Fixed-bed tubular reactor with multi-part insert

Abstract

The invention relates to a tubular reactor (1) comprising a catalytic powder bed confined in an annular space (30), a hollow insert (20) comprising a distribution chamber (40) and a collection chamber (50), a second wall (21) comprising at least one distribution opening (42) and at least one collection opening, characterized in that the hollow insert (20) comprises an insert body obtained by assembling a plurality of separate intermediate insert parts, each intermediate insert part having a shape, when viewed in cross-section relative to the longitudinal axis (XX'), defined by a first segment, a second segment and a peripheral portion connecting the first and second segments, defining therebetween an internal angle strictly between 0° and 360°.

Description

[0001] DESCRIPTION

[0002] TITLE: Fixed-bed tubular reactor with multi-part insert

[0003] TECHNICAL FIELD OF THE INVENTION

[0004]

[0001] The present invention relates to the general field of heat exchanger reactors. In particular, the present invention relates to the field of catalytic heat exchanger reactors using a solid catalyst, and especially a solid catalyst in powder form.

[0005]

[0002] More specifically, the invention relates to a catalytic reactor-exchanger capable of implementing exothermic organic synthesis processes. These organic compounds may notably include synthetic fuels and propellant.

[0006] STATE OF THE ART

[0007]

[0003] Catalytic reactors using solid catalysts are widely used for the synthesis of organic compounds such as synthetic fuels or fuels, including natural gas substitutes, dimethyl ether or methanol.

[0008]

[0004] These compounds are obtained in particular by reaction of hydrogen and carbon oxide in the presence of a suitable solid catalyst.

[0009]

[0005] However, the chemical reactions involved in the synthesis of these compounds are highly exothermic and consequently release a quantity of heat that can degrade the solid catalyst. This degradation results in a reduction in the conversion rate of the chemical species present and a decrease in the selectivity of the reactions involved. In other words, the solid catalyst is deactivated by the heat.

[0010]

[0006] Thus, in practice, these reactions can be implemented in a shell-and-tube reactor-exchanger comprising a reactive channel equipped with the solid catalyst and continuously cooled by a heat transfer fluid. In this type of reactor, the reactive gases flow axially through tubes containing a catalyst, for example, in powder form.

[0007] However, despite the implementation of cooling by the heat transfer fluid, this type of reactor remains sensitive to the heat released by the reactions occurring within it.

[0011]

[0008] In particular, a hot spot, generally observed near the reactive gas inlet, degrades the solid catalyst and therefore reduces the performance of the reactor-exchanger.

[0009] In order to limit these effects, the following solutions have been proposed:

[0012] - a reduction in the volume density of the catalyst, in particular by depositing the latter on the walls of the tube or of an insert or by diluting it in a non-reactive medium;

[0013] - a dilution of the reactive gases with a portion of the products generated to decrease the activity of the reaction;

[0014] - perform several injection points of one or more reagents to distribute the hot spot area over a larger surface;

[0015] - a reduction in the dimensions of the tubes or by placing heat-conducting parts on them in order to improve the cooling of the tubes.

[0016]

[0010] These solutions are not satisfactory, however. Indeed, even though they reduce the effects of the hot spot, they are complex to implement.

[0017]

[0011] Moreover, their implementation reduces the flexibility of use of the reactor-exchanger, and makes the latter not very compact.

[0018]

[0012] To overcome these problems, an arrangement was proposed that distributes the reactants along the entire length of the tubes. This solution allows for better temperature homogeneity along the entire length of the reactor.

[0019]

[0013] In this regard, US patents 3,758,279 A, ​​4,374,094 A, EP 0 560 157 A1, and 2,997,374 A propose reactor-exchangers implementing reactant distribution from an annular distribution space. Specifically, these reactor-exchangers, generally cylindrical in shape, comprise, arranged coaxially from outside the reactor, a tube, the annular distribution space, a catalyst charge, and a collection space.

[0020]

[0014] This arrangement is not satisfactory, however. Indeed, the presence of the annular distribution space around the catalyst charge limits heat transfer from the catalyst to the tube, rendering the cooling systems generally used ineffective. It remains possible, however, to insert heat-conducting elements into the reactor. Such a solution, however, remains incompatible with reactors containing small-diameter tubes.

[0021]

[0015] Conversely, document CN 103990420 A proposes implementing an insert with a distribution chamber and a collection chamber, arranged in the center of a tube and defining with the latter an annular space housing the solid catalyst.

[0016] However, the arrangement proposed in this document does not allow for homogeneous distribution within the annular space. More specifically, this arrangement does not allow for obtaining an optimal temperature profile within the solid catalyst.

[0022]

[0017] Furthermore, a principle for the staged distribution of gas in a reactor-exchanger is known from the Applicant's European patent application EP 3 827 895 A1. The reactor comprises a catalyst located in an annular space between a hollow tube and a hollow insert equipped with distribution and collection chambers. The hollow insert typically corresponds to a single-piece component produced by specific manufacturing techniques that limit the possibilities in terms of materials, geometry, manufacturing time, and excess material used, among other things.

[0023]

[0018] An object of the present invention is to propose a fixed-bed tubular reactor allowing a more uniform distribution of reactants within the solid catalyst.

