Ammonia Engine System

Abstract

To provide an ammonia engine system capable of preventing ammonia supplied to a vaporizer, an ammonia engine and a reformer from being released into the atmosphere.SOLUTION: An ammonia engine system 1 includes: a relief valve 26 opened when pressure in liquid ammonia piping 23 in which liquid ammonia flows from an ammonia storage tank 21 to a vaporizer 22 reaches specified pressure or higher; a relief valve 27 opened when pressure in ammonia gas piping 24, 25 in which ammonia gas flows from the vaporizer 22 to a main injector 5 and a reforming injector 13 reaches specified pressure or higher; and an ammonia holding tank 28 connected to the relief valves 26, 27 via drain piping 29, 30. The ammonia holding tank 28 includes: a casing 31 having an introduction port 36 for introducing the liquid ammonia and the ammonia gas; and an adsorbent 32 disposed in the casing 31 and adsorbing the liquid ammonia and the ammonia gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ammonia engine system. [Background technology]

[0002] As a conventional ammonia engine system, for example, a technology as described in Patent Document 1 is known. The ammonia engine system described in Patent Document 1 includes an engine body, an ammonia injector that injects ammonia toward each engine intake passage of the engine body, a hydrogen generating device that generates hydrogen from liquid ammonia, and a hydrogen injector that injects hydrogen toward each engine intake passage of the engine body. The hydrogen generating device includes a tank that stores liquid ammonia, an evaporator that heats and vaporizes the liquid ammonia, a supply pipe through which a portion of the gaseous ammonia generated by the evaporator flows toward the ammonia injector, a decomposer that decomposes the gaseous ammonia generated by the evaporator, an inlet pipe through which air supplied to the decomposer flows, and a supply pipe through which hydrogen generated by the decomposer flows toward the hydrogen injector. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2012 / 090739 Summary of the Invention [Problem to be solved by the invention]

[0004] In an ammonia engine system such as the above-mentioned conventional technology, gaseous ammonia is supplied to the engine body (ammonia engine) and the cracker (reformer). At this time, if the pressure in the pipes through which the liquid and gaseous ammonia flow becomes higher than necessary due to an increase in the ambient temperature or the like, the pipes and the evaporator (carburetor) may be damaged, and a large amount of ammonia may be scattered into the surroundings. As a countermeasure against this, it is considered to provide a safety valve in the pipes through which the ammonia flows. However, when the pressure in the pipes exceeds a specified pressure, the safety valve opens, causing the ammonia to be released into the atmosphere.

[0005] An object of the present invention is to provide an ammonia engine system that can prevent ammonia supplied to a vaporizer, an ammonia engine, and a reformer from being released into the atmosphere. [Means for solving the problem]

[0006] An ammonia engine system according to one aspect of the present invention includes an ammonia engine that burns ammonia gas, a reformer that generates a reformed gas containing hydrogen by reforming the ammonia gas, a reformed gas piping through which the reformed gas generated by the reformer flows toward the ammonia engine, a first air supply unit that supplies air to the ammonia engine, a second air supply unit that supplies air to the reformer, a first ammonia supply valve that supplies ammonia gas toward the ammonia engine, a second ammonia supply valve that supplies ammonia gas toward the reformer, an ammonia storage tank that stores liquid ammonia, a vaporizer that vaporizes the liquid ammonia stored in the ammonia storage tank to generate ammonia gas, a liquid ammonia piping through which liquid ammonia flows from the ammonia storage tank to the vaporizer, and The device includes an ammonia gas piping through which ammonia gas flows to the second ammonia supply valve, a first safety valve disposed in the liquid ammonia piping and opening when the pressure in the liquid ammonia piping reaches or exceeds a specified pressure, a second safety valve disposed in the ammonia gas piping and opening when the pressure in the ammonia gas piping reaches or exceeds a specified pressure, and an ammonia holding tank connected to the first safety valve and the second safety valve via a drain piping and holding liquid ammonia discharged from the first safety valve and ammonia gas discharged from the second safety valve, the ammonia holding tank having a housing connected to the drain piping and having an inlet for introducing liquid ammonia and ammonia gas, and an adsorbent disposed in the housing for adsorbing the liquid ammonia and ammonia gas, and an ammonia flow path provided in the housing for guiding the liquid ammonia and ammonia gas introduced from the inlet to the adsorbent.

