Heat exchange reactor sealing device

Abstract

A tube sealing device suitable for use in a heat exchange reactor comprising one or more tubes is described, the tube sealing device comprising a seal tube and an inner tube disposed within the seal tube to provide an overlap region, the inner tube having within the overlap region (i) an internal constriction of reduced cross-sectional area forming a low pressure region, (ii) an expansion region adjacent the constriction of a cross-sectional area greater than the cross-sectional area of ​​the constriction, and (iii) one or more passageways through a wall of the inner tube connecting the low pressure region to an exterior of the inner tube, the tube sealing device further comprising one or more grooves formed around an inner surface of the seal tube in the overlap region corresponding to the low pressure region of the inner tube.

Description

Technical Field

[0001] The present invention relates to a sealing device, the use of the sealing device in a heat exchange reactor, and a process using such a device, particularly a catalytic steam reforming process.

[0002] In a heat exchange reactor device including a tube heated from the outside, there is a significant difference in thermal expansion between means such as a tube sheet that defines the boundary of the zone through which the heat exchange medium passes in the heat exchange between the tube carrying the process fluid and the process fluid passing through the tube. When the tube is heated by a heat exchange medium flowing around the outside of the tube at a lower pressure than the process fluid passing through the tube, one solution was to employ a sealing device connected to each tube, comprising a sealing tube and an inner tube movably disposed within the sealing tube, the inner tube having a constriction that provides a low-pressure region and a passage through the wall of the inner tube that connects the low-pressure region to the outside of the inner tube. In this way, mixing of the process fluid and the heat exchange medium is prevented or reduced. WO 97 / 05947 discloses such a device.

[0003] The present applicant has found that by generating a turbulent flow in the annular space between the outside of the inner tube and the inside of the sealing tube, thereby disturbing the flow of the heat exchange medium within the sealing device, the amount of mixing between the heat exchange medium and the process fluid can be reduced.

[0004] Therefore, the present invention provides a tube sealing device suitable for use in a heat exchange reactor comprising one or more tubes, the tube sealing device comprising a sealing tube and an inner tube disposed within the sealing tube to provide an overlapping region, the inner tube having within the overlapping region: (i) an internal constriction with a reduced cross-sectional area that forms a low-pressure region; (ii) an expansion region adjacent to the constriction having a cross-sectional area larger than that of the constriction; and (iii) one or more passages through the wall of the inner tube that connect the low-pressure region to the outside of the inner tube, and the tube sealing device further comprising one or more grooves formed around the inner surface of the sealing tube in the overlapping region corresponding to the low-pressure region of the inner tube.

[0005] The present invention further provides a heat exchange reactor including one or more heat exchange tubes including a tube sealing device, and a process using the reactor and the tube sealing device.

[0006] Heat exchange reactors that include tube sealing devices are particularly useful when the heat exchange medium flowing around the outside of the tube is at a lower pressure than the process fluid passing through the tube.

[0007] By providing grooves inside the sealing tube rather than on the outside of the inner tube, fouling of the inner tube by material carried there by the heat exchange medium is reduced. This improves the long-term performance of the tube sealing device and simplifies maintenance by allowing fouled sealing tubes to be replaced during routine maintenance. Furthermore, providing grooves inside the sealing tube allows for potentially more grooves to be present.

[0008] To further reduce mixing between the process fluid and the heat exchange medium, one or more grooves may be additionally present in the overlapping region corresponding to the expansion region of the inner tube. These one or more grooves within the expansion region may be located on the outer surface of the inner tube or on the inner surface of the seal tube. Preferably, the one or more grooves within the overlapping region corresponding to the expansion region of the inner tube are located on the outer surface of the inner tube because this simplifies manufacturing.

[0009] A heat exchange reactor apparatus including a tube sealing device may include a process fluid supply zone, a heat exchange zone, and a process fluid extraction zone, a first boundary means and a second boundary means separating the zones from each other, and one or more heat exchange tubes fixed to one of the boundary means and extending through the heat exchange zone. Process fluid may flow from the process fluid supply zone through one or more heat exchange tubes into the process fluid extraction zone. Each heat exchange tube is provided with a tube sealing device. The sealing tube of the tube sealing device may be fixed to one of the boundary means. The inner tube of the tube sealing device is provided on each heat exchange tube. The sealing tube is arranged substantially coaxially with the inner tube such that the inner tube slides into its associated sealing tube, thereby forming an overlapping region.

