Optimized reactor center tube

Abstract

A process is described that increases the aromatics yield, or hydrogen yield, or reformate octane, or a combination thereof, under a selected set of operating conditions in a reforming process. The process uses a center tube with a top connection section, a bottom connection section, and a middle connection section, where the diameter of the middle section is smaller than the diameter of the top connection section, or the bottom connection section, or both. This arrangement can exist in one or more of the reforming reactors in the reforming reaction zone. A method is also described to optimize the diameter of the middle section.

Description

Related applications

[0001] This application claims priority to U.S. Nonprovisional Patent Application Serial No. 19 / 041,269, filed January 30, 2025, which claims priority to U.S. Provisional Patent Application Serial No. 63 / 568,931, filed March 22, 2024, the entire contents of which are incorporated herein by reference. Background Technology

[0002] In a common form, the reforming process can employ catalyst particles in several interconnected reaction zones arranged in a series flow configuration. Any number of reactors can exist within the reforming reaction zones, but typically there are three, four, or five zones. Because reforming reactions typically occur at high temperatures and are generally endothermic, each reaction zone usually has one or more associated heating zones that heat the reactants to the desired reaction temperature.

[0003] Catalyst particles typically consist of one or more Group VIII (IUPAC 8-10) noble metals (e.g., platinum, iridium, rhodium, and palladium) and a halogen combined with a porous support (such as a refractory inorganic oxide). For example, U.S. Patent No. 2,479,110 teaches an alumina-platinum-halogen reforming catalyst. Although the catalyst may contain about 0.05 wt% to about 2.0 wt% of a Group VIII metal, less expensive catalysts, such as those containing about 0.05 wt% to about 0.5 wt% of a Group VIII metal, may be used. Additionally, the catalyst may contain indium and / or lanthanides, such as cerium. The catalyst particles may also contain one or more Group IVA (IUPAC 14) metals (e.g., tin, germanium, and lead), such as those described in U.S. Patent Nos. 4,929,333, 5,128,300, and the references cited therein. The halogen is typically chlorine, and alumina is typically the support. Suitable alumina materials include, but are not limited to, γ-alumina, η-alumina, and θ-alumina. One property related to catalyst performance is the surface area of ​​the support. Preferably, the surface area of ​​the support is from about 100 m² / g to about 500 m² / g. Catalysts with a surface area less than about 130 m² / g tend to be more adversely affected by catalyst coke than catalysts with a higher surface area. Generally, the particles are typically spherical and have a diameter from about 1.6 mm to about 3.1 mm (about 1 / 16 inch to about 1 / 8 inch), although they can be as large as about 6.35 mm (about 1 / 4 inch) or as small as about 1.06 mm (about 1 / 24 inch). However, in certain reforming reaction zones, it is desirable to use catalyst particles falling within a relatively narrow size range.

[0004] Typical feed inlet temperatures for reformers are 440°C to 580°C (824°F to 1076°F), or 500°C to 580°C (932°F to 1076°F), or 540°C to 580°C (1004°F to 1076°F), or at least above 540°C (932°F). Reformers can operate at different temperatures; for example, a first reformer may operate at 500°C to 540°C (932°F to 1004°F), and a subsequent second reformer may operate at a temperature greater than 540°C (1004°F). Reformers can operate at a range of pressures typically ranging from about 0 kPa(g) to about 6,895 kPa(g) (about 0 psi(g) to about 1,000 psi(g)), or from about 276 kPa(g) to about 1,379 kPa(g) (about 40 psi(g) to about 200 psi(g)). To achieve higher aromatic yields, lower operating pressures are particularly preferred. Reaction conditions also include a liquid hourly space velocity (LHSV) in the range of 0.6 hr⁻¹ to 10 hr⁻¹. Preferably, the LHSV is 0.6 hr⁻¹ to 5 hr⁻¹, more preferably 1 hr⁻¹ to 5 hr⁻¹, and most preferably 2 hr⁻¹ to 5 hr⁻¹. The catalyst residence time in the reformer is also 0.5 h to 36 h.

[0005] The goal is to find a low-cost solution to improve process efficiency, such as improved aromatic yield, hydrogen yield, higher reformate octane and / or higher unit throughput, without increasing the size of the reformer. Attached Figure Description

[0006] Figure 1 This is an example of one embodiment of a reforming reactor according to the present invention.

[0007] Figure 2 This is an example of one embodiment of the bottom portion of the reforming reactor according to the present invention.

[0008] Figure 3 This is an example of one embodiment of the top portion of the reforming reactor according to the present invention.

[0009] Figure 4 This is a flowchart of an iterative calculation method for optimizing aromatic yield based on changes in catalyst volume and reactor pressure increments according to the present invention.

[0010] Figure 5 This is a graph showing the sensitivity of the change in aromatic yield increment as a function of reactor volume increment.

[0011] Figure 6 This is a graph showing the sensitivity of the change in aromatic yield increment as a function of the pressure drop in reactor 4.

[0012] Figure 7 This is a graph showing the reactor pressure drop as a function of the reactor volume increment. Detailed Implementation

[0013] The optimized central tube of the present invention increases the volume of the catalyst bed in new or existing reactors by optimizing the central tube geometry.

[0014] This method can be used to optimize the center tube of existing reforming units, allowing for a 3% to 25% increase in catalyst volume without replacing the reactor shell or subjecting catalyst pinning constraints. Increased unit operating margins resulting from higher aromatic yields or higher reformate RONC (research octane number, clarified) products, higher hydrogen yields, and / or higher unit throughput provide an economic justification for retrofitting existing stacked reactor center tubes in refineries.

[0015] Modified units with optimized reactor center tubes can significantly increase the amount of catalyst in existing reactors.

