Method for preventing metal dusting in gas heating reforming device

Abstract

The present specification describes a gas heating reformer comprising: one or more tubes containing a steam reforming catalyst; and a housing surrounding the tube and defining a housing side with the tube; wherein the housing comprises an inlet and an outlet for a heat exchange medium; wherein the shell side is provided with a water gas shift catalyst at one or more zones of the shell side in which the heat exchange medium in contact with the shell side during use has a temperature of 500 DEG C to 750 DEG C. Also described is an apparatus for producing hydrogen, ammonia or methanol comprising a gas heated reformer. The water gas shift catalyst may be retrofitted to an existing gas heater reformer.

Description

Technical Field

[0001] The present invention relates to the reforming of hydrocarbons in a gas heated reformer, for example, the steam reforming of natural gas. Background Art

[0002] In steam reforming, a process gas containing a mixture of hydrocarbon feedstock and steam and in some cases carbon dioxide passes through a catalyst-filled heat exchange tube at high pressure, and the heat exchange tube is externally heated by means of a suitable heat exchange medium (usually a hot gas mixture). The heat exchange medium can be a burning hydrocarbon fuel, flue gas, or a process gas that has passed through a tube but has been further treated before being used as a heat exchange medium. For example, GB 1578270 describes a method in which a primary reforming gas is subjected to partial oxidation, wherein it is partially burned together with oxygen or air, and then passed through a secondary reforming catalyst bed (the method is called secondary reforming) in some cases. The partially burned gas obtained (the term includes secondary reforming gas) is then used as a heat exchange medium and is passed into the shell side of a primary reformer to heat the tube. In the case where the secondary reforming gas is used as a heat exchange medium, it generally contains methane, hydrogen, carbon oxides, steam, and any gas (such as nitrogen) that is present in the feed and is inert under the conditions adopted. If flue gas is used as a heat exchange medium, a large amount of carbon oxides, steam, and inert gases are generally contained.

[0003] Heat exchange reformers are usually made of materials containing iron and nickel. Under some conditions, undesirable side reactions may occur on the shell side of the heat exchange reformer. These reactions are promoted by the nickel and / or iron in the material, particularly on the heat exchange tubes. Undesirable side reactions include methanation and carburization reactions. These reactions are caused directly or indirectly by the catalytic interaction between the metal present in the material forming the shell side and the carbon monoxide (CO) and / or methane present in the heat exchange medium. In the steam reforming of the primary reformer in which the heat exchange medium is a primary reforming gas that has been subjected to further treatment, the problem is exacerbated because people expect to operate at a low steam to hydrocarbon ratio for economic reasons, which leads to an increase in the reduction potential of the gas, as evidenced by the increase in CO concentration.

[0004] Methanation is the conversion of carbon oxides to methane and water, i.e. in the case of CO methanation, the reverse reaction of steam reforming and is promoted, for example, by nickel. The CO reaction is described as follows:

[0005] CO + 3H2 → CH4 + H2O (Reaction 1)

[0006] The water gas shift (WGS) reaction is the reaction of carbon monoxide with steam to produce carbon dioxide and hydrogen, and is promoted, for example, by iron. The reaction is described as follows:

[0007] CO + H2O → CO2 + H2 (Reaction 2)

[0008] Carburization is believed to be caused by the interaction of carbon deposits with the metal in the reactor tubes. The deposited carbon can be caused by CO reduction, CO disproportionation, and hydrocarbon cracking reactions. These reactions occur on the metal surface and can be catalyzed by Fe, Ni, or Cr. The carbon formation reaction is described as follows:

[0009] Reduction: CO + H2 → C + H2O (Reaction 3)

[0010] Disproportionation: 2CO→C+CO2 (Reaction 4)

[0011] Cracking: CH4→C+2H2 (Reaction 5)

[0012] Carburization of the material is also known as "metal dusting" and leads to corrosion of the metal surface, which can lead to failure of the reformer tubes, for example. An increase in the methane level in the process gas can also occur via hydrogenation of deposited carbon.

[0013] Because process efficiency and corrosion are affected by carbon monoxide reactions, it is desirable to reduce the interaction between carbon monoxide (CO) present in the heat exchange medium and the metal on the shell side of the reformer.

