Ammonia reforming device

Abstract

To provide an ammonia reformer that can quickly supply warmed ammonia gas to a reforming device at startup and reduce the amount of ammonia combustion as much as possible during steady operation after startup.SOLUTION: An ammonia reformer includes a first channel section through which ammonia and an oxidizing gas flow, a reforming section 14 containing a combustion catalyst and a reforming catalyst, and a heating section 13 for heating the ammonia and the oxidizing gas. The ammonia reformer includes a heat exchange section 15, which is provided downstream from the reforming section 14, for passing a reforming gas, a second channel section for passing ammonia to the reforming section 14 via the heat exchange section 15, and a control section for controlling an operation of the heating section and flow of ammonia in the first channel section and the second channel section. The control section, at startup, allows ammonia and the oxidizing gas to flow to the first channel section and operates the heating section 13, and during steady operation, causes ammonia to flow to the second channel section, with the ammonia passing through the second channel section being heat exchanged with the reforming gas in the heat exchange section 15.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to an ammonia reforming apparatus.

Background Art

[0002] As a conventional technique of an ammonia reforming apparatus, for example, a hydrogen production catalyst disclosed in Patent Document 1 and a hydrogen production method using the same are known. Patent Document 1 describes a hydrogen production method in which an ammonia combustion catalyst component is arranged in the front stage and an ammonia decomposition catalyst component is arranged in the rear stage with respect to the flow of a gas containing ammonia and oxygen.

[0003] In this type of hydrogen production method, prior to the ammonia decomposition reaction, a predetermined amount of oxygen is added to ammonia to form a reaction gas, and this reaction gas is brought into contact with an ammonia combustion catalyst component to substantially completely consume oxygen by a combustion reaction to obtain combustion heat. Further, the oxygen-free reaction gas whose temperature has been raised by the combustion heat is brought into contact with an ammonia decomposition catalyst component to decompose ammonia in the gas and produce hydrogen. By oxidizing a part of ammonia in this way and efficiently supplying heat required for the decomposition reaction in the reactor, problems caused by partial overheating that easily occur during heat supply from outside the reactor are suppressed, and ammonia is effectively decomposed into hydrogen and nitrogen.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as disclosed in Patent Document 1, when an ammonia combustion catalyst component is arranged in the front stage and an ammonia decomposition catalyst component is arranged in the rear stage with respect to the flow of a gas containing ammonia and oxygen, it is always necessary to raise the temperature to a temperature at which the gas introduced into the reactor can be decomposed. For this reason, since the heat for raising the temperature is the combustion heat of ammonia, there is a problem that the consumption amount of ammonia increases. On the other hand, at the time of starting the ammonia reforming apparatus, it is necessary to promptly supply the heated ammonia to the reformer (reactor).

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide an ammonia reforming apparatus capable of promptly supplying heated ammonia gas to a reformer at the time of startup and reducing the ammonia combustion amount as much as possible during steady operation after startup.

Means for Solving the Problems

[0007] In order to solve the above problems, in an ammonia reforming apparatus having a first flow path portion through which ammonia and an oxidizing gas flow, a reforming portion provided in the first flow path portion and including a combustion catalyst for burning ammonia and a reforming catalyst for reforming ammonia, and a heating portion provided upstream of the reforming portion in the first flow path portion and heating ammonia and an oxidizing gas, a heat exchange portion provided downstream of the reforming portion in the first flow path portion and through which reformed gas from the reforming portion passes, a second flow path portion through which ammonia flows to the heating portion or the reforming portion via the heat exchange portion, and a control portion for controlling the operation of the heating portion and the flow of ammonia in the first flow path portion and the second flow path portion, the control portion, at the time of startup without flowing ammonia through the second flow path portion causes ammonia and an oxidizing gas to flow through the first flow path portion and operates the heating portion, and causes ammonia to flow through the second flow path portion during steady operation after startup, introducing ammonia from the first flow path portion to the reforming portion simultaneously with introducing the ammonia from the second flow path portion to the reforming portion, wherein the ammonia flowing through the second flow path portion is heat-exchanged with the reformed gas in the heat exchange portion.

