Exhaust gas treatment equipment

Abstract

Provided is an exhaust gas treatment facility that is capable of desulfurizing and / or desalinizing in a furnace while suppressing running costs and that can reduce risks to workers. [Solution] An exhaust gas treatment facility (3) that neutralizes acidic gas components contained in combustion exhaust gas generated by the combustion of materials to be combusted in a stoker-type combustion furnace (2), and is equipped with a neutralizing agent injection means (60) that injects a neutralizing agent containing powdered limestone into the furnace of the stoker-type combustion furnace (2). The stoker-type combustion furnace (2) includes a main combustion chamber (11) in which the materials to be combusted are burned while being moved sequentially through a drying stage, a combustion stage, and a post-combustion stage, and it is preferable that the neutralizing agent injection means (60) is configured to inject the neutralizing agent toward the drying stage and / or the combustion stage in the main combustion chamber (11).

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas treatment facility and an exhaust gas treatment method for neutralizing acid gas components contained in combustion exhaust gas generated in association with the combustion of materials to be combusted in a stoker-type combustion furnace. [Background technology]

[0002] BACKGROUND ART A technique for desulfurizing a material to be burned in a stoker-type combustion furnace by mixing slaked lime or quicklime with the material and burning the mixture is known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses that acid gases (HCl, SOx) in combustion exhaust gas generated by combustion in a combustion furnace (incinerator) are removed by injecting hydrated lime into the combustion exhaust gas on the upstream side of the exhaust gas flow of a dust collector that is installed midway through the flow path of the combustion exhaust gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-131197 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, fly ash containing unreacted slaked lime is captured in a dust collector, and some or all of the captured fly ash is recycled and reused as an additive to the material to be combusted. In addition to the fly ash, separately prepared slaked lime and / or quicklime are added to the material to be combusted as needed. The material to be combusted containing unreacted slaked lime, etc., is then burned in a combustion furnace, enabling in-furnace desulfurization by the unreacted slaked lime, etc.

[0006] However, slaked lime poses the risk of injury if it comes into contact with the skin or mucous membranes, and quicklime reacts violently with water, creating the risk of fire and burns, making it difficult to handle. Furthermore, both slaked lime and quicklime are expensive, which increases the running costs of flue gas treatment equipment.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an exhaust gas treatment facility and an exhaust gas treatment method that are capable of desulfurizing and / or demineralizing in a furnace while keeping running costs low and reducing the risk to workers. [Means for solving the problem]

[0008] The characteristic configuration of the exhaust gas treatment equipment according to the present invention for solving the above problems is as follows: An exhaust gas treatment facility that neutralizes acid gas components contained in combustion exhaust gas generated by the combustion of materials in a stoker-type combustion furnace, The stoker-type combustion furnace is provided with a neutralizing agent injection means for injecting a neutralizing agent containing powdered limestone into the furnace.

[0009] In this flue gas treatment system, a neutralizing agent containing powdered limestone is injected into the stoker-type combustion furnace by the neutralizing agent injection means, dispersing and suspending the powdered limestone in the combustion exhaust gas within the furnace. This allows for efficient thermal decomposition (calcination reaction) of limestone within the furnace, and also allows for efficient contact between quicklime produced by the limestone calcination reaction and acidic gas components (SOx, HCl) in the combustion exhaust gas. As a result, desulfurization and / or demineralization can be achieved within the furnace through the neutralization reaction between the quicklime and the acidic gas. Compared to hydrated lime and quicklime, which have traditionally been used as desulfurization / desalting agents, limestone is not only inexpensive but also safe and stable. This allows for desulfurization and / or demineralization within the furnace while reducing running costs and risk to workers. Note that, in this specification, "desalting" refers to the removal of hydrogen chloride from gas (combustion exhaust gas).

[0010] In the exhaust gas treatment equipment according to the present invention, The neutralizing agent blowing means is preferably configured to blow the neutralizing agent by pneumatic transport.

[0011] According to the exhaust gas treatment equipment of this configuration, the neutralizing agent can be easily injected into the furnace with a simple and inexpensive configuration.

[0012] In the exhaust gas treatment equipment according to the present invention, a heat recovery means for recovering heat from the combustion exhaust gas; It is preferable that the heat recovery means is configured to reduce the temperature of the combustion exhaust gas to a temperature at which quicklime turns into slaked lime through a hydration reaction.

[0013] In the flue gas treatment system of this configuration, when heat is recovered by the heat recovery means from the combustion exhaust gas containing quicklime produced by the thermal decomposition of limestone injected into the furnace by the neutralizing agent injection means, the temperature of the combustion exhaust gas is reduced to a temperature at which the quicklime is converted into slaked lime through a hydration reaction. As a result, slaked lime is produced through a hydration reaction between the moisture contained in the combustion exhaust gas and the quicklime, and desulfurization and / or demineralization are achieved through a neutralization reaction caused by contact between the slaked lime and the acidic gas components in the combustion exhaust gas. In this way, in addition to the desulfurization and / or demineralization effect of the quicklime produced in the furnace, the desulfurization and / or demineralization effect of the slaked lime produced by the heat recovery means can be obtained, making it possible to more effectively remove the acidic gas components in the combustion exhaust gas.

[0014] In the exhaust gas treatment equipment according to the present invention, The 50% particle size (D50) of the limestone in terms of volume cumulative distribution is preferably 10 to 1000 μm.

[0015] A small 50% particle size (D50) based on the volumetric distribution of limestone makes it easier to suspend powdered limestone injected into a stoker-type combustion furnace by a neutralizing agent injection means, shortens the time required for limestone pyrolysis, and increases the rate of quicklime production. However, an excessively small D50 can lead to problems such as difficulty in handling, increased risk of dust inhalation by workers, and increased costs for crushing. On the other hand, a large D50 increases the inertial force of the limestone injected into the furnace, extending its linear travel distance and allowing the limestone to be injected over a wider area within the furnace. However, an excessively large D50 makes it difficult to suspend the limestone within the furnace. With this type of exhaust gas treatment equipment, D50 is set within an appropriate range, preventing problems such as difficulties with handling, making it possible to easily float limestone over a wide area within the furnace, and also shortening the time required for the thermal decomposition of limestone, thereby increasing the rate of quicklime production.

