JP3721569B2 - Ash melting furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ash melting furnace for melting incineration ash discharged from municipal waste incinerators and various incinerators.
[0002]
[Prior art]
Recent wastes such as municipal waste and sewage sludge are incinerated at incineration facilities such as municipal waste incinerators and various incinerators, and incineration ash and dust (hereinafter referred to as ash) generated in the incineration facilities It is melted by an ash melting facility with a furnace to reduce the volume and make it harmless. In particular, a resistance heating type melting furnace is one in which a counter electrode is placed in a molten slag, and direct current or alternating current is applied, and ash is heated and melted by electric resistance heat (Joule heat) generated using the molten slag as a resistor. It has features such as high thermal efficiency, less generated gas, no generation of arc because flicker does not occur, and separation of molten slag and molten metal.
[0003]
As an ash melting processing facility using this resistance heating type melting furnace, Japanese Patent Laid-Open No. 7-77318, “Waste Melting Processing Method and Apparatus” has been proposed. The ash melting furnace described in the published patent publication is shown in FIG. The ash melting furnace shown in this figure is a melting furnace composed of a furnace lid 1 and a furnace body 2, and includes an upper electrode 3, a lower electrode 4, an ash inlet 5, an exhaust outlet 6, a slag outlet 7, a metal outlet. It has a shed 8 and the like. The upper electrode 3 is provided through the furnace lid 2 and supported by an electrode lifting device 9 so as to be vertically movable, and an end position of the upper electrode 3 is buried in the molten slag 11 by an electrode position control device (not shown). It is controlled. The lower electrode 4 is provided at the bottom of the furnace body 2, and a power source is connected between the upper electrode 3 and the lower electrode 4, and electricity is generated between the electrodes to generate electric resistance heat using the molten slag 11 as a resistor. Thus, the molten state of the molten slag 11 is maintained. Although not shown, the upper electrode 3 may be composed of a plurality of electrodes having the same potential. The ash input port 5 is connected to an ash supply device (not shown), and the ash supply device supplies the ash discharged from the ash storage layer to the ash input port 5 via a conveyor and a hopper. The exhaust port 6 is connected to an exhaust gas treatment device (not shown). The exhaust gas treatment device renders exhaust gas generated in the furnace harmless and discharges it to the atmosphere. The slag outlet 7 and the metal outlet 8 discharge the molten slag 11 and the molten metal 12 that have reached a certain amount, respectively, continuously or intermittently. The discharged molten slag 11 and the molten metal 12 are Then, it is transported to a predetermined position by the slow cooling conveyors 13 and 13 and then used for reuse. In general, the ash 10 charged into the furnace is melted and separated into molten slag 11 and molten metal 12, and the molten slag 11 is laminated on the upper layer and the molten metal 12 is laminated on the lower layer due to the difference in specific gravity. The molten slag 11 having reached a certain amount is discharged to the outside from the slag outlet 7 by overflow or opening / closing by a slide gate valve, and the molten metal 12 having reached a certain amount is melted by a tilting device (not shown). Is tilted and discharged from the metal outlet 8 to the outside.
[0004]
[Problems to be solved by the invention]
The ash melting furnace as described above has the following problems.
(1) Since an electrode made of carbon is used as the upper electrode, the upper electrode is consumed so that it is oxidized during heating and the ash 1t is melt-treated, and the electrode is consumed by 4 to 5 kg. However, it was necessary to add electrodes.
(2) Since the upper electrode is consumed and shortened, it has been necessary to control the upper electrode to be always buried in the molten slag by the electrode lifting device and the electrode position control device.
(3) Since the upper electrode is raised and lowered, it is necessary to provide a sealing device between the melting furnace (furnace lid) so that the airtightness in the furnace is maintained and the upper electrode can be raised and lowered smoothly. there were.
(4) Since the upper electrode is directly immersed in the molten slag, it is necessary to use a carbon electrode. When the electrode is oxidized, CO gas is generated, and the exhaust gas treatment device renders the CO gas harmless. There was a need.