[0007] In such an ammonia engine system, liquid ammonia stored in an ammonia storage tank flows through a liquid ammonia pipe and is supplied to a vaporizer. Then, in the vaporizer, the liquid ammonia is vaporized to generate ammonia gas. The ammonia gas flows through an ammonia gas pipe and is supplied to a first ammonia supply valve and a second ammonia supply valve. Then, the first ammonia supply valve and the second ammonia supply valve supply the ammonia gas to the ammonia engine and the reformer, respectively. Also, air is supplied to the ammonia engine and the reformer. Then, the ammonia gas is reformed in the reformer to generate a reformed gas containing hydrogen, and the reformed gas is supplied to the ammonia engine. Then, in the ammonia engine, the ammonia gas is combusted together with the hydrogen in the reformed gas.

[0008] Here, when the pressure in the liquid ammonia pipe becomes equal to or higher than the specified pressure, the first safety valve opens, and liquid ammonia is discharged from the first safety valve. The liquid ammonia flows through the drain pipe and is supplied to the ammonia holding tank. When the pressure in the ammonia gas pipe becomes equal to or higher than the specified pressure, the second safety valve opens, and ammonia gas is discharged from the second safety valve. The ammonia gas flows through the drain pipe and is supplied to the ammonia holding tank. In the ammonia holding tank, liquid ammonia and ammonia gas are introduced into the housing from the inlet, and then flow through the ammonia flow path and are adsorbed by the adsorbent. In this way, even if the first safety valve and the second safety valve open, the liquid ammonia discharged from the first safety valve and the ammonia gas discharged from the second safety valve are held in the ammonia holding tank by the pressure in the liquid ammonia pipe and the ammonia gas pipe becoming equal to or higher than the specified pressure. This prevents the liquid ammonia supplied to the vaporizer and the ammonia gas supplied to the ammonia engine and the reformer from being discharged into the atmosphere.

[0009] The ammonia holding tank may further include a heat absorbing member disposed in the housing and absorbing heat generated from the adsorbent. In such a configuration, the heat absorbing member absorbs the heat generated when the liquid ammonia and ammonia gas are adsorbed by the adsorbent. Therefore, the adsorbent is prevented from becoming hot, and the adsorption performance of the adsorbent is sufficiently ensured.

[0010] The inlet may be provided in the upper part of the housing, and the heat absorbing member may be disposed above the adsorbent. In such a configuration, the adsorbent and the heat absorbing member are disposed in the housing with good space efficiency, and the heat generated when the liquid ammonia and the ammonia gas are adsorbed by the adsorbent is effectively absorbed by the heat absorbing member.

[0011] Between the adsorbent and the heat absorbing member, there is a space through which liquid ammonia and ammonia gas flow, and a connecting member is arranged to connect the adsorbent and the heat absorbing member, and a gap is provided between the heat absorbing member and the inner surface of the housing, and the gap and the space may form an ammonia flow path. In this configuration, the liquid ammonia and ammonia gas introduced into the housing from the inlet flow through the gap and the space in order and are adsorbed by the adsorbent. Therefore, the liquid ammonia and ammonia gas are guided to the adsorbent without performing hole processing on the heat absorbing member. In addition, the heat generated when the liquid ammonia and ammonia gas are adsorbed by the adsorbent is absorbed by the heat absorbing member through the connecting member.

[0012] The heat absorbing member may have a through hole penetrating the housing in the vertical direction, and the through hole may form an ammonia flow path. In such a configuration, the liquid ammonia and ammonia gas introduced into the housing from the inlet flow through the through hole of the heat absorbing member and are adsorbed by the adsorbent. Therefore, the liquid ammonia and ammonia gas can be guided to the adsorbent while reducing the vertical dimension of the ammonia holding tank. In addition, the heat generated when the liquid ammonia and ammonia gas are adsorbed by the adsorbent is directly absorbed by the heat absorbing member.

[0013] The inlet is provided at the top of the housing, and a plurality of adsorbents may be arranged in the vertical direction of the housing. In such a configuration, by reducing the thickness dimension of each adsorbent, even if the adsorbent expands by adsorbing liquid ammonia and ammonia gas, the liquid ammonia and ammonia gas can easily reach the entire area of ​​the adsorbent. Therefore, the lower area of ​​the adsorbent is prevented from becoming a wasted area that does not adsorb liquid ammonia and ammonia gas.

