218 to the reaction zone 220, which eliminates the additional feed gas residence time in the riser. This is in contrast to the prior configuration shown in FIG. 1 where the external riser reactor 116 is used as a reactor. The steam introduced at 236 serves as the catalyst lift medium and also serves the additional purpose of reducing the hydrocarbon partial pressure to improve reaction selectivity.

[0033] c) The catalyst and reaction products leave the reactor 212 through the outlet riser 222, which operates in a general riser dilution flow regime. The outlet riser 222 feeds a series of primary cyclones 224P in series, followed by secondary cyclones 224S, to separate the catalyst from the reactor effluent.

[0034] d) A quench gas is introduced through a quench gas feed (not shown) after the first set of cyclones 224P to reduce the gas temperature by about 25 °C (in one non-limiting embodiment) and to inhibit further cracking reactions. The quench gas is introduced before the second set of cyclones 224.

[0035] e) The catalyst separated in the cyclones 224 flows downward along the settler 214 through the annular region 226 between the reactor 212 and the settler 214 to reach the spent catalyst stripper 228.

[0036] f) The reactor section 212 is open at the bottom 230, which provides the advantage that the amount of catalyst within the reactor section 212 can be controlled by varying the catalyst level in the annular section 226 of the settler 214 external to the reactor 212. This design makes it possible to control the total catalyst holdup / WHSV independently of the regenerated catalyst flow from the regenerator 218; thus, the WHSV in the reactor 212 can be varied without affecting the heat balance. The regenerated catalyst flows from the regenerator 218 to the regenerated catalyst stripper 238, and the stripped regenerated catalyst flows through the slide valve 240 and is introduced into the inlet 242 to be lifted by the steam 236 introduced through the crossover tube 244 into the reactor 212. The regenerator 218 also includes an upper regenerator 219, a lower regenerator 221, and a regenerator cyclone 250. The flue gas from the regenerator cyclone 250 leaves through the flue gas plenum 252.

[0037] g) Notably, the outlet riser 222 is not rigidly coupled to the cyclone separator 224 (gap 256), which allows for pressure equalization with the dilution space in the reactor settler 226, facilitating the level changes discussed in f) above. More specifically, the cyclone separator 224 is rigidly coupled to the top of the outlet riser 222 (negative pressure sealed cyclone separator system). There is a gap 256 in the riser 222 before the first cyclone separator 224P to allow the dip tube gas and vapor to leave the reactor 212 through the cyclone separator system. The exact location of the gap 256 is not important; for example, it can be between the cyclone separators 224P and 224S. The level changes in the annular region 226 are independently controlled by opening and closing the spent catalyst slide valve 240 to vary the level.

[0038] h) The Cx feed 232 to the reactor 212 is introduced into the bottom 230 of the reactor 212 through a distributor 234. In one non - limiting embodiment, the distributor 234 has the appearance of a mushroom - shaped top or any other suitable shape to distribute the saturated hydrocarbon feed into the reactor 212.

[0039] i) In another non - limiting embodiment, a KBR's sealed cyclone separator system is used to minimize the gas residence time.

[0040] j) In another non - limiting version, KBR's proven unique regenerator heating system (KCOT TM ) can also be employed.

[0041] Alternative reactor-regenerator configuration

[0042] Figure 3 Shows a non - limiting, alternative schematic version of a reactor system 310 for the catalytic dehydrogenation of saturated Cx hydrocarbons.

[0043] a) The reactor section 312 is located inside the reactor settler 314, which has a different stacked reactor - regenerator configuration, as Figure 3 shown, as opposed to the top or bottom of an external riser.

[0044] b) Similarly, the external riser 316 is not used for reaction but only for transporting catalyst from the regenerator 318 to the reaction zone 320, which eliminates additional feed gas residence time in the riser. This is in contrast to the existing configuration shown in FIG. 1 where an external riser reactor 116 is used as a reactor. The steam introduced at 336 serves as the catalyst lift medium and also serves the additional purpose of reducing the hydrocarbon partial pressure to improve reaction selectivity.

[0045] c) The catalyst and reaction products leave the reactor 312 via the outlet riser 322, which operates in a generally riser dilution flow regime. The outlet riser 322 feeds a series of cyclones 324 (primary cyclones 324P and secondary cyclones 324S) to separate the catalyst from the reactor effluent.

