Ammonia decomposition system and method for decomposing ammonia

Abstract

An ammonia decomposition system (100) comprises: a first line (L1) to which ammonia (X1) is supplied; a decomposition device (3) that is provided on the first line (L1) and generates a decomposition gas (X3) containing hydrogen from ammonia (X1); and a second line (L2) that is in fluid communication with the first line (L1) at a position downstream of the decomposition device (3), the second line (L2) supplying liquid ammonia (X2) to the decomposition gas (X3) flowing through the first line (L1) and generating a mixed gas (X4).

Description

Ammonia decomposition system and method for decomposing ammonia

[0001] The present disclosure relates to an ammonia decomposition system and a method for decomposing ammonia. This application claims the benefit of priority from Japanese Patent Application No. 2023-198469, filed November 22, 2023, the contents of which are incorporated herein by reference.

[0002] Ammonia is CO ２ Ammonia is known as a fuel that does not emit CO₂. Ammonia is flame-retardant. Therefore, at least a portion of the ammonia may be decomposed into gases containing hydrogen before combustion. Hydrogen burns more easily than ammonia. However, the decomposition gases from ammonia are hot. Such decomposition gases may cause problems such as nitridation and hydrogen embrittlement of piping.

[0003] For example, Patent Document 1 discloses an ammonia decomposition apparatus. In this ammonia decomposition apparatus, the decomposition gas flowing out from the reactor is cooled in a cooler. The cooler exchanges heat between the liquid ammonia before decomposition and the decomposition gas.

[0004] International Publication No. 2022 / 153719

[0005] As disclosed in Patent Document 1, for example, in order to cool the cracked gas, it is conceivable to provide a cooler such as a heat exchanger in the cracked gas flow path. In this case, a refrigerant supply system is required. Furthermore, the control system becomes complicated in order to control the output of the heat exchanger.

[0006] The present disclosure aims to provide an ammonia decomposition system and method for decomposing ammonia that can cool the decomposition gas from the ammonia.

[0007] An ammonia decomposition system according to one aspect of the present disclosure includes a first line to which ammonia is supplied, a decomposition device provided in the first line and configured to produce a decomposition gas containing hydrogen from ammonia, and a second line fluidly connected to the first line at a position downstream of the decomposition device, the second line supplying liquid ammonia to the decomposition gas flowing through the first line to produce a mixed gas.

[0008] The ammonia decomposition system may include a mixer provided on the first line at a position downstream of the decomposition device, for mixing the decomposition gas from the decomposition device with the liquid ammonia from the second line.

[0009] The ammonia decomposition system may include a tank in fluid communication with the first line and the second line, the tank including a chamber for storing ammonia in two phases including gaseous ammonia and liquid ammonia, the first line connected to an upper portion of the chamber and the second line connected to a lower portion of the chamber.

[0010] The ammonia decomposition system may include a tank in fluid communication with the first line and the second line, the tank supplying liquid ammonia to each of the first line and the second line, and a vaporizer provided in the first line between the tank and the decomposition device, the vaporizer heating the liquid ammonia flowing through the first line to produce gaseous ammonia.

[0011] The ammonia decomposition system may include a first adjuster provided in the first line at a position upstream of the decomposition device and adjusting the flow rate of ammonia flowing through the first line; a second adjuster provided in the second line and adjusting the flow rate of liquid ammonia flowing through the second line; and a control device communicatively connected to the first adjuster and the second adjuster, the control device being configured to: obtain an apparent decomposition rate of a mixed gas of gaseous ammonia decomposed in the decomposition device; obtain a temperature of the mixed gas; and control the first adjuster and the second adjuster so that the apparent decomposition rate does not fall below a predetermined lower limit and so that the temperature of the mixed gas does not exceed a predetermined upper limit.

[0012] A method for decomposing ammonia according to another aspect of the present disclosure includes supplying ammonia to a first line; generating a cracked gas containing hydrogen from the ammonia by a cracker provided in the first line; and supplying liquid ammonia from a second line that is fluidly connected to the first line at a position downstream of the cracker to the cracked gas flowing through the first line, thereby generating a mixed gas.

[0013] According to the present disclosure, the decomposition gas from ammonia can be cooled.

