Apparatus and method for ammonia cracking catalyst activation

Abstract

An apparatus and method for catalyst material activation for use in ammonia cracking may include an initial stage of initial use of hydrogen and heat for catalyst activation, and a subsequent state of subsequent use of ammonia and heat for catalyst activation. The subsequent use of ammonia may be configured such that different catalytic materials at different device elements are activated in a preselected order to provide activation of the catalytic materials used in different device elements. Some embodiments may be configured to avoid excess temperatures that may be detrimental to equipment that may be positioned upstream of the furnace in some embodiments, while also avoiding sintering of the catalytic material.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 596,320 filed on November 6, 2023. Technical Field

[0003] The present invention relates to a method and apparatus for activation of catalyst materials used in an ammonia cracking plant and process. Background Art

[0004] Ammonia can be cracked to produce hydrogen. Examples of methods that can be used to crack ammonia can be learned from U.S. Patent Application Publication No. 2023 / 0242395 and International Publication Nos. WO2022 / 265647, WO2022 / 265648, WO2022 / 265649, WO2022 / 265650, WO2022 / 265651 and pending U.S. Patent Application Nos. 17 / 990,832, 17 / 990,823, 17 / 990,817 and 17 / 990,815. Summary of the invention

[0005] The ammonia cracking process may involve the use of catalyst materials to help promote the cracking of ammonia into hydrogen and nitrogen. Catalyst activation may depend on the catalyst formulation. Activation is usually started at some low temperature and processed to a higher final temperature. The final temperature usually depends on the active metal species on the catalyst. For example, ruthenium (Ru) catalysts usually use a lower final activation temperature (e.g., less than 350°C), and nickel (Ni) catalysts usually require a higher final activation temperature (e.g., greater than 350°C). Compared with Ni catalysts, Ru catalysts can also have more stringent requirements on the temperature rise and holding time of catalyst activation.

[0006] "Andrew, SP (1981), Theory and practice of the formulation of heterogeneous catalysts. Chemical Engineering Science, 36 (9), 1431-1445" discloses that activation of catalyst materials may involve a combination of subjecting the catalyst material to a higher temperature environment (e.g., application of heat) and exposure to a reducing agent. "Twigg, MV (1996). Catalyst Handbook (2nd ed.). London: Manson Publishing Ltd. ("Twigg")" discloses that hydrogen is a commonly used reducing agent. Twigg also discloses that a catalyst activation method is performed to reduce a precursor metal oxide of a supported metal catalyst into fine crystals of a metal catalyst, whereby the catalyst is activated and is able to provide a reduction in activation energy or a change in reaction mechanism, which can help promote a chemical reaction.

[0007] We have determined that the catalyst for ammonia cracking can be shipped in an oxidized state, a semi-oxidized state, or an at least partially passivated state, which may require activation prior to use in ammonia cracking. As described above, activation of the catalytic material can include using a method of exposing the catalyst material to a reducing environment, such as activating the catalytic material with a hydrogen-containing gas and heat (e.g., removing oxides, removing an oxide layer surrounding or covering an internal catalytic metal material, removing a passivation layer surrounding or covering an internal catalytic metal material, etc.). Conventionally, activation will be performed using hydrogen mixed with an inert gas such as nitrogen (see, for example, Twigg, MV (1996). Catalyst Handbook (2nd ed.). London: Manson Publishing Ltd.).

[0008] However, we have determined that activation of catalyst materials that may be located in a furnace for cracking ammonia (e.g., tubes located in a furnace through which ammonia may pass to be heated and cracked therein to form hydrogen (H2) and nitrogen (N2)) may require very high temperatures (e.g., temperatures in excess of 500°C or in excess of 600°C (e.g., between 450°C and 700°C, between 550°C and 675°C, between 500°C and 700°C, etc.). We have determined that such high temperatures within the furnace during an extended catalyst activation process may cause some types of front-end heat exchangers disclosed in U.S. Patent Application Nos. 17 / 990,823, 17 / 990,817, and 17 / 990,815 to exceed their design temperatures unless those heat exchangers are made of special materials that can withstand very high temperatures since the reductant and heat may be recycled through the reactor and furnace to activate the catalyst materials. However, utilizing such specialized equipment may be disadvantageous to the procurement of such equipment and may also result in increased costs and production or installation delays as well as special maintenance work and / or higher maintenance costs.

[0009] For example, the use of more specialized equipment may introduce increased safety risks because more exotic metals or equipment grades may introduce more items that require maintenance supervision and maintenance monitoring. Avoiding or minimizing their use can help avoid this increased safety risk, and utilizing these types of additional maintenance activities to address this increased risk.

[0010] We have determined that such high temperature profiles for catalyst activation within an ammonia cracking plant configured to implement an ammonia cracking process can be avoided, allowing for the use of lower temperature rated front-end equipment. We have determined that such features can help provide improved catalyst material activation while also providing improved operating efficiency and flexibility. We believe that embodiments can also help make ammonia cracking more economically attractive by using more environmentally friendly ammonia products (e.g., ammonia produced by renewable power sources and / or ammonia produced in conjunction with carbon dioxide capture technology), thereby also achieving environmentally friendly ammonia production and an increase in ammonia cracking for hydrogen production.

[0011] In some embodiments, the method and apparatus for catalyst activation of an ammonia cracking device may include using hydrogen as a reactant and heating by a furnace to perform an initial first lower temperature stage of catalyst activation within a first catalyst activation time period. In some specific implementations, the initial first lower temperature activation may include periodically increasing the temperature and / or hydrogen concentration until the first stage of catalyst activation is satisfied. After the first initial stage of catalyst activation is detected to have occurred, a second higher temperature stage of catalyst activation may be performed within a second catalyst activation time period. The second stage may include using ammonia as a reactant and using a higher second temperature curve. Before or during the use of ammonia as a reactant in the second higher temperature stage of catalyst activation and / or after such discharge occurs, the second stage may occur in combination with the discharge of hydrogen reactant fluid to remove the hydrogen reactant fluid. In some embodiments, the second stage of the higher temperature stage of catalyst activation may occur sequentially after the first stage, so that the second stage begins to occur immediately after the first initial lower temperature stage has been completed (e.g., the second higher temperature stage may begin to occur immediately and directly after the first stage has been completed by detecting a specific temperature and / or hydrogen content associated with the completion of the initial lower temperature first stage of the catalyst activation method).

[0012] In some embodiments, the method may be implemented to help control the temperature within a unit of an ammonia cracking process such that the furnace experiences a maximum temperature and the upstream reactor upstream of the furnace and the heat exchanger upstream of the furnace experience lower temperatures within a preselected temperature profile to help avoid exposing the equipment to temperatures above what the equipment is rated to experience (e.g., the temperature may not exceed 350°C, may be between 300°C and 400°C, the temperature may not exceed 550°C, etc.). For example, some heat exchangers may have different temperature ratings, and the temperature control that may be provided by the embodiment catalyst activation process and the equipment configured to utilize this method may be configured to keep different heat exchanger equipment within their temperature ratings. In some embodiments, such temperature ratings may vary from 200°C to 690°C for different heat exchangers (e.g., one or more preheat heat exchangers may have a temperature rating in the range of 200°C to 325°C, while one or more other heat exchangers have a temperature rating in the range of 325°C to 690°C).

[0013] In some implementations, the catalyst activation provided may result in the catalyst material in the upstream portion of the furnace being activated first, and then the catalyst material of the second reactor being activated second, even if the second reactor is between the first reactor and the furnace. The catalyst activation provided may then also result in the activation of the catalyst material of the first reactor, and finally, the catalyst material in the downstream portion of the furnace being activated last. We have found that this type of staged activation can help avoid high temperature profiles in the upstream reactor and the upstream heat exchanger, while also helping to provide a sufficiently timed catalyst activation method, which can also help avoid sintering of the catalyst material.

[0014] We have surprisingly found that using ammonia as a reactant in the second higher temperature stage of catalyst activation can help keep the front end heat exchanger within the lower standard design temperature. In some embodiments, the ammonia used in the second higher temperature stage of catalyst activation can be blended with nitrogen or used in pure form. It is expected that nitrogen (N2) can be injected for mixing with ammonia to provide a desired flow rate to obtain a preselected flow rate of the second reactant and a preselected concentration of ammonia in the second reactant as the second reactant passes through the tubes of the pre-reactor and the furnace containing the catalyst material.

[0015] We have discovered that the use of ammonia (NH3) during catalyst activation can also provide a cooling source for the entire system (e.g., the sensible heat, latent heat, endothermic reaction of ammonia cracking to form nitrogen and hydrogen during the catalyst activation process involving ammonia as a reactant can provide a cooling effect, etc.), which can also reduce the need for other cooling media / equipment during catalyst activation (e.g., cooling water tower or air cooler load savings, etc.).

[0016] In some embodiments, the ammonia feed rate used during catalyst activation can be significantly lower than the design rate for ammonia cracking to produce hydrogen after the catalyst material is activated. In addition, a higher amount of conversion can occur on the upstream reactor during catalyst activation. Since most of the ammonia can be used in the second stage of catalyst activation, so that ammonia is converted in the upstream pre-reactor during the higher temperature second stage of catalyst activation, the temperature in the furnace downstream of those reactors can be quickly increased to the desired activation temperature because during the catalyst activation process, the heat absorption from the ammonia cracking reaction is little to significantly less (or in some cases no heat absorption) consuming the heat generated by the burner of the furnace. We surprisingly found that this effect can lead to improved catalyst activation that can also occur faster (for example, the activation process can occur faster to allow catalyst activation to occur more flexibly, efficiently and quickly because the downtime associated with the catalyst activation for the ammonia cracking process can be less).

[0017] We have also discovered that embodiments may allow the use of some catalyst materials having significantly higher final activation temperatures in combination with other catalyst materials having lower final activation temperatures. For example, in some embodiments, catalyst materials having an activation temperature in excess of 600°C (e.g., 650°C, between 600°C and 700°C, etc.) may be used in combination with other catalyst materials having a full activation temperature of no more than 400°C, no more than 350°C, or a temperature between 300°C and 400°C.

[0018] In a first aspect, a method for catalyst activation for ammonia cracking may include feeding a first reactant comprising hydrogen to at least one pre-reactor positioned upstream of a furnace having at least one tube within a radiant section of the furnace such that the first reactant passes through catalyst material of the at least one pre-reactor and subsequently passes through catalyst material of the at least one tube within the radiant section of the furnace. In response to detecting a first level of catalyst activation, feeding the first reactant may be stopped and feeding a second reactant comprising ammonia to the at least one pre-reactor and the at least one tube within the radiant section of the furnace may be started such that the second reactant passes through catalyst material of the at least one pre-reactor and subsequently passes through the at least one tube within the radiant section of the furnace to fully activate the catalyst material of the at least one tube.

[0019] In some embodiments, the hydrogen concentration in the first reactant can be controlled within a preselected concentration range. For example, the first reactant can include a mixture of nitrogen and hydrogen, and the hydrogen concentration can be within a range of 10 mole percent (mol%) and 20 mol% or within a range greater than 0 mol% and less than or equal to 25 mol%. The hydrogen concentration can be adjusted during the first stage of catalyst activation so that it is adjusted over time within a preselected suitable concentration range.

[0020] In addition, the ammonia concentration in the second reactant can be controlled within a preselected concentration range. For example, the second reactant can include a mixture of nitrogen and ammonia, and the ammonia concentration can be within a range of 10 moles (mol%) and 20mol% or greater than 0mol% and less than or equal to 25mol%. The ammonia concentration can be regulated during the second stage of catalyst activation so that it is regulated over time within a preselected suitable concentration range. In addition, when ammonia is used for the second stage of catalyst activation, hydrogen and nitrogen can be formed during the activation process and can exist together with the ammonia and nitrogen of the second reactant.

[0021] In some embodiments, the first level of catalyst activation can be determined based on a preselected set of criteria. The criteria can include a temperature profile and / or concentration profile of hydrogen. The criteria can also (or alternatively) include a preselected time period.

[0022] In a second aspect, the feed of the first reactant and the feed of the second reactant can occur such that the catalyst material in the upstream portion of the at least one tube is fully activated, then the catalyst material of the at least one pre-reactor is fully activated, and then after the catalyst material of the at least one pre-reactor is fully activated and after the catalyst material in the upstream portion of the at least one tube is fully activated, the catalyst material in the downstream portion of the at least one tube is fully activated. In other embodiments, the method can be implemented such that other activation sequences of different catalyst materials can occur alternatively.

[0023] In a third aspect, the feeding of the second reactant comprising ammonia can occur such that the catalyst material in the downstream portion of the at least one tube is fully activated last. For example, the catalyst material in the downstream portion of the at least one tube can include iron (Fe) and / or nickel (Ni) and can be activated last after the upstream layer of the catalyst material comprising ruthenium (Ru) in the tubes of the furnace and the one or more pre-reactors has been activated.

