Deposits removal system

Abstract

To provide a deposits removal system that uses a pressure wave by combustion of an inflammable gas and that reduces procurement costs for the inflammable gas.SOLUTION: There is provided a deposits removal system 15A that removes deposits on a heat exchange part exchanging heat with an exhaust gas from a combustion furnace 2, the deposits removal system comprising: electric power generation facilities 21 which use the heat obtained at the heat exchange part to generate electric power; a water electrolytic device 22 which electrolyzes water with the generated electric power to produce a hydrogen gas and an oxygen gas; a fermentation device 25 which ferments biomass to produce a biogas; and a pressure wave generation device 30 which emits the pressure wave, generated by mixing and burning the biogas and oxygen gas, toward the heat exchange part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a deposit removal system for removing deposits adhering to a heat exchange section that exchanges heat with exhaust gas from a combustion furnace.

Background Art

[0002] In recent years, in combustion facilities that burn waste and the like, power generation has been carried out by utilizing the heat of exhaust gas discharged from a combustion furnace (see, for example, Patent Document 1). Further, in combustion facilities, deposits such as dust adhering to the heat exchange section of a boiler are removed (see, for example, Patent Document 2).

[0003] Patent Document 1 discloses a combustion facility provided with a power generation facility that generates power by the cooperation of a boiler, a steam turbine, and a generator. In this combustion facility, the boiler has a heat exchange section that exchanges heat with exhaust gas from the combustion furnace, and recovers heat from the exhaust gas to generate superheated steam. The boiler and the steam turbine are connected so that superheated steam can flow through them. Further, the steam turbine and the generator are connected so that rotational power can be transmitted. In this way, the steam turbine can be rotated by the superheated steam from the boiler and power can be generated by the generator.

[0004] Patent Document 2 discloses a deposit removal device that includes a container having an opening and a sealing body that closes the opening, and generates a pressure wave by rapidly increasing the pressure inside the container by burning a mixed gas of a combustible gas and an oxidant gas supplied inside the container to break the sealing body, and discharges the generated pressure wave toward the heat exchange section of the boiler, thereby removing deposits (dust) adhering to the heat exchange section.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the combustion facility disclosed in Patent Document 1, the superheated steam for rotating the steam turbine is generated by using the heat recovered from the exhaust gas in the heat exchange section of the boiler. As the operation progresses, dust adheres and accumulates on the heat exchange section of the boiler, resulting in a decrease in heat recovery performance and a reduction in the power generation amount. If the dust adhering and accumulating on the heat exchange section of the boiler is removed using the deposit removing device disclosed in Patent Document 2, it is considered possible to prevent the reduction in the power generation amount caused by the decrease in heat recovery performance. However, when using the deposit removing device, the combustible gas supplied into the container must be procured separately, increasing the procurement cost.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a deposit removing system with reduced procurement cost of combustible gas in a deposit removing system using a pressure wave generated by combustion of combustible gas.

Means for Solving the Problems

[0008] The characteristic configuration of the deposit removing system according to the present invention for solving the above problems is a deposit removing system for removing deposits adhering to a heat exchange section that exchanges heat with exhaust gas from a combustion furnace, a power generation facility that generates power using the heat obtained in the heat exchange section, a water electrolysis device that electrolyzes water with the generated power to generate hydrogen gas and oxygen gas, a fermentation device that ferments biomass to generate biogas, a pressure wave generator that mixes and burns the biogas and the oxygen gas and emits the generated pressure wave toward the heat exchange section, and is provided with

[0009] According to the deposit removal system of this configuration, the pressure wave generator emits a pressure wave generated by mixing and burning biogas produced by fermenting biomass in a fermentation device and oxygen gas produced by a water electrolysis device toward the heat exchange unit. Therefore, the procurement cost of combustible gas can be reduced.

[0010] Next, the characteristic configuration of the deposit removal system according to the present invention for solving the above problems is A deposit removal system for removing deposits adhering to a heat exchange unit that exchanges heat with exhaust gas from a combustion furnace, Power generation equipment that generates electricity using the heat obtained in the heat exchange unit, A water electrolysis device that electrolyzes water with the generated electricity to produce hydrogen gas and oxygen gas, A fermentation device that ferments biomass to produce biogas, A reduction device that introduces the biogas and the hydrogen gas and reduces carbon dioxide contained in the biogas to methane with the hydrogen gas, A pressure wave generator that emits a pressure wave generated by mixing and burning the gas containing methane from the reduction device and the oxygen gas or air toward the heat exchange unit, It is provided with.

[0011] According to the deposit removal system of this configuration, the reduction device reduces carbon dioxide contained in biogas produced by fermenting biomass in a fermentation device to methane with hydrogen gas produced by a water electrolysis device. And the pressure wave generator emits a pressure wave generated by mixing and burning the gas containing methane from the reduction device and oxygen gas or air produced by the water electrolysis device toward the heat exchange unit. Therefore, the procurement cost of combustible gas can be reduced.

[0012] Next, the characteristic configuration of the deposit removal system according to the present invention for solving the above problems is A deposit removal system for removing deposits adhering to a heat exchange unit that exchanges heat with exhaust gas from a combustion furnace, Power generation equipment that generates electricity using the heat obtained in the heat exchange unit, A water electrolysis device that electrolyzes water using the generated electric power to produce hydrogen gas and oxygen gas, A fermentation tank that stores a fermentation broth obtained by fermenting biomass, and a fermentation device that has gas supply means for supplying the hydrogen gas to the fermentation tank and generates biogas in the fermentation tank, A pressure wave generator that emits a pressure wave generated by mixing and burning the biogas and the oxygen gas or air toward the heat exchange unit, is provided.

[0013] According to the deposit removal system of this configuration, the fermentation device has a fermentation tank that stores a fermentation broth obtained by fermenting biomass, and gas supply means for supplying the hydrogen gas generated by the water electrolysis device to the fermentation tank. In the fermentation device having such a configuration, since hydrogen gas is supplied to the fermentation broth in the fermentation tank by the gas supply means, the hydrogen gas supplied by the gas supply means is contained in the fermentation broth separately from the hydrogen generated by the decomposition of low molecular weight organic substances by acid-producing bacteria. Then, using hydrogen derived from the hydrogen gas supplied by the gas supply means and carbon dioxide inevitably generated by the decomposition of low molecular weight organic substances by acid-producing bacteria as substrates, methane gas is generated by the CO2-reducing methane production reaction of hydrogen-utilizing methanogens. In this way, carbon dioxide can be reduced with hydrogen, and the methane concentration in the biogas can be increased. And the pressure wave generator emits a pressure wave generated by mixing and burning the biogas with an increased methane concentration and the oxygen gas or air generated by the water electrolysis device toward the heat exchange unit. Therefore, in the deposit removal system using the pressure wave generated by the combustion of the combustible gas, the procurement cost of the combustible gas can be reduced. In particular, since the methane concentration in the biogas used as the combustible gas is increased, the combustibility can be improved, and a high-output pressure wave can be stably generated.

[0014] In the deposit removal system according to the present invention, the fermentation tank has an acid fermentation zone and a methane fermentation zone, it is preferable that the gas supply means supplies the hydrogen gas to the methane fermentation zone.

[0015] According to the deposit removal system of this configuration, the fermentation tank has an acid fermentation zone and a methane fermentation zone. In the acid fermentation zone, an acid production reaction is carried out in which organic substances are decomposed by acid-producing bacteria into lower organic acids such as butyric acid, propionic acid, and acetic acid. On the other hand, in the methane fermentation zone, a methane production reaction is carried out in which methane is produced from acetic acid, as well as hydrogen and carbon dioxide components, by methane-producing bacteria. By the way, when hydrogen gas from the gas supply means is supplied to the acid fermentation zone in the fermentation tank, in addition to the hydrogen by-produced in the acid production reaction carried out in the acid fermentation zone, hydrogen derived from the hydrogen gas supplied by the gas supply means accumulates and the hydrogen partial pressure rises. As a result, the production reaction of acetic acid does not proceed due to product inhibition, and consequently, the methane production rate may decrease. Therefore, according to the biomass treatment apparatus of this configuration, the hydrogen gas from the gas supply means is supplied to the methane fermentation zone in the fermentation tank. Thereby, product inhibition in the acid fermentation zone can be avoided. As a result, in the methane fermentation zone, methane is produced by the acetic acid decomposition methane production reaction using acetic acid as a substrate, and methane is also produced by the CO2 reduction methane production reaction using hydrogen and carbon dioxide as substrates, and the production efficiency of methane can be improved.

