Fuel combustion device

Abstract

The fuel combustion device (2) of the present invention comprises: a combustion tube (4); a fuel injector (6) for delivering a mixed gas fuel into the combustion tube (4) as a swirling airflow; an igniter (10) having an ignition section (32) in the combustion tube (4); an ion detector (12) having a detection section (40) in the combustion tube (4); and a controller (14) capable of adjusting the fuel mixing ratio according to the detection result of the ion detector (12). Preferably, the fuel is ammonia. Preferably, the detection section (40) is located near the ignition section (32).

Description

Technical Field

[0001] The present invention relates to a fuel combustion device, and more particularly to a combustion device for flame-retardant fuels such as ammonia. Background Art

[0002] As the demand for reducing carbon dioxide emissions increases, ammonia is expected to replace carbon-based fuels. Since ammonia does not contain carbon, it does not emit carbon dioxide even when burned. Ammonia is already widely used as a fertilizer, is inexpensive, and can provide a stable supply. The liquefaction pressure of ammonia is equal to that of LPG, and it can be stored as a liquid at room temperature. Ammonia has many advantages as an alternative fuel to carbon-based fuels.

[0003] On the other hand, ammonia is flame retardant. While the ignition energy of carbon-based fuels is about 80mJ to 120mJ, ammonia requires about 400mJ to 600mJ of ignition energy. In addition, the laminar combustion velocity of ammonia is about 7 times slower than that of carbon-based fuels. Japanese Patent Laid-Open No. 2010-159705 reports a study on an internal combustion engine using this flame retardant ammonia as fuel.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-159705 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, when burning a flame retardant fuel such as ammonia fuel, there are more problems such as difficulty in initial ignition and difficulty in stabilizing combustion compared to the combustion of carbon-based fuels that are currently widely used. In particular, in order to make combustion devices using flame retardant fuels practical in various fields, continuous stable combustion has become an important issue.

[0009] An object of the present invention is to provide a combustion device capable of stably continuing the combustion of a flame retardant fuel.

[0010] Technical means of solving problems

[0011] The fuel combustion device of the present invention comprises: a combustion tube; a fuel injector, which delivers the mixed gas fuel into the combustion tube as a swirling airflow; an igniter, which has an ignition part in the combustion tube; an ion detector, which has a detection part in the combustion tube; and a controller, which can adjust the mixing ratio of the mixed gas fuel according to the detection result of the ion detector.

[0012] Preferably, the fuel is ammonia.

[0013] Preferably, the detection unit is located near the ignition unit. The detection unit may be common to the ignition unit.

[0014] Preferably, the ignition unit includes a discharge electrode and a first ground electrode, the detection unit includes an application electrode and a second ground electrode, and the first ground electrode and the second ground electrode are common.

[0015] Preferably, the ignition portion is located in a region of the combustion tube where the mixed gas fuel accumulates.

[0016] Preferably, the combustion tube includes a cylindrical main body and a lower cover covering an end of the main body, the lower cover is provided with an inlet for feeding the mixed gas fuel, and the ignition unit and the detection unit are arranged on the lower cover.

[0017] Preferably, the detection portion is disposed on the lower cover portion and the main body portion.

[0018] Preferably, the inlet is annular, and the ignition unit and the detection unit are arranged in a region of the lower cover portion surrounded by the inlet.

[0019] The inlet may be circular, and the ignition unit and the detection unit may be arranged around the inlet on the lower cover.

[0020] There are one or more ignition parts, and at least one of the ignition parts is located in a region of the combustion tube where no mixed gas fuel is retained.

[0021] Preferably, the ignition portion is disposed on the lower cover portion and the main body portion.

[0022] The fuel combustion method of the present invention comprises a combustion step for continuously burning the fuel. In the combustion step, a mixed gas fuel containing the fuel is fed into a combustion tube as a swirling airflow, the mixed gas fuel is ignited, ions generated by the combustion are detected, and the mixing ratio of the fuel is adjusted according to the detection result.

[0023] Preferably, the combustion method further comprises the following steps: before the combustion step, measuring the correlation between the parameter representing the combustion state of the fuel and the ion detection result, setting a reference range of the ion detection result. In adjusting the mixing ratio of the fuel, the ion detection result is adjusted so as to fall within the reference range.

[0024] Preferably, the parameter representing the combustion state of the fuel includes an amount of oxide emissions during combustion.

[0025] Effects of the Invention

[0026] The fuel combustion device of the present invention is equipped with an ion current detector in the combustion tube, so it is possible to grasp the combustion state of the mixed gas fuel introduced into the combustion tube. In addition, since the device is also equipped with a controller for adjusting the air-fuel ratio of the mixed gas fuel, it is possible to perform appropriate air-fuel ratio control based on the grasped combustion state.

[0027] In this combustion device, since the mixed gas fuel is fed into the combustion tube as a swirling airflow, a "mixed gas retention area" is generated in the combustion tube where the flow is slower than the mainstream of the swirling airflow and becomes spiral. When an igniter and an ion detector are arranged in this retention area, in this combustion device, the combustion state of the area where energy is effectively supplied is reflected in the ion current, so the state of the flame kernel can be grasped. In addition, since the device is equipped with a controller for adjusting the air-fuel ratio of the mixed gas fuel, air-fuel ratio control based on the state of the flame kernel can be achieved.

