Ammonia combustion method and ammonia combustion system

Abstract

The present invention relates to a method for burning ammonia in which ammonia gas is burned in a combustion chamber (4), comprising: a step of separating hydrogen gas from ammonia gas; a step of supplying the separated hydrogen gas to the combustion chamber (4); a step of igniting and discharging the hydrogen gas supplied to the combustion chamber (4) and burning the hydrogen gas; and a step of igniting the ammonia gas in the combustion chamber (4) from the burned hydrogen gas.

Description

Technical Field

[0001] The present invention relates to a method for burning ammonia that is non-flammable and a combustion system for ammonia. Background Art

[0002] In recent years, along with the requirement to reduce carbon dioxide emissions, there has been an increasing expectation for ammonia, which does not emit carbon dioxide even when burned, as a fuel to replace carbon-based fuels. On the other hand, ammonia is a non-flammable fuel and has the characteristics of being more difficult to ignite (ignite) and having a slower combustion speed than carbon-based fuels. Specifically, the energy required to ignite a carbon-based fuel is about 80 mJ to 120 mJ, while the energy required to ignite ammonia is about 400 mJ to 600 mJ. Moreover, the laminar burning speed of ammonia is approximately 7 times slower than that of carbon-based fuels (for example, general hydrocarbon fuels such as methane gas and propane gas).

[0003] In a combustion system using such non-flammable ammonia as a fuel, unburned ammonia and nitrogen oxides are generated due to incomplete combustion of the fuel. Thus, various technical solutions for efficiently burning ammonia have been proposed (for example, Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-159705

[0006] However, when burning non-flammable fuels such as ammonia, there are problems such that it is very difficult to initially ignite ammonia compared to the case of burning currently widely used carbon-based fuels, and it is also very difficult to keep ammonia burning stably even after ignition. Summary of the Invention

[0007] An object of the present invention is to solve the above problems and provide a method for burning ammonia that can efficiently perform initial ignition of ammonia and keep ammonia burning stably even after ignition.

[0008] The combustion method according to the present invention is a method for burning ammonia in which ammonia is burned in a combustion chamber, and includes: a step of separating hydrogen from ammonia; a step of supplying the separated hydrogen to the combustion chamber; a step of igniting and burning the hydrogen supplied to the combustion chamber by discharge; and a step of igniting ammonia in the combustion chamber from the burned hydrogen.

[0009] In the combustion method of this invention, first hydrogen is burned. After the combustion chamber is heated to a certain degree, non-flammable ammonia is supplied, and the burning hydrogen extends the combustion to the supplied ammonia. Therefore, since highly flammable hydrogen is burned first and the ammonia is ignited by the burning hydrogen, the ammonia can be efficiently initially ignited, and the combustion of ammonia continues stably even after ignition.

[0010] In the combustion method of one embodiment, it further includes the step of supplying the above-mentioned ammonia to the above-mentioned combustion chamber.

[0011] In the combustion method of this invention, since the combustion energy can be easily changed by adjusting the amount of ammonia supplied to the combustion chamber, it can be easily adjusted to the energy required for various combustions such as engines of automobiles or motorcycles, high-temperature furnaces, and biomass.

[0012] In the combustion method of one embodiment, when the temperature in the above-mentioned combustion chamber reaches a specified temperature, the above-mentioned ammonia is supplied to the above-mentioned combustion chamber.

[0013] In the combustion method of this invention, since the temperature in the combustion chamber needs to be heated to a specified temperature, the initial ignition can be more efficiently carried out by ammonia.

[0014] In the combustion method of one embodiment, it further includes the step of detecting combustion state information indicating the combustion state of the above-mentioned ammonia; and the step of adjusting the supply amount of the above-mentioned hydrogen to the above-mentioned combustion chamber based on the detected combustion state information.

[0015] In the combustion method of this invention, since the supply amount of hydrogen can be quickly adjusted according to the combustion state of ammonia, the combustion of ammonia can continue stably more efficiently.

[0016] In the combustion method of one embodiment, the above-mentioned combustion state information is information related to the output of a turbine, and the turbine uses ionic current based on ions generated by the combustion of the above-mentioned ammonia or the energy brought by the combustion of the above-mentioned ammonia.

[0017] In the combustion method of this invention, the combustion state of ammonia is grasped based on the output of a turbine using ionic current brought by ions generated by the combustion of ammonia or the energy brought by the combustion of ammonia. Therefore, since the combustion state of ammonia can be grasped more accurately, the useless consumption of hydrogen can be further suppressed.

[0018] In the combustion method of one embodiment, in the above-mentioned step of separating and generating hydrogen from ammonia, ammonia is reformed by dielectric barrier discharge to separate and generate hydrogen.

[0019] In the combustion method of the present invention, since no additional hydrogen is required, the cost can be reduced.

