JP2008256283A - Vertical reduction melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical reduction melting furnace capable of effectively preventing damage of an inner surface furnace material constituting a connection part of a gas recovery pipe recovering high temperature gas at a temperature of 800°C or more by optimizing an upper connection part of the gas recovery pipe disposed on a side part of a furnace lower part side of a furnace body. <P>SOLUTION: The vertical reduction melting furnace is provided with the furnace body 2 and the gas recovery pipe 3, wherein the gas recovery pipe 3 is extended upward so that an angle of the upper connecting part 10 formed by an upper inner wall surface 8 and an upper inner wall surface 9 of a furnace body side part 2a is a small angle α smaller than 90° when viewed on the cross section including both of a longitudinal center axis of the furnace body 2 and an extension direction center axis of the gas recovery pipe, and chamfering with a prescribed radius of curvature R is applied to the upper connecting part 10, and a thickness of an end of the upper connection part 10 is thick enough to withstand thermal impact in the furnace. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a cylindrical furnace body for charging a processed object such as general waste or industrial waste, and melting the input processed object, and the processed object input into the furnace body. It is connected to a cylindrical gas discharge hole provided on the side of the furnace body lower than the surface position of the deposit to be deposited and higher than the tuyere provided on the furnace bottom side, and is generated when the workpiece is melted. The present invention relates to a vertical reduction melting furnace having a gas recovery pipe for recovering in-furnace gas such as combustion gas and exhaust gas as a high-temperature gas at 800 ° C. or higher.

  In recent years, so-called municipal waste, general waste, industrial waste, etc. (hereinafter simply referred to as “waste”) has increased in volume, and most of this waste has been reduced by incineration, resulting in incineration ash or incombustibility. It is landfilled at the final disposal site. However, the increase in the amount of waste discharged has developed into a problem of shortage of final disposal sites such as waste incineration residues.

An example of a means for effectively dealing with this problem is a reduction melting furnace described in Patent Document 1 proposed by the applicant.
JP 2004-132655 A

  In the reduction melting furnace described in Patent Document 1, coke and limestone are charged from the charging port as an object such as waste and auxiliary materials, and the charged object and coke are deposited and filled in the furnace. A layer is formed, and air is supplied from the upper tuyeres, the middle tuyeres and the lower tuyere, and the combustible waste and coke are reduced and burned. This combustion gas rises in the melting furnace from the lower part of the furnace and preheats, dries, and thermally decomposes the waste. In this way, the waste and auxiliary materials, coke, and limestone charged from the charging port pass through the charging damper gate valve, the moisture becomes steam, and the combustion components are pyrolyzed until reaching the packed bed, molten dripping zone and melting zone, The solid is melted. Thermal decomposition residue is taken out from the slag discharge hole. Note that high-temperature furnace gas of 800 ° C or higher, such as combustion gas and exhaust gas generated when the workpiece is melted, is sent to the post-treatment process through the inside of the gas recovery pipe and used as thermal energy, gas resources, etc. can do.

However, since the reduction melting furnace described in Patent Document 1 collects as a high-temperature gas of 800 ° C. or higher, the connection position of the gas recovery pipe to the furnace body is higher than that of the gas recovery pipe of the conventional melting furnace. It is located on the lower part of the furnace. Specifically, it is at a position that is 3 m or more lower than the high level (the surface position level of the deposit) of the packed bed in which the high-temperature-side workpiece is put in the furnace and deposited. The inner surface of the side wall at the connection position is directly exposed to a high temperature (about 800 to 2000 ° C.).

In addition, the gas recovery pipe of the melting furnace described in Patent Document 1 is connected to the side wall of the furnace lower part of the furnace body having a high furnace temperature, and the input material such as waste that has been input into the furnace is gas recovered. In order to avoid waste that has entered the pipe and cannot be treated and stays in the gas recovery pipe and prevents the clean gas from being recovered, the upper inner wall surface of the gas recovery pipe The upper connecting portion formed by the upper inner wall surface of the furnace body side portion is an acute angle portion of less than 90 ° and the furnace wall thickness is reduced. In such a case, the furnace wall thickness is reduced. A large temperature difference occurs between the inner and outer surfaces of the furnace wall of the connected part, and along with this, the inner furnace material constituting the connecting part of the gas recovery pipe may be damaged by the thermal shock and fall off. There was a problem that repairs had to be performed frequently.

