Method for cracking ammonia gas and cracking device for cracking ammonia gas

Abstract

The invention relates to a method for cracking ammonia gas, comprising:-feeding a first portion of the ammonia gas into a burner (14) arranged in a cracking vessel (12); -feeding an oxygen-containing gas into the burner (14); -combusting a first portion of the ammonia gas, forming a combustion zone (101) in the cracking vessel (12), generating heat; feeding a second portion of the ammonia gas into a cracking zone (102) of the cracking vessel (12) outside the combustion zone (101); and-cracking the second portion of the ammonia gas with heat generated by combustion of the first portion of the ammonia gas and generating a product gas comprising hydrogen and nitrogen from the second portion of the ammonia gas. The invention also relates to a cracking device (10) for cracking ammonia gas.

Description

Technical Field

[0001] The invention relates to a method for cracking ammonia and a cracking device for cracking ammonia. Background Art

[0002] Despite its toxicity, ammonia is considered a promising candidate for a carbon-free fuel and / or hydrogen carrier. Excess energy in one location can be used to produce NH3, which can be transported to locations where energy is needed. The energy in NH3 can be utilized by direct combustion or cracking into H2. At high temperatures, and in the presence of a suitable catalyst, ammonia cracks into its constituent elements. Cracking of ammonia is a slightly endothermic process that requires 23 kJ / mol (5.5 kcal / mol) of ammonia and produces hydrogen and nitrogen.

[0003] As an example of using NH3 as a hydrogen carrier and the hydrogen contained in NH3, reference is made to US 6936363. This document discloses a process for generating a mixture of hydrogen and nitrogen from gaseous ammonia and utilizing the mixture in an alkaline fuel cell. The ammonia is fed into an ammonia cracker. The exhaust gas from the fuel cell is fed to a heating unit of the ammonia cracker. The heating unit is a lean gas combustion chamber or a catalytic burner.

[0004] Conventional plants for decomposing molecular compounds require high temperature heat due to the endothermic nature of the process. The source of this energy is usually electricity for small scale and combustion of NH3 or fossil fuels for large scale, and the heat is transferred to the NH3 fed in. This heat transfer takes place at high temperatures, placing stringent demands on the heat exchangers.

[0005] The object of the present invention is to provide a method and a cracking device for cracking ammonia, wherein the improvements lie in their simple construction and efficient operation. Summary of the invention

[0006] The objects of the invention are substantially met as disclosed in the independent claim and in the other claims describing more details of different embodiments of the invention.

[0007] According to the present invention, a method for cracking ammonia comprises:

[0008] - feeding a first portion of the ammonia gas into a burner arranged in the cracking vessel;

[0009] - feeding oxygen-containing gas into the burner;

[0010] - burning the first portion of the ammonia to form a combustion zone in the cracking vessel to generate heat;

[0011] - feeding a second portion of the ammonia into a cracking zone of a cracking vessel outside the combustion zone, and

[0012] - utilizing the heat generated by the combustion of the first part of the ammonia to crack the second part of the ammonia and to generate a product gas comprising hydrogen and nitrogen from the second part of the ammonia.

[0013] According to one aspect of the present invention, in the combustion zone, the first portion of the ammonia gas consumes the introduced oxygen to form a non-oxidizing zone outside the combustion zone in the cracking vessel.

[0014] According to one aspect of the invention, the second portion of the ammonia gas is cracked in the presence of an ammonia cracking catalyst.

[0015] According to one aspect of the invention, in the combustion zone, the first portion of ammonia consumes the oxygen fed, a non-oxidation zone is formed outside the combustion zone in the cracking vessel, and the second portion of ammonia is cracked in the presence of an ammonia cracking catalyst.

[0016] According to one aspect of the invention, the second portion of the ammonia gas is cracked using a non-catalytic reaction.

[0017] According to one aspect of the present invention, in the combustion zone, the first part of the ammonia consumes the oxygen fed, and a non-oxidation zone is formed outside the combustion zone in the cracking vessel and the second part of the ammonia is cracked using a non-catalytic reaction.

[0018] According to one aspect of the invention, a first portion of ammonia and oxygen-containing gas are fed into the burner as a gas mixture.

[0019] According to one aspect of the invention, the ammonia is preheated before being fed to the burner by heat transfer from the product gas to the gas mixture.

[0020] According to one aspect of the invention, the ammonia is vaporized before being fed to the burner by heat transfer from the product gas to the gas mixture.

[0021] According to one aspect of the invention, the container has a cylindrical internal reaction space having a diameter and a length, the length being greater than the diameter, wherein a first portion of ammonia and oxygen-containing gas is fed into the reaction space of the container at a first end in the longitudinal direction of the container, and product gas is taken off from a second end of the reaction space of the cracking container.

[0022] According to one aspect of the present invention, the second part of the ammonia gas is heated to a predetermined temperature by heat provided by combustion of the first part of the ammonia gas, and the heated second part of the ammonia gas is sent to the cracking catalyst under non-oxidative conditions.

