Exhaust gas sampler

Abstract

To provide an exhaust gas sampler capable of removing dust from an exhaust gas and introducing the exhaust gas to a mercury concentration detector while capable of removing the dust attached to filter cloth with a simple configuration.SOLUTION: An exhaust gas sampler 6 includes: a housing 61 having a cylindrical portion 61a, a lid portion 61b and an opening portion 61c, for sucking part of an exhaust gas containing dust passing through a gas flue 2 and introducing into a mercury concentration detector 7, with the opening portion 61c arranged at the gas flue 2; filter cloth 62 attached to the housing 61 so as to cover the opening portion 61c; an exhaust gas introduction pipe 65 penetrating through the lid portion 61a with a tip thereof arranged to reach an interior space 61S surrounded by the housing 61 and the filter cloth 62, and configured to suck from the tip the exhaust gas having passed through the filter cloth 62 and flowing into the interior space 61S to introduce into the mercury concentration detector 7; and a cleaning gas supply pipe 66 penetrating through the lid portion 61b with a tip thereof arranged in the interior space 61S and configured to jet a cleaning gas from the tip toward the filter cloth 62.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a flue gas collector for collecting flue gas passing through a flue. [Background technology]

[0002] For example, in a combustion furnace such as a refuse incinerator, the exhaust gas generated when waste is burned may contain mercury. The exhaust gas generated in the combustion furnace is sent to a flue, where dust is removed by a filter-type dust collector installed along the flue, and then released into the atmosphere through a chimney. From the perspective of preventing air pollution caused by this released exhaust gas, it is necessary to monitor the mercury concentration in the exhaust gas passing through the flue and take action when the mercury concentration increases. Here, in order to monitor the mercury concentration in the exhaust gas in the filter-type dust collector inlet flue, it is necessary to sample the dust-containing exhaust gas. The structure of a probe for sampling such exhaust gas is described, for example, in Patent Document 1.

[0003] Patent Document 1 describes a configuration in which a cylindrical filter is placed inside a cylindrical case and a cylindrical multi-hole nozzle is placed inside the filter. The multi-hole nozzle has many holes formed on the cylindrical side surface. With this configuration, when performing gas analysis, a sampling gas introduced into the cylindrical case is passed through the filter to remove dust without introducing a purge gas, and the gas is then led to a gas analyzer. Furthermore, when removing dust adhering to the filter, a purge gas consisting of nitrogen gas or air is sent into the multi-hole nozzle, and the purge gas is ejected from the many holes in the multi-hole nozzle to remove the dust adhering to the filter. At this time, the piping leading to the gas analyzer is closed to prevent the purge gas from flowing into the gas analyzer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-274606 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, a cylindrical multi-hole nozzle is disposed inside a cylindrical filter, and the multi-hole nozzle has many holes formed on the cylindrical side surface, which makes the probe structure complex.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an exhaust gas sampler with a simple structure that can remove dust from exhaust gas and introduce it into a mercury concentration detector, as well as remove dust adhering to the filter cloth. [Means for solving the problem]

[0007] In order to achieve the above object, an exhaust gas sampler according to one aspect of the present disclosure is a flue gas sampler for sucking in a portion of dust-containing exhaust gas passing through a flue and introducing it into a mercury concentration detector that detects the mercury concentration in the exhaust gas, and is equipped with: a housing having a cylindrical portion, a lid portion that closes one end of the cylindrical portion, and an opening portion that is open at the other end of the cylindrical portion, the opening portion being arranged in the flue; a filter cloth attached to the housing so as to cover the opening portion of the housing; an exhaust gas inlet pipe that penetrates the lid portion of the housing and is arranged so that its tip reaches an internal space surrounded by the housing and the filter cloth, and is used to suck in, from the tip, exhaust gas that passes through the filter cloth and flows into the internal space, and introduce it into the mercury concentration detector; and a cleaning gas supply pipe that penetrates the lid portion of the housing and has its tip positioned in the internal space, and is used to spray cleaning gas from the tip toward the filter cloth that covers the opening portion of the housing. [Effects of the Invention]

[0008] The present disclosure has the above-described configuration and has the effect of providing an exhaust gas collector with a simple structure that can remove dust from exhaust gas and introduce it into a mercury concentration detector, as well as remove dust adhering to a filter cloth. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an example of an incineration plant equipped with a flue gas collector according to this embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of the exhaust gas collector of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described below with reference to the drawings. Note that the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant explanations will be omitted. The drawings are schematic illustrations of the respective components for ease of understanding, and the shapes, dimensional ratios, and the like may not be accurately depicted. The present disclosure is not limited to the following embodiments.

