JPH10122544A - Control method of molten boundary layer in melting furnace of incinerated residue - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method of molten metal level and a control method by determining a time for requiring molten metal-draining and carrying it out in an incinerated residue melting furnace which melts the incinerated residue produced while urban waste or industrial waste or sludge and so forth are incineration-processed. SOLUTION: This melting furnace melts a molten article, such as processed ashes, and forms a molten metal layer and a molten slug layer after another from the bottom of the furnace and overflows the molten slug outside the furnace. In this case, the thickness of the molten metal layer is measured by detecting the interface levels of a molten metal layer M1 and a molten slug layer M2. After having determined whether or not this layer thickness is proper, if it exceeds a pacified layer thickness, at least a part of the molten metal layer is discharged outside the furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting treated ash, such as incinerated ash or fly ash, generated as incineration residue when incinerating municipal solid waste, industrial waste, sludge, etc., in a furnace. The present invention relates to a method for controlling a molten metal level or a molten salt layer thickness in a melting furnace of an incineration residue for collecting molten slag from coal.

[0002]

2. Description of the Related Art In recent years, in order to reduce the volume and detoxification of incinerated ash and fly ash (hereinafter referred to as treated ash) discharged from incinerators such as municipal waste, industrial waste or sludge, the treated ash is melted. Attention has been paid to the solidification treatment method, and it is practically used in practice. The treated ash is melted and solidified to prevent harmful substances such as heavy metals from being eluted, and to reduce the volume by 1/2 to 2
This is because it is reduced to 1/3, and not only the life of the final landfill site can be extended, but also the reuse of the molten slag becomes possible.

Therefore, as a method for melting and solidifying a material to be melted such as treated ash, a plasma melting furnace, an arc melting furnace, an electric resistance furnace or the like is usually used, and the material to be melted is melted by electric energy. The method of solidifying afterwards and the method of using a surface melting furnace, a swirl melting furnace, a coke bed furnace, etc. to melt the material to be melted by the combustion energy of the fuel and then solidify it are often used, and power generation is performed in municipal solid waste incineration equipment. In the case where the facilities are co-located, the former method using electric energy is generally adopted, while when the power generating facilities are not juxtaposed, the latter method using combustion energy is generally adopted.

[0004] Fig. 1 illustrates a conventional example of a plasma melting furnace which is installed in a refuse incineration plant as an example of a melting furnace for incineration residues to which the present invention is applied. 1 is stored in a container 2 and continuously charged into the furnace of a furnace body 4 by a supply device 3 such as a screw conveyor. The furnace body 4 is made of a refractory material that can withstand a high temperature of 1800 ° C. or more, has its outer periphery covered with a heat insulating material, and may be provided with a water-cooling jacket outside.

[0005] A graphite main electrode 5 (negative electrode) which is inserted almost vertically from the furnace top and keeps a certain distance between the furnace body 4 and the material to be melted in the furnace, a furnace bottom 4 installed on the furnace bottom. About 6 volts supplied from the DC power supply 7 between the electrode 6 (plus electrode).
A plasma current of 100 to 1000 kw / ash ton is applied, and the high temperature heat generated by the plasma arc generated there causes
The material 1 to be melted, such as treated ash, is heated to about 1400 ° C. to 1800 ° C. to become slag in a molten state.

In order to make the inside of the furnace a reducing atmosphere, a nitrogen gas is supplied from a nitrogen gas supply device 9 into the furnace. As shown in the figure, the nitrogen gas is supplied into the furnace through a hollow hole passing through the main electrode 5 and the start electrode 8.

[0007] When the treated ash (the material to be melted) is melted, the volatile components and carbon are partially oxidized to become a gas containing carbon monoxide. On the other hand, non-combustible components such as iron and other metals, glass, sand, etc. Is in a molten state. The gas enters the combustion chamber 11 through the upper portion of the outlet 10, where the unburned portion is completely burned by the combustion air supplied by the combustion air fan, and then exhausted from the combustion chamber and cooled. After that, it is led to the chimney via a filter.

