Blowing device

Abstract

To restrain an alkali agent from adhering to a device for blowing the alkali agent into exhaust gas.SOLUTION: A blowing device is provided in a flue through which exhaust gas discharged from a waste incinerator flows, and comprises a first pipe inside which steam flows, a second pipe inside which the first pipe is arranged, and a nozzle continuous with the first pipe. Air containing an alkali agent flows between an inner surface of the second pipe and an outer surface of the first pipe. The nozzle comprises a contraction part whose cross-sectional area is contracted toward a tip. The contraction part comprises an opening for blowing the steam into the exhaust gas discharged from the waste incinerator.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a blowing device. [Background technology]

[0002] As a method for purifying combustion exhaust gas generated in an incinerator, acid gases (HCl, SO) are removed by an alkaline agent injected into the combustion exhaust gas. x There is a dry method for removing acid gases, in which reaction products generated by an alkaline agent are collected using a bag filter. In the dry method, it is known that increasing the moisture concentration in the combustion exhaust gas increases the reaction rate between the alkaline agent and the acid gas, thereby improving removal efficiency. However, a large amount of steam is required to increase the moisture concentration of the entire exhaust gas. On the other hand, a steam lance, for example, as disclosed in Patent Document 1, is a technology that improves removal efficiency using a small amount of steam.

[0003] This steam lance consists of two pipes arranged coaxially; steam is sent through the inner pipe to its opening, and slaked lime is sent between the outer and inner pipes to the opening of the outer pipe. A conical valve that widens towards the tip is installed at the opening of the inner pipe, and steam is blown out from the opening, expanding outwards while entraining air containing slaked lime, until it comes into contact with the slaked lime. The mixed gas of steam and air containing slaked lime reaches a water vapor partial pressure greater than the saturated vapor pressure at that temperature, forming a temporary condensed water film on the surface of the slaked lime. The removal efficiency is improved through the rapid dissolution of acid gases into the condensed water film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-152347 Summary of the Invention [Problem to be solved by the invention]

[0005] At the tip of the steam lance disclosed in Patent Document 1, steam is sprayed toward the slaked lime. However, the steam causes the water to condense and promote carbonation of the slaked lime, which causes the slaked lime to adhere to the tip of the inner pipe. If a large amount of slaked lime adheres, it will cause an obstruction to the supply of slaked lime.

[0006] The present invention has been made in view of the above, and has an object to prevent the alkaline agent from adhering to a device that injects the alkaline agent into exhaust gas. [Means for solving the problem]

[0007] A blowing device according to one aspect of the present invention is a blowing device installed in a flue through which exhaust gas discharged from a waste incinerator flows, and has a first pipe through which water vapor flows, a second pipe within which the first pipe is arranged, and a nozzle connected to the first pipe, wherein air containing an alkaline agent flows between the inner surface of the second pipe and the outer surface of the first pipe, and the nozzle has a contracting section whose cross-sectional area contracts toward the tip, and the contracting section has an opening through which the water vapor is blown into the exhaust gas discharged from the waste incinerator.

[0008] In the blowing device according to the present invention, the nozzle may include an expanding portion whose cross-sectional area expands toward a tip thereof, and the nozzle may include the contracting portion on the tip side of the expanding portion.

[0009] In the blowing device according to the present invention, the contracting portion may have an outer surface that is hemispherical.

[0010] In the blowing device according to the present invention, the water vapor may be at a temperature of 130° C. or higher in the nozzle.

[0011] The blowing device according to the present invention may further include a rod in contact with the second pipe, and a vibrator that vibrates the rod.

[0012] In the blowout device according to the present invention, the diameter of the opening of the nozzle through which the steam is blown out may be smaller than the inner diameter of the first pipe. [Effects of the Invention]