[0024]

[0019] Another object of the present invention is also to propose a fixed-bed tubular reactor allowing a more homogeneous distribution of the heat flux generated within the solid catalyst.

[0025]

[0020] Another objective of the present invention is also to propose a tubular reactor allowing better cooling management.

[0026]

[0021] Another object of the present invention is also to propose a tubular reactor for which the reliability and lifespan are improved compared to known reactors in the prior art.

[0027]

[0022] Another object of the present invention is to propose a tubular reactor making it possible to optimize (increase) the time of passage of the gases in the fixed bed of catalytic powder.

[0028]

[0023] Another object of the present invention is to propose a tubular reactor comprising an insert of improved design, in particular through specific manufacturing techniques.

[0029] DESCRIPTION OF THE INVENTION

[0030]

[0024] The invention aims to remedy at least partially the needs mentioned above and the disadvantages relating to the achievements of the prior art.

[0031]

[0025] The invention thus relates, according to one of its aspects, to a fixed-bed tubular reactor extending, along a longitudinal axis, between a first end and a second end, said reactor comprising a bed of catalytic powder confined in an annular space delimited by a first wall of a hollow tube and a second wall of a hollow insert, disposed in the hollow tube and coaxially therewith, the hollow insert comprising at least one distribution chamber and at least one collection chamber, separated from each other by a separating wall, and comprising, respectively, a gas inlet opening and a gas outlet opening, the second wall comprising at least one distribution opening and at least one collection opening, which extend over a length, the distribution opening allowing the distribution of a gas capable of being admitted through the inlet opening of the distribution chamber to the annular space,and the collecting opening allowing the collection of the gas distributed in the annular space by the collecting chamber, characterized in that the hollow insert comprises an insert body obtained by the assembly of a plurality of distinct intermediate insert pieces, each intermediate insert piece having, by observation in cross-section with respect to the longitudinal axis, a shape defined by a first segment, a second segment and a peripheral portion connecting the first and second segments, which define between them an internal angle strictly between 0° and 360°.

[0032]

[0026] The reactor according to the invention may further comprise one or more of the following characteristics taken individually or in any possible technical combinations.

[0033]

[0027] The gas inlet opening may be located at the first end. The gas outlet opening may be located at the second end. Alternatively, the gas inlet opening and the gas outlet opening may be located at the same end, in particular at the first end.

[0034]

[0028] The first segment and the second segment may have the same dimension, in particular the same length.

[0035]

[0029] The peripheral portion can have all types of shape, including rectilinear, curved or open polygonal, and preferably be in the shape of a circular arc.

[0036]

[0030] The hollow tube and (hollow insert) advantageously have a substantially cylindrical shape, but not necessarily a cylindrical shape of revolution.

[0037]

[0031] Furthermore, since the hollow insert is placed in the hollow tube and coaxially with it, the annular space can exhibit rotational symmetry.

[0032] Thus, the reactor according to the present invention allows the reactive gases to be distributed relatively homogeneously throughout the annular space, due to the extent of the distribution opening. These gases then react with the catalytic powder bed over the entire cross-section covered by the distribution opening. The products of the gas reaction, as well as the unreacted gases, are collected at the collection opening and discharged from the reactor through the discharge opening opposite the inlet opening.

[0038]

[0033] This arrangement, in which the gases are admitted through one end and expelled through the other end, allows for a better distribution of the reactive species (the gases) in the annular space, and consequently a better distribution of the heat that may be released during the reaction of the reactive species in the annular space.

[0039]

[0034] This better distribution of the heat released makes it possible to consider a less powerful cooling system and therefore smaller in size.

[0040]

[0035] The arrangement according to the present invention therefore makes it possible to consider a more compact reactor, and one with improved reliability compared to the tubular reactors known in the prior art.

[0041]

[0036] Advantageously, each intermediate insert piece can have, by observation in cross-section with respect to the longitudinal axis, a fraction of a circle shape defined by a peripheral portion in the form of an arc of a circle connecting the first segment in the form of a first radius and the second segment in the form of a second radius.

[0042]

[0037] The junction between the first segment and the second segment can be curved and can have an internal radius of curvature, the internal angle being in particular different from 180°.

[0043]

[0038] In addition, the junction between the first segment and the peripheral portion and / or the junction between the second segment and the peripheral portion may be curved and may have an external radius of curvature.

[0044]

[0039] The number of intermediate insert pieces may be greater than or equal to 2, in particular greater than or equal to 4, in particular less than or equal to 6.

[0045]

[0040] Advantageously, the plurality of intermediate insert pieces may comprise four intermediate insert pieces, each intermediate insert piece having in particular, by observation in cross-section with respect to the longitudinal axis, a quarter-round shape, the internal angle being in particular substantially equal to 90°.

[0046]

[0041] Furthermore, the plurality of intermediate insert pieces may comprise at least two axially offset intermediate insert pieces such that there is at least one cross-section with respect to the longitudinal axis, located in a non-reactive zone of the tubular reactor, in which only a portion of said at least two intermediate insert pieces can be observed.

[0042] Moreover, there may be at least one cross-section with respect to the longitudinal axis, located in a reactive zone of the tubular reactor, in which all the intermediate insert pieces can be observed.

