Combustor and ammonia engine system

Abstract

A combustor and an ammonia engine system are provided. A burner (40) is provided with: a housing (41) having an open first end and a closed second end (41b); an introduction unit that introduces the fuel and the oxidizing gas into the housing (41) so as to generate a tubular flow (F1) in the housing (41); a spark plug (44) disposed at the second end (41b); and an ignition means for generating spark (P1) between the positive electrode (45) and the negative electrode (46) of the spark plug (44). The positive electrode (45) and the negative electrode (46) are respectively disposed at positions such that the distance (L1) between the positive electrode (45) and the negative electrode (46) is shorter than the distance (L2) between the positive electrode (45) and the inner peripheral surface (41d) of the case (41), so that a flame (P2) generated between the positive electrode (45) and the negative electrode (46) by a spark (P1) is formed only in a negative pressure region (A1) generated locally within the case (41).

Description

Technical Field

[0001] The present disclosure relates to combustors and ammonia engine systems. Background Art

[0002] The burner described in Patent Document 1 has a cylindrical shell, an introduction part, and a spark plug. The first end of the shell is open, and the second end of the shell is closed. Inside the shell, fuel mixed with oxidizing gas and combustion gas generated by combustion of the fuel flow. The introduction part introduces the fuel and oxidizing gas into the shell in a manner that generates a tubular flow in the shell. The spark plug is arranged at the second end in the shell. The combustion gas is ignited by the spark plug, thereby generating a flame in the shell. The combustion gas is discharged from the first end of the shell.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-93114

[0004] In order to exhaust a large amount of combustion gas from the burner as quickly as possible, it is desirable that a large amount of combustion gas be generated by the burner as quickly as possible after the flame is generated. Summary of the invention

[0005] A burner according to one embodiment of the present disclosure includes: a cylindrical shell having an open first end and a closed second end, and in which a fuel mixed with an oxidizing gas and a combustion gas generated by the combustion of the fuel flow; at least one introduction portion, which is configured to introduce the fuel and the oxidizing gas into the shell in a manner that generates a tubular flow in the shell, and is configured so that the tubular flow generates a negative pressure region locally in the shell; a spark plug, which is arranged at the second end in the shell and has a positive electrode and a negative electrode; and an ignition unit, which is configured to generate a spark between the positive electrode and the negative electrode. The positive electrode and the negative electrode are respectively arranged at positions where the distance between the positive electrode and the negative electrode is shorter than the distance between the positive electrode and the inner peripheral surface of the shell, so that the flame generated between the positive electrode and the negative electrode due to the spark is formed only in the negative pressure region.

[0006] An ammonia engine system according to one embodiment of the present disclosure comprises: the burner described above; a reforming catalyst configured to be warmed up by the combustion gas; and an ammonia engine configured to be supplied with hydrogen gas exhausted from the reforming catalyst. The distance between the positive electrode and the negative electrode is a distance that enables the ammonia engine to be started within the start time required by a vehicle equipped with the ammonia engine system. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of an ammonia engine system according to an embodiment.

[0008] Figure 2 Yes means Figure 1 Schematic diagram of the burner, spark plug and ignition unit of an ammonia engine system.

[0009] Figure 3 yes Figure 2 Cross-sectional view at line 3-3.

[0010] Figure 4 yes Figure 3 Cross-sectional view at line 4-4.

[0011] Figure 5 Yes Figure 2 A cross-sectional view showing an enlarged portion of a burner.

[0012] Figure 6 Yes means Figure 2 A coordinate diagram showing the relationship between the radial position of a burner casing and the pressure inside the casing.

[0013] Figure 7 It is a graph showing the time taken to start the ammonia engine of the embodiment and the comparative example. DETAILED DESCRIPTION

[0014] Below, use Figure 1 to Figure 7 An embodiment of a burner and an ammonia engine system will be described.

[0015] <Schematic structure of ammonia engine system>

[0016] like Figure 1 As shown, the ammonia engine system 10 includes an ammonia engine 11. The ammonia engine system 10 of the present embodiment is mounted on an engine-type vehicle 50. The ammonia engine 11 uses ammonia gas (NH3) as fuel. A combustion chamber 11a is formed inside the ammonia engine 11.

[0017] The ammonia engine system 10 includes an intake air flow path 12, an air filter 19, a main injector 14, and a main throttle valve 15. Air is introduced into the combustion chamber 11a from the intake air flow path 12. The air filter 19 removes foreign matter such as dust and dirt contained in the air. The air filter 19 is provided at the end of the intake air flow path 12. The air from which foreign matter has been removed by the air filter 19 flows into the intake air flow path 12.

[0018] The main injector 14 is, for example, an electromagnetic injection valve. Ammonia is supplied to the main injector 14 from an ammonia supply unit (not shown). The main injector 14 supplies ammonia to the intake passage 12 by injecting ammonia into the intake passage 12. The ammonia supplied from the main injector 14 to the intake passage 12 is introduced into the combustion chamber 11a together with the air flowing in the intake passage 12.

