ENDOTHERMIC REACTIONS HEATED BY RESISTANCE HEATING

Abstract

A reactor system for carrying out an endothermic reaction of a feed gas, including: a structured catalyst arranged for catalyzing the endothermic reaction of a feed gas, the structured catalyst including a macroscopic structure of electrically conductive material, the macroscopic structure supporting a ceramic coating, wherein the ceramic coating supports a catalytically active material; a pressure shell housing the structured catalyst; heat insulation layer between the structured catalyst and the pressure shell; at least two conductors electrically connected to the electrically conductive material and to an electrical power supply placed outside the pressure shell, wherein the electrical power supply is dimensioned to heat at least part of said structured catalyst to a temperature of at least 200° C. by passing an electrical current through the electrically conductive material. Also, a process for performing an endothermic reaction of a feed gas.

Claims

1. A reactor system for carrying out an endothermic reaction of a feed gas, said reactor system comprising: a structured catalyst arranged for catalyzing said endothermic reaction of said feed gas, said structured catalyst comprising a macroscopic structure of electrically conductive material, said macroscopic structure supporting a ceramic coating, wherein said ceramic coating supports a catalytically active material; a pressure shell housing said structured catalyst; a heat insulation layer between said structured catalyst and said pressure shell; and at least two conductors electrically connected to said structured catalyst and to an electrical power supply placed outside said pressure shell, wherein said electrical power supply is dimensioned to heat at least part of said structured catalyst to a temperature of at least 200° C. by passing an electrical current through said electrically conductive material.

2. The reactor system according to claim 1, wherein the pressure shell has a design pressure of between 2 and 30 bar.

3. The reactor system according to claim 1, wherein the pressure shell has a design pressure of between 30 and 200 bar.

4. The reactor system according to claim 1, wherein the resistivity of the electrically conductive material is between 10.sup.−5 Ω.Math.m and 10.sup.−7 Ω.Math.m.

5. The reactor system according to claim 1, where said at least two conductors are led through the pressure shell in a fitting so that the at least two conductors are electrically insulated from the pressure shell.

6. The reactor system according to claim 5, wherein said pressure shell further comprises one or more inlets close to or in combination with at least one fitting in order to allow a cooling gas to flow over, around, close to, or inside at least one conductor within said pressure shell.

7. The reactor system according to claim 1, wherein the reactor system further comprises an inner tube in heat exchange relationship with but electrically insulated from the structured catalyst, said inner tube being adapted to withdraw a product gas from the structured catalyst so that the product gas flowing through the inner tube is in heat exchange relationship with gas flowing over the structured catalyst.

8. The reactor system according to claim 1, wherein the connection between the structured catalyst and said at least two conductors is a mechanical connection, a welded connection, a brazed connection or a combination thereof.

9. The reactor system according to claim 1, wherein the electrically conductive material comprises an 3D printed or extruded and sintered macroscopic structure, said macroscopic structure is supporting a ceramic coating, wherein said ceramic coating supports a catalytically active material

10. The reactor system according to claim 1, wherein the structured catalyst comprises an array of macroscopic structures electrically connected to each other.

11. The reactor system according to claim 9, wherein said macroscopic structure has a plurality of parallel channels, a plurality of non-parallel channels and/or a plurality of labyrinthic channels.

12. The reactor system according to claim 1, wherein the reactor system further comprises a bed of a second catalyst material upstream said structured catalyst within said pressure shell.

13. The reactor system according to claim 11, wherein said reactor system further comprises a third catalyst material in the form of catalyst pellets, extrudates or granulates loaded into the channels of said macroscopic structure.

14. The reactor system according to claim 1, wherein said reactor system further comprises a control system arranged to control the electrical power supply to ensure that the temperature of the gas exiting the pressure shell lies in a predetermined range and/or to ensure that the conversion of the feed gas lies in a predetermined range.

15. The reactor system according to claim 1, wherein the structured catalyst within said reactor system has a ratio between the area equivalent diameter of a horizontal cross section through the structured catalyst and the height of the structured catalyst in the range from 0.1 to 2.0.

16. The reactor system according to claim 1, wherein the height of the reactor system is between 0.5 and 7 m, more preferably between 0.5 and 3 m.

17. A process for carrying out an endothermic reaction of a feed gas in a reactor system comprising a pressure shell housing a structured catalyst arranged for catalyzing said endothermic reaction of a feed gas, said structured catalyst comprising a macroscopic structure of electrically conductive material, said macroscopic structure supporting a ceramic coating, wherein said ceramic coating supports a catalytically active material; wherein said reactor system is provided with heat insulation between said structured catalyst and said pressure shell; said process comprising the following steps: pressurizing said feed gas to a pressure of at least 2 bar, supplying said pressurized feed gas to the reactor system, allowing the feed gas to undergo the endothermic reaction over the structured catalyst and outletting a product gas from the reactor system, and supplying electrical power via electrical conductors connecting an electrical power supply placed outside said pressure shell to said structured catalyst, allowing an electrical current to run through said electrically conductive, thereby heating at least part of the structured catalyst to a temperature of at least 200° C.

18. The process according to claim 17, further comprising the step of pressurizing the feed gas upstream the pressure shell to a pressure of between 2 and 30 bar.

19. The process according to claim 17, further comprising the step of pressurizing the feed gas upstream the pressure shell to a pressure of between 30 and 200 bar, preferably between 80 and 180 bar.

20. The process according to claim 17, wherein the temperature of the feed gas let into the reactor system is between 100° C. and 700° C.