An object of the present invention is to configure a gas recovery pipe connecting part for recovering high-temperature gas of 800 ° C. or higher by optimizing the upper connecting part of the gas recovery pipe provided on the side of the furnace lower part of the furnace body. Provided is a vertical reduction melting furnace that effectively prevents damage to the inner surface furnace material.

In order to achieve the above object, the gist of the present invention is as follows.
(1) A cylindrical furnace body for throwing in an object to be processed such as general waste or industrial waste, and melting the input object to be processed, and the object to be processed put in the furnace body are accumulated. Combustion that occurs when the workpiece is melted by being connected to a cylindrical gas discharge hole provided on the side of the furnace body that is lower than the surface position of the deposit and that is higher than the tuyere provided on the furnace bottom side A gas recovery pipe for recovering a furnace gas such as gas or exhaust gas as a high-temperature gas of 800 ° C. or higher, and both a longitudinal central axis of the furnace body and an extending central axis of the gas recovery pipe The gas recovery pipe has a small angle of less than 90 ° formed by the upper connecting portion formed by the upper inner wall surface and the upper inner wall surface of the furnace body side portion connected to the upper inner wall surface. Extends upward so as to form an angle, and has a predetermined radius of curvature at the upper connecting portion. Subjected to rounded chamfered tip thickness of the upper connecting portion, the vertical reduction melting furnace, characterized in that the thickness to withstand thermal shock in the furnace.

(2) The vertical reduction melting furnace according to the above (1), wherein the arrangement angle is 67 ° or less.

(3) The vertical reduction melting furnace according to (1) or (2), wherein a radius of curvature of chamfering applied to the upper connecting portion is 1/3 or more of a furnace wall thickness.

(4) The vertical reduction melting furnace according to (1), (2) or (3), wherein a cooling means is provided in the upper connecting portion.

(5) The vertical reduction melting furnace according to any one of (1) to (4), wherein a high-temperature refractory is provided at a predetermined position of the upper connection portion.

According to the present invention, the upper connecting portion formed by the upper inner wall surface of the gas recovery pipe provided on the side of the furnace lower portion of the furnace body and the upper inner wall surface of the furnace body side portion connected to the upper inner wall surface. The upper connecting portion is chamfered with a predetermined radius of curvature to extend upward so that the angle formed is a small angle of less than 90 °, and the tip thickness of the upper connecting portion is set in the furnace. By making it thick enough to withstand the thermal shock of steel, it is a highly efficient vertical reductive melting that effectively prevents damage to the internal furnace material that forms the connecting part of the gas recovery pipe that collects high-temperature gas at 800 ° C or higher. Furnace can now be provided.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an external view of a vertical reduction melting furnace according to the present invention, and FIG. 2 is an upper connection formed by an upper inner wall surface of a gas recovery pipe of the melting furnace shown in FIG. It is an enlarged view of the principal part containing a part.

A vertical reduction melting furnace 1 shown in FIG. 1 is mainly composed of a furnace body 2 and a gas recovery pipe 3.
The furnace body 2 is a part of a melting furnace for injecting coke and limestone as auxiliary materials such as general waste and industrial waste from the inlet 4 and melting the input to-be-processed object. There is a substantially cylindrical shape.