[0019] The main throttle valve 15 is provided on the upstream side of the portion where the ammonia gas is supplied from the main injector 14 in the intake flow path 12. The main throttle valve 15 is, for example, an electromagnetic flow control valve capable of adjusting the opening of the intake flow path 12.

[0020] The ammonia engine system 10 has an exhaust flow path 13 and an exhaust catalyst unit 16. Exhaust gas generated in the combustion chamber 11a is introduced from the combustion chamber 11a into the exhaust flow path 13. The exhaust catalyst unit 16 is arranged in the exhaust flow path 13. The exhaust catalyst unit 16 has a three-way catalyst 17 and an SCR catalyst 18. The three-way catalyst 17 removes ammonia from the exhaust gas by oxidizing the ammonia remaining in the exhaust gas flowing in the exhaust flow path 13. The three-way catalyst 17 is activated by the heat of the exhaust gas. The SCR catalyst 18 is arranged on the downstream side of the exhaust flow path 13 than the three-way catalyst 17. The SCR catalyst 18 is a selective catalytic reduction catalyst. The SCR catalyst 18 uses ammonia to reduce nitrogen oxides (NOx) contained in the exhaust gas flowing in the exhaust flow path 13 into nitrogen (N2). In addition, the SCR catalyst 18 captures and removes the ammonia that has passed through the three-way catalyst 17.

[0021] The ammonia engine system 10 has a reformer 23. The reformer 23 has a box-shaped housing portion 23a in which a space is formed. A reforming catalyst 23b is arranged inside the housing portion 23a. In other words, the ammonia engine system 10 has a reforming catalyst 23b. It is also possible that a carrier of a honeycomb structure, not shown, is arranged inside the housing portion 23a. It is also possible that the reforming catalyst 23b is arranged inside the housing portion 23a by coating the reforming catalyst 23b on the carrier. The reforming catalyst 23b has the function of decomposing ammonia into hydrogen and the function of burning ammonia. The reforming catalyst 23b is, for example, an ATR (Autothermal Reformer) type ammonia reforming catalyst. The reformer 23 reforms the ammonia through the reforming catalyst 23b, thereby generating a reformed gas containing hydrogen.

[0022] The ammonia engine system 10 includes a reformed gas flow path 31, a cooler 32, and a shutoff valve 33. One end of the reformed gas flow path 31 is connected to the reformer 23. The other end of the reformed gas flow path 31 is connected to the intake flow path 12 at a downstream side of the main throttle valve 15. The reformed gas generated by the reformer 23 is introduced into the reformed gas flow path 31, and the reformed gas is introduced from the reformed gas flow path 31 to the intake flow path 12.

[0023] The cooler 32 cools the reformed gas flowing in the reformed gas flow path 31. The cooler 32 cools the reformed gas by, for example, exchanging heat between cooling water flowing inside the cooler 32 and the reformed gas. The reformed gas cooled by the cooler 32 is introduced into the intake flow path 12 through the reformed gas flow path 31. Thus, damage to intake system components such as the main throttle valve 15 caused by the heat of the reformed gas can be suppressed. As the reformed gas is cooled, the volume expansion of the reformed gas is suppressed, so that the gas easily flows from the intake flow path 12 into the combustion chamber 11a.

[0024] The shutoff valve 33 is provided on the downstream side of the cooler 32 in the reformed gas flow path 31. The shutoff valve 33 is, for example, an on-off valve that opens and closes the reformed gas flow path 31.

[0025] The ammonia engine system 10 includes a first air flow path 24a, a first injector 25, and a first throttle valve 26. One end of the first air flow path 24a is connected to the upstream side of the main throttle valve 15 of the intake flow path 12. The other end of the first air flow path 24a is connected to the reformer 23. A portion of the air introduced into the intake flow path 12 via the air filter 19 is introduced into the first air flow path 24a. Air is introduced from the first air flow path 24a to the reformer 23.

[0026] The first injector 25 is, for example, an electromagnetic injection valve. Ammonia gas is supplied to the first injector 25 from an ammonia gas supply unit (not shown). The first injector 25 supplies ammonia gas to the first air flow path 24a by injecting ammonia gas into the first air flow path 24a. The ammonia gas supplied from the first injector 25 to the first air flow path 24a is introduced into the reformer 23 together with the air flowing in the first air flow path 24a.

[0027] The first throttle valve 26 is provided in the first air flow path 24a at the upstream side of the position to which the ammonia gas is supplied from the first injector 25. The first throttle valve 26 is, for example, an electromagnetic flow control valve capable of adjusting the opening degree of the first air flow path 24a.