[0016] The optimized center tube can be used in conjunction with an improved catalyst to further enhance the aromatics and / or hydrogen yield and / or throughput of the unit.

[0017] Specifically, for stacked or side-by-side reactor arrangements, the central tubes in reactors 2, 3, and 4 typically have a significant amount of catalyst pinning margin compared to reactor 1. In radial flow reactors with moving bed catalysts, reactants flow from the fan-shaped section towards the central tube. When the flow velocity through a given cross-sectional area of ​​the central tube is too high, the radial flow presses the catalyst pellets against the central tube wall, increasing friction and preventing catalyst movement. As the central tube diameter decreases, the gas velocity increases for a given cross-sectional area. To avoid catalyst pinning, the central tube diameter must be large enough. However, if the central tube diameter is larger than required, reactor utilization is low, resulting in waste.

[0018] The central tube includes a top connecting section, a bottom connecting section, and a middle section.

[0019] The diameter of the perforated section or screen (middle section) of the reactor's central tube can be reduced for optimization while maintaining the original central tube outlet diameter and the geometry of the existing central tube support plate. In other words, the diameter of the profile screen section is smaller than the rest of the central tube. By keeping the top and bottom of the central tube geometry the same as the original dimensions, refineries can replace their existing central tubes with this concept without modifying the rest of the reactor. Therefore, the impact on turnaround time or production losses is minimal or nonexistent compared to replacing it with a larger, stacked reactor shell with the same construction as the existing central tube.

[0020] Typically, the top flange region and bottom plate of the central tube are not modified. The transition from the top flange region to the intermediate section of the central tube forms an angle of approximately 5° to 45° with vertical. The transition cone can be made of a blind plate or slotted plate that prevents catalyst stagnation and allows gas passage. The transition cone enhances catalyst and gas flow distribution. The intermediate section has a smaller diameter than the top flange plate, bottom plate, or both. The intermediate section has openings or perforations.

[0021] In some implementations, the intermediate section will be reduced only relative to the top connection, or only relative to the bottom connection, or relative to both the top and bottom connections.

[0022] The diameter reduction in the intermediate section can be accomplished in one or more reformers within the reforming reactor. The reduction can be the same in all reactors, or it can be different in one or more reactors.

[0023] Several factors need to be considered when providing a transition between the middle section of the central tube and the bottom connection with a larger diameter. The design should minimize stagnant catalyst buildup and tail catalyst formation (due to the stagnant nature of the catalyst, the coke content is greater than 10%), and provide good airflow distribution. It should maintain the mechanical integrity of the central tube. Finally, it should minimize or eliminate the need for additional field work for the implementation of the modified unit or the installation of the central tube.

[0024] One possibility for the bottom of the optimized central tube involves multiple ceramic ropes looped around the bottom of the profile wire mesh. The ceramic rope system consists of more than one ceramic ring with different rope diameters. By placing the ring with the smaller diameter rope at the top and the ring with the larger diameter rope at the bottom, they together form an inclination of 5 to 45 degrees from vertical at the base of the optimized central tube. This angle is sufficient to overcome the angle of repose of the catalyst pellets, preventing the formation of stagnant catalyst there. Alternatively, multiple bottom plates with increased outer diameters, conical rings made of slotted plates or stamped plates, conical cladding, or transition cones can be used. Alternatively, the bottom transition can be made of a truncated cone, which provides the inclination angle to avoid catalyst stagnation. This truncated cone can be made with or without perforations.

[0025] For a radial flow reactor, given a reactor shell diameter and tangential length, the catalyst bed volume is defined by the annular space between the sector and the central tube.

[0026] The diameter of the central tube in the first reactor is typically determined based on pinning constraints (which may be other constraints in some cases). Downstream reactors (e.g., reactors 2 through 4) typically have a large margin in terms of pinning constraints. For a given reactor stack, many reforming units in commercially operating reforming units have the same central tube outer diameter for all reactors. By doing so, all of these can be removed from the reactor body flange at the top of the stack for maintenance and repair during turnaround.

[0027] The reactor pressure drop includes inlet loss, sector riser loss, axial loss along the sector, sector front, catalyst bed (bed depth), central tube screen, perforated plate (artificially applied pressure drop), axial loss along the central tube, and mitered elbow and outlet loss.

[0028] For a reactor with a tapered sector (i.e., a larger cross-sectional area at the top and a smaller cross-sectional area at the bottom), it will have a higher velocity head compared to the central tube. This can result in a higher degree of vapor skewness and uneven vapor distribution compared to a non-tapered sector. To overcome this, an artificial pressure drop can be applied to the perforated central tube, but this results in a higher overall reactor pressure drop, leading to a higher reactor operating pressure.

[0029] To increase the aromatics yield and / or feed rate throughput of existing reactors, a common retrofit design involves adding a new reactor to the existing unit.

[0030] For a given catalyst bed height, a larger catalyst bed volume tends to result in a higher reactor pressure drop. A higher pressure drop leads to a higher operating reactor pressure. Under given operating conditions, a higher operating reactor pressure directionally reduces aromatics yields. This is due to… Figure 6 This confirms that the graph illustrates the relationship between the increase in aromatic yield (due to a larger catalyst volume) and the increase in reactor pressure drop. The benefit of an increase in aromatic yield from a given catalyst volume can be mitigated by an increase in reactor pressure drop (or at higher operating reactor pressures).

[0031] As is well known, a higher reactor pressure drop often reduces the uneven distribution of vapor in the catalyst bed.

