Heat exchange reactor seal

Abstract

A tube seal for a heat exchange reactor comprising one or more tubes is described, the tube seal 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 which forms a low pressure region, (ii) adjacent the constriction, an expansion region of greater cross-sectional area than the constriction and (iii) one or more passages through the wall of the inner tube connecting the low pressure region to the exterior of the inner tube, wherein the tube seal further comprises one or more grooves formed around the inner surface of the seal tube in the overlap region corresponding to the low pressure region of the inner tube.

Description

[0001] This invention relates to sealing devices and their use in heat exchange reactors, as well as processes using such devices, particularly in catalytic steam reforming processes.

[0002] In heat exchange reactor devices containing external heating tubes, significant differential thermal expansion can easily exist between the tubes carrying the process fluid and the device, such as a tube sheet, thus defining the boundary of the area traversed by the heat exchange medium and the process fluid passing through the tubes during heat exchange. When the tubes are heated by a heat exchange medium flowing outside the tubes (with a pressure lower than that of the process fluid passing through the tubes), one solution is to employ a sealing device connected to each tube. This sealing device includes a sealing tube and an inner tube movably disposed within the sealing tube. The inner tube has a contraction section providing a low-pressure region and also has a channel through the wall of the inner tube connecting 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. WO9705947 discloses such a device.

[0003] The inventors have discovered that by generating turbulence in the annular space between the outside of the inner tube and the inside of the sealing tube to disrupt 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 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 in the overlapping region: (i) an internal contraction with a reduced cross-sectional area forming a low-pressure region, (ii) an expansion region adjacent to the contraction with a cross-sectional area larger than that of the contraction, and (iii) one or more channels through the wall of the inner tube connecting the low-pressure region to the outside of the inner tube, wherein the tube sealing device further comprises 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 also provides a heat exchange reactor comprising one or more heat exchange tubes having a tube sealing device, and a process for using the reactor and the tube sealing device.

[0006] Heat exchange reactor devices, including tube sealing devices, are particularly useful when the pressure of the heat exchange medium flowing outside the tubes is lower than the pressure of the process fluid flowing through the tubes.

[0007] By providing grooves inside the sealing tube, rather than on the outside, contamination of the inner tube due to substances carried into it by the heat exchange medium is reduced. This improves the long-term performance of the tube sealing device and simplifies maintenance by allowing replacement of contaminated sealing tubes during routine maintenance. Furthermore, providing grooves inside the sealing tube potentially allows for a greater number of grooves to be present.

[0008] To further reduce the mixing of process fluid and heat exchange medium, one or more grooves corresponding to the expansion region of the inner tube may be present in the overlapping region. These grooves in the expansion region may be located on the outer surface of the inner tube or on the inner surface of the sealing tube. Preferably, the one or more grooves corresponding to the expansion region of the inner tube in the overlapping region are provided on the outer surface of the inner tube, as 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 discharge zone; a first boundary device and a second boundary device separating the zones from each other; and one or more heat exchange tubes fastened to one of the boundary devices and extending through the heat exchange zone. Process fluid may flow from the process fluid supply zone through the one or more heat exchange tubes and into the process fluid discharge zone. Each heat exchange tube is provided with a tube sealing device. The sealing tube of the tube sealing device may be fastened to one of the boundary devices. An inner tube of the tube sealing device is disposed on each heat exchange tube. The sealing tube is substantially coaxial with the inner tube, such that the inner tube slides into contact with its associated sealing tube, thereby forming an overlap area.

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

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

[0012] In the heat exchange reactors of the type described above, the process fluid flows from the process fluid supply zone through one or more heat exchange tubes disposed within a heat exchange zone defined by a shell through which the heat exchange medium passes, and then into the process fluid discharge zone. Devices such as tube sheets are provided to separate these zones. Thus, the tube sheet separates the heat exchange zone through which the heat exchange medium passes from areas such as an aeration chamber that communicate with the interior of the heat exchange tubes, allowing the process fluid to be supplied to or discharged from the tubes. An alternative arrangement involves using a manifold disposed within the heat exchange zone to define the process fluid supply zone: the process fluid is supplied to the manifold, flows from the manifold into and through the heat exchange tubes. Similarly, a manifold can be provided for discharging the process fluid from the tubes. Alternatively, a combination of tube sheets and manifolds may be present. Such tube sheets or manifolds are referred to herein as boundary devices because they define the boundary between the heat exchange zone and the process fluid supply and discharge zones.