[0028] The ammonia engine system 10 includes a second air flow path 24b, a chamber 27, a second injector 28, a second throttle valve 29, and a burner 40. One end of the second air flow path 24b is connected to the first air flow path 24a at an upstream side of the first throttle valve 26. The other end of the second air flow path 24b is connected to the chamber 27. A portion of the air flowing in the first air flow path 24a is introduced into the second air flow path 24b. The chamber 27 is box-shaped and has a space formed therein. Air is introduced from the second air flow path 24b into the space inside the chamber 27.

[0029] The second injector 28 is, for example, an electromagnetic injection valve. Ammonia is supplied to the second injector 28 from an ammonia supply unit (not shown). The second injector 28 supplies ammonia to the space inside the chamber 27 by injecting ammonia into the space inside the chamber 27. The air introduced into the chamber 27 from the second air flow path 24b and the ammonia supplied to the chamber 27 from the second injector 28 are mixed inside the chamber 27. Thus, ammonia mixed with air is generated inside the chamber 27. In the present embodiment, ammonia is equivalent to fuel, and air is equivalent to oxidizing gas. Ammonia mixed with air is introduced from the chamber 27 into the burner 40.

[0030] The second throttle valve 29 is provided in the second air flow path 24b. The second throttle valve 29 is, for example, an electromagnetic flow control valve capable of adjusting the opening degree of the second air flow path 24b.

[0031] The burner 40 generates combustion gas by burning ammonia gas as fuel. The combustion gas generated by the burner 40 is introduced into the reformer 23 .

[0032] The ammonia engine system 10 includes a temperature sensor 35, an ignition switch 36, and a control unit 37. The temperature sensor 35 detects the temperature of the reformer 23. When the driver of the vehicle 50 operates the ignition switch 36, the ignition switch 36 outputs an operation signal to the control unit 37. The control unit 37 is composed of a CPU, a RAM, a ROM, an input / output interface, and the like.

[0033] The control unit 37 performs various controls based on, for example, the detection value of the temperature sensor 35 and the operation signal of the ignition switch 36. The control unit 37 controls the main injector 14, the main throttle valve 15, the first injector 25, the first throttle valve 26, the second injector 28, the second throttle valve 29, the shutoff valve 33, and the like.

[0034] <Control obtained by the control unit>

[0035] The control unit 37 executes a start control for starting the ammonia engine 11. The control unit 37 executes the start control on the condition that it is determined based on the operation signal of the ignition switch 36 that the ignition switch 36 is turned on.

[0036] In the start control, the control unit 37 causes ammonia gas to be injected from the first injector 25 and the second injector 28. The control unit 37 causes the first throttle valve 26, the second throttle valve 29, and the shutoff valve 33 to be opened. Next, in the start control, the control unit 37 starts the ammonia engine 11 by controlling a starter motor (not shown) in such a manner as to crank the ammonia engine 11. Furthermore, in the start control, the control unit 37 causes ammonia gas to be injected from the main injector 14, and causes the main throttle valve 15 to be opened.

[0037] In the startup control, the control unit 37 determines whether the temperature of the reformer 23 is above a predetermined temperature based on the detection value of the temperature sensor 35. The predetermined temperature is a temperature at which ammonia can burn, for example, about 200°C. When the control unit 37 determines that the temperature of the reformer 23 is above the predetermined temperature, the injection of ammonia from the second injector 28 is stopped, and the second throttle valve 29 is closed. As a result, the introduction of air and ammonia supplied from the chamber 27 to the burner 40 is stopped. The combustion of ammonia in the burner 40 is stopped, and thereby the introduction of combustion gas from the burner 40 to the reformer 23 is stopped. In this way, the startup control based on the control unit 37 ends.

[0038] Alternatively, the control unit 37 may adjust the opening of the main throttle valve 15 and change the injection timing of the main injector 14 from the end of the start control to the stop of the ammonia engine 11. Alternatively, the control unit 37 may appropriately adjust the amount of air introduced from the first air flow path 24a to the reformer 23 by adjusting the opening of the first throttle valve 26. Alternatively, the control unit 37 may appropriately change the injection timing of the first injector 25.

[0039] The control unit 37 performs a stop control for stopping the ammonia engine 11. The control unit 37 performs the stop control on the condition that it determines based on the operation signal of the ignition switch 36 that the ignition switch 36 is turned off.

[0040] In the stop control, the control unit 37 stops the injection of ammonia gas from the main injector 14 and the first injector 25. In the stop control, the control unit 37 closes the main throttle valve 15, the first throttle valve 26, and the shutoff valve 33. Thus, the ammonia engine 11 stops.

[0041] <Combustion reaction in the reformer>

[0042] Air and ammonia are introduced into the reformer 23 from the first air flow path 24a, and combustion gas is introduced into the reformer 23 from the burner 40. The reforming catalyst 23b is warmed up by the combustion gas. As a result, ammonia reacts chemically with oxygen in the air as shown in the following formula 1. This combustion reaction of ammonia occurs in the reformer 23.

