JP7699088B2 - Shock Wave Generator - Google Patents

Description

This disclosure relates to a shock wave generating device for generating shock waves by detonation.

For example, in waste incinerators, integrated coal gasification combined cycle (IGCC) plants, and power generation boilers, dust contained in the exhaust gas adheres to the inner walls of the furnace and the outer surfaces of the heat transfer tubes. Dust that adheres to the inner walls of the furnace and the outer surfaces of the heat transfer tubes reduces the heat transfer coefficient, worsening the heat recovery efficiency, and acts as resistance to the flow of exhaust gas, reducing the performance of the furnace. For this reason, it is necessary to regularly remove dust that has adhered to the inner walls of the furnace and the outer surfaces of the heat transfer tubes using a dust removal device.

The dust removal device has a shock wave generating device. The shock wave generating device burns fuel to generate shock waves due to detonation in which the flame propagation speed exceeds the speed of sound. The dust removal device removes dust using the shock waves generated by the shock wave generating device. Examples of such conventional shock wave generating devices include those described in the following patent documents.

Patent No. 6600313

The shock wave generating device supplies a mixture of fuel and oxidizer to the combustion chamber, and ignites the mixture when a specified amount of the mixture is filled in the combustion chamber. The mixture then burns, generating a shock wave through detonation. In this case, when the mixture is supplied to the combustion chamber, the pressure of the pressure vessel upstream of the combustor is monitored to determine the total amount of the mixture supplied. However, since the pressure in the combustion chamber fluctuates while the mixture is being supplied to the combustion chamber, the instantaneous flow rate at this time cannot be determined, making it difficult to precisely control the flow rate of the mixer to the combustion chamber.

The present disclosure aims to solve the above-mentioned problems and provide a shock wave generating device that improves the accuracy of controlling the amount of flammable gas supplied to the combustion chamber.

The shock wave generating device of the present disclosure for achieving the above object includes a combustion device having a gas passage through which combustion gas flows from a base end to a tip end and an opening at the tip end, a fuel supply path for supplying fuel, an oxidizer supply path for supplying an oxidizer, a flammable gas supply path for supplying a flammable gas mixture of the fuel and the oxidizer to the combustion device, a fuel flow rate regulator for regulating the flow rate of the fuel flowing through the fuel supply path, an oxidizer flow rate regulator for regulating the flow rate of the oxidizer flowing through the oxidizer supply path, and an ignition device for igniting the flammable gas supplied to the combustion device.

The shock wave generating device disclosed herein can achieve high precision control of the amount of flammable gas supplied to the combustion device.

FIG. 1 is a schematic diagram showing a shock wave generating device according to a first embodiment. FIG. 2 is a graph showing the control of the supply amount of flammable gas in the shock wave generating device of the second embodiment. FIG. 3 is a schematic diagram showing a shock wave generating device according to the third embodiment. FIG. 4 is a schematic diagram showing a shock wave generating device according to the fourth embodiment. FIG. 5 is a schematic diagram showing a shock wave generating device according to the fifth embodiment. FIG. 6 is a front view showing the shock wave generating device from the furnace side. FIG. 7 is a flowchart showing a method for generating shock waves by the shock wave generating device. FIG. 8 is a time chart showing a method of generating shock waves by the shock wave generating device.

Below, a preferred embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the various embodiments. Furthermore, the components in the embodiments include those that a person skilled in the art would easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[First embodiment]
<Shock wave generating device>
FIG. 1 is a schematic diagram showing a shock wave generating device according to a first embodiment.

As shown in FIG. 1, the shock wave generating device 10 of the first embodiment is applied to a dust removing device that removes dust attached to the inner wall surface and the outer surface of a heat transfer tube of a furnace such as a waste incinerator, a coal gasification combined cycle power generation facility, or a power generation boiler (hereinafter referred to as a boiler). The furnace is composed of a wall portion that surrounds the combustion field of the boiler, and the dust removing device can remove dust attached to the inner wall surface of the wall portion that continues to the upper and lower parts of the furnace. The dust removing device supplies combustible gas into the furnace through a pipe that communicates with the inside of the furnace, and generates a shock wave S by detonation by igniting the combustible gas. That is, when the combustible gas burns, a detonation wave that is a combination of a flame and a shock wave propagates, and propagates as a shock wave when the combustible gas is gone. The dust removing device blows off and removes the attached dust by applying the shock wave S by detonation to the inner wall of the furnace and the outer surface of the heat transfer tube.

The shock wave generating device 10 is provided in the dust removal device, and generates a shock wave S by detonation caused by fuel combustion when the dust removal device is operating while the boiler is stopped.

The shock wave generating device 10 includes a combustion device 11, a flammable gas supply device 12, an ignition device 13, and a control device 14.

The combustion device 11 has a gas passage 21 through which combustion gas flows from the base end to the tip end. The combustion device 11 has a detonator 22 and a combustor 23. The gas passage 21 is composed of a first passage 24 provided inside the detonator 22 and a second passage 25 provided inside the combustor 23.

The detonator 22 has a cylindrical shape, the base end 22a is closed, and the tip 22b is open. The detonator 22 has a first passage 24 of a predetermined length provided therein. The detonator 22 has a flammable gas supply device 12 connected to the base end 22a. The combustor 23 has a cylindrical shape, the base end 23a is connected to the tip 22b of the detonator 22 and communicates with it, and the tip 23b is open and an opening 23c is provided. The gas passage 21 of the detonator 22 and the second passage 25 of the combustor 23 are concentric. However, the gas passage 21 of the detonator 22 and the second passage 25 of the combustor 23 do not have to be concentric and may have different shapes. The combustor 23 has a second passage 25 of a predetermined length provided therein. The second passage 25 of the combustor 23 has a larger diameter than the first passage 24 of the detonator 22. The second passage 25 of the combustor 23 has the same diameter from the base end 23a to the tip 22b, but the tip 22b may have a larger diameter than the base end 23a.

The detonator 22 is provided with a mixing promoter 26 at the base end 22a. The mixing promoter 26 promotes the mixing of the fuel F and the oxidizer A. The mixing promoter 26 is, for example, a diffuser, a vortex generator consisting of multiple protrusions, a flow straightener such as a grid, or a combination of these. The opening 23c at the tip 23b of the combustor 23 communicates with the internal space 103 defined by the furnace wall 102 of the furnace 101.

