Combustion equipment with additional air supply device

Abstract

To provide a combustion facility comprising an additional air supply device capable of changing an in-bed air ratio while keeping an in-bed superficial velocity within a certain range even if the kind of a combustion body is changed.SOLUTION: A combustion facility 1 combusts a combustion body in a fluidized bed 22 formed in an interior, and comprises a fluidized bed furnace 2 in which a flowing air supply part for injecting flowing air into the fluidized bed 22 is provided in a lower part, and a combustion body charging part 29 for supplying the combustion body to the fluidized bed 22 is provided in an upper part. The fluidized bed furnace 2 comprises an additional air supply device 9 for supply additional air 100 for in-bed air ratio adjustment to the fluidized bed 22.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a combustion facility including a fluidized bed furnace and an additional air supply device.

Background Art

[0002] Conventionally, a fluidized bed furnace is known which forms a fluidized bed inside and burns combustibles such as waste (e.g., garbage and sludge) and fuel (e.g., biomass fuel and waste plastic fuel) in the fluidized bed. In such a fluidized bed furnace, in order to fluidize the fluid medium (BM: Bed Material, generally silica sand) constituting the fluidized bed, fluidizing air is ejected from below into the fluidized bed, and the combustible to be burned in the fluidized bed is supplied from above the fluidized bed and burned in the fluidized bed.

[0003] On the other hand, in recent years, as a combustible to be burned in the fluidized bed, due to the trend of decarbonization of energy supply, the demand for biomass fuel has been increasing. Also, due to the export prohibition measures for waste plastics due to marine pollution, the demand for using waste plastics as fuel has been increasing. Furthermore, the treatment of waste tires and the like has also become an issue, and their use as fuel is being considered.

[0004] However, since these combustibles are scattered throughout Japan and the reserves are small, it is difficult to secure a large quantity of a single type for a long period. Against this background, fluidized bed furnaces using biomass fuel and waste-based solid fuel as combustibles are required to be compatible with a variety of fuel types.

[0005] As a prior art using waste plastic-based fuel as a combustible, for example, there is one in which a supply pipe for low specific gravity solid waste is inserted into the inside of the fluidized bed, and the low specific gravity solid waste is directly supplied to the furnace bottom side of the fluidized bed and burned (see, for example, Patent Document 1).

[0006] Furthermore, other prior art involves separating high-calorie waste from the waste to be burned in the incinerator, feeding the high-calorie waste into the empty tower section from above, and feeding the remaining waste into the empty tower section from below (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-42424 [Patent Document 2] Japanese Patent Application Publication No. 8-303737 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, while the in-bed air ratio of a fluidized bed furnace is designed according to the combustion element, the furnace is also designed so that a predetermined empty bed velocity is achieved with respect to the amount of fluidizing air at the above in-bed air ratio in order to stabilize the flow of the fluidized medium. When the type of combustion element is changed, one possible method to stably burn the combustion element is to change the in-bed air ratio by changing the amount of fluidizing air that flows the fluidized medium in the fluidized bed furnace. However, increasing the amount of fluidizing air makes it impossible to keep the empty bed velocity in the fluidized bed furnace within a certain range, making it difficult to stably flow the fluidized medium, and the change in the flow velocity of the fluidized medium accelerates wear inside the furnace.

[0009] Furthermore, neither Patent Document 1 nor Patent Document 2 mentions any issues regarding the intra-bed air ratio in a fluidized bed furnace when the type of combustion element is changed.

[0010] Therefore, the present invention aims to provide a combustion system equipped with an additional air supply device that can change the air-to-stack ratio while keeping the empty-to-stack velocity within the strata within a certain range, even when the type of combustion element is changed. [Means for solving the problem]

[0011] To achieve the above objective, the combustion equipment equipped with an additional air supply device according to the present invention is a combustion equipment for burning a combustible body in a fluidized bed formed inside, comprising a fluidized bed furnace having a fluidized air supply unit at the bottom for injecting fluidized air into the fluidized bed and a combustible body input unit at the top for supplying the combustible body to the fluidized bed, and the fluidized bed furnace is equipped with an additional air supply device for supplying additional air to the fluidized bed for adjusting the intra-bed air ratio. In this specification and the claims, "intra-bed air ratio" means "air ratio contributing to intra-bed combustion".