21. The process according to claim 17, wherein the structured catalyst is heated so that the maximum temperature of the structured catalyst lies between 200° C. and 1300° C.

22. The process according to claim 17, further comprising the step of inletting a cooling gas through an inlet through the pressure shell in order to allow said cooling gas to flow over at least one conductor.

23. The process according to claim 17, where the endothermic reaction is dehydrogenation of hydrocarbons.

24. The process according to claim 17, where the endothermic reaction is cracking of methanol.

25. The process according to claim 17, where the endothermic reaction is steam reforming of hydrocarbons.

26. The process according to claim 17, where the endothermic reaction is ammonia cracking.

27. The process according to claim 17, where the endothermic reaction is hydrogen cyanide synthesis or a synthesis process for organic nitriles.

28. The process according to claim 17, where the endothermic reaction is aromatization of hydrocarbons.

Description

SHORT DESCRIPTION OF THE FIGURES

[0106] FIG. 1a shows a cross section through an embodiment of the inventive reactor system with a structured catalyst comprising an array of macroscopic structures, in a cross section;

[0107] FIG. 1b shows the reactor system of FIG. 1a with a part of the pressure shell and heat insulation layer removed;

[0108] FIG. 2 is an enlarged view of a part of the reactor system;

[0109] FIGS. 3a and 3b show schematic cross sections through an embodiment of the inventive reactor system comprising a structured catalyst;

[0110] FIGS. 4 and 5 show an embodiment of a structured catalyst with an array of macroscopic structures as seen from above and from the side, respectively;

[0111] FIG. 6 shows an embodiment of the structured catalyst of the invention;

[0112] FIGS. 7, 8 and 9 shows embodiments of a structured catalyst with connectors;

[0113] FIG. 10 shows the required maximum temperature within the reactor system of the invention as a function of the pressure; and

[0114] FIG. 11 is a graph of the approach to equilibrium (ΔT.sub.app,SMR) of the steam methane reforming reaction for different gas flow rates over a structured catalyst.

DETAILED DESCRIPTION OF THE FIGURES

[0115] Throughout the Figures, like reference numbers denote like elements.

[0116] FIG. 1a shows a cross section through an embodiment of a reactor system 100 according to the invention. The reactor system 100 comprises a structured catalyst 10, arranged as an array of macroscopic structures 5. Each macroscopic structure 5 in the array is coated with a ceramic coating impregnated with catalytically active material. The reactor system 100 moreover comprises conductors 40, 40′ connected to a power supply (not shown in the Figures) and to the structured catalyst 10, viz. the array of macroscopic structures. The conductors 40, 40′ are led through the wall of a pressure shell 20 housing the structured catalyst and through insulating material 30 on the inner side of the pressure shell, via fittings 50. The conductors 40′ are connected to the array of macroscopic structures 5 by conductor contact rails 41.

[0117] In an embodiment, the electrical power supply supplies a voltage of 26V and a current of 1200 A. In another embodiment, the electrical power supply supplies a voltage of 5V and a current of 240 A. The current is led through electrical conductors 40, 40′ to conductor contact rails 41, and the current runs through the structured catalyst 10 from one conductor contact rail 41, e.g. from the conductor contact rail seen to the left in FIG. 1a, to the other conductor contact rail 41, e.g. the conductor contact rail seen to the right in FIG. 1a. The current can be both alternating current, and e.g. run alternating in both directions, or direct current and run in any of the two directions.

[0118] The macroscopic structures 5 are made of electrically conductive material. Especially preferred is the alloy kanthal consisting of aluminum, iron and chrome. The ceramic coating, e.g. an oxide, coated onto the structure catalysts 5 is impregnated with catalytically active material. The conductors 40, 40′ are made in materials like iron, aluminum, nickel, copper or alloys thereof.

[0119] During operating, a feed gas enters the reactor system 100 from above as indicated by the arrow 11 and exits the reactor system from the bottom thereof as indicated by the arrow 12.

[0120] FIG. 1b shows the reactor system 100 of FIG. 1a with a part of the pressure shell 20 and heat insulation 30 layer removed and FIG. 2 is an enlarged view of a part of the reactor system 100. In FIGS. 1b and 2 the connections between conductors 40′ and conductor contact rails 41 are shown more clearly than in FIG. 1a. Moreover, it is seen that the conductors 40 are led through the walls of the pressure shell in a fitting 50, and that the one conductor 40 is split up into three conductors 40′ within the pressure shell. It should be noted, that the number of conductors 40′ may be any appropriate number, such as smaller than three or even larger than three.

[0121] In the reactor system shown in FIGS. 1a, 1b and 2, the conductors 40, 40′ are led through the wall of a pressure shell 20 housing the structured catalyst and through insulating material 30 on the inner side of the pressure shell, via fittings 50. Feed gas for steam reforming is inlet into the reactor system 100 via an inlet in the upper side of the reactor system 100 as shown by the arrow 11, and reformed gas exists the reactor system 100 via an outlet in the bottom of the reactor system 100 as shown by the arrow 12. Moreover, one or more additional inlets (not shown in FIGS. 1a to 2) advantageously exist close to or in combination with the fittings 50. Such additional inlets allow a cooling gas to flow over, around, close to, or inside at least one conductor within the pressure shell to reduce the heating of the fitting. The cooling gas could e.g. be hydrogen, nitrogen, steam, carbon dioxide or mixtures thereof. The temperature of the cooling gas at entry into the pressure shell may be e.g. about 100° C.

