Support structure for supporting catalyst and catalytic reformer

Abstract

Invention relates to a support structure (3) for supporting catalyst and a catalytic reformer (1) to convert hydrocarbon feedstock into product gas, the catalytic reformer comprising a reactor shell (2) forming an enclosure and defining an interior space where catalyst is accommodated, and a support structure (3) for supporting catalyst, the support structure (3) comprises - a grid (31) provided with a plurality of openings (32) that allows the hydrocarbon feedstock to flow through, - a cooling fluid circulation (33) within the grid (31) to provide a cooling membrane panel (34), - the grid (31) comprises an arrangement of tubes (35) to provide the cooling fluid circulation (33), the tubes (35) being connected to each other by fins (36).

Description

Support structure for supporting catalyst and catalytic reformerTechnical field

[0001] The present invention relates to a support structure for supporting catalyst within a reactor in a catalytic reformer. The catalytic reformer is configured to convert hydrocarbon feedstock into product gas. The catalytic reformer may comprise a reactor shell forming an enclosure having a circular I polygonal cross section and defining an interior space for catalyst to be accommodated, a support structure for supporting the catalyst and a feeding device. The present invention relates to an improved reactor system and catalyst configuration for the production of synthesis gas (syngas) from biomass using reactant in gas phase, such as steam and oxygen. The invention specifically concerns an enhanced support structure for supporting catalyst within the reactor, the support structure comprises;- a grid provided with a plurality of openings that allows hydrocarbon feedstock to flow through,- a cooling fluid circulation within the grid to provide a cooling membrane panel.The invention concerns basically a downward-flow type catalytic reformer reactor with enhanced catalyst support structure, designed to improve catalyst stability, thermal efficiency, and product gas yield. Especially the present invention relates to catalytic reformer according to the preamble of claim 1 and a catalytic reformer according to the preamble of claim 10.Background art

[0002] Catalytic reforming of hydrocarbon is a well-established process for converting hydrocarbon feedstock such as renewable carbonaceous materials like biomass into synthesis gas composed primarily of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2). Such gas can be utilized in a wide range of downstream applications including Fischer-Tropsch synthesis, methanol production, and hydrogen generation for fuel cells.

[0003] Conventional reforming reactors are often configured as fluidized-bed, fixed-bed, or entrained-flow systems. Among these, downward-flow configurations — in which hydrocarbon feedstock and reforming agents such as steam and oxygen descend throughthe reactor under gravity — are advantageous due to improved solids handling, controlled residence time, and facilitated removal of ash or char residues. In such systems, catalytic reforming typically occurs at temperatures between 700 °C and 950 °C, and at pressures ranging from atmospheric to about 10 bar.

[0004] A carefully controlled ratio of steam to carbon (S / C), generally in the range of 0.8 to 2.0 mol / mol, is used to suppress coke formation and drive the reforming reactions. A limited supply of oxygen (or air), controlled by the oxygen-to-carbon (O / C) ratio, typically 0.1 to 0.4 mol / mol, provides the necessary heat through partial oxidation reactions. The synthesis gas composition is influenced by these operating parameters as well as by the nature and performance of the catalyst system.

[0005] Known catalytic systems typically utilize nickel (Ni) or noble metal-based catalysts (e.g., Rh, Pt) supported on thermally stable materials such as alumina, zirconia, or cerium oxide, sometimes promoted with alkali or alkaline earth metals to enhance resistance to deactivation. These catalysts facilitate endothermic steam reforming reactions as well as exothermic partial oxidation and water-gas shift reactions.

[0006] However, as disclosed in WO 00 / 76653 A1, WO 2007 / 071925 A1, and KR 2013 / 0034120 A, many prior art systems suffer from limitations in catalyst support structure integrity, particularly under thermal cycling or in the presence of biomass-derived impurities such as alkali metals, sulphur, and chlorine compounds. Catalyst supports structure may undergo sintering, phase transformation, or structural collapse, which reduces reforming efficiency, increases pressure drop, and shortens catalyst life.

