JP3225214B2 - Equipment for treating exhaust gas, collected ash, etc. and its treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facility for treating exhaust gas, collected ash and the like in a refuse incineration facility for incinerating refuse such as general waste and industrial waste, and a method for treating the same.

[0002]

2. Description of the Related Art Exhaust gas discharged from refuse incineration facilities contains toxic dioxins in addition to soot and dust, and various kinds of dioxins are required to decompose and remove these dioxins. Measures have been taken.

FIG. 6 is a schematic diagram showing the configuration of a conventional refuse incineration facility disclosed in Japanese Patent Application Laid-Open No. 5-23539.

[0006] In FIG. 6, reference numeral a denotes a combustion furnace, and a boiler c is continuously provided through a gas mixing chamber b provided at an outlet side of the combustion furnace a, and the temperature of the exhaust gas falls to 600 to 700 ° C. , A high-temperature dust collector d is installed.

A reaction tower f having a sprayer e at the head and a bag filter h having a screw conveyor g at the bottom are connected on the exhaust side of the boiler c. And is released into the atmosphere from the chimney j.

On the other hand, a chute pipe k, a conveyor m, and a bucket elevator n are connected to the discharge side of the screw conveyor g, and collected ash removed from the bag filter h is collected by the chute pipe k, the conveyor m. ,
It is sent through a bucket elevator n to a chute p installed above the combustion furnace a.

Next, a description will be given of a process of treating exhaust gas, fly ash, and the like in the refuse incineration facility configured as described above.

[0008] The flue gas of about 800 ° C containing fly ash composed of incombustibles and unburned matter generated from the combustion furnace a and acidic toxic gas and dioxins is reburned in the gas mixing chamber b. After that, it is introduced into the boiler c and cools down.
The fly ash contained is filtered and removed by the high-temperature dust collector d in the high-temperature zone of 00 ° C. or higher, and even a small amount of organochlorine compounds attached to the fly ash generate dioxins.
Most are designed to be pyrolyzed.

Next, the exhaust gas subjected to the primary treatment is introduced into the reaction tower f, and the contained acidic harmful gas is neutralized by an alkali agent such as slaked lime slurry sprayed from the sprayer e.

The bag filter h in the next step filters and removes fly ash, organochlorine compounds, neutralization reaction products, and unreacted chemicals that could not be removed by the high-temperature dust collector d, and purifies the exhaust gas. The gas is sucked by the induction ventilator i and released into the atmosphere from the chimney j.

The collected ash collected by the bag filter h is properly removed and then passed through a screw conveyor g, a chute pipe k, a conveyer m, and a bucket elevator n from a chute p into a combustion furnace a. About 800 ° C
The organic chlorine compound, the neutralization reaction product, and the unreacted chemical are thermally decomposed in the gas mixing chamber b, and the remaining trapped ash is removed from the combustion furnace a.
And are discharged to the outside from recovery ports q and r provided at the bottom of the boiler c.

[0012]

In the above-mentioned conventional refuse incineration plant, calcium chloride as a reaction product and slaked lime as an unreacted chemical collected by a bag filter h and returned to a gas mixing chamber b are gaseous. It is changed to quicklime by being pyrolyzed in the high tropics of 800 ° C. or higher in the mixing chamber b.

However, this thermal decomposition is a short-time solid-gas contact, and since the residual quicklime that cannot be completely combined with the chlorine in the exhaust gas is discharged as it is from the recovery port r, the moisture in the surrounding or atmosphere is It is dangerous because it reacts with and generates high heat.

The dioxins thermally decomposed almost completely in the gas mixing chamber b are then resynthesized between the reaction tower f and the bag filter h to become dioxins.
There are limits to taking dioxin measures using slaked lime alone.
For this reason, the method of taking out the collected ash into a separate device and heating it not only increases the heating cost, but also because the temperature is unstable and it is difficult to sufficiently heat all the collected ash, the removal rate of dioxins is low. On the contrary, there was a drawback that it became lower.

