JP2003114019A - Device of reducing genus of dioxin for discontinuous combustion type refuse incineration facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce, by a simple facility, the exhaust quantity of genera of the dioxin generated mainly in starting and finishing operation in a discontinuous combustion type refuse incineration facility. SOLUTION: In the discontinuous combustion type refuse incineration facility which is constituted such that after re-combusting the exhaust gas introduced from an incinerator 1 into a re-combustion chamber 2, the exhaust gas is introduced into a dust cleaner through a gas temperature reducing equipment comprising an air preheater 31 for high temperature and a heat exchanger group 32 and a gas cooling chamber 33 to be purified, the dust cleaner comprises two groups, i.e., a bag filter 4 used in normal operation and an auxiliary bag filter 5 used in starting, finishing and normal operation, and auxiliary collected ashes 93 shaken down from the auxiliary gas filter in starting and finishing operation are returned to the re-combustion chamber 2 for pyrolyzing genera of the dioxin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reducing dioxins contained in exhaust gas and collected ash in a refuse incineration facility for incinerating refuse such as general waste and industrial waste.

[0002]

2. Description of the Related Art Exhaust gas discharged from a refuse incineration facility contains dioxin, which is a toxic substance, in addition to soot and acidic harmful gas. Dioxin is also contained in the collected ash of dust collection equipment. include.

The Ministry of Health and Welfare has established guidelines for controlling the emission of these dioxins, and in the incinerator, the combustion is stabilized based on the fully continuous combustion system, and the combustion gas can stay at 850 ° C or higher for 2 seconds. In addition to providing a reburning chamber, a bag filter with high dioxin removal capacity is used for the exhaust gas treatment facility, and a burning method that does not leave unburned materials in the incinerator during a decommissioning is recommended.

Further, the ash collected by the bag filter is required to be stabilized as a specially controlled waste.

The above guideline can be complied with in the case of a fully continuous combustion type incinerator, which has a large processing capacity and stable combustion, but the amount of waste and the number of personnel are small, and the operation is limited to about 8 hours a day. There are many drawbacks in the case of mechanized batch furnaces, which cannot be used, and quasi-continuous combustion type incinerators, which can operate for 16 hours. In particular, as a result of adopting the above-mentioned burning method, the furnace temperature in the next morning is reduced to 150 to 300 ° C, and the bag filter inlet temperature is reduced to 80 to 150 ° C. There are problems such as low temperature corrosion of the above equipment and sticking of a highly deliquescent neutralizing chemical reaction product to the filter cloth.

Therefore, in the mechanized batch furnace and the quasi-continuous combustion type waste incinerator, that is, the discontinuous combustion type incinerator in which the furnace is shut down for a predetermined time every day, the temperature inside the incinerator rises and the bag filter inflow gas temperature rises to 130 ° C. During the start-up work until reaching a certain level and after the burning work in which the heat source is lost, the bag filter is bypassed and exhaust gas is allowed to flow to prevent low-temperature corrosion of the bag filter and adhesion of reaction products to the filter cloth. The method has been adopted, which has led to the situation of releasing soot and dioxins for a long time.

As a measure against bypass during the startup work,
A "bag filter for incinerator" whose outline is shown in FIG. 6 is disclosed in Japanese Patent Laid-Open No. 6-79118.

That is, by providing a bag filter that does not spray slaked lime or a low temperature filter LTF using an electric dust collector on the normal bypass flue BPL, the soot and dust in the exhaust gas at low temperature is trapped. During normal operation, the main bag filter MBF is switched by the switching valve COV.
This is a method in which normal filtration and neutralization work is performed by passing the gas through.

Although these bypass flue gas treatment methods are effective as a countermeasure against bag filter damage due to low-temperature gas at the time of starting and shutting down a non-continuous combustion type refuse incinerator, they are effective in reducing dioxins for the purpose of the present application. Is a technology that is not available.

Therefore, as a typical example of an exhaust gas treatment method for removing dioxins, Japanese Patent Application Laid-Open No. 8-243341 is used.
FIG. 7 shows a process diagram of exhaust gas treatment disclosed in Japanese Patent Publication No.

In FIG. 7, the exhaust gas from the incinerator a is
The temperature is reduced to about 150 ° C. by the temperature reducing device b, and dust is removed by dust removing equipment c such as a bag filter or an electric dust collector.

