Reformer furnace with supported reformer tubes

Abstract

The present invention provides a reformer for converting a hydrocarbon feed into a synthesis gas stream. The reformer includes at least one inserted reformer tube, which is at least partially located in a closed volume. The reformer includes a first support member, which is arranged to abut against a second end wall of the reformer to support a second end of the at least one inserted reformer tube.

Description

Technical Field

[0001] The present invention provides a reformer for providing load for an endothermic reaction of converting a hydrocarbon feed into a synthesis gas stream. The reformer includes at least one inserted reformer tube, which is at least partially located in an enclosed volume. The reformer includes a first support member, which is arranged to abut against a second end wall of the reformer to support a second end of the at least one inserted reformer tube. Background Art

[0002] One type of heat exchange reactor currently used in industrial applications is the insert tubular reactor. A conventional insert tubular reactor consists of an inner tube coaxially disposed within an outer jacket tube. Catalyst particles are loaded in an annular space between the inner and outer tube walls. Thus, a process stream of reactants is reacted by passing the process stream through a catalyst that is in a heat conducting relationship with a heat conducting medium flowing externally along the jacket tube wall. When used for endothermic reactions requiring heat, the heat required for the reaction in the process stream is provided by indirect heat exchange with the process stream in the tube. After flowing through the catalyst, the reacted process stream strikes the closed end of the outer tube where the stream flows in reverse to the inner tube of the reactor and is then withdrawn from the reactor as a product stream.

[0003] European Patent Application No. 334540, GB Patent Application No. 2213496 and European Patent Application No. 194067 disclose the use of intercalated tubular reactors in the steam reforming of hydrocarbon process streams.

[0004] Publication US2015 / 0076410 discloses a reformer comprising an inserted reformer tube freely suspended in the reformer. There is no mechanical connection between the closed tube ends of the reformer tube and the bottom of the reformer. This structure is typical because it allows good gas flow from external heating gas around the closed tube ends, thereby allowing good heat transfer to the closed tube ends.

[0005] Insert reformer tubes can be up to 10 or 12 meters in length. Any unevenness in heating, catalyst loading or gas flow during the reforming process may cause undesirable bending or flexing of the reformer tubes. Also, during the reforming process, the reformer tubes can expand longitudinally, which should be taken into account when building the reformer furnace. It would also be beneficial to be able to measure the temperature of the insert reformer tubes, especially at their closed ends. This arrangement also allows for convenient measurement of the process gas temperature at the catalyst bed outlet for process control.

[0006] The technology of the present invention aims to solve at least one of the above problems. SUMMARY OF THE INVENTION

[0008] In a first aspect, the present invention relates to a reformer for converting a hydrocarbon feed into a synthesis gas stream, the reformer having an enclosed volume defined by opposing first and second end walls and at least one side wall extending between the first and second end walls;

[0009] - said reformer furnace comprises at least one inserted reformer tube which is at least partially located within said closed volume,

[0010] - the at least one reformer tube comprises a first end and a second end, the first end and the second end being arranged at opposite ends of the inserted reformer tube along a central axis YY of the inserted reformer tube;

[0011] - wherein a feed gas inlet for said hydrocarbon feed and a process gas outlet for said synthesis gas stream are arranged in said first end portion of said at least one plug-in reformer tube;

[0012] - and wherein said second end of said at least one inserted reformer tube is closed;

[0013] - the reforming furnace further comprises a first support member, the first support member being arranged to abut against a second end wall of the reforming furnace to support the second end portion of the at least one inserted reformer tube to prevent the second end portion (12) of the inserted reformer tube (10) from being displaced relative to the reforming furnace (100) in a direction perpendicular to the central axis YY;

[0014] - wherein the inserted reformer tube (10) extends along a central axis YY, and the first support (60) is arranged to allow the second end (12) of the inserted reformer tube (10) to be displaced relative to the reforming furnace (100) in a direction parallel to the central axis YY during operation.

[0015] Further aspects of the inventive technique are set out in the dependent claims, the drawings and the following description.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The technique is described with reference to the accompanying schematic diagram, in which:

[0018] Figure 1 An inserted reformer tube according to the invention is shown.

[0019] Figure 2 and Figure 3 A variant of the reformer according to the invention is shown. DETAILED DESCRIPTION OF THE INVENTION

[0021] Elements of the reformer and inserted reformer tubes, such as the furnace walls or the ends of the reformer tubes, are described as "first" or "second". All elements of all components denoted as "first" are located at the same end as one another. Typically, the reformer stands on a substantially horizontal surface; in this case, the first end or first end wall is further from the horizontal plane than the second end or end wall.

[0022] Accordingly, there is provided a reformer suitable for converting a hydrocarbon feed into a synthesis gas stream.