[0023] According to one aspect of the invention, a combustion zone is formed on the central axis of the cracking vessel, and at least a portion of the second portion of ammonia gas is fed from the first end of the space in the vessel into the periphery of the combustion zone.

[0024] According to one aspect of the invention, at least a portion of the second portion of ammonia gas is introduced into the container near a side wall of the space in the container between the first end and the second end thereof.

[0025] According to one aspect of the invention, at least a portion of the second portion of ammonia gas is introduced into the cracking zone in the vicinity of the vessel wall.

[0026] According to one aspect of the present invention, the oxygen-containing gas is a mixture of NH 3 and an oxygen-containing gas.

[0027] According to one aspect of the present invention, the oxygen-containing gas is air.

[0028] According to one aspect of the invention, the oxygen-containing gas is pure O2.

[0029] According to one aspect of the present invention, for example, the ammonia cracking catalyst is a nickel-based catalyst, a ruthenium-based catalyst, a lithium amide or a sodium amide-based catalyst.

[0030] According to one aspect of the invention, the combustion zone temperature is maintained at about 800°C to 1800°C.

[0031] According to one aspect of the invention, the temperature in the cracking zone is maintained at 350°C to 800°C by combustion of the first portion of the ammonia gas in the combustion zone of the vessel.

[0032] According to one aspect of the invention, the amount of oxygen present in the combustion zone is controlled so that all of the oxygen reacts with the ammonia.

[0033] According to one aspect of the invention, the oxygen-containing gas is a mixture of NH 3 and air, and the air-fuel ratio in the combustion zone is rich.

[0034] According to one aspect of the invention, the product gas is fed from the reaction space into the oxidant section, wherein the product gas is oxidized by feeding an oxygen-containing gas into the product gas stream.

[0035] A cracking device for cracking ammonia according to the present invention comprises:

[0036] a cracking vessel and a burner arranged to the cracking vessel, the burner comprising a first inlet for feeding ammonia gas into the burner and a second inlet for feeding an oxygen-containing gas into the burner, and

[0037] The product gas outlet in the cracking vessel is characterized in that

[0038] The cracking vessel is a cylindrical vessel, wherein the burner is arranged at a first end of the vessel, arranged on the central axis of the vessel, and the outlet is arranged at a second end of the space of the vessel,

[0039] The cleavage vessel further comprises a third inlet for feeding ammonia gas into the cleavage vessel, arranged near the side wall and / or near the first end of the space in the vessel.

[0040] According to one aspect of the invention, the cracking vessel interior includes an open space including a combustion zone adjacent to a burner at a first end of the vessel and a cracking zone at a second end of the space in the vessel and around the burner.

[0041] According to one aspect of the invention, the container is provided with an ammonia cracking catalytic converter in the cracking zone at the second end of the space in the container.

[0042] According to one aspect of the present invention, a catalytic converter includes at least one of a bulk material catalyst bed, a catalyst support coated with a catalyst material, or a catalyst coating on an inner surface of a container.

[0043] According to an aspect of the invention, the third inlet comprises several inlets into the internal reaction space of the container, the several inlets being arranged around the burner on the end wall at the first end of the space in the container.

[0044] According to an aspect of the invention, the third inlet comprises a plurality of inlets arranged near the side wall of the container at a distance from the end wall at the first end of the space in the container.

[0045] According to an aspect of the invention, the vessel comprises an oxidant section arranged downstream of the pyrolysis zone and the oxidant section is provided with at least one inlet for an oxygen-containing gas.

[0046] The present invention provides several benefits. Since the basic concept is to mix both the NH3 to be cracked and the combustion gases in a single container, heat is mixed directly to the NH3 to be cracked. The NH3 to be cracked is heated by internal combustion inside the container. Since heat is transferred by mixing, convective heat transfer and radiation, efficient heat transfer between the combustion gases and the NH3 is achieved.

[0047] The exemplary embodiments of the invention presented in this patent application should not be interpreted as imposing limitations on the applicability of the appended claims. The verb "comprise" is used in this patent application as an open limitation that does not exclude the presence of unrecited features. Unless explicitly stated otherwise, the features recited in the dependent claims are freely combinable with each other. The novel features regarded as characteristic of the invention are particularly set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In the following, the present invention will be described with reference to the accompanying exemplary, schematic drawings, in which

[0049] Figure 1 A cracking device according to an embodiment of the present invention is shown.

[0050] Figure 2 A cracking device according to another embodiment of the present invention is shown.

[0051] Figure 3 A cracking device according to another embodiment of the present invention is shown.

[0052] Figure 4 A cracking device according to another embodiment of the present invention is shown.