[0014] Fig. 1 is a schematic diagram showing an ammonia decomposition system according to a first embodiment. Fig. 2 is a schematic diagram showing an ammonia decomposition system according to a second embodiment. Fig. 3 is a schematic diagram showing an ammonia decomposition system according to a third embodiment. Fig. 4 is a schematic diagram showing an ammonia decomposition system according to a fourth embodiment. Fig. 5 is a flowchart showing an example of the operation of the ammonia decomposition system according to the fourth embodiment. Fig. 6 is a flowchart showing another example of the operation of the ammonia decomposition system according to the fourth embodiment.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0016] 1 is a schematic diagram showing an ammonia decomposition system 100 according to a first embodiment. In the present disclosure, the ammonia decomposition system may also be simply referred to as a "system." For example, the system 100 includes a first tank (ammonia supply source) 1, a second tank (liquid ammonia supply source) 2, a decomposition device 3, and a mixer 4. The system 100 may further include other components. Also, the system 100 may not include one or more of the above components.

[0017] The first tank 1 stores ammonia. For example, in the present embodiment, the first tank 1 stores gaseous ammonia X1. The first tank 1 is connected to a first line L1. For example, the first line L1 includes one or more pipes. The first tank 1 supplies the gaseous ammonia X1 to the first line L1. For example, the first tank 1 may include a valve, and may supply the gaseous ammonia X1 to the first line L1 at a flow rate corresponding to the valve opening and the pressure in the first tank 1. Alternatively or additionally, the first line L1 may include a compressor and a valve for adjusting the flow rate of the gaseous ammonia X1. For example, in other embodiments, a gaseous ammonia producing apparatus may be used as an ammonia supply source instead of the first tank 1.

[0018] The second tank 2 stores liquid ammonia X2. The liquid ammonia X2 is stored at a low temperature. For example, under atmospheric pressure, the liquid ammonia X2 is stored at a temperature lower than −33° C. The second tank 2 is connected to the second line L2. For example, the second line L2 includes one or more pipes. The second tank 2 supplies liquid ammonia X2 to the second line L2. For example, the second tank 2 may include a valve, and liquid ammonia X2 may be supplied to the second line L2 at a flow rate that depends on the valve opening and the pressure within the second tank 2. Alternatively or additionally, the second line L2 may include a pump and a valve for adjusting the flow rate of the liquid ammonia X2. For example, in other embodiments, a liquid ammonia manufacturing apparatus may be used as a liquid ammonia supply source instead of the second tank 2.

[0019] The decomposition device 3 is provided on the first line L1. The decomposition device 3 is connected to the first tank 1 via the first line L1 and is in fluid communication with the first tank 1. Gaseous ammonia X1 is supplied to the decomposition device 3 from the first tank 1 via the first line L1. The decomposition device 3 generates a cracked gas X3 containing hydrogen from the gaseous ammonia X1 flowing through the first line L1. Note that the cracked gas X3 may contain unreacted ammonia that has not been decomposed.

[0020] For example, the decomposition device 3 may include a heater for heating the ammonia. For example, when the ammonia is heated to about 600 to 800°C, most of the ammonia can be decomposed into hydrogen and nitrogen. In this case, the decomposition gas X3 reaches a high temperature of about 600 to 800°C.

[0021] Alternatively or additionally, the decomposition device 3 may include a catalyst that decomposes ammonia into hydrogen and nitrogen. Generally, the catalyst is inactive below a certain temperature. Therefore, the catalyst is heated to a certain temperature, for example, about 500 to 600°C. In this case, the decomposition gas X3 reaches a high temperature of about 500 to 600°C.

[0022] For example, the catalyst may contain a transition element (which may also be referred to as a transition metal). For example, the catalyst may contain a noble metal such as Ru. Also, for example, the catalyst may contain a non-noble metal such as Fe, Co, Ni, or Cu among the transition elements. Non-noble metals may exhibit high activity when combined with a specific support. Examples of the support include Al. ２ O ３ or SiO ２ Oxides such as CeO may also be used as needed. ２ A carrier capable of suppressing sintering such as may be used.

[0023] The mixer 4 is provided in the first line L1 at a position downstream of the cracking device 3. The mixer 4 is connected to the cracking device 3 via the first line L1 and is in fluid communication with the cracking device 3. The mixer 4 is supplied with cracked gas X3 from the cracking device 3 via the first line L1.

[0024] In this embodiment, the second line L2 is directly connected to the mixer 4. The mixer 4 is connected to the second tank 2 via the second line L2 and is in fluid communication with the second tank 2. The mixer 4 is supplied with liquid ammonia X2 from the second tank 2 via the second line L2. In other embodiments, the second line L2 may be connected to the first line L1 between the decomposition device 3 and the mixer 4.