[0007] Moreover, in downward-flow reactors, ensuring uniform contact between the hydrocarbon feedstock and the catalyst surface is critical. A catalyst support structure that lacks mechanical robustness or exhibits poor thermal conductivity may cause channelling, localized hot spots, and inefficient conversion. These issues are exacerbated in large-scale or continuous operation systems.

[0008] Thus, there exists a need for an improved catalyst support structure that maintains high surface area, thermal and mechanical stability, and resistance to deactivation during long-term operation in downward-flow catalytic reformers. The present invention addresses this need by providing an improved support architecture that overcomes the deficiencies of the prior art.

[0009] An object of the invention is to provide a support structure for supporting catalyst in a catalytic reformer and a catalytic reformer in which the performance is considerably improved compared to the prior art solutions.Disclosure of the Invention

[0010] Objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.

[0011] According to an embodiment of the invention it is provided a support structure for supporting catalyst within a reactor, the support structure comprises- a grid provided with a plurality of openings that allows hydrocarbon feedstock to flow through,- a cooling fluid circulation within the grid to provide a cooling membrane panel, - the grid comprises an arrangement of tubes to provide the cooling fluid circulation, the tubes being connected to each other by fins. According to an embodiment it is provided a catalytic reformer to convert hydrocarbon feedstock into product gas, the catalytic reformer comprising a reactor shell forming an enclosure and defining an interior space where catalyst is accommodated. In general the main structure of catalytic reformer comprises an uncooled steel casing with refractory lining, a feeding device to feed a reactant in gas phase and the support structure for supporting catalyst to be used. The catalytic reformer may be configured of several stages of feeding device I support structure pairs placed successively in the flow direction of the hydrocarbon feedstock. The reactant in gas phase comprises one or more reforming agents, including steam and / or CO2, and may further comprise an oxidizing agent, such as oxygen. The reactant in gas phase preferably comprises a mixture of oxygen and steam, or a mixture of oxygen, steam and CO2. Hereinafter, the reactant in gas phase is referred to as reactant gas. According to an embodiment of the invention the catalytic reformer comprises a number of support structures, the number being at least one, but preferably two, three or more support structures successively in the flow direction of the hydrocarbon feedstock. The support structure further comprises an inlet header configured to receive cooling fluid and an outlet header configured to discharge the cooling fluid, the inlet header and the outlet header are spaced apart in the flow direction of the hydrocarbon feedstock. Preferable the catalyst is in a granular form, and it is nickel based. The granule particle size issuitably about 10 - 35 mm in diameter. Catalyst material is loaded inside catalyst reformer on top of the support structure or via hatches provided in the reactor shell.

[0012] The support structure is made as the cooling membrane panel comprising the cooling fluid circulation to enable controlling temperature and thermal movements caused by temperature differences. It also reduces challenges that high temperature present to material selection and thus enables utilization of lower grade steels. The grid comprises an arrangement of tubes being connected to each other by fins that provides suitable spacing for the tubes and the fins also enable to configure plurality of openings between the tubes that allow the hydrocarbon feedstock to flow through. According to an embodiment of the invention the support structure extending outside the reactor shell is enclosed in a heat insulation. The heat insulation can be applied around a support of the cooling membrane panel as well as around steel casing at a support level i.e. at the level where the cooling membrane panel is attached to the reactor shell I casing. The heat insulation of support level allows to maintain similar temperature in casing (at the support level) as in the cooling membrane panel and forcing differential thermal expansion to take place in intact steel casing area rather than at an area of tube penetrations. The heat insulation is also used to protect personnel from hot surfaces.