[0020] On the other hand, the combustion method of the present invention is an ammonia combustion method in which ammonia is burned in a combustion chamber, and it includes: a step of separating and generating hydrogen from ammonia; a step of supplying the separated and generated hydrogen to the combustion chamber; a step of igniting and discharging the hydrogen supplied to the combustion chamber and burning the hydrogen; a step of supplying a mixed gas of the separated and generated hydrogen and ammonia to the combustion chamber; and a step of igniting the supplied mixed gas from the burned hydrogen.

[0021] In the combustion method of the present invention, since hydrogen is burned first, and after the combustion chamber is heated to a certain degree, it immediately continues to burn to a mixed gas of non-flammable ammonia and highly flammable hydrogen, the continuous combustion can be carried out more efficiently compared with only continuing to burn to ammonia.

[0022] In the combustion method of one embodiment, it further includes: a step of reducing the proportion of hydrogen in the mixed gas after igniting the mixed gas.

[0023] In the combustion method of the present invention, compared with the case of only continuing to burn to highly non-flammable ammonia, since the combustion state of ammonia can reach a more stable combustion state, the combustion of ammonia can continue more stably.

[0024] On the other hand, the combustion system of the present invention is an ammonia combustion system in which the input ammonia is burned in a combustion chamber, and it includes: a first pipe for supplying the ammonia to the combustion chamber; a first valve provided separately in the first pipe; a reformer for separating and generating hydrogen from the ammonia; a second pipe for supplying the separated and generated hydrogen to the combustion chamber; a second valve provided separately in the second pipe; a spark plug for igniting and discharging the hydrogen supplied to the combustion chamber and burning the hydrogen; and a control unit for controlling the opening and closing of the first valve and the second valve and the ignition and discharging of the spark plug.

[0025] In the combustion system of the present invention, the control unit that controls the ignition operation of the spark plug controls the opening and closing of the valves for supplying hydrogen and ammonia to the combustion chamber. Therefore, in the technology of efficiently burning ammonia, since there is no need to separately provide a control device for opening and closing the valves, an increase in manufacturing cost can be suppressed.

[0026] In the combustion system of one embodiment, the control unit first opens the second valve, starts the above-mentioned ignition and discharging to burn the hydrogen, and controls to open the first valve after the hydrogen burns.

[0027] In the combustion system of this invention, hydrogen is first burned. After the combustion chamber is heated to a certain degree, non-flammable ammonia is supplied, and the burning hydrogen spreads to the supplied ammonia. Therefore, since highly flammable hydrogen is burned first and the supplied ammonia is ignited from the burning hydrogen, the initial ignition of ammonia can be achieved efficiently, and the combustion of ammonia can continue stably even after ignition.

[0028] In a combustion system of an embodiment, it further includes: a temperature sensor that detects the temperature in the combustion chamber, and the control unit raises the temperature to a specified temperature based on the temperature in the combustion chamber detected by the temperature sensor.

[0029] In the combustion system of this invention, since hydrogen is first burned and after the combustion chamber is heated to a certain degree, it first spreads to a mixed gas of non-flammable ammonia and highly flammable hydrogen, the spread can be carried out more efficiently compared to only spreading to ammonia.

[0030] In a combustion system of an embodiment, it further includes: a combustion state detection unit that detects combustion state information indicating the combustion state of ammonia in the combustion chamber, and the control unit controls in such a way as to adjust the supply amount of the hydrogen to the combustion chamber based on the combustion state information detected by the combustion state detection unit.

[0031] In the combustion system of this invention, since the supply amount of hydrogen can be adjusted rapidly according to the combustion state of ammonia, the combustion of ammonia can continue stably more efficiently.

[0032] In a combustion system of an embodiment, the combustion state information is information related to the output of a turbine, and the turbine uses ionic current based on ions generated by the combustion of the ammonia or the energy brought by the combustion of the ammonia.

[0033] In the combustion system of the present invention, the output of a turbine that uses ionic current based on ions generated by the combustion of ammonia or the energy brought by the combustion of ammonia is used to grasp the combustion state of ammonia. Therefore, since the combustion state of ammonia can be grasped more reliably, the useless consumption of hydrogen can be further suppressed.

[0034] In a combustion system of an embodiment, the control unit reforms ammonia to separate and generate hydrogen by controlling dielectric barrier discharge in the reformer.

[0035] In the combustion system of the present invention, in a control unit for controlling the ignition operation of a spark plug, a dielectric barrier discharge for reforming a first fuel to produce a second fuel having higher flammability than the first fuel can be controlled. Therefore, in the above-described technology for efficiently burning ammonia, since a control device for dielectric barrier discharge for generating required hydrogen is not required, an increase in manufacturing cost can be suppressed.