[0025] The mixer 4 mixes the cracked gas X3 from the cracker 3 with the liquid ammonia X2 from the second line L2. For example, the mixer 4 can be various mixers such as an in-line mixer. As described above, the cracked gas X3 becomes hot. Therefore, the liquid ammonia X2 is vaporized by the heat from the cracked gas. The cracked gas X3 is also cooled by the vaporization of the liquid ammonia X2. As a result, the temperature of the mixed gas X4 produced in the mixer 4 is lower than the temperature of the cracked gas X3 produced in the cracker 3. For example, the mixed gas X4 may contain gaseous ammonia, liquid ammonia, hydrogen, and nitrogen.

[0026] For example, if the temperature of the mixed gas X4 is higher than the intended range, the operator may increase the amount of liquid ammonia by adjusting the opening of the valve of the second tank 2. Alternatively or additionally, the operator may decrease the amount of gaseous ammonia by adjusting the opening of the valve of the first tank 1.

[0027] In contrast, for example, if the temperature of the mixed gas X4 is lower than the intended range, the operator may reduce the amount of liquid ammonia by adjusting the opening of the valve of the second tank 2. Alternatively or additionally, the operator may increase the amount of gaseous ammonia by adjusting the opening of the valve of the first tank 1.

[0028] In another embodiment, the valves of the first tank 1 and the second tank 2 may be fixed to a preset opening so that the temperature of the mixed gas X4 falls within an intended range.

[0029] In this embodiment, the system 100 is applied to a combustion system including an ammonia decomposition system 100 and a combustor 5, and the mixed gas X4 from the system 100 is used as fuel in the combustor 5. For example, the combustor 5 may be used in equipment such as a gas turbine or a boiler. Equipment using the combustor 5 is not limited to these. In other embodiments, the system 100 may be applied to other systems including devices other than the combustor 5.

[0030] The system 100 described above includes a first line L1 to which gaseous ammonia X1 is supplied, a decomposition device 3 provided in the first line L1 and configured to produce a cracked gas X3 containing hydrogen from the gaseous ammonia X1, and a second line L2 fluidly connected to the first line L1 downstream of the decomposition device 3, which supplies liquid ammonia X2 to the cracked gas X3 flowing through the first line L1 to produce a mixed gas X4. A method according to this embodiment includes supplying gaseous ammonia X1 to the first line L1, generating the cracked gas X3 containing hydrogen from the gaseous ammonia X1 using the decomposition device 3 provided in the first line L1, and supplying liquid ammonia X2 from the second line L2 fluidly connected to the first line L1 downstream of the decomposition device 3 to the cracked gas X3 flowing through the first line L1 to produce a mixed gas X4. According to this configuration, the liquid ammonia X2 from the second line L2 is vaporized by heat from the cracked gas X3 from the decomposition device 3. Furthermore, the decomposed gas X3 is cooled by the vaporization of the liquid ammonia X2. As a result, the temperature of the mixed gas X4 is lower than the temperature of the decomposed gas X3 generated in the decomposition device 3. Therefore, the decomposed gas X3 can be cooled.

[0031] The system 100 also includes a mixer 4 that is provided on the first line L1 at a position downstream of the decomposition device 3 and that mixes the cracked gas X3 from the decomposition device 3 with the liquid ammonia X2 from the second line L2. With this configuration, the cracked gas X3 can be cooled more uniformly.

[0032] The system 100 may also include a first tank 1 in fluid communication with the first line L1 and configured to store gaseous ammonia X1, and a second tank 2 in fluid communication with the second line L2 and configured to store liquid ammonia X2.

[0033] Next, other embodiments will be described.

[0034] 2 is a schematic diagram showing an ammonia decomposition system 200 according to a second embodiment. The system 200 differs from the system 100 in that the system 200 includes a third tank 6 instead of the first tank 1 and the second tank 2. The other configurations of the system 200 may be the same as those of the system 100.

[0035] The third tank 6 includes a chamber 61. The chamber 61 stores ammonia in two phases including gaseous ammonia X1 and liquid ammonia X2. The gaseous ammonia X1 is stored in an upper portion of the chamber 61, and the liquid ammonia X2 is stored in a lower portion of the chamber 61.

