JPH11304137A - Treatment of exhaust gas of ash melting furnace and ash melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent attachment of a melt fly ash, which has been carried over to an exhaust gas, to an exhaust gas duct or the like, by providing a secondary combustion chamber for combusting the exhaust gas at the upper portion of a fly ash melting furnace, introducing the exhaust gas to the secondary combustion chamber for subjecting to drastic cooling, and instantly solidifying a liquefied melt fly ash in the exhaust gas for discharge. SOLUTION: One end of an exhaust gas duct 11 is connected to the upper portion of the side wall of a secondary combustion chamber 10, and the other end portion of the exhaust gas duct 11 is connected to a heat exchanger 12, so that an exhaust gas 8 generated in a furnace 3 is led to the heat exchanger 12 through the secondary combustion chamber 10 and the exhaust gas duct 11. Further, a water atomizing nozzle 15 for spraying water 14 by means of air 13 is downwardly provided at a top portion 10a in the vicinity of an exit portion of the secondary combustion chamber 10. The water 14 is atomized from the water atomizing nozzle 15 to drastically cool the exhaust gas 8 in the secondary combustion chamber 10, thereby instantly solidifying a liquefied melt ash carried over to the exhaust gas 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust gas treatment method for an ash melting furnace for melting incinerated ash such as sewage sludge, municipal solid waste and industrial waste, and incinerated ash discharged from a combustion furnace such as a commercial thermal power plant. And an ash melting furnace.

[0002]

2. Description of the Related Art Conventionally, incinerated ash (powder inorganic substance) such as sewage sludge, municipal solid waste and industrial waste has been used, for example, as shown in FIG. It is melted by a simple vertical swirling ash melting furnace 51 and taken out as slag. In such an ash melting furnace 51, a fuel (heavy oil or the like) 52, incineration ash 53, and air 54
Is burned in a tangential direction and burned using a burner or the like.
Becomes The molten slag 55 is supplied to the ash melting furnace 51.
Is dropped by a gravity from a lower slag tap (not shown), and is put into a lower water cooling tank (granulated slag) or a conveyor (air cooled slag) (not shown) to be taken out. Also,
The exhaust gas 56 generated in the furnace of the ash melting furnace 51 is guided from a gas outlet to an upper secondary combustion chamber 57, and the secondary combustion chamber 5
After being burned in 7, it is discharged from the secondary combustion chamber outlet to an exhaust gas duct 58, and guided to a heat exchanger 59 and an exhaust gas treatment facility via the exhaust gas duct 58.

[0003]

However, in the above-mentioned conventional exhaust gas treatment method of the vertical swirling ash melting furnace 51,
The temperature of the exhaust gas 56 guided from the furnace to the heat exchanger 59 is 1
300 to 1500 ° C., and the molten fly ash in the exhaust gas 56 is in a liquid state.
Adheres to the outlet of the secondary combustion chamber 57, the inside of the exhaust gas duct 58 and the fin of the heat exchanger 59 during the discharge, and grows. However, there is a problem that the performance is deteriorated. Therefore, when the molten fly ash 60 adheres to and grows on the exhaust gas duct 58 and the like, it is necessary to stop and clean the apparatus each time, and it has been difficult to improve the productivity.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent molten fly ash carried over in exhaust gas from adhering to an exhaust gas duct or the like and to perform long-term stable operation. It is an object of the present invention to provide an exhaust gas treatment method for an ash melting furnace and an ash melting furnace capable of performing the above.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention relates to a method for treating exhaust gas in an ash melting furnace for melting incinerated ash, wherein the exhaust gas is burned in the upper part of the ash melting furnace. A secondary combustion chamber is provided, and the exhaust gas is introduced into the secondary combustion chamber and quenched, and the liquid molten fly ash in the exhaust gas is instantaneously solidified and discharged. Further, the present invention provides, in an ash melting furnace for melting incineration ash, a secondary combustion chamber for burning exhaust gas at an upper portion of the ash melting furnace,
A quenching means for quenching the exhaust gas is provided in the secondary combustion chamber.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a conceptual view showing a vertical swirling ash melting furnace according to an embodiment of the present invention, FIG. 2 is a sectional view showing an enlarged part A of FIG. 1, and FIG. It is an explanatory view showing a partial outline of equipment to be applied. The ash melting furnace 1 of the present embodiment has a furnace main body 2 formed in a cylindrical shape with a bottom by a refractory material (brick, caster) as shown in FIGS. At the bottom, a slag tap (not shown) for dropping the slag 4 melted in the large-diameter furnace 3 by gravity and discharging the slag 4 is provided.