[0028] In addition, when an igniter and an ion detector are arranged in a region away from the stagnation region, in the combustion device, since the combustion state in the region with a relatively high-speed flow is reflected in the ion current, the stable state of combustion can be grasped. In addition, since the device is equipped with a controller for adjusting the air-fuel ratio of the mixed gas fuel, air-fuel ratio control that helps stabilize combustion can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a conceptual diagram showing a combustion device according to one embodiment of the present invention.

[0030] Figure 2 Observed from above Figure 1 Diagram of a portion of a combustion device.

[0031] Figure 3 Yes means Figure 1 Connection diagram of a part of a combustion device.

[0032] Figure 4 Yes means Figure 1 A circuit diagram of an example of an ion detection circuit of a combustion device.

[0033] Figure 5 It means in Figure 1 A graph showing the relationship between the mixture ratio, ion current, and oxide emission when the fuel is burned in a combustion device.

[0034] Figure 6 It means in Figure 1 A graph showing the relationship between the flow rate of fuel and the ion current when the fuel is burned in a combustion device.

[0035] Figure 7This is a conceptual diagram showing a combustion device according to another embodiment of the present invention.

[0036] Figure 8 This is a diagram showing a part of a combustion device according to still another embodiment of the present invention as viewed from above. DETAILED DESCRIPTION

[0037] Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to appropriate drawings.

[0038] Figure 1 1 is a conceptual diagram showing a fuel combustion device 2 according to an embodiment of the present invention. In the figure, a portion of the device 2 is shown in cross section. The combustion device 2 includes a combustion cylinder 4, a fuel injector 6, a fuel mixer 8, an igniter 10, an ion detector 12, and a controller 14. In this specification, Figure 1 The direction indicated by the arrow X is the downward direction of the combustion device 2, and the opposite direction is the upward direction. The direction in which the fuel injector 6 is located is downward.

[0039] The combustion tube 4 is in a cylindrical shape. In this embodiment, the combustion tube 4 is in a cylindrical shape. Figure 1 , a cross section of the combustion tube 4 is shown. The combustion tube 4 has a main body 16, a lower cover 18, and an upper cover 20. The main body 16 forms a side surface of the combustion tube 4. The main body 16 extends in the up-down direction. The lower cover 18 covers the lower end of the main body 16. An inlet 22 is provided on the lower cover 18. A mixed gas containing fuel (mixed gas fuel) is fed from the inlet 22. Figure 2 This is a view of the lower cover 18 viewed from above. As shown in the figure, in this embodiment, the inlet 22 is annular. The upper cover 20 covers the upper end of the main body 16. An output port 23 for flame ejection is provided in the center of the upper cover 20. In this embodiment, the material of the combustion tube 4 is heat-resistant glass.

[0040] like Figure 1 As shown, the fuel injector 6 is located below the lower cover 18 of the combustion tube 4. The fuel injector 6 includes a shell 24 and a swirler 26. When viewed from below, the shell 24 is annular. The inside of the shell 24 is hollow. The swirler 26 is located inside the shell 24. The swirler 26 is located below the injection port 22. Figure 2 In the figure, the swirler 26 located at the lower side can be seen through the inlet 22. The swirler 26 includes a plurality of inclined blades. The mixed gas fuel fed into the housing 24 passes through the swirler 26, thereby becoming an airflow (swirl airflow) accompanied by a rotating vortex (spiral flow). The mixed gas fuel is fed into the combustion tube 4 as a swirling airflow. The material of the swirler 26 is typically steel.

[0041] Although not shown, the fuel injector 6 may further include a driving unit for rotating the swirler 26. The swirler 26 may be rotated to feed the mixed gas fuel into the combustion cylinder 4 as a swirling airflow.

[0042] The fuel mixer 8 includes a fuel tank 28 and a valve 30. In this embodiment, the fuel mixer 8 includes a first valve 30a and a second valve 30b. The fuel tank 28 stores a flame-retardant fuel that serves as the main fuel of the combustion device 2. In this embodiment, the fuel tank 28 stores liquefied ammonia. The liquefied ammonia is gasified and sent to the fuel injector 6. The fuel tank 28 is connected to the first valve 30a. The first valve 30a adjusts the amount of fuel in the mixed gas fuel. The second valve 30b adjusts the amount of air in the mixed gas fuel.

[0043] The fuel mixer 8 may also include a fuel tank storing a secondary fuel and a third valve connected thereto. At this time, two fuels and air are mixed in the fuel mixer 8. The secondary fuel has higher combustibility than the main fuel. That is, the ignition energy of the secondary fuel is smaller than the ignition energy of the main fuel, and the laminar combustion speed of the secondary fuel is greater than the laminar combustion speed of the main fuel. By mixing the secondary fuel with high combustibility, the ignition of the mixed gas fuel becomes easier. Methane can be cited as a typical secondary fuel. The combustion device 2 may also include three or more fuel tanks.

[0044] Figure 3 1 is a connection diagram showing the connection among the igniter 10 , the ion detector 12 , and the controller 14 .

[0045] The igniter 10 ignites the mixed gas fuel. Figure 3 As shown in FIG. 1 , the igniter 10 includes an ignition unit 32 and a voltage generating unit. Figure 1 The ignition section 32 is shown in FIG. Figure 1 Two ignition sections 32 are shown.

