JP2988313B2 - Method and apparatus for measuring depth of molten metal in incineration ash melting furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a melting furnace which is a melting facility for melting incineration ash of waste such as refuse incineration ash and sewage sludge. The present invention relates to a method and an apparatus for measuring a molten metal surface depth of an incineration ash melting furnace for measuring the depth.

[0002]

2. Description of the Related Art Wastes such as incinerated ash of municipal solid waste and incinerated ash of sewage sludge contain various inorganic and organic substances. If these are buried as they are, serious secondary pollution occurs.
Therefore, in recent years, incineration ash melting furnaces have been used to detoxify such wastes.

[0003] In this melting furnace, most of the waste is converted into a molten slag, which is a vitreous melt, and a metal contained in the incinerated ash is melted by resistance heating by energizing between electrodes inserted into the molten slag. It is made of metal, separated from each other and discharged to the outside. Then, in order to operate the melting furnace efficiently, it is desirable that a predetermined amount of waste is sequentially charged into the melting furnace, a large amount of molten slag is continuously taken out, and a small amount of molten metal is taken out intermittently. The condition in this case is that the slag surface in the furnace is always kept in a predetermined position range so that the height difference between the molten metal surface (slag surface) and the slag outlet is always in a predetermined range. is necessary.

[0004] Since the upper part of the melting furnace is sealed, the position of the slag surface in the furnace cannot be known. And since the ratio of organic matter and inorganic matter contained in the waste is not known, even if a predetermined amount of waste is put into the melting furnace, the position of the slag surface fluctuates. If the mouth is clogged or the position of the slag surface is too high, the molten slag may overflow from the furnace. Also, the metal content in the waste incineration ash varies, so the molten metal surface (metal surface)
Also fluctuated from the assumed position based on the amount of incinerated ash, and it was unclear when to extract the molten metal. Furthermore, when the amount of molten metal was increased and the metal was taken out of the slag port at the same time, the metal was mixed into the molten slag, and the slag became difficult to reuse.

[0005] In order to avoid such a situation, the position of the slag surface in the furnace is known, and the removal of molten slag and molten metal is adjusted accordingly, and the amount of incinerated ash is adjusted to adjust the slag surface. In addition, it is required to keep the metal surface within a certain range.

Conventionally, in an incineration ash melting furnace having a closed upper part, a method and an apparatus for measuring a molten metal surface depth of a melting furnace capable of knowing a position of a slag surface in the furnace have been as follows.

[0007] Measuring method of the depth of the molten metal: The position of the molten metal is detected by sensing the temperature of the molten slag in the furnace with a thermocouple with a protective tube inserted into the furnace from the furnace lid, and the temperature of the molten metal is directly measured. (Hereinafter, referred to as “prior art 1”).

Liquid surface depth measuring device: Japanese Patent Laid-Open No. 6-19420
No. 8, proposed by a wire feeder for feeding a metal wire at a predetermined feed rate from a furnace top to a terminal plate provided on the furnace bottom, and fed by a wire feeder. An encoder for measuring a feed amount of the wire, a power supply device for supplying a voltage to the wire and the terminal plate, a unit for measuring a voltage between the wire and the terminal plate or a current flowing through the wire, and the encoder measures And calculating means for calculating the positions of the slag surface and the metal surface from the furnace top based on the wire feed amount and the voltage change or the current change (hereinafter referred to as “prior art 2”).

According to Prior Art 2, a metal wire is fed by a wire feeder from a furnace top of a melting furnace to a terminal plate provided on the furnace bottom at a predetermined feed amount, and the wire is fed by an encoder. The feeding amount of the wire sent out by the feeding device is measured, a predetermined voltage is applied to the wire and the terminal plate by the power supply device during the wire feeding, and the voltage between the wire and the terminal plate during the wire feeding is measured. The change is measured with a voltmeter or the change in current flowing through the wire with an ammeter, and the arithmetic means measures the feed amount of the wire measured by the encoder based on the voltage change of the voltmeter or the current change of the ammeter. Since the positions of the surface and the metal surface are calculated, the positions of the slag surface and the metal surface from the furnace top of the melting furnace can be known from the calculation values of the calculation means.