[0005]
On the other hand, as a result of the inventors investigating the melting furnace after the ash melting treatment, the lower electrode provided on the furnace bottom and the refractory material provided on the furnace bottom are covered with the laminated molten metal. Protected and almost exhausted. In view of this fact, the present invention has been made to solve the above-described problems. That is, by providing all electrodes that generate electrical resistance heat at the bottom of the furnace and actively protecting them with molten metal, it is possible to suppress electrode consumption and generation of CO gas, with a simple structure, An object is to provide an ash melting furnace capable of performing a safe and stable ash melting treatment.
[0006]
[Means for Solving the Problems]
According to the configuration of the present invention, the ash charged into the furnace is heated and melted by electric resistance heating, and the resulting molten slag, molten metal and exhaust gas are discharged from the slag outlet, metal outlet and exhaust outlet. In each ash melting furnace that discharges, it has insulation and fire resistance, a threshold that divides the furnace bottom into a plurality of parts, a plurality of electrodes provided in each area of the divided furnace bottom, and a connection between these electrodes And an ash melting furnace characterized in that the ash melting furnace is provided.
[0007]
According to the present invention described above, by providing a threshold for dividing the furnace bottom into a plurality of areas, a plurality of regions can be formed in the furnace bottom, and the molten metal can be divided into these regions and stacked. . By providing a pair of electrodes in the divided regions, each electrode is protected by molten metal, and a current can flow between the regions, and electric resistance heat is generated using the molten slag as a resistor. be able to. Therefore, the conventional upper electrode becomes unnecessary, and the electrode lifting device, the electrode position control device, and the sealing device become unnecessary. Furthermore, since each electrode is protected by molten metal, it is hardly consumed and CO gas is not generated. Therefore, the process of detoxifying the CO gas is not necessary. Thus, by suppressing the consumption of the electrode and the generation of CO gas, a safe and stable ash melting process can be performed with a simple structure.
[0008]
Moreover, according to the embodiment of the present invention, the metal tap is preferably provided on the furnace wall above the height of the sill.
[0009]
According to the embodiment of the present invention described above, the metal outlet is provided on the furnace wall above the height of the sill, so that even when the molten metal is stacked over the sill, the metal outlet is Without solidifying, excess molten metal can be discharged with minimal tilt.
[0010]
Furthermore, according to the embodiment of the present invention, the sill is provided so as to divide the furnace bottom into two parts, and one or a plurality of first electrodes having the same potential are provided in one region, and the other is provided. The region is preferably provided with one or a plurality of second electrodes having the same potential as that of the first electrode and having the same potential.
[0011]
According to the above-described embodiment of the present invention, the furnace bottom can be divided into two parts, and a pair of electrodes can be provided in each region, and electricity can be passed between the regions. Therefore, since the volume of each region is large, the amount of molten metal stacked in each region is large, and the operation time until the molten metal exceeds the threshold and there is no potential difference between the electrodes can be lengthened. That is, the interval of the molten metal discharge operation can be lengthened, and a more stable ash melting process can be performed.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. 1 and FIG. In addition, the same code | symbol is attached | subjected to the part which is common in the past, and the description is abbreviate | omitted.
[0013]
FIG. 1 is a side sectional view showing a configuration of an ash melting furnace of the present invention, FIG. 2 (A) shows a sectional view taken along line AA in FIG. 1, and FIG. 2 (B) shows another embodiment. It is the same figure as 2 (A). 2A and 2B, the molten slag 11 and the molten metal 12 are omitted.
As shown in these figures, the ash melting furnace of the present invention is provided in a sill 14 having insulation and fire resistance and dividing the furnace bottom into two parts, and in the divided areas 15a and 15b of the furnace bottom. The first electrode 16 and the second electrode 17, a power source connected between the electrodes 16 and 17, and a metal outlet 18 provided on the furnace wall slightly above the height of the sill 14. ing. The ash melting furnace includes a furnace lid 1 and a furnace body 2. The furnace lid 1 is provided with an ash charging port 5 and an exhaust port 6, which are connected to an ash supply device and an exhaust gas treatment device, respectively. Yes. The furnace body 2 is provided with a slag outlet 7 for discharging the molten slag 11 to the furnace wall above the metal outlet 18. Here, a DC power source is used as the power source, and the first electrode 16 is connected to the positive electrode (+) and the second electrode 17 is connected to the negative electrode (−).
