Method for preventing metal dusting in gas-heated reformers

Abstract

This specification describes a gas-fired reformer apparatus comprising one or more tubes containing a steam reforming catalyst and a shell surrounding the tubes and defining a shell side together with the tubes, the shell comprising an inlet and an outlet for a heat exchange medium, the shell side comprising a water-gas shift catalyst disposed in 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 500-750°C. Also described is a plant for producing hydrogen, ammonia, or methanol comprising a gas-fired reformer. The water-gas shift catalyst can be retrofitted to an existing gas-fired 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 technology]

[0002] In steam reforming, a process gas containing a mixture of hydrocarbon feedstock and steam, and optionally carbon dioxide, is passed at high pressure through catalyst-filled heat exchange tubes that are externally heated by a suitable heat exchange medium (typically a hot gas mixture). The heat exchange medium can be a combusted hydrocarbon fuel, flue gas, or the process gas passed through the tubes and then subjected to further processing before being used as a heat exchange medium. For example, British Patent No. 1,578,270 describes a process in which primary reformed gas is subjected to partial oxidation, where it is partially combusted with oxygen or air, and then optionally passed through a secondary reforming catalyst bed (a process known as secondary reforming). The resulting partially combusted gas (this term includes secondary reformed gas) is then used as a heat exchange medium and passed through the shell side of the primary reformer to heat the tubes. When secondary reformed gas is used as a heat exchange medium, it typically contains methane, hydrogen, carbon oxides, steam, and any gases, such as nitrogen, that are present in the feedstock and are inert under the conditions used. When flue gas is used as the heat exchange medium, the flue gas typically contains large amounts of carbon oxides, water vapor, and inert gases.

[0003] Heat exchange reformers are typically fabricated from materials containing iron and nickel. Undesirable side reactions can occur under certain conditions on the shell side of a heat exchange reformer apparatus. 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 result either directly or indirectly from catalytic interactions between metals present in the material forming the shell side and carbon monoxide (CO) and / or methane present in the heat exchange medium. In steam reforming, where the heat exchange medium in the primary reformer is primary reformed gas that has undergone further processing, this problem is further exacerbated by the desire to operate at lower steam-to-hydrocarbon ratios for economic reasons, which results in increased reduction potential of the gas, as evidenced by increased CO concentrations.

[0004] Methanation is the conversion of carbon oxides to methane and water, i.e., in the case of CO methanation, it is the reverse of steam reforming and is promoted by, for example, nickel. The CO reaction is shown below: CO + 3H2 → CH4 + H2O (Reaction 1)

[0005] The water-gas shift (WGS) reaction is the reaction of carbon monoxide with water vapor to produce carbon dioxide and hydrogen, and is promoted by, for example, iron. This reaction is shown below: CO + H2O → CO2 + H2 (Reaction 2)

[0006] Carburization is believed to result from the interaction of carbon deposits with the metal in the reactor tube. The deposited carbon can result from CO reduction, CO disproportionation, and hydrocarbon decomposition reactions. These reactions occur on the metal surface and can be catalyzed by Fe, Ni, or Cr. The carbon formation reactions are shown below: Reduction: CO + H2 → C + H2O (Reaction 3) Disproportionation: 2CO→C+CO2 (reaction 4) Decomposition: CH4 → C + 2H2 (reaction 5).

[0007] Carburization of materials, also known as "metal dusting," leads to corrosion of metal surfaces, which can result in, for example, failure of reformer tubes. Increased methane concentrations in process gases can also result from hydrogenation of deposited carbon.

[0008] Because process efficiency and corrosion are driven by carbon monoxide reactions, it is desirable to reduce the interaction between carbon monoxide (CO) present in the heat exchange medium and the metals on the shell side of the reformer unit.

[0009] One approach to preventing shell-side corrosion is to include additives in the inlet gas, such as sulfur-containing compounds (WO 00 / 09441 (ICI)), mixtures of sulfur-containing and phosphorus-containing compounds (WO 01 / 66806 (Kalina)), or compounds containing at least one atom selected from phosphorus, tin, antimony, arsenic, lead, bismuth, copper, germanium, silver, or gold (WO 03 / 051771 (Johnson Matthey)).

[0010] 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.

