US20240133550A1 - Combustion device and boiler - Google Patents
Combustion device and boiler Download PDFInfo
- Publication number
- US20240133550A1 US20240133550A1 US18/402,857 US202418402857A US2024133550A1 US 20240133550 A1 US20240133550 A1 US 20240133550A1 US 202418402857 A US202418402857 A US 202418402857A US 2024133550 A1 US2024133550 A1 US 2024133550A1
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- United States
- Prior art keywords
- ammonia
- injection nozzle
- injection
- pulverized coal
- flow rate
- Prior art date
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 59
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 407
- 238000002347 injection Methods 0.000 claims abstract description 237
- 239000007924 injection Substances 0.000 claims abstract description 237
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 203
- 239000003245 coal Substances 0.000 claims abstract description 79
- 230000007246 mechanism Effects 0.000 claims abstract description 53
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 55
- 238000010586 diagram Methods 0.000 description 14
- 239000000446 fuel Substances 0.000 description 13
- 239000002344 surface layer Substances 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 238000000354 decomposition reaction Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 238000010248 power generation Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000010344 co-firing Methods 0.000 description 2
- 239000000567 combustion gas Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000006200 vaporizer Substances 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C1/00—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air
- F23C1/12—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air gaseous and pulverulent fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D1/00—Burners for combustion of pulverulent fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
- F23N1/087—Regulating fuel supply conjointly with another medium, e.g. boiler water using mechanical means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C1/00—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air
- F23C1/10—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air liquid and pulverulent fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C99/00—Subject-matter not provided for in other groups of this subclass
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/20—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone
- F23D14/22—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone with separate air and gas feed ducts, e.g. with ducts running parallel or crossing each other
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/48—Nozzles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D17/00—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J7/00—Arrangement of devices for supplying chemicals to fire
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
Definitions
- the present disclosure relates to a combustion device and a boiler.
- the present application claims the benefit of priority based on Japanese Patent Application No. 2021-169141 filed on Oct. 14, 2021, the content of which is incorporated herein.
- Patent Literature 1 discloses a burner that performs co-firing of pulverized coal and ammonia as fuel.
- NOx nitrogen oxides
- An object of the present disclosure is to provide a combustion device and a boiler capable of suppressing emission of nitrogen oxides (NOx).
- a combustion device includes: an ammonia injection nozzle having an injection port facing an internal space of a furnace; a pulverized coal injection nozzle having an injection port facing the internal space of the furnace; an adjustment mechanism that adjusts an injection flow rate of ammonia from the ammonia injection nozzle; and a control device that controls an operation of the adjustment mechanism in such a manner that the injection flow rate of ammonia from the ammonia injection nozzle is higher than an injection flow rate of pulverized coal from the pulverized coal injection nozzle.
- the adjustment mechanism may include a mechanism that adjusts an opening area of the injection port of the ammonia injection nozzle.
- the ammonia injection nozzle may include a plurality of ammonia flow paths
- the adjustment mechanism may include a mechanism that adjusts the number of ammonia flow paths through which ammonia flows among the plurality of ammonia flow paths.
- the boiler of the present disclosure includes the combustion device described above.
- FIG. 1 is a schematic diagram illustrating a boiler according to the present embodiment.
- FIG. 2 is a schematic diagram illustrating a combustion device according to the present embodiment.
- FIG. 3 is a schematic diagram illustrating an adjustment mechanism according to the present embodiment.
- FIG. 4 is a schematic diagram illustrating a state in which the opening area of an injection port of an ammonia injection nozzle according to the present embodiment is smaller than that in the example of FIG. 3 .
- FIG. 5 is a flowchart illustrating an example of a flow of processing performed by a control device according to the present embodiment.
- FIG. 6 is a diagram for explaining a flame formed by the combustion device according to the present embodiment.
- FIG. 7 is a diagram for explaining a flame formed by a combustion device according to a comparative example.
- FIG. 8 is a schematic diagram illustrating a combustion device according to a modification.
- FIG. 9 is a cross-sectional view illustrating the inside of an ammonia injection nozzle according to a modification.
- FIG. 1 is a schematic diagram illustrating a boiler 1 according to the present embodiment. As illustrated in FIG. 1 , the boiler 1 includes a furnace 2 , a flue 3 , and burners 4 .
- the furnace 2 fuel is burnt to generate combustion heat.
- the furnace 2 has a tubular shape such as a rectangular tubular shape extending in the vertical direction.
- high-temperature combustion gas is generated by combustion of fuel.
- a bottom portion of the furnace 2 includes a discharge port 2 a for discharging ash generated by combustion of fuel to the outside.
- the flue 3 is a passage for guiding combustion gas generated in the furnace 2 to the outside as exhaust gas.
- the flue 3 is connected with an upper part of the furnace 2 .
- the flue 3 has a horizontal flue 3 a and a rear flue 3 b .
- the horizontal flue 3 a extends horizontally from the upper part of the furnace 2 .
- the rear flue 3 b extends downward from an end of the horizontal flue 3 a.
- the boiler 1 includes a superheater (not illustrated) installed above or on the furnace 2 .
- a superheater In the superheater, heat is exchanged between combustion heat generated in the furnace 2 and water. As a result of this, water vapor is generated.
- the boiler 1 may also include various devices such as a repeater, a coal economizer, and an air preheater not illustrated in FIG. 1 .
- the burners 4 are provided at a lower wall portion of the furnace 2 .
- a plurality of burners 4 is provided at intervals in the circumferential direction of the furnace 2 .
- the plurality of burners 4 is provided at intervals also in the vertical direction which is the extending direction of the furnace 2 .
- the burners 4 inject ammonia and pulverized coal as fuel into the furnace 2 .
- the fuel injected from the burners 4 burns to form a flame F in the furnace 2 .
- the furnace 2 is provided with an ignition device (not illustrated) that ignites the fuel injected from the burners 4 .
- FIG. 2 is a schematic diagram illustrating a combustion device 100 according to the present embodiment.
- the combustion device 100 includes a burner 4 , an air supply unit 5 , an ammonia tank 6 , an adjustment mechanism 7 , and a control device 8 .
- the burner 4 is attached to a wall portion of the furnace 2 outside the furnace 2 .
- the burner 4 includes an ammonia injection nozzle 41 , an air injection nozzle 42 , and a pulverized coal injection nozzle 43 .
- the ammonia injection nozzle 41 is a nozzle that injects ammonia.
- the air injection nozzle 42 is a nozzle that injects air for combustion.
- the pulverized coal injection nozzle 43 is a nozzle that injects pulverized coal.
- the ammonia injection nozzle 41 , the air injection nozzle 42 , and the pulverized coal injection nozzle 43 each have a cylindrical shape.
- the air injection nozzle 42 is disposed coaxially with the ammonia injection nozzle 41 in such a manner as to surround the ammonia injection nozzle 41 .
- the pulverized coal injection nozzle 43 is disposed coaxially with the air injection nozzle 42 in such a manner as to surround the air injection nozzle 42 .
- the ammonia injection nozzle 41 , the air injection nozzle 42 , and the pulverized coal injection nozzle 43 form a triple cylindrical structure.
- the central axes of the ammonia injection nozzle 41 , the air injection nozzle 42 , and the pulverized coal injection nozzle 43 intersect with the wall portion of the furnace 2 .
- the central axes of the ammonia injection nozzle 41 , the air injection nozzle 42 , and the pulverized coal injection nozzle 43 are substantially orthogonal to the wall portion of the furnace 2 .
- the radial direction of the burner 4 , the axial direction of the burner 4 , and the circumferential direction of the burner 4 are also simply referred to as the radial direction, the axial direction, and the circumferential direction, respectively.
- the furnace 2 side (right side in FIG. 2 ) of the burner 4 is referred to as a distal end side, and the opposite side (left side in FIG. 2 ) of the burner 4 to the furnace 2 side is referred to as a rear end side.
- the ammonia injection nozzle 41 includes a main body 41 a , a supply port 41 b , and an injection port 41 c .
- the main body 41 a has a cylindrical shape.
- the main body 41 a extends along the central axis of the burner 4 .