[0008] In the present invention, the control unit circulates ammonia and an oxidizing gas through the first flow path portion at startup and operates the heating unit. Therefore, ammonia and the oxidizing gas are heated in the heating unit, a part of the ammonia is burned, and a mixed gas of combustion gas and ammonia is introduced into the reforming unit. In the reforming unit, the heated ammonia is reformed by a reforming catalyst. During steady operation when the temperature of the reformed gas stabilizes after startup, the control unit circulates ammonia through the second flow path portion. For this reason, in the heat exchange unit, the reformed gas and the ammonia flowing through the second flow path portion are heat-exchanged, and the ammonia is heated. The heated ammonia is introduced into the reforming unit and reformed by a reforming catalyst. That is, at startup, in order to prioritize the temperature rise of the reforming unit, the ammonia gas heated by operating the heating unit can be quickly supplied to the reforming unit, and the combustion of ammonia can be suppressed during steady operation, so the consumption amount due to the combustion of ammonia can be suppressed.

[0009] Further, in the above ammonia reforming apparatus, the combustion catalyst and the reforming catalyst in the reforming unit may be mixed. In this case, since the combustion catalyst and the reforming catalyst in the reforming unit are mixed, in the reforming unit, a part of the ammonia is burned, and the heat of combustion in the reforming unit can be used for reforming ammonia. Therefore, ammonia can be reformed in the reforming unit even if the heating unit is not operated.

[0010] Further, in the above ammonia reforming apparatus, the control unit may be configured to operate the heating unit when the temperature of the reformed gas obtained in the reforming unit becomes equal to or lower than a threshold value after stopping the supply of ammonia to the heating unit via the first flow path portion. In this case, the ammonia flowing through the second flow path portion is introduced into the reforming unit and reformed by a reforming catalyst. However, when the temperature of the reformed gas exiting the reforming unit becomes equal to or lower than the threshold value, the heating unit is operated. Therefore, the heated air from the first flow path can heat the ammonia in the reforming unit.

[0011] In addition, in the ammonia reforming apparatus described above, the second flow path portion may be configured to be connected so as to flow into the reforming portion via the heat exchange portion and the heating portion.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide an ammonia reforming apparatus capable of promptly supplying heated ammonia gas to a reformer at startup and reducing the ammonia combustion amount as much as possible during steady operation after startup.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0014] (First Embodiment) Hereinafter, an ammonia reforming apparatus according to a first embodiment will be described with reference to the drawings. As shown in FIG. 1, the ammonia reforming apparatus 10 of the present embodiment includes an air supply unit 11, an ammonia supply unit 12, a heating unit 13, a reforming unit 14, and a heat exchange unit 15. The ammonia reforming apparatus 10 includes a flow path 16 connecting the air supply unit 11 and the heating unit 13, a flow path 17 connecting the ammonia supply unit 12 and the flow path 16, a flow path 18 connecting the heating unit 13 and the reforming unit 14, and a flow path 19 connecting the reforming unit 14 and the heat exchange unit 15. The flow paths 16 to 18 constitute a first flow path portion through which ammonia flows through the heating unit 13, the reforming unit 14, and the heat exchange unit 15.

[0015] The air supply unit 11 has a function of supplying air, which is an oxidizing gas, to the heating unit 13, and is, for example, a blower. The air supply unit 11 has a function of changing the supply amount of the air supplied to the heating unit 13. The ammonia supply unit 12 has a function of supplying ammonia gas. The ammonia supply unit 12 has an ammonia tank (not shown) for storing ammonia in a liquid state and a vaporizer (not shown) for vaporizing liquid ammonia to generate ammonia gas. The ammonia of the ammonia supply unit 12 is injected into the flow path 16 through the flow path 17, and is mixed with air in the flow path 16 to become a mixed gas of ammonia and air. The mixed gas is introduced into the heating unit 13 through the flow path 16.