[0047]

[0043] In addition, two adjacent intermediate insert pieces can be fixed together, in particular by welding and / or brazing, in particular at a meeting area, forming a longitudinal groove, connecting the junction between the peripheral portion and the first or second segment of a first intermediate insert piece and the junction between the peripheral portion and the first or second segment of a second intermediate insert piece, adjacent to the first intermediate insert piece.

[0048]

[0044] The hollow insert may further include centering means maintaining the hollow insert in a substantially coaxial position with the hollow tube, the centering means being in particular in the form of centering pins disposed at the level of a meeting zone, forming a longitudinal groove, connecting the junction between the peripheral portion and the first or second segment of a first intermediate insert piece and the junction between the peripheral portion and the first or second segment of a second intermediate insert piece, adjacent to the first intermediate insert piece.

[0049]

[0045] The centering means can be fixed to the insert body, in particular by welding and / or brazing.

[0050]

[0046] Each intermediate insert piece can be obtained by means of a drawing process. Each intermediate insert piece can also be obtained by means of a rolling and welding process.

[0051]

[0047] Furthermore, the assembly of the intermediate insert parts can be achieved by fitting, welding, brazing and / or joining intermediate insert parts in the form of collars with a substantially circular cross-section.

[0052]

[0048] In addition, the insert body can be made of iron, nickel, iron alloy and / or nickel alloy, among others.

[0053]

[0049] In addition, the external diameter of the insert body may be less than 5 cm, in particular less than 3 cm.

[0054]

[0050] At least one distribution chamber can be sealed at the second end, and at least one collection chamber can be sealed at the first end.

[0055]

[0051] The reactor may include, at the first end and at the second end, respectively, a distribution space and a collection space between which the insert is disposed.

[0052] The catalytic powder may be retained in the annular space by a fibrous seal at each end of the annular space.

[0056]

[0053] The fibrous material seal can be held in compression against the catalytic powder by a spring, the spring being against a retaining plate mechanically linked to the tube.

[0057]

[0054] The fibrous material seal in combination with the spring(s) can allow for better compaction of the catalytic powder and prevent attrition of the latter during handling or transport of the reactor.

[0058]

[0055] The outer wall may be without an opening on a first section and a second section extending from, respectively, the first end and the second end, the first section and the second section being in overlap with the powder bed over a height H, the height H being between 0.5 times and 10 times, advantageously between 1 time and 2 times, the distance separating a distributing opening from an immediately adjacent collecting opening, and measured along the outer surface of the outer wall.

[0059]

[0056] Thus, such an arrangement can make it possible to impose a passage time on reactive gases likely to penetrate the annular space through the fibrous joint.

[0060]

[0057] The hollow insert can be provided with centering means maintaining the latter in a substantially coaxial position with the hollow tube; advantageously, the centering means can include bosses formed on the second wall.

[0061]

[0058] These centering means can allow for easier assembly of the reactor.

[0062]

[0059] The surface area of ​​a section of the distribution chamber along a cross-sectional plane to the longitudinal axis can decrease from the first end to the second end; advantageously, said surface area can be zero at the second end.

[0063]

[0060] The surface area of ​​a section of the collection chamber along a cross-section plane to the longitudinal axis can increase from the first end to the second end; advantageously, said surface area can be zero at the first end.

[0064]

[0061] The collecting opening and the distributing opening may have a width between 1 / 400 and 1 / 2, advantageously between 1 / 20 and 1 / 100, of the diameter of the hollow tube.

[0065]

[0062] The collecting opening and the distributing opening may each include a filter preventing the passage of catalytic powder into either of the collecting or distributing chambers. The filter may include a plurality of inclined fiber planes.

[0063] Furthermore, the invention also relates, according to another aspect, to a method for manufacturing an insert body of a hollow insert of a tubular reactor as defined above, in which the plurality of intermediate insert pieces is obtained by a drawing and / or rolling and welding process.

[0066]

[0064] The assembly of the intermediate insert parts can be obtained by fitting, welding, brazing and / or joining intermediate insert parts in the form of collars of substantially circular section.

[0067] BRIEF DESCRIPTION OF THE FIGURES

[0068]

[0065] Other advantages, objectives and particular features of the invention will become apparent from the following non-limiting description of at least one embodiment of the present invention, with reference to the accompanying figures, in which: Figure 1 is a schematic representation of a fixed-bed tubular reactor, along a longitudinal section plane passing through a longitudinal axis of the reactor; Figure 2 is a schematic representation of the reactor of Figure 1 along a transverse section plane perpendicular to the longitudinal axis; Figure 3 is a representation of a filter, and in particular of a filter formed of four fiber layers, capable of being implemented in the tubular reactor of Figure 1; Figure 4 is a representation of a fixed-bed tubular reactor such as that of Figure 1 at the first end illustrating the arrangement of the seal and the spring retaining the catalytic powder bed.Figure 5 is a schematic representation of the hollow insert along section plane AA' of Figure 4; Figure 6 is a schematic representation of an alternative embodiment of a fixed-bed tubular reactor along a longitudinal section plane passing through a longitudinal axis of the reactor; Figures 7A, 7B, 7C, 7D and 7E are views, respectively, along section planes A, B, C, D and E of the hollow insert shown in Figure 6; Figure 8 is a schematic representation of another alternative embodiment of a fixed-bed tubular reactor along a longitudinal section plane passing through a longitudinal axis of the reactor; Figures 9 and 10 are views, respectively, along section planes CC' and DD' of the hollow insert shown in Figure 8; Figure 11 is a schematic representation, along a cross-section with respect to the longitudinal axis, of an insert body of a tubular reactor according to the invention.Figure 12 is a schematic representation, in cross-section with respect to the longitudinal axis, of a hollow insert comprising the insert body of Figure 11 and centering means, and Figure 13 is a schematic representation, in perspective view, of a particular embodiment of a hollow insert of a tubular reactor according to the invention.

