JPH10281422A - Melting treatment method and apparatus for refuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent ash of pyrolysis carbon from being scattered to a heat recovery device and reduce contents of NOX and hazardous materials of chlorinated organic compounds in a combustion exhaust gas, in an incineration treatment of refuse wherein waste such as municipal refuse is burned and melted. SOLUTION: Pyrolysis carbon and pyrolysis gas are successively burned in furnaces arranged in a multiple of stages and because the pyrolysis gas is burned at an air ratio of 1 or less, hydrocarbon radicals such as H2 , CO, NHn , HCN, CHn and the like exist in combustion exhaust gas, and these chemical species reduce NOX produced when the pyrolysis carbon is burned at a high temperature at an air ratio of 1 or higher and thus the NOx content in the exhaust gas can be reduced. By introducing air into the combustion exhaust gas in an incomplete combustion state of an air ratio of 1 or less, complete combustion is realized and chlorinated organic compounds in the exhaust gas can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for incinerating waste such as municipal waste.

[0002]

2. Description of the Related Art Conventional waste incinerators include a stoker-type incinerator in which waste is put into a lattice stage provided at the lower part of a combustion furnace and burned on the lattice stage, or a fluid medium (a fluid medium held on a hearth). 700-80 fluidized (usually using sand particles)
Fluidized bed furnaces are used in which incinerators are put into a 0 ° C bed and the incinerators are burned in the bed, but the incinerated ash burns irons such as empty cans in the waste. And the volume reduction is insufficient. Therefore, in order to reduce the volume, there is a direct melting treatment method in which waste is melted at a temperature close to 2000 ° C. However, iron in empty cans in incinerated ash is oxidized, aluminum is melted, and resources cannot be used effectively. In order to melt the problem or waste to a high temperature, it was necessary to add fuel such as coke or to use electric power by using plasma.

[0003] In recent years, for example, a gas melting method disclosed in Mitsui Engineering & Shipbuilding Technical Report No. 151 (February 1994) has been reported from the viewpoint of resource recycling and thermal recycling of iron, aluminum and the like. In this method, as shown in FIG. 2, waste is thermally decomposed into pyrolysis gas and pyrolysis carbon using a pyrolysis drum 19 in an atmosphere in which oxygen at about 450 ° C. is cut off.
Solid-gas separation device 3 for generated pyrolysis gas and pyrolysis carbon
The pyrolysis gas is separated into pyrolysis carbon and pyrolysis carbon by the pyrolysis gas supplied to the melting furnace 20 by a pyrolysis gas pipe 13 connecting the solid-gas separation device 3 and the melting furnace 20, while iron, aluminum, Non-combustible components such as rubble and pyrolytic carbon containing a large amount of ash are cooled and separated into incombustible components such as iron and aluminum by the non-combustible material separation device 4 and then supplied to the melting furnace 20 through the pyrolytic carbon pipe 14. The pyrolysis gas burner 16 and the pyrolysis carbon burner 11 at the top of the melting furnace 20 allow the melting furnace 20
It burns at a temperature of about 1300 ° C. At this time, the ash contained in the pyrolytic carbon is melted in the melting furnace 20, and the molten ash falls into the slag tap 10 from the furnace bottom of the melting furnace 20 and is collected as rapidly cooled and solidified granulated slag. Further, the exhaust gas from the melting furnace 20 is heat-exchanged with the air for thermal decomposition of the thermal decomposition drum 19 in the heat exchanger 22, further sent to the heat recovery device 7, heat exchanged, and unburned in the dust collection device 8. After the matter and the slag that have been scattered are collected, the exhaust gas processing device 9 uses a harmful substance in the exhaust gas, for example,
This method removes hydrogen chloride gas, heavy metals, and the like. Also,
In this way, in order to reduce of the NO _x generated during combustion of the pyrolysis gases and pyrolytic carbon, supplied squeezing combustion air amount from the air blowing device 21a provided at the furnace top of the melting furnace 20, excess fuel to reduce NO _x by burning, further blown downstream air melting furnace 20 21
b, it adopts a method of a fuel lean combustion by blowing combustion air, i.e. a multi-stage combustion system, known as NO _x reduction technologies from 21c.

[0004]

The above-mentioned Mitsui Engineering & Shipbuilding Technical Report No. 1
In the method for reducing NO _x in the waste melting method reported in No. 51, a sufficient reduction area for reducing and burning the pyrolysis gas and pyrolytic carbon simultaneously blown from the top of the melting furnace is secured. Since it is necessary to secure a sufficient complete combustion region for complete combustion after the second stage combustion, the melting furnace becomes large.