[0014] A heat absorbing member that absorbs heat generated from the adsorbents may be disposed on the upper side of each of the adsorbents. In this configuration, the heat generated when the liquid ammonia and ammonia gas are adsorbed by the adsorbents is absorbed by the heat absorbing member. Therefore, the adsorbents are prevented from becoming hot, and the adsorption performance of the adsorbents is sufficiently ensured. Effect of the Invention

[0015] According to the present invention, ammonia supplied to the vaporizer, the ammonia engine, and the reformer can be prevented from being released into the atmosphere. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic configuration diagram showing an ammonia engine system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the ammonia adsorption tank shown in FIG. [Diagram 3] FIG. 1 is a schematic configuration diagram showing an ammonia engine system as a comparative example. [Figure 4] 3 is a cross-sectional view showing a modification of the ammonia holding tank shown in FIG. 2. [Diagram 5] FIG. 5 is a plan view of the heat absorbing member shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0018] Fig. 1 is a schematic diagram showing an ammonia engine system according to one embodiment of the present invention. In Fig. 1, an ammonia engine system 1 of this embodiment is mounted in an engine room of a vehicle. The ammonia engine system 1 includes an ammonia engine 2, an intake pipe 3, an exhaust pipe 4, a main injector 5, and a main throttle valve 6.

[0019] The ammonia engine 2 is an engine that burns ammonia (NH3) gas. In the ammonia engine 2, hydrogen (H2) gas is mixed into the ammonia gas to promote the combustion of the flame-retardant ammonia gas. The ammonia engine 2 is, for example, a four-cylinder engine. The ammonia engine 2 has four combustion chambers in which the ammonia gas is burned together with the hydrogen gas to generate exhaust gas.

[0020] The intake pipe 3 is connected to an intake port (not shown) of the ammonia engine 2. The intake pipe 3 is a pipe through which air flows to be supplied to the ammonia engine 2. An air cleaner 7 is disposed in the intake pipe 3 to remove foreign matter such as dust and dirt contained in the air.

[0021] The exhaust pipe 4 is connected to an exhaust port (not shown) of the ammonia engine 2. The exhaust pipe 4 is a pipe through which exhaust gas generated by the ammonia engine 2 flows.

[0022] The main injector 5 is a fuel injection valve that injects ammonia gas into an intake port or a combustion chamber of the ammonia engine 2. The main injector 5 is disposed for each cylinder of the ammonia engine 2. The main injector 5 constitutes a first ammonia supply valve that supplies ammonia gas to the ammonia engine 2.

[0023] The main throttle valve 6 is disposed in the intake pipe 3 between the air cleaner 7 and the ammonia engine 2. The main throttle valve 6 is a flow rate control valve that controls the flow rate of air supplied to the ammonia engine 2.

[0024] The intake pipe 3 and the main throttle valve 6 constitute a first air supply unit 8 that supplies air to the ammonia engine 2.

[0025] The ammonia engine system 1 also includes a reformer 10 , an air pipe 11 , a reforming throttle valve 12 , a reforming injector 13 , a reformed gas pipe 14 , a cooler 15 , and a stop valve 16 .

[0026] The reformer 10 generates reformed gas containing hydrogen by reforming ammonia gas using heat generated by burning ammonia gas. The reformer 10 has a cylindrical housing 17, and a reforming section 18 and an electric heater 19 housed in the housing 17. The housing 17 is made of a metal material such as stainless steel that is resistant to corrosion by ammonia.

[0027] The reforming section 18 has an ATR catalyst 18a having, for example, a honeycomb structure. The ATR catalyst 18a is an autothermal reforming catalyst that burns ammonia gas and uses the combustion heat (autothermal heat) of the ammonia gas to decompose the ammonia gas into hydrogen to reform the ammonia gas. As the ATR catalyst 18a, for example, a cobalt-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, a palladium-based catalyst, or the like is used.

[0028] The electric heater 19 is disposed upstream of the reforming section 18 inside the housing 17. When power is applied to the electric heater 19, the electric heater 19 generates heat, and uses the generated heat to heat the reforming section 18. At this time, the heat generated by the electric heater 19 is transmitted to the reforming section 18 through the gas flowing inside the housing 17, and is also transmitted to the reforming section 18 through the housing 17 itself.

[0029] The air pipe 11 connects the intake pipe 3 and the reformer 10. One end of the air pipe 11 is connected to a position in the intake pipe 3 between the air cleaner 7 and the main throttle valve 6. The other end of the air pipe 11 is connected to a gas inlet portion 17a of a housing 17 of the reformer 10. The air pipe 11 is a pipe through which air supplied to the reformer 10 flows. The reforming throttle valve 12 is disposed in the air pipe 11. The reforming throttle valve 12 is a flow control valve that controls the flow rate of air supplied to the reformer 10.

[0030] The air pipe 11 and the reforming throttle valve 12 constitute a second air supply unit 20 that supplies air to the reformer 10.

[0031] The reforming injector 13 is a fuel injection valve that injects ammonia gas into the air pipe 11 between the reforming throttle valve 12 and the reformer 10. The reforming injector 13 constitutes a second ammonia supply valve that supplies ammonia gas toward the reformer 10.

