JP2008264662A - Method and apparatus for treating exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for treating an exhaust gas which can reduce attachment of a chemical agent to the inside of a crusher or a fan by introducing the gas after collecting dust with a dust collecting means to a fluidizing-type crushing means so as to be circulated and by crushing the chemical agent by the fluidizing-type crushing means. <P>SOLUTION: In the method for treating the exhaust gas, a sodium-based chemical agent is used as the chemical agent to introduce the gas after collecting dust with a filtering-type dust collector 4 to the fluidizing-type crushing means 15 so as to be circulated, so that the chemical agent is crushed by the fluidizing-type crushing means 15 to introduce the crushed chemical agent to the upstream side of the dust collector 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment method and an exhaust gas treatment device, and more particularly, to an exhaust gas treatment method and an exhaust gas treatment device that perform a detoxification treatment of an acidic gas component in exhaust gas generated during incineration of garbage in a dry manner.

  Exhaust gas treatment facilities provided at garbage incineration facilities, etc. contain harmful components consisting of acidic gases such as HCl and SOx in the exhaust gas generated by incineration, so that these are removed and released to the atmosphere. I have to.

  As such an exhaust gas treatment facility, for example, as a dry method, exhaust gas discharged from an incinerator is introduced into a temperature-decreasing tower or a economizer, and supplied to a dust collector consisting of a bag filter or the like via a duct. Then, a chemical agent composed of a single substance or a mixture of two or more kinds is blown to neutralize and remove the acid gas component, and fly ash is removed and cleaned, and the air is released from the chimney to the atmosphere by an induction fan.

  As this exhaust gas treatment facility, the following configuration is adopted so that the above-mentioned chemical is introduced to the upstream side of the dust collector. As a first configuration shown in FIG. 5, a medicine storage tank 51 for storing medicine, a quantitative supply device 52 for supplying a fixed amount of medicine from the medicine storage tank 51, and this quantitative supply device 52 A pulverizer 53 for pulverizing the supplied medicine into a predetermined particle size range, and an induction blower 54 for conveying the medicine pulverized in the predetermined particle size range by the pulverizer 53 to the upstream side of the dust collector in the exhaust gas path. Have.

  The second configuration is a method of introducing a chemical for neutralizing an acidic gas component in exhaust gas into the exhaust gas and treating fly ash and / or reaction products in the exhaust gas with a dust collector. In addition, the drug is introduced into a bypass route provided on either or both of the upstream side and the downstream side of the dust collector, and the drug is pulverized immediately before the introduction (Patent Document 1). As this pulverizer, the chemicals are pulverized by blades of a pulverization rotor, particles having a predetermined particle size are classified by centrifugation with a classification rotor, and the classified coarse particles are subjected to pulverization again to particles having a predetermined particle size or less. Only a dispersive pulverizer is illustrated which is configured such that only the air flows from the pulverizer. Examples of the pulverizer include a mechanical high-speed rotary pin mill and a hammer-type pulverizer.

JP 2002-136840 A (Claim 1, paragraph number 0030)

  However, in the case of the above configurations 1 and 2, when a dispersive pulverizer, a mechanical high-speed rotary pin mill, or a hammer-type pulverizer is used as a pulverizer, a rotating body (such as a pulverization rotor or a classification rotor), a pin disk The chemicals adhered to the pulverizing hammer and the balance as a machine was lost, causing vibrations, resulting in significant damage to internal parts, occurrence of overload, and a decrease in pulverization efficiency. In such a case, it is necessary to perform cleaning in order to remove regularly adhered chemicals. However, if periodic cleaning is frequent, the work burden is large and the operating efficiency of the device is deteriorated. Was desired.

  Further, in the case of the above-described configuration 1, by providing the induction blower 54 for transporting the medicine, the inside of the grinder is brought into a negative pressure state, and the powder (finely ground medicine) enters the bearing portion of the grinder. Can be prevented. However, since the powder passes through the inside of the induction fan 54, the powder as a pulverized product adheres to the rotating body inside the induction fan 54. Due to the adhesion of the powder, the balance of the induced blower 54 is lost and vibration is generated, leading to the occurrence of overload. Even in such a case, it is necessary to perform cleaning in order to remove the regularly attached medicine, but if the periodic cleaning is frequent, the work burden is large, and the operation efficiency of the device is also deteriorated. There was a strong need for improvement.