[0043] NH3+3 / 4O2→3 / 2H2O+1 / 2N2+Q…(Formula 1)

[0044] The reformer 23 generates a mixed gas containing water (H2O) and nitrogen (N2) by the combustion reaction of the ammonia gas. The temperature of the reformer 23 is increased by the combustion heat generated by the combustion reaction of the ammonia gas.

[0045] <Reforming reaction in the reformer>

[0046] When the temperature of the reformer 23 reaches a temperature at which reforming is possible, reforming of ammonia by the reforming catalyst 23b begins. The temperature at which reforming is possible is, for example, about 300° C. to 400° C. In the reforming of ammonia, specifically, a reforming reaction occurs in the reformer 23 in which ammonia is decomposed into hydrogen (H2) and nitrogen by combustion heat, as shown in the following formula 2.

[0047] NH3→3 / 2H2+1 / 2N2-Q…(Formula 2)

[0048] Through the reforming reaction, the reformer 23 generates a reformed gas containing hydrogen and nitrogen. The reformed gas is discharged from the reforming catalyst 23b. That is, the hydrogen contained in the reformed gas is discharged from the reforming catalyst 23b. After being introduced from the reformer 23 into the reformed gas flow path 31, the reformed gas is introduced into the intake flow path 12 via the reformed gas flow path 31.

[0049] <Supply of reformed gas to combustion chamber>

[0050] The reformed gas introduced from the reformed gas flow path 31 into the intake flow path 12 is supplied from the intake flow path 12 to the combustion chamber 11a of the ammonia engine 11. That is, the hydrogen exhausted from the reforming catalyst 23b is supplied to the ammonia engine 11. The reformed gas is supplied to the combustion chamber 11a together with the ammonia supplied from the main injector 14 to the intake flow path 12 and the air in the intake flow path 12. The ammonia is mixed with the hydrogen in the reformed gas in the combustion chamber 11a, so the ammonia is easily burned in the combustion chamber 11a. In the combustion chamber 11a, the ammonia is burned together with the hydrogen in the reformed gas. After the start control based on the control unit 37 is started, the ammonia is burned together with the hydrogen in the combustion chamber 11a, whereby the ammonia engine 11 is started.

[0051] <Burner Details>

[0052] like Figure 2 As shown, the burner 40 has a cylindrical shell 41. The first end 41a of the shell 41 is open. A blocking wall 42 is provided at the second end 41b of the shell 41. The blocking wall 42 is, for example, in the shape of a circular plate. The blocking wall 42 blocks the second end 41b of the shell 41. Thus, the second end 41b of the shell 41 is blocked. The shell 41 and the blocking wall 42 are made of a conductive metal material. The conductive metal material is, for example, stainless steel.

[0053] like Figure 3As shown, the burner 40 has four introduction parts 43. The introduction part 43 is, for example, tubular and has a flow path 43a inside. One end of the introduction part 43 is connected to the chamber 27, and the other end of the introduction part 43 is connected to the shell 41. In a cross section orthogonal to the axis L of the shell 41, the four introduction parts 43 are respectively connected to the shell 41 in a manner that the flow path 43a extends along the tangent direction of the inner peripheral surface 41d of the shell 41. Alternatively, the introduction part 43 may be formed integrally with the shell 41. Alternatively, the introduction part 43 may be formed independently of the shell 41 and fixed to the shell 41.

[0054] The flow path 43a of the introduction portion 43 communicates with the interior of the housing 41 via an introduction hole 41c formed in the housing 41. Four introduction holes 41c are formed in the housing 41. The introduction holes 41c are formed, for example, in the middle portion of the housing 41 in the extending direction of the axis L of the housing 41. The four introduction holes 41c are spaced apart from each other at equal intervals in the circumferential direction of the housing 41.

[0055] Ammonia gas mixed with air is introduced from the inside of the chamber 27 into the flow path 43a of the introduction part 43. After flowing in the flow path 43a, the ammonia gas mixed with air is introduced from the flow path 43a into the inside of the housing 41. In this way, the introduction part 43 introduces ammonia gas as a fuel and air as an oxidizing gas into the housing 41. The introduction part 43 is connected to the housing 41 in such a manner that the flow path 43a extends in the tangential direction of the inner peripheral surface 41d of the housing 41, so that the ammonia gas and air introduced into the inside of the housing 41 from the introduction part 43 flow in the circumferential direction of the housing 41 along the inner peripheral surface 41d of the housing 41.

[0056] like Figure 2 As shown, the burner 40 has a spark plug 44. The spark plug 44 is arranged at the second end 41b in the housing 41. The spark plug 44 has a positive electrode 45 and a negative electrode 46. The positive electrode 45 and the negative electrode 46 are separated from each other in the radial direction of the housing 41. The positive electrode 45 is attached to the housing 41 via an insulating member 47 in a manner penetrating the blocking wall 42, for example. The insulating member 47 is made of an insulating material having pressure resistance and heat resistance, such as ceramics.