[0032] The reformed gas pipe 14 connects the reformer 10 and the intake pipe 3. One end of the reformed gas pipe 14 is connected to a gas outlet portion 17b of a housing 17 of the reformer 10. The other end of the reformed gas pipe 14 is connected to a portion of the intake pipe 3 between the main throttle valve 6 and the ammonia engine 2. The reformed gas pipe 14 is a pipe through which the reformed gas generated by the reformer 10 flows toward the ammonia engine 2.

[0033] The cooler 15 is disposed in the reformed gas pipe 14. The cooler 15 cools the reformed gas by, for example, exchanging heat between the reformed gas and engine cooling water for cooling the ammonia engine 2.

[0034] The stop valve 16 is disposed in the reformed gas pipe 14 downstream of the cooler 15. The stop valve 16 is an on-off valve that opens and closes the reformed gas pipe 14.

[0035] The ammonia engine system 1 also includes an ammonia storage tank 21, a vaporizer 22, a liquid ammonia pipe 23, ammonia gas pipes 24, 25, safety valves 26, 27, an ammonia holding tank 28, and drain pipes 29, 30.

[0036] The ammonia storage tank 21 stores ammonia in a liquid state. That is, the ammonia storage tank 21 stores liquid ammonia. The vaporizer 22 vaporizes the liquid ammonia stored in the ammonia storage tank 21 to generate ammonia gas.

[0037] The liquid ammonia piping 23 connects the ammonia storage tank 21 and the vaporizer 22. The liquid ammonia piping 23 is a piping through which liquid ammonia flows from the ammonia storage tank 21 to the vaporizer 22. The liquid ammonia piping 23 is formed of a metal material such as stainless steel that has corrosion resistance against ammonia.

[0038] The ammonia gas pipe 24 connects the vaporizer 22 and each main injector 5. The ammonia gas pipe 24 is a pipe through which ammonia gas flows from the vaporizer 22 to each main injector 5.

[0039] The ammonia gas pipe 25 connects the vaporizer 22 and the reforming injector 13. The ammonia gas pipe 25 is a pipe through which ammonia gas flows from the vaporizer 22 to the reforming injector 13. One end of the ammonia gas pipe 25 is connected to the ammonia gas pipe 24. The ammonia gas pipes 24 and 25 are formed of the same metal material as the liquid ammonia pipe 23.

[0040] The safety valve 26 is disposed in the liquid ammonia pipe 23. The safety valve 26 is a pressure regulating valve (first safety valve) that opens when the pressure in the liquid ammonia pipe 23 reaches or exceeds a specified pressure. The specified pressure of the safety valve 26 is set to a pressure that will not cause the liquid ammonia pipe 23 to burst, for example. When the safety valve 26 opens, liquid ammonia is discharged from an outlet 26a of the safety valve 26.

[0041] The safety valve 27 is disposed in the ammonia gas pipe 24. The safety valve 27 is disposed upstream (on the vaporizer 22 side) of the connection part of the ammonia gas pipe 24 with the ammonia gas pipe 25. The safety valve 27 is a pressure regulating valve (second safety valve) that opens when the pressure in the ammonia gas pipe 24 reaches or exceeds a specified pressure. The specified pressure of the safety valve 27 is set to a pressure that does not cause the ammonia gas pipes 24, 25 to burst, for example. When the safety valve 27 opens, ammonia gas is discharged from an exhaust port 27a of the safety valve 27.

[0042] The ammonia holding tank 28 is connected to the safety valves 26, 27 via drain pipes 29, 30, respectively. One end of the drain pipe 29 is connected to the outlet 26a of the safety valve 26. The other end of the drain pipe 29 is connected to the ammonia holding tank 28. One end of the drain pipe 30 is connected to the outlet 27a of the safety valve 27. The other end of the drain pipe 30 is connected to the drain pipe 29. The drain pipes 29, 30 are formed of the same metal material as the liquid ammonia pipe 23.

[0043] The liquid ammonia discharged from outlet 26a of safety valve 26 flows through drain piping 29 and is supplied to ammonia holding tank 28. The ammonia gas discharged from outlet 27a of safety valve 27 flows through drain piping 30, 29 and is supplied to ammonia holding tank 28. The ammonia holding tank 28 holds the liquid ammonia discharged from outlet 26a of safety valve 26 and the ammonia gas discharged from outlet 27a of safety valve 27.

[0044] Fig. 2 is a cross-sectional view of the ammonia holding tank 28. In Fig. 2, the ammonia holding tank 28 has a housing 31, and an adsorbent 32 and a heat absorbing member 33 disposed within the housing 31.