[0013] According to an embodiment of the invention the arrangement of tubes comprises a first group of tubes, each of the tubes of the first group of tubes has a first end and a second end, and is dimensioned to extend throughout the interior space of the reactor shell such that both the first end and the second end are located outside the reactor shell. This feature defines a basic configuration of the tubes in relation to the reactor shell. The tube ends are located outside the reactor shell. According to an embodiment of the invention the first group of tubes are configured in a plane transverse to a flow direction of the hydrocarbon feedstock, and the plurality of openings are formed on the fins that connect the first group of tubes. The arrangement of tubes is utilized to achieve product gas flow through the support structure and an effective circulation of cooling fluid and a stiff construction. The fins determine the spacing of the tubes in a direction traverse to the flow direction which corresponds in most cases that the first group of tubes are configured in a horizontal plane.

[0014] According to an embodiment of the invention the arrangement of tubes further comprises a second group of tubes in a stacked configuration along the flow direction of the hydrocarbon feedstock. As a typical diameter of catalytic reformer can be several meters, the cooling membrane panel needs to be stiff enough to be used in larger scale units. This is done by adding cooled tubes on top of each other as a stack and connectingthem with fins or directly to each other. According to an embodiment of the invention the stacked configuration comprises one, two, three, four or more tubes coupled to the tube of the first group of tubes or connected to the fin that connects two first group of tubes. This feature has a direct effect on the bending stiffness of the cooling membrane panel and the support structure. The bending stiffness can be calculated via dimensions, and in calculation of a second moment of area, the cooling membrane panel thickness i.e. stacked tubes thickness to the third power is the decisive factor. The stacked tubes can be on top or bottom side of membrane panel, but arrangement is more convenient if they are on the bottom side. Especially the catalyst material handling is easier, if the stacked tubes are on the bottom side the stack pointing downwards. Cooling media flowing inside the arrangement of tubes of the cooling membrane panel can vary based on what is available. Typically steam or water would be used if it's available but other sources can be considered.

[0015] According to an embodiment of the invention, the grid, in the width direction, there is every second, third or fourth tube arranged as the stacked configuration. In the arrangement of tubes, it is practical if there is a combination of first group of tubes (in planar configuration) and second group of tubes (in stacked configuration). The total weight of the grid remains on a reasonable level, bending stiffness can be designed on proper level and still the heat exchange properties are good.

[0016] According to an embodiment of the invention the tubes are connected to each other with fins or other plate-like construction that determines the spacing between tubes. Further, according to an embodiment, the openings in the fins are provided with perforated cover plates to prevent catalyst to fall down through the openings, the cover plates are perforated to prevent particle size of about 10 - 35 mm to penetrate the openings. By suitable dimension of the perforations in the cover plates both flow resistance can be predetermined and the grid properties can easily be matched with catalyst particle size. To allow gas flow through panel, fins are perforated (holes or longer slots). As particle size is quite small, a heat resisting wire mesh or perforated cover plates is added between support and catalyst layer to prevent catalyst material to go through support.

[0017] According to an embodiment of the invention the catalytic reformer comprises a number of support structures, the number being at least one, but preferably two, three or more support structures successively in the flow direction of the hydrocarbon feedstock. These successive support structures I oxygen steam feeding devices form a multistage catalytic reformer that is capable of performing its function in an efficient way and with efficient yield.

[0018] According to an embodiment of the invention the flow direction of the cooling fluid circulation in successive support structures is arranged to be reverse to the flow direction of the hydrocarbon feedstock. This feature enables efficient heat transfer within the catalytic reformer. According to an embodiment of the invention the flow direction of the cooling fluid circulation has been arranged from bottom to top in a vertically advancing manner, so that the inlet header is at a lower elevation than the outlet header for the support structure. In a preferred embodiment, a natural circulation is utilized so that the flow direction of the cooling fluid circulation in successive support structures has been arranged from bottom to top in a vertically advancing natural circulation manner, so that the inlet header is at a lower elevation than the outlet header for the support structure. Thus, the circulating cooling fluid as it becomes heated, it raises upwards due to a natural density change.