The flammable gas supplying device 12 has a fuel supplying unit 31 and an oxidizer supplying unit 41. The fuel supplying unit 31 supplies fuel F. The oxidizer supplying unit 41 supplies oxygen or air as oxidizer A. The flammable gas supplying device 12 supplies a mixture of the fuel F supplied by the fuel supplying unit 31 and the oxidizer A supplied by the oxidizer supplying unit 41 as flammable gas M from the base end of the combustion device 11 to the inside.

The fuel supply unit 31 has a fuel supply path 32, a fuel cylinder 33, a pressure reducing valve 34, a mass flow controller (fuel flow rate control device) 35, a safety device 36, a fuel supply valve 37, and a check valve 38. The fuel supply path 32 has a fuel cylinder 33 connected to the upstream end, and a pressure reducing valve 34, a mass flow controller 35, a safety device 36, a fuel supply valve 37, and a check valve 38 provided downstream. The fuel cylinder 33 stores fuel F. The pressure reducing valve 34 reduces the pressure of the fuel F in the fuel cylinder 33 and adjusts the pressure of the fuel F to be supplied. The mass flow controller 35 measures the mass flow rate of the fuel F, compares the measured mass flow rate of the fuel F with a preset set value of the fuel F, and adjusts the opening of the flow control valve so that the mass flow rate of the fuel F becomes the set value. The safety device 36 prevents flashback. The fuel supply valve 37 is an on-off valve that supplies fuel F when open and stops the supply of fuel F when closed. The check valve 38 prevents the backflow of fuel F and flammable gas M upstream.

The oxidizer supply unit 41 has an oxidizer supply path 42, an oxidizer cylinder 43, a pressure reducing valve 44, a mass flow controller (oxidizer flow rate control device) 45, a safety device 46, an oxidizer supply valve 47, and a check valve 48. The oxidizer supply path 42 has an oxidizer cylinder 43 connected to the upstream end, and a pressure reducing valve 44, a mass flow controller 45, a safety device 46, an oxidizer supply valve 47, and a check valve 48 provided toward the downstream side. The oxidizer cylinder 43 stores oxidizer A. The pressure reducing valve 44 reduces the pressure of oxidizer A in the oxidizer cylinder 43 and adjusts the pressure of the oxidizer A to be supplied. The mass flow controller 45 measures the mass flow rate of oxidizer A, compares the measured mass flow rate of oxidizer A with a preset set value of oxidizer A, and adjusts the opening of the flow control valve so that the mass flow rate of oxidizer A becomes the set value. The safety device 46 prevents backfire. The oxidizer supply valve 47 is an on-off valve that supplies oxidizer A when open and stops the supply of oxidizer A when closed. The check valve 48 prevents the backflow of oxidizer A and flammable gas M upstream.

The downstream ends of the fuel supply path 32 and the oxidizer supply path 42 are connected to the upstream end of the combustible gas supply path 52 via a cross joint 51, and the downstream end of the combustible gas supply path 52 is connected to the base end 22a of the detonator 22. The upstream end of the purge gas path 53 is connected to a blower 54, and the downstream end is connected to the cross joint 51. The purge gas path 53 is provided with a purge gas supply valve 55. The cross joint 51 connects the fuel supply path 32, the oxidizer supply path 42, the combustible gas supply path 52, and the purge gas path 53. The blower 54 supplies purge gas (e.g., air, inert gas, etc.) P to the combustible gas supply path 52. The purge gas supply valve 55 is an open/close valve that supplies purge gas P when open and stops the supply of purge gas P when closed.

The ignition device 13 ignites the combustible gas M supplied to the detonator 22 in the combustion device 11. The ignition device 13 is provided at the base end 22a of the detonator 22.

The control device 14 is connected to the ignition device 13, the mass flow controller 35, the fuel supply valve 37, the mass flow controller 45, the oxidizer supply valve 47, and the purge gas supply valve 55.

The control device 14 can control the timing of ignition of the combustible gas M by the ignition device 13. The control device 14 can adjust and control the mass flow controller 35 and the mass flow controller 45. The control device 14 can control the opening and closing of the fuel supply valve 37, the oxidizer supply valve 47, and the purge gas supply valve 55.

Here, the control device 14 is a controller, and is realized by, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) executing various programs stored in the memory unit using the RAM as a working area.

<Flow rate regulation control of flammable gas>
The mass flow controller 35 measures the mass flow rate of the fuel F flowing through the fuel supply path 32, compares the mass flow rate of the fuel F with the set value of the fuel F, and adjusts the opening of the flow control valve so that the mass flow rate of the fuel F becomes the set value. The set value of the fuel F is set according to the form of the combustion device 11, the combustion information, etc. The mass flow controller 45 measures the mass flow rate of the oxidizer A flowing through the oxidizer supply path 42, compares the mass flow rate of the oxidizer A with the set value of the oxidizer A, and adjusts the opening of the flow control valve so that the mass flow rate of the oxidizer A becomes the set value. The set value of the oxidizer A is set according to the form of the combustion device 11, the combustion information, etc. The set values of the fuel F and the oxidizer A may be set by adjusting the mass flow controllers 35 and 45 in advance, or may be set by the control device 14. The mixture ratio R of the combustible gas M is set according to the set values of the fuel F and the oxidizer A.

The amount of combustible gas M supplied by the combustible gas supply device 12 to the combustion device 11 is determined by the set values of fuel F and oxidizer A set by the mass flow controllers 35, 45 and the open times of the fuel supply valve 37 and the oxidizer supply valve 47. The control device 14 sets the set values of fuel F and oxidizer A by the mass flow controllers 35, 45 and controls the open times of the fuel supply valve 37 and the oxidizer supply valve 47. In other words, by setting the set values of fuel F and oxidizer A by the mass flow controllers 35, 45, the control device 14 can obtain the instantaneous supply amounts (mixture ratio) of fuel F and oxidizer A when the combustible gas supply device 12 is supplying combustible gas M to the combustion device 11.

By applying the mass flow controllers 35, 45, it is possible to control the instantaneous flow rate when the combustible gas supply device 12 supplies the combustible gas M to the combustion device 11. Therefore, when the combustible gas M is supplied to the combustion device 11, the mixture ratio of the fuel F and the oxidizer A can be maintained constant with high precision, and a shock wave caused by detonation can be generated with stable strength. The mixture ratio of the fuel F and the oxidizer A to be controlled varies depending on the combination of the fuel F and the oxidizer A, but is in the range of R (molar ratio) = 0.001 to 20.

