JP2002048331A - Flue-gas treatment system for incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flue gas-treatment system for incinerator, in which dioxin and related compounds included in flue gas of an incinerator 1 is removed economically, efficiently and stably by a simple structure. SOLUTION: A bag filter 3 and an adsorption tower 4 of an adsorbent- containing fixed-bed type are provided in this order from the upstream of flue- gas line 6a-6d of the incinerator 1. A filer aid 9 is applied on the surface on the flue-gas inflow side of a filter medium 7a of the bag filter 3. Cleaning of the filter medium is not carried out during the flue-gas treatment.

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 system for preventing dioxins from being emitted from exhaust gas from incinerators and crematoriums.

[0002]

2. Description of the Related Art Exhaust gas discharged from incinerators and crematoriums is known to contain highly toxic dioxins, but there is a demand for efficient and economical removal of these. . At this time, since the crematorium is installed in a limited place such as a desert, the means for removing dioxins must be compact.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas treatment system suitable for removing dioxins contained in exhaust gas from incinerators and crematoriums.

[0004]

In order to achieve the above object, an exhaust gas treatment system for an incinerator according to the present invention, as described in claim 1, comprises a bag filter and an adsorbent in an exhaust gas path of an incinerator in order from an upstream side. A storage type fixed bed type adsorption tower is provided, and at this time, a filter aid is applied to the surface of the filter material of the bag filter on the exhaust gas inflow side.

[0005] According to this, the filtration performance of the bag filter is dramatically improved by the filter aid, so that the bag filter removes particulate dioxins contained in the exhaust gas and most of the other dust adhering to the dioxins. Will do. The adsorbent-fixed fixed-bed adsorption tower stably adsorbs and removes gaseous dioxins contained in the exhaust gas flowing out of the bag filter with a simple structure. In order to suppress the contamination of the adsorbent in the fixed bed type adsorption tower containing the agent,
The adsorbent-containing fixed-bed adsorption tower can adsorb and remove dioxins satisfactorily and stably over a long period of time.

In the adsorbent-containing fixed bed type adsorption tower, the exhaust gas treatment chamber sandwiching the activated carbon group between the pair of ventilation walls in the longitudinal direction in the closed box is opposed at a fixed distance. The exhaust gas flows into the inner space between the opposed processing chambers and is discharged toward the outer space of each processing chamber. According to this, the removal performance of dioxins becomes economical and stable, and the apparatus becomes compact.

As the incinerator of the present invention, it is particularly advantageous to form a cremation furnace as described in claim 3. According to this, the operating characteristics of a cremation furnace in which a single cremation time is about 1 to 1.5 hours, and the concentration of dust (soot) in exhaust gas is 100 mg / Nm ³ or less. The combination of the bag filter and the adsorbent-containing fixed-bed adsorption tower is particularly effective in removing dioxins due to the exhaust gas characteristics of crematory furnaces, which contain less adsorbate gas such as hydrochloric acid and sulfur oxides contained in the exhaust gas. In addition, the adsorbent adsorption capacity of the adsorbent-containing fixed-bed adsorption tower is maintained for a longer period of time.

Further, the bag filter is characterized in that the dust attached to the surface of the filter material on the exhaust gas inflow side is backwashed by a jet pulse while the operation of the incinerator is stopped. It shall be provided with. According to this, the situation where dioxins pass through the filter cloth material and are released to the outside air during the operation of the cleaning means can be more reliably prevented.

[0009]

FIG. 1 is a block diagram showing an embodiment of an exhaust gas treatment system for an incinerator according to the present invention. In this figure, reference numeral 1 denotes a cremation furnace as a kind of incinerator; An air cooling unit, 3 is a bag filter, 4 is a fixed bed type adsorption tower containing an adsorbent, 5 is a blower, and 6a to 6d are exhaust gas pipes forming an exhaust gas path.

The cremation furnace 1 is currently in general use and has a main combustion chamber 1a and a reburn chamber 1b. The main combustion chamber 1a has a main combustion burner, and the reburn chamber has a 1b reburn burner. It has been provided.

