JP2000320813A - Melting furnace exhaust gas treatment method - Google Patents

Abstract

(57) [Abstract] [Problem] There is no need to provide a dedicated exhaust gas treatment facility.
To provide a method for treating exhaust gas of a melting furnace capable of recovering energy of the exhaust gas discharged from the melting furnace. SOLUTION: This is a method for treating exhaust gas from an incineration residue melting furnace provided in a refuse incineration facility, wherein the exhaust gas generated when the incineration residue is melt-processed in a melting furnace 30 operated in a reducing atmosphere is used as a waste incinerator. To the inlet of the secondary combustion chamber 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating exhaust gas generated when a refuse incineration residue is melt-processed in a melting furnace operated in a reducing atmosphere.

[0002]

2. Description of the Related Art Most municipal solid waste is incinerated in a refuse incineration facility and then disposed of in landfill. However, among the incineration residues generated by the incineration, especially in the disposal of fly ash, landfill disposal cannot be performed unless a treatment for stabilizing heavy metals contained therein is further performed. Also, as incineration ash becomes more difficult to secure in landfills, it has become necessary to reduce its volume and stabilize it.

[0003] For this reason, the treatment of incineration residues has been carried out by a melting method in which volume reduction and stabilization of heavy metals are simultaneously performed. Melting treatment of incineration residues is performed by various methods. However, depending on the melting method, CO gas generated by decomposition of unburned matter in the incineration residues,
The inside of the furnace is kept in a reducing atmosphere by H ₂ gas or the like. As a result, the exhaust gas containing the CO gas and the H ₂ gas at concentrations of several tens of percent each is discharged from the melting furnace.

Conventionally, in a refuse incineration facility having a melting furnace for incineration residues, incineration of the refuse and melting of the incineration residues are carried out, for example, by the method disclosed in JP-A-7-77318. In the method disclosed in Japanese Patent Application Laid-Open No. 7-77318, incineration ash discharged when burning refuse in an incinerator and refuse incineration exhaust gas generated from the incinerator are collected during dust collection processing. Fly ash is sent to the melting furnace, where the incineration residue (incinerated ash and fly ash) is melted. At this time, air is added to the exhaust gas discharged from the melting furnace to burn flammable gas, and then, after a dust collection process, it is released to the atmosphere.

[0005]

Exhaust gas generated from a melting furnace in a reducing atmosphere contains a large amount of flammable gas such as CO gas and H ₂ gas. As a result, the energy of the exhaust gas is discarded. Moreover, in order to release the exhaust gas to the atmosphere, a dedicated exhaust gas treatment facility consisting of a combustion device and a dust collector must be provided, which increases the equipment costs required for the construction of the melting furnace and complicates the operation management of the melting furnace. It has become.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and does not require the provision of a dedicated exhaust gas treatment facility, and can recover the energy of the exhaust gas discharged from the melting furnace. An object of the present invention is to provide a method for treating exhaust gas.

[0007]

The above object is achieved by the following invention.

[0008] The first invention is a method of treating exhaust gas from an incineration residue melting furnace provided in a refuse incineration facility, wherein the exhaust gas generated when the incineration residue is melt-processed in a melting furnace operated in a reducing atmosphere is treated as waste. This is a method for treating exhaust gas from a melting furnace, which is introduced into an incinerator.

According to the present invention, the waste gas from the melting furnace, which contains a large amount of combustible gas such as CO gas and H ₂ gas, is introduced into the waste incinerator, and is mixed with the waste gas and burned. The heat of combustion can be recovered.

According to a second aspect of the present invention, there is provided a method for treating exhaust gas of a melting furnace according to the first aspect, wherein exhaust gas generated when the incineration residue is melted is introduced into an inlet of a secondary combustion chamber of an incinerator. It is.

According to this invention, since the introduction into the inlet portion of the secondary combustion chamber is a portion before the melting furnace exhaust gases secondary combustion takes place, NO _X and CO gas in incineration flue gas, and H ₂ gas the reaction amount of the NO _X to be reduced is increased by a, the concentration of the NO _X in the exhaust gas is reduced.

[0012]

FIG. 1 is a diagram showing an example of an embodiment of a method for treating exhaust gas from a melting furnace according to the present invention. Here, 10 indicates an incinerator and 40 indicates municipal waste. A stoker 12 having a transfer function is provided in a combustion chamber 11 of the incinerator. Reference numeral 14 denotes an intermediate ceiling provided at an upper portion of the combustion chamber for promoting mixing of incineration exhaust gas generated at various points in the combustion chamber. Reference numeral 15 denotes a secondary combustion chamber provided at an upper part of the incinerator, 16 denotes gas cooling equipment such as a boiler and a gas cooler, and 17 denotes an exhaust gas treatment equipment including an acid gas removing device and a dust collector. 25 is a storage tank for incineration residues, 3
Numeral 0 denotes a melting furnace for melting the incineration residue.

The refuse 40 put into the incinerator 10 is ashed through drying, burning and post-combustion processes while being conveyed on the stoker 12, and is discharged as incinerated ash. The incineration ash is sent to the incineration residue storage tank 25. Further, although the incineration exhaust gas generated at various places on the stoker 12 has different compositions, these exhaust gases are mixed at the stage where they flow into the gas mixing section 14 which is the inlet of the secondary combustion chamber, and are subjected to the secondary combustion. It flows into the chamber 15. A gas injection nozzle 18 is provided in the gas mixing section 14 (the inlet of the secondary combustion chamber), and the exhaust gas generated in the melting furnace 30 is injected. An example of the composition of this melting furnace exhaust gas is as shown in Table 1, and contains a large amount of combustible gas such as CO gas and H ₂ gas.