In addition, by setting the respective set values of fuel F and oxidizer A by the mass flow controllers 35, 45, the control device 14 can adjust the supply amount of combustible gas M by the respective opening times of the fuel supply valve 37 and the oxidizer supply valve 47. In the shock wave generating device 10, the intensity of the shock wave caused by the detonation is basically increased by supplying a larger amount of combustible gas M (fuel F). However, for example, when the amount of dust to be removed is small, it is not necessary to increase the supply amount of combustible gas M (fuel F) to increase the intensity of the shock wave caused by the detonation. Therefore, the control device 14 adjusts the supply amount of combustible gas M by the respective opening times of the fuel supply valve 37 and the oxidizer supply valve 47, and for example, supplies an amount of combustible gas M (fuel F) according to the amount of dust to be removed. By such control, the amount of fuel F and oxidizer A used can be suppressed, and the running cost can be reduced.

[Second embodiment]
Fig. 2 is a graph showing the supply amount control of the flammable gas in the shock wave generating device of the second embodiment. The basic configuration of the second embodiment is the same as that of the first embodiment described above, and will be described using Fig. 1. The same reference numerals are used to designate members having the same functions as those of the first embodiment, and detailed description thereof will be omitted.

As shown in FIG. 1, the shock wave generating device 10 includes a combustion device 11, a combustible gas supply device 12, an ignition device 13, and a control device 14. The control device 14 can adjust the amount of combustible gas M supplied to the combustion device 11 by adjusting the opening times of the fuel supply valve 37 and the oxidizer supply valve 47. In addition, the mass flow controllers 35 and 45 set the respective set values of the supply amount of fuel F and oxidizer A per unit time. The control device 14 can adjust the mixture ratio R of fuel F and oxidizer A in the combustible gas M by changing the respective set values of fuel F and oxidizer A set by the mass flow controllers 35 and 45.

When the combustible gas supply device 12 supplies combustible gas M to the combustion device 11, the control device 14 adjusts the mixture ratio R of the combustible gas M by changing the setting values of the mass flow controllers 35, 45.

When the combustible gas supply device 12 supplies combustible gas M to the combustion device 11, the mixture ratio R of the combustible gas M may fluctuate due to external factors, even if the set values of the mass flow controllers 35, 45 are constant. For example, the inside of the combustion device 11 is filled with purge gas P until just before the shock wave generating device 10 is activated. Here, when the purge gas P is air, the inside of the combustion device 11 is filled with air, which is an oxidizer. Therefore, even if the combustible gas supply device 12 starts supplying combustible gas M at a predetermined mixture ratio R to the combustion device 11, the oxidizer (air) remaining in the combustion device 11 will mix with the combustible gas M at the beginning of the supply, and the mixture ratio will decrease.

Therefore, at the beginning of the supply of the combustible gas M to the combustion device 11 by the combustible gas supply device 12, the control device 14 changes the setting value of the mass flow controllers 35, 45 to a mixture ratio R at which the fuel F becomes excessive. Here, the beginning of the supply of the combustible gas M is a predetermined period set in advance from the time when the fuel supply valve 37 and the oxidizer supply valve 47 are opened. As shown in Figures 1 and 2, at time t0, the control device 14 operates the combustible gas supply device 12 to open the fuel supply valve 37 and the oxidizer supply valve 47, and starts the supply of the combustible gas M to the combustion device 11. At this time, the control device 14 sets the setting value of the mass flow controllers 35, 45 to a mixture ratio R at which the fuel F becomes excessive. For example, the control device 14 changes the setting value of the mass flow controllers 35, 45 so that the initial mixture ratio (fuel/oxidizer) Rg becomes a value obtained by multiplying a predetermined mixture ratio R set in advance by a coefficient a (1 < a < 10). Then, at time t1, the initial mixture ratio Rg is reached, at which fuel F is in excess.

The control device 14 maintains the initial mixture ratio Rg constant, for example, from time t1 to time t2. Then, the control device 14 reduces the mixture ratio (fuel/oxidizer) R from time t2 to time t3. For example, the control device 14 reduces the mixture ratio Rg from the initial mixture ratio Rg at which fuel F becomes excessive to a predetermined mixture ratio R from time t2 to time t3. In this case, the mixture ratio R changes continuously, but it may also change in steps. Then, at time t3, the operation of the combustible gas supply device 12 is stopped and the fuel supply valve 37 and the oxidizer supply valve 47 are closed, and the supply of the combustible gas M ends at time t4.

In the above description, the initial mixture ratio Rg is kept constant from time t1 to time t2, and the mixture ratio R is reduced from time t2 to time t3, but this is not limiting. For example, the initial mixture ratio Rg may be reduced to the mixture ratio R from time t1 to time t3, or the initial mixture ratio Rg may be reduced to the mixture ratio R from time t1 to time t2, and the mixture ratio R may be maintained constant from time t2 to time t3. The coefficient a and the degree of change for setting the initial mixture ratio Rg may be determined in advance by CFD analysis or the like and given as a sequence, or the amount of remaining air inside the combustion device 11 may be measured by a measuring device (not shown) and feedback control may be applied to the mixture ratio R.

The ignition device 13 is disposed at the base end of the combustion device 11. Therefore, the ignition device 13 ignites the combustible gas M just before the supply to the combustion device 11 is completed. At this time, the ignition device 13 wants to steadily ignite the combustible gas M inside the combustion device 11. Therefore, at the end of the supply of combustible gas M to the combustion device 11 by the combustible gas supply device 12, the control device 14 changes the setting value of the mass flow controllers 35, 45 to change the mixture ratio R to one that makes it easy for the ignition device 13 to ignite the combustible gas M. Here, the end of the supply is a predetermined period set in advance back from the stop time of the fuel supply valve 37 and the oxidizer supply valve 47 during the opening time, which is set according to the amount of combustible gas M filled in the combustion device 11. That is, the control device 14 changes the set values of the mass flow controllers 35, 45 so that the mixture ratio R approaches the stoichiometric mixture ratio Rs, which is the ratio at which the fuel F and the oxidizer A react just right at time t3, which is the end of the supply of the combustible gas M. The stoichiometric mixture ratio Rs is, for example, a value obtained by multiplying a predetermined mixture ratio R set in advance by a coefficient b (0.3<b<3).