[0010] Each inner tube of the tube sealing device is provided with (i) an internal constriction with a reduced cross-sectional area that forms a low-pressure region within the inner tube, (ii) an expansion region having a larger cross-sectional area downstream of the constriction, and (iii) one or more passages through the wall of the inner tube that connect the low-pressure region to the outside of the inner tube, the passages being located within the overlapping region, thereby providing a flow path for a fluid to enter the low-pressure region within the inner tube from the heat exchange zone through the overlapping region.

[0011] Each pipe sealing device includes one or more grooves formed around the inner surface of the sealing pipe in overlapping regions corresponding to the low-pressure region of the inner pipe.

[0012] In the heat exchange reactor of the type described above, the process fluid is passed from the process fluid supply zone through one or more heat exchange tubes located within a heat exchange zone defined by a casing through which the heat exchange medium passes, and then into a process fluid extraction zone. Means such as a tube sheet are provided to separate the zones. Thus, the tube sheet may separate the heat exchange zone through which the heat exchange medium passes from a zone such as a plenum chamber that communicates with the inside of the heat exchange tubes and allows for the supply of process fluid to or the extraction of process fluid from the tubes. An alternative configuration involves defining the process fluid supply zone using a header pipe located within the heat exchange zone, through which the process fluid is supplied to the header pipe and flows into and passes through the heat exchange tubes. Similarly, a header pipe may be provided for the extraction of process fluid from the tubes. Alternatively, there may be a combination of a tube sheet and a header pipe. Such a tube sheet or header defines the boundary between the heat exchange zone and the process fluid supply and extraction zones, and is therefore referred to herein as a boundary means.

[0013] By providing an inner tube on the heat exchange tube, and by connecting a sealing tube to the boundary means within the heat exchange reactor, longitudinal movements caused by thermal expansion and contraction of the heat exchange tube can be accommodated.

[0014] During use, due to the low-pressure region within the inner tube, the heat exchange medium may be drawn into the interior of the inner tube, where it mixes with the process fluid flowing through the inner tube.

[0015] A heat exchange reactor may comprise one or more heat exchange tubes, for example, 1 to 10 tubes, but a heat exchange reactor used in a steam reforming process, for example, may comprise tens or even hundreds of tubes, for example, 10 to 2000 tubes. The tubes may have an inner diameter of 25 to 150 mm, and the wall thickness of the tubes may range from 2 to 13 mm depending on the size of the tubes. The tubes may be 5 to 15 meters long. At such lengths, especially 10 to 15 meters, longitudinal expansion becomes a particular problem if a tube sealing device is not used. The tubes may be manufactured from a suitable metal such as stainless steel. The heat exchange reactor may be equipped with one or more transverse baffles to move the heat exchange medium in a meandering manner through the heat exchange zone, thereby improving heat exchange.

[0016] The pipe sealing device comprises an inner tube. The inner tube may be connected to one end of the heat exchange tube, or may be formed as the end of the heat exchange tube. The inner tube may have the same diameter as the heat exchange tube, or preferably a narrower diameter. The inner tube may be polygonal or cylindrical, but it is preferable that it is shaped such that a uniform gap space is formed between the outer surface of the inner tube and the inner surface of the sealing tube in the overlapping region. The inner tube has an internal constriction that forms a low-pressure region inside the tube, and an expanded portion adjacent to the constriction that forms an expansion zone inside the tube. One or more passages through the wall of the inner tube connect the low-pressure region to the outside of the inner tube. There may be 1 to 20 passages connecting the low-pressure region to the outside of the inner tube. It is desirable that the passages be arranged at equal intervals so as to open into the gap space between the inner tube and the sealing tube. When in use, the device is oriented so that the expansion zone is located downstream of the low-pressure zone. For example, in a vertical downflow configuration where the pipe sealing device is located at the lowest end of the heat exchange tube, the expansion region is below the constriction of the inner tube. The relative sizes of the constricted section, the low-pressure region, and the expansion region depend in part to the size of the tube. For example, in one embodiment including a heat exchange tube with an inner diameter of approximately 100 mm, the portion of the tube forming the inner tube may have an internal dimension of approximately 25 mm, tapering internally to a constricted section with an inner diameter of approximately 12 mm that opens into a low-pressure region with an inner diameter of approximately 18 mm and a length of approximately 108 mm. At the end of the low-pressure region, the inner tube may flare over a length of approximately 78 mm from a diameter of 18 mm to an outer diameter of approximately 31 mm. Twelve equally spaced passages with a diameter of 3 mm may be provided between the low-pressure region and the outside of the inner tube.