[0045] The housing 31 has a cylindrical container 34 with a bottom and a circular lid 35 fixed to the upper end of the container 34. An inlet 36 for introducing liquid ammonia and ammonia gas into the housing 31 is provided in the center of the lid 35. The drain pipe 29 is connected to the center of the lid 35. Specifically, the drain pipe 29 is connected to an inner wall surface that defines the inlet 36 in the center of the lid 35. As a result, the liquid ammonia and ammonia gas that have flowed through the drain pipe 29 are introduced into the housing 31 from the inlet 36. The housing 31 is formed of a metal material such as stainless steel.

[0046] The adsorbent 32 and the heat absorbing member 33 are arranged alternately in a plurality (two in this case) of units in the vertical direction of the housing 31. That is, in the housing 31, the adsorbent 32, the heat absorbing member 33, the adsorbent 32 and the heat absorbing member 33 are layered in this order from the bottom to the top of the housing 31. The adsorbent 32 and the heat absorbing member 33 have a circular shape in a plan view.

[0047] The adsorbent 32 adsorbs liquid ammonia and ammonia gas. The adsorbent 32 physically adsorbs ammonia when it generates heat and desorbs ammonia when it absorbs heat. The adsorbent 32 expands when it physically adsorbs ammonia and contracts when it desorbs ammonia. As such an adsorbent 32, a compound of an alkaline earth metal such as Be, Mg, or Ca and a halogen element such as F, Cl, or Br is used. As the adsorbent 32, zeolite, activated carbon, or the like may also be used.

[0048] The heat absorbing member 33 absorbs the heat generated from the adsorbent 32. The heat absorbing member 33 is made of a metal material such as stainless steel. As the heat absorbing member 33, a packaged heat storage material or the like may be used.

[0049] As described above, the adsorbent 32 expands when it adsorbs ammonia. Therefore, in a normal state where the adsorbent 32 does not adsorb ammonia, the diameter of the adsorbent 32 is smaller than the diameter of the heat absorbing member 33. In addition, in a normal state, a gap is provided between the lower adsorbent 32 and the bottom surface of the container 34, and a gap is provided between the upper adsorbent 32 and the lower heat absorbing member 33.

[0050] A connecting member 37 is disposed between the adsorbent 32 and the heat absorbing member 33. The connecting member 37 connects the adsorbent 32 and the heat absorbing member 33. The connecting member 37 has a space 38 through which liquid ammonia and ammonia gas flow. The space 38 faces the adsorbent 32. As the connecting member 37 having such a space 38, for example, a wire mesh or the like is used.

[0051] The lower connecting member 37 is fixed to the bottom surface of the container 34 via a plurality of pillars 39. The upper connecting member 37 is fixed to the lower heat absorbing member 33 via a plurality of pillars 39. In this way, the adsorbent 32, the heat absorbing member 33 and the connecting member 37 are supported in a stacked state by the container 34. The upper heat absorbing member 33 faces the inlet 36.

[0052] An annular gap 40 through which liquid ammonia and ammonia gas flow is provided between the adsorbent 32 and the heat absorbing member 33 and the inner surface 34a of the container 34. The gap 40 communicates with a space 38 provided in the connecting member 37.

[0053] The gap 40 and the space 38 constitute an ammonia flow path that guides the liquid ammonia and ammonia gas introduced into the housing 31 from the inlet 36 to the adsorbent 32. The liquid ammonia and ammonia gas introduced into the housing 31 from the inlet 36 flow through the gap 40 and the space 38 to reach the upper surface of the adsorbent 32, and also flow through the gap 40 to reach the side surface of the adsorbent 32. The liquid ammonia and ammonia gas then enter the inside of the adsorbent 32 from the upper surface and side surface of the adsorbent 32 and are adsorbed.

[0054] In the ammonia engine system 1 as described above, when an ignition switch (not shown) is turned on, the electric heater 19 is energized, whereby the reforming section 18 is heated by the electric heater 19 and the stop valve 16 is opened.

[0055] In addition, liquid ammonia is supplied from an ammonia storage tank 21 to a vaporizer 22 by a pump (not shown), and the liquid ammonia is vaporized in the vaporizer 22 to generate ammonia gas. The ammonia gas flows through ammonia gas pipes 24, 25 and is supplied to the main injector 5 and the reforming injector 13.

[0056] When the main throttle valve 6 opens, air is supplied to the ammonia engine 2. When the reforming injector 13 and the reforming throttle valve 12 open, ammonia gas and air are supplied to the reforming section .