[0023] The reforming furnace is usually made of steel, with insulating materials (such as ceramic materials) arranged as needed to maintain the internal temperature while protecting the external structure from excessive temperatures. The flue gas temperature leaving the reforming furnace is usually between 1000-1100°C. The reforming furnace has an enclosed volume defined by opposing first and second end walls and at least one side wall extending between the first and second end walls. The furnace walls are insulated.

[0024] The first and second end walls are usually planar, but may also be curved. There may be four side walls, so that the reformer is usually a rectangular parallelepiped.

[0025] One or more heating elements are located within the enclosed volume of the reforming furnace. Suitably, the heating elements are gas burners. Typically, the heating elements are evenly distributed throughout the enclosed volume of the reforming furnace, so that the furnace is evenly heated throughout the enclosed volume.

[0026] The reformer comprises at least one inserted reformer tube which is at least partially located within the enclosed volume. The inserted reformer tube is generally as described in EP535505, the contents of which are hereby incorporated by reference, and as attached Figure 1 The terms "inserted reformer tube" and "reformer tube" are used interchangeably herein.

[0027] In the steam reforming process, a hydrocarbon and steam stream is catalytically reformed into a product stream of hydrogen and carbon oxides; represented by the following reaction:

[0028] CH4+H2O→CO+3H2 ΔH° 298 =-49.3kcal / mole

[0029] CH4+2H2O→CO2+4H2 ΔH° 298 =-39.4 kcal / mole

[0030] Suitable process conditions (temperature, pressure, flow rates, etc.) and suitable catalysts for such steam reforming processes are known in the art.

[0031] Generally, the plug-in reformer tube comprises an outer tube and an inner tube disposed within the outer tube. A catalyst bed is disposed between the inner tube and the outer tube. The plug-in reformer tube is arranged so that a hydrocarbon feed entering the plug-in reformer tube via a feed gas inlet flows along the outer tube, where the hydrocarbon feed is converted into synthesis gas via the catalyst bed. The synthesis gas thus produced flows along the inner tube and then leaves the plug-in reformer tube through the process gas outlet.

[0032] The steam reforming reaction is initiated by contact with a steam reforming catalyst bed in a tubular heat exchange reactor at a temperature above 350°C. In order to ensure a high conversion of the hydrocarbons, the temperature of the hydrocarbon stream is gradually increased during its passage through the catalyst bed. After passing through the catalyst, the reacted process stream leaves the catalyst at the outlet end of the external reformer tube as a product stream at a temperature between 750°C and 950°C. The heat required for the endothermic reforming reaction carried out in the catalyst is provided by radiation heating the furnace walls. The design of the inserted reformer tube allows for additional heat exchange between the synthesis gas passing through the inner tube (with the catalyst bed) and the gas located in the outer tube.

[0033] The plug-in reformer tube is generally cylindrical, wherein the inner tube and the outer tube have a circular cross-section about a central axis YY. The reformer tube extends between a first end and a second end. The reformer tube includes a first end and a second end, wherein the first end and the second end are arranged at opposite ends of the plug-in reformer tube along the central axis YY of the plug-in reformer tube. The first end is a portion of the reformer tube extending from the first end to the second end, and the second end is a portion of the reformer tube extending from the second end to the first end. The first and second ends do not overlap and independently extend from their respective first and second ends a distance less than 30%, such as less than 20%, such as less than 10% of the entire length of the plug-in reformer tube.

[0034] A feed gas inlet for the hydrocarbon feed and a process gas outlet for the synthesis gas stream are arranged at a first end of the plug-in reformer tube, i.e. at the same end. The second end of the plug-in reformer tube is closed, so that the gas flowing along the outer tube returns to the process gas outlet via the inner tube. The closed second end of at least one plug-in reformer tube is arranged in the closed volume of the reforming furnace so that the entire reformer tube is heated to the desired level.

[0035] like Figure 2 and Figure 3As shown, the reformer also includes a first support member, which is arranged to abut against the second end wall of the reformer to support the second end of at least one inserted reformer tube. Suitably, the first support member is arranged to abut against the second end wall of the reformer to support the second end of at least one inserted reformer tube. In this way, undesirable bending or flexing of the reformer tube along its length can be reduced. In addition, the first support member can be designed to provide a mechanism that can be used for the second end of the inserted reformer, such as a thermocouple or other temperature measurement device.

[0036] Since the reformer operates at high temperatures, its elements will expand under the reforming process conditions. The expansion of the inserted reformer tube is mainly carried out along its longitudinal axis YY. At the same time, it is still important to reduce the bending or deflection of the reformer tube. Therefore, the first support is arranged to allow the second end of the inserted reformer tube to be displaced relative to the reformer in a direction parallel to said central axis YY and - at the same time - prevent the second end of the inserted reformer tube from being displaced relative to the reformer in a direction perpendicular to said central axis YY.