[0036] The first line L1 is connected to an upper portion of the chamber 61. Therefore, the third tank 6 supplies gaseous ammonia X1 from the chamber 61 to the first line L1. For example, the third tank 6 may include a valve for the first line L1, and may supply gaseous ammonia X1 to the first line L1 at a flow rate corresponding to the valve opening and the pressure in the chamber 61.

[0037] The second line L2 is connected to a lower portion of the chamber 61. Therefore, the third tank 6 supplies liquid ammonia X2 from the chamber 61 to the second line L2. For example, the third tank 6 may include a valve for the second line L2, and may supply liquid ammonia X2 to the second line L2 at a flow rate that corresponds to the opening degree of the valve and the pressure inside the chamber 61.

[0038] The system 200 as described above provides the same effects as the system 100.

[0039] In particular, the system 200 includes a third tank 6 that is fluidly connected to the first line L1 and the second line L2. The third tank 6 includes a chamber 61 that stores ammonia in two phases, including gaseous ammonia X1 and liquid ammonia X2. The first line L1 is connected to an upper portion of the chamber 61, and the second line L2 is connected to a lower portion of the chamber 61. With this configuration, both the gaseous ammonia X1 and the liquid ammonia X2 can be stored in the same third tank 6. This reduces the space and cost required to install the tank.

[0040] 3 is a schematic diagram showing an ammonia decomposition system 300 according to a third embodiment. The system 300 differs from the system 100 in that the system 300 includes a fourth tank (liquid ammonia supply source) 7 and a vaporizer 8 instead of the first tank 1 and the second tank 2. The other configurations of the system 300 may be the same as those of the system 100.

[0041] The fourth tank 7 stores liquid ammonia X2. The fourth tank 7 is connected to both the first line L1 and the second line L2. The fourth tank 7 supplies liquid ammonia X2 to both the first line L1 and the second line L2. Therefore, in this embodiment, the first line L1 is supplied with liquid ammonia X2 instead of gaseous ammonia X1. For example, the fourth tank 7 may include valves for each of the first line L1 and the second line L2, and may supply liquid ammonia X2 to each of the first line L1 and the second line L2 at a flow rate corresponding to the valve opening and the pressure within the fourth tank 7.

[0042] The vaporizer 8 is provided on the first line L1 between the fourth tank 7 and the decomposition device 3. The vaporizer 8 is connected to the fourth tank 7 via the first line L1 and is in fluid communication with the fourth tank 7. Liquid ammonia X2 is supplied to the vaporizer 8 from the fourth tank 7 via the first line L1. The vaporizer 8 heats the liquid ammonia X2 flowing through the first line L1 to generate gaseous ammonia X1. Note that the gaseous ammonia X1 may contain liquid ammonia that has not been vaporized. For example, the vaporizer 8 may use a fluid having a higher temperature than the liquid ammonia X2, such as exhaust gas from the combustor 5 or seawater, as the heat medium. The vaporizer 8 is connected to the decomposition device 3 via the first line L1 and is in fluid communication with the decomposition device 3. The vaporizer 8 supplies gaseous ammonia X1 to the decomposition device 3 via the first line L1.

[0043] The system 300 as described above provides the same effects as the system 100.

[0044] In particular, the system 300 includes a fourth tank 7 fluidly connected to the first line L1 and the second line L2, the fourth tank 7 supplying liquid ammonia X2 to each of the first line L1 and the second line L2, and a vaporizer 8 provided in the first line L1 between the fourth tank 7 and the decomposition device 3, the vaporizer 8 heating the liquid ammonia X2 flowing through the first line L1 to generate gaseous ammonia X1. With this configuration, liquid ammonia X2 can be supplied from the same fourth tank 7 to both the first line L1 and the second line L2. This allows for a reduction in the space and cost required for installing tanks.

[0045] 4 is a schematic diagram showing an ammonia decomposition system 400 according to a fourth embodiment. The system 400 differs from the system 100 described above in that the system 400 includes a first adjuster A1, a second adjuster A2, a temperature sensor S, and a control device 90. The rest of the configuration of the system 400 may be the same as that of the system 100.

[0046] The first adjuster A1 is provided in the first line L1 at a position upstream of the decomposition device 3, between the first tank 1 and the decomposition device 3 in this embodiment. The first adjuster A1 adjusts the flow rate of the gaseous ammonia X1 flowing through the first line L1. For example, the first adjuster A1 may include a flow controller capable of measuring the flow rate of the gaseous ammonia X1 and adjusting the flow rate of the gaseous ammonia X1. Alternatively or additionally, for example, the first adjuster A1 may include a flow meter and at least one valve. The first adjuster A1 is communicatively connected to the control device 90 and transmits measurement data to the control device 90. The control device 90 is configured to adjust the flow rate of the gaseous ammonia X1 flowing through the first line L1 by controlling the first adjuster A1.