[0010]

In the prior art 1 of the conventional methods for measuring the level of molten metal, since the temperature of the molten slag of extremely high temperature is repeatedly measured, the life of the protective tube and the thermocouple is shortened. It is treated as a consumable item and needs to be replaced quite frequently.

In the prior art 2, it is extremely difficult to accurately send out a metal wire in the vertical direction to the furnace bottom, and bending is likely to occur. Further, since the upper part of the melting furnace is closed, the state of the wire in the furnace cannot be confirmed. Therefore, it is considered that the measurement error increases. In addition, the wire for measurement can be used only once, and it is necessary to cut and feed the wire for each measurement. In addition, dangerous work on the furnace such as replacement of the wire drum is required.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such a problem, and a method of forming an incineration ash layer on a molten slag upper surface in a melting furnace having a closed upper portion. In the incineration ash melting furnace, the measurement of the position of the molten slag and the molten metal surface can be performed accurately and without complicated and dangerous work using measuring equipment that can be used for a long time without replacement It is an object of the present invention to provide a method and apparatus for measuring the depth of a molten metal surface.

[0013]

According to the first aspect of the present invention,
A molten slag discharge port is provided on the furnace wall in the middle of the height direction of the incineration ash melting furnace, a discharge port for molten metal is provided on the furnace wall near the bottom of the melting furnace, and incineration ash is charged into the melting furnace. The electrode penetrates through the incineration ash layer, is inserted into the molten slag of the incineration ash, and the incineration ash is separated into the molten slag and the molten metal by electric resistance heating to separate the molten slag layer and the molten metal layer thereunder. During the melting, the tip of the electrode is disposed in the molten slag layer by penetrating the incineration ash layer covering the upper part of the molten slag layer, and the molten slag is melted from the slag port. In a method for measuring the surface level of an electric resistance type incineration ash melting furnace in which metal is separately discharged from the discharge port, the tip of a thermocouple with a protective tube is inserted into the incineration ash layer to form the incineration ash layer. The temperature was measured in the range of 1200 ° C. or less, It is characterized in that the distance is obtained by calculation from the temperature change of the ash layer and a relational expression of the distance from the thermocouple tip to the molten slag surface, and thus the position of the molten slag surface is obtained. is there.

According to a second aspect of the present invention, the position of the molten metal surface of the molten slag obtained by the method of the first aspect and the weight of the melting furnace are measured by a load cell installed at a lower part of the melting furnace, and the load cell is measured. From the measured value, the weight of the molten metal in the melting furnace determined by subtracting the weight of the apparatus provided in the furnace main body and the furnace body measured by the load cell, and the known molten slag and molten metal. The method is characterized in that the position of the molten metal surface is obtained by calculation based on the specific gravity value and the area of the bottom surface in the melting furnace.

The third aspect of the present invention provides the first or second aspect.
In the described invention, a plurality of thermocouples with a protective tube are arranged by changing the heights of the tips thereof, and the temperature of the incinerated ash layer is measured by each thermocouple with a protective tube, whereby the thermocouple with a protective tube is provided. It is characterized in that each of the thermocouples is used for mutual backup and for alarming the upper limit of the molten slag level.

A fourth aspect of the present invention is characterized in that, in the first, second or third aspect of the present invention, the protection tube of the thermocouple with a protection tube is made of a cermet heat-resistant material.