[0016] In the deposit removal system according to the present invention, It is preferable to further include a hydrogen storage and supply device that stores the hydrogen and supplies the stored hydrogen to a hydrogen demand destination.

[0017] According to the deposit removal system of this configuration, the hydrogen generated by the water electrolysis device is stored in the hydrogen storage and supply device. Thereby, the hydrogen generated by the water electrolysis device can be effectively utilized at a hydrogen demand destination as needed.

[0018] In the deposit removal system according to the present invention, It is preferable to further include an oxygen storage and supply device that stores the oxygen and supplies the stored oxygen to the pressure wave generator and to the combustion furnace.

[0019] According to the deposit removal system of this configuration, the oxygen generated by the water electrolysis device is stored in the oxygen storage and supply device. The oxygen stored in the oxygen storage and supply device is supplied to the pressure wave generator. As a result, the combustion of the combustible gas in the pressure wave generator can be promoted without separately procuring the oxidant gas (oxygen gas) from outside the facility. Further, the oxygen stored in the oxygen storage and supply device is supplied to the combustion furnace. As a result, the amount of the supporting combustion gas relatively increases in the combustion furnace, so that not only the combustion in the combustion furnace is stabilized, but also the amount of unburned gas can be reduced.

[0020] In the deposit removal system according to the present invention, it is preferable to further include a carbon dioxide recovery device that recovers carbon dioxide from the biogas.

[0021] According to the deposit removal system of this configuration, since carbon dioxide is recovered from the biogas by the carbon dioxide recovery device, the amount of carbon dioxide emissions in the combustion facility can be reduced, and the recovered carbon dioxide can be effectively utilized.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0023] Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings below.

[0024] 〔First Embodiment〕 <Overall Configuration> FIG. 1 is a block diagram showing a schematic configuration of a deposit removal system 15A in a combustion facility 1 according to the first embodiment. The deposit removal system 15A shown in FIG. 1 mainly includes a power generation facility 21, a water electrolysis device 22, a hydrogen storage and supply device 23, an oxygen storage and supply device 24, a fermentation device 25, a biogas storage and supply device 26, and a pressure wave generator 30.

[0025] In FIG. 1, the combustion facility 1 includes, for example, a combustion furnace 2 that burns combustibles such as waste such as municipal waste and biomass fuel, and an exhaust gas treatment facility 10 that treats exhaust gas generated by the combustion in the combustion furnace 2.

[0026] <Combustion Furnace> The type of the combustion furnace 2 is not limited as long as it can burn combustibles, and examples thereof include a stoker-type combustion furnace and a fluidized bed combustion furnace.

[0027] A stoker-type combustion furnace is a type of combustion furnace that moves a stoker arranged inside the furnace, sends combustion air from below the stoker, and dries, burns, and after-burns the material to be burned. Here, examples of stokers include a stepped stoker and a traveling stoker. The stepped stoker has a movable fire grate and a fixed fire grate alternately arranged in a stepped manner, and a drying stoker forming a drying stage, a combustion stoker forming a combustion stage, and a post-combustion stoker forming a post-combustion stage are sequentially divided from the upstream side to the downstream side in the direction of the material to be burned feeding. On the other hand, the traveling stoker is configured by winding and mounting an annular fire grate body in which a plurality of fire grates are annularly connected to each other rotatably on driving wheels and driven wheels arranged at a predetermined interval in the direction of moving the material to be burned in the furnace. In the traveling stoker, the annular fire grate body is driven to perform a circular motion, and the material to be burned from the fuel feeder received by the annular fire grate body is burned on the annular fire grate body while being moved. A fluidized bed combustion furnace is a type of combustion furnace that dispersedly supplies pressurized air from below a particle layer such as silica sand, fluidizes the heat-stored silica sand, etc., and burns the material to be burned therein.

[0028] <Exhaust gas treatment facility> The exhaust gas treatment facility 10 includes a boiler 3, a desuperheating tower 4, a dust collector 5, a denitration device 6, an induced draft fan 7, and a chimney 8, which are arranged in order from the upstream side to the downstream side of the exhaust gas flow path. In the exhaust gas treatment facility 10, the exhaust gas from the combustion furnace 2 is sequentially sent to the boiler 3, the desuperheating tower 4, the dust collector 5, and the denitration device 6 by the suction action of the induced draft fan 7. The exhaust gas is used for heat exchange in the boiler 3 and then cooled to a predetermined temperature in the desuperheating tower 4 before being sent to the dust collector 5. The exhaust gas from which dust has been removed by the dust collector 5 is sent to the denitration device 6. The exhaust gas denitrified by the denitration device 6 is discharged to the outside of the system through the chimney 8 by the induced draft fan 7.

[0029] <Boiler> The boiler 3 is provided with a heat exchange section 35 (see Fig. 7) that exchanges heat with the exhaust gas discharged from the combustion furnace 2. The heat exchange section 35 is formed by a collection of a large number of heat transfer tubes 33 (see Fig. 7) for heat exchange, and is configured to generate steam (superheated steam) by heat exchange between the water flowing through the heat transfer tubes 33 and the exhaust gas flowing outside the heat transfer tubes 33.

[0030] <Power generation facility> The power generation facility 21 shown in Fig. 1 generates electricity using the heat obtained in the heat exchange section 35 of the boiler 3, and also generates electricity using the biogas obtained in the fermentation device 25. That is, the power generation facility 21 is provided with a steam turbine 41 and a generator 42, and is configured to rotate the steam turbine 41 with the superheated steam from the boiler 3 and generate electricity with the generator 42 that is connected to the steam turbine 41 so as to be able to transmit rotational power. Further, the power generation facility 21 is further provided with a gas engine 43 and a generator 44, and is configured to drive the generator 44 with the gas engine 43 using the biogas (flammable gas) from the fermentation device 25 as fuel to generate electricity. The generators 42 and 44 supply the generated power to the water electrolysis device 22, and also supply it to the power demand destination and the power storage device.

[0031] <Water electrolysis device> The water electrolysis device 22 receives the supply of power from the generators 42 and 44 and electrolyzes water to generate hydrogen gas and oxygen gas. Although a detailed description by illustration of the water electrolysis device 22 is omitted, for example, it includes a water tank for storing water, a diaphragm disposed inside the water tank so as to partition the inside of the water tank into a first chamber and a second chamber, having gas barrier properties and ion permeability, an anode disposed in the first chamber, and a cathode disposed in the second chamber, and is configured to generate oxygen gas on the anode side and hydrogen gas on the cathode side simultaneously by passing an electric current between the anode and the cathode. Note that as the water to be electrolyzed in the water electrolysis device 22, water supplied from a water supply source outside the combustion facility 1 may be used, but for example, by using drain water discharged from the steam turbine 41, drain water discharged from the desuperheating tower 4, etc., hydrogen gas and oxygen gas can be generated economically.

[0032] <Hydrogen storage and supply device> A hydrogen storage and supply device 23 is connected to the water electrolysis device 22 so as to be able to supply the generated hydrogen gas. The hydrogen storage and supply device 23 stores the hydrogen gas supplied from the water electrolysis device 22 and supplies the stored hydrogen gas to the hydrogen demand destination. Although detailed description by illustration is omitted for the hydrogen storage and supply device 23, for example, a device including a hydrogen gas tank, a booster, and a pressure reducing valve, stores the hydrogen gas supplied from the water electrolysis device 22 in the hydrogen gas tank in a pressurized state through the booster, and reduces the pressure of the compressed hydrogen gas stored in the hydrogen gas tank to a predetermined pressure with the pressure reducing valve and then supplies it to the hydrogen demand destination. As another hydrogen storage and supply device 23, there is one configured such that a hydrogen storage alloy absorbs and holds hydrogen gas in a hydrogen storage alloy tank. Note that, as a form of the hydrogen storage and supply device 23, for example, components (such as a hydrogen gas tank, a booster, and a pressure reducing valve) may be housed in a container and packaged so as to be transportable by a vehicle or the like (the same applies to the oxygen storage and supply device 24 described later).