[0013] According to the present invention, it is possible to prevent the alkaline agent from adhering to a device that injects the alkaline agent into exhaust gas. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of an exhaust gas treatment device according to an embodiment and a waste incineration system equipped with the exhaust gas treatment device. [Figure 2] FIG. 2 is a cross-sectional view of the upstream flue at a position where the blowout section is disposed. [Figure 3] FIG. 3 is a schematic cross-sectional view of the blowing device. [Figure 4A] FIG. 4A is a schematic diagram of a cross section of a nozzle. [Figure 4B] FIG. 4B is a schematic diagram of a cross section of the nozzle. [Figure 5] FIG. 5 is a graph showing the relationship between the thickness of the first layer and the surface temperature of the first layer. [Figure 6] FIG. 6 is a cross-sectional view showing a modified example of the nozzle arrangement. [Figure 7A] FIG. 7A is a cross-sectional view of a nozzle according to a modified example. [Figure 7B] FIG. 7B is a cross-sectional view of a nozzle according to a modified example. [Figure 7C] FIG. 7C is a cross-sectional view of a nozzle according to a modified example. [Figure 7D] FIG. 7D is a cross-sectional view of a nozzle according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0016] 1 is a block diagram showing a schematic configuration of an exhaust gas treatment device 100 according to an embodiment of the present invention and a waste incineration system 1000 including the exhaust gas treatment device 100. The exhaust gas treatment device 100 is provided between a waste incinerator 1 and a chimney 2.

[0017] The waste incinerator 1 is an incinerator that incinerates waste. Exhaust gas generated in the waste incinerator 1 flows to a boiler 1A. The boiler 1A generates steam by heating water that has been preheated in an economizer 1B (described later) with the exhaust gas that flows from the waste incinerator 1. The steam generated in the boiler 1A flows to a steam turbine 21.

[0018] The steam turbine 21 is connected to a generator (not shown), and is rotated by steam sent from the boiler 1A, causing the generator to generate electricity. The steam supplied to the steam turbine 21 is discharged to a condenser 22. The condenser 22 cools and condenses the steam discharged from the steam turbine 21, turning it back into water. A condensate tank 23 stores the water returned from the steam by the condenser 22. A deaerator 24 removes oxygen from the water stored in the condensate tank 23. The water from which oxygen has been removed by the deaerator 24 is supplied to the economizer 1B. The economizer 1B heats the water supplied from the deaerator 24 with exhaust gas circulating from the boiler 1A. The water heated by the economizer 1B is circulated to the boiler 1A.

[0019] The exhaust gas that has passed through the economizer 1B passes through an upstream flue A connected to the economizer 1B and flows into the exhaust gas treatment device 100. The exhaust gas treatment device 100 has a dust removal device 3, an alkaline agent supply device 4, a blowing device 5, a downstream flue B1, a heat exchanger 7, a duct C, and a fly ash treatment facility 9.

[0020] 2 is a cross-sectional view of the position where the blowing device 5 is disposed in the upstream flue A. The blowing device 5 is disposed inside the upstream flue A, and is connected to the alkaline agent supplying device 4 and a duct C. The blowing device 5 also includes a vibrator 61 and a rod 62. The alkaline agent supplying device 4 is a device that supplies an alkaline agent to the blowing device 5 by air. The alkaline agent supplied by the alkaline agent supplying device 4 is, for example, hydrated lime. The duct C is a duct through which water vapor generated in the heat exchanger 7 described below flows, and is connected to the heat exchanger 7.

[0021] FIG. 3 is a schematic cross-sectional view of the blow-out device 5. The blow-out device 5 blows the alkaline agent, which is supplied together with air from the alkaline agent supply device 4, into the exhaust gas in the upstream flue A, and also blows water vapor that has flowed through the duct C into the exhaust gas in the upstream flue A. In the present invention, the blow-out device 5 constantly blows out the alkaline agent and water vapor, but they may do so intermittently. Alternatively, the concentrations of hydrogen chloride and sulfur dioxide in the upstream flue A may be measured, and the alkaline agent and water vapor may be blown out from the blow-out device 5 when a predetermined concentration abnormality is detected.

[0022] The blowing device 5 is composed of a first pipe 51, a second pipe 52, and a nozzle 53. The first pipe 51 and the second pipe 52 are metal pipes, and the first pipe 51 is arranged coaxially inside the second pipe 52. The first pipe 51 does not have to be coaxial with the second pipe 52, and the central axis of the first pipe 51 may be offset from that of the second pipe 52. It is preferable that the portion of the first pipe 51 located inside the second pipe 52 is a straight pipe with no change in diameter. The alkaline agent and air supplied from the alkaline agent supply device 4 pass between the outer peripheral surface of the first pipe 51 and the inner peripheral surface of the second pipe 52 and are blown out into the upstream flue A.