According to a fifth aspect of the present invention, there is provided a slag outlet for molten slag on a furnace wall at an intermediate portion in a height direction of a melting furnace, and an outlet for molten metal on a furnace wall near the bottom of the melting furnace. The electrode penetrates through the incineration ash layer, is inserted into the molten slag of the incineration ash, and the incineration ash is separated into the molten slag and the molten metal by electric resistance heating to separate the molten slag layer and the molten metal layer thereunder. In the electrical resistance type incineration ash melting furnace to be formed, in the molten metal surface depth measuring device, the molten metal slag layer is inserted only into the incineration ash layer covering the upper part of the molten slag layer by controlling the height of the molten metal head, and A thermocouple with a protective tube configured to measure the temperature in the range of 1200 ° C. or less, a load cell for measuring the weight of the melting furnace installed at the lower part of the melting furnace, the thermocouple with the protective tube, and the thermocouple; Operator connected to load cell The arithmetic means comprises a temperature change of the incineration ash layer measured by the thermocouple with a protective tube and a relational expression of a distance from a tip of the thermocouple with a protective tube to a molten metal surface of the molten slag. While calculating the distance to determine the position of the molten metal surface of the molten slag, subtract the weight of the furnace body of the melting furnace and the equipment provided in the furnace body measured by the load cell from the measured value of the load cell. The obtained weight of the molten metal in the melting furnace, the position of the molten slag obtained above, the specific gravity of the known molten slag and the molten metal, and the area of the bottom surface in the melting furnace, The feature is that the position of the metal surface is determined.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, a plurality of thermocouples with a protective tube are provided with the heights of their tips being respectively changed, and a plurality of thermocouples with a protective tube are provided. By measuring the temperature of the incineration ash layer, each of the thermocouples with the protection tube is used as a mutual backup and a warning of the upper limit of the molten slag level.

The invention according to claim 7 is the invention according to claim 5 or 6.
In the invention described above, the protection tube of the thermocouple with a protection tube is characterized by being made of a cermet heat-resistant material.

[0020]

[Function] It is obtained from the temperature change of the incineration ash layer measured by the thermocouple with the thermowell, and the relational expression between the temperature of the incineration ash layer obtained in advance and the distance from the tip of the thermocouple with the thermowell to the molten metal surface of the molten slag layer. The position of the molten metal surface (molten metal level) of the molten slag layer can be obtained from the distance. Then, the position of the molten metal surface of the molten slag determined as described above, subtracting the weight of the melting furnace body and the weight of the device provided in the furnace body measured by the load cell from the measured value of the weight of the melting furnace measured by the load cell. Based on the determined weight of the molten metal in the melting furnace, the specific gravity of the molten slag and the molten metal, and the area of the bottom surface in the melting furnace, the position of the molten metal surface can be determined by the calculating means. The thermocouple with a protective tube is inserted only into the incineration ash layer covering the upper part of the molten slag layer, since the molten metal surface of the molten slag layer S is maintained within a certain range from the molten metal surface by controlling the height of the molten metal head. The temperature of the ash layer is in the range of 1200 ° C. or lower, which is lower than the temperature of the molten slag, so that the thermocouple hardly breaks down and the life is extended. In addition, if the tip of each thermocouple with a plurality of protective tubes is arranged at different heights,
Even if the thermocouples become unavailable, they can be backed up to each other, and can also be used for checking the temperature gradient in the incineration ash layer depending on the difference in the height of the thermocouples and the respective indicated temperatures. In addition, it has the function of avoiding danger such as failure due to the approach between the thermocouple and the slag level due to the rise of the level of the molten metal, and the level gauge for the upper limit alarm of the molten slag level to prevent the slag from overflowing from the furnace body. Also used as. As a thermocouple protection tube, molybdenum and molybdenum are used as materials that are durable even if immersed in molten slag and that can withstand thermal shock when exposed to high temperatures in the ash layer directly from ambient temperature during replacement. Use a heat resistant material containing zirconia.