[0033] <Oxygen storage and supply device> An oxygen storage and supply device 24 is connected to the water electrolysis device 22 so as to be able to supply the generated oxygen gas. The oxygen storage and supply device 24 stores the oxygen gas supplied from the water electrolysis device 22 and supplies the stored oxygen gas to the pressure wave generator 30 and also to the combustion furnace 2. Although detailed description by illustration is omitted for the oxygen storage and supply device 24, for example, a device including an oxygen gas tank, a booster, and a pressure reducing valve, stores the oxygen gas supplied from the water electrolysis device 22 in the oxygen gas tank in a pressurized state through the booster, and reduces the pressure of the compressed oxygen gas stored in the oxygen gas tank to a predetermined pressure with the pressure reducing valve and then supplies it to the pressure wave generator 30 and the combustion furnace 2.

[0034] <Fermentation device> The fermentation device 25 includes a fermentation tank 25a for storing a fermentation broth obtained by fermenting biomass (biologically derived organic resources), and a biomass supply unit 25b for supplying biomass to the fermentation tank 25a. Here, examples of the biomass supplied from the biomass supply unit 25b to the fermentation tank 25a include organic wastes such as food waste, manure, sludge, food processing residues, livestock waste, waste oil, animal fats, and crop residues.

[0035] The fermentation tank 25a generates biogas containing methane and the like by fermenting (anaerobic fermentation) biomass such as organic waste, and performs a solubilization process by hydrolytic bacteria and acid-producing bacteria, and a methane fermentation process by methane-producing bacteria. Examples of the fermentation tank 25a include a single-tank type fermentation tank that performs the solubilization process and the methane fermentation process in a single tank, a plug flow type fermentation tank that performs the solubilization process and the methane fermentation process while flowing the biomass horizontally, and a two-stage fermentation tank including an acid fermentation tank that performs the solubilization process in the front stage and a methane fermentation tank that performs the methane fermentation process in the subsequent stage of the acid fermentation tank. The biogas generated in the fermentation tank 25a mainly contains methane gas and carbon dioxide gas, and the methane concentration in the biogas is about 50 to 60 vol%.

[0036] Although a detailed description of the biomass supply unit 25b is omitted in the drawings, it is configured to include a pressure pump for pumping organic waste, a control valve for controlling the pumping amount and pumping pressure, a biomass supply pipe connecting the pressure pump and the fermentation tank, and the like. In the previous stage of the biomass supply unit 25b, the raw organic waste is subjected to treatments such as homogenization of the raw material by removing foreign substances with a pretreatment facility (not shown) and adjustment to a moisture content suitable for methane fermentation. The organic waste subjected to such pretreatment is supplied to the fermentation tank 25a by the biomass supply unit 25b.

[0037] <Biogas Storage and Supply Device> The fermentation tank 25a is connected to a biogas storage and supply device 26 so as to be able to supply the generated biogas. The biogas storage and supply device 26 stores the biogas supplied from the fermentation tank 25a and supplies the stored biogas to the pressure wave generator 30. Although a detailed description with reference to the drawings is omitted for the biogas storage and supply device 26, for example, it includes a biogas tank, a booster, and a pressure reducing valve, stores the biogas supplied from the fermentation tank 25a in the biogas tank in a pressurized state through the booster, and after reducing the pressure of the biogas stored in the biogas tank to a predetermined pressure with the pressure reducing valve, supplies it to the pressure wave generator 30.

[0038] <Pressure wave generator> Figure 7 is a system configuration diagram of the drive control of the pressure wave generator 30. As shown in Figure 7, the pressure wave generator 30 is arranged outside the side wall 32 that constitutes the exhaust gas flow path 31 of the boiler 3. In the exhaust gas flow path 31, a heat exchange section 35 is arranged, which is composed of a plurality of heat transfer tube groups 34 formed by providing a plurality of rows of a plurality of heat transfer tubes 33 arranged horizontally in the vertical direction of the boiler 3. In the heat exchange section 35, a space with a predetermined width is provided between the upper heat transfer tube group 34 and the lower heat transfer tube group 34, and a connection duct 36 is projected from the side wall 32 in a communicating state with this space. The pressure wave generator 30 is attached to the connection duct 36 via a nozzle body 37. The pressure wave generator 30 includes a container 51, a lid body 52, a switching mechanism 53, and a sealing body supply mechanism 55.

[0039] In the pressure wave generator 30, when the direction toward the side wall 32 is defined as "front", the front side of the container 51 is open, while the rear side is closed by the end wall portion 51a. The lid body 52 is provided corresponding to the opening provided on the front side of the container 51, and is disposed on the front side of the container-side flange portion 51b so as to face the container-side flange portion 51b formed around the opening of the container 51, and has an opening corresponding to the opening of the container 51. The switching mechanism 53 switches between a sealing body clamping state and a non-sealing body clamping state. Here, the sealing body clamping state means a state in which the container-side flange portion 51b is moved forward, and the strip-shaped sealing body 60 located between the lid body 52 and the container-side flange portion 51b is clamped by the container-side flange portion 51b and the lid body 52. Further, the non-sealing body clamping state means a state in which the container-side flange portion 51b is moved backward and the sealing body 60 located between the lid body 52 and the container-side flange portion 51b is not clamped by the container-side flange portion 51b and the lid body 52. The sealing body supply mechanism 55 supplies the sealing body 60 to the opening of the container 51 when switched to the non-sealing body clamping state by the switching mechanism 53.

[0040] Next, the gas supply means 65 for supplying combustion gases such as combustible gas and oxidant gas necessary for combustion to the container 51 of the pressure wave generator 30 will be described.

[0041] One end side of the main supply pipeline 70 is connected to the end wall portion 51a of the container 51. One end sides of the first branch pipeline 71 and the second branch pipeline 72 are connected to the other end side of the main supply pipeline 70. The other end side of the first branch pipeline 71 is connected to the combustible gas storage supply device 20. Here, the combustible gas storage supply device 20 is a device that stores and supplies combustible gas, and generically refers to the biogas storage supply device 26 and the methane storage supply device 92 described later. In the first embodiment, the biogas storage supply device 26 is used as the combustible gas storage supply device 20. On the other hand, the other end side of the second branch pipeline 72 is connected to the oxygen storage supply device 24.

[0042] In the middle of the main supply pipe 70, a gas main shut-off valve 75 for opening and closing the main supply pipe 70 is interposed. In the middle of the first branch pipe 71, a combustible gas supply valve 76 for opening and closing the first branch pipe 71 is interposed. In the middle of the second branch pipe 72, an oxidant gas supply valve 77 for opening and closing the second branch pipe 72 is interposed. A pressure gauge 78 is connected to a portion between the first branch pipe 71 and the second branch pipe 72 in the main supply pipe 70.

[0043] A glow plug 79 is attached to the end wall portion 51a of the container 51 via a plug protection member (not shown). In such a configuration, by energizing the glow plug 79, the mixed gas inside the container 51 can be ignited. Further, most of the pressure waves generated by the combustion and explosion of the mixed gas are blocked by the plug protection member, so that the glow plug 79 can be protected and the life of the glow plug 79 can be significantly extended.

[0044] In FIG. 7, the control device 80 is mainly composed of a microcomputer. By reading the measured value from the pressure gauge 78 and executing a predetermined program, it controls the opening and closing and valve opening degrees of the various valves 75 to 77, and controls the energization to the glow plug 79.