[0057] The positive electrode 45 and the negative electrode 46 are, for example, cylindrical and extend in the extension direction of the axis L of the housing 41. The terminal portion 45a of the positive electrode 45 in the extension direction of the axis L of the housing 41 is located inside the housing 41. Specifically, in the extension direction of the axis L of the housing 41, a part of the positive electrode 45 including the terminal portion 45a is arranged inside the housing 41, and the other part of the positive electrode 45 is arranged outside the housing 41. In the extension direction of the axis L of the housing 41, the terminal portion 45a of the positive electrode 45 is located between the introduction hole 41c of the housing 41 and the blocking wall 42.

[0058] The positive electrode 45 is disposed inside the case 41, for example, on the axis L of the case 41. The negative electrode 46 is disposed inside the case 41, for example, at a position offset from the axis L of the case 41 in the radial direction of the case 41 and at a position separated from the inner peripheral surface 41d of the case 41.

[0059] The burner 40 has an ignition unit 51. The ignition unit 51 has an igniter 52 and a power source 53. The power source 53 performs an on-operation and an off-operation of the igniter 52. Alternatively, the on-operation and the off-operation of the igniter 52 based on the power source 53 may be controlled by the control unit 37. Alternatively, in the start control, the on-operation of the igniter 52 obtained based on the power source 53 may be performed. The igniter 52 is connected to the positive electrode 45 via the wire 54. The igniter 52 supplies a pulse voltage to the positive electrode 45 via the wire 54.

[0060] <Flow of ammonia and air in the burner>

[0061] like Figure 4 As shown, the ammonia gas and air introduced into the housing 41 from the introduction portion 43 flow in the circumferential direction of the housing 41 along the inner peripheral surface 41d of the housing 41, thereby generating a tubular flow F1 of ammonia gas mixed with air in the housing 41. In other words, the introduction portion 43 introduces ammonia gas and air into the housing 41 in such a manner as to generate the tubular flow F1 in the housing 41. The ammonia gas mixed with air flows in the housing 41.

[0062] The ammonia gas and the air flow in the housing 41 in a tubular flow F1, and flow from the opening of the introduction hole 41c on the inner peripheral surface 41d toward the first end 41a and the second end 41b of the housing 41, respectively. The flow of the ammonia gas and the air from the opening of the introduction hole 41c on the inner peripheral surface 41d toward the second end 41b of the housing 41 is referred to as the gas flow F2. Figure 4 The gas flow F2 is schematically shown by the dashed arrows in FIG.

[0063] The ammonia gas and air flowing toward the second end 41b of the housing 41 as the gas flow F2 are turned back by the blocking wall 42 and flow toward the first end 41a of the housing 41. The flow of the ammonia gas and air from the second end 41b of the housing 41 toward the first end 41a is referred to as the gas flow F3. Figure 4 The gas flow F3 is schematically shown by the dashed arrows in FIG.

[0064] <Negative pressure area>

[0065] like Figure 5As shown, a negative pressure region A1 is generated locally in the shell 41 of the combustor 40. The negative pressure region A1 is generated by the tubular flow F1 flowing along the inner peripheral surface 41d of the shell 41. In detail, the negative pressure region A1 is a region including the center of the shell 41 in the radial direction of the shell 41. For example, the axis L of the shell 41 becomes the center of the negative pressure in the negative pressure region A1. In the space inside the shell 41, the region between the negative pressure region A1 and the inner peripheral surface 41d of the shell 41 in the radial direction of the shell 41 becomes the positive pressure region A2.

[0066] Figure 6 It is a coordinate diagram showing the relationship between the radial position of the casing 41 and the pressure in the casing 41 . Figure 6 The horizontal axis represents the radial position of the shell 41 in the cross section of the shell 41 along the axis L. The position with a value of 0 (zero) on the horizontal axis represents the axis L of the shell 41. The range greater than 0 (zero) on the horizontal axis represents a position on one side of the axis L in the radial direction of the shell 41, and the range less than 0 (zero) represents a position on the other side of the axis L in the radial direction of the shell 41. In the range greater than 0 (zero) on the horizontal axis, a larger value on the horizontal axis represents a position closer to the inner circumferential surface 41d of the shell 41. In the range less than 0 (zero) on the horizontal axis, a smaller value on the horizontal axis represents a position closer to the inner circumferential surface 41d of the shell 41. Figure 6 The vertical axis represents the pressure in the housing 41. A range greater than 0 (zero) in the vertical axis represents that the pressure in the housing 41 is positive pressure, and a range less than 0 (zero) represents that the pressure in the housing 41 is negative pressure. Figure 6 As shown in FIG. 1 , the central portion of the housing 41 in the radial direction becomes negative pressure. The other portions of the housing 41 become positive pressure. Figure 6 It is also clear from the coordinate diagram that a negative pressure area A1 and a positive pressure area A2 are generated inside the shell 41.