[0032] Reducing the diameter of the central tube increases the catalyst bed depth between the sector and the central tube. Reducing the central tube diameter also decreases the area available for perforation, or the open area of ​​the central tube screen. Together, these factors increase the pressure drop between the sector and the screen of the central tube. To optimize catalyst-reactant contact for increased yield, it is helpful to correct for the inherent axial vapor distribution non-uniformity of the reactor bed. By reducing vapor distribution non-uniformity, a smaller artificial pressure drop can be applied in the perforated plate of the central tube. This results in an overall increase in the measured reactor pressure drop from the reactor inlet flange to the reactor outlet flange.

[0033] Reducing the diameter of the central tube results in a higher velocity head. In some cases, this will become a better match with the velocity head of the sector. Utilizing the improved velocity head balance, this allows the design to impose a lower artificial pressure drop in the perforated plate of the central tube while achieving the same or better vapor distribution within the catalyst bed. This reduces the measured total reactor pressure drop between the reactor inlet flange and the reaction outlet flange.

[0034] In most cases, the end result of an optimized center tube is the same or lower total reactor pressure (reactor flange-flange). In some cases, as the center tube diameter decreases, the pressure drop may increase slightly, but the catalyst volume increases significantly, while maintaining or improving the flow distribution non-uniformity.

[0035] Figures 5 to 6Table 1 illustrates the case study results for this process. It is generally believed that an inherent axial vapor distribution non-uniformity exists along the length of the catalyst bed from top to bottom, and an artificial pressure drop needs to be applied in the perforated plate of the central tube to correct for this non-uniformity, resulting in a significant overall increase in reactor pressure drop between the inlet and outlet. However, the case study demonstrates that, for a given catalyst bed height, reducing the central tube diameter, resulting in an increase in catalyst volume, actually helps improve the vapor flow non-uniformity. Therefore, a smaller artificial pressure drop can be applied in the perforated plate of the central tube. The end result is that, when the central tube diameter is optimized, the total reactor pressure drop increment (flange-flange) can remain the same or negligible increment. The catalyst volume increment can significantly improve aromatics yield. Even though the higher operating reactor pressure due to the increased reactor pressure drop directionally reduces aromatics yield, the catalytic yield performance prediction kinetic model confirms that the aromatics yield loss is insensitive to slight increases in operating pressure, such as... Figure 6 As shown. Generated by the kinetic model for predicting catalytic yield performance. Figure 6 The sensitivity curves confirm that when the diameter of the reactor center tube decreases without causing significant uneven flow distribution, the increase in aromatic yield is sensitive to the increase in catalyst volume. When the center tube diameter is appropriately optimized, the increase in catalyst volume will significantly increase the aromatic yield, while the penalty term for aromatic loss due to the increase in reactor pressure is minimal or non-existent. Figure 5 The sensitivity curves show that for every 1% increase in catalyst volume, the aromatic yield gain is 0.036 wt%, that is, for every 10% increase in catalyst volume, the aromatic yield increases by 0.36 wt%. Figure 6 The sensitivity curves show that for every 0.5 psid increase in pressure, the benefit of increased aromatic yield due to increased catalyst volume decreases by only 0.04 wt%. Table 1 shows that the optimized center tube improves the vapor distribution heterogeneity in reactor 4 from -4.5% to +0.3%, while the reactor pressure differential increases by only 0.28 psid.

[0036] When the openings in the perforated plate of the central tube are shaped to replace the commonly used uniform distribution (e.g., more openings in the low-flow central tube region and fewer openings in the high-flow central tube region), it can potentially further reduce the total reactor pressure drop while maintaining or improving the flow distribution non-uniformity.

[0037] For most operating units in a stacked reactor, the diameter of the reactor center tube is the same to facilitate design (such as avoiding forging the reactor stack shell diameter) and to allow for replacement of common spare center tube components. However, for a given existing stacked reactor shell, maximizing aromatics yield is not necessarily the optimal catalyst utilization.

[0038] Case studies demonstrate that the increased aromatic yield resulting from the catalyst volume increment achieved by the optimized central tube significantly outweighs the loss in aromatic yield caused by a small increase in operating reactor pressure.

[0039] It is well known that reacting C7 alkanes in a feed to form aromatics is very difficult. High reactor temperatures and long residence times in the catalyst bed promote this reaction. Since the reforming reaction is largely endothermic (especially in reactor 1, and less so in reactors 3 and 4), the average catalyst bed temperature in reactors 3 and 4 is higher than that in reactor 1. Increasing the catalyst volume in reactors 3 and 4 by reducing the diameter of the central tube to be smaller than that in reactor 1 provides optimal kinetic conditions for longer residence times and higher operating catalyst bed temperatures to promote the conversion of C7 alkanes to aromatics, thus promoting higher aromatic yields.

[0040] One aspect of the invention relates to a method for increasing the yield of aromatics, or hydrogen, or the reformate octane, or combinations thereof, under a set of selected operating conditions during a reforming process. In one embodiment, the method includes feeding a feed into a reforming reaction zone comprising at least two reforming reactors. A first reforming reactor includes a first shell, a first central tube positioned within the first shell, and a first catalyst disposed between the first shell and the first central tube. The first central tube has a first top connecting section, a first bottom connecting section, a first intermediate section, and a first opening. The first top connecting section has a first top diameter, the first bottom connecting section has a first bottom diameter, the first intermediate section has a first intermediate diameter, and the first opening is sized to allow feed flow and prevent flow of the first catalyst. A second reforming reactor includes a second shell, a second central tube positioned within the second shell, and a second catalyst disposed between the second shell and the second central tube. The second central tube has a top connecting section, a bottom connecting section, and a second intermediate section. The top connecting section has a second top diameter, the bottom connecting section has a second bottom diameter, and the second intermediate section includes a second opening sized to allow feed flow and prevent flow of the second catalyst. The second intermediate section has a second intermediate diameter smaller than the second top diameter, or the second bottom diameter, or both of the second central tube, wherein the second intermediate diameter of the second intermediate section is smaller than the first intermediate diameter of the first intermediate section. The diameters of the first and second shells remain unchanged, the reactor tangent lengths of the first and second shells remain unchanged, and the reactor tangent lengths of the second and second shells remain unchanged. Feed is passed through the first and second catalysts in the first and second reactors to form reaction products, which are then removed from the reforming reaction zone.

