JP2002219335A - Exhaust gas treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas treating device capable of totally treating organic compounds, particularly a harmful aromatic hydrocarbon and dioxins, a dust such as burned flying ash, heavy metals, acidic gas and nitrogen oxides and maintaining the performance for a long period of time. SOLUTION: The exhaust gas treating device is provided with a gas cooling means for cooling an exhaust gas discharged from a furnace such as an incinerator and a fusion furnace, a catalyst carrying bag filter for eliminating a harmful component in an exhaust gas cooled by the gas cooling means, and an exhaust gas flue communicating with the gas cooling means and the catalyst carrying filter. The exhaust gas dust-eliminating device is provided on the exhaust gas flue. A means for feeding an acidic gas eliminating agent and an adsorbing agent is provided on the flue at a front flow of the exhaust gas dust-eliminating device and a means for feeding a reducing agent is provided on the flue at a rear flow of the exhaust gas dust-eliminating device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment apparatus, and is particularly suitable for comprehensively reducing organic compounds such as heavy metals, alkali metals, acidic gases, nitrogen oxides, and dioxins contained in exhaust gas. The present invention relates to a simple exhaust gas treatment device.

[0002]

2. Description of the Related Art Today, incineration is the mainstream in the treatment of municipal waste and the like, and the exhaust gas generated by this incineration includes dust, hydrogen chloride, sulfur oxides, nitrogen oxides and the like. In addition, since harmful substances such as organic compounds such as dioxins are contained, various methods for removing these harmful substances have been proposed. For example, JP-A-1-155
Japanese Unexamined Patent Publication No. 937 proposes an exhaust gas treatment method for a refuse incinerator that can improve the removal rate of acidic components in combustion exhaust gas to suppress generation of harmful organic chlorine compounds and efficiently reduce the compounds. Have been. FIG. 12 shows a system diagram of the above-described conventional exhaust gas treatment apparatus. In FIG. 12, an exhaust gas treatment device includes an incinerator 1a, a gas cooling device 3, a cooling tower 4, and a gas cooling device 3, which are sequentially connected to the incinerator 1a via an exhaust gas flue.
It is mainly composed of an exhaust gas dust remover 5a and a bag filter 6c.
An acid gas remover 15 for neutralizing and removing the acid gas in the exhaust gas is supplied to the flue 17 communicating with c.

In such a configuration, municipal solid waste and the like are supplied to the incinerator 1a by the supply device 2 and burned and incinerated. The combustion exhaust gas of 750 to 950 ° C. generated at this time is approximately 250 to 150 ° C. in the gas cooling device 3 and the cooling tower 4.
After being cooled to 0 ° C., it is supplied to an exhaust gas dedusting device 5a to collect dust in the exhaust gas.
It is reduced to about 0 to 50 mg / Nm ³ . Further, the exhaust gas is mixed with an acid gas remover 15 such as slaked lime while passing through the flue 17 and supplied to the bag filter 6c. The exhaust gas passing through the bag filter 6c is passed through the suction blower 7 from the chimney 8 via the suction blower 7 as clean gas. It is discharged out of the system. In the bag filter 6c, the acid gas remover 15 is collected together with a small amount of dust contained in the exhaust gas to form a layer. By forming this layer, the contact efficiency between the acidic gas in the exhaust gas and the acidic gas removing agent 15 is improved, so that the acidic components in the exhaust gas are removed with high efficiency, and the exhaust gas temperature is 250 to 150 ° C.
, Formation of harmful organic chlorine compounds is suppressed. Further, since most of the dust is collected and removed by the exhaust gas dedusting device 5a, the bag filter 6c is removed.
The amount of dust adhering to the filter is reduced, and the load on the bag filter is reduced.

On the other hand, the incinerated fly ash 9 collected by the gas cooling device 3, the cooling tower 4, the exhaust gas dedusting device 5a and the bag filter is collected by an ash crane 10 and passed through a fly ash supply device 11 to an ash treatment device. The treated ash 13 is discharged to the outside as a treated ash 13. The collected ash containing the unreacted acid gas remover 15 collected by the bag filter 6c is circulated to the flue 17 via the acid gas remover circulation pipe 33 and reused. In the above-mentioned conventional technique, the temperature of the exhaust gas in the bag filter is cooled to a temperature lower than the generation temperature of organic compounds, and the fly ash 9 in the exhaust gas is removed in advance to remove the acid gas remover 15.
And acidic components (HCl, SOx, etc.) in the exhaust gas are efficiently reacted to reduce the acidic components, thereby suppressing the production of organic compounds such as dioxin. However, regeneration of organic compounds in the gas cooling device 3 or the like cannot be suppressed,
Further, the organic compounds themselves cannot be directly decomposed and removed by the bag filter, and there is a problem that the gaseous organic compounds are discharged out of the system through the bag filter.