[0046] d) A quench gas is introduced via a quench gas feed (not shown) after the first set of cyclones 324P to reduce the gas temperature by about 25 °C (in one non-limiting embodiment) and to inhibit further cracking reactions. The quench gas is introduced prior to the second set of secondary cyclones 324S.

[0047] e) The catalyst separated in the cyclones 324P and 324S flows downward along the settler 314 through the annular region 326 between the reactor 312 and the settler 314 to reach the spent catalyst stripper 328.

[0048] f) The reactor section 312 is open at its bottom 330, which provides the advantage that the amount of catalyst within the reactor section 312 can be controlled by varying the catalyst level in the annular section 326 of the settler 314 external to the reactor 312. This design again makes it possible to control the total catalyst holdup / WHSV independently of the catalyst flow from the regenerator 318; thus, the WHSV in the reactor 312 can be varied without affecting the heat balance. The regenerated catalyst flows from the regenerator 318 to the regenerated catalyst stripper 338, and the stripped regenerated catalyst flows through the slide valve 340 and is introduced into the riser 316 to be lifted by the steam 336 introduced through the crossover pipe 344 into the reactor 312. The regenerator 318 also includes an upper regenerator 319, a lower regenerator 321, and regenerator cyclones 350. The flue gas from the regenerator cyclones 350 leaves via the flue gas plenum 352.

[0049] g) Notably, the outlet riser 322 is not rigidly coupled to the cyclones 324 (there is a gap 356), which allows for pressure equalization with the dilution space pressure in the reactor settler 326, facilitating the level changes discussed in f) above. The details of the stacked reactor - regenerator configuration given above for Figure 2 the alternative configuration in g) are equally applicable.

[0050] h) In a non-limiting embodiment, the Cx feed 332 to the reactor 312, such as a propane feed, is introduced into the bottom 330 of the reactor 312 via an annular distributor. Other suitable distributor types include but are not necessarily limited to grid-type, mushroom-type, or any suitable design that provides thorough distribution.

[0051] i) The regenerated catalyst and lift steam enter the bottom 330 of the reactor 312 via the crossover pipe 344 through the opening 348 as an alternative to being introduced directly into the reactor 312 from the crossover pipe 344. In one non-limiting embodiment, the opening slot 348 distributes the regenerated catalyst and lift steam into the reactor 312. The shape and number of the opening 348 are not important as long as good distribution of the regenerated catalyst and lift steam into the reaction zone 320 is achieved.

[0052] Figure 3 The other details of the alternative system 310 in Figure 2 are similar to those of the system 210 in

[0053] Side-by-side reactor-regenerator configuration

[0054] A second configuration is also envisioned, more precisely a side-by-side reactor-regenerator configuration, and is shown in Figure 4 This configuration is very similar to the configuration shown in Figure 3 except that the settler 414 including the reactor 412 is laterally displaced from its position shown in Figure 3 as shown in Figure 4 In a non-limiting embodiment of Figure 4 it is positioned above the riser 416 (to the left and optionally downwards relative to the embodiment of Figure 3 ). In an optional embodiment, the settler 414 and the reactor 412 can be coaxial with the riser 416. Thus, the reactor 412 and the regenerator 418 are in a side-by-side relationship rather than a stacked relationship. More specifically:

[0055] a) The riser 416 (external or internal) is used to transport the catalyst from the regenerator 418 into the reactor 412.

[0056] b) For the external riser 416, refer to the description of subparagraphs a) to j) under "Stacked Reactor-Regenerator Configuration" discussed above.

[0057] c) For the internal riser 416, a portion of the riser 416 can also be used for the reaction. When used to effect the reaction, the Cx feed is introduced into the riser 416 such that the cross-sectional area or length of the riser reaction zone is minimized.

[0058] d) The steam 436 serves as the main catalyst lift medium in the riser 416 and is also used for the additional purpose of reducing the hydrocarbon partial pressure to improve reaction selectivity.

[0059] e) The catalyst and reaction products leave the reactor 412 via the outlet riser 422, which operates in a generally riser dilution flow regime. The outlet riser 422 feeds the series of cyclones 424P and 424S to separate the catalyst from the reactor effluent.