[0046] The ignition portion 32 is disposed in the “region where the mixed gas fuel accumulates”. Figure 1 The arrows in FIG. 2 indicate the flow of the swirling airflow of the mixed gas fuel. The mainstream of the swirling airflow flowing in from the inlet 22 ( Figure 2 The thick dotted line (shown in FIG. 1 ) swirls while expanding along the inner circumference of the combustion tube 4 and moving upward. The gas pressure in the portion where the main flow flows becomes low, so the mixed gas fuel in the central portion of the combustion tube 4 is dragged by this flow. A spiral flow ( Figure 2). The region where the spiral flow is generated is the "region where the mixed gas fuel is retained (retention region)". In this retention region, an airflow with a speed slower than the mainstream of the swirling airflow continuously flows in. In this portion, the mixed gas fuel becomes spiral while flowing from bottom to top as a whole at a speed slower than the mainstream of the swirling airflow. In the retention region, the mixed gas fuel becomes a spiral flow, so the mixed gas fuel is repeatedly guided to the ignition part 32. The mixed gas fuel repeatedly passes near the ignition part 32.

[0047] As a typical retention area, the vicinity 39a of the area 38 of the lower cover portion 18 surrounded by the annular inlet 22 can be cited. Similarly, the vicinity 39b outside the inlet 22 is also a retention area. Figure 1 As shown, there is also a stagnation area at the inner side 39c of the main flow in the center of the vertical direction of the combustion tube 4. For example, these stagnation areas can be investigated by injecting colored smoke into the combustion tube 4 at the same speed as the mixed gas fuel. The stagnation areas can also be investigated in simulation.

[0048] In this embodiment, the ignition part 32 is located in the lower cover part 18. The ignition part 32 is located inside the combustion tube 4. A plurality of ignition parts 32 are arranged in a region 38 of the lower cover part 18 surrounded by the annular inlet 22. These ignition parts 32 are located in the retention area. Figure 2 As shown, in this embodiment, the area 38 surrounded by the inlet 22 is circular. Figure 2 Although it is hidden by the ion detector 12 and cannot be seen, multiple ignition parts 32 are arranged on the concentric circles of the area 38 on the lower side of these ion detectors 12. These ignition parts 32 are arranged in a manner to form a circle on the concentric circles of the area 38 surrounded by the inlet 22. The ignition parts 32 can also be arranged in a manner to form multiple circles on the concentric circles of the area 38. The positions where the ignition parts 32 are arranged are not limited to the concentric circles of the area 38 surrounded by the inlet 22. Multiple ignition parts 32 can also be arranged in a spiral shape in the area 38. The number of ignition parts 32 can also be one.

[0049] The lower cover 18 where the ignition part 32 is located is located on the upstream side of the mixed gas fuel flow. In the combustion device 2, in order to fully burn the fuel, the ignition part 32 is located on the upstream side of the mixed gas fuel flow. The distance between the position where the ignition part 32 ignites (the top of the ignition part 32) and the inlet 22 in the vertical direction is less than 50% of the length of the main body 16 in the vertical direction, and more preferably less than 25%.

[0050] like Figure 1As shown, in this embodiment, the ignition portion 32 includes a discharge electrode 34 and a first ground electrode 36. The discharge electrode 34 and the first ground electrode 36 are hook-shaped formed by bending a rod. The discharge electrode 34 and the first ground electrode 36 protrude inward from the lower cover portion 18. Although not shown in the figure, a grounding terminal is provided on the lower cover portion 18. The first ground electrode 36 is grounded by contacting the terminal. The discharge electrode 34 is electrically connected to the voltage generating portion. A high voltage is applied to the discharge electrode 34 from the voltage generating portion. As a result, a spark is generated between the top end of the discharge electrode 34 and the top end of the first ground electrode 36. As a result, the mixed gas fuel is ignited. The ignition portion 32 is a spark plug. The ignition portion 32 may not be a spark plug. The ignition portion 32 may be composed of a plasma jet spark plug.

[0051] The voltage generating unit generates a high voltage based on a signal from the controller 14. Although not shown, the voltage generating unit has a primary coil and a secondary coil built in. By repeatedly interrupting and conducting the current of the primary coil, a high voltage is intermittently generated on the secondary coil side.

[0052] The ion detector 12 detects ions in the combustion tube 4. Figure 3 As shown in FIG. 1 , the ion detector 12 includes a detection unit 40 and a detection circuit unit. Figure 1 as well as Figure 2 The detection part 40 is shown in FIG. In this embodiment, the detection part 40 includes a hook-shaped detection part 40a and a loop-shaped detection part 40b.

[0053] like Figure 1 As shown in FIG. 2 , the hook-shaped detection portion 40a is located at the lower cover portion 18. Figure 2 As shown, a plurality of detection parts 40a are arranged on concentric circles of the area 38 surrounded by the inlet 22. Each hook-shaped detection part 40a has an application electrode 42 and a second ground electrode 44. The application electrode 42 and the second ground electrode 44 of the hook-shaped detection part 40a are hook-shaped by bending a rod. The application electrode 42 and the second ground electrode 44 protrude from the lower cover part 18 to the inside. Figure 1 In the embodiment of FIG. 4 , the second ground electrode 44 is common to the first ground electrode 36. The second ground electrode 44 may not be common to the first ground electrode 36. The applying electrode 42 is electrically connected to the detection circuit unit.

[0054] Although not shown, the applying electrode 42 may be common to the discharge electrode 34 of the ignition section 32. The applying electrode 42 may be common to the discharge electrode 34, and the second ground electrode 44 may be common to the first ground electrode 36. That is, the detection section 40a and the ignition section 32 may be common. Furthermore, a circuit in which the detection circuit section and the voltage generating section are integrated may be used. In this case, each igniter performs ignition and ion detection by discharge.

