Patent ID: 12214327

DETAILED DESCRIPTION OF THE FIGURES

Throughout the Figures, like reference numbers denote like elements.

FIG.1ashows a cross section through an embodiment of a reactor system100according to the invention. The reactor system100comprises a structured catalyst10, arranged as an array of macroscopic structures5. Each macroscopic structure5in the array is coated with a ceramic coating impregnated with catalytically active material. The reactor system100moreover comprises conductors40,40′ connected to a power supply (not shown in the FIGURES) and to the structured catalyst10, viz. the array of macroscopic structures. The conductors40,40′ are led through the wall of a pressure shell20housing the structured catalyst and through insulating material30on the inner side of the pressure shell, via fittings50. The conductors40′ are connected to the array of macroscopic structures5by conductor contact rails41.

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 conductors40,40′ to conductor contact rails41, and the current runs through the structured catalyst10from one conductor contact rail41, e.g. from the conductor contact rail seen to the left inFIG.1a, to the other conductor contact rail41, e.g. the conductor contact rail seen to the right inFIG.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.

The macroscopic structures5are 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 catalysts5is impregnated with catalytically active material. The conductors40,40′ are made in materials like iron, aluminum, nickel, copper or alloys thereof.

During operating, a feed gas enters the reactor system100from above as indicated by the arrow11and exits the reactor system from the bottom thereof as indicated by the arrow12.

FIG.1bshows the reactor system100ofFIG.1awith a part of the pressure shell20and heat insulation30layer removed andFIG.2is an enlarged view of a part of the reactor system100. InFIGS.1band2the connections between conductors40′ and conductor contact rails41are shown more clearly than inFIG.1a. Moreover, it is seen that the conductors40are led through the walls of the pressure shell in a fitting50, and that the one conductor40is split up into three conductors40′ within the pressure shell. It should be noted, that the number of conductors40′ may be any appropriate number, such as smaller than three or even larger than three.

In the reactor system shown inFIGS.1a,1band2, the conductors40,40′ are led through the wall of a pressure shell20housing the structured catalyst and through insulating material30on the inner side of the pressure shell, via fittings50. Feed gas for steam reforming is inlet into the reactor system100via an inlet in the upper side of the reactor system100as shown by the arrow11, and reformed gas exists the reactor system100via an outlet in the bottom of the reactor system100as shown by the arrow12. Moreover, one or more additional inlets (not shown inFIGS.1ato2) advantageously exist close to or in combination with the fittings50. 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.

In the reactor system100shown inFIGS.1ato2, inert material (not shown inFIGS.1a-2) is advantageously present between the lower side of the structured catalyst10and the bottom of the pressure shell. Moreover, inert material is advantageously present between the outer sides of the structured catalyst10of macroscopic structures5and the insulating material30. Thus, one side of the insulating material30faces the inner side of the pressure shell20and the other side of the insulating material30faces 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 system100and in controlling the flow of the gas through the reactor system100, so that the gas flows over the surfaces of the structured catalyst10.

FIGS.3aand3bshow schematic cross sections through an embodiment of the inventive reactor system100′,100″ comprising a structured catalyst10′. The structured catalyst10′ 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 systems100′,100″ comprises a pressure shell20and a heat insulation layer80between the structured catalyst10′ and the pressure shell20. Inert material90can be used to fill the gap between the structured catalyst10′ and the heat insulation layer or the pressure shell20. InFIGS.3aand3b, the inert material90is indicated by dotted area; the inert material90may be in any appropriate form, e.g. in the form of inert pellets, and it is e.g. of ceramic material. The inert material90assists 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.

FromFIGS.3aand3bit is seen that the reactor systems100′,100″ further comprise an inner tube15in heat exchange relationship with the structured catalyst10′. The inner tube15is adapted to withdraw a product gas from the structured catalyst10′ 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 tube15is electrically insulated from the structured catalyst10′ by either a heat insulation layer80, inert material90, 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 inFIGS.3aand3b, the feed gas enters the reactor system100′,100″ as indicated by the arrow11, and continues into the structured catalyst10′ as indicated by the arrows13. During the passage of the feed gas over the structured catalyst10′, it undergoes the steam reforming reaction. The gas exiting the structured catalyst10′ is at least partly reformed. The at least partly reformed gas flows from the structured catalyst10′ into the inner tube15as indicated by the arrows14, and exits the inner tube as indicated by the arrows12. Even though the heat insulation layer80is present between the inner tube15and the structured catalyst10′, some heat transfer will take place from the gas within the inner tube15and the gas within the structured catalyst10′ or upstream the structured catalyst10′. In the embodiments shown inFIGS.3aand3b, the feed gas flow downwards through the structured catalyst10′ and upwards through the inner tube15; however, it is conceivable that the configuration was turned upside-down so that the feed gas would flow upwards through the structured catalyst10′ and downwards through the inner tube15.