[0017] A gap, such as an annular gap, exists in the overlapping region between the inner surface of the sealing tube and the outer surface of the inner tube. This allows the inner tube to move freely in the longitudinal direction within the sealing tube. The thickness of the gap between the inner surface of the sealing tube and the outer surface of the inner tube portion of the heat exchange tube may be about 0.1 to 0.5 mm. For example, in the embodiment described above, the gap may be about 0.2 mm.

[0018] The pipe sealing device also includes a sealing tube. The sealing tube may be polygonal or cylindrical, but it is preferable that it has the same shape as the inner tube so that a uniform gap space is maintained. A pipe sealing device comprising a cylindrical sealing tube and a cylindrical inner tube is preferred because it is simpler to manufacture and more suitable for use at high temperatures under pressure.

[0019] The pipe sealing device includes one or more grooves on the inner surface of the sealing pipe. These one or more grooves are formed on the inner surface of the sealing pipe in overlapping regions corresponding to the low-pressure region of the inner pipe. The one or more grooves on the inner surface of the sealing pipe may be formed as crenations, i.e., having a square or rectangular shape, or the grooves may be U-shaped, V-shaped, or any combination thereof. Square or rectangular grooves can provide improved turbulence in the overlapping region.

[0020] The grooves may be formed by cutting one or more channels into the inner surface of the sealing tube device. Alternatively, the grooves may be formed without cutting, for example, by using a layered configuration of rings with different inner diameters inside the sealing tube device, or by rolling a grooved outer shape into the sealing tube device.

[0021] The groove size may be 2 to 20 mm wide, for example 6 to 14 mm wide and 1 to 7 mm deep, depending on the size of the pipe and the thickness of the pipe wall. Preferably, the groove depth is about 50% or less of the pipe wall thickness for strength reasons. In the overlapping region corresponding to the low-pressure region of the inner pipe, there may be 1 to 30 grooves, for example 2 to 25 grooves, preferably 5 to 20 grooves, located on the seal pipe. This is an improvement over devices where the grooves are located on the inner pipe and the number of grooves in this region is limited to 8 or less depending on the size of the inner pipe. By arranging the grooves on the inner wall of the seal pipe, the grooves can extend beyond the low-pressure region.

[0022] In addition, there may be one or more grooves in the overlapping region corresponding to the expansion region of the inner tube. Whether the one or more grooves are on the outer surface of the inner tube or on the inner surface of the seal tube, they may be formed as crenation, i.e., having a square or rectangular shape, or the grooves may be U-shaped, V-shaped, or any combination thereof. The size of the grooves in this region may also be 2 to 20 mm in width, for example, 6 to 14 mm in width and 1 to 7 mm in depth. The number of grooves in the expansion region may be the same as or greater than the number of grooves in the low-pressure region. For example, 1 to 30 grooves, for example 2 to 25 grooves, preferably 5 to 20 grooves, located on the inner surface of the seal tube or the outer surface of the inner tube may be in the overlapping region corresponding to the expansion region of the inner tube.

[0023] Preferably, one or more grooves are positioned to obstruct the flow of gas through the tube sealing device. The one or more grooves may be positioned perpendicular to the flow of process fluid through the inner tube, or the grooves may be formed in a helical shape, such as a screw thread.

[0024] If two or more grooves exist in either the low-pressure region or the expansion region, it is preferable that they be parallel to each other.