[0036] According to the combustion method of the present invention, since hydrogen is first burned to raise the temperature of the combustion chamber to a certain level and then non-flammable ammonia is supplied, and the burning hydrogen spreads to the supplied ammonia, the initial ignition of ammonia can be efficiently achieved, and the combustion of ammonia can stably continue even after ignition. BRIEF DESCRIPTION OF THE DRAWINGS

[0037]

Figure 1

[0038]

Figure 2

[0039]

Figure 3

[0040]

Figure 4

[0041]

Figure 5

[0042]

Figure 6

[0043] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0044] Embodiment 1

[0045] Figure 1FIG. 0 is a partial cross-sectional side view of the combustion system 2 according to Embodiment 1 of the present invention and a block diagram of the constituent components around it. Figure 1 The combustion system 2 is made of tubular heat-resistant glass or stainless steel and includes: a combustion chamber 4 for burning the fuel introduced therein, a circular inlet 22 for feeding the fuel into the combustion chamber 4, a swirl vane (rotating vane) 23 located at the inlet 22 and disposed in the combustion chamber 4, a fuel tank 12a for storing ammonia (first fuel) with very high non-flammability, a reformer 13 as a hydrogen generation device for reforming ammonia by dielectric barrier discharge to generate hydrogen (second fuel) with higher flammability than the ammonia and supplying it to the combustion chamber 4, a fuel tank 12c for storing the hydrogen generated by the reformer 13, an air compressor 12b for supplying air as an oxidant, valves 21a to 21d for respectively adjusting the supply amounts of ammonia, hydrogen, and air, an igniter 14 supported by the bottom 18 of the combustion chamber 4, a spark plug 7 located near the igniter 14 and for igniting the igniter 14, and a control device 1 as a control unit for controlling the ignition operation of the spark plug 7 and the dielectric barrier discharge of the reformer 13 while also controlling the opening and closing of the valves 21a to 21d.

[0046] The above combustion system 2 is a combustion system for burning the introduced ammonia in the combustion chamber 4 and includes: a first pipe for supplying ammonia to the combustion chamber 4, a valve 21a provided in the first pipe, a reformer 13 for separating and generating hydrogen from ammonia, a second pipe for supplying the separated and generated hydrogen to the combustion chamber 4, a valve 21b provided in the second pipe, a spark plug 7 for performing ignition discharge on the hydrogen supplied to the combustion chamber 4 and burning the hydrogen, and a control device 1 for controlling the opening and closing of the valves 21a and 21b and the ignition discharge of the spark plug 7. Here, the valve 21a is provided separately from the first pipe, and the valve 21b is provided separately from the second pipe.

[0047] Figure 1 The spark plug 7 has: a discharge electrode 7a with a hooked tip and a ground electrode 7b with a hooked tip, and the discharge electrode 7a and the ground electrode 7b are respectively formed to protrude from the bottom 18 into the interior of the combustion chamber 4. Further, a high voltage is applied from the control device 1 to the discharge electrode 7a, whereby a spark is generated between the tip of the discharge electrode 7a and the tip of the ground electrode 7b, and then the hydrogen ejected from the igniter 14 is ignited.

[0048] In addition, Figure 1 the combustion system 2 includes: a combustion state detection unit (not shown) for detecting combustion state information indicating the combustion state of ammonia in the combustion chamber 4. Here, when the control device 1 determines based on the combustion state information detected by the combustion state detection unit that the ammonia has reached the optimal combustion state, the supply of hydrogen to the combustion chamber 4 is stopped.

[0049] For example, the above combustion state detection unit may also be an ion current detection unit (not shown) that detects the ion current generated by the combustion of ammonia. Here, the control device 1 controls in such a way that the ion current detection unit detects the ion current, calculates the ion current value, and controls the opening and closing of the valves 21a to 21d based on the calculated ion current value. The ion current detection unit includes an application electrode and a ground electrode, is present near the application electrode, and attracts the ions generated by combustion to the application electrode to generate an ion current. That is, the more ions generated by combustion, the greater the ion current flowing through. In addition, the ion current value is calculated by detecting the voltage proportional to the ion current, and based on the calculated ion current value, the difficult-to-observe combustion state of ammonia can be grasped, so that the combustion of ammonia can be controlled to continue stably.

[0050] Moreover, in the combustion method of the combustion system 2, there is a step of measuring the correlation between the parameter indicating the combustion state of ammonia and the ion current and setting the reference range of the ion current. In the step of continuing the combustion of ammonia, by setting the ion current detected by the ion current detection unit within this reference range, the optimal combustion state can be maintained.

[0051] In addition, the above combustion state detection unit may also be configured to detect output information such as the rotational speed of a turbine that utilizes the energy generated by the combustion of ammonia. In this case, when the control device 1 determines that the ammonia has reached the optimal combustion state based on the output information of the turbine, which is the combustion state information detected by the combustion state detection unit, the supply of hydrogen to the combustion chamber 4 is stopped.