[0011] (Embodiment) Fig. 1 is a diagram showing the schematic configuration of an example of an incineration plant equipped with a flue gas collector of this embodiment. The incineration plant AS shown in Fig. 1 includes a combustion furnace 1, a flue 2, a filter-type dust collector 3, a blower 4, a chimney 5, a flue gas collector 6, a mercury concentration detector 7, a cleaning gas supply device 8, an activated carbon supply device 9, and a controller 10.

[0012] The combustion furnace 1 is a device for incinerating waste and has an exhaust gas outlet 11 for discharging exhaust gas and an ash outlet 12. The combustion furnace 1 may be an incinerator equipped with a waste heat boiler or the like. The flue 2 is the flow path for exhaust gas from the exhaust gas outlet 11 of the combustion furnace 1 to the chimney 5. A filter-type dust collector 3 and a blower 4 are installed in the middle of the flue 2. The exhaust gas discharged from the combustion furnace 1 travels through the flue 2 in the direction of arrow a, is purified by the filter-type dust collector 3, and is then released into the atmosphere from the chimney 5 via the blower 4.

[0013] The flue gas sampler 6 sucks in a portion of the dust-containing flue gas passing through the flue 2 between the flue gas outlet 11 of the combustion furnace 1 and the filter-type dust collector 3, and sends it to the mercury concentration detector 7 via the flue gas inlet pipe 65. Details of this flue gas sampler 6 will be described later.

[0014] Mercury concentration detector 7 continuously detects the mercury concentration in the flue gas introduced from flue gas sampler 6 through flue gas introduction pipe 65 and transmits the detected mercury concentration to controller 10. Mercury concentration detector 7 is a device that reduces mercury compounds in the flue gas with a solid reducing agent, and measures the absorbance of gaseous mercury based on atomic absorption spectrometry to calculate the mercury concentration.

[0015] The cleaning gas supply device 8 periodically instantaneously sends cleaning gas to the exhaust gas collector 6 via the cleaning gas supply pipe 66. In this example, compressed air is used as the cleaning gas.

[0016] The activated carbon supply device 9 supplies activated carbon to the flue 2 between the flue gas collector 6 and the filter-type dust collector 3.

[0017] The controller 10 is a computer having an arithmetic unit such as a CPU and storage units such as a ROM and a RAM, and the CPU executes a predetermined program pre-stored in the storage unit to control the cleaning gas supply device 8 and the activated carbon supply device 9. The controller 10 also receives the mercury concentration detected by the mercury concentration detector 7. The controller 10 may be configured as a single controller for centralized control, or may be configured as a plurality of controllers for decentralized control in cooperation with each other.

[0018] 2 is a schematic cross-sectional view showing an example of the exhaust gas collector 6. The exhaust gas collector 6 includes a housing 61, a filter cloth 62, a filter cloth fixture 64, an exhaust gas introduction pipe 65, and a cleaning gas supply pipe 66.

[0019] The housing 61 has a cylindrical portion 61a, a lid portion 61b that closes one end of the cylindrical portion 61a, and an opening portion 61c that is open at the other end of the cylindrical portion 61a, with the opening portion 61c being disposed within the flue 2. The cylindrical portion 61a has a first cylindrical portion 611, a second cylindrical portion 613 that has a smaller diameter than the first cylindrical portion 611, and a reducer portion 612 that connects the first cylindrical portion 611 and the second cylindrical portion 613. Note that the cylindrical portion 61a may be configured as a single cylinder. The lid portion 61b is disc-shaped and has a diameter larger than that of the cylindrical portion 61a, and the peripheral portion of the lid portion 61b that protrudes from the cylindrical portion 61a is fixed to the annular mounting portion 23 of the flue gas collector mounting fixture 20 with a plurality of bolts BT, with a gasket P sandwiched between them.