[0012] This configuration allows additional air to be blown into the fluidized bed where the combustion material is burned and used as combustion air. This makes it possible to change the air-fuel ratio within the bed while keeping the empty bed velocity within the bed within a certain range, even when changing the type of combustion material. Therefore, a variety of combustion materials can be burned stably without changing the structure of the fluidized bed furnace. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a combustion system equipped with an additional air supply device that can change the air ratio within the layer while keeping the empty column velocity within the layer within a certain range, even when the type of combustion element is changed. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a schematic diagram showing a combustion equipment according to one embodiment of the present invention. [Figure 2] Figure 2 is a cross-sectional view showing the additional air supply section of the combustion equipment shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram showing a modified example of a fluidized bed furnace according to the present invention. [Modes for carrying out the invention]

[0015] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The combustion equipment 1 according to the following embodiment is only one embodiment. Therefore, the present invention is not limited to the following embodiment, and additions, deletions, and modifications are possible without departing from the spirit of the invention.

[0016] (Configuration of the combustion equipment) Figure 1 is a schematic diagram showing a combustion equipment 1 according to one embodiment. Figure 2 is a cross-sectional view showing an additional air supply unit 92 of the combustion equipment 1 shown in Figure 1. As shown in Figure 1, the combustion equipment 1 includes a fluidized bed furnace 2 for burning a combustible material and a boiler 5 for recovering heat from exhaust gas discharged from the fluidized bed furnace 2. Furthermore, the combustion equipment 1 includes a dust collector 62 connected to the boiler 5 by a first gas duct 61 and a chimney 65 connected to the dust collector 62 by a second gas duct 63. The dust collector 62 is, for example, a bag filter. An induced draft fan 64 is provided in the second gas duct 63. However, the combustion equipment 1 does not necessarily have to include the boiler 5, and the fluidized bed furnace 2 may be connected to the dust collector 62 by the first gas duct 61.

[0017] The fluidized bed furnace 2 of this embodiment has an internal circulation system in which a fluidized bed section 20 is formed inside. The fluidized bed furnace 2 of this embodiment also has a dispersion plate system. Above the fluidized bed section 20, a free board section 21 for secondary combustion is formed. The fluidized bed section 20 has a fluidized bed 22 formed of a fluidizing medium 10 such as silica sand. The fluidized bed 22 of this embodiment is partitioned by a first partition wall 23 and a second partition wall 24 into a combustion cell 25 in the central part, circulation cells 26 formed on both sides of the combustion cell, and heat recovery cells 27 formed on both sides of the circulation cells. That is, the combustion cell 25 and the heat recovery cells 27 are provided adjacent to each other with the circulation cell 26 in between. The upper end of the first partition wall 23 is located above the fluidized bed 22, and partitions the combustion cell 25 and the circulation cell 26 while keeping them in communication below. The second partition wall 24 has its upper end located on the upper surface of the fluidized bed 22 and its lower end located below the first partition wall 23, and partitions the circulation cell 26 and the heat recovery cell 27 in a manner that allows them to communicate above and below. The heat recovery cell 27 is equipped with a heat exchanger 28 for generating and / or superheating steam.

[0018] Further, a freeboard portion 21 formed upward from the fluidized bed portion 20 is provided with a combustion body input portion 29 for supplying a combustion body such as solid fuel to the fluidized bed 22. The combustion body input portion 29 is provided at an angle such that the combustion body introduced into the interior of the fluidized bed furnace 2 from the combustion body input port 29a is introduced into the combustion cells 25 of the fluidized bed 22.

[0019] A fluidizing air supply device 3 is provided at the lower part of the fluidized bed furnace 2. The fluidizing air supply device 3 includes a plurality of air supply holes 30 serving as a fluidizing air supply portion for ejecting fluidizing air into the fluidized bed 22, a combustion cell air supply device 31, a circulation cell air supply device 32, and a heat recovery cell air supply device 33. The fluidizing air supply device 3 further includes a first fan 34 for supplying air to each of the combustion cell air supply device 31, the circulation cell air supply device 32, and the heat recovery cell air supply device 33. The combustion cell air supply device 31 includes a flow rate adjustment device 31a for adjusting the flow rate of air. Similarly, the circulation cell air supply device 32 includes a flow rate adjustment device 32a, and the heat recovery cell air supply device 33 includes a flow rate adjustment device 33a. By each of the combustion cell air supply device 31, the circulation cell air supply device 32, and the heat recovery cell air supply device 33, the combustion cell air 35, the circulation cell air 36, and the heat recovery cell air 37 are respectively adjusted to appropriate flow rates. The combustion cell air 35 is ejected into the combustion cell 25, the circulation cell air 36 is ejected into the circulation cell 26, and the heat recovery cell air 37 is ejected into the heat recovery cell 27.