[0047] The second adjuster A2 is provided in the second line L2. In the present embodiment, the second adjuster A2 is provided between the second tank 2 and the mixer 4. The second adjuster A2 adjusts the flow rate of the liquid ammonia X2 flowing through the second line L2. For example, the second adjuster A2 may include a flow controller capable of measuring and adjusting the flow rate of the liquid ammonia X2. Alternatively or additionally, for example, the second adjuster A2 may include a flow meter and at least one valve. The second adjuster A2 is communicatively connected to the control device 90 and transmits measurement data to the control device 90. The control device 90 is configured to adjust the flow rate of the liquid ammonia X2 flowing through the second line L2 by controlling the second adjuster A2.

[0048] The temperature sensor S is provided on the first line L1 at a position downstream of the connection position (mixer 4) with the second line L2, in this embodiment, between the mixer 4 and the combustor 5. The temperature sensor S measures the temperature of the mixed gas X4 flowing through the first line L1. The temperature sensor S is connected to the control device 90 so as to be able to communicate with the control device 90, and transmits measurement data to the control device 90.

[0049] The control device 90 controls all or part of the system 400. The control device 90 may also control the combustor 5, and may further control the entire combustion system including the system 400 and the combustor 5. For example, the control device 90 may be configured with one or more PCs. The control device 90 includes components such as a processor 90a, a storage device 90b, and a connector 90c, which are connected to each other via a bus. For example, the processor 90a includes a central processing unit (CPU). For example, the storage device 90b includes a hard disk, a ROM for storing programs and the like, and a RAM as a work area. The control device 90 is connected to each component of the system 400 and the combustor 5 via the connector 90c so as to be able to communicate with them via wired or wireless communication. For example, the control device 90 may further include other components, such as a display device such as a liquid crystal display or a touch panel, and an input device such as a keyboard, buttons, or a touch panel. For example, the following operation of the control device 90 may be realized by the processor 90a executing a program stored in the storage device 90b.

[0050] The control device 90 is communicatively connected to the decomposition device 3 and controls the output of the decomposition device 3. The control device 90 can adjust the decomposition rate in the decomposition device 3 by controlling the output of the decomposition device 3. In the present disclosure, the "decomposition rate" may be defined as the ratio of the amount of gaseous ammonia X1 decomposed in the decomposition device 3 to the amount of gaseous ammonia X1 flowing into the decomposition device 3. For example, the control device 90 may store in advance in the storage device 90b a map or equation indicating the relationship between the output of the decomposition device 3, the flow rate of gaseous ammonia X1, and the decomposition rate. These maps or equations indicate the decomposition rate depending on the output of the decomposition device 3 and the flow rate of gaseous ammonia X1. Furthermore, for example, the control device 90 may store in advance in the storage device 90b a map or equation indicating the relationship between the output of the decomposition device 3, the flow rate of gaseous ammonia X1, and the temperature of the decomposition gas X3 at the outlet of the decomposition device 3. These maps or equations indicate the temperature of the decomposition gas X3 depending on the output of the decomposition device 3 and the flow rate of gaseous ammonia X1. For example, these maps and equations may be determined by experiment or analysis.

[0051] For example, the control device 90 may calculate the decomposition rate R1 at the outlet of the decomposition device 3 and the amount FG1 of the gaseous ammonia X1 decomposed in the decomposition device 3 based on the output of the decomposition device 3, the flow rate FG0 of the gaseous ammonia X1 received from the first adjuster A1, and a stored map or formula. The control device 90 may also calculate the temperature T1 of the decomposed gas X3 at the outlet of the decomposition device 3 based on the output of the decomposition device 3, the flow rate FG0 of the gaseous ammonia X1, and a stored map or formula.

[0052] The control device 90 may calculate the amount FL1 of gaseous ammonia vaporized from the liquid ammonia X2 in the mixer 4 and the temperature T2 of the mixed gas X4 at the outlet of the mixer 4 based on the flow rate FG0 of the gaseous ammonia X1, the amount FG1 of the decomposed gaseous ammonia X1, the temperature T1 of the decomposed gas X3, and the flow rate FL0 of the liquid ammonia X2 received from the second adjuster A2.