[0055] The ring-shaped detection portion 40 b is located in the main body 16 . Figure 1 Two annular detection parts 40b are shown. Each annular detection part 40b has an application electrode 42 and a second grounding electrode 44. The application electrode 42 and the second grounding electrode 44 are annular. The application electrode 42 and the second grounding electrode 44 are attached to the inner surface of the cylindrical main body 16. The application electrode 42 is electrically connected to the detection circuit part. Although not shown in the figure, a grounding terminal is provided on the main body 16. The second grounding electrode 44 is grounded by contacting the terminal.

[0056] Figure 4 FIG. 1 shows an example of a circuit of the ion detector 12. Figure 4 As shown, the detection circuit unit is composed of a power supply E, a resistor R and a voltage measuring unit. The power supply E applies a voltage to the applying electrode 42 of the detection unit 40 through the resistor R. In this embodiment, a negative voltage is applied. For example, the voltage of the power supply E is -200V. When ions exist around the detection unit 40, the ions are attracted by the applying electrode 42 and current (ion current) flows through them. The more ions there are, the greater the ion current that flows. The voltage measuring unit detects and amplifies the potential difference generated by the ion current at both ends of the resistor R. The voltage measuring unit detects a voltage proportional to the ion current. The ion current is obtained based on the voltage. In the ion detector 12, the ion current is obtained as the detection result of the ions.

[0057] The power source E may also apply a positive voltage to the applying electrode 42. For example, the voltage of the power source E may be 200 V. When electrons generated together with ions exist around the detection unit 40, the electrons are attracted by the applying electrode 42 and an ion current flows. The more ions there are, that is, the more electrons there are, the greater the ion current flows. The ion current is measured by measuring the voltage across the resistor R.

[0058] Ions are heavier than electrons. Ions are more difficult to move than electrons. When a negative voltage is applied to the application electrode 42, ions near the application electrode 42 are attracted. This method is suitable for detecting the amount of ions near the application electrode 42. Since electrons are easy to move, electrons are attracted from a wider range when a positive voltage is applied to the application electrode 42 than when a negative voltage is applied. This method is suitable for detecting the amount of ions in a larger range around the application electrode 42. Which voltage, positive or negative, to apply to the application electrode 42 is appropriately selected according to the purpose or design concept of the combustion device.

[0059] The configuration of the detection circuit unit is not limited to Figure 4 The voltage measuring unit and the resistor may be provided in parallel with the power supply between the power supply and the applying electrode 42. A capacitor and a charging circuit for charging the capacitor may be provided instead. Figure 4The power source E of the discharge electrode 34 is provided. In this configuration, a current flows between the capacitor and the application electrode 42. In addition, the detection circuit unit and the voltage generating unit of the igniter 10 may be configured as an integral unit. For example, when the voltage generating unit applies a high voltage to the discharge electrode 34, the voltage generating unit may charge the capacitor of the detection circuit unit at the same time.

[0060] The controller 14 is connected to the igniter 10 , the ion detector 12 , and the fuel mixer 8 . Figure 1 The symbol P in FIG. 1 represents a connection line with the igniter 10, and the symbol I represents a connection line with the ion detector 12. Figure 3 As shown, the controller 14 has an ion analysis unit, a valve control unit, and an ignition control unit. The detection results from all ion detectors 12 are analyzed by the ion analysis unit. The valve control unit controls the valve 30 of the fuel mixer 8 based on the results. This changes the mixing ratio of the fuel. The ignition control unit controls the ignition timing of each igniter 10 based on the analysis results of the ion analysis unit. Adjust the ignition timing of the igniter 10.

[0061] The controller 14 is typically implemented by a microcomputer. In this case, Figure 3 The circuits for the ion analysis unit, valve control unit, and ignition control unit do not exist separately. These functions are realized by a microcomputer and software. The controller 14 may also have dedicated circuits for the ion analysis unit, valve control unit, and ignition control unit.

[0062] In use Figure 1-4 In the combustion of the device 2 shown, at the start of combustion, the first valve 30a and the second valve 30b are opened by the controller 14, and the mixed gas of fuel and air is fed into the fuel injector 6 at a specified flow rate. In this embodiment, the mixed gas fuel of ammonia and air is fed to the fuel injector 6. The mixed gas fuel passes through the swirler 26 of the fuel injector 6 and is fed into the combustion tube 4 as a swirling airflow. The igniter 10 is driven by the controller 14 to ignite the mixed gas fuel. At this time, a plurality of igniters 10 are driven simultaneously. As a result, the mixed gas fuel burns. The ion detector 12 detects ions in the combustion tube 4 generated by the combustion as an ion current.

[0063] The combustion method of the present invention comprises:

[0064] (1) a reference range setting step of setting a reference range of the ion current; and

[0065] (2) Combustion step to ensure continuous combustion of fuel

[0066] In step (1), the correlation between the ion current and a parameter representing the combustion state is measured. Figure 5The straight line a represents the relationship between the mixture ratio of fuel (ammonia) and air (air-fuel ratio λ) and the ion current Iz at a predetermined flow rate of the mixed gas fuel (referred to as λ-Iz function). Figure 5 It is shown that the higher the air-fuel ratio λ is, the larger the ion current Iz is. Figure 5 The curve d represents the relationship between the air-fuel ratio λ at this time and the amount of oxides (nitrogen oxides NOx) emitted when the fuel is burned. The amount of nitrogen oxides has a peak at a specific air-fuel ratio λ. Depending on the value of the air-fuel ratio λ at this time, the higher or lower the air-fuel ratio λ, the less the amount of nitrogen oxides. In the step (1), data representing the λ-Iz function is obtained as mapping data. The mapping data is obtained multiple times according to the temperature and pressure in the combustion barrel. In addition, considering the continuity of stable combustion, fuel efficiency and oxide emissions, a reference range of the ion current is set. Figure 5 An example of the reference range is shown in . These map data and the reference range are stored in a memory circuit (not shown) of the controller 14 .