The air cooling unit 2 rapidly cools the high-temperature exhaust gas discharged from the cremation furnace 1 to 200 ° C. (preferably 130 to 18 ° C.).
(0 ° C.) or lower and discharged toward the bag filter 3. At this time, as means for rapidly cooling the exhaust gas, outside air is allowed to flow into the exhaust gas, or heat exchange is performed between the exhaust gas and a cooling medium such as water.

The bag filter 3 removes dust and particulate dioxins contained in the exhaust gas when the exhaust gas flowing out of the air cooling unit 2 flows in and passes through the filter material.
The exhaust gas treated in this way is allowed to flow out to the adsorbent-containing fixed-bed adsorption tower 3 and is configured as follows in detail.

That is, a main body casing 3a having an airtight space inside is provided, and a plurality of filter bags as a filtering material formed as an elongated bag made of a filter material 7a are provided in an upper inside portion of the casing 3a. 7 is provided in a suspended manner, a lower space of the partition 8 is defined as an exhaust gas inflow side space a, and an upper space of the partition wall 8 is defined as an exhaust gas outflow side space b.

As shown in FIGS. 2 and 3, each bag filter 7 is coated with a precoat agent 9 as a filter aid on the surface of the filter material 7a facing the exhaust gas inflow side space a.
In this case, an inorganic material, such as diatomaceous earth or clay (clay), which is stable for a long period of time without reacting or deteriorating therewith upon contact with the harmful gas is used as the precoating agent 9. When the precoating agent 9 enters the texture of the surface of the filter material 7a, the thickness of the precoating agent 9 becomes approximately 100 μm to 20 μm.
The dense filtration layer 10 of about 0 μm is formed. In the dense filtration layer 10, the particles 9a of the precoat agent 9 are formed in a denser state than the gaps between the fibers s of the filter material 7a, and the air permeability is maintained well.

An exhaust gas inlet pipe 11a for allowing the exhaust gas flowing out of the air cooling unit 2 to flow into the inflow side space a is provided in a casing 3a covering the side surface of the exhaust gas inflow side space a.
A baffle plate 12 for blocking the flow of the exhaust gas flowing from the exhaust gas inlet pipe 11a and changing the flow direction of the exhaust gas vertically is fixed inside the exhaust gas inflow side space a. It is.

A bottom portion of the exhaust gas inflow side space a is formed as a hopper portion c having a narrow width as it goes downward, and a screw conveyor 13 is formed at the lowermost portion of the hopper portion c so as to face forward and backward. The screw conveyor 13 is driven to rotate by a motor 14 and conveys dust and particulate dioxins accumulated at the lowermost portion of the hopper c to another place through an opening provided with an on-off valve 15.

On the other hand, an exhaust gas outlet pipe 11b for allowing the exhaust gas in the outflow space b to flow toward the adsorbent-fixed fixed-bed type adsorption tower 4 is provided in the casing 3a covering the side surface of the exhaust gas outflow space b. In the known exhaust gas discharge side space b, repeated injection of compressed air into each filter bag 7 instantaneously, that is, generation of a compressed air jet pulse, is repeated. Jet pulse backwash means 16 is provided. The jet pulse backwashing means 16 instantaneously oscillates the corresponding filter bag 7 due to the pressure wave of the compressed air ejected, and removes dust and dioxins adhering to the surface of the bag filter 3 facing the exhaust gas inflow side space a. The cremation furnace 1 operates so as to remove particles, and can operate under a state in which the operation of the crematorium 1 is stopped. The backwash means that the jet pulse travels in the direction opposite to the exhaust gas flow direction of the bag filter to remove dust attached to the filter bag 7.

The adsorbent-containing fixed-bed adsorption tower 4 receives the exhaust gas flowing out of the bag filter 3 and passes through the interparticle gaps of the adsorbent, thereby adsorbing and removing dioxins contained in the exhaust gas and blowing the exhaust gas. It is intended to be spilled out, and the details are as follows.