[0021]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing an apparatus for measuring a molten metal surface depth of an incinerated ash melting furnace according to one embodiment of the present invention, and FIG. 2 is a diagram showing a temperature change and a thermocouple of an incinerated ash layer covering a molten slag molten metal surface. It is a graph which shows the distance from a front-end | tip to a molten slag molten metal surface (molten metal surface).

In FIG. 1, 1 is an incineration ash melting furnace, 2 is a furnace main body of the incineration ash melting furnace 1, 3 is a lid placed on the upper part of the furnace main body 2, and 4 is a vertically movable through the lid 3. , Three electrodes whose tips reach the vicinity of the furnace bottom, 5 is an incineration ash inlet provided on the lid 3, 6 is a slag outlet provided on the furnace wall of the furnace body 2, 7 is a furnace wall of the furnace body 2 It is a metal discharge port provided in. 9 is a load cell for measuring the weight of the melting furnace 1 provided in the lower part of the incineration ash melting furnace 1, and 8 is a thermoelectric with a protective tube for measuring the temperature of the incineration ash layer inserted in the incineration ash layer in the furnace. The protection tube is made of a cermet refractory material containing molybdenum and zirconia. In addition, thermocouple 8 with protection tube
The thermocouples with protection tubes 10 and 11 attached at different heights are for backing up the thermocouples 8 with protection tubes and for managing the upper limit of the molten metal level. In the present embodiment, the indicated value (distance x from the tip of the thermocouple to the molten metal surface) indicated by the thermometer for liquid surface management shown in FIG.
m,) as a standard position, and from 700 ° C. (x = 150 mm)
The range of 1000 ° C. (x = 80 mm) was taken as the molten metal surface management range.

Using the apparatus for measuring the depth of the molten metal in the incineration ash melting furnace of the present embodiment, the depth of the molten metal was measured by the method of the present invention. The incineration ash introduced from the incinerator inlet 5 into the furnace body 2 is melted by the resistance heat generated by energizing the molten slag between the electrodes 4 to become a molten metal, and the molten slag and the molten metal are separated by a specific gravity difference. Is separated into On the molten slag hot surface, the input ash spreads in a layered manner due to the thermal convection of the molten slag, and a molten slag layer S, a molten metal layer M and an incinerated ash layer A are formed.

During the melting, the electrode 4 penetrates through the incineration ash layer A and is located in the molten slag S.
Of the molten slag layer S is maintained at a fixed distance from the surface of the molten slag layer S. Thus, the incinerated ash is sequentially charged from the inlet 5 while forming the molten slag layer S, the molten metal layer M, and the ash layer A in the furnace main body 2. The temperature of the incineration ash layer A at that time is measured by a thermocouple 8 with a protective tube (the thermocouples 10 and 11 are also operated as auxiliary use). At the same time, the weight of the molten metal (molten slag + molten metal) is measured. The weight of the molten metal can be obtained by subtracting the weight of the furnace body of the melting furnace and the equipment provided in the furnace body from the measured value of the weight of the melting furnace measured by the load cell 9. That is, molten metal weight = measured value of load cell− (weight of furnace main body + weight of apparatus provided in furnace main body).

The measured value of the temperature of the incinerated ash layer A by the thermocouple 8 with the protective tube and the relational expression between the temperature of the incinerated ash layer A and the distance of the molten slag S to the molten metal surface shown in FIG. The distance is calculated by calculating means to determine the position of the molten metal level (molten level) of the molten slag S. FIG. 2 is a graph showing the relationship between the temperature of the incinerated ash layer A used in the present embodiment and the distance from the tip of the protected thermocouple to the molten metal surface of the molten slag S.
For example, if the temperature measurement value of the incineration ash layer A by the thermocouple 8 with a protection tube is 900 ° C., the depth of the molten metal of the melting furnace is a distance x from the thermocouple tip to the molten metal surface of 100 mm. .