[0016] The heating unit 13 has a function of heating the mixed gas of ammonia and air introduced through the flow path 16, and is, for example, an electric heater. The heating unit 13 raises the temperature of the ammonia mixed gas, burns a part of the ammonia, and raises the temperature to near a temperature suitable for the reforming of ammonia. Specifically, the heating unit 13 burns ammonia gas in a temperature range of about 200°C to 400°C. The heating gas containing the combustion gas of ammonia generated in the heating unit 13 is introduced into the reforming unit 14. The heating unit 13 is connected to the controller 20, and controls the heating of the mixed gas in the heating unit 13.

[0017] The controller 20 corresponds to a control unit and includes, although not shown, a CPU and a storage unit composed of a RAM, a ROM, etc. The controller 20 may be provided with dedicated hardware for executing at least a part of various processes, for example, an application specific integrated circuit (ASIC). Various programs for controlling the ammonia reforming apparatus 10 are stored in the controller 20. The controller 20 controls the air supply unit 11, the ammonia supply unit 12, and the heating unit 13.

[0018] The reforming unit 14 has a function of reforming the mixed gas heated in the heating unit 13. Specifically, the reforming unit 14 includes a honeycomb carrier (not shown) made of porous ceramics and an ATR catalyst (not shown) supported on the honeycomb carrier. The honeycomb carrier is, for example, a honeycomb structure made of porous ceramics such as cordierite, mullite, and silicon nitride. The honeycomb carrier can be obtained by extruding a ceramic material mixed with water and a binder using an extrusion molding machine, cutting the extruded body, drying it, and firing it after drying.

[0019] The ATR catalyst is a catalyst for reforming ammonia in an autothermal reformer (ATR). The ATR catalyst is a catalyst that reforms ammonia by burning ammonia and decomposing ammonia into hydrogen by the combustion heat of ammonia.

[0020] The ATR catalyst burns ammonia gas in a temperature range of about 200°C to 400°C, for example, and reforms ammonia gas in a temperature range higher than the combustion temperature of ammonia gas (for example, about 250°C to 500°C). The ATR catalyst includes a combustion catalyst that burns ammonia gas and a reforming catalyst that reforms ammonia gas into hydrogen. As the catalyst metal of the combustion catalyst, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt can be used. Also, as the catalyst metal of the reforming catalyst, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt can be used.

[0021] The ATR catalyst in the reforming unit 14 is a mixed catalyst in which a combustion catalyst that burns ammonia and a reforming catalyst that reforms ammonia into hydrogen are mixed. Let the combustion reaction rate (r A ) of ammonia by the combustion catalyst and the reforming reaction rate (r D ) of ammonia by the reforming catalyst. Then, the ATR catalyst of this embodiment has a reaction rate ratio (r A / r D) is less than 1, the combustion catalyst and the reforming catalyst are mixed. That is, the ATR catalyst is a reforming-dominant mixed catalyst in which the reforming reaction rate (r D ) is greater than the combustion reaction rate (r A ). Further, the ATR catalyst is such that the combustion catalyst and the reforming catalyst are mixed so that the reaction rate ratio between the combustion reaction rate of ammonia by the combustion catalyst and the reforming reaction rate of ammonia by the reforming catalyst is less than the threshold value (1.0). In the reforming-dominant ATR catalyst, the reforming of ammonia by the reforming catalyst wins over the combustion of ammonia by the combustion catalyst and reacts. Note that the ATR catalyst with a reaction rate ratio (r A / r D ) of 1 or more is a combustion-dominant mixed catalyst, and the combustion of ammonia by the combustion catalyst wins over the reforming of ammonia by the reforming catalyst and reacts.

[0022] In the present embodiment, a heat exchange unit 15 connected to the reforming unit 14 by a flow path 19 is provided downstream of the reforming unit 14. The heat exchange unit 15 has a function of performing heat exchange between the reformed gas obtained by reforming ammonia in the reforming unit 14 and ammonia introduced into the heat exchange unit 15 from the ammonia supply unit 12 without passing through the heating unit 13 and the reforming unit 14. The heat exchange unit 15 has a reformed gas flow path unit 21 through which the reformed gas passes and an ammonia flow path unit 22 through which ammonia passes. The inlet of the reformed gas flow path unit 21 is connected to the flow path 19, and the outlet of the reformed gas flow path unit 21 is connected to a flow path 24 that connects the reformed gas utilization device 23 provided on the downstream side of the ammonia reforming device 10 and the heat exchange unit 15. The ammonia flow path unit 22 in the heat exchange unit 15 is formed so that the flow path becomes as long as possible in the heat exchange unit 15. The reason is to secure the surface area for efficient heat exchange. Therefore, the second flow path unit is longer than the first flow path unit.

