Ammonia reformer and method of operating the ammonia reformer

Abstract

To provide an ammonia reforming apparatus capable of stably supplying heat required for decomposing ammonia to an ammonia reforming catalyst, and to provide an operating method of the ammonia reforming apparatus.SOLUTION: A reforming apparatus for decomposing ammonia to generate hydrogen comprises a first catalytic reactor, a combustor, a first feed line, and a second feed line. The first catalytic reactor generates a first gas containing at least hydrogen from ammonia. The first feed line is connected to a downstream side of the first catalytic reactor. The second supply line is branched from the first supply line and connected to the combustor. The combustor burns a part or all of the first gas supplied through the second supply line.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an ammonia reforming apparatus and a method for operating the ammonia reforming apparatus.

Background Art

[0002] In recent trends towards carbon neutrality, carbon-free energy sources such as hydrogen and ammonia have attracted attention as alternative fuels to conventional fossil fuels Among them, ammonia is regarded as a promising fuel for internal combustion engines, external combustion engines, boilers, etc., due to its high volumetric energy density and ease of storage and transportation

[0003] When ammonia is used as a fuel for internal combustion engines, external combustion engines, boilers, etc., since the ignition property and flame propagation speed of ammonia are inferior to those of fossil fuels conventionally used, it is known that stable combustion can be achieved by decomposing a part of the fuel ammonia into a reformed gas composed of hydrogen, nitrogen, and ammonia

[0004] Although ammonia can be efficiently decomposed by a catalytic reaction, since the reaction temperature of the catalyst is generally in a high temperature range of 200 degrees or more, it is necessary to supply heat to an ammonia reforming catalyst that decomposes ammonia

[0005] In Patent Document 1, a solid oxide fuel cell system including first heating means for heating an ammonia decomposition section is disclosed

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the solid oxide fuel cell system described in Patent Document 1 obtains the heat necessary for ammonia reforming by the spontaneous combustion of ammonia in the combustion exhaust gas discharged from the power generation module. If an internal combustion engine, gas turbine, boiler, or the like, which has almost no combustible components in its combustion exhaust gas, is used as a downstream engine, it is not possible to secure the heat necessary for ammonia reforming.

[0008] In view of the above circumstances, the present invention aims to provide an ammonia reforming apparatus and a method for operating an ammonia reforming apparatus that can stably supply the heat necessary for the decomposition of ammonia to the ammonia reforming catalyst, regardless of the type of downstream engine that is the end user of the reformed gas. [Means for solving the problem]

[0009] A first aspect of the present invention is a reforming apparatus for decomposing ammonia to generate hydrogen, The reforming apparatus comprises a first catalytic reactor having a first catalyst layer, a combustor, a first supply line, and a second supply line. An induction heating heater and a second catalytic reactor having a second catalytic layer which is a metal honeycomb structure, Equipped with, The first catalytic reactor generates a first gas containing at least hydrogen from ammonia, The first supply line is connected to the downstream side of the first catalytic reactor, The second supply line branches off from the first supply line and is connected to the combustor. The induction heater heats the second catalytic reactor, The second catalytic reactor generates a second gas containing at least hydrogen from ammonia. The combustor controls part or all of the first gas supplied via the second supply line. , and the second gas Burn it, The first catalyst layer and the second catalyst layer contain at least one metal selected from nickel, ruthenium, cobalt, iron, palladium, platinum, gold, silver, and copper. The volume of the second catalytic reactor is 15% or less of the volume of the first catalytic reactor. Ammonia reforming plant.

[0010] Furthermore, a second aspect of the present invention is the method for operating the ammonia reforming apparatus described in claim 1, The aforementioned operating method comprises a first catalytic reaction step, a combustion step, a heating step, an electric heating step, and a second catalytic reaction step. The first catalytic reaction step generates a first gas containing at least hydrogen from ammonia, In the electric heating step, the induction heating The temperature of the second catalytic reactor is raised by the heater, The second catalytic reaction step generates a second gas containing at least hydrogen from ammonia, In the combustion step, a part or all of the first gas and the second gas are combusted, The temperature raising step is a method of operating an ammonia reforming apparatus that raises the temperature of the first catalytic reactor with the combustion heat generated in the combustion step.

[0011] According to the ammonia reforming apparatus and the method of operating an ammonia reforming apparatus of the present invention, it is possible to provide an ammonia reforming apparatus and a method of operating an ammonia reforming apparatus that can stably supply heat regardless of the type of the subsequent stage apparatus that is the destination of the reformed gas to the ammonia reforming catalyst.

