JP3746533B2 - Melting furnace - Google Patents

Description

ここで、Ｔ_S 及びＴ_W は一定であるので、以下（Ｔ_S −Ｔ_W ）を除いて比較する。
【００２２】
熱ロスが同一時、即ち、開始時（符号₁ とする）における本炉の熱ロスは、下記の式（２）で表わされ、従来炉の熱ロスは、下記の式（３）で表わされる。
【数２】

ここで、両者の熱ロスが同一であるので、下記の式（４）の関係が成り立つ。
【数３】

伝熱面を比べると、本炉は冷却部分がフィンで挟まれていることにより従来炉より広くなるので、下記の式（５）の関係が成り立ち、この式（５）から下記の式（６）が導き出される。
【数４】

【００２３】
一方、一定時間経過後（符号₂ とする）における本炉の熱ロスは、下記の式（７）で表わされ、従来炉の熱ロスは、下記の式（８）で表わされる。
【数５】

ここで、両者の浸食速度について比較検討する。
従来炉は式（６）から本体のＬが短く本体の壁面内での温度勾配が急となるため、浸食に対して弱く、即ち、浸食が本炉より早く進む。よって、下記の式（９）が成り立ち、この式（９）から下記の式（１０）が成り立つ。
【数６】

【００２４】
また、浸食部分は形状があまり変化せずに浸食が進むので、下記の式（１１）が成り立つ。
【数７】

このようなことから、一定時間経過後の本炉と従来炉との熱ロスを比較すると、両者の熱ロスは式（７）及び式（８）でそれぞれ表わされるので、これら式（７）、（８）に式（１０）、（１１）を代入することにより、下記の式（１２）が得られる。
【数８】