[0023] The reformed gas utilization device 23 is a device that uses the reformed gas reformed by the ammonia reforming device 10. The reformed gas utilization device 23 is, for example, an ammonia engine that uses hydrogen reformed from ammonia as fuel, and may be a fuel cell or the like in addition to the ammonia engine.

[0024] Incidentally, the ammonia reforming apparatus 10 includes a flow path 25 that connects the flow path 17 and the heat exchange unit 15. The flow path 25 is a flow path branched from the flow path 17, and the flow path 25 is connected to the inlet of the ammonia flow path portion 22 of the heat exchange unit 15. A flow rate control valve 26 is provided at the branch portion in the flow path 17. The flow rate control valve 26 is an electromagnetic valve that can adjust the flow rate of ammonia passing from the flow path 17 to the flow path 16 and the flow rate of ammonia passing from the flow path 17 to the flow path 25 according to a command from the controller 20. The flow rate control valve 26 adjusts the flow rate ratio of ammonia to the flow paths 16 and 25, and also functions as a flow path switching valve, for example, by not flowing ammonia through the flow path 25 and only flowing ammonia through the flow path 17.

[0025] The ammonia reforming apparatus 10 includes a flow path 27 that connects the outlet of the ammonia flow path portion 22 of the heat exchange unit 15 and the reforming unit 14. The flow path 27 is a flow path for introducing ammonia flowing through the heat exchange unit 15 into the reforming unit 14. The ammonia introduced into the reforming unit 14 through the flow path 27 is reformed in the reforming unit 14, and the reformed gas is introduced into the heat exchange unit 15 through the flow path 19. A part of the flow path 17, the flow path 25, and the flow path 27 constitute a second flow path for flowing ammonia through the heat exchange unit 15 to the reforming unit 14.

[0026] In the heat exchange unit 15, when the reformed gas passes through the reformed gas flow path portion 21 through the flow path 19 and ammonia passes through the ammonia flow path portion 22, heat exchange occurs between the reformed gas in the reformed gas flow path portion 21 and the ammonia in the ammonia flow path portion 22. In the heat exchange unit 15, the high-temperature reformed gas is cooled by the low-temperature ammonia, and the ammonia is heated by the reformed gas. A temperature sensor 28 for detecting the temperature of the reformed gas immediately after being led out from the reforming unit 14 is provided in the flow path 19. The temperature of the reformed gas detected by the temperature sensor 28 is transmitted to the controller 20.

[0027] In the ammonia reforming apparatus 10 of the present embodiment, the controller 20 controls each part according to the operation at startup and the steady operation after startup. As shown in FIG. 2, in the operation at startup, the controller 20 operates the heating unit 13, supplies sufficient air from the air supply unit 11 to the heating unit 13, and controls the flow rate control valve 26 so as to inject ammonia into the flow path 16 through the flow path 17.

[0028] The controller 20 monitors the temperature of the reformed gas derived from the reforming unit 14 detected by the temperature sensor 28, and stops the heating unit 13 at the timing X1 when the detected temperature is equal to or higher than the first threshold value (for example, 200°C) T1. When the temperature of the reformed gas is equal to or higher than the first threshold value T1, it is the temperature at which ammonia burns. In the reforming unit 14, ammonia burns by the combustion catalyst, and further, since the temperature of the reforming unit 14 rises, it is no longer necessary to operate the heating unit 13.

