JPH08206426A - Exhaust gas treatment apparatus for refuse incinerator - Google Patents

Abstract

PURPOSE: To facilitate the treatment of collected dust and ash and to reduce the consumption of calcium hydroxide by removing separately hydrogen chloride, sulfur oxide and heavy metals, and dioxin in exhaust gas from a refuse incinerator. CONSTITUTION: A bag filter 10 in a preceding stage and a bag filter 20 in a succeeding stage are provided. A spray nozzle 22 for spraying calcium hydroxide 2 and a cooler 3 for cooling collected dust and ash are installed in the bag 20, and a spray nozzle 12 for spraying the dust and ash cooled by the cooler 3 into the bag filter 10 is installed. Heavy metals, dioxin, etc., are removed by the bag filter 10, while hydrogen chloride, sulfur oxide, etc., are removed by the bag filter 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treating apparatus for a refuse incinerator.

[0002]

2. Description of the Related Art Recently, a bag filter system is mainly used as a waste gas treatment apparatus for a refuse incinerator in consideration of removal of dioxins. Here, the bag filter means a reaction dust collector in which slaked lime or the like is attached to the surface of the filter cloth.

FIG. 2 shows an exhaust gas treating apparatus for a refuse incinerator using a conventional bag filter method. The slaked lime e is blown into the bag filter b by the blower f from the injection nozzle g, the slaked lime e is attached to the surface of the bag filter to form a layer of slaked lime, and soot and dust in the exhaust gas a of the refuse incinerator are removed. Of these, heavy metals and dioxins are mainly collected and removed by the slaked lime layer formed on the surface of the bag filter, and hydrogen chloride and sulfur oxides are removed by reacting with the slaked lime layer on the surface of the bag filter.

[0004]

When a single bag filter is used to remove heavy metals, dioxins, hydrogen chloride, sulfur oxides, etc. collectively, heavy metals and dioxins are formed on the surface of the bag filter as described above. It is collected and removed in the slaked lime layer. However, since blown slaked lime must be used in an equivalent ratio or more necessary to remove only hydrogen chloride and sulfur oxides, the collected dust ash contains a large amount of unreacted slaked lime. , The amount increases,
In addition, since it contains a large amount of alkali, it has been difficult to prevent the elution of a large amount of heavy metals contained in dust collecting ash.

The present invention reduces the use amount of such slaked lime and the generation amount of dust collection ash, which have been found in the prior art, and reduces harmful substances such as heavy metals and dioxins and acidic substances such as hydrogen chloride and sulfur oxides. It is intended to provide an exhaust gas treatment device for a refuse incinerator that efficiently removes gas and gas.

[0006]

A waste incinerator exhaust gas treatment apparatus of the present invention is a waste incinerator exhaust gas treatment apparatus having a bag filter, which is provided with front and rear bag filters, and the rear bag filter is slaked lime. And a cooling means for cooling the dust collecting ash, and a means for blowing the dust collecting ash cooled by the cooling means into the bag filter at the preceding stage.

[0007]

In the present invention, the dust ash of the post-stage bag filter, which will be described later, is cooled and blown into the pre-stage bag filter, whereby the pre-stage bag filter mainly removes heavy metals and dioxins in the exhaust gas of the refuse incinerator. It

By blowing slaked lime into the bag filter in the latter stage, hydrogen chloride, sulfur oxides, etc. in the exhaust gas of the refuse incinerator, which has been treated in the bag filter in the former stage and from which heavy metals and dioxins have been removed, can be efficiently removed.

The dust collecting ash of the bag filter of the latter stage is cooled and blown into the bag filter of the former stage together with unreacted slaked lime.

The present inventor effectively removes heavy metals and dioxins in exhaust gas by removing hydrogen chloride and sulfur oxides and cooling unreacted slaked lime-containing dust ash in a subsequent bag filter. It has been found that the removal rate can be remarkably increased by applying the method. In the present invention,
By blowing the dust ash of the bag filter of the latter stage containing cooled unreacted slaked lime, which enhances the removal rate of heavy metals and dioxins in the exhaust gas, into the bag filter of the former stage, the heavy metal and dioxins in the exhaust gas of the former bag filter are increased. Etc. can be removed efficiently.

In this way, the collected dust ash containing unreacted slaked lime collected by the bag filter of the latter stage is reused by the bag filter of the former stage, and the heavy metal and dioxin etc. are removed by the bag filter of the former stage. By removing hydrogen chloride and sulfur oxides with a bag filter in the latter stage, it is possible to efficiently collect the respective dust collecting ash in a form that can be easily treated.

Further, the dust collection ash of the front bag filter has a high content of heavy metals but a relatively low alkali content, and the dust collection ash of the back bag filter has a high content of alkali but a low content of heavy metals. This makes it easy to prevent elution of such substances.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIG. Reference numerals 10 and 20 denote front and rear bag filters, respectively. An outlet of the front bag filter 10 and an inlet of the rear bag filter are connected by a pipe 6, and both bag filters 10 and 20 are arranged in series. There is.