[0041] In some implementations, a second central tube replaces the central tube in an existing reformer that includes a top connection section, a bottom connection section, and an intermediate section, wherein the diameters of the top connection section, bottom connection section, and intermediate section in the existing reformer are the same.

[0042] In some implementations, the first top diameter and the first bottom diameter of the first reforming reactor are the same as the second top diameter and the second diameter of the second reforming reactor.

[0043] In some implementations, the ratio of the second intermediate diameter of the second intermediate section to the first intermediate diameter of the first intermediate section is in the range of 0.6 to 0.95.

[0044] In some embodiments, the difference between the first intermediate diameter of the first intermediate section of the first reforming reactor and the second intermediate diameter of the second intermediate section of the second reforming reactor is in the range of 1 inch to 30 inches, and wherein the first intermediate diameter of the first intermediate section is greater than the second intermediate diameter of the second intermediate section.

[0045] In some embodiments, a first central tube or a second central tube, or both, of the reforming reaction zone replaces an existing first central tube or a second existing central tube, or both, of an existing reforming reaction zone comprising at least two reforming reactors. The existing first central tube or the second central tube, or both, of the existing reforming reactor includes a first existing top connection section or a second existing top connection section having a first existing top diameter or a second existing top diameter, a first existing bottom connection section or a second existing bottom diameter having a first existing bottom diameter or a second existing bottom diameter, and a first intermediate section or a second intermediate section having a first existing intermediate diameter or a second existing intermediate diameter. The ratio of the first intermediate diameter of the first intermediate section or the second intermediate section of the reforming reaction zone to the first existing intermediate diameter of the intermediate section of the existing first central tube or the second existing central tube, or both, of the existing reforming reactor is in the range of 0.6 to 0.95.

[0046] In some embodiments, the first top diameter, first bottom diameter, and first intermediate diameter of the first reforming reactor are the same. In some embodiments, the first intermediate diameter is different from the first top diameter, or the first bottom diameter, or both.

[0047] In some implementations, the intermediate diameter of the second (or subsequent) reforming reactor differs from the top diameter of the top connection or the bottom diameter of the bottom connection, or both.

[0048] In some embodiments, the first reforming reactor further includes a first sector comprising a front, a back, and opposing sides, the first sector being positioned between a first shell and a first central tube, wherein a first catalyst is disposed between the front of the first sector and the first central tube; or wherein the second reforming reactor further includes a second sector comprising a front, a back, and opposing sides, the second sector being positioned between a second shell and a second central tube, wherein a second catalyst is disposed between the front of the second sector and the second central tube; or both.

[0049] In some embodiments, the layer of the first intermediate section of the first central tube has a non-uniform pattern with a first opening, or the layer of the second intermediate section of the second central tube has a non-uniform pattern with a second opening, or both.

[0050] In some embodiments, the non-uniform pattern of the first opening includes a region of the first opening near the bottom of the central tube that is smaller than the region of the first opening near the top of the central tube; or the non-uniform pattern of the second opening includes a region of the second opening near the bottom of the central tube that is smaller than the region of the second opening near the top of the central tube; or both.

[0051] In some embodiments, the reforming reaction zone includes at least one additional reforming reactor, the at least one additional reforming reactor including at least one additional shell, at least one additional central tube positioned within the at least one additional shell, and at least one additional catalyst disposed between the at least one additional shell and the at least one additional central tube, the at least one additional central tube having a top connecting section, a bottom connecting section, and an intermediate section, the top connecting section having an additional top diameter, the bottom connecting section having an additional bottom diameter, and the intermediate section having an additional intermediate diameter, the intermediate section of the at least one additional reforming reactor including an additional opening sized to allow feed flow and prevent flow of the at least one additional catalyst, the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor being smaller than a first top diameter, or a first bottom diameter, or both of the intermediate section of the at least one additional reforming reactor, wherein the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is smaller than a first top diameter of a first intermediate section, or a second intermediate diameter of a second intermediate section, or both, wherein the diameter of the at least one additional shell remains constant, and wherein the reactor tangential length of the at least one additional shell remains constant.

[0052] Figures 1 to 3An embodiment of a reforming reactor 100 according to the invention is illustrated. The reactor shell 105 is shown having a sector 110. The dashed line indicates the location of the original central tube 115 that has been replaced (or redesigned in a new reactor). The original catalyst volume 120 is contained between the sector 110 and the original central tube 115. The redesigned central tube 125 provides an additional catalyst volume 130. The diameter of the central tube at the top (2RT) and / or the diameter of the central tube at the bottom (2RB) is greater than the diameter of the middle portion (2RI). Between the replaced original central tube 115 and the redesigned central tube 125, there are a top transition 135 and a bottom transition 140.

[0053] The existing center tube support 145 is replaced by a new center tube support 150. This allows the existing connections at the top and / or bottom to be maintained.

[0054] Figure 4 An example is given of a method for optimizing the diameter of the central tube in the reforming reactor zone.