[0029] Next, when the temperature detected from the temperature sensor 28 is equal to or higher than the second threshold value (for example, 600°C) T2 at the timing X2, the controller 20 determines that it is in steady operation, controls the flow rate control valve 26 to introduce ammonia into the flow paths 17 and 25, and reduces the air supply amount from the air supply unit 11. As shown in FIG. 2, when the temperature of the reformed gas is equal to or higher than the second threshold value T2, the temperature in the reforming unit 14 is the temperature required for reforming to generate hydrogen from ammonia, and ammonia is reformed in the reforming unit 14. Further, the temperature of the reforming unit 14 is maintained by the combustion of ammonia in the reforming unit 14. In FIG. 2, the period from the start of startup to the timing X2 including the timing X1 is the startup period P of the operation at startup, and the period after the timing X2 is the period of steady operation.

[0030] Next, the operation of the ammonia reforming apparatus 10 of the present embodiment will be described. When the ammonia reforming apparatus 10 is started up, the air supply unit 11 continuously introduces air into the flow path 16, and the flow rate control valve 26 switches the flow path so that ammonia is continuously injected into the flow path 16 through the flow path 17. Therefore, at startup, ammonia does not flow through the flow path 25. In the flow path 17, ammonia is mixed with air, and the mixed gas of ammonia and air is introduced into the heating unit 13. The heating unit 13 is operating, and the mixed gas is heated by the heating unit 13. It is desirable that the mixed gas be heated to the combustion temperature of ammonia as quickly as possible in the heating unit 13. When the temperature of the mixed gas is heated to the combustion temperature of ammonia, a part of the ammonia burns.

[0031] The heated mixed gas is continuously introduced into the reforming unit 14. However, since a part of the ammonia is burning, the temperature of the reforming unit 14 rises. The mixed gas whose temperature has risen in the reforming unit 14 is led out to the flow path 19. When the temperature of the mixed gas led out from the reforming unit 14 becomes equal to or higher than the first threshold value T1, since the temperature of the reforming unit 14 has risen to the temperature required for the combustion of ammonia, the controller 20 stops the operation of the heating unit 13. At this time, only the combustion of ammonia is carried out in the reforming unit 14, and the reforming of ammonia is not carried out.

[0032] Even if the operation of the heating unit 13 is stopped and the heating unit 13 does not heat the mixed gas, air is introduced into the reforming unit 14 through the flow paths 16 and 18, and a part of the ammonia burns in the reforming unit 14. Therefore, the temperature rise of the reforming unit 14 continues. When the temperature of the gas led out from the reforming unit 14 becomes equal to or higher than the second threshold value T2, since ammonia has started to be reformed in the reforming unit 14, the controller 20 determines that it is in the steady operation after startup. For this reason, the flow rate control valve 26 switches the flow path so that the ammonia from the ammonia supply unit 12 is introduced from the flow path 17 to the flow path 25. By switching the flow path of the flow rate control valve 26, ammonia is not injected into the flow path 16, but the air from the air supply unit 11 is introduced into the flow path 16. The amount of air after the flow path switching is less than the amount of air before the flow path switching. The reason for reducing the amount of air during steady operation is to suppress the amount of ammonia consumed by combustion.

[0033] In steady operation, ammonia is reformed using the heat of combustion in the reforming section 14, but the reformed gas introduced from the reforming section 14 into the flow path 19 is still at a high temperature. The reformed gas passes through the flow path 19 and is introduced into the heat exchange section 15, and the reformed gas passes through the reformed gas flow path section 21. On the other hand, ammonia is introduced into the heat exchange section 15 through the flow path 25 and passes through the ammonia flow path section 22. In the heat exchange section 15, heat exchange is performed between the high-temperature reformed gas and the low-temperature ammonia. That is, in the heat exchange section 15, the reformed gas is cooled and the ammonia is heated. When the ammonia passing through the heat exchange section 15 is heated to, for example, the first threshold value T1, the combustion of ammonia becomes possible. For this reason, when ammonia is introduced from the heat exchange section 15 into the reforming section 14 through the flow path 27, a part of the ammonia is burned by the air introduced from the flow path 18, and the heat of combustion of ammonia is used for the reforming of ammonia that is not burned in the reforming section 14.

