JPH0989226A - Electric ash melting furnace and waste gas combustion method by the melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To completely burn combustible gas contained in waste gas and reduce the volume of a re-combustion chamber. SOLUTION: A slug outlet chamber 11 is provided corresponding to a slug outlet 9 of slug S at a melting chamber 2 of a furnace main body 3 and a waste gas re-combustion chamber 12 is provided above the slug outlet chamber 11. A combustion burner 14 is arranged on a rear wall 12a of the re-combustion chamber 12 and a secondary air nozzle 15 is installed above the combustion burner 14 to spout secondary air toward the slug outlet chamber 11 to form a circulating stream M circulating across the slug outlet chamber 11 and the re-combustion chamber 12. The circulating stream M stimulates waste gas and the secondary air to mix up together and allows combustion to take place also in the slug outlet chamber 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention heats and melts incinerated ash discharged from a refuse incinerator or the like with electric energy such as plasma, electric arc, and Joule heat to reduce the volume and render it harmless. The present invention relates to an electric ash melting furnace and a method for burning exhaust gas in the electric ash melting furnace.

[0002]

2. Description of the Related Art As this type of ash melting furnace, there is a plasma ash melting furnace having a carbon electrode. In this plasma ash melting furnace, when the furnace is in an oxidizing atmosphere, an inert gas such as argon gas or nitrogen gas is used as a plasma working gas to prevent the electrodes from being consumed, and the furnace is kept in a reducing atmosphere. It heats and melts. Therefore, exhaust gas containing a large amount of combustible gas such as CO and H ₂ is generated from the melting chamber.

Conventionally, in order to treat the combustible gas, as shown in FIG. 3, the exhaust gas discharged from the melting chamber 32 of the furnace body 31 through the outlet 33 is introduced into the exhaust gas passage on the downstream side. The burner 35 for combustion is introduced into the reburning chamber 34 provided.
Was completely burned. In addition, the combustion burner 35
Is disposed on the side wall facing the lower part of the outlet port 33, and heats the molten slag flowing out and falling from the outlet port 33 to prevent solidification due to a temperature decrease, and at the same time, ignites the combustible gas in the exhaust gas, Further, complete combustion is performed by the secondary air supplied from the secondary air nozzle 36 arranged above the combustion burner 35 toward the outlet 33 side.

[0004]

However, in the above-mentioned conventional structure, the combustible gas in the exhaust gas and the secondary air are liable to be incompletely mixed, and may be discharged without being completely combusted in the recombustion chamber 34. However, there is a problem that the unburned gas may cause ignition or explosion on the downstream side of the exhaust gas passage. In addition, the gas containing unburned components is
4 Stagnation in the lower slag extraction chamber 37, and when it reached a certain concentration and temperature, abnormal combustion and explosion occurred due to air leakage, which was a problem in operation. Further, since a large amount of combustible gas generated in the melting chamber 34 is processed only in the reburning chamber 34, a large volume of reburning chamber is required, which is not preferable in terms of space efficiency.

The present invention solves the above problems and can completely combust combustible gas in exhaust gas, and also can reduce the volume of the recombustion chamber, and an exhaust gas combustion method in an electric ash melting furnace and an electric ash melting furnace. The purpose is to provide.

[0006]

In order to achieve the above-mentioned object, the electric ash melting furnace of the present invention forms a slag outlet of molten slag in a melting chamber having a heating means by electric energy in the furnace body, An electric ash melting furnace in which a slag extraction chamber is provided corresponding to this outlet, an exhaust gas re-combustion chamber is provided above this slag extraction chamber, and a combustion burner is arranged on the side wall of this re-combustion chamber. In, above the combustion burner,
A secondary air nozzle for injecting secondary air toward the slag extraction chamber side to form a circulation flow between the slag extraction chamber and the re-combustion chamber is provided. Further, the combustion method of the exhaust gas in the electric ash melting furnace corresponds to the outlet of the molten slag in the melting chamber having a heating means by electric energy,
In the electric ash melting furnace in which the reburn chamber is formed on the exhaust gas path, and the slag extraction chamber is formed continuously under the reburn chamber, the exhaust gas discharged from the outlet to the reburn chamber When combustible gas is ignited by a combustion burner and burned, secondary air is injected from the secondary air nozzle provided in the re-combustion chamber toward the slag extraction chamber, so that the slag extraction chamber and the re-combustion chamber A combustible gas and secondary air are mixed in the exhaust gas by forming a circulation flow in and to combust the combustible gas in the slag extraction chamber and the re-combustion chamber.