[0016] In the exhaust gas treatment equipment according to the present invention, The stoker-type combustion furnace includes a main combustion chamber in which the material to be combusted is combusted while being sequentially moved to a drying stage, a combustion stage, and a post-combustion stage, The neutralizing agent injection means is preferably configured to inject the neutralizing agent toward the drying stage and / or the combustion stage in the main combustion chamber.

[0017] With this type of exhaust gas treatment equipment, the neutralizing agent is injected toward the drying stage in the main combustion chamber, where the materials to be burned are dried at high temperatures, and / or toward the combustion stage, where combustion is most active, so that the thermal decomposition of limestone can proceed more efficiently within the furnace.

[0018] In the exhaust gas treatment equipment according to the present invention, The stoker-type combustion furnace includes a main combustion chamber in which the material to be combusted is moved by an annular grate and combusted on the annular grate, The neutralizing agent injection means is preferably configured to inject the neutralizing agent toward the annular grate in the main combustion chamber.

[0019] According to the exhaust gas treatment equipment of this configuration, the neutralizing agent is blown toward the annular grate body in the main combustion chamber, so that the thermal decomposition of limestone in the furnace can proceed more efficiently.

[0020] In the exhaust gas treatment equipment according to the present invention, The stoker-type combustion furnace includes a secondary combustion chamber connected to a main combustion chamber in which the material to be combusted is moved and combusted, The neutralizing agent injection means is preferably configured to inject the neutralizing agent toward the secondary combustion chamber.

[0021] In the exhaust gas treatment equipment of this configuration, a neutralizing agent is injected into the secondary combustion chamber to further completely burn unburned gases and other substances remaining in the main combustion chamber. This allows the acidic gas components in the combustion exhaust gas to be removed by a neutralization reaction between the quicklime produced by the thermal decomposition of limestone in the secondary combustion chamber and the acidic gas components in the combustion exhaust gas.

[0022] In the exhaust gas treatment equipment according to the present invention, a cooling tower that cools the combustion exhaust gas by spraying water, It is preferable that the temperature of the combustion exhaust gas is reduced in the temperature reducing tower to a temperature at which quicklime turns into slaked lime through a hydration reaction.

[0023] In this flue gas treatment system, the combustion exhaust gas, containing unreacted quicklime from the quicklime produced by the thermal decomposition of limestone injected into the furnace by the neutralizing agent injection means, is cooled in the temperature-reducing tower to a temperature at which the quicklime turns into slaked lime through a hydration reaction, and water sprayed in the temperature-reducing tower is applied to the quicklime. As a result, the quicklime turns into slaked lime through a hydration reaction (slaked reaction), and is desulfurized and / or demineralized by a neutralization reaction caused by contact between the slaked lime and the acidic gas components in the combustion exhaust gas. In this way, in addition to the desulfurization and / or demineralization effect of the quicklime produced in the furnace, the desulfurization and / or demineralization effect of the slaked lime produced in the temperature-reducing tower can be obtained, making it possible to more effectively remove acidic gas components from the combustion exhaust gas.

[0024] In the exhaust gas treatment equipment according to the present invention, a concentration detection means for detecting the concentration of the acidic gas component; a control means for controlling the amount of the neutralizing agent injected by the neutralizing agent injection means based on the detection result of the concentration detection means; It is preferable to have:

[0025] According to the exhaust gas treatment equipment of this configuration, the amount of neutralizing agent injected by the neutralizing agent injection means is controlled based on the detection results of the concentration detection means that detects the concentration of acidic gas components, making it possible to inject an appropriate amount of neutralizing agent into the furnace at the appropriate timing, thereby reliably removing acidic gas components from the combustion exhaust gas while reducing running costs.

[0026] In the exhaust gas treatment equipment according to the present invention, a recovery means for recovering the unreacted neutralizing agent contained in the combustion exhaust gas, It is preferable that the neutralizing agent recovered by the recovery means be blown into the stoker-type combustion furnace.

[0027] According to the exhaust gas treatment equipment of this configuration, the unreacted neutralizing agent recovered by the recovery means is blown into the stoker-type combustion furnace, so that the amount of neutralizing agent used can be reduced by making effective use of the unreacted neutralizing agent.

[0028] In the exhaust gas treatment equipment according to the present invention, It is preferable to further include a pulverizer that pulverizes the neutralizing agent before it is injected into the stoker-type combustion furnace.

[0029] With this configuration of exhaust gas treatment equipment, it is possible to crush a neutralizing agent containing relatively inexpensive, coarse-grained limestone in a crusher and use it as a neutralizing agent containing fine-grained limestone, which can reduce total costs in the long term compared to purchasing and using relatively expensive, fine-grained limestone.

[0030] Next, the characteristic configuration of the exhaust gas treatment method according to the present invention for solving the above problems is as follows: A flue gas treatment method for neutralizing acid gas components contained in combustion exhaust gas generated by the combustion of materials to be combusted in a stoker-type combustion furnace, comprising: The method further includes a neutralizing agent injection step of injecting a neutralizing agent containing powdered limestone into the stoker-type combustion furnace.