[0034] The reformed gas cooled in the heat exchange section 15 is introduced into the reformed gas utilization device 23 through the flow path 24. Since the reformed gas is cooled in the heat exchange section 15, it is easy to use in the reformed gas utilization device 23. The reformed gas introduced from the reforming section 14 into the flow path 19 is mainly hydrogen gas reformed from ammonia, but contains a small amount of un-reformed ammonia gas in addition to air.

[0035] By the way, in FIG. 2, when the ammonia reforming device 10 is in steady operation, only ammonia passing through the flow paths 25 and 27 is introduced into the reforming section 14, but the temperature of the reforming section 14 may decrease for some reason such as load fluctuations of the reformed gas utilization device 23. In this case, for example, as shown in FIG. 3, the heating section 13 may be operated again and ammonia may be introduced into the heating section 13.

[0036] In FIG. 3, when the temperature detected by the temperature sensor 28 reaches a timing X3 at which the temperature is equal to or lower than a third threshold value T3 as a threshold value, the controller 20 activates the heating unit 13, controls the flow rate control valve 26, and introduces ammonia from the ammonia supply unit 12 into the flow path 16. The flow rate of ammonia introduced into the flow path 16 is set to the flow rate of ammonia (B1) at startup. Then, the controller 20 reduces the flow rate of ammonia introduced into the flow path 25 by an amount (C1 - C2) corresponding to the flow rate of ammonia (B1) introduced into the flow path 16. Further, the controller 20 controls the air supply unit 11 to increase the air supply amount (D2) during steady operation to the air supply amount (D1) at startup.

[0037] Therefore, even if the temperature of the reformed gas decreases, ammonia is introduced into the heating unit 13 and heated by the heating unit 13, so that the reforming unit 14 is heated up. As a result, the temperature of the reformed gas from the reforming unit 14 passing through the flow path 19 rises and becomes equal to or higher than the second threshold value T2. As shown in FIG. 3, at a timing X4 when the temperature of the reformed gas becomes equal to or higher than the second threshold value T2, the introduction of ammonia into the flow path 16 is stopped and the operation of the heating unit 13 is stopped. Further, the air supply amount to the flow path 16 is reduced. In FIG. 3, the period between the timings X3 and X4 is a reheating period Q for the reheating operation during steady operation, and the period excluding the startup period P and the reheating period Q is a steady operation period without heating by the heating unit 13.

[0038] The ammonia reforming apparatus 10 according to the present embodiment has the following effects. (1) When the controller 20 operates, ammonia is circulated through the first flow path portion at startup to activate the heating unit 13. Thus, the ammonia is heated in the heating unit 13, and part of the ammonia is burned, and a mixed gas of combustion gas and ammonia is introduced into the reforming unit 14. In the reforming unit 14, the heated ammonia is reformed by a reforming catalyst. During steady operation when the temperature of the reformed gas stabilizes after startup, the controller 20 circulates ammonia through the second flow path portion and stops the circulation of ammonia in the first flow path portion, and circulates air through the first flow path portion. Therefore, in the heat exchange unit 15, the reformed gas from the reforming unit 14 and the ammonia flowing through the second flow path portion are heat-exchanged, and the ammonia is heated. The heated ammonia is introduced into the reforming unit 14 and reformed by a reforming catalyst. That is, at startup, in order to prioritize the temperature rise of the reforming unit 14, the ammonia gas heated by the operation of the heating unit 13 can be quickly supplied to the reforming unit 14, and during steady operation, the operation of the heating unit 13 is stopped to suppress the consumption amount of ammonia due to the combustion of ammonia, and the combustion of ammonia can be suppressed.

[0039] (2) Since the combustion catalyst and the reforming catalyst in the reforming unit 14 are mixed, in the reforming unit 14, part of the ammonia is burned, and the combustion heat in the reforming unit 14 can be used for the reforming of ammonia. Note that the ATR catalyst in the reforming unit 14 is a reforming-predominant mixed catalyst in which the reforming reaction rate (r D ) is greater than the combustion reaction rate (r A ). Therefore, the amount of ammonia consumed by combustion in the reforming unit 14 is suppressed, and the amount of ammonia consumed by reforming can be relatively increased.