[0067] In the step (2), the mixed gas fuel is continuously sent to the combustion tube 4 while the igniter 10 is driven at a certain time interval. Thus, the mixed gas fuel is continuously burned. The ion detector 12 detects the ions in the combustion tube 4 at this time as an ion current. The controller 14 determines the air-fuel ratio λ based on the detected ion current and the λ-Iz function. The controller 14 adjusts the first valve 30a and the second valve 30b in such a way that the ion current is within the reference range set in the step (1). The air-fuel ratio λ is adjusted in such a way that the ion current is within the reference range set in the step (1).

[0068] In the above embodiment, the λ-Iz function (i.e., straight line a) at a predetermined flow rate of the mixed gas fuel is used to determine the air-fuel ratio λ. In practice, the flow rate of the mixed gas fuel can vary. As another embodiment of the combustion method, a correction process based on the flow rate variation can also be implemented so that the air-fuel ratio λ can be determined more accurately. The method will be described below.

[0069] Figure 6 The relationship between the flow velocity v and the ion current Iz at the reference air-fuel ratio λ (called v-Iz function) is shown as Figure 6 As shown, it shows that the larger the flow velocity v is, the larger the ion current Iz is. In this embodiment, in the step (1), the v-Iz function is also obtained as mapping data. Figure 5 , only the v-Iz function at the reference air-fuel ratio λ is shown, but the map data is acquired for a plurality of air-fuel ratios λ. These map data are stored in the memory circuit of the controller 14.

[0070] Figure 5The dotted line b represents the λ-Iz function in the high-speed state where the flow velocity is increased. The dotted line c represents the λ-Iz function in the low-speed state where the flow velocity is decreased. In the above step (1), these data are also acquired as mapping data. These mapping data are stored in the memory circuit of the controller 14. Figure 5 In FIG. 1 , the λ-Iz function at three flow rates is shown, but the λ-Iz function can also be obtained at more flow rates.

[0071] In this embodiment, in determining the air-fuel ratio λ in step (2), the controller 14 determines the flow velocity v using the mapping data of the v-Iz function based on the detection result of the ion detector 12. At this time, the mapping data under the air-fuel ratio λ determined in the process before this process is used. Thus, the controller 14 determines that the combustion state is a high-speed state, for example. At this time, the controller 14 determines that the combustion state is a high-speed state. Figure 5 The air-fuel ratio λ is determined by the λ-Iz function at high speed. Figure 6 When the image data of the air-fuel ratio λ is obtained, the image data of the air-fuel ratio λ is used. The flow velocity v is determined by this. The process is repeated.

[0072] Hereinafter, the effects of the present invention will be described.

[0073] In the fuel combustion device 2 of the present invention, a mixed gas fuel containing fuel is fed into the combustion tube 4 as a swirling airflow. In the mixed gas fuel, a spiral flow is formed, and as a whole, there is a part that flows at a slower speed than the main flow of the swirling airflow. In the combustion device 2, a flame-retardant fuel with a slow laminar combustion speed can be burned.

[0074] The ignition part 32 of the igniter 10 of the combustion device 2 is located in the area where the mixed gas fuel is retained in the combustion tube 4. The spiral mixed gas fuel with a slower speed than the mainstream speed of the swirling airflow continuously flows into the retention area. Therefore, the mixed gas fuel is repeatedly guided to the ignition part 32. The mixed gas fuel repeatedly passes near the ignition part 32. As a result, the ignition part 32 can provide large energy to the mixed gas fuel. In the device 2, even for a fuel with high ignition energy, sufficient energy can be provided for ignition.

[0075] The combustion device 2 is provided with a detection unit 40 of an ion detector 12 in a combustion tube 4. By detecting ions generated by combustion by the detection unit 40, the combustion state of the mixed gas fuel can be grasped. The combustion device 2 is provided with a controller 14 that adjusts the mixing ratio of the fuel according to the detection result, so that appropriate air-fuel ratio control based on the grasped combustion state can be performed. This contributes to the continuation of stable combustion. In the combustion device 2, the combustion of the flame-retardant fuel can be stably continued.

[0076] like Figure 1As shown, it is preferred that there is a detection unit 40 located near the ignition unit 32. The ignition unit 32 is located in the stagnation area. In the detection unit 40 near the ignition unit 32, since the detected ion current reflects the combustion state of the area where energy is effectively supplied, the state of the flame kernel can be grasped. In this device 2, air-fuel ratio control based on the state of the flame kernel and control of the ignition timing of the igniter 60 can be achieved. In this combustion device 2, it is possible to stably and effectively burn a flame-retardant fuel.

[0077] The mixing ratio of the fuel affects the amount of generated oxides. Adjustment of the mixing ratio of the fuel can contribute to the reduction of the generation of oxides. In the combustion device 2, the emission of oxides can be suppressed while the stable combustion of the flame-retardant fuel is continued.

[0078] The combustion method using the device 2 includes the following steps: measuring the correlation between the parameter representing the combustion state of the fuel and the ion current to set a reference range of the ion current. In the step of continuously burning the fuel, the ion current value detected by the ion detector 12 is set to the reference range, so that the appropriate combustion state can be continuously maintained.