[0024] In a fourth aspect, the method may include mixing nitrogen with the ammonia of the second reactant such that the second reactant has a preselected ammonia concentration of ammonia and / or the second reactant has a preselected flow rate.

[0025] In a fifth aspect, a method may include mixing nitrogen with hydrogen of the first reactant such that the first reactant has a preselected hydrogen concentration of hydrogen and / or the first reactant has a preselected flow rate.

[0026] In a sixth aspect, the at least one prereactor may include a plurality of prereactors including a first prereactor and a second prereactor. The first prereactor may have a catalyst material within a vessel of the first prereactor and the second prereactor may have a catalyst material within a vessel of the second prereactor. The second prereactor may be downstream of the first prereactor such that the second prereactor is between the at least one tube of the furnace and the first prereactor.

[0027] The feeding of the first reactant may occur such that: (a) the catalyst material in the upstream portion of at least one tube is fully activated, (b) the catalyst material of the second pre-reactor is fully activated; and (c) the catalyst material of the first pre-reactor is fully activated. The feeding of the second reactant may occur such that (d) the catalyst material in the downstream portion of at least one tube is fully activated. In some embodiments, the catalyst material of the downstream portion of at least one tube may have a higher activation temperature than the catalyst material of the upstream portion of at least one tube. In some embodiments, the catalyst material of the downstream portion of at least one tube may also have a higher activation temperature than the catalyst material of the first pre-reactor. The catalyst material of the downstream portion of at least one tube may also have a higher activation temperature than at least some of the catalyst materials of the second pre-reactor.

[0028] In a seventh aspect, the feeding of the first reactant may further include recirculating the first reactant through at least one tube and at least one pre-reactor for a first period of time. For example, the first period of time may be a first period of time of a first stage of catalyst activation. The first period of time may be a preselected period of time defined by a preselected set of design criteria.

[0029] In an eighth aspect, the method may further include, in response to detecting a first level of catalyst activation, discharging the first reactant while the second reactant begins to be fed toward at least one pre-reactor and at least one tube. Discharging may also be provided so that the second reactant output from at least one tube during the second stage of the catalyst activation process is also discharged (e.g., not recycled).

[0030] In a ninth aspect, the method of the first aspect may include one or more features of the second aspect, the third aspect, the fourth aspect, the fifth aspect, the sixth aspect, the seventh aspect, and / or the eighth aspect to provide other embodiments. In addition, other features may be utilized in embodiments of the method. Examples of such other features are discussed in conjunction with the exemplary embodiments of the method provided herein.

[0031] In a tenth aspect, a device for ammonia cracking is provided, the device being configured to promote catalyst activation. Embodiments of the device may be configured to utilize embodiments of a method for catalyst activation for ammonia cracking. The device may include a furnace having at least one tube, which includes a catalyst material for ammonia cracking in at least one tube. The catalyst material in at least one tube may have an upstream portion of the catalyst material and a downstream portion of the catalyst material. At least one pre-reactor may be positioned upstream of at least one tube. At least one tube may be in fluid communication with at least one pre-reactor. The device may be sized and configured so that a first reactant may be fed to at least one pre-reactor and at least one tube, so that the first reactant passes through the catalyst material of at least one pre-reactor and then passes through the catalyst material of at least one tube. In addition, the device may be sized and configured so that a second reactant may be fed to at least one pre-reactor and at least one tube, so that in response to detecting a first level of catalyst activation, the first reactant is dischargeable and the second reactant may be fed to at least one pre-reactor and at least one tube, so that the second reactant may pass through the catalyst material of at least one pre-reactor and then pass through at least one tube to fully activate at least some of the catalyst material of at least one tube.

[0032] Embodiments of the apparatus may also include other elements and features. For example, embodiments may include a plurality of heat exchangers positioned upstream of the pre-reactor and / or one or more heat exchangers positioned between the pre-reactor and at least one tube of the furnace. As another example, embodiments may utilize pumps and / or compressors to facilitate the flow of fluid.

[0033] In the eleventh aspect, the apparatus may be configured such that the feeding of the first reactant occurs such that the upstream portion of the catalyst material of the at least one tube is fully activated first, and then the catalyst material of the at least one pre-reactor is fully activated. The second reactant may also be fed to the at least one tube and the at least one pre-reactor such that after the catalyst material of the at least one pre-reactor is fully activated and after the upstream portion of the catalyst material of the at least one tube is fully activated, the downstream portion of the catalyst material of the at least one tube is fully activated. For example, in some embodiments, the apparatus may be configured such that the feeding of the second reactant occurs such that the downstream portion of the catalyst material of the at least one tube is fully activated last.

[0034] In the twelfth aspect, at least one pre-reactor of the device may include a plurality of pre-reactors. The plurality of pre-reactors may include a first pre-reactor having a catalyst material in a container of the first pre-reactor and a second pre-reactor having a catalyst material in a container of the second pre-reactor. The second pre-reactor may be downstream of the first pre-reactor so that the second pre-reactor is between at least one tube of the furnace and the first pre-reactor. The device may be configured so that the feeding of the first reactant occurs so that (a) the upstream portion of the catalyst material of at least one tube is fully activated, (b) the catalyst material of the second pre-reactor is fully activated, and (c) the catalyst material of the first pre-reactor is fully activated. The feeding of the second reactant may also occur so that (d) the catalyst material in the downstream portion of the catalyst material of at least one tube is fully activated. The downstream portion of the catalyst material of at least one tube may have a higher activation temperature than the catalyst material of the upstream portion of the catalyst material of at least one tube. The downstream portion of the catalyst material of at least one tube may also have a higher activation temperature than the catalyst material of the first pre-reactor, and the catalyst material of the downstream portion of at least one tube may also have a higher activation temperature than at least some of the catalyst materials of the second pre-reactor.

[0035] In a thirteenth aspect, the apparatus may include a reactant recirculation conduit arrangement positioned so that the first reactant can be recirculated from the outlet of the at least one tube to the at least one pre-reactor. In some embodiments, the reactant recirculation conduit may be positioned and configured so that a compressor can receive some of the first reactant output from the at least one tube to compress it for recirculating the first reactant back to the at least one tube of the pre-reactor and the furnace.

[0036] In a fourteenth aspect, a device for ammonia cracking configured to promote catalyst activation may include a furnace having at least one tube, including a catalyst material for ammonia cracking in at least one tube, wherein the catalyst material in at least one tube has a higher activity portion of the catalyst material that is more active than a lower activity portion of the catalyst material. At least one pre-reactor may be positioned upstream of at least one tube, wherein at least one tube may be in fluid communication with at least one pre-reactor. The device may be sized and configured so that a first reactant may be fed to at least one pre-reactor and at least one tube, so that the first reactant passes through the catalyst material of at least one pre-reactor and then passes through the catalyst material of at least one tube. A second reactant may also be fed to at least one pre-reactor and at least one tube, so that in response to detecting a first level of catalyst activation, the first reactant is dischargeable and the second reactant may be fed to at least one pre-reactor and at least one tube, so that the second reactant may pass through the catalyst material of at least one pre-reactor and then pass through at least one tube to fully activate the lower activity portion of the catalyst material of at least one tube. Embodiments of the device may also include other features (e.g., a recirculation conduit, a heat exchanger, etc.).

[0037] In the fifteenth aspect, the device of the tenth aspect or the device of the fourteenth aspect may include one or more other features of the eleventh aspect, the twelfth aspect, and / or the thirteenth aspect to provide other embodiments. In addition, other features may be utilized in embodiments of the device. Examples of such other features are discussed in conjunction with the exemplary embodiments of the devices provided herein.

[0038] In other embodiments of the apparatus and method, it is contemplated that a single reactant containing only ammonia (e.g., ammonia, ammonia mixed with nitrogen, etc.) may be used for catalyst activation. The ammonia used may be liquid ammonia, which is vaporized, optionally mixed with nitrogen, and subsequently passed through a pre-reactor and at least one tube having catalyst material therein and positioned in the radiant section of the furnace for activation of the catalyst material. Catalyst material activation may occur within a pre-selected time period according to a pre-selected activation scheme to provide complete activation of all catalyst materials within the temperature ratings of various equipment. This activation may be provided by the use of at least some recirculation of ammonia, while also adding additional liquid ammonia to the reactant feed to provide catalyst activation, and also controlling the temperatures at different pre-reactors / furnace tubes and heat exchangers to provide a catalyst activation sequence, so that the catalyst material with the highest activation temperature in the tubes of the furnace is activated last, while other catalyst materials are activated before the highest activation temperature catalyst material in the tubes of the furnace.

[0039] It should be appreciated that embodiments of the method and apparatus may utilize a variety of conduit arrangements and process control elements. Embodiments may utilize sensors (e.g., pressure sensors, temperature sensors, flow rate sensors, concentration sensors, etc.), controllers, valves, piping, and other process control elements. For example, some embodiments may utilize automated process control systems and / or distributed control systems (DCS). A variety of different conduit arrangements and process control systems may be utilized to meet a particular set of design criteria.

[0040] Other details, objects and advantages of our apparatus for activating catalyst materials used in ammonia cracking, method for activating catalyst materials used in ammonia cracking, and methods for making and using the same will become apparent as certain exemplary embodiments thereof are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Exemplary embodiments of our apparatus for activating catalyst materials used in ammonia cracking, methods for activating catalyst materials used in ammonia cracking, and methods of making and using the same are shown in the accompanying drawings. It should be understood that reference numerals used in the drawings may identify the same components.

[0042] Figure 1 is a block diagram of a first exemplary embodiment of an apparatus configured for ammonia cracking, which is also configured for activation of catalyst materials used in ammonia cracking. Figure 1 Exemplary embodiments of methods for activation of catalyst materials used in ammonia cracking may also be appreciated;

[0043] Figure 2 is a flow chart showing an exemplary embodiment of a method for activation of catalyst materials used in ammonia cracking. A First Exemplary Embodiment of an Apparatus for Activation of Catalyst Materials Used in Ammonia Cracking This first exemplary embodiment of the method may be implemented. DETAILED DESCRIPTION

[0044] refer to Figure 1-2 , a device 1 configured for ammonia cracking may include a plurality of processing elements to receive ammonia (NH 3 ) and crack the ammonia to produce hydrogen and nitrogen. The hydrogen formed may then be separated from the nitrogen to produce a hydrogen gas stream 40 .

[0045] For example, the liquid ammonia feed 2 may be maintained in a storage device (e.g., at least one ammonia storage tank) at an ammonia storage temperature (e.g., -32°C, between -25°C and -40°C, etc.). The stored ammonia, which may be stored as liquid ammonia, may be removed from the storage device and fed to a pump P101, where it is pumped to produce a pressurized liquid ammonia stream 4 at a preselected feed pressure (e.g., 4.6 MPa, 4 MPa to 5 MPa, or other suitable feed pressure within a preselected feed pressure range). The pressurized feed stream may be fed to a preheating heat exchanger E271 that may preheat the pressurized ammonia feed to produce a preheated liquid ammonia stream 6.

[0046] In some embodiments, the preheating heat exchanger E271 can utilize a heat transfer fluid, which can be any suitable type of heat transfer fluid for preheating liquid ammonia to a preselected preheating temperature (e.g., a temperature between 40° C. and 60° C., a temperature of 45° C., etc.). In some embodiments, the heat transfer fluid can be or include a glycol (e.g., a fluid having 55% by weight ethylene glycol or propylene glycol). The preheating heat exchanger E271 can alternatively be (or also include) an electric heater to help ensure that the temperature of the heat transfer fluid fed to the heat exchanger E271 as a heating medium is at a temperature sufficient to preheat the liquid ammonia to the desired temperature.

[0047] The preheated feed stream 6 may undergo further preheating to further heat and vaporize the ammonia feed by other preheating heat exchangers. One or more other preheating heat exchangers may be utilized, such as heat exchangers E312, E311, E310, and E2102.

[0048] For example, the initial preheated ammonia feed stream 6 output from heat exchanger E271 can be further heated by heat exchange in heat exchanger E312 to produce a stream 8 of further heated liquid ammonia. The further heated liquid ammonia in stream 8 can then be vaporized by heat exchange in heat exchanger E311 to produce a stream 10 of gaseous ammonia or ammonia vapor. The ammonia vapor in stream 10 can then be superheated by heat exchange in heat exchanger E310 to produce a heated ammonia gas stream 12 at a preselected preheated ammonia temperature (e.g., a temperature of 260° C., a temperature between 240° C. and 280° C., etc.).