  On the other hand, when the blowing means is provided on the upstream side of the pulverizing means as in the configuration 2, the above-described problem of the blower does not occur, but the problem that the powder enters the bearing portion of the pulverizer occurs. .

  In addition, when using a sodium-based drug, it is necessary to generate a highly active drug by making it sufficiently porous. Therefore, in order to generate pores (about several tens of nanometers) enough to adsorb exhaust gas components (acid gas, etc.) in a gas atmosphere at 140 ° C. or higher in the path from the powder blowing port of the exhaust gas path to the dust collector entrance. In addition, it is necessary to ensure a sufficient path length from the powder blowing port to the dust collector entrance in the exhaust gas path.

  However, in the above-described configuration 1, by securing this path length, the entire apparatus becomes large, which is not preferable in terms of installation area. In addition, in order to make the chemical gas atmosphere at 140 ° C. or higher before being introduced into the exhaust gas path, a sufficient path length is secured from the pulverizer outlet to the powder blowing port of the exhaust gas path, and hot air at 140 ° C. or higher. Although it is conceivable to separately provide a means for generating, it is not a preferable method from the viewpoint of equipment cost.

  Further, when the circulating gas is used as in Configuration 2, since the circulating gas is warm air, it is only necessary to secure a path length from the pulverizer outlet to the powder blowing port of the exhaust gas path. If it is long, it is not preferable from the viewpoint of the installation area of the apparatus by the amount of securing the path length.

  In the case of the above configuration 1, since the atmosphere is sucked from the outside and used as drug transport air, the drug transport air is blown into the exhaust gas path, so the amount of exhaust gas discharged from the chimney increases. There is a problem of end.

  Therefore, the present invention has been made in view of the above-described problems of the prior art, and its purpose is to introduce the gas after dust collection by the dust collection means into the fluidized grinding means, An object of the present invention is to provide an exhaust gas treatment method and an exhaust gas treatment device that can reduce the adhesion of chemicals to the inside of a pulverizer or a blower by pulverizing the chemical using a fluid pulverization means.

The above-mentioned subject is achieved by the invention described in each claim. That is, in the exhaust gas treatment method, an agent for neutralizing the acidic gas component in the exhaust gas is introduced into the exhaust gas, and the exhaust ash and / or reaction product in the exhaust gas is treated by dust collecting means. Because
Using a sodium-based drug as the drug,
Providing a path for circulating the gas after dust collection by the dust collecting means;
Introducing the gas into the fluidized grinding means in the path,
Crushing the drug using the fluidized crushing means,
The pulverized medicine is introduced to the upstream side of the dust collecting means through the route.

  The effects of this configuration are as follows. That is, in the exhaust gas treatment method, a chemical for neutralizing the acidic gas component in the exhaust gas is introduced into the exhaust gas, and the fly ash and / or reaction product in the exhaust gas can be treated by the dust collecting means. . A circulation path (feedback) that circulates gas from the downstream side after dust collection by the dust collection means to the upstream side of the dust collection means is provided. Then, the pulverized medicine is blown to the upstream side of the dust collecting means. A push-in blower as a circulating gas blowing means is provided on the upstream side of the fluid pulverizer.

  According to the exhaust gas treatment method configured as described above, a special effect is achieved as compared with the following conventional technology. That is, since the fluidized pulverizing means is used as the pulverizing means, there is no problem due to the adhesion of the powder (medicine) inside the pulverizing means. By providing the air blowing means on the upstream side of the pulverizing means, the powder does not pass inside the air blowing means, so that there is no problem due to the powder adhering inside the air blowing means. Further, by using a circulating gas that is warm air (140 ° C. or higher) as the gas introduced into the fluidized pulverizing means, the path length from the powder blowing inlet to the dust collecting means inlet can be shortened. Since the volume of the fluidized bed (empty space) of the pulverizing means is set large, the path length from the outlet of the fluidized pulverizing means to the powder blowing inlet can be shortened. That is, when using a sodium-type chemical | medical agent, while being grind | pulverized by a fluid-type grinding | pulverization means, substantially the whole quantity is made porous inside the said fluidized bed. In addition, by using the circulating gas, it is possible to reduce the amount of exhaust gas discharged from the chimney compared to a method using outside air.