Brief Description of Drawings

[0012] [Figure 1] Overall view of ammonia reforming apparatus 1 [Figure 2] Configuration diagram A of ammonia reforming apparatus 1 [Figure 3] Configuration diagram B of ammonia reforming apparatus 1 [Figure 4] Configuration diagram C of ammonia reforming apparatus 1 [Figure 5] Configuration diagram of ammonia reforming apparatus 2 [Figure 6] It shows the operation of the flowchart of the first embodiment. [Figure 7] It shows the operation of the flowchart of the second embodiment.

Modes for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Various characteristic matters shown in the embodiments described below can be combined with each other.

[0014] Figure 1 is a diagram showing an overall view of the ammonia reforming apparatus 1. The ammonia reforming apparatus 1 mainly includes a first catalytic reactor 11, a combustor 12, a first supply line 13, and a second supply line 14. The ammonia gas supplied to the first catalytic reactor 11 is decomposed into a reformed gas containing hydrogen and nitrogen at a predetermined reaction rate in the first catalytic reactor 11. The generated reformed gas containing at least hydrogen is delivered to the subsequent stage through the first supply line 13, and part or all of the reformed gas is supplied to the combustor 12 through the second supply line 14. In the combustor 12, the heat generated using the supplied reformed gas as fuel is supplied to the first catalytic reactor 11 and serves as a heat source required for the decomposition reaction of the ammonia gas.

[0015] The first catalytic reactor 11 mainly includes a catalyst layer and a reaction vessel for storing the catalyst layer. The catalyst layer is preferably one containing at least one metal selected from nickel, ruthenium, cobalt, iron, palladium, platinum, gold, silver, and copper, but is not limited thereto. Also, from the viewpoint of corrosion resistance, the reaction vessel is preferably made of stainless steel, but is not limited thereto.

[0016] When ammonia gas flows into the first catalytic reactor 11 maintained in a predetermined temperature range, hydrogen and nitrogen are generated from ammonia according to the reaction formula shown in Equation (1). NH3 → 3 / 2H2 + 1 / 2N2 ···(1) At this time, the temperature range of the first catalytic reactor 11 is preferably from 200 degrees to 700 degrees, more preferably from 300 degrees to 700 degrees.

[0017] The combustor 12 mainly includes a burner, and may further include a flow rate valve, an ignition device, and a blower.

[0018] The first supply line 13 forms a flow path that supplies the reformed gas produced in the first catalytic reactor 11 to downstream customers. The reformed gas supplied via the first supply line 13 is supplied to internal combustion engines such as diesel engines and gas engines, boilers and external combustion engines, but the customers are not limited to these and may include fuel cells, for example.

[0019] The second supply line 14 branches off from the first supply line 13 and forms a flow path that supplies some or all of the reformed gas produced in the first catalytic reactor 11 to the combustor. The reformed gas supplied to the combustor 12 via the second supply line 14 is burned by the burner in the combustor 12, and the heat generated is supplied to the first catalytic reactor 11.

[0020] <First Embodiment> Figure 1 shows an overall view of the ammonia reformer 1, which is one aspect of this embodiment. The configuration diagram of the ammonia reformer 1 when the ammonia tank 31 that stores the ammonia to be reformed as liquefied ammonia, the heat exchanger 32 installed between the ammonia tank 31 and the ammonia reformer 1, and the gas engine 41 installed downstream of the ammonia reformer 2 are shown in Figure 2.

[0021] The liquefied ammonia stored in the ammonia tank 31 is heated via the heat exchanger 32, vaporized into ammonia gas, and the ammonia gas is supplied to the first catalytic reactor 11 after its flow rate is adjusted by the valve 51. At this time, the heat from the combustion exhaust gas of the gas engine 41 connected downstream of the first catalytic reactor 11 can be used as the heat source for the heat exchanger 32. Subsequently, the ammonia gas decomposition reaction shown in equation (1) occurs in the first catalytic reactor 11, and some or all of the resulting reformed gas is supplied to the combustor 12. The heat generated by the combustion of the reformed gas in the combustor 12 is supplied to the first catalytic reactor 11.

[0022] Here, unburned residual oxygen contained in the combustion exhaust gas of the gas engine 41 connected downstream of the first catalytic reactor 11 can be used as the oxidizer in the combustor 12. The combustion exhaust gas of the gas engine 41 is supplied to the combustor 12 after its flow rate is adjusted by the valve 53. Since the sensible heat of the combustion exhaust gas can be used as part of the heat supplied to the first catalytic reactor 11, it is possible to reduce the amount of reformed gas used as combustion fuel in the combustor 12.