Further, as shown by a two-dot chain line in FIG. 6, after activated carbon t is supplied to the upstream side of the bag filter h to adsorb dioxins, the total amount of ash collected by the bag filter h is transferred to the gas mixing chamber b. When re-burning of unburned matter and pyrolysis of dioxins are performed, the problem of quick lime emission remains as described above, and unburned matter and incombustible matter are likely to be insufficiently separated. There is a disadvantage that the device becomes complicated if the problem (1) is addressed.

On the other hand, in the activated carbon adsorption method which is generally performed in addition to the above-mentioned respective methods, the activated carbon to which dioxins are adsorbed is directly discharged to the ash treatment device side, so that the amount of discharged ash increases and post-treatment cost increases. In addition to the problem that the ash is further increased, not only the burning loss is increased, but also the ash color becomes black, which may be confused with incomplete combustion.

[0017]

According to a first aspect of the present invention, there is provided a facility for treating exhaust gas, collected ash and the like, wherein the exhaust gas discharged from a refuse incinerator of general waste and industrial waste is supplied to a reburning chamber and It is led to the bag filter through the gas de-heating equipment, and the harmful gas neutralizing agent and the carbon-based adsorbent supplied to the bag filter are used to filter the soot and acid harmful gas and dioxins contained in the exhaust gas. Exhaust gas from a refuse incinerator, which is configured to be removed by summing and adsorbing, in a treatment facility for collecting ash, etc., is disposed in a hopper of the bag filter, and collects ash dropped from the bag filter. A classifier that roughly classifies unburned materials and incombustibles, an unburned material return device that returns unburned materials classified by the classifier to a reburning chamber, and stabilizes incombustible materials classified by the classifier. And a non-combustible ash treatment device

According to a second aspect of the present invention, there is provided a method for treating exhaust gas, collected ash and the like, wherein the exhaust gas discharged from a refuse incinerator is guided to a bag filter through a reburning chamber and a gas temperature reducing facility. The supplied harmful gas neutralizing agent and carbon-based adsorbent filter and neutralize, adsorb and remove the soot and soot harmful gases and dioxins contained in the exhaust gas. In the treatment method of ash and the like, the collected ash collected by the bag filter descended in a state of a high-temperature free powder in response to a removing operation, and adsorbed dioxins by a classification device provided in a hopper. Non-combustible substances such as carbon-based adsorbents and incombustible substances consisting of chemicals for neutralizing harmful gases and fly ash are returned.The unburned substances are returned to the reburning chamber and recombusted. Dies adsorbed on a sorbent The connexin compound is thermally decomposed while the incombustible is one that performs the stabilizing process is transferred to the non-combustible ash treatment apparatus.

According to a third aspect of the present invention, there is provided a method for treating exhaust gas, collected ash, or the like, wherein the bag filter uses a harmful gas neutralizing agent and a carbon-based adsorbent before starting the filtration operation. A precoat layer is formed on the filter cloth surface of the filter.

[0020]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an outline of a treatment facility for treating exhaust gas, collected ash and the like according to the present invention, and FIG. 2 is a sectional structural view showing an example of a classification device.

In FIG. 1, reference numeral 1 denotes a refuse incinerator for incinerating refuse such as general waste or industrial waste.
1 connects the waste incinerator 1 and the separately installed reburning chamber 2, and subsequently connects the gas deheater 3, the bag filter 4, and an unillustrated draft fan toward the chimney.

Here, the reburn chamber 2 is a reburn chamber main body 21 and a reburn burner which is provided above the reburn chamber main body 21 and heats and burns a combustion gas 51 from the refuse incinerator 1 and an unburned substance described later. 22, an unburnt ash supply mechanism 23 attached to the upper side wall of the reburn chamber main body 21, and a reburn ash discharge mechanism 24 provided at a lower portion of the reburn chamber main body 21.

The gas cooling device 3 includes a gas cooling device 31.
, The air preheater 32 and the other heat exchanger group 33 are mainly used to reduce the temperature of the reburning gas 52 flowing therethrough, and also to heat the normal-temperature air sent from the push-in blower 34 so that the refuse incinerator 1, This is a facility for supplying necessary parts such as the reburning chamber 2 and hot water supply / heating means (not shown).