[0031] According to the flue gas treatment method of this configuration, a neutralizing agent containing powdered limestone, which is cheaper, safer, and more stable than hydrated lime or quicklime that have conventionally been used as desulfurization / desalting agents, is injected into the stoker-type combustion furnace in the neutralizing agent injection step, making it possible to desulfurize and / or desalt the furnace while keeping running costs down and reducing the risk to workers. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a waste incineration treatment facility equipped with an exhaust gas treatment facility according to one embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a schematic configuration of a biomass combustion treatment facility equipped with an exhaust gas treatment system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be described below with reference to the drawings. However, the present invention is not intended to be limited to the embodiments described below or the configurations shown in the drawings.

[0034] <Overall structure> Fig. 1 is a block diagram showing the schematic configuration of a waste incineration treatment facility 1 equipped with an exhaust gas treatment system 3 according to one embodiment of the present invention. As shown in Fig. 1, the waste incineration treatment facility 1 is equipped with a stoker-type incineration furnace 2 (hereinafter simply referred to as "incineration furnace 2") that combusts waste (material to be combusted) such as municipal solid waste, and also with an exhaust gas treatment system 3 that treats combustion exhaust gas generated as the waste is combusted in the incineration furnace 2.

[0035] <Combustion furnace> The combustion furnace 2 includes a furnace body 20 having a main combustion chamber 11 in which waste is burned while being moved by a stoker 10 .

[0036] A waste supply device 15 is disposed on one side (the left side in FIG. 1) of the furnace body 20 to supply the waste received via the hopper 13 and the chute 14 into the furnace body 20. The waste supply device 15 is a pusher-type supply device that pushes the waste in the chute 14 into the furnace body 20 by the reciprocating motion of a pusher 15a. The pusher 15a is reciprocated by a pusher drive device 15b such as a hydraulic cylinder.

[0037] <Stalker> The stoker 10 is disposed below the furnace body 20 so as to be able to receive waste supplied from the waste supply device 15, and is a stepped stoker in which movable grates and fixed grates are arranged alternately in a stepped pattern. The stoker 10 includes a drying stoker 16 that forms a drying stage, a combustion stoker 17 that forms a combustion stage, and a post-combustion stoker 18 that forms a post-combustion stage, and these drying stoker 16, combustion stoker 17, and post-combustion stoker 18 are arranged in this order from upstream to downstream in the waste feed direction.

[0038] A primary combustion air supply device 21 for supplying primary combustion air is attached to the stoker 10. The primary combustion air supply device 21 includes a blower 30 that blows out primary combustion air, and is configured to supply the primary combustion air from the blower 30 to the drying stoker 16, the combustion stoker 17, and the post-combustion stoker 18 via a primary combustion air main supply pipe 31 and a first branch pipe 31a, a second branch pipe 31b, and a third branch pipe 31c branching from the primary combustion air main supply pipe 31.

[0039] A secondary combustion chamber 12 is connected to the main combustion chamber 11 at the upper side of the furnace body 20 for burning unburned gases and the like remaining in the main combustion chamber 11. Secondary combustion air is supplied to the secondary combustion chamber 12 by a secondary combustion air supply device 22. The secondary combustion air supply device 22 includes an air injection nozzle 41 attached to the wall of the secondary combustion chamber 12 so as to be able to inject secondary combustion air toward the secondary combustion chamber 12, a blower 42 for blowing secondary combustion air, and a secondary combustion air supply pipe 43 arranged to connect the air injection nozzle 41 and the blower 42. The secondary combustion air sent out from the blower 42 is supplied into the secondary combustion chamber 12 via the secondary combustion air supply pipe 43 and the air injection nozzle 41. A flow rate adjustment damper 44 is installed in the secondary combustion air supply pipe 43 to adjust the amount of secondary combustion air supplied into the secondary combustion chamber 12.

[0040] <Exhaust gas treatment equipment> The exhaust gas treatment facility 3 treats the combustion exhaust gas generated when waste is burned in the combustion furnace 2, and is equipped with a heat recovery means 51, a temperature reducing tower 52, a filter-type dust collector 53, an induced draft fan 54, and a chimney 55, which are arranged in the exhaust path of the combustion exhaust gas. In the exhaust gas treatment facility 3, the combustion exhaust gas generated in the combustion furnace 2 is sent in turn to the heat recovery means 51, the temperature reducing tower 52, and the filter-type dust collector 53 by the induction action of the induced draft fan 54.

[0041] The heat recovery means 51 recovers heat from the combustion exhaust gas and includes a boiler 56 and an economizer 57. The boiler 56 generates steam using the heat of the combustion exhaust gas, and the economizer 57 heats water to be supplied to the boiler 56 using the residual heat of the combustion exhaust gas. Note that the combustion boiler facility including the combustion furnace 2 and the boiler 56 may be configured to generate electricity by driving a generator using a turbine (not shown) connected to the boiler 56.

[0042] <Decoupling tower> The temperature reducing tower 52 includes a tower body into which the combustion exhaust gas from which heat has been recovered by the heat recovery means 51 is introduced, and is configured to spray water onto the combustion exhaust gas introduced into the tower body and reduce the temperature of the combustion exhaust gas by the heat of vaporization of the water. The temperature reducing tower 52 reduces the temperature of the combustion exhaust gas to 500°C or less, which is suitable for the hydration reaction (digestion reaction), and in particular to below the heat resistance temperature (approximately 200°C) of the filter cloth used in the filter-type dust collector 53.

[0043] The filter dust collector 53 is configured to capture and remove fly ash (dust) and other substances contained in the combustion exhaust gas by passing the combustion exhaust gas through a filter cloth. The fly ash and other substances collected by the filter dust collector 53 are sequentially discharged via a screw conveyor, rotary valve, or other device (not shown) and transported to a fly ash recovery section 58. The combustion exhaust gas from which the fly ash and other substances have been removed by the filter dust collector 53 is discharged to the outside via a chimney 55 by an induced draft fan 54.