According to the above construction, since a large circulation flow is formed by the secondary air between the re-combustion chamber and the slag extraction chamber, the stagnation of the exhaust gas is eliminated and the mixing of the exhaust gas with the secondary air is promoted. Exhaust gas is completely combusted, and flammable gas is not emitted. Further, since the combustible gas is burned in the slag extraction chamber, the volume of the re-combustion chamber can be made smaller than in the conventional case, and the size can be made compact.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Here, an embodiment of a plasma type ash melting furnace according to the present invention will be described with reference to FIGS.

This plasma type ash melting furnace has a furnace body 3 having a melting chamber 2 for storing a molten base metal 1 at the bottom.
And 2 inserted into the melting chamber 2 from the top wall 3a of the furnace body 3.
Plasma torch (anode, cathode) which is the heating means of the book 4,
5, an ash supply hopper 7 and a pusher 8 for supplying incineration ash into the melting chamber 2 through an ash charging port 6 formed in the front wall 3b of the furnace body 3, and a rear wall 3c of the furnace body 3. A squeeze dam 9a provided at the slag outlet 9, a slag extraction chamber 11 provided at a lower portion corresponding to the slag outlet 9, and discharged from the slag outlet 9 above the slag extraction chamber 11. And a re-combustion chamber 12 formed on the exhaust gas passage. Further, below the slag extraction chamber 11, a slag cooling device 13 having a water granulation pit 13a for water-cooling the molten slag S discharged from the slag outlet 9 and a slag discharge conveyor 13b is arranged.

A combustion burner 14 is installed on the rear wall (side wall) 12a of the re-combustion chamber 12 so as to face the lower portion of the outlet port 9, and the molten slag S is heated and solidified by the combustion burner 14. And the exhaust gas containing the combustible gas discharged from the melting chamber 2 can be ignited.
Further, on the side wall 12a near the upper portion of the combustion burner 14,
A pair of left and right secondary air nozzles 15 are provided.

The tip of the secondary air nozzle 15 is opened downward, and the high pressure secondary air sent from a high pressure air supply device (not shown) is located below the slag extraction chamber 11.
The secondary air forms a large gas circulation flow M in the slag extraction chamber 11 and the re-combustion chamber 12 to eliminate the stagnation of the exhaust gas and to contain the combustible gas. It is possible to promote the mixing of the exhaust gas and the secondary air to complete the combustion. Further, an exhaust gas pipe introduced into an exhaust gas treatment facility is connected to a gas exhaust port 12b formed at the top of the reburning chamber 12.

In the above structure, when the incineration ash is charged into the melting chamber 2 through the ash input port 6 by the ash supply hopper 7 and the pusher 8, the inside of the plasma torches 4 and 5 and the gas supply nozzle (not shown). The incineration ash is heated and melted by the plasma arc formed between the plasma torches 4 and 5 and the base metal 1 in an atmosphere of an inert gas, for example, a nitrogen gas, which is supplied from the inside to the melting chamber 2. And
The molten slag S that has risen to a predetermined level is heated from the slag port 9 by the combustion burner 14 and is charged into the water granulation pit 13a through the slag extraction chamber 11 to form water granulated slag.

On the other hand, the exhaust gas generated in the melting chamber 2 is discharged from the outlet 9 to the re-combustion chamber 12, and the combustible gas contained in the exhaust gas is ignited and burned by the combustion burner 14. Furthermore, the slag extraction chamber 11 from the secondary air nozzle 15
Due to the secondary air injected at high speed toward the exhaust gas, a strong circulation flow M is generated in the exhaust gas from the slag extraction chamber 11 to the re-combustion chamber 12, and the mixing of the secondary air and the exhaust gas is effectively promoted. The contained combustible gas is completely burned.