[0122] In the reactor system 100 shown in FIGS. 1a to 2, inert material (not shown in FIGS. 1a-2) is advantageously present between the lower side of the structured catalyst 10 and the bottom of the pressure shell. Moreover, inert material is advantageously present between the outer sides of the structured catalyst 10 of macroscopic structures 5 and the insulating material 30. Thus, one side of the insulating material 30 faces the inner side of the pressure shell 20 and the other side of the insulating material 30 faces the inert material. The inert materiel is e.g. ceramic material and may be in the form of pellets. The inert material assists in controlling the pressure drop across the reactor system 100 and in controlling the flow of the gas through the reactor system 100, so that the gas flows over the surfaces of the structured catalyst 10.

[0123] FIGS. 3a and 3b show schematic cross sections through an embodiment of the inventive reactor system 100′, 100″ comprising a structured catalyst 10′. The structured catalyst 10′ may consist of a single macroscopic structure with ceramic coating supporting catalytically active material or it may contain two or more macroscopic structures. Each of the reactor systems 100′, 100″ comprises a pressure shell 20 and a heat insulation layer 80 between the structured catalyst 10′ and the pressure shell 20. Inert material 90 can be used to fill the gap between the structured catalyst 10′ and the heat insulation layer or the pressure shell 20. In FIGS. 3a and 3b, the inert material 90 is indicated by dotted area; the inert material 90 may be in any appropriate form, e.g. in the form of inert pellets, and it is e.g. of ceramic material. The inert material 90 assists in controlling the pressure drop through the reactor system and in controlling the flow of the gas through the reactor system. Moreover, the inert material typically has a heat insulating effect.

[0124] From FIGS. 3a and 3b it is seen that the reactor systems 100′, 100″ further comprise an inner tube 15 in heat exchange relationship with the structured catalyst 10′. The inner tube 15 is adapted to withdraw a product gas from the structured catalyst 10′ so that the product gas flowing through the inner tube or tubes is in heat exchange relationship with the gas flowing over the structured catalyst; however, the inner tube 15 is electrically insulated from the structured catalyst 10′ by either a heat insulation layer 80, inert material 90, a gap, or a combination. This is a layout which is denoted a bayonet reactor system. In this layout, the product gas within the inner tube assists in heating the process gas flowing over the macroscopic structure. In the layouts shown in FIGS. 3a and 3b, the feed gas enters the reactor system 100′, 100″ as indicated by the arrow 11, and continues into the structured catalyst 10′ as indicated by the arrows 13. During the passage of the feed gas over the structured catalyst 10′, it undergoes the steam reforming reaction. The gas exiting the structured catalyst 10′ is at least partly reformed. The at least partly reformed gas flows from the structured catalyst 10′ into the inner tube 15 as indicated by the arrows 14, and exits the inner tube as indicated by the arrows 12. Even though the heat insulation layer 80 is present between the inner tube 15 and the structured catalyst 10′, some heat transfer will take place from the gas within the inner tube 15 and the gas within the structured catalyst 10′ or upstream the structured catalyst 10′. In the embodiments shown in FIGS. 3a and 3b, the feed gas flow downwards through the structured catalyst 10′ and upwards through the inner tube 15; however, it is conceivable that the configuration was turned upside-down so that the feed gas would flow upwards through the structured catalyst 10′ and downwards through the inner tube 15.

[0125] FIGS. 4 and 5 show an embodiment of a structured catalyst comprising an array of macroscopic structures as seen from above and from the side, respectively. FIG. 4 shows a structured catalyst 10 comprising an array of macroscopic structure 5 seen from above, viz. as seen from the arrow 11 in FIGS. 1a and 1b. The array has 6 rows, viz. 1a, 1b, 1c, 1d, 1e and 1f, of five macroscopic structures 5. The macroscopic structures 5 in each row are connected to its neighboring macroscopic structure (s) in the same row and the two outermost macroscopic structures in each row are connected to a conductor contact rail 41. The neighboring macroscopic structure 5 in a row of macroscopic structures are connected to each other by means of a connection piece 3.

[0126] FIG. 5 shows the structured catalyst 10 having an array of macroscopic structures 5 of FIG. 4 seen from the side. From FIG. 5, it can be seen that each macroscopic structure 5 extends longitudinally perpendicular to the cross section seen in FIG. 4. Each macroscopic structure 5 has a slit 60 cut into it along its longitudinal direction (see FIG. 5). Therefore, when energized by the power source, the current enters the array of macroscopic structures 5 via a conductor contact rail 41, is led through the first macroscopic structure 5 downwards until the lower limit of the slit 60 and is subsequently led upwards towards a connection piece 3. The current is led via a corresponding zigzag path, downwards and upwards, through each macroscopic structure 5 in each row 1a-1f of macroscopic structures 5 in the array 10. This configuration advantageously increases the resistance over the structured catalyst 10.

[0127] FIG. 6 shows a structured catalyst 10 according to the invention in a perspective view. The structured catalyst 10 comprises a macroscopic structure that is coated with a ceramic coating impregnated with catalytically active material. Within the structured catalyst are channels 70 extending along the longitudinal direction (shown by the arrow indicate ‘h’ in FIG. 6) of the macroscopic structure 5; the channels are defined by walls 75. In the embodiment shown in FIG. 6, the walls 75 define a number of parallel, square channels 70 when seen from the direction of flow as indicated by the arrow 12. The structured catalyst 10 has a substantially square perimeter when seen from above, defined by the edge lengths e1 and e2. However, the perimeter could also be circular or another shape.