FIG. 13 is a system diagram of an exhaust gas treatment apparatus showing another conventional technique. This device is the Japanese Patent Publication No. 7-103980.
No. 1993. 13 differs from FIG. 12 in that a first bag filter 5c is used as the exhaust gas dedusting device 5a, and a second bag filter 6b is used as the bag filter 6c.
And a neutralization reaction tower 34 is installed in the exhaust gas flue 17 between the first bag filter 5a and the second bag filter 6b. The acidic exhaust gas remover circulation pipe 33 is not provided. In such a configuration, the first bag filter 5
The acid gas remover 15 is supplied to the exhaust gas from which the dust in the exhaust gas has been removed in step c, and the neutralized product generated in the neutralization reaction or the like 34 is collected and removed by the second bag filter 6b. The amount of collected fly ash containing neutralized products such as debris is greatly reduced, and ash processing costs can be reduced. However, as in the case of FIG. 12, only the organic compounds adsorbed on the acidic gas remover 15 can be removed by the second bag filter, and the amount thereof is small, and the gaseous organic compounds cannot be removed. There was a problem.

FIG. 14 is a system diagram of an exhaust gas treatment apparatus showing still another conventional technique. This device is Japanese Patent Publication 4-367.
No. 29 has proposed this. In FIG. 14, FIG.
The difference from this is that the bag filter 6c is replaced with a catalyst-carrying bag filter 6a, and the flue gas exhaust system 14 communicating the cooling tower 4 and the catalyst-carrying bag filter 6a is not provided with an exhaust gas dedusting device 5a. The acidic gas remover 15, the reducing agent 18, and the filter aid 35 are added to the catalyst support bag filter 6a.
Thus, in addition to the removal of the incineration fly ash 9, the removal of acidic components and the removal of nitrogen oxides are simultaneously performed. Note that the acid gas remover circulation pipe 33 is not provided.

[0007] The exhaust gas treatment apparatus is a multifunctional integrated apparatus, and can reduce equipment costs, save space, and save energy. However, in such a configuration, since the neutralization reaction between the acidic component in the exhaust gas and the acidic gas removing agent 15 is mainly performed on the catalyst-carrying filter, a large amount of unreacted acidic component is present in the flue 14, Since the acidic component reacts preferentially with the reducing agent 18 such as ammonia or urea, it is necessary to add a large amount of the reducing agent in order to sufficiently perform the reduction reaction of nitrogen oxides. The neutralized product produced by reacting with the acidic component has a hygroscopic property, adheres to the catalyst-carrying bag filter and closes the pores of the catalyst component,
In order to reduce the catalyst activity, it was necessary to add a filter aid 35 to form a filter aid layer on the surface of the catalyst-carrying bag filter 6a. Since this filter aid layer is removed at the same time when the catalyst-supporting bag filter is backwashed, it is necessary to form the filter aid layer each time, which is not practical. Although there is no description about the removal of organic compounds, it is considered that the performance of removing organic compounds is also reduced due to the decrease in the activity of the catalyst as described above.

FIG. 15 is a system diagram of another conventional exhaust gas treatment apparatus. In FIG. 15, the exhaust gas generated in the furnace 1 c passes through the gas cooling device 3 and the cooling tower 4.
It is cooled to about 0 ° C., and the acid gas remover 15
The adsorbent 16 and the filter aid 35 are charged, and acidic components such as hydrogen chloride and heavy metals are removed on the downstream bag filter 6b. The denitration reaction is performed in the catalyst tower 37 together with the reducing agent 18 such as ammonia which is heated and blown into the flue 38. In this catalyst tower 37, denitration and dioxin removal are also performed using a catalyst effective for removing dioxins.