[0053] Figure 5 A cracking device according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0054] Figure 1 A cracking device 10 for cracking ammonia according to an embodiment of the present invention is schematically depicted. The device comprises a cracking vessel 12. The cracking vessel 12 is advantageously a rotationally symmetrical (e.g. cylindrical) container having a longitudinal central axis 16. When the container is cylindrical, the length of the internal reaction space 100 of the container is greater than the diameter of the container. A burner 14 is arranged at a first end 12.1 of the reaction space 100 of the container 12 for fuel combustion. The cracking vessel 12 is provided with an outlet 18 for product gas in a second end 12.2 of the reaction space 100 of the container 12 opposite to the burner 14. Even if shown in the figure as such, the outlet 18 is not necessarily arranged on the central axis 16.

[0055] However, the burner 14 is arranged on the central axis 16 of the container so that its flame is coaxial with the central axis 16 inside the container 12. The burner 14 includes a first inlet 20 connected to an ammonia source 22 for feeding ammonia as fuel into the burner 14, and a second inlet 24 connected to an oxygen-containing gas source 26 for feeding oxygen-containing gas into the burner 14. The first inlet 20 and the second inlet 24 are used to introduce the gas required to generate heat for cracking ammonia in the container 12.

[0056] The cracking vessel 12 further comprises a plurality of third inlets 28 for feeding ammonia into the cracking vessel 12, arranged on the side wall 30 and / or the end wall 32 at the first end 12.1 of the space 100 in the vessel. The third inlets 28 are used to introduce ammonia into the cracking vessel 12 for cracking the ammonia by means of heat generated by combustion of the gas by the burner 14.

[0057] The reaction space 100 inside the cracking vessel 12 is an open space 100, wherein a combustion zone 101 adjacent to the burner 14 is formed when the burner 14 is in operation, and a cracking zone 102 is in a portion of the space 100 at the second end 12.2 of the space 100 of the vessel 12. The combustion zone 101 can be considered as a flame region where fuel oxidation occurs in the presence of oxygen. The diameter of the space of the container at its first end 12.1 is larger than the effective diameter of the flame (i.e., the combustion zone 101), so the annular portion around the combustion zone 101 is part of the cracking zone 102. Since the container is intended to operate at a relatively high temperature, its wall is preferably provided with a heat insulation and / or cooling system (similar to a fluid jacket).

[0058] Advantageously, the vessel 12 comprises a number of third inlets 28 arranged uniformly around the burner 14 on the end wall 32 at the first end of the space 100 of the vessel. These inlets 28 at the end wall 32 are arranged to feed ammonia gas to the annular cracking zone 102 around the burner. Advantageously, there are a number of third inlets 28 arranged at the side wall 30 of the vessel at a distance from the end wall 32 at the first end 12.1 of the space 100 of the vessel 12. The third inlets 28 are positioned so that the ammonia gas introduced via the third inlets 28 is heated by combustion in the burner in the space 100. The cracking zone 102 outside the combustion zone 101 is in fact a non-oxidizing zone. A control valve 34 may be arranged in connection with each of the inlets and inlet channels suitable for balancing the gas flow.

[0059] exist Figure 1 In the embodiment shown, the space 100 is empty. When the space 100 is empty, the cracking reaction is non-catalytic thermal cracking, so Figure 1 The cracking zone 102 in the embodiment of the present invention may be referred to as a non-catalytic cracking zone 102. Alternatively, the inner wall of the adjacent space 100 may be provided with a catalyst coating on its surface, wherein the catalyst will promote the cracking reaction in the container 12.

[0060] The method for cracking ammonia is based on Figure 1 The invention is practiced in the following manner in a cracking vessel of the invention. Ammonia is fed into the burner 14 from an ammonia source 22 and an oxygen-containing gas is also fed into the burner 14. A first portion of the ammonia is burned in the burner 14, wherein heat is generated in the vessel 12 and a combustion zone 101 is formed in the cracking vessel 12. The first portion of the ammonia is fed via a first inlet 20 and the oxygen-containing gas is fed into the burner 14 via a second inlet 24. The oxygen-containing gas fed via the first inlet 20 may be air or another oxygen-containing gas or even pure O2.

[0061] The combustion of ammonia generally follows the following reaction:

[0062] 4NH3+3O2->2N2+6H2O

[0063] The combustion of ammonia is an exothermic reaction that generates heat and consumes oxygen in the container. Therefore, the combustion of the first portion of ammonia forms a substantially oxygen-free region (ie, non-oxidizing region 102) outside the combustion zone in the container.

[0064] The second portion of ammonia gas is fed into the cracking zone 102 of the cracking vessel 12 outside the combustion zone 101 via the third inlet 28, wherein the second portion of ammonia gas is thermally cracked using the heat generated by the combustion of the first portion of ammonia gas. Figure 5 As shown, the second portion of ammonia can come from a different ammonia source than the first portion of ammonia. This also applies technically to Figures 1 to 4 The embodiment shown.

[0065] The cracking of ammonia generally follows the following reaction:

[0066] 2NH3->3H2+N2

[0067] The resulting product gas generated from the second portion of ammonia thus comprises hydrogen and nitrogen. In this embodiment, the space in the vessel is empty and the cracking is a non-catalytic reaction.

