JPH0570519B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for rapidly stopping slag of melt in a waste melting furnace. More specifically, the present invention relates to a method for immediately stopping the flow of molten material from a waste melting furnace when an emergency situation such as a power outage occurs while the waste melting furnace is in operation.

[Prior Art] Various wastes such as municipal garbage incineration ash, sewage sludge incineration ash, and leather processing sludge incineration ash have conventionally been treated by landfilling or the like. However, due to the difficulty of securing land for landfill, and the risk that the hazardous heavy metals contained in it may leach into the ground and contaminate the area around the landfill site, causing secondary pollution, recently, the above-mentioned disposal A method of melting materials in a melting furnace to render them harmless and reduce their volume has been proposed, and attempts have been made to solve the above problems. An arc heating furnace is known as one type of melting processing furnace, and a typical example thereof is a submerged arc heating furnace.

This melting furnace consists of a furnace body with a fireproof structure equipped with a molten slag outlet, and a furnace lid equipped with a waste inlet, multiple main electrodes, a gas exhaust duct, etc.
This is equipped with a water crushing tank that receives the molten material discharged from the slag outlet, cools it, solidifies it, and crushes it. Further, in front of the slag outlet, an auxiliary electrode for heating is arranged so that the molten material will not be cooled and solidified there during discharge, thereby preventing the slag discharge from being obstructed.

Then, the lower end or about half of the entire length of the electrode is buried in the waste thrown into the furnace main body from the waste inlet, and by energizing the electrode,
Arc heat is generated, and the input waste is sequentially melted and discharged from the furnace through the slag outlet, cooled in a water crushing tank, and crushed and solidified into fine sand.

[Problems to be solved by the invention] The melting process using a submerged arc heating furnace is
As mentioned above, the lower end of the electrode or about half of its total length is buried in the waste to be processed, but as the waste is heated and melted, the level of the melted surface of the molten material in the furnace rises, causing the slag to come out. The slag overflows out of the furnace through the U-shaped notch groove of the weir brick provided at the mouth and is continuously discharged.

However, in the event of a total power outage due to an emergency such as a lightning strike or disconnection accident during the melting process, not only will power be transmitted to the main electrode and auxiliary electrode, but the granulated water supply pump attached to the granulated water tank will not be able to operate. Stop. In this case, the melt continues to overflow and be discharged out of the furnace until it reaches below the level of the U-shaped notch of the weir brick. That is, the slag is not immediately stopped.
Therefore, if only the water stored in the granulation tank is used, the cooling effect will be insufficient, and in some cases, there is a risk of causing a steam explosion.Also, if a large amount of water solidifies at the bottom of the granulation tank, it will be difficult to remove it. Something bad could happen. In order to avoid this, a large-capacity water granulation tank may be installed, but this is not necessarily advantageous in terms of equipment cost and installation space.

An object of the present invention is to provide a safe operating method that can immediately deal with such a situation.

[Means for Solving the Problems] The present invention solidifies the molten material at the furnace slag outlet, dams the melt from overflowing, and immediately stops the slag extraction when the above-mentioned emergency situation occurs. It is something. However, the gist of it is that
Melting in a waste melting furnace characterized by spraying a coolant having a specific gravity equal to or higher than that of the molten material in front of the slag outlet when rapidly stopping the slag output in the waste melting furnace. It consists in a method for rapidly stopping the slag discharge.

The present invention will be explained below based on the drawings.

FIG. 1 is a schematic side view of a submerged arc furnace, which is one of the melting furnaces to which the method of the present invention is applied. The furnace body is constructed of materials. The upper surface of the furnace body 1 is covered with a furnace lid 2. A plurality of main electrodes 3 pass through the furnace lid 2, and an incineration ash inlet 4 and an exhaust gas duct 5 are provided. A slag outlet 6 is provided below the furnace body 1, as shown in the enlarged schematic side view in FIG. 2 and in FIG. , a refractory weir brick 7 having a U-shaped cutout groove 8 is provided, through which the molten material formed in the furnace body 1 overflows and slags out of the furnace. The molten material passage from the furnace body 1 to the slag outlet 6 is constructed in the form of a gutter, and an auxiliary heating electrode 9 is provided to prevent the molten material from solidifying here during normal slag tapping. A molten initiator inlet 12 is provided for charging the initiator 10 from the molten initiator storage hopper 11 . Furthermore, a coolant inlet 15 is also provided for dispersing the coolant 14 from the coolant storage hopper 32 in an emergency.
5 and the coolant storage hopper 14, an opening/closing pot 13a for adjusting the amount of coolant 14 input is provided. The above coolant input port 15,
Both the melting accelerator inlet 12 and the auxiliary heating electrode 9 are arranged in the slag outlet cover 16. Immediately below the slag outlet 6, there is a space for receiving the molten material to be slag discharged,
A water pulverization tank 18 filled with water 17 is arranged to rapidly cool the water and solidify it into fine particles.