[0020] The flue gas collector mounting fixture 20 has a cylindrical portion 21, a fixed portion 22 fixed to one end of the cylindrical portion 21, and an annular mounting portion 23 fixed to the other end of the cylindrical portion 21. A hole 2a for disposing the flue gas collector 6 is opened in a duct 2D that constitutes the flue 2. The fixed portion 22 extends outward from the periphery of one end of the cylindrical portion 21 and is fixed to the outer portion of the duct 2D around the hole 2a so as to be in close contact with the duct 2D.

[0021] In the exhaust gas collector 6, the filter cloth 62 is attached to the housing 61 so as to cover the opening 61c of the housing 61. The filter cloth 62 has the shape of a cylindrical bag with a bottom, having a circular bottom portion 62a and a cylindrical side portion 62b. The bottom portion 62a of the bag covers the opening 61c of the housing 61, and the inner surface of the side portion 62b of the bag is aligned with the outer surface of the second cylindrical portion 613 of the cylindrical portion 61a of the housing 61. The side portion 62b of the bag is fixed to the second cylindrical portion 613 using a filter cloth fixture 64, thereby attaching the filter cloth 62 to the housing 61. A fastening metal fitting such as a hose band can be used as the filter cloth fixture 64. Attaching the bag-shaped filter cloth 62 to the housing 61 in this manner allows the filter cloth 62 to be firmly attached to the housing 61, preventing the filter cloth 62 from coming off the housing 61 due to the injection of cleaning gas. A ring-shaped protrusion 63 is formed at the tip of the second cylindrical portion 613 of the tubular portion 61a, which further prevents the filter cloth 62 from coming off the housing 61.

[0022] The exhaust gas inlet pipe 65 penetrates the lid portion 61b of the housing 61 and is disposed so that its tip reaches the internal space 61S of the housing 61, and its base end is drawn into the mercury concentration detector 7. The exhaust gas inlet pipe 65 sucks, from its tip, exhaust gas that passes through the filter cloth 62 and flows into the internal space 61S of the housing 61 and introduces it into the mercury concentration detector 7. A suction pump is installed inside the mercury concentration detector 7, and this suction pump sucks the exhaust gas in the internal space 61S of the housing 61 into the exhaust gas inlet pipe 65. The internal space 61S of the housing 61 is the internal space surrounded by the housing 61 and the filter cloth 62. If exhaust gas containing dust were introduced into the mercury concentration detector 7, malfunctions would occur within the mercury concentration detector 7. Therefore, the exhaust gas from which the dust has been removed by the filter cloth 62 is introduced into the mercury concentration detector 7 through the exhaust gas inlet pipe 65. Therefore, the filter cloth 62 has the function of allowing gas to pass through but not allowing dust in the exhaust gas to pass through.

[0023] The cleaning gas supply pipe 66 penetrates the lid portion 61b of the housing 61, with its tip disposed in the internal space 61S of the housing 61 and its base end connected to the cleaning gas supply device 8. The cleaning gas supply pipe 66 is arranged so that the cleaning gas supplied from the cleaning gas supply device 8 is sprayed from the tip of the cleaning gas supply pipe 66 toward the filter cloth 62. Here, as in this example, it is preferable that the tip of the cleaning gas supply pipe 66 is arranged at a position closer to the filter cloth 62 than the tip of the exhaust gas introduction pipe 65. It is also preferable that the cleaning gas supply pipe 66 is arranged so that the center line CL of the tip portion of the cleaning gas supply pipe 66 passes through the center of the opening portion 61c of the housing 61.

[0024] In this example, the housing 61 is arranged so that the opening 61c is located inside the inner surface of the duct 2D that constitutes the flue 2, making it easy to take in the exhaust gas passing through the flue 2 into the housing 61, but this is not limiting. For example, the housing 61 may be arranged so that the opening 61c is located at the same level as the inner surface of the duct 2D, or may be arranged so that it is located outside the inner surface of the duct 2D.