[0069]

[0066] Throughout these figures, identical references may designate identical or analogous elements.

[0070]

[0067] Furthermore, the different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more legible.

[0071] DETAILED DESCRIPTION OF THE INVENTION

[0072]

[0068] The present invention relates to a tubular reactor-exchanger with a fixed catalytic powder bed. In particular, the catalytic powder bed is confined in an annular space delimited by a first wall of a hollow tube and a second wall of a hollow insert disposed in said tube and coaxially therewith.

[0073]

[0069] The hollow insert is arranged in particular to allow the admission of reactive gases through a first end of the reactor into a distribution chamber of the insert. These gases are then distributed over a section of the annular space extending over a length L, parallel to a longitudinal axis XX' of the reactor, through a distribution opening allowing the passage of gases from the distribution chamber to said annular space.

[0074]

[0070] The products resulting from the reaction between reactive species are then collected, via a collection opening, into a collection chamber of the hollow insert, isolated from the distribution chamber by a separating wall.

[0075]

[0071] The evacuation of the products is carried out through an evacuation opening of the collection chamber at the level of the second end.

[0076]

[0072] Figures 1 and 2 show an example of the realization of a fixed-bed tubular reactor.

[0077]

[0073] The tubular reactor 1 comprises a hollow tube 10 which extends along a longitudinal axis XX', between a first end 11 and a second end 12.

[0078]

[0074] The hollow tube 10 may have rotational symmetry about the longitudinal axis XX'. The hollow tube 10 may comprise a metal, and in particular a metal selected from: steel, aluminum alloy, copper, nickel, among others. The diameter of the internal surface of the hollow tube 10 may be between 5 mm and 100 mm.

[0079]

[0075] The wall, referred to as the first wall, forming the hollow tube 10 can have a thickness of between 0.5 mm and 10 mm. The hollow tube 10 can have a length of between 10 times and 200 times its internal diameter.

[0080]

[0076] The tubular reactor 1 also includes a hollow insert 20 which also extends along the longitudinal axis XX' and has an external shape substantially cylindrical.

[0081]

[0077] The hollow insert 20 is housed in volume V of the hollow tube 10 coaxially with the latter. In particular, the insert 20 comprises a wall, referred to as the second wall 21, which, together with the first wall of the hollow tube, delimits an annular space 30.

[0082]

[0078] The annular space 30 is, in this respect, filled with a catalytic powder which will be the site of the conversion reactions of reactive gases likely to pass through the tubular reactor 1.

[0083]

[0079] The annular space 30 can have a thickness, defined as the distance between the first wall and the second wall, of between 2% and 20% of the internal diameter of the first wall.

[0084]

[0080] In a particularly advantageous manner, the hollow insert 20 can be provided with centering means maintaining the latter in a substantially coaxial position with the hollow tube 10. For example, as shown in Figure 6 relating to a second variant of the tubular reactor 1 discussed later in the statement, the centering means include bosses 22 formed on the second wall 21.

[0085]

[0081] These centering means 22 make it possible in particular to consider a hollow insert 20 with a length at least 20 times greater than the diameter of the insert 20. Furthermore, these centering means 22 also make it easier to assemble the tubular reactor 1.

[0086]

[0082] The hollow insert 20 further comprises at least one distribution chamber 40 and at least one collection chamber 50. In particular, the hollow insert 20 may comprise between one and four distribution chambers 40 and between one and four collection chambers 50.

[0087]

[0083] The distribution chambers 40 and the collection chambers 50 are advantageously arranged alternately, extend over the entire length of the hollow insert 20 and are separated from each other by separating walls 60.

[0088]

[0084] More particularly, the separating walls 60 extend along the entire length of the hollow insert 20 in the volume defined by the hollow insert 20.

[0085] Furthermore, at least one distribution chamber 40 includes an inlet opening 41 at one end of the insert 20 through which one or more reactive gases are likely to be admitted.

[0089]

[0086] Equivalently, at least one collection chamber 50 includes an evacuation opening 51 at the other end of the hollow insert 20 and through which one or more gases are likely to be evacuated.

[0090]

[0087] The hollow insert 20 is also provided with at least one distributing opening 42, or distribution opening, and at least one collecting opening 52, or collection opening. In particular, the distributing opening 42 forms a passage permeable to reactive gases from the distributing chamber 40 to the annular space 30. Equivalently, the collecting opening 52 forms a passage permeable to gases from the annular space 30 to the collecting chamber 50. The distributing opening 42 and collecting opening 52 extend over a length L.