[0040] (3) The ammonia flowing through the second flow path portion is introduced into the reforming unit 14 and reformed by a reforming catalyst. When the temperature of the reformed gas exiting the reforming unit 14 becomes equal to or lower than the third threshold value T3, the heating unit 13 is operated and ammonia is introduced into the heating unit 13. Therefore, the heated mixed gas from the flow path 16, which is the first flow path portion, can raise the temperature of the ammonia in the reforming unit 14. That is, even when the temperature of the reformed gas decreases during steady operation, ammonia is introduced into the heating unit 13 and heated in the heating unit 13, so that the temperature of the reforming unit 14 can be raised.

[0041] (4) Since the flow control valve 26 is provided, even if the temperature of the reformed gas decreases during steady operation, ammonia can be introduced into the second flow path while ammonia can be introduced into the heating unit 13. Further, the flow control valve 26 can function as a flow path switching valve.

[0042] (5) Although the flow paths 25 and 27 of the second flow path section are likely to be longer than the flow paths 16 and 18 of the first flow path section, the ammonia flowing through the flow path 25 is heated by heat exchange with the reformed gas in the heat exchange unit 15. Therefore, the heated ammonia can be introduced into the reforming unit 14 through the flow path 27. Since the first flow path section is shorter than the second flow path section, the heated ammonia can be quickly supplied to the reforming unit 14. Also, although it takes time for the temperature to reach the first threshold value T1 only by the heat generated by ammonia combustion, the time for temperature rise can be shortened by heating the ammonia by the heating unit 13.

[0043] (Second Embodiment) Next, the ammonia reforming apparatus according to the second embodiment will be described. This embodiment is different from the first embodiment in that the second flow path section is connected to the heating unit instead of the reforming unit. In this embodiment, for the same configuration as the first embodiment, the description of the first embodiment is incorporated and common reference numerals are used.

[0044] As shown in FIG. 4, the ammonia reforming apparatus 30 of this embodiment includes a flow path 31 that connects the outlet of the ammonia flow path section 22 of the heat exchange unit 15 and the heating unit 13. A part of the flow path 17, the flow path 25, and the flow path 31 constitute a second flow path through which ammonia flows to the heating unit together with the heat exchange unit 15. That is, the second flow path section is connected so as to flow to the heating unit via the heat exchange unit 15 and the heating unit 13. Therefore, during steady operation, the ammonia heated in the heat exchange unit 15 passes through the heating unit 13, is mixed with air in the heating unit 13, and is introduced into the reforming unit 14.

[0045] In this embodiment, when ammonia passes through the heating unit 13 during steady operation, if the temperature of the reformed gas exiting the reforming unit 14 is lower than the third threshold value T3, the controller 20 activates the heating unit 13 even during steady operation. By heating the ammonia gas with the heating unit 13, the heat required for reforming is ensured in the reforming unit 14. When the temperature of the reformed gas is equal to or higher than the third threshold value T3, it is not necessary to activate the heating unit 13.

[0046] In this embodiment, the ammonia flowing through the flow path 25 during steady operation flows into the reforming unit 14 via the heat exchange unit 15 and the heating unit 13, so the ammonia can be heated by the heating unit 13 as needed.

[0047] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the invention. For example, the following modifications may be made.