[0057] When the temperature of the reformer 18 reaches an activation temperature (combustion temperature), the ammonia gas is combusted by the ATR catalyst 18a. Specifically, ammonia and oxygen in the air undergo a chemical reaction (exothermic reaction) as shown in the following formula. NH3+3 / 4O2→1 / 2N2+3 / 2H2O …(A)

[0058] Then, the temperature of the reformer 18 further rises due to the heat of combustion of the ammonia gas. Then, when the temperature of the reformer 18 reaches a reaction temperature (reforming temperature), the ammonia gas is reformed by the ATR catalyst 18a. Specifically, as shown in the following formula, a decomposition reaction of ammonia occurs (endothermic reaction), and a reformed gas containing hydrogen is generated. NH3→3 / 2H2+1 / 2N2…(B)

[0059] The reformed gas flows through the reformed gas pipe 14 and the intake pipe 3 and is supplied to the ammonia engine 2. Furthermore, the main injector 5 opens, so that ammonia gas is supplied to the ammonia engine 2. Then, in the ammonia engine 2, the ammonia gas is combusted together with the hydrogen in the reformed gas.

[0060] Incidentally, when the temperature in the engine room of the vehicle becomes too high due to an increase in the outside air temperature or the like, the pressure in the liquid ammonia pipe 23 and the ammonia gas pipes 24, 25 may reach an abnormal value. However, when the pressure in the liquid ammonia pipe 23 reaches a specified pressure, the safety valve 26 opens. When the pressure in the ammonia gas pipes 24, 25 reaches a specified pressure, the safety valve 27 opens. This prevents the liquid ammonia pipe 23, the ammonia gas pipes 24, 25, and the vaporizer 22 from bursting.

[0061] However, as shown in Fig. 3, if the ammonia holding tank 28 and the drain pipes 29, 30 are not provided, the following problems occur. That is, when the pressure in the liquid ammonia pipe 23 reaches a specified pressure, liquid ammonia leaks into the atmosphere even if the safety valve 26 opens. Also, when the pressure in the ammonia gas pipes 24, 25 reaches a specified pressure, ammonia gas leaks into the atmosphere even if the safety valve 27 opens.

[0062] In response to such a problem, in this embodiment, when the pressure in the liquid ammonia pipe 23 becomes equal to or higher than a specified pressure, the safety valve 26 opens, and liquid ammonia is discharged from the safety valve 26. The liquid ammonia flows through the drain pipe 29 and is supplied to the ammonia holding tank 28. When the pressure in the ammonia gas pipes 24 and 25 becomes equal to or higher than a specified pressure, the safety valve 27 opens, and ammonia gas is discharged from the safety valve 27. The ammonia gas flows through the drain pipes 30 and 29 and is supplied to the ammonia holding tank 28. In the ammonia holding tank 28, the liquid ammonia and ammonia gas are introduced into the housing 31 from the inlet 36, and then flow through the gap 40 and the space 38 to be adsorbed by the adsorbent 32. In this way, when the pressure in the liquid ammonia pipe 23 and the ammonia gas pipes 24 and 25 becomes equal to or higher than the specified pressure, even if the safety valve 26 and the safety valve 27 are opened, the liquid ammonia discharged from the safety valve 26 and the ammonia gas discharged from the safety valve 27 are held in the ammonia holding tank 28. This prevents the liquid ammonia supplied to the vaporizer 22 and the ammonia gas supplied to the ammonia engine 2 and the reformer 10 from being released into the atmosphere.

[0063] Here, it is also possible to simply store the liquid ammonia discharged from the safety valve 26 and the ammonia gas discharged from the safety valve 27 in a tank without adsorbing them in the adsorbent 32. In this case, however, the size of the tank becomes significantly larger (for example, about 20 times larger). In this embodiment, by disposing the adsorbent 32 inside the housing 31, it is possible to recover the liquid ammonia discharged from the safety valve 26 and the ammonia gas discharged from the safety valve 27 while making the size of the ammonia holding tank 28 sufficiently smaller than when the liquid ammonia and ammonia gas are simply stored in a tank.

[0064] In this embodiment, the heat generated when the liquid ammonia and the ammonia gas are adsorbed by the adsorbent 32 is absorbed by the heat absorbing member 33. Therefore, the adsorbent 32 is prevented from becoming hot, and the adsorption performance of the adsorbent 32 is sufficiently ensured.

[0065] In this embodiment, the heat absorbing member 33 is disposed above the adsorbent 32. Therefore, the adsorbent 32 and the heat absorbing member 33 are disposed in the housing 31 with good space efficiency, and the heat generated when the liquid ammonia and the ammonia gas are adsorbed by the adsorbent 32 is effectively absorbed by the heat absorbing member 33.