[0037] This function can be achieved, for example, if the second end wall of the reformer comprises an opening in which the first support is located, so that the first support is located within the second end wall of the reformer. A flexible seal is provided in the opening, which prevents hot gases from leaving the reformer while allowing the first support to be displaced relative to the reformer in a direction perpendicular to said central axis YY.

[0038] The feed gas inlet for hydrocarbon feed and the process gas outlet for synthesis gas flow of each inserted reformer tube are arranged outside the closed volume of the reformer. This simplifies the structure and allows easy use of the inlet / outlet without entering the interior of the reformer. In this structure, the first end wall of the reformer includes an opening with a seal, and at least one inserted reformer tube passes through the seal. In addition, the reformer also appropriately includes a second support member, which is arranged to support the first end of the inserted reformer tube at least in the direction of the central axis YY of the inserted reformer tube, and the second support member is arranged outside the closed volume of the reformer. This structure also allows the inserted reformer tube to be removed from the reformer or inserted into the reformer by passing it through the opening in the first end wall of the reformer. The inserted reformer tube can be raised or lowered by the second support member.

[0039] In a preferred aspect, the reformer - and preferably its second end wall - comprises at least one closed sleeve extending into the enclosed volume. The closed sleeve is closed at its first end and open at its lower end. The closed sleeve is arranged to allow a temperature measuring device (such as a thermocouple) to be inserted into the enclosed volume of the reformer. This allows the internal temperature of the reformer to be measured at a desired location. In a particularly preferred aspect, such as Figure 3As shown, the closed end of the closure sleeve extends to the closed end of the second end of at least one inserted reformer tube. This structure allows the temperature of the second end of the inserted reformer tube to be measured, which is possible in known structures. Figure 3 As shown, a closing sleeve may be included in said first support member, such that the closing sleeve provides a dual function.

[0040] Specific aspects of the construction of the first support are provided. In one aspect, the first support extends from the second end of the inserted reformer tube in the direction of its central axis YY to the second end wall of the reformer furnace. In fact, such a first support is an extension of the reformer tube along the YY axis. This structure allows maximum support for the reformer tube, and also means that the reformer tube and the first support can be manufactured as one piece. In another aspect, the first support has a cylindrical shape around the central axis XX, and is arranged so that the central axis XX is an extension of the central axis YY of the inserted reformer tube. In another aspect, the radius of the cylindrical first support around its central axis XX is substantially the same as the radius of the inserted reformer tube around its central axis YY. Similarly, this allows the reformer tube and the first support to be easily constructed as one piece, and also allows both the reformer tube and the first support to be inserted and removed from the reformer furnace via the opening of the first end wall of the reformer furnace.

[0041] Detailed description of the drawings

[0042] Figure 1 A plug-in reformer tube 10 is shown with an outer tube 14, within which an inner tube 15 is disposed. A catalyst bed 16 is disposed between the inner tube 15 and the outer tube 14. The plug-in reformer tube 10 is arranged such that a hydrocarbon feed 201 enters the plug-in reformer tube 10 via the feed gas inlet 11 ', flows along the outer tube 14, and is converted into synthesis gas in the outer tube 14 via the catalyst bed 16. The second end 12 of the plug-in reformer tube 10 is closed. Thus, at the second end 12 of the reformer tube 10, the gas flow direction is reversed, so that the synthesis gas 202 flows along the inner tube 15 and then leaves the plug-in reformer tube 10 via the process gas outlet 11". During the flow of the hot synthesis gas along the inner tube 15, the hot synthesis gas transfers heat to the catalyst bed 16. The reformer tube 10 has a first end 11 and a second end 12, which are disposed at opposite ends of the plug-in reformer tube 10 along the central axis YY of the plug-in reformer tube 10.

[0043] Figure 2 A reformer furnace 100 is shown including an inserted reformer tube 10, the details of which are shown in FIG. Figure 1 For clarity, Figure 2Not all details of the reformer tube 10 are shown in the figure. The reformer 100 has a closed volume 100a defined by opposite first and second end walls 101, 102 and at least one side wall 103 extending between the first and second end walls 101, 102. In this case, the reformer 100 includes a first support 60 that abuts against the second end wall 102 to support the second end 12 of the inserted reformer tube 10.

[0044] As shown, a feed gas inlet 11' for a hydrocarbon feed 201 and a process gas outlet 11" for a synthesis gas stream 202 are arranged outside the closed volume 100a of the reformer 100. The first end wall 101 of the reformer 100 comprises an opening 101a with a seal 101b through which at least one inserted reformer tube 10 passes. A second support 50 is shown which can support the first end 11 in the direction of the central axis YY. A closed sleeve 105 extends into the closed volume 100a and allows the insertion of a temperature measuring device.