[0014]
In the ash melting furnace of the present invention described above, a sill 14 is provided at the bottom of the furnace, and regions 15a and 15b surrounded by the sill 14, the furnace bottom and the furnace wall are formed, and the molten metal is divided into the regions 15a and 15b. By laminating 12, the first electrode 16 and the second electrode 17 are protected by the molten metal 12, and the electrodes 16, 17 having opposite potentials can be provided on the furnace bottom. In this way, by dividing the furnace bottom and laminating the molten metal 12, the potential difference between the electrodes 16, 17 can be maintained even if the electrodes 16, 17 having opposite potentials are provided on the furnace bottom. , 17 can be energized, electric resistance heat can be generated using the molten slag 11 as a resistor, and the ash 10 charged in the furnace can be melted. Since the molten metal 12 has not yet been formed at the time of starting, the ash 10 is charged after the conductive metal such as coke or iron scrap is charged, and the melting furnace is started.
[0015]
As shown in FIG. 1 and FIG. 2 (A), the sill 14 is a plate-shaped member having insulation and fire resistance, and is connected between the furnace walls and has a certain height from the furnace bottom. It constitutes. Therefore, when the molten metal 12 is laminated so as to exceed the threshold 14, there is no potential difference between the electrodes 16 and 17, and the ash 10 cannot be heated. By measuring the potential difference between the electrodes 16 and 17, the lamination level of the molten metal 12 can be detected. When the potential difference between the electrodes 16 and 17 disappears, the melting furnace is tilted by a tilting device (not shown), Excess molten metal 12 is discharged from the metal outlet 18. At this time, since it is necessary to protect the electrodes 16 and 17 by covering them with the molten metal 12, it is not necessary to discharge all the laminated molten metal 12. In fact, in the lower part of the laminated molten metal 12, Since it has already solidified, the solidified part remains even if the melting furnace is tilted, and only the molten part of the upper part is discharged. Moreover, if the metal tap 18 is provided at a position lower than the height of the threshold 14, the metal tap 18 may be buried in the laminated molten metal 12 and solidify. Therefore, it is necessary to provide it at a position higher than the sill 14, and in order to minimize the tilt when discharging the molten metal 12, it is better to be as close to the height of the sill 14 as possible. 18 is provided at a position slightly higher than the threshold 14. In order to discharge the excess molten metal 12 in each of the regions 15a and 15b evenly from the metal outlet 18, it may be provided on the same straight line as the sill 14, as shown in FIG. In addition, a metal tap 18 may be provided for each of the regions 15a and 15b so that they are alternately tilted.
[0016]
As shown in FIG. 2A, each of the regions 15a and 15b may be provided with a single first electrode 16 and a second electrode 17, and a positive electrode (+) is provided in the region 15a. In the region 15b, a plurality of negative electrode (-) electrodes may be provided in pairs. Further, as shown in FIG. 2B, the sill 14 may be formed of a circular member, and the regions 15 a and 15 b may be divided into the inside and the outside of the sill 14. In this case, for example, a single second electrode 17 serving as a negative electrode (−) is provided in the inner region 15b, and a plurality of (four in the figure) first electrodes 16 serving as positive electrodes (+) are provided in the outer region 15a. You may make it provide. As shown in FIGS. 2 (A) and 2 (B), when the furnace bottom is divided into two, the volume of each region 15a, 15b is large. Therefore, the amount of molten metal 12 laminated in each region 15a, 15b is large, and the molten metal It is possible to lengthen the operation time until the potential difference between the electrodes 16 and 17 disappears after 12 exceeds the threshold 14, and the interval between discharge operations of the molten metal 12 can be lengthened to perform more stable operation. it can. Further, although not shown, a plurality of thresholds 14 may be provided to divide the furnace bottom into three or more regions. When three or more regions are configured on the furnace bottom, a pair of electrodes to be energized can be arbitrarily selected, so that the vicinity of the slag outlet 7 is mainly heated or the molten slag 11 The temperature distribution can be changed. Therefore, the molten slag 11 can be discharged smoothly, or the molten slag 11 can be uniformly stirred to produce a homogeneous molten slag 11.