[0023] Figure 3 shows a modified example of this embodiment. If the residual oxygen concentration in the combustion exhaust gas of the gas engine 41 is insufficient, air can be used as the oxidizer in the combustor 12. Preferably, the air used as the oxidizer is heated using the heat from the combustion exhaust gas of the gas engine 41 as a heat source, passed through the heat exchanger 33, and then supplied to the combustor 12 after its flow rate is adjusted by the valve 53.

[0024] Figure 4 shows another modified example of this embodiment. As shown in Figure 4, the liquefied ammonia stored in the ammonia tank 31 may be heated via a heat exchanger 34 located between the first catalytic reactor 11 and the valve 52, and vaporized into ammonia gas. In this case, it is preferable to use the heat of the reformed gas produced in the first catalytic reactor 11 as the heat source used in the heat exchanger 34.

[0025] As mentioned above, if an internal combustion engine, gas turbine, boiler, or other device with almost no combustible components in its combustion exhaust gas is used as a downstream engine in an ammonia reforming system, it will not be possible to stably secure the heat necessary for ammonia reforming.

[0026] Therefore, an ammonia reforming apparatus 1 is conceivable that utilizes part or all of the reformed gas supplied to the customer as fuel to secure the heat source necessary for ammonia decomposition. By utilizing part or all of the reformed gas obtained by the decomposition of ammonia gas as fuel for the combustor, it becomes possible to stably burn it in the combustor 12 and stably secure the heat source for the ammonia reforming apparatus 1.

[0027] Here, the reformed gas of ammonia, hydrogen, and nitrogen, obtained by decomposing a portion of the ammonia gas into hydrogen and nitrogen, is generally known to have better flammability than ammonia gas, and as mentioned above, contributes to the stable combustion of the combustor 12. The reaction rate of ammonia gas in the first catalytic reactor 11 is preferably 5% to 70%, but more preferably 30% to 60% when the downstream engine is an internal combustion engine, gas turbine, boiler, etc.

[0028] Figure 6 is a flowchart showing the operation of the ammonia reformer 1 during steady-state operation. The following explanation will follow the flow shown in this flowchart.

[0029] When ammonia gas is supplied to the first catalytic reactor 11, a decomposition reaction of ammonia occurs in the first catalytic reactor 11 (step S101), producing a reformed gas of ammonia, hydrogen, and nitrogen. Part or all of the generated reformed gas is supplied to the combustor 12 via the second supply line 14 and combusted in the combustor 12 (step S102). The heat generated by the combustion is supplied to the first catalytic reactor 11, raising the temperature of the first catalytic reactor 11 to a temperature range in which the catalyst layer of the first catalytic reactor 11 is activated (step S103).

[0030] This makes it possible to stabilize combustion in the combustor 12 and ensure a stable heat source for the ammonia reformer 1 without having to separately provide a highly combustible fuel such as fossil fuels.

[0031] When the ammonia reformer 1 is started, no reformed gas with excellent combustibility is produced, and only ammonia gas is supplied to the combustor 12. However, as mentioned above, combustion may become unstable with only ammonia gas, which has a slow flame propagation speed. Therefore, when the ammonia reformer 1 is started, it is preferable to supply a separate combustion aid to the combustor 12, or to control the ignition device provided in the combustor 12 to operate until reformed gas is supplied.

[0032] <Second Embodiment> A second embodiment of the ammonia reforming apparatus according to the present invention will be described, focusing on the parts that differ from the first embodiment. The ammonia reforming apparatus 2 in this embodiment differs from the ammonia reforming apparatus 1 in that it further comprises a second catalytic reactor 21 and an electric heater 22.

[0033] When the demand from the gas engine 41 connected downstream of the ammonia reformer 1 shown in Figure 2 increases, and the flow rate of ammonia supplied to the first catalytic reactor 11 increases, a larger amount of heat is required for the decomposition of the ammonia. Therefore, in order to maintain the temperature of the first catalytic reactor 11, the amount of reformed gas supplied to the combustor 12 must be increased, which temporarily reduces the amount of reformed gas supplied to the gas engine 41.

[0034] Therefore, this embodiment is conceivable. Figure 5 is a diagram showing the configuration of the ammonia reformer 2. Similar to the first embodiment, the ammonia gas obtained via the heat exchanger 32 is supplied to the first catalytic reactor 11 after flow rate adjustment by valve 51, and to the second catalytic reactor 21 after flow rate adjustment by valve 54. The ammonia gas supplied to the second catalytic reactor 21 is decomposed in the second catalytic reactor 21, which has become high temperature due to the heat obtained by the electric heater 22, according to the reaction equation shown in equation (1), and the resulting reformed gas is supplied as fuel to the combustor 12.