[0013] By installing an inner tube on the heat exchange tube and connecting the sealing tube to the boundary device in the heat exchange reactor, the longitudinal movement caused by the thermal expansion and contraction of the heat exchange tube can be accommodated.

[0014] During use, due to the low-pressure area in the inner tube, the heat exchange medium can 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 contain one or more heat exchange tubes, such as 1 to 10 tubes, but a heat exchange reactor for a steam reforming process, for example, may contain dozens or even hundreds of tubes, such as 10 to 2000 tubes. The tubes may have an inner diameter of 25 mm to 150 mm, and depending on the tube size, the wall thickness may range from 2 mm to 13 mm. The tubes may have a length of 5 meters to 15 meters. At such lengths, particularly 10 to 15 meters, longitudinal expansion becomes particularly problematic without the use of tube sealing devices. The tubes may be made of suitable metals such as stainless steel. The heat exchange reactor may include one or more transverse baffles to allow the heat exchange medium to move in a serpentine manner through the heat exchange zone, thereby enhancing heat exchange.

[0016] The tube sealing device includes an inner tube. The inner tube may be connected to one end of a heat exchange tube, or may be formed as an end portion 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 is preferably 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 contraction portion that forms a low-pressure region within the tube and an expansion portion adjacent to the contraction portion that forms an expansion region within the tube. One or more channels through the wall of the inner tube connect the low-pressure region to the outside of the inner tube. There may be one to 20 channels connecting the low-pressure region to the outside of the inner tube. The channels are ideally uniformly spaced to lead to the gap space between the inner tube and the sealing tube. In use, the device is oriented such that the expansion region is downstream of the low-pressure region. For example, in a vertical downflow arrangement, when the tube sealing device is located at the lowermost end of the heat exchange tube, the expansion region will be located below the contraction portion in the inner tube. The relative dimensions of the contraction section, the low-pressure region, and the expansion region will depend in part on the tube size. 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, thereby tapering inward to a contraction section with an inner diameter of approximately 12 mm, which leads to 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 expand from an 18 mm diameter to an outer diameter of approximately 31 mm over a length of approximately 78 mm. Twelve evenly spaced channels with a diameter of 3 mm may be provided between the low-pressure region and the outside of the inner tube.

[0017] In the overlapping region, a gap, such as an annular gap, exists between the inner surface of the sealing tube and the outer surface of the inner tube. This allows the inner tube to move freely longitudinally 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 can be approximately 0.1 mm to 0.5 mm. For example, in the above embodiment, the gap can be approximately 0.2 mm.

[0018] The pipe sealing device also includes a sealing tube. The sealing tube can be polygonal or cylindrical, but preferably has the same shape as the inner tube in order to maintain a uniform gap space. Pipe sealing devices that include a cylindrical sealing tube and a cylindrical inner tube are preferred because these devices are easier to manufacture and more suitable for use under high temperature and pressure.

[0019] The pipe sealing device includes one or more grooves located on the inner surface of the sealing pipe. These grooves, in the overlapping region, correspond to the low-pressure region of the inner pipe. The grooves on the inner surface of the sealing pipe may be serrated, i.e., square or rectangular, or the grooves may be U-shaped, V-shaped, or any combination of these shapes. Square or rectangular grooves can provide improved turbulence in the overlapping region.

[0020] Grooves can be formed by cutting one or more channels into the inner surface of the sealing tube assembly. Alternatively, these grooves can be formed without cutting, for example by using a layered arrangement of rings with different inner diameters within the sealing tube assembly, or by rolling a grooved profile within the sealing tube assembly.

[0021] Depending on the pipe size and wall thickness, the groove can be 2 mm to 20 mm wide, for example, 6 mm to 14 mm wide, and 1 mm to 7 mm deep. Ideally, for strength reasons, the groove depth should not exceed approximately 50% of the pipe wall thickness. In the overlapping region, the sealing pipe may have 1 to 30 grooves corresponding to the low-pressure region of the inner pipe, for example, 2 to 25 grooves, preferably 5 to 20 grooves. This is an improvement on a device where the grooves are located on the inner pipe, wherein the number of grooves in this region is limited by the size of the inner pipe to 8 or less. By providing the grooves on the inner wall of the sealing pipe, the grooves can extend beyond the low-pressure region.