In the above prior art, the exhaust gas at the outlet of the bag filter 6b needs to be reheated to the catalyst activation temperature of 350 to 450 ° C., which has a problem in terms of thermal efficiency. Further, when the exhaust gas is reheated, the resynthesis of dioxins proceeds, so that it is necessary to increase the amount of the catalyst packed in the catalyst tower 37. Furthermore, when treating exhaust gas with a high concentration of heavy metals, the concentration of heavy metals passing through the bag filter tends to increase, depending on the form of the heavy metals in the exhaust gas (fine particles, vapor, fume). There is a problem that the heavy metals in various forms passing through the filter 6b are vaporized or fume by reheating by the air heater 36, act on the catalyst filled in the catalyst tower 37, and reduce the activity. Further, calcium and ammonia in the exhaust gas pass through the bag filter and adhere to the catalyst tower 37 little by little, so that the catalytic activity tends to decrease with time. The catalyst of the catalyst tower 37 is filled in a state coated on a solid support such as a plate or a honeycomb, and the exhaust gas collides with the coated surface of the catalyst, and the organic compounds and the like in the exhaust gas in the process of being reflected and passed. Is decomposed by reacting with the catalyst, but since the only part that acts as a catalyst is the surface coated with the catalyst carrier, if dust or the like adheres to the surface, the catalytic activity is significantly reduced.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned problems of the prior art, and to reduce organic compounds, particularly harmful aromatic hydrocarbons and dioxins, dusts such as incinerated fly ash, and heavy metals. It is an object of the present invention to provide an exhaust gas treatment apparatus capable of comprehensively treating water, acid gas, and nitrogen oxides and maintaining its performance for a long period of time.

[0011]

Means for Solving the Problems The present inventors diligently studied the above-mentioned problems, and as a result of a verification test using an actual machine, the use of a catalyst-carrying bag filter enabled organic compounds adhering to dust in exhaust gas to be reduced. It is removed together with the dust collected by the catalyst supporting bag filter, and a part of the gasified organic compounds are decomposed by the supported catalyst,
In addition, a dust removal device is installed upstream of the catalyst carrying bag filter,
An acid gas remover, etc., is supplied to the exhaust gas flue upstream of that to neutralize the acid gas in the exhaust gas, and the neutralized products are collected and removed together with the dust by a dust remover, causing the catalyst to deteriorate. It has been found that the catalyst deterioration of the catalyst-carrying bag filter can be effectively prevented by removing in advance the substance to be used, and the present invention has been achieved. The invention claimed in the present application to achieve the above object is as follows.

(1) Gas cooling means for cooling exhaust gas discharged from a furnace such as an incinerator or melting furnace, a catalyst-carrying bag filter for removing harmful components in the exhaust gas cooled by the gas cooling means, In an exhaust gas treatment device provided with an exhaust gas flue communicating with a gas cooling unit and a catalyst carrying filter, an exhaust gas dust removal device is provided in the exhaust gas flue, and an acid gas remover is provided in a flue upstream of the exhaust gas dust device. An exhaust gas treatment apparatus comprising: means for supplying an adsorbent; and means for supplying a reducing agent to a flue downstream of the exhaust gas dust removal device. (2) The exhaust gas treatment device according to (1), wherein the exhaust gas dust removal device is a bag filter. (3) further provided with an ash melting furnace for melting the ash collected by the exhaust gas dust removing device and the catalyst-carrying bag filter, and cooling means for the ash melting furnace exhaust gas for cooling the ash melting furnace exhaust gas generated in the ash melting furnace; In addition, (1) or (2), there is further provided means for joining the ash melting furnace exhaust gas cooled by the ash melting furnace exhaust gas cooling means to a flue near a gas outlet of the gas cooling means. An exhaust gas treatment apparatus according to (1).

(4) An ash melting furnace exhaust gas dust remover is further provided downstream of the ash melting furnace exhaust gas cooling means, and the ash melting furnace exhaust gas flue upstream of the ash melting furnace exhaust gas dust remover is provided with an acidic gas. Means for supplying a gas removing agent and an adsorbent are further provided, and the ash melting furnace exhaust gas removed by the ash melting furnace exhaust gas removing device is provided near the gas outlet of the gas cooling means or near the gas outlet of the exhaust gas removing device. The exhaust gas treatment apparatus according to (3), further comprising means for merging with the flue. (5) a gas cooling means for cooling exhaust gas discharged from a furnace such as an incinerator or a melting furnace, a catalyst-carrying bag filter for removing harmful components in the exhaust gas cooled by the gas cooling means, and the gas cooling means And an exhaust gas flue that communicates with the catalyst-carrying filter, and a means for supplying an acid gas remover and a reducing agent to the exhaust gas flue, wherein the ash collected by the catalyst-carrying bag filter is melted. Ash melting furnace, ash melting furnace exhaust gas cooling means for cooling the ash melting furnace exhaust gas generated in the ash melting furnace, and ash melting for removing the ash melting furnace exhaust gas cooled by the ash melting furnace exhaust gas cooling means A method for supplying an acid gas remover and an adsorbent to the flue gas of an ash-melting furnace exhaust gas which communicates the ash-melting-furnace exhaust gas cooling device and the ash-melting furnace exhaust-gas dust removal device with a furnace exhaust gas dust-removing device. And means for merging the ash-melting furnace exhaust gas removed by the ash-melting furnace exhaust gas dust-removing device into a flue upstream of the catalyst-carrying bag filter and upstream of a means for supplying a reducing agent. An exhaust gas treatment device characterized by being provided. (6) The exhaust gas treatment device according to (4) or (5), wherein the dust removal device for exhaust gas from ash melting furnace is a bag filter.