[0025] The present invention relates to a process comprising: (a) supplying a process fluid to a heat exchange reactor having a process fluid supply zone separated from a heat exchange zone by boundary means; (b) passing the process fluid from the process fluid supply zone through one or more heat exchange tubes extending through the heat exchange zone, wherein the process fluid is subjected to heat exchange with a heat exchange medium at a lower pressure than the process fluid passing through the tubes in the heat exchange zone; (c) sending the process fluid from the heat exchange tubes to a process fluid extraction zone separated from the heat exchange zone by a second boundary means; (d) subjecting the process fluid from the process fluid extraction zone to a further processing step; and (e) passing the obtained processed process fluid through the heat exchange zone as a heat exchange medium. The process further provides a process comprising: each of the one or more heat exchange tubes being fixed to one of the boundary means and engaging with the other of the boundary means by a tube sealing device, the tube sealing device comprising a sealing tube fixed to the other of the boundary means and an inner tube connected to each heat exchange tube and disposed within the sealing tube to provide an overlapping region, the inner tube having within the overlapping region (i) an internal constriction with a reduced cross-sectional area that forms a low-pressure region, (ii) an expansion region of the low-pressure region having a cross-sectional area larger than the cross-sectional area of ​​the constriction downstream in the flow direction of the process fluid, and (iii) one or more passages through the wall of the inner tube that connect the low-pressure region to the outside of the inner tube, the tube sealing device comprising one or more grooves formed around the inner surface of the sealing tube in the overlapping region corresponding to the low-pressure region of the inner tube.

[0026] In the process, a portion of the treated process fluid supplied to the heat exchange zone enters a pipe sealing device and enters a low-pressure region through one or more passages.

[0027] In the process, the heat exchange medium is a process fluid that has passed through a tube, but has been subjected to further treatment before being used as a heat exchange medium. This further treatment preferably includes a step in which the process fluid is heated so that the heat exchange medium transfers heat to one or more heat exchange tubes.

[0028] The tube sealing device includes one or more external heating tubes including a steam reforming catalyst for passing a reformer feed to generate synthesis gas, and is particularly useful in a heat exchange reactor where heat exchange is used as a medium for heating the tubes. In such a process, the heat exchange medium is typically at a lower pressure than the reformer feed.

[0029] This process and apparatus are particularly useful for the steam reforming of hydrocarbons, where a mixture of a hydrocarbon feedstock and steam is passed through a heat exchange tube containing a steam reforming catalyst, such as a nickel-containing steam reforming catalyst, to form a primary reformed gas. The primary reformed gas is then subjected to partial combustion with an oxygen-containing gas, and the resulting partially combusted gas is used as the heat exchange medium in the heat exchange zone. Preferably, the partially combusted gas is passed through a bed of a secondary reforming catalyst for further reforming before being used as the heat exchange medium.

[0030] As a result of the constriction in the inner tube, a low-pressure region is formed within the inner tube. By appropriately sizing the constriction, the pressure within the low-pressure region during normal operation can be lower than the pressure within the heat exchange zone, such that a heat exchange medium, such as the secondary reformed product of a process fluid withdrawn from a process fluid extraction zone, flows from the heat exchange zone through the gap space between the seal tube and the inner tube and through the passage in the wall of the inner tube into the low-pressure region. Downstream of the low-pressure region, the process fluid expands in an expansion region that provides a process fluid pressure higher than that of the low-pressure region. As a result, the process fluid may flow back or recirculate from the outlet end of the inner tube, through the gap space, into the passage, and into the low-pressure region.

[0031] The tube sealing device is preferably provided at the boundary means between the heat exchange zone and the process fluid extraction zone. Thus, the sealing tube is preferably fixed to the boundary means, while one or more heat exchange tubes including the inner tube are fixed to the boundary means between the process fluid inlet zone and the heat exchange zone, such as a tube sheet. In this configuration, the inner tube is formed at the end of the heat exchange tube adjacent to the boundary means between the heat exchange zone and the process fluid extraction zone, and thus engages with the sealing tube at this boundary means to form a tube sealing device. This is particularly preferred when the process fluid undergoes a substantial pressure drop when passing through the heat exchange tube, for example when the heat exchange tube contains a catalyst. The sealing tube may protrude into the heat exchange zone from the boundary means, or on the opposite side of the boundary means, extend into the process fluid extraction zone so as to return from the boundary means.

[0032] In steam reforming, the hydrocarbon feedstock is typically a methane-containing gas. During the reforming process, methane reacts with steam to produce hydrogen and carbon oxides. Any hydrocarbon containing two or more carbon atoms present is converted to methane, carbon monoxide, and hydrogen. The steam reforming reaction is carried out in a tube on a steam reforming catalyst at a temperature above 350 °C, and typically the process fluid exiting the tube is at a temperature in the range of 650 - 950 °C. The heat exchange medium flowing outside the tube can have a temperature in the range of 500 - 2000 °C.