[0128] The walls 75 of the structured catalyst 10 are of extruded or 3D printed material coated with a ceramic coating, e.g. an oxide, which has been coated onto the macroscopic structure. In the Figures, the ceramic coating is not shown. The ceramic coating is impregnated with catalytically active material. The ceramic coating and thus the catalytically active material are present on every walls within the structured catalyst 10 over which the gas flow flows during operation and interacts with the heated surface of the structured catalyst and the catalytically active material.

[0129] Thus, during use in a reactor system for steam reforming, a hydrocarbon feed gas flows through the channels 70 and interacts with the heated surface of the structured catalyst and with the catalytically active material supported by the ceramic coating.

[0130] In the structured catalyst 10 shown in FIG. 6 a slit 60 has been cut into the structured catalyst 10. This slit 60 forces a current to take a zigzag route, in this instance downwards and subsequently upwards, within the macroscopic structure thereby increasing the current path and thus the resistance and consequently the heat dissipated within the macroscopic structure. The slit 60 within the macroscopic structure may be provided with embedded insulating material in order to ensure that no current flows in the transverse direction of the slit 60.

[0131] The channels 70 in the structured catalyst 10 are open in both ends. In use of the structured catalyst in a reactor system, a hydrocarbon feed gas flows through the unit, in the direction shown by arrows 11 and 12 in FIGS. 1a and 1b, and gets heated via contact with the walls 75 of the channels 70 and by heat radiation. The heat initiates the desired steam reforming process. The walls 75 of the channels 70 may e.g. have a thickness of 0.5 mm, and the ceramic coating coated onto the walls 75 may e.g. have a thickness of 0.1 mm. Even though the arrows 11 and 12 (see FIGS. 1a and 1b) indicate that the flow of the hydrocarbon feed gas is down-flow, the opposite flow direction, viz. an up-flow, is also conceivable.

[0132] FIG. 7 shows the structured catalyst 10 of FIGS. 1a and 1b in a perspective view and with connectors 7 attached. The connectors 7 each connects a part of the structured catalyst 10 to a conductor 40. The conductors 40 are both connected to a power supply (not shown). Each of the connectors 7 are connected to an upper part of the structured catalyst. When the conductors 40 are connected to a power supply, an electrical current is led to the corresponding connector 7 via the conductor and runs through the structured catalyst 10. The slit 60 hinders the current flow in a transverse direction (horizontal direction of FIG. 7) throughout its lengths along the height h of the structured catalyst 10. Therefore, the current runs in a direction downwards as seen in FIG. 7 in the part of the structured catalyst along the slit 60, subsequently it runs transversely to the longitudinal direction below the slit 60 as seen in FIG. 7 and finally the current runs upwards in the longitudinal direction of the structured catalyst to the other connector 7. The connectors 7 in FIG. 7 are mechanically fastened to the structured catalyst by means of i.a. mechanical fastening means such as screws and bolts. However, additional or alternative fastening means are conceivable. In an embodiment, the electrical power supply generates a voltage of 3V and a current of 400 A. The connectors 7 are e.g. made in materials like iron, aluminum, nickel, copper or alloys thereof.

[0133] As mentioned, the structured catalyst 10 is coated with a ceramic coating, such as an oxide, supporting the catalytically active material. However, the parts of the structured catalyst 10, which are connected to the connectors 7, should not be coated with an oxide. Instead, the macroscopic structure of the structured catalyst should be exposed or connected directly to the connectors 7 in order to obtain a good electrical connection between the macroscopic structure and the connector.

[0134] When the connectors 7 and thus the conductors 40 are connected to the same end of the structured catalyst 10, viz. the upper end as seen in FIG. 7, the gas entering into a reactor system housing the structured catalyst 10 would be able to cool the connectors 7 and the conductors 40. For instance, the hydrocarbon gas entering into such a reactor system would have a temperature of 400° C. or 500° C. and would thus keep the connectors 7 and conductors 40 from reaching temperatures much higher than this temperature.

[0135] FIG. 8 shows an alternative embodiment of the structured catalyst 10′ with connectors 7′ attached. The structured catalyst 10′ shown in FIG. 8 has a square cross section, like the structured catalyst 10 shown in FIGS. 6 and 7; however, the structured catalyst 10′ of FIG. 8 does not have any slit cut through it. In the upper and lower end of the macroscopic structure 10′ a conductor 40. The material of the conductor 40 is e.g. nickel. Alternatively, other appropriate metals could be used as electrical current distributors, or alloys such as FeCrAlloy. Connectors 7′, 7″ in the form of electrical conducting bars are used for guiding the current across the structured catalyst 10′, i.e. the macroscopic structure. The connectors 7′, 7″ are fastened to the conductors 40 and to the structured catalyst 10′ by use of mechanical fastening means; however, alternative or additional fastening means are also conceivable.

[0136] Connectors 7″ at the lower end of the structured catalyst 10′ may be made of a different material compared to the connectors 7′ at the upper end of the structured catalyst 10′ as seen in FIG. 2. For example, the connectors 7′ may be of cupper, whilst the connectors 7″ may be of nickel. Since nickel has a lower conductivity than cupper, the connectors 7″ are larger than the connectors 7′.

[0137] The embodiment shown in FIG. 8 is suitable for temperatures below 800° C., such as 600-700° C.

[0138] FIG. 9 shows another embodiment of a structured catalyst 10′″ with connectors 7′″. The structured catalyst 10′″ is e.g. the structured catalyst as shown in FIG. 6. Each of the connectors T″ has three holes at an upper side thereof for connection to conductors (not shown). A piece of electrically insulating material 61 is inside the slit 60 (see FIG. 6) of the structured catalyst 10″.