[0079] The parameter indicating the combustion state preferably includes the amount of the discharged oxides. Thus, combustion that more effectively suppresses the discharge of oxides can be achieved. In this combustion method, the discharge of oxides can be suppressed while the flame retardant fuel is stably burned.

[0080] When the ignition unit 32 includes the discharge electrode 34 and the first ground electrode 36, and the detection unit 40 includes the application electrode 42 and the second ground electrode 44, the first ground electrode 36 and the second ground electrode 44 are preferably common. This can prevent these ground electrodes from hindering efficient combustion.

[0081] like Figure 1 As shown, it is preferred that there is a detection portion 40 disposed from the lower cover portion 18 side to the opposite side on the inner surface of the main body 16. Thus, the combustion state at a position above the fuel inlet 22 can be detected. This helps to set an appropriate fuel mixing ratio and the ignition timing of the igniter 10. In this combustion device 2, it is possible to stably and effectively burn a flame-retardant fuel while suppressing the discharge of oxides.

[0082] As described above, the ignition portion 32 is preferably disposed in the region 38 of the lower cover portion 18 that is surrounded by the annular inlet 22. The mixed gas fuel flow is retained inside the annular inlet 22. By configuring the ignition portion 32 of the igniter 10 in the region 38, the mixed gas fuel that becomes a spiral flow is repeatedly introduced into the ignition portion 32. The mixed gas fuel repeatedly passes through the vicinity of the ignition portion 32. Therefore, in the device 2, even for a fuel that is difficult to burn, sufficient energy can be provided for ignition. Moreover, these ignition portions 32 are located upstream of the mixed gas fuel flow. Thus, even for a fuel that is difficult to burn, stable ignition and combustion can be achieved.

[0083] As described above, when the area 38 surrounded by the inlet 22 is circular, the ignition portion 32 is preferably disposed on a concentric circle of the area 38. In this way, the mixed gas fuel can be ignited uniformly around the inlet 22. Thus, the mixed gas fuel can be stably ignited.

[0084] Although not shown in the figure, the combustion device 2 may also have a temperature sensor for measuring the temperature in the combustion tube 4. The temperature sensor is connected to the controller 14, and the temperature measurement result is sent to the controller 14. Generally, if the temperature in the combustion tube 4 becomes higher, the fuel is easy to burn. Ammonia also has better combustion properties as the temperature is higher, and the amount of nitrogen oxides NOx emitted is reduced. In the combustion device 2, the controller 14 adjusts the mixing ratio of the fuel based on the temperature measurement result. The controller 14 controls the ignition timing of the igniter 10 based on the temperature measurement result. These contribute to the continuation of stable combustion. In the combustion device 2, stable combustion can be continued.

[0085] Although not shown in the figure, the combustion device 2 may also have a pressure sensor for measuring the pressure in the combustion tube 4. The pressure sensor is connected to the controller 14, and the pressure measurement result is sent to the controller 14. Generally, if the pressure in the combustion tube 4 becomes higher, the fuel is easy to burn. Ammonia also has better combustion properties as the pressure is higher, and the amount of nitrogen oxides NOx emitted is reduced. In the combustion device 2, the controller 14 adjusts the mixing ratio of the fuel based on the pressure measurement result. The controller 14 controls the ignition timing of the igniter 10 based on the pressure measurement result. These contribute to the continuation of stable combustion. In the combustion device 2, stable combustion can be continued.

[0086] Although not shown, the combustion device 2 may also include a drive mechanism for controlling the angle of the blades of the swirler 26. The drive mechanism is connected to the controller 14. The controller 14 controls the angle of the blades through the drive mechanism, thereby adjusting the swirl ratio of the swirling airflow. The controller 14 adjusts the angle of the blades based on the measurement results of the ion current, temperature, and pressure. These contribute to the continuation of stable combustion. In the combustion device 2, stable combustion can be continued.

[0087] Figure 7 1 is a conceptual diagram showing a fuel combustion device 52 according to another embodiment of the present invention. In this figure, a portion of the device 52 is shown in cross section. The combustion device 52 includes a combustion tube 54, a fuel injector 56, a fuel mixer 58, an igniter 60, an ion detector 62, and a controller 64. In this embodiment, the combustion tube 54 is made of steel. The fuel injector 56, the fuel mixer 58, and the controller 64 of the combustion device 52 are similar to the combustion device 54. Figure 1 These devices of the combustion device 2 are the same. Figure 7 The direction indicated by the arrow X is the bottom of the combustion device 52, and the opposite direction is the top.

[0088] The igniter 60 includes an ignition unit 66 and a voltage generating unit. Figure 7 The ignition section 66 is shown in FIG. Figure 7 As shown, in this embodiment, the ignition part 66 is located on the lower cover part 68 and the main body 70. A plurality of ignition parts 66 are located on the lower cover part 68 and the main body 70. The ignition part 66 located on the lower cover part 68 and the main body 70 are Figure 1 The ignition section 32 is also located in the retention area. Among the ignition sections 66 located in the main body 70, there are ignition sections 66 located in an area where the mixed gas fuel is not retained. For example, there are ignition sections 66 located in a place where the mainstream of the swirling airflow flows. In this embodiment, the ignition sections 66 located in the retention area and the ignition sections 66 located in an area away from the retention area are mixed. Although not shown in the figure, the voltage generating section of this embodiment is Figure 3 The voltage generating section is the same.