[0060] f) Quench gas is introduced via a quench feed (not shown) after the primary cyclone 424P to reduce the gas temperature by about 25 °C and inhibit further cracking reactions. The quench gas is introduced upstream of the secondary cyclone 424S.

[0061] g) The catalyst separated in the cyclones 424 flows downward along the settler 414 through the annular region 426 between the reactor 412 and the settler 414 to reach the spent catalyst stripper 428.

[0062] h) As discussed above, the reactor section 412 is open at the bottom 430, which provides the advantage that the amount of catalyst within the reactor 412 can be controlled by varying the catalyst level in the annular section 426 of the settler 414 external to the reactor 412. This design enables the total catalyst holdup / WHSV to be controlled independently of the catalyst flow from the regenerator 418; thus, the WHSV in the reactor 412 can be varied without affecting the heat balance.

[0063] i) Again, the outlet riser 422 is not rigidly coupled to the cyclone 424 (there is a gap 456), which allows pressure equilibration with the dilution space in the reactor settler 426, facilitating the level changes discussed in f). Similarly, the details given above regarding Figure 2 the stacked reactor - regenerator configuration in g) and Figure 3 the alternative reactor - regenerator configuration in g) are equally applicable to this side - by - side configuration.

[0064] j) Additional Cx feed 432 to the reactor 412 can also be introduced via a distributor at the bottom of the reactor 412 as described previously.

[0065] Other details of the side - by - side system are similar to those of the stacked reactor - regenerator system and the alternative reactor - regenerator system described previously. For example, Figure 4 the slide valve 454 in Figure 3 corresponds to the plug valve 354 in

[0066] In the design of this system ( Figure 2 、 3As shown in FIGS. 2 and 4, the catalyst in the reactors (212, 312, 412) is a combination of regenerated catalyst entering from the risers (216, 316, 416) and spent catalyst entering the bottom of the reactors (212, 312, 412) from the disengagers (214, 314, 414). The reactor effluent and the catalyst leave the reactors (212, 312, 412) through the outlet risers (222, 322, 422), which operate under normal riser flow conditions.

[0067] Four main components enter the internal reactor: fresh regenerated catalyst; spent catalyst; steam; and Cx feed. This section describes some additional features and potential arrangements for introducing these components.

[0068] Regenerated catalyst

[0069] In one non-limiting embodiment, the regenerated catalyst is transferred with lift steam (236, 336) from the vertical external risers (216, 316) to the side of the internal reactor (212, 312) through cross-pipe conduits (244, 344). The catalyst is introduced above the Cx feed distributor (234) (see Figure 2 ). This can be achieved using one or more risers.

[0070] The regenerated catalyst is transferred with lift steam (236, 336) from the vertical external risers (216, 316) through horizontal cross-pipe conduits (244, 344) and additional internal vertical risers to the center of the bottom of the internal reactor. The catalyst is introduced at approximately the same location as the Cx feed distributor (234). The catalyst is distributed across the cross-section of the reactors (212, 312) through a catalyst distributor (openings 348 in the vertical risers or other suitable catalyst distribution devices; see Figure 3 ).

[0071] In one non-limiting embodiment, in a side-by-side reactor-regenerator configuration with an internal riser, the regenerated catalyst and lift steam (436) and optionally Cx are transferred from the vertical internal riser to the center of the internal reactor (412). In another non-limiting embodiment, the catalyst is introduced above or at the same level as an additional Cx feed distributor 432 (if present) (see Figure 4 ). This can be achieved using one or more risers 416.

[0072] Cx feed

[0073] Cx can be introduced through a distributor 234 at the bottom of the internal reactor 212 (see Figure 2 ).

[0074] The Cx distributor 234 can be of the mushroom / dome type, grid type, annular type, riser nozzle, or any other type of distributor suitable for introducing Cx into the internal reactor or riser.

[0075] The Cx distributor 234 is designed to enable good coverage of the entire cross-sectional area of the reactor (212, 312, 412); and to ensure close contact between the catalyst and the Cx feed.

[0076] Cx can also be introduced into the horizontal crossover pipes (244, 344) or into the riser to promote better mixing before entering the reactor (212, 312) - this can be implemented in bottom-entry or side-entry arrangements.

[0077] In the reactor designs described herein, Cx together with steam (236, 336, 436) enables the realization of a fast-fluidized catalyst bed reactor system where the desired WHSV is achieved.