The gas recovery pipe 3 is lower than the surface position 5 of the deposit on which the object to be processed put in the furnace body 2 is deposited and more than tuyere 5a, 5b, 5c provided on the furnace bottom 4 side. It is connected to a cylindrical gas discharge hole 6 provided on the side 2a of the high furnace body 2, and the in-furnace gas 7 such as combustion gas and exhaust gas generated when the object to be processed is melted is recovered as a high-temperature gas at 800 ° C or higher. It is a part of the melting furnace. Further, as shown in FIG. 2, the gas recovery pipe 3 is an upper side of the gas recovery pipe 3 when viewed in a cross section including both the longitudinal central axis of the furnace body 2 and the central axis of the gas recovery pipe in the extending direction. An angle α formed by the upper connecting portion 10 formed by the inner wall surface 8 and the upper inner wall surface 9 of the furnace body side portion 2a connected to the upper inner wall surface 8 is less than 90 °, preferably a small angle of 67 ° or less. So as to extend upward.

The main feature of the configuration of the present invention is to optimize the upper connecting part 10 of the gas recovery pipe 3 provided on the side of the furnace body 2 on the furnace lower part 11 side, specifically, the furnace The gas recovery pipe 3 is connected to the upper inner wall surface 8 and the upper inner wall surface 8 when viewed in a cross section including both the longitudinal central axis of the body 2 and the extending central axis of the gas recovery pipe 3. The upper connecting portion 10 formed with the upper inner wall surface 9 of the furnace body side portion 2a extends upward such that the angle formed by the upper connecting portion 10 is a small angle of less than 90 °, and the upper connecting portion 10 has a predetermined curvature. By chamfering with a radius R, the tip of the upper connecting part 10 is made thick enough to withstand thermal shock in the furnace. By adopting this configuration, a high-temperature gas of 800 ° C. or higher is used. Effectively prevent damage to the inner furnace material that forms the connecting part of the gas recovery pipe be able to.

As in the conventional melting furnace having the structure shown in FIG. 1 (for example, the melting furnace shown in FIG. 1 of Patent Document 1), the gas recovery pipe is formed by the upper inner wall surface and the upper inner wall surface of the furnace body side portion. When the upper connecting portion extends upward so that the angle formed by the upper connecting portion is an acute angle, the upper connecting portion has an acute-angle shape in which the tip shape of the upper connecting portion is thin as shown by the broken line in FIG. The tip part with such an acute angle has a small heat capacity, so the heat in the furnace easily becomes higher than other parts due to the heat in the furnace, and is easily destroyed by heat. There was a problem of becoming higher.

For this reason, in the present invention, in order to prevent the distal end portion of the upper coupling portion from becoming an acute angle, the upper coupling portion 10 is chamfered with a predetermined radius of curvature R to obtain the thickness of the distal end of the upper coupling portion 10. Is made to a thickness that can withstand thermal shock in the furnace.

It is preferable that the radius of curvature R of the chamfering applied to the upper connection portion is 1/3 or more of the wall thickness t1 of the furnace body. If the radius of curvature R is less than 1/3 of the wall thickness t1 of the furnace body, the tip of the upper connecting part cannot be made sufficiently thick, so that the tip of the upper connecting part is easily damaged by thermal shock at an early stage. Because there is a tendency to become.

FIG. 3 is a diagram showing another embodiment using the temperature suppression effect. In this embodiment, a cooling pipe 13 as a cooling means is embedded in an annular shape in the upper connecting portion 10 and the lower connecting portion 12. A configuration in which a liquid such as water or non-combustible oil, or a cooling medium such as air or nitrogen is introduced into the cooling pipe 13, the medium discharged from the cooling pipe outlet is cooled by a cooler, and then circulated from the inlet again. It has further. The furnace wall portion is maintained at 1200 ° C., for example, by the cooling medium. In the illustrated example, the cooling pipe 13 is embedded in the upper connecting portion and installed, but it can be installed on the outer wall of the upper connecting portion. In this case, it is desirable to install the cooling pipe 13 on the outer wall close to the connection position of the gas recovery pipe 3 in order to increase the cooling efficiency. The cooling pipe 13 may be installed so as to surround the gas recovery pipe 3, or only the upper connecting portion 10 of the gas recovery pipe 3 may be cooled. About the extended shape of the gas recovery pipe | tube 3, it can be made to extend in arbitrary directions except a connection part.