Subsequently, a fresh adsorbent e made of activated carbon, slaked lime, etc. supplied from the adsorbent addition device d is added to the gas after the primary dust removal, and the dust is cleaned again by the subsequent bag filter f. After that, it is released from the chimney g into the atmosphere.

The dust h collected here by the dust removal equipment c
Is treated in the ash treatment facility i, and the collected ash j mainly containing the adsorbent collected in the bag filter f is regenerated by the desorption / regeneration facility k by heating it to 400 ° C. or higher in a reducing atmosphere. The regenerated adsorbent m is added to the upstream side of the bag filter f.

There is also a method in which a part or the whole amount of the collected ash j is recirculated to the upstream side of the dust removal equipment c as shown by the chain double-dashed line, both of which have the effect of reducing the consumption of the fresh adsorbent e. is there.

Further, the exhaust gas generated from the desorption / regeneration facility k is treated in the heavy metal treatment facility n.

[0016]

However, the above conventional exhaust gas treatment system requires double dust removal equipment, desorption / regeneration equipment k for collected ash and heavy metal treatment equipment n.
However, there is a problem that the equipment cost and the operating cost are complicated due to complexity.

Further, in the case of a general device arrangement in which a water injection type gas cooling chamber is placed in front and an air preheater and an air heater for preventing white smoke are placed after the air preheater and air for preventing white smoke. Exhaust gas passing through the inside of the heater, etc.
Since the temperature is gradually lowered to around 70 ° C., it meets the temperature conditions for re-synthesizing dioxins, and a high concentration of dioxins arrives at the dust removal equipment.

Further, the bypass system shown in FIG. 6 has no countermeasure against dioxin, and in the case of the conventional technique shown in FIG. 7, no bypass circuit is provided for the full continuous combustion system. On the other hand, in the case of the non-continuous combustion method, as described above, since all the equipment including the inside of the incinerator is destined to cool when it is shut down, organic chlorine compounds generated in the incinerator during the initial startup and shutdown However, no consideration is given to the phenomenon of being resynthesized in a low temperature range to generate a high concentration of dioxin.

Therefore, in particular, a large amount of dioxins are adsorbed by the bag filter of the dust removal equipment c and discharged not only to the ash treatment equipment i having no dioxin treatment capability, but also at the time of start-up / down. Due to the easy low temperature corrosion and the deliquescent phenomenon on the surface of the filter cloth, there has been a problem that the maintenance cost of the dust removal equipment c and the post bag filter f as a whole increases.

[0020]

A dioxin reduction apparatus for a discontinuous combustion type refuse incineration facility according to the invention of claim 1 is
When incinerating waste such as general waste and industrial waste, exhaust gas discharged from a discontinuous combustion type waste incinerator that is decommissioned for a predetermined time every day is guided to a bag filter through a reburn chamber and a gas temperature reduction facility. , Configured to filter, neutralize, adsorb and remove soot and dust, acidic harmful gas and dioxins contained in exhaust gas by a chemical for neutralizing harmful gas and a carbon-based adsorbent supplied to the bag filter In the discontinuous combustion type waste incineration facility, the bag filter is a sub-bag filter that is used during startup / shutdown and during normal operation, and a main bag filter for normal operation that has a larger capacity than the sub-bag filter. And a discharge means for discharging the collected ash of the sub bag filter is connected to the reburn chamber via the switching means and the collected ash transfer mechanism.

In the dioxin-reducing device of the discontinuous combustion type refuse incineration facility of the invention according to claim 2, the gas temperature reducing facility is a heat exchanger such as an air preheater for high temperature and an air heater for preventing white smoke. The group is placed in front, and the water injection type gas cooling chamber is placed in back.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION 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 dioxin reduction device of a discontinuous combustion type refuse incineration facility according to the present invention, and FIG. 2 is a diagram showing gas, air, fly ash and water of the incineration facility. FIG. 6 is a schematic flow chart mainly showing the flow of FIG.

In FIGS. 1 and 2, reference numeral 1 denotes an incinerator for incinerating refuse such as general waste and industrial waste, and a reburn chamber 2 installed on the incinerator 1 has a downstream gas reduction unit. The main bag filter 4 and the sub bag filter 5 are passed through the heating equipment 3
It is connected to a mixing flue, an induced draft fan, and a chimney (not shown) through the dust removal equipment composed of a group.