That is, FIG. 4 is a plan view showing the adsorbent-containing fixed bed type adsorption tower 4 according to the present invention, FIG. 5 is a sectional view showing an xx part of FIG. 4, and FIG. It is a side view of the tower 4. In these figures, reference numeral 17 denotes a rectangular box-shaped casing, and its internal space d has a pair of ventilation walls 18a, 1a.
8b, an exhaust gas treatment chamber 20 for sandwiching a group of activated carbons 19 as an example of a dioxin-type adsorbent in a layered manner is disposed facing each other at a predetermined distance in the vertical direction. Here, as the dioxin adsorbent, activated coke or the like may be used instead of activated carbon. An area between the processing chambers 20 facing each other is defined as an exhaust gas inflow side space e, and an outer area of each of the processing chambers 20 is defined as an exhaust gas outflow side space f.

Square box members 21 for projecting a space in each of the processing chambers 20 project from the upper wall 17a of the box-shaped casing forming the upper surface of each of the processing chambers 20.
Opening / closing lids 22 and 22 at the upper end opening portions of
A hopper-shaped cylindrical body 23 for opening a space in the processing chamber 20 is fixed to a box-shaped casing lower surface wall 17b forming a lower surface of each processing chamber 20 in a hanging manner. Opening / closing lids 24, 24 are also attached to the locations. At this time, each of the ventilation walls 18a and 18b is formed with a large number of through holes g, and each of the through holes g is, for example, an open (thin) hole having a diameter of about several mm.

When the processing chambers 20 and 20 are filled with the activated carbon 19, the diameter is approximately several meters through the upper rectangular tube member 21.
m of granulated activated carbon 19 is supplied, and the layer thickness of the activated carbon 19 group formed in this way is about 400 mm so as to form a low pressure loss structure.

Reference numeral 25 denotes a single exhaust space chamber formed continuously with the box-shaped casing lower surface wall 17b. This space chamber 25 is provided in each of the gas outflow spaces f, f with a ventilation passage h formed on the bottom surface thereof. , H. The exhaust space chamber 25 may be formed continuously above the box-shaped casing 17.

In FIG. 6, an exhaust gas pipe 6b for flowing the exhaust gas of the cremator furnace 1 is connected to a left wall 17c of the box casing which is a left surface of the exhaust gas inflow side space e, and a right wall of the exhaust space chamber 25. Is connected to an exhaust gas pipe 6c through which exhaust gas existing inside is discharged toward the blower 5.

During use of the adsorbent-containing fixed-bed adsorption tower 4, the exhaust gas of the crematorium 1 is brought to a temperature of about 130 ° C. to 180 ° C. and passes through the exhaust gas pipe 6b to form an exhaust gas inlet space e. And subsequently passed through a pair of processing chambers 20, 20 in which activated carbon 19 groups were present in parallel, into the exhaust gas outlet side spaces f, f, and subsequently collected in the exhaust space chamber 25. Thereafter, the gas is discharged toward the blower 5 through the exhaust gas pipe 6c.

At this time, the activated carbon 19 group in each of the processing chambers 20 and 20 adsorbs and removes dioxins contained in the exhaust gas passing between the particles, and the activated carbon fixed layer during this operation is removed. The pressure loss of the entire adsorption tower 4 is a low pressure loss of about 0.5 kpa or less under a gas flow velocity of 0.3 m / sec to 0.4 m / sec.

The dioxin adsorption capacity of the activated carbon 19 group in each of the processing chambers 20 and 20 is such that the exhaust gas of the crematorium 1 is sulfur oxide. Is maintained for a relatively long time because it has a characteristic that it does not contain a large amount of adsorbate gas. Therefore, even if the activated carbon 19 group is fixedly present in the processing chamber 20, there is no inconvenience in performance and maintenance management. . In addition, since the activated carbon fixed bed type adsorption tower 4 of this example has a fixed activated carbon bed in which the activated carbon 19 is periodically replaced (fixed bed type), dioxins are always stably removed with high efficiency.

When the dioxins adsorption capacity of the activated carbon 19 group in the processing chamber 20 becomes insufficient and the amount of dioxins discharged by the exhaust gas approaches 0.1 ng-TEQ / Nm3, the lower hopper-like cylinder 23 Opening and closing lid 24, 24
Is opened, the activated carbon 19 group is taken out, and new activated carbon 19 is supplied from above through the square tubular members 21 as described above.