The bag filter 4 includes a filtration chamber 42 for suspending a plurality of filter cloths 41, an inverted pyramid-shaped hopper chamber 43 mounted below the filtration chamber 42, and a filter chamber located above the filtration chamber 42. Clean gas chamber 45 provided with dropping means 44 (FIG. 2)
This is a facility in which a plurality of unit dust collection mechanisms (see FIG. 1 and FIG. 2, only one chamber is representatively shown), each of which includes a clean gas damper 46 provided on the outlet side of the clean gas chamber 45 and the like.

An exhaust gas duct 35 connected to the inlet side of the bag filter 4 has a chemical storage tank 62 for storing a neutralizing agent (neutralizing agent) 61 for neutralizing an acidic harmful gas such as slaked lime, for example. An adsorbent storage tank 64 for storing a carbon-based adsorbent 63 such as activated carbon or activated coke is connected to each other via a discharging means.

Each of the powders discharged from the chemical storage tank 62 and the adsorbent storage tank 64 is transported by a transport gas 55 from a blower 65 which branches and suctions a part of the clean gas 54 from a common clean gas duct 47. Exhaust gas duct 3
5.

At the lower end of the hopper chamber 43 of the bag filter 4, there is provided an air flow classifier 7 for roughly classifying incombustibles and unburnt substances, which will be described later.

As shown in FIG. 2, the classifying device 7 includes a classifying pipe 71 opened at an outlet 48, and a classifier 56 for feeding a classifying gas 56 from a blower 65 (see FIG. 1) into the lower part of the classifying pipe 71. One of them is a blowing section 72 having a plurality of blowing ports, an incombustible discharge means 73 attached to the lower end of the classification pipe 71, an unburned substance separation mechanism 74 attached to the upper end of the classification pipe 71, and an uncombusted discharge. It is constituted by means 75.

On the downstream side of the incombustible discharge means 73,
As shown in FIG. 1, an incombustible ash treatment device 76 is installed, and the uncombustible ash supply mechanism 23 is provided downstream of the uncombustible material discharging means 75 by a conveyor or a bucket elevator.
The unburned matter return mechanism 77 connected to the unburned matter return mechanism 77 and the unburned ash supply mechanism 23 constitute an unburned matter return device.

Next, a method of treating the exhaust gas, collected ash and the like by the thus configured exhaust gas and collected ash processing equipment will be described.

700 to 950 ° C. generated in refuse incinerator 1
The combustion gas 51, whose temperature is likely to fluctuate, is introduced into the reburning chamber 2, and becomes high in temperature of 850 ° C. or more by the addition of the reburning air 36 and the reburning by the flame of the reburning burner 22 in addition to its own heat. Under a high-temperature atmosphere, unburned carbons, which are precursors of dioxin generation, and unburned gas causing unpleasant odor, are completely burned.

At the same time, the dioxins contained therein are also thermally decomposed and then turned into a reburn gas 52 to be sent to the gas temperature reducing equipment 3.

At this time, in order to reverse the flow of the reburning gas 52 at the lower portion of the reburning chamber main body 21, the accompanying incombustible substances having a large specific gravity are separated from the reburning gas 52 by centrifugal force, and the reburning ash discharging mechanism 24 is provided. Thus, the waste is sent to the incineration ash discharge mechanism 12 and discharged to an incineration ash treatment device (not shown) together with the incineration ash discharged from the waste incinerator 1.

The reburning gas 52 from which the incombustibles and the like are separated
Is cooled by the gas temperature reducing equipment 3 to become exhaust gas 53 having a temperature of 200 ° C. or less, and passes through the exhaust gas duct 35 and enters the bag filter 4 composed of a plurality of unit dust collecting mechanisms.

On the other hand, the normal-temperature air sent into the air preheater 32 by the push blower 34 is supplied to the air preheater 32.
Heat exchange with the passing hot gas at 200 to 25
It becomes high-temperature air of 0 ° C. and is used for the combustion air 37 of the refuse incinerator 1 and the like in addition to the above-mentioned reburned air 36.