  Further, in the above exhaust gas treatment method, when the exhaust gas is not generated, hot air is generated in the circulation path so as to prevent deterioration of the function of the dust collecting means.

  According to this configuration, the hot air is introduced into the dust collecting means in order to prevent the function of the dust collecting means from deteriorating (for example, the function deteriorating due to the binding of the drug to the bag filter while the exhaust gas treatment is suspended). Composed. As a route for introducing the hot air, a circulation route from the exhaust gas route or a bag filter hot air circulation line can be applied. It is preferable to install the fluidized crushing means in the bag filter hot air circulation line because the fan of the bag filter hot air circulation line can be used, so that it is not necessary to separately install the fan.

  In addition, as an example of a preferred embodiment of the present invention described above, in the case of drug pulverization by fluid pulverization means, cinnabar sand and / or aluminum oxide is used as a fluid medium.

According to this configuration, in the case of chemical pulverization by the fluid pulverization means, cinnabar sand and / or aluminum oxide can be used as the fluid medium. The fluid medium is gradually pulverized by the fluid pulverization means and carries over with the sodium-based chemical agent, but exhibits the same action as the reaction aid, and is useful for improving the reactivity and improving the scraping property. Sodium-based chemicals have high reaction efficiency without any special reaction aids and good removal properties, but the presence of reaction aids suppresses the pressure loss of the adhering dust layer and improves the removal properties. Since a fluid medium can be used in place of this reaction aid, it is excellent in terms of economy and equipment without further use of a reaction aid. Mineral sand (also referred to as silica sand) is quartz sand that is rich in silicon dioxide (SiO ₂ ) components. As the particle size range of the cinnabar, for example, a range of 0.5 mm to 3 mm is preferable.

  As another example of the preferred embodiment of the present invention, in the case of chemical pulverization by fluid pulverization means, the superficial velocity of the fluid pulverization means is a value in the range of 0.15 to 0.2 m / s. It is characterized by being.

  According to this configuration, the chemical can be pulverized to a pulverized particle size of approximately 20 μm by controlling the superficial velocity of the fluidized pulverizing means to be in the range of 0.15 to 0.2 m / s, and flows along with the rising fluid gas. It can be transported to the path from the inside of the pulverizing means, and can be transported as it is just before the upstream side of the dust collecting means in the exhaust gas path. By setting the sodium-based drug to a particle size of about 20 μm, the reactivity is improved, and the porous layer is sufficiently made porous.

Further, as one embodiment of the exhaust gas treatment method of the present invention, a chemical for neutralizing acidic gas components in the exhaust gas is introduced into the exhaust gas, and fly ash and / or reaction production in the exhaust gas is collected by dust collecting means. An exhaust gas treatment apparatus for treating an object,
A path for circulating the gas after dust collection by the dust collecting means and introducing it to the upstream side of the dust collecting means, a push-in type blower for guiding the circulating gas into the path, and the path Fluid-type pulverizing means for pulverizing the medicine is provided on the rear side of the push-in type blower.

  According to this configuration, the exhaust gas treatment apparatus circulates the gas after dust collection by the dust collecting means and introduces it to the upstream side of the dust collecting means, and a push for guiding the circulating gas into the path. And a fluidized pulverizing means for pulverizing the medicine on the downstream side of the push-in type fan in the path. This effect is as described above.

  Further, as a preferred embodiment of the exhaust gas treatment apparatus, when the exhaust gas is not generated, the hot air generating means for generating hot air in the circulation path so as to prevent the function of the dust collecting means from being deteriorated. It further has these.