[0014]

According to the present invention, a dust removal device is provided between a gas cooling device such as a gas cooling device or a cooling tower and a catalyst-carrying bag filter to remove dust in advance of the catalyst-carrying bag filter. Therefore, the dust load on the catalyst-carrying bag filter is reduced, the differential pressure hardly rises, the frequency of backwashing and other treatments is reduced, the problem of falling off of the supported catalyst due to backwashing is eliminated, and the catalyst performance is improved. Can be maintained for a long time. Further, since the load on the bag filter is reduced, the number of furnace cloths or the area of the furnace cloth can be reduced as compared with a case where dust is collected by a catalyst-carrying bag filter. In addition, an acid gas remover such as slaked lime and an adsorbent are introduced into an exhaust gas flue connecting the gas cooling means and the exhaust gas dust remover, and hydrogen chloride (HCl) and nitrogen oxide (SOx) are introduced.
By neutralizing acidic gases such as, etc., and adsorbing heavy metals in the exhaust gas with an adsorbent, and removing these products together with the dust in a downstream exhaust gas dust remover, the components that cause catalyst deterioration are reduced. Thus, the catalyst performance of the catalyst-carrying bag filter can be maintained for a long period of time. In addition, acid gas, which is a regeneration factor for organic compounds, and heavy metals that act as a catalyst during regeneration are removed in front of the catalyst-supporting bag filter, so that regeneration of organic compounds in the catalyst-supporting bag filter is suppressed. As a result, the concentration of organic compounds can be reduced.

Furthermore, a reducing agent for mainly reducing nitrogen oxides in the exhaust gas is introduced into the exhaust gas flue between the exhaust gas dust removing device and the catalyst-carrying bag filter, and the nitrogen oxides are reduced by the catalyst-carrying bag filter. At the same time as being harmless, organic compounds in the exhaust gas are also decomposed and removed by contact with the catalyst, so two-stage exhaust gas such as conventional electric dust collectors and bag filters, cyclones and bag filters, and bag filters and bag filters. The concentration of the organic compounds can be further reduced as compared with a method in which the regeneration of the organic compounds is suppressed indirectly by the treatment. Furthermore, since the acidic gas can be removed upstream of the catalyst-carrying bag filter, the reducing agent is not wasted by the acid gas even if the reducing agent is introduced into the exhaust gas flue, and the nitrogen on the catalyst-carrying bag filter is reduced. The reduction reaction of the oxide can effectively proceed. In addition, the effective amount of the reducing agent changes due to the change in the concentration of the acidic gas, and the problem that the reduction reaction is not sufficiently performed is eliminated, and the control of the amount of the reducing agent to be introduced becomes easy. Further, reheating of exhaust gas is not necessary as in the case of a catalyst tower, and waste in thermal efficiency is eliminated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of an exhaust gas treatment apparatus showing one embodiment of the present invention. 1 is different from FIG. 12 in that a bag filter 6c is a catalyst-carrying bag filter 6a, and an acid gas remover 15 and an adsorbent 16 are supplied to a flue 14 that connects the cooling tower 4 and the exhaust gas dedusting device 5a. In addition, a reducing agent 18 is supplied to a flue 17 which communicates the exhaust gas dedusting device 5a with the catalyst-carrying bag filter 6a. In addition, the acidic gas removal circulation pipe 33 is not provided.

In such a configuration, the exhaust gas discharged from the incinerator 1a is cooled to about 200 ° C. in the gas cooling device 3 and the cooling tower 4 and mixed with the acid gas remover 15 such as slaked lime in the flue 14. Hydrogen chloride (HC)
l), acid gases such as sulfur oxides (SOx) are neutralized,
The neutralized product is collected and removed as incineration fly ash 9 together with the dust in the exhaust gas dedusting device 5a in the downstream. The concentration of the dust in the exhaust gas depends on the type of refuse to be incinerated and the combustion conditions, but is usually 6000 to 8000 mg / Nm ³ ,
This is, for example, 30-50 mg /
It is removed up to Nm ³ . When the exhaust gas contains a large amount of heavy metals, the adsorbent 16 containing at least one of activated carbon, a metal compound that causes an amalgam synthesis reaction, a metal halide compound, diatomaceous earth, and porous fine particles such as zeolite is used as a flue gas. 14 and the exhaust gas dedusting device 5
The heavy metals adsorbed on the adsorbent 16 are removed at a.