[0014] One method of preventing shell side corrosion is to include additives in the inlet gas. Examples of additives include sulfur containing compounds (WO00 / 09441 (ICI)), mixtures of sulfur containing compounds and phosphorus containing compounds (WO01 / 66806 (Kalina)), or compounds containing at least one atom selected from phosphorus, tin, antimony, arsenic, lead, bismuth, copper, germanium, silver or gold (WO03 / 051771 (Johnson Matthey)).

[0015] Another approach is to use corrosion-resistant materials on the shell side, as described, for example, in HJ Grabke, Research Disclosure, 37031, 1995 / 69. However, this approach is expensive and cannot be retrofitted to existing reactors.

[0016] Another method of passivating a metal surface is to apply a coating. For example, US2011 / 305605 (BASF) describes a method for protecting a metal surface from chemical attack at high temperatures by applying a layer-forming composition comprising nanoscale powder, porous ceramic powder and solvent to the metal surface to be protected and curing the layer-forming composition. The resulting layer is porous, has a very large internal surface, and can decompose impurities without the need for a catalyst.

[0017] Another approach is to use ceramic tubes in the reformer, as described in WO 2013 / 182425 (Casale).

[0018] Alternative ways are needed to avoid methanation and metal dusting on the shell side of a gas heated reformer. It would be desirable to find a solution that could be retrofitted to existing gas heated reformers without requiring complete replacement of the tubes within the gas heated reformer. Summary of the invention

[0019] The inventors have found that including a water gas shift (WGS) catalyst on the shell side of a gas heated reformer solves the above problems and also provides many other benefits. As used herein, the term "gas heated reformer" refers to a device having one or more tubes and a shell surrounding the tubes. The inner surface of the tubes defines the tube side. The outer surface of the tube and the inner surface of the shell together define the shell side. Gas heated reformers are sometimes referred to as heat exchange reformers in the literature.

[0020] As previously described, metal dusting can be caused in part by the decomposition of CO to carbon on the shell side (Reactions 3 and 4). These reactions can be reduced by including a WGS catalyst to promote the reaction of CO and steam via the WGS reaction on the shell side of the reformer (Reaction 2). If the gas has a positive thermodynamic driving force for the water gas shift, the concentration of CO is reduced by the WGS catalyst and metal dusting is reduced or avoided. Another benefit is that because the WGS reaction is exothermic, it can be used to help drive the endothermic steam reforming reaction that occurs in the tubes of the gas heated reformer. Although it is known to operate a water gas shift unit downstream of a gas heated reformer, to the best of the inventors' knowledge, it has not been previously considered to include a WGS catalyst on the shell side of the reformer to prevent metal dusting.

[0021] GB2179366A describes a method for producing synthesis gas using an arrangement comprising a primary reactor and a secondary reformer as an exchange reactor; the effluent of the secondary reformer is passed into a primary reforming zone within the primary reactor as an indirect heating medium for the exchange reactor. In a preferred embodiment, a carbon monoxide shift catalyst is provided on the shell side of the exchange reactor. The advantage of using this arrangement is that when the gas from the secondary reformer is cooled, reaction 2 proceeds to the right hand side to maintain chemical equilibrium, thereby providing heat to the colder end of the exchanger. The reference does not describe or recognize the benefits of using a properly positioned WGS catalyst to prevent metal dusting.

[0022] In a first aspect, the present invention relates to a gas heating reforming device, the gas heating reforming device comprising:

[0023] one or more tubes containing a steam reforming catalyst; and

[0024] a housing surrounding the tube and defining a shell side together with the tube;

[0025] wherein the housing includes an inlet and an outlet for a heat exchange medium; and

[0026] The shell side is provided with a water-gas shift catalyst at one or more regions of the shell side in which the heat exchange medium in contact with the shell side during use has a temperature of 500°C to 750°C.

[0027] The gas heated reformer may be a component of a plant for producing hydrogen, ammonia or methanol.

[0028] In a second aspect, the present invention relates to an apparatus for producing hydrogen, ammonia or methanol, the apparatus comprising a gas heated reformer according to the first aspect.