Hereinafter, the boundary between the molten metal layer and the molten slag layer will be described as an example. Since the material to be melted 1 contains incinerated ash, silica, alumina, calcia, iron and the like,
When this is melted in the furnace, the molten slag mainly composed of silica, alumina and calcia floats upward,
The molten metal mainly composed of iron sinks downward, and a molten metal layer M1 and a molten slag layer M2 are sequentially formed from the furnace bottom to form two separated layers. Then, the molten slag layer M2 continuously overflows from the outlet 10 and falls into a slag water cooling tank 12 filled with water to become granulated slag.
To the container 14. Since the combustion chamber 11 faces the outlet 10, the molten slag that overflows does not cool and solidify at the outlet 10 to block the flow path.
The slag is suitably dropped into the water cooling tank 12.

[0009]

As described above, the melted material 1 forms a molten metal layer M1 and a molten slag layer M2 in a furnace, and is provided near the molten metal surface of the molten slag layer M2. The molten slag overflows continuously from the outlet 10.

However, since the thickness of the molten metal layer M1 gradually increases while accumulating at the furnace bottom,
1 and the interface between the molten slag layer M2 gradually rises. However, in order to continue normal operation without hindrance, it is necessary that the thickness of the molten slag layer M2 is formed to be at least thicker than about 100 mm. Otherwise, container 2
The slag component and the metal component may flow out unmelted, or may flow out of the outlet 10 without being separated, because the molten material 1 charged from above is not sufficiently melted.

Therefore, when the thickness of the molten metal layer M1 from the furnace bottom exceeds a predetermined thickness, and as a result, the thickness of the molten slag layer M2 decreases, at least a part of the molten metal layer M1 is removed. Hot water must be drained out of the furnace.

[0012] The frequency of the tapping is determined by the amount of the molten material 1 charged into the furnace, the amount of the metal estimated from the incineration ash or fly ash component analysis value as the molten material, the molten metal in the furnace. It is possible to roughly determine by calculation from the storable amount, and in the related art, at present, the timing of hot water drainage is determined based on such a calculated value.

However, since the material 1 to be melted is derived from refuse and waste, the quality and quantity of metal contained in the incinerated ash and fly ash are not always constant, and sometimes there are large fluctuations. It is very difficult to accurately determine the amount of accumulated molten metal in the furnace. As a result, it is necessary to advance the timing of draining the water in consideration of the safety factor or to drain the water frequently, but since the operation must be stopped during the draining operation, the operating efficiency is reduced. Will be.

[0014]

The present invention has been made in view of the above,
The purpose of the present invention is to provide a method for controlling a melting boundary layer in a melting furnace for incineration residues, which accurately determines a time when a drain is required and enables efficient draining. In a melting furnace in which a molten metal layer, a molten slag layer, a molten salt layer, etc. are formed in the furnace by melting a material to be melted, such as treated ash, which has been introduced into the furnace, the molten slag is continuously discharged outside the furnace. When tapping, the level of the interface between the molten metal layer and the molten slag layer and / or the level of the boundary between the molten slag layer and the molten salt layer is detected, and the thickness of each layer from the furnace bottom is measured based on the detected level. A step of determining whether or not the layer thickness of the molten metal layer or the molten salt layer exceeds a predetermined layer thickness; and determining that the layer thickness of the molten metal layer or the molten salt layer exceeds the predetermined layer thickness. A tapping process for tapping at least part of the water outside the furnace There is the point made, et al.

Further, the present invention is configured as a second means. In the measuring step, one probe having the slag level detecting electrode E1 and the metal level detecting electrode E2 is placed in the furnace by the elevating means. When the slag level detection electrode E1 is inserted from the upper atmosphere and reaches the level of the molten salt layer and / or the boundary between the molten salt layer and the molten slag layer, the level of the molten level and / or the interface is changed by the electrode E1. When the metal level detection electrode E2 reaches the interface between the molten slag layer and the molten metal layer after passing through the molten slag layer, the level of the interface is detected by the electrode E2. Until the molten metal level detection electrode E2 passes through the molten slag layer, the electrode E2
The electrode is coated with a coating material so that slag does not adhere to the electrode E2, and then, after the electrode E2 reaches the molten metal layer, the coating material is removed.

Further, the present invention is configured as a third means. In the measuring step, after the metal level detecting electrode E2 covered with the coating material is passed through the molten slag layer, the probe is further lowered. Then, the electrode E2 is immersed in the molten metal layer, and after the coating material is dissolved in the molten metal layer, the probe is raised and the electrode E2 reaches the boundary between the molten metal layer and the molten slag layer. Then, the level of the boundary is detected.