The pipe 6 is connected to a blower 21 and a spray nozzle 22 connected to a pipe 23 to which the slaked lime 2 is supplied.
It has. A pipe 24 having a valve 24a is connected to the bottom of the bag filter 20 in the latter stage, and a pipe 25 branched from the pipe 24 and having a valve 25a is connected to the inlet side of the cooler 3.

The inlet side pipe 5 of the upstream bag filter 10 through which the exhaust gas 1 of the refuse incinerator flows is equipped with a spray nozzle 12, and the spray nozzle 12 is connected to the blower 11 by a pipe 13, and the pipe 13 has the above-mentioned structure. The pipes 26 from the cooler 3 join together.

Reference numeral 4 is a processing gas discharged from the bag filter 20 in the latter stage, and 14 is a pipe for discharging dust collecting ash, which is connected to the bottom of the bag filter 10 in the former stage and has a valve 14a.

In this embodiment, the slaked lime 2 is blown by the blower 21.
Is sprayed from the spray nozzle 22 into the pipe 6, and the slaked lime 2 is blown into the bag filter 20 at the subsequent stage. With this slaked lime 2, hydrogen chloride and sulfur oxides in the exhaust gas of the refuse incinerator are treated by the bag filter 20 in the latter stage, as will be described later.

The dust collecting ash containing unreacted slaked lime generated in the bag filter 20 in the subsequent stage is backwashed to the pipes 24, 25.
After being introduced into the cooling device 3, the cooling device 3 is cooled. The dust collecting ash containing the unreacted slaked lime is introduced into the pipe 13 through the pipe 26, and is blown by the blower 11 to the spray nozzle 1
2 is sprayed into the pipe 5 and blown into the bag filter 10 at the preceding stage to form a powder layer on the filter cloth surface of the bag filter 10. On the other hand, the remaining part of the dust collection ash is pipe 24
Is discharged through.

As described above, the preceding bag filter 1
The dust collection ash blown into 0 to form a layer collects and removes heavy metals, dioxins and the like in the exhaust gas 1 of the refuse incinerator introduced into the bag filter 10 in the preceding stage from the pipe 5. The exhaust gas from which heavy metals and dioxins and the like have been removed by the bag filter 10 in the front stage enters the bag filter 20 in the rear stage through the pipe 6, and as described above, hydrogen chloride and sulfur oxides are removed as the treated gas 4 as described above. Is discharged.

As described above, in this embodiment, the bag filter 10 at the front stage removes heavy metals and dioxin, and the bag filter 20 at the rear stage removes hydrogen chloride and sulfur oxides. Efficient removal can be performed and each dust ash can be recovered in a form that can be easily treated. Further, the dust collection ash of the front bag filter 10 has a large heavy metal content but a relatively low alkali content, while the dust collection ash of the rear bag filter 20 has a high alkali content but a low heavy metal content. The process for preventing the elution of lead, etc. becomes easy.

Moreover, a part of the dust-collecting ash containing unreacted slaked lime in the bag filter 20 in the latter stage is cooled by the cooler 3 and blown into the bag filter 10 in the former stage, so that it is explained in the action column. Moreover, slaked lime can be effectively used to effectively remove heavy metals, dioxins and the like in exhaust gas, and the consumption thereof can be reduced.

[0022]

According to the present invention, a means for blowing slaked lime and a cooling means for cooling the dust collecting ash are provided in the bag filter in the latter stage, and a means for blowing the dust collecting ash cooled by the cooling means in the bag bug in the former stage. The provision of the following effects can be achieved. (1) The amount of slaked lime can be reduced and unreacted slaked lime can be effectively used, which contributes to a reduction in running cost. (2) Collecting dust ash in a form that is easy to process by removing harmful substances such as heavy metals and dioxins mainly with the bag filter in the first stage and hydrogen chloride, sulfur oxides, etc. with the second bag filter. However, it is possible to treat according to its characteristics. (3) By reducing the amount of slaked lime, less dust ash is generated.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an embodiment of the present invention.

FIG. 2 is a conceptual diagram of an exhaust gas treatment device of a conventional refuse incinerator.

[Explanation of symbols]

 1 Waste gas from waste incinerator 2 Slaked lime 3 Cooler 4 Process gas 10 Previous bag filter 11 Blower 12 Spray nozzle 13 Piping 20 Rear bag filter 21 Blower 22 Spray nozzle 23, 24, 25, 26 Piping

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical indication location B01D 53/68 53/70 53/64 B01D 53/34 134 E E 136 Z

Claims (1)

[Claims] 1. An exhaust gas treatment apparatus for a refuse incinerator having a bag filter, which comprises a front-stage bag filter and a rear-stage bag filter, and a rear-stage bag filter is provided with a means for blowing slaked lime and a cooling means for cooling dust ash, Further, there is provided a means for blowing the dust collecting ash cooled by the cooling means into a bag filter at a preceding stage, the waste gas treatment device for a refuse incinerator.