The entire bottom surface of the furnace body 1 is lined with a castable 1A made of a refractory material, and the castable 1A is constructed in the form of a gutter near the slag outlet 6 to facilitate the discharge of the melt. .

This furnace is an improved version of the furnace generally used for refining pig iron, ferroalloy, copper, zinc, tin, etc., and for manufacturing chemical products such as carbide, phosphorus, and soluble phosphorous fertilizer. This is a melting furnace that melts waste while generating an arc between the object to be melted or the molten material inserted into the furnace.

The method of operating the furnace is to first sequentially charge incinerated ash a as the incinerated material from the incinerated ash input port 4 so as to have a uniform thickness, and then melt the incinerated ash a. Through this treatment, two layers are formed from the incineration ash a: a molten metal layer b mainly composed of metal components and a molten slag layer c mainly composed of inorganic components, and the molten metal layer b,
On top of that, a molten slag layer c is layered, and further on top of that, a partially molten incineration ash a is layered.

The molten material (molten slag c) formed in the furnace body 1
The molten metal layer B) maintains a high temperature of 1,350 to 1,550°C, but when its volume increases due to continuous charging of incinerated ash a, it flows from the U-shaped notch groove 8 of the weir brick 7 of the discharge port 6. It overflows and falls into the granulation tank 18 as falling material d.

The present invention is an emergency treatment method when an emergency situation such as a power outage occurs during the melting process and it is necessary to immediately stop the melt from being discharged from the furnace and falling into the granulation tank. This method is characterized in that a coolant is sprinkled in front of the outlet in the furnace body, and the molten material is solidified at the slag outlet.

Spreading of the coolant occurs on the melt flowing through the channel constructed in the shape of a gutter before reaching the slag outlet 6. In this case, from a control device (not shown) that receives an electric signal of a power outage, a switch 13a provided at the bottom of the coolant storage hopper 13
It is preferable to provide a control mechanism that issues an opening command.

Examples of the type of coolant include those having good thermal conductivity and large heat capacity, such as steel ball shot blast, magnetic separation shot blast, scrap shot blast, and soft blast.

Further, it is necessary to select a coolant having a specific gravity equal to or greater than that of the molten material formed within the furnace body. That is, the specific gravity of the melt is
Usually, molten slag mainly composed of inorganic components is about 2.6
When molten metal is mixed therein, the specific gravity is about 3, so it is preferable to use a material with a bulk specific gravity of 4 or more and a true specific gravity of 7.8 or more. By selecting a coolant with such a specific gravity, when spraying the molten material flowing from the furnace main body to the slag outlet 6 in an emergency, the coolant will not float on the surface of the coolant and will be dispersed further into the molten material. It penetrates well and promotes solidification of the molten material near the slag outlet 6.

Furthermore, it is preferred that the coolant used in the method of the invention has a particle size in the range 0.5 to 5 mm. In general, among wastes, for example, municipal garbage incineration ash has a basicity (same as CaO/SiO ₂ and below) of 0.6 or less, and sewage sludge incineration ash and leather sludge incineration lung have a basicity of 1.0 or more. Therefore, the viscosity of the melted material also differs. For example, the viscosity of the molten material from municipal waste incineration ash is 50 to 80 Pa・S, whereas the viscosity of sewage sludge incineration ash and leather sludge incineration ash is 5 to 20 Pa・S.
This is 1/4 to 1/10 smaller than the former. Therefore, in the method of the present invention, it is preferable that the particle size of the coolant used is selected within the above range so that it can resist the viscosity of the melt and penetrate well into it, which varies depending on the type of waste. . That is, for example, for molten material with a low basicity value and high viscosity, such as municipal waste incineration ash, a large amount of coolant with a relatively small particle size, for example, 0.5 to 3 mm, is used, and sewage sludge is For melts with high basicity values and low viscosity, such as incineration ash and leather sludge incineration ash, a small amount of coolant having a relatively large particle size, for example, 1 to 5 mm, is used. In this way, by applying coolants with different particle sizes depending on the viscosity of the molten material, the molten material formed in the furnace body can resist viscosity in the trough-like passage leading to the slag outlet 6. It blends well with the flow of the molten material, cools and solidifies the molten material, and exhibits the effect of rapidly stopping slag extraction.