[0049] The heated ammonia in stream 12 may then be further heated by heat exchange in heat exchanger E2102 to produce a superheated ammonia gas stream 14 at a preselected superheated ammonia temperature (eg, a temperature of 420°C, a temperature between 400°C and 450°C, etc.).

[0050] In conjunction with providing such preheating of ammonia, each heat exchanger E310, E311, E312, and E2102 may have a preselected temperature rating that is specified to take into account the preheating conditions that a particular heat exchanger may be expected to experience during ammonia cracking operations and the availability of equipment that can meet these conditions. For example, heat exchanger E312 may have a temperature rating between 100°C and 300°C, heat exchanger E311 may have a temperature rating between 175°C and 450°C, heat exchanger E310 may have a temperature rating between 330°C and 570°C, and heat exchanger E2102 may have a temperature rating between 300°C and 500°C. Other embodiments may utilize other temperature profiles and other heat exchangers having other suitable temperature ratings.

[0051] In some embodiments, there may be a single heat exchanger E2102 for providing superheated ammonia. In other embodiments, heat exchanger E2102 may output a heated ammonia gas stream for feeding to at least one other feed preheating heat exchanger to produce a superheated ammonia gas stream 14. In some embodiments, there may also be at least one selective catalytic reactor (SCR) located between heat exchanger E2102 and a second feed preheating heat exchanger downstream of heat exchanger E2102 or within a heat exchanger (e.g., within heat exchanger E2102). In some embodiments, the heat transfer fluid that can be used as a heating medium for heat exchanger E2102 and / or other heat exchangers can be flue gas output from furnace F201 of apparatus 1.

[0052] Other embodiments may utilize different arrangements of preheat heat exchangers to produce the superheated ammonia of stream 14. For example, fewer or more heat exchangers may be used to provide the formation of superheated ammonia. The heat transfer fluid used for such heating may be any suitable heat transfer fluid that may be used as a suitable heating medium for heating ammonia to form the superheated ammonia of stream 14.

[0053] The superheated ammonia in stream 14 can be fed to one or more pre-reactors upstream of furnace F201. The superheated ammonia gas stream feed temperature for feeding to the one or more pre-reactors can be a preselected superheated ammonia gas feed temperature (e.g., a temperature of 420°C, a temperature between 400°C and 500°C, a temperature between 400°C and 450°C, etc.). The superheated ammonia gas stream feed pressure can be a suitable preselected feed pressure, which can be less than the pressure of stream 4 at which pump P101 outputs pressurized liquid ammonia. For example, the preselected feed pressure of the superheated ammonia to be fed to the one or more pre-reactors can be 4.3 MPa, between 4 MPa and 4.5 MPa, or other suitable pressures.

[0054] The upstream pre-reactor may include a first adiabatic reactor C141 or a first pre-reactor C141, which may have a catalyst bed in the container of the reactor. The catalyst bed may include a suitable catalyst material. For example, the catalyst material of the catalyst bed of the first adiabatic reactor C141 may be a ruthenium-based catalyst bed or may be a nickel-based catalyst bed. Other embodiments may alternatively use the first pre-reactor C141, which may utilize other catalyst materials or combinations of catalyst materials (e.g., an iron-based catalyst material bed, a catalyst material bed having a combination of nickel and iron catalyst materials, a catalyst material including an upstream layer of a catalyst material and a combination of downstream layers of different catalyst materials, etc.).

[0055] When passing through the catalyst bed of the first pre-reactor C141, some of the ammonia can be cracked to form a first pre-reactor output stream 16 of intermediate gas, which includes ammonia and some products of partially cracked ammonia (e.g., nitrogen and hydrogen). In some embodiments, the mole fraction of ammonia in the gas passing through the first adiabatic reactor vessel C141 can drop from about 100 mole percent (mol%) ammonia to about 90 mol% ammonia (e.g., about 10% of the ammonia can be cracked when it passes through the first pre-reactor C141). In other embodiments, the mole fraction of ammonia can be different (e.g., it can be between 95 mol% and 90 mol% ammonia or between 95 mol% and 80 mol%, etc.).

[0056] The first pre-reactor output stream 16 of the intermediate gas can be output at a preselected temperature. The temperature can be, for example, about 360° C., between 320° C. and 380° C., or another suitable temperature. The intermediate stream can then be fed to a second pre-reactor C142, which can be, for example, a second adiabatic reactor C142.

[0057] In some embodiments, the first pre-reactor output stream 16 of the intermediate gas can be heated by a heat exchanger E2103 to produce a stream 18 of superheated intermediate gas before it is fed to the second adiabatic reactor C142, which can also be another type of second pre-reactor. For example, the first pre-reactor output stream 16 of the intermediate gas can be heated to a preselected second pre-reactor feed temperature by passing through a heat exchanger E2103 before it is fed to the second adiabatic reactor C142. The second preselected second pre-reactor feed temperature can be, for example, a feed temperature of 590°C, between 450°C and 610°C, between 550°C and 620°C, or other suitable temperatures. The intermediate gas preheating heat exchanger E2103 can provide the desired preheating using a suitable heat transfer fluid (e.g., waste gas or flue gas from furnace F201 or other heating medium).

[0058] The stream 18 of superheated intermediate gas can be fed to the second pre-reactor C142 (e.g., the second adiabatic reactor C142). The second pre-reactor may also include a container having a bed including a catalyst material. The catalyst material of the second pre-reactor C142 may be the same catalyst material as the first pre-reactor or include catalyst materials arranged differently. For example, the second pre-reactor C142 may have a catalyst material bed including a nickel-based catalyst upstream layer and a ruthenium-based catalyst downstream layer. Other embodiments may alternatively use different combinations or catalyst materials or a single type of catalyst material bed. For example, in some embodiments, the second pre-reactor C142 may utilize a catalyst material bed including only an iron-based catalyst, only a ruthenium-based catalyst, or a combination of a nickel-based catalyst and / or an iron-based catalyst downstream layer and a ruthenium-based catalyst upstream layer.

[0059] The superheated intermediate gas can be passed through a second pre-reactor for additional pre-cracking of the ammonia of the intermediate gas to produce a furnace feed stream 20 of partially cracked ammonia. The mole fraction of ammonia in the gas output from the second pre-reactor C142 can be a pre-selected furnace feed concentration. For example, the mole fraction of ammonia in the furnace feed stream 20 can be 0.6 (e.g., 60 mol% ammonia), or can be between 55 mol% ammonia and 75 mol% ammonia.

[0060] In the case where a ruthenium-based catalyst is used in both the first and second pre-reactors C141 and C142, the same type of catalyst may be used in both reactors, or different ruthenium-based catalysts may be used. The type of catalyst material utilized in the first and second pre-reactors may also be adapted to take into account different design criteria or operational objectives. In some embodiments, the catalyst bed of the first pre-reactor C141 may be configured to provide a lower level of ammonia cracking compared to the catalyst bed of the second pre-reactor C142 positioned downstream of the first pre-reactor C141 and upstream of the furnace F201.

[0061] In some configurations, at least one of the pre-reactors may utilize a lower activity catalyst having a lower activity in promoting ammonia cracking than a higher activity catalyst having a higher activity in promoting ammonia cracking. For example, a ruthenium-based catalyst may be the higher activity catalyst, and a nickel-based catalyst or an iron-based catalyst may be the lower activity catalyst. The lower activity catalyst may also have a higher full activation temperature than the more active catalyst.

[0062] In other embodiments, there may be only a single pre-reactor (e.g., only pre-reactor C141 or C142). In such embodiments, the operating temperature of the single pre-reactor, the catalyst material used in the pre-reactor, and the size of the pre-reactor may be adjusted to take into account its use in providing a feed of partially cracked ammonia as a furnace feed stream 20 for further cracking in one or more tubes of furnace F201. In such a configuration, the superheated ammonia gas stream feed temperature for feeding to the pre-reactor may be a preselected superheated ammonia feed temperature, which may be higher than the temperature that may be selected for use in an arrangement with multiple pre-reactors (e.g., a temperature between 450°C and 550°C, a temperature between 475°C and 600°C, etc.) for processing ammonia therein to output partially cracked ammonia in the furnace feed stream 20.

[0063] The partially cracked ammonia in the furnace feed stream 20 can be heated by heat exchange in the heat exchanger E305 before being fed as the preheated furnace feed stream 22 at the preselected furnace feed temperature and the preselected furnace feed pressure. The heating medium used in the heat exchanger E305 can be any suitable fluid (e.g., hydrogen and / or nitrogen product gas output from the furnace F201 or other suitable heat transfer fluid). The preselected furnace feed pressure can be a suitable feed pressure (e.g., a pressure of 3.8 MPa, a pressure between 3 MPa and 4.1 MPa, etc.). The preselected furnace feed temperature can also be a suitable feed temperature (e.g., a temperature between 300°C and 500°C, 450°C, 500°C, etc.). In some embodiments, the inlet feed temperature of the preheated furnace feed stream 22 can be limited to a preselected furnace feed temperature (e.g., a temperature of 500°C, a temperature between 400°C and 500°C, etc.) to help limit the inner wall temperature of one or more ammonia cracking tubes through which the preheated furnace feed stream 22 can enter so that the ammonia in the stream can be cracked within the furnace F201.

[0064] In some embodiments, heat exchanger E305 may also have a preselected temperature rating. For example, in some embodiments, heat exchanger E305 may have a temperature rating between 500°C and 700°C. The selected temperature rating for heat exchanger E305 may be specified to take into account the preheating conditions that the particular heat exchanger may be expected to experience during ammonia cracking operations, and the availability of equipment that can meet these conditions. Other embodiments may utilize other heat exchangers with other temperature profiles and other suitable temperature ratings.

[0065] The furnace F201 may include a combustion chamber and one or more catalyst-filled tubes that may be positioned in the radiant section 89 of the furnace F201, which may be considered a furnace reactor or a primary ammonia cracking reactor. The preheated furnace feed stream 22 may pass through the one or more catalyst-filled tubes within the radiant section 89 of the furnace F201 to undergo ammonia cracking therein. At least one fuel may be combusted in the combustion chamber to produce flue gas by combustion of the fuel for heating the preheated furnace feed stream 22 comprising ammonia as well as hydrogen and nitrogen (e.g., by pre-cracking of ammonia that may be provided by one or more pre-reactors) to facilitate cracking of the ammonia passing through the one or more catalyst-filled tubes of the furnace F201.

[0066] Catalyst material within furnace F201 (e.g., catalyst material within one or more catalyst-filled tubes, which may be, for example, tubes filled with catalyst material or lined with catalyst material) may be positioned to help increase the amount of ammonia cracking by reducing the load required to heat a portion of the cracked stream to the reaction temperature for ammonia cracking, which may be carried out within the furnace's combustion chamber using heat from the furnace's burner.

[0067] As described above, the furnace F201 may include a combustion chamber that burns at least one fuel to produce flue gas and heat to promote ammonia cracking within the furnace F201. In some configurations, a stream 62 of air or other oxidant (e.g., oxygen-enriched air, etc.) may be preheated by heat exchange in the oxidant preheating heat exchanger E2141 to produce a stream 64 of preheated oxidant before passing through a forced draft fan K212. The preheated oxidant of stream 64 may be mixed with a fuel stream 70 (e.g., natural gas, hydrogen, a mixture of natural gas and hydrogen, etc.) fed to a burner (not shown) of the furnace F201 to cause the fuel to burn in the furnace's combustion chamber. The preheated oxidant can help reduce the fuel required to promote combustion to produce the heat level required for ammonia cracking.

[0068] One or more tubes in the radiation section 89 of the furnace F201 may be filled with at least two types of ammonia cracking catalysts in multiple different layers, including an upstream layer positioned at and / or near the inlet of the furnace F201 and a downstream layer positioned at and / or near the outlet of the furnace, through which the cracked ammonia product may be output. In some contemplated embodiments, one or more tubes may also include at least one intermediate layer of catalyst material between the upstream layer of catalyst material and the downstream layer of catalyst material. In other embodiments, there may be only an upstream layer and a downstream layer of catalyst material.

[0069] The upstream and downstream catalyst materials in one or more tubes in the radiant section 89 of the furnace F201 may have different activation temperature requirements. For example, the upstream layer may have a lower activation temperature requirement than the downstream layer of catalyst material. In some embodiments, the activity of the catalyst material of the upstream layer may also be lower than that of the downstream layer (for example, the upstream layer may be a less active portion of the catalyst material of the furnace F201). In other embodiments, the catalyst material of the upstream layer may be more active than that of the downstream layer (for example, the upstream layer may be a more active portion of the catalyst material of the furnace F201 that is more active than a less active portion of the catalyst material of the furnace F201).