Furthermore, the present invention is configured as a fourth means in that, in the measuring step, the coating material is formed of a material which melts at a high temperature and generates gas during the melting. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 2, in order to carry out the molten metal level control method according to the present invention, the furnace body 4 is provided with a probe insertion hole 15 on the top wall and a tap hole on the side wall near the furnace bottom. 16 are provided. Probe insertion hole 1
It is desirable that 5 has a lid 15a that can be freely opened and closed.

As shown in FIG.
Is usually plugged with a mud material 17 or the like so that the melt in the furnace is not discharged out of the furnace. When the molten metal M1 in the furnace is supplied to the outside of the furnace, as shown in FIG.
The mud material 17 filled therein is excavated, and the molten metal M1 in the furnace can be discharged outside the furnace. When the tapping of the melt is completed, the tap hole 16 is filled with the mud material 17 again by operating the hydraulic or pneumatic mud gun 19 as shown in FIG. Stop tapping of the melt. When the drilling machine and the mud gun are operated by a hydraulic system, the hydraulic pump 2
In the case of the pneumatic type, the operation is performed by starting and stopping the compressor 20 and opening and closing the electromagnetic valve. The facility that implements the molten metal level control method according to the present invention is a pneumatic drilling machine 1 using a compressor 20.
8 and a hydraulic mud gun 19 using a hydraulic pump 21
I use.

The method of tapping the molten metal in the furnace to the outside of the furnace as described in the preceding paragraph is a method using equipment exemplified as one embodiment of the present invention, and a method utilizing Joule heat or tilting the furnace body. There is a way.

A tapping method (not shown) utilizing the Joule heat is such that when molten metal in a furnace is discharged from the furnace, electricity is supplied between the tap hole electrode and the main electrode, and the Joule heat is used. Then, the solidified metal in the tap hole is melted, the tap hole is opened, and the molten metal in the furnace is discharged outside the furnace. When the tapping of the molten metal is completed, the electric circuit between the tap hole electrode and the main electrode is opened, the electric circuit between the furnace bottom electrode and the main electrode is closed, and the operation shifts to a normal melting operation. Such a method is described in Japanese Patent Application No. 8-95108 (applicant: Takuma Co., Ltd., name of invention: electric melting furnace and method of extracting molten metal in electric melting furnace).

In the tapping method (not shown) by tilting the furnace body, the molten metal in the furnace, together with the molten slag in the upper layer, overflows from the slag outlet and flows out of the furnace. When tilting the furnace body, it is performed by operating a hydraulic or electric motor. In the case of the hydraulic type, the hydraulic cylinder is operated by starting / stopping a hydraulic pump and opening / closing of an electromagnetic valve to cause the furnace body to tilt. When an electric motor is used, a ball screw or the like is rotated by starting and stopping the electric motor to tilt the furnace body. When the tapping is finished, it is only necessary to return the furnace body to its original tilt.

The tapping process according to the present invention can be performed by any one of the above-described conventional methods using a hole drill and a mud gun, a method of tilting a furnace body, and a method using Joule heat. You may choose.

The other components of the furnace are the same as those described above with reference to FIG. 1, and the same components are denoted by the same reference numerals as in FIG.

In the operation state shown in FIG. 2, as described above, the material to be melted such as the processing ash is continuously fed into the furnace of the furnace body 4 from the supply device, and the main switch 19 is turned on. The object to be melted is melted by the high-temperature heat (radiant heat) of the plasma arc from the main electrode 5. The melt of the material to be melted causes the molten slag to float upward while the molten metal sinks downward, forming a molten metal layer M1 and a molten slag layer M2 sequentially from the furnace bottom to form two separated layers. . Then, the molten slag layer M2 is continuously overflowed from the outlet 10. In this operation state, it goes without saying that the tap hole 16 is in the closed state.

As the operation proceeds, the thickness of the molten metal layer M1 gradually increases, and the molten metal layer M1 and the molten slag layer M1
2 gradually rises at the interface L. As described above, in order to continue normal operation without any trouble, the thickness of the molten slag layer M2 must be about 100 mm or more, and it is necessary to measure the interface L as needed during operation.

Then, based on the time interval at which the interface L is considered to rise, the level of the interface L is measured by the level probe 20, as shown in FIGS.

As shown in FIG. 7, the level probe 20 is a probe body 2 made of a long paper tube having excellent heat resistance.
A sensor unit 22 is provided at one end.