FIGS.4and5show an embodiment of a structured catalyst comprising an array of macroscopic structures as seen from above and from the side, respectively.FIG.4shows a structured catalyst10comprising an array of macroscopic structure5seen from above, viz. as seen from the arrow11inFIGS.1aand1b. The array has 6 rows, viz.1a,1b,1c,1d,1eand1f, of five macroscopic structures5. The macroscopic structures5in 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 rail41. The neighboring macroscopic structure5in a row of macroscopic structures are connected to each other by means of a connection piece3.

FIG.5shows the structured catalyst10having an array of macroscopic structures5ofFIG.4seen from the side. FromFIG.5, it can be seen that each macroscopic structure5extends longitudinally perpendicular to the cross section seen inFIG.4. Each macroscopic structure5has a slit60cut into it along its longitudinal direction (seeFIG.5). Therefore, when energized by the power source, the current enters the array of macroscopic structures5via a conductor contact rail41, is led through the first macroscopic structure5downwards until the lower limit of the slit60and is subsequently led upwards towards a connection piece3. The current is led via a corresponding zigzag path, downwards and upwards, through each macroscopic structure5in each row1a-1fof macroscopic structures5in the array10. This configuration advantageously increases the resistance over the structured catalyst10.

FIG.6shows a structured catalyst10according to the invention in a perspective view. The structured catalyst10comprises a macroscopic structure that is coated with a ceramic coating impregnated with catalytically active material. Within the structured catalyst are channels70extending along the longitudinal direction (shown by the arrow indicate ‘h’ inFIG.6) of the macroscopic structure5; the channels are defined by walls75. In the embodiment shown inFIG.6, the walls75define a number of parallel, square channels70when seen from the direction of flow as indicated by the arrow12. The structured catalyst10has a substantially square perimeter when seen from above, defined by the edge lengths e1and e2. However, the perimeter could also be circular or another shape.

The walls75of the structured catalyst10are 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 catalyst10over which the gas flow flows during operation and interacts with the heated surface of the structured catalyst and the catalytically active material.

Thus, during use in a reactor system for steam reforming, a hydrocarbon feed gas flows through the channels70and interacts with the heated surface of the structured catalyst and with the catalytically active material supported by the ceramic coating.

In the structured catalyst10shown inFIG.6a slit60has been cut into the structured catalyst10. This slit60forces 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 slit60within the macroscopic structure may be provided with embedded insulating material in order to ensure that no current flows in the transverse direction of the slit60.

The channels70in the structured catalyst10are 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 arrows11and12inFIGS.1aand1b, and gets heated via contact with the walls75of the channels70and by heat radiation. The heat initiates the desired steam reforming process. The walls75of the channels70may e.g. have a thickness of 0.5 mm, and the ceramic coating coated onto the walls75may e.g. have a thickness of 0.1 mm. Even though the arrows11and12(seeFIGS.1aand1b) indicate that the flow of the hydrocarbon feed gas is down-flow, the opposite flow direction, viz. an up-flow, is also conceivable.

FIG.7shows the structured catalyst10ofFIGS.1aand1bin a perspective view and with connectors7attached. The connectors7each connects a part of the structured catalyst10to a conductor40. The conductors40are both connected to a power supply (not shown). Each of the connectors7are connected to an upper part of the structured catalyst. When the conductors40are connected to a power supply, an electrical current is led to the corresponding connector7via the conductor and runs through the structured catalyst10. The slit60hinders the current flow in a transverse direction (horizontal direction ofFIG.7) throughout its lengths along the height h of the structured catalyst10. Therefore, the current runs in a direction downwards as seen inFIG.7in the part of the structured catalyst along the slit60, subsequently it runs transversely to the longitudinal direction below the slit60as seen inFIG.7and finally the current runs upwards in the longitudinal direction of the structured catalyst to the other connector7. The connectors7inFIG.7are 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 connectors7are e.g. made in materials like iron, aluminum, nickel, copper or alloys thereof.

As mentioned, the structured catalyst10is coated with a ceramic coating, such as an oxide, supporting the catalytically active material. However, the parts of the structured catalyst10, which are connected to the connectors7, should not be coated with an oxide. Instead, the macroscopic structure of the structured catalyst should be exposed or connected directly to the connectors7in order to obtain a good electrical connection between the macroscopic structure and the connector.

When the connectors7and thus the conductors40are connected to the same end of the structured catalyst10, viz. the upper end as seen inFIG.7, the gas entering into a reactor system housing the structured catalyst10would be able to cool the connectors7and the conductors40. 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 connectors7and conductors40from reaching temperatures much higher than this temperature.

FIG.8shows an alternative embodiment of the structured catalyst10′ with connectors7′ attached. The structured catalyst10′ shown inFIG.8has a square cross section, like the structured catalyst10shown inFIGS.6and7; however, the structured catalyst10′ ofFIG.8does not have any slit cut through it. In the upper and lower end of the macroscopic structure10′ a conductor40. The material of the conductor40is e.g. nickel. Alternatively, other appropriate metals could be used as electrical current distributors, or alloys such as FeCrAlloy. Connectors7′,7″ in the form of electrical conducting bars are used for guiding the current across the structured catalyst10′, i.e. the macroscopic structure. The connectors7′,7″ are fastened to the conductors40and to the structured catalyst10′ by use of mechanical fastening means; however, alternative or additional fastening means are also conceivable.