At this time, the activated carbon 19 group is divided into the processing chambers 20 and 20.
Since the hopper-shaped cylindrical body 23 is inclined downward toward the opening thereof from the inside due to its own weight, and the hopper-shaped cylindrical body 23 is inclined downward toward the opening, the activated carbon 19 group is formed only by its own weight. It falls completely without remaining on the bottom.

Next, an example of use and operation of the exhaust gas treatment system of the present invention will be described. After placing the coffin in the main combustion chamber 1a of the cremation furnace 1, the cremation furnace 1 is brought into an operating state. On the other hand, the blower 5 is operated to suck the exhaust gas generated in the cremation furnace 1. In the operation state of the crematorium 1, the fuel supplied to the main combustion chamber burner burns together with the coffin, and the exhaust gas generated by this combustion flows into the reburning chamber 1b, where unburned gas and odor components are reburned. Is decomposed. The combustion temperature in the main combustion chamber 1a and the re-combustion chamber 1b is maintained at about 800 ° C. or higher to suppress the generation of dioxins.

The exhaust gas generated in the cremation furnace 1 flows into the air cooling unit 2 with a dust concentration of approximately 100 mg / Nm ³ , where it is rapidly cooled to 200 ° C. or less. This allows
Particle formation of dioxins contained in the exhaust gas is promoted, and a state in which resynthesis of dioxins occurs in the bag filter 3 and the fixed bed type adsorption tower 4 containing the adsorbent is suppressed.

The exhaust gas flowing out of the air cooling unit 2 flows toward the bag filter 3 and flows into the exhaust gas inflow space a via the exhaust gas inlet pipe 11a. The filter material 7 reaches the plurality of filter bugs 7 in an equalized manner, and is then filtered by passing the filter material 7a coated with the precoat agent 9 toward the exhaust gas outflow side space b.

When the state of this filtration is observed microscopically with reference to FIG. 3, the exhaust gas passes between the particles of the dense filtration layer 10 composed of a group of relatively small particles 9a having a diameter of about 10 μm of the precoating agent 9 and is further purified. It reaches the exhaust gas outflow side space b through the relatively coarse weave of the filter material 7a composed of the fibers s of about 15 μ to 20 μ. By the passage of the exhaust gas, ash particles and dioxins in the exhaust gas to which dioxins are adhered are effectively separated by the fine filtration layer 10 and remain on the surface of the fine filtration layer 10. Then, as the passage time of the exhaust gas passes, the ash particles and the like become a dust layer j and accumulate on the surface of the dense filtration layer 10.

Here, for reference, the filtration situation in the case where the dense filtration layer 10 by the precoat agent 9 is not formed on the surface of the filter material 7a is shown for comparison. As shown in FIG. This tends to penetrate deep into the gaps of the fibers s of the filter material 7a, which increases the exhaust gas filtration resistance and causes a reduction in the processing capacity, and also causes the filter material 7a to pass through the filter material 7a depending on the operating conditions. is there.

If the deposition thickness of the dust layer j on the dense filtration layer 10 exceeds a certain size, the pressure loss caused by the passage of the exhaust gas becomes excessive, and the exhaust gas cannot be processed properly. In order to avoid this, the jet pulse backwashing means 16 is operated while the operation of the incinerator 1 is stopped.
Is operated to separate the dust layer j from the filter bag 7 and drop it. The separated dust layer j component falls to the lowermost part of the exhaust gas inflow side space a.
In discharging the dust, the screw conveyor 13 is operated after the on-off valve 15 is opened.

By the way, when the jet pulse backwashing means 16 is operated during the operation of the cremation furnace 1, a part of the ash particles and the dioxin particles of the dust layer j move through the dense filtration layer 10 in the exhaust gas outflow direction and the exhaust gas is discharged. It is requested that the cleaning process by the jet pulse backwashing means 16 should not be performed during the operation of the crematorium 1 because there is a possibility of flowing into the outflow side space b. The following is a description of an example of specific operating conditions of the present invention.