[0070] For example, a ruthenium-based catalyst may be used in a first upstream layer of catalyst material within each tube of furnace F201 such that a faster reaction rate may allow the metal temperature to be maintained within preselected design limits (e.g., a design limit of approximately 660° C., a design limit between 600° C. and 700° C., etc.). A second downstream layer of catalyst material in one or more tubes of furnace F201, downstream of the first layer of catalyst material, may include a lower cost but lower activity nickel-based catalyst or an iron-based catalyst (e.g., an example of a lower activity portion of the catalyst material of furnace F201 that is less active than a higher activity portion of the catalyst material of the furnace may be a Ru-based catalyst in the first upstream layer, etc.).

[0071] In other embodiments, the first upstream layer and the second downstream layer of catalyst material within one or more tubes of furnace F201 may use other types of catalyst materials. In some configurations, the upstream layer of catalyst material may have a lower activation temperature than the downstream layer of catalyst material, and in other configurations, the upstream layer of catalyst material may have a higher activation temperature than the downstream layer. In other embodiments, one or more tubes of furnace F201 may have a single type of catalyst material therein.

[0072] The furnace F201 can be operated by burning fuel for heating ammonia of the preheated furnace feed stream 22 fed into one or more tubes for cracking ammonia to produce hydrogen and nitrogen. The furnace F201 can output at least one cracked gas stream 24, which can leave the radiation section 89 of the furnace F201 at a preselected outlet temperature (e.g., a temperature of 640°C, a temperature between 600°C and 700°C, a temperature between 620°C and 750°C, etc.). The cracked gas output from the furnace F201 can be fed to the heat exchanger E305 as a heating medium for preheating the furnace feed stream 20 output from the second pre-reactor C142. The cooled cracked gas can be output from the heat exchanger E305 at a preselected cooling temperature. Such a temperature can be lower than the temperature at which the gas is output from the furnace F201 (e.g., between 500°C and 600°C, between 450°C and 550°C, etc.). The cooled cracked gas may be output from heat exchanger E305 for being fed to other heat exchangers for additional cooling before the cracked gas is fed to hydrogen recovery unit U501.

[0073] For example, a cooling stream 26 of cracked gas can be output from heat exchanger E305 to be fed to heat exchanger E310 and then to other heat exchangers E311 and E312 to be used as a heating medium to heat ammonia passing therethrough so that the cracked gas can be cooled toward a desired hydrogen recovery unit feed temperature.

[0074] For example, the cooled cracked gas of stream 26 can be fed to heat exchanger E310 to provide heating to superheat the ammonia, thereby further reducing the temperature of the cracked gas to cool it. Cracked gas stream 28 can be output from heat exchanger E310 to be fed from heat exchanger E310 to heat exchanger E311 to provide a charge of further heated liquid ammonia fed thereto via stream 8 to even further reduce the temperature of the cracked gas. Cracked gas stream 30 can be output from heat exchanger E311 to be fed to heat exchanger E312 to provide a charge of further heated pressurized liquid ammonia of stream 6 to again further reduce the temperature of the cracked gas.

[0075] Each of the heat exchangers E305, E310, E311 and E312 is Figure 1 The exemplary embodiment of the invention is depicted as separate shell and tube heat exchangers, with ammonia passing through the tubes and cracked gas passing through the shell side. However, this arrangement can be reversed. Alternatively, the heat exchangers can be combined into a single shell and tube heat exchanger, or indeed different types of heat exchangers can be used.

[0076] The cracked gas stream 32 can be output from the heat exchanger E312 to be fed to the hydrogen recovery unit U501 at a preselected hydrogen recovery unit feed temperature. For example, the heat exchanger E312 can output the cooled cracked gas to the heat exchanger E323, which can utilize a refrigerant or coolant (e.g., cooling water, etc.) to facilitate further cooling of the cracked gas, as may be desired, to further cool the cracked gas to a preselected hydrogen recovery unit feed temperature. Then, the fully cooled cracked gas can be output from the heat exchanger E323 to be fed to the hydrogen recovery unit U501 as a hydrogen recovery feed stream 34.

[0077] In some embodiments, the hydrogen recovery unit U501 can be configured as a pressure swing adsorption (PSA) system. In other embodiments, another type of adsorption system (e.g., vacuum pressure swing adsorption, temperature swing adsorption, etc.) can be used. In other embodiments, another type of hydrogen separation system can be utilized to separate the hydrogen of the cracked gas from nitrogen and other components of the cracked gas.

[0078] The hydrogen recovery unit U501 can separate hydrogen from other components of the cracked gas to provide a hydrogen product stream 40 that can contain hydrogen at a desired purity concentration (eg, 99 mol % hydrogen, between 99 mol % and 100 mol % hydrogen, etc.).

[0079] The hydrogen recovery unit U501 may also output stream 42, which may be an exhaust gas containing nitrogen, residual hydrogen, and residual ammonia. In some embodiments, stream 42 may also include other minor components.

[0080] The hydrogen in stream 40 may be fed to a hydrogen liquefaction unit (not shown) to produce liquid hydrogen. In other embodiments, the hydrogen in stream 40 may be fed to at least one downstream plant process to use the hydrogen.

[0081] The exhaust gas of stream 42 may be fed to the combustion chamber of furnace F201 as fuel stream 60 for combustion therein. Alternatively (or additionally), stream 42 may be divided into a plurality of portions, one of which may be used as a fuel stream. In other embodiments, stream 42 may be divided, and the divided portions may not be fed to furnace F201 as fuel stream 60 (e.g., combustion of furnace F201 may be provided solely by fuel from fuel stream 70).

[0082] For example, stream 42 may be split so that a first portion 44 of the exhaust gas in stream 42 is heated by heat exchange in heat exchanger E2112 to produce a heated exhaust gas stream 60, which is then fed to one or more burners in furnace F201 along with an air feed 64 and an optional fuel stream 70 (e.g., a natural gas feed stream, etc.). A minimum amount of natural gas or other suitable fuel for fuel stream 70 may be used as a trim fuel to provide the required fuel balance in the combustion section of the combustion chamber to supplement the ammonia and / or hydrogen present in the first portion 44 of the exhaust gas fed to furnace F201.

[0083] The second portion 46 of the exhaust gas 42 (when used) can be sent to a compression system K681 (e.g., a multi-stage compressor, a compressor assembly, etc.) for compression. The compression system K681 can have multiple stages, with intercoolers between each stage, and an aftercooler after the last stage. Heat can be recovered from the compressed gas in the intercooler and aftercooler by heat exchange with a heat transfer fluid. Heat can also be recovered from the lubricating oil and, in the case of a positive displacement compression unit, from the cylinders of the compression unit by a heat transfer fluid.

[0084] Intercoolers and aftercoolers that can be used are Figure 1 A single heat exchanger E6816 in the embodiment of the present invention is shown which can recover heat from the stream 48 of compressed exhaust gas by heat exchange with the stream 52 of heat transfer fluid to produce a stream 50 of cooled compressed exhaust gas and a stream 54 of heated heat transfer fluid, which can be used in another process or heat exchanger (e.g., heat exchanger E271, etc.). For example, the heat transfer fluid heated in cooler E323 and in intercooler and aftercooler E6816, etc., can be used to provide a duty of preheating liquid ammonia by heat exchange in heat exchanger E271.

[0085] The cooled compressed waste gas in stream 50 can be fed to phase separator C6816, where condensate can be removed as stream 56. Then, the compressed waste gas can be recycled to hydrogen recovery unit U501 as stream 58 to recover additional hydrogen. In other embodiments, the method can be operated without compression system K681 and using the second part 46 of the waste gas to be treated to be recycled back to the hydrogen recovery unit U501. Such an embodiment may result in a lower hydrogen recovery rate in the hydrogen recovery unit U501. Although reducing the hydrogen recovery rate may result in less hydrogen product, the reduced hydrogen recovery rate is still desirable, because more hydrogen is present in the waste gas, and the carbon intensity (CI) for the method can be reduced, thereby reducing the demand for natural gas as an adjustment fuel and reducing carbon dioxide emissions. In addition, since compression system K681 is not used, this type of arrangement can provide less total power consumption.

[0086] The furnace F201 may discharge at least one flue gas stream 72. The discharged flue gas may be at a preselected flue gas discharge temperature (e.g., a temperature between 650°C and 700°C, a temperature of about 686°C, etc.). The flue gas stream 72 may pass from the radiant section 89 of the furnace F201 to the convection section 90 of the furnace F201, where it may be used as a heating medium as described above. For example, the flue gas output from the furnace F201 may provide a duty for heating the intermediate gas from stream 16 in the heat exchanger E2103, thereby reducing the temperature of the flue gas, and then the flue gas may be output from the heat exchanger E2103 as a heating medium stream 74 for being fed to the heat exchanger E2012 to provide a duty for further heating the heated ammonia gas from stream 12 in the heat exchanger E2102, thereby further reducing the temperature of the flue gas. The flue gas may be directed to provide a heating duty in a direction countercurrent to the flow of feed gas to the radiant section of the furnace F201.

[0087] The cooled flue gas can be output from heat exchanger E2102 as further cooled flue gas stream 76 for being fed to heat exchanger E2142 to provide a duty of heating air from stream 62 in heat exchanger E2142, thereby further reducing the temperature of the flue gas. The further cooled flue gas can be output from heat exchanger E2142 as stream 78 to be fed to heat exchanger E2112 to provide a duty of preheating the first portion 44 of the exhaust gas stream 42 in heat exchanger E2112, thereby further cooling the flue gas.

[0088] The cooled flue gas may be output as stream 80 from the convection section 90 of the direct fired tube furnace F201 at a preselected flue gas output temperature (e.g., a temperature in excess of 100° C., a temperature of about 121° C., a temperature above the condensation point of water, a temperature at or above a preselected acid dew point to avoid acid condensation, etc.). In some embodiments, the cooled flue gas may be discharged as an exhaust stream 82 via an induced draft fan K211. Embodiments may be configured to utilize as much practical energy as possible from the flue gas to economically discharge the cooled flue gas into the atmosphere. In some embodiments, the flue gas may first undergo other treatments (e.g., carbon dioxide capture, particulate removal treatment, etc.) depending on its composition.

[0089] In some embodiments, oil may be present in liquid ammonia in an amount of up to about 5 ppm from a boil-off gas compressor (not shown) used with an ammonia storage tank (not shown), at the location where the ammonia is produced, or at the site where the ammonia is cracked, or indeed anywhere in transit between the two sites. In some configurations, it may be desirable to remove the oil before the ammonia is exposed to the catalyst in the pre-reactor and / or furnace F201. The oil may be removed by passing the ammonia through an activated carbon bed or via one or more other types of oil removal treatment units. If oil is to be removed from the ammonia, an oil removal unit (not shown) can be located in stream 2 (e.g., in the feed line to pump P101), in stream 4 (e.g., between pump P101 and heat exchanger E271), in stream 6 (e.g., between heat exchanger E271 and heat exchanger E312), in stream 8 (e.g., between heat exchangers E312 and E311), in stream 10 (e.g., between heat exchangers E311 and E310), or at other suitable locations upstream of the pre-reactor and furnace F201.

[0090] One or more tubes of furnace F201 and / or a pre-reactor upstream of furnace F201 may include catalyst materials to promote ammonia cracking. For example, these catalyst materials may include metals for promoting ammonia cracking reactions to crack ammonia into nitrogen and hydrogen. The metals that may be included in the catalyst materials may include transition metals, such as those in Group 6 of the Periodic Table (e.g., chromium (Cr) and molybdenum (Mo)); those in Group 8 of the Periodic Table (e.g., iron (Fe), ruthenium (Ru) and osmium (Os)), those in Group 9 of the Periodic Table (e.g., cobalt (Co), rhodium (Rh) and iridium (Ir)), those in Group 10 of the Periodic Table (e.g., nickel (Ni), palladium (Pd) and platinum (Pt)) and those in Group 11 of the Periodic Table (e.g., copper (Cu), silver (Ag) and gold (Au)). Metalloids (e.g., tellurium (Te), etc.) may also be used.

[0091] The activity of some of these metals as ammonia cracking catalysts is reported by Masel et al. (Catalyst Letters, Vol. 96, No. 3-4, July 2004) to vary in the following order:

[0092] Ru>Ni>Rh>Co>Ir>Fe>>Pt>Cr>Pd>Cu>>Te

[0093] (Ru is the more active catalyst and Te is the less active catalyst).