Connectors7″ at the lower end of the structured catalyst10′ may be made of a different material compared to the connectors7′ at the upper end of the structured catalyst10′ as seen inFIG.2. For example, the connectors7′ may be of cupper, whilst the connectors7″ may be of nickel. Since nickel has a lower conductivity than cupper, the connectors7″ are larger than the connectors7′.

The embodiment shown inFIG.8is suitable for temperatures below 800° C., such as 600-700° C.

FIG.9shows another embodiment of a structured catalyst10′″ with connectors7′″. The structured catalyst10′″ is e.g. the structured catalyst as shown inFIG.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 material61is inside the slit60(seeFIG.6) of the structured catalyst10″.

FIG.10shows 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% CH4, 69.18% H2O, 0.09% Hz, 0.45% CO2, 0.03% Ar, 0.02% CO, 0.15% N2to 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 inFIG.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.

A general trend in all the curves in theFIG.11is 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 Nm3/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

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.

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.

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.

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.

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

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/cm2·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.

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.

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 1Size of structured catalyst:Edge size [m]0.53Height [m]2.3Number of macroscopic structures9Total volume [L]5888Feed gasProduct gasT [° C.]500963P [kg/cm2g]27.9727.47CO2 [Nm3/h]168727N2 [Nm3/h]2626CH4 [Nm3/h]2630164H2 [Nm3/h]5908545CO [Nm3/h]11907H2O [Nm3/h]80465022Total flow [Nm3/h]1146116391ΔTapp, SMR[° C.]10Power [kW]9899Heat flux [kW/m2]2.2

Example 2

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/cm2·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.

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.

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 2Size of structured catalyst:Edge size [m]0.4Height [m]0.35Number of macroscopic structures1Total volume [L]55.4Feed gasProduct gasT [° C.]500963P [kg/cm2g]27.9727.47CO2 [Nm3/h]1.77.3N2 [Nm3/h]0.30.3CH4 [Nm3/h]26.31.6H2 [Nm3/h]5.985.4CO [Nm3/h]019.1H2O [Nm3/h]80.550.2Total flow [Nm3/h]114.7163.9ΔTapp, SMR[° C.]10Power [kW]99Heat flux [kW/m2]2.2

Example 3

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/cm2·g and has a temperature of 500° C.

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.

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.

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.

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 3Size of structured catalyst:Edge size [m]0.53Height [m]2.3Number of macroscopic structures9Total volume [L]5888Feed gasProduct gasT [° C.]5001115P [kg/cm2g]96.9796.47CO2 [Nm3/h]111510N2 [Nm3/h]2323CH4 [Nm3/h]2337143H2 [Nm3/h]3727354CO [Nm3/h]11796H2O [Nm3/h]71114518Total flow [Nm3/h]995514344ΔTapp, SMR[° C.]10Power [kW]9899Heat flux [kW/m2]2.2

Example 4

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/cm2·g and has a temperature of 500° C.

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.

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.

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 4Size of structured catalyst size:Edge size [m]0.24Height [m]1.8Number of macroscopic structures25Total volume [L]2562Feed gasProduct gasT [° C.]500963P [kg/cm2g]27.9727.47CO2 [Nm3/h]168727N2 [Nm3/h]2626CH4 [Nm3/h]2630164H2 [Nm3/h]5908545CO [Nm3/h]11907H2O [Nm3/h]80465022Total flow [Nm3/h]1146116391ΔTapp, SMR[° C.]10Power [kW]9899Heat flux [kW/m2]3.6

Example 5

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.

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.

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.

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.

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 5Size of structured catalyst size:Edge size [m]0.53Height [m]2.3Number of macroscopic structures9Total volume [L]5888Feed gasProduct gasT [° C.]5001236P [kg/cm2g]181.97181CO2 [Nm3/h]86395N2 [Nm3/h]2121CH4 [Nm3/h]211696H2 [Nm3/h]2786648CO [Nm3/h]01711H2O [Nm3/h]64254096Total flow [Nm3/h]892612967ΔTapp, SMR[° C.]10Power [kW]9899Heat flux [kW/m2]2.2

Example 6

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 m2of 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% H2O, 0.2% N2, 0.1% CO, 2.3% CO2, and 31.8% CH4. 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.11shows the approach to equilibrium along the reactor system length at varying total flows. The Figure shows that at low feed flows (10000 Nm3/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 Nm3/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 inFIG.11is 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

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/cm2·g, and has a temperature of 500° C.

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.

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.

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 6Size of structured catalyst:Edge size [m]0.24Height [m]1.8Number of macroscopic structures25Total volume [L]2562Feed gasProduct gasT [° C.]500600P [kg/cm2g]3.242.73C3H8[Nm3/h]1891814747N2[Nm3/h]0.00.0H2[Nm3/h]945012739C3H6[Nm3/h]03721CH4[Nm3/h]43487C2H6[Nm3/h]13381767C2H4[Nm3/h]1933Total flow [Nm3/h]2977033495.8ΔTapp, PDH[° C.]Power [kW]9858Heat flux [kW/m2]3.59