That is, the filtration speed FV, the exhaust gas inlet pipe 11
The dust concentration Ci in the exhaust gas in a and the operating time H of the single incineration treatment of the crematorium 1 are expressed as FV = 1.0 to 2.0 m ³ / m.
in. at 200 ° C. or less, Ci = 100 mg / N
It is assumed that m ³ and H = 1 to 1.5 hr. in this case,
The dust amount M on the surface of the dense filtration layer 10 is represented by M = Ci * FVa * 60 * H. Here, FVa = (1.5 to 2.00) * 273 / (2
73 + 200) = 0.87-1.15 Nm ³ / min. / M ² Therefore, M = 5.22 to 10.4 g / m ² The average thickness t of this dust amount M is, assuming that the bulk specific gravity of the dust layer j component is 0.5, t = 10.4 to 20.g / m ² . 8 μm
Becomes

That is, when the cremation process is performed once by the cremation furnace 1, about 10.4 to 20.8
A dust layer j having a thickness of μm is formed. The dust layer j of this thickness has a small dust load on the surface of the dense filtration layer 10, and therefore, it is not necessary to perform the cleaning process during the operation of the crematorium 1, and can meet the above-mentioned demand. It is. In practice, in many cases, it is sufficient to perform the cleaning treatment of the fine filtration layer 10 about once a day.

The dust concentration of the exhaust gas that has reached the exhaust gas outflow side space b is equal to that of a normal bag filter in which the dense filtration layer 10 is not formed by the precoating agent 9.
It is about 1 / mg / Nm ³ , and almost 100% of dioxins attached to ash particles and the like and particulate dioxins are collected and removed. The exhaust gas in this state flows out through the exhaust gas outlet pipe 11b toward the adsorbent-containing fixed-bed adsorption tower 4.

When the exhaust gas reaches the adsorbent-containing fixed bed type adsorption tower 4, it first flows into the exhaust gas inflow side space d,
Subsequently, a pair of processing chambers 20 and 20 in which the activated carbon 19 is stored.
And flows into the exhaust gas outflow side space f at the same time in parallel, and after being collected in the exhaust space chamber 25, flows out to the blower 5.

At this time, the activated carbon 19 group in each of the processing chambers 20 and 20 adsorbs and removes gaseous dioxins contained in the exhaust gas passing between the particles, and contains adsorbent during this operation. The pressure loss of the entire fixed bed type adsorption tower 4 is about 0.5 kpa or less under a gas flow velocity of 0.3 m / sec to 0.4 m / sec.

The dioxin adsorption capacity of the activated carbon 19 group in each of the processing chambers 20 is determined by the fact that the exhaust gas from the crematorium 1 Therefore, the activated carbon 19 group is maintained for a relatively long time because it has a characteristic of not containing a large amount of adsorbate gas. Absent.

Further, since the exhaust gas from which most of the dust has been removed by the bag filter 3 flows into the activated carbon 19 group, the progress of the contamination of the activated carbon 19 is greatly suppressed, and its dioxin adsorption capacity is maintained for a long time. Be maintained.

During the treatment of such an exhaust gas, the dioxin adsorption capacity of the activated carbon 19 group in the treatment chamber 20 becomes insufficient, and the amount of dioxins discharged by the exhaust gas is 0.1 ng-.
When approaching TEQ / Nm 3, the open / close lids 24, 24 of the lower hopper-shaped cylindrical body 23 are opened to open the activated carbon 19.
The group is taken out, and new activated carbon 19 is supplied from above through the square tubular members 21 as described above.

At this time, the activated carbon 19 group is divided into the processing chambers 20, 20.
Since the hopper-shaped cylindrical body 23 is inclined downward toward the opening thereof from the inside due to its own weight, and the hopper-shaped cylindrical body 23 is inclined downward toward the opening, the activated carbon 19 group is formed only by its own weight. It falls completely without remaining on the bottom.