The sensor unit 22 has a casing 24 with a dish-shaped flange 23 made of ceramics or the like, and has, at its tip, a pair of slag level detecting electrodes E1, E1 for sensing a change in resistance of a contacted object. Further, a pair of metal level detecting electrodes E2, E2 for sensing a change in resistance of the contacted object are projected. These electrodes are refractory cement 25
The lead wire of each electrode is led to the connector 26 provided at the tail end of the casing 24 by being implanted in the dish-shaped flange 23 by being embedded in the casing.

The metal level detecting electrodes E2 and E2 are covered with a coating material 27. The coating material 27 is melted in a short time at a high temperature, and a material that generates gas during the melting. Is formed. The material having such properties can be selected from, for example, one or more of resin, rubber, a thin paper tube, paper or cloth tape, and any other material having similar properties can be used. May be. Further, it is preferable that the coating form covers the entire surface of the electrode E2, but it may be a partial coating including the tip of the electrode E2. However, in the case of partial coating, at least the electrode E2
It is necessary to cover an area of 3 mm or more from the distal end to the proximal end.

The coating material 27 depends on the lowering speed of the probe at the time of level measurement. When the lowering speed is about 6 m / min, the passing time of the molten slag layer is usually less than 1 second. It is preferable to dissolve in about 1 to 3 seconds at a high temperature of C or higher. This erosion time depends on the coating material 2
7, it is also possible to determine by the thickness, for example, in the case of resin, rubber, thin paper tube, paper or cloth tape as described above, the thickness is 0.2 mm
The object can be achieved by setting the distance within a range of about 3.0 mm.

In the present invention, the term "disappearance" of the coating material does not necessarily mean that the coating material is lost when melted, but includes various modes of disappearance at high temperatures such as burning or burning. This is the purpose.

The above-mentioned probe body 21 is inserted into the furnace via a probe insertion hole 15 by a lifting device (not shown) so as to be movable up and down. Ascends and is pulled from the melt. During that time, every time the electrode reacts due to the resistance change, the elevating distance is measured by the distance meter.

A plug is inserted into the connector 26, and the resistance change caused by the reaction of the electrode is detected by external voltmeters V1 and V2. At this time, the electrodes are connected as shown in FIG.
It is preferable to configure a wire-type electric circuit. FIG. 8B
Is a comparative example for the probe of the present invention, and shows a two-wire circuit.

As shown in FIG. 8A, a four-wire circuit employed as an embodiment of the probe 20 according to the present invention includes a pair of slag level detecting electrodes E1 and E1 and a metal level detecting electrode E2. , E2 supplies a constant current to a pair of electrodes in the set.
And two lead wires for connecting a voltmeter V that responds to a change in the resistance value sensed by the pair of electrodes in the set. A total of four lead wires (in the figure, RL1, RL2, RL3, and RL4 (the total resistance of the two sets of electrodes is eight).

Then, by lowering the probe,
Slag bath level detection electrodes E1, E1 is in contact with the melt surface of the molten slag, upon sensing the resistance R ₁ of the slag, voltmeter V1 is, V
1 = R ₁ (Ω) × constant current (A) Similarly, the metal melt surface detection electrode E2, E2 is in contact with the melt surface of the molten metal, upon sensing the resistance R ₂ of the metal, the voltmeter V2, V
2 = R ₂ (Ω) × constant current (A) At this time, since the internal resistance of the voltmeters V1 and V2 is large, the current of the circuit connecting the voltmeter and the electrode becomes close to 0, and the line resistance R
The resistances of L2 and RL3 are almost negligible.

On the other hand, in the case of the two-wire circuit in the comparative example shown in FIG.
Each circuit configured for one set of E1 and one set of the metal level detecting electrodes E2 and E2 uses two lead wires for supplying a constant current to a pair of electrodes in the set. Thereby, the voltmeter V that responds to the change in the resistance value sensed by the pair of electrodes in the set is connected. Therefore, a total of two lead wires (in the figure,
The resistance of each lead wire is indicated by RL1 and RL2) (however, the total of two sets of electrodes is four).