[0045] In the deposit removal system 15A in the combustion facility 1 configured as described above, each process of an exhaust gas treatment process, a power generation process, a water electrolysis process, a hydrogen storage process, an oxygen storage process, a fermentation process, a biogas storage process, a biogas supply process (combustible gas supply process), an oxygen gas supply process, and an ignition process (pressure wave generation process) is performed.

[0046] <Exhaust gas treatment process> As shown in Fig. 1, the exhaust gas treatment process is carried out by the exhaust gas from the combustion furnace 2 being sequentially sent into the boiler 3, the desuperheating tower 4, the dust collector 5 and the denitration device 6 by the suction action of the suction fan 7. That is, after the exhaust gas is used for heat exchange in the boiler 3, it is cooled to a predetermined temperature in the desuperheating tower 4 and then sent into the dust collector 5 for dust removal treatment, and then sent into the denitration device 6 for denitration treatment. The denitrated exhaust gas is discharged outside the system by the suction fan 7 through the chimney 8.

[0047] <Power generation process> The power generation process is carried out by supplying the superheated steam from the boiler 3 to the power generation facility 21 and by supplying the biogas generated in the fermentation device 25 to the power generation facility 21. That is, in the power generation facility 21, the superheated steam from the boiler 3 is supplied to the steam turbine 41, the steam turbine 41 is rotated by the superheated steam, and power generation is carried out by the generator 42 which is connected to the steam turbine 41 so as to be able to transmit rotational power. Also, the biogas (flammable gas) from the fermentation device 25 is used as fuel to drive the generator 44 by the gas engine 43 for power generation. The electric power generated by the generators 42 and 44 is supplied to the water electrolysis device 22 and also supplied to the power demand side and the power storage device.

[0048] <Water electrolysis process> The water electrolysis process is carried out by electrolyzing water in the water electrolysis device 22 with the electric power generated in the power generation process. Thus, the hydrogen gas and oxygen gas obtained by the electrolysis of water are generated without using the electric power generated by separately using fossil fuels and without accompanying new carbon dioxide emissions, so that it can contribute to carbon dioxide reduction.

[0049] <Hydrogen storage process> In the water electrolysis process, the hydrogen gas generated by the electrolysis of water is supplied to the hydrogen storage supply device 23 for storage. For example, when the hydrogen storage supply device 23 includes a hydrogen gas tank and a booster, the hydrogen gas supplied from the water electrolysis device 22 is stored in the hydrogen gas tank in a pressurized state through the booster.

[0050] <Oxygen storage process> In the water electrolysis process, the oxygen gas generated by the electrolysis of water is supplied to the oxygen storage and supply device 24 and stored. For example, when the oxygen storage and supply device 24 includes an oxygen gas tank and a booster, the oxygen gas supplied from the water electrolysis device 22 is stored in the oxygen gas tank in a pressurized state through the booster.

[0051] <Fermentation process> The fermentation process is carried out by anaerobically fermenting biomass such as organic waste, and includes a solubilization process by hydrolysis bacteria and acid-producing bacteria, and a methane fermentation process by methane-producing bacteria. In this example, in this fermentation process, biogas with a methane concentration of about 50 vol% is generated.

[0052] <Biogas storage process> The biogas generated in the biogas storage process is supplied to the biogas storage and supply device 26 and stored. For example, when the biogas storage and supply device 26 includes a biogas tank and a booster, the biogas supplied from the fermentation tank 25a is stored in the biogas tank in a pressurized state through the booster.

[0053] In carrying out the following biogas supply process (flammable gas supply process) and oxygen gas supply process, as shown in FIG. 7, in the pressure wave generator 30, with the sealing body 60 positioned between the lid body 52 and the container side flange portion 51b, the container 51 is moved forward along the pipe axis. As a result, the sealing body 60 positioned between the lid body 52 and the container side flange portion 51b is clamped by the container side flange portion 51b and the lid body 52 in a state where the opening of the container 51 is closed, resulting in a sealing body clamping state.

[0054] <Biogas supply process (flammable gas supply process)> The control device 80 shown in FIG. 7 transmits a valve closing signal to the oxidant gas supply valve 77 to close the oxidant gas supply valve 77, while transmitting a valve opening signal to each of the main gas shut-off valve 75 and the combustible gas supply valve 76. As a result, each valve of the main gas shut-off valve 75 and the combustible gas supply valve 76 is opened, and biogas (methane concentration of about 50 vol%) reduced to a predetermined pressure by a pressure reducing valve (not shown) from the combustible gas storage supply device 20 (biogas storage supply device 26) is supplied to the container 51 through the first branch pipeline 71 and the main supply pipeline 70.

[0055] After a predetermined time has elapsed, the control device 80 transmits a valve closing signal to the combustible gas supply valve 76. As a result, the combustible gas supply valve 76 is closed. In this way, when the main gas shut-off valve 75 is open and the combustible gas supply valve 76 is closed, the pressure from the upstream side of the combustible gas supply valve 76 in the first branch pipeline 71 does not act on the pressure gauge 78 due to the closure of the combustible gas supply valve 76, and only the pressure from the container 51 side due to the opening of the main gas shut-off valve 75 acts on the pressure gauge 78, enabling the pressure inside the container 51 to be accurately measured.

[0056] Based on the measured value of the pressure gauge 78, the control device 80 fills the container 51 with biogas multiple times so that the pressure inside the container 51 is equal to or higher than the target value (for example, 0.4 MPa) and the pressure inside the container 51 is equal to or lower than the upper limit value (for example, 0.44 MPa, which is 1.1 times the target value (0.4 MPa)). That is, if the measured value of the pressure gauge 78 is not equal to or higher than the target value, the combustible gas supply valve 76 is opened to supply biogas to the container 51, and then the combustible gas supply valve 76 is closed, and the pressure is measured by the pressure gauge 78. If the measured value at this time is still not equal to or higher than the target value, the operation of opening the combustible gas supply valve 76 to supply biogas to the container 51 is repeated. As a result, with the main gas shut-off valve 75 open and the combustible gas supply valve 76 closed, that is, when only the pressure inside the container 51 acts on the pressure gauge 78, the actual pressure value inside the container 51 becomes equal to or higher than the target value.

[0057] Thus, when the actual pressure value in the container 51 is equal to or higher than the target value and the actual pressure value in the container 51 is equal to or lower than the upper limit value, that is, when the actual pressure value in the container 51 is close to the target value, following the biogas supply process, an oxygen gas supply process is carried out.

[0058] <Oxygen gas supply process> The control device 80 transmits a valve closing signal to the combustible gas supply valve 76 to keep the combustible gas supply valve 76 closed, while transmitting a valve opening signal to the oxidant gas supply valve 77. As a result, the oxidant gas supply valve 77 is opened, and oxygen gas reduced to a predetermined pressure by a pressure reducing valve (not shown) from the oxygen storage supply device 24 is supplied to the container 51 via the second branch pipe 72 and the main supply pipe 70.

[0059] After a predetermined time has elapsed, the control device 80 transmits a valve closing signal to the oxidant gas supply valve 77. As a result, the oxidant gas supply valve 77 is closed. In this way, with the gas main shut-off valve 75 open and the oxidant gas supply valve 77 closed, the pressure from the upstream side of the oxidant gas supply valve 77 in the second branch pipe 72 does not act on the pressure gauge 78 due to the closure of the oxidant gas supply valve 77, and only the pressure from the container 51 side due to the opening of the gas main shut-off valve 75 acts on the pressure gauge 78, enabling the pressure in the container 51 to be accurately measured.

[0060] Based on the measured value of the pressure gauge 78, the control device 80 fills the oxygen storage and supply device 24 with oxygen gas multiple times so that the pressure in the container 51 is equal to or higher than the target value (e.g., 0.8 MPa) and equal to or lower than the upper limit value (e.g., 0.88 MPa, which is 1.1 times the target value (0.8 MPa)). That is, if the measured value of the pressure gauge 78 is not equal to or higher than the target value, the oxidant gas supply valve 77 is opened to supply oxygen to the container 51, and then the oxidant gas supply valve 77 is closed. If the measured value at this time is still not equal to or higher than the target value, the oxidant gas supply valve 77 is opened to supply oxygen gas to the container 51, and this operation is repeated. As a result, with the main gas shut-off valve 75 open and the oxidant gas supply valve 77 closed, that is, when only the pressure in the container 51 acts on the pressure gauge 78, the actual pressure value in the container 51 becomes equal to or higher than the target value.