A fuel (heavy oil or the like) 5 is supplied from a fuel tank (not shown) to the inside 3 of the furnace main body 2, and incineration ash 6 is supplied from an incineration ash hopper (not shown).
Combustion air 7 is supplied from a heat exchanger or the like described later, and these fuel 5, incineration ash 6, and combustion air 7
The slag 4 is melted while being swirled in the furnace 3 by a burner (not shown) to melt the slag 4. Below the ash melting furnace 1, as shown by an arrow, an unillustrated conveyor for collecting the slag 4 dropped by gravity is installed. On the other hand, the inside of the furnace 3
A small-diameter gas outlet 9 is provided for discharging the exhaust gas 8 generated in the above from above. Above the ash melting furnace 1, a secondary combustion chamber 10 that communicates with the gas outlet 9 and burns the exhaust gas 8 is provided.

One end of an exhaust gas duct 11 is connected to the upper part of the side wall of the secondary combustion chamber 10.
The other end is connected to a heat exchanger 12, and the exhaust gas 8 generated in the furnace 3 is discharged from the secondary combustion chamber 10 and the exhaust gas duct 1.
1 to the heat exchanger 12.
On the top 10 a near the outlet in the secondary combustion chamber 10, water 13 (particle size: 100 μm or less) is atomized by air 13.
The water spray nozzle 15 of the quenching means for injecting the water 4 is provided downward, and is configured to quench the exhaust gas 8 in the secondary combustion chamber 10 by spraying water 14 from the water spray nozzle 15. . As shown in FIG. 2, the water spray nozzle 15 is a two-fluid system of air 13 and water 14, and has a tapered air supply pipe 16 and a tapered water supply pipe 17 disposed inside the air supply pipe 16. And a double structure formed by

In addition, the top 10a of the secondary combustion chamber 10
Around the water spray nozzle 15, a ceramic foam 18 through which air 13 can pass is provided,
The air 13 is supplied from the ceramic foam 18 to the secondary combustion chamber 1.
By blowing the gas into the inside 0, the molten fly ash in the exhaust gas 8 does not adhere to the inner wall surface of the secondary combustion chamber 10. In addition, the air supply pipe 16 and the water supply pipe 17
Are connected to a compression pump, a water supply tank, and the like (not shown).

An exhaust gas treatment facility is provided downstream of the heat exchanger 12. That is, the heat exchanger 1
As shown in FIG. 3, the exhaust gas 8 that has passed through 2 is sent to a cyclone (dust collection device) 20 that separates and collects the ash 19 by centrifugal force, and is treated with caustic soda and water, and is then discharged into a flue gas treatment tower 21. And is discharged from the chimney 23 to the atmosphere via the fan 22.

In order to treat the exhaust gas 8 using the swirling ash melting furnace 1, the incineration ash 6 supplied to the furnace 3 is burned and melted while being swirled by the flame of a burner (not shown). I do. The molten slag 4 is dropped by a gravity from a slag tap (not shown) and discharged to a conveyor or the like (not shown) to be collected. On the other hand, the exhaust gas 8 generated in the furnace 3
Is guided from the gas outlet 9 of the furnace body 2 to the secondary combustion chamber 10 where it is burned. The exhaust gas 8 guided to the upper part of the secondary combustion chamber 10 is shown in FIGS.
As shown in (1), the liquid molten fly ash rapidly cooled by the water 14 sprayed from the water spray nozzle 15 and carried over in the exhaust gas 8 is instantaneously solidified. That is, in the exhaust gas 8 at a temperature of the gas outlet 9 of 1500 ° C., the molten fly ash is in a liquid state, but when the exhaust gas 8 is rapidly cooled to 850 ° C., the temperature of the ash melting point becomes 1350 ° C. Also 5
Since the temperature is lowered by 00 ° C., the liquid molten fly ash is instantaneously solidified.