[0039] Therefore, in the two-wire circuit as a comparative example, when the slag bath level detection electrodes E1, E1 senses the resistance R ₁ of the slag, voltmeter V1 _{is, V = (R 1 (Ω} ) +
RL1 (Ω) + RL2 (Ω)) × constant current (A). Similarly, the metal melt surface detection electrode E2, E2 senses the resistance R ₂ of the molten metal, the voltmeter V2, V2 = (R
₂ (Ω) + RL1 (Ω) + RL2 (Ω)) × constant current (A).

For this reason, in the comparative example in which the two-wire circuit is used,
Due to the influence of the line resistance RL1, RL2 directly to the resistor R _1, a sharp reaction voltmeter in response to changes in R ₂ is less likely to expect of the measurement object, also the reaction of the voltmeter changes resistance It is hard to appear as a remarkable difference corresponding to the difference of Moreover, the line resistances RL1 and RL2 usually change their resistance values due to temperature changes. Therefore, the four-wire circuit as in the above embodiment is superior to the two-wire circuit as in the comparative example.

FIG. 8 shows a measurement process performed by using the probe 20. As shown in FIG. 9A, when the probe is lowered by the lifting device, the tip of the probe is placed in the furnace. From the upper atmosphere through the molten salt layer M3 to enter the molten slag layer M2, descend and pass through the molten slag layer M2, enter the molten metal layer M1 and immerse, stop there, stop for several seconds (for example, After a stop state of 1 to 2 seconds), it is raised. At this time, the probe tip is returned from the molten metal layer M1 to the molten slag layer M2, and further passes through the molten salt layer M3 to be pulled up to the upper atmosphere.

Therefore, during one cycle of raising and lowering the probe, the boundary between the molten salt layer M3 and the molten slag layer M2 (the molten metal surface level) and the boundary between the molten slag layer M2 and the molten metal layer M1 are detected. (Interface level) is detected.

FIG. 9B shows a slag level detecting electrode E1,
The response of the voltmeter V1 based on the resistance change detected by E1 is shown. That is, the voltmeter V1 indicates a high voltage value while the probe is in the upper atmosphere, but the slag level detection electrode E
1. When E1 passes through the molten salt layer and touches the molten metal surface of the molten slag layer M2, the voltage value sharply decreases. Therefore, this voltage drop is recorded by a distance meter as the molten metal level of the molten slag. By the way, the slag level detection electrodes E1, E1 are:
After being immersed in the molten slag layer M2, the slag is immediately attached to the slag.
The reaction is disturbed. However, since the slag level detection electrodes E1 and E1 play a role by detecting the level of the molten slag layer, the slag adheres to the slag and may not function normally thereafter.

On the other hand, FIG. 9C shows a voltmeter V based on the resistance change detected by the metal level detecting electrodes E2 and E2.
2 shows the reaction. Metal level detection electrodes E2, E2
Is covered with the covering material 27, the voltmeter V2 does not show a voltage drop even if it enters the molten slag layer M2. That is, as long as the coating material 27 covers the metal level detecting electrodes E2 and E2, the voltmeter V2 indicates the same high voltage value as when the electrodes E2 and E2 are in the upper atmosphere.

When the coating material 27 penetrates into the molten slag layer M2 by descending the probe, gas generation generates violent boiling. Therefore, the metal level detection electrodes E2, E
2 passes through the molten slag layer M2 while the electrodes E2, E2
And the slag is insulated by the coating material 27 or gas to prevent the slag from adhering. Then, until the tip of the probe passes through the molten slag layer M2 and is immersed in the molten metal layer M1, and the descent is stopped there, the coating material 7 continues to be melted while the metal melt level detection electrode E2, E2 is coated. When the lowering of the probe is stopped, the metal melt level detection electrodes E2 and E2 are exposed due to the completion of the melting of the coating material 7, and the voltage value sharply decreases as soon as the molten metal layer M1 is touched. That is, the high voltage value shown under the resistance state close to insulation is, due to the low resistance value of the molten metal having good conductivity,
The voltage value drops rapidly.

Then, when the probe is lifted, the metal level detecting electrodes E2 and E2 sense the change in resistance when moving from the molten metal layer M3 to the molten slag layer M2.
The voltmeter V2 sharply increases the low voltage value indicated by the low resistance value of the molten metal to the voltage value indicated by the high resistance value of the slag. Thus, this voltage rise is recorded by a distance meter as the molten metal surface level of the molten metal layer M1 (the interface level between the molten metal layer and the molten slag layer). Note that the molten metal level detection electrodes E2 and E2 are set so that the molten slag layer M
2, the slag is immediately attached, and after the attachment, the reaction of the voltmeter V2 is disturbed while generating noise. However, the level measurement aimed at by the present invention is completed by the above steps, and the molten metal is removed. Since the molten metal level detection electrodes E2 and E2 play a role by detecting the molten metal level (interfacial level) of the molten metal layer, the slag adheres to the molten metal layer, and the electrodes may not function normally thereafter.