[0029] In a third aspect, the invention relates to a method carried out in a gas heated reformer according to the first aspect, the method comprising the steps of:

[0030] providing a heat exchange medium comprising syngas to an inlet on the shell side; and

[0031] Water gas shift is performed on the shell side.

[0032] In a fourth aspect, the invention relates to a method for retrofitting a gas heated reformer comprising one or more tubes and a shell surrounding the tubes and defining a shell side together with the tubes, wherein the shell comprises an inlet and an outlet for a heat exchange medium;

[0033] The method comprises the step of providing a water gas shift catalyst to the shell side at one or more regions of the shell side where the heat exchange medium in contact with the shell side during use has a temperature of 500°C to 750°C.

[0034] The converted gas heated reformer is a reformer according to the first aspect.

[0035] In a fifth aspect, the present invention relates to the use of a water-gas shift catalyst on the shell side of a gas heated reformer according to the first aspect for preventing metal dusting. DETAILED DESCRIPTION

[0036] Any sub-headings are included for convenience only and are not intended to limit the disclosure in any way.

[0037] Gas heated reformer

[0038] In a conventional gas heated reformer, a process fluid (usually a mixture comprising hydrocarbons and steam) passes from a process fluid feed zone through heat exchange tubes containing a steam reforming catalyst. The heat exchange tubes (hereinafter referred to as "tubes") are arranged in a heat exchange zone defined by a shell through which a heat exchange medium passes and then enters a process fluid discharge zone. The heat exchange medium flows through the shell around the outside of the heat exchange tubes. This type of heat exchange reformer is described in GB1578270 (Pullman Inc) and WO97 / 05947 (ICI).

[0039] The "tube side" of such a reforming device is understood to include all surfaces within the tubes of the device. The volume defined by the tube side is referred to herein as the "tube side volume". The tubes of the gas heated reformer contain steam reforming catalyst. Although the steam reforming catalyst can be contained on the inner surface of the tube as a coating, it is preferred that the catalyst is located in the tube side volume rather than being present on the inner surface of the tube as a coating. For example, the tube side volume may include one or more catalyst beds, which contain steam reforming catalyst. Alternatively, the tube side volume may include one or more structures, which are coated with steam reforming catalyst. Such structured catalysts are described, for example, in WO2012 / 103432 and WO2013 / 151885 (Johnson Matthey) and can be used as CATACEL TM The technology is commercially available from Johnson Matthey.

[0040] The "shell side" of such a reformer is understood to include all surfaces within the shell of the device that are exposed to the heat exchange medium. Such surfaces include the inner surface of the shell that defines the heat exchange zone, the outer surfaces of the tubes, the outer surfaces of any fins attached to the tubes to increase their heat transfer area, the surfaces of any jackets surrounding the heat exchange tubes, the surfaces of any tube sheets that define the boundaries of the heat exchange zone and are exposed to the heat exchange medium, and the outer surfaces of any header tubes within the heat exchange zone. The volume defined by the shell side is referred to herein as the "shell side volume."

[0041] In the present invention, the shell side is provided with a WGS catalyst located at one or more regions of the shell side where the heat exchange medium in contact with the shell side during use has a temperature of 500°C-750°C. A variety of WGS catalysts can be used in the present invention. The WGS catalyst is selected because it can promote the WGS reaction without promoting the methanogenic reaction. The WGS catalyst must be compatible with the temperature of the heat exchange medium at the region of the shell side that is susceptible to metal dusting. Typically, the region susceptible to metal dusting is those regions where the temperature of the heat exchange medium is 500°C-750°C. Below 500°C, the carbon formation reaction is kinetically slow. Above 750°C, carbon formation is thermodynamically unfavorable / impossible. The location where the temperature of the heat exchange medium in contact with the shell side is 500°C-750°C can be predetermined by simulation. Suitable WGS catalysts capable of operating under these conditions are variously referred to in the art as "high temperature shift" or "ultra-high temperature shift" catalysts. A variety of WGS catalysts capable of operating at these temperatures are known in the art, and a skilled person will be able to select a suitable catalyst given the temperature and pressure of the heat exchange medium. In some embodiments, the WGS catalyst is located only on the shell side in areas where the heat exchange medium in contact with the shell side during use has a temperature of 500° C. to 750° C. For the avoidance of doubt, the WGS catalyst may be located on all shell side surfaces having a temperature of 500° C. to 750° C. during use, or only on a portion thereof.