[0044] <Neutralizing agent injection means> The exhaust gas treatment facility 3 further includes a neutralizing agent injection means 60 for injecting a neutralizing agent containing powdered limestone into the combustion exhaust gas to neutralize acidic gas components contained in the combustion exhaust gas. The neutralizing agent injection means 60 includes a first neutralizing agent injection means 60A for injecting a neutralizing agent into the main combustion chamber 11 of the combustion furnace 2, and a second neutralizing agent injection means 60B for injecting a neutralizing agent into the secondary combustion chamber 12 of the combustion furnace 2.

[0045] <First Neutralizing Agent Injection Means> The first neutralizing agent injection means 60A includes a first neutralizing agent injection nozzle 61 attached to the furnace body 20 so as to be able to inject the neutralizing agent toward the drying stoker 16 and / or the combustion stoker 17 in the main combustion chamber 11, and a powder transfer device 65A that transfers the neutralizing agent to the first neutralizing agent injection nozzle 61 by pneumatic transport.

[0046] The powder transfer device 65A includes a transfer pipe 70, a first compressor 71, a second compressor 72, a hopper 73, a rotary valve 74, a control valve 75, and an aspirator 76.

[0047] A first neutralizing agent injection nozzle 61 is connected to the tip side of the transfer pipe 70, and a first compressor 71 is connected to the base end side of the transfer pipe 70. A hopper 73 and a rotary valve 74 are disposed in the portion of the transfer pipe 70 near the base end.

[0048] Hopper 73 temporarily stores a neutralizing agent containing powdered limestone supplied from limestone silo 77. Hopper 73 is provided with a rotary valve 74 so that it can receive the neutralizing agent delivered from hopper 73. Rotary valve 74 is disposed so that it can supply the neutralizing agent stored in hopper 73 to a mixer 78 provided near the base end of transfer pipe 70 by rotational driving of a motor. Compressed air from first compressor 71 is supplied to mixer 78, and the neutralizing agent is supplied via hopper 73 and rotary valve 74. The mixed fluid of compressed air and neutralizing agent mixed in mixer 78 is then pressure-fed through transfer pipe 70.

[0049] An aspirator 76 is provided at an appropriate position along the length of the transfer pipe 70. A plurality of aspirators 76 (three in this example) are provided at required locations along the length of the transfer pipe 70. A compressed air main supply pipe 79 is attached to the transfer pipe 70. A second compressor 72 is connected to the base end of the compressed air main supply pipe 79, and compressed air from the second compressor 72 is supplied to each aspirator 76 via the compressed air main supply pipe 79 and branch pipes 79a, 79b, and 79c branching off from the compressed air main supply pipe 79. A control valve 75 is provided near the base end of the compressed air main supply pipe 79 to adjust the amount of compressed air supplied from the second compressor 72 to each aspirator 76.

[0050] The aspirator 76 has a suction port (not shown) for sucking in atmospheric air, and also has an internal diffuser section (not shown), and is configured to suck in atmospheric air as secondary air through the suction port while generating a powerful flow of air that is sprayed toward the tip of the transfer tube 70.

[0051] In the first neutralizing agent injection means 60A, in order to maintain a compressed air pressure commensurate with the resistance loss within the transfer pipe 70, compressed air is supplied as a driving fluid from the second compressor 72 via a control valve 75, a main compressed air supply pipe 79, and each branch pipe 79a, 79b, 79c to each of a plurality of aspirators 76 arranged at appropriate locations along the transfer pipe 70.The mixed fluid of compressed air and neutralizing agent pressurized within the transfer pipe 70 is sequentially sucked in and sprayed toward the tip of the transfer pipe 70 due to the ejector effect of each aspirator 76, and the neutralizing agent is sprayed through the first neutralizing agent injection nozzle 61 toward the drying stoker 16 and / or the combustion stoker 17 in the main combustion chamber 11 and blown into the main combustion chamber 11.

[0052] <Second Neutralizing Agent Injection Means> The second neutralizing agent injection means 60B includes a second neutralizing agent injection nozzle 62 attached to a wall of the secondary combustion chamber 12 so as to be able to inject the neutralizing agent toward the secondary combustion chamber 12, and a powder transfer device 65B that transfers the neutralizing agent to the second neutralizing agent injection nozzle 62 by pneumatic transport. The powder transfer device 65B has the same configuration as the powder transfer device 65A in the first neutralizing agent injection means 60A. Therefore, the same reference numerals are used in FIG. 1 and detailed description thereof will be omitted.

[0053] In the second neutralizing agent injection means 60B, when compressed air is supplied as a driving fluid from the second compressor 72 to each of the multiple aspirators 76 via the control valve 75, the compressed air main supply pipe 79, and each branch pipe 79a, 79b, 79c, the mixed fluid of compressed air and neutralizing agent pressurized within the transfer pipe 70 is sequentially sucked and ejected toward the tip of the transfer pipe 70 due to the ejector effect of each aspirator 76, and the neutralizing agent is sprayed toward the secondary combustion chamber 12 through the second neutralizing agent injection nozzle 62 and blown into the secondary combustion chamber 12.

[0054] If the 50% particle size (D50) of the limestone contained in the neutralizing agent injected into the combustion furnace 2 (main combustion chamber 11, secondary combustion chamber 12) by the neutralizing agent injection means 60 is small, the powdered limestone injected into the furnace can be easily suspended within the furnace, the time required for thermal decomposition of the limestone can be shortened, and the rate of quicklime production can be increased. However, if the D50 is too small, problems such as difficulty in handling, increased risk of dust inhalation by workers, and increased costs for crushing can occur. On the other hand, if the D50 is large, the inertial force of the limestone injected into the combustion furnace 2 can be increased, extending the distance traveled in a straight line, and allowing the limestone to be injected over a wider area within the furnace. However, if the D50 is too large, it becomes difficult to suspend the limestone within the furnace.