[0094] The metal of the catalyst may be unsupported, but is typically supported on a suitable support (e.g., a metal oxide support, such as silica (SiO2), alumina (Al2O3), zirconium oxide (ZrO2), or a mixed metal oxide support, such as spinel (MgAl2O4) or perovskite (CaTiO3)). The activity of a supported metal catalyst may depend in part on the loading of the catalytically active metal on the support. In this regard, the loading of the metal may vary according to a preselected set of design criteria. In some embodiments, the metal loading of the catalyst material may be in the range of about 0.1 wt % to about 70 wt %. For example, in some catalyst materials, the loading may be toward the lower end of the range (e.g., for a more active metal, such as ruthenium, about 0.1 wt % to about 10 wt % or about 0.2 wt % to about 5 wt %), while for a less active metal (e.g., nickel), the loading may be toward the upper end of the range (e.g., about 20 wt % to about 65 wt %, etc.).

[0095] The supported metal catalysts that may be used may be unpromoted or may be promoted with at least one other metal, such as one or more Group 1 metals (e.g., lithium (Li), sodium (Na), and potassium (K)); Group 2 metals (e.g., magnesium (Mg) and calcium (Ca)) or Group 13 metals (e.g., aluminum (Al)), to improve the activity of the catalyst material.

[0096] Bimetallic catalysts or catalysts containing two catalytically active metals are also suitable for the present invention. Examples include composite metals or metal alloys or metal nanoclusters supported on perovskites, composite oxides or nitrides, or mixed oxides or mixed nitrides disclosed in U.S. Patent Application Publication No. 2021 / 0001311A (e.g., CoNi-MgSrCeO4 and 1 wt. % K-CoNi-MgSrCeO4). Other types of multimetallic ammonia cracking catalysts may also be used.

[0097] In embodiments of the apparatus and methods, any number of suitable ammonia cracking catalysts may be used as catalyst materials. Examples of suitable catalyst materials are disclosed in U.S. Patent Application Publication No. 2015 / 0217278A and Lamb et al. (Int. J. Hydrogen Energy, 44 (2019) pp. 3726-3736) and Boisen et al. (J. Catalysis 230 (2005) pp. 309-312).

[0098] Prior to operation of the apparatus 1 for ammonia cracking, the catalyst material within one or more tubes and / or one or more pre-reactors (e.g., the first and second pre-reactors C142 and C141 in embodiments where multiple pre-reactors may be used) of the furnace F201 may be fully activated by a catalyst activation method. The catalyst material may be considered fully activated when the catalyst material has been sufficiently activated so that ammonia cracking may occur effectively in accordance with the preselected ammonia cracking design temperature of the apparatus 1 for ammonia cracking. For example, when the entire oxide layer or passivation layer is removed from the catalyst material, the catalyst material may be fully activated. As another example, when a majority of the oxide layer or passivation layer is removed from the catalyst material (e.g., removing 55% to 100% of the passivation layer and / or oxide of the catalyst material, removing 75% to 100% of the passivation layer and / or oxide of the catalyst material, etc.), the catalyst material may be fully activated so that the ammonia cracking temperature required for the ammonia cracking temperature may be significantly reduced within the preselected design parameters of the apparatus 1 for ammonia cracking. As yet another example, when the use of a catalyst for promoting ammonia cracking may be provided without providing any exothermic heat through the catalyst material, full activation of the catalyst material may occur. As yet another example, when the use of the catalyst material for promoting ammonia cracking can be provided without using excessively high ammonia cracking reaction temperatures within the preselected temperature design limits of the apparatus 1, full activation of the catalyst material can be obtained. As yet another example, when the catalyst material is sufficiently activated to allow the apparatus 1 for ammonia cracking to crack ammonia within its preselected design criteria, full activation of the catalyst material can be detected. As yet another example, when the use of the catalyst for promoting ammonia cracking can be provided without a significant level of exotherm from the catalyst, the catalyst material can be fully activated. The fully activated catalyst material can be positioned so that the catalyst material is in a suitable state (e.g., by substantially removing the passivation layer and / or significantly removing oxides from the catalyst material, etc.) to promote ammonia cracking within an acceptable rate, which can be defined by the preselected design criteria of the apparatus 1 for ammonia cracking. Detection of full activation of the catalyst material can be provided by monitoring a preselected set of criteria, which can include a predetermined temperature profile and / or a predetermined reactant concentration profile during the catalyst activation process.

[0099] The catalyst activation method may be used at the beginning of the process (e.g. after installation of the ammonia cracking facility, after a turnover in which spent catalyst material is replaced with fresh catalyst material, etc.). The activation method for catalyst material activation may utilize process elements of the ammonia cracking plant 1 before the ammonia cracking plant 1 is fed with a larger ammonia feed to produce hydrogen through an ammonia cracking operation.

[0100] For example, in the first catalyst activation stage, hydrogen (H2) can be fed as a first reactant into the apparatus for feeding into the pre-reactor and furnace F201 to help promote activation of the catalyst material within the tubes in the radiant section 89 of furnace F201 and the pre-reactors (e.g., pre-reactors C141 and C142). In some configurations, hydrogen H2 can be fed into a conduit through which ammonia will pass during the ammonia cracking operation to be preheated before being fed into the pre-reactor and furnace F201. For example, hydrogen H2 can be fed into a preheating heat exchanger feed conduit through which a stream 6 of preheated liquid ammonia will pass to the heat exchanger E312 when the ammonia cracking operation occurs.

[0101] In some embodiments, hydrogen H2 can be fed as a mixture of hydrogen and nitrogen to provide a desired concentration of hydrogen as the first reactant gas during the first catalyst activation stage. Nitrogen can also be injected into the reactant gas when the reactant gas is passed to the pre-reactor and furnace F201 via at least one nitrogen injection feed (N2). The hydrogen reactant stream can be preheated by a heat exchanger via the flue gas output from the combustion of a fuel stream 70, the combustion of which can occur via the combustion chamber of furnace F201. The heat from the burning fuel can provide preheating for the first reactant, and also provide a heat source for heating the catalyst material during catalyst activation, so that the temperature of the catalyst increases in a desired sequential manner, while the catalyst is also exposed to the reactant hydrogen for catalyst material activation.

[0102] For example, flue gas output from furnace F201 can be used as a heating medium for preheating hydrogen reactant gas passing through one or more preheating heat exchangers (e.g., heat exchanger E2102 or other heat exchangers). In some embodiments, the hydrogen reactant gas can be injected so that it enters only a subset of such heat exchangers, depending on how much preheating of the hydrogen reactant may be required to provide the desired heating of the catalyst material via the heated flow of reactant gas.

[0103] The preheated hydrogen reactant gas may then be fed to the first pre-reactor C141 to pass through the catalyst material bed in the vessel of the reactor. The hydrogen reactant gas and the products from the catalyst activation reaction that may occur from the oxide, oxide layer or passivation layer of the catalyst material that reacts with the hydrogen of the reactant gas stream may be output from the first pre-reactor C141 and heated in a heat exchanger E2103 to heat the reactant stream to the desired second pre-reactor feed temperature for subsequently feeding the reactant stream to the second pre-reactor C142.

[0104] Subsequently, the preheated hydrogen reactant gas can be fed through a bed of catalyst material in a second prereactor C142 so that the hydrogen reactant gas and products from a catalyst activation reaction that may occur from an oxide of the catalyst material that may react with the hydrogen in the reactant gas flow from a passivation layer can then be output from the second prereactor C142 for heating in a heat exchanger E305 to heat the reactant flow to a desired furnace feed temperature for subsequently feeding the reactant flow to one or more tubes of furnace F201 for activation of the catalyst material within the tubes of the radiant section 89 of furnace F201.

[0105] The first reactant gas and catalyst activation product elements formed through the catalyst activation process can be carried out in the first stage of catalyst activation, wherein the first reactant gas (e.g., hydrogen) reacts with the oxide of the catalyst material that has not yet been fully activated (e.g., the oxide of the oxide layer, the oxide of the passivation layer, etc.), so that the reactant gas is recycled during the first stage of catalyst activation. For example, the reactant gas and the catalyst activation product elements therein can be output from the tube of the radiation section 89 of the furnace F201, while also being heated by the combustion of the fuel in the furnace, so as to then pass through the heat exchangers E305, E310, E311 and / or E312, for preheating the fresh and / or recycled reactant gas fed to the pre-reactor and the furnace F201. Then, the first reactant gas can pass through the gas-liquid separation tank positioned upstream of the hydrogen recovery unit U501 to help remove water that may exist through the activation process from the reactant gas, and can then be arranged through the reactant recirculation conduit to be recycled back through the heat exchanger, pre-reactor and tube of the furnace F201. Reactant recirculation conduit arrangement can be arranged and configured to make the reactant of recycling pass through the first recirculation conduit section HR1, and this first recirculation conduit section is positioned between the upstream position of hydrogen recovery unit U501, so that the first reactant gas passes to compression system K681, is used for compressing therein, with output for recirculation subsequently, helps to consider the pressure drop that may occur because reactant gas passes through different process elements.Nitrogen (N2) can also be fed into the first reactant to increase the nitrogen concentration of reactant gas and / or help to provide the desired flow rate for reactant gas.For example, nitrogen can be mixed with the hydrogen of the first reactant, to provide the first reactant under the preselected flow rate and / or provide the hydrogen of preselected concentration in the first reactant for the first stage of catalyst activation.

[0106] When it may be necessary during the recirculation of the reactant gas, some of the reactant gas can be discharged via the exhaust stream (exhaust) to take into account the desired hydrogen concentration or desired temperature profile within the reactant gas and / or to remove unwanted components (e.g., to reduce the water content within the reactant gas, etc.). The exhaust can allow water that may collect in the reactant gas to be removed via the exhaust. In addition, fresh hydrogen H2 and / or nitrogen (N2) can also be injected into the recycled reactant gas during the first catalyst activation stage to provide a supplement of hydrogen and / or nitrogen to take into account the exhaust and / or reaction of hydrogen with oxides, oxide layers and / or passivation layers of catalyst materials in the furnace F201 and pre-reactors (e.g., pre-reactors C141 and C142) that may occur, and these materials have not yet been fully activated.

[0107] After the pressure of the reactant gas is increased by the compression of the compression system K681, the output reactant gas that is recycled can have a higher pressure and can pass through the phase separator C6816. Moisture (e.g., water) can be removed as a liquid stream 56 via the phase separator, and the reactant gas can be subsequently output as a stream 58 for being fed to the second reactant recirculation conduit section HR2, which has an inlet positioned between the phase separator C6816 and the hydrogen recovery unit and an outlet that is connected to the conduit fluid, and the reactant gas can be guided to the heat exchanger, the pre-reactor, and the furnace F201 by the conduit. For example, the outlet of the second reactant recirculation conduit section HR2 can be fed at a position where nitrogen (N2) can be injected into the upstream of one or more heat exchangers (e.g., the upstream of heat exchangers E312, E311, and / or E310), or fed at another position upstream of the pre-reactor and the upstream of the furnace F201, to pass through one or more of the tubes of the heat exchanger, the pre-reactor, and the furnace F201.

[0108] After the first level of catalyst activation is detected, the catalyst activation method can be adjusted to transition to and then begin the second stage of catalyst activation to complete the catalyst activation process. In some embodiments, the first level of catalyst activation can be preselected or predefined so that the catalyst material of the pre-reactor is fully activated during the first level of catalyst activation. In addition, the first level of catalyst activation can be preselected or predefined so that the catalyst material of the higher activity catalyst material in the tube of the furnace F201 can be fully activated (for example, in embodiments where the upstream layer includes a higher activity catalyst material (e.g., a Ru-based catalyst material) and the downstream layer includes a lower activity catalyst material (e.g., a Ni-based catalyst material), etc., the upstream layer of the catalyst material of the tube of the furnace F201). The first level of catalyst activation can be predefined or preselected so that at least one layer of catalyst material of the furnace F201 has not yet been fully activated and requires additional activation to be fully activated.

[0109] In some embodiments, one or more sensors may collect data (e.g., temperature data, hydrogen concentration data, etc.) to detect that a first level of catalyst activation has occurred to indicate that the first stage of catalyst activation has been reached and that a transition to a second stage of catalyst activation is appropriate. For example, detection of a first preselected temperature profile and / or hydrogen concentration present in furnace F201, which may be provided by one or more sensors of furnace F201 or apparatus 1, may be used to determine that a first level of catalyst activation has occurred. For example, such detection may be facilitated by a controller or control device communicatively coupled to one or more such sensors that receives sensor data and provides an output to a user to indicate that a preselected first level of catalyst activation has occurred.