[0022] In the overlapping region, one or more grooves corresponding to the expansion region of the inner tube are additionally present. Whether the grooves are on the outer surface of the inner tube or the inner surface of the sealing tube, they can also be formed in a serrated shape, i.e., square or rectangular, or the grooves can be U-shaped, V-shaped, or any combination of these shapes. The dimensions of the grooves in this region can also be a width of 2 mm to 20 mm, for example, a width of 6 mm to 14 mm, and a depth of 1 mm to 7 mm. The same number or more grooves can exist in the expansion region compared to the low-pressure region. For example, in the overlapping region, the inner surface of the sealing tube or the outer surface of the inner tube may have 1 to 30 grooves corresponding to the expansion region of the inner tube, for example, 2 to 25 grooves, preferably 5 to 20 grooves.

[0023] One or more grooves are desiredly arranged to disrupt the flow of gas through the tube seal. The grooves may be arranged perpendicular to the flow of process fluid through the inner tube, or the grooves may be formed in a helical manner, such as a thread.

[0024] In the case of two or more grooves in a low-pressure region or an expansion region, they are preferably parallel to each other.

[0025] The present invention also provides a process comprising the steps of: (a) supplying a process fluid to a heat exchange reactor having a process fluid supply zone separated from a heat exchange zone by a boundary device; (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 exchanges heat with a heat exchange medium at a lower pressure than the process fluid passing through the tubes in the heat exchange zone; (c) transferring the process fluid from the heat exchange tubes to a process fluid discharge zone separated from the heat exchange zone by a second boundary device; (d) subjecting the process fluid from the process fluid discharge zone to further processing steps; and (e) passing the resulting treated process fluid as a heat exchange medium through the heat exchange zone, wherein the one or more heat exchange tubes... Each heat exchange tube in the heat exchange tube is fastened to one of the boundary devices and engaged with the other of the boundary devices by means of a tube sealing device, wherein the tube sealing device comprises a sealing tube fastened to the other of the boundary devices and an inner tube connected to each heat exchange tube and disposed within the sealing tube to provide an overlap region, the inner tube having in the overlap region: (i) an internal contraction with a reduced cross-sectional area forming a low-pressure region, (ii) an expansion region located downstream of the low-pressure region in the flow direction of the process fluid with a cross-sectional area larger than that of the contraction, and (iii) one or more channels through the wall of the inner tube connecting the low-pressure region to the outside of the inner tube, wherein the tube sealing device includes one or more grooves formed around the inner surface of the sealing tube in the overlap region corresponding to the low-pressure region of the inner tube.

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

[0027] In this process, the heat exchange medium is a process fluid that has passed through the tubes but has undergone further treatment before being used as a heat exchange medium. This further treatment preferably includes the step of heating the process fluid so that the heat exchange medium imparts heat to one or more heat exchange tubes.

[0028] Tube sealing devices are particularly useful in heat exchange steam reformers or gas-heated reformers, which are heat exchange reactors comprising one or more external heating tubes containing a steam reforming catalyst. The reformer feed passes through the steam reforming catalyst to produce syngas, and the heat exchange is performed using the medium for the heating tubes. In such processes, the heat exchange medium is typically at a lower pressure than the reformer feed.

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

[0030] Due to the contraction section in the inner tube, a low-pressure region is formed within the inner tube. By appropriately determining the size of the contraction section, the pressure in the low-pressure region can be lower than the pressure in the heat exchange region during normal operation. This allows the heat exchange medium (e.g., a secondary reforming product of the process fluid extracted from the process fluid discharge zone) to flow from the heat exchange region through the gap between the sealing tube and the inner tube, and through the channel in the inner tube wall into the low-pressure region. Downstream of the low-pressure region, the process fluid expands in the expansion region, thereby increasing the process fluid pressure to a level greater than that in the low-pressure region. Therefore, a return or recirculation of the process fluid from the outlet end of the inner tube through the gap to the channel and into the low-pressure region is also possible.