The incinerator 1 comprises a vertical incinerator body 11
A hopper 12 for supplying garbage, a dry grate 13,
A dust support means 14 for supporting dust being burned at the bottom of the incinerator body 11, an incineration ash discharging means 15 located below the dust support means 14, and a start-up / burning auxiliary burner 16
And the furnace outlet 17 and the furnace outlet 1 which are the connection ports with the reburn chamber 2.
It is composed of a furnace thermometer 18 (see FIG. 2) and the like provided in the vicinity of 7.

The reburn chamber 2 is provided above the furnace outlet 17 and is a device for reburning the combustion gas 61 discharged from the incinerator 1 and the ash collected by the sub bag filter 5 described later. The main body 21, the mixing plate 22 provided above the furnace outlet 17, the supply mechanism 23 for the collected ash attached to the upper part of the reburn chamber main body 21, and the reburn burner 2 for raising the temperature of the reburn chamber.
4 and an elevated flue 25 connected to the outlet of the reburn chamber body 21.
And a reburn chamber thermometer 26 (see FIG. 2) and the like.

The gas temperature reducing equipment 3 includes a heat exchanger group 3 such as a high temperature air preheater 31 and a white smoke preventing air heater which are placed in front of the gas heat reducing equipment 3.
2 and a water injection type gas cooling chamber 33 to be installed later are connected mainly.

Since the air preheater 31 and the heat exchanger group 32 exchange heat with the high temperature reburned gas 62, the heat transfer tube surface is coated with an amorphous refractory material such as silicon carbide or high alumina type heat resistance. The re-burning gas 62 flowing through is reduced in temperature to form the temperature-decreasing gas 63, and the insufficient amount of reduced temperature is entrusted to the subsequent gas cooling chamber 33.

On the other hand, as shown in FIG.
The room-temperature air sent from the air preheater 31 to the incinerator 1 is heated to supply the combustion air 35 to the incinerator 1 and the reburning air 36 to the reburning chamber 2, and a heat exchanger from another blower (not shown). The room-temperature air sent to the group 32 is also used for raising the temperature of the clean gas (not shown) and utilizing the residual heat for heating and hot water supply.

The gas cooling chamber 33 is a device for reducing the temperature of the temperature-falling gas 63 that has exited from the heat exchanger group 32 to a temperature that maximizes the removal efficiency of the main bag filter 4 that follows, and a plurality of upstream cooling units. The direct pressure type water injection nozzle 37 and the two-fluid water injection nozzle 38 are provided on the downstream side.

The main bag filter 4 has a filter chamber 42 for suspending a plurality of filter cloths 41, a hopper chamber 44 provided with a discharging means 43 mounted below the filter chamber 42, and a filter chamber 42 above the filter chamber 42. Clean gas chamber 46 having means 45 for removing
It is composed of a plurality of unit dust collecting mechanisms (FIG. 1 exemplifies three chambers).

The sub bag filter 5 has a structure similar to that of the main bag filter 4, that is, a filtration chamber 52 for suspending a plurality of filter cloths 51, a hopper chamber 54 having a discharging means 53, and a discharging means 55. And a clean gas chamber 56 and the like, and usually one section of a bag filter device in which a plurality of unit dust collecting mechanisms are assembled is used as a sub bag filter.

The main bag filter 4 and the sub bag filter 5 thus constructed are connected to the flue base portion 73 disposed at the outlet of the gas cooling chamber 33 through the flue and clean duct group. ing.

The above-mentioned flue and clean duct group are the main flue 7
4, secondary flue 76, bypass flue 78, main cleaning duct 75
And a sub-cleaning duct 77.

The main flue 74 is connected to the flue base 73 and has a main exhaust gas damper 74d for introducing the exhaust gas 64 into the main bag filter 4 during normal operation.

The auxiliary flue 76 is branched from the main flue 74, and is provided with an auxiliary exhaust gas damper 76d to introduce the medium temperature exhaust gas 66 to the auxiliary bag filter 5 at the time of starting and lowering operations.

The bypass flue 78 is communicated from the flue base 73 to the main cleaning duct 75, and is provided with a bypass damper 78d for supplying the low temperature gas 68 at the time of starting and after burning.
The flue base 73 is discharged directly to the main cleaning duct 75.