[0139] FIG. 10 shows the required maximum temperature within the reactor system of the invention as a function of the pressure for pressures of about 30 bar to about 170 bar during steam reforming of a feed gas consisting of 30.08% CH.sub.4, 69.18% H.sub.2O, 0.09% Hz, 0.45% CO.sub.2, 0.03% Ar, 0.02% CO, 0.15% N.sub.2 to a methane conversion of 88% at a 10° C. approach to the steam methane reforming equilibrium. The required maximum temperature increases with pressure due to Le Chatelier's principle. This shows that the high temperatures which can be used in the current invention allows for using pressures which are significantly higher than the pressures used in a traditional SMR, where the external heating of the tubes prohibit the temperature exceeding ca. 950° C. A temperature of 950° C. corresponds to 27 barg in FIG. 10. In a reactor system of the invention, a maximum temperature of e.g. 1150° C. can be used which allows for a pressure of up to 146 barg with the same conversion of methane as indicated above.

[0140] A general trend in all the curves in the FIG. 11 is that the approach to equilibrium is continuously decreasing from the entry into the structured catalyst until a pseudo equilibrium is reached, where the heat added and the heat consumed roughly equal each other. The approach to equilibrium from this stage is substantially constant or has a slightly increasing development due to the overall increasing temperature of the reactor system. For e.g. the flow rate 150 000 Nm.sup.3/h, the approach to equilibrium goes below 60° C. at about 80% of the reactor system length, but subsequently increases to about 60° C.

Examples

[0141] While the invention has been illustrated by a description of various embodiments and examples while these embodiments and examples have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.

[0142] All the examples described below relate to compact reactor systems. This is possible due to the reactor systems comprise compact structured catalysts having a high thermal flux when powered by a power source. It is moreover to be noted, that the dimensions of the structured catalysts may be chosen relatively freely, so that the structured catalyst may be almost cubic in outer shape or it may be wider than its height.

[0143] The examples all describe operation conditions with high pressure, ranging from 28 bar to 182 bar. Such high pressures are made possible by the configuration of the reactor system since the structured catalyst within the reactor system has high thermal flux upon powering by a power source, is to some extent thermally insulated from the pressure shell, and the pressure drop through the structured catalyst is very low or even non-existing. The structured catalyst will obtain the highest temperature within the reactor system, while the pressure shell will have a significantly lower temperature due to the thermal insulation between the macroscopic structure and the pressure shell. Ideally, the temperature of the pressure shell will not exceed 500° C. When product gas with a high pressure is needed, such as 30 bar or above, the product gas exiting the reactor system can in many cases be used directly, without the use of compressors. This is due to the possibility of pressurizing the feed gas upstream the reactor system of the invention.

[0144] In all the examples described below, steam reforming is used as example where the feed gas enters the reactor system and flows over the structured catalyst housed therein. When the heat insulation layer of the reactor system is a heat insulating material, the heat insulating material typically makes up most of the space between the structured catalyst and the pressure shell along the walls of the pressure shell so that the feed gas is forced to flow along walls of the macroscopic structure on its way through the pressure shell.

[0145] The examples below (except for the comparative example) all relate to a reactor system with a structured catalyst for steam reforming. The structured catalysts described in these examples comprise one or more macroscopic structures. The one or more macroscopic structures of the examples below all support a ceramic coating supporting catalytically active material. Advantageously, substantially all the surface of the macroscopic structure supports the ceramic coating supporting the catalytically active material; however, at connections points, e.g. between two adjacent macroscopic structures or between a macroscopic structure and a conductor, the macroscopic structure may be free from ceramic coating in order to facilitate connection between a conductor and the macroscopic structure.

Example 1

[0146] An example calculation of the process of the invention is given in Table 1 below. A hydrocarbon feed stream comprising i.a. a hydrocarbon gas, hydrogen and steam is fed to the reactor system of the invention. The feed stream entering the reactor system is pressurized to a pressure of 28 kg/cm.sup.2.Math.g and has a temperature of 500° C. Inside the reactor system, a structured catalyst in the form of nine macroscopic structures having a square cross section are placed in an array and each macroscopic structure has a size of 0.53 times 0.53 times 2.3 meter. Each macroscopic structure additionally has 17778 channels with a square cross section having a side or edge length of 0.32 cm. Each macroscopic structure has slits parallel to the longitudinal direction thereof, so that clusters of 5 times 5 channels are formed. The clusters are individually insulated from the neighboring cluster, except from the ends, so that the current path through the structured catalyst is a zigzag path. A current of 200 A and a voltage of ca. 5.5 kV are applied to each macroscopic structure of the reactor system of the invention in order to heat the structured catalyst and thus the gas passing over the structured catalyst, corresponding to a power supplied in the structured catalysts of 9899 kW.

[0147] The reactor system in the current configuration could have an overall internal diameter of the reactor system of 3.2 m and a total internal height of 5.5 m when the reactor system is made as a cylindrical reactor system with spherical heads. In this specific configuration, the macroscopic structures are placed in a square orientation having a diagonal length of 2.3 m. In all the examples described herein, except for the comparative example, inert material is placed around the structured catalyst(s) to close the gap to the insulation material, adjacent to the pressure shell. The insulation material in example 1 has a cylindrical form with an internal diameter of 2.5 m and a thickness of 0.35 m.

[0148] During the passage of the feed gas through the reactor system, the feed gas is heated by the structured catalyst and undergoes steam reforming to a product gas having an exit temperature of 963° C.