[0091]

[0088] Advantageously, the length L is greater than half, advantageously three-quarters of the extension length along the longitudinal axis XX' of the annular space 30.

[0092]

[0089] Furthermore, at least one distribution chamber 40 is closed at the second end 12, while at least one collection chamber 50 is closed at the first end 11. In this respect, as illustrated in Figure 1, the distribution chamber 40 is closed by a distribution wall 43, while the collection chamber 50 is closed by a collection wall 53.

[0093]

[0090] Complementarily, the tubular reactor 1 may include at the first end 11 and at the second end 12, respectively, a distributor space 13 and a collector space 14 between which the hollow insert 20 is disposed.

[0094]

[0091] Advantageously, the collection opening 52 and the distribution opening 42 have a width between 1 / 400 and 1 / 2, advantageously between 1 / 20 and 1 / 100, of the diameter of the hollow tube 10.

[0095]

[0092] Advantageously, the collection opening 52 and the distribution opening 42 each include a filter 61 preventing the passage of catalytic powder into either of the collection chambers 50 or distribution chambers 40. Specifically, the filter(s) 61 make it possible to confine the catalyst in the annular space 30 due to their impermeability to the catalyst.

[0096]

[0093] For example, and as illustrated in Figure 3, the filter 61 may comprise a plurality of planes 61a, 61b, 61c, and 61d comprising fibers. The example illustrated in Figure 3 specifically comprises four planes, each provided with rectangular or round fibers inclined at plus or minus 45° to the longitudinal axis XX'. More particularly, the fibers of two successive planes are oriented at two different angles, and are notably perpendicular from one plane to the other.

[0097]

[0094] During the operation of reactor 1, one or more reactive gases are admitted into the distribution chamber 40 through the inlet opening 41. These gases then pass through the distribution opening 42 and flow into the annular space 30 to come into contact with the catalytic powder bed. During this flow into the annular space 30, which occurs essentially between a distribution opening 42 and an immediately adjacent collection opening 52, the reactive gases are converted, at least partially, into products. These products, along with the unreacted fraction of reactive gases, pass through the aforementioned collection opening 52 and are collected in the collection chamber 50. The collected products and unreacted reactive gases are then discharged through the discharge opening 51.

[0098]

[0095] Thus, the extent of the distribution openings 42 along the length L allows the reactive gases to be distributed in the annular space 30 along said length L. In other words, this arrangement allows the amount of heat likely to be produced during the conversion of the reactive gases into products to be distributed over the entire length L. This arrangement thus limits the local temperature increase of the catalytic powder bed. The extent of the collection openings 52 along the length L allows, according to an equivalent principle, the heating of the catalytic powder bed.

[0099]

[0096] Furthermore, the arrangement of the inlet openings 41 and outlet openings 51 on opposite ends of the hollow insert 20 also contributes to a better distribution of the reactants within the annular space 30 and consequently to a better homogenization of the temperature of the catalytic powder bed.

[0100]

[0097] All these aspects contribute to limiting the occurrence of hot spots and thus preserving the catalytic powder bed. This results in improved reliability of the tubular reactor 1 and an increase in its service life.

[0101]

[0098] According to a particularly advantageous aspect illustrated in figure 4, the catalytic powder is retained in the annular space 30 by a fibrous material seal 31 at each end of the annular space 30.

[0102]

[0099] Insofar as the seal is made of fibrous material, it is necessarily porous and therefore permeable to reactive gases. The fibrous material may in this respect comprise at least one of the following elements selected from: glass fibers, ceramic fibers, metal fibers, carbon fibers, polymer fibers, among others.

[0103]

[0100] The seal 31 may, in particular, be in the form of a braid, a sheath, a cord, or simply consist of a filling of fibrous material. The fibrous material is advantageously a thermal insulator and has a thermal conductivity substantially equivalent to that of the catalyst used (0.2 W / m / K to 10 W / m / K).

[0104]

[0101] According to an advantageous embodiment, the fibrous material seal 31 is held in compression against the catalytic powder by a spring 32. For example, the spring 32 is abutted against a retaining plate 33 mechanically linked to the tube by a ring 34.

[0105]

[0102] The fibrous material seal 31 in combination with the spring(s) allows for better compaction of the catalytic powder and prevents attrition of the latter during handling or transport of the reactor.

[0106]

[0103] Insofar as the seal 31 is porous, reactive gases can penetrate the annular space directly without passing through the distribution chamber 40.

[0107]

[0104] In this case (Figure 4), it is particularly advantageous to provide an arrangement of the hollow insert 20 that allows the reactive gas to follow a predetermined path within the annular space 30 in order to promote its conversion upon contact with the catalytic powder bed. This predetermined path length is between 2 and 100 times, advantageously between 3 and 10 times, the distance D1 (Figure 5) separating a distribution opening 42 from an immediately adjacent collection opening 52, and measured along the external surface of the second wall 21 of the insert 20.

[0108]

[0105] To this end, the second wall 21 may be devoid of an opening onto a first section 21a and a second section which extend from, respectively, the first end 11 and the second end 12.