- the wall thickness, the inner diameter, and the outer diameter of the main body 41 a are substantially constant regardless of the axial position. However, the wall thickness, the inner diameter, and the outer diameter of the main body 41 a may vary depending on the axial position.
- the supply port 41 b that is an opening is included at the rear end of the main body 41 a .
- the supply port 41 b is connected with the ammonia tank 6 .
- the injection port 41 c which is an opening is included at the distal end of the main body 41 a .
- the injection port 41 c faces the internal space of the furnace 2 . That is, the injection port 41 c faces the internal space of the furnace 2 .
- Ammonia is supplied from the ammonia tank 6 into the main body 41 a through the supply port 41 b . As indicated by an arrow A 1 , the ammonia supplied into the main body 41 a flows in the main body 41 a . The ammonia that has passed through the inside of the main body 41 a is injected from the injection port 41 c towards the internal space of the furnace 2 . In this manner, the ammonia injection nozzle 41 is included in such a manner as to face the internal space of the furnace 2 .
- the ammonia tank 6 stores ammonia in liquid form.
- the ammonia stored in the ammonia tank 6 is vaporized by a vaporizer.
- the vaporized ammonia is supplied to the ammonia injection nozzle 41 .
- the air injection nozzle 42 includes a main body 42 a and an injection port 42 b .
- the main body 42 a has a cylindrical shape.
- the main body 42 a is disposed coaxially with the main body 41 a of the ammonia injection nozzle 41 in such a manner as to surround the main body 41 a .
- the main body 42 a has a tapered shape tapered towards the distal end side.
- a supply port (not illustrated) is included at the rear portion of the main body 42 a.
- the supply port of the air injection nozzle 42 is connected with an air supply source (not illustrated).
- the supply port of the air injection nozzle 42 is exposed to the atmosphere as the air supply source.
- the injection port 42 b which is an opening is included at the distal end of the main body 42 a .
- On a radially inner side of the distal end of the main body 42 a the distal end of the main body 41 a of the ammonia injection nozzle 41 is positioned.
- the injection port 42 b is an annular opening between the distal end of the main body 42 a and the distal end of the main body 41 a of the ammonia injection nozzle 41 .
- the injection port 42 b faces the internal space of the furnace 2 . That is, the injection port 42 b faces the internal space of the furnace 2 .
- the air is supplied from the air supply source into the main body 42 a via the supply port (not illustrated). As indicated by an arrow A 2 , the air supplied into the main body 42 a flows in a space between an inner peripheral portion of the main body 42 a and an outer peripheral portion of the main body 41 a of the ammonia injection nozzle 41 . The air having passed through the inside of the main body 42 a is injected from the injection port 42 b towards the internal space of the furnace 2 . In this manner, the air injection nozzle 42 is included in such a manner as to face the internal space of the furnace 2 .
- the pulverized coal injection nozzle 43 includes a main body 43 a and an injection port 43 b .
- the main body 43 a has a cylindrical shape.
- the main body 43 a is disposed coaxially with the main body 42 a of the air injection nozzle 42 in such a manner as to surround the main body 42 a .
- the main body 43 a has a tapered shape tapered towards the distal end side.
- a supply port (not illustrated) is provided at the rear portion of the main body 43 a.
- the supply port of the pulverized coal injection nozzle 43 is connected with a pulverized coal supply source (not illustrated).
- the injection port 43 b which is an opening is included at the distal end of the main body 43 a .
- the axial position of the distal end of the main body 43 a substantially coincides with the axial position of the distal end of the main body 42 a of the air injection nozzle 42 .
- the injection port 43 b is an annular opening between the distal end of the main body 43 a and the distal end of the main body 42 a of the air injection nozzle 42 .
- the injection port 43 b faces the internal space of the furnace 2 . That is, the injection port 43 b faces the internal space of the furnace 2 .
- the pulverized coal is supplied into the main body 43 a from the pulverized coal supply source via the supply port (not illustrated) together with air for conveying the pulverized coal.
- the pulverized coal supplied into the main body 43 a flows, together with the air, in the space between an inner peripheral portion of the main body 43 a and an outer peripheral portion of the main body 42 a of the air injection nozzle 42 .
- the pulverized coal having passed through the inside of the main body 43 a is injected from the injection port 43 b towards the internal space of the furnace 2 .
- the pulverized coal injection nozzle 43 is included in such a manner as to face the internal space of the furnace 2 .
- the air supply unit 5 supplies air for combustion to the flame F formed by the burner 4 from radially outside.
- the air supply unit 5 is disposed in such a manner as to cover a space between the distal end of the burner 4 and the furnace 2 .
- a flow path 51 through which air flows is formed in the air supply unit 5 .
- the flow path 51 is formed in a cylindrical shape coaxial with the burner 4 .
- the flow path 51 is connected with an air supply source (not illustrated).
- An injection port 52 is formed at an end of the flow path 51 on the furnace 2 side.
- air supplied from the air supply source to the air supply unit 5 passes through the flow path 51 and is injected from the injection port 52 towards the internal space of the furnace 2 .
- the injection port 52 faces the internal space of the furnace 2 . That is, the injection port 52 faces the internal space of the furnace 2 .
- the air supply unit 5 is included in such a manner as to face the internal space of the furnace 2 .
- the air injected from the injection port 52 of the air supply unit 5 advances towards the internal space of the furnace 2 while swirling in the circumferential direction.
- the adjustment mechanism 7 is a mechanism for adjusting the injection flow rate of ammonia from the ammonia injection nozzle 41 .
- the injection flow rate of ammonia is the flow rate of ammonia injected from the injection port 41 c of the ammonia injection nozzle 41 .
- the adjustment mechanism 7 adjusts the injection flow rate of ammonia from the ammonia injection nozzle 41 by adjusting the opening area of the injection port 41 c of the ammonia injection nozzle 41 . Details of the adjustment mechanism 7 will be described with reference to FIG. 3 .
- FIG. 3 is a schematic diagram illustrating the adjustment mechanism 7 according to the present embodiment.
- a variable unit 41 d is provided at the distal end of the ammonia injection nozzle 41 .
- the opening area of the injection port 41 c changes.
- the variable unit 41 d includes a plurality of members spaced apart in the circumferential direction, and the shape thereof can be changed in such a manner that each of the members is in an inclined attitude in which a distal end is located radially inward relative to a rear end.
- a variable unit 41 d for example, a structure similar to that of the convergent-divergent nozzles can be adopted.
- the adjustment mechanism 7 includes a drive device 71 .
- the drive device 71 changes the shape of the variable unit 41 d of the ammonia injection nozzle 41 .
- the drive device 71 is provided at the rear end of the variable unit 41 d and includes a power source such as a motor that generates power. Then, the drive device 71 can change the attitude of the variable unit 41 d by rotating the variable unit 41 d about the rear end of the variable unit 41 d .
- the adjustment mechanism 7 can adjust the opening area of the injection port 41 c of the ammonia injection nozzle 41 by changing the shape of the variable unit 41 d of the ammonia injection nozzle 41 by the drive device 71 .
- FIG. 4 is a schematic diagram illustrating a state in which the opening area of the injection port 41 c of the ammonia injection nozzle 41 according to the present embodiment is smaller than that in the example of FIG. 3 .
- the shape of the variable unit 41 d is changed in such a manner that the radial position of the distal end of the variable unit 41 d moves radially inward. Accordingly, the shape of the variable unit 41 d is tapered towards the distal end side.
- the shape of the variable unit 41 d in FIG. 4 is a truncated cone shape. Therefore, the opening area of the injection port 41 c of the ammonia injection nozzle 41 is reduced.
- the adjustment mechanism 7 can adjust the injection flow rate of ammonia from the ammonia injection nozzle 41 by adjusting the opening area of the injection port 41 c of the ammonia injection nozzle 41 . As described above, the adjustment mechanism 7 appropriately achieves adjustment of the injection flow rate of ammonia.
- the control device 8 in FIG. 2 includes a central processing unit (CPU), a ROM in which a program and the like are stored, a RAM as a work area, and others and controls the entire combustion device 100 .
- the control device 8 controls the operation of the adjustment mechanism 7 .