FIG. 4 is a diagram showing another embodiment using a protective effect by a refractory. For example, the inner surface of the connecting portion 10 is covered with a sintered piece 14 made of an ultra-high heat-resistant material such as stainless steel, heat-resistant cast iron, alumina, silicon nitride, silicon carbide, zirconia, and the like to protect from the thermal power inside the furnace body. It has a configuration.
That is, FIG. 4 shows an example of a case where a sintered piece 14 made of one of the above materials is attached to the furnace material in accordance with the shape of the upper connecting portion that is easily affected by the heating power in the furnace.

  FIGS. 5A and 5B are diagrams showing another embodiment using the defense wall 15. The protective wall 15 shown in FIG. 5 (a) provided on the inner wall 9 of the furnace body 2 is, for example, a gas of the super high heat resistant material gas recovery pipe 3 such as stainless steel, heat resistant cast iron, alumina, silicon nitride, silicon carbide, zirconia. While being separated from the discharge hole 6 by a predetermined distance W, preferably 0.2 to 0.5 m, the distance L2 from the chamfered surface of the upper connecting portion to the tip position of the defense wall is set to the diameter L1 of the gas discharge hole 6. Therefore, it is arranged so as to be within an appropriate distance, preferably (1 to 2) L1, and encloses the entire gas discharge hole 6. To flow into the gas recovery pipe 3. This is because if the predetermined distance W is shorter than 0.2 m, the amount of high-temperature gas in the furnace that is recovered in the gas recovery pipe tends not to be cooked sufficiently, and the predetermined distance W is 0.5 m. This is because the effect of alleviating the temperature rise of the upper connecting portion 10 tends not to be sufficiently obtained if the length is longer than that. Further, if the distance L2 is longer than 2L1, the furnace gas tends to hardly rise into the gas recovery pipe as shown in FIG. 6, and if the distance L2 is shorter than L1, the temperature of the upper connecting portion 10 tends to increase. This is because the rise cannot be sufficiently suppressed. By providing the protective wall 15 in a predetermined positional relationship from the gas discharge hole 6 of the gas recovery pipe 3, since there is no opening at the lower part of the protective wall 15 and the surface is smooth, the hot air flow in the furnace is smooth. The temperature rise is mitigated. Since the upper connecting part 10 is not directly exposed to the hot air flow, the probability of thermal damage is further reduced.

  3 to 5 show cases where the cooling pipe 13, the sintered piece 14, and the protective wall 15 are individually provided, but in the present invention, they may be combined.

An example of a melting furnace according to the present invention is as follows. The length of the furnace body is 3 to 30 m, the diameter of the inner wall surface is 0.5 to 10 m, the wall thickness t1 of the furnace body is 0.1 to 0.5 m, and the gas recovery pipe The outer diameter is 0.3 to 3.0 m, the inner diameter is 0.1 to 2.8 m, the wall thickness t2 of the gas recovery pipe is 0.05 to 0.5 m, and the angle α formed by the upper connecting portion is 5 to 80 °.

  Next, since the waste processing was performed using the melting furnace according to the present invention, it will be described below.

Example 1
The melting furnace of Example 1 has the form shown in FIG. 1 and FIG. 2, the length of the furnace body is 10 m, the diameter of the inner wall surface is 3 m, the wall thickness t1 of the furnace body is 0.2 m, and the gas recovery pipe is The outer diameter is 1.5 m, the inner diameter is 1.1 m, the wall thickness t2 of the gas recovery pipe is 0.2 m, the angle α formed by the upper connecting portion is 40 °, and the curvature radius R of the chamfering of the upper connecting portion is 0.15 m. It is.

(Example 2)
The melting furnace of Example 2 has the form shown in FIGS. 1 and 3, and the melting furnace of Example 1 except that a cooling pipe for circulating and cooling water is embedded in the upper and lower connecting portions. Similar structure.

(Example 3)
The melting furnace of Example 3 has the form shown in FIGS. 1 and 4 and is similar to the melting furnace of Example 1 except that the chamfered outer surface of the upper connecting portion is covered with a sintered piece made of a stainless material. It has a simple structure.