The reaction of the slag level detecting electrodes E1, E1 and the metal level detecting electrodes E2, E2 is detected and recorded by a detector 28 (see FIGS. 3 and 4), and is measured by such a measuring operation. The level of the molten slag layer M2,
Using the level of the interface L as information, the layer thickness of the molten slag layer M2 is measured, and at the same time, the layer thickness of the molten metal layer M1 is relatively measured. Therefore, it is determined whether or not the layer thickness of the molten slag layer M2 satisfies the above condition of about 100 mm or more, in other words, whether or not the layer thickness of the molten metal layer M1 has grown to a predetermined layer thickness.

If it is determined that the molten metal layer M1 is in an overgrown state exceeding a predetermined layer thickness, as shown in FIGS. 5 and 6A, the molten material is introduced into the furnace. Is stopped, and the compressor 20 which is a compressed air source of the drilling machine 18 and the hydraulic pump 21 which is a hydraulic source of the mud gun 19 are operated to prepare for the operation of the tapping process. next,
When the power to the melting furnace is stopped, the drilling machine 18 is operated by opening and closing the solenoid valve or the electric valve, and the mud material 17 filled in the tap hole 16 is excavated. Then, the molten metal in the furnace is poured out of the furnace. The timing of stopping the molten metal tapping may be determined from the tapping time, or may be determined based on a change in the weight of the container 22 that receives the molten tapping metal. When stopping the tapping of the molten metal, the mud gun 19 is moved to the preparation position,
The mud material filled in the mud gun 19 is opened and closed by opening and closing the solenoid valve of the mud gun hydraulic piping, so that the hydraulic cylinder is operated.
And when the filling is completed, the mud gun is evacuated. Upon completion of the tapping of the molten metal, the power supply to the melting furnace is started again, the supply of the molten material into the furnace is started, and the operation is returned to the normal operation. In addition, it is preferable that a worker be notified by a buzzer, a lamp, or another alarm when tapping molten metal.

The method for controlling the molten metal level in the furnace as described above is shown in a flowchart in FIG. 10, and the entire process or a part of the process can be automated under computer control. In the above-described embodiment, the case of tapping the molten metal through the tap hole 16 by using the drilling machine and the mud gun has been described. However, of course, the method using Joule heat or the tilting of the furnace body is described. Depending on the method, the molten metal in the furnace may be tapped.

In the above embodiment, both the slag level detection electrode and the interface detection electrode provided on the level probe 20 detect a change in resistance, and are provided between the molten slag layer M2 and the molten metal layer M1. Operates based on the difference in electrical resistance. That is, the molten slag layer M2 has a molten salt layer on the molten metal surface depending on the material to be melted, but the specific resistance of the molten salt, the molten slag, and the molten metal is 250 to 50, respectively.
Since there is a large difference between 0 μΩ · cm, 1 to 10 Ω · cm, and 150 μΩ · cm, the level of the interface L can be measured by using the difference.

Such a resistance is obtained by the following equation: resistance (Ω) = specific resistance (Ω · cm) × distance between electrodes (cm) / cross-sectional area between electrodes (c
m ² ), for example, the distance between a pair of electrodes is 8 m
m, the diameter of each electrode is φ3 mm, and the protrusion amount of each electrode is 12 mm, the resistance (Ω) of the molten slag is 2.2.
22 to 22.222Ω and the molten metal has a remarkable difference such as 333 μΩ. As a result, the above-described level detection can be reliably performed.

However, in the present invention, the sensor for detecting the level of the slag surface and the level of the interface L may be an electromagnetic coil type utilizing a difference in magnetic permeability, in addition to the resistance type sensor as in the embodiment. good. Further, a composite sensor of an electrode type for detecting a change in resistance and an electromagnetic coil type for detecting a change in inductance may be used. In short, any sensor capable of electrically detecting the level of the slag surface and the level of the interface L may be used.