[0055] In one implementation, aromatic yield can be optimized by determining an optimized center tube diameter. A first step 400 involves reducing the intermediate diameter of the second center tube by a selected amount (X%) of the intermediate diameter of the first center tube. In the next step 405, the increased catalyst volume in the second reforming reactor is calculated based on the reduced intermediate diameter of the second center tube. In step 410, an aromatic yield increment is determined using a catalytic yield performance prediction model, based on the increased catalyst volume, the previous operating reactor pressure, and the original reactor inlet temperature. In step 415, a modified reactor pressure is calculated using the new physical properties of the gas from the catalytic yield performance prediction model in step 410 and the reduced center tube diameter. In step 420, a new aromatic yield increment is determined using the catalytic yield performance prediction model, based on the increased catalyst volume and modified reactor conditions, such as new flow pressure and physical properties. In step 425, the new aromatic yield increment and reactor flow distribution are compared with the previous aromatic yield increment. If the new aromatic yield increment is greater than the previous aromatic yield increment, the process is repeated by returning to step 400 and selecting a larger catalyst volume increment. If the new aromatic yield increment is less than the previous aromatic yield increment, the previously selected reduced center tube and its corresponding catalyst volume increment provide the optimal aromatic yield increment and are selected in step 430.

[0056] This optimization process can be used to optimize the diameter of the central tubes of the first, second, third, and fourth (or more) reactors.

[0057] Case Studies

[0058] Case studies show that improvements in aromatics yield are sensitive to catalyst volume increments; for example, a 10% increase in volume results in an aromatics yield increase of +0.36% by weight. Figure 5 As shown.

[0059] Table 1 shows that for an increase of 8.9% by volume in catalyst volume obtained by reducing the diameter of the reactor center tube from the original diameter, the reactor pressure drop increment increased by 0.28 psid from 2.5 psid to 2.78 psid, while the vapor distribution unevenness improved from -4.5% to 0.3%.

[0060] Compared to a 0.024 wt% loss in aromatics yield, the gain in aromatics yield due to the increase in catalyst volume was 0.32 wt%. The final gain in aromatics yield was 0.296 wt% due to the catalyst volume change caused by the optimized center tube.

[0061] Table 1

[0062]

[0063]

[0064] Specific implementation plan

[0065] While the following description is presented in conjunction with specific embodiments, it should be understood that the description is intended to be illustrative and not to limit the scope of the foregoing description and the appended claims.

[0066] A first embodiment of the present invention is a method for increasing the yield of aromatics, or hydrogen, or the octane number of reformate, or a combination thereof, under a set of selected operating conditions during a reforming process. The method includes: supplying feed to a reforming reaction zone comprising at least two reforming reactors; the first reforming reactor comprising a first shell, a first central tube positioned within the first shell, and a first catalyst disposed between the first shell and the first central tube; the first central tube having a first top connecting section, a first bottom connecting section, and a first intermediate section; the first top connecting section having a first top diameter; the first bottom connecting section having a first bottom diameter; the first intermediate section having a first intermediate diameter; the first intermediate section including a first opening sized to allow feed flow and prevent first catalyst flow; and a second reforming reactor comprising a second shell, a second central tube positioned within the second shell, and a catalyst disposed between the second shell and the first central tube. A second catalyst between two central tubes, the second central tube having a second top connecting section, a second bottom connecting section, and a second intermediate section, the second top connecting section having a second top diameter, the second bottom connecting section having a second bottom diameter, the second intermediate section including a second opening, the second opening being sized to allow feed flow and prevent second catalyst flow, the second intermediate section having a second intermediate diameter smaller than the second top diameter, or the second bottom diameter, or both of the second central tube, wherein the second intermediate diameter of the second intermediate section is smaller than the first intermediate diameter of the first intermediate section, wherein the diameter of the first shell remains unchanged and the diameter of the second shell remains unchanged, and wherein the reactor tangential length of the first shell remains unchanged and the reactor tangential length of the second shell remains unchanged; the feed is passed through the first catalyst and the second catalyst in the first reactor and the second reactor to form reaction products; and the reaction products are removed from the reforming reaction zone. One embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein a second central tube replaces the central tube in an existing reforming reactor that includes a top connecting section, a bottom connecting section, and an intermediate section, wherein the diameters of the top connecting section, the bottom connecting section, and the intermediate section of the existing reforming reactor are the same. Another embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the first top diameter and the first bottom diameter of the first reforming reactor are the same as the second top diameter and the second bottom diameter of the second reforming reactor. Another embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the ratio of the second intermediate diameter of the second intermediate section to the first intermediate diameter of the first intermediate section is in the range of 0.6 to 0.95.One embodiment of the present invention is one, any one, or all of the embodiments from the previous embodiments to the first embodiment in this paragraph, wherein the difference between the first intermediate diameter of the first intermediate section of the first reforming