[0042] Examples of "high temperature" WGS catalysts that can operate at temperatures between 400°C and 750°C are described in EP1149799A1 (Haldor Topsoe A / S), the contents of which are incorporated herein by reference. Suitable catalysts include those containing Mg, Mn, Al, Zr, La, Ce, Pr and Nd that are capable of forming basic oxides.

[0043] Examples of "ultra-high" temperature shift catalysts that can operate at temperatures between 450°C and 900°C are described in WO 2010 / 135297 A1 (Air Liquide), the contents of which are incorporated herein by reference. The catalysts are partially reducible transition metal oxides such as oxides of cerium, neodymium, praseodymium, gadolinium and manganese.

[0044] Other examples of "ultra-high" temperature shift catalysts that can operate at temperatures between 450°C and 900°C are described in US 2009 / 0232728 A1 (Sud-Chemie Inc), the contents of which are incorporated herein by reference. The catalyst is deposited on a surface area of ​​30 m 2 / g-200m 2 / g of rhenium on the carrier.

[0045] In a preferred embodiment, the WGS catalyst is provided as a coating on the outer surface of the tube. One benefit of this arrangement is that it can be retrofitted to an existing gas heated reformer by applying the coating on the existing tubes, which can provide cost savings compared to fitting new tubes with a WGS catalyst coating. Another benefit of this arrangement is that the coating provides a physical barrier between the tubes and the heat exchange medium, which also helps prevent metal dusting. The coating can be a continuous coating or can be a partial coating on a portion of the outer surface of the tube. In order to reduce unnecessary costs, the coating is preferably a partial coating located at the portion of the shell side that is most susceptible to dust, taking into account the temperature and gas composition of the entire shell side.

[0046] Alternatively, the WGS catalyst may be provided in the shell side volume, rather than being applied as a coating on the outer surface of the tube. For example, as a bed of formed catalyst particles (e.g., pellets). Alternatively, as a structured catalyst, the structured catalyst may be in the form of a metal or ceramic monolith, or in the form of a folded metal or ceramic structure, in each case coated with a water gas shift catalyst. Such structured catalysts are described, for example, in WO2012 / 103432 and WO2013 / 151885 (Johnson Matthey), and may be used as CATACEL TM The technology is commercially available from Johnson Matthey.

[0047] In a preferred embodiment, the tubes of the gas heated reformer are at least partially made of steel, nickel-containing steel or nickel-based alloys. As used herein, the term "steel" refers to an iron-based alloy containing iron as the single largest component and also including carbon. The steel used to make the tubes for the gas heated reformer generally also contains nickel, i.e., is a nickel-containing steel. Alternative materials for the tubes of the gas heated reformer include nickel-based alloys containing nickel as the single largest component, such as Preferably, at least a portion of the outer surface of the tube is made of steel, nickel-containing steel or a nickel-based alloy. Nickel steel and nickel-based alloys are designed to minimize metal dusting reactions, but can be expensive. Another benefit of the present invention is that it can expand the number of materials that can be used for gas heated reformer tubes and can allow the use of cheaper materials.

[0048] The gas heated reformer is typically a component of an apparatus for producing synthesis gas. The synthesis gas can be used in downstream processes (e.g., for hydrogen, methanol, or ammonia production). It will be appreciated that the extent of the water gas shift on the shell side will be more targeted where the gas heated reformer is a component of an apparatus for producing hydrogen or ammonia than where the gas heated reformer is a component of an apparatus for producing methanol. Where the gas heated reformer is a component of an apparatus for producing hydrogen or ammonia, it is less important to control the extent of the WGS on the shell side since the apparatus will typically include multiple steps downstream of the gas heated reformer to maximize hydrogen production.