[0068] Gas resulting from the cracking and combustion of the ammonia is directed from vessel 12 via outlet 18 for the desired use of the product gas.

[0069] More precisely, a first portion of ammonia and oxygen-containing gas is fed into the space 100 of the container at a first end 12 . 1 in the longitudinal direction of the container, and product gas is taken off from a second end of the space of the cleavage container 12 .

[0070] The second portion of ammonia is heated to a predetermined temperature at which ammonia is cracked without any catalyst. Heat is provided by the combustion of the first portion of ammonia, and the heated second portion of ammonia is cracked under non-oxidative conditions in the empty cracking zone 102. Because heat is transferred by mixing, convective heat transfer, and radiation, efficient heat transfer between the combustion gas and the ammonia in the cracking zone is provided.

[0071] By burning the first portion of ammonia, the combustion zone temperature is maintained at 800°C to 1800°C, and the cracking zone temperature is maintained at 350°C to 800°C. In some practical cases, the temperature may be higher, but spontaneous cracking will occur when the NH3 temperature approaches 800°C. The cracking reaction itself is an endothermic reaction that cools the gas. A catalyst is required to support cracking in the lower temperature range.

[0072] Since the burner is arranged on the central axis 16, the combustion zone 101 is also formed on the central axis 16 of the cracking vessel 12, and advantageously, at least a portion of the second part of the ammonia gas is fed in from the first end wall 32 of the vessel 12 around the combustion zone 101, meaning also around the burner 14. At least a portion of the second part of the ammonia gas is fed in longitudinally between the combustion zone and the cracking zone 102 through the side wall 30 of the vessel. In this way, the space of the vessel and the thermal effect of the combustion zone are effectively used for the cracking reaction.

[0073] Advantageously, the amount of oxygen present in the combustion zone is controlled so that all of the oxygen reacts with the ammonia in the combustion zone to provide a non-oxidative cracking zone 102 in the vessel 12. Advantageously, the oxygen-containing gas is air and the air-fuel ratio in the combustion zone is rich. In this way, it is ensured that all of the oxygen present in the combustion zone 101 is consumed. This also means that a portion of the first portion of ammonia fed to the burner may remain as ammonia. Even if the burner may produce ammonia slip, the remaining ammonia will be cracked into hydrogen and nitrogen in the cracking zone 102.

[0074] Figure 2 A cracking device 10 for cracking ammonia according to another embodiment of the present invention is disclosed. Figure 1 2, except that the first and second inlets are combined into a common gas inlet 24' so that the oxygen-containing gas fed to the burner 14 is a mixture of NH3 and oxygen-containing gas. Figure 2 In the embodiment of the invention, both the oxygen-containing gas source 26 and the ammonia gas source 22 are connected to a common gas inlet 24'. This makes it easier to control the operation of the burner and to preheat the two gases as a mixture in a more direct manner.

[0075] Figure 3 A cracking device 10 for cracking ammonia according to another embodiment of the present invention is disclosed. Figure 1 Similar to that shown, except that the first and second inlets are as Figure 2 The pyrolysis zone 102 is shown combined into a common gas inlet 24' and includes an ammonia catalytic converter 103 in the zone.

[0076] The common second outlet 24' causes the oxygen-containing gas fed to the burner 14 to be a mixture of NH3 and oxygen-containing gas. Figure 2 In the embodiment of the invention, both the oxygen-containing gas source 26 and the ammonia gas source 22 are connected to a common gas inlet 24'. This makes it easier to control the operation of the burner and to preheat the two gases as a mixture in a more direct manner.

[0077] The catalytic converter 103 is arranged from the third inlet 28 arranged on the side wall 30 of the container 12 to the second end of the space in the container (on the outlet side of the container 12). In this way, the second part of the ammonia gas is cracked in the presence of the ammonia cracking catalyst.

[0078] Here, the catalytic converter 103 is shown as a support grid with catalyst material arranged on its surface. The catalytic converter can also be arranged in a different manner, for example alternatively comprising a bed of loose material with catalyst on its surface, such as Figure 4 As shown. As an example of utilizing the present invention, currently considered suitable catalyst materials are: nickel-based, ruthenium-based, lithium amide or sodium amide catalysts. Each catalyst is effective at temperatures of 350°C to 800°C. However, the conversion efficiency and expected life span vary.

[0079] The second portion of ammonia is heated to a predetermined temperature at which ammonia cracking occurs without any catalyst. Heat is provided by combustion of the first portion of ammonia, and the heated second portion of ammonia is fed to a cracking catalyst under non-oxidizing conditions.

[0080] Figure 4 A cracking device 10 for cracking ammonia according to another embodiment of the present invention is schematically depicted. The device comprises a cracking vessel 12, which is advantageously a rotationally symmetrical vessel (e.g. cylindrical) having a longitudinal central axis 16. When the vessel is cylindrical, the length of the internal reaction space 100 of the vessel is greater than the diameter of the vessel.