[0017]
According to the ash melting furnace of the present invention described above, since the electrodes 16 and 17 that generate electrical resistance heat are not directly immersed in the molten slag 11, there is no need to use a carbon electrode, and a conductive ceramic or the like is used instead. Furthermore, it is always protected by the molten metal 12 during operation. Therefore, the electrodes 16 and 17 are hardly consumed and no CO gas is generated. Since all the electrodes 16 and 17 are provided on the furnace bottom and consumption of the electrodes 16 and 17 is suppressed, it is not necessary to provide an electrode lifting / lowering device, a sealing device, an electrode position control device, and the like. Therefore, the ash melting furnace can be simplified and reduced in weight, the melting furnace can be easily tilted and installed, and stable operation can be performed. Further, since no electrode is provided on the furnace lid 1, the ash charging port 5 and the exhaust port 6 can be freely provided. For example, the ash charging port 5 is provided at the center of the furnace lid 1 as shown in FIG. Thus, the ash 10 can be charged almost uniformly into the furnace, or the exhaust port 6 can be enlarged to exhaust the exhaust gas efficiently. Moreover, since the lamination | stacking level of the molten metal 12 can be detected only by measuring the electrical potential difference between the electrodes 16 and 17, the level can be detected easily and it is not necessary to provide a special level measuring device. Furthermore, by suppressing the generation of CO gas, it is not necessary to provide a CO gas treatment process for detoxifying harmful CO gas in the exhaust gas treatment device, and safe operation can be performed.
[0018]
It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention, such as using an AC power supply as a power supply.
[0019]
【The invention's effect】
According to the ash melting furnace of the present invention described above, the region divided into the furnace bottom is configured, electrodes are provided in each region, molten metal is laminated in each region, and electricity is passed between the regions. All the electrodes that generate electric resistance heat can be provided at the bottom of the furnace, and these electrodes can be protected by molten metal. Therefore, consumption of electrodes and generation of CO gas can be suppressed, and a safe and stable ash melting process can be performed with a simple structure. In addition, by providing a metal outlet on the furnace wall slightly above the height of the sill, even if molten metal is stacked over the sill, the metal outlet does not solidify, and surplus The molten metal can be discharged with a minimum tilt, and an excellent effect such as a more stable ash melting process can be achieved.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a configuration of an ash melting furnace of the present invention.
2A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 2B is a view similar to FIG. 2A showing another embodiment.
FIG. 3 is a diagram showing an ash melting furnace described in Japanese Patent Laid-Open No. 7-77318 “Waste Melting Method and Apparatus”.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Furnace 2 Furnace body 3 Upper electrode 4 Lower electrode 5 Ash inlet 6 Exhaust port 7 Slag outlet 8 Metal outlet 9 Electrode raising / lowering device 10 Ash 11 Molten slag 12 Molten metal 13 Slow cooling conveyor 14 Sill 15 Area 16 First electrode 17 Second electrode 18 Metal outlet

Claims (3)

In an ash melting furnace that heats and melts the ash charged in the furnace by electric resistance heating, and discharges the generated molten slag, molten metal, and exhaust gas from the slag outlet, metal outlet, and exhaust, respectively.
It has a sill that has insulation and fire resistance and divides the furnace bottom into a plurality of parts, a plurality of electrodes provided in each region of the divided furnace bottom, and a power source connected between the electrodes, An ash melting furnace characterized by that. The ash melting furnace according to claim 1, wherein the metal tap is provided on a furnace wall above the height of the sill. The sill is provided so as to divide the furnace bottom in two, and one or more first electrodes having the same potential are provided in one area, and the other electrode has a potential opposite to that of the first electrode. The ash melting furnace according to claim 1, wherein one or a plurality of second electrodes having the same potential are provided.

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