JP2000042362A - Waste gas treating device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize activated carbon used for removing dioxin in a waste gas and/or alkali used of removing acid gases such as hydrogen chloride or sulfur oxide. SOLUTION: After a waste gas exhausted from a kiln 11 is cooled in a waste gas cooling column 12, dust is removed and incineration fly ash is recovered in a 1st dust collector 13. Activated carbon is added from an activated carbon adding device 15 to the waste gas discharged from the 1st dust collector 13 to adsorb dioxin contained in the waste gas and after the activated carbon adsorbing the dioxin is recovered in a 2nd dust collector 14, the waste gas is further discharged to the atmosphere from a stack 16. The activated carbon recovered in the 2nd dust collector 14 is effectively utilized as fuel for the kiln 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for treating exhaust gas, and more particularly to treating an exhaust gas from a kiln which generates an acidic gas such as dioxin, hydrogen chloride and sulfur oxide using an alkali such as activated carbon or slaked lime. Apparatus and method.

[0002]

2. Description of the Related Art In recent years, the amount of waste such as municipal solid waste has increased remarkably, and for the purpose of effective use and recycling of such waste,
Attempts have been made to produce environmentally friendly cement (hereinafter referred to as ecocement) using incinerated ash from municipal solid waste as part of the raw material. Eco-cement is produced by mixing incinerated ash with natural raw materials such as limestone and clays to prepare a cement-mixed raw material and firing it in a rotary kiln or the like.

[0003] Since municipal solid waste incineration ash and the like are used as a part of the raw material, the exhaust gas generated from the rotary kiln may contain acidic gases such as dioxin, hydrogen chloride and sulfur oxide. In the exhaust gas treatment device shown in FIG. That is, after the exhaust gas discharged from the kiln 1 is cooled in the exhaust gas cooling tower 2, an activated carbon and an alkali such as slaked lime are added to the exhaust gas. As a result, the dioxin contained in the exhaust gas is adsorbed on the activated carbon, and the acidic gas such as hydrogen chloride or sulfur oxide reacts with the alkali to be removed. Next, dust is removed by the dust remover 3. At this time, activated carbon to which dioxin is adsorbed together with incineration fly ash from the exhaust gas and alkali used to remove acidic gases such as hydrogen chloride and sulfur oxide are collectively collected. Will be gathered. The exhaust gas leaving the dust remover 3 is discharged from the chimney 4 into the atmosphere.

[0004]

However, the activated carbon to which dioxin is adsorbed and the alkali used to remove acidic gases such as hydrogen chloride and sulfur oxides are collected together with the incinerated fly ash. Therefore, these materials cannot be used effectively, and in the past, cement solidified together with incineration fly ash,
It was only used for landfill treatment.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an exhaust gas treatment apparatus and a method capable of effectively utilizing activated carbon used for removing dioxin in exhaust gas. And It is another object of the present invention to provide an exhaust gas treatment apparatus and method capable of effectively utilizing alkali used for removing acidic gases such as hydrogen chloride and sulfur oxides in exhaust gas.

[0006]

An exhaust gas treatment apparatus according to the present invention has a first dust remover for collecting incineration fly ash from exhaust gas generated in a kiln, and an incineration fly ash collected by the first dust remover. Activated carbon addition device for adding activated carbon to exhaust gas to adsorb dioxin in exhaust gas, and second for collecting activated carbon adsorbing dioxin from exhaust gas to which activated carbon is added
And a dust remover. The apparatus further includes an alkali addition device for adding an alkali to the exhaust gas from which the incineration fly ash is collected by the first dust remover to remove acidic gases such as hydrogen chloride and sulfur oxides in the exhaust gas. Can be configured to simultaneously recover the activated carbon and the alkali used.

[0007] Further, an exhaust gas treatment method according to the present invention comprises:
Recover incineration fly ash from the flue gas generated in the kiln, add activated carbon to the recovered flue gas from the incineration fly ash to adsorb dioxin in the flue gas, and recover dioxin-adsorbed activated carbon from the flue gas containing activated carbon Is the way.
In addition, an alkali may be added to the exhaust gas together with the activated carbon to remove an acidic gas such as hydrogen chloride or sulfur oxide in the exhaust gas, and the activated carbon and the alkali used may be simultaneously recovered.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a configuration of an exhaust gas treatment apparatus according to one embodiment of the present invention. An exhaust gas cooling tower 12 is connected to a kiln 11 such as a rotary kiln used for cement production, and a first dust remover 13 and a second dust remover 14 are connected in series to the exhaust gas cooler 12.
An activated carbon adding device 15 is connected between the first dust remover 13 and the second dust remover 14, and a chimney 16 is connected to an outlet side of the second dust remover 14. As the first and second dust removers 13 and 14, various dust removers such as an electric dust collector can be used.