[0081] Advantageously, the vessel 12 is in an upright position so that the central axis 12 is arranged substantially in a vertical position. In this way, the flame and heat distribution in the vessel are advantageously formed symmetrically about the central axis 16. The burner 14 is arranged at the lower end 12.1 of the vessel 12 to facilitate the combustion of the fuel. The cracking vessel 12 is provided with an outlet 18 for the product gas in the upper end 12.2 of the vessel 12 opposite to the burner 14.

[0082] The burner 14 is arranged on the central axis 16 of the container so that its flame is directed upwards coaxially with the central axis 16 inside the container 12. The burner 14 comprises a combined second inlet 24', which is connected to the surrounding air 26, the ammonia source 22 and the pressurized oxygen source 26', for feeding a mixture of oxygen-enriched air and ammonia into the burner 14. The oxygen source is not an essential feature of the present invention, and when it is not present, the gas mixture fed into the burner consists essentially of air and ammonia. The combined second inlet 24' is used to introduce the gases required to generate heat for cracking ammonia in the container 12.

[0083] The cracking vessel 12 further comprises a plurality of third inlets 28 for feeding ammonia gas into the cracking vessel 12, arranged on or near the side wall 30 and / or the end wall 32 at the first end 12.1 of the space 100 in the vessel. The third inlets 28 are used to introduce ammonia gas into the cracking vessel 12 for cracking the ammonia gas by means of heat generated by combustion of the gas by the burner 14.

[0084] The cracking vessel 12 includes an open space 100 inside, wherein a combustion zone 101 adjacent to the burner 14 is formed when the burner 14 is in operation, and a cracking zone 102 is in a portion of the space 100 at a second end 12.2 of the space in the vessel 12. The diameter of the space 100 in the vessel at its first end 12.1 is larger than the effective diameter of the flame (i.e., the combustion zone 101), so the annular portion around the combustion zone 101 is a portion of the cracking zone 102.

[0085] Advantageously, the vessel 12 comprises third inlets 28 arranged uniformly around the burner 14 on the end wall 32 at the first end of the space 100 of the vessel. Similar to other embodiments of the invention, these inlets 28 at the end wall 32 are arranged to feed ammonia into the annular cracking zone 102 formed around the burner. Advantageously, there are several third inlets 28 arranged on the side wall 30 of the vessel at a distance from the end wall 32 at the first end 12.1 of the space 100 in the vessel 12. The third inlets 28 are positioned so that the ammonia introduced via the third inlets 28 is heated by combustion in the burner and is in a non-oxidizing zone in the space 100. The third inlets at the side wall are connected to a feed channel 27, which is arranged in direct heat transfer communication with the annular cracking zone 102, which preheats the ammonia due to heat transfer from the gas and / or flame in the space 100. The feed channel 27 extending inside the vessel is an optional feature. If preheating is not required in process design, the feed channel 27 may also extend outside the container 12, such as Figures 1 to 3 . For example, the feed channel can actually be realized by providing an annular groove channel inside the container 12 between the container wall and the sleeve or shield 29 inside the container 12, as shown in dotted lines. The cracking zone 102 outside the combustion zone 101 is actually a non-oxidizing zone. A control valve 34 can be arranged in connection with each of the inlet and inlet channels, suitable for balancing the gas flow.

[0086] exist Figure 1 and Figure 2 In the embodiment shown, in the combustion zone 101 and the upper part of the container 12, the space 100 is empty, and Figure 3 In the embodiment shown, a catalytic converter 103 is disposed in the upper portion of the space 100. Figure 4, an embodiment is shown in which a catalytic converter 103 is arranged in the upper part of the space 100. In practice, both options (using a catalyst or not using a catalyst) can be used according to the desired design, but it is preferred to use a catalyst because the cracking of ammonia is carried out at a lower temperature, which leads to a reduction in heat losses and consumption of ammonia as fuel, thereby reducing the H2 yield from the available ammonia. Figure 4 The cracking reaction in the embodiment shown is catalytic thermal cracking, so Figure 1 The cracking zone 102 in the embodiment of can be referred to as a catalytic cracking zone 102.

[0087] A gas mixture feed line 25 is provided in the device 10, which is connected to the burner 14, more precisely, to the combined second inlet 24' at the second end of the feed line 25. The first end of the feed line 25 is connected to an ammonia source 22. In this example, the ammonia source is configured to store ammonia in liquid phase. The feed line 25 is provided with a pump 23 for increasing the pressure of the ammonia to a suitable pressure.

[0088] according to Figure 4 The cracking device also includes a heat recovery device 36 (e.g., a heat exchanger) connected to the feed line 25 and the outlet line 38, which uses the heat contained in the product gas to evaporate the ammonia. The container outlet 18 is connected to the heat recovery device 36 via the outlet line 38, so that the product gas is arranged to be cooled in the heat recovery device 36, and the ammonia is arranged to evaporate in the heat recovery device 36. Therefore, the heat recovery device 36 serves as an aftercooler for the process gas and an evaporator for the ammonia. In this way, the ammonia is evaporated and preheated by heat transfer from the product gas to the gas mixture before being fed to the burner. There is a branch feed line 21 connected to the feed line 25 at a downstream position of the heat recovery device 36, so that the evaporated ammonia is arranged to flow through the branch feed line 21 to the third inlet 28 of the container 12. The term downstream refers to the flow direction from the ammonia source 22 to the container 12.