[0020] In this fluidizing air supply device 3, the speed of the combustion cell air 35 is greater than the speeds of the circulation cell air 36 and the heat recovery cell air 37. As a result, the superficial velocity of the combustion cell 25 of the fluidized bed 22 becomes greater than the superficial velocities of the circulation cell 26 and the heat recovery cell 27, and a density difference occurs in the fluidizing medium 10. Due to this density difference, the fluidizing medium 10 is caused to flow. Specifically, this fluidizing medium 10 is caused to flow from the combustion cell 25 through the circulation cell 26 to the heat recovery cell 27, and further from the heat recovery cell 27 to the combustion cell 25.

[0021] More specifically, the fluid medium 10 that has become hot after burning the combustible in the combustion cell 25 of the fluidized bed 22 flows from the combustion cell 25 through the lower part of the first partition wall 23 into the circulation cell 26, and the fluid medium 10 in the circulation cell 26 flows through the upper part of the second partition wall 24 into the heat recovery cell 27. Since the heat exchanger 28 is arranged in the heat recovery cell 27, the heat of the fluid medium 10 flowing into the heat recovery cell 27 is recovered by the heat exchanger 28. On the other hand, the fluid medium 10 from which heat has been recovered in the heat recovery cell 27 flows from the heat recovery cell 27 through the lower parts of the second partition wall 24 and the first partition wall 23 into the combustion cell 25.

[0022] In this way, the fluidized bed 22 is partitioned by the first partition wall 23 and the second partition wall 24 into a combustion cell 25, a circulation cell 26, and a heat recovery cell 27, and circulates the fluid medium 10 that has become hot in the combustion cell 25 as described above to recover heat in the heat recovery cell 27.

[0023] Further, the freeboard part 21 is provided with a tertiary air supply part 39 for supplying tertiary air for secondary combustion. The tertiary air supply part 39 is provided above the combustible input port 29a of the combustible input part 29. Tertiary air 42 is supplied to the tertiary air supply part 39 from a second fan 41 through a third supply path 40. In this figure, a plurality of second fans 41 are shown for clarity of the configuration, but it is not limited to this example.

[0024] Also, the bottom of the fluidized bed part 20 is a hopper 45 that discharges residues of the combustible (such as ash and metal pieces) together with the fluid medium 10. The hopper 45 has a discharge port 46 at the center, and the inner surface of the hopper 45 is inclined obliquely downward toward the discharge port 46. The air supply hole 30 is provided in the hopper 45.

[0025] However, the configuration of the fluidized bed furnace 2 is not limited to this and can be changed as appropriate. For example, the combustible may be burned throughout the inside of the fluidized bed furnace 2.

[0026] In the boiler 5 described above, steam is generated by the exhaust gas discharged from the fluidized bed furnace 2. More specifically, the boiler 5 has a first flue 50 that connects the upper parts of the freeboard section 21 located above the fluidized bed furnace 2 and a second flue 51 that connects the lower parts of the first flue 50 and the first flue 51. Heat exchangers 52 and 53 are arranged in the second flue 51. Heat exchangers may also be arranged in the first flue 50. The steam generated in the boiler 5 is sent to a turbine (not shown) and used for power generation or as a heat source.

[0027] Furthermore, the combustion equipment 1 is equipped with an additional air supply device 9 that supplies additional air for adjusting the in-bed air ratio of the fluidized bed 22. In this embodiment, the additional air supply device 9 includes an additional air supply passage 90, an additional air supply fan 91, and an additional air supply unit 92. The additional air supply port 93 of the additional air supply unit 92 is located below the combustion body inlet 29a of the combustion body inlet 29 and above the upper surface of the fluidized bed 22 of the fluidized bed 20.