Incidentally, in the above-described embodiment described with reference to the drawings, a method for controlling the molten slag layer to an appropriate layer thickness by tapping the molten metal has been described. When the layer thickness is measured and the molten salt layer exceeds a predetermined layer thickness, it can be carried out to allow the molten salt to flow out of the furnace. In this case, probe 2
The slag level detection electrode E1 of 0 causes the detector 28 to react by a change in electric resistance value when it comes into contact with the molten level of the molten salt layer M3, and then passes through the molten salt layer M3 to cause the molten slag layer M3 to pass through.
When the detector 2 comes into contact with the molten metal surface, the electrical resistance changes and the detector 2
8 is reacted, so that the thickness of the molten salt layer M3 can be measured based on the detection of these two points. And
When it is determined that the molten salt layer M3 exceeds a predetermined layer thickness, the molten salt may be discharged outside the furnace through a tap hole provided in the furnace wall facing the molten salt layer. In the same manner as in the above-described embodiment in which the molten metal is allowed to flow out of the molten metal, the tap hole is always filled with a mud material, and when the molten salt is discharged, the mud material in the tap hole is opened. It may be configured to excavate with a machine and to discharge molten salt.

[0054]

According to the present invention, the material to be melted, such as treated ash, is melted, and a molten metal layer and a molten slag layer are sequentially formed from the furnace bottom. In the incineration residue melting furnace in which the molten slag overflows out of the furnace, by measuring the level of the interface L between the molten metal layer M1 and the molten slag layer M2, the thickness of the molten metal layer M1 is reduced to a predetermined layer thickness. It is determined whether or not the thickness exceeds a predetermined layer thickness, and when it is determined that the thickness exceeds the predetermined layer thickness, the supply of the molten material into the furnace is stopped, and at least a part of the molten metal layer is discharged outside the furnace. Therefore, there is no inefficiency that the operation is frequently stopped and the hot water is removed as in the prior art, and the operation is stopped only when it is confirmed by measurement that the predetermined thickness of the molten metal layer M1 is exceeded. Can be drained, so in other words, Since fusion metal layer M1 may be continued as it operate if a proper level, very efficient, yet, it is possible to perform always proper sampling of the molten slag under the molten metal level.

According to the present invention, two types of electrodes, a slag level detection electrode E1 and a metal level detection electrode E2, are provided on one probe, and when the probe is lowered and immersed in the molten material, the former is used. , The roles of the molten metal layer M2 and the molten metal layer M3 (interface L between the molten metal layer and the molten slag layer) are detected. As a result, accurate measurement of each level becomes possible. And above all, according to the present invention, while the molten metal surface detection electrode E2 is passing through the molten slag layer M2, it is covered with the coating material 27 so that the slag does not adhere to the surface of the electrode E2. After passing through the layer M2, the coating material 27 is removed and the electrode E2 is removed.
The advantage is that the molten metal level of the molten slag layer M2 and the molten metal level of the molten metal layer M1 can be accurately measured by one test in which one probe is moved up and down. To play.

In particular, according to the present invention, the probe 20 is lowered from when the slag level detecting electrode E1 touches the molten slag layer M2 and detects the level of the molten slag, and the metal level detecting electrode E2 is turned on. Since the coating material 27 boils violently while generating gas until it passes through the layer M2 and reaches the molten metal layer M1, it insulates between the electrode E2 and the slag while bouncing off the slag. The electrode E
2 can be suitably protected from slag adhesion. Then, in a state of being immersed in the molten metal layer M1, the coating material 27 completes the erosion and exposes the surface of the metal melt surface detection electrode E2. Then, when the probe 20 is pulled up, the electrode E2 becomes resistant. By sensing a change in resistance when the molten metal transitions from a small molten metal to a slag having a relatively large resistance value, correct detection of the molten metal level (the interface L between the molten metal layer and the molten slag layer) of the molten metal layer M1 is performed. It is possible and guarantees highly accurate measurement and error-free judgment.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a melting furnace for incineration residues targeted by the present invention.

FIG. 2 is a sectional view showing an operation state according to the embodiment of the present invention.

FIG. 3 shows a measurement process in one embodiment of the present invention.
FIG. 4 is a cross-sectional view illustrating a process of detecting a molten metal level of a molten slag layer.

FIG. 4 shows a measurement process in one embodiment of the present invention.
It is sectional drawing which shows the interface level detection process of a molten metal layer and a molten slag layer.