[Third embodiment]
3 is a schematic diagram showing a shock wave generating device according to a third embodiment of the present invention. Note that the same reference numerals are used to designate members having the same functions as those in the first embodiment described above, and detailed descriptions thereof will be omitted.

The shock wave generating device 10A includes a combustion device 11, a combustible gas supply device 12A, an ignition device 13, and a control device 14. The combustion device 11, the ignition device 13, and the control device 14 are the same as those in the first embodiment.

The combustible gas supply device 12A has a fuel supply unit 31A and an oxidizer supply unit 41A. The fuel supply unit 31A has a fuel supply path 32, a fuel cylinder 33, a pressure reducing valve 34, a sonic nozzle (fuel flow rate control device) 61, a safety device 36, a fuel supply valve 37, and a check valve 38. In the second embodiment, the fuel flow rate control device is changed from the mass flow controller 35 of the first embodiment to a sonic nozzle 61. In addition, the oxidizer supply unit 41A has an oxidizer supply path 42, an oxidizer cylinder 43, a pressure reducing valve 44, a sonic nozzle (oxidizer flow rate control device) 71, a safety device 46, an oxidizer supply valve 47, and a check valve 48. In the second embodiment, the oxidizer flow rate control device is changed from the mass flow controller 45 of the first embodiment to a sonic nozzle 71.

The sonic nozzles 61, 71 are not controlled by the control device 14, and the set values of the fuel F and the oxidizer A are preset. Note that although the sonic nozzles 61, 71 are provided as the fuel flow rate control device and the oxidizer flow rate control device, orifices may also be used.

By using sonic nozzles 61, 71 and orifices as fuel flow rate control devices and oxidizer flow rate control devices, the instantaneous flow rate of the combustible gas M supplied by the combustible gas supply device 12A to the combustion device 11 can be appropriately adjusted.

[Fourth embodiment]
4 is a schematic diagram showing a shock wave generating device according to a fourth embodiment of the present invention. Note that the same reference numerals are used to designate members having the same functions as those in the first embodiment described above, and detailed descriptions thereof will be omitted.

The shock wave generating device 10B includes a combustion device 11, a combustible gas supply device 12B, an ignition device 13, and a control device 14. The combustion device 11, the ignition device 13, and the control device 14 are the same as those in the first embodiment.

The combustible gas supply device 12B has a fuel supply unit 31B and an oxidizer supply unit 41B. The fuel supply unit 31B has a fuel supply path 32, a fuel cylinder 33, a pressure reducing valve 34, a sonic nozzle device (fuel flow rate adjustment device) 61B, a safety device 36, a fuel supply valve 37, and a check valve 38. In the third embodiment, the fuel flow rate adjustment device is changed from the mass flow controller 35 of the first embodiment to the sonic nozzle device 61B. In addition, the oxidizer supply unit 41B has an oxidizer supply path 42, an oxidizer cylinder 43, a pressure reducing valve 44, a sonic nozzle device (oxidizer flow rate adjustment device) 71B, a safety device 46, an oxidizer supply valve 47, and a check valve 48. In the third embodiment, the oxidizer flow rate adjustment device is changed from the mass flow controller 45 of the first embodiment to the sonic nozzle device 71B.

In the sonic nozzle device 61B, the fuel supply path 32 is provided with a first fuel branch path 62 and a second fuel branch path 63 in parallel between the pressure reducing valve 34 and the safety device 36. The first fuel branch path 62 and the second fuel branch path 63 are provided with a first sonic nozzle 64 and a second sonic nozzle 65, a first on-off valve 66 and a second on-off valve 67, respectively. The control device 14 can control the opening and closing of the first on-off valve 66 and the second on-off valve 67. In the sonic nozzle device 71B, the oxidizer supply path 42 is provided with a first oxidizer branch path 72 and a second fuel branch path 73 in parallel between the pressure reducing valve 44 and the safety device 46. The first oxidizer branch path 72 and the second fuel branch path 73 are provided with a first sonic nozzle 74 and a second sonic nozzle 75, a first on-off valve 76 and a second on-off valve 77, respectively. The control device 14 can control the opening and closing of the first opening and closing valve 76 and the second opening and closing valve 77. Note that the sonic nozzles 64, 65, 74, and 75 may be orifices.

The control device 14 can adjust the mixture ratio R of the fuel F and the oxidizer A in the combustible gas M supplied to the combustion device 11 by controlling the opening and closing of the first and second opening and closing valves 66 and 67, and controlling the opening and closing of the first and second opening and closing valves 76 and 77. For example, when the first and second opening and closing valves 66 and 67 and the first and second opening and closing valves 76 and 77 are opened, the mixture ratio of the fuel F and the oxidizer A in the combustible gas M becomes a predetermined mixture ratio R that has been set in advance. Also, when the first and second opening and closing valves 66 and 76 and 77 are opened and the second opening and closing valve 67 is closed, the mixture ratio of the fuel F and the oxidizer A in the combustible gas M becomes an excess of oxidizer A with respect to the predetermined mixture ratio R. On the other hand, when the first on-off valve 66, the second on-off valve 67, and the first on-off valve 76 are opened and the second on-off valve 77 is closed, the mixture ratio of fuel F and oxidizer A in the flammable gas M becomes an excess of fuel F with respect to the predetermined mixture ratio R.

The maximum valve opening degree of the first on-off valve 66 and the second on-off valve 67 may be set to different values, or the maximum valve opening degree of the first on-off valve 76 and the second on-off valve 77 may be set to different values. In addition, the fuel supply path 32 and the oxidizer supply path 42 are not limited to being two-branched, and may be three or more-branched.

By using the sonic nozzle devices 61B and 71B as the fuel flow rate control device and the oxidizer flow rate control device, the instantaneous flow rate of the combustible gas M supplied to the combustion device 11 by the combustible gas supply device 12B can be appropriately adjusted.

[Fifth embodiment]
<Shock wave generating device>
Fig. 5 is a schematic diagram showing the shock wave generating device of the fifth embodiment, and Fig. 6 is a front view of the shock wave generating device from the furnace side. Note that the same reference numerals are used to designate members having the same functions as those in the first embodiment, and detailed descriptions thereof will be omitted.

As shown in Figures 5 and 6, the shock wave generating device 10C includes a combustion device 11, a combustible gas supply device 12, an ignition device 13, a control device 14, and an ejection section 15.