[0033] The present apparatus and process can be used as part of a process for the production of hydrogen, methanol, dimethyl ether, olefins, ammonia, urea, or hydrocarbon liquids (e.g., diesel fuel) obtained by Fischer-Tropsch synthesis. Thus, the reformed gas mixture obtained using the apparatus of the present invention or in the process of the present invention may be subjected to further process steps including hydrogen separation, methanol synthesis, dimethyl ether synthesis, olefin synthesis, ammonia synthesis, or hydrocarbon liquid synthesis. Known processes can be used to achieve these steps.

[0034] Although the above has been primarily described in relation to heat-exchange steam reforming, it will be understood that the present invention is also useful for other heat exchange applications where a considerable difference in thermal expansion must be accommodated and leakage of the heat exchange medium into the process fluid is undesirable. An example is a feed / waste heat exchanger in which a feed product into a process step, such as an exothermic reaction like methanol or ammonia synthesis, is heated by heat exchange with wastewater from the process step. In such cases, the heat exchange tube does not need to contain a catalyst, unless it is desired that a catalytic reaction occur in the process fluid while the process fluid is undergoing heat exchange, as in the reforming process described above. [Brief explanation of the drawing]

[0035] The present invention will be further described by reference to the accompanying drawings.

[0036] [Figure 1] This is a schematic cross-sectional view of a heat exchange reactor incorporating a tube sealing device according to one embodiment of the present invention, wherein the boundary means is a tube sheet. [Figure 2] This is a cross-sectional view of a pipe sealing device according to one embodiment of the present invention.

[0037] Figure 1 shows a heat-exchange steam reformer having an outer adiabatic pressure shell 10 surrounding three zones 11, 12, and 13 defined by shell walls and tube sheets 14 and 15. Zone 11, which is the process fluid supply zone, is defined by the shell walls 10 and tube sheets 14. Zone 11 is provided with process fluid supply conduits 16 and has several vertical tubes 17 fixed to the tube sheets 14 and extending downward therefrom. The number of tubes employed depends on the scale of operation, and although only five tubes are shown, typically there can be 50 or more such tubes. The tubes 17 are filled with porous cylindrical pellets of steam reforming catalyst 18, such as refractory oxide-supported nickel catalyst and / or structured steam reforming catalyst. Zone 12, which is the heat exchange zone, is defined by the shell walls 10 and tube sheets 14 and 15. Heat exchange tubes 17 extend through the heat exchange zone 12 and engage with tube sealing devices 20. Each tube sealing device 20 comprises a sealing tube 21 fixed to the tube sheet 15 and engages with a catalyst-free inner tube portion 22 extending from the bottom of the catalyst-filled tube 17 in the heat exchange zone 12. A heating medium, such as synthesis gas produced by self-thermal reforming or secondary reforming, is supplied to the heat exchange zone 12 via a conduit 23 located within the shell 10 near the bottom of the tube 17. The heating medium passes upward through the heat exchange zone, exchanging heat with the tube 17, and is then removed from the heat exchange zone 12 via a conduit 24 located within the shell 10 near the top of the tube 17. Transverse baffles 25 act to redirect the heating medium horizontally across the reformer, thereby increasing heat exchange with the tube 17. Zone 13, which is the process fluid extraction zone, is defined by the walls of the shell 10 and the tube sheet 15. The tube sealing device 20 has an open end and extends through the tube sheet 15 into the extraction zone 13. The reformed gas enters the extraction zone 13 through the pipe 17 and pipe sealing device 20, from where it is removed by the process fluid extraction conduit 26.

[0038] During use, the process fluid, containing hydrocarbons and steam, is supplied at high temperature and pressure through conduit 16 to the process fluid supply zone 11, and from there it is supplied downward through catalyst-filled pipe 17. In the heat exchange zone 12, heat exchange occurs with the heat transfer medium, and a steam reforming reaction takes place. The gas mixture to be reformed passes through pipe 17, then through pipe sealing device 20 to the extraction zone 13, from where it is removed by extraction conduit 26. The reformed gas recovered from extraction conduit 26 is subjected to further treatment, particularly by self-thermal reforming or secondary reforming, and the further treated gas is sent to the heat exchange reformer via conduit 23 as a heat exchange medium. The pressure of the heat exchange medium supplied via conduit 23 is lower than that of the gas passing through pipe 17.