[0048] ○ In the above embodiment, the combustion catalyst and the reforming catalyst in the reforming unit are an ATR catalyst in which they are mixed, but the present invention is not limited to this. The combustion catalyst and the reforming catalyst do not have to be mixed in the reforming unit. Further, the reforming unit may include a reforming catalyst and may not include a combustion catalyst. ○ In the above embodiment, the heating unit is an electric heater, but the heating unit is not limited to an electric heater. For example, the heating unit may use an electrically heated catalyst (EHC) in which an electric heater and a combustion catalyst are integrally configured. ○ In the above embodiment, during steady operation, ammonia is not introduced from the first flow path portion into the reforming unit at the same time as the introduction of ammonia from the second flow path into the reforming unit, but the present invention is not limited to this. During steady operation, ammonia may be introduced from the first flow path portion into the reforming unit at the same time as the introduction of ammonia from the second flow path into the reforming unit. portion from the second flow path into the reforming unit, but this is not the only case. During steady operation, ammonia may be introduced from the first flow path portion into the reforming unit at the same time as the introduction of ammonia from the second flow path into the reforming unit. portion from the second flow path into the reforming unit, but this is not the only case. During steady operation, ammonia may be introduced from the first flow path portion into the reforming unit at the same time as the introduction of ammonia from the second flow path into the reforming unit. ○ In the above embodiment, the ammonia reforming device and the reformed gas utilization device are simply connected by a flow path, but this is not the limit. For example, a cooler using a coolant may be interposed between the ammonia reforming device and the reformed gas utilization device, and the reformed gas may be cooled by the cooler. In this case, since the reformed gas is further cooled, it becomes easier to use the reformed gas in the reformed gas utilization device. ○ In the above embodiment, the temperature sensor is provided in the flow path, but it is not limited to this. The temperature sensor may be, for example, a temperature sensor that detects the temperature of the reforming section. ○ In the above embodiment, a second flow path section branched from the first flow path section through which air flows from the ammonia supply section is provided, and a flow rate control valve is provided at the branch section to adjust the ammonia flow rate in the first flow path section and the second flow path section, and to switch the ammonia flow path. However, this is not the only way. For example, on-off valves may be provided in the first flow path section and the second flow path section respectively, and the ammonia flow paths in the first flow path section and the second flow path section may be simply switched. ○ In the above embodiment, the controller switches the ammonia flow path based on the temperature of the reformed gas, but it is not limited to this. The start-up time from the start-up until the steady operation when the temperature of the reformed gas becomes equal to or higher than the second threshold value is grasped and set in advance, and the timer function of the controller is used to switch the ammonia flow path at the timing when the time has passed the preset start-up time.

Explanation of Reference Numerals

[0049] 10, 30 Ammonia reforming device 11 Air supply section 12 Ammonia supply section 13 Heating section 14 Reforming section 15 Heat exchange section 16, 17, 18, 19, 24, 25, 27, 31 Flow path 20 Controller 21 Reformed gas flow path section 22 Ammonia flow path section 23 Reformed gas utilization device 26 Flow path switching valve 28 Temperature sensor 30 Ammonia reformer B1, C1, C2 Ammonia flow rate D1, D2 Air volume P Startup period Q Reheating period T1 First threshold value T2 Second threshold value X1, X2 Timing

Claims

1. a first flow path section through which ammonia and an oxidizing gas flow; a reforming section provided in the first flow path section and including a combustion catalyst for burning ammonia and a reforming catalyst for reforming ammonia; a heating section provided upstream of the reforming section in the first flow path section for heating ammonia and an oxidizing gas, in an ammonia reforming apparatus having: a heat exchange section provided downstream of the reforming section in the first flow path section through which reformed gas from the reforming section passes; a second flow path section through which ammonia flows to the heating section or the reforming section via the heat exchange section; a control section for controlling the operation of the heating section and the flow of ammonia in the first flow path section and the second flow path section, having: the control section is configured to: during startup, circulate ammonia and an oxidizing gas through the first flow path section without flowing ammonia through the second flow path section and operate the heating section; during steady operation after startup, circulate ammonia through the second flow path section, introduce ammonia from the second flow path section into the reforming section simultaneously with introducing ammonia from the first flow path section into the reforming section; the ammonia passing through the second flow path section is heat-exchanged with reformed gas in the heat exchange section, characterized in that the ammonia reforming apparatus.

2. The ammonia reforming apparatus according to claim 1, characterized in that the combustion catalyst and the reforming catalyst in the reforming section are mixed.

3. The ammonia reforming apparatus according to claim 1 or 2, characterized in that the control section operates the heating section when the temperature of the reformed gas obtained in the reforming section becomes equal to or lower than a threshold value after stopping the supply of ammonia to the heating section through the first flow path section.

4. The ammonia reforming apparatus according to any one of claims 1 to 3, characterized in that the second flow path section is connected to flow to the reforming section via the heat exchange section and the heating section.

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