[0011] Another approach to passivating metal surfaces is by applying a coating. For example, U.S. Patent Application Publication No. 2011 / 305605 (BASF) describes a process for protecting metal surfaces from chemical attack at high temperatures by applying a layer-forming composition containing a nanoscale powder, a porous ceramic powder, and a solvent to the metal surface to be protected and solidifying the layer-forming composition. The resulting layer is porous with a very large internal surface and can decompose impurities without the need for a catalyst.

[0012] Another approach is to use ceramic tubes in the reformer, as described in WO 2013 / 182425 (Casale).

[0013] There is a need for an alternative method to prevent methanation and metal dusting on the shell side of a gas-fired reformer. Ideally, a solution could be found that could be retrofitted to existing gas-fired reformers without requiring a complete replacement of the tubes within the reformer. Summary of the Invention

[0014] The inventors have discovered that the inclusion of a water-gas shift (WGS) catalyst on the shell side of a gas-heated reformer solves the above problems and also provides many other advantages. As used herein, the term "gas-heated reformer" refers to an apparatus having one or more tubes with a shell surrounding the tubes. The inner surfaces of the tubes define the tube-side. The outer surfaces of the tubes and the inner surface of the shell together define the shell-side. Gas-heated reformers are sometimes referred to in the literature as heat exchange reformers.

[0015] As previously mentioned, 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 between CO and steam on the shell side of the reformer via the WGS reaction (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. An additional advantage is that because the WGS reaction is exothermic, it can be used to promote the endothermic steam reforming reaction that occurs within the tubes of a gas-fired reformer. While it is known to operate a water-gas shift unit downstream of a gas-fired reformer, to the inventors' knowledge, including a WGS catalyst on the shell side of the reformer for the purpose of preventing metal dusting has not previously been considered.

[0016] GB 2179366(A) describes a process for producing synthesis gas using a configuration including a primary reactor and a secondary reformer, where the effluent from the secondary reformer is sent to a primary reforming zone in 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 configuration is that as the gas from the secondary reformer cools, reaction 2 proceeds to the right to maintain chemical equilibrium, thereby providing heat to the cooler end of the exchanger. This reference neither describes nor recognizes the advantage of using a WGS catalyst appropriately positioned to prevent metal dusting.

[0017] In a first aspect, the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis, comprising: one or more tubes containing a steam reforming catalyst; a shell surrounding the tube and defining a shell side together with the tube; A gas-heating reformer apparatus comprising: the shell having an inlet and an outlet for a heat exchange medium; and The apparatus is provided with a water gas shift catalyst disposed on the shell side in 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 500-750°C.

[0018] The gas-heated reformer may be a component of a plant for producing hydrogen, ammonia, or methanol.

[0019] In a second aspect, the present invention relates to a plant for producing hydrogen, ammonia or methanol, comprising a gas-heated reformer according to the first aspect.

[0020] In a third aspect, the present invention provides a process carried out in a gas-heated reformer apparatus according to the first aspect, comprising: providing a heat exchange medium comprising synthesis gas to a shell-side inlet; performing a water gas shift on the shell side; The present invention relates to a process including:

[0021] In a fourth aspect, the present invention provides a method of retrofitting a gas-heated reformer apparatus, the apparatus comprising one or more tubes and a shell surrounding the tubes and defining a shell side together with the tubes, the shell comprising an inlet and an outlet for a heat exchange medium; The method includes providing the shell side with a water gas shift catalyst disposed in 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 between 500 and 750°C.

[0022] The modified gas-heated reformer is a reformer according to the first aspect.

[0023] In a fifth aspect, the present invention relates to the use of a water gas shift catalyst in the shell side of a gas-heated reformer apparatus according to the first aspect to prevent metal dusting. DETAILED DESCRIPTION OF THE INVENTION

[0024] Any subheadings are included for convenience only and are not intended as limiting the disclosure in any way.

[0025] Gas-heated reformer In a conventional gas-fired reformer apparatus, a process fluid (typically a mixture containing hydrocarbons and steam) is passed from a process fluid supply zone through heat exchange tubes containing a steam reforming catalyst. The heat exchange tubes (hereinafter "tubes") are positioned within a heat exchange zone defined by a shell through which the heat exchange medium is passed, and then within 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 GB 1578270 (Pullman Inc) and WO 97 / 05947 (ICI).