Here, as shown in FIG. 3, a primary adhesion layer 411 of slaked lime or the like is formed on the surface of the filter cloth 41 in the bag filter 4 in advance.

In this state, a neutralizing agent 61 such as slaked lime is fed from the agent storage tank 62 through the exhaust gas duct 35 by the transport gas 55 to form a drug layer 412 on the primary adhesion layer 411 (FIG. 3).

Subsequently, the carbon-based adsorbent 63 is similarly fed from the adsorbent storage tank 64 by air, and the adsorbent layer 41 is placed on the drug layer 412.
3 and a two-stage precoat layer in combination with the drug layer 412 (see FIG. 3).

After the pre-coat layer is formed in this manner, the bag filter 4 shifts to a filtering operation. The acidic harmful gas in the exhaust gas 53 introduced into the bag filter 4 is neutralized by the chemical layer 412, and The dioxins that cannot be completely decomposed by the thermal decomposition in the reburning chamber 2 or are regenerated in the gas temperature reducing equipment 3 are adsorbed by the adsorbent layer 413.

On the other hand, the soot and dust that continues to fly along with the exhaust gas 53 is filtered by the two-stage precoat layer and deposited on the surface of the adsorbent layer 413 to form a dust layer 414 (see FIG. 3). The clean gas 54 is discharged from the clean gas damper 46 to the clean gas duct 47.

The neutralization / adsorption / filtration operation by the precoat layer is continued, and if the pressure difference between the inside and outside of the filter cloth portion or the concentration of harmful gas in the clean gas 54 exceeds the specified value, the removing means 44 After the trapping ash 81 composed of the drug layer 412, the adsorbent layer 413, and the dust layer 414 attached to the surface of the primary adhesion layer 411 is removed, the same precoat layer 412 as described above is applied to the surface of the primary adhesion layer 411. Form 413 and return to the filtration operation described above.

The components of the collected ash 81 are a carbon-based adsorbent 63 inactivated by adsorbing heavy metals such as dioxins and mercury, an unburned substance 82 composed of a small amount of unburned matter, Non-combustible material 8 composed of calcium chloride, etc., which is a reaction product with harmful gas, slaked lime, etc., which are unreacted chemicals, and ash, etc.
3.

The collected ash 81 is scattered in the form of powder from the surface of the filter cloth 41 by the removing means 44, and passes through the classifying pipe through the hopper chamber 43 in a free state without being combined with each other due to the high temperature. Descent to 71.

Therefore, if the switching valve 57 is switched to the classification device 7 side, the classification gas 5 adjusted to an appropriate amount by the control valve 58
Numeral 6 is injected from the blowing section 72 into the classification pipe 71, and blows up the unburned material 82, which is a lightweight material, to the unburned material separation mechanism 74.

In the unburned matter separating mechanism 74, the collected exhaust gas 59 mainly composed of the transported classification gas 56 is passed through the exhaust gas duct 3.
5 and the unburned matter 82 separated from the collected exhaust gas 59 is dropped to the unburned matter discharge means 75 side.

At the point when the unburned matter 82 has accumulated to some extent,
It is confirmed by a temperature recording controller (not shown) that the combustion state of the incinerator 1 is stable.
5 is operated, and the accumulated unburned matter 82 is supplied in batches into the reburning chamber main body 21 by the unburned matter return device.

As described above, the inside of the main body 21 is 850 ° C.
Since the above high-temperature reburning atmosphere is maintained, the supplied unburned matter 82 is completely burned to become carbon dioxide gas, and the dioxins adsorbed by the carbon-based adsorbent 63 are thermally decomposed to form inorganic chlorine. It becomes gas or inorganic chlorine compound.

On the other hand, the relatively heavy incombustible material 83 descends through the classifying pipe 71 without being accompanied by the rise of the classifying gas 56, and is discharged from the noncombustible material discharging means 73 to the noncombustible ash treatment device 76, where the ash is solidified. And so on.