[0019] According to an embodiment of the invention the support structure is attached to the reactor shell by means of welding. As the process conditions within the catalyst reformer are very harsh, the integrity of the structure in overall is important so that operating the plant comprising the catalytic reformer is safe and it withstands all the loads caused by the operation.

[0020] According to an embodiment of the invention the heat insulation encloses a continuous volume around the reactor shell. According to an embodiment of the invention the support structure extending outside the reactor shell enclosed in the heat insulation is provided with an air-cooling system. These heat insulations improve the controllability of the catalytic reformer; it improves heat efficiency and makes the surrounding areas near the catalytic reformer safe to any personnel operating the catalyst reformer. Catalyst support structure can be also refractory lined to control heat transfer.

[0021] These features above provide an effect by means of which the catalytic reformer performance is considerably improved.

[0022] The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims.Brief Description of Drawings

[0023] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in which:Figure 1 illustrates an overall outside view of a catalytic reformer,Figure 2A and 2B illustrates a Y according to another embodiment of the invention,Figure 3 illustrates schematically a side view according to still another embodiment of the invention,Figure 4 illustrates an isometric cross section of a subsequence according to still another embodiment of the invention,Figure 5A and 5B illustrates top views of the support structure according to still another embodiment of the invention,Figure 6 illustrates an isometric cross section of a subsequence of the support structure according to still another embodiment of the invention,Figure 7 illustrates a top view of a grid according to still another embodiment of the invention.Detailed Description of Drawings

[0024] Figure 1 depicts schematically a catalytic reformer 1 to convert hydrocarbon feedstock into product gas, the catalytic reformer comprising a reactor shell 2 forming an enclosure and defining an interior space where catalyst is accommodated, and a support structure 3 for supporting catalyst. The catalytic reformer utilizes a process for converting hydrocarbon feedstock such as renewable carbonaceous materials like biomass into synthesis gas composed primarily of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2). It may be configured as fluidized-bed, fixed-bed, or entrained-flow systems. Among these, downward-flow configurations, in which hydrocarbon feedstock and reforming agents such as steam and oxygen descend through the reactor under gravity. The feedstock is provided to the catalytic reformer 1 from a feedstock inlet 11 at the topof the reactor shell 2 and product gas flows out from product gas outlet 12 at bottom part of the catalytic reformer 1.

[0025] Figure 2A and 2B depicts schematically two cross sections of the same catalytic reformer 1 , view only rotated 90 degrees around a center axis CL. The catalytic reformer 1 converts hydrocarbon feedstock into product gas, the catalytic reformer comprises a reactor shell 2 forming an enclosure and defining an interior space where catalyst is to be accommodated on the support structure and a feeding device 4 is provided to feed oxygen steam on to the catalyst when in use. The embodiment illustrated in FIG 2A and 2B is a three-stage catalytic reformer 1 that comprises three similar stages of support structure 3 for supporting catalyst (In FIG 2A and 2B the reference numbers are used only for one stage to keep the figures legible). The support structure 3 comprises - a grid 31 that allows hydrocarbon feedstock to flow through,- a cooling fluid circulation 33 within the grid 31 to provide a cooling membrane panel 34, wherein the grid 31 comprises an arrangement of tubes 35. The flow direction of the cooling fluid circulation 33 in successive support structures 3 is arranged to be reverse to the flow direction of the hydrocarbon feedstock. The support structure 3 is attached to the reactor shell 2 by means of welding and the support structure 3 extending outside the reactor shell 2 is enclosed in a heat insulation 21. Also, the heat insulation 21 encloses a continuous volume around the reactor shell 2.