TABLE-US-00001 TABLE 1 Size of structured catalyst: Edge size [m] 0.53 Height [m] 2.3 Number of macroscopic structures 9 Total volume [L] 5888 Feed gas Product gas T [° C.] 500 963 P [kg/cm.sup.2 g] 27.97 27.47 CO2 [Nm.sup.3/h] 168 727 N2 [Nm.sup.3/h] 26 26 CH4 [Nm.sup.3/h] 2630 164 H2 [Nm.sup.3/h] 590 8545 CO [Nm.sup.3/h] 1 1907 H2O [Nm.sup.3/h] 8046 5022 Total flow [Nm.sup.3/h] 11461 16391 ΔT.sub.app, SMR [° C.] 10 Power [kW] 9899 Heat flux [kW/m.sup.2] 2.2

Example 2

[0149] An example calculation of the process of the invention is given in Table 2 below. A hydrocarbon feed stream comprising i.a. a hydrocarbon gas, hydrogen and steam is fed to the reactor system of the invention. The feed stream entering the reactor system is pressurized to a pressure of 28 kg/cm.sup.2.Math.g and has a temperature of 500° C. Inside the reactor system, a structured catalyst in the form of 1 macroscopic structure having a square cross section is placed which has a size of 0.4 times 0.4 times 0.35 meter. The structured catalyst additionally has 10000 channels with a square cross section having a side or edge length of 0.32 cm. The structured catalyst has slits parallel to the longitudinal direction thereof, so that clusters of 5 times 5 channels are formed. The clusters are individually insulated from the neighboring cluster, except from the ends, so that the current path through the structured catalyst is a zigzag path. A current of 200 A and a voltage of ca. 500 V are applied to the structured catalyst of the reactor system of the invention in order to heat the structured catalyst and thus the gas passing over the structured catalyst, corresponding to a power deposited in the structured catalyst of 99 kW.

[0150] The reactor system in the current configuration could have an overall internal diameter of the reactor system of 1.2 m and a total internal height of 1.5 m when the reactor system is made as a cylindrical reactor system with spherical heads. In this specific configuration, the structured catalyst has a diagonal length of 0.6 m. Inert material is placed around the structured catalysts to close the gap to the insulation material which has an internal diameter of 0.6 m and a thickness of 0.3 m.

[0151] During the passage of the feed gas through the reactor system, the feed gas is heated by the structured catalyst and undergoes steam reforming to a product gas having an exit temperature of 963° C.

TABLE-US-00002 TABLE 2 Size of structured catalyst: Edge size [m] 0.4 Height [m] 0.35 Number of macroscopic structures 1 Total volume [L] 55.4 Feed gas Product gas T [° C.] 500 963 P [kg/cm.sup.2 g] 27.97 27.47 CO2 [Nm.sup.3/h] 1.7 7.3 N2 [Nm.sup.3/h] 0.3 0.3 CH4 [Nm.sup.3/h] 26.3 1.6 H2 [Nm.sup.3/h] 5.9 85.4 CO [Nm.sup.3/h] 0 19.1 H2O [Nm.sup.3/h] 80.5 50.2 Total flow [Nm.sup.3/h] 114.7 163.9 ΔT.sub.app, SMR [° C.] 10 Power [kW] 99 Heat flux [kW/m.sup.2] 2.2

Example 3

[0152] An example calculation of the process of the invention is given in Table 3 below. A hydrocarbon feed stream comprising i.a. a hydrocarbon gas, hydrogen and steam is fed to the reactor system of the invention. The feed stream entering the reactor system is pressurized to a pressure of 97 bar, viz. 97 kg/cm.sup.2.Math.g and has a temperature of 500° C.

[0153] Inside the reactor system, a structured catalyst comprising nine macroscopic structures having a square cross section are placed in an array and each macroscopic structure has a size of 0.53 times 0.53 times 2.3 meter. Each macroscopic structure additionally has 17778 channels with a square cross section having a side or edge length of 0.32 cm. Each macroscopic structure has slits parallel to the longitudinal direction thereof, so that clusters of 5 times 5 channels are formed. The clusters are individually insulated from the neighboring cluster, except from the ends so that the current path through the structured catalyst is a zigzag path. A current of 200 A and a voltage of ca. 5.5 kV are applied to each macroscopic structure in the reactor system of the invention in order to heat the structured catalyst and thus the gas passing over the structured catalyst, corresponding to a power deposited in the structured catalyst of 9899 kW.

[0154] The reactor system in the current configuration could have an overall internal diameter of the reactor system of 3.2 m and a total internal height of 5.5 m when the reactor system is made as a cylindrical reactor system with spherical heads. In this specific configuration, the structured catalysts are placed in a square orientation having a diagonal length of 2.3 m. Inert material is placed around the structured catalysts to close the gap to the insulation material which has an internal diameter of 2.5 m and a thickness of 0.35 m.

[0155] During the passage of the feed gas through the reactor system, the feed gas is heated by the structured catalyst and undergoes steam reforming to a product gas having an exit temperature of 1115° C. It is seen from Table 3 that the total flows of the feed gas and the product gas are lower in Example 3 compared to Example 1.

[0156] Since the product gas exiting the reactor system is pressurized to a pressure of 97 bar, no compressors will be needed downstream the reactor system when a high pressure product gas is requested. This reduces the overall cost of a plant with a reactor system of the invention.