An object of the present invention is to prevent ash in pyrolytic carbon from being scattered to a heat recovery device, and to prevent NO in a combustion exhaust gas of pyrolytic carbon and pyrolysis gas in a combustion melting furnace.
It is an object of the present invention to provide a method and an apparatus for reducing harmful substances such as x and organic chlorine compounds.

[0006]

The means of the present invention for solving the above problems are as follows. (1) A method for melting waste by heating waste such as municipal waste and supplying the generated pyrolysis gas and pyrolysis carbon together with air to a melting furnace to perform melting processing, wherein the pyrolysis carbon is used in an air ratio. A method for melting wastes, comprising burning at least one combustion exhaust gas and the generated pyrolysis gas at an air ratio of 1 or less to contact the generated combustion exhaust gas. (2) burning the pyrolytic carbon at an air ratio of 1 or more,
Melting the waste gas by burning the generated combustion exhaust gas and the pyrolysis gas at an air ratio of 1 or less, contacting the generated combustion exhaust gas, and then blowing air into the mixed combustion exhaust gas for combustion. Processing method. (3) burning the pyrolytic carbon at an air ratio of 1 or more;
Depending on the concentration of NO _x in combustion exhaust gas produced, a melt processing method for waste and controlling the air ratio for burning the pyrolysis gas. (4) burning the pyrolytic carbon at an air ratio of 1 or more,
The air blown to burn the mixed flue gas according to the CO concentration in the mixed flue gas after contacting the generated flue gas and the flue gas obtained by burning the pyrolysis gas at an air ratio of 1 or less. This is a method for melting and processing waste, characterized in that the amount is controlled. (5) A pyrolysis furnace for heating waste such as municipal waste and pyrolyzing it into pyrolysis gas and pyrolysis carbon, and a melting furnace for burning and melting the generated pyrolysis gas and pyrolysis carbon together with air. In the apparatus for melting and processing waste, at least, the melting furnace, at least, a pyrolysis carbon combustion furnace that burns pyrolytic carbon with air, a combustion furnace that burns pyrolysis gas and a pyrolysis carbon combustion furnace And a discharge pipe for discharging combustion exhaust gas to a pyrolysis gas combustion furnace. (6) A waste melting treatment device comprising a heat recovery device provided with an air blowing device and a discharge pipe for discharging exhaust gas from a pyrolysis gas combustion furnace to the heat recovery device.

In the present invention, pyrolysis carbon and pyrolysis gas are sequentially burned in a multi-stage furnace. Since the pyrolysis gas is burned under a combustion condition of an air ratio of 1 or less, H _{2 is} contained in the combustion exhaust gas. _{, CO, NH n, HCN,} CH hydrocarbon radicals are present, such as _m, NO _x which these species are generated when the pyrolytic carbon is burned in one or more hot air ratio
Was reduced, it is possible to reduce the concentration of NO _x in the exhaust gas. Further, by injecting air into combustion exhaust gas having an air ratio of 1 or less in an incomplete combustion state, complete combustion can be achieved, and organic chlorine compounds in the exhaust gas can be reduced.

[0008]

FIG. 1 shows an embodiment of an apparatus for carrying out the method of the present invention. This apparatus heats waste such as municipal waste and pyrolyzes it into pyrolysis gas and pyrolysis carbon. Melt that burns and melts the generated pyrolysis gas and pyrolysis carbon together with air. A melting furnace for waste provided with a furnace, wherein the melting furnace burns and melts pyrolytic carbon together with air;
And a pyrolysis gas combustion furnace 6 for burning the pyrolysis gas, and a combustion exhaust gas from the pyrolysis carbon combustion furnace 5
A heat recovery device 7 further provided with an air supply device 18 and a discharge tube 2 for discharging exhaust gas of the pyrolysis gas combustion furnace 6 to the heat recovery furnace 7 are provided.
5 is provided. Incidentally, provided concentration of NO _x analyzer 24 for analyzing the concentration of NO _x, the discharge pipe 25 is CO concentration analyzer 26 for analyzing the CO concentration is provided in the discharge pipe 23.

As the pyrolysis furnace 2, a shaft furnace, a stoker furnace, a fluidized bed furnace, or the like used in a conventional refuse incinerator can be applied. In addition, a conventional waste pulverizer 1 is provided at a stage preceding the pyrolysis furnace 2, a solid-gas separation device 3 for separating pyrolysis gas and pyrolysis carbon is provided at a later stage, and An incombustible material separation device 4 for separating incombustible materials is provided. An exhaust gas dust collecting device 8 is provided downstream of the heat recovery device 7, and an exhaust gas processing device 9 is provided downstream of the heat recovery device 7.