[0026] Figure 3 depicts schematically a side view of an embodiment of the feeding device 4 and the support structure 3 similar to the embodiment shown in FIG. 2B. The support structure 3 comprises:- a grid 31 provided with a plurality of openings 32 (not shown in FIG. 3) that allows the hydrocarbon feedstock to flow through,- a cooling fluid circulation 33 within the grid 31 to provide a cooling membrane panel 34, the grid 31 comprises an arrangement of tubes 35 to provide the cooling fluid circulation 33, the tubes 35 being connected to each other by fins 36. The support structure 3 further comprises an inlet header 355 configured to receive cooling fluid and an outlet header 356 configured to discharge the cooling fluid, the inlet header 355 and the outlet header 356 are spaced apart in the flow direction F of the hydrocarbon feedstock.The arrangement of tubes 35 comprises a first group of tubes 351 , each of the tubes 35 of the first group of tubes 351 has a first end 353 and a second end 354, and extends throughout the interior space of the reactor shell 2 such that both the first end 353 and the second end 354 are located outside the reactor shell 2. The arrangement of tubes 35 further comprise a second group of tubes 352 in a stacked configuration along theflow direction F of the hydrocarbon feedstock. The stacked configuration may comprise one, two, three, four or more tubes 35 coupled to the tube 35 of the first group of tubes 351 , here an embodiment of two second group of tubes 352 are coupled to the first group of tubes 351. The flow direction CF of the cooling fluid circulation 33 has been arranged from bottom to top in a vertically advancing manner, so that the inlet header 355 is at a lower elevation than the outlet header 356 for the support structure 3.

[0027] Figure 4 depicts schematically an isometric cross section of a subsequence of the catalytic reformer 1 presented in Figure 1 and Figures 2A, 2B and 3. The feeding device 4 comprising headers 41 and tubes 42 is provided for feeding oxygen steam on the catalyst accommodated on the support structure 3. Also, here two second group of tubes 352 are coupled to the first group of tubes 351. The catalyst on bed is supported by the support structure 3 or grid 31 located at its base. This support structure 3 must be capable of withstanding the mechanical and thermal conditions present during operation of the reactor i.e. the catalyst reformer. In particular, the support structure is exposed to the high temperature’s characteristic of a reaction zone. For example, in processes such as the catalytic partial oxidation of methane or autothermal cracking of hydrocarbons, the temperature at the front face of the catalyst bed may reach or exceed 900 °C. Accordingly, the support structure 3 must be constructed of materials that maintain structural integrity at elevated temperatures, typically in the range of 600 °C to 1000 °C, and must be resistant to thermal degradation, sintering, or deformation. In addition to high temperature stability, the support must accommodate thermal cycling. During start-up and shutdown of the reactor, the catalyst holder and its components are subjected to rapid temperature changes. The support must therefore withstand differential thermal expansion and contraction without cracking or mechanical failure. Mechanically, the support must sustain the weight of the catalyst bed under both hot and cold conditions. The catalyst bed may comprise a monolithic structure, a ceramic foam, or a packed bed of catalyst particles, and the support must provide sufficient mechanical strength and rigidity to maintain the position of the bed without sagging, deflection, or collapse. The reactor shell 2 is provided with hatches 23 to enable operable access to inside of the reactor shell 2. Also, the support structure 3 extending outside the reactor shell 2 enclosed in the heat insulation 21 may be provided with an air-cooling system 22.

[0028] Figure 5A and 5B depicts schematically two layers of support structures 3 passing through the reactor shell 2 viewed from the top. In FIG 5A a grid 31 provided with a plurality of openings 32 that allows the hydrocarbon feedstock to flow through. The openings 32 are provided with perforated cover plates 321 to prevent catalyst to fall downthrough the openings, the cover plates 321 are perforated to prevent particle size of about 10 - 35 mm to penetrate the openings 32. The grid may be covered with a refractory lining to prevent wear and to control heat transfer. In FIG 5B it is depicted another layer below the layer of FIG. 5A. Here the grid 31, in the width direction, there is an embodiment where every third tube 35 arranged as the stacked configuration. Thus, it comprises a second group of tubes 352 in a stacked configuration along the flow direction of the hydrocarbon feedstock. On the right end of the FIG. 5B it is shown all the tubes 35, but in the middle, there are only stacked second group of tubes 352 illustrated.