[0078] Spent catalyst

[0079] After the spent catalyst is separated from the product gas in the cyclone separators (224, 324, 424), it is introduced through the cyclone dip tubes and enters the annular space (226, 326, 426) between the internal reactor (212, 312, 412) and the settler (214, 314, 414) walls.

[0080] The spent catalyst enters the internal reactor (212, 312, 412) through the open bottom (230, 330) and is mixed with the Cx feed (232, 332, 432) and fresh regenerated catalyst. The sequence of first mixing the Cx feed with the low-temperature spent catalyst and then with the fresh catalyst has potential yield advantages. Also, the catalyst bed below and around the reactor (212, 312, 412) is a relatively dense phase.

[0081] A dense catalyst bed is maintained in the annular space (226, 326) between the reactor (212, 312) below and the internal reactor (212, 312) and the settler (214, 314) walls.

[0082] The un-recycled spent catalyst flows into the stripper vessels (238, 338, 438) below the internal reactor (212, 312, 412), and then into the regenerator (218, 318, 418), where the spent catalyst is regenerated and returned to the internal reactor (212, 312, 412).

[0083] Catalyst bed adjustment

[0084] The catalyst holdup (or WHSV) in the reactor vessels (212, 312, 412) can be changed by varying the amount of recycled spent catalyst that returns from the cyclone dip tubes and enters the reactor (212, 312, 412) through the bottom of the openings in the reactor (212, 312, 412).

[0085] The design includes the flexibility to vary the height of the catalyst in the annular spaces (226, 326, 426) external to the reactors (212, 312, 412). This makes it possible to control the amount of spent catalyst recycled back into the reactors (212, 312, 412). The concept is based on catalyst bed hydraulics. A higher annular bed level results in an increased head, which pushes more spent catalyst into the reactors (212, 312, 412). Conversely, a lower annular bed level results in a lower head, which reduces the amount of spent catalyst entering the reactors (212, 312, 412).

[0086] The reactor bed density is generally lower than the bed density in the annular spaces surrounding the reactors (212, 312, 412) and the bed density below the reactors (212, 312, 412), but controlling the annular bed height via the spent catalyst plug valves / slide valves (254, 354, 454) allows for the regulation of spent catalyst recycle regardless of the bed density in the annular sections (226, 326, 426). The difference in bed density will affect the final height of the catalyst bed in the annular spaces (226, 326, 426), but as long as there is flexibility to change the bed height in the annular spaces (226, 326, 426), what the annular bed density is doesn't really matter. In one non - limiting embodiment, the annular bed density is desirably about 30 - 40 pounds per foot 3 , but the concepts, designs, and methods described herein can operate outside of this range.

[0087] The annular bed catalyst level is controlled by adjusting Figure 2 and 3 the spent catalyst plug valves (254, 354) in a stacked design or the slide valve (454) in a side - by - side design, such as Figure 4 shown. Closing the valves (254, 354, 454) increases the catalyst inventory / annular bed height. Opening the valves (254, 354, 454) decreases the catalyst inventory / annular bed height. This is similar to how the reactor / stripper bed level is maintained in a typical FCC, but now it operates over a wider level range.

[0088] The cyclone separator system is rigidly coupled to the top of the outlet risers (222, 322, 422). The bottoms of the outlet risers (222, 322, 422) are connected to the reactors (212, 312, 412). Prior to the first-stage cyclones (224P, 324P, 424P), there are gaps (256, 356, 456) in the outlet risers (222, 322, 422) to allow the dip-tube gas and steam to leave the disengager (214, 314, 414) dilute phase through the respective cyclone separator systems; and to allow pressure equalization between the disengager (214, 314, 414) dilute phase and the cyclone separator system. The pressure at the inlet of the first-stage cyclones (224P, 324P, 424P) is equal to the disengager (214, 314, 414) dilute-phase pressure. As previously mentioned, this pressure equalization gap (256, 356, 456) can be located prior to the primary cyclones (224P, 324P, 424P); between the primary cyclones (224P, 324P, 424P) and the secondary cyclones (224S, 324S, 424S); or after the secondary cyclones (224S, 324S, 424S). In one non-limiting embodiment, Figure 2 , 3 and the location prior to the primary cyclones (224P, 324P, 424P) illustrated in 4 is suitable.