- the control device 8 can adjust the opening area of the injection port 41 c of the ammonia injection nozzle 41 by controlling the drive device 71 of the adjustment mechanism 7 to adjust the injection flow rate of ammonia from the ammonia injection nozzle 41 .
- FIG. 5 is a flowchart illustrating an example of a flow of processing performed by the control device 8 according to the present embodiment.
- the processing flow illustrated in FIG. 5 is repeatedly executed at preset time intervals, for example.
- the processing example of FIG. 5 is merely an example, and the processing performed by the control device 8 is not limited to this example.
- step S 101 the control device 8 acquires the injection flow rate of pulverized coal from the pulverized coal injection nozzle 43 .
- the injection flow rate of pulverized coal is the flow rate of the pulverized coal injected from the injection port 43 b of the pulverized coal injection nozzle 43 .
- the supply amount of air for conveyance supplied to the pulverized coal injection nozzle 43 varies depending on the required combustion amount in the furnace 2 . Accordingly, the injection flow rate of the pulverized coal varies depending on the required combustion amount in the furnace 2 . For example, the injection flow rate of pulverized coal increases as the required combustion amount in the furnace 2 increases. The required combustion amount in the furnace 2 correlates with a required load or a required power generation amount of the boiler 1 .
- the control device 8 acquires the supply amount of air for conveyance, for example, a device that controls the supply amount of the air for conveyance supplied to the pulverized coal injection nozzle 43 . Then, the control device 8 can acquire the injection flow rate of the pulverized coal on the basis of the supply amount of the air for conveyance. The control device 8 may control the supply amount of air for control device supplied to the pulverized coal injection nozzle 43 .
- step S 102 the control device 8 controls the adjustment mechanism 7 in such a manner that the injection flow rate of ammonia is higher than the injection flow rate of pulverized coal.
- the control device 8 controls the drive device 71 of the adjustment mechanism 7 in such a manner that the opening area of the injection port 41 c of the ammonia injection nozzle 41 varies depending on the injection flow rate of pulverized coal. This makes it possible to make the injection flow rate of ammonia to be higher than the injection flow rate of pulverized coal.
- control device 8 controls the adjustment mechanism 7 in consideration of a parameter other than the opening area of the injection port 41 c among parameters that affect the injection flow rate of ammonia.
- the supply amount of ammonia to the ammonia injection nozzle 41 can vary depending on the required combustion amount in the furnace 2 . Therefore, the control device 8 preferably controls the adjustment mechanism 7 on the basis of the supply amount of ammonia to the ammonia injection nozzle 41 in addition to the injection flow rate of pulverized coal. As a result, it is more appropriately achieved that the injection flow rate of ammonia is made higher than the injection flow rate of pulverized coal.
- the control device 8 may cause the opening area of the injection port 41 c of the ammonia injection nozzle 41 to vary depending on a parameter other than the injection flow rate of pulverized coal.
- the control device 8 cause the opening area of the injection port 41 c of the ammonia injection nozzle 41 to vary depending on the required combustion amount in the furnace 2 , the required load of the boiler 1 , or the required power generation amount of the boiler 1 .
- the control device 8 controls the operation of the adjustment mechanism 7 in such a manner that the injection flow rate of ammonia from the ammonia injection nozzle 41 is higher than the injection flow rate of pulverized coal from the pulverized coal injection nozzle 43 .
- the shape of the flame F formed in front of the burner 4 and the phenomenon occurring in the flame F vary.
- the shape of the flame F and a phenomenon occurring in the flame F will be described with reference to FIGS. 6 and 7 .
- FIG. 6 is a diagram for explaining the flame F formed by the combustion device 100 according to the present embodiment. That is, the flame F illustrated in FIG. 6 is a flame of the case where the injection flow rate of ammonia is faster than the injection flow rate of pulverized coal.
- the flame F has an elongated shape extending along the central axis of the burner 4 .
- a flow of air injected from the air supply unit 5 is formed in the vicinity of a surface layer of the flame F, as indicated by broken line arrows A 5 .
- the pulverized coal injected from the pulverized coal injection nozzle 43 is pulled by the flow of air injected from the air supply unit 5 and flows in the vicinity of the surface layer of the flame F. Therefore, the pulverized coal injected from the pulverized coal injection nozzle 43 flows in the vicinity of the surface layer of the flame F along the flow of air indicated by the broken line arrows A 5 as indicated by broken-line arrows A 6 .
- the pulverized coal burns and NOx is generated in a region R 1 in the vicinity of the surface layer of the flame F.
- the region R 1 is a combustion region of the pulverized coal.
- the injection flow rate of ammonia is faster than the injection flow rate of pulverized coal. Therefore, since the ammonia injected from the ammonia injection nozzle 41 is less likely to be pulled by the flow of the air injected from the air supply unit 5 , the ammonia flows through the center of the flame F in the axial direction of the burner 4 as indicated by solid arrows A 7 .
- the direction of a flow of ammonia can actually be various directions; however, the main direction is the axial direction of the burner 4 .
- ammonia (NH 3 ) is decomposed into NH 2 , NH, and N in a region R 2 , where there is less oxygen, on the center side of the flame F.
- the region R 2 is located radially inward with respect to the region R 1 .
- the region R 2 is a decomposition region of ammonia.
- the region R 2 has an elongated shape extending along the central axis of the burner 4 .
- NOx is reduced by NH 2 , NH, and N in a region R 3 on the distal end side of the flame F.
- the region R 3 is positioned on the front side with respect to the region R 2 .
- the region R 3 is a reduction region of NOx.
- FIG. 7 is a diagram for explaining a flame F formed by a combustion device according to a comparative example.
- the injection flow rate of ammonia is lower than the injection flow rate of pulverized coal. That is, the flame F illustrated in FIG. 7 is a flame of a case where the injection flow rate of ammonia is lower than the injection flow rate of pulverized coal.
- the flame F has a shape expanded in the radial direction as compared with the example of FIG. 6 .
- air injected from an air supply unit 5 and pulverized coal injected from a pulverized coal injection nozzle 43 flow in the vicinity of a surface layer of the flame F.
- the pulverized coal burns, and NOx is generated.
- the injection flow rate of ammonia is lower than the injection flow rate of pulverized coal. Therefore, the ammonia injected from an ammonia injection nozzle 41 is easily pulled by a flow of the air injected from the air supply unit 5 . Therefore, most of the ammonia injected from the ammonia injection nozzle 41 flows along the flow of the air indicated by the broken line arrows A 5 as indicated by solid line arrows A 7 . As a result, ammonia burns, and NOx is generated in a region R 4 , where there is a large amount of oxygen, away from the center of the flame F towards the surface layer side.
- the region R 4 is a combustion region of ammonia.
- a part of the ammonia injected from the ammonia injection nozzle 41 is decomposed into NH 2 , NH, and N on the center side of the flame F where there is less oxygen. Then, NOx is reduced by NH 2 , NH, and N in a region R 3 on the distal end side of the flame F.
- the control device 8 controls the operation of the adjustment mechanism 7 in such a manner that the injection flow rate of ammonia from the ammonia injection nozzle 41 is higher than the injection flow rate of pulverized coal from the pulverized coal injection nozzle 43 .
- the ammonia injected from the ammonia injection nozzle 41 can be sent to the region R 2 where there is less oxygen on the center side of the flame F to be decomposed. Therefore, the generation of NOx due to combustion of ammonia is suppressed, and the decomposition of ammonia is promoted. Therefore, NOx is effectively reduced, and NOx emission is suppressed.
- the injection flow rate of ammonia from the ammonia injection nozzle 41 is excessively higher than the injection flow rate of pulverized coal from the pulverized coal injection nozzle 43 , the shape of the flame F formed in front of the burner 4 and the phenomenon occurring in the flame F may deviate from the example of FIG. 6 .
- the ammonia injected from the ammonia injection nozzle 41 extends ahead of the region R 2 , which is the decomposition region of ammonia, in a state where the ammonia is not sufficiently decomposed. In this case, the amounts of NH 2 , NH, and N generated by decomposition of ammonia are reduced, and the effect of suppressing NOx emission can decrease.