[0089] The apparatus further comprises an air feed line 40, which is configured to feed air in ammonia into the gas mixture feed line 25. The air feed line is provided with a compressor 42 for appropriately pressurizing the air, alternatively, the air feed line 40 can be connected to a pressurized air source. The air feed line is connected to the gas mixture feed line 25 at a position downstream of the heat recovery device 36 and downstream of the branch feed line 21 that delivers ammonia to the third inlet 28 of the container 12. Optionally, the air feed line 40 is connected to an oxygen source 26', and pure oxygen can be fed into the air from the oxygen source 26', so that the oxygen-containing gas fed into the burner 14 is a mixture of ammonia, air and pure oxygen.

[0090] The method for cracking ammonia is based on Figure 4The process is carried out in the following manner in a cracking vessel of the invention. Ammonia is fed from an ammonia source 22 into a gas mixture feed line 25 by suction of a pump 23. The pump 23 raises the pressure of the ammonia to a desired level and feeds the ammonia (liquid phase) into a heat recovery device 36. Ammonia evaporates in the heat recovery device 36 by heat transfer from the product gas. A portion of the evaporated ammonia is fed to a third inlet 28 of the vessel 12 via a branch feed line 21.

[0091] Air (optionally enriched with oxygen) is fed into the gaseous ammonia stream after the heat recovery device 36. The mixture of ammonia and air (optionally enriched with oxygen) is fed to the burner 14 via the gas mixture feed line 25. In this way, a first portion of the ammonia is burned in the burner 14, wherein heat is generated in the vessel 12 and a combustion zone 101 is formed in the cracking vessel 12.

[0092] Combustion of ammonia and cracking of ammonia in the cracking vessel 12 and other operating features of the cracking vessel 12 are combined Figure 1 The description is used to describe, which also applies to Figure 4 implementation method.

[0093] Figure 5 A cracking device 10 for cracking ammonia according to another embodiment of the present invention is disclosed. The present invention relates to practical applications in which the product gas is not intended to be produced for use, but is merely a gas converted into components that are less harmful to the environment. In fact, the cracking device 10 is similar to Figure 1 The differences shown are as follows. The first and second inlets are combined into a common gas inlet 24' so that the oxygen-containing gas fed to the burner 14 is a mixture of NH3 and oxygen-containing gas. In other words, both the oxygen-containing gas source 26 and the ammonia source 22 are connected to the common gas inlet 24' of the burner 14. In addition, the cracking vessel 12 is provided with an oxidant portion 104 after the cracking zone 120 in the flow direction of the gas in use. In addition, at least a portion of the wall of the vessel 12 is cooled. Figure 5 The embodiment of the invention is also different in that the gas mixture feed pipeline 25 is connected to the first ammonia source 22 (corresponding to Figures 1 to 4 The second ammonia source 22' may be a source of ammonia in the embodiment of the present invention, such that a first portion of ammonia is fed to the burner 14. The second portion of ammonia is derived from a second ammonia source 22', which may be different from the source of ammonia that feeds the first portion of ammonia to the burner 14. Thus, in this embodiment, the combustion gas used in the burner 14 may have a different composition than the ammonia-containing gas cracked in the cracking zone 102 of the vessel. For example, the second ammonia source 22' may be an ammonia fuel line connected to a gas consumer (e.g., an internal combustion engine) during the process of inerting the fuel line with nitrogen.

[0094] The vessel 12 comprises a fluid jacket 44, which is arranged to cool the vessel by circulating a cooling fluid (e.g., water) therein. To this end, the fluid jacket 44 is provided with a fluid inlet 46 and a fluid outlet 48. In the cracking vessel 12, the cracking zone 102 is provided with an outlet 18', which forms a contraction to the cross-sectional area of ​​the cracking zone 102. As shown, the contraction is preferably conical on both sides of the contraction, thereby smoothly separating the cracking zone and the oxidant portion 104. The oxidant portion 104 is provided with one or more oxidant inlets 50 connected to the oxygen-containing gas source 26 via a flow channel 52. The flow channel leads to an annular groove 54 radially arranged on the outside of the sleeve 29. The annular groove 54 is formed between the inner wall of the vessel 12 and the second sleeve 56. The second sleeve 56 extends from the end wall 32 to the outlet 18', so that the groove 54 has a substantially constant radial width. The slots and second sleeve 56 extending axially further from the end wall 32 than the sleeve 29 are arranged in direct heat transfer communication with the cracking zone 102 to preheat the gas due to heat transfer from the gas and / or flame in the space 100. The flow channel 52 is preferably arranged without direct heat transfer connection with the fluid jacket 44 or the cooling wall of the vessel 12. The oxygen-containing gas source 26 is connected to the flow channel 52. As shown, the oxygen-containing gas source 26 connected to the flow channel 52 can be different from the oxygen-containing gas source connected to the burner 14 to improve the controllability of the burner 14. The oxidant inlet 50 opens into the space in the oxidant section 104 near the outlet 18' of the cracking zone.