[0052] Furthermore, Figure 1 the combustion system 2 is provided with a temperature sensor (not shown) for measuring the radiation temperature of the flame in the combustion chamber 4. Here, the temperature sensor is configured to be located outside the flame surface of the flame in the combustion chamber 4, and sends the temperature data measured by the temperature sensor to the control device 1, and the control device 1 controls the opening and closing of the valves 21a to 21d based on the temperature data.

[0053] Figure 1 The combustion chamber 4 includes: a main body portion 25 made of heat-resistant glass or stainless steel in the shape of a long and thin tube along the gravity direction X, a lid portion 20 covering the upper opening portion of the main body portion 25, and a bottom portion 18 covering the lower opening portion of the main body portion 25. In Figure 1 the center portion (central portion) of the bottom portion 18, there is provided a circular inlet 22 for feeding non-flammable ammonia into the combustion chamber 4. In addition, in Figure 1 the center portion of the lid portion 20, there is provided an outlet 24 for ejecting the flame.

[0054] The swirl blade 23 is supported by the bottom 18 of the combustion chamber 4 near the center when the combustion chamber 4 is cut horizontally. Ammonia is sent into the combustion chamber 4 as a swirl airflow S1 through the swirl blade 23. Here, by adjusting the valve 21 connected to the fuel tank 12a and the valve 21 connected to the air compressor 12b, ammonia of a specified concentration can be sent into the combustion chamber 4 as a swirl airflow S1. In addition, the swirl airflow S1 flowing in from the inlet 22 continuously diffuses and moves upward in a manner of swirling along the inner wall (inner peripheral surface) of the combustion chamber 4. The ammonia in the central part of the combustion chamber 4 is pulled by the flow, and in the central part of the combustion chamber 4, the ammonia forms a spiral shape and flows from the bottom to the top.

[0055] In addition, a plurality of pilot burners 14 are provided in the outer region of the swirl blade 23. Specifically, a plurality of pilot burners 14 are arranged at equal intervals near the inner wall of the combustion chamber 4 so as to surround the peripheral portion of the inlet 22 (the peripheral portion of the swirl blade 23) concentrically with the swirl blade 23, and hydrogen gas which is more flammable than ammonia gas is ejected. Here, by adjusting the valve 21b connected to the reformer 13 and the valve 21d connected to the air compressor 12b, a predetermined concentration of hydrogen gas can be fed to each pilot burner 14.

[0056] Figure 1 The reformer 13 comprises: a dielectric for defining an ammonia flow path, a high-voltage electrode arranged to be in contact with the dielectric, a hydrogen separation membrane which is opposite to the high-voltage electrode via an electrolyte and is grounded to serve as a ground electrode, a hydrogen flow path for extracting hydrogen separated by the hydrogen separation membrane, and a high-voltage power supply which is opposite to the high-voltage electrode and applies a bipolar pulse waveform to generate a dielectric barrier discharge between the hydrogen separation membrane and the high-voltage electrode. Here, hydrogen can be separated from ammonia with a high yield through the discharge action between the hydrogen separation membrane and the high-voltage electrode. That is, Figure 1 The reformer 13 is a plasma-based hydrogen generator.

[0057] Figure 2 Yes means have Figure 1 FIG. 1 is a block diagram of components of an ignition system 11 of a control device 1 . Figure 2 The ignition system 11 includes a spark plug 7, a dielectric barrier discharge reactor 8 disposed in a reformer 13 and generating a dielectric barrier discharge to weaken molecular bonds, and a control device 1 as a control unit for controlling the ignition operation and dielectric barrier discharge of the spark plug 7. Here, the discharge electrode 7a of the spark plug 7 is electrically connected to the dielectric barrier discharge reactor 8.

[0058] Figure 2The control device 1 includes: a drive circuit 30 for an ignition coil, an ignition coil 5, and a battery 6 of a power supply unit whose one terminal on the negative side is grounded. The ignition coil 5 includes: a primary coil L1, a secondary coil L2, and an iron core. One end of the primary coil L1 is connected to one end of the secondary coil L2 and the + side terminal of the positive electrode of the battery 6, and the other end of the primary coil L1 is connected to the collector terminal of an insulated gate bipolar transistor (hereinafter referred to as "IGBT") 31 to be described later through a primary current input terminal. The other end of the secondary coil L2 is electrically connected to a spark plug 7 and a dielectric barrier discharge reactor 8.