[0089] The ignition unit 66 located on the lower cover 68 includes a discharge electrode 72 and a first ground electrode 74. The first ground electrode 74 is grounded by contacting the grounded lower cover 68. Figure 1 The discharge electrode 34 is the same.

[0090] The ignition parts 66 located in the main body 70 are arranged from the lower cover part 68 side to the opposite side thereof. Each ignition part 66 includes a discharge electrode 72 and a first ground electrode 74. The discharge electrode 72 and the first ground electrode 74 are hook-shaped formed by bending a rod. The discharge electrode 72 and the first ground electrode 74 of the ignition part 66 located in the main body 70 protrude inward from the inner surface of the main body 70. The first ground electrode 74 is grounded by contacting the grounded main body 70. The discharge electrode 72 is electrically connected to the voltage generating part. A high voltage is applied to the discharge electrode 72 from the voltage generating part. As a result, a spark is generated between the top end of the discharge electrode 72 and the top end of the first ground electrode 74. As a result, the mixed gas fuel is ignited.

[0091] The ion detector 62 includes a detection unit 76 and a detection circuit unit. Figure 7 Indicates the detection unit 76. Figure 7 As shown, the detection part 76 is located at the lower cover part 68 and the main body 70. A plurality of detection parts 76 are located at the lower cover part 68 and the main body 70. In this embodiment, all the detection parts 76 are hook-shaped. The structure of the detection part 76 located at the lower cover part 68 is similar to that of the detection part 76 located at the lower cover part 68. Figure 1 Although not shown in the figure, the detection circuit section of this embodiment is the same as Figure 4 The detection circuit part is the same.

[0092] The detection parts 76 located in the main body 70 are arranged from the lower cover part 68 side to the opposite side. Each detection part 76 has an application electrode 78 and a second ground electrode 80. The application electrode 78 and the second ground electrode 80 are hook-shaped by bending a rod. The application electrode 78 and the second ground electrode 80 located in the main body 70 protrude inward from the inner surface of the main body 70. The detection part 76 is located near the ignition part 66 of the main body 70. Figure 7 In the embodiment, the second ground electrode 80 is common to the first ground electrode 74 of the ignition portion 66 located on the main body 70. The second ground electrode 80 may not be common to the first ground electrode 74. The application electrode 78 is electrically connected to the detection circuit portion.

[0093] In the combustion device 52, the ignition part 66 of the igniter 60 is located not only in the lower cover part 68 but also in the main body 70. These ignition parts 66 are arranged from the lower cover part 68 side to the opposite side. In the combustion device 52, the fuel can be ignited also in the center and the upper part of the main body 70. In the combustion device 52, the fuel can be burned evenly in the entire combustion tube 54. Thus, even for a flame-retardant fuel, stable ignition and combustion can be achieved.

[0094] In the combustion device 52, the detection part 76 of the ion detector 62 is located near the ignition part 66 of the lower cover part 68 and near the ignition part 66 of the main body 70. That is, the detection part 76 is located near the ignition part 66 of the retention area and near the ignition part 66 of the area away from the retention area. In the detection part 76 located near the ignition part 66 of the retention area, the detected ion current reflects the combustion state of the area where energy is effectively supplied, so the state of the flame core can be grasped. In the device 52, air-fuel ratio control based on the state of the flame core and control of the ignition timing of the igniter 60 can be achieved. This contributes to the formation of a stable flame core. In the combustion device 52, stable combustion can be sustained.

[0095] In the detection part 76 located near the ignition part 66 in the area away from the stagnation area, the ion current detected reflects the combustion state in the area where the fuel flows at a relatively high speed, so the stable state of combustion can be grasped. In this device 52, the air-fuel ratio control based on the stable state of combustion and the control of the ignition timing of the igniter 60 can be realized. This contributes to the stabilization of combustion.

[0096] Although not shown, the combustion device 52 may also have a plurality of temperature sensors arranged from the lower cover side to the opposite side in the combustion tube 54. These temperature sensors measure the temperature distribution in the combustion tube 54. In the combustion device 52, the controller 64 controls the ignition timing of each igniter 60 based on the measurement results of these temperatures. According to the location of the ignition part 66, the appropriate ignition timing of the igniter 60 can be achieved. This helps to continue stable combustion. In the combustion device 52, stable combustion can be continued.

[0097] Although not shown, the combustion device 52 may also have a plurality of pressure sensors arranged from the lower cover side to the opposite side in the combustion tube 54. These pressure sensors measure the pressure distribution in the combustion tube 54. In the combustion device 52, the controller 64 controls the ignition timing of each igniter 60 based on the measurement results of these pressures. According to the location of the ignition part 66, the appropriate ignition timing of the igniter 60 can be achieved. This helps to continue stable combustion. In the combustion device 52, stable combustion can be continued.

[0098] Figure 8 This is a view of a lower cover 94 of a fuel combustion device 92 according to another embodiment of the present invention as viewed from above. The combustion device 92 includes the lower cover 94, a fuel injector 96, an igniter, and an ion detector 98. Figure 1 as well as Figure 2 The combustion device 2 is the same.

[0099] like Figure 8 As shown, an inlet 100 is provided on the lower cover portion 94 of the combustion device 92. A mixed gas fuel containing fuel is fed into the inlet 100. In this embodiment, the inlet 100 is circular.