The furnace 101 has a furnace wall 102. The furnace 101 has an internal space 103 defined by the inner wall surface 102a of the furnace wall 102. In the internal space 103 of the furnace 101, a heat transfer tube constituting a heat exchanger (not shown) is arranged. In the internal space 103 of the furnace 101, high-temperature exhaust gas G1 flows in a predetermined direction. The flow direction of the high-temperature exhaust gas G1 varies depending on the position of the internal space 103 and the surrounding shape, but the following describes the case where the high-temperature exhaust gas G1 rises in the internal space 103.

The combustion device 11 has a detonator 22 and a combustor 23A. The detonator 22 is capable of supplying flammable gas M to the internal space 103, which is the target area. The detonator 22 is, for example, cylindrical in shape and has the same inner diameter in the longitudinal direction. However, the detonator 22 is not limited to a cylindrical shape and may be a polygonal tube shape. The detonator 22 has one axial end connected to the flammable gas supply device 12 and the other end connected to the combustor 23A.

The combustor 23A has a pipe 23Aa and an expansion tube 23Ab, and is provided between the initiation tube 22 and the furnace wall 102 (internal space 103) of the furnace 101. The inner diameter of the pipe 23Aa on the furnace wall 102 side is larger than the inner diameter of the initiation tube 22. The expansion tube 23Ab expands continuously and uniformly from the pipe 23Aa side toward the furnace wall 102 (internal space 103) side. That is, one end of the expansion tube 23Ab in the axial direction has the same diameter as the pipe 23Aa, and the base end of the pipe 23Aa is connected to the other end of the initiation tube 22. The diameter of the expansion tube 23Ab gradually expands from one end to the other end in the axial direction and is connected to the furnace wall 102. In addition, since the combustor 23A is subjected to a recoil caused by a shock wave generated by the detonation of the flammable gas M inside, the connection part of the combustor 23A to the furnace wall 102 may be made movable.

The ejection section 15 ejects non-combustible gas N from the outer periphery of the expansion tube 23Ab in the combustor 23A toward the center. The ejection section 15 is provided on the other end side of the expansion tube 23Ab, that is, on the furnace 101 (internal space 103) side.

The outer cylinder pipe 81 is disposed on the outside of the other end of the diverter pipe 23Ab. The outer cylinder pipe 81 has a cylindrical shape with a larger diameter than the diverter pipe 23Ab, and like the diverter pipe 23Ab, the diameter of the outer cylinder pipe 81 is continuously and uniformly expanded from one end to the other end in the axial direction. The inner peripheral surface of the outer cylinder pipe 81 is disposed with a gap from the outer peripheral surface of the diverter pipe 23Ab, and the outer peripheral surface is fitted and fixed in the through hole 102b of the furnace wall 102. Therefore, the other end side of the diverter pipe 23Ab is disposed inside the furnace wall 102, and the entire outer cylinder pipe 81 is disposed inside the furnace wall 102. The outer cylinder pipe 81 may also be connected to the furnace wall 102 so as to be freely movable, like the diverter pipe 23Ab.

The outer tube 81 has an outer tube portion 81a and a flange portion 81b. The outer tube portion 81a is disposed with a gap from the outer peripheral surface of the expanding tube 23Ab. The flange portion 81b is disposed on the other axial end side of the outer tube 81, with its outer peripheral portion connected to the other end of the outer tube portion 81a and its inner peripheral portion connected to the other end of the expanding tube 23Ab. Therefore, a cylindrical gas flow portion 82 is formed between the expanding tube 23Ab and the outer tube 81.

The outer cylinder pipe 81 has a header 83 arranged on one end side in the axial direction. The header 83 is ring-shaped and has an L-shaped cross section. One end of the header 83 in the width direction is fixed to the outer wall surface 102c of the furnace wall 102, and the other end is fixed to the outer peripheral surface of the diffuser 23Ab. Therefore, the header 83 defines a ring-shaped gas space portion 84 between the furnace wall 102 and the diffuser 23Ab. The gas space portion 84 is connected to one end side of the gas flow portion 82. The header 83 may also be connected to the furnace wall 102 in a movable manner, like the diffuser 23Ab and the outer cylinder pipe 81. The header 83 may also be fixed to the outer cylinder pipe 81 to define the gas space portion 84.

The ejection section 15 has multiple (eight in this embodiment) ejection holes 15a that eject the non-combustible gas N. The multiple ejection holes 15a are formed on the other axial end side of the combustor 23A, that is, on the side of the internal space 103 of the furnace 101. The multiple ejection holes 15a are slit-shaped openings that run along the circumferential direction of the expansion tube 23Ab. However, the number of ejection holes 15a is not limited. In addition, the ejection holes 15a are not limited to slit shapes, and may be circular holes.

The multiple ejection holes 15a constituting the ejection section 15 eject non-combustible gas N in an inclined direction inclined toward the internal space 103 of the furnace 101 with respect to the radial direction of the expanding tube 23Ab. That is, one end of the expanding tube 23Ab expands in diameter toward the other end. The multiple ejection holes 15a are holes that penetrate in a direction perpendicular to the other end of the expanding expanding tube 23Ab. Therefore, the multiple ejection holes 15a eject non-combustible gas N from the outer periphery of the combustor 23A toward the internal space 103.

Incidentally, the expanding tube 23Ab is set to a predetermined expansion ratio. For example, when the inside diameter of the expanding tube 23Ab is R1 at one end and R2 at the other end, it is preferable to set the area ratio of (R2/2) ² π/(R1/2) ² π = 1.4 to 4.0. It is also preferable to set the angle α of the inner surface of the expanding tube 23Ab with respect to the center line = 10 degrees to 50 degrees. It is also preferable to set the ejection angle β of the non-flammable gas N of the ejection hole 15a with respect to the radial direction of the expanding tube 23Ab = 0 degrees to 45 degrees.

One end of a gas supply line 86 is connected to the header 83 via a port 85. A gas supply source 87 is connected to the other end of the gas supply line 86, and an on-off valve 88 is provided in the middle. Here, the gas supply source 87 is, for example, a blower or a compressor, and supplies air or compressed air as the non-flammable gas N. However, the gas supply source 87 is not limited to this configuration. For example, the non-flammable gas N may be a gas with a lower oxygen fraction than air or an inert gas (such as nitrogen or argon) instead of air, and the gas supply source 87 may be a tank for storing these gases.