[0059] The drive circuit 30 for the ignition coil includes: a current detection unit 40 that detects a voltage corresponding to the primary current I1 flowing through the primary coil L1, an IGBT 31 as a switching element, and a drive unit 32 that controls the switching operation of the IGBT 31. In addition, the current detection unit 40 includes: a power supply 42 having a reference voltage Vref, a comparator 41, and a resistor 43 that detects the current flowing through the IGBT 31. Here, one end of the resistor 43 is connected to the emitter terminal E of the IGBT 31, and the other end of the resistor 43 is grounded.

[0060] The comparator 41 inputs the value of the voltage difference between both ends of the resistor 43 (detection voltage corresponding to the primary current Il flowing through the primary coil Ll) equivalent to the current Il flowing through the IGBT 31 to the non-inverting input terminal, and inputs the value of the reference voltage Vref to the inverting input terminal. Here, the comparator 41 compares the value between the voltage difference between both ends of the resistor 43 and the reference voltage Vref, generates a comparison result signal CO, and outputs the comparison result signal CO to the drive unit 32. That is, when the voltage difference between both ends of the resistor 43 is greater than the reference voltage Vref, the comparator 41 outputs a high-level signal (H) as the comparison result signal CO, and when the voltage difference between both ends of the resistor 43 is less than or equal to the reference voltage Vref, the comparator 41 outputs a low-level signal (L) as the comparison result signal CO.

[0061] The drive unit 32 includes a CPU that performs control processing or arithmetic processing related to combustion control, various memories that store and hold data, programs, etc. required in combustion control, etc., and based on the processing result of the CPU, generates a pulse signal having a specified pulse width corresponding to a combustion parameter as an ignition signal S, and based on the ignition signal S, controls the on or off of the IGBT 31. In addition, the drive unit 32 controls the voltage of the control terminal of the IGBT 31 based on the comparison result signal CO so that the primary current I1 does not exceed a specified threshold value. That is, the current detection unit 40 serves as an overcurrent protection circuit. Here, the various memories include: a hard disk drive (HDD), a flash memory, a non-volatile recording medium such as a solid state drive (SSD), etc.

[0062] The operation of the combustion system 2 configured as described above will be described below. Here, the combustion process of the combustion system 2 is controlled by the control device 1 and executed.

[0063] When Figure 1 the combustion process of the combustion system 2 starts, first, the valves 21a to 21d are closed (step S100). Next, dielectric barrier discharge is generated in the dielectric barrier discharge reactor 8 to separate hydrogen from ammonia (step S101). Next, the valve 21b is controlled to open, highly flammable hydrogen is supplied to each igniter 14, and the hydrogen is ignited (step S102). First, control is performed such that the hydrogen ejected from each igniter 14 is ignited by the spark plug 7 to form an ignition flame. Thus, the cold space in the combustion chamber 4 is heated by the ignition flame, and the temperature of the highly non-flammable ammonia can be raised to an easily combustible temperature.

[0064] Next, when the control device 1 determines that the temperature in the combustion chamber 4 has risen to a specified temperature, the control device 1 controls the valve 21a to gradually open (step S103). Thus, the highly non-flammable ammonia is sent into the combustion chamber 4 as a swirling air flow S1 through the swirling blades 23. Here, the ignition flame of each igniter 14 extends to the ammonia to form a premixed flame, and the flame is ejected from the outlet 24. That is, the ammonia supplied to the combustion chamber 4 is ignited by the burning hydrogen (step S104).

[0065] Next, when the ammonia burns, the control device 1 detects the ion current value and based on the detected ion current value, controls the valve 21b to close (step S105). That is, when the control device 1 determines that the highly non-flammable ammonia has reached the optimal combustion state based on the ion current value, the supply of hydrogen to the combustion chamber 4 is stopped. Here, the combustion of ammonia can continue stably.

[0066] In addition, below, the changes in the flow rates of the hydrogen ejected from the Figure 1 igniter 14 and the ammonia ejected from the Figure 1 swirling blades 23 will be described separately.

[0067] Figure 3 is a time-axis waveform diagram showing the changes in the flow rates of the hydrogen ejected from the Figure 1 igniter 14 and the ammonia ejected from the Figure 1 swirling blades 23 with respect to time t. Figure 3 In, at the start of the combustion process (time t = 0), control is performed such that hydrogen starts to be ejected from each igniter 14 at a flow rate f1, and at the same time, the hydrogen is ignited and burned. Here, the hydrogen ejected from each igniter 14 is ignited by the spark plug 7 to form an ignition flame. And control is performed such that the flow rate f of the hydrogen gradually decreases to zero when the ammonia reaches a stable combustion state.