[0031] The tube sealing device is preferably located at a boundary device situated between the heat exchange zone and the process fluid discharge zone. Therefore, the sealing tube is preferably fastened to this boundary device, while one or more heat exchange tubes, including the inner tube, are fastened to the boundary device, such as a tube sheet, situated between the process fluid inlet zone and the heat exchange zone. In this arrangement, the inner tube is formed at the end of the heat exchange tube adjacent to the boundary device situated between the heat exchange zone and the process fluid discharge zone, and thus engages with the sealing tube at this boundary device to form the tube sealing device. This is particularly preferred when the process fluid experiences a significant pressure drop as it passes through the heat exchange tube, for example, when the heat exchange tube contains a catalyst. The sealing tube may protrude from the boundary device into the heat exchange zone, or it may extend rearward from the boundary device into the process fluid discharge zone on the other side of the boundary device.

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

[0033] This apparatus and process can be used as part of a process for producing hydrogen, methanol, dimethyl ether, olefins, ammonia, urea, or hydrocarbon liquids such as diesel fuel obtained through Fischer-Tropsch synthesis. Therefore, reformed gas mixtures obtained using the apparatus or process of this invention can undergo additional process steps, including hydrogen separation, methanol synthesis, dimethyl ether synthesis, olefin synthesis, ammonia synthesis, or hydrocarbon liquid synthesis. Known processes can be used to accomplish these steps.

[0034] Although the foregoing has primarily described heat-exchange steam reforming, it should be understood that the invention can also be used in other heat-exchange applications where considerable differential thermal expansion must be accommodated and leakage of the heat exchange medium into the process fluid is not undesirable. Examples include feed / effluent heat exchangers, for instance, in which the feed for a process step, such as an exothermic reaction (e.g., methanol or ammonia synthesis), is heated by heat exchange with the effluent from the process step. In this case, the heat exchange tube may be catalyst-free, unless, as in the aforementioned reforming process, catalytic reaction of the process fluid is required during heat exchange.

[0035] The present invention will be further described with reference to the accompanying drawings, wherein:

[0036] Figure 1 This is a schematic cross-section of a heat exchange reactor including a tube-sealed device according to an embodiment of the present invention, wherein the boundary device is a tube sheet; and

[0037] Figure 2 This is a cross-section of a pipe sealing device according to one embodiment of the present invention.

[0038] exist Figure 1The diagram illustrates a heat exchange steam reformer having an externally insulated pressure-resistant housing 10 enclosing three zones 11, 12, and 13 defined by housing walls and tube sheets 14 and 15. Zone 11, the process fluid supply zone, is defined by housing walls 10 and tube sheets 14. It is provided with process fluid supply conduits 16 and has a plurality of vertical tubes 17 fastened to and extending downward from tube sheets 14. The number of tubes used will depend on the scale of operation: although only five tubes are shown, typically 50 or more such tubes are possible. Tubes 17 are filled with steam reforming catalyst 18, such as porous cylindrical particles of refractory oxide-supported nickel catalyst and / or structured steam reforming catalyst. Zone 12, the heat exchange zone, is defined by housing walls 10 and tube sheets 14 and 15. Heat exchange tubes 17 extend through heat exchange zone 12 and engage with tube sealing devices 20. Each tube sealing device 20 includes a sealing tube 21 fixed to the tube sheet 15, which engages in the heat exchange zone 12 with a catalyst-free inner tube portion 22 extending from the bottom of a catalyst-filled tube 17. A heating medium, such as syngas produced by autothermal reforming or secondary reforming, is supplied to the heat exchange zone 12 via a conduit 23 located in the housing 10 near the bottom of the tube 17. The heating medium flows upward in the heat exchange zone, where it exchanges heat with the tube 17, and is then removed from the heat exchange zone 12 via a conduit 24 located in the housing 10 near the top of the tube 17. A transverse baffle 25 is used to deflect the heating medium horizontally through the reformer and enhance its heat exchange with the tube 17. Zone 13, the process fluid discharge zone, is defined by the walls of the housing 10 and the tube sheet 15. The tube sealing device 20 is open at the ends and extends through the tube sheet 15 into the discharge zone 13. The reformed gas passes through pipe 17, pipe sealing device 20, and enters discharge zone 13. The reformed gas is discharged from the discharge zone through process fluid discharge pipe 26.