TABLE-US-00003 TABLE 3 Size of structured catalyst: Edge size [m] 0.53 Height [m] 2.3 Number of macroscopic structures 9 Total volume [L] 5888 Feed gas Product gas T [° C.] 500 1115 P [kg/cm.sup.2 g] 96.97 96.47 CO2 [Nm.sup.3/h] 111 510 N2 [Nm.sup.3/h] 23 23 CH4 [Nm.sup.3/h] 2337 143 H2 [Nm.sup.3/h] 372 7354 CO [Nm.sup.3/h] 1 1796 H2O [Nm.sup.3/h] 7111 4518 Total flow [Nm.sup.3/h] 9955 14344 ΔT.sub.app, SMR [° C.] 10 Power [kW] 9899 Heat flux [kW/m.sup.2] 2.2

Example 4

[0157] An example calculation of the process of the invention is given in Table 3 below. A hydrocarbon feed stream comprising i.a. a hydrocarbon gas, hydrogen and steam is fed to the reactor system of the invention. The feed stream entering the reactor system is pressurized to a pressure of 28 bar, viz. 28 kg/cm.sup.2.Math.g and has a temperature of 500° C.

[0158] Inside the reactor system, structured catalyst comprising 25 macroscopic structures having a square cross section are placed in an array and each macroscopic structure has a size of 0.24 times 0.24 times 1.8 meter. Each macroscopic structure additionally has 4702 channels with a square cross section having a side or edge length of 0.33 cm in length. Each macroscopic structure has slits parallel to the longitudinal direction thereof, so that clusters of 10 times 10 channels are formed. The clusters are individually insulated from the neighboring cluster, except from the ends, so that the current path through the structured catalyst is a zigzag path. A current of 500 A and a voltage of ca. 792 V are applied to each macroscopic structure in the reactor system of the invention in order to heat the structured catalyst and thus the gas passing over the structured catalyst, corresponding to a power deposited in the structured catalyst of 9899 kW.

[0159] The reactor system in the current configuration could have an overall internal diameter of the reactor system of 2.3 m and a total internal height of 4.1 m when the reactor system is made as a cylindrical reactor system with spherical heads. In this specific configuration, the structured catalysts are placed in a square orientation having a diagonal length of 1.7 m. Inert material is placed around the structured catalysts to close the gap to the insulation material which has an internal diameter of 1.8 m and a thickness of 0.25 m.

[0160] During the passage of the feed gas through the reactor system, the feed gas is heated by the structured catalyst and undergoes steam reforming to a product gas having an exit temperature of 963° C. It is seen from Table 4 that the structured catalyst of Example 4 is somewhat smaller than the one used in Examples 1 and 3 due to the higher current. The total flows of the feed gas and the product gas correspond to the flows of Example 1.

TABLE-US-00004 TABLE 4 Size of structured catalyst size: Edge size [m] 0.24 Height [m] 1.8 Number of macroscopic structures 25 Total volume [L] 2562 Feed gas Product gas T [° C.] 500 963 P [kg/cm.sup.2 g] 27.97 27.47 CO2 [Nm.sup.3/h] 168 727 N2 [Nm.sup.3/h] 26 26 CH4 [Nm.sup.3/h] 2630 164 H2 [Nm.sup.3/h] 590 8545 CO [Nm.sup.3/h] 1 1907 H2O [Nm.sup.3/h] 8046 5022 Total flow [Nm.sup.3/h] 11461 16391 ΔT.sub.app, SMR [° C.] 10 Power [kW] 9899 Heat flux [kW/m.sup.2] 3.6

Example 5

[0161] An example calculation of the process of the invention is given in Table 4 below. A hydrocarbon feed stream comprising i.a. a hydrocarbon gas, hydrogen and steam is fed to the reactor system of the invention. The feed stream entering the reactor system is pressurized to a pressure of 182 bar and has a temperature of 500° C.

[0162] Inside the reactor system, a structured catalyst comprising nine macroscopic structures having a square cross section are placed in an array and each macroscopic structure has a size of 0.53 times 0.53 times 2.3 meter. Each macroscopic structure additionally has 17778 channels with a square cross section having a side or edge length of 0.32 cm. Each macroscopic structure has slits parallel to the longitudinal direction thereof, so that clusters of 5 times 5 channels are formed. The clusters are individually insulated from the neighboring cluster, except from the ends, so that the current path through the structured catalyst has a zigzag path. A current of 200 A and a voltage of ca. 5.5 kV are applied to each macroscopic structure in the reactor system of the invention in order to heat the structured catalyst and thus the gas passing over the structured catalyst, corresponding to a power deposited in the structured catalyst of 9899 kW.

[0163] The reactor system in the current configuration could have an overall internal diameter of the reactor system of 3.2 m and a total internal height of 5.5 m when the reactor system is made as a cylindrical reactor system with spherical heads. In this specific configuration, the structured catalysts are placed in a square orientation having a diagonal length of 2.3 m. Inert material is placed around the structured catalysts to close the gap to the insulation material which has an internal diameter of 2.5 m and a thickness of 0.35 m.

[0164] During the passage of the feed gas through the reactor system, the feed gas is heated by the structured catalyst and undergoes steam reforming to a product gas having an exit temperature of 1236° C. The total flows of the feed gas and the product gas are lower than the total flows of the gasses in Examples 1 and 4.

[0165] Since the product gas exiting the reactor system is already pressurized to a pressure of 181 bar, it is suited for being input into an ammonia plant without further pressurizing. Thus, no compressors will be needed between the reactor system and the ammonia loop of the ammonia plant. This reduces the overall cost of the plant with a reactor system of the invention and an ammonia loop.