[0055] Therefore, D50 is preferably 10 to 1000 μm, more preferably 50 to 500 μm, even more preferably 150 to 300 μm, and particularly preferably 180 to 260 μm. By setting D50 within an appropriate range, limestone can be easily suspended over a wide area within the combustion furnace 2 while preventing problems such as difficulties in handling, and the production rate of quicklime can be increased by shortening the time required for the thermal decomposition of limestone.

[0056] The exhaust gas treatment facility 3 further includes a control device 80, a first concentration meter 85, and a second concentration meter 86. The control device 80 is mainly composed of a computer, performs predetermined calculation processing according to a predetermined program, and transmits predetermined control signals based on the calculation results to the flow rate adjustment damper 44, the rotary valve 74, and the control valve 75. The first concentration meter 85 detects the concentration of acid gas components contained in the combustion exhaust gas generated as a result of the combustion of waste in the main combustion chamber 11, and the second concentration meter 86 detects the concentration of acid gas components contained in the combustion exhaust gas in the secondary combustion chamber 12, and the detection signals of the concentration meters 85, 86 are transmitted to the control device 80.

[0057] In the waste incineration treatment facility 1 configured as described above, waste pushed into the furnace body 20 of the incineration furnace 2 by the waste supply device 15 is first sent to the drying stoker 16. The waste sent to the drying stoker 16 is dried by primary combustion air from the primary combustion air supply device 21 and radiant heat from the main combustion chamber (primary combustion chamber) 11. The dried waste in the drying stoker 16 is ignited by radiant heat from the main combustion chamber 11, and the ignited waste is sent to the combustion stoker 17, where a portion is combusted, and the remaining unburned waste is sent to the post-combustion stoker 18. The unburned waste is combusted in the post-combustion stoker 18, and the combustion ash remaining after combustion is discharged to the outside via the chute 20a provided at the bottom end of the furnace body 20. Meanwhile, unburned gas generated in the main combustion chamber 11 is secondarily combusted in the secondary combustion chamber 12 using secondary combustion air from the secondary combustion air supply device 22.

[0058] In the exhaust gas treatment equipment 3, the first neutralizing agent injection means 60A supplies compressed air as a driving fluid to each aspirator 76 from the second compressor 72 via the control valve 75, the compressed air supply main pipe 79, and each branch pipe 79a, 79b, 79c, thereby sequentially sucking in and spraying the mixed fluid of compressed air and neutralizing agent pressurized within the transfer pipe 70 toward the tip side of the transfer pipe 70, and injecting the neutralizing agent through the first neutralizing agent injection nozzle 61 toward the drying stoker 16 and / or the combustion stoker 17 in the main combustion chamber 11, thereby blowing it into the main combustion chamber 11.

[0059] The powdered limestone contained in the neutralizing agent injected into the main combustion chamber 11 is dispersed and suspended in the combustion exhaust gas above the drying stoker 16 and / or combustion stoker 17. Within the main combustion chamber 11, the atmosphere above the drying stoker 16 and / or combustion stoker 17 is approximately 850 to 1100°C, which is suitable for the thermal decomposition (burning reaction) of limestone. The stirring action caused by the combustion flow is vigorous, allowing the thermal decomposition of limestone to proceed efficiently within the main combustion chamber 11. The quicklime produced by the limestone burning reaction can be efficiently brought into contact with the acidic gas components (SOx, HCl) in the combustion exhaust gas. As a result, desulfurization and / or demineralization can be achieved within the main combustion chamber 11 through the neutralization reaction between the quicklime and the acidic gases. In this way, limestone, which is cheaper and safer and more stable than slaked lime or quicklime, is used as a desulfurization / desalting agent, and a neutralizing agent containing limestone is injected into the main combustion chamber 11, thereby making it possible to desulfurize and / or desalt the main combustion chamber 11 while keeping running costs down and also reducing the risk to workers.

[0060] The control device 80 calculates the concentration of acidic gas components contained in the combustion exhaust gas in the main combustion chamber 11 based on the detection signal from the first concentration meter 85, and sends a predetermined control signal based on the calculation result to the rotary valve 74 and / or the control valve 75 to control the amount of neutralizing agent injected by the first neutralizing agent injection means 60A. This makes it possible to inject an appropriate amount of neutralizing agent into the main combustion chamber 11 at an appropriate timing, and it is possible to reliably remove acidic gas components from the combustion exhaust gas while keeping running costs down. Here, by controlling the rotary valve 74 and / or the control valve 75 by the control device 80, the initial jet velocity of the neutralizing agent when injected by the first neutralizing agent injection means 60A is set to 15 to 60 m / sec, more preferably 25 to 55 m / sec, and even more preferably 45 to 50 m / sec (27 m / sec in this example), so that the neutralizing agent can be widely dispersed and suspended within the main combustion chamber 11, and a stirring effect can be obtained (the same applies to the injection operation by the second neutralizing agent injection means 60B).

[0061] In the exhaust gas treatment equipment 3, the second neutralizing agent injection means 60B supplies compressed air as a driving fluid to each suction device 76 from the second compressor 72 via the control valve 75, the compressed air supply main pipe 79, and each branch pipe 79a, 79b, 79c, thereby sequentially sucking and spraying the mixed fluid of compressed air and neutralizing agent pressurized within the transfer pipe 70 toward the tip side of the transfer pipe 70, and injecting the neutralizing agent into the secondary combustion chamber 12 through the second neutralizing agent injection nozzle 62.

[0062] The powdered limestone contained in the neutralizing agent injected into the secondary combustion chamber 12 is dispersed and suspended in the combustion exhaust gas within the secondary combustion chamber 12. The atmosphere within the secondary combustion chamber 12 is maintained at 800°C or higher to decompose dioxins, and the combustion flow provides active stirring, allowing the thermal decomposition of limestone to proceed efficiently within the secondary combustion chamber 12 and allowing the quicklime produced by the calcination reaction of the limestone to efficiently come into contact with the acidic gas components in the combustion exhaust gas. As a result, desulfurization and / or demineralization can be achieved within the secondary combustion chamber 12 through a neutralization reaction between the quicklime and the acidic gases. This allows the remaining acidic gas components in the combustion exhaust gas to be removed.