[0039] In operation, a process fluid containing hydrocarbons and vapor is supplied to the process fluid supply zone 11 via pipe 16 at high temperature and pressure, and from there downwards through pipe 17 filled with catalyst. Heat exchange occurs with a heating medium in heat exchange zone 12, and a steam reforming reaction takes place. The reformed gas mixture passes through pipe 17 and from there through pipe sealing device 20 to discharge zone 13, from which the gas mixture is discharged through discharge pipe 26. The reformed gas recovered from discharge pipe 26 undergoes further processing, specifically by heating the reformed gas through autothermal reforming or secondary reforming, and the further processed gas is conveyed via pipe 23 as a heat exchange medium to a heat exchange reformer. The pressure of the heat exchange medium supplied via pipe 23 is lower than the pressure of the gas passing through pipe 17.

[0040] exist Figure 2 In China, according to Figure 1In the illustrated embodiment, the pipe sealing device 20 is shown vertically oriented and arranged in a downstream manner. The pipe sealing device 20 includes an outer sealing pipe 21 and an inner pipe 22. The inner pipe 21 is located within the sealing pipe 22 to provide an overlap area and slides freely vertically. In use, the inner pipe 22 is fixed to the lowest portion 30 of the heat exchange pipe. The connection between the lowest portion 30 of the heat exchange pipe and the inner pipe 22 has an inner diameter of 25 mm and is catalyst-free. The inner pipe 22 tapers from its 25 mm inner diameter to a 12 mm inner diameter contraction 31, and extends from the contraction 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 18 mm diameter of the low-pressure region 32 to an outer diameter of 31 mm in the expansion region 33. Twelve channels 34 with a diameter of 3 mm are provided between the low-pressure region 32 located downstream of the contraction section 31 and the annular gap 35 between the inner surface of the sealing tube 21 and the outer surface of the inner tube 22. The thickness of the annular gap 35 between the outer surface of the sealing tube 21 and the inner tube 22 is 0.2 mm.

[0041] The sealing tube 21 includes seven parallel, 7mm wide square cut grooves 36 that cut into the inner surface of the sealing tube 21 facing the inner tube 22 in overlapping areas. The grooves extend upwards from a position in the low-pressure region 32 adjacent to the channel 34 and beyond the point where the inner tube 22 connects to the lowest portion 30 of the heat exchange tube. It can be seen that providing grooves in this manner allows for a greater number of grooves than the grooves cut into the outer surface of the inner tube 22.

[0042] In this embodiment, six additional parallel 7mm wide square cutting grooves 37 cut downward toward the expansion region 33 from a position adjacent to the channel 34 into the outer surface of the inner tube 22.

[0043] The lengths of the inner tube 22 and the sealing tube 21 are such that the channel 34 and the open end of the inner tube 22 are both located inside the sealing tube 21 during startup, i.e. when the device is at ambient temperature and normal operating temperature.

[0044] The lowest portion of the sealing tube 21 has a flange 38 located outside the end of the overlapping area, so that the tube sealing device 20 can be secured to the tube sheet.

Claims

1. A tube sealing device (20) suitable for a heat exchange reactor comprising one or more tubes, the tube sealing device comprising a sealing tube (21) and an inner tube (22) disposed within the sealing tube to provide an overlapping region, the inner tube having in the overlapping region: (i) an internal contraction (31) with a reduced cross-sectional area forming a low-pressure region (32), (ii) an expansion region (33) adjacent to the internal contraction with a cross-sectional area larger than that of the contraction, and (iii) one or more channels (34) through the wall of the inner tube connecting the low-pressure region to the outside of the inner tube, wherein the tube sealing device further comprises one or more grooves (36) arranged to disrupt the flow of gas through the tube sealing device, the one or more grooves (36) being formed in the overlapping region around the inner surface of the sealing tube (21) corresponding to the low-pressure region of the inner tube.

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

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

4. The pipe sealing device according to claim 1, wherein the pipe sealing device comprises one 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 claim 1, wherein the one or more grooves (36) are square or rectangular in shape, or U-shaped, V-shaped or any combination of these shapes.

6. The pipe sealing device according to claim 1, wherein the one or more grooves (36) have a width in the range of 2 mm to 20 mm.

7. A heat exchange reactor comprising one or more heat exchange tubes (17), the one or more heat exchange tubes comprising the tube sealing device according to claim 1.