[0049] The invention also relates to a plant for producing hydrogen, ammonia or methanol, comprising a gas heated reformer according to the first aspect.

[0050] In a preferred embodiment, the apparatus comprises a gas heated reformer and an autothermal reformer arranged in series and arranged so that part of the reformed gas from the autothermal reformer is fed to the shell side of the gas heated reformer to provide heat for the reforming reaction occurring on the tube side of the gas heated reformer.

[0051] method

[0052] The invention also relates to a steam reforming method using the device according to the first aspect.

[0053] The process of the present invention is particularly useful for catalytic steam reforming units for steam reforming of hydrocarbons. In a typical process, a mixture comprising a hydrocarbon feedstock and steam and, in some cases, carbon dioxide or other components is passed under high pressure through catalyst-filled heat exchange tubes that are externally heated to a maximum temperature in the range of 700°C to 900°C by means of a suitable heat exchange medium (typically a hot gas mixture) to form a primary reforming gas. Catalysts for performing primary reforming include shaped units, such as cylinders, rings, saddles, and cylinders having a plurality of through holes, and are typically formed of a refractory support material, such as alumina, calcium aluminate cement, magnesium oxide, or zirconium oxide impregnated with a suitable catalytically active material, typically nickel and / or ruthenium. Examples of commercial reforming catalysts include KATALCO available from Johnson Matthey. TM Steam Reforming Catalysts. Structured catalysts can also be used in reformer tubes.

[0054] The hydrocarbon feedstock may comprise any gaseous or low boiling hydrocarbon feedstock, such as natural gas. It is preferably methane or natural gas containing a substantial proportion of methane (e.g. more than 90% v / v of methane). The feedstock is preferably compressed to a pressure in the range of 20 bar to 80 bar absolute.

[0055] The method and apparatus of the present invention are different from conventional heat exchange reforming apparatuses in that a WGS catalyst is present on the shell side. As mentioned above, the function of the WGS catalyst is to reduce the CO concentration on the shell side, thereby reducing or preventing metal dusting and methanation.

[0056] The heat exchange medium fed to the shell side is synthesis gas, which refers to a gas containing CO and H2. Preferably, the heat exchange medium is a primary reformed gas (formed in the tubes of the gas heated reformer) that has been subjected to further processing, in which case it will also include steam, CO2 and low levels of CH4. In a preferred embodiment, the heat exchange medium is a primary reformed gas that has undergone a further processing step leaving the process fluid discharge zone. The further processing step is typically partial combustion with an oxygen-containing gas (e.g., air, oxygen-enriched air or oxygen). Preferably, before being used as a heat exchange medium, the partially burned primary reformed gas passes through a secondary reforming catalyst bed to achieve further reforming (e.g., secondary reforming).

[0057] Preferably, the conversion of hydrocarbons is substantially completed before the reformed synthesis gas (heat exchange medium) is fed to the shell-side inlet of the gas-heated reformer. Typically, the synthesis gas fed to the shell-side inlet of the gas-heated reformer has a methane content of less than 10% by volume, preferably less than 5% by volume, for example less than 2% by volume.

[0058] The reformed synthesis gas (heat exchange medium) is fed to the shell side inlet of the gas heated reformer. Typically, the gas entering the inlet has a temperature of 700°C or higher.

[0059] The pressure of the heat exchange medium fed to the shell-side inlet is generally from 20 bar to 80 bar absolute, preferably from 20 bar to 55 bar absolute, more preferably from 20 bar to 45 bar absolute.

[0060] The heat exchange medium contacts the WGS catalyst on the shell side to convert CO and steam present in the heat exchange medium into CO2 and H2. The heat exchange medium at the shell side outlet has a reduced CO concentration compared to the heat exchange medium at the shell side inlet.

[0061] The shell side outlet may require further downstream processing to achieve an acceptable H2 yield. Typically, a WGS unit is present downstream of the shell side outlet. Those skilled in the art will know the design of a suitable WGS unit.

[0062] The shell side outlet (optionally having undergone further reaction to increase H 2 yield) can be treated downstream to remove contaminants (CO 2 , hydrocarbons, etc.).