[0089] The catalyst bed level in the annular sections (226, 326, 426) does not affect the pressure equalization of the cyclones. In any case, the pressure equalization feature enables the normal operation of the entire system. In the absence of the pressure equalization feature, the disengager dilute-phase pressure would keep increasing because the steam and dip-tube gas would have nowhere to escape. The cyclone separator system would not operate properly. Additionally, it would become increasingly difficult to control the annular bed level and the spent catalyst recycle.

[0090] The amount of catalyst in a typical FCC riser is changed by increasing the catalyst circulation (by various means such as raising the reactor temperature, lowering the feed temperature, etc.). These adjustments also change the heat balance.

[0091] However, in contrast, in the present system, the amount of catalyst in the reactor can be changed by varying the amount of spent catalyst recycle without affecting the heat balance - the amount of recycled catalyst does not change. The WHSV regulation is independent of the catalyst circulation / regenerated catalyst flow.

[0092] Steam

[0093] Steam (236, 336, 436) is used to lift the regenerated catalyst to the external or internal risers (216, 316, 416) and into the reactors (212, 312, 412).

[0094] It will be understood that other gases (such as N 2 ) and / or vapors can also be used as catalyst promotion media.

[0095] A non-limiting advantage of the systems and methods described herein is that the low WHSV required for the Cx dehydrogenation reaction can be accommodated in an FCC-type reactor. Conventional fixed-bed reaction systems suffer from recycle operations and associated maintenance issues, whereas using an FCC-type reaction avoids recycle operations and has continuous catalyst replenishment.

[0096] In the foregoing specification, the invention has been described with reference to its specific embodiments. However, the specification should be regarded as illustrative rather than limiting in sense. For example, equipment, risers, reactors, settlers, towers, regenerators, valves, clearances, methods, reactants, saturated hydrocarbons, products, and operating conditions that fall within the claimed or disclosed parameters but are not specifically determined or tried in the specific embodiments are expected to be within the scope of the invention.

[0097] The invention can be practiced in the absence of an undisclosed element. Additionally, the invention can suitably include, consist of, or consist essentially of the disclosed elements. For example, a reactor system for the catalytic dehydrogenation of saturated Cx hydrocarbons can be provided, where the reactor system includes, consists essentially of, or consists of the following: a reactor settler; a reactor within the reactor settler, where the reactor includes a reactor zone; a catalyst riser that is in fluid communication with the reactor at the upper end of the catalyst riser and is in fluid communication with a regenerated catalyst stripper and a steam source at the lower end of the catalyst riser; and an outlet riser that is in fluid communication with the upper end of the reactor and is in fluid communication with at least one cyclone separator adapted to separate catalyst from the reactor effluent; where the reactor includes its lower portion that opens into the reactor settler.

[0098] A method for the catalytic dehydrogenation of saturated Cx hydrocarbons can also be provided, the method including, consisting essentially of, or consisting of the following: feeding a saturated Cx hydrocarbon and a dehydrogenation catalyst into a reactor within a reactor settler, where the reactor includes a reactor zone that includes its lower portion; dehydrogenating the saturated Cx hydrocarbon in the presence of the dehydrogenation catalyst to obtain a reactor effluent that is fed through an outlet riser to at least one cyclone separator; separating the dehydrogenation product from the spent catalyst in at least one cyclone separator; flowing the spent catalyst downward along an annular space between the settler and the reactor to a spent catalyst stripper and then to a catalyst regenerator; where the lower portion of the reactor opens into the settler and is in fluid communication with the annular space, and the method further includes controlling the amount of catalyst in the reactor by varying the catalyst level in the annular space.

[0099] As used throughout the claims, the terms "comprising" and "comprises" shall be interpreted as "including but not limited to" and "including but not limited to", respectively.

[0100] As used herein, the term "substantially" shall mean "mostly but not all of the specified".

[0101] As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are also intended to include the plural forms.

[0102] As used herein, the term "about" with respect to a given parameter includes the recited value and has the meaning determined by the context (e.g., it includes the degree of error associated with the measurement of the given parameter).