[0063] The control device 80 calculates the concentration of the acidic gas components contained in the combustion exhaust gas in the secondary combustion chamber 12 based on the detection signal from the second concentration meter 86, and sends a predetermined control signal based on the calculation result to the rotary valve 74 and / or the control valve 75 to control the amount of neutralizing agent injected by the second neutralizing agent injection means 60B. This makes it possible to inject an appropriate amount of neutralizing agent into the secondary combustion chamber 12 at an appropriate timing, and it is possible to reliably remove the remaining acidic gas components in the combustion exhaust gas while keeping running costs down.

[0064] In the exhaust gas treatment facility 3, the combustion exhaust gas after being neutralized by the neutralizing agent injection means 60 is sent in turn to the heat recovery means 51, the cooling tower 52 and the filtration type dust collector 53 by the induction action of the induced draft fan 54.

[0065] In the temperature reducing tower 52, water is sprayed onto the combustion exhaust gas from which heat has been recovered by the heat recovery means 51, thereby reducing the temperature of the combustion exhaust gas to below 500°C, which is suitable for the hydration reaction (digestion reaction), and below the heat resistance temperature (approximately 200°C) of the filter cloth used in the filter-type dust collector 53.

[0066] When the combustion exhaust gas containing unreacted quicklime produced by the thermal decomposition of limestone injected into the combustion furnace 2 (main combustion chamber 11, secondary combustion chamber 12) by the neutralizing agent injection means 60 is introduced into the temperature reducing tower 52, the temperature inside the temperature reducing tower 52 is below 500°C, which is suitable for hydration (slaked reaction), and in this example, below 200°C. The unreacted quicklime is converted into slaked lime by hydration when sprayed with water in the temperature reducing tower 52. The slaked lime then comes into contact with the acidic gas components in the combustion exhaust gas, resulting in desulfurization and / or demineralization. In this way, in addition to the desulfurization and / or demineralization effect of the quicklime produced inside the combustion furnace 2, the desulfurization and / or demineralization effect of the slaked lime produced in the temperature reducing tower 52 can be obtained, thereby more effectively removing the acidic gas components in the combustion exhaust gas.

[0067] The quicklime produced by burning limestone in the combustion furnace 2 reduces acidic gas components, particularly HCl, thereby suppressing high-temperature corrosion of the superheater of the boiler 56 and contributing to the production of high-temperature, high-pressure steam.

[0068] In this embodiment, an example is shown in which powder transfer devices 65A, 65B are used as the neutralizing agent injection means 60, which combine a first compressor 71, a second compressor 72, an aspirator 76, etc., and transport powder to the tip side of the transfer tube 70 by the ejector effect of the aspirator 76.However, this is not limited to this, and any powder transfer device structure may be used as long as it can transport powder by air.For example, a powder transfer device that transports powder by using the air flow sent out from a blower may be used.

[0069] In this embodiment, waste such as municipal waste is exemplified as the material to be burned, but there is no particular limitation as long as it is combustible, and it may also be biomass fuel (described later), sludge, etc.

[0070] Although the exhaust gas treatment equipment and the exhaust gas treatment method of the present invention have been described above based on one embodiment, the present invention is not limited to the configuration described in the above embodiment, and the configuration can be appropriately changed within the scope of the gist of the present invention. Specific other embodiments are as follows.

[0071] (Another embodiment 1) In the above embodiment, the temperature reducing tower 52 is not an essential component but an optional component and can be omitted. When the temperature reducing tower 52 is omitted, the temperature of the combustion exhaust gas is reduced by heat recovery in the heat recovery means 51 to a temperature (500°C or lower) suitable for converting quicklime into slaked lime through a hydration reaction. More preferably, the temperature of the combustion exhaust gas is reduced to a temperature (approximately 200°C) or lower than the heat resistance temperature of the filter cloth used in the filter-type dust collector 53. As a result, slaked lime is produced by a hydration reaction between the moisture contained in the combustion exhaust gas and the quicklime, and desulfurization and / or demineralization are achieved by a neutralization reaction caused by contact between the slaked lime and acidic gas components in the combustion exhaust gas. In this way, in addition to the desulfurization and / or demineralization effect of the quicklime produced in the combustion furnace 2, the desulfurization and / or demineralization effect of the slaked lime produced by heat recovery in the heat recovery means 51 can be obtained, thereby more effectively removing acidic gas components from the combustion exhaust gas.

[0072] (Alternative embodiment 2) In the above embodiment, the fly ash collected by the fly ash collection unit 58 (corresponding to the "collection means" of the present invention) contains a neutralizing agent containing unreacted quicklime. Therefore, the fly ash collected by the fly ash collection unit 58 may be supplied to a hopper 73 via a conveying line 100, such as a conveyor, and then injected into the combustion furnace 2 (the main combustion chamber 11 and the secondary combustion chamber 12) by a neutralizing agent injection means 60. In this way, the unreacted neutralizing agent can be circulated and effectively utilized, thereby reducing the amount of neutralizing agent used.

[0073] (Alternative embodiment 3) In the above embodiment, for example, a crusher 101 may be provided in the limestone supply line and / or conveying line 100 from the limestone silo 77 to the hopper 73, so that the neutralizing agent can be crushed before being injected into the combustion furnace 2. This makes it possible to crush a neutralizing agent containing relatively inexpensive, coarse-grained limestone in the crusher and use it as a neutralizing agent containing fine-grained limestone, thereby reducing the total cost in the long term compared to purchasing and using relatively expensive, fine-grained limestone.