[0110] Examples of a detected first level of catalyst activation may include a temperature between 150° C. and 500° C. detected at an outlet region or outlet of the radiant section 89 of the furnace F201, a duration of exposure to the hydrogen first reactant between 1 hour and 48 hours, and / or a hydrogen concentration equal to or greater than 10 mol% (e.g., between 10 mol% and 30 mol%, between 10 mol% and 20 mol%, between 10 mol% and 25 mol%, etc.) detected at the outlet of the tubes of the furnace having the upstream and downstream layers of catalyst material. The first level of catalyst activation may also (or alternatively) be detected based on exothermic monitoring within the design constraints of the apparatus 1. The one or more exothermic conditions that may be monitored may include, for example, detecting a temperature increase within a preselected time period during the first catalyst activation stage that is greater than a preselected temperature increase (e.g., a 5°C-50°C temperature increase within a preselected time period during the first catalyst activation stage, a 15°C temperature increase within a preselected time period during the first catalyst activation stage, a 5°C-15°C temperature increase within a preselected time period during the first catalyst activation stage, a 3°C-12°C temperature increase within a preselected time period during the first catalyst activation stage, etc.)

[0111] Other embodiments may utilize other predetermined criteria to facilitate detection of the first level of catalyst activation for triggering a transition from the first stage of catalyst activation to the second stage of catalyst activation, which may occur immediately after completion of the first stage, such that adjustment from the first stage of catalyst activation to the second stage of catalyst activation occurs directly after the transition from the first stage of catalyst activation to the second stage of catalyst activation.

[0112] For example, in response to the detection of this first level of catalyst activation, a second stage of catalyst activation may be initiated to continue the catalyst activation method. For example, such a catalyst activation stage transition may occur after the temperature of the tubes in the radiant section 89 of the furnace F201 is at a temperature in the range of 300°C-550°C and / or the hydrogen concentration is detected as being at a concentration in the range of, for example, 20mol%-25mol% or 15mol%-25mol%. As another example, detection of the temperature of the flue gas output from the radiant section 89 of the furnace F201 at 400°C, 450°C, 500°C, or other temperatures in the range between 400°C-500°C may be used to detect the first level of catalyst activation and trigger a transition to the second stage of catalyst activation. As another example, detection of the temperature of reactant gases (having reactant / catalyst material reaction products that may include water, etc.) output from the tubes of the radiant section 89 of furnace F201 at 400°C, 450°C, 500°C, or other temperatures within the range of 400°C-500°C can be used to detect a first level of catalyst activation and trigger a transition to a second stage of catalyst activation.

[0113] As yet another example of detection for satisfying a first level of catalyst activation, a preselected temperature threshold for a particular location (e.g., an exit area of ​​a radiant section 89 of a furnace, etc.) may be selected based on a temperature rating of a heat exchanger upstream of the furnace F201 for preheating ammonia feed to be fed to the tubes of the furnace F201 for ammonia cracking operation and / or an SCR that may be utilized upstream of the furnace F201 for preheating ammonia feed to be fed to the tubes of the furnace F201 for ammonia cracking. For example, a temperature selected to facilitate detection of satisfying a first level of catalyst activation for transitioning from a first stage of catalyst activation to a second stage of catalyst activation may be selected to avoid the temperature of the equipment being at its temperature rating, exceeding its temperature rating, or within a preselected variance of its temperature rating (e.g., 15°C or 20°C below its temperature rating). Such a temperature selection profile may be used to help avoid equipment being at or exceeding its design temperature rating during a catalyst activation process, and the catalyst activation method may be used to fully activate all catalyst materials of the tubes of the furnace F201 and the pre-reactor upstream of the furnace.

[0114] Of course (and as described above and elsewhere herein), other first preselected catalyst activation temperature profiles and / or first preselected catalyst activation hydrogen concentrations may also be used to predefine the first level of catalyst activation obtained via the first stage of catalyst activation. For example, the choice of temperature profiles, reactant concentrations, and / or other parameters (e.g., exotherm-related parameters) that may be utilized may depend on the size of the tubes of the furnace F201 with catalyst material, the size and number of pre-reactors with catalyst material, the type of catalyst material being activated, and the temperature ratings of the different equipment of the apparatus 1.

[0115] The second stage of catalyst activation can be started by stopping the feeding of hydrogen (or other first reactant gas) into the pre-reactor and furnace F201 and starting to feed ammonia as the second reactant into the pre-reactor and furnace catalyst material. For example, the feed of liquid ammonia 2 can be passed through the preheating heat exchanger, the pre-reactor and the furnace via pump P101, and the pump is started to feed ammonia as the second reactant. In some embodiments, nitrogen can be mixed with ammonia to dilute the ammonia concentration in the ammonia feed passed into the pre-reactor and furnace F201 as the second reactant. For example, when the second reactant passes through the tube of the pre-reactor and the furnace F201 containing the catalyst material, nitrogen can be mixed with ammonia to provide the required flow rate of the second reactant. For example, nitrogen can be mixed with the ammonia of the second reactant to provide the second reactant at a preselected flow rate and / or provide a preselected concentration of ammonia in the second reactant used for the second stage of catalyst activation.

[0116] In addition, further feeding of hydrogen H2 as the first reactant can be stopped, and the hydrogen reactant having the catalyst activation reaction product included therein can be stopped by discharging the hydrogen reactant having the catalyst activation reaction product therein via at least one discharge conduit for providing at least one discharge stream (discharge) to be fed and / or being recycled via the reactant recirculation conduit arrangement. The discharge of the used and / or recycled hydrogen reactant stream can be discharged so that the reactant gas stream used during the initial first catalyst activation stage is not directly mixed with the ammonia fed into the device via the feed of the liquid ammonia 2 as the second stage for catalyst activation. However, the discharge of the hydrogen reactant gas can be carried out so that hydrogen passes through heat exchangers E305, E310, E311 and E312 to preheat ammonia. Flue gas from furnace F201 can also be used to preheat ammonia by heat exchangers E2103 and E2012 and oxidant preheating heat exchanger E2142 to control the temperature of the ammonia reactant gas also used during the second stage of catalyst activation.

[0117] The feed rate of ammonia provided as a feed of liquid ammonia as a second reactant for the second stage of catalyst activation may be a feed rate significantly lower than the feed of liquid ammonia 2 provided during the ammonia cracking operation. For example, the feed rate of ammonia for the second stage of catalyst activation may be between 5% and 45% or between 20% and 40% of the typical design feed rate of liquid ammonia feed for the ammonia cracking operation of apparatus 1. After the hydrogen reactant gas has been sufficiently exhausted, the ammonia used as a reactant for the second stage of catalyst activation may be exhausted via an exhaust conduit (exhaust) upstream of the hydrogen recovery unit, so that the ammonia used in the second stage of catalyst activation is not recycled (for example, it is used in a single-pass process, so the ammonia passes through the pre-reactor and furnace F201 a single time and is not recycled).

[0118] In other embodiments, it is contemplated that ammonia may also be recycled alternatively to further limit the amount of ammonia feed required for the second stage of catalyst activation. In such embodiments, it is contemplated that recycling of ammonia may also utilize a reactant recycle conduit arrangement to provide recycling of ammonia, similar to how the first reactant gas including hydrogen may be recycled.

[0119] As can be understood from the above, the feed of liquid ammonia 2 fed to the second stage of the equipment for catalyst activation can be preheated to the desired temperature by preheating heat exchangers E312, E311, E310 and E2102, and then fed to the first pre-reactor C141. Fresh ammonia from a liquid ammonia source (e.g., a storage container or storage unit for liquid ammonia) can be provided for continued operation of the second stage of catalyst activation, so that the cooler liquid ammonia can provide a heat sink, which can help keep various upstream preheating heat exchangers (e.g., heat exchangers E310, E311, E312, etc.) below a preselected temperature (e.g., to avoid overheating of the heat exchanger exceeding the design temperature specification).

[0120] The preheated ammonia reactant can be preheated so that the ammonia evaporates and is gaseous before being fed to the first pre-reactor C141 via a preheating heat exchanger. The ammonia reactant gas can then be fed to the first pre-reactor C141 to pass through the catalyst material bed in the container of the reactor. Ammonia can react with the catalyst material therein and be partially cracked therein due to the complete activation of the catalyst material (for example, ammonia can be converted into some hydrogen and nitrogen and other components by reacting with the catalyst material in the first pre-reactor). The ammonia reactant gas and the products from the catalyst reaction that may occur can be output from the first pre-reactor C141 and heated in the heat exchanger E2103 to heat the ammonia reactant stream to the desired second pre-reactor feed temperature for subsequently feeding the reactant stream to the second pre-reactor C142.

[0121] The preheated ammonia reactant gas can then be fed through a bed of catalyst material in the second prereactor C142 so that the ammonia reactant gas, as well as products from reactions that may result from the interaction of ammonia with the catalyst material in the second prereactor C142 (e.g., hydrogen and nitrogen), can be output from the second prereactor C142 and fed to a heat exchanger E305 to heat the ammonia reactant flow to a desired furnace feed temperature for subsequently feeding the reactant flow to one or more tubes of the furnace F201 for activation of the catalyst material within one or more tubes of the radiant section 89 of the furnace F201.

[0122] A second reactant gas and catalyst activation product elements (e.g., nitrogen and hydrogen) formed via a catalyst activation method in which a reactant gas (e.g., ammonia) interacts with a catalyst material can be performed in a second stage of catalyst activation such that the reactant gas passes through the tubes of furnace F201. Ammonia and reaction products (e.g., nitrogen and hydrogen) can pass through the furnace tubes to help fully activate a layer of less active catalyst material (e.g., a downstream layer, wherein the downstream layer is a Ni-based catalyst material and the upstream layer is a Ru-based catalyst material) within the tubes that has not yet been fully activated. The ammonia reactant gas and product elements can then be output from the radiation section 89 of furnace F201, while flue gas can also be output from the radiation section 89 for being fed to the convection section 90 of furnace F201 to pass through different heat exchangers E2103, E2102, E2142, and / or E2112.

[0123] For example, the ammonia reactant gas and the catalyst activation product elements therein can be output from the tubes of the radiant section 89 of the furnace F201, while being heated by the combustion of the fuel in the furnace, and then used to preheat the fresh ammonia reactant gas through the heat exchangers E305, E310, E311 and / or E312. Then, after being output from the heat exchanger E312, the ammonia reactant gas can be discharged upstream of the hydrogen recovery unit U501.

[0124] Alternatively, in embodiments where ammonia may be recycled, the ammonia reactant gas and activation products may be arranged via a reactant recycle conduit to be recycled back through the heat exchangers, prereactors and tubes of furnace F201. In such embodiments where ammonia recycle may be utilized, the reactant recycle conduit arrangement may be arranged so that the recycled second reactant (and the products from the catalyst activation reaction, some of which may be present along with catalyst material therein) passes through compression system K681 via a first reactant recycle conduit segment HR1 which may allow the first reactant to pass from a location upstream of hydrogen recovery unit U501 through a feed conduit of compression system K681 for compression therein and subsequent output for recycle to help account for pressure drops that may occur with the reactant gas passing through different process elements. For example, the reactant gas recirculation conduit HR2 can be arranged to facilitate the directing of compressed reactant gas output from the compression system K681 so as to also be recycled back to the preheating heat exchanger in such an embodiment (for example, compressed ammonia can be recycled so that it passes through the phase separator C6816 and is then redirected back to the heat exchanger and / or prereactor via the second reactant recirculation conduit section HR2 at a location between the hydrogen recovery unit U501 and the phase separator).

[0125] The feed rate of the liquid ammonia feed 2 may be adjusted to also account for the recycle of the ammonia reactant gas (where recycle of ammonia is utilized), and the ammonia reactant gas may be periodically vented via at least one vent stream (vent) during the second stage of catalyst activation to account for one or more parameters of a preselected control criterion where at least some ammonia is recycled rather than vented in a once-through treatment scheme.

[0126] During the second stage of catalyst activation, ammonia can be passed through the tubes of the first pre-reactor C141, the second pre-reactor C142, and the radiant section 89 of the furnace F201 to provide sequential heating of the catalyst materials therein, thereby providing a preselected order of complete catalyst activation. For example, the heating of the catalyst materials can be provided via the passage of heated ammonia gas, which can be heated by the combustion of fuel in the furnace F201, so that the least active catalyst material in the tubes of the furnace is fully activated last. For example, where the downstream layer of catalyst material in the tubes of the furnace F201 is Ni-based and the upstream layer of catalyst material is Ru-based, the downstream Ni-based catalyst material can be fully activated last during the second stage of catalyst activation by using an ammonia reactant gas.

[0127] In some embodiments, heating of the catalyst material can be provided more directly by feeding a heated second reactant comprising ammonia during the second stage of catalyst activation, and feeding a first reactant comprising hydrogen used in the first stage of catalyst activation, so that the higher activity upstream layer of catalyst material in the tube of furnace F201 is fully activated first, the catalyst material layer of the second prereactor C142 which is more active than the lower activity catalyst material layer of the second prereactor is fully activated second, the catalyst material of the first prereactor C141 is fully activated third, the lower activity catalyst material layer of the second prereactor C142 is fully activated fourth, and the lower activity catalyst material downstream layer in the tube of furnace F201 is fully activated last.