Next, the operation of the exhaust gas processing apparatus according to this embodiment will be described. First, the exhaust gas discharged from the kiln 11 for firing the cement raw material is cooled in the exhaust gas cooling tower 12 to a temperature at which the exhaust gas can be circulated to the first dust remover 13, and then the exhaust gas is cooled by the first dust remover 13. Then, the dust is removed and incinerated fly ash is collected. Next, activated carbon is added to the exhaust gas that has exited the first dust remover 13 from the activated carbon adding device 15, whereby dioxin contained in the exhaust gas is adsorbed on the activated carbon. The exhaust gas to which the activated carbon has been added further enters the second dust remover 14, where the activated carbon having adsorbed dioxin is recovered. Thereafter, the exhaust gas is released from the chimney 16 into the atmosphere.

The activated carbon recovered by the second dust remover 14 is:
The dioxin, which can be used as fuel for the kiln 11 and is adsorbed on the activated carbon, is decomposed by the high-temperature atmosphere in the kiln 11. In cement production facilities,
In many cases, a preheater (not shown) is connected to the kiln 11, but activated carbon recovered by the second dust remover 14 can be used as fuel for the preheater.

The incinerated fly ash collected by the first dust remover 13 can recover heavy metals such as lead and copper by a series of steps as shown in FIG. 2, for example.

As shown in FIG. 3, an alkali addition device 17 is further connected between the first dust remover 13 and the second dust remover 14, and the incinerated fly ash is removed by the first dust remover 13. An alkali such as slaked lime may be added from the alkali addition device 17 to the collected exhaust gas. By the addition of the alkali, acidic gases such as hydrogen chloride and sulfur oxides contained in the exhaust gas are removed by reacting with the alkali, and the alkali used to remove the acidic gases such as hydrogen chloride and sulfur oxides is removed. 2 is collected by the dust remover 14. The recovered alkali is used as a part of the cement raw material, and can be introduced into the kiln 11. That is, it is possible to effectively use the alkali used for removing the acidic gas such as hydrogen chloride and sulfur oxide in the exhaust gas. The alkali added from the alkali addition device 17 includes slaked lime, CaO, CaCO ₃ , NaOH, KO
Various alkalis such as H can be used.

As described above, according to the exhaust gas treatment apparatus according to the above embodiment, the incineration fly ash and the activated carbon adsorbing dioxin and / or the acid gas such as hydrogen chloride and sulfur oxide in the exhaust gas are removed. Since the alkalis used in the process are separately recovered, the activated carbon can be effectively used as a fuel for the kiln 11 and the like, the alkali can be effectively used as a raw material for cement, and the heavy metals can be recovered from the fly ash.

[0014]

As described above, according to the present invention, the present invention is used for removing incinerated fly ash and dioxin-adsorbed activated carbon and / or acid gas such as hydrogen chloride and sulfur oxide in exhaust gas. Since the alkalis are separately collected, the alkali used for removing the activated carbon used for dioxin removal and / or the acidic gas such as hydrogen chloride or sulfur oxide can be effectively used. In addition, it becomes possible to recover heavy metals from incinerated fly ash.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing a process of recovering heavy metals from incinerated fly ash.

FIG. 3 is a block diagram showing an exhaust gas treatment apparatus according to another embodiment.

FIG. 4 is a block diagram showing a conventional exhaust gas treatment device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Kiln 12 Exhaust gas cooling tower 13 1st dust remover 14 2nd dust remover 15 Activated carbon addition device 16 Chimney 17 Alkali addition device

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 4D002 AA02 AA19 AA21 AA28 BA02 BA03 BA04 BA13 BA14 CA01 CA11 DA02 DA03 DA05 DA11 DA12 DA41 EA02 EA05 GA02 GA03 GB03 GB09 HA08 4K056 AA19 BB01 CA11 CA20 DB07 DB14 FA08

Claims (4)

[Claims] 1. A first dust remover for collecting incineration fly ash from flue gas generated in a kiln; and activated carbon is added to the flue gas from which the incineration fly ash is collected by the first dust remover to reduce dioxin in the flue gas. An exhaust gas treatment device comprising: an activated carbon adding device for adsorbing; and a second dust remover for collecting activated carbon having adsorbed dioxin from exhaust gas to which activated carbon has been added. 2. An apparatus for adding an alkali to an exhaust gas from which incineration fly ash is collected by the first dust remover to remove an acid gas such as hydrogen chloride or sulfur oxide in the exhaust gas, further comprising an alkali addition device. The exhaust gas treating apparatus according to claim 1, wherein the second dust remover also recovers an alkali used for removing an acid gas such as hydrogen chloride or sulfur oxide from the exhaust gas. 3. The incineration fly ash is recovered from the exhaust gas generated in the kiln, the activated carbon is added to the exhaust gas from which the incinerated fly ash is recovered to adsorb the dioxin in the exhaust gas, and the dioxin is absorbed from the exhaust gas to which the activated carbon is added. An exhaust gas treatment method comprising recovering activated carbon. 4. An alkali added to an exhaust gas together with activated carbon to remove an acid gas such as hydrogen chloride and sulfur oxide in the exhaust gas, and an alkali used for removing an acid gas such as hydrogen chloride and sulfur oxide from the exhaust gas. The exhaust gas treatment method according to claim 3, wherein the waste gas is recovered.