ここで、ｘ及びｙは１よりも大きく、ｙはｘよりも大きいため、下記の式（１３）が成り立ち、この式（１３）から式（１４）が成り立つ。
【数９】

よって、式（１２）は下記の式（１５）となる。
【数１０】

従って、一定時間経過後では本炉の方が従来炉より熱ロスが少ないのである。
【００２５】
なお、前述した実施例では、プラズマアーク１２を発生させて焼却灰１１を溶融処理する溶融炉の場合について説明したが、これに限らず、被溶融体を溶融してスラグとする溶融炉であれば、前述した実施例と同様な効果を得ることができる。
【００２６】
【発明の効果】
前述したように、本発明による溶融炉では、スラグ上面の高さ位置とスラグ下面の高さ位置との間の本体の壁面部分を冷却フィンにより冷却するので、上記部分の熱負荷を軽減することができる。このため、上記部分は、浸食されにくくなり、薄くなりにくくなるので、本体の内部の熱損失量を低減することができ、溶融に要するエネルギを有効に利用することができる一方、本体の寿命を延ばすことができるので、本体の補修頻度を減少させることができ、長時間運転が可能となり、処理効率を向上させて、処理コストを低減させることができる。
【００２７】
また、冷却フィンに設けた流路に冷却水を流すことにより、スラグ上面の高さ位置とスラグ下面の高さ位置との間の本体の壁面部分の冷却効果をさらに高めることができるので、上述したような効果をさらに向上させることができる。
【００２８】
また、冷却フィンの流路にじゃま板を設けることにより、冷却フィンの内部に冷却水がまんべんなく流れるようになるので、上述した冷却効果をさらに高めることができ、上述したような効果をさらに向上させることができる。
【図面の簡単な説明】
【図１】本発明による溶融炉の一実施例の概略構造を表す断面図である。
【図２】図１の矢線II部の抽出拡大図である。
【図３】図２のIII −III 線断面矢視図である。
【図４】従来の溶融炉の一例の概略構造を表す断面図である。
【図５】図４の矢線Ｖ部の抽出拡大図である。
【符号の説明】
１ 本体
５ 冷却ジャケット
６ 下部水冷フィン
７ 上部水冷フィン
７ａ 流路
７ｂ じゃま板
７ｃ 給水口
７ｄ 排出口
１１ スラグ[0001]
[Industrial application fields]
The present invention relates to a melting furnace.
[0002]
[Prior art]
FIG. 4 shows an example of a melting furnace used for melting incineration ash generated by incineration processing of municipal waste, industrial waste, sewage sludge, and the like.
As shown in FIG. 4, an electrode 22 is inserted into the main body 21 made of a refractory material from above and below. These electrodes 22 are electrically connected to a power source 23. A base metal 24 is provided on the bottom surface inside the main body 21. A cooling jacket 25 is provided on the outer surface of the main body 21.
[0003]
In such a melting furnace, cooling water is supplied to the cooling jacket 25 to cool the periphery of the main body 21, while power is supplied from the power source 23 to the electrode 22 to generate a plasma arc 12 between the electrodes 22, The incinerated ash supplied to is melted and discharged to the outside as a slag 11 from a discharge port (not shown).
[0004]
[Problems to be solved by the invention]
In the melting furnace as described above, since the position of the discharge port is fixed, the slag 11 is always positioned at a constant height inside the main body 21. For this reason, the portion between the discharge port of the inner wall of the main body 21 and the base metal 24 not only always receives a great heat load from the slag 11 in a high temperature state, but also always receives a collision due to the flow accompanying the generation of the slag 11. Because it comes to receive, it is very easy to be eroded. When such erosion progresses, the wall surface of the main body 21 becomes thin as shown by the dotted line in FIG. 5, so that the heat loss inside the main body 21 increases and the energy required for melting increases. End up. For this reason, in the melting furnace, since the main body 21 must be repaired by frequently interrupting the melting process, not only the efficiency related to the melting process is deteriorated but also the cost related to the melting process is increased. .
[0005]
Such a problem is not limited to melting incinerated ash, but may occur sufficiently in a melting furnace that melts the material to be melted to form slag.
[0006]
[Means for Solving the Problems]
A melting furnace according to the present invention for solving the above-described problems is a melting furnace in which an object to be melted supplied to the inside of a main body into which an electrode is inserted from the upper part and the lower part is melted to form a slag. The lower water-cooling fin is attached to the main body so that the outer surface of the main body reaches a central portion inside the wall surface of the main body only at a height position lower than the upper surface position of the base metal provided on the inner bottom surface of the main body. A plurality of them are provided along the circumferential direction .
[0007]
The melting furnace according to the present invention reaches the central portion inside the wall surface of the main body at the outer surface portion of the main body which is only at a height position higher than the position of the discharge port provided above the upper surface of the base metal. Thus, a plurality of upper water cooling fins are provided along the circumferential direction of the main body .
[0008]
The melting furnace according to the present invention is characterized in that a baffle plate for causing the flow of the cooling water to meander is provided in a flow path through which the cooling water flows inside the water cooling fin .
[0009]
[Action]
According to the melting furnace of the present invention configured as described above, the wall surface portion of the main body between the height position of the slag upper surface and the height position of the slag lower surface is cooled by the cooling fins. The load is reduced.
[0010]
If a flow path as described above is provided in such a cooling fin, by flowing cooling water through the flow path, the wall surface portion of the main body between the height position of the slag upper surface and the height position of the slag lower surface is provided. Since the cooling effect can be further enhanced, the thermal load of the above part can be further reduced.
[0011]