The outline of the operation procedure during this time will be described with reference to the flowchart of FIG. [Formation of Precoat Layer] First, the clean gas damper 46 of the unit dust collection mechanism that has finished the cleaning operation is opened, and the exhaust gas 53 indicated by a thick line flows from the exhaust gas duct 35 into the bag filter 4 (step S1). At the same time, the switching valve 57 is switched to the drug transport side (step S2), and the neutralizing agent 61 and the carbon-based adsorbent 63 are injected into the exhaust gas duct 35 by the transport gas 55 which is a part of the clean gas 54, Filter cloth 4
A pre-coat layer is formed on 1 (step S3).

When the formation of the precoat layer is completed, the blower 65
Is stopped (step S4). [Cleaning operation] Thereafter, the exhaust gas 53 is circulated through the bag filter (BF) 4 on which the pre-coat layer is formed. The gas becomes the gas 54 and is discharged to the clean gas duct 47 (step S5). [Washing-off operation] By continuing this series of cleaning operations, if the pressure difference between the inside and outside of the filter cloth or the concentration of harmful gas at the outlet exceeds a specified value (step S6), the clean gas damper 46 is closed and indicated by a thick line. The flow of the exhaust gas 53 is stopped (Step S7). Subsequently, if the collected ash 81 on the filter cloth 41 is removed by the removing means 44, the collected ash 81 indicated by a dotted line is obtained.
Is scattered in a powder form (step S8), and falls from the discharge port 48 to the classification pipe 71 via the hopper chamber 43 (step S9). [Classification operation] At the same time, the blower 65 is restarted to switch the switching valve 57 to the classification side (step S10), and the classification gas 56 is injected from the blowing unit 72 into the classification pipe 71 (step S11). Powdered ash 81 indicated by a dotted line
Are largely divided into a light unburned matter 82 and a heavy unburned matter 83 by the rising force of the classification gas 56 (step S12).

The unburned matter 82 is separated from the unburned matter separation mechanism 74.
(Step S13), and the collected exhaust gas 59 mainly composed of the classified gas 56 to which the unburned matter 82 has been sent by air is discharged to the common exhaust gas duct 35 side (Step S14), and separated by the separated powder. Certain unburned materials 82 are supplied to unburned material discharge means 75.
It is accumulated above (step S15).

On the other hand, the incombustible material 83 that has descended downward in the classification pipe 71 is deposited on the incombustible material discharge means 73 (step S16).

As described above, the classification of the collected ash 81 in the present invention is different from the prior art in which the collected ash once accumulated in the lower part of the hopper chamber is discharged to the outside by a dropping operation, and then classified again. Ash 8 that is liable to cause mutual bonding
As described above, since air classification is carried out in the state of a high-temperature powder as described above, unburned / incombustible substances can be roughly classified by a simple device.

When the above classification operation is completed, the operation returns to the initial precoat operation (step A). [Processing operation] The non-combustible material 83 deposited on the above-described non-combustible material discharging means 73 is discharged to a non-combustible ash processing device 76 at an appropriate time.
Stabilization processing such as ash solidification is performed (step S17).

If the combustion state in the refuse incinerator 1 is stable (step S18), the unburned matter 82 deposited on the unburned matter discharge means 75 is discharged to the unburned matter discharge means 75. By driving, the unburned material 82 that has been accumulated is returned to the unburned material return mechanism 77.
And returned to the reburning chamber main body 21 via the unburned ash supply mechanism 23 (step S19), and the unburned matter 8
2 is completely burned, and the dioxins adsorbed on the carbon-based adsorbent 63 are thermally decomposed (step S20).

The shapes and arrangements of the waste incinerator 1, the reburning chamber 2, and the gas cooling equipment 3 are not limited to the contents of the present invention, and the precoat layer is composed of the chemical layer 412 and the adsorbent layer 4.
13, a mixed system in which a precoat layer is formed with the neutralizing agent 61 and then the carbon-based adsorbent 63 accompanies the exhaust gas 53 during the cleaning operation as shown in FIG. Although not shown, a mixed precoat layer forming method of forming a precoat layer in a state where the neutralizing agent 61 and the carbon-based adsorbent 63 are mixed may be used.

Further, a clean gas 54 is used for chemical injection and classification.
Was used, but hot air from the air preheater 32 may be used.