[0061] In this way, when the actual pressure value in the container 51 is equal to or higher than the target value and the actual pressure value in the container 51 is equal to or lower than the upper limit value, that is, when the actual pressure value in the container 51 is equal to or higher than the target value and is close to the target value, the oxygen gas supply process is terminated.

[0062] By implementing the above biogas supply process, the container 51 is filled with an amount of biogas that generates a pressure of approximately 0.4 MPa. Also, by implementing the above oxygen gas supply process, an amount of oxygen gas that generates a pressure difference of approximately 0.4 MPa, which causes the pressure in the container 51, which was approximately 0.4 MPa after the implementation of the previous biogas supply process, to rise to approximately 0.8 MPa, is filled into the container 51. In this way, the container 51 is filled with biogas and oxygen gas in a state where they are mixed at a predetermined mixing ratio (in this example, 1:1). Here, since the concentration of methane contained in the biogas is approximately 50 vol%, it is filled in a state where the methane component and the oxygen component are mixed at a predetermined mixing ratio (1:2).

[0063] When implementing the following ignition process in which the mixed gas of biogas and oxygen gas in the container 51 ignites, the control device 80 shown in FIG. 7 sends a valve closing signal to the main gas shut-off valve 75. As a result, the main gas shut-off valve 75 is closed.

[0064] <Ignition process (pressure wave generation process)> The control device 80 starts energizing the glow plug 79 attached to the container 51. As a result, the temperature of the mixed gas in the container 51 is increased by the glow plug 79. When the mixed gas in the container 51 ignites due to the temperature increase of the mixed gas by the glow plug 79, a combustion and explosion occur in which the flame rapidly propagates inside the container 51. The gas inside the container 51 attempts to expand all at once due to the temperature increase caused by the combustion. The pressure inside the container 51, which is a closed space, rapidly increases, and the sealing body 60 that can no longer withstand the pressure is broken into pieces. When the sealing body 60 is broken, high-pressure gas jets out all at once from the opening of the lid body 52, and the pressure is rapidly released. As a result of the rapid release of the pressure, a pressure wave is generated. The generated pressure wave is discharged into the exhaust gas flow path 31 of the boiler 3 through the nozzle body 37 and the connection duct 36. The dust adhering to the heat transfer tubes 33 in the heat exchange section 35 is peeled off and removed by the wind pressure and vibration caused by the pressure wave thus discharged.

[0065] According to the deposit removal system 15A of the first embodiment, the pressure wave generator 30 discharges the pressure wave generated by mixing and burning the biogas containing methane gas generated in the fermentation device 25 and the oxygen gas generated in the water electrolysis device 22 toward the heat exchange section 35. Therefore, in the deposit removal system 15A that uses the pressure wave generated by the combustion of the combustible gas, it is not necessary to separately procure the combustible gas (methane gas) and the oxidant gas (oxygen gas) from outside the facility, and the procurement cost of the combustible gas and the oxidant gas can be reduced.

[0066] Also, according to the deposit removal system 15A of the first embodiment, even if surplus power is generated in the power generation facility 21, the surplus power can be used to generate hydrogen gas and oxygen gas by the water electrolysis device 22, and the generated hydrogen gas and oxygen gas can be stored and effectively utilized in the hydrogen storage supply device 23 and the oxygen storage supply device 24.

[0067] 〔Second Embodiment〕 FIG. 2 is a block diagram showing a schematic configuration of the deposit removal system 15B in the combustion facility 1 according to the second embodiment. In the second embodiment, for components that are the same as or similar to those in the first embodiment (the preceding embodiment), the same reference numerals are used in the drawings and detailed descriptions thereof are omitted. In the following, the description will focus on the parts specific to the second embodiment (the same applies to the third to sixth embodiments described later).

[0068] As shown in FIG. 2, the deposit removal system 15B of the second embodiment is configured by further adding a carbon dioxide recovery device 91 and a methane storage and supply device 92 to the configuration of the deposit removal system 15A of the first embodiment. The carbon dioxide recovery device 91 and the methane storage and supply device 92 are disposed so as to allow gas flow between the biogas storage and supply device 26 and the pressure wave generator 30. Otherwise, it is basically the same as the deposit removal system 15A of the first embodiment.

[0069] <Carbon Dioxide Recovery Device> The carbon dioxide recovery device 91 recovers carbon dioxide from the exhaust gas after treatment such as dust removal treatment in the exhaust gas treatment facility 10, and also recovers carbon dioxide from the biogas from the biogas storage and supply device 26. Examples of the carbon dioxide recovery device 91 include devices using chemical absorption method, membrane separation method, physical absorption method, solid absorption method, etc. The carbon dioxide recovery device 91 using the chemical absorption method uses, for example, an amine absorption liquid, and is configured to chemically bond (react) carbon dioxide in the exhaust gas and carbon dioxide in the biogas with the amine to separate and recover only carbon dioxide. The carbon dioxide recovery device 91 using the membrane separation method is configured to use a solid thin film having a separation function and utilize its permeation selectivity to separate and recover carbon dioxide from the exhaust gas. The carbon dioxide recovery device 91 using the physical absorption method is configured to separate and recover carbon dioxide by dissolving carbon dioxide in the exhaust gas in a liquid. The carbon dioxide recovery device 91 using the solid absorption method uses zeolite, activated carbon, etc. as the adsorbent for physical adsorption, or an inorganic porous material supporting an alkali metal or amines as the adsorbent for chemical adsorption, and is configured to adsorb carbon dioxide in the exhaust gas to the adsorbent for separation and recovery.

[0070] The carbon dioxide recovery device 91 recovers carbon dioxide from the biogas mainly containing methane gas and carbon dioxide gas supplied from the biogas storage and supply device 26, and supplies the recovered carbon dioxide to the carbon dioxide demand destination. Further, the carbon dioxide recovery device 91 supplies the biogas mainly containing methane gas (hereinafter referred to as "biogas-derived methane gas") after recovering carbon dioxide to the methane storage and supply device 92.

[0071] <Methane Storage and Supply Device> The methane storage and supply device 92 stores the biogas-derived methane gas supplied from the carbon dioxide recovery device 91, and supplies the stored biogas-derived methane gas to the pressure wave generator 30. Although a detailed description with reference to the drawings is omitted, examples of the methane storage and supply device 92 include those equipped with a methane gas tank, a booster, and a pressure reducing valve. The biogas-derived methane gas supplied from the carbon dioxide recovery device 91 is stored in the methane gas tank in a pressurized state through the booster, and the biogas-derived methane gas stored in the methane gas tank is supplied to the pressure wave generator 30 after being depressurized to a predetermined pressure by the pressure reducing valve.

[0072] In the deposit removal system 15B of the second embodiment configured as described above, a carbon dioxide recovery step, a biogas-derived methane gas storage step, and a biogas-derived methane gas supply step that are not performed in the deposit removal system 15A of the first embodiment are respectively carried out.

[0073] <Carbon dioxide recovery step> As shown in FIG. 2, in the carbon dioxide recovery step, part or all of the exhaust gas discharged from the chimney 8 after being subjected to dust removal treatment or the like in the exhaust gas treatment facility 10 is introduced into the carbon dioxide recovery device 91. For example, it is introduced into an absorption tower containing an amine-based absorbent and brought into contact with the absorbent to absorb the carbon dioxide contained in the exhaust gas. The absorbent that has absorbed carbon dioxide is sent from the absorption tower to a regeneration tower, and carbon dioxide is dissipated as carbon dioxide gas from the absorbent in the regeneration tower and recovered. Also, in the carbon dioxide recovery step, a biogas mainly containing methane gas and carbon dioxide gas from the biogas storage and supply device 26 is introduced into the carbon dioxide recovery device 91 in a system separate from the carbon dioxide recovery treatment for the exhaust gas, and the carbon dioxide (carbon dioxide gas) contained in the biogas is recovered in the same manner as the carbon dioxide recovery treatment for the exhaust gas. The carbon dioxide recovered in the carbon dioxide recovery device 91 is supplied to the carbon dioxide demand destination.

