JPH11248135A - Municipal waste incinerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive the effective utilization as well as the stabilization of operation of a municipal waste incinerating facility by a method wherein exhaust gas from an incinerating furnace after removing dust and exhaust gas from an ash melting furnace, which is passed through a CO gas incinerating device, are joined to treat the joined gas through a wet type exhaust gas treating device. SOLUTION: Exhaust gas 42, discharged out of an incinerating furnace 1, is cooled by a gas cooler 3 to a temperature, suitable to a bag filter 4 at the downstream, and dust in the exhaust gas is removed by the bag filter 4. CO gas, generated by the oxidizing of a main electrode, is contained in exhaust gas discharged out of an ash melting furnace 19 since carbon is employed as the main electrode and, therefore, the exhaust gas is burnt by a CO gas burning device 26 and, thereafter, is joined with the exhaust gas 42 of the incinerating furnace 1, which is discharged out of the bag filter 4. The joined exhaust gas 44 is treated by a wet type exhaust gas treating device whereby dust or harmful gas, contained in the exhaust gas 43 from the ash melting furnace 19, as well as harmful gas or the gas of a heavy metal, contained in the exhaust gas 42 from the incinerating furnace 1, are removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a municipal solid waste incinerator, and more particularly to a municipal solid waste incinerator provided with a melting furnace for incinerated ash and fly ash discharged from a refuse incinerator.

[0002]

2. Description of the Related Art Various wastes such as municipal solid waste and sewage sludge have been incinerated in an incineration facility, and the resulting incinerated ash and dust have conventionally been disposed of in landfills. However, due to the problem of depletion of landfill sites and the problem of groundwater contamination due to elution of harmful heavy metals, the necessity for weight reduction, volume reduction, and detoxification by melting is increasing.

[0003] Under such a background, a melting treatment method using a residual carbon in ash, coke, kerosene, and electric power as a heat source has been proposed.
Actual processing is performed in part. Among them, there are a plasma arc heating method and a resistance heating method as a melting furnace using electric power as a heat source.

The resistance heating type ash melting furnace has a counter electrode disposed in a melting slag and heats and melts the ash by electric resistance heat (Joule heat) caused by direct current or alternating current.
It is characterized by 1) high thermal efficiency, 2) little generated gas, 3) no flicker due to no arc generation, and 4) separate slag that separates molten slag and molten metal.

FIG. 2 shows a flow sheet of a municipal solid waste incinerator having an ash melting furnace. In FIG. 2, 1 is an incinerator, 2
1 is a generator, 19 is a DC electric resistance type ash melting furnace, together with its auxiliary equipment, incineration facilities, power generation facilities,
Constructs an ash melting furnace. The incinerator 1 is illustrated as a stoker-type incinerator.

[0006] Among the incineration facilities, 22 is a garbage pit, which stores the received garbage and sequentially puts it into the incinerator 1 for incineration. The generated exhaust gas is boiler 2,
Water injection type gas cooler 3, bag filter 4, induction blower 5
And discharged from the chimney 6. Dust (fly ash) in the exhaust gas is removed by the bag filter 4 and the collected soot is stored in a soot storage tank 8 by a soot transfer conveyor 7. Incineration ash generated during incineration,
Boiler ash and the like are collected in a dry ash removal device 9, guided by a magnetic separator 11 and a vibrating sieve 12 by an ash transfer conveyor 10 to remove iron 13 and bulky materials 14, and then transferred to the ash transfer conveyor 1.
5 is stored in the incineration ash storage tank 16.

[0007] In the power generation facility 20, heat generated by the incineration process is recovered by the boiler 2, converted into power by a cycle composed of the boiler 2, turbine, condenser, and condensate tank, and further converted into power by the generator 21. Converting. The generator 21 is operated in parallel with an external power system, and the electric power is supplied to the incinerator 1 or the melting furnace 19.
Power is supplied to

[0008] In the ash melting facility, ash is cut out from the dust storage tank 8 and the incinerated ash storage tank 16, and the ash is supplied to the ash supply conveyor 17.
Is supplied to an ash melting furnace 19 through an ash hopper 18. The ash is melted in an ash melting furnace 19 to become a molten sludge 23, which is cooled and stored in a sludge storage tank 24. 25 is a metal storage tank. Since the ash gas discharged from the ash melting furnace 19 contains CO gas, the ash gas is processed by the CO gas combustor 26 and then discharged from the chimney 6 through the dust collector 4a such as a bag filter and the induction blower 5a. Is done.
In some cases, the exhaust gas of the ash melting furnace 19 may be used as the secondary combustion gas of the refuse incinerator 1 without passing through the CO gas combustor 26. Instead of the stoker-type incinerator 1, a fluidized-bed incinerator may be used.