[0068] When the hydrogen starts to burn and the temperature in the combustion chamber 4 rises to a specified temperature (time t = t1), ammonia is ejected from the swivel vane 23 into the combustion chamber 4 in such a way that the flow rate f of ammonia gradually increases. Here, the ignition flame of each igniter 14 extends to the ammonia to form a premixed flame, and the flame is ejected from the outlet 24. When it is judged that the combustion state of the ammonia is in a stable state (time t = t2), control is carried out in such a way that the flow rate f of hydrogen becomes zero, and at the same time the flow rate f of ammonia becomes a flow rate f2 that is greater than the initial flow rate f1 of hydrogen.

[0069] With this configuration, first, highly flammable hydrogen is burned, and after a stable flame is formed in the circumferential direction, the efficiency of the flame extension to highly non-flammable ammonia is increased. As a result, the combustion of the ammonia can be made more stable. Therefore, since the combustion of the ammonia can be made more stable, a flame based on highly non-flammable ammonia can be formed and the ammonia can be burned more stably. Here, the effect of "forming a flame based on ammonia and burning the ammonia stably" includes the effect of reducing combustion fluctuations, where the combustion fluctuations refer to the state of changing the combustion state of the fuel. Furthermore, it also includes the effect of reducing combustion vibrations, where the combustion vibrations refer to the phenomenon in which the pulsation of the combustion gas pressure caused by intermittent combustion causes the entire device to vibrate.

[0070] According to the combustion method of the above-described embodiment, first, hydrogen is burned to heat the combustion chamber to a certain extent, and then non-flammable ammonia is supplied and used to extend the flame from the burning hydrogen to the supplied ammonia. Therefore, the ammonia can be efficiently preliminarily ignited, and the ammonia can continue to burn stably even after ignition.

[0071] Embodiment 2

[0072] In the above-described embodiment, first, the inside of the combustion chamber 4 is heated to a certain extent by burning hydrogen, then non-flammable ammonia is supplied, and the flame is extended from the burning hydrogen to the supplied ammonia. As a result, highly non-flammable ammonia can be efficiently guided to the optimal combustion state. In contrast, the feature of this embodiment is that the destination of the flame extension from the burning hydrogen is set to a mixed gas of ammonia and hydrogen. With this configuration, highly non-flammable ammonia can be further efficiently guided to the optimal combustion state.

[0073] Figure 4 It is a partial cross-sectional side view of the combustion system 2A according to Embodiment 2 of the present invention and a block diagram of the constituent components around it. Compared with Figure 1 the combustion system 2 Figure 4The combustion system 2A has a control device 1A to replace the control device 1, and is characterized by further comprising: a mixer 10 for mixing the hydrogen and ammonia separated and generated by the reformer 13, a valve 21e for adjusting the supply amount of the mixed gas from the mixer 10 to the combustion chamber, and a valve 21f for adjusting the supply amount of hydrogen from the fuel tank 12c to the mixer 10. In addition, compared with the control device 1 of Figure 1 it, the difference is that Figure 4 the control device 1A of it adjusts the mixing amount of ammonia and hydrogen in the mixer 10 by further controlling the opening and closing of the valves 21e and 21f.

[0074] The operation of the combustion system 2A of the embodiment 2 configured as described above will be described below. Here, the combustion process of the combustion system 2A is executed by the control of the control device 1A.

[0075] When Figure 4 the combustion process of the combustion system 2A starts, first, the valves 21a to 21f are controlled to be closed (step S200). Then, in the dielectric barrier discharge reactor 8, dielectric barrier discharge is generated to separate and generate hydrogen from ammonia (step S201). Then, when the valve 21b is controlled to be opened, highly flammable hydrogen is sent to each igniter 14 to ignite the hydrogen (step S202). First, it is controlled such that the hydrogen ejected from each igniter 14 is ignited by the spark plug 7 to form an ignition flame. Thus, the cold space in the combustion chamber 4 is heated by the ignition flame, and the highly non-flammable ammonia can be raised to an easily combustible temperature.

[0076] Next, when the control device 1 determines that the temperature in the combustion chamber 4 has risen to a specified temperature, the control device 1 controls to gradually open each of the valves 21a and 21f (step S203). Thus, the mixing amount of hydrogen and ammonia in the mixer 10 is adjusted to be the mixing amount shown in Figure 6 described later. Then, the control device 1A controls to gradually open the valve 21e (step S204). Thus, the highly non-flammable mixed gas is sent into the combustion chamber 4 as a swirling air current S1 through the swirling blades 23. Here, the ignition flame from each igniter 14 spreads to the mixed gas to form a premixed flame, and the flame is ejected from the outlet 24. That is, the mixed gas supplied to the combustion chamber 4 is ignited by the burning hydrogen (step S205).

[0077] Next, when the mixed gas burns, the control device 1A detects the ion current value and controls the valve 21b to close based on the detected ion current value (step S206). That is, when the control device 1A determines, based on the ion current value, that the highly non-flammable mixed gas has reached the optimal combustion state, the supply of hydrogen to the combustion chamber 4 is stopped, and the valve 21f is closed to adjust the hydrogen mixing amount in the mixer 10 to zero. At this time, since the hydrogen mixing amount in the mixed gas is zero, the fuel being burned is only ammonia. That is, the combustion of ammonia can be stably continued.