[0039] Figure 2 shows a pipe sealing device 20 oriented vertically and positioned for downward flow through the device according to the embodiment shown in Figure 1. The pipe sealing device 20 comprises an outer sealing pipe 21 and an inner pipe 22. The inner pipe 21 is located inside the sealing pipe 22, providing an overlapping region, and slides freely in the vertical direction. When in use, the inner pipe 22 is fixed to the bottom 30 of the heat exchange pipe. The connection between the bottom 30 of the heat exchange pipe and the inner pipe 22 has an inner diameter of 25 mm and does not contain a catalyst. The inner pipe 22 tapers from an inner diameter of 25 mm to a constricted section 31 with an inner diameter of 12 mm, and then expands from the constricted section 31 to a low-pressure region 32 with an inner diameter of 18 mm and a length of 108 mm. The inner pipe expands over a length of 78 mm from the diameter of the low-pressure region 32 to the outer diameter of the expansion region 33 with an outer diameter of 31 mm. Twelve passages 34 with a diameter of 3 mm are provided between the low-pressure region 32 downstream of the constricted section 31 and the annular gap 35 between the inner surface of the seal pipe 21 and the outer surface of the inner pipe 22. The thickness of the annular gap 35 between the seal pipe 21 and the outer surface of the inner pipe 22 is 0.2 mm.

[0040] The seal tube 21 includes seven parallel 7 mm wide square cut grooves 36 cut into the inner surface of the seal tube 21 facing the inner tube 22 in the overlapping region. The grooves extend upward from a position within the low-pressure region 32 adjacent to the passage 34 toward and beyond the point where the inner tube 22 connects to the lowest part 30 of the heat exchange tube. It can be seen that by providing the grooves in this way, it is possible to have more grooves than if the grooves were cut into the outer surface of the inner tube 22.

[0041] In this embodiment, six parallel 7 mm wide right-angle cutting grooves 37 are further cut into the outer surface of the inner tube 22, extending downward toward the expansion region 33 from a position adjacent to the passage 34.

[0042] The lengths of the inner tube 22 and the sealing tube 21 are such that, at startup, i.e., when the device is at ambient temperature and at normal operating temperature, the open ends of the passage 34 and the inner tube 22 are located inside the sealing tube 21.

[0043] The flange 38 is provided at the bottom of the sealing tube 21, extending beyond the edge of the overlapping region, to allow the tube sealing device 20 to be secured to the tube sheet.

Claims

1. A tube sealing device suitable for use in a heat exchange reactor having one or more tubes, wherein the tube sealing device comprises a sealing tube (21) and an inner tube (22) disposed within the sealing tube and providing an overlapping region, the inner tube having within the overlapping region (i) an internal constriction (31) with a reduced cross-sectional area that forms a low-pressure region (32), (ii) an expansion region (33) adjacent to the internal constriction having a cross-sectional area larger than the cross-sectional area of ​​the internal constriction, and (iii) one or more passages (34) passing through the wall of the inner tube that connect the low-pressure region to the outside of the inner tube, and the tube sealing device further comprises one or more grooves (36) arranged to obstruct the flow of gas through the tube sealing device, wherein the one or more grooves are formed around the inner surface of the sealing tube (21) in the overlapping region corresponding to the low-pressure region of the inner tube, the tube sealing device (20).

2. The pipe sealing device according to claim 1, wherein one or more grooves are additionally provided in the overlapping region corresponding to the expansion region (33) of the inner pipe (22).

3. The tube sealing device according to claim 2, wherein the one or more grooves within the expansion region are provided on the outer surface of the inner tube (22) or on the inner surface of the sealing tube (21).

4. The pipe sealing device according to any one of claims 1 to 3, comprising 1 to 30 grooves located on the sealing pipe (21) in the overlapping region corresponding to the low-pressure region (32) of the inner pipe (22).

5. The pipe sealing device according to any one of claims 1 to 4, wherein the one or more grooves (36) have a square or rectangular shape, or are U-shaped, V-shaped, or any combination thereof.