[0067] <Combustion of Ammonia>

[0068] like Figure 2 and Figure 4 As shown, when a high voltage is applied to the positive electrode 45 from the igniter 52, discharge occurs between the positive electrode 45 and the negative electrode 46, thereby generating a spark P1 between the positive electrode 45 and the negative electrode 46. That is, the ignition unit 51 generates the spark P1 between the positive electrode 45 and the negative electrode 46. The spark P1 ignites the ammonia gas inside the housing 41. Alternatively, the igniter 52 may be disconnected by the power supply 53 at the timing when the ammonia gas inside the housing 41 is ignited.

[0069] like Figure 5 As shown in FIG. 1 , if spark P1 ignites ammonia, the ammonia burns to generate flame P2. Flame P2 is as shown in FIG. Figure 5The dotted hatching is schematically shown. Flame P2 is generated between the positive electrode 45 and the negative electrode 46 due to the spark P1. In addition, the spark P1 is generated at the area where the distance between the positive electrode 45 and the negative electrode 46 is the shortest. Therefore, flame P2 is also generated at the area where the distance between the positive electrode 45 and the negative electrode 46 is the shortest. In the present embodiment, the area where the distance between the positive electrode 45 and the negative electrode 46 is the shortest is the area between the positive electrode 45 and the negative electrode 46 in the radial direction of the shell 41. If ammonia burns, combustion gas is generated inside the shell 41. Combustion gas generated by the combustion of ammonia as a fuel flows inside the shell 41. The combustion gas is introduced into the reformer 23 from the first end 41a of the shell 41.

[0070] like Figure 5 As shown in the flame flow F4 indicated by the solid arrow, the flame P2 immediately after being generated flows in a manner close to the center of the negative pressure in the negative pressure area A1, that is, the axis L of the shell 41. The flame P2 grows from the second end 41b to the first end 41a of the shell 41 by the gas flow F3 of ammonia and air generated in the negative pressure area A1. The growth of the flame P2 promotes the generation of combustion gas generated by the combustion of ammonia in the shell 41. The closer the flame P2 is to the first end 41a of the shell 41, the closer it is to the inner peripheral surface 41d of the shell 41. Near the inner peripheral surface 41d of the shell 41, the flame P2 grows in the form of a tubular flow F1 in the shell 41.

[0071] <Position of positive and negative electrodes>

[0072] The positive electrode 45 and the negative electrode 46 are respectively arranged at positions where the distance L1 between the positive electrode 45 and the negative electrode 46 is shorter than the distance L2 between the positive electrode 45 and the inner peripheral surface 41d of the shell 41. The distance L1 is the shortest distance between the positive electrode 45 and the negative electrode 46. The distance L2 is the shortest distance between the positive electrode 45 and the inner peripheral surface 41d of the shell 41. The distances L1 and L2 in this embodiment are distances in the radial direction of the shell 41.

[0073] The discharge from the positive electrode 45 is performed on the negative electrode 46 and the inner peripheral surface 41d of the case 41, whichever is the shorter in distance from the positive electrode 45. The distance L1 between the positive electrode 45 and the negative electrode 46 is shorter than the distance L2 between the positive electrode 45 and the inner peripheral surface 41d of the case 41, so that the discharge is generated between the positive electrode 45 and the negative electrode 46. As a result, the spark P1 is generated between the positive electrode 45 and the negative electrode 46.

[0074] The positive electrode 45 and the negative electrode 46 are arranged so that the flame P2 generated by the spark P1 is formed only in the negative pressure area A1. Specifically, the generation area of ​​the flame P2 having a width of the distance L1 in the area between the positive electrode 45 and the negative electrode 46 is located in the negative pressure area A1.

[0075] <Relationship between the distance between the positive and negative electrodes and the start-up time>

[0076] The larger the distance L1 between the positive electrode 45 and the negative electrode 46, the larger the size of the flame P2 immediately after being generated. Under the condition that the positive electrode 45 and the negative electrode 46 are arranged so that the flame P2 is formed only in the negative pressure area A1, the larger the size of the flame P2 immediately after being generated, the faster the flame P2 grows from the second end 41b to the first end 41a of the housing 41. Therefore, a large amount of combustion gas can be quickly generated in the burner 40.