- control device 8 preferably controls the operation of the adjustment mechanism 7 in such a manner that the injection flow rate of ammonia from the ammonia injection nozzle 41 is higher than the injection flow rate of pulverized coal from the pulverized coal injection nozzle 43 and is less than or equal to an upper limit rate.
- the upper limit rate is, for example, a rate higher by a predetermined ratio with respect to the injection flow rate of pulverized coal.
- the flame F formed by the combustion device 100 has an elongated shape. This increases the time during which the pulverized coal comes into contact with the oxygen, thereby promoting the combustion of the pulverized coal. Therefore, generation and discharge of unburned fuel are suppressed.
- FIG. 8 is a schematic diagram illustrating a combustion device 100 A according to a modification. As illustrated in FIG. 8 , the combustion device 100 A is an example in which the adjustment mechanism 7 of the combustion device 100 described above is replaced with an adjustment mechanism 7 A.
- FIG. 9 is a cross-sectional view illustrating the inside of the ammonia injection nozzle 41 A according to the modification. Specifically, FIG. 9 is a cross-sectional view taken along line X-X in FIG. 8 orthogonal to the central axis of the ammonia injection nozzle 41 A.
- a plurality of supply pipes 41 e is included in a main body 41 a of the ammonia injection nozzle 41 A.
- the number of supply pipes 41 e is six.
- the number of supply pipes 41 e may be other than six.
- a supply pipe 41 e has a tubular shape such as a cylindrical shape.
- the supply pipes 41 e extend in the axial direction of the main body 41 a .
- the supply pipes 41 e are arranged at equal intervals in the circumferential direction of the main body 41 a .
- the arrangement of the supply pipes 41 e in the main body 41 a is not limited to the example of FIG. 9 .
- Ammonia supplied from an ammonia tank 6 into the main body 41 a passes through ammonia flow paths 41 f each of which is an internal space of a supply pipe 41 e and is injected from an injection port 41 c .
- the ammonia injection nozzle 41 includes the plurality of ammonia flow paths 41 f.
- the adjustment mechanism 7 A in FIG. 8 adjusts the number of ammonia flow paths 41 f through which ammonia flows among the plurality of ammonia flow paths 41 f , thereby adjusting the injection flow rate of ammonia from the ammonia injection nozzle 41 A.
- the adjustment mechanism 7 A includes a switching valve 71 A.
- the switching valve 71 A is included in a flow path connecting the ammonia tank 6 and the ammonia injection nozzle 41 A.
- the switching valve 71 A switches each of the supply pipes 41 e between a state in which ammonia is supplied from the ammonia tank 6 and a state in which ammonia is not supplied from the ammonia tank 6 . That is, the switching valve 71 A switches supply pipes 41 e serving as the supply destination of ammonia among the plurality of supply pipes 41 e .
- the number of ammonia flow paths 41 f through which ammonia flows among the plurality of ammonia flow paths 41 f is adjusted.
- the flow rate of ammonia injected from the injection port 41 c is faster as compared to a case where ammonia flows through all the ammonia flow paths 41 f .
- the adjustment mechanism 7 A can adjust the injection flow rate of ammonia from the ammonia injection nozzle 41 A by adjusting the number of ammonia flow paths 41 f through which ammonia flows among the plurality of ammonia flow paths 41 f . As described above, the adjustment mechanism 7 A appropriately achieves adjustment of the injection flow rate of ammonia.
- the control device 8 controls the adjustment mechanism 7 A in such a manner that the injection flow rate of ammonia is higher than the injection flow rate of pulverized coal.
- the control device 8 controls the switching valve 71 A of the adjustment mechanism 7 A in such a manner that the number of ammonia flow paths 41 f through which ammonia flows varies depending on the injection flow rate of pulverized coal. This makes it possible to make the injection flow rate of ammonia to be higher than the injection flow rate of pulverized coal. Therefore, similarly to the combustion device 100 described above, the NOx emission is suppressed. In addition, generation and discharge of unburned fuel are suppressed.
- the control device 8 may change the number of ammonia flow paths 41 f through which ammonia flows depending on a parameter other than the injection flow rate of pulverized coal. For example, the control device 8 may change the number of ammonia flow paths 41 f through which ammonia flows depending on the required combustion amount in the furnace 2 , the required load of the boiler 1 , or the required power generation amount of the boiler 1 .
- the adjustment mechanism 7 and the adjustment mechanism 7 A have been described as examples of the adjustment mechanism that adjusts the injection flow rate of ammonia from the ammonia injection nozzle 41 .
- a mechanism other than the adjustment mechanism 7 or the adjustment mechanism 7 A may be used as long as the mechanism has a function of adjusting the injection flow rate of ammonia from the ammonia injection nozzle 41 .
- the adjustment mechanism 7 that adjusts the opening area of the injection port 41 c of the ammonia injection nozzle 41 and the adjustment mechanism 7 A that adjusts the number of ammonia flow paths 41 f through which ammonia flows among the plurality of ammonia flow paths 41 f may be used in combination.
- combustion devices 100 and 100 A are provided to the furnace 2 of the boiler 1 have been described above.
- the combustion devices 100 and 100 A can be used in various furnaces of equipment other than the boiler 1 .
- the present disclosure contributes to stabilization of combustion by a combustion device used in a boiler or the like and a reduction in the frequency repairs of the combustion device and thus can contribute to, for example, goal 7 of the sustainable development goals (SDGs) “Ensure access to affordable, reliable, sustainable and modern energy for all” and goal 13 “Take urgent action to combat climate change and its impacts”.
- SDGs sustainable development goals
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Abstract
A combustion device includes: an ammonia injection nozzle having an injection port facing an internal space of a furnace; a pulverized coal injection nozzle having an injection port facing the internal space of the furnace; an adjustment mechanism that adjusts an injection flow rate of ammonia from the ammonia injection nozzle; and a control device that controls an operation of the adjustment mechanism in such a manner that the injection flow rate of ammonia from the ammonia injection nozzle is higher than an injection flow rate of pulverized coal from the pulverized coal injection nozzle.
Description
- This application is a continuation application of International Application No. PCT/JP2022/024360, filed on Jun. 17, 2022, which claims priority to Japanese Patent Application No. 2021-169141, filed on Oct. 14, 2021, the entire contents of which are incorporated by reference herein.
- The present disclosure relates to a combustion device and a boiler. The present application claims the benefit of priority based on Japanese Patent Application No. 2021-169141 filed on Oct. 14, 2021, the content of which is incorporated herein.
- In a burner provided in a furnace such as a boiler, there is a burner having an ammonia injection nozzle that injects ammonia as fuel. By using ammonia as fuel, carbon dioxide emission is reduced. For example,
Patent Literature 1 discloses a burner that performs co-firing of pulverized coal and ammonia as fuel. -
- Patent Literature 1: JP 2019-086189 A
- In a burner that performs co-firing of pulverized coal and ammonia as fuel, nitrogen oxides (hereinafter, also referred to as NOx) are generated and reduced in a flame formed in front of the burner. Depending on the operating conditions, the reduction of NOx is not sufficiently performed, and the amount of NOx emission may increase.
- Therefore, a new proposal for suppressing NOx emission is desired.
- An object of the present disclosure is to provide a combustion device and a boiler capable of suppressing emission of nitrogen oxides (NOx).
- In order to solve the above problem, a combustion device according to the present disclosure includes: an ammonia injection nozzle having an injection port facing an internal space of a furnace; a pulverized coal injection nozzle having an injection port facing the internal space of the furnace; an adjustment mechanism that adjusts an injection flow rate of ammonia from the ammonia injection nozzle; and a control device that controls an operation of the adjustment mechanism in such a manner that the injection flow rate of ammonia from the ammonia injection nozzle is higher than an injection flow rate of pulverized coal from the pulverized coal injection nozzle.
- The adjustment mechanism may include a mechanism that adjusts an opening area of the injection port of the ammonia injection nozzle.
- The ammonia injection nozzle may include a plurality of ammonia flow paths, and the adjustment mechanism may include a mechanism that adjusts the number of ammonia flow paths through which ammonia flows among the plurality of ammonia flow paths.