The exhaust gas from which the dust, acid gas and heavy metals have been removed by the exhaust gas dedusting device 5a contains a small amount of dust, nitrogen oxides (NOx) and aromatics generated during the combustion process and the exhaust gas cooling process. Organic compounds such as hydrocarbons and dioxins, in particular, gaseous organic compounds (dioxins) are included. These exhaust gases are further supplied to a flue 17 by a reducing agent 18 such as ammonia or urea.
And supplied to the catalyst-carrying bag filter 6a, where nitrogen oxides (NOx) and organic compounds in the exhaust gas are efficiently decomposed and removed by contact with the supported catalyst without being disturbed by acidic gases and heavy metals. Is done. That is, although it depends on the type of the exhaust gas dust removal device 5a, the dust that has passed through the exhaust gas dust removal device 5a still contains dust of about ³⁰ to 50 mg / Nm ³ , and the temperature of the exhaust gas passes through the flue. The dioxins and the like in the exhaust gas adhere to the dust as fumes and move, and are removed together with the particulate dioxins by the downstream catalyst-carrying bag filter, and the gaseous dioxins are further removed by the supported catalyst. Is decomposed and removed by the action of The nitrogen oxides are rendered harmless by a reduction reaction with a catalyst under the condition of the charging of the reducing agent 18. Further, the dust concentration is further reduced.

As described above, an exhaust gas dedusting device is provided upstream of the catalyst-carrying bag filter, and an acid gas remover and an adsorbent are supplied to the exhaust gas flue upstream of the exhaust gas flue gas to neutralize the acid gas in the exhaust gas. By adsorbing heavy metals and collecting and removing substances that cause catalyst deterioration in advance, catalyst deterioration of the catalyst-supporting bag filter is prevented, and a reducing agent is added to the exhaust gas flue downstream of exhaust gas dedusting. By supplying the catalyst, the reduction reaction of nitrogen oxides in the catalyst-carrying bag filter can be efficiently performed. Further, by using the catalyst-carrying bag filter, not only the organic compounds attached to the dust but also the gasified organic compounds can be used. Can also be decomposed and removed by catalysis. Therefore, according to the exhaust gas treatment apparatus of the present invention, it is possible to comprehensively treat organic compounds such as aromatic hydrocarbons and dioxins, dust, heavy metals, acidic gases, nitrogen oxides, and the like in exhaust gas, and have a long processing time. Its performance can be maintained over time.

The apparatus shown in FIG. 1 is an example of the present invention, and various types can be adopted for the incinerator 1, the gas cooling apparatus 3, the cooling tower 4, the exhaust gas dedusting apparatus 5a and the like. It is not limited to a device. Furthermore, various conditions such as operating conditions, materials, sizes, shapes and the like can be used for the catalyst-carrying bag filter 6a. Any form of filter can be used. In addition, the gas cooling device 3 and the cooling tower 4 do not particularly need both, and it is sufficient that at least one of the devices having the same function is provided as needed. As the exhaust gas dedusting device 5a, various devices such as an electric dust collector and a cyclone which are generally used are used. Further, as shown in FIG. 2, the bag filter 5b may be used as an exhaust gas dedusting device, or the bag filter 5b may be used by supporting a catalyst. In the latter case, it is preferable to add a filter aid, a coating agent, and the like to the flue 14 as necessary in order to suppress a decrease in the catalyst activity with time. On the other hand, the incinerated fly ash 9 collected by the gas cooling device 3, the cooling tower 4, the exhaust gas dedusting device 5a and the catalyst carrying bag filter 6a is processed by the ash treatment device 12 through the ash crane 10 and the fly ash supply device 11. And is collected as treated ash 13.
2 may be replaced with an ash melting furnace, a cement solidifying device, a chemical treatment device, a sintering furnace, or the like.

FIG. 3 is a cross-sectional view of a bag house in which a bag filter and a catalyst-carrying bag filter are incorporated. In the present invention, a device in which such an exhaust gas removing device and a catalyst-carrying bag filter are integrated is used. Can be. In FIG. 3, the exhaust gas is supplied into the bag house 60 through the flue 14 into which the acid gas remover 15 and the adsorbent 16 are blown, and the flue 45 formed by the bag filter 39, the partition plates 43 and 44, and the catalyst. The gas is supplied to the carrying bag filter 40 in order, processed, and discharged out of the bag house 60 as a clean gas. On the other hand, incineration fly ash 9 is collected from the bottoms of the bag filter 39 and the catalyst-carrying bag filter 40.
Reference numerals 41 and 42 denote baffle plates, and a flue 45 is supplied with a reducing agent 46. The inside of the bag house 60 is divided into two parts by a partition plate 44 installed in the meridional direction, but the same effect can be obtained by dividing it into two or more parts.