[0026] The "tube side" of such a reformer apparatus shall be interpreted as including all surfaces within the tubes of said apparatus. The volume defined by the tube side is referred to herein as the "tube side volume." The tubes of a gas-fired reformer contain a steam reforming catalyst. The steam reforming catalyst may be included as a coating on the inner surface of the tube, although it is preferred that the catalyst be disposed within the tube side volume rather than as a coating on the inner surface of the tube. For example, the tube side volume may contain one or more catalyst beds containing the steam reforming catalyst. Alternatively, the tube side volume may contain one or more structures coated with the steam reforming catalyst. Such structured catalysts are described, for example, in WO 2012 / 103432 and WO 2013 / 151885 (Johnson Matthey) and are commercially available from Johnson Matthey as CATACEL™ technology.

[0027] The "shell side" of such a reformer apparatus shall be interpreted to include all surfaces within the shell of the apparatus 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 surface of the tubes, the outer surface of any fins attached to the tubes to increase heat transfer area, the surface of any sheath tubes that surround the heat exchange tubes, the surface of any tube plate that defines the boundary of the heat exchange zone and is exposed to the heat exchange medium, and the outer surface of any header pipes within the heat exchange zone. The volume defined by the shell side is referred to herein as the "shell-side volume."

[0028] In the present invention, the shell side is provided with a WGS catalyst disposed in one or more regions of the shell side where the heat exchange medium in contact with the shell side has a temperature between 500 and 750°C during use. A wide variety of WGS catalysts can be used in the present invention. The WGS catalyst should be selected so that it can promote the WGS reaction without promoting the methanation reaction. The WGS catalyst must be matched to the temperature of the heat exchange medium in the region of the shell side that is susceptible to metal dusting. Generally, the region susceptible to metal dusting is the region where the heat exchange medium temperature is between 500 and 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 heat exchange medium in contact with the shell side has a temperature between 500 and 750°C can be predetermined through simulation. Suitable WGS catalysts that can operate under these conditions are variously referred to in the art as "high-temperature shift" or "ultra-high-temperature shift" catalysts. A wide variety of WGS catalysts capable of operating at these temperatures are known in the art, and one of skill in the art would be able to select a suitable catalyst taking into account the temperature and pressure of the heat exchange medium. In some embodiments, the WGS catalyst is disposed only in the region of the shell side where the heat exchange medium in contact with the shell side has a temperature of 500-750°C during use. For the avoidance of doubt, the WGS catalyst may be disposed over the entire shell side surface, or only a portion thereof, that has a temperature of 500-750°C during use.

[0029] Examples of "high temperature" WGS catalysts capable of operating at temperatures between 400 and 750° C. are described in EP 1149799 A1 (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, which are capable of forming basic oxides.

[0030] Examples of "ultra-high" temperature shift catalysts capable of operating at temperatures between 450 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.

[0031] A further example of an "ultra-high" temperature shift catalyst capable of operating at temperatures between 450 and 900°C is described in US Patent Application Publication No. 2009 / 0232728 A1 (Sud-Chemie Inc), the contents of which are incorporated herein by reference. This catalyst is suitable for use in catalysts with a temperature of 30 to 200 m 2 rhenium deposited on a support having a surface area of ​​1 / g.

[0032] In a preferred embodiment, the WGS catalyst is provided as a coating on the outer surface of the tubes. One advantage of this configuration is that the WGS catalyst can be retrofitted to existing gas-fired reformer equipment by applying the coating to the existing tubes, which can provide cost savings compared to installing new tubes coated with the WGS catalyst. An additional advantage of this configuration is that the coating provides a physical barrier between the tubes and the heat exchange medium, which also helps prevent metal dusting. The coating may be a continuous coating or a partial coating over a portion of the outer surface of the tubes. To reduce unnecessary costs, the coating is preferably a partial coating located on the portion of the shell side that is most susceptible to dusting, taking into account the temperature and gas composition across the shell side.

[0033] Alternatively, instead of being applied as a coating to the exterior of the tubes, the WGS catalyst may be provided within the shell volume, for example as a bed of formed catalyst particles (e.g., pellets), or as a structured catalyst, which may in each case be in the form of a metal or ceramic monolith or a folded metal or ceramic structure, coated with the water-gas shift catalyst. Such structured catalysts are described, for example, in WO 2012 / 103432 and WO 2013 / 151885 (Johnson Matthey) and are commercially available from Johnson Matthey as CATACEL™ technology.