[0028] As shown in Figure 2, the additional air supply unit 92 in this embodiment is provided on the wall surface of the fluidized bed furnace 2. The additional air supply unit 92 is positioned diagonally downward at a predetermined angle θ with respect to the wall surface of the fluidized bed furnace 2. The angle θ can be set to the angle at which the additional air 100 is injected from the additional air supply port 93 of the additional air supply unit 92 toward the area directly above the combustion cell 25 of the fluidized bed 22.

[0029] With the combustion equipment 1 configured as described above, additional air can be supplied from the additional air supply fan 91 to the additional air supply passage 90, and additional air can be supplied to the fluidized bed 22 from the additional air supply port 93 of the additional air supply unit 92. The additional air is used as combustion air in the fluidized bed 22. The additional air is injected towards the area directly above the combustion cell 25 of the fluidized bed 22. The velocity of the additional air can be made greater than the empty bed velocity at the combustion cell 25. By making the injection velocity of the additional air greater than the empty bed velocity, the additional air can be appropriately supplied to the combustion cell 25 of the fluidized bed 22. The supply amount and flow velocity of the additional air can be adjusted with the additional air supply fan 91. Note that the supply amount of additional air may also be adjusted by installing a flow rate control device such as a damper on the additional air supply device 9 or the additional air supply fan 91. Thus, with the combustion equipment 1, even if the type of combustion element is changed, the in-bed air ratio can be changed by supplying additional air from the additional air supply unit and using it as combustion air. Therefore, with the combustion equipment 1, even if the type of fuel element is changed, the empty bed velocity in the bed can be kept within a certain range. For this reason, when the combustion equipment 1 includes a fluidized bed furnace 2 and a boiler 5, the initially planned boiler evaporation rate can be secured even if the type of fuel element is changed.

[0030] (modified version) Figure 3 is a schematic diagram showing a modified configuration of the fluidized bed furnace 2. Figure 3 shows only the fluidized bed 22 portion in the above-described embodiment, and only configurations that differ from the above-described embodiment will be explained, while identical configurations will be denoted by the same reference numerals and their explanations will be omitted. In the modified configuration shown in Figure 3, the fluidized air supply unit that supplies fluidized air to the fluidized bed 22 uses a diffuser pipe system in which fluidized air is ejected from a diffuser pipe 38 provided inside the fluidized bed 22. Since known technology can be used for the configuration of supplying air to the diffuser pipe 38, an explanation will be omitted. Also in Figure 3, the fluidized bed 22 consists of a combustion cell 25 in the central part and heat recovery cells 27 formed on both sides of it. The combustion cell 25 and the heat recovery cells 27 are separated by a first partition wall 23. In the combustion equipment 1, the fluidized air supply unit that supplies fluidized air to the fluidized bed 22 may be either a dispersion plate system or a diffuser pipe system. Also, the fluidized bed 22 may have a configuration with or without a circulation cell 26.

[0031] In the above embodiment, the additional air supply unit 92 is shown in one location, but the additional air supply unit 92 may be provided in multiple locations. For example, it can be provided at positions opposite the fluidized bed unit 20.

[0032] Furthermore, in the above embodiment, the combustion cell 25 is provided with circulation cells 26 and heat recovery cells 27 on both sides, but the configuration can also be applied to one side only, where the circulation cells 26 and heat recovery cells 27 are provided. If there is no circulation cell 26, the configuration can also be applied to one side only, where the heat recovery cells 27 are provided.

[0033] Furthermore, although the above embodiment describes an example of a fluidized bed furnace 2 with an internal circulation system, it can also be applied to other types of fluidized bed furnaces such as those with an external circulation system and a bubbling system.

[0034] Furthermore, the configurations and combinations thereof in the embodiments described above are merely examples, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of the present invention. The present invention is not limited by the embodiments, but is limited only by the scope of the claims.

[0035] (summary) The combustion equipment 1 according to the present invention is a combustion equipment 1 that burns a combustion body in a fluidized bed 22 formed inside, and comprises a fluidized bed furnace 2 provided at the bottom of which a fluidized air supply unit is provided for injecting fluidized air into the fluidized bed 22, and a combustion body input unit 29 provided at the top of which a combustion body input unit 29 is provided for supplying the combustion body to the fluidized bed 22, and the fluidized bed furnace 2 comprises an additional air supply device 9 that supplies additional air 100 for adjusting the in-bed air ratio to the fluidized bed 22.