[0109]

[0106] In this respect, the first section 21a and the second section overlap with the powder bed over a height H1. The height H1 being between 0.5 times and 10 times, advantageously between one time and 2 times, the distance D1 separating a distribution opening 42 from an immediately adjacent collection opening 52, and measured along the external surface of the second wall 21.

[0110]

[0107] Figure 6 illustrates a second embodiment which essentially retains the characteristics of the first embodiment. The hollow insert 20 of this second embodiment is advantageously manufactured using an additive manufacturing technique.

[0111]

[0108] According to this second variant, the distribution chamber 40 has a convergent profile from the first end 11 to the second end 12.

[0112]

[0109] In other words, the surface area S40 of a section of the distribution chamber 40 along a cross-sectional plane to the longitudinal axis XX' decreases from the first end 11 to the second end 12 (Figures 7A to 7E), advantageously, said surface area is zero at the second end 12.

[0110] Equivalently, the surface area S50 of a section of the collection chamber 50 along a cross-sectional plane to the longitudinal axis XX' increases from the first end 11 to the second end 12, advantageously, said surface area is zero at the first end 11.

[0113]

[0111] This arrangement of the distribution chambers 40 and collection chambers 50 minimizes pressure losses related to gas circulation within them. Flow inhomogeneities in the annular space 30 are thus reduced.

[0114]

[0112] Figure 8 shows a hollow insert 20 that can be implemented according to a third embodiment. This third embodiment essentially retains the characteristics of the first and second embodiments.

[0115]

[0113] The insert 20 relating to this second variant can be manufactured by machining, cutting, electro-erosion, extrusion, among others.

[0116]

[0114] In particular, the insert 20 comprises according to this variant a main body 20a interposed between two terminal bodies 20b, 20c, and assembled by means of a joint 20d.

[0117]

[0115] The two terminal bodies 20b, 20c, illustrated in figure 8, comprise a cylindrical wall that is not permeable to gas, reproducing the first section 21a described in the first variant, and include distribution openings 42 (or collection openings 52).

[0118]

[0116] In the examples described above, the insert 20 is typically made in one piece. The manufacturing techniques envisaged, such as additive manufacturing, machining, cutting, electrical discharge machining or extrusion, allow the direct production of one-piece inserts.

[0119]

[0117] Advantageously, the invention proposes the production of a plurality of intermediate insert pieces which, joined together, form the insert body. The insert is then obtained with such an insert body and the other elements that compose it, such as centering means 22, filters 61, etc.

[0120]

[0118] The joining of the intermediate insert parts can, for example, consist of an assembly by interlocking, welding, brazing or even by joining collars whose section is substantially circular.

[0121]

[0119] The intermediate parts can be produced by means of an industrial tube drawing process through a die, or by means of a rolling and welding process of a metal strip, in particular a sheet metal strip, by successive passage through rollers.

[0122]

[0120] The production of an insert body by assembling several intermediate insert parts, obtained in particular by a drawing process and / or a rolling and welding process, has many advantages compared with the production of a one-piece insert body and the processes for obtaining such a one-piece insert.

[0123]

[0121] Thus, unlike extrusion, which only allows the use of aluminum alloys for complex geometries, it is possible here to produce an insert body from iron, nickel, iron alloy, and / or nickel alloy. This type of material may be necessary for the mechanical strength and chemical resistance of the insert under the intended operating conditions.

[0124]

[0122] Furthermore, unlike machining, electrical discharge machining (EDM), and additive manufacturing, manufacturing time can be reduced by using intermediate insert parts obtained by drawing and / or rolling and welding. It is also possible, unlike these manufacturing techniques, to produce part lengths exceeding 1 m with external diameters (De) of insert bodies less than 5 cm, or even less than 3 cm.

[0125]

[0123] In addition, unlike machining, electro-erosion and cutting, the amount of material lost is greatly reduced.

[0126]

[0124] We will now describe with reference to figures 11 to 13 the making of hollow inserts 20 for a tubular reactor 1 according to the invention, for example a tubular reactor 1 as described previously.

[0127]

[0125] Advantageously, the hollow insert 20 comprises an insert body 20i which is made in several parts, and is therefore not a single piece like prior art designs. This insert body 20i is obtained by assembling several separate intermediate insert parts 20ip. These intermediate insert parts 20ip are obtained, for example, by means of a drawing process, in particular drawing a tube through a die, and / or by means of a rolling and welding process, in particular rolling and welding a sheet metal strip by successive passage between rollers, as described above.

[0128]

[0126] The assembly of the intermediate parts of insert 20ip can be obtained by fitting, welding, brazing and / or joining intermediate parts of insert 20ip in the form of collars of substantially circular section.

[0129]

[0127] These intermediate insert parts 20ip can advantageously be made of iron, nickel, iron alloy and / or nickel alloy.

[0130]

[0128] In the example of Figures 11 and 12, which is not limiting of the invention, the hollow insert 20 comprises an insert body 20i obtained by assembling four intermediate insert pieces 20ip.

[0131]

[0129] Each intermediate insert piece 20ip, when viewed in cross-section with respect to the longitudinal axis XX', as shown in Figures 11 and 12, has a shape defined by a first segment R1, a second segment R2, and a peripheral portion C connecting the first segment R1 and the second segment R2. In this example, the first R1 and second R2 segments are first and second radii, and the peripheral portion C is in the form of a circular arc. However, these choices are not limiting; in particular, the peripheral portion could have another shape, for example, straight, curved, or polygonal.