[0034] In a preferred embodiment, the gas-fired reformer tubes are at least partially made of steel, nickel-containing steel, or a nickel-based alloy. As used herein, the term "steel" refers to an iron-based alloy containing iron as its single largest component and also containing carbon. Steels used to manufacture tubes for gas-fired reformers typically also contain nickel, i.e., nickel-containing steel. Alternative materials for gas-fired reformer tubes include nickel-based alloys containing nickel as its single largest component, such as Inconel®. Preferably, at least a portion of the outer surface of the tubes 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. A further advantage of the present invention is that it expands the number of materials that can be used for gas-fired reformer tubes, allowing for the use of less expensive materials.

[0035] A gas-heated reformer is typically a component of a plant used to produce synthesis gas. The synthesis gas may be used in downstream processes (e.g., hydrogen, methanol, or ammonia production). It will be appreciated that the degree of water-gas shift on the shell side is more targeted when the gas-heated reformer is a component of a plant for producing methanol compared to situations where the gas-heated reformer is a component of a plant for producing hydrogen or ammonia. In the latter case, it is less important to control the degree of WGS on the shell side because the plant typically includes various processes downstream of the gas-heated reformer to maximize hydrogen production.

[0036] The present invention also relates to a plant for producing hydrogen, ammonia or methanol, comprising a gas-heated reformer according to the first aspect.

[0037] In a preferred embodiment, the plant comprises a gas-heated reformer and an autothermal reformer arranged in series, and arranged so that partially reformed gas from the autothermal reformer is fed to the shell side of the gas-heated reformer to provide heating for the reforming reactions taking place in the tube side of the gas-heated reformer.

[0038] process The invention also relates to a steam reforming process carried out using an apparatus according to the first aspect.

[0039] The method of the present invention is particularly useful in catalytic steam reformers used for steam reforming of hydrocarbons. In a typical process, a mixture containing a hydrocarbon feedstock and steam, possibly also carbon dioxide or other components, is passed at high pressure through catalyst-filled heat exchange tubes that are externally heated by a suitable heat exchange medium (typically a hot gas mixture) to a maximum temperature in the range of 700°C to 900°C to form a primary reformed gas. Catalysts for carrying out primary reforming include shaped units, such as cylinders, rings, saddles, and cylinders with multiple perforations, and are typically formed from a refractory support material, such as alumina, calcium aluminate cement, magnesia, or zirconia, impregnated with a suitable catalytically active material, often nickel and / or ruthenium. Examples of commercially available reforming catalysts include the KATALCO™ steam reforming catalyst manufactured by Johnson Matthey. Structured catalysts may also be used in the reformer tubes.

[0040] The hydrocarbon feedstock may comprise any gaseous or low-boiling hydrocarbon feedstock, such as natural gas. The hydrocarbon feedstock is preferably methane or natural gas containing a substantial proportion of methane, for example, greater than 90% v / v methane. The feedstock is preferably compressed to a pressure in the range of 20 to 80 bar (absolute).

[0041] The method and apparatus of the present invention differs from conventional heat exchange reformer apparatus in that the WGS catalyst is present on the shell side. As previously mentioned, the role of the WGS catalyst is to reduce the concentration of CO on the shell side, thereby reducing or preventing metal dusting and methanation.

[0042] The heat exchange medium supplied to the shell side is synthesis gas, which means a gas containing CO and H. Preferably, the heat exchange medium is primary reformed gas (formed in the tubes of the gas-heated reformer) that has undergone further processing; in this case, the heat exchange medium also contains water vapor, CO, and low concentrations of CH. In a preferred embodiment, the heat exchange medium is primary reformed gas exiting the process fluid discharge zone that has been subjected to a further processing step. The further processing step is typically partial combustion with an oxygen-containing gas, such as air, oxygen-enriched air, or oxygen. Preferably, the partially burned primary reformed gas is then passed through a bed of secondary reforming catalyst to effect further reforming (i.e., secondary reforming) before being used as the heat exchange medium.

[0043] Preferably, hydrocarbon conversion is essentially complete 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.

[0044] The reformed synthesis gas (heat exchange medium) is fed into an inlet on the shell side of the gas-fired reformer. Typically, the gas entering the inlet has a temperature of 700°C or higher.