[0063] Modification method

[0064] One advantage of the present invention is that the WGS catalyst can be retrofitted into the shell side of an existing reformer during reactor shutdown. The existing unit comprises one or more tubes and a shell surrounding the tubes and defining the shell side together with the tubes, wherein the shell comprises an inlet and an outlet for a heat exchange medium.

[0065] The method comprises the step of providing a water gas shift catalyst to the shell side. The resulting reformer may be as described in the first aspect. The arrangement and type of water gas shift catalyst may be as described under the heading "Gas heated reformer". Features described as preferred under the heading "Gas heated reformer" also apply to the retrofitted device.

[0066] In one embodiment, the method involves applying a water gas shift catalyst coating on one or more existing tubes.A benefit of this method is that it does not require replacement of the reformer tubes and is a relatively cost effective way to upgrade existing reformers.

[0067] In one embodiment, the method involves replacing one or more tubes with tubes having a water gas shift catalyst applied to their outer surface. This may be appropriate where the tubes are nearing the end of their useful life and require replacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Reference Figure 1 To further describe the present invention, Figure 1 A process flow diagram incorporating one embodiment of the present invention is depicted.

[0069] refer to Figure 1, natural gas under high pressure (usually in the range of 15 bar to 50 bar absolute pressure) is fed via pipeline 10 and mixed with a small amount of hydrogen-containing gas fed via pipeline 12. The mixture is then heated in heat exchanger 14 and fed to desulfurization stage 16, where the gas mixture is contacted with a bed of hydrodesulfurization catalyst (such as nickel molybdate or cobalt molybdate) and absorbent (such as zinc oxide) to form hydrogen sulfide by hydrodesulfurization. The desulfurized gas mixture is then fed to saturator 20 via pipeline 18, where the gas is contacted with a hot water stream supplied via pipeline 22. Saturated gas leaves saturator via pipeline 24 and can undergo a low temperature adiabatic reforming step if necessary. If necessary, saturated gas can be mixed with recycled carbon dioxide supplied via pipeline 26, and then heated to the desired heat exchange reformer inlet temperature in heat exchanger 28. The heated process gas is then fed into the catalyst-containing tube of heat exchange reformer 32 via pipeline 30. The heat exchange reformer has a process fluid feed zone 34, a heat exchange zone 36, a process fluid discharge zone 38, and a first boundary device 40 and a second boundary device 42 that separate the zones from each other. The process fluid is subjected to steam reforming in a plurality of heat exchange tubes 44 containing a steam reforming catalyst to produce a primary reformed gas stream. Only four tubes are shown; those skilled in the art will well understand that in practice, there may be tens or hundreds of such tubes. The primary reformed gas stream is then passed from the heat exchange tubes 44 into the process fluid discharge zone 38 and thence further processed via line 46. This further processing includes partial combustion with an oxygen-containing gas supplied via line 48 in a vessel containing a bed of a secondary reforming catalyst 50 (e.g., nickel supported on calcium aluminate or alumina). The resulting secondary reformed gas is passed into the heat exchange zone 36 via line 52 as a heat exchange medium. The heat exchange medium passes upward through the spaces between the heat exchange tubes, thereby supplying the heat required for primary reforming. A water gas shift catalyst 37 is included in the heat exchange zone to carry out the water gas shift reaction. The shifted gas leaves the reactor via line 56.

[0070] Figure 2 The outlet concentrations of CO, CO 2 , and CH 4 generated in Comparative Example 1 are shown.

[0071] Figure 3 The outlet concentrations of CO, CO2 and CH4 produced in Example 2 are shown.

[0072] Example

[0073] Example 1 (Comparative)

[0074] The diameter of 3mm The rod (i.e. Ni-Fe-Cr alloy with C, Al and Ti additions) was cut into semicircular pieces and placed in the reaction vessel. A total of 73 pellets were loaded to a total mass of 10.9 g and a surface area of ​​about 2400 mm 2 The reactor was filled with 20% molten metal and 10% molten metal. The reactor was pretreated in H2 at 615°C for 24 hours before the process gas was introduced to remove any protective oxide layer from the surface of the material, thereby accelerating the time taken to initiate metal dusting. The process gas having the composition shown in Table 1 was introduced into the reactor. The outlet concentrations of CO, CO2 and CH4 were measured and are shown in Figure 2 The outlet concentration of methane increased steadily during the experiment.