[0128] The heating of the catalyst material provided via the first reactant and the second reactant can be driven primarily via the heat of the flue gases of furnace F201, which can heat the fluid in one or more tubes of the furnace in radiant section 89, and can also be used as the heating medium in one or more preheat heat exchangers. In addition, when the output reactant stream passes through heat exchangers E305, E310, E311 and E312, etc., the heating of the reactants passing through the tubes of furnace F201 can be further utilized to provide preheating of the reactants. The combustion of the fuel in furnace F201 can be considered to be the primary source of heating provided via catalyst activation during the first catalyst activation stage and the second catalyst activation stage.

[0129] Such feeding of the first reactant and the second reactant via the first and second catalyst activation stages can be performed so that in the first stage of catalyst activation using the first reactant, the higher activity catalyst material layer in the tubes of the furnace F201 is fully activated first, the higher activity catalyst material layer of the second pre-reactor C142, which is more active than the lower activity catalyst material layer of the second pre-reactor, is fully activated second, the catalyst material of the first pre-reactor C141 is fully activated third, and the lower activity catalyst material layer of the second pre-reactor C142 is fully activated fourth. Then, the lower activity catalyst material layer in the tubes of the furnace F201 can be finally fully activated by the second reactant including ammonia via the second stage of catalyst activation. In embodiments where the lower activity catalyst material layer in the tubes of the furnace is a downstream layer, this will result in the downstream layer of catalyst material in the tubes of the furnace F201 being fully activated last.

[0130] In some embodiments, it is expected that there may be only a single pre-reactor or more than two pre-reactors. In such embodiments, the first and second stages of catalyst activation may occur so that the higher activity catalyst material layer in the tube of furnace F201 is activated first (e.g., the upstream layer when the upstream layer of catalyst material is a Ru-based catalyst and the downstream layer of catalyst material is a Ni-based catalyst). Then, the pre-reactor may activate their catalyst materials in a sequential manner before the downstream layer of catalyst material, which is the lower activity catalyst material layer in the tube of furnace F201, is finally activated. If there is only one pre-reactor, the first and second stages of catalyst activation may occur so that the higher activity catalyst material in the tube of the furnace is activated first, the catalyst material of the single pre-reactor may be activated second, and then the lower activity catalyst material layer of the tube of furnace F201 may be activated last (e.g., when the Ni-based catalyst is the downstream layer in the furnace tube and the Ru-based catalyst is the upstream layer in the furnace tube, the downstream layer in the tube of furnace F201 may be fully activated last).

[0131] As another example, in an embodiment in which there may be three pre-reactors, a first stage and a second stage of catalyst activation may occur such that the most downstream pre-reactor of the pre-reactor group may first activate its catalyst material, then the pre-reactor downstream of the first pre-reactor may secondly activate its catalyst material, and the most upstream pre-reactor may next activate its catalyst material, and then the downstream layer of catalyst material of the tubes of furnace F201 may be activated to complete the second stage of catalyst activation.

[0132] The activation sequence of different catalyst materials in the downstream layer and upstream layer of catalyst material in the furnace tube and the catalyst material of the pre-reactor can be configured to occur so that those elements reach different higher temperatures at a desired activation rate over a period of time, which is set to promote the complete activation of the catalyst material without causing sintering of the catalyst material. The total temperature of each reactor and furnace required for the catalyst activation of the target sequence may depend on the type of catalyst material used. In some embodiments, the temperature curve can be controlled so that the higher temperature points of different elements match the desired sequence of catalyst activation. For example, the upstream portion of the furnace F201 can first reach the desired final activation temperature for the complete activation of the upstream portion of the catalyst material in the tube of the radiation section 89 of the furnace F201. Then, the temperature of the second pre-reactor C142 can reach the desired final activation temperature for the complete activation of the catalyst material of the pre-reactor. Then, the first pre-reactor C141 can reach the desired final activation temperature for the complete activation of the catalyst material of the pre-reactor. Finally, the temperature of the downstream portion of the tube of the radiation section with the second downstream layer of catalyst material can reach its desired final activation temperature for the complete activation of the catalyst material. In such an embodiment, the temperature of the downstream portion of the catalyst material of the furnace tube can be higher than the other activation temperatures (e.g., can be between 500° C. and 700° C., or between 600° C. and 650° C., etc.). The other activation temperatures can be approximately the same or vary between different desired temperatures (e.g., the temperature can vary between 300° C. and 450° C., or between 350° C. and 500° C., etc.).

[0133] Figure 2 Also shown is an exemplary embodiment of a catalyst activation method, which may include a first catalyst activation stage and a second catalyst activation stage. Figure 2 It can be seen that in the first step S1, hydrogen or other first reactants can be fed to activate the catalyst material in the upstream reactor (e.g., pre-reactors C141 and C142) and the furnace (e.g., furnace F201) downstream of the reactor. Hydrogen can be fed during the first catalyst activation stage of the first step S1 until it is determined that the upstream section of the catalyst material in the furnace F201 is in a first preselected activation condition (e.g., it is determined that the furnace F201 has a condition in which the furnace is at a first preselected temperature and / or a first preselected concentration of hydrogen is detected in one or more tubes of the radiation section 89 of the furnace F201, etc.). Complete activation of the catalyst material can include removal of a coating of the catalytic material (e.g., complete removal of an oxide coating the entire outer surface of the catalytic material, complete removal of a passivation layer covering the entire outer surface of the catalytic material, etc.).

[0134] In the second step S2, ammonia can be fed into the apparatus as a second reactant to be directed as a reactant into the furnace and upstream reactors (e.g., pre-reactor C141, pre-reactor C142, etc.) to replace the first reactant (e.g., hydrogen) for continued activation of the catalyst material in the furnace downstream of the reactor, so that the lower activity catalyst in the furnace can be fully activated.

[0135] In some embodiments, the feeding of the first reactant comprising hydrogen in the first step S1 and the feeding of the second reactant comprising ammonia in the second step S2 can be performed so that the higher activity portion of the catalyst material in the furnace is fully activated first, the higher activity catalytic material in the second reactor (e.g., the second pre-reactor C142) of the upstream reactor downstream of the first reactor (e.g., the first pre-reactor C141) of the upstream reactor is fully activated second, the catalytic material in the first reactor of the upstream reactor is fully activated third, the lower activity catalytic material in the second reactor is activated fourth, and the lower activity portion of the catalytic material in the furnace is fully activated last. Ammonia can be fed as pure ammonia or as ammonia diluted with nitrogen, and can be used in the second step S2 to fully activate the lower activity portion of the catalytic material in the furnace. The first step S1 can be performed to fully activate other catalyst materials (for example, a higher activity portion of the catalyst material in the furnace through the first step S1 is fully activated, a higher activity catalytic material in the second reactor (for example, the second pre-reactor C142) of the upstream reactor downstream of the first reactor (for example, the first pre-reactor C141) of the upstream reactor of the first step S1 is secondly fully activated, a catalytic material in the first reactor of the upstream reactor of the first step S1 is thirdly fully activated, and a lower activity catalytic material in the second reactor of the first step S1 is fourthly activated).

[0136] In other embodiments, the feed of a first reactant comprising hydrogen can be carried out so that the catalytic material within one or more pre-reactors occurs first in a first step and the furnace having tubes with less active catalyst material is finally fully activated by the feed of a second reactant comprising ammonia in a second step S2.

[0137] In other embodiments, the feeding of the first reactant may be performed to fully activate the catalyst material first in the one or more pre-reactors, and when present, fully activate the more active catalyst material in the tubes of the furnace. Then, the second reactant may be fed to the pre-reactors and the furnace tubes to finally fully activate the less active catalyst in the tubes of the furnace to complete the full catalyst activation of the catalyst material. Then, the third step S3 may be performed for the ammonia cracking operation.

[0138] As described above, it is contemplated that in some embodiments, the feed of ammonia may also include recycling the ammonia reactant of the second reactant to the reactor and furnace and other elements (e.g., a heat exchanger) for catalyst activation. The application of heat and the feed of ammonia during the second step S2 may be provided so that complete activation of the furnace and reactor catalytic materials may occur in a predetermined order by the feed of ammonia to help avoid sintering of the catalytic materials. In addition, as described above, the first reactant containing hydrogen that was previously used for the initial first stage of catalyst activation may be removed, while the second reactant containing ammonia (e.g., by exhausting the first reactant) is utilized for the transition between the first stage and the second stage of catalyst activation.

[0139] In the third step S3, after the downstream section of the catalytic material of the furnace that may have a lower activity catalytic material (e.g., when the downstream portion of the catalytic material includes a Ni-based catalyst that is less active than the upstream portion of the catalytic material including a Ru-based catalyst, the downstream portion of the catalytic material of the tube of the radiant section 89 of the furnace F201) is fully activated, ammonia can be fed into the reactor and the furnace to crack the ammonia and form at least one hydrogen product stream for downstream use of the ammonia cracking system (e.g., transported to a remote customer via a pipeline or vehicle, fed to a device connected to the ammonia cracking system for hydrogen use, etc.). The feed rate of ammonia provided during the third step S3 can be substantially greater than the feed of ammonia that occurs during the second stage of catalyst activation that can occur during the second step S2. This process can result in the cessation of any venting or reduction of venting, the non-use of the reactant circulation conduit arrangement, and the selective use of the first portion 44 of the exhaust gas stream 42 to serve as a fuel source for the furnace and / or the second portion 46 of the exhaust gas stream 42 for further enhanced hydrogen recovery via the hydrogen recovery unit U501 as described above.

[0140] We have found that conducting a second stage of catalyst activation so that the less active downstream layer of the catalyst material of furnace F201 is activated last can facilitate temperature control during the catalyst activation process, which can avoid the prolonged use of excessively high temperatures for catalyst activation of other upstream equipment, so that various upstream equipment can be avoided from being exposed to excessive temperatures. For example, the temperature profile that preheat heat exchangers E310, E311, E312, E2102, E2103, and E305 may be exposed to can be minimized by such a catalyst activation sequence.

[0141] For example, we surprisingly found that control of the temperature profile in furnace F201 can drive the temperature of the catalyst activation process, which is at least in part due to the recycling of reactants during the catalyst activation process. In the case where the higher activation temperature catalyst material in the furnace is activated before other upstream equipment can be activated, the temperature of the furnace can be relatively high and cause the output reactant gas and flue gas flow to be at too high a temperature when being transferred to other elements of the heat exchanger (for example, the reactant gas is recycled to the pre-reactor). We have found that this may cause the heat exchanger to be exposed to temperatures that may exceed 600°C, and may far exceed the typical design ratings of the heat exchanger equipment. During the catalyst activation sequence, this type of temperature condition at a relatively low flow rate for the reactant gas flow preheated by the heat exchanger can cause the heat exchanger and conduits through which the flue gas and hot reactant gas flow pass to be exposed to much higher temperatures in a large part of the catalyst activation process. We also found that this type of temperature profile problem may be an important determining factor in the layout compared to other catalyst materials used in the device, where the catalyst material with a very high activation temperature is positioned in the tube of the furnace F201.

[0142] We surprisingly found that controlling the temperature of the reactants during staged catalyst activation to control catalyst activation so that the lower activity catalyst material layer of furnace F201 is activated last can avoid exposing the heat exchanger to high temperature flue gas and reactant flow for a long time, which can avoid the problem of excessive high temperature exposure. This can also allow embodiments to be provided with more conventional equipment, which can provide more design flexibility, maintenance flexibility and reduced capital costs and avoid production delays that may be associated with obtaining more specialized equipment.

[0143] Embodiments also allow catalyst activation to occur without adverse sintering of the catalyst material, while removing oxides and / or passivation layers from the catalyst material for complete activation of the catalyst material. The first catalyst activation stage and the second catalyst activation stage can be controlled so that the temperature during each stage is incrementally increased according to a predefined catalyst activation scheme. For example, as described above, the temperature control can be adopted via the passage of an activation reactant (e.g., hydrogen, ammonia, etc. mixed with nitrogen).