[0025] In this embodiment, during operation of the incineration plant AS, the controller 10 constantly operates the mercury concentration detector 7 and periodically activates the cleaning gas supply device 8. That is, without stopping the suction pump in the mercury concentration detector 7, cleaning gas is periodically instantaneously injected from the tip of the cleaning gas supply pipe 66 toward the filter cloth 62 in the flue gas collector 6 while flue gas is being sucked into the flue gas inlet pipe 65. As a result, when cleaning gas is not being injected, dust in the flue gas adheres to the filter cloth 62 when flue gas is sucked from the tip of the flue gas inlet pipe 65, and the dust-removed flue gas can be introduced into the mercury concentration detector 7. Furthermore, when cleaning gas is injected from the tip of the cleaning gas supply pipe 66, the dust adhering to the filter cloth 62 is blown away by the cleaning gas, thereby removing the dust from the filter cloth 62. The exhaust gas collector 6 does not have a complex structure in which a cylindrical multi-hole nozzle is placed inside a cylindrical filter as in Patent Document 1, but can have a simple structure in which a filter cloth 62 is attached to a cylindrical housing 61 so as to cover an opening portion 61c of the housing 61.

[0026] Furthermore, the tip of the cleaning gas supply pipe 66 is positioned closer to the filter cloth 62 than the tip of the exhaust gas introduction pipe 65, and the cleaning gas supply pipe 66 is positioned so that the center line CL of the tip of the cleaning gas supply pipe 66 passes through the center of the opening 61c of the casing 61. This allows the cleaning gas to be accurately sprayed toward the filter cloth 62 covering the opening 61c of the casing 61, and dust adhering to the filter cloth 62 can be more effectively removed.

[0027] In this embodiment, the mercury concentration detector 7 continuously transmits the detected mercury concentration to the controller 10. The controller 10 compares the mercury concentration received from the mercury concentration detector 7 with a predetermined reference concentration, and if the mercury concentration received from the mercury concentration detector 7 exceeds the predetermined reference concentration, the controller 10 transmits an activated carbon increase command to the activated carbon supply device 9, which is a command to increase the amount of activated carbon supplied. Until the activated carbon increase command is received, the activated carbon supply device 9 sprays and supplies a predetermined reference amount of activated carbon into the flue 2. This causes dioxins contained in the flue gas to be adsorbed onto the activated carbon. Then, upon receiving the activated carbon increase command, the activated carbon supply device 9 increases the amount of activated carbon supplied into the flue 2 by a predetermined amount. This causes mercury, along with dioxins contained in the flue gas, to be adsorbed onto the activated carbon. In this way, the dioxins and mercury adsorbed onto the activated carbon are removed from the flue gas together with the activated carbon by the filter-type dust collector 3.

[0028] Furthermore, the controller 10 compares the mercury concentration received from the mercury concentration detector 7 with a predetermined reference concentration, and when the mercury concentration received from the mercury concentration detector 7 falls below the predetermined reference concentration, it transmits an activated carbon reduction command to the activated carbon supply device 9 to reduce the amount of activated carbon supplied. Upon receiving the activated carbon reduction command, the activated carbon supply device 9 returns the amount of activated carbon supplied to the predetermined reference amount.

[0029] In this embodiment, the flue gas collector 6 and the mercury concentration detector 7 constitute a first mercury concentration detection device that detects the mercury concentration of the flue gas in the flue 2 upstream of the filtering dust collector 3. This embodiment may further include a second mercury concentration detection device that detects the mercury concentration of the flue gas in the flue 2 downstream of the filtering dust collector 3. The controller 10 may be configured to increase or decrease the amount of activated carbon supplied by the activated carbon supply device 9 based on an increase or decrease in the mercury concentration detected by the first mercury concentration detection device and the second mercury concentration detection device.

[0030] Further, a cooling tower for lowering the temperature of the exhaust gas may be installed in the flue 2 between the exhaust gas outlet 11 of the combustion furnace 1 and the exhaust gas collector 6.

[0031] From the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof can be substantially changed without departing from the spirit of the present disclosure.

[0032] Summary of the Disclosure a housing having a cylindrical portion, a lid portion closing one end of the cylindrical portion, and an opening portion open at the other end of the cylindrical portion, the opening portion being arranged in the flue; a filter cloth attached to the housing so as to cover the opening portion of the housing; an exhaust gas inlet pipe that penetrates the lid portion of the housing and has a tip that reaches an internal space surrounded by the housing and the filter cloth, and that sucks in, from the tip, the exhaust gas that passes through the filter cloth and flows into the internal space, and introduces it into the mercury concentration detector; and a cleaning gas supply pipe that penetrates the lid portion of the housing and has a tip that is arranged in the internal space, and that sprays a cleaning gas from the tip toward the filter cloth that covers the opening portion of the housing.