- In order to solve the above disadvantage, the boiler of the present disclosure includes the combustion device described above.
- According to the present disclosure, it is possible to suppress emission of nitrogen oxides (NOx).
-
FIG. 1 is a schematic diagram illustrating a boiler according to the present embodiment. -
FIG. 2 is a schematic diagram illustrating a combustion device according to the present embodiment. -
FIG. 3 is a schematic diagram illustrating an adjustment mechanism according to the present embodiment. -
FIG. 4 is a schematic diagram illustrating a state in which the opening area of an injection port of an ammonia injection nozzle according to the present embodiment is smaller than that in the example ofFIG. 3 . -
FIG. 5 is a flowchart illustrating an example of a flow of processing performed by a control device according to the present embodiment. -
FIG. 6 is a diagram for explaining a flame formed by the combustion device according to the present embodiment. -
FIG. 7 is a diagram for explaining a flame formed by a combustion device according to a comparative example. -
FIG. 8 is a schematic diagram illustrating a combustion device according to a modification. -
FIG. 9 is a cross-sectional view illustrating the inside of an ammonia injection nozzle according to a modification. - Embodiments of the present disclosure will be described below by referring to the accompanying drawings. Dimensions, materials, other specific numerical values, and the like illustrated in the embodiments are merely an example for facilitating understanding, and the present disclosure is not limited thereto unless otherwise specified. Note that, in the present specification and the drawings, components having substantially the same function and structure are denoted by the same symbol, and redundant explanations are omitted. Illustration of components not directly related to the present disclosure is omitted.
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FIG. 1 is a schematic diagram illustrating aboiler 1 according to the present embodiment. As illustrated inFIG. 1 , theboiler 1 includes afurnace 2, aflue 3, andburners 4. - In the
furnace 2, fuel is burnt to generate combustion heat. Thefurnace 2 has a tubular shape such as a rectangular tubular shape extending in the vertical direction. In thefurnace 2, high-temperature combustion gas is generated by combustion of fuel. A bottom portion of thefurnace 2 includes adischarge port 2 a for discharging ash generated by combustion of fuel to the outside. - The
flue 3 is a passage for guiding combustion gas generated in thefurnace 2 to the outside as exhaust gas. Theflue 3 is connected with an upper part of thefurnace 2. Theflue 3 has ahorizontal flue 3 a and arear flue 3 b. Thehorizontal flue 3 a extends horizontally from the upper part of thefurnace 2. Therear flue 3 b extends downward from an end of thehorizontal flue 3 a. - The
boiler 1 includes a superheater (not illustrated) installed above or on thefurnace 2. In the superheater, heat is exchanged between combustion heat generated in thefurnace 2 and water. As a result of this, water vapor is generated. Theboiler 1 may also include various devices such as a repeater, a coal economizer, and an air preheater not illustrated inFIG. 1 . - The
burners 4 are provided at a lower wall portion of thefurnace 2. In thefurnace 2, a plurality ofburners 4 is provided at intervals in the circumferential direction of thefurnace 2. Although not illustrated inFIG. 1 , the plurality ofburners 4 is provided at intervals also in the vertical direction which is the extending direction of thefurnace 2. Theburners 4 inject ammonia and pulverized coal as fuel into thefurnace 2. The fuel injected from theburners 4 burns to form a flame F in thefurnace 2. Thefurnace 2 is provided with an ignition device (not illustrated) that ignites the fuel injected from theburners 4. -
FIG. 2 is a schematic diagram illustrating acombustion device 100 according to the present embodiment. As illustrated inFIG. 2 , thecombustion device 100 includes aburner 4, anair supply unit 5, anammonia tank 6, anadjustment mechanism 7, and acontrol device 8. - The
burner 4 is attached to a wall portion of thefurnace 2 outside thefurnace 2. Theburner 4 includes anammonia injection nozzle 41, anair injection nozzle 42, and a pulverizedcoal injection nozzle 43. Theammonia injection nozzle 41 is a nozzle that injects ammonia. Theair injection nozzle 42 is a nozzle that injects air for combustion. The pulverizedcoal injection nozzle 43 is a nozzle that injects pulverized coal. - The
ammonia injection nozzle 41, theair injection nozzle 42, and the pulverizedcoal injection nozzle 43 each have a cylindrical shape. Theair injection nozzle 42 is disposed coaxially with theammonia injection nozzle 41 in such a manner as to surround theammonia injection nozzle 41. The pulverizedcoal injection nozzle 43 is disposed coaxially with theair injection nozzle 42 in such a manner as to surround theair injection nozzle 42. Theammonia injection nozzle 41, theair injection nozzle 42, and the pulverizedcoal injection nozzle 43 form a triple cylindrical structure. The central axes of theammonia injection nozzle 41, theair injection nozzle 42, and the pulverizedcoal injection nozzle 43 intersect with the wall portion of thefurnace 2. Specifically, the central axes of theammonia injection nozzle 41, theair injection nozzle 42, and the pulverizedcoal injection nozzle 43 are substantially orthogonal to the wall portion of thefurnace 2. - Hereinafter, the radial direction of the
burner 4, the axial direction of theburner 4, and the circumferential direction of theburner 4 are also simply referred to as the radial direction, the axial direction, and the circumferential direction, respectively. Thefurnace 2 side (right side inFIG. 2 ) of theburner 4 is referred to as a distal end side, and the opposite side (left side inFIG. 2 ) of theburner 4 to thefurnace 2 side is referred to as a rear end side. - The
ammonia injection nozzle 41 includes amain body 41 a, a supply port 41 b, and aninjection port 41 c. Themain body 41 a has a cylindrical shape. Themain body 41 a extends along the central axis of theburner 4. The wall thickness, the inner diameter, and the outer diameter of themain body 41 a are substantially constant regardless of the axial position. However, the wall thickness, the inner diameter, and the outer diameter of themain body 41 a may vary depending on the axial position. The supply port 41 b that is an opening is included at the rear end of themain body 41 a. The supply port 41 b is connected with theammonia tank 6. Theinjection port 41 c which is an opening is included at the distal end of themain body 41 a. Theinjection port 41 c faces the internal space of thefurnace 2. That is, theinjection port 41 c faces the internal space of thefurnace 2. - Ammonia is supplied from the
ammonia tank 6 into themain body 41 a through the supply port 41 b. As indicated by an arrow A1, the ammonia supplied into themain body 41 a flows in themain body 41 a. The ammonia that has passed through the inside of themain body 41 a is injected from theinjection port 41 c towards the internal space of thefurnace 2. In this manner, theammonia injection nozzle 41 is included in such a manner as to face the internal space of thefurnace 2. - The
ammonia tank 6 stores ammonia in liquid form. The ammonia stored in theammonia tank 6 is vaporized by a vaporizer. The vaporized ammonia is supplied to theammonia injection nozzle 41. - The
air injection nozzle 42 includes amain body 42 a and aninjection port 42 b. Themain body 42 a has a cylindrical shape. Themain body 42 a is disposed coaxially with themain body 41 a of theammonia injection nozzle 41 in such a manner as to surround themain body 41 a. Themain body 42 a has a tapered shape tapered towards the distal end side. A supply port (not illustrated) is included at the rear portion of themain body 42 a. - The supply port of the
air injection nozzle 42 is connected with an air supply source (not illustrated). For example, the supply port of theair injection nozzle 42 is exposed to the atmosphere as the air supply source. Theinjection port 42 b which is an opening is included at the distal end of themain body 42 a. On a radially inner side of the distal end of themain body 42 a, the distal end of themain body 41 a of theammonia injection nozzle 41 is positioned. Theinjection port 42 b is an annular opening between the distal end of themain body 42 a and the distal end of themain body 41 a of theammonia injection nozzle 41. Theinjection port 42 b faces the internal space of thefurnace 2. That is, theinjection port 42 b faces the internal space of thefurnace 2. - The air is supplied from the air supply source into the
main body 42 a via the supply port (not illustrated). As indicated by an arrow A2, the air supplied into themain body 42 a flows in a space between an inner peripheral portion of themain body 42 a and an outer peripheral portion of themain body 41 a of theammonia injection nozzle 41. The air having passed through the inside of themain body 42 a is injected from theinjection port 42 b towards the internal space of thefurnace 2. In this manner, theair injection nozzle 42 is included in such a manner as to face the internal space of thefurnace 2. - The pulverized