The pyrolytic carbon combustion furnace 5 has a burner 11 for burning pyrolytic carbon on the side and a slag tap 1 on the bottom.
The combustion furnace 11 is provided with a pyrolysis carbon pipe 14 for supplying pyrolysis carbon after incombustible substance separation from the incombustible substance separation device 4 to the combustion burner 11, and combustion air for supplying air. The supply pipe 12 is connected.

The pyrolysis gas combustion furnace 6 is a cylindrical furnace having a burner 16 for burning pyrolysis gas on the side thereof.
The combustion burner 16 is connected to a pyrolysis gas pipe 13 for supplying a pyrolysis gas after the pyrolysis carbon is separated from the solid-gas separation device 3 and an air supply pipe 17 for supplying air.

Between the pyrolysis carbon combustion furnace 5 and the pyrolysis gas combustion furnace 6, a discharge pipe 23 for discharging the combustion exhaust gas of the pyrolysis carbon combustion furnace 5 to the pyrolysis gas combustion furnace 6 is provided. In the present embodiment, an exhaust pipe 23 is formed by connecting an exhaust gas outlet at the top of the pyrolysis carbon combustion furnace 5 and a bottom of the pyrolysis gas combustion furnace 6, and the combustion furnaces are stacked in two stages, and the space between them is discharged. They are connected by a tube 23 to form an integral furnace. Not limited to this example, both furnaces may be provided independently, and the space between them may be connected by piping. The discharge pipe 23, concentration of NO _x analyzer 24 for measuring the concentration of NO _x in the pyrolytic carbon combustion exhaust gas
Is provided.

A heat recovery device 7 is provided downstream of the pyrolysis gas combustion furnace 6, and is connected to an outlet of the pyrolysis gas combustion furnace 6 by a discharge pipe 25. In this embodiment,
A discharge pipe 25 is formed by connecting an upper discharge port of the pyrolysis gas combustion furnace 6 with a bottom of the heat recovery device 7. The discharge pipe 25 is provided with a CO concentration analyzer 26 for measuring the CO concentration in the combustion exhaust gas discharged from the pyrolysis gas combustion furnace. An air supply device 18 is provided near the combustion exhaust gas inlet of the heat recovery device 7. In this embodiment, the air supply device 18 is provided in the heat recovery device 7, but may be provided in the discharge pipe 25.

Therefore, as in the present embodiment, the pyrolysis carbon combustion furnace 5, the pyrolysis gas combustion furnace 6, and the heat recovery device 7
It may be constituted by being stacked in stages and connected by discharge pipes 23 and 25 to be integrally formed. Alternatively, the pyrolysis carbon combustion furnace 5 and the pyrolysis gas combustion furnace 6 may be provided independently and connected between them by piping. May be.

The waste is pulverized by a pulverizer 1 and charged into a pyrolysis furnace 2. The waste is heated and thermally decomposed in the pyrolysis furnace 2, and the organic matter in the waste is decomposed into pyrolytic carbon and pyrolysis gas, and separated by the solid-gas separation device 3 into pyrolysis carbon and pyrolysis gas.

The separated pyrolytic carbon containing incombustibles and ash is separated from incombustibles such as iron, aluminum and rubble by an incombustibles separator 4 and then burned from a pyrolytic carbon combustion furnace 5 through a pyrolytic carbon pipe 14. The fuel is burned at a high temperature of 1300 ° C. or more in the pyrolysis carbon combustion furnace 5 together with the air supplied from the air supply pipe 12 so as to have an air ratio of 1 or more. In the present embodiment, the pyrolytic carbon combustion air is supplied from the air supply pipe 12 of the burner 11 that supplies the pyrolytic carbon. However, an air blowing device is provided separately from the burner 11 to supply the pyrolytic carbon combustion air. It is also possible. The ash in the pyrolytic carbon melts and falls into the water from the slag tap 10 to become granulated solids. The collected granulated solid can be effectively used as a raw material for cement and a material for civil engineering and construction. The combustion exhaust gas in the pyrolytic carbon combustion furnace 5 contains NO _x and the exhaust pipe 2
3 is discharged to a pyrolysis gas combustion furnace 6.