[0029] Figure 6 depicts schematically an isometric cross section of a subsequence of the support structure 3 attached to the reactor shell 2. In this FIG 6 the first group of tubes 351 are configured in a plane transverse to a flow direction F of the hydrocarbon feedstock, and the plurality of openings 32 are formed on the fins 36 that connect the first group of tubes 351. The arrangement of tubes 35 further comprise a second group of tubes 352 in a stacked configuration along the flow direction of the hydrocarbon feedstock. The stacked configuration may comprise one, two (as presented in FIG 6), three, four or more tubes 35 coupled to the tube 35 of the first group of tubes 351 or connected to a fin 36 between the tubes 35 of the first group of tubes 351. T ubes 35 are connected to each other with fins 36 or other plate-like construction that determines the spacing between tubes 35.

[0030] Figure 7 depicts schematically a top view of a grid 31 provided with a plurality of openings 32 that allows the hydrocarbon feedstock to flow through. Furthermore, the support structure must permit uniform gas flow through the catalyst bed. It should be designed to minimize pressure drop while ensuring that the gaseous reactants pass through the entire active volume of the catalyst. The geometry and porosity of the support may be selected to avoid flow maldistribution, bypassing, or undesirable channelling. The openings 32 are provided with perforated cover plates 321 to prevent catalyst to fall down through the openings, the cover plates 321 are perforated to prevent particle size of about 10 - 35 mm to penetrate the openings 32.

[0031] The support structure 3 material must also be chemically compatible with the reactant and product gases, which may include hydrocarbons, oxygen, hydrogen, carbon oxides, water vapour, and possibly steam or inert gases. It should resist corrosion, oxidation, and carburization under reaction conditions. Preferred materials for the support include high-temperature resistant metallic alloys, such as Inconel®, Incoloy®, or Paralloy®, or refractory ceramics such as a-alumina, cordierite, or stabilized zirconia.

[0032] In some embodiments, the support structure may additionally function as part of the gas-tight containment system within the catalyst holder, preventing the bypass of reactants around the catalyst bed and contributing to the integrity of the flow path.

[0033] In the above description of drawings, the terms “upper”, “lower”, “on top”, “below”, “upward”, and “downward” relate to the above-mentioned, intended positions in the position shown in the figures. In this description, the singular form “a”, “an”, and “the” referring to a device or component does not exclude additional or a plurality of corresponding devices or components, unless where specifically specified. In the description, various devices and components may be described as “comprising” other components. The terms “comprise(s)”, “comprising”, “include(s)”, “having”, “has”, and variants thereof, are intended to be open- ended phrases that do not exclude the possibility of additional components, unless where specifically specified.

[0034] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred embodiments, it is obvious to the skilled person that, along with the technical progress, the basic idea of the invention can be implemented in many ways. The invention and its embodiments are thus not limited to the examples and samples described above but they may vary within the contents of patent claims and their legal equivalents. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.Reference number list1 catalytic reformer11 feedstock inlet12 product gas outlet 2 reactor shell20 shell wall21 insulation22 air cooling system 23 hatch3 support structure31 grid32 opening321 cover plate33 cooling fluid circulation 34 membrane panel 35 tube351 first group of tubes 352 second group of tubes 353 first end354 second end355 inlet header356 outlet header36 fin4 feeding device41 header42 tubeF flow directionCF cooling flowCL center axis

Claims

Claims1. A support structure (3) for supporting catalyst within a reactor, the support structure (3) comprises- a grid (31) provided with a plurality of openings (32) that allows hydrocarbon feedstock to flow through,- a cooling fluid circulation (33) within the grid (31) to provide a cooling membrane panel (34),characterized in that the grid (31) comprises an arrangement of tubes (35) to provide the cooling fluid circulation (33), the tubes (35) being connected to each other by fins (36).