coal injection nozzle 43 includes amain body 43 a and aninjection port 43 b. Themain body 43 a has a cylindrical shape. Themain body 43 a is disposed coaxially with themain body 42 a of theair injection nozzle 42 in such a manner as to surround themain body 42 a. Themain body 43 a has a tapered shape tapered towards the distal end side. A supply port (not illustrated) is provided at the rear portion of themain body 43 a. - The supply port of the pulverized
coal injection nozzle 43 is connected with a pulverized coal supply source (not illustrated). Theinjection port 43 b which is an opening is included at the distal end of themain body 43 a. The axial position of the distal end of themain body 43 a substantially coincides with the axial position of the distal end of themain body 42 a of theair injection nozzle 42. Theinjection port 43 b is an annular opening between the distal end of themain body 43 a and the distal end of themain body 42 a of theair injection nozzle 42. Theinjection port 43 b faces the internal space of thefurnace 2. That is, theinjection port 43 b faces the internal space of thefurnace 2. - The pulverized coal is supplied into the
main body 43 a from the pulverized coal supply source via the supply port (not illustrated) together with air for conveying the pulverized coal. As indicated by an arrow A3, the pulverized coal supplied into themain body 43 a flows, together with the air, in the space between an inner peripheral portion of themain body 43 a and an outer peripheral portion of themain body 42 a of theair injection nozzle 42. The pulverized coal having passed through the inside of themain body 43 a is injected from theinjection port 43 b towards the internal space of thefurnace 2. In this manner, the pulverizedcoal injection nozzle 43 is included in such a manner as to face the internal space of thefurnace 2. - The
air supply unit 5 supplies air for combustion to the flame F formed by theburner 4 from radially outside. Theair supply unit 5 is disposed in such a manner as to cover a space between the distal end of theburner 4 and thefurnace 2. Aflow path 51 through which air flows is formed in theair supply unit 5. Theflow path 51 is formed in a cylindrical shape coaxial with theburner 4. Theflow path 51 is connected with an air supply source (not illustrated). Aninjection port 52 is formed at an end of theflow path 51 on thefurnace 2 side. - As indicated by an arrow A4, air supplied from the air supply source to the
air supply unit 5 passes through theflow path 51 and is injected from theinjection port 52 towards the internal space of thefurnace 2. Theinjection port 52 faces the internal space of thefurnace 2. That is, theinjection port 52 faces the internal space of thefurnace 2. In this manner, theair supply unit 5 is included in such a manner as to face the internal space of thefurnace 2. The air injected from theinjection port 52 of theair supply unit 5 advances towards the internal space of thefurnace 2 while swirling in the circumferential direction. - The
adjustment mechanism 7 is a mechanism for adjusting the injection flow rate of ammonia from theammonia injection nozzle 41. The injection flow rate of ammonia is the flow rate of ammonia injected from theinjection port 41 c of theammonia injection nozzle 41. In the present embodiment, theadjustment mechanism 7 adjusts the injection flow rate of ammonia from theammonia injection nozzle 41 by adjusting the opening area of theinjection port 41 c of theammonia injection nozzle 41. Details of theadjustment mechanism 7 will be described with reference toFIG. 3 . -
FIG. 3 is a schematic diagram illustrating theadjustment mechanism 7 according to the present embodiment. As illustrated inFIG. 3 , avariable unit 41 d is provided at the distal end of theammonia injection nozzle 41. As thevariable unit 41 d changes its shape, the opening area of theinjection port 41 c changes. For example, thevariable unit 41 d includes a plurality of members spaced apart in the circumferential direction, and the shape thereof can be changed in such a manner that each of the members is in an inclined attitude in which a distal end is located radially inward relative to a rear end. As such avariable unit 41 d, for example, a structure similar to that of the convergent-divergent nozzles can be adopted. - The
adjustment mechanism 7 includes adrive device 71. Thedrive device 71 changes the shape of thevariable unit 41 d of theammonia injection nozzle 41. For example, thedrive device 71 is provided at the rear end of thevariable unit 41 d and includes a power source such as a motor that generates power. Then, thedrive device 71 can change the attitude of thevariable unit 41 d by rotating thevariable unit 41 d about the rear end of thevariable unit 41 d. Theadjustment mechanism 7 can adjust the opening area of theinjection port 41 c of theammonia injection nozzle 41 by changing the shape of thevariable unit 41 d of theammonia injection nozzle 41 by thedrive device 71. -
FIG. 4 is a schematic diagram illustrating a state in which the opening area of theinjection port 41 c of theammonia injection nozzle 41 according to the present embodiment is smaller than that in the example ofFIG. 3 . In the example ofFIG. 4 , as compared with the example ofFIG. 3 , the shape of thevariable unit 41 d is changed in such a manner that the radial position of the distal end of thevariable unit 41 d moves radially inward. Accordingly, the shape of thevariable unit 41 d is tapered towards the distal end side. For example, the shape of thevariable unit 41 d inFIG. 4 is a truncated cone shape. Therefore, the opening area of theinjection port 41 c of theammonia injection nozzle 41 is reduced. - As the opening area of the
injection port 41 c of theammonia injection nozzle 41 decreases, the flow rate of ammonia injected from theinjection port 41 c increases. Therefore, theadjustment mechanism 7 can adjust the injection flow rate of ammonia from theammonia injection nozzle 41 by adjusting the opening area of theinjection port 41 c of theammonia injection nozzle 41. As described above, theadjustment mechanism 7 appropriately achieves adjustment of the injection flow rate of ammonia. - The
control device 8 inFIG. 2 includes a central processing unit (CPU), a ROM in which a program and the like are stored, a RAM as a work area, and others and controls theentire combustion device 100. In particular, thecontrol device 8 controls the operation of theadjustment mechanism 7. Specifically, thecontrol device 8 can adjust the opening area of theinjection port 41 c of theammonia injection nozzle 41 by controlling thedrive device 71 of theadjustment mechanism 7 to adjust the injection flow rate of ammonia from theammonia injection nozzle 41. -
FIG. 5 is a flowchart illustrating an example of a flow of processing performed by thecontrol device 8 according to the present embodiment. The processing flow illustrated inFIG. 5 is repeatedly executed at preset time intervals, for example. As will be described later, the processing example ofFIG. 5 is merely an example, and the processing performed by thecontrol device 8 is not limited to this example. - When the processing flow illustrated in
FIG. 5 starts, in step S101, thecontrol device 8 acquires the injection flow rate of pulverized coal from the pulverizedcoal injection nozzle 43. The injection flow rate of pulverized coal is the flow rate of the pulverized coal injected from theinjection port 43 b of the pulverizedcoal injection nozzle 43. - The supply amount of air for conveyance supplied to the pulverized
coal injection nozzle 43 varies depending on the required combustion amount in thefurnace 2. Accordingly, the injection flow rate of the pulverized coal varies depending on the required combustion amount in thefurnace 2. For example, the injection flow rate of pulverized coal increases as the required combustion amount in thefurnace 2 increases. The required combustion amount in thefurnace 2 correlates with a required load or a required power generation amount of theboiler 1. - The
control device 8 acquires the supply amount of air for conveyance, for example, a device that controls the supply amount of the air for conveyance supplied to the pulverizedcoal injection nozzle 43. Then, thecontrol device 8 can acquire the injection flow rate of the pulverized coal on the basis of the supply amount of the air for conveyance. Thecontrol device 8 may control the supply amount of air for control device supplied to the pulverizedcoal injection nozzle 43. - After step S101, in step S102, the
control device 8 controls theadjustment mechanism 7 in such a manner that the injection flow rate of ammonia is higher than the injection flow rate of pulverized coal. For example, thecontrol device 8 controls thedrive device 71 of theadjustment mechanism 7 in such a manner that the opening area of theinjection port 41 c of theammonia injection nozzle 41 varies depending on the injection flow rate of pulverized coal. This makes it possible to make the injection flow rate of ammonia to be higher than the injection flow rate of pulverized coal. - It is preferable that the