[0132]

[0130] Thus, each intermediate insert piece 20ip, when viewed in cross-section, has a fractional-circle shape, here a quarter-circle shape, defined by a circular arc C connecting a first radius R1 and a second radius R2 of the same value, defining between them an internal angle α strictly between 0° and 360°, and here approximately equal to 90°. These intermediate insert pieces 20ip, by translating this fractional-circle shape along the longitudinal axis XX', take the form of hollow flutes. Their assembly allows for the formation of an insert body 20i with a substantially cylindrical shape.

[0133]

[0131] As can be seen in Figures 11 and 12, the junction between the first radius R1 and the second radius R2 is curved and has an internal radius of curvature, the internal angle a being substantially equal to 90°. At the meeting of the four corresponding junctions of the four intermediate pieces of insert 20ip, a free space E is formed of approximately square shape.

[0134]

[0132] In addition, the junction between the first radius R1 and the arc of circle C, and the junction between the second radius R2 and the arc of circle C, for each intermediate piece of insert 20ip, is curved and has an external radius of curvature.

[0135]

[0133] Thus, for two adjacent 20ip insert intermediate pieces, these curved junctions form a meeting zone S defined by a longitudinal groove at which the 20ip insert intermediate pieces are fixed together, in particular by a weld and / or brazing bead.

[0136]

[0134] Furthermore, as can be seen in Figure 12, the hollow insert 20 includes centering means 22, here in the form of cylindrical centering pins 22, which hold the hollow insert 20 in a substantially coaxial position with the hollow tube 10. These centering means 22 are arranged at the meeting areas S forming longitudinal grooves. They are fixed to the insert body 20i, for example by means of weld and / or brazing beads S1, on either side of each centering means 22.

[0137]

[0135] Each intermediate insert piece 20ip allows a distribution chamber 40 to be defined with an inlet opening 41 or a collection chamber 50 with an outlet opening 51, separated by separating walls 60, here in the form of the union of a first radius R1 of a first intermediate insert piece 20ip and a second radius R2 of a second intermediate insert piece 20ip, adjacent to the first insert piece 20ip.

[0138]

[0136] Moreover, this geometry makes it possible to obtain an external diameter De of the insert body 20i, visible in figure 11, which can be less than 5 cm, better less than 3 cm.

[0139]

[0137] Advantageously, this geometry makes it easier to set up the centering means 22 thanks to the formation of the longitudinal grooves of the meeting areas S.

[0140]

[0138] Furthermore, Figure 13 represents a hollow insert 20 in which an offset exists between the intermediate insert pieces 20ip.

[0141]

[0139] In particular, two opposing intermediate insert pieces 20ip are of the same axial length along the longitudinal axis XX' and are observed simultaneously in any cross-section passing through one of them. However, the two other opposing intermediate insert pieces 20ip, which are adjacent to them, are axially offset.

[0142]

[0140] Specifically, in the example of Figure 13, two adjacent 20ip insert intermediate pieces are axially offset so that there is at least one cross-section with respect to the longitudinal axis XX', located in a non-reactive zone ZNR of the tubular reactor 1, in which only one of the two adjacent 20ip insert intermediate pieces is observed.

[0143]

[0141] On the other hand, in a reactive zone ZR of the tubular reactor 1, all the intermediate insert pieces 20ip are observed in cross-section.

[0144]

[0142] This axial offset of the intermediate insert pieces 20ip is made possible by not designing a one-piece insert body 20i. However, since the hollow insert 20 generally has to have a non-reactive zone ZNR, or dead zone, at its ends, because it is difficult to thermalize these ends correctly, it is possible here to place only the intermediate insert pieces 20ip that are to receive the reagents R, on the one hand, and those that are to allow the products P to exit, on the other.

[0145]

[0143] Thus, the intermediate insert pieces 20ip, which serve to distribute the reagents R, do not extend into the non-reactive zone ZNR of the end dedicated to the outlet of the tubular reactor 1. Similarly, the intermediate insert pieces 20ip, which serve to collect the reaction products P, do not extend into the non-reactive zone ZNR of the end dedicated to the inlet of the reagents R into the tubular reactor 1. Advantageously, this makes it possible to reduce the amount of raw material used for an insert 20 by making the intermediate insert pieces 20ip shorter than the axial length of the finished insert 20.

[0144] It should be noted that the features stated above in connection with the first, second, and third embodiments, described with reference to Figures 1 to 10, are applicable to the present invention when technically compatible therewith.In particular, the inserts 20 described with reference to Figures 11 to 13 can be incorporated into the tubular reactors 1 described with reference to Figures 1 to 10. In addition, the inserts 20 described with reference to Figures 1 to 10 can be made in several parts as described with reference to Figures 11 to 13.

[0146]

[0145] The tubular reactor according to the present invention is advantageously implemented for the synthesis of methane, methanol, dimethyl ether or even to implement the Fisher-Tropsch synthesis.

[0147]

[0146] Of course, the invention is not limited to the embodiments just described. Various modifications can be made to them by a person skilled in the art.