The main cleaning duct 75 has a main cleaning gas damper 75d and discharges the cleaning gas 65 from the main bag filter 4 during normal operation.

The sub-cleaning duct 77 is provided with a sub-cleaning gas damper 77d, and discharges the intermediate-temperature cleansing gas 67 from the sub-bag filter 5 to the main cleaning duct 75 at the time of starting and lowering operations.

The branch point of the bypass flue 78 and the auxiliary flue 7
One end of a pipe 81 for drug transportation is connected to the main flue 74, which is the middle of the branch point of No. 6, and a chemical 82 for neutralizing an acidic harmful gas such as slaked lime 82 is provided in the middle of the pipe 81.
The chemical storage tank 83 for storing the carbon dioxide and the adsorbent storage tank 85 for storing the carbon-based adsorbent 84 such as powdered activated carbon or activated coke are connected to each other via the discharge means.

Each powder discharged from the medicine storage tank 83 and the adsorbent storage tank 85 is sent under pressure into the main flue 74 by the transfer air 69 from the medicine blower 86 for sucking air at room temperature. A drug layer is formed on the surfaces of the filter cloths 41 and 51 of the bag filter 4 and the sub bag filter 5.

A common discharge conveyor 47 is provided below the plurality of discharge means 43 of the main bag filter 4, and neutralizes ash collected by the main bag filter 4 during normal operation and acidic harmful gas. The main fly ash 91 from which the above-mentioned drug layer having adsorbed dioxins has been removed is discharged to a fly ash treatment device 92 for stabilization treatment.

A switching means 57 is provided below the discharging means 53 of the sub bag filter 5, and this switching means 57 is provided.
Collects the sub-collection ash 93 from which the sub-bag filter 5 collects the ash collected by the sub-bag filter 5 during the start-up / shutdown operation and the drug layer which adsorbs dioxins and neutralizes the acidic harmful gas. While being returned to the reburn chamber main body 21 via the ash collection transfer mechanism 58 and the supply mechanism 23, it is switchable so as to send the auxiliary fly ash 94, which has been removed in the same manner as the main bag filter 4 during normal operation, to the discharge conveyor 47. It is configured.

Next, the treatment of the exhaust gas from the initial startup to the final shutdown in the discontinuous combustion type refuse incinerator thus constructed will be described.

The temperature inside the incinerator body 11 at the start of the work is 15
Since the temperature has dropped to 0 to 300 ° C, the burner burner 16
Thus, the temperature inside the incinerator body 11 where only the incineration ash remains is raised to the dust ignition temperature.

Next, the combustible waste for start-up, which has been sorted in advance in a waste storage site (not shown), is supplied little by little from the hopper 12 onto the dry grate 13 and burned to burn the waste. Combustion gas generated by heating the inside 6
1 is sent to the reburn chamber 2 through the furnace outlet 17, and the incinerated ash is discharged from the incinerated ash discharging means 15 to the outside of the furnace in a timely manner through the dust support plate 14.

In the reburn chamber 2, the high temperature reburn air 36 supplied and the flame of the reburn burner 24 heat the combustion gas 61 stirred and mixed by the mixing plate 22 to 850 ° C. or higher.
Under the high temperature atmosphere, unburned carbons, which are precursors for dioxins generation, and unburned gas that causes a bad smell are completely burned.

Dioxins contained at the same time are also thermally decomposed into reburned gas 62, and by raising the temperature of the air preheater 31 and the heat exchanger group 32 from the elevated flue 25, the reburned gas 62 is reburned by the dioxin. The temperature is lowered to a temperature at which it is not synthesized, and becomes the temperature-falling gas 63. After passing through the gas cooling chamber 33, it is further lowered in temperature at once to become the low-temperature gas 68. From the flue base 73 through the bypass flue 78 to the main cleaning duct 75.
Sent to.

At this time, the temperature of the low temperature gas 68 is measured by a flue thermometer 79 (see FIG. 2) provided in the flue base 73, and the main / sub bag filters 4 due to low temperature corrosion and deliquescence,
If the temperature is 130 ° C or higher, which can avoid the adverse effect on 5,
The gas passage is switched from the bypass flue 78 to the auxiliary flue 76, and the heated intermediate temperature exhaust gas 66 is passed to the auxiliary bag filter 5.