[0074] <Biogas-derived methane gas storage step> After carbon dioxide is recovered in the carbon dioxide recovery process, the biogas (methane gas derived from biogas) is supplied to the methane storage and supply device 92 and stored. For example, when the methane storage and supply device 92 includes a methane gas tank and a booster, the methane gas derived from biogas is stored in the methane storage and supply device in a pressurized state through the booster. In this example, the methane concentration in the methane gas derived from biogas is about 80 vol%.

[0075] <Biogas-derived Methane Gas Supply Process (Combustible Gas Supply Process)> In the second embodiment, the methane storage and supply device 92 is used as the combustible gas storage and supply device 20 in FIG. 7. The control device 80 shown in FIG. 7 transmits a valve closing signal to the oxidant gas supply valve 77 to keep the oxidant gas supply valve 77 closed, while transmitting a valve opening signal to each of the gas main shut-off valve 75 and the combustible gas supply valve 76. As a result, the valves of the gas main shut-off valve 75 and the combustible gas supply valve 76 are opened, and the methane gas derived from biogas decompressed to a predetermined pressure by a decompression valve (not shown) from the combustible gas storage and supply device 20 (methane storage and supply device 92) is supplied to the container 51 through the first branch pipeline 71 and the main supply pipeline 70.

[0076] In the biogas-derived methane gas supply process, the control device 80, based on the measured value of the pressure gauge 78, fills the biogas-derived methane gas from the combustible gas storage and supply device 20 (methane storage and supply device 92) multiple times in the same manner as in the biogas supply process so that the pressure in the container 51 is equal to or higher than the target value (for example, 0.3 MPa) and the pressure in the container 51 is equal to or lower than the upper limit value (for example, 0.33 MPa which is 1.1 times the target value (0.3 MPa)). As a result, when the actual pressure value in the container 51 is equal to or higher than the target value and the actual pressure value in the container 51 is equal to or lower than the upper limit value, that is, when the actual pressure value in the container 51 is close to the target value, an oxygen gas supply process similar to the oxygen gas supply process is carried out following the biogas-derived methane gas supply process.

[0077] <Oxygen Gas Supply Process> The control device 80 transmits a valve closing signal to the combustible gas supply valve 76 to close the combustible gas supply valve 76, while transmitting a valve opening signal to the oxidant gas supply valve 77. As a result, the oxidant gas supply valve 77 is opened, and oxygen gas reduced to a predetermined pressure by a pressure reducing valve (not shown) from the oxygen storage and supply device 24 is supplied to the container 51 via the second branch pipeline 72 and the main supply pipeline 70.

[0078] In the oxygen gas supply process, based on the measured value of the pressure gauge 78, the control device 80 fills the oxygen gas from the oxygen storage and supply device 24 multiple times in the same manner as in the oxygen gas supply process so that the pressure in the container 51 is equal to or higher than the target value (for example, 0.8 MPa) and the pressure in the container 51 is equal to or lower than the upper limit value (for example, 0.88 MPa which is 1.1 times the target value (0.8 MPa)). Thus, when the actual pressure value in the container 51 is equal to or higher than the target value and the actual pressure value in the container 51 is equal to or lower than the upper limit value, that is, when the actual pressure value in the container 51 is equal to or higher than the target value and is close to the target value, the oxygen gas supply process is terminated.

[0079] By implementing the above-mentioned biogas-derived methane gas supply process, the container 51 is filled with an amount of biogas-derived methane gas that generates a pressure of about 0.3 MPa in the container 51. Further, by implementing the above-mentioned oxygen gas supply process, an amount of oxygen that generates a pressure difference of about 0.5 MPa, which causes the pressure in the container 51, which was about 0.3 MPa in the implementation of the previous biogas-derived methane gas supply process, to rise to about 0.8 MPa, is filled into the container 51. Thus, the container 51 is filled with a state in which biogas-derived methane gas and oxygen gas are mixed at a predetermined mixing ratio (in this example, 3:5). Here, since the concentration of methane contained in the biogas-derived methane gas is about 80 vol%, it is filled in a state in which the methane component and the oxygen component are mixed at a predetermined mixing ratio (about 1:2).

[0080] Then, in the same manner as in the ignition process (pressure wave generation process), by igniting the mixed gas in the container 51 to generate a pressure wave, the dust adhering to the heat transfer tube 33 in the heat exchange section 35 can be peeled off and removed.

[0081] Even with the deposit removal system 15B of the second embodiment, it is not necessary to separately procure the combustible gas (methane gas) and the oxidant gas (oxygen gas) from outside the facility, and the procurement cost of the combustible gas and the oxidant gas can be reduced. Further, according to the deposit removal system 15B of the second embodiment, since carbon dioxide is recovered from the exhaust gas by the carbon dioxide recovery device, the amount of carbon dioxide emissions in the combustion facility can be reduced, and the recovered carbon dioxide can be effectively utilized.

[0082] Also, in the deposit removal system 15B of the second embodiment, carbon dioxide is recovered and concentrated from the biogas supplied from the biogas storage and supply device 26 by the carbon dioxide recovery device 91, so that the methane concentration in the methane gas derived from biogas increases from 50 vol% to 80 vol%. Therefore, in the deposit removal system 15B of the second embodiment, when the power of the pressure wave generated by the pressure wave generator 30 is set to be the same as that of the deposit removal system 15A of the first embodiment, the gas supply amount of the methane gas derived from biogas supplied to the pressure wave generator 30 can be reduced. On the other hand, in the deposit removal system 15B of the second embodiment, when the gas supply amount of the methane gas derived from biogas supplied to the pressure wave generator 30 is set to be the same as that of the deposit removal system 15A of the first embodiment, the power of the pressure wave generated by the pressure wave generator 30 can be increased.

[0083] 〔Third Embodiment〕 FIG. 3 is a block diagram showing a schematic configuration of a deposit removal system 15C in a combustion facility 1 according to the third embodiment. As shown in FIG. 3, in the deposit removal system 15C of the third embodiment, a reduction device 93 and a methane storage and supply device 92 are disposed so as to allow gas to flow between the biogas storage and supply device 26 and the pressure wave generator 30.

[0084] <Reduction Device> The reduction device 93 is connected so that biogas can be supplied from the biogas storage and supply device 26. The biogas supplied from the biogas storage and supply device 26 to the reduction device 93 contains methane gas and carbon dioxide. In the reduction device 93, carbon dioxide in the biogas is reduced to methane with hydrogen gas supplied from the hydrogen storage and supply device 23 (carbon dioxide reduction step).

[0085] Examples of the reduction device 93 include those configured with a reaction tower filled with a catalyst suitable for the reduction reaction from carbon dioxide to methane inside. Here, as the catalyst, for example, a catalyst in which at least one metal selected from nickel, ruthenium, and rhodium is supported on a heat-resistant inorganic oxide carrier such as alumina is used. Preferably, a ruthenium catalyst in which ruthenium is supported on a porous alumina carrier is used. In this case, since the catalyst exhibits sufficient methanation activity at about 250°C to 300°C, it is advisable to adjust the temperature by temperature adjustment means (not shown) so that the reaction temperature in the reaction tower is about 250°C to 300°C.

[0086] <Methane storage and supply device> The methane storage and supply device 92 is supplied with a mixed methane gas containing the methane gas originally contained in the biogas from the biogas storage and supply device 26 and the methane gas generated in the reduction device 93. The methane storage and supply device 92 stores the mixed methane gas and supplies the stored mixed methane gas to the pressure wave generator 30.

[0087] In the deposit removal system 15C of the third embodiment, by performing the same steps as the above-described combustible gas supply step and oxygen gas supply step, the methane component and the oxygen component are filled in a state of being mixed at a predetermined mixing ratio (about 1:2).