reactor and the second intermediate diameter of the second intermediate section of the second reforming reactor is in the range of 1 in to 20 in, and wherein the first intermediate diameter of the first intermediate section is greater than the second intermediate diameter of the second intermediate section. One embodiment of the present invention is one, any one, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein a first central tube or a second central tube or both of the reforming reaction zone replaces a first existing central tube or a second existing central tube or both of the existing reforming reaction zone comprising at least two reforming reactors. The first central tube or the second central tube or both of the existing reforming reactors comprises a first existing top connection section or a second existing top connection section having a first existing top diameter or a second existing top diameter, a first existing bottom connection section or a second existing bottom diameter having a first existing bottom diameter or a second existing bottom diameter, and a first intermediate section or a second intermediate section having a first existing intermediate diameter or a second existing intermediate diameter. The ratio of the first intermediate diameter or the second intermediate diameter of the first replacement intermediate section or the second replacement intermediate section of the reforming reaction zone to the first existing intermediate diameter or the second existing intermediate diameter of the intermediate section of the first existing central tube or the second existing central tube or both of the existing reforming reactors is in the range of 0.6 to 0.95. One embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the first top diameter, the first bottom diameter, and the first intermediate diameter of the first reforming reactor are the same. Another embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the first reforming reactor further includes a first sector, the first sector including a front side, a back side, and opposing sides, the first sector being positioned between a first shell and a first central tube, wherein a first catalyst is disposed between the front side of the first sector and the first central tube; or wherein the second reforming reactor further includes a second sector, the second sector including a front side, a back side, and opposing sides, the second sector being positioned between a second shell and a second central tube, wherein a second catalyst is disposed between the front side of the second sector and the second central tube; or both. Another embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the layer of the first intermediate section of the first central tube has a non-uniform pattern with a first opening, or the layer of the second intermediate section of the second central tube has a non-uniform pattern with a second opening, or both.One embodiment of the invention is one, any one, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the non-uniform pattern of the first opening includes a region of the first opening near the bottom of the central tube that is smaller than the region of the first opening near the top of the central tube; or the non-uniform pattern of the second opening includes a region of the second opening near the bottom of the central tube that is smaller than the region of the second opening near the top of the central tube; or both. Another embodiment of the invention is one, any one, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the reforming reaction zone includes at least one additional reforming reactor, the at least one additional reforming reactor including at least one additional shell, at least one additional central tube positioned within the at least one additional shell, and at least one additional catalyst disposed between the at least one additional shell and the at least one additional central tube, the at least one additional central tube having a top connecting section, a bottom connecting section, and a middle section, the top connecting section having an additional top diameter, the bottom connecting section having an additional bottom diameter, and the middle section having an additional middle section. The intermediate section of the at least one additional reforming reactor includes an additional opening sized to allow feed flow and prevent flow of the at least one additional catalyst. The additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is smaller than a first top diameter, or a first bottom diameter, or both of the intermediate section of the at least one additional reforming reactor. The additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is smaller than a first intermediate diameter of a first intermediate section, or a second intermediate diameter of a second intermediate section, or both. The diameter of the at least one additional shell remains constant, and the reactor tangential length of the at least one additional shell remains constant.One embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, and further includes optimizing aromatics yield by means of the following steps: determining an optimized center tube diameter; 1) reducing the second intermediate diameter of the second center tube by a selected amount of the first intermediate diameter of the first center tube; 2) calculating the increased catalyst volume in the second reforming reactor based on the reduced second intermediate diameter of the second center tube; 3) determining the aromatics yield increment based on the increased catalyst volume, the previous operating reactor pressure, and the original reactor inlet temperature using a catalytic yield performance prediction model; 4) based on 5) Calculate the modified reactor pressure using the reduced second intermediate diameter of the second central tube; 6) Determine the new aromatic yield increment using a catalytic yield performance prediction model based on the increased catalyst volume and the modified reactor pressure; 7) Compare the new aromatic yield increment with the previous aromatic yield increment; a) If the new aromatic yield increment is less than the previous aromatic yield increment, select the second intermediate diameter of the second central tube as the first intermediate diameter of the first central tube minus the selected amount; b) If the new aromatic yield increment is greater than the previous aromatic yield increment, return to step 1) and increase the selected amount of the first intermediate diameter of the first central tube.