[0078] In addition, the changes in the flow rates of hydrogen ejected from the Figure 4 igniter 14 and ammonia ejected from the Figure 4 swirl vane 23 will be described separately below.

[0079] Figure 5 is a time-axis waveform diagram showing the changes in the flow rate of the mixed gas ejected from the Figure 4 igniter 14 and the Figure 4 swirl vane 23 with respect to time t. In Figure 5 , at the start of the combustion process (time t = 0), it is controlled such that hydrogen starts to be ejected from each igniter 14 at a flow rate f1, and at the same time, the hydrogen is ignited and burned. Here, the hydrogen ejected from each igniter 14 is ignited by the spark plug 7 to form an ignition flame. And it is controlled such that the flow rate f of hydrogen gradually decreases to zero when the mixed gas reaches a stable combustion state.

[0080] When this hydrogen starts to burn and the temperature in the combustion chamber 4 rises to a specified temperature (time t = tl), the mixed gas is ejected from the swirl vane 23 into the combustion chamber 4 in such a way that the flow rate f of the mixed gas gradually increases. Here, the ignition flame from each igniter 14 spreads to the mixed gas to form a premixed flame, and a flame is ejected from the outlet 24. When it is determined that the combustion state of the mixed gas is in a stable state (time t = t2), it is controlled such that the flow rate f of hydrogen becomes zero, and at the same time, the flow rate f of the mixed gas becomes a flow rate f2 greater than the initial flow rate f1 of hydrogen.

[0081] Figure 6 is a time-axis waveform diagram showing Figure 4 the changes in the mixing amounts of hydrogen and ammonia in the Figure 5 mixer 10 with respect to time, having the same process time axis as Figure 6In terms of the mixing amount of hydrogen and ammonia in the mixer 10, at the start of the combustion treatment (time t = 0), the mixing amount of hydrogen is made greater than that of ammonia. In the initial combustion step I, as time passes, the mixing amount of ammonia increases and the mixing amount of hydrogen decreases. When it is determined that the combustion state of the mixed gas is in a stable state (time t2), it transfers to the next stable combustion step S. Here, the mixing amount of hydrogen in the mixed gas becomes zero, and only ammonia is ejected from the swirl blade 23.

[0082] According to the combustion method of the above embodiment, first, after burning hydrogen to raise the temperature of the combustion chamber to a certain level, a mixed gas of ammonia and hydrogen is supplied, and the combustion extends from the burning hydrogen to the supplied mixed gas. Therefore, compared with Embodiment 1, initial ignition can be efficiently performed with ammonia, and the combustion of ammonia can be stably continued even after ignition.

[0083] In the above embodiment, although ammonia is used as the non-flammable fuel for description, the present invention is not limited thereto. For example, ammonia compounds or other non-flammable fuels can also be used as the non-flammable fuel. Furthermore, other substances such as carbon-based compounds can be mixed with them as the main raw materials. That is, the present invention includes: a combustion chamber in which the input fuel burns internally, a swirl blade provided in the combustion chamber and sending the first fuel into the combustion chamber as a swirling flow, a reformer that reforms the first fuel by dielectric barrier discharge to generate a second fuel with higher flammability than the first fuel, an igniter that ejects the second fuel with higher flammability than the first fuel into the combustion chamber, a spark plug that ignites the igniter, and a control device that controls the ignition operation of the spark plug. And the control device is also applicable to a combustion system that controls the dielectric barrier discharge in the reformer.

[0084] In addition, in the above embodiment, although a CPU that executes control processing or arithmetic processing related to combustion control held in various memories, data, programs, etc. required for combustion control, and the drive unit 32 controls the on or off of the IGBT 31 are used, the present invention is not limited thereto. For example, the drive unit 32 can also be configured to control the on or off of the IGBT 31 based on at least one of the voltage of the battery 6 and the voltage between the primary coil L1 and the IGBT 31 as a switching element. Furthermore, even in this case, the same operational effects as those of the present embodiment can be obtained. Moreover, compared with the present embodiment, since the voltage between the two ends of the secondary coil L2 becomes a value obtained by multiplying the voltage between the two ends of the primary coil L1 by the turns ratio, the value of the voltage between the two ends of the secondary coil L2 can be easily grasped.

