JPS63290314A - Method of processing combustion furnace waste gas - Google Patents

Abstract

PURPOSE:To cause an extremely small amount of harmful organic chlorine compound contained in waste gas to be completely oxidized and decomposed even if a recombustion part is not arranged by a method wherein the waste gas discharged from a combustion furnace is allowed to contact an oxidation catalyst to oxidize and decompose the organic chlorine compound in the waste gas. CONSTITUTION:Waste gas discharged from a combustion furnace for city garbage or for sewage sludge or the like is contacted with oxidization catalyst of platinum catalyst carried on a ceramic carrier or the like at a temperature of 300-900 deg.C to cause organic chlorine compound in the waste gas to be oxidized and decomposed to restrict harmful organic chlorine compound such as dioxine, PCB or the like from being generated. It is possible to oxidize organic chlorine compound such as C6H5Cl, C6H4Cl, C6H3Cl3 or the like in the waste gas by about 85-97% at a temperature higher than 300 deg.C and then at a temperature higher than 400 deg.C, decompose it to CO2 and HCl or the like completely. C6H5Cl, C6H4Cl2 and C6H3Cl3 are important precursors in the reaction course in which halogenation aromatic hydrocarbon such as dioxine, PCB and chlorophenol and the like are generated in the combustion furnace. These substances are oxidized and decomposed and then it is possible to prevent completely harmful substances such as dioxine, PCB and chlorophenol and the like from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for treating incinerator exhaust gas discharged from an incinerator for municipal waste, sewage sludge, etc.

(Conventional technology) SO□, NOx, GO, contained in incinerator exhaust gas,
Regarding harmful substances such as cyanide, removal techniques are being researched and gradually put into practice to protect human health and the environment. However, the dioxins contained in the exhaust gas, P
Research into technology for removing trace amounts of harmful organic chlorine compounds such as CB and chlorophenol has just begun. Generally, in order to completely oxidize and decompose chlorinated organic substances through a combustion process, it is considered necessary to maintain a high temperature of 1000° C. or higher. However, the combustion temperature inside the incinerator is 800-9
Since the temperature is 00°C, it is necessary to further raise the temperature inside the furnace or provide a reburning section in order to oxidize and decompose the organic chlorine compound. However, raising the temperature inside the furnace requires a complete remodeling of the furnace, and at temperatures above 900°C, there is the problem that the ash of the incinerated material will melt and damage the furnace walls. In addition, in stoker furnaces, which are the mainstream of municipal waste incineration, localized low-temperature areas tend to occur in the furnace, so it is necessary to provide a reburning section, but this increases the running cost due to the increase in the total amount of exhaust gas and the reburning fuel. It has the disadvantage of being very large.

(Problems to be Solved by the Invention) The present invention solves the conventional problems as described above, and eliminates the extremely small amount contained in exhaust gas without increasing the combustion temperature in the furnace or providing a reburning section. This was completed with the aim of developing a method for treating incinerator exhaust gas that can completely oxidize and decompose harmful organic chlorine compounds.

(Means for Solving the Problems) The present invention involves bringing exhaust gas emitted from an incinerator, such as municipal waste or sewage sludge, into contact with an oxidation catalyst such as a platinum catalyst supported on a ceramic carrier at a temperature of 300 to 900°C. Oxidatively decomposes organic chlorine compounds in exhaust gas to produce dioxins and PCBs.
It is characterized by suppressing the generation of harmful organic chlorine compounds such as.

The oxidation catalyst used in the present invention is supported on the surface of a ceramic carrier having excellent heat resistance, such as a ceramic honeycomb structure or ceramic pellet, and a typical example is a platinum catalyst. Such a catalyst has a 300 to 90%
Although it is preferable to install the porous filter in a position where it can be contacted at 0° C., it is also possible to use the porous filter itself as a carrier and directly support it on its surface. It can also be installed in the upper part of a fluidized fluidized furnace or stoker furnace to bring it into direct contact with the gas flowing out from the furnace.

As shown in the data of the later examples, such an oxidation catalyst reduces CbHsCI SC&H4Ct' t in the exhaust gas.
, Chll, (1!, etc.) at 300°C.
85-97% at above, completely CO at above 400℃,,
It can be oxidized and decomposed to HCjl etc. This C, 1l
sCl, Cal14CJ z, C611C1,
Dioxins and PCBs are produced in the incinerator.