Next, the exhaust gas 8 containing the solidified molten fly ash is introduced from a gas outlet (not shown) of the secondary combustion chamber 10 through an exhaust gas duct 11 to a heat exchanger 12, where the heat exchanger 12 While passing through the inside, heat exchange is performed with the air 13 supplied by the fan 22. The heated air 13 is supplied to the inside of the furnace 3 and the secondary combustion chamber 10. And the heat exchanger 12
As shown in FIG. 3, the exhaust gas 8 passing through the
0 to separate the ash 19, and then sent to a flue gas treatment tower 21 where washing treatment with caustic soda and water is performed. After the washing water is discharged, it is discharged to the atmosphere from a chimney 23 via a fan 22. Is done.

Since a water spray nozzle 15 for rapidly cooling the exhaust gas 8 is provided at the gas outlet in the secondary combustion chamber 10 according to the present embodiment, the liquid molten fly ash in the exhaust gas 8 is instantaneously solidified. This prevents molten fly ash from adhering to the outlet of the secondary combustion chamber 10, the exhaust gas duct 11, and the heat exchanger 12.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes may be made without departing from the spirit of the present invention. What you get. For example, in the embodiment of the present invention, the water spray nozzle 15 is provided as the quenching means. However, if the liquid molten fly ash in the exhaust gas 8 can be quenched and solidified surely, a quenching means having another structure such as a spray method can be used. May be used.

[0016]

As described above, in the method for treating exhaust gas of an ash melting furnace according to the present invention, a secondary combustion chamber for burning exhaust gas is provided at the upper part of the ash melting furnace, and the exhaust gas is guided into the secondary combustion chamber for rapid cooling. Since the molten fly ash in the exhaust gas is solidified and discharged instantaneously, the molten fly ash carried over in the exhaust gas adheres to the inner wall surfaces of the secondary combustion chamber, the exhaust gas duct, the heat exchanger, and the like. , And stable operation can be performed for a long time, thereby improving productivity and reducing costs.

In the ash melting furnace according to the present invention, a secondary combustion chamber for burning exhaust gas is provided above the ash melting furnace, and quench cooling means such as a water spray nozzle for rapidly cooling the exhaust gas is provided in the secondary combustion chamber. With the provision, the same effect as the above invention can be obtained, and the liquid molten fly ash in the exhaust gas can be rapidly and efficiently cooled.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a vertical swirling ash melting furnace according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a portion A in FIG. 1;

FIG. 3 is a conceptual diagram showing a part of equipment to which the swirling ash melting furnace according to the embodiment of the present invention is applied.

FIG. 4 is a conceptual diagram showing a conventional vertical swirling ash melting furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Swirling ash melting furnace 2 Furnace main body 3 Furnace 4 Slag 5 Fuel 6 Incineration ash 7 Combustion air 8 Exhaust gas 10 Secondary combustion chamber 11 Exhaust gas duct 12 Heat exchanger 13 Air 14 Water 15 Water spray nozzle 16 Air supply pipe 17 Water supply Pipe 18 ceramic foam

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroki Honda 1-8-1, Koura, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Heavy Industries, Ltd. Yokohama Research Laboratory (72) Inventor Masao Taguma-ichi Koura, Kanazawa-ku, Yokohama-shi, Kanagawa Mitsubishi Heavy Industries, Ltd. Yokohama Research Laboratory (72) Ishikawa Izukawa, Kanagawa Prefecture, Yokohama City

Claims (3)

[Claims] 1. An exhaust gas treatment method for an ash melting furnace for melting incineration ash, wherein a secondary combustion chamber for burning exhaust gas is provided at an upper portion of the ash melting furnace, and the exhaust gas is introduced into the secondary combustion chamber to be rapidly cooled. An exhaust gas treatment method for an ash melting furnace, comprising instantaneously solidifying and discharging liquid molten fly ash in the exhaust gas. 2. In an ash melting furnace for melting incinerated ash, a secondary combustion chamber for burning exhaust gas is provided above the ash melting furnace, and quenching means for rapidly cooling the exhaust gas is provided in the secondary combustion chamber. An ash melting furnace characterized by the following. 3. The ash melting furnace according to claim 2, wherein said quenching means comprises a water spray nozzle for spraying water.