Further, if the baffle plate as described above is provided in the flow path of the cooling fin, the cooling water flows evenly through the inside of the cooling fin, so that the cooling effect can be further enhanced.
[0012]
【Example】
One embodiment in the case of melting incineration ash using the melting furnace according to the present invention will be described with reference to FIGS. 1 is a cross-sectional view showing the schematic structure, FIG. 2 is an extracted enlarged view of a portion along arrow II in FIG. 1, and FIG. 3 is a cross-sectional view taken along line III-III in FIG.
[0013]
As shown in FIG. 1, a graphite electrode 2 is inserted into a main body 1 made of a refractory material from above and below. These electrodes 2 are electrically connected to a power source 3. A base metal 4 is provided on the bottom surface inside the main body 1. In the main body 1, a discharge port (not shown) that connects the inside and the outside is provided at a predetermined position above the upper surface of the base metal 4.
[0014]
As shown in FIGS. 1 and 2, a lower water cooling fin 6, which is a cooling fin for circulating cooling water inside, is provided on the outer surface portion of the main body 1 at a height position slightly lower than the upper surface position of the base metal 4. A plurality of lower water-cooling fins 6 are provided along the circumferential direction of the main body 1 so as to reach a central portion inside the wall surface of the main body 1. In addition, an upper water cooling fin 7 that is a cooling fin that circulates cooling water therein is provided at a central portion inside the wall surface of the main body 1 on the outer surface portion of the main body 1 that is at a slightly higher height than the position of the discharge port. A plurality of the upper water-cooling fins 7 are provided along the circumferential direction of the main body 1.
[0015]
As shown in FIG. 3, the upper water cooling fin 7 is provided with a baffle plate 7 b in which a cooling water flow path 7 a is formed and a flow of the cooling water meanders along the circumferential direction of the main body 1. The cooling water supply port 7c and the discharge port 7d are respectively formed on the outer surface. That is, when cooling water is supplied to the flow path 7a from the water supply port 7b, the cooling water flows through the baffle plate 7b while meandering through the flow path 7a and is discharged from the drain port 7d. Further, the lower water cooling fin 6 has the same structure as the upper water cooling fin 7.
[0016]
As shown in FIG. 1, a cooling jacket 5 is provided on the outer surface of the main body 1 except for the lower water cooling fins 6 and the upper water cooling fins 7.
In FIG. 1, 11 is a slag and 12 is a plasma arc.
[0017]
In such a melting furnace, cooling water is supplied to the cooling jacket 5, the lower water-cooling fin 6, and the upper water-cooling fin 7, respectively, while power is supplied from the power source 3 to the electrode 2 to generate a plasma arc 12 between the electrodes 2. The incinerated ash supplied into the main body 1 is melted and discharged as slag 11 from the discharge port to the outside.
[0018]
The slag 11 is a portion of the inner wall of the main body 1 between the outlet and the base metal 4, that is, the wall surface of the main body 1 between the height position of the upper surface of the slag 11 and the height position of the lower surface of the slag 11. Although a large heat load is applied to the part, since the lower water cooling fin 6 and the upper water cooling fin 7 sandwich the part, the part disperses the heat from the slag 11 in the direction indicated by the dotted line in FIG. However, by being absorbed by the water-cooled fins 6, 7, the heat load is greatly reduced, and erosion becomes difficult. For this reason, the said part of the wall surface of the main body 1 becomes difficult to become thin.
[0019]
Therefore, the amount of heat loss inside the main body 1 can be greatly reduced, and the energy required for melting can be used effectively, while the life of the main body 1 can be extended. It can be greatly reduced, it can be operated for a long time, the processing efficiency can be greatly improved, and the processing cost can be greatly reduced.
[0020]
The superiority of the melting furnace according to the present invention over the conventional melting furnace is considered to be as follows.
After starting the melting furnace according to the present invention (hereinafter referred to as the main furnace) and the conventional melting furnace (hereinafter referred to as the conventional furnace), it is assumed that the heat loss is the same between the main furnace and the conventional furnace. Compare the state after a certain amount of time has elapsed since the start.
Symbol T _S : Slag temperature T _{W of the} erosion portion T _W : Temperature of the cooling portion Q: Heat loss from the slag to the cooling portion A: Heat loss area from the slag to the cooling portion L: From the slag portion eroded to the main body to the cooling portion Average thickness of main body λ: Thermal conductivity of main body α: Identification code of main furnace β: Identification code of conventional furnace x, y: constant where x> 1, y> 1, x <y
[0021]
At this time, the heat loss from the slag to the cooling part can be expressed by the following formula (1).
[Expression 1]