From the molten metal level (the molten metal surface of the molten slag S) measured as described above, the molten metal weight, the specific gravity of the molten metal slag and the molten metal previously determined, and the furnace floor area, the molten metal M surface ( (Molten metal level) can be obtained by calculation, and the molten slag thickness Ds and the molten metal thickness Dm can be obtained.

When the thermocouple 8 with the protection tube fails, the same management is performed by the thermocouple 10 with the protection tube. at the same time,
The thermocouple 11 with a protective tube also measures the temperature, and issues an alarm on the upper limit of the molten metal when the temperature exceeds a predetermined value. That is, when the thermocouple 11 with the protection tube issues an alarm, the molten metal level is considerably increased.

FIG. 3 is a schematic sectional view showing one embodiment of a thermocouple with a protective tube used in the present embodiment, and FIG. 4 is a sectional view of a tip portion. As shown in FIG. 3 and FIG. 4, the thermocouple 8 (10, 11) with a protection tube has a stainless steel pipe 12,
A protective tube made of cermet heat-resistant material is provided at the lower part and the tip part. 18 is a flange as a stopper, 19
Is a packing, 20 is a terminal box, 21 is a screw, and 22 is a melting furnace side flange. As shown in FIG.
Numeral 8 is located at the tip of the alumina insulating tube 13 and surrounds the alumina protective tube 14 and the surrounding alumina powder 1.
5 and the outside is covered by a cermet protection tube 16. As a material of the cermet heat resistant material, a molybdenum-zirconia (Mo-ZrO ₂ ) heat resistant material is preferable.

Each of the thermocouples with protective tubes 8, 10, 11
As means for changing the height position of the tip of each of them, short pipes 17 having different heights from the upper surface of the lid 3 are provided at three places of the lid 3,
By changing the position of the flange 18 of the thermocouple with a protective tube with the short pipe 17, the tip of each thermocouple 8, 10, 11 with the protective tube can be arranged at a desired insertion depth from the lid 3. As a result, a single type of thermocouple with a protective tube may be prepared for replacement, and it can be replaced promptly at a desired insertion depth regardless of where it is inserted.

[0031]

As described above, according to the present invention, it is possible to easily and surely determine the depth of the molten metal in the incineration ash melting furnace. And the upper limit warning of the molten metal level prevents an abnormal rise in the molten metal level (slag level) beforehand. Thermocouples with protection tubes can be replaced quickly and the depth of the molten metal level (slag layer thickness, metal layer thickness) Measurement accuracy, efficiency, and cost are greatly improved, thus providing industrially useful effects.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an apparatus for measuring a molten metal surface depth of an incineration ash melting furnace according to one embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a temperature change of an incineration ash layer covering a molten slag molten metal surface and a distance x from a thermocouple tip to a molten slag molten metal surface (molten metal surface).

FIG. 3 shows a thermocouple with a protection tube according to an embodiment of the present invention.
It is an outline sectional view showing an embodiment.

FIG. 4 shows a thermocouple with a protection tube according to an embodiment of the present invention.
It is sectional drawing of the front-end | tip part which shows embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incineration ash melting furnace 2 Furnace main body 3 Lid, 4 Electrode 5 Incineration ash inlet 6 Slag outlet 7 Metal outlet 8, 10, 11 Thermocouple with protective tube 88 Thermocouple 9 Load cell 12 Stainless steel pipe 13 Alumina insulating tube 14 Alumina protection tube 15 Alumina powder 16 Cermet protection tube 17 Short tube (1 is the length of short tube) 18 Flange 19 Packing 20 Terminal box 21 Screw 22 Melting furnace side flange

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23J 1/08 F27D 21/00 G01B 7/26

Claims (7)