2. A support structure (3) according to claim 1 , characterized in that the arrangement of tubes (35) comprises a first group of tubes (351), each of the tubes (35) of the first group of tubes (351) has a first end (353) and a second end (354), and is dimensioned to be extend throughout an interior space of a reactor shell (2) such that both the first end (353) and the second end (354) are located outside the reactor shell (2).

3. A support structure (3) according to any of the preceding claims, characterized in that the first group of tubes (351) are configured in a plane transverse to a flow direction (F) of the hydrocarbon feedstock, and the plurality of openings (32) are formed on the fins (36) that connect the first group of tubes (351).

4. A support structure (3) according to any of the preceding claims, characterized in that the arrangement of tubes (35) further comprises a second group of tubes (352) in a stacked configuration along the flow direction (F) of the hydrocarbon feedstock.

5. A support structure (3) according to any of the preceding claims, characterized in that the stacked configuration comprises one, two, three, four or more tubes (35) coupled to the tube (35) of the first group of tubes (351) or connected to the fin (36) that connects two first group of tubes (351).

6. A support structure (3) according to any of the preceding claims, characterized in that the grid (31), in the width direction, there is every second, third or fourth tube (35) arranged as the stacked configuration.

7. A support structure (3) according to any of the preceding claims, characterized in that tubes (35) are connected to each other with fins (36) or other plate-like construction that determines the spacing between tubes (35).

8. A support structure (3) according to any of the preceding claims, characterized in that the openings (32) are provided with perforated cover plates (321) to prevent catalyst to fall down through the openings, the cover plates (321) are perforated to prevent particle size of about 10 - 35 mm to penetrate the openings (32).

9. A support structure (3) according to any of the preceding claims, characterized in that the support structure (3) further comprises an inlet header (355) configured to receive cooling fluid and an outlet header (356) configured to discharge the cooling fluid, the inlet header (355) and the outlet header (356) are spaced apart in the flow direction (F) of the hydrocarbon feedstock.

10. A catalytic reformer (1) to convert hydrocarbon feedstock into product gas, the catalytic reformer comprising a reactor shell (2) forming an enclosure and defining an interior space where catalyst is accommodated, and a support structure (3) according to any of the preceding claims.

11. A catalytic reformer (1) according to claim 10, characterized in that the catalytic reformer (1) comprises a number of support structures (3), the number being at least one, but preferably two, three or more support structures (3) successively in the flow direction (F) of the hydrocarbon feedstock.

12. A catalytic reformer (1) according to any of the preceding claims, characterized in that the flow direction of the cooling fluid circulation (33) in successive support structures (3) is arranged to be reverse to the flow direction (F) of the hydrocarbon feedstock.

13. A catalytic reformer (1) according to any of the preceding claims, characterized in that the flow direction of the cooling fluid circulation (33) has been arranged from bottom to top in a vertically advancing manner, so that the inlet header (355) is at a lower elevation than the outlet header (356) for the support structure 3.

14. A catalytic reformer (1) according to any of the preceding claims, characterized in that the flow direction of the cooling fluid circulation (33) in successive support structures (3) has been arranged from bottom to top in a vertically advancing natural circulation manner, so that the inlet header (355) is at a lower elevation than the outlet header (356) for the support structure (3).

15. A catalytic reformer (1) according to any of the preceding claims, characterized in that the support structure (3) is attached to the reactor shell (2) by means of welding.

16. A catalytic reformer (1) according to any of the preceding claims, characterized in that the heat insulation (21) encloses a continuous volume around the reactor shell (2).

17. A catalytic reformer (1) according to any of the preceding claims, characterized in that the support structure (3) extending outside the reactor shell (2) is enclosed in a heat insulation (21).

18. A catalytic reformer (1) according to any of the preceding claims, characterized in that the support structure (3) extending outside the reactor shell (2) enclosed in the heat insulation (21) is provided with an air-cooling system (22).

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