[0067] A second embodiment of the invention is a method for increasing the yield of aromatics, or hydrogen, or the reformate octane, or combinations thereof, under a set of selected operating conditions during a reforming process. The method includes feeding a reforming reaction zone comprising at least two reforming reactors. A first reforming reactor includes a first shell, a first sector, and a first central tube. The first sector includes a front side, a back side, and opposing sides. The first sector is positioned between the first shell and the first central tube, and a first catalyst is disposed between the first sector and the first central tube. The first central tube has a first top connecting section, a first bottom connecting section, and a first intermediate section. The first top connecting section has a first top diameter, the first bottom connecting section has a first bottom diameter, and the first intermediate section has a first intermediate diameter. The first intermediate section includes a first opening sized to allow feed flow and prevent first catalyst flow. A second reforming reactor includes a second shell, a second sector, and a second central tube. The second sector includes a front side, a back side, and opposing sides. The second sector is positioned between the second shell and the second central tube. The second catalyst is disposed between the second sector and the second central tube. The second central tube has a second top connecting section, a second bottom connecting section, and a second intermediate section. The second top connecting section has a second top diameter, the second bottom connecting section has a second bottom diameter, and the second intermediate section includes a second opening sized to allow feed flow and prevent the second catalyst flow. The second intermediate section has a second intermediate diameter smaller than the second top diameter, or the second bottom diameter, or both of the second central tube. The second intermediate diameter of the second intermediate section is smaller than the first intermediate diameter of the first intermediate section. The diameters of the first and second shells remain unchanged, and the reactor tangent lengths of the first and second shells remain unchanged. The ratio of the second intermediate diameter of the second intermediate section to the first intermediate diameter of the first intermediate section is in the range of 0.6 to 0.95. The feed is passed through the first and second catalysts in the first and second reactors to form reaction products. The reaction products are then removed from the reforming reaction zone. One embodiment of the present invention is any one or all of the embodiments described in the preceding embodiments to the second embodiments described in this paragraph, wherein a second central tube replaces the central tube in an existing reforming reactor that includes a top connecting section, a bottom connecting section, and an intermediate section, wherein the diameters of the top connecting section, the bottom connecting section, and the intermediate section of the existing reforming reactor are the same. Another embodiment of the present invention is any one or all of the embodiments described in the preceding embodiments to the second embodiments described in this paragraph, wherein the first top diameter and the first bottom diameter of the first reforming reactor are the same as the second top diameter and the second bottom diameter of the second reforming reactor.One embodiment of the present invention is one, any one, or all of the embodiments described in the preceding embodiments to the second embodiments described in this paragraph, wherein the difference between the first intermediate diameter of the first intermediate section of the first reforming reactor and the second intermediate diameter of the second intermediate section of the second reforming reactor is in the range of 1 in to 20 in, and wherein the first intermediate diameter of the first intermediate section is greater than the second intermediate diameter of the second intermediate section. One embodiment of the present invention is one, any one, or all of the embodiments described in the preceding embodiments to the second embodiments described in this paragraph, wherein a first central tube or a second central tube or both of the reforming reaction zone replaces a first existing central tube or a second existing central tube or both of the existing reforming reaction zone comprising at least two reforming reactors. The first central tube or the second central tube or both of the existing reforming reactors comprises a first existing top connection section or a second existing top connection section having a first existing top diameter or a second existing top diameter, a first existing bottom connection section or a second existing bottom connection section having a first existing bottom diameter or a second existing bottom diameter, and a first intermediate section or a second intermediate section having a first existing intermediate diameter or a second existing intermediate diameter, wherein the ratio of the first intermediate diameter or the second intermediate diameter of the first replacement intermediate section or the second replacement intermediate section of the reforming reaction zone to the first existing intermediate diameter or the second existing intermediate diameter of the intermediate section of the first existing central tube or the second existing central tube or both of the existing reforming reactors is in the range of 0.6 to 0.95. One embodiment of the present invention is one, any one, or all of the embodiments described in the preceding embodiments to the second embodiments described in this paragraph, wherein the layer of the first intermediate section of the first central tube has a non-uniform pattern of a first opening, or the layer of the second intermediate section of the second central tube has a non-uniform pattern of a second opening, or both; and wherein the non-uniform pattern of the first opening includes a region of the first opening near the bottom of the central tube that is smaller than the region of the first opening near the top of the central tube; or the non-uniform pattern of the second opening includes a region of the second opening near the bottom of the central tube that is smaller than the region of the second opening near the top of the central tube; or both.One embodiment of the invention is one, any one, or all of the embodiments described in the preceding to the second embodiments in this paragraph, wherein the reforming reaction zone includes at least one additional reforming reactor, the at least one additional reforming reactor including at least one additional shell, at least one additional sector, the at least one additional sector including a front, a back, and opposing sides, the at least one additional sector being positioned between the at least one additional shell and the at least one additional central tube, and at least one additional catalyst being disposed between the at least one additional sector and the at least one additional central tube, the at least one additional central tube having a top connecting section, a bottom connecting section, and a middle section, the top connecting section having an additional top diameter, the bottom... The connecting section has an additional bottom diameter, the intermediate section has an additional intermediate diameter, the intermediate section of the at least one additional reforming reactor includes an additional opening, the additional opening is sized to allow feed flow and prevent the at least one additional catalyst flow, the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is smaller than a first top diameter, or a first bottom diameter, or both of the intermediate section of the at least one additional reforming reactor, wherein the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is smaller than a first intermediate diameter of a first intermediate section, or a second intermediate diameter of a second intermediate section, or both, wherein the diameter of the at least one additional shell is constant, and wherein the reactor tangential length of the at least one additional shell is constant. One embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the second embodiments described in this paragraph, and further includes optimizing aromatics yield by means of the following steps: determining an optimized center tube diameter; 1) reducing the second intermediate diameter of the second center tube by a selected amount of the first intermediate diameter of the first center tube; 2) calculating the increased catalyst volume in the second reforming reactor based on the reduced second intermediate diameter of the second center tube; 3) determining the aromatics yield increment using a catalytic yield performance prediction model based on the increased catalyst volume, the previous operating reactor pressure, and the original reactor inlet temperature; 4) based on 5) Calculate the modified reactor pressure using the reduced second intermediate diameter of the second central tube; 6) Determine the new aromatic yield increment using a catalytic yield performance prediction model based on the increased catalyst volume and the modified reactor pressure; 7) Compare the new aromatic yield increment with the previous aromatic yield increment; a) If the new aromatic yield increment is less than the previous aromatic yield increment, select the second intermediate diameter of the second central tube as the first intermediate diameter of the first central tube minus the selected amount; b) If the new aromatic yield increment is greater than the previous aromatic yield increment, return to step 1) and increase the selected amount of the first intermediate diameter of the first central tube.