Therefore, when the control device 14 opens the on-off valve 88, non-combustible gas N is supplied from the gas supply source 87 to the gas supply line 86 and then supplied to the gas space portion 84 via the port 85. The non-combustible gas N supplied to the gas space portion 84 flows through the gas flow portion 82 toward the other end side of the combustor 23A and is ejected from the multiple ejection holes 15a toward the center side of the combustor 23A.

<Action of the shock wave generating device>
When dust adheres to the inner wall surface 102a of the furnace wall 102 or the heat transfer tube (not shown) of the heat exchanger due to long-term use in the furnace 101, the dust removal device is operated. That is, the supply device supplies and fills the combustible gas M into the detonator 22, and the combustible gas M is ignited. The combustible gas M then burns inside the detonator 22, generating a flame C, which generates a shock wave S due to detonation. The generated shock wave S is transmitted to the internal space 103 through the detonator 22 and the combustor 23A, and acts on the inner wall surface 102a of the furnace wall 102 and the outer surface of the heat transfer tube, blowing off and removing the attached dust. At this time, the shock wave S caused by the detonation generated in the detonator 22 is transmitted to the internal space 103 of the furnace 101 through the expanding expansion tube 23Ab, so that the supersonic flow ejected together with the blast can be expanded at an appropriate area ratio to efficiently introduce the blast and jet into the internal space 103. When the dust removal device removes the dust adhering to the inner wall surface 102a of the furnace wall 102 and the outer surface of the heat transfer tube, the operation of the dust removal device is stopped.

When the dust removal device described above removes dust, the combustible gas M filled inside the detonator 22 and the combustor 23A may spontaneously ignite. Therefore, when the dust removal device is in operation, the ejection section 15 is operated. That is, the on-off valve 88 is opened, and non-combustible gas N is supplied from the gas supply source 87 through the gas supply line 86 to the gas space section 84. Then, the non-combustible gas N filled in the gas space section 84 flows through the gas flow section 82 to the other end side of the combustor 23A, and is ejected from the multiple ejection holes 15a toward the center side of the expansion tube 23Ab.

At this time, the ejection section 15 ejects non-combustible gas N from multiple ejection holes 15a toward the center of the combustor 23A, forming an air curtain between the inside of the expander 23Ab and the internal space 103 of the furnace 101. The air curtain of non-combustible gas N separates the inside of the expander 23Ab from the internal space 103, so that, for example, rising exhaust gas E is prevented from penetrating the internal space 103 into the inside of the combustor 23A through the expander 23Ab. Therefore, spontaneous ignition of the combustible gas M filled in the detonator 22 due to contact with the high-temperature exhaust gas E is prevented.

However, due to the flow velocity or drift of the exhaust gas E rising in the internal space 103, some of the exhaust gas E may slip through the air curtain of the non-flammable gas N and enter the diffuser 23Ab. At this time, since the inner diameter (area) of the diffuser 23Ab on the furnace wall 102 side is larger than that on the detonator 22 side, the exhaust gas E that has entered the diffuser 23Ab from the internal space 103 becomes a secondary flow N1 that swirls counterclockwise in FIG. 5 inside the diffuser 23Ab. Therefore, the exhaust gas E that has entered the diffuser 23Ab becomes the secondary flow N1, swirls and stagnates inside the diffuser 23Ab, and is less likely to flow toward the detonator 22 side, suppressing spontaneous ignition of the combustible gas M filled in the detonator 22.

In addition, even if a portion of the exhaust gas E that has entered the expansion tube 23Ab comes into contact with the combustible gas M filled in the detonator 22, the temperature of the exhaust gas E drops as it flows through the expansion tube 23Ab. That is, the combustible gas M in the detonator 22 is mixed with the exhaust gas E whose temperature has been reduced, and is diluted, so that the concentration of the combustible gas M in the detonator 22 decreases without spontaneous ignition. Therefore, even if the mixed gas of the combustible gas M and the exhaust gas E returns to the internal space 103 through the combustor 23A, spontaneous ignition of the combustible gas M is suppressed.

<Control of shock wave generating device>
FIG. 7 is a flowchart showing a method for generating shock waves by the shock wave generating device.

As shown in FIG. 5 and FIG. 6, in step S10, the control device 14 opens the purge gas supply valve 55 and supplies purge gas P to the combustion device 11. At this time, water may be sprayed to lower the internal temperature of the combustion device 11. Then, when generating a shock wave, in step S11, the control device 14 closes the purge gas supply valve 55 and stops the supply of purge gas P to the combustion device 11. In step S12, the control device 14 opens the fuel supply valve 37 to start the supply of fuel F. In step S13, the control device 14 opens the oxidizer supply valve 47 to start the supply of oxidizer A. Then, the flammable gas M, which is a mixture of fuel F and oxidizer A, is supplied to the detonator 22 of the combustion device 11.

In step S14, the control device 14 opens the on-off valve 88 to start the supply of non-combustible gas N. The non-combustible gas N is then ejected from the multiple ejection holes 15a toward the center of the combustor 23A, forming an air curtain between the inside of the combustor 23A and the internal space 103 of the furnace 101. The air curtain of non-combustible gas N separates the inside of the combustor 23A from the internal space 103, and prevents the exhaust gas E from penetrating into the inside of the combustor 23A.

In step S15, the control device 14 determines whether a predetermined filling time Ta has elapsed since the start of the supply of fuel F and oxidizer A, i.e., the supply of combustible gas M to the combustion device 11. The filling time Ta is set according to the amount of combustible gas M filled into the combustion device 11. Here, if the control device 14 determines that the filling time Ta has not elapsed (No), it waits in this state. On the other hand, if the control device 14 determines that the filling time Ta has elapsed (Yes), in step S16, the control device 14 closes the fuel supply valve 37 to stop the supply of fuel F. Then, in step S17, the control device 14 closes the oxidizer supply valve 47 to stop the supply of oxidizer A.

In step S18, the control device 14 determines whether a predetermined ignition waiting time Tb has elapsed since the supply of fuel F and oxidizer A was stopped, that is, the supply of combustible gas M to the combustion device 11 was stopped. The ignition waiting time Tb is set, for example, taking into consideration the operation time until the fuel supply valve 37 and the oxidizer supply valve 47 are completely closed. Here, if the control device 14 determines that the ignition waiting time Tb has not elapsed (No), it waits as it is. On the other hand, if the control device 14 determines that the ignition waiting time Tb has elapsed (Yes), in step S19, the control device 14 operates the ignition device 13 to ignite the combustible gas M filled in the detonator 22. Then, in step 20, the combustible gas M remaining in the first passage 24 of the detonator 22 is ignited, and the flame C burns so as to spread from the base end 22a to the tip 22b. When the flame C of the detonator 22 reaches the combustor 23A, the flame C spreads from the base end 23a through the second passage 25 to the tip 23b, generating a shock wave S due to detonation.