[0035] The second catalytic reactor 21 mainly comprises a catalyst layer and a reaction vessel housing the catalyst layer. The catalyst layer contains, but is not limited to, at least one metal selected from nickel, ruthenium, cobalt, iron, palladium, platinum, gold, silver, and copper. The reaction vessel is, but is not limited to, stainless steel due to its corrosion resistance.

[0036] Here, in order to carry out the decomposition shown in equation (1) with a 100% reaction rate, reaction heat equivalent to about 15% of the lower heating value of ammonia is required. By operating the ammonia reformer 2 according to the flow described later, the reaction heat in the first catalytic reactor 11 that is additionally required when the demand for reformed gas at the customer increases or when the customer starts up is compensated for. However, since it is not necessary to generate the same amount of reformed gas as in the first catalytic reactor 11, the reaction vessel volume of the second catalytic reactor 21 may be smaller than that of the first catalytic reactor 11, preferably 15% or less by volume ratio. This makes it possible to reduce the cost of the second catalytic reactor 21, to rapidly raise the temperature of the second catalytic reactor 21 using the electric heater 22 described later, and to suppress the amount of electricity required to operate the electric heater 22.

[0037] Furthermore, as mentioned above, the reformed gas of ammonia, hydrogen, and nitrogen, obtained by decomposing a portion of the ammonia gas into hydrogen and nitrogen, is generally known to have better flammability than ammonia gas, and contributes to the stable combustion of the combustor 12. The reaction rate of ammonia gas in the second catalytic reactor 21 is preferably 5% to 70%, but more preferably 30% to 60%.

[0038] The electric heater 22 may be positioned so as to be in thermal contact with the second catalytic reactor 21, and the electric heater 22 may be housed inside the reaction vessel of the second catalytic reactor 21. The power required to operate the electric heater 22 may be supplied from an external source, but may also be supplied from a battery electrically connected to the electric heater 22, and is not limited to these sources.

[0039] Figure 7 is a flowchart illustrating the operation of the ammonia reformer 2. The following explanation will follow the flow shown in this flowchart.

[0040] When the demand for reformed gas produced in the first catalytic reactor 11 increases, the electric heater 22 is activated and the heating of the second catalytic reactor 21 begins (step S201). After the second catalytic reactor 21 has risen to a predetermined temperature, the valve 54 opens and ammonia gas is supplied to the second catalytic reactor 21. Then, the ammonia decomposition reaction occurs in the second catalytic reactor 21 (step S202), and reformed gas of ammonia, hydrogen, and nitrogen is produced. All of the produced reformed gas is supplied to the combustor 12, where it is burned together with residual oxygen or air in the combustion exhaust gas of the gas engine 41 (step S102). The heat generated by the combustion is supplied to the first catalytic reactor 11, raising the temperature of the first catalytic reactor 11 to the temperature range in which the catalyst layer of the first catalytic reactor 11 is activated (step S103).

[0041] Furthermore, when the gas engine 41, which is the recipient of the reformed gas, is started, the electric heater 22 is activated and the heating of the second catalytic reactor 21 begins (step S201). After the second catalytic reactor 21 has risen to a predetermined temperature, the valve 54 is opened and ammonia gas is supplied to the second catalytic reactor 21. Then, the ammonia decomposition reaction occurs in the second catalytic reactor 21 (step S202), and reformed gas of ammonia, hydrogen, and nitrogen is produced. At this time, since the ammonia decomposition reaction is an endothermic reaction, heat is continuously supplied by the electric heater 22.

[0042] All of the generated reformed gas is supplied to the combustor 12, where it is burned together with the remaining oxygen or air in the combustion exhaust gas of the gas engine 41 (step S102). The heat generated by the combustion is supplied to the first catalytic reactor 11, raising the temperature of the first catalytic reactor 11 to the temperature range in which the catalyst layer of the first catalytic reactor 11 is activated (step S103). After the first catalytic reactor 11 has been heated to a predetermined temperature, the valve 51 opens and ammonia gas is supplied to the first catalytic reactor 11. Then, a decomposition reaction of ammonia gas occurs in the first catalytic reactor 11 (step S101), and reformed gas of ammonia, hydrogen, and nitrogen is produced.