On the surface of the filter cloth 51 of the sub bag filter 5, a precoat layer of a sufficient thickness is formed in advance by the neutralizing agent 82 and the carbon-based adsorbent 84, and is contained in the medium temperature exhaust gas 66. The soot and dust, the acidic harmful gas, and the small amount of dioxins resynthesized after the thermal decomposition are filtered, neutralized, and adsorbed by the precoat layer to become the intermediate-temperature clean gas 67, and the main clean is passed through the sub-cleaning duct 77. It is discharged to the duct 75.

The temperature of the reburned gas 62 in this state is
Reburning chamber thermometer 2 provided near the outlet of the reburning chamber body 21
If it is confirmed to be stable at 850 ° C or higher as confirmed in step 6, switch to normal operation with general waste.

At the time of switching, first, the precoat layer and the collected ash on the surface of the filter cloth 51 of the sub bag filter 5 are removed by the means 55.
The sub-collection ash 93, which has been removed by means of the above, is retained on the collection ash transfer mechanism 58 through the discharging means 53 and the switching means 57, and a precoat layer of normal thickness is provided on the surface of the filter cloth 51. Reform.

If the combustion state in the incinerator 1 is stable as a result of the measurement by the in-furnace thermometer 18, the retained sub-collection ash 93 is collected by the collection ash transfer mechanism 58 and the supply mechanism 23. It is sent to the reburn chamber 2 and reburned.

In normal operation, the amount of the exhaust gas 64 is increased by incinerating the rated amount of general waste.
Following the main bag filter 4, the sub bag filter 5 in which the above-mentioned precoat layer is re-formed is involved in the operation.

At this time, since the main bag filter 4 has a precoat layer formed in advance as in the case of the sub bag filter 5 described above, the exhaust gas 64 is filtered, neutralized, and filtered by the main and sub bag filters 4 and 5. Adsorbed into clean gas 65,
From the main and sub cleaning ducts 75 and 77, it is discharged into the atmosphere from the chimney through an unillustrated draft fan.

When this normal operation is continued and a detector group (not shown) causes the internal and external differential pressures of the filter cloths 41 and 51 or the harmful gas concentration in the clean gas 65 to exceed the specified value, the removing means 45, After removing the precoat layer and the collected ash on the surface of each filter cloth by 55, the precoat layer is re-formed on the surface of each filter cloth by the neutralizing agent 82 and the carbon-based adsorbent 84, and the normal filtration operation is performed. Return.

During this normal operation, the combustion state of the incinerator 1 is relatively stable, and the thermal decomposition of the dioxins and their precursors in the incinerator 1 and the reburn chamber 2 is completely performed (toxicity of dioxins). Equivalent: hereinafter abbreviated as DXQ = about 1 ng
-TEQ / Nm ³ ) and the temperature of the temperature-falling gas 63 at the outlet of the heat exchanger group 32 is 550 to 650 ° C. where there is no risk of re-synthesis of dioxins, and then the gas cooling chamber 3
Exhaust gas 64
Almost all dioxins in the inside can be prevented (DXQ <2
ng-TEQ / Nm ³ ), DXQ <0.1 ng-T in the clean gas 65 due to adsorption by the main / sub bag filters 4 and 5.
Achieving EQ / Nm ³ becomes easy.

Therefore, the main fly ash 91 blown off from the main bag filter 4 and the sub fly ash 94 blown off from the sub bag filter 5 during normal operation are 1/10 to 1/5 of the conventional system.
Since only a small amount of dioxins is contained, not only the supply amount of the carbon-based adsorbent 84 can be small, but also the stabilization process in the fly ash processing apparatus 92 becomes easy.

However, the sub-collection ash 93 discharged from the sub-bag filter 5 at the time of start-up and shut-down is obtained by treating the exhaust gas at a time when the incinerator as a whole is at a relatively low temperature and is unstable, and the reburn chamber 2 Even if thermal decomposition is performed in the interior, there is a great possibility that dioxins are resynthesized in the gas temperature reduction facility 3 and adsorbed in the sub-collection ash 93.

Therefore, the sub-collection ash 93 containing the carbon-based adsorbent 84 that has adsorbed dioxins on the surface of the filter cloth 51 is returned to the reburn chamber 2 when the combustion state is stable during normal operation, and the dioxins are thermally decomposed. And the carbon-based adsorbent 84,
The amount of fly ash in the exhaust gas 64 is reduced by burning the unburned matter in the collected ash.