Exhaust gas flowing out of the exhaust space chamber 25 of the adsorbent-containing fixed bed type adsorption tower 4 is sucked into the suction port of the blower 5 and is jetted from the discharge port. The jetted exhaust gas is not shown. Released into the atmosphere via a chimney.

[0046]

According to the present invention configured as described above, the following effects can be obtained. That is, according to the first aspect of the present invention, the filtration performance of the bag filter is dramatically improved by the filter aid, most of the particulate dioxins are removed, and the adsorbent-containing fixed-bed adsorption tower is used. Removes gaseous dioxins contained in exhaust gas with low dust concentration, so that dioxins contained in exhaust gas from incinerators can be economically, effectively and stably removed over a long period of time, and It is possible to make the overall configuration a relatively simple structure.

According to the second aspect, gaseous dioxins can be stably adsorbed and removed with a relatively inexpensive adsorbent.

According to the third aspect, the operating characteristics of the cremation furnace in which batch processing is performed for a single processing time of about 1 to 1.5 hours, and the dust concentration is 100 mg / N
m ³ or less and the concentration of adsorbate gas such as hydrochloric acid and sulfur oxide is low, so that the adsorbent adsorption capacity of the adsorbent-containing fixed-bed adsorption tower is maintained for a long time Therefore, it is economical, and the bag filter can be cleaned without any trouble while the operation of the crematorium is stopped. Therefore, the emission of dioxins into the atmosphere can be more reliably prevented. Furthermore, since most dioxins are removed by a bag filter from exhaust gas before reaching the adsorbent-containing fixed bed adsorption tower, the processing capacity of the adsorbent-containing fixed bed adsorption tower becomes relatively small,
This makes the overall configuration of the exhaust gas treatment device compact and makes it possible to conveniently install it in a recreation area.

According to the fourth aspect of the present invention, the fine filtration layer of the bag filter can be cleaned without releasing dioxins into the atmosphere, so that particulate dioxins can be removed more reliably and labor saving. Can be done.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of an exhaust gas treatment system for an incinerator according to the present invention.

FIG. 2 is a partial cross section showing a dust accumulation state of a dense filtration layer in a bag filter of the exhaust gas treatment system, where A is a schematic diagram and B is an enlarged view.

FIG. 3 is a partial cross-sectional view showing a dust accumulation state on a filter material surface of a general bag filter, wherein A is a schematic view and B is an enlarged view.

FIG. 4 is a plan view showing an adsorbent-containing fixed-bed adsorption tower of the exhaust gas treatment system.

FIG. 5 is a sectional view showing an xx section of FIG. 4;

FIG. 6 is a side view of the fixed bed type adsorption tower.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 incinerator 3 bag filter 4 adsorbent-containing fixed-bed adsorption tower 6 a to 6 d exhaust gas pipe (exhaust gas path) 7 a filter material 9 precoat agent (filtration aid) 16 jet pulse backwashing means (cleaning means) 19 activated carbon (adsorption) Agent)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23G 5/44 ZAB B01D 53/34 134E

Claims (4)

[Claims] 1. A bag filter and an adsorbent-containing fixed-bed adsorption tower are provided in the exhaust gas path of an incinerator in order from the upstream side. At this time, a filter aid is coated on the surface of the filter material of the bag filter on the exhaust gas inflow side. An exhaust gas treatment system for an incinerator, wherein the filter material is not cleaned during the treatment of the exhaust gas in addition to the waste gas. 2. An exhaust gas treatment chamber in which an activated carbon group is sandwiched between a pair of ventilation walls in a vertical direction in a closed box body in which an adsorbent-containing fixed-bed adsorption tower is disposed at a predetermined distance from each other. The exhaust gas treatment system for an incinerator according to claim 1, wherein the exhaust gas flows into the inner space and is discharged toward the outer space in each processing chamber. 3. The exhaust gas treatment system for an incinerator according to claim 1, wherein the incinerator is a cremation furnace. 4. The bag filter is provided with cleaning means for backwashing dust adhering to the surface of the filter material on the exhaust gas inflow side with a jet pulse while the operation of the incinerator is stopped. Claim 1, 2, or 3
An exhaust gas treatment system for an incinerator according to the above.