Claims

DEMANDS 1. Tubular reactor (1) with a fixed bed extending, along a longitudinal axis (XX'), between a first end (11) and a second end (12), the reactor (1) comprising a bed of catalytic powder confined in an annular space (30) delimited by a first wall of a hollow tube (10) and a second wall (21) of a hollow insert (20), disposed in the hollow tube (10) and coaxially therewith, the hollow insert (20) comprising at least one distribution chamber (40) and at least one collection chamber (50), separated from each other by a separating wall (60), and comprising, respectively, a gas inlet opening (41) and a gas outlet opening (51), the second wall (21) comprising at least one distribution opening (42) and at least one collection opening (52), which extend over a length (L),the distributing opening (42) allowing the distribution of a gas that can be admitted through the inlet opening (41) of the distribution chamber (40) to the annular space (30), and the collecting opening (52) allowing the collection of the gas distributed in the annular space (30) by the collecting chamber (50), characterized in that the hollow insert (20) comprises an insert body (20i) obtained by the assembly of a plurality of distinct intermediate insert pieces (20ip), each intermediate insert piece (20ip) having, by observation in cross-section with respect to the longitudinal axis (XX'), a shape defined by a first segment (R1), a second segment (R2) and a peripheral portion (C) connecting the first segment (R1) and the second segment (R2), which define between them an internal angle (a) strictly between 0° and 360°.

2. Reactor according to claim 1, in which each intermediate insert piece (20ip) has, by observation in cross-section with respect to the longitudinal axis (XX'), a fraction of a circle shape defined by a peripheral portion in the form of an arc of a circle (C) connecting the first segment in the form of a first radius (R1) and the second segment in the form of a second radius (R2).

3. Reactor according to claim 1 or 2, wherein the junction between the first segment (R1) and the second segment (R2) is curved and has an internal radius of curvature, the internal angle (a) being different from 180°.

4. Reactor according to any one of the preceding claims, wherein the junction between the first segment (R1) and the peripheral portion (C) and / or the junction between the second segment (R2) and the peripheral portion (C) is curved and has an external radius of curvature.

5. Reactor according to any one of the preceding claims, wherein the number of intermediate insert pieces (20ip) is greater than or equal to 2, in particular greater than or equal to 4, in particular less than or equal to 6.

6. Reactor according to any one of the preceding claims, wherein the plurality of intermediate insert pieces (20ip) comprises four intermediate insert pieces (20ip), each intermediate insert piece (20ip) having, by observation in cross-section with respect to the longitudinal axis (XX'), a quarter-round shape, the internal angle (a) being substantially equal to 90°.

7. Reactor according to any one of the preceding claims, wherein the plurality of intermediate insert pieces (20ip) comprises at least two intermediate insert pieces (20ip) axially offset such that there is at least one cross-section with respect to the longitudinal axis (XX'), located in a non-reactive zone (NRZ) of the tubular reactor (1), in which only a part of said at least two intermediate insert pieces (20ip) is observed.

8. Reactor according to claim 7, wherein there is at least one cross-section with respect to the longitudinal axis (XX'), located in a reactive zone (ZR) of the tubular reactor (1), in which all the intermediate insert pieces (20ip) are observed.

9. Reactor according to any one of the preceding claims, wherein two adjacent intermediate insert pieces (20ip) are fixed together, in particular by welding and / or brazing, in particular at a meeting zone (S), forming a longitudinal groove, connecting the junction between the peripheral portion (C) and the first segment (R1) or second segment (R2) of a first intermediate insert piece (20ip) and the junction between the peripheral portion (C) and the first segment (R1) or second segment (R2) of a second intermediate insert piece (20ip), adjacent to the first intermediate insert piece (20ip).

10. Reactor according to any one of the preceding claims, wherein the hollow insert (20) comprises centering means (22) maintaining the hollow insert (20) in a substantially coaxial position with the hollow tube (10), the centering means (22) being in particular in the form of centering pins disposed at the level of a meeting zone (S), forming a longitudinal groove, connecting the junction between the peripheral portion (C) and the first segment (R1) or second segment (R2) of a first intermediate insert piece (20ip) and the junction between the peripheral portion (C) and the first segment (R1) or second segment (R2) of a second intermediate insert piece (20ip), adjacent to the first intermediate insert piece (20ip).

11. Reactor according to claim 10, wherein the centering means (22) are fixed to the insert body (20i), in particular by welding and / or brazing.

12. Reactor according to any one of the preceding claims, wherein each intermediate insert piece (20ip) is obtained by means of a drawing process.

13. Reactor according to any one of the preceding claims, wherein each intermediate insert piece (20ip) is obtained by means of a rolling and welding process.

14. Reactor according to any one of the preceding claims, wherein the assembly of the intermediate insert parts (20ip) is obtained by fitting, welding, brazing and / or joining intermediate insert parts (20ip) in the form of collars of substantially circular cross-section.

15. Reactor according to any one of the preceding claims, wherein the insert body (20i) is made of iron, nickel, iron alloy and / or nickel alloy.

16. Reactor according to any one of the preceding claims, wherein the external diameter (De) of the insert body (20i) is less than 5 cm, in particular less than 3 cm.

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