[0074] (Alternative embodiment 4) In the above embodiment, an example has been shown in which the second neutralizing agent injection means 60B is provided separately from the secondary combustion air supply device 22, but the present invention is not limited to this, and a hopper 73, a rotary valve 74, and a mixer 78 may be disposed in the secondary combustion air supply pipe 43 between the air injection nozzle 41 and the flow rate control damper 44, and the mixed fluid of the neutralizing agent and secondary combustion air mixed in the mixer 78 may be ejected from the air injection nozzle 41 and injected into the secondary combustion chamber 12. In this way, by adopting a configuration that combines the functions of both the secondary combustion air supply device 22 and the second neutralizing agent injection means 60B, the device configuration can be simplified.

[0075] (Alternative embodiment 5) In the above embodiment, an example was shown in which a neutralizing agent containing powdered limestone was injected into the combustion furnace 2, but this is not limited to this, and a neutralizing agent containing biomass combustion ash that contains a relatively large amount of calcium carbonate or combustion ash that has been carbonated may also be injected.

[0076] (Alternative embodiment 6) FIG. 2 is a block diagram showing a schematic configuration of a biomass combustion treatment facility 201 equipped with an exhaust gas treatment facility 3 according to one embodiment of the present invention. In the above embodiment, an example has been shown in which the exhaust gas treatment facility 3 according to one embodiment of the present invention is applied to a waste combustion treatment facility 1 equipped with a stepped stoker combustion furnace 2, but the present invention is not limited to this. The exhaust gas treatment facility 3 according to one embodiment of the present invention can also be applied to a biomass combustion treatment facility 201 equipped with a traveling stoker combustion furnace 204 (corresponding to the "stoker-type combustion furnace" of the present invention). The biomass combustion treatment facility 201 will be described below using FIG. 2. Note that in the biomass combustion treatment facility 201 shown in FIG. 2, components that are the same as or similar to those in the waste combustion treatment facility 1 shown in FIG. 1 will be denoted by the same reference numerals in the figure, and detailed description thereof will be omitted. The following description will focus on parts unique to the biomass combustion treatment facility 201.

[0077] As shown in FIG. 2, a biomass combustion treatment facility 201 mainly includes a fuel supply machine 202, a fuel conveying device 203, a combustion furnace 204, a boiler 205, and the like. Biomass fuel stored in a biomass fuel supply building (not shown) is transported to the combustion furnace 204 via the fuel supply machine 202 and the fuel conveying device 203, which are composed of a fuel metering feeder (not shown), and is combusted in the combustion furnace 204. The combustion exhaust gas generated by the combustion in the combustion furnace 204 is sent to the boiler 205 and the like by the induction action of an induction fan (not shown), where heat is recovered. The combustion exhaust gas is then cooled in a cooling tower (not shown), dusted in a bag filter (not shown), and released to the outside via a chimney (not shown). Note that "biomass fuel" refers to a biological fuel extracted from organic resources in nature, such as plants and agricultural products, other than fossil fuels. Specifically, biomass fuels include, for example, waste wood, thinnings, driftwood, grass, household waste, sludge, livestock manure, energy crops (agricultural crops), and recycled fuels (pellets and chips) made from these raw materials.

[0078] <Combustion furnace> As shown in Figure 2, the combustion furnace 204 includes a furnace body 210 having a main combustion chamber (primary combustion chamber) 211 and a secondary combustion chamber 212. A fuel input device 215 for inputting biomass fuel into the furnace body 210 is disposed on one side (the left side in Figure 2) of the furnace body 210, and an auxiliary fuel supply device (not shown) for supplying auxiliary fuel having a higher calorific value than the biomass fuel into the furnace body 210 is disposed. A traveling stoker 220 is disposed on the lower side of the furnace body 210, and a primary combustion air supply device 21 for supplying primary combustion air to the traveling stoker 220 is disposed. In the combustion furnace 204, secondary combustion air is supplied to the secondary combustion chamber 212 by a secondary combustion air supply device 22.

[0079] <Fuel injection machine> The fuel input device 215 includes a input device main body 217 and a spray nozzle 218. The input device main body 217 receives the biomass fuel discharged from the discharge port of the fuel conveying device 203, and also receives a portion of the secondary combustion air from the secondary combustion air supply device 22. The fuel input device 215 is configured to input the biomass fuel into the furnace body 210 by spraying the biomass fuel introduced into the input device main body 217 together with the secondary combustion air from the spray nozzle 218 using the secondary combustion air. The fuel input device 215 is configured to vary the flow rate of the secondary combustion air introduced into the input device main body 217 from the secondary combustion air supply device 22. This configuration allows the spray speed to be adjusted when the biomass fuel is input into the furnace body 210. Furthermore, the fuel input device 215 is configured to vary the spray angle of the spray nozzle 218. This configuration allows the spray angle to be adjusted when the biomass fuel is input into the furnace body 210. In this way, by adjusting the radiation speed and radiation angle when biomass fuel is charged into the furnace body 210, the charging position of the biomass fuel relative to the traveling stoker 220 can be adjusted.

[0080] <Traveling Stalker> The traveling stoker 220 is configured by wrapping an annular grate body 223, which is made up of multiple grates rotatably connected to each other in an annular shape, around drive wheels 221 and driven wheels 222 that are arranged at a predetermined interval in the direction in which the biomass fuel is moved inside the furnace body 210. A stoker drive unit 225 that drives the traveling stoker 220 is attached to the traveling stoker 220. The stoker drive unit 225 is configured to include a drive motor, a power transmission mechanism that transmits the rotational power of the drive motor to the drive wheels 221, and the like.