[0085] Furthermore, in the above-described embodiment, although energy is directly supplied from the secondary coil L2 to the reformer 13 and the spark plug 7, the present invention is not limited thereto. For example, a Zener diode or a resistor may be connected between the secondary coil L2 and the discharge electrode 7a of the spark plug 7, or a Zener diode or a resistor may be connected between the secondary coil L2 and the dielectric barrier discharge reactor 8. Even in such a case, the same effect as that of the present embodiment can be obtained. Further, compared with the present embodiment, the energy supplied from the secondary coil L2 to the reformer 13 and the spark plug 7 can be adjusted.

[0086] In addition, further in the above-described embodiment, although the control device 1 stops the supply of hydrogen when it determines that ammonia has reached the optimal combustion state based on the combustion state, the present invention is not limited thereto. For example, the control device 1 may also adjust the supply amount of hydrogen based on the combustion state of ammonia. In this case, compared with the above-described embodiment, since the supply amount of hydrogen can be adjusted quickly according to the combustion state of ammonia, the combustion of ammonia can be continued more efficiently and stably.

[0087] Although the embodiments of the present invention have been described, the above-described embodiments are merely examples and do not limit the scope of the present invention. These novel embodiments can be implemented in various other embodiments, and various omissions, substitutions, and changes can be made without departing from the gist of the present invention. These embodiments and their modifications are included in the scope and gist of the present invention, and also included in the scope of the present invention described in the claims and their equivalents.

[0088] Description of Reference Numerals

[0089] 1, 1A Control device

[0090] 2, 2A Combustion system

[0091] 4 Combustion chamber

[0092] 5 Ignition coil

[0093] 6 Battery

[0094] 7 Spark plug

[0095] 8 Dielectric barrier discharge reactor

[0096] 10 Mixer

[0097] 11 Ignition system

[0098] 13 Reformer

[0099] 14 Igniter

[0100] 18 Bottom

[0101] 20 Cover

[0102] Valves 21a to 21f

[0103] Inlet 22

[0104] Swivel vane 23

[0105] Outlet 24

Claims

1. A method for burning ammonia in a combustion chamber, which comprises: a step of separating and generating hydrogen from ammonia; a step of supplying the hydrogen separated and generated above to the combustion chamber above; a step of igniting and discharging the hydrogen supplied to the combustion chamber above and burning the hydrogen; a step of igniting the ammonia in the combustion chamber above from the burned hydrogen above; a step of detecting combustion state information indicating the combustion state of the ammonia above; and a step of adjusting the supply amount of the hydrogen above to the combustion chamber above based on the detected combustion state information above.

2. The method for burning ammonia according to claim 1, wherein, it further comprises: a step of supplying the ammonia above to the combustion chamber above.

3. The method for burning ammonia according to claim 2, wherein, when the temperature in the combustion chamber above becomes a specified temperature, the ammonia above is supplied to the combustion chamber above.

4. The method for burning ammonia according to any one of claims 1 to 3, wherein, the combustion state information is information related to the output of a turbine, and the turbine uses an ion current based on ions generated by the combustion of the ammonia above or the energy brought by the combustion of the ammonia above.

5. The method for burning ammonia according to any one of claims 1 to 3, wherein, in the step of separating and generating hydrogen from ammonia above, ammonia is reformed by dielectric barrier discharge to separate and generate hydrogen.

6. An ammonia combustion system for burning the input ammonia in a combustion chamber, which comprises: a first pipe for supplying the ammonia above to the combustion chamber above; a first valve provided separately in the first pipe above; a reformer for separating and generating hydrogen from the ammonia above; a second pipe for supplying the hydrogen separated and generated above to the combustion chamber above; a second valve provided separately in the second pipe above; a spark plug for igniting and discharging the hydrogen supplied to the combustion chamber above and burning the hydrogen; a control unit for controlling the opening and closing of the first valve and the second valve above and the ignition and discharge of the spark plug above; a combustion state detection unit for detecting combustion state information indicating the combustion state of ammonia in the combustion chamber above, and the control unit controls in such a way that the supply amount of the hydrogen above to the combustion chamber above is adjusted based on the combustion state information detected by the combustion state detection unit above.

7. The ammonia combustion system according to claim 6, wherein, the control unit first opens the second valve, starts the above ignition and discharge to burn the hydrogen, and controls to open the first valve after the hydrogen burns.

8. The ammonia combustion system according to claim 6 or 7, wherein, it further comprises: a temperature sensor for detecting the temperature in the combustion chamber above, and the control unit raises the temperature to a specified temperature based on the temperature in the combustion chamber above detected by the temperature sensor above.

9. The ammonia combustion system according to claim 6 or 7, wherein, the combustion state information is information related to the output of a turbine, and the turbine uses an ion current based on ions generated by the combustion of the ammonia above or the energy brought by the combustion of the ammonia above.

10. The ammonia combustion system according to claim 6 or 7, wherein, The above control unit reforms ammonia by controlling dielectric barrier discharge in the reformer to separate and generate hydrogen.

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