[0077] like Figure 1 As shown, the reforming catalyst 23b is warmed up by introducing the combustion gas generated in the burner 40 into the reformer 23. If a large amount of combustion gas can be quickly generated in the burner 40, the reforming catalyst 23b can be quickly warmed up. Therefore, the reformed gas containing hydrogen can be quickly generated by the reformer 23. In addition, the reformed gas can be quickly introduced from the reformer 23 to the combustion chamber 11a of the ammonia engine 11 via the reformed gas flow path 31 and the intake flow path 12, so the ammonia engine 11 can be quickly started. In this way, under the condition that the positive electrode 45 and the negative electrode 46 are arranged in such a way that the flame P2 is formed only in the negative pressure area A1, the larger the distance L1 between the positive electrode 45 and the negative electrode 46, the shorter the start-up time of the ammonia engine 11 can be. The distance L1 between the positive electrode 45 and the negative electrode 46 of the present embodiment is a distance that can start the ammonia engine 11 within the start-up time required by the vehicle 50 equipped with the ammonia engine system 10. The distance L1 between the positive electrode 45 and the negative electrode 46 is larger than, for example, the minimum distance required to ignite the ammonia gas and generate the flame P2 in association with the spark P1 .

[0078] like Figure 7 As shown, in the embodiment in which discharge is performed between the positive electrode 45 and the negative electrode 46 and the comparative example in which discharge is performed between the positive electrode 45 and the inner peripheral surface 41d of the housing 41, the time T taken to start the ammonia engine 11 is measured. Here, the time T is the time from when the ignition switch 36 is turned on to when the start of the ammonia engine 11 is completed. The start of the ammonia engine 11 is completed at the moment when the ammonia gas and the hydrogen gas start to burn together in the combustion chamber 11a. In this measurement, the distance L1 between the positive electrode 45 and the negative electrode 46 in the embodiment is 5 mm, and the distance L2 between the positive electrode 45 and the inner peripheral surface 41d of the housing 41 in the comparative example is 15 mm. Under the condition that the excess air ratio λ is around 1.1, the time T is measured multiple times in each of the embodiment and the comparative example. The excess air ratio λ is a value obtained by dividing the mass of the air actually supplied by the minimum air mass required theoretically. Figure 7In the experiment, the measured value of the embodiment is indicated by point E1, and the measured value of the comparative example is indicated by point E2. As indicated by points E1 and E2, the time T in the embodiment tends to be shorter than the time T in the comparative example. As is clear from the experimental results, in the embodiment in which the discharge is performed between the positive electrode 45 and the negative electrode 46, the time T required for starting the ammonia engine 11 tends to be shorter than in the comparative example in which the discharge is performed between the positive electrode 45 and the inner peripheral surface 41d of the housing 41.

[0079] [effect]

[0080] Next, the operation of this embodiment will be described.

[0081] Figure 5 In FIG. 4 , it is assumed that discharge is performed between the positive electrode 45 and the inner peripheral surface 41 d of the casing 41 as a comparative example. Figure 5 As shown by the double-dashed line, the flame P3 of the comparative example is generated between the positive electrode 45 and the inner peripheral surface 41d of the shell 41. Therefore, the flame P3 just after being generated in the comparative example is formed in the negative pressure area A1 and the positive pressure area A2. The part of the flame P3 formed in the positive pressure area A2 receives the flow of ammonia and air flowing near the inner peripheral surface 41d of the shell 41 toward the second end 41b, that is, the gas flow F2. The flame P3 in the comparative example flows in a manner close to the center of the negative pressure in the negative pressure area A1, that is, the axis L of the shell 41, as shown by the flame flow F5 shown by the hollow arrow of the double-dashed line. Due to the flow of ammonia and air generated in the negative pressure area A1, that is, the gas flow F3, the flame P3 grows from the second end 41b of the shell 41 toward the first end 41a. However, as mentioned above, a part of the flame P3 is affected by the gas flow F2, so that the flame P3 in the comparative example is not easy to grow from the second end 41b of the shell 41 toward the first end 41a.

[0082] In the present embodiment, the flame P2 is generated between the positive electrode 45 and the negative electrode 46. The flame P2 immediately after being generated flows in a manner close to the center of the negative pressure in the negative pressure area A1, that is, the axis L of the housing 41, as shown by the flame flow F4. The flame P2 grows from the second end 41b of the housing 41 toward the first end 41a due to the flow of ammonia and air generated in the negative pressure area A1, that is, the gas flow F3. Here, the positive electrode 45 and the negative electrode 46 are respectively arranged so that the flame P2 generated between the positive electrode 45 and the negative electrode 46 due to the spark P1 is formed only in the negative pressure area A1. Therefore, the flame P2 generated between the positive electrode 45 and the negative electrode 46 is not easily affected by the flow of ammonia and air toward the second end 41b flowing near the inner peripheral surface 41d of the housing 41, that is, the gas flow F2. Therefore, compared with the flame P3 generated in the comparative example, the flame P2 generated in the present embodiment is easy to grow from the second end 41b of the housing 41 toward the first end 41a.

[0083] [Effect]

[0084] According to the above-described embodiment, the following effects can be obtained.