[0033] According to this configuration, when cleaning gas is not being injected, dust in the flue gas adheres to the filter cloth when the flue gas is sucked from the tip of the flue gas inlet pipe, and the dust-removed flue gas can be introduced into the mercury concentration detector. Furthermore, when cleaning gas is injected from the tip of the cleaning gas supply pipe, the dust adhering to the filter cloth is blown away by the cleaning gas, allowing the dust adhering to the filter cloth to be removed. This flue gas sampler does not have a complex structure such as that of Patent Document 1, in which a cylindrical multi-hole nozzle is disposed inside a cylindrical filter, but can have a simple structure in which the filter cloth is attached to a cylindrical housing so as to cover the opening of the housing.

[0034] The exhaust gas sampler according to the second aspect may be the exhaust gas sampler according to the first aspect, wherein the tip of the cleaning gas supply pipe is positioned closer to the filter cloth than the tip of the exhaust gas inlet pipe, and the cleaning gas supply pipe is positioned so that the center line of the tip of the cleaning gas supply pipe passes through the center of the opening of the housing.

[0035] According to this configuration, the cleaning gas can be accurately sprayed toward the filter cloth covering the opening of the housing, and dust adhering to the filter cloth can be more effectively removed.

[0036] The exhaust gas collector of the third aspect may be the exhaust gas collector of the first or second aspect, wherein the filter cloth has the shape of a cylindrical bag with a bottom, and the bottom portion of the bag covers the opening of the housing, and the inner surface of the side portion of the bag is aligned with the outer surface of the cylindrical portion of the housing, and the filter cloth is attached to the housing by fixing the side portion of the bag to the cylindrical portion of the housing.

[0037] According to this configuration, the filter cloth can be firmly attached to the housing, and the filter cloth can be prevented from coming off the housing due to the injection of cleaning gas.

[0038] A fourth aspect of the flue gas extractor is the flue gas extractor of any one of the first to third aspects, wherein the housing is arranged so that the opening is located inside the inner surface of a duct that constitutes the flue, making it easier to take in flue gas passing through the flue into the housing. [Explanation of symbols]

[0039] 2 flue 6. Exhaust gas sampler 7. Mercury concentration detector 61 Case 61a Cylindrical part of the housing 61b Lid of the housing 61c Housing opening 61S interior space 62 Filter cloth 65 Exhaust gas introduction pipe 66 Cleaning gas supply pipe

Claims

1. A flue gas sampler for sucking in a portion of dust-containing flue gas passing through a flue and introducing the gas into a mercury concentration detector for detecting a mercury concentration in the flue gas, a housing having a cylindrical portion, a lid portion closing one end of the cylindrical portion, and an opening portion that is open at the other end of the cylindrical portion, the opening portion being disposed in the flue; a filter cloth attached to the housing so as to cover the opening of the housing; an exhaust gas introduction pipe that penetrates the lid of the housing and has a tip that reaches an internal space surrounded by the housing and the filter cloth, and that sucks in exhaust gas that passes through the filter cloth and flows into the internal space from the tip and introduces the exhaust gas into the mercury concentration detector; a cleaning gas supply pipe that penetrates the lid portion of the housing, has a tip that is disposed in the internal space, and that injects cleaning gas from the tip toward the filter cloth that covers the opening portion of the housing; A flue gas collector comprising:

2. a tip of the cleaning gas supply pipe is disposed at a position closer to the filter cloth than a tip of the exhaust gas introduction pipe, and the cleaning gas supply pipe is disposed so that a center line of the tip portion of the cleaning gas supply pipe passes through a center of the opening portion of the housing.

2. The exhaust gas collector of claim 1.

3. The filter cloth has a shape of a cylindrical bag with a bottom, and the bottom surface of the bag covers the opening of the housing, and the inner surface of the side surface of the bag is aligned with the outer surface of the cylindrical portion of the housing, and the side surface of the bag is fixed to the cylindrical portion of the housing, thereby attaching the filter cloth to the housing.

3. A flue gas collector according to claim 1 or 2.

4. The housing is arranged so that the opening portion is located inside the inner surface of a duct that constitutes the flue.

3. A flue gas collector according to claim 1 or 2.

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