[0036] This configuration allows additional air 100 to be injected into the fluidized bed 22 where the combustion material is burned. This makes it possible to change the air-to-bed ratio while keeping the empty bed velocity within the bed within a certain range, even when the type of combustion material is changed. Therefore, various combustion materials can be burned stably without changing the structure of the fluidized bed furnace 2. If the combustion equipment 1 includes a boiler, the initially planned boiler evaporation rate can be maintained even when the type of fuel material is changed.

[0037] Furthermore, the fluidized bed furnace 2 may have a fluidized bed section 20 including the fluidized bed 22 and a free board section 21 for secondary combustion formed above the fluidized bed section 20, and the additional air supply device 9 may include an additional air supply section 92 having an additional air supply port between the secondary combustion air supply section of the free board section 21 and the upper surface of the fluidized bed 22. With this configuration, additional air 100 can be appropriately supplied to the fluidized bed from the additional air supply section 92 located close to the fluidized bed.

[0038] Furthermore, the fluidized bed 22 may have a heat-recovering cell and a combustion cell, and the additional air supply unit may be positioned at an angle to blow additional air directly above the combustion cell 25. With this configuration, additional air 100 can be appropriately supplied to the combustion cell of the fluidized bed 22.

[0039] Furthermore, the additional air supply device 9 may be configured to supply the additional air at a speed greater than the empty velocity of the combustion cell 25. With this configuration, the additional air 100 can be properly delivered to the fluidized bed 22 and used as combustion air. [Explanation of symbols]

[0040] 1. Combustion equipment 2 Fluidized bed furnace 3. Fluidized air supply device 5 Boiler 9. Additional air supply device 10 Fluid medium 20. Fluidized bed section 21 Freeboard Section 22 Fluidized bed 23. First partition wall 24. Second partition wall 25 Combustion Cells 26 Circulating Cells 27 Heat-recovering cells 28 Heat exchanger 29 Combustion element input section 29a Combustion element inlet 30 Air supply port (fluidized air supply section) 31 Combustion cell air supply device 31a Flow control device 32 Circulating cell air supply device 32a Flow control device 33 Heat Recovery Cell Air Supply System 33a Flow control device 34 First Fan 35 Combustion cell air 36 Circulating cell air 37 Heat-absorbing cell air 38 Air diffuser 39. Tertiary air supply unit (secondary combustion air supply unit) 40 Third supply route 41 Second Fan 42 Third air 45 Hopper 46 Outlet 50 1st flue 51 Second flue 52 Heat exchanger 53 Heat exchanger 61. First Gas Duct 62 Dust collector 63 Second Gas Duct 64 Inducing Fan 65 Chimney 90 Additional air supply channels 91 Additional air supply fan 92 Additional air supply unit 93 Additional air supply port 100 additional air

Claims

1. A combustion apparatus that burns a combustible material in a fluidized bed formed inside, The fluidized bed is divided into a combustion cell, a heat recovery cell, and a circulation cell between the combustion cell and the heat recovery cell, and includes a first partition wall that separates the combustion cell and the circulation cell and whose upper end is located above the fluidized bed, and a second partition wall that separates the circulation cell and the heat recovery cell and whose upper end is located on the upper surface of the fluidized bed, and is filled with a fluidized medium, A fluidized air supply unit located at the bottom of the fluidized bed is provided, which injects fluidized air into the fluidized bed such that the empty velocity of the combustion cell is greater than the empty velocity of the circulation cell and the heat recovery cell, causing the fluidized medium of the combustion cell to flow to the circulation cell below the first partition wall, the fluidized medium of the circulation cell to flow to the heat recovery cell above the second partition wall, and the fluidized medium of the heat recovery cell to move to the combustion cell below the second and first partition walls. A fluidized bed furnace is provided, having a combustion body input section that supplies the combustion body, which is located in the lower part of the fluidized bed section, to the fluidized bed. The fluidized bed furnace further includes an additional air supply device that injects additional air for adjusting the in-bed air ratio downwards toward the area directly above the combustion cell in the fluidized bed at an injection velocity greater than the empty velocity of the combustion cell. Combustion equipment equipped with an additional air supply device.

2. The fluidized bed furnace has a free board section for secondary combustion formed above the fluidized bed section, The additional air supply device includes an additional air supply unit having an additional air supply port between the secondary combustion air supply unit of the freeboard section and the upper surface of the fluidized bed. Combustion equipment equipped with the additional air supply device described in claim 1.

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