[0100] The fuel injector 96 is located below the lower cover 94 of the combustion tube. The fuel injector 96 includes a swirler 102. Figure 8 In the figure, the swirler 102 located at the lower side can be seen through the inlet 100. The mixed gas fuel passes through the swirler 102 to become a swirling airflow. The mixed gas fuel is fed into the combustion tube as a swirling airflow. The material of the swirler 102 is typically steel.

[0101] Although in Figure 8Although it is blocked by the detection part 104 and cannot be seen, multiple ignition parts are located on the lower side of the detection part 104. Multiple ignition parts are arranged in the lower cover part 94 in a manner surrounding the circular inlet 100. The area around the inlet 100 is a retention area. The spiral mixed gas fuel, which is slower than the mainstream speed of the swirling airflow, flows continuously into the retention area. Therefore, the mixed gas fuel is repeatedly guided to the ignition part. The mixed gas fuel repeatedly passes near the ignition part. Therefore, the ignition part 32 can provide large energy to the mixed gas fuel. In this device 92, even for fuels with high ignition energy, sufficient energy can be provided for ignition.

[0102] In this embodiment, a plurality of ignition parts are arranged on the concentric circles of the circular inlet 100. These ignition parts are arranged in a manner to form a circle on the concentric circles of the inlet 100. In this way, the mixed gas fuel can be ignited uniformly around the inlet 100. Thus, the mixed gas fuel can be stably ignited.

[0103] Although not shown, these igniters may be arranged in a manner to form a plurality of circles on the concentric circles of the inlet 100. These ignition parts may also be arranged in a spiral shape in a manner to surround the periphery of the inlet 100. In this way, the mixed gas fuel can be ignited uniformly around the inlet 100. Thus, the mixed gas fuel can be stably ignited.

[0104] The detection part 104 of the ion detector 98 is arranged on the lower cover part 94. The detection part 104 is hook-shaped. Figure 8 As shown, the detection unit 104 is arranged on a concentric circle of the circular inlet 100. The detection unit 104 is located near the ignition unit. In the detection unit 104, the ion current detected reflects the combustion state of the area where energy is effectively supplied, so the state of the flame kernel can be grasped. In the device 92, the air-fuel ratio control based on the state of the flame kernel and the control of the ignition timing of the igniter can be realized.

[0105] In the combustion device shown in the above embodiment, fuel is continuously sent to the combustion device. The combustion device can also be applied to internal combustion engines such as automobiles. In this case, the introduction of fuel into the combustion cylinder and the ignition of the fuel are repeated as a cycle.

[0106] As described above, according to the present invention, a combustion device capable of stably continuing the combustion of a flame retardant fuel can be realized. As can be seen from this, the advantages of the present invention are very obvious.

[0107] Possibility of Industrial Application

[0108] The fuel combustion device described above is used in various equipment.

[0109] Explanation of symbols

[0110] 2, 52, 92… Combustion device

[0111] 4.54…Combustion tube

[0112] 6, 56…Fuel injector

[0113] 8, 58…Fuel mixer

[0114] 10, 60…Ignition

[0115] 12, 62, 98…Ion detector

[0116] 14, 64…Controller

[0117] 16, 70…Main body

[0118] 18, 68, 94…Lower cover

[0119] 20…Bottom

[0120] 22, 100…Inlet

[0121] 24…Housing

[0122] 26, 102…cyclone

[0123] 28…Fuel tank

[0124] 30…Valve

[0125] 30a…First valve

[0126] 30b…Second valve

[0127] 32, 66…Ignition

[0128] 34, 72…Discharge electrode

[0129] 36, 74…first ground electrode

[0130] 38…Area surrounded by the inlet

[0131] 40, 76…Detection Department

[0132] 40a…Hook-type detection unit

[0133] 40b…Ring-shaped detection unit

[0134] 42, 78, 104...Apply electrodes

[0135] 44, 80 ...second ground electrode.

Claims

1. A fuel combustion device, characterized in that: have: Combustion tube; A fuel injector, which delivers the mixed gas fuel into the combustion tube as a swirling airflow; an igniter having an ignition portion in the combustion tube; an ion detector including a detection unit in the combustion cylinder; and a controller capable of adjusting the mixing ratio of the mixed gas fuel according to the detection result of the ion detector, The combustion tube includes a cylindrical main body and a lower cover covering an end of the main body. The lower cover is provided with an inlet for feeding the mixed gas fuel. The ignition part is arranged on the lower cover part and the main body part. The detection unit is common to the ignition unit, At least one of the ignition parts is located in a region of the combustion tube where the mixed gas and fuel accumulate.

2. The combustion device according to claim 1, characterized in that: The fuel is ammonia.

3. The combustion device according to claim 1 or 2, characterized in that: The ignition unit includes a discharge electrode and a first ground electrode, the detection unit includes an application electrode and a second ground electrode, and the first ground electrode and the second ground electrode are common.

4. The combustion device according to claim 1 or 2, characterized in that: The detection unit is disposed on the lower cover.

5. The combustion device according to claim 1 or 2, characterized in that: The detection unit is disposed on the lower cover and the main body.

6. The combustion device according to claim 1 or 2, characterized in that: The input port is annular. At least one of the ignition unit and the detection unit is disposed in a region of the lower cover portion surrounded by the inlet.

7. The combustion device according to claim 1 or 2, characterized in that: The input port is circular, At least one of the ignition unit and the detection unit is disposed on the lower cover around the inlet.

8. The combustion device according to claim 1 or 2, characterized in that: At least one of the ignition parts is located in a region of the combustion tube where no mixed gas fuel accumulates.

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