(57) [Claims] An incineration ash melting furnace is provided with an outlet for molten slag on a furnace wall at an intermediate portion in a height direction, and a discharge wall for molten metal is provided on a furnace wall near the bottom of the melting furnace. The incineration ash is charged, the electrode penetrates through the incineration ash layer, inserted into the molten slag of the incineration ash, and the incineration ash is separated into the molten slag and the molten metal by electric resistance heating to separate the molten slag layer and the molten slag layer. A molten metal layer is formed, and during melting, the tip of the electrode is disposed in the molten slag layer by penetrating an incineration ash layer covering an upper portion of the molten slag layer, and the molten slag is discharged from the slag. From the mouth, in the method for measuring the molten metal surface depth of an electric resistance type incineration ash melting furnace in which the molten metal taps separately from the discharge port, the tip of a thermocouple with a protective tube is inserted into the incineration ash layer. The temperature of the incinerated ash layer is within a range of 1200 ° C. or less. And calculating the distance from the temperature change of the incineration ash layer and the relational expression of the distance from the thermocouple tip to the molten slag hot surface, thereby obtaining the position of the molten slag hot surface. Characteristic method for measuring the surface level of molten metal in incineration ash melting furnaces. 2. The position of the molten metal surface of the molten slag obtained by the method of claim 1 and the weight of the melting furnace are measured by a load cell installed in a lower part of the melting furnace, and the melting furnace is measured from the measured value of the load cell. The weight of the molten metal in the melting furnace obtained by subtracting the weight of the apparatus provided in the furnace body and the furnace body measured by the load cell, the specific gravity value of a known molten slag and a molten metal, and the melting furnace The method according to claim 1, wherein the position of the molten metal surface is calculated by the area of the bottom surface inside. 3. A thermocouple with a protective tube is provided by changing the height of the tip of each of the thermocouples, and measuring the temperature of the incinerated ash layer with each thermocouple with a protective tube. The method according to claim 1 or 2, wherein each of the thermocouples is used as a backup for each other and for an alarm on the molten slag level. 4. The method according to claim 1, wherein the protection tube of the thermocouple with the protection tube is made of a cermet heat-resistant material. 5. A furnace wall at an intermediate portion in a height direction of a melting furnace, having a slag outlet for molten slag, a furnace wall near a bottom surface of the melting furnace, having an outlet for molten metal, The electrode is inserted through the molten slag of the incinerated ash and inserted into the molten slag of the incinerated ash, and the electrical resistance heating separates the incinerated ash into a molten slag and a molten metal to form a molten slag layer and a molten metal layer therebelow. In the molten metal surface depth measuring device of the incineration ash melting furnace, the temperature of the incineration ash layer is 1200 ° C. or less by inserting only into the incineration ash layer covering the upper part of the molten slag layer by controlling the height of the molten metal head. A thermocouple with a protective tube to measure in a range, a load cell for measuring the weight of the melting furnace installed at the lower part of the melting furnace, and a calculation connected to the thermocouple with the protective tube and the load cell Means, The means calculates the distance from the temperature change of the incineration ash layer measured by the thermocouple with the protective tube and the relational expression of the distance from the tip of the thermocouple with the protective tube to the molten metal surface of the molten slag. Along with determining the position of the molten metal surface of the molten slag, the melting furnace obtained by subtracting the weight of the furnace body of the melting furnace and the weight of the device provided in the furnace body measured by the load cell from the measured value of the load cell. The weight of the molten metal, the position of the molten metal surface of the molten slag obtained above, the specific gravity value of the known molten slag and the molten metal, and the area of the bottom surface in the melting furnace, the position of the molten metal surface of the molten metal A depth measuring device for incineration ash melting furnaces, characterized in that: 6. A plurality of thermocouples with protective tubes are provided, each having a different height at the tip, and the temperature of the incinerated ash layer is measured by each thermocouple with protective tubes to provide the protection. 6. The apparatus according to claim 5, wherein each of the thermocouples with tubes is used as a backup for each other and for an alarm on the upper limit of the molten slag level. 7. The apparatus according to claim 5, wherein the protection tube of the thermocouple with a protection tube is made of a cermet heat-resistant material.