[0066] In this embodiment, the liquid ammonia and ammonia gas introduced into the housing 31 from the inlet 36 flow through the gap 40 between the heat absorbing member 33 and the inner side surface 34a of the housing 31 and the space 38 provided in the connecting member 37, and are adsorbed by the adsorbent 32. Therefore, the liquid ammonia and ammonia gas are guided to the adsorbent 32 without the need for hole processing in the heat absorbing member 33. In addition, the heat generated when the liquid ammonia and ammonia gas are adsorbed into the adsorbent 32 is absorbed by the heat absorbing member 33 via the connecting member 37.

[0067] In addition, in this embodiment, by reducing the thickness dimension of the multiple adsorbents 32 arranged in the vertical direction of the housing 31, even if the adsorbent 32 expands by adsorbing liquid ammonia and ammonia gas, the liquid ammonia and ammonia gas tend to reach the entire area of ​​the adsorbent 32. Therefore, the lower area of ​​the adsorbent 32 is prevented from becoming a wasted area that does not adsorb liquid ammonia and ammonia gas.

[0068] Fig. 4 is a cross-sectional view showing a modified example of the ammonia holding tank 28 shown in Fig. 2. In Fig. 4, the ammonia holding tank 28 of this modified example has the above-mentioned housing 31 and adsorbent 32, and a heat absorbing member 43.

[0069] The heat absorbing member 43 is provided with a plurality of (four in this example) through holes 44 penetrating the housing 31 in the up-down direction. These through holes 44 form an ammonia flow path that guides the liquid ammonia and ammonia gas introduced into the housing 31 from the inlet 36 to the adsorbent 32. The through holes 44 are provided so that the liquid ammonia and ammonia gas are adsorbed by most of the adsorbent 32. The through holes 44 are arranged so as to be point symmetric with respect to the radial center G of the heat absorbing member 43, as shown in Fig. 5, for example. The number of through holes 44 may be one.

[0070] The liquid ammonia and ammonia gas introduced into the housing 31 from the inlet 36 flow through the through holes 44 of the heat absorbing member 43 to reach the upper surface of the adsorbent 32, and also flow through the gaps 40 to reach the side surface of the adsorbent 32. Then, the liquid ammonia and ammonia gas enter the inside of the adsorbent 32 from the upper surface and side surface of the adsorbent 32 and are adsorbed.

[0071] In this embodiment, the liquid ammonia and ammonia gas introduced into the housing 31 from the inlet 36 flow through the through holes 44 of the heat absorbing member 43 and are adsorbed by the adsorbent 32. Therefore, the liquid ammonia and ammonia gas can be guided to the adsorbent 32 while reducing the vertical dimension of the ammonia holding tank 28. In addition, the heat generated when the liquid ammonia and ammonia gas are adsorbed by the adsorbent 32 is directly absorbed by the heat absorbing member 33.

[0072] The present invention is not limited to the above embodiment. For example, in the above embodiment, the adsorbent 32 and the heat absorbing member 33 are arranged alternately in the vertical direction of the housing 31, but the present invention is not particularly limited to such a form. The number of the adsorbent 32 and the heat absorbing member 33 or the heat absorbing member 43 may be one each.

[0073] In the above embodiment, only one inlet 36 is provided in the lid 35 of the housing 31, and liquid ammonia and ammonia gas are introduced into the housing 31 through this inlet 36, but the present invention is not limited to such an embodiment. The number of inlets 36 may be multiple.

[0074] Also, an inlet for introducing liquid ammonia and an inlet for introducing ammonia gas may be provided separately in the lid 35. In this case, the safety valve 26 and the inlet for introducing liquid ammonia may be connected by a drain pipe 29, and the safety valve 27 and the inlet for introducing ammonia gas may be connected by a drain pipe 30.

[0075] In addition, in the above embodiment, the inlet 36 is provided in the upper part of the housing 31, but this is not particularly limited, and the inlet 36 may be provided in the side part of the housing 31. In this case, the adsorbent 32 and the heat absorbing member 33 or 43 may be arranged side by side in the direction perpendicular to the up-down direction of the housing 31 within the housing 31.

[0076] In the above embodiment, the adsorbent 32 physically adsorbs liquid ammonia and ammonia gas, but the form is not particularly limited thereto, and for example, an adsorbent that chemically adsorbs liquid ammonia and ammonia gas may be used.