Here, the cooling of the temperature-falling gas 63 in the gas cooling chamber 33 from the latter stage of the start-up process to the normal operation is performed by the direct pressure type water injection nozzle 37 on the upstream side and the two-fluid type water injection nozzle 38 on the downstream side. Since the complete evaporation type automatic control is performed by the cooperation of the above, the non-evaporated water does not flow into the dust removing device side and the processing performance and the like are not impaired.

When such a normal operation is performed and a predetermined amount of waste incineration work is completed, the supply of waste is stopped and the burner burner 1 is operated.
6 is ignited, and the burning operation is performed until the dust on the dry grate 13 and the dust supporting means 14 is completely ashed.

As a result, when the flame combustion due to the volatile components in the waste is finished and the fixed carbon is switched to the alternate combustion, the sub bag filter 5 is switched to the independent operation to filter the residual gas.
Neutralize and adsorb.

After that, when the amount of residual gas generated becomes small and the temperature of the flue base 73 becomes lower than the specified value, the bypass operation is switched to the idling state in order to avoid low temperature corrosion and deliquescence.

An outline of the operation procedure during this period is shown in FIGS.
This will be described with reference to the flowchart in FIG.

FIG. 3 is a chart showing the temperature rising and starting steps, FIG. 4 is a normal operation step, and FIG. 5 is a chart showing the falling step.
The displayed temperature shows a standard value. [Temperature raising step] First, at the start of operation, since the temperature of all the facilities including the inside of the incinerator body 11 is lowered, the auxiliary burner 16 and the reburning burner 24 are ignited, and the inside of the incinerator 1 and the reburn chamber 2 By raising the temperature of all the equipment that has been in bypass operation from the day before (step S ₁ ), the burner heating is continued until the measured value of the in-furnace thermometer 18 exceeds 400 ° C. (step S ₁ ). ₂ ). [Start-up process] When the temperature in the incinerator 1 reaches 400 ° C or higher, if combustible waste for start-up is supplied little by little, the waste is immediately ignited and begins to burn in the incinerator 1. ,
While heating the inside of the incinerator body 11 and accelerating the temperature rise of the reburn chamber 2 and the gas temperature reducing equipment 3 (step S ₃ ), a large amount of material is synthesized on the surface of the filter cloth 51 of the sub bag filter 5 at low temperature. A precoat layer is formed by using the carbon-based adsorbent 84 increased in amount to deal with dioxins and the normal amount of the neutralizing agent 82 (step S ₄ ).

As a result of the above temperature raising work, when the temperature of the flue base 73, which has been lowered to 100 ° C. or less, that is, the inlet temperature of the sub bag filter 5 exceeds 130 ° C. at which gas can pass (step S ₅ ), The sub exhaust gas damper 76d and the sub clean gas damper 77d are opened and the bypass damper 78d is closed,
Gas is passed from the auxiliary flue 76 to the auxiliary bag filter 5, and the precoat layer filters, neutralizes, and adsorbs the intermediate temperature exhaust gas 66 at startup to form the intermediate temperature clean gas 67.
It is discharged to No. 7 (step S ₆ ).

In this state, gradually increase the amount of startup waste supplied
Increase (Step S₇), The reburn chamber that was initially volatile
Continue until the outlet temperature continues to be above 850 ° C (step
S ₈).

At this point, the dust generated by the startup waste is burned.
Ioxins and unburned substances are completely pyrolyzed to reduce gas temperature
Mid-temperature exhaust gas 66 after dehumidifying at facility 3 is transferred to sub bag filter 5
Therefore, it is in the state of purification, the start-up operation is completed,
Then, the operation proceeds to the normal operation step 4 (step A). [Normal operation process] First, the inside of the heated incinerator body 11 is
Put a certain amount of general garbage into each (Step S ₉), Burning is cheap
If set, stop the auxiliary burner 16 and the reburn burner 24.
Stop (Step S_Ten). The auxiliary burner 16 and
If the combustion becomes unstable in the middle, the burner 24 will fire at the appropriate time.
To do.