[0009]

The amount of exhaust gas generated from the incinerator 1 is about 5000 m ³ / t per refuse weight,
The amount of fly ash contained therein is 2 to 5 g / m ³ , and the amount of incinerated ash generated from the incinerator 1 and the amount of fly ash are about 100 kg / t per refuse weight. On the other hand, when the 100 kg of ash is melted, the amount of exhaust gas generated is about 20 m ³ , and the amount of fly ash contained in the exhaust gas is 150 to 200
g / m ³ . According to FIG. 2, in the municipal solid waste incinerator having the ash melting furnace 19 described above, the exhaust gas from the incinerator 1 and the exhaust gas from the ash melting furnace 19 are separately separated and then discharged to the outside.

The exhaust gas discharged from the incinerator 1 contains trace amounts of harmful gases such as hydrogen chloride (HCl), SOx and NOx and trace amounts of heavy metals such as cadmium, chrome and mercury, in addition to fly ash. . If these exceed the regulation values, a device for removing harmful gases and heavy metals other than dust removal is required. On the other hand, when the ash melting furnace 19 is of a DC electric resistance type, in which the alkali salt such as salt contained in the ash is actively electrolyzed to prevent the deterioration of the furnace wall due to the alkali salt, Since a large amount of harmful gases such as hydrogen chloride are generated, dry type dust removers such as bag filters are not suitable. Japanese Patent Application No. 8-1422631, "Exhaust gas treatment device for ash melting furnace"
And a wet exhaust gas treatment apparatus disclosed in Japanese Patent Application No. 8-146124, "Exhaust Gas Absorption Device for Ash Melting Furnace". FIG. 3 is a flow sheet of a pilot plant of an ash melting furnace and an exhaust gas treatment apparatus disclosed in the 7th Annual Meeting of the Society of Waste Management, Proceedings of 1996, showing the contents of the invention.

Under these circumstances, the treatment of the exhaust gas from the incinerator 1 and the exhaust gas from the ash melting furnace 19 separately and exhausting them to the outside is because of the effective use of the equipment and the stabilization of the operation. I can not afford to be disadvantaged.

The present invention has been made in view of the above-mentioned problems of the prior art.
By integrating the treatment of exhaust gas from
It is an object of the present invention to provide a municipal solid waste incinerator capable of effectively utilizing equipment and stabilizing operation.

[0013]

Means for Solving the Problems To achieve the above object, a municipal solid waste incinerator according to the present invention comprises: a municipal solid waste incinerator;
An exhaust gas boiler for treating exhaust gas from the incinerator;
A gas cooler and a bag filter, and a DC electric resistance type ash melting furnace for melting and processing incineration ash and an exhaust gas boiler from the incinerator and fly ash from the gas cooler and the bag filter.
The exhaust gas from the bag filter and the exhaust gas from the ash melting furnace are combined after passing through a CO gas combustor, and a wet exhaust gas treatment device, a gas heater and a NOx decomposing contact tower for processing and discharging the exhaust gas to the outside. It is provided.

Next, the operation of the present invention will be described. Exhaust gas discharged from the incinerator is cooled by a gas cooler to a temperature suitable for a downstream bag filter after heat energy is recovered by an exhaust gas boiler, and is removed by the bag filter. The incineration ash generated in the incinerator and the fly ash removed by the bag filter or the like are sent to an ash melting furnace and melted. Since the exhaust gas discharged from the ash melting furnace contains CO gas, it is burned by a CO gas combustor, and then combined with the exhaust gas from the incinerator discharged from the bag filter. The combined exhaust gas is suctioned by the gas absorption tower system that sprays the absorbing liquid to adsorb dust and soluble components, and the suction effect of the jet flow of the absorbing liquid absorbs the dust and soluble components into the absorbing solution. Dust, hydrogen chloride, sulfur, etc.
Hazardous gases such as Ox and heavy metal gases are removed. Since NOx is not sufficiently removed by the wet exhaust gas treatment device,
The exhaust gas is heated by the gas heater to a temperature suitable for the downstream NOx decomposition catalyst tower, and then passes through the catalyst tower,
NOx is removed and discharged outside through a chimney.

As described above, a wet type exhaust gas treatment apparatus suitable for exhaust gas treatment of a dc melting furnace of a DC electric resistance type in which electrolysis of salt and the like in the ash is actively performed during the melting of the ash is provided by using the exhaust gas and the ash of the incinerator. Since it is used for the treatment of the mixed gas with the exhaust gas from the melting furnace, the effective use of the equipment and the stabilization of the operation can be achieved as compared with the case where both are treated separately.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flow sheet of the municipal solid waste incinerator of the present invention. In this figure, the same parts as those of the conventional municipal solid waste incinerator shown in FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted. In FIG. 1, reference numeral 30 denotes a wet exhaust gas treatment device,
1 is a gas heater and 32 is a NOx decomposition catalyst tower. 4
5 is municipal waste, and 46 is drainage. As shown in the figure, the municipal solid waste incinerator of the present invention comprises an municipal solid waste incinerator 1, an exhaust gas boiler 2 for treating exhaust gas 42 from the incinerator 1,
A DC electric resistance ash melting furnace 19 for melting and processing the gas cooler 3 and the bag filter 4, the incineration ash 40 from the incinerator 1 and the fly ash 41 from the exhaust gas boiler 2, the gas cooler and the bag filter 4; Exhaust gas 42 from bag filter 4
And the flue gas 43 from the ash melting furnace 19 are combined after passing through the CO gas combustor 26, and are processed and discharged to the outside by the wet-type flue gas treatment device 30, the gas heater 31, and N
An Ox decomposition catalyst tower 32 is provided.