[0081] The traveling stoker 220 is disposed within the furnace body 210 so that the biomass fuel charged by the fuel charger 215 toward the other side (the right side in FIG. 2) of the furnace body 210 can be received by the annular grate body 223. In the traveling stoker 220, the annular grate body 223 is driven to move in an orbital motion by the stoker drive device 225, and the biomass fuel from the fuel charger 215 received by the annular grate body 223 is burned on the annular grate body 223 while moving toward one side (the left side in FIG. 2) of the furnace body 210, and the bottom ash generated by the combustion can be transported to a bottom ash discharge outlet 210a provided at the bottom of one side of the furnace body 210.

[0082] In the exhaust gas treatment equipment 3 in the biomass combustion treatment facility 201 configured as described above, the first neutralizing agent injection means 60A supplies compressed air as a driving fluid to each aspirator 76 from the second compressor 72 via the control valve 75, the compressed air supply main pipe 79, and each branch pipe 79a, 79b, 79c, thereby sequentially sucking in and spraying the mixed fluid of compressed air and neutralizing agent pressurized within the transfer pipe 70 toward the tip side of the transfer pipe 70, and injecting the neutralizing agent through the first neutralizing agent injection nozzle 61 toward the traveling stoker 220 in the main combustion chamber 211, thereby blowing it into the main combustion chamber 211. Furthermore, second neutralizing agent injection means 60B supplies compressed air as a driving fluid to each aspirator 76 from second compressor 72 via control valve 75, compressed air main supply pipe 79, and each branch pipe 79a, 79b, 79c, thereby sequentially sucking and spraying a mixed fluid of compressed air and neutralizing agent pressure-fed within transfer pipe 70 toward the tip side of transfer pipe 70, and injecting the neutralizing agent into secondary combustion chamber 212 through second neutralizing agent injection nozzle 62. Therefore, the same effects as those of the above embodiment can be obtained. [Industrial Applicability]

[0083] The exhaust gas treatment facility and the exhaust gas treatment method of the present invention can be used to neutralize acid gas components contained in the combustion exhaust gas generated in conjunction with the combustion of materials to be combusted in a stoker-type combustion furnace. [Explanation of symbols]

[0084] 2. Combustion furnace (stoker type combustion furnace) 3. Exhaust gas treatment equipment 11 Main combustion chamber 12 Secondary combustion chamber 16 Drying stoker (drying stage) 17 Combustion stoker (combustion stage) 18 Post-combustion stoker (post-combustion stage) 51 Heat recovery means 52 Cooling tower 58 Fly ash collection section (collection means) 60 Neutralizing agent injection means 74 Rotary valve (control means) 75 Control valve (control means) 80 Control device (control means, concentration detection means) 85 First concentration meter (concentration detection means) 86 Second concentration meter (concentration detection means) 101 Crusher 204 Combustion furnace (stoker type combustion furnace) 211 Main combustion chamber 212 Secondary Combustion Chamber 220 Traveling Stalker 223 Annular grate

Claims

1. An exhaust gas treatment facility that neutralizes acid gas components contained in combustion exhaust gas generated by the combustion of materials in a stoker-type combustion furnace, a neutralizing agent injection means for injecting a neutralizing agent containing powdered limestone into the stoker-type combustion furnace; The stoker-type combustion furnace includes a main combustion chamber in which the material to be combusted is combusted while being sequentially moved to a drying stage, a combustion stage, and a post-combustion stage, The neutralizing agent injection means is configured to inject the neutralizing agent toward the drying stage and / or the combustion stage so that the limestone is dispersed and suspended in the combustion exhaust gas above the drying stage and / or the combustion stage in the main combustion chamber.

2. 2. The exhaust gas treatment facility according to claim 1, wherein the neutralizing agent injection means is configured to inject the neutralizing agent by pneumatic transportation.

3. a heat recovery means for recovering heat from the combustion exhaust gas; 3. The exhaust gas treatment facility according to claim 1, wherein the heat recovery means is configured to reduce the temperature of the combustion exhaust gas to a temperature at which quicklime turns into slaked lime through a hydration reaction.

4. 3. The exhaust gas treatment facility according to claim 1, wherein the limestone has a 50% particle size (D50) in a volume cumulative distribution of 10 to 1000 μm.

5. An exhaust gas treatment facility that neutralizes acid gas components contained in combustion exhaust gas generated by the combustion of materials to be combusted in a stoker-type combustion furnace, a neutralizing agent injection means for injecting a neutralizing agent containing powdered limestone into the stoker-type combustion furnace; The stoker-type combustion furnace includes a main combustion chamber in which the material to be combusted is moved by an annular grate and combusted on the annular grate, The neutralizing agent injection means is configured to inject the neutralizing agent toward the annular grate so that the limestone is dispersed and suspended in the combustion exhaust gas above the annular grate in the main combustion chamber.

6. The stoker-type combustion furnace includes a secondary combustion chamber connected to a main combustion chamber in which the material to be combusted is moved and combusted, 3. The exhaust gas treatment facility according to claim 1, wherein the neutralizing agent injection means is configured to inject the neutralizing agent toward the secondary combustion chamber.

7. a cooling tower that cools the combustion exhaust gas by spraying water, 3. The flue gas treatment facility according to claim 1, wherein the flue gas is cooled in the cooling tower to a temperature at which quicklime turns into slaked lime through a hydration reaction.

8. a concentration detection means for detecting the concentration of the acidic gas component; a control means for controlling the amount of the neutralizing agent injected by the neutralizing agent injection means based on the detection result of the concentration detection means; The exhaust gas treatment facility according to claim 1 or 2, comprising:

9. a recovery means for recovering the unreacted neutralizing agent contained in the combustion exhaust gas, 3. The exhaust gas treatment facility according to claim 1, wherein the neutralizing agent recovered by the recovery means is blown into the stoker-type combustion furnace.

10. 3. The exhaust gas treatment facility according to claim 1, further comprising a pulverizer that pulverizes the neutralizing agent before it is injected into the stoker-type combustion furnace.

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