Since the amount of refuse supply increases and the amounts of combustion gas 61 and exhaust gas 64 also increase, the main exhaust gas damper 74d
And the main clean gas damper 75d are opened, and the auxiliary exhaust gas damper 7
By closing the 6d and secondary cleaning gas damper 77d, from the secondary bag filter 5 switches the driving system in the main bag filter 4 (step S _11), enters the normal operation while the precoat layer formation (step S _12).

The sub bag filter 5 system in which the passage of gas has been stopped (step S ₁₃ ), the precoat layer and the collected ash adhering to the surface of the filter cloth 51 are removed (step S ₁₄ ), and the discharging means 53 and the switching means. It is retained on the collected ash transfer mechanism 58 via 57 (step S ₁₅ ), and a precoat layer is formed on the surface of the filter cloth 51 by the neutralizing agent 82 and the carbon-based adsorbent 84 (step S ₁₆ ). After that, the secondary exhaust gas damper 76d
And the sub-cleaning gas damper 77d are opened to start parallel operation with the main bag filter 4.

Sub-collection ash 9 retained in step S ₁₅
No. 3 confirmed that the combustion state in the incinerator 1 exceeded 850 ° C. and was stable (step S ₁₇ ), and was returned to the inside of the reburn chamber main body 21 by the ash collection transfer mechanism 58 and the supply mechanism 23. , And is rendered harmless by being reburned together with the combustion gas 61 (step S ₁₈ ).

On the other hand, in step S ₁₂ , the four main bag filter systems that have entered the normal operating state due to the combustion of a predetermined amount of dust are
If the removal condition is reached by continuing the operation, after removing the precoat layer and the collected ash on the surface of the filter cloth 41, the precoat layer is formed again, and the exhaust gas 64 is filtered, neutralized and adsorbed (step). S ₁₉ ).

Here, the precoat layer and the collected ash that have been blown off become the main fly ash 91, and fly from the discharge conveyor 47 together with the sub fly ash 94 that was blown off from the sub bag filter 5 that entered the parallel operation. It is sent to the ash processing device 92 and stabilized (step S ₂₀ ).

The above incineration-filtration / neutralization / adsorption-discharging-
By repeating a series of steps of the precoat layer forming, end normal operation has finished waste incineration operations a predetermined amount (step S _21), moves to the fall process of FIG. 5 (step B). [Fall point Step] First, the supply of the waste after the waste layer thickness on the drying grate 13 and refuse supporting means 14 is operated to be thinner stopped (step S _22), and ignite the auxiliary burner 16, incinerated waste in the furnace 1 performs operation Ri baked make every焚切until the ashes (step S _23).

As a result, if the flame in the furnace due to the combustion of volatile components in the waste disappears (step S ₂₄ ), it is judged that the combustion has shifted from flame combustion to combustion, and the auxiliary burner 1
6 extinguished (step S _25), closes the main exhaust gas damper 74d and the main cleaning gas damper 75d, the main bag filter 4
To pause the system, the operation of the sub bag filter 5 strains only (step S _26).

The main bag filter 4 whose gas flow is stopped is
The ash collected during normal operation and the precoat layer are removed (step S ₂₇ ), and the main fly ash 91 is stabilized (step S ₂₈ ).

In the sub-bag filter 5 system that has been operated independently in step S _{26, the} medium temperature exhaust gas 66 is continuously filtered, neutralized and adsorbed by combustion every time the temperature is reduced and the temperature is lowered (step S ₂₉ ). When the temperature falls below 130 ° C. (step S ₃₀ ), the bypass damper 78 d is opened and the auxiliary exhaust gas damper 76 d and the auxiliary clean gas damper 77 d are stopped to switch to the bypass operation (step S ₃₁ ). Prevent adverse effects on dust removal equipment.

After that, the precoat layer and the collected ash of the sub bag filter 5 in which the content of dioxins is increased due to the treatment of the medium-temperature exhaust gas 66 is removed to form the sub collected ash 93, and the collected ash transfer mechanism. Switching means 57 switched to the 58 side
After that, it is stored on the collected ash transfer mechanism 58 (step S ₃₂ ), and all the operations are completed.

Incidentally, the incinerator 1 and the reburn chamber 2 in the present description.
The shape of the gas temperature reducing equipment 3 is not limited to the shape shown in FIG.
Although one damper is provided on each of the flue side and the cleaning duct side, one may be omitted.