[0068] Although no further detailed description has been provided, it is believed that those skilled in the art will be able to make full use of the invention by employing the foregoing description and will be able to readily identify the essential features of the invention without departing from its spirit and scope, and to make various changes and modifications to adapt it to various uses and situations. Therefore, the foregoing preferred embodiments should be understood as illustrative only and not as limiting the remainder of this disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0069] In the foregoing, all temperatures are expressed in degrees Celsius, and all portions and percentages are by weight unless otherwise specified.

Claims

1. A method for increasing the yield of aromatics, or hydrogen, or reformate octane, or combinations thereof, during a reforming process under a set of selected operating conditions, said method comprising: A feed is provided to a reforming reaction zone comprising at least two reforming reactors. A first reforming reactor includes a first shell, a first central tube positioned within the first shell, and a first catalyst disposed between the first shell and the first central tube. The first central tube has a first top connecting section, a first bottom connecting section, and a first intermediate section. The first top connecting section has a first top diameter, the first bottom connecting section has a first bottom diameter, and the first intermediate section has a first intermediate diameter. The first intermediate section includes a first opening sized to allow feed flow and prevent the first catalyst from flowing. A second reforming reactor includes a second shell, a second central tube positioned within the second shell, and a catalyst disposed between the second shell and the second central tube. The second catalyst, the second central tube having a second top connecting section, a second bottom connecting section and a second intermediate section, the second top connecting section having a second top diameter, the second bottom connecting section having a second bottom diameter, the second intermediate section including a second opening, the second opening being sized to allow feed flow and prevent the second catalyst from flowing, the second intermediate section having a second intermediate diameter smaller than the second top diameter, or the second bottom diameter, or both of the second central tube, wherein the second intermediate diameter of the second intermediate section is smaller than the first intermediate diameter of the first intermediate section, wherein the diameter of the first shell remains unchanged and the diameter of the second shell remains unchanged, and wherein the reactor tangential length of the first shell remains unchanged and the reactor tangential length of the second shell remains unchanged; The feed is passed through the first catalyst and the second catalyst in the first reactor and the second reactor to form reaction products; as well as Remove the reaction products from the reforming reaction zone.

2. The method of claim 1, wherein the second central tube replaces the central tube in the existing reforming reactor that includes a top connecting section, a bottom connecting section, and a middle section, wherein the diameters of the top connecting section, the bottom connecting section, and the middle section of the existing reforming reactor are the same.

3. The method according to any one of claims 1 to 2, wherein the first top diameter and the first bottom diameter of the first reforming reactor are the same as the second top diameter and the second bottom diameter of the second reforming reactor.

4. The method according to any one of claims 1 to 2, wherein the ratio of the second intermediate diameter of the second intermediate segment to the first intermediate diameter of the first intermediate segment is in the range of 0.6 to 0.

95.

5. The method according to any one of claims 1 to 2, wherein the difference between the first intermediate diameter of the first intermediate section of the first reforming reactor and the second intermediate diameter of the second intermediate section of the second reforming reactor is in the range of 1 in to 20 in, and wherein the first intermediate diameter of the first intermediate section is greater than the second intermediate diameter of the second intermediate section.

6. The method according to any one of claims 1 to 2, wherein the first central tube or the second central tube or both of the reforming reaction zone replaces the first existing central tube or the second existing central tube or both of an existing reforming reaction zone comprising at least two reforming reactors, wherein the first central tube or the second central tube or both of the existing reforming reactor comprises a first existing top connection section or a second existing top connection section having a first existing top diameter or a second existing top diameter, a first existing bottom connection section or a second existing bottom connection section having a first existing bottom diameter or a second existing bottom diameter, and a first intermediate section or a second intermediate section having a first existing intermediate diameter or a second existing intermediate diameter, wherein the ratio of the first intermediate diameter or the second intermediate diameter of the first replacement intermediate section or the second replacement intermediate section of the reforming reaction zone to the first existing intermediate diameter or the second existing intermediate diameter of the intermediate section of the first existing central tube or the second existing central tube or both of the existing reforming reactor is in the range of 0.6 to 0.

95.

7. The method according to any one of claims 1 to 2, wherein the first reforming reactor further comprises a first sector, the first sector comprising a front side, a back side, and opposite sides, the first sector being positioned between a first shell and a first central tube, wherein the first catalyst is disposed between the front side of the first sector and the first central tube; or wherein the second reforming reactor further comprises a second sector, the second sector comprising a front side, a back side, and opposite sides, the second sector being positioned between a second shell and a second central tube, wherein the second catalyst is disposed between the front side of the second sector and the second central tube; or both.

8. The method according to any one of claims 1 to 2, wherein the layer of the first intermediate section of the first central tube has a non-uniform pattern of the first opening, or the layer of the second intermediate section of the second central tube has a non-uniform pattern of the second opening, or both.

9. The method according to any one of claims 1 to 2, wherein the reforming reaction zone comprises at least one additional reforming reactor, the at least one additional reforming reactor comprising at least one additional shell, at least one additional central tube positioned within the at least one additional shell, and at least one additional catalyst disposed between the at least one additional shell and the at least one additional central tube, the at least one additional central tube having a top connecting section, a bottom connecting section, and an intermediate section, the top connecting section having an additional top diameter, the bottom connecting section having an additional bottom diameter, the intermediate section having an additional intermediate diameter, the intermediate section of the at least one additional reforming reactor comprising an additional opening sized to allow feed flow and prevent flow of the at least one additional catalyst, the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor being smaller than the first top diameter, or the first bottom diameter, or both of the intermediate section of the at least one additional reforming reactor, wherein the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is smaller than the first top diameter of the first intermediate section, or the second intermediate diameter, or both of the second intermediate section, wherein the diameter of the at least one additional shell remains constant, and wherein the reactor tangential length of the at least one additional shell remains constant.

10. The method according to any one of claims 1 to 2, further comprising optimizing the aromatic yield by determining an optimized central tube diameter: 1) Reduce the second intermediate diameter of the second central tube to a selected amount equal to the first intermediate diameter of the first central tube; 2) Calculate the increased catalyst volume in the second reforming reactor based on the reduced second intermediate diameter of the second central tube; 3) The incremental aromatic yield was determined using a catalytic yield performance prediction model based on the increased catalyst volume, the previous operating reactor pressure, and the original reactor inlet temperature. 4) Calculate the modified reactor pressure based on the reduced second intermediate diameter of the second central tube; 5) Using a catalytic yield performance prediction model, determine the new aromatic yield increment based on the increased catalyst volume and the modified reactor pressure; 6) Compare the new aromatic yield increment with the previous aromatic yield increment; a) If the new aromatic yield increment is less than the previous aromatic yield increment, then the second intermediate diameter of the second central tube is selected as the first intermediate diameter of the first central tube minus the selected amount. b) If the new aromatic yield increment is greater than the previous aromatic yield increment, return to step 1) and increase the selected amount of the first intermediate diameter of the first central tube.

Images