[0053] The control device 90 may calculate an apparent decomposition rate R2 of the mixed gas X4 based on the flow rate FG0 of the gaseous ammonia X1, the amount FG1 of the decomposed gaseous ammonia X1, and the amount FL1 of the gaseous ammonia vaporized from the liquid ammonia X2. In the present disclosure, the "apparent decomposition rate" may be defined as the ratio of the amount of gaseous ammonia X1 decomposed in the decomposition device 3 to the sum of the amount of gaseous ammonia X1 flowing into the decomposition device 3 and the amount of liquid ammonia X2 flowing into the mixer 4. The apparent decomposition rate R2 correlates with the concentration of hydrogen in the mixed gas X4.

[0054] For example, the flow rate of liquid ammonia X2 can be increased to reduce the temperature T1 of the decomposition gas X3. However, excessively increasing the flow rate of liquid ammonia X2 increases the amount of gaseous ammonia vaporized from the liquid ammonia X2 in the mixer 4. Therefore, the concentration of gaseous ammonia in the mixed gas X4 increases, and the concentration of hydrogen in the mixed gas X4 decreases. That is, the apparent decomposition rate R2 of the mixed gas X4 decreases. This leads to a decrease in the combustibility of the mixed gas X4. Therefore, the control device 90 may adjust the flow rates of gaseous ammonia X1 and liquid ammonia X2 by controlling the first adjuster A1 and the second adjuster A2 so that the temperature T2 of the mixed gas X4 received from the temperature sensor S or the temperature T2 of the mixed gas X4 calculated as described above does not exceed a predetermined upper limit and so that the apparent decomposition rate R2 calculated as described above does not fall below a predetermined lower limit.

[0055] FIG. 5 is a flowchart showing an example of the operation of the ammonia decomposition system 400 according to the fourth embodiment.

[0056] For example, when the total fuel supplied to the combustor 5 (the output of the combustor 5) is increased in a state in which the flow rate of the gaseous ammonia X1 is restricted, the system 400 may operate as shown in Fig. 5. For example, the operation shown in Fig. 5 may be initiated when the system 400 receives a command to increase the output of the combustor 5. For example, in this state, the temperature T2 of the mixed gas X4 received from the temperature sensor S or the calculated temperature T2 of the mixed gas X4 is equal to or lower than the upper limit value, and the calculated apparent decomposition rate R2 is equal to or higher than the lower limit value.

[0057] The processor 90a calculates the target flow rate of the liquid ammonia X2 required for the target output of the combustor 5 based on the target output of the combustor 5 and the flow rate FG0 of the gaseous ammonia X1 (step S100). For example, the processor 90a may calculate the difference in output between the target output and the output of the combustor 5 obtained by the gaseous ammonia X1 at the flow rate FG0, and calculate the flow rate of the liquid ammonia X2 required to obtain the calculated difference in output.

[0058] The processor 90a calculates the apparent decomposition rate R2 based on the target flow rate of the liquid ammonia X2 calculated in step S100 and the flow rate FG0 of the gaseous ammonia X1 (step S102). As described above, the processor 90a can calculate the apparent decomposition rate R2 using a map or formula stored in the storage device 90b.

[0059] The processor 90a determines whether the apparent decomposition rate R2 calculated in step S102 is within a predetermined allowable range (step S104). For example, the control device 90 may store the allowable range in the storage device 90b in advance, and the processor 90a may determine whether the calculated apparent decomposition rate R2 is within the allowable range stored in the storage device 90b. In particular, the processor 90a may determine whether the apparent decomposition rate R2 is below a lower limit value.

[0060] If the apparent decomposition rate R2 is within the allowable range in step S104 (YES), the processor 90a controls the second adjuster A2 to increase the flow rate FL0 of the liquid ammonia X2 to the target flow rate calculated in step S100 (step S106), and then ends the operation. Note that when the flow rate FL0 of the liquid ammonia X2 is increased, the temperature T2 of the mixed gas X4 decreases. Therefore, the temperature T2 of the mixed gas X4 does not exceed the upper limit.

[0061] In step S104, if the apparent decomposition rate R2 is not within the allowable range (NO), the processor 90a ends the operation. In this case, for example, the control device 90 may notify the operator by displaying or sounding the message that the output of the combustor 5 cannot be increased to the target output.