Further, the amount of coolant sprayed is usually 30 kg or more, although it varies depending on the capacity of the melting furnace, the discharge speed of the melt, the discharge amount, the discharge temperature, etc.

[Operation] In an emergency, by spraying a coolant in front of the slag outlet, the molten material overflowing to the outside of the furnace will solidify there, and the flow of slag from the dammed head will be immediately stopped. Therefore, the discharge of molten material to the fracking tank is immediately interrupted, so even if water supply is stopped due to the granulated water supply pump stopping operation, there may be a steam explosion due to this, or the inside of the fracking tank may be damaged due to excessive discharge of molten material. This prevents unforeseen situations such as solidification. Furthermore, since the solidified area near the slag outlet is small, it is easy to restart the remelting operation using the auxiliary heating electrode.

[Example] Municipal waste incineration ash (moisture content 10%) was melted at a rate of approximately 1 ton/hr in a waste melting furnace (submerged arc furnace) as shown in Figure 1 with a hearth area of ^3.3M3 . Upon treatment, molten material (molten slag and molten metal) was produced at a rate of approximately 800 kg/hr. The molten metal in this melt is 5 to 10% of the total, mostly iron. Further, the specific gravity of the molten slag mainly composed of inorganic components was about 2.6, and the specific gravity of the entire molten material including the molten metal was about 3.

Assuming an emergency due to a power outage, we stopped the input of municipal waste incineration ash and the power supply to the electrodes, and within 6 to 10 minutes after the shutdown, 80 to 150 kg of melted from the slag outlet. Materials flowed out and the slag stopped.

Next, we restarted the "power supply to the electrodes" and the "injection of municipal waste incineration ash" to return to the normal melting process operation, and then "stopped" the process again, and immediately used the coolant as a particle size of 1 to 1. 2mm, bulk specific gravity 4, true specific gravity
Approximately 30 kg of 7.8 steel ball shot blast was sprayed onto the gutter near the slag outlet. As a result, the flow of molten material from the slag outlet stopped after about 30 seconds.

As a comparative example, approximately 50 kg of granulated slag with a bulk specific gravity of 1.1 to 1.5 and a true specific gravity of 2.7 was sprayed instead of the steel ball shot blasting in the previous example, but although it mixed into the flow of the molten material, It was not possible to immediately stop the flow of the melt from the slag opening.

[Effects] As described above, the present invention sprays a coolant having physical properties in a specific range in front of the slag outlet of a melting processing furnace in the event of an emergency to suddenly stop the flow of molten material. This system avoids steam explosions and large solidification of molten material in the crushing tank, thereby improving safe operation and efficiency, and can greatly contribute to the waste treatment field.

[Brief explanation of the drawing]

The drawing shows one of the melting furnaces to which the method of the present invention is applied.
To illustrate an example, FIG. 1 is a schematic side view, FIG. 2 is a partially enlarged view of the vicinity of the slag outlet in FIG. 1, and FIG. 3 is a view taken in the direction of the arrows in FIG. 2. 1... Furnace body, 2... Furnace lid, 3... Main electrode, 4
...Incineration ash input port, 5...Exhaust gas duct, 6...
Slag outlet, 7... Fireproof weir brick, 9... Auxiliary heating electrode, 13... Coolant storage hopper, 14... Coolant, 15... Coolant inlet, 18... Water fracking tank.

Claims (1)

[Claims] 1. In rapidly stopping the molten material slag in a waste melting processing furnace, a coolant having a specific gravity equal to or higher than that of the molten material is sprayed in front of the slag outlet. A method for stopping slag production in a waste melting processing furnace. 2. The method for stopping slag production in a waste melting processing furnace according to claim 1, wherein the waste is any one of municipal garbage incineration ash, sewage sludge incineration ash, or leather processing sludge incineration ash. 3. The method for stopping slag extraction in a waste melting processing furnace according to claim 1, wherein the coolant is shot blasting of steel balls having a diameter of 0.5 to 5 mm. 4 The waste is municipal garbage incineration ash, and the coolant is
A method for stopping slag in a melting processing furnace according to claim 1, which is shot blasting of steel balls having a diameter of 0.5 to 3 mm. 5. The method for stopping slag in a melting processing furnace according to claim 1, wherein the waste is sewage sludge incineration ash or leather processing sludge incineration ash, and the coolant is steel ball shot blasting with a diameter of 1 to 5 mm.