The municipal solid waste incinerator 1 may be a stoker type as shown in FIG. 2, but may be a fluidized bed type or a rotary type. The bag filter 4 is a filtration type dust collector, but is not limited thereto, and may be an electric dust collector. The wet exhaust gas treatment device 30 may be of an absorption tower type in which the absorbent is dropped in a spray form from the upper part of the tower and comes into contact with the exhaust gas 44 flowing from the lower part of the tower toward the upper part of the tower to absorb dust and harmful gas. A jet scrubber type in which the absorbent and the exhaust gas are brought into contact with each other by utilizing the suction action of the jet stream may be used. The gas heater 31 is a heat exchanger that raises the temperature to a temperature (250 to 300 ° C.) suitable for the NOx decomposition catalyst tower 32 provided downstream. The NOx decomposition catalyst tower 32 is used to reduce NOx into nitrogen and water using ammonia as a reducing agent, and is provided in the tower, and allows the exhaust gas 44 to pass through a ceramic honeycomb supporting a catalyst.

Next, the operation of the present embodiment will be described. The exhaust gas 42 discharged from the incinerator 1 is recovered by the exhaust gas boiler 2 and then cooled by the gas cooler 3 to a temperature suitable for the downstream bag filter 4. As the gas cooler 3, a water injection type is usually used. The exhaust gas 42 that has exited the gas cooler 3 is removed by the bag filter 4. The incinerated ash 40 generated in the incinerator 1 and the fly ash 41 generated in the exhaust gas boiler 2, the gas cooler 3, and the bag filter 4 are all sent to the ash melting furnace 19, where they are melted by direct current and melted. Discharged as 23. Since the exhaust gas discharged from the ash melting furnace 19 uses carbon as a main electrode and contains CO gas generated by oxidizing the carbon, the CO gas is combusted by the CO gas combustor 26. After that, it is combined with the exhaust gas 42 from the incinerator 1 discharged from the bag filter 4. The combined exhaust gas 44 is subjected to dust and harmful gas contained in the exhaust gas 43 from the ash melting furnace 19 and the exhaust gas 42 from the incinerator 1 by a wet exhaust gas treatment device.
The harmful gas and heavy metal gas contained in the gas are removed. The exhaust gas 44 exiting the wet exhaust gas treatment device 30 has a temperature of 100
° C, the gas heater 31
After being heated to 300 ° C. and sent to the NOx decomposition catalyst tower 32 to remove NOx, it is discharged to the outside through the chimney 6.

As described above, the wet exhaust gas treatment apparatus 30 suitable for exhaust gas treatment of the DC electric resistance type ash melting furnace 19 in which electrolysis of salt and the like contained in ash is actively performed during ash melting,
Since it is used for the treatment of the mixed gas 44 of the exhaust gas 42 of the incinerator 1 and the exhaust gas 43 of the ash melting furnace 19, both can be effectively used and the operation can be stabilized as compared with the case where both are used separately.

The present invention is not limited to the embodiments described above, and various changes can be made without departing from the gist of the invention.

[0021]

As described above, the municipal solid waste incinerator according to the present invention is characterized in that the exhaust gas from the incinerator after dust removal and C
Since the waste gas from the ash melting furnace that passed through the O gas incinerator was merged and treated by the wet exhaust gas treatment device,
It has excellent effects such as effective utilization of equipment and stabilization of operation.

[Brief description of the drawings]

FIG. 1 is a flow sheet of the municipal solid waste incinerator of the present invention.

FIG. 2 is a flow sheet of the conventional municipal solid waste incinerator.

FIG. 3 is a flow sheet of a pilot plant of an ash melting furnace and an exhaust gas treatment device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Municipal waste incinerator 2 Exhaust gas boiler 3 Gas cooler 4 Bag filter 19 Ash melting furnace 30 Wet exhaust gas treatment apparatus 31 Gas heater 32 NOx decomposition catalyst tower

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hideki Iwata 2-1-1 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Tokyo 1st Factory (72) Inventor Toshiyuki Suzuki 2-1-1 Toyosu, Koto-ku, Tokyo No. 1 Ishikawajima Harima Heavy Industries Co., Ltd. Tokyo 1st factory

Claims (1)

[Claims] 1. An incinerator for municipal solid waste, an exhaust gas boiler, a gas cooler and a bag filter for treating exhaust gas from the incinerator, an incinerator ash from the incinerator and an exhaust gas boiler, a gas cooler and a bag filter A direct current resistance ash melting furnace that melts fly ash from the sea, and an exhaust gas from the bag filter and an exhaust gas from the ash melting furnace are combined through a CO gas combustor, and then processed and discharged to the outside. Municipal waste incineration apparatus comprising a wet exhaust gas treatment apparatus, a gas heater, and a NOx decomposition catalyst tower.