It is considered to be an important precursor in the reaction pathway in which halogenated aromatic hydrocarbons such as chlorophenol are produced, and by oxidizing and decomposing them, the generation of harmful substances such as dioxins, PCBs, and chlorophenol can be prevented. It can be completely prevented.

Furthermore, from the comparison between the data of the example and the conventional high-temperature combustion method, C
4HSCI, C4HIClz-C4HjClm
In addition to these, dioxins and P
It can be inferred that halogenated aromatic hydrocarbons such as CB and chlorophenol are also easily oxidized and decomposed.

In the present invention, the contact temperature is set to 300°C to 900°C because below 300°C, C6H@C1, C4H4C1
t, the oxidative decomposition rate of Ca1LC1i is 800°C to 850°C
This is because the decomposition rate is lower than that of the normal incineration method, which uses combustion and oxidation decomposition. In addition, if the temperature exceeds 900°C, the support will dissolve and the catalyst will undergo alteration and deterioration.

Next, examples of the present invention will be shown.

(Example) A part of the exhaust gas was sucked into a thermostatic chamber from the exhaust gas line of a sewage sludge incinerator using a suction pump, and brought into contact with a platinum catalyst provided in the thermostatic chamber. A platinum catalyst has platinum supported on the surface of a ceramic honeycomb structure.
iosc z, CaH4Cj! ! , Ca1 mouth 3C
Concentration of ffi3 and ChH5Cl, CaH4 after contact
Cj! E. The concentration of C61hCf3 was measured and the decomposition rate was estimated. The temperature of the thermostatic chamber was gradually changed from 100℃, and CbN
sCl , Ca'+14Cl z , CaH3CI
The results of measuring the decomposition rate of ls are shown in FIG. 1 together with the data when no catalyst is used.

As is clear from the data in Figure 1, simple combustion results in CaH8CJ 5CillnCl□, C1LCj! s
In order to completely oxidize and decompose it, a high temperature of 900°C or higher is required, but in the present invention, a decomposition rate of 85 to 97% was achieved at 300°C, and a decomposition rate of 100% was achieved at 400°C. Note that the SV value in the figure means superficial velocity.

(Effects of the Invention) As is clear from the above description, the present invention utilizes an oxidation catalyst in which exhaust gas from an incinerator is supported on a ceramic carrier.
Cb It sCl by contacting at ~900°C
, ChllaClx, C4H3C1s, etc., and thereby CJsCl, C
! 114C1'z,C&1lsCJ! This has succeeded in preventing the release of harmful organic chlorine compounds such as dioxins, PCBs, and chlorophenols, which are produced using S as precursors, into the atmosphere. In this way, according to the present invention, harmful organic chlorine compounds can be removed at low temperatures, so conventional incinerators can be used as is.
There is no risk of the furnace wall being damaged by molten incineration ash, etc., there is no risk of heavy metals being scattered into the exhaust gas, and there is no need to provide a reburning section, which increases the total amount of exhaust gas and reduces the amount of reburning fuel. Many advantages can be obtained, such as no increase in running costs. Therefore, the present invention greatly contributes to the development of industry as a method for treating incinerator exhaust gas that eliminates the conventional problems.

[Brief explanation of the drawing]

FIG. 1 shows C6I (sCIt −
It is a graph showing the relationship between the decomposition rate and contact temperature of ChHaC12z and C&HtC13. Patent applicant: Nippon Insulators Co., Ltd. Representative: Akira Shima, Tatsu Watatsu, Likai
Yama Rei Bun Huo Figure 1 Stem nl [°go]

Claims (1)

[Scope of Claims] 1. An oxidation catalyst such as a platinum catalyst in which exhaust gas from an incinerator for municipal waste, sewage sludge, etc. is supported on a ceramic carrier; and 3.
A method for treating incinerator exhaust gas, characterized in that organic chlorine compounds in the exhaust gas are oxidized and decomposed by contact at 00 to 900°C, thereby suppressing the generation of harmful organic chlorine compounds such as dioxins and PCBs. 2. Organic chlorine compounds that undergo oxidative decomposition are mainly C_6H_
5Cl, C_6H_4Cl_2, C_6H_3Cl_3
The method for treating incinerator exhaust gas according to claim 1, which is a halogenated aromatic hydrocarbon such as .