On the other hand, the pyrolysis gas is sucked from the pyrolysis gas pipe 13 by the fan 15 and supplied to the pyrolysis gas combustion furnace 6. In the pyrolysis gas combustion furnace 6, the pyrolysis gas generated in the pyrolysis furnace 2 is supplied to the burner 16, and air is supplied from the air supply pipe 17.
Burn at high temperature of 0 ° C or higher At this time, according to the detection value of the NO _x concentration analyzer 24 provided in the discharge pipe 23, for example, when the NO _{x is} 200 ppm, the air ratio is 0.8, and the NO _x :
At 300 ppm, it is preferable that air having an air ratio controlled such as 0.6 is supplied from the air supply pipe 17 and the pyrolysis gas is burned at a high temperature of 1300 ° C. or more. In this embodiment, the pyrolysis gas combustion air is supplied from the air supply pipe 17 of the burner 16 that supplies the pyrolysis gas. However, an air blowing device is provided separately from the burner 16 to supply the pyrolysis gas combustion air. It is possible to Since the pyrolysis gas is burned in the pyrolysis gas combustion furnace 6 at an air ratio of 1 or less,
The combustion exhaust gas of the pyrolysis gas in the pyrolysis gas combustion furnace 6 contains H
_{2, CO, NH n, HCN} , hydrocarbons radicals such as CH _m exists. This pyrolysis gas combustion exhaust gas and the NO discharged from the pyrolysis carbon combustion furnace 5 supplied from the discharge pipe 23
_By mixing the pyrolysis gas flue gas containing _x , H ₂ , CO, NH _n ,
HCN, hydrocarbon radical such as CH _m is to reduce NO _x in the pyrolytic carbon combustion exhaust gas, it is possible to reduce the NO _x in the exhaust gas. The combustion exhaust gas is discharged to the heat recovery device 7 through the discharge pipe 25.

Since the flue gas discharged from the pyrolysis gas combustion furnace 6 is mixed with the flue gas burned under a combustion condition having an air ratio of 1 or less, an incomplete combustion may generate an organic chlorine compound. Therefore, the air supply device 18 is provided in the heat recovery device 7, and the air is supplied from the air supply device 18 to the combustion exhaust gas, whereby the unburned components in the combustion exhaust gas are completely burned and the generation of the organic chlorine compound is suppressed. It becomes possible. The air introduced into the flue gas is discharged from the exhaust pipe 2
It is preferable that the flow rate is controlled so that the combustion exhaust gas is completely burned according to the detection value of the CO concentration analyzer 26 provided in 5, and the combustion exhaust gas is supplied to the air supply device 18. A waste heat boiler or the like can be used for the heat recovery device 7 in the flue gas to recover waste heat in the flue gas, and the recovered steam can be used for a heat source or power generation.

The dust collector 8 collects unburned components and the like with a device such as a bag filter. The exhaust gas treatment device 9 removes harmful substances, for example, heavy metals and the like, in the exhaust gas using a washing tower or the like. As these devices, those used in existing garbage incinerators can be applied.

[0020]

Next, an embodiment of the present invention using the apparatus of the present invention shown in FIG. 1 will be described. Waste is treated as 4.2 T / H of municipal waste. In municipal waste, in addition to combustible materials, empty cans, empty bottles,
In addition to containing 8% non-combustible substances such as rubble, flammable substances also contain 9% ash. Waste is 200m with crusher 1
m or less and charged into the pyrolysis furnace 2,
Pyrolysis gas generated at 200 Nm ³ / h, temperature 450 ° C
Was supplied to the pyrolysis gas combustion furnace 6 through the solid-gas separator 3 and the pyrolysis gas pipe 13. The fan 14 for increasing the pressure of the pyrolysis gas increased the pressure of the pyrolysis gas at 450 ° C., so that a special heat-resistant fan was not used. On the other hand, the pyrolysis carbon generated in the pyrolysis furnace 2 is separated from the pyrolysis gas by the solid-gas separation device 3, and the incombustible separation device 4 separates 680 kg of pyrolysis carbon of ash separated from incombustible substances such as iron and aluminum. / H,
The temperature of 50 ° C. was supplied to the pyrolysis carbon combustion furnace 5.

In the pyrolytic carbon combustion furnace 5, the burner 11
And the air supplied from the air supply pipe 12 were burned at an air ratio of 1.3. The temperature of the combustion exhaust gas at the exit side of the pyrolytic carbon combustion furnace 5 was 1400 ° C., and the NO _x concentration in the exhaust gas was 200 ppm.
The ash in the pyrolytic carbon melted to form granulated solids from the slag tap 10, and no ash was present in the flue gas.