[0095] As described in other embodiments, burner 14 burns ammonia and provides heat for cracking, and the ammonia is cracked in cracking zone 102. Product gas from cracking zone 102 is fed to oxidant section 104 and, because the gas temperature is above its natural temperature, autoignites in the presence of oxygen.

[0096] Ammonia 22 and combustion air 26 are premixed and swirled in the burner inlet 14, ignited and produce a rich (i.e., excess) fuel flame 101. This flame will provide heat for ammonia cracking 102. Exhaust gas (preferably a mixture of ammonia and nitrogen) from the process of inerting the fuel line with nitrogen (second ammonia source 22') (the exhaust composition will vary) is injected into the annular space between the side wall 30 and the inner shield 29 and is heated as it flows to the cracking zone 102. There, the heat from the combustion will decompose the ammonia into nitrogen and hydrogen. Since it is a rich fuel, there is no air available to burn the hydrogen. The exhaust gas composed of N2, NO, NO2 and H2 will leave the cracking zone 102 stage through the outlet 18', where air is supplied through the inlet 50, mixed with hydrogen and ignited by the hot surface. The outlet area is made of high temperature resistant material, is not cooled by the cooling fluid, and the mixture will be burned in the oxidant section 104. The downstream exhaust gas will consist of N2, H2O and trace amounts of NO and NO2 (in the 10-15 ppm range).

[0097] Although the invention is described herein as an example in conjunction with what is currently considered the most preferred embodiment, it is obvious to a skilled person that, as technology advances, the basic idea of ​​the invention can be implemented in many ways. The invention and its embodiments are therefore not limited to the examples and samples described above, but they can be varied within the content of the patent claims and their legal equivalents. Details mentioned in conjunction with any of the above embodiments can be used in conjunction with another embodiment when the combination is technically feasible.

[0098] Parts List

[0099] Cracking device 10

[0100] Cracking vessel 12

[0101] First end of the space in the container 12.1 Second end of the space in the container 12.2 Burner 14

[0102] The central axis 16 of the cracking vessel and the outlet 18

[0103] First entrance 20

[0104] Branch feed line 21

[0105] Ammonia source 22

[0106] Pump 23

[0107] Second entrance 24

[0108] Public gas inlet 24'

[0109] Gas mixture feed pipeline 25 Oxygen-containing gas source 26

[0110] Pressurized oxygen source 26'

[0111] Feed channel 27

[0112] Third entrance 28

[0113] Sleeve 29

[0114] Side wall 30

[0115] End wall 32

[0116] Valve 34

[0117] Heat recovery equipment36

[0118] Export pipeline 38

[0119] Air feed line 40

[0120] Compressor 42

[0121] Fluid Jacket 44

[0122] Fluid inlet 46

[0123] Fluid outlet 48

[0124] Oxidant inlet 50

[0125] Oxidant flow channel 52

[0126] The inner space of the container is 100

[0127] Burning Zone 101

[0128] Cracking zone 102

[0129] Ammonia cracking catalytic converter 103

[0130] Oxidant section 104

Claims

1. A method for cracking ammonia, the method comprising the following steps: - feeding a first portion of the ammonia gas into a burner (14) arranged in the cracking vessel (12); - feeding an oxygen-containing gas into the burner (14); - burning the first portion of ammonia gas with the burner (14) to form a combustion zone (101) in the cracking vessel (12) and generate heat; - feeding a second portion of the ammonia gas into the cracking zone (102) of the cracking vessel (12) outside the combustion zone (101), and - utilizing heat generated by combustion of the first portion of ammonia to crack the second portion of ammonia and to generate a product gas comprising hydrogen and nitrogen from the second portion of ammonia.

2. The method for cracking ammonia according to claim 1, characterized in that: In the combustion zone (101), the first portion of ammonia consumes the oxygen introduced, thereby forming a non-oxidation zone outside the combustion zone (101) in the cracking vessel (12).

3. The method for cracking ammonia according to claim 1 or 2, characterized in that: The second portion of the ammonia gas is cracked in the presence of an ammonia cracking catalyst (103).

4. The method for cracking ammonia according to claim 1 or 2, characterized in that: The second portion of the ammonia is cracked using a non-catalytic reaction.

5. The method for cracking ammonia according to claim 1, characterized in that: The first portion of ammonia and the oxygen-containing gas are fed into the burner (14) as a gas mixture.

6. The method according to claim 1, characterized in that Ammonia is preheated before being fed into the burner (14) by heat transfer from the product gas to the gas mixture.