According to the above embodiment, the combustion burner 1
4, a secondary air nozzle 15 for injecting secondary air downward from above the slag extraction chamber 11 is provided, so that a large swirling flow M from the slag extraction chamber 10 to the re-combustion chamber 12 is provided.
Can be formed, the stagnation of the exhaust gas can be eliminated, the mixing of the exhaust gas with the secondary air can be effectively promoted, and the combustible gas in the exhaust gas can be completely burned.

Further, since the swirl flow M is formed from the slag extraction chamber 11 to the re-combustion chamber 12, the combustible gas can be burned in the slag extraction chamber 11 as well, and is burned only in the conventional re-combustion chamber 12. However, the volume of the re-combustion chamber 12 can be reduced as compared with the conventional one, because it can be expanded to the slag extraction chamber 11. Moreover, since the molten slag S can be heated by burning the combustible gas in the slag extraction chamber 11, the fuel for the combustion burner 14 can be saved and the operating cost can be reduced.

[0016]

As described above, according to the first aspect of the present invention, the secondary air forms a large circulation flow between the re-combustion chamber and the slag extraction chamber, so that the exhaust gas does not stagnant. The mixing of the exhaust gas with the secondary air is promoted, the exhaust gas is completely combusted, and the combustible gas is not discharged. Further, since the combustible gas is burned in the slag extraction chamber, the volume of the re-combustion chamber can be made smaller than in the conventional case, and the size can be made compact.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a plasma-type ash melting furnace according to the present invention.

FIG. 2 is a sectional view taken along line AA shown in FIG.

FIG. 3 is a side sectional view showing a conventional plasma-type ash melting furnace.

[Explanation of symbols]

 S molten slag M circulating flow 1 base metal 2 melting chamber 3 furnace body 4,5 plasma torch 9 slag outlet 9a throttle weir 11 slag extraction chamber 12 re-combustion chamber 13 slag cooling device 14 combustion burner 15 secondary air nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kosaka 5-3-8 Nishikujo, Konohana-ku, Osaka City, Osaka Prefecture Hitachi Shipbuilding Co., Ltd. 3-28 Hitachi Shipbuilding Co., Ltd. (72) Inventor Hideo Sato 5-3-28 Nishikujo, Konohana-ku, Osaka-shi, Osaka Prefecture Hitachi Shipbuilding Co., Ltd. (72) Tsuneharu Sakakibara Nishikujo, Osaka-shi, Osaka 5th-328th Hitachi Shipbuilding Co., Ltd.

Claims (2)

[Claims] 1. A slag outlet for molten slag is formed in a melting chamber having a heating means by electric energy in a furnace body, and a slag extraction chamber is provided corresponding to the slag outlet, and the slag extraction chamber is also provided. In the electric ash melting furnace in which an exhaust gas re-combustion chamber is provided in the upper part of the combustion chamber, and a combustion burner is arranged on the side wall of the re-combustion chamber, above the combustion burner, the secondary air flows toward the slag extraction chamber side An electric ash melting furnace characterized in that a secondary air nozzle for injecting air into the slag extraction chamber and the re-combustion chamber to form a circulation flow is provided. 2. A recombustion chamber is formed on the exhaust gas path corresponding to the outlet of the molten slag in the melting chamber having a heating means by electric energy, and the slag is continuously withdrawn under the recombustion chamber. In an electric ash melting furnace with a chamber formed, when the combustible gas in the exhaust gas discharged from the outlet to the reburning chamber is ignited by the combustion burner and burned, the secondary air provided in the reburning chamber. By injecting secondary air from the nozzle toward the slag extraction chamber, a circulating flow is formed in the slag extraction chamber and the re-combustion chamber to mix the combustible gas in the exhaust gas with the secondary air, and to remove the slag. A method for burning exhaust gas in an electric ash melting furnace, which comprises burning a combustible gas in a discharge chamber and a re-combustion chamber.