[0014]

[Table 1]

For this reason, the amount of reducing gas such as CO and H ₂ increases in the gas mixing section 14 due to the blowing of the melting furnace exhaust gas, and the NO _x generated in the combustion chamber 11 is increased.
Decrease. Next, the air blowing nozzle 1 provided in the secondary combustion chamber 15 downstream of the gas blowing nozzle 18
From 9 on, secondary combustion air is blown, and complete combustion of exhaust gas is performed. The method of blowing the gas and the secondary combustion air will be described later.

The exhaust gas discharged from the secondary combustion chamber 15 is sent to a gas cooling facility 16 where heat is recovered. The heat-recovered incineration exhaust gas is sent to an exhaust gas treatment facility 17 where it is subjected to a treatment for removing acidic gas such as hydrogen chloride and a dust removal treatment, and then emitted from a chimney. Fly ash collected during the dust removal processing of the exhaust gas treatment equipment 17 is sent to the incineration residue storage tank 25. Incineration residue (incineration ash and fly ash) collected in the incineration residue storage tank 25
Is charged into the melting furnace 30 and subjected to a melting process, and is discharged as a molten slag.

The melting furnace 30 is a closed-type electric resistance type furnace, which generates electric resistance heat by energizing between the electrodes 31 immersed in the melted incineration residue, and the charged incineration residue. Is a furnace that melts. In the melt-processing by the furnace during the heating and melting of incineration residue, CO by decomposition of such unburnt incineration residue, combustible gas (reducing gas) is produced, such as H _X, the furnace reduction It becomes a sexual atmosphere.
This melting furnace exhaust gas is sent to the incinerator as described above.

In the incineration of the refuse and the melting treatment of the incineration residue performed as described above, the entire amount of the exhaust gas generated in the melting furnace 30 is blown into the gas mixing section 14 of the incinerator. Although air is blown into the secondary combustion chamber 15 of the incinerator, a thermometer 20 and an oxygen concentration meter 21 are provided at the outlet of the secondary combustion chamber 15, and based on these measured values, the air is measured. The flow rate of the secondary combustion air blown from the blowing nozzle 19 is controlled. Therefore, the control device 2
2, a secondary combustion air flow control damper 23 and a secondary combustion blower 24 are provided, and the temperature and oxygen concentration of the incineration exhaust gas discharged from the secondary combustion chamber 15 are adjusted to predetermined values. You.

As described above, the exhaust gas from the melting furnace is discharged from the incinerator 10
In this case, there is no need to provide a combustion device dedicated to the melting furnace and an exhaust gas treatment facility such as a dust collector. For this reason, work related to the auxiliary equipment such as monitoring work for misfire of the combustion device is eliminated, and the operation of the melting furnace is facilitated.

In this embodiment, the melting furnace exhaust gas is introduced into the gas mixing section 14 of the incinerator.
No matter where the exhaust gas from the melting furnace is introduced into the incinerator,
The fuel burns at the stage where it flows into the next combustion chamber 15, and the heat of combustion is recovered by the gas cooling facility 16. For this reason, from the viewpoint of energy recovery only, there is no limitation on the location where the melting furnace exhaust gas is introduced. However, when attempting to reduce the NO _X generated in the combustion chamber 11, it is necessary to the melting furnace exhaust gases increase the amount of introduced into the gas mixing portion 14 a reducing gas.

[0021]

According to the present invention, since the exhaust gas of a melting furnace operated in a reducing atmosphere is introduced into a refuse incinerator, the flammable gas such as CO gas and H ₂ gas in the exhaust gas of the melting furnace is reduced to ₂ %.
Combustion occurs in the next combustion chamber, and the heat of combustion is recovered. further,
It is not necessary to provide an exhaust gas treatment facility dedicated to the melting furnace, so that the operation of the melting furnace becomes easy and the construction cost of the waste incineration facility is reduced.

In particular, when the exhaust gas from the melting furnace is introduced into the gas mixing section in the incinerator, CO, H in the gas mixing section is reduced.
Gas such increases _2, the concentration of the NO _X in the exhaust gas is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment according to a method for treating exhaust gas from a melting furnace according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 incinerator 11 combustion chamber 12 stoker 13 intermediate ceiling 14 gas mixing section 15 secondary combustion chamber 16 gas cooling equipment 17 exhaust gas treatment equipment 18 gas injection nozzle 19 air injection nozzle 20 thermometer 21 oxygen concentration meter 22 control device 23 secondary combustion Air flow control damper for secondary use 24 Blower for secondary combustion 25 Storage tank for incineration residue 30 Electric melting furnace 40 Municipal solid waste

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Naoyuki Isozaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 3K061 AA23 AB03 AC01 AC03 BA05 CA11 DA12 DA17 3K065 AB03 AC01 AC03 BA05 HA01

Claims (2)

[Claims] 1. A method for treating exhaust gas from an incineration residue melting furnace provided in a refuse incineration facility, wherein the exhaust gas generated when the incineration residue is melt-processed in a melting furnace operated in a reducing atmosphere is introduced into the refuse incineration furnace. A method for treating exhaust gas from a melting furnace. 2. The method according to claim 1, wherein the exhaust gas generated when the incineration residue is melted is introduced into an inlet of a secondary combustion chamber of the incinerator.