[0075]

[0076] Table 1.

[0077] Example 2

[0078] The process of Example 1 was followed except that The rods were replaced with CATACEL from Johnson Matthey after being cut into semicircular pieces. TM Materials (water gas shift catalyst) The outlet concentrations of CO, CO2 and CH4 were measured and shown in Figure 3 The outlet concentration of methane remained low during the experiment.

Claims

1. A gas heating reforming device, comprising: one or more tubes, the one or more tubes containing a steam reforming catalyst; and a housing surrounding the tube and defining a shell side together with the tube; wherein the housing includes an inlet and an outlet for a heat exchange medium; Wherein the shell side is provided with a water gas shift catalyst located at one or more regions of the shell side in which the heat exchange medium in contact with the shell side during use has a temperature of 500°C - 750°C.

2. The device according to claim 1, wherein the water-gas shift catalyst is located only in the region of the shell side in which the heat exchange medium in contact with the shell side during use has a temperature of 500°C - 750°C.

3. An apparatus according to claim 1 or claim 2, wherein the steam reforming catalyst is located within the tube side volume.

4. The apparatus of claim 3, wherein the tube side volume comprises one or more catalyst beds comprising a steam reforming catalyst.

5. The apparatus of claim 3, wherein the tube side volume comprises one or more structures coated with a steam reforming catalyst.

6. The device according to any one of claims 1 to 5, wherein the tube is at least partially made of steel, nickel-containing steel or a nickel-based alloy.

7. The apparatus according to any one of claims 1 to 6, wherein the water-gas shift catalyst is provided as a coating on the outer surface of the tube.

8. An apparatus for producing hydrogen, ammonia or methanol, the apparatus comprising a gas heating reformer according to any one of claims 1 to 7.

9. The apparatus according to claim 8 comprises a gas heated reformer and an autothermal reformer arranged in series, and is arranged so that part of the reformed gas from the autothermal reformer is fed to the shell side of the gas heated reformer to provide heating for the reforming reaction occurring on the tube side of the gas heated reformer.

10. A steam reforming method carried out in a heat exchange reforming device according to any one of claims 1 to 7, the steam reforming method comprising the following steps: providing a heat exchange medium comprising syngas to the inlet of the shell side; as well as A water-gas shift is performed on the shell side.

11. The process according to claim 10, wherein the synthesis gas fed to the inlet of the shell side has a methane content of less than 10% by volume.

12. The method of claim 10, wherein the synthesis gas fed to the inlet of the shell side has a methane content of less than 5% by volume.

13. The method according to any one of claims 10 to 12, wherein the temperature of the heat exchange medium fed to the inlet of the shell side is 700°C or higher.

14. The process according to any one of claims 10 to 13, wherein the pressure of the heat exchange medium fed to the inlet is from 20 bar to 80 bar absolute.

15. The process according to any one of claims 10 to 13, wherein the pressure of the heat exchange medium fed to the inlet is from 20 bara to 55 bara.

16. A method for retrofitting a gas heating reforming device, the device comprising: one or more tubes and a shell surrounding the tubes and defining a shell side with the tubes, wherein the shell includes an inlet and an outlet for a heat exchange medium; The method comprises the step of providing the shell side with a water gas shift catalyst located at one or more regions of the shell side where a heat exchange medium in contact with the shell side during use has a temperature of 500°C to 750°C.

17. The method of claim 16, wherein the step of applying a water-gas shift catalyst to the shell side of the reformer involves applying a coating of water-gas shift catalyst to one or more existing tubes.

18. The method of claim 17, wherein the tube is at least partially made of steel.

19. The method of claim 16, wherein the step of applying a water-gas shift catalyst to the shell side of the reformer involves replacing one or more of the tubes with a tube having a water-gas shift catalyst applied to an outer surface thereof.

20. Use of a water-gas shift catalyst on the shell side of a gas heated reformer according to any one of claims 1 to 7 for preventing metal dusting.

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