In the pyrolysis gas combustion furnace 6, the air ratio is controlled by the pyrolysis gas supplied to the burner 16 and the detection value from the NO _x concentration analyzer 24, and the air supplied from the air supply pipe 17 is converted to the air ratio. Burned at 0.8. Flue gas temperature of the pyrolysis gas combustion furnace 6 the outlet is 1400 ° C., NO _x concentration in the exhaust gas is 45 ppm, organochlorine compounds concentration was 10000 ng / Nm ^3.

In the heat recovery unit 7, air 4500 Nm 3 / air whose flow rate is controlled by the detection value from the CO concentration analyzer 26 is used.
h was supplied from the air supply device 18 to the combustion exhaust gas discharged from the pyrolysis gas combustion furnace 6. The concentration of organic chlorine compounds in the exhaust gas at the outlet side of the heat recovery device 7 is 0.1 to 0.2 ng / N.
m ³ .

[0024]

According to the present invention, pyrolysis carbon and pyrolysis gas are sequentially burned in a multistage furnace, but H ₂ , C generated when the pyrolysis gas is burned at an air ratio of 1 or less.
O, NH _n, HCN, CH Since hydrocarbon radical such as _m causes a pyrolytic carbon reduced the NO _x to be generated when burned in air ratio of 1 or more of high temperature, NO _x efficiently in the exhaust gas
Can be reduced. Further, by injecting air into combustion gas in an incomplete combustion state having an air ratio of 1 or less, complete combustion is achieved, and it becomes possible to reduce the amount of organic chlorine compounds in exhaust gas.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a waste incinerator according to the present invention.

FIG. 2 is a diagram showing a conventional gas melting type waste incinerator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Crusher 2 Pyrolysis furnace 3 Solid-gas separation apparatus 4 Non-combustible substance separation apparatus 5 Pyrolysis carbon combustion furnace 6 Pyrolysis gas combustion furnace 7 Heat recovery device 8 Dust collection device 9 Exhaust gas treatment device 10 Slag tap 11 Burner 12 Pyrolysis carbon Combustion air supply pipe 13 Pyrolysis gas pipe 14 Pyrolysis carbon pipe 15 Fern 16 Burner 17 Pyrolysis gas combustion air supply pipe 18 Air supply device 19 Pyrolysis drum 20 Melting furnace 21a Air blowing device 21b Air blowing device 21c Air blowing 22 heat exchanger 23 exhaust pipe 24 NO _x concentration analyzer 25 discharge pipe 26 CO concentration analyzer

Claims (6)

[Claims] 1. A waste melting method for heating waste such as municipal solid waste and supplying the generated pyrolysis gas and pyrolysis carbon together with air to a melting furnace to perform a melting process. A method for melting waste, comprising: burning a combustion exhaust gas generated by burning at an air ratio of 1 or more, and burning the pyrolysis gas at an air ratio of 1 or less to contact the generated combustion exhaust gas. 2. Combustion of the pyrolytic carbon at an air ratio of 1 or more, combustion of the generated combustion exhaust gas at an air ratio of 1 or less, and contact of the generated combustion exhaust gas with the generated combustion exhaust gas. The method for melting waste according to claim 1, wherein air is blown into the combustion exhaust gas for combustion. Wherein the combustion of the pyrolytic carbon by an air ratio of 1 or more, depending on the concentration of NO _x in combustion exhaust gas produced, claims, characterized in that to control the air ratio to burn the pyrolysis gas The method for melting waste according to 1 or 2. 4. The mixed combustion exhaust gas after the pyrolysis carbon is burned at an air ratio of 1 or more, and the generated combustion exhaust gas is brought into contact with the combustion exhaust gas obtained by burning the pyrolysis gas at an air ratio of 1 or less. 3. The method according to claim 2, wherein the amount of air blown to burn the mixed flue gas is controlled according to the CO concentration of the waste gas. 5. A pyrolysis furnace for heating waste such as municipal garbage and pyrolyzing it into pyrolysis gas and pyrolysis carbon, and a melting furnace for burning and melting the generated pyrolysis gas and pyrolysis carbon together with air. In a device for melting and processing wastes comprising at least a furnace, the melting furnace, at least, a pyrolytic carbon combustion furnace that burns pyrolytic carbon with air,
A waste melting apparatus comprising: a combustion furnace for burning a pyrolysis gas; and an exhaust pipe for discharging combustion exhaust gas from a pyrolysis carbon combustion furnace to a pyrolysis gas combustion furnace. 6. The waste melting apparatus according to claim 5, further comprising a heat recovery device having an air blowing device, and a discharge pipe for discharging exhaust gas from the pyrolysis gas combustion furnace to the heat recovery device.