8. The heat exchange reactor according to claim 7, the heat exchange reactor comprising a process fluid supply zone (11), a heat exchange zone (12) and a process fluid discharge zone (13), a first boundary device (14) and a second boundary device (15) separating the zones from each other, one or more heat exchange tubes (17) fastened to the first boundary device or the second boundary device and extending through the heat exchange zone, and a tube sealing device (20) for each heat exchange tube, the tube sealing device comprising a sealing tube (21) and an inner tube (22), wherein the sealing tube of the tube sealing device is fastened to another boundary device and is substantially coaxial with the inner tube such that the inner tube slides into contact with its associated sealing tube to form the overlapping area.

9. The heat exchange reactor according to claim 8, wherein the heat exchange tube (17) contains a steam reforming catalyst (18).

10. The heat exchange reactor according to claim 8, wherein the heat exchange reactor includes one or more transverse baffles (25) in the heat exchange zone.

11. The heat exchange reactor according to claim 8, wherein the tube sealing device is fastened to the second boundary device (15) located between the heat exchange zone (12) and the process fluid discharge zone (13).

12. The heat exchange reactor of claim 8, wherein the heat exchange reactor is in the form of a heat exchange steam reformer operatively connected to a partial combustion device designed to partially combust the process fluid after it has passed through the one or more heat exchange tubes, and to supply gas as a heat exchange medium to the heat exchange steam reformer after the partial combustion.

13. The heat exchange reactor of claim 12, wherein the partial combustion device comprises a reforming catalyst bed, and the partially combusted gas passes through the reforming catalyst bed before being supplied as the heat exchange medium to the heat exchange steam reformer.

14. A process for using a tube sealing device suitable for a heat exchange reactor, the process comprising the following steps: (a) Supplying process fluid to a heat exchange reactor having a process fluid supply area (11) separated from a heat exchange zone (12) by a first boundary device (14); (b) passing the process fluid from the process fluid supply area through one or more heat exchange tubes (17) extending through the heat exchange zone, wherein the process fluid exchanges heat with a heat exchange medium at a lower pressure than the process fluid passing through the one or more heat exchange tubes in the heat exchange zone. (c) The process fluid is transferred from the heat exchange tube to the process fluid discharge zone (13), which is separated from the heat exchange zone by a second boundary device (15); (d) subjecting the process fluid from the process fluid discharge zone to further processing steps, and (e) passing the resulting treated process fluid as the heat exchange medium through the heat exchange zone (12), wherein each of the one or more heat exchange tubes (17) is fastened to the first boundary device or the second boundary device and engaged with another boundary device by means of a tube sealing device, wherein the tube sealing device comprises a sealing tube (21) fastened to the other boundary device and an inner tube (22) connected to each heat exchange tube and disposed within the sealing tube to provide an overlap area, the inner tube having in the overlap area: (i) a cross-sectional area reduction (ii) a small internal contraction forming a low-pressure region (32), (iii) an expansion region (33) located downstream of the low-pressure region in the flow direction of the process fluid with a cross-sectional area larger than that of the internal contraction, and (iv) one or more channels (34) through the wall of the inner tube connecting the low-pressure region to the outside of the inner tube, wherein the tube sealing device includes one or more grooves (36) arranged to disrupt the flow of gas through the tube sealing device, the one or more grooves (36) being formed in the overlapping region around the inner surface of the sealing tube (21) corresponding to the low-pressure region of the inner tube.

15. The process of claim 14, wherein the heat exchange reactor comprises a heat exchange reformer, the heat exchange reformer comprising the one or more heat exchange tubes (17), the one or more heat exchange tubes being externally heated and containing a steam reforming catalyst (18), the reformer feed passing through the steam reforming catalyst to produce syngas, and wherein the heat exchange medium used to heat the one or more heat exchange tubes is at a lower pressure than the reformer feed.

16. The process of claim 15, wherein the heat exchange reformer is operatively connected to a partial combustion device designed to partially combust the process fluid after it has passed through the one or more heat exchange tubes, and to supply the gas as a heat exchange medium to the heat exchange reformer after the partial combustion.

17. The process of claim 16, wherein the partial combustion apparatus comprises a reforming catalyst bed, and the partially combusted gas passes through the reforming catalyst bed before being supplied as the heat exchange medium to the heat exchange reformer.

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