[0045] The pressure of the heat exchange medium supplied to the shell-side inlet is typically 20 to 80 bar (absolute), preferably 20 to 55 bar (absolute), more preferably 20 to 45 bar (absolute).

[0046] The heat exchange medium is contacted with a WGS catalyst on the shell side to convert CO and water vapor present in the heat exchange medium to CO and H. The heat exchange medium at the outlet from the shell side has a reduced CO concentration compared to the heat exchange medium at the input to the shell side.

[0047] The shell-side outlet may require further downstream processing to achieve an acceptable yield of H. Typically, a WGS unit is located downstream of the shell-side outlet. Those skilled in the art will be aware of suitable WGS unit designs.

[0048] The outlet from the shell side, which has optionally undergone further reactions to increase H2 yield, can be treated downstream to remove contaminants (CO2, hydrocarbons, etc.).

[0049] Modification method An advantage of the present invention is that the WGS catalyst can be retrofitted to the shell side of an existing reformer during reactor downtime, the existing apparatus comprising one or more tubes and a shell surrounding the tubes and defining the shell side together with the tubes, the shell comprising an inlet and an outlet for a heat exchange medium.

[0050] The method includes providing a water-gas shift catalyst on the shell side. The resulting reformer may be as described in the first aspect. The configuration and type of water-gas shift catalyst may be as described under the heading "Gas-Heated Reformer." The features described as preferred under the heading "Gas-Heated Reformer" also apply to the modified unit.

[0051] In one embodiment, the method includes applying a coating of water gas shift catalyst onto one or more existing tubes. An advantage of this method is that it does not require replacement of the reformer tubes and is a relatively cost-effective way of upgrading existing reformers.

[0052] In one embodiment, the method includes replacing one or more of the tubes with a tube having a water gas shift catalyst applied to its exterior surface, which may be appropriate when a tube is nearing the end of its useful life and requires replacement. [Brief explanation of the drawings]

[0053] The present invention is further described with reference to FIG. 1, which shows a process flowsheet incorporating one embodiment of the present invention.

[0054] [Figure 1]Referring to FIG. 1, high-pressure natural gas, typically in the range of 15 to 50 bar (absolute), is supplied via line 10 and mixed with a small amount of hydrogen-containing gas supplied via line 12. The mixture is then heated in heat exchanger 14 and supplied to desulfurization stage 16, where the gas mixture is contacted with a bed of a hydrodesulfurization catalyst, such as nickel molybdate or cobalt molybdate, and an absorbent for the hydrogen sulfide formed by hydrodesulfurization, such as zinc oxide. The desulfurized gas mixture is then supplied via line 18 to saturator 20, where it is contacted with a heated water stream supplied via line 22. The saturated gas exits the saturator via line 24 and may be subjected to a low-temperature adiabatic reforming step, if desired. The saturated gas may be mixed with recycled carbon dioxide, supplied via line 26, if desired, and then heated to the desired heat exchange reformer inlet temperature in heat exchanger 28. The heated process gas is then supplied via line 30 to the catalyst-containing tubes of the heat exchange reformer 32. The heat exchange reformer has a process fluid supply zone 34, a heat exchange zone 36, a process fluid discharge zone 38, and first and second boundary means 40 and 42 separating the zones from one another. The process fluid undergoes steam reforming in a plurality of heat exchange tubes 44 containing steam reforming catalyst to produce a primary reformed gas stream. While only four tubes are shown, those skilled in the art will appreciate that in practice there may be tens or hundreds of such tubes. The primary reformed gas stream is then sent from the heat exchange tubes 44 to the process fluid discharge zone 38, from which it is sent via line 46 for further processing. Further processing involves partial combustion with an oxygen-containing gas supplied via line 48 in a vessel containing a bed of secondary reforming catalyst 50, such as calcium aluminate or nickel supported on alumina. The resulting secondary reformed gas is sent via line 52 to the heat exchange zone 36 as a heat exchange medium. A heat exchange medium is passed through the gaps between the heat exchange tubes, thereby providing 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 exits the reactor via line 56. [Figure 2]1 shows the outlet concentrations of CO, CO2, and CH4 produced in Comparative Example 1. [Figure 3] 1 shows the outlet concentrations of CO, CO2, and CH4 produced in Example 2. [Example]