[0023] Also, the water vapor supplied from duct C flows through the first pipe 51 to the nozzle 53. The nozzle 53 is connected to the first pipe 51 and is composed of an enlarged portion 54 and a reduced portion 55. The nozzle 53 is located outside the second pipe 52 on the downstream side of the water vapor flow. The enlarged portion 54 has the shape of a hollow truncated cone, and its inner diameter and outer diameter increase as it goes toward the downstream side of the water vapor flow. The reduced portion 55 is integral with the enlarged portion 54, has a hemispherical outer surface and is hollow, and a blowout port 56 penetrating from the outer surface to the inner surface is formed on the downstream side of the water vapor flow. The reduced portion 55 has a smaller cross-sectional area perpendicular to the water vapor flow as it goes toward the tip where the blowout port 56 is provided. The blowout port 56 is an example of the opening according to the present invention.

[0024] Also, the water vapor supplied from duct C passes through the inside of the first pipe 51 and the nozzle 53 and is blown out from the blowout port 56 into the upstream flue A. The diameter of the first pipe 51 is, for example, 30 mm to 40 mm. Also, the diameter of the blowout port 56 is, for example, in the range of several mm to several tens of mm, and it is preferably smaller than the inner diameter of the first pipe 51.

[0025] When the radius of the outer peripheral surface of the reduced portion 55, which is hemispherical, is R, if R is small, the surface area of the nozzle 53 becomes narrow, so the flow of the alkaline agent and the flow of the water vapor become close, and the alkaline agent is likely to adhere to the nozzle 53. On the other hand, if R is large, the flow of the alkaline agent and the flow of the water vapor become far apart, the moisture contacting the alkaline agent decreases, and the effect of promoting the reaction of the alkaline agent by moisture cannot be sufficiently obtained. Therefore, in order to suppress the adhesion of the alkaline agent and obtain the effect of promoting the reaction of the alkaline agent by moisture, when the diameter of the first pipe 51 is D1, the diameter of the inner peripheral surface of the second pipe 52 is D2, and the radius of the outer peripheral surface of the reduced portion 55 is R, it is preferable that the relationship between D1 and R is 0.6×D1 < R < 1.5×D1, and it is more preferable that 0.7×D1 < R < 1×D1 and R < 0.35×D2.

[0026] The vibrator 61 is a device that vibrates the rod 62. The vibrator 61 is driven, for example, at a predetermined cycle. The rod 62 is a metal rod, and is vibrated by the vibrator 61. When vibrated by the vibrator 61, the rod 62 strikes the outer circumferential surface of the second pipe 52, and peels off the alkaline agent adhered to the second pipe 52 from the second pipe 52.

[0027] Returning to FIG. 1 , the dust remover 3 is configured, for example, with a bag filter, and receives humidified flue gas, which has been supplied with an alkaline agent and water vapor and has flowed through the upstream flue A. The dust remover 3 collects fly ash in the humidified flue gas that has entered, thereby removing dust from the humidified flue gas. At this time, the dust remover 3 also captures the alkaline agent along with the fly ash in the humidified flue gas. The fly ash collected in the dust remover 3 is supplied to a fly ash treatment facility 9. The humidified flue gas from which dust has been removed flows into the downstream flue B1 connected to the dust remover 3.

[0028] The fly ash treatment equipment 9 receives a stabilizer supplied from the outside and mixes (kneads) the stabilizer with the fly ash supplied from the dust removal device 3 to fix and stabilize (stabilize) the heavy metals contained in the fly ash, thereby reducing the amount of heavy metals leaching to below the standard value.

[0029] A heat exchanger 7 is connected to the downstream flue B1. The heat exchanger 7 is a device that generates water vapor by heating water supplied from the outside with humidified exhaust gas supplied from the downstream flue B1. The humidified exhaust gas that has passed through the heat exchanger 7 flows through the downstream flue B2 connected to the heat exchanger 7, undergoes appropriate detoxification treatment, and is released into the atmosphere from the chimney 2. The water vapor generated in the heat exchanger 7 flows to the blowing device 5 through the connected duct C. Note that the water vapor that flows to the blowing device 5 is not limited to the water vapor generated in the heat exchanger 7; for example, water vapor generated in the boiler 1A may also be flowed to the blowing device 5.