FIG. 4 is an explanatory sectional view of a bag house in which a cyclone type dust remover and a catalyst-carrying bag filter are incorporated. FIG. 5 is a sectional view taken along line AA of FIG. The inside of the baghouse 60 is vertically divided into two parts by a flue 50 formed by a convex upward conical baffle plate 48 and a downward conical baffle plate 49 which are provided in the central portion and arranged in the weft direction.
The lower part has a cyclone chamber, and the catalyst-carrying bag filter 40 is arranged at the upper part. In such a configuration, the exhaust gas is blown from the flue 14 in the tangential direction of the bag house 60, and is easily dusted in the cyclone chamber. Then, the gas is supplied to the catalyst-carrying bag filter 40 through the flue 54, and the purified gas is discharged out of the system. The baffle plate 4
There is no limitation on the specifications of 8 and 49, and the material is also a material that does not allow dust to pass through, such as a woven cloth, a cloth such as felt used for a bag filter, a perforated plate such as ceramic or metal, and a flat plate. Can be used. Also, the AA cross section of the bag house does not need to be circular, and can be formed in various shapes, but a circular shape is more suitable as a cyclone.

FIG. 6 is a system diagram of an exhaust gas treatment apparatus according to another embodiment of the present invention. 6 differs from FIG. 1 in that a melting furnace 19 is provided in place of the ash treatment device 12, and furthermore, a flue 21 and a cooling tower 22 are provided downstream, and the cooling tower 22 cools to about 200 ° C. However, the point is that the exhaust gas of the melting furnace is merged with the flue 14 near the gas outlet of the cooling tower 4 through the flue 23. According to such a device,
As with the exhaust gas treatment apparatus shown in FIG. 1, harmful components in the exhaust gas can be comprehensively removed, the performance of the exhaust gas can be maintained for a long time, and the incinerated fly ash 9 to be collected and recovered is melted in a melting furnace 19. Since the molten slag is discharged out of the system as molten slag 20, ash processing costs can be significantly reduced.

Further, alkali metals such as Na, K, Ca, etc., heavy metals and acid gas in the exhaust gas of the melting furnace are collected again by the exhaust gas dust removal device 5a and returned to the melting furnace 19, so that Concentration may progress. In this case, as shown in FIG. 7, an exhaust gas dedusting device 26 is provided downstream of the cooling tower 22,
It is preferable that the acid gas remover 15 and the adsorbent 16 are supplied, and the exhaust gas dedusting device 26 collects the acid gas, heavy metals, and the like in the exhaust gas of the melting furnace as molten fly ash 27. When the concentration of alkali metals such as Na, K and Ca, heavy metals and acid gases such as HCl and SOx in the incineration exhaust gas generated from the incinerator 1a is not high,
As shown in FIG. 8, the exhaust gas dedusting device 5a may be omitted, and the molten exhaust gas flue 23 may be joined to the flue 14 upstream of the catalyst-carrying bag filter 6a. In this case, if possible, it is preferable to join them on the upstream side from the inlets of the acid gas removing agent 15, the adsorbent 16 and the reducing agent 18.

FIG. 9 is a system diagram of an exhaust gas treatment apparatus showing still another embodiment of the present invention. 9 is different from FIG. 1 in that a melting furnace 1b is provided instead of the incinerator 1a, and the solid content subjected to the melting treatment is used as a melting slag 20 in the melting furnace 1
The point is that only the temperature-reducing tower 4 is installed as a gas cooling means while the molten fly ash 27 discharged from these devices is recovered by the ash crane 11 while being recovered from the bottom of b. The treatment of the molten fly ash 27 can be performed by a commonly used method such as solidification of a drug, solidification of a cement, and a reduction method. Even in such an apparatus, harmful components can be comprehensively treated similarly to the exhaust gas treatment apparatus shown in FIG. 1, and its performance can be maintained for a long period of time. The above equipment is used for various types of combustion furnaces such as metal processing furnaces such as aluminum melting furnaces, blast furnaces, and industrial waste incinerators,
It can be similarly used in melting furnaces and firing furnaces.