When the shock wave S is generated, the flame C is extinguished, so in step S21, the control device 14 closes the on-off valve 88 to stop the supply of non-flammable gas N and releases the air curtain of non-flammable gas N. Then, in step S22, the control device 14 opens the purge gas supply valve 55 and supplies purge gas P to the combustion device 11.

<Operation of shock wave generating device>
FIG. 8 is a time chart showing a method of generating shock waves by the shock wave generating device.

At time t11, the supply of purge gas P to the combustion device 11 is stopped, and the supply of fuel F to the combustion device 11 is started, and the supply of oxidizer A to the combustion device 11 is also started. Then, flammable gas M, which is a mixture of fuel F and oxidizer A, is supplied to the detonator 22 of the combustion device 11. In addition, the supply of non-flammable gas N is started, and an air curtain is formed between the inside of the combustor 23A and the internal space 103 of the furnace 101. In this state, a predetermined amount of flammable gas M is filled inside the combustion device 11.

At time t12, when a predetermined filling time Ta has elapsed since the start of the supply of combustible gas M, the supply of fuel F to the combustion device 11 is stopped, and the supply of oxidizer A to the combustion device 11 is stopped. Then, at time t13, when a predetermined ignition waiting time Tb has elapsed, the ignition device 13 ignites the combustible gas M filled in the detonator 22. The combustible gas M is then ignited, the flame C spreads, and a shock wave S is generated by detonation. When the shock wave S is generated, at time t14, the air curtain of non-combustible gas N is released, and purge gas P is supplied to the combustion device 11.

[Effects of this embodiment]
The shock wave generating device of the first aspect includes a combustion device 11 having a gas passage 21 through which combustion gas flows from a base end to a tip end and an opening at the tip end, a fuel supply path 32 for supplying fuel, an oxidizer supply path 42 for supplying an oxidizer, a flammable gas supply path 52 for supplying flammable gas M mixed with fuel and oxidizer to the combustion device 11, a fuel flow rate control device for adjusting the flow rate of fuel flowing through the fuel supply path 32, an oxidizer flow rate control device for adjusting the flow rate of oxidizer flowing through the oxidizer supply path 42, an ignition device 13 for igniting the flammable gas M supplied to the combustion device 11, and a control device 14 for controlling the fuel flow rate control device and the oxidizer flow rate control device according to the supply state of the flammable gas M supplied to the combustion device 11.

According to the shock wave generating device of the first aspect, the fuel flow rate adjusting device and the oxidizer flow rate adjusting device can adjust the instantaneous flow rate when the flammable gas supply device 12 supplies the flammable gas M to the combustion device 11, and when the flammable gas M is supplied to the combustion device 11, the mixture ratio of the fuel F and the oxidizer A can be maintained constant with high precision, and a shock wave by detonation can be generated with stable strength. In addition, by adjusting the instantaneous flow rate of the flammable gas M with the fuel flow rate adjusting device and the oxidizer flow rate adjusting device, the amount of flammable gas M according to the application of the shock wave can be supplied, the amount of fuel F and the oxidizer A used can be suppressed, and the running cost can be reduced. As a result, the supply amount of the flammable gas M supplied to the combustion device 11 can be controlled with high precision.

The shock wave generating device according to the second aspect is the shock wave generating device according to the first aspect, and furthermore, the fuel flow rate adjusting device and the oxidizer flow rate adjusting device have mass flow controllers 35, 45. This allows the mixture ratio of fuel F and oxidizer A to be adjusted even while combustible gas M is being supplied to the combustion device 11, and allows the mixture ratio to be appropriately adjusted according to the filling state of combustible gas M in the combustion device 11.

The shock wave generating device according to the third aspect is the shock wave generating device according to the first aspect, and further, the fuel flow rate adjusting device and the oxidizer flow rate adjusting device have sonic nozzles 61, 71 or orifices. This allows the instantaneous flow rate to be robustly controlled to a constant value without relying on electronic control.

The shock wave generating device according to the fourth aspect is a shock wave generating device according to any one of the first to third aspects, and further includes a fuel flow rate adjusting device and an oxidizer flow rate adjusting device, each of which has a plurality of fuel branch paths 62, 63 and a plurality of oxidizer branch paths 72, 73 arranged in parallel in the fuel supply path 32 and the oxidizer supply path 42, respectively, sonic nozzles 64, 65, 74, 75 arranged in the plurality of fuel branch paths 62, 63 and the plurality of oxidizer branch paths 72, 73, respectively, and opening/closing valves 66, 67, 77, 78 arranged in the plurality of fuel branch paths 62, 63 and the plurality of oxidizer branch paths 72, 73, respectively. This allows for easy adjustment of the mixture ratio of fuel F and oxidizer A with a simple configuration, even while combustible gas M is being supplied to the combustion device 11.

The shock wave generating device according to the fifth aspect is the shock wave generating device according to any one of the first to fourth aspects, and further, the control device 14 controls the fuel flow rate adjustment device and the oxidizer flow rate adjustment device so that the mixture ratio of the combustible gas approaches the stoichiometric mixture ratio at least at the end of the time of filling the combustion device 11 with the combustible gas M. As a result, the ignition device 13 can ignite the combustible gas M filled in the combustion device 11, properly ignite and burn it, and generate a flame C.

The shock wave generating device according to the sixth aspect is the shock wave generating device according to the fourth or fifth aspect, and further, the control device 14 controls the fuel flow rate adjustment device and the oxidizer flow rate adjustment device so that the mixture ratio of the combustible gas M becomes fuel-excessive at the beginning of the time of filling the combustion device 11 with the combustible gas M. As a result, even if air remains inside the combustion device 11, the mixture ratio of the combustible gas M becomes fuel-excessive at the beginning of the supply, and finally, the mixture ratio of the combustible gas M inside the combustion device 11 can be adjusted to an appropriate value.