control device 8 controls theadjustment mechanism 7 in consideration of a parameter other than the opening area of theinjection port 41 c among parameters that affect the injection flow rate of ammonia. For example, the supply amount of ammonia to theammonia injection nozzle 41 can vary depending on the required combustion amount in thefurnace 2. Therefore, thecontrol device 8 preferably controls theadjustment mechanism 7 on the basis of the supply amount of ammonia to theammonia injection nozzle 41 in addition to the injection flow rate of pulverized coal. As a result, it is more appropriately achieved that the injection flow rate of ammonia is made higher than the injection flow rate of pulverized coal. - In the above description, the example has been described in which the opening area of the
injection port 41 c of theammonia injection nozzle 41 is varied depending on the injection flow rate of pulverized coal. However, thecontrol device 8 may cause the opening area of theinjection port 41 c of theammonia injection nozzle 41 to vary depending on a parameter other than the injection flow rate of pulverized coal. For example, thecontrol device 8 cause the opening area of theinjection port 41 c of theammonia injection nozzle 41 to vary depending on the required combustion amount in thefurnace 2, the required load of theboiler 1, or the required power generation amount of theboiler 1. - As described above, in the
combustion device 100 according to the present embodiment, thecontrol device 8 controls the operation of theadjustment mechanism 7 in such a manner that the injection flow rate of ammonia from theammonia injection nozzle 41 is higher than the injection flow rate of pulverized coal from the pulverizedcoal injection nozzle 43. Depending on the magnitude relationship between the injection flow rate of ammonia and the injection flow rate of pulverized coal, the shape of the flame F formed in front of theburner 4 and the phenomenon occurring in the flame F vary. Hereinafter, the shape of the flame F and a phenomenon occurring in the flame F will be described with reference toFIGS. 6 and 7 . -
FIG. 6 is a diagram for explaining the flame F formed by thecombustion device 100 according to the present embodiment. That is, the flame F illustrated inFIG. 6 is a flame of the case where the injection flow rate of ammonia is faster than the injection flow rate of pulverized coal. - In the example of
FIG. 6 , the flame F has an elongated shape extending along the central axis of theburner 4. In the vicinity of a surface layer of the flame F, as indicated by broken line arrows A5, a flow of air injected from theair supply unit 5 is formed. The pulverized coal injected from the pulverizedcoal injection nozzle 43 is pulled by the flow of air injected from theair supply unit 5 and flows in the vicinity of the surface layer of the flame F. Therefore, the pulverized coal injected from the pulverizedcoal injection nozzle 43 flows in the vicinity of the surface layer of the flame F along the flow of air indicated by the broken line arrows A5 as indicated by broken-line arrows A6. As a result, the pulverized coal burns and NOx is generated in a region R1 in the vicinity of the surface layer of the flame F. The region R1 is a combustion region of the pulverized coal. - In the example of
FIG. 6 , the injection flow rate of ammonia is faster than the injection flow rate of pulverized coal. Therefore, since the ammonia injected from theammonia injection nozzle 41 is less likely to be pulled by the flow of the air injected from theair supply unit 5, the ammonia flows through the center of the flame F in the axial direction of theburner 4 as indicated by solid arrows A7. The direction of a flow of ammonia can actually be various directions; however, the main direction is the axial direction of theburner 4. As a result, ammonia (NH3) is decomposed into NH2, NH, and N in a region R2, where there is less oxygen, on the center side of the flame F. The region R2 is located radially inward with respect to the region R1. The region R2 is a decomposition region of ammonia. The region R2 has an elongated shape extending along the central axis of theburner 4. - Then, NOx is reduced by NH2, NH, and N in a region R3 on the distal end side of the flame F. The region R3 is positioned on the front side with respect to the region R2. The region R3 is a reduction region of NOx.
-
FIG. 7 is a diagram for explaining a flame F formed by a combustion device according to a comparative example. In the comparative example, unlike the present embodiment, the injection flow rate of ammonia is lower than the injection flow rate of pulverized coal. That is, the flame F illustrated inFIG. 7 is a flame of a case where the injection flow rate of ammonia is lower than the injection flow rate of pulverized coal. - In the example of
FIG. 7 , the flame F has a shape expanded in the radial direction as compared with the example ofFIG. 6 . Similarly to the example ofFIG. 6 , as indicated by broken line arrows A5 and A6, air injected from anair supply unit 5 and pulverized coal injected from a pulverizedcoal injection nozzle 43 flow in the vicinity of a surface layer of the flame F. In the region R1 in the vicinity of the surface layer of the flame F, the pulverized coal burns, and NOx is generated. - In the example of
FIG. 7 , the injection flow rate of ammonia is lower than the injection flow rate of pulverized coal. Therefore, the ammonia injected from anammonia injection nozzle 41 is easily pulled by a flow of the air injected from theair supply unit 5. Therefore, most of the ammonia injected from theammonia injection nozzle 41 flows along the flow of the air indicated by the broken line arrows A5 as indicated by solid line arrows A7. As a result, ammonia burns, and NOx is generated in a region R4, where there is a large amount of oxygen, away from the center of the flame F towards the surface layer side. The region R4 is a combustion region of ammonia. - A part of the ammonia injected from the
ammonia injection nozzle 41 is decomposed into NH2, NH, and N on the center side of the flame F where there is less oxygen. Then, NOx is reduced by NH2, NH, and N in a region R3 on the distal end side of the flame F. - In the comparative example illustrated in
FIG. 7 , unlike the example ofFIG. 6 , most of the ammonia injected from theammonia injection nozzle 41 burns to generate NOx. Therefore, in addition to NOx generated by combustion of pulverized coal, NOx is also generated by combustion of ammonia. Therefore, the amount of NOx generated increases. In addition, most of the ammonia injected from theammonia injection nozzle 41 burns and thus is not decomposed. Therefore, the amount of NH2, NH, and N generated by decomposition of ammonia is reduced. Therefore, reduction of NOx is not sufficiently performed, and the amount of NOx emission increases. - As described above, in the present embodiment, the
control device 8 controls the operation of theadjustment mechanism 7 in such a manner that the injection flow rate of ammonia from theammonia injection nozzle 41 is higher than the injection flow rate of pulverized coal from the pulverizedcoal injection nozzle 43. As a result, as in the example ofFIG. 6 , the ammonia injected from theammonia injection nozzle 41 can be sent to the region R2 where there is less oxygen on the center side of the flame F to be decomposed. Therefore, the generation of NOx due to combustion of ammonia is suppressed, and the decomposition of ammonia is promoted. Therefore, NOx is effectively reduced, and NOx emission is suppressed. - If the injection flow rate of ammonia from the
ammonia injection nozzle 41 is excessively higher than the injection flow rate of pulverized coal from the pulverizedcoal injection nozzle 43, the shape of the flame F formed in front of theburner 4 and the phenomenon occurring in the flame F may deviate from the example ofFIG. 6 . For example, it is conceivable that the ammonia injected from theammonia injection nozzle 41 extends ahead of the region R2, which is the decomposition region of ammonia, in a state where the ammonia is not sufficiently decomposed. In this case, the amounts of NH2, NH, and N generated by decomposition of ammonia are reduced, and the effect of suppressing NOx emission can decrease. Therefore, thecontrol device 8 preferably controls the operation of theadjustment mechanism 7 in such a manner that the injection flow rate of ammonia from theammonia injection nozzle 41 is higher than the injection flow rate of pulverized coal from the pulverizedcoal injection nozzle 43 and is less than or equal to an upper limit rate. The upper limit rate is, for example, a rate higher by a predetermined ratio with respect to the injection flow rate of pulverized coal. - Furthermore, in the present embodiment, as in the example of
FIG. 6 , the flame F formed by thecombustion device 100 has an elongated shape. This increases the time during which the pulverized coal comes into contact with the oxygen, thereby promoting the combustion of the pulverized coal. Therefore, generation and discharge of unburned fuel are suppressed. -