FIG. 10 and FIG. 11 are system diagrams of an exhaust gas treatment apparatus showing still another embodiment of the present invention. FIG. 10 differs from FIG. 9 in an example in which the melting furnace 1b is changed to a waste gasification melting furnace and applied. The present apparatus includes a gasifier 1c instead of the incinerator 1a. Gas generated in the gas furnace 1c is separated from char by a separator 28 and supplied to a power generation turbine 29 to perform power generation processing and the like.
On the other hand, the separated char is supplied to a melting furnace 31 through a char supply pipe 30 and melted, a molten slag 32 is discharged out of the system, and the exhaust gas from which the char has been removed is subjected to an exhaust gas treatment device such as a cooling tower 4. And the same processing as in the apparatus of FIG. 9 is performed. In addition, as shown in FIG. 11, the generated gas may be supplied to the melting furnace 31 together with the char to assist the self-thermal melting of the char. In this case, the separator 28 need not be particularly provided.

[0027]

According to the present invention, the following effects can be obtained. 1) Since the dust contained in the exhaust gas is removed in advance in the upstream of the catalyst-carrying bag filter, the dust load on the catalyst-carrying bag filter is reduced, the pressure difference hardly increases, and the frequency of processing such as backwashing is reduced. Since the amount of the catalyst is reduced, there is no problem that the supported catalyst falls off due to the backwashing treatment, and the performance can be maintained for a long period of time. Further, since the load is reduced, the number of furnace cloths or the filtration area can be reduced as compared with the case where the catalyst-carrying bag filter is installed alone. 2) Before the catalyst-carrying bag filter, acid gas and heavy metals that cause catalyst deterioration are removed, so that the catalyst performance can be maintained for a long time. 3) In the upstream of the catalyst-carrying bag filter, acid gas as a regenerating factor of organic compounds and heavy metals acting as a catalyst at the time of regeneration are removed. And organic compounds are decomposed and removed by the supported catalyst, so that the concentration of the organic compounds can be greatly reduced. 4) Compared with the conventional two-stage exhaust gas treatment (electrostatic precipitator + bag filter, cyclone + bag filter, bag filter + bag filter), the catalyst-supporting bag filter is located behind the catalyst-supporting bag filter. Because it was installed in the flow,
The gasified organic compounds in the exhaust gas can also be directly decomposed and removed, and the concentration of the organic compounds can be greatly reduced. 5) Since the acidic gas can be removed upstream of the catalyst-carrying bag filter, when the reducing agent is introduced into the flue between the exhaust gas dedusting device and the catalyst-carrying bag filter, the reducing agent is wasted by the acid gas. And the reduction reaction of nitrogen oxides on the catalyst-carrying bag filter can be effectively advanced. Further, the effective amount of the reducing agent changes due to the fluctuation of the concentration of the acidic gas, and the problem that the reduction reaction is not sufficiently performed is eliminated, and the control of the amount of the reducing agent to be introduced becomes easy.

[Brief description of the drawings]

FIG. 1 is a system diagram of an exhaust gas treatment apparatus showing one embodiment of the present invention.

FIG. 2 is a system diagram of an exhaust gas treatment apparatus showing another embodiment of the present invention.

FIG. 3 is a sectional view of an integrated log house that can be used in the present invention.

FIG. 4 is a sectional view of another integrated log house that can be used in the present invention.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a system diagram of an exhaust gas treatment apparatus showing still another embodiment of the present invention.

FIG. 7 is a system diagram of an exhaust gas treatment apparatus showing still another embodiment of the present invention.

FIG. 8 is a system diagram of an exhaust gas treatment apparatus showing still another embodiment of the present invention.

FIG. 9 is a system diagram of an exhaust gas treatment apparatus showing still another embodiment of the present invention.

FIG. 10 is a system diagram of an exhaust gas treatment apparatus showing still another embodiment of the present invention.

FIG. 11 is a system diagram of an exhaust gas treatment apparatus showing still another embodiment of the present invention.

FIG. 12 is a system diagram of a conventional two-stage exhaust gas treatment apparatus.

FIG. 13 is a system diagram of a two-stage exhaust gas treatment apparatus according to another conventional technique.

FIG. 14 is a system diagram of an exhaust gas treatment device provided with a catalyst-carrying bag filter according to a conventional technique.

FIG. 15 is a system diagram of an exhaust gas treatment device provided with a conventional catalyst tower.