FIG. 5 is a cross-sectional view showing a tapping process in one embodiment of the present invention.

FIG. 6 shows an example of a tap hole opening / closing method,
(A) is an explanatory view showing a method of opening a tap hole by excavating a mud material, and (B) is an explanatory view showing a method of closing a tap hole by filling a mud material.

7A and 7B show one embodiment of a probe used in the present invention, in which FIG. 7A is a partially cutaway side view showing the vicinity of the tip of the probe main body, and FIG. 7B is a front view showing the tip of the probe. is there.

FIG. 8 is a circuit diagram of an electrode in the probe,
(A) is a circuit diagram showing a four-wire circuit adopted as an embodiment of the present invention, and (B) is a circuit diagram showing a two-wire circuit to be compared as a comparative example.

9A and 9B show a measurement process in one embodiment of the present invention, and FIG. 9A is an explanatory diagram showing an elevating and lowering cycle of a probe;
(B) is a waveform diagram showing a voltage change based on the slag level detection electrode, and (C) is a waveform diagram showing a voltage change based on the molten metal level detection electrode.

FIG. 10 is a flowchart illustrating a procedure when the embodiment of the present invention is performed by computer control or the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 To-be-molten material 3 Supply apparatus 4 Furnace body 5 Main electrode 6 Furnace bottom electrode 7 DC power supply 10 Outflow port 15 Probe insertion hole 16 Tap hole 17 Mud material 18 Punching machine 19 Mud gun 20 Level probe 21 Probe main body 27 Coating material E1 Slag level detecting electrode E2 Molten level detecting electrode M1 Molten metal layer M2 Molten slag layer L Interface between molten metal layer and molten slag layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F27D 19/00 F27D 19/00 Z 21/00 21/00 N (72) Inventor Hiroshi Katayama 1-chome Nishihoncho, Nishi-ku, Osaka-shi, Osaka 7-10 Kawaso Electric Industry Co., Ltd. (72) Inventor Toru Kawabata 7-10 Nishihonmachi, Nishi-ku, Osaka-shi, Osaka, Japan 7-10 Kawaso Electric Industry Co., Ltd.

Claims (4)

[Claims] 1. A melting furnace in which a molten metal layer, a molten slag layer, a molten salt layer, and the like are formed in a furnace by melting a material to be melted, such as treated ash, which has been introduced into the furnace. When the tapping is continuously performed, the level of the interface between the molten metal layer and the molten slag layer and / or the level of the boundary between the molten slag layer and the molten salt layer is detected, and the thickness of each layer from the furnace bottom is determined based on the detected level. And a determination step of determining whether the layer thickness of the molten metal layer or the molten salt layer exceeds a predetermined layer thickness, and when determining that the layer thickness exceeds the predetermined layer thickness, the molten metal layer Or a tapping step of tapping at least a part of the molten salt layer out of the furnace. 2. A probe provided with a slag level detection electrode E1 and a metal level detection electrode E2 is inserted into a furnace by means of raising and lowering means, and the slag level detection electrode E1 is moved from the upper atmosphere to the molten salt layer. When the boundary between the molten metal surface and / or the molten salt layer and the molten slag layer is reached, the molten metal surface and / or the interface is detected by the electrode E1, and after the metal molten metal surface detection electrode E2 passes through the molten slag layer. When reaching the interface between the molten slag layer and the molten metal layer, the level of the interface is detected by the electrode E2, and the electrode E2 is connected to the electrode E2 until the metal level detection electrode E2 passes through the molten slag layer. The incineration residue melting furnace according to claim 1, wherein the electrode is coated with a coating material so that slag does not adhere, and then the coating material is removed after the electrode E2 reaches the molten metal layer. Melting in Control method of the field layer. 3. After passing the molten metal surface detection electrode E2 coated with the coating material through the molten slag layer, the probe is further lowered to immerse the electrode E2 in the molten metal layer.
After eroding the coating material in the molten metal layer, the probe is lifted to detect the level of the boundary when the electrode E2 reaches the boundary between the molten metal layer and the molten slag layer. A method for controlling a melting boundary layer in a furnace for melting incineration residues according to claim 2. 4. The melting boundary of an incineration residue melting furnace according to claim 2, wherein the coating material is formed of a material which is melted at a high temperature and generates gas during the melting. Layer control method.