[0043] The reformed gas generated is supplied to the gas engine 41 and the combustor 12 in a predetermined ratio by the valve 52. The reformed gas supplied to the combustor 12 is burned in the combustor 12 together with residual oxygen or air in the combustion exhaust gas of the gas engine 41 (step S102). The heat generated by the combustion is supplied to the first catalytic reactor 11, maintaining the first catalytic reactor 11 in a temperature range in which the catalyst layer of the first catalytic reactor 11 is activated (step S103), and the operation of the electric heater 22 and the supply of ammonia gas to the second catalytic reactor 21 are stopped (step S203).

[0044] This means that when the demand for the supplied reformed gas increases, or when the reformed gas supply facility starts up, the heat source necessary for ammonia decomposition can be obtained from electricity, eliminating the need for separate combustion fuel and achieving carbon neutrality.

[0045] <Other Embodiments> The catalyst layer of the second catalytic reactor 21 may be a metal honeycomb structure, and the electric heater 22 may be an induction heater. Here, the support material in the metal honeycomb catalyst layer may be aluminum or stainless steel, but is not limited to these. Furthermore, the supporting material in the metal honeycomb catalyst layer may contain at least one metal selected from nickel, ruthenium, cobalt, iron, palladium, platinum, gold, silver, and copper, but is not limited to these.

[0046] By using a conductive material for the catalyst layer of the second catalytic reactor 21 and employing an induction heater for the electric heater 22, the catalyst layer can be heated intensively, making it possible to rapidly raise the temperature of the second catalytic reactor 21 to the required temperature range.

[0047] The embodiments described above are merely examples and are not intended to limit the scope of the invention. The invention can be implemented in various other forms, and various omissions, substitutions, and modifications are permitted without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the claims and their equivalents. [Explanation of symbols]

[0048] 1 Ammonia reforming unit 1 2 Ammonia reforming unit 2 11. First catalytic reactor 12 Combustor 13. Supply Line 1 14. Second supply line 21 Second catalytic reactor 22 Electric heater 31 Ammonia tank 32, 33, 34 heat exchanger 41 Gas engine 51, 52, 53, 54 valves

Claims

1. A reforming apparatus that decomposes ammonia to generate hydrogen, The reforming apparatus comprises a first catalytic reactor having a first catalyst layer, a combustor, a first supply line, a second supply line, an induction heating heater, and a second catalytic reactor having a second catalyst layer which is a metal honeycomb structure. The first catalytic reactor generates a first gas containing at least hydrogen from ammonia, The first supply line is connected to the downstream side of the first catalytic reactor, The second supply line branches off from the first supply line and is connected to the combustor. The induction heater heats the second catalytic reactor, The second catalytic reactor generates a second gas containing at least hydrogen from ammonia. The combustor burns part or all of the first gas supplied through the second supply line, and the second gas. The first catalyst layer and the second catalyst layer contain at least one metal selected from nickel, ruthenium, cobalt, iron, palladium, platinum, gold, silver, and copper. An ammonia reforming apparatus in which the volume of the second catalytic reactor is 15% or less of the volume of the first catalytic reactor.

2. The ammonia reforming apparatus according to claim 1, wherein the reaction rate of ammonia in the first catalytic reactor or the second catalytic reactor is 5% or more and 60% or less.

3. A method for operating an ammonia reforming apparatus according to claim 1, The aforementioned operating method comprises a first catalytic reaction step, a combustion step, a heating step, an electric heating step, and a second catalytic reaction step. The first catalytic reaction step generates a first gas containing at least hydrogen from ammonia, The electric heating step involves raising the temperature of the second catalytic reactor with the induction heater, The second catalytic reaction step generates a second gas containing at least hydrogen from ammonia, The combustion step burns part or all of the first gas and the second gas. The above-mentioned heating step is a method for operating an ammonia reforming apparatus, wherein the heating step is used to raise the temperature of the first catalytic reactor using the heat of combustion generated in the combustion step.

4. A method for starting an ammonia reforming apparatus according to claim 1, The aforementioned startup method comprises an electric heating step, a first catalytic reaction step, a second catalytic reaction step, a combustion step, a temperature rise step, and a stop step. The electric heating step involves heating the second catalytic reactor with the induction heater, The second catalytic reaction step generates a second gas containing at least hydrogen from ammonia, The combustion step involves burning the second gas, The heating step involves heating the first catalytic reactor with the heat of combustion generated in the combustion step. The first catalytic reaction step generates a first gas containing at least hydrogen from ammonia, The stopping step is a method for starting an ammonia reforming apparatus, wherein the stopping step stops the heating in the electric heating step and the generation of the second gas in the second catalytic reaction step.

Images