[0085] (1) The positive electrode 45 and the negative electrode 46 are arranged so that the flame P2 generated between the positive electrode 45 and the negative electrode 46 by the spark P1 is formed only in the negative pressure area A1. Therefore, compared with the case where the flame P3 is generated between the positive electrode 45 and the inner peripheral surface 41d of the housing 41, the flame P2 grows faster from the second end 41b toward the first end 41a of the housing 41. Therefore, a large amount of combustion gas can be quickly generated in the burner 40.

[0086] (2) The reforming catalyst 23b is warmed up by the combustion gas generated in the burner 40. A large amount of combustion gas is quickly generated in the burner 40, thereby quickly warming up the reforming catalyst 23b. Therefore, hydrogen can be quickly generated by the reforming catalyst 23b. In addition, hydrogen can be quickly discharged from the reforming catalyst 23b to the ammonia engine 11, so the ammonia engine 11 can be started quickly.

[0087] [Change example]

[0088] The above-described embodiment can be implemented with modifications as follows. The above-described embodiment and the following modifications can be implemented in combination with each other within the scope of no technical contradiction.

[0089] The distance L1 between the positive electrode 45 and the negative electrode 46 may be equal to the minimum distance required to generate the flame P2 by igniting the ammonia gas accompanying the spark P1.

[0090] ○ Alternatively, the positive electrode 45 and the negative electrode 46 may be arranged to be separated from each other in a direction intersecting the radial direction of the housing 41. In this case, the flame P2 may be generated between the positive electrode 45 and the negative electrode 46 in a direction intersecting the radial direction of the housing 41. In this case, the positive electrode 45 and the negative electrode 46 are respectively arranged in such a manner that the flame P2 generated between the positive electrode 45 and the negative electrode 46 is formed only in the negative pressure area A1.

[0091] ○ The position of the positive electrode 45 inside the housing 41 may be a position deviated from the axis L of the housing 41. In short, if the positive electrode 45 and the negative electrode 46 are arranged so that the flame P2 generated between the positive electrode 45 and the negative electrode 46 is formed only in the negative pressure area A1, the positions of the positive electrode 45 and the negative electrode 46 inside the housing 41 can be appropriately changed.

[0092] The introduction part 43 is not limited to a structure that introduces ammonia gas mixed with air into the housing 41. For example, some of the multiple introduction parts 43 may introduce only ammonia gas into the housing 41, and other introduction parts 43 may introduce only air into the housing 41. In short, as long as the introduction part 43 is a structure that introduces ammonia gas and air into the housing 41 in a manner that generates a tubular flow F1 in the housing 41, it will not matter.

[0093] ○The number of inlet parts 43 of the burner 40 may be less than 3, or may be more than 5. In short, the burner 40 only needs to have at least one inlet part 43. In addition, the expression "at least one" used in this specification refers to "more than one" of the desired options. As an example, the expression "at least one" used in this specification means "only one option" or "both options" if the number of options is two. As another example, the expression "at least one" used in this specification means "only one option" or "a combination of any two or more options" if the number of options is more than 3.

[0094] The main injector 14 may be configured to directly inject ammonia gas into the combustion chamber 11 a .

[0095] The burner 40 and the ammonia engine system 10 may be configured to use a substance other than ammonia as fuel. For example, the burner 40 and the ammonia engine system 10 may use hydrocarbon gas or the like as fuel.

[0096] The burner 40 and the ammonia engine system 10 may be configured to use oxygen as the oxidizing gas.

[0097] The ammonia engine system 10 can also be applied to a hybrid vehicle 50 .

Claims

1. A burner comprising: A cylindrical casing having an open first end and a closed second end, and having a fuel mixed with an oxidizing gas and a combustion gas generated by combustion of the fuel flowing therein; at least one introduction portion configured to introduce the fuel and the oxidizing gas into the housing in a manner that generates a tubular flow in the housing, and configured so that the tubular flow generates a negative pressure region locally in the housing; a spark plug disposed at the second end in the housing and having a positive electrode and a negative electrode; and an ignition unit configured to generate a spark between the positive electrode and the negative electrode, The burner is characterized in that The positive electrode and the negative electrode are respectively arranged at positions where the distance between the positive electrode and the negative electrode is shorter than the distance between the positive electrode and the inner peripheral surface of the shell, so that the flame generated between the positive electrode and the negative electrode due to the spark is formed only in the negative pressure area.

2. An ammonia engine system, comprising: The burner according to claim 1; a reforming catalyst configured to be warmed by the combustion gas; and an ammonia engine configured to be supplied with hydrogen gas exhausted from the reforming catalyst, The ammonia engine system is characterized in that: The distance between the positive electrode and the negative electrode is a distance that allows the ammonia engine to be started within a start time required for a vehicle equipped with the ammonia engine system.

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