[0103] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

Claims

1. A reactor system for the catalytic dehydrogenation of saturated Cx hydrocarbons, wherein the reactor system comprises: a reactor settler; a reactor within the reactor settler, wherein the reactor comprises a reactor zone; a catalyst riser fluidly connected to the reactor at its upper end and fluidly connected to a regenerated catalyst stripper and a steam source at its lower end; and an outlet riser fluidly connected to the upper end of the reactor, the outlet riser being fluidly connected to at least one cyclone separator adapted to separate catalyst from the reactor effluent; wherein the reactor comprises its lower part that opens into the reactor settler.

2. The reactor system according to claim 1, wherein the reactor has a length and a diameter, and the ratio of the length to the diameter ranges from about 1:1 to about 5:

1.

3. The reactor system according to claim 1, wherein the outlet riser is open to at least one cyclone separator.

4. The reactor system according to claim 1, wherein the settler has its lower part fluidly connected to a catalyst regenerator.

5. The reactor system according to claim 1, further comprising a quench gas feed located downstream of the at least one primary cyclone separator and upstream of the secondary cyclone separator.

6. The reactor system according to claim 1, further comprising a saturated Cx hydrocarbon feed fluidly connected to the lower part of the reactor.

7. The reactor system according to claim 6, wherein the reactor has an open bottom, and the saturated Cx hydrocarbon feed fluidly connected to the lower part of the reactor feeds a distributor at the bottom of the reactor.

8. The reactor system according to claim 1, wherein the reactor and the reactor settler are located above a catalyst regenerator, and the catalyst riser is outside the settler and the catalyst regenerator.

9. The reactor system according to claim 1, wherein the reactor and the reactor settler are located at the side of a catalyst regenerator, and the catalyst riser is outside or inside the settler and the catalyst regenerator.

10. The reactor system according to claim 9, wherein in the case where the catalyst riser is inside the settler, at least a part of the catalyst riser is the reactor.

11. A reactor system for the catalytic dehydrogenation of saturated C3-C6 hydrocarbons, wherein the reactor system comprises: a reactor settler; a reactor within the reactor settler, wherein the reactor comprises a reactor zone; a catalyst riser fluidly connected to the reactor at its upper end and fluidly connected to a regenerated catalyst stripper and a steam source at its lower end; and an outlet riser fluidly connected to the upper end of the reactor, the outlet riser being fluidly connected to at least one cyclone separator adapted to separate catalyst from the reactor effluent; wherein: the reactor comprises its lower part, which is open to the reactor settler and not rigidly coupled to at least one cyclone separator; the reactor has a length and a diameter, and the ratio of the length to the diameter ranges from about 1:1 to about 5:

1.

12. A method for the catalytic dehydrogenation of saturated Cx hydrocarbons, which comprises: Feed a saturated Cx hydrocarbon and a dehydrogenation catalyst to a reactor within a reactor settler, wherein the reactor includes a reactor zone including its lower part; Dehydrogenate the saturated Cx hydrocarbon in the presence of the dehydrogenation catalyst to obtain a reactor effluent fed through an outlet riser to at least one cyclone separator; Separate the dehydrogenation product from the spent catalyst in at least one cyclone separator; Cause the spent catalyst to flow downward along an annular space between the settler and the reactor to a spent catalyst stripper and a catalyst regenerator; Wherein the lower part of the reactor is open to the settler and is in fluid communication with the annular space, and the method further includes controlling the amount of catalyst in the reactor by changing the catalyst level in the annular space.

13. The method for catalytic dehydrogenation according to claim 12, wherein the reactor has a length and a diameter, and the ratio of the length to the diameter ranges from about 1:1 to about 5:

1.

14. The method for catalytic dehydrogenation according to claim 12, wherein the total catalyst holdup and / or the weight hourly space velocity (WHSV) is controlled independently of the catalyst flow rate from the catalyst regenerator.

15. The method for catalytic dehydrogenation according to claim 12, wherein the outlet riser is open and the pressure between the reactor and the reactor settler is balanced.

16. The method for catalytic dehydrogenation according to claim 12, wherein the quench gas is introduced downstream of at least one primary cyclone separator and upstream of a secondary cyclone separator.

17. The method for catalytic dehydrogenation according to claim 12, wherein the reactor has an open bottom, and wherein the saturated Cx hydrocarbon is fed to the reactor through a distributor at the bottom of the reactor.

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