Although the method of forming the chemical layer has been described as the precoat method, the exhaust gas entrainment method may be adopted during the normal operation, and the removing operation in steps S ₂₇ and S ₃₂ in FIG. Although not limited to the end time, it may be performed before the next day's gas passage, and the ambient air is sucked as the transfer air 69 of each medicine, but a part of the clean gas 65 may be sucked in a branched manner.

[0082]

As described above, according to the present invention, the sub bag filter is used only when the amount of dioxins produced is large, and the main and sub bag filters are used together when the amount of dioxins produced is small. Therefore, the equipment cost can be reduced as compared with the conventional two-stage configuration.

Further, the sub-collection ash having a high content of dioxins is thermally decomposed in the reburn chamber, and the fly ash treatment device processes only the fly ash during normal operation having a low content of dioxins. In addition, not only is the equipment simplified, but there is no need to separately install desorption / regeneration equipment for collected ash or heavy metal processing equipment.

Further, the sub-collection ash of the sub-bag filter at the time of start-up / shutdown, which has a high risk of dioxins generation, is not only thermally decomposed in the reburn chamber but also reduced in gas only when combustion in the incinerator is stable. Danger of re-synthesis of dioxins by installing a heat exchanger group such as an air preheater for high temperature and an air heater for white smoke prevention in front of the heating equipment and a water injection type gas cooling room after Since the arrangement avoids the temperature range, the content of dioxins at the entrance of the dust removal device is significantly reduced, and the emission of dioxins can be reduced by using a small amount of carbon-based adsorbent.

Further, the damage of the bag filter due to the adsorption treatment of high-concentration dioxins and the low temperature corrosion and the deliquescent phenomenon are
Limited to only a small capacity sub-bug filter, and a large capacity main bug filter is on the safe side, so repair work costs can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an outline of a discontinuous combustion type refuse incineration facility provided with measures against dioxins according to the present invention.

FIG. 2 is a schematic flowchart mainly showing flows of gas, air, fly ash, and water in an incineration facility.

FIG. 3 is a chart showing a temperature rising and starting process.

FIG. 4 is a chart showing a normal operation process.

FIG. 5 is a chart showing a falling step.

FIG. 6 is a diagram showing an outline of a conventional bag filter for an incinerator used as a measure against bypass during startup work.

FIG. 7 is an exhaust gas treatment process chart showing a typical example of a conventional exhaust gas treatment method for removing dioxins.

[Explanation of symbols]

1 incinerator 2 reburn chamber 3 gas temperature reduction equipment 31 air preheater 32 heat exchanger group 33 gas cooling room 4 main bug filters 5 Sub bag filter 53 discharging means 57 switching means 82 Chemicals for neutralizing acidic harmful gases (chemicals for neutralizing harmful gases) 84 carbon adsorbent

Continued front page    F term (reference) 3K065 AA16 AB01 AC01 HA02 HA03                 3K070 DA04 DA05 DA07 DA09 DA16                       DA24 DA32 DA37 DA75                 4D002 AA21 AB01 AC04 BA03 BA04                       BA13 BA14 DA05 DA41 EA01                       EA07 FA02 HA07                 4D058 JA04 KB20 RA11 TA02 TA03                       UA03

Claims (2)

[Claims] 1. When incinerating refuse such as general waste or industrial waste, exhaust gas discharged from a discontinuous combustion type refuse incinerator that is decommissioned for a predetermined time every day is supplied to a reburn chamber and a gas temperature reducing facility. After passing through the bag filter, the harmful gas neutralizing agent and the carbon-based adsorbent supplied to the bag filter are used to filter, neutralize and adsorb soot and acidic harmful gases and dioxins contained in the exhaust gas. In a non-continuous combustion type refuse incineration facility configured to remove the bag filter, the bag filter is a sub bag filter that is also used during startup / shutdown and during normal operation, and normal operation with a larger capacity than the sub bag filter. And a main bag filter for use, wherein the discharging means for discharging the collected ash of the sub bag filter is connected to the reburn chamber via the switching means and the collected ash transfer mechanism. Dioxins reduction apparatus of continued combustion waste incineration facility. 2. The gas dehumidifying equipment is provided with a heat exchanger group such as an air preheater for high temperature and an air heater for white smoke prevention in front, and a water injection type gas cooling chamber in back. The dioxin reduction device of the discontinuous combustion type refuse incineration facility according to claim 1.