[0077] In the above embodiment, the heat absorbing member 33 or the heat absorbing member 43 that absorbs the heat generated from the adsorbent 32 is disposed in the housing 31, but the embodiment is not particularly limited to this, and the heat absorbing member 33 or the heat absorbing member 43 may be omitted. For example, a thermometer that detects the temperature of the housing 31 and a Peltier element that cools the housing 31 may be attached to the outer circumferential surface of the housing 31. In this case, when the temperature of the housing 31 rises to a predetermined temperature due to the heat generated from the adsorbent 32, the Peltier element is operated to release the heat to the outside of the housing 31. In such a configuration, the weight of the ammonia holding tank can be reduced by the amount of the heat absorbing member 33 or the heat absorbing member 43 not being present.

[0078] In the above embodiment, the reforming unit 18 has the ATR catalyst 18a that has both the function of burning ammonia gas and the function of decomposing the ammonia gas into hydrogen, but is not limited to such a form. The reforming unit 18 may have a combustion catalyst that burns ammonia gas and a reforming catalyst that decomposes the ammonia gas into hydrogen separately.

[0079] In addition, in the above embodiment, the reforming section 18 is heated by the electric heater 19, but the present invention is not limited to such a configuration. For example, the reforming section 18 may be heated by using a combustor such as a tubular flame. [Explanation of symbols]

[0080] Reference Signs List 1...ammonia engine system, 2...ammonia engine, 5...main injector (first ammonia supply valve), 8...first air supply section, 10...reformer, 13...reformed injector (second ammonia supply valve), 14...reformed gas piping, 20...second air supply section, 21...ammonia storage tank, 22...vaporizer, 23...liquid ammonia piping, 24, 25...ammonia gas piping, 26...safety valve (first safety valve), 27...safety valve (second safety valve), 28...ammonia holding tank, 29, 30...drain piping, 31...housing, 32...adsorbent, 33...heat absorbing member, 34a...inner surface, 36...inlet, 37...connecting member, 38...space (ammonia flow path), 40...gap (ammonia flow path), 43...heat absorbing member, 44...through hole (ammonia flow path).

Claims

1. an ammonia engine in which ammonia gas is burned; a reformer that generates a reformed gas containing hydrogen by reforming the ammonia gas; a reformed gas pipe through which the reformed gas generated by the reformer flows toward the ammonia engine; A first air supply unit that supplies air to the ammonia engine; A second air supply unit that supplies air to the reformer; a first ammonia supply valve that supplies the ammonia gas toward the ammonia engine; a second ammonia supply valve that supplies the ammonia gas toward the reformer; an ammonia storage tank for storing liquid ammonia; a vaporizer for vaporizing the liquid ammonia stored in the ammonia storage tank to generate the ammonia gas; a liquid ammonia pipe through which the liquid ammonia flows from the ammonia storage tank to the vaporizer; an ammonia gas pipe through which the ammonia gas flows from the vaporizer to the first ammonia supply valve and the second ammonia supply valve; a first safety valve disposed in the liquid ammonia pipe and opening when the pressure in the liquid ammonia pipe becomes equal to or higher than a specified pressure; a second safety valve disposed in the ammonia gas piping and opening when the pressure in the ammonia gas piping becomes equal to or higher than a specified pressure; an ammonia holding tank connected to the first safety valve and the second safety valve via a drain pipe, for holding the liquid ammonia discharged from the first safety valve and the ammonia gas discharged from the second safety valve; the ammonia holding tank includes a housing connected to the drain pipe and having an inlet for introducing the liquid ammonia and the ammonia gas, and an adsorbent disposed in the housing and adsorbing the liquid ammonia and the ammonia gas; The ammonia engine system includes an ammonia flow path provided in the housing to guide the liquid ammonia and the ammonia gas introduced from the inlet to the adsorbent.

2. 2. The ammonia engine system according to claim 1, wherein the ammonia holding tank further comprises a heat absorbing member disposed within the housing and configured to absorb heat generated from the adsorbent.

3. The inlet is provided in an upper portion of the housing, 3. The ammonia engine system according to claim 2, wherein the heat absorbing member is disposed above the adsorbent.

4. a space through which the liquid ammonia and the ammonia gas flow is provided between the adsorbent and the heat absorbing member, and a connecting member is disposed to connect the adsorbent and the heat absorbing member; A gap is provided between the heat absorbing member and an inner surface of the housing, The ammonia engine system according to claim 3 , wherein the gap and the space form the ammonia flow path.

5. The heat absorbing member has a through hole that passes through the housing in a vertical direction, The ammonia engine system according to claim 3 , wherein the through-hole forms the ammonia flow path.

6. The inlet is provided in an upper portion of the housing, The ammonia engine system according to claim 1 , wherein a plurality of the adsorbents are arranged in the vertical direction of the casing.

7. 7. The ammonia engine system according to claim 6, wherein a heat absorbing member that absorbs heat generated from the adsorbents is disposed above each of the plurality of adsorbents.

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