[Explanation of symbols]

1a: Incinerator, 1b: Melting furnace, 1c: Gas furnace, 2: Supply device, 3 ... Gas cooling device, 4 ... Cooling tower, 5a: Exhaust gas dust removal device, 5b: Bag filter, 5c: First bag filter Reference numeral 6a: catalyst-carrying bag filter, 6b: second bag filter, 7: suction blower, 8: chimney, 9: incineration fly ash, 10
... Ash crane, 11 ... Fly ash supply device, 12 ... Ash treatment device, 12 ... Ash, 14 ... Flue, 15 ... Acid gas remover, 16 ... Adsorbent, 17 ... Flue, 18 ... Reducing agent, 19 …
Melting furnace, 20: molten slag, 21, 23: flue, 22:
Cooling tower, 24 flue, 26 flue gas dedusting device, 27 molten fly ash, 28 separator, 29 power generation turbine, 31
Melting furnace, 32: molten slag, 33: exhaust gas remover circulation pipe, 34: neutralization reaction tower, 35: filter aid, 36: air heater, 37: catalyst tower, 38: flue, 39: bag filter, 40 ... Catalyst-carrying bag filter, 41, 42 baffle plate, 43, 44 partition plate, 45 flue, 46 reducing agent supply device, 47 partition plate, 48, 49 baffle plate, 5
0 ... flue.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D002 AA02 AA19 AA28 AB01 AC04 AC10 BA03 BA04 BA14 CA13 DA05 DA12 DA41 DA45 EA01 FA03 4D004 AA37 AB03 CA29 4D048 AA06 AA11 AA17 AC03 AC04 BC04 CA07 CC39 CC41 CC61 CD01 CD03 CD05 CD08

Claims (6)

[Claims] 1. A gas cooling means for cooling exhaust gas discharged from a furnace such as an incinerator or a melting furnace, a catalyst-carrying bag filter for removing harmful components in the exhaust gas cooled by the gas cooling means, and the gas In an exhaust gas treatment device provided with a cooling means and an exhaust gas flue communicating with a catalyst-carrying filter, an exhaust gas dust removal device is provided in the exhaust gas flue, and an acid gas remover and an adsorbent are adsorbed in a flue upstream of the exhaust gas dust device. An exhaust gas treatment apparatus comprising: means for supplying a reducing agent; and means for supplying a reducing agent to a flue downstream of the exhaust gas removing device. 2. The exhaust gas treatment device according to claim 1, wherein the exhaust gas dust removal device is a bag filter. 3. An ash melting furnace for melting ash collected by the exhaust gas dust removing device and the catalyst-carrying bag filter, and an ash melting furnace exhaust gas cooling means for cooling ash melting furnace exhaust gas generated in the ash melting furnace. 2. The apparatus according to claim 1, further comprising a unit configured to join the ash melting furnace exhaust gas cooled by the ash melting furnace exhaust gas cooling unit to a flue near a gas outlet of the gas cooling unit. 3. The exhaust gas treatment device according to 2. 4. An ash melting furnace exhaust gas dust remover is further provided downstream of the ash melting furnace exhaust gas cooling means, and an acid gas is supplied to the ash melting furnace exhaust gas flue upstream of the ash melting furnace exhaust gas remover. A means for supplying a remover and an adsorbent is further provided, and the ash melting furnace exhaust gas removed by the ash melting furnace exhaust gas dust remover is provided near a gas outlet of the gas cooling means or near a gas outlet of the exhaust gas dust remover. 4. The exhaust gas treatment device according to claim 3, further comprising means for merging with the flue. 5. A gas cooling means for cooling exhaust gas discharged from a furnace such as an incinerator, a melting furnace, etc .; a catalyst-carrying bag filter for removing harmful components in the exhaust gas cooled by the gas cooling means; An ash trapped by the catalyst-carrying bag filter is provided in an exhaust gas treatment apparatus comprising: an exhaust gas flue that communicates a cooling unit and a catalyst-carrying filter; and a unit that supplies an acid gas remover and a reducing agent to the exhaust gas flue. Ash melting furnace for melting the ash melting furnace, ash melting furnace exhaust gas cooling means for cooling the ash melting furnace exhaust gas generated in the ash melting furnace, and removing the ash melting furnace exhaust gas cooled by the ash melting furnace exhaust gas cooling means Provide an ash melting furnace exhaust gas dust remover and supply an acid gas remover and an adsorbent to the ash melting furnace exhaust gas flue that connects the ash melting furnace exhaust gas cooling device and the ash melting furnace exhaust gas dust remover. Ash-melting furnace exhaust gas removed by the ash-melting-furnace exhaust gas dust-removing device is combined with the flue gas upstream of the catalyst-carrying bag filter and upstream of the means for supplying a reducing agent. An exhaust gas treatment device comprising means. 6. The exhaust gas treatment apparatus according to claim 4, wherein the ash melting furnace exhaust gas dust removal apparatus is a bag filter.