Here, since T _S and T _W are constant, comparison is made except for the following (T _S −T _W ).
[0022]
When the heat loss is the same, that is, when starting (referred to as ₁ ), the heat loss of the main furnace is expressed by the following formula (2), and the heat loss of the conventional furnace is expressed by the following formula (3). It is.
[Expression 2]

Here, since the heat loss of both is the same, the relationship of following formula (4) is formed.
[Equation 3]

Comparing the heat transfer surfaces, this furnace is wider than the conventional furnace because the cooling part is sandwiched between the fins, so the relationship of the following formula (5) is established, and from this formula (5), the following formula (6 ) Is derived.
[Expression 4]

[0023]
On the other hand, the heat loss of the main furnace after a fixed time has elapsed (denoted by reference numeral ₂ ) is expressed by the following formula (7), and the heat loss of the conventional furnace is expressed by the following formula (8).
[Equation 5]

Here, the erosion rate of both is compared and examined.
Since the conventional furnace has a short main body L from Equation (6) and has a steep temperature gradient in the wall surface of the main body, it is weak against erosion, that is, erosion proceeds faster than the main furnace. Therefore, the following equation (9) is established, and from this equation (9), the following equation (10) is established.
[Formula 6]

[0024]
Further, since the erosion proceeds without much change in the shape of the eroded portion, the following equation (11) is established.
[Expression 7]

For this reason, when comparing the heat loss between the main furnace and the conventional furnace after a lapse of a certain time, the heat loss of both is expressed by Expression (7) and Expression (8). By substituting equations (10) and (11) into (8), the following equation (12) is obtained.
[Equation 8]

Here, since x and y are larger than 1 and y is larger than x, the following equation (13) is established, and from this equation (13), equation (14) is established.
[Equation 9]

Therefore, Expression (12) becomes the following Expression (15).
[Expression 10]

Therefore, after a certain period of time, the main furnace has less heat loss than the conventional furnace.
[0025]
In the above-described embodiment, the case of the melting furnace in which the plasma arc 12 is generated and the incinerated ash 11 is melted has been described. However, the present invention is not limited to this, and any melting furnace that melts the material to be melted to form slag. In this case, the same effect as in the above-described embodiment can be obtained.
[0026]
【The invention's effect】
As described above, in the melting furnace according to the present invention, the wall surface portion of the main body between the height position of the slag upper surface and the height position of the slag lower surface is cooled by the cooling fin, so that the thermal load of the above portion is reduced. Can do. For this reason, the portion is less likely to be eroded and less likely to be thinned, so that the amount of heat loss inside the main body can be reduced and the energy required for melting can be used effectively, while the life of the main body can be reduced. Since the main body can be extended, the frequency of repairing the main body can be reduced, the operation can be performed for a long time, the processing efficiency can be improved, and the processing cost can be reduced.
[0027]
In addition, since the cooling water is allowed to flow through the flow path provided in the cooling fin, the cooling effect of the wall surface portion of the main body between the height position of the slag upper surface and the height position of the slag lower surface can be further enhanced. Such effects can be further improved.
[0028]
In addition, by providing baffle plates in the flow path of the cooling fin, the cooling water flows evenly inside the cooling fin, so that the above-described cooling effect can be further enhanced, and the above-described effect is further improved. be able to.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a schematic structure of an embodiment of a melting furnace according to the present invention.
FIG. 2 is an enlarged view of extraction at the portion indicated by the arrow II in FIG.
3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a cross-sectional view illustrating a schematic structure of an example of a conventional melting furnace.
5 is an extracted enlarged view of a portion indicated by an arrow V in FIG. 4;
[Explanation of symbols]
1 Body 5 Cooling jacket 6 Lower water cooling fin 7 Upper water cooling fin 7a Flow path 7b Baffle plate 7c Water supply port 7d Discharge port 11 Slag

Claims (3)

An upper surface position of a base metal provided on a bottom surface of the inside of the main body, in which a melting furnace is formed by melting a melt supplied to the inside of the main body into which electrodes are respectively inserted from the upper part and the lower part. A melting furnace characterized in that a plurality of lower water-cooling fins are provided along the circumferential direction of the main body so as to reach an outer surface portion of the main body that is only at a lower height than the central portion inside the wall surface of the main body. . The upper water cooling fin is attached to the main body so as to reach the outer surface portion of the main body, which is only at a height position higher than the position of the discharge port provided above the upper surface of the base metal, up to the central portion inside the wall surface of the main body. The melting furnace according to claim 1, wherein a plurality of the melting furnaces are provided along the circumferential direction .   The melting furnace according to claim 1 or 2, wherein a baffle plate for meandering the flow of the cooling water is provided in a flow path through which the cooling water flows in the water cooling fins.

Images