[0030] Furthermore, the water vapor supplied from the heat exchanger 7 is preferably at a temperature that brings the surface of the first pipe 51 to a temperature exceeding 100°C. FIGS. 4A and 4B are schematic cross-sectional views of the first pipe 51. The alkaline agent adheres to the surfaces of the first pipe 51 and the nozzle 53. Specifically, a first layer 201 to which the alkaline agent adheres is formed on the surfaces of the first pipe 51 and the nozzle 53. When the surface temperature of the first layer 201 is 100°C or lower, the water vapor blown out from the outlet 56 condenses on the surface of the first layer 201, and a second layer 202, which is permeated with moisture, is formed on the surface of the first layer 201. Here, the alkaline agent supplied from the second pipe 52 adheres to the second layer 202, and the alkaline agent is gradually piled up on the surface of the second layer 202. Furthermore, as the alkaline agent overlaps and the thickness of the first layer 201 increases, the heat transfer coefficient of the first layer 201 decreases and the temperature of the surface of the first layer 201 drops, causing the water vapor blown out from the outlet 56 to condense, further growing the first layer 201. In this way, the layer of alkaline agent initially formed on the surface of the contracting section 55 spreads and grows in sequence toward the expanding section 54 and the first pipe 51 in the upstream direction of the alkaline agent blowout.

[0031] On the other hand, when the surface temperature of first layer 201 exceeds 100°C, the moisture in the water vapor does not condense on the surface of first layer 201 and remains dry, preventing the formation of second layer 202 and suppressing the growth of first layer 201. When first layer 201 is dry, the flow of exhaust gas causes first layer 201 to peel off as shown in FIG. 4B , thereby suppressing the adhesion of the alkaline agent to the surfaces of first pipe 51 and nozzle 53.

[0032] FIG. 5 is a graph showing the relationship between the thickness of the first layer 201 and the surface temperature of the first layer 201. The solid line in FIG. 5 shows the relationship between the thickness of the first layer 201 and the surface temperature of the first layer 201 when the temperature of the steam in the first pipe 51 is 130°C, while the dashed line in FIG. 5 shows the relationship between the thickness of the first layer 201 and the surface temperature of the first layer 201 when the temperature of the steam in the first pipe 51 is 110°C. As shown in FIG. 5, when the temperature of the steam in the first pipe 51 is 130°C, the surface temperature of the first layer 201 exceeds 100°C even when the first layer 201 is thicker than when the temperature of the steam in the first pipe 51 is 110°C. This dries the surface of the first layer 201 and suppresses adhesion of the alkaline agent. Therefore, it is preferable that the temperature of the steam in the first pipe 51 be 130°C or higher. The desirable temperature of the water vapor may vary depending on the temperature of the air containing the alkaline agent, the flow rate of the air containing the alkaline agent, the material and thickness of the first pipe 51, and the like.

[0033] Although some of the water vapor injected into the exhaust gas from the nozzle 53 condenses, it preferentially condenses on the surface of the alkaline agent, which is energetically stable, and forms a water film on the surface of the alkaline agent injected from the second pipe 52 without condensing. By forming a water film on the surface of the alkaline agent in this way, acid gases are quickly absorbed into the water film, resulting in increased reactivity with the alkaline agent. Furthermore, the increased reactivity of the alkaline agent allows the alkaline agent to efficiently bind to pollutants such as hydrogen chloride and sulfur oxides contained in the exhaust gas, making it possible to reduce the amount of alkaline agent supplied from the alkaline agent supply device 4.

[0034] In this embodiment, the cross-sectional area of ​​the contracting section 55, perpendicular to the central axis of the nozzle 53, decreases toward the downstream side of the steam flow. This increases the temperature of the steam in the contracting section 55, drying the alkaline agent adhering to the surface of the nozzle 53 and preventing the alkaline agent from adhering to the nozzle 53. In this embodiment, the alkaline agent flows along the surface of the expanding section 54, which widens toward the downstream side of the flow. This increases the distance between the outlet 56 and the flow of alkaline agent, preventing the alkaline agent from adhering to the vicinity of the outlet 56. In this embodiment, the first pipe 51 is a straight pipe, and the outer circumferential surface of the first pipe 51 is parallel to the flow of the alkaline agent. Therefore, the alkaline agent moves in a straight line inside the second pipe 52. If the outer circumferential surface of the first pipe 51 were uneven, the alkaline agent would not move in a straight line, which would cause the alkaline agent to easily adhere to the opening of the second pipe 52. However, in this embodiment, the alkaline agent moves in a straight line inside the second pipe 52, preventing the alkaline agent from adhering to the opening of the second pipe 52. In addition, in this embodiment, the rod 62 is vibrated by the vibrator 61, and the vibrated rod 62 strikes the outer surface of the second pipe 52, so that the alkaline agent adhered near the opening of the second pipe 52 can be peeled off from the second pipe 52.