  According to this structure, when exhaust gas is not produced | generated, it is comprised so that a warm air can be produced | generated and it can ventilate to a dust collection means so that the function fall of a dust collection means may be prevented.

  Embodiments according to the present invention will be described in detail with reference to the drawings. 1 and 2 are diagrams for explaining an example of an exhaust gas treatment apparatus according to Embodiments 1 and 2, respectively.

(Embodiment 1)
The exhaust gas treatment method of Embodiment 1 uses a sodium-based chemical as a chemical, introduces the gas after dust collection by the dust collecting means into the fluidized grinding means, and pulverizes the chemical using the fluidized grinding means. The pulverized medicine is introduced upstream of the dust collecting means. And the exhaust gas treatment apparatus for realizing this method circulates the gas after dust collection by the dust collecting means and introduces the circulating gas into the path to be introduced upstream of the dust collecting means. And a fluid-type pulverizing means for pulverizing the drug on the downstream side of the push-type fan in the path.

(Drug)
Examples of the drug include sodium-based drugs such as sodium hydrogen carbonate (sodium bicarbonate) and sodium carbonate, and sodium hydrogen carbonate is particularly preferable. The average particle size of the pulverized drug (sodium bicarbonate) is preferably in the range of 10 μm to 50 μm, more preferably in the range of 15 μm to 30 μm, and particularly preferably in the range of 18 μm to 22 μm.

  The particle size of the drug can be measured by, for example, LDV (laser Doppler velocimeter).

(Exhaust gas treatment equipment)
The exhaust gas treatment apparatus is an exhaust gas treatment apparatus that introduces a chemical for neutralizing an acidic gas component in exhaust gas into the exhaust gas, and processes fly ash and / or reaction products in the exhaust gas by dust collection means. . In the following, known configurations will be briefly described, and configurations specific to the present invention will be described in detail. Moreover, it demonstrates as what uses sodium hydrogencarbonate for a chemical | medical agent.

  As shown in FIG. 1, the exhaust gas treatment apparatus includes a temperature reducing tower 3 (or a economizer), a filtration dust collector 4 (corresponding to dust collecting means), an induction fan 5, an exhaust gas path (pipe), and a circulating gas path. 11. A blower 12 (corresponding to a push-type blower) for sucking gas into a circulation gas path and introducing the gas into the downstream fluid pulverizer 15; a medicine storage tank 13 (medicine storage tank) for storing medicine Equivalent to the means), a fixed amount supply device 14 for supplying a fixed amount of drug from the drug storage tank 13, and a fluid type pulverization for pulverizing the drug supplied from the fixed amount supply device 14 in a predetermined particle size range. Machine 15 (corresponding to a fluid pulverizing means) and the like are mainly provided.

  As shown in FIG. 1, the exhaust gas discharged from the incinerator 1 is introduced into the temperature reducing tower 3 through the waste heat boiler 2. Next, the exhaust gas is supplied to the filtration dust collector 4 via a duct (not shown). And in the middle, sodium hydrogen carbonate pulverized by the fluidized pulverizer 15 is blown through the inlet of the exhaust gas passage (pipe), neutralizes the acidic gas component in the exhaust gas, and removes fly ash, The exhaust gas cleaned by the induction fan 5 is released from the chimney 6 to the atmosphere.

  As the gas introduced into the fluid pulverizer 15, exhaust gas partially branched from the exhaust gas path on the downstream side of the filtration dust collector 4 is used. The branching method can be realized by a known method. For example, the branching path can be configured by a branching valve such as a cock or a bumper, a damper, or an orifice.

  The exhaust gas branched from the exhaust gas path is sucked into the circulation gas path 11 by the blower 12 and introduced into the fluidized crusher 15 at a wind speed in a predetermined range. The exhaust gas sucked into the circulation gas path 11 and introduced into the fluidized pulverizer 15 is hot air of 140 ° C. or higher. As a result, sodium hydrogen carbonate is pulverized inside the fluidized pulverizer 15 and efficiently made porous.