[0144] We have also found that the use of ammonia as a second reactant in the second stage of catalyst activation can also provide a cooling source for the entire system (e.g., to provide a cooling effect with the sensible heat, latent heat, endothermic reaction of ammonia cracking to form nitrogen and hydrogen during the catalyst activation process, etc.), which can reduce the need for other cooling media / equipment during catalyst activation (e.g., cooling water tower / air cooler load savings). Ammonia passed during the second stage of the catalyst activation process can be cracked in the pre-reactor due to the heat to produce hydrogen and nitrogen, which can be provided to the upstream catalyst layer in the tubes of the radiant section 89 of the furnace F201, where the ammonia can be further cracked therein, while being used as a reactant to provide more hydrogen for activation of the downstream portion of the catalyst material in the tubes of the radiant section 89 of the furnace F201. The ammonia feed rate during activation can be significantly lower than the design rate for ammonia cracking, so that a higher conversion amount can occur via the pre-reactor than the design point of the ammonia cracking operation (e.g., about 40%-50% conversion, while 20%-30% conversion under the design conditions for ammonia cracking). Since most of the ammonia used as the second reactant can be converted in the pre-reactor during the second stage of catalyst activation, the temperature in the furnace tubes can be quickly increased to the desired activation temperature because there may be little or no endothermic heat from the ammonia cracking reaction to consume the heat generated by the burner of furnace F201. This can allow the activation process to occur more quickly while also providing the desired temperature regulation in a staged method for catalyst activation, which can also avoid sintering of the catalyst material covered by the passivation layer.

[0145] After the catalyst material used in the ammonia cracking device 1 is fully activated so that the catalyst material is fully activated (for example, the passivation layer has been completely removed from the catalyst material), the ammonia reactant stream can be discharged to remove impurities (for example, water, etc.) from the activation process. The ammonia cracking operation can then be started by feeding liquid ammonia at an ammonia cracking feed rate to produce hydrogen by ammonia cracking (for example, as described above). For example, the ammonia cracking operation can utilize an ammonia stream as described above for feeding ammonia through the tubes of the first pre-reactor, the second pre-reactor, and the radiation section 89 of the furnace F201 for ammonia cracking to produce hydrogen, and then feeding the cracked gas to the hydrogen recovery unit U501 to form a hydrogen product stream 40.

[0146] It should be understood that the catalyst material that can be used in one or more pre-reactors and tubes of the radiation section 89 of the furnace F201 can be any number of suitable catalyst materials for ammonia cracking. The catalyst material may include a supported catalyst as well as an unsupported catalyst. The catalyst material may include a catalyst containing Ni, Ru and / or other suitable elements that can help promote the cracking of ammonia into hydrogen and nitrogen. The shape of the catalyst material may also include any of many suitable shapes, including irregularly shaped catalyst particles, spherical catalyst particles, tubular catalyst particles, polygonal catalyst particles, or catalyst particles of other shapes for the catalyst material. The bed of catalyst material of the reactor and / or tube of the radiation section 89 of the furnace F201 may include a collection of granular catalyst particles, which are positioned so that ammonia can pass through the bed to contact, for example, catalyst particles or other types of catalyst materials.

[0147] It should also be understood that other modifications may also be made to meet the specific standard set of different embodiments of the device 1 or method. For example, the arrangement of valves, pipes and other conduit elements (for example, conduit connection mechanism, pipe, seal, valve, etc.) for the fluid communication of the fluid flow between different elements (for example, pumps, compressors, fans, valves, conduits, etc.) for interconnecting different units of the device can be arranged to meet the specific device layout design considering the available area of ​​the device, the dimensional equipment of the device and other design considerations. For example, the size of each reactor, heat exchanger and / or furnace and the size and configuration of any adsorber, adsorption system, heat exchanger, conduit, expander, pump or compressor can be modified to meet a specific set of design standards. As another example, the flow rate, pressure and temperature of the fluid through one or more heat exchangers and / or reactors and / or at least one furnace and through other device elements can be changed to consider different device design configurations and other design standards. As another example, the number of device units and how they are arranged can be adjusted to meet a specific set of design standards. As another example, the material composition of the different structural components and devices of the units of the device can be any type of suitable material that may be needed to meet a set of specific design standards.

[0148] As yet another example, in some embodiments, it is contemplated that a single reactant containing only ammonia (e.g., ammonia, ammonia mixed with nitrogen, etc.) may be used for catalyst activation. The ammonia used may be liquid ammonia, which is evaporated, optionally mixed with nitrogen, and subsequently passed through one or more pre-reactors and at least one tube having catalyst material therein and positioned in the radiation section 89 of the furnace F201 to activate the catalyst material. Catalyst material activation may occur within a pre-selected time period according to a pre-selected activation scheme to provide full activation of all catalyst materials within the temperature rating of various equipment according to a pre-defined catalyst activation scheme. In some embodiments, such activation may be provided by the use of at least some recirculation of ammonia, while additional liquid ammonia is also added to the reactant feed to provide catalyst activation, and the temperature at different pre-reactors / furnace tubes and heat exchangers is also controlled to provide a series of catalyst activations, so that the catalyst material with the highest activation temperature in the tube of the furnace is activated last, while other catalyst materials are activated before the highest activation temperature catalyst material in the tube of the furnace.

[0149] Embodiments of our apparatus 1 and methods may each be configured to include process control elements positioned and configured to monitor and control operations (e.g., temperature and pressure sensors, flow sensors, an automated process control system having at least one workstation including a processor, non-volatile memory, and at least one transceiver for communicating with the sensor elements, valves, and a controller for providing a user interface for the automated process control system that may be run at the workstation and / or another computer device at the plant, etc.). It should be appreciated that embodiments may also utilize a distributed control system (DCS) to implement one or more processes and / or control operations on the apparatus.

[0150] As another example, it is contemplated that specific features described individually or as part of an embodiment may be combined with other individually described features or parts of other embodiments. Thus, the elements and actions of the different embodiments described herein may be combined to provide other embodiments. Thus, while certain exemplary embodiments of our methods, devices, systems, and methods of making and using the same have been shown and described above, it should be clearly understood that the invention is not limited thereto, but may be implemented and practiced in other ways within the scope of the appended claims.

Claims

1. A method for activating a catalyst for ammonia cracking, the method comprising: feeding a first reactant comprising hydrogen to at least one pre-reactor positioned upstream of the furnace having at least one tube in the radiant section of the furnace such that the first reactant passes through the catalyst material of the at least one pre-reactor and subsequently through the catalyst material of the at least one tube in the radiant section of the furnace, In response to detecting a first level of catalyst activation, feeding the first reactant is stopped and feeding a second reactant comprising ammonia is started to the at least one pre-reactor and the at least one tube within the radiant section of the furnace such that the second reactant passes through the catalyst material of the at least one pre-reactor and subsequently through the at least one tube within the radiant section of the furnace to fully activate the catalyst material of the at least one tube.

2. The method according to claim 1, wherein: The feeding of the first reactant and the feeding of the second reactant occur so that the catalyst material in the upstream portion of the at least one tube is fully activated, then the catalyst material of the at least one pre-reactor is fully activated, and then after the catalyst material of the at least one pre-reactor is fully activated and after the catalyst material in the upstream portion of the at least one tube is fully activated, the catalyst material in the downstream portion of the at least one tube is fully activated.

3. The method according to claim 1, wherein: The feeding of the second reactant comprising ammonia occurs such that the catalyst material in the downstream portion of the at least one tube is finally fully activated.

4. The method according to claim 1, comprising: mixing nitrogen with the ammonia of the second reactant so that the second reactant has a preselected ammonia concentration of ammonia and / or the second reactant has a preselected flow rate; and / or The nitrogen gas is mixed with the hydrogen gas of the first reactant such that the first reactant has a preselected hydrogen concentration of hydrogen and / or the first reactant has a preselected flow rate.

5. The method according to claim 1, wherein: The at least one prereactor comprises the first prereactor having catalyst material within a vessel of the first prereactor and the second prereactor having catalyst material within a vessel of a second prereactor, the second prereactor being downstream of the first prereactor such that the second prereactor is between the at least one tube of the furnace and the first prereactor.

6. The method according to claim 5, wherein: The feeding of the first reactant occurs such that: (a) the catalyst material in the upstream portion of the at least one tube is fully activated; (b) the catalyst material of the second pre-reactor is fully activated; and (c) the catalyst material of the first pre-reactor is fully activated, and wherein the feeding of the second reactant occurs such that: (d) the catalyst material in the downstream portion of the at least one tube is fully activated.

7. The method according to claim 6, wherein: The catalyst material of the downstream portion of the at least one tube has a higher activation temperature than the catalyst material of the upstream portion of the at least one tube.

8. The method according to claim 7, wherein: The catalyst material of the downstream portion of the at least one tube has a higher activation temperature than the catalyst material of the first pre-reactor.

9. The method according to claim 8, wherein: The catalyst material of the downstream portion of the at least one tube has a higher activation temperature than at least some of the catalyst material of the second pre-reactor.

10. The method according to claim 1, wherein: The feeding of the first reactant includes recirculating the first reactant through the at least one tube and the at least one pre-reactor for a first period of time.

11. The method according to claim 1, comprising: In response to detecting the first level of catalyst activation, the first reactant is discharged simultaneously with the second reactant commencing to be fed toward the at least one pre-reactor and the at least one tube.

12. An apparatus for ammonia cracking configured to promote catalyst activation, the apparatus comprising: a furnace having at least one tube including a catalyst material for cracking ammonia within the at least one tube, the catalyst material within the at least one tube having an upstream portion of catalyst material and a downstream portion of catalyst material; and at least one pre-reactor, the at least one pre-reactor being positioned upstream of the at least one tube, the at least one tube being in fluid communication with the at least one pre-reactor; The device is sized and configured such that: A first reactant may be fed to the at least one pre-reactor and the at least one tube such that the first reactant passes through the catalyst material of the at least one pre-reactor and then through the catalyst material of the at least one tube, and A second reactant may be fed to the at least one pre-reactor and the at least one tube such that, in response to detecting a first level of catalyst activation, the first reactant is dischargeable and the second reactant may be fed to the at least one pre-reactor and the at least one tube such that the second reactant may pass through the catalyst material of the at least one pre-reactor and subsequently through the at least one tube to fully activate at least some of the catalyst material of the at least one tube.

13. The device according to claim 12, wherein: The apparatus is configured so that the feeding of the first reactant occurs such that the upstream portion of the catalyst material of the at least one tube is fully activated first and then the catalyst material of the at least one pre-reactor is fully activated, and The second reactant can be fed to the at least one tube and the at least one pre-reactor such that the downstream portion of the catalyst material of the at least one tube is fully activated after the catalyst material of the at least one pre-reactor is fully activated and after the upstream portion of the catalyst material of the at least one tube is fully activated.

14. The apparatus according to claim 12, wherein: The apparatus is configured such that the feeding of the second reactant occurs such that the downstream portion of the catalyst material of the at least one tube is ultimately fully activated.

15. The apparatus according to claim 12, wherein: The at least one prereactor comprises the first prereactor having catalyst material within a vessel of the first prereactor and the second prereactor having catalyst material within a vessel of a second prereactor, the second prereactor being downstream of the first prereactor such that the second prereactor is between the at least one tube of the furnace and the first prereactor.

16. The device according to claim 15, wherein: The apparatus may be configured such that feeding of the first reactant occurs such that: (a) said upstream portion of said catalyst material of said at least one tube is fully activated; (b) the catalyst material of the second pre-reactor is fully activated; and (c) the catalyst material of the first pre-reactor is fully activated, and The feeding of the second reactant occurs such that: (d) the catalyst material in the downstream portion of the catalyst material of the at least one tube is fully activated.

17. The device according to claim 16, wherein: The downstream portion of the catalyst material of the at least one tube has a higher activation temperature than the catalyst material of the upstream portion of the catalyst material of the at least one tube.

18. The apparatus according to claim 17, wherein: the downstream portion of the catalyst material of the at least one tube has a higher activation temperature than the catalyst material of the first pre-reactor, and wherein the catalyst material of the downstream portion of the at least one tube has a higher activation temperature than at least some of the catalyst material of the second pre-reactor.

19. The apparatus according to claim 12, wherein: A reactant recirculation conduit arrangement is included that is positioned so that the first reactant from the outlet of the at least one tube can be recirculated to the at least one pre-reactor.

20. An apparatus for ammonia cracking configured to promote catalyst activation, the apparatus comprising: a furnace having at least one tube including a catalyst material for cracking ammonia within said at least one tube, said catalyst material within said at least one tube having a higher activity portion of said catalyst material that is more active than a lower activity portion of said catalyst material; and at least one pre-reactor, the at least one pre-reactor being positioned upstream of the at least one tube, the at least one tube being in fluid communication with the at least one pre-reactor; The device is sized and configured such that: A first reactant may be fed to the at least one pre-reactor and the at least one tube such that the first reactant passes through the catalyst material of the at least one pre-reactor and then through the catalyst material of the at least one tube, and A second reactant may be fed to the at least one pre-reactor and the at least one tube such that, in response to detecting a first level of catalyst activation, the first reactant is dischargeable and the second reactant may be fed to the at least one pre-reactor and the at least one tube such that the second reactant may pass through the catalyst material of the at least one pre-reactor and subsequently through the at least one tube to fully activate the less active portion of the catalyst material of the at least one tube.

Images