[0088] Then, in the same manner as the ignition step (pressure wave generation step), the mixed gas in the container 51 is ignited to generate a pressure wave, whereby the dust attached to the heat transfer tube 33 in the heat exchange section 35 can be peeled off and removed.

[0089] Even with the deposit removal system 15C of the third embodiment, it is not necessary to separately procure the combustible gas (methane) and the oxidant gas (oxygen) from outside the facility, and the procurement cost of the combustible gas and the oxidant gas can be reduced.

[0090] 〔Fourth Embodiment〕 FIG. 4 is a block diagram showing a schematic configuration of a deposit removal system 15D in a combustion facility 1 according to the fourth embodiment. As shown in FIG. 4, the deposit removal system 15D of the fourth embodiment is configured by adding a carbon dioxide recovery device 91 to the configuration of the deposit removal system 15C of the third embodiment. The carbon dioxide recovery device 91 is disposed so as to allow gas to flow between the biogas storage and supply device 26 and the reduction device 93. In the deposit removal system 15D of the fourth embodiment, a part of the carbon dioxide recovered by the carbon dioxide recovery step by the carbon dioxide recovery device 91 is supplied to the reduction device 93, and the remainder is supplied to the carbon dioxide demand destination. Further, the biogas (biogas-derived methane gas) after carbon dioxide is recovered by the carbon dioxide recovery step by the carbon dioxide recovery device 91 is configured to be supplied to the methane storage and supply device 92. Otherwise, it is basically the same as the deposit removal system 15C of the third embodiment.

[0091] <Carbon Dioxide Reduction Step> In the carbon dioxide reduction step, the carbon dioxide recovered in the carbon dioxide recovery device 91 is introduced into the reduction device 93 as carbon dioxide gas, and the hydrogen gas from the hydrogen storage and supply device 23 is introduced into the reduction device 93. The introduced carbon dioxide gas and hydrogen gas are reacted through a catalyst to reduce carbon dioxide to methane with hydrogen gas.

[0092] <Methane Storage Step> In the methane storage process, the methane gas generated in the carbon dioxide reduction process is supplied from the reduction device 93 to the methane storage and supply device 92 and stored, and the biogas (methane gas derived from biogas) after carbon dioxide is recovered in the carbon dioxide recovery process is supplied from the carbon dioxide recovery device 91 to the methane storage and supply device 92 and stored. Then, the mixed methane gas containing the methane gas generated in the carbon dioxide reduction process and the methane gas derived from biogas is supplied from the methane storage and supply device 92 to the pressure wave generator 30.

[0093] Also in the deposit removal system 15D of the fourth embodiment, by performing the same processes as the above-described combustible gas supply process, oxygen gas supply process, and ignition process to ignite the mixed gas in the container 51 and generate a pressure wave, the dust adhering to the heat transfer tube 33 in the heat exchange section 35 can be peeled off and removed.

[0094] Also by the deposit removal system 15D of the fourth embodiment, it is not necessary to separately procure the combustible gas (methane gas) and the oxidant gas (oxygen gas) from outside the facility, and the procurement cost of the combustible gas and the oxidant gas can be reduced. Further, according to the deposit removal system 15D of the fourth embodiment, since carbon dioxide is recovered from the exhaust gas by the carbon dioxide recovery device 91, the amount of carbon dioxide emissions in the combustion facility 1 can be reduced and the recovered carbon dioxide can be effectively utilized.

[0095] Also, in the deposit removal system 15D of the fourth embodiment, carbon dioxide is recovered and concentrated from the biogas supplied from the biogas storage and supply device 26 by the carbon dioxide recovery device 91, so that the methane concentration in the biogas-derived methane gas increases from about 50 vol% to about 80 vol% in this example. The mixed methane gas of the biogas-derived methane gas with increased methane concentration and the methane generated by the reduction device 93 is supplied to the pressure wave generator 30. Therefore, in the deposit removal system 15D of the fourth embodiment, when the power of the pressure wave generated by the pressure wave generator 30 is set to be the same as that of the deposit removal system 15A of the first embodiment, the gas supply amount of the mixed methane gas supplied to the pressure wave generator 30 can be further reduced. On the other hand, in the deposit removal system 15D of the fourth embodiment, when the gas supply amount of the mixed methane gas supplied to the pressure wave generator 30 is set to be the same as that of the deposit removal system 15A of the first embodiment, the power of the pressure wave generated by the pressure wave generator 30 can be further increased.

[0096] 〔Fifth Embodiment〕 FIG. 5 is a block diagram showing a schematic configuration of a deposit removal system 15E in a combustion facility 1 according to the fifth embodiment. As shown in FIG. 5, in the deposit removal system 15E of the fifth embodiment, the fermentation device 25 further includes a gas supply means 25c for supplying hydrogen gas to the fermentation liquid stored in the fermentation tank 25a. In this example, the gas supply means 25c includes a hydrogen storage and supply device 23 and a gas supply pipe 25d for supplying the hydrogen gas stored in the hydrogen storage and supply device 23 into the fermentation liquid stored in the fermentation tank 25a.

[0097] According to the deposit removal system 15E of the fifth embodiment, since the hydrogen gas from the hydrogen storage and supply device 23 is supplied to the fermentation broth in the fermentation tank 25a by the gas supply means 25c, the hydrogen gas supplied by the gas supply means 25c will be contained in the fermentation broth separately from the hydrogen generated by the decomposition of low-molecular organic substances by acid-producing bacteria. Then, using the hydrogen derived from the hydrogen gas supplied by the gas supply means 25c and the carbon dioxide inevitably generated by the decomposition of low-molecular organic substances by acid-producing bacteria as substrates, methane is generated by the CO2 reduction methane production reaction by hydrogenotrophic methanogens. In this way, carbon dioxide can be reduced with hydrogen, and the methane concentration in the biogas can be increased from about 50 vol% to about 80 vol% in this example. Then, the pressure wave generator 30 emits the pressure wave generated by mixing and burning the biogas with an increased methane concentration and the oxygen gas generated by the water electrolysis device 22 toward the heat exchange unit 35. Therefore, it is not necessary to separately procure the combustible gas (methane gas) and the oxidizing agent gas (oxygen gas) from outside the facility, and the procurement cost of the combustible gas and the oxidizing agent gas can be reduced. In particular, since the methane concentration of the biogas used as the combustible gas is increased by the CO2 reduction methane production reaction, the combustibility can be improved, and a high-output pressure wave can be stably generated.

[0098] FIG. 8 is an explanatory diagram of the fermentation tank 25a to which the gas supply means 25c is attached. FIG. 8(a) shows the case where the fermentation tank 25a is a single-tank type, FIG. 8(b) shows the case where the fermentation tank 25a is a plug flow type, and FIG. 8(c) shows the case where the fermentation tank 25a is a two-stage type.

[0099] As shown in Fig. 8(a), in the case of the single-tank fermenter 25a that performs the solubilization step and the methane fermentation step in a single tank, the fermenter 25a has an acid fermentation zone 101 set on the lower side and a methane fermentation zone 102 set on the upper side. In the acid fermentation zone 101, an acid production reaction is carried out in which organic substances are decomposed by acid-producing bacteria into lower organic acids such as butyric acid, propionic acid, and acetic acid. On the other hand, in the methane fermentation zone 102, a methane production reaction is carried out by methane-producing bacteria to produce methane from acetic acid, as well as hydrogen and carbon dioxide. If the hydrogen gas from the gas supply means 25c is supplied to the acid fermentation zone 101, in addition to the hydrogen component by-produced in the acid production reaction carried out in the acid fermentation zone 101, the hydrogen component derived from the hydrogen gas supplied by the gas supply means 25c accumulates and the hydrogen partial pressure rises. As a result, the production reaction of acetic acid may not proceed due to product inhibition, and ultimately the methane production rate may decrease. Therefore, it is preferable that the gas supply means 25c supplies the hydrogen gas from the hydrogen storage and supply device 23 to the methane fermentation zone 102 via the gas supply pipe 25d. Thereby, product inhibition in the acid fermentation zone 101 can be avoided. As a result, in the methane fermentation zone 102, methane gas is generated by the acetic acid decomposition methane production reaction using acetic acid as a substrate, and methane gas is also generated by the CO2 reduction methane production reaction using the hydrogen component and the carbon dioxide component as substrates, and the production efficiency of methane gas can be improved.