TABLE-US-00005 TABLE 5 Size of structured catalyst size: Edge size [m] 0.53 Height [m] 2.3 Number of macroscopic structures 9 Total volume [L] 5888 Feed gas Product gas T [° C.] 500 1236 P [kg/cm.sup.2 g] 181.97 181 CO2 [Nm.sup.3/h] 86 395 N2 [Nm.sup.3/h] 21 21 CH4 [Nm.sup.3/h] 2116 96 H2 [Nm.sup.3/h] 278 6648 CO [Nm.sup.3/h] 0 1711 H2O [Nm.sup.3/h] 6425 4096 Total flow [Nm.sup.3/h] 8926 12967 ΔT.sub.app, SMR [° C.] 10 Power [kW] 9899 Heat flux [kW/m.sup.2] 2.2

Example 6

[0166] Example 6 relates to a reactor system comprising a structured catalyst in the form of a macroscopic structure having in total 78540 channels with a total wall length of one channel in the cross section of 0.00628 m each and a length of 2 m, giving a total surface area of 987 m.sup.2 of catalyst surface. For a reactor system with this structured catalyst, a simulation with varying gas flow over the structured catalyst was made where the gas composition in all calculations was 8.8% Hz, 56.8% H.sub.2O, 0.2% N.sub.2, 0.1% CO, 2.3% CO.sub.2, and 31.8% CH.sub.4. In each simulation a kinetic model for steam reforming and water gas shift was used and a variation in the surface flux (Q) of energy from the electrically heated structured catalyst was made to adjust the exit temperature of the product gas from the reactor system housing the structured catalyst to 920° C. The kinetic model used was similar to the approach used by Xu and Froment, (J. Xu and G. F. Froment, Methane steam reforming, methanation and water-gas shift: I. intrinsic kinetics. American Institution of Chemical Engineers Journal, 35:88-96, 1989.). FIG. 11 shows the approach to equilibrium along the reactor system length at varying total flows. The Figure shows that at low feed flows (10000 Nm.sup.3/h), the approach to the equilibrium at the outlet the reactor system is below 5° C., which translate into a hydrocarbon conversion of 77%, while at the high flows (150000 Nm.sup.3/h) the approach to equilibrium is above 60° C., which correspond to a hydrocarbon conversion of only 64%, and the hydrocarbons therefore are used less efficiently. The close control of the heat flux in the current invention therefore allows for controlling the approach to equilibrium closely along the length of the reactor system. A general trend in all the curves in FIG. 11 is that the approach to equilibrium is continuously decreasing until a pseudo equilibrium is reached, where the heat added and the heat consumed roughly equal each other. The approach to equilibrium from this stage is substantially constant or has a slightly increasing development due to the overall increasing temperature of the reactor system.

Example 7

[0167] An example calculation of a process of the invention is given in Table 6 below. A hydrocarbon feed stream comprising i.a. a hydrocarbon gas and hydrogen is fed to the reactor system of the invention. The feed stream entering the reactor system is pressurized to a pressure of 3.2 bar, viz. 3.2 kg/cm.sup.2.Math.g, and has a temperature of 500° C.

[0168] Inside the reactor system, a structured catalyst comprising 25 macroscopic structures having a square cross section are placed in an array, where each macroscopic structure has a size of 0.24 times 0.24 times 1.8 meter. Each macroscopic structure additionally has 4702 channels with a square cross section having a side or edge length of 0.33 cm in length. Each macroscopic structure has slits parallel to the longitudinal direction thereof, so that clusters of 10 times 10 channels are formed. The clusters are individually insulated from the neighboring cluster, except from the ends, so that the current path through the structured catalyst is a zigzag path. A current of 500 A and a voltage of ca. 787 V are applied to each macroscopic structure in the reactor system of the invention in order to heat the structured catalyst and thus the gas passing over the structured catalyst, corresponding to a power deposited in the structured catalyst of 9858 kW.

[0169] The reactor system in the current configuration has an overall internal diameter of the reactor system of 2.3 m and a total internal height of 4.1 m when the reactor system is made as a cylindrical reactor system with spherical heads. In this specific configuration, the structured catalyst is placed in a square orientation having a diagonal length of 1.7 m. Inert material is placed around the structured catalyst to close the gap to the insulation material which has an internal diameter of 1.8 m and a thickness of 0.25 m.

[0170] During the passage of the feed gas through the reactor system, the feed gas is heated by the structured catalyst and undergoes propane dehydrogenation and thermal cracking to a product gas having an exit temperature of 600° C.

TABLE-US-00006 TABLE 6 Size of structured catalyst: Edge size [m] 0.24 Height [m] 1.8 Number of macroscopic structures 25 Total volume [L] 2562 Feed gas Product gas T [° C.] 500 600 P [kg/cm.sup.2 g] 3.24 2.73 C.sub.3H.sub.8 [Nm.sup.3/h] 18918 14747 N.sub.2 [Nm.sup.3/h] 0.0 0.0 H.sub.2 [Nm.sup.3/h] 9450 12739 C.sub.3H.sub.6 [Nm.sup.3/h] 0 3721 CH.sub.4 [Nm.sup.3/h] 43 487 C.sub.2H.sub.6 [Nm.sup.3/h] 1338 1767 C.sub.2H.sub.4 [Nm.sup.3/h] 19 33 Total flow [Nm.sup.3/h] 29770 33495.8 ΔT.sub.app, PDH [° C.] Power [kW] 9858 Heat flux [kW/m.sup.2] 3.59