  The medicine storage tank 13 stores sodium hydrogen carbonate having an average particle size of about 150 μm with good handling properties. The fixed amount supplied by the fixed amount feeder 14 is normally set as appropriate depending on the acid gas concentration at the outlet of the filtration dust collector 4.

  FIG. 3 shows an example of the fluid pulverizer 15. Hot air is supplied from a hot air duct 151 for flow at the bottom of the fluid pulverizer 15. A dispersion plate 152 having a plurality of holes is provided at the bottom of the empty tower of the fluid pulverizer 15, and the fluid medium 153 is disposed thereon. In the state where the warm air is supplied, the fluid medium 153 is blown up inside the empty tower by the warm air. In this state, when sodium hydrogen carbonate is supplied from the metering feeder 14, the sodium hydrogen carbonate is pulverized by colliding with sodium hydrogen carbonate or the fluid medium 153. In this case, the flow rate inside the empty tower is controlled to be in the range of 0.15 to 0.2 m / s so that the average particle size after the pulverization of sodium hydrogen carbonate is about 20 μm. The pulverized sodium carbonate is made substantially porous inside (inside the fluidized bed). Then, the pulverized sodium hydrogen carbonate rides on the flowing air stream and rises in the tower and is conveyed to the external circulation gas path 11. And it returns to the exhaust gas path from the circulation gas path | route 11, neutralizes the acidic gas component in exhaust gas, and is conveyed to the filtration dust collector 4. FIG. After the collision, the large coarse particles that cannot rise with the rising air flow fall again and are pulverized to a predetermined particle diameter while repeating the above steps.

  FIG. 4 shows an example of another fluid pulverizer. The fluid pulverizer having this configuration has a configuration in which an external circulation path is provided in the empty tower and a cyclone is installed in the external circulation path. By this cyclone, the fluid medium having a particle size exceeding 20 μm and the insufficiently pulverized drug can be collected and returned to the empty tower, and the drug and fluid medium having a particle diameter of 20 μm or less are conveyed to the circulation gas path 11. be able to.

  In addition, a fluid medium can be used during pulverization by the fluid pulverizer 15. As the fluid medium, cinnabar sand, aluminum oxide, or a mixture thereof can be used. In particular, cinnabar having a particle diameter of about 1 mm is preferable. The fluid medium is initially charged before operation, and is configured to replenish the carry-over amount when the furnace is shut down.

  The fluid pulverizer 15 can appropriately set the particle size of the drug, for example, sodium hydrogen carbonate, in the range of an average particle size of 10 μm to 50 μm.

  In addition, the blower 12, the quantitative feeder 14, the fluid pulverizer 15 and the branching means of the exhaust gas treatment apparatus can be controlled by individual control means, respectively, or can be controlled by a series of interlocked control means. As control means in this case, a software program for controlling the blower 12, the constant supply machine 14, the fluidized crusher 15, a branching means (branch valve, etc.), and a hardware such as a ROM, CPU, and memory for storing the software program For example, a cooperative operation configuration with a hardware resource, a configuration of a dedicated circuit, or a configuration of firmware can be exemplified.

(Embodiment 2)
The exhaust gas treatment method of the second embodiment is realized by a configuration in which the fluid pulverizer 15 is installed in the hot air circulation line. The hot air circulation line shown in FIG. 2 includes a circulation gas path 11 that branches off from the exhaust gas path on the downstream side of the filtration dust collector 4 and returns to the upstream side of the filtration dust collector 4. The warm air generating means 21, the blower 12, and the fluidized pulverizer 15 are installed in this order from the upstream side. At the time of exhaust gas generation, the hot air generation means 21 is not operated (because the exhaust gas itself is at a high temperature), and operates as in the first embodiment. On the other hand, when exhaust gas is not produced | generated, in order to prevent the function fall of the filtration dust collector 4, the warm air production | generation means 21 is operated and it is comprised so that a warm air may be produced | generated.

  The warm air generating means 21 shown in FIG. 2 can be exemplified by various heaters, for example. According to FIG. 2, the hot air generating means 21 is provided on the upstream side of the blower 12, but can also be provided on the downstream side thereof.