[0055] Example 1 (Comparative Example) A 3 mm diameter rod of Incoloy® 800 HT®, a Ni-Fe-Cr alloy containing C, Al, and Ti additives, was cut into semicircular pieces and placed in the reactor. A total of 73 pellets were loaded into the reactor, with a total mass of 10.9 g and a surface area of ​​approximately 2400 mm². 2 Prior to introducing the process gas, a 24-hour pretreatment in H2 at 615 °C was performed to remove any protective oxide layer from the material surface, thus reducing the time it took for metal dusting to begin. Process gas with 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 steadily increased over the course of the experiment.

[0056] [Table 1]

[0057] Example 2 The procedure of Example 1 was followed, except that the Incoloy® 800 HT® rod was replaced with a rod of Incoloy® 800 HT® that had been cut into semicircular pieces and then coated with CATACEL™ material (a water-gas shift catalyst) from Johnson Matthey. The outlet concentrations of CO, CO, and CH were measured and are shown in Figure 3. The outlet concentration of methane remained low over the course of the experiment.

Claims

1. One or more tubes containing a steam reforming catalyst, A shell that surrounds the tube and defines the shell side together with the tube. A gas-heated reformer apparatus comprising, The shell is provided with an inlet and an outlet for a heat exchange medium, The shell side is provided with a water-gas shift catalyst arranged in one or more regions of the shell side. The tube is made at least partially of steel, nickel-containing steel, or a nickel-based alloy. The aqueous gas shift catalyst is provided as a coating on the outer surface of the tube, The gas heating reformer apparatus is configured to operate with the heat exchange medium in contact with the shell side at a temperature of 500 to 750°C. Device.

2. The apparatus according to claim 1, wherein the aqueous gas shift catalyst is positioned only in a region of the shell side in which the heat exchange medium that comes into contact with the shell side during use has a temperature of 500 to 750°C.

3. The apparatus according to claim 1 or 2, wherein the steam reforming catalyst is disposed within the tube-side volume section.

4. The apparatus according to claim 3, wherein the tube-side volume section includes one or more catalyst beds containing a steam reforming catalyst.

5. The apparatus according to claim 3, wherein the tube-side volume portion includes one or more structures coated with a steam reforming catalyst.

6. A plant for producing hydrogen, ammonia, or methanol, comprising the gas-heated reformer apparatus described in claim 1.

7. The plant according to claim 6, comprising a gas-heated reformer and a self-heating reformer arranged in succession, wherein a partially reformed gas from the self-heating reformer is supplied to the shell side of the gas-heated reformer to provide heating for a reforming reaction carried out on the tube side of the gas-heated reformer.

8. A steam reforming process carried out in a heat exchange reformer apparatus according to claim 1, A step of providing a heat exchange medium containing synthesis gas to the inlet on the shell side, The process of performing a water-gas shift on the shell side A process that includes this.

9. The process according to claim 8, wherein the synthesis gas supplied to the inlet on the shell side has a methane content of less than 10% by volume.

10. The process according to claim 8, wherein the synthesis gas supplied to the inlet on the shell side has a methane content of less than 5% by volume.

11. The process according to claim 8, wherein the temperature of the heat exchange medium supplied to the inlet on the shell side is 700°C or higher.

12. The process according to claim 8, wherein the pressure of the heat exchange medium supplied to the inlet is 20 to 80 bar (absolute pressure).

13. The process according to claim 8, wherein the pressure of the heat exchange medium supplied to the inlet is 20 to 55 bar (absolute pressure).

14. A method for modifying a gas heating reformer apparatus, wherein the apparatus is It comprises one or more tubes and a shell surrounding the tubes and defining the shell side together with the tubes, the shell having an inlet and an outlet for a heat exchange medium, The heat exchange medium that comes into contact with the shell during use has a temperature of 500 to 750°C. The tube is made of steel, at least partially. The method includes the step of providing a water-gas shift catalyst, which is arranged in one or more regions on the shell side, to the shell side. The step of applying the water-gas shift catalyst to the shell side of the reformer includes applying a coating of the water-gas shift catalyst to one or more existing tubes. method.

15. Use of a water-gas shift catalyst on the shell side of the gas-heated reformer apparatus according to claim 1 to prevent metal dusting.

Images