[0062] FIG. 6 is a flowchart showing another example of the operation of the ammonia decomposition system 400 according to the fourth embodiment.

[0063] For example, when the total fuel supplied to the combustor 5 (the output of the combustor 5) is increased while the flow rate of the liquid ammonia X2 is restricted, the system 400 may operate as shown in Fig. 6. For example, the operation shown in Fig. 6 may be initiated when the system 400 receives a command to increase the output of the combustor 5. For example, in this state, the temperature of the mixed gas X4 received from the temperature sensor S or the calculated temperature T2 of the mixed gas X4 is equal to or lower than the upper limit value, and the calculated apparent decomposition rate R2 is equal to or higher than the lower limit value.

[0064] The processor 90a calculates the target flow rate of the gaseous ammonia X1 required for the target output of the combustor 5 based on the target output of the combustor 5 and the flow rate FL0 of the liquid ammonia X2 (step S200). For example, the processor 90a may calculate the difference in output between the target output and the output of the combustor 5 obtained by the liquid ammonia X2 at the flow rate FL0, and calculate the flow rate of the gaseous ammonia X1 required to obtain the calculated difference in output.

[0065] The processor 90a calculates the temperature T2 of the mixed gas X4 at the outlet of the mixer 4 based on the target flow rate of the gaseous ammonia X1 calculated in step S200 and the flow rate FL0 of the liquid ammonia X2 (step S202). As described above, the processor 90a can calculate the temperature T2 using a map or an equation stored in the storage device 90b.

[0066] The processor 90a determines whether the temperature T2 of the mixed gas X4 calculated in step S202 is within a predetermined allowable range (step S204). For example, the control device 90 may store the allowable range in advance in the storage device 90b, and the processor 90a may determine whether the calculated temperature T2 is within the allowable range stored in the storage device 90b. In particular, the processor 90a may determine whether the temperature T2 does not exceed an upper limit value.

[0067] In step S204, if the temperature T2 of the mixed gas X4 is within the allowable range (YES), the processor 90a controls the first adjuster A1 to increase the flow rate FG0 of the gaseous ammonia X1 to the target flow rate calculated in step S200 (step S206), and then ends the operation. Note that when the flow rate FG0 of the gaseous ammonia X1 is increased, the apparent decomposition rate R2 also increases. Therefore, the apparent decomposition rate R2 does not fall below the lower limit value.

[0068] In step S204, if the temperature T2 of the mixed gas X4 is not within the allowable range (NO), the processor 90a ends the operation. In this case, for example, the control device 90 may notify the operator by displaying or sounding the message that the output of the combustor 5 cannot be increased to the target output.

[0069] The system 400 as described above provides the same effects as the system 100 .

[0070] In particular, the system 400 includes a first adjuster A1 provided in the first line L1 upstream of the decomposition device 3 and configured to adjust the flow rate FGO of gaseous ammonia X1 flowing through the first line L1, a second adjuster A2 provided in the second line L2 and configured to adjust the flow rate FL0 of liquid ammonia X2 flowing through the second line L2, and a control device 90 communicably connected to the first adjuster A1 and the second adjuster A2. The control device 90 is configured to obtain an apparent decomposition rate R2 of the mixed gas X4 of the gaseous ammonia X1 decomposed in the decomposition device 3, obtain a temperature T2 of the mixed gas X4, and control the first adjuster A1 and the second adjuster A2 so that the apparent decomposition rate R2 does not fall below a predetermined lower limit and the temperature T2 of the mixed gas X4 does not exceed a predetermined upper limit. This configuration allows the combustibility of the mixed gas X4 to be maintained while cooling the decomposed gas X3.

[0071] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0072] For example, in the above embodiments, the systems 100, 200, 300, and 400 include a mixer 4 in the first line L1. In other embodiments, the systems may include an injector instead of the mixer 4. The injector is connected to the second line L2 and is provided in the first line L1 at a position downstream of the decomposition device 3. The injector injects liquid ammonia into the decomposition gas X3 flowing through the first line L1.

[0073] Furthermore, for example, in system 400 according to the fourth embodiment, a first adjuster A1, a second adjuster A2, a temperature sensor S, and a control device 90 are added to system 100 according to the first embodiment. In other embodiments, a first adjuster A1, a second adjuster A2, a temperature sensor S, and a control device 90 may be added to system 200 according to the second embodiment or system 300 according to the third embodiment.