[0035] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be implemented in various other forms. For example, the above-described embodiments may be modified as follows to implement the present invention. The above-described embodiments and the following modifications may be combined with each other. The present invention also includes configurations in which the components of the above-described embodiments and modifications are appropriately combined. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments and modifications, and various modifications are possible.

[0036] In the above-described embodiment, when viewed from a direction perpendicular to the flow of water vapor, the position of the end of the first pipe 51 on the nozzle 53 side and the position of the end of the second pipe 52 on the nozzle 53 side are the same. However, in the present invention, as shown in FIG. 6, the end of the first pipe 51 on the nozzle 53 side may be configured to be located outside the second pipe 52 when viewed from a direction perpendicular to the flow of water vapor.

[0037] In the above-described embodiment, nozzle 53 for blowing out water vapor is composed of expanded portion 54 in the shape of a truncated cone and contracted portion 55 in the shape of a hemisphere, but the shape of the nozzle for blowing out water vapor is not limited to the shape in the embodiment and may be other shapes as shown in Figures 7A to 7D.

[0038] 7A is a cross-sectional view of a nozzle 53A according to a modified example. Nozzle 53A has a hollow tubular pipe portion 57a ​​between enlarged portion 54 and reduced portion 55. The diameter of the outer circumferential surface of pipe portion 57a ​​is larger than the diameter of the outer circumferential surface of first piping 51.

[0039] 7B is a cross-sectional view of nozzle 53B according to a modified example. Nozzle 53B does not include enlarged portion 54, and includes contracted portion 55b instead of contracted portion 55. Contracted portion 55b has a hollow hemispherical shape connected to first piping 51, and the diameter of the hemispherical shape is the same as the diameter of first piping 51. Contracted portion 55b has an outlet 56 formed at its tip, which penetrates through contracted portion 55b.

[0040] 7C is a cross-sectional view of a nozzle 53C according to a modified example. Nozzle 53C has a hollow, tubular pipe portion 57c. The outer diameter of pipe portion 57c is larger than the outer diameter of first pipe 51. In pipe portion 57c, blow-out port 56 penetrating pipe portion 57c is formed at a position on an extension of the central axis of first pipe 51.

[0041] 7D is a cross-sectional view of nozzle 53D according to a modified example. Nozzle 53D has expanded portion 54 in the shape of a hollow truncated cone and contracted portion 55d also in the shape of a hollow truncated cone. The outer periphery of contracted portion 55d in a cross section perpendicular to the flow of water vapor becomes smaller toward the downstream side of the flow of water vapor, and outlet 56 penetrating from the outer surface to the inner surface is formed downstream of the flow of water vapor. [Explanation of symbols]

[0042] 1. Waste incinerator 1A Boiler 1B Economizer 2. Chimney 3 Dust removal equipment 4. Alkaline agent supply device 5 Blowout device 7 Heat exchanger 9 Fly ash processing equipment 21 Steam turbine 22 Condenser 23 Condensate Tank 24 Deaerator 51 First Pipe 52 Second piping 53 nozzle 100 Exhaust gas treatment device 1000 Waste Incineration System A Upstream flue B1, B2 downstream flue C Duct

Claims

1. A blowing device provided in a flue through which exhaust gas discharged from a waste incinerator flows, a first pipe through which water vapor flows; a second pipe in which the first pipe is disposed; a nozzle connected to the first pipe; and air containing an alkaline agent flows between the inner surface of the second pipe and the outer surface of the first pipe; The nozzle has a converging portion whose cross-sectional area decreases toward the tip, The reducing section has an opening for blowing the water vapor into the exhaust gas discharged from the waste incinerator. Blowing device.

2. The nozzle has an expanding portion whose cross-sectional area expands toward the tip, The contracted portion is provided on the distal end side of the expanded portion. The blowing device according to claim 1 .

3. The outer surface of the reduced portion is hemispherical. The blowing device according to claim 2 .

4. The water vapor is at least 130°C at the nozzle. The blowing device according to claim 1 .

5. a rod in contact with the second pipe; and a vibrator that vibrates the rod; The blowing device according to claim 1 , comprising:

6. The diameter of the opening of the nozzle through which the steam is blown out is smaller than the inner diameter of the first pipe. The blowing device according to claim 1 .

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