6. A heat exchange reactor comprising one or more heat exchange tubes (17) including a tube sealing device according to any one of claims 1 to 5.

7. A heat exchange reactor according to claim 6, comprising: a process fluid supply zone (11), a heat exchange zone (12), and a process fluid extraction zone (13); a first boundary means (14) separating the process fluid supply zone (11) and the heat exchange zone (12) from each other; a second boundary means (15) separating the heat exchange zone (12) and the process fluid extraction zone (13) from each other; one or more heat exchange tubes (17) fixed to one of the boundary means and extending through the heat exchange zone; and a tube sealing device (20) for each heat exchange tube, wherein the tube sealing device comprises a sealing tube (21) and an inner tube (22), the sealing tube of the tube sealing device being fixed to one of the boundary means and being substantially coaxial with the inner tube such that the inner tube slides into engagement with its associated sealing tube, thereby forming an overlapping region.

8. The heat exchange reactor according to claim 7, wherein the heat exchange tube includes a steam reforming catalyst.

9. The heat exchange reactor according to claim 7 or 8, wherein the tube sealing device is fixed to the second boundary means (15) between the heat exchange zone (12) and the process fluid extraction zone (13).

10. The heat exchange reactor according to claim 8 or 9, in the form of a heat exchange steam reformer, wherein the process fluid passes through the heat exchange tube and is operably connected to a partial combustion means designed to cause partial combustion of the process fluid and supply the gas after partial combustion to a heat exchange steam reformer as a heat exchange medium.

11. The heat exchange reactor according to claim 10, wherein the partial combustion means includes a reforming catalyst bed through which the gas after partial combustion passes before being supplied to the heat exchange steam reformer as the heat exchange medium.

12. A process comprising: (a) supplying a process fluid to a heat exchange reactor having a process fluid supply zone (11) separated from a heat exchange zone (12) by boundary means (14); (b) passing the process fluid from the process fluid supply zone through one or more heat exchange tubes (17) extending through the heat exchange zone, wherein the process fluid is subjected to heat exchange with a heat exchange medium at a lower pressure than the process fluid passing through the heat exchange tubes in the heat exchange zone; (c) sending the process fluid from the heat exchange tubes to a process fluid extraction zone (13) separated from the heat exchange zone by a second boundary means (15); (d) subjecting the process fluid from the process fluid extraction zone to a further processing step; and (e) passing the obtained processed process fluid through the heat exchange zone (12) as the heat exchange medium, wherein each of the one or more heat exchange tubes (17) is the boundary means A process comprising: fixed to one of the boundary means by a pipe sealing device, the pipe sealing device comprising: a sealing pipe (21) fixed to the other of the boundary means; and an inner pipe (22) connected to each heat exchange pipe and disposed within the sealing pipe to provide an overlapping region, wherein the inner pipe has within the overlapping region: (i) an internal constriction with a reduced cross-sectional area that forms a low-pressure region (32); (ii) an expansion region (33) of the low-pressure region having a cross-sectional area larger than the cross-sectional area of ​​the internal constriction downstream in the flow direction of the process fluid; and (iii) one or more passages (34) through the wall of the inner pipe that connect the low-pressure region to the outside of the inner pipe, wherein the pipe sealing device includes one or more grooves (36) arranged to obstruct the flow of gas through the pipe sealing device, the one or more grooves being formed around the inner surface of the sealing pipe (21) in the overlapping region corresponding to the low-pressure region of the inner pipe.

13. The process according to claim 12, wherein the heat exchange reactor includes a heat exchange steam reformer that includes one or more external heating tubes containing a steam reforming catalyst, wherein a reformer feed is passed through the steam reforming catalyst to produce synthesis gas, and the heat exchange medium used to heat the heat exchange tubes is at a lower pressure than the reformer feed.

14. The process according to claim 13, wherein the heat exchange steam reformer is operably connected to a partial combustion means designed to cause partial combustion of the process fluid after the process fluid has passed through the heat exchange tube, and to supply the gas after the partial combustion to the heat exchange steam reformer as a heat exchange medium.

15. The process according to claim 14, wherein the partial combustion means includes a reforming catalyst bed through which the gas after partial combustion passes before being supplied to the heat exchange steam reformer as the heat exchange medium.

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