[0100] As shown in Fig. 8(b), in the case of the plug-flow fermenter 25a that performs the solubilization step and the methane fermentation step while flowing biomass (organic waste, etc.) in the lateral direction (the direction from left to right in Fig. 8(b)), the fermenter 25a has an acid fermentation zone 101 set on the upstream side in the biomass flow direction and a methane fermentation zone 102 set on the downstream side in the biomass flow direction. For the reasons described above, it is preferable that the gas supply means 25c supplies the hydrogen gas from the hydrogen storage and supply device 23 to the methane fermentation zone 102 via the gas supply pipe 25d.

[0101] As shown in Fig. 8(c), in the case of the two-stage fermenter 25a including an acid fermentation tank 111 that performs a solubilization step in the previous stage and a methane fermentation tank 112 that performs a methane fermentation step in the subsequent stage of the acid fermentation tank 111, it is preferable that the gas supply means 25c supplies hydrogen gas to the methane fermentation tank 112 without supplying hydrogen gas to the acid fermentation tank 111. Thereby, product inhibition can be avoided in the acid fermentation tank 111. As a result, in the methane fermentation tank 112, methane is generated by an acetic acid-decomposing methane production reaction using acetic acid as a substrate, and methane gas is generated by a CO2-reducing methane production reaction using a hydrogen component and a carbon dioxide component as substrates, and the production efficiency of methane gas can be improved.

[0102] 〔Sixth Embodiment〕 Fig. 6 is a block diagram showing a schematic configuration of the deposit removal system 15F in the combustion facility 1 according to the sixth embodiment. As shown in Fig. 6, the deposit removal system 15F of the sixth embodiment is configured by further adding a carbon dioxide recovery device 91 and a methane storage and supply device 92 to the configuration of the deposit removal system 15E of the fifth embodiment. The carbon dioxide recovery device 91 and the methane storage and supply device 92 are disposed so as to allow gas to flow between the biogas storage and supply device 26 and the pressure wave generator 30. Otherwise, it is basically the same as the deposit removal system 15E of the fifth embodiment.

[0103] In the deposit removal system 15F of the sixth embodiment, biogas with an increased methane concentration is stored in the biogas storage and supply device 26 by supplying hydrogen gas from the gas supply means 25c to the fermentation tank 25a. Then, carbon dioxide is recovered and concentrated from the biogas supplied from the biogas storage and supply device 26 by the carbon dioxide recovery device 91, so that the methane concentration in the biogas-derived methane gas is further increased. Therefore, in the deposit removal system 15F of the sixth embodiment, when the power of the pressure wave generated by the pressure wave generator 30 is set to be the same as that of the deposit removal system 15E of the fifth embodiment, the gas supply amount of the biogas-derived methane gas supplied to the pressure wave generator 30 can be reduced. On the other hand, in the deposit removal system 15F of the sixth embodiment, when the gas supply amount of the biogas-derived methane gas supplied to the pressure wave generator 30 is set to be the same as that of the deposit removal system 15E of the fifth embodiment, the power of the pressure wave generated by the pressure wave generator 30 can be further increased.

[0104] As described above, the deposit removal system of the present invention has been described based on a plurality of embodiments. However, the present invention is not limited to the configurations described in the above embodiments, and the configuration can be appropriately changed within the scope not departing from the gist thereof, such as appropriately combining the configurations described in each embodiment.

[0105] In each of the above embodiments, instead of the oxygen storage and supply device 24, an air storage and supply device or a compressor may be provided, and air may be directly supplied from the compressed air tank or the compressor to the pressure wave generator 30, and a pressure wave generated by mixing and burning biogas, biogas-derived methane gas, mixed methane gas, etc. with air may be discharged toward the heat exchange unit 35.

[0106] In each of the above embodiments, an example of using a pressure wave generator 30 is shown in which the pressure inside the container 51 is rapidly increased by the combustion of a mixed gas of a combustible gas and an oxidant gas supplied into the container 51, thereby breaking a seal body 60 that closes the opening of the container 51 to generate a pressure wave, and the generated pressure wave is emitted toward the heat exchange section 35. However, the present invention is not limited to this. As other pressure wave generators that can be used in each of the above embodiments, for example, there is a configuration in which a combustible gas and an oxidant gas are mixed to generate a pressure wave in a detonation wave generation chamber in a violent combustion form, and the pressure waves are sequentially superimposed to generate a detonation wave, and this detonation wave is emitted toward the heat exchange section 35.

Industrial Applicability

[0107] The deposit removal system of the present invention can be used for removing deposits on a heat exchange section that exchanges heat with exhaust gas from a combustion furnace in a combustion facility equipped with a power generation facility.

Explanation of Reference Numerals

[0108] 15A to 15F Deposit removal system 1 Combustion facility 2 Combustion furnace 21 Power generation facility 22 Water electrolysis device 23 Hydrogen storage and supply device 24 Oxygen storage and supply device 25 Fermentation device 30 Pressure wave generator 35 Heat exchange section 91 Carbon dioxide recovery device 93 Reduction device 101 Acid fermentation zone 102 Methane fermentation zone

Claims

1. An adhesion removal system for removing the adhesion adhered to the heat exchange part that exchanges heat with the exhaust gas from the combustion furnace, comprising: a power generation facility that generates electricity by using the heat obtained in the heat exchange part; a water electrolysis device that electrolyzes water with the generated electricity to generate hydrogen gas and oxygen gas; a fermentation device that ferments biomass to generate biogas; a pressure wave generator that mixes and burns the biogas and the oxygen gas to generate a pressure wave and discharges the generated pressure wave toward the heat exchange part; An adhesion removal system comprising the above.

2. An adhesion removal system for removing the adhesion adhered to the heat exchange part that exchanges heat with the exhaust gas from the combustion furnace, comprising: a power generation facility that generates electricity by using the heat obtained in the heat exchange part; a water electrolysis device that electrolyzes water with the generated electricity to generate hydrogen gas and oxygen gas; a fermentation device that ferments biomass to generate biogas; a reduction device that introduces the biogas and the hydrogen gas and reduces carbon dioxide contained in the biogas to methane with the hydrogen gas; a pressure wave generator that mixes and burns the gas containing methane from the reduction device and the oxygen gas or air to generate a pressure wave and discharges the generated pressure wave toward the heat exchange part; An adhesion removal system comprising the above.

3. An adhesion removal system for removing the adhesion adhered to the heat exchange part that exchanges heat with the exhaust gas from the combustion furnace, comprising: a power generation facility that generates electricity by using the heat obtained in the heat exchange part; a water electrolysis device that electrolyzes water with the generated electricity to generate hydrogen gas and oxygen gas; a fermentation device having a fermentation tank for storing the fermentation liquid obtained by fermenting biomass and a gas supply means for supplying the hydrogen gas to the fermentation tank, and generating biogas in the fermentation tank; a pressure wave generator that mixes and burns the biogas and the oxygen gas or air to generate a pressure wave and discharges the generated pressure wave toward the heat exchange part; An adhesion removal system comprising the above.

4. The fermentation tank has an acid fermentation zone and a methane fermentation zone, The adhesion removal system according to claim 3, wherein the gas supply means supplies the hydrogen gas to the methane fermentation zone.

5. The adhesion removal system according to any one of claims 1 to 4, further comprising a hydrogen storage and supply device that stores the hydrogen and supplies the stored hydrogen to a hydrogen demand destination.

6. The deposit removal system according to any one of claims 1 to 4, further comprising an oxygen storage and supply device that stores the oxygen and supplies the stored oxygen to the pressure wave generator and to the combustion furnace.

7. The deposit removal system according to any one of claims 1, 3, and 4, further comprising a carbon dioxide recovery device that recovers carbon dioxide from the biogas.

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