[0074] The present disclosure provides ２ It can promote the use of ammonia, which leads to reduced emissions, thereby contributing, for example, to Sustainable Development Goal (SDG) 7: "Ensure access to affordable, reliable, sustainable and modern energy."

[0075] 3 Decomposition device 4 Mixer 6 Third tank 7 Fourth tank 8 Vaporizer 61 Chamber 90 Control device 100 Ammonia decomposition system 200 Ammonia decomposition system 300 Ammonia decomposition system 400 Ammonia decomposition system A1 First adjuster A2 Second adjuster FG0 Flow rate of ammonia flowing through the first line FL0 Flow rate of liquid ammonia flowing through the second line L1 First line L2 Second line R2 Apparent decomposition rate T2 Temperature of mixed gas X1 Gaseous ammonia X2 Liquid ammonia X3 Decomposition gas X4 Mixed gas

Claims

1. An ammonia decomposition system comprising: a first line to which ammonia is supplied; a decomposition device provided in the first line for producing a decomposition gas containing hydrogen from the ammonia; and a second line in fluid communication with the first line at a position downstream of the decomposition device, the second line supplying liquid ammonia to the decomposition gas flowing through the first line to produce a mixed gas.

2. The ammonia decomposition system according to claim 1, further comprising a mixer provided in the first line downstream of the decomposition device for mixing the decomposition gas from the decomposition device and the liquid ammonia from the second line.

3. The ammonia decomposition system of claim 1 or 2, comprising: a tank in fluid communication with the first line and the second line, the tank including a chamber for storing ammonia in two phases including gaseous ammonia and liquid ammonia, the first line connected to an upper portion of the chamber, and the second line connected to a lower portion of the chamber.

4. The ammonia decomposition system according to claim 1 or 2, comprising: a tank in fluid communication with the first line and the second line, the tank supplying liquid ammonia to each of the first line and the second line; and a vaporizer provided in the first line between the tank and the decomposition device, for heating the liquid ammonia flowing through the first line to generate gaseous ammonia.

5. The ammonia decomposition system according to claim 1 or 2, comprising: a first adjuster provided in the first line at a position upstream of the decomposition device and adjusting a flow rate of the ammonia flowing through the first line; a second adjuster provided in the second line and adjusting a flow rate of the liquid ammonia flowing through the second line; and a control device communicatively connected to the first adjuster and the second adjuster, the control device being configured to perform the following: obtaining an apparent decomposition rate of the mixed gas of gaseous ammonia decomposed in the decomposition device; obtaining a temperature of the mixed gas; and controlling the first adjuster and the second adjuster so that the apparent decomposition rate does not fall below a predetermined lower limit value and so that the temperature of the mixed gas does not exceed a predetermined upper limit value.

6. The ammonia decomposition system according to claim 3, comprising: a first adjuster provided in the first line at a position upstream of the decomposition device and adjusting a flow rate of the ammonia flowing through the first line; a second adjuster provided in the second line and adjusting a flow rate of the liquid ammonia flowing through the second line; and a control device communicatively connected to the first adjuster and the second adjuster, the control device being configured to perform the following: obtaining an apparent decomposition rate of the mixed gas of gaseous ammonia decomposed in the decomposition device; obtaining a temperature of the mixed gas; and controlling the first adjuster and the second adjuster so that the apparent decomposition rate does not fall below a predetermined lower limit and so that the temperature of the mixed gas does not exceed a predetermined upper limit.

7. The ammonia decomposition system according to claim 4, comprising: a first adjuster provided in the first line at a position upstream of the decomposition device and adjusting a flow rate of the ammonia flowing through the first line; a second adjuster provided in the second line and adjusting a flow rate of the liquid ammonia flowing through the second line; and a control device communicatively connected to the first adjuster and the second adjuster, the control device being configured to perform the following: obtaining an apparent decomposition rate of the mixed gas of gaseous ammonia decomposed in the decomposition device; obtaining a temperature of the mixed gas; and controlling the first adjuster and the second adjuster so that the apparent decomposition rate does not fall below a predetermined lower limit and so that the temperature of the mixed gas does not exceed a predetermined upper limit.

8. A method for decomposing ammonia, comprising: supplying ammonia to a first line; generating a decomposition gas containing hydrogen from the ammonia by a decomposition device provided in the first line; and supplying liquid ammonia from a second line that is in fluid communication with the first line at a position downstream of the decomposition device to the decomposition gas flowing through the first line, thereby generating a mixed gas.

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