FIG. 8 is a schematic diagram illustrating acombustion device 100A according to a modification. As illustrated inFIG. 8 , thecombustion device 100A is an example in which theadjustment mechanism 7 of thecombustion device 100 described above is replaced with anadjustment mechanism 7A. - An
ammonia injection nozzle 41A of thecombustion device 100A has a different internal structure as compared with theammonia injection nozzle 41 of thecombustion device 100 described above.FIG. 9 is a cross-sectional view illustrating the inside of theammonia injection nozzle 41A according to the modification. Specifically,FIG. 9 is a cross-sectional view taken along line X-X inFIG. 8 orthogonal to the central axis of theammonia injection nozzle 41A. - As illustrated in
FIG. 9 , a plurality ofsupply pipes 41 e is included in amain body 41 a of theammonia injection nozzle 41A. In the example ofFIG. 9 , the number ofsupply pipes 41 e is six. However, the number ofsupply pipes 41 e may be other than six. Asupply pipe 41 e has a tubular shape such as a cylindrical shape. Thesupply pipes 41 e extend in the axial direction of themain body 41 a. In the example ofFIG. 9 , thesupply pipes 41 e are arranged at equal intervals in the circumferential direction of themain body 41 a. However, the arrangement of thesupply pipes 41 e in themain body 41 a is not limited to the example ofFIG. 9 . Ammonia supplied from anammonia tank 6 into themain body 41 a passes throughammonia flow paths 41 f each of which is an internal space of asupply pipe 41 e and is injected from aninjection port 41 c. As described above, theammonia injection nozzle 41 includes the plurality ofammonia flow paths 41 f. - The
adjustment mechanism 7A inFIG. 8 adjusts the number ofammonia flow paths 41 f through which ammonia flows among the plurality ofammonia flow paths 41 f, thereby adjusting the injection flow rate of ammonia from theammonia injection nozzle 41A. - Specifically, the
adjustment mechanism 7A includes a switchingvalve 71A. The switchingvalve 71A is included in a flow path connecting theammonia tank 6 and theammonia injection nozzle 41A. The switchingvalve 71A switches each of thesupply pipes 41 e between a state in which ammonia is supplied from theammonia tank 6 and a state in which ammonia is not supplied from theammonia tank 6. That is, the switchingvalve 71A switchessupply pipes 41 e serving as the supply destination of ammonia among the plurality ofsupply pipes 41 e. As a result, the number ofammonia flow paths 41 f through which ammonia flows among the plurality ofammonia flow paths 41 f is adjusted. - Among the plurality of
ammonia flow paths 41 f, the smaller the number ofammonia flow paths 41 f through which ammonia flows, the smaller the total value of the flow path cross-sectional areas in theammonia injection nozzle 41, which increases the flow rate of ammonia injected from theinjection port 41 c. For example, in a case where ammonia flows through only someammonia flow paths 41 f among the plurality ofammonia flow paths 41 f, the flow rate of ammonia injected from theinjection port 41 c is faster as compared to a case where ammonia flows through all theammonia flow paths 41 f. Therefore, theadjustment mechanism 7A can adjust the injection flow rate of ammonia from theammonia injection nozzle 41A by adjusting the number ofammonia flow paths 41 f through which ammonia flows among the plurality ofammonia flow paths 41 f. As described above, theadjustment mechanism 7A appropriately achieves adjustment of the injection flow rate of ammonia. - Also in the
combustion device 100A, similarly to thecombustion device 100 described above, thecontrol device 8 controls theadjustment mechanism 7A in such a manner that the injection flow rate of ammonia is higher than the injection flow rate of pulverized coal. For example, thecontrol device 8 controls the switchingvalve 71A of theadjustment mechanism 7A in such a manner that the number ofammonia flow paths 41 f through which ammonia flows varies depending on the injection flow rate of pulverized coal. This makes it possible to make the injection flow rate of ammonia to be higher than the injection flow rate of pulverized coal. Therefore, similarly to thecombustion device 100 described above, the NOx emission is suppressed. In addition, generation and discharge of unburned fuel are suppressed. - The
control device 8 may change the number ofammonia flow paths 41 f through which ammonia flows depending on a parameter other than the injection flow rate of pulverized coal. For example, thecontrol device 8 may change the number ofammonia flow paths 41 f through which ammonia flows depending on the required combustion amount in thefurnace 2, the required load of theboiler 1, or the required power generation amount of theboiler 1. - Although the embodiments of the present disclosure have been described with reference to the accompanying drawings, it is naturally understood that the present disclosure is not limited to the above embodiments. It is clear that those skilled in the art can conceive various modifications or variations within the scope described in the claims, and it is understood that they are naturally also within the technical scope of the present disclosure.
- In the above description, the
adjustment mechanism 7 and theadjustment mechanism 7A have been described as examples of the adjustment mechanism that adjusts the injection flow rate of ammonia from theammonia injection nozzle 41. However, a mechanism other than theadjustment mechanism 7 or theadjustment mechanism 7A may be used as long as the mechanism has a function of adjusting the injection flow rate of ammonia from theammonia injection nozzle 41. Furthermore, theadjustment mechanism 7 that adjusts the opening area of theinjection port 41 c of theammonia injection nozzle 41 and theadjustment mechanism 7A that adjusts the number ofammonia flow paths 41 f through which ammonia flows among the plurality ofammonia flow paths 41 f may be used in combination. - The examples in which the
combustion devices furnace 2 of theboiler 1 have been described above. However, the furnace in which thecombustion device combustion devices boiler 1. - The present disclosure contributes to stabilization of combustion by a combustion device used in a boiler or the like and a reduction in the frequency repairs of the combustion device and thus can contribute to, for example,
goal 7 of the sustainable development goals (SDGs) “Ensure access to affordable, reliable, sustainable and modern energy for all” and goal 13 “Take urgent action to combat climate change and its impacts”.
Claims (8)
1. A combustion device comprising:
an ammonia injection nozzle having an injection port facing an internal space of a furnace;
a pulverized coal injection nozzle having an injection port facing the internal space of the furnace;
an adjustment mechanism that adjusts an injection flow rate of ammonia from the ammonia injection nozzle; and
a control device that controls an operation of the adjustment mechanism in such a manner that the injection flow rate of ammonia from the ammonia injection nozzle is higher than an injection flow rate of pulverized coal from the pulverized coal injection nozzle.
2. The combustion device according to claim 1 ,
wherein the adjustment mechanism includes a mechanism that adjusts an opening area of the injection port of the ammonia injection nozzle.
3. The combustion device according to claim 1 ,
wherein the ammonia injection nozzle comprises a plurality of ammonia flow paths, and
the adjustment mechanism includes a mechanism that adjusts a number of ammonia flow paths through which ammonia flows among the plurality of ammonia flow paths.
4. The combustion device according to claim 2 ,
wherein the ammonia injection nozzle comprises a plurality of ammonia flow paths, and
the adjustment mechanism includes a mechanism that adjusts a number of ammonia flow paths through which ammonia flows among the plurality of ammonia flow paths.
5. A boiler comprising the combustion device according to claim 1 .
6. A boiler comprising the combustion device according to claim 2 .
7. A boiler comprising the combustion device according to claim 3 .
8. A boiler comprising the combustion device according to claim 4 .
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP2021-169141 | 2021-10-14 | ||
JP2021169141 | 2021-10-14 | ||
PCT/JP2022/024360 WO2023062876A1 (en) | 2021-10-14 | 2022-06-17 | Combustion device and boiler |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2022/024360 Continuation WO2023062876A1 (en) | 2021-10-14 | 2022-06-17 | Combustion device and boiler |
Publications (2)
Publication Number | Publication Date |
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US20240133550A1 true US20240133550A1 (en) | 2024-04-25 |
US20240230085A9 US20240230085A9 (en) | 2024-07-11 |
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AU2022367978B2 (en) | 2024-05-09 |
AU2022367978A1 (en) | 2024-01-18 |
JPWO2023062876A1 (en) | 2023-04-20 |
CN117795250A (en) | 2024-03-29 |
WO2023062876A1 (en) | 2023-04-20 |
KR20240017097A (en) | 2024-02-06 |
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