Example 4
The melting furnace of Example 4 has the form shown in FIG. 1 and FIG. 5A, and has a protective wall (W = 0.3 m) made of a stainless material in order to prevent the upper connecting portion from becoming high temperature. It has the same structure as the melting furnace of Example 1 except having provided.

(Comparative example)
The melting furnace of the comparative example has the same structure as the melting furnace of Example 1 except that the upper connecting portion is not chamfered.

  Using the melting furnaces of the examples and comparative examples described above, 15 to 50 tons / day of waste was treated for one year, and the temperature measured at the outer surface position 10 of the upper connecting portion was at the start of operation (waste treatment). Was 80 ° C., but when the temperature became 300 ° C. or higher, it was assumed that the upper connecting portion needs to be repaired, and the number of times when the upper connecting portion of each melting furnace was repaired was measured. The measurement results are shown in Table 1.

  From the results shown in Table 1, it can be seen that all of the melting furnaces of Examples 1 to 4 have a smaller number of repairs of the upper connecting portion than the melting furnace of the comparative example.

  According to the present invention, as described above, there are various embodiments. In any case, the gas recovery pipe is used in a reduction melting furnace in which a gas recovery pipe is provided on the side of the furnace body, which has not been preceded by the present inventors. This solves the problem that the gas discharge holes are thermally damaged due to the high temperature of the melting furnace, thereby realizing a safer gas recovery pipe. This makes it possible to improve the heat balance more effectively in waste disposal and to eliminate the emission of harmful gases such as dioxins, and to make solid emissions harmless and effectively reuse them as resources.

1 is a schematic front view of a vertical reduction melting furnace according to the present invention. It is a figure which shows one embodiment of this invention. It is a figure which shows the other embodiment of this invention. It is a figure which shows the other embodiment of this invention. It is a figure which shows the other embodiment of this invention. It is a figure which shows the relationship between the distance L2 from the chamfering surface of an upper connection part to the front-end | tip position of a defense wall, and the diameter L1 of the gas exhaust hole 6. FIG.

Explanation of symbols

1 Vertical Reduction Melting Furnace 2 Furnace 3 Gas Recovery Pipe 4 Charger
5a, 5b, 5c Tuyere 6 Gas exhaust hole 7 Furnace gas 8 Upper inner wall surface of gas recovery pipe 9 Upper inner wall surface of furnace body side
10 Upper connection
11 Furnace lower part
12 Lower connection
13 Cooling pipe
14 Sintered pieces
15 Defense wall

Claims (5)

  Cylindrical furnace body for throwing in treated objects such as general waste and industrial waste, and melting the inputted treated objects, and deposits on which the treated objects thrown into the furnace body are deposited Combustion gas and exhaust gas generated when the object to be processed is melted, connected to a cylindrical gas discharge hole provided in the furnace body side part lower than the surface position of the furnace and higher than the tuyere provided on the furnace bottom side And a gas recovery pipe for recovering the gas in the furnace as a high-temperature gas of 800 ° C. or higher, and includes both a longitudinal central axis of the furnace body and a central axis of the gas recovery pipe in the extending direction. The gas recovery pipe has a small angle of less than 90 ° formed by the upper connecting portion formed by the upper inner wall surface and the upper inner wall surface of the furnace body side portion connected to the upper inner wall surface. So as to extend upward and round the upper connecting portion with a predetermined radius of curvature. And chamfered, the tip thickness of the upper connecting portion, the vertical reduction melting furnace, characterized in that the thickness to withstand thermal shock in the furnace. The vertical reduction melting furnace according to claim 1, wherein the arrangement angle is 67 ° or less. The vertical reduction melting furnace according to claim 1 or 2, wherein a radius of curvature of chamfering applied to the upper connecting portion is 1/3 or more of a furnace wall thickness.   The vertical reduction melting furnace according to claim 1, 2 or 3, wherein a cooling means is provided at the upper connecting portion.   The vertical reduction melting furnace according to claim 1, wherein a high-temperature refractory is provided at a predetermined position of the upper connection part.

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