[0045] Figure 3 Shows the Figure 2 A similar reforming furnace 100. Figure 3 In the embodiment of the present invention, the closed end of the closing sleeve 105 extends to the closed end of the second end portion 12 of the at least one inserted reformer tube 10 .

[0046] The invention has been described with reference to a number of aspects and embodiments. These aspects and embodiments may be combined as desired by one skilled in the art while still falling within the scope of the claims.

Claims

1. A reformer (100) for converting a hydrocarbon feed (201) into a synthesis gas stream (202), the reformer (100) having a closed volume (100a) defined by opposing first and second end walls (101, 102) and at least one side wall (103) extending between the first and second end walls (101, 102); - the reformer furnace (100) comprises at least one inserted reformer tube (10) which is at least partially located within the closed volume (100a), - the at least one reformer tube (10) comprises a first end (11) and a second end (12), the first end (11) and the second end (12) being arranged at opposite ends of the at least one reformer tube (10) along a central axis YY of the at least one reformer tube (10); - wherein a feed gas inlet (11') for the hydrocarbon feed (201) and a process gas outlet (11") for the synthesis gas stream (202) are arranged in the first end (11) of the at least one inserted reformer tube (10); - and wherein said second end (12) of said at least one inserted reformer tube (10) is closed; - the reforming furnace (100) further comprises a first support member (60), the first support member (60) being arranged to support the second end portion (12) of the at least one inserted reformer tube (10) against a second end wall (102) of the reforming furnace (100) to prevent the second end portion (12) of the inserted reformer tube (10) from being displaced relative to the reforming furnace (100) in a direction perpendicular to the central axis YY; wherein the inserted reformer tube (10) extends along a central axis YY, and the first support (60) is arranged to allow the second end (12) of the inserted reformer tube (10) to be displaced relative to the reforming furnace (100) in a direction parallel to the central axis YY during operation wherein the closed second end (12) of the at least one inserted reformer tube (10) is disposed within a closed volume (100a) of a reforming furnace (100); The second end wall (102) of the reforming furnace (100) includes an opening where the first support member (60) is located.

2. A reformer (100) according to claim 1, wherein a feed gas inlet (11') for the hydrocarbon feed (201) and a process gas outlet (11") for the synthesis gas flow (202) of the at least one inserted reformer tube (10) are arranged outside the closed volume (100a) of the reformer (100), and wherein a first end wall (101) of the reformer (100) includes an opening (101a) having a seal (101b), through which at least one inserted reformer tube (10) passes.

3. The reformer (100) according to any one of the preceding claims, further comprising a second support member (50), the second support member (50) being configured to support the first end (11) of the at least one inserted reformer tube (10) at least in the central axis YY direction of the at least one inserted reformer tube (10), the second support member (50) being disposed outside the closed volume (100a) of the reformer (100).

4. The reforming furnace (100) according to claim 1 or 2, wherein the first support member (60) is included in the second end wall (102) of the reforming furnace (100).

5. The reforming furnace (100) according to claim 1 or 2, wherein the second end wall (102) of the reforming furnace (100) includes at least one closed sleeve (105) extending into the closed volume (100a), and the closed sleeve (105) is configured to allow a temperature measuring device to be inserted into the closed volume (100a) of the reforming furnace (100).

6. The reforming furnace according to claim 5, wherein said at least one closing sleeve (105) is contained in said first support (60).

7. The reformer furnace (100) according to claim 6, wherein the closed end of the closing sleeve (105) extends into the closed end of the second end portion (12) of the at least one inserted reformer tube (10).

8. The reforming furnace (100) according to claim 1 or 2, wherein the first support member (60) extends from the second end portion (12) of the inserted reformer tube (10) along the direction of its central axis YY to the second end wall (102) of the reforming furnace (100).

9. The reformer furnace (100) according to claim 8, wherein the first support (60) has a cylindrical shape around the central axis XX of the inserted reformer tube (10), and is arranged so that the central axis XX is an extension of the central axis YY of the inserted reformer tube (10).

10. The reformer (100) according to claim 9, wherein the radius of the cylindrical first support (60) around the central axis XX of the inserted reformer tube (10) is substantially the same as the radius around the central axis YY of the inserted reformer tube (10).

11. The reformer (100) according to claim 1 or 2, wherein the inserted reformer tube (10) comprises an outer tube (14), an inner tube (15) arranged inside the outer tube (14), and a catalyst bed (16) arranged between the inner tube (15) and the outer tube (14); the inserted reformer tube (10) is arranged so that a hydrocarbon feed (201) enters the inserted reformer tube (10) via the feed gas inlet (11'), flows along the outer tube (14), and in the outer tube (14) the hydrocarbon feed is converted into synthesis gas via the catalyst bed (16); wherein the synthesis gas flow (202) flows along the inner tube (15) and then leaves the inserted reformer tube (10) via the process gas outlet (11").

Images