  When the incinerator 1 is not operating, the exhaust gas is not generated. In such a case, the exhaust gas of hot air is not introduced into the filtration type dust collector 4 and the substances accumulated on the filter surface are bound, making it difficult to remove. In order to prevent this, the blower 12 and the hot air generating means 21 are operated so as to circulate the gas in the bag filter, so that the hot air is generated and introduced into the filtering dust collector 4. The fixed amount feeder 14 and the fluid pulverizer 15 are not in operation, the fluid pulverizer 15 may be a part of the path, and a bypass path that does not pass through the fluid pulverizer 15 may be provided.

  And when the exhaust gas is not produced | generated, the control means of Embodiment 2 operates the air blower 12 and the warm air production | generation means 21, produces | generates a warm air, and controls it to introduce into the filtration type dust collector 4. Configured.

  According to the above, when the exhaust gas is generated, it operates as in the first embodiment, and when it does not generate the exhaust gas, it is configured to operate as in the second embodiment. Decline can be prevented in advance.

(Another embodiment)
In the present invention, it is also possible to restrict the particle size range by installing a cyclone downstream of the fluidized pulverizing means.

  Further, as the dust collecting means, a pulse filter type or a backwash type bag filter device, an electric dust collector or the like can be used.

  Although the structure which uses sodium hydrogencarbonate alone as a chemical | medical agent was demonstrated, this invention also has the structure which adds another chemical | medical agent (slaked lime, sodium carbonate, natural soda, sodium sesquicarbonate, etc.) suitably based on sodium hydrogencarbonate. Can be adopted. For example, BICAR (trade name) mainly composed of sodium bicarbonate is exemplified.

The figure explaining an example of an exhaust gas treatment apparatus The figure explaining an example of an exhaust gas treatment apparatus A diagram for explaining an example of a fluid mill A diagram for explaining an example of a fluid mill The figure for demonstrating the example of the conventional waste gas processing apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Incinerator 2 Waste heat boiler 3 Temperature reduction tower 4 Filtration type dust collector 5 Induction fan 6 Chimney 11 Circulating gas path 12 Blower 13 Chemical storage tank 14 Fixed supply machine 15 Fluid crusher 21 Hot air production | generation means

Claims (6)

An exhaust gas treatment method for introducing a chemical for neutralizing an acid gas component in exhaust gas into the exhaust gas, and treating fly ash and / or reaction products in the exhaust gas with a dust collecting means,
Using a sodium-based drug as the drug,
Providing a path for circulating the gas after dust collection by the dust collecting means;
Introducing the gas into the fluidized grinding means in the path,
Crushing the drug using the fluidized crushing means,
An exhaust gas treatment method, wherein the pulverized chemical is introduced to the upstream side of the dust collecting means through the path.   2. The exhaust gas treatment method according to claim 1, wherein when the exhaust gas is not generated, warm air is generated in the circulation path so as to prevent a decrease in function of the dust collecting means.   3. The exhaust gas treatment method according to claim 1, wherein in the case of chemical pulverization by the fluid pulverization means, cinnabar sand and / or aluminum oxide is used as a fluid medium.   4. In the case of chemical pulverization by the fluid pulverizing means, the superficial velocity of the fluid pulverizing means is a value in the range of 0.15 to 0.2 m / s. The exhaust gas treatment method according to item 1. An exhaust gas treatment apparatus for introducing a chemical for neutralizing an acidic gas component in exhaust gas into the exhaust gas and treating fly ash and / or reaction products in the exhaust gas with a dust collecting means,
A path for circulating the gas collected by the dust collecting means and introducing it to the upstream side of the dust collecting means;
A push-type blower for guiding the circulating gas into the path;
Fluidized crushing means for crushing the medicine on the downstream side of the push-in type blower in the path,
An exhaust gas treatment apparatus comprising: 6. The apparatus according to claim 5, further comprising hot air generating means for generating hot air in the circulation path so as to prevent a decrease in function of the dust collecting means when the exhaust gas is not generated. The exhaust gas treatment apparatus described in 1.

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