7. A method for cracking ammonia according to any one of the preceding claims, wherein: The container (12) has a cylindrical inner reaction space (100) having a diameter and a length, the length being greater than the diameter, characterized in that the first portion of ammonia and the oxygen-containing gas are fed into the reaction space (100) of the container (12) at a first end (12.1) in the longitudinal direction of the container, and the product gas is taken away from the second end (12.2) of the reaction space (100) of the cracking container (12).

8. The method for cracking ammonia according to claim 3 or 7, characterized in that: The second part of the ammonia gas is heated to a predetermined temperature by heat provided by combustion of the first part of the ammonia gas, and the heated second part of the ammonia gas is sent to the cracking catalyst under non-oxidizing conditions.

9. A method for cracking ammonia according to any one of the preceding claims, characterized in that The combustion zone (101) is formed on the central axis (16) of the cracking vessel (12), and at least part of the second portion of ammonia gas is introduced around the combustion zone (101) from the first end (12.1) of the space (100) in the vessel (12).

10. A method for cracking ammonia according to any one of the preceding claims, characterised in that At least a portion of the second portion of ammonia gas is introduced into the container (12) between a first end (12.1) and a second end (12.2) of the space (100) in the container (12) near a side wall of the container.

11. The method according to any one of the preceding claims, characterized in that The oxygen-containing gas is a mixture of NH 3 and oxygen-containing gas.

12. The method according to any one of the preceding claims 1 to 9, characterized in that The oxygen-containing gas is air.

13. The method according to any one of the preceding claims 1 to 9, characterized in that The oxygen-containing gas is pure O2.

14. The method according to claim 3, characterized in that The ammonia cracking catalyst is selected from the group consisting of a nickel-based catalyst, a ruthenium-based catalyst, a lithium amide or a sodium amide-based catalyst.

15. The method according to any one of the preceding claims, characterized in that The temperature of the combustion zone (101) is maintained at 800°C to 1800°C.

16. The method according to any one of the preceding claims, characterized in that The temperature in the cracking zone (102) is maintained at 350°C to 800°C by combustion of the first portion of ammonia gas in the combustion zone (101) of the container (12).

17. The method according to any one of the preceding claims, characterized in that The amount of oxygen present in the combustion zone (101) is controlled so that all of the oxygen reacts with the ammonia.

18. The method according to claim 12, characterized in that The air-fuel ratio in the combustion zone (101) is rich.

19. The method according to any one of the preceding claims, characterized in that From the reaction space (100) the product gas is fed into an oxidant section (104) where it is oxidized by feeding an oxygen-containing gas into the flow of the product gas.

20. A cracking device (10) for cracking ammonia, the device comprising: A cracking vessel (12) and a burner (14) arranged in an open space (100) inside the cracking vessel (12), the burner (14) comprising a first inlet (20) for feeding ammonia gas into the burner (14) and a second inlet (24) for feeding oxygen-containing gas into the burner (14), and The outlet (18) for the product gas in the cracking vessel (12) is characterized in that The cracking vessel (12) is a cylindrical vessel (12), wherein the burner (14) is arranged at a first end (12.1) of the space (100) in the vessel (12), on a central axis (16) of the vessel (12), and the outlet (18) is arranged at a second end (12.2) of the space (100) in the vessel (12), The cracking vessel (12) further comprises a third inlet (28) for feeding ammonia into the cracking vessel (12), wherein the third inlet is arranged near the side wall of the space (100) in the vessel (12) and / or the first end (12.1).

21. The cracking device (10) according to claim 19, characterized in that The open space (100) includes a combustion zone (101) adjacent to the burner (14) at the first end (12.1) of the space (100) in the container (12), and a cracking zone (102) surrounding the burner (14) at the second end (12.2) of the space (100) in the container (12).

22. The lysis container (12) according to claim 19 or 20, characterized in that The container (12) is provided with an ammonia cracking catalytic converter (103) in the cracking zone (102) at the second end (12.2) of the space (100) in the container (12).

23. The lysis container (12) according to claim 20, characterized in that The catalytic converter (103) comprises at least one of a bulk material catalyst bed, a catalyst support coated with a catalyst material, or a catalyst coating on the inner surface of the container (12).

24. The pyrolysis device according to claim 19, characterized in that The third inlet (28) comprises a plurality of inlets into the space (100) inside the container (12), the plurality of inlets being arranged around the burner (14) on an end wall at the first end (12.1) of the space (100) in the container (12).

25. The pyrolysis device according to claim 18 or 23, characterized in that The third inlet (28) comprises a plurality of inlets arranged near a side wall of the container (12) at a distance from the end wall at the first end (12.1) of the space (100) in the container (12).

26. The pyrolysis device according to claim 23, characterized in that The first inlet (20) and the second inlet (24) are formed as a single common gas inlet (24').

27. Lysis device according to claims 23 and 24.

28. The pyrolysis device according to any one of claims 20 to 27, characterized in that The vessel comprises an oxidant section (104) arranged downstream of the pyrolysis zone (102), and the oxidant section (104) is provided with at least one inlet (50) for an oxygen-containing gas.

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