Further, the classification device 7 has been described as a system in which the classification gas 56 is blown into the classification tube 71 to perform wind separation, but other methods such as utilization of Coanda effect or utilization of centrifugal force may be employed. Shows a cyclone type, but a baffle plate sedimentation type or the like may be adopted.

[0060]

As described above, according to the present invention, each chemical and fly ash collected and removed by a bag filter precoated with a neutralizing chemical and a carbon-based adsorbent are subjected to high temperature. Since it is a method of roughly classifying into unburned matter and incombustible matter by a classifier in the state of the scattered particles, simple equipment is sufficient, and only the classified unburned matter is returned to the reburning chamber by the unburned matter return device. To complete combustion and the thermal decomposition of the dioxins adsorbed on the carbon-based adsorbent, so that the combustion is complete and the detoxification of the dioxins can be reliably performed.

Further, since the non-combustibles are re-burned and only the non-combustibles are stabilized by the non-combustible ash treatment device, the amount of ash discharged as specially controlled waste is reduced, and post-processing costs are reduced. Can be saved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an outline of a processing facility for treating exhaust gas, collected ash, and the like according to the present invention.

FIG. 2 is a sectional structural view showing an example of a classifying device.

FIG. 3 is a cross-sectional view showing a state of deposition on the surface of a filter cloth.

FIG. 4 is a cross-sectional view showing another deposition state of the filter cloth surface.

FIG. 5 is a flowchart showing an outline of an operation procedure.

FIG. 6 is a schematic diagram showing a configuration of a conventional refuse incineration facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Garbage incinerator 2 Reburning chamber 3 Gas de-heating equipment 4 Bag filter 41 Filter cloth 43 Hopper chamber 61 Chemicals for neutralizing harmful gases 63 Carbonaceous adsorbent 7 Classification device 76 Non-combustible ash treatment device 77 Unburned ash return mechanism

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 53 / 70,53 / 68,53 / 50 B01D 46 / 02,46 / 42 B09B 5/00

Claims (3)

(57) [Claims] 1. An exhaust gas discharged from a refuse incinerator, such as a general waste or an industrial waste, is guided to a bag filter through a reburning chamber and a gas temperature reduction facility, and is used for neutralizing harmful gas supplied to the bag filter. Chemicals and carbon-based adsorbents are used to filter, neutralize, adsorb and remove soot and soot harmful gases and dioxins contained in flue gas. In the treatment equipment, a classification device is provided in a hopper portion of the bag filter, and classifies the collected ash dropped from the bag filter into unburned matter and incombustible matter. A treatment facility for exhaust gas, collected ash, etc., comprising: an unburned matter return device for returning the burned material to the reburning chamber; and an incombustible ash treatment device for stabilizing the incombustible material classified by the classification device. . 2. Exhaust gas discharged from a refuse incinerator is led to a bag filter through a reburning chamber and a gas de-heating device, and a harmful gas neutralizing agent and a carbon-based adsorbent supplied to the bag filter are used. In a method of treating exhaust gas, ash, etc. of a refuse incinerator for filtering, neutralizing and adsorbing soot and harmful gas and dioxins contained in the exhaust gas, the collection by the bag filter The ash falls in the form of high-temperature free powder following the wiping-off operation, and is classified by a classifier provided in the hopper section to neutralize unburned substances such as carbon-based adsorbents adsorbing dioxins and harmful gases. Each chemical and non-combustible substances consisting of fly ash, etc. are roughly divided, and the unburned substances are returned to the reburning chamber and recombusted to thermally decompose dioxins adsorbed by the carbon-based adsorbent, while Items are non-combustible ash treatment equipment Exhaust gas, characterized in that the transfer has been Hodokosuru stabilization processing, processing methods such as collecting ash. 3. The bag filter according to claim 1, wherein a pre-coat layer is formed on the surface of the filter cloth of the bag filter using a harmful gas neutralizing agent and a carbon-based adsorbent before starting the filtering operation. Item 3. A method for treating exhaust gas, collected ash, and the like according to Item 2.