The shock wave generating device according to the seventh aspect is a shock wave generating device according to any one of the first to sixth aspects, and further has an ejection part 15 that ejects non-combustible gas N from the outer periphery of the combustion device 11 toward the center. As a result, the inside of the combustion device 11 and the internal space 103 are separated by an air curtain of non-combustible gas N, so that the infiltration of exhaust gas E into the inside of the combustion device 11 can be suppressed, and the spontaneous ignition of the combustible gas M filled in the combustion device 11 by the exhaust gas E can be suppressed. As a result, large valves and the like are not required, and the increase in parts costs and maintenance costs can be suppressed. In addition, the air curtain of non-combustible gas N that separates the combustion device 11 and the internal space 103 can be appropriately suppressed by simply providing the ejection part 15 on the combustion device 11, and there is no risk of malfunction even when placed in a high-temperature environment, and spontaneous ignition of the combustible gas M can be appropriately suppressed.

The shock wave generating device according to the eighth aspect is the shock wave generating device according to the seventh aspect, and further, the ejection unit 15 ejects non-flammable gas N at the same time as supplying flammable gas M to the combustion device 11, and stops ejecting the non-flammable gas N after igniting the flammable gas M supplied to the combustion device 11. This allows an air curtain of non-flammable gas N to be formed at an appropriate time.

In the above-mentioned embodiment, the shock wave generating device is applied to a dust removing device that removes dust adhering to the inner wall surface and the outer surface of heat transfer tubes of furnaces such as waste incinerators, integrated coal gasification combined cycle power generation facilities, and power boilers, but the application is not limited to these. The shock wave generating device can be applied to, for example, a propulsion engine that radiates a shock wave from an opening of a combustion device and receives the reaction force to generate thrust, a power engine that rotates a turbine, a device that radiates a shock wave from an opening of a combustor and uses the high pressure of the shock wave to exert a physical effect on an object placed near the opening (destruction of a structure, separation of materials, etc.), and a device that uses the high pressure of the shock wave to exert a physical effect on an object placed inside the combustion device (destruction of a structure, separation of materials, etc.).

REFERENCE SIGNS LIST 10, 10A, 10B, 10C Shock wave generating device 11 Combustion device 12, 12A, 12B Flammable gas supply device 13 Ignition device 14 Control device 15 Jet portion 15a Jet hole 21 Gas passage 22 Detonator 23, 23A Combustor 24 First passage 25 Second passage 26 Mixing promoter 31, 31A, 31B Fuel supply portion 32 Fuel supply path 33 Fuel cylinder 34 Pressure reducing valve 35 Mass flow controller (fuel flow rate adjustment device)
36 Safety device 37 Fuel supply valve 38 Check valve 41, 41A, 41B Oxidizer supply section 42 Oxidizer supply path 43 Oxidizer cylinder 44 Pressure reducing valve 45 Mass flow controller (Oxidizer flow rate adjustment device)
46 Safety device 47 Oxidizer supply valve 48 Check valve 51 Cross joint 52 Combustible gas supply path 53 Purge gas path 54 Blower 55 Purge gas supply valve 61 Sonic nozzle (fuel flow rate adjustment device)
61B Sonic nozzle device (fuel flow control device)
62 First fuel branch path 63 Second fuel branch path 64 First sonic nozzle 65 Second sonic nozzle 66 First on-off valve 67 Second on-off valve 71 Sonic nozzle (oxidizer flow rate control device)
71B Sonic nozzle device (oxidizer flow rate control device)
72 First oxidizer branch path 73 Second oxidizer branch path 74 First sonic nozzle 75 Second sonic nozzle 76 First on-off valve 77 Second on-off valve 81 External cylinder 82 Gas flow section 83 Header 84 Gas space section 85 Port 86 Gas supply line 87 Gas supply source 88 On-off valve 101 Furnace 102 Furnace wall 103 Internal space (target area)
F Fuel A Oxidizer M Combustible gas P Purge gas C Flame S Shock wave N Non-combustible gas E Exhaust gas N1 Secondary flow

Claims (6)

a combustion device provided with a gas passage through which a combustion gas flows from a base end to a tip end and with an opening provided at the tip end;
A fuel supply path for supplying fuel;
an oxidant supply path for supplying an oxidant;
a combustible gas supply path that supplies a combustible gas in which the fuel and the oxidizer are mixed to the combustion device;
a fuel flow rate adjusting device that adjusts a flow rate of the fuel flowing through the fuel supply path;
an oxidant flow rate control device that controls a flow rate of the oxidant flowing through the oxidant supply path;
an ignition device that ignites the flammable gas supplied to the combustion device;
a control device that controls the fuel flow rate control device and the oxidizer flow rate control device in accordance with a supply state of the flammable gas supplied to the combustion device;
Equipped with
the fuel flow rate control device and the oxidizer flow rate control device each have a mass flow controller,
the mass flow controller controls an opening degree of a flow control valve so that the mass flow rate becomes the set value by comparing the measured mass flow rate of the fuel or the oxidizer with a set value that is set according to the configuration of the combustion device, combustion information, and the like;
the control device controls the fuel flow rate control device and the oxidizer flow rate control device so that a mixture ratio of the combustible gas before being supplied to the combustion device becomes fuel-excessive at an early stage of a filling time of the combustible gas into the combustion device while the inside of the combustion device is filled with purge gas.
Shock wave generator. The fuel flow rate control device and the oxidizer flow rate control device each have an orifice or a sonic nozzle.
The shock wave generating device according to claim 1 . the fuel flow rate control device and the oxidizer flow rate control device each include a plurality of fuel branch paths and a plurality of oxidizer branch paths that are provided in parallel in the fuel supply path and the oxidizer supply path, respectively, the orifices or the sonic nozzles that are provided in the plurality of fuel branch paths and the plurality of oxidizer branch paths, respectively, and on-off valves that are provided in the plurality of fuel branch paths and the plurality of oxidizer branch paths,
The shock wave generating device according to claim 2 . the control device controls the fuel flow rate control device and the oxidizer flow rate control device so that a mixture ratio of the combustible gas approaches a stoichiometric mixture ratio at least at the end of a time period during which the combustible gas is filled into the combustion device.
The shock wave generating device according to any one of claims 1 to 3. The combustion device has an ejection portion that ejects a non-combustible gas from the outer periphery toward the center.
The shock wave generating device according to claim 1 . The ejection unit ejects the non-combustible gas at the same time as supplying the flammable gas to the combustion device, and stops ejecting the non-combustible gas after igniting the flammable gas supplied to the combustion device.
The shock wave generating device according to claim 5 .

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